Dispersion and abrasive compositions

Abstract

The present invention relates to a dispersant and a polishing agent composition. In a chemical mechanical polishing dispersant used in surface planarization of at least either of an insulating layer and a wiring layer, a block copolymer (P) having a polymer block A and a polymer block B is contained. The block copolymer (P) is as described below. (1) The polymer block A has a structural unit derived from at least one selected from the group consisting of an amide group-containing vinyl monomer and an ester group-containing vinyl monomer, and the polymer block B has a structural unit having an ionic functional group. (2) The polymer blocks A, B have a structural unit having an ionic functional group, and the block copolymer (P) satisfies at least one of Condition I and Condition II. (3) The polymer blocks A, B have a structural unit derived from a vinyl monomer represented by Formula (1). Formula (1): CH2=CR 1 -C(=O)-NR 2 -R 3 .

Description

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application Nos. 2019-239687, 2019-239688 and 2019-239689, filed on December 27, 2019, and therefore incorporates the contents thereof. Technical Field

[0003] This invention relates to dispersant and abrasive compositions, and more particularly, to dispersant and abrasive compositions for chemical mechanical polishing in semiconductor manufacturing processes for planarizing the surface of at least one of insulating layers and wiring layers formed on a wafer. Background Technology

[0004] Chemical mechanical polishing (CMP) technology is important for achieving high-precision multilayer wiring formation and is used in various stages of semiconductor device manufacturing processes, including insulating film planarization, metal connector formation, and embedded wiring formation. In CMP, abrasive compositions are used to improve processing speed and accuracy. These abrasive compositions generally contain a water-soluble polymer as a dispersant, along with abrasive grains and water (see, for example, Patent Document 1).

[0005] Water-soluble polymers enhance the dispersibility of abrasive grains by adsorbing onto their surface, thereby suppressing surface defects on the workpiece. Furthermore, by adsorbing onto the workpiece surface, water-soluble polymers hydrophilize the grinding surface, increasing the contact frequency between the abrasive grains and the grinding surface, thus contributing to increased processing speed. On the other hand, water-soluble polymers protect the surface of the workpiece, thereby also inhibiting excessive grinding. Furthermore, they can be expected to suppress the adhesion of abrasive grains and foreign matter, resulting in high-precision surface smoothing of the workpiece.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2017-17177 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] By including a water-soluble polymer as a dispersant in the polishing slurry composition, the surface of the workpiece can be smoothed with high precision. However, sometimes a single water-soluble polymer molecule adsorbs onto the surface of multiple abrasive grains in a bridging manner, causing abrasive grain aggregation. Such agglomerated structures caused by bridging between abrasive grains tend to be more easily generated under strong shear forces. In particular, when using cerium oxide as abrasive grains, if strong shear forces are applied, the contact frequency between abrasive grains increases, making abrasive grain aggregation more likely. To achieve high-precision surface smoothing of wiring layers and insulating layers in semiconductor manufacturing processes, it is necessary to further improve the dispersion stability of abrasive grains and suppress abrasive grain aggregation caused by shear forces.

[0011] The present invention was made in view of the above circumstances, and its object is to provide a dispersant with high dispersion stability of abrasive particles and the ability to suppress abrasive particle aggregation caused by shear force.

[0012] Methods for solving problems

[0013] In order to solve the above-mentioned problems, the inventors conducted in-depth research, focusing on block copolymers with specific structures. They discovered that, based on these block copolymers, the above-mentioned problems can be solved. According to the present invention, the following means are provided.

[0014] [1] A dispersant for use in the planarization of at least one of an insulating layer and a wiring layer for chemical mechanical polishing, the dispersant comprising a block copolymer (P) having a polymer block A and a polymer block B, the polymer block A having a structural unit UA derived from at least one of a vinyl monomer containing an amide group and a vinyl monomer containing an ester group, and the polymer block B having a structural unit UB having an ionic functional group.

[0015] [2] According to the dispersant of [1] above, wherein the structural unit UA comprises a structural unit derived from the vinyl monomer shown in the following formula (1);

[0016] CH2=CR 1 -C(=O)-NR 2 -R 3 …(1)

[0017] (In equation (1), R) 1 R is a hydrogen atom or a methyl group. 2 and R 3 Each is independently a hydrogen atom, or a substituted or unsubstituted monovalent hydrocarbon group, or R 2 With R 3 For mutual bonding with R 2 and R 3 The bonded nitrogen atoms together form a ring group.

[0018] [3] A dispersant for chemical mechanical polishing used in surface planarization of at least one of an insulating layer and a wiring layer, the dispersant comprising a block copolymer (P) having polymer block A and polymer block B, each of the superimposed block A and the polymer block B having a structural unit having an ionic functional group, the block copolymer (P) being a polymer satisfying at least one of conditions I and II below;

[0019] Condition I: The ionic functional groups of polymer block A are different from those of polymer block B;

[0020] Condition II: The content of ionic functional groups in polymer block A is different from the content of ionic functional groups in polymer block B.

[0021] [4] A dispersant for chemical mechanical polishing used in surface planarization of at least one of an insulating layer and a wiring layer, the dispersant comprising a block copolymer (P) having polymer block A and polymer block B, each of the polymer block A and the polymer block B having a structural unit derived from a vinyl monomer represented by the following formula (1).

[0022] CH2=CR 1 -C(=O)-NR 2 -R 3 …(1)

[0023] (In equation (1), R) 1 R is a hydrogen atom or a methyl group; 2 and R 3 Each is independently a hydrogen atom, or a substituted or unsubstituted monovalent hydrocarbon group, or R 2 With R 3 For mutual bonding with R 2 and R 3 The bonded nitrogen atoms together form a ring group.

[0024] [5] According to the dispersant of [4] above, wherein the polymer block A comprises a structural unit having at least one of a primary amide group and a hydroxyl group as a structural unit derived from the vinyl monomer shown in formula (1) above.

[0025] [6] According to the dispersant of [4] or [5] above, wherein the polymer block B comprises a structural unit having at least one of a secondary amide group and a tertiary amide group as a structural unit derived from the vinyl monomer shown in the above formula (1).

[0026] [7] The dispersant according to any one of [4] to [6] above, wherein the polymer block B comprises a structural unit having a carboxyl group.

[0027] [8] The dispersant according to any one of [1] to [7] above, wherein the ratio (A / B) of the polymer block A to the polymer block B in the block copolymer (P) is 10 / 90 to 90 / 10 by mass.

[0028] [9] The dispersant according to any one of [1] to [8] above, wherein the polymer block B further comprises a structural unit having an alkyl group having 1 to 10 carbon atoms in the side chain portion.

[0029]

[10] The dispersant according to any one of [1] to [9] above, wherein the molecular weight dispersion (Mw / Mn), expressed as the ratio of the number average molecular weight Mn to the weight average molecular weight Mw of the block copolymer (P), is 2.0 or less.

[0030]

[11] An abrasive composition for use in the planarization of at least one of an insulating layer and a wiring layer, comprising the dispersant described in any one of [1] to

[10] above, and cerium oxide.

[0031] Invention Effects

[0032] According to the dispersant of the present invention, the block copolymer (P) exhibits high dispersion stability of abrasive grains and can suppress abrasive grain aggregation caused by shear force. Furthermore, this suppression effect on abrasive grain aggregation is also fully realized when cerium oxide is used as the abrasive grain. Therefore, in semiconductor manufacturing processes, by using it as a dispersant in a chemical mechanical polishing abrasive composition for planarizing the surface of insulating layers or wiring layers, semiconductor devices with excellent surface planarity can be obtained. Detailed Implementation

[0033] The present invention will now be described in detail. It should be noted that in this specification, "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid, and "(meth)acrylate" refers to acrylate and / or methacrylate. Furthermore, "(meth)acryloyl" refers to acryloyl and / or methacryloyl.

[0034] The dispersant of the present invention is a chemical mechanical polishing dispersant used in semiconductor manufacturing processes to planarize the surface of at least one of an insulating layer and a wiring layer formed on a wafer (e.g., a silicon wafer). Furthermore, the polishing composition of the present invention contains cerium oxide (cerium dioxide) as abrasive particles and the dispersant of the present invention. Hereinafter, the dispersant and polishing composition of the present invention will be described.

[0035] [First Implementation]

[0036] Dispersants

[0037] The dispersant in the first embodiment of the present invention contains a block copolymer (P) as a water-soluble polymer, the block copolymer (P) comprising polymer block A and polymer block B, the polymer block A having a structural unit UA derived from at least one selected from vinyl monomers containing amide groups and vinyl monomers containing ester groups, and the polymer block B having a structural unit UB having an ionic functional group.

[0038] <Block copolymer (P)>

[0039] • Polymer block A

[0040] Polymer block A has a backbone containing carbon-carbon bonds derived from vinyl monomers. Polymer block A with a backbone containing carbon-carbon bonds has high adsorption capacity for abrasive particles. In addition, it moderately adsorbs onto abrasive objects with hydrophobic surfaces, imparting good wettability to the abrasive surface.

[0041] The vinyl monomers containing amide groups and vinyl monomers containing ester groups constituting the structural unit UA are not particularly limited. Examples of vinyl monomers containing amide groups include (meth)acrylamide; N-methyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-ethyl-N-methyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-(n-propyl)(meth)acrylamide, N-(tert-butyl)(meth)acrylamide, N-isopropyl(meth)acrylamide, N-(n-butyl)(meth)acrylamide, and N-(2-ethylhexyl)(meth)acrylamide, etc. (di)alkyl(meth)acrylamides; N-[3-(dimethylamino)propyl](meth)acrylamide, N-[3-( (Di)alkylaminoalkylamides such as [methylamino)propyl](methyl)acrylamide, N-[3-(ethylamino)propyl](methyl)acrylamide, and N-[3-(diethylamino)propyl](methyl)acrylamide; heterocyclic (methyl)acrylamides such as 4-(methyl)acryloylmorpholine; sulfonic acid (methyl)acrylamides such as 2-(methyl)acrylamide-2-methylpropanesulfonic acid or its salts; hydroxyl (methyl)acrylamides such as 2-hydroxyethylacrylamide; and N-vinyl amides such as N-vinylacetamide, N-vinylformamide, N-vinylisobutylamide, N-vinyl-2-pyrrolidone, and N-vinyl-ε-caprolactam.

[0042] Specific examples of vinyl monomers containing ester groups include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, ethylhexyl methacrylate, and n-decyl methacrylate.

[0043] Cyclohexyl methacrylate, methyl cyclohexyl methacrylate, tert-butyl cyclohexyl methacrylate, cyclododecyl methacrylate, isobornyl methacrylate, adamantyl methacrylate, dicyclopentenyl methacrylate and dicyclopentyl methacrylate are aliphatic cyclic esters of methacrylic acid.

[0044] Aromatic esters of (meth)acrylic acid, such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, and 3-phenoxypropyl (meth)acrylate;

[0045] (Meth)acrylate 2-methoxyethyl ester, (Meth)acrylate 3-methoxypropyl ester, (Meth)acrylate 4-methoxybutyl ester, (Meth)acrylate 2-ethoxyethyl ester, and other (Meth)acrylate alkoxyalkyl esters;

[0046] Hydroxyalkyl esters of methacrylates, such as 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate; (di)alkylaminoalkyl esters of methacrylates, such as N-[2-(methylamino)ethyl] methacrylate, N-[2-(dimethylamino)ethyl] methacrylate, N-[2-(ethylamino)ethyl] methacrylate, and N-[2-(diethylamino)ethyl] methacrylate;

[0047] Glycidyl methacrylate, 4-hydroxybutyl methacrylate glycidyl ether, and 3,4-epoxycyclohexyl methacrylate are epoxy-containing methacrylates; polyoxyethylene methacrylate, polyoxypropylene methacrylate and other polyoxyalkylene methacrylates are also included.

[0048] Polymer block A preferably has at least one structural unit derived from an amide-containing vinyl monomer as structural unit UA. Polymer block A having structural units derived from an amide-containing monomer imparts good dispersion stability to abrasive particles (especially cerium oxide), and is preferred in terms of improving the suppression of abrasive particle aggregation caused by shear forces. The structural unit UA preferably comprises a structural unit derived from an amide-containing vinyl monomer as shown in formula (1) below.

[0049] CH2=CR 1 -C(=O)-NR 2 -R 3 …(1)

[0050] (In equation (1), R) 1 R is a hydrogen atom or a methyl group; 2 and R 3 Each is independently a hydrogen atom, or a substituted or unsubstituted monovalent hydrocarbon group, or R 2 With R 3 For mutual bonding with R 2 and R 3 The bonded nitrogen atoms together form a ring group.

[0051] In the vinyl monomer shown in formula (1) above, R 2 and R 3 When at least one of the groups is a substituted monovalent hydrocarbon group, examples of such substituted monovalent hydrocarbon groups include groups having a secondary amino group, groups having a tertiary amino group, and hydroxyalkyl groups. Examples of vinyl monomers represented by formula (1) above include (meth)acrylamide, (di)alkyl(meth)acrylamides, (di)alkylaminoalkylamides, heterocyclic (meth)acrylamides, sulfonic acid (meth)acrylamides, and hydroxyl (meth)acrylamides. Among these, at least one selected from (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-ethyl-N-methyl(meth)acrylamide, 4-(meth)acryloylmorpholine, 2-hydroxyethylacrylamide, and 2-(meth)acrylamide-2-methylpropanesulfonic acid or salts thereof is preferred.

