A method and apparatus for cleaning the edges of silicon wafers

Abstract

This invention discloses a method and apparatus for cleaning the edges of silicon wafers. The cleaning method includes: cleaning the surface of the silicon wafer using a cleaning unit; after cleaning, using a detection unit to detect contaminants on the edge portion of the silicon wafer surface, identifying areas with excessive contaminants requiring further cleaning, and acquiring the location information of these areas; a control unit controlling the cleaning unit to clean the silicon wafer again based on the location information; and after the second cleaning, the detection unit detecting contaminants on the silicon wafer surface to confirm that there are no areas with excessive contaminants requiring further cleaning on the edge portion of the silicon wafer surface. By specifically cleaning the edges of the silicon wafer surface, it ensures that every location on the edge of the silicon wafer meets the required level of cleanliness.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer cleaning, and more particularly to a method and apparatus for cleaning the edges of silicon wafers. Background Technology

[0002] Before epitaxial growth, silicon wafers often have residual process liquids on their surface due to previous processes. Additionally, particles and metal elements may adsorb onto the wafer surface. These residual process liquids can contaminate and corrode the wafer, potentially causing scratches. The adsorbed particles and metal elements also contribute to surface contamination, negatively impacting subsequent processing and use. Therefore, silicon wafers typically require cleaning before epitaxial growth to remove residual process liquids and adsorbed particles and metal elements.

[0003] In the current silicon wafer processing field, insufficient cleaning capabilities leading to excessive levels of metal particle contaminants, especially bulk iron (Fe), have been a major challenge in epitaxial silicon wafer production. Due to the influence of previous processes, silicon wafers used for epitaxial growth typically have more contamination points in the edge areas. Existing cleaning equipment generally improves the edge cleaning effect by increasing the edge cleaning time, but this method is wasteful and still carries the risk of incomplete cleaning of edge areas. Summary of the Invention

[0004] To address the aforementioned technical problems, embodiments of the present invention aim to provide a cleaning method and apparatus for silicon wafer edges, which ensures that every part of the silicon wafer edge is cleaned by specifically cleaning the edge portion of the silicon wafer surface.

[0005] The technical solution of this invention is implemented as follows:

[0006] In a first aspect, the present invention provides a cleaning method for the edge of a silicon wafer, the cleaning method comprising the following steps: cleaning the surface of the silicon wafer using a cleaning unit; after cleaning, using a detection unit to detect contaminants on the edge portion of the silicon wafer surface, identifying re-cleaning areas with excessive contaminants on the edge portion of the silicon wafer surface, and obtaining the location information of the re-cleaning areas; a control unit controlling the cleaning unit to clean the silicon wafer again based on the location information; after the re-cleaning is completed, the detection unit detecting contaminants on the surface of the silicon wafer, confirming that there are no re-cleaning areas with excessive contaminants on the edge portion of the silicon wafer surface.

[0007] Secondly, the present invention also provides a cleaning apparatus for the edge of a silicon wafer, the apparatus being used to perform the above-described cleaning method, the cleaning apparatus comprising: a cleaning unit for cleaning the surface of the silicon wafer; a detection unit for detecting contaminants on the edge portion of the silicon wafer surface, identifying re-cleaning areas in the edge portion of the silicon wafer surface where contaminants exceed the standard, and acquiring the location information of the re-cleaning areas; a control unit configured to control the cleaning unit to clean the silicon wafer based on the location information; and a driving unit for driving the cleaning unit to move.

[0008] This invention provides a method and apparatus for cleaning the edges of silicon wafers. After completing a cleaning operation, a metal particle distribution map of the edge portion of the silicon wafer surface is obtained by using an optical microscope. The area of ​​the silicon wafer edge that needs to be cleaned more thoroughly is screened out, and the area is converted into position information. The second pipeline in the cleaning unit used for cleaning the edges is then driven to move to the area for targeted cleaning. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a cleaning device in the prior art;

[0010] Figure 2 A map showing the distribution of bulk iron on a silicon wafer surface cleaned using existing cleaning equipment;

[0011] Figure 3 This is a schematic diagram of a cleaning device for the edge of a silicon wafer according to an embodiment of the present invention;

[0012] Figure 4 This is a top view of a cleaning apparatus for the edge of a silicon wafer according to an embodiment of the present invention;

[0013] Figure 5 This is a schematic diagram of the structure of the second pipeline of a cleaning device for the edge of a silicon wafer according to an embodiment of the present invention;

[0014] Figure 6 This is a flowchart of a cleaning method for the edge of a silicon wafer according to an embodiment of the present invention. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0016] For the pre-cleaning of 300mm silicon wafers before heat treatment, the chemical materials used to clean the wafer surface typically include ozone water (O3 water), diluted hydrofluoric acid (HF), and deionized water (DIW), etc.

