Polishing cloth

Abstract

To provide means for prolonging lifetime of a polishing cloth.SOLUTION: A polishing cloth for use in chemical mechanical polishing comprises a base material part that is made of a nonwoven fabric, and a resin part that is made of a resin composition with which the nonwoven fabric is impregnated. The resin composition contains a resin, and a resin part protectant for inhibiting the oxidation of the resin.SELECTED DRAWING: Figure 3a

Description

[Technical Field]

[0001] The present invention relates to a polishing cloth. [Background technology]

[0002] Conventionally, semiconductor wafers and the like have been polished by a method known as chemical mechanical polishing (CMP). Chemical mechanical polishing uses a slurry containing components such as abrasive grains for mechanically polishing the object to be polished and chemical components for chemically promoting the polishing. Furthermore, polishing cloths are used to polish objects such as wafers (see, for example, Patent Document 1). Known polishing cloths include a nonwoven fabric serving as the base material of the polishing cloth and a resin composition impregnated into the nonwoven fabric. This type of polishing cloth is also widely used in chemical mechanical polishing of objects other than wafers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-107106 Summary of the Invention [Problem to be solved by the invention]

[0004] In chemical mechanical polishing using an abrasive cloth, the polishing rate decreases and scratches occur on the surface of the workpiece as the workpiece is polished repeatedly, so the abrasive cloth is replaced with a new one after a certain period of use. From the viewpoint of work efficiency in polishing work, it is desired that the abrasive cloth have a longer service life. Although various methods for extending the service life of abrasive cloths have been studied, there is still room for improvement. Therefore, an object of the present invention is to provide a means for extending the service life of abrasive cloths. [Means for solving the problem]

[0005] The present invention provides A polishing cloth used in chemical mechanical polishing, The device comprises a substrate part made of a nonwoven fabric and a resin part made of a resin composition impregnated into the nonwoven fabric, The resin composition includes: Resin and and a resin part protecting agent that inhibits oxidation of the resin. [Effects of the Invention]

[0006] In such a polishing cloth, oxidation of the resin due to chemical components contained in the slurry used in chemical mechanical polishing is suppressed, and therefore the service life of the polishing cloth can be extended. [Brief explanation of the drawings]

[0007] [Figure 1a] FIG. 1a is a schematic plan view of a polishing cloth according to one embodiment. [Figure 1b] FIG. 1b is a schematic side view of a polishing cloth according to one embodiment. [Figure 1c] FIG. 1c is a schematic cross-sectional view (cross-sectional photograph) of a polishing cloth according to one embodiment. [Figure 2a] FIG. 2a is a schematic plan view of a polishing cloth according to another embodiment. [Figure 2b] FIG. 2b is a schematic plan view of a polishing cloth according to another embodiment. [Figure 2c] FIG. 2c is a schematic plan view of a polishing pad according to another embodiment. [Figure 3a] FIG. 3a is a cross-sectional photograph of the polishing cloth of the example. [Figure 3b] FIG. 3b is a cross-sectional photograph of the polishing cloth of the comparative example. [Figure 4] FIG. 4 is an IR chart comparing the resin part protecting agent used in producing the polishing cloth of the example with the surface deposits of the produced polishing cloth. DETAILED DESCRIPTION OF THE INVENTION

[0008] The polishing cloth of this embodiment is a sheet having a predetermined thickness as shown in FIGS. 1a to 1c. The polishing cloth 1 of this embodiment is suitable for use in chemical mechanical polishing using a slurry containing abrasive grains and chemical components. The use of the polishing cloth 1 is not particularly limited, but it can be used, for example, in chemical mechanical polishing of semiconductor wafers as the object to be polished. Examples of semiconductor wafers to be polished include silicon (Si) wafers, silicon carbide (SiC) wafers, gallium oxide (Ga2O3) wafers, gallium nitride (GaN) wafers, and aluminum nitride (AlN) wafers.

[0009] At least one surface of the polishing cloth 1 is a polishing surface 1s for polishing an object to be polished. The outline shape of the polishing cloth 1 of this embodiment is circular when viewed from above. The polishing cloth 1 of this embodiment has a radial direction D1 parallel to the polishing surface 1s and a thickness direction D2 perpendicular to the polishing surface 1s. The polishing cloth 1 further has a circumferential direction D3 that is a direction that rotates around an imaginary axis that passes through the center and extends in the thickness direction D2.

