This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2022-044447 filed on Mar. 18, 2022; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a semiconductor storage device and a method of manufacturing the same.
Faster access performance is requested for a semiconductor storage device.
A semiconductor storage device according to an embodiment includes: a substrate; a circuit provided on the substrate; a plurality of first electrodes provided above the substrate and connected to the circuit through a plurality of first contacts; a plurality of second electrodes connected to the plurality of first electrodes; a memory cell array connected to the plurality of second electrodes through a plurality of second contacts, the memory cell array including a block, the block including a plurality of units, each of the units including a plurality of memory cell transistors and a plurality of first column-shaped parts, the plurality of first column-shaped parts penetrating through at least one stack body that is a stack of a plurality of electrode layers between which an insulating layer is interposed; a first source region provided above the memory cell array and electrically connected to a portion of the plurality of memory cell transistors; a second source region provided above the memory cell array and electrically connected to another portion of the plurality of memory cell transistors; and a first slit insulating the first source region and the second source region for each of the units.
Embodiments will be described below with reference to the accompanying drawings.
The memory controller 10 is connected to the semiconductor storage device 1 through a NAND bus. The NAND bus performs signal transmission and reception in accordance with a NAND interface. The memory controller 10 controls the semiconductor storage device 1.
Signals transmitted and received between the memory controller 10 and the semiconductor storage device 1 through the NAND bus include a chip enable signal CEn, a command latch enable signal CLE, an address latch enable signal ALE, a write enable signal WEn, a read enable signal REn, a ready/busy signal RBn, and input-output signals I/O.
The memory controller 10 is connected to a non-illustrated host device. The memory controller 10 accesses the semiconductor storage device 1 in response to a request received from the host device.
The semiconductor storage device 1 is a NAND flash memory. The semiconductor storage device 1 includes a memory cell array 110 and a peripheral circuit. The peripheral circuit includes a row decoder 120, a driver 130, a column decoder 140, an address register 150, a command register 160, and a sequencer 170.
The memory cell array 110 includes a plurality of memory cells. Each memory cell can store data of one bit or a plurality of bits in a non-volatile manner.
The memory cell array 110 includes a plurality of blocks BLK. The memory cell array 110 is a NAND memory cell array having a three-dimensional structure.
Each block BLK includes a plurality of non-volatile memory cells associated with rows and columns. Four blocks BLK0 to BLK3 are illustrated in
The sequencer 170 controls operation of the entire semiconductor storage device 1 based on a command CMD temporarily stored in the command register 160.
As illustrated, one block BLK includes, for example, four string units SU0 to SU3. Each string unit SU includes a plurality of NAND strings NS. In this example, each of the plurality of NAND strings NS includes eight memory cells MT (MT0 to MT7) and selection transistors ST1 and ST2. Note that the number of memory cells MT included in each NAND string NS is eight in this example but not limited to eight, and may be, for example, 32, 48, 64, 96, or more. The selection transistors ST1 and ST2 are each indicated as one transistor in electric circuit but may be each a memory cell transistor in structure. In this example, a plurality of selection transistors are used as each of the selection transistors ST1 and ST2 to increase a cutoff characteristic.
The memory cells MT are disposed between the selection transistors ST1 and ST2 and connected in series. The memory cell MT7 on one end side is connected to the selection transistor ST1, and the memory cell MT0 on the other end side is connected to the selection transistor ST2.
Gates of the selection transistors ST1 of the string units SU0 to SU3 are connected to selection gate lines SGD0 to SGD3, respectively. Voltages of the selection gate lines SGD0 to SGD3 can be each independently controlled by the sequencer 170.
Gates of the selection transistors ST2 of the string units SU0 to SU3 are connected to selection gate lines SGS0 to SGS3, respectively. Voltages of the selection gate lines SGS0 to SGS3 can be each independently controlled by the sequencer 170. The selection transistor ST2 are selection gates for selecting the plurality of string units SU in the block BLK. A plurality of voltages different from one another can be supplied to the gates of the plurality of selection transistors ST2.
The sources of the selection transistors ST2 of the string units SU0 to SU3 are connected to source lines SL0 to SL3, respectively. Voltages of the source lines SL0 to SL3 can be each independently controlled by the sequencer 170.
