Method and system for improving uniformity of film layer after chemical mechanical polishing
By depositing a stop layer on the wafer and etching excessively thick areas, combined with chemical mechanical polishing, the problem of CMP equipment's inability to precisely control film uniformity was solved, achieving improved wafer film uniformity and enhanced device consistency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI IND U TECH RES INST
- Filing Date
- 2026-01-20
- Publication Date
- 2026-04-21
AI Technical Summary
In the existing technology, chemical mechanical polishing (CMP) equipment cannot accurately control the film thickness uniformity of local areas of the wafer, resulting in poor film uniformity after chemical mechanical polishing, which cannot meet the requirements of high-precision MEMS manufacturing.
After depositing a polishing dielectric layer on the wafer, the film thickness is measured and a thickness distribution map is generated. A stop layer is deposited and a compensation area is determined based on the distribution map. The stop layer in the excessively thick area is removed by photolithography and etching, and chemical mechanical polishing is performed to improve the uniformity of the film.
It significantly improves the uniformity of the film layer after chemical mechanical polishing, enhances the consistency and yield of the device, and meets the needs of high-precision MEMS manufacturing.
Smart Images
Figure CN121908861A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of integrated circuit manufacturing technology, and in particular relates to a method and system for improving the uniformity of film layers after chemical mechanical polishing. Background Technology
[0002] In the fields of microelectromechanical systems (MEMS) and integrated circuit manufacturing, as device structures become increasingly complex and three-dimensional, metal interconnect layers or other functional layers often form high step heights. For example, in some MEMS products, the metal layer step height can reach approximately 1 micrometer (μm). To ensure the accuracy of subsequent photolithography, etching, and other processes, as well as the reliability of multilayer structures, effective planarization of the wafer surface is essential. Typically, this requires depositing a thick dielectric layer (such as silicon oxide) on the metal step structure as a planarization layer, and then smoothing it using a chemical mechanical polishing (CMP) process to obtain a globally flat surface.
[0003] Currently, the industry commonly uses plasma-enhanced chemical vapor deposition (PECVD) to deposit this planarization oxide layer. However, the PECVD process suffers from poor uniformity in the deposited film thickness. In actual production, it has been found that to cover a 1-micron step and obtain sufficient process margin, an oxide layer with a thickness of up to 2.5 to 3 microns is often required. During this thick film deposition process, the equipment generates significant thickness differences from the center to the edge. Specifically, for every approximately 1-micron film thickness deposited, approximately 900 Å of additional thickness accumulates in a specific region at the wafer edge (e.g., the 10 o'clock to 11 o'clock direction). This systematic and directional thickness non-uniformity poses a significant challenge to the subsequent planarization CMP process.
[0004] Chemical mechanical polishing (CMP), as a mainstream global planarization technique, aims to eliminate thickness variations introduced by previous deposition processes through selective material removal. In existing technologies, CMP equipment can adjust the removal rate of wafer edge regions by varying the zone pressure of the polishing head (especially the outer pressure zone) to compensate for thicker edge areas. However, this adjustment method has a fundamental flaw: pressure adjustment acts on the entire circumferential edge of the wafer, making precise, localized control impossible. For example, while controlling the zone pressure of the polishing head may partially compensate for the thickness in the 10-11 o'clock direction where the wafer is thicker, other edge regions (such as 1-2 o'clock, 4-5 o'clock, and 7-8 o'clock directions) may also be over-polished due to increased pressure, leading to excessive thinning of the film in these areas and even defects such as dishing or erosion. Ultimately, the film thickness uniformity on the wafer surface is not effectively improved and may even deteriorate further, failing to meet the requirements of high-precision MEMS manufacturing.
[0005] To address the problems existing in the current technology, it is necessary to develop a method to improve the uniformity of the film layer after chemical mechanical polishing, so as to enhance the uniformity of the film layer after chemical mechanical polishing of wafers. Summary of the Invention
[0006] This invention provides a method and system for improving the uniformity of film layers after chemical mechanical polishing, which can significantly improve the uniformity of film layers after chemical mechanical polishing of wafers.
[0007] Other objects and advantages of the present invention can be further understood from the technical features disclosed herein.
