Amino-modified colloidal silica and method for producing amino-modified colloidal silica

Abstract

Provided is an amino group-modified colloidal silica that can form a polished surface with significantly reduced surface roughness at a high polishing rate. The amino group-modified colloidal silica contains amino group-modified silica particles in which the content of coarse particles having a particle size of 0.2 μm or more is 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass, and preferably the amino group-modified colloidal silica has an average secondary particle size of 10 to 150 nm.

Description

[Technical Field]

[0001] The present invention relates to amino group-modified colloidal silica and a method for producing amino group-modified colloidal silica. [Background technology]

[0002] In the semiconductor manufacturing process, semiconductor wafers are held by a component called a carrier, and the wafer is brought into contact with and rotated on a polishing pad while a slurry containing chemicals and abrasive grains is poured over it, polishing the semiconductor wafer until it is flat and smooth.

[0003] In the above-mentioned polishing methods, chemical mechanical polishing (CMP) is also used, which utilizes the chemical polishing action of chemicals and the mechanical polishing action of abrasive grains.

[0004] In chemical mechanical polishing (CMP), there is a demand for polishing abrasive grains that can produce a polished surface with reduced surface roughness on the semiconductor wafer to be polished.

[0005] Under these circumstances, colloidal silica particles, i.e., aminosilane-modified colloidal silica, which is colloidal silica (silica sol) modified with an aminosilane coupling agent (a silane coupling agent having an amino group), have been proposed as abrasive grains for polishing semiconductor wafers (see Patent Document 1 (JP 2022-179329 A)). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2022-179329 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0007] According to Patent Document 1, a cation-modified silica dispersion with a small number of coarse particles with a particle diameter of 0.7 μm or more can be produced by mixing a solution containing 0.03 mass % or more but less than 1 mass % of a silane coupling agent having a cationic group such as an amino group with a dispersion containing silica particles.

[0008] However, the inventors of the present invention have found that the silica dispersion modified with an aminosilane coupling agent (amino group-modified colloidal silica) obtained by the method described in Patent Document 1 contains many coarse particles with a particle diameter of 0.2 μm or more, and when used as a polishing composition for semiconductor wafers, the polished surface roughness increases.

[0009] Under these circumstances, an object of the present invention is to provide an amino group-modified colloidal silica capable of forming a polished surface with significantly reduced surface roughness at a high polishing rate, and a method for producing the same. [Means for solving the problem]

[0010] The present inventors have conducted extensive research to solve the above technical problems, and have found that the above problems can be solved by amino group-modified colloidal silica containing amino group-modified silica particles in which the content of coarse particles having a particle size of 0.2 μm or more is 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass, and that the amino group-modified colloidal silica can be produced by a specific production method. Based on these findings, the present invention has been completed.

[0011] That is, the present invention is (1) An amino-modified colloidal silica characterized by containing amino-modified silica particles in which the content of coarse particles having a particle size of 0.2 μm or more is 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass; (2) The amino group-modified colloidal silica according to (1) above, wherein the average secondary particle diameter of the amino group-modified silica particles is 10 to 150 nm. (3) A method for producing the amino group-modified colloidal silica described in (1) above, comprising the steps of: colloidal silica obtained by dispersing silica particles in an aqueous medium containing 3% by mass to 95% by mass of alcohol, the content of coarse particles having a particle size of 0.2 μm or more being 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass; an aminosilane coupling agent dispersion containing 70.0% by mass to 99.5% by mass of alcohol; Contact temperature range: 5℃~60℃ A method for producing amino group-modified colloidal silica, This provides: [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an amino group-modified colloidal silica and a method for producing the amino group-modified colloidal silica, which are capable of forming a polished surface with significantly reduced surface roughness at a high polishing rate. DETAILED DESCRIPTION OF THE INVENTION

[0013] First, the amino group-modified colloidal silica according to the present invention will be described. The amino group-modified colloidal silica according to the present invention is characterized by containing amino group-modified silica particles in which the content of coarse particles having a particle size of 0.2 μm or more is 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass.

[0014] The amino group-modified colloidal silica according to the present invention contains amino group-modified silica particles in which amino groups are fixed to silica particles constituting colloidal silica. The amino group-modified colloidal silica according to the present invention is suitably one containing amino group-modified silica particles in which an aminosilane compound (a silane compound having an amino group) is fixed to silica particles constituting colloidal silica by chemical bonding.

[0015] Examples of the aminosilane compound include various aminosilane coupling agents.

[0016] Examples of the aminosilane coupling agent include one or more selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 4-amino-3,3-dimethylbutyltriethoxysilane, N-methylaminopropyltrimethoxysilane, (N,N-dimethyl-3-aminopropyl)trimethoxysilane, 2-(4-pyridylethyl)triethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, and the like, and one or more selected from 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane are suitable.

[0017] In the amino group-modified colloidal silica according to the present invention, by using the aminosilane coupling agent as the aminosilane compound, Si-O-Si bonds are formed with the colloidal silica through a hydrolysis reaction and a dehydration condensation reaction, and the surfaces of the silica particles constituting the colloidal silica can be modified with amino groups (amino groups can be fixed).

[0018] As described above, the amino group-modified colloidal silica according to the present invention is obtained by dispersing amino group-modified silica particles, which have amino groups (—NH) fixed to silica particles constituting colloidal silica, in a solvent. Therefore, the amino group-modified silica particles have a basic structure derived from the silica particles constituting colloidal silica.

[0019] In the present application, it has been confirmed by X-ray photoelectron spectroscopy (XPS) shown below that the amino group-modified colloidal silica contains amino group-modified silica particles modified with amino groups. First, the measurement sample is centrifuged at 77,000 G at 5°C for 90 minutes. The resulting precipitate is dried at 60°C for 12 hours, and then the resulting solid is crushed in a mortar with a pestle and dried at 60°C under reduced pressure of -0.1 MPa or less for 2 hours to prepare a dry powder. Using this dry powder, the presence or absence of amino groups on the silica particle surface is confirmed by X-ray photoelectron spectroscopy under the following conditions. Measuring equipment: AXIS-NOVA manufactured by Shimadzu Corporation Irradiation X-ray: Al-Kα (15kV, 10mA) Analytical X-ray spot diameter: 300 x 700 μm

[0020] As will be described later, one method for preparing colloidal silica is to stir, for example, tetramethoxysilane (Si(OCH3)4) in an organic solvent containing water, thereby forming a dimer through hydrolysis and dehydration condensation, and this dimer then polymerizes (oligomerizes) to form spherical primary silica particles in the solvent. These spherical primary silica particles dispersed in the solvent correspond to colloidal silica. The colloidal silica contains not only primary silica particles but also secondary silica particles formed by association of the primary silica particles, and these secondary silica particles are dispersed in the solvent together with the primary silica particles. The amino group-modified colloidal silica according to the present invention corresponds to the above colloidal silica containing amino group-modified silica particles in which amino groups are fixed to silica particles dispersed in the colloidal silica.

