US20080105880A1 - SILICON NITRIDE PASSIVATION WITH AMMONIA PLASMA PRETREAMENT FOR IMPROVING RELIABILITY OF AlGaN/GaN HEMTs - Google Patents
SILICON NITRIDE PASSIVATION WITH AMMONIA PLASMA PRETREAMENT FOR IMPROVING RELIABILITY OF AlGaN/GaN HEMTs Download PDFInfo
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- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 title claims abstract description 62
- 229910002704 AlGaN Inorganic materials 0.000 title claims abstract description 29
- 229910021529 ammonia Inorganic materials 0.000 title claims abstract description 29
- 238000002161 passivation Methods 0.000 title claims abstract description 20
- 229910052581 Si3N4 Inorganic materials 0.000 title description 26
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 title description 25
- 230000004888 barrier function Effects 0.000 claims abstract description 18
- 230000015556 catabolic process Effects 0.000 claims abstract description 7
- 238000006731 degradation reaction Methods 0.000 claims abstract description 7
- 239000000758 substrate Substances 0.000 claims description 10
- 230000008021 deposition Effects 0.000 claims description 7
- 238000000034 method Methods 0.000 abstract description 9
- 229910002601 GaN Inorganic materials 0.000 description 22
- 238000000151 deposition Methods 0.000 description 6
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- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 238000009616 inductively coupled plasma Methods 0.000 description 3
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 3
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005137 deposition process Methods 0.000 description 2
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- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- 241001125929 Trisopterus luscus Species 0.000 description 1
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- RNQKDQAVIXDKAG-UHFFFAOYSA-N aluminum gallium Chemical compound [Al].[Ga] RNQKDQAVIXDKAG-UHFFFAOYSA-N 0.000 description 1
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- 238000011065 in-situ storage Methods 0.000 description 1
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/76—Unipolar devices, e.g. field effect transistors
- H01L29/772—Field effect transistors
- H01L29/778—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface
- H01L29/7786—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT
- H01L29/7787—Field effect transistors with two-dimensional charge carrier gas channel, e.g. HEMT ; with two-dimensional charge-carrier layer formed at a heterojunction interface with direct single heterostructure, i.e. with wide bandgap layer formed on top of active layer, e.g. direct single heterostructure MIS-like HEMT with wide bandgap charge-carrier supplying layer, e.g. direct single heterostructure MODFET
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/66007—Multistep manufacturing processes
- H01L29/66075—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials
- H01L29/66227—Multistep manufacturing processes of devices having semiconductor bodies comprising group 14 or group 13/15 materials the devices being controllable only by the electric current supplied or the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched, e.g. three-terminal devices
- H01L29/66409—Unipolar field-effect transistors
- H01L29/66446—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET]
- H01L29/66462—Unipolar field-effect transistors with an active layer made of a group 13/15 material, e.g. group 13/15 velocity modulation transistor [VMT], group 13/15 negative resistance FET [NERFET] with a heterojunction interface channel or gate, e.g. HFET, HIGFET, SISFET, HJFET, HEMT
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/20—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds
- H01L29/2003—Nitride compounds
Definitions
- This invention pertains to improving reliability of heterojunction transistors, particularly high electron mobility transistors, with an ammonia plasma pretreatment prior to passivation.
- AlGaN/GaN high electron mobility transistors have shown exceptional microwave power output densities, with a recently reported continuous wave power density of 30 W/mm and 50% power added efficiency at a frequency of 8 GHz, In addition, a 36-mm gate-width GaN HEMT has been demonstrated with a total power output of 150 W and a power added efficiency of 54%.
- device reliability remains a major concern for III-N HEMTs. In AlGaN/GaN HEMTs, degradation of the dc, transient, and microwave characteristics are often seen after relatively short periods of normal device operation. Although reliability is improving, microwave power output typically degrades by more than 1 dB in less than 1000 hours of operation.
- Another object of this invention is to pretreat an AlGaN/GaN transistor with a low-power ammonia plasma prior to silicon nitride deposition for high power applications.
- Another object of this invention is to improve reliability of an AlGaN/Gan transistor adapted for use in radars and communication equipment.
- Another object of this invention is to improve reliability of AlGaN/GaN HEMTS characterized by the presence of 2 DEG channel.
