阅读说明：本技术 半导体结构及其形成方法 (Semiconductor structure and forming method thereof ) 是由 王艳良 韩秋华 于 2020-06-05 设计创作，主要内容包括：本发明实施例提供了一种半导体结构及其形成方法,所述方法包括：提供基底,基底包括衬底、位于衬底上的多个伪栅极,以及分别位于各伪栅极两侧的掺杂结构；基底包括隔离区,隔离区的延伸方向与多个伪栅极相交,且至少覆盖部分掺杂结构；在多个伪栅极之间形成层间介质层,层间介质层填充在掺杂结构之间且覆盖掺杂结构；去除隔离区内的伪栅极和层间介质层,形成横切多个伪栅极的横切隔离沟槽；其中,在去除隔离区内的层间介质层时,采用第一工艺去除掺杂结构上方的层间介质层,采用第二工艺去除剩余的层间介质层；第二工艺参数对掺杂结构的损伤小于第一工艺参数对掺杂结构的损伤。本发明实施例用于提高器件的性能。(The embodiment of the invention provides a semiconductor structure and a forming method thereof, wherein the method comprises the following steps: providing a substrate, wherein the substrate comprises a substrate, a plurality of dummy gates positioned on the substrate and doping structures respectively positioned at two sides of each dummy gate; the substrate comprises an isolation region, the extension direction of the isolation region is intersected with the plurality of dummy gates, and at least part of the doped structure is covered; forming an interlayer dielectric layer between the dummy gates, wherein the interlayer dielectric layer is filled between the doping structures and covers the doping structures; removing the dummy gates and the interlayer dielectric layers in the isolation regions to form transverse cutting isolation grooves transversely cutting the dummy gates; when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the rest interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure. The embodiment of the invention is used for improving the performance of the device.)

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

providing a base, wherein the base comprises a substrate, a plurality of dummy gates positioned on the substrate and doping structures respectively positioned at two sides of each dummy gate; the substrate comprises an isolation region, the extension direction of the isolation region is intersected with the plurality of dummy gates, and at least part of the doped structure is covered;

forming an interlayer dielectric layer between the dummy gates, wherein the interlayer dielectric layer is filled between the doping structures and covers the doping structures;

removing the dummy gates and the interlayer dielectric layers in the isolation region to form transverse cutting isolation grooves transversely cutting the dummy gates;

when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the rest interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure.

2. The method of claim 1, wherein in the step of removing the interlayer dielectric layer above the doped structure by the first process, the interlayer dielectric layer is removed by the first process until a vertical distance between a top surface of the remaining interlayer dielectric layer and a top of the doped structure is 50 to 100 angstroms.

3. The method for forming a semiconductor structure according to claim 2, wherein an etching process is used to remove the interlayer dielectric layer in the isolation region, the first process is an etching process with a first process parameter, and the second process is an etching process with a second process parameter, wherein an etching rate of the etching process with the second process parameter to the doped structure is less than an etching rate of the etching process with the first process parameter to the doped structure.

4. The method of claim 3, wherein the doped structure comprises a doped electrode and a protective layer surrounding the doped electrode, and the etching rate of the protective layer by the etching process with the second process parameter is smaller than the etching rate of the protective layer by the etching process with the first process parameter.

5. The method of claim 4, wherein an etch rate of the doped electrode by the second process parameter etch process is less than an etch rate of the doped electrode by the first process parameter etch process.

6. The method for forming a semiconductor structure according to claim 4, wherein the interlayer dielectric layer is silicon oxide, the protective layer is silicon nitride, and the etching process is a dry etching process;

in the first process parameter, the adopted process gas comprises CF₄、CHF₃Wherein, CF is₄The flow rate of (1) is 80sccm to 120sccm, CHF₃The flow rate of the liquid is 80sccm to 120 sccm;

in the second process parameter, the adopted process gas comprises C₄F₆、C₄F₈Wherein, C₄F₆The flow rate of (C) is 10sccm to 50sccm₄F₈The flow rate of (B) is 10sccm to 50 sccm.

7. The method for forming a semiconductor structure according to claim 6, wherein the dry etching process is an inductive coupling process, and in the inductive coupling process, the dissociation power is 300W to 800W, and the acceleration power is 500W to 1000W.

8. The method of claim 1, wherein the base further comprises a discrete fin raised above the substrate, the fin having a through-slot; the plurality of dummy gates cross the fin portion, and the doping structure fills the through groove of the fin portion; in the step of removing the interlayer dielectric layer above the doped structure by adopting the first process, the interlayer dielectric layer is removed by adopting the first process until the distance between the top surface of the residual interlayer dielectric layer and the top surface of the fin part is 50-100 angstroms.