Gates of the memory cells MT0 to MT7 in the same block BLK are connected in common to word lines WL0 to WL7, respectively. In other words, gates of memory cells MTi on the same row in the block BLK are connected to the same word line WLi.
In other words, in the same block BLK, the word lines WL0 to WL7 are connected in common among the string units SU0 to SU3, but the selection gate lines SGD0 to SGD3 and SGS0 to SGS3 are independent among the string units SU0 to SU3 in the same block BLK.
Each NAND string NS is connected to a corresponding bit line BL. Thus, each memory cell MT is connected to the bit line BL through the selection transistor ST1, or any other memory cell MT in some cases, included in the NAND string NS.
Data of the memory cells MT in the same block BLK is deleted all at once. Data reading and writing are performed for each a memory cell group MG.
Note that each memory cell MT may be a single level cell (SLC) that can store one bit data or may be a memory cell that can store data of multiple-value bits such as two bits or three bits.
In
The surface of the memory chip 2 on which the plurality of bonding electrodes P1 are provided is referred to as a front surface, and the surface of the memory chip 2 on which the plurality of bonding pad electrodes PX are provided is referred to as a back surface. The surface of the controller chip 3 on which the plurality of bonding electrodes P2 are provided is referred to as a front surface, and a surface opposite the front surface is referred to as a back surface. In the illustrated example, the front surface of the controller chip 3 is provided higher than the back surface of the controller chip 3, and the back surface of the memory chip 2 is provided higher than the front surface of the memory chip 2.
In the semiconductor storage device 1, the front surface of the memory chip 2 and the front surface of the controller chip 3 are oppositely disposed and bonded to each other. The plurality of bonding electrodes P1 are provided in correspondence with the plurality of respective bonding electrodes P2 and disposed at positions where the plurality of bonding electrodes P1 can be bonded to the plurality of bonding electrodes P2. The bonding electrodes P1 and P2 function as electrodes for bonding and electrically connecting the memory chip 2 and the controller chip 3 to each other. The bonding pad electrodes PX function as electrodes for electrically connecting the semiconductor storage device 1 to, for example, a non-illustrated substrate.
In
In the following description, the stacking direction of a stack body 20 to be described later is defined as a Z direction. One direction intersecting, for example, orthogonal to the Z direction is defined as a Y direction. One direction orthogonal to the Z and Y directions is defined as an X direction.
As illustrated in
The controller chip 3 includes a substrate 11, a processing circuit 12, vias 13, wires 14, the bonding electrodes P2, and an interlayer insulating film 15.
The substrate 11 is, for example, a semiconductor substrate such as silicon substrate. The processing circuit 12 includes a transistor provided on the substrate 11. The processing circuit 12 may include, in addition to the transistor, elements such as a resistance element and a capacitor element provided on the substrate 11.
The vias 13 electrically connect the processing circuit 12 and the wires 14 and electrically connect the wires 14 and the bonding electrodes P2. The wires 14 and the bonding electrodes P2 form a multi-layer wiring structure in the interlayer insulating film 15. The bonding electrodes P2 are embedded in the interlayer insulating film 15. At least a portion of a front surface of each bonding electrode P2 is exposed to be substantially flush with a front surface of the interlayer insulating film 15. The wires 14 and the bonding electrodes P2 are electrically connected to the processing circuit 12 and the like. The vias 13, the wires 14, and the bonding electrodes P2 are made of a low resistance metal such as copper or tungsten. The interlayer insulating film 15 covers and protects the processing circuit 12, the vias 13, and the wires 14. The interlayer insulating film 15 is an insulating film such as a silicon oxide film.
The memory chip 2 includes the stack body 20, column-shaped parts CL, slits ST, a source layer BSL, an interlayer insulating film 21, contacts 22, an insulating film 23, wires 24, and an insulating film 25.
The stack body 20 is provided above the processing circuit 12 and positioned in the Z direction relative to the substrate 11. The stack body 20 includes a plurality of electrode films 20a and a plurality of insulating films 20b that are alternately stacked in the Z direction. The electrode films 20a are made of a conductive metal such as tungsten. The insulating films 20b are made of, for example, silicon oxide. The insulating films 20b insulate the electrode films 20a from each other. In other words, the electrode films 20a are stacked in a mutually insulated state. The number of stacked electrode films 20a and the number of stacked insulating films 20b are optional. The insulating films 20b may be each, for example, a porous insulating film or an air gap.
