Polishing pad and wafer polishing method

Abstract

The invention belongs to the technical field of semiconductor processing, and particularly relates to a polishing pad and a wafer polishing method. The polishing pad comprises a pad body and a silane coating, the pad body is provided with a polishing surface, a plurality of liquid flowing holes are formed in the pad body, and the liquid flowing holes are non-circular holes; and the silane coating is coated on the inner wall of the liquid flowing hole. Polishing liquid can be prevented from remaining on the inner wall of the liquid flowing hole to a certain degree, and the product quality is guaranteed.

Description

Technical Field

[0001] This application belongs to the field of semiconductor processing technology, specifically relating to a polishing pad and a wafer polishing method. Background Technology

[0002] With the continuous development of semiconductor integrated circuit technology, the feature size of devices continues to shrink, and the integration density continues to increase, ushering in the era of nanoscale processes. In order to integrate more transistors and functional units on a single chip, the number of metal interconnect layers is constantly increasing, currently reaching more than ten layers. This trend places extremely stringent requirements on the global planarization of the wafer surface.

[0003] Local planarization techniques such as reverse etching are no longer sufficient to meet the requirements of global planarization. While chemical mechanical polishing (using polishing pads) has become a key technology for solving this problem, it still has significant drawbacks in advanced process applications.

[0004] In particular, when polishing wafers using polishing pads, if polishing fluid remains in the flow holes of the polishing pads, it can cause damage to the wafers during polishing, affecting product quality and becoming a bottleneck restricting the improvement of production yield. Summary of the Invention

[0005] Based on the above-mentioned technical problems, this application provides a polishing pad and a wafer polishing method, which aims to at least partially solve the technical problem of polishing fluid residue in the flow holes of the polishing pad affecting product quality.

[0006] This application is achieved through the following technical solution: In a first aspect of this application, a polishing pad is provided, the polishing pad comprising: a pad body having a polishing surface, the pad body having a plurality of fluid flow holes, the fluid flow holes being non-circular holes; and a silane coating applied to the inner wall of the fluid flow holes.

[0007] The polishing pad provided in this application has multiple non-circular drainage holes on its pad body, which disrupts the adhesion environment of the polishing slurry on the inner wall of the drainage holes. This significantly reduces the tendency of the polishing slurry to remain due to capillary action, thus preventing polishing slurry residue on the inner wall of the drainage holes to a certain extent. In addition, the inner wall of the drainage holes is coated with a silane coating, which forms a hydrophobic layer on the inner wall of the drainage holes, reducing the adsorption force on the inner wall of the drainage holes. The polishing slurry forms water droplets on the inner wall of the drainage holes instead of spreading out. The polishing slurry can be more easily shaken off or washed away by deionized water and vaporized isopropanol, thus significantly reducing residue and preventing wafer breakage during polishing, thereby ensuring product quality.

[0008] In some embodiments, the flow orifice is a frustum-shaped channel.

[0009] In some embodiments, the flow hole has a first end and a second end opposite each other along the axial direction, wherein the first end is located on the polishing surface, the second end is located on the side of the pad facing away from the polishing surface, and the radius of the first end is greater than or less than the radius of the second end.

[0010] In some embodiments, the smaller end of the frustum-shaped channel faces the polished surface, and the taper of the frustum-shaped channel is α, with 60°≤α≤80°.

[0011] In some embodiments, the thickness of the silane coating is h, and 1.25 mm ≤ h ≤ 1.35 mm.

[0012] In some embodiments, the silane coating is made of fluorosilane and aramid fabric.

[0013] In a second aspect of this application, a wafer polishing method is also provided, the polishing method comprising: comparing the downtime of the polishing equipment with a preset time; when the downtime is longer than the preset time, injecting deionized water into the flow holes of the polishing pad described in the first aspect through a conveying device; and when the deionized water injection is completed, conveying vaporized isopropanol into the flow holes of the pad body of the polishing pad through the conveying device.

[0014] In some implementations, the injection time of the deionized water is 2.5 min to 3 min, and the injection flow rate is 5.5 L / min to 6.5 L / min.

