阅读说明：本技术 半导体装置及制造方法 (Semiconductor device and method of manufacturing the same ) 是由 朱宏斌 陆振宇 戈登·哈勒 孙洁 兰迪·J·科瓦尔 约翰·霍普金斯 于 2017-10-17 设计创作，主要内容包括：一些实施例包含一种半导体装置,其具有堆叠结构,所述堆叠结构包含包括多晶硅的源极、在所述源极上的氧化物的蚀刻停止层、在所述蚀刻停止层上的选择栅极源极、在所述选择栅极源极上方的电荷存储结构,及在所述电荷存储结构上方的选择栅极漏极。所述半导体装置可进一步包含竖直地延伸到所述堆叠结构中到邻近所述源极的阶层的开口。包括多晶硅的沟道可形成在所述开口的侧表面及底表面上。所述沟道可在所述开口的下部分处接触所述源极,且所述沟道与所述电荷存储结构可被穿隧氧化物横向地分离。邻近所述选择栅极源极的所述沟道的宽度大于邻近所述选择栅极漏极的所述沟道的宽度。(Some embodiments include a semiconductor device having a stacked structure including a source comprising polysilicon, an etch stop layer comprising an oxide on the source, a select gate source on the etch stop layer, a charge storage structure over the select gate source, and a select gate drain over the charge storage structure. The semiconductor device may further include an opening extending vertically into the stacked structure to a level adjacent the source. A channel comprising polysilicon may be formed on side and bottom surfaces of the opening. The channel may contact the source at a lower portion of the opening, and the channel and the charge storage structure may be laterally separated by a tunnel oxide. The width of the channel adjacent the select gate source is greater than the width of the channel adjacent the select gate drain.)

1. A semiconductor device, comprising:

a stacked structure including, in combination,

a source electrode, a drain electrode and a source electrode,

a select gate source level above the source,

a charge storage structure above the select gate source level,

a select gate drain level above the charge storage structure, an

An opening defined in the stacked structure, the opening extending vertically into the stacked structure to a level adjacent the source; and

a channel comprising polysilicon formed over side and bottom surfaces defining the opening, the channel contacting the source at a lower portion of the opening, and the channel and the charge storage structure being laterally separated by a tunneling dielectric;

wherein a first width of the opening adjacent the charge storage structure is substantially the same as a second width of the opening adjacent the select gate drain level.

2. The semiconductor device of claim 1, wherein the charge storage structure is one of a plurality of charge storage structures in the stack structure, and wherein the second width of the opening adjacent the select gate drain level is substantially the same as a width of the opening adjacent the plurality of charge storage structures.

3. The semiconductor device of claim 1, wherein the source comprises polysilicon.

4. The semiconductor device of claim 1, further comprising a conductive polysilicon plug at an upper portion of the channel.

5. The semiconductor device of claim 4, wherein the conductive plug extends from an upper surface of the channel to a level adjacent the select gate drain level.

6. The semiconductor device of claim 4, wherein the conductive plug extends from an upper surface of the channel to a level adjacent the charge storage structure.

7. The semiconductor device of claim 1, wherein the charge storage structure comprises a floating gate.

8. A semiconductor device, comprising:

a stacked structure, the stacked structure comprising,

a source electrode, a drain electrode and a source electrode,

an etch stop layer over the source, comprising,

a first etch stop level comprising nitride over the source, and

a second etch stop level comprising an oxide above the first etch stop level,

a select gate source level above the etch stop layer,

a charge storage structure above the select gate source level,

a select gate drain level above the charge storage structure, an

An opening extending vertically into the stacked structure to a level adjacent the source; and

a channel comprising polysilicon formed on side and bottom surfaces of the opening, the channel contacting the source at a lower portion of the opening, and the channel and the charge storage structure being laterally separated by a tunneling dielectric, wherein a first width of the channel adjacent the select gate source level and the etch stop layer is greater than a second width of the channel adjacent the select gate drain level.

9. The semiconductor device of claim 8, wherein the stack structure further comprises a cap comprising a nitride formed above the select gate drain level.

10. The semiconductor device of claim 8, wherein the stack structure further comprises a control gate, the control gate and the charge storage structure being horizontally separated by an inter-polysilicon dielectric.

