A method and system for film trimming

Abstract

The application discloses a film trimming method and system, and relates to the technical field of semiconductor film trimming, and comprises the following steps: obtaining a wafer to be trimmed after chemical mechanical polishing processing; adopting a preset measurement point distribution scheme to measure the thickness of the film layer to be trimmed before trimming to obtain pre-value thickness distribution data; determining local trimming amounts of different regions and scanning control parameters corresponding to the local trimming amounts according to the pre-value thickness distribution data; and performing differential trimming operations on the film layer to be trimmed based on the local trimming amounts and the scanning control parameters, wherein the measurement points include a first set of measurement points located in an edge region and a second set of measurement points located in a central region and an intermediate transition region, and the point density of the first set of measurement points in a unit area is greater than the point density of the second set of measurement points in a unit area. The scheme is used for improving the in-die thickness uniformity after trimming, and the measurement efficiency and equipment productivity are taken into account.

Description

Technical Field

[0001] This invention relates to the field of semiconductor thin film processing technology, and in particular to a thin film trimming method and system. Background Technology

[0002] In the manufacturing process of temperature-compensated surface acoustic wave (SAW) products, a silicon dioxide film layer needs to be formed on the wafer surface to achieve compensation and control of the device's frequency and temperature characteristics. After chemical mechanical polishing, the uniformity of the silicon dioxide film thickness within the wafer directly affects the consistency of the electrical parameters of the subsequent device. Therefore, it is usually necessary to measure the film thickness before the finishing operation and control the amount of subsequent local finishing based on the measurement results.

[0003] In existing processes, a fixed number of measurement points are typically used to pre-measure the thickness within the wafer. Then, a thin-film trimming device generates the corresponding work path and local trimming amount based on the measurement results. For example, by adjusting the scanning speed, dwell time, or scanning path, differentiated trimming of different areas can be achieved. Current solutions often use a 49-point measurement method to acquire the wafer thickness.

[0004] However, the 49-point measurement scheme has a relatively small number of measurement points, making it difficult to fully reflect the true thickness distribution within the wafer. When there are abnormally high or low points in a local area of ​​the wafer, it is easy to miss measurements, resulting in a deviation between the previous value data obtained by the thin film trimming equipment and the actual thickness distribution. At the same time, the existing 49-point scheme has insufficient coverage density in the wafer edge area. Since the thickness difference within the wafer usually includes the difference between the central area and the edge area, insufficient measurement of the edge area will make it difficult for the thin film trimming equipment to accurately identify edge thickness changes, leading to problems of under-trimming or over-trimming of the edge area.

[0005] Although the gridded full-area measurement scheme can obtain more accurate thickness distribution data, the number of gridded full-area measurement points is large, the measurement time is significantly increased, and it is easy to cause a decrease in equipment capacity, making it unsuitable for full implementation in mass production processes.

[0006] Therefore, how to improve the measurement accuracy of thickness distribution within a wafer while ensuring measurement efficiency, and how to improve the uniformity of thickness within the wafer after trimming, has become a technical problem that urgently needs to be solved. Summary of the Invention

[0007] The main objective of this invention is to provide a thin film trimming method and system, which aims to improve the measurement accuracy of thickness distribution within a wafer while ensuring measurement efficiency, and to improve the uniformity of thickness within the trimmed wafer.

[0008] To achieve the above objectives, this invention proposes a thin film trimming method, comprising: acquiring a wafer to be trimmed after chemical mechanical polishing, wherein the surface of the wafer to be trimmed has a trimmed film layer; measuring the thickness of the trimmed film layer using a preset measurement point distribution scheme to obtain pre-value thickness distribution data, wherein the measurement point distribution scheme includes 69, 79, or 99 measurement points, the measurement points including a first set of measurement points located in the edge region of the wafer to be trimmed and a second set of measurement points located in the central region and intermediate transition region of the wafer to be trimmed, and the point density of the first set of measurement points per unit area is greater than the point density of the second set of measurement points per unit area, so that the measurement points in the edge region cover the thickness variation of the edge region; determining the local trimming amount of different regions of the wafer to be trimmed and the scanning control parameters corresponding to the local trimming amount based on the pre-value thickness distribution data; and performing differentiated trimming operations on the trimmed film layer based on the local trimming amount and the scanning control parameters.

