CN119036303A

CN119036303A - Polishing pad and preparation method and application thereof

Info

Publication number: CN119036303A
Application number: CN202411062718.3A
Authority: CN
Inventors: 王海波; 王晨
Original assignee: Quzhou Bolai Narun Electronic Materials Co ltd; Shanghai Yingzhi Abrasive Materials Co ltd
Current assignee: Quzhou Bolai Narun Electronic Materials Co ltd; Shanghai Yingzhi Abrasive Materials Co ltd
Priority date: 2024-08-05
Filing date: 2024-08-05
Publication date: 2024-11-29
Anticipated expiration: 2044-08-05

Abstract

本发明提供一种抛光垫及其制备方法和用途，所述抛光垫包括基底材料和附着于所述基底材料上面的树脂层，所述树脂层的原料组分包括树脂和造孔剂；所述树脂包括改性聚醚砜树脂和聚氨酯树脂。本申请采用改性聚醚砜树脂作为抛光垫树脂，大大提高了抛光垫的耐氧化性，进而提高了抛光垫用于抛光SiC衬底的使用寿命，提高了耐用性。The present invention provides a polishing pad and a preparation method and use thereof, wherein the polishing pad comprises a base material and a resin layer attached to the base material, wherein the raw material components of the resin layer comprise a resin and a pore-forming agent; and the resin comprises a modified polyethersulfone resin and a polyurethane resin. The present application adopts a modified polyethersulfone resin as the polishing pad resin, which greatly improves the oxidation resistance of the polishing pad, thereby increasing the service life of the polishing pad for polishing a SiC substrate and improving the durability.

Description

Polishing pad and preparation method and application thereof

Technical Field

The invention relates to the field of CMP material preparation in silicon carbide substrate processing, in particular to a polishing pad, and a preparation method and application thereof.

Background

Silicon carbide (SiC) is used as a third generation wide bandgap semiconductor material, has the characteristics of large bandgap width, high thermal conductivity, high critical breakdown field strength, high electron saturation drift rate and the like, can effectively break through the physical limit of the traditional silicon-based semiconductor device and the material thereof, and develops a new generation semiconductor device more suitable for conditions of high voltage, high temperature, high power, high frequency and the like. SiC is a third-rank material in the world hardness, and not only has the characteristic of high hardness, but also causes brittle fracture of a material easily in the grinding process of SiC due to high brittleness and low fracture toughness, so that a surface fracture layer is left on the surface of the material, and serious surface and subsurface damage is generated, thereby affecting the processing precision.

The silicon carbide has high processing difficulty in the cutting, grinding and polishing stages, and mainly comprises (1) high hardness, mohs hardness distribution of 9.2-9.6, (2) high chemical stability, hardly reacts with any strong acid or strong alkali, and (3) immature processing equipment. The substrate processing procedure is complicated, and the low-efficiency and complex processing technology leads to serious insufficient productivity and yield. In order to realize high removal and planarization of the silicon carbide substrate, the existing double-sided CMP process of the silicon carbide substrate adopts a non-woven fabric polishing pad to be matched with a potassium permanganate system polishing solution, however, potassium permanganate is a strong oxidant and can corrode a polyurethane coating of the non-woven fabric polishing pad, polyurethane impregnated on the non-woven fabric is easy to fall off in the CMP process with high pressure and high rotating speed, the non-woven fabric polishing pad is fluffed, fibers fall off to block a filter screen, polishing removal rate is reduced and the like.

The invention CN200880003811 adopts the mode of bundling fiber, and the superfine single fiber forming the fiber bundle is bundled to exist in the state of one crude fiber, thereby obtaining the polishing pad with high rigidity. The patent CN108349062 carries out warp and weft knitting on raw material fibers, modifies the raw material, enhances the toughness and strength of the non-woven fabric, and thereby improves the hardness of the final product. In CN201480007963, a secondary impregnation method is adopted to impregnate the softer polyurethane resin in advance, and after solidification, another resin is impregnated, so that curing and crosslinking can be performed, and the performance of the final product can be improved. The invention patent JP2012101333A discloses a preparation process of polishing pad, which adopts a wet coating process to coat a resin layer on the plastic film, improves the mechanical strength of the final product by mixing two resins with different hardness, and improves the pore structure by wet solidification, but after the product prepared by the method is oxidized, the molecular bond of the resin film is broken once, and the resin film on the surface of the product is easily cracked, thereby influencing the polishing effect.

The method has the defects that the working procedures are complicated, the operation is complex, the mechanical property of the polishing pad is improved, the polishing efficiency can be improved to a certain extent, and the polishing pad still has durability due to the influence of a strong oxidant in the polishing solution.

