US20020014630A1 - Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element - Google Patents

Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element Download PDF

Info

Publication number
US20020014630A1
US20020014630A1 US09/893,925 US89392501A US2002014630A1 US 20020014630 A1 US20020014630 A1 US 20020014630A1 US 89392501 A US89392501 A US 89392501A US 2002014630 A1 US2002014630 A1 US 2002014630A1
Authority
US
United States
Prior art keywords
layer
light emitting
emitting element
light
electrode
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US09/893,925
Inventor
Haruhiko Okazaki
Hideto Sugawara
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toshiba Corp
Original Assignee
Toshiba Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toshiba Corp filed Critical Toshiba Corp
Assigned to KABUSHIKI KAISHA TOSHIBA reassignment KABUSHIKI KAISHA TOSHIBA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: OKAZAKI, HARUHIKO, SUGAWARA, HIDETO
Publication of US20020014630A1 publication Critical patent/US20020014630A1/en
Priority to US10/417,873 priority Critical patent/US6825502B2/en
Priority to US10/945,707 priority patent/US7179671B2/en
Priority to US10/947,631 priority patent/US7135714B2/en
Priority to US10/946,787 priority patent/US7138665B2/en
Priority to US10/946,668 priority patent/US7138664B2/en
Priority to US10/958,910 priority patent/US20050056857A1/en
Priority to US10/958,911 priority patent/US7221002B2/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/40Materials therefor
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/40Materials therefor
    • H01L33/405Reflective materials
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02Bonding areas; Manufacturing methods related thereto
    • H01L2224/04Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/05001Internal layers
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02Bonding areas; Manufacturing methods related thereto
    • H01L2224/04Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/05001Internal layers
    • H01L2224/0502Disposition
    • H01L2224/05023Disposition the whole internal layer protruding from the surface
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02Bonding areas; Manufacturing methods related thereto
    • H01L2224/04Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/05001Internal layers
    • H01L2224/05075Plural internal layers
    • H01L2224/0508Plural internal layers being stacked
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02Bonding areas; Manufacturing methods related thereto
    • H01L2224/04Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/0554External layer
    • H01L2224/0556Disposition
    • H01L2224/05568Disposition the whole external layer protruding from the surface
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02Bonding areas; Manufacturing methods related thereto
    • H01L2224/04Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H01L2224/0554External layer
    • H01L2224/05573Single external layer
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02Bonding areas; Manufacturing methods related thereto
    • H01L2224/04Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/06Structure, shape, material or disposition of the bonding areas prior to the connecting process of a plurality of bonding areas
    • H01L2224/061Disposition
    • H01L2224/06102Disposition the bonding areas being at different heights
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10Bump connectors; Manufacturing methods related thereto
    • H01L2224/15Structure, shape, material or disposition of the bump connectors after the connecting process
    • H01L2224/16Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
    • H01L2224/161Disposition
    • H01L2224/16135Disposition the bump connector connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip
    • H01L2224/16145Disposition the bump connector connecting between different semiconductor or solid-state bodies, i.e. chip-to-chip the bodies being stacked
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/10Bump connectors; Manufacturing methods related thereto
    • H01L2224/15Structure, shape, material or disposition of the bump connectors after the connecting process
    • H01L2224/17Structure, shape, material or disposition of the bump connectors after the connecting process of a plurality of bump connectors
    • H01L2224/1701Structure
    • H01L2224/1703Bump connectors having different sizes, e.g. different diameters, heights or widths
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321Disposition
    • H01L2224/32151Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32245Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805Shape
    • H01L2224/4809Loop shape
    • H01L2224/48091Arched
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481Disposition
    • H01L2224/48151Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48247Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481Disposition
    • H01L2224/48151Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48257Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a die pad of the item
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42Wire connectors; Manufacturing methods related thereto
    • H01L2224/47Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/491Disposition
    • H01L2224/49105Connecting at different heights
    • H01L2224/49107Connecting at different heights on the semiconductor or solid-state body
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732Location after the connecting process
    • H01L2224/73251Location after the connecting process on different surfaces
    • H01L2224/73265Layer and wire connectors
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/73Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/00014Technical content checked by a classifier the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01Chemical elements
    • H01L2924/01019Potassium [K]
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10Details of semiconductor or other solid state devices to be connected
    • H01L2924/11Device type
    • H01L2924/12Passive devices, e.g. 2 terminal devices
    • H01L2924/1204Optical Diode
    • H01L2924/12041LED
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/30Technical effects
    • H01L2924/301Electrical effects
    • H01L2924/3025Electromagnetic shielding
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/26Materials of the light emitting region
    • H01L33/30Materials of the light emitting region containing only elements of group III and group V of the periodic system
    • H01L33/32Materials of the light emitting region containing only elements of group III and group V of the periodic system containing nitrogen