[0052] The structural unit UA of polymer block A is preferably derived from a water-soluble monomer. Specifically, the vinyl monomer containing an amide group is preferably selected from at least one of the vinyl monomers shown in formula (1) above, and N-vinyl-2-pyrrolidone. Among the vinyl monomers containing an ester group above, it is preferably selected from at least one of methyl acrylate, hydroxyalkyl acrylates of (meth)acrylates in which the alkyl group of the alkyl part has 1 to 4 carbon atoms, and polyoxyalkylene (meth)acrylates. It should be noted that in this specification, "water-soluble monomer" refers to a compound with a solubility of 2 g or more in 100 g of water at 20°C.

[0053] The polymer block A can be a block consisting only of structural unit UA, and may further have structural units derived from monomers different from amide-containing vinyl monomers and ester-containing vinyl monomers (hereinafter also referred to as "other monomers M1"), without impairing the function of the block copolymer (P).

[0054] Other monomers M1 are not particularly limited as long as they can copolymerize with vinyl monomers containing amide groups and vinyl monomers containing ester groups. Examples of other monomers M1 include alkyl vinyl ethers, vinyl alcohols, aromatic vinyl compounds, vinyl ester compounds, α-olefins, unsaturated acids, and unsaturated acid anhydrides.

[0055] Specific examples of other monomers M1 include, as alkyl vinyl ethers, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, n-hexyl vinyl ether, 2-ethylhexyl vinyl ether, n-octyl vinyl ether, n-nonyl vinyl ether, and n-decyl vinyl ether; as vinyl alcohols, vinyl alcohol, 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether; as aromatic vinyl compounds, styrene, vinyltoluene, and vinylxylene; as vinyl esters, vinyl formate, vinyl acetate, vinyl propionate, and vinyl benzoate; as α-olefins, ethylene, propylene, and butene; as unsaturated acids, (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, and fumaric acid; and as unsaturated anhydrides, maleic anhydride. As other monomers M1, one of these can be used alone or in combination of two or more.

[0056] For polymer block A, the content of structural unit UA relative to the total constituent monomer units of polymer block A is preferably 70% by mass or more. If the content of structural unit UA is 70% by mass or more, it is preferable in terms of producing polymer block A with excellent adsorption properties that can form abrasive particles. From this viewpoint, the content of structural unit UA relative to the total constituent monomer units of polymer block A is more preferably 80% by mass or more, further preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 99% by mass or more.

[0057] The content of structural units derived from amide-containing vinyl monomers in polymer block A is preferably the same as, or more than, the content of structural units derived from amide-containing vinyl monomers in polymer block B, and more preferably more than, the content of structural units derived from amide-containing vinyl monomers in polymer block A. Specifically, the content of structural units derived from amide-containing vinyl monomers in polymer block A relative to the total constituent monomer units of polymer block A is preferably 10% by mass or more, more preferably 30% by mass or more, further preferably 50% by mass or more, even more preferably 70% by mass or more, and particularly preferably 90% by mass or more.

[0058] The number-average molecular weight (Mn) of polymer block A is preferably in the range of 1,000 or more and 200,000 or less. If Mn is 1,000 or more, it is preferable in terms of fully demonstrating the improved adsorption capacity of the abrasive particles due to the introduction of polymer block A. Furthermore, if Mn is 200,000 or less, it is preferable in terms of sufficiently suppressing the formation of abrasive particle aggregation structures by adsorption of one polymer molecule onto the surfaces of multiple abrasive particles. The Mn of polymer block A is more preferably 1,500 or more, and even more preferably 2,000 or more. Furthermore, the Mn of polymer block A is more preferably 150,000 or less, even more preferably 100,000 or less, and particularly preferably 70,000 or less. It should be noted that in this specification, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polymer are values ​​converted from sodium polyacrylate determined by gel permeation chromatography (GPC). Specifically, these are values ​​determined by the method described in the examples described later.

[0059] • Polymer block B

[0060] The ionic functional groups of the structural unit UB are preferably carboxyl, sulfonic acid, phosphate, phosphonic acid, amino, or salts thereof, which exhibit moderate adsorption to abrasive particles (especially cerium oxide) and impart good dispersion stability to the abrasive particles. Among these, the ionic functional groups are preferably anionic functional groups such as carboxyl, sulfonic acid, phosphate, phosphonic acid, or their salts, and particularly preferably carboxyl, sulfonic acid, or salts of carboxyl or sulfonic acid groups.

[0061] The structural unit UB is preferably introduced into the block copolymer (P) by polymerizing a monomer having ionic functional groups (hereinafter also referred to as "monomers containing ionic groups"). The monomer containing ionic groups is not particularly limited as long as it is a monomer that can copolymerize with the constituent monomers of the polymer block A. Vinyl monomers are preferred in terms of good adsorption to abrasive particles and abrasive objects with hydrophobic surfaces, and in terms of high freedom of monomer selection.

[0062] Specific examples of monomers containing ionic groups include, for example, (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monobutyl itaconic acid, monobutyl maleate, cyclohexenedicarboxylic acid, or their salts, as vinyl monomers having a carboxyl group; for example, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, or their salts, as vinyl monomers having a phosphate group or a phosphonic acid group; for example, allylphosphonic acid, vinylphosphonic acid, methacrylate phosphorothoxyethyl ester, and methacrylate phosphorothoxypropyl ester. Esters, 3-chloro-2-acid phosphoryloxypropyl methacrylate, or their salts, etc.; as vinyl monomers having an amino group, examples include N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, N,N-dimethylaminopropyl methacrylate, N,N-dimethylaminopropyl (meth)acrylamide, or their salts, etc.; as vinyl monomers having a quaternary ammonium salt, examples include trimethyl-2-(meth)acryloyloxyethyl ammonium chloride, N-(2-(meth)acryloyloxyethyl)-N-benzyl-N,N-dimethyl ammonium chloride, (3-(meth)acrylamidopropyl)trimethyl ammonium chloride, etc.

[0063] As counterions for salts with ionic functional groups, examples of counterions for cationic functional groups include chloride ions, bromide ions, and iodide ions; examples of counterions for anionic functional groups include sodium ions, magnesium ions, and calcium ions. As monomers containing ionic groups, one of these can be used alone, or two or more can be used in combination.

[0064] The polymer block B can be a block consisting only of structural unit UB, and may further have structural units derived from monomers different from the monomers containing ionic groups (hereinafter also referred to as "other monomers M2"), without impairing the function of the block copolymer (P).

[0065] Other monomers M2 are not particularly limited as long as they can copolymerize with monomers containing ionic groups. Examples include vinyl monomers containing amide groups and vinyl monomers containing ester groups used in the manufacture of polymer block A, as well as vinyl monomers of other monomers M1 that do not have ionic functional groups. As other monomers M2, one of these can be used alone or in combination of two or more.

[0066] The polymer block B, together with the structural unit UB, may also contain a structural unit (hereinafter also referred to as "structural unit UC") having an alkyl group having 1 to 10 carbon atoms in its side chain portion. The presence of the structural unit UC in the polymer block B is advantageous in terms of improved hydrophobicity and enhanced adsorption to abrasive particles (especially cerium oxide). From the viewpoint of further improving the dispersion stability of the abrasive particles, the alkyl group having 2 or more carbon atoms in the side chain portion of the structural unit UC is preferably selected. Regarding the upper limit of the number of carbon atoms in the alkyl group having 8 or fewer carbon atoms, more preferably 7 or fewer carbon atoms, from the viewpoint of obtaining a polymer with high solubility in water systems, this alkyl group is preferably bonded to the main chain via a linking group (-COO-, -CONH-, etc.).

[0067] The monomer constituting the structural unit UC is preferably selected from at least one type of vinyl monomer containing an ester group and vinyl monomer containing an amide group. Among these, in terms of improving the dispersion stability of abrasive particles, it is preferably selected from at least one type of alkyl methacrylate with 1 to 10 carbon atoms in the alkyl ester moiety and N-alkyl (meth)acrylamide with 1 to 10 carbon atoms in the N-alkyl moiety, more preferably from at least one type of alkyl (meth)acrylate with 2 to 10 carbon atoms in the alkyl ester moiety and N-alkyl (meth)acrylamide with 2 to 10 carbon atoms in the N-alkyl moiety. It should be noted that the polymer block B may have only one type of structural unit UC or more than two types.

[0068] In polymer block B, the content of the structural unit UB relative to the total constituent monomer units of polymer block B is preferably 40% by mass or more. If the content of the structural unit UB is 40% by mass or more, it is preferable in terms of producing polymer block B with excellent dispersion stability for abrasive particles. From this viewpoint, the content of the structural unit UB relative to the total constituent monomer units of polymer block B is more preferably 50% by mass or more, further preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more. Regarding the upper limit of the content of the structural unit UB, when introducing structural units derived from other monomers, it is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less relative to the total constituent monomer units of polymer block B.

[0069] From the viewpoint of improving the adsorption of abrasive particles and fully achieving the effect of improving the dispersion stability of abrasive particles, the content of the structural unit UC is preferably 1% by mass or more, more preferably 2% by mass or more, further preferably 5% by mass or more, and particularly preferably 10% by mass or more, relative to the total constituent monomer units of polymer block B. Regarding the upper limit of the content of the structural unit UC, relative to the total constituent monomer units of polymer block B, it is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 25% by mass or less.

[0070] In the block copolymer (P), at least polymer block B is a copolymer with ionic functional groups, and polymer block A may also have ionic functional groups. When polymer block A has ionic functional groups, polymer block A and polymer block B preferably satisfy at least one of conditions I and II below.

[0071] Condition I: The ionic functional groups of polymer block A are different from those of polymer block B.

[0072] Condition II: The content of ionic functional groups in polymer block A is less than the content of ionic functional groups in polymer block B.

[0073] When polymer block A has an ionic functional group, from the viewpoint of exhibiting moderate adsorption to abrasive particles (especially cerium oxide) and imparting good dispersion stability to the abrasive particles, the ionic functional group is preferably a sulfonic acid group or a carboxyl group, more preferably a sulfonic acid group. Regarding condition I above, the combination of the ionic functional groups of polymer block A and polymer block B is not particularly limited. It should be noted that when at least one of polymer block A and polymer block B has multiple ionic functional groups, each polymer block only needs to have at least one different ionic functional group. As a preferred example of a combination satisfying condition I, examples include polymer block A having a sulfonic acid group as the ionic functional group and polymer block B having a carboxyl group as the ionic functional group.

[0074] When only condition I is met, the content of the structural unit with ionic functional group in polymer block A is preferably 1,000 parts by mass or less, more preferably 800 parts by mass or less, relative to 100 parts by mass of the structural unit UB with ionic functional group in polymer block B.

[0075] Regarding condition II above, the preferred range of the content of structural units with ionic functional groups in polymer block A varies depending on whether condition I is satisfied. When condition I is satisfied, the content of structural units with ionic functional groups in polymer block A, relative to 100 parts by mass of structural units UB with ionic functional groups in polymer block B, is preferably 90 parts by mass or less, more preferably 80 parts by mass or less. When condition I is not satisfied, the content of structural units with ionic functional groups in polymer block A, relative to 100 parts by mass of structural units UB with ionic functional groups in polymer block B, is preferably 75 parts by mass or less, more preferably 50 parts by mass or less, further preferably 30 parts by mass or less, and even more preferably 10 parts by mass or less.

[0076] When polymer block A does not actually have structural units derived from ionic functional groups, the difference in adsorption of abrasive particles and the object being ground within one polymer molecule increases, which can further suppress the formation of agglomerated structures of abrasive particles caused by shear force, and is therefore preferred.

[0077] Furthermore, for the block copolymer (P), at least polymer block A has structural unit UA, preferably a structural unit derived from an amide-containing vinyl monomer. On the other hand, polymer block B may or may not have a structural unit derived from an amide-containing vinyl monomer. When polymer block B has a structural unit derived from an amide-containing vinyl monomer, polymer blocks A and B preferably satisfy condition II above in order to further reduce the formation of agglomerated structures of abrasive particles due to shear force, and it is particularly preferred that polymer block A substantially does not have ionic functional groups. It should be noted that "substantially does not have ionic functional groups" in this specification means that compounds with ionic functional groups are not used as monomer raw materials.

[0078] For polymer block B, the number-average molecular weight (Mn) converted from sodium polyacrylate by GPC is preferably in the range of 1,000 or more and 200,000 or less. If Mn is 1,000 or more, it is preferable to fully demonstrate the improved adsorption effect on abrasive particles caused by the intramolecular introduction of polymer block B. Furthermore, if Mn is 200,000 or less, the resulting block copolymer (P) is preferable in that it can suppress the aggregation of abrasive particles due to shear force and can sufficiently ensure the dispersion stability of the abrasive particles. For polymer block A, Mn is more preferably 1,500 or more, further preferably 2,000 or more, and particularly preferably 2,500 or more. The upper limit of Mn for polymer block A is more preferably 150,000 or less, further preferably 100,000 or less, and particularly preferably 70,000 or less.

[0079] <Preparation of Block Copolymer (P)>

[0080] Block copolymers (P) are not particularly limited in their manufacturing method as long as they have two or more different chain segments; they can be manufactured using known methods. Specific examples of methods for manufacturing block copolymers (P) include various controlled polymerization methods such as living radical polymerization and living anionic polymerization; and methods of coupling polymers with functional groups together. Among these, living radical polymerization is preferred due to its high controllability of molecular weight dispersion (PDI), excellent dispersion stability for producing abrasive particles, ease of operation, and applicability to a wide range of monomers. When using living radical polymerization, the polymerization form is not particularly limited; it can be carried out through various methods such as bulk polymerization, solution polymerization, emulsion polymerization, microemulsion polymerization, and suspension polymerization.