[0008] To achieve one, some, or all of the above objectives or other objectives, the present invention provides a method for improving the uniformity of film layers after chemical mechanical polishing. The method involves depositing a polishing dielectric layer on a wafer with a device structure deposited thereon, measuring the film thickness at multiple measurement points on the polishing dielectric layer, and generating a thickness distribution map based on the thickness at the multiple measurement points; uniformly depositing a stop layer over the polishing dielectric layer globally; determining the pattern of compensation regions where the stop layer needs to be removed based on the thickness distribution map; patterning the stop layer according to the pattern of the compensation regions and etching the stop layer within the compensation regions, while retaining the stop layer outside the compensation regions; and after completing the etching of the stop layer in the compensation regions, performing chemical mechanical polishing on the wafer to the target polishing thickness.
[0009] Based on the thickness distribution map, the uniformity of the film thickness of the polishing medium layer is calculated; when the uniformity of the film thickness of the polishing medium layer is greater than 3%, the excessively thick area on the thickness distribution map is identified as a compensation area.
[0010] The method for finding the excessively thick areas on the thickness distribution map is as follows: a thickness baseline is set, which is calculated as 1.05 to 1.08 times the average thickness of the polishing medium layer; the areas on the thickness distribution map that exceed the thickness baseline are the excessively thick areas.
[0011] The thickness of the deposited stop layer is calculated using the following formula: Ts = Td × Nu × U × K / 2; Where Ts is the thickness of the stop layer to be deposited, Td is the average thickness of the dielectric layer, Nu is the percentage of dielectric layer thickness uniformity, U is the polishing selectivity ratio of the polishing slurry for the dielectric layer and the stop layer, and K is the polishing coefficient.
[0012] The selection of the types of the medium layer and the stop layer is related to the polishing selectivity ratio of the polishing slurry used in the chemical mechanical polishing process to the medium layer and the stop layer; the polishing selectivity ratio of the polishing slurry used in the chemical mechanical polishing process to the medium layer and the stop layer is greater than 1:1.
[0013] The stop layer is patterned according to the pattern of the compensation region, including: fabricating a photomask based on the pattern of the compensation region; applying photoresist on a wafer on which the stop layer is deposited; performing photolithography on the wafer using the photomask; and exposing the compensation region after development; etching the compensation region to remove the stop layer of the compensation region; and removing the remaining photoresist on the wafer surface after the stop layer etching of the compensation region is completed.
[0014] The remaining photoresist on the wafer surface is removed by an oxygen plasma treatment method.
[0015] Another technical solution of the present invention provides a system for improving the uniformity of film layers after chemical mechanical polishing, comprising: a deposition apparatus for sequentially depositing a dielectric layer and a stop layer on the wafer; a thickness measurement unit for measuring the thickness of the deposited dielectric layer; a data processing unit for generating a thickness distribution map based on the measured dielectric layer thickness, and determining a compensation region pattern for which the stop layer needs to be removed based on the thickness distribution map; a photolithography and etching apparatus for fabricating a photomask based on the compensation region pattern, using the photomask to perform photolithography on the wafer and then developing it to expose the compensation region on the wafer, and etching to remove the stop layer on the compensation region; and a chemical mechanical polishing apparatus for polishing the wafer after etching the stop layer in the compensation region.
[0016] The thickness of the stop layer deposited by the deposition equipment is calculated using the following formula: Ts = Td × Nu × U × K / 2; Wherein, Ts is the thickness of the stop layer to be deposited, Td is the average thickness of the dielectric layer, Nu is the percentage of dielectric layer thickness uniformity, U is the polishing selectivity ratio of the polishing slurry to the dielectric layer and the stop layer, and K is the polishing coefficient; the selection of the type of the dielectric layer and the stop layer is related to the polishing selectivity ratio of the polishing slurry used in the chemical mechanical polishing process to the dielectric layer and the stop layer; the polishing selectivity ratio of the polishing slurry used in the chemical mechanical polishing process to the dielectric layer and the stop layer is greater than 1:1.
