Diffusion method and system based on photosensitive impurity source and semiconductor device
By coating photosensitive impurity sources onto silicon wafers and using photolithography and development processes, impurity sources can be directly incorporated at high temperatures, solving the problems of complex process steps and high costs in existing technologies, and achieving efficient silicon wafer doping.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG LIOWN SEMICON CO LTD
- Filing Date
- 2026-01-08
- Publication Date
- 2026-05-15
AI Technical Summary
Existing technologies involve complex and costly processes when diffusion of impurity sources onto silicon wafers, and require PECVD equipment and large amounts of etching solution.
A diffusion method based on photosensitive impurity sources is adopted. By coating photosensitive impurity sources on cleaned silicon wafers, patterned areas are formed using photomask exposure and developer, and the photosensitive impurity sources are incorporated into the silicon wafers under high temperature conditions, thus achieving effective doping directly.
It shortens the production cycle, improves doping efficiency, reduces costs, and eliminates the need for growth masks and etching masks.
Smart Images
Figure CN122054925A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically to a diffusion method, system, and semiconductor device based on a photosensitive impurity source. Background Technology
[0002] Currently, the diffusion of impurity sources on silicon wafers requires the deposition of SiO2 / SiN. X The process involves more than five steps, including passivation layer deposition, photolithography, etching, diffusion, and film removal, making it quite complex. Furthermore, the deposition of SiO2 / SiN... X The passivation process also requires PECVD equipment, which increases diffusion costs; in addition, the etching solution consumption is relatively large, further increasing diffusion costs.
[0003] Therefore, how to achieve silicon wafer doping with fewer process steps is an urgent problem to be solved. Summary of the Invention
[0004] The main technical problem solved by this invention is to achieve silicon wafer doping with fewer process steps.
[0005] According to a first aspect, one embodiment provides a diffusion method based on a photosensitive impurity source, the method comprising: The original silicon wafer is cleaned to obtain a cleaned silicon wafer; A photosensitive impurity source is coated onto the cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source. The silicon wafer coated with a photosensitive impurity source is exposed to obtain an exposed silicon wafer; The exposed silicon wafer is developed using a developing solution to form a patterned area containing a photosensitive impurity source on the silicon wafer. After cleaning and drying the silicon wafer, the silicon wafer is placed in an environment with a preset first temperature so that the photosensitive impurity source of the patterned area is incorporated into the silicon wafer, thereby forming an effective doped region.
[0006] According to a second aspect, one embodiment provides a semiconductor device including a multilayer structure, wherein one layer of the multilayer structure is a semiconductor layer, the semiconductor layer being prepared by the diffusion method described above.
[0007] According to a third aspect, one embodiment provides a diffusion system based on a photosensitive impurity source, the diffusion system comprising: Cleaning equipment is used to clean raw silicon wafers to obtain cleaned silicon wafers; Coating equipment is used to coat a photosensitive impurity source onto a cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source; A photolithography device is used to expose the silicon wafer coated with a photosensitive impurity source to obtain the exposed silicon wafer. A developing device uses a developing solution to develop the exposed silicon wafer, thereby forming a patterned area containing a photosensitive impurity source on the silicon wafer; The cleaning equipment is also used to clean the silicon wafers; Drying equipment for drying the silicon wafers; A heating device is used to place the silicon wafer in an environment with a preset first temperature so that the photosensitive impurity source of the patterned area is incorporated into the silicon wafer, thereby forming an effective doped region.
[0008] According to the diffusion method based on photosensitive impurity sources in the above embodiments, after coating a photosensitive impurity source onto a cleaned silicon wafer, the silicon wafer coated with the photosensitive impurity source can be directly exposed using a photomask, and the exposed silicon wafer can be developed using a developer to form a diffusion pattern region containing the photosensitive impurity source. After cleaning and drying the silicon wafer, it is placed in a high-temperature environment so that the photosensitive impurity source in the diffusion region can be directly incorporated into the silicon wafer, thereby forming an effective doped region. This application achieves effective doping by diffusion of photosensitive impurity sources onto silicon wafers mainly through photolithography and diffusion processes. That is, this application can achieve effective doping of silicon wafers with fewer process steps, eliminating the need for growth masks, etching masks, CVD equipment, and etching equipment. The diffusion method of this application not only shortens the production cycle but also improves doping efficiency and reduces doping costs. Attached Figure Description
[0009] Figure 1 This is a schematic flowchart of a diffusion method based on a photosensitive impurity source provided in this embodiment; Figure 2 This embodiment provides a structural block diagram of a diffusion system based on a photosensitive impurity source. Detailed Implementation
[0010] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.