[0081] For example, in the case of producing block copolymers (P) by solution polymerization using living radical polymerization, an organic solvent and monomer are introduced into a reactor, a radical polymerization initiator is added, and polymerization is preferably carried out by heating, thereby obtaining the target block copolymer (P). The polymerization can be carried out using any of the following processes: batch process, semi-batch process, dry continuous polymerization process, continuous stirred tank process (CSTR), etc.

[0082] In the manufacture of block copolymers (P), known polymerization methods can be used as living radical polymerization. Specific examples of the living radical polymerization methods used include living radical polymerization with an exchange chain mechanism, living radical polymerization with a binding-dissociation mechanism, and living radical polymerization with an atom transfer mechanism. Specific examples of living radical polymerization with an exchange chain mechanism include reversible addition-fragmentation chain transfer polymerization (RAFT), iodine transfer polymerization, polymerization using organotellurium compounds (TERP), polymerization using organoantimony compounds (SBRP), and polymerization using organobismuth compounds (BIRP).

[0083] Examples of living radical polymerization with a binding-dissociation mechanism include the nitryl radical polymerization (NMP process); examples of atom transfer polymerization (ATRP process) include the atom transfer mechanism. Among these, living radical polymerization with an exchange chain mechanism or a binding-dissociation mechanism is preferred in terms of its applicability to the widest range of vinyl monomers and its excellent controllability of polymerization. In terms of avoiding contamination of the workpiece due to the introduction of metal or half-metal compounds, the RAFT process or the NMP process is preferred. From the viewpoint of ease of implementation, the RAFT process is particularly preferred.

[0084] In the RAFT process, polymerization occurs via a reversible chain transfer reaction in the presence of a polymerization control agent (RAFT agent) and a free radical polymerization initiator. Various known RAFT agents, such as dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds, can be used as RAFT agents. Among these, trithiocarbonate compounds and dithiocarbamate compounds are preferred for obtaining polymers with smaller molecular weight dispersions. Furthermore, monofunctional compounds with only one active site or polyfunctional compounds with two or more active sites can be used as RAFT agents. By using these compounds, polymers with narrower molecular weight dispersions can be obtained. The amount of RAFT agent used is appropriately adjusted based on the monomer and the type of RAFT agent used.

[0085] As polymerization initiators used in RAFT polymerization, known free radical polymerization initiators such as azo compounds, organic peroxides, and persulfates can be used. Among these, azo compounds are preferred because they are easy to handle in terms of safety and are less likely to cause side reactions during free radical polymerization. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylpentanitrile), 4,4'-azobis(4-cyanopentanoic acid), 2,2'-azobis(4-methoxy-2,4-dimethylpentanitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carboxylonitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], and 2,2'-azobis(N-butyl-2-methylpropionamide). As a free radical polymerization initiator, one type can be used alone, or two or more types can be used in combination.

[0086] There is no particular limitation on the amount of free radical polymerization initiator used. From the viewpoint of obtaining polymers with smaller molecular weight dispersion, it is preferable to use 0.5 moles or less, and more preferably 0.2 moles or less, relative to 1 mole of RAFT agent. Furthermore, from the viewpoint of ensuring stable polymerization, the lower limit of the amount of free radical polymerization initiator used is preferably 0.01 moles or more, and more preferably 0.05 moles or more, relative to 1 mole of RAFT agent. The amount of free radical polymerization initiator used relative to 1 mole of RAFT agent is preferably 0.01 to 0.5 moles, and more preferably 0.05 to 0.2 moles.

[0087] In the use of solvents in living radical polymerization, examples of polymerization solvents include aromatic compounds such as benzene, toluene, xylene, and anisole; ester compounds such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; ketone compounds such as acetone and methyl ethyl ketone; dimethylformamide, acetonitrile, dimethyl sulfoxide, alcohols, and water. One of these solvents can be used alone, or two or more can be used in combination.

[0088] In polymerization reactions using the RAFT method, the reaction temperature is preferably 40°C or higher and 100°C or lower, more preferably 45°C or higher and 90°C or lower, and even more preferably 50°C or higher and 80°C or lower. A reaction temperature of 40°C or higher is preferred for smooth polymerization, while a reaction temperature of 100°C or lower is preferred for suppressing side reactions and mitigating limitations related to the initiators and solvents that can be used. Furthermore, the reaction time can be appropriately set depending on the monomers used, preferably 1 hour or higher and 48 hours or lower, more preferably 3 hours or higher and 24 hours or lower. Polymerization can be carried out in the presence of a chain transfer agent (e.g., alkyl thiols with 2 to 20 carbon atoms, etc.). In cases where there are concerns about metal contamination due to reactor corrosion during manufacturing processes, particularly when using monomers with acidic groups, it is preferable to use equipment with a surface coated with a fluoropolymer resin, etc. In addition, in this case, containers for storing the product, etc., are preferably made of corrosion-resistant resin. When using a resin container, the container is preferably made of a material that inhibits the mixing of metals due to the dissolution of fillers, etc.

[0089] For the block copolymer (P), the number-average molecular weight (Mn) converted from sodium polyacrylate as determined by GPC is preferably in the range of 2,000 or more and 300,000 or less. If Mn is 2,000 or more, it is preferable in that it can sufficiently ensure the wettability of the surface of the object being ground while suppressing the decrease in grinding rate. Furthermore, if Mn is 300,000 or less, it is preferable in that it can sufficiently suppress the agglomeration of abrasive grains due to shear force and sufficiently suppress the generation of defects such as scratches during grinding. From this viewpoint, the Mn of the block copolymer (P) is more preferably 2,500 or more, further preferably 3,000 or more, and even more preferably 3,500 or more. Regarding the upper limit of the Mn of the block copolymer (P), it is more preferably 200,000 or less, further preferably 150,000 or less, even more preferably 110,000 or less, and particularly preferably 100,000 or less.

[0090] The weight-average molecular weight (Mw) of the block copolymer (P), converted from sodium polyacrylate as determined by GPC, is preferably in the range of 3,000 or more and 400,000 or less. The Mw of the block copolymer (P) is more preferably 4,000 or more, and even more preferably 5,000 or more. Regarding the upper limit of the Mw of the block copolymer (P), it is more preferably 300,000 or less, even more preferably 220,000 or less, even more preferably 150,000 or less, and particularly preferably 100,000 or less.

[0091] The molecular weight dispersibility (PDI = (Mw / Mn)) expressed as the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn of the block copolymer (P) is preferably 2.5 or less. For polymers exhibiting abrasive dispersion function, molecular weight is considered to influence the adsorption-desorption rate on the abrasive material; generally, the smaller the molecular weight of the polymer, the higher the adsorption-desorption rate on the abrasive material. Furthermore, polymers with large molecular weights are considered to be more prone to forming agglomerated abrasive structures due to shear forces. Therefore, polymers used in abrasive dispersant applications preferably have a narrow molecular weight distribution. From this perspective, the PDI of the block copolymer (P) is more preferably 2.0 or less, further preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.3 or less. The lower limit of PDI is typically 1.0.

[0092] From the viewpoint of suppressing the formation of agglomerated structures of abrasive particles due to shear force, the mass ratio A / B of polymer block A to polymer block B in the 1-molecule block copolymer (P) is preferably set to 5 / 95 to 95 / 5. A / B ratio is more preferably 10 / 90 to 90 / 10, further preferably 15 / 85 to 85 / 15, even more preferably 20 / 80 to 80 / 20, and particularly preferably 25 / 75 to 75 / 25. It should be noted that the ratio A / B can be appropriately selected by adjusting the ratio of the monomers used in the manufacture of polymer block A and the monomers used in the manufacture of polymer block B.

[0093] Block copolymers (P) are not particularly limited in number or arrangement order of polymer blocks A and B per molecule, as long as they contain polymer blocks A and B. Specific examples of block copolymers (P) include, for instance, a (AB) diblock copolymer containing polymer blocks A and B, a (ABA) triblock copolymer containing polymer blocks A / B / A, and a (BAB) triblock copolymer containing polymer blocks B / A / B. Furthermore, block copolymers (P) can also be multiblock copolymers having four or more polymer blocks, and may further contain polymer blocks other than polymer blocks A and B. Among these, block copolymers (P) with sufficiently high dispersion stability for efficiently producing abrasive particles (especially cerium oxide) are preferred, especially diblock copolymers with an AB-type structure.

[0094] The dispersant of the present invention only needs to contain a block copolymer (P). Therefore, the dispersant can be in the form of a single component containing only the block copolymer (P), or it can be in the form of containing components different from the block copolymer (P) (hereinafter also referred to as "other components") together with the block copolymer (P).

[0095] The dispersant of the present invention may include a solvent as another component. Examples of solvents include water, organic solvents, and mixtures of water and organic solvents. Among these, the solvent contained in the dispersant is preferably a solvent capable of dissolving the block copolymer (P) as a water-soluble polymer, more preferably water, or a mixture of water and an organic solvent capable of dissolving in water, and particularly preferably water. Examples of organic solvents used with water include alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone and methyl ethyl ketone; alkylene glycols such as ethylene glycol and propylene glycol; ethers such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, and tetrahydrofuran; esters such as ethylene glycol monomethyl ether acetate and ethyl acetate; and amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide. One organic solvent may be used alone, or two or more may be used in combination.

[0096] When the dispersant contains a block copolymer (P) and a solvent, from the viewpoint of ensuring sufficient contact between the surface of the workpiece and the abrasive pad and the block copolymer (P), the content of the block copolymer (P) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total mass of the block copolymer (P) and the solvent. Furthermore, regarding the upper limit of the block copolymer (P) content, from the viewpoint of suppressing reduced processability due to excessively high viscosity, it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, relative to the total mass of the block copolymer (P) and the solvent.

[0097] Abrasive Compositions

[0098] The abrasive composition of the present invention contains cerium oxide (cerium dioxide) as abrasive particles and the above-mentioned dispersant. Cerium oxide can grind the surface at a higher grinding speed than silicon dioxide, alumina, etc., and has the advantage of lower hardness than alumina, etc., which can suppress the generation of defects on the ground surface.

[0099] Cerium oxide is used in particulate form. The average particle size of cerium oxide is not particularly limited, but is generally from 1 nm to 500 nm. From the viewpoint of ensuring high grinding speed, this average particle size is preferably 2 nm or more, more preferably 3 nm or more. Regarding the upper limit of the average particle size, from the viewpoint of suppressing the formation of scratches on the surface of the object being ground, it is preferably 300 nm or less, more preferably 100 nm or less. It should be noted that in this specification, the average particle size of cerium oxide is calculated using the specific surface area (m²) obtained by the BET (nitrogen adsorption) method. 2 The primary particle size is calculated using the ratio of g / g.

[0100] From the viewpoint of achieving high grinding speed, the cerium oxide content in the abrasive composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Regarding the upper limit of the cerium oxide content, from the viewpoint of ensuring good smoothness of the object being ground, it is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less.

[0101] The content of the dispersant is preferably set to a concentration of the solid component of the block copolymer (P) relative to the total amount of the abrasive composition of 0.001% by mass or more, and more preferably to a concentration of 1% by mass or more. Regarding the upper limit of the dispersant content, it is preferably set to a concentration of the solid component of the block copolymer (P) relative to the total amount of the abrasive composition of 10% by mass or less, and more preferably to a concentration of 5% by mass or less.

[0102] The abrasive composition may contain a solvent. The solvent is preferably an aqueous solvent, such as water or a mixture of water and a solvent. The solvent is preferably a water-compatible solvent, such as an alcohol like ethanol. Furthermore, the abrasive composition may contain known additives, such as abrasion accelerators, pH adjusters, surfactants, chelating agents, and corrosion inhibitors, to the extent that it does not impair the effects of the invention.

[0103] The abrasive composition is typically prepared as a slurry mixture by mixing the components using known methods. The viscosity of the abrasive composition at 25°C can be appropriately selected according to the object being abraded, the shear rate during abrasion, etc., preferably in the range of 0.1 to 10 mPa·s, more preferably in the range of 0.5 to 5 mPa·s.

[0104] The abrasive composition of the present invention contains a block copolymer (P) as a dispersant, thus exhibiting high dispersion stability of abrasive particles (especially cerium oxide particles) and a high effect in suppressing abrasive particle aggregation caused by shear force. Therefore, the abrasive composition of the present invention is suitable for use as an abrasive fluid in the manufacturing process of semiconductor devices for planarizing the surface of at least one of insulating films and metal wirings, specifically for example, planarizing oxide films (such as silicon oxide films) during shallow trench isolation (STI) fabrication, planarizing the surface of metal wirings including copper, copper alloys, aluminum alloys, etc., and planarizing the surface of interlayer insulating films (oxide films), thereby reducing the generation of defects and obtaining insulating films and metal wirings with excellent surface smoothness.

[0105] Example 1

[0106] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. It should be noted that, unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass," respectively. The method for determining the molecular weight of the polymer is as described below.

[0107] <Molecular weight determination>

[0108] The obtained polymer was subjected to gel permeation chromatography (GPC) under the following conditions to determine the number-average molecular weight (Mn) and weight-average molecular weight (Mw) converted using sodium polyacrylate. Furthermore, the molecular weight dispersion (PDI = Mw / Mn) was calculated from the obtained Mn and Mw values.

