WO2008156215A1 - Mos semiconductor memory device - Google Patents
Mos semiconductor memory device Download PDFInfo
- Publication number
- WO2008156215A1 WO2008156215A1 PCT/JP2008/061679 JP2008061679W WO2008156215A1 WO 2008156215 A1 WO2008156215 A1 WO 2008156215A1 JP 2008061679 W JP2008061679 W JP 2008061679W WO 2008156215 A1 WO2008156215 A1 WO 2008156215A1
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- WO
- WIPO (PCT)
- Prior art keywords
- insulating film
- film
- semiconductor memory
- memory device
- type semiconductor
- Prior art date
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 236
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 135
- 229910052710 silicon Inorganic materials 0.000 claims description 135
- 239000010703 silicon Substances 0.000 claims description 135
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 112
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 112
- 238000000034 method Methods 0.000 claims description 69
- 238000005381 potential energy Methods 0.000 claims description 40
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 38
- 239000000203 mixture Substances 0.000 claims description 26
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 22
- 229910052757 nitrogen Inorganic materials 0.000 claims description 19
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 16
- 229910044991 metal oxide Inorganic materials 0.000 claims description 15
- 150000004706 metal oxides Chemical class 0.000 claims description 15
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 11
- 229910052760 oxygen Inorganic materials 0.000 claims description 11
- 239000001301 oxygen Substances 0.000 claims description 11
- 239000012528 membrane Substances 0.000 claims description 4
- 238000013500 data storage Methods 0.000 abstract 1
- 239000010408 film Substances 0.000 description 857
- 239000007789 gas Substances 0.000 description 167
- 239000000758 substrate Substances 0.000 description 89
- 239000010410 layer Substances 0.000 description 70
- 238000012545 processing Methods 0.000 description 68
- 230000001965 increasing effect Effects 0.000 description 50
- 230000014759 maintenance of location Effects 0.000 description 36
- 238000010586 diagram Methods 0.000 description 34
- 238000009792 diffusion process Methods 0.000 description 23
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 19
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- 230000015572 biosynthetic process Effects 0.000 description 17
- 230000003647 oxidation Effects 0.000 description 17
- 238000003860 storage Methods 0.000 description 17
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 16
- 230000008569 process Effects 0.000 description 16
- 238000005229 chemical vapour deposition Methods 0.000 description 13
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 125000006850 spacer group Chemical group 0.000 description 11
- 239000000463 material Substances 0.000 description 10
- 230000007246 mechanism Effects 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 8
- 238000003949 trap density measurement Methods 0.000 description 8
- 230000005641 tunneling Effects 0.000 description 8
- 238000000151 deposition Methods 0.000 description 6
- 238000009413 insulation Methods 0.000 description 6
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 230000008021 deposition Effects 0.000 description 5
- 239000011261 inert gas Substances 0.000 description 5
- 238000002347 injection Methods 0.000 description 5
- 239000007924 injection Substances 0.000 description 5
- 239000011810 insulating material Substances 0.000 description 5
- 238000005121 nitriding Methods 0.000 description 5
- 229910000077 silane Inorganic materials 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000006870 function Effects 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 229910052726 zirconium Inorganic materials 0.000 description 3
- PFTIVKCRALCOLB-UHFFFAOYSA-N [SiH4].[N] Chemical compound [SiH4].[N] PFTIVKCRALCOLB-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- BOXDGARPTQEUBR-UHFFFAOYSA-N azane silane Chemical compound N.[SiH4] BOXDGARPTQEUBR-UHFFFAOYSA-N 0.000 description 2
- 238000004140 cleaning Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- PZPGRFITIJYNEJ-UHFFFAOYSA-N disilane Chemical compound [SiH3][SiH3] PZPGRFITIJYNEJ-UHFFFAOYSA-N 0.000 description 2
- 230000005284 excitation Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000002784 hot electron Substances 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052451 lead zirconate titanate Inorganic materials 0.000 description 2
- SYHGEUNFJIGTRX-UHFFFAOYSA-N methylenedioxypyrovalerone Chemical compound C=1C=C2OCOC2=CC=1C(=O)C(CCC)N1CCCC1 SYHGEUNFJIGTRX-UHFFFAOYSA-N 0.000 description 2
- HDZGCSFEDULWCS-UHFFFAOYSA-N monomethylhydrazine Chemical compound CNN HDZGCSFEDULWCS-UHFFFAOYSA-N 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 229910021332 silicide Inorganic materials 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 229910052721 tungsten Inorganic materials 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- -1 Nitrogen nitrides Chemical class 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- VOSJXMPCFODQAR-UHFFFAOYSA-N ac1l3fa4 Chemical compound [SiH3]N([SiH3])[SiH3] VOSJXMPCFODQAR-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000003491 array Methods 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- VUSQXHIQCFUDHK-UHFFFAOYSA-N bismuth tantalum Chemical compound [Ta][Bi] VUSQXHIQCFUDHK-UHFFFAOYSA-N 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 208000037998 chronic venous disease Diseases 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000005672 electromagnetic field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- HFGPZNIAWCZYJU-UHFFFAOYSA-N lead zirconate titanate Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ti+4].[Zr+4].[Pb+2] HFGPZNIAWCZYJU-UHFFFAOYSA-N 0.000 description 1
- 238000004518 low pressure chemical vapour deposition Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 125000004430 oxygen atom Chemical group O* 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000000790 scattering method Methods 0.000 description 1
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 1
- PBCFLUZVCVVTBY-UHFFFAOYSA-N tantalum pentoxide Inorganic materials O=[Ta](=O)O[Ta](=O)=O PBCFLUZVCVVTBY-UHFFFAOYSA-N 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- RUDFQVOCFDJEEF-UHFFFAOYSA-N yttrium(III) oxide Inorganic materials [O-2].[O-2].[O-2].[Y+3].[Y+3] RUDFQVOCFDJEEF-UHFFFAOYSA-N 0.000 description 1
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
- H01L29/68—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
- H01L29/792—Field effect transistors with field effect produced by an insulated gate with charge trapping gate insulator, e.g. MNOS-memory transistors
-
- 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
- H01L29/40117—Multistep manufacturing processes for data storage electrodes the electrodes comprising a charge-trapping insulator
-
- 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
- H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
- H01L29/51—Insulating materials associated therewith
- H01L29/511—Insulating materials associated therewith with a compositional variation, e.g. multilayer structures
- H01L29/513—Insulating materials associated therewith with a compositional variation, e.g. multilayer structures the variation being perpendicular to the channel plane
Definitions
- the present invention relates to a MO S (Metal — O xide — Si 1 icon) type semiconductor memory device, and in particular, a MO S having a plurality of insulating films having different band gap sizes between a substrate and an electrode layer.
- MO S Metal — O xide — Si 1 icon
- E E P ROM (E l c t r i c a 1 1 y E r a s a b l e a n d P r o g r a mm a b l e R OM) capable of electrical rewriting operation.
- E E P ROM E l c t r i c a 1 1 y E r a s a b l e a n d P r o g r a mm a b l e R OM
- Patent Document 1 a voltage is applied between the semiconductor substrate and the control gate electrode, and the insulating film (insulating film laminated body) of the above-mentioned stacked structure is mainly in the silicon nitride film or the silicon nitride film and the upper and lower sides thereof. By accumulating electrons or holes at the interface with the silicon oxide film, data of “1” and “0” is rewritten.
- the prior art will be described by taking as an example the case of injecting electrons into an insulating film stack as a charge storage region.
- 0 V is applied to the semiconductor substrate, and, for example, 10 V is applied to the control gate electrode.
- semiconductor A strong electric field is applied to the insulating film stack between the body substrate and the control gate electrode, and electrons are injected from the semiconductor substrate into the silicon nitride film through the lower silicon oxide film by a tunnel phenomenon.
- the injected electrons are mainly trapped in the silicon nitride film or near the interface between the silicon nitride film and the lower silicon oxide film or the upper silicon oxide film. Accumulated.
- an important performance required for a nonvolatile semiconductor memory device such as E EP PROM is data retention characteristics.
- E EP PROM electronic programmable read-only memory
- electrons trapped in the silicon nitride film or near the interface between the silicon nitride film and the lower silicon oxide film or the upper silicon oxide film are stable for a long time.
- the upper and lower silicon oxide films had to be formed thick.
- the thickness of the upper and lower silicon oxide films is increased, there is a problem that the data writing speed becomes slow because the electric field applied to the insulating film stack becomes weak when writing data.
- Patent Document 1 Japanese Patent Laid-Open No. 2 0 0 2 — 2 0 3 9 1 7 (for example, FIG. 1, FIG. 2, etc.) Disclosure of the Invention
- the data retention characteristic is improved, the data write speed is reduced. Will fall.
- the power consumption increases and the probability of occurrence of dielectric breakdown increases and the reliability of the semiconductor memory device decreases.
- the present invention has been made in view of the above circumstances, and has an excellent data retention characteristic, high-speed data rewriting performance, low power consumption operation performance, and high reliability at the same time.
- An object is to provide an S-type semiconductor memory device.
- the MOS type semiconductor memory device of the present invention is a MOS type semiconductor memory device in which an insulating film stack in which a plurality of insulating films are stacked as a region for accumulating charges is provided between a semiconductor layer and a gate electrode.
- the insulating film constituting the insulating film stack is provided at a position closest to the lower insulating film and the gate electrode provided at the position closest to the semiconductor layer.
- the upper insulating film has a larger band gap than two or more insulating films interposed between them.
- the insulating film stack includes a second insulating film having a smaller band gap than the lower insulating film between the lower insulating film and the upper insulating film, A third insulating film having a larger band gap than the second insulating film and a fourth insulating film having a smaller band gap than the third insulating film may be provided.
- the insulating film stack includes a second insulating film having a smaller band gap than the lower insulating film between the lower insulating film and the upper insulating film, A third insulating film having a smaller band gap than the second insulating film; and a fourth insulating film having a larger band gap than the third insulating film; , May be provided.
- the insulating film stack includes the second insulating film, the third insulating film, and the fourth insulating film between the lower insulating film and the upper insulating film.
- An intermediate laminate including the insulating film may be repeatedly formed.
- the lower insulating film may be provided in contact with the semiconductor layer, or the lower insulating film is provided in contact with the semiconductor layer.
- the fifth insulating layer may be provided via the second electrode layer provided in contact with the fifth insulating layer.
- the lower insulating film and the upper insulating film are silicon oxide films, the second insulating film, the third insulating film, and the fourth insulating film.
- a silicon nitride film, a silicon nitride oxide film, or a metal oxide film may be used.
- the third insulating film is formed in the thickness direction of the film from the semiconductor layer side to the gate electrode side and in the vicinity of the interface with the second insulating film.
- it may have an energy band structure in which the band gap at the center of the film is larger than that near the interface with the fourth insulating film.
- the third insulating film is a silicon nitride oxide film, and in the thickness direction of the film from the semiconductor layer side to the gate electrode side, the composition ratio of oxygen to nitrogen in the film is Compared with the vicinity of the interface with the second insulating film and the vicinity of the interface with the fourth insulating film, the center of the film has a large oxygen concentration profile.
- the third insulating film is an interface with the second insulating film in a thickness direction of the film from the semiconductor layer side to the gate electrode side.
- the band gap at the center of the film is small in energy. It may have a band structure.
- the third insulating film is a silicon nitride film, and the composition ratio of nitrogen to silicon in the film in the thickness direction of the film from the semiconductor layer side to the gate electrode side is the second insulating film.
- it has a large nitrogen concentration profile in the center of the film.
- the film thickness of the second insulating film and the fourth insulating film may be smaller than the film thickness of the third insulating film.
- the lower insulating film and the upper insulating film may have a film thickness in the range of 0.5 nm to 20 nm.
- the electron potential energy in the conduction band of the semiconductor layer is higher at the time of data writing than the electron potential energy in the conduction band of the second insulating film, and the data reading It may be low at times and when holding data.
- the semiconductor layer is a columnar silicon layer, and has a vertical stacked structure in which the insulating film stacked body and the gate electrode are provided on the side thereof. Also good.
- the N A N D type memory cell array of the present invention is characterized in that the above-described MOS type semiconductor memory devices are arranged in series.
- the NOR type memory cell array of the present invention is characterized in that the MOS type semiconductor memory devices are arranged in parallel.
