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

Abstract

The present invention provides amino group-modified colloidal silica that suppresses the generation of aggregated particles to exhibit long-term stable dispersibility, and enables the high-speed formation of a polished surface with high flatness even when used for polishing semiconductor wafers. The amino group modified colloidal silica is characterized by containing amino group modified silica particles having a pH of 8.50 to 9.50, a Si concentration in the solvent of 150 mass ppm or less, and a content of coarse particles with a particle size of 0.2 μm or more of 10,000,000 particles / mL or less when the silica particle concentration is 1 mass%.

Description

Technology Field

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

[0002] In the semiconductor manufacturing process, the semiconductor wafer is held in a member called a carrier, and the wafer is brought into contact with and rotated by flowing a slurry containing chemicals or abrasive particles, thereby polishing the semiconductor wafer to make it flat.

[0003] In the above polishing treatment method, chemical mechanical polishing (CMP) is also utilized, which uses chemical polishing action by a chemical agent and mechanical polishing action by abrasive particles.

[0004] In chemical mechanical polishing (CMP), it is required that a polished surface be obtained with a further reduced surface roughness of the semiconductor wafer to be polished using abrasive particles.

[0005] Under these circumstances, colloidal silica particles, namely colloidal silica (silica sol), are used as abrasive particles for polishing semiconductor wafers.

[0006] However, colloidal silica is prone to aggregating particles to form aggregated particles, especially when stored for a long period; consequently, when used as abrasive particles for polishing semiconductor wafers, the surface roughness increases, making it difficult to obtain a flat polished surface.

[0007] Accordingly, in order to suppress the aggregation of silica particles and exhibit long-term stable dispersibility, an amino group-modified colloidal silica is proposed in which an aminosilane coupling agent (a silane coupling agent having an amino group) is modified to colloidal silica (see Patent Document 1 (International Publication No. 2018 / 061656 Pamphlet). Prior art literature

[0008] Pamphlet International Release No. 2018 / 061656 The problem to be solved

[0009] According to Patent Document 1, amino group-modified colloidal silica with suppressed formation of aggregated particles is obtained by manufacturing while maintaining a pH higher than the isoelectric point.

[0010] However, as the inventors have carefully examined the present invention, it was found that the amino group-modified colloidal silica obtained by the method described in Patent Document 1 contains a large amount of unreacted aminosilane coupling agent (used when modifying the amino group) remaining in the solvent.

[0011] Furthermore, as the inventors further investigated, it was found that when chemical mechanical polishing is performed using amino group-modified colloidal silica obtained by the method described in Patent Document 1 as abrasive particles, it is difficult to obtain a sufficient polishing speed, possibly because the unreacted aminosilane coupling agent binds to the surface of the object to be polished and inhibits polishing.

[0012] Under these circumstances, the present invention aims to provide an amino group-modified colloidal silica capable of forming a polished surface with high flatness at a high speed, even when used for polishing semiconductor wafers, while suppressing the generation of aggregated particles to exhibit long-term stable dispersibility. means of solving the problem

[0013] In order to solve the above technical problem, the inventors of the present invention conducted a thorough examination and discovered that the problem can be solved by amino group modified colloidal silica containing amino group modified silica particles having a pH of 8.50 to 9.50, a Si concentration in the solvent of 150 mass ppm or less, and a content of coarse particles with a particle size of 0.2 μm or more of 10,000,000 particles / mL or less when the silica particle concentration is 1 mass%, and that the amino group modified colloidal silica can be manufactured by a specific manufacturing method, and based on these findings, the present invention was completed.

[0014] That is, the present invention is,

[0015] (1) pH is 8.50~9.50, and

[0016] The Si concentration in the solvent is 150 mass ppm or less, and

[0017] amino group-modified silica particles comprising a coarse particle content of 0.2 μm or more, which is 10,000,000 particles / mL or less when the silica particle concentration is 1 mass%.