- Another object of this invention is prevention of drain current collapse caused by electron traps.
- Another object of this invention relates to reduction of surface and bulk traps in high power and high electron mobility AlGaN/GaN heterojunction transistors that can potentially operate at voltages exceeding 100 volts and with electron mobility in excess of 1000 cm 2 /v sec.
- FIG. 1 is a cross-sectional schematic representation of a high mobility transistor with AlGaN, GaN and doped GaN layers deposited on a silicon carbide substrate.
- FIGS. 2 ( a ) and ( b ) show induced current collapse of unpassivated HEMT in (a) before stress and after stress and in (b) of passivated HEMT devices with silicon nitride only and with silicon nitride passivation, stressed for 60 hours and 176 hours, respectively.
- FIG. 3 is a plot of normalized Drain Current versus Time, showing drain current response to pulsed gate voltage, in (a) with no passivation; in (b) for the same device after 64-hour stress; in (c) silicon nitride passivated device after 80-hour stress; and in (d) a device pretreated with ammonia plasma and passivated with silicon nitride, after 176-hour stress.
- FIG. 4 is a plot of power _P out versus Time showing rf output degradation of (a) passivated device with silicon nitride only and (b) pre-treated with ammonia plasma and coated or pre-treated with silicon nitride wherein stress conditions were 20v, 200 mA/mm operated at 2 GHz at 1 dB compression of the gain.
- the purpose of this invention is to improve the reliability of aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors by incorporating an ammonia (NH 3 ) plasma pre-treatment prior to silicon nitride (SiN) passivation of the heterojunction transistors after all other processing has been completed.
- AlGaN/GaN aluminum gallium nitride/gallium nitride
- SiN silicon nitride
- This invention pertains to an electronic device and to a method for making it.
- the device is a heterojunction transistor, particularly a high electron mobility transistor characterized by the presence of a 2 DEG channel.
- Transistors of this invention contain an AlGaN barrier and a GaN buffer, with the channel disposed, when present, at the interface of the barrier and the buffer.
- the method pertains to treatment of the device with ammonia plasma prior to passivation to extend reliability of the device beyond a period of time on the order of 300 hours of operation, the device typically being a 2 DEG AlGaN/GaN high electron mobility transistor with essentially no gate lag and with essentially no rf power output degradation.
- an in-situ ammonia plasma treatment is used before a silicon nitride deposition on an Al x Ga 1-x N/GaN (where x is 0.20 to 0.30), after all other processing has been completed.
- the ammonia plasma pretreatment and the silicon nitride deposition can both be performed in a plasma enhanced chemical vapor deposition system.
- the substrate temperature is maintained at 250° C. for both.
- a relatively low 35 W power level is typically used.
- resulting process parameters are 200 mT chamber pressure, 400 sccm N 2 +SiH 4 (95:5) gas flow, 9 sccm ammonia gas flow, 35 W ICP power, and OW RIE power.
- a silicon nitride film thickness of 750 A is adequate, with an optical index (n) of approximately 2.0, which indicates the approximate composition of the Si 3 N 4 passivation layer.
- the nitride deposition process was performed after all of the processing steps and was followed by etching openings to the metal contacts and deposition and patterning of a Ti—Au overlay metal.
- the ammonia plasma pretreatment and the silicon nitride deposition were performed in an inductively coupled plasma (ICP) configured plasma-enhanced chemical vapor deposition system with a bottom electrode diameter of 8 inches.
- ICP inductively coupled plasma
- the silicon nitride film, using about 5% by volume SiH 4 in a balance of N 2 was formed using a SiH 4 :NH 3 :N 2 plasma recipe (N 2 +SiH 4 of 300 to 400 sccm; NH 3 of 9 to 16 sccm).
- the substrate temperature was maintained at 250° C.
- the silicon nitride film thickness and the refractive index were measured by ellipsometry, and were 740-800 A and 2.03-2.09, respectively, for different device runs.
- the chamber pressure was 50 mT and the duration was 180 seconds.
- the ICP power was set to 35 W at 13.56 MHz, while the bottom electrode was set to 0 W.
- FIG. 1 shows a cross-sectional schematic transistor 10 containing barrier layer 12 disposed on channel 14 , which is followed by channel/buffer layer 16 , which in turn is disposed on buffer layer 17 , and which in turn is disposed on substrate 18 .
