INTEGRATION OF 3D STACKED IC DEVICE WITH PERIPHERAL CIRCUITS
An integrated circuit device includes a substrate including a first region and a second region. A pit is formed in the first region. A stack of active layers alternating with insulating layers is deposited in the pit. The stack includes a particular insulating layer. The particular insulating layer has a first thickness, where a sum of the first thickness, thickness of active layers, and thicknesses of other insulating layers is essentially equal to a depth of the pit. The first thickness is different than the thicknesses of the other insulating layers by an amount within a range of process variations for the depth of the pit, for the thicknesses of the active layers, and for the thicknesses of other insulating layers. The device includes a planarized surface over the first and second regions, where an uppermost one of the active layers has a top surface below the planarized surface.
1. Field of the Invention
The present invention relates to stacked transistor structures, such as can be used in high density three-dimensional (3D) memory devices, and memory devices utilizing such structures.
2. Description of Related Art
High density three-dimensional (3D) memory devices include stacked multiple planes of memory cells, and peripheral circuits. The peripheral circuits can include circuitry for example that controls the memory cells for program, erase and read operations. Metal layers or other conductive or semiconductive layers can electrically connect the peripheral circuits to the memory cells. Typically, the peripheral circuits are manufactured in CMOS (complementary metal-oxide-semiconductor) technology, while the stacked multiple planes of memory cells are manufactured in different technologies such as charge trapping memory technologies that requires process steps that are different from those used to form the peripheral circuits.
It is desirable to provide a technology for a three-dimensional (3D) memory device to facilitate integration of stacked multiple planes of memory cells with peripheral circuits of the three-dimensional (3D) memory device.
SUMMARYA technology for integrating stacked multiple planes of memory cells with peripheral circuits in three-dimensional memory devices is provided. An integrated circuit device in accordance with the technology includes a substrate including a first region and a second region. A pit is formed in the first region. A stack of active layers alternating with insulating layers is deposited in the pit.
The stack includes a particular insulating layer. The particular insulating layer has a first thickness, where a sum of the first thickness, thickness of active layers, and thicknesses of other insulating layers in the stack is essentially equal to a depth of the pit. The first thickness is different than the thicknesses of the other insulating layers in the stack by an amount within a range of process variations for the depth of the pit, for the thicknesses of the active layers, and for the thicknesses of other insulating layers. The device includes a planarized surface over the first and second regions, where an uppermost one of the active layers has a top surface below the planarized surface.
A method in accordance with the technology includes etching a substrate to form a pit, where the pit has a target depth below a top surface of the substrate, and measuring a depth of the etched pit. The method includes depositing a stack of active layers alternating with insulating layers on the substrate at least in the etched pit, where the stack has at least one insulating layer having a thickness based on a difference between the target depth and the measured depth of the etched pit. The method includes applying a planarizing process to provide a planarized surface.
Other aspects and advantages of the present invention can be seen on review of the drawings, the detailed description and the claims, which follow.
A detailed description of embodiments of the present invention is provided with reference to the
In the example shown in
Bit line structures 112A, 113A, 114A, and 115A terminate semiconductor lines, such as semiconductor lines 112, 113, 114, and 115. As illustrated, these bit line structures 112A, 113A, 114A, and 115A are electrically connected to different bit lines for connection to decoding circuitry to select planes within the array. These bit line structures 112A, 113A, 114A, and 115A can be patterned at the same time that the plurality of stacks is defined.
Bit line structures 102B, 103B, 104B, and 105B terminate semiconductor lines, such as semiconductor lines 102, 103, 104, and 105. As illustrated, these bit line structures 102B, 103B, 104B, and 105B are electrically connected to different bit lines for connection to decoding circuitry to select planes within the array. These bit line structures 102B, 103B, 104B, and 105B can be patterned at the same time that the plurality of stacks is defined.
