Method of forming a fin

Abstract

A method for forming fins includes: providing a layer to be etched, the layer to be etched having a first sacrificial material layer thereon; forming a first patterning layer on the first sacrificial material layer; forming a plurality of second mask structures according to the first patterning layer; after forming the plurality of second mask structures, forming a plurality of second patterning structures on the first sacrificial material layer; etching the first sacrificial material layer with the plurality of second mask structures and the plurality of second patterning structures as masks to form a plurality of first sacrificial structures and a plurality of second sacrificial structures, the plurality of second sacrificial structures being located between adjacent first sacrificial structures; forming a plurality of first side walls on sidewall surfaces of the plurality of first sacrificial structures and a plurality of second side walls on sidewall surfaces of the plurality of second sacrificial structures; etching the layer to be etched with the plurality of first side walls and the plurality of second side walls as masks to form a substrate, a plurality of first fins, and a plurality of second dummy fins; and removing the plurality of second dummy fins. Thus, the design freedom is high, and the performance and reliability are good.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more particularly to a method for forming a fin. Background Technology

[0002] With the continuous advancement of semiconductor integrated circuit manufacturing technology, performance is constantly improving, accompanied by the miniaturization and micro-miniaturization of devices. In increasingly advanced processes, the goal is to realize as many devices as possible within the smallest possible area.

[0003] In advanced process nodes, fin transistors typically employ self-aligned multiple patterning processes to create fins and gates with smaller and more uniform critical dimensions, thereby reducing device area and improving reliability. There are generally two methods for fin fabrication: one involves forming fins with uniform pitch and then removing excess fins to form the device; the other involves non-uniformly arranged fins while avoiding the generation of excess fins. The former method produces more uniform fin sizes, while the latter method results in more area savings for the device.

[0004] However, existing methods for forming fins still need improvement. Summary of the Invention

[0005] The technical problem solved by this invention is to provide a method for forming fins, so as to form fins with high degree of freedom in non-uniform arrangement design, while improving the performance and reliability of semiconductor structures.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for forming fins, comprising: providing a layer to be etched, the layer to be etched having a first sacrificial material layer; forming a first patterned layer on the first sacrificial material layer; forming a plurality of mutually discrete second mask structures on the first sacrificial material layer according to the first patterned layer; after forming the plurality of second mask structures, forming a plurality of mutually discrete second patterned structures on the first sacrificial material layer, the second patterned structures being located between adjacent second mask structures; etching the first sacrificial material layer using the plurality of second mask structures and the second patterned structures as masks until the surface of the layer to be etched is exposed, forming a plurality of mutually discrete first sacrificial structures and a plurality of mutually discrete second sacrificial structures, the second sacrificial structures being located between adjacent first sacrificial structures; forming a plurality of first sidewalls on the sidewalls of the plurality of first sacrificial structures, and forming a plurality of second sidewalls on the sidewalls of the plurality of second sacrificial structures; etching the layer to be etched using the plurality of first sidewalls and the plurality of second sidewalls as masks to form a substrate, and a plurality of first fins and a plurality of second pseudo-fins located on the substrate and being mutually discrete; and removing the plurality of second pseudo-fins.

[0007] Optionally, the width of the second patterned structure is different from the width of the second mask structure.

[0008] Optionally, the method further includes: forming a second sacrificial material layer on the surface of the first sacrificial material layer before forming the first patterned layer; and forming a plurality of mutually discrete second mask structures on the first sacrificial material layer according to the first patterned layer includes: etching the second sacrificial material layer with the first patterned layer as a mask until the surface of the first sacrificial material layer is exposed to form a plurality of third sacrificial structures; forming a plurality of third sidewalls on the sidewalls of the plurality of third sacrificial structures; and after forming the plurality of third sidewalls, removing the plurality of third sacrificial structures and using the plurality of third sidewalls as the plurality of second mask structures.