[0009] In some embodiments, the measurement point distribution scheme includes 79 measurement points.

[0010] In some embodiments, the wafer to be trimmed has an effective measurement area, the effective measurement area has a normalized radius, the normalized radius is the ratio of the distance from the measurement point to the center of the wafer to the effective radius of the wafer, the normalized radius corresponding to the edge region is 0.85 to 1.00, the normalized radius corresponding to the intermediate transition region is greater than 0.50 and less than 0.85, and the normalized radius corresponding to the center region is 0 to 0.50.

[0011] In some embodiments, for the wafer to be trimmed where the average thickness of the central region and / or the intermediate transition region is greater than the average thickness of the edge region, the distribution density of the first measurement point set is configured to preferentially cover the thickness gradient variation of the edge region, and the second measurement point set is configured based on the remaining area of ​​the wafer to be trimmed.

[0012] In some embodiments, prior to the step of obtaining the wafer to be repaired after chemical mechanical polishing, the method further includes: analyzing the thickness distribution characteristics within historical batches of wafers to determine that the difference between the average thickness of the central region and the average thickness of the edge region is greater than a preset thickness difference threshold.

[0013] In some embodiments, performing differentiated trimming operations on the film layer to be trimmed based on the local trimming amount and the scanning control parameters includes: the thin film trimming equipment using a serpentine scanning path to scan the wafer to be trimmed; for a first region in the previous thickness distribution data indicating that the film layer thickness is greater than the target thickness, reducing the scanning movement speed or increasing the local dwell time to increase the trimming amount in the first region; and for a second region in the previous thickness distribution data indicating that the film layer thickness is less than the target thickness, increasing the scanning movement speed or reducing the local dwell time to decrease the trimming amount in the second region.

[0014] In some embodiments, the scan control parameters further include at least one of scan energy, scan power, scan count, or local repetition count.

[0015] In some embodiments, after performing a differentiated trimming operation on the film layer to be trimmed based on the local trimming amount and the scanning control parameters, the method further includes: measuring the thickness of the trimmed film layer using a gridded full-area measurement scheme covering the effective area of ​​the wafer to be trimmed, and obtaining post-value thickness distribution data; and evaluating the intra-wafer thickness range and intra-wafer thickness non-uniformity of the film layer to be trimmed after trimming based on the post-value thickness distribution data.

[0016] Wherein, the intra-sheet thickness range is the difference between the maximum thickness value and the minimum thickness value, and the intra-sheet thickness non-uniformity is determined according to the formula...

[0017] Calculate, where, Indicates the thickness non-uniformity within the film. Indicates the maximum thickness value. Indicates the minimum thickness value. This represents the average thickness value.

[0018] In some embodiments, the gridded full-area measurement scheme refers to a gridded sampling scheme that covers the effective area of ​​the wafer to be trimmed, wherein the gridded sampling scheme samples the film thickness within the effective area according to a preset row and column spacing.

[0019] In some embodiments, the wafer to be repaired is a temperature-compensated surface acoustic wave product wafer, and the film to be repaired is a silicon dioxide film.

[0020] This invention also discloses a thin film trimming system, comprising: a measurement device for measuring the thickness of a film layer to be trimmed on the surface of a wafer to be trimmed after chemical mechanical polishing using a preset measurement point distribution scheme, thereby obtaining pre-value thickness distribution data; wherein the measurement point distribution scheme includes 69, 79, or 99 measurement points, the measurement points including a first set of measurement points located in the edge region of the wafer to be trimmed and a second set of measurement points located in the central region and intermediate transition region of the wafer to be trimmed, and the point density of the first set of measurement points per unit area is greater than the point density of the second set of measurement points per unit area; and a thin film trimming device for determining, based on the pre-value thickness distribution data, the local trimming amount of different regions of the wafer to be trimmed and the scanning control parameters corresponding to the local trimming amount, and performing differentiated trimming operations on the film layer to be trimmed based on the local trimming amount and the scanning control parameters.

