Polishing pad, manufacturing method therefor and use thereof

Abstract

Provided in the present invention are a polishing pad, a manufacturing method therefor and the use thereof. The polishing pad comprises a base material and a resin layer attached to the base material, the raw material components of the resin layer comprising a resin and a pore-forming agent, and the resin comprising a modified polyethersulfone resin and a polyurethane resin. The present application uses the modified polyethersulfone resin as a polishing pad resin, which greatly improves the oxidation resistance of polishing pads, thereby further improving the service life of polishing pads for polishing SiC substrates, and improving the durability.

Description

A polishing pad and its preparation method and use TECHNICAL FIELD The present application relates to the field of CMP material preparation in silicon carbide substrate processing, in particular to a polishing pad and its preparation method and use. BACKGROUND As the third generation of wide band gap semiconductor material, silicon carbide (SiC) has the characteristics of large band gap, high thermal conductivity, high critical breakdown field strength, and high electron saturation drift rate, which can effectively break through the physical limit of traditional silicon-based semiconductor devices and materials, and develop a new generation of semiconductor devices that are more suitable for high voltage, high temperature, high power, and high frequency conditions. SiC is the third hardest material in the world, not only has the characteristics of high hardness, but also has high brittleness and low fracture toughness, which makes it easy to cause brittle fracture of the material during grinding and polishing, leaving a surface fracture layer on the material surface and causing serious surface and subsurface damage, affecting the processing precision. The high processing difficulty of silicon carbide in cutting, grinding and polishing mainly lies in: (1) high hardness, Mohs hardness distribution is 9.2-9.6; (2) high chemical stability, almost no reaction with any strong acid or strong base; (3) immature processing equipment. The substrate processing procedure is very complicated, and the low-efficiency and complex processing technology leads to a serious shortage of production capacity and output. In order to realize high removal and planarization of silicon carbide substrate, the current double-sided CMP process of silicon carbide substrate uses non-woven polishing pad combined with potassium permanganate polishing liquid. However, potassium permanganate is a strong oxidizing agent, which can corrode the polyurethane coating of the non-woven polishing pad, causing the polyurethane impregnated on the non-woven fabric to easily fall off during high-pressure and high-speed CMP process, resulting in the non-woven polishing pad being hairy, the fibers falling off and blocking the filter screen, and the polishing removal rate decreasing. The invention patent CN200880003811 uses a bundle of fibers, by bundling the ultra-fine single fibers constituting the fiber bundle to exist in the state of a thick fiber, a polishing pad with high rigidity can be obtained. The patent CN108349062 weaves the warp and weft of the raw material fibers, modifies the raw material, enhances the toughness and strength of the non-woven fabric, and thus improves the hardness of the final product. In the patent CN201480007963, a secondary impregnation method is adopted, a softer polyurethane resin is impregnated first, and after solidification, another kind of resin is impregnated, which can be cured and cross-linked, and the performance of the final product can also be improved. The invention patent JP2012101333A discloses a preparation process of a polishing pad, which adopts a wet coating process to coat a resin layer on a plastic film, improves the mechanical strength of the final product by mixing two kinds of resins with different hardness, and improves the pore structure by wet solidification. However, after the product prepared by this method is oxidized, the molecular bond of the resin film is broken, and the resin film on the surface of the product is easy to crack, thereby affecting the polishing effect. The above method is complicated in process and operation, and only the mechanical performance of the polishing pad is improved, which can improve the polishing efficiency to a certain extent, but the polishing pad still has the defect of poor durability due to the influence of the strong oxidizing agent in the polishing liquid. SUMMARY In view of the above-mentioned defects of the prior art, the purpose of the present application is to provide a polishing pad and a preparation method and use thereof, which are used to solve the problems in the prior art. To achieve the above-mentioned purpose and other related purposes, the present application is obtained by the following technical scheme. The present application discloses a polishing pad, comprising a base material, wherein the base material is impregnated with a resin material, and the raw material components of the resin material comprise resin and pore-forming agent; the resin comprises modified polyether sulfone resin and polyurethane resin. Preferably, the polyurethane resin accounts for 10-30% of the mass of the resin. For example, it can be 10-20%, 20-30%. The more the amount of polyurethane resin, the better the toughness and the worse the