[0021] The average primary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention (average diameter of the amino group-modified silica primary particles) is not particularly limited, but is preferably 5 nm or more and 120 nm or less.

[0022] The average primary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is preferably 120 nm or less, more preferably 110 nm or less, and even more preferably 100 nm or less.

[0023] When the average primary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is the above-mentioned value (upper limit value) or less, a polished surface with superior flatness can be formed when polishing is performed using the amino group-modified colloidal silica according to the present invention.

[0024] The average primary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is preferably 5 nm or more, more preferably 6 nm or more, and even more preferably 7 nm or more.

[0025] When the average primary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is equal to or greater than the above value (lower limit), particle aggregation is less likely to occur when polishing is performed using the amino group-modified colloidal silica according to the present invention, and therefore a polished surface with superior flatness can be formed.

[0026] In the present application, the average primary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica refers to a value measured by the BET method described below. That is, first, the amino group-modified colloidal silica is pre-dried on a hot plate at 150°C, and then heat-treated at 800°C for 1 hour to prepare a measurement sample. The specific surface area S of the obtained measurement sample is measured by the BET method (BET specific surface area). For nearly spherical particles, the average primary particle diameter (nm) of amino group-modified silica particles is calculated using the following formula: Average primary particle diameter of amino group-modified silica particles (nm) = 6000 / (BET specific surface area S (m 2 / g) x true density (g / cm 3 )) where the true density of the silica particles is 2.2 g / cm 3 Based on this, the average primary particle size (nm) of the amino group-modified silica particles is calculated by the following formula: Average primary particle diameter of amino group-modified silica particles (nm) = 2727 / BET specific surface area S (m 2 / g) It can be calculated by:

[0027] As described above, the amino group-modified colloidal silica contains amino group-modified silica particles in which amino groups are fixed to silica particles constituting the colloidal silica. Therefore, in the present application, the average primary particle diameter of the amino group-modified silica particles contained in the amino group-modified colloidal silica (average diameter of the amino group-modified silica primary particles) is defined as the value calculated by the above method based on the true density of the silica particles, as described above.

[0028] The amino group-modified colloidal silica according to the present invention contains amino group-modified silica secondary particles formed by association of amino group-modified silica primary particles. The amino group-modified silica secondary particles contained in the amino group-modified colloidal silica according to the present invention, together with the amino group-modified silica primary particles contained in the amino group-modified colloidal silica according to the present invention, constitute the main particles of the amino group-modified silica particles, and are distinguished from the amino group-modified silica secondary particles and coarse particles (described below) formed by aggregation of the aminosilane coupling agent.

[0029] The average secondary particle diameter of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention (average diameter of the amino group-modified silica secondary particles) is preferably 10 to 150 nm.

[0030] The average secondary particle diameter of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is preferably 150 nm or less, more preferably 145 nm or less, even more preferably 140 nm or less, still more preferably 135 nm or less, and even more preferably 130 nm or less.

[0031] When the average secondary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is the above-mentioned value (upper limit value) or less, a polished surface with superior flatness can be formed when polishing is performed using the amino group-modified colloidal silica according to the present invention.

[0032] The average secondary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is preferably 10 nm or more, more preferably 12 nm or more, even more preferably 15 nm or more, and particularly preferably 20 nm or more.

[0033] When the average secondary particle diameter of the amino group-modified silica particles contained in the amino group-modified colloidal silica according to the present invention is equal to or greater than the above value (lower limit), aggregation of the amino group-modified silica particles is less likely to occur when polishing is performed using the amino group-modified colloidal silica according to the present invention, and therefore a polished surface with superior flatness can be formed.

[0034] In the present application, the average secondary particle size of the amino group-modified silica particles contained in the amino group-modified colloidal silica refers to a value measured by the dynamic light scattering method described below. That is, first, a 0.3 mass % citric acid aqueous solution is added to the amino group-modified colloidal silica to be used as a measurement sample, and the mixture is uniformly diluted to a silica particle concentration of 0.8 mass %, and the resulting diluted solution is used as the measurement sample. The average particle size measured by dynamic light scattering using the above measurement sample and the zeta potential, particle size, and molecular weight measurement system "ELSZ-2000S" manufactured by Otsuka Electronics Co., Ltd. is taken as the average secondary particle size of the amino group-modified silica particles.

[0035] In the amino group-modified colloidal silica according to the present invention, the content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles is 10,000,000 particles / mL or less, preferably 9,800,000 particles / mL or less, and more preferably 9,600,000 particles / mL or less, when the silica particle concentration (in the amino group-modified colloidal silica) is 1% by mass.

[0036] In the amino group-modified colloidal silica according to the present invention, the content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles is equal to or less than the above value (upper limit) when the silica particle concentration in the amino group-modified colloidal silica is 1 mass %, so that when chemical mechanical polishing (CMP) is performed using the amino group-modified colloidal silica according to the present invention, roughness of the polished surface due to the presence of coarse particles can be suppressed, and a polished surface with high flatness can be easily formed.

[0037] In the amino group-modified colloidal silica according to the present invention, the lower limit of the content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles is not particularly limited, but in the amino group-modified colloidal silica according to the present invention, the content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles can be 1,000 particles / mL or more, and preferably 0 particles / mL or more, when the silica particle concentration is 1% by mass.

[0038] According to the investigations of the present inventors, it has been found that in the production process of conventionally known amino group-modified colloidal silica, the amino group-containing silane coupling agents used for the amino group modification undergo hydrolysis and condensation polymerization with each other, and that this tends to result in the inclusion of a large amount of coarse particles with a particle size of 0.2 μm or more, and that when the resulting amino group-modified colloidal silica is used as abrasive grains for polishing, the roughness of the polished surface increases. The amino group-modified colloidal silica according to the present invention has a reduced content of coarse particles having a particle size of 0.2 μm or more. Therefore, when chemical mechanical polishing (CMP) is performed using the amino group-modified colloidal silica according to the present invention, a highly flat polished surface can be easily formed at a high polishing rate.