[0017] The data processing unit determines the compensation area by: calculating the uniformity of the film thickness of the polishing medium layer based on the thickness distribution map; when the uniformity of the film thickness of the polishing medium layer is greater than 3%, the data processing unit finds the excessively thick area on the thickness distribution map as the compensation area; the method for finding the excessively thick area on the thickness distribution map is: setting a thickness baseline, the thickness baseline being calculated as 1.05 to 1.08 times the average film thickness of the polishing medium layer; the area on the thickness distribution map exceeding the thickness baseline is the excessively thick area.
[0018] Compared with the prior art, the beneficial effects of the present invention mainly include: The method for improving the uniformity of the film layer after chemical mechanical polishing provided by the present invention deposits a stop layer on top of the dielectric layer deposited in the prior art solution, and measures the thickness distribution of the dielectric layer to make a thickness distribution map. Based on the thickness distribution map, the area where the dielectric layer is too thick is determined as the compensation area. The stop layer on the compensation area is etched away. The deposition of the stop layer is precisely calculated by formula to control the thickness. Combined with the selection ratio of the dielectric layer and the stop layer of the polishing slurry, the excessively thick dielectric layer in the compensation area (the stop layer in the compensation area has been removed, and the remaining part in the compensation area is the dielectric layer) will be polished away simultaneously with the stop layer in the non-compensation area to ensure that the uniformity of the final wafer surface meets the polishing requirements. The method for improving the uniformity of the film layer after chemical mechanical polishing of the present invention can significantly improve the uniformity of the film layer after chemical mechanical polishing of the wafer, and at the same time improve the consistency, yield and long-term reliability of the device.
[0019] To make the above and other objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description
[0020] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0021] Figure 1This is a diagram showing the thickness distribution of the dielectric layer on a wafer with only a dielectric layer deposited in Example 1 before chemical mechanical polishing.
[0022] Figure 2 The image shows the film thickness distribution of the wafer in Example 1 that was not treated by the improved method of the present invention after chemical mechanical polishing.
[0023] Figure 3 This is a film thickness distribution diagram of the wafer processed by the improved method of the present invention in Example 1 after chemical mechanical polishing.
[0024] Figure 4 for Figure 2 as well as Figure 3 The diagram shows a comparison of the uniformity of the film thickness distribution. Detailed Implementation
[0025] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate preferred embodiments of the application. However, this application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.
[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0027] It should be understood that when an element or layer is referred to as being "on," "adjacent to," or "connected to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, regions, layers, doping types, and / or portions, these elements, components, regions, layers, doping types, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type, or portion from another element, component, region, layer, doping type, or portion. Therefore, without departing from the teachings of this application, the first element, component, region, layer, doping type, or portion discussed below may be referred to as a second element, component, region, layer, or portion.
[0028] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that when the terms “comprise” and / or “comprising” are used in this specification, the presence of the stated feature, integer, step, operation, element, and / or part is established, but the presence or addition of one or more other features, integers, steps, operations, elements, parts, and / or groups is not excluded. Meanwhile, when used herein, the term “and / or” includes any and all combinations of the associated listed items.
[0029] Embodiments of the invention are described herein with reference to cross-sectional views illustrating preferred embodiments (and intermediate structures) of this application, thus allowing for the anticipation of variations in the illustrated shapes due to, for example, manufacturing techniques and / or tolerances. Embodiments of this application should not be limited to the specific shapes of the regions shown herein, but rather include shape deviations due to, for example, manufacturing techniques. Therefore, the regions shown in the figures are substantially schematic, and their shapes do not represent the actual shapes of regions of the device, nor do they limit the scope of this application.
[0030] Example 1 Example 1 provides a method for improving the uniformity of film layers after chemical mechanical polishing. A polishing dielectric layer is deposited on a wafer with a device structure deposited thereon, and the thickness of the dielectric layer is measured at multiple measurement points. A thickness distribution map is generated based on the thickness of the multiple measurement points. A stop layer is uniformly deposited globally above the dielectric layer. Based on the thickness distribution map, a compensation region pattern is determined where the stop layer needs to be removed. According to the pattern of the compensation region, the stop layer is patterned and etched within the compensation region, retaining the stop layer outside the compensation region. After the stop layer etching of the compensation region is completed, the wafer is chemically mechanically polished to the target polishing thickness.