9. The method for forming a semiconductor structure according to claim 1, wherein in the step of removing the dummy gate and the interlayer dielectric layer in the isolation region, a dry etching process with a third process parameter is used to remove the dummy gate in the isolation region.

10. The method of claim 9, wherein the third process parameter is a chlorine-containing gas comprising Cl₂Said Cl₂The flow rate of (B) is 0.1sccm to 300 sccm.

11. The method for forming the semiconductor structure according to claim 4, wherein the substrate further comprises a side wall located between the doped structure and the dummy gate, and the material of the side wall is the same as that of the protective layer of the doped structure;

and in the step of removing the interlayer dielectric layer above the doped structure by adopting a first process, part of the side wall in the isolation region is also removed at the same time.

12. The method of claim 1, wherein the removing the interlayer dielectric layer over the doped structure by the first process further simultaneously removes a portion of the thickness of the dummy gate in the isolation region.

13. The method of forming a semiconductor structure of claim 1, wherein said step of forming a cross-cut isolation trench that cross-cuts said plurality of dummy gates is further followed by:

and removing part of the side wall in the isolation region by adopting a dry etching process with fourth process parameters.

14. The method of forming a semiconductor structure of claim 1, wherein said step of forming a cross-cut isolation trench that cross-cuts said plurality of dummy gates is further followed by:

and forming a transverse isolation structure filled in the transverse isolation groove.

15. The method for forming a semiconductor structure according to claim 1, wherein in the step of providing a substrate, a hard mask layer is further formed on the dummy gates, and after the step of forming an interlayer dielectric layer between the plurality of dummy gates and before the step of removing the dummy gates and the interlayer dielectric layer in the isolation region, the method further comprises:

and removing the hard mask layer and part of the interlayer dielectric layer in the isolation region to expose the dummy gate in the isolation region.

16. A semiconductor structure, comprising:

the substrate comprises a substrate, a plurality of dummy gates positioned on the substrate and doping structures respectively positioned at two sides of each dummy gate;

the interlayer dielectric layer is positioned among the plurality of dummy gates and covers at least part of the doping structure;

and the transverse isolation groove is positioned on the substrate, isolates the plurality of dummy gates and the interlayer dielectric layer between the plurality of dummy gates and exposes at least part of the doped structure.

17. The semiconductor structure of claim 16, wherein the doped structure comprises a doped electrode and a protective layer surrounding between the doped electrode and the interlevel dielectric layer, the cross-cut isolation trench exposing the protective layer of the doped structure.

18. The semiconductor structure of claim 16, wherein the base further comprises a discrete fin raised above the substrate, the plurality of dummy gates crossing over the fin; the doped structure is located on the fin portion.

19. The semiconductor structure of claim 16, wherein the substrate further comprises a sidewall spacer located between the doped structure and the dummy gate, and a material of the sidewall spacer is the same as a material of the protective layer of the doped structure.

20. The semiconductor structure of claim 16, wherein a hard mask layer is further disposed on the dummy gate, and the interlayer dielectric layer is flush with the hard mask layer.

Technical Field

Embodiments of the present invention relate to the field of semiconductor manufacturing, and in particular, to a semiconductor structure and a method for forming the same.

Background

In Semiconductor manufacturing, as the feature size of an integrated circuit is continuously reduced along with the development trend of a very large scale integrated circuit, the channel length of a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) is continuously shortened in order to adapt to the smaller feature size. However, as the Channel length of the device is shortened, the distance between the source and the drain of the device is also shortened, so the control capability of the gate structure to the Channel is deteriorated, the difficulty of the gate voltage to pinch off the Channel is increased, and the sub-threshold leakage (SCE), which is a so-called Short Channel effect, is more likely to occur.

Therefore, in order to reduce the influence of short channel Effect, the semiconductor process gradually starts to transition from planar MOSFET to three-dimensional Transistor with higher efficiency, such as Fin-Field-Effect Transistor (FinFET). In the FinFET, the gate structure can control the ultrathin body (fin part) at least from two sides, compared with a planar MOSFET, the gate structure has stronger control capability on a channel, can well inhibit a short-channel effect, and has better compatibility with the existing integrated circuit manufacturing.

However, the performance of the devices formed by the existing semiconductor process is not good.

Disclosure of Invention

Embodiments of the present invention provide a semiconductor structure and a method for forming the same, which optimize the performance of the semiconductor structure.