[0039] In the present application, the content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles constituting the amino group-modified colloidal silica refers to the value measured by the particle size distribution measurement method using a number counting method described below. <Method for measuring the content of coarse particles with a particle size of 0.2 μm or more contained in amino group-modified silica particles> Ultrapure water is added to the amino group-modified colloidal silica to be measured to dilute it so that the silica particle concentration becomes 1% by mass. The obtained diluted solution is used as a measurement sample, and the number of coarse particles with a particle size of 0.2 μm or more is measured using an Accusizer FX-nano manufactured by Particle Sizing Systems Inc. under the following measurement conditions. <System Setup> ·Stirred Vessel Volume: 13.22 mL ·Sample Loop Volume: 0.52 mL ·Autodilution delay time : 3 sec. ·Normal Speed ​​Flow Rate: 15 mL / min <Sensor Setup Menu> ·FX-Nano HG Minimum Size: 0.15μm ·FX-Nano HG Maximum Size: 0.27μm ·FX-Nano HG Collection Time: 60sec. ·HG Starting Concentration : 8000♯ / mL

[0040] The pH of the amino group-modified colloidal silica according to the present invention may be appropriately set depending on the application, and is not particularly limited, but is preferably 2.0 or more and 11.0 or less.

[0041] The pH of the amino group-modified colloidal silica according to the present invention is preferably 2.0 or higher, more preferably 2.2 or higher, and even more preferably 2.4 or higher. When the pH of the amino group-modified colloidal silica according to the present invention is at least the above value (lower limit), the dispersion stability of the silica particles in the amino group-modified colloidal silica according to the present invention is likely to be improved, and particle aggregation of the amino group-modified colloidal silica according to the present invention is less likely to occur during storage or polishing, making it possible to easily form a polished surface with high flatness when used as abrasive grains for polishing.

[0042] The pH of the amino group-modified colloidal silica according to the present invention is preferably 11.0 or less, more preferably 10.8 or less, even more preferably 10.6 or less, and particularly preferably 10.4 or less. When the pH of the amino group-modified colloidal silica according to the present invention is the above-mentioned value (upper limit value) or less, the long-term dispersion stability of the amino group-modified colloidal silica can be further improved, and when used as abrasive grains for polishing, a highly flat polished surface can be easily formed.

[0043] In the present application, pH refers to a value measured using a pH meter F-2000PI (manufactured by Horiba, Ltd.) equipped with a pH electrode 9615S-10D (manufactured by Horiba, Ltd.).

[0044] The content of the amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is not particularly limited, but is preferably 1% by mass or more and 50% by mass or less, when the content of the amino group-modified colloidal silica is taken as 100% by mass.

[0045] The content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on 100% by mass of the total content of amino group-modified colloidal silica.

[0046] When the content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is equal to or greater than the above value (lower limit), the polishing performance is further improved when the amino group-modified colloidal silica dispersion according to the present invention is used as abrasive grains for polishing.

[0047] The content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. When the content of the amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is the above value (upper limit) or less, the dispersion stability of the amino group-modified silica particles can be further improved.

[0048] In the present application, the content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention means a value measured by the following measurement method. That is, 10.0 g of amino group-modified colloidal silica was dried on a hot plate at 150°C, and then heat-treated at 800°C for 1 hour to remove moisture. The amount of the resulting solid content was designated as Wg, and the value was calculated using the following formula: Content of amino group-modified silica particles in amino group-modified colloidal silica (mass%) = (W / 10.0) x 100 The content of the silica particles corresponds to the total content of amino group-modified silica primary particles, amino group-modified silica secondary particles, and coarse particles in the amino group-modified colloidal silica.

[0049] The amino group-modified colloidal silica according to the present invention may contain metal impurities.

[0050] In the amino group-modified colloidal silica according to the present invention, the metal impurities can be one or more selected from sodium, potassium, iron, aluminum, calcium, magnesium, titanium, nickel, chromium, copper, zinc, lead, silver, manganese, cobalt, and the like.

[0051] In the amino group-modified colloidal silica according to the present invention, the total content of metal impurities is preferably 1 ppm by mass or less. By keeping the total content of metal impurities at 1 ppm by mass or less, the amino group-modified colloidal silica according to the present invention can be suitably used as abrasive grains for polishing electronic materials such as semiconductor wafers.

[0052] In the present application, the content of metal impurities means a value measured using an atomic absorption spectrometer.

[0053] The amino group-modified colloidal silica according to the present invention can be suitably prepared by the production method according to the present application, which will be described later.

[0054] According to the present invention, it is possible to provide an amino group-modified colloidal silica that can form a polished surface with significantly reduced surface roughness at a high polishing rate.

[0055] Next, a method for producing the amino group-modified colloidal silica according to the present invention will be described. The method for producing amino group-modified colloidal silica according to the present invention comprises the steps of: The method for producing amino group-modified colloidal silica according to the present invention comprises the steps of: colloidal silica obtained by dispersing silica particles in an aqueous medium containing 3% by mass to 95% by mass of alcohol, the content of coarse particles having a particle size of 0.2 μm or more being 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass; an aminosilane coupling agent dispersion containing 70.0% by mass to 99.5% by mass of alcohol; Contact temperature range: 5℃~60℃ It is characterized by the following.

[0056] (Raw material colloidal silica) In the method for producing amino group-modified colloidal silica according to the present invention, silica particles having a content of coarse particles having a particle size of 0.2 μm or more of 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass are used as the raw material colloidal silica.

[0057] In the method for producing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material can be appropriately selected from colloidal silica having desired properties produced by a known production method, and examples thereof include colloidal silica having desired properties produced by a sol-gel method.

[0058] In the method for producing amino group-modified colloidal silica according to the present invention, colloidal silica used as a raw material is preferably produced by a sol-gel method, since it contains a small amount of metal impurities that can diffuse into semiconductors and corrosive ions such as chloride ions.

[0059] In the method for producing amino group-modified colloidal silica according to the present invention, when colloidal silica produced by a sol-gel method is used as the raw material colloidal silica, the method for producing the colloidal silica can be a conventionally known method. Specifically, the colloidal silica can be produced by carrying out a hydrolysis-condensation reaction using one or more hydrolyzable silicon compounds (e.g., alkoxysilanes or derivatives thereof) as raw materials.

