Formation method of semiconductor structure

Abstract

A forming method of a semiconductor structure comprises the steps that a substrate is provided, a mask layer is formed on the substrate, and a mask opening exposing the surface of the substrate is formed in the mask layer; patterning the surface of the substrate along the mask opening to form a notch extending to the bottom of the mask layer on two sides of the mask opening; and patterning the substrate along the notch to form a groove in the substrate. The reliability of the semiconductor structure can be improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor manufacturing, and in particular to a method for forming a semiconductor structure. Background Art

[0002] Deep silicon etching plays a vital role in the integrated circuit manufacturing process. For example, micro-electro-mechanical system (MEMS) devices such as accelerometers, gyroscopes and pressure sensors all rely on high-precision deep silicon etching to form high aspect ratios and vertical sidewalls to ensure device performance and reliability.

[0003] During deep silicon etching, the angle of the photoresist has an important influence on the quality of the final etched structure. The angle of the photoresist sidewall directly affects the morphology of the etched sidewall. Ideally, the photoresist sidewall should be close to 90°. The upright sidewall can provide an accurate mask profile and reduce lateral etching during the etching process. However, in actual processes, due to factors such as photoresist characteristics, exposure and development processes, photoresists often cannot reach the ideal state, thus affecting the final etching quality. In the face of the problem of unsatisfactory photoresist angles, other methods must be explored to compensate and optimize the etching process to ensure high-quality etched structures. Summary of the invention

[0004] The problem solved by the embodiments of the present invention is to provide a method for forming a semiconductor structure, which is beneficial to improving the reliability of the semiconductor structure.

[0005] To solve the above problems, an embodiment of the present invention provides a semiconductor structure, including: providing a substrate, a mask layer formed on the substrate, and a mask opening formed in the mask layer to expose the surface of the substrate; patterning the substrate surface along the mask opening to form a recess at the bottom of the mask layer extending to both sides of the mask opening; and patterning the substrate along the recess to form a groove located in the substrate.

[0006] Optionally, a first etching process is used to pattern the substrate surface along the mask opening to form a recess at the bottom of the mask layer extending to both sides of the mask opening; a second etching process is used to pattern the substrate along the recess to form a groove in the substrate; wherein the lateral etching rate of the first etching process is greater than the lateral etching rate of the second etching process.

[0007] Optionally, the first etching process is an anisotropic dry etching process; and the second etching process is an anisotropic dry etching process.

[0008] Optionally, in the step of patterning the substrate surface along the mask opening using the first etching process, an etching selectivity ratio of the first etching process to the substrate and the mask layer is greater than or equal to 20.

[0009] Optionally, the step of patterning the substrate surface along the mask opening using a first etching process to form a recess at the bottom of the mask layer extending to both sides of the mask opening includes: performing multiple alternating cycles of a first protection step and a first etching step, the first protection step being used to form a first protection layer covering the surface of the recess, and the first etching step being used to etch the first protection layer and the substrate.

[0010] Optionally, the first protection step includes: introducing a first protective gas; and forming a first protective layer on the surface of the recess using the first protective gas.

[0011] Optionally, the first etching step includes: introducing a first etching gas; and etching the first protective layer and the substrate using the first etching gas.

[0012] Optionally, a second etching process is used to pattern the substrate along the recess, and the step of forming a recess in the substrate includes: performing a second protection step and a second etching step in multiple alternating cycles, the second protection step is used to form a second protection layer covering the surface of the recess, and the second etching step is used to etch the second protection layer and the substrate.

[0013] Optionally, the second protection step includes: introducing a second protective gas; and forming a second protective layer on the surface of the groove using the second protective gas.

[0014] Optionally, the second etching step includes: introducing a second etching gas; and etching the second protective layer and the substrate using the second etching gas.

[0015] Optionally, in the step of providing a substrate, the material of the substrate includes silicon.

[0016] Optionally, in the step of providing the substrate, the material of the mask layer includes photoresist or silicon oxide.

[0017] Optionally, after patterning the substrate along the notch to form a groove in the substrate, the forming method further includes: removing the mask layer.