[0009] Optionally, the method of forming a plurality of third sidewalls on the sidewall surfaces of a plurality of third sacrificial structures includes: forming a first sidewall material film on the surface of a first sacrificial material layer and on the surfaces of a plurality of third sacrificial structures; and etching the first sidewall material film using an anisotropic etching process until the top surfaces of the plurality of third sacrificial structures and the surface of the first sacrificial material layer are exposed.

[0010] Optionally, it may also include forming a first protective layer on the surface of the first sacrificial material layer before forming the second sacrificial material layer.

[0011] Optionally, the material of the third sacrificial structure includes silicon, the material of the third sidewall includes silicon nitride, and the material of the first protective layer includes silicon oxide.

[0012] Optionally, a method for forming a plurality of first sidewalls on the sidewalls of a plurality of first sacrificial structures and a plurality of second sidewalls on the sidewalls of a plurality of second sacrificial structures includes: forming a second sidewall material film on the surface of the layer to be etched, the surface of the plurality of first sacrificial structures, and the surface of the plurality of second sacrificial structures; and etching the second sidewall material film using an anisotropic etching process until the surface of the layer to be etched, the top surface of the plurality of first sacrificial structures, and the top surface of the plurality of second sacrificial structures are exposed.

[0013] Optionally, the layer to be etched includes: an initial substrate and a second protective layer located on the surface of the initial substrate.

[0014] Optionally, the second protective layer is a stacked composite layer, and the material of the second protective layer includes silicon nitride and silicon oxide.

[0015] Optionally, the method for removing the plurality of second pseudofins includes: forming a third patterned layer on the surface of the substrate, the third patterned layer covering the plurality of first fins and exposing the plurality of second pseudofins; and after forming the third patterned layer, etching the exposed plurality of second pseudofins.

[0016] Optionally, the materials of the first sacrificial material layer, the first sacrificial structure, and the second sacrificial structure include silicon, and the materials of the first sidewall and the second sidewall include silicon nitride.

[0017] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:

[0018] The fin formation method provided by the present invention involves forming a plurality of mutually discrete second mask structures on a first sacrificial material layer based on a first patterning layer; after forming the plurality of second mask structures, forming a plurality of mutually discrete second patterned structures on the first sacrificial material layer, wherein the second patterned structures are located between adjacent second mask structures; etching the first sacrificial material layer using the plurality of second mask structures and the second patterned structures as masks until the surface of the initial substrate is exposed, thereby forming a plurality of mutually discrete first sacrificial structures and a plurality of mutually discrete second sacrificial structures, wherein the second sacrificial structures are located between adjacent first sacrificial structures; forming a plurality of first sidewalls on the sidewalls of the plurality of first sacrificial structures, and forming a plurality of second sidewalls on the sidewalls of the plurality of second sacrificial structures. On one hand, the pattern of the first patterning layer allows for convenient control of the spacing between adjacent first sacrificial structures in a self-aligned multi-patterning process, thus allowing for free definition of the spacing between the first sidewalls located on the sidewalls of different first sacrificial structures. On the other hand, by forming the second patterned structures, a self-aligned dual-patterning process for forming a plurality of second pseudo-fins can be performed without affecting the positional distribution of the first sacrificial structures. Therefore, when etching the initial substrate using several first sidewalls and several second sidewalls as masks to form the substrate, and several first fins and several second pseudo-fins located on the substrate and mutually independent, on the one hand, the positional distribution of the several first fins is less affected by the positional distribution of the several second pseudo-fins, making it easier to form several first fins with a non-uniform distribution that meets design requirements. On the other hand, the uniformity of the mask structure (including several first sidewalls and several second sidewalls) is increased at the non-uniform distribution areas by the several second sidewalls. Therefore, the etching load when forming several first fins is small, and first fins with good morphology can be formed. In summary, it is possible to form several first fins with a high degree of freedom in non-uniform arrangement design while keeping the etching load small and forming first fins with good morphology, thereby improving the performance and reliability of the semiconductor structure. Attached Figure Description

[0019] Figures 1 to 5 This is a cross-sectional structural diagram of the formation steps of a fin;

[0020] Figures 6 to 8 This is a cross-sectional structural diagram of the formation steps of another fin formation method;

[0021] Figures 9 to 18 This is a cross-sectional structural schematic diagram of each step in the fin formation method according to an embodiment of the present invention. Detailed Implementation

[0022] As described in the background section, existing fin formation methods struggle to balance the design freedom of non-uniformity in the fin with the performance and reliability of the semiconductor structure. Specific embodiments will now be analyzed and explained.

