Wafer taking arm for improving front damage in process of depositing oxide film on silicon wafer
By improving the structure and materials of the wafer-picking arm and adopting polyetheretherketone support, the problem of ceramic arm damaging the front of the silicon wafer was solved, the silicon wafer yield was improved and maintenance costs were reduced.
Patent Information
- Application Number
- CN202422458367.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-09-05
- Estimated Expiration
- 2034-10-11
AI Technical Summary
In the existing technology, ceramic wafer picking arms easily cause damage to the front side of silicon wafers when transporting 300mm heavily doped silicon wafers, resulting in the scrapping of silicon wafers, and cannot effectively avoid the autodoping effect and metal contamination.
The detachable support is made of polyetheretherketone material with lower hardness and is designed as 4 support parts on the U-shaped arm body. The support parts are provided with arc-shaped steps, the low-step surface is frosted, and the inclined surface is smooth to reduce the contact area and friction with the silicon wafer.
It significantly reduces the damage to the front side of the silicon wafer, improves the silicon wafer yield, reduces maintenance costs, and ensures the integrity and electrical performance of the silicon wafer.
Smart Images
Figure CN223308977U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of semiconductor production, and in particular relates to a wafer taking arm which can improve the front damage of a silicon wafer during the process of depositing an oxide film. Background Art
[0002] At present, with the vigorous development of the integrated circuit industry, the demand for wafers from IC factories is gradually increasing. As power devices have increasingly higher requirements for low power loss characteristics, in order to meet the requirements of low on-resistance and high breakdown voltage of power devices, low-resistivity heavily doped silicon wafers are needed. In particular, 300mm diameter heavily doped silicon wafers are in short supply. Capacity expansion and yield improvement have become the common goals of major wafer fabs.
[0003] The back-sealing process is one of the core processes in substrate silicon wafer production. This is because the temperature of heavily doped silicon wafers during epitaxial growth is very high (above 1100°C). The dopants in the heavily doped silicon wafers diffuse outward from the heavily doped silicon wafer and mix with the flowing reactants. This phenomenon is generally called the "autodoping effect." When the epitaxial layer grows on the front surface of the silicon wafer, this effect will weaken, but the outward diffusion of the silicon wafer backside will continue. During this high-temperature process, if an oxide film is deposited on the backside of the silicon wafer, it can effectively prevent the outward diffusion of dopants. This layer acts like a sealant to prevent the escape of dopants, avoiding autodoping / metal contamination that affects the electrical properties of the silicon wafer.
[0004] SiO2 thin films grown by atmospheric pressure chemical vapor deposition (APCVD) have become one of the most widely used methods in the back-sealing process due to their high deposition rate, low defect rate and high yield. The APCVD method refers to a method in which one or several gaseous reactants constituting the thin film elements are introduced into a reaction chamber where a substrate is placed under atmospheric pressure, and then a layer of solid thin film is deposited on the surface of the substrate through a gas-phase chemical reaction. The back-sealing process of silicon wafers is as follows: the equipment arm takes out the silicon wafer from the wafer box and sends it into the equipment reaction chamber with the back side facing up. After the film formation is completed, the arm is taken out of the reaction chamber and placed on a cooling table. After cooling, it is transferred to the wafer box. The equipment arm is made of ceramic material to avoid high temperature and metal contamination, but for 300mm silicon wafers, it is a double-sided polished wafer, and the ceramic arm will contact the front of the silicon wafer during transportation. Figures 1 to 4 This is a structural diagram of a typical wafer picking arm used in the prior art. The wafer picking arm is U-shaped as a whole. Four arc-shaped steps 2 integrally formed with the arm body are provided on the U-shaped arm body 1. The silicon wafer 3 is placed on the arc-shaped steps 2. Except for the arc-shaped steps contacting the silicon wafer, the other positions do not contact the silicon wafer. However, it is very easy to cause damage to the front edge of the silicon wafer at the contact position (the hardness of ceramic is greater than that of silicon wafer). The damaged layer cannot be removed during the final polishing process, causing the silicon wafer to be scrapped. Therefore, how to reduce the damage caused by the arm to the front of the silicon wafer has become a problem that needs to be solved urgently. Utility Model Content
[0005] The purpose of the utility model is to solve the deficiencies of the prior art and provide a wafer taking arm which can improve the front damage of the silicon wafer during the process of depositing oxide film.
[0006] The purpose of this utility model is achieved by the following technical solutions:
[0007] A wafer removal arm for improving front-side damage during the deposition of oxide films on silicon wafers, comprising an arm body and a plurality of support members located on the arm body; the support members have a hardness less than that of the silicon wafer to be removed;
[0008] The support member is provided with an arc-shaped step for supporting the silicon wafer.
[0009] Preferably, the arm body is U-shaped;
[0010] The number of the support members is 4, wherein 2 of the support members are symmetrically arranged at the two tail ends of the arm body, and the other 2 support members are symmetrically arranged at the head end of the arm body.
[0011] Preferably, the support member includes a low-level surface, a high-level surface and an inclined surface located between the low-level surface and the high-level surface, the height of the low-level surface is higher than the inner U-shaped arm body, and the low-level surface is used to support the silicon wafer.