11. The semiconductor device of claim 10, wherein the inter-poly dielectric comprises a first oxide, a second oxide, and a nitride between the first oxide and the second oxide.

12. The semiconductor device of claim 10, wherein the source comprises tungsten silicide, the select gate source level comprises polysilicon, the control gate comprises polysilicon, and the select gate drain level comprises polysilicon.

13. A method of forming a semiconductor device, comprising:

forming a stacked structure, the stacked structure comprising,

a source electrode, a drain electrode and a source electrode,

a select gate source level above the source,

a plurality of control gate levels above the select gate source level, and

a select gate drain level above the control gate level;

forming an opening extending vertically into the stack structure, the opening extending through the select gate drain level, the select gate source level, and the plurality of control gate levels;

laterally etching a surface defining the opening to form a recess into the control gate level;

forming an inter-polysilicon dielectric over a bottom surface and side surfaces of the opening;

forming a charge storage structure in the recess; and

a channel comprising polysilicon is formed on the bottom and side surfaces of the opening, wherein a first width of the opening adjacent the charge storage structure is substantially the same as a second width of the opening adjacent the select gate drain level.

14. The method of claim 13, further comprising a dielectric etch stop layer over the source, wherein the source comprises polysilicon.

15. The method of claim 13, wherein forming the channel comprises:

removing the inter-poly dielectric from a surface defining sides of the opening while leaving the inter-poly dielectric over at least a portion of the source under the opening;

forming a liner comprising polysilicon on the bottom surface and the side surfaces of the opening;

removing the liner and the bottom surface of the inter-polysilicon dielectric to expose the source;

depositing polysilicon over the source sufficient to contact the liner at least on the side surfaces of the opening to form a continuous liner within the opening; and

a filler comprising an oxide is formed within the continuous liner.

16. The method of claim 13, further comprising:

removing the filler from an upper portion of the opening to a level adjacent the select gate drain; and

a plug comprising polysilicon is formed in the upper portion of the channel.

17. The method of claim 13, further comprising:

removing the filler from an upper portion of the opening to a level adjacent the charge storage structure; and

a plug comprising polysilicon is formed in the upper portion of the channel.

18. A method of forming a semiconductor device, comprising:

forming a stacked structure, the stacked structure comprising,

a source electrode, a drain electrode and a source electrode,

a first etch stop level comprising nitride over the source,

a second etch stop level comprising an oxide above the first etch stop level,

a select gate source level above the second etch stop level,

a control gate level above the select gate source level, an

A select gate drain level above the control gate level;

forming an opening to extend vertically into the stacked structure to expose the first etch stop level;

laterally etching the opening to form a recess into the control gate level;

forming an inter-polysilicon dielectric on a bottom surface and side surfaces of the opening;

forming a charge storage structure in the recess; and

forming a channel on the bottom surface and the side surfaces of the opening, wherein a first width of the opening adjacent the charge storage structure is substantially the same as a second width of the opening adjacent the select gate drain level.

19. The method of claim 18, wherein forming the channel comprises:

removing the inter-poly dielectric from portions of the side surfaces of the opening and removing the inter-poly dielectric and the first etch stop level from the bottom surface of the opening to expose the source;

forming a channel on the bottom surface and the side surfaces of the opening, wherein the channel and the charge storage structure are separated by a tunneling dielectric; and

a filler including a dielectric is formed within the liner.

20. The method of claim 18, further comprising: a plug comprising polysilicon is formed in an upper portion of the opening to extend vertically from a top surface of the opening to a level adjacent the select gate drain level.

21. The method of claim 18, further comprising forming a plug comprising polysilicon in an upper portion of the opening to extend vertically from a top surface of the opening to a level adjacent the charge storage structure.

22. The method of claim 18, wherein forming the charge storage structure comprises:

filling the opening with a polysilicon material;

removing the polysilicon material from portions of the openings while leaving the polysilicon material in the recesses to form the charge storage structures; and

a gate oxide is formed on a surface of the charge storage structure adjacent to the opening.