[0010] The polishing cloth 1 of this embodiment may have recesses 1r recessed from the polishing surface 1s, as shown in Figures 2a to 2c. When the polishing cloth 1 has recesses 1r, a plurality of recesses 1r may be scattered on at least one side of the polishing cloth 1 (the side having the polishing surface 1s), as shown in Figure 2a. The recesses 1r may extend in the circumferential direction D3 to form annular grooves, as shown in Figure 2b. The polishing cloth 1 may have a plurality of annular grooves of different diameters arranged concentrically at predetermined intervals in the radial direction D1. The polishing cloth 1 may have recesses 1r arranged in a grid pattern, as shown in Figure 2c.

[0011] As will be described later, the polishing cloth 1 of this embodiment has a longer service life by suppressing oxidation of the resin due to chemical components contained in the slurry. Compared to the polishing cloth 1 shown in Figure 1a, which has a flat polishing surface 1s side and no recesses 1r formed, the polishing cloth 1 with recesses 1r has a large surface area and is more susceptible to resin oxidation, which can be seen as a significant advantage.

[0012] The polishing cloth 1 of this embodiment comprises a base material portion 11 made of nonwoven fabric and a resin portion 12 made of a resin composition impregnated into the nonwoven fabric, the resin composition containing a resin and a resin portion protective agent that forms an organic deposit on the surface of the resin portion 12 and suppresses oxidation of the resin.

[0013] The polishing cloth 1 of this embodiment may have a thickness of, for example, 0.8 mm or more and 3.0 mm or less. The thickness of the polishing cloth 1 can be measured using a digital micrometer and can be calculated as the arithmetic average of thicknesses measured at multiple randomly selected locations (e.g., 10 locations). The thickness of the substrate 11 in this embodiment is the same as that of the polishing cloth 1. The resin portion 12 is provided so as to cover the entire substrate 11 and has the same thickness as the substrate 11. The resin portion 12 may be configured to fill all of the voids within the nonwoven fabric constituting the substrate 11 with the resin composition, or may be configured so that the resin composition occupies only part of the voids without filling all of the voids within the nonwoven fabric with the resin composition. That is, the polishing cloth 1 may have the substrate 11, the resin portion 12, and the void portion 13, or may be configured only with the substrate 11 and the resin portion 12 without the void portion 13 provided therein.

[0014] The presence of the voids 13 allows the polishing cloth 1 to exhibit excellent cushioning properties. The polishing cloth 1 having the voids 13 can be in good contact with the workpiece during polishing. The polishing cloth 1 has an apparent density of, for example, 600 kg / m 3 The apparent density of the polishing cloth 1 is 500 kg / m or less. 3 The apparent density of the polishing cloth 1 may be, for example, 300 kg / m or less. 3 The apparent density of the polishing cloth 1 is 350 kg / m or more. 3 The apparent density can be measured in accordance with JIS K7222:2005.

[0015] The mass per unit area (basis weight) of the nonwoven fabric constituting the base material 11 of the polishing cloth 1 is, for example, 200 g / m 2 More than 600g / m 2The nonwoven fabric may be, for example, a spunlace nonwoven fabric or a needle-punched nonwoven fabric, or may be a thermally bonded nonwoven fabric or a chemically bonded nonwoven fabric. As the nonwoven fabric, for example, a nonwoven fabric containing polyester fibers or polyamide fibers can be used. The average fineness of the nonwoven fabric may be, for example, 10 dtex or less. The average fineness of the nonwoven fabric may be, for example, 8 dtex or less, or may be 5 dtex or less. The average fineness of the nonwoven fabric is, for example, 0.1 dtex or more.

[0016] The resin composition constituting the resin portion 12 of the polishing cloth 1 may contain, for example, polyurethane resin, polyamide resin, polyvinyl alcohol resin, etc. From the viewpoint of impregnation into the nonwoven fabric and adhesion to the fibers constituting the nonwoven fabric, the base resin of the resin composition is preferably a thermosetting polyurethane resin. The resin composition may contain two or more types of resin. Of all the resins contained in the resin composition, the proportion of polyurethane resin may be 80 mass % or more, 90 mass % or more, 95 mass % or more, or 98 mass % or more. The resin contained in the resin composition may essentially be polyurethane resin only.

[0017] The polyurethane resin may be a polyether-based polyurethane resin or a polyester-based polyurethane resin. In terms of excellent hydrolysis resistance, the polyurethane resin is preferably a polyether-based polyurethane resin, and more preferably a polyether-based polyurethane resin containing polytetramethylene glycol (PTMG) as a main structural unit. The polyether-based polyurethane resin may be a polymer containing a polyether-based polyol and a polyisocyanate compound as structural units, with these being bonded via urethane bonds, or may further be a polymer containing a polyamine compound as a structural unit and containing a urea bond. In terms of excellent chemical resistance, the polyurethane resin preferably contains a urea bond. Examples of compounds preferred as structural units of polyurethane resins for introducing urea bonds include 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA).