oxidation resistance of the polishing pad. Preferably, the modified polyether sulfone resin accounts for 70-90% of the mass of the resin. For example, it can be 70-80%, 80-90%. Preferably, the pore-forming agent accounts for 0.3-1% of the mass of the resin. For example, it can be 0.3-0.5%, 0.5-0.8%, 0.8-1.0%. The more the amount of pore-forming agent, the better the air permeability, the worse the oxidation resistance and the better the toughness of the polishing pad. The more the amount of resin, the worse the air permeability, the better the oxidation resistance and the worse the toughness of the polishing pad. Preferably, the pore-forming agent is selected from polyacrylic acid and / or polyvinyl alcohol. More preferably, the weight average molecular weight of the polyacrylic acid is 20000-60000. For example, it can be 20000-30000, 30000-40000, 40000-50000, 50000-60000. More preferably, the weight average molecular weight of the polyvinyl alcohol is 50000-100000. For example, it can be 50000-75000, 75000-80000, 80000-90000, 00000-100000. Preferably, the modified polyether sulfone resin is obtained by grafting reaction of acrylic acid and polyether sulfone. More preferably, the mass ratio of the polyether sulfone to the acrylic acid is 10:(0.1-1). For example, it can be 10:(0.1-0.3), 10:(0.3-0.5), 10:(0.5-0.7), 10:(0.7-1). Preferably, the polyether sulfone resin has a weight average molecular weight of 10,000-70,000. For example, it can be 10,000-20,000, 20,000-30,000, 30,000-40,000, 40,000-50,000, 50,000-60,000, 60,000-70,000, more preferably 30,000-50,000. Preferably, the polyurethane resin has a 100% modulus of 1-15 MPa. For example, it can be 1-5 MPa, 5-7 MPa, 7-10 MPa, 10-15 MPa. Preferably, the raw material component further comprises a first solvent selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide. Preferably, the base material is selected from one of a fabric, a non-woven fabric or a woven fabric. The resin material is filled between the fibers of the base material, and after oxidation, even if the molecular bonds of the resin material are broken, it will not cause the polishing pad to crack, thereby affecting the polishing effect. More preferably, the fiber raw material of the non-woven fabric comprises one or more of polypropylene, polyester, nylon, viscose, acrylic, ethylene, chlorofiber, polyester fiber and polyamide fiber. Preferably, the fiber fineness of the fiber raw material of the base material is 2.6-3.0 denier. Preferably, the polishing pad comprises one or more of the following characteristics: a) a density of 0.4-0.5 g / cm 3 ; b) a Shore A hardness of 80-91 HA; c) a compression rate of 2.0-4.0%; d) a compression elasticity rate of 60-75%; e) an air permeability of not less than 100 m 2 / s; f) after immersion in an alkaline potassium permanganate solution with a concentration of 4.5-5.5% and a pH of 8.5-9.5, the wear amount is not higher than 100 mg under the following conditions: using an H-18 ceramic grinding wheel with a load of 1-2 kg weight, rotating at a speed of 60-75 rpm for 500-600 revolutions. For example, the air permeability of the polishing pad can be 102 m 2 / s, 110 m 2 / s, 185 m 2 / s, 191 m 2 / s, 233 m 2 / s. For example, the wear amount of the polishing pad can be 41 mg, 57 mg, 61 mg, 67 mg. The present application also discloses a preparation method of the polishing pad as described above, comprising the following steps: 1) mixing the raw material components to form a homogeneous impregnation solution; 2) treating the base material in the impregnating solution, and then putting it into a coagulation solution to obtain the polishing pad. Preferably, the content of the modified polyether sulfone resin in the impregnating solution is 15-25wt%. For example, it can be 15-16wt%, 16-18.3wt%, 18.3-19.2wt%, 19.2-20wt%, 20-23.5wt%, 23.5-25wt%. Preferably, the content of the polyurethane resin in the impregnating solution is 2-10wt%. For example, it can be 2-2.6wt%, 2.6-4wt%, 4-4.8wt%, 4.8-7.8wt%, 7.8-10wt%. Preferably, the content of the pore-forming agent in the impregnating solution is 0.1-0.2wt%. Preferably, the modified polyether sulfone resin is dried before use, and the drying temperature is 110-130℃. Preferably, the base material is dried before the impregnating treatment, and the drying temperature is 90-120℃. Preferably, the impregnating solution is vacuum degassed before the impregnating treatment. Preferably, the impregnated base material is further subjected to a rolling treatment. More preferably, the rolling speed is 1-5r / min, and the rolling pressure is 0.1-1.0Mpa. Preferably, the coagulation solution is an aqueous solution of N,N-dimethylformamide. More preferably, the content of the N,N-dimethylformamide in the coagulation solution is 17-22wt%. For example, it can be 15-20wt%, 20-25wt%. Preferably, the coagulation-treated base material is further subjected to one or more of the following treatments: water washing, drying, polishing, and grooving. More preferably, the drying temperature is 120-130℃, and the drying time is 2-3h. For example, the drying temperature can be 100-110℃, 110-120℃, 120-130℃, 130-140℃, 140-150℃. More preferably, the polishing is performed by polishing both sides of the polishing pad with sandpaper having a mesh number of 170-200. Preferably, the thickness of the base material is 1.8-2.2mm, and the gram weight is 270-330g / cm 2 . The application also discloses the use of the polishing pad as described above as a polishing