Grinding composition

Abstract

To provide a novel polishing composition. [Solution] An abrasive composition comprising a water-soluble polymer, wherein the water-soluble polymer comprises at least a vinyl alcohol-based resin having a viscosity of 15 mPa·s or more in a 4% aqueous solution at 20°C.

Description

[Technical Field]

[0001] This invention relates to a novel polishing composition, and the like. [Background technology]

[0002] The surface of silicon wafers, used as components in semiconductor devices, is generally finished to a high-quality mirror surface through a lapping process (rough polishing process) and a polishing process (precision polishing process). The polishing process typically includes a primary polishing process (first polishing process) and a final polishing process (final polishing process).

[0003] In such polishing processes, polishing compositions are used. Polishing compositions containing water-soluble polymers are known, and for example, Patent Document 1 describes a polishing composition containing hydroxyethylcellulose and / or polyvinyl alcohol and a block-type polyether. Furthermore, Patent Document 2 discloses a semiconductor wetting agent containing a water-soluble polymer (such as hydroxyethylcellulose, polyvinyl alcohol, or polyvinylpyrrolidone) whose viscosity in a 0.3% by weight aqueous solution is less than 10 mPa·s at 25°C. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2005-85858 [Patent Document 2] Japanese Patent Publication No. 2010-34509 [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a novel polishing composition.

[0006] Another object of the present invention is to provide a polishing composition that can reduce the AFM roughness (roughness measured by AFM) of a surface after polishing (in particular, polishing of a semiconductor substrate such as a silicon wafer).

[0007] Another object of the present invention is to provide a polishing composition that gives a small haze on the surface after the polishing.

[0008] Still another object of the present invention is to provide a method for producing a polished article using such a polishing composition. [Means for Solving the Problems]

[0009] The present inventors focused on the AFM roughness of the surface of a substrate such as a semiconductor substrate after polishing, and as a result, found that when the surface of a semiconductor substrate is polished using a polishing composition containing a water-soluble polymer, the AFM roughness of the polished surface may increase depending on the type of the water-soluble polymer.

[0010] As a result of extensive and intensive studies to solve the above problems, the present inventors have found that the AFM roughness of the surface of a semiconductor substrate after polishing can be reduced, for example, by using a polishing composition containing a specific water-soluble polymer and the like.

[0011] That is, the present invention relates to the following inventions and the like. [1] A polishing composition containing a water-soluble polymer, wherein the water-soluble polymer contains at least a vinyl alcohol-based resin having a 4% aqueous solution viscosity at 20°C of 15 mPa·s or more. [2] The polishing composition according to [1], wherein the saponification degree of the water-soluble polymer is 80 to 99.9 mol%. [3] The polishing composition according to [1] or [2], further comprising abrasive grains. [4] The polishing composition according to [3], wherein the abrasive grains contain silica. [5] The composition according to any one of [1] to [4], wherein the ratio of the monomer having an acid group to the total monomers of the water-soluble polymer is less than 0.1 mol%. [6] The polishing composition according to any one of [1] to [5], further comprising a pH adjuster. [7] The polishing composition according to any one of [1] to [6], further comprising abrasive grains and a pH adjuster, wherein the abrasive grains contain silica, and the pH adjuster contains a basic compound. [8] The polishing composition according to any one of [1] to [7], further comprising a surfactant. [9] The polishing composition further comprising a surfactant, wherein the surfactant contains at least one selected from a copolymer having an oxyethylene-oxypropylene structure and a polyoxyethylene alkyl ether, according to any one of [1] to [8].

[10] The polishing composition further comprising a surfactant, wherein the mass ratio of the water-soluble polymer to the surfactant is from 1:0.01 to 1:200, according to any one of [1] to [9].

[11] The polishing composition according to any one of [1] to

[10] , further comprising a solvent containing at least water, wherein the concentration of the water-soluble polymer is 1 ppm or more.

[12] The polishing composition according to any one of [1] to

[11] , further comprising a solvent containing at least water, wherein the solid content concentration is 0.01 mass% or more.

[13] A method for producing a polished article, comprising a step of polishing the surface of a polishing target object with the polishing composition according to any one of [1] to

[12] .

[14] The method for producing a polished article according to

[13] , comprising a dilution step of diluting the polishing composition with a solvent containing at least water, wherein in the polishing step, polishing is performed with the diluted liquid obtained in the dilution step.

[15] A method for reducing AFM roughness on a surface after polishing, comprising the step of polishing the surface of an object to be polished with an polishing composition described in any of [1] to

[12] .

[16] A method for reducing haze on a surface after polishing, comprising the step of polishing the surface of an object to be polished with an polishing composition described in any of [1] to

[12] . [Effects of the Invention]

[0012] According to the present invention, a novel polishing composition can be provided. Such a composition can reduce AFM roughness (especially long-wavelength roughness) on the surface after polishing (particularly polishing semiconductor substrates such as silicon wafers), thereby enabling the production of polished products with high-quality surfaces. Furthermore, it allows for efficient focusing during exposure in semiconductor device fabrication.

[0013] Furthermore, such a composition can reduce the haze on the surface after polishing, making it possible to obtain a polished product with a high-quality surface.

[0014] Furthermore, such compositions allow for the efficient formation of semiconductor devices and the like.

[0015] Furthermore, the present invention provides a method for producing polished products using the above-described composition. [Modes for carrying out the invention]

[0016] (composition) The compositions of the present invention typically contain certain water-soluble polymers as described below. These compositions can be used, in particular, for polishing.

[0017] (Water-soluble polymer) The water-soluble polymer may contain a vinyl alcohol-based resin (hereinafter sometimes referred to as vinyl alcohol-based resin (A)) whose viscosity in a 4% aqueous solution at 20°C is 15 mPa·s or higher.

[0018] (Vinyl alcohol-based resin (A)) Vinyl alcohol-based resins are typically polyvinyl alcohol-based resins (sometimes called PVA-based resins or PVA), and are saponified products of vinyl ester polymers (polymers in which at least vinyl ester is the polymerization component).

[0019] The vinyl ester (vinyl ester monomer) is not particularly limited, but for example, fatty acid vinyl esters [e.g., vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprylate, vinyl versatate, vinyl monochloroacetate, etc.] 1-30 fatty acid vinyl esters (for example, C 1-16 Alkanate-vinyl esters, etc.], aromatic vinyl carboxylates [for example, vinyl benzoate and other arene carboxylates (for example, C 7-12 Examples include arene carboxylic acid-vinyl esters, etc.

[0020] Vinyl esters may be used individually or in combination of two or more types.

[0021] Vinyl esters include at least fatty acid vinyl esters (e.g., vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, etc.). 1-10 It is preferable that it contains alkanic acid-vinyl esters, and from an industrial standpoint, it may particularly contain vinyl acetate.

[0022] Vinyl ester polymers may, if necessary, contain units derived from other monomers (monomers copolymerizable with vinyl esters) (they may be modified with other monomers).

