Manufacturing method for semiconductor device

Abstract

A manufacturing method for a semiconductor device. The method comprises: forming a first carbon film (103) on a semiconductor substrate to serve as a mask layer; using a silicon-containing photoresist material to form a patterned photoresist layer (104) on the first carbon film (103); etching the first carbon film (103) using the patterned photoresist layer (104) as a mask; and after a corresponding pattern is transferred onto the first carbon film (103), carbonizing the photoresist layer (104), so as to convert the photoresist layer (104) into a second carbon film (105).

Description

Method for manufacturing semiconductor device Technical Field

[0001] The present invention relates to the technical field of semiconductor device manufacturing, and in particular to a method for manufacturing a semiconductor device. Background Art

[0002] Patterning is a common process or technology in the manufacturing process of semiconductor devices. It usually forms a mask layer on the semiconductor substrate and coats a layer of light-sensitive material (such as a photoresist layer) on the mask layer; then a patterned mask is used to expose the semiconductor substrate to radiation for exposure and development, and the pattern on the patterned mask is transferred to the photoresist layer. After that, the mask layer is etched using the photoresist as a mask, and the pattern in the photoresist layer is transferred to the mask layer.

[0003] The above-mentioned patterning process has the following defects:

[0004] 1. Currently, expensive deposition equipment is typically used to deposit one or more composite films, such as single-crystal silicon, amorphous silicon, silicon oxide, silicon nitride, silicon oxynitride, metal, or metal nitride, as mask layers. This results in long deposition times, low production efficiency, and high costs. Furthermore, etching the mask layer using a photoresist mask requires expensive etching equipment, further increasing manufacturing costs.

[0005] 2. High-temperature processes such as high-temperature ion implantation are often used in the manufacturing of some semiconductor devices. On the one hand, when a film layer with photoresist enters these high-temperature processes, it will contaminate the processing equipment. On the other hand, these high-temperature processes will cause the photoresist to deform and change its morphology, which is not conducive to the transfer of the pattern downward.

[0006] 3. The above-mentioned photoresist layer and mask layer need to be removed through different processes, which are complex and costly. Summary of the Invention

[0007] An object of the present invention is to provide a method for manufacturing a semiconductor device, which can simplify the process and reduce costs.

[0008] To achieve the above object, the present invention provides a method for manufacturing a semiconductor device, comprising:

[0009] providing a semiconductor substrate, and forming a first carbon film serving as a mask layer on the semiconductor substrate;

[0010] forming a patterned photoresist layer on the first carbon film using a silicon-containing photoresist material;

[0011] Using the photoresist layer as a mask, etching the first carbon film to pattern the first carbon film;

[0012] carbonizing the photoresist layer to convert the photoresist layer into a second carbon film;

[0013] The semiconductor substrate is processed using the first carbon film and the second carbon film as masks to form a desired pattern in the semiconductor substrate.

[0014] Optionally, the first carbon film is formed by at least one process selected from the group consisting of coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, and epitaxial growth.

[0015] Optionally, the material of the first carbon film includes amorphous carbon.

[0016] Optionally, the photoresist layer is used as a mask and a dry etching process mainly based on oxygen is adopted to etch the first carbon film to pattern the first carbon film.

[0017] Optionally, the photoresist layer is baked to dry out moisture in the photoresist layer, so that the carbon elements in the photoresist layer are deposited on the first carbon film to form the second carbon film.

[0018] Optionally, the baking temperature is 300°C to 1500°C.

[0019] Optionally, the step of processing the semiconductor substrate using the first carbon film and the second carbon film as masks includes: performing ion implantation on the semiconductor substrate using the first carbon film and the second carbon film as masks to form an ion implantation region having a desired pattern in the semiconductor substrate.

[0020] Optionally, the semiconductor substrate is a silicon carbide epitaxial wafer, and the ion implantation region is a well region, a source region or a body contact region of a silicon carbide transistor.