pad for polishing silicon carbide substrates in chemical mechanical polishing. The application discloses a polishing pad and a preparation method and application thereof, and has the following beneficial effects: The modified polyether sulfone resin is used as the polishing pad resin, the oxidation resistance of the polishing pad is greatly improved, the service life of the polishing pad for polishing SiC substrates is improved, and the durability is improved; a certain amount of low-modulus polyurethane resin is added in the modified polyether sulfone resin, the toughness of the polishing pad is improved while the oxidation resistance is ensured, and the polishing pad has a certain resilience; and a small amount of pore-forming agent is added to improve the porosity of the polishing pad. The prepared polishing pad has good oxidation resistance, air permeability and toughness through specific proportioning of the components, the polishing rate and the substrate surface quality are both good when the polishing pad is used for polishing SiC substrates, and the service life of the polishing pad is also improved. The preparation method is simple, only one step of immersion and solidification is needed, no additional process is needed, the production efficiency is high, the cost is low, and the method is suitable for industrial large-scale production. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 shows the test effect diagram of the polishing rate of the polishing pads prepared in Example 3 and Comparative Examples 1-3 and 8 of the application and a commercially available polishing pad suba800. Fig. 2 shows the test effect diagram of the scratch number of the polishing pads prepared in Example 3 and Comparative Examples 1-3 and 8 of the application and a commercially available polishing pad suba800. Fig. 3 shows the test effect diagram of the polishing rate of the polishing pads prepared in Example 1 and Comparative Examples 4-5 of the application. Fig. 4 shows the test effect diagram of the scratch number of the polishing pads prepared in Example 1 and Comparative Examples 4-5 of the application. Fig. 5 shows the test effect diagram of the polishing rate of the polishing pads prepared in Example 3 and Comparative Examples 6-7 of the application. Fig. 6 shows the test effect diagram of the scratch number of the polishing pads prepared in Example 3 and Comparative Examples 6-7 of the application. Fig. 7 shows the surface effect diagram of the polishing pad prepared in Example 3 of the application after the oxidation resistance test. Fig. 8 shows the surface effect diagram of the polishing pad prepared in Comparative Example 1 of the application after the oxidation resistance test. Fig. 9 shows the surface effect diagram of the polishing pad prepared in Comparative Example 7 of the application after the oxidation resistance test. Fig. 10 shows the surface effect diagram of the polishing pad prepared in Example 3 of the application after the 20h polishing rate test. Fig. 11 shows the surface effect diagram of the polishing pad prepared in Comparative Example 1 of the application after the 20h polishing rate test. Fig. 12 shows the surface effect diagram of the polishing pad prepared in Comparative Example 7 of the application after the 20h polishing rate test. DETAILED DESCRIPTION The present application will be described in further detail by the following specific examples, and other advantages and effects of the present application will be more clearly understood from the description. Before further description of the present application, it is understood that the present application is not limited to the particular examples described herein, which are presented for purposes of illustration and not limitation. It is also understood that the terminology used in the ensuing description is for the purpose of describing the particular examples only and is not intended to limit the scope of the present application. 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. Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of the present application, unless specifically stated otherwise. 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. Any methods, devices and materials similar or equivalent to those described herein can be used in the practice of the present application, unless specifically stated otherwise. When a numerical range is given in the examples, it is understood that, unless otherwise stated by the present application, each numerical range has two endpoints and any number between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, devices, materials used in the examples, any method, device and material of the prior art similar or equivalent to those described in the examples of the present application can also be used to implement the present application according to the prior art mastered by those skilled in the art and the description of the present application. The modified polyether sulfone resin in the present application is prepared by the following method: The pretreated polyether sulfone is dissolved in a second solvent, and then an acrylic monomer is added. The homogeneous solution is stirred at 60-80°C. The homogeneous solution is irradiated under a radiation source in an oxygen-free atmosphere. The irradiation reaction temperature is 10-30°C, the irradiation dose rate is 0.5-5 kGy / h, and the total irradiation dose is 5-30 kGy. After the reaction is completed, the homogeneous solution