US20170263629A1 - Semiconductor memory device - Google Patents
Semiconductor memory device Download PDFInfo
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- US20170263629A1 US20170263629A1 US15/257,307 US201615257307A US2017263629A1 US 20170263629 A1 US20170263629 A1 US 20170263629A1 US 201615257307 A US201615257307 A US 201615257307A US 2017263629 A1 US2017263629 A1 US 2017263629A1
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- 239000004065 semiconductor Substances 0.000 title claims abstract description 61
- 238000003860 storage Methods 0.000 claims abstract description 92
- 239000000758 substrate Substances 0.000 claims abstract description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 21
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 21
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 9
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 9
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 20
- 230000005641 tunneling Effects 0.000 description 13
- 150000004767 nitrides Chemical class 0.000 description 12
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 10
- 238000004519 manufacturing process Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 238000005229 chemical vapour deposition Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 238000000151 deposition Methods 0.000 description 4
- 238000005530 etching Methods 0.000 description 4
- 238000001020 plasma etching Methods 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- 238000001039 wet etching Methods 0.000 description 3
- 230000000903 blocking effect Effects 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- -1 for example Inorganic materials 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 238000005036 potential barrier Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
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- H01L27/11582—
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- H01L21/28282—
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/52—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames
- H01L23/522—Arrangements for conducting electric current within the device in operation from one component to another, i.e. interconnections, e.g. wires, lead frames including external interconnections consisting of a multilayer structure of conductive and insulating layers inseparably formed on the semiconductor body
- H01L23/528—Geometry or layout of the interconnection structure
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- H01L27/11565—
-
- 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
- H01L29/41—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions
- H01L29/423—Electrodes ; Multistep manufacturing processes therefor characterised by their shape, relative sizes or dispositions not carrying the current to be rectified, amplified or switched
- H01L29/42312—Gate electrodes for field effect devices
- H01L29/42316—Gate electrodes for field effect devices for field-effect transistors
- H01L29/4232—Gate electrodes for field effect devices for field-effect transistors with insulated gate
- H01L29/4234—Gate electrodes for transistors with charge trapping gate 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
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/40—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
- H01L29/518—Insulating materials associated therewith the insulating material containing nitrogen, e.g. nitride, oxynitride, nitrogen-doped material
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B43/00—EEPROM devices comprising charge-trapping gate insulators
- H10B43/10—EEPROM devices comprising charge-trapping gate insulators characterised by the top-view layout
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B43/00—EEPROM devices comprising charge-trapping gate insulators
- H10B43/20—EEPROM devices comprising charge-trapping gate insulators characterised by three-dimensional arrangements, e.g. with cells on different height levels
- H10B43/23—EEPROM devices comprising charge-trapping gate insulators characterised by three-dimensional arrangements, e.g. with cells on different height levels with source and drain on different levels, e.g. with sloping channels
- H10B43/27—EEPROM devices comprising charge-trapping gate insulators characterised by three-dimensional arrangements, e.g. with cells on different height levels with source and drain on different levels, e.g. with sloping channels the channels comprising vertical portions, e.g. U-shaped channels
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B43/00—EEPROM devices comprising charge-trapping gate insulators
- H10B43/30—EEPROM devices comprising charge-trapping gate insulators characterised by the memory core region
- H10B43/35—EEPROM devices comprising charge-trapping gate insulators characterised by the memory core region with cell select transistors, e.g. NAND
Definitions
- Embodiments described herein relate generally to a semiconductor memory device.
- a semiconductor memory device having a three-dimensional structure wherein memory holes are formed in a stacked body in which multiple electrode layers are stacked, and a charge storage film and a semiconductor film are provided in the memory hole to extend in a stacking direction of the stacked body.
- the semiconductor memory device includes multiple memory cells connected in series between a drain-side select transistor and a source-side select transistor.
- the electrode layers are gate electrodes of the drain-side select transistor, the source-side select transistor and the memory cells, and are formed by removing a portion of the stacked body via a slit of the stacked body and then filling a metal material in the removed portion.
- FIG. 1 is a perspective view of a semiconductor memory device of a first embodiment
- FIG. 2 is a cross-sectional view of the semiconductor memory device of the first embodiment
- FIG. 3 is a plan view of a part of the semiconductor memory device of the first embodiment
- FIG. 4 is a cross-sectional view of a part of the semiconductor memory device of the first embodiment
- FIG. 5 to FIG. 12 are cross-sectional views showing a manufacturing method of the semiconductor memory device of the first embodiment
- FIG. 13 is a plan view of a part of a semiconductor memory device of a second embodiment.
- FIG. 14 is a cross-sectional view of a part of the semiconductor memory device of the second embodiment.
- a semiconductor memory device includes a substrate; a stacked body; a first columnar portion; a second columnar portion; and a plurality of first interconnects.
- the stacked body is provided on the substrate and includes a plurality of electrode layers separately stacked each other.
- the first columnar portion is provided in the stacked body and includes a first semiconductor film extending in a stacking direction of the stacked body, a first charge storage film provided between the stacked body and the first semiconductor film, and a first insulating film provided between the stacked body and the first charge storage film.
- the second columnar portion is provided in the stacked body and includes a second semiconductor film extending in the stacking direction, a second charge storage film provided between the stacked body and the second semiconductor film, and a second insulating film provided between the stacked body and the second charge storage film.
- the plurality of first interconnects is provided on the first columnar portion and the second columnar portion, and extends in a first direction crossing the stacking direction. A distance between the first columnar portion and one end of the plurality of electrode layers in the first direction is smaller than a distance between the second columnar portion and the other end of the plurality of electrode layers in the first direction. In the same electrode layer, a first width of the first charge storage film is smaller than a second width of the second charge storage film.
- FIG. 1 and FIG. 2 are a schematic perspective view and a cross-sectional view of a memory cell array of a semiconductor memory device 1 of a first embodiment.
- illustrations of an insulating layer 42 , an insulating layer 43 , and an insulating film 19 are omitted.
- two mutually-orthogonal directions parallel to a major surface 10 a of a substrate 10 are taken as an X-direction and a Y-direction.
- a direction orthogonal to both the X-direction and the Y-direction is taken as a Z-direction (the stacking direction of a stacked body 15 ).
- the semiconductor memory device 1 includes a stacked body 15 and a plurality of columnar portions CL.
- a plurality of slits ST is provided in the semiconductor memory device 1 .
- the stacked body 15 includes a source-side select gate SGS, a drain-side select gate SGD, a plurality of word lines WL, and a plurality of insulating layers 40 .
- the source-side select gate SGS is provided on the substrate 10 via the insulating layer 40 .
- the substrate 10 is, for example, a semiconductor substrate and includes silicon (Si) such as single-crystal silicon.
- the drain-side select gate SGD is provided at a top layer of the stacked body 15 .
- the plurality of word lines WL is provided between the source-side select gate SGS and the drain-side select gate SGD.
- the source-side select gate SGS, the plurality of word lines WL, and the drain-side select gate SGD are electrode layers.
- the electrode layers contain, for example, metal such as tungsten (W).
- the number of stacked electrode layers is arbitrary.
- the insulating layers 40 are provided between each of the electrode layers (SGS, WL, SGD), respectively.
- the insulating layers 40 contain, for example, silicon oxide (SiO 2 ).
- the insulating layer 41 contains, for example, silicon oxide.
- the source-side select gate SGS and the drain-side select gate SGD are gate electrodes of a source-side select transistor STS and a drain-side select transistor SGD, respectively.
- a plurality of memory cells MC is connected in series between the source-side select transistor STS and the drain-side select transistor STD.
- One of the word lines is used as a gate electrode of the memory cell MC.
- the plurality of columnar portions CL is provided in the stacked body 15 .
- the columnar portion CL extends in the Z-direction in the stacked body 15 .
- the columnar portion CL is formed in a cylindrical shape or an elliptic cylindrical shape.
- the columnar portion CL is disposed in a staggered lattice configuration or a square lattice configuration in the X-Y plane.
- a plurality of bit lines BL extending in the Y-direction is provided above the columnar portions CL.
- a top end of the columnar portion CL is connected to one of the bit lines BL via a contact portion 30 .
- the contact portion 30 is a contact plug and made of conductor such as metal.
- the slit ST is provided in the stacked body 15 .
- the slit ST extends along the Z-direction and the X-direction in the stacked body 15 .
- the slit ST divides the stacked body 15 into a plural in the Y-direction.
- the region that is divided by the slit ST is called a “block”.
- One columnar portion CL which is selected from each block is electrically connected to one bit line BL.
- the plurality of slits ST is provided in the stacked body 15 , and an interconnect portion 18 is provided in the slit ST.
- the interconnect portion 18 extends in the Z-direction and the X-direction. A bottom end of the interconnect portion 18 is contact with the substrate 10 .
- the interconnect portion 18 contains metal such as tungsten (W).
- a source line SL extending the Y-direction is provided above the interconnect portion 18 .
- a top end of the interconnect portion 18 is connected to the source line SL via a contact portion 31 .
- the contact portion 31 is a contact plug and made of conductor such as metal.