- the lower and upper insulating films located closest to the semiconductor layer side and the most gate electrode side are: Between these It has a larger band gap than existing insulating films. For this reason, the tunnel phenomenon tends to cause charge injection from the semiconductor layer to the insulating film stack. Therefore, when writing data, it is possible to write quickly without reducing the tunneling probability. In addition, since the voltage required for writing can be kept small, the generation of electron-hole pairs due to impact ionization can be reduced even with an applied voltage, and dielectric breakdown is unlikely to occur. Therefore, it is not necessary to apply a high voltage for writing data overnight, operation with low power consumption is possible, and high reliability is ensured.
- the lower and upper insulating films located on the most semiconductor layer side and the most gate electrode side have large band gaps, it is possible to prevent the charges held between them from being released. Therefore, excellent data retention characteristics can be obtained without increasing the thickness of the insulating film located on the most semiconductor layer side and the most gate electrode side.
- the MOS type semiconductor memory device of the present invention has both excellent data retention characteristics, high-speed data rewriting performance, low power consumption operation performance, and high reliability at the same time. is there. Brief Description of Drawings
- FIG. 1 is an explanatory diagram showing a schematic configuration of a MOS semiconductor memory device according to the first embodiment of the present invention.
- FIG. 2 is an energy band diagram of the MOS semiconductor memory device shown in FIG.
- FIG. 3 is a schematic cross-sectional view showing an example of a plasma processing apparatus suitable for forming an insulating film.
- FIG. 4 is an explanatory diagram showing a schematic configuration of a MOS type semiconductor memory device according to the second embodiment of the present invention.
- FIG. 5 is an energy band diagram of the MOS type semiconductor memory device shown in FIG.
- FIG. 6 is an explanatory diagram showing a schematic configuration of a MOS type semiconductor memory device according to the third embodiment of the present invention.
- FIG. 7 is an energy band diagram of the MOS type semiconductor memory device shown in FIG.
- FIG. 8 is an explanatory diagram showing a schematic configuration of a MOS type semiconductor memory device according to the fourth embodiment of the present invention.
- FIG. 9 is an energy band diagram of the MOS type semiconductor memory device shown in FIG.
- FIG. 10 is an explanatory diagram showing a schematic configuration of a MOS type semiconductor memory device according to a fifth embodiment of the present invention.
- FIG. 11 is an energy band diagram of the MOS type semiconductor memory device shown in FIG.
- FIG. 12 is an energy band diagram of another example of the MOS type semiconductor memory device shown in FIG.
- FIG. 13 is an explanatory diagram showing a schematic configuration of a MOS type semiconductor memory device according to a sixth embodiment of the present invention.
- Fig. 14 (a) shows an example of an energy diagram in the prior art.
- Figure 14 (b) shows an example of an energy diagram in the prior art.
- Fig. 14 (c) shows an example of an energy diagram in the prior art.
- FIG. 14 (d) is a diagram showing an example of an energy diagram in the present invention.
- Fig. 14 (e) is an example of energy diagram in the present invention. It is a figure which shows
- Fig. 14 (f) is a diagram showing an example of the energy diagram in the present invention.
- Figure 15 shows the plasma C V using ammonia as the deposition source gas.
- FIG. 3 is a graph showing the relationship between the processing pressure and band gap in D.
- FIG. 16 is a graph showing the relationship between the processing pressure and the band gap in plasma C V D using nitrogen as the deposition source gas.
- FIG. 17 is an energy diagram showing a modification of the MOS semiconductor memory device shown in FIG.
- FIG. 18 shows the N A to which the MOS semiconductor memory device of the present invention can be applied.
- FIG. 19 is a cross-sectional view taken along line AA in FIG.
- FIG. 20 is an equivalent circuit diagram of the memory cell array shown in FIG. 18.
- FIG. 21 is a diagram of N O to which the MOS semiconductor memory device of the present invention can be applied.
- FIG. 22 is a cross-sectional view taken along line B-B in FIG.
- FIG. 23 is an equivalent circuit diagram of the memory cell array shown in FIG. 21.
- FIG. 24 is a plan view of a vertical memory cell array to which the MOS semiconductor memory device of the present invention can be applied.
- FIG. 25 is a cross-sectional view taken along line C-C in FIG.
- FIG. 26 is a plan view of a stacked memory cell array to which the MOS semiconductor memory device of the present invention can be applied.
- FIG. 27 is a cross-sectional view taken along line D_D in FIG. BEST MODE FOR CARRYING OUT THE INVENTION
- FIG. 1 is a cross-sectional view showing a schematic configuration of the MOS type semiconductor memory device according to the first embodiment of the present invention.
- Fig. 2 is an energy band diagram of the MOS semiconductor memory device 60 1 in Fig. 1.
- the MOS semiconductor memory device 60 1 of the present embodiment has a p-type silicon substrate 1001 as a semiconductor layer, and is stacked on the p-type silicon substrate 10 0 1.
- the formed insulating film laminate 10 0 2 a composed of a plurality of insulating films having different band gap sizes, and the gate electrode 10 0 formed on the insulating film laminate 10 0 2 a 3 and.
- the first insulating film 1 1 1, the second insulating film 1 1 2, the third insulating film 1 1 3 An insulating film stack body 10 02a having four insulating films 1 1 4 and a fifth insulating film 1 1 5 is provided.
- the silicon substrate 10 0 1 includes a first source drain 1 0 4 and a second drain that are n-type diffusion layers at a predetermined depth from the surface so as to be located on both sides of the gate electrode 10 3.
- the source drains 105 are formed, and a channel forming region 106 is formed between them.
- the MOS type semiconductor memory device 61 may be formed in a p-type silicon layer formed in a semiconductor substrate.
- this embodiment may be implemented with a power p-channel M ⁇ S device, taking an n-channel MOS device as an example. Therefore, the contents of the present embodiment described below can be applied to all n-channel MOS devices and p-channel MOS devices.
- the first insulating film 1 1 1 is, for example, a silicon dioxide film (Si 0 2 film) formed by oxidizing the surface of a silicon substrate 100 1 by a thermal oxidation method. .
- the first insulating film 1 1 1 has an energy band gap in the range of 8 to 10 eV, for example.
- the thickness of the first insulating film 1 1 1 is, for example, preferably in the range of 0.5 nm to 20 nm, more preferably in the range of lnm to 10 nm, and in the range of 1 nm to 3 nm. Good.
- the second insulating film 1 1 2 is a silicon nitride oxide film formed on the surface of the first insulating film 1 1 1 (S i ON film; where the composition ratio of Si and human N is not necessarily the stoichiometric amount. It is not theoretically determined and takes a different value depending on the film formation condition.
- the second insulating film 1 1 2 has an energy band gap in the range of 5 to 7 eV, for example.
- the film thickness of the second insulating film 1 1 2 is, for example, preferably in the range of 2 nm to 20 nm, more preferably in the range of 2 nm to: L O nm, and desirably in the range of 3 nm to 5 nm.
- the third insulating film 1 1 3 is a silicon nitride film formed on the second insulating film 1 1 2 (SiN film; where the composition ratio of S 1 and N is not always determined stoichiometrically. However, the value varies depending on the film formation conditions, and so on.
- This third insulating film 11 13 has an energy band gap in the range of 2.5 to 4 eV, for example.
- the film thickness of the third insulating film 1 13 is preferably in the range of 2 nm to 30 nm, more preferably in the range of 2 nm to 15 nm, and preferably in the range of 4 nm to 10 nm. .
- the fourth insulating film 1 14 is a silicon nitride oxide film (Si ON film) formed on the third insulating film 1 13.
- the fourth insulating film 1 14 has the same energy band gap and film thickness as the second insulating film 1 1 2.
- the fifth insulating film 1 1 5 is formed on the fourth insulating film 1 1 4 by, for example, C VD (Chemical V aor Deposition; This is a silicon dioxide film (S i 0 2 film) deposited by the (phase deposition) method.
- the fifth insulating film 1 15 functions as a block layer (barrier layer) between the electrode 10 3 and the fourth insulating film 1 14. This fifth insulating film 1
- Insulating film 1 1 5 has an energy band gap in the range of 8 to: L 0 e V, for example.
- O 3 ⁇ 4 5 Insulating film 1 1 5 has a film thickness of 2 nm, for example.
- Is preferably in the range of ⁇ 30 nm, more preferably in the range of 2 nm to 15 nm, and preferably in the range of onm to 8 nm.
- the gate electrode 103 is made of, for example, a polycrystalline silicon film formed by the CVD method, and functions as a control gate (CG) electrode.
- the gate electrodes 10 3 are W, Ti, Ta, Cu, A
- the gate electrode 103 is not limited to a single layer, but for the purpose of reducing the specific resistance of the gate electrode 103 and increasing the speed, for example, tungsten, molybdenum, tantalum, titanium, platinum, their silicides, nitrides, alloys This can be achieved by using a laminated structure including The gate electrode 103 is connected to a wiring layer (not shown).
- the first insulating film 11 1 1 and the fifth insulating film 1 15 a silicon nitride oxide film (S i ON film) is also used. properly is Rukoto using silicon dioxide film (S i ⁇ 2 film) is preferable.
- the material of the second insulating film 1 1 2, the third insulating film 1 1 3, and the fourth insulating film 1 1 4 is not limited to silicon nitride and silicon nitride oxide, but is also an insulating material such as a metal oxide Can be used.
- metal oxide examples include ⁇ ⁇ 0 2 , H f-S i 1 0, H f-A l — ⁇ , Z r 0 2 , A 1 2 0 3 , PZT [P b (Z r, T i ) 0 3 ; lead zirconate titanate], BST [(B a, S r) T i 0 3 ], SRO (S r R u 0 3 ), SBT (S r B i 2 Ta 2 0 9 ; Tantalum Bismuth acid strontium), T a 2 0 5 (tantalum pentoxide), B a T i (Barium titanate), T i O 2 YSZ (yttria stabilized zirconium) BIT (B i 4 T i 3 0 12 ) STO (S r T i 03)
- the MOS type semiconductor memory device 6 0 1 includes the band gaps 1 1 1 a and 1 1 5 a of the first insulating film 1 1 1 and the fifth insulating film 1 1 5.
- 2nd insulating film 1 1 2, 3rd insulating film 1 1 3 and 4th insulating film 1 1 4 band gap 1 1 2 a, 1 1 3 a and 1 1 4 Has a larger energy band structure than a.
- a band gap having an intermediate size between the two is also used between the first insulating film 1 1 1 and the fifth insulating film 1 1 5 and the third insulating film 1 1 3 with the smallest band gap.
- a second insulating film 1 1 2 and a fourth insulating film 1 1 4 having a pair 1 1 2 a and 1 1 4 a are interposed.
- reference numeral 10 1 a is a band gap of the silicon substrate 10 1
- reference numeral 1 0 3 a is a band gap of the gate electrode 1 0 3 (FIGS. 5, 7, and 5). 9, the same in Figure 11 and Figure 12).
- the second insulating film 1 1 2 It is preferable to set the thickness of the fourth insulating film 1 14 to be smaller than the thickness of the third insulating film 1 13 so that the Coulomb blockade phenomenon occurs at the time of writing. Furthermore, at the time of writing, for the purpose of increasing the probability of occurrence of a tunnel phenomenon such as FN (Fowler-Nordheim) tunneling and further improving the writing speed, electrons in the conduction band of the silicon substrate 10 0 1 are used. The potential energy is preferably set to be higher than the electron potential energy 1 in the conduction band of the second insulating film 1 1 2.
- the electron potential energy in the conduction band of the silicon substrate 10 1 is lower than the electron potential energy in the conduction band of the second insulating film 1 1 2. It is preferable to set so that In addition, even when data is read out, the electron potential energy in the conduction band of the silicon substrate 10 1 is compared with the electron potential energy in the conduction band of the second insulating film 1 1 2 as in the data retention state. It is preferable to set it to be low.
- Example of operation of MOS semiconductor memory device 6 0 1 with the above structure explain about.
- the first source drain 10 4 and the second source drain 1 0 5 are held at 0 V with reference to the potential of the silicon substrate 10 1, and the gate electrode Apply a predetermined positive voltage to 1 0 3.
- the gate electrode Apply a predetermined positive voltage to 1 0 3.
- electrons are accumulated in the channel formation region 106 to form an inversion layer, and a part of the charge in the inversion layer is laminated via the first insulation film 1 1 1 due to the tunnel phenomenon.
- the electrons that have moved to the insulating film stack 10 2 a are trapped by the charge trapping centers formed inside, and data is accumulated.
- a voltage of 0 V is applied to both the first source 'drain 1 0 4 and the second source' drain 1 0 5 with respect to the potential of the silicon substrate 10 1
- a negative voltage of a predetermined magnitude is applied to the electrodes 1 0 3.
