A rough polishing pad for SiC wafers and its preparation method

Abstract

This invention discloses a rough polishing pad for SiC wafers, prepared by weight of the following components: 500-1500 parts of type A wet-process resin, 200-800 parts of type B wet-process resin, 5-10 parts of aminosilane coupling agent, 5-10 parts of epoxysilane coupling agent, 1-5 parts of hindered phenolic antioxidant, 1-5 parts of phosphite antioxidant, 600-1600 parts of diluent, 150-160 parts of non-woven fabric, and 300-330 parts of adhesive. The type A wet-process resin is a wet-process resin containing polyurethane-polyurea links with a hard segment content of 54.5%-66.7%; the type B wet-process resin is a wet-process resin containing polyurethane links with a hard segment content of 35.1%-45.8%. This coarse polishing pad for SiC wafers has the advantages of high hardness and strength, good wear resistance, and good corrosion resistance. While maintaining a high removal rate and long service life, it also ensures that the SiC wafer surface has high flatness and low defect rate. This invention also provides a method for preparing this coarse polishing pad.

Description

Technical Field

[0001] This invention belongs to the technical field of SiC wafer polishing, specifically relating to a rough polishing pad for SiC wafers and its preparation method. Background Technology

[0002] Silicon carbide (SiC) is a third-generation semiconductor material with a wide bandgap of 2.3 eV. Conductive SiC is mainly used in high-voltage applications such as electric vehicles, photovoltaic power generation, and rail transportation. Among these, electric vehicles represent the largest downstream market for third-generation semiconductor materials.

[0003] One of the key steps in the SiC substrate processing flow is grinding and polishing, which mainly includes four processes: rough grinding, fine grinding, rough polishing, and fine polishing. Each process requires different types of polishing pads and polishing slurries. In recent years, with the increasingly urgent needs of the electric vehicle industry and its device market, the consumption of rough polishing pads for SiC wafers in CMP processes has also been increasing. However, most domestic SiC wafer fabs mainly use imported rough polishing pads. Domestically produced rough polishing pads generally suffer from drawbacks in CMP processes, such as low hardness and strength, poor wear resistance, poor corrosion resistance, low removal rate, insufficient flatness, high surface defect rate, and short service life.

[0004] Most existing coarse polishing pads for SiC wafers are made from a single wet-process resin. Their overall polishing performance often suffers from trade-offs, failing to adequately balance performance in areas such as lifespan, removal rate, planarization, and defect severity, thus failing to meet the high technical requirements of SiC wafer coarse polishing processes. For example, some coarse polishing pads have high hardness and strength, exhibiting good wear resistance and corrosion resistance in SiC wafer coarse polishing, but leading to insufficient flatness and increased defects on the SiC wafer surface. Other coarse polishing pads have good flexibility and compressibility, exhibiting high flatness and low defect severity in SiC wafer coarse polishing, but their poor wear resistance and corrosion resistance result in shorter lifespan and lower removal rates.

[0005] Therefore, there is an urgent need to develop a coarse polishing pad with excellent comprehensive performance, such as high hardness and strength, good wear resistance, good corrosion resistance, high removal rate, good flatness, low defect degree, and long service life, in order to solve the problem that existing polishing pads used for SiC wafers cannot take into account comprehensive performance in multiple aspects. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a coarse polishing pad for SiC wafers. By compounding a type A wet-process resin with polyurethane-polyurea linkages and high hard segment content, and a type B wet-process resin with polyurethane linkages and low hard segment content, the physicochemical properties are synergistically complementary, thereby improving the overall polishing performance of the coarse polishing pad. The resulting coarse polishing pad exhibits advantages such as high hardness and strength, good wear resistance, and good corrosion resistance. While maintaining a high removal rate and long service life, it also ensures high flatness and low defect rate on the SiC wafer surface. This invention also provides a method for preparing this coarse polishing pad.

[0007] The technical effects to be achieved by this invention are realized through the following technical aspects:

[0008] In a first aspect, the present invention provides a rough polishing pad for SiC wafers, which is prepared by weight of the following components:

[0009] 500-1500 parts of type A wet-process resin, 200-800 parts of type B wet-process resin, 5-10 parts of aminosilane coupling agent, 5-10 parts of epoxysilane coupling agent, 1-5 parts of hindered phenolic antioxidant, 1-5 parts of phosphite antioxidant, 600-1600 parts of diluent, 150-160 parts of nonwoven fabric, and 300-330 parts of adhesive backing.

[0010] The type A wet-process resin is a wet-process resin having polyurethane-polyurea links and a hard segment content of 54.5% to 66.7%; the type B wet-process resin is a wet-process resin having polyurethane links and a hard segment content of 35.1% to 45.8%.

[0011] In some embodiments, the coarse polishing pad for SiC wafers has a thickness of 1.2–1.4 mm, a hardness of 75–85 Shore A, and a compression ratio of 2%–5%.

[0012] The type A wet-process resin has a viscosity of 100,000–120,000 mPa·s and a number-average molecular weight (Mn) of 80,000–100,000 at 25°C.

[0013] The type B wet-process resin has a viscosity of 80,000–100,000 mPa·s at 25°C and a number-average molecular weight (Mn) of 60,000–80,000.

[0014] In some embodiments, the aminosilane coupling agent is selected from at least one of 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane;

[0015] The epoxy silane coupling agent is selected from at least one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane or 3-(2,3-epoxypropoxy)propyltriethoxysilane.

[0016] In some embodiments, the hindered phenolic antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, or 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene;

[0017] The phosphite antioxidant is selected from at least one of tris(2,4-di-tert-butyl)phosphite, triphenyl phosphite, or tris(nonylphenol)phosphite.

[0018] In some embodiments, the diluent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide;

[0019] The nonwoven fabric is selected from PET needle-punched nonwoven fabric or PET spunlace nonwoven fabric, with a thickness between 1.3 and 1.5 mm and a basis weight between 150 and 160 g / m². 2 between.

[0020] The adhesive backing is selected from pressure-sensitive acrylic or silicone double-sided adhesives, with a thickness between 100 and 200 μm.

[0021] In some embodiments, the type A wet-process resin is prepared from the following components in parts by weight:

[0022] 150-200 parts diisocyanate, 200-250 parts polyether diol, 150-200 parts aromatic diamine, 1-5 parts chain terminator, and 500-1500 parts diluent.