[0023] It should be noted that the terms "surface" and "on" in this specification are used to describe the relative spatial relationship and are not limited to whether there is direct contact.

[0024] Figures 1 to 5 This is a cross-sectional structural diagram of the formation steps of a fin.

[0025] Please refer to Figure 1 A substrate 100 is provided, the substrate 100 including a first region I and a second region II, the substrate 100 having a first sacrificial material layer 110 and a second sacrificial material layer (not shown) located on the first sacrificial material layer 110; a photolithographic patterning layer 130 is formed on the second sacrificial material layer.

[0026] Please continue to refer to this. Figure 1 Using the photolithographic patterning layer 130 as a mask, the second sacrificial material layer is etched to form the second sacrificial layer 120.

[0027] Please refer to Figure 2 A second sidewall 121 is formed on the sidewall surface of the second sacrificial layer 120; after the second sidewall 121 is formed, the second sacrificial layer 120 is removed.

[0028] Please refer to Figure 3 Using the second sidewall 121 as a mask, the first sacrificial material layer 110 is etched to form the first sacrificial layer 111.

[0029] Please refer to Figure 4 After forming the first sacrificial layer 111, the second sidewall 121 is removed; after removing the second sidewall 121, a first sidewall 112 is formed on the sidewall surface of the first sacrificial layer 111; after forming the first sidewall 112, the first sacrificial layer 111 is removed; after removing the first sacrificial layer 111, the substrate 100 is etched using the first sidewall 112 as a mask to form a plurality of fins 101.

[0030] Please refer to Figure 5 Remove some fins 101 from the second region II to form a number of fins 101 that are not evenly distributed.

[0031] In this embodiment, since the first sidewall 112 is formed simultaneously on the first region I and the second region II, the mask structure (first sidewall 112) is evenly distributed. As a result, when the substrate 100 is etched to form a plurality of fins 101, the etching load is small and the morphology of the formed fins 101 is good.

[0032] However, since the minimum spacing M1 between the fins 101 on the first region I on both sides of the second region II is determined by the number of fins 101 removed from the second region II, and the patterns of several fins 101 on the first region I and the second region II are all transmitted based on the photolithographic patterning layer 130, the spacing between adjacent fins 101 on the first region I and the second region II is equal. Therefore, the minimum spacing M1 is greatly restricted and the design freedom is low.

[0033] Figures 6 to 8 This is a cross-sectional structural diagram of the formation steps of another fin formation method.

[0034] Please refer to Figure 6 A substrate 200 is provided, wherein a first sacrificial material layer 210 is provided on the substrate 200, and a second sacrificial material layer (not shown) is located on the first sacrificial material layer; a photolithographic patterning layer 230 is formed on the second sacrificial material layer.

[0035] Please continue to refer to this. Figure 6 Using the photolithographic patterning layer 230 as a mask, the second sacrificial material layer is etched to form the second sacrificial layer 220.

[0036] Please refer to Figure 7 A second sidewall 221 is formed on the sidewall of the second sacrificial layer 220; after forming the second sidewall 221, the second sacrificial layer 220 is removed; after removing the second sacrificial layer 220, the first sacrificial material layer 210 is etched using the second sidewall 221 as a mask to form the first sacrificial layer 211.

[0037] Please refer to Figure 8 After forming the first sacrificial layer 211, the second sidewall 221 is removed; after removing the second sidewall 221, a first sidewall 212 is formed on the sidewall surface of the first sacrificial layer 211, and the first sidewall 212 is located on the first region I; after forming the first sidewall 212, the first sacrificial layer 211 is removed; after removing the first sacrificial layer 211, the substrate 200 is etched using the first sidewall 212 as a mask to form a plurality of fins 201 in the first region I.

