Dispersion liquid containing silica particles and basic aluminum salt aqueous solution, and polishing composition

Abstract

Provided are: a silica particle-containing dispersion liquid capable of polishing a resin or the like at a high polishing speed and having excellent storage stability even at a high concentration; and a polishing composition containing said dispersion liquid.　The dispersion liquid contains silica particles and a basic aluminum salt aqueous solution, wherein at least a portion of the surface of the silica particles is coated with an aluminum-containing compound, and the number of aluminum atoms of the free aluminum component in the dispersion liquid is 1-60 µmol / m2 with respect to the surface area of the silica particles.

Description

Dispersion containing silica particles and aqueous basic aluminum salt solution, and polishing composition

[0001] The present invention relates to a dispersion containing silica particles and an aqueous solution of a basic aluminum salt, in which at least a portion of the surface of the silica particles is coated with an aluminum-containing compound, and a polishing composition containing the dispersion.

[0002] New microfabrication techniques have been developed to accompany the increasing integration and performance of semiconductor integrated circuits (hereinafter referred to as "LSIs"). Chemical mechanical polishing (hereinafter sometimes referred to as "CMP") is one such technique, and is a technique frequently used in the LSI manufacturing process.

[0003] Resins are used as insulating materials in semiconductor packages. CMP has begun to be applied to LSI packaging processes, and the need for resin polishing is increasing. For example, in the manufacturing process of semiconductor devices, a method has been proposed in which a polished object containing a polyimide film as a resin is chemically mechanically polished using a polishing composition containing at least one abrasive having a modified Mohs hardness of 13 or higher (see Patent Document 1). However, simply using hard abrasives can cause problems such as polishing scratches and roughness of the polished surface.

[0004] Also proposed is a chemical mechanical polishing method using silica with an aluminum compound attached to its surface as an abrasive (see Patent Documents 2 and 3). Dispersions used in such CMP are often produced and stored at high concentrations for cost and transportation convenience, and are often diluted immediately before use. However, since such dispersions are generally dispersions of particles obtained by mixing anionic silica particles and cationic aluminum compounds, particle aggregation tends to occur, making it difficult to achieve both storage stability and high concentration.

[0005] Japanese Patent Application Laid-Open No. 2010-135472 International Publication No. 2020 / 196542 Special Publication No. 2022-517875

[0006] The present invention aims to provide a dispersion containing silica particles that can polish resins and the like at a high polishing rate and has excellent storage stability even at high concentrations, and a polishing composition containing the dispersion.

[0007] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by using a dispersion containing silica particles and an aqueous solution of a basic aluminum salt, in which at least a portion of the surface of the silica particles is coated with an aluminum-containing compound, and the number of aluminum atoms in the free aluminum component in the dispersion is within a specific range relative to the surface area of ​​the silica particles, and have completed the present invention.

[0008] That is, the gist of the present invention is as follows: [1] A dispersion containing silica particles and an aqueous solution of a basic aluminum salt, wherein at least a portion of the surface of the silica particles is coated with an aluminum-containing compound, and the number of aluminum atoms of the free aluminum component in the dispersion is 1 to 60 μmol / m with respect to the surface area of ​​the silica particles. ２ [2] The dispersion according to [1], wherein the silica particles in the dispersion are present in an amount of 8 to 40 mass % based on the total mass of the dispersion, in terms of the mass of silica solid content. [3] The number of aluminum atoms in all aluminum components in the dispersion is 6 to 65 μmol / m with respect to the surface area of ​​the silica particles. ２ [4] The dispersion according to any one of [1] to [3], wherein the basic aluminum salt contains basic aluminum acetate. [5] The dispersion according to any one of [1] to [3], wherein the basic aluminum acetate is Al(OH) Ｘ (CH ３ COO) ３－Ｘ(wherein X represents a real number of 0.9 to 2.7). [6] The dispersion according to any one of [1] to [5], wherein the particles contained in the dispersion have a zeta potential of 30 to 65 mV. [7] The dispersion according to any one of [1] to [6], wherein the silica particles have an average primary particle diameter of 10 to 500 nm as measured by a nitrogen gas adsorption method. [8] A polishing composition comprising the dispersion according to any one of [1] to [7]. [9] The polishing composition according to [8], wherein the polishing composition is used for polishing a resin.

[10] The polishing composition according to [9], wherein the resin is a polyimide.

[0009] According to the present invention, it is possible to provide a dispersion containing silica particles that can polish resins and the like at a high polishing rate and has excellent storage stability even at high concentrations, and a polishing composition containing the dispersion.

[0010] Preferred embodiments of the present invention will be described below. However, the following embodiments are merely examples for explaining the present invention, and the present invention is not limited to the following embodiments. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0011] [Dispersion] The dispersion of the present invention is a dispersion containing silica particles and a basic aluminum salt aqueous solution, wherein at least a portion of the surface of the silica particles is coated with an aluminum-containing compound, and the number of aluminum atoms of the free aluminum component in the dispersion is 1 to 60 μmol / m with respect to the surface area of ​​the silica particles. ２In this specification, silica particles at least a portion of whose surface is coated with an aluminum-containing compound may be referred to as "coated silica particles." The specific surface area of ​​the silica particles was measured according to the BET method. In the present invention, it is believed that the entire amount of the added basic aluminum salt does not coat the surface of the silica particles, and a portion of it becomes a free aluminum component, which contributes to improving stability. In addition, if there is an excess of free aluminum component, it is believed that the polishing action of the silica particles is physically inhibited, adversely affecting the polishing rate.

