阅读说明：本技术 半导体结构及半导体结构的形成方法 (Semiconductor structure and method for forming semiconductor structure ) 是由 张海洋 王胜 于 2020-05-18 设计创作，主要内容包括：一种半导体结构及半导体结构的形成方法,结构包括：衬底；位于衬底上的隔离结构；分别位于隔离结构两侧的第一纳米线和第二纳米线；位于第一纳米线和隔离结构之间的第一阻挡层,位于第二纳米线和隔离结构之间的第二阻挡层。所述半导体结构的性能得到提升。(A semiconductor structure and a method for forming the same, the structure comprising: a substrate; an isolation structure located on the substrate; the first nanowire and the second nanowire are respectively positioned on two sides of the isolation structure; the first barrier layer is positioned between the first nanowire and the isolation structure, and the second barrier layer is positioned between the second nanowire and the isolation structure. The performance of the semiconductor structure is improved.)

1. A semiconductor structure, comprising:

a substrate;

an isolation structure located on the substrate;

the first nanowire and the second nanowire are respectively positioned on two sides of the isolation structure;

the first barrier layer is positioned between the first nanowire and the isolation structure, and the second barrier layer is positioned between the second nanowire and the isolation structure.

2. The semiconductor structure of claim 1, wherein the first nanowire is plural in number, and the plural first nanowires are separated from each other and constitute the first nanostructure; the number of the second nanowires is multiple, and the multiple second nanowires are mutually separated and form a second nano structure.

3. The semiconductor structure of claim 2, wherein the first nanostructure further comprises: a first underlying nanowire positioned between the substrate and the first nanowire; the second nanostructure further comprises: a second bottom layer of nanowires located between the substrate and the second nanowires; the first bottom layer nanowire and the second bottom layer nanowire are respectively positioned on two sides of the isolation structure.

4. The semiconductor structure of claim 3, wherein the isolation structure comprises a first isolation layer and a second isolation layer on the first isolation layer, the first isolation layer being between the first underlying nanowire and the second underlying nanowire, the second isolation layer being between the first nanowire and the second nanowire.

5. The semiconductor structure of claim 4, wherein the material of the first isolation layer comprises a dielectric material comprising silicon oxide; the material of the second isolation layer comprises a dielectric material comprising silicon oxide.

6. The semiconductor structure of claim 1, wherein the material of the first barrier layer comprises a dielectric material comprising silicon nitride or silicon oxycarbide; the material of the second barrier layer comprises a dielectric material comprising silicon nitride or silicon oxycarbide.

7. The semiconductor structure of claim 1, further comprising: a gate structure surrounding the first and second nanowires, and the gate structure straddles the isolation structure.

8. A method of forming a semiconductor structure, comprising:

providing a substrate;

forming an initial stacked structure on a substrate, wherein the initial stacked structure comprises a plurality of initial sacrificial layers and initial nanowires positioned between two adjacent initial sacrificial layers;

forming a dielectric layer on the substrate, wherein the dielectric layer is positioned on the side wall of the initial stacking structure;

removing part of the initial stacked structure until the surface of the substrate is exposed, forming a first opening in the initial stacked structure, and forming a first nanowire and a second nanowire on two sides of the first opening;

forming a first barrier layer on the side wall of the first nanowire exposed by the first opening;

forming a second barrier layer on the side wall of the second nanowire exposed by the first opening;

an isolation structure is formed within the first opening.

9. The method for forming a semiconductor structure according to claim 8, wherein the first nanowires are located between two adjacent first sacrificial layers, the number of the first nanowires is plural, and the plurality of first nanowires and the plurality of first sacrificial layers form an initial first nanostructure; the second nanowires are positioned between the second sacrificial layers of the two adjacent layers, the number of the second nanowires is multiple, and the multiple second nanowires and the multiple second sacrificial layers form an initial second nanostructure; the initial first nanostructures and the initial second nanostructures are located on both sides of the first opening.

10. The method of forming a semiconductor structure of claim 9, wherein the initial stacked structure further comprises an initial underlying nanowire located between the substrate and an initial sacrificial layer; the initial first nanostructure further comprises a first bottom layer of nanowires located between the substrate and the first sacrificial layer; the initial second nanostructure also includes a second underlying nanowire located between the substrate and the second sacrificial layer.

11. The method of forming a semiconductor structure of claim 10, wherein the method of forming the initial stack structure comprises: forming a stacked material structure on a substrate, wherein the stacked material structure comprises a bottom layer nanowire material layer, a plurality of sacrificial material layers positioned on the bottom layer nanowire material layer, and nanowire material layers positioned between adjacent sacrificial material layers; forming a hard mask layer on the stacked material structure, wherein the hard mask layer exposes part of the sacrificial material layer; and taking the hard mask layer as a mask, removing part of the stacked material structure until the surface of the substrate is exposed, forming a second opening in the stacked material structure, and forming the initial stacked structure.

