Graphical methods and fin structure formation methods
By forming a first sidewall and a second sidewall material layer on the top wall of the barrier layer and the mandrel pattern, and performing ion implantation to improve the etching rate, the contradiction between the perpendicularity of the sidewall to the substrate and the etching requirements of the isolation layer in the prior art is solved, simplifying the process flow, reducing costs and improving efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI INTEGRATED CIRCUIT RESEARCH & DEVELOPMENT CENTER CO LTD
- Filing Date
- 2022-09-22
- Publication Date
- 2026-05-26
AI Technical Summary
In existing patterning technologies, the perpendicularity between the sidewalls and the substrate and the etching requirements of the isolation layer are contradictory, resulting in high difficulty in process debugging and complex and costly existing processes.
By forming a first sidewall and a second sidewall material layer on the top wall of the barrier layer and the mandrel pattern, and performing ion implantation to improve the etching rate, a mask pattern with better morphology is formed, reducing the number of process steps. Silicon carbonitride, silicon carbon oxycarbonate, or silicon carbonitride is selected as the barrier layer to enhance etching resistance.
It reduces the difficulty of process debugging during graphical processing, simplifies the process flow, improves efficiency and reduces costs, and produces mask patterns with better morphology.
Smart Images
Figure CN116403897B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of integrated circuit technology, and in particular to a patterning method and a method for forming fin structures. Background Technology
[0002] As chip size continues to shrink and graphics cycle time decreases, the requirements for graphics technology are becoming increasingly demanding.
[0003] Taking existing patterning techniques as an example, when forming sidewalls through dry etching, the morphology (sidewall) of the resulting sidewalls must be vertical, and the loss of the isolation layer at the bottom of the sidewall must be minimized to avoid a height difference between the isolation layers on both sides of the sidewall. This height difference would cause structural deformation (uniformity, asymmetry) of the pattern when further etching is performed to transfer the pattern to the next layer. However, based on existing anisotropic etching processes, these two requirements are contradictory. That is, the higher the perpendicularity of the sidewall to the substrate after dry etching, the stronger the dry etching relative to the isolation layer at the bottom of the sidewall, resulting in a greater difference in the etching of the isolation layers on both sides of the sidewall. This leads to a larger height difference between the isolation layers on both sides of the sidewall, which in turn brings great difficulties to the process debugging of patterning techniques. Summary of the Invention
[0004] The purpose of this invention is to provide a patterning method and a fin structure forming method, so as to form a mask pattern with better morphology and reduce the difficulty of process debugging during patterning.
[0005] To address the aforementioned technical problems, this invention provides a patterning method, comprising: providing a substrate, wherein a barrier layer and a mandrel pattern are sequentially formed from bottom to top on the substrate; forming a first sidewall material layer, the first sidewall material layer covering the outer wall of the mandrel pattern and the surface of the barrier layer; performing an ion implantation process on the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer; performing an etching process to remove the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer, retaining the first sidewall material layer on the sidewall of the mandrel pattern as the first sidewall, wherein the etching rate of the ion-implanted first sidewall material layer is greater than the etching rate of the un-ion-implanted first sidewall material layer; and removing the mandrel. The process involves: forming a second sidewall material layer that covers the outer wall of the first sidewall and the surface of the barrier layer, wherein the first sidewall material layer and the second sidewall material layer are made of different materials; performing an ion implantation process on the second sidewall material layer on the top wall of the first sidewall and the second sidewall material layer above the barrier layer; performing an etching process to remove the second sidewall material layer on the top wall of the first sidewall and the second sidewall material layer above the barrier layer, retaining the second sidewall material layer on the sidewall of the first sidewall as the second sidewall, wherein the etching rate of the ion-implanted second sidewall material layer is greater than the etching rate of the un-ion-implanted second sidewall material layer; removing the first sidewall and using the second sidewall as a mask pattern to pattern the substrate.