[0031] The following description, in conjunction with the accompanying drawings, details a method for improving the uniformity of a film layer after chemical mechanical polishing according to the present invention. The method includes the following steps: Step 1: Deposit a stop layer on the wafer on which the dielectric layer has been deposited.
[0032] High step heights are often formed on microelectromechanical systems (MEMS). To ensure the accuracy of subsequent photolithography, etching and other processes as well as the reliability of multilayer structures, the wafer surface must be effectively planarized.
[0033] Before planarization, a relatively thick dielectric layer (such as silicon oxide) is deposited on the metal step structure as a planarization layer, and the thickness of the deposited dielectric layer exceeds the height of the step device structure.
[0034] After the dielectric layer is deposited, a stop layer is deposited on top of the dielectric layer. The stop layer is deposited uniformly over the dielectric layer, and its thickness is determined according to the following formula: Ts = Td × Nu × U × K / 2; Where Ts is the thickness of the deposited stop layer, Td is the average thickness of the dielectric layer, Nu is the percentage of dielectric layer thickness uniformity, U is the polishing selectivity ratio of the polishing slurry for the dielectric layer and the stop layer, and K is the polishing coefficient. The calculation method for the uniformity percentage of dielectric layer thickness is: (maximum measured value - minimum measured value) ÷ total thickness ÷ 2 × 100%.
[0035] The types of deposited media and stop layers are selected based on the polishing selectivity ratio of the polishing slurry for the media and stop layers, which will not be described in detail here. The polishing steps are explained in detail below.
[0036] Step 2: Generate a dielectric layer thickness distribution map.
[0037] For a wafer with a deposited dielectric layer, the thickness of the deposited dielectric layer can be measured using optical measurement methods (such as reflectance spectroscopy) or probe measurement.
[0038] During measurement, the system selects several measurement points on the wafer. These selected measurement points are evenly distributed across various regions of the wafer. After measuring the dielectric layer thickness at multiple measurement points on the wafer, a dielectric layer thickness distribution map of the wafer is generated.
[0039] Step 3: Determine the compensation area.
[0040] The method for determining the compensation area is as follows: based on the thickness distribution map, calculate the uniformity of the film thickness of the polishing medium layer; when the uniformity of the film thickness of the polishing medium layer is greater than 3%, find the excessively thick area on the thickness distribution map as the compensation area.
[0041] The method for finding excessively thick areas on the thickness distribution map is as follows: set a thickness baseline. The thickness baseline is calculated as 1.05 to 1.08 times the average thickness of the polishing medium layer. Areas on the thickness distribution map that exceed the thickness baseline are considered excessively thick areas.
[0042] When identifying excessively thick regions, each measurement point on the thickness distribution map can be compared with the thickness baseline. Measurement points exceeding the thickness baseline are collected, and a compensation region graphic is formed based on the collected measurement points. When forming the compensation region graphic, graphics processing software can be used to plot measurement points on the thickness distribution map that can form continuous curves as curves and smooth them to obtain the compensation region graphic. This part of the technology is prior art and will not be described in detail in this application.
[0043] Step 4: Photolithography and etching of the compensation area.
[0044] Step 4-1: Create a light mask.
[0045] A photomask (photolithography mask) is fabricated based on the pattern of the compensation region, and the pattern of the compensation region is transferred onto the photomask. The specific fabrication process of the photomask is existing technology and will not be described in detail in this application.
[0046] Step 4-2: Photolithographic compensation area.
[0047] Photoresist is applied to a wafer with a stop layer deposited, and the wafer is photolithographically etched using a photomask. After development, the compensation area is exposed to facilitate the next etching operation.
[0048] Step 4-3: Etching compensation area.
[0049] The exposed compensation area is etched, and dry etching is generally used to remove the stop layer in the compensation area. The etching stops at the boundary between the dielectric layer and the stop layer.
[0050] Step 4-4: Remove residual photoresist from the wafer surface.
[0051] After etching the stop layer, remove the remaining photoresist from the wafer surface. The photoresist on the wafer surface can be removed using an oxygen plasma treatment process.
[0052] After removing the residual photoresist on the wafer surface, the stop layer in the compensation area is removed, while the stop layer in the non-compensation area is retained to facilitate subsequent polishing.