[0038] compared to Figures 1 to 5 In the illustrated embodiment, a plurality of non-uniformly distributed fins 201 are directly formed by transferring the pattern of the photolithographic patterning layer 230, thereby improving the design freedom of the fins' non-uniformity. However, since the first sidewall 212 is only located on the first region I, when etching the substrate 200 to form the plurality of fins 201, the uniformity of the mask structure (first sidewall 212) is poor, resulting in a severe etching load (e.g., Figure 8 As shown in the second region II), and the morphology of the formed fin 201 is different (as shown in the figure). Figure 8(As shown in region A).

[0039] In summary, existing fin formation methods struggle to balance the design freedom of the fin's non-uniformity with the formation of a fin with low etching load and good morphology. In other words, it is difficult to balance the design freedom of the fin's non-uniformity with the performance and reliability of the semiconductor structure.

[0040] To solve the above-mentioned technical problems, the present invention provides a method for forming fins, comprising: providing a layer to be etched, the layer to be etched having a first sacrificial material layer; forming a first patterned layer on the first sacrificial material layer; forming a plurality of mutually discrete second mask structures on the first sacrificial material layer according to the first patterned layer; after forming the plurality of second mask structures, forming a plurality of mutually discrete second patterned structures on the first sacrificial material layer, the second patterned structures being located between adjacent second mask structures; etching the first sacrificial material layer using the plurality of second mask structures and the second patterned structures as masks until the surface of the layer to be etched is exposed, forming a plurality of mutually discrete first sacrificial structures and a plurality of mutually discrete second sacrificial structures, the second sacrificial structures being located between adjacent first sacrificial structures; forming a plurality of first sidewalls on the sidewalls of the plurality of first sacrificial structures, and forming a plurality of second sidewalls on the sidewalls of the plurality of second sacrificial structures; etching the layer to be etched using the plurality of first sidewalls and the plurality of second sidewalls as masks to form a substrate, and a plurality of first fins and a plurality of second pseudo-fins located on the substrate and being mutually discrete; and removing the plurality of second pseudo-fins. Thus, a balance can be struck between the design freedom of non-uniformity of the fins and the performance and reliability of the semiconductor structure.

[0041] To make the above-mentioned objectives, features and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0042] Figures 9 to 18 This is a cross-sectional structural schematic diagram of each step in the fin formation method according to an embodiment of the present invention.

[0043] Please refer to Figure 9 A layer 300 to be etched is provided, wherein a first sacrificial material layer 400 is provided on the layer 300 to be etched.

[0044] The layer to be etched 300 includes: an initial substrate 310.

[0045] The initial substrate 310 provides material for the subsequent formation of the substrate, a number of first fins, and a number of second pseudofins.

[0046] The material of the initial substrate 310 includes semiconductor materials.

[0047] Specifically, the material of the initial substrate 310 includes silicon.

[0048] In other embodiments, the initial substrate material includes silicon carbide, silicon germanium, a multi-element semiconductor material composed of group III-V elements, silicon-on-insulator (SOI), or germanium-on-insulator (GOI), etc. The multi-element semiconductor material composed of group III-V elements includes InP, GaAs, GaP, InAs, InSb, InGaAs, or InGaAsP, etc.

[0049] In this embodiment, the layer to be etched 300 further includes a second protective layer 320 located on the surface of the initial substrate 310.

[0050] In this embodiment, the second protective layer 320 protects the initial substrate 310 to reduce oxidation of the initial substrate 310. Furthermore, the second protective layer 320 also serves as an etching stop layer for subsequent etching processes during the formation of the first and second sidewalls.

[0051] In this embodiment, the second protective layer 320 is a stacked composite layer, and the material of the second protective layer 320 includes silicon nitride and silicon oxide.

[0052] In other embodiments, the second protective layer is a single-layer structure.

[0053] The first sacrificial material layer 400 is used to form the first sacrificial structure in the future.

[0054] In this embodiment, the material of the first sacrificial material layer 400 includes silicon.

[0055] Please continue to refer to this. Figure 9 A second sacrificial material layer 420 is formed on the surface of the first sacrificial material layer 400.