In
One or a plurality of electrode films 20a at each of the upper and lower ends of the stack body 20 in the Z direction function as a source-side selection gate SGS or a drain-side selection gate SGD. At least a portion of electrode films 20a between the source-side selection gate SGS and the drain-side selection gate SGD function as word lines WL. Each word line WL is agate electrode of a memory cell MT. The drain-side selection gate SGD is a gate electrode of a drain-side selection transistor. The source-side selection gate SGS is a gate electrode of a source-side selection transistor. The source-side selection gate SGS is provided in an upper region of the stack body 20. The drain-side selection gate SGD is provided in a lower region of the stack body 20. The lower region is a region of the stack body 20 on a side closer to the controller chip 3, and the upper region is a region of the stack body 20 on a side farther from the controller chip 3 (side closer to the contacts 22 and the insulating film 25).
As described above, the semiconductor storage device 1 includes a plurality of memory cells MT connected in series between the source-side selection transistor ST2 and the drain-side selection transistor ST1. Each NAND string NS has a structure in which the source-side selection transistor ST2, the memory cells MT, and the drain-side selection transistor ST1 are connected in series. The NAND string NS is connected to a bit line BL through, for example, a via 26. The bit lines BL are a plurality of wires 27 provided below the stack body 20, each extending in the X direction, and provided alongside in the Y direction.
The plurality of column-shaped parts CL are provided in the stack body 20. In the stack body 20, the column-shaped parts CL extend and penetrate through the stack body 20 in the stacking direction of the stack body 20 (the Z direction) and are provided from the via 26 connected to the bit lines BL to the source layer BSL. In the present embodiment, each column-shaped part CL has a high aspect ratio and thus is formed as two divided parts in the Z direction. However, the column-shaped part CL may be a single part. The source-side selection transistor ST2 and the drain-side selection transistor ST1 include part of a column-shaped part CL.
The semiconductor body MB is electrically connected to the source layer BSL. The memory film MM is provided between the semiconductor body MB and each electrode film 20a and includes an electric charge capturing part. The shape of the memory hole MH on an XY plane is, for example, a circle or an ellipse.
As illustrated in
The plurality of slits ST are provided in the stack body 20. The slits ST extend in the X direction and penetrate through the stack body 20 in the stacking direction of the stack body 20 (the Z direction). Each slit ST is filled with an insulation material such as silicon oxide, and the insulation material is formed in a plate shape. The stack body 20 is divided in the blocks BLK by the slits ST. The slits ST electrically divide the electrode films 20a of the stack body 20. The plurality of slits ST are formed such that one block BLK is sandwiched between two adjacent slits ST.
A plurality of string units SU are provided between two adjacent slits ST. In this example, the four string units SU0 to SU3 are provided between two adjacent slits ST as illustrated in
A plurality of column-shaped parts CL (hereinafter referred to as dummy column-shaped parts CL) that are dummies and do not function as string units SU are formed in the X direction between two adjacent string units SU.
A slit SHE is provided in a lower region of each dummy column-shaped part CL. The slit SHE is formed from a lower surface of the stack body 20 to the drain-side selection gate SGD of the stack body 20. The slit SHE is formed by using, for example, a lithography technology and a reactive ion etching (RIE) method. The slit SHE is filled with an insulation material such as silicon oxide, and the insulation material is formed in a plate shape. The slit SHE extends in the X direction and has a function to separate the drain-side selection gates SGD of two adjacent string units.
A slit STA extends in the X direction and penetrates through the source layer BSL above a slit ST and an upper region of the slit ST. The slit STA is filled with an insulation material such as silicon oxide, and the insulation material is formed in a plate shape. The slit STA divides the source layer BSL in the Z direction. The slit STA is provided along the slit ST when the semiconductor storage device 1 is viewed in a direction orthogonal to an XY plane.
A slit STB extends in the X direction and penetrates through a source-side selection gate SGS part of each dummy column-shaped part CL at which the source layer BSL and the slit SHE are provided. The slit STB is filled with an insulation material such as silicon oxide, and the insulation material is formed in a plate shape. In other words, the slit STB is provided above the memory cell array 110 and formed to divide the upper region of the stack body 20 in which a plurality of source-side selection gates SGS are formed. The slit STB is provided along the slit SHE when the semiconductor storage device 1 is viewed in a direction orthogonal to an XY plane.