[0006] Optionally, the barrier layer may be made of silicon carbonitride, silicon carbon oxycarbonate, or silicon carbonitride.
[0007] Optionally, when performing an etching process to form the first sidewall, the etching selectivity ratio of the first sidewall material layer to the barrier layer is greater than 50; when performing an etching process to form the second sidewall, the etching selectivity ratio of the second sidewall material layer to the barrier layer is greater than 50.
[0008] Optionally, when removing the mandrel pattern, the etch selectivity ratio between the mandrel pattern and the barrier layer is greater than 50; when removing the first sidewall, the etch selectivity ratio between the first sidewall material layer and the barrier layer is greater than 50.
[0009] Optionally, the material of the first sidewall material layer includes silicon nitride, and the material of the second sidewall material layer includes silicon oxide; or, the material of the first sidewall material layer includes silicon oxide, and the material of the second sidewall material layer includes silicon nitride.
[0010] Optionally, the first sidewall material layer and the second sidewall material layer are formed using an atomic layer deposition process.
[0011] Optionally, the ions used for ion implantation into the first sidewall material layer or the second sidewall material layer include boron ions or carbon ions, and the implantation angle between the ion implantation and the substrate is 89.5° to 90.5°.
[0012] Based on another aspect of the present invention, this embodiment also provides a method for forming a fin structure, comprising: providing a substrate, wherein a fin hard mask layer, a barrier layer, and a mask pattern are sequentially formed from bottom to top on the substrate, the mask pattern being formed using the patterning method described above; etching the barrier layer and the fin hard mask layer on both sides of the mask pattern to expose the surface of the substrate; etching a portion of the substrate thickness to form a fin pattern; forming an isolation dielectric layer, the isolation dielectric layer filling the spaces between the fin patterns and covering the top wall of the mask pattern; removing the mask pattern, the barrier layer, and the fin hard mask layer, and removing a portion of the isolation dielectric layer to expose the fin pattern and make it protrude beyond the isolation dielectric layer at a predetermined height.
[0013] Optionally, the method for removing the mask pattern, the barrier layer, and the fin hard mask layer, and removing a portion of the thickness of the isolation dielectric layer, includes: using the fin hard mask layer as a grinding stop layer, performing a grinding process on the isolation dielectric layer to remove the mask pattern and the barrier layer; removing the fin hard mask layer to expose the fin pattern; and etching back the isolation dielectric layer, wherein the fin pattern protrudes beyond a predetermined height of the isolation dielectric layer.
[0014] Optionally, the material of the fin hard mask layer includes silicon nitride.
[0015] In summary, this invention increases the etching rate of the ion-implanted portion relative to the un-implanted portion by ion implanting the first and second sidewall material layers on the top walls of the barrier layer and mandrel pattern. This helps eliminate the thickness difference between the barrier layers on both sides of the first and second sidewalls, resulting in a mask pattern with better morphology and reducing the difficulty of process debugging during patterning. Furthermore, this invention only requires one mandrel pattern to form the mask pattern, reducing the number of process steps related to the mandrel pattern compared to existing technologies, thus reducing process complexity, improving efficiency, and reducing costs. Additionally, by using silicon carbonitride, silicon carbide, or carbonitride as the barrier layer, the strong etching resistance of the barrier layer relative to the first and second sidewall material layers further prevents thickness differences between the barrier layers on the first and second sidewalls. Attached Figure Description
[0016] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention.
[0017] Figure 1 This is a flowchart of the graphical method provided in the embodiments of this application;
[0018] Figures 2a to 2i This is a schematic diagram of the structure corresponding to the corresponding steps of the graphical method provided in the embodiments of this application;
[0019] Figures 3a to 3d This is a schematic diagram of the structure corresponding to the steps of the fin structure formation method provided in the embodiments of this application.