- the columnar portion CL includes a core portion 60 , a semiconductor body 20 , a tunneling insulating film 21 , a charge storage film 22 , and an oxide film 23 a .
- the core portion 60 contains silicon oxide (SiO 2 ).
- a shape of the core portion 60 is, for example, a columnar shape.
- the semiconductor body 20 is provided around the core portion 60 .
- the semiconductor body 20 contains silicon, for example, polysilicon made of crystallized amorphous silicon.
- a shape of the semiconductor body 20 is, for example, a cylinder shape with a bottom.
- a bottom end of the semiconductor body 20 is contact with the substrate 10 .
- a plug portion 32 is provided on a top end of the core portion 60 .
- the plug portion 32 is located in the insulating layer 41 , and the semiconductor body 20 surrounds the plug portion 32 .
- the plug portion 32 is formed by the same material as the semiconductor body 20 .
- the tunneling insulating film 21 is provided around the semiconductor body 20 .
- the tunneling insulating film 21 contains, for example, silicon oxide.
- a shape of the tunneling insulating film 21 is a cylinder shape.
- the charge storage film 22 is provided around the tunneling insulating film 21 .
- the charge storage film 22 contains silicon nitride (Si 3 N 4 ).
- a shape of the charge storage film 22 is a cylinder shape.
- the memory cell MC including the charge storage film 22 is provided at an intersection between the semiconductor body 20 and the word line WL.
- the tunneling insulating film 21 is a potential barrier between the charge storage film 22 and the semiconductor body 20 . Tunneling of the charge occurs in the tunneling insulating film 21 when the charge is moved from the semiconductor body 20 to the charge storage film 22 (a programming operation) and when the charge is moved from the charge storage film 22 to the semiconductor body 20 (an erasing operation).
- the charge storage film 22 has a trap site trapping the charge in the film.
- the threshold of the memory cell MC changes due to the presence/absence and amount of the charge trapped in the trap site. Thereby, the memory cell MC retains information.
- the oxide film 23 a is provided around the charge storage film 22 .
- the oxide film 23 a contains silicon oxide (SiO 2 ).
- the oxide film 23 a protects, for example, the charge storage film 22 from etching.
- the memory film 24 is composed of the tunneling insulating film 21 , the charge storage film 22 , and the oxide film 23 a.
- An oxide film 23 c is provided around the oxide film 23 a . Also, the oxide film 23 c is provided between each of the electrode layers (SGS, WL, SGD) and the insulating layer 40 . For example, the oxide film 23 c contains aluminum oxide (Al 2 O 3 ). A blocking insulating film 23 is composed of the oxide film 23 a and the oxide film 23 c.
- the insulating layer 42 is provided on the columnar portion CL and the insulating layer 41 .
- the insulating layer 43 is provided on the insulating layer 42 .
- the insulating layer 42 and the insulating layer 43 contain, for example, silicon oxide.
- the contact portion 30 is located in the insulating layer 42 and the insulating layer 43 . A top end of the contact portion 30 is connected to the bit line BL, and a bottom end of the contact portion 30 is connected to the plug portion 32 .
- the insulating film 19 is provided in the slit ST.
- the insulating film 19 is provided at the sidewall of the interconnect portion 18 and extends in the Z-direction and the X-direction.
- the insulating film 19 contains, for example, silicon oxide.
- the insulating film 19 electrically insulates the interconnect portion 18 and each of the electrode layers (SGS, WL, SGD) of the stacked body 15 .
- a plate portion PT is composed of the interconnect portion 18 and the insulating film 19 .
- the plate portion PT penetrates the insulating layer 42 , the insulating layer 41 , and the stacked body 15 , and a bottom end of the plate portion PT is contact with the substrate 10 .
- FIG. 3 is an enlarged plan view extracting one portion of the word line WL between the slits ST.
- FIG. 4 is an enlarged view of an area A of FIG. 2 , and is a view including an area corresponding to the Y-Z cross-section by the A 1 -A 2 line of FIG. 3 .
- the interconnect portion 18 A, the insulating film 19 A 1 , and the insulating film 19 A 2 extending in X-direction are provided in the slit ST 1 .
- the plate portion PT 1 is composed of the interconnect portion 18 A, the insulating film 19 A 1 , and the insulating film 19 A 2 .
- the interconnect portion 18 B, the insulating film 19 B 1 , and the insulating film 19 B 2 extending in the X-direction are provided in the slit ST 2 .
- the plate portion PT 2 is composed of the interconnect portion 18 B, the insulating film 1961 , and the insulating film 1962 .
- the plurality of columnar portions CL is disposed in a staggered lattice configuration between the slit ST 1 and the slit ST 2 .
- the columnar portions CL 1 a , CL 1 b , CL 2 a , CL 2 b , CL 3 a , CL 3 b , CL 4 a , CL 4 b are disposed in the word line WL.
- the columnar portion CL 1 a and the columnar portion CL 1 b are located on the same straight line. Further, if a virtual straight line along the X-direction has been set on the word line WL, the columnar portion CL 2 a and the columnar portion CL 2 b , the columnar portion CL 3 a and the columnar portion CL 3 b , and the columnar portion CL 4 a and the columnar portion CL 4 b are located on the same straight line, respectively.
- the number of the columnar portions CL is arbitrary.
- the columnar portions CL 1 a , CL 1 b , CL 2 a , CL 2 b are disposed at the slit ST 1 side of the word line WL
- the columnar portions CL 3 a , CL 3 b , CL 4 a , CL 4 b are disposed at the slit ST 2 side of the word line WL.
- the straight line DC is a virtual straight line which is set along the X-direction on the word line WL; and when the width of the word line WL in the Y-direction is represented by W 1 , the straight line DC is the straight line located at a distance of W 1 / 2 in Y-direction from the slit ST 1 and the slit ST 2 .
- distances in the Y-direction between the columnar portion CLla and the slit ST 1 and between the columnar portion CL 1 b and the slit ST 1 are short as compared with distances in the Y-direction between the columnar portion CL 2 a and the slit ST 1 and between the columnar portion CL 2 b and the slit ST 1 .
- the columnar portions CL 1 a , CL 1 b are disposed so that the distances in the Y-direction between the columnar portion CL 1 a and the slit ST 1 and between the columnar portion CL 1 b and the slit ST 1 are the shortest distance among all the columnar portions CL.
- distances in the Y-direction between the columnar portion CL 4 a and the slit ST 2 and between the columnar portion CL 4 b and the slit ST 2 are short as compared with distances in the Y-direction between the columnar portion CL 3 a and the slit ST 2 and between the columnar portion CL 3 b and the slit ST 2 .
- the columnar portions CL 4 a , CL 4 b are disposed so that the distances in the Y-direction between the columnar portion CL 4 a and the slit ST 2 and between the columnar portion CL 4 b and the slit ST 2 are the shortest distance among all the columnar portions CL.
- the columnar portions CL 1 a , CL 1 b , CL 4 a , CL 4 b are disposed so that the distance is shortest between any of the slit ST 1 and the slit ST 2 .
- the columnar portions CL 2 a , CL 2 b , CL 3 a , CL 3 b are disposed in a central portion of the word line WL that the straight line DC is formed.
- the columnar portions CL 1 a , CL 1 b , CL 4 a , CL 4 b are disposed at the outside of the word line WL, and the columnar portions CL 2 a , CL 2 b , CL 3 a , CL 3 b are disposed at the inside of the word line WL.
- the columnar portions CL 1 a , CL 1 b , CL 4 a , CL 4 b are disposed at the outside of the insulating layer 40
- the columnar portions CL 2 a , CL 2 b , CL 3 a , CL 3 b are disposed at the inside of the insulating layer 40 .
- the distance between the slit ST and the columnar portion CL disposed at the outside of the word line WL is shorter as compared with the distance between the slit ST and the columnar portion CL disposed at the inside of the word line WL.
- a distance d 1 in the Y-direction between the slit ST 1 and the columnar portion CL 1 b disposed at the outside of the word line WL is smaller than a distance d 2 in the Y-direction between the slit ST 2 and the columnar portion CL 3 b disposed at the inside of the word line WL.
- the distance d 1 is a distance between the columnar portion CL 1 b and an end portion t 1 of the word line WL
- the distance d 2 is a distance between the columnar portion CL 3 b and an end portion t 2 of the word line WL.
- the columnar portions CL 1 b , CL 3 b are located in the word line WL.
- the oxide film 23 a 1 has an oxide portion 23 b 1 provided around the charge storage film 22 a 1 .
- the oxide portion 23 b 1 overlaps with a part of the charge storage film 22 a 1 of the columnar portion CL 1 b which is located in the insulating layer 40 , as viewed in the Z-direction.
- the oxide film 23 a 2 has an oxide portion 23 b 2 provided around the charge storage film 22 a 2 .
- the oxide portion 23 b 2 overlaps with a part of the charge storage film 22 a 2 of the columnar portion CL 3 b which is located in the insulating layer 40 , as viewed in the Z-direction.
