Additive for chemical mechanical polishing, method for producing the same, and polishing composition

Abstract

An additive according to the present invention is configured so as to be used in chemical-mechanical polishing and contains a polymer (P). The polymer (P) has a structural unit (A) derived from a vinyl monomer having a -(LO)n-R group; the total content of structural units derived from monomers including one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof is 0-0.6 mass%; and the polydispersity index (PDI) represented by the weight average molecular weight / number average molecular weight of the polymer (P) is 2.0 or less.　(Note that L is an alkylene group having a carbon number of 4 or less, n is any integer from 3 to 150, and R is a hydrogen atom or a monovalent hydrocarbon group having a carbon number of 1 to 4.)

Description

[Technical Field]

[0001] The present invention relates to an additive for chemical mechanical polishing, a method for producing the same, and a polishing composition, and more particularly to an additive for chemical mechanical polishing (CMP), which is an important process in the manufacturing process of semiconductor devices and the like, a method for producing the same, and a polishing composition. [Background technology]

[0002] Semiconductor devices are used in almost all familiar electronic devices, such as information and communication devices and home appliances, and have become an indispensable part of modern life. In recent years, the role of semiconductor devices has become even greater due to the spread of IoT and the use of cloud computing. To date, the high integration and capacity of semiconductor chips have been achieved at a remarkable speed, but the demand for higher performance continues, and the importance of microfabrication technology is increasing. In particular, chemical mechanical polishing (CMP) technology is extremely important for achieving high-precision multilayer wiring formation, and is frequently used in various stages of the semiconductor device manufacturing process, such as planarizing insulating films, forming metal plugs, and forming buried wiring. In CMP, polishing liquids are used to improve polishing speed and processing accuracy. Polishing liquids generally contain abrasive grains, polishing accelerators, water-soluble polymers, surfactants, etc. Among these, water-soluble polymers and surfactants are added to polishing liquids to improve the flatness of the object to be polished and to suppress surface defects. They protect the surface by adsorbing to the surface of the polishing film and also have the effect of contributing to the suppression of excessive polishing. However, if their adsorption to the polishing film is too strong, there is the problem that a sufficient polishing speed cannot be obtained. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-017195 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-318072 [Patent Document 3] International Publication No. 2009 / 104334 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a polishing composition containing a copolymer of ammonium acrylate and methyl acrylate and cerium oxide particles. It is said that the use of this polishing composition improves the flatness of the polished surface compared to a polishing composition that does not contain an acrylic copolymer. However, the flatness is not sufficient. For example, when the above-mentioned polishing composition is used to polish a film having an uneven surface, not only the convex portions but also the concave portions are polished at the same time, resulting in a phenomenon in which the polished surface, particularly the portions corresponding to the concave portions, bends like a dish. This phenomenon, called dishing, is problematic and is likely to occur when the proportion of the total area of ​​the concave portions visible when the uneven surface is viewed from above is large. In order to suppress the above-mentioned dishing and obtain a highly flat polished surface, Patent Document 2 proposes a polishing composition containing ceria particles as abrasive grains and dihydroxyethylglycine and polyoxyalkylene alkyl ether as additives. The proposal is that these two compounds adsorb to the abrasive grains and the polishing film, respectively, and protect the recesses in the polishing film, thereby preventing over-polishing and obtaining a flat surface. However, because the surfactant has a small molecular weight, it only weakly adsorbs to the polishing film, and the protective effect is insufficient. Patent Document 3 proposes a graft polymer containing an anionic functional group in the backbone polymer and polyalkylene glycol in the branches as a copper dishing-reducing agent. The proposal states that the anionic functional group in the backbone adsorbs to the copper surface, adjusting the polishing rate and resulting in a smooth surface. However, the polishing rate is slowed down, which reduces productivity.

[0005] The present invention has been made in view of the above circumstances, and its object is to provide an additive for chemical mechanical polishing that can sufficiently quickly polish convex portions (oxide films) on the uneven surface to be polished and can significantly reduce dishing, a method for producing the additive, and a polishing composition. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have found that the above problems can be solved by using an additive containing a polymer having a narrow molecular weight distribution and specific structural units. The present invention was completed based on this finding. The present specification provides the following means.

[0007] [1] An additive for chemical mechanical polishing containing a polymer (P), The polymer (P) contains structural units (A) derived from a vinyl monomer having a -(LO)nR group, and has a total content of structural units derived from monomers containing one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof of 0 to 0.6 mass %, and the polymer (P) has a polydispersity index (PDI) expressed as the weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.0 or less. (wherein L is an alkylene group having 4 or less carbon atoms, n is an integer of 3 to 150, and R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms.) [2] The additive according to [1] above, wherein the polymer (P) has a number average molecular weight (Mn) of 1,000 to 100,000. [3] The additive according to [1] or [2], wherein the polymer (P) further contains a structural unit (B) derived from at least one monomer selected from the group consisting of an amide group-containing vinyl monomer and an ester group-containing vinyl monomer (excluding the vinyl monomer having the -(LO)nR group). [4] The additive according to [3], wherein the structural unit (B) is a structural unit derived from a (meth)acrylic acid ester and / or a (meth)acrylic acid amide type monomer. [5] The structural unit (B) has an SP value calculated by the Fedors estimation method of 17 to 25 (J / cm 3 ) 0.5 The additive according to [3] or [4] above, wherein the structural unit is derived from a monomer of [6] The additive according to any one of the above [1] to [5], wherein the polymer (P) is a block polymer. [7] The polymer (P) contains a polymer block A and a polymer block B, The polymer block A has the structural unit (A), The additive according to any one of the above [1] to [6], wherein the polymer block B has the structural unit (B). [8] The additive according to [7], wherein the ratio (A / B) of the polymer block A to the polymer block B in the polymer (P) is 50 / 50 to 99.9 / 0.1 in terms of mass ratio. [9] A polishing composition for chemical mechanical polishing used for planarizing the surface of at least one of an insulating layer and a wiring layer, the polishing composition comprising the additive according to any one of [1] to [8] above and cerium oxide and / or silica.

[10] A method for producing an additive for a chemical mechanical polishing liquid containing a polymer, comprising: The method comprises the step of producing, by a living radical polymerization method, a polymer which contains structural units derived from a vinyl monomer having a -(LO)nR group, and in which the total content of structural units derived from monomers containing one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof is 0 to 0.6 mass%, and which has a polydispersity index (PDI) of 2.0 or less, expressed as the weight average molecular weight (Mw) / number average molecular weight (Mn). (wherein L is an alkylene group having 4 or less carbon atoms, n is an integer of 3 to 150, and R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms.) [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an additive for chemical mechanical polishing that can sufficiently quickly remove convex portions (oxide films) from an uneven surface to be polished and can significantly reduce dishing. It is also possible to provide a polishing composition containing the additive and cerium oxide and / or silica. Furthermore, it is also possible to provide a method for producing an additive for a chemical mechanical polishing liquid that contains a polymer. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described in detail below. In this specification, "(meth)acrylic" means acrylic and / or methacrylic, "(meth)acrylate" means acrylate and / or methacrylate, and "(meth)acryloyl group" means acryloyl group and / or methacryloyl group.

[0010] The present invention provides an additive for chemical mechanical polishing that can sufficiently quickly remove convex portions (oxide films) from an uneven surface to be polished and can significantly reduce dishing, and a polishing composition containing the additive and cerium oxide and / or silica. Furthermore, a method for producing the polymer-containing additive for chemical mechanical polishing is also provided. The additive for chemical mechanical polishing, the polishing composition, and the method for producing the polymer-containing additive for chemical mechanical polishing provided by the present invention will be described in detail below.