12. The method of forming a semiconductor structure of claim 11, wherein the method of forming the first opening comprises: forming an initial filling layer in the second opening, wherein the filling layer is also positioned on the side wall of the hard mask layer; after the initial filling layer is formed, removing the hard mask layer, and forming a third opening in the dielectric layer, wherein the third opening exposes the top surface of the initial stacking structure and part of the side wall surface of the initial filling layer; forming a covering layer on the inner wall surface of the third opening, wherein the covering layer forms a fourth opening in the dielectric layer; and removing the covering layer and the initial stacking structure at the bottom of the fourth opening until the surface of the substrate is exposed, and forming a first opening in the dielectric layer.

13. The method of forming a semiconductor structure of claim 12, further comprising, after forming the isolation structure: removing part of the initial filling layer, and forming a filling layer in the second opening, wherein the filling layer is respectively positioned on the side wall surface of the first bottom layer nanowire and the side wall surface of the second bottom layer nanowire; after forming the filling layer, removing the covering layer; after the covering layer is removed, removing the first sacrificial layer and the second sacrificial layer to form a first nano structure and a second nano structure, forming first grid openings between adjacent first nanowires and between the first nanowires and the first bottom nanowires, and forming second grid openings between adjacent second nanowires and between the second nanowires and the second bottom nanowires; forming a gate structure in the first gate opening and in the second gate opening, the gate structure crossing the isolation structure.

14. The method of forming a semiconductor structure of claim 13, wherein after forming the isolation structure and before removing the initial fill layer, further comprising: forming an initial protective layer on the isolation structure and the capping layer; and etching back the covering layer and the initial protective layer until the surface of the initial filling layer is exposed, and forming protective layers on the isolation structure, the initial first nano structure and the initial second nano structure.

15. The method of forming a semiconductor structure of claim 14, wherein a material of the protective layer is different from a material of the initial fill layer.

16. The method of forming a semiconductor structure of claim 12, wherein a material of the capping layer is different from a material of the initial fill layer.

17. The method of forming a semiconductor structure of claim 12, wherein a material of the hard mask layer is different from a material of the initial fill layer.

18. The method of forming a semiconductor structure of claim 12, wherein the material of the initial fill layer comprises a dielectric material comprising silicon oxide.

19. The method of forming a semiconductor structure of claim 12, wherein the capping layer has a thickness in a range of 10nm to 100 nm.

20. The method of forming a semiconductor structure of claim 12, wherein the process of forming the capping layer comprises an atomic layer deposition process.

21. The method of forming a semiconductor structure of claim 10, wherein the isolation structure comprises a first isolation layer and a second isolation layer on the first isolation layer; the first isolation layer is positioned between the first bottom layer nanowire and the second bottom layer nanowire, and the second isolation layer is positioned between the first nanowire and the second nanowire.

22. The method of forming a semiconductor structure of claim 21, wherein the method of forming the first and second barrier layers comprises: forming a first isolation layer in the first opening, wherein the first isolation layer exposes the first nanowire side wall and the second nanowire side wall; removing part of the first nanowire and the second nanowire, forming a first groove on the side wall of the first nanowire, and forming a second groove on the side wall of the second nanowire; and forming a first barrier layer in the first groove and forming a second barrier layer in the second groove.

23. The method of forming a semiconductor structure of claim 21, wherein a material of the first isolation layer is different from a material of the capping layer; the material of the second isolation layer is different from the material of the cover layer.

24. The method of forming a semiconductor structure of claim 23, wherein the material of the first spacer layer comprises a dielectric material comprising silicon oxide; the material of the second isolation layer comprises a dielectric material, and the dielectric material comprises silicon oxide; the material of the cover layer comprises a dielectric material, and the dielectric material comprises silicon nitride.

25. The method of forming a semiconductor structure of claim 21, wherein the method of forming the second isolation layer comprises: forming an isolation material layer on the first isolation layer; and etching back the isolation material layer to form a second isolation layer.

26. The method of forming a semiconductor structure of claim 21, wherein the method of forming the first isolation layer comprises: forming an isolation material layer in the first opening; and etching back the isolation material layer to form a first isolation layer.

27. The method of forming a semiconductor structure of claim 8, wherein the material of the first barrier layer comprises a dielectric material, the dielectric material comprising silicon nitride or silicon oxycarbide; the material of the second barrier layer comprises a dielectric material, and the dielectric material comprises silicon nitride or silicon oxycarbide.

Technical Field

The present invention relates to the field of semiconductor manufacturing, and more particularly, to a semiconductor structure and a method for forming the same.

Background

Finfet transistor architectures are the dominant industry today. However, with the continuous scaling of devices, when the channel length is small to a certain value, the finfet structure cannot provide sufficient electrostatic control and sufficient driving current, so that a Nanosheet (nano-sheet) structure, namely, Gate-All-Around (GAA) technology is introduced, and compared with the finfet, the GAA characteristic of the Nanosheet provides excellent channel control capability. At the same time, the excellent distribution of the channels in three dimensions allows the effective drive current per unit area to be optimized.

As the journey to smaller rail heights continues, further reductions in cell height will require smaller spacing between NMOS and PMOS devices within the standard cell. However, for finfet and nanosheets, the process limits the spacing between these NMOS and PMOS devices. To expand the scalability of these devices, an innovative architecture is proposed, called the forkbolt nanosheet (forskhet) device. The forked nanoplates can be considered as natural extensions of the nanoplates. In contrast to the nanoplates, the channels of the forked nanoplates are controlled by a forked gate structure, which is achieved by introducing "dielectric walls" between the NMOS and PMOS devices prior to gate patterning. The NMOS gate groove and the PMOS gate groove are physically isolated by the wall, so that the distance between the NMOS and the PMOS is greatly reduced, and the forked nano-sheet has better area and property and can be miniaturized.