[0060] The silicon compound is represented by the following general formula (1): Si(OR)4(1) (In the above general formula (1), the R group is an alkyl group having 1 to 8 carbon atoms.) Examples of the tetraalkoxysilane include tetraalkoxysilanes represented by the following formula:

[0061] In the silicon compound represented by general formula (1) or a derivative thereof, the R group is an alkyl group having 1 to 8 carbon atoms, preferably an alkyl group having 1 to 4 carbon atoms.

[0062] In the silicon compound represented by general formula (1) or a derivative thereof, examples of the R group include one or more groups selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group, and preferably one or more groups selected from a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group.

[0063] The silicon compound represented by the general formula (1) is preferably tetramethoxysilane in which the R group is a methyl group, tetraethoxysilane in which the R group is an ethyl group, or tetraisopropoxysilane in which the R group is an isopropyl group. Furthermore, examples of the derivatives of the silicon compound represented by general formula (1) include low condensates obtained by partially hydrolyzing the silicon compound represented by general formula (1) (tetraalkoxysilane). As the silicon compound represented by general formula (1) or its derivative, tetramethoxysilane is preferred because the hydrolysis rate can be easily controlled, fine silica particles can be easily obtained, and there is little residual unreacted material.

[0064] The silicon compound represented by the general formula (1) or its derivative undergoes hydrolysis and condensation in a reaction solvent to form colloidal silica.

[0065] Examples of the dispersion solvent (reaction solvent) used when the silicon compound represented by general formula (1) or its derivative is hydrolyzed and condensed include water and organic solvents containing water. The organic solvent may be at least one selected from hydrophilic organic solvents such as alcohols, such as methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, and 1,4-butanediol, and ketones, such as acetone and methyl ethyl ketone. Among these organic solvents, it is particularly preferable to use alcohols such as methanol, ethanol, and isopropanol. From the viewpoint of post-treatment of the reaction solvent, it is more preferable to use alcohols having the same alkyl group as the alkyl group (R group) of the starting silicon compound (e.g., methanol for tetramethoxysilane).

[0066] The amount of the organic solvent used is not particularly limited, but is preferably 5 to 50 moles per mole of the silicon compound represented by general formula (1) or its derivative. If the amount of the organic solvent used is less than 5 moles per mole of the silicon compound represented by general formula (1) or its derivative, it may be difficult to exhibit compatibility with the silicon compound represented by general formula (1), and if it exceeds 50 moles per mole of the silicon compound represented by general formula (1) or its derivative, the production efficiency may decrease.

[0067] The amount of water to be added to the silicon compound represented by general formula (1) or its derivative is not particularly limited as long as it is the amount required for hydrolysis of the silicon compound represented by general formula (1), and is preferably about 2 to 200 moles per mole of the silicon compound represented by general formula (1). When an organic solvent containing water is added to the silicon compound represented by general formula (1) or a derivative thereof, the amount of water mixed with the organic solvent significantly affects the particle size of the colloidal silica that is formed. By increasing the amount of water added relative to the amount of organic solvent added, the particle size of the resulting colloidal silica can be relatively increased, and by decreasing the amount of water added relative to the amount of organic solvent added, the particle size of the resulting colloidal silica can be relatively decreased. In this way, by changing the mixing ratio of water and organic solvent, the particle size of the resulting colloidal silica can be adjusted as desired.

[0068] The reaction solvent for the hydrolysis and condensation reaction of silicon compounds to obtain colloidal silica is preferably adjusted to alkaline in the presence of a basic catalyst. By the above adjustment, the pH of the reaction solvent is controlled to preferably 8.0 or more and 11.0 or less, more preferably 8.5 or more and 10.5 or less, and colloidal silica can be rapidly formed.

[0069] From the viewpoint of preventing the incorporation of impurities, the basic catalyst is preferably one or more selected from organic amines and ammonia, and more preferably one or more selected from ethylenediamine, diethylenetriamine, triethylenetetraamine, 3-ethoxypropylamine, ammonia, urea, ethanolamine, tetramethylammonium hydroxide, and the like.

[0070] To hydrolyze and condense a silicon compound in a reaction solvent, the silicon compound represented by general formula (1) or its derivative is added to a solvent containing water and stirred at a temperature generally between 0°C and 100°C, preferably between 0°C and 50°C.

[0071] By stirring a silicon compound in a solvent containing water, hydrolysis and dehydration condensation reactions of the silicon compound represented by general formula (1) or its derivatives proceed. First, the silicon compound represented by general formula (1) or its derivatives undergoes dehydration condensation to form a dimer. This dimer then polymerizes (oligomerizes) to form spherical primary silica particles in the solvent, thereby obtaining colloidal silica in which the primary silica particles are dispersed in the solvent. The colloidal silica also contains secondary particles (secondary silica particles) formed by association of primary silica particles. Colloidal silica with a uniform silica particle size can be obtained by hydrolyzing and condensing silicon compounds while stirring them in a solvent containing water.

[0072] The colloidal silica obtained by the above hydrolysis-condensation reaction (sol-gel method) can be used as the raw material colloidal silica in the production method according to the present invention by adjusting the concentration appropriately.

[0073] In the method for producing amino group-modified colloidal silica according to the present invention, the colloidal silica as a raw material is prepared by adding 3% by mass of alcohol to The colloidal dispersion of silica particles is preferably in an aqueous medium containing 4 to 90% by mass of alcohol, and more preferably in an aqueous medium containing 5 to 85% by mass of alcohol.

[0074] In the present application, the alcohol content in the aqueous medium constituting the raw material colloidal silica refers to a value measured by the following method. (Method for measuring alcohol content in aqueous medium) The colloidal silica to be measured is centrifuged at 215,000 G for 90 minutes, and the supernatant is collected. The collected supernatant is analyzed using a gas chromatograph (GC-2104, manufactured by Shimadzu Corporation) equipped with a flame ionization detector (FID) in accordance with JIS K0114 to determine the alcohol content.

[0075] In the method for producing amino group-modified colloidal silica according to the present invention, the alcohol contained in the aqueous medium that constitutes the raw material colloidal silica can be one or more alcohols selected from methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, 1,4-butanediol, etc., and it is particularly preferable to use alcohols such as methanol, ethanol, and isopropanol. These alcohols may be the dispersion solvents used in preparing the raw colloidal silica, or may be added separately after preparing the raw colloidal silica.

[0076] In the method for producing amino group-modified colloidal silica according to the present invention, the solvent contained together with the alcohol in the aqueous medium constituting the raw material colloidal silica can be water. The solvent used together with the alcohol to disperse the colloidal silica may be the dispersion solvent used when preparing the colloidal silica, or may be a solvent added separately after preparing the colloidal silica.