Any given stack of semiconductor lines is coupled to either the bit line structures 112A, 113A, 114A, and 115A, or the bit line structures 102B, 103B, 104B, and 105B, but not both. A stack of semiconductor bit lines has one of the two opposite orientations of bit line end-to-source line end orientation, or source line end-to-bit line end orientation. For example, the stack of semiconductor lines 112, 113, 114, and 115 has bit line end-to-source line end orientation; and the stack of semiconductor lines 102, 103, 104, and 105 has source line end-to-bit line end orientation.
The stack of semiconductor lines 112, 113, 114, and 115 is terminated at one end by the bit line structures 112A, 113A, 114A, and 115A, passes through SSL gate structure 119, ground select line GSL 126, word lines 125-1 WL through 125-N WL, ground select line GSL 127, and is terminated at the other end by source line 128. The stack of semiconductor lines 112, 113, 114, and 115 does not reach the bit line structures 102B, 103B, 104B, and 105B.
The stack of semiconductor lines 102, 103, 104, and 105 is terminated at one end by the bit line structures 102B, 103B, 104B, and 105B, passes through SSL gate structure 109, ground select line GSL 127, word lines 125-N WL through 125-1 WL, ground select line GSL 126, and is terminated at the other end by a source line (obscured by other parts of the figure). The stack of semiconductor lines 102, 103, 104, and 105 does not reach the bit line structures 112A, 113A, 114A, and 115A.
A layer of memory material is disposed in interface regions at cross-points between surfaces of the semiconductor lines 112-115 and 102-105 and the plurality of word lines 125-1 through 125-n. Ground select lines GSL 126 and GSL 127 are conformal with the plurality of stacks, similar to the word lines.
Every stack of semiconductor lines is terminated at one end by bit line structures and at the other end by a source line. For example, the stack of semiconductor lines 112, 113, 114, and 115 is terminated at one end by bit line structures 112A, 113A, 114A, and 115A, and terminated on the other end by a source line 128. At the near end of the figure, every other stack of semiconductor lines is terminated by the bit line structures 102B, 103B, 104B, and 105B, and every other stack of semiconductor lines is terminated by a separate source line. At the far end of the figure, every other stack of semiconductor lines is terminated by the bit line structures 112A, 113A, 114A, and 115A, and every other stack of semiconductor lines is terminated by a separate source line.
Bit lines and string select lines are formed at the metals layers ML1, ML2, and ML3. Bit lines are coupled to a plane decoder (not shown). String select lines are coupled to a string select line decoder (not shown).
The ground select lines GSL 126 and 127 can be patterned during the same step that the word lines 125-1 through 125-n are defined. Ground select devices are formed at cross-points between surfaces of the plurality of stacks and ground select lines GSL 126 and 127. The SSL gate structures 119 and 109 can be patterned during the same step that the word lines 125-1 through 125-n are defined. String select devices are formed at cross-points between surfaces of the plurality of stacks and string select (SSL) gate structures 119 and 109. These devices are coupled to decoding circuitry for selecting the strings within particular stacks in the array.
In the example shown in
The memory device includes memory elements in interface regions at cross-points 280 between side surfaces of the conductive strips in the plurality of intermediate planes (WLs) in the stacks and the inter-stack semiconductor body elements 220 of the plurality of bit line structures.
A reference conductor 260 is disposed between the bottom plane (GSL) of conductive strips and the integrated circuit substrate 201. At least one reference line structure is arranged orthogonally over the plurality of stacks, including inter-stack semiconductor elements 240 between the stacks in electrical communication with the reference conductor 260, and linking elements 250 over the stacks 210 connecting the inter-stack semiconductor elements 240. The semiconductor elements 240 have a higher conductivity than the semiconductor body elements 220.
The memory device includes string select switches 290 at interface regions with the top plane of conductive strips, and reference select switches 270 at interface regions with the bottom plane (GSL) of conductive strips.
In the example shown in
Conductive strips in the intermediate planes (WLs), and conductive strips in the bottom plane (GSL) are connected together to reduce decoder areas and consequently an overall size of the memory device. Conductive strips in the top plane (SSL) are individually decoded to allow correct bit line decoding.