Disclosure of Invention

In view of the above-described drawbacks of the prior art, an object of the present invention is to provide a polishing pad, and a method of manufacturing and use thereof, for solving the problems of the prior art.

To achieve the above and other related objects, the present invention is achieved by the following technical means.

The invention discloses a polishing pad, which comprises a base material, wherein the base material is impregnated with a resin material, the raw material components of the resin material comprise resin and pore-forming agent, and the resin comprises modified polyethersulfone resin and polyurethane resin.

Preferably, the polyurethane resin accounts for 10% -30% of the mass of the resin. For example, the content may be 10% to 20% and 20% to 30%. The more the polyurethane resin is used, the better the toughness and the poorer the oxidation resistance of the polishing pad.

Preferably, the modified polyethersulfone resin accounts for 70-90% of the mass of the resin. For example, the content may be 70 to 80% or 80 to 90%.

Preferably, the pore-forming agent accounts for 0.3-1% of the mass of the resin. For example, the content may be 0.3 to 0.5%, 0.5 to 0.8%, 0.8 to 1.0%. The more pore-forming agent is used, the better the air permeability, the poorer the oxidation resistance and the better the toughness of the polishing pad. The more the resin is used, the poorer the air permeability, the better the oxidation resistance and the poorer 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 to 60000. For example, 20000 to 30000, 30000 to 40000, 40000 to 50000, 50000 to 60000 are possible.

More preferably, the weight average molecular weight of the polyvinyl alcohol is 50000-100000. The number of the components may be 50000 to 75000, 75000 to 80000, 80000 to 90000, 00000 to 100000.

Preferably, the modified polyethersulfone resin is obtained by grafting reaction of acrylic acid and polyethersulfone.

More preferably, the mass ratio of the polyethersulfone to the acrylic acid is 10 (0.1-1). For example, 10 (0.1 to 0.3), 10 (0.3 to 0.5), 10 (0.5 to 0.7) and 10 (0.7 to 1).

Preferably, the polyethersulfone resin has a weight average molecular weight of 10000-70000. The number of the groups may be 10000 to 20000, 20000 to 30000, 30000 to 40000, 40000 to 50000, 50000 to 60000, 60000 to 70000, more preferably 30000 to 50000.

Preferably, the 100% modulus of the polyurethane resin is 1-15 mpa. For example, it may be 1 to 5MPa, 5 to 7MPa 7-10 mpa and 10-15 mpa.

Preferably, the feed component further comprises a first solvent selected from one or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone and dimethylsulfoxide.

Preferably, the base material is selected from one of a fabric, a nonwoven fabric, or a woven fabric. The resin material is filled between the fibers of the base material, and when oxidized, even if molecular bonds of the resin material are broken, the polishing pad is not broken, so that the polishing effect is affected.

More preferably, the fiber raw material of the non-woven fabric comprises one or more of polypropylene fiber, terylene, chinlon, viscose fiber, acrylic fiber, polyethylene fiber, polyvinyl chloride fiber, polyester fiber and polyamide fiber.

Preferably, the fiber fineness of the fiber raw material of the substrate material is 2.6-3.0 denier.

Preferably, the polishing pad comprises 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 elastic rate of 60-75%, e) air permeability of not less than 100m ²/S, f) abrasion is carried out by adopting H-18 ceramic grinding wheel load of 1-2 kg weight after being soaked in alkaline potassium permanganate solution with concentration of 4.5-5.5 and pH of 8.5-9.5, and the abrasion amount is not more than 100mg after rotating for 500-600 circles at a rotating speed of 60-75 rpm.

For example, the polishing pad can have a gas permeability of 102m ²/S、110m²/S、185m²/S、191m²/S、233m²/S.

For example, the amount of wear of the polishing pad may be 41mg, 57mg, 61mg, 67mg.

The invention also discloses a preparation method of the polishing pad, which comprises the following steps:

1) Mixing the raw material components to form a homogeneous impregnation liquid;

2) And (3) immersing the substrate material in the immersion liquid, and then placing the substrate material in a coagulating liquid for coagulating treatment to obtain the polishing pad.

Preferably, in the impregnating solution, the content of the modified polyethersulfone resin is 15-25wt%. The content of the polymer may be 15-16wt%, 16-18.3wt%, 18.3-19.2wt%, 19.2-20wt%, 20-23.5wt%, and 23.5-25wt%.

Preferably, in the impregnation liquid, the content of the polyurethane resin is 2-10wt%. The content of the catalyst may be 2-2.6wt%, 2.6-4wt%, 4-4.8wt%, 4.8-7.8wt%, and 7.8-10wt%.

Preferably, in the impregnation liquid, the content of the pore-forming agent is 0.1-0.2wt%.

Preferably, the modified polyethersulfone resin is subjected to drying pretreatment before use, and the drying temperature is 110-130 ℃.