[0077] In the method for producing amino group-modified colloidal silica according to the present invention, by using an aqueous medium containing a predetermined amount of alcohol as the raw material colloidal silica, when the colloidal silica is brought into contact with an aminosilane coupling agent described below, the dispersibility of the aminosilane coupling agent is easily improved, and the generation of aggregated particles due to hydrolysis and condensation polymerization of the aminosilane coupling agents themselves can be easily suppressed.

[0078] In the method for producing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material preferably has an average secondary particle diameter of silica particles (average diameter of secondary silica particles) of 10 to 150 nm.

[0079] In the method for producing amino group-modified colloidal silica according to the present invention, the average secondary particle diameter of the silica particles constituting the colloidal silica is preferably 150 nm or less, more preferably 145 nm or less, still more preferably 140 nm or less, even more preferably 135 nm or less, and particularly preferably 130 nm or less.

[0080] In the method for producing amino group-modified colloidal silica according to the present invention, since the average secondary particle diameter of the silica particles constituting the colloidal silica is the above-mentioned value (upper limit value) or less, when polishing is performed using the amino group-modified colloidal silica obtained by the production method of the present invention, a polished surface with superior flatness can be formed.

[0081] In the method for producing amino group-modified colloidal silica according to the present invention, the average secondary particle size of the silica particles constituting the colloidal silica is preferably 10 nm or more, more preferably 12 nm or more, even more preferably 15 nm or more, and still more preferably 20 nm or more.

[0082] When the average secondary particle diameter of the silica particles constituting the colloidal silica is equal to or greater than the above value (lower limit), aggregation of the silica particles is less likely to occur when polishing is performed using the amino group-modified colloidal silica obtained by the production method according to the present invention, and therefore a polished surface with superior flatness can be formed.

[0083] In the present application, the average secondary particle size of the silica particles constituting the colloidal silica can be measured by the same method as the method for measuring the average secondary particle size of the silica particles contained in the amino group-modified colloidal silica described above.

[0084] In the method for producing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a starting material has a content of coarse particles having a particle size of 0.2 μm or more contained in silica particles of 10,000,000 particles / mL or less, preferably 9,800,000 particles / mL or less, and more preferably 9,600,000 particles / mL or less, when the silica particle concentration is 1% by mass.

[0085] In the amino group-modified colloidal silica according to the present invention, when the silica particles constituting the colloidal silica contain coarse particles having a particle size of 0.2 μm or more at a silica particle concentration of 1 mass %, the content of coarse particles not more than the above value (upper limit), when the amino group-modified colloidal silica obtained by the production method according to the present invention is used for chemical mechanical polishing (CMP), roughening of the polished surface due to the presence of coarse particles can be suppressed, and a polished surface with high flatness can be easily formed.

[0086] In the method for producing amino group-modified colloidal silica according to the present invention, the lower limit of the content of coarse particles having a particle size of 0.2 μm or more contained in the silica particles constituting the colloidal silica is not particularly limited, but the content of coarse particles having a particle size of 0.2 μm or more contained in the silica particles constituting the colloidal silica can be 1,000 particles / mL or more, and preferably 0 particles / mL or more, when the silica particle concentration is 1% by mass.

[0087] In the present application, the content of coarse particles having a particle size of 0.2 μm or more contained in the silica particles constituting the colloidal silica is as follows: The content of coarse particles having a particle size of 0.2 μm or more contained in the silica particles constituting the amino group-modified colloidal silica can be measured by the same method as that for measuring the content of coarse particles having a particle size of 0.2 μm or more contained in the silica particles constituting the amino group-modified colloidal silica described above.

[0088] In the method for producing amino group-modified colloidal silica according to the present invention, an aminosilane coupling agent dispersion containing 70.0% by mass to 99.5% by mass of alcohol is used together with the colloidal silica.

[0089] In the method for producing amino group-modified colloidal silica according to the present invention, the aminosilane coupling agent dispersion contains 70.0 mass % to 99.5 mass %, preferably 72.0 mass % to 99.0 mass %, and more preferably 74.0 mass % to 98.5 mass % of alcohol.

[0090] In the method for producing amino group-modified colloidal silica according to the present invention, the alcohol content in the aminosilane coupling agent dispersion is within the above range, so that the aminosilane coupling agent can be sufficiently dispersed while being prevented from being unevenly distributed in the dispersion. Therefore, when the aminosilane coupling agent dispersion is brought into contact with colloidal silica, the aminosilane coupling agent is sufficiently mixed into the colloidal silica while suppressing uneven distribution, and local reactions caused by hydrolysis and condensation polymerization between the aminosilane coupling agents are suppressed, thereby easily suppressing the generation of aggregated particles.

[0091] In the method for producing the amino group-modified colloidal silica according to the present invention, the details of the amino silane coupling agent are as described in the description of the amino group-modified colloidal silica according to the present invention.

[0092] In the method for producing amino group-modified colloidal silica according to the present invention, the content of the aminosilane coupling agent in the aminosilane coupling agent dispersion is preferably 0.5 to 30.0 mass%, more preferably 1.0 to 28.0 mass%, and even more preferably 1.5 to 26.0 mass%.

[0093] In the method for producing amino group-modified colloidal silica according to the present invention, by ensuring that the content of the aminosilane coupling agent in the aminosilane coupling agent dispersion is within the above range, uneven distribution of the aminosilane coupling agent in the dispersion can be suppressed, and when the aminosilane coupling agent is brought into contact with colloidal silica, the aminosilane coupling agent can be highly miscible and: It can be brought into sufficient contact with the silica particles.

[0094] The contact amount of the aminosilane coupling agent is 5 μmol or more and 150 μmol or less, preferably 10 μmol or more and 145 μmol or less, and more preferably 15 μmol or more and 140 μmol or less, per 1 g of colloidal silica (per 1 g of silica particles contained in the colloidal silica) converted into solid content.

[0095] In the method for producing amino group-modified colloidal silica according to the present invention, by ensuring that the contact amount of the aminosilane coupling agent is within the above range, the surfaces of the silica particles can be sufficiently cationized with amino groups, and amino group-modified colloidal silica that exhibits excellent performance when used as abrasive grains for polishing can be easily prepared.

