A method for improving wafer edge grinding rate

Abstract

The present invention provides a method for improving the grinding rate of a wafer edge, the method comprising: grinding a wafer using a chemical mechanical grinding device, and reducing the hardness of an adsorption film edge by 1-4SHA, while keeping the hardness of other regions of the adsorption film unchanged; the ratio of the width of the adsorption film edge to the radius of the adsorption film is (0.04-0.07):1. By adjusting the hardness of the adsorption film edge and controlling the hardness of other regions of the adsorption film to remain unchanged, combined with regulating the ratio of edge adjustment, without changing the grinding parameters, the grinding rate of the wafer edge is improved without affecting the grinding rate of the wafer center, thereby improving the wafer yield, and having good industrial application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical mechanical polishing and relates to a method for improving the polishing rate of a wafer edge. Background Art

[0002] With the rapid development of ultra-large scale integration (ULSI), the manufacturing process of integrated circuits has become more and more complex and sophisticated. In order to improve the integration level and reduce the manufacturing cost, the feature size of the components is getting smaller and smaller, and the number of components per unit area of ​​the chip is increasing. Planar wiring can no longer meet the requirements of high-density distribution of components. Only multi-layer wiring technology can be used to utilize the vertical space of the chip to further improve the integration density of the device. For this reason, in the wafer processing stage of the chip preparation process, deposition technology is often required to form a thin film as the basis for realizing multi-layer wiring technology. Common deposition technologies include physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD) and electrochemical plating.

[0003] However, as the thin film layers are deposited one after another, the surface of the wafer becomes uneven, which is extremely unfavorable for subsequent pattern production. Therefore, the wafer usually needs to be planarized. Planarization can effectively improve the surface morphology and remove surface defects such as rough surface, agglomerated materials, lattice damage, scratches and contaminated layers or materials.

[0004] At present, Chemical Mechanical Polishing (CMP) is the best method to achieve overall flatness of the wafer surface, especially after the semiconductor manufacturing process entered the sub-micron field, CMP has become an indispensable manufacturing process technology. Membrane refers to the adsorption film, which mainly controls the air pressure to achieve the purpose of absorbing the wafer and applying a certain pressure to the wafer surface, thereby adjusting the wafer surface polishing rate by controlling the pressure.

[0005] However, during the polishing process, the edge of the adsorption film is subject to the dual effects of the airbag pressure and the clamping components, so the polishing uniformity of the edge is often worse than that of the middle area, which results in performance differences in the devices processed in the edge area of ​​the wafer. Generally speaking, the larger the controllable area of ​​the CMP edge area, the larger the effective area in the wafer where devices can be actually produced. Therefore, improving the grinding efficiency of the CMP edge area is an important task to improve the wafer yield.

[0006] At present, the slow grinding rate of the wafer edge is mainly reflected in the small amount of wafer edge removal. Improving the grinding rate of the wafer edge can solve the problem of residues after CMP, improve the utilization rate of the wafer, and thus achieve an increase in yield. CN107052984A discloses a method for optimizing the flatness of the wafer edge area in a chemical mechanical planarization process, the steps of which are: using a film thickness measuring instrument to measure the surface morphology of the wafer, calculating and comparing the average film thickness of the edge area and the center area; using a step-by-step planarization method that combines adjusting the pressure of the retaining ring and changing the speed difference between the polishing disk and the polishing head on the 1# polishing disk to perform global rough polishing; using a step-by-step planarization method that combines adjusting the pressure of the retaining ring and changing the speed difference between the polishing disk and the polishing head on the 2# polishing disk to improve the flatness of the edge area; using low-pressure plasma water on the 3# polishing disk to rinse the wafer surface. The improvement strategy for the wafer edge area on the 1# and 2# polishing disks is: according to the wafer edge film thickness and the center film thickness value, adjust the retaining ring pressure and change the speed difference between the polishing disk and the polishing head.

[0007] However, the above method to improve the wafer edge grinding rate mainly relies on adjusting the pressure of the retaining ring in chemical mechanical grinding. However, the space for adjusting the pressure parameters of the equipment is limited and there is an upper limit to the specifications. When a large pressure is applied to the retaining ring and the wafer edge grinding rate is still very low, it is difficult to proceed by adjusting the pressure. At the same time, when the pressure applied by the retaining ring is too large, it will accelerate the wear of the grinding pad and the retaining ring.