[0056] The second sacrificial material layer 420 is used to form the third sacrificial structure in the future.

[0057] In this embodiment, the material of the second sacrificial material layer 420 includes silicon.

[0058] Specifically, the process for forming the second sacrificial material layer 420 includes a deposition process, such as a chemical vapor deposition process or a physical vapor deposition process.

[0059] In this embodiment, a first protective layer 410 is formed on the surface of the first sacrificial material layer 400 before the second sacrificial material layer 420 is formed.

[0060] The first protective layer 410 separates the first sacrificial material layer 400 and the second sacrificial material layer 420, serving as an etching stop layer during the subsequent etching of the second sacrificial material layer 420 to form the third sacrificial structure. Furthermore, the first protective layer 410 improves the surface smoothness and interface states of the first sacrificial material layer 400, thereby enhancing the pattern accuracy of the subsequently formed first patterned layer and improving the stability of pattern transfer in the first patterned layer. In addition, the first protective layer 410 reduces the oxidation risk of the first sacrificial material layer 400.

[0061] In this embodiment, the material of the first protective layer 410 includes silicon oxide.

[0062] In this embodiment, the process of forming the first protective layer 410 includes a deposition process, such as a chemical vapor deposition process or a physical vapor deposition process.

[0063] Please continue to refer to this. Figure 9 A first patterned layer 431 is formed on the first sacrificial material layer 400.

[0064] Specifically, in this embodiment, a first patterned layer 431 is formed on the surface of the second sacrificial material layer 420.

[0065] Subsequently, the spacing between adjacent first sacrificial structures is defined through the first patterning layer 431 to form a number of first fins arranged in a non-uniform manner that conforms to the design spacing.

[0066] In this embodiment, the material of the first patterning layer 431 includes photoresist.

[0067] In this embodiment, the process of forming the first patterned layer 431 includes: illumination and development, etc.

[0068] Next, a plurality of mutually discrete second mask structures are formed on the first sacrificial material layer 400 based on the first patterning layer 431. For a detailed description of the formation process of the plurality of mutually discrete second mask structures, please refer to [link to documentation / reference]. Figure 10 and Figure 12 .

[0069] Please refer to Figure 10 Using the first patterned layer 431 as a mask, the second sacrificial material layer 420 is etched until the surface of the first sacrificial material layer 400 is exposed, forming a plurality of third sacrificial structures 421.

[0070] Specifically, in this embodiment, since a first protective layer 410 is formed, the second sacrificial material layer 420 is etched using the first patterned layer 431 as a mask until the surface of the first protective layer 410 is exposed.

[0071] In this embodiment, the material of the third sacrificial structure 421 includes silicon.

[0072] In this embodiment, the etching process of the second sacrificial material layer 420 includes at least one of dry etching and wet etching.

[0073] In this embodiment, after forming several third sacrificial structures 421, the first patterning layer 431 is removed.

[0074] The process for removing the first patterned layer 431 includes ashing processes, etc.

[0075] Please refer to Figure 11 Several third sidewalls 422 are formed on the sidewalls of several third sacrificial structures 421.

[0076] In this embodiment, the material of the third sidewall 422 includes silicon nitride.

[0077] In this embodiment, the method of forming a plurality of third sidewalls 422 on the sidewall surfaces of a plurality of third sacrificial structures 421 includes: forming a first sidewall material film (not shown) on the surface of the first sacrificial material layer 400 and the surfaces of the plurality of third sacrificial structures 421; and etching the first sidewall material film using an anisotropic etching process until the top surfaces of the plurality of third sacrificial structures 421 and the surface of the first sacrificial material layer 400 are exposed.

[0078] In this embodiment, the process for forming the first sidewall material film includes a deposition process, such as a chemical vapor deposition process or a physical vapor deposition process.

[0079] In this embodiment, the anisotropic etching process includes a dry etching process. Specifically, the dry etching process is, for example, a plasma etching process.

