WO2004029985A1 - 半導体記憶装置および携帯電子機器 - Google Patents
半導体記憶装置および携帯電子機器 Download PDFInfo
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- WO2004029985A1 WO2004029985A1 PCT/JP2003/011559 JP0311559W WO2004029985A1 WO 2004029985 A1 WO2004029985 A1 WO 2004029985A1 JP 0311559 W JP0311559 W JP 0311559W WO 2004029985 A1 WO2004029985 A1 WO 2004029985A1
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- voltage
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- input voltage
- input
- memory cell
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Classifications
-
- 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
- H01L29/66477—Unipolar field-effect transistors with an insulated gate, i.e. MISFET
- H01L29/66825—Unipolar field-effect transistors with an insulated gate, i.e. MISFET with a floating gate
-
- 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
- H01L29/40—Electrodes ; Multistep manufacturing processes therefor
- H01L29/401—Multistep manufacturing processes
- H01L29/4011—Multistep manufacturing processes for data storage electrodes
- H01L29/40114—Multistep manufacturing processes for data storage electrodes the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
-
- 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
- H01L29/78—Field effect transistors with field effect produced by an insulated gate
- H01L29/788—Field effect transistors with field effect produced by an insulated gate with floating gate
- H01L29/7887—Programmable transistors with more than two possible different levels of programmation
Definitions
- the present invention relates to a semiconductor memory device and a portable electronic device, and more particularly, to a semiconductor memory device having a memory cell array using a field effect transistor having a memory function as a memory cell, and a portable electronic device using the semiconductor memory device.
- a flash memory is typically used as a nonvolatile semiconductor memory device.
- a floating gate 902 an insulating film 907, and a word line (control gate) are formed on a semiconductor substrate 901 via a gate insulating film 908.
- 903 are formed in this order, and a source line 904 and a bit line 905 are formed on both sides of the floating gate 902 by a diffusion region to constitute a memory cell.
- An element isolation region 906 is formed around the memory cell (refer to Japanese Patent Application Laid-Open No. 5-304277).
- the memory cell holds the memory as the amount of charge in the floating gate 902.
- a memory cell array configured by arranging the above memory cells can perform a desired memory cell rewrite and read operation by selecting a specific read line and bit line and applying a predetermined voltage.
- a semiconductor memory device is a semiconductor memory device comprising: a gut electrode formed on a semiconductor layer via a gate insulating film; a channel region disposed under thecollect electrode; A memory element comprising a diffusion region arranged on both sides of the region and having a conductivity type opposite to that of the channel region and a memory function body formed on both sides of the gate electrode and having a function of retaining charges is used as a memory cell.
- a first switch in which an input voltage supplied from outside to the memory cell array is applied to an input terminal, and an output terminal is connected to an input terminal of the memory cell array.
- a second switch in which the input voltage is applied to the input terminal; a charge pump in which a pump input terminal is connected to the output terminal of the second switch; and a second switch in which the pump input terminal is connected to the pump output terminal of the charge pump.
- a third switch having a terminal connected thereto and an output terminal connected to an input terminal of the memory cell array; an input voltage determining circuit for determining whether the input voltage is equal to or lower than a predetermined voltage; And a control circuit for controlling on / off of the first, second, and third switches based on the determination result.
- the control circuit turns on the first switch and turns off the second and third switches. If it is determined that the voltage is equal to or lower than the predetermined voltage, the first switch is turned off and the second and third switches are turned on.
- the memory function body has a function capable of injecting and extracting electrons or holes.
- the field effect transistor is operated as a memory element by converting the difference in the amount of charge stored in the memory function body into the difference in the amount of current.
- the control circuit determines that the input voltage has exceeded a predetermined voltage
- the control circuit turns on the first switch and turns off the second and third switches, thereby reducing the input voltage.
- the data is supplied to the memory cell array via the first switch.
- the control circuit turns off the first switch and turns on the second and third switches.
- the voltage from the charge pump is supplied to the memory cell array via the third switch. Therefore, by using the above-described memory element, it is possible to realize a semiconductor memory device that can hold two bits of data even when miniaturized, can supply a sufficient current to the memory cell array, and can prevent a circuit malfunction.
- each of the first, second, and third switches includes: a first P-channel field-effect transistor whose source forms an input terminal; and a first P-channel field-effect transistor.
- the second P-channel field-effect transistor in which the drain is connected to the drain of the transistor and the source forms the output terminal, and the first P-channel field-effect transistor in response to a control signal from the control circuit are connected.
- First voltage level shifter selectively connected to either the source or ground
- a second voltage level shifter for selectively connecting the gate of the second P-channel field effect transistor to either the source or the ground or to a shift according to a control signal from the control circuit. It is characterized by having.
- the first, second, and third switches can be realized with a small circuit area, and perform an accurate circuit operation.
- the predetermined voltage is a voltage within a range of +3 V to +12 V.
- an appropriate voltage and a sufficient current can be supplied to a memory element as a memory cell constituting the memory cell array.
- an input terminal is connected to an output terminal of the first switch, and a voltage polarity inversion circuit that inverts the polarity of a voltage input to the input terminal and outputs the inverted voltage to the memory cell array. It is characterized by having.
- the semiconductor memory device of the above embodiment when a negative voltage is supplied to the good electrode at the time of erasing operation of the memory element as the memory cell, when a large current supply is not necessary, the positive polarity Is converted into a negative voltage, and a positive voltage is applied to the drain electrode and a negative electrode is applied to the good electrode, thereby enabling an efficient and reliable erasing operation with a small circuit area.
- the semiconductor memory device of the second invention includes a gate electrode formed on a semiconductor layer via a gate insulating film, a shell region arranged below the gate electrode, and both sides of the channel page region.
- a diffusion region having a conductivity type opposite to that of the channel region; and a memory function body formed on both sides of the good electrode and having a function of retaining charges.
- a first switch having a negative input voltage supplied from the outside to the memory cell array applied to an input terminal, an output terminal connected to the input terminal of the memory cell array, and the negative input voltage applied to the input terminal.
- a second switch applied to the second switch, a charge pump having a pump input terminal connected to an output terminal of the second switch, and a pump for the charge pump.
- the input voltage is whether or not a predetermined voltage or higher
- a control circuit that controls on / off of the first, second, and third switches based on the determination result of the input voltage determination circuit.
- the control circuit determines that the input voltage is less than the predetermined voltage
- the control circuit turns on the first switch and turns off the second and third switches.
- the first switch is turned off and the second and third switches are turned on.
- the same operation and effect can be obtained by the same circuit configuration as that of the semiconductor memory device of the first invention, and when a negative voltage is supplied to the memory cell array, a sufficient current Supply becomes possible.
- the first, second, and third switches each include a first N-channel field effect transistor whose source forms an input terminal, and a first N-channel field effect transistor.
- a second N-channel field-effect transistor having a drain connected to the drain of the transistor and a source forming an output terminal, and a gate of the first N-channel field-effect transistor in response to a control signal from the control circuit.
- a first voltage level shifter for selectively connecting the gate of the second N-channel field effect transistor to a source or ground according to a control signal from the control circuit.
- a second voltage level shifter selectively connected to one of the shifts.
- the first, second, and third switches can be realized with a small circuit area, and can perform an accurate circuit operation.
- the predetermined voltage is a voltage in a range of 13 V to 112 V.
- the semiconductor memory device of the above embodiment it is possible to supply an appropriate negative voltage and a sufficient current to a memory element as a memory cell constituting the memory cell array.
- the semiconductor memory device includes a gate electrode formed on a semiconductor layer with a gate insulating film interposed therebetween, a channel region disposed below the gate electrode, and disposed on both sides of the channel region.
- a diffusion region having a conductivity type opposite to that of the channel region;
- a memory element formed as a memory cell composed of a memory function body having a function of retaining charges formed on both sides of the gate electrode, and a positive input voltage supplied to the memory cell array from outside Is applied to the input terminal, the output terminal is connected to the input terminal of the memory cell array, the second switch is applied with the positive input voltage to the input terminal, the second switch,
- a first input voltage determination circuit that determines whether the positive input voltage is equal to or less than a first predetermined voltage, and a first input voltage determination circuit If it is determined that the positive input voltage has exceeded the first predetermined voltage, the first switch is turned on and the second and third switches are turned off, while the first input voltage determination circuit is turned on by the first input voltage determination circuit.
- a first control circuit that turns off the first switch and turns on the second and third switches when it is determined that the input voltage is equal to or lower than the first predetermined voltage.
- a negative input voltage externally supplied to the memory cell array is applied to an input terminal, an output terminal is connected to a fourth switch having an input terminal connected to the memory cell array, and the negative input voltage is input to the fourth switch.
- a sixth switch having an output terminal connected to the input terminal of the memory cell array; a second input voltage determination circuit for determining whether the negative input voltage is equal to or higher than a second predetermined voltage; If the input voltage determination circuit determines that the negative input voltage is lower than the second predetermined voltage, the second input voltage determination circuit turns on the fourth switch and turns off the fifth and sixth switches, while the second input A second control circuit for turning off the fourth switch and turning on the fifth and sixth switches when the voltage judgment circuit judges that the negative input voltage is equal to or higher than the second predetermined voltage.
- the same operation and effect can be obtained by the same circuit configuration as that of the semiconductor memory device according to the first aspect of the present invention.
- Current supply is possible.
- the semiconductor memory device includes the first, second, and third switches. Each has a first P-channel field-effect transistor whose source forms an input terminal, and a second P-channel field-effect transistor whose drain is connected to the drain of the first P-channel field effect transistor and whose source forms an output terminal. An effect transistor, and a first voltage level shifter that selectively connects a gate of the first P-channel field effect transistor to either the source or the ground according to a control signal from the first control circuit. A second voltage level shifter for selectively connecting the gate of the second P-channel field effect transistor to either the source or the ground in accordance with a control signal from the first control circuit.
- Each of the fourth, fifth and sixth switches has a drain connected to a first N-channel field-effect transistor whose source forms an input terminal and a drain of the first N-channel field-effect transistor.
- a second N-channel field effect transistor having a source forming an output terminal, and a gate of the first N-channel field effect transistor connected to a source or ground according to a control signal from the second control circuit.
- a third voltage level shifter selectively connected to one of the two, and a gate of the second N-channel field effect transistor, which is either a source or a ground, according to a control signal from the second control circuit.
- a fourth voltage level shifter selectively connected to either of them.
- the first to sixth switches can be realized with a small circuit area, and can perform an accurate circuit operation.
- the first predetermined voltage is a voltage within a range of +3 V to +12 V
- the second predetermined voltage is a voltage of 13 V to 12 V. It is characterized by a voltage within the range.