[0053] Step 5: Perform chemical mechanical polishing on the etched wafer.
[0054] When performing chemical mechanical polishing on the etched wafer, the polishing slurry used has different selectivity ratios for the dielectric layer and the stop layer. After completing step 4, the stop layer in the overly thick compensation area on the wafer has been removed, while a stop layer is deposited on the non-compensation area. The thickness of the stop layer deposited on the wafer, calculated in step 1, is sufficient to simultaneously thin the dielectric layer in the compensation area and remove the stop layer in the non-compensation area under the different polishing selectivity ratios of the polishing slurry during the polishing process, ultimately resulting in a dielectric layer film with good uniformity.
[0055] To achieve the above objectives, the polishing speed of the polishing slurry on the media layer needs to be greater than that on the stop layer. In other words, the polishing selectivity ratio of the polishing slurry used in chemical mechanical polishing for the media layer and the stop layer needs to be greater than 1:1.
[0056] For example, the polishing slurry used has a polishing selectivity ratio of 4:1 for the medium layer and the stop layer.
[0057] Based on the polishing selectivity requirements of the polishing slurry used in the above-mentioned chemical mechanical polishing treatment for the medium layer and the stop layer, the appropriate combination of medium layer and stop layer can be selected.
[0058] For example, when the dielectric layer is silicon oxide, the stop layer can be selected from silicon nitride, polycrystalline silicon, carbon-doped silicon nitride, or amorphous silicon.
[0059] The method for improving the uniformity of the film layer after chemical mechanical polishing (CMP) provided by this invention involves depositing a stop layer on top of the dielectric layer deposited in existing technologies, measuring the thickness distribution of the dielectric layer to create a thickness distribution map, identifying areas with excessively thick dielectric layers as compensation areas based on the thickness distribution map, and etching away the stop layer on the compensation areas. The deposition of the stop layer is precisely calculated using a formula to control its thickness. Combined with the selection ratio of the dielectric layer and the stop layer in the polishing slurry, the excessively thick dielectric layer in the compensation areas (where the stop layer has been removed, leaving only the dielectric layer) is polished away simultaneously with the stop layer in the non-compensation areas. This ensures that the final wafer surface uniformity meets the polishing requirements. This invention differs from existing technologies where adjusting the partition pressure of the polishing head leads to poor polishing uniformity. The method of improving the uniformity of the film layer after CMP of this invention can significantly improve the uniformity of the wafer film layer after CMP, while simultaneously enhancing device consistency, yield, and long-term reliability.
[0060] The following text is in the format of Figure 1-4 The following is an example of a specific wafer polishing process to illustrate the scheme of Embodiment 1.
[0061] like Figure 1 The thickness distribution diagram of the wafer with deposited dielectric layer (silicon oxide) is shown. It can be seen that there is a red area of excessive film thickness in the edge region from 10 o'clock to 12 o'clock.
[0062] Figure 2 for Figure 1 The wafer underwent CMP treatment (without the improved method described in Example 1), and the film thickness distribution was shown. During CMP treatment, the partition pressure of the polishing head was adjusted (to improve...). Figure 1 (The problem of excessive film thickness in the edge area from 10 o'clock to 12 o'clock) Figure 2 The film thickness of the wafer in the 10 o'clock to 12 o'clock region was significantly improved, but many areas of excessive film thickness (red area) appeared in other regions. The uniformity of the film layer of the wafer was poor after CMP treatment.
[0063] Figure 3 for Figure 1The wafer treated with the improvement method in Example 1 is shown in the film thickness distribution diagram after CMP treatment. It can be seen that after the improvement method in Example 1, the area of the red region on the entire wafer is significantly reduced, and it is no longer a large red region (the improved red overthick region is distributed in multiple regions on the wafer), and the film thickness uniformity is significantly improved.
[0064] Figure 4 for Figure 2 as well as Figure 3 The uniformity comparison diagram of the film thickness distribution shows that after the improvement method in Example 1, the difference in film thickness (the difference between the maximum and minimum values) before improvement was 900 Å, and the difference in film thickness after improvement by the method in Example 1 was 300 Å. At the same time, the mean standard error improved from 33.24 before improvement to 11.82. It can be seen that the improvement method in Example 1 can effectively improve the uniformity of the film after CMP treatment, and improve the consistency, yield and long-term reliability of the device.