[0017] To prevent contamination from airborne or chemical particles during the cleaning process, continuous cleaning is generally required. See the appendix for existing technologies. Figure 1 It shows a schematic diagram of a prior art cleaning device that employs a design with a fixed central conduit and fixed edge conduits for cleaning.

[0018] Cleaning silicon wafers with this device can lead to incomplete cleaning of the wafer edges, especially after thermal annealing. This can also cause issues when performing metal particle inspection on the wafers, such as Fe Bulk inspection. (See Appendix) Figure 2 Defects at the edges of silicon wafers are particularly noticeable and fail to meet customer requirements. To improve the cleaning of silicon wafer edges, existing technologies achieve cleaning of different edge locations by rotating the central axis connecting the central and edge conduits. Here, rotating the central axis connecting the central and edge conduits refers to...

[0019] The key is that by rotating the central axis by a certain angle, the trajectories of the central and edge pipelines on the silicon wafer surface become a 5-segment arc. While rotating the central axis increases the cleaning coverage of the central and edge pipelines...

[0020] While it can increase the area, it can also disrupt the cleaning process, leaving the product at risk of contamination during the cleaning process.

[0021] In view of this, see Appendix Figure 3 This invention discloses a cleaning device 10 for the edge of a silicon wafer. The cleaning device is designed for pre-cleaning of 300mm silicon wafers before heat treatment. The cleaning device includes a cleaning unit 1, a detection unit 2, a control unit (not shown), and a drive unit 3. After cleaning the silicon wafer once, the detection unit 2 detects the distribution of contaminants on the surface of the silicon wafer and identifies them.

[0022] The control unit identifies the re-cleaning area with excessive contaminant content on the edge of the silicon wafer surface and obtains the location information of the re-cleaning area. Based on the location information, the control unit drives the cleaning unit 1 through the driving unit 3 to specifically clean the re-cleaning area, thereby improving the technical problem of inadequate cleaning on the edge of the silicon wafer.

[0023] 5. See Appendix Figure 3The cleaning unit 1 includes a first conduit 11 that sprays cleaning fluid to the center of the silicon wafer and a second conduit 12 that sprays cleaning fluid to the edge of the silicon wafer. The first conduit 11 and the second conduit 12 are configured to spray cleaning fluid onto the silicon wafer surface perpendicular to the wafer surface. Both the first conduit 11 and the second conduit 12 are positioned above the front side of the silicon wafer to spray cleaning fluid onto the front side. In another embodiment of the invention, both the first conduit 11 and the second conduit 12 include multiple nozzles. These multiple nozzles are configured to spray different cleaning fluids onto the silicon wafer surface, and are configured to spray simultaneously or alternately. See Appendix Figure 3 As can be seen, the outlets of the first pipe 11 and the second pipe 12 are both located at the ports of the first pipe 11 and the second pipe 12.

[0024] See appendix Figure 3 and attached Figure 5 The driving unit 3 includes a rotating shaft 31 and a translation driver 32. Both the first conduit 11 and the second conduit 12 are mounted on the rotating shaft 31. The rotating shaft 31 drives the first conduit 11 and the second conduit 12 to rotate in a plane parallel to the silicon wafer surface. The rotating shaft 31 is configured to drive the first conduit 11 to rotate from an initial position to the center of the silicon wafer, and also to drive the second conduit 12 to rotate from the treatment position to the edge of the silicon wafer. Here, the initial position refers to a position outside the surface area of ​​the silicon wafer before the first conduit 11 and the second conduit 12 begin cleaning the silicon wafer. See Appendix. Figure 4 It shows a schematic diagram of the first pipe 11 and the second pipe 12 in their initial positions, see Appendix Figure 3 The diagram schematically illustrates the first conduit 11 and the second conduit 12 located at the center and edge positions, respectively. Schematically, the first conduit 11 can rotate 90° from its initial position to the center position of the silicon wafer by being driven by the rotating shaft 31, and the second conduit 12 can rotate 90° from its initial position to the edge position of the silicon wafer by being driven by the rotating shaft 31.