- both positive and negative voltages can be supplied at an appropriate voltage and a sufficient current can be supplied.
- the memory cell array, and a negative input voltage supplied from outside to the memory cell array is applied to the input terminal, and the output terminal is connected to the input terminal of the memory cell array.
- a third switch connected thereto, an input voltage determination circuit for determining whether or not the input voltage is equal to or higher than a predetermined voltage, and a first, second and third switch based on a determination result of the input voltage determination circuit.
- a control circuit for turning on and off the switches.
- the control circuit turns on the first switch and turns off the second and third switches, while the input voltage determining circuit determines that the input voltage is lower than the input voltage.
- the first switch is turned off and the second and third switches are turned on.
- the control circuit when the input voltage determination circuit determines that the negative input voltage is lower than the predetermined voltage, the control circuit turns on the first switch and sets the second and the second switches. By turning off the third switch, a negative input voltage is supplied to the memory cell array via the first switch.
- the control circuit when the input voltage determination circuit determines that the input voltage is equal to or higher than the predetermined voltage, the control circuit turns off the first switch and turns on the second and third switches, thereby providing the charge pump. Is supplied to the memory cell array via the third switch. Therefore, when a negative voltage is supplied to the memory cell array, a sufficient current can be supplied to the memory cell array, and a semiconductor memory device capable of preventing a circuit malfunction can be realized.
- a memory cell array and a memory cell array, wherein a positive input voltage supplied from outside to the memory cell array is applied to an input terminal, and an output terminal is connected to an input terminal of the memory cell array.
- a second switch in which the positive input voltage is applied to an input terminal
- a first charge pump in which a pump input terminal is connected to an output terminal of the second switch
- a third switch having an input terminal connected to the pump output terminal of the first charge pump, and an output terminal connected to the input terminal of the memory cell array; and the positive input voltage being equal to or lower than the first predetermined voltage.
- a first input voltage judgment circuit for judging whether or not the first input voltage judgment circuit turns on the first switch when the first input voltage judgment circuit judges that the positive input voltage has exceeded a first predetermined voltage. And While the second and third switches are turned off, when the first input voltage determination circuit determines that the positive input voltage is equal to or lower than the first predetermined voltage, the first switch is turned off and the second switch is turned off. And a first control circuit for turning on a third switch, and Is provided.
- a negative input voltage externally supplied to the memory cell array is applied to an input terminal, and a fourth switch having an output terminal connected to the input terminal of the memory cell array;
- a fifth switch applied to the input terminal, a second charge pump having a pump input terminal connected to the output terminal of the fifth switch, and an input terminal connected to a pump output terminal of the second charge pump;
- a sixth switch having an output terminal connected to the input terminal of the memory cell array, a second input voltage determination circuit for determining whether or not the negative input voltage is equal to or higher than a second predetermined voltage;
- the second input voltage determination circuit determines that the negative input voltage is lower than the second predetermined voltage
- the second input voltage determination circuit turns on the fourth switch and turns off the fifth and sixth switches.
- 2 input voltage A second control circuit that turns off the fourth switch and turns on the fifth and sixth switches when the constant circuit determines that the negative input voltage is equal to or higher than the second predetermined voltage.
- the first control circuit when the first input voltage determination circuit determines that the positive input voltage has exceeded the first predetermined voltage, the first control circuit turns on the first switch. Then, by turning off the second and third switches, a positive input voltage is supplied to the memory cell array via the first switch. On the other hand, if the first input voltage determination circuit determines that the positive input voltage is equal to or lower than the first predetermined voltage, the first control circuit turns off the first switch and outputs the second and second switches. By turning on the third switch, the positive voltage from the first charge pump is supplied to the memory cell array via the third switch. When the second input voltage determination circuit determines that the negative input voltage is lower than the second predetermined voltage, the second control circuit turns on the fourth switch and causes the fifth and sixth switches to turn on.
- the negative input voltage is supplied to the memory cell array via the fourth switch.
- the second control circuit turns off the fourth switch and causes the fifth and sixth switches to turn off.
- the negative voltage from the second charge pump is supplied to the memory cell array via the sixth switch. Therefore, when a positive voltage and a negative voltage are supplied to the memory cell array, a semiconductor memory device capable of supplying a sufficient current to the memory cell array and preventing a circuit malfunction is realized. Can appear.
- a semiconductor memory device is the semiconductor memory device according to any one of the first to third aspects, wherein at least a part of the memory function body of the memory element is a part of the diffusion region. Part overlaps.
- a semiconductor storage device is the semiconductor storage device according to any one of the first to third aspects, wherein a surface substantially parallel to a surface of the gut insulating film of the memory element is provided.
- An insulating film which separates the channel region or the semiconductor layer from a film having a function of retaining electric charges and having a thickness smaller than the thickness of the gate insulating film and not less than 0.8 nm;
- the voltage of the write operation and the erase operation of the memory element is reduced, so that the film of the gate insulating film can cope with a high voltage as in the prior art. There is no need to increase the thickness. Therefore, a short channel effect in the memory element and a transistor included in a circuit for operating the memory element is reduced. As a result, the channel length of the memory element and the transistor forming the circuit for operating the memory element can be shorter than in the related art.
- the area of the capacitor included in the charge pump device can be reduced.
- the portable electronic device according to the eighth invention is the portable electronic device according to any one of the first to third inventions.
- It is characterized by having one semiconductor memory device.
- FIG. 1 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a first embodiment of the present invention.
- FIGS. 2A and 2B are schematic cross-sectional views of main parts of a modified example of the memory element in the semiconductor memory device of the first embodiment.
- FIG. 3 is a diagram for explaining a write operation of a memory element in the semiconductor memory device of the first embodiment.
- FIG. 4 is a diagram for explaining the write operation of the memory element in the semiconductor memory device of the first embodiment.
- FIG. 5 is a diagram for explaining the erasing operation of the memory element in the semiconductor memory device of the first embodiment.
- FIG. 6 is a diagram for explaining an erasing operation of the memory element in the semiconductor memory device of the first embodiment.
- FIG. 7 is a diagram for explaining a read operation of the memory element in the semiconductor memory device of the first embodiment.
- FIG. 8 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a second embodiment of the present invention.
- FIG. 9 is an enlarged schematic sectional view of a main part of the semiconductor memory device of the second embodiment.
- FIG. 10 is an enlarged schematic sectional view of a main part of a modification of the semiconductor memory device of the second embodiment.
- FIG. 11 is a graph showing electric characteristics of a memory element in the semiconductor memory device of the second embodiment.
- FIG. 12 is a schematic sectional view of a main part of a modification of the memory element in the semiconductor memory device of the second embodiment.
- FIG. 13 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a third embodiment of the present invention.
- FIG. 14 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a fourth embodiment of the present invention.
- FIG. 15 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a fifth embodiment of the present invention.
- FIG. 16 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a sixth embodiment of the present invention.
- FIG. 17 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to a seventh embodiment of the present invention.
- FIG. 18 is a schematic sectional view of a main part of a memory element in a semiconductor memory device according to an eighth embodiment of the present invention.
- FIG. 19 is a graph showing the electrical characteristics of the memory element in the semiconductor memory device according to the ninth embodiment of the present invention.
- FIG. 20 is a block diagram of the semiconductor memory device according to the tenth embodiment of the present invention.
- FIG. 21 is a circuit diagram of first, second, and third switches used in the semiconductor memory device.
- FIG. 22 is a circuit diagram of a charge pump used in the semiconductor memory device.
- FIG. 23 is a circuit diagram of a voltage polarity inversion circuit used in the semiconductor memory device.
- FIG. 24 is a flowchart for explaining the operation of the control circuit of the semiconductor memory device.
- FIG. 25 is a block diagram of the semiconductor memory device according to the eleventh embodiment of the present invention.
- FIG. 26 is a schematic configuration diagram of a liquid crystal display device incorporating the semiconductor memory device of the 12th embodiment of the present invention.
- FIG. 27 is a block diagram of a mobile phone as an example of the mobile electronic device according to the thirteenth embodiment of the present invention.
- FIG. 28 is a schematic sectional view of a main part of a conventional flash memory.
- FIG. 29 is a graph showing the electrical characteristics of a conventional flash memory. BEST MODE FOR CARRYING OUT THE INVENTION
- the memory element mainly includes a semiconductor layer, a gate insulating film, a gate electrode, a channel region, a diffusion region, and a memory function body.
- the channel W page area is usually a region of the same conductivity type as the semiconductor layer, and immediately below the gate electrode.
- the diffusion region means a region of the opposite conductivity type to the channel region.
- the memory element of the present invention is configured such that one first conductivity type region that is a diffusion region, a second conductivity type region that is a channel region, and a boundary between the first and second conductivity types are It may be composed of one memory function body arranged over and an electrode provided with a gate insulating film interposed therebetween, but the gate electrode formed on the gate insulating film and both sides of the gate electrode It is appropriate to comprise two formed memory function bodies, two diffusion regions arranged on the opposite side of the memory function body from the Gout electrode, and a channel region arranged under the Gout electrode. is there.
- the semiconductor device of the present invention is preferably formed as a semiconductor layer on a semiconductor substrate, preferably on a first conductivity type well region formed in the semiconductor substrate.
- the semiconductor substrate is not particularly limited as long as it is used for a semiconductor device.
- elemental semiconductors such as silicon and germanium, silicon germanium, GaAs, InGaAs, Zn
- a bulk substrate made of a compound semiconductor such as Se, GaN or the like can be given.
- a semiconductor layer having a semiconductor layer on the surface an SOI (Silicon on Insulator) substrate, a SOS (Silicon on Sapphire) substrate or a multilayer S
- Various substrates such as an OI substrate, or a substrate having a semiconductor layer on a glass or plastic substrate may be used.
- a silicon substrate or an SOI substrate having a silicon layer formed on the surface is preferable.
- the semiconductor substrate or the semiconductor layer may have a small amount of current flowing therein, but may be a single crystal (for example, by epitaxial growth), a polycrystal, or an amorphous.
- An element isolation region is preferably formed on this semiconductor layer, and elements such as a transistor, a capacitor, and a resistor, a circuit including these elements, a semiconductor device, and an interlayer insulating film are combined to form a single or multi-layer structure. It may be formed by.
- the element isolation region can be formed by various element isolation films such as a LOCOS (Local Oxidation of Silicon) film, a trench oxide film, and a STI (Shallow Trench Isolation) film.
- the semiconductor layer may have a P-type or N-type conductivity type, and the semiconductor layer has at least one first conductivity type (P-type or N-type) conductive region formed therein. But preferred.
- the impurity concentration in the semiconductor layer and the wafer region those known in the art can be used.