is precipitated in an aqueous solution, washed repeatedly, soaked in water for 20-30 h, and vacuum dried. Specifically, the pretreatment method of the polyether sulfone resin is as follows: the polyether sulfone resin is washed in water and soaked for more than one week, with water changed multiple times, and then dried under vacuum at 70-80°C until the weight is constant. Specifically, the second solvent is selected from one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide and dimethyl sulfoxide. Specifically, the mass ratio of the polyether sulfone to the acrylic monomer is 10:(0.1-1). Specifically, the amount of the polyether sulfone in the homogeneous solution is 5-20 wt%. Specifically, the radiation source is generally a γ-ray radiation source, preferably 60 C O . Specifically, the oxygen-free atmosphere can be achieved by introducing nitrogen and / or inert gas to remove oxygen. The embodiment of the present application further provides a preparation method of a specific polishing pad, and the preparation steps are as follows: (1) Preparation of the impregnation solution: A certain amount of modified polyether sulfone resin powder is weighed, dried in an oven at 110-130°C for 12-24h to remove possible residual moisture, DMF is added, and a high-speed shearing dispersion machine is used to stir and disperse for 30-45min to fully dissolve the modified polyether sulfone resin powder to form solution A, and the solid content is 20-35wt%. The weight average molecular weight of the modified polyether sulfone powder is 10000-70000. A certain amount of polyurethane resin solution is weighed, DMF is added, and a high-speed stirring machine is used to stir and disperse for 30-45min to form solution B, and the solid content is controlled at 20-35wt%. The 100% modulus of the polyurethane resin is 1-15Mpa. A certain amount of pore-forming agent is weighed and added to the first solvent DMF, and high-speed stirring and dispersion are performed for 30-45min to obtain solution C, and the solid content is 1-5wt%. The pore-forming agent is selected from polyacrylic acid and / or polyvinyl alcohol. The three solutions A, B and C are mixed in a mass ratio of 60-80:10-30:10-30, and after stirring and degassing, the impregnation solution is formed and is ready for use after standing. (2) Wet forming of the polishing pad: The non-woven fabric base cloth is pretreated in an oven at 100-150°C for 1-2h to remove moisture, then the non-woven fabric base cloth is immersed in the impregnation solution, and a pressure roller is used to extrude the excess floating material on the surface. The non-woven fabric base cloth is immersed in a coagulation solution to make the resin coagulate on the non-woven fabric fibers. After washing, the polishing pad semi-finished product is obtained by drying at 120-130°C for 2-3h. The coagulation solution is an aqueous solution of N,N-dimethylformamide with a concentration of 15-25wt%. The non-woven fabric is made of short fibers by needle punching process, and the fiber raw material is selected from one of propylene, polyester, nylon, viscose fiber, acrylic, ethylene, chloroform, polyester, and polyamide. The fiber fineness of the fiber raw material is 2.6-3.0 denier. The thickness of the non-woven fabric is 1.8-2.2mm, and the grammage is 270-330g / cm 2 .. (3) Processing of the polishing pad: Both sides of the polishing pad semi-finished product are polished, the grit number of the sandpaper is 170-200, and the thickness of the product is controlled at 1-1.5mm. Then one side is attached with double-sided adhesive tape, and the other side is subjected to slotting treatment. The polishing pad finished product is obtained after the above steps. More specific examples are provided below, and the reagents and instruments used in the following examples are all conventional reagents and can be purchased from the market, and the specific details are as follows: Polyurethane resin solution, purchased from Asahi Chemical, concentration of 35wt%. Prepared from polyester polyol and MDI (diphenylmethane diisocyanate). The first solvent is DMF. In the following examples, the weight average molecular weight of polyacrylic acid is 40000, and the weight average molecular weight of polyvinyl alcohol is 75000. Example 1 This example provides a specific method for preparing a polishing pad, and the preparation steps are as follows: (1) Preparation of modified polyether sulfone resin: weigh 10 g of pretreated polyether sulfone powder, dissolve in 86 g of DMF solvent, add 1 g of acrylic monomer, stir at a temperature of 60°C for 24 h to obtain a homogeneous solution; after continuously passing N2 for 15 min, the homogeneous solution is placed in a 60°C water bath for 24 h to complete the reaction. 