[0021] Optionally, after processing the semiconductor substrate using the first carbon film and the second carbon film as masks, the method further includes: removing the second carbon film and the first carbon film through the same removal process.

[0022] Optionally, after ion implantation is performed on the semiconductor substrate, and before or after the second carbon film and the first carbon film are removed, the method further includes: annealing and activating the ions implanted in the ion implantation region.

[0023] Compared with the prior art, the technical solution of the present invention forms a first carbon film on a semiconductor substrate as a mask layer, and uses a silicon-containing photoresist material to form a patterned photoresist layer on the first carbon film. After etching the first carbon film using the photoresist layer as a mask and transferring the corresponding pattern to the first carbon film, the photoresist layer is carbonized to convert it into a second carbon film. On the one hand, this can avoid the problem of the film layer with photoresist contaminating the processing machine when entering the subsequent high-temperature processing process, and avoid the problem of the morphology of the photoresist changing under the subsequent high-temperature processing process, which is not conducive to the transfer of the pattern to the semiconductor substrate. On the other hand, after completing the subsequent semiconductor processing process, the second carbon film and the first carbon film can be removed by the same removal process, thereby simplifying the process, reducing costs, and avoiding photoresist residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0025] FIG1 is a schematic flow chart of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

[0026] FIG. 2 is a schematic cross-sectional view of a semiconductor device in a method for manufacturing the semiconductor device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, some technical features known in the art are not described to avoid confusion with the present invention. It should be understood that the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. The same reference numerals throughout represent the same elements. It should be understood that when an element is referred to as being "connected to" or "coupled to" another element, it can be directly connected to the other element, or there can be intervening elements. Conversely, when an element is referred to as being "directly connected to" another element, there are no intervening elements. When used herein, the singular forms "a," "an," and "said / the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term "comprising" is used to identify the presence of certain features, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0028] The technical solutions proposed by the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in a very simplified form and are not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0029] Referring to FIG. 1 , an embodiment of the present invention provides a method for manufacturing a semiconductor device, which includes:

[0030] S1, providing a semiconductor substrate, and forming a first carbon film serving as a mask layer on the semiconductor substrate;

[0031] S2, forming a patterned photoresist layer on the first carbon film using a silicon-containing photoresist material;

[0032] S3, using the photoresist layer as a mask, etching the first carbon film to pattern the first carbon film;

[0033] S4, carbonizing the photoresist layer to convert the photoresist layer into a second carbon film;

[0034] S5, using the first carbon film and the second carbon film as masks, processing the semiconductor substrate to form a desired pattern in the semiconductor substrate.

[0035] Please refer to (A) in Figure 2. In step S1, a semiconductor substrate is provided, and a first carbon film 103 serving as a mask layer is formed on the semiconductor substrate by at least one of any suitable processes such as coating, physical vapor deposition (PVD), chemical vapor deposition (CVD), atomic layer deposition (ALD), epitaxial growth, etc.

[0036] Optionally, before forming the first carbon film 103, an oxide layer (not shown) is formed on the surface of the SiC drift layer 102 by any suitable process such as thermal oxidation, atomic layer deposition, or chemical vapor deposition. The oxide layer can serve as a protective layer, an etch stop layer, etc. in subsequent processes.

[0037] The intrinsic material of the provided semiconductor substrate may include, but is not limited to, at least one of any suitable semiconductor material such as silicon (Si), germanium (Ge), silicon carbide (SiC), silicon germanium (SiGe), gallium nitride (GaN), gallium arsenide (GaAs), etc. The semiconductor substrate may be a bulk single crystal material (e.g., bulk silicon), a semiconductor-on-insulator material (e.g., silicon-on-insulator), or an epitaxial wafer (e.g., a silicon carbide film epitaxially grown on a silicon substrate), etc. As an example, the semiconductor substrate is a silicon carbide epitaxial wafer, which may include a substrate 100 (which may be Si or SiC), a SiC buffer layer 101, and a SiC drift layer 102 stacked sequentially from bottom to top. The substrate 100, SiC buffer layer 101, and SiC drift layer 102 may all be n-type, and the doping concentration of n-type impurities in the substrate 100, SiC buffer layer 101, and SiC drift layer 102 decreases in sequence.