- the SOI-based In the case of using a plate the surface semiconductor layer may have a weno region, but may have a body region under a channel.
- the gate insulating film is not particularly limited as long as it is usually used for a semiconductor device.
- an insulating film such as a silicon oxide film or a silicon nitride film; an aluminum oxide film, a titanium oxide film, or an acid oxide film.
- a single-layer film or a laminated film of a high dielectric constant film such as a film or a hafnium oxide film can be used.
- a silicon oxide film is preferable.
- the thickness of the gate insulating film is, for example, about l to 20 nm, preferably about l to 6 nm.
- the gate insulating film may be formed only immediately below the gate electrode, or may be formed larger (wider) than the gate electrode.
- the gate electrode is formed on the gate insulating film in a shape usually used for a semiconductor device or a shape having a concave portion at a lower end.
- the gate electrode is preferably formed as an integral shape without being separated by a single-layer or multilayer conductive film; however, the gate electrode may be separated and formed by a single-layer or multilayer conductive film. Good. Further, the gate electrode may have a sidewall insulating film on a sidewall.
- the gate electrode is not particularly limited as long as it is generally used for a semiconductor device.
- a conductive film for example, a metal such as polysilicon: copper and aluminum: a high melting point metal such as tungsten, titanium, and tantalum : A single-layer film such as a silicide with a high melting point metal or a laminated film.
- the gate electrode is preferably formed to a thickness of, for example, about 50 to 400 nm. Note that a channel region is formed below the gate electrode.
- the gate electrode is formed only on the side wall of the memory function body described later, or does not cover the upper part of the memory function body.
- the contact plug can be arranged closer to the gut electrode, so that miniaturization of the memory element is facilitated.
- a memory element having such a simple arrangement is easy to manufacture and can improve the yield.
- the memory functional unit has at least a function of retaining charges (hereinafter referred to as a “charge retaining function”). In other words, it has the ability to store and retain charge ⁇ the ability to trap charge, and the function to maintain the charge polarization state.
- This function has, for example, a charge retention function. This is exhibited by the fact that the memory function body includes a film or region to be formed.
- Materials that fulfill this function include: silicon nitride; silicon; silicate glass containing impurities such as phosphorus and boron; silicon carbide; alumina; high dielectric materials such as hafnium oxide, zirconium oxide, and tantalum oxide; Subguchi; ferroelectric; metal.
- the memory function body includes, for example, an insulating film containing a silicon nitride film; an insulating film containing a conductive film or a semiconductor layer inside; an insulating film containing one or more conductive materials or semiconductor dots; It can be formed by a single-layer or laminated structure of an insulating film or the like including a ferroelectric film in which the state is maintained.
- the silicon nitride film has a large number of levels for trapping electric charges, so it can obtain large hysteresis characteristics.
- the charge retention time is long, and there is no problem of charge leakage due to the occurrence of leak paths. Good properties,
- an insulating film including a film having a charge retention function such as a silicon nitride film as a memory function body, reliability of storage retention can be improved. This is because, since the silicon nitride film is an insulator, even if a charge leaks in a part of the silicon nitride film, the charge in the entire silicon nitride film is not immediately lost. Also, when a plurality of memory elements are arranged, even if the distance between the memory elements is shortened and the adjacent memory functions come into contact with each other, each memory function body is made of a conductor as in the case where the memory functions are made of a conductor. The information stored in the memory is not lost. Further, the contact plug can be arranged closer to the memory function body, and in some cases, can be arranged so as to overlap with the memory function body, which facilitates miniaturization of the memory element.
- a charge retention function such as a silicon nitride film
- the film having the charge holding function does not necessarily have to be in the form of a film in order to increase the reliability of the memory holding, and it is preferable that the film having the charge holding function be discretely present in the insulating film. Specifically, it is preferable that a material having a charge retention function is dispersed in a dot-like material in a material that does not easily retain charge, for example, silicon oxide.
- the charge holding film should not be in direct contact with the semiconductor layer (semiconductor substrate, cell region, body region or source / drain region or diffusion region) or the gate electrode. It is possible to place it via an insulating film. Is preferred. For example, a laminated structure of a conductive film and an insulating film, a structure in which a conductive film is dispersed in a dot shape or the like in an insulating film, a structure in which the conductive film is disposed in a part of a sidewall insulating film formed on a sidewall of a gut, and the like are given. Can be
- an insulating film including a conductive film or a semiconductor layer therein as the memory function body, since the amount of electric charge injected into the conductor or the semiconductor can be freely controlled and multivalued can be easily performed.
- an insulating film including one or more conductors or semiconductor dots as a memory function body, writing and erasing by direct tunneling of charges can be easily performed, and power consumption can be reduced, which is preferable.
- a ferroelectric film such as PZT (zirconium titanate ⁇
- polarization generates a substantial electric charge on the surface of the ferroelectric film, and the electric charge is maintained in that state. Therefore, electric charge is supplied from the outside of the film having the memory function, and the same hysteresis characteristic as that of the film that traps the electric charge can be obtained. This is preferable because the hysteresis characteristic can be obtained only by the polarization of the charge in the film without the necessity of writing and erasing at high speed.
- the insulating film constituting the memory function body is a region that makes it difficult for electric charge to escape or a film that has a function to make it difficult for electric charge to escape. Is a silicon oxide film.
- the charge retention films included in the memory functional unit are arranged directly or on both sides of the gut electrode via an insulating film, and the semiconductor layers (semiconductor substrate, gel region, body region, or (Source / drain region or diffusion region). It is preferable that the charge holding films on both sides of the gate electrode are formed so as to cover all or a part of the side wall of the gate electrode directly or via an insulating film. As an application example, when the gate electrode has a concave portion at the lower end portion, the concave portion may be formed completely or partially so as to bury the concave portion directly or via an insulating film.
- the diffusion region can function as a source / drain region and has a conductivity type opposite to that of the semiconductor layer or the anodic region. Junction between diffusion region and semiconductor layer or layer Preferably, the impurity concentration is steep. This is because hot electrons and hot holes are generated efficiently at low voltage, and high-speed operation at lower voltage is possible.
- the junction depth of the diffusion region is not particularly limited, and can be appropriately adjusted according to the performance of the semiconductor memory device to be obtained. Note that when an SOI substrate is used as the semiconductor substrate, the diffusion region may have a junction depth smaller than the thickness of the surface semiconductor layer, but the junction depth is approximately the same as the thickness of the surface semiconductor layer. It preferably has a depth.
- the diffusion region may be arranged so as to overlap with the gate electrode end, may be arranged so as to coincide with the good electrode end, or may be arranged offset from the good electrode end.
- the offset amount that is, the gate amount, is smaller than the thickness of the charge retention film in the direction parallel to the gut length direction.
- the distance from one end of the gut electrode in the long direction to the closer diffusion region is shorter. It is particularly important that at least a part of the film or the region having the charge retention function in the memory function body overlaps with a part of the diffusion region.
- the essence of the memory element constituting the semiconductor memory device of the present invention is that the memory is rewritten by an electric field across the memory function body due to the voltage difference between the gate electrode and the diffusion region existing only on the side wall of the memory function body. It is.
- the diffusion region may partially extend to a position higher than the surface of the channel region, that is, the lower surface of the gate insulating film. In this case, it is appropriate that a conductive film integrated with the diffusion region is laminated on the diffusion region formed in the semiconductor substrate.
- the conductive film examples include semiconductors such as polysilicon and amorphous silicon, silicide, the above-mentioned metals, and high-melting point metals.
- semiconductors such as polysilicon and amorphous silicon, silicide, the above-mentioned metals, and high-melting point metals.
- polysilicon is preferable. This is because polysilicon has an extremely high impurity diffusion rate as compared with the semiconductor layer, so it is easy to reduce the junction depth of the diffusion region in the semiconductor layer, and the short channel effect is suppressed. In this case, It is preferable that a part of the diffusion region is disposed so as to sandwich at least a part of the memory function body together with the gate electrode.
- the memory element of the present invention can be formed by an ordinary semiconductor process, for example, by a method similar to the method of forming a single-layer or stacked-layer sidewall spacer on the side wall of a gate electrode.
- a film having a charge holding function hereinafter referred to as “charge holding film”
- charge holding film Z insulating film a film having a charge holding function
- insulating film Z insulating film an insulating film / charge holding film
- an insulating film / charge holding film Z A method of forming a single-layer film or a laminated film including a charge retaining film such as an insulating film, etching back under appropriate conditions and leaving these films in a side-warner spacer shape; Method of forming, etching back under appropriate conditions and leaving it in a sidewall spacer shape, further forming a charge retention film or insulating film, and similarly etching back to leave a sidewall spacer shape; particles
- a method of forming the single-layer film or the laminated film, and patterning using a mask may be used. Also, before forming the gate electrode, a charge holding film, a charge holding film Z insulating film, an insulating film Z charge holding film, an insulating film Z charge holding film, an insulating film, etc. are formed, and a channel region of these films is formed. An opening is formed in the region, a gate electrode material film is formed over the entire surface, and the gate electrode material film is patterned into a shape including the opening and larger than the opening. An example of a method for forming the memory element will be described.
- a gate insulating film and a gate electrode are formed on a semiconductor substrate by a known procedure. Subsequently, a silicon oxide film having a thickness of 0.8 to 20 nm, more preferably 3 to 10 nm is formed on the entire surface of the semiconductor substrate by a thermal oxidation method.
- a silicon oxide film of 20 to 70 nm is deposited on the entire surface of the silicon nitride film by a CVD method.
- the optimal memory function body A sidewall spacer is formed on the side wall of the contact electrode.
- a diffusion layer region (source / drain region) is formed by ion-implanting the gate electrode and the sidewall spacer-shaped memory function body as a mask.
- the silicide process and the upper wiring process may be performed by a known procedure.
- the gut electrodes of a plurality of memory elements have a function of a lead wire integrally
- a memory function body is formed on both sides of the above-mentioned lead line
- the memory function body is composed of an ONO (Oxide Nitride Oxide) film, and the silicon nitride has a surface substantially parallel to the surface of the gate insulating film.
- ONO Oxide Nitride Oxide
- the silicon nitride film in the memory function body is separated from the lead line and channel region by a silicon oxide film.
- the thickness of the insulating film separating the silicon nitride film having a surface substantially parallel to the surface of the gate insulating film from the channel region or the semiconductor layer is different from the thickness of the gate insulating film.
- Writing and erasing operations of one memory element are performed by a single lead line.
- Particularly preferred combinations of the above requirements include, for example, (3) an insulator, particularly a silicon nitride film, that retains electric charge in the memory function body, and (6) a diffusion with the insulating film (silicon nitride film) in the memory function body. (9) An electrode (pad) having a function to assist writing and erasing operations is placed on the memory function body. Line).