The memory device can include linking elements, such as linking elements 261 and 262, connecting sets of word lines in the intermediate planes (WL), and interlayer connectors, such as interlayer connectors 271 and 272, coupled to landing areas in the linking elements 261 and 262, and to the word line decoding circuits (not shown). The landing areas are at interface regions between bottom surfaces of the interlayer connectors and top surfaces of the linking elements.
In the example shown in
The memory device can include ground selection line decoding circuits coupled to the at least one bottom plane (GSL) of conductive strips in the plurality of stacks. The memory device can include linking elements, such as a linking element 263, connecting sets of ground selection lines in the bottom plane (GSL) of conductive strips, and interlayer connectors, such as an interlayer connector 273, coupled to landing areas in the linking elements, and to the ground selection line decoding circuits (not shown). The landing areas are at interface regions between bottom surfaces of the interlayer connectors, such as an interlayer connector 273, and top surfaces of the linking elements, such as a linking element 263. The vertical contact region (e.g. 314 in
In the example shown in
Three-dimensional memory (3D) devices, such as the ones illustrated by
The structures of
Process variation in stacking active layers alternating with insulating layers in the memory cell region 312 and the vertical contact region 314 can be addressed as described herein, to facilitate integration of the memory cell region with the components of the peripheral circuits of the integrated circuit device in the peripheral region 318. Device 300 is illustrated as an example of one type of integrated circuit device with which the present invention can be used; others are also possible. In the example shown in
In the example shown in
The vertical contact region 314 can include bit line structures 102B, 103B, 104B, and 105B, and bit line structures 112A, 113A, 114A, and 115A, connected to bit lines at metals layers ML1, ML2, and ML3, as illustrated in
Components of peripheral circuits in the peripheral region 318 can include the decoding circuitry such as described for the memory devices illustrated in
A planarized surface is formed over the memory cell region 312, the vertical contact region 314, the isolation region 316, and the peripheral region 318. Patterned metal layers are formed over the planarized surface. In reference to the memory device illustrated in
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As described herein, the target depth can be calculated as greater than or equal to a sum of target thicknesses of a stack of active layers and insulating layers to be deposited in the pit, such that an uppermost one of the active layers in the stack has a top surface below the top surface 420 of the substrate 430 after deposition of the stack. However, the measured depth 540 of the pit 520 may be less than the target depth of the pit 520. To compensate for the difference between the target depth and the measured depth 540, the target thickness of the bottom insulating layer 610 can be adjusted by the difference, such that the uppermost one of the active layer has a top surface below the top surface 420 of the substrate 430 after deposition of the stack.
Insulating layers in the stack can be the same or different as the other layers. Representative insulating materials that can be used include an oxide, nitride, oxynitride, silicate, or others. Low insulating constant materials having an insulating constant smaller than that of silicon dioxide, such as SiCHOx, can be used. High insulating constant (high-k) materials having an insulating constant greater than that of silicon dioxide, such as HfOx, HfON, AlOx, RuOx, TiOx, can be used also.
Conductor or semiconductor layers in the stack can be the same or different as the other layers. Representative materials that can be used include electrically conductive semiconductors including heavily doped polysilicon (using dopants such as As, P, B), silicides including TiSi, CoSi, oxide semiconductors, including InZnO, InGaZnO, and combinations of semiconductors and silicides. Conductive layers in the stack can also be a metal, a conductive compound, or combinations of materials including Al, Cu, W, Ti, Co, Ni, TiN, TaN, TaAlN, and others.
Due to process variation, there may be a difference between the target thickness 615 and the measured thickness 815 of the bottom insulating layer 610. The process variation may be among chips on a wafer, or among chips on different wafers. The measured thickness 815 can be within a range of the target thickness 615. In some example processes, the measured thickness 815 can be within +/−5% of the target thickness 615. Said another way, in some example processes, if the target thickness 615 is 200 nanometers, the measured thickness 815 can be between 190 nanometers and 210 nanometers.