[0011] <Additives for chemical mechanical polishing> The additive for chemical mechanical polishing provided by the present invention comprises: It contains a polymer (P), The polymer (P) contains a structural unit (A) derived from a vinyl monomer having a -(LO)nR group. and a structural unit (B) derived from an amide group-containing vinyl monomer (excluding the vinyl monomer having the -(LO)nR group). and the content of structural units derived from monomers containing one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof is 0 to 0.6% by mass in total, and the polydispersity index (PDI) of the polymer (P) expressed as weight average molecular weight (Mw) / number average molecular weight (Mn) is 2.0 or less.

[0012] <Polymer (P)> The polymer (P) used in the present invention contains a structural unit derived from a vinyl monomer having a -(LO)nR group. Examples of L in the polymer (P) include a methylene group, an ethylene group, a -CHMe- group, an n-propylene group, a -CHEt- group, a -CHMeCH2- group, a -CH2CHMe- group, an n-butylene group, a -CH(n-Pr)- group, a -CH(i-Pr)- group, a -CHEtCH2- group, a -CH2CHEt- group, a -CHMeCH2CH2- group, a -CH2CHMeCH2- group, and a -CH2CH2CHMe- group. All Ls in the polymer (P) may be the same group. Alternatively, L in the polymer (P) may contain two or more different groups. Considering the ease of industrial availability of raw materials and the solubility of the polymer (P) in water, L in the polymer (P) is preferably any one of an ethylene group, a -CHMeCH- group, or a -CHCHMe- group, and more preferably an ethylene group.

[0013] In the polymer (P), n is an integer of 3 to 150. Considering that the -(LO)nR groups contained in the polymer (P) contribute to reducing dishing by adsorbing to and protecting oxide films and exhibiting high responsiveness to changes in polishing pressure, the upper limit of n is preferably 100 or less, more preferably 50 or less, even more preferably 30 or less, and even more preferably 15 or less. The lower limit of n is preferably 4 or more, more preferably 5 or more, even more preferably 6 or more, and even more preferably 7 or more. The preferred range of n can be any combination of the numerical values ​​exemplified above as the upper and lower limits. For example, the preferred range of n may be 4 to 100, 5 to 50, 6 to 30, or 7 to 15. When the L is composed of only one type of group, n is any integer within the above range. On the other hand, when the L is composed of two types of groups, the -(LO)nR group is -(L 1 O)n 1 -(L 2 O)n 2-R group, where n 1 and n 2 The total value of L and L is any integer within the above range. The same can be considered when L is composed of three or more types of groups.

[0014] R in the polymer (P) is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms. Examples of the monovalent hydrocarbon group having 1 to 4 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, and a tert-butyl group. In consideration of the availability of industrial raw materials and the solubility of the polymer (P) in water, R in the polymer (P) is preferably a hydrogen atom or a methyl group, and more preferably a methyl group.

[0015] Anionic (co)polymers typically adsorb to the positively charged nitride film surface. This increases the polishing selectivity with respect to the oxide film on the protruding portions, resulting in a flat surface. However, once the nitride film is exposed and polishing nears its end, the polishing rate of the oxide film increases, which may result in dishing. Furthermore, anionic additives can change the stability of the polishing composition due to changes in pH, which can lead to coarsening of abrasive grains and cause polishing scratches. Considering these points, the total content of structural units derived from monomers containing one or more functional groups selected from the group consisting of carboxylic acid groups, phosphoric acid groups, phosphonic acid groups, sulfuric acid groups, sulfonic acid groups, and salts thereof, relative to the entire polymer (P), is preferably 0 to 0.6% by mass. The content of structural units derived from monomers containing one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof relative to the entire polymer (P) is more preferably 0 to 0.5 mass%, even more preferably 0 to 0.4 mass%, even more preferably 0 to 0.3 mass%, and still more preferably 0 to 0.2 mass%.

[0016] The polymer (P) has a polydispersity index (PDI), expressed as the weight-average molecular weight (Mw) / number-average molecular weight (Mn), of 2.0 or less. For polymers with abrasive particle dispersibility, the molecular weight is thought to affect the rate of adsorption / desorption to the polishing target. Generally, the smaller the molecular weight of the polymer, the higher the rate of adsorption / desorption to the polishing target. Furthermore, polymers with a higher molecular weight are thought to be more likely to form abrasive particle aggregation structures due to shear force. Therefore, for polymers with abrasive particle dispersibility, a narrow molecular weight distribution is preferred. From this perspective, the PDI of the polymer (P) is preferably 1.8 or less, more preferably 1.5 or less, even more preferably 1.3 or less, and even more preferably 1.2 or less. The lower limit of the PDI is usually 1.0. In this specification, the number-average molecular weight (Mn) and weight-average molecular weight (Mw) of the polymer are values ​​measured in terms of polystyrene by gel permeation chromatography (GPC). Details of molecular weight measurement are explained in the Examples section.

[0017] The number-average molecular weight (Mn) of the polymer (P) is preferably 1,000 to 100,000. When Mn is 1,000 or more, it is possible to suppress a decrease in the polishing rate while ensuring sufficient wettability of the surface of the object to be polished. Furthermore, when Mn is 100,000 or less, it is possible to sufficiently suppress aggregation of abrasive grains due to shear force, and it is possible to sufficiently suppress the occurrence of defects such as scratches during polishing. From this viewpoint, Mn of the polymer (P) is more preferably 1,500 or more, even more preferably 2,000 or more, and even more preferably 2,500 or more. The upper limit of Mn of the polymer (P) is more preferably 60,000, even more preferably 30,000, even more preferably 10,000, and even more preferably 6,000. The preferred range of the number-average molecular weight can be represented by any combination of the numerical values ​​exemplified as the upper and lower limits above. For example, the preferable range of the molecular weight of the polymer (P) may be 1,500 or more and 60,000 or less, 2,000 or more and 30,000 or less, or 2,500 or more and 10,000 or less.

[0018] The method for producing the polymer (P) will be described in detail below, but for example, the polymer (P) can be produced by polymerizing a monomer component containing a vinyl monomer having the -(LO)nR group. The vinyl monomer having the -(LO)nR group is not particularly limited as long as it is a compound having both a polymerizable vinyl group and a -(LO)nR group. Examples of compounds having a polymerizable vinyl group include ester compounds or amide compounds of unsaturated acids such as (meth)acrylic acid, crotonic acid, maleic acid, and itaconic acid, aromatic vinyl compounds, and vinyl ether compounds.

[0019] Specific examples of the vinyl monomer having the -(LO)nR group that can be used in the present invention include N-[2-[2-(2-methoxyethoxy)ethoxy]ethyl](meth)acrylamide, 1-[(meth)acryloylamino]-3,6,9,12,15,18,21-heptaoxadocosane, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, poly(ethylene glycol-propylene glycol) mono(meth)acrylate, poly(ethylene glycol-tetramethylene glycol) mono(meth)acrylate, poly(ethylene glycol-propylene glycol-tetramethylene glycol) mono(meth)acrylate, monomethoxypolyethylene glycol mono(meth)acrylate, monomethoxypoly Examples include propylene glycol mono(meth)acrylate, monomethoxypolytetramethylene glycol mono(meth)acrylate, monomethoxypoly(ethylene glycol-propylene glycol) mono(meth)acrylate, monomethoxypoly(ethylene glycol-tetramethylene glycol) mono(meth)acrylate, monomethoxypoly(ethylene glycol-propylene glycol-tetramethylene glycol) mono(meth)acrylate, monoethoxypolyethylene glycol mono(meth)acrylate, mono-n-propoxypolyethylene glycol mono(meth)acrylate, mono-i-propoxypolyethylene glycol mono(meth)acrylate, mono-n-butoxypolyethylene glycol mono(meth)acrylate, mono-t-butoxypolyethylene glycol mono(meth)acrylate, etc. Among these, polyethylene glycol mono(meth)acrylate and monomethoxypolyethylene glycol mono(meth)acrylate are preferred, polyethylene glycol monoacrylate and monomethoxypolyethylene glycol monoacrylate are more preferred, and monomethoxypolyethylene glycol monoacrylate is even more suitable. Examples of commercially available products include the Blenmar AE series, AME series, AP series, PE series, PME series, PP series, and 50PEP series manufactured by NOF Corporation, the AM series manufactured by Shin-Nakamura Chemical Co., Ltd., and Light Acrylate MTG-A and Light Acrylate 130A manufactured by Kyoeisha Chemical Co., Ltd. Note that "Blenmar" is a registered trademark of NOF Corporation, and "Light Acrylate" is a registered trademark of Kyoeisha Chemical Co., Ltd.