23. A method of forming a semiconductor device, comprising:

forming a stacked structure, the stacked structure comprising: a first select gate comprising polysilicon, a control gate comprising polysilicon over the first select gate, and a second select gate comprising polysilicon over the control gate, wherein the first select gate, the control gate, and the second select gate are of different doping configurations;

forming an opening through the stacked structure to extend vertically into the stack;

exposing the first select gate, the control gate, and the second select gate to an etching solution through the opening to form a recess in at least the polysilicon of the control gate; and

forming a charge storage structure in the recess formed in the polysilicon of the control gate.

24. The method of claim 23, wherein the etching solution used to form the recess comprises tetramethylammonium hydroxide (TMAH).

25. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate^-3Doping the first select gate with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

at about 1E21cm^-3Doping the second select gate with boron.

26. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate^-3Doping the first select gate level with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

at about 2E20cm^-3Doping the second select gate with boron.

27. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate^-3Doping the first select gate with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

at about 1E16cm^-3The second select gate is doped with carbon.

28. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate^-3Doping the first select gate with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

with about 1% to about 10% N₂Doping the second select gate.

29. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate source^-3Doping the first select gate with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

in a diffusion furnace at about 2E20cm^-3Doping the second select gate with boron.

30. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate^-3Doping the first select gate with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

by NH₃Doping the second select gate.

31. The method of claim 23, wherein forming the stacked structure comprises:

about 1 × 2E20cm during deposition of the first select gate^-3Doping the first select gate with boron;

about 1E21cm during PECVD of the control gate^-3Doping the control gate with phosphorus; and

ion beam implantation to about 2E20cm^-3The second select gate is doped with germanium.

32. The method of claim 23, wherein the polysilicon of the second select gate remains unrecessed after exposure to the etch solution.

Background

With the development of the semiconductor industry, three-dimensional (3D) semiconductor devices have been widely explored. However, the structure of 3D semiconductor devices including stacked levels (e.g., layers) and vertical channels extending into the stacked levels, as well as the techniques of fabricating such 3D semiconductor devices, may present some implementation challenges.

Drawings

Fig. 1A-1N are cross-sectional views depicting an example method of fabricating a 3D semiconductor device according to an embodiment of the present application, wherein each figure depicts a representative stage in forming the device.

Fig. 2A-2H are cross-sectional views depicting an example method of fabricating a 3D semiconductor device, according to another embodiment of the present application, wherein each figure depicts a representative stage in forming the device.

Fig. 3 is a flowchart showing a method of manufacturing a 3D semiconductor device according to an embodiment of the present application.

Fig. 4A-4H are cross-sectional views depicting an example method of fabricating a 3D semiconductor device, according to another embodiment of the present application, wherein each figure depicts a representative stage in forming the device.

Detailed Description

In the following detailed description of the embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific illustrative embodiments in which some embodiments of the invention may be practiced.

Recently, 3D semiconductor devices (e.g., 3D NAND memory devices) have come into use due to serious scaling challenges. However, 3D semiconductor devices including stacked levels and channels extending into the stacked levels impose structural and manufacturing challenges. For example, in a 3D semiconductor device, an interface may be present inside a channel extending into a stacked level.

The term "horizontal" as used in this document is defined as a plane parallel to the conventional plane or surface of a substrate, such as a substrate underlying a wafer or die, regardless of the actual orientation of the substrate at any point in time. The term "vertical" refers to a direction perpendicular to horizontal as defined above. Prepositions such as "upper", "above" and "below" are defined with respect to a conventional plane or surface on the top or exposed surface of a substrate, regardless of the orientation of the substrate; "on" is intended to indicate direct contact (in the absence of an explicit indication to the contrary) of one structure with respect to another structure on "; the terms "above" and "below" are expressly intended to identify relative placement of structures (or layers, features, etc.), which expressly include, but are not limited to, direct contact between identified structures unless expressly identified as such. Similarly, the terms "above" and "below" are not limited to a horizontal orientation, as a structure may be "above" a reference structure if the structure is the outermost portion of the construction at issue at some point in time, even though such structure extends vertically relative to the reference structure, rather than in a horizontal orientation.