- the oxide portion 23 b 1 is a portion which is formed by oxidizing a part of the charge storage film 22 a 1 of the columnar portion CL 1 b located in the word line WL.
- the oxide portion 23 b 2 is a portion which is formed by oxidizing a part of the charge storage film 22 a 2 of the columnar portion CL 3 b located in the word line WL. If the charge storage films 22 a 1 , 22 a 2 are formed by silicon nitride, the oxide portions 23 b 1 , 23 b 2 are, for example, formed by radical oxidizing of the silicon nitride.
- a width W 2 of the oxide portion 23 b 1 of the columnar portion CL 1 b is greater than a width W 3 of the oxide portion 23 b 2 of the columnar portion CL 3 b .
- a width W 4 of the charge storage film 22 a 1 of the columnar portion CL 1 b is smaller than a width W 5 of the charge storage film 22 a 2 of the columnar portion CL 3 b .
- the width W 4 and the width W 5 may be thicknesses capable of storing charges in the charge storage films 22 a 1 , 22 a 2 , and the thicknesses are, for example, 5 nanometers or more.
- a width W 6 of the oxide film 23 a 1 of the columnar portion CL 1 b is a width W 7 of the oxide film 23 a 2 of the columnar portion CL 3 b or less.
- the width W 6 and the width W 7 will be approximately the same.
- the columnar portions CL are located in the same word line WL” refers to the columnar portions CL are located in one of the same word line WL which extends in the X-direction in the stacked body 15 .
- widths of the charge storage film 22 a 1 of the columnar portion CL 1 b will be approximately the same. Further, widths of the oxide film 23 a 1 of the columnar portion CL 1 b will be approximately the same.
- widths of the charge storage film 22 a 2 of the columnar portion CL 3 b will be approximately the same. Further, widths of the oxide film 23 a 2 of the columnar portion CL 3 b will be approximately the same.
- FIG. 5 to FIG. 12 are cross-sectional views showing a manufacturing method of the semiconductor memory device of the first embodiment.
- FIG. 5 to FIG. 8 are cross-sectional views showing a manufacturing process of a region shown in FIG. 2 , and show a portion lower than the insulating layer 43 .
- FIG. 9 is an enlarged view of a region “B” shown in FIG. 8 .
- the insulating layer 40 and the sacrificial layer 50 are alternately stacked on the substrate 10 along the Z-direction by, for example, CVD (Chemical Vapor Deposition) method to form a stacked body 15 a .
- the insulating layer 40 is formed using silicon oxide.
- the sacrificial layer 50 is formed using a material, which may be takes an etching selectivity ratio with respect to the insulating layer 40 , and is formed using silicon nitride, for example.
- the insulating layer 41 is formed on the stacked body 15 a.
- a plurality of memory holes 51 is formed in the insulating layer 41 and the stacked body 15 a by, for example, RIE (Reactive Ion Etching).
- the memory holes 51 extend in the Z-direction, pierce the insulating layer 41 and the stacked body 15 a , and reach the substrate 10 .
- the memory holes 51 having a circular shape are disposed in a staggered configuration.
- silicon oxide is deposited on an inner surface of the memory hole 51 to form an oxide film 23 A
- silicon nitride is deposited to form a nitride film 22 A
- silicon oxide is deposited to form the tunneling insulating film 21 .
- the tunneling insulating film 21 , the nitride film 22 A, and the oxide film 23 A are removed from a bottom surface of the memory hole 51 by performing RIE to expose the substrate 10 .
- the semiconductor body 20 is formed by depositing silicon, and the core portion 60 is formed by depositing silicon oxide.
- the semiconductor body 20 is contact with the substrate 10 .
- the plug portion 32 is formed by removing an upper portion of the core portion 60 using etch back, and embedding silicon that impurities are doped.
- the insulating layer 42 is formed on the insulating layer 41 .
- a plurality of slits ST 1 , ST 2 extending in the X-direction are formed in the stacked body 15 a by, for example, anisotropic etching such as RIE.
- the slits ST 1 , ST 2 are caused to pierce the insulating layer 42 , the insulating layer 41 , and the stacked body 15 a .
- the stacked body 15 a is divided into a plurality of stacked bodies extending in the X-direction by the slits ST 1 , ST 2 .
- one of the memory holes 51 (the memory hole 51 A) shown in FIG. 7 is disposed at outsides of the insulating layer 40 and the sacrificial layer 50
- the other of the memory holes 51 (the memory hole 51 B) shown in FIG. 7 is disposed at insides of the insulating layer 40 and the sacrificial layer 50 .
- the nitride film 22 A 1 and the oxide film 23 A 1 are formed in the memory hole 51 A
- the nitride film 22 A 2 and the oxide film 23 A 2 are formed in the memory hole 51 B.
- the sacrificial layers 50 are removed by performing wet etching via the slits ST 1 , ST 2 . If the sacrificial layers 50 are formed by silicon nitride, phosphoric acid is used as an etchant of the wet etching, and the processing is performed using hot phosphoric acid. By removing the sacrificial layers 50 via the slits ST 1 , ST 2 , spaces 53 are formed.
- a width Wa 1 of the oxide film 23 A 1 of the memory hole 51 A is smaller than a width Wa 2 of the oxide film 23 A 2 of the memory hole 51 B.
- a distance d 3 between the slit ST 1 and the memory hole 51 A is smaller than a distance d 4 between the slit ST 2 and the memory hole 51 B. Therefore, when removing the sacrificial layers 50 , the oxide film 23 A 1 is in contact with hot phosphoric acid long time as compared with the oxide film 23 A 2 .
- the oxide film 23 A 1 is further etched by hot phosphoric acid, and the film thickness of the oxide film 23 A 1 is smaller than the film thickness of the oxide film 23 A 2 .
- the above is a simplified flow of a manufacturing method of the semiconductor memory device 1 , but in the embodiment, the formation of the oxide film 23 a , the oxide film 23 c , and the electrode layers (SGS, WL, SGD) are performed as follows. About this process will be described with reference to FIG. 10 to FIG. 12 .
- cross-sections shown in FIG. 10 to FIG. 12 correspond to the cross-section shown in FIG. 9 .
- radical oxidation process is performed to the nitride films 22 A 1 , 22 A 2 via the slits ST 1 , ST 2 , and the spaces 53 .
- a part of the nitride film 22 A 1 is oxidized via the oxide film 23 A 1 in the memory hole 51 A
- a part of the nitride film 22 A 2 is oxidized via the oxide film 23 A 2 in the memory hole 51 B.
- side surfaces of the oxide films 23 A 1 , 23 A 2 are expanded to both side of the Y-direction.
- the charge storage film 22 a 1 and the oxide film 23 a 1 are formed in the memory hole 51 A, and the charge storage film 22 a 2 and the oxide film 23 a 2 are formed in the memory hole 51 B.
- the oxide films 23 a 1 , 23 a 2 have the oxide portions 23 b 1 , 23 b 2 , respectively. Since the width of the oxide film 23 A 1 is smaller than the width of the oxide film 23 A 2 , the nitride film 22 A 1 is easily oxidized than the nitride film 22 A 2 . Therefore, the width W 2 of the oxide portion 23 b 1 is greater than the width W 3 of the oxide portion 23 b 2 .
- the columnar portion CLA is formed in the memory hole 51 A, and includes the core portion 60 , the semiconductor body 20 , the tunneling insulating film 21 , the charge storage film 22 a 1 , and the oxide film 23 a 1 .
- the columnar portion CLB is formed in the memory hole 51 B, and includes the core portion 60 , the semiconductor body 20 , the tunneling insulating film 21 , the charge storage film 22 a 2 , and the oxide film 23 a 2 .
- the columnar portion CLA is disposed at the outside of the insulating layer 40
- the columnar portion CLB is disposed at the inside of the insulating layer 40 .
- the columnar portion CLA corresponds to any of the columnar portions CL 1 a , CL 1 b , CL 4 a , CL 4 b as shown in FIG. 3 .
- the columnar portion CLB corresponds to any of the columnar portions CL 2 a , CL 2 b , CL 3 a , CL 3 b as shown in FIG. 3 .
- the oxide film 23 c is formed by depositing aluminum oxide on an entire surface, for example, using CVD method.
- the oxide film 23 c is formed around the oxide films 23 a 1 , 23 a 2 and on the insulating layer 40 . Thereby, the blocking insulating film 23 is formed.
- the radical oxidation process of the nitride films 22 A 1 , 22 A 2 shown in FIG. 10 may be performed after forming the oxide film 23 c .
- a part of the nitride film 22 A 1 is oxidized via the oxide film 23 c and the oxide film 23 A 1 in the memory hole 51 A
- a part of the nitride film 22 A 2 is oxidized via the oxide film 23 c and the oxide film 23 A 2 in the memory hole 51 B.
- conductive layers are formed on an entire surface by, for example, CVD method.
- the conductive layer also enters an interior of the space 53 via the slits ST 1 , ST 2 .
- the conductive layers are etched by isotropic etching such as CDE (Chemical Dry Etching) or wet etching so as not to short the adjacent conductive layers in the Z-direction.