[0080] Please refer to Figure 12 After forming several third sidewalls 422, several third sacrificial structures 421 are removed, and the several third sidewalls 422 are used as several second mask structures.

[0081] In this embodiment, the process for removing several third sacrificial structures 421 includes at least one of dry etching and wet etching.

[0082] Please refer to Figure 13 After forming a plurality of second mask structures (third sidewalls 422), a plurality of mutually independent second patterned structures 432 are formed on the first sacrificial material layer 400, the second patterned structures 432 being located between adjacent second mask structures (third sidewalls 422).

[0083] Subsequently, through the graphic transmission of the second graphic structure 432, a number of second pseudofins are formed between adjacent first fins.

[0084] In this embodiment, the material of the second patterned structure 432 includes photoresist.

[0085] In this embodiment, the process of forming the second patterned structure 432 includes: illumination and development, etc.

[0086] In this embodiment, the width of the second patterned structure 432 is different from the width of the second mask structure. Therefore, even with a high degree of freedom in non-uniform design, uniformity can be efficiently improved at non-uniform distribution points (between adjacent second mask structures). Specifically, the width of the second patterned structure 432 can be determined based on the spacing between adjacent second mask structures.

[0087] Please refer to Figure 14 Using several second mask structures (third sidewalls 422) and a second patterned structure 432 as masks, the first sacrificial material layer 400 is etched until the surface of the layer 300 to be etched is exposed, forming several mutually independent first sacrificial structures 401 and several mutually independent second sacrificial structures 402, with the second sacrificial structures 402 located between adjacent first sacrificial structures 401.

[0088] Specifically, the first sacrificial structure 401 is formed based on the second mask structure (third sidewall 422), and the second sacrificial structure 402 is formed based on the second patterned structure 432.

[0089] In this embodiment, the materials of the first sacrificial structure 401 and the second sacrificial structure 402 include silicon.

[0090] In this embodiment, the etching process of the first sacrificial material layer 400 includes at least one of dry etching and wet etching.

[0091] In this embodiment, after forming a plurality of first sacrificial structures 401 and a plurality of second sacrificial structures 402, a plurality of second mask structures (third sidewalls 422) and a second patterned structure 432 are removed.

[0092] Please refer to Figure 15 A plurality of first sidewalls 441 are formed on the sidewalls of a plurality of first sacrificial structures 401, and a plurality of second sidewalls 442 are formed on the sidewalls of a plurality of second sacrificial structures 402.

[0093] The first sidewall 441 is used to define the first fin later, and the second sidewall 442 is used to define the second pseudofin later.

[0094] In this embodiment, the material of the first sidewall 441 and the second sidewall 442 includes silicon nitride.

[0095] In this embodiment, a plurality of first sidewalls 441 are formed on the sidewall surfaces of a plurality of first sacrificial structures 401, and a plurality of second sidewalls 442 are formed on the sidewall surfaces of a plurality of second sacrificial structures 402. The method includes: forming a second sidewall material film (not shown) on the surface of the layer to be etched 300, the surface of the plurality of first sacrificial structures 401, and the surface of the plurality of second sacrificial structures 402; and etching the second sidewall material film using an anisotropic etching process until the surface of the layer to be etched 300, the top surface of the plurality of first sacrificial structures 401, and the top surface of the plurality of second sacrificial structures 402 are exposed.

[0096] In this embodiment, the process for forming the second sidewall material film includes a deposition process, such as a chemical vapor deposition process or a physical vapor deposition process.

[0097] In this embodiment, the etching process for etching the anisotropy of the second sidewall material film includes a dry etching process. Specifically, the dry etching process is, for example, a plasma etching process.

[0098] In this embodiment, after the first sidewall 441 and the second sidewall 442 are formed, the first sacrificial structure 401 and the second sacrificial structure 402 are removed.

[0099] Please refer to Figure 16 Using a number of first sidewalls 441 and a number of second sidewalls 442 as masks, the layer to be etched 300 is etched to form a substrate 311, and a number of first fins 321 and a number of second pseudo fins 322 located on the substrate 311 and being separate from each other.