- the electric charge held in the insulating film stack 10 0 2 a is extracted to the channel formation region 1 0 6 of the silicon substrate 1 0 1 through the first insulating film 1 1 1. It is.
- the .MOS type semiconductor memory device 60.sub.1 returns to an erased state in which the amount of accumulated electrons in the insulating film laminate 10.sub.2a is low.
- the method of writing, reading, and erasing information in the MOS type semiconductor memory device 60 1 is not limited, and is different from the above. Writing, reading and erasing may be performed by the following method. For example,
- first source drain 10 4 and the second source 'drain 1 0 5 are not fixed, but they function as alternating sources or drains. The information may be written and read.
- the MOS type semiconductor memory device 60 1 according to the present embodiment has improved data retention characteristics, higher write operation speed, and lower power consumption than the conventional MOS type semiconductor memory device. This is an excellent MOS-type semiconductor memory device that has been realized at the same time and improved reliability.
- the MOS semiconductor memory device 60 1 according to the present embodiment can be manufactured according to a conventional method. Here, an example of a typical procedure will be described. First, for example, L O C O S (L o c a l
- An element isolation film is formed by a method such as an Ox i d a t i o n o f (S i l i c o n) method or a S T I (S h a l l o w T r e n c h I S o l a i t i o n) method.
- a first insulating film 1 1 1 is formed on the surface of the silicon substrate 10 1, for example, by a thermal oxidation method.
- a second insulating film 1 1 2, a third insulating film 1 13, and a fourth insulating film 1 14 are sequentially formed on the first insulating film 1 1 1.
- the silicon nitride film as the third insulating film 1 13 can be formed by, for example, the CVD method.
- the silicon nitride oxide film or the metal oxide film as the second or fourth insulating film 1 1 2 or 1 14 may be formed directly by, for example, the CVD method, or formed by the CVD method. It can be manufactured by oxidizing the silicon nitride film or nitriding the silicon oxide film formed by the CVD method.
- a fifth insulating film 1 1 5 is formed on the fourth insulating film 1 1 4.
- the fifth insulating film 115 can be formed by, for example, a CVD method.
- a polysilicon film, a metal layer, or a metal silicide layer is formed on the fifth insulating film 115 by, for example, a CVD method to form a gate electrode 10 3. Form.
- the photolithographic technique is used to etch the metal film and the fifth to first insulating films 1 15 5 to 11 1 1 using the patterned resist as a mask.
- a gate laminated structure having the gate electrode 10 3 and the insulating film laminated body 10 2 a which are patterned as described above can be obtained.
- n-type impurities are ion-implanted at a high concentration into the silicon surface adjacent to both sides of the gate stacked structure, and the first source 'drain 1 0 4 and the second source' drain 1 0 Form 5.
- the MOS type semiconductor memory device 60 1 having the structure shown in FIG. 1 can be manufactured.
- a method for forming the silicon oxide film, the silicon nitride film, or the silicon nitride oxide film used as the first insulating film 11 1 1 to the fifth insulating film 1 15 is not particularly limited.
- a method such as a thermal oxidation method, a CVD method, or an ALD (A tomic Layer Deposition Method) atomic scattering method or a nitriding method can be selected as appropriate.
- a silicon film may be formed by oxidizing a silicon film by a method such as plasma oxidation, or a silicon nitride film may be formed by nitriding a silicon film by a method such as plasma nitriding. Good.
- a silicon nitride film formed by a C VD method may be nitrided by a method such as a plasma nitriding method to form a silicon nitride oxide film, or a silicon nitride film formed by a C VD method may be used.
- a silicon nitride film may be formed by an oxidation process such as a plasma oxidation method.
- the first insulating film 1111 to the fifth insulating film 1115 can be formed by appropriately combining these methods.
- the second insulating film 1 1 2, the third insulating film 1 1 3, and the fourth insulating film 1 1 4 fulfilling the above are formed into a plasma using a plasma processing apparatus 100 to be described later.
- FIG. 1 A first figure.
- the plasma processing table 100 is a planar antenna with a plurality of square holes, especially RLSA (Radial 1 Line Slot Antenna), which introduces microwaves into the processing chamber.
- RLSA Ring 1 Line Slot Antenna
- it is configured as a RLSA microwave mouth wave plasma processing device that can generate a high-density, low electron temperature, mouth-wave-excited plasma by generating plasma.
- the plasma processing apparatus 100 can be suitably used for the purpose of forming a silicon nitride film with little damage by the plasma C VD method in the manufacturing process of various semiconductor devices.
- the plasma processing apparatus 100 includes, as main components, an airtight chamber 1 (processing chamber) 1, a gas supply mechanism 18 that supplies gas into the chamber 1, and a chamber 1
- An exhaust device 2 4 as an exhaust mechanism for evacuating the gas
- a microwave introduction mechanism 2 7 provided at the upper portion of the chamber 1 for introducing microwaves into the chamber 1
- a control unit 50 that controls each component of the plasma processing apparatus 100.
- the chamber 1 is formed by a substantially cylindrical container that is grounded.
- the chamber 1 may be formed of a rectangular tube-shaped container.
- the chamber 1 has a bottom wall 1 a and a side wall 1 b made of a material such as aluminum.
- the interior of the chamber 1 is provided with a mounting table 2 for horizontally supporting a silicon wafer (hereinafter simply referred to as “we 8 J”) which is an object to be processed.
- the mounting table 2 is supported by a cylindrical support member 3 that extends upward from the center of the bottom of the exhaust chamber 1 1. Is made up of ceramics such as A 1 N.
- the mounting table 2 is provided with a force bearing 4 for covering the outer edge of the mounting table 2 and guiding the weiha W.
- Force paring 4 An annular member made of materials such as quartz, A 1 N, A 1 2 O 3 , Si N, etc.
- the mounting table 2 also has a resistance heating type heat sink as a temperature control mechanism.
- the mounting table 2 is heated by being supplied with power from the heat power source 5 a, and the wafer W that is a substrate to be processed is uniformly heated by the heat.
- the mounting table 2 is provided with a thermocouple (TC) 6. By measuring the temperature with this thermocouple 6, the heating temperature of the wafer W can be controlled in the range from room temperature to 900, for example. Further, the mounting table 2 has wafer support pins (not shown) for supporting the wafer W and moving it up and down. Each wafer support pin is provided so as to protrude and retract with respect to the surface of the mounting table 2.
- a circular opening 10 is formed at a substantially central portion of the bottom wall 1 a of the chamber 1.
- the bottom wall 1 a is provided with an exhaust chamber 11 that communicates with the opening ⁇ 10 and projects downward.
- the exhaust chamber 11 is connected to an exhaust pipe 12, and is connected to the exhaust device 2 4 via the exhaust pipe 12.
- An annular gas introduction portion 14 is provided at the upper end of the side wall 1 b forming the chamber 1.
- the side wall 1 of the chamber 1 is provided with an annular gas introduction part 15, and the gas introduction parts 14 and 15 are provided in two upper and lower stages.
- And 15 are connected to a gas supply mechanism 18 for supplying a film forming source gas and a plasma excitation gas.
- the gas inlets 14 and 15 may be provided in the form of nozzles or showers.
- a loading / unloading port 16 for loading / unloading the wafer W between the plasma processing apparatus 100 and a transfer chamber (not shown) adjacent thereto is provided on the side wall 1 b of the chamber 1.
- a gate valve 17 for opening and closing the loading / unloading port 16 is provided on the side wall 1 b of the chamber 1.
- the gas supply mechanism 1 8 has, for example, a nitrogen-containing gas (N-containing gas) supply source 1 9 a, a silicon-containing gas (S i -containing gas) supply source 1 9 b, and an inert gas supply source 1 9 c. Yes.
- the nitrogen-containing gas supply source 19 a is connected to the upper gas introduction section 14.
- the silicon-containing gas supply source 19 b and the inert gas supply source 19 c are connected to the lower gas introduction unit 15.
- the gas supply mechanism 18 may have a cleaning gas supply source used for cleaning the inside of the chamber 1 as a gas supply source (not shown) other than the above, for example.
- a silicon-containing gas that is another film forming source gas for example, silane (S 1 ⁇ )
- the inert gas for example, N 2 gas or a rare gas can be used, for example, a plasma excitation gas, for example, Ar gas, K r gas, X e gas, He gas can be used, but Ar gas is preferred industrially.
- Nitrogen-containing gas is supplied from the nitrogen-containing gas supply source 19 a of the gas supply mechanism 18 through the gas line 20. 14 Introduced into chamber-1.
- the silicon-containing gas and the inert gas are supplied from the silicon-containing gas supply source 1 9 b and the inert gas supply source 1 9, respectively. Introduced into gas chamber 1 through chamber 20 The gas line 20 is provided with a mass flow controller 21 and an opening / closing valve 22 before and after the mass flow controller 21 so that the gas to be supplied can be switched and the flow rate can be controlled.
- the gas in the chamber 1 is activated by operating the exhaust device 24.
- the chamber 1 is provided with a pressure gauge (not shown) so that the pressure in the chamber 1 can be measured.
- the microwave introduction mechanism 27 includes a transmission plate 28, a flat antenna member 31, a slow wave material 3 3, a shield lid 3 4, and a waveguide 37.
- Plasma using RLSA plasma processing equipment 1 0 0 A silicon nitride film deposition process by the CVD method will be described.
- the gate valve 17 is opened, and the wafer W is loaded into the chamber 11 from the loading / unloading port 16 and mounted on the mounting table 2.
- nitrogen-containing gas and silicon-containing gas are predetermined from the nitrogen-containing gas supply source 19a and the silicon-containing gas supply source 19b of the gas supply mechanism 18 while reducing the pressure inside the chamber 1. Are introduced into the chamber 11 through the gas introduction parts 14 and 15 respectively. In this way, the inside of the chamber 1 is adjusted to a predetermined pressure.
- a microwave having a predetermined frequency, for example, 2 • 45 GHz, generated by the microwave generator 39 is transmitted through a slot-shaped microwave radiation hole 3 2 formed through the planar antenna member 3 1. Radiates into the space above the wafer W in the chamber 1 through the plate 2 8.
- the microphone mouth wave output is, for example, about 5 0 0 to 3 0 0 0 ⁇ ⁇ (0.2 5 to 1.5 4 W / cm 2 per 1 cm 2 area of the transmission plate 28) can do.
- An electromagnetic field is formed in the chamber 1 by the microwave radiated from the planar antenna member 31 to the chamber 1 through the transmission plate 2 8, and the nitrogen-containing gas and the silicon-containing gas are turned into plasma. Then, dissociation of the source gas proceeds in the plasma, and Si p H q , Si H Q , NH Q , N (where p and Q mean arbitrary numbers, and so on).
- a thin film of silicon nitride Si N is deposited by the reaction of the active species.
- the silicon nitride film is selected by selecting the conditions for plasma C VD processing when forming the silicon nitride film. ⁇ The wrap density can be controlled to a desired size.
- the trap density in the silicon nitride film to be formed is increased (for example, the trap density is in the range of 5 X 1 0 12 to 1 XI 0 13 cm- 2 eV- ')
- the plasma CVD process it is preferable to perform the plasma CVD process under the following conditions. NH 3 gas is used as the nitrogen-containing gas and Si 2 H 6 gas is used as the silicon-containing gas, and the flow rate of ⁇ ?
- 1 3 gas is within the range of 1 0 to 5 0 0 0 111 and 111 1 11 (sccm) , Preferably within the range of 100-200 mLZm in (sccm), the flow rate of Si 2 H 6 gas is 0.5-: within the range of LOO mLZ min (sccm), preferably 1-50 Set within the range of mLZm in (sccm).
- NH 3 flow ratio of gas and S i 2 H 6 gas (NH 3 gas flow rate ZS i 2 H 6 gas flow rate), from the viewpoint of forming a S i density is high silicon nitride film, 0.1 It is preferable to be within the range of ⁇ 200,000, more preferably within the range of 0.1 to 100000, and desirably within the range of 5 to 50.
- the processing pressure should be 1 to 1 3 3 3 Pa. Preferably, it is more preferably 50 to 6 ⁇ OP a.
- the trap density is within the range of 5 X 10 1 Q to 5 X 10 12 cm- 2 e V 1
- N 2 gas as the nitrogen-containing gas
- Si 2 H 6 gas as the silicon-containing gas.
- the N 2 gas flow rate is within the range of 10 to 5 0 0 0 1111 111 1 11 (sccm), preferably within the range of 1 0 0 to 2 0 0 011 1 ⁇ 111 1 11 (sccm), S i 2 H 6 Gas flow 0.5 ⁇ !