Preferably, the substrate material is subjected to drying pretreatment before the impregnation treatment, and the drying temperature is 90-120 ℃.

Preferably, the impregnation liquid is subjected to a vacuum degassing treatment before the impregnation treatment.

Preferably, the impregnation is further followed by a roll-in treatment.

More preferably, the rotational speed of the rubber roller is 1-5 r/min, and the rolling pressure is 0.1-1.0 mpa.

Preferably, the coagulating liquid is an aqueous solution of N, N-dimethylformamide.

More preferably, the content of the N, N-dimethylformamide in the coagulating liquid is 17 to 22wt%. For example, the content may be 15 to 20wt% or 20 to 25wt%.

Preferably, the solidification treatment is followed by one or more selected from the group consisting of water washing, drying, polishing, grooving.

More preferably, the drying temperature is 120-130 ℃ and the drying time is 2-3 h. For example, the drying temperature may be 100-110 ℃, 110-120 ℃, 120-130 ℃, 130-140 ℃, 140-150 ℃.

More preferably, the polishing is performed by polishing two sides of the polishing pad with sand paper, and the number of sand paper is 170-200 meshes.

Preferably, the thickness of the substrate material is 1.8-2.2 mm, and the gram weight is 270-330 g/cm ².

The invention also discloses the use of the polishing pad as described above in chemical mechanical polishing as a polishing pad for polishing a silicon carbide substrate.

The invention discloses a polishing pad, a preparation method and application thereof, and the polishing pad has the following beneficial effects:

The application adopts the modified polyethersulfone resin as polishing pad resin, greatly improves the oxidation resistance of the polishing pad, further improves the service life of the polishing pad for polishing SiC substrates, improves the durability, adds a certain amount of low-modulus polyurethane resin into the modified polyethersulfone resin, improves the toughness of the polishing pad while ensuring the oxidation resistance, ensures certain rebound capability, and adds a small amount of pore-forming agent to improve the porosity of the polishing pad. The prepared polishing pad has better oxidation resistance, air permeability and toughness through the specific proportion among the components, and when being used for polishing a SiC substrate, the polishing rate and the substrate surface quality are better, and meanwhile, the service life of the polishing pad is prolonged. The preparation method is simple, only one-step dipping and solidification is needed, no other working procedures are needed, the production efficiency is high, the cost is low, and the method is suitable for industrial mass production.

Drawings

FIG. 1 is a graph showing the results of polishing rates of polishing pads prepared in example 3 of the present invention and comparative examples 1 to 3 and 8 and commercially available polishing pad suba.

FIG. 2 is a graph showing the effect of testing the number of scratches on the polishing pads prepared in example 3 of the present invention and comparative examples 1 to 3 and 8 and the commercially available polishing pad suba.

FIG. 3 is a graph showing the effect of polishing rate test on polishing pads prepared in example 1 and comparative examples 4 to 5 of the present invention.

FIG. 4 is a graph showing the effect of testing the number of scratches on the polishing pads prepared in example 1 and comparative examples 4 to 5 of the present invention.

FIG. 5 is a graph showing the effect of polishing rate test on polishing pads prepared in example 3 and comparative examples 6 to 7 of the present invention.

FIG. 6 is a graph showing the effect of testing the number of scratches on the polishing pads prepared in example 3 and comparative examples 6 to 7 of the present invention.

FIG. 7 is a graph showing the surface effect of the polishing pad prepared in example 3 of the present invention after the oxidation resistance test.

FIG. 8 is a graph showing the surface effect of the polishing pad prepared in comparative example 1 according to the present invention after the oxidation resistance test.

FIG. 9 is a graph showing the surface effect of the polishing pad prepared in comparative example 7 according to the present invention after the oxidation resistance test.

FIG. 10 is a graph showing the surface effect of the polishing pad prepared in example 3 according to the present invention after 20 hours polishing rate test.

FIG. 11 is a graph showing the surface effect of the polishing pad prepared in comparative example 1 according to the present invention after 20 hours polishing rate test.

FIG. 12 is a graph showing the surface effect of the polishing pad prepared in comparative example 7 according to the present invention after 20 hours polishing rate test.

Detailed Description

Further advantages and effects of the present invention will become apparent to those skilled in the art from the disclosure of the present invention, which is described by the following specific examples.

Before further describing embodiments of the invention, it is to be understood that the scope of the invention is not limited to the specific embodiments described below, and that the terminology used in the examples of the invention is intended to be in the nature of specific embodiments and is not intended to be limiting of the scope of the invention. The test methods in the following examples, in which specific conditions are not noted, are generally conducted under conventional conditions or under conditions recommended by the respective manufacturers.