[0020] Figures 2a to 3d middle:
[0021] 10-Substrate; 11-Fin hard mask layer; 12-Barrier layer; 13-Core pattern;
[0022] 21-First sidewall material layer; 21a-First sidewall material layer after ion implantation; 21b-First sidewall material layer without ion implantation; 22-First sidewall; 23-Second sidewall material layer; 23a-Second sidewall material layer after ion implantation; 23b-Second sidewall material layer without ion implantation; 24-Second sidewall;
[0023] 101 - Fin pattern; 25 - Isolation medium layer. Detailed Implementation
[0024] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.
[0025] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature, unless otherwise expressly indicated.
[0026] Figure 2 is a flowchart of the graphical method provided in an embodiment of this application. As shown in Figure 2, the graphical method provided in this embodiment includes the following steps:
[0027] S01: A substrate is provided, wherein a barrier layer and a mandrel pattern are formed sequentially from bottom to top on the substrate;
[0028] S02: Form a first sidewall material layer, the first sidewall material layer covering the outer wall of the mandrel pattern and the surface of the barrier layer;
[0029] S03: Perform ion implantation on the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer;
[0030] S04: Perform an etching process to remove the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer, retaining the first sidewall material layer on the sidewall of the mandrel pattern as the first sidewall, wherein the etching rate of the first sidewall material layer after ion implantation is greater than the etching rate of the first sidewall material layer without ion implantation.
[0031] S05: Remove the mandrel pattern;
[0032] S06: Form a second sidewall material layer, the second sidewall material layer covering the outer wall of the first sidewall and the surface of the barrier layer, and the first sidewall material layer and the second sidewall material layer are made of different materials;
[0033] S07: Perform ion implantation on the second sidewall material layer on the top wall of the first sidewall and on the second sidewall material layer above the barrier layer;
[0034] S08: Perform an etching process to remove the second sidewall material layer on the top wall of the first sidewall and the second sidewall material layer above the barrier layer, retaining the second sidewall material layer on the sidewall of the first sidewall as the second sidewall, wherein the etching rate of the second sidewall material layer after ion implantation is greater than the etching rate of the second sidewall material layer without ion implantation.
[0035] S09: Remove the first sidewall and use the second sidewall as a mask pattern to pattern the substrate.
[0036] Figures 2a to 2i This is a structural diagram corresponding to the corresponding steps of the graphical method provided in the embodiments of this application. Next, we will combine... Figures 2a to 2i The graphical method described herein will be explained in detail.
[0037] First, please refer to Figure 2a In step S01, a substrate 10 is provided, and a barrier layer 12 and a mandrel pattern 13 are formed sequentially from bottom to top on the surface of the substrate 10.
[0038] The substrate 10 can be any suitable substrate material well known to those skilled in the art, such as at least one of the following: silicon, silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator (S-SiGeOI), silicon-on-insulator (SiGeOI), and germanium-on-insulator (GeOI). In this embodiment, silicon is used as an example of the material of the substrate 10.
[0039] The substrate 10 may also have a patterned film layer (not shown) to form a patterned structure of the corresponding device. In some embodiments, the patterned film layer on the substrate 10 may be a single-crystal silicon layer to form the fins of a fin field-effect transistor device. In other embodiments, the patterned film layer on the substrate 10 may be a polycrystalline silicon layer to form the core of a semiconductor device. In still other embodiments, the patterned film layer on the substrate 10 may also be a metal layer to form a downstream metal interconnect structure.
[0040] The barrier layer 12 covers the substrate 10 and serves as an etch stop layer (etch stop layer) during the patterning process. The barrier layer 12 exhibits strong etch resistance relative to the mandrel pattern and the subsequently formed first and second sidewall material layers, reducing etch loss during the etching process and thus minimizing pattern deviation during pattern transfer, preventing significant deformation of the formed mask pattern. Preferably, the barrier layer 12 is made of one or more of silicon carbonitride, silicon carbide, or silicon carbonitride-oxygenate. These materials provide strong etch resistance relative to the subsequently formed first and second sidewall material layers, which helps avoid thickness differences between the barrier layers on the first and second sidewalls. The thickness of the barrier layer 12 is, for example, 30 to 50 angstroms.