- the flow ratio of N 2 gas to S i 2 H 6 gas forms a silicon nitride film with a low Si density with a uniform film thickness. From the viewpoint, it is preferably in the range of 0.1 to 500, and more preferably in the range of 100 to 400. .
- the processing pressure is set to 0.:!-500 Pa. 1 ⁇ ! OOP a is more preferable.
- Nitrogen nitrides with different trap densities can be obtained by alternately performing plasma CVD treatment with plasma generated under the conditions for increasing the trap density and plasma generated under the conditions for decreasing trap density. Silicon films can be alternately deposited.
- the processing temperature of the plasma C V D processing is preferably such that the temperature of the mounting table 2 is 3 00: ⁇ 80, or more, preferably 4 00 to 6 0.
- the silicon nitride films constituting the second to fourth insulating films 1 1 2 to 1 1 4 can be easily manufactured.
- the silicon nitride oxide film (S i ON film) can be easily obtained by subjecting the silicon nitride film obtained as described above to, for example, plasma oxidation treatment or thermal oxidation treatment.
- a plurality of film forming apparatuses including the plasma processing apparatus 100 are connected through a vacuum without being exposed to the atmosphere, so that each film forming apparatus sequentially
- a target film (a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, or the like) can be formed.
- FIG. 4 is a cross-sectional view showing a schematic configuration of an MOS type semiconductor memory device according to the second embodiment of the present invention.
- FIG. 5 is an energy band diagram of the MOS semiconductor memory device 60 2 in FIG.
- the MOS type semiconductor memory device 60 2 of the present embodiment is laminated on a p-type silicon substrate 10 1 as a semiconductor layer and the p-type silicon substrate 1 0 1.
- the size of the band gap formed Insulating film laminate 10 2 b composed of a plurality of insulating films having different thicknesses, and gate electrode 10 3 formed on insulating film laminate 10 2 b.
- the silicon substrate 10 0 1 and the gate electrode 10 3 Between the silicon substrate 10 0 1 and the gate electrode 10 3, the first insulating film 1 2 1, the second insulating film 1 2 2, the third insulating film 1 2 3, and the fourth insulating film
- An insulating film laminated body 10 2 b having the insulating film 1 24 and the fifth insulating film 1 2 5 is provided.
- the silicon substrate 10 0 1 has a first source drain 1 0 4 consisting of an n-type diffusion layer at a predetermined depth from the surface so as to be located on both sides of the gate electrode 10 3 and A second source / drain 10 5 is formed, and a channel forming region 10 6 is formed between them.
- the MOS type semiconductor memory device 60 2 may be formed in a P type silicon layer formed in a semiconductor substrate.
- this embodiment may be implemented by a channel-channel MOS device, which will be described by taking an n-channel MS device as an example. Therefore, the contents of this embodiment described below can be applied to all n-channel MOS devices and p-channel MOS devices.
- the first insulating film 1 21, the fifth insulating film 1 2 5, and the gate electrode 10 3 are the same as those shown in FIG. 1 has the same structure as the first insulating film 1 1 1, the fifth insulating film 1 15, and the gate electrode 10 3 of the MOS type semiconductor memory device 6 0 1 according to the first embodiment. The explanation is omitted.
- the second insulating film 1 2 2 is a silicon nitride film (SiN film) formed on the first insulating film 1 2 1.
- the second insulating film 1 2 2 has an energy band gap in the range of 2.5 to 4 eV, for example.
- the film thickness of the second insulating film 12 2 is preferably, for example, in the range of 2 nm to 20 nm, more preferably in the range of 2 nm to 10 nm, and preferably in the range of 3 nm to 5 nm.
- the third insulating film 1 2 3 is a silicon nitride oxide film (S i ON film) formed on the second insulating film 1 2 2.
- This third insulating film 1 2 3 has an energy band gap in the range of 5 to 7 eV, for example.
- the thickness of the third insulating film 1 2 3 is preferably in the range of 2 nm to 30 nm, more preferably in the range of 2 nm to 15 nm, and preferably in the range of 4 nm to 10 nm. .
- the fourth insulating film 1 24 is a silicon nitride film (SiN film) formed on the third insulating film 1 2 3.
- the fourth insulating film 1 24 has the same energy band gap and film thickness as the second insulating film 1 2 2.
- the thickness of the second insulating film 1 2 2 and the fourth insulating film 1 2 4 is set so that the Coulomb blockade phenomenon occurs at the time of writing. It is preferable to set the thickness to be smaller than the thickness of the insulating film 1 2 3.
- the electron potential energy in the conduction band of the silicon substrate 10 1 is reduced in the conduction band of the second insulating film 1 2 2. It is preferable to set the electron potential energy so that it is higher than unity.
- the electron potential energy in the conduction band of the silicon substrate 10 1 is larger than the electron potential energy in the conduction band of the second insulating film 1 2 2. It is preferable to set so that it may become low. Furthermore, even when data is read out, the electron potential energy in the conduction band of the silicon substrate 10 1 is the same as that in the data holding state, and the electron potential energy in the conduction band of the second insulating film 1 2 2 is It is preferable to set it to be lower than
- the material for the film 1 2 4 is not limited to silicon nitride or silicon nitride oxide, and an insulating material such as a metal oxide can be used.
- an insulating material such as a metal oxide can be used.
- the same metal oxide as in the first embodiment can be used.
- the first insulating film 1 2 1 to the fifth insulating film 1 2 5 are formed by the thermal oxidation method, the CVD method, the ALD method, or the oxidation process by atomic diffusion as in the first embodiment. Nitride treatment can be appropriately combined to form a film.
- the second insulating film 1 2 2, the third insulating film 1 2 3, and the fourth insulating film 1 2 4, which mainly play a central role as a charge storage region It is preferable to select a film formation method using a plasma CVD method using a plasma processing apparatus 100. That is, it is preferable to form a silicon nitride film by a plasma CVD method using a plasma processing apparatus 100 or to oxidize this silicon nitride film to form a silicon nitride oxide film.
- the MOS type semiconductor memory device 60 2 includes the band gaps 1 2 1 a and 1 2 5 a of the first insulating film 1 2 1 and the fifth insulating film 1 2 5.
- a second insulating film 1 2 2 and a fourth insulating film 1 2 4 having a band gap are interposed.
- the charge is mainly near the interface between the third insulating film 1 2 3 and the second insulating film 1 2 2 and the fourth insulating film 1 2 4 having a small band gap. Is easy to accumulate.
- the energy barrier becomes larger due to the presence of the second insulating film 1 2 2 and the fourth insulating film 1 2 4, and the first insulating film 1 Charges are prevented from being extracted through the film 1 2 1 or the fifth insulating film 1 2 5. Therefore, it is possible to stably hold charges in the insulating film stack 100 b without increasing the thickness of the first insulating film 1 21 and the fifth insulating film 1 2. Yes, excellent data retention characteristics can be obtained.
- the MOS type semiconductor memory device 60 2 has improved data retention characteristics, higher write operation speed, lower power consumption, and higher reliability than the conventional MOS type semiconductor memory device. It is an excellent MOS type semiconductor memory device realized at the same time.
- the writing, reading and erasing operations of the MOS type semiconductor memory device 62 according to the present embodiment can be performed in the same manner as in the first embodiment. Further, the MOS type semiconductor memory device 60 2 can be manufactured according to the procedure described in the first embodiment.
- FIG. 6 is a cross-sectional view showing a schematic configuration of a MOS type semiconductor memory device according to the third embodiment of the present invention.
- FIG. 7 is an energy band diagram of the MO S type semiconductor memory device 60 3 in FIG.
- the MOS type semiconductor memory device 600 of the present embodiment is laminated on a p-type silicon substrate 1001 as a semiconductor layer and the p-type silicon substrate 1001.
- an insulating film stack body 10 2 c having a fourth insulating film 1 3 4 and a fifth insulating film 1 3 5 is provided.
- the silicon substrate 10 0 1 has first source drains 10 4 and 2 made of an n-type diffusion layer at a predetermined depth from the surface so as to be located on both sides of the gate electrodes 10 3.
- Source / drain 1 0 5 is formed, and a channel forming region 1 0 6 is formed between the two.
- the MOS type semiconductor memory device 63 may be formed in a P-type silicon layer formed in a semiconductor substrate.
- this embodiment may be implemented with a power S, p-channel MOS device, which is described by taking an n-channel MOS device as an example. Therefore, the contents of the present embodiment described below can be applied to all n-channel MOS devices and p-channel MOS devices.
- the first insulating film 1 31, the fifth insulating film 1 3 5, and the gate electrode 10 3 are the same as those shown in FIG.
- the configuration is the same as that of the first insulating film 1 11, the fifth insulating film 1 15, and the gate electrode 10 3 of the MOS type semiconductor memory device 6 0 1 according to the present embodiment. Is omitted.
- the second insulating film 1 3 2 is a silicon nitride oxide film (S i 0 N film) formed on the first insulating film 1 3 1.
- the second insulating film 13 2 has an energy band gap in the range of 5 to 7 eV, for example.
- the thickness of the second insulating film 13 2 is preferably in the range of 2 nm to 20 nm, more preferably in the range of 2 nm to 10 nm, and preferably in the range of 3 nm to 5 nm.
- the third insulating film 1 3 3 is a silicon nitride film (SiN film) formed on the second insulating film 1 3 2.
- This third insulating film 1 3 3 has an energy band gap in the range of, for example, 2.5 to 4 eV as an average of the entire film.
- the film thickness of the third insulating film 1 3 3 is preferably in the range of 2 nm to 30 nm, for example, more preferably in the range of 2 nm to l 5 nm, and in the range of 4 nm to; LO nm. Is desirable.
- the composition ratio of nitrogen is changed in the thickness direction of the film from the silicon substrate 10 1 toward the gate electrode 10 3. That is, the third insulating film 1 3 3 has a small nitrogen composition ratio in the vicinity of the interface with the second insulating film 1 3 2, and a relatively large nitrogen composition ratio once in the center of the film than in the vicinity of the interface. Thus, it has a nitrogen concentration profile that again changes to a small nitrogen composition ratio near the interface with the fourth insulating film 1 3 4.
- Such control of the nitrogen concentration in the film is performed during the CVD film formation of the silicon nitride film to be the third insulating film 1 3 3 using the plasma processing apparatus 100 shown in FIG. This is possible by changing the raw material gas composition and pressure.
- Fourth insulating film 1 34 is a silicon nitride oxide film (SiN film) formed on the third insulating film 1 3 3.
- the fourth insulating film 1 3 4 has the same energy band gap and film thickness as the second insulating film 1 3 2.
- the material of the second insulating film 1 3 2, the third insulating film 1 3 3, and the fourth insulating film 1 3 4 is not limited to silicon nitride and silicon nitride oxide, but may be an insulating material such as a metal oxide. Can be used. Here, the same metal oxide as in the first embodiment can be used.
- the first insulating film 1 3 1 to the fifth insulating film 1 3 5 are formed by the thermal oxidation method, the CVD method, the ALD method, or the oxidation process by atomic diffusion as in the first embodiment. Nitride treatment can be appropriately combined to form a film.
- the second insulating film 1 3 2, the third insulating film 1 3 3, and the fourth insulating film 1 3 4 that mainly serve as charge storage regions are provided. It is preferable to select a method for forming a film using a plasma CVD method using a plasma processing apparatus 10 0. That is, it is preferable to form a silicon nitride film by a plasma CVD method using a plasma processing apparatus 100 or to oxidize the silicon nitride film to form a silicon nitride oxide film.
- the MOS type semiconductor memory device 60 3 includes the band gaps 1 3 1 a and 1 3 5 a of the first insulating film 1 3 1 and the fifth insulating film 1 3 5.
- an intermediate size band gap 1 3 A second insulating film 1 3 2 and a fourth insulating film 1 3 4 having 2 a and 1 3 4 a are interposed. Furthermore, the third insulating film 1 3 3 has a node gap 1 3 3 a that is small in the center of the film in the thickness direction, and both ends of the film (that is, the second insulating film) It has a band structure that changes so as to increase in the vicinity of the interface between the film 1 3 2 and the fourth insulating film 1 3 4.
- Insulating film Laminate 1 0 2 c Write voltage required to inject charge into Can be used.
- the size of the band gap of the first to fifth insulating films 1 31 1 to 1 35 can be controlled by the elements constituting the film and the composition ratio thereof.