To solve the above problems, an embodiment of the present invention provides a method for forming a semiconductor structure, including: providing a base, wherein the base comprises a substrate, a plurality of dummy gates positioned on the substrate and doping structures respectively positioned at two sides of each dummy gate; the substrate comprises an isolation region, the extension direction of the isolation region is intersected with the plurality of dummy gates, and at least part of the doped structure is covered; forming an interlayer dielectric layer between the dummy gates, wherein the interlayer dielectric layer is filled between the doping structures and covers the doping structures; removing the dummy gates and the interlayer dielectric layers in the isolation region to form transverse cutting isolation grooves transversely cutting the dummy gates; when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the rest interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure.

Correspondingly, an embodiment of the present invention further provides a semiconductor structure, including: the substrate comprises a substrate, a plurality of dummy gates positioned on the substrate and doping structures respectively positioned at two sides of each dummy gate; the interlayer dielectric layer is positioned among the plurality of dummy gates and covers a part of the doped structure; and the transverse isolation groove is positioned on the substrate, isolates the plurality of dummy gates and the interlayer dielectric layer between the plurality of dummy gates and exposes at least part of the doped structure.

Compared with the prior art, the technical scheme of the embodiment of the invention has the following advantages:

in the embodiment of the invention, when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the residual interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure, so that the damage to the doped structure in the isolation region in the step is reduced, and the performance of the device is improved.

Drawings

Fig. 1 to 4 are schematic structural diagrams corresponding to steps in a method for forming a semiconductor structure;

fig. 5 to 13 are schematic structural diagrams corresponding to steps in a method for forming a semiconductor structure according to an embodiment of the invention;

fig. 14 to 17 are schematic structural views of a semiconductor structure according to an embodiment of the invention.

Detailed Description

As can be seen from the background art, the devices formed by the prior art process still have poor performance. The reason for the poor performance of the device is analyzed in combination with a method for forming a semiconductor structure.

Referring to fig. 1 to 4, schematic structural diagrams corresponding to steps in a method for forming a semiconductor structure are shown.

As shown in fig. 1 to 2, wherein fig. 2 is a cross-sectional view along direction AA' in fig. 1, a base 100 is provided, and the base includes a substrate 101, a plurality of dummy gates 120 located on the substrate, and doped structures 130 respectively located at two sides of each dummy gate 120; the substrate 100 includes an isolation region 10A, and an extension direction of the isolation region 10A intersects with the plurality of dummy gates 120 and at least partially covers the doped structure 130.

As shown in fig. 3, an interlayer dielectric layer 140 is formed between the dummy gates 120, and the interlayer dielectric layer 140 fills between the doped structures 130 and covers the doped structures 130.

As shown in fig. 4, the dummy gate and the interlayer dielectric layer in the isolation region 10A are removed to form a cross-cut isolation trench 150 crossing the plurality of dummy gates 120.

The inventors have found that the device formed by the above method has poor performance because the doped structure in the isolation region 10A is easily damaged or even removed during the formation of the lateral isolation trench 150, which causes damage to the device structure and reduces the device performance.

Accordingly, embodiments of the present invention provide a semiconductor structure and a method for forming the same, including: providing a base, wherein the base comprises a substrate, a plurality of dummy gates positioned on the substrate and doping structures respectively positioned at two sides of each dummy gate; the substrate comprises an isolation region, the extension direction of the isolation region is intersected with the plurality of dummy gates, and at least part of the doped structure is covered; forming an interlayer dielectric layer between the dummy gates, wherein the interlayer dielectric layer is filled between the doping structures and covers the doping structures; removing the dummy gates and the interlayer dielectric layers in the isolation region to form transverse cutting isolation grooves transversely cutting the dummy gates; when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the rest interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure.

In the embodiment of the invention, when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the residual interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure, so that the damage to the doped structure in the isolation region in the step is reduced, and the performance of the device is improved.

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

Fig. 5 to fig. 13 are schematic structural diagrams corresponding to steps in an embodiment of a method for forming a semiconductor structure according to the present invention.

Referring to fig. 5 to 6, a base 200 is provided, where the base 200 includes a substrate 201, a plurality of dummy gates 220 located on the substrate 201, and doping structures 230 respectively located at two sides of each dummy gate 220; the substrate 200 includes an isolation region 20A (indicated by a dashed box), and an extension direction of the isolation region 20A intersects with the plurality of dummy gates 220 and covers at least a portion of the doped structure 230.