[0015] In some implementations, the vaporized isopropanol is delivered at a pressure of 5.5 Bar to 6.5 Bar for a duration of 2.5 min to 3 min.

[0016] In some embodiments, the conveying device includes: a main conveying pipe; and a plurality of conveying branch pipes, each of the conveying branch pipes being configured in a one-to-one correspondence with a plurality of flow holes, one end of each of the plurality of conveying branch pipes being connected to the main conveying pipe, and the other end of each of the plurality of conveying branch pipes being connected to a corresponding flow hole.

[0017] The wafer polishing method provided in this application dilutes the polishing slurry remaining on the inner wall of the flow holes by injecting deionized water into the flow holes of the pad, thereby reducing the concentration of the polishing slurry and using water flow to wash away most of the loosened particles and water-soluble chemicals. Subsequently, vaporized isopropanol is introduced into the flow holes of the pad. Vaporized isopropanol has strong hydrophobicity, which prevents deionized water and polishing slurry from remaining on the inner wall of the flow holes. It can also evaporate quickly and is not easy to remain on the inner wall of the flow holes, thereby ensuring the cleanliness of the inner wall of the flow holes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0019] Figure 1 An exploded view of the polishing pad in one or more embodiments of this application is shown; Figure 2 A schematic flowchart of a wafer polishing method according to one or more embodiments of this application is shown; Figure 3 It shows Figure 2 A schematic diagram of the conveying device configured in the cleaning method shown; Figure 4 A schematic diagram showing the comparison of polishing pad breakage rates before and after the implementation of improvement measures is presented; Figure 5 A schematic diagram comparing the flatness stability before and after implementing the improvement measures is shown.

[0020] Explanation of reference numerals in the attached figures: 10. Polishing pad; 110. Pad; 111. Flow hole; 120. Silane coating; 121. Drain hole; 20. Conveying device; 210. Main conveying pipe; 220. Branch conveying pipe; 230. Pump body; 240. First container; 250. Second container; 260. First valve; 270. Second valve; 280. Conveying pipe. Detailed Implementation

[0021] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0022] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] When polishing wafers using polishing pads, polishing fluid remains in the flow holes of the pads. When the equipment is shut down for a long time, the polishing fluid will remain on the inner wall of the flow holes, forming hard particles such as crystals. During subsequent processing, when the polishing of the next wafer begins, insufficient bonding will occur. These hard particles will act as "scrapers," producing fatal scratches and streaks on the wafer surface, affecting product quality. Furthermore, they may cause damage to the polishing pads, affecting subsequent polishing of the wafers.

[0024] Based on the above-mentioned technical problems, this application provides a polishing pad and a cleaning method thereof, which aims to at least improve the phenomenon of polishing liquid residue in the flow holes of the polishing pad to a certain extent, so as to ensure product quality while avoiding damage to the polishing pad.

[0025] In related technologies, the pad body of polishing pads is mostly made of polyurethane material. Polyurethane material itself contains polar groups and has high surface energy, which makes it easy for polishing fluid to spread and wet its surface. Although this good wettability is beneficial to the distribution of polishing fluid and improves the polishing quality of wafers, it also causes the abrasive generated during wafer polishing to adhere tightly to the flow holes of the polishing pad and be difficult to clean off.

[0026] Based on the above analysis, the polishing pad provided in this application improves the structure to a certain extent to prevent abrasive and polishing fluid from being tightly adhered to the flow holes of the polishing pad. In addition, the improved cleaning method enables the abrasive adhering to the flow holes of the polishing pad to be quickly cleaned.

[0027] In a first aspect of this application, a polishing pad is provided. Figure 1 An exploded view of the polishing pad 10 in one or more embodiments of this application is shown, in conjunction with... Figure 1 The polishing pad 10 includes a pad body 110 and a silane coating 120. The pad body 110 has a polishing surface and a plurality of flow holes 111 are provided on the pad body 110. The flow holes 111 are non-circular holes. The silane coating 120 is coated on the inner wall of the flow holes 111.