[0023] In some embodiments, the diisocyanate is selected from at least one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 4,4'-diphenylmethane diisocyanate, or 2,4'-diphenylmethane diisocyanate;

[0024] The polyether diol is selected from at least one of polypropylene glycol, polytrimethylene ether glycol, or polytetrahydrofuran glycol;

[0025] The aromatic diamine is selected from at least one of 4,4'-diamino-3,3'-dichlorodiphenylmethane, diethyltoluenediamine, or 4,4'-methylenebis(3-chloro-2,6-diethylaniline);

[0026] The chain terminator is selected from at least one of methanol, ethanol, or isopropanol.

[0027] In some embodiments, the method for synthesizing the type A wet-process resin includes the following steps:

[0028] The prepolymerization reaction involves removing water from polyether diol at 105–110°C and a negative pressure of 0.08–0.10 MPa for 1 hour, then adding diisocyanate and reacting the prepolymer in bulk at 80–90°C for 2–3 hours to obtain an isocyanate-terminated prepolymer.

[0029] Chain extension reaction: a diluent and an aromatic diamine are added sequentially to the obtained prepolymer to extend the chain, and the solution polymerization reaction is continued for 4 to 6 hours while maintaining the temperature between 80 and 90°C.

[0030] To terminate the reaction, when the polymerization reaction of the above system reaches a number average molecular weight Mn of 80,000 to 100,000, a chain terminator is added to terminate the reaction, and the material is discharged to obtain type A wet process resin.

[0031] In some embodiments, the type B wet-process resin is prepared from the following components in parts by weight:

[0032] 250-300 parts of diisocyanate, 450-500 parts of polyester diol, 20-80 parts of small molecule diol, 1-3 parts of chain terminator, and 1000-2000 parts of diluent.

[0033] In some embodiments, the diisocyanate is selected from at least one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 4,4'-diphenylmethane diisocyanate, or 2,4'-diphenylmethane diisocyanate;

[0034] The polyester diol is selected from at least one of polycaprolactone diol or polycarbonate diol;

[0035] The small molecule diol is selected from at least one of ethylene glycol, 1,4-butanediol or 1,3-propanediol;

[0036] The chain terminator is selected from at least one of methanol, ethanol, or isopropanol.

[0037] In some embodiments, the method for synthesizing the type B wet-process resin includes the following steps:

[0038] The prepolymerization reaction involves removing water from polyester diol at 110–115°C and a negative pressure of 0.08–0.10 MPa for 2 hours, then adding diisocyanate and reacting the prepolymer in bulk at 80–90°C for 2–3 hours to obtain an isocyanate-terminated prepolymer.

[0039] Chain extension reaction: a diluent and a small molecule diol are added sequentially to the obtained prepolymer to extend the chain, and the solution polymerization reaction is maintained at 80-90°C for 4-6 hours.

[0040] To terminate the reaction, when the polymerization reaction of the above system reaches a number average molecular weight Mn of 60,000 to 80,000, a chain terminator is added to terminate the reaction, and the material is discharged to obtain type B wet process resin.

[0041] In a second aspect, the present invention provides a method for preparing a coarse polishing pad for SiC wafers, the method comprising the following steps:

[0042] Step 1: Dispersing the impregnation slurry. Add type A wet process resin, type B wet process resin, aminosilane coupling agent, epoxysilane coupling agent, hindered phenol antioxidant, phosphite antioxidant and diluent to a container and disperse at a speed of 800-1000 r / min for 2-3 hours until the mixture is uniform.

[0043] Step 2: Degassing the impregnating slurry. The above-mentioned uniformly dispersed impregnating slurry is degassed for 2-3 hours under a negative pressure of 0.08-0.10 MPa. The viscosity of the impregnating slurry at 25°C is 1000-3000 mPa·s.

[0044] Step 3: Impregnation and wet coagulation. The above impregnation slurry and nonwoven fibers are thoroughly mixed to ensure uniform impregnation, and then placed in a DMF aqueous solution with a temperature of 25-45℃ and a concentration of 10%-30% for wet coagulation.

[0045] Step 4: Washing and drying. Place the solidified sample in deionized water at 40-60°C to wash off the solvent. Repeat this process more than 10 times until the solvent concentration is less than 1%. Then, dry the sample at 100-120°C for 4-6 hours to set the solvent.

[0046] Step 5: Surface polishing and grooving. Polish the shaped sample with 150-400 grit sandpaper to remove the wet resin adhering to the surface, and then grooving.

[0047] Step 6: Adhesive bonding and cutting. The grooved sample is bonded with adhesive and cut into round pieces to obtain a rough polishing pad for SiC wafers.

[0048] In summary, the present invention has at least the following advantages:

[0049] 1. The coarse polishing pad for SiC wafers provided by this invention combines a type A wet-process resin with polyurethane-polyurea linkages and a high hard segment content, and a type B wet-process resin with polyurethane linkages and a low hard segment content, so that the physicochemical properties of the resins are synergistically complementary, thereby improving the overall polishing performance of the coarse polishing pad. Compared with coarse polishing pads using a single wet-process resin, the coarse polishing pad prepared by this invention has the advantages of high hardness and strength, good wear resistance, and good corrosion resistance. While maintaining a high removal rate and a long service life, it also ensures that the SiC wafer surface has high flatness and low defect rate.

[0050] 2. The method for preparing the coarse polishing pad provided by this invention, on the one hand, involves adding a silane coupling agent in the wet impregnation process, which reacts with water molecules during solidification to generate silanol groups and forms hydrogen bonds with the interface between the wet resin and PET fibers. This significantly improves the bonding and adhesion between the PET fibers and the wet resin. In the coarse polishing process of SiC wafers, the wet resin and PET fibers are more tightly bonded and less prone to falling off, thereby improving wear resistance and resulting in a coarse polishing pad with a higher removal rate and a longer service life. On the other hand, the composite antioxidant added in the wet impregnation process can greatly improve the coarse polishing pad's resistance to oxidants in the polishing solution. In the coarse polishing process of SiC wafers, this makes the prepared coarse polishing pad less susceptible to oxidation by the polishing solution and less prone to falling off the wet resin, which can also synergistically improve the corrosion resistance and service life of the coarse polishing pad. Attached Figure Description

[0051] Figure 1 This is a simplified flowchart of the preparation method of the coarse polishing pad according to Embodiment 1 of the present invention.

[0052] Figure 2 This is a surface SEM image of the coarse polishing pad for SiC wafers prepared in Example 1 of the present invention.

[0053] Figure 3 This is a cross-sectional SEM image of the coarse polishing pad for SiC wafers prepared in Example 1 of the present invention. Detailed Implementation

[0054] To facilitate understanding of the present invention, a more comprehensive description will be given below in conjunction with the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0055] 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0056] The use of terms such as "one embodiment," "implementation," and "exemplary embodiment" in the specification means a described implementation, but not every implementation may include specific features, structures, or characteristics. Specific features, structures, or characteristics are included. Furthermore, such phrases do not necessarily refer to the same implementation. Additionally, when a specific feature, structure, or characteristic is described in connection with certain implementations, whether explicitly described or not, the effect of applying that feature, structure, or characteristic to other implementations is within the knowledge of those skilled in the art.

[0057] Values ​​expressed as ranges should be interpreted flexibly, including not only the values ​​explicitly listed as the limits of the range, but also all individual values ​​or subranges included within the range, as if each value and subrange were clearly stated. For example, a concentration range of “about 0.1% to about 5%” should be interpreted as including not only the explicitly listed values ​​of about 0.1% to about 5% by weight, but also the individual (mass) concentrations (e.g., 1%, 2%, 3%, and 4%) and subranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, and 3.3% to 4.4%) within the specified range.

[0058] As described herein, unless otherwise stated, the term "a" is used to include one or more, and the term "or" is used to refer to a non-exclusive "or". Furthermore, when terms or terms used herein are not otherwise defined, they should be understood as being for descriptive purposes only and not for limiting purposes. Additionally, all publications, patents, and patent documents mentioned in the specification are incorporated herein by reference in their entirety as if individually incorporated by reference. If there is any inconsistency between the usage in this document and those documents incorporated by reference, the usage in the cited references shall be considered supplementary to this document. In the event of irreconcilable inconsistencies, the usage herein shall prevail.

[0059] A coarse polishing pad for SiC wafers, prepared by weight of the following components:

[0060] 500-1500 parts of type A wet-process resin, 200-800 parts of type B wet-process resin, 5-10 parts of aminosilane coupling agent, 5-10 parts of epoxysilane coupling agent, 1-5 parts of hindered phenolic antioxidant, 1-5 parts of phosphite antioxidant, 600-1600 parts of diluent, 150-160 parts of nonwoven fabric, and 300-330 parts of adhesive backing.

[0061] Among them, Type A wet-process resin is a wet-process resin with polyurethane-polyurea links and a hard segment content of 54.5% to 66.7%; Type B wet-process resin is a wet-process resin with polyurethane links and a hard segment content of 35.1% to 45.8%.

[0062] The thickness of the coarse polishing pad used for SiC wafers is 1.2–1.4 mm, the hardness is 75–85 Shore A, and the compression ratio is 2%–5%.

[0063] The viscosity of type A wet-process resin at 25℃ is 100,000–120,000 mPa·s, and the number-average molecular weight Mn is 80,000–100,000.

[0064] The viscosity of type B wet-process resin at 25℃ is 80,000–100,000 mPa·s, and the number-average molecular weight (Mn) is 60,000–80,000.

[0065] Furthermore, the aminosilane coupling agent is selected from at least one of 3-aminopropyltriethoxysilane (KH-550) or 3-aminopropyltrimethoxysilane (KH-540);

[0066] The epoxy silane coupling agent is selected from at least one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560) or 3-(2,3-epoxypropoxy)propyltriethoxysilane (KH-561).

[0067] Furthermore, the hindered phenolic antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Antioxidant 1010), stearyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Antioxidant 1076) or 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (Antioxidant 1330);

[0068] The phosphite antioxidant is selected from at least one of tris(2,4-di-tert-butyl)phosphite (Antioxidant 168), triphenyl phosphite (TPP), or tris(nonylphenol) phosphite (TNP).

[0069] Furthermore, the diluent is selected from N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), or dimethyl sulfoxide (DMSO);

[0070] The nonwoven fabric is selected from PET needle-punched nonwoven fabric or PET spunlace nonwoven fabric, with a thickness between 1.3 and 1.5 mm and a basis weight between 150 and 160 g / m². 2 between.

[0071] The adhesive is selected from pressure-sensitive acrylic or silicone double-sided adhesives, with a thickness between 100 and 200 μm.

[0072] Furthermore, the type A wet-process resin is prepared from the following components in parts by weight:

[0073] 150-200 parts diisocyanate, 200-250 parts polyether diol, 150-200 parts aromatic diamine, 1-5 parts chain terminator, and 500-1500 parts diluent.

[0074] Further, the diisocyanate is selected from at least one of toluene-2,4-diisocyanate (2,4-TDI), toluene-2,6-diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4-MDI) or 2,4'-diphenylmethane diisocyanate (2,4-MDI);

[0075] The polyether diol is selected from at least one of polypropylene glycol, polytrimethylene ether glycol, or polytetrahydrofuran glycol; wherein, polypropylene glycol is preferably PPG-1000, PPG-2000, or PPG-3000; polytrimethylene ether glycol is preferably PO3G-1000, PO3G-2000, or PO3G-3000; and polytetrahydrofuran glycol is preferably PTMG-1000, PTMG-2000, or PTMG-3000.

[0076] The aromatic diamine is selected from at least one of 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA), diethyltoluenediamine (DETDA), and 4,4'-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA);

[0077] The chain terminator is selected from at least one of methanol, ethanol or isopropanol.

[0078] The synthesis method of type A wet-process resin includes the following steps:

[0079] Step 1: Prepolymerization reaction. Polyether diol is dehydrated for 1 hour at 105-110℃ and negative pressure of 0.08-0.10 MPa. Diisocyanate is added and the bulk prepolymerization reaction is carried out at 80-90℃ for 2-3 hours to obtain isocyanate-terminated prepolymer.

[0080] Step 2: Chain extension reaction. A diluent and an aromatic diamine are added sequentially to the obtained prepolymer to extend the chain, and the solution polymerization reaction is continued at 80-90°C for 4-6 hours.

[0081] Step 3: Termination of reaction. When the polymerization reaction of the above system reaches a number average molecular weight Mn of 80,000 to 100,000, add a chain terminator to terminate the reaction, discharge the material, and obtain type A wet process resin.

[0082] Type B wet-process resin is prepared from the following components in parts by weight:

[0083] 250-300 parts of diisocyanate, 450-500 parts of polyester diol, 20-80 parts of small molecule diol, 1-3 parts of chain terminator, and 1000-2000 parts of diluent.

[0084] The diisocyanate is selected from at least one of toluene-2,4-diisocyanate (2,4-TDI), toluene-2,6-diisocyanate (2,6-TDI), 4,4'-diphenylmethane diisocyanate (4,4-MDI) or 2,4'-diphenylmethane diisocyanate (2,4-MDI);

[0085] The polyester diol is selected from at least one of polycaprolactone diol or polycarbonate diol; wherein, polycaprolactone diol is preferably PCL-1000, PCL-2000, PCL-3000, and polycarbonate diol is preferably PCDL-1000, PCDL-2000, PCDL-3000.

[0086] The small molecule diol is selected from at least one of ethylene glycol (EG), 1,4-butanediol (BG) or 1,3-propanediol (PG);

[0087] The chain terminator is selected from at least one of methanol, ethanol or isopropanol.

[0088] The synthesis method of type B wet-process resin includes the following steps:

[0089] Step 1: Prepolymerization reaction. Polyester diol is dehydrated for 2 hours at 110-115℃ and negative pressure of 0.08-0.10 MPa. Diisocyanate is added and the bulk prepolymerization reaction is carried out at 80-90℃ for 2-3 hours to obtain isocyanate-terminated prepolymer.

[0090] Step 2: Chain extension reaction. Diluent and small molecule diol are added to the obtained prepolymer in sequence to extend the chain, and the solution polymerization reaction is continued at 80-90°C for 4-6 hours.

[0091] Step 3: Termination of reaction. When the above system has polymerized to a number average molecular weight Mn of 60,000 to 80,000, a chain terminator is added to terminate the reaction, and the material is discharged to obtain type B wet process resin.

[0092] The coarse polishing pad provided in this invention has the advantages of high hardness and strength, good wear resistance and good corrosion resistance. In the coarse polishing process of SiC wafers, it has strong resistance to oxidants in the coarse polishing solution. The wet resin and non-woven fibers are tightly bonded and not easy to fall off. While maintaining a high removal rate and a long service life, it can also take into account the high flatness of the SiC wafer surface and the low degree of defects.

[0093] The coarse polishing pad for SiC wafers is prepared by the following method, specifically including the following steps:

[0094] Step 1: Dispersing the impregnation slurry. Add type A wet process resin, type B wet process resin, aminosilane coupling agent, epoxysilane coupling agent, hindered phenol antioxidant, phosphite antioxidant and diluent to a container and disperse at a speed of 800-1000 r / min for 2-3 hours until the mixture is uniform.

[0095] For the synthesis methods of type A wet-process resin and type B wet-process resin, please refer to the above description.

[0096] Step 2: Degassing the impregnating slurry. The above-mentioned uniformly dispersed impregnating slurry is degassed for 2-3 hours under a negative pressure of 0.08-0.10 MPa. The viscosity of the impregnating slurry at 25°C is 1000-3000 mPa·s.

[0097] Step 3: Impregnation and wet coagulation. The above impregnation slurry and nonwoven fibers are thoroughly mixed to ensure uniform impregnation, and then placed in a DMF aqueous solution with a temperature of 25-45℃ and a concentration of 10%-30% for wet coagulation.

[0098] Step 4: Washing and drying. Place the solidified sample in deionized water at 40-60°C to wash off the solvent. Repeat this process more than 10 times until the solvent concentration is less than 1%. Then, dry the sample at 100-120°C for 4-6 hours to set the solvent.

[0099] Step 5: Surface polishing and grooving. Polish the shaped sample with 150-400 grit sandpaper to remove the wet resin adhering to the surface, and then grooving.

[0100] Step 6: Adhesive bonding and cutting. The grooved sample is bonded with adhesive and cut into round pieces to obtain a rough polishing pad for SiC wafers.

[0101] The above preparation method yields a coarse polishing pad for SiC wafers. This preparation method involves synthesizing two types of wet-process resins, Type A and Type B, with different material chain segments and hard segment contents. Then, the Type A and Type B wet-process resins are compounded, and coupling agents, antioxidants, and diluents are added and mixed and dispersed evenly to prepare an impregnation slurry. After vacuum degassing, the slurry is thoroughly mixed with non-woven fibers for even impregnation. After solidification, washing, drying, polishing, and grooving, the slurry is finally coated with adhesive and cut into round pieces to obtain the coarse polishing pad for SiC wafers.

[0102] Example 1

[0103] This embodiment provides a rough polishing pad for SiC wafers, prepared by weight of the following components: 1000 parts of type A wet-process resin, 500 parts of type B wet-process resin, 8 parts of aminosilane coupling agent, 7 parts of epoxysilane coupling agent, 3 parts of hindered phenolic antioxidant, 2 parts of phosphite antioxidant, 1100 parts of diluent, 155 parts of non-woven fabric, and 315 parts of adhesive backing. The rough polishing pad has a thickness of 1.3 mm, a hardness of 80 Shore A, and a compression ratio of 3.5%.

[0104] In this embodiment, the type A wet-process resin is a wet-process resin with polyurethane-polyurea links, a hard segment content of 60.3%, a viscosity of 112,500 mPa·s at 25°C, and a number-average molecular weight Mn of 92,800.

[0105] Type B wet-process resin is a wet-process resin with polyurethane links, a hard segment content of 40.7%, a viscosity of 96300 mPa·s at 25°C, and a number-average molecular weight (Mn) of 71700.

[0106] Preferably, the aminosilane coupling agent is 3-aminopropyltriethoxysilane (KH-550), the epoxysilane coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), the hindered phenolic antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (Antioxidant 1010), the phosphite antioxidant is tris(2,4-di-tert-butyl)phenyl phosphite (Antioxidant 168), the diluent is N,N-dimethylformamide (DMF), and the nonwoven fabric is PET needle-punched nonwoven fabric with a thickness of 1.4 mm and a basis weight of 155 g / m². 2 The backing adhesive is a pressure-sensitive acrylic double-sided adhesive with a thickness of 150μm.

[0107] In this embodiment, the type A wet-process resin is prepared from the following components in parts by weight: 180 parts diisocyanate, 230 parts polyether diol, 170 parts aromatic diamine, 3 parts chain terminator, and 1000 parts diluent.

[0108] Preferably, the diisocyanate is toluene-2,4-diisocyanate (2,4-TDI), the polyether diol is polypropylene glycol (preferably PPG-1000), the aromatic diamine is 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA), and the chain terminator is methanol.

[0109] The synthesis method of this type A wet-process resin includes the following steps:

[0110] Step 1: Prepolymerization reaction. Polyether diol is dehydrated for 1 hour at 105-110℃ and negative pressure of 0.08-0.10 MPa. Diisocyanate is added and the bulk prepolymerization reaction is carried out at 80-90℃ for 2-3 hours to obtain isocyanate-terminated prepolymer.

[0111] Step 2: Chain extension reaction. A diluent and an aromatic diamine are added sequentially to the obtained prepolymer to extend the chain, and the solution polymerization reaction is continued at 80-90°C for 4-6 hours.

[0112] Step 3: Termination of reaction. When the polymerization reaction of the above system reaches a number average molecular weight Mn of 80,000 to 100,000, add a chain terminator to terminate the reaction, discharge the material, and obtain type A wet process resin.

[0113] In this embodiment, the type B wet-process resin is prepared from the following components in parts by weight: 280 parts diisocyanate, 480 parts polyester diol, 50 parts small molecule diol, 2 parts chain terminator, and 1500 parts diluent.

[0114] Preferably, the diisocyanate is 4,4'-diphenylmethane diisocyanate (4,4-MDI), the polyester diol is polycaprolactone diol (preferably PCL-2000), the small molecule diol is 1,4-butanediol (BG), and the chain terminator is ethanol.

[0115] The synthesis method of this type B wet-process resin includes the following steps:

[0116] Step 1: Prepolymerization reaction. Polyester diol is dehydrated for 2 hours at 110-115℃ and negative pressure of 0.08-0.10 MPa. Diisocyanate is added and the bulk prepolymerization reaction is carried out at 80-90℃ for 2-3 hours to obtain isocyanate-terminated prepolymer.

[0117] Step 2: Chain extension reaction. Diluent and small molecule diol are added to the obtained prepolymer in sequence to extend the chain, and the solution polymerization reaction is continued at 80-90°C for 4-6 hours.

[0118] Step 3: Termination of reaction. When the above system has polymerized to a number average molecular weight Mn of 60,000 to 80,000, a chain terminator is added to terminate the reaction, and the material is discharged to obtain type B wet process resin.

[0119] The aforementioned rough polishing pad for SiC wafers is prepared by the following method, as described in the reference. Figure 1 Specifically, it includes the following steps:

[0120] Step 1: Dispersing the impregnation slurry. Add type A wet process resin, type B wet process resin, aminosilane coupling agent, epoxysilane coupling agent, hindered phenol antioxidant, phosphite antioxidant and diluent to a container and disperse at a speed of 800-1000 r / min for 2-3 hours until the mixture is uniform.

[0121] Step 2: Degassing the impregnating slurry. The above-mentioned uniformly dispersed impregnating slurry is degassed for 2-3 hours under a negative pressure of 0.08-0.10 MPa. The viscosity of the impregnating slurry at 25°C is 1000-3000 mPa·s.

[0122] Step 3: Impregnation and wet coagulation. The above impregnation slurry and nonwoven fibers are thoroughly mixed to ensure uniform impregnation, and then placed in a DMF aqueous solution with a temperature of 25-45℃ and a concentration of 10%-30% for wet coagulation.

[0123] Step 4: Washing and drying. Place the solidified sample in deionized water at 40-60°C to wash off the solvent. Repeat this process more than 10 times until the solvent concentration is less than 1%. Then, dry the sample at 100-120°C for 4-6 hours to set the solvent.

[0124] Step 5: Surface polishing and grooving. Polish the shaped sample with 150-400 grit sandpaper to remove the wet resin adhering to the surface, and then grooving.

[0125] Step 6: Adhesive bonding and cutting. The grooved sample is bonded with adhesive and cut into round pieces to obtain a rough polishing pad for SiC wafers.

[0126] Please refer to the surface SEM images and cross-sectional SEM images of the rough polishing pads for SiC wafers prepared in this embodiment. Figure 2 and Figure 3 .

[0127] Example 2

[0128] This embodiment provides a rough polishing pad for SiC wafers, prepared by weight of the following components: 500 parts of type A wet-process resin, 200 parts of type B wet-process resin, 5 parts of aminosilane coupling agent, 5 parts of epoxysilane coupling agent, 1 part of hindered phenolic antioxidant, 1 part of phosphite antioxidant, 600 parts of diluent, 150 parts of non-woven fabric, and 300 parts of adhesive backing. The rough polishing pad has a thickness of 1.2 mm, a hardness of 75 Shore A, and a compression ratio of 5.0%.

[0129] In this embodiment, the type A wet-process resin is a wet-process resin with polyurethane-polyurea segments, a hard segment content of 54.5%, a viscosity of 120,000 mPa·s at 25°C, and a number-average molecular weight Mn of 100,000.

[0130] Type B wet-process resin is a wet-process resin with polyurethane links, a hard segment content of 35.1%, a viscosity of 100,000 mPa·s at 25°C, and a number-average molecular weight (Mn) of 80,000.

[0131] Preferably, the aminosilane coupling agent is 3-aminopropyltrimethoxysilane (KH-540), the epoxysilane coupling agent is 3-(2,3-epoxypropoxy)propyltriethoxysilane (KH-561), the hindered phenolic antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester (Antioxidant 1076), the phosphite antioxidant is triphenyl phosphite (TPP), the diluent is N-methylpyrrolidone (NMP), and the nonwoven fabric is PET spunlace nonwoven fabric with a thickness of 1.3 mm and a basis weight of 150 g / m². 2 The adhesive backing is a pressure-sensitive silicone double-sided adhesive with a thickness of 100μm.

[0132] In this embodiment, the type A wet-process resin is prepared by weight of the following components: 150 parts diisocyanate, 250 parts polyether diol, 150 parts aromatic diamine, 1 part chain terminator, and 500 parts diluent.

[0133] Preferably, the diisocyanate is toluene-2,6-diisocyanate (2,6-TDI), the polyether diol is polytrimethylene ether diol (preferably PO3G-3000), the aromatic diamine is diethyltoluene diamine (DETDA), and the chain terminator is ethanol.

[0134] The synthesis method of this type A wet-process resin is the same as in Example 1.

[0135] In this embodiment, the type B wet-process resin is prepared from the following components in parts by weight: 250 parts diisocyanate, 500 parts polyester diol, 20 parts small molecule diol, 1 part chain terminator, and 1000 parts diluent.

[0136] Preferably, the diisocyanate is 2,4'-diphenylmethane diisocyanate (2,4-MDI), the polyester diol is polycarbonate diol (preferably PCDL-1000), the small molecule diol is ethylene glycol (EG), and the chain terminator is isopropanol.

[0137] The synthesis method of this type B wet-process resin is the same as in Example 1.

[0138] The preparation method of the rough polishing pad for SiC wafers in this embodiment is the same as in Embodiment 1. During the preparation process, the raw materials required for each step are as per the weight proportions in this embodiment.

[0139] Example 3

[0140] This embodiment provides a rough polishing pad for SiC wafers, prepared by weight of the following components: 1500 parts of type A wet-process resin, 800 parts of type B wet-process resin, 10 parts of aminosilane coupling agent, 10 parts of epoxysilane coupling agent, 5 parts of hindered phenolic antioxidant, 5 parts of phosphite antioxidant, 1600 parts of diluent, 160 parts of non-woven fabric, and 330 parts of adhesive backing. The rough polishing pad has a thickness of 1.4 mm, a hardness of 85 Shore A, and a compression ratio of 2.0%.

[0141] In this embodiment, the type A wet-process resin is a wet-process resin with polyurethane-polyurea segments, a hard segment content of 66.7%, a viscosity of 100,000 mPa·s at 25°C, and a number-average molecular weight Mn of 80,000.

[0142] Type B wet-process resin is a wet-process resin with polyurethane links, a hard segment content of 45.8%, a viscosity of 80,000 mPa·s at 25°C, and a number-average molecular weight (Mn) of 60,000.

[0143] Preferably, the aminosilane coupling agent is 3-aminopropyltriethoxysilane (KH-550), the epoxysilane coupling agent is 3-(2,3-epoxypropoxy)propyltrimethoxysilane (KH-560), the hindered phenolic antioxidant is 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (Antioxidant 1330), the phosphite antioxidant is tris(nonylphenol) phosphite (TNP), the diluent is dimethyl sulfoxide (DMSO), and the nonwoven fabric is PET needle-punched nonwoven fabric with a thickness of 1.5 mm and a basis weight of 160 g / m². 2 The backing adhesive is a pressure-sensitive acrylic double-sided adhesive with a thickness of 200μm.

[0144] In this embodiment, the type A wet-process resin is prepared by weight of the following components: 200 parts diisocyanate, 200 parts polyether diol, 200 parts aromatic diamine, 5 parts chain terminator, and 1500 parts diluent.

[0145] Preferably, the diisocyanate is 4,4'-diphenylmethane diisocyanate (4,4-MDI), the polyether diol is polytetrahydrofuran diol (preferably PTMG-2000), the aromatic diamine is 4,4'-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA), and the chain terminator is isopropanol.

[0146] The synthesis method of this type A wet-process resin is the same as in Example 1.

[0147] In this embodiment, the type B wet-process resin is prepared from the following components in parts by weight: 300 parts diisocyanate, 450 parts polyester diol, 80 parts small molecule diol, 3 parts chain terminator, and 2000 parts diluent.

[0148] Preferably, the diisocyanate is toluene-2,6-diisocyanate (2,6-TDI), the polyester diol is polycaprolactone diol (preferably PCL-3000), the small molecule diol is 1,3-propanediol (PG), and the chain terminator is methanol.

[0149] The synthesis method of this type B wet-process resin is the same as in Example 1.

[0150] The preparation method of the rough polishing pad for SiC wafers in this embodiment is the same as in Embodiment 1. During the preparation process, the raw materials required for each step are as per the weight proportions in this embodiment.

[0151] Example 4

[0152] This embodiment provides a rough polishing pad for SiC wafers, prepared by weight of the following components: 1200 parts of type A wet-process resin, 600 parts of type B wet-process resin, 7 parts of aminosilane coupling agent, 8 parts of epoxysilane coupling agent, 2 parts of hindered phenolic antioxidant, 3 parts of phosphite antioxidant, 1000 parts of diluent, 155 parts of non-woven fabric, and 315 parts of adhesive backing. The rough polishing pad has a thickness of 1.3 mm, a hardness of 79 Shore A, and a compression ratio of 4.3%.

[0153] In this embodiment, the type A wet-process resin is a wet-process resin with polyurethane-polyurea links, a hard segment content of 61.4%, a viscosity of 114560 mPa·s at 25°C, and a number-average molecular weight Mn of 91830.

[0154] Type B wet-process resin is a wet-process resin with polyurethane links, a hard segment content of 41.3%, a viscosity of 97,600 mPa·s at 25°C, and a number-average molecular weight (Mn) of 73,590.

[0155] Preferably, the aminosilane coupling agent is 3-aminopropyltrimethoxysilane (KH-540), the epoxysilane coupling agent is 3-(2,3-epoxypropoxy)propyltriethoxysilane (KH-561), the hindered phenolic antioxidant is β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester (Antioxidant 1076), the phosphite antioxidant is triphenyl phosphite (TPP), the diluent is N,N-dimethylformamide (DMF), and the nonwoven fabric is PET spunlace nonwoven fabric with a thickness of 1.4 mm and a basis weight of 155 g / m². 2The adhesive backing is a pressure-sensitive silicone double-sided adhesive with a thickness of 150μm.

[0156] In this embodiment, the type A wet-process resin is prepared from the following components in parts by weight: 170 parts diisocyanate, 220 parts polyether diol, 180 parts aromatic diamine, 2 parts chain terminator, and 1000 parts diluent.

[0157] Preferably, the diisocyanate is 2,4'-diphenylmethane diisocyanate (2,4-MDI), the polyether diol is polytrimethylene ether diol (preferably PO3G-2000), the aromatic diamine is 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA), and the chain terminator is ethanol.

[0158] The synthesis method of this type A wet-process resin is the same as in Example 1.

[0159] In this embodiment, the type B wet-process resin is prepared from the following components in parts by weight: 270 parts diisocyanate, 470 parts polyester diol, 60 parts small molecule diol, 2 parts chain terminator, and 1400 parts diluent.

[0160] Preferably, the diisocyanate is toluene-2,4-diisocyanate (2,4-TDI), the polyester diol is polycarbonate diol (preferably PCDL-3000), the small molecule diol is 1,4-butanediol (BG), and the chain terminator is isopropanol.

[0161] The synthesis method of this type B wet-process resin is the same as in Example 1.

[0162] The preparation method of the rough polishing pad for SiC wafers in this embodiment is the same as in Embodiment 1. During the preparation process, the raw materials required for each step are as per the weight proportions in this embodiment.

[0163] Comparative Example 1

[0164] The only difference between Comparative Example 1 and Example 1 is that the same amount of Type B wet-process resin was replaced with Type A wet-process resin, while all other aspects remained the same as in Example 1.

[0165] Comparative Example 2

[0166] The only difference between Comparative Example 2 and Example 1 is that the A-type wet-process resin is replaced with an equal weight of the B-type wet-process resin, while all other aspects remain the same as in Example 1.

[0167] Comparative Example 3

[0168] The only difference between Comparative Example 3 and Example 1 is that the aminosilane coupling agent has 0 parts by weight and the epoxysilane coupling agent has 0 parts by weight; all other aspects are the same as in Example 1.

[0169] Comparative Example 4

[0170] The only difference between Comparative Example 4 and Example 1 is that the hindered phenolic antioxidant is 0 parts by weight and the phosphite antioxidant is 0 parts by weight; all other aspects are the same as in Example 1.

[0171] Test case

[0172] The physical properties and polishing performance of the coarse polishing pads for SiC wafers prepared in Examples 1-4 and Comparative Examples 1-4 were tested. Among them:

[0173] The test method for number-average molecular weight Mn refers to the national standard GB / T 27843-2011, and the gel permeation chromatograph (GPC) model is Agilent 1260 Infinity II.

[0174] The tensile strength test method refers to the national standard GB / T 1040.3-2006, and the electronic universal testing machine model is ZwickRoll 5kN Allround table top.

[0175] The hardness test method refers to the national standard GB / T 2411-2008. The Shore A hardness tester model is Teclock GS-709G.

[0176] The test method for compression ratio refers to GB / T 30709—2014, and the Dynamic Thermomechanical Analyzer (DMA) model is TADMA850.

[0177] The test method for abrasion resistance is in accordance with GB / T 5478-2008, and the abrasion testing machine model is Taber 1700.

[0178] The corrosion resistance test method is as follows: Place the sample to be tested in a mixed aqueous solution of potassium permanganate and sulfuric acid (10wt% potassium permanganate, 10wt% sulfuric acid, and 80wt% deionized water) until the sample falls off or breaks down within the limit time.

[0179] The testing methods for polishing removal rate, lifespan, surface roughness, and surface defects are as follows:

[0180] Remove the release paper from the 24-inch rough polishing pad sample and attach it to the high-precision surface polishing machine. The polishing fluid is SC-A1 with a flow rate of 30cc / min. The wafer is a 6-inch 4H-SiC wafer (Si surface fine polishing). The high-precision surface polishing machine is YM-610SP with a pressure of 2.5psi and a grinding disc speed of 30rpm (the workpiece is placed on the grinding disc and rotates). The dressing disc is a diamond disk.

[0181] The removal rate is an average value calculated by recording the removal rate during the polishing process using an optical film thickness gauge (KLA Filmetrics F50).

[0182] Surface roughness was measured using a 3D surface profiler (CHOTEST Superview W1).

[0183] The number of surface defects is the total number of surface defects (including particles, scratches, bumps, pits, etc.) larger than 100nm detected by the surface defect detection equipment (KLA-Tencor Candela CS20).

[0184] Lifetime is the limit of time during which the polishing pad is continuously subjected to chemical mechanical polishing (CMP) tests until the polishing removal rate decreases significantly.

[0185] The physical properties and polishing performance of the coarse polishing pads for SiC wafers prepared in Examples 1-4 and the coarse polishing pads prepared in Comparative Examples 1-4 are shown in Table 1.

[0186] Table 1. Physical properties and polishing performance test results of the coarse polishing pads prepared in Examples 1-4 and Comparative Examples 1-4.

[0187]

[0188] Based on the test results of the physical properties and polishing performance of the coarse polishing pads in the above embodiments and comparative examples, it is shown that:

[0189] 1. Compared with Comparative Examples 1-2 (using a single wet process resin), Examples 1-4, by compounding a type A wet process resin with polyurethane-polyurea links and a high hard segment content and a type B wet process resin with polyurethane links and a low hard segment content, can effectively improve the surface flatness (reduced roughness) and defect rate (reduced number of defects), and also improve its hardness, strength and wear resistance, while effectively maintaining a high removal rate and without affecting its service life.

[0190] 2. Compared with Comparative Example 3, the addition of silane coupling agent in the wet impregnation process in Examples 1 to 4 can significantly improve the bonding and adhesion between PET fibers and wet resin. The wet resin and PET fibers are more tightly bonded, and the prepared coarse polishing pad has better wear resistance (reduced wear). The resin is less likely to fall off in the coarse polishing process of SiC wafers, thereby effectively improving its removal rate and service life.

[0191] 3. Compared with Comparative Example 4, Examples 1 to 4 added a composite antioxidant to the wet impregnation process. The rough polishing pads prepared by these examples can greatly improve the resistance to oxidants in the polishing slurry, effectively slow down the corrosion of the rough polishing pads by the polishing slurry, and thus effectively improve their corrosion resistance (increased corrosion resistance time) and service life in the rough polishing process of SiC wafers.

[0192] The above description is merely an example and illustration of the structure of this invention, and while the description is specific and detailed, it should not be construed as limiting the scope of this invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this invention, and these obvious substitutions all fall within the protection scope of this invention.

Claims

1. A rough polishing pad for SiC wafers, characterized in that, It is prepared from the following components in parts by weight: 500-1500 parts of type A wet-process resin, 200-800 parts of type B wet-process resin, 5-10 parts of aminosilane coupling agent, 5-10 parts of epoxysilane coupling agent, 1-5 parts of hindered phenolic antioxidant, 1-5 parts of phosphite antioxidant, 600-1600 parts of diluent, 150-160 parts of nonwoven fabric, and 300-330 parts of adhesive backing. Wherein, the type A wet-process resin is a wet-process resin having polyurethane-polyurea links and a hard segment content of 54.5% to 66.7%; the type B wet-process resin is a wet-process resin having polyurethane links and a hard segment content of 35.1% to 45.8%. The coarse polishing pad used for SiC wafers has a thickness of 1.2~1.4mm, a hardness of 75~85 Shore A, and a compression ratio of 2%~5%. The type A wet-process resin has a viscosity of 100,000~120,000 mPa·s and a number-average molecular weight Mn of 80,000~100,000 at 25°C. The type B wet-process resin has a viscosity of 80,000~100,000 mPa·s at 25°C and a number-average molecular weight (Mn) of 60,000~80,000.

2. The rough polishing pad for SiC wafers according to claim 1, characterized in that, The aminosilane coupling agent is selected from at least one of 3-aminopropyltriethoxysilane or 3-aminopropyltrimethoxysilane; The epoxy silane coupling agent is selected from at least one of 3-(2,3-epoxypropoxy)propyltrimethoxysilane or 3-(2,3-epoxypropoxy)propyltriethoxysilane.

3. The rough polishing pad for SiC wafers according to claim 1, characterized in that, The hindered phenolic antioxidant is selected from at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, or 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene; The phosphite antioxidant is selected from at least one of tris(2,4-di-tert-butyl)phosphite, triphenyl phosphite, or tris(nonylphenol)phosphite.

4. The rough polishing pad for SiC wafers according to claim 1, characterized in that, The diluting solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide; The nonwoven fabric is selected from PET needle-punched nonwoven fabric or PET spunlace nonwoven fabric, with a thickness between 1.3 and 1.5 mm and a basis weight between 150 and 160 g / m². 2 between; The adhesive is selected from pressure-sensitive acrylic or silicone double-sided adhesives, with a thickness between 100 and 200 μm.

5. The rough polishing pad for SiC wafers according to claim 1, characterized in that, The type A wet-process resin is prepared from the following components in parts by weight: 150-200 parts diisocyanate, 200-250 parts polyether diol, 150-200 parts aromatic diamine, 1-5 parts chain terminator, and 500-1500 parts diluent.

6. The rough polishing pad for SiC wafers according to claim 5, characterized in that, The diisocyanate is selected from at least one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 4,4'-diphenylmethane diisocyanate or 2,4'-diphenylmethane diisocyanate; The polyether diol is selected from at least one of polypropylene glycol, polytrimethylene ether glycol, or polytetrahydrofuran glycol; The aromatic diamine is selected from at least one of 4,4'-diamino-3,3'-dichlorodiphenylmethane, diethyltoluenediamine, or 4,4'-methylenebis(3-chloro-2,6-diethylaniline); The chain terminator is selected from at least one of methanol, ethanol, or isopropanol.

7. The rough polishing pad for SiC wafers according to claim 5, characterized in that, The method for synthesizing the type A wet-process resin includes the following steps: Prepolymerization reaction: Polyether diol is dehydrated for 1 hour at 105~110℃ and negative pressure 0.08~0.10Mpa, and diisocyanate is added and the bulk prepolymerization reaction is carried out at 80~90℃ for 2~3 hours to obtain isocyanate-terminated prepolymer. Chain extension reaction: a diluent and an aromatic diamine are added sequentially to the obtained prepolymer to extend the chain, and the solution polymerization reaction is continued at 80-90°C for 4-6 hours. To terminate the reaction, when the polymerization reaction of the above system reaches a number average molecular weight Mn of 80,000 to 100,000, a chain terminator is added to terminate the reaction, and the material is discharged to obtain type A wet process resin.

8. The rough polishing pad for SiC wafers according to claim 1, characterized in that, The type B wet-process resin is prepared from the following components in parts by weight: 250-300 parts of diisocyanate, 450-500 parts of polyester diol, 20-80 parts of small molecule diol, 1-3 parts of chain terminator, and 1000-2000 parts of diluent.

9. The rough polishing pad for SiC wafers according to claim 8, characterized in that, The diisocyanate is selected from at least one of toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 4,4'-diphenylmethane diisocyanate or 2,4'-diphenylmethane diisocyanate; The polyester diol is selected from at least one of polycaprolactone diol or polycarbonate diol; The small molecule diol is selected from at least one of ethylene glycol, 1,4-butanediol or 1,3-propanediol; The chain terminator is selected from at least one of methanol, ethanol, or isopropanol.

10. The rough polishing pad for SiC wafers according to claim 8, characterized in that, The synthesis method of the type B wet-process resin includes the following steps: The prepolymerization reaction involves removing water from polyester diol at 110-115℃ and a negative pressure of 0.08-0.10 MPa for 2 hours, then adding diisocyanate and reacting the prepolymer in bulk at 80-90℃ for 2-3 hours to obtain an isocyanate-terminated prepolymer. Chain extension reaction: a diluent and a small molecule diol are added sequentially to the obtained prepolymer to extend the chain, and the solution polymerization reaction is maintained at 80~90℃ for 4~6h. To terminate the reaction, when the above polymerization reaction reaches a number average molecular weight Mn between 60,000 and 80,000, a chain terminator is added to terminate the reaction, and the material is discharged to obtain type B wet process resin.

11. A method for preparing a coarse polishing pad, used to prepare the coarse polishing pad for SiC wafers as described in any one of claims 1-10, characterized in that, Includes the following steps: Step 1: Dispersing the impregnation slurry. Add type A wet process resin, type B wet process resin, aminosilane coupling agent, epoxysilane coupling agent, hindered phenol antioxidant, phosphite antioxidant and diluent to a container and disperse at a speed of 800~1000 r / min for 2~3 hours until the mixture is uniform. Step 2: Degassing the impregnating slurry. Degas the evenly dispersed impregnating slurry under a negative pressure of 0.08~0.10 MPa for 2~3 hours. The viscosity of the impregnating slurry at 25℃ is 1000~3000 mPa·S. Step 3: Impregnation and wet coagulation. The impregnation slurry and nonwoven fibers are thoroughly mixed to ensure uniform impregnation, and then placed in a DMF aqueous solution with a temperature of 25~45℃ and a concentration of 10%~30% for wet coagulation. Step 4: Washing and drying. Place the solidified sample in deionized water at 40-60℃ to wash off the solvent. Repeat this process more than 10 times until the solvent concentration is less than 1%. Then, dry the sample at 100-120℃ for 4-6 hours to set the sample. Step 5: Surface polishing and grooving. Use 150-400 grit sandpaper to polish the shaped sample flat, remove the wet resin adhering to the surface, and then grooving. Step 6: Adhesive bonding and cutting. The grooved sample is bonded with adhesive and cut into round pieces to obtain a rough polishing pad for SiC wafers.

Images