[0023] Other monomers are not particularly limited, but include, for example, alkyl vinyl ethers (e.g., C23-3 1-30 Alkyl vinyl ether, preferably C 1-16Alkyl vinyl ethers), epoxy group-containing vinyl monomers {e.g., vinyl glycidyl ethers (e.g., allyl glycidyl ether, (meth)acryl glycidyl ether, 4-(meth)acrylamide phenyl glycidyl ether, 3-(meth)acrylamide phenyl glycidyl ether, N-glycidoxymethyl (meth)acrylamide, N-glycidoxyethyl (meth)acrylamide, N-glycidoxypropyl (meth)acrylamide, N-glycidoxybutyl (meth)acrylamide, 4-(meth)acrylamide methyl-2,5-dimethyl-phenyl glycidyl ether), epoxy group-containing α-olefins (e.g., 1,2-epoxy-5-hexene, 1,2-epoxy-7-octene, 1,2-epoxy-9-decene, 8-hydroxy-6,7-epoxy-1-octene, 8-acetoxy-6,7-epoxy-1-octene), N-(2,3-epoxy)propyl (meth)acrylamide, (meth)acrylamide propyl dimethyl (2,3-Epoxy)propylammonium chloride, glycidyl (meth)acrylate, etc., α-olefins (e.g., ethylene, propylene, etc.), (meth)acrylic acid esters [e.g., alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, diacetone (meth)acrylate], unsaturated amides [e.g., (meth)acrylamide, diacetone (meth)acrylamide, N-methylolacrylamide, etc.], unsaturated acids {e.g., unsaturated acids [e.g., (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, etc.], unsaturated acid esters [unsaturated acids other than (meth)acrylic acid] Examples include, but are not limited to, alkyl (methyl, ethyl, propyl, etc.) esters, unsaturated anhydrides (maleic anhydride, etc.), salts of unsaturated acids (e.g., alkali metal salts (e.g., sodium salts, potassium salts, etc.), ammonium salts, etc.), glycidyl group-containing monomers (e.g., allyl glycidyl ether, glycidyl (meth)acrylate, etc.), sulfonic acid group-containing monomers (e.g., 2-acrylamido-2-methylpropanesulfonic acid, its salts, etc.), phosphate group-containing monomers (e.g., acid phosphooxyethyl (meth)acrylate, acid phosphooxypropyl (meth)acrylate, etc.), allyl alcohol, diacetone (meth)acrylamide, etc.

[0024] Other monomers may be used individually or in combination of two or more.

[0025] Units derived from vinyl esters or other monomers may be modified to the extent that they do not impair the effects of the present invention.

[0026] Modification of vinyl ester-derived units may include, for example, acetalization, etherification, acetoacetylation, cationization, anionization (e.g., carboxyl group modification, sulfonic acid group modification, etc.), and polyoxyalkylene modification (e.g., ethylene oxide group modification).

[0027] Modification of units derived from other monomers may include, for example, ring-opening reactions of epoxy groups (e.g., reactions of epoxy groups with thiols).

[0028] The modification method is not particularly limited, but examples of acetoacetylation methods for vinyl ester-derived units include reacting a vinyl alcohol-based resin with a diketene. The method for reacting vinyl alcohol resin with diketene is not particularly limited, and examples include directly reacting vinyl alcohol resin with gaseous or liquid diketene, pre-adsorbing an organic acid onto the vinyl alcohol resin and then spraying gaseous or liquid diketene under an inert gas atmosphere to cause a reaction, and spraying a mixture of organic acid and liquid diketene onto the vinyl alcohol resin to cause a reaction.

[0029] Examples of ring-opening reactions of epoxy groups in units derived from other monomers include methods of reacting units derived from epoxy group-containing vinyl monomers with thiols [for example, thiols having an amino group (such as the thiol described in Japanese Patent No. 3647630)] (for example, the method described in Japanese Patent No. 3647630).

[0030] The vinyl alcohol-based resin (A) may be used individually or in combination of two or more types.

[0031] Furthermore, commercially available vinyl alcohol-based resins (A) may be used.

[0032] The method for producing the vinyl alcohol-based resin (A) is not particularly limited, and known methods such as saponification of a vinyl ester polymer may be used. The polymerization method for vinyl ester polymers is not particularly limited, and examples include conventionally known bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. However, solution polymerization (for example, solution polymerization using methanol as a solvent) is industrially preferred. In this solution polymerization, known initiators such as peroxide-based and azo-based initiators can be used, and the degree of polymerization of the resulting vinyl ester polymer can be adjusted by changing the mixing ratio of the vinyl ester monomer and the solvent, and the polymerization yield.

[0033] Conventional saponification methods using alkaline catalysts or acid catalysts can be used for saponifying vinyl ester polymers. Among these, a method of alcohol decomposition by adding an alkali such as sodium hydroxide to a methanol solution of the vinyl ester polymer or a mixed solution of the vinyl ester polymer with methanol, water, methyl acetate, etc., and stirring the mixture is industrially preferred. Subsequently, the obtained lump, gel, or granular material may be crushed, the added alkali may be neutralized as needed, the solid and liquid components may be separated, and the solid material may be dried to obtain a PVA-based resin. Furthermore, when modification is performed, the timing of the modification is not particularly limited and may be before or after the saponification of the vinyl ester polymer.

[0034] Typical vinyl alcohol-based resins (A) include, for example, saponified vinyl ester polymers in which vinyl ester is at least one polymerization component. Furthermore, the vinyl alcohol-based resin (A) may be modified (for example, by the above modification) or may have a modifying group. As described above, it may be a modified resin in which units derived from vinyl esters or other monomers have been modified, or it may be a resin in which monomers having a modifying group have been used.

[0035] The viscosity of a 4% aqueous solution of vinyl alcohol-based resin (A) at 20°C is typically 15 mPa·s or higher (for example, 18 mPa·s or higher, 20 mPa·s or higher, 22 mPa·s or higher, 25 mPa·s or higher, 30 mPa·s or higher, 40 mPa·s or higher, 50 mPa·s or higher, 60 mPa·s or higher, 70 mPa·s or higher, 80 mPa·s or higher, 90 mPa·s or higher), and preferably 100 mPa·s or higher (for example, 110 mPa·s or higher, 120 mPa·s or higher, 130 mPa·s or higher, 140 mPa·s or higher). It may be mPa·s or higher, more preferably 150 mPa·s or higher (for example, 160 mPa·s or higher, 170 mPa·s or higher, 180 mPa·s or higher, 190 mPa·s or higher), and even more preferably 200 mPa·s or higher (for example, 210 mPa·s or higher, 220 mPa·s or higher, 230 mPa·s or higher, 240 mPa·s or higher, 250 mPa·s or higher, 260 mPa·s or higher, 270 mPa·s or higher, 280 mPa·s or higher, 290 mPa·s or higher, 300 mPa·s or higher), etc. In this invention, the viscosity of a 4% aqueous solution of vinyl alcohol resin (A) at 20°C may be relatively high, from the viewpoint of easily reducing AFM roughness and haze on the surface after polishing (especially polishing semiconductor substrates such as silicon wafers). In particular, when the degree of saponification of the vinyl alcohol-based resin (A) is 98.0 mol% or more (for example, 98.0 to 99.9 mol%), the viscosity of a 4% aqueous solution of the vinyl alcohol-based resin (A) at 20°C may be, for example, 40 mPa·s or more (for example, 50 mPa·s or more), preferably 60 mPa·s or more (for example, 70 mPa·s or more). Furthermore, when the degree of saponification of the vinyl alcohol-based resin (A) is around 88 mol% (for example, 85-90 mol%), the viscosity of a 4% aqueous solution of the vinyl alcohol-based resin (A) at 20°C may be, for example, 180 mPa·s or more (for example, 190 mPa·s or more), preferably 200 mPa·s or more (for example, 210 mPa·s or more), and more preferably 220 mPa·s or more (for example, 230 mPa·s or more).