[0008] In summary, providing a new method for improving the wafer edge grinding rate is an urgent problem to be solved by those skilled in the art. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for improving the grinding rate of wafer edges. By adjusting the hardness of the edge of the adsorption film and controlling the hardness of other areas of the adsorption film to remain unchanged, combined with regulating the ratio of edge adjustment, there is no need to change the grinding parameters. Without affecting the grinding rate of the center of the wafer, the grinding rate of the wafer edge is improved, thereby improving the wafer yield, and having good industrial application prospects.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] The present invention provides a method for improving a wafer edge grinding rate, the method comprising:

[0012] The wafer is ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film is reduced by 1-4 SHA, while the hardness of other areas of the adsorption film remains unchanged;

[0013] The ratio of the width of the edge of the adsorption film to the radius of the adsorption film is (0.04-0.07):1, for example, it can be 0.042:1, 0.045:1, 0.046:1, 0.048:1, 0.05:1, 0.052:1, 0.055:1, 0.056:1, 0.058:1, 0.06:1, 0.062:1, 0.065:1, 0.066:1 or 0.068:1, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0014] In the present invention, the hardness of the edge of the adsorption film is reduced by 1-4 SHA, for example, it can be 1.2 SHA, 1.5 SHA, 1.6 SHA, 1.8 SHA, 2 SHA, 2.2 SHA, 2.5 SHA, 2.6 SHA, 2.8 SHA, 3 SHA, 3.2 SHA, 3.5 SHA, 3.6 SHA or 3.8 SHA, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0015] In the present invention, chemical mechanical polishing is an important operation for wafer surface flattening, and the uniformity of each part of its surface grinding needs to be guaranteed, but according to the structural characteristics of wafer and grinding equipment, the grinding degree of wafer edge region is often lower than that of central region, and thus the grinding rate of wafer edge needs to be improved; the present invention adjusts the hardness of adsorption film edge by changing the physical parameters of adsorption film, and the hardness reduction is controlled within the range of 1-4SHA and the width of adsorption film edge and the radius of adsorption film (0.04-0.07): 1, under the condition of constant applied pressure, that is, without affecting the wafer center grinding rate, to improve the output pressure actually transmitted to the wafer edge region, without changing the grinding parameters, and without adjusting the structure of adsorption film, the effect of improving the wafer edge grinding rate can be achieved, and then the problem of residue causing the wafer edge grinding rate to be unstable in the initial stage of grinding is avoided, and the yield of wafer production is improved. The method is simple to operate, low in cost, and has good industrial application prospects.

[0016] It is worth noting that compared with the traditional method of applying pressure by improving the retaining ring and the grinding head, the method of the present invention is more flexible and does not have the problem of limited adjustment space of the former. By adjusting the hardness of the edge of the adsorption film and controlling the hardness of other areas of the adsorption film to remain unchanged, combined with the ratio of edge adjustment, the output pressure actually transmitted to the edge area of ​​the wafer is improved, thereby improving the wafer edge grinding rate; it can also better adapt to the shape changes of the wafer edge, reduce local pressure concentration during the grinding process, and thus improve the grinding uniformity of the wafer edge area; it can better absorb and disperse the grinding pressure during the grinding process, reduce pressure fluctuations, and thus improve the stability of the grinding process.

[0017] As a preferred technical solution of the present invention, the hardness of the edge of the adsorption film is reduced by 2-3 SHA, for example, it can be 2.1 SHA, 2.2 SHA, 2.3 SHA, 2.4 SHA, 2.5 SHA, 2.6 SHA, 2.7 SHA, 2.8 SHA or 2.9 SHA, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0018] As a preferred technical solution of the present invention, the hardness of the edge of the adsorption film is 37-39.5SHA, for example, it can be 37.2SHA, 37.5SHA, 37.6SHA, 37.8SHA, 38SHA, 38.2SHA, 38.5SHA, 38.6SHA, 38.8SHA, 39SHA, 39.2SHA or 39.4SHA, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] Preferably, the hardness of other areas of the adsorption film is greater than 40SHA, for example, it can be 40.2SHA, 40.5SHA, 40.6SHA, 40.8SHA, 41SHA, 41.2SHA, 41.5SHA, 41.6SHA, 41.8SHA, 42SHA or 43SHA, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0020] In the present invention, before the hardness of the adsorption film is adjusted, the hardness of the entire adsorption film is uniform, but because its edge hardness is relatively high, it is not conducive to the transmission of the output pressure, resulting in a low polishing rate at the edge of the wafer, and then the problem of residue retention occurs, resulting in a decrease in the yield of the wafer; therefore, the hardness of the edge of the adsorption film is adjusted to improve the output pressure actually transmitted to the edge area of ​​the wafer, thereby increasing the polishing rate of the edge of the wafer without basically affecting the polishing rate of the center of the wafer.