[0020] The content of the structural unit (A) derived from the vinyl monomer having the -(LO)nR group relative to the entire polymer (P) is preferably 50% by mass or more. The content of the structural unit (A) is more preferably 80% by mass or more, even more preferably 85% by mass or more, even more preferably 90% by mass or more, and even more preferably 93% by mass or more. The upper limit of the structural unit (A) is 100% by mass, preferably 99% by mass, even more preferably 98% by mass, even more preferably 97% by mass, and even more preferably 96% by mass. The preferred range of the content of the structural unit (A) can be expressed by any combination of the numerical values ​​exemplified as the upper and lower limits above. For example, the preferred range of the content of the structural unit (A) may be 50% by mass or more to 100% by mass or less, 80% by mass or more to 99% by mass or less, 85% by mass or more to 98% by mass or less, 90% by mass or more to 97% by mass or less, or 93% by mass or more to 96% by mass or less. When the content of the structural unit derived from the vinyl monomer having the -(LO)nR group is within the above range, the sintered body has a high responsiveness to changes in polishing pressure, and when the oxide film is in a convex portion (when the polishing pressure is high), the sintered body does not adsorb and does not decrease the polishing rate. However, when the polishing progresses and the nitride film is exposed, and the object to be polished becomes a concave portion (when the polishing pressure is low), the sintered body tends to adsorb to the oxide film interface and suppress over-polishing. These effects make it easier to obtain a good polished surface with reduced dishing without reducing the polishing rate.

[0021] The polymer (P) may be a homopolymer of the vinyl monomer having the -(LO)nR group, or a polymer using a plurality of types of vinyl monomers having the -(LO)nR group. Also, the polymer (P) may be a copolymer of the vinyl monomer having the -(LO)nR group and at least one monomer selected from the group consisting of an amide group-containing vinyl monomer and an ester group-containing vinyl monomer (excluding the vinyl monomer having the -(LO)nR group). may be By using at least one monomer selected from the group consisting of amide group-containing vinyl monomers and ester group-containing vinyl monomers, the balance of hydrophilicity / hydrophobicity of the polymer (P) can be adjusted as desired, and the polymer (P) can be appropriately adsorbed to the oxide film interface, thereby preventing over-polishing.

[0022] Examples of the amide group-containing vinyl monomer include (meth)acrylamide, tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, (meth)acryloylmorpholine, and other (meth)acrylamide derivatives, and N-vinylacetamide, N-vinylformamide, N-vinylisobutylamide, and other N-vinylamide monomers. One or more of these may be used. Among these, (meth)acrylamide, tert-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, (meth)acryloylmorpholine, and other (meth)acrylamide derivatives are preferred. Furthermore, the SP value calculated by Fedors' estimation method (see Polymer Engineering & Science, Vol. 14, No. 2, pp. 147-154, 1974) is 17-25 (J / cm 3 ) 0.5 More preferably, the monomer is 18 to 21.8 (J / cm 3 ) 0.5More preferably, the monomers are tert-butyl acrylamide and N-isopropyl acrylamide.

[0023] Examples of the ester group-containing vinyl monomer include vinyl esters such as vinyl acetate and vinyl propionate; methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, amyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, ethylhexyl (meth)acrylate, and (meth)acrylate. alkyl (meth)acrylates such as n-decyl (meth)acrylate; aliphatic cyclic esters of (meth)acrylic acid such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclododecyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentanyl (meth)acrylate; phenyl methacrylate, benzyl (meth)acrylate, phenoxymethyl (meth)acrylate, Aromatic esters of (meth)acrylic acid such as 2-phenoxyethyl (meth)acrylate and 3-phenoxypropyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; N-[2-(methylamino)ethyl](meth)acrylate, N-[2-(dimethylamino)ethyl](meth)acrylate, N-[2-(ethylamino)ethyl](meth)acrylate and N-[2-(diethylamino)ethyl](meth)acrylate (di)alkylaminoalkyl (meth)acrylates such as 4-hydroxybutyl (meth)acrylate glycidyl ether and 3,4-epoxycyclohexylmethyl (meth)acrylate; and alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate and methoxydipropylene glycol (meth)acrylate. Among these, the SP value calculated by the Fedors estimation method is 17 to 25 (J / cm 3 ) 0.5 More preferably, the monomer is 18 to 21.8 (J / cm 3 ) 0.5 More preferably, the monomers are methyl acrylate, ethyl acrylate, n-propyl acrylate, and n-butyl acrylate.

[0024] The polymer (P) further contains an amide group-containing vinyl monomer. body( However, the vinyl monomer having the -(LO)nR group is excluded. There are The content of the structural unit (B) relative to the entire polymer (P), i.e., the sum of the content of structural units derived from the amide group-containing vinyl monomer (excluding the vinyl monomer having the -(LO)nR group) and the content of structural units derived from the ester group-containing vinyl monomer (excluding the vinyl monomer having the -(LO)nR group), is 0% by mass or more. The content of the structural unit (B) is preferably 1% by mass or more, more preferably 2% by mass or more, even more preferably 3% by mass or more, and even more preferably 4% by mass or more. The upper limit of the content of the structural unit (B) is preferably 50% by mass, more preferably 20% by mass, even more preferably 15% by mass, and even more preferably 10% by mass. A preferred range of the content of the structural unit (B) can be expressed by any combination of the above lower and upper limits. For example, the content of the structural unit (B) may preferably range from 1% by mass to 50% by mass, from 2% by mass to 20% by mass, from 3% by mass to 15% by mass, or from 4% by mass to 10% by mass.

[0025] When the total content of the structural units derived from the amide group-containing vinyl monomer and the structural units derived from the ester group-containing vinyl monomer relative to the entire polymer (P) is within the above range, a good polished surface with reduced dishing is more likely to be obtained.

[0026] The polymer (P) may contain, as a structural unit, other copolymerizable monomers in addition to at least one monomer selected from the group consisting of the vinyl monomer having the -(LO)nR group, the amide group-containing vinyl monomer, and the ester group-containing vinyl monomer. Specific examples of other copolymerizable monomers include alkyl vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, t-butyl vinyl ether, n-hexyl vinyl ether, 2-ethylhexyl vinyl ether, n-octyl vinyl ether, n-nonyl vinyl ether, and n-decyl vinyl ether; vinyl alcohols such as vinyl alcohol, 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, and 4-hydroxybutyl vinyl ether; aromatic vinyl compounds such as styrene, vinyl toluene, and vinyl xylene; and α-olefins such as ethylene, propylene, and butylene. As other copolymerizable monomers, one or more of these can be used in combination. The content of the structural units derived from the other copolymerizable monomers in the entire polymer (P) is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 5% by mass or less, still more preferably 3% by mass or less, and even more preferably 1% by mass or less.

[0027] When the polymer (P) is a copolymer containing a vinyl monomer having the -(LO)nR group, its molecular structure is preferably a block copolymer.