However, the properties of the forked nanoplatelets remain to be improved.

Disclosure of Invention

The invention provides a semiconductor structure and a forming method thereof, which aims to improve the performance of the semiconductor structure.

To solve the above technical problem, an embodiment of the present invention provides a semiconductor structure, including: a substrate; an isolation structure located on the substrate; the first nanowire and the second nanowire are respectively positioned on two sides of the isolation structure; the first barrier layer is positioned between the first nanowire and the isolation structure, and the second barrier layer is positioned between the second nanowire and the isolation structure.

Optionally, the number of the first nanowires is multiple, and the multiple first nanowires are separated from each other and form a first nanostructure; the number of the second nanowires is multiple, and the multiple second nanowires are mutually separated and form a second nano structure.

Optionally, the first nanostructure further comprises: a first underlying nanowire positioned between the substrate and the first nanowire; the second nanostructure further comprises: a second bottom layer of nanowires located between the substrate and the second nanowires; the first bottom layer nanowire and the second bottom layer nanowire are respectively positioned on two sides of the isolation structure.

Optionally, the isolation structure includes a first isolation layer and a second isolation layer located on the first isolation layer, the first isolation layer is located between the first bottom layer nanowire and the second bottom layer nanowire, and the second isolation layer is located between the first nanowire and the second nanowire.

Optionally, the material of the first isolation layer includes a dielectric material, and the dielectric material includes silicon oxide; the material of the second isolation layer comprises a dielectric material comprising silicon oxide.

Optionally, the material of the first barrier layer includes a dielectric material, and the dielectric material includes silicon nitride or silicon oxycarbide; the material of the second barrier layer comprises a dielectric material, and the dielectric material comprises silicon nitride or silicon oxycarbide.

Optionally, the method further includes: a gate structure surrounding the first and second nanowires, and the gate structure straddles the isolation structure.

Correspondingly, the technical scheme of the invention also provides a method for forming the semiconductor structure, which comprises the following steps: providing a substrate; forming an initial stacked structure on a substrate, wherein the initial stacked structure comprises a plurality of initial sacrificial layers and initial nanowires positioned between two adjacent initial sacrificial layers; forming a dielectric layer on the substrate, wherein the dielectric layer is positioned on the side wall of the initial stacking structure; removing part of the initial stacked structure until the surface of the substrate is exposed, forming a first opening in the initial stacked structure, and forming a first nanowire and a second nanowire on two sides of the first opening; forming a first barrier layer on the side wall of the first nanowire exposed by the first opening; forming a second barrier layer on the side wall of the second nanowire exposed by the first opening; an isolation structure is formed within the first opening.

Optionally, the first nanowires are located between two adjacent first sacrificial layers, the number of the first nanowires is multiple, and the multiple first nanowires and the multiple first sacrificial layers form an initial first nanostructure; the second nanowires are positioned between the second sacrificial layers of the two adjacent layers, the number of the second nanowires is multiple, and the multiple second nanowires and the multiple second sacrificial layers form an initial second nanostructure; the initial first nanostructures and the initial second nanostructures are located on both sides of the first opening.

Optionally, the initial stacked structure further comprises an initial bottom layer nanowire located between the substrate and the initial sacrificial layer; the initial first nanostructure further comprises a first bottom layer of nanowires located between the substrate and the first sacrificial layer; the initial second nanostructure also includes a second underlying nanowire located between the substrate and the second sacrificial layer.

Optionally, the method for forming the initial stacked structure includes: forming a stacked material structure on a substrate, wherein the stacked material structure comprises a bottom layer nanowire material layer, a plurality of sacrificial material layers positioned on the bottom layer nanowire material layer, and nanowire material layers positioned between adjacent sacrificial material layers; forming a hard mask layer on the stacked material structure, wherein the hard mask layer exposes part of the sacrificial material layer; and taking the hard mask layer as a mask, removing part of the stacked material structure until the surface of the substrate is exposed, forming a second opening in the stacked material structure, and forming the initial stacked structure.

Optionally, the method for forming the first opening includes: forming an initial filling layer in the second opening, wherein the filling layer is also positioned on the side wall of the hard mask layer; after the initial filling layer is formed, removing the hard mask layer, and forming a third opening in the dielectric layer, wherein the third opening exposes the top surface of the initial stacking structure and part of the side wall surface of the initial filling layer; forming a covering layer on the inner wall surface of the third opening, wherein the covering layer forms a fourth opening in the dielectric layer; and removing the covering layer and the initial stacking structure at the bottom of the fourth opening until the surface of the substrate is exposed, and forming a first opening in the dielectric layer.