[0021] As a preferred technical solution of the present invention, the ratio of the width of the edge of the adsorption film to the radius of the adsorption film is (0.04-0.05):1, for example, it can be 0.041:1, 0.042:1, 0.043:1, 0.044:1, 0.045:1, 0.046:1, 0.047:1, 0.048:1 or 0.049:1, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0022] As a preferred technical solution of the present invention, the thickness of the adsorption film is 0.65-0.85 mm, for example, it can be 0.66 mm, 0.68 mm, 0.7 mm, 0.72 mm, 0.74 mm, 0.75 mm, 0.76 mm, 0.78 mm, 0.8 mm, 0.82 mm or 0.84 mm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the adsorption film is made of silica gel.

[0024] As a preferred technical solution of the present invention, the preparation method of the adsorption membrane comprises: placing silica gel raw materials in a mold and performing pressure molding to obtain the adsorption membrane.

[0025] Preferably, during the press molding, the temperature of the edge of the mold is controlled to be lower than the temperature of other areas of the mold, and the difference between the two is 5-10°C, for example, it can be 5.5°C, 6°C, 6.5°C, 7°C, 7.5°C, 8°C, 8.5°C, 9°C or 9.5°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0026] In the present invention, during the compression molding process of the adsorption film, the hardness of the edge of the adsorption film is effectively reduced by reducing the temperature of the edge of the adsorption film.

[0027] As a preferred technical solution of the present invention, the chemical mechanical polishing equipment is provided with a polishing head, a polishing pad and a polishing table in sequence from top to bottom; the structural components of the polishing head include an adsorption film and a retaining ring, and the wafer is located between the adsorption film and the polishing pad; the retaining ring is used to fix the wafer.

[0028] In the present invention, the chemical mechanical polishing equipment can be the equipment conventionally used in the prior art, and there is no need to adjust the structure of the adsorption film.

[0029] Preferably, during the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate.

[0030] As a preferred technical solution of the present invention, during the grinding, the pressure applied by the grinding head to the wafer is 3-4psi, for example, it can be 3.1psi, 3.2psi, 3.3psi, 3.4psi, 3.5psi, 3.6psi, 3.7psi, 3.8psi or 3.9psi, and the pressure applied to the retaining ring is 5-6psi, for example, it can be 5.1psi, 5.2psi, 5.3psi, 5.4psi, 5.5psi, 5.6psi, 5.7psi, 5.8psi or 5.9psi, but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0031] As a preferred technical solution of the present invention, during the grinding, the rotation speed of the grinding head is 85-90r / min, for example, it can be 86r / min, 87r / min, 88r / min or 89r / min, etc., and the rotation speed of the grinding pad is 90-95r / min, for example, it can be 91r / min, 92r / min, 93r / min or 94r / min, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] In the present invention, there is no need to change the parameter settings of the grinding equipment, and the effect of improving the grinding rate of the wafer edge can be achieved by adjusting the hardness of the edge of the adsorption film.

[0033] As a preferred technical solution of the present invention, the method comprises:

[0034] The wafer is ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film is reduced by 1-4 SHA, while the hardness of other areas of the adsorption film remains unchanged;

[0035] The hardness of the edge of the adsorption film is 37-39.5SHA; the hardness of other areas of the adsorption film is greater than the hardness of the edge of the adsorption film; the ratio of the width of the edge of the adsorption film to the radius of the adsorption film is (0.04-0.07):1; the thickness of the adsorption film is 0.65-0.85mm; the material of the adsorption film includes silica gel; the preparation method of the adsorption film includes: placing the silica gel raw material in a mold and performing pressure molding; during the pressure molding, controlling the temperature of the edge of the mold to be lower than the temperature of other areas of the mold, and the difference between the two is 5-10°C;