- the substrate supports all of the layers of the transistor.
- the barrier layer is AlGaN and the buffer/channel layer is GaN with the channel layer being at the interface of the barrier and the buffer/channel layers.
- the channel has a thickness on the order of 50 A to 100 A. It is the 2 DEG channel layer that characterizes a high electron mobility transistor, with electron mobility being in excess of 1000 cm 2 /V sec.
- the 2-DEG is formed at the interface of the buffer/channel and the barrier layers.
- contact 20 which provides electrical connection to source 24 , barrier layer 12 , and buffer/channel layer 16 .
- contact 22 provides electrical connection to drain 26 , barrier layer 12 , and buffer/channel layer 16 .
- Source 24 , drain 26 , and gate 28 are disposed in top layer 30 . Purpose of the source is to provide electrons to the transistor device. These electrons flow through the interface 2 DEG between the barrier layer and the buffer/channel layer to the drain. The gate controls the flow of these electrons through the 2 DEG.
- the source, the drain and the ohmic contacts 20 , 22 , 24 and 26 are typically Ti—Al—Ni—Au and the gate is typically Ni—Au.
- Typical barrier layer thickness is 200 A 300 A
- typical channel layer thickness is 50 A to 100 A
- typical buffer/channel layer thickness is 1 ⁇ m to 3 ⁇ m
- typical buffer layer thickness is 500 A to 1500 A
- typical substrate thickness is 1 ⁇ m to 2 ⁇ m.
- FIGS. 2 ( a ) and ( b ) are the measured drain current for three consecutive sweeps of V DS from 0 to 30V with V GS held at 0 V.
- the characteristics in FIG. 2 ( a ) are for an AlGaN/GaN HEMT without silicon nitride passivation prior to dc bias stress.
- the three traces are nearly coincident, as they should be.
- the second and third traces depart significantly from the first trace.
- FIGS. 3 ( a - d ) Corresponding results are seen with gate lag measurements as shown in FIGS. 3 ( a - d ).
- the drain current pulse shown in each figure is normalized to the steady state value of drain current.
- the ideal response characteristic is for the pulsed current to rise to the steady state value, as shown in FIG. 2 ( d ).
- Only the ammonia plasma plus silicon nitride processed device shows the ideal characteristic after bias stress. These characteristics again indicate that additional trapping levels are present after dc bias stress and that the ammonia plasma step is effective in suppressing their generation.
- the radio frequency (rf) degradation rate in dB/hour, is also improved by more than 100 times for the ammonia pretreated sample as compared to devices on the same split wafer with silicon nitride only.
- FIG. 4 shows the change in Pout, normalized to its initial value, versus hours of rf bias stress.
- the pre-treated device shows little drop to 70 hours with a Pin of 7 dBm, while the silicon nitride only device is degrading in the first 16 hours at Pin of 5 dBm, then even more rapidly after Pin was increased to 7 dBm.
- ammonia plasma provides hydrogen (H) atoms at the AlGaN surface. Passivation of surface defects by hydrogen has been used extensively in the past for silicon and gallium arsenide technologies. Hydrogen has been found to penetrate well into the AlGaN and reduce the density of bulk n-AlGaN deep level traps. These traps are thought to play a leading role in the current collapse phenomena.
- Ammonia plasma ionizes gas into charged particles that cause the surface to be cleaned and/or charged, as is well known.
- the chamber used herein for ammonia plasma treatment was a typical for semiconductor equipment manufacturers. Treatment duration was 3 minutes, although it can be higher or lower, but is typically in the range of 3-5 minutes. Other parameters that may be used to produce the desired ammonia plasma include power of 10-35 watts, ammonia flow rate of 30 to 70 sccm. Plasma frequency is 13.56 MHz.
- Rf stress conditions included conditions for dc bias and a microwave signal that goes into the device.
- the input power of this signal is typically 10-15 dBM at a frequency of 2-12 GHz.
- the dc stress conditions include drain voltage typically of 20-30 volts and a drain current typically of 100-300 mA/mm.