[0025] See appendix Figure 5The second conduit 12 includes a rotating part 121 and an extension part 122. The second conduit 12 is fixedly connected to the rotating shaft 31 through the rotating part 121. The rotating part 121 is perpendicular to the rotating shaft 31 and can move together with the rotation of the rotating shaft 31. The extension part 122 is fitted onto the outer wall of the rotating part 121 and can move along the length of the rotating part 121. The extension part 122 and the rotating part 121 form a telescopic rod structure. Through the telescopic rod structure and the rotating shaft 31, the second conduit 12 can drive the port to move to any position on the edge of the silicon wafer to clean the edge of the silicon wafer. The translation driver 32 in the driving unit 3 serves as the power source for the extension part 122 on the rotating part 121. The translation driver 32 can be a lead screw. See Appendix. Figure 3 and attached Figure 5 The lead screw is fixedly mounted on the rotating shaft 31, perpendicular to the rotating shaft 31, and can move with the rotation of the rotating shaft 31. That is, the lead screw and the rotating part 121 remain stationary relative to each other. The extension part 122 is fixedly connected to the lead screw so that the lead screw can drive the extension part 122 to move along the length direction of the rotating part 121. In another embodiment of the present invention, after the rotating shaft 31 drives the rotating part 121 to rotate to the edge position, the rotating shaft 31 stops driving. Then, the extension part 122 is driven to move along the length direction of the rotating part 121 only by the translation driver 32. At this time, the extension part 122 can perform radial linear reciprocating motion under the drive of the translation driver 32. Through the radial linear reciprocating motion of the extension part 122 and the rotational motion of the silicon wafer around its own axis, the edge portion of the silicon wafer can be thoroughly cleaned at any position through the second pipe 12.

[0026] The detection unit 2 is used to detect contaminants on the surface of the silicon wafer, identify areas on the silicon wafer surface where contaminants exceed the standard for re-cleaning, and obtain the location information of the re-cleaning areas. The detection unit 2 can be composed of an optical microscope, which is positioned above the front surface of the silicon wafer. Schematic, the optical microscope is mounted on the rotation axis 31 and aligned with the upper surface of the silicon wafer, or, as shown in the attached diagram... Figure 3The device is positioned on the first conduit 11 to obtain a metal particle distribution map on the silicon wafer surface via optical scanning. It is important to note that when the detection unit 2 is positioned on either the first conduit 11 or the second conduit 12, during optical scanning of the silicon wafer, the first conduit 11 or the second conduit 12 does not return to its initial position after cleaning but remains directly above the silicon wafer, allowing the detection unit 2 to inspect the surface of the silicon wafer from directly above. The detection unit 2 limits the amount of metal particles on the silicon wafer surface based on the epitaxial process, and uses the metal particle distribution map to identify areas on the silicon wafer surface with excessive metal particle content requiring further cleaning. The detection unit 2 calibrates these areas to obtain their location information and sends this information to the control unit. The control unit, based on this location information, drives the second conduit 12 of the cleaning unit 1 to move to the area requiring further cleaning via the drive unit 3, and then performs enhanced cleaning on the area using the second conduit 12. For example, when the control unit obtains the position information, the control unit sends a control signal to the drive unit 3. The drive unit 3 first drives the rotating shaft 31 to rotate according to the control signal. The rotation of the rotating shaft 31 drives the rotating part 121 of the second pipeline 12 to move simultaneously until the rotating part 121 is aligned with the re-cleaning area. Here, the rotating part 121 being aligned with the re-cleaning area means that the extension line of the rotating part 121 along the length direction passes through the re-cleaning area. After the rotating part 121 is aligned with the re-cleaning area, the drive unit 3 drives the translation driver 32 to move according to the control signal. The translation driver 32 drives the extension part 122 to move on the rotating part 121. Since the rotating part 121 is aligned with the re-cleaning area, the extension part 122 can move the port of the second pipeline 12 above the re-cleaning area under the drive of the translation driver 32, and perform enhanced rinsing of the re-cleaning area through the port.

[0027] Based on the cleaning device for silicon wafer edges disclosed in the above embodiments of the present invention, see attached drawing. Figure 6 The document illustrates a flowchart of a cleaning method for the edge of a silicon wafer according to an embodiment of the present invention. The cleaning method includes the following steps:

[0028] S101. The surface of the silicon wafer is cleaned by cleaning unit 1;

[0029] S102. After cleaning, the detection unit 2 is used to detect contaminants on the surface of the silicon wafer, identify the areas on the silicon wafer surface where the contaminants exceed the standard, and obtain the location information of the areas to be cleaned.