[0018] The resin composition of this embodiment contains a resin part protective agent to prevent the above-mentioned resin from being oxidized. In the polishing pad 1 of this embodiment, organic deposits containing the resin part protective agent are adhered to the surface of the resin part 12. The resin part protective agent is preferably one that can form such organic deposits on the surface of the resin part 12.

[0019] In this embodiment, the organic deposits are formed by a portion of the resin part protective agent contained in the resin part 12 bleeding out as a precipitate from the resin part 12 and adhering to the surface of the resin part 12. If the amount of the resin part protective agent that bleeds out from the resin part 12 is deemed insufficient to suppress oxidation, the resin part protective agent may be separately applied by a method such as spray coating to adhere to the surface of the resin part 12.

[0020] When a resin part protective agent is applied to the polishing pad 1 separately from bleeding out the resin part 12 to form an organic deposit on the surface of the resin part 12, the resin part protective agent contained in the resin part 12 and the resin part protective agent applied separately may be the same or different. The organic deposit that adheres to the surface of the resin part 12 due to bleed-out may contain compounds derived from the resin part protective agent in addition to the resin part protective agent. Examples of compounds derived from the resin part protective agent include decomposition products of the resin part protective agent, polymers formed by bonding resin part protective agents together, and reaction products of the resin part protective agent with another compound.

[0021] The resin part protective agent of this embodiment effectively inhibits oxidation of the resin by forming organic deposits on the surface of the resin part 12. Antioxidants are effective as a component for inhibiting oxidation. While some general resin products contain antioxidants as components for inhibiting oxidation, antioxidants are typically used to prevent bleed-out onto the surface of the resin product. This is because their primary purpose is to inhibit chain reactions caused by radicals generated inside the resin product and oxygen entering the resin product from the air. Therefore, antioxidants must be uniformly dispersed throughout the resin product and are generally not used in a manner that would cause deposits to form on the surface. On the other hand, the resin part protective agent of this embodiment aims to protect the resin part from the chemical components of the slurry, and therefore is used to form deposits on the surface, effectively inhibiting oxidation in the surface layer, rather than targeting oxygen diffusing into the resin part.

[0022] In this embodiment, the resin part protective agent is preferably one that easily migrates from the interior to the surface of the resin part 12. For example, if a resin product contains a component with a relatively small molecular weight (a molecular weight of several hundred) that has low affinity for the resin, it will easily migrate (bleed out) to the surface of the resin product. Affinity with the resin can be determined based on differences in polarity, etc. Examples of components that exhibit such migration include surfactants, various plastic chemicals, oils, etc. When using a surfactant as the resin part protective agent, it is sufficient to select one that easily migrates to the surface of the resin part 12 using an index such as the HLB value. However, because surfactants may be washed away by the slurry, it is considered preferable to use plastic chemicals or the like as the resin part protective agent from the perspective of durability of the effect.

[0023] As the resin part protective agent, a compound having a function of suppressing the autoxidation reaction caused by peroxy radicals is considered to be suitable. From the viewpoint of functionality, for example, a compound having a radical chain inhibition ability or a compound having peroxide decomposition ability is considered to be suitable as the resin part protective agent. Specifically, for example, a phenol-based antioxidant, a phosphorus-phenol-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant, etc. are considered to be preferable as the resin part protective agent.

[0024] Examples of phenolic antioxidants include 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, and pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] ("ADK STAB"). AO-60 (trade name, manufactured by ADEKA Corporation), octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate ("Irganox 1076" (trade name, manufactured by BASF), "ADEKA STAB AO-50" (trade name, manufactured by ADEKA Corporation)), 3,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione ("ADEKA STAB AO-20 (trade name, manufactured by ADEKA Corporation), 1,3,5-tris((4-tert-butyl-3-hydroxy-2,6-xylyl)methyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, thiodiethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxyC7 -C9 side chain alkyl esters, 4,6-bis(octylthiomethyl)-o-cresol, 2,4-bis(n-octylthio)-6-(4-hydroxy3',5'-di-tert-butylanilino)-1,3,5-triazine, 3,9-bis(2-(3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5,5) Undecane ("ADEKA STAB AO-80" (trade name, manufactured by ADEKA Corporation)), triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 4,4'-thiobis(6-tert-butyl-3-methylphenol), 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-4-hydroxyphenylpropionate, ... Trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, 1,6-hexanediol-bis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 1,3,5-tris(4-hydroxybenzyl)benzene, 4,4',4''-(1-methylpropanyl-3-ylidene)tris(6-tert-butyl-m-cresol) ("ADK STAB AO-30 (trade name, manufactured by ADEKA Corporation), 6,6'-di-tert-butyl-4,4'-butylidenedi-m-cresol ("ADEKA STAB AO-40" (trade name, manufactured by ADEKA Corporation)), "Irganox 3125" (trade name, manufactured by BASF), "Sumilizer BHT" (trade name, manufactured by Sumitomo Chemical Co., Ltd.), "Sumilizer GA-80" (trade name, manufactured by Sumitomo Chemical Co., Ltd.), "Sumilizer GS" (trade name, manufactured by Sumitomo Chemical Co., Ltd.), "Cyanox 1790" (trade name, manufactured by Cytec Co., Ltd.), Vitamin E (manufactured by Eisai Co., Ltd.), etc.