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As described herein, due to process variation, there may be a difference between the target thickness 615 and the measured thickness 815 of the bottom insulating layer 610 (
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Although
The thickness of the top insulating layer 1350 can be calculated as the difference between the measured depth 540 of the pit 520 and a sum of the measured thicknesses of active layers (e.g. 1320, 1340) and insulating layers (e.g. 1310, 1330) already deposited in the pit 520. The material of the top insulating layer 1350 can include the same material as for other insulating layers (e.g. 1310, 1330) such as oxide, nitride, oxynitride, silicate, or others.
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Components of the peripheral circuits that can be formed over the peripheral region 1518 1810 include decoding circuitry such as described for the memory devices illustrated in
The present invention provides an integrated circuit device including a substrate including a first region and a second region. A recessed area, or a pit, is formed in the first region, where the pit has a depth. The integrated circuit device includes a stack of active layers alternating with insulating layers deposited in the pit. The active layers can include semiconductor or conductive materials. The insulating layers can include dielectric materials.
The stack includes a particular insulating layer in the insulating layers. The particular insulating layer has a first thickness, where a sum of the first thickness of the particular insulating layer, thickness of active layers, and thicknesses of other insulating layers in the stack is essentially equal to the depth of the pit. The first thickness is different than the thicknesses of the other insulating layers in the stack by an amount within a range of process variations for the depth of the pit, for the thicknesses of the active layers, and for the thicknesses of insulating layers in completed stack other than the particular insulating layer. The integrated circuit device includes a planarized surface over the first region and the second region, where an uppermost one of the active layers has a top surface below the planarized surface.
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While the present invention is disclosed by reference to the preferred embodiments and examples detailed above, it is to be understood that these examples are intended in an illustrative rather than in a limiting sense. It is contemplated that modifications and combinations will readily occur to those skilled in the art, which modifications and combinations will be within the spirit of the invention and the scope of the following claims. What is claimed is:
Claims
1. A method for manufacturing an integrated circuit device, comprising:
- etching a substrate to form a pit, the pit having a target depth below a top surface of the substrate;
- measuring a depth of the etched pit;
- depositing a stack of active layers alternating with insulating layers on the substrate at least in the etched pit, wherein the stack has at least one insulating layer having a thickness based on a difference between the target depth and the measured depth of the etched pit; and
- applying a planarizing process to provide a planarized surface, wherein an uppermost one of the active layers has a top surface below the planarized surface.
2. The method of claim 1, further comprising etching the stack in a pattern to define an isolation region in the pit separating the stack from a peripheral region.
3. The method of claim 2, wherein the applying a planarizing process comprises:
- forming a stopping layer over the stack, the isolation region, and the peripheral region;
- depositing an insulation fill over the stopping layer in the isolation region;
- polishing the insulation fill down to a level on or within the stopping layer; and
- removing portions of the stopping layer above a level at the top surface of the substrate.
4. The method of claim 2, further comprising forming components of peripheral circuits over the peripheral region.
5. The method of claim 1, wherein the at least one insulating layer includes a bottom insulating layer in the stack, the bottom insulating layer having a target thickness based on the difference.
6. The method of claim 1, wherein the at least one insulating layer includes a bottom insulating layer having a target thickness based on the difference, further comprising:
- measuring a thickness of the deposited bottom insulating layer; and
- depositing a second insulating layer over and in contact with the bottom insulating layer, wherein the second insulating layer has a second thickness based on the measured thickness of the deposited bottom insulating layer.
7. The method of claim 1, wherein the target depth of the pit is greater than the thickness of the stack, further comprising:
- measuring a thickness of the deposited stack; and
- depositing a top insulating layer over the stack, wherein the top insulating layer has a thickness based on the measured thickness of the deposited stack and the measured depth of the pit.
8. The method of claim 1, wherein the stack includes a lower sub-stack including some of the active layers alternating with insulating layers in the stack, and an upper sub-stack including others of the active layers alternating with insulating layers in the stack, and wherein the at least one insulating layer includes an intermediate insulating layer disposed in-between the lower sub-stack and the upper sub-stack, further comprising:
- measuring a lower sub-stack thickness of the active layers and alternating insulating layers in the lower sub-stack, after deposition of the lower sub-stack and before deposition of the upper sub-stack; and
- depositing the intermediate insulating layer over the lower sub-stack, wherein the intermediate insulating layer has a thickness based on the measured depth of the pit and the measured lower sub-stack thickness.