Optionally, after the forming the isolation structure, the method further includes: removing part of the initial filling layer, and forming a filling layer in the second opening, wherein the filling layer is respectively positioned on the side wall surface of the first bottom layer nanowire and the side wall surface of the second bottom layer nanowire; after forming the filling layer, removing the covering layer; after the covering layer is removed, removing the first sacrificial layer and the second sacrificial layer to form a first nano structure and a second nano structure, forming first grid openings between adjacent first nanowires and between the first nanowires and the first bottom nanowires, and forming second grid openings between adjacent second nanowires and between the second nanowires and the second bottom nanowires; forming a gate structure in the first gate opening and in the second gate opening, the gate structure crossing the isolation structure.

Optionally, after forming the isolation structure and before removing the initial filling layer, the method further includes: forming an initial protective layer on the isolation structure and the capping layer; and etching back the covering layer and the initial protective layer until the surface of the initial filling layer is exposed, and forming protective layers on the isolation structure, the initial first nano structure and the initial second nano structure.

Optionally, the material of the protective layer is different from the material of the initial filling layer.

Optionally, the material of the cover layer is different from the material of the initial filling layer.

Optionally, the material of the hard mask layer is different from the material of the initial filling layer.

Optionally, the material of the initial filling layer comprises a dielectric material, and the dielectric material comprises silicon oxide.

Optionally, the thickness of the cover layer ranges from 10nm to 100 nm.

Optionally, the process of forming the capping layer includes an atomic layer deposition process.

Optionally, the isolation structure includes a first isolation layer and a second isolation layer located on the first isolation layer; the first isolation layer is positioned between the first bottom layer nanowire and the second bottom layer nanowire, and the second isolation layer is positioned between the first nanowire and the second nanowire.

Optionally, the method for forming the first barrier layer and the second barrier layer includes: forming a first isolation layer in the first opening, wherein the first isolation layer exposes the first nanowire side wall and the second nanowire side wall; removing part of the first nanowire and the second nanowire, forming a first groove on the side wall of the first nanowire, and forming a second groove on the side wall of the second nanowire; and forming a first barrier layer in the first groove and forming a second barrier layer in the second groove.

Optionally, the material of the first isolation layer is different from the material of the cover layer; the material of the second isolation layer is different from the material of the cover layer.

Optionally, the material of the first isolation layer includes a dielectric material, and the dielectric material includes silicon oxide; the material of the second isolation layer comprises a dielectric material, and the dielectric material comprises silicon oxide; the material of the cover layer comprises a dielectric material, and the dielectric material comprises silicon nitride.

Optionally, the method for forming the second isolation layer includes: forming an isolation material layer on the first isolation layer; and etching back the isolation material layer to form a second isolation layer.

Optionally, the method for forming the first isolation layer includes: forming an isolation material layer in the first opening; and etching back the isolation material layer to form a first isolation layer.

Optionally, the material of the first barrier layer includes a dielectric material, and the dielectric material includes silicon nitride or silicon oxycarbide; the material of the second barrier layer comprises a dielectric material, and the dielectric material comprises silicon nitride or silicon oxycarbide.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

according to the semiconductor structure in the technical scheme, the first barrier layer is arranged between the first nanowire and the isolation structure, and the second barrier layer is arranged between the second nanowire and the isolation structure, so that the first nanostructure and the second nanostructure can be better electrically isolated, a device formed by the first nanostructure and a device formed by the second nanostructure are not easy to leak, and the performance of the semiconductor structure is improved.

According to the forming method of the semiconductor structure, the first barrier layer is formed on the side wall of the first nanowire, the second barrier layer is formed on the side wall of the second nanowire, and the isolation structure is formed in the first opening. The method enables the first nanostructure and the second nanostructure to be better electrically isolated, so that a device formed by the first nanostructure and a device formed by the second nanostructure are not easy to generate the risk of electric leakage, and the performance of the semiconductor structure is improved.

Further, after the initial filling layer is formed in the second opening, the hard mask layer is removed, a third opening exposing the top surface of the initial stacking structure and part of the side wall surface of the initial filling layer is formed in the dielectric layer, a covering layer is formed on the inner wall surface of the third opening, a fourth opening is formed in the dielectric layer, then the covering layer at the bottom of the fourth opening and the initial stacking structure are removed until the substrate surface is exposed, and the first opening is formed in the dielectric layer. The formed covering layer is uniform in thickness, so that the position of the fourth opening is located in the middle of the third opening, the size and the position of the formed first opening can be adjusted through the thickness of the covering layer, the position of the isolation structure formed in the first opening in the follow-up process can be self-aligned, the size of the first nanowire and the size of the second nanowire are uniform, and therefore the performance difference of a device formed by the first nanostructure and a device formed by the second nanostructure is small and easy to control.

Drawings

FIG. 1 is a schematic cross-sectional view of a semiconductor structure in one embodiment;

fig. 2 to 12 are schematic cross-sectional views illustrating a semiconductor structure forming process according to an embodiment of the invention.

Detailed Description

As described in the background, the performance of the existing forked nanoplatelets remains to be improved. The analysis will now be described with reference to specific examples.

FIG. 1 is a cross-sectional view of a semiconductor structure according to an embodiment.