[0038] The first carbon film 103 is mainly made of carbon, for example, amorphous carbon. As an example, in step S1 , the first carbon film 103 is formed on the SiC drift layer 102 by magnetron sputtering (ie, a PVD process).

[0039] In step S2, first, referring to FIG. 2 (A), a photoresist containing silicon and carbon elements (i.e., an organic photosensitive material containing silicon and carbon elements, also referred to as a silicon-containing photoresist material) is coated on the first carbon film 103 to form a photoresist layer 104. The photoresist layer 104 can be exposed, developed, and carbonized. The specific material selected can be any suitable silicon-containing photoresist material in the art, and the present invention is not particularly limited thereto.

[0040] In step S2 , then, referring to (B) in FIG. 2 , the photoresist layer 104 is exposed and developed to form a patterned photoresist layer 104 , that is, a pattern required for device manufacturing is formed in the photoresist layer 104 .

[0041] In step S3, please refer to (C) in Figure 2. Using the patterned photoresist layer 104 as a mask, a dry etching process mainly based on oxygen elements (for example, an oxygen plasma etching process) is adopted to etch the first carbon film 103. The etching stops on the surface of the SiC drift layer 102 or on the oxide layer on the surface of the SiC drift layer 102, thereby patterning the first carbon film 103, that is, removing the first carbon film 103 exposed by the patterned photoresist layer 104, thereby transferring the pattern in the photoresist layer 104 to the first carbon film 103.

[0042] In step S4 , referring to (D) in FIG. 2 , the patterned photoresist layer 104 is carbonized by any appropriate process, thereby converting the patterned photoresist layer 104 into a second carbon film 105 .

[0043] As an example, a semiconductor substrate having a patterned first carbon film 103 is placed in a baking furnace and baked at atmospheric pressure or low pressure at a temperature of, for example, 300°C to 1500°C. An oxygen atmosphere is avoided during the carbonization process to prevent oxidation and combustion of the photoresist. The baking atmosphere is an inert gas, such as argon, or nitrogen, which is non-reactive with the photoresist. This allows the organic matter in the photoresist layer 104 to rapidly volatilize and decompose, allowing the product to be quickly drained away and excess water to be dried, leaving a material primarily composed of the element C deposited on the first carbon film 103 to form the second carbon film 105. This process also reduces impurities in the formed second carbon film 105. This process does not cause undesired deformation of the patterns in the various film layers, preserving the patterns intact. Specifically, the pattern in the second carbon film 105 remains consistent with the patterned photoresist layer 104.

[0044] In step S5, referring to (E) in FIG. 2 , the semiconductor substrate is processed (e.g., using a process at a temperature of not less than 500° C.) using the second carbon film 105 and the first carbon film 103 as masks to form the desired pattern on the semiconductor substrate. Because the photoresist layer has been carbonized to form the second carbon film 105, which is heat-resistant and resistant to deformation in high-temperature environments, the pattern and topography of the second carbon film 105 remain unchanged after the semiconductor substrate with the second carbon film 105 and the first carbon film 103 is placed in a high-temperature processing machine. This facilitates the transfer of the desired pattern onto the semiconductor substrate and eliminates the problem of photoresist contamination of the high-temperature processing machine.

[0045] As an example, high-temperature ion implantation (with an implantation temperature of not less than 500° C.) is performed on the SiC drift layer 102 of the semiconductor substrate using the second carbon film 105 and the first carbon film 103 as masks to form an ion implantation region 106 having a desired pattern in the SiC drift layer 102. The ion implantation region has a good morphology, and the high-temperature ion implantation process does not pose the problem of photoresist contamination of the high-temperature processing equipment.