9. The method of claim 1, further comprising:
- forming interlayer connectors connected to respective active layers in the stack, the interlayer connectors extending from the respective active layers in the stack in the pit to a connector surface higher than the planarized surface; and
- forming patterned conductor lines on top of the connector surface and connected to the respective interlayer connectors.
10. The method of claim 1, further comprising:
- etching the stack to define a plurality of active strips including at least a plurality of planes of active strips;
- forming a memory layer over and in contact with side surfaces of active strips in the plurality of planes;
- forming a layer of a second conductive material over and having a surface conformal with the memory layer;
- etching the layer of the second conductive material to define a plurality of structures arranged orthogonally over, and having surfaces conformal with, the plurality of active strips in the plurality of planes; and
- etching the memory layer to define memory elements in interface regions at cross-points between side surfaces of active strips in the plurality of planes and the plurality of structures.
11. An integrated circuit device, comprising:
- a substrate including a first region and a second region;
- a pit formed in the first region, the pit having a depth;
- a stack of active layers alternating with insulating layers deposited in the pit, wherein the stack includes: a particular insulating layer having a first thickness, wherein a sum of the first thickness of the particular insulating layer, thicknesses of active layers, and thicknesses of other insulating layers in the stack is essentially equal to the depth, the first thickness being different than the thicknesses of the other insulating layers in the stack by an amount within a range of process variations for the depth of the pit, for the thicknesses of active layers, and for the thicknesses of other insulating layers; and
- a planarized surface over the first region and the second region, wherein an uppermost one of the active layers has a top surface below the planarized surface.
12. The integrated circuit device of claim 11, further comprising:
- an isolation region in the pit separating the stack from the second region including a peripheral region; and
- a stopping layer between the stack and the isolation region and between the isolation region and the peripheral region.
13. The integrated circuit device of claim 12, further comprising components of peripheral circuits over the peripheral region.
14. The integrated circuit device of claim 11, wherein the particular insulating layer includes a bottom insulating layer formed on a bottom of the pit.
15. The integrated circuit device of claim 11, wherein the particular insulating layer is formed on a bottom insulating layer formed on a bottom of the pit, wherein a sum of the first thickness of the particular insulating layer, a second thickness of the bottom insulating layer, thicknesses of active layers, and thicknesses of other insulating layers in the stack is essentially equal to the target depth.
16. The integrated circuit device of claim 11, wherein an uppermost one of the insulating layers is formed on the uppermost one of the active layers, and the particular insulating layer having the first thickness is formed on the uppermost one of the insulating layers.
17. The integrated circuit device of claim 11, wherein the particular insulating layer includes an intermediate insulating layer formed between two adjacent active layers.
18. The integrated circuit device of claim 11, further comprising:
- interlayer connectors connected to respective active layers in the stack, the interlayer connectors extending from the respective active layers in the stack in the pit to a connector surface higher than the planarized surface; and
- patterned conductor lines on top of the connector surface and connected to the respective interlayer connectors.
19. The integrated circuit device of claim 11, further comprising:
- a plurality of active strips including at least a plurality of planes of active strips;
- a plurality of structures arranged orthogonally over, and having surfaces conformal with, the plurality of active strips in the plurality of planes; and
- memory elements in interface regions at cross-points between side surfaces of active strips in the plurality of planes and the plurality of structures.
Type: Application
Filed: Jan 11, 2013
Publication Date: Jul 17, 2014
Inventors: Hang-Ting Lue (Hsinchu), Yi-Hsuan Hsiao (Budai Township), Shih-Hung Chen (Jhudong Township), Yen-Hao Shih (New Taipei City)
Application Number: 13/739,914
International Classification: H01L 21/66 (20060101); H01L 29/06 (20060101);