[0030] S103. The control unit controls the cleaning unit 1 to clean the silicon wafer again based on the location information;

[0031] S104. After the second cleaning is completed, the detection unit 2 performs contaminant detection on the surface of the silicon wafer until there are no contaminants exceeding the standard in the re-cleaned area on the surface of the silicon wafer.

[0032] When cleaning the silicon wafer surface through the cleaning unit 1, the driving unit 3 drives the first conduit 11 of the cleaning unit 1 to move from the initial position to the center position of the silicon wafer. Under the drive of the rotating shaft 31, the first conduit 11 moves from the initial position to the center position of the silicon wafer. The driving unit 3 drives the second conduit 12 of the cleaning unit 1 to move from the initial position to the edge position of the silicon wafer. Similarly, under the drive of the rotating shaft 31, the second conduit 12 moves from the treatment position to the edge position of the silicon wafer. The silicon wafer is held by the support platform, and the silicon wafer rotates around its own central axis as the support platform rotates. The first conduit 11 and the second conduit 12 simultaneously spray cleaning fluid onto the silicon wafer to begin cleaning. After cleaning for a fixed time, the first conduit 11 and the second conduit 12 stop spraying cleaning fluid. When cleaning is completed, the first conduit 11 and the second conduit 12 return to the initial position under the drive of the rotating shaft 31.

[0033] After a cleaning process is completed, the detection unit 2 starts working. The optical microscope in the detection unit 2 is aimed at the upper surface of the silicon wafer and obtains the metal particle distribution map of the silicon wafer through optical scanning. In the metal particle distribution map, the content of metal particles per unit area on the surface of the silicon wafer can be obtained. By setting a standard value, the re-cleaning area with excessive metal particle content on the surface of the silicon wafer can be identified. After the detection unit 2 filters out the re-cleaning area, it obtains the location information of the re-cleaning area and transmits the location information to the control unit.

[0034] When the detection unit 2 detects the re-cleaning area, the control unit needs to control the cleaning unit 1 to perform enhanced cleaning on the edge of the silicon wafer based on the position information. After receiving the position information, the control unit sends a control signal to the drive unit 3. The drive unit 3 drives the second pipeline 12 from the initial position to the re-cleaning area to clean the re-cleaning area based on the control signal. After the set cleaning time, the second pipeline 12 returns to the initial position under the drive of the drive unit 3 to prevent the second pipeline 12 from blocking the loading or unloading of the silicon wafer.

[0035] Specifically, the driving unit 3 driving the second pipeline 12 to move to the re-cleaning area means that: the driving unit 3 first drives the rotating shaft 31 to rotate according to the control signal; the rotation of the rotating shaft 31 drives the rotating part 121 of the second pipeline 12 to move simultaneously until the rotating part 121 is aligned with the re-cleaning area. Here, the alignment of the rotating part 121 with the re-cleaning area means that the extension line of the rotating part 121 along its length direction passes through the re-cleaning area; after the rotating part 121 is aligned with the re-cleaning area, the driving unit 3 then drives the translation driver 32 to move according to the control signal; the translation driver 32 drives the extension part 122 to move on the rotating part 121; since the rotating part 121 is already aligned with the re-cleaning area, the extension part 122, driven by the translation driver 32, can move the port of the second pipeline 12 above the re-cleaning area and rinse the re-cleaning area through the port.

[0036] After the second pipeline 12 completes the enhanced rinsing of the re-cleaning area, the detection device scans the silicon wafer surface again to obtain the metal particle distribution map of the silicon wafer. If there are still areas on the silicon wafer surface with excessive metal particle content, the enhanced rinsing process of the second pipeline 12 on the re-cleaning area is repeated until the detection device detects that there are no areas on the silicon wafer surface with excessive metal particle content. This indicates that the edge cleaning of the silicon wafer has been improved and meets the requirements for pre-cleaning before the heat treatment of epitaxial silicon wafers.