[0028] The polishing pad 10 provided in this application has multiple flow holes 111 on its pad body 110. Since the flow holes 111 are non-circular, they can disrupt the adhesion environment of the polishing liquid on the inner wall of the flow holes 111, significantly reducing the tendency of the polishing liquid to remain due to capillary action. This can, to a certain extent, prevent the polishing liquid from remaining on the inner wall of the flow holes 111. In addition, since the inner wall of the flow holes 111 is coated with a silane coating 120, the silane coating 120 can form a hydrophobic layer on the inner wall of the flow holes 111, thereby reducing the adsorption force on the inner wall of the flow holes 111. The polishing liquid forms water droplets on the inner wall of the flow holes 111 instead of spreading out. The polishing liquid can be more easily shaken off or washed away by deionized water and vaporized isopropanol, thereby significantly reducing residue and thus preventing the wafer from being damaged during polishing, ensuring product quality.

[0029] In some embodiments, the pad body 110 of the polishing pad 10 provided in this application can rotate, and it rotates in the opposite direction to the wafer at a certain speed. The polishing liquid is sprayed onto the polishing surface of the polishing pad 10, and the chemical components in the polishing liquid react chemically with the wafer surface to soften the target material. The softened target material is removed by the mechanical force generated by the relative motion, and finally the wafer achieves atomic-level flatness.

[0030] In some embodiments, the flow hole 111 extends through the thickness direction of the pad 110 and has a first end and a second end opposite to each other along the axial direction. The first end is located at the end of the pad 110 facing the polishing surface, and the second end is located at the end of the pad 110 facing away from the polishing surface. Polishing liquid is delivered from the second end of the flow hole 111 into the flow hole 111 and flows out from the first end of the flow hole 111 onto the polishing surface of the pad 110.

[0031] In related technologies, the flow hole 111 is mostly cylindrical. Within a cylindrical cavity, meaning the inner diameters of both ends of the flow hole 111 are the same, the surface tension of the liquid minimizes its surface area, allowing the liquid to form a stable and complete "mensular surface." This surface has a large surface area. If the hole diameter is very small (similar to a capillary), the surface tension generates a strong "capillary adhesion force." This force resists forces such as gravity and centrifugal force that attempt to expel the liquid, causing it to be "locked" inside the flow hole 111. Even with the high-speed rotation of the polishing pad 10, some liquid may still remain on the sidewall of the flow hole 111. However, this application sets the flow hole 111 to be non-circular, thus making the diameter of the flow hole 111 variable, preventing the liquid from forming a stable and uniform mensular surface. This instability makes it harder for the liquid to "cling," allowing it to be flung out of the flow hole 111 when the polishing pad 10 rotates at high speed, thereby preventing liquid residue within the flow hole 111 to some extent.

[0032] In some embodiments, the flow hole 111 is a frustum-shaped channel, that is, the cross-section of the flow hole 111 is trapezoidal, the diameters of the first and second ends of the flow hole 111 are different, and the diameter of the inner wall of the flow hole 111 is continuously changing, thereby forming an inclined surface on the inner wall of the flow hole 111. Under the condition of high-speed rotation of the polishing pad 10, the liquid in the flow hole 111 is more likely to flow out completely, reducing eddies and thus reducing the residue of polishing liquid in the flow hole 111. Therefore, by designing the flow hole 111 as a frustum-shaped channel, this application significantly reduces the tendency of polishing liquid to remain due to capillary action by disrupting the stable adhesion environment of the liquid surface tension.

[0033] In some embodiments, the radius of the first end of the flow hole 111 is smaller than the radius of the second end, that is, the larger opening of the flow hole 111 faces the wafer. Under the action of centrifugal force, the waste liquid can be more smoothly "thrown out" along the inclined wall, reducing the retention in the hole and facilitating the discharge of polishing fluid and grinding debris. For example, the smaller end of the frustum-shaped channel faces the polishing surface, that is, the first end of the flow hole 111 faces the polishing surface. The taper of the frustum-shaped channel (i.e., the flow hole 111) can be α, and α satisfies: 60°≤α≤80°. For example, α can be 60°, 65°, 70°, 75°, 80° and any value between the two. The reason for this setting is that if α is too small, the inner wall of the flow hole 111 will be too vertical, which may cause the silane coating 120 mentioned below to fall off. If α is too large, the inner wall of the flow hole 111 will be too horizontal, which may cause air bubbles to exist between the pad 110 and the silane coating 120 mentioned below, and the air bubbles may not be able to be discharged.