[0018] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:

[0019] In the formation method provided by the embodiment of the present invention, the substrate surface is patterned along the mask opening to form a recess extending to the bottom of the mask layer on both sides of the mask opening, and the substrate is patterned along the recess to form a recess located in the substrate; in the semiconductor process, due to the influence of the process, the side wall of the mask opening usually has a slope, that is, the thickness of the mask layer gradually increases from the side wall of the mask opening to the mask layer. In the embodiment of the present invention, before the recess is formed by patterning the substrate, a recess extending to the bottom of the mask layer on both sides of the mask opening is formed on the substrate surface in advance, and the opening of the recess is expanded outward to the bottom of the mask layer on both sides of the mask opening in advance, so that the mask layer above the boundary of the recess is thicker and the mask layer is convex at the boundary of the recess. Correspondingly, in the process of patterning the substrate along the recess, the mask layer above the boundary of the recess opening is thicker and the boundary of the recess opening also has a convex mask layer protection, so that the mask layer has better protection for the top of the recess opening, so that in the process of patterning the substrate along the recess, it is beneficial to reduce the damage to the side of the recess opening, improve the verticality of the side wall of the recess, and further improve the reliability of the semiconductor structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 to Figure 2 It is a schematic structural diagram corresponding to each step in a method for forming a semiconductor structure;

[0021] Figures 3 to 9 It is a schematic structural diagram corresponding to each step in an embodiment of a method for forming a semiconductor structure of the present invention. DETAILED DESCRIPTION

[0022] As can be seen from the background art, it is currently difficult to ensure the reliability of semiconductor structures. Now, in conjunction with a method for forming a semiconductor structure, the reasons why the reliability of semiconductor structures still needs to be improved are analyzed.

[0023] Figure 1 to Figure 2 The present invention is a schematic structural diagram corresponding to each step in a method for forming a semiconductor structure.

[0024] refer to Figure 1 A substrate 10 is provided, a mask layer 20 is formed on the substrate 10, and a mask opening 21 exposing the surface of the substrate 10 is formed in the mask layer 20.

[0025] refer to Figure 2 , the substrate 10 is patterned along the mask opening 21 to form a groove 11.

[0026] In the semiconductor manufacturing process, due to the influence of the process, the side wall slope of the mask opening 21 is relatively large, that is, the mask layer 20 on both sides of the top of the groove 11 is relatively thin. In the process of etching the substrate 10 along the mask opening 21, the groove 11 is formed by longitudinal etching, and lateral etching will also occur. During the continuous lateral etching, the thinner mask layer 20 on both sides of the mask opening 21 is easily etched away, exposing the top surface of the substrate 10 on both sides of the groove 11, thereby damaging the top of the substrate 10 on both sides of the groove 11, causing defects on the top of the side wall of the groove 11, and affecting the reliability of the semiconductor structure.

[0027] In order to solve the technical problem, an embodiment of the present invention provides a method for forming a semiconductor structure, including: providing a substrate, a mask layer formed on the substrate, and a mask opening formed in the mask layer to expose the surface of the substrate; patterning the substrate surface along the mask opening to form a recess at the bottom of the mask layer extending to both sides of the mask opening; and patterning the substrate along the recess to form a groove located in the substrate.

[0028] In the semiconductor manufacturing process, due to the influence of the process, the side wall of the mask opening usually has a slope, that is, the thickness of the mask layer gradually increases from the side wall of the mask opening to the mask layer. In the embodiment of the present invention, before the groove is formed in the patterned substrate, a recess extending to the bottom of the mask layer on both sides of the mask opening is formed in advance on the substrate surface, and the opening of the groove is expanded to the bottom of the mask layer on both sides of the mask opening in advance, so that the mask layer above the boundary of the groove is thicker, and the mask layer is convex at the boundary of the groove. Correspondingly, in the process of patterning the substrate along the groove, the mask layer above the boundary of the groove opening is thicker, and the boundary of the groove opening also has a protruding mask layer protection, so that the mask layer has better protection for the top of the groove opening, so that in the process of patterning the substrate along the groove, it is beneficial to reduce the damage to the side of the groove opening and improve the verticality of the side wall of the groove, which is beneficial to improve the reliability of the semiconductor structure.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] Figures 3 to 9 It is a schematic structural diagram corresponding to each step in an embodiment of a method for forming a semiconductor structure of the present invention.

[0031] refer to Figure 3 A substrate 100 is provided, a mask layer 200 is formed on the substrate 100 , and a mask opening 210 exposing the surface of the substrate 100 is formed in the mask layer 200 .

[0032] The substrate 100 provides a process operation basis for the formation process of the semiconductor structure.

[0033] In this embodiment, the material of the substrate 100 includes silicon, that is, the substrate 100 is a silicon substrate.

[0034] The mask layer 200 is used as an etching mask for subsequent patterning of the substrate 100 .

[0035] In this embodiment, the material of the mask layer 200 is photoresist.

[0036] The mask layer 200 is formed by using photoresist, and the mask opening 210 can be formed by using light irradiation, and the formation process is simple and easy to operate.

[0037] In other embodiments, the material of the mask layer may also be silicon oxide.

[0038] The mask layer is formed by using silicon oxide, so that a mask opening with good verticality of the opening side wall can be easily formed.

[0039] The mask opening 210 exposes the surface of the substrate 100 , preparing for subsequent patterning of the substrate 100 along the mask opening 210 .