Where numerical ranges are provided in the examples, it is understood that unless otherwise stated herein, both endpoints of each numerical range and any number between the two endpoints are significant both in the numerical range. Unless defined otherwise, 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 invention belongs. In addition to the specific methods, devices, materials used in the embodiments, any methods, devices, and materials of the prior art similar or equivalent to those described in the embodiments of the present invention may be used to practice the present invention according to the knowledge of one skilled in the art and the description of the present invention.

The modified polyethersulfone resin of the invention is prepared by the following method:

And under the anaerobic atmosphere, placing the homogeneous solution under a radiation source for radiation reaction, wherein the radiation reaction temperature is 10-30 ℃, the radiation dose rate is 0.5-5 kGy/h, and the total radiation dose is 5-30 kGy. And after the reaction is finished, reversely precipitating the homogeneous phase solution in an aqueous solution, repeatedly washing for many times, soaking in water for 20-30 h, and drying in vacuum.

The pretreatment method of the polyethersulfone resin comprises the steps of washing the polyethersulfone resin in water, soaking for more than one week, changing water for multiple times during the soaking, and drying to constant weight under the conditions of vacuum and 70-80 ℃.

Specifically, the second solvent is selected from one or more of N-methylpyrrolidone, N-dimethylformamide, N-dimethylacetamide and dimethylsulfoxide.

Specifically, the mass ratio of the polyether sulfone to the acrylic monomer is 10 (0.1-1).

Specifically, the amount of the polyethersulfone in the homogeneous solution is 5-20wt%.

In particular, the radiation source is typically a gamma radiation source, preferably ⁶⁰C_O.

Specifically, the oxygen-free atmosphere may be purged of oxygen by the introduction of nitrogen and/or inert gas.

The invention further provides a preparation method of the specific polishing pad, which comprises the following preparation steps:

(1) Preparing an impregnating solution:

Weighing a certain amount of modified polyethersulfone resin powder, drying in an oven at 110-130 ℃ for 12-24 hours, removing possible residual moisture, adding DMF, stirring for 30-45 minutes by a high-speed shearing and dispersing machine to enable the DMF to be fully dissolved to form a solution A, wherein the solid content is 20-35%wt, and the weight average molecular weight of the modified polyethersulfone powder is 10000-70000.

Weighing a certain amount of polyurethane resin solution, adding DMF, stirring and dispersing at a high speed for 30-45 min by a stirrer to form a solution B, and controlling the solid content to be 20-35% wt. The 100% modulus of the polyurethane resin is 1-15Mpa.

Weighing a certain amount of pore-forming agent, adding the pore-forming agent into a first solvent DMF, and stirring and dispersing at a high speed for 30-45 min to obtain a solution C with a solid content of 1-5%wt. Wherein the pore-forming agent is selected from polyacrylic acid and/or polyvinyl alcohol.

Mixing A, B, C solutions according to the mass ratio of 60-80:10-30:10-30, stirring and defoaming to form an impregnating solution, and standing for later use.

(2) Wet forming of polishing pad:

And (3) pre-treating the non-woven fabric base cloth in an oven at 100-150 ℃ for 1-2 hours to remove water, then immersing the non-woven fabric base cloth in impregnating solution, and extruding superfluous floating materials on the surface by using a compression roller. Immersing the non-woven fabric base fabric into the coagulating liquid to coagulate the resin on the non-woven fabric fibers. Washing with water, drying at 120-130 ℃ for 2-3 hours, thus obtaining the semi-finished product of the polishing pad.

The coagulating liquid is an aqueous solution of N, N-dimethylformamide, and the concentration is 15-25wt%. The non-woven fabric is made of short fibers by adopting a needling molding process, and the fiber raw material is selected from one of polypropylene, terylene, chinlon, viscose, acrylic, polyethylene, chlorlon, polyester and polyamide. The fineness of the fiber raw material is 2.6-3.0 denier. The thickness of the non-woven fabric is 1.8-2.2 mm, the gram weight is 270-330 g/cm ².

(3) Polishing pad processing

And (3) polishing two sides of the semi-finished polishing pad, wherein the number of sand paper is 170-200 meshes, and the thickness of the product is controlled to be 1-1.5 mm. And then, adhering the double-sided adhesive tape on one side, and grooving on the other side to obtain the finished polishing pad product.

More specific examples are provided below, and the reagents and instruments used in the examples below are all conventionally used reagents, and are commercially available, as follows:

Polyurethane resin solution, available from Xuchuan chemical, was at a concentration of 35wt%. Is 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 was 40000 and the weight average molecular weight of polyvinyl alcohol was 75000.