Definitions

  • the present invention relates to a light emitting element and, more particularly, to the electrode structure of a light emitting element.
  • LEDs light emitting diodes
  • Red, orange, yellow, and green LEDs currently put to practical use are made of group III-V compound semiconductors using As and P as group V elements, e.g., AlGaAs, GaAlP, GaP, and InGaAlP.
  • group III-V compound semiconductors using As and P as group V elements, e.g., AlGaAs, GaAlP, GaP, and InGaAlP.
  • green, blue, and ultraviolet LEDs are made of compound semiconductors such as GaN. In this way, LEDS having high emission intensity are realized.
  • FIG. 1 shows the structure of a conventional violet LED.
  • a light emitting element 110 for emitting violet light is bonded on a lead frame 120 by silver paste 130 .
  • the p- and n-electrodes of this light emitting element 110 are connected to the lead frame 120 by bonding wires 150 .
  • the light emitting element 110 is covered with an epoxy resin 180 .
  • FIG. 2 shows the light emitting element shown in FIG. 1.
  • n-GaN layer 210 and a p-GaN layer 220 are formed on a sapphire (Al 2 O 3 ) substrate 200 .
  • the n-GaN layer 210 has a recess. Since the p-GaN layer 220 is not present on this recess, the n-GaN layer 210 is exposed in this recess of the n-GaN layer 210 .
  • An n-side electrode 230 is formed on the recess of the n-GaN layer 210 .
  • a transparent electrode 240 having properties of transmitting light is formed on the p-GaN layer 220 .
  • a bonding electrode 250 for wire bonding is formed on the p-GaN layer 220 .
  • the light transmittance and the conductivity have a relationship of trade-off.
  • the thickness of the electrode need only be decreased. However, if the electrode thickness is decreased, the conductivity lowers. When the conductivity lowers, no electric current can be supplied to the whole p-n junction any longer, and this decreases the light generation efficiency. Also, to increase the conductivity, the thickness of the electrode need only be increased. However, if the electrode thickness is increased, the light transmittance lowers. When the light transmittance lowers, light generated in the p-n junction cannot be efficiently extracted to the outside of the chip.
  • FIG. 3 shows a light emitting element using this technology.
  • this light emitting element is bonded on a lead frame by flip chip bonding, an LED having this light emitting element is called a flip chip type LED.
  • a high-reflectance electrode 260 is formed on p-GaN 220 .
  • light traveling to a sapphire substrate 200 is directly emitted to the outside of the chip.
  • light heading to the electrode 260 is reflected by this electrode 260 .
  • the reflected light travels to the sapphire substrate 200 and is emitted to the outside of the chip.
  • the sapphire substrate 200 will be described below.
  • the bandgap of the sapphire substrate 200 is approximately 3.39 eV (wavelength ⁇ 365 nm) at room temperature (300 K). That is, the sapphire substrate 200 has properties of transmitting light within the range of blue to green (the wavelength ⁇ is approximately 400 to 550 nm).
  • a flip chip type LED is very effective as a technology of extracting light to the outside of the chip with high efficiency, but also has a problem.
  • the electrode 260 is given a two-layered structure including an ohmic layer for forming an ohmic contact and a high-reflection layer having high reflectance.
  • the ohmic layer improves the performance and the high-reflection layer increases the light emission efficiency at the same time.
  • the ohmic layer obtains an ohmic contact by interdiffusion of metal atoms between this ohmic layer and the p-GaN 220 , so these metal atoms naturally diffuse from the ohmic layer to the high-reflection layer. Since this diffusion lowers the performance and reliability of the light emitting element, it must be eliminated.
  • FIG. 4 shows an LED made of group III-V compound semiconductors having As and P as group V elements.
  • This LED emits light within the range of red to green.
  • an n-GaAs buffer layer 310 and an n-InGaAlP cladding layer 320 are formed on an n-GaAs substrate 300 .
  • an InGaAlP active layer 330 , a p-InGaAlP cladding layer 340 , and a p-AlGaAs current diffusing layer 350 are formed on an n-GaAs substrate 300 .
  • a p-GaAs contact layer 360 and a p-side electrode 370 are formed on the p-AlGaAs current diffusing layer 350 .
  • An n-side electrode 380 is formed on the back side of the n-GaAs substrate 300 .
  • a sufficiently thick current diffusing layer (the AlGaAs current diffusing layer 350 ) is formed on a p-semiconductor layer without forming any transparent electrode on a p-semiconductor layer (the InGaAlP cladding layer 340 ).
  • This sufficiently thick current diffusing layer has a function of evenly injecting an electric current into the entire InGaAlP active layer 330 . Since the AlGaAs current diffusing layer 350 increases the light generation efficiency in the vicinity of the active layer, satisfactory optical power can be assured.
  • an electric current given to the p-side electrode 370 is injected into the InGaAlP active layer 330 via the p-AlGaAs current diffusing layer 350 .
  • Light generated near the InGaAlP active layer 330 is emitted upward from the p-AlGaAs current diffusing layer 350 except for a region where the p-side electrode 370 exists.
  • the film thickness, however, of the current diffusing layer 350 must be increased to well diffuse the electric current for the reason explained below. That is, if the film thickness is small, the electric current is not diffused but injected only into the active layer 330 immediately below the p-side electrode 370 . Consequently, most of the light generated near the active layer 330 is interrupted by the p-side electrode 370 .
  • MO-CVD Metal Organic-Chemical Vapor Deposition
  • MBE Molecular Beam Epitaxy
  • the light generated in the InGaAlP active layer 330 is absorbed by the n-GaAs substrate 300 . This lowers the light extraction efficiency of the light emitting element shown in FIG. 4.
  • the GaAs substrate 300 As a method of solving this problem of light absorption by the GaAs substrate 300 , it is possible to form a flip chip type LED described earlier. However, the GaAs substrate 300 is opaque. Accordingly, a device from which this GaAs substrate 300 is removed is prepared, and a transparent substrate which transmits light is bonded to this device.
  • FIG. 5 shows a light emitting element using this technology.
  • a p-InGaAlP adhesive layer 410 and a p-InGaAlP cladding layer 420 are formed on a p-GaP substrate 400 .
  • An InGaAlP active layer 430 is formed on the p-InGaAlP cladding layer 420 .
  • an n-InGaAlP cladding layer 440 and an n-AlGaAs window layer 450 are formed.
  • an electrode 460 having high reflectance and an n-side electrode 470 are formed on the AlGaAs window layer 450 .
  • a p-side electrode 480 is formed on the back side of the p-GaP substrate 400 .
  • the GaP substrate 400 has a bandgap of 2.26 eV ( ⁇ 548 nm) at room temperature and is transparent to red light.
  • this electrode 460 is given a two-layered structure including an ohmic layer and high-reflection layer. In this case, as described previously, the interdiffusion of metals between the ohmic layer and the high-reflection layer is a problem.
  • FIG. 6 shows a light emitting element using the technology of bonding a GaP substrate to a device from which a GaAs substrate is removed.
  • this light emitting element shown in FIG. 6 is characterized by having no high-reflectance electrode on the n-AlGaAs window layer 450 .
  • an alloy layer produced in the boundary between the p-GaP substrate 400 and the p-side electrode 480 scatters and absorbs light. This makes effective extraction of light to the outside of the chip difficult.
  • n-side electrode is formed on a portion of a light emitting layer and a thick current diffusing layer is formed below this n-side electrode
  • the n-side electrode on the light emitting layer must have high reflectance.
  • This high-reflectance n-side electrode can be realized by using a two-layered structure including an ohmic layer and high-reflection layer as an electrode structure. In this case, however, the interdiffusion of metals between the ohmic layer and the high-reflection layer is a problem.
  • a light emitting element of the present invention comprises a substrate, a light emitting element formed on the substrate to emit light, and a first electrode contacting the light emitting layer.
  • This first electrode includes an ohmic layer in ohmic contact with the light emitting layer, a first barrier layer formed on the ohmic layer to prevent diffusion of metal atoms, and a light reflecting layer formed on the first barrier layer to reflect light.
  • FIG. 1 is a view showing a conventional LED
  • FIG. 2 is a view showing the first example of a conventional light emitting element
  • FIG. 3 is a view showing the second example of a conventional light emitting element
  • FIG. 4 is a view showing the third example of a conventional light emitting element
  • FIG. 5 is a view showing the fourth example of a conventional light emitting element
  • FIG. 6 is a view showing the fifth example of a conventional light emitting element
  • FIG. 7 is a view showing an LED of the present invention.
  • FIG. 8 is a view showing the first embodiment of a light emitting element of the present invention.
  • FIG. 9 is a view showing one step of a manufacturing method of the present invention.
  • FIG. 10 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 11 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 12 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 13 is a graph showing the relationship between the electric current and optical output of the light emitting element shown in FIG. 8;
  • FIG. 14 is a graph showing the relationship between the thickness and reflectance of a reflecting layer of the light emitting element shown in FIG. 8;
  • FIG. 15 is a graph showing the relationship between the thickness of reflectance of an ohmic layer of the light emitting element shown in FIG. 8;
  • FIG. 16 is a view showing a modification of the light emitting element shown in FIG. 8;
  • FIG. 17 is a view showing the second embodiment of the light emitting element of the present invention.
  • FIG. 18 is a view showing a modification of the light emitting element shown in FIG. 17;
  • FIG. 19 is a view showing the third embodiment of the light emitting element of the present invention.
  • FIG. 20 is a view showing a modification of the light emitting element shown in FIG. 19;
  • FIG. 21 is a view showing the fourth embodiment of the light emitting element of the present invention.
  • FIG. 22 is a view showing one step of a manufacturing method of the present invention.
  • FIG. 23 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 24 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 25 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 26 is a view showing a modification of the light emitting element shown in FIG. 21;
  • FIG. 27 is a graph showing the relationship between the electric current and optical output of the light emitting element shown in FIG. 21;
  • FIG. 28 is a view showing the fifth embodiment of the light emitting element of the present invention.
  • FIG. 29 is a view showing one step of a manufacturing method of the present invention.
  • FIG. 30 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 31 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 32 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 33 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 34 is a view showing one step of the manufacturing method of the present invention.
  • FIG. 7 shows a lamp type LED of the present invention.
  • a submount 13 is placed on a lead frame 12 .
  • This submount 13 is made of, e.g., a silicon substrate.
  • high-conductivity ohmic electrodes 14 - 1 and 14 - 2 having a thickness of about 100 ⁇ m are formed.
  • the positions of these ohmic electrodes 14 - 1 and 14 - 2 match the positions of electrodes of a light emitting element 11 .
  • the ohmic electrodes 14 - 1 and 14 - 2 are physically separated from each other, and an insulating film 19 is formed only immediately below the ohmic electrode 14 - 2 .
  • This ohmic electrode 14 - 2 is electrically connected to the lead frame 12 by a bonding wire 15 .
  • the lower surface of the submount 13 is adhered to the lead frame 12 by a conductive paste 16 .
  • the light emitting element 11 for emitting violet light is placed on the submount 13 .
  • This light emitting element 11 has p- and n-side electrodes.
  • the light emitting element 11 is bonded on the submount 13 by flip chip bonding by using AuSn 17 .
  • the light emitting element 11 is covered with an epoxy resin 18 .
  • FIG. 8 shows the light emitting element shown in FIG. 7.
  • An n-GaN layer 21 is formed on a sapphire substrate 20 .
  • an InGaN active layer 22 On this n-GaN layer 21 , an InGaN active layer 22 , a p-AlGaN cladding layer 23 , and a p-GaN layer 24 are formed.
  • the n-GaN layer 21 has a recess at the edge of the sapphire substrate 20 . Since the InGaN active layer 22 , the p-AlGaN cladding layer 23 , and the p-GaN layer 24 do not exist on this recess, the n-GaN layer 21 is exposed in this recess.
  • An n-side electrode 25 is formed on the n-GaN layer 21 in the recess.
  • a p-side electrode 26 is formed on the p-GaN layer 24 .
  • the surfaces of the n-GaN layer 21 , the InGaN active layer 22 , the p-AlGaN cladding layer 23 , and the p-GaN layer 24 are covered with an insulating film 27 , except for regions where the n-side electrode 25 and the p-side electrode 26 are formed.
  • the n-side electrode 25 has a four-layered structure.
  • This four-layered structure includes a Ti layer 28 , an Al layer 29 , a Ti layer 30 , and an Au layer 31 in this order from the n-GaN layer 21 .
  • the p-side electrode 26 has a five-layered structure.
  • This five-layered structure includes an Ni layer 32 , an Mo layer 33 , an Al layer 34 , a Ti layer 35 , and an Au layer 36 in this order from the p-GaN layer 24 .
  • the Ni layer 32 is an ohmic layer for achieving an ohmic contact with the p-GaN layer 24 .
  • the thickness of this Ni layer 32 is set to about 4 nm.
  • the Mo layer 33 and the Ti layer 35 function as barrier layers for preventing diffusion of impurities.
  • the Al layer 34 reflects light at high reflectance.
  • the Au layer 36 functions as an overcoat electrode for improving the contact with the submount 13 .
  • the light emitting element shown in FIG. 8 is bonded by flip chip bonding on the submount 13 with the back side of the sapphire substrate 20 facing up.
  • the light generated in the InGaN layer 22 makes a round trip along the path passing through the Ni layer 32 and the Mo layer 33 .
  • the Ni layer 32 and the Mo layer 33 are sufficiently thinned to have a low light scattering coefficient and a low light absorption coefficient.
  • MO-CVD is used to form an undoped GaN buffer layer on a sapphire substrate 20 and form an n-GaN layer 21 on this buffer layer.
  • an InGaN active layer 22 is formed on the n-GaN layer 21 by MO-CVD or MBE.
  • This InGaN active layer 22 can have an SQW (Single Quantum Well) structure or an MQW (Multiple Quantum Well) structure.
  • a p-AlGaN cladding layer 23 and a p-GaN layer 24 are formed on the InGaN active layer 22 by MO-CVD.
  • lithography and anisotropic etching such as RIE (Reactive Ion Etching) are used to remove portions of the p-GaN layer 24 , the p-AlGaN cladding layer 23 , the InGaN active layer 22 , and the n-GaN layer 21 , thereby forming a recess in the edge of the sapphire substrate 20 .
  • an insulating film 27 is formed on the surfaces of the p-GaN layer 24 , the p-AlGaN cladding layer 23 , the InGaN active layer 22 , and the n-GaN layer 21 by CVD.
  • This recess can also be formed by isotropic etching such as wet etching, rather than by anisotropic etching such as RIE.
  • lithography and wet etching are used to remove a portion of the insulating film 27 on the n-GaN layer 21 .
  • a Ti layer 28 and an Al layer 29 are formed by vacuum evaporation and lift-off.
  • the structure is annealed in a nitrogen atmosphere at about 600° C. to form an ohmic contact between the n-GaN layer 21 and the Ti layer 28 .
  • lithography and wet etching are used to remove a portion of the insulating film 27 on the p-GaN layer 24 .
  • an Ni layer 32 about 4 nm thick, an Mo layer 33 about 1 nm thick, and an Al layer 34 about 500 nm thick are formed by vacuum evaporation and lift-off.
  • vacuum evaporation and lift-off are used to form Ti layers 30 and 35 about 100 nm thick and Au layers 31 and 36 about 1,000 nm thick on the Al layers 29 and 34 , respectively.
  • flash annealing is performed at a temperature of about 200° C. or more (favorably about 250° C.) for 20 sec.
  • the temperature of this flash annealing is set to be lower than that of flash annealing performed in the step shown in FIG. 12, if flash annealing is performed in the step shown in FIG. 12.
  • a semiconductor element of the present invention is completed by the above method.
  • the semiconductor element manufactured by the above method is packaged to form an LED (semiconductor device) of the present invention.
  • the light emitting element 11 is mounted on the submount 13 having the ohmic electrodes 14 - 1 and 14 - 2 made of an Au layer about 3 ⁇ m thick by flip chip bonding. Consequently, the n-side electrode 25 is connected to the electrode 14 - 1 by the bump (e.g., AuSn, PbSn, AgSn) 17 , and the p-side electrode 26 is connected to the electrode 14 - 2 by the bump 17 .
  • the bump e.g., AuSn, PbSn, AgSn
  • the submount 13 on which the light emitting element 11 is mounted is adhered to the cup type lead frame 12 by using the conductive paste 16 .
  • the electrode 14 - 1 is electrically connected to the cup type lead frame 12 .
  • the electrode 14 - 2 and the lead frame 12 are electrically connected by wire bonding.
  • the light emitting element 11 is covered with the epoxy resin 18 .
  • the n-side electrode can also be formed on the back side of this n-GaN substrate.
  • the p-side electrode 26 has the Ni layer 32 for forming an ohmic contact with the p-GaN layer 24 , the Mo layer 33 having a barrier function of blocking impurity diffusion, and the Al layer 34 having high reflectance to light generated in the element.
  • the p-side electrode is conventionally composed of an ohmic layer for forming an ohmic contact and a high-reflection layer for reflecting light generated in the element.
  • the barrier layer (e.g., Mo layer) 33 made of a high-melting metal is formed between the Ni layer 32 as an ohmic layer and the Al layer 34 as a high-reflection layer.
  • This barrier layer prevents interdiffusion of metal atoms between the ohmic layer and the high-reflection layer. Accordingly, the present invention can prevent a rise of the operating voltage of the LED.
  • the ohmic layer (Ni layer 32 ) and the barrier layer (Mo layer 33 ) are made of materials substantially opaque to light generated in the element. By decreasing the thicknesses of these layers, the light reflectance of the high-reflection layer (Al layer 34 ) can be increased.
  • FIG. 13 shows the emission characteristic of the GaN violet type LED of the present invention.
  • This emission characteristic is represented by the relationship between the electric current injected into the LED and its optical output (emission intensity).
  • the solid line indicates the emission characteristic of the GaN violet type LED according to the present invention, and the broken line indicates that of a conventional LED.
  • the optical output of the LED according to the present invention is about 1.7 times that of the conventional LED.
  • the optical output of the conventional LED is about 4.0 mW
  • the optical output reduced to about 80% of the initial value. This is a very good result compared to the conventional LED and indicates that the reliability of the LED of the present invention improved.
  • FIG. 14 shows the relationship between the thickness of the Mo layer as a barrier layer and the light reflectance of the Al layer as a high-reflection layer.
  • the thickness of the Ni layer as an ohmic layer is fixed to 4 nm
  • the thickness of the Al layer as a high-reflection layer is fixed to 100 nm.
  • FIG. 15 shows the relationship between the thickness of the Ni layer as an ohmic layer and the Al layer as a high-reflection layer.
  • the thickness of the Mo layer as a barrier electrode is fixed to 1 nm
  • the thickness of the Al layer as a high-reflection layer is fixed to 100 nm.
  • the light reflectance of the Al layer largely depends upon the thicknesses of the barrier layer and the ohmic layer; the smaller the thicknesses of these layers, the higher the light transmittance.
  • the thickness of the ohmic layer into which light generated in the InGaN active layer initially enters is preferably as small as possible.
  • this ohmic layer is made of Ni, its thickness is set to 10 nm or less.
  • the ohmic layer can be formed using materials such as Pt, Mg, Zn, Be, Ag, Au, and Ge and compounds consisting primarily of these materials, in addition to Ni.
  • the barrier layer can be formed using materials such as W, Pt, Ni, Ti, Pd and V and compounds consisting primarily of these materials, in addition to Mo.
  • ohmic layer and barrier layer can be integrated into a single layer if they are formed using the same material (Ni or Pt).
  • the Ti layer 35 as a barrier layer and the Au layer 36 as an overcoat layer are formed on the Al layer 34 as a high-reflection layer.
  • a conductor pattern of Au is written on a submount on which a light emitting element is to be mounted. A light emitting element is adhered onto this conductor pattern.
  • a high-reflection layer made of Al or Ag is brought into direct contact with the Au conductor pattern, a high-resistance layer may be formed on the bonding surface between them, or the bonding power between them weakens.
  • an overcoat layer made of the same material as the conductor pattern (e.g., Au) on the submount is formed, thereby preventing the generation of a high-resistance layer and increasing the bonding power between the light emitting element and the submount.
  • the barrier layer (Ti layer 35 ) made of a high-melting metal is formed between the overcoat layer and the high-reflection layer. Since this barrier layer prevents diffusion of metal atoms from the overcoat layer to the high-reflection layer, the bonding power between the overcoat layer and the conductor pattern can be increased.
  • This barrier layer interposed between the overcoat layer and the high-reflection layer can be formed using materials such as W, Mo, Pt, Ni, Ti, Pd, and V and compounds consisting primarily of these materials, in addition to Ti.
  • the light emitting element is not in direct contact with the lead frame but is mounted on the lead frame via the submount.
  • heat generated in the light emitting element is efficiently radiated via the submount. This can increase the heat radiation efficiency and improve the reliability of the LED.
  • FIG. 16 shows a modification of the light emitting element shown in FIG. 8.
  • an n-InGaAlP adhesive layer 41 and an n-InGaAlP cladding layer 42 are formed on an n-GaP substrate 40 .
  • an InGaAlP active layer 43 is formed on this n-InGaAlP cladding layer 42 .
  • InGaAlP a direct transition type band structure is used to obtain red light to green light, unlike AlGaAs for which an indirect transition type band structure is used to obtain green light.
  • a p-InGaAlP cladding layer 44 and a p-GaAs contact layer 45 are formed on the InGaAlP active layer 43 .
  • a p-side electrode 47 is formed on the p-GaAs contact layer 45
  • an n-side electrode 48 is formed on the back side of the n-GaP substrate 40 .