[0021] The above technical solution has the following advantages: This invention uses a preset measurement point distribution scheme to measure the thickness of the film layer to be trimmed before trimming, and makes the point density of the first measurement point set in the edge region greater than that of the second measurement point set in the center region and the intermediate transition region in the unit area. This allows the thickness variation in the wafer edge region to be collected more fully, thereby improving the consistency between the previous thickness distribution data and the actual thickness distribution. The thin film trimming equipment can determine the local trimming amount and corresponding scanning control parameters of different regions based on more accurate previous thickness distribution data, thereby improving the accuracy of local trimming amount control, improving the uniformity of the thickness within the wafer after trimming, and avoiding the problems of excessive measurement time and reduced equipment capacity caused by the gridded full-area measurement scheme. Attached Figure Description

[0022] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a flowchart of a thin film trimming method provided in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of the distribution of 49 measurement points provided in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of the distribution of 79 measurement points provided in an embodiment of the present invention.

[0025] Figure 4 A comparative diagram of the point distribution of the 49-point, 69-point, 79-point, 99-point and gridded full-area measurement schemes provided in the embodiments of the present invention.

[0026] Figure 5This is a schematic diagram of the thickness distribution before trimming corresponding to different measurement schemes provided in the embodiments of the present invention.

[0027] Figure 6 This is a schematic diagram comparing the thickness distribution of the entire gridded area after trimming, corresponding to different measurement schemes provided in the embodiments of the present invention.

[0028] Figure 7 This is a structural block diagram of a thin film trimming system provided in an embodiment of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] In the manufacturing process of temperature-compensated surface acoustic wave (TC-SAW) products, the silicon dioxide on the wafer surface (… The uniformity of the film thickness within the wafer after chemical mechanical polishing directly affects the consistency of the electrical parameters of subsequent devices. Therefore, before performing thin film trimming, it is necessary to first trim the silicon dioxide (SiO2). Thickness measurement of the film layer is performed to obtain the on-wafer thickness distribution data before trimming operations, which serves as the basis for subsequent calculation of trimming amount and control of the operation path. Current processes typically use 49 measurement points to measure the thickness within the wafer. However, this 49-point measurement scheme suffers from a limited number of measurement points, failing to fully reflect the true thickness distribution within the wafer, especially prone to missing measurement points when there are abnormally high or low thicknesses in localized areas. More importantly, the thickness difference within the wafer includes the difference between the central and edge regions, and the existing 49-point scheme has severely insufficient coverage density in the edge regions, making it difficult for the thin film trimming equipment to accurately determine the true thickness of the edge regions, easily leading to under- or over-trimming of the edge regions. While a gridded full-area measurement scheme could obtain a more accurate on-wafer thickness distribution, the sheer number of measurement points significantly increases measurement time, resulting in a substantial decrease in equipment capacity, making it unsuitable for direct full-scale adoption in mass production processes.

[0031] refer to Figure 1 Embodiment 1 of the present invention provides a thin film trimming method. The first step of the method is to obtain a wafer to be trimmed after chemical mechanical polishing. The surface of the wafer to be trimmed has a trimming film layer. Specifically, the wafer to be trimmed is a temperature-compensated surface acoustic wave product wafer, and the trimming film layer is specifically silicon dioxide (SiO2). ) Film layer. Before obtaining the wafer to be trimmed, the method also includes a step of analyzing the thickness distribution characteristics within the wafers of historical batches. Through historical data analysis, it is determined that the difference between the average thickness of the central region and the average thickness of the edge region is greater than a preset thickness difference threshold. This difference is usually manifested as the average thickness of the central region and / or the intermediate transition region being greater than the average thickness of the edge region, or there being a significant thickness gradient change between the center and the edge.

[0032] After acquiring the wafer to be trimmed, a metrology device is used to measure the thickness of the film layer to be trimmed based on a preset measurement point distribution scheme, in order to obtain the previous thickness distribution data. To achieve an optimal balance between measurement accuracy and equipment throughput, this measurement point distribution scheme includes 69, 79, or 99 measurement points. (Reference) Figures 2 to 4 In this embodiment, the number of measurement points is set to 79. These 79 measurement points are not randomly or uniformly laid out, but include a first set of measurement points located in the edge region and a second set of measurement points located in the central region and the intermediate transition region. The point density of the first set of measurement points per unit area is greater than that of the second set of measurement points per unit area, so that the measurement points in the edge region of the wafer to be repaired can cover the thickness variation of the edge region.