[0036] The upper limit of the viscosity of a 4% aqueous solution of vinyl alcohol-based resin (A) at 20°C is not particularly limited, but may be, for example, 3000 mPa·s or less, 2500 mPa·s or less, etc.

[0037] Furthermore, the viscosity of a 4% aqueous solution of vinyl alcohol-based resin (A) at 20°C may be set within an appropriate range (for example, 15-3000 mPa·s, 60-3000 mPa·s, 15-2500 mPa·s, 20-2500 mPa·s, 60-2500 mPa·s, etc.) by appropriately combining these upper and lower limits (the same applies to others), and all combinations of the above upper and lower limits are included.

[0038] The viscosity of a 4% aqueous solution of vinyl alcohol-based resin (A) at 20°C may be measured by, for example, the method specified in JIS K 6726 (1994).

[0039] The degree of saponification of the vinyl alcohol-based resin (A) is not particularly limited, but may be, for example, 60 mol% or more (e.g., 70 mol% or more), preferably 80 mol% or more (e.g., 81 mol% or more, 82 mol% or more, 83 mol% or more, 84 mol% or more, 85 mol% or more), and more preferably 90 mol% or more (e.g., 91 mol% or more, 92 mol% or more, 93 mol% or more, 94 mol% or more, 95 mol% or more, 96 mol% or more, 97 mol% or more, 98 mol% or more, 99 mol% or more).

[0040] The upper limit of the degree of saponification of the vinyl alcohol-based resin (A) is not particularly limited, but may be, for example, 99.9 mol% or less, 99.5 mol% or less, 99 mol% or less, 98 mol% or less, 97 mol% or less, 96 mol% or less, 95 mol% or less, etc.

[0041] Furthermore, the degree of saponification of the vinyl alcohol-based resin (A) may be set within an appropriate range (for example, 80 to 99.9 mol%) by appropriately combining these upper and lower limits (the same applies to others), and this range includes all combinations of the above upper and lower limits.

[0042] The degree of saponification of the vinyl alcohol-based resin (A) may be measured, for example, by the saponification degree measurement method specified in JIS K6726.

[0043] The average degree of polymerization of the vinyl alcohol-based resin (A) is not particularly limited, but may be, for example, 1700 to 12000, preferably 2000 to 11000, more preferably 3000 to 10000, and particularly preferably 4000 to 9000.

[0044] The average degree of polymerization of the vinyl alcohol-based resin (A) may be measured by, for example, the method specified in JIS K6726.

[0045] The composition may further contain other water-soluble polymers other than vinyl alcohol-based resin (A).

[0046] Other water-soluble polymers include, but are not limited to, vinyl alcohol resins not included in the range of vinyl alcohol resin (A), cellulose derivatives (e.g., methylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxyethylmethylcellulose, hydroxypropylmethylcellulose, ethylhydroxyethylcellulose, carboxymethylcellulose), starch derivatives (e.g., pullulan, cyclodextrin), imine derivatives [e.g., poly(N-acylalkyleneimine)], polyvinylpyrrolidone resins, polyvinylcaprolactam resins, acrylic resins, polyacryloylmorpholine resins, and polyoxyalkylenes (e.g., polyoxyethylene).

[0047] Other water-soluble polymers may be used individually or in combination of two or more.

[0048] As illustrated above, the water-soluble polymer may be modified to the extent that it does not hinder the effects of the present invention. However, the proportion of monomers having an acidic group (e.g., a carboxyl group) relative to the total monomers of the water-soluble polymer (or monomers constituting the water-soluble polymer) may be, for example, 5 mol% or less, 2 mol% or less (e.g., less than 2 mol%, 1 mol% or less, less than 1 mol%, 0.5 mol% or less, less than 0.5 mol%, 0.1 mol% or less, less than 0.1 mol%).

[0049] In the vinyl alcohol resin (A), the ratio of structural units having a modified group to the total amount of structural units derived from vinyl ester (and vinyl alcohol) and structural units derived from monomers having a modified group (or structural units having a modified group) is preferably less than 0.1 mol%, more preferably less than 0.01 mol%, and even more preferably less than 0.001 mol%. In the cation-modified vinyl alcohol resin (A), the ratio of structural units having a cationic group to the total amount of structural units derived from vinyl ester (and vinyl alcohol) and structural units having a cationic group may preferably be less than 0.01 mol%, more preferably less than 0.001 mol%, and even more preferably 0.0005 mol% or less. In the anionic modified vinyl alcohol resin (A), the ratio of structural units having anionic groups to the total amount of structural units derived from vinyl ester (and vinyl alcohol) and structural units having anionic groups is preferably less than 0.1 mol%, more preferably 0.01 mol% or less, and even more preferably 0.001 mol% or less. In the ethylene oxide group-modified vinyl alcohol resin (A), the ratio of structural units having ethylene oxide groups to the total amount of structural units derived from vinyl ester (and vinyl alcohol) and structural units having ethylene oxide groups may preferably be 5 mol% or less, more preferably 3 mol% or less, and even more preferably 1 mol% or less.

[0050] (Surfactants) The composition may further contain a surfactant. The use of a surfactant can improve the dispersion stability of the composition. In addition, the AFM roughness and haze of the polished surface can be easily reduced.

[0051] The molecular weight of the surfactant is 1×10 from the viewpoints of the dispersibility of the composition, the cleanability of the object to be polished, and the like 4 The following is preferable. Moreover, the lower limit of the molecular weight of the surfactant can be appropriately selected depending on the type of the surfactant and the like, and is, for example, 200 or more, preferably 250 or more from the viewpoint of haze reduction and the like, more preferably 300 or more (e.g., 500 or more), further preferably 2000 or more, and particularly preferably 5000 or more.

[0052] Specifically, the molecular weight of the surfactant may be, for example, 200 to 10000, preferably 250 to 10000, more preferably 300 to 10000 (e.g., 2000 to 10000, 5000 to 10000), and the like.

[0053] As the molecular weight of the surfactant, a weight average molecular weight (Mw) determined by GPC (aqueous system, converted to polyethylene glycol) or a molecular weight calculated from a chemical formula can be adopted.