60 C O Under the source, irradiation reaction is carried out at 20°C, the irradiation dose rate is 1 kGy / h, and the absorbed dose is 17 kGy. After the irradiation reaction is completed, the homogeneous solution is reversed phase precipitated in an aqueous solution, repeatedly washed for multiple times, soaked in deionized water for 24 h, and dried in a vacuum drying oven (80°C) to constant weight. (2) Preparation of impregnating solution: Weigh a certain amount of modified polyether sulfone resin powder, add DMF, and use a high-speed shearing disperser to stir for 30 min to fully dissolve and form solution A, with a solid content of 30% wt. The weight average molecular weight of the polyether sulfone powder is 50000. Weigh a certain amount of polyurethane resin solution, add DMF, and use a high-speed stirring machine to stir and disperse for 30 min to form solution B, with a solid content controlled at 30% wt. The 100% modulus of the polyurethane resin is 7 MPa. Weigh a certain amount of polyacrylic acid, add to the first solvent DMF, and high-speed stir and disperse for 30 min to obtain solution C, with a solid content of 1% wt. Mix A, B, and C three solutions according to the mass ratio of 90:10:15, stir and degas to form an impregnating solution, and stand by. In the impregnating solution, the polyurethane resin accounts for 10% of the mass of the resin, the polyacrylic acid accounts for 0.5% of the mass of the resin, the content of the modified polyether sulfone resin in the impregnating solution is 23.5 wt%, the content of the polyurethane resin in the impregnating solution is 2.6 wt%, and the content of the pore-forming agent in the impregnating solution is 0.1 wt%. (3) Wet forming of polishing pad: The non-woven fabric base cloth is pre-treated in an oven at 100°C for 2 h to remove water, then the non-woven fabric base cloth is immersed in the impregnating solution, and the excess floating material on the surface is squeezed out by a pressure roller. The non-woven fabric base cloth is immersed in a coagulating solution to make the impregnating solution coagulate on the non-woven fabric fibers. After washing, dry at 120°C for 2 h to obtain a polishing pad semi-finished product. The coagulation liquid is an aqueous solution of N,N-dimethylformamide, and the concentration of N,N-dimethylformamide is 20wt%. The non-woven fabric is made of short fibers by needle punching process, and the fiber raw material is selected from polyester short fibers with a fiber fineness of 3 deniers. The thickness of the non-woven fabric is 2mm, and the grammage is 300g / m 2 . (4) Processing of the polishing pad: Both sides of the polishing pad semi-finished product are polished, the sandpaper mesh is 180 mesh, and the thickness of the product is controlled at 1.3mm. Then one side is attached with double-sided adhesive tape, and the other side is subjected to slotting treatment. After completion, the polishing pad finished product is obtained. Example 2 The present embodiment provides a specific method for preparing a polishing pad, and the preparation steps are basically the same as those of Example 1, except that: In step (2), the pore-forming agent is polyvinyl alcohol, and the three solutions A, B and C are mixed in a mass ratio of 70:30:15. In the impregnating solution, the polyurethane resin accounts for 30% of the mass of the resin, the polyvinyl alcohol accounts for 0.5% of the mass of the resin, the content of the modified polyether sulfone resin in the impregnating solution is 18.3wt%, the content of the polyurethane resin in the impregnating solution is 7.8wt%, and the content of the pore-forming agent in the impregnating solution is 0.1wt%. Example 3 The present embodiment provides a specific method for preparing a polishing pad, and the preparation steps are basically the same as those of Example 1, except that: In step (2), the molecular weight of the modified polyether sulfone resin particles is 40000, and the three solutions A, B and C are mixed in a mass ratio of 80:20:25. In the impregnating solution, the polyurethane resin accounts for 20% of the mass of the resin, the polyacrylic acid accounts for 0.8% of the mass of the resin, the content of the modified polyether sulfone resin is 19.2wt%, the content of the polyurethane resin in the impregnating solution is 4.8wt%, and the content of the pore-forming agent in the impregnating solution is 0.2wt%. Example 4 The present embodiment provides a specific method for preparing a polishing pad, and the preparation steps are basically the same as those of Example 1, except that: In step (2), the molecular weight of the modified polyether sulfone resin particles is 40000, the 100% modulus of the polyurethane resin is 15Mpa, the pore-forming agent is polyvinyl alcohol, and the three solutions A, B and C are mixed in a mass ratio of 80:20:25. In the impregnating solution, the polyurethane resin accounts for 20% of the mass of the resin, the polyvinyl alcohol accounts for 0.8% of the mass of the resin, the content of the modified polyether sulfone resin is 19.2wt%, the content of the polyurethane resin in the impregnating solution is 4.8wt%, and the content of the pore-forming agent in the impregnating solution is 0.2wt%. Example 5 The present embodiment provides a specific method for preparing a polishing pad, and the preparation steps are basically the same as those of Embodiment 1, except that: In step (2), the molecular weight of the modified polyether sulfone resin particles is 40000, the solid content of solutions A and B is 25%wt, and the three solutions A, B and C are mixed in a mass ratio of 80:20:25. In the impregnating solution, the polyurethane resin accounts for 20% of the mass of the resin, the polyacrylic acid accounts for 1% of the mass of the resin, and the modified polyether sulfone resin accounts for 16% of the mass of the resin. The content of polyurethane resin in the impregnating solution is 4.0wt%, and the content of pore-forming agent in the impregnating solution is 0.1wt%. Comparative Example 1 The present comparative example is a comparative example of Embodiment 3, except that: In step (2), the two solutions B and C are mixed in a mass ratio of 100:25, and the impregnating solution does not contain modified polyether sulfone resin. The polyacrylic acid accounts for 0.8% of the mass of the resin, and the 100% modulus of the polyurethane resin is 30Mpa. Comparative Example 2 The present comparative example is a comparative example of Embodiment 3, except that:

[0115] In step (2), the pore-forming agent is polyvinyl alcohol, and the two solutions A and C are mixed in a mass ratio of 100:25. The impregnating solution does not contain polyurethane resin, and the polyacrylic acid accounts for 0.8% of the mass of the resin. Comparative Example 3 The present comparative example is a comparative example of Embodiment 5, except that: In step (2), the impregnating solution does not contain pore-forming agent, and the rest is the same as Embodiment 5. The polyurethane resin accounts for 20% of the mass of the resin. Comparative Example 4 The present comparative example is a comparative example of Embodiment 1, except that: In step (2), the three solutions A, B and C are mixed in a mass ratio of 95:5:15. In the impregnating solution, the polyurethane resin accounts for 5% of the mass of the resin, and the polyacrylic acid accounts for 0.5% of the mass of the resin. Comparative Example 5 The present comparative example is a comparative example of Embodiment 1, except that: In step (2), the three solutions A, B and C are mixed in a mass ratio of 60:40:15. In the impregnating solution, the polyurethane resin accounts for 40% of the mass of the resin, and the polyacrylic acid accounts for 0.5% of the mass of the resin. Comparative Example 6 The present comparative example is a comparative example of Embodiment 3, except that: In step (2), the solid content of the prepared C solution was 0.12%. In the impregnating solution, the polyurethane resin accounted for 20% of the mass of the resin, and the polyacrylic acid accounted for 0.1% of the mass of the resin. Comparative Example 7 This comparative example is a comparative example of Example 3, the only difference being that: In step (2), the solid content of the prepared C solution was 1.8%. In the impregnating solution, the polyurethane resin accounted for 20% of the mass of the resin, and the polyacrylic acid accounted for 1.5% of the mass of the resin. Comparative Example 8 This comparative example is a comparative example of Example 3, the only difference being that: In step (2), the modified polyether sulfone was replaced by polyether sulfone, and the rest of the conditions remained unchanged. Molecular weight tests were performed on the polyether sulfone resin, and molecular weight and 100% modulus tests were performed on the polyurethane resin, with the test methods as follows: Molecular weight test: Gel permeation chromatography was used to determine the molecular weight. 100% Modulus Test Method: 1) Preparation of polyurethane sheet: PET plastic sheet was evenly attached to the four edges of the glass plate, and the polyurethane resin solution was poured onto the PET plastic sheet. A doctor blade was used to evenly coat the film on the smooth PET plastic sheet, and air bubbles were avoided as much as possible. The thickness of the film was 0.4 mm. 3) Drying: After being placed in a 50°C oven for 20 minutes, the temperature was increased to 120°C, and the sample was dried for 30 minutes. After natural cooling to room temperature, the polyurethane sheet was removed from the glass plate. 4) Storage: Packaged in a self-sealing bag and placed in a constant temperature room at 25°C±2°C for 4 hours before testing. 5) Preparation of the test sample (polyurethane sheet): The test sample was 20mm x 120mm, and the long edge direction was parallel to the coating direction during film preparation. The middle part with high thickness uniformity was selected, avoiding air bubbles, bumps, surface imperfections, and neat edges. Five effective sample strips were taken each time. The thickness of the test sample was measured at five points using a micrometer, and the average value (mm) was taken. 6) Tensile test of the test sample: The tensile tester was opened, the clamping distance of the tensile tester was 35mm, and the tensile speed was 200mm / min. The tensile load kgf at 100% elongation was obtained, and the 100% tensile modulus was calculated according to the following formula: 100% tensile modulus = tensile load kgf at 100% elongation / sample cross-sectional area (test sample width x thickness) cm 2 . The polishing pads prepared in Examples 1 to 5, Comparative Examples 1 to 8, and a commercially available product, silicon carbide polishing pad suba800 (manufactured by DuPont), were subjected to hardness test, density test, compression ratio and compression elastic modulus test, air permeability test, and oxidation resistance test, and the test results are shown in Table 1. The polishing pads of Example 3 and Comparative Examples 1 and 7 subjected to the oxidation resistance test are shown in FIGS. 7 to 9. The polishing pads prepared in Example 3, Comparative Examples 1 to 3, and Comparative Example 8, and the commercially available product suba800 were subjected to polishing rate test and scratch test, and the test results are shown in FIGS. 1 to 2 and Tables 2 to 3. The polishing pads prepared in Example 3 and Comparative Examples 6 to 7 were subjected to polishing rate test and scratch test, and the test results are shown in FIGS. 5 to 6 and Tables 2 to 3. The polishing pads prepared in Example 1 and Comparative Examples 