[0065] Example 2 Example 2 provides a system for improving the uniformity of film layers after chemical mechanical polishing, comprising: a deposition apparatus for sequentially depositing a dielectric layer and a stop layer on a wafer; a thickness measurement unit for measuring the thickness of the deposited dielectric layer; a data processing unit for generating a thickness distribution map based on the measured dielectric layer thickness and determining a compensation region pattern for which the stop layer needs to be removed based on the thickness distribution map; a photolithography and etching apparatus for fabricating a photomask based on the compensation region pattern, using the photomask to perform photolithography on the wafer and then developing it to expose the compensation region on the wafer, and etching to remove the stop layer on the compensation region; and a chemical mechanical polishing apparatus for polishing the wafer after etching the stop layer in the compensation region.
[0066] The thickness of the stop layer deposited by the deposition equipment is calculated using the following formula: Ts = Td × Nu × U × K / 2; Where Ts is the thickness of the deposited stop layer, Td is the average thickness of the dielectric layer, Nu is the percentage of dielectric layer thickness uniformity, U is the polishing selectivity ratio of the polishing slurry for the dielectric layer and the stop layer, and K is the polishing coefficient. The selection of the type of dielectric layer and stop layer is related to the polishing selectivity ratio of the polishing slurry used in chemical mechanical polishing (CMP) to the dielectric layer and stop layer; the polishing selectivity ratio of the polishing slurry used in CMP to the dielectric layer and stop layer is greater than 1:1.
[0067] For example, the polishing slurry used has a polishing selectivity ratio of 4:1 for the dielectric layer and the stop layer. The appropriate combination of dielectric and stop layers can be selected based on the polishing selectivity ratio requirements of the polishing slurry used in the aforementioned chemical mechanical polishing treatment. For example, when the dielectric layer is silicon oxide, the stop layer can be selected from silicon nitride, polycrystalline silicon, silicon carbide-doped silicon nitride, or amorphous silicon.
[0068] The data processing unit determines the compensation area by: calculating the uniformity of the film thickness of the polishing medium layer based on the thickness distribution map; when the uniformity of the film thickness of the polishing medium layer is greater than 3%, the data processing unit finds the excessively thick area on the thickness distribution map as the compensation area; the method for finding the excessively thick area on the thickness distribution map is: setting a thickness baseline, the thickness baseline being calculated as 1.05 to 1.08 times the average film thickness of the polishing medium layer; the area on the thickness distribution map exceeding the thickness baseline is the excessively thick area.
[0069] Example 2 provides a system for improving the uniformity of a film layer after chemical mechanical polishing, used to perform the steps in a method for improving the uniformity of a film layer after chemical mechanical polishing in Example 1.
[0070] The present invention has provided a detailed description of a method and system for improving the uniformity of a film layer after chemical mechanical polishing. Specific examples have been used to illustrate the structure and working principle of the invention. The descriptions of the embodiments are merely for the purpose of helping to understand the method and core ideas of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.
Claims
1. A method for improving the uniformity of a film layer after chemical mechanical polishing, characterized in that, On a wafer with a device structure deposited, a polishing dielectric layer is deposited, and the film thickness at multiple measurement points on the polishing dielectric layer is measured. A thickness distribution map is generated based on the thickness at the multiple measurement points. A stop layer is uniformly deposited globally above the polishing medium layer; The graphic of the compensation area that needs to be removed from the stop layer is determined based on the thickness distribution map; Based on the pattern of the compensation region, the stop layer is patterned and the stop layer within the compensation region is etched, while the stop layer outside the compensation region is retained; After completing the stop layer etching of the compensation region, the wafer is subjected to chemical mechanical polishing to the target polishing thickness.
2. The method for improving the uniformity of the film layer after chemical mechanical polishing according to claim 1, characterized in that, Based on the thickness distribution map, the uniformity of the film thickness of the polishing medium layer is calculated; When the uniformity of the film thickness of the polishing medium layer is greater than 3%, the excessively thick area on the thickness distribution map is identified as the compensation area.