[0054] The surfactant may be a water-soluble polymer having a molecular weight within the ranges exemplified above (for example, other water-soluble polymers exemplified above).

[0055] Specific examples of the surfactant include anionic surfactants and nonionic surfactants, and nonionic surfactants are preferred from the viewpoints of low foaming property, ease of pH adjustment, and the like.

[0056] Examples of the nonionic surfactant include copolymers of a plurality of oxyalkylenes (for example, a plurality of oxyC such as diblock type, triblock type, random type, and alternating type 2-6 alkylene, preferably oxyC 2-3(Alkylene copolymers), oxyalkylene polymers (e.g., polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.), polyoxyalkylene adducts {e.g., polyoxyethylene adducts [e.g., polyoxyethylene alkyl ethers (e.g., polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxyethylene oleyl ether), polyoxyethylene phenyl ether, polyoxyethylene alkylphenyl ether (e.g., polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene dodecylphenyl ether), polyoxyethylene styrenated phenyl ether, polyoxyethylene alkylamines (e.g., polyoxyethylene laurylamine, polyoxyethylene stearylamine, polyoxyethylene oleylamine), polyoxyethylene alkylamides (e.g., polyoxyethylene stearylamide, polyoxyethylene oleylamide), polyoxyethylene fatty acid esters (e.g., polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate, polyoxyethylene monooleate, polyoxyethylene dioleate), polyoxyethylene glyceryl ether fatty acid esters, polyoxyethylene sorbitan fatty acid esters (e.g., polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopaltimate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate), polyoxyethylene sorbitan tetraoleate, polyoxyethylene castor oil,Polyoxyethylene hydrogenated castor oil and other polyoxy C 2-6 Alkylene adducts, preferably polyoxy C 2-3 Examples include alkylene adducts and acetylene glycol-based surfactants [for example, alkylene oxide (e.g., ethylene oxide) adducts of acetylene glycol].

[0057] Examples of copolymers of multiple types of oxyalkylenes include copolymers having an oxyethylene (EO) structure and an oxypropylene (PO) structure (polymers having an EO-PO structure) {for example, block copolymers of EO and PO [for example, diblocks, polyoxyethylene (PEO)-polyoxypropylene (PPO)-PEO type triblocks, PPO-PEO-PPO type triblocks, etc.], random copolymers of EO and PO, etc.}.

[0058] Among these nonionic surfactants, copolymers having an EO-PO structure, polyoxyethylene alkyl ethers, and acetylene glycol-based surfactants are preferred, with block copolymers of EO and PO (especially PEO-PPO-PEO type triblocks), random copolymers of EO and PO, and polyoxyethylene alkyl ethers (e.g., polyoxyethylene decyl ethers) being particularly preferred.

[0059] As the PEO-PPO-PEO type triblock, a polymer represented by the following general formula (2) can be preferably used. HO-(EO)a-(PO)b-(EO)cH···(2) In general formula (2), EO represents an oxyethylene unit (-CH2CH2O-), PO represents an oxypropylene unit (-CH2CH(CH3)O-) group, and a, b, and c are integers of 1 or more (typically 2 or more). In general formula (2), the sum of a and c is preferably in the range of 2 to 1000, more preferably in the range of 5 to 500, and even more preferably in the range of 10 to 200. In general formula (2), b is preferably in the range of 2 to 200, more preferably in the range of 5 to 100, and even more preferably in the range of 10 to 50.

[0060] In a block copolymer or random copolymer of EO and PO, the molar ratio (EO / PO) of EO and PO constituting the copolymer is preferably greater than 1, more preferably 2 or more, and even more preferably 3 or more (for example, 5 or more) from the viewpoint of solubility in water and washability.

[0061] Furthermore, as an acetylene glycol-based surfactant, for example, Surfinol 400 series manufactured by Nisshin Chemical Industry Co., Ltd. can be used.

[0062] Surfactants may be used individually or in combination of two or more types.

[0063] The HLB value of the surfactant is not particularly limited, but may be, for example, 8 to 20, preferably 10 to 20, and more preferably 15 to 20.

[0064] (Abrasive grains) The composition may contain abrasive particles. The abrasive particles are not particularly limited, but examples include inorganic particles [e.g., inorganic oxides {e.g., metal oxides (e.g., alumina, cerium oxide, chromium oxide, titanium dioxide, zirconium oxide, magnesium oxide, manganese dioxide, zinc oxide, red iron oxide)}, metalloid oxides (e.g., silica)}, metal hydroxides [e.g., rare earth metal hydroxides (e.g., cerium hydroxide), zirconium hydroxide], inorganic nitrides (e.g., silicon nitride, boron nitride), inorganic carbides (e.g., silicon carbide, boron carbide), inorganic carbonates {e.g., alkali metal carbonates (e.g., sodium carbonate, potassium carbonate), alkaline earth metal carbonates (e.g., calcium carbonate, barium carbonate) and other metal carbonates}, diamond, etc.], organic particles [e.g., polymers of unsaturated acids (e.g., poly(meth)acrylic acid), polymers of (meth)acrylic acid esters {e.g., alkyl poly(meth)acrylates (e.g., polymethyl methacrylate)}, polyacrylonitrile, etc.], organic-inorganic composite particles, etc.].

[0065] Among these abrasive grains, inorganic particles are preferred, inorganic oxides (e.g., metal oxides, metalloid oxides) are more preferred, and silica (e.g., colloidal silica, fumed silica, precipitated silica) is particularly preferred. Therefore, the abrasive grains may contain at least silica. When the abrasive grains contain silica, the proportion of silica in the abrasive grains may be, for example, 50% by weight or more (e.g., 60% by weight or more), 70% by weight or more (80% by weight or more), 90% by weight or more (95% by weight or more, 99% by weight or more), etc. Among silicas, colloidal silica and fumed silica are preferred from the viewpoint of achieving a surface with lower haze and less likely to cause scratches on the surface of the object to be polished. Colloidal silica is more preferred from the viewpoint of being able to suppress scratches, and high-purity colloidal silica is particularly preferred from the viewpoint of preventing metal contamination.

[0066] Abrasive grains may be used individually or in combination of two or more types.

[0067] The particle morphology of the abrasive grains is not particularly limited and may be primary particles, secondary particles, or a mixture of both. Preferably, it may be a form that includes at least secondary particles.

[0068] Average primary particle size D of abrasive grains P1 While not particularly limited, from the viewpoint of polishing speed and other factors, it may be, for example, 5 nm or more, preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more. Furthermore, from the perspective of reducing haze, the average primary particle size D of the abrasive grains P1 The wavelength may preferably be less than 100 nm, more preferably 50 nm or less, and even more preferably 40 nm or less.

[0069] Note that the average primary particle size D of the abrasive grains P1 You may also set an appropriate range (for example, 5nm to 50nm, 5nm to 40nm, etc.) by appropriately combining these upper and lower limits (the same applies to others).