- the film thicknesses of the second insulating film 13 2 and the fourth insulating film 1 3 4 are set to the Coulomb mouth clogging phenomenon at the time of writing. It is preferable to set the thickness to be smaller than the thickness of the third insulating film 1 3 3 so that this occurs. Furthermore, for the purpose of increasing the probability of occurrence of tunneling and further improving the writing speed, the electron potential energy in the conduction band of the silicon substrate 10 1 is determined by the second insulating film 1 3 2. It is preferable to set it to be higher than the electron potential energy in the conduction band.
- the electron potential energy in the conduction band of the silicon substrate 10 1 becomes the electron potential energy in the conduction band of the second insulating film 1 3 2. It is preferable to set so as to be lower than that. In addition, when reading data, the electron potential energy in the conduction band of the silicon substrate 10 0 1 is compared with the electron potential energy in the conduction band of the second insulating film 1 3 2 as in the data holding state. It is preferable to set it to be low.
- the insulating film stacked body 102c charge is easily accumulated mainly in a region centering on the third insulating film 1333 having the smallest band gap.
- this embodiment by changing the composition ratio in the film thickness direction in the film of the third insulating film 1 3 3, many lattice gaps exist in the film. There is a dangling bond. As a result, a large number of traps (charge trapping centers) for trapping charges are formed in the third insulating film 1 3 3, so that the charge storage capability can be increased.
- the MOS type semiconductor memory device 600 has improved data retention characteristics, higher write operation speed, lower power consumption, and higher reliability than the conventional MOS type semiconductor memory device. It is an excellent MOS type semiconductor memory device realized at the same time.
- the writing, reading and erasing operations of the MOS type semiconductor memory device 63 according to this embodiment can be performed in the same manner as in the first embodiment. Further, the MOS type semiconductor memory device 60 3 can be manufactured according to the procedure described in the first embodiment.
- FIG. 8 is a cross-sectional view showing a schematic configuration of a MOS type semiconductor memory device according to the fourth embodiment of the present invention.
- FIG. 9 is an energy band diagram of the MO S type semiconductor memory device 60 4 in FIG.
- the MOS type semiconductor memory device 60 4 of the present embodiment has a p-type silicon substrate 1001 as a semiconductor layer and is stacked on the p-type silicon substrate 1001.
- the formed insulating film laminate 10 2 d composed of a plurality of insulating films having different band gap sizes, and the gate electrode 10 formed on the insulating film laminate 10 0 2 d 3 and.
- a layer body 1 0 2 d is provided.
- the silicon substrate 10 0 1 has first source drains 10 4 and 2 made of n-type diffusion layers at a predetermined depth from the surface so as to be located on both sides of the gate electrodes 10 3. Source drains 1 0 5 are formed, and a channel forming region 1 0 6 is formed between the two.
- the MOS type semiconductor memory device 604 may be formed in a P-well or P-type silicon layer formed in the semiconductor substrate.
- this embodiment may be implemented by a force p-channel MOS device that will be described by taking an n-channel MOS device as an example. Therefore, the contents of this embodiment described below can be applied to all n-channel MOS devices and p-channel MOS devices.
- the first insulating film 14 1, the fifth insulating film 14 45 and the gate electrode 10 3 are the same as those shown in FIG.
- the configuration is the same as that of the first insulating film 1 11, the fifth insulating film 1 15, and the gate electrode 10 3 of the MOS type semiconductor memory device 6 0 1 according to the present embodiment. Is omitted.
- the second insulating film 14 2 is a silicon nitride film (SiN film) formed on the first insulating film 14 1.
- the second insulating film 14 2 has an energy band gap in the range of 2.5 to 4 eV, for example.
- the thickness of the second insulating film 14 2 is preferably in the range of 2 nm to 20 nm, more preferably in the range of 2 nm to 10 nm, and desirably in the range of 3 nm to 5 nm.
- the third insulating film 14 3 is a silicon nitride oxide film (Si ON film) formed on the second insulating film 14 2.
- the third insulating film 14 3 has an energy band gap in the range of, for example, 5 to 7 eV as an average of the entire film.
- the film thickness of the third insulating film 14 3 is preferably in the range of 2 nm to 30 nm, for example, and more preferably in the range of 2 nm to 15 nm. Preferably, it is within the range of 4 nm to 10 nm.
- the third insulating film 14 3 changes the composition ratio of oxygen in the thickness direction of the film from the silicon substrate 101 to the gate electrode 103.
- the third insulating film 14 3 has a small oxygen composition ratio with respect to nitrogen in the film near the interface with the second insulating film 14 2, and a large oxygen composition ratio once in the center of the film.
- it has a profile that changes again to a small oxygen composition ratio in the vicinity of the interface with the fourth insulating film 1 4 4.
- Such oxygen concentration in the film can be controlled, for example, by changing conditions such as the composition and pressure of the oxygen gas during the plasma oxidation treatment of the silicon nitride film.
- the fourth insulating film 144 is a silicon nitride film (SiN film) formed on the third insulating film 14 3.
- the fourth insulating film 144 has the same energy band gap and film thickness as the second insulating film 144.
- the material of the second insulating film 1 4 2, the third insulating film 1 4 3, and the fourth insulating film 1 4 4 is not limited to silicon nitride and silicon nitride oxide, but may be an insulating material such as a metal oxide. Can be used. As the metal oxide, the same metal oxide as in the first embodiment can be used.
- the first insulating film 14 1 to the fifth insulating film 14 45 are formed by a thermal oxidation method, a CVD method, or an oxidization treatment by atomic diffusion, a nitridation treatment, as in the first embodiment.
- a film can be formed by appropriately combining the above.
- the second insulating film 14 2, the third insulating film 14 3, and the fourth insulating film 14 4, which mainly play a central role as a charge storage region It is preferable to select a film formation method using a plasma C VD method using the processing apparatus 1 0 0.
- a silicon nitride film is formed by a plasma C VD method using a plasma processing apparatus 100, or the silicon nitride film is oxidized to form silicon nitride oxide.
- a film is preferred.
- the MOS type semiconductor memory device 60 4 has the band gap of the first insulating film 14 1 and the fifth insulating film 1 4 5 1 4 1 a and 1 4 5 a force.
- the second insulating film 14 2 and the fourth insulating film 14 4 having the smallest band gap are interposed. Further, in the third insulating film 14 3, the band gap in the film thickness direction is small near the interface with the second insulating film 1 4 2, and once increases at the center of the film, It has a profile that changes so as to decrease again near the interface with the fourth insulating film 1 4 4.
- the size of the band gap of the first to fifth insulating films 14 1 to 1 4 45 can be controlled by the elements constituting the film and the composition ratio thereof.
- the thickness of the second insulating film 14 2 and the fourth insulating film 14 4 is set so that the Coulomb blockade phenomenon occurs at the time of writing. It is preferable to set the thickness to be thinner than the thickness of the insulating film 1 4 3. Furthermore, the electron potential energy in the conduction band of the silicon substrate 10 0 1 is increased for the purpose of increasing the probability of occurrence of tunneling and further improving the writing speed. It is preferable to set the second insulating film 14 2 to be higher than the electron potential energy 1 in the conduction band.
- the electron potential energy in the conduction band of the silicon substrate 10 1 is lower than the electron potential energy in the conduction band of the second insulating film 1 4 2 during data retention. It is preferable to set so that In addition, when reading data, the electron potential energy in the conduction band of the silicon substrate 10 1 becomes the electron potential energy 3 in the conduction band of the second insulating film 14 2, as in the case of data holding. Set to be lower than
- the insulating film stack 10 0 2 d mainly the vicinity of the interface between the third insulating film 1 4 3 and the second insulating film 1 4 2 and the fourth insulating film 1 4 4 having a small band gap. Charges are likely to accumulate.
- this embodiment by changing the composition ratio of oxygen atoms to nitrogen atoms in the film thickness direction in the third insulating film 14 3, many lattice gaps are formed in the film. There will be many dangling bonds. As a result, a large number of traps (charge trapping centers) for trapping charges are formed in the third insulating film 14 3, so that the charge storage capability can be increased.
- the MOS type semiconductor memory device 604 has a conventional MOS type semiconductor memory device. Compared to conductor memory devices, this is an excellent semiconductor memory device that has improved data retention characteristics, increased write operation speed, reduced power consumption, and improved reliability.
- the writing, reading and erasing operations of the MOS type semiconductor memory device 60 4 according to the present embodiment can be performed in the same manner as in the first embodiment.
- the MOS type semiconductor memory device 60 4 can be manufactured according to the procedure described in the first embodiment.
- FIG. 10 is a cross-sectional view showing a schematic configuration of a MOS type semiconductor memory device according to a fifth embodiment of the present invention.
- FIG. 11 is an energy band diagram of the MOS type semiconductor memory device 60 5 in FIG.
- the MOS type semiconductor memory device 60 5 of this embodiment includes a p-type silicon substrate 10 0 1 as a semiconductor layer, and the p-type silicon substrate 1 0 1.
- An insulating film laminate 10 0 2 e formed of a plurality of insulating films with different band gaps formed thereon, and a gate electrode 1 formed on the insulating film laminate 1 0 2 e 0 3 and have.
- An insulating film laminated body 10 0 2 e is provided between the silicon substrate 10 1 and the gate electrode 10 3, and this insulating film laminated body 1 0 2 e is the first insulating film 1 5 1, 2nd insulation film 1 5 2, 3rd insulation film 1 5 3, 4th insulation film 1 5 4, 5th insulation film 1 5 5, Spacer insulation And a membrane 1 5 6.
- the three-layered laminate of the second insulating film 15 2, the third insulating film 15 3 and the fourth insulating film 15 4 is a unit. Three units are stacked repeatedly through a single insulating film 1 5 6.
- the silicon substrate 10 0 1 has a first source drain 1 0 made of an n-type diffusion layer at a predetermined depth from the surface so as to be located on both sides of the gate electrode 10 3. 4 and second source 'drain 1 0 5 formed
- the channel forming region 10 6 is between the two.
- this embodiment will be described by taking an n-channel MOS device as an example, it may be implemented by a p-channel MOS device. Therefore, the contents of this embodiment described below can be applied to all n-channel MOS devices and p-channel MOS devices.
- the first insulating film 15 1, the fifth insulating film 15 5, and the gate electrode 10 3 are the same as those shown in FIG. Since it has the same configuration as the first insulating film 1 1 1, the fifth insulating film 1 1 5 and the gate electrode 1 0 3 of the M0 S type semiconductor memory device 6 0 1 according to the embodiment, Description is omitted.
- the second insulating film 1 5 2 is a silicon nitride film (SiN film) formed on the insulating film 1 5 1 of this 1.
- the second insulating film 1 5 2 is, for example, 2
- the thickness of the second insulating film 15 2 is preferably in the range of 2 nm to 20 nm, more preferably in the range of 2 nm to 10 nm, and in the range of 3 nm to 5 nm.
- the third insulating film 15 3 is a silicon nitride oxide film (SiN film) formed on the second insulating film 15 2.
- This third insulating film 15 3 3 is, for example, Has an energy band cap in the range of 5-7 eV
- the film thickness of the third insulating film 15 3 is preferably, for example, in the range of 2 ⁇ m to 30 nm, more preferably in the range of 2 nm 15 nm, and 4 nm to 3 nm.
- a range of 10 nm is desirable.
- the fourth insulating film 15 4 is a silicon nitride film (SiN film) formed on the third insulating film 15 3.
- the fourth insulating film 15 4 is the second insulating film. It has the same energy, membrane and film thickness as membrane 1 5 2.
- Spacer insulating film 1 5 6 is formed on fourth insulating film 1 5 4 This is a silicon nitride oxide film (S i ON film).
- S i ON film silicon nitride oxide film
- the spacer insulating film 15 6 a film similar to the third insulating film 15 3 can be used. That is, the spacer insulating film 15 6 has an energy band gap within a range of 5 to 7 eV, for example.
- the thickness of the spacer insulating film 15 6 is preferably in the range of 2 nm to 30 nm, for example, and more preferably in the range of 2 nm to l 5 nm.
- a range of 4 nm to 10 nm is desirable.
- Second insulating film 1 5 2 Third insulating film 1 5 3, fourth insulating film 1
- the material of the 5 4 and the spacer insulating film 1 5 6 is not limited to a silicon nitride film or a silicon nitride oxide film, and an insulating material such as a metal oxide can be used.
- a metal oxide the same metal oxide as in the first embodiment can be used.
- the first insulating film 15 1 to the fifth insulating film 15 5 5 and the spacer-insulating film 1 56 are formed in the same manner as in the first embodiment by thermal oxidation or C A film can be formed by appropriately combining the VD method, oxidation treatment by atomic diffusion or nitridation treatment.