[0109] ○ Measurement conditions

[0110] Device name: Tosoh Corporation HLC-8420GPC

[0111] Column: Tosoh TSK-GEL400PWXL (estimated resistance limit 1 million)

[0112] Sodium polyacrylate standard material molecular weight:

[0113] (Mp: peak molecular weight, Mn: number-average molecular weight, Mw: weight-average molecular weight)

[0114] Sample 1: Mp = 1250, Mn = 1230, Mw = 1930

[0115] Sample 2: Mp = 2925, Mn = 2280, Mw = 3800

[0116] Sample 3: Mp = 7500, Mn = 6200, Mw = 8300

[0117] Sample 4: Mp = 16000, Mn = 12800, Mw = 18100

[0118] Sample 5: Mp = 28000, Mn = 23100, Mw = 37100

[0119] Sample 6: Mp = 62900, Mn = 47900, Mw = 83400

[0120] Sample 7: Mp = 130500, Mn = 97800, Mw = 165300

[0121] Sample 8: Mp = 392600, Mn = 311300, Mw = 495000

[0122] Standard curve: Prepared using the molecular weight Mp of the above-mentioned sodium polyacrylate standard material in cubic form.

[0123] Solvent: 0.1M NaNO3 aqueous solution

[0124] Temperature: 40℃

[0125] Detector: RI

[0126] Flow rate: 1.0 mL / min

[0127] Sample concentration: 0.5 g / L

[0128] 1. Polymer Synthesis

[0129] [Synthesis Example 1A]

[0130] In a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, 200g of pure water, 50.8g of acrylic acid (hereinafter referred to as "AA"), 0.035g of 4,4'-azobis(4-cyanopentanoic acid) (hereinafter referred to as "ACVA") as an initiator, and 1.29g of 3-((((1-carboxyethyl)thio)thio)propionic acid (manufactured by BORONMOLECULAR, hereinafter referred to as "BM1429") as a RAFT agent were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was cooled with water, and the reaction was stopped. Next, 180g of pure water, 50.8g of acrylamide (hereinafter referred to as "AAm"), and 0.045g of ACVA were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was cooled with water, and the reaction was stopped. The polymerization rates of AA and AAm, determined by gas chromatography (GC), were 97% and 95%, respectively. The molecular weights of the resulting water-soluble block copolymer (denoted as "polymer A1") were determined by GPC, with Mn of 22,700, Mw of 27,200, and PDI of 1.2.

[0131] [Synthetic Examples 2A-4A, 6A-10A]

[0132] The raw materials were changed as shown in Table 1, and the same procedures as in Synthesis Example 1A were performed to obtain water-soluble block copolymers (polymers B1-D1, F1-J1). The molecular weights of each polymer determined by GPC are shown in Table 2.

[0133] [Synthesis Example 5A]

[0134] Methanol (240 g), AA (63.0 g), N-tert-butylacrylamide (hereinafter referred to as "TBAM") (12.6 g), 2,2'-azobis(2,4-dimethylpentanonitrile) (manufactured by Wako Pure Chemical Industries Co., Ltd., hereinafter referred to as "V-65") (0.450 g), and BM1429 (0.722 g) as initiators were added to a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55°C. After 6 hours, the mixture was cooled with water, and the reaction was stopped. The solvent was removed by evaporation, and the V-65 precipitated by the addition of pure water (400 g) and unreacted TBAM were recovered by filtration. Next, AAM (40.3 g) and ACVA (0.0475 g) were added, and the mixture was thoroughly degassed by bubbling with nitrogen. Polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was cooled with water, and the reaction was stopped. The polymerization rates of the monomers AA and TBAM, and AAM, determined by GC, were 95% and 89%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer E1") was determined by GPC, with Mn of 10900, Mw of 16400, and PDI of 1.5.

[0135] [Comparative Synthesis Example 1A]

[0136] In a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, 400g of pure water, 50.5g of AAM, 50.5g of 2-acrylamide-2-methylpropanesulfonic acid (hereinafter referred to as "ATBS"), 0.112g of ACVA, and 2.57g of BM1429 were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was water-cooled, and the reaction was stopped. The polymerization rates of AAM and ATBS were determined by GC and NMR, respectively, and the overall reaction rate was 89%. The molecular weight of the resulting random copolymer (denoted as "polymer K1") was determined by GPC: Mn = 6790, Mw = 11500, and PDI = 1.7.

[0137] [Compare Synthetic Examples 2A and 3A]

[0138] The raw materials were changed as shown in Table 1, and the same procedures as in Comparative Synthesis Example 1A were performed to obtain polymers L1 and M1. The molecular weights of each polymer were determined by GPC and are shown in Table 2.

[0139] [Comparative Synthesis Example 4A]

[0140] Methanol (330 g), TBAM (8.27 g), ATBS (74.4 g), V-65 (0.496 g), and BM1429 (1.75 g) were added to a 1 L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55 °C. After 6 hours, the mixture was water-cooled to stop the reaction. The polymerization rates of TBAM and ATBS, determined by GC and NMR respectively, showed a total reaction rate of 85%. The molecular weight of the resulting random copolymer (denoted as "polymer N1") was determined by GPC: Mn = 11900, Mw = 21400, and PDI = 1.8.

[0141] [Table 1]

[0142]

[0143] It should be noted that the abbreviations of the compounds in Table 1 are as follows.

[0144] AAm: Acrylamide

[0145] AA: Acrylic acid

[0146] ATBS: 2-Acrylamide-2-methylpropanesulfonic acid

[0147] ACMO: 4-Acryloylmorpholine

[0148] HEA: 2-Hydroxyethyl acrylate

[0149] MA: Methyl acrylate

[0150] TBAM: N-tert-butylacrylamide

[0151] ACVA: 4,4'-Azobis(4-cyanopentanoic acid)

[0152] V-65: 2,2'-Azobis(2,4-dimethylpentanonitrile)

[0153] MeOH: Methanol

[0154] BM1429: 3-((((1-Carboxyethyl)thio)thiocarbonyl))thio)propionic acid

[0155] 2. Measurement and Evaluation

[0156] [Example 1A]

[0157] As a dispersant, an aqueous polymer solution containing polymer A1 at a solids concentration of 20% was prepared. 4.0 g of cerium oxide nanoparticles (20 nm primary particle size) and 2 g of dispersant were added to a 50 mL glass pressure-resistant bottle and mixed thoroughly. The pH was adjusted to 7 using a 0.5 mol / L HCl solution or a 25% (w / w) NH3 aqueous solution. Subsequently, 20 g of 1 mm diameter zirconia beads were added, and the mixture was stirred for 30 minutes with a paint shaker. After filtering to remove the beads, the mixture was allowed to stand overnight to obtain a slurry-like abrasive composition. The resulting abrasive composition was used for the following determinations and evaluations. The results of the determinations and evaluations are shown in Table 2.

[0158] <Slurry viscosity>

[0159] The shear viscosity [mPa·s] of the prepared abrasive composition was determined under the following conditions.

[0160] ○ Measurement conditions

[0161] Device body: Physical MCR301 manufactured by Anton Paar

[0162] Measurement temperature: 25℃

[0163] Slip speed range: 1 [s] -1 ]~1000[s -1 ]

[0164] It can be said that the lower the viscosity of the slurry, the less likely the cerium oxide particles will aggregate due to shear force, resulting in excellent dispersion stability. It should be noted that for particles that have settled overnight, each container is redispersed by hand shaking, and the viscosity of the abrasive composition in this redispersed state is measured.

[0165] <Pulp Appearance>

[0166] The appearance of the prepared abrasive composition is visually confirmed to determine the appearance of the slurry. The determination is first performed as in Example 1A, except without the addition of a dispersant, to prepare a slurry-like abrasive composition as a reference sample. This reference sample is left to stand for 24 hours, and the settling thickness D is measured. This measured settling thickness D is recorded as 100%, and the degree of particle settling [%] of each abrasive composition is calculated. The determination criteria are as follows. It should be noted that for particles that settle overnight, each container is manually shaken to redisperse, and particle settling is confirmed within 1 hour after redispersing.

[0167] ◎: Particle settling within 1 hour is less than 5%.

[0168] ○: Particle settling within 1 hour is greater than 5% and less than 15%.

[0169] △: Particle settling within 1 hour is greater than 15% and less than 30%.

[0170] ×: Particle settling within 1 hour is greater than 30%.

[0171] [Examples 2A-10A, Comparative Examples 1A-4A]

[0172] The polymers used were changed as described in Table 2. Apart from this, the dispersants were prepared in the same manner as in Example 1A, and slurry-like abrasive compositions were prepared using the same procedures as in Example 1A. The resulting abrasive compositions were subjected to slurry viscosity determination and slurry appearance evaluation in the same manner as in Example 1A. The results are shown in Table 2.

[0173] [Table 2]

[0174]

[0175] It should be noted that in Table 2, the values ​​of monomer 1 and monomer 2 in the "Polymer Block A" and "Polymer Block B" columns represent the monomer composition (mass ratio) of each polymer calculated from the amount of monomer added during polymerization. The "A / B mass ratio" represents the ratio (mass ratio) of polymer block A to polymer block B in each polymer, calculated from the monomer composition of each polymer. The values ​​in the "Mn of Each Block" column are the design values ​​of Mn for each polymer block A and polymer block B. The Mn, Mw, and PDI in the "Polymer Molecular Weight Properties" column are measured values ​​determined using GPC.

[0176] Based on the results of Examples 1A to 10A, it is evident that by using a block copolymer (P) having polymer blocks A and B as a dispersant, sedimentation of cerium oxide particles is difficult to occur, resulting in a slurry with cerium oxide particles stably dispersed within the system. Furthermore, it is observed that the slurry containing the block copolymer (P) has a viscosity as low as 35 mPa·s or less, making agglomeration of cerium oxide particles due to shear force difficult to occur. In particular, in Example 5A, which uses polymer E1 with polymer blocks B having monomer units derived from TBAM, particle sedimentation is less likely to occur compared to Examples 9A and 10A, which use polymers I1 and J1, respectively, which do not have monomer units derived from TBAM, and the slurry viscosity also shows a lower value.

[0177] In contrast, in Comparative Examples 1A to 4A, which used random copolymers instead of block copolymers (P), the cerium oxide particles exhibited a greater degree of sedimentation. Furthermore, the slurry viscosity was high, exceeding 42 mPa·s, which is a result of the poor dispersion stability of the cerium oxide particles.

[0178] [Second Implementation]

[0179] Next, the dispersant and abrasive composition of the second embodiment will be described. It should be noted that, for the sake of brevity, the description of the first embodiment will be used for the parts that are the same as those in the first embodiment described above.

[0180] Dispersants

[0181] In the second embodiment of the present invention, the dispersant contains a block copolymer (P) as a water-soluble polymer. The block copolymer (P) has polymer blocks A and B. Polymer block A has a structural unit having ionic functional groups, and polymer block B is a segment with a monomer composition different from that of polymer block A and also has a structural unit having ionic functional groups. It should be noted that, hereinafter, the structural unit having ionic functional groups in polymer block A is also referred to as "structural unit UA-2," and the structural unit having ionic functional groups in polymer block B is also referred to as "structural unit UB-2."

[0182] <Block copolymer (P)>

[0183] • Polymer block A

[0184] The ionic functional groups of structural unit UA-2 exhibit moderate adsorption to abrasive particles (especially cerium oxide), and are preferably carboxyl, sulfonic acid, phosphate, phosphonic acid, amino, or salts thereof, in order to impart good dispersion stability to the abrasive particles. Among these, the ionic functional groups are preferably anionic functional groups such as carboxyl, sulfonic acid, phosphate, and phosphonic acid, or their salts, and are particularly preferably carboxyl, sulfonic acid, or their salts.

[0185] The structural unit UA-2 is preferably incorporated into the block copolymer (P) by polymerization using a monomer having ionic functional groups (hereinafter also referred to as "monomers containing ionic groups"). Monomers containing ionic groups are preferably vinyl monomers due to their good adsorption to abrasive particles and abrasive objects with hydrophobic surfaces, and the high degree of freedom in monomer selection. The block copolymer (P) has a backbone containing carbon-carbon bonds, thereby exhibiting high adsorption to abrasive particles. Furthermore, it can moderately adsorb onto abrasive objects with hydrophobic surfaces, imparting good wettability to the abrasive surface. From the viewpoint of obtaining a polymer with high solubility in water, monomers containing ionic groups are preferably water-soluble monomers. It should be noted that "water-soluble monomer" refers to a compound with a solubility of 2 g or more per 100 g of water at 20°C.

[0186] For specific examples of monomers containing ionic groups that can be used in the manufacture of the block copolymer (P) of this embodiment, and for the explanation of counterions in the case where the ionic functional group is a salt, the examples of monomers containing ionic groups and counterions described in the polymer block B of the block copolymer (P) of the first embodiment described above can be referenced.

[0187] The polymer block A can be a block consisting only of structural unit UA-2, and may further have structural units derived from monomers different from those containing ionic groups (hereinafter also referred to as "other monomers M1-2"), without impairing the function of the block copolymer (P).

[0188] Other monomers M1-2 are not particularly limited as long as they are monomers capable of copolymerizing with monomers containing ionic groups, but preferably at least one of vinyl monomers containing amide groups and vinyl monomers containing ester groups. Specific examples of vinyl monomers containing amide groups include, for example, (di)alkyl(meth)acrylamides, (di)alkylaminoalkylamides, heterocyclic (meth)acrylamides, hydroxyl-containing (meth)acrylamides, N-vinylamides, etc., which are exemplified as vinyl monomers containing amide groups as structural units UA of polymer block A in the first embodiment described above.