[0012] In the present invention, the quantitative determination of the free aluminum component can be obtained by measuring the amount of aluminum contained in the liquid from which silica particles have been removed by ICP emission spectrometry or a calcination method. The liquid from which silica particles have been removed can be a filtrate obtained by placing the dispersion in a centrifuge tube equipped with an ultrafiltration membrane and centrifuging it in a centrifuge. For example, an Amicon Ultra-15 10K (manufactured by Merck) can be used as the centrifuge tube equipped with an ultrafiltration membrane.

[0013] Considering the effects of the present invention, the number of aluminum atoms in the free aluminum component in the dispersion is 2 to 60 μmol / m with respect to the surface area of ​​the silica particles. ２ is preferred, and 3 to 45 μmol / m ２ More preferably, 4 to 30 μmol / m ２ Here, the "number of aluminum atoms of the free aluminum component / surface area of ​​the silica particles" (unit: μmol / m ２ ) can be calculated using the following formula: aluminum-equivalent concentration of free aluminum component [mass%] / 27×10 ６ / (specific surface area [m ２ / g] × silica particle concentration [mass%])

[0014] In the present invention, silica particles contained in an aqueous silica sol can be used as the silica particles. Aqueous silica sols can be obtained, for example, by cation-exchanging water glass to obtain activated silicic acid, which is then grown under heating, or by hydrolysis and dehydration condensation of an organosilicon compound. As such aqueous silica sols, for example, silica sol manufactured by Nissan Chemical Industries, Ltd. (trade name: Snowtex (registered trademark)) can be used. Typically, aqueous silica sols with a silica concentration of 10 to 40% by mass can be used. The particle diameter of the silica particles in the aqueous silica sol can be a primary particle diameter of 10 to 500 nm and a secondary particle diameter of 15 to 1000 nm.

[0015] The aqueous silica sol used in the present invention is preferably acidic or neutral, more preferably acidic. Acidic or neutral silica sol can be obtained by adding an acid to an alkaline silica sol or by exchanging hydrogen ions with cationic components in the alkaline silica sol using a hydrogen ion type cation exchange resin.

[0016] The dispersion of the present invention can be prepared by mixing an aqueous silica sol with an aqueous solution of a basic aluminum salt. Examples include a method in which the aqueous silica sol is added while stirring the aqueous silica sol, or a method in which the aqueous silica sol is added while stirring the aqueous solution of a basic aluminum salt. During the stirring, it is important that the stirring efficiency is high and that the shearing action of the stirring blades is strong; insufficient stirring efficiency and shearing action can lead to an increase in the secondary particle size of the silica particles and an increase in the viscosity of the dispersion. Furthermore, when adding the aqueous silica sol while stirring the aqueous solution of a basic aluminum salt, it is preferable to add the aqueous silica sol slowly; for example, it is preferable to add the entire amount over a period of about 1 to 10 hours. A fast addition rate can lead to an increase in the secondary particle size of the silica particles and an increase in the viscosity of the dispersion.

[0017] In the present invention, the silica particles in the dispersion are present in an amount of preferably 8 to 40 mass %, more preferably 9 to 30 mass %, even more preferably 10 to 25 mass %, and still more preferably 10 to 20 mass %, calculated as the silica solid content, based on the total mass of the dispersion.

[0018] In the present invention, the total aluminum content in the dispersion can be determined by measuring the amount of aluminum contained in a solution in which silica particles are dissolved by ICP atomic emission spectrometry. The solution in which silica particles are dissolved can be obtained by adding hydrofluoric acid to the dispersion and dissolving the silica particles by heating.

[0019] Considering the effects of the present invention, the number of aluminum atoms in the total aluminum component in the dispersion is 6 to 65 μmol / m with respect to the surface area of ​​the silica particles. ２ is preferred, and 8 to 65 μmol / m ２ More preferably, 9 to 50 μmol / m ２ More preferably, 9 to 35 μmol / m ２ Here, the "number of aluminum atoms in all aluminum components / surface area of ​​silica particles" (unit: μmol / m ２ ) can be calculated using the following formula: aluminum-equivalent concentration of all aluminum components [mass%] / 27×10 ６ / (specific surface area [m ２ / g] × silica particle concentration [mass %]) In the examples described later, the specific surface area is 45.5 m ２ / g or 32.9m ２ / g.

[0020] Specific examples of the basic aluminum salt include basic aluminum acetate, basic aluminum formate, basic aluminum lactate, basic aluminum chloride, and basic aluminum nitrate. Among these, basic aluminum acetate, basic aluminum formate, and basic aluminum lactate are preferred, and Al(OH) Ｘ (CH ３ COO) ３－Ｘ It is more preferable that the aluminum acetate solution contains basic aluminum acetate having the chemical composition: (wherein X is a real number of 0.9 to 2.7).