- the second insulating film 15 2, the third insulating film 15 3, and the fourth insulating film 15 4 that mainly play a central role as a charge storage region are formed by plasma. It is preferable to select a film formation method using a plasma C VD method using a processing apparatus 100. That is, it is preferable to form a silicon nitride film by a plasma C VD method using a plasma processing apparatus 100 or to oxidize this silicon nitride film to form a silicon nitride oxide film.
- the MOS type semiconductor memory device 60 5 includes the band gaps 1 5 1 a and 1 5 of the first insulating film 15 1 and the fifth insulating film 1 5 5.
- Band gap 1 5 2 a, 1 5 Compared to 3 a, 1 5 4 a and 1 5 6 a, it has a large energy band structure.
- the second insulating film 15 2 and the fourth insulating film 15 4 having the smallest band gap are interposed at the positions in contact with the first insulating film 15 1 and the fifth insulating film 1 5 5. ing.
- the size of the band gap of the first to fifth insulating films 1 ⁇ 1 to 1 55 and the spacer insulating film 1 56 is determined by the elements constituting the film and the composition ratio thereof. It can be controlled by.
- the thickness of the second insulating film 15 2 and the fourth insulating film 15 4 is set so that the Coulomb blockade phenomenon occurs at the time of writing. It is preferable to set the thickness to be smaller than the thickness of the insulating film 15 3. Furthermore, for the purpose of increasing the probability of occurrence of tunneling and further improving the writing speed, the electron potential energy in the conduction band of the silicon substrate 10 1 becomes the conduction band of the second insulating film 15 2. It is preferable to set it so that it is higher than the electron potential energy at.
- the electron potential energy in the conduction band of the silicon substrate 10 1 is larger than the electron potential energy in the conduction band of the second insulating film 15 2. It is preferable to set so that it may become low. Furthermore, when reading data, the electron potential energy in the conduction band of the silicon substrate 101 is lower than the electron potential energy in the conduction band of the second insulating film 15 2, as in the data holding state. To be It is preferable to set to.
- the MOS type semiconductor memory device 605 has improved data retention characteristics, higher write operation speed, lower power consumption, and higher reliability than the conventional MOS type semiconductor memory device. It is an excellent semiconductor memory device realized at the same time.
- the second insulating film 15 2, the third insulating film 15 3, and the fourth insulating film 15 4 are stacked as a unit, and 3 units are repeatedly stacked.
- the number of repetitions may be 2 units or 4 units or more.
- the stacked body of the second insulating film 15 2, the third insulating film 15 3 and the fourth insulating film 15 4 is interposed via the spacer insulating film 1 5 6. Although repeated lamination was performed, the spacer insulating film 15 6 need not be provided.
- the third insulating film 1 5 3 is changed by changing the composition ratio of nitrogen to silicon or the composition ratio of oxygen to nitrogen in the film thickness direction. 5 3 can be configured in the same manner as the band gap structure shown in the third embodiment or the fourth embodiment.
- the second insulating film 15 2 is replaced with a silicon nitride oxide film (S i 0 N film) and a third insulating film 15 3. Silicon nitride film (SiN film), fourth insulating film 1554 as silicon nitride oxide film (SiON film), and spacer insulating film 1556 as silicon nitride film (SiN film) Also good.
- FIG. 12 An example of the energy band structure in this case is shown in Fig. 12.
- charges are likely to be accumulated mainly in the region centering on the third insulating film 15 3, and the thickness of the first insulating film 15 1 and the fifth insulating film 15 5 is increased.
- the writing, reading and erasing operations of the MOS type semiconductor memory device 604 according to the present embodiment can be performed in the same manner as in the first embodiment. Further, the MOS type semiconductor memory device 60 4 can be manufactured according to the procedure described in the first embodiment.
- FIG. 13 is a cross-sectional view showing a schematic configuration of a MOS type semiconductor memory device according to a sixth embodiment of the present invention.
- the MOS type semiconductor memory device 60 6 of this embodiment includes a p-type silicon substrate 10 0 1 as a semiconductor layer, and the p-type silicon substrate 10 0. Insulating film 1 61 formed on 1, first gate electrode 1 6 2 formed on this insulating film 1 6 1, and laminated on this first gate electrode 1 6 2 Formed on the insulating film laminate 1 0 2 f and the insulating film laminate 1 0 2 ⁇ , each having a plurality of insulating films having different band gap sizes.
- the silicon substrate 10 1 is provided with a first source, a drain 10 4 and a second n-type diffusion layer at a predetermined depth from the surface so as to be located on both sides of the gate electrode 16 3.
- Source / drain 1 0 5 is formed, and a channel forming region 1 0 6 is formed between the two.
- the MOS type semiconductor memory device 60 1 may be formed in a p-well or p-type silicon layer formed in the semiconductor substrate.
- this embodiment may be implemented with a power S, p-channel MOS device, which will be described by taking an n-channel MOS device as an example. Accordingly, the contents of the present embodiment described below can be applied to all n-channel MOS devices and p-channel MOS devices.
- the insulating film 16 1 is the first of the MOS type semiconductor memory device 6 0 1 according to the first embodiment shown in FIG.
- the first gate electrode 16 2 and the second gate electrode 1 63 in the MOS type semiconductor memory device 60 6 are the same as those in the first implementation. Since the configuration is the same as that of the gate electrode 10 3 of the MOS type semiconductor memory device 60 1 according to the embodiment, description thereof is omitted.
- any one of the first to fifth embodiments described above may be used as the insulating film laminate 10 2 f between the first gate electrode 16 2 and the second gate electrode 16 3.
- a structure having the same structure as that of the described insulating film laminates 10 2 a to 10 2 e can be used.
- the individual insulating films constituting the insulating film stack 10 2 f are not shown.
- the MOS type semiconductor memory in the MS type semiconductor memory devices 60 1 to 60 5 (FIG. 1, FIG. 4, FIG. 6, FIG. 8 and FIG. 10) according to the first to fifth embodiments, as the semiconductor layer, the MOS type semiconductor memory according to the present embodiment In the device 6 06, data rewriting is performed by transferring charges between the first gate electrode 16 2 and the second gate electrode 16 3 formed on the insulating film 16 1. It can be performed.
- the first source drain 10 4 and the second source drain 1 0 5 are held at 0 V with respect to the potential of the silicon substrate 10 1, and the first gate The gate electrode 16 2 is floating and a predetermined positive voltage is applied to the second gate electrode 16 3. At this time, electrons are accumulated in the channel formation region 106 and an inversion layer is formed, and a part of the charge in the inversion layer is insulated by the tunnel phenomenon and the first gate electrode 16 2 It moves to the insulating film laminated body 1 0 2 f via.
- the first source / drain 1 0 4, the second source / drain 1 0 5, and the first gate electrode 1 6 with respect to the potential of the silicon substrate 10 1 2 is held at 0 V, and a predetermined positive voltage is applied to the second gate electrode 16 3, so that a part of the charge is transferred from the first gate electrode 1 6 2 to the insulating film laminate 1 0 You may move it to 2 f. Then, the electrons that have moved to the insulating film stack 10 2 f are trapped by the charge trapping centers formed therein, and data is accumulated. At this time, in the conventional device, it was necessary to inject the charge through a thick insulating film, which caused problems such as a high write voltage and a slow write speed (see Fig.
- the electron potential energy in the conduction band of the silicon substrate 10 1 is changed to the second insulating film (for example, the second insulating film 1 1 2, 1 2 2, 1 3 2 , 1 4 2, 1 5 2), it is possible to inject charge through a thin insulating film by setting it higher than the electron potential energy in the conduction band (Fig. 14 (d) See). So with the device according to the invention Can reduce the writing voltage and increase the writing speed.
- the second insulating film for example, the second insulating film 1 1 2, 1 2 2, 1 3 2 , 1 4 2, 1 5 2
- the electron potential energy in the conduction band of the silicon substrate 101 becomes the second insulating film (for example, the second insulating film 1 1 2, 1 2 2, 1 3 2, 1 4 2, 1 5 2) It is possible to reduce the effective average barrier barrier through a thick insulating film by setting it to be lower than the electron potential energy in the conduction band. (See Fig. 14 (f)). Therefore, in the device according to the present invention, the read voltage can be reduced, and the read speed can be increased. .
- a voltage of 0 V is applied to both the first source and drain 1 0 4 and the second source and drain 1 0 5 with respect to the potential of the silicon substrate 1, and the first gate electrode 1 6 2 is floating, and a negative voltage of a predetermined magnitude is applied to the second gate electrode 1 6 3.
- a voltage of 0 V is applied to both the first source and drain 1 0 4 and the second source and drain 1 0 5 with respect to the potential of the silicon substrate 1, and the first gate electrode 1 6 2 is floating, and a negative voltage of a predetermined magnitude is applied to the second gate electrode 1 6 3.
- the first source 'drain 1 0 4, second source' drain 1 0 5 and the first gate with respect to the potential of the silicon substrate 10 1
- the electrode 1 62 By holding the electrode 1 62 at 0 V and applying a predetermined negative voltage to the second gate electrode 1 6 3, the electrons held in the insulating film stack 1 0 2 f are insulated.
- the film may be extracted into the channel formation region 106 of the silicon substrate 101 through the film 16 1.
- problems such as a large erase voltage and a slow erase speed have occurred (see Fig. 14 (b)).
- the electron potential energy in the conduction band of the silicon substrate 10 0 1 becomes the second insulating film (for example, the second insulating film 1 1 2, 1 2 2, 1 3 2, 1 4 2, 1 5 2) is set to be higher than the electron potential energy in the conduction band, it is possible to discharge charges through a thin insulating film (Fig. 14). (See e).) Therefore, in the device according to the present invention, the erase voltage can be reduced and the erase speed can be increased.
- the method of writing, reading, and erasing information in the MOS type semiconductor memory device 60 6 is not limited, and writing, reading, and erasing may be performed by a method different from the above.
- the first source 'drain 10 4 and the second source' drain 1 0 5 are not fixed, but function as alternate sources or drains, so that each memory cell has 2 bits. The capacity can be increased by enabling writing and reading of the above information.
- the MOS type semiconductor memory device 60 6 according to the present embodiment includes the first to Similar to the MOS type semiconductor memory device 6 0 1 to 6 0 ⁇ according to the fifth embodiment, compared with the conventional MOS type semiconductor memory device, the data retention characteristics are improved and the write operation speed is increased. It is an excellent MOS type semiconductor memory device that achieves low power consumption and improved reliability at the same time. Note that the MOS type semiconductor memory device 60 6 according to the present embodiment can be manufactured according to the procedure described in the first embodiment.
- the present invention can be used with various modifications within a range in which the threshold value of the memory cell changes due to the charge existing in the insulating film.
- information can be written, read, and erased using physical phenomena such as the F ⁇ tunnel phenomenon, hot electron injection phenomenon, hot hole injection phenomenon, and photoelectric effect.
- FIGS. 14 (a) to (c) schematically show energy diagrams in writing, erasing, and data holding states of a conventional MOS type semiconductor memory device.
- FIGS. 4D to 5F schematically show energy diagrams at the time of writing, erasing and holding data in the MOS type semiconductor memory device of the present invention.
- the electric charge is held in a certain distribution between the first insulating film and the fifth insulating film. Since the region centered in the third insulating film or near the interface is the portion that is responsible for charge accumulation, this portion is expressed as the “charge accumulation region” in FIG. 14 for convenience of explanation. .
- the probability of electrons moving between the silicon substrate and the charge storage region is inversely proportional to the size of the energy barrier EB (that is, the height H and width T of the energy barrier EB). Increase the band gap of the first insulating film Then, since the height H of the energy barrier EB increases, the movement of electrons between the silicon substrate side and the charge storage layer side is limited. In addition, when the thickness of the first insulating film is increased, since the width T is increased, the energy barrier EB is also increased. In this way, increasing the thickness of the first insulating film is effective in preventing electrons held on the charge storage region side from flowing out to the silicon substrate side through the first insulating film. Method.
- the band gap of the first insulating film is increased and the film thickness is increased, as shown in FIG. 14 (c).
- the height H and width T of the energy barrier EB by the first insulating film can be increased.
- the thickness of the first insulating film is increased, for example, electrons are less likely to be injected from the silicon substrate into the charge storage region due to the tunnel effect during writing. As shown in), a large write voltage must be applied during writing. Also during erasing, a large erasing voltage is required as shown in Fig. 5 (b).
- the band gap of the first insulator ⁇ should be reduced and the film thickness should be reduced.
- the energy barrier EB will also be reduced, and the data retention characteristics will be reduced. Resulting in.