Abstract
This invention pertains to an electronic device and to a method for making it. The device is a heterojunction transistor, particularly a high electron mobility transistor, characterized by presence of a 2 DEG channel. Transistors of this invention contain an AlGaN barrier and a GaN buffer, with the channel disposed, when present, at the interface of the barrier and the buffer. Surface treated with ammonia plasma resembles untreated surface. The method pertains to treatment of the device with ammonia plasma prior to passivation to extend reliability of the device beyond a period of time on the order of 300 hours of operation, the device typically being a 2 DEG AlGaN/GaN high electron mobility transistor with essentially no gate lag and with essentially no rf power output degradation.
Description
- This application is a divisional application of U.S. application Ser. No. 11/311,592, filed Dec. 9, 2005.
- 1. Field of the Invention
- This invention pertains to improving reliability of heterojunction transistors, particularly high electron mobility transistors, with an ammonia plasma pretreatment prior to passivation.
- 2. Description of Related Art
- Prior methods which have been used to prepare processed AlGaN/GaN high electron mobility transistors (HEMTs) for reliable operation in the past have included using no passivation at all, or direct deposition of a variety of electrically insulating materials intended to passivate surface states. These material films can be deposited by such processes as plasma enhanced chemical vapor deposition. Silicon nitride (SiN) is one of the most commonly used surface passivating films for AlGaN/GaN HEMTs and can be deposited onto the device by the aforementioned method. However, silicon nitride passivation, while an improvement over no passivation at all, still results in a decrease in performance of the device after dc and rf bias stress. This is a significant limitation and disadvantage in the reliability of AlGaN/GaN HEMT electronic devices.
- AlGaN/GaN high electron mobility transistors have shown exceptional microwave power output densities, with a recently reported continuous wave power density of 30 W/mm and 50% power added efficiency at a frequency of 8 GHz, In addition, a 36-mm gate-width GaN HEMT has been demonstrated with a total power output of 150 W and a power added efficiency of 54%. However, device reliability remains a major concern for III-N HEMTs. In AlGaN/GaN HEMTs, degradation of the dc, transient, and microwave characteristics are often seen after relatively short periods of normal device operation. Although reliability is improving, microwave power output typically degrades by more than 1 dB in less than 1000 hours of operation.
- It is an object of this invention to pretreat an AlGaN/GaN heterojunction field effect transistor with ammonia plasma prior to passivation in order to improve reliability thereof.
- Another object of this invention is to pretreat an AlGaN/GaN transistor with a low-power ammonia plasma prior to silicon nitride deposition for high power applications.
- Another object of this invention is to improve reliability of an AlGaN/Gan transistor adapted for use in radars and communication equipment.
- Another object of this invention is to improve reliability of AlGaN/GaN HEMTS characterized by the presence of 2 DEG channel.
- Another object of this invention is prevention of drain current collapse caused by electron traps.
- Another object of this invention relates to reduction of surface and bulk traps in high power and high electron mobility AlGaN/GaN heterojunction transistors that can potentially operate at voltages exceeding 100 volts and with electron mobility in excess of 1000 cm2/v sec.
- These and other objects of this invention can be attained by pretreatment of a 2 DEG AlGaN/GaN heterojunction transistor with a low-power ammonia plasma prior to passivation.
-
FIG. 1 is a cross-sectional schematic representation of a high mobility transistor with AlGaN, GaN and doped GaN layers deposited on a silicon carbide substrate. - FIGS. 2 (a) and (b) show induced current collapse of unpassivated HEMT in (a) before stress and after stress and in (b) of passivated HEMT devices with silicon nitride only and with silicon nitride passivation, stressed for 60 hours and 176 hours, respectively.
-
FIG. 3 is a plot of normalized Drain Current versus Time, showing drain current response to pulsed gate voltage, in (a) with no passivation; in (b) for the same device after 64-hour stress; in (c) silicon nitride passivated device after 80-hour stress; and in (d) a device pretreated with ammonia plasma and passivated with silicon nitride, after 176-hour stress. -
FIG. 4 is a plot of power _Pout versus Time showing rf output degradation of (a) passivated device with silicon nitride only and (b) pre-treated with ammonia plasma and coated or pre-treated with silicon nitride wherein stress conditions were 20v, 200 mA/mm operated at 2 GHz at 1 dB compression of the gain. - The purpose of this invention, in a preferred embodiment, is to improve the reliability of aluminum gallium nitride/gallium nitride (AlGaN/GaN) high electron mobility transistors by incorporating an ammonia (NH3) plasma pre-treatment prior to silicon nitride (SiN) passivation of the heterojunction transistors after all other processing has been completed.