[0021] The basic aluminum salt aqueous solution can be prepared by a known method, for example, by using Al(OH) Ｘ (CH ３ COO)３－Ｘ An aqueous solution of basic aluminum acetate having excellent storage stability and represented by the chemical composition: (wherein X is a real number of 0.9 to 2.7) can be prepared by appropriately referring to JP-A-8-59230.

[0022] The pH of the dispersion of the present invention can be determined using the measurement method described below. In consideration of the effects of the present invention, it is preferable to adjust the pH to 3.0 to 7.0, preferably 3.5 to 6.0, and more preferably 4.0 to 5.5, for example, by adding an organic acid or an alkali component.

[0023] The zeta potential of the particles contained in the dispersion of the present invention can be determined using the measurement method described below, and in consideration of the effects of the present invention, it is preferably 30 to 65 mV, more preferably 35 to 60 mV, and even more preferably 40 to 60 mV. By setting the zeta potential to 30 mV or more, it is possible to suppress a decrease in the polishing rate and also to suppress a deterioration in dispersion stability during storage.

[0024] The average primary particle diameter of the silica particles or coated silica particles, as measured by nitrogen gas adsorption (BET) method as described below, is preferably 10 to 500 nm, more preferably 20 to 300 nm, even more preferably 30 to 200 nm, and even more preferably 40 to 120 nm. By setting the particle diameter to at least the above lower limit, a decrease in the polishing rate can be suppressed, and deterioration of dispersion stability during storage can also be suppressed. Furthermore, by setting the particle diameter to at most the above upper limit, deterioration of polishing quality, such as scratch defects and surface roughness, can be suppressed.

[0025] The average secondary particle diameter of the silica particles or coated silica particles is measured by dynamic light scattering (DLS) as described below, and is preferably 15 to 1000 nm, more preferably 30 to 600 nm, even more preferably 50 to 400 nm, and still more preferably 60 to 200 nm.

[0026] The dispersion of the present invention may contain at least one additive selected from the group consisting of alkaline components and acidic components.

[0027] Examples of the alkaline component include potassium hydroxide or potassium bicarbonate, or sodium hydroxide, ammonia, amines, primary ammonium hydroxide, secondary ammonium hydroxide, tertiary ammonium hydroxide, quaternary ammonium hydroxide, lithium carbonate, sodium carbonate, potassium carbonate, lithium bicarbonate, sodium bicarbonate, and mixtures thereof.

[0028] Examples of the acidic component include inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, phosphonic acid, and boric acid, and organic acids such as acetic acid, formic acid, lactic acid, tartaric acid, citric acid, malonic acid, gluconic acid, and glycine, and mixtures thereof.

[0029] The dispersion of the present invention may contain additives such as dispersants, surfactants, rust inhibitors, preservatives, bactericides, wetting agents, thickeners, and chelating agents, as long as the effects of the invention are not impaired.

[0030] [Polishing composition] The polishing composition of the present invention refers to the above-mentioned dispersion or a composition containing the dispersion. The polishing target of the polishing composition of the present invention is not limited, but can be used to polish, for example, resins such as polyimide. As an example, the polishing target of the polishing composition of the present invention can be exemplified by organic insulating films such as polyimide, epoxy, acrylic, polyimide, and polybenzoxazole; carbon-containing films such as spin-on carbon and amorphous carbon films; metal wiring such as copper, aluminum, and tungsten; and composite films in which these are present simultaneously.

[0031] The polishing composition of the present invention can be used to polish composite films in which resin and metal wiring coexist, and therefore can contain additives commonly used in polishing metal wiring, such as oxidizing agents and metal corrosion inhibitors.

[0032] Examples of the oxidizing agent include hydrogen peroxide, nitric acid, potassium periodate, hypochlorous acid, ozone water, etc. The oxidizing agent can be contained in an amount of 0.01 to 10% by mass relative to the silica particles.