The terms "wafer" and "substrate" are used herein to generally refer to any structure on which integrated circuits are formed, and also to such structures during various stages of integrated circuit fabrication. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled.

The NAND array architecture can store an array of memories (e.g., memory cells) configured such that the memories of the array are coupled in logical rows to access lines, commonly referred to as word lines. Some of the memories of the array are coupled together in series between a source line and a data line (commonly referred to as a bit line).

In some embodiments described herein, an etch stop layer of oxide (e.g., aluminum oxide) may be applied over a polycrystalline silicon source in a 3D semiconductor device.

In other embodiments described herein, an etch stop structure comprising a first etch stop layer of nitride and a second etch stop layer of oxide (e.g., aluminum oxide) may be applied over a tungsten silicide (hereinafter "WSiX") source in a 3D semiconductor device.

Thus, a monolithic channel may be realized in a 3D semiconductor device, wherein interfaces, vias and backfill inside the channel are reduced, such that a relatively independent gate control may be obtained.

In some embodiments described herein, different doping configurations may be applied to the Select Gate Source (SGS), the Control Gate (CG), and the Select Gate Drain (SGD), in this example, each of the SGS, CG, and SGD may be formed of or at least include polysilicon; as a result, these levels (e.g., comprising polysilicon) may have different etch rates when exposed to an etch solution. For example, in forming a monolithic pillar in a 3D semiconductor device, the SGS and CG may form a recess, while the SGD may remain less or even not recessed. Thus, these doping configurations may be capable of selectively etching into different levels (e.g., SGS, CG, and SGD) in a 3D semiconductor device by using an etching solution, such as tetramethylammonium hydroxide (TMCH).

Fig. 1A-1N are cross-sectional views depicting an example method of fabricating a 3D semiconductor device according to an embodiment of the present application, wherein each figure depicts a representative stage in forming the device.

Referring first to fig. 1A, a stacked structure 100 is formed. In some embodiments, the stack structure 100 may include a polysilicon source 101, an etch stop layer 102 of oxide on the source 101, a polysilicon SGS103 on the etch stop layer 102, a first isolation oxide 104 on the SGS103, a CG 105 (e.g., comprising polysilicon) on the first isolation oxide 104, a second isolation oxide 106 on the CG 105, and a poly SGD 107 on the second isolation oxide 106.

In some embodiments, the stack 100 may further include a nitride cap 108 on the SGD 107. In some embodiments, the stack 100 may further include a hard mask 109 (e.g., of carbon) on the nitride cap 108.

Referring to fig. 1B, an opening 110 is formed by etching to extend vertically into the stack 100 to expose the source 101.

Referring to fig. 1C, the opening 110 is laterally etched by using an etching solution (e.g., TMCH). Thus, a first lateral recess 112 is formed into the SGS103, and a second lateral recess 114 is formed into the CG 105. In some embodiments, the first recess 112 is formed into both the SGS103 and the etch stop layer 102. As will be explained in more detail with reference to fig. 3, the doping configuration of the SGS103, CG 105 and SGD 107 is different, and thus may result in selective etching into different levels (e.g., SGS103, CG 105 and SGD 107) at different lateral recess depths relative to the dimensions of the original opening 110. In some embodiments, a first lateral depth to a first recess 112 in the SGS103 is less than a second lateral depth to a second recess 114 in the CG 105, while the SGD 107 remains minimally concave, or even remains non-concave. It is apparent that once the lateral etching is performed, the lateral depth of these recesses changes the width of the opening at the etched level. Thus, the width of the opening 110 adjacent to the SGS103 is greater than the width of the opening 110 adjacent to the SGD 107.

Referring to fig. 1D, a dielectric 116 is deposited on the bottom and side surfaces of the opening 110 (and on the surfaces of the first and second recesses 112, 114), and the dielectric 116 may be considered an inter-polysilicon dielectric (IPD) structure 116. The IPD 116 may be formed as an "ONO" structure, including a first oxide 116A, a nitride 116B, and a second oxide 116C, with the nitride 116B between the first oxide 116A and the second oxide 116C.