[0034] In some other embodiments, the radius of the first end of the flow hole 111 is greater than the radius of the second end, that is, the larger opening of the flow hole 111 faces the wafer, and the flow hole 111 forms a "nozzle" looking upward, which produces a converging and accelerating effect on the polishing slurry, so that the polishing slurry is delivered more concentratedly and powerfully to the contact area between the wafer and the polishing pad 10, in order to help obtain a more sufficient supply of polishing slurry in the central area of ​​the wafer.

[0035] It should be noted that in other embodiments, the inner wall of the flow hole 111 can also be curved, which can also achieve the above effect.

[0036] As described above, the pad body 110 of the polishing pad 10 is mostly made of polyurethane material, which forms a hydrophilic layer on the inner wall of the flow hole 111. Polishing fluid easily remains on the inner wall of the flow hole 111. However, this application coats the inner wall of the flow hole 111 with a silane coating 120, thereby forming a hydrophobic layer on the inner wall of the flow hole 111. On this surface, the polishing fluid tends to form water droplets rather than spread out. Due to the greatly reduced adhesion, under the centrifugal force of the high-speed rotation of the polishing pad 10 and the impact of subsequent rinsing, these droplets and the abrasive particles therein are more easily thrown out or washed away, thus significantly reducing residue.

[0037] In some embodiments, after the pad body 110 of the polishing pad 10 is attached, a silane coating 120 can be applied to the fluid outlet 111 of the pad body 110. The coating thickness is h, and h satisfies: 1.25mm ≤ h ≤ 1.35mm. Exemplarily, h can be 1.25mm, 1.30mm, 1.35mm, or any value between the two.

[0038] In addition, a silane coating 120 is adapted to be coated on the inner wall of the flow hole 111. That is, the silane coating 120 is also frustum-shaped, and its thickness is consistent with the thickness of the pad 110. Furthermore, a drainage hole 121 is formed in the middle of the silane coating 120. The drainage hole 121 is a circular hole with a diameter of d, and d satisfies: 4mm≤d≤6mm. For example, d can be 4mm, 4.5mm, 5mm, 5.5mm, 6mm or any value between the two above, so as to allow the polishing fluid to flow out normally.

[0039] This application sets the flow hole 111 in a frustum shape, so that the cross section of the inner wall of the flow hole 111 is trapezoidal. The trapezoidal cross section of the inner wall can increase the air flow, reduce the probability of air bubbles between the two materials 110 and silane coating 120, and generate a self-locking / wedge effect, reducing the risk of silane coating 120 falling off.

[0040] In practice, the silane coating 120 is made of fluorosilane and aramid fabric, and it can be applied to the inner wall of the flow hole 111 by solution immersion and / or vapor deposition. The silane coating does not introduce impurities such as metals, can isolate the polishing fluid, and does not affect the flatness of the product.

[0041] Based on the polishing pad 10 described in the first aspect, in a second aspect of this application, this application also provides a method for polishing a wafer. Figure 2 This application illustrates a schematic flowchart of a wafer polishing method according to one or more embodiments, in conjunction with... Figure 2 The polishing method includes: S1: Compare the downtime of the polishing equipment with the preset downtime, and confirm whether the downtime is longer than the preset downtime; S2: When the downtime exceeds the preset time, deionized water is injected into the liquid flow hole 111 of the pad body 110 of the polishing pad 100 through the conveying device. S3: At the end of the deionized water injection, vaporized isopropanol is delivered to the flow hole 111 of the pad body 110 of the polishing pad 100 through the delivery device.