[0096] In the method for producing amino group-modified colloidal silica according to the present invention, when the colloidal silica is brought into contact with the aminosilane coupling agent dispersion, the contact is carried out under a temperature condition of 5°C to 60°C, The contact is preferably carried out under a temperature condition of 6 to 59°C, more preferably under a temperature condition of 7 to 58°C.

[0097] In the method for producing amino group-modified colloidal silica according to the present invention, by contacting the colloidal silica dispersion with the aminosilane coupling agent under the above-mentioned temperature conditions, it is possible to suppress the rapid progress of hydrolysis and condensation polymerization of the aminosilane coupling agent, and to easily suppress the generation of aggregated particles.

[0098] The contact time (reaction time) during the contact treatment is not particularly limited, but is preferably from 5 minutes to 3 hours, more preferably from 7 minutes to 2 hours, and even more preferably from 9 minutes to 1 hour. The pH at which the contact treatment is carried out is not particularly limited, but a pH of 7 or higher and 11 or lower is preferred.

[0099] In the method for producing amino group-modified colloidal silica according to the present invention, the method for bringing colloidal silica into contact with the aminosilane coupling agent dispersion is not particularly limited, and examples thereof include a method in which the aminosilane coupling agent dispersion is added dropwise to the colloidal silica.

[0100] In the method for producing amino group-modified colloidal silica according to the present invention, the reaction liquid obtained by contacting colloidal silica with the aminosilane coupling agent dispersion contains a dispersing medium such as alcohol in addition to water. Therefore, in order to improve long-term storage stability, the dispersing medium such as alcohol in the obtained reaction liquid may be replaced with water, if necessary.

[0101] The method for replacing the dispersion medium with water is not particularly limited, and examples thereof include a method in which a reaction liquid obtained by contacting colloidal silica with an aminosilane coupling agent dispersion is heated, and water is added dropwise in a fixed amount while distilling off the dispersion medium such as alcohol.

[0102] Details of the amino group-modified colloidal silica obtained by the production method according to the present invention are as described above in the description of the amino group-modified colloidal silica according to the present invention.

[0103] According to the present invention, there can be provided a method for producing amino group-modified colloidal silica that can form a polished surface with significantly reduced surface roughness at a high polishing rate. [Example]

[0104] Next, the present invention will be explained in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples in any way.