- the bit line contact can be arranged closer to the memory function body on the word line side wall, or even if the distance between the memory elements is short, the plurality of memory function bodies do not interfere, and the stored information can be stored. Can be retained. Therefore, miniaturization of the memory element is facilitated.
- the charge holding region in the memory function body is a conductor, interference occurs between the charge holding regions as the memory elements approach each other due to capacitive coupling, and storage information cannot be held.
- the charge holding region in the memory function body is an insulator (for example, a silicon nitride film), it is not necessary to make the memory function body independent for each memory cell.
- the memory function bodies formed on both sides of one memory cell shared by multiple memory cells do not need to be separated for each memory cell, and the memory functions formed on both sides of one memory cell line do not need to be separated.
- the body can be shared by a plurality of memory cells sharing a lead line. Therefore, a photo and etching process for separating the memory function body is not required, and the manufacturing process is simplified. Furthermore, since the margin for alignment margin and etching is not required as much as the photolithographic process, the margin between memory cells can be reduced.
- the area occupied by the memory cell can be reduced even when formed at the same fine processing level. If the charge holding area in the memory function body is a conductor, a photo and etching process is required to separate the memory function body for each memory cell, and a photo alignment margin and a film reduction margin for etching are required. Required.
- the charge holding area and the diffusion area in the memory function By overlapping the area, writing and erasing can be performed at a very low voltage. Specifically, writing and erasing operations can be performed with a low voltage of 5 V or less. This is a very significant effect on circuit design. Since it is not necessary to produce a high voltage in a chip as in a flash memory, it is possible to omit or reduce the size of a charge pumping circuit which requires a huge occupied area.
- the area occupied by the memory section is dominated by the peripheral circuit that drives the memory cell rather than the memory cell. Omitting or reducing the scale of the voltage boosting circuit for use is most effective for reducing the chip size.
- the requirement (3) is not satisfied, that is, when the electric charge is held in the memory function body
- the requirement (6) is not satisfied, that is, the conductor and the diffusion region in the memory function body are not satisfied.
- the write operation can be performed even when the bits do not overlap. This is because the conductor in the memory function assists writing by capacitive coupling with the gate electrode.
- the requirement (9) is not satisfied, that is, when there is an electrode having a function of assisting the writing and erasing operations on the memory function body, the requirement (6) is not satisfied.
- the writing operation can be performed even when the body and the diffusion region do not overlap.
- one or both of the memory elements may have a transistor connected in series, or may be mounted on the same chip as the logic transistor.
- a memory element can be formed in a process that is very compatible with the process of forming a normal standard transistor such as a transistor and a logic transistor. Can be formed. Therefore, the process of mounting a memory element and a transistor or a logic transistor is very simple, and an inexpensive hybrid device can be obtained.
- the memory element can store binary or more information in one memory function body, thereby functioning as a memory element for storing quaternary or more information. Can be done.
- the memory element is binary May simply be stored.
- the memory element can also function as a memory cell having both functions of a selection transistor and a memory transistor due to the variable resistance effect of the memory function body.
- the semiconductor memory device of the present invention can be used in combination with a logic element or a logic circuit to provide a personal computer, a notebook, a laptop, a personal assistant transmitter, a minicomputer, a workstation, a mainframe, a multiprocessor computer, Data processing systems such as computer systems of all other types; electronic components that make up data processing systems such as CPUs, memories, and data storage devices; telephones, PHS (Personal Handiphone System), Communication equipment such as modems and routers; Image display equipment such as display panels and projectors; Office equipment such as printers, scanners, and copiers; Imaging equipment such as video cameras and digital cameras; Entertainment equipment such as game machines and music players ; Mobile information Information devices such as clocks, electronic dictionaries, etc .; on-board devices such as car navigation systems and car audio; AV (Audio Visiial) devices for recording and playing back information such as videos, still images, and music; washing machines, electronic devices Electric appliances such as microwave ovens, refrigerators, rice cookers, dishwashers, vacuum cleaner
- the semiconductor memory device of the present invention may be built in as at least a part of a control circuit or a data storage circuit of an electronic device, or may be detachably incorporated as necessary.
- the semiconductor memory device of this embodiment includes a memory element 1001 as an example of a nonvolatile memory element as shown in FIG.
- the memory element 1001 is formed by a ⁇ ⁇ -shaped area formed on the surface of the semiconductor substrate 1101.
- a gate electrode 1104 is formed on 1102 with a gate insulating film 1103 interposed therebetween.
- a silicon nitride film 1109 having a trap level for retaining charges and serving as a charge retention film is disposed.
- the side wall portions of 104 are memory functional bodies 1 105 a and 1 105 b, respectively, which actually hold electric charges.
- the memory functional body refers to a portion of the memory functional body or the charge holding film in which charges are actually accumulated by the rewriting operation.
- N-type diffusion regions 1107a and 1107b each functioning as a source region or a drain region are formed.
- the diffusion regions 1107a and 1107b have an offset structure. That is, the diffusion regions 1107a and 1107b do not reach the region 111 under the gate electrode, and the offset region 1120 under the charge retaining film (silicon nitride film 109) It forms part of the channel area.
- the memory functional bodies 1105a and 1105b that substantially hold electric charges are both side wall portions of the gate electrode 1104. Therefore, it is sufficient that the silicon nitride film 1109 is formed only in the region corresponding to this portion (see FIG. 2A). Further, the memory functional bodies 1105a and 1105b have a structure in which fine particles 1 1 and 2 made of a nanometer-sized conductor or semiconductor are distributed in the insulating film 1 1 1 1 in a scattered manner. (See Figure 2B). At this time, if the fine particles 1 1 1 2 are less than 1 nm, the quantum effect is too large and it is difficult for charges to tunnel through the dots, and if it exceeds 10 nm, no significant quantum effect appears at room temperature. . Therefore, particle 1
- the diameter of 112 is in the range of 1 nm to 10 nm.
- the silicon nitride film 109 serving as the charge retention film may be formed in a side wall spacer shape on the side surface of the good electrode (see FIG. 3).
- writing refers to injecting electrons into the memory functional bodies 113a and 113b when the memory element is an N-channel type.
- the description will be made assuming that the memory element is of the N channel type.
- the N-type first diffusion region 1107a is used as a source electrode
- the N-type second diffusion region 1107b is used as a drain electrode.
- 0 V is applied to the first diffusion region 1107a and P-type p-type region 1102
- +5 V is applied to the second diffusion region 1107b
- 0V is applied to the gate electrode 1104.
- +5 V is applied to the inversion layer 1 2 26 force extends from the first diffusion region 1 107 a (source electrode), but the second diffusion region
- a pinch-off point occurs without reaching 1 107 b (drain electrode).
- the electrons are accelerated by a high electric field from the pinch-off point to the second diffusion region 1107b (drain electrode) and become so-called hot electrons (high-energy conduction electrons).
- the writing is performed by injecting the hot electrons into the second memory function body 113 b. Note that no writing is performed in the vicinity of the first memory function body 1131a because hot electrons do not occur.
- the second diffusion region 110 7 b is used as a source electrode, and the first The diffusion region 1107a of this is used as a drain electrode.
- the first The diffusion region 1107a of this is used as a drain electrode.
- 0 V for the second diffusion region 1107 b and P-type p-type region 1102, +5 V for the first diffusion region 1107a, and +5 V for the gate electrode 1104 Is applied.
- the case where electrons are injected into the second memory function body 113 1 b is different from the case where electrons are injected into the first memory function body 113 1 a by exchanging the source / drain regions. Can be written.
- a positive voltage for example, +5 V
- 0 V is applied to the P-type well region 1102
- a reverse bias is applied to the PN junction between the first diffusion region 1107a and the P-type well W shell region 1102.
- a negative voltage eg, 15 V
- the potential gradient is particularly steep due to the influence of the gate electrode to which the negative voltage is applied. Therefore, hot holes (high-energy holes) are generated on the P-type well region 1102 side of the PN junction by the band-to-band tunnel.
- This hot hole is drawn in the direction of the gate electrode 1104 having a negative potential, and as a result, holes are injected into the first memory function body 113a. In this way, One memory function body 1 1 3 1a is erased. At this time, 0 V may be applied to the second diffusion region 110 b.
- the potentials of the first diffusion region and the second diffusion region may be exchanged as described above.
- a positive voltage for example, +4 V
- 0 V on the second diffusion region 110 b a negative voltage (for example, 14 V) on the gate electrode 110
- a positive voltage for example, +0 8 V
- a forward voltage is applied between the P-type pole region 1102 and the second diffusion region 1107b, and electrons are injected into the P-type Ueno ⁇ I region 1102. Is done.
- the injected electrons diffuse to the PN junction between the P-type well region 1102 and the first diffusion region 1107a, where they are accelerated by a strong electric field to become hot electrons.
- This hot electron generates an electron-hole pair at the PN junction. That is, by applying a forward voltage between the P-type well region 1102 and the second diffusion region 1107b, the P-type well 1_B region 1102 was implanted. Electrons trigger and generate hot holes at the opposite PN junction. Hot holes generated at the PN junction are drawn toward the gate electrode 1104 having a negative potential, and as a result, holes are injected into the first memory function body 113a.
- the second pn junction between the p-type Ueno region and the first diffusion region 1107a can be used even when only a voltage that is insufficient to generate hot holes due to the interband tunnel is applied. Electrons injected from the diffusion region 1107b serve as triggers for generating electron-hole pairs at the PN junction, and can generate hot holes. Therefore, the voltage during the erasing operation can be reduced. In particular, when the offset region 1120 (see Fig. 1) exists, the effect that the PN junction becomes sharp due to the gate electrode to which the negative potential is applied is small. For this reason, it is difficult to generate hot holes due to the band-to-band tunneling. However, the second method can compensate for the drawback and realize the erasing operation at a low voltage.
- +5 V When erasing information stored in the first memory function body 1 1 3 1 a, in the first erasing method, +5 V must be applied to the first diffusion region 1 107 a. Inside However, +4 V was sufficient for the second erase method. As described above, according to the second method, the voltage at the time of erasing can be reduced, so that the power consumption is reduced and the deterioration of the memory element due to the hot carrier can be suppressed.
- over-erasure of the memory element is difficult with either erasing method.
- over-erasing is a phenomenon in which the threshold value decreases without saturation as the amount of holes accumulated in the memory function body increases.
- EEPROM electrically erasable and writable read-only memory
- flash memory electrically erasable and writable read-only memory
- the threshold value becomes negative, making it impossible to select memory cells. Operation failure occurs.