[0033] In a specific example, 79 measurement points are distributed in multiple concentric rings. The position of each measurement point is determined by the normalized radius r and the polar angle θ. The point density per unit area of ​​the first set of measurement points located in the range of normalized radius 0.85 to 1.00 is greater than that of the second set of measurement points located in the range of normalized radius 0 to 0.85. The normalized radius, number of points per ring, and angular interval of each concentric ring can be set according to Table 1.

[0034] Table 1. Example of distribution parameters for 79 measurement points

[0035] Specifically, the wafer to be repaired has an effective measurement area with a normalized radius, which is the ratio of the distance from the measurement point to the wafer's center to the wafer's effective radius. The normalized radius for the edge region is 0.85 to 1.00, for the intermediate transition region it is greater than 0.50 and less than 0.85, and for the center region it is 0 to 0.50. For wafers to be repaired where the average thickness of the center region and / or the intermediate transition region is greater than the average thickness of the edge region, when configuring measurement points, the distribution density of the first set of measurement points is prioritized to cover the thickness gradient changes in the edge region. After ensuring high-density sampling in areas with edge anomalies or large gradient changes, a second set of measurement points is configured based on the remaining area of ​​the wafer to be repaired. This edge-priority point arrangement strategy overcomes the deficiency of the traditional 49-point scheme, which easily misses areas with abnormal edge thickness. Compared to the gridded full-area measurement scheme, the 79-point scheme reduces the number of measurement points. Although the measurement time per piece increases from about 90s to about 135s, this only affects the thickness measurement single step and can be applied to mass production processes.

[0036] After obtaining relatively accurate preliminary thickness distribution data, the thin film trimming equipment determines the local trimming amount and corresponding scanning control parameters for different regions of the wafer to be trimmed based on the preliminary thickness distribution data. Because the preliminary data more closely matches the actual edge gradient and center undulation within the wafer, the local trimming amount and corresponding scanning control parameters generated by the thin film trimming equipment are more accurate. Subsequently, the thin film trimming equipment performs differentiated trimming operations on the film layer to be trimmed based on the local trimming amount and scanning control parameters.

[0037] When performing differentiated trimming operations, the thin film trimming equipment uses a serpentine scanning path to scan the wafer to be trimmed. For the first region, where the previous thickness distribution data indicates that the film thickness is greater than the target thickness, the thin film trimming equipment adopts a strategy of reducing the scanning speed or increasing the local dwell time to increase the trimming amount in the first region. For the second region, where the previous thickness distribution data indicates that the film thickness is less than the target thickness, the thin film trimming equipment adopts a strategy of increasing the scanning speed or decreasing the local dwell time to decrease the trimming amount in the second region. In addition to adjusting the speed and dwell time, the scanning control parameters can also include at least one of the following: scanning energy, scanning power, number of scans, or number of local repetitions. This multi-dimensional adjustment of operation parameters, combined with accurate previous value input, enables high control precision in the allocation of trimming amount.

[0038] refer to Figure 5 and Figure 6To verify and close the loop control of the trimming effect, after performing differentiated trimming operations on the film layer to be trimmed based on local trimming amount and scanning control parameters, the method also includes a step of measuring the thickness of the trimmed film layer using a gridded full-area measurement scheme to obtain post-value thickness distribution data. The gridded full-area measurement scheme refers to a gridded sampling scheme covering the effective area of ​​the wafer to be trimmed. The gridded sampling scheme samples the film layer thickness within the effective area according to a preset row and column spacing. Based on the post-value thickness distribution data, the intra-wafer thickness range and intra-wafer thickness non-uniformity of the trimmed film layer are evaluated. The intra-wafer thickness range is the difference between the maximum and minimum thickness values, and the intra-wafer thickness non-uniformity is calculated according to the formula...

[0039] Calculate, where, Indicates the thickness non-uniformity within the film. Indicates the maximum thickness value. Indicates the minimum thickness value. This represents the average thickness value. Experimental results show that, after adopting the 79-point edge-first measurement scheme provided in this embodiment, the thickness non-uniformity within the wafer after trimming can be reduced from approximately 2.138% to approximately 1.278%, and the thickness range within the wafer can be reduced from approximately 60.076 nm to approximately 38.419 nm. This embodiment addresses the reason why thickness differences are concentrated at the edges by proposing a targeted 79-point edge-first measurement arrangement. Without introducing complex gridded full-area scanning equipment, it improves the uniformity within the wafer while controlling the increase in measurement time, solving the technical problem of not being able to balance measurement efficiency and trimming accuracy in the prior art.