[0105] Example 1 (1) Colloidal silica (silica sol) preparation process A mother liquor was prepared by mixing 2253 g of pure water, 527 g of 28 mass % ammonia water, and 12391 g of methanol. Next, a raw material solution containing 1,522 g of tetramethoxysilane (TMOS) and 413 g of methanol was injected into the mother liquor at a constant rate over 25 minutes while maintaining the liquid temperature in the reaction system at 20°C, to prepare a silica sol reaction liquid with water and methanol as the dispersion medium. A portion of the obtained silica sol reaction liquid was placed in a flask under normal pressure, and the flask was heated to distill off the solvent, while the remainder of the silica sol reaction liquid was added dropwise to the flask, thereby obtaining a concentrated silica sol liquid having a silica particle concentration of 20 mass % while maintaining the volume of the reaction liquid in the flask constant. Pure water and methanol were added to the obtained silica sol concentrate, and the silica particle concentration was adjusted to 15 mass % and the methanol concentration in the solvent (the proportion of methanol in the solvent) to 65 mass %, thereby obtaining a silica sol (with an average secondary particle diameter of silica particles of 68 nm and a content of coarse particles with a particle diameter of 0.2 μm or more of 4,412,995 particles / mL when the silica particle concentration was 1 mass %). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise to 800 g of the silica sol obtained in (1) an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0106] Example 2 (1) Colloidal silica (silica sol) preparation process A mother liquor was prepared by mixing 2359 g of pure water, 467 g of 28 mass % ammonia water, and 8102 g of methanol. Next, a raw material solution containing 2214 g of tetramethoxysilane (TMOS) and 600 g of methanol was injected into the mother liquor at a constant rate over 240 minutes while maintaining the liquid temperature in the reaction system at 35°C, to prepare a silica sol reaction liquid with water and methanol as the dispersion medium. A portion of the obtained silica sol reaction liquid was placed in a flask under normal pressure, and the flask was heated to distill off the solvent, while the remainder of the silica sol reaction liquid was added dropwise to the flask, thereby obtaining a concentrated silica sol liquid having a silica particle concentration of 20 mass % while maintaining the volume of the reaction liquid in the flask constant. Pure water and methanol were added to the obtained silica sol concentrate, and the silica particle concentration was adjusted to 15% by mass and the methanol concentration in the solvent (the proportion of methanol in the solvent) to 65% by mass, thereby obtaining a silica sol (the average secondary particle diameter of the silica particles was 27 nm, and the content of coarse particles with a particle diameter of 0.2 μm or more contained in the silica particles was 3,312,555 particles / mL when the silica particle concentration was 1% by mass). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion The target product liquid was obtained in the same manner as in Example 1(2), except that the silica sol obtained in (1) was used. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0107] Example 3 (1) Colloidal silica (silica sol) preparation process A mother liquor was prepared by mixing 1571 g of pure water, 316 g of 28 mass % ammonia water, and 8363 g of methanol. Next, 6088 g of tetramethoxysilane (TMOS) and an alkaline solution prepared by mixing 1211 g of pure water and 316 g of 28% by mass aqueous ammonia were injected into the mother liquor at constant rates over 100 minutes while maintaining the liquid temperature in the reaction system at 20°C, thereby preparing a silica sol reaction liquid with water and methanol as the dispersion medium. A portion of the obtained silica sol reaction liquid was placed in a flask under normal pressure, and the flask was heated to distill off the solvent, while the remainder of the silica sol reaction liquid was added dropwise to the flask, thereby obtaining a concentrated silica sol liquid having a silica particle concentration of 20 mass % while maintaining the volume of the reaction liquid in the flask constant. Pure water and methanol were added to the obtained silica sol concentrate, and the silica particle concentration was adjusted to 15 mass % and the methanol concentration in the solvent (the proportion of methanol in the solvent) to 65 mass %, thereby obtaining a silica sol (the average secondary particle diameter of the silica particles was 117 nm, and the content of coarse particles with a particle diameter of 0.2 μm or more contained in the silica particles was 7,321,299 particles / mL when the silica particle concentration was 1 mass %). (2) Contacting colloidal silica with an aminosilane coupling agent dispersion The target product liquid was obtained in the same manner as in Example 1(2), except that the silica sol obtained in (1) was used. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0108] Example 4 (1) Colloidal silica (silica sol) preparation process A silica sol dispersion was obtained in the same manner as in Example 1(1), except that pure water and methanol were added to the obtained silica sol concentrate to adjust the silica particle concentration to 15% by mass and the methanol concentration in the solvent (the proportion of methanol in the solvent) to 50% by mass, thereby obtaining a silica sol (having an average secondary particle diameter of silica particles of 68 nm and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,320,141 particles / mL when the silica particle concentration was 1% by mass). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion The target product liquid was obtained in the same manner as in Example 1(2), except that the silica sol obtained in (1) was used. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0109] Example 5 (1) Colloidal silica (silica sol) preparation process A silica sol was obtained in the same manner as in Example 1(1), except that pure water and methanol were added to the obtained silica sol concentrate to adjust the silica particle concentration to 15% by mass and the methanol concentration in the solvent (the proportion of methanol in the solvent) to 80% by mass, thereby obtaining a silica sol (having an average secondary particle diameter of 68 nm and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,665,421 particles / mL when the silica particle concentration was 1% by mass). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion The target product liquid was obtained in the same manner as in Example 1(2), except that the silica sol obtained in (1) was used. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0110] Example 6 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,481,200 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise an aminosilane coupling agent dispersion (methanol content: 75% by mass) obtained by mixing 3.6 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane to 800 g of the silica sol obtained in (1) over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0111] Example 7 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,571,912 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise to 800 g of the silica sol obtained in (1) an aminosilane coupling agent dispersion (methanol content: 97% by mass) obtained by mixing 38.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0112] Example 8 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,612,932 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise to 800 g of the silica sol obtained in (1) an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane over 10 minutes while maintaining the liquid temperature at 10°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0113] Example 9 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,591,230 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane to 800 g of the silica sol obtained in (1) over 10 minutes while maintaining the liquid temperature at 50°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0114] Example 10 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol reaction liquid containing water and methanol as a dispersion medium was concentrated to a silica particle concentration of 20 mass % to obtain a concentrated silica sol liquid. The obtained silica sol concentrate was then heated to distill off the solvent, while pure water was added dropwise to the flask while keeping the volume of the liquid in the flask constant. The dropwise addition of pure water was stopped when the temperature at the top of the flask reached 100°C or higher and the pH reached 8 or lower. Pure water and methanol were added to the obtained silica sol, and the silica particle concentration was adjusted to 15% by mass, and the methanol concentration in the solvent (the proportion of methanol in the solvent) was adjusted to 5% by mass, thereby obtaining a silica sol (with an average secondary particle diameter of 68 nm and a content of coarse particles with a particle diameter of 0.2 μm or more in the silica particles of 6,618,087 particles / mL when the silica particle concentration was 1% by mass). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise to 800 g of the silica sol obtained in (1) an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0115] Example 11 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,329,755 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltriethoxysilane to 800 g of the silica sol obtained in (1) over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0116] Example 12 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,291,851 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise to 800 g of the silica sol obtained in (1) an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 1. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0117] (Comparative Example 1) (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,101,215 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion To 800 g of the silica sol obtained in (1), 1.2 g of 3-aminopropyltrimethoxysilane (methanol content: 0 mass%) was added dropwise over 10 minutes while maintaining the liquid temperature at 30°C, to obtain a reaction liquid. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 2. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0118] (Comparative Example 2) (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol reaction liquid containing water and methanol as a dispersion medium was concentrated to a silica particle concentration of 20 mass % to obtain a concentrated silica sol liquid. The obtained silica sol concentrate was then heated to distill off the solvent, while pure water was added dropwise to the flask while keeping the volume of the liquid in the flask constant. The dropwise addition of pure water was stopped when the temperature at the top of the flask reached 100°C or higher and the pH reached 8 or lower. Pure water and methanol were added to the obtained silica sol, and the silica particle concentration was adjusted to 15% by mass, and the methanol concentration in the solvent (the proportion of methanol in the solvent) was adjusted to 1% by mass, thereby obtaining a silica sol (with an average secondary particle diameter of 68 nm and a content of coarse particles with a particle diameter of 0.2 μm or more in the silica particles of 6,812,315 particles / mL when the silica particle concentration was 1% by mass). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise to 800 g of the silica sol obtained in (1) an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane over 10 minutes while maintaining the liquid temperature at 30°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and 50 g of pure water was added dropwise to the flask while keeping the volume of the reaction solution in the flask constant, thereby obtaining the desired product solution. The above production conditions are shown in Table 2. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0119] (Comparative Example 3) (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol (having a methanol concentration in the solvent (the proportion of methanol in the solvent) of 65% by mass, an average secondary particle diameter of silica particles of 68 nm, and a content of coarse particles having a particle diameter of 0.2 μm or more contained in the silica particles of 4,320,124 particles / mL when the silica particle concentration was 1% by mass) was obtained. (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise an aminosilane coupling agent dispersion (methanol content: 90% by mass) obtained by mixing 10.8 g of methanol and 1.2 g of 3-aminopropyltrimethoxysilane to 800 g of the silica sol obtained in (1) over 10 minutes while maintaining the liquid temperature at 70°C. That is, 1 part by mass of aminosilane coupling agent was contacted per 100 parts by mass of colloidal silica calculated as solid content (per 100 parts by mass of silica particles contained in colloidal silica) under the above conditions. Thereafter, the resulting reaction solution was heated to distill off the solvent, and while maintaining the volume of the reaction solution in the flask constant, 1300 g of pure water was added dropwise to the flask to obtain the desired product solution. The above production conditions are shown in Table 2. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0120] Comparative Example 4 (1) Colloidal silica (silica sol) preparation process In the same manner as in Example 1(1), a silica sol reaction liquid containing water and methanol as a dispersion medium was concentrated to a silica particle concentration of 20 mass % to obtain a concentrated silica sol liquid. The obtained silica sol concentrate was then heated to distill off the solvent, while pure water was added dropwise to the flask while keeping the volume of the liquid in the flask constant. The dropwise addition of pure water was stopped when the temperature at the top of the flask reached 100°C or higher and the pH reached 8 or lower. Pure water was added to the obtained silica sol to adjust the silica particle concentration to 19.88% by mass, thereby obtaining a silica sol (having an average secondary particle diameter of 68 nm, a content of coarse particles with a particle diameter of 0.2 μm or more contained in the silica particles of 6,749,821 particles / mL when the silica particle concentration was 1% by mass, and a methanol concentration in the solvent (proportion of methanol in the solvent) of less than 0.1% by mass). (2) Contacting colloidal silica (silica sol) with an aminosilane coupling agent dispersion A reaction liquid was obtained by adding dropwise an aminosilane coupling agent dispersion obtained by mixing 771 g of deionized water and 0.771 g of 3-aminopropyltrimethoxysilane to 1,000 g of the silica sol obtained in (1) at a rate of 12 mL / min while maintaining the liquid temperature at 25°C. That is, 0.39 parts by mass of aminosilane coupling agent per 100 parts by mass of colloidal silica (per 100 parts by mass of silica particles contained in colloidal silica) calculated as solid content was contacted under the above conditions. The resulting reaction solution was then stirred at 25°C for 50 minutes to obtain the desired product solution. The above production conditions are shown in Table 2. The resulting product liquid was confirmed to contain silica particles having amino groups fixed to the surface, that is, to be amino group-modified colloidal silica.