[0011] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.
[0012] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).
[0013] In traditional semiconductor device doping, SiO2 / SiN is used. X The purpose of the passivation layer, combined with photolithography and diffusion, is to achieve regional selective doping (i.e., introducing impurity atoms only in specific regions). The entire process includes 5 core steps: depositing the passivation layer → photolithography → etching → diffusion → film removal. The specific process of each step is as follows: (1) Depositing SiO2 / SiN X A passivation layer is formed by growing a layer of silicon dioxide (SiO2) or silicon nitride (SiN) on the surface of a silicon wafer through chemical vapor deposition (CVD) or thermal oxidation. X (2) Photolithography: First, spin-coat a layer of photoresist (photosensitive material) onto the passivation layer, and then expose it with ultraviolet light through a mask. After exposure, the photoresist dissolves (positive photoresist) or hardens (negative photoresist) in the developer to form a patterned window, exposing the silicon region to be doped. (3) Etching: Use wet etching (such as hydrofluoric acid solution) or dry etching (such as plasma etching) to remove the SiO2 / SiN under the photoresist window. X (4) Diffusion: The silicon wafer is placed in a high-temperature diffusion furnace and impurity gas (such as borane B2H6 or phosphine PH3) is introduced. Impurity atoms diffuse into the exposed silicon lattice through thermal motion to form a PN junction. (5) Film removal: Chemical solvents (such as BOE solution to remove SiO2) or dry etching (to remove SiN) are used. X The remaining passivation layer is completely removed. Finally, the silicon wafer is cleaned (there are also cleaning and drying steps between the above 5 core processes) to prepare for subsequent processes. These 5 steps achieve doping through regional isolation and thermally driven diffusion; however, this doping process involves many steps and is costly.
[0014] Based on this, this application proposes a diffusion method based on photosensitive impurity sources. This diffusion method mainly involves coating a cleaned silicon wafer with a photosensitive impurity source, directly exposing the coated silicon wafer using a photomask, and then developing the exposed silicon wafer with a developer to form a diffusion pattern region containing the photosensitive impurity source. After cleaning and drying the silicon wafer, it is placed in a high-temperature environment so that the photosensitive impurity source in the diffusion pattern region can be directly incorporated into the silicon wafer, thereby forming an effectively doped region. This application achieves effective doping by diffusion of photosensitive impurity sources onto the silicon wafer primarily through photolithography and diffusion processes. That is, this application can achieve effective doping of silicon wafers with fewer process steps, eliminating the need for growth masks, etching masks, CVD equipment, and etching equipment. This diffusion method not only shortens the production cycle but also improves doping efficiency and reduces doping costs. The following detailed description of the photosensitive impurity source-based diffusion method is provided in conjunction with specific embodiments.
[0015] Please refer to Figure 1 , Figure 1 This is a schematic flowchart illustrating a diffusion method based on a photosensitive impurity source provided in this embodiment. Figure 1 As shown, the diffusion method includes steps S101-S105: S101: Clean the original silicon wafer to obtain a cleaned silicon wafer.
[0016] It should be noted that cleaning the raw silicon wafer can be performed using RCA cleaning. Specifically, the raw silicon wafer is rinsed with deionized water or ozone water to remove loose particles from its surface. Then, HPM solution is used to dissolve alkali metal ions and hydroxides of aluminum, iron, and magnesium on the raw silicon wafer. Chloride ions form complexes with the residual metal ions, thus removing metal contamination from the raw silicon wafer. Finally, ultrapure water is used to rinse away chemical residues on the raw silicon wafer, ensuring the cleanliness of the raw silicon wafer surface. In this way, contaminants on the surface of the raw silicon wafer are removed through rinsing, purification, and dissolution processes without damaging the surface properties of the raw silicon wafer.