- This invention pertains to an electronic device and to a method for making it. The device is a heterojunction transistor, particularly a high electron mobility transistor characterized by the presence of a 2 DEG channel. Transistors of this invention contain an AlGaN barrier and a GaN buffer, with the channel disposed, when present, at the interface of the barrier and the buffer. The method pertains to treatment of the device with ammonia plasma prior to passivation to extend reliability of the device beyond a period of time on the order of 300 hours of operation, the device typically being a 2 DEG AlGaN/GaN high electron mobility transistor with essentially no gate lag and with essentially no rf power output degradation.
- Pursuant to one embodiment of the method, an in-situ ammonia plasma treatment is used before a silicon nitride deposition on an Alx Ga1-xN/GaN (where x is 0.20 to 0.30), after all other processing has been completed. The ammonia plasma pretreatment and the silicon nitride deposition can both be performed in a plasma enhanced chemical vapor deposition system. The substrate temperature is maintained at 250° C. for both. For the ammonia plasma pretreatment, a relatively low 35 W power level is typically used. An example of resulting process parameters are 200 mT chamber pressure, 400 sccm N2+SiH4 (95:5) gas flow, 9 sccm ammonia gas flow, 35 W ICP power, and OW RIE power. A silicon nitride film thickness of 750 A is adequate, with an optical index (n) of approximately 2.0, which indicates the approximate composition of the Si3N4 passivation layer.
- The nitride deposition process was performed after all of the processing steps and was followed by etching openings to the metal contacts and deposition and patterning of a Ti—Au overlay metal. The ammonia plasma pretreatment and the silicon nitride deposition were performed in an inductively coupled plasma (ICP) configured plasma-enhanced chemical vapor deposition system with a bottom electrode diameter of 8 inches. The silicon nitride film, using about 5% by volume SiH4 in a balance of N2, was formed using a SiH4:NH3:N2 plasma recipe (N2+SiH4 of 300 to 400 sccm; NH3 of 9 to 16 sccm). The substrate temperature was maintained at 250° C. for both the ammonia plasma pretreatment and the silicon nitride deposition processes. The silicon nitride film thickness and the refractive index were measured by ellipsometry, and were 740-800 A and 2.03-2.09, respectively, for different device runs. For the pretreatment, the chamber pressure was 50 mT and the duration was 180 seconds. The ICP power was set to 35 W at 13.56 MHz, while the bottom electrode was set to 0 W.
- The invention can be described in connection with
FIGS. 1-4 whereinFIG. 1 shows a cross-sectionalschematic transistor 10 containingbarrier layer 12 disposed onchannel 14, which is followed by channel/buffer layer 16, which in turn is disposed onbuffer layer 17, and which in turn is disposed onsubstrate 18. The substrate supports all of the layers of the transistor. The barrier layer is AlGaN and the buffer/channel layer is GaN with the channel layer being at the interface of the barrier and the buffer/channel layers. The channel has a thickness on the order of 50 A to 100 A. It is the 2 DEG channel layer that characterizes a high electron mobility transistor, with electron mobility being in excess of 1000 cm2/V sec. There is a layer of AlN between the buffer/layer and the substrate layers. The 2-DEG is formed at the interface of the buffer/channel and the barrier layers. - Completing the schematic transistor of
FIG. 1 iscontact 20 which provides electrical connection tosource 24,barrier layer 12, and buffer/channel layer 16. Likewise,contact 22 provides electrical connection to drain 26,barrier layer 12, and buffer/channel layer 16.Source 24,drain 26, andgate 28 are disposed intop layer 30. Purpose of the source is to provide electrons to the transistor device. These electrons flow through the interface 2 DEG between the barrier layer and the buffer/channel layer to the drain. The gate controls the flow of these electrons through the 2 DEG. The source, the drain and theohmic contacts - Shown in FIGS. 2 (a) and (b) are the measured drain current for three consecutive sweeps of VDS from 0 to 30V with VGS held at 0 V. The characteristics in