The substrate 200 is used to provide support for other structures. In the embodiment of the present invention, the material of the substrate 200 may be silicon. In other embodiments, the material of the substrate can also be germanium, silicon carbide, gallium arsenide, or indium gallium arsenide, and the substrate can also be a silicon-on-insulator substrate or a germanium-on-insulator substrate. The material of the substrate may be a material suitable for process requirements or easy integration. An interface layer may also be formed on the surface of the substrate 200, and the material of the interface layer is silicon oxide, silicon nitride, silicon oxynitride, or the like.

The dummy gate 220 occupies a space for a metal gate structure formed in a subsequent process. The dummy gate 220 may be polysilicon, and in other embodiments, the material of the dummy gate may also be silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon carbonitride, silicon oxycarbonitride, or amorphous carbon.

In the device structure forming process, in order to simultaneously form a plurality of device structures, a plurality of parallel dummy gates 220 are generally simultaneously formed on the substrate, so that corresponding processing is simultaneously performed in the device forming process, and the process flow is simplified.

In the present embodiment, the base further includes a discrete fin 202 protruding from the substrate. The fin part is provided with a through groove for cutting off the fin part so as to provide a process space for the doping structure. The material of the fin 202 may be the same as that of the substrate 201, or may be different from that of the substrate 201. The dummy gate 220 crosses over the discrete fin 202, so that the fin 202 is used as a channel structure for device control. The doping structure 230 is filled in the through groove of the fin 202 and is used for providing a source/drain electrode for a device structure, so that corresponding device control is realized. In the embodiment of the present invention, the doped structure 230 includes a doped electrode 232 and a protection layer 231 surrounding the doped electrode. The doped electrode is used as a source/drain electrode, and the protective layer 231 is used for protecting the doped electrode 232 and preventing the doped electrode 232 from being damaged in the related process.

The material of the doped electrode 232 may be a doped semiconductor material, such as a polysilicon doped material, a germanium doped material, and the like, the material of the protective layer 231 may be silicon nitride, and in other embodiments, the protective layer 231 may also be one or more of silicon carbide, silicon carbonitride, silicon oxycarbonitride, silicon oxynitride, boron nitride, and boron carbonitride.

In the embodiment of the present invention, a hard mask layer 240 may be further formed on the dummy gate. The hard mask layer 240 is used to protect the dummy gate 220, the hard mask layer 240 may be made of silicon nitride, and in other embodiments, the hard mask layer 240 may also be made of silicon oxynitride.

Side walls 221 are formed on two sides of the dummy gate 220, and the side walls 221 may define a formation region of the doped electrode 232. In this embodiment, the sidewall spacers 221 are located between the doped structure 230 and the dummy gate 220, and the material of the sidewall spacers 221 may be silicon nitride. In other embodiments of the present invention, the sidewall spacers 221 may also be one or more of silicon oxide, silicon nitride, silicon carbide, silicon carbonitride, silicon oxycarbonitride, silicon oxynitride, boron nitride, and boron carbonitride.

The substrate 200 includes an isolation region 20A, an extending direction of the isolation region 20A intersects with the plurality of dummy gates 220, and optionally, the plurality of dummy gates 220 are arranged in parallel, and the extending direction of the isolation region 20A is perpendicular to the extending direction of the plurality of parallel dummy gates 220. The isolation region 20A is a region of the substrate for forming a cross-cut isolation trench, and the region covers a part of the structure of the dummy gates 220 and at least covers a part of the doped structure 230 and a part of the space between the dummy gates 220, so as to form a cross-cut isolation trench in the isolation region 20A through a subsequent process.

The width of the isolation region 20A should not be too large or too small, and if the width of the isolation region 20A is too large, the width of a subsequently formed transverse isolation trench is also correspondingly too large, which occupies too much space and is not beneficial to reducing the size of a semiconductor structure; if the width of the isolation region 20A is too small, the width of the subsequently formed transverse isolation trench is also too small to perform the function of isolating devices. Accordingly, the width of the isolation region 20A may be 10 nm to 30 nm.

Referring to fig. 7, an interlayer dielectric layer 250 is formed between the plurality of dummy gates 220, and the interlayer dielectric layer 250 fills between the doped structures 230 and covers the doped structures 230.

The interlayer dielectric layer 250 is filled around the doped structures 230 and covers the doped structures 230, for protecting the device structures and providing support and isolation for the device structures.

The material of the interlayer dielectric layer 250 may be an insulating material. In this embodiment, the interlayer dielectric layer 250 is made of silicon oxide. In other embodiments, the interlayer dielectric layer may also be made of other dielectric materials such as silicon nitride or silicon oxynitride.