Example 1

The embodiment provides a specific preparation method of a polishing pad, which comprises the following preparation steps:

(1) The preparation of the modified polyethersulfone resin comprises the steps of weighing 10g of pretreated polyethersulfone powder, dissolving the polyethersulfone powder in 86gDMF solvent, adding 1g of acrylic acid monomer, stirring for 24 hours at 60 ℃ to obtain a homogeneous solution, continuously introducing N ₂ min, placing the homogeneous solution under a ⁶⁰C_O source, and carrying out irradiation reaction at 20 ℃ at an irradiation dose rate of 1kGy/h and an absorption dose of 17kGy.

After the irradiation reaction, the homogeneous solution is reversely precipitated in the water solution, repeatedly washed and soaked in deionized water for 24 hours, and then dried to constant weight in a vacuum drying oven (80 ℃).

(2) Preparing an impregnating solution:

a certain amount of modified polyethersulfone resin powder is weighed, added with DMF and stirred by a high-speed shearing and dispersing machine for 30min to be fully dissolved to form solution A, and the solid content is 30%wt, wherein the weight average molecular weight of the polyethersulfone powder is 50000.

A certain amount of polyurethane resin solution is weighed, DMF is added, and a stirrer is used for stirring and dispersing for 30min at a high speed to form solution B, and the solid content is controlled at 30%wt. The 100% modulus of the polyurethane resin is 7Mpa.

A certain amount of polyacrylic acid is weighed and added into a first solvent DMF, and the mixture is stirred and dispersed at a high speed for 30min to obtain a solution C with a solid content of 1%wt.

Mixing A, B, C solutions according to the mass ratio of 90:10:15, stirring and defoaming to form an impregnating solution, and standing for later use. 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% by weight, the content of the polyurethane resin in the impregnating solution is 2.6% by weight, and the content of the pore-forming agent in the impregnating solution is 0.1% by weight.

(3) Wet forming of polishing pad:

and (3) pre-treating the non-woven fabric base cloth in an oven at 100 ℃ for 2 hours to remove water, then immersing the non-woven fabric base cloth in an impregnating solution, and extruding superfluous floating materials on the surface by using a compression roller. Immersing the non-woven fabric base fabric into the coagulating liquid to coagulate the impregnating liquid on the non-woven fabric fibers. And (5) washing with water, and drying at 120 ℃ for 2 hours to obtain the polishing pad semi-finished product.

The coagulating liquid was an aqueous solution of N, N-dimethylformamide, and the concentration of N, N-dimethylformamide was 20wt%. The non-woven fabric is made of short fibers by adopting a needling molding process, and the fiber raw material is selected from polyester short fibers with the fineness of 3 denier. The nonwoven fabric had a thickness of 2mm and a grammage of 300g/m ².

(4) Polishing pad processing

And (3) polishing two sides of the semi-finished polishing pad, wherein the number of sand paper is 180, and the thickness of the product is controlled to be 1.3mm. And then, adhering the double-sided adhesive tape on one side, and grooving on the other side to obtain the finished polishing pad product.

Example 2

This example provides a specific method of preparing a polishing pad, the preparation steps being substantially the same as those of example 1, except that:

In the step (2), the pore-forming agent is polyvinyl alcohol, and the three solutions A, B, C are mixed according to the 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 18.3% by weight, the content of the polyurethane resin in the impregnating solution is 7.8% by weight, and the content of the pore-forming agent in the impregnating solution is 0.1% by weight.

Example 3

In the step (2), the molecular weight of the modified polyethersulfone resin particles is 40000, and the three solutions A and B, C are mixed according to the 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 polyethersulfone resin is 19.2% by weight, the content of the polyurethane resin in the impregnating solution is 4.8% by weight, and the content of the pore-forming agent in the impregnating solution is 0.2% by weight.

Example 4

In the step (2), the molecular weight of the modified polyethersulfone resin particles is 40000, the 100% modulus of the polyurethane resin is 15Mpa, the pore-forming agent is polyvinyl alcohol, and the A, B, C solutions are mixed according to the 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 polyethersulfone resin is 19.2% by weight, the content of the polyurethane resin in the impregnating solution is 4.8% by weight, and the content of the pore-forming agent in the impregnating solution is 0.2% by weight.

Example 5

In the step (2), the molecular weight of the modified polyethersulfone resin particles is 40000, the solid content of the solution A and the solution B is 25% by weight, and the solution A and the solution B, C are mixed according to the 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, the content of the modified polyethersulfone resin is 16% by weight, the content of the polyurethane resin in the impregnating solution is 4.0% by weight, and the content of the pore-forming agent in the impregnating solution is 0.1% by weight.

Comparative example 1

This comparative example is a comparative example of example 3, differing only in that:

In the step (2), B, C solutions are mixed according to the mass ratio of 100:25, the impregnating solution does not contain modified polyethersulfone resin, polyacrylic acid accounts for 0.8% of the mass of the resin, and the 100% modulus of polyurethane resin is 30Mpa.