[0017] It should be noted that the HPM solution can be prepared from hydrochloric acid, hydrogen peroxide, and water in a certain ratio (1:1:6 to 1:2:8). This application does not impose any restrictions on this.
[0018] S102: Coat the cleaned silicon wafer with a photosensitive impurity source to obtain a silicon wafer coated with a photosensitive impurity source.
[0019] It should be noted that the photosensitive impurity source is formed by mixing photoresist with doped impurities, and the photoresist is an organic solvent.
[0020] It should be noted that the photosensitive impurity source is formed by mixing photoresist and liquid impurity source in a ratio of 1:1 to 10:1. For example, the photosensitive impurity source can be formed by mixing photoresist and liquid impurity source in a 1:1 ratio, a 3:1 ratio, an 8:1 ratio, or a 10:1 ratio. This application does not impose any limitations on this. The liquid impurity source includes boron oxide powder and acetone; it may also include boron sources, phosphorus, etc.
[0021] It should be noted that photoresist can be positive photoresist, for example, positive photoresist contains diazonoquinone; of course, photoresist can also be negative photoresist, for example, negative photoresist contains polyisoprene.
[0022] It should be noted that the photosensitive impurity source can be coated onto the cleaned silicon wafer using a solution spin coating method; it can also be coated onto the cleaned silicon wafer using an aerosol spraying method; or it can be directly coated onto the cleaned silicon wafer. This application does not impose any limitations on this method.
[0023] S103: Expose the silicon wafer coated with a photosensitive impurity source to obtain the exposed silicon wafer.
[0024] It should be noted that the photosensitive impurity source can be configured with either positive or negative photoresist. This application does not impose any limitations in this regard.
[0025] It should be noted that the photosensitive impurity source in the positive photoresist configuration includes: diazonoquinone and a liquid impurity source. In practical applications, the impurities in this liquid impurity source diffuse into the silicon wafer and form a PN junction with the impurities on the silicon substrate.
[0026] It should be noted that the photosensitive impurity source in the negative photoresist configuration includes polyisoprene and a liquid impurity source. In practical applications, the impurities in this liquid impurity source diffuse into the silicon wafer and form a PN junction with the impurities on the silicon substrate.
[0027] It should be noted that the exposure process of the silicon wafer coated with photosensitive impurity source can be performed by using a photomask to expose the silicon wafer coated with positive photoresist to obtain the exposed silicon wafer; or by using a photomask to expose the silicon wafer coated with negative photoresist to obtain the exposed silicon wafer.
[0028] In some embodiments, the silicon wafer coated with a photosensitive impurity source is exposed to obtain an exposed silicon wafer, including: A silicon wafer coated with positive photoresist and containing a photosensitive impurity source is exposed using a photomask to obtain a silicon wafer in which the photosensitive impurity source is retained in the shaded area; the shaded area of the photomask is the patterned area. The areas on the silicon wafer that need to be doped can be pre-fabricated using the areas to be doped, i.e., the areas to be doped are the shaded areas of the photomask, and the areas not to be doped are the illuminated areas of the photomask.
[0029] In practical applications, when the photosensitive impurity source is configured with positive photoresist, during the exposure process of the silicon wafer coated with the photosensitive impurity source using a photomask, the positive photoresist (e.g., diazonoquinone) decomposes into carboxylic acids under light and then dissolves in an alkaline developer (e.g., tetramethylammonium hydroxide solution). However, the positive photoresist in the light-shielding area does not decompose or dissolve in the alkaline developer, thus the impurity source in the light-shielding area is preserved. In other words, the exposed silicon wafer retains the pattern area corresponding to the light-shielding area of the photomask.
[0030] In some embodiments, the silicon wafer coated with a photosensitive impurity source is exposed to obtain an exposed silicon wafer, including: A silicon wafer coated with a negative photoresist and containing a photosensitive impurity source is exposed using a photomask to obtain a silicon wafer in which the photosensitive impurity source is retained in the illuminated area; the illuminated area of the photomask is the patterned area. Similarly, which areas on the silicon wafer need to be doped can be pre-fabricated using the areas to be doped, that is, the areas to be doped are the illuminated areas of the photomask, and the areas not to be doped are the shaded areas of the photomask.