[0018] Amino group-modified colloidal silica characterized by

[0019] (2) The amino group-modified colloidal silica described in (1), wherein the average secondary particle size of the amino group-modified silica particles is 10 to 150 nm,

[0020] (3) A method for producing amino group-modified colloidal silica as described in (1) above,

[0021] With respect to the contact solution obtained by contacting colloidal silica with an aminosilane coupling agent dispersion,

[0022] (i) a first pH control process that maintains the zeta potential at -20.0 mV or less while adjusting the pH to 8.00 or less, and

[0023] (ii) A second pH control process for adjusting the pH to 8.50 to 9.50 by adding a base to the adjustment solution obtained in the first pH control process

[0024] A method for manufacturing amino group-modified colloidal silica characterized by being carried out sequentially

[0025] It is to provide. Effects of the invention

[0026] According to the present invention, it is possible to provide an amino group-modified colloidal silica and a method for manufacturing the same, which suppresses the generation of aggregated particles to exhibit long-term stable dispersibility and can form a high-speed polished surface with high flatness even when used for polishing semiconductor wafers. Specific details for implementing the invention

[0027] First, the amino group-modified colloidal silica according to the present invention will be described.

[0028] The amino group-modified colloidal silica according to the present invention is,

[0029] The pH is 8.50 to 9.50, and

[0030] The Si concentration in the solvent is 150 mass ppm or less, and

[0031] amino group-modified silica particles comprising a coarse particle content of 0.2 μm or more, which is 10,000,000 particles / mL or less when the silica particle concentration is 1 mass%.

[0032] It is characterized by that.

[0033] The amino group-modified colloidal silica according to the present invention comprises amino group-modified silica particles formed by fixing amino groups to silica particles constituting the colloidal silica.

[0034] As for the amino group-modified colloidal silica according to the present invention, it is suitable to include amino group-modified silica particles formed by chemically bonding an aminosilane compound (a silane compound having an amino group) to silica particles constituting the colloidal silica.

[0035] Examples of the above aminosilane compounds include various aminosilane coupling agents.

[0036] As aminosilane coupling agents, for example, 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, etc. are suitable.

[0037] In the amino group-modified colloidal silica according to the present invention, by using the aminosilane coupling agent as an aminosilane compound, Si-O-Si bonds are formed with the colloidal silica through hydrolysis and dehydration condensation reactions, thereby enabling amino group modification (immobilization of amino groups) on the surface of the silica particles constituting the colloidal silica.

[0038] As described above, the amino group-modified colloidal silica constituting the amino group-modified colloidal silica according to the present invention is a collection of amino group-modified silica particles in which amino groups (-NH2) are fixed to silica particles constituting the colloidal silica and dispersed in a solvent, and thus the amino group-modified silica particles have a basic structure derived from the silica particles constituting the colloidal silica.

[0039] In the present application documents, it is confirmed by X-ray photoelectron spectroscopy (XPS) shown below that the amino group-modified colloidal silica comprises amino group-modified silica particles modified by amino groups.

[0040] The measurement sample is centrifuged under conditions of 77,000 G, 5°C, and 90 minutes. The obtained precipitate is dried at 60°C for 12 hours, and the obtained solid is crushed in a mortar using a mortar and pestle, and dried under reduced pressure at 60°C and a gauge pressure of -0.1 MPa or less for 2 hours to prepare a dried powder.

[0041] Using the dried powder, the presence or absence of amino groups on the surface of silica particles is confirmed by X-ray photoelectron spectroscopy under the following conditions.

[0042] Measuring instrument: AXIS-NOVA manufactured by Shimadzu Corporation

[0043] Exposure X-ray: Al-Kα(15kV, 10mA)

[0044] Analysis X-ray spot diameter: 300×700μm

[0045] As described below, a method for preparing colloidal silica can be described as follows: by stirring, for example, tetramethoxysilane (Si(OCH3)4) in an organic solvent containing water, hydrolyzing and dehydrating to form a dimer, and then polymerizing (oligomerizing) this dimer to form spherical silica primary particles in the solvent, and the spherical silica primary particles dispersed in the solvent correspond to colloidal silica.

[0046] In addition, the above colloidal silica includes, together with the silica primary particles, a silica secondary particle to which the silica primary particles have met, and the silica secondary particle is dispersed in a solvent together with the silica primary particles.

[0047] The amino group-modified colloidal silica according to the present invention comprises amino group-modified silica particles in which amino groups are fixed to silica particles dispersed in the colloidal silica.