As described above, the slits ST extend in the X direction, electrically separate the stack body 20 of the memory cell array 110 for each block BLK, and are filled with an insulation material. The slits STA extend in the X direction, separate the region of the source layer BSL for each block BLK, and are filled with an insulation material. The slits STB extend in the X direction, separate the region of the source layer BSL and the region of the source-side selection gate SGS in the stack body 20 for each string unit SU in a block BLK, and are filled with an insulation material.
Note that a plurality of column-shaped parts CL and a plurality of vias 26 in one string unit SU may be disposed in a staggered shape instead of being disposed along one line on an XY plane when the semiconductor storage device 1 is viewed from an upper surface. For example, in one string unit SU, a plurality of column-shaped parts CL and a plurality of vias 26 may be disposed in a staggered shape with four lines on an XY plane when the semiconductor storage device 1 is viewed from the upper surface.
As described above, the source layer BSL in which the source line SL is formed is divided for each string unit SU by the slit STA, the slit STB, or the slits STA and STB. Thus, the source line SL of each string unit SU is electrically connected through contacts 22 at a predetermined interval in the X direction as illustrated in
A desired source voltage can be independently supplied to each string unit SU by supplying a predetermined voltage to a wire 24. In other words, independent voltages different from each other can be supplied to a plurality of source lines SL of a plurality of string units SU.
In
Similarly to the slits SHE, the slits STA and STB are formed by using the lithography technology and the RIE method.
As described above, the semiconductor storage device 1 includes the substrate 11, a circuit (the processing circuit 12) provided on the substrate 11, the plurality of bonding electrodes P2, the plurality of bonding electrodes P1, the memory cell array 110, and the slits STA and STB. The plurality of bonding electrodes P2 are provided above the substrate 11 and connected to the circuit (processing circuit 12) through a plurality of vias 13. The plurality of bonding electrodes P1 are connected to the plurality of bonding electrodes P2. The memory cell array 110 is connected to the plurality of bonding electrodes P1 through a plurality of vias 26. The memory cell array 110 includes a block BLK including a plurality of string units SU each including a plurality of memory cell transistors. Each string unit SU includes a plurality of column-shaped parts CL penetrating through the stack body 20 that is a stack of a plurality of electrode films 20a. The slits STA and STB divide, for each string unit SU, a source region SL of the plurality of memory cell transistors provided above the memory cell array 110 and a region of a plurality of selection gates SGS of the memory cell array.
Subsequently, a method of manufacturing the semiconductor storage device 1 according to the present embodiment will be described below. (Memory chip manufacturing method)
First, as illustrated in
Subsequently, part of the conductive film 61 and part of the sacrifice film 70 are removed by using the lithography technology and an etching technology so that the conductive film 61 and the sacrifice film 70 are left over at a formation position of the source layer BSL (lower side of the stack body 20).
Subsequently, as illustrated in
Subsequently, as illustrated in
Subsequently, a stepped part 2s is formed by fabricating an end part of the stack body 20A into a stepped shape.
Subsequently, a plurality of memory holes MH penetrating through the stack body 20A in the stacking direction (Z direction) to the conductive films 61 and 62 are formed. The memory film MM, the semiconductor body MB, and the core layer MC described above are formed in each memory hole MH. Accordingly, a column-shaped part CL penetrating through the stack body 20A in the stacking direction is formed. The column-shaped part CL reaches the conductive films 61 and 62. Note that the memory hole MH and the column-shaped part CL are formed twice at upper and lower parts of the stack body 20A in the present embodiment. Note that the memory hole MH and the column-shaped part CL may be formed once for the stack body 20A.
A memory hole formed first is a memory hole (hereinafter referred to as a lower-layer memory hole) LMH formed in a lower layer of the stack body 20, and a memory hole formed next is a memory hole (hereinafter referred to as an upper-layer memory hole) UMH formed in an upper layer of the stack body 20. The stack body 20 has a lower layer region LR in which the lower-layer memory hole LMH is formed, and an upper layer region UR in which the upper-layer memory hole UMH is formed.
Subsequently, slits SHE are formed at a plurality of column-shaped parts CL (hereinafter referred to as dummy column-shaped parts) that do not function as string units SU. The slits SHE are formed by using the lithography technology and the RIE method. The slits SHE are filled with an insulation material such as silicon oxide.