[0046] After step S5, when it is necessary to remove the second carbon film 105 and the first carbon film 103, please refer to (F) in Figure 2. Since the material properties of the second carbon film 105 and the first carbon film 103 are similar (for example, both are mainly composed of carbon elements), the same removal process can be used to remove the second carbon film 105 and the first carbon film 103.

[0047] As an example, a removal method based on oxygen (O) elements (such as a dry stripping process in an oxygen atmosphere or an oxygen plasma etching process, etc.) is used to remove the second carbon film 105 and the first carbon film 103 at the same time. This can simplify the process, reduce costs, and will not produce photoresist residue.

[0048] Optionally, in one embodiment of the present invention, after removing the second carbon film 105 and the first carbon film 103, a carbon film (not shown) can be re-formed as a protective layer, so that the injected ions can be annealed and activated under the protection of the new carbon film. The newly formed carbon film can protect the surface of the semiconductor substrate and prevent it from being damaged by high temperature during the annealing and activation process.

[0049] Optionally, in another embodiment of the present invention, after ion implantation is performed on the semiconductor substrate and before the second carbon film and the first carbon film are removed, the method further includes: annealing and activating the ions implanted in the ion implantation region 106 .

[0050] In order to better illustrate the technical effects of the present invention, the manufacturing of SiC transistors is taken as an example to compare the existing technology and the solution of the present invention.

[0051] 2 , it is usually necessary to perform multiple ion implantations on the SiC drift layer 102 to form ion implantation regions such as a well region (not shown), a source region (not shown), a JTE region (not shown), and a body contact region (not shown) of the SiC transistor.

[0052] First, in the prior art, any ion implantation process used to form ion implantation regions such as the well region, source region, JTE region, and body contact region of a SiC transistor includes the following steps: depositing silicon oxide or silicon nitride on the SiC drift layer 102 as a mask layer, coating the mask layer with photoresist, performing exposure and development, etching the mask layer using the photoresist as a mask, and then directly performing high-temperature ion implantation using the photoresist and the mask layer as masks to form the corresponding ion implantation region. After the ion implantation process is completed, the photoresist is first removed, followed by the mask layer. The deposition cost of the mask layer is high, and the high-temperature ion implantation process can lead to problems such as photoresist contamination of the machine and deformation of the photoresist at high temperatures, which is not conducive to pattern transfer. Furthermore, the photoresist and mask layer need to be removed separately through different removal processes.

[0053] When any ion implantation process in the ion implantation regions such as the well region, source region, JTE region and body contact region for forming the SiC transistor is replaced by the technical solution of the present invention, please refer to FIG2 , which includes the following processes: first, a first carbon film is deposited on the SiC drift layer 102 as a mask layer to replace the deposition of film layers such as silicon nitride in the prior art, thereby shortening the process time and reducing the cost; then, a silicon-containing photoresist material is used to form a patterned photoresist layer 104 on the first carbon film 103, and further a patterned photoresist layer 104 is used as a mask to form a silicon-containing photoresist layer 104 on the first carbon film 103; The first carbon film 103 is etched; then, the photoresist layer 104 is carbonized to form the second carbon film 105. High-temperature ion implantation is then performed using the second carbon film 105 and the first carbon film 103 as masks to form the corresponding ion implantation areas 106. While the deposition cost of the first carbon film 103 is high, the carbonization of the photoresist layer 104 to form the second carbon film 105 first eliminates the problem of photoresist contamination during the high-temperature ion implantation process, which can also prevent deformation of the photoresist at high temperatures and hinder pattern transfer. The second and first carbon films are then removed using the same removal process. This solution is simple, efficient, and cost-effective, making it suitable for large-scale production.