[0025] Examples of phosphorus-phenol-based antioxidants include 2,10-dimethyl-4,8-di-tert-butyl-6-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propoxy]-12H-dibenzo[d,g][1,3,2]dioxaphosphocin, 2,4,8,10-tetra-tert-butyl-6-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosphepine, and 2,4,8,10-tetra-tert-butyl-6-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]-dibenzo[d,f][1,3,2]dioxaphosphepine ("Sumilizer GP" (trade name, manufactured by Sumitomo Chemical Co., Ltd.)).

[0026] Examples of phosphorus-based antioxidants include diphenyl isooctyl phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, diphenyl isodecyl phosphite, diphenyl isodecyl phosphite, triphenyl phosphate, tributyl phosphate, diisodecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, cyclic neopentanetetraylbis(2,4-di-tert-butylphenyl) cyclohexyl) phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl) phosphite, 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butylbenzo[d,f][1,3,2]dioxaphosphepine, tris(nonylphenyl) phosphite ("ADK STAB") 1178" (trade name, manufactured by ADEKA Corporation), tris(mono- and dinonylphenyl mixed) phosphite, diphenyl mono(tridecyl) phosphite, 2,2'-ethylidenebis(4,6-di-tert-butylphenol) fluorophosphite, phenyl diisodecyl phosphite, tris(2-ethylhexyl) phosphite, tris(isodecyl) phosphite, tris(tridecyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tetrakis(2,4-di-tert-butylphenol) Nyl)-4,4'-biphenylene-di-phosphonite, 4,4'-isopropylidenediphenyltetraalkyl(C12-C15)diphosphite, 4,4'-butylidenebis(3-methyl-6-tert-butylphenyl)-ditridecylphosphite, bis(nonylphenyl)pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol-di-phosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl-phosphite), 1,1,3-tris(2-methyl-4-ditridecylphosphite-5-tert-butylphenyl)butane, tetrakis(2,4-di-tert-butyl-5-methylphenyl)-4,4'-biphenylene diphosphonite, tri-2-ethylhexyl phosphite, triisodecyl phosphite, tristearyl phosphite, phenyl diisodecyl phosphite, trilauryl trithiophosphite, distearyl pentaerythritol diphosphite, tris( nonylatedophenyl)phosphite tris[2-[[2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphin-6-yl]oxy]ethyl]amine, bis(2,4-bis(1,1-dimethylethyl)-6-methylphenyl)ethyl ester phosphorous acid, 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, bis(2,4- Di-tert-butylphenyl)pentaerythritol diphosphite, 2,2'-methylenebis(4,6-di-tert-butyl-1-phenyloxy)(2-ethylhexyloxy)phosphorus, triphenyl phosphite, 4,4'-butylidene-bis(3-methyl-6-tert-butylphenylditridecyl)phosphite, octadecyl phosphite, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-te rt-Butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2,2-methylenebis(4,6-di-tert-butylphenyl)octylphosphite, tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4'-diylbisphosphonite, bis[2,4-bis(1,Examples of suitable phosphonic acid include 1-dimethylethyl)-6-methylphenyl]ethyl ester, phosphonic acid, "ADK STAB 329K" (trade name, manufactured by ADEKA Corporation), "ADK STAB PEP36" (trade name, manufactured by ADEKA Corporation), "ADK STAB PEP-8" (trade name, manufactured by ADEKA Corporation), "Sandstab P-EPQ" (trade name, manufactured by Clariant), "WESTON 618" (trade name, manufactured by GE), "WESTON 619G" (trade name, manufactured by GE), and "ULTRANOX 626" (trade name, manufactured by GE).