- CDE Chemical Dry Etching
- wet etching so as not to short the adjacent conductive layers in the Z-direction.
- the stacked body 15 including the electrode layers (SGS, WL, SGD) and the plurality of insulating layers 40 is formed.
- the width W 4 of the charge storage films 22 a 1 of the columnar portion CLA is smaller than the width W 5 of the charge storage film 22 a 2 of the columnar portion CLB.
- the width W 6 of the oxide film 23 a 1 of the columnar portion CLA is the width W 7 of the oxide film 23 a 2 of the columnar portion CLB or less.
- an insulating film is etched back to leave on side surfaces of the slits ST 1 , ST 2 , thereby forming the insulating films 19 .
- metal such as tungsten is deposited in the slits ST 1 , ST 2 to form the interconnect portions 18 .
- the semiconductor device 1 according to the first embodiment is manufactured.
- the semiconductor memory device having a three-dimensional structure
- a plurality of memory holes sometimes is disposed such that the difference in distance between the slit occurs.
- the oxide film formed in the memory hole having a short distance from the slit is in contact long to hot phosphoric acid as compared to the oxide film formed in the memory hole having a long distance from the slit.
- the oxide film exposed to hot phosphoric acid for a long period of time is easily etched by hot phosphoric acid. Thereby, there is a possibility that variation arises in the thickness of the oxide film formed in each memory hole depending on the distance between the memory hole and the slit.
- the width of the charge storage film 22 of the columnar portion CL disposed at the outside of the word line WL is smaller than the width of the charge storage film 22 of the columnar portion CL disposed at the inside of the word line WL. Further, the width of the oxide film 23 a of the columnar portion CL disposed at the outside of the word line WL is the width of the oxide film 23 a of the columnar portion CL disposed at the inside of the word line WL or less.
- the plurality of columnar portions CL When the plurality of columnar portions CL is disposed in this manner, it is possible to reduce the difference of the widths of the oxide films 23 a in the same word line WL. Since uniformity of a width of each oxide film 23 a can be ensured, it is possible to suppress the moving of the charge in the charge storage film 22 via the oxide film 23 a having a thin thickness. In other words, since leak currents via the oxide film 23 a can be suppressed, charge retention characteristic of the charge storage film 22 is improved.
- each oxide film 23 a can be ensured, for example, when the charge is moved from the semiconductor body 20 to the charge storage film 22 (programming operation), it is possible to reduce variation of a programming speed of the memory cell MC. Therefore, an operating characteristic of the memory cell MC can be improved.
- FIG. 13 is an enlarge plan view extracting one portion of the word line WL between the slits ST.
- FIG. 14 is the Y-Z cross-sectional view by the B 1 -B 2 line of FIG. 13 .
- the embodiment and the first embodiment are different in the arrangement of the columnar portions CL in the word line WL. Since structure except for the arrangement of the columnar portions CL is same as the first embodiment, detailed description of the other structure is omitted.
- the plurality of columnar portions CL is disposed in a staggered lattice configuration between the slit ST 1 and the slit ST 2 .
- the columnar portions CL 1 a , CL 1 b , CL 2 a , CL 2 b , CL 3 a , CL 3 b , CL 4 a , CL 4 b , CL 5 a , CL 5 b , CL 6 a , CL 6 b are disposed in the word line WL. If a virtual straight line along the X-direction has been set on the word line WL, the columnar portion CL 1 a and the columnar portion CL 1 b are located on the same straight line.
- the columnar portion CL 2 a and the columnar portion CL 2 b , the columnar portion CL 3 a and the columnar portion CL 3 b , the columnar portion CL 4 a and the columnar portion CL 4 b , the columnar portion CL 5 a and the columnar portion CL 5 b , and the columnar portion CL 6 a and the columnar portion CL 6 b are located on the same straight line, respectively.
- the columnar portions CL 1 a , CL 1 b , CL 2 a , CL 2 b are disposed at the slit ST 1 side of the word line WL, and the columnar portions CL 3 a , CL 3 b , CL 4 a , CL 4 b are disposed at the slit ST 2 side of the word line WL.
- the columnar portion CL 5 a is located between the columnar portion CL 1 a and the columnar portion CL 3 a
- the columnar portion CL 5 b is located between the columnar portion CL 1 b and the columnar portion CL 3 b
- the columnar portion CL 6 a is located between the columnar portion CL 2 a and the columnar portion CL 4 a
- the columnar portion CL 6 b is located between the columnar portion CL 2 b and the columnar portion CL 4 b.
- the columnar portions CL 1 a , CL 1 b are disposed so that the distances between the columnar portion CL 1 a and the slit ST 1 and between the columnar portion CL 1 b and the slit ST 1 are the shortest distance among all the columnar portions CL.
- the columnar portions CL 4 a , CL 4 b are disposed so that the distances between the columnar portion CL 4 a and the slit ST 2 and between the columnar portion CL 4 b and the slit ST 2 are the shortest distance among all the columnar portions CL.
- the columnar portions CL 2 a , CL 2 b are disposed so that the distances between the columnar portion CL 2 a and the slit ST 1 and between the columnar portion CL 2 b and the slit ST 1 are short as compared with distances between the columnar portion CL 6 a and the slit ST 1 and between the columnar portion CL 6 b and the slit ST 1 .
- the columnar portions CL 3 a , CL 3 b are disposed so that the distances between the columnar portion CL 3 a and the slit ST 2 and between the columnar portion CL 3 b and the slit ST 2 are short as compared with distances between the columnar portion CL 5 a and the slit ST 2 and between the columnar portion CL 5 b and the slit ST 2 .
- the columnar portions CL 1 a , CL 1 b , CL 2 a , CL 2 b , CL 3 a , CL 3 b , CL 4 a , CL 4 b are disposed at the outside of the word line WL, and the columnar portions CL 5 a , CL 5 b , CL 6 a , CL 6 b are disposed at the inside of the word line WL.
- the columnar portions CL 1 b , CL 3 b , CL 5 b are located in the word line WL.
- the oxide film 23 a 1 has the oxide portion 23 b 1 provided around the charge storage film 22 a 1 . As viewed in the Z-direction, the oxide portion 23 b 1 overlaps with a part of the charge storage film 22 a 1 of the columnar portion CL 1 b which is located in the insulating layer 40 .
- the oxide film 23 a 2 has the oxide portion 23 b 2 provided around the charge storage film 22 a 2 . As viewed in the Z-direction, the oxide portion 23 b 2 overlaps with a part of the charge storage film 22 a 2 of the columnar portion CL 3 b which is located in the insulating layer 40 .
- the oxide film 23 a 3 has the oxide portion 23 b 3 provided around the charge storage film 22 a 3 . As viewed in the Z-direction, the oxide portion 23 b 3 overlaps with a part of the charge storage film 22 a 3 of the columnar portion CL 5 b which is located in the insulating layer 40 .
- the width W 2 of the oxide portion 23 b 1 of the columnar portion CL 1 b is greater than the width W 3 of the oxide portion 23 b 2 of the columnar portion CL 3 b .
- the width W 3 is greater than a width W 8 of the oxide portion 23 b 3 of the columnar portion CL 5 b.
- the width W 4 of the charge storage film 22 a 1 of the columnar portion CL 1 b is smaller than the width W 5 of the charge storage film 22 a 2 of the columnar portion CL 3 b .
- the width W 5 is smaller than a width W 9 of the charge storage film 22 a 3 of the columnar portion CL 5 b .
- the width W 4 , the width W 5 , and the width W 9 are, for example, 5 nanometers or more.
- the width W 6 of the oxide film 23 a 1 of the columnar portion CL 1 b is the width W 7 of the oxide film 23 a 2 of the columnar portion CL 3 b or less.
- the width W 7 is a width W 10 of the oxide film 23 a 3 of the columnar portion CL 5 b or less.
- the width W 6 , the width W 7 , and the width 10 will be approximately the same.
- the width of the charge storage film 22 of the columnar portion CL disposed at the outside of the word line WL is smaller than the width of the charge storage film 22 of the columnar portion CL disposed at the inside of the word line WL. Further, in the plurality of columnar portions CL disposed at the outside of the word line WL, the width of the charge storage film 22 of the columnar portion CL having a short distance between the slit ST and the columnar portion CL is smaller than the width of the charge storage film 22 of the columnar portion CL having a long distance between the slit ST and the columnar portion CL.
- the width of the oxide film 23 a of the columnar portion CL disposed at the outside of the word line WL is the width of the oxide film 23 a of the columnar portion CL disposed at the inside of the word line WL or less.
- the width of the oxide film 23 a of the columnar portion CL having a short distance between the slit ST and the columnar portion CL is the width of the oxide film 23 a of the columnar portion CL having a long distance between the slit ST and the columnar portion CL or less.
- the plurality of columnar portions CL When the plurality of columnar portions CL is disposed in this manner, it is possible to reduce the difference of the widths of the oxide films 23 a in the same word line WL. Thereby, it is possible to ensure the uniformity of the width of each oxide film 23 a and suppress the reducing of the charge retention characteristic of the charge storage film 22 of each memory cell MC. Further, since the programming speed of the memory cell MC is increased, the operating characteristic of the memory cell MC is improved.