Referring to fig. 1E, a charge storage structure is formed in the second recess 114. In the depicted example, the charge storage structure includes a Floating Gate (FG)120 that includes polysilicon formed in the second recess 114. In some embodiments not shown in the figures, the opening 110 (and the first and second recesses 112, 114) are first filled with polysilicon. The polysilicon is then removed from the opening 110 and the first recess 112, while the polysilicon remains in the second recess 114. The remaining portion of CG 105 may serve as a control gate. Accordingly, FG 120 is formed within second recess 114, and FG 120 is horizontally separated from CG 105 by IPO 116.

Referring to fig. 1F, a gate oxide 122 is formed on the side surface of FG 120 facing opening 110 to act as a tunneling oxide.

In some embodiments, portions of the IPD 116 are removed from the side and bottom surfaces of the opening 110. In some embodiments, a majority of IPD 116 (e.g., nitride 116B and second oxide 116C) is removed from the sides of opening 110, while a small portion of IPD 116 (e.g., second oxide 116C) is removed from the bottom surface of opening 110. Accordingly, the first oxide 116A of the IPD 116 may remain on the side surface of the opening 110, and the first oxide 116A and the nitride 116B of the IPD 116 may remain on the bottom surface of the opening 110.

Referring to fig. 1G, a polysilicon liner 130A is formed on the bottom and side surfaces of the opening 110. In some embodiments, a polysilicon liner 130A may be deposited on the bottom and side surfaces of the opening 110.

Referring to fig. 1H, the polysilicon on the bottom surface of the opening 110 and the liner 130A of the IPD 116 are removed (e.g., punched out) by etching down to expose the source 101, while the polysilicon liner 103A on the side surfaces of the opening 110 remains. The IPD 116 on the bottom surface of the opening 110 may serve as a protection (e.g., etch stop layer) to the source 101 during the etch-down process.

Referring to fig. 1I, a polysilicon deposit 130B is formed on the top surface of the source 101 by a downward deposition. Thus, the polysilicon deposit 130B contacts the polysilicon liner 130A deposited on the side surfaces of the opening 110. An integrated channel 130 (including both liner 103A and deposit 130B) is thus formed to work with source 101, SGS103, FG 120, and SGD 107.

In some embodiments, channel 130 contacts source 101 at a lower portion of opening 110, and channel 130 is laterally separated from SGS103, FG 120, and SGD 107 by an oxide.

Referring to fig. 1J, in some embodiments, the opening 110 is filled with an oxide fill 140.

Referring to fig. 1K, in some embodiments, the oxide fill 140 is removed from an upper portion of the opening 110 to form a shallow recess 110A, the shallow recess 110A extending from a top of the opening 110 to a level adjacent the SGD 107. Referring to fig. 1L, a polysilicon fill 150 may be filled into the shallow recess 110A (formed in an upper portion of the opening 110) to form a polysilicon plug 150.

Referring to fig. 1M, in other embodiments, the oxide fill 140 is removed from an upper portion of the opening 110 to form a deep recess 110B, the deep recess 110B extending from a top of the opening 110 to a level adjacent the FG 120. Referring to fig. 1N, a polysilicon fill 150 may be filled into the deep recess 110B (formed in an upper portion of the opening 110) to form a polysilicon plug 150.

Thus, as depicted above, the semiconductor device 100 may have an integrated channel 130 with no interface inside the channel. This process of manufacturing such semiconductor devices may provide relatively independent control of the gates.

Fig. 2A-2H are cross-sectional views depicting an example method of fabricating a 3D semiconductor device, according to another embodiment of the present application, wherein each figure depicts a representative stage in forming the device.

Referring first to fig. 2A, a stacked structure 200 is formed. In some embodiments, the stack structure 200 may include a WSiX source 201, a first etch stop layer 202A of nitride on the source 201, a second etch stop layer 202B of oxide on the first etch stop layer 202A, a polysilicon SGS 203 on the second etch stop layer 202B, a first isolation oxide 204 on the SGS 203, a polysilicon CG 205 on the first isolation oxide 204, a second isolation oxide 206 on the CG 205, and a polysilicon SGD207 on the second isolation oxide 206.