Subsequently, as illustrated in
Subsequently, as illustrated in
Subsequently, the sacrifice films 29 of the stack body 20A are replaced with the electrode films 20a through the slits ST. In other words, the sacrifice films 29 are removed by etching, and a space in which the sacrifice films 29 have existed is filled with a material of the electrode films 20a. The filling material of the electrode films 20a is, for example, a low resistance metal such as tungsten. Accordingly, the stack body 20 in which the plurality of electrode films 20a and the plurality of insulating films 20b are alternately stacked is formed.
Subsequently, as illustrated in
Subsequently, as illustrated in
(Controller Chip Manufacturing Method)
First, as illustrated in
Subsequently, as illustrated in
(Bonding of Memory Chip and Controller Chip)
Subsequently, the memory chip 2 and the controller chip 3 are bonded to each other. Specifically, the memory chip 2 and the controller chip 3 are bonded such that the bonding electrodes P1 and P2 are in contact and electrically connected to each other, and the substrate 50 as the first substrate is removed.
Thereafter, as illustrated in
The slits STB penetrate through the source layer BSL and source-side selection gate SGS parts of the dummy column-shaped parts CL and each divide the source layer BSL and the source-side selection gates SGS of two adjacent string units SU for each string unit SU.
After the slits STA and STB are formed, the contacts 22, the insulating film 23, the wires 24, and the insulating film 25 are formed on the upper surface of the memory chip 2 and the bonding pad electrodes PX are lastly provided as illustrated in
(Modification of Slit ST Formation Method)
The above-described slits ST penetrate through the stack body 20 in the stacking direction of the stack body 20 (the Z direction) and are filled with an insulation material, but some slits ST may have a structure including a plurality of column-shaped parts extending in the stacking direction of the stack body 20 (the Z direction). The plurality of column-shaped parts are disposed alongside in the X direction.
In
In
First at formation of the stack body 20, the lower layer region LR including the lower-layer memory holes LMH is formed. Thereafter, the upper layer region UR including the upper-layer memory holes UMH is formed on the lower-layer memory holes LMH. In
As illustrated in
When each column-shaped part STL is formed, an inner diameter (illustrated in S3) of the column-shaped part STL at a deep part (upper part in
Thus, even when the plurality of column-shaped parts STL are formed in the X direction so that two adjacent column-shaped parts STL overlap, the two adjacent column-shaped parts STL are formed in separation from each other at a deep part in the lower layer region LR in some cases.
When two adjacent column-shaped parts STL are formed in separation from each other, a source-side selection gate SGS part at the deep part (upper part in
Thus, in the present modification, the slits STA are provided through the plurality of column-shaped parts STL at the deep part (upper part in
In other words, each slit ST includes a plate-shaped slit STU extending in the X direction in the upper layer region UR and includes a plurality of cylindrical column-shaped parts STL extending in the Z direction in the lower layer region LR. The slit ST also includes, in the lower layer region LR, a slit STA dividing a portion of the plurality of column-shaped parts STL in the X direction to divide the source-side selection gate SGS part for each block BLK. Note that
Subsequently, a semiconductor storage device manufacturing method according to the modification will be described below.
First, the lower layer region LR is formed on the substrate 50. Each lower-layer memory hole LMH is formed by using the lithography technology and the RIE method. Each lower-layer memory hole LMH is filled with an insulation material used as a sacrifice film. After the lower layer region LR is formed, the upper layer region UR is formed.
The sacrifice films 29 are replaced with a conductive film through the openings for the plate-shaped slits STU. In other words, the sacrifice films 29 is removed by etching, and a space in which the sacrifice films 29 have existed is filled with a material of the conductive film. Note that the removal of the sacrifice films 29 is performed after the insulation material as a sacrifice film filling each lower-layer memory hole LMH is removed.
Subsequently, the bit lines BL, the bonding electrodes P1, and the like are formed on the upper layer region UR.
Subsequently, the front surface of the controller chip 3 and the front surface of the memory chip 2, which are separately produced, are bonded to each other.
Subsequently, the substrate 50 of the memory chip 2 is removed.
Then, at each slit ST part, a slit STA containing an insulation material is formed in the Z direction to a depth of an SGS part of a memory hole MH.
As described above in the modification, the slits ST may be formed.