- the memory element of the semiconductor memory device of the present invention even when a large amount of holes are accumulated in the memory function body, electrons are only induced under the memory function body, and the channel region under the gut insulating film is not affected. Has little effect on the potential of Since the threshold at the time of erasing is determined by the potential under the gate insulating film, over-erasing is less likely to occur.
- the first diffusion region 1 107 a is used as a source electrode
- the second diffusion region 1 107 b is used as a drain electrode
- Activate the transistor For example, 0 V is applied to the first diffusion region 1107a and the P-type p-type region 1102, +1.8 V is applied to the second diffusion region 1107b, and + V is applied to the gate electrode 1104. Apply 2 V. At this time, if no electrons are accumulated in the first memory function body 113a, a drain current is likely to flow.
- the second diffusion region 1 107 b When reading the information stored in the second memory function body 1 1 3 1 b, the second diffusion region 1 107 b is used as a source electrode, the first diffusion region 1 107 a is used as a drain electrode, Activate the transistor.
- the first diffusion region 1 107 a is used as a drain electrode, Activate the transistor.
- +1.8 V is applied to the first diffusion region 1107a
- +2 V is applied to the gate electrode 1104, Good.
- the case where the information stored in the first memory function body 1131a is read is the same as the case of reading the information stored in the second memory function body 1131b by replacing the source Z drain region. Reading can be performed.
- offset region 1120 when a channel region (offset region 1120) not covered by the gate electrode 1104 is left, an excess of the memory function bodies 1131a and 1131b is left in the channel region not covered by the gate electrode 1104. Depending on the presence or absence of charge, the inversion layer disappears or forms, resulting in a large hysteresis (change in threshold). However, if the width of the offset region 1120 is too large, the drain current is greatly reduced, and the reading speed is significantly reduced. Therefore, it is preferable to determine the width of the offset region 1120 so that sufficient hysteresis and reading speed can be obtained.
- the diffusion regions 1107a and 1107b reach the end of the gate electrode 1104, that is, when the diffusion regions 1107a and 1107b overlap with the gate electrode 1104.
- the threshold of the transistor did not change much due to the write operation, the parasitic resistance at the source / drain ends changed significantly, and the drain current decreased significantly (by one digit or more). Therefore, reading can be performed by detecting the drain current, and a function as a memory can be obtained.
- the diffusion regions 1107a and 1107b do not overlap with the gate electrode 1104 (the offset region 1120 exists).
- the word line WL is connected to the gate electrode 1104 of the memory element
- the first bit line BL 1 is connected to the first diffusion region 1107a
- the second bit line BL 2 is connected to the second diffusion region 1107b.
- the source electrode and the drain electrode are exchanged. Therefore, two bits of writing and erasing are performed per transistor, but the source electrode and the drain electrode may be fixed and operated as a one-bit memory. In this case, one of the source / drain regions can be set to a common fixed voltage, and the number of bit lines connected to the source / drain regions can be reduced by half.
- the memory function body is formed independently of the gate insulating film and formed on both sides of the gate electrode, so that the two-bit operation can be performed. It is possible. Further, since each memory function body is separated by the gate electrode, interference at the time of rewriting is effectively suppressed. Further, since the gate insulating film is separated from the memory function body, the gate insulating film can be thinned to suppress the short channel effect. Therefore, miniaturization of the memory element, and eventually the semiconductor memory device, is facilitated.
- drawings are schematic, and the relationship between thickness and plane dimensions, the ratio of the thickness and size of each layer and each part, and the like are different from actual ones. Therefore, specific dimensions of thickness and size should be determined in consideration of the following explanation. It goes without saying that the drawings also include portions having different dimensional relationships and ratios.
- each layer and each portion described in this patent are dimensions of a final shape at the stage when the formation of the semiconductor device is completed. Therefore, it should be noted that the size of the final shape is slightly changed due to the heat history of the subsequent process as compared with the size immediately after the formation of the film or the impurity region.
- the memory element in the semiconductor memory device of this embodiment has a region in which the memory functional bodies 1261 and 1262 hold charge (a region that stores charge and holds charge).
- the memory shown in FIG. 1 except that the memory shown in FIG. 1 is composed of a film having a function to make the charge escape, and a region which makes it difficult for the charge to escape (the film may have a function to make the charge difficult to escape). It has a configuration substantially similar to that of the element 1001.
- the memory functional unit is a device that retains electric charge from the viewpoint of improving the retention characteristics of memory. It is preferable to include a charge holding film having a function and an insulating film.
- a silicon nitride film 1242 having a level for trapping charges is used as a charge holding film, and silicon oxide films 1241 and 1243 having a function of preventing dissipation of charges accumulated in the charge holding film are used as an insulating film. ing. Since the memory function body includes the charge holding film and the insulating film, the dissipation of charges can be prevented and the holding characteristics can be improved. In addition, the volume of the charge retaining film can be reduced appropriately compared to the case where the memory function body is formed only of the charge retaining film.
- the silicon nitride film 1242 may be replaced with a ferroelectric.
- the regions (silicon nitride film 1242) for retaining charges in the memory functional bodies 1261 and 1262 overlap with the diffusion regions 1212 and 1213, respectively.
- overlap means that at least a part of the charge retaining region (silicon nitride film 1242) exists on at least a part of the diffusion regions 1212 and 1213.
- 121 1 is a semiconductor substrate
- 121 4 is a gate insulating film
- 1271 is an offset region between the gate electrode 1217 and the diffusion regions 1212 and 1213.
- the outermost surface of the semiconductor substrate 1211 under the gate insulating film 1214 is a channel region.
- the offset amount between the gate electrode 1217 and the diffusion region 1213 in the peripheral portion of the memory function body 1262 is represented by W1
- the width of the memory function body 1262 in the section of the gate electrode 1217 in the channel length direction is defined.
- W 2 be the amount of overlap between the memory function body 1262 and the diffusion area 1213 is represented by W 2 ⁇ W 1.
- the memory function body 1262 of the memory function body 1262 which is composed of the silicon nitride film 1242, overlaps with the diffusion region 1213. That is, it satisfies the relationship of W 2> W1.
- the end of the silicon nitride film 1242 of the memory function body 1262 that is remote from the gate electrode 1217 matches the end of the memory function body 1262 that is remote from the gate electrode 1217.
- the width of the memory function body 1262 is defined as W2.
- the end of the memory function body 1262a on the side of the silicon nitride film 1242a remote from the gate electrode 1217a is connected to the memory function body 1262a on the side remote from the gate electrode 1217a. If it does not coincide with the end of the gate electrode, W 2 may be defined as from the end of the gate electrode to the end of the silicon nitride film 1242 a on the far side from the gut electrode 1217 a.
- FIG. 11 shows the drain current I d when the width W2 of the memory function body 1262 is fixed to 100 nm and the offset amount W1 is changed in the structure of the memory element in FIG.
- the drain current was obtained by device simulation using the memory function body 1262 in an erased state (having holes) and the diffusion regions 1212 and 1213 as a source electrode and a drain electrode, respectively.
- W1 is 100 nm or more (that is, the silicon nitride film 1242 and the diffusion region 1213 do not overlap)
- the drain current decreases rapidly. Since the drain current is almost proportional to the read operation speed, the memory performance is rapidly deteriorated when W1 is 100 nm or more.
- the drain current decreases slowly. Therefore, in consideration of variation in mass production, if at least part of the silicon nitride film 1242, which is a film having a function of retaining electric charges, does not overlap with the source / drain region, a memory function can be obtained effectively. Have difficulty.
- a memory cell array was fabricated with W2 fixed at 100 nm and W1 set at 60 nm and 100 nm as design values.
- W1 is 60 nm
- the silicon nitride film 142 and the diffusion regions 1212 and 1213 overlap by 40 nm as a design value
- W1 force S is 100 nm
- the read access time was 100 times faster when W1 was set to 60 nm as the design value, compared with the worst case considering the variation.
- the read access time is preferably less than 100 nanoseconds per bit, but this condition cannot be achieved with W 1 -W 2 at all.
- the information stored in the memory function unit 1261 (area 12881) is read by using the diffusion area 1212 as the source electrode and the diffusion area 1213 as the same as in the first embodiment. It is preferable to form a pinch-off point on the side near the drain region in the channel region as the rain region. That is, when reading information stored in one of the two memory function bodies, it is preferable to form the pinch-off point in a region within the channel region and close to the other memory function body. This makes it possible to detect the stored information of the memory functional unit 1261 with high sensitivity regardless of the storage state of the memory functional unit 1262, which is a major factor that enables 2-bit operation. Become.
- a well region (a P-type well in the case of an N-channel element) on the surface of the semiconductor substrate 121.
- a well region a P-type well in the case of an N-channel element
- the memory function body includes a charge retention film disposed substantially parallel to the surface of the gate insulating film.
- the upper surface of the charge retaining film in the memory function body is disposed at an equal distance from the upper surface of the gate insulating film.
- the silicon nitride film 124 2 a which is the charge retaining film of the memory functional unit 126 2, and the surface substantially parallel to the surface of the gut insulating film 1 214 are Have.
- the silicon nitride film 1242a is preferably formed to have a uniform height from the height corresponding to the surface of the gate insulating film 124.
- the silicon nitride film almost parallel to the surface of the gut insulating film 1 2 1 4
- the presence of the oxide film 1242a effectively controls the easiness of the formation of the inversion layer in the offset region 1271, depending on the amount of charge accumulated in the silicon nitride film 1242a. And thus the memory effect can be increased.
- the silicon nitride film 1242a substantially parallel to the surface of the gate insulating film 124, the change in the memory effect is kept relatively small even when the offset amount (W1) varies. Therefore, variations in the memory effect can be suppressed.
- the movement of charges in the upper direction of the silicon nitride film 12442a is suppressed, and the occurrence of a change in characteristics due to the movement of charges during storage can be suppressed.
- the memory function body 1 262 is formed of an insulating film (for example, a silicon nitride film 124) substantially parallel to the surface of the gut insulating film 124 and the channel region (or a p-well region). It is preferable to include the silicon oxide film 124 4 on the offset region 1271. With this insulating film, dissipation of the charge accumulated in the charge holding film is suppressed, and a memory element with better holding characteristics can be obtained.
- an insulating film for example, a silicon nitride film 124 substantially parallel to the surface of the gut insulating film 124 and the channel region (or a p-well region). It is preferable to include the silicon oxide film 124 4 on the offset region 1271. With this insulating film, dissipation of the charge accumulated in the charge holding film is suppressed, and a memory element with better holding characteristics can be obtained.