[0040] refer to Figure 7Embodiment 2 of the present invention provides a thin film trimming system, which specifically includes a measurement device and a thin film trimming device. The measurement device is used to measure the thickness of the film layer to be trimmed on the surface of the wafer to be trimmed after chemical mechanical polishing using a preset measurement point distribution scheme, thereby obtaining the previous thickness distribution data. The measurement point distribution scheme includes 69, 79, or 99 measurement points, and the measurement points include a first set of measurement points located in the edge region and a second set of measurement points located in the central region and the intermediate transition region. The point density of the first set of measurement points per unit area is greater than that of the second set of measurement points per unit area, so that the measurement points in the edge region of the wafer to be trimmed can cover the thickness variation in the edge region. The thin film trimming device is used to determine the local trimming amount and the corresponding scanning control parameters for different regions of the wafer to be trimmed based on the previous thickness distribution data, and to perform differentiated trimming operations on the film layer to be trimmed based on the local trimming amount and the scanning control parameters. The specific measurement point layout logic of the measurement equipment and the specific operation control logic of the film trimming equipment correspond to the film trimming method in Example 1. Through this system architecture, relatively accurate preceding value guidance data can be provided for the film trimming equipment without significantly increasing the equipment running time.

[0041] Embodiment 3 of this invention further expands and deepens the aforementioned embodiments. In actual large-scale mass production, the arrangement of measurement points is not static but can be dynamically adjusted based on historical batch data. When a product or a specific measurement device is found to have consistently thinner edge thickness, the measurement device can further increase the distribution density of edge measurement points. When a product is found to have abnormal thickness in a specific local area, the measurement device can add additional measurement points in the corresponding local area. After the previous thickness distribution data determined by the measurement device is input into the film trimming device, the film trimming device's control method for the local trimming amount and scanning control parameters is not limited to adjusting the moving speed or dwell time. The film trimming device can also change the local trimming amount by adjusting at least one of the scanning energy, scanning power, number of scans, or number of local repetitions. This multi-parameter fusion control method gives the trimming process higher freedom and accuracy.

[0042] refer to Figures 4 to 6To verify the impact of different measurement point numbers on the final trimming effect, this embodiment also provides a comparative verification process for different point schemes. Using the same type of wafer to be trimmed, 49-point, 69-point, 79-point, 99-point, and gridded full-area pre-value measurement schemes were constructed respectively. Each scheme was used for pre-trimming measurement, and after the differentiated trimming operations were completed, the gridded full-area measurement scheme was uniformly used for post-value measurement evaluation. Verification data shows that the in-wafer thickness non-uniformity after trimming is approximately 2.138% when using the 49-point measurement scheme, reduced to approximately 1.546% when using the 69-point measurement scheme, reduced to approximately 1.278% when using the 79-point measurement scheme, approximately 1.324% when using the 99-point measurement scheme, and approximately 0.752% when using the gridded full-area measurement scheme.

[0043] Comparative data shows that increasing the number of measurement points can improve the overall uniformity of the trimmed wafer, but more points do not necessarily mean better results. The 99-point scheme adds more points in the central region compared to the 79-point scheme, but does not bring significant improvement in uniformity, further confirming the inference that thickness anomalies are mainly concentrated in the edge regions. Considering the impact of single-wafer measurement time on overall production capacity, the 79-point scheme maintains a reasonable equipment output rate while ensuring high trimming accuracy, and can be considered as an implementation option in mass production environments. The solution provided by this invention is not only applicable to the silicon dioxide film layer of temperature-compensated surface acoustic wave products, but can also be extended to other thin-film processes that require guidance from the previous film thickness distribution for local trimming operations, such as trimming processes after planarization of microelectromechanical systems (MEMS) devices or semiconductor thin films.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features, and such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for trimming thin films, characterized in that, include: Obtain a wafer to be repaired after chemical mechanical polishing, wherein the surface of the wafer to be repaired has a repair film layer; The thickness of the film layer to be repaired is measured before repair using a preset measurement point distribution scheme to obtain the previous thickness distribution data. The measurement point distribution scheme includes 69, 79, or 99 measurement points. These measurement points include a first set of measurement points located in the edge region of the wafer to be repaired and a second set of measurement points located in the central region and intermediate transition region of the wafer. The point density of the first set of measurement points per unit area is greater than that of the second set of measurement points per unit area, so that the measurement points in the edge region cover the thickness variation in the edge region. Based on the previous thickness distribution data, the local repair amount for different regions of the wafer to be repaired and the corresponding scanning control parameters are determined. Based on the local repair amount and the scanning control parameters, a differentiated repair operation is performed on the film layer to be repaired.