[0012] Preferably, the inner circle diameter formed by connecting the low-level surfaces of the plurality of support members is φ1, the outer circle diameter is φ2, and the diameter of the silicon wafer used for support is φ, wherein φ1<φ<φ2.
[0013] Preferably, the U-shaped arm body is provided with a mounting groove for mounting the support member.
[0014] Preferably, the mounting groove is provided with a through hole, the bottom of the support member is provided with a blind hole, and the mounting groove and the support member are connected and fixed by screws passing through the through hole and the blind hole in sequence.
[0015] Preferably, the low-level surface is frosted and has a roughness Ra of 2.5 to 3 μm; and the inclined surface is a smooth surface.
[0016] Preferably, the support member material is polyetheretherketone.
[0017] Preferably, the arc length of the arc-shaped step is 18-20 mm.
[0018] This application improves the damage caused to the front side of the silicon wafer by the wafer-taking arm during the deposition of the oxide film on the back side of the 300mm heavily-doped silicon wafer by optimizing the structure and materials of the silicon wafer transfer arm. In addition, the detachable support design facilitates replacement and reduces the subsequent arm maintenance cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a top view of a typical film-taking arm used in the prior art;
[0020] Figure 2 yes Figure 1 YY-direction cross-sectional view;
[0021] Figure 3 yes Figure 1 The schematic diagram of the structure of the wafer picking arm after carrying the silicon wafer;
[0022] Figure 4 yes Figure 2 The schematic diagram of the structure of the wafer picking arm after carrying the silicon wafer;
[0023] Figure 5 This is a schematic diagram of the top view of the film-taking arm provided in this application;
[0024] Figure 6 yes Figure 5 ZZ-direction cross-section;
[0025] Figure 7 yes Figure 5 The schematic diagram of the structure of the wafer picking arm after carrying the silicon wafer;
[0026] Figure 8 yes Figure 6 The schematic diagram of the structure of the wafer picking arm after carrying the silicon wafer;
[0027] Figure 9 It is the particle situation on the front side of the silicon wafer after being transferred by the wafer picking arm using the existing technology;
[0028] Figure 10 It is the spot condition on the front side of the silicon wafer after being transferred by the wafer picking arm using the existing technology;
[0029] Figure 11 The particle situation on the front side of the silicon wafer after being transferred by the wafer removal arm provided by the present application;
[0030] Among them, 1-arm body; 2-arc-shaped step; 3-silicon wafer; 4-support; 41-low-order surface; 42-inclined surface; 43-high-order surface; 6-mounting slot; 7-screw. DETAILED DESCRIPTION
[0031] The present application provides a wafer removal arm for improving the front damage of the silicon wafer during the deposition of oxide film, such as Figures 5 to 8 As shown, it includes an arm body 1 and multiple support members 4 located on the arm body 1; the hardness of the support members 4 is less than that of the silicon wafer; an arc-shaped step 2 is provided on the support member 4 for supporting the silicon wafer to be taken out.
[0032] In the prior art, the curved step and arm body are integrally formed, and both are made of a relatively hard ceramic material, which can easily damage the silicon wafer when in contact with it. This application utilizes a lower-hardness support member, which is less hard than the silicon wafer, to minimize damage to the wafer. The support member is preferably made of polyetheretherketone (PEEK).
[0033] Moreover, the support member and the arm body are of detachable design, which is convenient for replacement and reduces the subsequent arm maintenance cost. Preferably, a mounting groove 6 is provided on the arm body, and the support member is embedded in the mounting groove and abuts against the arm body on both sides to prevent the support member from separating from the arm body. Furthermore, a through hole is provided on the mounting groove, and a blind hole is provided at the bottom of the support member. The mounting groove 6 and the support member 4 are connected and fixed by screws 7 that pass through the through hole and the blind hole in sequence, which fully ensures the stability of the connection between the support member and the arm body. The blind hole is provided on the support member to ensure that the screw does not pass through the top surface of the support member, thereby avoiding scratching the silicon wafer.
[0034] Preferably, the arm body is U-shaped as a whole; the number of support members 4 is four, of which two support members are symmetrically arranged at the two ends of the U-shaped arm body, and the other two support members are symmetrically arranged at the head end of the U-shaped arm body. In this arrangement, the four support members provide support on all sides of the silicon wafer to prevent the silicon wafer from sliding.
[0035] Preferably, support member 4 includes a low-level surface 41, a high-level surface 43, and an inclined surface 42 located between the low-level surface and the high-level surface. Low-level surface 41 is higher than the inner U-shaped arm body 1. This allows a silicon wafer placed on the low-level surface to avoid contact with the arm body below, minimizing damage to the wafer. The inclined surface increases the space above the low-level surface, making it easier to place the silicon wafer on the low-level surface.
[0036] Furthermore, to increase friction between the curved step and the arm and prevent relative sliding during transfer, the lower step surface is frosted to a roughness Ra of 2.5-3 μm. The inclined surface is not frosted but remains smooth, allowing the wafer to automatically slide down to the lower step surface for support even when placed on the inclined surface.