4 to 5 were subjected to polishing rate test and scratch test, and the test results are shown in FIGS. 3 to 4 and Tables 2 to 3. The polishing pads of Example 3 and Comparative Examples 1 and 7 after 20 h of polishing test are shown in FIGS. 10 to 12. The test methods are as follows: 1. Hardness test: GB / T 2411-2008 was used for the test. 2. Density test: GB / T 6343-2009 was used to measure the apparent core density, and the size of the sample to be measured was 300 mm x 300 mm x 3.0 mm. 3. Compression ratio and compression elastic modulus test: Method A (constant pressure method) in GB / T 24442.1-2009 Textiles-Determination of compressional properties-Part 1: Constant rate of extension method was used for the test. 4. Air permeability test: A fabric air permeability tester was used, the model was G571, and the set parameters were: test area 38 cm 2 , test pressure 1000 Pa. 5. Oxidation resistance test: An alkaline potassium permanganate solution (mass fraction 5.2%, pH = 9) was prepared, and the polishing pad was immersed in the alkaline potassium permanganate solution for 24 h. The polishing pad was taken out and ultrasonically cleaned in water for 2 times, 10 min each time, then was ultrasonically cleaned in 2.5% oxalic acid solution for 10 min, and then was ultrasonically cleaned in water for 10 min to obtain a sample to be measured. The abrasion resistance of the sample to be measured was measured by a Taber abrasion tester, and a H-18 ceramic grinding wheel was used with a load of 1.5 kg, and the weight loss was tested after rotating at a speed of 75 rpm for 500 revolutions. 6. Polishing rate test: polish the 6 inch silicon carbide substrate by using Zhejiang Mingzheng 36B size single side polishing machine, record the polishing rate; Polishing machine: 915mm, polishing liquid is Borena polishing liquid for silicon carbide COPOL-233, polishing liquid flow rate 400ml / min, polishing pressure: 238g / cm 3 , lower disc rotation speed 40rpm. 7. Scratch detection: detect the scratches of the silicon carbide substrate polished by the polishing rate test, observe under the strong light lamp (Yamada optical YP250), bright lines longer than 2cm are determined as scratches, record the number of scratches. Table 1 Table 2 Table 3 From Table 1, it can be seen that: The air permeability of the polishing pads of Examples 1-5 of the present application is all above 100m 2 / s, while the air permeability of the polishing pad prepared in Comparative Example 3 is as low as 2m 2 / s, because no pore-forming agent is contained, indicating that the pore-forming agent can greatly improve the air permeability of the polishing pad; The wear amount of the polishing pads of Examples 1-5 of the present application is all controlled within 100mg, while the wear amount of the polishing pad of Comparative Example 1 reaches 623mg after 500 rounds of grinding after soaking in potassium permanganate solution, indicating that the modified polyether sulfone resin plays an important role in improving the oxidation resistance of the polishing pad. From Figure 1, it can be seen that: The polishing rate of Comparative Example 1 and the commercially available product suba800 decreases faster, because the polishing pad prepared in Comparative Example 1 and the commercially available product suba800 have very poor oxidation resistance, and with the extension of polishing time, the internal resin is severely eroded, affecting the overall physical properties, so the polishing rate decreases faster, and the polishing pad is seriously lost after 10h, so the test is stopped; The polishing rate of the polishing pad of Comparative Example 3 is lower than that of Examples 3 and Comparative Example 2, because no pore-forming agent is added, the internal pores are few, and the polishing liquid storage capacity is poor; The polishing rates of Examples 3 and Comparative Example 2 are relatively stable within 20h, and almost no attenuation occurs, and the oxidation resistance of the polishing pad of Comparative Example 2 is higher than that of Example 3 because it does not contain polyurethane resin, so the polishing rate of Comparative Example 2 is better than that of Example 3. From Figure 2, it can be seen that: The scratch number of the polishing pad of Comparative Example 2 is more than 10 on average, because the resin in the polishing pad is modified polyether sulfone resin, which has high hardness and poor elasticity, and has large friction with the surface of the SiC substrate during polishing, thereby generating a large number of scratches. The polishing pad of Comparative Example 3 has a large number of scratches, because the internal pores are few, causing the accumulation of abrasives, which easily scratches the SiC substrate during polishing. As shown in FIG. 3, the removal rate and stability of Example 1 and Comparative Example 4 are good, the polishing rate of Comparative Example 5 is slightly low, and the attenuation amplitude is also relatively large as the use time is prolonged, and finally, the removal rate is lower than 1.5 μm / h after 16 hours, which is caused by the small amount of modified polyether sulfone, which is not resistant to chemical oxidation. As shown in FIG. 4, the scratch number of Example 1 and Comparative Example 5 is controlled within the range of not more than 3, while Comparative Example 4 exceeds the standard, which shows that too much modified polyether sulfone component will make the hardness of the