- the number of the columnar portions CL and the arrangement of the columnar portions CL are arbitrary.
- any number of the columnar portions CL may be disposed in the word line WL in the Y-direction.
Abstract
Description
- This application is based upon and claims the benefit of priority from U.S. Provisional Patent Application 62/305,177 filed on Mar. 8, 2016; the entire contents of which are incorporated herein by reference.
- Embodiments described herein relate generally to a semiconductor memory device.
- A semiconductor memory device having a three-dimensional structure is proposed, wherein memory holes are formed in a stacked body in which multiple electrode layers are stacked, and a charge storage film and a semiconductor film are provided in the memory hole to extend in a stacking direction of the stacked body. The semiconductor memory device includes multiple memory cells connected in series between a drain-side select transistor and a source-side select transistor. The electrode layers are gate electrodes of the drain-side select transistor, the source-side select transistor and the memory cells, and are formed by removing a portion of the stacked body via a slit of the stacked body and then filling a metal material in the removed portion. When removing the portion of the stacked body, there is a possibility that variation arises in the thickness of film formed in each memory hole depending on a distance between the memory hole and the slit. Thus, it is concerned that failure occurs in the operation of the memory cell.
-
FIG. 1 is a perspective view of a semiconductor memory device of a first embodiment; -
FIG. 2 is a cross-sectional view of the semiconductor memory device of the first embodiment; -
FIG. 3 is a plan view of a part of the semiconductor memory device of the first embodiment; -
FIG. 4 is a cross-sectional view of a part of the semiconductor memory device of the first embodiment; -
FIG. 5 toFIG. 12 are cross-sectional views showing a manufacturing method of the semiconductor memory device of the first embodiment; -
FIG. 13 is a plan view of a part of a semiconductor memory device of a second embodiment; and -
FIG. 14 is a cross-sectional view of a part of the semiconductor memory device of the second embodiment. - According to one embodiment, a semiconductor memory device includes a substrate; a stacked body; a first columnar portion; a second columnar portion; and a plurality of first interconnects. The stacked body is provided on the substrate and includes a plurality of electrode layers separately stacked each other. The first columnar portion is provided in the stacked body and includes a first semiconductor film extending in a stacking direction of the stacked body, a first charge storage film provided between the stacked body and the first semiconductor film, and a first insulating film provided between the stacked body and the first charge storage film. The second columnar portion is provided in the stacked body and includes a second semiconductor film extending in the stacking direction, a second charge storage film provided between the stacked body and the second semiconductor film, and a second insulating film provided between the stacked body and the second charge storage film. The plurality of first interconnects is provided on the first columnar portion and the second columnar portion, and extends in a first direction crossing the stacking direction. A distance between the first columnar portion and one end of the plurality of electrode layers in the first direction is smaller than a distance between the second columnar portion and the other end of the plurality of electrode layers in the first direction. In the same electrode layer, a first width of the first charge storage film is smaller than a second width of the second charge storage film.
- Embodiments will now be described with reference to the drawings. In the respective drawings, same members are labeled with same reference numerals.
-
FIG. 1 andFIG. 2 are a schematic perspective view and a cross-sectional view of a memory cell array of a semiconductor memory device 1 of a first embodiment. In theFIG. 1 , illustrations of aninsulating layer 42, aninsulating layer 43, and aninsulating film 19 are omitted. - In the specification, two mutually-orthogonal directions parallel to a
major surface 10 a of asubstrate 10 are taken as an X-direction and a Y-direction. A direction orthogonal to both the X-direction and the Y-direction is taken as a Z-direction (the stacking direction of a stacked body 15). - As shown in
FIG. 1 , the semiconductor memory device 1 includes a stackedbody 15 and a plurality of columnar portions CL. A plurality of slits ST is provided in the semiconductor memory device 1. The stackedbody 15 includes a source-side select gate SGS, a drain-side select gate SGD, a plurality of word lines WL, and a plurality ofinsulating layers 40. - The source-side select gate SGS is provided on the
substrate 10 via theinsulating layer 40. Thesubstrate 10 is, for example, a semiconductor substrate and includes silicon (Si) such as single-crystal silicon. The drain-side select gate SGD is provided at a top layer of the stackedbody 15. The plurality of word lines WL is provided between the source-side select gate SGS and the drain-side select gate SGD. The source-side select gate SGS, the plurality of word lines WL, and the drain-side select gate SGD are electrode layers. The electrode layers contain, for example, metal such as tungsten (W). The number of stacked electrode layers is arbitrary. - The
insulating layers 40 are provided between each of the electrode layers (SGS, WL, SGD), respectively. Theinsulating layers 40 contain, for example, silicon oxide (SiO2). - An
insulating layer 41 is provided on the stackedbody 15. Theinsulating layer 41 contains, for example, silicon oxide. - The source-side select gate SGS and the drain-side select gate SGD are gate electrodes of a source-side select transistor STS and a drain-side select transistor SGD, respectively. A plurality of memory cells MC is connected in series between the source-side select transistor STS and the drain-side select transistor STD. One of the word lines is used as a gate electrode of the memory cell MC.
- The plurality of columnar portions CL is provided in the stacked
body 15. The columnar portion CL extends in the Z-direction in thestacked body 15. The columnar portion CL is formed in a cylindrical shape or an elliptic cylindrical shape. For example, the columnar portion CL is disposed in a staggered lattice configuration or a square lattice configuration in the X-Y plane. - A plurality of bit lines BL extending in the Y-direction is provided above the columnar portions CL. A top end of the columnar portion CL is connected to one of the bit lines BL via a
contact portion 30. Thecontact portion 30 is a contact plug and made of conductor such as metal. - The slit ST is provided in the
stacked body 15. The slit ST extends along the Z-direction and the X-direction in thestacked body 15. The slit ST divides thestacked body 15 into a plural in the Y-direction. The region that is divided by the slit ST is called a “block”. One columnar portion CL which is selected from each block is electrically connected to one bit line BL. - The plurality of slits ST is provided in the
stacked body 15, and aninterconnect portion 18 is provided in the slit ST. Theinterconnect portion 18 extends in the Z-direction and the X-direction. A bottom end of theinterconnect portion 18 is contact with thesubstrate 10. For example, theinterconnect portion 18 contains metal such as tungsten (W). - A source line SL extending the Y-direction is provided above the
interconnect portion 18. A top end of theinterconnect portion 18 is connected to the source line SL via acontact portion 31. Thecontact portion 31 is a contact plug and made of conductor such as metal. - As shown in
FIG. 2 , the columnar portion CL includes acore portion 60, asemiconductor body 20, a tunneling insulatingfilm 21, acharge storage film 22, and anoxide film 23 a. For example, thecore portion 60 contains silicon oxide (SiO2). A shape of thecore portion 60 is, for example, a columnar shape. - The
semiconductor body 20 is provided around thecore portion 60. Thesemiconductor body 20 contains silicon, for example, polysilicon made of crystallized amorphous silicon. A shape of thesemiconductor body 20 is, for example, a cylinder shape with a bottom. A bottom end of thesemiconductor body 20 is contact with thesubstrate 10. - A
plug portion 32 is provided on a top end of thecore portion 60. Theplug portion 32 is located in the insulatinglayer 41, and thesemiconductor body 20 surrounds theplug portion 32. For example, theplug portion 32 is formed by the same material as thesemiconductor body 20. - The tunneling insulating
film 21 is provided around thesemiconductor body 20. The tunneling insulatingfilm 21 contains, for example, silicon oxide. For example, a shape of the tunneling insulatingfilm 21 is a cylinder shape. - The
charge storage film 22 is provided around the tunneling insulatingfilm 21. For example, thecharge storage film 22 contains silicon nitride (Si3N4). For example, a shape of thecharge storage film 22 is a cylinder shape. The memory cell MC including thecharge storage film 22 is provided at an intersection between thesemiconductor body 20 and the word line WL. - The tunneling insulating
film 21 is a potential barrier between thecharge storage film 22 and thesemiconductor body 20. Tunneling of the charge occurs in the tunneling insulatingfilm 21 when the charge is moved from thesemiconductor body 20 to the charge storage film 22 (a programming operation) and when the charge is moved from thecharge storage film 22 to the semiconductor body 20 (an erasing operation). - The
charge storage film 22 has a trap site trapping the charge in the film. The threshold of the memory cell MC changes due to the presence/absence and amount of the charge trapped in the trap site. Thereby, the memory cell MC retains information. - The
oxide film 23 a is provided around thecharge storage film 22. For example, theoxide film 23 a contains silicon oxide (SiO2). When forming the electrode layers (SGS, WL, SGD), theoxide film 23 a protects, for example, thecharge storage film 22 from etching. Thememory film 24 is composed of the tunneling insulatingfilm 21, thecharge storage film 22, and theoxide film 23 a. - An
oxide film 23 c is provided around theoxide film 23 a. Also, theoxide film 23 c is provided between each of the electrode layers (SGS, WL, SGD) and the insulatinglayer 40. For example, theoxide film 23 c contains aluminum oxide (Al2O3). A blocking insulatingfilm 23 is composed of theoxide film 23 a and theoxide film 23 c. - The insulating
layer 42 is provided on the columnar portion CL and the insulatinglayer 41. The insulatinglayer 43 is provided on the insulatinglayer 42. The insulatinglayer 42 and the insulatinglayer 43 contain, for example, silicon oxide. Thecontact portion 30 is located in the insulatinglayer 42 and the insulatinglayer 43. A top end of thecontact portion 30 is connected to the bit line BL, and a bottom end of thecontact portion 30 is connected to theplug portion 32. - The insulating
film 19 is provided in the slit ST. The insulatingfilm 19 is provided at the sidewall of theinterconnect portion 18 and extends in the Z-direction and the X-direction. The insulatingfilm 19 contains, for example, silicon oxide. The insulatingfilm 19 electrically insulates theinterconnect portion 18 and each of the electrode layers (SGS, WL, SGD) of the stackedbody 15. - A plate portion PT is composed of the
interconnect portion 18 and the insulatingfilm 19. The plate portion PT penetrates the insulatinglayer 42, the insulatinglayer 41, and thestacked body 15, and a bottom end of the plate portion PT is contact with thesubstrate 10. -
FIG. 3 is an enlarged plan view extracting one portion of the word line WL between the slits ST.FIG. 4 is an enlarged view of an area A ofFIG. 2 , and is a view including an area corresponding to the Y-Z cross-section by the A1-A2 line ofFIG. 3 . - As shown in
FIG. 3 , theinterconnect portion 18A, the insulating film 19A1, and the insulating film 19A2 extending in X-direction are provided in the slit ST1. The plate portion PT1 is composed of theinterconnect portion 18A, the insulating film 19A1, and the insulating film 19A2. Theinterconnect portion 18B, the insulating film 19B1, and the insulating film 19B2 extending in the X-direction are provided in the slit ST2. The plate portion PT2 is composed of theinterconnect portion 18B, the insulating film 1961, and the insulating film 1962. - As viewed in the Z-direction, the plurality of columnar portions CL is disposed in a staggered lattice configuration between the slit ST1 and the slit ST2. The columnar portions CL1 a, CL1 b, CL2 a, CL2 b, CL3 a, CL3 b, CL4 a, CL4 b are disposed in the word line WL.