  • the surfaces of the n-InGaAlP cladding layer 42 , the InGaAlP active layer 43 , the p-InGaAlP cladding layer 44 , and the p-GaAs contact layer 45 are covered with an insulating film 46 , except for a region where the p-side electrode 47 is formed.
  • the p-side electrode 47 includes an AuZn layer 49 , an Mo layer 50 , an Al layer 51 , a Ti layer 52 , and an Au layer 53 .
  • the AuZn layer 49 forms an ohmic contact with the p-GaAs contact layer 45 .
  • the Mo layer 50 is a barrier layer having a function of preventing interdiffusion of metal atoms.
  • the Al layer 51 is a high-reflection layer having a function of reflecting light generated in the element at high reflectance.
  • the Ti layer 52 is a barrier layer having a function of preventing interdiffusion of metal atoms.
  • the Au layer 53 is an overcoat layer for improving the contact with a submount.
  • this light emitting element shown in FIG. 16 is mounted on a submount 13 by flip chip bonding, with the back side of the n-GaP substrate 40 facing up.
  • the n-side electrode 48 is formed on the back side of the n-GaP substrate 40 . That is, this n-side electrode 48 is formed on the surface different from the surface on which the p-side electrode 47 is formed. Hence, the n-side electrode and the lead frame are electrically connected directly by a bonding wire. However, the n-side electrode 48 and the p-side electrode 47 can also be formed on the same surface.
  • the barrier layer e.g., an Mo layer
  • the ohmic layer e.g., an AuZn layer
  • the high-reflection layer e.g., an Al layer
  • a method of fabricating the p-side electrode 47 of the light emitting element according to the present invention is the same as the method of fabricating the p-side electrode of the light emitting element shown in FIG. 8, so a detailed description thereof will be omitted.
  • FIG. 17 shows the second embodiment of the light emitting element of the present invention.
  • This light emitting element relates to a GaN violet type LED.
  • the characteristic feature of the light emitting element according to this embodiment is the structure of a p-side electrode 26 .
  • An Ni layer 32 as an ohmic layer in contact with a p-GaN layer 24 is made up of a plurality of dots (islands) arranged into arrays.
  • An Mo layer 33 as a barrier layer is formed on the Ni layer 32 and the p-GaN layer 24 . Accordingly, the p-GaN layer 24 is in contact with both the Ni layer 32 and the Mo layer 32 .
  • the ohmic layer (Ni layer) for forming an ohmic contact with the p-GaN layer does not cover the entire surface of the p-side electrode; this ohmic layer partially covers the p-side electrode as, e.g., a plurality of dots (islands) arranged into arrays. Therefore, in a region where this ohmic layer exists, an ohmic contact is formed between the p-side electrode and the p-GaN layer. In a region where the ohmic layer does not exist, only the barrier layer is formed between the p-GaN layer and the Al layer as a high-reflection layer, thereby shortening the distance between the two layers.
  • the ohmic layer can be formed using materials such as Ni, Pt, Mg, Zn, Be, Ag, Au, and Ge and compounds consisting primarily of these materials.
  • the barrier layer can be formed using materials such as Mo, W, Pt, Ni, Ti, Pd and V and compounds consisting primarily of these materials.
  • the ohmic layer and the barrier layer can also be formed using the same material (e.g., Ni or Pt).
  • FIG. 18 shows a modification of the light emitting element shown in FIG. 17.
  • an n-InGaAlP adhesive layer 41 and an n-InGaAlP cladding layer 42 are formed on an n-GaP substrate 40 .
  • an InGaAlP active layer 43 is formed on this n-InGaAlP cladding layer 42 .
  • a p-InGaAlP cladding layer 44 and a p-GaAs contact layer 45 are formed on the InGaAlP active layer 43 .
  • a p-side electrode 47 is formed on the p-GaAs contact layer 45
  • an n-side electrode 48 is formed on the back side of the n-GaP substrate 40 .
  • the surfaces of the n-InGaAlP cladding layer 42 , the InGaAlP active layer 43 , the p-InGaAlP cladding layer 44 , and the p-GaAs contact layer 45 are covered with an insulating film 46 , except for a region where the p-side electrode 47 is formed.
  • the p-side electrode 47 includes an AuZn layer 49 , an Mo layer 50 , an Al layer 51 , a Ti layer 52 , and an Au layer 53 .
  • the AuZn layer 49 forms an ohmic contact with the p-GaAs contact layer 45 .
  • the Mo layer 50 is a barrier layer having a function of preventing interdiffusion of metal atoms.
  • the Al layer 51 is a high-reflection layer having a function of reflecting light generated in the element at high reflectance.
  • the Ti layer 52 is a barrier layer having a function of preventing interdiffusion of metal atoms.
  • the Au layer 53 is an overcoat layer for improving the contact with a submount.
  • the AuZn layer 49 as an ohmic layer is made up of a plurality of dots (islands).
  • this light emitting element shown in FIG. 18 is mounted on a submount 13 by flip chip bonding, with the back side of the n-GaP substrate 40 facing up.
  • the n-side electrode 48 is formed on the back side of the n-GaP substrate 40 . That is, this n-side electrode 48 is formed on the surface different from the surface on which the p-side electrode 47 is formed. Hence, the n-side electrode and the lead frame are electrically connected directly by a bonding wire. However, the n-side electrode 48 and the p-side electrode 47 can also be formed on the same surface.
  • the barrier layer e.g., an Mo layer
  • the ohmic layer e.g., an AuZn layer
  • the high-reflection layer e.g., an Al layer
  • FIG. 19 shows the third embodiment of the light emitting element of the present invention.
  • this light emitting layer 55 includes, as shown in FIG. 8, an InGaN active layer 22 on the n-GaN layer 21 , a p-AlGaN cladding layer 23 on the InGaN active layer 22 , and a p-GaN layer 24 on the p-AlGaN cladding layer 23 .
  • a p-side electrode 26 is formed on the light emitting layer 55 .
  • this p-side electrode 26 includes, as shown in FIG. 8, an ohmic layer 32 , a barrier layer 33 , a high-reflection layer 34 , a barrier layer 35 , and an overcoat layer 36 .
  • the p-side electrode 26 is placed in a central portion on the upper surface of the light emitting layer 55 . Also, an n-side electrode 25 is placed at the edge on the upper surface of the n-GaN layer 21 to surround the light emitting layer 55 .
  • the LED shown in FIG. 7 is completed by mounting the above light emitting element on a lead frame by using a submount and covering the light emitting element with an epoxy resin.
  • This light emitting element can achieve the following effects in addition to the effects of the light emitting elements of the aforementioned first and second embodiments.
  • the p-side electrode is positioned in the central portion of the chip, the light emitting element is readily aligned when mounted on the submount. This can facilitate the fabrication of the LED and thereby improve the throughput.
  • the n-side electrode surrounds the light emitting layer, an electric current flowing from the p-side to the n-side electrode is evenly injected into the active layer. Hence, the light emitting layer can generate light with high efficiency.
  • FIG. 20 shows a modification of the light emitting element shown in FIG. 19.
  • the characteristic feature of the light emitting element of this embodiment is that the shape of a light emitting layer 55 is different from that of the light emitting element shown in FIG. 19.
  • the light emitting layer 55 is formed in a wide region including a region immediately below the p-side electrode 26 , and the shape of this light emitting layer 55 is a square similar to that of the chip.
  • the light emitting layer 55 is formed only in a region immediately below the p-side electrode 26 and a narrow region surrounding that region, and the shape of this light emitting layer 55 is a circle similar to that of the p-side electrode.
  • the light emitting region is limited. Therefore, the light emitting element of this embodiment can be used as a signal source of an optical fiber system or in a system required to operate at high speed.
  • the shapes of the n-side electrode 25 , the p-side electrode 26 , and the light emitting element 55 can be variously changed.
  • the p-side electrode 26 can be a square, or the n-side electrode 25 , the p-side electrode 26 , and the light emitting layer 55 can take shapes other than a circle and square.
  • the light emitting element according to the third embodiment described above is applicable to, e.g., a GaN light emitting element, GaAs light emitting element, and GaP light emitting element.
  • This light emitting element is also applicable to an LED which uses a conductive substrate instead of a sapphire substrate.
  • FIG. 21 shows the fourth embodiment of the light emitting element of the present invention.
  • the light emitting element of this embodiment is applied to a GaAs light emitting element and GaP light emitting element, and generates red light having a wavelength of, e.g., 620 nm.
  • a p-InGaAlP adhesive layer 61 and a p-InAlP cladding layer 62 are formed on a p-GaP substrate 60 .
  • An InGaAlP active layer 63 is formed on the p-InAlP cladding layer 62 .
  • An n-type InAlP cladding layer 64 is formed on the InGaAlP active layer 63 , and an n-InGaAlP window layer 65 is formed on this n-type InAlP cladding layer 64 .
  • an n-GaAs contact layer 66 is formed on the n-InGaAlP window layer 65
  • an n-side electrode 67 is formed on the n-GaAs contact layer 66
  • a p-side electrode 68 and a light reflecting film 69 are formed on the back side of the p-GaP substrate 60 .
  • MO-CVD is used to form an etching stopper (e.g., InGaP) 71 , an n-GaAs contact layer 66 about 0.1 ⁇ m thick, an n-In 0.5 Ga 0.15 Al 0.35 P window layer 65 about 0.5 ⁇ m thick, and an n-In 0.5 Al 0.5 P cladding layer 64 about 1 ⁇ m thick in this order on an n-GaAs substrate 70 .
  • etching stopper e.g., InGaP
  • n-GaAs contact layer 66 about 0.1 ⁇ m thick
  • an n-In 0.5 Ga 0.15 Al 0.35 P window layer 65 about 0.5 ⁇ m thick
  • an n-In 0.5 Al 0.5 P cladding layer 64 about 1 ⁇ m thick in this order on an n-GaAs substrate 70 .
  • MO-CVD or MBE is used to form an undoped In 0.5 Ga 0.1 Al 0.4 P active layer 63 about 0.2 ⁇ m thick on the n-InAlP cladding layer 64 , and form a p-In 0.5 Al 0.5 P cladding layer 62 about 1 ⁇ m thick and a p-In 0.5 Ga 0.15 Al 0.35 P adhesive layer 61 about 0.05 ⁇ m thick on the undoped InGaAlP active layer 63 .
  • Examples of the gallium material are triethylgallium (TEG: Ga(C 2 H 5 ) 3 ) and trimethylgallium (TMG: Ga(CH 3 ) 3 ).
  • Examples of the aluminum material are triethylaluminum (TEA: Al(C 2 H 5 ) 3 ) and trimethylaluminum (TMA: [Al(CH 3 ) 3 ] 2 ).
  • Examples of the indium material are triethylindium (TEI: In(C 2 H 5 ) 3 ) and trimethylindium (TMI: In(CH 3 ) 3 ).
  • An example of the phosphorous material is tertiary-butylphosphine (TBP: C 4 H 9 PH 2 ).
  • n-impurity Si, Te, or the like is used.
  • p-impurity Zn, Be, or the like is used.
  • a p-GaP substrate 60 about 200 ⁇ m thick is adhered onto the p-InGaAlP adhesive layer 61 by thermal contact bonding. Before this adhesion, the adhesion surfaces of the p-InGaAlP adhesive layer 61 and the p-GaP substrate 60 are well cleaned.
  • the n-GaAs substrate 70 is removed by etching.
  • the n-GaAs contact layer 66 is patterned by photolithography and etching.
  • an n-side electrode 67 is formed on the n-GaAs contact layer 66 , and a p-side electrode 68 and a light reflecting layer (e.g., Au) 69 are formed on the back side of the p-GaP substrate 70 . In this manner, the light emitting element shown in FIG. 21 is obtained.
  • a light reflecting layer e.g., Au
  • the lamp type LED is completed by mounting the light emitting element shown in FIG. 21 on a lead frame and covering this light emitting element with an epoxy resin.
  • This LED emits red light when an electric current flowing from the p-side to the n-side electrode is injected into the InGaAlP active layer 63 .
  • the red light having a wavelength of 620 nm generated in the InGaAlP active layer 63 light heading to the n-InAlP cladding layer 64 and the n-InGaAlP window layer 65 is directly emitted to the outside of the chip.
  • the red light having a wavelength of 620 nm generated in the InGaAlP active layer 63 light heading to the p-GaP substrate 60 is transmitted through the transparent p-GaN substrate 60 and reaches the p-side electrode 68 and the light reflecting layer 69 . This light is reflected by the light reflecting layer 69 . The reflected light reaches the n-InAlP cladding layer 64 and the n-InGaAlP window layer 65 and is emitted to the outside of the chip.
  • This light emitting element is applied to a GaAs or GaP light emitting element having a flip chip structure. Also, the light emitting element of this embodiment can reduce the loss produced in the alloy layer between the transparent substrate and the electrode, because the light reflecting layer is formed in a portion of the back side of the transparent substrate. As a consequence, in a region where the light reflecting layer is present, light can be efficiently reflected and emitted to the outside of the chip.
  • the material of this light reflecting layer is, e.g., Au. This is so because Au has high reflectance to light having a wavelength of 620 nm, which is generated in the InGaAlP active layer.
  • Table 1 shows the values of reflectance R and thermal conductivity k of metal materials.
  • the characteristics required for a light reflecting layer are high reflectance and high thermal conductivity.
  • a lowering of the emission efficiency by heat is significant. Therefore, efficiently radiating heat generated near the active layer to the outside of the element is important.
  • a material having high reflectance and high thermal conductivity e.g., Au, Ag, Cu, or Al, is used as a light reflecting layer of a light emitting element.
  • the area of the p-side electrode 68 and the area of the light reflecting layer 69 have the following relationship. That is, when the area of the p-side electrode 68 is made larger than that of the light reflecting layer 69 , the contact resistance decreases, but the light reflection efficiency lowers; when the area of the light reflecting layer 69 is made larger than that of the p-side electrode 68 , the light reflection efficiency rises, but the contact resistance increases.
  • the area ratio of the p-side electrode 68 to the light reflecting layer 69 is set at, e.g., 1:1. However, this ratio can be appropriately changed in accordance with the specification of a light emitting element. For example, in a light emitting element in which a rise of the contact resistance is of no problem, the area of the light reflecting layer 69 is made larger than that of the p-side electrode 68 to raise the light reflection efficiency.
  • FIG. 26 shows a modification of the light emitting element shown in FIG. 21.
  • the light emitting element of this modification is characterized in that the structure of a light reflecting layer is different from that of the light emitting element shown in FIG. 21.
  • a light reflecting layer 69 on the back side of a p-GaP substrate 60 is composed of an Si layer 72 and an Al 2 O 3 layer 73 .
  • the thicknesses of the Si layer 72 and the A 1 2 O 3 layer are so set as to be ⁇ /4n (n indicates the refractive indices of Si and Al 2 O 3 with respect to the wavelength of light generated in the active layer) with respect to a wavelength ⁇ of light generated in the active layer.
  • the Si layer 72 and the Al 2 O 3 73 have a large refractive index difference, and the absorption coefficient of the Si layer 72 having a high refractive index is small. Therefore, the light reflecting layer 69 can achieve high reflectance.
  • the Al 2 O 3 layer 68 having a low refractive index has small thermal conductivity and hence deteriorates the thermal characteristics of the element.
  • FIG. 27 shows the relationship between the electric current and the optical output of the light emitting element shown in FIG. 21.
  • line ⁇ circle over ( 1 ) ⁇ corresponds to the light emitting element shown in FIG. 21; line ⁇ circle over ( 2 ) ⁇ , the light emitting element shown in FIG. 26; and line ⁇ circle over ( 3 ) ⁇ , a conventional light emitting element.
  • the light emitting element shown in FIG. 21 is most superior in optical output and durability.
  • the optical output of the light emitting element shown in FIG. 26 saturates when the injection current increases under the influence of low thermal conductivity of Al 2 O 3 .
  • the optical output of this light emitting element shown in FIG. 26 is higher than that of the conventional light emitting element.
  • the characteristic of the light emitting element shown in FIG. 26 is substantially the same as that of the light emitting element shown in FIG. 21. Accordingly, it is well significant to use the light emitting element of this modification as an LED.
  • FIG. 28 shows the fifth embodiment of the light emitting element of the present invention.
  • This embodiment relates to a light emitting element which generates 620-nm red light in a GaAs light emitting element and a GaP light emitting element.
  • a light emitting layer 81 is formed on a portion of an n-GaP substrate 80 .
  • This light emitting layer 81 includes an n-InGaAlP contact layer 82 , an n-InAlP cladding layer 83 , an InGaAlP active layer 84 , a p-InAlP cladding layer 85 , and a p-InGaAlP contact layer 86 .
  • An undoped GaP current limiting layer 87 is formed on the other portion (a region where the light emitting layer 81 is not formed) of the n-GaP substrate 80 .
  • a p-GaP layer 88 is formed on the light emitting layer 81 and the undoped GaP current limiting layer 87 .
  • a p-side electrode 89 is formed on the p-GaP layer 88 .
  • An n-side electrode 90 and a light reflecting layer 91 are formed on the back side of the n-GaP substrate 80 .
  • n-side electrode 90 is positioned immediately below the light emitting layer 81 .
  • MO-CVD is used to form an n-In 0.5 Ga 0.15 Al 0.35 P contact layer 82 , an n-In 0.5 Al 0.5 P cladding layer 83 , an In 0.5 Ga 0.1 Al 0.4 P active layer 84 , a p-In 0.5 Al 0.5 P cladding layer 85 , and a p-In 0.5 Ga 0.15 Al 0.35 P contact layer 86 in this order on an n-GaAs substrate 92 .
  • MO-CVD is used to form an undoped GaAs protective layer 93 and an SiO 2 mask layer 94 in this order on the p-In 0.5 Ga 0.15 Al 0.35 P contact layer 86 .
  • the SiO 2 mask layer 94 is patterned by photolithography and wet etching. This SiO 2 mask layer 94 is used as a mask to etch the GaAs protective layer 93 , the p-In 0.5 Ga 0.15 Al 0.35 P contact layer 86 , the p-In 0.5 Al 0.5 P cladding layer 85 , the In 0.5 Ga 0.1 Al 0.4 P active layer 84 , the n-In 0.5 Al 0.5 P cladding layer 83 , and the n-In 0.5 Ga 0.15 Al 0.35 P contact layer 82 by RIE, thereby forming a ridge-shaped light emitting layer 81 .
  • an undoped GaP current limiting layer 87 is formed on the n-GaAs substrate 92 by CVD.
  • a p-GaP layer 88 is formed on the light emitting layer 81 and the undoped GaP current limiting layer 87 by CVD. After that, the n-GaAs substrate 92 is entirely etched away to form a device as shown in FIG. 33.
  • an n-GaP substrate 80 is bonded to the device shown in FIG. 33.
  • a p-side electrode 89 is formed on the p-GaP layer 88 , and an n-side electrode 90 and a light reflecting layer 91 are formed on the back side of the n-GaP substrate 80 .
  • the light emitting layer 81 is positioned in a central portion of the n-GaP substrate 80 (or the chip) and surrounded by the undoped GaP current limiting layer 87 .
  • red light generated in the InGaAlP active layer 84 of this light emitting element light traveling to the p-side electrode is emitted to the outside of the chip through the p-InAlP cladding layer 85 , the p-InGaAlP contact layer 86 , and the p-GaP layer 88 .
  • red light generated in the InGaAlP active layer 84 light heading to the n-GaP substrate 80 is reflected by the light reflecting layer 91 through the n-GaP substrate 80 which is a transparent substrate. This reflected light travels to the p-side electrode and is emitted to the outside of the chip.
  • the n-side electrode 90 is positioned immediately below the InGaAlP active layer 83 , and the light reflecting layer 91 is positioned immediately below the GaP current limiting layer 87 . That is, light heading to the n-GaP substrate 80 is reflected by the light reflecting layer 91 . Consequently, the reflected light is emitted to the outside of the chip through the GaP current limiting layer 87 whose bandgap energy is larger than its emission energy, without passing through the light emitting layer 81 .
  • the light emitting element of this embodiment can achieve sufficiently high light extraction efficiency.
  • the optical output is 1.4 times (about 20 cd) that of a conventional light emitting element.
  • the electrode structure of the p-side electrode includes at least an ohmic layer for an ohmic contact, a barrier layer for preventing diffusion of metal impurities, and a high-reflection layer for reflecting light generated in the active layer with high reflectance.
  • the barrier layer is made of a high-melting material and prevents interdiffusion of metal atoms caused by heat between the ohmic layer and the high-reflection layer. Also, since the thicknesses of the ohmic layer and barrier layer are made as small as possible, the light absorption loss in these ohmic layer and barrier layer can be minimized. Therefore, in this p-side electrode it is possible to realize an ohmic contact and high light reflectance at the same time and suppress a rise of the operating voltage by heat.
  • the light emitting element and the semiconductor device using the same according to the present invention can realize high reliability and high performance.
  • the ohmic layer is made up of a plurality of dots (islands) arranged into arrays, it is possible to realize not only an ohmic contact but also high light extraction efficiency by high reflectance in a region where no ohmic layer exists, because absorption and loss of light can be reduced by the amount of ohmic layer.
  • each of the fourth and fifth embodiments of the light emitting element of the present invention light generated in the active layer and traveling to the substrate is reflected by the light reflecting layer, so the entire light is extracted to the outside of the chip from the surface of the p-GaP layer on the p-side electrode side.
  • the electrode and the light reflecting layer are alternately arranged on the back side of the substrate. In a region where the electrode is present, scattering and absorption of light occur; in a region where the light reflecting layer is present, light is reflected with high efficiency. Accordingly, the light emitting element of the present invention can increase the light extraction efficiency and improve the performance of both the element and the semiconductor device using the element, compared to conventional light emitting elements.
  • the light emitting layer is formed in the shape of a ridge and surrounded by a transparent material (undoped GaP).
  • a transparent material undoped GaP
  • an electrode is placed immediately below the light emitting layer, and a light reflecting layer is placed immediately below the transparent material. Consequently, it is possible to prevent an event in which light reflected by the light reflecting layer is again absorbed in the light emitting layer, and to increase the light extraction efficiency.
  • the electrode structure of the present invention can realize an ohmic contact and high light reflectance at the same time, and can also prevent interdiffusion of metal atoms between a plurality of layers forming the electrode. This makes it possible to increase the external quantum efficiency of a light emitting element, lower the operating voltage, and improve the reliability.