2. The method according to claim 1, characterized in that, The measurement point distribution scheme includes 79 measurement points.

3. The method according to claim 1, characterized in that, The wafer to be trimmed has an effective measurement area, which has a normalized radius. The normalized radius is the ratio of the distance from the measurement point to the center of the wafer to the effective radius of the wafer. The normalized radius corresponding to the edge region is 0.85 to 1.00, the normalized radius corresponding to the intermediate transition region is greater than 0.50 and less than 0.85, and the normalized radius corresponding to the center region is 0 to 0.

50.

4. The method according to claim 3, characterized in that, For the wafer to be trimmed where the average thickness of the central region and / or the intermediate transition region is greater than the average thickness of the edge region, the distribution density of the first measurement point set is configured to preferentially cover the thickness gradient change of the edge region, and the second measurement point set is configured based on the remaining area of ​​the wafer to be trimmed.

5. The method according to claim 1, characterized in that, Before the step of obtaining the wafer to be repaired after chemical mechanical polishing, the method further includes: analyzing the thickness distribution characteristics within the wafers of historical batches to determine that the difference between the average thickness of the central region and the average thickness of the edge region is greater than a preset thickness difference threshold.

6. The method according to claim 1, characterized in that, The step of performing differentiated trimming operations on the film layer to be trimmed based on the local trimming amount and the scanning control parameters includes: the thin film trimming equipment using a serpentine scanning path to scan the wafer to be trimmed; for a first region in the previous thickness distribution data indicating that the film layer thickness is greater than the target thickness, reducing the scanning speed or increasing the local dwell time to increase the trimming amount in the first region; and for a second region in the previous thickness distribution data indicating that the film layer thickness is less than the target thickness, increasing the scanning speed or reducing the local dwell time to decrease the trimming amount in the second region.

7. The method according to claim 6, characterized in that, The scanning control parameters also include at least one of scanning energy, scanning power, number of scans, or number of local repetitive operations.

8. The method according to claim 1, characterized in that, After performing differentiated trimming on the film layer to be trimmed based on the local trimming amount and the scanning control parameters, the method further includes: measuring the thickness of the trimmed film layer using a gridded full-area measurement scheme covering the effective area of ​​the wafer to be trimmed, and obtaining post-value thickness distribution data; and evaluating the intra-wafer thickness range and intra-wafer thickness non-uniformity of the film layer to be trimmed after trimming based on the post-value thickness distribution data.

9. The method according to any one of claims 1 to 8, characterized in that, The wafer to be repaired is a temperature-compensated surface acoustic wave product wafer, and the film to be repaired is a silicon dioxide film.

10. A thin film trimming system, characterized in that, include: A measurement device is used to measure the thickness of the film layer to be repaired on the surface of a wafer to be repaired after chemical mechanical polishing using a preset measurement point distribution scheme, and to obtain the previous thickness distribution data; wherein, the measurement point distribution scheme includes 69, 79 or 99 measurement points, the measurement points include a first set of measurement points located in the edge region of the wafer to be repaired and a second set of measurement points located in the central region and intermediate transition region of the wafer to be repaired, and the point density of the first set of measurement points per unit area is greater than the point density of the second set of measurement points per unit area; A thin film trimming device is used to determine the local trimming amount and the corresponding scanning control parameters of different regions of the wafer to be trimmed based on the previous thickness distribution data, and to perform differentiated trimming operations on the film layer to be trimmed based on the local trimming amount and the scanning control parameters.

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