Please refer to fig. 1, which includes: the substrate comprises a substrate 100, wherein the substrate 100 comprises a first area I, a second area II and an isolation area III positioned between the first area I and the second area II; the fin structure is positioned on the first region I and the second region II and comprises a first nanowire 101 and a plurality of second nanowires 102 positioned on the first nanowire 101; the isolation structure 104 is positioned on the isolation region III, and the isolation structure 104 is respectively contacted with the fin structures on the first region I and the second region II; an isolation layer 103 on the first region I and the second region II, the isolation layer 103 being located on a sidewall of the first nanowire 101; a gate structure 105 located on the isolation layer 103, wherein the gate structure 105 surrounds the second nanowire 102, and the gate structure 105 spans the first region I, the second region II, and the isolation region III.

In the semiconductor structure, a device formed in the first region I is a PMOS device, a device formed in the second region II is an NMOS device, and the isolation structure 104 is used for electrically isolating the device in the first region I from the device structure in the second region II.

However, the size of the semiconductor structure is smaller, and thus the size of the isolation structure 104 is also smaller, and the fin structure on the first region I and the fin structure on the second region II are respectively located on two sidewalls of the isolation structure 104, which may cause a risk of leakage of devices located on two sides of the isolation structure 104.

In order to solve the above problems, an embodiment of the present invention provides a semiconductor structure and a method for forming the semiconductor structure, in which a first barrier layer is formed on a sidewall of a first nanowire, and a second barrier layer is formed on a sidewall of a second nanowire, so that the first nanostructure and the second nanostructure can be better electrically isolated from each other, and a device formed by a subsequent first nanostructure and a device formed by a subsequent second nanostructure are less likely to have a risk of leakage, thereby improving performance of the semiconductor structure.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.

Fig. 2 to 12 are schematic cross-sectional views illustrating a semiconductor structure forming process according to an embodiment of the invention.

Referring to fig. 2, a substrate 200 is provided.

The material of the substrate 200 is monocrystalline silicon.

In other embodiments, the substrate may also be a semiconductor material such as polysilicon, germanium, silicon germanium, gallium arsenide, silicon on insulator, or germanium on insulator.

Referring to fig. 3, an initial stacked structure including initial sacrificial layers 202 and initial nanowires 203 between two adjacent initial sacrificial layers 202 is formed on a substrate 200.

In this embodiment, the initial stacked structure further comprises an initial underlying nanowire 201 located between the substrate 200 and the initial sacrificial layer 202.

The initial sacrificial layer 202 is used for forming a first sacrificial layer and a second sacrificial layer; the initial nanowire 203 is used for subsequent formation of a first nanowire and a second nanowire; the initial bottom layer nanowires 201 are used for subsequent formation of first and second bottom layer nanowires.

The material of the initial sacrificial layer 202 comprises a semiconductor material comprising silicon or silicon germanium; the material of the initial nanowire 203 comprises a semiconductor material comprising silicon or silicon germanium; the material of the initial underlying nanowires 201 comprises a semiconductor material comprising silicon or silicon germanium.

In the present embodiment, the material of the initial sacrificial layer 202 includes silicon germanium; the material of the initial nanowire 203 comprises silicon; the material of the initial underlying nanowires 201 comprises silicon.

The material of the initial sacrificial layer 202 is different from that of the initial nanowire 203, and the material of the initial sacrificial layer 202 is different from that of the initial bottom nanowire 201, so that the material of the initial sacrificial layer 202 has a larger etching selection ratio with that of the initial bottom nanowire 201, and the material of the initial sacrificial layer 202 has a larger etching selection ratio with that of the initial nanowire 203, so that when the first sacrificial layer and the second sacrificial layer are removed in the following process, the damage to the first nanowire and the second nanowire can be smaller, the damage to the first bottom nanowire and the second bottom nanowire can be smaller, and a first nanostructure and a second nanostructure with better performance can be formed.

The forming method of the initial stacking structure comprises the following steps: forming a stacked material structure (not shown) on the substrate 200, the stacked material structure including a bottom layer of nanowire material and several layers of sacrificial material on the bottom layer of nanowire material, and layers of nanowire material between adjacent layers of sacrificial material; forming a hard mask layer 204 on the stacked material structure, wherein the hard mask layer 204 exposes a part of the sacrificial material layer; and removing part of the stacked material structure by taking the hard mask layer 204 as a mask until the surface of the substrate 200 is exposed, forming a second opening 205 in the stacked material structure, and forming the initial stacked structure.

The process for removing part of the stacked material structure comprises one or more of a dry etching process and a wet etching process. In this embodiment, the process of removing a portion of the stacked material structure includes a dry etching process, and the dry etching process can form the second opening 205 with a good sidewall morphology, so that the first nanostructure and the second nanostructure formed subsequently have good morphologies and uniform sizes.

The hard mask layer 204 includes silicon oxide or silicon nitride, and in this embodiment, the hard mask layer 204 includes silicon nitride.

With continued reference to fig. 3, a dielectric layer (not shown) is formed on the substrate 200, the dielectric layer being located on the sidewalls of the initial stacked structure.

The material of the dielectric layer comprises a dielectric material, and the dielectric material comprises one or more of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbonitride and silicon oxycarbonitride. In this embodiment, the material of the dielectric layer includes silicon oxide.