[0033] Examples of metal corrosion inhibitors include triazole compounds, pyridine compounds, pyrazole compounds, pyrimidine compounds, imidazole compounds, guanidine compounds, thiazole compounds, tetrazole compounds, triazine compounds, and hexamethylenetetramine. Examples of triazole compounds include 1,2,3-triazole, 1,2,4-triazole, 3-amino-1H-1,2,4-triazole, benzotriazole (BTA), 1-hydroxybenzotriazole, 1-hydroxypropylbenzotriazole, 2,3-dicarboxypropylbenzotriazole, 4-hydroxybenzotriazole, 4-carboxy-1H-benzotriazole, 4-carboxy-1H-benzotriazole methyl ester (methyl 1H-benzotriazole-4-carboxylate), 4-carboxy-1H-benzotriazole butyl ester (butyl 1H-benzotriazole-4-carboxylate), 4-carboxy-1H-benzotriazole octyl ester (octyl 1H-benzotriazole-4-carboxylate), 5-hexylbenzotriazole, (1,2,3-benzotriazolyl-1-methyl) (1,2,4-triazole), (1-benzotriazolyl-1-methyl)(2-ethylhexyl)amine, tolyltriazole, naphthotriazole, bis[(1-benzotriazolyl)methyl]phosphonic acid, 3H-1,2,3-triazolo[4,5-b]pyridin-3-ol, 1H-1,2,3-triazolo[4,5-b]pyridine, 1-acetyl-1H-1,2,3-triazolo[4,5-b]pyridine, 3-hydroxypyridine, 1,2,4-triazolo[1,5-a]pyridine pyrimidine, 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine, 2-methyl-5,7-diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, 2-methylsulfanyl-5,7-diphenyl-[1,2,4]triazolo[1,5-a]pyrimidine, 2-methylsulfanyl-5,7-diphenyl-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine, and the like.Examples of the pyridine compound include pyridine, 8-hydroxyquinoline, prothionamide, 2-nitropyridin-3-ol, pyridoxamine, nicotinamide, iproniazid, isonicotinic acid, benzo[f]quinoline, 2,5-pyridinedicarboxylic acid, 4-styrylpyridine, anabasine, 4-nitropyridine-1-oxide, ethyl pyridine-3-acetate, quinoline, 2-ethylpyridine, quinolinic acid, arecoline, citrazinic acid, pyridine-3-methanol, 2-methyl-5-ethylpyridine, 2-fluoropyridine, pentafluoropyridine, 6-methylpyridin-3-ol, and ethyl pyridine-2-acetate. Examples of the pyrazole compound include pyrazole, 1-allyl-3,5-dimethylpyrazole, 3,5-di(2-pyridyl)pyrazole, 3,5-diisopropylpyrazole, 3,5-dimethyl-1-hydroxymethylpyrazole, 3,5-dimethyl-1-phenylpyrazole, 3,5-dimethylpyrazole, 3-amino-5-hydroxypyrazole, 4-methylpyrazole, N-methylpyrazole, and 3-aminopyrazole. Examples of the pyrimidine compound include pyrimidine, 1,3-diphenyl-pyrimidine-2,4,6-trione, 1,4,5,6-tetrahydropyrimidine, 2,4,5,6-tetraaminopyrimidine sulfate, 2,4,5-trihydroxypyrimidine, 2,4,6-triaminopyrimidine, 2,4,6-trichloropyrimidine, 2,4,6-trimethoxypyrimidine, 2,4,6-triphenylpyrimidine, 2,4-diamino-6-hydroxylpyrimidine, 2,4-diaminopyrimidine, 2-acetamidopyrimidine, 2-aminopyrimidine, and 4-aminopyrazolo[3,4-d]pyrimidine. Examples of the imidazole compound include imidazole, 1,1'-carbonylbis-1H-imidazole, 1,1'-oxalyldiimidazole, 1,2,4,5-tetramethylimidazole, 1,2-dimethyl-5-nitroimidazole, 1,2-dimethylimidazole, 1-(3-aminopropyl)imidazole, 1-butylimidazole, 1-ethylimidazole, 1-methylimidazole, and benzimidazole.Examples of guanidine compounds include guanidine, 1,1,3,3-tetramethylguanidine, 1,2,3-triphenylguanidine, 1,3-di-o-tolylguanidine, and 1,3-diphenylguanidine. Examples of thiazole compounds include thiazole, 2-mercaptobenzothiazole, and 2,4-dimethylthiazole. Examples of tetrazole compounds include tetrazole, 5-methyltetrazole, 5-amino-1H-tetrazole, and 1-(2-dimethylaminoethyl)-5-mercaptotetrazole. Examples of triazine compounds include triazine and 3,4-dihydro-3-hydroxy-4-oxo-1,2,4-triazine. The metal corrosion inhibitor can be added in a ratio of 0.0001 to 10% by mass relative to the silica particles.

[0034] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples in any way.

[0035] <1. Methods for Measuring Particle Size, pH, and Zeta Potential> [Measurement of Specific Surface Area by BET Method] After removing as many cations and anions as possible from the alkaline silica sol using a hydrogen-type strongly acidic cation exchange resin, Amberlite (registered trademark) IR-120B, and a hydroxyl-type strongly basic anion exchange resin, Amberlite (registered trademark) IRA-410, the sol was dried by heating at 290°C for 1 hour in an air atmosphere using an electric furnace (DX302, manufactured by Yamato Scientific Co., Ltd.). The dried powder was thoroughly ground in an agate mortar to obtain a dried powder sample, which was used as a measurement sample. The specific surface area of ​​the measurement sample was measured by the nitrogen adsorption method (BET method) using a specific surface area measurement device, Monosorb (manufactured by Quantachrome Instruments Japan, LLC).

[0036] [Calculation of primary particle diameter from specific surface area] The average primary particle diameter was calculated from the specific surface area value obtained by the BET method using the following formula. In the examples described later, the density was 2.2 g / cm ３ The value used was: Primary particle diameter = 6000 / density / specific surface area

[0037] [Measurement of average secondary particle diameter by DLS (dynamic light scattering)] A particle diameter measuring device, Zetasizer Nano (manufactured by Malvern Panalytical), was used, and the Z average of the particles in each dispersion determined by dynamic light scattering was used as the average secondary particle diameter (DLS diameter).

[0038] [pH Measurement] This shows the value obtained from the pH measurement results of each dispersion, and was measured using a pH meter (multi-water quality meter MM-60R, pH electrode GST-5741C, manufactured by DKK-TOA Corporation).