Abstract

An InGaN active layer is formed on a sapphire substrate. A p-side electrode is formed on the InGaN active layer to supply an electric current to this InGaN active layer. The p-side electrode includes {circle over (1)} an Ni layer for forming an ohmic contact with a p-GaN layer, {circle over (2)} an Mo layer having a barrier function of preventing diffusion of impurities, {circle over (3)} an Al layer as a high-reflection electrode, {circle over (4)} a Ti layer having a barrier function, and {circle over (5)} an Au layer for improving the contact with a submount on a lead frame. The p-side electrode having this five-layered structure realizes an ohmic contact and high reflectance at the same time.

Description

    CROSS-REFERENCE TO RELATED APPLICATIONS
  • This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-200298, filed Jun. 30, 2000, the entire contents of which are incorporated herein by reference. [0001]
  • BACKGROUND OF THE INVENTION
  • 1. Field of the Invention [0002]
  • The present invention relates to a light emitting element and, more particularly, to the electrode structure of a light emitting element. [0003]
  • 2. Description of the Related Art [0004]
  • The recent progress of light emitting elements is remarkable. In particular, small-sized, low-power-consumption, high-reliability light emitting diodes (LEDs) are developed and extensively used as display light sources. [0005]
  • Red, orange, yellow, and green LEDs currently put to practical use are made of group III-V compound semiconductors using As and P as group V elements, e.g., AlGaAs, GaAlP, GaP, and InGaAlP. On the other hand, green, blue, and ultraviolet LEDs are made of compound semiconductors such as GaN. In this way, LEDS having high emission intensity are realized. [0006]
  • When the luminance of these LEDS is increased, applications such as outdoor display devices and communication light sources are presumably greatly extended. [0007]
  • FIG. 1 shows the structure of a conventional violet LED. [0008]
  • A [0009] light emitting element 110 for emitting violet light is bonded on a lead frame 120 by silver paste 130. The p- and n-electrodes of this light emitting element 110 are connected to the lead frame 120 by bonding wires 150. The light emitting element 110 is covered with an epoxy resin 180.
  • FIG. 2 shows the light emitting element shown in FIG. 1. [0010]
  • On a sapphire (Al[0011] 2O3) substrate 200, an n-GaN layer 210 and a p-GaN layer 220 are formed. The n-GaN layer 210 has a recess. Since the p-GaN layer 220 is not present on this recess, the n-GaN layer 210 is exposed in this recess of the n-GaN layer 210.
  • An n-[0012] side electrode 230 is formed on the recess of the n-GaN layer 210. A transparent electrode 240 having properties of transmitting light is formed on the p-GaN layer 220. In addition, a bonding electrode 250 for wire bonding is formed on the p-GaN layer 220.
  • When a voltage is applied between the two [0013] lead frames 120 in the LED shown in FIGS. 1 and 2, an electric current is injected into the p-GaN layer 220 from the bonding electrode 250 and the transparent electrode 240. This electric current flows from the p-GaN layer 220 to the n-GaN layer 210.
  • In the boundary (p-n junction) between the p-[0014] GaN layer 220 and the n-GaN layer 210, light having energy hν (h: Planck's constant, ν=c/λ, c: velocity of light, λ: wavelength) is generated when the electric current flows. This light is emitted upward from the transparent electrode 240.
  • In the [0015] transparent electrode 240, however, the light transmittance and the conductivity have a relationship of trade-off.
  • That is, to increase the light transmittance, the thickness of the electrode need only be decreased. However, if the electrode thickness is decreased, the conductivity lowers. When the conductivity lowers, no electric current can be supplied to the whole p-n junction any longer, and this decreases the light generation efficiency. Also, to increase the conductivity, the thickness of the electrode need only be increased. However, if the electrode thickness is increased, the light transmittance lowers. When the light transmittance lowers, light generated in the p-n junction cannot be efficiently extracted to the outside of the chip. [0016]
  • As a technology by which this problem is solved, a technology of emitting light toward the [0017] sapphire substrate 200 is known.
  • FIG. 3 shows a light emitting element using this technology. [0018]
  • Since this light emitting element is bonded on a lead frame by flip chip bonding, an LED having this light emitting element is called a flip chip type LED. [0019]
  • A high-[0020] reflectance electrode 260 is formed on p-GaN 220. Of light generated in the p-n junction, light traveling to a sapphire substrate 200 is directly emitted to the outside of the chip. Of light generated in the p-n junction, light heading to the electrode 260 is reflected by this electrode 260. The reflected light travels to the sapphire substrate 200 and is emitted to the outside of the chip.
  • The [0021] sapphire substrate 200 will be described below.
  • When InGaN is used as an active layer, an LED currently put to practical use emits light within the range of blue to green. The bandgap of the [0022] sapphire substrate 200 is approximately 3.39 eV (wavelength λ≈365 nm) at room temperature (300 K). That is, the sapphire substrate 200 has properties of transmitting light within the range of blue to green (the wavelength λ is approximately 400 to 550 nm).
  • A flip chip type LED is very effective as a technology of extracting light to the outside of the chip with high efficiency, but also has a problem. [0023]
  • That is, it is generally difficult to form an ohmic contact with the p-[0024] GaN 220 when the high-reflectance electrode 260 is used. This ohmic contact is an essential technology to reduce the contact resistance between the electrode 260 and the p-GaN 220 and thereby improve the performance of the element.
  • Conventionally, therefore, the [0025] electrode 260 is given a two-layered structure including an ohmic layer for forming an ohmic contact and a high-reflection layer having high reflectance. The ohmic layer improves the performance and the high-reflection layer increases the light emission efficiency at the same time.
  • Unfortunately, the ohmic layer obtains an ohmic contact by interdiffusion of metal atoms between this ohmic layer and the p-[0026] GaN 220, so these metal atoms naturally diffuse from the ohmic layer to the high-reflection layer. Since this diffusion lowers the performance and reliability of the light emitting element, it must be eliminated.
  • FIG. 4 shows an LED made of group III-V compound semiconductors having As and P as group V elements. [0027]
  • This LED emits light within the range of red to green. [0028]
  • On an n-[0029] GaAs substrate 300, an n-GaAs buffer layer 310 and an n-InGaAlP cladding layer 320 are formed. On this n-InGaAlP cladding layer 320, an InGaAlP active layer 330, a p-InGaAlP cladding layer 340, and a p-AlGaAs current diffusing layer 350 are formed.
  • On the p-AlGaAs current diffusing [0030] layer 350, a p-GaAs contact layer 360 and a p-side electrode 370 are formed. An n-side electrode 380 is formed on the back side of the n-GaAs substrate 300.
  • In a light emitting element made of group III-V compound semiconductors (e.g., GaAs, AlGaAS, and InGaAlP) having As and P as group V elements, a sufficiently thick current diffusing layer (the AlGaAs current diffusing layer [0031] 350) is formed on a p-semiconductor layer without forming any transparent electrode on a p-semiconductor layer (the InGaAlP cladding layer 340). This sufficiently thick current diffusing layer has a function of evenly injecting an electric current into the entire InGaAlP active layer 330. Since the AlGaAs current diffusing layer 350 increases the light generation efficiency in the vicinity of the active layer, satisfactory optical power can be assured.
  • In the light emitting element shown in FIG. 4, an electric current given to the p-[0032] side electrode 370 is injected into the InGaAlP active layer 330 via the p-AlGaAs current diffusing layer 350. Light generated near the InGaAlP active layer 330 is emitted upward from the p-AlGaAs current diffusing layer 350 except for a region where the p-side electrode 370 exists.
  • The film thickness, however, of the [0033] current diffusing layer 350 must be increased to well diffuse the electric current for the reason explained below. That is, if the film thickness is small, the electric current is not diffused but injected only into the active layer 330 immediately below the p-side electrode 370. Consequently, most of the light generated near the active layer 330 is interrupted by the p-side electrode 370.
  • In the fabrication of an LED and an LD (Laser Diode), MO-CVD (Metal Organic-Chemical Vapor Deposition) or MBE (Molecular Beam Epitaxy) is often used as a crystal growth method. This is so because these methods can well control the film thickness in the formation of a thin film and thereby can form a high-quality film. [0034]
  • Unfortunately, these methods have the problem that they are inappropriate to form sufficiently thick films. That is, when MO-CVD or MBE is used, a very long time is required to form the sufficiently thick [0035] current diffusing layer 350 used in the light emitting element shown in FIG. 4. This worsens the productivity.
  • Additionally, in the light emitting element shown in FIG. 4, the light generated in the InGaAlP [0036] active layer 330 is absorbed by the n-GaAs substrate 300. This lowers the light extraction efficiency of the light emitting element shown in FIG. 4.
  • As a method of solving this problem of light absorption by the [0037] GaAs substrate 300, it is possible to form a flip chip type LED described earlier. However, the GaAs substrate 300 is opaque. Accordingly, a device from which this GaAs substrate 300 is removed is prepared, and a transparent substrate which transmits light is bonded to this device.
  • FIG. 5 shows a light emitting element using this technology. [0038]
  • On a p-[0039] GaP substrate 400, a p-InGaAlP adhesive layer 410 and a p-InGaAlP cladding layer 420 are formed. An InGaAlP active layer 430 is formed on the p-InGaAlP cladding layer 420. On this InGaAlP active layer 430, an n-InGaAlP cladding layer 440 and an n-AlGaAs window layer 450 are formed.
  • In addition, an [0040] electrode 460 having high reflectance and an n-side electrode 470 are formed on the AlGaAs window layer 450. A p-side electrode 480 is formed on the back side of the p-GaP substrate 400.
  • Note that the [0041] GaP substrate 400 has a bandgap of 2.26 eV (λ≈548 nm) at room temperature and is transparent to red light.
  • With this arrangement, of light generated in the InGaAlP [0042] active layer 430, light traveling to the p-GaP substrate 400 is directly emitted to the outside of the chip. Also, of light generated in the InGaAlP active layer 430, light heading to the electrode 460 is reflected by this electrode 460 having high reflectance. This reflected light travels to the p-GaP substrate 400 and is emitted to the outside of the chip.
  • In the [0043] electrode 460, however, it is difficult to achieve an ohmic contact and high reflectance at the same time by the use of a single material. Therefore, this electrode 460 is given a two-layered structure including an ohmic layer and high-reflection layer. In this case, as described previously, the interdiffusion of metals between the ohmic layer and the high-reflection layer is a problem.
  • FIG. 6 shows a light emitting element using the technology of bonding a GaP substrate to a device from which a GaAs substrate is removed. [0044]
  • In this technology, light is reflected by the bonding surface between a [0045] GaP substrate 400 and a p-side substrate 480 and extracted upward from an AlGaAs window layer 450.
  • Compared to the light emitting element shown in FIG. 5, this light emitting element shown in FIG. 6 is characterized by having no high-reflectance electrode on the n-[0046] AlGaAs window layer 450. In this structure, however, an alloy layer produced in the boundary between the p-GaP substrate 400 and the p-side electrode 480 scatters and absorbs light. This makes effective extraction of light to the outside of the chip difficult.
  • As described above, light is extracted from the conventional light emitting elements by the two methods: extraction from a light emitting layer, and extraction from a substrate. [0047]
  • When, however, a transparent electrode for diffusing an electric current is formed on the entire surface of a light emitting layer and light is extracted from this light emitting layer, the trade-off between the light transmittance and the conductivity is a problem. That is, if the thickness of the transparent electrode is decreased to increase the light transmittance, the conductivity lowers; if the thickness of the transparent electrode is increased to increase the conductivity, the light transmittance lowers. [0048]
  • In a structure in which an n-side electrode is formed on a portion of a light emitting layer and a thick current diffusing layer is formed below this n-side electrode, if light is to be extracted from the light emitting layer by reflecting it by a p-side electrode formed on the back side of a GaP substrate, this light is scattered and absorbed by the bonding surface between the GaP substrate and the p-side electrode. This worsens the light extraction efficiency. [0049]
  • Also, in a structure in which an n-side electrode is formed on a portion of a light emitting layer and a thick current diffusing layer is formed below this n-side electrode, if light is to be extracted from the substrate by reflecting it by the light emitting layer, the n-side electrode on the light emitting layer must have high reflectance. This high-reflectance n-side electrode can be realized by using a two-layered structure including an ohmic layer and high-reflection layer as an electrode structure. In this case, however, the interdiffusion of metals between the ohmic layer and the high-reflection layer is a problem. [0050]
  • BRIEF SUMMARY OF THE INVENTION
  • It is an object of the present invention to provide a light emitting element electrode structure capable of simultaneously achieving an ohmic contact and high reflectance and preventing interdiffusion of metals, thereby improving the performance and reliability of the light emitting element and lowering the operating voltage of the element. It is another object of the present invention to suppress scattering and absorption of light in an electrode portion of a light emitting element, thereby increasing the light emission efficiency. [0051]
  • A light emitting element of the present invention comprises a substrate, a light emitting element formed on the substrate to emit light, and a first electrode contacting the light emitting layer. This first electrode includes an ohmic layer in ohmic contact with the light emitting layer, a first barrier layer formed on the ohmic layer to prevent diffusion of metal atoms, and a light reflecting layer formed on the first barrier layer to reflect light. [0052]
  • Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.[0053]
  • BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
  • The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. [0054]
  • FIG. 1 is a view showing a conventional LED; [0055]
  • FIG. 2 is a view showing the first example of a conventional light emitting element; [0056]
  • FIG. 3 is a view showing the second example of a conventional light emitting element; [0057]
  • FIG. 4 is a view showing the third example of a conventional light emitting element; [0058]
  • FIG. 5 is a view showing the fourth example of a conventional light emitting element; [0059]
  • FIG. 6 is a view showing the fifth example of a conventional light emitting element; [0060]
  • FIG. 7 is a view showing an LED of the present invention; [0061]
  • FIG. 8 is a view showing the first embodiment of a light emitting element of the present invention; [0062]
  • FIG. 9 is a view showing one step of a manufacturing method of the present invention; [0063]
  • FIG. 10 is a view showing one step of the manufacturing method of the present invention; [0064]
  • FIG. 11 is a view showing one step of the manufacturing method of the present invention; [0065]
  • FIG. 12 is a view showing one step of the manufacturing method of the present invention; [0066]
  • FIG. 13 is a graph showing the relationship between the electric current and optical output of the light emitting element shown in FIG. 8; [0067]
  • FIG. 14 is a graph showing the relationship between the thickness and reflectance of a reflecting layer of the light emitting element shown in FIG. 8; [0068]
  • FIG. 15 is a graph showing the relationship between the thickness of reflectance of an ohmic layer of the light emitting element shown in FIG. 8; [0069]
  • FIG. 16 is a view showing a modification of the light emitting element shown in FIG. 8; [0070]
  • FIG. 17 is a view showing the second embodiment of the light emitting element of the present invention; [0071]
  • FIG. 18 is a view showing a modification of the light emitting element shown in FIG. 17; [0072]
  • FIG. 19 is a view showing the third embodiment of the light emitting element of the present invention; [0073]
  • FIG. 20 is a view showing a modification of the light emitting element shown in FIG. 19; [0074]
  • FIG. 21 is a view showing the fourth embodiment of the light emitting element of the present invention; [0075]
  • FIG. 22 is a view showing one step of a manufacturing method of the present invention; [0076]
  • FIG. 23 is a view showing one step of the manufacturing method of the present invention; [0077]
  • FIG. 24 is a view showing one step of the manufacturing method of the present invention; [0078]
  • FIG. 25 is a view showing one step of the manufacturing method of the present invention; [0079]
  • FIG. 26 is a view showing a modification of the light emitting element shown in FIG. 21; [0080]
  • FIG. 27 is a graph showing the relationship between the electric current and optical output of the light emitting element shown in FIG. 21; [0081]
  • FIG. 28 is a view showing the fifth embodiment of the light emitting element of the present invention; [0082]
  • FIG. 29 is a view showing one step of a manufacturing method of the present invention; [0083]
  • FIG. 30 is a view showing one step of the manufacturing method of the present invention; [0084]
  • FIG. 31 is a view showing one step of the manufacturing method of the present invention; [0085]
  • FIG. 32 is a view showing one step of the manufacturing method of the present invention; [0086]
  • FIG. 33 is a view showing one step of the manufacturing method of the present invention; and [0087]
  • FIG. 34 is a view showing one step of the manufacturing method of the present invention.[0088]
  • DETAILED DESCRIPTION OF THE INVENTION
  • Light emitting elements and semiconductor devices using these light emitting elements according to the present invention will be described below with reference to the accompanying drawings. [0089]
  • FIG. 7 shows a lamp type LED of the present invention. [0090]
  • A [0091] submount 13 is placed on a lead frame 12. This submount 13 is made of, e.g., a silicon substrate. On the upper surface of the submount 13, high-conductivity ohmic electrodes 14-1 and 14-2 having a thickness of about 100 μm are formed.
  • The positions of these ohmic electrodes [0092] 14-1 and 14-2 match the positions of electrodes of a light emitting element 11. The ohmic electrodes 14-1 and 14-2 are physically separated from each other, and an insulating film 19 is formed only immediately below the ohmic electrode 14-2. This ohmic electrode 14-2 is electrically connected to the lead frame 12 by a bonding wire 15. The lower surface of the submount 13 is adhered to the lead frame 12 by a conductive paste 16.
  • The [0093] light emitting element 11 for emitting violet light is placed on the submount 13. This light emitting element 11 has p- and n-side electrodes. The light emitting element 11 is bonded on the submount 13 by flip chip bonding by using AuSn 17. The light emitting element 11 is covered with an epoxy resin 18.
  • FIG. 8 shows the light emitting element shown in FIG. 7. [0094]
  • An n-[0095] GaN layer 21 is formed on a sapphire substrate 20. On this n-GaN layer 21, an InGaN active layer 22, a p-AlGaN cladding layer 23, and a p-GaN layer 24 are formed. In addition, the n-GaN layer 21 has a recess at the edge of the sapphire substrate 20. Since the InGaN active layer 22, the p-AlGaN cladding layer 23, and the p-GaN layer 24 do not exist on this recess, the n-GaN layer 21 is exposed in this recess.
  • An n-[0096] side electrode 25 is formed on the n-GaN layer 21 in the recess. A p-side electrode 26 is formed on the p-GaN layer 24. The surfaces of the n-GaN layer 21, the InGaN active layer 22, the p-AlGaN cladding layer 23, and the p-GaN layer 24 are covered with an insulating film 27, except for regions where the n-side electrode 25 and the p-side electrode 26 are formed.
  • The n-[0097] side electrode 25 has a four-layered structure. This four-layered structure includes a Ti layer 28, an Al layer 29, a Ti layer 30, and an Au layer 31 in this order from the n-GaN layer 21. The p-side electrode 26 has a five-layered structure. This five-layered structure includes an Ni layer 32, an Mo layer 33, an Al layer 34, a Ti layer 35, and an Au layer 36 in this order from the p-GaN layer 24.
  • The [0098] Ni layer 32 is an ohmic layer for achieving an ohmic contact with the p-GaN layer 24. The thickness of this Ni layer 32 is set to about 4 nm. The Mo layer 33 and the Ti layer 35 function as barrier layers for preventing diffusion of impurities. The Al layer 34 reflects light at high reflectance. The Au layer 36 functions as an overcoat electrode for improving the contact with the submount 13.
  • As shown in FIG. 7, the light emitting element shown in FIG. 8 is bonded by flip chip bonding on the [0099] submount 13 with the back side of the sapphire substrate 20 facing up.
  • In this light emitting element and the LED using the element, when a voltage is applied between the two [0100] lead frames 12 an electric current is injected into the InGaN active layer 22 from the p-side electrode 26. When this electric current is injected into the InGaN layer 22, the InGaN active layer 22 emits light. This light generated by the LED is spontaneous emission light different from induced emission light. Hence, the light generated by the InGaN layer 22 has no directivity and is radiated in every direction from the InGaN layer 22.
  • In the LED shown in FIG. 7 and the light emitting element shown in FIG. 8, light is extracted from the [0101] sapphire substrate 20.
  • That is, light traveling from the InGaN [0102] active layer 22 to the sapphire substrate 20 is output to the outside of the chip via the n-GaN layer 21 and the sapphire substrate 20 which are transparent to the wavelength of light. On the other hand, light traveling from the InGaN active layer 22 to the p-AlGaN cladding layer 23 is reflected by the Al layer 34 having high reflectance to the wavelength of light. This reflected light is output to the outside of the chip via the n-GaN layer 21 and the sapphire substrate 20.
  • In the latter case, the light generated in the [0103] InGaN layer 22 makes a round trip along the path passing through the Ni layer 32 and the Mo layer 33. Note that the Ni layer 32 and the Mo layer 33 are sufficiently thinned to have a low light scattering coefficient and a low light absorption coefficient.
  • A method of manufacturing the LED shown in FIG. 7 and the light emitting element shown in FIG. 8 will be described below. [0104]
  • First, as shown in FIG. 9, MO-CVD is used to form an undoped GaN buffer layer on a [0105] sapphire substrate 20 and form an n-GaN layer 21 on this buffer layer. Subsequently, an InGaN active layer 22 is formed on the n-GaN layer 21 by MO-CVD or MBE. This InGaN active layer 22 can have an SQW (Single Quantum Well) structure or an MQW (Multiple Quantum Well) structure. In addition, a p-AlGaN cladding layer 23 and a p-GaN layer 24 are formed on the InGaN active layer 22 by MO-CVD.
  • As shown in FIG. 10, lithography and anisotropic etching such as RIE (Reactive Ion Etching) are used to remove portions of the p-[0106] GaN layer 24, the p-AlGaN cladding layer 23, the InGaN active layer 22, and the n-GaN layer 21, thereby forming a recess in the edge of the sapphire substrate 20. After that, an insulating film 27 is formed on the surfaces of the p-GaN layer 24, the p-AlGaN cladding layer 23, the InGaN active layer 22, and the n-GaN layer 21 by CVD.
  • This recess can also be formed by isotropic etching such as wet etching, rather than by anisotropic etching such as RIE. [0107]
  • As shown in FIG. 11, lithography and wet etching are used to remove a portion of the insulating [0108] film 27 on the n-GaN layer 21. After that, a Ti layer 28 and an Al layer 29 are formed by vacuum evaporation and lift-off. Also, the structure is annealed in a nitrogen atmosphere at about 600° C. to form an ohmic contact between the n-GaN layer 21 and the Ti layer 28.
  • As shown in FIG. 12, lithography and wet etching are used to remove a portion of the insulating [0109] film 27 on the p-GaN layer 24. After that, an Ni layer 32 about 4 nm thick, an Mo layer 33 about 1 nm thick, and an Al layer 34 about 500 nm thick are formed by vacuum evaporation and lift-off.
  • If flash annealing is performed at a temperature of 400° C. to 780° C. (preferably 450° C.) for 20 sec immediately after the [0110] Ni layer 32 is formed, an ohmic contact between the p-GaN layer 24 and the Ni layer 32 can be easily formed.
  • It is, however, not particularly necessary to perform this flash annealing if no natural oxide film exists in a portion between the [0111] Ni layer 32 and the p-GaN layer 24 and if this portion is satisfactorily clean.
  • Subsequently, as shown in FIG. 8, vacuum evaporation and lift-off are used to form Ti layers [0112] 30 and 35 about 100 nm thick and Au layers 31 and 36 about 1,000 nm thick on the Al layers 29 and 34, respectively. To improve adhesion between a plurality of layers forming electrodes 25 and 26, flash annealing is performed at a temperature of about 200° C. or more (favorably about 250° C.) for 20 sec.
  • The temperature of this flash annealing is set to be lower than that of flash annealing performed in the step shown in FIG. 12, if flash annealing is performed in the step shown in FIG. 12. [0113]
  • A semiconductor element of the present invention is completed by the above method. [0114]
  • The semiconductor element manufactured by the above method is packaged to form an LED (semiconductor device) of the present invention. [0115]
  • That is, as shown in FIG. 7, the [0116] light emitting element 11 is mounted on the submount 13 having the ohmic electrodes 14-1 and 14-2 made of an Au layer about 3 μm thick by flip chip bonding. Consequently, the n-side electrode 25 is connected to the electrode 14-1 by the bump (e.g., AuSn, PbSn, AgSn) 17, and the p-side electrode 26 is connected to the electrode 14-2 by the bump 17.
  • The [0117] submount 13 on which the light emitting element 11 is mounted is adhered to the cup type lead frame 12 by using the conductive paste 16. In this state, the electrode 14-1 is electrically connected to the cup type lead frame 12. Also, the electrode 14-2 and the lead frame 12 are electrically connected by wire bonding. Furthermore, the light emitting element 11 is covered with the epoxy resin 18.
  • If the [0118] light emitting element 11 is formed using an n-GaN substrate as a conductive substrate, rather than a sapphire substrate, the n-side electrode can also be formed on the back side of this n-GaN substrate.
  • The LED of the present invention is completed by the above method. [0119]
  • In the light emitting element, the LED, and the methods of fabricating them, the p-[0120] side electrode 26 has the Ni layer 32 for forming an ohmic contact with the p-GaN layer 24, the Mo layer 33 having a barrier function of blocking impurity diffusion, and the Al layer 34 having high reflectance to light generated in the element.
  • Generally, an ohmic contact to a GaN layer is difficult to form when metals such as Al and Ag having high reflectance to visible light are used. Therefore, the p-side electrode is conventionally composed of an ohmic layer for forming an ohmic contact and a high-reflection layer for reflecting light generated in the element. [0121]
  • When an LED having this electrode structure is continuously operated, however, interdiffusion of metal atoms occurs between the ohmic layer and the high-reflection layer owing to the influence of heat. This raises the forward voltage of the light emitting diode and readily deteriorates the element. And the electrode sometimes comes off. [0122]
  • By contrast, in the present invention the barrier layer (e.g., Mo layer) [0123] 33 made of a high-melting metal is formed between the Ni layer 32 as an ohmic layer and the Al layer 34 as a high-reflection layer. This barrier layer prevents interdiffusion of metal atoms between the ohmic layer and the high-reflection layer. Accordingly, the present invention can prevent a rise of the operating voltage of the LED.
  • The ohmic layer (Ni layer [0124] 32) and the barrier layer (Mo layer 33) are made of materials substantially opaque to light generated in the element. By decreasing the thicknesses of these layers, the light reflectance of the high-reflection layer (Al layer 34) can be increased.
  • FIG. 13 shows the emission characteristic of the GaN violet type LED of the present invention. [0125]
  • This emission characteristic is represented by the relationship between the electric current injected into the LED and its optical output (emission intensity). Referring to FIG. 13, the solid line indicates the emission characteristic of the GaN violet type LED according to the present invention, and the broken line indicates that of a conventional LED. [0126]
  • As shown in FIG. 13, when the same electric current is injected into these LEDS, the optical output of the LED according to the present invention is about 1.7 times that of the conventional LED. For example, when the electric current injected into the LEDS is 20 mA (voltage 4.3 V), the optical output of the conventional LED is about 4.0 mW, whereas the optical output of the LED of the present invention is about 6.9 mW (emission wavelength λp=450 nm). [0127]
  • Also, after the LED of the present invention was operated for 1,000 hr at room temperature by using a driving current of 20 mA, the optical output reduced to about 80% of the initial value. This is a very good result compared to the conventional LED and indicates that the reliability of the LED of the present invention improved. [0128]
  • FIG. 14 shows the relationship between the thickness of the Mo layer as a barrier layer and the light reflectance of the Al layer as a high-reflection layer. [0129]
  • In this relationship, the thickness of the Ni layer as an ohmic layer is fixed to 4 nm, and the thickness of the Al layer as a high-reflection layer is fixed to 100 nm. [0130]
  • FIG. 15 shows the relationship between the thickness of the Ni layer as an ohmic layer and the Al layer as a high-reflection layer. [0131]
  • In this relationship, the thickness of the Mo layer as a barrier electrode is fixed to 1 nm, and the thickness of the Al layer as a high-reflection layer is fixed to 100 nm. [0132]
  • As shown in FIGS. 14 and 15, the light reflectance of the Al layer largely depends upon the thicknesses of the barrier layer and the ohmic layer; the smaller the thicknesses of these layers, the higher the light transmittance. In particular, the thickness of the ohmic layer into which light generated in the InGaN active layer initially enters is preferably as small as possible. For example, when this ohmic layer is made of Ni, its thickness is set to 10 nm or less. [0133]