[0042] The cleaning method for the polishing pad 10 provided in this application first involves injecting deionized water into the flow holes 111 of the pad body 110 to dilute the residual polishing liquid, reduce the concentration of the polishing liquid, and use water flow to wash away most of the loosened particles and water-soluble chemicals; then, vaporized isopropanol is supplied into the flow holes 111 of the pad body 110. Vaporized isopropanol has strong hydrophobicity, which prevents deionized water and polishing liquid from remaining on the inner wall of the flow holes 111, and it can evaporate quickly, so it is not easy to remain on the inner wall of the flow holes 111, thus ensuring the cleanliness of the inner wall of the flow holes 111.

[0043] Combination Figure 2 The wafer polishing method provided in this application compares the downtime of the polishing equipment with the preset time before injecting deionized water into the flow hole 111 of the pad 110. If the downtime exceeds the preset time, the inner wall of the flow hole 111 is cleaned. If the downtime is less than the preset time, the polishing equipment performs the normal polishing process.

[0044] This is because the polishing slurry needs a certain amount of time to crystallize within the flow hole 111. If the polishing slurry has not yet crystallized within the set time, and the polishing equipment continues to operate within this set time, the polishing slurry will not have crystallized on the inner wall of the flow hole 111, thus not affecting the polishing of the wafer, and correspondingly, there is no need to clean the inner wall of the flow hole 111. For example, this preset time can be 10 minutes. If the polishing equipment is stopped for more than 10 minutes, the cleaning procedure for the inner wall of the flow hole 111 will be initiated.

[0045] In some embodiments, injecting deionized water into the flow hole 111 of the pad 110 specifically includes: the injection time of deionized water is 2.5 min to 3 min, and the injection flow rate is 5.5 L / min to 6.5 L / min.

[0046] In some embodiments, the delivery of vaporized isopropanol to the flow hole 111 of the pad 110 specifically includes: the delivery pressure of the vaporized isopropanol is 5.5 Bar-6.5 Bar, and the delivery time is 2.5 min-3 min, so that the vaporized isopropanol can be sprayed at high pressure onto the inner wall of the flow hole 111. Compared with nitrogen, vaporized isopropanol has a strong hydrophobic effect and can play a role in preventing water from entering the surface, isolating water and residual polishing liquid, and preventing polishing liquid and deionized water from remaining on the inner wall of the flow hole 111.

[0047] Figure 3 It shows Figure 2 A schematic diagram of the conveying device configured in the cleaning method shown. (Combined with...) Figure 3 In some embodiments, deionized water and vaporized isopropanol share a common conveying device 20, which includes a main conveying pipe 210 and multiple conveying branch pipes 220. Each conveying branch pipe 220 is provided with a corresponding flow hole 111. One end of each of the multiple conveying branch pipes 220 is connected to the main conveying pipe 210, and the other end of each of the multiple conveying branch pipes 220 is connected to the corresponding flow hole 111. In specific implementation, the main delivery pipe 210 is connected to the pump body. The first container 240 for storing deionized water and the second container 250 for storing vaporized isopropanol are both connected to the pump body 230. A first valve 260 is provided between the first container 240 and the pump body 230, and a second valve 270 is provided between the second container 250 and the pump body 230. That is, by controlling the opening of the first valve 260 and the second valve 270 respectively, deionized water and vaporized isopropanol can be sequentially delivered to the main delivery pipe 210 through the pump body 230, and then delivered to the corresponding flow hole 111 through the delivery branch pipe 220 to clean the inner wall of the corresponding flow hole 111.

[0048] Combination Figure 3 In some embodiments, the delivery pipe 280 for supplying polishing slurry to the flow orifice 111 is also connected to the main delivery pipe 210. That is, the delivery of polishing slurry, as well as deionized water and vaporized isopropanol, can be delivered to the corresponding flow orifice 111 through the main delivery pipe 210 and the branch delivery pipe 220. This arrangement can reduce the space occupied by the equipment to a certain extent and save costs.

[0049] Combination Figure 3 In some embodiments, the direction of delivery of the polishing slurry is opposite to that of delivery of deionized water and vaporized isopropanol. The reason for this arrangement is that the polishing slurry can flow into the polishing pad 10 through the pipeline delivery pipe 280, while the vaporized isopropanol and deionized water cannot flow to the polishing pad 10 due to temperature and chemical composition.