[0031] In practical applications, when the photosensitive impurity source is configured with negative photoresist, during the exposure process of the silicon wafer coated with the negative photoresist photosensitive impurity source using a photomask, the negative photoresist (e.g., polyisoprene) undergoes a cross-linking reaction under light, forming a polymer with low solubility. Meanwhile, the photosensitive impurity source in the shaded area dissolves in the neutral developer (e.g., butyl acetate or other organic solvents), thus preserving the impurity source in the illuminated area. In other words, the exposed silicon wafer retains the pattern area corresponding to the illuminated area of the photomask.
[0032] S104: The exposed silicon wafer is developed using a developing solution to form a patterned area containing photosensitive impurity sources on the silicon wafer.
[0033] It should be noted that the developer can be an alkaline developer, such as tetramethylammonium hydroxide solution; or a neutral developer, such as butyl acetate or other organic solvents. This application does not impose any limitations in this regard.
[0034] It should be noted that when the developer is alkaline, the photoresist (e.g., diazonoquinone) in the photosensitive impurity source configured with photoresist will decompose into carboxylic acid under light and dissolve in the alkaline developer (e.g., tetramethylammonium hydroxide solution). However, the photoresist in the light-shielding area will not decompose or dissolve in the alkaline developer. Therefore, the impurity source in the light-shielding area is retained. In other words, the pattern area containing the photosensitive impurity source formed on the silicon wafer at this time corresponds to the light-shielding area.
[0035] It should be noted that when the developer is neutral, the negative photoresist (e.g., polyisoprene) in the photosensitive impurity source configured with negative photoresist undergoes a cross-linking reaction under light, forming a polymer with low solubility. Meanwhile, the photosensitive impurity source in the light-shielding area dissolves in the neutral developer (e.g., butyl acetate or other organic solvents), thus preserving the impurity source in the illuminated area. In other words, the patterned area containing the photosensitive impurity source formed on the silicon wafer corresponds to the illuminated area.
[0036] S105: After cleaning and drying the silicon wafer, place it in an environment at a preset first temperature to allow the photosensitive impurity source in the patterned area to be incorporated into the silicon wafer, thereby forming an effective doped region. In this embodiment, the silicon wafer can be placed in an environment at the preset first temperature for a preset first time to allow the photosensitive impurity source in the patterned area on the silicon wafer to be incorporated into the silicon wafer, thereby becoming an effective doped region.
[0037] It should be noted that placing the silicon wafer in an environment with a preset first temperature can mean placing the silicon wafer in an environment between 900℃ and 1300℃. That is, the preset first temperature is a temperature between 900℃ and 1300℃. For example, the preset first temperature can be 910℃, 980℃, 1000℃, 1110℃, 1200℃, or 1300℃. This application does not impose any limitations on this.
[0038] It should be noted that the preset first duration can be set as needed. For example, the preset first duration can be between 1 hour and 4 hours. This step could involve placing the silicon wafer at a high temperature of 910℃, 980℃, 1000℃, 1110℃, 1200℃, or 1300℃ for 1 hour, 2 hours, 3 hours, or 4 hours. This allows the doped impurities in the photosensitive impurity source within the patterned area on the silicon wafer to diffuse and enter the wafer, thereby forming the effective doped area of the specified pattern. Setting the preset first temperature between 900℃ and 1300℃, and the preset first duration between 1 hour and 4 hours, allows the silicon wafer to achieve doping quickly and stably.
[0039] In some embodiments, after cleaning and drying the silicon wafer and before placing it in an environment with a preset first temperature, the method further includes: The silicon wafer is placed in an environment with a preset second temperature to remove the solvent in the patterned area, leaving doped impurities.
[0040] It should be noted that placing the silicon wafer in an environment at a preset second temperature can mean placing the silicon wafer in an environment at a preset second temperature for a preset second duration. For example, baking the silicon wafer at 150℃-480℃ for 1.5h-3h.
[0041] It should be noted that the preset second temperature is a temperature between 150℃ and 480℃. For example, the preset first temperature can be 160℃, 175℃, 192℃, 230℃, 280℃, 310℃, 370℃, 420℃, or 480℃. This application does not impose any limitations on this.