[0041] The mandrel pattern 13 is formed on the barrier layer 12 and includes a plurality of mandrels spaced apart and having a first pitch. The mandrel pattern 13 can be directly formed using a mandrel material layer (not shown) through photolithography and etching processes. The material of the mandrel pattern 13 can be any suitable material for the mandrel, such as amorphous silicon, amorphous carbon, etc. In this embodiment, the material of the mandrel 12 is amorphous silicon.
[0042] In this embodiment, only one mandrel pattern is needed to complete the patterning on the substrate 10, which can reduce the corresponding process steps and pattern loss during the pattern transfer process.
[0043] Next, please refer to Figure 2b Step S02 is executed to form a first sidewall material layer 21, which covers the outer wall of the mandrel pattern 13 and the surface of the barrier layer 12.
[0044] Specifically, the first sidewall material layer 21 can be formed using atomic layer deposition (ALD) to obtain a first sidewall material layer 21 with uniform thickness. The material of the first sidewall material layer 21 is, for example, silicon nitride or silicon oxide, and the thickness of the first sidewall material layer 21 can be, for example, 10 nanometers to 20 nanometers.
[0045] Next, please refer to Figure 2c In step S03, an ion implantation process is performed on the first sidewall material layer 21 on the top wall of the mandrel pattern 13 and the first sidewall material layer 21 above the barrier layer 12.
[0046] Specifically, the direction of the ion implantation process can be perpendicular to or as perpendicular as possible to the substrate 10, so that the ion implantation angle of the first sidewall material layer 21 above the ion implantation barrier layer 12 and on the top wall of the mandrel pattern 13 can be, for example, 89.5° to 90.5°. The ion type, ion implantation energy, and ion implantation dose of the ion implantation process need to be matched with the material and thickness of the first sidewall material layer 21 in order to break the molecular bonds of the ion-implanted first sidewall material layer 21 to change its properties, thereby making the etching rate of the ion-implanted first sidewall material layer 21a (including the first sidewall material layer 21 on the top wall of the mandrel pattern 13 and the first sidewall material layer 21 above the implantation barrier layer 12) greater than that of the unimplanted first sidewall material layer 21b (the first sidewall material layer 21 on the sidewall of the mandrel pattern 13). In this embodiment, the material of the first sidewall material layer 21 is silicon nitride or silicon oxide, and the implanted ions in the ion implantation process include carbon ions or boron ions. The ion implantation energy is, for example, 1 k eV to 30 k eV, and the ion implantation dose is, for example, 1E 13 to 1E15 atom / cm2.
[0047] Next, please refer to Figure 2d In step S04, an etching process is performed to remove the first sidewall material layer 21 on the top wall of the mandrel pattern 13 and the first sidewall material layer 21 above the barrier layer 13, retaining the first sidewall material layer 21 on the sidewall of the mandrel pattern 13 as the first sidewall 22, and exposing the top wall of the mandrel pattern 13, wherein the etching rate of the first sidewall material layer 21a after ion implantation is greater than the etching rate of the first sidewall material layer 21b without ion implantation.
[0048] Specifically, the first sidewall material layer 21 is vertically etched using a dry etching process. Taking advantage of the anisotropic etching of the dry etching process and the difference in etching rates between the ion-implanted first sidewall material layer 21a and the unimplanted first sidewall material layer 21b (both have relatively high etching selectivity), the first sidewall material layer 21 (the ion-implanted first sidewall material layer 21a) on the barrier layer 12 and the top wall of the mandrel pattern 13 is easily removed, and the remaining (retained) first sidewall material layer 21 serves as the first sidewall 22. The first sidewall 22 has a second pitch, which is approximately 0.5 times the first pitch.