[0048] The average primary particle size (average diameter of the primary particles of the amino group-modified silica) of the amino group-modified silica particles included in the amino group-modified colloidal silica according to the present invention is not particularly limited, but is preferably 5 nm or more and 120 nm or less.

[0049] The average primary particle size of the amino group-modified silica particles included 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.

[0050] By the fact that the average primary particle size of the amino group-modified silica particles included in the amino group-modified colloidal silica according to the present invention is less than or equal to the above value (upper limit), when polishing is performed using the amino group-modified colloidal silica according to the present invention, a polished surface with superior flatness can be formed.

[0051] The average primary particle size of the amino group-modified silica particles included 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.

[0052] Since the average primary particle size of the amino group-modified silica particles included in the amino group-modified colloidal silica according to the present invention is greater than or equal to the above value (lower limit), when polishing treatment is performed using the amino group-modified colloidal silica according to the present invention, it becomes difficult for particles to aggregate, so a polished surface with superior flatness can be easily formed.

[0053] In addition, in the present application documents, the average primary particle size of the amino group-modified silica particles included in the amino group-modified colloidal silica refers to a value measured by the BET method described below.

[0054] That is, first, 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, and the specific surface area (BET specific surface area) S is measured by the BET method using the obtained measurement sample.

[0055] For nearly spherical particles, the average primary particle size (nm) of amino group-modified silica particles is given by the following formula

[0056] Average primary particle size (nm) of amino group-modified silica particles = 6000 / (BET specific surface area S (m²) 2 / g)×True density(g / cm²) 3 ))

[0057] It can be obtained by, where the true density of the silica particles is 2.2 g / cm³ 3 Based on this, the average primary particle size (nm) of the amino group-modified silica particles is given by the following formula

[0058] Average primary particle size (nm) of amino group-modified silica particles = 2727 / specific surface area (m²) 2 / g)

[0059] It can be obtained by.

[0060] As described above, in that the amino group modified colloidal silica comprises amino group modified silica particles formed by fixing amino groups to silica particles constituting the colloidal silica, the average primary particle size (average diameter of the amino group modified silica primary particles) of the amino group modified silica particles included in the amino group modified colloidal silica is defined as a value calculated by the above method based on the true density of the silica particles as described above.

[0061] The amino group-modified colloidal silica according to the present invention comprises amino group-modified silica secondary particles to which amino group-modified silica primary particles have met.

[0062] The amino group-modified silica secondary particles included in the amino group-modified colloidal silica according to the present invention, together with the amino group-modified silica primary particles included 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 coarse particles (described later) formed by the aggregation of the amino group-modified silica secondary particles or the aminosilane coupling agent.

[0063] The average secondary particle size (average diameter of the amino group-modified silica secondary particles) of the amino group-modified silica particles included in the amino group-modified colloidal silica according to the present invention is preferably 10 to 150 nm, more preferably 15 to 140 nm, and even more preferably 20 to 130 nm.

[0064] Since the average secondary particle size of the amino group-modified silica particles included in the amino group-modified colloidal silica according to the present invention is within the above value range, when polishing treatment is performed using the amino group-modified colloidal silica according to the present invention, a polished surface with superior flatness can be formed.

[0065] In addition, in the present application documents, the average secondary particle size of the amino group-modified silica particles included in the amino group-modified colloidal silica refers to a value measured by the dynamic light scattering method described below.

[0066] That is, first, a 0.3 mass% aqueous citric acid solution is added to the amino group-modified colloidal silica that serves as the measurement sample, and the silica particle concentration is uniformly diluted to 0.8 mass%, and the obtained diluted solution is used as the measurement sample.

[0067] Using the above measurement sample, the average particle size measured by the dynamic light scattering method using the zeta potential, particle size, and molecular weight measurement system “ELSZ-2000S” manufactured by Otsuka Electronics Co., Ltd. is set as the average secondary particle size of the amino group modified silica particles.

[0068] In the amino group-modified colloidal silica according to the present invention, the growth rate of the average secondary particle size of the amino group-modified silica particles constituting the amino group-modified colloidal silica is preferably 5.0% or less, more preferably 4.5% or less, and even more preferably 4.0% or less.