In some embodiments, the stack 200 may further include a nitride cap 208 on the SGD 207. In some embodiments, the stack 100 may further include a hard mask 209 (e.g., of carbon) on the nitride cap 208.

Referring to fig. 2B, an opening 210 is formed by etching to extend vertically into the stack 200 to a level adjacent the first etch stop layer 202A to expose the first etch stop layer 202A.

Referring to fig. 2C, the opening 210 is laterally etched by using an etching solution (e.g., TMCH) such that a first recess 212 is formed into the SGS 203 and a second recess 214 is formed into the CG 205. In some embodiments, a first lateral depth to a first recess 212 in the SGS 203 is less than a second lateral depth to a second recess 214 in the CG 205, while the SGD207 remains minimally concave, or even non-concave. Thus, the width of the opening 210 adjacent to the SGS 203 is greater than the width of the opening 210 adjacent to the SGD 207.

Referring to fig. 2D, an inter-polysilicon dielectric (IPD)216 is deposited on the bottom and side surfaces of the opening 210 (and on the surfaces of the first and second recesses 212, 214). The IPD 216 may include a first oxide 216A, a nitride 216B, and a second oxide 216C. Nitride 216B is between first oxide 216A and second oxide 216C.

Referring to fig. 2E, polysilicon FGs 220 are formed in the second recesses 214. In some embodiments not shown in the figures, the opening 210 (and the first and second recesses 212, 214) are first filled with a polysilicon material. Next, the polysilicon material is removed from the opening 210 and the first recess 212 by etching, while the polysilicon material remains in the second recess 214. The first etch stop layer 202A may function as an etch stop layer to protect the WSiX source 201 during the etching process. The remaining portion of the CG 205 may be used as a control gate. Accordingly, FG 220 is formed within the second recess 214, and FG 220 and CG 205 are horizontally separated by an IPO 216.

Referring to fig. 2F, a gate oxide 222 is formed on the side surface of FG 220 facing opening 210. The gate oxide 222 may be used as a tunneling oxide.

Referring to fig. 2G, a polysilicon liner 230 is deposited on the bottom and side surfaces of the opening 210 to serve as an integration channel.

Referring to fig. 2H, in some embodiments, the openings 210 are filled with an oxide fill 240.

Similar to the embodiment of the semiconductor device 100 as shown in fig. 1L and 1N, a polysilicon plug may be formed in an upper portion of the opening 210. In some embodiments, the polysilicon plug may extend from a top surface of the opening 210 to a shallow level adjacent the SGD 207. In other embodiments, the polysilicon plugs may extend from the top surface of the opening 210 to a deep level adjacent to the FG 220.

Thus, as depicted above, the semiconductor device 200 may have an integrated channel 230 with no interface inside the channel.

Fig. 3 is a flowchart showing a method of manufacturing a 3D semiconductor device according to an embodiment of the present application.

In some embodiments, during the process of fabricating semiconductor devices, different material configurations (e.g., doping differences) and the like may be employed within the stack of polysilicon SGS, CG and SGD to obtain different etch rates for the levels by using an etching solution (e.g., TMAH). Thus, a single column may be created in the semiconductor device, with the polysilicon SGS and CG forming recesses, respectively, while the polysilicon SGD is prevented from being etched, and thus is rarely, or even not, recessed.

Referring to fig. 3, at 302, a stack (e.g., 100) including polysilicon SGS (e.g., 103), CG (e.g., 105), and SGD (e.g., 107) is doped, wherein the SGS is doped with a first doping configuration, the CG is doped with a second doping configuration, and the SGD is doped with a third doping configuration.

At 304, an opening (e.g., 110) is formed by etching to extend vertically into the stack.

At 306, openings are laterally etched to form a first recess (e.g., 112) into the SGS, a second recess (e.g., 114) into the CG, and a third recess (not shown) into the SGD. In some embodiments, TMAH may be used to laterally etch openings to form recesses into SGS, CG and SGD.