[0036] The chemical mechanical polishing equipment is provided with a polishing head, a polishing pad and a polishing table in order from top to bottom; the structural components of the polishing head include an adsorption film and a retaining ring, and the wafer is located between the adsorption film and the polishing pad; the retaining ring is used to fix the wafer;

[0037] During the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate; during the grinding, the pressure applied by the grinding head to the wafer is 3-4psi, and the pressure applied to the retaining ring is 5-6psi; during the grinding, the rotation speed of the grinding head is 85-90r / min, and the rotation speed of the grinding pad is 90-95r / min.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The method provided by the present invention improves the output pressure actually transmitted to the edge area of ​​the wafer by changing the physical property parameters of the adsorption film, adjusting the hardness of the edge of the adsorption film, and controlling the hardness of other areas of the adsorption film to remain unchanged, and combining the ratio of edge adjustment to improve the output pressure actually transmitted to the edge area of ​​the wafer under the condition of constant applied pressure, without changing the grinding parameters or adjusting the structure of the adsorption film, so that the grinding effect of the wafer edge can be improved by more than 14%, and the problem of unstable grinding rate of the wafer edge caused by residues in the initial stage of grinding is avoided, thereby improving the yield of wafer production. The method is simple to operate, low in cost, and has good industrial application prospects. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] In the following embodiments and comparative examples, the chemical mechanical polishing equipment is provided with a polishing head, a polishing pad and a polishing table in order from top to bottom; the structural components of the polishing head include an adsorption film and a retaining ring, and the wafer is located between the adsorption film and the polishing pad; the retaining ring is used to fix the wafer.

[0042] Example 1

[0043] This embodiment provides a method for improving a wafer edge grinding rate, the method comprising:

[0044] The wafer is ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film is reduced by 2SHA, while the hardness of other areas of the adsorption film remains unchanged;

[0045] The hardness of the edge of the adsorption film is 39SHA, and the hardness of other areas is 41SHA; the ratio of the width of the edge of the adsorption film to the radius of the adsorption film is 0.05:1; the thickness of the adsorption film is 0.7mm; the material of the adsorption film includes silica gel; the preparation method of the adsorption film includes: placing the silica gel raw material in a mold and performing pressure molding; during the pressure molding, controlling the temperature of the edge of the mold to be lower than the temperature of other areas of the mold, and the difference between the two is 7°C;

[0046] During the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate; during the grinding, the pressure applied by the grinding head to the wafer is 3.5psi, and the pressure applied to the retaining ring is 5.5psi; during the grinding, the rotation speed of the grinding head is 87r / min, and the rotation speed of the grinding pad is 93r / min.

[0047] Example 2

[0048] This embodiment provides a method for improving a wafer edge grinding rate, the method comprising:

[0049] The wafer was ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film was reduced by 3SHA, while the hardness of other areas of the adsorption film remained unchanged;

[0050] The hardness of the edge of the adsorption film is 39SHA, and the hardness of other areas is 42SHA; the ratio of the width of the edge of the adsorption film to the radius of the adsorption film is 0.04:1; the thickness of the adsorption film is 0.75mm; the material of the adsorption film includes silica gel; the preparation method of the adsorption film includes: placing the silica gel raw material in a mold and performing pressure molding; during the pressure molding, controlling the temperature of the edge of the mold to be lower than the temperature of other areas of the mold, and the difference between the two is 10°C;

[0051] During the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate; during the grinding, the pressure applied by the grinding head to the wafer is 3.2psi, and the pressure applied to the retaining ring is 6psi; during the grinding, the rotation speed of the grinding head is 87r / min, and the rotation speed of the grinding pad is 93r / min.

[0052] Example 3

[0053] This embodiment provides a method for improving a wafer edge grinding rate, the method comprising:

[0054] The wafer was ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film was reduced by 2.5 SHA, while the hardness of other areas of the adsorption film remained unchanged;

[0055] The hardness of the edge of the adsorption film is 38.5SHA, and the hardness of other areas is 41SHA; the ratio of the width of the edge of the adsorption film to the radius of the adsorption film is 0.05:1; the thickness of the adsorption film is 0.8mm; the material of the adsorption film includes silica gel; the preparation method of the adsorption film includes: placing the silica gel raw material in a mold and performing pressure molding; during the pressure molding, controlling the temperature of the edge of the mold to be lower than the temperature of other areas of the mold, and the difference between the two is 8.5°C;

[0056] During the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate; during the grinding, the pressure applied by the grinding head to the wafer is 4psi, and the pressure applied to the retaining ring is 5.2psi; during the grinding, the rotation speed of the grinding head is 87r / min, and the rotation speed of the grinding pad is 93r / min.