[0070] Average primary particle size D of abrasive grains P1 For example, the specific surface area S(m²) measured by the BET method. 2 / g) to D P1 It can be calculated using the formula = 2720 / S(nm). The method for measuring the specific surface area is not particularly limited; for example, it can be measured using a surface area measuring device manufactured by Micromeritex, trade name "Flow Sorb II 2300".

[0071] Average secondary particle size D of abrasive grains P2 While not particularly limited, from the viewpoint of polishing speed and other factors, it may be, for example, 10 nm or more, and preferably 20 nm or more. Also, the average secondary particle size D of the abrasive grains P2 From the viewpoint of obtaining a higher polishing effect, the wavelength may more preferably be 30 nm or more, even more preferably 35 nm or more, and particularly preferably 40 nm or more (for example, greater than 40 nm).

[0072] Also, the average secondary particle size D of the abrasive grainsP2 From the viewpoint of being easily present in the polishing composition as particles of a size suitable for reducing minute defects, these particles may be, for example, less than 100 nm, preferably 90 nm or less, and more preferably 80 nm or less.

[0073] Note that the average secondary particle size D of the abrasive grains P2 You may also set an appropriate range (for example, 10nm to 90nm, 20nm to 80nm, etc.) by appropriately combining these upper and lower limits (the same applies to others).

[0074] Average secondary particle size D of abrasive grains P2 This can be measured using a laser diffraction scattering method with, for example, a "UPA-UT151" model manufactured by Nikkiso Co., Ltd., using an aqueous dispersion of the target abrasive particles (without water-soluble polymers) as the measurement sample.

[0075] Average secondary particle size D of abrasive grains P2 D is the average primary particle size of the abrasive grains. P1 Equivalent to or better than (D P2 / D P1 It is acceptable that ≥1, D P1 Larger than (D P2 / D P1 >1) It may also be something else. D of abrasive grains P2 / D P1 From the viewpoint of polishing effect and surface smoothness after polishing, it is preferable that the value be in the range of 1 to 3.

[0076] The shape (outer form) of the abrasive grains is not particularly limited, but may be spherical or non-spherical {for example, peanut-shaped (i.e., the shape of a peanut shell), cocoon-shaped, konpeito-shaped, or rugby ball-shaped}.

[0077] The average value of the major axis / minor axis ratio (average aspect ratio) of the primary particles of the abrasive grain is not particularly limited, but from the viewpoint of polishing speed and the like, it is preferably 1.0 or higher, more preferably 1.05 or higher, and even more preferably 1.1 or higher. Furthermore, the average aspect ratio of the abrasive grains is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less, from the viewpoint of reducing scratches.

[0078] The shape (outer shape) and average aspect ratio of abrasive grains can be determined, for example, by electron microscopy observation. Specifically, a scanning electron microscope (SEM) is used to draw the smallest rectangle circumscribing each grain image for a predetermined number of abrasive grains (e.g., 200) whose individual grain shapes can be recognized. For each drawn rectangle, the ratio of the major axis to the minor axis is calculated by dividing the length of the major side by the length of the minor side. The average aspect ratio can then be determined by taking the arithmetic mean of the aspect ratios of the predetermined number of grains.

[0079] (pH adjuster) The composition may contain a pH adjuster. As a pH adjuster, basic compounds are preferred from the viewpoint of chemical polishing of the surface of the object to be polished, improvement of polishing speed, and improvement of the dispersion stability of the composition. The pH of the composition can be increased by using basic compounds.

[0080] Examples of basic compounds include nitrogen-containing organic or inorganic basic compounds [e.g., quaternary ammonium hydroxide or its salts (e.g., tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, etc.)], ammonia, amines {e.g., methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N-(β-aminoethyl)ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, guanidine, etc.}, azoles (e.g., anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperazine, N-methylpiperazine, imidazole, triazole, etc.}), alkali metal or alkaline earth metal hydroxides (e.g., potassium hydroxide, sodium hydroxide, etc.), carbonates (e.g., ammonium carbonate, potassium carbonate, sodium carbonate, etc.), and bicarbonates (e.g., ammonium bicarbonate, potassium bicarbonate, sodium bicarbonate, etc.).

[0081] Among these basic compounds, from the viewpoint of improving polishing speed, ammonia, alkali metal hydroxides (e.g., potassium hydroxide, sodium hydroxide, etc.), quaternary ammonium hydroxides or their salts (e.g., tetramethylammonium hydroxide, tetraethylammonium hydroxide, etc.), carbonates (e.g., ammonium carbonate, potassium carbonate, sodium carbonate, etc.), and bicarbonates (e.g., ammonium bicarbonate, potassium bicarbonate, sodium bicarbonate, etc.) are preferred, ammonia, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, and tetraethylammonium hydroxide are more preferred, ammonia and tetramethylammonium hydroxide are even more preferred, and ammonia is particularly preferred.

[0082] Basic compounds may be used individually or in combination of two or more.

[0083] (solvent) The composition may contain a solvent. The solvent is not particularly limited, but examples include water and organic solvents (e.g., lower alcohols, lower ketones, etc.). The solvent preferably contains at least water. The water content in the total solvent is preferably 90% by volume or more, and more preferably 95% by volume or more (for example, 99-100% by volume).

[0084] As for the water, ion-exchanged water (deionized water), pure water, ultrapure water, distilled water, etc., can be preferably used. From the viewpoint of minimizing interference with the function of other components contained in the composition, it is preferable that the total content of transition metal ions in the water be 100 ppb or less. The water may be purified by methods such as removing impurity ions using ion exchange resin, removing foreign substances using a filter, or distillation.

[0085] (Other ingredients) In addition to the above-mentioned components (water-soluble polymer, abrasive particles, pH adjuster, surfactant, and solvent), the composition may also contain other components. Other ingredients, though not limited to them, include additives such as chelating agents, organic acids, organic acid salts, inorganic acids, inorganic acid salts, preservatives, and fungicides.

[0086] Examples of chelating agents include aminocarboxylic acid-based chelating agents and organic phosphonic acid-based chelating agents.

[0087] Examples of aminocarboxylic acid-based chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetic acid, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid, sodium diethylenetriaminepentaacetate, triethylenetetraminehexaacetic acid, and sodium triethylenetetraminehexaacetate.

[0088] Examples of organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri(methylenephosphonic acid), ethylenediaminetetrakis(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, and α-methylphosphonosuccinic acid.

[0089] Among these chelating agents, organic phosphonic acid chelating agents are more preferred, with ethylenediaminetetrakis(methylenephosphonic acid) and diethylenetriaminepenta(methylenephosphonic acid) being particularly preferred.

[0090] Examples of organic acids include fatty acids (e.g., formic acid, acetic acid, propionic acid), aromatic carboxylic acids (e.g., benzoic acid, phthalic acid), citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid, organic sulfonic acids, and organic phosphonic acids. Examples of organic acid salts include alkali metal salts of organic acids (e.g., sodium salts, potassium salts, etc.) and ammonium salts of organic acids.