[0042] It should be noted that the preset second duration can be set as needed, for example, a duration between 1.5h and 3h. Placing the silicon wafer in an environment at the preset second temperature for the preset second duration can involve placing the silicon wafer in an environment of 160℃, 175℃, 192℃, 230℃, 280℃, 310℃, 370℃, 420℃, or 480℃ for 1.5h, 2h, 2.5h, or 3h, allowing the photoresist solvent in the patterned areas on the silicon wafer to completely evaporate, leaving only doped impurities. It should be noted that leaving only doped impurities is to prevent solvent from the photosensitive impurity source from incorporating into the silicon wafer and forming ineffective dopant. Setting the preset second temperature between 150℃ and 480℃ and the preset second duration between 1.5h and 3h allows the solvent to evaporate quickly and completely.
[0043] It should be noted that the effective doping region specifically refers to the area formed by doping impurities into the silicon wafer within the patterned region.
[0044] This embodiment provides a diffusion method based on a photosensitive impurity source. The diffusion method includes: cleaning a raw silicon wafer to obtain a cleaned silicon wafer; coating the cleaned silicon wafer with a photosensitive impurity source to obtain a silicon wafer coated with a photosensitive impurity source; exposing the silicon wafer coated with the photosensitive impurity source to obtain an exposed silicon wafer; developing the exposed silicon wafer with a developing solution to form a patterned region containing the photosensitive impurity source on the silicon wafer; and after cleaning and drying the silicon wafer, placing it in an environment at a preset first temperature to incorporate the photosensitive impurity source from the patterned region into the silicon wafer, thereby forming an effective doped region. By coating the cleaned silicon wafer with a photosensitive impurity source, the silicon wafer coated with the photosensitive impurity source can be directly exposed using a photomask, and the exposed silicon wafer can be developed using a developing solution to form a diffused patterned region containing the photosensitive impurity source. After cleaning and drying the silicon wafer, placing it in a high-temperature environment allows the photosensitive impurity source from the diffused region to be directly incorporated into the silicon wafer, thereby forming an effective doped region. This application achieves effective doping by mainly going through photolithography and diffusion processes when diffusing photosensitive impurity sources on silicon wafers. That is, this application can achieve effective doping of silicon wafers with fewer process steps, without the need for growth masks, etching masks, CVD equipment and etching equipment. The diffusion method of this application not only shortens the production cycle, but also improves doping efficiency and reduces doping cost.
[0045] This application discloses a semiconductor device comprising a multilayer hierarchical structure, wherein one of the hierarchical structures is a semiconductor layer, which is prepared by the diffusion method described above. Specifically, firstly, the original silicon wafer is cleaned to obtain a cleaned silicon wafer; a photosensitive impurity source is coated on the cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source; then, the silicon wafer coated with the photosensitive impurity source is exposed to obtain an exposed silicon wafer; the exposed silicon wafer is developed using a developing solution to form a patterned region containing a photosensitive impurity source on the silicon wafer; finally, after cleaning and drying the silicon wafer, the silicon wafer is placed in an environment with a preset first temperature to allow the photosensitive impurity source in the patterned region to be incorporated into the silicon wafer, thereby forming an effective doped region, and thus obtaining the semiconductor layer. This application involves coating a photosensitive impurity source onto a cleaned silicon wafer, followed by direct exposure of the coated wafer using a photomask, and then developing the exposed wafer with a developer to form a diffusion pattern region containing the photosensitive impurity source. After cleaning and drying the silicon wafer, it is placed in a high-temperature environment to allow the photosensitive impurity source in the diffusion region to be directly incorporated into the silicon wafer, thereby forming an effectively doped region. This application achieves effective doping by diffusion of the photosensitive impurity source onto the silicon wafer primarily through photolithography and diffusion processes. In other words, this application can achieve effective doping of silicon wafers with fewer process steps, eliminating the need for growth masks, etching masks, CVD equipment, and etching equipment. This diffusion method not only shortens the production cycle but also improves doping efficiency and reduces doping costs.