[0069] <Method for Calculating the Increase Rate of Average Secondary Particle Size>

[0070] The concentration of silica particles in the amino group-modified colloidal silica is adjusted to 10 mass%.

[0071] The sample with the above-mentioned silica particle concentration is placed in a fluoropolymer container, sealed, and stored at 25°C for 48 hours.

[0072] The average secondary particle size of amino group-modified silica particles in the amino group-modified colloidal silica before and after the storage of the above sample is measured by the method described above, and the rate of increase in the average secondary particle size is calculated by the following formula.

[0073] Increase rate of average secondary particle size (%) = {(Average secondary particle size of amino-modified silica particles after 48 hours of storage - Average secondary particle size of amino-modified silica particles before storage) / Average secondary particle size of amino-modified silica particles before storage} × 100

[0074] In the present application documents, the growth rate of the average secondary particle size of the amino group-modified silica particles constituting the amino group-modified colloidal silica serves as an indicator of the ease of aggregation of the amino group-modified silica particles constituting the amino group-modified colloidal silica.

[0075] The amino group-modified colloidal silica according to the present invention can easily exhibit stable dispersibility over a long period of time by suppressing the aggregation of amino group-modified silica particles constituting the amino group-modified colloidal silica through the increase rate of the average secondary particle size of the amino group-modified silica particles constituting the amino group-modified colloidal silica being less than or equal to a predetermined value.

[0076] In the amino group-modified colloidal silica according to the present invention, the content of coarse particles with a particle size of 0.2 μm or more included in the amino group-modified silica particles is preferably 10,000,000 particles / mL or less, 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 mass%.

[0077] In the amino group-modified colloidal silica according to the present invention, the content of coarse particles with a particle size of 0.2 μm or more included in the amino group-modified silica particles is less than or equal to the above value (upper limit) when the silica particle concentration in the amino group-modified colloidal silica is set to 1 mass%, thereby suppressing the roughness of the polished surface caused by the presence of coarse particles when chemical mechanical polishing (CMP) is performed using the amino group-modified colloidal silica according to the present invention, so that a polished surface with high flatness can be easily formed.

[0078] In the amino group-modified colloidal silica according to the present invention, the lower limit of the content of coarse particles with a particle size of 0.2 μm or more included 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 with a particle size of 0.2 μm or more included in the amino group-modified silica particles can be 1,000 particles / mL or more when the silica particle concentration is 1 mass%, and it is preferable that it be 0 particles / mL or more.

[0079] In that the amino group-modified colloidal silica according to the present invention has a suppressed content of coarse particles with a particle size of 0.2 μm or more, when chemical mechanical polishing (CMP) is performed using the amino group-modified colloidal silica according to the present invention, a polished surface with high flatness can be easily formed at a high polishing speed.

[0080] In addition, in the present application documents, the content of coarse particles with a particle size of 0.2 μm or more included in the amino group-modified silica particles constituting the amino group-modified colloidal silica refers to a value measured by the number count method particle size distribution measurement method described below.

[0081] Method for Measuring the Content of Coarse Particles with a Particle Size of 0.2 μm or Larger Included in Amino-Modified Silica Particles

[0082] Ultrapure water is added to the amino group-modified colloidal silica to be measured to dilute it so that the silica particle concentration becomes 1.0 mass%.

[0083] 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 the Accusizer FX-nano manufactured by Particle sizing system Inc. under the following measurement conditions.

[0084] <System Setup>

[0085] Stirred Vessel Volume: 13.22mL

[0086] ·Sample Loop Volume: 0.52mL

[0087] ·Autodilution delay time: 3sec.

[0088] ·Normal Speed ​​Flow Rate: 15mL / min

[0089] <Sensor Setup Menu>

[0090] ·FX-Nano HG Minimum Size: 0.15μm

[0091] ·FX-Nano HG Maximum Size: 0.27μm

[0092] ·FX-Nano HG Collection Time: 60sec.

[0093] ·HG Starting Concentration: 8000# / mL

[0094] The pH of the amino group-modified colloidal silica according to the present invention is 8.50 to 9.50.

[0095] The pH of the amino group-modified colloidal silica according to the present invention is preferably 8.50 or higher, more preferably 8.52 or higher, and even more preferably 8.54 or higher.