In the semiconductor storage device according to the above-described embodiment, the source layer BSL is divided between two adjacent string units SU, and the source-side selection gate SGS is divided between two adjacent string units SU.
Since the source-side selection gate SGS is divided for string unit SU, voltages supplied to a plurality of source-side selection gates SGS can be differentiated from each other. Thus, when a reading or writing voltage is supplied to a selection word line WL, a voltage of the source-side selection gate SGS or the source layer BSL of the non-selected string unit SU is controlled to put any non-selected string unit SU into a floating state, and accordingly, a voltage of a channel of the non-selected string unit in the floating state increases due to coupling between the channel of the non-selected string unit and the selection word line WL. As a result, it is possible to perform data writing and reading at high speed. Moreover, it is possible to improve program disturbance and read disturbance.
In the above-described first embodiment, the source layer BSL and each source-side selection gate SGS part are both divided between two adjacent string units SU. However, in the second embodiment, the source layer BSL may not be divided between two adjacent string units SU and each source-side selection gate SGS part may be divided between two adjacent string units SU. In the second embodiment, the source layer BSL is not divided between two adjacent string units SU, and each source-side selection gate SGS part is divided between two adjacent string units SU.
A configuration of a semiconductor storage device 1A according to the second embodiment is substantially the same as the configuration of the semiconductor storage device 1 according to the first embodiment, and thus in description below, any same constituent component in the semiconductor storage device 1A according to the second embodiment as in the semiconductor storage device 1 according to the first embodiment is denoted by, for example, the same number or reference sign, description of the constituent component is omitted, and any configuration different from in the semiconductor storage device 1 will be described.
As illustrated in
The gates of the selection transistors ST1 of the string units SU0 to SU3 are connected to the selection gate lines SGD0 to SGD3, respectively. Voltages of the selection gate lines SGD0 to SGD3 can be each independently controlled by the sequencer 170.
The gates of the selection transistors ST2 of the string units SU0 to SU3 are connected to the selection gate lines SGS0 to SGS3, respectively. Voltages of the selection gate lines SGS0 to SGS3 can be each independently controlled by the sequencer 170.
The sources of the selection transistors ST2 of the string units SU0 to SU3 are connected in common to the source line SL.
In the present embodiment, each source-side selection gate SGS part is divided between two adjacent string units SU by a slit STC. However, part of the source layer BSL, for example, the first layer BSL1 is divided between two adjacent string units SU, but the other part of the source layer BSL, for example, the second layer BSL2 is electrically connected between two adjacent string units SU.
Thus, according to the present embodiment as well, it is possible to float (in other words, boost) any non-selected string unit SU and perform data writing and reading at high speed.
In the above-described first embodiment, the source layer BSL and each source-side selection gate SGS part are both divided between two adjacent string units SU. However, in the third embodiment, each source-side selection gate SGS part may not be divided between two adjacent string units SU and the source layer BSL may be divided between two adjacent string units SU. In the third embodiment, each source-side selection gate SGS part is not divided between two adjacent string units SU, and the source layer BSL is divided between two adjacent string units SU.
A configuration of a semiconductor storage device 1B according to the third embodiment is substantially the same as the configuration of the semiconductor storage device 1 according to the first embodiment, and thus in description below, any same constituent component in the semiconductor storage device 1B according to the third embodiment as in the semiconductor storage device 1 according to the first embodiment is denoted by, for example, the same number or reference sign, description of the constituent component is omitted, and any configuration different from in the semiconductor storage device 1 will be described.
The gates of the selection transistors ST1 of the string units SU0 to SU3 are connected to the selection gate lines SGD0 to SGD3, respectively. Voltages of the selection gate lines SGD0 to SGD3 can be each independently controlled by the sequencer 170.
The gates of the selection transistors ST2 of the string units SU0 to SU3 are connected in common to a selection gate line SGS.
The sources of the selection transistors ST2 of the string units SU0 to SU3 are connected to the source lines SL0 to SL3, respectively. Voltages of the source lines SL0 to SL3 can be each independently controlled by the sequencer 170.
In the present embodiment, the source layer BSL is divided between two adjacent string units SU by a slit STD.
Thus, according to the present embodiment as well, it is possible to float (in other words, boost) any non-selected string unit SU and perform data writing and reading at high speed.
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 devices and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the devices and systems 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 modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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2022-044447 | Mar 2022 | JP | national |