[0057] Example 4

[0058] This embodiment provides a method for improving the wafer edge grinding rate, except that the hardness of the edge of the adsorption film is reduced by 4SHA, the hardness of other areas of the adsorption film remains unchanged, the hardness of the edge of the adsorption film is 38SHA, and the hardness of other areas is 42SHA; other conditions are the same as Example 1.

[0059] Example 5

[0060] This embodiment provides a method for improving the wafer edge grinding rate, except that the hardness of the edge of the adsorption film is reduced by 1SHA, the hardness of other areas of the adsorption film remains unchanged, the hardness of the edge of the adsorption film is 39.5SHA, and the hardness of other areas is 40.5SHA; other conditions are the same as Example 1.

[0061] Comparative Example 1

[0062] This comparative example provides a method for improving the wafer edge grinding rate, except that the hardness of the edge of the adsorption film is reduced by 0.5 SHA, the hardness of other areas of the adsorption film remains unchanged, the hardness of the edge of the adsorption film is 40.5 SHA, and the hardness of other areas is 41 SHA; other conditions are the same as Example 1.

[0063] Comparative Example 2

[0064] This comparative example provides a method for improving the wafer edge grinding rate, except that the hardness of the edge of the adsorption film is reduced by 5SHA, the hardness of other areas of the adsorption film remains unchanged, the hardness of the edge of the adsorption film is 36SHA, and the hardness of other areas is 41SHA; other conditions are the same as Example 1.

[0065] Comparative Example 3

[0066] This comparative example provides a method for improving the wafer edge grinding rate, except that the ratio of the width of the adsorption film edge to the radius of the adsorption film is 0.02:1; other conditions are the same as those in Example 1.

[0067] Comparative Example 4

[0068] This comparative example provides a method for improving the wafer edge grinding rate, except that the ratio of the width of the adsorption film edge to the radius of the adsorption film is 0.12:1; other conditions are the same as those in Example 1.

[0069] Comparative Example 5

[0070] This comparative example provides a method for improving the wafer edge grinding rate, except that the hardness of the adsorption film is not adjusted, that is, the hardness of the adsorption film is 41SHA; other conditions are the same as those in Example 1.

[0071] Comparative Example 6

[0072] This comparative example provides a method for improving the wafer edge grinding rate. Except that the hardness of the entire adsorption film is adjusted, that is, the hardness of the adsorption film is 39SHA; other conditions are the same as those in Example 1.

[0073] The methods provided in the above embodiments and comparative examples were used to grind wafers with a diameter of 300 mm, and the grinding rates at the center and edge of the wafer were tested. The results are shown in Table 1.

[0074] Table 1

[0075]

[0076] From Table 1, we can see that:

[0077] (1) The method provided in Examples 1-3 of the present invention grinds the wafer without adjusting the grinding parameters. The grinding rate of the wafer edge is improved without affecting the grinding rate of the wafer center, and the problem of unstable grinding rate of the wafer edge caused by residues in the initial grinding stage is avoided, thereby improving the yield of wafer production; wherein the grinding rate of the wafer edge can be increased by more than 14%;

[0078] (2) It can be seen from the comparison between Example 1 and Examples 4-5 that when the hardness of the edge of the adsorption film decreases slightly lower or slightly higher, although the wafer edge grinding rate can be improved, the improvement effect is less than 10%;

[0079] (3) It can be seen from Example 1 and Comparative Examples 1-2 that if the hardness of the edge of the adsorption film decreases too low, the edge output pressure will not be significantly improved due to the weak transmission pressure, so that the wafer edge grinding rate will not be improved much; if the hardness of the edge of the adsorption film decreases too high, the deformation of the edge of the adsorption film will increase during the grinding process, and the deformation will affect the contact state between the grinding pad and the wafer, making the contact area between the grinding pad and the wafer edge unstable, and thus failing to effectively improve the wafer edge grinding rate;