Comparative example 2

in the step (2), the pore-forming agent is polyvinyl alcohol, and A, C solutions are mixed according to the mass ratio of 100:25. The impregnating solution does not contain polyurethane resin, and polyacrylic acid accounts for 0.8% of the mass of the resin.

Comparative example 3

This comparative example is a comparative example of example 5, differing only in that:

In the step (2), the impregnating solution does not contain a pore-forming agent, and the rest is the same as in the example 5, wherein the polyurethane resin accounts for 20% of the mass of the resin.

Comparative example 4

This comparative example is a comparative example of example 1, and differs only in that:

In the step (2), A, B, C solutions are mixed according to the mass ratio of 95:5:15. In the impregnating solution, polyurethane resin accounts for 5% of the mass of the resin, and polyacrylic acid accounts for 0.5% of the mass of the resin.

Comparative example 5

in the step (2), A, B, C solutions are mixed according to the mass ratio of 60:40:15. In the impregnating solution, polyurethane resin accounts for 40% of the mass of the resin, and polyacrylic acid accounts for 0.5% of the mass of the resin.

Comparative example 6

in the step (2), the solid content of the prepared C solution is 0.12%. In the impregnating solution, polyurethane resin accounts for 20% of the mass of the resin, and polyacrylic acid accounts for 0.1% of the mass of the resin.

Comparative example 7

In the step (2), the solid content of the prepared C solution is 1.8%. In the impregnating solution, polyurethane resin accounts for 20% of the mass of the resin, and polyacrylic acid accounts for 1.5% of the mass of the resin.

Comparative example 8

in the step (2), the modified polyethersulfone is replaced by polyethersulfone, and the rest conditions are unchanged.

The polyether sulfone resin was subjected to a molecular weight test, and the polyurethane resin was subjected to a molecular weight test and a 100% modulus test by the following methods:

Molecular weight measurement the molecular weight was determined by gel permeation chromatography.

100% Modulus test method:

1) The preparation of the polyurethane sheet comprises the steps of flatly attaching four sides of a PET plastic sheet to a glass plate, pouring polyurethane resin solution on the PET plastic sheet, uniformly scraping a film on the flatly and smoothly PET plastic sheet by using a scraping rod, and avoiding scraping and coating bubbles as much as possible, wherein the thickness of the film is 0.4mm.

3) Drying, namely placing the polyurethane sheet into a 50 ℃ oven for constant temperature drying for 20 minutes, heating to 120 ℃, drying for 30 minutes, taking out, naturally cooling to room temperature, and tearing the polyurethane sheet from the glass plate.

4) Preserving, namely filling the mixture into a self-sealing pocket, and testing the mixture after the mixture is placed into a constant temperature chamber with the temperature of 25 ℃ plus or minus 2 ℃ for 4 hours.

5) Preparation of sample bars (polyurethane sheets) to be tested:

the length direction of the sample to be measured is 20mm multiplied by 120mm, the length direction of the sample to be measured is parallel to the knife coating direction in film preparation, the middle part with high thickness uniformity is selected, bubbles, concave-convex points are avoided, the surface is flawless, the incision edge is neat, and 5 effective sample strips are taken each time.

The thickness of 5 points of the sample strip to be measured is averaged (mm) with a thousandth gauge.

6) And (3) testing the tensile test of the sample strip to be tested:

opening the tensile machine, wherein the clamping distance of the tensile machine is 35mm, the stretching speed is 200mm/min, the tensile load kgf when the stretching degree is 100% is obtained, the 100% stretching modulus is calculated according to the following formula,

100% Tensile modulus=tensile load kgf/sample cross-sectional area (width of sample to be measured×thickness) cm ² at 100% elongation.

Polishing pads prepared in examples 1 to 5 and comparative examples 1 to 8 and commercially available silicon carbide polishing pad suba (DuPont) were subjected to hardness test, density test, compression ratio and compression elastic modulus test, air permeability test and oxidation resistance test, respectively, 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 fig. 7 to 9.

Polishing pads prepared in example 3, comparative examples 1 to 3, comparative example 8 and commercially available product suba were subjected to polishing rate test and scratch detection, respectively, and the test results are shown in fig. 1 to 2 and tables 2 to 3.

Polishing pads prepared in example 3 and comparative examples 6 to 7 were subjected to polishing rate test and scratch detection, respectively, and the test results are shown in fig. 5 to 6 and tables 2 to 3.

Polishing pads prepared in example 1 and comparative examples 4 to 5 were subjected to polishing rate test and scratch detection, respectively, and the test results are shown in fig. 3 to 4 and tables 2 to 3.

The polishing pads of example 3 and comparative examples 1 and 7 after 20h polishing test are shown in fig. 10 to 12.