[0027] Examples of sulfur-based antioxidants include dialkylthiodipropionate compounds such as dilauryl, dimyristyl, and distearyl thiodipropionate ("Sumilizer TPM" (trade name, manufactured by Sumitomo Chemical Co., Ltd.)), β-alkylmercaptopropionic acid ester compounds of polyols such as tetrakis[methylene(3-dodecylthio)propionate]methane and tetrakis[methylene(3-laurylthio)propionate]methane, and 2-mercaptobenzimidazole.

[0028] The resin part protective agent may be an acid scavenger such as a metal soap such as calcium stearate or zinc stearate; a mineral agent such as hydrotalcite or hydrocalumite; or a basic metal oxide such as calcium oxide, zinc oxide, or magnesium oxide; or a light stabilizer having radical scavenging ability.

[0029] The resin part protecting agent is preferably a phenolic antioxidant. The phenolic antioxidant may be, for example, a so-called hindered phenolic antioxidant in which tertiary butyl is bonded to each of the two ortho positions relative to the hydroxyl group. Hindered phenolic antioxidants are suitable in that they have a bulky molecular structure and exhibit an appropriate diffusion rate in the resin.

[0030] In order to be unevenly distributed on the surface layer of the resin portion 12 and form deposits on the surface, it is preferable that the resin portion protective agent not only has poor compatibility with the resin contained in the resin portion 12 but also exhibits moderate diffusibility (solubility). That is, taking into account the migration speed within the resin portion, a substance that exhibits a certain degree of solubility in the resin and can migrate through the resin to the surface layer of the resin portion is suitable as the resin portion protective agent. From this perspective, when the base polymer of the resin portion 12 is a polyurethane resin, it is considered suitable that the resin portion protective agent has an isocyanuric acid skeleton or a triazine ring skeleton. Specifically, phenolic antioxidants in which a hydroxyphenyl group is bonded to an isocyanuric acid skeleton, such as 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione and 1,3,5-tris((4-tert-butyl-3-hydroxy-2,6-xylyl)methyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, are considered to be suitable. In such phenolic antioxidants having an isocyanuric acid skeleton, one or more hydrogen atoms of the hydroxyphenyl may or may not be substituted with tertiary butyl or the like.

[0031] When using such an antioxidant as the resin part protective agent, it is preferable that the total amount of the antioxidant attached to the surface of the resin part 12 and the antioxidant contained inside the resin part 12 is at a certain ratio or more. When the amount of resin contained in the resin composition constituting the resin part 12 is taken as 100 parts by mass, the total amount of the antioxidant attached to the surface of the resin part 12 as organic deposits and the antioxidant contained in the resin part 12 is preferably at a ratio of more than 2 parts by mass. This ratio is more preferably 3 parts by mass or more, and even more preferably 5 parts by mass or more. The total amount of the antioxidants is, for example, 20 parts by mass or less. The total amount of the antioxidants may be 18 parts by mass or less, 16 parts by mass or less, or 14 parts by mass or less.

[0032] The antioxidant is preferably in a solid (powdered) or viscous liquid state at room temperature (for example, 23°C).

[0033] The resin part protective agent to be contained in the resin part 12 can be contained in the resin part 12 by blending it with the raw materials used to form the resin part 12. When the resin part 12 is made of a polyurethane resin composition, the resin part protective agent can be contained in the resin part 12 by adding it to either or both of a polyol and a polyisocyanate and allowing them to react. When the resin part 12 is formed using a prepolymer obtained by reacting a polyol and a polyisocyanate, the resin part protective agent may be contained in the resin part 12 by adding it to either or both of the prepolymer and a curing agent (polyol, polyamine) for the prepolymer. Furthermore, the resin part protective agent may be contained in the resin part 12 by adding it to an impregnation liquid containing a polyurethane resin when the resin part 12 is formed by impregnating a nonwoven fabric with the impregnation liquid.

[0034] To form organic deposits on the surface of the resin portion 12 using the resin portion protective agent contained in the resin portion 12, natural surface migration may be allowed, or the surface migration of the resin portion protective agent may be promoted by using an organic solvent, etc. For example, the polishing pad 1 of this embodiment can be produced through the following two-stage impregnation process.

[0035] Specifically, the polishing cloth 1 of this embodiment can be produced by carrying out a first impregnation step, wet impregnation, in which polyurethane resin is impregnated into a nonwoven fabric, and then carrying out a second impregnation step, dry impregnation, in which polyurethane resin is impregnated into a nonwoven fabric.