[0049] Furthermore, in the above etching process, the etching selectivity ratio of the first sidewall material layer 21a after ion implantation to the first sidewall material layer 21b without ion implantation is greater than 50, which makes the sidewall of the first sidewall 22 more vertical and the top right angle (corner) of the first sidewall 22 more intact. By forming a first sidewall 22 with better morphology, it is beneficial to high-precision pattern transfer.
[0050] Furthermore, in the above etching process, due to the large etching selectivity ratio of the two and the existence of the etching resistance of the barrier layer 12, the etching loss of the barrier layer 12 between the first sidewalls can be further reduced by reducing the etching intensity (reducing the etching time), which is beneficial to the subsequent pattern transfer on the barrier layer 12.
[0051] Next, please refer to Figure 2e Execute step S05 to remove mandrel pattern 13.
[0052] Specifically, the mandrel pattern 13 can be removed using a wet etching process or a dry etching process, exposing the first sidewall 22 and the barrier layer 12.
[0053] Since the material of the barrier layer 12 includes one or more of silicon carbonitride, silicon carbon oxynitride, or silicon carbonitride, it has strong etching resistance. The etching selectivity ratio between the mandrel pattern 13 and the barrier layer 12 is greater than 50, so that the barrier layer 12 under the original mandrel pattern 13 is etched less, thereby making the surfaces of the barrier layers 12 on both sides of the first sidewall 22 flush or basically flush, without obvious height difference.
[0054] It should be noted that, precisely because the blocking layers 12 on both sides of the first sidewall 22 have a relatively uniform and symmetrical structure (without obvious height difference), this embodiment can complete the patterning with only one core pattern.
[0055] Next, please refer to Figure 2fIn step S06, a second sidewall material layer 23 is formed. The second sidewall material layer 23 covers the outer wall of the first sidewall 22 and the surface of the barrier layer 12, and the materials of the first sidewall material layer 23 and the second sidewall material layer 21 are different.
[0056] Specifically, the second sidewall material layer 23 can be formed using atomic layer deposition (ALD) to facilitate the formation of a uniformly thick second sidewall material layer 23, with a thickness of, for example, 10 nanometers to 20 nanometers. In a preferred embodiment, the first sidewall material layer 21 is made of silicon nitride, and the second sidewall material layer 23 is made of silicon oxide; alternatively, the first sidewall material layer 21 is made of silicon oxide, and the second sidewall material layer 23 is made of silicon nitride.
[0057] Because the first sidewall 22 has a better morphology, such as being more vertical and having a more intact right angle at the top, the morphology of the second sidewall material layer 23 covering the first sidewall 22 is also better.
[0058] Next, please refer to Figure 2g and 2h In steps S07 and S08, an ion implantation process is performed on the second sidewall material layer 23 on the top wall of the first sidewall 22 and the second sidewall material layer 23 above the barrier layer 12, and then an etching process is performed to remove the second sidewall material layer 23 on the top wall of the first sidewall 22 and the second sidewall material layer 23 above the barrier layer 13, retaining the second sidewall material layer 23 on the sidewall of the first sidewall 22 as the second sidewall 24, and exposing the first sidewall 22. The etching rate of the second sidewall material layer 23a after ion implantation is greater than the etching rate of the second sidewall material layer 23b without ion implantation.
[0059] Specifically, an ion implantation process is performed on the second sidewall material layer 23 to change the etching rate of the ion-implanted second sidewall material layer 23a relative to the unimplanted second sidewall material layer 23b. The ion implantation process is similar to the aforementioned ion implantation method and will not be described in detail here.
[0060] Due to the significant difference in etching rates between the two layers and the etching resistance of the barrier layer 12, the etching process can achieve an etching selectivity ratio of more than 50 between the second sidewall material layer and the barrier layer, resulting in minimal etching loss to the barrier layer 12 and thus forming a second sidewall 24 with a better morphology. Preferably, when performing the etching process to form the second sidewall 24, the etching selectivity ratio between the second sidewall material layer 23 and the barrier layer 12 is greater than 50.