[0046] It should be noted that the semiconductor layer can be a silicon substrate, an epitaxial layer, or a polycrystalline silicon layer, etc.
[0047] Please refer to Figure 2 , Figure 2 A structural block diagram of a diffusion system based on a photosensitive impurity source is provided in this embodiment, as follows: Figure 2 As shown, the diffusion system 20 includes: Cleaning equipment 201 is used to clean raw silicon wafers to obtain cleaned silicon wafers.
[0048] It should be noted that cleaning the raw silicon wafer can be performed using RCA cleaning. Specifically, the raw silicon wafer is rinsed with deionized water or ozone water to remove loose particles from its surface. Then, HPM solution is used to dissolve alkali metal ions and hydroxides of aluminum, iron, and magnesium on the raw silicon wafer. Chloride ions form complexes with the residual metal ions, thus removing metal contamination from the raw silicon wafer. Finally, ultrapure water is used to rinse away chemical residues on the raw silicon wafer, ensuring the cleanliness of the raw silicon wafer surface. In this way, contaminants on the surface of the raw silicon wafer are removed through rinsing, purification, and dissolution processes without damaging the surface properties of the raw silicon wafer.
[0049] The coating equipment 202 is used to coat a photosensitive impurity source onto a cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source.
[0050] It should be noted that the photosensitive impurity source is formed by mixing photoresist with doped impurities, and the photoresist is an organic solvent.
[0051] It should be noted that the photosensitive impurity source is formed by mixing photoresist and liquid impurity source in a ratio of 1:1 to 10:1. For example, the photosensitive impurity source can be formed by mixing photoresist and liquid impurity source in a 1:1 ratio, a 3:1 ratio, an 8:1 ratio, or a 10:1 ratio. This application does not impose any limitations on this. The liquid impurity source includes boron oxide powder and acetone; it may also include boron sources, phosphorus, etc.
[0052] It should be noted that photoresist can be positive photoresist, for example, positive photoresist contains diazonoquinone; of course, photoresist can also be negative photoresist, for example, negative photoresist contains polyisoprene.
[0053] It should be noted that the photosensitive impurity source can be coated onto the cleaned silicon wafer using a solution spin coating method; it can also be coated onto the cleaned silicon wafer using an aerosol spraying method; or it can be directly coated onto the cleaned silicon wafer. This application does not impose any limitations on this method.
[0054] The photolithography equipment 203 exposes a silicon wafer coated with a photosensitive impurity source to obtain the exposed silicon wafer.
[0055] It should be noted that the photosensitive impurity source can be configured with either positive or negative photoresist. This application does not impose any limitations in this regard.
[0056] It should be noted that the photosensitive impurity source in the positive photoresist configuration includes: diazonoquinone and a liquid impurity source. In practical applications, the impurities in this liquid impurity source diffuse into the silicon wafer and form a PN junction with the impurities on the silicon substrate.
[0057] It should be noted that the photosensitive impurity source in the negative photoresist configuration includes polyisoprene and a liquid impurity source. In practical applications, the impurities in this liquid impurity source diffuse into the silicon wafer and form a PN junction with the impurities on the silicon substrate.
[0058] It should be noted that the exposure process of the silicon wafer coated with photosensitive impurity source can be performed by using a photomask to expose the silicon wafer coated with positive photoresist to obtain the exposed silicon wafer; or by using a photomask to expose the silicon wafer coated with negative photoresist to obtain the exposed silicon wafer.
[0059] In practical applications, when the photosensitive impurity source is configured with positive photoresist, during the exposure process of the silicon wafer coated with the photosensitive impurity source using a photomask, the positive photoresist (e.g., diazonoquinone) decomposes into carboxylic acids under light and then dissolves in an alkaline developer (e.g., tetramethylammonium hydroxide solution). However, the positive photoresist in the light-shielding area does not decompose or dissolve in the alkaline developer, thus the impurity source in the light-shielding area is preserved. In other words, the exposed silicon wafer retains the pattern area corresponding to the light-shielding area of the photomask.