[0028] Among the block copolymers, the polymer (P) is a polymer block A having a structural unit (A) derived from a vinyl monomer having the -(LO)nR group, and a vinyl monomer having an amide group. body( However, the vinyl monomer having the -(LO)nR group is excluded.) and a polymer block B having a structural unit (B) derived from the above. Traditionally, water-soluble polymers used as additives for chemical mechanical polishing (CMP) have been homopolymers or random copolymers. However, polymers with functional groups that adsorb to the substrate surface distributed throughout the polymer structure have poor surface protection because the adsorption sites are not uniformly distributed, which can lead to over-polishing under high polishing pressures. On the other hand, block copolymers have a structure in which the functional groups that adsorb to the substrate surface are uniformly distributed, providing sufficient adsorption and preventing over-polishing of the substrate.

[0029] <Block copolymer> The block copolymer that can be suitably used in the present invention is a block copolymer containing a polymer block A and a polymer block B. Polymer block A The polymer block A has a structural unit (A) derived from the vinyl monomer having the -(LO)nR group. The polymer block A may be a homopolymer of the vinyl monomer having the -(LO)nR group, or a polymer using multiple types of vinyl monomers having the -(LO)nR group. Furthermore, as long as the effects of the present invention are not impaired, the polymer block A may be a copolymer of the vinyl monomer having the -(LO)nR group and at least one monomer selected from the group consisting of amide group-containing vinyl monomers and ester group-containing vinyl monomers (excluding the vinyl monomer having the -(LO)nR group), and / or one of the other copolymerizable monomers.

[0030] The content of the structural unit (A) derived from the vinyl monomer having the -(LO)nR group in the entire polymer block A is preferably 80% by mass or more, more preferably 90% by mass or more. The content of the structural unit (A) may be 95% by mass or more, 97% by mass or more, or even 99% by mass or more. The upper limit of the content of the structural unit (A) is 100% by mass. When the content of the structural unit (A) derived from the vinyl monomer having the -(LO)nR group is within the above range, the suction force is high, and when the oxide film is convex (when the polishing pressure is high), the suction force does not adsorb and the polishing rate does not decrease. However, when the polishing progresses and the nitride film is exposed and the object to be polished becomes concave (when the polishing pressure is low), the suction force tends to adsorb to the oxide film interface and suppress over-polishing. These effects make it easier to obtain a good polished surface with reduced dishing without reducing the polishing rate.

[0031] The weight-average molecular weight of the polymer block A is preferably 500 or more, more preferably 900 or more, even more preferably 1,500 or more, even more preferably 2,100 or more, and even more preferably 2,700 or more. The upper limit of the weight-average molecular weight of the polymer block A is preferably 100,000, more preferably 60,000, even more preferably 30,000, even more preferably 10,000, and even more preferably 6,000. A preferred range of the weight-average molecular weight of the polymer block A can be expressed by any combination of these lower and upper limits. For example, the preferred range of the weight-average molecular weight of the polymer block A may be 500 to 100,000, 900 to 60,000, 1,500 to 30,000, 2,100 to 10,000, or 2,700 to 6,000. The weight-average molecular weight of the polymer block A within the above range is preferable because it can sufficiently ensure wettability of the surface of the object to be polished while suppressing a decrease in the polishing rate, and is also preferable because it can sufficiently suppress aggregation of abrasive grains due to shear force and sufficiently suppress the occurrence of defects such as scratches during polishing.

[0032] Polymer block B The polymer block B is a copolymer of the amide group-containing vinyl monomer body( However, the vinyl monomer having the -(LO)nR group is excluded.) The polymer block B has a structural unit (B) derived from the amide group-containing vinyl monomer. body( However, the vinyl monomer having the -(LO)nR group is excluded.) and Ester group-containing vinyl monomer and includes The polymer may be a polymer using two or more kinds of monomers (excluding the vinyl monomer having the -(LO)nR group). In addition, as long as the effect of the present invention is not impaired, the polymer block B may be a polymer using two or more kinds of monomers (excluding the vinyl monomer having the -(LO)nR group). body( However, the vinyl monomer having the -(LO)nR group is excluded.) and the vinyl monomer having the -(LO)nR group and / or the other copolymerizable monomer may be a copolymer.

[0033] The total content of structural units derived from amide group-containing vinyl monomers (excluding vinyl monomers having the -(LO)nR group) and ester group-containing vinyl monomers (excluding vinyl monomers having the -(LO)nR group) relative to the entire polymer block B, i.e., the content of structural units (B), is preferably 80% by mass or more, more preferably 90% by mass or more. The total content of structural units (B) may also be 95% by mass or more, 97% by mass or more, or 99% by mass or more. The upper limit of the total content of the structural units (B) is 100% by mass.

[0034] The weight-average molecular weight of the polymer block B is preferably 100 or more, more preferably 120 or more, even more preferably 130 or more, still more preferably 140 or more, and even more preferably 150 or more. The upper limit of the weight-average molecular weight of the polymer block B is preferably 50,000, more preferably 10,000, even more preferably 5,000, even more preferably 1,000, and still more preferably 500. A preferred range of the weight-average molecular weight of the polymer block B can be expressed by any combination of the above lower and upper limits. For example, the preferred range of the weight-average molecular weight of the polymer block B may be 100 to 50,000, 120 to 10,000, 130 to 5,000, 140 to 1,000, or 150 to 500.

[0035] A block copolymer that can be suitably used in the present invention may have at least one of the polymer block A and the polymer block B. Examples of such block copolymers include an AB diblock copolymer consisting of the polymer block A and the polymer block B, and an ABA triblock copolymer and a BAB triblock copolymer consisting of the polymer block A / the polymer block B / the polymer block A. The block copolymer may also be a multiblock copolymer having four or more polymer blocks, or a block copolymer having an ABC or ABCA structure that includes a polymer block C other than the polymer block A and the polymer block B. Among these, the block copolymer preferably has an AB structure, since the production steps are fewer than those of an ABC structure, reducing the possibility of contamination with various impurities and enabling the production of a highly pure product.

[0036] The mass ratio (A / B) of the polymer block A to the polymer block B in the block copolymer is preferably 50 / 50 to 99.9 / 0.1, more preferably 80 / 20 to 99 / 1, and even more preferably 90 / 10 to 98 / 2. The mass ratio (A / B) of the polymer block A to the polymer block B in the block copolymer may be 93 / 7 to 97 / 3. When the mass ratio is within this range, the polymer tends to adsorb to the oxide film and exhibit a protective effect. Furthermore, the polymer tends to be highly responsive to changes in polishing pressure, and when the oxide film is convex (high polishing pressure), the polymer does not adsorb and does not reduce the polishing rate. However, when polishing progresses and the nitride film is exposed, and the polishing target becomes concave (low polishing pressure), the polymer tends to adsorb to the oxide film interface and suppress over-polishing. These effects are believed to facilitate a good polished surface with reduced dishing without reducing the polishing rate.

[0037] When the block copolymer contains a polymer block C other than the polymer block A and the polymer block B, the total mass ratio of the polymer block A and the polymer block B to the entire block copolymer is preferably 90% by mass or more, more preferably 95% by mass or more. The total mass ratio of the polymer block A and the polymer block B to the entire block copolymer may be 98% by mass or more, or may be 99% by mass or more.

[0038] The chemical mechanical polishing additive provided by the present invention is an additive for chemical mechanical polishing containing a polymer (P), The polymer (P) contains structural units (A) derived from a vinyl monomer having a -(LO)nR group, and the total content of structural units derived from monomers containing one or more functional groups selected from the group consisting of carboxylic acid, phosphate, phosphonate, sulfate, sulfonate, and salts thereof is 0 to 0.6% by mass, and the polydispersity index (PDI) of the polymer (P), expressed as the weight-average molecular weight (Mw) / number-average molecular weight (Mn), is 2.0 or less. Therefore, the chemical mechanical polishing additive provided by the present invention may be a single component containing only the polymer (P), or may be a component containing the polymer (P) and other components (hereinafter also referred to as "other components") other than the polymer (P).