- If a virtual straight line along the X-direction has been set on the word line WL, the columnar portion CL1 a and the columnar portion CL1 b are located on the same straight line. Further, if a virtual straight line along the X-direction has been set on the word line WL, the columnar portion CL2 a and the columnar portion CL2 b, the columnar portion CL3 a and the columnar portion CL3 b, and the columnar portion CL4 a and the columnar portion CL4 b are located on the same straight line, respectively. Here, the number of the columnar portions CL is arbitrary.
- If a straight line DC is the reference, the columnar portions CL1 a, CL1 b, CL2 a, CL2 b are disposed at the slit ST1 side of the word line WL, and the columnar portions CL3 a, CL3 b, CL4 a, CL4 b are disposed at the slit ST2 side of the word line WL. The straight line DC is a virtual straight line which is set along the X-direction on the word line WL; and when the width of the word line WL in the Y-direction is represented by W1, the straight line DC is the straight line located at a distance of W1/2 in Y-direction from the slit ST1 and the slit ST2.
- Among the columnar portions CL1 a, CL1 b, CL2 a, CL2 b disposed at the slit ST1 side, distances in the Y-direction between the columnar portion CLla and the slit ST1 and between the columnar portion CL1 b and the slit ST1 are short as compared with distances in the Y-direction between the columnar portion CL2 a and the slit ST1 and between the columnar portion CL2 b and the slit ST1. In other words, the columnar portions CL1 a, CL1 b are disposed so that the distances in the Y-direction between the columnar portion CL1 a and the slit ST1 and between the columnar portion CL1 b and the slit ST1 are the shortest distance among all the columnar portions CL.
- Among the columnar portions CL3 a, CL3 b, CL4 a, CL4 b disposed at the slit ST2 side, distances in the Y-direction between the columnar portion CL4 a and the slit ST2 and between the columnar portion CL4 b and the slit ST2 are short as compared with distances in the Y-direction between the columnar portion CL3 a and the slit ST2 and between the columnar portion CL3 b and the slit ST2. In other words, the columnar portions CL4 a, CL4 b are disposed so that the distances in the Y-direction between the columnar portion CL4 a and the slit ST2 and between the columnar portion CL4 b and the slit ST2 are the shortest distance among all the columnar portions CL.
- The columnar portions CL1 a, CL1 b, CL4 a, CL4 b are disposed so that the distance is shortest between any of the slit ST1 and the slit ST2. On the other hand, the columnar portions CL2 a, CL2 b, CL3 a, CL3 b are disposed in a central portion of the word line WL that the straight line DC is formed.
- That is, the columnar portions CL1 a, CL1 b, CL4 a, CL4 b are disposed at the outside of the word line WL, and the columnar portions CL2 a, CL2 b, CL3 a, CL3 b are disposed at the inside of the word line WL. In this case, the columnar portions CL1 a, CL1 b, CL4 a, CL4 b are disposed at the outside of the insulating
layer 40, and the columnar portions CL2 a, CL2 b, CL3 a, CL3 b are disposed at the inside of the insulatinglayer 40. - The distance between the slit ST and the columnar portion CL disposed at the outside of the word line WL is shorter as compared with the distance between the slit ST and the columnar portion CL disposed at the inside of the word line WL. For example, a distance d1 in the Y-direction between the slit ST1 and the columnar portion CL1 b disposed at the outside of the word line WL is smaller than a distance d2 in the Y-direction between the slit ST2 and the columnar portion CL3 b disposed at the inside of the word line WL. The distance d1 is a distance between the columnar portion CL1 b and an end portion t1 of the word line WL, and the distance d2 is a distance between the columnar portion CL3 b and an end portion t2 of the word line WL.
- Hereinafter, the columnar portions CL which are disposed at the outside and the inside of the word line WL, respectively will now be described.
- As shown in
FIG. 4 , the columnar portions CL1 b, CL3 b are located in the word line WL. - In the columnar portion CL1 b which is located in the word line WL, the
oxide film 23 a 1 has an oxide portion 23 b 1 provided around the charge storage film 22 a 1. The oxide portion 23 b 1 overlaps with a part of the charge storage film 22 a 1 of the columnar portion CL1 b which is located in the insulatinglayer 40, as viewed in the Z-direction. - In the columnar portion CL3 b which is located in the word line WL, the
oxide film 23 a 2 has an oxide portion 23b 2 provided around the charge storage film 22 a 2. The oxide portion 23b 2 overlaps with a part of the charge storage film 22 a 2 of the columnar portion CL3 b which is located in the insulatinglayer 40, as viewed in the Z-direction. - The oxide portion 23 b 1 is a portion which is formed by oxidizing a part of the charge storage film 22 a 1 of the columnar portion CL1 b located in the word line WL. The oxide portion 23
b 2 is a portion which is formed by oxidizing a part of the charge storage film 22 a 2 of the columnar portion CL3 b located in the word line WL. If the charge storage films 22 a 1, 22 a 2 are formed by silicon nitride, the oxide portions 23 b 1, 23b 2 are, for example, formed by radical oxidizing of the silicon nitride. - In the columnar portions CL1 b, CL3 b located in the same word line WL, a width W2 of the oxide portion 23 b 1 of the columnar portion CL1 b is greater than a width W3 of the oxide portion 23
b 2 of the columnar portion CL3 b. Further, a width W4 of the charge storage film 22 a 1 of the columnar portion CL1 b is smaller than a width W5 of the charge storage film 22 a 2 of the columnar portion CL3 b. The width W4 and the width W5 may be thicknesses capable of storing charges in the charge storage films 22 a 1, 22 a 2, and the thicknesses are, for example, 5 nanometers or more. Further, a width W6 of theoxide film 23 a 1 of the columnar portion CL1 b is a width W7 of theoxide film 23 a 2 of the columnar portion CL3 b or less. For example, the width W6 and the width W7 will be approximately the same. - Here, in the specification, “the columnar portions CL are located in the same word line WL” refers to the columnar portions CL are located in one of the same word line WL which extends in the X-direction in the stacked
body 15. - For example, in the columnar portion CL1 b located in the different word lines WL, widths of the charge storage film 22 a 1 of the columnar portion CL1 b will be approximately the same. Further, widths of the
oxide film 23 a 1 of the columnar portion CL1 b will be approximately the same. - For example, in the columnar portion CL3 b located in the different word lines WL, widths of the charge storage film 22 a 2 of the columnar portion CL3 b will be approximately the same. Further, widths of the
oxide film 23 a 2 of the columnar portion CL3 b will be approximately the same. - Hereinafter, a method for manufacturing the semiconductor memory device according to the first embodiment will now be described.