FIG. 2 (a) are for an AlGaN/GaN HEMT without silicon nitride passivation prior to dc bias stress. For the non-stressed device (solid lines), the three traces are nearly coincident, as they should be. But after dc bias stress for 64 hours with VDS=30V and IDS=200 mA/mm (dashed lines), the second and third traces depart significantly from the first trace. This reduction in drain current for the second and third traces is due to trapped charge in the structure as a result of hot electron injection caused at high drain voltages during the first sweep. This effect is present in the device after stress due to the generation or activation of defects during the 64 hour dc bias stress. It can be see inFIG. 2 (b), that a silicon nitride passivation layer does little to suppress this effect (dashed lines). But the key result, shown in the solid lines, is that an ammonia plasma treatment prior to passivation completely eliminates this effect for at least 176 hours of bias stress. - Corresponding results are seen with gate lag measurements as shown in FIGS. 3 (a-d). The gate lag measurements are for VDS=1 V and VGS=VTH−2 V, pulsed to VGS=0 V. The drain current pulse shown in each figure is normalized to the steady state value of drain current. The ideal response characteristic is for the pulsed current to rise to the steady state value, as shown in
FIG. 2 (d). Only the ammonia plasma plus silicon nitride processed device shows the ideal characteristic after bias stress. These characteristics again indicate that additional trapping levels are present after dc bias stress and that the ammonia plasma step is effective in suppressing their generation. - The radio frequency (rf) degradation rate, in dB/hour, is also improved by more than 100 times for the ammonia pretreated sample as compared to devices on the same split wafer with silicon nitride only.
FIG. 4 shows the change in Pout, normalized to its initial value, versus hours of rf bias stress. The pre-treated device shows little drop to 70 hours with a Pin of 7 dBm, while the silicon nitride only device is degrading in the first 16 hours at Pin of 5 dBm, then even more rapidly after Pin was increased to 7 dBm. - An added benefit of the invention is believed to be that the ammonia plasma provides hydrogen (H) atoms at the AlGaN surface. Passivation of surface defects by hydrogen has been used extensively in the past for silicon and gallium arsenide technologies. Hydrogen has been found to penetrate well into the AlGaN and reduce the density of bulk n-AlGaN deep level traps. These traps are thought to play a leading role in the current collapse phenomena.
- Ammonia plasma ionizes gas into charged particles that cause the surface to be cleaned and/or charged, as is well known. The chamber used herein for ammonia plasma treatment was a typical for semiconductor equipment manufacturers. Treatment duration was 3 minutes, although it can be higher or lower, but is typically in the range of 3-5 minutes. Other parameters that may be used to produce the desired ammonia plasma include power of 10-35 watts, ammonia flow rate of 30 to 70 sccm. Plasma frequency is 13.56 MHz.
- Rf stress conditions included conditions for dc bias and a microwave signal that goes into the device. The input power of this signal is typically 10-15 dBM at a frequency of 2-12 GHz. The dc stress conditions include drain voltage typically of 20-30 volts and a drain current typically of 100-300 mA/mm.
- In conclusion, reliability of AlGaN—GaN high eletron mobility transistors that exhibit induced trapping effects due to extended dc bias or microwave operation has been improved by the incorporation of an ammonia plasma treatment prior to passivation. This processing step suppresses increases in current collapse and eliminates gate lag reductions after extended dc bias and significantly lessens degradation under microwave operation. It is believed that the interaction of the plasma with the exposed surface and H ions and/or atoms diffusion into the epitaxial layers are responsible for the improved device characteristics after extended dc bias and microwave operation.
- While presently embodiments of the invention have been shown of the novel transistors and treatment with ammonia plasma, and of the several modifications discussed, persons skilled in this art will readily appreciate that various additional changes and modifications can be made without departing from the spirit of the invention as defined and differentiated by the following claims.
Claims (12)
1. A high electron mobility transistor, comprising:
a substrate;
a GaN buffer layer disposed on the substrate;
an AlGaN barrier layer disposed on the GaN buffer layer such that a 2 DEG channel is disposed at the interface of the AlGaN barrier layer and GaN buffer layer; and
a passivation layer disposed on the AlGaN barrier layer, wherein an upper surface of the AlGaN barrier layer has been pre-treated with an ammonia plasma prior to a deposition of the passivation layer.
