Polishing pad and method for manufacturing the same

Abstract

To provide a polishing pad having improved abrasion resistance.SOLUTION: The polishing pad has a polishing layer includes, as a polishing layer, a polyurethane resin sheet including a plurality of tear-shaped air bubble, which includes polyurethane resin and specific polyether polycarbonate diol as a film formation auxiliary agent.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polishing pad used for polishing semiconductor devices and the like, and a method for manufacturing the same.

Background Art

[0002] Since flatness is required for the surfaces of materials such as silicon, glass substrates for hard disks, mother glass for thin-film liquid crystal displays, semiconductor wafers, and semiconductor devices, free abrasive polishing using a polishing pad is performed. The free abrasive method is a method of polishing the processed surface of the workpiece while supplying a slurry (polishing liquid) containing abrasive grains between the polishing pad and the workpiece. For a polishing pad for a semiconductor device, pores for holding abrasive grains, hardness for maintaining the flatness of the semiconductor device surface, and elasticity for preventing scratches on the semiconductor device surface are required on the surface of the polishing pad. As a polishing pad that meets these requirements, a polishing pad having a polishing layer with a polyurethane resin or the like as a matrix is used. With the miniaturization of the structure of semiconductor devices, further reduction of polishing scratches is required. As a physical property of the pad, the softer it is, the less likely it is to generate polishing scratches. However, during dressing, the pad is easily scraped off, resulting in poor wear resistance and a decrease in polishing efficiency. In order to perform polishing processing stably for a long time, it is necessary to suppress the wear of the polishing surface. Therefore, means for improving the wear resistance while using a soft resin sheet are required. For example, Patent Document 1 describes that in a polishing cloth including a base material and a resin sheet having a silver surface by a wet film-forming method on the base material, by setting the content of solid components other than the resin (carbon black) in the resin sheet to 62.5 mg or less per 1 g of the resin sheet, the wear resistance of the polishing surface increases and the wear amount decreases. However, the technique of Patent Document 1 reduces the amount of solid components other than the resin and increases the resin ratio, and since the components contained in the resin solution composition have not been changed conventionally, the wear resistance of the polishing pad is still not sufficient.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Japanese Patent Publication No. 2013-188830 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present invention aims to provide an abrasive pad having improved wear resistance compared to conventional pads, and a method for manufacturing the same. [Means for solving the problem]

[0005] To solve the aforementioned problems, the inventors conducted thorough research and discovered that adding polyether polycarbonate diol as a film-forming aid during the manufacturing of a polyurethane resin sheet used as the polishing layer of a polishing pad improves the wear resistance of the polishing pad, leading to the present invention. In other words, the present invention provides the following: [1] A polishing pad comprising a polyurethane resin sheet containing multiple teardrop-shaped bubbles as an polishing layer, The polishing pad wherein the polyurethane resin sheet comprises a polyurethane resin and a polyether polycarbonate diol as a film-forming aid. [2] The polishing pad according to [1], wherein the polyether polycarbonate diol is a polyether polycarbonate diol represented by the following formula (A). In the above formula (A), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is an integer from 2 to 30, and m is an integer from 1 to 20. Multiple Rs may be the same or different. [3] The polishing pad according to [1] or [2], wherein the number average molecular weight of the polyether polycarbonate diol is 200 to 5000. [4] A step of applying a resin solution composition containing polyurethane resin, polyether polycarbonate diol as a film-forming aid, and a solvent to a film-forming substrate, and A process to form a wet-formed polyurethane resin sheet by immersing a film-forming substrate coated with the resin solution composition in a solidification solution and solidifying the resin solution composition, A method for manufacturing an abrasive pad according to any one of [1] to [3] above, including the method described above. [Effects of the Invention]

[0006] The present invention provides a polishing pad with improved wear resistance compared to conventional pads and a method for manufacturing the same. Furthermore, the present invention provides a polishing pad having a soft polyurethane resin sheet as the polishing layer, which can reduce polishing scratches, and which has improved wear resistance. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a cross-sectional SEM image taken after cutting the polyurethane resin sheet 1 of Example 1 in the thickness direction. [Figure 2] Figure 2 shows a cross-sectional SEM image of the polyurethane resin sheet 2 of Example 2, taken after cutting it in the thickness direction. [Figure 3] Figure 3 shows a cross-sectional SEM image of the polyurethane resin sheet 3 of Comparative Example 1, taken after cutting it in the thickness direction. [Modes for carrying out the invention]

[0008] The following describes embodiments for carrying out the present invention. <<Polishing pad>> The polishing pad of the present invention comprises a polyurethane resin sheet containing a plurality of teardrop-shaped bubbles as an polishing layer, and the polyurethane resin sheet is characterized in that it contains a polyurethane resin and a polyether polycarbonate diol as a film-forming aid.

[0009] <Polyurethane resin sheet> In the present invention, the polishing pad is a polishing pad that includes a polyurethane resin sheet as an polishing layer. The polyurethane resin sheet of the present invention has a plurality of teardrop-shaped bubbles. The teardrop-shaped bubbles are intended to be characteristic bubbles (which are anisotropic and have a structure in which the diameter increases from the top (the side in contact with the workpiece) to the bottom of the resin sheet) that are typically formed inside the polyurethane resin sheet by a wet film formation method in which a resin solution composition is formed in a solidification bath and dried, and are distinguished from the approximately spherical bubbles formed by a dry molding method in which a curable composition containing a prepolymer is poured into a mold and cured. There are no particular restrictions on the type of polyurethane resin used to form the polyurethane resin sheet; it can be selected from a variety of polyurethane resins according to the intended use. For example, polyester-based, polyether-based, or polycarbonate-based resins can be used. Examples of polyester resins include polymers of polyester polyols, such as ethylene glycol or butylene glycol, and adipic acid, and diisocyanates such as diphenylmethane-4,4'-diisocyanate. Examples of polyether-based resins include polymers of polyether polyols such as polytetramethylene ether glycol and polypropylene glycol with isocyanates such as diphenylmethane-4,4'-diisocyanate. Examples of polycarbonate-based resins include polymers of polycarbonate polyols and isocyanates such as diphenylmethane-4,4'-diisocyanate. These resins may be commercially available resins such as "Crisbon" manufactured by DIC Corporation, "Samplen" manufactured by Sanyo Chemical Industries, Ltd., or "Rezamin" manufactured by Dainichi Seika Kogyo Co., Ltd., or a resin with the desired properties may be manufactured in-house.

[0010] The polyurethane resin is the main component of the polyurethane resin sheet as the matrix. Being the main component means being contained in an amount of 50% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more of all the resins constituting the polyurethane resin sheet. The polyurethane resin sheet of the present invention may contain other resins other than the polyurethane resin as a part of the matrix, but when containing such other resins, it can be contained in an amount that does not impair the effects of the present invention, and it is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably not contained.

[0011] In the present invention, the polyurethane resin sheet containing a plurality of teardrop-shaped bubbles means a polyurethane resin sheet formed by a wet film-forming method. The wet film-forming method is a method in which the resin to be formed into a film is dissolved in an organic solvent, and the resin solution is applied to a sheet-shaped substrate and then passed through a coagulating liquid to coagulate the resin. The wet film-formed polyurethane resin sheet generally has a plurality of teardrop-shaped (teardrop-shaped) bubbles (a shape having anisotropy and a structure in which the diameter is larger from the polishing surface of the polishing pad toward the bottom). Therefore, the wet film-formed polyurethane resin sheet can be paraphrased as a polyurethane resin sheet having a plurality of teardrop-shaped bubbles.

[0012] The polyurethane resin preferably has a specific modulus. The modulus is an index representing the hardness of the resin, and is a value obtained by dividing the load applied when a non-foamed resin sheet is stretched by 100% (stretched to twice the original length) by the cross-sectional area (hereinafter, sometimes referred to as 100% modulus). The higher this value, the harder the resin. The polyurethane resin of the present invention preferably has a 100% modulus of 1 to 20 MPa, more preferably 3 to 18 MPa, even more preferably 5 to 15 MPa, and even more preferably 6 to 10 MPa. When the 100% modulus is within the above range, it is suitable for use in the application of polishing a wafer having a wiring metal because defects can be reduced.

[0013] <Film-forming aid> A film-forming aid refers to an agent that has the effect of suppressing shrinkage and the like of a resin sheet when producing a resin sheet by a wet film-forming method and assisting stable film-forming properties (film-forming stability). By using a film-forming aid, foaming and coagulation regeneration (desolvation) can be controlled, and a resin sheet having a desired foamed shape and physical properties (mechanical properties) can be obtained. At least a part of the film-forming aid may elute when substitution between the solvent in the resin solution composition and the coagulation liquid occurs. The elution property of the film-forming aid can be adjusted, for example, by the chemical structure and molecular weight of the film-forming aid, etc. A film-forming aid that is difficult to dissolve in the coagulation liquid (hydrophobic additive) tends to remain in the resin sheet in a large amount. The polyurethane resin sheet of the present invention contains polyether polycarbonate diol as a film-forming aid. Polyether polycarbonate diol is a diol compound having a polyether part and a polycarbonate part. Preferably, it is a compound having a polyether part derived from polyalkylene ether glycol, more preferably derived from polytetramethylene ether glycol. The polyether polycarbonate diol is more preferably a polyether polycarbonate diol represented by the following formula (A). TIFF0007888421000002.tif27170

[0014] In the above formula (A), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is an integer of 2 to 30, and m is an integer of 1 to 20. In the formula (A), a plurality of Rs may be the same or different. R is a parameter related to the ratio of ether bonds in the molecule (the distance between ether bonds). When the number of carbon atoms is less than 2, the hydrophilicity may increase too much due to the increase in the ratio of ether bonds in the molecule, and conversely, the film-forming property may deteriorate. When the number of carbon atoms exceeds 10, the ratio of ether bonds decreases, and the effect of the present invention may not be exhibited. Preferably, R is a linear or branched alkylene group having 3 to 6 carbon atoms, more preferably a butylene group having 4 carbon atoms or a 2-methylbutylene group having 5 carbon atoms. n is a parameter related to the proportion of carbonate bonds within the molecule (distance between carbonate bonds). If n is less than 2, the proportion of carbonate bonds within the molecule increases, leading to stronger cohesive force and potentially preventing uniform dispersion within the polyurethane resin matrix. If n exceeds 30, the proportion of carbonate bonds decreases, potentially preventing the effects of the present invention from being realized. n is preferably between 2 and 10, and more preferably between 2 and 5. m is a parameter related to the molecular weight of the polyether polycarbonate diol. If m is less than 1, it may easily dissolve in the coagulation solution during film formation, and the effects of the present invention may not be achieved. If it exceeds 20, the viscosity will increase, and it may not be uniformly dispersed in the polyurethane resin matrix. m is preferably 2 to 10, and more preferably 2 to 7.

[0015] The number-average molecular weight of the polyoxyalkylene glycol used in the production of polyether polycarbonate diol is a value related to the n parameter, preferably 100 to 1500, more preferably 150 to 1000, and even more preferably 200 to 850. The number-average molecular weight of the polyether polycarbonate diol is a value related to the m parameter, preferably 200 to 5000, more preferably 500 to 3000, and even more preferably 800 to 2500. In this specification, the number-average molecular weight of the structural units derived from the polytetramethylene ether glycol and the polyether polycarbonate diol can be measured as the molecular weight in terms of polystyrene based on gel permeation chromatography (GPC) under the following conditions. <Measurement conditions> Column: Shodex® OHpak SB-802.5HQ (manufactured by Showa Denko Corporation) Mobile phase: 5mM LiBr / DMF Flow rate: 0.5mL / min (26kg / cm 2 ) Oven: 60℃ Detector: RI 40℃ Sample volume: 20 μL

[0016] There are no particular restrictions on the amount of polyether polycarbonate diol contained in the resin sheet, but it is preferably contained in the range of 0.1 to 20% by mass relative to the mass of the resin sheet, more preferably 0.5 to 15% by mass, even more preferably 1 to 10% by mass, and still more preferably 3 to 8% by mass.

[0017] (Other ingredients) The polyurethane resin sheet of the present invention may or may not contain, in addition to the above-mentioned components, pigments, other film-forming aids other than polyether polycarbonate diol, agents for adjusting chemical properties, etc., to the extent that the effects of the present invention are not impaired. When pigments are included, carbon black is preferred from the viewpoint of improving abrasion resistance and adjusting the size and quantity (number) of teardrop-shaped bubbles to stabilize foam formation. There are no particular restrictions on the amount of carbon black contained in the resin sheet, but it is preferably 1 to 30% by mass relative to the mass of the resin sheet, more preferably 5 to 25% by mass, even more preferably 7 to 20% by mass, and even more preferably 9 to 15% by mass.

[0018] Other film-forming aids include, for example, hydrophilic additives that promote the formation of teardrop-shaped bubbles, and hydrophobic additives that stabilize the wet coagulation of polyurethane resins. Examples of hydrophilic additives include anionic surfactants such as sodium lauryl sulfate, carboxylates, sulfonates, sulfate esters, and phosphate esters, and nonionic surfactants such as hydrophilic esters, ethers, ester-ethers, and amides. Examples of hydrophobic additives include nonionic surfactants with alkyl chains having 3 or more carbon atoms, more specifically, polyoxyethylene alkyl ethers, polyoxypropylene alkyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, perfluoroalkyl ethylene oxide adducts, glycerin fatty acid esters, and propylene glycol fatty acid esters. When hydrophilic or hydrophobic additives are included, the hydrophilic or hydrophobic additives are preferably present in an amount of 0.01 to 10 parts by mass, more preferably 0.1 to 9 parts by mass, even more preferably 0.5 to 8 parts by mass, and even more preferably 1 to 7 parts by mass per 100 parts by mass of polyurethane resin (solids) contained in the resin solution composition. Examples of agents used to modify the chemical properties of resin sheets include water repellents, antioxidants, light stabilizers, antiblocking agents, and antistatic agents, which have the effect of altering the chemical properties of the resin sheet.

[0019] In the present invention, the polyurethane resin sheet is the polishing layer of the polishing pad, that is, a layer having a surface (polishing surface) that comes into contact with the workpiece to be polished, such as a semiconductor device, when polishing the workpiece. The polishing layer in the polishing pad of the present invention is made of a polyurethane resin sheet obtained by wet film deposition. There are no particular restrictions on the thickness of the polishing layer, but for example, it can be used in the range of 0.3 to 3.0 mm, preferably 0.4 to 2.0 mm, and more preferably 0.5 to 1.5 mm.

[0020] <<Manufacturing method for polishing pads>> The present invention provides a method for manufacturing an abrasive pad, comprising the steps of: applying a resin solution composition containing a polyurethane resin, a polyether polycarbonate diol as a film-forming aid, and a solvent to a film-forming substrate; and forming a wet-film-formed polyurethane resin sheet by immersing the film-forming substrate coated with the resin solution composition in a solidification solution to solidify the resin solution composition.

[0021] <Step of applying the resin solution composition to the film-forming substrate> A resin solution composition containing polyurethane resin, polyether polycarbonate diol as a film-forming aid, and a solvent is applied to a film-forming substrate. The polyurethane resin and polyether polycarbonate diol are as described above. The polyether polycarbonate diol is preferably included in the resin solution composition in an amount of 0.1 to 20 parts by mass per 100 parts by mass of polyurethane resin (solids), more preferably 1 to 15 parts by mass, even more preferably 3 to 10 parts by mass, and still more preferably 5 to 8 parts by mass. The solvent used in the resin solution composition for forming the polyurethane resin sheet of the present invention is not particularly limited as long as it can dissolve the polyurethane resin and is miscible with water. Examples include N,N-dimethylformamide (DMF), methyl ethyl ketone, N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and acetone. Among these, DMF or DMAc are preferably used. The organic solvent is preferably included in the resin solution composition in an amount such that the solid content concentration of the resin solution composition is preferably 10 to 50% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 35% by mass. If the concentration is within the above range, the resin solution composition will have appropriate fluidity and can be uniformly applied to the film-forming substrate in the subsequent coating process. The coating process involves continuously applying the resin solution composition to the film-forming substrate using a knife coater, reverse coater, or the like, to ensure a nearly uniform application. The coating thickness (amount) of the resin solution composition is adjusted by controlling the gap (clearance) between the knife coater or the film-forming substrate. The film-forming substrate can be any substrate commonly used in this art without particular limitations. Examples include flexible polymer films such as polyester films and polyolefin films, and nonwoven fabrics impregnated and fixed with elastic resin. Among these, polyester films are preferred.

[0022] <Wet film formation process> Wet film formation is performed by immersing a film-forming substrate coated with the above-described resin solution composition in a solidification solution to solidify the resin solution composition. As the coagulation solution, water, a mixed solution of water and a polar organic solvent such as DMF can be used. Examples of polar organic solvents include water-miscible organic solvents used to dissolve polyurethane resin, such as DMF, DMAc, THF, DMSO, NMP, and acetone. The concentration of the polar organic solvent in the mixed solvent is preferably 0 to 20% by mass. Among these, water or a mixed solution of water and DMF is preferred as the coagulation solution, and water is more preferred. There are no particular restrictions on the temperature of the coagulation solution or the immersion time; for example, immersion at 10-60°C (preferably 15-50°C) for 5-120 minutes is sufficient. In the solidification solution, a dense skin layer is first formed at the interface between the resin solution composition and the solidification bath. Subsequently, the solvent in the resin solution composition is replaced by the solidification solution through the skin layer, and the polyurethane resin is solidified and regenerated in a sheet-like form on the film-forming substrate, forming a polyurethane resin sheet with multiple teardrop-shaped bubbles inside. After solidifying in a solidification bath, the sheet-like polyurethane resin obtained is peeled off the film-forming substrate, or without peeling, and then washed and dried. The cleaning process removes any organic solvents remaining in the polyurethane resin sheet. Water is a common cleaning solution used for this process. After washing, the polyurethane resin sheet is dried. The drying process can be carried out using conventional methods; for example, it can be dried in a dryer at 80-150°C for about 5-60 minutes.

[0023] In the method for manufacturing the polishing pad of the present invention, the polishing surface and / or the surface opposite to the polishing surface of the polyurethane resin sheet may be polished (buffed) as needed. Furthermore, grooves, embossing, and / or holes (punching) may be applied to the polishing surface of the polyurethane sheet, and a base material may be bonded to the polyurethane sheet. In addition, a light-transmitting portion may be provided on the polyurethane sheet and / or the polishing pad. There are no particular restrictions on the grinding method, and grinding can be done using known methods. Specifically, grinding with sandpaper is one example. There are no particular restrictions on the shape of the grooves and embossing; for example, grid-type, concentric circle, and radial shapes can be used. When bonding multiple substrates together to form a multilayer structure, the layers can be bonded and fixed together using double-sided tape or adhesive, applying pressure as needed. There are no particular restrictions on the double-sided tape or adhesive used in this process; any known double-sided tape or adhesive in this field can be arbitrarily selected and used. [Examples]

[0024] <Example 1> A resin solution composition was obtained by mixing 100 parts by mass of an ester-based polyurethane resin solution with a 100% modulus of 7.8 MPa (solid content concentration of 30% by mass), 60 parts by mass of DMF, 3 parts by mass of water, 16.5 parts by mass of carbon black dispersion (solid content concentration of 25% by mass (carbon black equivalent amount of 4.2 parts by mass)), 0.5 parts by mass of a hydrophilic additive (sodium lauryl sulfate), and 2 parts by mass of polyether polycarbonate diol (1) represented by formula (A) with a number average molecular weight of 1000, containing structural units derived from polytetramethylene ether glycol with a number average molecular weight of 250 (in formula (A), R is an n-butylene group, average n=3.2, average m=2.7). Next, a polyethylene terephthalate (PET) film was prepared as the film-forming substrate. The resin solution composition was applied to it using a knife coater, and the film was immersed in a solidification bath (the solidification liquid was water) to solidify the resin solution composition. After that, the film-forming substrate was peeled off, washed, and dried to obtain a polyurethane resin sheet 1. This polyurethane resin sheet 1 contained multiple so-called teardrop-shaped bubbles obtained by wet film formation. Subsequently, the skin layer was buffed to open up the surface, and a PET film was bonded to the side of the polyurethane resin sheet 1 opposite to the buffed side. Then, the polyurethane resin sheet 1 was embossed from the buffed side using a grid-shaped mold, and double-sided tape was bonded to the side of the PET film opposite to the side bonded to the polyurethane resin sheet 1 to obtain the polishing pad of Example 1.

[0025] <Example 2> Polyurethane resin sheet 2 was obtained in the same manner as in Example 1, except that 2 parts by mass of polyether polycarbonate diol (1) in the resin solution composition of Example 1 was replaced with 2 parts by mass of polyether polycarbonate diol (2) represented by formula (A) with a number average molecular weight of 2000, which contains structural units derived from polytetramethylene ether glycol with a number average molecular weight of 250 (in formula (A), R is an n-butylene group, average n=3.2, average m=6.3). This polyurethane resin sheet 2 contained multiple so-called teardrop-shaped bubbles obtained by wet film formation. The polishing pad of Example 2 was obtained from the polyurethane resin sheet 2 in the same manner as in Example 1.

[0026] <Comparative Example 1> A polyurethane resin sheet 3 was obtained in the same manner as in Example 1, except that 2 parts by mass of polyether polycarbonate diol (1) in the resin solution composition of Example 1 was replaced with 0.6 parts by mass of a copolymer of ethylene oxide and propylene oxide (molar ratio of ethylene oxide:propylene oxide = 4:1) having a number average molecular weight of 10800, and a polishing pad for Comparative Example 1 was obtained. In Comparative Example 1, 0.6 parts by mass was used to obtain better results.

[0027] The number-average molecular weights of the structural units derived from the polytetramethylene ether glycol and the polyether polycarbonate diol were measured as polystyrene-equivalent molecular weights based on GPC under the following conditions. <Measurement conditions> Column: Shodex® OHpak SB-802.5HQ (manufactured by Showa Denko Corporation) Mobile phase: 5mM LiBr / DMF Flow rate: 0.5mL / min (26kg / cm 2 ) Oven: 60℃ Detector: RI 40℃ Sample volume: 20 μL

[0028] <Evaluation Test> (Taper wear amount) For measuring wear, a friction wear test was conducted using a Taber abrasion tester conforming to JIS K 6902 under the following test conditions, and the change in thickness of the polyurethane resin sheet was measured. Specifically, a polyurethane resin sheet was punched out to a diameter of 125 mm, a hole was made in the center, and the test specimen was left to stand for 1 hour in an environment of 20 ± 3°C and 65 ± 5% humidity to prepare a test specimen. Then, the test specimen was set in the Taber abrasion tester, and an abrasion test was conducted under the following test conditions. For the amount of wear, the thickness of the test specimen before the abrasion test was measured at four arbitrary locations and the average value was calculated. This test specimen was then subjected to the test, removed after 4000 rpm, and the thickness of the worn test specimen was measured at four arbitrary locations and the average value was calculated. The amount of thickness reduction was determined from the difference between the two. The thickness was measured using a thickness gauge, and measurements were taken to the nearest 0.001 mm. Furthermore, the contact position of the sandpaper attached to the abrasion wheel with respect to the polyurethane resin test specimen was set so that the circumference of the sandpaper attached to the abrasion wheel contacted the polyurethane resin test specimen (radius 62.5 mm) at a position 33 to 20 mm inward from the circumference (the center of the abrasion wheel contacted the polyurethane resin test specimen 26.5 mm inward from the circumference).

[0029] (Test conditions) Taber abrasion tester: No. 502 Taber abrasion tester (manufactured by MIZ Testing Machine Co., Ltd.) Polyurethane resin sheet rotation speed: 70 rpm Weight: 500g Wear wheels (pair): Inner diameter 15.88 mm x Outer diameter 50.0 mm x Thickness 13.0 mm Sandpaper: #180 grit sandpaper (attached to the wear wheel)

[0030] TIFF0007888421000003.tif47119

[0031] In Examples 1 and 2, where polyether polycarbonate diol was used as a film-forming aid, foaming was suppressed, density increased, and abrasion resistance improved compared to the comparative example. It was also confirmed that abrasion resistance could be imparted even to polyether polycarbonate diols with different molecular weights. Comparing Example 1 and Example 2, Example 2 showed greater abrasion than Example 1 despite having a higher density. Therefore, it is thought that the improvement in abrasion resistance was not only due to the increase in density, but also due to the unique properties of polyether polycarbonate diol. Although the mechanism of action is not clear, polyether polycarbonate diol has a structure in which carbonate bonds and ether bonds coexist, and it is presumed that this unique structure influenced the degree of foaming and phase separation structure of the polyurethane resin sheet formed by wet film deposition.

Claims

1. A polishing pad comprising a polyurethane resin sheet containing multiple teardrop-shaped bubbles as an abrasive layer, The polishing pad wherein the polyurethane resin sheet comprises a polyurethane resin and a polyether polycarbonate diol as a film-forming aid.

2. The polishing pad according to claim 1, wherein the polyether polycarbonate diol is a polyether polycarbonate diol represented by the following formula (A). In the above formula (A), R represents a divalent hydrocarbon group having 2 to 10 carbon atoms, n is an integer from 2 to 30, and m is an integer from 1 to 20. Multiple Rs may be the same or different.

3. The polishing pad according to claim 1, wherein the number average molecular weight of the polyether polycarbonate diol is 200 to 5000.

4. A step of applying a resin solution composition containing polyurethane resin, polyether polycarbonate diol as a film-forming aid, and a solvent to a film-forming substrate, and A process to form a wet-formed polyurethane resin sheet by immersing a film-forming substrate coated with the resin solution composition in a solidification solution and solidifying the resin solution composition, A method for manufacturing an abrasive pad according to any one of claims 1 to 3, including the method described in any one of claims 1 to 3.

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