[0061] Next, please refer to Figure 2i In step S09, the first sidewall 22 is removed, the second sidewall 24 has a third pitch, the third pitch is about 0.25 times the first pitch, and the second sidewall 24 is used as a mask pattern.
[0062] Specifically, for example, the first sidewall 22 can be removed using a wet etching process or a dry etching process to expose the second sidewall 24 and the barrier layer 12. Due to the strong etching resistance of the barrier layer 12, the barrier layer 12 under the original first sidewall 22 is etched less, resulting in the surfaces of the barrier layers 12 on both sides of the second sidewall 24 being flush or substantially flush, without a significant height difference. Preferably, when removing the first sidewall 22, the etching selectivity ratio between the first sidewall 22 and the barrier layer 12 is greater than 50.
[0063] Therefore, patterning can be achieved through a single mandrel, resulting in a mask pattern with a superior morphology. It should be understood that reducing the number of process steps in the patterning process, i.e., fewer pattern transfers, inherently reduces losses during pattern transfer, which is beneficial for forming a mask pattern with a better morphology. Furthermore, it reduces the complexity of the patterning process, thereby improving efficiency and reducing costs.
[0064] On the other hand, this embodiment also provides a method for forming a fin structure, which includes the following steps:
[0065] S01: A substrate is provided, wherein a fin hard mask layer, a barrier layer and a mandrel pattern are formed sequentially from bottom to top on the substrate;
[0066] S02: Form a first sidewall material layer, the first sidewall material layer covering the outer wall of the mandrel pattern and the surface of the barrier layer;
[0067] S03: Perform ion implantation on the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer;
[0068] S04: Perform an etching process to remove the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer, retaining the first sidewall material layer on the sidewall of the mandrel pattern as the first sidewall, wherein the etching rate of the first sidewall material layer after ion implantation is greater than the etching rate of the first sidewall material layer without ion implantation.
[0069] S05: Remove the mandrel pattern;
[0070] S06: Form a second sidewall material layer, the second sidewall material layer covering the outer wall of the first sidewall and the surface of the barrier layer, and the first sidewall material layer and the second sidewall material layer are made of different materials;
[0071] S07: Perform ion implantation on the second sidewall material layer on the top wall of the first sidewall and on the second sidewall material layer above the barrier layer;
[0072] S08: Perform an etching process to remove the second sidewall material layer on the top wall of the first sidewall and the second sidewall material layer above the barrier layer, retaining the second sidewall material layer on the sidewall of the first sidewall as the second sidewall, wherein the etching rate of the second sidewall material layer after ion implantation is greater than the etching rate of the second sidewall material layer without ion implantation.
[0073] S09: Remove the first sidewall and use the second sidewall as a mask pattern;
[0074] S10: Etch the barrier layers and fin hard mask layers on both sides of the mask pattern to expose the surface of the substrate;
[0075] S11: Etch a portion of the substrate thickness to form a fin pattern;
[0076] S12: Remove the mask pattern, blocking layer, and fin hard mask layer, and remove part of the thickness of the isolation medium layer to expose the fin pattern and make it protrude from the isolation medium layer.
[0077] First, please refer to Figure 3a Steps S01 to S09 are performed to provide a substrate 10, which has a fin hard mask layer 11, a barrier layer 12, and a second sidewall 24 (mask pattern) formed by the patterning method described above, which are sequentially covered from bottom to top.
[0078] The method for forming the barrier layer 12 and the second sidewall 24 can be referred to the foregoing and will not be repeated here.
[0079] The fin hard mask layer 11 covers the surface of the substrate 10 and is used to remove the mask pattern (including the barrier layer 12) after a patterned structure is formed in the substrate 10. Taking the removal of the mask pattern by a polishing process as an example, the fin hard mask layer 11 can be a mask stop layer. The fin hard mask layer 11 can be made of any suitable material as a polishing stop layer, such as silicon nitride, and its thickness can be 50 angstroms to 100 angstroms.