[0050] Furthermore, during the polishing process, when polishing a wafer on both sides, the polishing equipment needs to work on both sides of the silicon wafer. This polishing generates stress on both sides of the wafer, which is transmitted through the thickness of the wafer and coupled within the wafer to achieve a balance. If the polishing equipment does not work on either side of the wafer, i.e., only on the front or back side, the uniformity of the back side processing changes after the polishing pad 10 is damaged, disrupting the balance and causing the wafer to deviate from its ideal flatness. This leads to a deterioration in the front side ZDD (Z-axis Double Derivative). After the polishing pad 10 is damaged, the polishing fluid accumulates locally, affecting the uneven stress distribution and local flatness deterioration. The deterioration of the back side flatness affects the flatness measurement equipment's calculation of the reference plane, thus affecting the measurement of the front side ZDD.

[0051] Figure 4 A schematic diagram comparing the polishing pad breakage rate before and after the implementation of the improvement measures is shown. Figure 5 A schematic diagram comparing the flatness stability before and after implementing the improvement measures is shown. Figure 4 as well as Figure 5 It can be seen that after implementing the above measures, the breakage rate of the polishing pad is significantly reduced and the flatness stability is improved.

[0052] In summary, the polishing pad 10 provided in this application, by designing the flow holes 111 of the polishing pad 10 as non-circular holes and coating the inner wall of the flow holes 111 with a silane coating 120, can to a certain extent prevent abrasive and polishing fluid from tightly adhering to the flow holes 111 of the polishing pad 10. In addition, by sequentially supplying deionized water and vaporized isopropanol to the flow holes 111, the polishing fluid remaining on the inner wall of the flow holes 111 can be cleaned to ensure the cleanliness of the inner wall of the flow holes 111, thereby ensuring wafer quality and preventing the polishing pad 10 from being damaged, which would affect the subsequent polishing of the wafer. It has good practicality.

[0053] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0054] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0055] In this application, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0056] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0057] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A polishing pad, characterized by, The polishing pad comprises: a pad body having a polishing surface, the pad body being provided with a plurality of flow liquid holes, the flow liquid holes being non-circular holes; a silane coating layer coated on inner walls of the flow liquid holes.

2. The polishing pad of claim 1, wherein The flow liquid holes are frustoconical channels.

3. The polishing pad of claim 2, wherein, The flow liquid holes have opposite first and second ends in the axial direction, wherein the first end is located at the polishing surface, and the second end is located at a side of the pad body opposite to the polishing surface, and the first end has a radius greater than or less than that of the second end.

4. The polishing pad of claim 3, wherein, The smaller end of the frustoconical channel faces the polishing surface, the taper of the frustoconical channel is α, and 60°≤α≤80°.

5. The polishing pad of any of claims 1-4, wherein, The thickness of the silane coating layer is h, and 1.25mm≤h≤1.35mm.

6. The polishing pad of any of claims 1-4, wherein, The silane coating layer is made of fluorosilane and aramid fabric.

7. A wafer polishing method characterized by, The polishing method comprises: comparing the downtime of the polishing equipment with a preset duration; when the downtime is greater than the preset duration, injecting deionized water into the flow liquid holes of the polishing pad of any one of claims 1-4 through a conveying device; when the injection of deionized water is completed, conveying vaporized isopropyl alcohol to the flow liquid holes of the pad body of the polishing pad through the conveying device.

8. The wafer polishing method according to claim 7, wherein The injection duration of the deionized water is 2.5min-3min, and the injection flow rate is 5.5L / min-6.5L / min.

9. The wafer polishing method of claim 7, wherein The conveying pressure of the vaporized isopropyl alcohol is 5.5Bar-6.5Bar, and the conveying duration is 2.5min-3min.

10. The wafer polishing method according to any one of claims 7 to 9, wherein The conveying device comprises: a conveying main pipe; and a plurality of conveying branch pipes, each of the conveying branch pipes being provided in one-to-one correspondence with a plurality of the flow liquid holes, one end of each of the plurality of conveying branch pipes being connected to the conveying main pipe, and the other end of each of the plurality of conveying branch pipes being connected to a corresponding one of the flow liquid holes.

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