Specifically, in this step, the process of forming the interlayer dielectric layer 250 may include: depositing an interlayer dielectric material layer between the plurality of dummy gates, wherein the interlayer dielectric material layer completely fills gaps between the dummy gates and completely covers the dummy gates; and grinding and removing the interlayer dielectric material layer on the pseudo gate to form an interlayer dielectric layer with a plane surface.

The interlayer dielectric material layer may be formed by a Chemical Vapor Deposition (CVD) process.

In the step of grinding and removing the interlayer dielectric material layer on the dummy gate, the grinding stop layer may be the dummy gate or another structure on the dummy gate. In the embodiment of the present invention, a hard mask layer is further formed on the dummy gate, and the hard mask layer is used as a stop layer for polishing, specifically, the step of removing the interlayer dielectric material layer on the dummy gate by polishing is to remove the interlayer dielectric material layer on the hard mask layer, and the interlayer dielectric layer is flush with the top surface of the hard mask layer.

Referring to fig. 8, the hard mask layer and a portion of the interlayer dielectric layer in the isolation region 20A are removed to expose the dummy gate in the isolation region 20A.

The hard mask layer in the isolation region 20A is removed to expose the dummy gate 220 in the isolation region 20A, thereby facilitating the subsequent etching of the corresponding dummy gate 220. Based on the need of removing the interlayer dielectric layer 250, this step simultaneously removes a portion of the interlayer dielectric layer in the isolation region 20A, so as to facilitate the subsequent processes.

Wherein, the hard mask layer and a part of the interlayer dielectric layer 250 can be removed by adopting a dry etching processThe corresponding process gas may be a fluorine-containing gas, such as CF₄、CHF₃And simultaneously removing the hard mask layer and part of the interlayer dielectric layer in the isolation region.

Referring to fig. 9 to 11, removing the dummy gates and the interlayer dielectric layer in the isolation region to form a cross-cut isolation trench W that cross-cuts the plurality of dummy gates;

in this step, the interlayer dielectric layer in the isolation region may be removed first (as shown in fig. 9 and 10), and then the dummy gate in the isolation region may be removed (as shown in fig. 11). It should be noted that, during the process of removing the interlayer dielectric layer in the isolation region, the dummy gate 220 (as shown in fig. 10) with a partial thickness in the isolation region may also be removed at the same time, so as to reduce the process cost of subsequently removing the dummy gate in the isolation region. In other embodiments of the present invention, the dummy gate in the isolation region may be removed first, and then the interlayer dielectric layer in the isolation region may be removed.

When the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process (as shown in fig. 9), and the residual interlayer dielectric layer is removed by adopting a second process (as shown in fig. 10); the damage of the second process parameter to the doped structure 230 is smaller than the damage of the first process parameter to the doped structure 230, so that the damage to the doped structure 230 located in the isolation region 20A in this step is reduced, and the performance of the device is improved.

The transverse isolation trench W is used for cutting off the dummy gate in the extension direction of the dummy gate so as to isolate a plurality of corresponding device structures in the extension direction of the dummy gate. It should be noted that, in order to facilitate the semiconductor integration process, the cross-cut isolation trench W simultaneously cuts off a plurality of parallel dummy gates in a direction perpendicular to the extension direction of the dummy gates, so as to simultaneously isolate a plurality of device structures.

And the transverse cutting isolation trench W also cuts off the interlayer dielectric layer at the same time, so that a larger process opening can be provided when a transverse cutting isolation structure is formed subsequently, and the quality of the transverse cutting isolation structure is improved.

In the embodiment of the present invention, the interlayer dielectric layer above the doped structure 230 is removed by using the first process, and part of the sidewall in the isolation region is also removed at the same time. It should be noted that the material based on the sidewall is the same as the protective layer of the doped structure, the thickness of the sidewall that is removed is limited to the thickness that is removed by the first process, and the removal of the remaining interlayer dielectric layer by the second process cannot be performed any more.

In the embodiment of the invention, the thickness of the interlayer dielectric layer 250 removed by the first process is smaller for process control. Specifically, the interlayer dielectric layer is removed by adopting a first process until the vertical distance between the top surface of the residual interlayer dielectric layer and the top of the doped structure is 50-100 angstroms, so that the doped structure is prevented from being damaged by the first process.