final product larger and the elasticity worse, causing too many scratches during polishing. As shown in FIG. 5, the removal rate and stability of Example 3 are good, the rate and stability of Comparative Example 6 are good, but the average removal rate of Comparative Example 6 is lower than that of Example 3, because the internal pore structure of Comparative Example 6 is less, which is not conducive to the flow of polishing liquid. The initial removal rate of Comparative Example 7 is good, but it has obvious attenuation in the later stage, and is lower than 1.5 μm / h after 18 hours, which is because too many pore structures will accelerate the corrosion of potassium permanganate in the polishing liquid to the inside of the polishing pad, thereby causing the removal rate to decrease. As shown in FIG. 6, the scratch number of Example 3 and Comparative Example 7 is within 3, and Comparative Example 6 exceeds the standard obviously, which is because the few pore structures make the abrasives in the polishing liquid and the impurities removed by polishing more easily blocked in the polishing pad, thereby causing scratches during polishing. As shown in FIGS. 7-9, the polishing pad surface of Example 3 is basically free of fluff, the polishing pad surface of Comparative Example 1 exposes a lot of fiber fluff, because the polishing pad does not contain modified polyether sulfone resin, and the polishing pad surface of Comparative Example 7 has some fluff, because the content of modified polyether sulfone resin is less. As shown in FIGS. 10-12, the polishing pad surface of Example 3 is basically free of fluff, the polishing pad surface of Comparative Example 1 exposes a lot of fiber fluff, because the polishing pad does not contain modified polyether sulfone resin, and the polishing pad surface of Comparative Example 7 has some fluff, because the content of modified polyether sulfone resin is less. The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A polishing pad, characterized by, The base material is impregnated with a resin material, the raw material components of which include resin and pore-forming agent; the resin includes modified polyether sulfone resin and polyurethane resin; the polyurethane resin accounts for 10% ~ 30% of the mass of the resin; the modified polyether sulfone resin accounts for 70% ~ 90% of the mass of the resin; the pore-forming agent accounts for 0.3 ~ 1% of the mass of the resin; the modified polyether sulfone resin is obtained through grafting reaction of acrylic acid and polyether sulfone; the mass ratio of the polyether sulfone to the acrylic acid is 10: (0.1 ~ 1); the pore-forming agent is selected from polyacrylic acid and / or polyvinyl alcohol; the weight average molecular weight of the modified polyether sulfone resin is 10000 ~ 70000; the 100% modulus of the polyurethane resin is 1 ~ 15Mpa.

2. The polishing pad of claim 1, wherein The raw material components further include a first solvent selected from one or more of N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

3. The polishing pad of claim 1, wherein, The base material is selected from one of fabric, non-woven fabric or woven fabric; and / or, the fiber fineness of the fiber raw material of the base material is 2.6 ~ 3 denier.

4. The polishing pad of claim 1, wherein, The polishing pad includes one or more of the following features: a) density of 0.4 ~ 0.5 g / cm 3 ; b) Shore A hardness of 80 ~ 91 HA; c) compression rate of 2.0 ~ 4.0%; d) compression elasticity rate of 60 ~ 75%; e) air permeability of not less than 100 m 2 / S; f) after soaking in a basic potassium permanganate solution with a concentration of 4.5 ~ 5.5% and a pH of 8.5 ~ 9.5, using H-18 ceramic grinding wheel with a load of 1 ~ 2 kg weight for abrasion, rotating at a speed of 60 ~ 75 rpm for 500 ~ 600 revolutions, the wear amount is not higher than 100mg.

5. A method of making a polishing pad as claimed in any one of claims 1 to 4, characterised in that, The method includes the following steps: 1) mixing the raw material components to form a homogeneous impregnating solution; 2) impregnating the base material in the impregnating solution, and then placing it in a coagulation solution for coagulation treatment to obtain the polishing pad.

6. The preparation method according to claim 5, characterized in that, In the impregnating solution, the content of the modified polyether sulfone resin is 15 ~ 25wt%; And / or, in the impregnating solution, the content of the polyurethane resin is 2 ~ 10wt%; And / or, in the impregnating solution, the content of the pore-forming agent is 0.1 ~ 0.2wt%; And / or, after impregnation, a rolling treatment is further performed; And / or, the coagulation solution is an aqueous solution of N, N-dimethylformamide; and / or, after coagulation treatment, one or more of the following treatments is performed: water washing, drying, polishing, grooving treatment; And / or, the thickness of the base material is 1.8 ~ 2.2mm, and the gram weight is 270 ~ 330g / cm 2 .

7. The method of claim 6, wherein the method further comprises the step of: In the coagulation solution, the content of the N, N-dimethylformamide is 15 ~ 25wt%; and / or, the rolling speed is 1 ~ 5r / min, and the rolling pressure is 0.1 ~ 1Mpa.

8. Use of the polishing pad according to any one of claims 1 ~ 4 as a polishing pad for polishing silicon carbide substrate in chemical mechanical polishing.

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