[0080] (4) Based on Example 1 and Comparative Examples 3-4, it can be seen that if the adjusted adsorption film edge width accounts for too small a proportion, the edge output pressure is not significantly improved due to the weak transmission pressure; if the adjusted adsorption film edge width accounts for too large a proportion, the grinding rate of the non-edge area is affected, resulting in poor grinding uniformity;

[0081] (5) Based on Example 1 and Comparative Example 5, it can be seen that if the hardness of the adsorption film is not adjusted, the output pressure actually transmitted to the edge area of ​​the wafer is too low, resulting in a low edge grinding rate of the wafer during the CMP process. There is also a problem that residues appear in the early stage of grinding, resulting in an unstable edge grinding rate of the wafer, which in turn leads to a decrease in the yield of wafer production;

[0082] (6) Based on Example 1 and Comparative Example 6, it can be seen that if the adsorption film is adjusted as a whole and the hardness of the adsorption film is reduced by 2SHA, although the polishing rate of the wafer edge can be improved, the polishing rate of the wafer center will decrease, and wrinkling of the film will easily occur, thereby reducing the yield of wafer production.

[0083] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for improving wafer edge grinding rate, characterized in that: The method comprises: The wafer is ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film is reduced by 1-4 SHA, while the hardness of other areas of the adsorption film remains unchanged; The ratio of the width of the edge of the adsorption film to the radius of the adsorption film is (0.04-0.07):

1.

2. The method according to claim 1, characterized in that The hardness of the edge of the adsorption film is reduced by 2-3 SHA.

3. The method according to claim 1 or 2, characterized in that: The hardness of the edge of the adsorption film is 37-39.5 SHA; Preferably, the hardness of other regions of the adsorption film is greater than 40 SHA.

4. The method according to any one of claims 1 to 3, characterized in that: The ratio of the width of the edge of the adsorption film to the radius of the adsorption film is (0.04-0.05):

1.

5. The method according to any one of claims 1 to 4, characterized in that: The thickness of the adsorption film is 0.65-0.85 mm; Preferably, the adsorption film is made of silica gel.

6. The method according to any one of claims 1 to 5, characterized in that: The preparation method of the adsorption film comprises: placing a silica gel raw material in a mold and performing pressure molding; Preferably, during the pressure molding, the temperature of the edge of the mold is controlled to be lower than the temperature of other areas of the mold, and the difference between the two is 5-10°C.

7. The method according to any one of claims 1 to 6, characterized in that: The chemical mechanical polishing equipment is provided with a polishing head, a polishing pad and a polishing table in order from top to bottom; the structural components of the polishing head include an adsorption film and a retaining ring, and the wafer is located between the adsorption film and the polishing pad; the retaining ring is used to fix the wafer; Preferably, during the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate.

8. The method according to any one of claims 1 to 7, characterized in that: During the grinding, the grinding head applies a pressure of 3-4 psi to the wafer and a pressure of 5-6 psi to the retaining ring.

9. The method according to any one of claims 1 to 8, characterized in that: During the grinding, the rotation speed of the grinding head is 85-90 r / min, and the rotation speed of the grinding pad is 90-95 r / min.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises: The wafer is ground using chemical mechanical grinding equipment, and the hardness of the edge of the adsorption film is reduced by 1-4 SHA, while the hardness of other areas of the adsorption film remains unchanged; The hardness of the edge of the adsorption film is 37-39.5SHA; the ratio of the width of the edge of the adsorption film to the radius of the adsorption film is (0.04-0.07):1; the thickness of the adsorption film is 0.65-0.85mm; the material of the adsorption film includes silica gel; the preparation method of the adsorption film includes: placing the silica gel raw material in a mold and performing pressure molding; during the pressure molding, controlling the temperature of the edge of the mold to be lower than the temperature of other areas of the mold, and the difference between the two is 5-10°C; The chemical mechanical polishing equipment is provided with a polishing head, a polishing pad and a polishing table in order from top to bottom; the structural components of the polishing head include an adsorption film and a retaining ring, and the wafer is located between the adsorption film and the polishing pad; the retaining ring is used to fix the wafer; During the grinding, the grinding head drives the wafer to rotate, and the grinding table drives the grinding pad to rotate; during the grinding, the pressure applied by the grinding head to the wafer is 3-4psi, and the pressure applied to the retaining ring is 5-6psi; during the grinding, the rotation speed of the grinding head is 85-90r / min, and the rotation speed of the grinding pad is 90-95r / min.

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