Considering that the doped structure does not have a flat top surface and the corresponding distance is not easy to control, in the embodiment of the present invention, the top surface of the fin portion may be further used as a reference for control. Specifically, the interlayer dielectric layer is removed by adopting a first process until the distance between the top surface of the remaining interlayer dielectric layer and the top surface of the fin portion is 50-100 angstroms in consideration of the fact that the height of the doped structure is approximately the same as the height of the top surface of the fin portion, so that the doped structure is prevented from being damaged by the first process.

In the embodiment of the present invention, the first process and the second process may be the same process and have different process parameters, so as to facilitate the process flow. The process for removing the interlayer dielectric layer in the isolation region may be an etching process, the first process may be an etching process with first process parameters, and the second process may be an etching process with second process parameters, wherein the etching rate of the etching process with the second process parameters to the doped structure is less than the etching rate of the etching process with the first process parameters to the doped structure, so that the damage of the etching process to the doped structure is reduced.

It can be understood that the smaller the etching rate of the etching process with the second process parameter to the doped structure is, the less the damage to the doped structure is, in an optimal example, the etching rate of the etching process with the second process parameter to the doped structure may be close to 0, so as not to damage the doped structure.

In the embodiment of the present invention, the doped structure includes a doped electrode and a protective layer surrounding the doped electrode, and correspondingly, in the etching process, the protective layer is first contacted with the etching process, so that the doped structure of the embodiment of the present invention is not damaged, and the etching rate of the etching process with the second process parameter on the protective layer may be set to be smaller than the etching rate of the etching process with the first process parameter on the protective layer.

In a further example, if the second process parameter inevitably damages the protection layer, the etching rate of the etching process with the second process parameter on the doped electrode may be further set to be smaller than the etching rate of the etching process with the first process parameter on the doped electrode, so as to reduce the damage of the etching process on the doped electrode.

In the embodiment of the present invention, the interlayer dielectric layer 250 is silicon oxide, the protective layer 231 is silicon nitride, the etching process may be a dry etching process, and correspondingly, in the first process parameter, the process gas includes CF₄、CHF₃Wherein, CF is₄The flow rate of (1) is 80sccm to 120sccm, CHF₃The flow rate of the silicon nitride is 80 sccm-120 sccm, so that the silicon oxide and the silicon nitride are removed simultaneously; in the second process parameter, the process gas comprises C₄F₆、C₄F₈Wherein, C₄F₆The flow rate of (C) is 10sccm to 50sccm₄F₈The flow rate of (a) is 10sccm to 50sccm, thereby realizing the separate removal of silicon oxide.

Wherein, in the first process parameter, the process gas can also further comprise O₂The corresponding flow rate is 10sccm to 30sccm, so that the etching rate is improved; in the second process parameter, the process gas may further include O₂Corresponding toThe flow rate is 10 sccm-100 sccm, Ar is 500 sccm-1000 sccm, and argon and helium play a role in promoting C₄F₆Or C₄F₈The second process parameter may be a pressure of 10mT to 100mT to improve the etching direction sagging property, a source power (source power) of 10W to 100W, and a bias voltage (bias voltage) of 500V to 1500V.

In the embodiment of the invention, the dry etching process can be an inductive coupling process, wherein in the inductive coupling process, the dissociation power is 300-800W, and the acceleration power is 500-1000W.

In the process of removing the dummy gate in the isolation region (as shown in fig. 11), the same processes as the first and second processes and the third process parameters different from the first and second processes may be adopted, so that the process flow may be simplified.

Specifically, a dry etching process with a third process parameter may be used to remove the dummy gate in the isolation region. Correspondingly, in the step of removing the dummy gate in the isolation region by using the dry etching process with the third process parameter, the process gas used is a chlorine-containing gas, and the chlorine-containing gas may include Cl₂Said Cl₂The flow rate of (B) is 0.1sccm to 300 sccm.

In the embodiment of the present invention, after the dummy gate in the isolation region is further removed, a dry etching process with a fourth process parameter is further adopted to remove a part of the sidewall in the isolation region (refer to fig. 12), so as to provide a larger process space for a subsequent forming process of the transverse cutting isolation structure.

It should be noted that, based on the same material of the side wall and the protective layer, the side wall is removed only by a small amount in this step, so as to avoid damage to the doped electrode in the protective layer. Specifically, in the dry etching process with the fourth process parameter, the process gas may include: CH (CH)₂F₂The corresponding flow rate can be 10sccm to 100 sccm; o is₂The corresponding flow rate can be 10sccm to 50 sccm; ar, corresponding to a flow rate of 50sccm～100sccm。

Referring to fig. 13, a cross-cut isolation structure 260 filled in the cross-cut isolation trench is formed.