[0091] Examples of inorganic acids include sulfuric acid, nitric acid, hydrochloric acid, and carbonic acid. Examples of inorganic salts include alkali metal salts of inorganic acids (e.g., sodium salts, potassium salts, etc.) and ammonium salts of inorganic acids.

[0092] Examples of preservatives and fungicides include isothiazolin compounds, parahydroxybenzoic acid esters, and phenoxyethanol.

[0093] Other ingredients may be used individually or in combination of two or more.

[0094] (Form of composition) The composition may be used as is as a polishing solution, as described later, or it may be used as a polishing solution after being diluted with a solvent (for example, diluted at the dilution ratio described later). In other words, the composition may be of low concentration (abrasive solution) or of high concentration (concentrated abrasive solution). Furthermore, a high-concentration composition may be a concentrate of a low-concentration composition.

[0095] In the composition, the proportion of water-soluble polymers (the proportion of water-soluble polymers to the total composition) is not particularly limited, but on a mass basis, it is, for example, 1 ppm or more, preferably 3 ppm or more, and more preferably 5 ppm or more (for example, 10 ppm or more) from the viewpoint of haze reduction. Furthermore, in the composition, the proportion of water-soluble polymer may be preferably 1000 ppm or less by mass, and more preferably 500 ppm or less (for example, 300 ppm or less), from the viewpoint of polishing speed and other factors. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and the proportion of water-soluble polymer in the composition may specifically be, for example, 1 ppm to 1000 ppm, preferably 3 ppm to 500 ppm, and more preferably 5 ppm to 300 ppm.

[0096] The proportion of water-soluble polymers is not particularly limited, but can be appropriately set according to the dilution ratio, for example, in high-concentration compositions. However, it may be, for example, 1000 ppm or more by mass, preferably 1500 ppm or more, and more preferably 2000 ppm or more. Furthermore, in high-concentration compositions, the proportion of water-soluble polymers may be preferably 20,000 ppm or less by mass, and more preferably 10,000 ppm or less. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and in high-concentration compositions, the proportion of water-soluble polymer may specifically be, for example, 1000 ppm to 20000 ppm, preferably 1500 ppm to 10000 ppm, and more preferably 2000 ppm to 5000 ppm.

[0097] When the composition contains abrasive grains, the proportion of abrasive grains in the composition (the proportion of abrasive grains to the total composition) is not particularly limited, but may be, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.1% by mass or more (for example, 0.15% by mass or more). A higher polishing speed can be achieved by increasing the abrasive grain content. Furthermore, in the composition, the proportion of abrasive grains may be, for example, 10% by mass or less, preferably 7% by mass or less, and more preferably 5% by mass or less, from the viewpoint of achieving a surface with lower haze. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and the proportion of abrasive grains in the composition may be, specifically, 0.01% to 10% by mass, preferably 0.05% to 7% by mass, and more preferably 0.1% to 5% by mass.

[0098] The proportion of abrasive particles can be appropriately set according to the dilution ratio, for example, in high-concentration compositions, and is not particularly limited, but may be, for example, 0.2% by mass or more, preferably 1% by mass or more, and more preferably 2% by mass or more. Furthermore, in high-concentration compositions, the proportion of abrasive grains may be, for example, 50% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and in high-concentration compositions, the proportion of abrasive grains may specifically be, for example, 0.2% to 50% by mass, 1% to 20% by mass, or 2% to 10% by mass.

[0099] If the composition contains a pH adjusting agent, the proportion of the pH adjusting agent in the composition (the proportion of the pH adjusting agent to the total composition) is not particularly limited, but from the viewpoint of polishing speed and other factors, it may be, for example, 1 ppm or more, preferably 5 ppm or more. Furthermore, the proportion of the pH adjusting agent in the composition may be, for example, less than 1000 ppm, preferably less than 500 ppm, from the viewpoint of reducing haze. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and the proportion of the pH adjusting agent in the composition may specifically be, for example, 1 ppm or more and less than 1000 ppm, or 5 ppm or more and less than 500 ppm.

[0100] The proportion of the pH adjuster can be appropriately set according to the dilution ratio, for example, in high-concentration compositions, and is not particularly limited, but may be, for example, 20 ppm or more, preferably 100 ppm or more. Furthermore, in high-concentration compositions, the proportion of the pH adjusting agent may be, for example, less than 20,000 ppm, preferably less than 10,000 ppm. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and in high-concentration compositions, the proportion of the pH adjusting agent may specifically be, for example, 20 ppm or more and less than 20,000 ppm, preferably 100 ppm or more and less than 10,000 ppm.

[0101] If the composition contains a surfactant, the proportion of the surfactant in the composition (the proportion of the surfactant to the total composition) is not particularly limited, but from the viewpoint of AFM roughness and haze reduction, for example, it may be 0.1 ppm or more, preferably 0.5 ppm or more, more preferably 1 ppm or more (e.g., 3 ppm or more), and even more preferably 5 ppm or more (e.g., 10 ppm or more). Furthermore, in the composition, the proportion of surfactant may be, for example, 1000 ppm or less, preferably 500 ppm or less (for example, 300 ppm or less), and more preferably 100 ppm or less, from the viewpoint of polishing speed and other factors. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and the proportion of surfactant in the composition may specifically be, for example, 0.1 ppm to 1000 ppm, preferably 0.5 ppm to 500 ppm, and more preferably 1 ppm to 100 ppm.

[0102] The proportion of surfactant can be appropriately set according to the dilution ratio, for example, in high-concentration compositions, and is not particularly limited, but may be, for example, 2 ppm or more, preferably 10 ppm or more, more preferably 20 ppm or more, and even more preferably 100 ppm or more. Furthermore, in high-concentration compositions, the proportion of surfactant may be, for example, 20,000 ppm or less, preferably 10,000 ppm or less, and more preferably 2,000 ppm or less. Furthermore, these upper and lower limits may be combined as appropriate to set a suitable range, and in high-concentration compositions, the proportion of surfactant may specifically be, for example, 2 ppm to 20,000 ppm, preferably 10 ppm to 10,000 ppm, and more preferably 20 ppm to 2,000 ppm.

[0103] The solid content concentration of the composition is not particularly limited, but for example, it may be 0.01% by mass or more, preferably 0.01% to 50% by mass, and more preferably 0.05% to 40% by mass.

[0104] Furthermore, the solid content concentration of the composition can be appropriately set according to the dilution ratio, etc., for example, in the case of a high-concentration composition, and is not particularly limited, but may be, for example, 1% by mass or more, preferably 2% to 50% by mass, and more preferably 5% to 25% by mass.

[0105] The solid content concentration can be expressed as the percentage by mass of the residue remaining in the composition after drying it at 105°C for 24 hours.

[0106] If the composition contains other components, the proportion of these other components (the proportion of the other components to the total composition) is not particularly limited, but may be, for example, 0.01 to 30% by mass, preferably 0.01 to 20% by mass, and more preferably 0.01 to 10% by mass.

[0107] Furthermore, the proportions of other components can be appropriately set according to the dilution ratio, for example, in high-concentration compositions, and are not particularly limited, but may be, for example, 0.2 to 60% by mass, preferably 0.2 to 40% by mass, and more preferably 0.2 to 20% by mass.