[0189] Specific examples of other monomers M1-2 being ester-containing vinyl monomers include, for example, ester-containing vinyl monomers such as (meth)acrylate alkyl esters, (meth)acrylate aliphatic cyclic esters, (meth)acrylate aromatic esters, (meth)acrylate alkoxyalkyl esters, (meth)acrylate (di)alkylaminoalkyl esters, epoxy-containing (meth)acrylates, and polyoxyalkylene (meth)acrylates, etc., which are used as other monomers M1-2. One of these monomers can be used alone, or two or more can be used in combination.

[0190] The polymer block A, together with the structural unit UA-2, may also contain a structural unit (structural unit UC) having an alkyl group having 1 to 10 carbon atoms in its side chain portion. The presence of the structural unit UC in the polymer block A is advantageous in terms of improved hydrophobicity and enhanced adsorption to abrasive particles (especially cerium oxide). From the viewpoint of further improving the dispersion stability of the abrasive particles, the alkyl group having 2 or more carbon atoms in the side chain portion of the structural unit UC is preferred. Regarding the upper limit of the number of carbon atoms in the alkyl group having 8 or fewer carbon atoms, more preferably 7 or fewer carbon atoms, from the viewpoint of obtaining a polymer with high solubility in water systems, this alkyl group is preferably bonded to the main chain via a linking group (-COO-, -CONH-, etc.).

[0191] The monomer constituting the structural unit UC is preferably selected from at least one type of vinyl monomer containing an ester group and vinyl monomer containing an amide group. Among these, in terms of improving the dispersion stability of abrasive particles, it is preferably selected from at least one type of alkyl methacrylate with 1 to 10 carbon atoms in the alkyl ester moiety and N-alkyl (meth)acrylamide with 1 to 10 carbon atoms in the N-alkyl moiety, more preferably from at least one type of alkyl (meth)acrylate with 2 to 10 carbon atoms in the alkyl ester moiety and N-alkyl (meth)acrylamide with 2 to 10 carbon atoms in the N-alkyl moiety. It should be noted that the polymer block A may have only one type of structural unit UC or may have two or more types.

[0192] In polymer block A, the content of structural unit UA-2 having ionic functional groups is preferably 30% by mass or more relative to the total constituent monomer units of polymer block A. If the content of structural unit UA-2 is 30% by mass or more, it is suitable for further improving the dispersion stability of the abrasive particles. From this viewpoint, the content of structural unit UA-2 relative to the total constituent monomer units of polymer block A is more preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more. Regarding the upper limit of the content of structural unit UA-2, when introducing structural units derived from other monomers, it is preferably 99% by mass or less, more preferably 98% by mass or less, and even more preferably 96% by mass or less relative to the total constituent monomer units of polymer block A.

[0193] From the viewpoint of improving the adsorption of abrasive particles and fully achieving the effect of improving the dispersion stability of abrasive particles, the content of the structural unit UC is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 4% by mass or more, relative to the total constituent monomer units of polymer block A. Regarding the upper limit of the content of the structural unit UC, relative to the total constituent monomer units of polymer block A, it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0194] The number-average molecular weight (Mn) of polymer block A is preferably in the range of 1,000 or more and 100,000 or less. If Mn is 1,000 or more, it is preferable in terms of fully demonstrating the improved dispersion stability of the abrasive particles due to the introduction of polymer block A. Furthermore, if Mn is 100,000 or less, it is preferable in terms of sufficiently suppressing the formation of abrasive particle aggregation structures by adsorption of one polymer molecule onto the surfaces of multiple abrasive particles. More preferably, the Mn of polymer block A is 1,500 or more, further preferably 2,000 or more, and even more preferably 3,000 or more. Furthermore, more preferably, the Mn of polymer block A is 70,000 or less, further preferably 50,000 or less, and particularly preferably 30,000 or less. It should be noted that the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polymer are values ​​converted from sodium polyacrylate measured by GPC. Specifically, these are values ​​measured by the method described in the examples described later.

[0195] • Polymer block B

[0196] Examples of ionic functional groups in structural unit UB-2 include those exemplified as ionic functional groups in structural unit UA-2. Among these, the ionic functional group in structural unit UB-2 is preferably anionic functional groups such as carboxyl, sulfonic acid, phosphate, or phosphonic acid groups, or their salts, and particularly preferably carboxyl, sulfonic acid, or their salts. Furthermore, structural unit UB-2 is preferably introduced into the block copolymer (P) by polymerization using a monomer containing an ionic group. Specific examples and preferred examples of monomers containing ionic groups are described for polymer block A.

[0197] Regarding the ionic functional groups possessed by polymer blocks A and B, the block copolymer (P) satisfies at least one of the following conditions I and condition II.

[0198] Condition I: The ionic functional groups of polymer block A are different from those of polymer block B.

[0199] Condition II: The content of ionic functional groups in polymer block A is different from the content of ionic functional groups in polymer block B.

[0200] Regarding condition I above, there is no particular limitation on the combination of ionic functional groups in polymer block A and polymer block B. It should be noted that if at least one of polymer block A and polymer block B has multiple ionic functional groups, each polymer block only needs to have at least one different ionic functional group. As preferred examples of combinations that satisfy condition I, the following [1] to [3] arrangements can be cited.

[0201] [1] In a manner in which one of the polymer block A and the polymer block B has a sulfonic acid group and the other has a carboxyl group.

[0202] [2] In a manner in which one of the polymer block A and the polymer block B has a sulfonic acid group and a carboxyl group, and the other has a carboxyl group.

[0203] [3] One of the polymer blocks A and B has sulfonic acid groups and carboxyl groups, and the other has sulfonic acid groups.

[0204] When the block copolymer (P) satisfies only condition I, the ratio of the content of structural units with ionic functional groups in polymer block A to the content of structural units with ionic functional groups in polymer block B, by mass ratio, is preferably 1 / 99 to 99 / 1, more preferably 5 / 95 to 95 / 5, and even more preferably 10 / 90 to 90 / 10. If it falls within the above range, it is preferable in terms of appropriately adjusting the adsorption to abrasive particles, imparting appropriate electrostatic repulsion throughout the block copolymer (P), and improving the suppression effect on the formation of abrasive particle aggregation structures caused by shear force.

[0205] When condition II is met, the content of structural unit UA-2 in polymer block A differs from the content of structural unit UB-2 in polymer block B. The content of structural unit UA-2 in polymer block A and the content of structural unit UB-2 in polymer block B are such that, relative to 100 parts by mass of one, the content of the other is preferably 99 parts by mass or less, more preferably 98 parts by mass or less, and even more preferably 96 parts by mass or less. By setting these ranges, the difference in adsorption to abrasive particles and the workpiece being ground can be further increased between polymer block A and polymer block B, and the formation of agglomerated structures of abrasive particles due to shear force can be appropriately suppressed. The lower limit of the content of the other of structural unit UA-2 and structural unit UB-2 relative to 100 parts by mass is preferably 2 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more.

[0206] It should be noted that the content of structural units derived from monomers containing ionic groups can be further increased in either polymer block A or polymer block B. From the viewpoint of obtaining a polymer with higher dispersion stability of abrasive particles, it is preferable to increase the content of structural units derived from monomers containing ionic groups in polymer block B compared to polymer block A which has structural unit UC.

[0207] Polymer block B may contain structural units (i.e., structural units UC) having alkyl groups with 1 to 10 carbon atoms in the side chain portion. Preferably, polymer block B does not contain structural units UC, which further increases the difference in adsorption of abrasive particles and the object being abraded within one polymer molecule and further suppresses the formation of agglomerated structures of abrasive particles due to shear force. Specifically, in polymer block B, the content of structural units UC relative to the total constituent monomer units of polymer block B is preferably 0% by mass or more and 10% by mass or less, more preferably 0% by mass or more and 5% by mass or less, and even more preferably 0% by mass or more and 1% by mass or less.

[0208] For polymer block B, the number-average molecular weight (Mn) converted from sodium polyacrylate as determined by GPC is preferably in the range of 1,000 or more and 100,000 or less. If Mn is 1,000 or more, it is preferable in terms of fully demonstrating the improved dispersion stability of the abrasive particles due to the introduction of polymer block B. Furthermore, if Mn is 100,000 or less, it is preferable in terms of sufficiently suppressing the formation of abrasive particle aggregation structures by adsorption of one polymer molecule onto the surfaces of multiple abrasive particles. More preferably, the Mn of polymer block B is 1,500 or more, further preferably 2,000 or more, and even more preferably 3,000 or more. Furthermore, more preferably, the Mn of polymer block B is 70,000 or less, further preferably 50,000 or less, and particularly preferably 40,000 or less.

[0209] <Preparation of Block Copolymer (P)>

[0210] The block copolymer (P) of this embodiment is not particularly limited in its manufacturing method as long as it has two or more different chain segments, and can be manufactured using known manufacturing methods. For a detailed explanation of the manufacturing method of the block copolymer (P), please refer to the description of the first embodiment above. As for the manufacturing method of the block copolymer (P), the same as in the first embodiment, a living radical polymerization method with an exchange chain mechanism or a binding-dissociation mechanism is preferred, more preferably the RAFT method or the NMP method, and particularly preferably the RAFT method.

[0211] For the block copolymer (P) of this embodiment, the number-average molecular weight (Mn) converted from sodium polyacrylate by GPC is preferably in the range of 2,000 or more and 200,000 or less. If Mn is 2,000 or more, it is preferable in that it can sufficiently ensure the wettability of the surface of the object being ground while suppressing the decrease in grinding rate. Furthermore, if Mn is 200,000 or less, it is preferable in that it can sufficiently suppress the agglomeration of abrasive grains due to shear force and sufficiently suppress the generation of defects such as scratches during grinding. From this viewpoint, the Mn of the block copolymer (P) is more preferably 2,500 or more, further preferably 3,000 or more, and even more preferably 4.00 or more. Regarding the upper limit of the Mn of the block copolymer (P), it is more preferably 100,000 or less, further preferably 80,000 or less, even more preferably 70,000 or less, and particularly preferably 60,000 or less.

[0212] The weight-average molecular weight (Mw) of the block copolymer (P), converted from sodium polyacrylate as determined by GPC, is preferably in the range of 3,000 or more and 250,000 or less. More preferably, the Mw of the block copolymer (P) is 4,000 or more, further preferably 6,000 or more, and even more preferably 10,000 or more. Regarding the upper limit of the Mw of the block copolymer (P), more preferably 150,000 or less, further preferably 120,000 or less, and even more preferably 80,000 or less.

[0213] The molecular weight dispersibility (PDI = (Mw / Mn)) expressed as the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn of the block copolymer (P) is preferably 2.5 or less. For polymers exhibiting abrasive dispersion function, molecular weight is considered to influence the adsorption-desorption rate on the abrasive object; generally, the smaller the molecular weight of the polymer, the higher the adsorption-desorption rate on the abrasive object. Furthermore, polymers with large molecular weights are considered to be more prone to forming agglomerated abrasive structures due to shear forces. Therefore, polymers used in abrasive dispersant applications preferably have a narrow molecular weight distribution. From this perspective, the PDI of the block copolymer (P) is more preferably 2.2 or less, further preferably 2.0 or less, and even more preferably 1.7 or less. The lower limit of PDI is typically 1.0.

[0214] From the viewpoint of suppressing the formation of agglomerated structures of abrasive particles due to shear force, the mass ratio A / B of polymer block A to polymer block B in the 1-molecule block copolymer (P) is preferably set to 5 / 95 to 95 / 5. A / B ratio is more preferably 10 / 90 to 90 / 10, further preferably 15 / 85 to 85 / 15, even more preferably 20 / 80 to 80 / 20, and particularly preferably 25 / 75 to 75 / 25. It should be noted that the ratio A / B can be appropriately selected by adjusting the ratio of the monomers used in the manufacture of polymer block A and the monomers used in the manufacture of polymer block B.

[0215] As long as the block copolymer (P) has polymer blocks A and B, the number and arrangement order of polymer blocks A and B within one molecule are not particularly limited. For specific examples of the block structure in the block copolymer (P), the description of the first embodiment described above can be referenced. Among these, the block copolymer (P) of this embodiment is preferably a diblock copolymer with an AB-type structure, which is preferred in terms of being able to efficiently manufacture abrasive grains (especially cerium oxide) with sufficiently high dispersion stability.

[0216] The dispersant of the present invention only needs to contain a block copolymer (P). Therefore, the dispersant can be in the form of a single component containing only the block copolymer (P), or it can be in the form of containing components (other components) different from the block copolymer (P) together with the block copolymer (P).

[0217] The dispersant of the present invention may include a solvent as another component. Examples of solvents include water, organic solvents, and mixtures of water and organic solvents. Among these, the solvent contained in the dispersant is preferably a solvent capable of dissolving the block copolymer (P) as a water-soluble polymer, more preferably water, or a mixture of water and an organic solvent capable of dissolving in water, and particularly preferably water. Specific examples of organic solvents used with water can be found in the description of the first embodiment described above. One type of organic solvent may be used alone, or two or more may be used in combination.

[0218] When the dispersant contains a block copolymer (P) and a solvent, from the viewpoint of ensuring sufficient contact between the surface of the workpiece and the abrasive pad and the block copolymer (P), the content of the block copolymer (P) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total mass of the block copolymer (P) and the solvent. Furthermore, regarding the upper limit of the block copolymer (P) content, from the viewpoint of suppressing reduced processability due to excessively high viscosity, it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, relative to the total mass of the block copolymer (P) and the solvent.