Isolation of the device structure is achieved by forming a lateral isolation structure 260 that fills the lateral isolation trench. The material of the transverse isolation structure 260 may be an insulating material, so as to electrically isolate the device structures.

The material of the transverse cutting isolation structure 260 may be one or more of silicon nitride, silicon oxide, silicon carbide, silicon carbonitride, silicon oxycarbonitride, silicon oxynitride, boron nitride, and boron carbonitride. In an embodiment of the present invention, the material of the lateral isolation structure 260 may be silicon nitride.

In an embodiment of the present invention, the process of forming the lateral isolation structure 260 filling the lateral isolation trench may include: forming a transverse cutting isolation material which completely covers one side of the substrate with the transverse cutting isolation groove; the substrate surface is polished to remove the cross-cut isolation material, and the cross-cut isolation material in the cross-cut isolation trench is retained as the cross-cut isolation structure 260.

The process of forming the transverse isolation material may be a Flow Chemical Vapor Deposition (FCVD) process. The polishing process may be a chemical mechanical polishing process to form good topography into the lateral isolation structures 260.

In the embodiment of the invention, when the interlayer dielectric layer in the isolation region is removed, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the residual interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure, so that the damage to the doped structure in the isolation region in the step is reduced, and the performance of the device is improved.

An embodiment of the present invention further discloses a semiconductor structure, referring to fig. 14 to 17, wherein fig. 15 is a cross-sectional view along CC ' in fig. 14, fig. 16 is a cross-sectional view along DD ' in fig. 14, and fig. 17 is a cross-sectional view along EE ' in fig. 14, including:

the substrate 300, the substrate 300 includes a substrate 301, a plurality of dummy gates 320 located on the substrate 301, and doping structures 330 respectively located at two sides of each dummy gate 320; an interlayer dielectric layer 350 positioned between the plurality of dummy gates 320, wherein the interlayer dielectric layer 350 covers at least a portion of the doped structure 330; a cross-cut isolation trench 360 on the substrate 300, the cross-cut isolation trench 360 isolating the plurality of dummy gates 320 and the interlayer dielectric layer 350 between the plurality of dummy gates 320 and exposing at least a portion of the doped structure.

The substrate 301 is used to provide support for other structures. In the embodiment of the present invention, the material of the substrate 301 may be silicon. In other embodiments, the material of the substrate can also be germanium, silicon carbide, gallium arsenide, or indium gallium arsenide, and the substrate can also be a silicon-on-insulator substrate or a germanium-on-insulator substrate. The material of the substrate may be a material suitable for process requirements or easy integration. The surface of the substrate 301 may also be formed with an interface layer, and the interface layer is made of silicon oxide, silicon nitride, silicon oxynitride, or the like.

The dummy gate 320 occupies a space for a metal gate structure formed in a subsequent process. The dummy gate may be polysilicon, and in other embodiments, the material of the dummy gate may also be silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, silicon carbonitride, silicon oxycarbonitride, or amorphous carbon.

In order to simultaneously establish a plurality of device structures, a plurality of parallel dummy gates 320 are generally simultaneously established on the substrate, so that corresponding processes can be simultaneously performed in the device formation process, and the process flow can be simplified.

In the embodiment of the present invention, the base further includes a discrete fin 302 protruding from the substrate 301, the fin has a through slot, and the plurality of dummy gates 320 cross over the fin 302; the doped structure 330 fills the through-trench of the fin 302.

The doped structure 330 is located on the fin 302, so that the fin 301 is used as a channel structure for device control. The doped structure 330 is used to provide source and drain electrodes for the device structure, thereby implementing corresponding device control. In the embodiment of the present invention, the doped structure 330 includes a doped electrode 332 and a protection layer 331 surrounding the doped electrode. The doped electrode 332 is used as a source/drain electrode, and the protection layer 331 is used for protecting the doped electrode 332 so as to prevent the doped electrode 332 from being damaged in the related process.

The material of the doped electrode 332 may be a doped semiconductor material, such as a polysilicon doped material, a germanium doped material, etc., the material of the protection layer 331 may be silicon nitride, and in other embodiments, the protection layer may also be one or more of silicon carbide, silicon carbonitride, silicon oxycarbonitride, silicon oxynitride, boron nitride, and boron carbonitride.

In the embodiment of the present invention, a hard mask layer 340 may be further disposed on the dummy gate 320, and the interlayer dielectric layer 350 is flush with the hard mask layer 340. The hard mask layer 340 is used to protect the dummy gate 320, the hard mask layer 340 may be made of silicon nitride, and in other embodiments, the hard mask layer may also be made of silicon oxynitride.