  • The ohmic layer can be formed using materials such as Pt, Mg, Zn, Be, Ag, Au, and Ge and compounds consisting primarily of these materials, in addition to Ni. Also, the barrier layer can be formed using materials such as W, Pt, Ni, Ti, Pd and V and compounds consisting primarily of these materials, in addition to Mo. [0134]
  • These ohmic layer and barrier layer can be integrated into a single layer if they are formed using the same material (Ni or Pt). [0135]
  • In the light emitting element of the present invention, the [0136] Ti layer 35 as a barrier layer and the Au layer 36 as an overcoat layer are formed on the Al layer 34 as a high-reflection layer. Commonly, a conductor pattern of Au is written on a submount on which a light emitting element is to be mounted. A light emitting element is adhered onto this conductor pattern.
  • If, however, a high-reflection layer made of Al or Ag is brought into direct contact with the Au conductor pattern, a high-resistance layer may be formed on the bonding surface between them, or the bonding power between them weakens. [0137]
  • In the present invention, therefore, an overcoat layer made of the same material as the conductor pattern (e.g., Au) on the submount is formed, thereby preventing the generation of a high-resistance layer and increasing the bonding power between the light emitting element and the submount. [0138]
  • In addition, in the present invention the barrier layer (Ti layer [0139] 35) made of a high-melting metal is formed between the overcoat layer and the high-reflection layer. Since this barrier layer prevents diffusion of metal atoms from the overcoat layer to the high-reflection layer, the bonding power between the overcoat layer and the conductor pattern can be increased.
  • When the conductor pattern and the high-reflection layer are made of the same material, it is of course unnecessary to form a high-melting-material barrier layer between the overcoat layer and the high-reflection layer. [0140]
  • This barrier layer interposed between the overcoat layer and the high-reflection layer can be formed using materials such as W, Mo, Pt, Ni, Ti, Pd, and V and compounds consisting primarily of these materials, in addition to Ti. [0141]
  • Furthermore, in the present invention the light emitting element is not in direct contact with the lead frame but is mounted on the lead frame via the submount. In this structure, heat generated in the light emitting element is efficiently radiated via the submount. This can increase the heat radiation efficiency and improve the reliability of the LED. [0142]
  • FIG. 16 shows a modification of the light emitting element shown in FIG. 8. [0143]
  • On an n-[0144] GaP substrate 40, an n-InGaAlP adhesive layer 41 and an n-InGaAlP cladding layer 42 are formed. On this n-InGaAlP cladding layer 42, an InGaAlP active layer 43 is formed. As InGaAlP, a direct transition type band structure is used to obtain red light to green light, unlike AlGaAs for which an indirect transition type band structure is used to obtain green light.
  • On the InGaAlP [0145] active layer 43, a p-InGaAlP cladding layer 44 and a p-GaAs contact layer 45 are formed. A p-side electrode 47 is formed on the p-GaAs contact layer 45, and an n-side electrode 48 is formed on the back side of the n-GaP substrate 40. The surfaces of the n-InGaAlP cladding layer 42, the InGaAlP active layer 43, the p-InGaAlP cladding layer 44, and the p-GaAs contact layer 45 are covered with an insulating film 46, except for a region where the p-side electrode 47 is formed.
  • The p-[0146] side electrode 47 includes an AuZn layer 49, an Mo layer 50, an Al layer 51, a Ti layer 52, and an Au layer 53. The AuZn layer 49 forms an ohmic contact with the p-GaAs contact layer 45. The Mo layer 50 is a barrier layer having a function of preventing interdiffusion of metal atoms. The Al layer 51 is a high-reflection layer having a function of reflecting light generated in the element at high reflectance. The Ti layer 52 is a barrier layer having a function of preventing interdiffusion of metal atoms. The Au layer 53 is an overcoat layer for improving the contact with a submount.
  • As shown in FIG. 7, this light emitting element shown in FIG. 16 is mounted on a [0147] submount 13 by flip chip bonding, with the back side of the n-GaP substrate 40 facing up.
  • In this modification, the n-[0148] side electrode 48 is formed on the back side of the n-GaP substrate 40. That is, this n-side electrode 48 is formed on the surface different from the surface on which the p-side electrode 47 is formed. Hence, the n-side electrode and the lead frame are electrically connected directly by a bonding wire. However, the n-side electrode 48 and the p-side electrode 47 can also be formed on the same surface.
  • In this light emitting element as described above, the barrier layer (e.g., an Mo layer) made of a high-melting metal is formed between the ohmic layer (e.g., an AuZn layer) and the high-reflection layer (e.g., an Al layer). Since this barrier layer prevents interdiffusion of metal atoms between the ohmic layer and the high-reflection layer, a rise of the operating voltage of the LED can be prevented. Consequently, effects similar to those of the light emitting element shown in FIG. 8 can be obtained. [0149]
  • A method of fabricating the p-[0150] side electrode 47 of the light emitting element according to the present invention is the same as the method of fabricating the p-side electrode of the light emitting element shown in FIG. 8, so a detailed description thereof will be omitted.
  • FIG. 17 shows the second embodiment of the light emitting element of the present invention. [0151]
  • This light emitting element relates to a GaN violet type LED. [0152]
  • Compared to the light emitting element (FIG. 8) explained in the above first embodiment, the characteristic feature of the light emitting element according to this embodiment is the structure of a p-[0153] side electrode 26.
  • An [0154] Ni layer 32 as an ohmic layer in contact with a p-GaN layer 24 is made up of a plurality of dots (islands) arranged into arrays. An Mo layer 33 as a barrier layer is formed on the Ni layer 32 and the p-GaN layer 24. Accordingly, the p-GaN layer 24 is in contact with both the Ni layer 32 and the Mo layer 32.
  • Of light generated in an InGaN [0155] active layer 22, a portion of light heading to a p-AlGaN cladding layer 23 passes through the Ni layer 32 and the Mo layer 33 with low scattering and low absorption. Another portion of the light heading to the p-AlGaN cladding layer 23 passes only through the Mo layer 33 without passing through the Ni layer 32.
  • In this light emitting element as described above, the ohmic layer (Ni layer) for forming an ohmic contact with the p-GaN layer does not cover the entire surface of the p-side electrode; this ohmic layer partially covers the p-side electrode as, e.g., a plurality of dots (islands) arranged into arrays. Therefore, in a region where this ohmic layer exists, an ohmic contact is formed between the p-side electrode and the p-GaN layer. In a region where the ohmic layer does not exist, only the barrier layer is formed between the p-GaN layer and the Al layer as a high-reflection layer, thereby shortening the distance between the two layers. [0156]
  • In a region where the ohmic layer is absent, therefore, the light transmittance can be increased accordingly. As a consequence, the light extraction efficiency can be increased. [0157]
  • The ohmic layer can be formed using materials such as Ni, Pt, Mg, Zn, Be, Ag, Au, and Ge and compounds consisting primarily of these materials. The barrier layer can be formed using materials such as Mo, W, Pt, Ni, Ti, Pd and V and compounds consisting primarily of these materials. [0158]
  • The ohmic layer and the barrier layer can also be formed using the same material (e.g., Ni or Pt). [0159]
  • FIG. 18 shows a modification of the light emitting element shown in FIG. 17. [0160]
  • On an n-[0161] GaP substrate 40, an n-InGaAlP adhesive layer 41 and an n-InGaAlP cladding layer 42 are formed. On this n-InGaAlP cladding layer 42, an InGaAlP active layer 43 is formed.
  • On the InGaAlP [0162] active layer 43, a p-InGaAlP cladding layer 44 and a p-GaAs contact layer 45 are formed. A p-side electrode 47 is formed on the p-GaAs contact layer 45, and an n-side electrode 48 is formed on the back side of the n-GaP substrate 40. The surfaces of the n-InGaAlP cladding layer 42, the InGaAlP active layer 43, the p-InGaAlP cladding layer 44, and the p-GaAs contact layer 45 are covered with an insulating film 46, except for a region where the p-side electrode 47 is formed.
  • The p-[0163] side electrode 47 includes an AuZn layer 49, an Mo layer 50, an Al layer 51, a Ti layer 52, and an Au layer 53. The AuZn layer 49 forms an ohmic contact with the p-GaAs contact layer 45. The Mo layer 50 is a barrier layer having a function of preventing interdiffusion of metal atoms. The Al layer 51 is a high-reflection layer having a function of reflecting light generated in the element at high reflectance. The Ti layer 52 is a barrier layer having a function of preventing interdiffusion of metal atoms. The Au layer 53 is an overcoat layer for improving the contact with a submount.
  • The [0164] AuZn layer 49 as an ohmic layer is made up of a plurality of dots (islands).
  • As shown in FIG. 7, this light emitting element shown in FIG. 18 is mounted on a [0165] submount 13 by flip chip bonding, with the back side of the n-GaP substrate 40 facing up.
  • In this modification, the n-[0166] side electrode 48 is formed on the back side of the n-GaP substrate 40. That is, this n-side electrode 48 is formed on the surface different from the surface on which the p-side electrode 47 is formed. Hence, the n-side electrode and the lead frame are electrically connected directly by a bonding wire. However, the n-side electrode 48 and the p-side electrode 47 can also be formed on the same surface.
  • In this light emitting element as described above, the barrier layer (e.g., an Mo layer) made of a high-melting metal is formed between the ohmic layer (e.g., an AuZn layer) and the high-reflection layer (e.g., an Al layer). Since this barrier layer prevents interdiffusion of metal atoms between the ohmic layer and the high-reflection layer, a rise of the operating voltage of the LED can be prevented. Consequently, effects similar to those of the light emitting element shown in FIG. 8 can be obtained. [0167]
  • FIG. 19 shows the third embodiment of the light emitting element of the present invention. [0168]
  • On a [0169] sapphire substrate 20, an n-GaN layer 21 and a light emitting layer 55 are formed. For example, this light emitting layer 55 includes, as shown in FIG. 8, an InGaN active layer 22 on the n-GaN layer 21, a p-AlGaN cladding layer 23 on the InGaN active layer 22, and a p-GaN layer 24 on the p-AlGaN cladding layer 23.
  • A p-[0170] side electrode 26 is formed on the light emitting layer 55. For example, this p-side electrode 26 includes, as shown in FIG. 8, an ohmic layer 32, a barrier layer 33, a high-reflection layer 34, a barrier layer 35, and an overcoat layer 36.
  • The p-[0171] side electrode 26 is placed in a central portion on the upper surface of the light emitting layer 55. Also, an n-side electrode 25 is placed at the edge on the upper surface of the n-GaN layer 21 to surround the light emitting layer 55.
  • The LED shown in FIG. 7 is completed by mounting the above light emitting element on a lead frame by using a submount and covering the light emitting element with an epoxy resin. [0172]
  • This light emitting element can achieve the following effects in addition to the effects of the light emitting elements of the aforementioned first and second embodiments. [0173]
  • First, since the p-side electrode is positioned in the central portion of the chip, the light emitting element is readily aligned when mounted on the submount. This can facilitate the fabrication of the LED and thereby improve the throughput. [0174]
  • Second, since the n-side electrode surrounds the light emitting layer, an electric current flowing from the p-side to the n-side electrode is evenly injected into the active layer. Hence, the light emitting layer can generate light with high efficiency. [0175]
  • FIG. 20 shows a modification of the light emitting element shown in FIG. 19. [0176]
  • The characteristic feature of the light emitting element of this embodiment is that the shape of a [0177] light emitting layer 55 is different from that of the light emitting element shown in FIG. 19.
  • In the light emitting element shown in FIG. 19, the [0178] light emitting layer 55 is formed in a wide region including a region immediately below the p-side electrode 26, and the shape of this light emitting layer 55 is a square similar to that of the chip. By contrast, in the light emitting element shown in FIG. 20, the light emitting layer 55 is formed only in a region immediately below the p-side electrode 26 and a narrow region surrounding that region, and the shape of this light emitting layer 55 is a circle similar to that of the p-side electrode.
  • In the light emitting element of this embodiment, the light emitting region is limited. Therefore, the light emitting element of this embodiment can be used as a signal source of an optical fiber system or in a system required to operate at high speed. [0179]
  • In the light emitting elements shown in FIGS. 19 and 20, the shapes of the n-[0180] side electrode 25, the p-side electrode 26, and the light emitting element 55 can be variously changed. For example, the p-side electrode 26 can be a square, or the n-side electrode 25, the p-side electrode 26, and the light emitting layer 55 can take shapes other than a circle and square.
  • The light emitting element according to the third embodiment described above is applicable to, e.g., a GaN light emitting element, GaAs light emitting element, and GaP light emitting element. This light emitting element is also applicable to an LED which uses a conductive substrate instead of a sapphire substrate. [0181]
  • FIG. 21 shows the fourth embodiment of the light emitting element of the present invention. [0182]
  • The light emitting element of this embodiment is applied to a GaAs light emitting element and GaP light emitting element, and generates red light having a wavelength of, e.g., 620 nm. [0183]
  • On a p-[0184] GaP substrate 60, a p-InGaAlP adhesive layer 61 and a p-InAlP cladding layer 62 are formed. An InGaAlP active layer 63 is formed on the p-InAlP cladding layer 62. An n-type InAlP cladding layer 64 is formed on the InGaAlP active layer 63, and an n-InGaAlP window layer 65 is formed on this n-type InAlP cladding layer 64. Also, an n-GaAs contact layer 66 is formed on the n-InGaAlP window layer 65, and an n-side electrode 67 is formed on the n-GaAs contact layer 66. In addition, a p-side electrode 68 and a light reflecting film 69 are formed on the back side of the p-GaP substrate 60.
  • A method of manufacturing the light emitting element shown in FIG. 21 will be described below. [0185]
  • First, as shown in FIG. 22, MO-CVD is used to form an etching stopper (e.g., InGaP) [0186] 71, an n-GaAs contact layer 66 about 0.1 μm thick, an n-In0.5Ga0.15Al0.35 P window layer 65 about 0.5 μm thick, and an n-In0.5Al0.5 P cladding layer 64 about 1 μm thick in this order on an n-GaAs substrate 70.
  • Subsequently, MO-CVD or MBE is used to form an undoped In[0187] 0.5Ga0.1Al0.4P active layer 63 about 0.2 μm thick on the n-InAlP cladding layer 64, and form a p-In0.5Al0.5 P cladding layer 62 about 1 μm thick and a p-In0.5Ga0.15Al0.35 P adhesive layer 61 about 0.05 μm thick on the undoped InGaAlP active layer 63.
  • Examples of the gallium material are triethylgallium (TEG: Ga(C[0188] 2H5)3) and trimethylgallium (TMG: Ga(CH3)3). Examples of the aluminum material are triethylaluminum (TEA: Al(C2H5)3) and trimethylaluminum (TMA: [Al(CH3)3]2). Examples of the indium material are triethylindium (TEI: In(C2H5)3) and trimethylindium (TMI: In(CH3)3). An example of the phosphorous material is tertiary-butylphosphine (TBP: C4H9PH2).
  • As an n-impurity, Si, Te, or the like is used. As a p-impurity, Zn, Be, or the like is used. [0189]
  • Subsequently, as shown in FIG. 23, a p-[0190] GaP substrate 60 about 200 μm thick is adhered onto the p-InGaAlP adhesive layer 61 by thermal contact bonding. Before this adhesion, the adhesion surfaces of the p-InGaAlP adhesive layer 61 and the p-GaP substrate 60 are well cleaned.
  • Also, the n-[0191] GaAs substrate 70 is removed by etching.
  • As shown in FIG. 24, the [0192] etching stopper 71 is removed.
  • As shown in FIG. 25, the n-[0193] GaAs contact layer 66 is patterned by photolithography and etching.
  • After that, an n-[0194] side electrode 67 is formed on the n-GaAs contact layer 66, and a p-side electrode 68 and a light reflecting layer (e.g., Au) 69 are formed on the back side of the p-GaP substrate 70. In this manner, the light emitting element shown in FIG. 21 is obtained.
  • The lamp type LED is completed by mounting the light emitting element shown in FIG. 21 on a lead frame and covering this light emitting element with an epoxy resin. [0195]
  • This LED emits red light when an electric current flowing from the p-side to the n-side electrode is injected into the InGaAlP [0196] active layer 63.
  • Of the red light having a wavelength of 620 nm generated in the InGaAlP [0197] active layer 63, light heading to the n-InAlP cladding layer 64 and the n-InGaAlP window layer 65 is directly emitted to the outside of the chip. Of the red light having a wavelength of 620 nm generated in the InGaAlP active layer 63, light heading to the p-GaP substrate 60 is transmitted through the transparent p-GaN substrate 60 and reaches the p-side electrode 68 and the light reflecting layer 69. This light is reflected by the light reflecting layer 69. The reflected light reaches the n-InAlP cladding layer 64 and the n-InGaAlP window layer 65 and is emitted to the outside of the chip.
  • When the light emitting element of this embodiment was mounted in a package having an emission angle of [0198] 100 and operated by a driving current of 20 mA, the optical output rose to 1.2 times (17 cd) that of a conventional light emitting element.
  • This light emitting element is applied to a GaAs or GaP light emitting element having a flip chip structure. Also, the light emitting element of this embodiment can reduce the loss produced in the alloy layer between the transparent substrate and the electrode, because the light reflecting layer is formed in a portion of the back side of the transparent substrate. As a consequence, in a region where the light reflecting layer is present, light can be efficiently reflected and emitted to the outside of the chip. [0199]
  • The material of this light reflecting layer is, e.g., Au. This is so because Au has high reflectance to light having a wavelength of 620 nm, which is generated in the InGaAlP active layer. [0200]
  • Table 1 shows the values of reflectance R and thermal conductivity k of metal materials. [0201]
  • Assume that these metal materials are in contact with the GaP substrate, and that the reflectance is a numerical value with respect to light having a wavelength of 620 nm. Refractive index n of GaP at this wavelength is 3.325. Assume also that the thermal conductivity is a numerical value at a temperature of 300 K. [0202]
    TABLE 1
    METAL REFLECTANCE R THERMAL CONDUCTIVITY k
    MATERIAL [%] [W/m · K]
    Al 77.6 237
    Cr 29.1 90.3
    Co 37.4 99.2
    Cu 87.7 398
    Au 92.1 315
    Hf 13 23
    Mo 20.4 138
    Ni 37.5 90.5
    Nb 18 53.7
    Os 5.3 87.3
    Ag 88.2 427
    Ta 20.3 57.5
    Ti 25.8 21.9
    W 15 178
  • The characteristics required for a light reflecting layer are high reflectance and high thermal conductivity. In a light emitting element using InGaAlP, a lowering of the emission efficiency by heat is significant. Therefore, efficiently radiating heat generated near the active layer to the outside of the element is important. For this purpose, as is apparent from Table [0203] 1, a material having high reflectance and high thermal conductivity, e.g., Au, Ag, Cu, or Al, is used as a light reflecting layer of a light emitting element.
  • Referring to FIG. 21, the area of the p-[0204] side electrode 68 and the area of the light reflecting layer 69 have the following relationship. That is, when the area of the p-side electrode 68 is made larger than that of the light reflecting layer 69, the contact resistance decreases, but the light reflection efficiency lowers; when the area of the light reflecting layer 69 is made larger than that of the p-side electrode 68, the light reflection efficiency rises, but the contact resistance increases.
  • In the light emitting element of this embodiment, the area ratio of the p-[0205] side electrode 68 to the light reflecting layer 69 is set at, e.g., 1:1. However, this ratio can be appropriately changed in accordance with the specification of a light emitting element. For example, in a light emitting element in which a rise of the contact resistance is of no problem, the area of the light reflecting layer 69 is made larger than that of the p-side electrode 68 to raise the light reflection efficiency.
  • FIG. 26 shows a modification of the light emitting element shown in FIG. 21. [0206]
  • The light emitting element of this modification is characterized in that the structure of a light reflecting layer is different from that of the light emitting element shown in FIG. 21. [0207]
  • A [0208] light reflecting layer 69 on the back side of a p-GaP substrate 60 is composed of an Si layer 72 and an Al2O3 layer 73. The thicknesses of the Si layer 72 and the A1 2O3 layer are so set as to be λ/4n (n indicates the refractive indices of Si and Al2O3 with respect to the wavelength of light generated in the active layer) with respect to a wavelength λ of light generated in the active layer.
  • The [0209] Si layer 72 and the Al2O3 73 have a large refractive index difference, and the absorption coefficient of the Si layer 72 having a high refractive index is small. Therefore, the light reflecting layer 69 can achieve high reflectance. However, the Al2O3 layer 68 having a low refractive index has small thermal conductivity and hence deteriorates the thermal characteristics of the element.
  • FIG. 27 shows the relationship between the electric current and the optical output of the light emitting element shown in FIG. 21. [0210]
  • Referring to FIG. 27, line {circle over ([0211] 1)} corresponds to the light emitting element shown in FIG. 21; line {circle over (2)}, the light emitting element shown in FIG. 26; and line {circle over (3)}, a conventional light emitting element.
  • According to this relationship, the light emitting element shown in FIG. 21 is most superior in optical output and durability. The optical output of the light emitting element shown in FIG. 26 saturates when the injection current increases under the influence of low thermal conductivity of Al[0212] 2O3. However, when the injection current is 150 mA or less, the optical output of this light emitting element shown in FIG. 26 is higher than that of the conventional light emitting element.
  • When the driving current is 20 mA, the characteristic of the light emitting element shown in FIG. 26 is substantially the same as that of the light emitting element shown in FIG. 21. Accordingly, it is well significant to use the light emitting element of this modification as an LED. [0213]
  • FIG. 28 shows the fifth embodiment of the light emitting element of the present invention. [0214]
  • This embodiment relates to a light emitting element which generates 620-nm red light in a GaAs light emitting element and a GaP light emitting element. [0215]
  • A [0216] light emitting layer 81 is formed on a portion of an n-GaP substrate 80. This light emitting layer 81 includes an n-InGaAlP contact layer 82, an n-InAlP cladding layer 83, an InGaAlP active layer 84, a p-InAlP cladding layer 85, and a p-InGaAlP contact layer 86.
  • An undoped GaP current limiting [0217] layer 87 is formed on the other portion (a region where the light emitting layer 81 is not formed) of the n-GaP substrate 80. A p-GaP layer 88 is formed on the light emitting layer 81 and the undoped GaP current limiting layer 87. A p-side electrode 89 is formed on the p-GaP layer 88. An n-side electrode 90 and a light reflecting layer 91 are formed on the back side of the n-GaP substrate 80.
  • Note that the n-[0218] side electrode 90 is positioned immediately below the light emitting layer 81.
  • A method of manufacturing the light emitting element shown in FIG. 28 will be described below. [0219]
  • First, as shown in FIG. 29, MO-CVD is used to form an n-In[0220] 0.5Ga0.15Al0.35 P contact layer 82, an n-In0.5Al0.5 P cladding layer 83, an In0.5Ga0.1Al0.4P active layer 84, a p-In0.5Al0.5 P cladding layer 85, and a p-In0.5Ga0.15Al0.35 P contact layer 86 in this order on an n-GaAs substrate 92. Subsequently, MO-CVD is used to form an undoped GaAs protective layer 93 and an SiO2 mask layer 94 in this order on the p-In0.5Ga0.15Al0.35 P contact layer 86.
  • Next, as shown in FIG. 30, the SiO[0221] 2 mask layer 94 is patterned by photolithography and wet etching. This SiO2 mask layer 94 is used as a mask to etch the GaAs protective layer 93, the p-In0.5Ga0.15Al0.35 P contact layer 86, the p-In0.5Al0.5 P cladding layer 85, the In0.5Ga0.1Al0.4P active layer 84, the n-In0.5Al0.5 P cladding layer 83, and the n-In0.5Ga0.15Al0.35 P contact layer 82 by RIE, thereby forming a ridge-shaped light emitting layer 81.
  • As shown in FIG. 31, an undoped GaP current limiting [0222] layer 87 is formed on the n-GaAs substrate 92 by CVD.
  • As shown in FIG. 32, a p-[0223] GaP layer 88 is formed on the light emitting layer 81 and the undoped GaP current limiting layer 87 by CVD. After that, the n-GaAs substrate 92 is entirely etched away to form a device as shown in FIG. 33.
  • As shown in FIG. 34, an n-[0224] GaP substrate 80 is bonded to the device shown in FIG. 33.
  • After that, as shown in FIG. 28, a p-[0225] side electrode 89 is formed on the p-GaP layer 88, and an n-side electrode 90 and a light reflecting layer 91 are formed on the back side of the n-GaP substrate 80.
  • Note that the [0226] light emitting layer 81 is positioned in a central portion of the n-GaP substrate 80 (or the chip) and surrounded by the undoped GaP current limiting layer 87.
  • Of red light generated in the InGaAlP [0227] active layer 84 of this light emitting element, light traveling to the p-side electrode is emitted to the outside of the chip through the p-InAlP cladding layer 85, the p-InGaAlP contact layer 86, and the p-GaP layer 88. Of the red light generated in the InGaAlP active layer 84, light heading to the n-GaP substrate 80 is reflected by the light reflecting layer 91 through the n-GaP substrate 80 which is a transparent substrate. This reflected light travels to the p-side electrode and is emitted to the outside of the chip.
  • In this structure, the n-[0228] side electrode 90 is positioned immediately below the InGaAlP active layer 83, and the light reflecting layer 91 is positioned immediately below the GaP current limiting layer 87. That is, light heading to the n-GaP substrate 80 is reflected by the light reflecting layer 91. Consequently, the reflected light is emitted to the outside of the chip through the GaP current limiting layer 87 whose bandgap energy is larger than its emission energy, without passing through the light emitting layer 81.
  • Since the reflected light does not pass through the [0229] light emitting layer 81, this reflected light is not again absorbed by the light emitting layer 81. Accordingly, the light emitting element of this embodiment can achieve sufficiently high light extraction efficiency. For example, when the light emitting element mounted in a package having an emission angle of 10° is operated with a driving current of 20 mA, the optical output is 1.4 times (about 20 cd) that of a conventional light emitting element.
  • In each of the first, second, and third embodiments of the light emitting element of the present invention, light generated in the active layer and traveling to the p-side electrode is reflected by the internal high-reflection layer of the p-side electrode, so the entire light is extracted to the outside of the chip from the back side of the substrate. In this arrangement, the electrode structure of the p-side electrode includes at least an ohmic layer for an ohmic contact, a barrier layer for preventing diffusion of metal impurities, and a high-reflection layer for reflecting light generated in the active layer with high reflectance. [0230]
  • The barrier layer is made of a high-melting material and prevents interdiffusion of metal atoms caused by heat between the ohmic layer and the high-reflection layer. Also, since the thicknesses of the ohmic layer and barrier layer are made as small as possible, the light absorption loss in these ohmic layer and barrier layer can be minimized. Therefore, in this p-side electrode it is possible to realize an ohmic contact and high light reflectance at the same time and suppress a rise of the operating voltage by heat. [0231]
  • As a consequence, the light emitting element and the semiconductor device using the same according to the present invention can realize high reliability and high performance. When the ohmic layer is made up of a plurality of dots (islands) arranged into arrays, it is possible to realize not only an ohmic contact but also high light extraction efficiency by high reflectance in a region where no ohmic layer exists, because absorption and loss of light can be reduced by the amount of ohmic layer. [0232]
  • In each of the fourth and fifth embodiments of the light emitting element of the present invention, light generated in the active layer and traveling to the substrate is reflected by the light reflecting layer, so the entire light is extracted to the outside of the chip from the surface of the p-GaP layer on the p-side electrode side. [0233]
  • Also, the electrode and the light reflecting layer are alternately arranged on the back side of the substrate. In a region where the electrode is present, scattering and absorption of light occur; in a region where the light reflecting layer is present, light is reflected with high efficiency. Accordingly, the light emitting element of the present invention can increase the light extraction efficiency and improve the performance of both the element and the semiconductor device using the element, compared to conventional light emitting elements. [0234]
  • Furthermore, the light emitting layer is formed in the shape of a ridge and surrounded by a transparent material (undoped GaP). In this structure, an electrode is placed immediately below the light emitting layer, and a light reflecting layer is placed immediately below the transparent material. Consequently, it is possible to prevent an event in which light reflected by the light reflecting layer is again absorbed in the light emitting layer, and to increase the light extraction efficiency. [0235]
  • As has been explained above, the electrode structure of the present invention can realize an ohmic contact and high light reflectance at the same time, and can also prevent interdiffusion of metal atoms between a plurality of layers forming the electrode. This makes it possible to increase the external quantum efficiency of a light emitting element, lower the operating voltage, and improve the reliability. [0236]
  • Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [0237]