[0096] By having a pH of the amino group-modified colloidal silica according to the present invention that is greater than or equal to the above value (lower limit), the dispersion stability of the amino group-modified silica particles constituting the amino group-modified colloidal silica according to the present invention is easily improved, and the aggregation of the amino group-modified silica particles during storage or polishing of the amino group-modified colloidal silica according to the present invention is less likely to occur, so that a polished surface with high flatness can be easily formed when used as abrasive particles for polishing.

[0097] In addition, the pH of the amino group-modified colloidal silica according to the present invention is preferably 9.50 or lower, more preferably 9.48 or lower, and even more preferably 9.46 or lower.

[0098] By having the pH of the amino group-modified colloidal silica according to the present invention be lower than or equal to the above value (upper limit), the long-term dispersion stability of the amino group-modified silica particles is improved while their solubility is suppressed, and when used as abrasive particles for polishing, it becomes easier to exhibit excellent polishing properties, thereby making it easy to form a polished surface with high flatness.

[0099] In addition, in the present application, pH refers to a value measured by a pH meter F-2000PI (manufactured by HORIBA, Ltd.) equipped with a pH electrode 9615S-10D (manufactured by HORIBA, Ltd.).

[0100] The content of 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 mass% or more and 50 mass% or less.

[0101] The content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is preferably 1 mass% or more, more preferably 3 mass% or more, and even more preferably 5 mass% or more.

[0102] By having the content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention be greater than or equal to 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 particles for polishing.

[0103] The content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention is preferably 50 mass% or less, more preferably 40 mass% or less, and even more preferably 30 mass% or less.

[0104] By having the content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention be less than or equal to the above value (upper limit), the dispersion stability of the amino group-modified silica particles can be further improved.

[0105] In addition, in the present application documents, the content of amino group-modified silica particles in the amino group-modified colloidal silica according to the present invention refers to a value measured by the following measurement method.

[0106] That is, it refers to the value calculated from the following formula, where 10.0g of amino group-modified colloidal silica is dried on a hot plate at 150℃, then moisture is removed by heat treatment at 800℃ for 1 hour, and the amount of solid obtained is Wg.

[0107] Content of amino group-modified silica particles in amino group-modified colloidal silica (mass%) = (W / 10.0) × 100

[0108] The content of the above silica particles corresponds to the total content of the amino group-modified silica primary particles, amino group-modified silica secondary particles, and coarse particles in the amino group-modified colloidal silica.

[0109] The amino group-modified colloidal silica according to the present invention has a Si concentration in the solvent of 150 mass ppm or less.

[0110] The amino group-modified colloidal silica according to the present invention preferably has a Si concentration in the solvent of 150 mass ppm or less, 145 mass ppm or less, more preferably 140 mass ppm or less, and even more preferably 135 mass ppm or less.

[0111] In the amino group-modified colloidal silica according to the present invention, the Si concentration in the solvent serves as an indicator of the amount of unreacted aminosilane coupling agent remaining in the solvent.

[0112] The amino group-modified colloidal silica according to the present invention can suppress the bonding reaction between the unreacted aminosilane coupling agent and the surface of the object to be polished by limiting the amount of unreacted aminosilane coupling agent remaining in the solvent by having the Si concentration in the solvent below the above value (upper limit).

[0113] As a result, when the amino group-modified colloidal silica according to the present invention is used as abrasive particles for polishing, a polishing surface with high flatness can be formed at high speed while suppressing polishing inhibition caused by unreacted aminosilane coupling agents.

[0114] In the amino group-modified colloidal silica according to the present invention, the lower limit of the Si concentration in the solvent is not particularly limited and is preferably lower, but the content of the amino group-modified colloidal silica according to the present invention may be, for example, 1 mass ppm or more, 5 mass ppm or more, or 10 mass ppm or more.

[0115] As described above, the inventors have investigated that when a semiconductor wafer is polished using amino group-modified colloidal silica, it is difficult to obtain a sufficient polishing rate, possibly because unreacted aminosilane coupling agent used to modify the amino group (-NH2) remains in the solvent and reacts with the surface of the semiconductor wafer to inhibit the polishing process.