- the first insulating film and the fifth insulating film having a large band gap are adjacent to each other, and are smaller than these.
- Second and fourth insulating films having a band gap were provided.
- the energy barrier EB width when electrons pass from the charge storage region side to the silicon substrate side can be T 1, and even with a low erasing voltage, The move is smooth.
- FIG. 14 (f) not only the first insulating film (fifth insulating film) but also the second insulating film (fifth insulating film) in a state where electrons are held in the charge storage region.
- the width T becomes large because it becomes an energy barrier EB, and even if the thickness of the first insulating film (fifth insulating film) is not increased, charges can be transferred from the charge storage region. It is prevented from slipping out and excellent charge retention characteristics are obtained.
- the size of the band gap is controlled by changing the material of the insulating film.
- the band gap of the silicon nitride film to be formed is selected by selecting the conditions of the plasma CVD process when forming the silicon nitride film, particularly the pressure condition. Can be controlled to a desired size. This will be explained based on experimental data. FIGS.
- FIG. 15 and 16 show the relationship between the band gap of the silicon nitride film and the processing pressure when plasma CVD is performed by the plasma processing apparatus 100 and a single silicon nitride film is formed.
- Figure 15 shows the results when NH 3 gas is used as the nitrogen-containing gas and Si 2 H 6 gas is used as the silicon-containing gas.
- Figure 16 shows the results when N 2 gas and silicon-containing gas are used as the nitrogen-containing gas. When using Si 2 H 6 gas as It is a result.
- the plasma CVD conditions are as follows.
- the band gap of the silicon nitride film is a thin film property measuring device n & k A na 1 yzer (trade name; n & k technology) Measured by a single company).
- the processing pressure is within the range of 1 3.3 Pa to 1 3 3.3 Pa.
- the band gap of the formed silicon nitride film changed within the range of about 5.1 eV to 5.8 eV. That is, a silicon nitride film having a desired band gap can be easily formed by changing only the processing pressure while keeping the Si 2 H 6 flow rate constant.
- the processing pressure is mainly controlled and if necessary S i 2 H 6 flow rate can be controlled as a slave.
- the flow rate of S 1 2 H 6 is preferably in the range of 3 mL / min (sccm) to 40 mLZm in (sccm), and 3 mL / min (sccm) to 20 mL / in (sccm).
- the following range is more preferable.
- the NH 3 flow rate is preferably within the range of 50 mLZm in (sccm) to l OOO mL Zm in (sccm), preferably within the range of 50 mL / min (sccm) to 50 O mL Zm in (sccm). Is more preferred.
- the flow ratio (S i 2 H 6 ZNH 3 ) between S i 2 H 6 gas and NH 3 gas is preferably in the range of 0.0 15 to 0.2, It is more preferably within the range of 0.1 or less.
- plasma C VD using N 2 Si 2 H 6 film forming source gas has a processing pressure in the range of 2.7 Pa to 6 6.7 Pa.
- the band gap of the formed silicon nitride film changed within the range of about 4.9 eV to 5.8 eV.
- the band gap size can also be changed by changing the flow rate of the Si 2 H 6 gas. did it.
- the flow rate ratio (S i 2 H 6 / N 2 ) between S i 2 H 6 gas and N 2 gas is preferably in the range of 0.0 1 or more and 0.2 or less. A range of 1 or more and 0.1 or less is more preferable.
- a silicon nitride film having a band gap of 4.9 eV or more can be formed by controlling the processing pressure and the flow rate ratio of the source gas.
- the silicon nitride film was formed by LPC VD with the processing pressure varied in the same way, but the band gap varied between 4.9 eV and 5 eV and 0.leV. It was difficult to control the band gap with LPCVD.
- the plasma C VD using the plasma processing apparatus 100 In processing, the main factor that determines the size of the band gap to be deposited is the processing pressure. Therefore, using the plasma processing apparatus 1 0 0
- the treatment pressure within the range of 1 to 1 3 3 3 Pa It is preferable to set it within the range of 1 to 1 3 3 Pa.
- the flow rate ratio of NH 3 gas to the total gas flow rate is in the range of 10 to 99.99%, preferably in the range of 90 to 99.99%.
- the flow rate ratio of 2 H 6 gas is in the range of 0.01 to 90%, preferably in the range of 0.:! To 10%.
- the flow ratio of Si 2 H 6 gas to NH 3 gas increases the amount of charge trapping of the silicon nitride film, From the viewpoint of increasing the erasing speed and enhancing the charge retention performance, it is preferably within the range of 0.015 to 0.2.
- the range of the flow rate of rare gas is 2 0 ⁇ 2 0 0 0 m L / min (sccm), preferably 2 0 ⁇ : L 0 OO mL Zm in the range of in (sccm), the flow rate of NH 3 gas Within the range of 2 0 to 3 0 00 mL Zm in (sccm), preferably within the range of 2 0 to 10 0 OmL Zm in (sccm), the flow rate of the Si 2 H 6 gas is 0.:! Within the range of 50 mL / min (sccm), preferably 0.5 to: within the range of LO mL / min (sccm), the above flow rate ratio Can be set to be
- the processing pressure should be in the range of 1 to 1 3 3 3 Pa It is preferable :! More preferably, it is in the range of ⁇ 1 3 3 Pa.
- the flow rate ratio of N 2 gas to the total gas flow rate is in the range of 10 to 99.99%, preferably in the range of 90 to 99.99%.
- the flow rate ratio of the Si 2 H 6 gas with respect to is in the range of 0.01 to 90%, preferably in the range of 0.01 to: 10%.
- flow ratio of S i 2 H 6 gas and N 2 gas's is to increase the trapped amount of the charge of the silicon nitride film, the writing speed and erase speed From the standpoint of speeding up the process and improving the charge retention performance, it is preferably within the range of 0.01 to 0.2.
- the range of the flow rate of rare gas is 2 0 ⁇ 3 0 0 0 mL / min (sccm), preferably in the range of 2 0 ⁇ 1 0 0 0 m L / min (sccm), the N 2 gas flow rate Within the range of 5 0 to 3 0 0 0 m L / min (sccm), preferably within the range of 2 0 0 to 1 5 0 0 m L / min (sccm), the flow rate of Si 2 H 6 gas is 0.
- the flow rate can be set within the range of 1 to 50 mL Zm in (sccm), preferably within the range of 0.5 to 5 mL / min (sccm).
- the treatment pressure should be:! Preferably within the range of ⁇ 1 3 3 3 Pa, 1 ⁇ 1 3 3 More preferably, it is within the range of Pa.
- S i 2 within this range all gas to the flow rate of NH 3 gas flow rate ratio of 1 0-9 9.9 9% for, for preferably in the range of 9 0-9 9.9% and the total gas flow rate
- the flow rate ratio of H 6 gas is in the range of 0.001 to 10%, preferably in the range of 0.01 to; 10%.
- the flow ratio of Si 2 H 6 gas to NH 3 gas increases the trapping amount of charge in the silicon nitride film, and the writing speed and erasing speed From the standpoint of speeding up the process and increasing the charge retention performance, it is preferably within the range of 0.015 to 0.2.
- the range of the flow rate of rare gas is 2 0 ⁇ 2 OOO mL / min ( sccm), preferably in the range of 2 0 0 ⁇ 1 0 0 0 m L / in (sccm), the flow rate of NH 3 gas is 2 0 ⁇ !
- the flow rate of Si 2 H 6 gas is 0.5--50 mL Zm in (sccm ), Preferably
- the flow rate ratio can be set to the above.
- the treatment pressure within the range of 1 to 1 3 3 3 Pa. It is preferable :! More preferably, it is in the range of ⁇ 1 3 3 Pa.
- the flow rate ratio of N 2 gas to the total gas flow rate is within the range of 10 to 99.99%, preferably within the range of 90 to 99.9%.
- the flow rate ratio of the Si 2 H 6 gas is in the range of 0.01 to 90%, preferably in the range of 0.1 to 10%.
- the flow rate ratio between Si 2 H 6 gas and N 2 gas increases the charge trap amount of the silicon nitride film, writing speed and erasing speed In the range of 0.0 1 to 0.2 from the viewpoint of speeding up the process and increasing the charge retention performance.
- the flow rate of rare gas is within the range of 20 to 3 00 00 mL / min (sccm), preferably within the range of 2 00 to 10 00 mL / in (sccm), and the flow rate of N 2 gas is Within the range of 2 0 to 3 0 0 0 m L / min (sccm), preferably within the range of 2 0 0 to 2 0 0 0 mLZm in (sccm), the flow rate of Si 2 H 6 gas is 0.5 to The flow rate can be set within the range of 50 mLZm in (sccm), preferably within the range of 0.5 to 10 mL / min (sccm).
- the processing temperature of the plasma CVD process is preferably set to a temperature of the mounting table 2 of 300 ° C. to 800 ° C. or more, preferably 4 00 to 600 °. .
- silicon nitride films with different band gaps are alternately deposited. be able to.
- the bandgap size can be easily controlled only by the processing pressure, continuous deposition is possible when forming a stack of silicon nitride films with different bandgap, thereby improving process efficiency. It is extremely advantageous for improvement.
- the band gap of the silicon nitride film can be easily adjusted only by adjusting the processing pressure, it is possible to easily manufacture insulating film laminates having various band gap structures. Therefore, it is preferably applied to a process for manufacturing MOS type semiconductor memory devices that combine excellent data retention characteristics, high-speed data rewriting performance, low power consumption operation performance, and high reliability at the same time. It can be done.
- the plasma C VD process will be described by taking as an example the case of forming the insulating film laminate 10 2 b of the MOS type semiconductor memory device 60 1 according to the first embodiment of the present invention. To do.
- an example of manufacturing an insulating film stacked body 10 02a of a MOS semiconductor memory device 60 1 will be taken as an example. The manufacturing method will be described. Here, an example of a typical procedure will be described. Note that the formation of the first insulating film 11 1 1 and the fifth insulating film 1 15 is the same as described in the first embodiment, and thus the description thereof is omitted here.
- a second insulating film 1 1 2, a third insulating film 1 1 3, and a fourth insulating film 1 are formed on the first insulating film 1 1 1 by plasma CVD apparatus 100 using plasma CVD. 1 4 are formed sequentially.
- plasma C V D is performed under a processing condition in which the band gap is smaller than that of the first insulating film 1 1 1.
- plasma C V D is performed under a processing condition in which the band gap is smaller than that of the second insulating film 1 1 2.
- plasma C V D is performed under a processing condition in which the band gap is larger than that of the third insulating film 1 1 3.
- the insulating film is formed under the same plasma CVD conditions so that the second insulating film 1 1 2 and the fourth insulating film 1 1 4 have the same band gap. I do.
- the band gaps 1 1 2 a and 1 1 4 a of the second insulating film 1 1 2 and the fourth insulating film 1 1 4 may be different.
- the band gap size of each film can be easily controlled by changing only the pressure condition of the plasma C VD treatment while keeping the flow rate of the silane gas constant.
- the continuous formation of the insulating film laminate by pressure control as described above can be similarly applied to, for example, the manufacture of the MOS semiconductor memory devices of the second to sixth embodiments. is there.
- the plasma CVD processing pressure is increased during the formation of a single insulating film. It is also possible to change gradually.
- the third insulating film 1 1 3 is formed in the process of manufacturing the MOS type semiconductor memory device 60 1 of FIG. 1 according to the first embodiment, for example, as shown in FIG.
- the processing pressure was gradually increased or decreased step by step with the silane-based gas flow kept constant, or, for example, as shown in Fig. 16, the processing pressure and pressure force were kept constant to make the silane system
- an MMOS semiconductor memory device can be formed with an energy band structure as shown in FIG.
- FIG. 17 shows an example in which the processing pressure is changed so that the band gap 11 a gradually increases in the process of forming the third insulating film 11 13. Contrary to FIG. 17, it is possible to gradually reduce the band gap 1 1 3 a by forming the third insulating film 1 1 3.
- a memory cell array can be formed by arranging the MOS type semiconductor memory devices described in the above embodiment in a matrix.
- the structure of the memory cell array is not particularly limited, and for example, an NOR type, a NAND type, or the like can be adopted as appropriate.
- FIG. 18 shows a configuration example of a NAND type memory cell array 70 1 in which memory cells having the MOS type semiconductor memory device according to the embodiment of the present invention are connected in series.
- Fig. 19 is a cross-sectional view taken along line AA in Fig. 18.
- Figure 20 shows the memory cell shown in Figure 18
- FIG. 7 is an equivalent circuit diagram of the data array 7 0 1.