Claims (60)

What is claimed is:
1. A light emitting element comprising:
a substrate;
a light emitting layer formed on said substrate to emit light; and
a first electrode contacting said light emitting layer,
wherein said first electrode comprises:
an ohmic layer in ohmic contact with said light emitting layer;
a first barrier layer formed on said ohmic layer to prevent diffusion of metal atoms; and
a light reflecting layer formed on said first barrier layer to reflect the light.
2. The light emitting element according to claim 1, wherein said substrate is an insulating substrate.
3. The light emitting element according to claim 1, wherein said substrate is a semiconductor substrate.
4. The light emitting element according to claim 3, further comprising a second electrode contacting said semiconductor substrate.
5. The light emitting element according to claim 1, wherein said light emitting layer comprises a light emitting diode.
6. The light emitting element according to claim 1, wherein said light emitting layer comprises:
a first semiconductor layer of first conductivity type;
an active layer formed on said first semiconductor layer to emit the light; and
a second semiconductor layer of second conductivity type formed on said active layer.
7. The light emitting element according to claim 6, wherein said first electrode contacts said second semiconductor layer.
8. The light emitting element according to claim 6, further comprising a second electrode contacting said first semiconductor layer.
9. The light emitting element according to claim 1, wherein the light is radiated from the back side of said substrate.
10. The light emitting element according to claim 1, wherein the light reflected by said light reflecting layer travels to the back side of said substrate.
11. The light emitting element according to claim 1, wherein said first barrier layer prevents diffusion of the metal atoms between said ohmic layer and said light reflecting layer.
12. The light emitting element according to claim 1, wherein said first barrier layer is made of a high-melting metal.
13. The light emitting element according to claim 1, wherein the thickness of said first barrier layer is not more than 10 nm.
14. The light emitting element according to claim 1, wherein said ohmic layer is a member of the group consisting of a metal, selected from the group consisting of Ni, Pt, Mg, Zn, Be, Ag, Au, and Ge, and an alloy containing the metal.
15. The light emitting element according to claim 1, wherein said first barrier layer is a member of the group consisting of a metal, selected from the group consisting of W, Mo, Pt, Ni, Ti, Pd, and V, and an alloy containing the metal.
16. The light emitting element according to claim 1, wherein said light reflecting layer is a member of the group consisting of a metal, selected from the group consisting of Al and Ag, and an alloy containing the metal.
17. The light emitting element according to claim 1, wherein said ohmic layer and said first barrier layer are made of the same material.
18. The light emitting element according to claim 17, wherein the material of said ohmic layer and said first barrier layer is a member of the group consisting of a metal, selected from the group consisting of Ni and Pt, and an alloy containing the metal.
19. The light emitting element according to claim 1, wherein said ohmic layer is made up of a plurality of islands arranged into arrays.
20. The light emitting element according to claim 19, wherein
a portion of the light passes through said ohmic layer and said first barrier layer and is reflected by said light reflecting layer, and
another portion of the light passes only through said first barrier layer and is reflected by said light reflecting layer.
21. The light emitting element according to claim 1, wherein said first electrode further comprises:
a second barrier layer formed on said light reflecting layer; and
an overcoat electrode for mounting formed on said second barrier layer.
22. The light emitting element according to claim 21, wherein said second barrier layer is made of a high-melting metal.
23. The light emitting element according to claim 1, wherein said first electrode is positioned in a central portion of said light emitting layer.
24. The light emitting element according to claim 8, wherein said first electrode is positioned in a central portion of said light emitting layer, and said second electrode surrounds said first electrode.
25. The light emitting element according to claim 4, wherein said second electrode is positioned on the edge of said semiconductor substrate.
26. The light emitting element according to claim 4, wherein said second electrode comprises a plurality of portions, and said plurality of portions are arranged apart form each other on the back side of said semiconductor substrate.
27. A light emitting element comprising:
a substrate;
a first semiconductor layer of first conductivity type formed on said substrate;
an active layer formed on said first semiconductor layer to emit light;
a second semiconductor layer of second conductivity type formed on said active layer;
a first electrode formed in a central portion of said second semiconductor layer and contacting said second semiconductor layer; and
a second electrode formed on the edge of said first semiconductor layer and contacting said first semiconductor layer.
28. A light emitting element comprising:
a substrate;
a first semiconductor layer of first conductivity type formed on said substrate;
an active layer formed on said first semiconductor layer to emit light;
a second semiconductor layer of second conductivity type formed on said active layer;
a first electrode formed in a central portion of said second semiconductor layer and contacting said second semiconductor layer; and
a second electrode contacting said first semiconductor layer and surrounding said first electrode.
29. A light emitting element comprising:
a transparent substrate;
a first semiconductor layer of first conductivity type formed on said transparent substrate;
an active layer formed on said first semiconductor layer to emit light;
a second semiconductor layer of second conductivity type formed on said active layer;
a first electrode contacting said second semiconductor layer;
a plurality of second electrodes contacting said transparent substrate; and
a plurality of light reflecting layers arranged between said plurality of second electrodes and contacting said transparent substrate.
30. A light emitting element comprising:
a transparent substrate;
a first semiconductor layer of first conductivity type formed on said transparent substrate;
an active layer formed on said first semiconductor layer to emit light;
a second semiconductor layer of second conductivity type formed on said active layer;
a first electrode contacting said second semiconductor layer;
a second electrode contacting said transparent substrate; and
a light reflecting layer contacting said transparent substrate.
31. The light emitting element according to claim 30, wherein said first semiconductor layer, said active layer, and said second semiconductor layer form a ridge-shaped member in a central portion of said transparent substrate.
32. The light emitting element according to claim 31, further comprising:
a current limiting layer formed on said transparent substrate to cover side surfaces of said ridge-shaped member; and
a third semiconductor layer formed on said ridge-shaped member and said current limiting layer.
33. The light emitting element according to claim 32, wherein said second electrode is positioned immediately below said ridge-shaped member.
34. The light emitting element according to claim 33, wherein said light reflecting layer surrounds said second electrode.
35. The light emitting element according to claim 30, wherein said light reflecting layer is made of a material selected from the group consisting of a metal and a material containing a metal.
36. The light emitting element according to claim 30, wherein said light reflecting layer is made of a material selected from the group consisting of a dielectric substance and a material containing a dielectric substance.
37. The light emitting element according to claim 30, wherein said light reflecting layer comprises a high-refractive-index layer whose refractive index to the light is higher than that of said transparent substrate, and a low-refractive-index layer whose refractive index to the light is lower than that of said high-refractive-index layer.
38. The light emitting element according to claim 30, wherein said first semiconductor layer, said active layer, and said second semiconductor layer are members of the group consisting of a compound, selected from the group consisting of InP, GaP, AlP, and GaAs, and a mixed crystal containing the compound.
39. A semiconductor device comprising:
a lead frame;
a submount on said lead frame;
a light emitting element on said submount; and
a resin covering said light emitting element,
wherein said light emitting element comprises:
a substrate;
a first semiconductor layer of first conductivity type formed on said substrate;
an active layer formed on said first semiconductor layer to emit light;
a second semiconductor layer of second conductivity type formed on said active layer;
a first electrode formed in a central portion of said second semiconductor layer and contacting said second semiconductor layer; and
a second electrode contacting said first semiconductor layer and surrounding said first electrode, and
said first electrode comprises:
an ohmic layer in ohmic contact with said second semiconductor layer;
a first barrier layer formed on said ohmic layer to prevent diffusion of metal atoms; and
a light reflecting layer formed on said first barrier layer to reflect the light.
40. A semiconductor device comprising:
a lead frame;
a submount on said lead frame;
a light emitting element on said submount; and
a resin covering said light emitting element,
wherein said light emitting element comprises:
a transparent substrate;
a first semiconductor layer of first conductivity type formed on said transparent substrate;
an active layer formed on said first semiconductor layer to emit light;
a second semiconductor layer of second conductivity type formed on said active layer;
a first electrode contacting said second semiconductor layer;
a second electrode contacting said transparent substrate; and
a light reflecting layer contacting said transparent substrate.
41. A manufacturing method of a light emitting element, comprising the steps of:
forming a first semiconductor layer of first conductivity type on a substrate;
forming an active layer on the first semiconductor layer;
forming a second semiconductor layer of second conductivity type on the active layer; and
forming a first electrode contacting the second semiconductor layer,
wherein the step of forming the first electrode comprises the steps of:
forming an ohmic layer on the second semiconductor layer;
forming an ohmic contact between the second semiconductor layer and the ohmic layer by first annealing;
forming a first barrier layer on the ohmic layer; and
forming, on the first barrier layer, a light reflecting layer having high reflectance to light generated in the active layer.
42. The manufacturing method according to claim 41, further comprising the steps of:
forming a second barrier layer on the light reflecting layer;
forming an overcoat electrode for mounting on the second barrier layer; and
performing second annealing at a temperature lower than that of the first annealing.
43. The manufacturing method according to claim 41, wherein said substrate is an insulating substrate.
44. The manufacturing method according to claim 41, wherein said substrate is a semiconductor substrate.
45. The manufacturing method according to claim 44, further comprising the step of forming a second electrode contacting the semiconductor substrate.
46. The manufacturing method according to claim 41, further comprising a second electrode contacting the first semiconductor layer.
47. The manufacturing method according to claim 41, wherein the first barrier layer prevents diffusion of metal atoms between the ohmic layer and the light reflecting layer.
48. The manufacturing method according to claim 41, wherein the first barrier layer is made of a high-melting metal.
49. The manufacturing method according to claim 41, wherein the thickness of the first barrier layer is not more than 10 nm.
50. The manufacturing method according to claim 41, wherein the ohmic layer is a member of the group consisting of a metal, selected from the group consisting of Ni, Pt, Mg, Zn, Be, Ag, Au, and Ge, and an alloy containing the metal.
51. The manufacturing method according to claim 41, wherein the first barrier layer is a member of the group consisting of a metal, selected from the group consisting of W, Mo, Pt, Ni, Ti, Pd, and V, and an alloy containing the metal.
52. The manufacturing method according to claim 41, wherein the light reflecting layer is a member of the group consisting of a metal, selected from the group consisting of Al and Ag, and an alloy containing the metal.
53. The manufacturing method according to claim 41, wherein the ohmic layer and the first barrier layer are made of the same material.
54. The manufacturing method according to claim 53, wherein the material of the ohmic layer and the first barrier layer is a member of the group consisting of a metal, selected from the group consisting of Ni and Pt, and an alloy containing the metal.
55. The manufacturing method according to claim 41, wherein the ohmic layer is made up of a plurality of islands arranged into arrays.
56. The manufacturing method according to claim 42, wherein the second barrier layer is made of a high-melting metal.
57. The manufacturing method according to claim 41, wherein the first electrode is positioned in a central portion of the second semiconductor layer.
58. The manufacturing method according to claim 46, wherein the first electrode is positioned in a central portion of the second semiconductor layer, and the second electrode surrounds the first electrode.
59. The manufacturing method according to claim 45, wherein the second electrode is positioned on the edge of the semiconductor substrate.
60. The manufacturing method according to claim 45, wherein the second electrode comprises a plurality of portions, which are arranged apart from each other on the back side of the semiconductor substrate.
US09/893,925 2000-06-30 2001-06-27 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element Abandoned US20020014630A1 (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US10/417,873 US6825502B2 (en) 2000-06-30 2003-04-17 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/945,707 US7179671B2 (en) 2000-06-30 2004-09-21 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/947,631 US7135714B2 (en) 2000-06-30 2004-09-22 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/946,787 US7138665B2 (en) 2000-06-30 2004-09-22 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/946,668 US7138664B2 (en) 2000-06-30 2004-09-22 Semiconductor device having a light emitting element
US10/958,910 US20050056857A1 (en) 2000-06-30 2004-10-04 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/958,911 US7221002B2 (en) 2000-06-30 2004-10-04 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2000200298A JP4024994B2 (en) 2000-06-30 2000-06-30 Semiconductor light emitting device
JP2000-200298 2000-06-30

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US10/417,873 Continuation US6825502B2 (en) 2000-06-30 2003-04-17 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element

Publications (1)

Publication Number Publication Date
US20020014630A1 true US20020014630A1 (en) 2002-02-07

Family

ID=18698187

Family Applications (9)

Application Number Title Priority Date Filing Date
US09/893,925 Abandoned US20020014630A1 (en) 2000-06-30 2001-06-27 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/417,873 Expired - Lifetime US6825502B2 (en) 2000-06-30 2003-04-17 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/945,707 Expired - Lifetime US7179671B2 (en) 2000-06-30 2004-09-21 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/946,787 Expired - Lifetime US7138665B2 (en) 2000-06-30 2004-09-22 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/946,668 Expired - Lifetime US7138664B2 (en) 2000-06-30 2004-09-22 Semiconductor device having a light emitting element
US10/947,631 Expired - Lifetime US7135714B2 (en) 2000-06-30 2004-09-22 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/958,910 Abandoned US20050056857A1 (en) 2000-06-30 2004-10-04 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/958,911 Expired - Lifetime US7221002B2 (en) 2000-06-30 2004-10-04 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US11/121,453 Expired - Fee Related US7355212B2 (en) 2000-06-30 2005-05-04 Light emitting element

Family Applications After (8)

Application Number Title Priority Date Filing Date
US10/417,873 Expired - Lifetime US6825502B2 (en) 2000-06-30 2003-04-17 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/945,707 Expired - Lifetime US7179671B2 (en) 2000-06-30 2004-09-21 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/946,787 Expired - Lifetime US7138665B2 (en) 2000-06-30 2004-09-22 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/946,668 Expired - Lifetime US7138664B2 (en) 2000-06-30 2004-09-22 Semiconductor device having a light emitting element
US10/947,631 Expired - Lifetime US7135714B2 (en) 2000-06-30 2004-09-22 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/958,910 Abandoned US20050056857A1 (en) 2000-06-30 2004-10-04 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US10/958,911 Expired - Lifetime US7221002B2 (en) 2000-06-30 2004-10-04 Light emitting element, method of manufacturing the same, and semiconductor device having light emitting element
US11/121,453 Expired - Fee Related US7355212B2 (en) 2000-06-30 2005-05-04 Light emitting element

Country Status (6)

Country Link
US (9) US20020014630A1 (en)
EP (1) EP1168460A3 (en)
JP (1) JP4024994B2 (en)
KR (2) KR100469312B1 (en)
CN (3) CN100587985C (en)
TW (1) TW531902B (en)

Cited By (37)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050045907A1 (en) * 2003-08-25 2005-03-03 Samsung Electronics Co., Ltd. Nitride-based light emitting device, and method of manufacturing the same
US20050145875A1 (en) * 2003-12-24 2005-07-07 Kim Hyun K. Flip chip type nitride semiconductor light emitting device and manufacturing method thereof
US20050151149A1 (en) * 2004-01-08 2005-07-14 Chia Chee W. Light emission device
US6969874B1 (en) * 2003-06-12 2005-11-29 Sandia Corporation Flip-chip light emitting diode with resonant optical microcavity
US20060081867A1 (en) * 2004-10-07 2006-04-20 Samsung Electronics Co., Ltd. Reflective electrode and compound semiconductor light emitting device including the same
US20060102933A1 (en) * 2004-11-04 2006-05-18 Kensaku Yamamoto III-V Group compound semiconductor light emitting device and manufacturing method thereof
US20060113548A1 (en) * 2004-11-29 2006-06-01 Ching-Chung Chen Light emitting diode
US20060157859A1 (en) * 2005-01-19 2006-07-20 Chih-Chen Chou Led packaging method and package structure
US20060228820A1 (en) * 2003-09-02 2006-10-12 Sebastien Kerdiles Multifunctional metallic bonding
US20070029568A1 (en) * 2002-11-16 2007-02-08 Sung Ho Choo Light emitting device and fabrication method thereof
US20070117235A1 (en) * 2003-02-26 2007-05-24 Osram Opto Semiconductors Gmbh Method for producing an electrical contact for an optoelectronic semiconductor chip
US20080230904A1 (en) * 2004-01-15 2008-09-25 Seoul Opto-Device Co., Ltd. Gallium Nitride-Based III-V Group Compound Semiconductor Device and Method of Manufacturing the Same
US20080230792A1 (en) * 2005-10-27 2008-09-25 Lattice Power (Jiangxi) Corporation Semiconductor Light-Emitting Device with Electrode for N-Polar Ingaain Surface
US20090184329A1 (en) * 2004-07-29 2009-07-23 Showa Denko K.K. Positive electrode for semiconductor light-emitting device
US20090189167A1 (en) * 2008-01-30 2009-07-30 Foxsemicon Integrated Technology, Inc. Light emitting device with high light extraction efficiency
US20090250716A1 (en) * 2004-07-27 2009-10-08 Kevin Haberern Light emitting devices having roughened/reflective contacts and methods of fabricating same
US20090290355A1 (en) * 2008-05-20 2009-11-26 Tae-Geun Kim Light-emitting device including reflective layer formed with curved surface and manufacturing method thereof
US20110037088A1 (en) * 2009-04-03 2011-02-17 Mitsuaki Oya Nitride-based semiconductor device and method for fabricating the same
US20110037089A1 (en) * 2009-04-03 2011-02-17 Mitsuaki Oya Nitride-based semiconductor device and method for fabricating the same
US7892874B2 (en) 2004-02-06 2011-02-22 Sanyo Electric Co., Ltd. Nitride-based light-emitting device and method of manufacturing the same
US8124986B2 (en) 2010-01-18 2012-02-28 Panasonic Corporation Nitride-based semiconductor device and method for fabricating the same
US20120199863A1 (en) * 2009-06-25 2012-08-09 Koninklijke Philips Electronics N.V. Contact for a semiconductor light emitting device
US8895419B2 (en) 2011-07-06 2014-11-25 Panasonic Corporation Nitride semiconductor light-emitting element and method for fabricating the same
US8933543B2 (en) 2010-04-02 2015-01-13 Panasonic Intellectual Property Management Co., Ltd. Nitride semiconductor element having m-plane angled semiconductor region and electrode including Mg and Ag
US20150280052A1 (en) * 2014-03-28 2015-10-01 Nichia Corporation Method for manufacturing light emitting device
US20160072004A1 (en) * 2014-09-05 2016-03-10 Samsung Electronics Co., Ltd. Semiconductor light emitting device
US9306124B2 (en) 2012-05-17 2016-04-05 Epistar Corporation Light emitting device with reflective electrode
US10411177B2 (en) 2008-08-18 2019-09-10 Epistar Corporation Light emitting device
US10847682B2 (en) 2012-11-02 2020-11-24 Epistar Corporation Electrode structure of light emitting device
US11284491B2 (en) 2011-12-02 2022-03-22 Lynk Labs, Inc. Color temperature controlled and low THD LED lighting devices and systems and methods of driving the same
US11297705B2 (en) 2007-10-06 2022-04-05 Lynk Labs, Inc. Multi-voltage and multi-brightness LED lighting devices and methods of using same
US11317495B2 (en) 2007-10-06 2022-04-26 Lynk Labs, Inc. LED circuits and assemblies
US11528792B2 (en) 2004-02-25 2022-12-13 Lynk Labs, Inc. High frequency multi-voltage and multi-brightness LED lighting devices
US11566759B2 (en) 2017-08-31 2023-01-31 Lynk Labs, Inc. LED lighting system and installation methods
US11638336B2 (en) 2004-02-25 2023-04-25 Lynk Labs, Inc. AC light emitting diode and AC LED drive methods and apparatus
US11678420B2 (en) 2004-02-25 2023-06-13 Lynk Labs, Inc. LED lighting system
US11749784B2 (en) 2018-10-23 2023-09-05 Seoul Viosys Co., Ltd. Flip chip type light emitting device