[0219] Abrasive Compositions

[0220] The abrasive composition of this embodiment contains cerium oxide (cerium dioxide) as abrasive particles and the aforementioned dispersant. Cerium oxide has the following advantages: it can grind the surface at a higher grinding speed than silicon dioxide, alumina, etc., and it has a lower hardness than alumina, etc., thus suppressing the generation of defects on the ground surface. The description of the cerium oxide used, the cerium oxide content in the abrasive composition, the solvent, the preparation method of the abrasive composition, etc., can be found in the description of the first embodiment described above.

[0221] The abrasive composition of this embodiment contains a block copolymer (P) as a dispersant, thus exhibiting high dispersion stability of abrasive particles (especially cerium oxide particles) and a high effect in suppressing abrasive particle aggregation caused by shear force. Therefore, the abrasive composition of the present invention is suitable for use as an abrasive fluid in the manufacturing process of semiconductor devices for planarizing the surface of at least one of insulating films and metal wirings, specifically for example, planarizing oxide films (such as silicon oxide films) during shallow trench isolation (STI) fabrication, planarizing the surface of metal wirings including copper, copper alloys, aluminum alloys, etc., and planarizing the surface of interlayer insulating films (oxide films), thereby reducing the generation of defects and obtaining insulating films and metal wirings with excellent surface smoothness.

[0222] Example 2

[0223] The present invention will now be specifically described through examples, but the present invention is not limited to these examples. It should be noted that, unless otherwise specified, “parts” and “%” refer to “parts by mass” and “% by mass”, respectively. The molecular weight of the polymer was determined using the same conditions as in [Example 1] of the first embodiment described above, by measuring the equivalent value of sodium polyacrylate using GPC.

[0224] 1. Polymer Synthesis

[0225] [Synthesis Example 1B]

[0226] In a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, 200g of pure water, 50.2g of acrylic acid (hereinafter referred to as "AA"), 0.056g of 4,4'-azobis(4-cyanopentanoic acid) (hereinafter referred to as "ACVA") as an initiator, and 2.55g of 3-((((1-carboxyethyl)thio)thio)propionic acid (manufactured by BORONMOLECULAR, hereinafter referred to as "BM1429") as a RAFT agent were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was water-cooled to stop the reaction. Next, 200g of pure water, 50.2g of 2-acrylamido-2-methylpropanesulfonic acid (hereinafter referred to as "ATBS"), and 0.072g of ACVA were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. Four hours later, the reaction was stopped by water cooling. The polymerization rates of AA and ATBS, determined by gas chromatography (GC) and NMR, were 97% and 85%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer A2") was determined by GPC, with Mn of 9650, Mw of 12500, and PDI of 1.3.

[0227] [Synthesis Example 2B]

[0228] Methanol (165 g), AA (33.2 g), N-tert-butylacrylamide (8.31 g) (hereinafter also referred to as "TBAM"), 2,2'-azobis(2,4-dimethylpentanonitrile) (manufactured by Wako Pure Chemical Industries Co., Ltd., hereinafter also referred to as "V-65") (0.497 g), and BM1429 (2.11 g) as initiators were added to a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55°C. After 6 hours, the reaction was stopped by water cooling. The solvent was then removed by evaporation, and the precipitated V-65 and unreacted TBAM, which were obtained by adding pure water (425 g), were recovered by filtration. The total amount of filtrate, AA (37.4 g), ATBS (4.20 g), and ACVA (0.056 g) were then added, and the mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. Four hours later, the reaction was stopped by water cooling. The polymerization rates of AA·TBAM and AA·ATBS, determined by GC, were 90% and 85%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer B2") was determined by GPC, with Mn of 13600, Mw of 20400, and PDI of 1.5.

[0229] [Synthesis Example 3B]

[0230] Methanol (190 g), AA (48.2 g), V-65 (0.288 g), and BM1429 (2.11 g) were added to a 1 L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55 °C. After 6 hours, the mixture was cooled with water to stop the reaction. Then, methanol (190 g), AA (46.3 g), TBAM (1.93 g), and V-65 (0.145 g) were added, and the mixture was thoroughly degassed by bubbling with nitrogen. Polymerization was initiated in a constant temperature bath at 55 °C. After 6 hours, the mixture was cooled with water to stop the reaction. The polymerization rates of AA and AA·TBAM, determined by GC, were 87% and 90%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer C2") was determined by GPC, with Mn of 18900, Mw of 24600, and PDI of 1.3.

[0231] [Synthetic Examples 4B, 5B, 9B]

[0232] The raw materials were changed as shown in Table 3, and the same procedures as in Synthesis Example 3B were performed to obtain water-soluble block copolymers (polymers D2, E2, and I2). The molecular weights of polymers D2, E2, and I2 determined by GPC are shown in Table 4.

[0233] [Synthesis Example 6B]

[0234] In a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, 330g of N,N-dimethylformamide (hereinafter referred to as "DMF"), 82.8g of AA, 0.213g of V-65, and 0.681g of BM1429 were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55°C. After 6 hours, the mixture was cooled with water to stop the reaction. Next, 55g of DMF, 10.6g of ATBS, 3.30g of TBAM, and 0.143g of V-65 were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55°C. After 6 hours, the mixture was cooled with water to stop the reaction. The solvent was removed using an evaporator, and the solution was adjusted to a 20% aqueous solution with pure water. The polymerization rates of AA and ATBS·TBAM, determined by GC, were 80% and 82%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer F2") was determined by GPC, with Mn of 42,500, Mw of 72,300, and PDI of 1.7.

[0235] [Synthetic Examples 7B and 8B]

[0236] The raw materials were changed as shown in Table 3, and the same procedures as in Synthesis Example 6B were performed to obtain water-soluble block copolymers (polymers G2 and H). The molecular weights of polymers G2 and H2 determined by GPC are shown in Table 4.

[0237] [Comparative Synthesis Example 1B]

[0238] DMF (365g), ATBS (73.6g), TBAM (18.4g), V-65 (0.544g), and BM1429 (0.936g) were added to a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55°C. After 6 hours, the mixture was water-cooled to stop the reaction. The polymerization rates of ATBS and TBAM, determined by GC and NMR respectively, showed a total reaction rate of 90%. The molecular weight of the resulting random copolymer (denoted as "polymer J2") was determined by GPC: Mn = 15800, Mw = 28400, and PDI = 1.8.

[0239] [Comparative Synthesis Example 2B]

[0240] The raw materials were changed as shown in Table 3, and the same procedures as in Comparative Synthesis Example 1B were performed to obtain polymer K2. The molecular weight of polymer K2 determined by GPC is shown in Table 4.

[0241] [Table 3]

[0242]

[0243] It should be noted that the abbreviations of the compounds in Table 3 are as follows.

[0244] AA: Acrylic acid

[0245] ATBS: 2-Acrylamide-2-methylpropanesulfonic acid

[0246] MA: Methyl acrylate

[0247] TBAM: N-tert-butylacrylamide

[0248] ACVA: 4,4'-Azobis(4-cyanopentanoic acid)

[0249] V-65: 2,2'-Azobis(2,4-dimethylpentanonitrile)

[0250] MeOH: Methanol

[0251] DMF: N,N-dimethylformamide

[0252] BM1429: 3-((((1-Carboxyethyl)thio)thiocarbonyl))thio)propionic acid

[0253] 2. Measurement and Evaluation

[0254] [Example 1B]

[0255] As a dispersant, an aqueous solution containing polymer A2 at a solids concentration of 20% was prepared. 4.0 g of cerium oxide nanoparticles (20 nm primary particle size) and 2 g of dispersant were added to a 50 mL glass pressure-resistant bottle and mixed thoroughly. The pH was adjusted to 7 using a 0.5 mol / L HCl solution or a 25% (w / w) NH3 aqueous solution. Subsequently, 20 g of 1 mm diameter zirconia beads were added, and the mixture was stirred for 30 minutes with a paint shaker. After filtering to remove the beads, the mixture was allowed to stand overnight to obtain a slurry-like abrasive composition. The obtained abrasive composition was used for the following determinations and evaluations. The results of the determinations and evaluations are shown in Table 4.

[0256] <Slurry viscosity>

[0257] The shear viscosity [mPa·s] of the prepared abrasive composition was determined under the following conditions.

[0258] ○ Measurement conditions

[0259] Device body: Physical MCR301 manufactured by Anton Paar

[0260] Measurement temperature: 25℃

[0261] Slip speed range: 1 [s] -1 ]~1000[s -1 ]

[0262] It can be said that the lower the viscosity of the slurry, the less likely the cerium oxide particles will aggregate due to shear force, resulting in excellent dispersion stability. It should be noted that for particles that have settled overnight, each container is redispersed by hand shaking, and the viscosity of the abrasive composition in this redispersed state is measured.

[0263] <Pulp Appearance>

[0264] The appearance of the prepared abrasive composition is visually confirmed to determine the appearance of the slurry. The determination is first performed as in Example 1B, except that no dispersant is added, to prepare a slurry-like abrasive composition as a reference sample. This reference sample is left to stand for 24 hours, and the settling thickness D is measured. This measured settling thickness D is recorded as 100%, and the degree of particle settling [%] of each abrasive composition is calculated. The determination criteria are as follows. It should be noted that for particles that settle overnight, each container is manually shaken to redisperse, and particle settling is confirmed within 1 hour after redispersing.

[0265] ◎: Particle settling within 1 hour is less than 5%.

[0266] ○: Particle settling within 1 hour is greater than 5% and less than 15%.

[0267] △: Particle settling within 1 hour is greater than 15% and less than 30%.

[0268] ×: Particle settling within 1 hour is greater than 30%.

[0269] [Examples 2B-9B, Comparative Examples 1B and 2B]

[0270] The polymers used were changed as described in Table 4. Apart from this, the dispersants were prepared in the same manner as in Example 1B, and slurry-like abrasive compositions were prepared using the same procedures as in Example 1B. The resulting abrasive compositions were subjected to slurry viscosity determination and slurry appearance evaluation in the same manner as in Example 1B. The results are shown in Table 4.

[0271] [Table 4]

[0272]

[0273] It should be noted that in Table 4, the values ​​of monomer 1 and monomer 2 in the "Polymer Block A" and "Polymer Block B" columns represent the monomer composition (mass ratio) of each polymer calculated from the amount of monomer added during polymerization. The "A / B mass ratio" represents the ratio (mass ratio) of polymer block A to polymer block B in each polymer calculated from the monomer composition of each polymer. The values ​​in the "Mn of each block" column are the design values ​​of Mn for each polymer block A and polymer block B, and the Mn, Mw, and PDI in the "Polymer Molecular Weight Properties" column are measured values ​​determined using GPC.

[0274] Based on the results of Examples 1B to 9B, it is evident that by using a block copolymer (P) containing polymer blocks A and B as a dispersant, sedimentation of cerium oxide particles is difficult to occur, resulting in a slurry in which cerium oxide particles are stably dispersed within the system. Furthermore, it is shown that the slurry containing the block copolymer (P) has a viscosity as low as 20 mPa·s, making agglomeration of cerium oxide particles due to shear force difficult to occur.

[0275] In contrast, in Comparative Examples 1B and 2B, which used random copolymers instead of block copolymers (P), the cerium oxide particles showed a greater degree of sedimentation. Furthermore, the slurry viscosity was as high as 30 mPa·s and 44 mPa·s, respectively, which is a result of the poor dispersion stability of the cerium oxide particles.

[0276] [Third Implementation]

[0277] Next, the dispersant and abrasive composition of the third embodiment will be described.

[0278] Dispersants

[0279] The dispersant in the third embodiment of the present invention contains a block copolymer (P) as a water-soluble polymer, the block copolymer (P) having polymer block A and polymer block B, the polymer block A having a structural unit derived from a vinyl monomer as shown in formula (1) below, and the polymer block B being a segment of monomer composition different from that of polymer block A and having a structural unit derived from a vinyl monomer as shown in formula (1) below.

[0280] CH2=CR 1 -C(=O)-NR 2 -R 3 …(1)

[0281] (In equation (1), R) 1 R is a hydrogen atom or a methyl group; 2 and R 3 Each is independently a hydrogen atom, or a substituted or unsubstituted monovalent hydrocarbon group, or R 2 With R 3 For mutual bonding with R 2 and R 3 The bonded nitrogen atoms together form a ring group.

[0282] <Block copolymer (P)>

[0283] • Polymer block A

[0284] Polymer block A has a structural unit (hereinafter also referred to as "structural unit UA-3") derived from the vinyl monomer shown in formula (1) above (hereinafter also referred to as "specific vinyl monomer"). The specific vinyl monomer is one having a primary amide group (-CONH2) and a secondary amide group (-CONHR). 2 -CONHR 3 ) or tertiary amide group (-CONR) 2 R 3 The vinyl monomer of ). In the above formula (1), R 2 and R 3 When at least one of the groups is a substituted monovalent hydrocarbon group, examples of such substituted monovalent hydrocarbon groups include groups having a secondary amino group, groups having a tertiary amino group, and hydroxyalkyl groups. 2 With R 3 In groups that bond together with nitrogen atoms to form a ring, in addition to nitrogen atoms, heteroatoms such as oxygen atoms may also be included as atoms constituting the ring.

[0285] Specific examples of particular vinyl monomers include (meth)acrylamide, (di)alkyl(meth)acrylamides, (di)alkylaminoalkylamides, heterocyclic (meth)acrylamides, and hydroxyl-containing (meth)acrylamides. Specific examples of these include (meth)acrylamide, (di)alkyl(meth)acrylamides, (di)alkylaminoalkylamides, heterocyclic (meth)acrylamides, and hydroxyl-containing (meth)acrylamides, which are exemplified as vinyl monomers containing amide groups constituting structural unit UA in the first embodiment described above.