[0100] Since a plurality of mutually discrete second mask structures (third sidewalls 422) are formed on the first sacrificial material layer 400 according to the first patterning layer 431; after the plurality of second mask structures (third sidewalls 422) are formed, a plurality of mutually discrete second patterned structures 432 are formed on the first sacrificial material layer 400, the second patterned structures 432 being located between adjacent second mask structures (third sidewalls 422); the first sacrificial material layer 400 is etched using the plurality of second mask structures (third sidewalls 422) and the second patterned structures 432 as masks until the surface of the layer 300 to be etched is exposed, a plurality of mutually discrete first sacrificial structures 401 and a plurality of mutually discrete second sacrificial structures 402 are formed, the second sacrificial structures 402 being located between adjacent first sacrificial structures 401; a plurality of first sidewalls 441 are formed on the sidewalls of the plurality of first sacrificial structures 401, and a plurality of second sidewalls 442 are formed on the sidewalls of the plurality of second sacrificial structures 402. Therefore, on the one hand, the pattern of the first patterning layer 431 allows for convenient control of the spacing between adjacent first sacrificial structures 401 in a self-aligned multi-patterning process, enabling the free definition of the spacing between first sidewalls 441 located on different sidewalls of the first sacrificial structures 401. On the other hand, by forming the second patterning structure 432, a self-aligned dual-patterning process for forming a plurality of second pseudofins 322 can be performed without affecting the positional distribution of the first sacrificial structures 401. Therefore, when etching the layer 300 to be etched using a plurality of first sidewalls 441 and a plurality of second sidewalls 442 as masks to form a substrate 311, and a plurality of first fins 321 and a plurality of second pseudo-fins 322 located on the substrate 311 and being mutually independent, on the one hand, the positional distribution of the plurality of first fins 321 is less affected by the positional distribution of the plurality of second pseudo-fins 322, making it easier to form a plurality of first fins 321 with a non-uniform distribution that meets the design requirements; on the other hand, the uniformity of the mask structure (including the plurality of first sidewalls 441 and the plurality of second sidewalls 442) is increased at the non-uniform distribution locations by the plurality of second sidewalls 442. Therefore, the etching load is small when forming the plurality of first fins 421, and a first fin 421 with a good morphology can be formed. In summary, while forming a plurality of first fins 421 with a high degree of freedom in non-uniform design, the etching load is small and a first fin 421 with a good morphology can be formed, thereby improving the performance and reliability of the semiconductor structure.

[0101] In this embodiment, the etching process of the layer 300 to be etched includes at least one of dry etching process and wet etching process.

[0102] In this embodiment, after forming a plurality of first fins 321 and a plurality of second pseudo-fins 322, the first sidewall 441 and the second sidewall 442 are removed.

[0103] Next, remove several second pseudofins 332. For detailed steps on removing several second pseudofins 332, please refer to [link / reference needed]. Figure 17 and Figure 18 .

[0104] Please refer to Figure 17 A third patterned layer 433 is formed on the surface of the substrate 311, the third patterned layer 433 covering a plurality of first fins 421 and exposing a plurality of second pseudo fins 422.

[0105] In this embodiment, the material of the third patterning layer 433 includes photoresist.

[0106] Specifically, the process of forming the third patterned layer 433 includes: illumination, development, etc.

[0107] The function of the third patterning layer 433 is to protect the first fins 421 when etching the second pseudo fins 422 in the future, so as to retain the first fins 421 while removing the second pseudo fins 422.

[0108] Please refer to Figure 18 After the third patterning layer 433 is formed, a plurality of exposed second pseudofins 422 are etched to remove the plurality of second pseudofins 422.

[0109] This results in a non-uniform distribution of several first fins 421.

[0110] In this embodiment, the etching process for exposing the plurality of second pseudofins 422 includes at least one of dry etching and wet etching.

[0111] In this embodiment, after removing several second pseudo-fins 422, the third patterning layer 433 is removed.

[0112] Specifically, the process of removing the third patterned layer 433 includes an ashing process.