[0037] The four arc-shaped steps on the arm body in the prior art are relatively long, especially Figure 1 The two curved steps on the right side can support the silicon wafer stably, but the contact area with the silicon wafer is large, which aggravates the damage to the silicon wafer. Preferably, the arc lengths of the four supporting members of the present application are equal, all 18 to 20 mm, which are smaller than the lengths of the four curved steps in the prior art (such as Figure 1The two curved steps on the left are 23-25mm long, while the two on the right are 45-50mm long. This reduces the area of contact with the silicon wafer and minimizes damage. This length also provides stable support for the wafer, especially after the lower surface of the support is frosted, which increases friction with the wafer and provides more stable support.
[0038] Preferably, support member 4 includes a low-level surface 41, a high-level surface 43, and an inclined surface 42 located between the low-level surface and the high-level surface. Low-level surface 41 is higher than the inner U-shaped arm body 1. This allows a silicon wafer placed on the low-level surface to avoid contact with the arm body below, minimizing damage to the wafer. The inclined surface increases the space above the low-level surface, making it easier to place the silicon wafer on the low-level surface.
[0039] Furthermore, the inner diameter of the circle formed by the connected low-step surfaces 41 of the multiple support members 4 is φ1, and the outer diameter is φ2. The diameter of the supported silicon wafer is φ, where φ1 < φ < φ2. This arrangement prevents the silicon wafer from contacting the inclined surfaces on either side when placed on the low-step surface, minimizing damage to the wafer. The width of the low-step surface, (φ2 - φ1) / 2, is 2 mm.
[0040] The double-sided polished heavily doped silicon wafers were transported using the conventional wafer pick-up arm and the wafer pick-up arm provided by the present application for back-side thin film deposition, and then final polishing was performed. After cleaning, the front-side particles and pits of the silicon wafers were measured. The results are as follows: Figures 9-11 As shown, from Figures 9-11 It can be seen that after using the wafer picking arm provided in this application to transport silicon wafers, the number of particles on the surface of the silicon wafer is significantly reduced, and no spots are detected on the front of the silicon wafer after transported by the wafer picking arm provided in this application, which proves that the wafer picking arm provided in this application significantly reduces the damage to the silicon wafer.
[0041] Therefore, this application improves the damage caused to the front side of the silicon wafer by the wafer-taking arm during the deposition of the back oxide film of 300mm heavily-doped silicon wafers by optimizing the structure and materials of the silicon wafer transfer arm. In addition, the detachable support part design facilitates replacement and reduces the subsequent arm maintenance cost.
[0042] As those skilled in the art can understand, in addition to being applied to 300mm heavily doped silicon wafers, the present application can also be applied to other scenarios with similar requirements.
[0043] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Clearly, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, to the extent such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to encompass such changes and modifications.
Claims
1. A wafer taking arm for improving the front surface damage during the deposition of oxide film on silicon wafers, comprising an arm body, characterized in that: It also includes a plurality of support members located on the arm body; the hardness of the support members is less than that of the silicon wafer to be taken; The support member is provided with an arc-shaped step for supporting the silicon wafer.
2. The wafer removal arm for improving front surface damage during silicon wafer oxide film deposition as claimed in claim 1, characterized in that: The arm body is U-shaped; The number of the support members is 4, wherein 2 of the support members are symmetrically arranged at the two tail ends of the arm body, and the other 2 support members are symmetrically arranged at the head end of the arm body.
3. The wafer removal arm for improving front surface damage during silicon wafer oxide film deposition as claimed in claim 1, characterized in that: The support member includes a low-level surface, a high-level surface and an inclined surface located between the low-level surface and the high-level surface. The height of the low-level surface is higher than the inner U-shaped arm body, and the low-level surface is used to support the silicon wafer.
4. The wafer removal arm for improving front surface damage during the deposition of oxide film on silicon wafers according to claim 3, characterized in that: The inner circle diameter formed by connecting the low-level surfaces of the multiple support members is φ1, the outer circle diameter is φ2, and the diameter of the silicon wafer used for support is φ, wherein φ1<φ<φ2.
5. The wafer taking arm for improving front surface damage during the deposition of oxide film on silicon wafers according to claim 2, characterized in that: The arm body is provided with a mounting groove for mounting the support member.
6. The wafer removal arm for improving front surface damage during the deposition of oxide film on silicon wafers according to claim 5, characterized in that: The mounting groove is provided with a through hole, the bottom of the support member is provided with a blind hole, and the mounting groove and the support member are connected and fixed by screws that pass through the through hole and the blind hole in sequence.
7. The wafer removal arm for improving front surface damage during the deposition of oxide film on silicon wafers according to claim 3, characterized in that: The low-level surface is frosted and has a roughness Ra of 2.5 to 3 μm; the inclined surface is a smooth surface.
8. The wafer removal arm for improving front surface damage during silicon wafer oxide film deposition as claimed in claim 1, characterized in that: The support member is made of polyetheretherketone.
9. The wafer removal arm for improving front surface damage during the deposition of oxide film on silicon wafers according to claim 1, characterized in that: The arc length of the arc-shaped step is 18 to 20 mm.