[0039] The chemical mechanical polishing additive provided by the present invention may contain a solvent as another component. Examples of the solvent include water, organic solvents, and mixed solvents of water and organic solvents. Among these, solvents capable of dissolving the polymer (P) are preferred, with water or mixed solvents of water and water-soluble organic solvents being more preferred, and water being particularly preferred. Examples of organic solvents used together 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; amide-based solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; and nitrile-based solvents such as acetonitrile. The organic solvents may be used alone or in combination.

[0040] When the chemical mechanical polishing additive provided by the present invention contains the polymer (P) and a solvent, the content of the polymer (P) is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on the total mass of the polymer (P) and the solvent, from the viewpoint of ensuring sufficient contact between the surface of the polishing object and the polishing pad and the polymer (P). Furthermore, the upper limit of the content of the polymer (P) is preferably 70% by mass, more preferably 60% by mass, and even more preferably 50% by mass, based on the total mass of the polymer (P) and the solvent, from the viewpoint of preventing deterioration in handleability due to excessive viscosity. A preferred range of the content of the polymer (P) can be expressed by any combination of these lower and upper limits. For example, the preferred range of the content of the polymer (P) may be 1% by mass or more to 70% by mass or less, 5% by mass or more to 60% by mass or less, or 10% by mass or more to 50% by mass or less, based on the total mass of the polymer (P) and the solvent.

[0041] <Method for producing polymer for polishing liquid additive> The method for producing the polymer for polishing liquid additives, i.e., the polymer (P) that can be suitably used in the present invention, is not particularly limited as long as it does not impair the effects of the present invention. For example, the polymer (P) can be produced by polymerizing the above-mentioned monomers using a known radical polymerization method such as solution polymerization or bulk polymerization. In the case of solution polymerization, for example, the target polymer can be obtained by charging a solvent and monomers into a reactor, adding a polymerization initiator, and polymerizing by heating.

[0042] Alternatively, a vinyl polymer having functional groups reactive with alcohols or amino groups, such as carboxyl groups, acid anhydride groups, or epoxy groups, such as poly(meth)acrylic acid or a polymer containing an acid anhydride structure or epoxy groups, is first produced by a known method. Next, the resulting polymer may be subjected to an esterification reaction, amidation reaction, etherification reaction, or amination reaction under known conditions in the presence of an acidic catalyst, a basic catalyst, a dehydration condensation agent, or the like, to produce the polymer (P). Furthermore, a known capping reaction, such as a methyl esterification reaction, may be performed to adjust the content of acidic functional groups.

[0043] The polymer (P) produced as described above may be purified by a known polymer purification method such as a reprecipitation method or a method using a porous material, so that the polydispersity index (PDI), which is expressed as weight average molecular weight (Mw) / number average molecular weight (Mn), is 2.0 or less.

[0044] Suitable methods for producing the polymer (P) include various controlled polymerization methods such as living radical polymerization and living anionic polymerization. Among these, living radical polymerization is preferred because it allows for high control of the polydispersity index (PDI), can produce a polymer with excellent abrasive grain dispersion stability, is easy to operate, and can be applied to a wide range of monomers. When using living radical polymerization, the polymerization method is not particularly limited, and polymerization can be carried out in various modes such as bulk polymerization, solution polymerization, emulsion polymerization, miniemulsion polymerization, and suspension polymerization.

[0045] For example, when the polymer (P) is produced by solution polymerization using a living radical polymerization method, a solvent and monomers are charged into a reactor, a radical polymerization initiator is added, and polymerization is preferably carried out by heating to obtain the target polymer (P). In the polymerization, any process such as a batch process, a semi-batch process, a dry continuous polymerization process, or a continuous stirred tank process (CSTR) may be used.

[0046] In producing the polymer (P), a living radical polymerization method utilizing a known polymerization mechanism can be employed. Specific examples of the living radical polymerization method include a living radical polymerization method based on an exchange chain mechanism, a living radical polymerization method based on a bond-dissociation mechanism, and a living radical polymerization method based on an atom transfer mechanism. Specific examples of these include living radical polymerizations based on an exchange chain mechanism, such as 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); living radical polymerizations based on a bond-dissociation mechanism, such as the nitroxy radical method (NMP); and living radical polymerizations based on an atom transfer mechanism, such as atom transfer radical polymerization (ATRP). Among these, living radical polymerizations based on an exchange chain mechanism are preferred because they can be applied to a wide range of vinyl monomers and have excellent polymerization controllability. The RAFT method or the NMP method is preferred in that contamination of the polishing object due to the inclusion of metal or semi-metallic compounds can be avoided, and the RAFT method is particularly preferred in that synthesis is easy in an aqueous system that does not require high temperatures.

[0047] In the RAFT method, polymerization proceeds via a reversible chain transfer reaction in the presence of a polymerization control agent (RAFT agent) and a radical polymerization initiator. Various known RAFT agents can be used, such as dithioester compounds, xanthate compounds, trithiocarbonate compounds, and dithiocarbamate compounds. Among these, trithiocarbonate compounds and dithiocarbamate compounds are preferred because they can produce polymers with a smaller molecular weight dispersity. Furthermore, the RAFT agent may be a monofunctional compound having only one active site, or a multifunctional compound having two or more active sites. The amount of the RAFT agent used is adjusted appropriately depending on the type of monomer and RAFT agent used, etc.

[0048] As the radical polymerization initiator used in polymerization by the RAFT method, known radical polymerization initiators such as azo compounds, organic peroxides, persulfates, etc. Among these, azo compounds are preferred because they are easy to handle safely and are less likely to cause side reactions during radical polymerization. Specific examples of azo compounds include 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis[N-(2-propenyl)-2-methylpropionamide], 2,2'-azobis(N-butyl-2-methylpropionamide), etc. These radical polymerization initiators may be used alone, or two or more radical polymerization initiators may be used in combination.

[0049] The amount of radical polymerization initiator used is not particularly limited, but from the viewpoint of obtaining a polymer with a smaller molecular weight dispersity, it is preferably 0.5 mol or less, more preferably 0.2 mol or less, per mol of RAFT agent. Furthermore, from the viewpoint of stably carrying out the polymerization reaction, the lower limit of the amount of radical polymerization initiator used is preferably 0.01 mol, more preferably 0.05 mol, per mol of RAFT agent. The amount of radical polymerization initiator used per mol of RAFT agent is preferably 0.01 to 0.5 mol, more preferably 0.05 to 0.2 mol.

[0050] When a solvent is used in living radical polymerization, examples of the polymerization solvent 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, alcohol, water, etc. These polymerization solvents may be used alone, or two or more of them may be used in combination.

[0051] In the polymerization reaction 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 because it allows the polymerization reaction to proceed smoothly, while a reaction temperature of 100°C or lower is preferred because it can suppress side reactions and alleviate restrictions on the initiators and solvents that can be used. The reaction time can be appropriately set depending on the monomers used, but is preferably 1 hour to 48 hours, more preferably 3 hours to 24 hours. The polymerization may be carried out in the presence of a chain transfer agent (e.g., an alkylthiol compound having 2 to 20 carbon atoms) as needed. In the production process, particularly when using monomers having acidic groups, if there is a concern about metal contamination due to corrosion of the reactor, it is preferable to produce the polymer using equipment whose surfaces are coated with a fluororesin or the like. In this case, it is preferable to use corrosion-resistant resin containers for storing the products. When a resin container is used, the container is preferably made of a material that prevents metal contamination due to dissolution of filler or the like.