[0036] In wet impregnation, a polyurethane resin is dissolved in a water-soluble organic solvent to obtain a first impregnation liquid. Examples of water-soluble organic solvents include dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, and dimethylacetamide. Next, a nonwoven fabric is immersed in the first impregnation liquid, and the nonwoven fabric is then immersed in water. This replaces the water-soluble organic solvent in the first impregnation liquid impregnated into the nonwoven fabric, solidifying the polyurethane resin and adhering to the surface of the fibers that make up the nonwoven fabric. The first impregnation step is carried out so that the first polyurethane resin composition, which is the cured product of the first impregnation liquid, covers the fibers that make up the nonwoven fabric, forming a resin layer on the fiber surface, while leaving voids within the nonwoven fabric.

[0037] In dry impregnation, a prepolymer having an isocyanate group as a terminal group, a curing agent (an organic compound having active hydrogen), and an organic solvent are mixed to obtain a second impregnation liquid. Examples of the organic solvent include methyl ethyl ketone, acetone, alcohol, and ethyl acetate. The wet-impregnated nonwoven fabric is then immersed in the second impregnation liquid, and the nonwoven fabric is heated in a drying oven. This evaporates the organic solvent, and the prepolymer and the curing agent undergo a curing reaction. In this manner, the fibers constituting the nonwoven fabric are coated with two layers of polyurethane resin compositions: the first polyurethane resin composition, which is the cured product of the first impregnation liquid, and the second polyurethane resin composition, which is the cured product of the second impregnation liquid. In this embodiment, the second impregnation step is performed so that voids 13 are ultimately formed within the polishing pad 1 without filling the internal voids left in the first impregnation step with the second polyurethane resin composition.

[0038] In the second impregnation process, the organic solvent evaporates mainly from the surface layers on one side and multiple sides of the polishing cloth 1, and at that time, the resin part protective agent contained in the central part of the thickness direction D2 of the polishing cloth 1 is carried along with the organic solvent and appears on both surfaces of the polishing cloth 1 as organic deposits.

[0039] As described above, the manufacturing method of the polishing cloth 1 in this embodiment is a manufacturing method of a polishing cloth for chemical mechanical polishing having a base portion made of a nonwoven fabric and a resin portion made of a resin composition impregnated into the nonwoven fabric, and includes the steps of preparing an impregnation liquid containing a resin component containing a resin or a resin precursor, a solvent capable of dissolving the resin component, and a resin part protective agent that suppresses oxidation of the resin, impregnating the nonwoven fabric with the impregnation liquid, and removing the solvent from the impregnation liquid that has impregnated the nonwoven fabric. By removing the solvent, the resin part is formed from the resin composition containing the resin and the resin part protective agent, and organic deposits derived from the resin part protective agent are formed on the surface of the resin part.

[0040] In this method of manufacturing a polishing cloth, it is preferable to manufacture the polishing cloth by preparing an impregnation liquid so that the resin part protective agent is present in a proportion of more than 2 parts by mass and not more than 20 parts by mass per 100 parts by mass of the resin component; it is more preferable to manufacture the polishing cloth by preparing an impregnation liquid so that the resin part protective agent is present in a proportion of 3 parts by mass or more and 16 parts by mass or less; and it is even more preferable to manufacture the polishing cloth by preparing an impregnation liquid so that the resin part protective agent is present in a proportion of 5 parts by mass or more and 14 parts by mass or less.

[0041] If the first impregnation liquid contains a large amount of resin part protective agent, the adhesive strength between the fibers constituting the nonwoven fabric and the first polyurethane resin composition may not be fully exerted. Therefore, when manufacturing the polishing cloth 1 in this embodiment, the content of the resin part protective agent in the first impregnation liquid may be kept small, or the first impregnation liquid may not contain any resin part protective agent at all, and the second impregnation liquid may contain more resin part protective agent than the first impregnation liquid.

[0042] That is, in the manufacturing method of the polishing cloth 1 of this embodiment, in addition to preparing a second impregnation liquid containing the resin part protective agent, a first impregnation liquid containing a lower amount of resin part protective agent than the second impregnation liquid may be prepared, the nonwoven fabric may be impregnated with the first impregnation liquid, a first resin composition derived from the first impregnation liquid may be adhered to the fibers constituting the nonwoven fabric, and the nonwoven fabric to which the first resin composition has been adhered may be impregnated with the second impregnation liquid, so that the first resin composition adhered to the fibers is covered with the second resin composition derived from the second impregnation liquid to form the resin part. Note that the phrase "containing a lower amount of resin part protective agent than the second impregnation liquid" in the above also means that the first impregnation liquid may not contain any resin part protective agent at all.