Next, a part of the initial stacked structure is removed until the surface of the substrate 200 is exposed, a first opening 209 is formed in the initial stacked structure, and an initial first nanostructure and an initial second nanostructure are formed, wherein the initial first nanostructure comprises a plurality of first sacrificial layers and a first nanowire positioned between the first sacrificial layers on two adjacent sides, and the initial second nanostructure comprises a plurality of second sacrificial layers and a second nanowire positioned between the second sacrificial layers on two adjacent sides. Please refer to fig. 4 to 6 for a process of forming the first opening 209.

Referring to fig. 4, an initial filling layer 206 is formed in the second opening 205, wherein the filling layer 206 is also located on the sidewall of the hard mask layer 204.

The material of the initial fill layer 206 comprises a dielectric material comprising a combination of one or more of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride. In the present embodiment, the material of the initial fill layer 206 includes silicon oxide.

The material of the initial filling layer 206 is different from the material of the hard mask layer 204, so that when the hard mask layer 204 is subsequently removed, the damage of the process for removing the hard mask layer 204 to the initial filling layer 206 is small, and a third opening can be formed in the dielectric layer, so that the top surface of the initial stacking structure and part of the side wall surface of the initial filling layer 206 are exposed by the third opening, and a covering layer and a fourth opening are subsequently formed in the third opening.

Referring to fig. 5, after forming the initial filling layer 206, the hard mask layer 204 is removed, and a third opening (not shown) is formed in the dielectric layer, where the third opening exposes a top surface of the initial stacked structure and a portion of a sidewall surface of the initial filling layer 206; and forming a covering layer 207 on the inner wall surface of the third opening, wherein the covering layer 207 forms a fourth opening 208 in the dielectric layer.

The material of the cap layer 207 is different from the material of the initial fill layer 206.

The material of the capping layer 207 comprises a dielectric material comprising one or a combination of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride. The process of forming the capping layer 207 includes an atomic layer deposition process or a chemical vapor deposition process.

In this embodiment, the material of the capping layer 207 includes silicon nitride; the process of forming the capping layer 207 includes an atomic layer deposition process.

The atomic layer deposition process can form the covering layer 207 with uniform thickness, so that the fourth opening 208 can be located in the middle of the third opening, the size and the position of the subsequently formed first opening can be adjusted through the thickness of the covering layer 207, the position of the subsequently formed isolation structure in the first opening can be self-aligned, the size of the first nanowire and the size of the second nanowire are uniform, and therefore the performance difference between a device formed by the first nanostructure and a device formed by the second nanostructure is small and easy to control.

In this embodiment, the thickness of the capping layer 207 is in the range of 10nm to 100 nm. The covering layer 207 with the thickness range can adjust the size of the fourth opening 208 by adjusting the thickness of the covering layer 207 in the third opening, so that the size and the position of the subsequently formed first opening can be adjusted by the thickness of the covering layer 207, and the position of the subsequently formed isolation structure in the first opening can be self-aligned.

In the present embodiment, the width of the fourth opening 208 ranges from 5nm to 50 nm. The fourth opening 208 with the width within the range enables an isolation structure formed in the first opening subsequently to have a better electrical isolation effect, so that a device formed by the first nanostructure and a device formed by the second nanostructure can be well electrically isolated, and the situation that the device formed by the first nanostructure and the device formed by the second nanostructure are easy to leak due to too small width is avoided.

Referring to fig. 6, the capping layer 207 and the initial stacked structure at the bottom of the fourth opening 208 are removed until the surface of the substrate 200 is exposed, a first opening 209 is formed in the dielectric layer, and an initial first nanostructure and an initial second nanostructure are formed on two sides of the first opening 209, where the initial first nanostructure includes a plurality of first sacrificial layers 302 and a first nanowire 303 located between the first sacrificial layers 302 on two adjacent sides, and the initial second nanostructure includes a plurality of second sacrificial layers 402 and a second nanowire 403 located between the second sacrificial layers 402 on two adjacent sides.

In this embodiment, the initial first nanostructure further comprises a first bottom layer of nanowires 301 located between the substrate 200 and a first sacrificial layer 302; the initial second nanostructure also includes a second underlying nanowire 401 located between the substrate 200 and a second sacrificial layer 402.

The process of removing the capping layer 207 and the initial stacked structure at the bottom of the fourth opening 208 includes one or more of a dry etching process and a wet etching process. In this embodiment, the process of removing the covering layer 207 and the initial stacked structure at the bottom of the fourth opening 208 includes a dry etching process, and the dry etching process can form the first opening 209 with a good sidewall morphology, so that the subsequently formed first nanostructure and the second nanostructure have good morphologies and uniform sizes.

Referring to fig. 7, a first isolation layer 210 is formed in the first opening 209, and the first isolation layer 210 exposes sidewalls of the first nanowire 303 and sidewalls of the second nanowire 403.

In this embodiment, the first isolation layer 210 is located between the first bottom nanowire 301 and the second bottom nanowire 401.

The method for forming the first isolation layer 210 includes: forming an isolation material layer (not shown) in the first opening 209; the isolation material layer is etched back to form a first isolation layer 210.

The material of the first isolation layer 210 comprises a dielectric material comprising a combination of one or more of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride. In the present embodiment, the material of the first isolation layer 210 includes silicon oxide.

The material of the first isolation layer 210 is different from the material of the capping layer 207, so that when the isolation material layer is etched back, the damage of the etch-back process to the capping layer is small, and the capping layer can protect the initial first nanowire structure and the initial second nanowire structure to a certain extent.