[0052] ≪Polishing liquid composition≫ The polishing composition provided by the present invention contains at least the polymer (P) and abrasive grains, which may be at least one type of particle selected from the group consisting of known inorganic particles, organic particles, and organic-inorganic composite particles.

[0053] Specific examples of inorganic particles include cerium oxide (ceria), fumed silica, fumed alumina, fumed titania, colloidal silica, etc., and specific examples of organic particles include (meth)acrylic copolymers such as polymethyl methacrylate, polystyrene and polystyrene copolymers, polyacetal, polyamide, polycarbonate, polyolefin and polyolefin copolymers, phenoxy resin, etc. The organic-inorganic composite particles may be those in which the functional groups of the organic component and the functional groups of the inorganic component are chemically bonded, or those bonded or composited to an extent that they do not decompose under the conditions used as a polishing composition. Among these, cerium oxide and / or silica are preferred because they have lower hardness than alumina, etc., and have the advantage of being able to suppress the occurrence of defects on the polishing surface. Cerium oxide is particularly preferred because it can polish the polishing surface at a higher polishing rate than silica, alumina, etc.

[0054] The average particle size of the abrasive grains is not particularly limited, but is generally 1 nm to 500 nm. From the viewpoint of ensuring a high polishing rate, the average particle size of the abrasive grains is preferably 2 nm or more, more preferably 3 nm or more. From the viewpoint of suppressing the occurrence of scratches on the surface of the object to be polished, the upper limit of the average particle size of the abrasive grains is preferably 300 nm, more preferably 100 nm. In this specification, the average particle size of the abrasive grains is determined based on the specific surface area (m 2 The primary particle size is calculated using the formula (1 / g).

[0055] The content of the abrasive grains in the polishing composition is preferably 1% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of achieving a high polishing rate. The upper limit of the content of the abrasive grains is preferably 50% by mass, more preferably 45% by mass, and even more preferably 40% by mass, from the viewpoint of improving the smoothness of the object to be polished. A preferred range of the content of the abrasive grains can be expressed by any combination of these lower and upper limits. For example, the preferred range of the content of the abrasive grains may be 1% by mass or more to 50% by mass, 10% by mass or more to 45% by mass or less, or 15% by mass or more to 40% by mass or less.

[0056] The polishing composition may contain a solvent. The solvent is preferably an aqueous solvent. Examples of aqueous solvents include water and mixed solvents of water and other solvents. The other solvents are preferably solvents that are compatible with water, such as alcohols such as ethanol. The polishing composition may further contain known additives such as polishing accelerators, pH adjusters, surfactants, chelating agents, and anticorrosive agents, as long as the effects of the present invention are not impaired.

[0057] The content of the polymer (P) is preferably an amount such that the solids concentration of the polymer (P) is 0.001% by mass or more, more preferably 1% by mass or more, relative to the total amount of the polishing liquid composition. The upper limit of the content of the polymer (P) is preferably an amount such that the solids concentration of the polymer (P) is 10% by mass or more, more preferably 5% by mass, relative to the total amount of the polishing liquid composition. A preferred range of the content of the polymer (P) can be expressed by any combination of these lower and upper limits. For example, a preferred range of the content of the polymer (P) may be an amount such that the solids concentration of the polymer (P) is 0.001% by mass or more and 10% by mass or less, or 1% by mass or more and 5% by mass or less, relative to the total amount of the polishing liquid composition.

[0058] The polishing composition is usually prepared as a slurry mixture by mixing the components by a known method. The viscosity of the polishing composition at 25°C can be appropriately selected depending on the object to be polished, the shear rate during polishing, etc., but is preferably in the range of 0.1 to 10 mPa·s, more preferably 0.5 to 5 mPa·s.

[0059] Since the polishing composition contains the polymer (P) as an additive, the polishing rate for the convex portions (oxide film) on the uneven surface to be polished is sufficiently high, and dishing can be significantly reduced. Therefore, the polishing composition provided by the present invention is suitable for use in planarizing the surface of at least one of an insulating film and a metal wiring in the manufacturing process of a semiconductor device, specifically, for example, when used as a polishing liquid for planarizing an oxide film (such as a silicon oxide film) during shallow trench isolation (STI) formation, planarizing the surface of metal wiring made of copper, copper alloy, aluminum alloy, etc., or planarizing the surface of an interlayer insulating film (oxide film), as it reduces the occurrence of defects and enables the production of insulating films and metal wiring with excellent surface smoothness. [Example]

[0060] The present invention will be specifically described below based on examples. However, the present invention is not limited to these examples. In the following, "parts" and "%" mean parts by mass and % by mass unless otherwise specified. The analytical methods and production methods of the polymers used in the examples and comparative examples are described below.

[0061] <Molecular weight measurement> Using a gel permeation chromatograph (model HLC-8220, manufactured by Tosoh Corporation), the polystyrene-equivalent number average molecular weight (Mn) and weight average molecular weight (Mw) were obtained under the following conditions. The polydispersity index (PDI), i.e., the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) (Mw / Mn), was calculated from the obtained values. Measurement conditions Column: Tosoh TSKgel SuperMultiporeHxL-M x 4 Column temperature: 40℃ Eluent: tetrahydrofuran Detector: RI Flow rate: 0.6mL / min

[0062] <Mass composition ratio of polymer> The mass composition ratio of the obtained polymer was calculated based on the reaction rate of the monomer calculated by 1H-NMR measurement or gas chromatography (GC). The 1H-NMR measurement was performed using an Ascend™400 nuclear magnetic resonance measurement device manufactured by BRUKER at 25°C using tetramethylsilane as a standard substance and deuterated chloroform as a solvent. The GC measurements were performed using an Agilent 7820A (Agilent Technologies) as the device, a VARIAN CP-SIL 5CB (30 m x 0.32 mm, df = 3.0 μm) column, nitrogen as the carrier gas, and FID for detection.

[0063] 1. Polymer synthesis <Synthesis Example 1> A 1 L four-necked eggplant-shaped flask equipped with a stirrer, thermometer, and nitrogen inlet tube was charged with 150 g of purified water, 300 g of methoxypolyethylene glycol monoacrylate (NOF Corp., hereafter referred to as "AME-400"), 0.48 g of 4,4'-azobis(4-cyanovaleric acid) (Fujifilm Wako Pure Chemical Industries, Ltd., hereafter referred to as "V-501"), and 26.8 g of 3-((((1-carboxyethyl)thio)carbonothioyl)thio)propanoic acid (BORON MOLECULAR, hereafter referred to as "BM1429") as a RAFT agent. After thorough degassing with nitrogen bubbling, the flask was heated in a thermostatic bath at 70 °C to initiate polymerization. After 3 h, the flask was water-cooled to terminate the polymerization. The conversion of AME-400 at the time of termination was determined by 1H-NMR measurement to be 95%. Next, 15.6 g of ethyl acrylate (hereinafter also referred to as "EA") was added to the flask, which was thoroughly degassed by bubbling nitrogen. The flask was then heated in a thermostatic chamber at 70°C to initiate polymerization. After 3 hours, the polymerization was terminated by water-cooling the flask. The conversion of EA at the time of termination of polymerization was determined by GC measurement to be 99%. The molecular weight of the water-soluble block copolymer obtained above (referred to as "Polymer A") was determined by GPC measurement to be Mn 3,030, Mw 3,430, and PDI 1.1.

[0064] <Synthesis Examples 2 to 22, 26 to 35, Comparative Synthesis Examples 2 and 6> Water-soluble block copolymers (polymers B to V, Z to i, m, and q) were obtained by the same procedure as in Synthesis Example 1, except that the raw materials used were changed as shown in Tables 1 to 5. The molecular weights of polymers B to V, Z to i, m, and q were determined by GPC measurement, and the results are shown in Tables 1 to 5.