- the insulating film under the silicon nitride film 1242a (the portion of the silicon oxide II
- the film thickness is calculated based on the minimum thickness of the insulating film below the silicon nitride film 1242a. It can be controlled up to the sum of the maximum thickness value of the lower insulating film and the maximum thickness ⁇ fi of the silicon nitride film 1242a. This makes it possible to generally control the density of lines of electric force generated by the electric charge stored in the silicon nitride film 1242a, and to greatly reduce the variation in the magnitude of the memory effect of the memory element. It becomes.
- the memory function body 1262 in the semiconductor memory device of this embodiment has a gate insulating film 1242 as a charge retention film having a substantially uniform film thickness as shown in FIG. It has a shape that is arranged substantially parallel to the surface of the insulating film 1 2 14 (region 1 2 8 1), and furthermore is arranged substantially parallel to the side surface of the gate electrode 1 2 1 7 (region 1 2 8 2). ing.
- a positive voltage is applied to the gate electrode 1 2 1 7
- the electric lines of force pass through the silicon nitride film 1 242 twice (regions 1 282 and 1 281).
- a negative voltage is applied to the gate electrode 12 17, the direction of the electric flux lines is on the opposite side.
- the relative permittivity of the silicon nitride film 1242 is about 6, and the relative permittivity of the silicon oxide films 1241 and 1243 is about 4. Therefore, the effective specific permittivity of the memory function body 1 262 in the direction of the electric force lines (arrows 1 283) becomes larger than in the case where only the region 1 281 of the charge retention film is present, The potential difference at both ends of the lines of electric force can be further reduced. That is, a large part of the voltage applied to the gate electrode 127 is used to increase the electric field in the offset area 127 1.
- the charge is injected into the silicon nitride film 1242 during the rewrite operation because the generated charge is drawn by the electric field in the offset region 1271. Therefore, when the silicon nitride film 1242 includes the region 1282, the charge injected into the memory functioning body 1262 during the rewriting operation increases, and the rewriting speed increases. If the silicon oxide film 1243 is also a silicon nitride film, that is, if the charge retention film is not uniform with respect to the height corresponding to the surface of the gut insulating film 124, silicon nitride The charge transfer in the upward direction of the film becomes remarkable, and the retention characteristics deteriorate.
- the charge retention film is formed of a high dielectric material such as hafdium oxide having a very large relative dielectric constant instead of the silicon nitride film.
- the memory functional unit is provided with an insulating film (a silicon oxide film 1241, an offset region 1 2 7 1) that separates the charge retaining film substantially parallel to the surface of the gate insulating film from the channel region (or the Wenore region). (Upper part).
- an insulating film a silicon oxide film 1241, an offset region 1 2 7 1 that separates the charge retaining film substantially parallel to the surface of the gate insulating film from the channel region (or the Wenore region). (Upper part).
- the memory function body includes an insulating film (a portion of the silicon oxide film 1241, which is in contact with the gate electrode 1217) that separates the gate electrode from the charge retention film extending in a direction substantially parallel to the side surface of the gate electrode. ) Is preferable.
- This insulating film prevents the charge from being injected from the gate electrode into the charge retaining film and prevents the electrical characteristics from changing, thereby improving the reliability of the memory element.
- the thickness of the insulating film below the silicon nitride film 1242 (the portion of the silicon oxide film 1241 above the offset region 1271) is controlled to be constant.
- the thickness of the insulating film (the portion of the silicon oxide film 1241 in contact with the gate electrode 127) that is disposed on the side surface of the gate electrode.
- A is the gate electrode length in the cross section in the channel length direction
- B is the distance between the source / drain regions (channel length)
- C is the end of one memory function body to the other memory function.
- the offset region 1271 exists between the portion below the gate electrode 1217 in the channel region and the diffusion regions 1122 and 1213. Become.
- the electric charge accumulated in the memory function bodies 1261 and 1262 silicon nitride film 1242 effectively facilitates inversion in the entire offset area 1271. To fluctuate. Therefore, the memory effect increases, and particularly, the speed of the read operation is increased.
- the gate electrode 12 17 and the diffusion regions 12 12 and 12 13 are offset, that is, when A ⁇ B holds, the offset when a voltage is applied to the gate electrode
- the strength of the inversion of the region greatly changes depending on the amount of electric charge stored in the memory function body, so that the memory effect increases and the short channel effect can be reduced.
- the offset region 1 2 71 need not be present. Even when the offset region 1271 does not exist, if the impurity concentration of the diffusion regions 1212 and 1213 is sufficiently low, a memory effect can be exhibited in the memory functional bodies 1261 and 1262 (silicon nitride film 1242).
- the silicon nitride film 1242a and the source / drain regions 1212 and 1213 do not overlap, it is practically difficult to obtain a memory function. It is preferably C. For these reasons, it is most preferable that A ⁇ B and C.
- the memory element of the semiconductor memory device according to this embodiment has a substantially similar configuration except that the semiconductor substrate according to the second embodiment is an SOI substrate.
- a buried oxide film 1288 is formed on a semiconductor substrate 1286, and an SOI layer is further formed thereon. Diffusion regions 1212 and 1213 are formed in the SOI layer, and the other region is a body region 1287.
- This memory element also has the same operation and effect as the memory element of the second embodiment. Further, the junction capacitance between the diffusion regions 1212 and 1213 and the body region 1287 can be significantly reduced, so that the speed of the element can be increased and the power consumption can be reduced.
- the memory element in the semiconductor memory device according to this embodiment has the same structure as that of the first embodiment except that a P-type high-concentration region 1291 is added adjacent to the channel side of the N-type diffusion regions 1212 and 1213. It has a configuration substantially similar to the memory element of the second embodiment.
- the concentration of an impurity (for example, pol- um) giving P-type in the P-type high concentration region 1291 is higher than the impurity concentration giving P-type in the region 1292.
- An appropriate P-type impurity concentration in the P-type high concentration region 1291 is, for example, about 5 ⁇ 10 17 to 1 ⁇ 10 19 cm ⁇ 3 .
- the P-type impurity concentration of the region 1292 can be, for example, 5 ⁇ 10 16 to 1 ⁇ 10 18 cm— 3 .
- the voltage of the writing and erasing operations can be reduced, or the speed of the writing and erasing operations can be increased.
- the impurity concentration of the region 1292 is relatively low, the threshold value when the memory is in the erased state is low, and the drain current is large. Therefore, the reading speed is improved. Therefore, it is possible to obtain a memory element having a low rewrite voltage or a high rewrite speed and a high read speed.
- the provision of the P-type high-concentration region 1291 significantly increases the threshold value of the transistor as a whole.
- the extent of this increase is significantly greater than in the case where the P-type high-concentration region 1291 is immediately below the gate electrode. This difference is even greater if write charge (or electrons if the transistor is an N-channel type) accumulates in the memory function.
- the threshold value of the transistor as a whole is determined by the channel region under the gate electrode (region 1 292) Lower than the threshold value determined by the impurity concentration.
- the threshold value at the time of erasing does not depend on the impurity concentration of the P-type high-concentration region 1291, while the threshold value at the time of writing is greatly affected. Therefore, by arranging the P-type high-concentration region 1 291 below the memory function body and in the vicinity of the source / drain region, only the threshold value ⁇ S at the time of writing greatly fluctuates, and the (The difference between the threshold and the erasure at the time of erasure) can be significantly increased.
- the memory element in the semiconductor memory device of this embodiment includes an insulating film 12 separating the charge holding film (silicon nitride film 124 2) from the channel region or the well region 1 2 1 1 1. Except that the thickness (T 1) of 41 is smaller than the thickness ( ⁇ 2) of the gate insulating film 122, it has a configuration substantially similar to that of the second embodiment.
- the gate insulating film 1 2 1 4 is required to have a withstand voltage during a memory rewrite operation.
- the thickness T2 has a lower limit.
- the thickness ⁇ 1 of the insulating film 1241 can be made smaller than ⁇ 2, regardless of the demand for the withstand voltage.
- the degree of freedom in design for ⁇ 1 is high for the following reasons.
- the charge holding film (silicon nitride film 124)
- the insulating film 1 2 4 1 that separates 2) from the channel region or the wetting region 1 2 1 1 has a gate electrode 1 2 7 and a channel region or a wetting layer! It is not sandwiched between the areas 1 2 1 1. Therefore, the gate electrode 12 17 and the gate electrode 12 are provided on the insulating film 12 4 1 separating the charge retention film (silicon nitride film 12 4 2) and the channel region or the hetero region 12 11.
- a high electric field acting between the channel region and the weno region 1 211 does not directly act, but a relatively weak electric field spreading laterally from the good electrode 127 acts. Therefore, T 1 can be made thinner than T 2 irrespective of the demand for the withstand voltage for the insulating film 124 1.
- T1 By making T1 thinner, it becomes easier to inject electric charges into the memory function bodies 1261 and 1262, lowering the voltage of the write and erase operations, or speeding up the write and erase operations In addition, the amount of charge induced in the channel region or the U-W shell region 1 211 when the charge is accumulated in the silicon nitride film 1242 increases, so that the memory effect is increased. Can be.
- an insulating film that separates a floating gate from a channel region or a Ueno I region is Since it is sandwiched between the gate electrode (control gate) and the channel region or the weenor region, a high electric field from the gate electrode acts directly. Therefore, in the EEPROM, the thickness of the insulating film that separates the floating gate from the channel region or the ⁇ ! Region is limited, and the optimization of the function of the memory element is hindered.
- the voltage of the write operation and the erase operation can be reduced, or the write operation and the erase operation can be speeded up without lowering the withstand voltage performance of the memory. It is possible to increase the memory effect.
- the thickness T1 of the insulating film is 0.8 nm or more, which is a limit at which uniformity and film quality due to the manufacturing process can be maintained at a certain level and retention characteristics are not extremely deteriorated. Is more preferable.
- the nonvolatile memory of the present invention is mixedly mounted on a liquid crystal driver LSI for image adjustment, in the memory device of the present invention, the charge retention film (silicon nitride film 124) and the channel are independent of the gate insulating film thickness.
- the thickness of the insulating film separating the region or the weinole region can be optimally designed.
- the memory element in the semiconductor memory device of this embodiment has a thickness of an insulating film that separates the charge holding film (silicon nitride film 1242) from the channel region or the region. Except that (T 1) is thicker than the thickness (T 2) of the gate insulating film, it has substantially the same configuration as the second embodiment.
- the thickness T 2 of the gate insulating film 1 2 14 has an upper limit due to the demand for preventing the short channel effect of the device.
- the thickness T 1 of the insulating film can be made larger than T 2, regardless of the need to prevent the short channel effect.