-
FIG. 5 toFIG. 12 are cross-sectional views showing a manufacturing method of the semiconductor memory device of the first embodiment. - First, a flow of the manufacturing method of the semiconductor memory device 1 will be briefly described with reference to
FIG. 5 toFIG. 9 .FIG. 5 toFIG. 8 are cross-sectional views showing a manufacturing process of a region shown inFIG. 2 , and show a portion lower than the insulatinglayer 43.FIG. 9 is an enlarged view of a region “B” shown inFIG. 8 . - First, as shown
FIG. 5 , the insulatinglayer 40 and thesacrificial layer 50 are alternately stacked on thesubstrate 10 along the Z-direction by, for example, CVD (Chemical Vapor Deposition) method to form astacked body 15 a. For example, the insulatinglayer 40 is formed using silicon oxide. Thesacrificial layer 50 is formed using a material, which may be takes an etching selectivity ratio with respect to the insulatinglayer 40, and is formed using silicon nitride, for example. After that, the insulatinglayer 41 is formed on thestacked body 15 a. - Continuously, a plurality of memory holes 51 (through holes) is formed in the insulating
layer 41 and thestacked body 15 a by, for example, RIE (Reactive Ion Etching). Thememory holes 51 extend in the Z-direction, pierce the insulatinglayer 41 and thestacked body 15 a, and reach thesubstrate 10. For example, as viewed in the Z-direction, thememory holes 51 having a circular shape are disposed in a staggered configuration. - Then, as shown
FIG. 6 , by, for example, CVD method, silicon oxide is deposited on an inner surface of thememory hole 51 to form anoxide film 23A, silicon nitride is deposited to form anitride film 22A, and silicon oxide is deposited to form the tunneling insulatingfilm 21. After that, the tunneling insulatingfilm 21, thenitride film 22A, and theoxide film 23A are removed from a bottom surface of thememory hole 51 by performing RIE to expose thesubstrate 10. After that, thesemiconductor body 20 is formed by depositing silicon, and thecore portion 60 is formed by depositing silicon oxide. Thesemiconductor body 20 is contact with thesubstrate 10. After that, theplug portion 32 is formed by removing an upper portion of thecore portion 60 using etch back, and embedding silicon that impurities are doped. After that, the insulatinglayer 42 is formed on the insulatinglayer 41. - Then, as shown
FIG. 7 , a plurality of slits ST1, ST2 extending in the X-direction are formed in the stackedbody 15 a by, for example, anisotropic etching such as RIE. The slits ST1, ST2 are caused to pierce the insulatinglayer 42, the insulatinglayer 41, and thestacked body 15 a. Thereby, thestacked body 15 a is divided into a plurality of stacked bodies extending in the X-direction by the slits ST1, ST2. - Further, by forming the slits ST1, ST2, one of the memory holes 51 (the
memory hole 51A) shown inFIG. 7 is disposed at outsides of the insulatinglayer 40 and thesacrificial layer 50, and the other of the memory holes 51 (thememory hole 51B) shown inFIG. 7 is disposed at insides of the insulatinglayer 40 and thesacrificial layer 50. The nitride film 22A1 and the oxide film 23A1 are formed in thememory hole 51A, and the nitride film 22A2 and the oxide film 23A2 are formed in thememory hole 51B. - Then, as shown
FIG. 8 , thesacrificial layers 50 are removed by performing wet etching via the slits ST1, ST2. If thesacrificial layers 50 are formed by silicon nitride, phosphoric acid is used as an etchant of the wet etching, and the processing is performed using hot phosphoric acid. By removing thesacrificial layers 50 via the slits ST1, ST2,spaces 53 are formed. - Further, as shown
FIG. 9 , in thespaces 53 that positions in the Z-direction are same, a width Wa1 of the oxide film 23A1 of thememory hole 51A is smaller than a width Wa2 of the oxide film 23A2 of thememory hole 51B. A distance d3 between the slit ST1 and thememory hole 51A is smaller than a distance d4 between the slit ST2 and thememory hole 51B. Therefore, when removing thesacrificial layers 50, the oxide film 23A1 is in contact with hot phosphoric acid long time as compared with the oxide film 23A2. If a time of the oxide film 23A1 exposed to hot phosphoric acid is longer than a time of the oxide film 23A2 exposed to hot phosphoric acid, the oxide film 23A1 is further etched by hot phosphoric acid, and the film thickness of the oxide film 23A1 is smaller than the film thickness of the oxide film 23A2. - The above is a simplified flow of a manufacturing method of the semiconductor memory device 1, but in the embodiment, the formation of the
oxide film 23 a, theoxide film 23 c, and the electrode layers (SGS, WL, SGD) are performed as follows. About this process will be described with reference toFIG. 10 toFIG. 12 . Here, cross-sections shown inFIG. 10 toFIG. 12 correspond to the cross-section shown inFIG. 9 . - After the steps shown in
FIG. 8 andFIG. 9 , as shown inFIG. 10 , radical oxidation process is performed to the nitride films 22A1, 22A2 via the slits ST1, ST2, and thespaces 53. A part of the nitride film 22A1 is oxidized via the oxide film 23A1 in thememory hole 51A, and a part of the nitride film 22A2 is oxidized via the oxide film 23A2 in thememory hole 51B. Further, by the radical oxidation process, side surfaces of the oxide films 23A1, 23A2 are expanded to both side of the Y-direction. - Thereby, the charge storage film 22 a 1 and the
oxide film 23 a 1 are formed in thememory hole 51A, and the charge storage film 22 a 2 and theoxide film 23 a 2 are formed in thememory hole 51B. Theoxide films 23 a 1, 23 a 2 have the oxide portions 23 b 1, 23b 2, respectively. Since the width of the oxide film 23A1 is smaller than the width of the oxide film 23A2, the nitride film 22A1 is easily oxidized than the nitride film 22A2. Therefore, the width W2 of the oxide portion 23 b 1 is greater than the width W3 of the oxide portion 23b 2. - Further, the columnar portion CLA is formed in the
memory hole 51A, and includes thecore portion 60, thesemiconductor body 20, the tunneling insulatingfilm 21, the charge storage film 22 a 1, and theoxide film 23 a 1. The columnar portion CLB is formed in thememory hole 51B, and includes thecore portion 60, thesemiconductor body 20, the tunneling insulatingfilm 21, the charge storage film 22 a 2, and theoxide film 23 a 2. The columnar portion CLA is disposed at the outside of the insulatinglayer 40, and the columnar portion CLB is disposed at the inside of the insulatinglayer 40. For example, the columnar portion CLA corresponds to any of the columnar portions CL1 a, CL1 b, CL4 a, CL4 b as shown inFIG. 3 . The columnar portion CLB corresponds to any of the columnar portions CL2 a, CL2 b, CL3 a, CL3 b as shown inFIG. 3 . - Then, as shown in
FIG. 11 , theoxide film 23 c is formed by depositing aluminum oxide on an entire surface, for example, using CVD method. Theoxide film 23 c is formed around theoxide films 23 a 1, 23 a 2 and on the insulatinglayer 40. Thereby, the blocking insulatingfilm 23 is formed. - Here, the radical oxidation process of the nitride films 22A1, 22A2 shown in
FIG. 10 may be performed after forming theoxide film 23 c. In this case, a part of the nitride film 22A1 is oxidized via theoxide film 23 c and the oxide film 23A1 in thememory hole 51A, and a part of the nitride film 22A2 is oxidized via theoxide film 23 c and the oxide film 23A2 in thememory hole 51B. - Then, as shown in
FIG. 12 , conductive layers are formed on an entire surface by, for example, CVD method. The conductive layer also enters an interior of thespace 53 via the slits ST1, ST2. After that, the conductive layers are etched by isotropic etching such as CDE (Chemical Dry Etching) or wet etching so as not to short the adjacent conductive layers in the Z-direction. Thereby, the source-side select gate SGS, the drain-side select gate SGD, and the plurality of word lines WL are formed. Thestacked body 15 including the electrode layers (SGS, WL, SGD) and the plurality of insulatinglayers 40 is formed. - In the columnar portions CLA, CLB located in the same word line WL, the width W4 of the charge storage films 22 a 1 of the columnar portion CLA is smaller than the width W5 of the charge storage film 22 a 2 of the columnar portion CLB. The width W6 of the
oxide film 23 a 1 of the columnar portion CLA is the width W7 of theoxide film 23 a 2 of the columnar portion CLB or less. - After that, after depositing silicon oxide on the entire surface, an insulating film is etched back to leave on side surfaces of the slits ST1, ST2, thereby forming the insulating
films 19. Continuously, metal such as tungsten is deposited in the slits ST1, ST2 to form theinterconnect portions 18. - In this way, the semiconductor device 1 according to the first embodiment is manufactured.
- Hereinafter, an effect of the first embodiment is described.