Thus, after the lateral etching process, a first depth of a first recess etched into the SGS relative to the original size of the opening (110) is less than a second depth of a second recess etched into the CG, and a third depth of a third recess etched into the SGD is much less than the first depth of the first recess etched into the SGS. In some embodiments, the SGD may remain un-recessed after the lateral etching process.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3With boron doping a polysilicon SGS (e.g., 103) at about 1E21cm during Plasma Enhanced Chemical Vapor Deposition (PECVD) of CG^-3Doped with phosphorus and in a diffusion furnace at about 1E21cm^-3Is used to dope polysilicon SGD (e.g., 107) with boron.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during PECVD of CG^-3Doped with phosphorus and in a diffusion furnace at about 2E20cm^-3The polysilicon SGD is doped with boron.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during PECVD of CG^-3Doped with phosphorus and at a doping concentration of about 1E16cm^-3The polysilicon SGD is doped with carbon.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during Plasma Enhanced Chemical Vapor Deposition (PECVD) of CG^-3Doping concentration of (2) doping polysilicon CG with phosphorus and P at SGDECVD time period of about 2E20cm^-3The polysilicon SGD is doped with boron.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during PECVD of CG^-3Doped with phosphorus and about 1% to about 10% N₂And doping the polysilicon SGD.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during PECVD of CG^-3Doped with phosphorus and in a diffusion furnace at about 2E20cm^-3The polysilicon SGD is doped with boron.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during PECVD of CG^-3Doping concentration of (3) doping polysilicon CG with phosphorus and doping polysilicon with NH₃And doping the polysilicon SGD.

In some embodiments, at 302, about 1 × 2E20cm is applied during deposition of the SGS^-3Doping concentration of (a) doping polysilicon SGS with boron at about 1E21cm during Plasma Enhanced Chemical Vapor Deposition (PECVD) of CG^-3Doped with phosphorus and implanted with about 2E20cm using ion beam^-3The polysilicon SGD is doped with germanium.

Fig. 4A-4H are cross-sectional views depicting an example method of fabricating a 3D semiconductor device, according to another embodiment of the present application, wherein each figure depicts a representative stage in forming the device.

Referring first to fig. 4A, a stacked structure 400 is formed. In some embodiments, the stack structure 400 may include a polysilicon source 401, an etch stop layer 402 of oxide on the source 401, a polysilicon SGS 403 on the etch stop layer 402, a level stack 406 including at least one FG 420, and a polysilicon level 407 on the level stack 406. In some embodiments, the opening 450 may extend vertically into the stack 400 to expose the source 401. In some embodiments, the opening 450 may include a polysilicon liner 430. In some embodiments, the opening 450 may be filled with polysilicon.

Referring to fig. 4B, in some embodiments, the stack 400 may further include a nitride cap 408 on the polysilicon level 407.

Referring to fig. 4C, in some embodiments, spacers 408A may be formed by etching the nitride cap 408 down to expose the polysilicon levels 407.

Referring to fig. 4D, in some embodiments, a protective layer 460 may be formed over the surfaces of the opening 450, the spacer 408A, and the polysilicon level 407. In some embodiments, the protective layer 460 may include a multilayer resist (MLR) material.

Referring to fig. 4E, in some embodiments, the top surfaces of the opening 450 and the spacer 408A may be planarized by the protection of the protective layer 460 of the MLR.

Referring to fig. 4F, in some embodiments, a mask 470 may be formed over the openings 450 and the planarized top surface of the spacers 408A.

Referring to fig. 4G, in some embodiments, with the mask 470 on the planarized top surface of the opening 450 and spacer 408A, the entire protection layer 460 and portions of the polysilicon level 407 of the MLR may be selectively etched by etching down.

Referring to fig. 4H, in some embodiments, an oxide fill 480 may be filled to cover the level stack 406, the spacer 408A, the polysilicon level 407, and the opening 450.

Although many embodiments are described herein, these embodiments are not intended to be exhaustive. Although specific embodiments have been illustrated and described herein, it should be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This application is intended to cover any adaptations or variations of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon studying the above description.

The abstract of the specification is provided to comply with 37c.f.r. § 1.72(b), which requires an abstract that allows the reader to quickly ascertain the nature of the technical invention. It is submitted with the understanding that it will not be used to interpret or limit the claims. In addition, in the foregoing detailed description, it can be seen that various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of the invention is not to be construed as limiting the claims. Thus the following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.