[0039] [Measurement of Zeta Potential] Each dispersion was diluted with pure water to a silica concentration of 0.07% by mass, and the zeta potential was measured by electrophoretic light scattering using a zeta potential measurement system ELSZ-2000 (manufactured by Otsuka Electronics Co., Ltd.).

[0040] 2. Preparation of Dispersion and Measurement Results Preparation Example 1 A basic aluminum acetate aqueous solution used in the present invention was prepared by the following method. First, a commercially available basic aluminum chloride aqueous solution (Al ２ O ３ The resulting solution (concentration: 23.5% by mass, chloride ion concentration: 8.15% by mass, basicity: 83.3%, pH: 4.0) was diluted with pure water to give a solution of Al ２ O ３ An aqueous solution of basic aluminum chloride with a concentration of 5.2% by mass was prepared. This aqueous solution of basic aluminum chloride was then passed through a column packed with an acetate-type anion exchange resin at a space velocity of 5.0. Then, pure water was added to the column to remove the Al ２ O ３ An aqueous solution of basic aluminum acetate with a converted concentration of 5.0% by mass was obtained.

[0041] Preparation Example 2 The silica sol (acidic) used in the present invention was prepared by the following method. First, commercially available alkaline silica sol ST-YL (manufactured by Nissan Chemical Industries, Ltd., silica concentration 40% by mass, primary particle diameter 60 nm, secondary particle diameter 98 nm, pH 9.5) was passed through a column packed with a hydrogen ion type cation exchange resin at a space velocity of 5, and then pure water was added to obtain acidic silica sol OYL-30 (silica concentration 36% by mass, primary particle diameter 60 nm, pH 2.4). In the examples described later, the specific surface area of ​​OYL-30 was adjusted to 45.5 m.２ / g, and the "number of aluminum atoms in the free aluminum component / surface area of ​​silica particles" (unit: μmol / m ２ ), and "number of aluminum atoms in all aluminum components / surface area of ​​silica particles" (unit: μmol / m ２ ) was calculated based on the formula given above.

[0042] [Preparation Example 3] As another silica sol (acidic) used in the present invention, commercially available alkaline silica sol ST-OZL-35 (manufactured by Nissan Chemical Industries, Ltd., silica concentration 35 mass%, primary particle diameter 83 nm, secondary particle diameter 119 nm, pH 1.9) was used. In the examples described later, the specific surface area of ​​ST-OZL-35 was set to 32.9 m. ２ / g, and the "number of aluminum atoms in the free aluminum component / surface area of ​​silica particles" (unit: μmol / m ２ ), and "number of aluminum atoms in all aluminum components / surface area of ​​silica particles" (unit: μmol / m ２ ) was calculated based on the formula given above.

[0043] Example 1 The basic aluminum acetate aqueous solution obtained in Preparation Example 1, pure water, and acetic acid were placed in a 5 L container in amounts of 157 g, 726 g, and 14 g, respectively, and stirred for 10 minutes with a 5 cm diameter disper blade at a rotation speed of 500 rpm. Thereafter, the rotation speed of the disper blade was changed to 3000 rpm, and while stirring, 1103 g of the acidic silica sol OYL-30 obtained in Preparation Example 2 was added at a rate of 5 g per minute, thereby preparing a dispersion of Example 1. Measurements of the dispersion of Example 1 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 134 nm, the pH was 4.2, and the zeta potential was 41 mV.

[0044] A dispersion of Example 2 was prepared in the same manner as in Example 1, except that a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container in amounts of 307 g, 587 g, and 28 g, respectively, and the weight of the acidic silica sol OYL-30 added was 1078 g. Measurements of the dispersion of Example 2 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 118 nm, the pH was 4.0, and the zeta potential was 52 mV.

[0045] A dispersion of Example 3 was prepared in the same manner as in Example 1, except that a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container in amounts of 381 g, 513 g, and 35 g, respectively, and the weight of the acidic silica sol OYL-30 to be added was 1071 g. Measurements of the dispersion of Example 3 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 112 nm, the pH was 4.1, and the zeta potential was 55 mV.

[0046] Example 4 A dispersion of Example 4 was prepared in the same manner as in Example 1, except that a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container in amounts of 454 g, 440 g, and 41 g, respectively, and the weight of the acidic silica sol OYL-30 to be added was 1065 g. Measurements of the dispersion of Example 4 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 108 nm, the pH was 4.1, and the zeta potential was 54 mV.

[0047] A dispersion of Example 5 was prepared in the same manner as in Example 1, except that 730 g of a basic aluminum acetate aqueous solution, 178 g of pure water, and 66 g of acetic acid were placed in a 5 L container, and the weight of the acidic silica sol OYL-30 added was 1027 g. Measurements of the dispersion of Example 5 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 107 nm, the pH was 4.2, and the zeta potential was 50 mV.

[0048] A dispersion of Example 6 was prepared in the same manner as in Example 1, except that a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container in amounts of 938 g, 21 g, and 85 g, respectively, and the weight of the acidic silica sol OYL-30 added was 960 g. Measurements of the dispersion of Example 6 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 108 nm, the pH was 4.3, and the zeta potential was 50 mV.