Referring to fig. 8, a first barrier layer 211 is formed on the sidewall of the first nanowire 303 exposed by the first opening 209; a second barrier layer 212 is formed on the sidewalls of the second nanowire 403 exposed by the first opening 209.

The method for forming the first barrier layer 211 and the second barrier layer 212 includes: removing a part of the first nanowire 303 and the second nanowire 403, forming a first groove (not shown) on a sidewall of the first nanowire 303, and forming a second groove (not shown) on a sidewall of the second nanowire 403; forming a barrier material layer (not shown) in the first and second grooves; and removing the barrier material layer on the inner wall surface of the second opening until the surface of the first sacrificial layer 302 and the surface of the second sacrificial layer 402 are exposed, forming a first barrier layer 211 in the first groove, and forming a second barrier layer 212 in the second groove.

The depth range of the first groove includes: 1nm to 10 nm; the depth range of the second groove includes: 1nm to 10 nm. The first groove and the second groove within the depth range enable the electric isolation effect of a first barrier layer formed in the first groove subsequently to be good, enable the electric isolation effect of a second barrier layer formed in the second groove subsequently to be good, and meanwhile avoid the situation that the depths of the first groove and the second groove are deep, so that the process for forming the first groove and the second groove is wasted.

The material of the first barrier layer 211 comprises a dielectric material comprising one or more of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, silicon oxycarbide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride in combination; the material of the second barrier layer 212 comprises a dielectric material comprising a combination of one or more of silicon oxide, silicon nitride, silicon oxynitride, silicon oxycarbide, aluminum oxide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride.

In this embodiment, the material of the first barrier layer 211 includes silicon nitride or silicon oxycarbide; the material of the second barrier layer 212 includes silicon nitride or silicon oxycarbide. The silicon nitride or silicon oxycarbide has better electrical isolation effect.

The process for removing a part of the first nanowire 303 and the second nanowire 403 comprises one or more of a dry etching process and a wet etching process; the process for forming the barrier material layer comprises a chemical vapor deposition process or an atomic layer deposition process; the process for removing the barrier material layer on the inner wall surface of the second opening comprises one or more of a dry etching process and a wet etching process.

In this embodiment, the process of removing a portion of the first nanowire 303 and the second nanowire 403 includes a wet etching process, and the material of the initial sacrificial layer 202 has a larger etching selectivity than the material of the initial nanowire 203, so that when the portion of the first nanowire 303 and the second nanowire 403 is removed, the removal process can cause less damage to the first sacrificial layer and the second sacrificial layer, and thus the first groove and the second groove can be formed; the process for forming the barrier material layer comprises a chemical vapor deposition process, and the chemical vapor deposition process can form the barrier material layer with a compact structure and a thicker thickness, so that the barrier material layer can be quickly formed in the first groove and the second groove.

In this embodiment, the process of removing the blocking material layer on the inner wall surface of the second opening includes a dry etching process, and the dry etching process can form the first blocking layer 211 and the second blocking layer 212 having good sidewall morphology, so that when the second isolation layer 213 is formed on the first isolation layer 210 in the following step, the second isolation layer 213 is tightly combined with the first blocking layer 211 and the second blocking layer 212, and thus the first blocking layer 211 and the second blocking layer 212 have a better electrical isolation effect, so that a device formed by the following first nanostructure and a device formed by the following second nanostructure are less prone to risk of leakage.

The thickness range of the first barrier layer 211 is 1nm to 10 nm; the thickness of the second barrier layer 212 ranges from 1nm to 10 nm. The first barrier layer 211 and the second barrier layer 212 having the thickness range have a good electrical isolation effect.

A first barrier layer 211 is formed on the sidewall of the first nanowire 303, a second barrier layer 212 is formed on the sidewall of the second nanowire 403, and then an isolation structure is formed in the first opening 209. The method enables the first nanostructure and the second nanostructure formed subsequently to be better electrically isolated, so that a device formed by the first nanostructure and a device formed by the second nanostructure are not easy to generate the risk of electric leakage, and the performance of the semiconductor structure is improved.

Referring to fig. 9, an isolation structure is formed in the first opening 209.

The isolation structure comprises a first isolation layer 210 and a second isolation layer 213 located on the first isolation layer 210, the second isolation layer 213 being located between the first nanowire 303 and the second nanowire 403.

The method for forming the second isolation layer 213 includes: forming a spacer material layer (not shown) on the first spacer layer 210; the spacer material layer is etched back to form a second spacer 213.

The material of the second isolation layer 213 comprises a dielectric material comprising a combination of one or more of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride. In this embodiment, the material of the second isolation layer 213 includes silicon oxide.

The material of the second isolation layer 213 is different from the material of the cover layer 207, so that when the isolation material layer is etched back, the damage of the etch-back process to the cover layer is small, and the cover layer 207 can protect the initial first nanostructure and the initial second nanostructure to a certain extent.

Referring to fig. 10, an initial protection layer (not shown) is formed on the isolation structure and the capping layer 207; the capping layer 207 and the initial protection layer are etched back until the surface of the initial filling layer 206 is exposed, forming a protection layer 214 on the isolation structures, on the initial first nanostructures and on the initial second nanostructures.