Optionally, the substrate 300 further includes a sidewall 321 located between the doped structure 330 and the dummy gate 320, and the material of the sidewall 321 is the same as that of the protection layer 331 of the doped structure 330.

Optionally, the substrate 300 may further include side walls 321 located between the doped structure 330 and the dummy gate 320, where the side walls 321 are disposed at two sides of the dummy gate 320, and the side walls 321 may define a formation region of the doped electrode 332. The material of the sidewall spacers 321 may be silicon nitride. In other embodiments of the present invention, the material of the sidewall may also be one or more of silicon oxide, silicon nitride, silicon carbide, silicon carbonitride, silicon oxycarbonitride, silicon oxynitride, boron nitride, and boron carbonitride.

The substrate 300 includes an isolation region 30A, an extending direction of the isolation region 30A intersects with the plurality of dummy gates 320, and optionally, the plurality of dummy gates 320 are arranged in parallel, and the extending direction of the isolation region 30A is perpendicular to the extending direction of the plurality of parallel dummy gates 320. The isolation region 30A is a region of the substrate 300 for forming a cross-cut isolation trench, which covers a portion of the structure of the dummy gates 320 and at least covers a portion of the doped structure 330 and a portion of the space between the dummy gates 320, so as to provide a cross-cut isolation trench in the isolation region 30A.

The width of the isolation region 30A should not be too large or too small, and if the width of the isolation region 30A is too large, the width of the corresponding transverse isolation trench is also too large, which occupies too much space and is not beneficial to reducing the size of the semiconductor structure; if the width of the isolation region 30A is too small, the width of the corresponding cross-cut isolation trench is also too small to perform the function of isolating the device. Accordingly, the width of the isolation region 30A may be 10 nm to 30 nm.

Further, the interlayer dielectric layer 350 may be established around the doped structures 330 and over the doped structures 330 for protecting the device structures and providing support and isolation for the device structures.

The material of the interlayer dielectric layer 350 may be an insulating material. In this embodiment, the interlayer dielectric layer 350 is made of silicon oxide. In other embodiments, the interlayer dielectric layer may also be made of other dielectric materials such as silicon nitride or silicon oxynitride.

The cross isolation trench 360 is used to cut off the dummy gate 320 in the extension direction of the dummy gate 320, so as to isolate a plurality of corresponding device structures in the extension direction of the dummy gate 320. It should be noted that the cross-cut isolation trench 360 exposes a portion of the protection layer 331 of the doped structure 330.

The cross-cut isolation trench 360 also cuts off the interlayer dielectric layer 350, so that a large process opening can be provided when a cross-cut isolation structure is formed, and the quality of the cross-cut isolation structure is improved.

In other embodiments of the present invention, the sidewall spacers 321 with different materials from the doped structure protection layer 331 may also be formed, so as to completely remove the sidewall spacers 321.

Further, the semiconductor structure further comprises: and arranging a transverse isolation structure filled in the transverse isolation groove.

In other embodiments of the present invention, a lateral isolation structure filled in the lateral isolation trench may be further provided to implement isolation of the device structure. The material of the transverse isolation structure can be an insulating material, so that the device structures are electrically isolated from each other. The material of the transverse cutting isolation structure can be one or more of silicon nitride, silicon oxide, silicon carbide, silicon carbonitride, silicon oxycarbonitride, silicon oxynitride, boron nitride and boron carbonitride. In an embodiment of the present invention, a material of the lateral isolation structure may be silicon nitride.

In the embodiment of the invention, in order to avoid damage to the doped structure, the interlayer dielectric layer above the doped structure is removed by adopting a first process, and the residual interlayer dielectric layer is removed by adopting a second process; the damage of the second process parameter to the doped structure is smaller than the damage of the first process parameter to the doped structure, so that the damage to the doped structure in the isolation region is reduced, and the performance of the device is improved.

The semiconductor structure may be formed by the formation method described in the foregoing embodiment, or may be formed by another formation method. For a detailed description of the semiconductor structure in this embodiment, reference may be made to the corresponding description in the foregoing embodiments, and details of this embodiment are not repeated herein.

Although the embodiments of the present invention are disclosed above, the embodiments of the present invention are not limited thereto. Various changes and modifications may be effected therein by one of ordinary skill in the pertinent art without departing from the scope or spirit of the present embodiments, and it is intended that the scope of the present embodiments be defined by the appended claims.