[0108] When the composition contains abrasive particles, the ratio of water-soluble polymer to abrasive particles in the composition is not particularly limited, but the ratio of water-soluble polymer to abrasive particles (mass ratio) may be, for example, 10:1 to 1:1000, preferably 5:1 to 1:500, and more preferably 1:1 to 1:100.

[0109] When the composition contains a surfactant, the ratio of the water-soluble polymer to the surfactant in the composition is not particularly limited, but the ratio of water-soluble polymer to surfactant (mass ratio) may be, for example, 1:0.01 to 1:200, preferably 1:0.01 to 1:100 (for example, 1:0.01 to 1:20, more preferably 1:0.05 to 1:15, and particularly preferably 1:0.1 to 1:10).

[0110] From the viewpoint of suppressing abrasive particle aggregation, the zeta potential of the composition is, for example, -0mV or less, preferably -5mV or less, and more preferably -10mV or less. From the viewpoint of polishing speed, it is, for example, -100mV or more, preferably -90mV or more, and more preferably -80mV or more. The zeta potential of the composition can be measured, for example, using an ultrasonic zeta potential meter DT-1202 manufactured by Dispersion Technology.

[0111] (Method of manufacturing the composition) The method for producing the composition is not particularly limited, and for example, the components contained in the composition may be mixed. The mixing may be carried out at room temperature or while heating. Furthermore, mixing may be carried out while stirring, or it may be done using a mixing device (for example, a vane-type agitator, ultrasonic disperser, homomixer, etc.). The mixing order of the components in the composition is not particularly limited; for example, all components may be mixed at once, or they may be mixed in an order set as appropriate.

[0112] The composition may be filtered during the manufacturing process. Filtration may involve filtering each component contained in the composition, or filtering a mixture of the components. The filtration method is not particularly limited; for example, filtration may be performed using a filter. Furthermore, filtration methods such as recirculating filtration may be used.

[0113] (polishing) Polished products can be manufactured by polishing the surface of an object to be polished with the composition. The surface to be polished may be either both sides or one side of the object to be polished. Furthermore, when polishing both sides of an object, both sides may be polished simultaneously, or one side at a time. The following describes a preferred embodiment of a method for polishing an object to be polished using a composition (a method for manufacturing polished products).

[0114] Examples of materials to be polished include metals or metalloids such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, and stainless steel, or their alloys; glassy materials such as quartz glass, aluminosilicate glass, and glassy carbon; ceramic materials such as alumina, silica, sapphire, silicon nitride, tantalum nitride, and titanium carbide; compound semiconductor substrate materials such as silicon carbide, gallium nitride, and gallium arsenide; and resin materials such as polyimide resin. Among these materials to be polished, those containing silicon (for example, single-crystal silicon substrates) are preferred. The object to be polished may be composed of multiple materials.

[0115] The object to be polished may have a coating formed on it, but in this invention, it is preferable to polish the substrate itself. Examples of coatings include polysilicon films, nitride films, and oxide films. The thickness of the coating may also be, for example, more than 100 nm. Furthermore, the surface to be polished may be a substrate in which a portion has been oxidized (for example, having a native oxide film with a thickness of 100 nm or less).

[0116] Furthermore, while the shape of the object to be polished is not particularly limited, it is preferable that it has flat surfaces, such as a plate or a polyhedron.

[0117] For polishing, the polishing solution may be the composition as is, or a solution obtained by diluting the composition with a solvent may be used. As the diluent, the solvents exemplified above can be used, and it is preferable that the solvent contains at least water (aqueous solvent). Furthermore, the diluent may be the same as the solvent contained in the composition (the type of solvent, or in the case of a mixed solvent, the mixing ratio of each component is the same), or it may be different. The dilution ratio may be, for example, 2 to 100 times in terms of volume (for example, 5 to 50 times, 20 to 50 times), preferably 10 to 30 times, and more preferably 15 to 25 times.

[0118] Furthermore, the polishing solution may have its pH adjusted using the pH adjusting agent exemplified above. The pH of the polishing solution can be adjusted as appropriate depending on the degree of saponification of the vinyl alcohol-based resin and the type of abrasive grains, and is not particularly limited, but may be, for example, 8.0 to 12.0 (e.g., 9.0 to 11.0) or 5.0 to 9.0 (e.g., 6.0 to 8.0). The above pH can be particularly preferably applied to polishing solutions used for polishing silicon wafers (e.g., polishing solutions for final polishing).

[0119] The polishing solution is supplied to the object to be polished, and polishing can be performed using conventional methods. The composition can be particularly preferably used for polishing semiconductor substrates (especially silicon wafers). The polishing process in which the composition is used is not particularly limited, but it is particularly suitable, for example, for final polishing of silicon wafers or for polishing processes upstream thereof. Final polishing typically refers to the last polishing step in the manufacturing process of the target object (i.e., a step after which no further polishing is performed). For example, it is effective to apply this method to the polishing of silicon wafers whose surface roughness has been prepared to 0.01 nm to 100 nm by an upstream process (typically the final polishing or the polishing immediately preceding it), and its application to the final polishing is particularly preferred.

[0120] For example, when performing final polishing of a silicon wafer, the silicon wafer, which has undergone a lapping process and primary and secondary polishing processes, may be set in a general polishing apparatus, and polishing fluid may be supplied to the surface (surface to be polished) of the silicon wafer through the polishing pad of the apparatus. For example, while continuously supplying the polishing fluid, the polishing pad may be pressed against the surface of the silicon wafer and the two may be moved relative to each other (for example, by rotation).

[0121] (Washing) The polished material obtained in the manner described above may be washed. Cleaning can be performed, for example, using a cleaning solution. The cleaning solution is not particularly limited, and when polishing a semiconductor substrate, for example, the SC-1 cleaning solution (a mixture of ammonium hydroxide (NH4OH), hydrogen peroxide (H2O2), and water (H2O)), which is common in the semiconductor field, can be used. Furthermore, the temperature of the cleaning solution can be, for example, room temperature to around 90°C.

[0122] (Abrasive) The present invention also includes polished products that form the following polished surfaces. The polished surface of such polished material was examined using an atomic force microscope in a field of view of 30 × 30 μm. 2 The root mean square height (Sq) measured is preferably less than 0.030 nm, and more preferably less than 0.028 nm.

[0123] The lower limit of the above root mean square height (Sq) is not particularly limited and may be, for example, 0.005 nm or more, 0.01 nm or more, etc.

[0124] The root mean square height (Sq) may also be measured by the method described in the examples below.

[0125] The haze on the polished surface of the polished material is, for example, 0.3 ppm or less (e.g., less than 0.3 ppm), preferably 0.25 ppm or less (e.g., less than 0.25 ppm, 0.01 ppm to 0.25 ppm), more preferably 0.20 ppm or less (e.g., less than 0.20 ppm, 0.01 ppm to 0.20 ppm), particularly preferably 0.15 ppm or less (e.g., less than 0.15 ppm, 0.01 ppm to 0.15 ppm), and most preferably 0.10 ppm or less (e.g., less than 0.10 ppm, 0.01 ppm to 0.10 ppm).