The test method is as follows:

1. hardness test, namely using GB/T2411-2008 test;

2. density testing, namely measuring apparent core density by using GB/T6343-2009, wherein the size of a sample to be tested is 300mm multiplied by 3.0mm;

3. Compression ratio and compression elasticity rate test, namely, adopting a method A (constant pressure method) in a section 1 of measurement of compression performance of GB/T24442.1-2009 textile, namely, constant method;

4. Air permeability test, namely fabric air permeability tester equipment, model G571, setting parameters, namely test area 38cm ² and test pressure 1000Pa.

5. Oxidation resistance test:

Preparing an alkaline potassium permanganate solution (the mass fraction of which is 5.2 percent and the pH value is=9), soaking a polishing pad in the alkaline potassium permanganate solution for 24 hours, taking out the polishing pad, putting the polishing pad into clear water for ultrasonic cleaning for 2 times, putting the polishing pad into 2.5 percent oxalic acid solution for ultrasonic cleaning for 10 minutes each time for 10 minutes, and then putting the polishing pad into clear water for ultrasonic cleaning for 10 minutes to obtain a sample to be tested. The abrasion resistance of the sample to be measured was measured by a Taber abrasion tester, abrasion was performed by using a load of 1.5kg of the H-18 ceramic grinding wheel, and the loss mass was measured after 500 rotations at 75 rpm.

6. Polishing rate test, namely polishing a 6-inch silicon carbide substrate by adopting a Zhejiang single-sided polishing machine with the size of 36B, recording the polishing rate, wherein a polishing table is 915mm, polishing liquid adopts Boleno wetting silicon carbide polishing liquid COPOL-233, the flow rate of the polishing liquid is 400ml/min, the polishing pressure is 238g/cm ³, and the rotating speed of a lower disc is 40rpm.

7. Scratch detection the silicon carbide substrate tested for polishing rate was subjected to scratch detection, and the number of scratches was recorded as judged by visual observation under a strong light (mountain land optical YP 250) with a bright line exceeding 2cm in length.

TABLE 1

TABLE 2

TABLE 3 Table 3

As can be seen from table 1:

The air permeability of the polishing pads prepared in the examples 1-5 of the application is above 100m ²/s, and the air permeability of the polishing pad prepared in the comparative example 3 is as low as 2m ²/s because the pore-forming agent is not contained, which indicates that the pore-forming agent can greatly improve the air permeability of the polishing pad;

in the application, the abrasion loss of the polishing pad is controlled within 100mg in all the examples 1-5, but in the comparative example 1, the abrasion loss reaches 623mg after the potassium permanganate solution is soaked and ground for 500 circles because the modified polyethersulfone resin is not contained, which shows that the modified polyethersulfone resin plays an important role in improving the oxidation resistance of the polishing pad.

As can be seen from fig. 1:

The polishing rates of comparative example 1 and commercial product suba800,800 decreased rapidly because the polishing pad prepared in comparative example 1 and commercial product suba800,800 had poor oxidation resistance, and the internal resin was severely corroded with the increase of polishing time, affecting the overall physical properties, so that the polishing rate decreased rapidly, and the polishing pad lost seriously after 10 hours, stopping the test;

The polishing pad of comparative example 3 had less internal voids and poor ability to store polishing liquid because no pore-forming agent was added, and therefore, the polishing rate was lower than that of example 3 and comparative example 2;

the polishing rates of example 3 and comparative example 2 were relatively stable within 20 hours with little decay, and the polishing pad of comparative example 2 was superior to example 3 in terms of oxidation resistance, since it did not contain polyurethane resin, to example 3.

As can be seen from fig. 2:

The polishing pad of comparative example 2 had an average number of scratches of 10 or more, because the polishing pads were each made of a modified polyethersulfone resin, which had higher hardness and poorer elasticity, and had a larger friction with the SiC substrate surface during polishing, resulting in a large number of scratches;

the polishing pad of comparative example 3 had a large number of scratches because of the small internal voids, resulting in the accumulation of abrasive materials, which easily scratched the SiC substrate during polishing.

As can be seen from FIG. 3, the removal rates and stability of example 1 and comparative example 4 were good, the polishing rate of comparative example 5 was slightly lower, and the decay amplitude was also larger with the use time, and after the last 16 hours, it was lower than 1.5 μm/h, which was caused by the insufficient chemical oxidation resistance due to the low content of the modified polyethersulfone.

As can be seen from FIG. 4, the number of scratches in each of example 1 and comparative example 5 was controlled within a range of not more than 3, while comparative example 4 exceeded the standard, indicating that too much modified polyethersulfone component resulted in a final product having a large hardness and poor elasticity, resulting in too many scratches during polishing.