Families Citing this family (161)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4024994B2 (en) * 2000-06-30 2007-12-19 株式会社東芝 Semiconductor light emitting device
US6791119B2 (en) 2001-02-01 2004-09-14 Cree, Inc. Light emitting diodes including modifications for light extraction
US6794684B2 (en) * 2001-02-01 2004-09-21 Cree, Inc. Reflective ohmic contacts for silicon carbide including a layer consisting essentially of nickel, methods of fabricating same, and light emitting devices including the same
JP5283293B2 (en) * 2001-02-21 2013-09-04 ソニー株式会社 Semiconductor light emitting device
US6740906B2 (en) * 2001-07-23 2004-05-25 Cree, Inc. Light emitting diodes including modifications for submount bonding
US7211833B2 (en) 2001-07-23 2007-05-01 Cree, Inc. Light emitting diodes including barrier layers/sublayers
US8294172B2 (en) 2002-04-09 2012-10-23 Lg Electronics Inc. Method of fabricating vertical devices using a metal support film
US20030189215A1 (en) 2002-04-09 2003-10-09 Jong-Lam Lee Method of fabricating vertical structure leds
WO2003107443A2 (en) * 2002-06-17 2003-12-24 Kopin Corporation Bonding pad for gallium nitride-based light-emitting device
DE10244200A1 (en) 2002-09-23 2004-04-08 Osram Opto Semiconductors Gmbh Radiation-emitting semiconductor component
JP4116387B2 (en) * 2002-09-30 2008-07-09 株式会社東芝 Semiconductor light emitting device
US6929966B2 (en) 2002-11-29 2005-08-16 Osram Opto Semiconductors Gmbh Method for producing a light-emitting semiconductor component
DE10307280B4 (en) * 2002-11-29 2005-09-01 Osram Opto Semiconductors Gmbh Method for producing a light-emitting semiconductor component
DE10350707B4 (en) * 2003-02-26 2014-02-13 Osram Opto Semiconductors Gmbh Electrical contact for optoelectronic semiconductor chip and method for its production
JP2004281432A (en) * 2003-03-12 2004-10-07 Nichia Chem Ind Ltd Nitride semiconductor element and its manufacturing method
US7141828B2 (en) 2003-03-19 2006-11-28 Gelcore, Llc Flip-chip light emitting diode with a thermally stable multiple layer reflective p-type contact
WO2004086522A1 (en) * 2003-03-24 2004-10-07 Showa Denko K.K. Ohmic electrode structure, compound semiconductor light-emitting device having the same, and led lamp
US7166871B2 (en) * 2003-04-15 2007-01-23 Luminus Devices, Inc. Light emitting systems
US7521854B2 (en) 2003-04-15 2009-04-21 Luminus Devices, Inc. Patterned light emitting devices and extraction efficiencies related to the same
US7262550B2 (en) 2003-04-15 2007-08-28 Luminus Devices, Inc. Light emitting diode utilizing a physical pattern
US6831302B2 (en) 2003-04-15 2004-12-14 Luminus Devices, Inc. Light emitting devices with improved extraction efficiency
US7667238B2 (en) 2003-04-15 2010-02-23 Luminus Devices, Inc. Light emitting devices for liquid crystal displays
US7084434B2 (en) 2003-04-15 2006-08-01 Luminus Devices, Inc. Uniform color phosphor-coated light-emitting diode
US7211831B2 (en) 2003-04-15 2007-05-01 Luminus Devices, Inc. Light emitting device with patterned surfaces
US7098589B2 (en) 2003-04-15 2006-08-29 Luminus Devices, Inc. Light emitting devices with high light collimation
US7105861B2 (en) * 2003-04-15 2006-09-12 Luminus Devices, Inc. Electronic device contact structures
US7074631B2 (en) * 2003-04-15 2006-07-11 Luminus Devices, Inc. Light emitting device methods
US7274043B2 (en) 2003-04-15 2007-09-25 Luminus Devices, Inc. Light emitting diode systems
US7083993B2 (en) * 2003-04-15 2006-08-01 Luminus Devices, Inc. Methods of making multi-layer light emitting devices
US20040259279A1 (en) 2003-04-15 2004-12-23 Erchak Alexei A. Light emitting device methods
KR100826424B1 (en) * 2003-04-21 2008-04-29 삼성전기주식회사 Semiconductor type light emitting diode and manufacturing method thereof
KR100612832B1 (en) * 2003-05-07 2006-08-18 삼성전자주식회사 Metal thin film and the produce method for development of ohmic contact using Ni-based solid solution for high-quality optical devices related to GaN
JP3951300B2 (en) * 2003-07-23 2007-08-01 信越半導体株式会社 Light emitting device and method for manufacturing light emitting device
TWI220076B (en) * 2003-08-27 2004-08-01 Au Optronics Corp Light-emitting device
KR100571816B1 (en) * 2003-09-08 2006-04-17 삼성전자주식회사 light emitting device and method of manufacturing the same
US7341880B2 (en) * 2003-09-17 2008-03-11 Luminus Devices, Inc. Light emitting device processes
US7344903B2 (en) 2003-09-17 2008-03-18 Luminus Devices, Inc. Light emitting device processes
KR100576849B1 (en) * 2003-09-19 2006-05-10 삼성전기주식회사 Light emitting device and method for manufacturing the same
JP4130163B2 (en) * 2003-09-29 2008-08-06 三洋電機株式会社 Semiconductor light emitting device
EP1521312A3 (en) * 2003-09-30 2008-01-16 Osram Opto Semiconductors GmbH Optoelectronic device having a metallised carrier
KR100571818B1 (en) * 2003-10-08 2006-04-17 삼성전자주식회사 light emitting device and method of manufacturing the same
KR100647278B1 (en) * 2003-10-27 2006-11-17 삼성전자주식회사 GaN-based III - V group compound semiconductor and p-typed electrode for the semiconductor
US7341882B2 (en) * 2003-11-18 2008-03-11 Uni Light Technology Inc. Method for forming an opto-electronic device
US7450311B2 (en) 2003-12-12 2008-11-11 Luminus Devices, Inc. Optical display systems and methods
US20050133806A1 (en) * 2003-12-17 2005-06-23 Hui Peng P and N contact pad layout designs of GaN based LEDs for flip chip packaging
KR100978234B1 (en) 2004-01-06 2010-08-26 삼성엘이디 주식회사 A low-resistance electrode of compound semiconductor light emitting device and a compound semiconductor light emitting device using the electrode
US7960746B2 (en) * 2004-01-06 2011-06-14 Samsung Led Co., Ltd. Low resistance electrode and compound semiconductor light emitting device including the same
KR100586949B1 (en) * 2004-01-19 2006-06-07 삼성전기주식회사 Flip chip type nitride semiconductor light emitting diode
JP2005228924A (en) * 2004-02-13 2005-08-25 Toshiba Corp Semiconductor light emitting element
JP2005277372A (en) * 2004-02-25 2005-10-06 Sanken Electric Co Ltd Semiconductor light emitting device and its manufacturing method
JP2005259820A (en) 2004-03-09 2005-09-22 Sharp Corp Group iii-v compound semiconductor light emitting element and its manufacturing method
KR100634503B1 (en) 2004-03-12 2006-10-16 삼성전자주식회사 Light emitting device and method of manufacturing thereof
KR20050095721A (en) * 2004-03-27 2005-09-30 삼성전자주식회사 Gan-based iii - v group compound semiconductor light emitting device and method of fabricating the same
JP2005317676A (en) 2004-04-27 2005-11-10 Sony Corp Semiconductor light emitting device, manufacturing method thereof and semiconductor light emitting apparatus
JP2005347632A (en) * 2004-06-04 2005-12-15 Sharp Corp Semiconductor device and electronic equipment
CN100463243C (en) * 2004-06-14 2009-02-18 北京大学 Push-out light electrode and its production
JP2006041498A (en) * 2004-06-24 2006-02-09 Showa Denko Kk Reflective positive electrode and gallium nitride compound semiconductor light emitting device using the same
KR100838215B1 (en) * 2004-06-24 2008-06-13 쇼와 덴코 가부시키가이샤 Reflective positive electrode and gallium nitride-based compound semiconductor light-emitting device using the same
TWI374552B (en) 2004-07-27 2012-10-11 Cree Inc Ultra-thin ohmic contacts for p-type nitride light emitting devices and methods of forming
US20060038188A1 (en) 2004-08-20 2006-02-23 Erchak Alexei A Light emitting diode systems
JP4807983B2 (en) * 2004-08-24 2011-11-02 昭和電工株式会社 Positive electrode for compound semiconductor light emitting device, light emitting device and lamp using the positive electrode
TWI257714B (en) * 2004-10-20 2006-07-01 Arima Optoelectronics Corp Light-emitting device using multilayer composite metal plated layer as flip-chip electrode
US7679097B2 (en) 2004-10-21 2010-03-16 Nichia Corporation Semiconductor light emitting device and method for manufacturing the same
CN100358167C (en) * 2004-12-17 2007-12-26 北京工业大学 GaN base LED high reflectance electrode
CN1330011C (en) * 2004-12-17 2007-08-01 北京工业大学 Low contact resistance low light absorption and full angle high reflectance LED electrode
CN100435360C (en) * 2004-12-27 2008-11-19 北京大学 Method for preparing LED chip with 2D natural scattered faces for outputting light
EP1681712A1 (en) * 2005-01-13 2006-07-19 S.O.I. Tec Silicon on Insulator Technologies S.A. Method of producing substrates for optoelectronic applications
US7045375B1 (en) * 2005-01-14 2006-05-16 Au Optronics Corporation White light emitting device and method of making same
US7170100B2 (en) 2005-01-21 2007-01-30 Luminus Devices, Inc. Packaging designs for LEDs
TWI247441B (en) * 2005-01-21 2006-01-11 United Epitaxy Co Ltd Light emitting diode and fabricating method thereof
US7692207B2 (en) * 2005-01-21 2010-04-06 Luminus Devices, Inc. Packaging designs for LEDs
CN100379042C (en) * 2005-02-18 2008-04-02 乐清市亿昊科技发展有限公司 Substrate structure for light-emitting diode tube core and method for making same
JP2006245379A (en) * 2005-03-04 2006-09-14 Stanley Electric Co Ltd Semiconductor light emitting device
US20070045640A1 (en) 2005-08-23 2007-03-01 Erchak Alexei A Light emitting devices for liquid crystal displays
US7411225B2 (en) * 2005-03-21 2008-08-12 Lg Electronics Inc. Light source apparatus
JP2006269912A (en) * 2005-03-25 2006-10-05 Matsushita Electric Ind Co Ltd Light emitting device and manufacturing method thereof
KR100631976B1 (en) * 2005-03-30 2006-10-11 삼성전기주식회사 Group iii-nitride light emitting device
EP1708283A1 (en) * 2005-04-02 2006-10-04 Lg Electronics Inc. Light source apparatus and fabrication method thereof
US7244630B2 (en) * 2005-04-05 2007-07-17 Philips Lumileds Lighting Company, Llc A1InGaP LED having reduced temperature dependence
KR100691264B1 (en) 2005-07-20 2007-03-12 삼성전기주식회사 Vertical structured nitride based semiconductor light emitting device
JP2007035990A (en) * 2005-07-28 2007-02-08 Kyocera Corp Gallium-nitride-based compound semiconductor light emitting element, and manufacturing method thereof
JP4963807B2 (en) * 2005-08-04 2012-06-27 昭和電工株式会社 Gallium nitride compound semiconductor light emitting device
SG130975A1 (en) * 2005-09-29 2007-04-26 Tinggi Tech Private Ltd Fabrication of semiconductor devices for light emission
KR100721147B1 (en) * 2005-11-23 2007-05-22 삼성전기주식회사 Vertically structured gan type led device
US8044412B2 (en) 2006-01-20 2011-10-25 Taiwan Semiconductor Manufacturing Company, Ltd Package for a light emitting element
JP2007201046A (en) * 2006-01-25 2007-08-09 Kyocera Corp Compound semiconductor and light emitting element
JP2007214276A (en) * 2006-02-08 2007-08-23 Mitsubishi Chemicals Corp Light-emitting element
US7622746B1 (en) * 2006-03-17 2009-11-24 Bridgelux, Inc. Highly reflective mounting arrangement for LEDs
KR101198763B1 (en) * 2006-03-23 2012-11-12 엘지이노텍 주식회사 Post structure and LED using the structure and method of making the same
US7423297B2 (en) * 2006-05-03 2008-09-09 3M Innovative Properties Company LED extractor composed of high index glass
US7501295B2 (en) * 2006-05-25 2009-03-10 Philips Lumileds Lighting Company, Llc Method of fabricating a reflective electrode for a semiconductor light emitting device
US7479466B2 (en) * 2006-07-14 2009-01-20 Taiwan Semiconductor Manufacturing Co., Ltd. Method of heating semiconductor wafer to improve wafer flatness
US7813400B2 (en) * 2006-11-15 2010-10-12 Cree, Inc. Group-III nitride based laser diode and method for fabricating same
US8045595B2 (en) * 2006-11-15 2011-10-25 Cree, Inc. Self aligned diode fabrication method and self aligned laser diode
KR100836494B1 (en) 2006-12-26 2008-06-09 엘지이노텍 주식회사 Semiconductor light emitting device
CN100403568C (en) * 2006-12-30 2008-07-16 武汉华灿光电有限公司 Electrode of gallium nitride base III-V. class compound semiconductor
US8110425B2 (en) 2007-03-20 2012-02-07 Luminus Devices, Inc. Laser liftoff structure and related methods
JP2008288248A (en) * 2007-05-15 2008-11-27 Hitachi Cable Ltd Semiconductor light-emitting element
KR100872717B1 (en) 2007-06-22 2008-12-05 엘지이노텍 주식회사 Light emitting device and manufacturing method thereof
US8441018B2 (en) 2007-08-16 2013-05-14 The Trustees Of Columbia University In The City Of New York Direct bandgap substrates and methods of making and using
JP5474292B2 (en) * 2007-11-06 2014-04-16 シャープ株式会社 Nitride semiconductor light emitting diode device
US9024327B2 (en) 2007-12-14 2015-05-05 Cree, Inc. Metallization structure for high power microelectronic devices
JP2008103759A (en) * 2007-12-26 2008-05-01 Matsushita Electric Ind Co Ltd Light emitting element
US7875534B2 (en) * 2008-07-21 2011-01-25 Taiwan Semiconductor Manufacturing Company, Ltd. Realizing N-face III-nitride semiconductors by nitridation treatment
US20100055479A1 (en) * 2008-08-29 2010-03-04 Caterpillar Inc. Coating for a combustion chamber defining component
CN102376841A (en) * 2008-12-22 2012-03-14 亿光电子工业股份有限公司 Light-emitting diode structure and manufacturing method thereof
CN101752475B (en) * 2008-12-22 2012-06-20 亿光电子工业股份有限公司 Luminous diode structure and manufacture method thereof
TWI384660B (en) * 2009-01-23 2013-02-01 Everlight Electronics Co Ltd Light emitting diode package structure and method thereof
CN102007611B (en) * 2009-04-02 2013-01-02 松下电器产业株式会社 Nitride semiconductor element and method for producing the same
KR101041068B1 (en) * 2009-06-29 2011-06-13 주식회사 프로텍 Method of manufacturing light emitting diode using submount substrate
US8076682B2 (en) * 2009-07-21 2011-12-13 Koninklijke Philips Electronics N.V. Contact for a semiconductor light emitting device
KR101072034B1 (en) 2009-10-15 2011-10-10 엘지이노텍 주식회사 Semiconductor light emitting device and fabrication method thereof
KR101014013B1 (en) 2009-10-15 2011-02-10 엘지이노텍 주식회사 Semiconductor light emitting device and fabrication method thereof
KR101081193B1 (en) 2009-10-15 2011-11-07 엘지이노텍 주식회사 Semiconductor light emitting device and fabrication method thereof
JP4803302B2 (en) * 2009-12-17 2011-10-26 三菱化学株式会社 Nitride semiconductor light emitting device
US8728843B2 (en) * 2010-02-26 2014-05-20 Nichia Corporation Nitride semiconductor light emitting element and method for manufacturing same
KR101039879B1 (en) * 2010-04-12 2011-06-09 엘지이노텍 주식회사 Light emitting device and fabrication method thereof
JP5693375B2 (en) 2010-05-28 2015-04-01 シチズンホールディングス株式会社 Semiconductor light emitting device
CN102315354B (en) * 2010-06-29 2013-11-06 展晶科技(深圳)有限公司 Packaging structure of light emitting diode
US9548286B2 (en) * 2010-08-09 2017-01-17 Micron Technology, Inc. Solid state lights with thermal control elements
KR101731056B1 (en) 2010-08-13 2017-04-27 서울바이오시스 주식회사 Semiconductor light emitting device having ohmic electrode structure and method of fabricating the same
DE102010045784B4 (en) 2010-09-17 2022-01-20 OSRAM Opto Semiconductors Gesellschaft mit beschränkter Haftung Optoelectronic semiconductor chip
JP5016712B2 (en) * 2010-09-21 2012-09-05 三井金属鉱業株式会社 Electrode foil and organic device
JP5592248B2 (en) * 2010-12-27 2014-09-17 シャープ株式会社 Nitride semiconductor light emitting device
JP4940363B1 (en) 2011-02-28 2012-05-30 株式会社東芝 Semiconductor light emitting device and semiconductor light emitting device
JP2012204373A (en) * 2011-03-23 2012-10-22 Toyoda Gosei Co Ltd Semiconductor light-emitting element
CN102738331A (en) * 2011-04-08 2012-10-17 新世纪光电股份有限公司 Vertical light-emitting diode structure and method for manufacturing the same
JP6077201B2 (en) * 2011-08-11 2017-02-08 昭和電工株式会社 Light emitting diode and manufacturing method thereof
CN102956791B (en) * 2011-08-18 2015-04-29 展晶科技(深圳)有限公司 LED package structure
EP2791983A4 (en) * 2011-12-12 2015-08-12 Sensor Electronic Tech Inc Ultraviolet reflective contact
US9818912B2 (en) 2011-12-12 2017-11-14 Sensor Electronic Technology, Inc. Ultraviolet reflective contact
JP5853672B2 (en) * 2011-12-22 2016-02-09 日亜化学工業株式会社 GaN-based semiconductor light emitting device
JP5639626B2 (en) 2012-01-13 2014-12-10 シャープ株式会社 Semiconductor light emitting device and electrode film forming method
GB201202222D0 (en) * 2012-02-09 2012-03-28 Mled Ltd Enhanced light extraction
US9209356B2 (en) * 2012-06-08 2015-12-08 Epistar Corporation Light-emitting element including a light-emitting stack with an uneven upper surface
US9269662B2 (en) * 2012-10-17 2016-02-23 Cree, Inc. Using stress reduction barrier sub-layers in a semiconductor die
CN102956777B (en) * 2012-10-26 2015-07-15 江苏威纳德照明科技有限公司 GaP (gallium phosphide)-based light emitting diode with interface texturing layer and manufacturing method of GaP-based light emitting diode with interface texturing layer
US9082935B2 (en) * 2012-11-05 2015-07-14 Epistar Corporation Light-emitting element and the light-emitting array having the same
US9536924B2 (en) 2012-12-06 2017-01-03 Seoul Viosys Co., Ltd. Light-emitting diode and application therefor
CN109979925B (en) 2012-12-06 2024-03-01 首尔伟傲世有限公司 Light emitting diode
KR20140086624A (en) * 2012-12-28 2014-07-08 삼성전자주식회사 Nitride-based semiconductor light-emitting device
US9768357B2 (en) 2013-01-09 2017-09-19 Sensor Electronic Technology, Inc. Ultraviolet reflective rough adhesive contact
US10276749B2 (en) 2013-01-09 2019-04-30 Sensor Electronic Technology, Inc. Ultraviolet reflective rough adhesive contact
US9287449B2 (en) 2013-01-09 2016-03-15 Sensor Electronic Technology, Inc. Ultraviolet reflective rough adhesive contact
KR20140116574A (en) * 2013-03-25 2014-10-06 인텔렉추얼디스커버리 주식회사 Light generating device and method of manufacturing the same
CN103178180A (en) * 2013-03-26 2013-06-26 合肥彩虹蓝光科技有限公司 Novel metal electrode gasket with low cost and high conductivity, and preparation method of gasket
JP6023660B2 (en) * 2013-05-30 2016-11-09 スタンレー電気株式会社 Semiconductor light emitting device and semiconductor light emitting device
CN103594597B (en) * 2013-10-22 2016-09-07 溧阳市东大技术转移中心有限公司 A kind of laminate electrode on luminescent device
TWI514628B (en) * 2013-10-24 2015-12-21 Lextar Electronics Corp Electrode structure and light emitting diode structure having the same
CN104681685A (en) * 2013-11-28 2015-06-03 亚世达科技股份有限公司 Light-emitting diode device and lamp
CN104103733B (en) * 2014-06-18 2018-06-05 华灿光电(苏州)有限公司 A kind of upside-down mounting LED chip and its manufacturing method
CN104409601A (en) * 2014-11-05 2015-03-11 扬州中科半导体照明有限公司 Flip light-emitting diode chip with double reflection layers
KR102373677B1 (en) 2015-08-24 2022-03-14 쑤저우 레킨 세미컨덕터 컴퍼니 리미티드 Light emittng device
JP2017054901A (en) * 2015-09-09 2017-03-16 豊田合成株式会社 Group iii nitride semiconductor light emitting device and manufacturing method of the same
DE102015116855A1 (en) * 2015-10-05 2017-04-06 Osram Opto Semiconductors Gmbh Optoelectronic component with a lead frame with a stiffening structure
US10043941B1 (en) * 2017-01-31 2018-08-07 International Business Machines Corporation Light emitting diode having improved quantum efficiency at low injection current
KR102051477B1 (en) * 2018-02-26 2019-12-04 주식회사 세미콘라이트 Method of manufacturing semiconductor light emitting device
CN111129251A (en) * 2019-12-30 2020-05-08 广东德力光电有限公司 Electrode structure of high-weldability flip LED chip
CN111653653B (en) * 2020-06-17 2021-10-22 京东方科技集团股份有限公司 Light-emitting device, manufacturing method thereof and display panel
CN112768582B (en) * 2021-02-26 2022-03-25 南京大学 Flip LED chip comprising high-reflection n-GaN ohmic contact and manufacturing method thereof
CN113571622B (en) * 2021-07-22 2022-08-23 厦门三安光电有限公司 Light emitting diode and method for manufacturing the same