3. The method for improving the uniformity of the film layer after chemical mechanical polishing according to claim 2, characterized in that, The method for finding excessively thick areas on the thickness distribution map is as follows: a thickness baseline is set, which is calculated as 1.05 to 1.08 times the average thickness of the polishing medium layer. The area on the thickness distribution map that exceeds the thickness baseline is the excessively thick area.
4. The method for improving the uniformity of the film layer after chemical mechanical polishing according to claim 1, characterized in that, The thickness of the deposited stop layer is calculated using the following formula: Ts = Td × Nu × U × K / 2; Where Ts is the thickness of the deposited stop layer, Td is the average thickness of the dielectric layer, Nu is the percentage of dielectric layer thickness uniformity, U is the polishing selectivity ratio of the polishing slurry for the dielectric layer and the stop layer, and K is the polishing coefficient.
5. The method for improving the uniformity of the film layer after chemical mechanical polishing according to claim 1, characterized in that, The selection of the type of the medium layer and the stop layer is related to the polishing selectivity ratio of the polishing slurry used in the chemical mechanical polishing process for the medium layer and the stop layer; The polishing slurry used in the chemical mechanical polishing process has a polishing selectivity ratio of greater than 1:1 for the medium layer and the stop layer.
6. The method for improving the uniformity of a film layer after chemical mechanical polishing according to claim 1, characterized in that, Based on the pattern of the compensation region, the stop layer is patterned, including creating a photomask based on the pattern of the compensation region; Photoresist is applied to a wafer on which a stop layer has been deposited, the wafer is photolithographically etched using the photomask, and the compensation region is exposed after development. The compensation area is etched to remove the stop layer of the compensation area; After completing the stop layer etching of the compensation region, remove the remaining photoresist on the wafer surface.
7. The method for improving the uniformity of a film layer after chemical mechanical polishing according to claim 6, characterized in that, The remaining photoresist on the wafer surface is removed by an oxygen plasma treatment method.
8. A system for improving the uniformity of a film layer after chemical mechanical polishing, characterized in that, The system includes: A deposition apparatus sequentially deposits a dielectric layer and a stop layer on the wafer; A thickness measurement unit measures the thickness of the deposited dielectric layer; The data processing unit generates a thickness distribution map based on the measured thickness of the dielectric layer, and determines the compensation region pattern of the stop layer that needs to be removed based on the thickness distribution map. The photolithography and etching equipment is used to fabricate a photomask based on a compensation region pattern, and then the compensation region on the wafer is exposed after photolithography and development using the photomask. The stop layer on the compensation region is then etched away. A chemical mechanical polishing (CMP) device is used to polish the wafer after etching the stop layer in the compensation region.
9. The system for improving the uniformity of a film layer after chemical mechanical polishing according to claim 8, characterized in that, The thickness of the stop layer deposited by the deposition equipment is calculated using the following formula: Ts = Td × Nu × U × K / 2; Where Ts is the thickness of the deposited stop layer, Td is the average thickness of the dielectric layer, Nu is the percentage of dielectric layer thickness uniformity, U is the polishing selectivity ratio of the polishing slurry for the dielectric layer and the stop layer, and K is the polishing coefficient. The selection of the type of the medium layer and the stop layer is related to the polishing selectivity ratio of the polishing slurry used in the chemical mechanical polishing process for the medium layer and the stop layer; The polishing slurry used in the chemical mechanical polishing process has a polishing selectivity ratio of greater than 1:1 for the medium layer and the stop layer.
10. The system for improving the uniformity of a film layer after chemical mechanical polishing according to claim 8, characterized in that, The data processing unit determines the compensation area by: calculating the uniformity of the film thickness of the polishing medium layer based on the thickness distribution map; when the uniformity of the film thickness of the polishing medium layer is greater than 3%, the data processing unit finds the excessively thick area on the thickness distribution map as the compensation area; The method for finding excessively thick areas on the thickness distribution map is as follows: a thickness baseline is set, which is calculated as 1.05 to 1.08 times the average thickness of the polishing medium layer. The area on the thickness distribution map that exceeds the thickness baseline is the excessively thick area.