[0286] From the viewpoint of obtaining a polymer with high solubility in water, the specific vinyl monomer constituting structural unit UA-3 is preferably a water-soluble monomer. Among the specific vinyl monomers constituting structural unit UA-3, vinyl monomers having at least one of a primary amide group and a hydroxyl group are preferred, and at least one selected from (meth)acrylamide and 2-hydroxyethylacrylamide is particularly preferred. It should be noted that "water-soluble monomer" refers to a compound with a solubility of 2 g or more per 100 g of water at 20°C.

[0287] Polymer block A may be a block consisting solely of structural unit UA-3. Without impairing the function of the block copolymer (P), it may further have structural units derived from monomers different from the specific vinyl monomer (hereinafter also referred to as "other monomers M1-3"). Other monomers M1-3 are not particularly limited as long as they are monomers capable of copolymerizing with the specific vinyl monomer. Examples of other monomers M1-3 include, for instance, ester-containing vinyl monomers, alkyl vinyl ethers, vinyl alcohols, aromatic vinyl compounds, vinyl ester compounds, α-olefins, unsaturated acids, and unsaturated anhydrides.

[0288] Specific examples of other monomers M1-3 include, for example, ester-containing vinyl monomers such as alkyl methacrylates, aliphatic cyclic esters of (meth)acrylate, aromatic esters of (meth)acrylate, alkoxyalkyl methacrylates, hydroxyalkyl methacrylates, dialkylaminoalkyl methacrylates, epoxy-containing (meth)acrylates, and polyoxyalkylene (meth)acrylates, which are examples of alkyl vinyl ethers, vinyl alcohols, aromatic vinyl compounds, vinyl ester compounds, α-olefins, unsaturated acids, and unsaturated anhydrides, which are examples of other monomers M1 that can be used in the manufacture of polymer block A in the first embodiment described above. Other monomers M1-3 can be used alone or in combination of two or more. Among these, vinyl monomers containing ester groups are preferred.

[0289] The polymer block A, together with the structural unit UA-3, may also contain a structural unit (structural unit UC) having an alkyl group having 1 to 10 carbon atoms in its side chain portion. The presence of the structural unit UC in the polymer block A is advantageous in terms of improved hydrophobicity and enhanced adsorption to abrasive particles (especially cerium oxide). From the viewpoint of further improving the dispersion stability of the abrasive particles, the alkyl group having 2 or more carbon atoms in the side chain portion of the structural unit UC is preferred. Regarding the upper limit of the number of carbon atoms in the alkyl group having 8 or fewer carbon atoms, more preferably 7 or fewer carbon atoms, from the viewpoint of obtaining a polymer with high solubility in water systems, this alkyl group is preferably bonded to the main chain via a linking group (-COO-, -CONH-, etc.).

[0290] The monomer constituting the structural unit UC is preferably a vinyl monomer containing an ester group. Among these, those with a high effect on improving the dispersion stability of abrasive particles are preferably alkyl methacrylates in which the alkyl group of the alkyl ester portion has 1 to 10 carbon atoms, and more preferably alkyl methacrylates in which the alkyl group of the alkyl ester portion has 2 to 10 carbon atoms. It should be noted that the polymer block A may have only one type of structural unit UC, or it may have two or more types.

[0291] In polymer block A, the content of structural unit UA-3 relative to all constituent monomer units of polymer block A is preferably 30% by mass or more. If the content of structural unit UA-3 is 30% by mass or more, it is suitable for further improving the dispersion stability of the abrasive particles. From this viewpoint, the content of structural unit UA-3 relative to all constituent monomer units of polymer block A is more preferably 40% by mass or more, further preferably 50% by mass or more, even more preferably 60% by mass or more, and particularly preferably 80% by mass or more. Regarding the upper limit of the content of structural unit UA-3, if structural units derived from other monomers are introduced, the content is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less relative to all constituent monomer units of polymer block A.

[0292] When polymer block A has structural unit UC, from the viewpoint of improving the adsorption of abrasive particles and fully obtaining the effect of improving the dispersion stability of abrasive particles, the content of structural unit UC is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, relative to all the constituent monomer units of polymer block A. Regarding the upper limit of the content of structural unit UC, relative to all the constituent monomer units of polymer block A, it is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less.

[0293] The number-average molecular weight (Mn) of polymer block A is preferably in the range of 1,000 or more and 200,000 or less. If Mn is 1,000 or more, it is preferable in terms of fully demonstrating the improved adsorption capacity of the abrasive particles due to the introduction of polymer block A. Furthermore, if Mn is 200,000 or less, it is preferable in terms of sufficiently suppressing the formation of abrasive particle aggregation structures by adsorbing one polymer molecule onto the surfaces of multiple abrasive particles. The Mn of polymer block A is more preferably 1,500 or more, further preferably 2,000 or more, and even more preferably 3,000 or more. Furthermore, regarding the upper limit of Mn of polymer block A, it is more preferably 150,000 or less, further preferably 100,000 or less, and particularly preferably 70,000 or less. It should be noted that the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polymer are values ​​converted from sodium polyacrylate measured by GPC. Specifically, they are values ​​measured by the method described in the examples described later.

[0294] • Polymer block B

[0295] Polymer block B has a structural unit derived from a specific vinyl monomer (hereinafter also referred to as "structural unit UB-3"). A specific example of the specific vinyl monomer is the vinyl monomer illustrated in the description of structural unit UA-3 of polymer block A. From the viewpoint of improving the adsorption of abrasive particles and improving the dispersion stability of abrasive particles, structural units UA-3 and UB-3 in one polymer molecule are preferably structural units derived from different specific vinyl monomers. It should be noted that if at least one of polymer block A and polymer block B has multiple structural units derived from specific vinyl monomers, it is sufficient that each polymer block has at least one different structural unit derived from the specific vinyl monomer, preferably all of them are different.

[0296] From the viewpoint of obtaining a polymer with high solubility in water, the specific vinyl monomer constituting structural unit UB-3 is preferably a water-soluble monomer, wherein it is preferably a vinyl monomer having at least one of secondary amide and tertiary amide groups. Specifically, the specific vinyl monomer constituting structural unit UB-3 is preferably selected from at least one of N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-ethyl-N-methylacrylamide, 2-hydroxyethylacrylamide, and 4-(meth)acryloylmorpholine. In particular, when structural unit UA-3 has at least one of primary amide and hydroxyl groups, and structural unit UB-3 has at least one of secondary amide and tertiary amide groups, the difference in adsorption to abrasive particles and the workpiece being ground can be further increased between chain segments, and the effect of suppressing the formation of agglomerated structures of abrasive particles caused by shear force can be improved, which is therefore preferred.

[0297] Polymer block B may be a block consisting solely of structural unit UB-3, and may further have structural units derived from monomers different from the specific vinyl monomer (hereinafter also referred to as "other monomers M2-3"), without impairing the function of the block copolymer (P). Other monomers M2-3 are not particularly limited as long as they are monomers capable of copolymerizing with the specific vinyl monomer. As a specific example of other monomers M2-3, other monomers M1-3 illustrated in the description of polymer block A can be shown.

[0298] Polymer block B, together with structural unit UB-3, may also contain structural units having carboxyl groups (hereinafter also referred to as "structural unit UD"). By preparing polymer block B having structural unit UD, it is suitable for further improving the dispersion stability of abrasive particles. As monomers constituting structural unit UD, vinyl monomers having carboxyl groups are preferred, such as (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, etc., among which (meth)acrylic acid is particularly preferred. It should be noted that the carboxyl groups of structural unit UD can form salts with counterions such as sodium ions, magnesium ions, and calcium ions. Polymer block B may have only one type of structural unit UD, or it may have two or more types.

[0299] In polymer block B, the content of the structural unit UB-3 derived from a specific vinyl monomer is preferably 1% by mass or more relative to the total constituent monomer units of polymer block B. If the content of structural unit UB-3 is 1% by mass or more, it is suitable for further improving the dispersion stability of the abrasive particles. The content of structural unit UB-3 relative to the total constituent monomer units of polymer block B is more preferably 2% by mass or more, and even more preferably 5% by mass or more. The upper limit for the content of structural unit UB-3 can be set within a range of 100% by mass or less.

[0300] When polymer block B has structural unit UD, the content of structural unit UD is preferably 5% by mass or more, more preferably 10% by mass or more, relative to the total constituent monomer units of polymer block B, from the viewpoint of fully obtaining the improved effect of the introduction of structural unit UD on the dispersion stability of abrasive particles. There is no particular limitation on the upper limit of the content of structural unit UD, but it is preferably set to, for example, 95% by mass or less relative to the total constituent monomer units of polymer block B.

[0301] The number-average molecular weight (Mn) of polymer block B is preferably in the range of 1,000 or more and 200,000 or less. If Mn is 1,000 or more, it is preferable to fully exhibit the improved abrasive particle dispersibility effect caused by the introduction of polymer block B. Furthermore, if Mn is 200,000 or less, it is preferable to sufficiently suppress the formation of agglomerated structures of abrasive particles caused by the adsorption of one polymer molecule on the surfaces of multiple abrasive particles. The Mn of polymer block A is more preferably 1,500 or more, further preferably 2,000 or more, and even more preferably 3,000 or more. Regarding the upper limit of Mn of polymer block B, it is more preferably 150,000 or less, further preferably 100,000 or less, and particularly preferably 70,000 or less.

[0302] <Preparation of Block Copolymer (P)>

[0303] The block copolymer (P) of this embodiment is not particularly limited in its manufacturing method as long as it has two or more different chain segments, and can be manufactured using known manufacturing methods. For a detailed explanation of the manufacturing method of the block copolymer (P), please refer to the description of the first embodiment above. As for the manufacturing method of the block copolymer (P), the same as in the first embodiment, a living radical polymerization method with an exchange chain mechanism or a binding-dissociation mechanism is preferred, more preferably the RAFT method or the NMP method, and particularly preferably the RAFT method.

[0304] For the block copolymer (P) of this embodiment, the number-average molecular weight (Mn) converted from sodium polyacrylate by GPC is preferably in the range of 1,000 or more and 150,000 or less. If Mn is 1,000 or more, it is preferable in that it can sufficiently ensure the wettability of the surface of the object being ground while suppressing the decrease in grinding rate. Furthermore, if Mn is 150,000 or less, it is preferable in that it can sufficiently suppress the agglomeration of abrasive grains due to shear force and sufficiently suppress the generation of defects such as scratches during grinding. From this viewpoint, the Mn of the block copolymer (P) is more preferably 1,500 or more, further preferably 2,000 or more, and even more preferably 3,000 or more. Regarding the upper limit of the Mn of the block copolymer (P), it is more preferably 100,000 or less, further preferably 80,000 or less, even more preferably 70,000 or less, and particularly preferably 50,000 or less.

[0305] The weight-average molecular weight (Mw) of the block copolymer (P), converted from sodium polyacrylate as determined by GPC, is preferably in the range of 1,500 or more and 150,000 or less. The Mw of the block copolymer (P) is more preferably 2,500 or more, and even more preferably 3,500 or more. Regarding the upper limit of the Mw of the block copolymer (P), it is more preferably 100,000 or less, even more preferably 80,000 or less, and even more preferably 70,000 or less.

[0306] The molecular weight dispersibility (PDI = (Mw / Mn)) expressed as the ratio of the weight-average molecular weight Mw to the number-average molecular weight Mn of the block copolymer (P) is preferably 2.2 or less. For polymers exhibiting abrasive dispersion function, molecular weight is considered to influence the adsorption-desorption rate on the abrasive object; generally, the smaller the molecular weight of the polymer, the higher the adsorption-desorption rate on the abrasive object. Furthermore, polymers with large molecular weights are considered to be more prone to forming agglomerated abrasive structures due to shear forces. Therefore, polymers used in abrasive dispersant applications preferably have a narrow molecular weight distribution. From this perspective, the PDI of the block copolymer (P) is more preferably 2.0 or less, further preferably 1.8 or less, even more preferably 1.5 or less, and particularly preferably 1.3 or less. The lower limit of PDI is typically 1.0.

[0307] From the viewpoint of suppressing the formation of agglomerated structures of abrasive particles due to shear force, the mass ratio A / B of polymer block A to polymer block B in the 1-molecule block copolymer (P) is preferably set to 5 / 95 to 95 / 5. A / B ratio is more preferably 10 / 90 to 90 / 10, further preferably 15 / 85 to 85 / 15, and even more preferably 20 / 80 to 80 / 20. It should be noted that the ratio A / B can be appropriately selected by adjusting the ratio of the monomers used in the manufacture of polymer block A and the monomers used in the manufacture of polymer block B.

[0308] As long as the block copolymer (P) has polymer blocks A and B, the number and arrangement order of polymer blocks A and B within one molecule are not particularly limited. For specific examples of the block structure in the block copolymer (P), the description of the first embodiment can be cited. Among these, the block copolymer (P) of this embodiment is preferably a diblock copolymer with an AB-type structure, which is preferred in terms of being able to efficiently manufacture abrasive particles (especially cerium oxide) with sufficiently high dispersion stability.

[0309] The dispersant of the present invention only needs to contain a block copolymer (P). Therefore, the dispersant can be in the form of a single component containing only the block copolymer (P), or it can be in the form of containing components (other components) different from the block copolymer (P) together with the block copolymer (P).