Family Cites Families (56)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS49149679U (en) * 1973-04-27 1974-12-25
CA1139412A (en) * 1980-09-10 1983-01-11 Northern Telecom Limited Light emitting diodes with high external quantum efficiency
US4510514A (en) * 1983-08-08 1985-04-09 At&T Bell Laboratories Ohmic contacts for semiconductor devices
JPH0670981B2 (en) * 1986-07-08 1994-09-07 三洋電機株式会社 Electrode forming method
JPH0488684A (en) * 1990-08-01 1992-03-23 Koito Mfg Co Ltd Led chip electrode structure
JP2871288B2 (en) * 1992-04-10 1999-03-17 日本電気株式会社 Surface type optical semiconductor device and method of manufacturing the same
JPH0645651A (en) * 1992-05-22 1994-02-18 Sanyo Electric Co Ltd Electrode for n-type sic and its formation
JPH0669546A (en) * 1992-08-21 1994-03-11 Asahi Chem Ind Co Ltd Light-emitting diode
US5578162A (en) * 1993-06-25 1996-11-26 Lucent Technologies Inc. Integrated composite semiconductor devices and method for manufacture thereof
JPH0738146A (en) * 1993-07-20 1995-02-07 Victor Co Of Japan Ltd Semiconductor light emitting device
JP3627822B2 (en) * 1994-08-18 2005-03-09 ローム株式会社 Semiconductor light emitting device and manufacturing method thereof
US5557115A (en) * 1994-08-11 1996-09-17 Rohm Co. Ltd. Light emitting semiconductor device with sub-mount
JP3198016B2 (en) * 1994-08-25 2001-08-13 シャープ株式会社 Light emitting diode array and method of manufacturing the same
JP3057547B2 (en) 1995-04-12 2000-06-26 財団法人半導体研究振興会 Green light emitting diode
JP3065509B2 (en) * 1995-06-02 2000-07-17 スタンレー電気株式会社 Surface mount type light emitting diode
US5625202A (en) * 1995-06-08 1997-04-29 University Of Central Florida Modified wurtzite structure oxide compounds as substrates for III-V nitride compound semiconductor epitaxial thin film growth
WO1997001190A1 (en) * 1995-06-21 1997-01-09 Rohm Co., Ltd. Light-emitting diode chip and light-emitting diode using the same
JP3333356B2 (en) * 1995-07-12 2002-10-15 株式会社東芝 Semiconductor device
JP3269070B2 (en) * 1995-10-30 2002-03-25 日亜化学工業株式会社 Nitride semiconductor light emitting device
US5760423A (en) * 1996-11-08 1998-06-02 Kabushiki Kaisha Toshiba Semiconductor light emitting device, electrode of the same device and method of manufacturing the same device
US5917202A (en) * 1995-12-21 1999-06-29 Hewlett-Packard Company Highly reflective contacts for light emitting semiconductor devices
US5977566A (en) * 1996-06-05 1999-11-02 Kabushiki Kaisha Toshiba Compound semiconductor light emitter
FR2750804B1 (en) * 1996-07-04 1998-09-11 Alsthom Cge Alcatel METHOD FOR MANUFACTURING A SURFACE EMITTED LASER
JP3504079B2 (en) * 1996-08-31 2004-03-08 株式会社東芝 Method for manufacturing semiconductor light emitting diode device
US6268618B1 (en) * 1997-05-08 2001-07-31 Showa Denko K.K. Electrode for light-emitting semiconductor devices and method of producing the electrode
JPH118410A (en) 1997-06-18 1999-01-12 Nichia Chem Ind Ltd Electrode of n-type nitride semiconductor
KR100235994B1 (en) * 1997-07-10 1999-12-15 구자홍 A light emiting diode and a method of fabricating the same
JP3257455B2 (en) * 1997-07-17 2002-02-18 松下電器産業株式会社 Light emitting device
JP3130292B2 (en) * 1997-10-14 2001-01-31 松下電子工業株式会社 Semiconductor light emitting device and method of manufacturing the same
JP2001525186A (en) 1997-11-27 2001-12-11 マックス−プランク−ゲゼルシャフト ツール フォルデルング デル ヴィッセンシャフテン エー.ファウ. Identification and characterization of interacting molecules
DE69839300T2 (en) * 1997-12-15 2009-04-16 Philips Lumileds Lighting Company, LLC, San Jose Light-emitting device
JPH11186613A (en) * 1997-12-19 1999-07-09 Matsushita Electron Corp Semiconductor light emitting device
KR19990052640A (en) * 1997-12-23 1999-07-15 김효근 Metal thin film for diode using ohmic contact formation and manufacturing method thereof
JPH11220168A (en) * 1998-02-02 1999-08-10 Toyoda Gosei Co Ltd Gallium nitride compound semiconductor device and manufacture thereof
JPH11229168A (en) 1998-02-17 1999-08-24 Mitsubishi Heavy Ind Ltd Hydrogen peroxide generating device
JP3582349B2 (en) * 1998-03-04 2004-10-27 豊田合成株式会社 Gallium nitride based compound semiconductor device
JP4183299B2 (en) * 1998-03-25 2008-11-19 株式会社東芝 Gallium nitride compound semiconductor light emitting device
JPH11298040A (en) 1998-04-10 1999-10-29 Sharp Corp Semiconductor light-emitting element and manufacture thereof
JP3736181B2 (en) * 1998-05-13 2006-01-18 豊田合成株式会社 Group III nitride compound semiconductor light emitting device
DE19921987B4 (en) * 1998-05-13 2007-05-16 Toyoda Gosei Kk Light-emitting semiconductor device with group III element-nitride compounds
JP3785820B2 (en) * 1998-08-03 2006-06-14 豊田合成株式会社 Light emitting device
JP2000091638A (en) * 1998-09-14 2000-03-31 Matsushita Electric Ind Co Ltd Gallium nitride compound semiconductor light emitting element
JP2000156527A (en) * 1998-11-19 2000-06-06 Matsushita Electronics Industry Corp Semiconductor light emitting device
US6307218B1 (en) * 1998-11-20 2001-10-23 Lumileds Lighting, U.S., Llc Electrode structures for light emitting devices
JP3739951B2 (en) * 1998-11-25 2006-01-25 東芝電子エンジニアリング株式会社 Semiconductor light emitting device and manufacturing method thereof
US6222207B1 (en) * 1999-05-24 2001-04-24 Lumileds Lighting, U.S. Llc Diffusion barrier for increased mirror reflectivity in reflective solderable contacts on high power LED chip
US6133589A (en) * 1999-06-08 2000-10-17 Lumileds Lighting, U.S., Llc AlGaInN-based LED having thick epitaxial layer for improved light extraction
US6486499B1 (en) * 1999-12-22 2002-11-26 Lumileds Lighting U.S., Llc III-nitride light-emitting device with increased light generating capability
US6992334B1 (en) * 1999-12-22 2006-01-31 Lumileds Lighting U.S., Llc Multi-layer highly reflective ohmic contacts for semiconductor devices
JP2001217456A (en) * 2000-02-03 2001-08-10 Sharp Corp Gallium nitride system compound semiconductor light- emitting device
US6586328B1 (en) * 2000-06-05 2003-07-01 The Board Of Trustees Of The University Of Illinois Method to metallize ohmic electrodes to P-type group III nitrides
JP4024994B2 (en) * 2000-06-30 2007-12-19 株式会社東芝 Semiconductor light emitting device
US6445007B1 (en) * 2001-03-19 2002-09-03 Uni Light Technology Inc. Light emitting diodes with spreading and improving light emitting area
JP2002368275A (en) * 2001-06-11 2002-12-20 Toyoda Gosei Co Ltd Semiconductor device and manufacturing method therefor
JP4055503B2 (en) * 2001-07-24 2008-03-05 日亜化学工業株式会社 Semiconductor light emitting device
JP4148264B2 (en) * 2003-11-19 2008-09-10 日亜化学工業株式会社 Semiconductor device and manufacturing method thereof

Cited By (66)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20070029568A1 (en) * 2002-11-16 2007-02-08 Sung Ho Choo Light emitting device and fabrication method thereof
US20100237384A1 (en) * 2002-11-16 2010-09-23 Sung Ho Choo Light device and fabrication method thereof
US8969883B2 (en) * 2002-11-16 2015-03-03 Lg Innotek Co., Ltd. Semiconductor light device and fabrication method thereof
US8143643B2 (en) 2002-11-16 2012-03-27 Lg Innotek Co., Ltd. Light device and fabrication method thereof
US20070117235A1 (en) * 2003-02-26 2007-05-24 Osram Opto Semiconductors Gmbh Method for producing an electrical contact for an optoelectronic semiconductor chip
US7696078B2 (en) * 2003-02-26 2010-04-13 Osram Opto Semiconductors Gmbh Method for producing an electrical contact for an optoelectronic semiconductor chip
US6969874B1 (en) * 2003-06-12 2005-11-29 Sandia Corporation Flip-chip light emitting diode with resonant optical microcavity
US7462877B2 (en) * 2003-08-25 2008-12-09 Samsung Electronics Co., Ltd. Nitride-based light emitting device, and method of manufacturing the same
US20050045907A1 (en) * 2003-08-25 2005-03-03 Samsung Electronics Co., Ltd. Nitride-based light emitting device, and method of manufacturing the same
US20060228820A1 (en) * 2003-09-02 2006-10-12 Sebastien Kerdiles Multifunctional metallic bonding
US7189632B2 (en) 2003-09-02 2007-03-13 S.O.I.Tec Silicon On Insulator Technologies S.A. Multifunctional metallic bonding
US7232739B2 (en) 2003-09-02 2007-06-19 S.O.I. Tec Silicon On Insulator Technologies Multifunctional metallic bonding
US7235818B2 (en) 2003-12-24 2007-06-26 Samsung Electro-Mechanics Co., Ltd Flip chip type nitride semiconductor light emitting device and manufacturing method thereof
US20050145875A1 (en) * 2003-12-24 2005-07-07 Kim Hyun K. Flip chip type nitride semiconductor light emitting device and manufacturing method thereof
US7183588B2 (en) * 2004-01-08 2007-02-27 Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. Light emission device
US20050151149A1 (en) * 2004-01-08 2005-07-14 Chia Chee W. Light emission device
US20080230904A1 (en) * 2004-01-15 2008-09-25 Seoul Opto-Device Co., Ltd. Gallium Nitride-Based III-V Group Compound Semiconductor Device and Method of Manufacturing the Same
US8323999B2 (en) 2004-01-15 2012-12-04 Seoul Opto Device Co., Ltd. Gallium nitride-based III-V group compound semiconductor device and method of manufacturing the same
US7859109B2 (en) * 2004-01-15 2010-12-28 Seoul Opto-Device Co., Ltd. Gallium nitride-based III-V group compound semiconductor device and method of manufacturing the same
US7892874B2 (en) 2004-02-06 2011-02-22 Sanyo Electric Co., Ltd. Nitride-based light-emitting device and method of manufacturing the same
US11528792B2 (en) 2004-02-25 2022-12-13 Lynk Labs, Inc. High frequency multi-voltage and multi-brightness LED lighting devices
US11638336B2 (en) 2004-02-25 2023-04-25 Lynk Labs, Inc. AC light emitting diode and AC LED drive methods and apparatus
US11678420B2 (en) 2004-02-25 2023-06-13 Lynk Labs, Inc. LED lighting system
US8669563B2 (en) * 2004-07-27 2014-03-11 Cree, Inc. Light emitting devices having roughened/reflective contacts and methods of fabricating same
US8471269B2 (en) 2004-07-27 2013-06-25 Cree, Inc. Light emitting devices having roughened/reflective contacts and methods of fabricating same
US20090250716A1 (en) * 2004-07-27 2009-10-08 Kevin Haberern Light emitting devices having roughened/reflective contacts and methods of fabricating same
US20090184329A1 (en) * 2004-07-29 2009-07-23 Showa Denko K.K. Positive electrode for semiconductor light-emitting device
US8115212B2 (en) 2004-07-29 2012-02-14 Showa Denko K.K. Positive electrode for semiconductor light-emitting device
US7973325B2 (en) 2004-10-07 2011-07-05 Samsung Electronics Co., Ltd. Reflective electrode and compound semiconductor light emitting device including the same
US20060081867A1 (en) * 2004-10-07 2006-04-20 Samsung Electronics Co., Ltd. Reflective electrode and compound semiconductor light emitting device including the same
US7800126B2 (en) 2004-11-04 2010-09-21 Sharp Kabushiki Kaisha III-V group compound semiconductor light emitting device and manufacturing method thereof
US20060102933A1 (en) * 2004-11-04 2006-05-18 Kensaku Yamamoto III-V Group compound semiconductor light emitting device and manufacturing method thereof
US20060113548A1 (en) * 2004-11-29 2006-06-01 Ching-Chung Chen Light emitting diode
US20060157859A1 (en) * 2005-01-19 2006-07-20 Chih-Chen Chou Led packaging method and package structure
US7919784B2 (en) * 2005-09-30 2011-04-05 Lattice Power (Jiangxi) Corporation Semiconductor light-emitting device and method for making same
US20080230792A1 (en) * 2005-10-27 2008-09-25 Lattice Power (Jiangxi) Corporation Semiconductor Light-Emitting Device with Electrode for N-Polar Ingaain Surface
US11297705B2 (en) 2007-10-06 2022-04-05 Lynk Labs, Inc. Multi-voltage and multi-brightness LED lighting devices and methods of using same
US11317495B2 (en) 2007-10-06 2022-04-26 Lynk Labs, Inc. LED circuits and assemblies
US11729884B2 (en) 2007-10-06 2023-08-15 Lynk Labs, Inc. LED circuits and assemblies
US7994515B2 (en) * 2008-01-30 2011-08-09 Foxsemicon Integrated Technology, Inc. Light emitting device with high light extraction efficiency
US20090189167A1 (en) * 2008-01-30 2009-07-30 Foxsemicon Integrated Technology, Inc. Light emitting device with high light extraction efficiency
US20090290355A1 (en) * 2008-05-20 2009-11-26 Tae-Geun Kim Light-emitting device including reflective layer formed with curved surface and manufacturing method thereof
US8113903B2 (en) * 2008-05-20 2012-02-14 Korea University Industrial & Academic Collaboration Foundation Fabrication method of light-emitting device
US10411177B2 (en) 2008-08-18 2019-09-10 Epistar Corporation Light emitting device
US20110037089A1 (en) * 2009-04-03 2011-02-17 Mitsuaki Oya Nitride-based semiconductor device and method for fabricating the same
US8299490B2 (en) 2009-04-03 2012-10-30 Panasonic Corporation Nitride-based semiconductor device having electrode on m-plane
US8334199B2 (en) 2009-04-03 2012-12-18 Panasonic Corporation Method for fabricating nitride-based semiconductor device having electrode on m-plane
US8304802B2 (en) 2009-04-03 2012-11-06 Panasonic Corporation Nitride-based semiconductor device having electrode on m-plane
US20110037088A1 (en) * 2009-04-03 2011-02-17 Mitsuaki Oya Nitride-based semiconductor device and method for fabricating the same
US8318594B2 (en) 2009-04-03 2012-11-27 Panasonic Corporation Method for fabricating nitride-based semiconductor device having electrode on m-plane
US20120199863A1 (en) * 2009-06-25 2012-08-09 Koninklijke Philips Electronics N.V. Contact for a semiconductor light emitting device
US11695099B2 (en) * 2009-06-25 2023-07-04 Lumileds Llc Contact for a semiconductor light emitting device
US8124986B2 (en) 2010-01-18 2012-02-28 Panasonic Corporation Nitride-based semiconductor device and method for fabricating the same
US8933543B2 (en) 2010-04-02 2015-01-13 Panasonic Intellectual Property Management Co., Ltd. Nitride semiconductor element having m-plane angled semiconductor region and electrode including Mg and Ag
US8895419B2 (en) 2011-07-06 2014-11-25 Panasonic Corporation Nitride semiconductor light-emitting element and method for fabricating the same
US11284491B2 (en) 2011-12-02 2022-03-22 Lynk Labs, Inc. Color temperature controlled and low THD LED lighting devices and systems and methods of driving the same
US9847460B2 (en) 2012-05-17 2017-12-19 Epistar Corporation Light emitting device with reflective electrode
US9306124B2 (en) 2012-05-17 2016-04-05 Epistar Corporation Light emitting device with reflective electrode
US11677046B2 (en) 2012-11-02 2023-06-13 Epistar Corporation Electrode structure of light emitting device
US11437547B2 (en) 2012-11-02 2022-09-06 Epistar Corporation Electrode structure of light emitting device
US10847682B2 (en) 2012-11-02 2020-11-24 Epistar Corporation Electrode structure of light emitting device
US9865781B2 (en) * 2014-03-28 2018-01-09 Nichia Corporation Method for manufacturing light emitting device comprising lens with tapered profile
US20150280052A1 (en) * 2014-03-28 2015-10-01 Nichia Corporation Method for manufacturing light emitting device
US20160072004A1 (en) * 2014-09-05 2016-03-10 Samsung Electronics Co., Ltd. Semiconductor light emitting device
US11566759B2 (en) 2017-08-31 2023-01-31 Lynk Labs, Inc. LED lighting system and installation methods
US11749784B2 (en) 2018-10-23 2023-09-05 Seoul Viosys Co., Ltd. Flip chip type light emitting device

Also Published As

Publication number Publication date
CN101183699A (en) 2008-05-21
US7355212B2 (en) 2008-04-08
US20030209720A1 (en) 2003-11-13
EP1168460A3 (en) 2006-10-11
US20050051786A1 (en) 2005-03-10
US6825502B2 (en) 2004-11-30
US20050040420A1 (en) 2005-02-24
CN100587985C (en) 2010-02-03
KR20040010419A (en) 2004-01-31
US7138665B2 (en) 2006-11-21
US20050056857A1 (en) 2005-03-17
KR100469312B1 (en) 2005-02-02
CN100459183C (en) 2009-02-04
US20050035363A1 (en) 2005-02-17
US20050040423A1 (en) 2005-02-24
KR20020003101A (en) 2002-01-10
US7221002B2 (en) 2007-05-22
JP2002026392A (en) 2002-01-25
US20050037527A1 (en) 2005-02-17
US7179671B2 (en) 2007-02-20
US7135714B2 (en) 2006-11-14
CN1591918A (en) 2005-03-09
JP4024994B2 (en) 2007-12-19
CN1196205C (en) 2005-04-06
CN1330416A (en) 2002-01-09
TW531902B (en) 2003-05-11
US20050218419A1 (en) 2005-10-06
US7138664B2 (en) 2006-11-21
EP1168460A2 (en) 2002-01-02
KR100503907B1 (en) 2005-07-27

Similar Documents

Publication Publication Date Title
US7355212B2 (en) Light emitting element
US6586875B1 (en) Light emitting diode with low-temperature solder layer
US7268371B2 (en) Light extraction from a semiconductor light emitting device via chip shaping
US7319247B2 (en) Light emitting-diode chip and a method for producing same
US9472713B2 (en) Semiconductor light-emitting device
US6803603B1 (en) Semiconductor light-emitting element
US20080237616A1 (en) Semiconductor light emitting device and method for manufacturing the same
US7148521B2 (en) Semiconductor light emitting device and method of manufacturing the same
US20050035355A1 (en) Semiconductor light emitting diode and semiconductor light emitting device
JP4564234B2 (en) Semiconductor light emitting device
JP2001144321A (en) Light-emitting device and manufacturing method therefor
US20020055218A1 (en) Light emitting diode and fabricating method thereof
JP4625827B2 (en) Semiconductor light emitting device and semiconductor light emitting device
JP3400110B2 (en) Light emitting diode
CN109952659B (en) Iii-P light emitting devices with superlattices

Legal Events

Date Code Title Description
AS Assignment

Owner name: KABUSHIKI KAISHA TOSHIBA, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OKAZAKI, HARUHIKO;SUGAWARA, HIDETO;REEL/FRAME:011951/0488

Effective date: 20010622

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION