Holding pad, method for manufacturing holding pad and method for manufacturing polishing workpiece

Abstract

To provide a holding pad which can secure a sufficiently long product life even if subjected to polishing using a strong oxidation agent.SOLUTION: A holding pad includes a resin sheet having a holding surface for holding a polished object and a joint surface different from the holding surface, wherein the resin sheet contains a polyurethane resin, a water-repellent agent, and a hydrolysis inhibitor.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a holding pad, a method for manufacturing a holding pad, and a method for manufacturing a polished workpiece. [Background technology]

[0002] Currently, power devices using semiconductors such as SiC, GaN, etc. are known. Chemical Mechanical Polishing (CMP) technology is used to put these semiconductor substrates into practical use.

[0003] The above-mentioned semiconductors generally have high hardness and excellent corrosion resistance, so that in performing CMP, a holding pad for holding the workpiece, a polishing pad, and a solution containing a strong oxidizing agent such as potassium permanganate as a polishing liquid are used in combination (see, for example, Patent Document 1).Addition of an oxidizing agent to the polishing liquid has also been considered for the purpose of improving the polishing rate and processing accuracy in mirror finish polishing of III-V compound semiconductors (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6106535 [Patent Document 2] International Publication No. 2022 / 024726 Summary of the Invention [Problem to be solved by the invention]

[0005] In CMP, a holding pad (suede pad) with a holding surface having a polyurethane resin sheet containing multiple teardrop-shaped bubbles is widely used. A typical example of this suede pad is a resin sheet made of polyurethane resin with bubbles formed in a three-dimensional mesh pattern. Due to this structure, the polishing liquid containing a strong oxidizing agent penetrates from the holding surface or sides and remains inside the holding pad, and the resin sheet is hydrolyzed to a low molecular weight, causing a significant deterioration in physical properties and a tendency to shorten the product life.

[0006] The present invention has been made in consideration of the above circumstances, and has an object to provide a holding pad etc. that can ensure a sufficiently long product life even when used in polishing using a strong oxidizing agent. [Means for solving the problem]

[0007] As a result of intensive research by the present inventors to solve the above problems, they discovered that the above problems could be solved by a holding pad containing a specific component, and thus completed the present invention.

[0008] That is, the present invention includes the following aspects. [1] A holding pad including a resin sheet having a holding surface for holding an object to be polished and a bonding surface different from the holding surface, The resin sheet comprises a polyurethane resin, a water repellent, and a hydrolysis inhibitor. [2] The holding pad according to [1], wherein the content of carbon black in the resin sheet is 10 mass % or less. [3] The holding pad according to [1] or [2], wherein the water repellent agent comprises at least one selected from the group consisting of a fluorine-based water repellent agent, a silicone-based water repellent agent, and a hydrocarbon-based water repellent agent. [4] The holding pad according to any one of [1] to [3], wherein the water repellent agent contains a polyurethane resin having a perfluoroalkyl group. [5] The holding pad according to any one of [1] to [4], wherein the hydrolysis inhibitor contains at least one selected from the group consisting of carbodiimide compounds, oxazoline compounds, and epoxy compounds. [6] The holding pad according to any one of [1] to [5], wherein the hydrolysis inhibitor contains a carbodiimide compound having a carbodiimide equivalent of 50 or more and 1,000 or less. [7] The holding pad according to any one of [1] to [6], wherein the resin sheet contains air bubbles that are interconnected in a three-dimensional network pattern. [8] The holding pad according to any one of [1] to [7], wherein the resin sheet is formed by a wet film forming method. [9] The resin sheet is A layer A is disposed on the support surface side and includes first pores; A layer B is disposed on the joining surface side and includes second pores; a layer C disposed between the layer A and the layer B and including teardrop-shaped bubbles larger than the first pores and the second pores; The holding pad according to any one of [1] to [8],

[10] The holding pad according to [9], wherein the carbon black content in the resin sheet is 10 mass % or less.

[11] The density of the resin sheet is 0.15 g / cm 3 More than 0.35g / cm 3 is as follows: The holding pad according to any one of [1] to

[10] , wherein the resin sheet has a Shore A hardness of 15 degrees or more and 50 degrees or less.

[12] preparing a resin solution containing a polyurethane resin, a solvent, a water repellent, and a hydrolysis inhibitor; applying the resin solution to a surface of a film-forming substrate; A step of coagulating and regenerating the resin in the resin solution to form a precursor sheet; obtaining a resin sheet from the precursor sheet; Including, The method for producing a holding pad, wherein the resin sheet contains the polyurethane resin, the water repellent, and the hydrolysis inhibitor.

[13] A method for producing a polished product, comprising a polishing step of polishing a workpiece held on the holding surface of a holding pad described in any one of [1] to

[11] in the presence of a polishing liquid containing a strong oxidizing agent to obtain a polished product. Effect of the Invention

[0009] According to the present invention, it is possible to provide a holding pad or the like which can ensure a sufficiently long product life even when subjected to polishing using a strong oxidizing agent. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a cross-sectional view showing a schematic example of a holding pad according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a schematic example of a resin sheet in the holding pad according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Below, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail, but the present invention is not limited to this embodiment, and various modifications are possible without departing from the gist of the present invention.

[0012] [Holding pad] The holding pad of this embodiment is a holding pad comprising a resin sheet having a holding surface for holding an object to be polished and a bonding surface different from the holding surface, the resin sheet containing a polyurethane resin, a water repellent, and a hydrolysis inhibitor. Since the holding pad of this embodiment is configured in this way, it can ensure a sufficiently long product life even when used for polishing using a strong oxidizing agent.

[0013] FIG. 1 is a schematic cross-sectional view showing an example of the holding pad of this embodiment. The holding pad 110 includes a resin sheet (hereinafter, simply referred to as "resin sheet") 112 containing a polyurethane resin, a water repellent, and a hydrolysis inhibitor, and a base material 114, which are laminated in this order. The resin sheet 112 and the base material 114 are directly or indirectly bonded to each other, and in this example, the resin sheet 112 and the base material 114 are bonded to each other via an adhesive layer 116. Note that the base material 114 and the adhesive layer 116 are optional configurations in the holding pad of this embodiment, and the holding pad of this embodiment is not limited to an embodiment having the base material 114 and the adhesive layer 116. That is, the resin sheet 112 alone can be used as the holding pad of this embodiment.

[0014] (Resin sheet) 2, the resin sheet 112 has a holding surface S1 for holding an object to be polished, and a bonding surface S2 different from the holding surface S1, and a base material 114 such as a PET film can be disposed on the bonding surface S2. The surface of the base material 114 opposite to the resin sheet 112 can be fixed to a holding platen (not shown) via an adhesive or the like.

[0015] The resin sheet has a holding surface for holding the object to be polished. That is, at least one surface of the holding pad of this embodiment corresponds to the surface of the resin sheet of this embodiment, and the surface of the resin sheet becomes the holding surface for holding the object to be polished during polishing of this embodiment. The holding pad of this embodiment can hold the object to be polished by the interaction between the holding surface and the surface of the object to be polished, for example, by pressing the object to be polished against the holding surface with an appropriate amount of water. The holding surface may be designed to be slightly larger than the object to be polished so that it is easy to hold the object to be polished. Furthermore, the holding surface may be configured to hold multiple objects to be polished at the same time.

[0016] The density (bulk density) of the resin sheet is not particularly limited, but is preferably 0.15 g / cm at 25° C. 3 More than 0.35g / cm 3 It is preferable that the density is 0.15 g / cm or less. 3When the polishing pressure is 0.35 g / cm or more, sinking is suppressed even when the polishing pressure is high, and a higher degree of flatness of the polished object tends to be achieved. 3 When the polishing amount is equal to or less than this, the occurrence of polishing scratches on the surface of the polished object due to the impact during polishing tends to be more effectively suppressed. The density can be measured based on the method described in the Examples below. The density can be adjusted to the above range, for example, by adopting the manufacturing method of the holding pad of this embodiment described later, etc. For example, in the manufacturing process of the resin sheet of this embodiment, the density of the resin sheet tends to be increased by reducing the amount of foaming agent such as water, inert gas, hollow fine particles, etc. in the case of the molding method, and by reducing the amount of hydrophilic activator that promotes foaming in the case of the wet film forming method.

[0017] The Shore A hardness of the resin sheet is not particularly limited, but is preferably 15 degrees or more and 50 degrees or less, and more preferably 20 degrees or more and 45 degrees or less. When the Shore A hardness is 15 degrees or more, even when processed at a high polishing pressure, sinking is suppressed, and the polished object tends to be flattened to a higher degree. In addition, when the Shore A hardness is 50 degrees or less, the occurrence of polishing scratches on the polished object surface due to impact during polishing tends to be more suppressed. Furthermore, since the Shore A hardness is within the above range, the holding pad of this embodiment tends to be applicable to a wide range of polished objects, from InP substrates, which are considered to be brittle substrates among compound semiconductors, to SiC and GaN, which are so-called difficult-to-cut materials. The Shore A hardness is measured at 25° C. in accordance with JIS K 7311. More specifically, a plurality of samples are stacked to a total thickness of 4.5 mm or more, and the measurement is performed using a Shore A durometer. The Shore A hardness can be controlled, for example, by adjusting the type and composition of the resin used in the resin sheet, and the amount of additives (eg, carbon black) that can be used when producing the resin sheet.

[0018] In this embodiment, from the viewpoint of achieving a higher degree of planarization of the object to be polished and from the viewpoint of suppressing the occurrence of polishing scratches on the surface of the object to be polished due to the impact during polishing, the density of the resin sheet is set to 0.15 g / cm 3 More than 0.35g / cm 3 or less, and it is particularly preferable that the Shore A hardness of the resin sheet is 15 degrees or more and 50 degrees or less. The density and Shore A hardness can be controlled within the above-mentioned ranges, for example, by the above-mentioned methods.

[0019] The thickness of the resin sheet is not particularly limited, but is preferably 0.2 mm or more and 5.0 mm or less, and more preferably 0.3 mm or more and 2.0 mm or less. When the thickness of the resin sheet is 0.2 mm or more, the amount of compression deformation is improved, so that the holding performance (adhesion) of the object to be polished is improved, and the impact to the object to be polished during polishing is absorbed, so that defects such as breakage tend to be reduced. In addition, when the thickness of the resin sheet is 5.0 mm or less, the deterioration of flatness and the decrease in polishing rate caused by the amount of compression deformation being too high tend to be suppressed. The thickness of the resin sheet is measured in accordance with the measurement method described in JIS K 6505. That is, the resin sheet is subjected to an initial load of 1 cm in the thickness direction. 2 This is the thickness when a load of 100g is applied (stressed).

[0020] The compressibility of the resin sheet is not particularly limited, but is preferably 1% to 30%, more preferably 3% to 20%. When the compressibility is within the above range, the occurrence of polishing scratches on the surface of the workpiece caused by the impact during polishing is more suppressed, and the polishing rate tends to be more improved. The compression ratio can be controlled, for example, by adjusting the size, number, shape, etc. of air bubbles in the resin sheet. The compression ratio is measured according to the following method.

[0021] The compressive elastic modulus of the resin sheet is not particularly limited, but is preferably 50% or more and 100% or less, and more preferably 80% or more and 100% or less. When the compressive elastic modulus is within the above range, the occurrence of polishing scratches on the surface of the object to be polished due to the impact during polishing tends to be more suppressed. The compressive elastic modulus can be controlled, for example, by adjusting the type and composition of the resin used in the resin sheet. The compressive elastic modulus is measured according to the following method.

[0022] The compressibility and compressive modulus of the resin sheet are determined using a Shopper-type thickness gauge (pressure surface: circle with a diameter of 1 cm) in accordance with JIS L 1021. Specifically, at room temperature, an initial load is applied for 30 seconds from an unloaded state, and a thickness t0 is measured. Then, a final load is applied from the thickness t0 state, and the sheet is left for 1 minute, after which a thickness t1 is measured. Furthermore, all loads are removed from the thickness t1 state, the sheet is left for 1 minute, and the initial load is again applied for 30 seconds, after which a thickness t0' is measured. From these values, the compressibility and compressive modulus are calculated using the following formula: Compression ratio (%) = (t0-t1) / t0 x 100 Compressive elastic modulus (%) = (t0'-t1) / (t0-t1) x 100 In this case, the initial load is 100g / cm 2 , final load is 1120g / cm 2 Let us assume that.

[0023] When the resin sheet is formed by a wet film forming method, the 100% modulus of the polyurethane resin constituting the resin sheet is preferably 1 MPa or more and 30 MPa or less, more preferably 5 MPa or more and 20 MPa or less. When the 100% modulus is within the above range, the occurrence of polishing scratches on the surface of the object to be polished due to the impact during polishing is more suppressed, and the polishing rate tends to be more improved. The 100% modulus is an index of the hardness of the resin, and is the value obtained by dividing the load applied when a non-foamed resin sheet is stretched 100% (to twice the original length) by the unit area. The larger this value, the harder the resin is.

[0024] The resin sheet preferably has a plurality of bubbles (not shown) therein, and more preferably contains bubbles that are connected in a three-dimensional mesh pattern. Such a plurality of bubbles may be formed by a wet film-forming method or a molding method. An example of the wet film-forming method is, but is not limited to, a method in which a resin solution in which a resin such as a polyurethane resin is dissolved in a water-miscible organic solvent is applied to a sheet-shaped film-forming substrate, and then the organic solvent is replaced with water in a water-based coagulation liquid to obtain a resin sheet. An example of the molding method is, but is not limited to, a method in which a resin sheet is obtained by reacting various known polyisocyanate compounds, polyol compounds, and polyamine compounds. Generally, resin sheets formed by wet film-forming method tend to be more susceptible to hydrolysis in terms of resin composition and specific surface area than those formed by molding method. Therefore, resin sheets formed by wet film-forming method tend to be more susceptible to the strong oxidizing agent used in polishing, and therefore the effect of long-term use in this embodiment tends to be more prominent. In the case where the resin sheet is formed by a wet film forming method, a typical structure of the resin sheet includes a layer A arranged on the holding surface side and including a first pore, a layer B arranged on the joining surface side and including a second pore, and a layer C arranged between the layer A and the layer B and including teardrop-shaped bubbles larger than the first pore and the second pore. The layers A and B are also called skin layers, and dense pores are formed therein. The surfaces of the layers A and B have fine flatness. The first pores and the second pores can be formed, for example, by adding a pore-forming agent during film formation of the resin sheet. Between the layers A and B (inside the resin sheet), it is preferable to arrange a layer C having a pore diameter larger than the pores of the layers A and B and a rounded triangular cross-sectional pore (teardrop-shaped bubbles; not shown) formed along the thickness direction of the resin sheet. The teardrop-shaped bubbles are preferably formed to be smaller on the holding surface S1 side than on the joining surface S2 side. In the resin sheet, pores (fine bubbles; not shown) larger than the first pores and second pores in layers A and B and smaller than the teardrop-shaped bubbles may be formed in layers A, B, and C. In addition, it is preferable that at least one of the first pores, second pores, teardrop-shaped bubbles, and fine bubbles are interconnected in a three-dimensional network shape. In this embodiment, although not limited thereto, such a structure tends to be easily obtained when the resin sheet is formed by a wet film formation method. In this embodiment, the resin sheet having layers A and B may be applied to the holding pad, or may be applied to the holding pad after removing either or both of layers A and B by grinding (buffing), but it is preferable to apply the resin sheet having layers A and B to the holding pad. When layers A and / or B are removed, the surface of layer C is exposed, and openings are exposed on the surface of the resin sheet, which tends to allow the polishing liquid to easily penetrate through the openings. In particular, from the viewpoint of suppressing deterioration of the polyurethane resin when the polishing liquid is a strong oxidizing agent, it is preferable to apply the resin sheet having layers A and B to the holding pad. When the resin sheet is formed by a molding method, pores having a circular or elliptical (approximately spherical) cross section may be formed and approximately uniformly distributed inside the resin sheet.

[0025] The resin sheet is not particularly limited as long as it contains a polyurethane resin, and for example, the resin sheet may contain 80% by mass or more and 100% by mass or less of polyurethane resin relative to the total amount (100% by mass). The resin sheet preferably contains 85% by mass or more and 100% by mass or less of polyurethane resin relative to the total amount (100% by mass), more preferably 90% by mass or more and 100% by mass or less, and even more preferably 90% by mass or more and 95% by mass or less.

[0026] The polyurethane resin may be, for example, polyester polyurethane resin, polyether polyurethane resin, polycarbonate polyurethane resin, etc., depending on the type of polyol component contained, and these may be used alone or in combination of two or more. Among these, polyester polyurethane resin is preferred because it is easy to form teardrop-shaped bubbles that promote circulation of polishing liquid by storing and discharging the polishing liquid during polishing. In general, the resin sheet formed by polyester polyurethane resin is easily affected by the strong oxidizing agent used in polishing, and therefore, when polyester polyurethane resin is used, the effect of long-term use in this embodiment tends to be significant. The polyurethane resin may be a carbodiimide-modified polyurethane resin, but if it does not contain a hydrolysis inhibitor separate from the carbodiimide-modified polyurethane resin, the effect derived from the hydrolysis inhibitor in the present embodiment described below cannot be obtained, so the hydrolysis inhibitor is considered to be contained in addition to the carbodiimide-modified polyurethane resin.

[0027] The polyurethane resin may be synthesized by a conventional method, or may be a commercially available product. Examples of commercially available products include CRISBON (manufactured by DIC Corporation, product name), SANPREN (manufactured by Sanyo Chemical Industries, Ltd., product name), and REZAMIN (manufactured by Dai-Nippon Seika Kogyo Co., Ltd., product name). The polyurethane resin may be used alone or in combination of two or more kinds.

[0028] The resin sheet may contain other resins such as polysulfone resin and / or polyimide resin in addition to polyurethane resin. The polysulfone resin may be synthesized by a conventional method or may be commercially available. An example of a commercially available product is Udel (manufactured by Solvay Advanced Polymers, trade name). The polyimide resin may be synthesized by a conventional method or may be commercially available. An example of a commercially available product is AURUM (manufactured by Mitsui Chemicals, trade name).

[0029] The resin sheet contains a water repellent in addition to the polyurethane resin. The water repellent is an agent that, when contained in the resin sheet, has the effect of improving the water repellency of the surface of the resin sheet. Here, the water repellency can be, for example, an index of the contact angle between the polishing surface and water. By containing the water repellent, the resin sheet can suppress the penetration of the polishing liquid containing a strong oxidizing agent into the inside of the holding pad. In particular, when the resin sheet is manufactured by a wet film forming method and has air bubbles connected in a three-dimensional network shape inside, it is possible to suppress the penetration of the strong oxidizing agent into the air bubbles inside the resin sheet while allowing the polished object to be held by the surface tension of water. Whether the resin sheet contains a water repellent agent can be confirmed by using a known analysis method such as elemental analysis.

[0030] Examples of water repellents include fluorine-based water repellents, silicone-based water repellents, and hydrocarbon-based water repellents. Among these, fluorine-based water repellents (water repellents containing fluorine atoms) are preferred from the viewpoints of chemical resistance, uniformity of mixing with polyurethane resin, etc. The water repellents are used alone or in combination of two or more.

[0031] Examples of fluorine-based water repellents include compounds having a perfluoroalkyl group, preferably containing a polyurethane resin having a perfluoroalkyl group, and more preferably having a structure derived from a fluorotelomer represented by the following formula (1). This is presumably because the bond energy between C—F bonds is 116 kcal / mol, giving the compound particularly high stability, which prevents the compound from bonding (adhesion) with other molecules (although the cause is not limited to this). Rf-RX (1) In formula (1), Rf represents a perfluoroalkyl group having 3 to 8 carbon atoms, preferably 4 to 8, more preferably 6 to 8, and even more preferably 6. R represents an alkylene group having 1 to 6 carbon atoms, preferably 2 to 4, and more preferably 2. X represents a functional group, and examples of the functional group include a hydroxy group, CH2=CHC(=O)CO-, H(OCH2CH2) x O-, YSO3- (Y represents a hydrogen atom or NH4), and preferably a hydroxy group.

[0032] In addition, the fluorine-based water repellent having a perfluoroalkyl group may be a fluorine-based water repellent obtained by modifying a resin with a perfluoroalkyl group. From the viewpoint of improving dispersibility in the resin sheet and stability over time, the resin may be the same type of resin as that which can constitute the resin sheet of the holding pad, such as a polyurethane resin, and the modification method may be, for example, a method of introducing a perfluoroalkyl group into the end and / or side chain of the resin, and the perfluoroalkyl group can be introduced into the resin by using the fluorine telomer listed in the above formula (1). The fluorine-based water repellent having a perfluoroalkyl group may be used alone or in combination of two or more.

[0033] In this embodiment, from the viewpoint of long-term use when subjected to polishing using a strong oxidizing agent, among the above-mentioned fluorotelomers, those in which the carbon number of Rf is 6 are preferred, and those in which the carbon number of R is 1 or 2, i.e., perfluorohexylmethyl group (C6F 13CH2-) or perfluorohexylethyl group (C6F 13 C2H4-). In consideration of dispersibility in the resin sheet and stability over time, the fluorine-based water repellent obtained by modifying a resin with a perfluoroalkyl group is preferably a fluorine-based water repellent obtained by introducing a fluorotelomer into the resin, for example, a resin having a group represented by Rf-R- in the above formula (1), and more preferably a polyurethane resin having a group represented by Rf-R- in the above formula (1). Examples of such resins include polyurethane resins described in International Publication No. 2012 / 172936.

[0034] In addition, when a fluorine-based water repellent such as fluorine telomer is used as the water repellent, and the fluorine-based water repellent contains a fluorine-based water repellent having an Rf of 6 carbon atoms, it is preferable that 60 mol% or more and 100 mol% or less of the fluorine-based water repellent contained in the resin sheet is a fluorine-based water repellent having an Rf of 6 carbon atoms. This limits compounds containing many fluorine atoms such as fluorine telomers having an Rf of more than 6 carbon atoms, and compounds containing few fluorine atoms such as fluorine telomers having an Rf of less than 6 carbon atoms. This makes it possible to reduce the content of compounds containing many fluorine atoms and maintain the holding performance of the polished object, while more effectively suppressing penetration into the continuous pores, and also tends to reduce the content of compounds containing few fluorine atoms and more effectively ensure the above-mentioned moderate water repellency.

[0035] The fluorine-based water repellent may be synthesized by a conventional method, or may be commercially available, such as CRISBON ASISTER SD series (manufactured by DIC Corporation, product name), ASAHIGUARD E series (manufactured by AGC SEIMI CHEMICAL Co., Ltd., product name), NK GUARD S series (manufactured by NICCA CHEMICAL Co., Ltd., product name), and UNIDYNE MULTI series (manufactured by DAIKIN INDUSTRIES, LTD., product name).

[0036] The content of the water repellent in the resin sheet is not particularly limited, but is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.02% by mass or more and 1% by mass or less, and even more preferably 0.05% by mass or more and 0.5% by mass or less, relative to the resin sheet (100% by mass). The water repellent contributes to suppression of the penetration of the polishing liquid containing a strong oxidizing agent into the inside of the holding pad. In particular, it can suppress the penetration of the polishing liquid into fine bubbles that may exist inside the resin sheet. From this viewpoint, the content of the water repellent is preferably 0.01% by mass or more relative to the resin sheet (100% by mass). On the other hand, when the content of the water repellent is 5% by mass or less relative to the resin sheet (100% by mass), it is preferable because it tends to spread moisture approximately uniformly on the holding surface of the holding pad and make it easier for the polished object to be adsorbed with water.

[0037] The resin sheet contains a hydrolysis inhibitor in addition to the polyurethane resin. The hydrolysis inhibitor is a substance that, when contained in the resin sheet, has the effect of suppressing hydrolysis of the resin sheet caused by the surrounding environment. By containing the hydrolysis inhibitor, the resin sheet can suppress hydrolysis caused by a strong oxidizing agent. Whether the resin sheet contains the hydrolysis inhibitor can be confirmed by using a known analysis method such as elemental analysis.

[0038] In this embodiment, from the viewpoint of long-term use when subjected to polishing using a strong oxidizing agent, the hydrolysis inhibitor preferably contains at least one selected from the group consisting of carbodiimide compounds, oxazoline compounds, and epoxy compounds, and more preferably contains a carbodiimide compound from the viewpoint of high effect of eliminating the catalytic activity of protons derived from the carboxyl group terminal generated by hydrolysis of ester bonds and urethane bonds. When a carbodiimide compound is contained as a hydrolysis inhibitor, when a strong oxidizing agent penetrates, the carboxyl group generated by hydrolysis reacts with the carbodiimide compound, and the carboxyl group disappears, and the low molecular weight of the polyurethane resin constituting the resin sheet tends to be suppressed.

[0039] The carbodiimide compound is not particularly limited as long as it contains a carbodiimide group in the molecule. A polycarbodiimide compound containing two or more carbodiimide groups in the molecule is preferred, and a carbodiimide compound represented by the following formula (2) is more preferred. (-N=C=NR-) n (2) In formula (2), n is an integer of 1 or more and 50 or less, preferably an integer of 5 or more and 40 or less, and more preferably an integer of 10 or more and 30 or less. R is a structure derived from any one of an aliphatic polyisocyanate, an alicyclic polyisocyanate, and an aromatic polyisocyanate, which may be used alone or in combination of two or more. Specifically, R is 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, hexamethylene diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone. Examples of the polycarbodiimide compounds include polycarbodiimide compounds which are structures derived from diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, methylcyclohexane diisocyanate, tetramethylxylylene diisocyanate, 2,6-diisopropylphenyl isocyanate, 1,3,5-triisopropylbenzene-2,4-diisocyanate, etc., and are produced by subjecting these polyisocyanate compounds to a decarboxylation condensation reaction in the presence of a carbodiimide catalyst. These may be used alone or in combination of two or more.

[0040] In this embodiment, from the viewpoint of preventing the occurrence of foaming due to a side reaction (decarbonation reaction) with water or the like of a coagulation bath that may be used when preparing a resin sheet and achieving more uniform film formation, it is preferable that the carbodiimide compound is a compound that does not contain an isocyanate group at its terminal, and examples thereof include polycarbodiimides in which both terminals of a polycarbodiimide compound of polyisocyanate are blocked with a monoisocyanate, a monoalcohol, a monoamine, or the like.

[0041] In this embodiment, from the viewpoint of preventing the elution of the polycarbodiimide compound, the hydrolysis inhibitor preferably contains a carbodiimide compound having a carbodiimide equivalent of 50 to 1000, more preferably contains a carbodiimide compound having a carbodiimide equivalent of 100 to 800, and even more preferably contains a carbodiimide compound having a carbodiimide equivalent of 150 to 500. When the carbodiimide equivalent is 50 or more, the density of the carbodiimide group in the carbodiimide compound is low, but the molecular weight is large, so that elution tends to be difficult. The carbodiimide equivalent can be calculated by dividing the "molecular weight of the carbodiimide compound" by the "number of carbodiimide groups in one molecule of the carbodiimide compound". The polycarbodiimide compound may be synthesized by a conventional method, or may be commercially available, such as the Carbodilite series (manufactured by Nisshinbo Chemical Co., Ltd., product name), the Carbodista series (manufactured by Teijin Ltd., product name), and the Stavaxol series (manufactured by Rhein Chemie AG, product name).

[0042] The oxazoline compound is not particularly limited as long as it contains an oxazoline group in the molecule. A bisoxazoline compound is preferred, and specific examples thereof include, but are not limited to, 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4,4-dimethyl-2-oxazoline), 2,2'-bis(4-ethyl-2-oxazoline), 2,2'-bis(4,4'-diethyl-2-oxazoline), 2,2'-bis(4-propyl-2-oxazoline), 2,2'-bis(4-butyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis( ...ethyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline 2,2'-bis(4-hexyl-2-oxazoline), 2,2'-bis(4-phenyl-2-oxazoline), 2,2'-bis(4-cyclohexyl-2-oxazoline), 2,2'-bis(4-benzyl-2-oxazoline), 2,2'-p-phenylenebis(2-oxazoline), 2,2'-m-phenylenebis(2-oxazoline), 2,2'-o-phenylenebis(2-oxazoline), 2,2'-p-phenylenebis(4-methyl- 2-oxazoline), 2,2'-p-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-m-phenylenebis(4-methyl-2-oxazoline), 2,2'-m-phenylenebis(4,4-dimethyl-2-oxazoline), 2,2'-ethylenebis(2-oxazoline), 2,2'-tetramethylenebis(2-oxazoline), 2,2'-hexamethylenebis(2-oxazoline), 2,2'-octamethylenebis(2-oxazoline) , 2,2'-decamethylenebis(2-oxazoline), 2,2'-ethylenebis(4-methyl-2-oxazoline), 2,2'-tetramethylenebis(4,4-dimethyl-2-oxazoline), 2,2'-9,9'-diphenoxyethanebis(2-oxazoline), 2,2'-cyclohexylenebis(2-oxazoline) and 2,2'-diphenylenebis(2-oxazoline), and these may be used alone or in combination of two or more.

[0043] The epoxy compound is not particularly limited as long as it contains an epoxy group in the molecule. Preferred examples of the epoxy compound include glycidyl ester compounds and glycidyl ether compounds.

[0044] Specific examples of the glycidyl ester compound include, but are not limited to, benzoic acid glycidyl ester, t-Bu-benzoic acid glycidyl ester, p-toluic acid glycidyl ester, cyclohexane carboxylic acid glycidyl ester, pelargonic acid glycidyl ester, stearic acid glycidyl ester, lauric acid glycidyl ester, palmitic acid glycidyl ester, behenic acid glycidyl ester, versatic acid glycidyl ester, oleic acid glycidyl ester, linoleic acid glycidyl ester, linoleic acid glycidyl ester, behenolic acid glycidyl ester, stearolic acid glycidyl ester, terephthalic acid diglycidyl ester, isophthalic acid glycidyl ester, glycidyl ester of terephthalic acid ... Examples of the diglycidyl ester include diglycidyl ester of carboxylic acid, diglycidyl ester of phthalic acid, diglycidyl ester of naphthalenedicarboxylic acid, diglycidyl ester of methyl terephthalic acid, diglycidyl ester of hexahydrophthalic acid, diglycidyl ester of tetrahydrophthalic acid, diglycidyl ester of cyclohexanedicarboxylic acid, diglycidyl ester of adipic acid, diglycidyl ester of succinic acid, diglycidyl ester of sebacic acid, diglycidyl ester of dodecanedioic acid, diglycidyl ester of octadecanedicarboxylic acid, triglycidyl ester of trimellitic acid, and tetraglycidyl ester of pyromellitic acid. These may be used alone or in combination of two or more.

[0045] Specific examples of the glycidyl ether compound include, but are not limited to, phenyl glycidyl ether, o-phenyl glycidyl ether, 1,4-bis(β,γ-epoxypropoxy)butane, 1,6-bis(β,γ-epoxypropoxy)hexane, 1,4-bis(β,γ-epoxypropoxy)benzene, 1-(β,γ-epoxypropoxy)-2-ethoxyethane, 1-(β,γ-epoxypropoxy)-2-benzyloxyethane, 2,2-bis-[р-(β,γ-epoxypropoxy)phenyl]propane, and bisglycidyl polyethers obtained by reacting bisphenols such as 2,2-bis-(4-hydroxyphenyl)propane and 2,2-bis-(4-hydroxyphenyl)methane with epichlorohydrin, and the like. These may be used alone or in combination of two or more.

[0046] In this embodiment, the content of the hydrolysis inhibitor in the resin sheet is not particularly limited, but is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.05% by mass or more and 7% by mass or less, and even more preferably 0.1% by mass or more and 5% by mass or less, relative to the resin sheet (100% by mass). When the content of the hydrolysis inhibitor is 0.01% by mass or more relative to the resin sheet (100% by mass), the chemical resistance tends to be improved. In addition, when the content of the hydrolysis inhibitor is 10% by mass or less relative to the resin sheet (100% by mass), the elution of the hydrolysis inhibitor tends to be prevented, and the hydrolysis inhibitor tends to be easily dispersed uniformly in the resin sheet, and the change in the physical properties of the resin sheet itself can also be prevented (that is, the polyurethane resin itself can be selected as desired, and the degree of freedom when considering the composition of the polyurethane resin tends to be increased).

[0047] The reason why the holding pad of this embodiment can ensure a sufficiently long product life even when subjected to polishing using a strong oxidizing agent is presumed to be as follows, although this is not intended to be limiting. In this embodiment, the resin sheet may typically have a structure in which bubbles formed in the resin sheet are interconnected in a three-dimensional network. In this case, the polishing liquid can move between the bubbles from the holding surface, and the polishing liquid tends to be held throughout the inside of the holding pad. Here, if the polishing liquid containing a strong oxidizing agent remains inside the holding pad, the polyurethane resin constituting the resin sheet is hydrolyzed to a low molecular weight, which leads to a significant decrease in physical properties and a tendency to shorten the product life. As a result of intensive research, the present inventors have found that the combined use of a water repellent and a hydrolysis inhibitor contributes to the extension of the product life. For example, when a carbodiimide compound is used as the hydrolysis inhibitor, when a strong oxidizing agent penetrates, the carboxy group generated by hydrolysis reacts with the carbodiimide compound, and the carboxy group disappears, thereby suppressing the further hydrolysis-induced low molecular weight of the polyurethane resin constituting the resin sheet. When only the hydrolysis inhibitor is added, the penetration of the polishing liquid containing a strong oxidizing agent into the interconnecting holes cannot be suppressed, and therefore the hydrolysis of the polyurethane resin sheet cannot be sufficiently suppressed for a long period of time. Therefore, in this embodiment, by using the water repellent together with the hydrolysis inhibitor, the degree of penetration of the polishing liquid containing a strong oxidizing agent can be controlled while suppressing the low molecular weight of the polyurethane resin constituting the resin sheet, and therefore, it is presumed that a sufficiently long product life can be ensured even when polishing using a strong oxidizing agent is performed. Note that, when only the water repellent is added, the penetration of the polishing liquid containing a strong oxidizing agent into the communicating holes can be suppressed, but since the polishing liquid is always present around the holding surface, hydrolysis near the holding surface cannot be avoided. There is a risk that the polyurethane resin sheet will tear due to the polishing load applied to the holding surface. In light of the above, the resin sheet contains both the water repellent and the hydrolysis inhibitor in addition to the polyurethane resin.

[0048] In this embodiment, the resin sheet may contain carbon black, but from the viewpoint of further improving chemical resistance, the carbon black content is preferably low. Specifically, the carbon black content in the resin sheet may be 35% by mass or less, 30% by mass or less, or 25% by mass or less. In this embodiment, from the viewpoint of suppressing deterioration of the resin sheet due to hydrolysis of the carbon black itself by the polishing liquid, the carbon black content in the resin sheet is preferably 10% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass or less (the resin sheet does not substantially contain carbon black). In addition, from the viewpoint of reducing the brittleness of the resin sheet and improving the product life when the carbon black content is low, the carbon black content is preferably 10% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass or less (the resin sheet does not substantially contain carbon black). In addition, when the content of carbon black in the resin sheet is small, the brittleness of the polyurethane resin may be insufficient, and the accuracy of the buffing process may decrease, so it is preferable to adjust the thickness of the resin sheet by film formation conditions, etc., without buffing. In other words, the resin sheet has Layer A, Layer B, and Layer C, and the content of carbon black in the resin sheet is preferably 10% by mass or less, more preferably 1% by mass or less, and even more preferably 0% by mass or less (the resin sheet does not substantially contain carbon black). In such an embodiment, the chemical resistance tends to be significantly improved while maintaining the thickness accuracy of the holding pad.

[0049] In addition to the above-mentioned components, the resin sheet may contain materials that are typically used in resin sheets for holding pads. Furthermore, the resin sheet may contain some residual materials, such as solvents, used in the manufacturing process of the resin sheet.

[0050] (Frame material) The holding pad of this embodiment may be provided with a frame member disposed on the periphery of the holding surface and surrounding the workpiece. The frame member is provided on a surface surrounding the holding surface of the holding pad and prevents the workpiece from slipping sideways during polishing and falling off the holding surface of the holding pad (limiting the range of lateral slippage).

[0051] The shape of the support pad in this embodiment is not particularly limited, and may be various shapes such as a circular shape or a rectangular shape.

[0052] The substrate 114 provided in the holding pad 110 is a member that can be used to support a resin sheet, and is not particularly limited, and may be a substrate included in a conventional holding pad. Specific examples of the substrate include resin films such as polyethylene terephthalate (hereinafter referred to as "PET") film, nonwoven fabrics fixed with polyurethane resin, and foam sheets such as polyurethane resin foam and polyethylene foam.

[0053] The adhesive layer 116 may contain an adhesive or a pressure sensitive adhesive that is used in conventionally known holding pads. Examples of materials for the adhesive layer 116 include various thermoplastic adhesives such as acrylic, nitrile, nitrile rubber, polyamide, polyurethane, and polyester.

[0054] The base material 114 and adhesive layer 116 in the holding pad 110 may be derived from a double-sided tape that includes them. The double-sided tape has adhesive layers containing an adhesive or pressure-sensitive adhesive on both sides of the base material 114, one of the adhesive layers corresponding to the adhesive layer 116. The other adhesive layer is for attaching the holding pad 110 to a holding platen. The double-sided tape may be one included in a conventional holding pad, and may have a release paper (not shown) on the side opposite the base material 114.

[0055] [Method of manufacturing the holding pad] Next, an example of a method for manufacturing the holding pad of this embodiment will be described. Here, a case where the resin sheet 112 is manufactured by a wet film forming method will be described, but the manufacturing method of the resin sheet 112 is not limited to this. For example, the holding pad of this embodiment may be formed by a known molding method. The molding method is not limited to the following, but may be, for example, a method of obtaining a resin sheet by reacting a polyisocyanate compound, a polyol compound, and a polyamine compound.

[0056] An example of a wet film formation method that can be used in this embodiment is a manufacturing method including a step of preparing a resin sheet 112 and a step of bonding a substrate 114 to the resin sheet 112 to obtain the holding pad 110.

[0057] The process of preparing the resin sheet 112 further includes a process of preparing a resin solution containing a resin, a solvent, a water repellent, and a hydrolysis inhibitor (resin solution preparation process), a process of applying the resin solution to the surface of the film-formation substrate (application process), a process of solidifying and regenerating the resin in the resin solution to form a precursor sheet (solidification and regeneration process), a process of removing the solvent from the precursor sheet to obtain the resin sheet 112 (solvent removal process), and a process of grinding and / or partially removing the resin sheet 112 by buffing or slicing, if necessary (grinding and removal process). Each process will be described below.

[0058] First, in the resin solution preparation process, a resin such as the polyurethane resin described above, a solvent capable of dissolving the resin and miscible with the coagulation liquid described below, a water repellent, a hydrolysis inhibitor, and other materials as necessary (e.g., additives such as carbon black, other pigments, hydrophilic activators, and hydrophobic activators) to be contained in the resin sheet 112 are mixed, and the mixture is degassed under reduced pressure as necessary to prepare a resin solution. The solvent is not particularly limited, but examples thereof include N,N-dimethylformamide (hereinafter referred to as "DMF") and N,N-dimethylacetamide. The content of the resin relative to the total amount of the resin solution is not particularly limited, but may be, for example, in the range of 10% by mass to 50% by mass, or in the range of 15% by mass to 35% by mass. The water repellent may be any of those listed in the section on [Holding Pad]. The amount of the water repellent is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 1 part by mass, and even more preferably 0.05 to 0.5 parts by mass, relative to the polyurethane resin (100 parts by mass) in the resin solution. As the hydrolysis inhibitor, the hydrolysis inhibitors listed in the section on [Holding Pad] can be used. The amount of the hydrolysis inhibitor is preferably 0.01 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, relative to the polyurethane resin (100 parts by mass) in the resin solution. As another material, carbon black, which is mentioned in the [Holding Pad] section, can also be used. From the viewpoint of chemical resistance, the amount of carbon black used is preferably 10 mass % or less relative to the polyurethane resin (100 mass parts) in the resin solution, more preferably 1 mass % or less, and even more preferably 0 mass % or less (the resin sheet contains substantially no carbon black). From the viewpoint of adjusting the density, Shore A hardness, etc. of the resulting resin sheet, water and a film-forming assistant such as a pore-forming agent represented by a cellulose derivative may be added to the resin solution.

[0059] Next, in the coating step, the resin solution is applied to the surface of the belt-shaped film-forming substrate, preferably at room temperature, using a coating device such as a knife coater to form a coating film. The thickness of the resin solution applied at this time may be appropriately adjusted so that the final resin sheet 112 has a desired thickness. Examples of materials for the film-forming substrate include resin films such as PET films, fabrics, and nonwoven fabrics. Among these, resin films such as PET films that are difficult for liquid to penetrate are preferred.

[0060] Next, in the solidification and regeneration step, the coating film of the resin solution applied to the film-forming substrate is continuously guided into a solidification liquid mainly composed of a poor solvent for the resin (for example, water in the case of polyurethane resin). In order to adjust the regeneration speed of the resin, an organic solvent such as a polar solvent other than the solvent in the resin solution may be added to the solidification liquid. The temperature of the solidification liquid is not particularly limited as long as it is a temperature at which the resin can be solidified, and may be, for example, 15°C or higher and 65°C or lower. In the solidification liquid, a film (skin layer) is first formed at the interface between the coating film of the resin solution and the solidification liquid, and countless dense micropores are formed in the resin immediately adjacent to the film. Thereafter, due to the cooperative phenomenon of the diffusion of the solvent contained in the resin solution into the solidification liquid and the infiltration of the poor solvent into the resin, the regeneration of the resin having a three-dimensional network structure proceeds. At this time, if the substrate is one that is difficult for liquid to penetrate (e.g., a PET film), the solidification liquid does not penetrate the substrate, so that the solvent in the resin solution is replaced by the poor solvent preferentially near the skin layer, and larger voids (teardrop-shaped bubbles) tend to form in the region inside the skin layer rather than near the skin layer. In this way, a precursor sheet is formed on the substrate.

[0061] Next, in the solvent removal step, the formed precursor sheet is peeled off from the film-forming substrate, and the solvent remaining in the precursor sheet is removed to obtain a resin sheet 112. A conventionally known cleaning solution can be used to remove the solvent. Furthermore, the resin sheet 112 after the solvent has been removed may be dried as necessary. For example, a cylinder dryer equipped with a cylinder having a heat source inside may be used to dry the resin sheet 112, but the drying method is not limited thereto. When a cylinder dryer is used, the precursor sheet is dried by passing it along the circumferential surface of the cylinder. Furthermore, the obtained resin sheet 112 may be wound into a roll.

[0062] Next, in the grinding / removal step, at least one of the main surface skin layer on the holding surface side of the resin sheet 112 (layer A arranged on the holding surface side and containing first pores) and the back surface skin layer on the opposite side (layer B arranged on the joining surface side and containing second pores) is ground and / or partially removed by buffing or slicing. The thickness of the resin sheet 112 can be made uniform by buffing or slicing, so that the pressing force against the object to be polished can be made more uniform, further suppressing damage to the object to be polished and improving the flatness of the object to be polished. In this embodiment, it is preferable not to carry out the grinding / removal step from the viewpoint of further improving chemical resistance.

[0063] Next, the base material 114 is bonded to the resin sheet 112 to obtain the holding pad 110. In this step, for example, a double-sided tape having the base material 114 and an adhesive layer 116 is used to bond the base material 114 to the surface of the resin sheet 112 opposite the polishing surface P via the adhesive layer 116. Furthermore, the other adhesive layer of the double-sided tape and a release paper may be provided on the side of the base material 114 opposite the adhesive layer 116. In this manner, the holding pad 110 is obtained.

[0064] [Method for manufacturing polished product] Next, a polishing method using the holding pad 110 of this embodiment will be described. The method for producing a polished product of this embodiment includes a polishing step in which a polished object held on the holding surface of the holding pad of this embodiment is polished in the presence of a polishing liquid containing a strong oxidizing agent to obtain a polished product. The object to be polished in the polishing process is not particularly limited, but may be, for example, a semiconductor wafer, a semiconductor device, a glass substrate, a substrate for various recording disks, or a glass substrate for a liquid crystal display. Among these, the object to be polished is preferably a semiconductor wafer, and the material of the semiconductor wafer is preferably a compound semiconductor composed of two or more elements. In addition, the holding pad of this embodiment can be suitably used as a holding pad for polishing a compound semiconductor wafer using a polishing liquid containing a strong oxidizing agent.

[0065] An example of polishing will be described. First, a holding pad is attached to the workpiece holder of the polishing machine, and the workpiece is held by the holding pad. To attach the holding pad to the workpiece holder, remove the release paper of the double-sided tape as necessary, and use the exposed adhesive layer to adhere and fix the holding pad to the workpiece holder so that the holding surface faces downward (or upward). Alternatively, if the holding pad does not have double-sided tape, the holding pad is adhered and fixed to the workpiece holder with a separately prepared adhesive or pressure sensitive adhesive. Next, an appropriate amount of water is applied to the holding surface, and the workpiece is pressed against the holding surface, so that the workpiece is held by the holding pad through the surface tension of the water. At this time, the surface to be polished (the surface to be processed) of the workpiece faces downward (or upward). On the other hand, a polishing pad is attached to the surface of a polishing platen arranged below (or above) the workpiece holder so as to face the workpiece holder, so that the polishing surface faces upward (or downward).

[0066] Next, the workpiece holder is moved toward the polishing platen so that the surface of the workpiece contacts the polishing surface of the polishing pad, and the workpiece is transported. Then, a polishing liquid containing chemical components such as abrasive grains (polishing particles; for example, SiO2, CeO2, Al2O3) and a strong oxidizing agent such as potassium permanganate is circulated and supplied between the workpiece and the polishing pad. At the same time, the workpiece holder and the polishing platen are rotated while the workpiece holder presses the workpiece against the polishing pad, and the processed surface of the workpiece is polished by the polishing pad using CMP.

[0067] Although the present embodiment has been described in detail above, the present invention is not limited to this embodiment. For example, in the above-described present embodiment, the adhesive layer 116 is used to bond the resin sheet 112 and the base material 114, but the bonding between them is not limited to using the adhesive layer 116. Furthermore, the holding pad of this embodiment does not need to include a base material, but it is preferable that the holding pad includes a base material from the viewpoint of handling the holding pad. EXAMPLES

[0068] The present embodiment will be described in more detail below with reference to examples, but the present embodiment is not limited to these examples.

[0069] Example 1 A polyurethane resin solution of Example 1 was obtained by mixing 100 parts by mass of a polyester polyurethane resin solution having a 100% modulus of 15 MPa (30 parts by mass as polyester polyurethane resin), 50 parts by mass of DMF, 8 parts by mass of water, 0.06 parts by mass of a fluorine-modified polyurethane resin (water repellent) having perfluorohexylethyl groups at the ends, 1 part by mass of a carbodiimide compound (carbodiimide equivalent: 200) having isocyanate groups blocked at both ends, and 15 parts by mass of a carbon black dispersion (2.8 parts by mass as carbon black). Next, a PET film was prepared as a film-forming substrate, and the polyurethane resin solution was applied thereto using a knife coater, immersed in a coagulation bath (coagulation liquid is water), and the polyurethane resin solution was coagulated and regenerated to form a precursor sheet on the film-forming substrate, and then the film-forming substrate was peeled off, washed, and dried to obtain a resin sheet. Then, without performing surface treatment such as buffing, a PET film was attached to one side (bonding surface) of the resin sheet. Next, a double-sided tape was attached to the surface of the PET film opposite to the surface attached to the resin sheet, to obtain a holding pad of Example 1 having a holding surface. When the cross section of the resin sheet of this holding pad was observed, it was found that the resin sheet had, in this order, Layer A arranged on the holding surface side, Layer C containing teardrop-shaped bubbles, and Layer B arranged on the joining surface side. Here, both Layer A and Layer B contained pores smaller than the teardrop-shaped bubbles in Layer C. The teardrop-shaped bubbles in Layer C and the pores in Layer A and Layer B were bubbles that were connected in a three-dimensional network shape, and it was evaluated that these were obtained by a wet film-forming method.

[0070] Comparative Example 1 A polyurethane resin solution of Comparative Example 1 was obtained by mixing 100 parts by mass of a polyester-based polyurethane resin solution having a 100% modulus of 15 MPa (30 parts by mass as polyester-based polyurethane resin), 50 parts by mass of DMF, 8 parts by mass of water, 1 part by mass of a carbodiimide compound (carbodiimide equivalent: 200) having isocyanate groups blocked at both ends, and 15 parts by mass of a carbon black dispersion (2.8 parts by mass as carbon black). A holding pad of Comparative Example 1 was obtained in the same manner as in Example 1, except that the polyurethane resin solution of Example 1 was changed to the polyurethane resin solution of Comparative Example 1.

[0071] Comparative Example 2 A polyurethane resin solution of Comparative Example 2 was obtained by mixing 100 parts by mass of a polyester-based polyurethane resin solution having a 100% modulus of 15 MPa (30 parts by mass as polyester-based polyurethane resin), 50 parts by mass of DMF, 8 parts by mass of water, 0.06 parts by mass of a fluorine-modified polyurethane resin (water repellent) having a perfluorohexylethyl group at the end, and 15 parts by mass of a carbon black dispersion (2.8 parts by mass as carbon black). A holding pad of Comparative Example 2 was obtained in the same manner as in Example 1, except that the polyurethane resin solution of Example 1 was changed to the polyurethane resin solution of Comparative Example 2.

[0072] Comparative Example 3 A polyurethane resin solution of Comparative Example 3 was obtained by mixing 100 parts by mass of a polyester-based polyurethane resin solution having a 100% modulus of 8.3 MPa (30 parts by mass as polyester-based polyurethane resin), 50 parts by mass of DMF, 3 parts by mass of water, 0.5 parts by mass of a hydrophilic additive, 0.6 parts by mass of a hydrophobic surfactant, and 44 parts by mass of a carbon black dispersion (8.1 parts by mass as carbon black). A holding pad of Comparative Example 3 was obtained in the same manner as in Example 1, except that the polyurethane resin solution of Example 1 was changed to the polyurethane resin solution of Comparative Example 3.

[0073] (Chemical resistance rating 1) Using a universal tensile tester (Tensilon RTC-1210A, manufactured by A&D Co., Ltd.), the tensile strength (a) [kg / mm 2 Next, the resin sheet was immersed in a test polishing liquid prepared by adjusting the pH of the potassium permanganate-based polishing liquid (DSC-201, manufactured by Fujimi Incorporated) to 3.0 with an aqueous nitric acid solution for 24 hours at 25°C. After 24 hours had elapsed from the start of the immersion, the resin sheet was removed from the test polishing liquid, washed with running water, and dried, and the tensile strength (b) [kg / mm 2 From the thus measured tensile strength (a) and tensile strength (b) values, the tensile strength retention rate was calculated using the following formula. The results are shown in Table 1. Tensile strength retention rate [%] = tensile strength (b) / tensile strength (a) × 100

[0074] (Thickness) The thickness of the resin sheet was measured in accordance with the measurement method described in JIS K 6505. That is, the resin sheet was subjected to an initial load of 1 cm in the thickness direction. 2 The thickness was measured when a load of 100 g was applied (stressed).

[0075] (density) The density was calculated from the volume and weight of a sample cut out from the resin sheet.

[0076] (Compressibility and Compressive Elasticity) The compressibility and compressive modulus of the resin sheet were determined using a Shopper-type thickness gauge (pressure surface: circular with a diameter of 1 cm) in accordance with JIS L 1021. That is, at room temperature, the thickness t0 was measured after applying an initial load for 30 seconds from an unloaded state, and then the final load was applied from the thickness t0 state, and the thickness t1 was measured after leaving it as it is for 1 minute. Furthermore, all loads were removed from the thickness t1 state, and after leaving it for 1 minute, the initial load was again applied for 30 seconds, and the thickness t0' was measured. From these, the compressibility and compressive modulus were calculated using the following formula: Compression ratio (%) = (t0-t1) / t0 x 100 Compressive elastic modulus (%) = (t0'-t1) / (t0-t1) x 100 Here, the initial load was 100g / cm 2 , final load is 1120g / cm 2 It was decided.

[0077] (Shore A hardness) The Shore A hardness was measured at 25° C. in accordance with JIS K 7311. That is, a plurality of samples cut out from a resin sheet were stacked to a total thickness of 4.5 mm or more, and the Shore A durometer was used to measure the hardness.

[0078] [Table 1]

[0079] The addition of a water repellent and a carbodiimide compound improved the tensile strength retention rate. It was also confirmed that a sufficiently high tensile strength retention rate could not be obtained with either one alone. It is presumed that this is due to the combined use of two types of additives, which are thought to have different mechanisms of action. A high tensile strength retention rate indicates that deterioration caused by the polishing liquid is suppressed, and as a result, an improvement in the product lifespan is expected.

[0080] Next, in order to confirm the effect of the carbon black content in the resin sheet, the following study was carried out.

[0081] Example 2 A polyurethane resin solution of Example 2 was obtained by mixing 100 parts by mass of a polyester-based polyurethane resin solution having a 100% modulus of 15 MPa (30 parts by mass as polyester-based polyurethane resin), 50 parts by mass of DMF, 6 parts by mass of water, 0.12 parts by mass of a fluorine-modified polyurethane resin (water repellent) having perfluorohexylethyl groups at the ends, and 1 part by mass of a carbodiimide compound (carbodiimide equivalent: 200) having isocyanate groups blocked at both ends. A supporting pad of Example 2 was obtained in the same manner as in Example 1, except that the polyurethane resin solution of Example 1 was changed to the polyurethane resin solution of Example 2. When the cross section of the resin sheet of this holding pad was observed, it was found that the resin sheet had, in this order, Layer A arranged on the holding surface side, Layer C containing teardrop-shaped bubbles, and Layer B arranged on the joining surface side. Here, both Layer A and Layer B contained pores smaller than the teardrop-shaped bubbles in Layer C. The teardrop-shaped bubbles in Layer C and the pores in Layer A and Layer B were bubbles that were connected in a three-dimensional network shape, and it was evaluated that these were obtained by a wet film-forming method.

[0082] (Chemical resistance rating 2) The tensile strength (a) [kg / mm ​​2 ] of the resin sheets of Examples 1 and 2 before immersion in the test polishing liquid was measured in accordance with JIS K 6550 using a universal tensile tester (Tensilon RTC-1210A, manufactured by A&D Co., Ltd.).2 Next, the resin sheet was immersed in a test polishing liquid prepared by adjusting the pH of the potassium permanganate-based polishing liquid (DSC-201, manufactured by Fujimi Incorporated) to 2.0 with an aqueous nitric acid solution at 25°C for 24 hours. After 24 hours had elapsed since the start of the immersion, the resin sheet was removed from the test polishing liquid, washed with running water, and dried, and the tensile strength (b) [kg / mm 2 From the values ​​of tensile strength (a) and tensile strength (b) thus measured, the tensile strength retention rate was calculated according to the following formula. Tensile strength retention rate [%] = tensile strength (b) / tensile strength (a) × 100

[0083] (Chemical resistance rating 3) The tensile strength (a) [kg / mm ​​2 ] of the resin sheets of Example 2 and Comparative Example 3 before immersion in the test polishing liquid was measured in accordance with JIS K 6550 using a universal tensile tester (Tensilon RTC-1210A, manufactured by A&D Co., Ltd.). 2 Next, the resin sheet was immersed in a test polishing liquid prepared by adjusting the pH of the potassium permanganate-based polishing liquid (DSC-201, manufactured by Fujimi Incorporated) to 2.0 with an aqueous nitric acid solution for 48 hours at 25°C. After 48 hours had elapsed since the start of the immersion, the resin sheet was removed from the test polishing liquid, washed with running water, and dried, and the tensile strength (b) [kg / mm 2 From the values ​​of tensile strength (a) and tensile strength (b) thus measured, the tensile strength retention rate was calculated according to the following formula. Tensile strength retention rate [%] = tensile strength (b) / tensile strength (a) × 100

[0084] From the results of Chemical Resistance Evaluations 2 and 3, the chemical resistance was evaluated according to the following criteria. ◎: Tensile strength retention rate 90% or more ○: Tensile strength retention rate is 50% or more and less than 90% △: Tensile strength retention rate less than 50% ×: The appearance was so damaged that the tensile strength retention rate could not be measured.

[0085] [Table 2]

[0086] In Example 2, the result of chemical resistance evaluation 2 was a tensile strength retention of 94.5%, and the result of chemical resistance evaluation 3 was a tensile strength retention of 93.5%, demonstrating an extremely significant improvement in chemical resistance. Thus, by reducing the carbon black content, a tendency was observed for the tensile strength retention to be further improved. A high tensile strength retention calculated in the chemical resistance evaluation under harsher conditions indicates that deterioration caused by the polishing liquid is suppressed for a longer period of time, and as a result, a further improvement in product life is expected.

Claims

1. A holding pad including a resin sheet having a holding surface for holding an object to be polished and a bonding surface different from the holding surface, The resin sheet comprises a polyurethane resin, a water repellent, and a hydrolysis inhibitor.

2. The holding pad according to claim 1 , wherein the content of carbon black in the resin sheet is 10% by mass or less.

3. 2. The holding pad according to claim 1, wherein the water repellent comprises at least one selected from the group consisting of a fluorine-based water repellent, a silicone-based water repellent, and a hydrocarbon-based water repellent.

4. The support pad of claim 1 , wherein the water repellent agent comprises a polyurethane resin having a perfluoroalkyl group.

5. 2. The supporting pad according to claim 1, wherein the hydrolysis inhibitor comprises at least one selected from the group consisting of carbodiimide compounds, oxazoline compounds, and epoxy compounds.

6. 2. The support pad of claim 1, wherein the hydrolysis inhibitor comprises a carbodiimide compound having a carbodiimide equivalent weight of 50 or more and 1000 or less.

7. The support pad according to claim 1 , wherein the resin sheet contains air bubbles that are interconnected in a three-dimensional network.

8. The supporting pad according to claim 7 , wherein the resin sheet is formed by a wet film forming method.

9. The resin sheet is A layer A is disposed on the support surface side and includes first pores; A layer B is disposed on the joining surface side and includes second pores; a layer C disposed between the layer A and the layer B and including teardrop-shaped bubbles larger than the first pores and the second pores; The support pad of claim 8 having

10. The holding pad according to claim 9 , wherein the content of carbon black in the resin sheet is 10% by mass or less.

11. The density of the resin sheet is 0.15 g / cm 3 0.35g / cm or more 3 is as follows: The holding pad according to claim 1 , wherein the resin sheet has a Shore A hardness of 15 degrees or more and 50 degrees or less.

12. preparing a resin solution containing a polyurethane resin, a solvent, a water repellent, and a hydrolysis inhibitor; applying the resin solution to a surface of a film-forming substrate; A step of coagulating and regenerating the resin in the resin solution to form a precursor sheet; obtaining a resin sheet from the precursor sheet; Including, The method for producing a holding pad, wherein the resin sheet contains the polyurethane resin, the water repellent, and the hydrolysis inhibitor.

13. A method for producing a polished product, comprising a polishing step of polishing a workpiece held on the holding surface of the holding pad according to any one of claims 1 to 11 in the presence of a polishing liquid containing a strong oxidizing agent to obtain a polished product.

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