[0080] It should be noted that because the material of the barrier layer 12 is relatively hard (with strong etching resistance), the barrier layer 12 is not suitable as a grinding stop layer. If the barrier layer 12 is thick, it will increase the difficulty of the subsequent removal process. If the barrier layer 12 is thin, it will be easy to misposition during grinding when the barrier layer 12 is used as a grinding stop layer.
[0081] Next, please refer to Figure 3b In step S10, using the mask pattern as a mask, the barrier layer 12 and the fin hard mask layer 11 are etched to expose the surface of the substrate 10, and then a portion of the thickness of the substrate 10 is etched to form the fin pattern 101.
[0082] Specifically, the barrier layer 12 and the fin hard mask layer 11 can be sequentially etched using dry etching to expose the surface of the substrate 10. Then, a portion of the substrate 10 is etched using dry etching to form a fin pattern 101 within the substrate 10. The fin pattern 101 retains a portion of the fin hard mask layer 11, the barrier layer 12, and the mask pattern. Preferably, the barrier layer 12 can be etched using a physically bombarded enhanced dry etching method to improve its etching effect. This physical bombardment enhancement can be achieved by increasing the proportion of argon ions in the process gas.
[0083] Next, please refer to Figure 3c Step S11 is executed to form an isolation medium layer 25. The isolation medium layer 25 fills the spaces between the fin patterns 101 and extends over the second sidewall 24 (mask pattern).
[0084] Specifically, the insulating dielectric layer 25 can be formed using the FCVD process to achieve better step coverage and filling. The material of the insulating dielectric layer 25 can be, but is not limited to, silicon oxide.
[0085] Next, please refer to Figure 3d In step S12, the second sidewall 24, the barrier layer 23, and the fin hard mask layer 11 are removed, and a portion of the thickness of the isolation dielectric layer 25 is removed to expose the fin pattern 101 and make it protrude from the isolation dielectric layer 25 at a predetermined height, so that the fin pattern 101 exposed on the isolation dielectric layer 25 can, for example, serve as the fin structure of a fin field-effect transistor device.
[0086] The specific process may include, for example, the following steps: First, using the fin hard mask layer 11 as the grinding stop layer, a grinding process is performed on the isolation dielectric layer 25 to remove the remaining second sidewall 24 and barrier layer 12; then, the fin hard mask layer 11 is removed to expose the fin pattern 101; then, the isolation dielectric layer 25 is etched back so that the fin pattern 101 protrudes from the isolation dielectric layer 25 at a predetermined height.
[0087] In summary, this invention increases the etching rate of the ion-implanted portion relative to the un-implanted portion by ion implanting the first and second sidewall material layers on the top walls of the barrier layer and mandrel pattern. This helps eliminate the thickness difference between the barrier layers on both sides of the first and second sidewalls, resulting in a mask pattern with better morphology and reducing the difficulty of process debugging during patterning. Furthermore, this invention only requires one mandrel pattern to form the mask pattern, reducing the number of process steps related to the mandrel pattern compared to existing technologies, thus reducing process complexity, improving efficiency, and reducing costs. Additionally, by using silicon carbonitride, silicon carbide, or carbonitride as the barrier layer, the strong etching resistance of the barrier layer relative to the first and second sidewall material layers further prevents thickness differences between the barrier layers on the first and second sidewalls.
[0088] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.