[0126] Furthermore, haze can be measured by methods such as those described in the examples below.

[0127] An abrasive having the polished surface described above can be obtained, for example, by polishing and cleaning an object to be polished using an abrasive composition containing a water-soluble polymer. As the water-soluble polymer, for example, a water-soluble polymer with relatively high viscosity (for example, a water-soluble polymer with a viscosity of 15 mPa·s or higher in a 4% aqueous solution at 20°C) may be used. As a water-soluble polymer, for example, a vinyl alcohol-based resin can be suitably used, and by using the vinyl alcohol-based resin (A), it is easy to efficiently obtain a polished product having the polished surface described above. [Examples]

[0128] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following embodiments, "parts" and "%" refer to "parts by mass" and "% by mass" respectively, unless otherwise specified.

[0129] The physical properties of the PVA used in the examples were evaluated using the following method.

[0130] (1) Viscosity of 4% aqueous solution: Determined according to JIS K 6726 (1994).

[0131] (2) Degree of saponification: Determined according to JIS K 6726 (1994).

[0132] (Synthesis Examples 1-4) Following the method described in Production Example 1 of Japanese Patent Publication No. 2013-153149, the polymerization conditions (mixture ratio, temperature, pressure, polymerization time, etc. during polymerization) and saponification conditions (temperature, time, etc. during saponification) were modified to obtain PVA with a viscosity of 4% and degree of saponification as shown in Table 1, thereby obtaining PVA-1 to PVA-4 as shown in Table 1.

[0133] (Example 1) A colloidal silica dispersion was prepared by adding ammonia water containing 29% ammonia (NH3) as a basic compound to an aqueous solution containing 1% colloidal silica with an average primary particle diameter of 35 nm as abrasive particles, and adjusting the pH to 10.0. To this colloidal silica dispersion, PVA-1 was added to the total volume of the solution to a concentration of 100 ppm to obtain a composition (abrasive solution). The silica content in the composition was 1%.

[0134] (Example 2) A composition was obtained in the same manner as in Example 1, except that a copolymer having an EO-PO structure (Wako Pure Chemical Industries, Ltd., polyoxyethylene polyoxypropylene glycol (160 E.O.) (30 P.O.)) was added to a colloidal silica dispersion to a concentration of 10 ppm in the total volume of the solution.

[0135] (Example 3) A composition was obtained in the same manner as in Example 1, except that PVA was changed to PVA-2.

[0136] (Example 4) A composition was obtained in the same manner as in Example 1, except that PVA was changed to PVA-3.

[0137] (Example 5) A composition was obtained in the same manner as in Example 1, except that a copolymer having an EO-PO structure (Wako Pure Chemical Industries, Ltd., polyoxyethylene polyoxypropylene glycol (160 E.O.) (30 P.O.)) was added to a colloidal silica dispersion to a total concentration of 10 ppm, and PVA was changed to PVA-3.

[0138] (Example 6) A composition was obtained in the same manner as in Example 1, except that PVA was changed to PVA-4.

[0139] (Example 7) A composition was obtained in the same manner as in Example 1, except that a copolymer having an EO-PO structure (Wako Pure Chemical Industries, Ltd., polyoxyethylene polyoxypropylene glycol (160 E.O.) (30 P.O.)) was added to a colloidal silica dispersion to a total concentration of 10 ppm, and PVA was replaced with PVA-4.

[0140] (Example 8) A composition was obtained in the same manner as in Example 1, except that PVA-6 was used, which was obtained by mixing PVA-4 and PVA-5 listed in Table 1 in a mass ratio of PVA-4:PVA-5 = 48:52.

[0141] (Comparative Example 1) A composition was obtained in the same manner as in Example 1, except that polyvinylpyrrolidone (Wako Pure Chemical Industries, Ltd., polyvinylpyrrolidone K90) was used as the water-soluble polymer.

[0142] <Polishing silicon wafers> The surface of the silicon wafer was polished using the polishing solution described in each example under the following conditions. As the silicon wafer, a monocrystalline silicon wafer with a diameter of 300 mm, a conductivity type of P-type, a crystal orientation of <100>, and a resistivity of 0.1 Ω·cm or more and less than 100 Ω·cm was used.

[0143] The polishing evaluation was performed in two stages, namely preliminary polishing for unifying the state of the front surface and finish polishing using the above composition, using a single-wafer polishing machine manufactured by Okamoto Machine Tool Works, Ltd., model "PNX-332B". [Preliminary Polishing Conditions] Polishing pad: nonwoven fabric Polishing liquid: colloidal silica solution adjusted to pH 11 with KOH Polishing load: 30 kPa Platen rotational speed: 50 rpm Head rotational speed: 50 rpm Polishing time: 3 minutes [Finish Polishing Conditions] Polishing pad: suede Polishing load: 15 kPa Platen rotational speed: 30 rpm Head rotational speed: 30 rpm Polishing time: 3 minutes

[0144] <Cleaning> The polished silicon wafer was cleaned using a mixed solution of NH₄OH, H₂O₂ and ultrapure water (SC1) (volume ratio of NH₄OH:H₂O₂:ultrapure water is 1:3:30).

[0145] <AFM Roughness Measurement> The surface of the cleaned silicon wafer was evaluated by an atomic force microscope (AFM). Three points at coordinates (0 mm, 0 mm), (75 mm, 0 mm), and (145 mm, 0 mm) were observed, and the field of view was 30×30 μm 2 . For the roughness parameter, after tilt correction in the X direction and Y direction, the root mean square height (Sq) was calculated, and the average of the three points was used as the evaluation guideline. The results are shown in Table 1 in the following three grades. A: less than 0.028 nm B: 0.028 nm or more and less than 0.030 nm C: 0.030 nm or more

[0146] <Haze Measurement> The haze (ppm) on the surface of the cleaned silicon wafer was measured in DWO mode using a wafer inspection system manufactured by KLA-Tencor, product name "SP3". The measurement results were evaluated on the following four-point scale. A: Less than 0.10 ppm B: 0.10 ppm or more and less than 0.20 ppm C: 0.20 ppm or higher, less than 0.30 ppm D: 0.30ppm or more

[0147] Table 1 shows the evaluation results for the examples and comparative examples.

[0148] [Table 1]

[0149] As shown in Table 1, the AFM roughness of the polished surface was reduced in the examples. Furthermore, in the embodiment, the haze on the polished surface was small. [Industrial applicability]

[0150] The composition of the present invention can reduce the AFM roughness of the object to be polished, and therefore allows for efficient processing of substrates with a protective film formed on their surface, making it extremely useful in industry.

Claims

[Claim 1] A polishing composition comprising a water-soluble polymer, wherein the water-soluble polymer comprises at least a vinyl alcohol-based resin having a viscosity of 15 mPa·s or more in a 4% aqueous solution at 20°C.

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