[0116] In contrast, in the amino group modified colloidal silica according to the present invention, since the Si concentration in the solvent is limited to a predetermined value or less, even when polishing a semiconductor wafer, high-speed polishing can be performed to form a polished surface with high flatness.

[0117] In addition, in the present application documents, the Si concentration in the solvent of the amino group-modified colloidal silica refers to the silicon atomic concentration calculated by the following method.

[0118] The amino group-modified colloidal silica to be measured is centrifuged under conditions of 77,000 G, 5°C, and 90 minutes.

[0119] The Si concentration (silicon atomic concentration) in the obtained supernatant is measured using the absolute calibration curve method with an inductively coupled plasma emission spectroscopy (ICP-AES) device (IRIS intrepid II manufactured by Thermo Fisher Scientific).

[0120] In addition, the presence of an aminosilane coupling agent in the solvent of the amino group-modified colloidal silica according to the present invention can be confirmed by liquid chromatography-mass spectrometry (LC-MS).

[0121] The amino group-modified colloidal silica according to the present invention may contain metal impurities.

[0122] In the amino group-modified colloidal silica according to the present invention, the metal impurities may include one or more selected from sodium, potassium, iron, aluminum, calcium, magnesium, titanium, nickel, chromium, copper, zinc, lead, silver, manganese, cobalt, etc.

[0123] In the amino group-modified colloidal silica according to the present invention, the total content of metal impurities is preferably 1 mass ppm or less.

[0124] By having a total content of metal impurities of 1 mass ppm or less, the amino group-modified colloidal silica according to the present invention can be suitably used as abrasive particles for polishing electronic materials such as semiconductor wafers.

[0125] In addition, in the present application documents, the content of metal impurities refers to a value measured using an atomic absorption measuring device.

[0126] The amino group-modified colloidal silica according to the present invention can be suitably prepared by the manufacturing method according to the present invention described below.

[0127] According to the present invention, it is possible to provide amino group modified colloidal silica that suppresses the generation of aggregated particles to exhibit long-term stable dispersibility, and can form a high-speed polished surface with high flatness even when used for polishing semiconductor wafers.

[0128] Next, a method for manufacturing amino group-modified colloidal silica according to the present invention will be described.

[0129] The method for manufacturing amino group-modified colloidal silica according to the present invention is,

[0130] A method for producing amino group-modified colloidal silica according to the present invention,

[0131] With respect to the contact solution obtained by contacting colloidal silica with an aminosilane coupling agent dispersion,

[0132] (i) a first pH control process that maintains the zeta potential at -20.0 mV or less while adjusting the pH to 8.00 or less, and

[0133] (ii) The method is characterized by sequentially performing a second pH control process to adjust the pH to 8.50 to 9.50 by adding a base to the adjustment solution obtained in the first pH control process.

[0134] <Contact solution obtained by contacting colloidal silica with an aminosilane coupling agent dispersion>

[0135] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material (raw material colloidal silica) can be appropriately selected from colloidal silica having desired characteristics manufactured by a known manufacturing method, for example, colloidal silica having desired characteristics manufactured by the sol-gel method.

[0136] In the method for manufacturing amino group-modified colloidal silica according to the present invention, when the colloidal silica used as a raw material is colloidal silica produced by the sol-gel method, it can be suitably used because the content of corrosive ions, such as metal impurities or chloride ions that have diffusibility into the semiconductor, is low.

[0137] In the method for manufacturing amino group-modified colloidal silica according to the present invention, when colloidal silica produced by the sol-gel method is used as the raw material colloidal silica, the method for manufacturing said colloidal silica may be conventionally known methods, and specifically, it can be manufactured by using one or more hydrolyzable silicon compounds (e.g., alkoxysilane or a derivative thereof) as raw materials and performing a hydrolysis and condensation reaction.

[0138] As for the above silicon compound, the following general formula (1)

[0139] Si(OR)4(1)

[0140] (In the above general formula (1), the R group is an alkyl group having 1 to 8 carbon atoms.)

[0141] Examples include tetraalkoxysilanes or their derivatives represented by .

[0142] In a silicon compound or derivative thereof represented by general formula (1), the R group is preferably an alkyl group having 1 to 8 carbon atoms, and preferably an alkyl group having 1 to 4 carbon atoms.