2. The transistor of claim 1 , wherein the transistor has essentially no measurable drain current collapse for up to about 176 hours of dc bias stress.
3. The transistor of claim 1 , wherein the transistor has essentially no measurable gate lag for up to about 176 hours of dc bias stress.
4. The transistor of claim 2 , wherein the dc bias stress is characterized by a drain current of 100-300 mA/mm and a drain voltage of about 23-30 volts.
5. The transistor of claim 2 , wherein the dc bias stress is provided by a microwave signal having an input power Pin of 5-20 dBm at a frequency of 2-12 GHz.
6. The transistor of claim 1 , wherein the AlGaN barrier layer is about 150 A to 300 A thick.
7. The transistor of claim 1 , wherein the GaN buffer layer is about 5000 μm to 15,000 μm thick.
8. The transistor of claim 1 , wherein the transistor has experienced essentially no decrease in rf power output (Pout) up to about 70 hours.
9. The transistor of claim 1 , wherein the AlGaN barrier layer is made from AlxGa1-xN, wherein 0.15≦x≦0.40.
10. The transistor of claim 1 , wherein the rate of degradation of microwave power output, while under continuous microwave operation, is at least 100 times smaller than a conventional high electron mobility transistor that is not pre-treated with ammonia plasma.
11. The transistor of claim 1 , wherein the transistor has electron mobility in excess of 1000 cm2/V sec.
12. The transistor of claim 1 , further comprising a AlN buffer layer disposed between the GaN buffer layer and the substrate.
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US20100304042A1 (en) * | 2009-05-31 | 2010-12-02 | Hsiu-Lien Liao | Method for forming superhigh stress layer |
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Citations (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5179029A (en) * | 1990-02-07 | 1993-01-12 | At&T Bell Laboratories | Hydrogen plasma passivation of GaAs |
US5464664A (en) * | 1992-06-16 | 1995-11-07 | At&T Ipm Corp. | Downstream ammonia plasma passivation of GaAs |
US5764673A (en) * | 1995-09-25 | 1998-06-09 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor light emitting device |
US5913149A (en) * | 1992-12-31 | 1999-06-15 | Micron Technology, Inc. | Method for fabricating stacked layer silicon nitride for low leakage and high capacitance |
US20020142622A1 (en) * | 2001-03-28 | 2002-10-03 | Kabushiki Kaisha Toshiba | Method of manufacturing semiconductor device having buried metal wiring |
US20030017692A1 (en) * | 1999-08-10 | 2003-01-23 | Hitachi, Ltd. | Semiconductor integrated circuit device and manufacturing method of semiconductor integrated circuit device |
US20030020092A1 (en) * | 2001-07-24 | 2003-01-30 | Primit Parikh | Insulating gate AlGaN/GaN HEMT |
US20030157815A1 (en) * | 2000-08-30 | 2003-08-21 | Weimer Ronald A. | Ammonia gas passivation on nitride encapsulated devices |
US6737683B2 (en) * | 2002-02-28 | 2004-05-18 | Matsushita Electric Industrial Co., Ltd. | Semiconductor device composed of a group III-V nitride semiconductor |
US20040232440A1 (en) * | 2003-05-21 | 2004-11-25 | Sanken Electric Co., Ltd. | Compound semiconductor substrates and method of fabrication |
US20050258451A1 (en) * | 2004-05-20 | 2005-11-24 | Saxler Adam W | Methods of fabricating nitride-based transistors having regrown ohmic contact regions and nitride-based transistors having regrown ohmic contact regions |
US20060076577A1 (en) * | 2004-09-30 | 2006-04-13 | Boos John B | High electron mobility transistors with Sb-based channels |
US20060108606A1 (en) * | 2004-11-23 | 2006-05-25 | Saxler Adam W | Cap layers and/or passivation layers for nitride-based transistors, transistor structures and methods of fabricating same |
US20060226412A1 (en) * | 2005-04-11 | 2006-10-12 | Saxler Adam W | Thick semi-insulating or insulating epitaxial gallium nitride layers and devices incorporating same |