[0060] In practical applications, when the photosensitive impurity source is configured with negative photoresist, during the exposure process of the silicon wafer coated with the negative photoresist photosensitive impurity source using a photomask, the negative photoresist (e.g., polyisoprene) undergoes a cross-linking reaction under light, forming a polymer with low solubility. Meanwhile, the photosensitive impurity source in the shaded area dissolves in the neutral developer (e.g., butyl acetate or other organic solvents), thus preserving the impurity source in the illuminated area. In other words, the exposed silicon wafer retains the pattern area corresponding to the illuminated area of the photomask.
[0061] The developing equipment 204 uses a developing solution to develop the exposed silicon wafer, thereby forming a patterned area containing photosensitive impurity sources on the silicon wafer.
[0062] It should be noted that the developer can be an alkaline developer, such as tetramethylammonium hydroxide solution; or a neutral developer, such as butyl acetate or other organic solvents. This application does not impose any limitations in this regard.
[0063] It should be noted that when the developer is alkaline, the photoresist (e.g., diazonoquinone) in the photosensitive impurity source configured with photoresist will decompose into carboxylic acid under light and dissolve in the alkaline developer (e.g., tetramethylammonium hydroxide solution). However, the photoresist in the light-shielding area will not decompose or dissolve in the alkaline developer. Therefore, the impurity source in the light-shielding area is retained. In other words, the pattern area containing the photosensitive impurity source formed on the silicon wafer at this time corresponds to the light-shielding area.
[0064] It should be noted that when the developer is neutral, the negative photoresist (e.g., polyisoprene) in the photosensitive impurity source configured with negative photoresist undergoes a cross-linking reaction under light, forming a polymer with low solubility. Meanwhile, the photosensitive impurity source in the light-shielding area dissolves in the neutral developer (e.g., butyl acetate or other organic solvents), thus preserving the impurity source in the illuminated area. In other words, the patterned area containing the photosensitive impurity source formed on the silicon wafer corresponds to the illuminated area.
[0065] The cleaning equipment 201 is also used for cleaning silicon wafers.
[0066] Drying equipment 205 is used to dry silicon wafers.
[0067] Heating device 206 is used to place the silicon wafer in an environment at a preset first temperature, so that the photosensitive impurity source of the patterned area is incorporated into the silicon wafer, thereby forming an effective doped region. In this embodiment, the silicon wafer can be placed in an environment at the preset first temperature for a preset first time to allow the photosensitive impurity source of the patterned area on the silicon wafer to be incorporated into the silicon wafer, thereby becoming an effective doped region.
[0068] It should be noted that placing the silicon wafer in an environment with a preset first temperature can mean placing the silicon wafer in an environment between 900℃ and 1300℃. That is, the preset first temperature is a temperature between 900℃ and 1300℃. For example, the preset first temperature can be 910℃, 980℃, 1000℃, 1110℃, 1200℃, or 1300℃. This application does not impose any limitations on this.
[0069] It should be noted that the preset first duration can be set as needed. For example, the preset first duration can be between 1 hour and 4 hours. This step could involve placing the silicon wafer at a high temperature of 910℃, 980℃, 1000℃, 1110℃, 1200℃, or 1300℃ for 1 hour, 2 hours, 3 hours, or 4 hours. This allows the doped impurities in the photosensitive impurity source within the patterned area on the silicon wafer to diffuse and enter the wafer, thereby forming the effective doped area of the specified pattern. Setting the preset first temperature between 900℃ and 1300℃, and the preset first duration between 1 hour and 4 hours, allows the silicon wafer to achieve doping quickly and stably.