[0040] Combined with reference Figures 4 to 7 , the surface of the substrate 100 is patterned along the mask opening 210 to form a recess 110 at the bottom of the mask layer 200 extending to both sides of the mask opening 210 .

[0041] The notch 110 extends to the bottom of the mask layer 200 on both sides of the mask opening 210. The substrate 100 is subsequently patterned along the mask opening 210 to form a groove. In this way, a notch 110 is formed on the surface of the substrate 100, and the opening of the groove to be formed subsequently is expanded in advance to the bottom of the mask layer 200 on both sides of the mask opening 210, so that the mask layer 200 above the boundary of the notch 110 is thicker, which is beneficial to the protection of the mask layer 200 on the top surface of the substrate 100 on both sides of the groove during the subsequent formation of the groove.

[0042] In this embodiment, a first etching process is used to pattern the surface of the substrate 100 along the mask opening 210 to form a recess 110 at the bottom of the mask layer 200 extending to both sides of the mask opening 210 .

[0043] In this embodiment, the first etching process is an anisotropic dry etching process.

[0044] The process parameters of the anisotropic dry etching process are easy to control, so that the parameters can be well adjusted so that during the etching process, the etching is shallower in the vertical direction and the bottom of the mask layer 200 on both sides of the mask opening 210 is etched in the horizontal direction.

[0045] In the present embodiment, in the step of patterning the surface of the substrate 100 along the mask opening 210 using the first etching process, the etching selectivity ratio of the first etching process to the substrate 100 and the mask layer 200 is greater than or equal to 20, which is beneficial for reducing the damage to the mask layer 200 during the etching process of the substrate 100, thereby forming the recess 110 at the bottom of the mask layer 200 extending to both sides of the mask opening 210 while better retaining the mask layer 200 on both sides of the mask opening 210.

[0046] In this embodiment, the step of patterning the surface of the substrate 100 along the mask opening 210 using a first etching process to form a recess 110 at the bottom of the mask layer 200 extending to both sides of the mask opening 210 includes: performing a first protection step and a first etching step in multiple alternating cycles, the first protection step being used to form a first protection layer 220 covering the surface of the recess 110, and the first etching step being used to etch the first protection layer 220 and the substrate 100.

[0047] The first protection step and the first etching step are performed in multiple alternating cycles. The first protection layer 220 is used to slow down the etching of the lateral substrate 100 during the first etching step to reduce damage to the lateral substrate 100 .

[0048] Specifically, in this embodiment, the first protection step includes: introducing a first protection gas; and forming a first protection layer 220 on the surface of the recess 110 by using the first protection gas.

[0049] In this embodiment, the first etching step includes: introducing a first etching gas; and etching the first protection layer 220 and the substrate 100 using the first etching gas.

[0050] It should be noted that, in this embodiment, the first protection step and the first etching step are performed in multiple alternating cycles, and the order of the first protection step and the first etching step is not limited. As an example, Figures 4 to 7 , alternately cycle through the first protection step (such as Figure 4 As shown), the first etching step (as shown Figure 5 As shown), the first protection step (as Figure 6 As shown), the first etching step (as shown Figure 7 shown).

[0051] Combined with reference Figure 8 and Fig. 9 , the substrate 100 is patterned along the notch 110 to form a groove 130 located in the substrate 100 .

[0052] The groove 130 is used to provide a space for forming subsequent structures.

[0053] In the semiconductor manufacturing process, due to the influence of the process, the sidewall of the mask opening 210 usually has a slope, that is, the thickness of the mask layer 200 gradually increases from the sidewall of the mask opening 210 to the mask layer 200. In this embodiment, before the groove 130 is formed on the patterned substrate 100, a recess 110 extending to the bottom of the mask layer 200 on both sides of the mask opening 210 is formed on the surface of the substrate 100 in advance. Then, the opening of the recess 130 is expanded outward to the bottom of the mask layer 200 on both sides of the mask opening 210 in advance, so that the mask layer 200 above the boundary of the recess 110 is thicker. The mask layer 200 is thick and protrudes at the boundary of the recess 110. Accordingly, in the process of patterning the substrate 100 along the recess 110, the mask layer 200 above the opening boundary of the groove 130 is thicker and the opening boundary of the groove 130 is also protected by the protruding mask layer 200, so that the mask layer 200 can better protect the top of the opening of the groove 130. Therefore, in the process of patterning the substrate 100 along the recess 110, it is beneficial to reduce the damage to the side of the opening of the groove 130, improve the verticality of the side wall of the groove 130, and further help to improve the reliability of the semiconductor structure.

[0054] In this embodiment, the substrate 100 is patterned along the notch 110 by a second etching process to form a groove 130 in the substrate 100 .

[0055] In this embodiment, the lateral etching rate of the first etching process is greater than the lateral etching rate of the second etching process.