- miniaturization scale When one ring advances (when the gate insulating film becomes thinner), the charge retention film (silicon nitride II) is independent of the thickness of the gate insulating film and the channel region or the cyano region. Since the thickness of the insulating film that separates the memory function can be optimally designed, there is an effect that the memory function body does not hinder the scaling.
- T1 in this memory element the reason for the high degree of freedom in the design of T1 in this memory element is that, as described above, the insulating film that separates the charge retention film from the channel region or the cell region forms the gate electrode and the channel region or the cell region. It is because it is not sandwiched between the area. Therefore, T 1 can be made thicker than T 2 irrespective of the requirement for the gate insulating film to prevent the short channel effect.
- T1 By increasing T1, it is possible to prevent the charge accumulated in the memory function body from being dissipated and to improve the memory retention characteristics.
- T 1> T 2 it is possible to improve the retention characteristics without deteriorating the short channel effect of the memory.
- the thickness ⁇ 1 of the insulating film is preferably 20 nm or less in consideration of a decrease in the rewriting speed.
- a selected gate electrode forms a write / erase gut electrode, and a gate insulating film (including a floating gate) corresponding to the write / erase gut electrode ) also serves as a charge storage film.
- a gate insulating film including a floating gate
- the thickness cannot be reduced to about 7 nm or less), which makes the miniaturization difficult.
- miniaturization of the physical gate length is not expected to be less than about 0.2 microns.
- T1 and T2 can be individually designed as described above, so that miniaturization is possible.
- T 2 4 nm
- the reason why the short channel effect does not occur even if T2 is set thicker than a normal logic transistor is that the source / drain This is because the application area is offset.
- the electrode for assisting writing and erasing and the channel region or the well are provided on the insulating film separating the charge holding film and the channel region or the gel region.
- the high electric field acting between the regions does not act directly, only the relatively weak electric field spreading laterally from the gate electrode acts. Therefore, it is possible to realize a memory element having a gate length finer than or equal to the gut length of the logic transistor for the same processing accuracy.
- This embodiment relates to a change in electrical characteristics when a memory element of a semiconductor memory device is rewritten.
- the memory element constituting the semiconductor memory element of the present invention can particularly increase the drain current ratio at the time of writing and at the time of erasing.
- FIG. 20 is a block diagram showing a semiconductor memory device according to a tenth embodiment of the present invention including a memory cell array using the memory element shown in FIG. 1 as a memory cell.
- the semiconductor memory device includes a memory cell array 21, a positive polarity power supply selection circuit 22, and a voltage polarity inversion circuit 26.
- the input voltage (positive voltage) externally supplied to the memory cell array 21 is applied to the input terminal, and the output terminal is connected to the input terminal of the memory cell array 21.
- a third switch SW3 having an input terminal connected to the pump output terminal of the charge pump 23 and an output terminal connected to the input terminal of the memory cell array 21, and the input voltage being lower than a predetermined voltage.
- An input voltage judging circuit 24 for judging the presence or absence is provided, and a control circuit 25 for turning on / off the first, second, and third switches SW1, SW2, and SW3.
- the predetermined voltage is, for example, an operation voltage at which the operation of the memory cell array 21 is guaranteed.
- the control circuit 25 turns on the first switch SW1 and turns off the second and third switches SW2 and SW3. Thus, an external input voltage is supplied to the memory cell array 21 via the first switch SW1.
- the input voltage determination circuit 24 determines that the input voltage is equal to or lower than a predetermined voltage.
- the first switch SW1 is turned off and the second and third switches SW2 and SW3 are turned on, the voltage with the correct voltage level is supplied from the charge pump 23 to the memory cell array 21. Supplied to
- the voltage polarity inversion circuit 26 is used to generate a negative voltage.
- the voltage polarity inversion circuit 26 in which the input terminal is connected to the output terminal of the first switch SW 1 inverts the polarity of the voltage input to the input terminal and outputs the inverted voltage to the memory cell array 21.
- the absolute value of the voltage does not change, and only the polarity is reversed.
- the absolute value of the voltage is not changed, and the voltage polarity determination circuit that inverts only the polarity of the voltage is employed.
- the present invention is not necessarily limited to this.
- the absolute value of the determined voltage may change.
- FIG. 21 shows a switch circuit as an example of the first, second, and third switches SW1, SW2, and SW3.
- this switch circuit includes a first P-channel field-effect transistor 31 having an input voltage Vin applied to its source, and a drain connected to the first P-channel field-effect transistor 31.
- a second P-channel field-effect transistor 32 whose drain is connected and whose source forms an output terminal, and a gate of the first P-channel field-effect transistor 31 is connected to a source or ground (ground) according to a control signal.
- a first voltage level shifter 33 selectively connected to one of the two, and a gate of the second P-channel field effect transistor 32 selectively connected to either the source or ground (ground) according to a control signal.
- a second voltage level shifter 34 to be connected.
- the switch circuit shown in FIG. 21 is not necessarily used, and a switch circuit having another configuration may be used.
- FIG. 22 shows an example of the charge pump 23 shown in FIG.
- this charge pump includes a transistor 41 having one end to which an input voltage Vin is applied, a transistor 42 having one end connected to the gate of the transistor 41, and a transistor 42 having one end connected to the gate of the transistor 41.
- a transistor 43 having one end connected to the gate, a transistor 44 having a gate connected to the other end of the transistor 41, and an input voltage Vin applied to one end, and a transistor 43 having the other end connected to the other end of the transistor 44.
- a transistor 45 having one end connected and the other end of the transistor 42 connected to the gate; and a transistor having one end connected to the other end of the transistor 45 and a gate connected to the other end of the transistor 43.
- One end is connected to the transistor 46, one end is connected to the other end of the transistor 46, and one end is connected to the gut, and one end is connected to the gate of the transistor 44.
- One end is connected to the capacitor C11 to which the clock signal is applied, the other end is connected to the gate of the transistor 45, and the other end is connected to the capacitor C12 to which the clock signal ⁇ 2 is applied, and one end is connected to the gate of the transistor 46.
- the other end of the transistor C4 is connected to a capacitor C13 having one end connected to the clock signal ⁇ 1 and the other end of the transistor C4 having the clock signal ⁇ 2 applied thereto.
- One end is connected to the other end of the transistor 45, a capacitor C22 to which the clock signal ⁇ is applied to the other end, and one end is connected to the other end of the transistor 46, and the other end is closed. It has a capacitor C23 to which the signal ⁇ 2 is applied.
- One end of the transistor 42 and the other end of the transistor 44 are connected.
- one end of the transistor 43 is connected to the other end of the transistor 45, and the gate of the transistor 43 is connected to a transistor. 4 Connected to the other end of 6.
- An output voltage Vout is output from the other end of the transistor 47.
- the charge pump having the above configuration operates the transistors 41 to 46 in response to the two-phase clock signals ⁇ ⁇ , 2 having different phases to sequentially accumulate large charges in the capacitors C 21, C 22, and C 23. As a result, a boosted output voltage Vout is output from the other end of the transistor 47.
- the charge pump circuit shown in FIG. 22 is not necessarily used, and a charge pump having another circuit configuration may be used.
- FIG. 23 shows an example of the voltage polarity inversion circuit 26 shown in FIG.
- the voltage polarity reversing circuit includes a switch 51 having an input voltage Vin applied to a negative terminal, one end connected to the other end of the switch 51, and the other end grounded.
- An output voltage Vout is output from the other end of the switch 54.
- the switches 51 and 53 are turned on and off by a clock signal ⁇ ⁇ , and the switches 52 and 54 are turned on and off by a clock signal ⁇ (opposite phase with the clock signal ⁇ )).
- a clock signal ⁇ A when the clock signal ⁇ A is at a high level, charge is accumulated in the capacitor C31, and when the clock signal ⁇ goes to a high level when the clock signal ⁇ is at a low level, the charge redistribution law As a result, part of the charge stored in the capacitor C31 moves to the capacitor C32. Then, the charge redistribution is repeated by the clock signals ⁇ ⁇ and ⁇ ⁇ , so that an output voltage Vout having the same absolute value as the input voltage Vin and the opposite polarity is obtained across the capacitor C32.
- the use of the voltage polarity inversion circuit shown in FIG. 22 is not always limited, and a switch circuit having another configuration may be used.
- FIG. 24 is a flowchart illustrating the operation of the semiconductor memory device according to the tenth embodiment. And shows a procedure for operating the control circuit 25 shown in FIG.
- step S1 the voltage level of the input voltage is detected by the input voltage determination circuit 24, and it is determined whether the input voltage detected in step S2 is equal to or lower than a predetermined voltage. If it is determined in step S2 that the input voltage is equal to or lower than the predetermined voltage, the process proceeds to step S3, in which the switch SW1 is turned off, the switches SW2 and SW3 are turned on, and the process ends.
- step S2 determines whether the input voltage exceeds the predetermined voltage. If it is determined in step S2 that the input voltage exceeds the predetermined voltage, the process proceeds to step S4, where the switches SW1 and SW3 are turned on, and the switches SW2 and SW3 are turned off.
- the predetermined voltage to a voltage in the range of +3 V to +12 V, it is possible to supply an appropriate voltage and a sufficient current to a memory element as a memory cell constituting the memory cell array 21. Becomes possible.
- a negative voltage is supplied to the gate electrode during an erase operation of a memory element as a memory cell
- a positive voltage is converted to a negative voltage by the voltage polarity inverting circuit 26, and a positive voltage is applied to the drain electrode and a negative electrode is applied to the gate electrode.
- FIG. 25 is a block diagram of the semiconductor memory device according to the eleventh embodiment of the present invention.
- the eleventh embodiment when a negative voltage is applied to the good electrode of the memory element constituting the memory cell at the time of erasing, it is assumed that a sufficient current for erasing is supplied without externally supplying a voltage. However, in the first embodiment, it is assumed that a sufficient current cannot be obtained from the voltage polarity inversion circuit 26 shown in FIG.
- the eleventh embodiment includes a memory cell array 21 and a positive power supply selection circuit 22 having the same configuration as the semiconductor memory device of the tenth embodiment shown in FIG. A negative power supply selection circuit 70 for negative voltage is provided in place of 26.
- the negative polarity power supply selection circuit 70 has the same configuration as the positive polarity power supply selection circuit 22, and includes first to third switches SW1 to SW3 using P-channel field-effect transistors shown in FIG. It is composed of fourth to sixth switches using N-channel field effect transistors instead of SW3. That is, the negative polarity power supply selection circuit 70 includes a fourth switch in which an input voltage (negative voltage) supplied from an external power supply is applied to an input terminal and an output terminal is connected to an input terminal of a memory cell array; A fifth switch in which an input voltage (negative voltage) is applied to the input terminal, a second charge pump in which a pump input terminal is connected to an output terminal of the fifth switch, and a second switch in which the second charge pump is connected.