[0113] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for forming a fin, characterized in that, include: A layer to be etched is provided, wherein the layer to be etched has a first sacrificial material layer; A first patterned layer is formed on the first sacrificial material layer; Several mutually independent second mask structures are formed on the first sacrificial material layer according to the first patterning layer; After forming a number of second mask structures, a number of mutually independent second patterned structures are formed on the first sacrificial material layer, with the second patterned structures located between adjacent second mask structures; Using a plurality of second mask structures and a second patterned structure as masks, the first sacrificial material layer is etched until the surface of the layer to be etched is exposed, forming a plurality of mutually independent first sacrificial structures and a plurality of mutually independent second sacrificial structures, wherein the second sacrificial structures are located between adjacent first sacrificial structures; a plurality of first sidewalls are formed on the sidewalls of the plurality of first sacrificial structures, and a plurality of second sidewalls are formed on the sidewalls of the plurality of second sacrificial structures. Using a number of first sidewalls and a number of second sidewalls as masks, the layer to be etched is etched to form a substrate, and a number of first fins and a number of second pseudofins located on the substrate and being independent of each other; Remove some of the second pseudofins.

2. The method for forming fins as described in claim 1, characterized in that, The width of the second patterned structure is different from the width of the second mask structure.

3. The method for forming fins as described in claim 1, characterized in that, Also includes: Before forming the first patterned layer, a second sacrificial material layer is formed on the surface of the first sacrificial material layer; Furthermore, the method of forming a plurality of mutually independent second mask structures on the first sacrificial material layer according to the first patterning layer includes: etching the second sacrificial material layer with the first patterning layer as a mask until the surface of the first sacrificial material layer is exposed, thereby forming a plurality of third sacrificial structures; Several third sidewalls are formed on the sidewalls of several third sacrificial structures; after forming several third sidewalls, several third sacrificial structures are removed, and several third sidewalls are used as several second mask structures.

4. The method for forming fins as described in claim 3, characterized in that, A method for forming a plurality of third sidewalls on the sidewall surfaces of a plurality of third sacrificial structures includes: forming a first sidewall material film on the surface of a first sacrificial material layer and on the surfaces of a plurality of third sacrificial structures; and etching the first sidewall material film using an anisotropic etching process until the top surfaces of the plurality of third sacrificial structures and the surface of the first sacrificial material layer are exposed.

5. The method for forming fins as described in claim 3, characterized in that, Also includes: Before forming the second sacrificial material layer, a first protective layer is formed on the surface of the first sacrificial material layer.

6. The method for forming fins as described in claim 5, characterized in that, The material of the third sacrificial structure includes silicon, the material of the third sidewall includes silicon nitride, and the material of the first protective layer includes silicon oxide.

7. The method for forming a fin as described in claim 1, characterized in that, A method for forming a plurality of first sidewalls on the sidewalls of a plurality of first sacrificial structures and a plurality of second sidewalls on the sidewalls of a plurality of second sacrificial structures includes: forming a second sidewall material film on the surface of the layer to be etched, the surface of the plurality of first sacrificial structures, and the surface of the plurality of second sacrificial structures; and etching the second sidewall material film using an anisotropic etching process until the surface of the layer to be etched, the top surface of the plurality of first sacrificial structures, and the top surface of the plurality of second sacrificial structures are exposed.

8. The method for forming a fin as described in claim 1, characterized in that, The layer to be etched includes: an initial substrate and a second protective layer located on the surface of the initial substrate.

9. The method for forming a fin as described in claim 8, characterized in that, The second protective layer is a stacked composite layer, and the materials of the second protective layer include silicon nitride and silicon oxide.

10. The method for forming a fin as described in claim 1, characterized in that, The method for removing several second pseudofins includes: forming a third patterned layer on the surface of the substrate, the third patterned layer covering several first fins and exposing several second pseudofins; and etching the exposed several second pseudofins after forming the third patterned layer.

11. The method for forming a fin as described in claim 1, characterized in that, The materials of the first sacrificial material layer, the first sacrificial structure, and the second sacrificial structure include silicon, and the materials of the first sidewall and the second sidewall include silicon nitride.

Images