[0056] The lateral etching rate of the first etching process is greater than the lateral etching rate of the second etching process, so that the first etching process can be used in advance to form the notch 110 that expands outward relative to the opening of the groove 130 .

[0057] In this embodiment, the second etching process is an anisotropic dry etching process.

[0058] The anisotropic dry etching process has the characteristics of anisotropic etching. Therefore, by selecting the anisotropic dry etching process, the etching is more directional, which is beneficial to improving the opening size accuracy of the groove 130, and the process parameters of the anisotropic dry etching process are easy to control, so that the process parameters of the second etching process can be better controlled to achieve more stable etching.

[0059] In this embodiment, the substrate 100 is patterned along the recess 110 using a second etching process to form a recess 130 in the substrate 100, including: performing a second protection step and a second etching step in multiple alternating cycles, wherein the second protection step is used to form a second protection layer 140 covering the surface of the recess 130, and the second etching step is used to etch the second protection layer 140 and the substrate 100.

[0060] The second protection step and the second etching step are performed in multiple alternating cycles. The second protection layer 140 is used to slow down the etching of the lateral substrate 100 during the second etching step to reduce damage to the lateral substrate 100 , thereby improving the verticality of the sidewall of the groove 130 .

[0061] Specifically, in this embodiment, the second protection step includes: introducing a second protection gas; and forming a second protection layer 140 on the surface of the groove 130 by using the second protection gas.

[0062] In this embodiment, the second etching step includes: introducing a second etching gas; and etching the second protective layer 140 and the substrate 100 using the second etching gas.

[0063] It should be noted that, in this embodiment, the second protection step and the second etching step are performed in multiple alternating cycles, and the order of the second protection step and the second etching step is not limited. As an example, Figures 8 to 9 , alternately cycle to perform the second protection step (such as Figure 8 As shown), the second etching step (as shown Fig. 9 shown).

[0064] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A method for forming a semiconductor structure, characterized in that: include: Providing a substrate, wherein a mask layer is formed on the substrate, and a mask opening is formed in the mask layer to expose the surface of the substrate; Patterning the substrate surface along the mask opening to form a recess at the bottom of the mask layer extending to both sides of the mask opening; The substrate is patterned along the notch to form a groove in the substrate.

2. The method for forming a semiconductor structure according to claim 1, wherein: Patterning the substrate surface along the mask opening using a first etching process to form a recess at the bottom of the mask layer extending to both sides of the mask opening; Patterning the substrate along the notch using a second etching process to form a groove in the substrate; Wherein, the lateral etching rate of the first etching process is greater than the lateral etching rate of the second etching process.

3. The method for forming a semiconductor structure according to claim 2, wherein: The first etching process is an anisotropic dry etching process; The second etching process is an anisotropic dry etching process.

4. The method for forming a semiconductor structure according to claim 2, wherein: In the step of patterning the substrate surface along the mask opening using a first etching process, an etching selectivity ratio of the first etching process to the substrate and the mask layer is greater than or equal to 20.

5. The method for forming a semiconductor structure according to claim 2, wherein: The step of patterning the substrate surface along the mask opening using a first etching process to form a recess at the bottom of the mask layer extending to both sides of the mask opening includes: performing a first protection step and a first etching step in multiple alternating cycles, wherein the first protection step is used to form a first protection layer covering the surface of the recess, and the first etching step is used to etch the first protection layer and the substrate.

6. The method for forming a semiconductor structure according to claim 5, wherein: The first protection step includes: introducing a first protective gas; The first protective layer is formed on the surface of the recess by using the first protective gas.

7. The method for forming a semiconductor structure according to claim 5, wherein: The first etching step includes: introducing a first etching gas; The first protective layer and the substrate are etched using the first etching gas.

8. The method for forming a semiconductor structure according to claim 2, wherein: The step of patterning the substrate along the notch using a second etching process to form a groove in the substrate includes: performing a second protection step and a second etching step in multiple alternating cycles, wherein the second protection step is used to form a second protection layer covering the surface of the groove, and the second etching step is used to etch the second protection layer and the substrate.

9. The method for forming a semiconductor structure according to claim 8, wherein: The second protection step includes: introducing a second protective gas; The second protective layer is formed on the surface of the groove using the second protective gas.

10. The method for forming a semiconductor structure according to claim 8, wherein: The second etching step includes: introducing a second etching gas; The second protective layer and the substrate are etched using the second etching gas.

11. The method for forming a semiconductor structure according to claim 1, wherein: In the step of providing the substrate, the material of the substrate includes silicon.

12. The method for forming a semiconductor structure according to claim 1, wherein: In the step of providing the substrate, the material of the mask layer includes photoresist or silicon oxide.

13. The method for forming a semiconductor structure according to claim 1, wherein: After patterning the substrate along the notch to form a groove in the substrate, the forming method further includes: removing the mask layer.

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