- a sixth switch having an input terminal connected to the pump output terminal and an output terminal connected to the input terminal of the memory cell array, and determining whether the input voltage (negative voltage) is equal to or higher than a second predetermined voltage;
- a second input voltage determination circuit for determining, and a second control circuit for controlling on / off of the fourth, fifth, and sixth switches.
- the fourth switch when the second input voltage determination circuit determines that the input voltage (negative voltage) is equal to or less than the second predetermined voltage (absolute value of the voltage is large), the fourth switch is turned on. Turns on, turns off the fifth and sixth switches, and supplies an external voltage to the memory cell array 21. On the other hand, if the input voltage (negative voltage) exceeds the second predetermined voltage (the absolute value of the voltage is small), the second input voltage determination circuit turns off the fourth switch, and the fifth and sixth switches Is turned on, and the accurate negative voltage is supplied to the memory cell array 21 from the second charge pump.
- the charge pump 23 is the first charge pump
- the input voltage determination circuit 24 is the first input voltage determination circuit.
- the control circuit 25 is a first control circuit, and the predetermined voltage when the input voltage determination circuit 24 determines the input voltage (positive voltage) is a first predetermined voltage. Therefore, when a positive voltage and a negative voltage are supplied to the memory cell array 21, a sufficient current can be supplied while having the same effects as those of the semiconductor memory device of the tenth embodiment. Further, by using a switch circuit having the configuration shown in FIG. 21 for the first to sixth switches, it is possible to realize a small circuit area, and to realize a positive power supply selection circuit 22 and a negative power supply selection circuit 7. 0 works exactly.
- the first predetermined voltage of the positive polarity power supply selection circuit 22 is set to a voltage within a range of +3 V to +12 V
- the second predetermined voltage of the negative polarity power supply selection circuit 70 is set to 13 V to By setting the voltage within the range of 112 V, an appropriate voltage and a sufficient current can be supplied to a memory element as a memory cell included in the memory cell array 21.
- a rewritable nonvolatile memory for adjusting an image of a liquid crystal panel can be cited.
- the liquid crystal panel 701 shown in FIG. 26 is driven by a liquid crystal driver 702.
- the liquid crystal driver 702 includes a nonvolatile memory section 703 as a semiconductor memory device, an SRAM section 704, and a liquid crystal driver circuit 705.
- the nonvolatile memory section 703 includes the nonvolatile memory element of the present invention, and is preferably made of the semiconductor memory device described in the tenth and eleventh embodiments.
- the nonvolatile memory section 703 has a configuration that can be rewritten from outside.
- the information stored in the nonvolatile memory unit 703 is transferred to the SRAM unit 704 when the power of the device is turned on.
- the liquid crystal driver circuit 705 can read stored information from the SRAM section 704 as needed. By providing the SRAM unit, the storage information can be read at a very high speed.
- the liquid crystal driver 702 may be externally attached to the liquid crystal panel 701 as shown in FIG. 26, but may be formed on the liquid crystal panel 701.
- the liquid crystal panel changes the displayed gray scale by applying multiple levels of voltage to each pixel, but the relationship between the applied voltage and the displayed gray scale varies from product to product. Therefore, by storing information for correcting the variation of each product after the product is completed, and performing correction based on the information, the image quality between products can be made uniform. Therefore, it is preferable that a rewritable nonvolatile memory for storing the correction information be mounted on the liquid crystal driver. Originally developed as this nonvolatile memory It is preferable to use a clear nonvolatile memory element. In particular, it is preferable to use the semiconductor memory devices described in the tenth and eleventh embodiments in which the nonvolatile memory element of the present invention is integrated.
- the process of mixing the circuit with a circuit such as a liquid crystal driver can be easily performed, so that manufacturing cost can be reduced.
- the semiconductor memory devices described in the tenth and eleventh embodiments are particularly suitable when the memory scale is relatively small and reliability and stability are important.
- a nonvolatile memory for adjusting an image of a liquid crystal panel is, for example, several kilobytes, and has a relatively small memory size. Therefore, it is particularly preferable to use the semiconductor memory device according to the tenth and eleventh embodiments as a nonvolatile memory for adjusting an image of a liquid crystal panel.
- FIG. 27 is a schematic block diagram of a mobile phone as an example of the mobile electronic device according to the thirteenth embodiment of the present invention.
- This mobile phone has a control circuit 74, a battery 77, and an R F as shown in FIG.
- a (radio frequency) circuit 75, a display section 72, an antenna 71, a signal line 73, and a power line 76 are provided.
- the control circuit 74 incorporates the semiconductor storage devices 74a of the tenth and eleventh embodiments. It is desirable that the control circuit 74 be an integrated circuit in which elements having the same structure are used as both memory elements and logic circuit elements. As a result, the manufacture of integrated circuits is facilitated, and the manufacturing cost of portable electronic devices can be particularly reduced.
- the portable electronic device can be downsized, Reliability can be improved. In addition, manufacturing cost can be reduced by miniaturization.
- the gate electrode formed on the semiconductor layer via the gate insulating film, the channel region disposed under the gate electrode, and both sides of the channel region A diffusion region having a conductivity type opposite to that of the channel region; and a memory function body formed on both sides of the gate electrode and having a function of retaining charges.
- the memory element composed of is used as the memory cell, the memory element used as the memory cell is not limited to this.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/528,997 US7203118B2 (en) | 2002-09-26 | 2003-09-10 | Semiconductor storage device and mobile electronic device |
AU2003262049A AU2003262049A1 (en) | 2002-09-26 | 2003-09-10 | Semiconductor storage device and mobile electronic device |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2002-280806 | 2002-09-26 | ||
JP2002280806 | 2002-09-26 | ||
JP2003142146A JP2004164811A (ja) | 2002-09-26 | 2003-05-20 | 半導体記憶装置および携帯電子機器 |
JP2003-142146 | 2003-05-20 |
Publications (1)
Publication Number | Publication Date |
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WO2004029985A1 true WO2004029985A1 (ja) | 2004-04-08 |
Family
ID=32044622
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/JP2003/011559 WO2004029985A1 (ja) | 2002-09-26 | 2003-09-10 | 半導体記憶装置および携帯電子機器 |
Country Status (6)
Country | Link |
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US (1) | US7203118B2 (ja) |
JP (1) | JP2004164811A (ja) |
AU (1) | AU2003262049A1 (ja) |
MY (1) | MY134198A (ja) |
TW (1) | TWI235383B (ja) |
WO (1) | WO2004029985A1 (ja) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100558551B1 (ko) * | 2003-12-22 | 2006-03-10 | 삼성전자주식회사 | 불휘발성 메모리 소자에서의 전원 검출장치 및 그에 따른검출방법 |
DE102005055834A1 (de) * | 2005-11-23 | 2007-05-24 | Infineon Technologies Ag | Speicherschaltung, Ansteuerschaltung für einen Speicher und Verfahren zum Einschreiben von Schreibdaten in einen Speicher |
JP2008021355A (ja) | 2006-07-12 | 2008-01-31 | Renesas Technology Corp | 半導体装置 |
US7605579B2 (en) * | 2006-09-18 | 2009-10-20 | Saifun Semiconductors Ltd. | Measuring and controlling current consumption and output current of charge pumps |
US8203325B2 (en) | 2007-09-07 | 2012-06-19 | Analog Devices, Inc. | Activation systems and methods to initiate HDMI communication with mobile sources |
JP2009076731A (ja) * | 2007-09-21 | 2009-04-09 | Renesas Technology Corp | 半導体装置およびその製造方法 |
US7928695B2 (en) * | 2008-04-15 | 2011-04-19 | Hycon Technology Corp. | Rechargeable battery protection device |
WO2011125456A1 (en) * | 2010-04-09 | 2011-10-13 | Semiconductor Energy Laboratory Co., Ltd. | Semiconductor device |
US8981535B2 (en) | 2013-04-30 | 2015-03-17 | Robert Bosch Gmbh | Charge pump capacitor assembly with silicon etching |
US10497430B2 (en) | 2016-06-22 | 2019-12-03 | Samsung Electronics Co., Ltd. | Semiconductor devices, circuits and methods for read and/or write assist of an SRAM circuit portion based on power supply voltage detection circuits |
US10403384B2 (en) | 2016-06-22 | 2019-09-03 | Darryl G. Walker | Testing a semiconductor device including a voltage detection circuit and temperature detection circuit that can be used to generate read assist and/or write assist in an SRAM circuit portion and method therefor |
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JPH11219596A (ja) * | 1998-02-03 | 1999-08-10 | Nec Corp | 半導体装置の電源回路 |
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JPH05304277A (ja) | 1992-04-28 | 1993-11-16 | Rohm Co Ltd | 半導体装置の製法 |
JP3362873B2 (ja) * | 1992-08-21 | 2003-01-07 | 株式会社東芝 | 半導体装置 |
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JP3346273B2 (ja) * | 1998-04-24 | 2002-11-18 | 日本電気株式会社 | ブースト回路および半導体記憶装置 |
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2003
- 2003-05-20 JP JP2003142146A patent/JP2004164811A/ja active Pending
- 2003-09-10 WO PCT/JP2003/011559 patent/WO2004029985A1/ja active Application Filing
- 2003-09-10 US US10/528,997 patent/US7203118B2/en not_active Expired - Lifetime
- 2003-09-10 AU AU2003262049A patent/AU2003262049A1/en not_active Abandoned
- 2003-09-25 MY MYPI20033666A patent/MY134198A/en unknown
- 2003-09-26 TW TW092126664A patent/TWI235383B/zh not_active IP Right Cessation
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JP2000500892A (ja) * | 1995-11-13 | 2000-01-25 | レクサー・マイクロシステムズ・インコーポレーテッド | 複数電圧印加における自動電圧検出 |
JPH11219596A (ja) * | 1998-02-03 | 1999-08-10 | Nec Corp | 半導体装置の電源回路 |
JP2000244298A (ja) * | 1999-02-17 | 2000-09-08 | Toshiba Corp | アナログスイッチ回路 |
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JP2002157894A (ja) * | 2000-11-21 | 2002-05-31 | Toshiba Corp | 半導体記憶装置 |
Also Published As
Publication number | Publication date |
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TW200423137A (en) | 2004-11-01 |
US7203118B2 (en) | 2007-04-10 |
TWI235383B (en) | 2005-07-01 |
US20060109729A1 (en) | 2006-05-25 |
AU2003262049A1 (en) | 2004-04-19 |
JP2004164811A (ja) | 2004-06-10 |
MY134198A (en) | 2007-11-30 |
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