[0121] For the amino group-modified colloidal silica obtained in each of the above Examples and Comparative Examples, the pH, the average primary particle size and average secondary particle size of the amino group-modified silica particles, the metal content, and the content (particles / mL) of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles when the silica particle concentration was 1% by mass were determined. The results are shown in Tables 3 and 4.

[0122] The amino group-modified colloidal silica obtained in each of the above Examples and Comparative Examples was used as abrasive grains for polishing, and the removal rate was measured and the polished surface roughness was evaluated by the following methods. The results are shown in Tables 3 and 4.

[0123] <Method for measuring polishing rate and method for evaluating polished surface roughness> The amino group-modified colloidal silica obtained in each of the Examples and Comparative Examples was diluted with ultrapure water to a silica particle concentration of 3.0 mass % to prepare a polishing composition. Using the obtained polishing composition, a 3 cm square silicon wafer having a silicon oxide film formed on its surface was polished under the following conditions. (polishing conditions) Polishing machine: Nanofactor Co., Ltd., NF-300CMP Polishing pad: Nitta DuPont, IC1000TMPad Slurry supply rate: 50 mL / min Head rotation speed: 32 rpm Platen rotation speed: 32 rpm Grinding pressure: 4psi Polishing time: 2 min

[0124] (Method for measuring polishing rate) The film thickness of the silicon wafer before and after polishing under the above polishing conditions was measured using an optical interference film thickness measuring instrument (Ava Spec-2048 manufactured by Avantes), and the polishing rate was calculated from the difference between the measured values ​​and the polishing time. When the polishing rate is calculated using the above method, if the polishing rate is 70 Å / min or more, the polishing property is judged to be good. Abrasiveness was judged to be poor when it was less than 70 Å / min.

[0125] (Method of measuring surface roughness) After polishing under the above polishing conditions, the surface roughness of the polished surface of the silicon wafer was measured using an atomic force microscope under the following conditions. Atomic force microscope: Shimadzu Corporation SPM-9700HT Cantilever: OLYMPUS MICRO CANTILEVER OMCL-AC240TS-R3 Observation mode: Dynamic Scanning range: 3.0 μm square Scanning speed: 1.00Hz Number of observation fields: Five arbitrary fields were observed per polished wafer (observation area per field: 3 μm×3 μm). The root mean square roughness x of each of the five observation fields (five fields) on the polished surface of the wafer i (nm) and calculate the root mean square roughness x in five fields of view using the following formula: i The arithmetic mean value of (nm) was taken as the polished surface roughness Rms (nm). JPEG0007771475000001.jpg25147When the polished surface roughness Rms was measured using the above method, the polishing properties were judged to be good if the polished surface roughness Rms was 10.0 nm or less, and poor if the polished surface roughness was more than 10.0 nm.

[0126] [Table 1]

[0127] [Table 2]

[0128] [Table 3]

[0129] [Table 4]

[0130] As shown in Table 1, in Examples 1 to 12, amino group-modified colloidal silica was prepared by contacting (i) colloidal silica obtained by dispersing silica particles having an average secondary particle size of 10 to 150 nm and a content of coarse particles having a particle size of 0.2 μm or more of 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass in an aqueous medium containing 3% by mass to 95% by mass of alcohol with (ii) an aminosilane coupling agent dispersion containing 70.0% by mass to 99.5% by mass of alcohol, and (iii) a temperature condition of 5°C to 60°C.

[0131] Therefore, as shown in Table 3, the amino group-modified colloidal silica obtained in Examples 1 to 12 had a content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 10,000,000 particles / mL or less when the silica particle concentration was 1% by mass, and it was found that when used to polish semiconductor wafers, a polished surface with significantly reduced surface roughness can be formed at a high polishing rate.

[0132] On the other hand, Table 2 shows that in Comparative Examples 1 to 4, when preparing the amino group-modified colloidal silica, the colloidal silica used had an alcohol content in the aqueous medium outside the specified range (Comparative Examples 2 and 4), the aminosilane coupling agent dispersion had an alcohol content outside the specified range (Comparative Examples 1 and 4), and the contact temperature between the colloidal silica and the aminosilane coupling agent dispersion was outside the specified range (Comparative Example 3).

[0133] For this reason, as shown in Table 4, the amino group-modified colloidal silica obtained in Comparative Examples 1 to 4 all had a content of coarse particles having a particle size of 0.2 μm or more contained in the amino group-modified silica particles of more than 10,000,000 particles / mL when the silica particle concentration was 1% by mass, and it was found that when used to polish semiconductor wafers, it was not possible to form a polished surface with reduced surface roughness. [Industrial Applicability]

[0134] According to the present invention, it is possible to provide an amino group-modified colloidal silica and a method for producing the amino group-modified colloidal silica, which are capable of forming a polished surface with significantly reduced surface roughness at a high polishing rate.

Claims

1. An amino-modified colloidal silica characterized by containing amino-modified silica particles having an average secondary particle diameter of 69 to 150 nm and a content of coarse particles of 0.2 μm or more in diameter of 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass.

2. A method for producing the amino group-modified colloidal silica according to claim 1, comprising: colloidal silica obtained by dispersing silica particles in an aqueous medium containing 3% by mass to 95% by mass of alcohol, the content of coarse particles having a particle size of 0.2 μm or more being 10,000,000 particles / mL or less when the silica particle concentration is 1% by mass; an aminosilane coupling agent dispersion containing 70.0% by mass to 99.5% by mass of alcohol; Contact at temperatures between 5°C and 60°C A method for producing amino group-modified colloidal silica, comprising:

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