- FIG. 18 In the present embodiment, as shown in FIG. 18, four memory cells 2 1:! To 2 14 are connected to each bit line BL 1, BL 2. The source diffusion layer and the drain diffusion layer are connected in common. In this way, a large number of memory cells connected in series are arranged to form a NAND-type memory cell array 70 1.
- the n-type silicon substrate 2 0 1 has a p-well 20.2, and memory cells 2 1:! To 2 14 are arranged in series on the p-well 20.2.
- a selection gate electrode 2 2 1 is provided at one end of the four arranged memory cells 2 1 1 to 2 1 4 and a selection gate electrode 2 2 is provided at the other end. Yes.
- the n-type diffusion layer 2 5 0 provided in pwell 2 0 2 is connected to each memory cell 2 1 1
- 2 1 4 may be formed on a p-type silicon substrate or a P-type silicon layer.
- Each memorandum • J cells 2 1.1 to 2 1 4 are composed of a first insulating film 2 3 1 formed on p-well 20 2 and a second insulating film 2 3 1 formed on first insulating film 2 3 1. Insulating film 2 3 2 and third insulating film formed on second insulating film 2 3 2
- Each gate cell 2 1 1 to 2 1 4 having a gate electrode 2 4 0 formed on 5 is formed by insulating film 2 deposited by a method such as a CVD method, for example. 6 0 covered by bit line (BL 1, B
- a 1 or the like metal wiring 2 7 0 is provided.
- the wiring 2 7 0 is connected to the n-type diffusion layer 2 5 0 at the contact portion 2 7 1. Yes.
- the drain side of one end of the memory cell array 7 0 1 is connected to the bit line BL 1 BL 2... Via the selection gate 2 2 1, and the source side of the other end is connected to the selection gate 2 2 2.
- Common source line (ground line) 2 8 0 Connected.
- the gate electrode 24 0 of each memory cell is connected to the bit line B L 1
- FIG. 19 a stacked structure including the first to fifth insulating films 2 3 2 3 5 and the gate electrode 2 4 0 is shown, but each memory cell 2 1 1
- the configuration of 2 14 can be made the same as that of the M S type semiconductor memory device 60 :! 60 6 in the first to sixth embodiments, for example, in this embodiment. 1st 5th insulating film 2 3 1 2 3
- insulating film stacked body 1 0 2 a 1 0 2 d in the MOS type semiconductor memory devices 6 0 1 6 0 4 of the first to fourth embodiments or A configuration having a larger number of insulating films, such as the insulating film stacked body 102 e in the MOS type semiconductor memory device 65 5 of the fifth embodiment, may be adopted. Also in the present embodiment, a configuration having gate electrodes on the upper and lower sides as in the MOS semiconductor device 60 6 of the sixth embodiment may be adopted.
- the memory cell array 70 1 is composed of a large number of units with four memory cells as one unit.
- the memory cell array 7 0 1 can be formed with a larger number of memory cells as one unit.
- FIGS. 21 to 23 show a configuration example of a NOR type memory cell array in which MOS type semiconductor memory devices according to embodiments of the present invention are connected in parallel.
- 2 is a plan view of the NOR type memory cell array 70 2
- FIG. 2 2 is a cross-sectional view taken along line B-B in FIG. 2 1.
- FIG. 23 is an equivalent circuit diagram of the memory cell array 70 2 in FIG.
- NOR type memory cell array 70 2 is arranged in the array.
- p-well 3 0 2 is formed on n-type silicon plate 30 1, and memory cell 3 1 is formed on p-well 3 0 2.
- Each memory cell includes a first insulating film 3 3 1 formed on the p-well 30 2, a second insulating film 3 3 2 formed on the first insulating film 3 3 1, and a second insulating film 3 3 1 Insulating film
- the n-type diffusion layer 3 5 0 serves as the source and drain of each memory cell.
- Each memory cell may be formed on a p-type silicon substrate or p-type silicon layer.
- Each memory cell is covered with an insulating film 36.sub.0 deposited by a method such as C.sub.V D method, for example, and a metal wiring 37.sub.0 such as A.sub.1 is provided thereon.
- the wiring 37 0 is connected to the n-type diffusion layer 3 ⁇ 0 at the contact portion 3 71.
- Each of the memory cells 3 1 1, 3 1 2..., 3 2 1, 3 2 2... Has a gate electrode 3 4 0 arranged in a direction intersecting with the bit lines BL 1, BL 2. Connected to the lead wires WL 1, WL 2.
- the MOS type memory structure having the laminated structure of the first to fifth insulating films 3 3 1 to 3 3 5 and the gate electrode 3 4 0 is shown, but each memory cell 3 1 1, 3 1 2..., 3 2 1, 3 2 2.
- This can be the same as the MOS type semiconductor memory devices 6 01 to 6 0 6 in the first to sixth embodiments. That is, for example, the first to fifth insulating films 33 1 to 3 35 in the present embodiment are replaced with the MOS semiconductor memory devices 60:! To 6 of the first to fourth embodiments.
- Insulating film stacked body in 0 4 may be configured in the same manner as 10 2 a to l 0 2 d, or insulating film stacked body 1 in MOS type semiconductor memory device 6 0 5 of the fifth embodiment As in 0 2 e, a structure having more insulating films may be used. Also in the present embodiment, a configuration having gate electrodes on the upper and lower sides as in the MOS semiconductor device 60 6 of the sixth embodiment may be adopted.
- FIG. 24 is a plan view of the vertical memory cell
- FIG. 25 is a cross-sectional view taken along line C-C in FIG.
- four vertical memory cells 40 0 0 are shown.
- a silicon substrate 4 0 1 of the first conductivity type for example, p-type
- Each vertical memory cell 40 0 is formed around each silicon pillar 4 0 3.
- the second insulating film 4 1 2, the third insulating film 4 1 3, and the fourth insulating film are surrounded by the first insulating film 4 1 1 so as to surround the p-type silicon pillar 4 03.
- a film 4 14 and a fifth insulating film 4 15 are formed in this order, and a gate electrode 4 20 is formed outside thereof.
- An insulating film 40 4 is formed in the groove 4 0 2 with a predetermined thickness so as to cover each vertical memory cell 4 0 0.
- the silicon pillars 4 0 3 are formed on a p-well silicon p-type silicon layer formed in the semiconductor substrate. May be.
- a drain 4 3 1 of an n-type diffusion layer is formed as the second conductivity type on the upper part of each p-type silicon pillar 40 3. Further, a source 4 32 of an n-type diffusion layer is formed below the p-type silicon pillar 40 3.
- the vertical memory cell 400 has a MOS FET structure.
- the gate electrode 4 20 is connected to a word line (not shown).
- the vertical memory cell 40 0 is covered with an insulating film 40 4, and a metal wiring 4 4 0 such as A 1 serving as a bit line BL for commonly connecting the memory cell drain 4 3 1 is provided thereon. ing.
- the metal wiring 44 0 extends in a direction intersecting with the word line (not shown), and is connected to the drain 4 3 1 at the contact flange 4 4 1.
- a positive voltage is applied to the gate electrode 4 2 0 via a selection word line (not shown), and 0 V is applied to the selection bit line BL.
- 0 V is applied to the selection bit line BL.
- the first to fifth insulating films 4 11 1 to 4 15 and the gate electrode 4 2 0 are formed on the side walls of the silicon pillar 4 0 3. It may be formed so as to surround, or may be formed on a part of the side wall of the silicon pillar 40 3.
- the insulating film stacks (first to fifth insulating films 4 11 1 to 4 15 5) serving as regions for accumulating charges are, for example, first to fourth
- the MOS type semiconductor memory devices 6001 to 604 of the embodiment may have a structure in which the stacking direction of the stacks 1002a to l02d is arranged horizontally, or the first As in the MOS type semiconductor memory device 6 05 of the fifth embodiment, a configuration may be adopted in which the insulating film stacked body 10 2 e having a larger number of insulating films is disposed laterally in the stacking direction. Also in the present embodiment, a structure in which two layers of gate electrodes are provided and stacked in the lateral direction as in the MOS type semiconductor device 60 6 of the sixth embodiment may be adopted.
- a stacked memory cell array can also be formed by stacking vertically structured semiconductor memory cells to which the MOS semiconductor memory device of the present invention is applied in a direction perpendicular to the semiconductor substrate.
- FIG. 26 is a plan view of a stacked memory cell array 70 3 in which vertical memory cells are stacked, and FIG. 27 is a cross-sectional view taken along line DD.
- FIG. 26 shows four stacked memory cell arrays 70 3.
- a first conductive type (for example, p-type) silicon substrate 5101 is used.
- a plurality of silicon pillars 5 0 3 separated by lattice-like grooves 5 0 2 are arranged on the silicon substrate 5 0 1, and vertical memory cells 5 0 0 are centered on the respective silicon pillars 5 0 3.
- An insulating film 50 4 having a predetermined thickness is formed in the groove 50 2 formed in the silicon substrate 5 0 1 so as to cover the vertical memory cell 5 0 0.
- the silicon pillar 50 3 may be formed in a p-well or p-type silicon layer formed in the semiconductor substrate.
- Each vertical memory cell 50 0 is formed so as to surround the periphery of the silicon pillar 50 3. That is, the vertical memory cell 5 0 0
- a film 5 15 is formed in order, and a gate electrode 5 20 is formed on the outer side of the film 5 15.
- Select gates 5 2 1 and 5 2 2 are provided on the upper and lower sides of the silicon pillar 50 3 via insulating films 50 5, respectively.
- an n-type diffusion layer 5 31 of the second conductivity type serving as a drain is formed above the silicon pillar 50 3.
- the vertical memory cell 500 has a MO SFET structure. Note that the n-type diffusion layer 5 32 may not be provided as a modification of the present embodiment.
- a plurality of vertical memory cells 500 are vertically aligned with one silicon pillar 5 03 formed on the silicon substrate 5 0 1. Is connected in series.
- the gate electrodes 5 20 of the vertical memory cells 500 are continuously arranged in the row direction to form word lines (not shown).
- a metal wiring such as A 1 serving as the bit line BL that commonly connects the drain 5 3 1 of the vertical memory cell 5 0 0 on the insulating film 5 0 4 covering the vertical memory cell 5 0 0 5 4 0 is provided.
- the metal wiring 5 40 extends in a direction crossing the word line, and is connected to the drain 5 3 1 at the contact portion 5 4 1.
- the drain side is connected to the bit line BL via the selection gate 5 2 1, and the source side is connected to the common source line (n-type diffusion layer 5 3 3) via the selection gate 5 2 2. It is connected.
- the equivalent circuit diagram of this stacked memory cell array 70 3 is the NAND memory shown in Figure 18 It is the same as the cell array.
- the first to fifth insulating films 511 to 515 and the gate electrode 520 are formed so as to surround the side wall of the silicon pillar 503. Alternatively, it may be formed on a part of the side wall of the silicon pillar 50 3.
- the insulating film stacks (first to fifth insulating films 5 11 1 to 5 15 5) serving as regions for accumulating charges in each of the vertical memory cells 500 are used in the first to fourth embodiments, for example.
- the MOS type semiconductor memory device of the form 6 0;! ⁇ 6 0 4 may be structured such that the stacking direction of the insulating film stacks 10 2 a to 100 2 d is ⁇ , or A configuration in which an insulating film stack 10 2 e having a larger number of insulating films is arranged so that the stacking direction is horizontal, as in the MOO type semiconductor memory device 6 0 5 of the fifth embodiment It is good.
- a configuration may be adopted in which two layers of gate electrodes are provided and stacked in the lateral direction, as in the MOS type semiconductor device 60 6 of the sixth embodiment.
Abstract
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KR1020097026696A KR101281911B1 (en) | 2007-06-21 | 2008-06-20 | Mos semiconductor memory device, nand memory cell array, and nor memory cell array |
US12/665,534 US8258571B2 (en) | 2007-06-21 | 2008-06-20 | MOS semiconductor memory device having charge storage region formed from stack of insulating films |
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JP2008092420A JP2009027134A (en) | 2007-06-21 | 2008-03-31 | Mos semiconductor memory device |
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US20100019312A1 (en) * | 2008-07-28 | 2010-01-28 | Katsuyuki Sekine | Semiconductor device and method for manufacturing the same |
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WO2009123335A1 (en) * | 2008-03-31 | 2009-10-08 | 東京エレクトロン株式会社 | Method for manufacturing a mos semiconductor memory device, and plasma cvd device |
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US20100019312A1 (en) * | 2008-07-28 | 2010-01-28 | Katsuyuki Sekine | Semiconductor device and method for manufacturing the same |
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