The material of the protection layer 214 is different from the material of the initial fill layer 206 so that the process of etching back the initial protection layer can stop at the surface of the initial fill layer 206.

The material of the protective layer 214 comprises a dielectric material, including a combination of one or more of silicon oxide, silicon nitride, silicon oxynitride, aluminum oxide, aluminum nitride, silicon carbonitride, and silicon oxycarbonitride. In the present embodiment, the material of the protection layer 214 includes silicon nitride.

With continued reference to fig. 10, a portion of the initial filling layer 206 is removed, and a filling layer 216 is formed in the second opening 205, where the filling layer 216 is respectively located on the sidewall surfaces of the first bottom layer nanowire 301 and the second bottom layer nanowire 302.

The fill layer 216 is used for electrical isolation between subsequently formed gate structures and the substrate 200.

The process of removing a portion of the initial fill layer 206 includes an etch-back process.

Referring to fig. 11, after the filling layer 216 is formed, the passivation layer 214 is removed; after the protective layer 214 is removed, the first sacrificial layer 302 and the second sacrificial layer 402 are removed to form a first nanostructure and a second nanostructure, a first gate opening 311 is formed between the adjacent first nanowires 303 and between the first nanowires 303 and the first bottom layer nanowire 301, and a second gate opening 312 is formed between the adjacent second nanowires 403 and between the second nanowires 403 and the second bottom layer nanowire 401.

The process for removing the protection layer 214 includes one or more of a dry etching process and a wet etching process; the process of removing first sacrificial layer 302 and second sacrificial layer 402 includes one or a combination of dry etching and wet etching.

In this embodiment, the process of removing the protection layer 214 includes a dry etching process; the process for removing the first sacrificial layer 302 and the second sacrificial layer 402 includes a wet etching process, and the wet etching process can remove the first sacrificial layer 302 and the second sacrificial layer 402 cleanly, and has less damage to the first nanowire 303, the second nanowire 403, the first bottom nanowire 301, and the second bottom nanowire 401.

Referring to fig. 12, a gate structure 220 is formed in the first gate opening 311 and the second gate opening 312, wherein the gate structure 220 crosses the isolation structure.

The gate structure 220 includes: a gate dielectric layer (not shown) and a gate layer (not shown) on the gate dielectric layer. In this embodiment, the gate structure further includes a work function layer (not shown), and the work function layer is located between the gate dielectric layer and the gate electrode layer.

The gate dielectric layer comprises a high dielectric constant material, the dielectric constant of the high dielectric constant material is greater than 3.9, and the high dielectric constant material comprises aluminum oxide or hafnium oxide; the material of the gate layer comprises a metal, and the metal comprises tungsten; the material of the work function layer comprises an N-type work function material or a P-type work function material, the N-type work function material comprises titanium aluminum, and the P-type work function material comprises titanium nitride or tantalum nitride.

Accordingly, an embodiment of the present invention further provides a semiconductor structure, please continue to refer to fig. 12, including:

a substrate 200;

an isolation structure located on the substrate 200;

a first nanowire 303 and a second nanowire 403 respectively located at both sides of the isolation structure;

a first barrier layer 211 between the first nanowire 303 and the isolation structure, and a second barrier layer 212 between the second nanowire 403 and the isolation structure.

In this embodiment, the number of the first nanowires 303 is plural, and the plural first nanowires 303 are separated from each other and form a first nanostructure; the number of the second nanowires 403 is plural, and the plural second nanowires 403 are separated from each other and constitute a second nanostructure.

In this embodiment, the first nanostructure further comprises: a first bottom nanowire 301 positioned between the substrate 200 and the first nanowire 303; the second nanostructure further comprises: a second bottom layer of nanowires 401 located between the substrate 200 and the second nanowires 403; the first bottom layer nanowire 401 and the second bottom layer nanowire 301 are respectively located at two sides of the isolation structure.

In this embodiment, the isolation structure includes a first isolation layer 210 and a second isolation layer 213 disposed on the first isolation layer 210, the first isolation layer 210 is disposed between the first bottom nanowire 301 and the second bottom nanowire 401, and the second isolation layer 213 is disposed between the first nanowire 303 and the second nanowire 403.

In the present embodiment, the material of the first isolation layer 210 includes a dielectric material, and the dielectric material includes silicon oxide; the material of the second isolation layer 213 comprises a dielectric material comprising silicon oxide.

In the present embodiment, the material of the first barrier layer 211 includes a dielectric material, and the dielectric material includes silicon nitride or silicon oxycarbide; the material of the second barrier layer 212 comprises a dielectric material comprising silicon nitride or silicon oxycarbide.

In this embodiment, the method further includes: a gate structure 220 surrounding the first nanowire 303 and the second nanowire 403, and the gate structure 220 straddles the isolation structure.

In the semiconductor structure, the first barrier layer 211 is arranged between the first nanowire 303 and the isolation structure, and the second barrier layer 212 is arranged between the second nanowire 403 and the isolation structure, so that the first nanostructure and the second nanostructure can be better electrically isolated, a device formed by the first nanostructure and a device formed by the second nanostructure are less prone to leakage, and the performance of the semiconductor structure is improved.

Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.