[0043] The polishing pad 1 obtained as described above can suppress oxidation of the resin portion 12 even when chemical mechanical polishing is performed using a slurry containing an oxidizing agent as a chemical component, thereby extending the service life. The polishing cloth 1 is used in chemical mechanical polishing using a slurry containing an oxidizing agent such as hydrogen peroxide, peracetic acid, perbenzoic acid, a permanganate compound such as potassium permanganate, or ammonium persulfate. The polishing cloth 1 of this embodiment is suitable for use in chemical mechanical polishing using a highly oxidizing agent such as potassium permanganate.

[0044] When chemical mechanical polishing of a wafer or the like is performed using a slurry containing a highly oxidizing agent, the resin located near the polishing surface 1s may oxidize and deteriorate, causing it to fall off from the nonwoven fabric constituting the substrate 11 during polishing. This makes it easier for polishing debris and abrasive grains to enter the voids 13 inside the polishing cloth 1, reducing the elastic deformability of the polishing cloth 1 in the thickness direction D2, resulting in a decrease in the polishing rate and the likelihood of scratches. While conventional polishing cloths would have to be replaced frequently, the use of the polishing cloth of this embodiment extends the service life of a single polishing cloth and reduces the frequency of polishing cloth replacement during chemical mechanical polishing.

[0045] Thus, this specification includes the following disclosure: (1) A polishing cloth used in chemical mechanical polishing, The device comprises a substrate part made of a nonwoven fabric and a resin part made of a resin composition impregnated into the nonwoven fabric, The resin composition includes: Resin and and a resin part protecting agent that inhibits oxidation of the resin.

[0046] (2) the resin part protecting agent contains an antioxidant, an organic deposit containing the antioxidant adheres to the surface of the resin portion; The polishing cloth according to (1), wherein the total amount of the antioxidant attached to the surface of the resin portion and the antioxidant contained in the resin portion is 3 parts by mass or more per 100 parts by mass of the resin.

[0047] (3) The polishing cloth according to (2), wherein the antioxidant is a phenol-based antioxidant.

[0048] (4) The polishing cloth according to (3), wherein the phenol-based antioxidant is a hindered phenol-based antioxidant.

[0049] (5) the resin is a polyurethane resin, The polishing cloth according to (3) or (4), wherein the phenolic antioxidant is a phenolic antioxidant in which a substituted or unsubstituted hydroxyphenyl group is bonded to an isocyanuric acid skeleton.

[0050] (6) The polishing cloth according to any one of (1) to (5) above, which is used in chemical mechanical polishing using potassium permanganate as an oxidizing agent.

[0051] It should be noted that the polishing cloth disclosed above is merely a limited example, and the polishing cloth according to the present invention is not limited to the above-described form. Furthermore, the polishing cloth according to the present invention is not limited by the above-described effects. The polishing cloth according to the present invention can be modified in various ways without departing from the spirit and scope of the present invention. [Example]

[0052] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0053] <Preparation of Example Polishing Cloth> (Resin part protective agent) A resin protective agent for suppressing oxidation of the resin part was prepared, which was confirmed in advance to easily bleed out from the urethane resin. The details of the prepared resin protective agent are as follows: Resin part protection agent A Antioxidant (commercially available product: "ADEKA STAB AO-20", manufactured by ADEKA Corporation) Substance name: 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione

[0054] (Checking bleed-out properties) A first impregnation liquid containing a polyurethane resin dissolved in a water-soluble organic solvent was prepared, and the first impregnation liquid was wet-impregnated into a nonwoven fabric. Next, a second impregnation liquid containing methyl ethyl ketone, a urethane prepolymer, and a curing agent was prepared, and the nonwoven fabric, which had been wet-impregnated so that the fibers were coated with the polyurethane resin composition, was dry-impregnated with the second impregnation liquid to produce the polishing cloth of the example.

[0055] The first impregnation liquid did not contain resin part protective agent A, and only the second impregnation liquid contained resin part protective agent A. The second impregnation liquid contained a urethane prepolymer with PTMG as a structural unit, and MOCA was used as the curing agent.

[0056] The prepared polishing cloth was cut along a plane parallel to the thickness direction and the cross section was photographed using a scanning electron microscope. The results are shown in Figure 3a. As can be seen from Figure 3a, the polishing cloth of the example had powdery deposits on the surface of the resin part. The deposits were then washed away with an organic solvent, and the resulting liquid was evaporated to dryness. The precipitated powder was compared with the commercially available antioxidant used as resin part protective agent A by infrared spectroscopy (IR). The results are shown in Figure 4. The upper part of Figure 4 shows an infrared spectroscopy (IR) chart of the powder obtained from the polishing cloth, and the lower part of Figure 4 shows an infrared spectroscopy (IR) chart of the commercially available antioxidant used as resin part protective agent A. The infrared spectroscopy (IR) charts for both were generally consistent. This confirmed that the organic deposits contained resin part protective agent A.