- In the semiconductor memory device having a three-dimensional structure, when forming the slits and the memory holes in the stacked body, a plurality of memory holes sometimes is disposed such that the difference in distance between the slit occurs. In this arrangement of the memory holes, when removing the sacrificial layer using hot phosphoric acid, the oxide film formed in the memory hole having a short distance from the slit is in contact long to hot phosphoric acid as compared to the oxide film formed in the memory hole having a long distance from the slit. The oxide film exposed to hot phosphoric acid for a long period of time is easily etched by hot phosphoric acid. Thereby, there is a possibility that variation arises in the thickness of the oxide film formed in each memory hole depending on the distance between the memory hole and the slit.
- In the semiconductor memory device 1 of the embodiment, in the same word line WL, the width of the
charge storage film 22 of the columnar portion CL disposed at the outside of the word line WL is smaller than the width of thecharge storage film 22 of the columnar portion CL disposed at the inside of the word line WL. Further, the width of theoxide film 23 a of the columnar portion CL disposed at the outside of the word line WL is the width of theoxide film 23 a of the columnar portion CL disposed at the inside of the word line WL or less. - When the plurality of columnar portions CL is disposed in this manner, it is possible to reduce the difference of the widths of the
oxide films 23 a in the same word line WL. Since uniformity of a width of eachoxide film 23 a can be ensured, it is possible to suppress the moving of the charge in thecharge storage film 22 via theoxide film 23 a having a thin thickness. In other words, since leak currents via theoxide film 23 a can be suppressed, charge retention characteristic of thecharge storage film 22 is improved. - Further, since the uniformity of the width of each
oxide film 23 a can be ensured, for example, when the charge is moved from thesemiconductor body 20 to the charge storage film 22 (programming operation), it is possible to reduce variation of a programming speed of the memory cell MC. Therefore, an operating characteristic of the memory cell MC can be improved. -
FIG. 13 is an enlarge plan view extracting one portion of the word line WL between the slits ST.FIG. 14 is the Y-Z cross-sectional view by the B1-B2 line ofFIG. 13 . - The embodiment and the first embodiment are different in the arrangement of the columnar portions CL in the word line WL. Since structure except for the arrangement of the columnar portions CL is same as the first embodiment, detailed description of the other structure is omitted.
- As shown in
FIG. 13 , the plurality of columnar portions CL is disposed in a staggered lattice configuration between the slit ST1 and the slit ST2. As viewed in the Z-direction, the columnar portions CL1 a, CL1 b, CL2 a, CL2 b, CL3 a, CL3 b, CL4 a, CL4 b, CL5 a, CL5 b, CL6 a, CL6 b are disposed in the word line WL. If a virtual straight line along the X-direction has been set on the word line WL, the columnar portion CL1 a and the columnar portion CL1 b are located on the same straight line. Further, if a virtual straight line along the X-direction has been set on the word line WL, the columnar portion CL2 a and the columnar portion CL2 b, the columnar portion CL3 a and the columnar portion CL3 b, the columnar portion CL4 a and the columnar portion CL4 b, the columnar portion CL5 a and the columnar portion CL5 b, and the columnar portion CL6 a and the columnar portion CL6 b are located on the same straight line, respectively. - The columnar portions CL1 a, CL1 b, CL2 a, CL2 b are disposed at the slit ST1 side of the word line WL, and the columnar portions CL3 a, CL3 b, CL4 a, CL4 b are disposed at the slit ST2 side of the word line WL.
- The columnar portion CL5 a is located between the columnar portion CL1 a and the columnar portion CL3 a, and the columnar portion CL5 b is located between the columnar portion CL1 b and the columnar portion CL3 b. The columnar portion CL6 a is located between the columnar portion CL2 a and the columnar portion CL4 a, and the columnar portion CL6 b is located between the columnar portion CL2 b and the columnar portion CL4 b.
- The columnar portions CL1 a, CL1 b are disposed so that the distances between the columnar portion CL1 a and the slit ST1 and between the columnar portion CL1 b and the slit ST1 are the shortest distance among all the columnar portions CL. The columnar portions CL4 a, CL4 b are disposed so that the distances between the columnar portion CL4 a and the slit ST2 and between the columnar portion CL4 b and the slit ST2 are the shortest distance among all the columnar portions CL.
- The columnar portions CL2 a, CL2 b are disposed so that the distances between the columnar portion CL2 a and the slit ST1 and between the columnar portion CL2 b and the slit ST1 are short as compared with distances between the columnar portion CL6 a and the slit ST1 and between the columnar portion CL6 b and the slit ST1.
- The columnar portions CL3 a, CL3 b are disposed so that the distances between the columnar portion CL3 a and the slit ST2 and between the columnar portion CL3 b and the slit ST2 are short as compared with distances between the columnar portion CL5 a and the slit ST2 and between the columnar portion CL5 b and the slit ST2.
- The columnar portions CL1 a, CL1 b, CL2 a, CL2 b, CL3 a, CL3 b, CL4 a, CL4 b are disposed at the outside of the word line WL, and the columnar portions CL5 a, CL5 b, CL6 a, CL6 b are disposed at the inside of the word line WL.
- Hereinafter, the columnar portions CL which are disposed at the outside and the inside of the word line WL, respectively will now be described.
- As shown in
FIG. 14 , the columnar portions CL1 b, CL3 b, CL5 b are located in the word line WL. - In the columnar portion CL1 b which is located in the word line WL, the
oxide film 23 a 1 has the oxide portion 23 b 1 provided around the charge storage film 22 a 1. As viewed in the Z-direction, the oxide portion 23 b 1 overlaps with a part of the charge storage film 22 a 1 of the columnar portion CL1 b which is located in the insulatinglayer 40. - In the columnar portion CL3 b which is located in the word line WL, the
oxide film 23 a 2 has the oxide portion 23b 2 provided around the charge storage film 22 a 2. As viewed in the Z-direction, the oxide portion 23b 2 overlaps with a part of the charge storage film 22 a 2 of the columnar portion CL3 b which is located in the insulatinglayer 40. - In the columnar portion CL5 b which is located in the word line WL, the
oxide film 23 a 3 has the oxide portion 23 b 3 provided around the charge storage film 22 a 3. As viewed in the Z-direction, the oxide portion 23 b 3 overlaps with a part of the charge storage film 22 a 3 of the columnar portion CL5 b which is located in the insulatinglayer 40. - In the columnar portions CL1 b, CL3 b, CL5 b located in the same word line WL, the width W2 of the oxide portion 23 b 1 of the columnar portion CL1 b is greater than the width W3 of the oxide portion 23
b 2 of the columnar portion CL3 b. The width W3 is greater than a width W8 of the oxide portion 23 b 3 of the columnar portion CL5 b. - Further, the width W4 of the charge storage film 22 a 1 of the columnar portion CL1 b is smaller than the width W5 of the charge storage film 22 a 2 of the columnar portion CL3 b. The width W5 is smaller than a width W9 of the charge storage film 22 a 3 of the columnar portion CL5 b. The width W4, the width W5, and the width W9 are, for example, 5 nanometers or more.
- Further, the width W6 of the
oxide film 23 a 1 of the columnar portion CL1 b is the width W7 of theoxide film 23 a 2 of the columnar portion CL3 b or less. The width W7 is a width W10 of theoxide film 23 a 3 of the columnar portion CL5 b or less. For example, the width W6, the width W7, and thewidth 10 will be approximately the same. - Hereinafter, an effect of the second embodiment is described.
- In the semiconductor memory device 1 of the embodiment, in the same word line WL, the width of the
charge storage film 22 of the columnar portion CL disposed at the outside of the word line WL is smaller than the width of thecharge storage film 22 of the columnar portion CL disposed at the inside of the word line WL. Further, in the plurality of columnar portions CL disposed at the outside of the word line WL, the width of thecharge storage film 22 of the columnar portion CL having a short distance between the slit ST and the columnar portion CL is smaller than the width of thecharge storage film 22 of the columnar portion CL having a long distance between the slit ST and the columnar portion CL. - Furthermore, the width of the
oxide film 23 a of the columnar portion CL disposed at the outside of the word line WL is the width of theoxide film 23 a of the columnar portion CL disposed at the inside of the word line WL or less. In addition, in the plurality of columnar portions CL disposed at the outside of the word line WL, the width of theoxide film 23 a of the columnar portion CL having a short distance between the slit ST and the columnar portion CL is the width of theoxide film 23 a of the columnar portion CL having a long distance between the slit ST and the columnar portion CL or less. - When the plurality of columnar portions CL is disposed in this manner, it is possible to reduce the difference of the widths of the
oxide films 23 a in the same word line WL. Thereby, it is possible to ensure the uniformity of the width of eachoxide film 23 a and suppress the reducing of the charge retention characteristic of thecharge storage film 22 of each memory cell MC. Further, since the programming speed of the memory cell MC is increased, the operating characteristic of the memory cell MC is improved. - Therefore, the failure of operation of the memory cell MC can be suppressed.
- In the first embodiment and the second embodiment, although two or three columnar portions CL are disposed in the word line WL in the Y-direction, the number of the columnar portions CL and the arrangement of the columnar portions CL are arbitrary. For example, any number of the columnar portions CL may be disposed in the word line WL in the Y-direction.
- While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modification as would fall within the scope and spirit of the inventions.
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