[0049] Example 7 1752 g of the acidic silica sol OYL-30 prepared in Preparation Example 2 was placed in a 5 L container, and while stirring with a disperser blade having a diameter of 5 cm at a rotation speed of 3000 rpm, a commercially available aqueous solution of basic aluminum chloride (Al ２ O ３ 48 g of a 10% by weight sodium hydroxide solution (concentration: 23.5% by weight, chloride ion: 8.15% by weight, basicity: 83.3%, pH: 4.0) was added at a rate of 10 g per minute, followed by the addition of 181 g of pure water and stirring for 1 hour. 18 g of a 10% by weight sodium hydroxide aqueous solution was then added, followed by stirring for 2 hours to prepare a dispersion of Example 7. Measurements of the dispersion of Example 7 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 102 nm, the pH was 4.0, and the zeta potential was 46 mV.

[0050] Example 8 The basic aluminum acetate aqueous solution obtained in Preparation Example 1, pure water, and acetic acid were placed in a 5 L container at weights of 284 g, 598 g, and 32 g, respectively, and stirred for 10 minutes with a 5 cm diameter disper blade at 500 rpm. The rotation speed of the disper blade was then changed to 3000 rpm, and 1085 g of the acidic silica sol ST-OZL-35 described in Preparation Example 3 was added at a rate of 5 g per minute while stirring, thereby preparing a dispersion of Example 8. Measurements of the dispersion of Example 8 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 128 nm, the pH was 4.2, and the zeta potential was 54 mV.

[0051] A dispersion liquid of Comparative Example 1 was prepared in the same manner as in Example 1, except that 16 g, 858 g, and 1 g of a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container, and the weight of the acidic silica sol OYL-30 to be added was 1,124 g. Measurements of the dispersion liquid of Comparative Example 1 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 909 nm, the pH was 3.9, and the zeta potential was −4 mV.

[0052] A dispersion liquid of Comparative Example 2 was prepared in the same manner as in Example 1, except that 40 g, 835 g, and 4 g of a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container, and the weight of the acidic silica sol OYL-30 to be added was 1121 g. Measurements of the dispersion liquid of Comparative Example 2 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 1341 nm, the pH was 4.0, and the zeta potential was 15 mV.

[0053] A dispersion liquid of Comparative Example 3 was prepared in the same manner as in Example 1, except that 80 g, 798 g, and 7 g of a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container, and the weight of the acidic silica sol OYL-30 added was 1,115 g. Measurements of the dispersion liquid of Comparative Example 3 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 167 nm, the pH was 4.0, and the zeta potential was 37 mV.

[0054] A dispersion liquid of Comparative Example 4 was prepared in the same manner as in Example 1, except that a basic aluminum acetate aqueous solution, pure water, and acetic acid were placed in a 5 L container in amounts of 1066 g, 24 g, and 97 g, respectively, and the weight of the acidic silica sol OYL-30 to be added was 813 g. Measurements of the dispersion liquid of Comparative Example 4 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 106 nm, the pH was 4.3, and the zeta potential was 57 mV.

[0055] [Comparative Example 5] First, commercially available aluminum chloride hexahydrate (AlCl ３ ・6H ２ O) The powder was dissolved in AlCl ３The aluminum chloride solution was dissolved in pure water to a concentration of 11% by mass to obtain an aqueous aluminum chloride solution. Next, 350 g of the aqueous aluminum chloride solution and 170 g of pure water were placed in a 5 L container, and 390 g of a 10% by mass aqueous potassium hydroxide solution was added while stirring with a 5 cm diameter Disper blade at a rotation speed of 800 rpm. The obtained aluminum component-containing solution was slightly cloudy, and the pH measured by the measurement method described below was 4.4. Thereafter, the rotation speed of the Disper blade was changed to 3000 rpm, and while stirring, 1090 g of the acidic silica sol OYL-30 prepared was added at a rate of 5 g per minute to prepare a dispersion of Comparative Example 5. Measurements of the dispersion of Comparative Example 5 showed that the average secondary particle diameter (DLS diameter) immediately after preparation was 143 nm, the pH was 4.3, and the zeta potential was 54 mV.

[0056] 3. Method for Quantifying Free Aluminum Component and Total Aluminum Component in Dispersion Liquid> [Quantification of Free Aluminum Component] Each of the dispersion liquids obtained in Examples 1 to 7 and Comparative Examples 1 to 5 was diluted with pure water to a solids concentration (silica concentration + aluminum compound concentration in terms of aluminum oxide) of 10% by mass, and 10 g of this was taken and placed in a centrifuge tube equipped with an ultrafiltration membrane (Amicon Ultra-15 10K, manufactured by Merck), and centrifuged at 5,000 G for 30 minutes in a centrifuge (Suprema 21, manufactured by Tomy Seiko Co., Ltd.) to obtain a filtrate from which silica particles had been removed. The amount of aluminum contained in the obtained filtrate was measured by ICP emission spectrometry, and the amount of free aluminum component (concentration of free aluminum component in terms of aluminum) was determined. The results are shown in Table 1. The number of aluminum atoms in the free aluminum component was calculated, and this was divided by the surface area of ​​the silica particles to obtain a value (unit: μmol / m ２ ) are also shown in Table 1.