[0057] <Preparation of a polishing cloth as a comparative example> A commercially available phenolic antioxidant, which is not expected to bleed out from urethane resin, was used as resin part protective agent B, and a polishing cloth was prepared in the same manner as in the Example. The prepared polishing cloth was cut along a plane parallel to the thickness direction, and the cross section was photographed using a scanning electron microscope. The results are shown in Figure 3b. As can be seen from Figure 3b, no powdery deposits, like those of the polishing cloth of the Example, were formed on the surface of the resin part of the polishing cloth of the Comparative Example.

[0058] <Verification of oxidation suppression function> (Examples 1 to 3) The polishing cloths of Examples 1 to 3 have an apparent density of 400 kg / m 3 The polishing cloth was prepared so that the resin content was 60% by mass. The resin content was calculated from the solids concentration (polyurethane resin content) of the first impregnation liquid of polyurethane resin and the solids concentration (prepolymer + MOCA) of the second impregnation liquid. Three polishing cloths with a resin content of 60% by mass were prepared, each containing 2.3 parts by mass (Example 1), 6.9 parts by mass (Example 2), and 11.5 parts by mass (Example 3) of resin protective agent A per 100 parts by mass of polyurethane resin. As mentioned above, resin protective agent A was added only to the second impregnation liquid.

[0059] (Comparative Examples 1 to 3) Three types of polishing cloths, Comparative Examples 1 to 3, were prepared in the same manner as Examples 1 to 3, except that the aforementioned resin part protective agent B was used instead of resin part protective agent A, and the amount of resin part protective agent B was 2.3 parts by mass (Comparative Example 1), 6.9 parts by mass (Comparative Example 2), and 11.5 parts by mass (Comparative Example 3) per 100 parts by mass of polyurethane resin.

[0060] Examples 1 to 4 The apparent density of the polishing cloth is approximately 500 kg / m 3 A polishing pad was prepared in the same manner as in Example 3 (11.9 parts by mass of resin part protective agent A) except that the mass proportion of the resin part was changed from 60% by mass to 68% by mass.

[0061] (evaluation) An aqueous potassium permanganate solution was prepared, and the polishing cloths of each Example and Comparative Example were immersed in it. Since manganese oxide adheres to the resin when it is oxidized, increasing the mass of the polishing cloth, the effect of inhibiting oxidation was verified by observing the change in mass before and after immersion. The results are shown in the table below.

[0062] [Table 1]

[0063] From the above results, it was confirmed that resin part protective agent B had a lower ability to inhibit resin oxidation than resin part protective agent A. Furthermore, a polishing cloth serving as a reference example was prepared in the same manner as in Example 1 without adding a resin part protective agent (antioxidant), and evaluation was carried out in a potassium permanganate aqueous solution in the same manner as above. It was confirmed that the results were not significantly different from those of the comparative example. On the other hand, it was confirmed that oxidation was inhibited in the examples by comparison. Furthermore, from the above results, it was observed that the oxidation inhibition effect in the examples was more pronounced when the resin part protective agent was added in an amount exceeding 1 part by mass, and when the amount was increased to 2 parts by mass or more. From the above, it can be seen that the present invention can extend the service life of a polishing cloth. [Explanation of symbols]

[0064] 1: abrasive cloth, 1r: recess, 1s: polishing surface, 11: Base material part, 12, Resin part, 13: Cavity part

Claims

1. A polishing cloth used in chemical mechanical polishing, The device comprises a substrate part made of a nonwoven fabric and a resin part made of a resin composition impregnated into the nonwoven fabric, The resin composition includes: Resin and and a resin part protecting agent that inhibits oxidation of the resin.

2. the resin part protecting agent contains an antioxidant, an organic deposit containing the antioxidant adheres to the surface of the resin portion; 2. The polishing cloth according to claim 1, wherein the total amount of the antioxidant attached to the surface of the resin portion and the antioxidant contained in the resin portion is 3 parts by mass or more per 100 parts by mass of the resin.

3. 3. The polishing cloth according to claim 2, wherein the antioxidant is a phenolic antioxidant.

4. 4. The polishing cloth according to claim 3, wherein the phenolic antioxidant is a hindered phenolic antioxidant.

5. the resin is a polyurethane resin, 4. The polishing cloth according to claim 3, wherein the phenolic antioxidant is a phenolic antioxidant having a substituted or unsubstituted hydroxyphenyl group bonded to an isocyanuric acid skeleton.

6. 2. The polishing cloth according to claim 1, which is used in chemical mechanical polishing using potassium permanganate as an oxidizing agent.

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