[0070] This embodiment provides a diffusion system based on a photosensitive impurity source. The diffusion system includes: a cleaning device for cleaning a raw silicon wafer to obtain a cleaned silicon wafer; a coating device for coating a photosensitive impurity source onto the cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source; a photolithography device for exposing the silicon wafer coated with the photosensitive impurity source to obtain an exposed silicon wafer; a developing device for developing the exposed silicon wafer with a developing solution to form a patterned area containing a photosensitive impurity source on the silicon wafer; a cleaning device for further cleaning the silicon wafer; a drying device for drying the silicon wafer; and a heating device for placing the silicon wafer in an environment with a preset first temperature to incorporate the photosensitive impurity source in the patterned area into the silicon wafer, thereby forming an effective doped region. After coating a photosensitive impurity source onto a cleaned silicon wafer, the wafer can be directly exposed using a photomask, and then developed using a developer to form a diffusion pattern region containing the photosensitive impurity source. After cleaning and drying the silicon wafer, it is placed in a high-temperature environment to allow the photosensitive impurity source in the diffusion region to be directly incorporated into the wafer, thus forming an effectively doped region. This application achieves effective doping by diffusion of photosensitive impurity sources onto the silicon wafer primarily through photolithography and diffusion processes. In other words, this application can achieve effective doping of silicon wafers with fewer process steps, eliminating the need for growth masks, etching masks, CVD equipment, and etching equipment. This diffusion method not only shortens the production cycle but also improves doping efficiency and reduces doping costs.
[0071] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.
Claims
1. A diffusion method based on a photosensitive impurity source, characterized in that, The method includes: The original silicon wafer is cleaned to obtain a cleaned silicon wafer; A photosensitive impurity source is coated onto the cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source. The silicon wafer coated with a photosensitive impurity source is exposed to obtain an exposed silicon wafer; The exposed silicon wafer is developed using a developing solution to form a patterned area containing a photosensitive impurity source on the silicon wafer. After cleaning and drying the silicon wafer, the silicon wafer is placed in an environment with a preset first temperature so that the photosensitive impurity source of the patterned area is incorporated into the silicon wafer, thereby forming an effective doped region.
2. The method as described in claim 1, characterized in that, After cleaning and drying the silicon wafer, and before placing the silicon wafer in an environment with a preset first temperature, the method further includes: The silicon wafer is placed in an environment with a preset second temperature to remove the solvent in the patterned area, leaving doped impurities.
3. The method as described in claim 1, characterized in that, The photosensitive impurity source is formed by mixing photoresist with doped impurities, and the photoresist is an organic solvent.
4. The method as described in claim 3, characterized in that, The photosensitive impurity source includes a photosensitive impurity source configured with positive photoresist; The process of exposing the silicon wafer coated with a photosensitive impurity source to obtain the exposed silicon wafer includes: A silicon wafer coated with the positive photoresist and configured as a photosensitive impurity source is exposed using a photomask to obtain a silicon wafer in which the photosensitive impurity source is retained in the light-shielding area; the light-shielding area of the photomask is a patterned area.
5. The method as described in claim 3, characterized in that, The photosensitive impurity source includes a photosensitive impurity source configured with negative photoresist; The process of exposing the silicon wafer coated with a photosensitive impurity source to obtain the exposed silicon wafer includes: A silicon wafer coated with the negative photoresist and configured as a photosensitive impurity source is exposed using a photomask to obtain a silicon wafer in which the photosensitive impurity source is retained in the illuminated area. The illuminated area of the photomask is the graphic area.
6. The method as described in claim 1, characterized in that, The preset first temperature is a temperature between 900℃ and 1300℃.
7. The method as described in claim 2, characterized in that, The preset second temperature is a temperature between 150℃ and 480℃.
8. A semiconductor device, characterized in that, It includes a multi-layered structure, wherein one layer is a semiconductor layer, which is prepared by the diffusion method described in any one of claims 1-7.
9. A diffusion system based on a photosensitive impurity source, characterized in that, The diffusion system includes: Cleaning equipment is used to clean raw silicon wafers to obtain cleaned silicon wafers; Coating equipment is used to coat a photosensitive impurity source onto a cleaned silicon wafer to obtain a silicon wafer coated with a photosensitive impurity source; A photolithography device is used to expose the silicon wafer coated with a photosensitive impurity source to obtain the exposed silicon wafer. A developing device uses a developing solution to develop the exposed silicon wafer, thereby forming a patterned area containing a photosensitive impurity source on the silicon wafer; The cleaning equipment is also used to clean the silicon wafers; Drying equipment for drying the silicon wafers; A heating device is used to place the silicon wafer in an environment with a preset first temperature so that the photosensitive impurity source of the patterned area is incorporated into the silicon wafer, thereby forming an effective doped region.
10. The diffusion system as claimed in claim 9, characterized in that, The preset first temperature is a temperature between 900℃ and 1300℃.