[0065] <Synthesis Example 23> A 1 L four-necked eggplant flask equipped with a stirrer, thermometer, and nitrogen inlet tube was charged with 150 g of purified water, 300 g of AME-400, 0.48 g of V-501, and 25.4 g of BM1429. After thorough degassing with nitrogen bubbling, the flask was heated in a thermostatic chamber at 70 °C to initiate polymerization. After 5 hours, the polymerization was terminated by water cooling. The conversion of AME-400 at the time of termination was determined by 1H-NMR measurement to be 99%. The molecular weight of the resulting water-soluble polymer (referred to as "Polymer W") was determined by GPC analysis to be Mn 3,000, Mw 3,390, and PDI 1.1.

[0066] <Synthesis Examples 24-25> Water-soluble polymers (polymers X and Y) were obtained in the same manner as in Synthesis Example 23, except that the raw materials used were changed as shown in Table 3. The molecular weights of polymers X and Y were determined by GPC measurement, and the results are shown in Table 3.

[0067] <Synthesis Example 36> A 1 L four-necked eggplant flask equipped with a stirrer, thermometer, and nitrogen inlet tube was charged with 150 g of purified water, 300 g of AME-400, 0.48 g of V-501, and 26.8 g of BM1429. After thorough degassing with nitrogen bubbling, the flask was heated in a thermostatic bath at 70 °C to initiate polymerization. After 3 hours, the polymerization was terminated by water-cooling the flask. The conversion of AME-400 was determined to be 95% by 1H-NMR measurement. Next, 7.8 g of EA was added to the flask, and after thorough degassing with nitrogen bubbling, the flask was heated in a thermostatic bath at 70 °C to initiate polymerization. After 3 hours, the polymerization was terminated by water-cooling the flask. The conversion of EA was determined to be 95% by GC measurement. Next, 7.8 g of t-butylacrylamide (hereinafter also referred to as "TBAM") was added to the flask, and after thorough degassing by nitrogen bubbling, the flask was heated in a thermostatic bath at 70°C to initiate polymerization. After 3 hours, the polymerization was terminated by water-cooling the flask. The conversion of TBAM was determined by GC measurement to be 90%. The molecular weight of the resulting water-soluble block copolymer (referred to as "polymer j") was determined by GPC measurement to be Mn 3,120, Mw 3,490, and PDI 1.1.

[0068] <Synthesis Example 37> Water-soluble polymer k was obtained by the same procedure as in Synthesis Example 36, except that the raw materials used were changed as shown in Table 4. The molecular weight of polymer k was determined by GPC measurement, and the results are shown in Table 4.

[0069] <Comparative Synthesis Example 1> Water-soluble polymer 1 was obtained by the same procedure as in Synthesis Example 23, except that the raw materials used were changed as shown in Table 5. The molecular weight of polymer 1 was determined by GPC measurement, and the results are shown in Table 5.

[0070] <Comparative Synthesis Example 3> A 1 L four-necked eggplant flask equipped with a stirrer, thermometer, and nitrogen inlet tube was charged with 100 g of acetonitrile and stirred at 75°C. Next, an initiator solution consisting of 0.10 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (Fujifilm Wako Pure Chemical Industries, Ltd., hereafter referred to as "V-65") dissolved in 7.2 g of acetonitrile was added to the flask. Then, 432 g of AME-400 and a chain transfer agent solution consisting of 50 g of 3-methoxybutyl 3-mercaptopropionate (hereafter referred to as "MPMB") dissolved in 64 g of acetonitrile were each fed into the flask over 3 hours. Simultaneously with the chain transfer agent solution, an initiator solution consisting of 0.40 g of V-65 dissolved in 40 g of acetonitrile was fed into the flask over 5 hours. After the initiator solution was added, the contents of the flask were heated and stirred for an additional 1.5 hours. The polymerization was then terminated by water-cooling the flask. The solvent was then removed from the contents of the flask using an evaporator. The conversion of AME-400 at the time of polymerization termination was determined by 1H-NMR measurement to be 99%. The molecular weight of the resulting water-soluble polymer (referred to as "polymer n") was determined by GPC measurement to be Mn 2,600, Mw 5,720, and PDI 2.2.

[0071] <Comparative Synthesis Examples 4-5> Water-soluble copolymers (polymers o to p) were obtained in the same manner as in Comparative Synthesis Example 3, except that the raw materials used were changed as shown in Table 5. The molecular weights of polymers o to p were determined by GPC measurement, and the results are shown in Table 5.

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] [Table 4]

[0076] [Table 5]

[0077] Details of the compounds shown in Tables 1 to 11 are as follows. AME-400: Methoxypolyethylene glycol monoacrylate (n=9) (NOF Corporation, trade name: Blenmar AME-400) PME-400: Methoxypolyethylene glycol monomethacrylate (n=9) (NOF Corporation, trade name: Blenmar PME-400) MTG-A: Methoxytriethylene glycol acrylate (manufactured by Kyoeisha Chemical, product name: Light Acrylate MTG-A) AM-230G: methoxypolyethylene glycol acrylate (n=23) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name: NK Ester AM-230G) AE-400: Polyalkylene glycol monoacrylate (n=10) (NOF Corporation, product name: Blenmar AE-400) EA: Ethyl acrylate NIPAM: N-isopropylacrylamide ACMO: N-acryloylmorpholine AA: acrylic acid V-501: 4,4'-Azobis(4-cyanovaleric acid) (Fujifilm Wako Pure Chemical Industries, Ltd.) V-65: 2,2'-azobis(2,4-dimethylvaleronitrile) (Fujifilm Wako Pure Chemical Industries, Ltd.) BM1429: 3-((((1-carboxyethyl)thio)carbonothioyl)thio)propanoic acid (BORON MOLECULAR) MPMB: 3-Methoxybutyl 3-mercaptopropionate BA: n-butyl acrylate MA: methyl acrylate HexA: n-hexyl acrylate TBAM: N-tert-butylacrylamide DMAA: N,N-dimethylacrylamide DEAA: N,N-diethylacrylamide HEAA: N-(2-hydroxyethyl)acrylamide DPM-A: Methoxydipropylene glycol acrylate (manufactured by Kyoeisha Chemical, product name: Light Acrylate DPM-A) HEA: 2-hydroxyethyl acrylate XL-80: Polyoxyalkylene branched decyl ether (surfactant manufactured by Daiichi Kogyo Seiyaku, trade name: Noigen (registered trademark) XL-80)

[0078] 2. Measurement and Evaluation < Reference example 1 > 500 parts of a polymer aqueous solution was prepared containing 0.5% by mass of polymer A. Next, the previously prepared polymer aqueous solution was added to 500 parts of an aqueous dispersion of colloidal ceria (manufactured by NYACOL, trade name: NYACOL 80 / 10, particle concentration 10%, average particle diameter 80 nm) while stirring, to obtain a polishing liquid composition.

[0079] < Reference Examples 2 to 5, 10 to 12, 17 to 20, 23 to 24, 26, 28, 30, 32, Examples 6 to 9, 13 to 16, 21 to 22, 25, 27, 29, 31, 33 to 37 , Comparative Examples 3 to 9> Except for changing polymer A to the polymer or surfactant shown in Tables 6 to 11, Reference example 1 The same procedure as in the above was carried out to obtain a polishing composition.

[0080] < Reference example 38 > 500 parts of a polymer aqueous solution containing polymer A at a solids concentration of 0.5% by mass was prepared. Next, while stirring 500 parts of an aqueous dispersion of colloidal silica (manufactured by Fuso Chemical Co., Ltd., product name: Quattron PL-7, particle concentration 23%, average particle diameter 75 nm), the previously prepared polymer aqueous solution was added, and the pH was adjusted to 9 with 28% aqueous ammonia to obtain a polishing composition. Note that "Quattron" is a registered trademark of Fuso Chemical Co., Ltd.