[0310] The dispersant of the present invention may include a solvent as another component. Examples of solvents include water, organic solvents, and mixtures of water and organic solvents. Among these, the solvent contained in the dispersant is preferably a solvent capable of dissolving the block copolymer (P) as a water-soluble polymer, more preferably water, or a mixture of water and an organic solvent capable of dissolving in water, and particularly preferably water. Specific examples of organic solvents used with water can be found in the description of the first embodiment described above. One type of organic solvent may be used alone, or two or more may be used in combination.

[0311] When the dispersant contains a block copolymer (P) and a solvent, from the viewpoint of ensuring sufficient contact between the surface of the workpiece and the abrasive pad and the block copolymer (P), the content of the block copolymer (P) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, relative to the total mass of the block copolymer (P) and the solvent. Furthermore, regarding the upper limit of the block copolymer (P) content, from the viewpoint of suppressing reduced processability due to excessively high viscosity, it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less, relative to the total mass of the block copolymer (P) and the solvent.

[0312] Abrasive Compositions

[0313] The abrasive composition of this embodiment contains cerium oxide (cerium dioxide) as abrasive particles and the aforementioned dispersant. Cerium oxide has the following advantages: it can grind the surface at a higher grinding speed than silicon dioxide, alumina, etc., and it has a lower hardness than alumina, etc., thus suppressing the generation of defects on the ground surface. The descriptions of the cerium oxide used, the cerium oxide content in the abrasive composition, the solvent, and the preparation method of the abrasive composition can be found in the description of the first embodiment described above.

[0314] The abrasive composition of this embodiment contains a block copolymer (P) as a dispersant, thus exhibiting high dispersion stability of abrasive particles (especially cerium oxide particles) and a high effect in suppressing abrasive particle aggregation caused by shear force. Therefore, the abrasive composition of the present invention is suitable for use as an abrasive fluid in the manufacturing process of semiconductor devices for planarizing the surface of at least one of insulating films and metal wirings, specifically for example, planarizing oxide films (such as silicon oxide films) during shallow trench isolation (STI) fabrication, planarizing the surface of metal wirings including copper, copper alloys, aluminum alloys, etc., and planarizing the surface of interlayer insulating films (oxide films), thereby reducing the generation of defects and obtaining insulating films and metal wirings with excellent surface smoothness.

[0315] Example 3

[0316] The present invention will be specifically described below through examples, but the present invention is not limited to these examples. It should be noted that, unless otherwise specified, "parts" and "%" refer to "parts by mass" and "% by mass," respectively. The molecular weight of the polymer was determined using the GPC-converted value of sodium polyacrylate under the same conditions as in [Example 1] of the first embodiment described above.

[0317] 1. Polymer Synthesis

[0318] [Synthetic Example 1C]

[0319] Methanol (165 g), N,N-diethylacrylamide (hereinafter referred to as "DEAA") (42.1 g), 2,2'-azobis(2,4-dimethylpentanonitrile) (manufactured by Wako Pure Chemical Industries Co., Ltd., hereinafter referred to as "V-65") (0.124 g) as initiator, and 3-((((1-carboxyethyl)thio)thio)propionic acid (manufactured by BORON MOLECULAR, hereinafter referred to as "BM1429") (1.07 g) as RAFT agent were added to a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 55°C. After 6 hours, the mixture was water-cooled to stop the reaction. Next, methanol (165g), 2-hydroxyethyl acrylamide (hereinafter referred to as "HEAA") (37.9g), n-butyl acrylate (hereinafter referred to as "BA") (4.21g), and V-65 (0.440g) were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization began in a constant temperature bath at 55°C. After 6 hours, the mixture was water-cooled to stop the reaction. Subsequently, the solvent was removed by evaporation, and the solution was adjusted to a 20% aqueous solution with pure water. The polymerization rates of DEAA and HEAA·BA, determined by gas chromatography (GC), were 85% and 80%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer A3") was determined by GPC: Mn = 20300, Mw = 24400, and PDI = 1.2.

[0320] [Synthetic Examples 2C, 4C-6C]

[0321] The raw materials were changed as shown in Table 5, and the same procedures as in Synthesis Example 1C were performed to obtain water-soluble block copolymers (polymers B3, D3 to F3). The molecular weights of each polymer were determined by GPC and are shown in Table 6.

[0322] [Synthetic Example 3C]

[0323] To a 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube, 205g of pure water, 51.1g of 4-acryloylmorpholine (hereinafter referred to as "ACMO"), 0.035g of 4,4'-azobis(4-cyanopentanoic acid) (hereinafter referred to as "ACVA") as an initiator, and 0.52g of BM1429 were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was cooled with water to stop the reaction. Next, 205g of pure water, 51.1g of acrylamide (hereinafter referred to as "AAm"), and 0.044g of ACVA were added. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was cooled with water to stop the reaction. GC determinations showed that the polymerization rates of ACMO and AAM were 99% and 98%, respectively. The molecular weight of the resulting water-soluble block copolymer (denoted as "polymer C3") was determined by GPC, with Mn of 28,000, Mw of 33,600, and PDI of 1.2.

[0324] [Comparative Synthesis Example 1C]

[0325] A 1L four-necked flask equipped with a stirrer, thermometer, and nitrogen inlet tube was filled with 330g of pure water, 51.0g of AAM, 51.0g of AA, 0.070g of ACVA, and 1.04g of BM1429. The mixture was thoroughly degassed by bubbling with nitrogen, and polymerization was initiated in a constant temperature bath at 70°C. After 4 hours, the mixture was water-cooled to stop the reaction. GC analysis determined the total polymerization percentage of AAM and AA to be 99%. The molecular weight of the resulting random copolymer (denoted as "polymer G3") was determined by GPC: Mn = 9110, Mw = 10900, and PDI = 1.2.

[0326] [Comparative Synthesis Example 2C]

[0327] The raw materials were changed as shown in Table 5, and the same procedures as in Comparative Synthesis Example 1C were performed to obtain polymer H3. The molecular weight of polymer H3 determined by GPC is shown in Table 6.

[0328] [Comparative Synthesis Example 3C]

[0329] The raw materials were changed as shown in Table 5, and the same procedures as in Synthesis Example 3C were performed to obtain polymer I3. The molecular weight of polymer I3 determined by GPC is shown in Table 6.

[0330] [Table 5]

[0331]

[0332] It should be noted that the abbreviations of the compounds in Table 5 are as follows.

[0333] HEAA: 2-Hydroxyethylacrylamide

[0334] DEAA: N,N-Diethylacrylamide

[0335] AAm: Acrylamide

[0336] AA: Acrylic acid

[0337] ACMO: 4-Acryloylmorpholine

[0338] ACVA: 4,4'-Azobis(4-cyanopentanoic acid)

[0339] V-65: 2,2'-Azobis(2,4-dimethylpentanonitrile)

[0340] MeOH: Methanol

[0341] DMF: N,N-dimethylformamide

[0342] BM1429: 3-((((1-Carboxyethyl)thio)thiocarbonyl))thio)propionic acid

[0343] VP: N-vinyl-2-pyrrolidone

[0344] BA: n-Butyl acrylate

[0345] 2. Measurement and Evaluation

[0346] [Example 1C]

[0347] As a dispersant, an aqueous solution containing polymer A3 at a solids concentration of 20% was prepared. 4.0 g of cerium oxide nanoparticles (20 nm primary particle size) and 2 g of dispersant were added to a 50 mL glass pressure-resistant bottle and mixed thoroughly. The pH was adjusted to 7 using a 0.5 mol / L HCl solution or a 25% (w / w) NH3 aqueous solution. Subsequently, 20 g of 1 mm diameter zirconia beads were added, and the mixture was stirred for 30 minutes with a paint shaker. After filtering to remove the beads, the mixture was allowed to stand overnight to obtain a slurry-like abrasive composition. The resulting abrasive composition was used for the following determinations and evaluations. The results of the determinations and evaluations are shown in Table 6.

[0348] <Slurry viscosity>

[0349] The shear viscosity [mPa·s] of the prepared abrasive composition was determined under the following conditions.

[0350] ○ Measurement conditions

[0351] Device body: Physical MCR301 manufactured by Anton Paar

[0352] Measurement temperature: 25℃

[0353] Slip speed range: 1 [s] -1 ]~1000[s -1 ]

[0354] It can be said that the lower the viscosity of the slurry, the less likely the cerium oxide particles will aggregate due to shear force, resulting in excellent dispersion stability. It should be noted that for particles that have settled overnight, each container is redispersed by hand shaking, and the viscosity of the abrasive composition in this redispersed state is measured.

[0355] <Pulp Appearance>

[0356] The appearance of the prepared abrasive composition is visually confirmed to determine the appearance of the slurry. The determination is first performed as in Example 1C, except that no dispersant is added, to prepare a slurry-like abrasive composition as a reference sample. This reference sample is left to stand for 24 hours, and the settling thickness D is measured. This measured settling thickness D is recorded as 100%, and the degree of particle settling [%] of each abrasive composition is calculated. The determination criteria are as follows. It should be noted that for particles that settle overnight, each container is manually shaken to redisperse, and particle settling is confirmed within 1 hour after redispersing.

[0357] ◎: Particle settling within 1 hour is less than 5%.

[0358] ○: Particle settling within 1 hour is greater than 5% and less than 15%.

[0359] △: Particle settling within 1 hour is greater than 15% and less than 30%.

[0360] ×: Particle settling within 1 hour is greater than 30%.

[0361] [Examples 2C-6C, Comparative Examples 1C-3C]

[0362] The polymers used were changed as described in Table 6. Otherwise, the dispersants were prepared in the same manner as in Example 1C, and slurry-like abrasive compositions were prepared using the same procedures as in Example 1C. The resulting abrasive compositions were subjected to slurry viscosity determination and slurry appearance evaluation in the same manner as in Example 1C. The results are shown in Table 6.

[0363] [Table 6]

[0364]

[0365] It should be noted that in Table 6, the values ​​of monomer 1 and monomer 2 in the "Polymer Block A" and "Polymer Block B" columns represent the monomer composition (mass ratio) of each polymer calculated from the input amounts during polymerization. The "A / B mass ratio" represents the ratio (mass ratio) of polymer block A to polymer block B in each polymer, calculated from the monomer composition of each polymer. The values ​​in the "Mn of Each Block" column are the theoretically calculated values ​​of Mn for each polymer block A and polymer block B. The Mn, Mw, and PDI values ​​in the "Polymer Molecular Weight Properties" column are measured values ​​using GPC.

[0366] Based on the results of Examples 1C to 6C, it is evident that by using a block copolymer (P) containing polymer blocks A and B as a dispersant, sedimentation of cerium oxide particles is difficult to occur, resulting in a slurry in which cerium oxide particles are stably dispersed within the system. Furthermore, it is shown that the slurry containing the block copolymer (P) has a viscosity as low as 35 mPa·s or less, making agglomeration of cerium oxide particles due to shear force difficult to occur.

[0367] In contrast, in Comparative Examples 1C and 2C, where a random copolymer was used instead of a block copolymer (P), the cerium oxide particles exhibited significant sedimentation. Furthermore, the slurry viscosity was high, reaching 45 mPa·s and 67 mPa·s respectively, indicating poor dispersion stability of the cerium oxide particles. Further, in Comparative Example 3C, which produced a block copolymer of N-vinyl-2-pyrrolidone (VP) and acrylamide (AAm), the sedimentation degree of the cerium oxide particles was rated as "△", but the slurry viscosity was high, reaching 51 mPa·s, a result of poor dispersion stability of the cerium oxide particles.

Claims

1. A dispersant which is a chemical mechanical polishing dispersant used in surface planarization of at least any one selected from an insulating layer and a wiring layer, the dispersant contains a block copolymer (P) having a polymer block A and a polymer block B, the polymer block A and the polymer block B each have a structural unit derived from a vinyl monomer represented by the following formula (1), the vinyl monomer represented by the following formula (1) being at least one selected from the group consisting of (meth)acrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-ethyl-N-methyl (meth)acrylamide, 4-(meth)acryloylmorpholine, 2-hydroxyethyl acrylamide, and 2-(meth)acrylamido-2-methylpropane sulfonic acid or a salt thereof, a ratio A / B of the polymer block A to the polymer block B in the block copolymer (P) is 10 / 90 to 90 / 10 in terms of mass ratio, a molecular weight dispersity Mw / Mn expressed by a ratio of a number average molecular weight Mn to a weight average molecular weight Mw of the block copolymer (P) is 2.0 or less, and a number average molecular weight Mn of the polymer block A is in a range of 1,000 or more and 200,000 or less, CH2=CR 1 -C(=O)-NR 2 -R 3 …(1) In equation (1), R 1 It is a hydrogen atom or a methyl group; R 2 and R 3 Each is independently a hydrogen atom, or a substituted or unsubstituted monovalent hydrocarbon group, or R 2 With R 3 For mutual bonding with R 2 and R 3 The bonded nitrogen atoms together form a cyclic group.

2. The dispersant of claim 1, wherein, the polymer block A contains a structural unit having at least any one selected from a primary amide group and a hydroxyl group as the structural unit derived from the vinyl monomer represented by the formula (1).

3. The dispersant of claim 1 or 2, wherein, the polymer block B contains a structural unit having at least any one selected from a secondary amide group and a tertiary amide group as the structural unit derived from the vinyl monomer represented by the formula (1).

4. The dispersant of claim 1 or 2, wherein, the polymer block B contains a structural unit having a carboxyl group.

5. A polishing agent composition which is a chemical mechanical polishing agent composition used in surface planarization of at least any one selected from an insulating layer and a wiring layer, the polishing agent composition contains the dispersant according to any one of claims 1 to 4, and cerium oxide.

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