[0057] [Quantitative Determination of Total Aluminum Components] The amount of aluminum contained in each of the dispersions that had not been centrifugal filtered was measured by ICP atomic emission spectrometry, which was then heated and dissolved to obtain a sample, and the amount of total aluminum components (aluminum-equivalent concentration of all aluminum components) was calculated. The results are shown in Table 1. The number of aluminum atoms in all aluminum components was calculated, and this was divided by the surface area of ​​the silica particles (unit: μmol / m２ ) are also shown in Table 1.

[0058] 4. Evaluation of Storage Stability Change in Average Secondary Particle Diameter The dispersions obtained in Examples 1 to 6 and Comparative Examples 1 to 5, and a sample of the dispersion of Example 7, in which the solids concentration (silica concentration + aluminum compound concentration in terms of aluminum oxide) was adjusted to 20% by mass, were placed in a lidded bottle and stored in an electric furnace at 50°C. Two weeks after storage at 50°C, the samples were removed, and the average secondary particle diameter (DLS diameter) of the particles in each dispersion at that time was measured. The rate of change relative to the average secondary particle diameter immediately after preparation of the dispersion (sometimes referred to as the "DLS diameter change rate") was calculated. The results are shown in Table 2.

[0059] 5. Evaluation of Polishing Characteristics [Synthesis of Polyimide and Preparation of Negative-Type Photosensitive Resin Composition for Insulating Film Formation] 6.80 g (25.72 mmol) of BEM-S, 4.22 g (10.29 mmol) of BAPP, 5.81 g (15.43 mmol) of DAB-C18, and 95.37 g of N-ethyl-2-pyrrolidone were added to a four-neck flask and dissolved by stirring at room temperature under air. 21.32 g (34.46 mmol) of TMPBP-TME, 6.85 g (15.43 mmol) of 6FDA, and 159.63 g of N-ethyl-2-pyrrolidone were then added to the flask and stirred at 50°C for 22 hours to obtain a polyamic acid solution. Next, 150.00 g of N-ethyl-2-pyrrolidone, 15.75 g of acetic anhydride, and 2.60 g of triethylamine were added to the flask and stirred at 60°C for 3 hours to carry out chemical imidization. The reaction solution was diluted with 192.86 g of N-ethyl-2-pyrrolidone, and this diluted solution was added dropwise to methanol. The resulting precipitate was filtered, washed with methanol, and dried under reduced pressure at 60°C to obtain polyimide powder. The weight-average molecular weight (Mw) measured by GPC was 33,309, and the chemical imidization rate measured by NMR (THF-d8) was 99%.

[0060] 9.23 g of the obtained polyimide powder, 1.38 g of NK ester (A-DOD-N) as a crosslinking agent, and 1.38 g of BMI-689, 0.09 g of Adeka Arcles (NCI-930) as a photoradical initiator, and 0.55 g of IRGACURE [registered trademark] 819, 0.14 g of CBT-SG, 0.18 g of KBM-5103, 13.79 g of N-ethyl-2-pyrrolidone, 18.39 g of γ-butyrolactone, and 13.79 g of cyclohexanone were mixed and dissolved, and then filtered using a polypropylene filter with a pore size of 5 μm to prepare a negative photosensitive resin composition for forming an insulating film.

[0061] The compounds shown in the above synthesis examples are as follows. BEM-S: 2-(methacryloyloxy)ethyl 3,5-diaminobenzoate BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane DAB-C18: 4-octadecyloxy-1,3-phenylenediamine TMPBP-TME: 2,2',3,3',5,5'-hexamethyl-[1,1'-biphenyl]-4,4'-diylbis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate) (manufactured by Honshu Chemical Industry Co., Ltd.) 6FDA: 4,4'-[perfluoro(propane-2,2-diyl)]diphthalic anhydride (manufactured by Daikin Industries, Ltd.) NK ester A-DOD-N: 1,10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) BMI-689: Maleimide compound (manufactured by Designer Molecules Inc.) CBT-SG: Mixture of 4-carboxybenzotriazole and 5-carboxybenzotriazole (manufactured by Johoku Chemical Industry Co., Ltd.) KBM-5103: 3-acryloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0062] The weight average molecular weights (Mw) shown in the above synthesis examples are the results of measurement by gel permeation chromatography (abbreviated as GPC in this specification). For the measurement, a GPC device (HLC-8320GPC (manufactured by Tosoh Corporation)) was used, and the measurement conditions were as follows: Column: Shodex (registered trademark) KD-805 / Shodex (registered trademark) KD-803 (manufactured by Showa Denko K.K.) Column temperature: 50°C Flow rate: 1 mL / min Eluent: N,N-dimethylformamide (DMF), lithium bromide monohydrate (30 mM) / phosphoric acid (30 mM) / tetrahydrofuran (1% by volume) Standard sample: polyethylene oxide

[0063] The chemical imidization ratios shown in the above synthesis examples are the results of measurements using a nuclear magnetic resonance spectrometer (hereinafter abbreviated as NMR in this specification). For the measurements, an NMR spectrometer (JNM-ECA500) (manufactured by JEOL Ltd.) was used, and the measurement conditions were as follows: Measurement temperature: room temperature Measurement solvent: deuterated tetrahydrofuran (THF-d8) Note that the chemical imidization ratio was calculated using the integrated peak value of a proton derived from a structure that does not change before and after imidization as the reference proton, and the integrated peak value of this proton and the integrated peak value of a proton derived from the NH group of the amic acid that appears in the vicinity of 9.5 ppm to 11.0 ppm, according to the following formula: Chemical imidization rate (%)=(1−α×x / y)×100 In the above formula, x is the integrated value of the proton peak derived from the NH group of the amic acid, y is the integrated value of the peak of the reference proton, and α is the ratio of the number of reference protons to one NH group proton of the amic acid in the case of polyamic acid (imidization rate 0%).