Claims
1. A graphical method, characterized in that, include: A substrate is provided, wherein a barrier layer and a mandrel pattern are sequentially formed from bottom to top on the substrate; A first sidewall material layer is formed, which covers the outer wall of the mandrel pattern and the surface of the barrier layer. Ion implantation is performed on the first sidewall material layer on the top wall of the mandrel pattern and on the first sidewall material layer above the barrier layer; An etching process is performed to remove the first sidewall material layer on the top wall of the mandrel pattern and the first sidewall material layer above the barrier layer, while retaining the first sidewall material layer on the sidewall of the mandrel pattern as the first sidewall. The etching rate of the first sidewall material layer after ion implantation is greater than that of the first sidewall material layer without ion implantation. Remove the mandrel pattern; A second sidewall material layer is formed, which covers the outer wall of the first sidewall and the surface of the barrier layer, and the first sidewall material layer and the second sidewall material layer are made of different materials. Ion implantation is performed on the second sidewall material layer on the top wall of the first sidewall and on the second sidewall material layer above the barrier layer; An etching process is performed to remove the second sidewall material layer on the top wall of the first sidewall and the second sidewall material layer above the barrier layer, while retaining the second sidewall material layer on the sidewall of the first sidewall as the second sidewall. The etching rate of the second sidewall material layer after ion implantation is greater than that of the second sidewall material layer without ion implantation. Remove the first sidewall and use the second sidewall as a mask pattern to pattern the substrate.
2. The graphical method according to claim 1, characterized in that, The barrier layer is made of silicon carbonitride, silicon carbon oxynitride, or silicon carbonitride.
3. The graphical method according to claim 1 or 2, characterized in that, When performing an etching process to form the first sidewall, the etch selectivity ratio of the first sidewall material layer to the barrier layer is greater than 50; when performing an etching process to form the second sidewall, the etch selectivity ratio of the second sidewall material layer to the barrier layer is greater than 50.
4. The graphical method according to claim 1 or 2, characterized in that, When removing the mandrel pattern, the etch selectivity ratio between the mandrel pattern and the barrier layer is greater than 50; when removing the first sidewall, the etch selectivity ratio between the first sidewall material layer and the barrier layer is greater than 50.
5. The graphical method according to claim 1 or 2, characterized in that, The material of the first sidewall material layer includes silicon nitride, and the material of the second sidewall material layer includes silicon oxide; or, the material of the first sidewall material layer includes silicon oxide, and the material of the second sidewall material layer includes silicon nitride.
6. The graphical method according to claim 1 or 2, characterized in that, The first sidewall material layer and the second sidewall material layer are formed using atomic layer deposition (ALD) technology.
7. The graphical method according to claim 1 or 2, characterized in that, The ions used for ion implantation into the first sidewall material layer or the second sidewall material layer include boron ions or carbon ions, and the implantation angle between the ion implantation and the substrate is 89.5° to 90.5°.
8. A method for forming a fin structure, characterized in that, include: A substrate is provided, wherein a fin hard mask layer, a barrier layer and a mask pattern are formed sequentially from bottom to top on the substrate, and the mask pattern is formed using the patterning method as described in any one of claims 1 to 7; Etch the barrier layers on both sides of the mask pattern and the fin hard mask layer to expose the surface of the substrate; A portion of the substrate is etched to form a fin pattern; An isolation medium layer is formed, which fills the spaces between the fin patterns and covers the top wall of the mask pattern; Remove the mask pattern, the blocking layer, and the fin hard mask layer, and remove a portion of the thickness of the isolation medium layer to expose the fin pattern and make it protrude beyond the isolation medium layer at a predetermined height.
9. The method for forming the fin structure according to claim 8, characterized in that, The method for removing the mask pattern, barrier layer, and fin hard mask layer, and removing a portion of the thickness of the isolation dielectric layer includes: Using the fin hard mask layer as the grinding stop layer, a grinding process is performed on the isolation medium layer to remove the mask pattern and the barrier layer; Remove the fin hard mask layer to expose the fin pattern; The isolation dielectric layer is etched back to make the fin pattern protrude from the isolation dielectric layer.
10. The method for forming the fin structure according to claim 8 or 9, characterized in that, The material of the fin hard mask layer includes silicon nitride.