[0081] Example 39 Except for changing the polymer A to the polymer shown in Table 10 Reference example 38 The same operation was performed to obtain a polishing liquid composition.

[0082] <Comparative Example 1> While stirring 500 parts of an aqueous dispersion of colloidal ceria (manufactured by NYACOL, trade name: NYACOL 80 / 10, particle concentration 10%, average particle diameter 80 nm), 500 parts of pure water was added to obtain a polishing liquid composition.

[0083] <Comparative Example 2> While stirring 500 parts of an aqueous dispersion of colloidal silica (manufactured by Fuso Chemical Industry Co., Ltd., trade name: Quartron PL-7, particle concentration 23%, average particle diameter 75 nm), 500 parts of pure water was added, and then the pH was adjusted to 9 with 28% aqueous ammonia to obtain a polishing liquid composition.

[0084] Using each polishing liquid composition prepared by the above method, a polishing test was carried out under the following conditions. <Polishing Conditions> Polishing tester: manufactured by Kemet Japan, trade name: MAT-ARW-CMS Polishing pad: manufactured by Rodel Nitta, trade name: IC-1000 / Sub400 Platen rotation speed: 60 rpm Carrier rotation speed: 61 rpm Polishing liquid supply rate: 150 g / min Polishing pressure: 1 psi, 3 psi or 5 psi

[0085] <l <RR Measurement / Evaluation Method> A blanket wafer with 1.4 μm of silicon oxide formed by CVD on a 4-inch silicon substrate was used as the workpiece to be polished, polished for 1 minute under the above polishing conditions, and the polishing rate (RR) (unit: nm / min) was determined from the difference in the remaining film thickness before and after polishing. The remaining film thickness was measured using an optical interference film thickness meter. Regarding the RR of each polishing liquid composition, the RR of the polishing liquid compositions of Examples 1 to 37 and Comparative Examples 3 to 9 was evaluated as the ratio to the RR of the polishing liquid composition of Comparative Example 1, and the RR of the polishing liquid compositions of Examples 38 to 39 was evaluated as the ratio to the RR of the polishing liquid composition of Comparative Example 2 (both at 3 psi). The evaluation criteria for RR were as follows. (Let the RR of Comparative Examples 1 to 2 be RRa, and the RR of the polishing liquid compositions of Examples 1 to 37 and Comparative Examples 3 to 9 be RRb, and the calculated values of RRb / RRa are shown in Tables 6 to 11.) Note that for the polishing liquid compositions of Comparative Examples 1 to 2, RRb / RRa = 1.00. Subsequently, regarding the dishing reduction performance, based on the ratio of the RR at 3 psi (RR3) to the RR at 1 psi (RR1) (RR3 / RR1), and the ratio of the RR at 5 psi (RR5) to RR1 (RR5 / RR1), the following criteria were used for evaluation. When both criteria C of RR and dishing reduction performance were satisfied, it was considered qualified. <Evaluation Criteria for RR> A: RRb / RRa ≥ 0.85 B: 0.85 > RRb / RRa ≥ 0.70 C: 0.70 > RRb / RRa ≥ 0.50 D: RRb / RRa < 0.50 <Evaluation Criteria for Dishing Reduction Performance> A: RR3 / RR1 ≥ 4.0 and RR5 / RR1 ≥ 7.0 B: 4.0 > RR3 / RR1 > 3.5, or 7.0 > RR5 / RR1 > 6.5 C: 3.5 ≥ RR3 / RR1 > 3.0, or 6.5 ≥ RR5 / RR1 > 5.2 D: RR3 / RR1 ≤ 3.0 and RR5 / RR1 ≤ 5.2

[0086] <Evaluation Results> In the polishing of the blanket wafer using the polishing liquid composition of each example, the RR (RR1, RR3, RR5) at each polishing pressure, the RRb / RRa value which is the evaluation index of RR, and the values of RR3 / RR1 and RR5 / RR1 which are the evaluation indexes of dishing reduction performance are shown in Tables 6 to 11. A polishing composition that exhibits suppressed RR at low polishing pressures and high RR at high polishing pressures can produce a favorable polished surface with reduced dishing on a patterned wafer without lowering RR. For each of the polishing liquid compositions of the Examples, RR was suppressed at low polishing pressures and showed high RR at high polishing pressures, resulting in large RR3 / RR1 and RR5 / RR1. Furthermore, because the decrease in RR3 was small, RRb / RRa also increased. In contrast, in the case of Comparative Examples 1 and 2, in which no additive was added, RR was nearly proportional to the polishing pressure. In Comparative Examples 4, 5, and 9, RR was significantly suppressed at all polishing pressures, and neither RR nor dishing reduction performance met the pass criteria. In Comparative Examples 3 and 6 to 8, relatively high RR was shown at each polishing pressure, but RR was not significantly suppressed at low polishing pressures, resulting in insufficient dishing reduction performance.

[0087] [Table 6]

[0088] [Table 7]

[0089] [Table 8]

[0090] [Table 9]

[0091] [Table 10]

[0092] [Table 11]

Claims

1. An additive containing a polymer (P) and used in chemical mechanical polishing in a manufacturing process of a semiconductor device, The polymer (P) contains structural units (A) derived from a vinyl monomer having a -(LO)n-R group and structural units (B) derived from a (meth)acrylamide vinyl monomer (excluding the vinyl monomer having a -(LO)n-R group), and the total content of structural units derived from monomers containing one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof is 0 to 0.6 mass %, and the polymer (P) has a polydispersity index (PDI) expressed as weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.0 or less. (wherein L is an alkylene group having 4 or less carbon atoms, n is an integer from 3 to 150, and R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms.)

2. The additive according to claim 1, wherein the number average molecular weight (Mn) of the polymer (P) is 1,000 to 100,000.

3. The structural unit (B) has an SP value calculated by the Fedors estimation method of 17 to 25 (J / cm 3 ) 0.5 The additive according to claim 1, wherein the structural unit is derived from a monomer represented by the formula:

4. The additive according to claim 1 , wherein the polymer (P) is a block polymer.

5. The polymer (P) contains a polymer block A and a polymer block B, The polymer block A has the structural unit (A), The additive according to claim 4 , wherein the polymer block B has the structural unit (B).

6. The additive according to claim 5, wherein the ratio (A / B) of the polymer block A to the polymer block B in the polymer (P) is 50 / 50 to 99.9 / 0.1 by mass.

7. 7. A polishing composition for chemical mechanical polishing used for planarizing the surface of at least one of an insulating layer and a wiring layer, the polishing composition comprising the additive according to claim 1 and cerium oxide and / or silica.

8. A method for producing an additive for a chemical mechanical polishing solution containing a polymer and used in chemical mechanical polishing in a manufacturing process of a semiconductor device, comprising: The polymer contains structural units derived from a vinyl monomer having a -(LO)n-R group and structural units derived from a (meth)acrylamide-type vinyl monomer (excluding the vinyl monomer having the -(LO)n-R group), and the content of structural units derived from monomers containing one or more functional groups selected from the group consisting of a carboxylic acid group, a phosphoric acid group, a phosphonic acid group, a sulfuric acid group, a sulfonic acid group, and salts thereof is 0 to 0.6 mass% in total, and the polymer has a polydispersity index (PDI) expressed as weight average molecular weight (Mw) / number average molecular weight (Mn) of 2.0 or less, the method comprising the step of producing the polymer by a living radical polymerization method. (wherein L is an alkylene group having 4 or less carbon atoms, n is an integer from 3 to 150, and R is a hydrogen atom or a monovalent hydrocarbon group having 1 to 4 carbon atoms.)

Images