[0064] [Preparation of Polyimide Film as Film to be Polished] The negative photosensitive resin composition for forming an insulating film obtained above was spin-coated onto a 4-inch silicon wafer and baked on a hot plate at 115°C for 270 seconds. An i-line aligner (PLA-501, manufactured by Canon Inc.) was used to apply 500 mJ / cm to the obtained photosensitive resin film on the wafer. ２ After the entire surface was exposed to light with a high-temperature clean oven (CLH-21CD(V)-S, Koyo Thermo Systems Co., Ltd.), the film was baked in a nitrogen atmosphere at 230°C for 2 hours to form a polyimide film of about 6 µm.

[0065] [Evaluation of Polishing Rate] Each of the dispersions obtained above was diluted with pure water to a solids concentration (silica concentration + aluminum compound concentration in terms of aluminum oxide) of 10 mass %, and the polyimide film obtained above was polished using the polishing dispersion by the following method. Polishing machine: Lapmaster LP-18 Pressure: 250 g / cm ２ Platen rotation speed: 80 rpm Substrate rotation speed: 80 rpm Polishing pad: Nitta DuPont IC1000 (grating groove: width 2 mm, pitch: 20 mm) Polishing composition supply rate: 100 mL / min Polishing time: 1 minute Polishing object: 1 wafer with polyimide film Note that Comparative Examples 3 and 5, in which the rate of change in secondary particle diameter exceeded 100%, were excluded from the evaluation of the polishing rate.

[0066] The polishing rate was calculated from the amount of film thickness reduction before and after polishing the polyimide film. The film thickness was measured using an optical film thickness meter at five locations: the center of the wafer and four locations 1 cm from the periphery (the 0 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock positions when the orientation flat of the silicon wafer is set at the 0 o'clock position on a clock). The film thickness measurement conditions were as follows: Apparatus: FILMETRICS F20-EXR Film refractive index: 1.59 Analysis method: Grid Search

[0067] The compositions and zeta potentials of the 10% by mass diluted dispersions of Examples 1 to 7 and Comparative Examples 1 to 5 are shown in Table 1, and the evaluation results of the storage stability at 20% by mass and the polishing rate using the 10% by mass diluted dispersions are shown in Table 2.

[0068]

[0069]

[0070] As shown in the evaluation results in Table 2, it was found that the dispersions and polishing compositions of the examples having the technical features of the present invention, unlike the dispersions and polishing compositions of the comparative examples, can polish a polyimide film, which is a resin, at a high polishing rate and also have excellent storage stability even at a high concentration of 20 mass%. Therefore, it was demonstrated that the use of the specific dispersion containing silica particles of the present invention and the polishing composition containing said dispersion can achieve both polishing properties and storage stability.

[0071] The dispersion or polishing composition of the present invention is capable of polishing resins and the like at a high polishing rate, and further has excellent storage stability even at high concentrations. Therefore, it is possible to provide a dispersion that can achieve both polishing properties and storage stability, and a polishing composition containing the dispersion.

Claims

1. A dispersion comprising silica particles and an aqueous solution of a basic aluminum salt, wherein at least a portion of the surface of the silica particles is coated with an aluminum-containing compound, and the number of aluminum atoms in the free aluminum component in the dispersion is 1 to 60 μmol / m relative to the surface area of ​​the silica particles. ２ That is, a dispersion.

2. The dispersion according to claim 1, wherein the silica particles in the dispersion are present in an amount of 8 to 40% by mass, calculated as silica solids, based on the total mass of the dispersion.

3. The number of aluminum atoms in the total aluminum component in the dispersion is 6 to 65 μmol / m relative to the surface area of ​​the silica particles. ２ 2. The dispersion of claim 1, wherein 4. The dispersion of claim 1, wherein the basic aluminum salt comprises basic aluminum acetate.

5. The basic aluminum acetate is Al(OH) Ｘ (CH ３ COO) ３－Ｘ 5. The dispersion according to claim 4, having a chemical composition represented by the formula: (wherein X is a real number of 0.9 to 2.7).

6. The dispersion according to claim 1, wherein the particles contained in the dispersion have a zeta potential of 30 to 65 mV.

7. The dispersion according to claim 1, wherein the silica particles have an average primary particle size of 10 to 500 nm as measured by nitrogen gas adsorption.

8. A polishing composition comprising the dispersion according to any one of claims 1 to 7.

9. The polishing composition according to claim 8, which is used for polishing resins.

10. The polishing composition according to claim 9, wherein the resin is a polyimide.

Images