[0054] In summary, the technical solution of the present invention forms a first carbon film as a mask layer on a semiconductor substrate, and uses a silicon-containing photoresist material to form a patterned photoresist layer on the first carbon film. After etching the first carbon film using the patterned photoresist layer as a mask and transferring the corresponding pattern to the first carbon film, the patterned photoresist layer is carbonized to convert it into a second carbon film. This can, on the one hand, avoid the problem of the film layer with photoresist contaminating the processing machine when entering the subsequent high-temperature processing process, and avoid the problem of the morphology of the photoresist changing during the subsequent high-temperature processing process, which is not conducive to the transfer of the pattern to the semiconductor substrate. On the other hand, after the subsequent semiconductor processing is completed, the second carbon film and the first carbon film can be removed through the same removal process, thereby simplifying the process, reducing costs, and avoiding photoresist residue. The technical solution of the present invention can be applied to the manufacture of any suitable semiconductor device.

[0055] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A method for manufacturing a semiconductor device, characterized in that: include: Providing a semiconductor substrate, and forming a first carbon film serving as a mask layer on the semiconductor substrate; forming a patterned photoresist layer on the first carbon film using a silicon-containing photoresist material; Using the photoresist layer as a mask, etching the first carbon film to pattern the first carbon film; Carbonizing the photoresist layer to convert the photoresist layer into a second carbon film; The semiconductor substrate is processed using the first carbon film and the second carbon film as masks to form a desired pattern in the semiconductor substrate.

2. The manufacturing method according to claim 1, characterized in that The first carbon film is formed by at least one process selected from the group consisting of coating, physical vapor deposition, chemical vapor deposition, atomic layer deposition, and epitaxial growth.

3. The manufacturing method according to claim 1, characterized in that: The material of the first carbon film includes amorphous carbon.

4. The manufacturing method according to claim 1, characterized in that: The photoresist layer is used as a mask and a dry etching process mainly based on oxygen is adopted to etch the first carbon film so as to pattern the first carbon film.

5. The manufacturing method according to claim 1, characterized in that: The photoresist layer is baked to dry out the moisture in the photoresist layer, so that the carbon element in the photoresist layer is deposited on the first carbon film to form the second carbon film.

6. The manufacturing method according to claim 5, characterized in that: The baking temperature is 300°C to 1500°C.

7. The manufacturing method according to any one of claims 1 to 6, characterized in that: The step of processing the semiconductor substrate using the first carbon film and the second carbon film as masks includes: using the first carbon film and the second carbon film as masks, performing ion implantation on the semiconductor substrate to form an ion implantation region with a desired pattern in the semiconductor substrate.

8. The manufacturing method according to claim 7, characterized in that: The semiconductor substrate is a silicon carbide epitaxial wafer, and the ion implantation region is a well region, a source region or a body contact region of a silicon carbide transistor.

9. The manufacturing method according to any one of claims 1 to 6 or 8, characterized in that: After processing the semiconductor substrate using the first carbon film and the second carbon film as masks, the method further includes: removing the second carbon film and the first carbon film through the same removal process.

10. The manufacturing method according to claim 7, characterized in that: After ion implantation is performed on the semiconductor substrate and before or after the second carbon film and the first carbon film are removed, the method further includes: annealing and activating the implanted ions in the ion implantation region.

11. The manufacturing method according to claim 1, characterized in that: Carbonizing the photoresist layer to convert it into a second carbon film includes: carbonizing the photoresist layer to volatilize and decompose the organic matter in the photoresist layer, leaving a material mainly composed of carbon elements, so that the photoresist layer as a whole is converted into a second carbon film that can withstand a high temperature of not less than 500°C and is not easily deformed in a high temperature environment.

12. The manufacturing method according to claim 1, characterized in that: The semiconductor substrate is processed by a high temperature processing technology with a temperature not lower than 500°C.

13. The manufacturing method according to claim 9, characterized in that: In an oxygen atmosphere, a dry stripping process or an oxygen plasma etching process is adopted to remove the second carbon film and the first carbon film at the same time.

14. The manufacturing method according to claim 9, characterized in that: After removing the second carbon film and the first carbon film, the method further includes: re-forming a carbon film as a protective layer, so that the implanted ions are annealed and activated under the protection of the new carbon film.

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