-
2005
- 2005-12-09 US US11/311,592 patent/US7338826B2/en not_active Expired - Fee Related
-
2007
- 2007-12-21 US US11/962,259 patent/US20080105880A1/en not_active Abandoned
Patent Citations (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5179029A (en) * | 1990-02-07 | 1993-01-12 | At&T Bell Laboratories | Hydrogen plasma passivation of GaAs |
US5464664A (en) * | 1992-06-16 | 1995-11-07 | At&T Ipm Corp. | Downstream ammonia plasma passivation of GaAs |
US5913149A (en) * | 1992-12-31 | 1999-06-15 | Micron Technology, Inc. | Method for fabricating stacked layer silicon nitride for low leakage and high capacitance |
US5764673A (en) * | 1995-09-25 | 1998-06-09 | Mitsubishi Denki Kabushiki Kaisha | Semiconductor light emitting device |
US20030017692A1 (en) * | 1999-08-10 | 2003-01-23 | Hitachi, Ltd. | Semiconductor integrated circuit device and manufacturing method of semiconductor integrated circuit device |
US20030157815A1 (en) * | 2000-08-30 | 2003-08-21 | Weimer Ronald A. | Ammonia gas passivation on nitride encapsulated devices |
US20020142622A1 (en) * | 2001-03-28 | 2002-10-03 | Kabushiki Kaisha Toshiba | Method of manufacturing semiconductor device having buried metal wiring |
US20030020092A1 (en) * | 2001-07-24 | 2003-01-30 | Primit Parikh | Insulating gate AlGaN/GaN HEMT |
US6737683B2 (en) * | 2002-02-28 | 2004-05-18 | Matsushita Electric Industrial Co., Ltd. | Semiconductor device composed of a group III-V nitride semiconductor |
US7122451B2 (en) * | 2002-02-28 | 2006-10-17 | Matsushita Electric Industrial Co., Ltd. | Method for fabricating a semiconductor device including exposing a group III-V semiconductor to an ammonia plasma |
US20040232440A1 (en) * | 2003-05-21 | 2004-11-25 | Sanken Electric Co., Ltd. | Compound semiconductor substrates and method of fabrication |
US20050258451A1 (en) * | 2004-05-20 | 2005-11-24 | Saxler Adam W | Methods of fabricating nitride-based transistors having regrown ohmic contact regions and nitride-based transistors having regrown ohmic contact regions |
US20060076577A1 (en) * | 2004-09-30 | 2006-04-13 | Boos John B | High electron mobility transistors with Sb-based channels |
US20060108606A1 (en) * | 2004-11-23 | 2006-05-25 | Saxler Adam W | Cap layers and/or passivation layers for nitride-based transistors, transistor structures and methods of fabricating same |
US20060226412A1 (en) * | 2005-04-11 | 2006-10-12 | Saxler Adam W | Thick semi-insulating or insulating epitaxial gallium nitride layers and devices incorporating same |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20100304042A1 (en) * | 2009-05-31 | 2010-12-02 | Hsiu-Lien Liao | Method for forming superhigh stress layer |
US20140318443A1 (en) * | 2011-07-25 | 2014-10-30 | Manutius Ip Inc. | Nucleation of aluminum nitride on a silicon substrate using an ammonia preflow |
US9617656B2 (en) * | 2011-07-25 | 2017-04-11 | Toshiba Corporation | Nucleation of aluminum nitride on a silicon substrate using an ammonia preflow |
US10174439B2 (en) | 2011-07-25 | 2019-01-08 | Samsung Electronics Co., Ltd. | Nucleation of aluminum nitride on a silicon substrate using an ammonia preflow |
US8921220B2 (en) | 2012-03-23 | 2014-12-30 | Samsung Electronics Co., Ltd. | Selective low-temperature ohmic contact formation method for group III-nitride heterojunction structured device |
US9117890B2 (en) | 2012-10-09 | 2015-08-25 | Samsung Electronics Co., Ltd. | High-electron mobility transistor and method of manufacturing the same |
US20170373177A1 (en) * | 2016-06-27 | 2017-12-28 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Semiconductor Device |
US10283630B2 (en) * | 2016-06-27 | 2019-05-07 | Fraunhofer-Gesellschaft Zur Forderung Der Angewandten Forschung E.V. | Semiconductor device |
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US7338826B2 (en) | 2008-03-04 |
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