As can be seen from FIG. 5, the removal rate and stability of example 3 were good, and the rate stability of comparative example 6 was good, but the average removal rate was lower than that of example 3, because the internal pore structure of comparative example 6 was small, which was detrimental to the flow-through of the polishing liquid. The initial removal rate of comparative example 7 was good, but there was a significant decay at the later stage, below 1.5 μm/h after 18 hours, because excessive pore structure would accelerate the corrosion of the inside of the polishing pad by potassium permanganate in the polishing liquid, resulting in a decrease in removal rate.

As can be seen from FIG. 6, the number of scratches in example 3 and comparative example 7 is within 3, and comparative example 6 is significantly out of standard because the small pore structure makes it easier for the abrasive particles in the polishing liquid and the impurities removed by polishing to cause clogging inside the polishing pad and scratches during polishing.

As can be seen from fig. 7 to 9, the polishing pad surface of example 3 was substantially free of fuzzing, and the polishing pad surface of comparative example 1 was exposed to a large amount of fiber fuzzing because the polishing pad was free of modified polyethersulfone resin, and the polishing pad surface of comparative example 7 was somewhat fuzzed because the content of modified polyethersulfone resin was relatively small.

As can be seen from fig. 10 to 12, the polishing pad surface of example 3 was substantially free of fuzzing, and the polishing pad surface of comparative example 1 was exposed to a large amount of fiber fuzzing because the polishing pad was free of modified polyethersulfone resin, and the polishing pad surface of comparative example 7 was somewhat fuzzed because the content of modified polyethersulfone resin was relatively small.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. A polishing pad, characterized in that it comprises a base material, wherein the base material is impregnated with a resin material, wherein the raw material components of the resin material include a resin and a pore-forming agent; and the resin includes a modified polyethersulfone resin and a polyurethane resin.

2. The polishing pad according to claim 1, wherein the polyurethane resin accounts for 10% to 30% of the mass of the resin;

and/or, the modified polyethersulfone resin accounts for 70% to 90% of the mass of the resin;

and/or, the pore-forming agent accounts for 0.3-1% of the mass of the resin;

And/or, the modified polyethersulfone resin is obtained by a graft reaction of acrylic acid and polyethersulfone.

3. The polishing pad according to claim 2, characterized in that the mass ratio of the polyethersulfone to the acrylic acid is 10:

(0.1～1).

4. The polishing pad according to claim 1, wherein the pore-forming agent is selected from polyacrylic acid and/or polyvinyl alcohol;

And/or, the weight average molecular weight of the polyethersulfone resin is 10000-70000;

and/or, the 100% modulus of the polyurethane resin is 1 to 15 MPa;

And/or, the raw material component further includes a first solvent, and the first solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

5. The polishing pad according to claim 1, characterized in that the base material is selected from one of fabric, non-woven fabric or woven fabric; and/or the fiber raw material of the base material has a fiber fineness of 2.6 to 3 deniers.

6. The polishing pad according to claim 1, characterized in that the polishing pad comprises 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) compressibility of 2.0-4.0%; d) compression elasticity of 60-75%; e) air permeability of not less than 100 m ² /S; f) after being immersed in an alkaline potassium permanganate solution with a concentration of 4.5-5.5% and a pH of 8.5-9.5, the polishing pad is abraded with an H-18 ceramic grinding wheel with a load of 1-2 kg, and rotated 500-600 times at a speed of 60-75 rpm, and the wear loss is not higher than 100 mg.

7. A method for preparing a polishing pad according to any one of claims 1 to 6, characterized in that it comprises the following steps:

1) mixing the raw material components to form a homogeneous impregnation solution;

2) The base material is immersed in the immersion liquid, and then placed in a coagulation liquid for coagulation to obtain the polishing pad.

8. The preparation method according to claim 7, characterized in that the content of the modified polyethersulfone resin in the impregnation solution is 15-25wt%;

and/or, in the impregnation liquid, the content of the polyurethane resin is 2 to 10 wt %;

and/or, in the impregnation solution, the content of the pore-forming agent is 0.1-0.2 wt %;

And/or, the impregnation is followed by a rolling process;

and/or, the coagulation liquid is an aqueous solution of N,N-dimethylformamide; and/or, after the coagulation treatment, one or more treatments selected from washing, drying, grinding, and grooving are performed;

And/or, the base material has a thickness of 1.8-2.2 mm and a gram weight of 270-330 g/cm ² .

9. The preparation method according to claim 8, characterized in that the content of N,N-dimethylformamide in the coagulation liquid is 15-25wt%; and/or the speed of the rubber roller is 1-5r/min, and the roller pressure is 0.1-1Mpa.

10. Use of the polishing pad according to any one of claims 1 to 6 as a polishing pad for polishing a silicon carbide substrate in chemical mechanical polishing.