[0037] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0038] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cleaning method for the edge of a silicon wafer, characterized in that, The cleaning method includes the following steps: The silicon wafer surface is cleaned using a cleaning unit; After cleaning, a detection unit is used to detect contaminants on the edge portion of the silicon wafer surface, identify the re-cleaning areas where contaminants exceed the standard on the edge portion of the silicon wafer surface, and obtain the location information of the re-cleaning areas; The control unit controls the cleaning unit to clean the silicon wafer again based on the location information; After the second cleaning, the detection unit performs contaminant detection on the silicon wafer surface, confirming that there are no areas with excessive contaminants in the re-cleaned areas at the edges of the silicon wafer surface. The cleaning unit is driven by a drive unit, and is in an initial position before cleaning begins. The control unit controls the cleaning unit to perform a second cleaning of the silicon wafer based on the location information, specifically including the following steps: The control unit sends a control signal to the drive unit based on the location information; The drive unit drives the second pipeline of the cleaning unit to move from the initial position to the re-cleaning area based on the control signal and sprays cleaning fluid into the re-cleaning area. After a fixed cleaning time, the cleaning ends, and the drive unit drives the second pipeline back to the initial position.

2. The cleaning method according to claim 1, characterized in that, The cleaning of the silicon wafer surface by the cleaning unit specifically includes the following steps: The driving unit drives the first conduit of the cleaning unit to move from the initial position to the center position of the silicon wafer, and the driving unit drives the second conduit of the cleaning unit to move from the initial position to the edge position of the silicon wafer; After the cleaning unit stops moving, the silicon wafer rotates around its own central axis under the drive of the support platform. The first and second pipelines simultaneously spray cleaning fluid onto the silicon wafer; After a fixed cleaning time, the cleaning ends, and the drive unit drives the first pipeline and the second pipeline back to the initial position.

3. The cleaning method according to claim 2, characterized in that, After cleaning, a detection unit is used to detect contaminants on the edge portion of the silicon wafer surface, identify areas on the edge portion of the silicon wafer surface with excessive contaminants requiring further cleaning, and obtain the location information of the areas requiring further cleaning. This process specifically includes the following steps: The detection unit performs an optical scan on the edge portion of the silicon wafer surface to obtain a metal particle distribution map of the edge portion of the silicon wafer surface. The detection unit identifies the re-cleaning area with excessive metal particle content on the edge portion of the silicon wafer surface based on the metal particle distribution map and obtains the location information of the re-cleaning area. The detection unit transmits the location information to the control unit.

4. The cleaning method according to claim 1, characterized in that, The drive unit drives the second pipeline to move from the initial position to the re-cleaning area based on the control signal, specifically including the following steps: The drive unit drives the rotating shaft to rotate based on the control signal. The rotating shaft drives the rotating part of the second pipeline to rotate in a plane parallel to the silicon wafer surface, so that the rotating part is aligned with the re-cleaning area. After the rotating part is aligned with the re-cleaning area, the driving unit drives the translation driver to move based on the control signal. The translation driver drives the extension of the second pipeline to move along the length direction of the rotating part, so that the spray port of the second pipeline reaches above the re-cleaning area.

5. A cleaning apparatus for silicon wafer edges, the apparatus being used to perform the cleaning method according to any one of claims 1 to 4, characterized in that, The cleaning device includes: A cleaning unit is used to clean the surface of a silicon wafer. The cleaning unit includes a first conduit that sprays cleaning fluid to the center of the silicon wafer and a second conduit that sprays cleaning fluid to the edge of the silicon wafer. The detection unit is used to detect contaminants on the edge portion of the silicon wafer surface, identify re-cleaning areas with excessive contaminants on the edge portion of the silicon wafer surface, and obtain the location information of the re-cleaning areas. A control unit configured to control the cleaning unit to clean the silicon wafer based on the location information; A drive unit, used to drive the cleaning unit to move, includes a rotary shaft and a translation driver, the translation driver being fixedly mounted on the rotary shaft. The first conduit is fixedly mounted on the rotating shaft, and the first conduit is configured to be driven by the rotating shaft to rotate in a plane parallel to the surface of the silicon wafer. The second conduit includes a rotating part and an extension part, the extension part being movably mounted on the rotating part. The cleaning device is configured such that the rotating part is fixedly mounted on the rotating shaft, the rotating part is perpendicular to the rotating shaft, and the rotating part rotates with the rotating shaft in a plane parallel to the surface of the silicon wafer. The extension part is fixedly connected to the translation driver, and the translation driver drives the extension part to move along the length direction of the rotating part.

6. The cleaning apparatus according to claim 5, characterized in that, The detection unit includes an optical microscope, which is configured to obtain a metal particle distribution map of the silicon wafer through optical scanning.

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