[0143] In the silicon compound or derivative thereof represented by general formula (1), the R group may be one or more selected from, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, pentyl group, hexyl group, heptyl group, and octyl group, and one or more selected from methyl group, ethyl group, propyl group, isopropyl group, and butyl group are preferred.

[0144] As a silicon compound represented by general formula (1), 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 is preferred.

[0145] Also, as a derivative of the silicon compound represented by general formula (1), a low condensation product obtained by partially hydrolyzing the silicon compound (tetraalkoxysilane) represented by general formula (1) can be cited.

[0146] As a silicon compound or derivative thereof represented by general formula (1), tetramethoxysilane is preferred because it is easy to control the hydrolysis rate, easy to obtain fine silica particles, and has little residue of unreacted material.

[0147] Silicon compounds or derivatives represented by general formula (1) undergo hydrolysis and condensation in a reaction solvent to become colloidal silica.

[0148] As a dispersion solvent (reaction solvent) used when a silicon compound or its derivative represented by general formula (1) undergoes hydrolysis or condensation, water or an organic solvent containing water may be used.

[0149] The above organic solvent may be one or more selected from hydrophilic organic solvents such as alcohols including methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, and 1,4-butanediol, and ketones including acetone and methyl ethyl ketone.

[0150] Among these organic solvents, it is particularly desirable to use alcohols such as methanol, ethanol, and isopropanol, and from the perspective of post-treatment of the reaction solvent, it is more desirable to use alcohols having an alkyl group such as the alkyl group (R group) of the silicon compound of the raw material (e.g., methanol for tetramethoxysilane).

[0151] The amount of the above organic solvent used is not particularly limited, but it is preferred to be 5 moles or more and 50 moles or less per mole of silicon compound or derivative represented by general formula (1).

[0152] If the amount of the above organic solvent used is less than 5 moles per mole of the silicon compound or its derivative represented by general formula (1), it may be difficult to achieve compatibility with the silicon compound represented by general formula (1), and if it exceeds 50 moles per mole of the silicon compound or its derivative represented by general formula (1), the manufacturing efficiency may decrease.

[0153] The amount of water added to the silicon compound or its derivative represented by general formula (1) is not particularly limited and is sufficient as long as it is the amount required for the hydrolysis of the silicon compound represented by general formula (1), and is preferably about 2 to 200 moles per mole of the silicon compound or its derivative represented by general formula (1).

[0154] In addition, when an organic solvent containing water is added to a silicon compound or its derivative represented by general formula (1), the amount of water mixed into the organic solvent greatly affects the particle size of the colloidal silica formed.

[0155] If the amount of water added relative to the amount of organic solvent added is increased, the particle size of the resulting colloidal silica can be made relatively large, and if the amount of water added relative to the amount of organic solvent added is decreased, the particle size of the resulting colloidal silica can be made relatively small.

[0156] In this way, by changing the mixing ratio of water and organic solvent, the particle size of the resulting colloidal silica can be arbitrarily adjusted.

[0157] For the reaction solvent of the hydrolysis condensation reaction of silicon compounds to obtain colloidal silica, it is desirable to adjust the reaction solvent to alkaline in the presence of an alkaline catalyst.

[0158] By the above adjustment, the reaction solvent is preferably controlled to a pH greater than 8.00 and less than or equal to 11.00, more preferably between 8.50 and 10.50, so that colloidal silica can be rapidly formed.

[0159] As for the above alkaline catalyst, from the perspective of preventing the incorporation of impurities, one or more selected from organic amines or ammonia are preferred, and in particular, one or more selected from ethylenediamine, diethylenetriamine, triethylenetetraamine, 3-ethoxypropylamine, ammonia, urea, ethanolamine, and tetramethylammonium hydroxide are more preferred.

[0160] To hydrolyze and condense a silicon compound in a reaction solvent, a silicon compound represented by general formula (1) or a derivative thereof is added to a solvent containing water, and the mixture is stirred under temperature conditions of typically 0°C or higher and 100°C or lower, preferably 0°C or higher and 50°C or lower.

[0161] By stirring a silicon compound in a solvent containing water, a hydrolysis and dehydration condensation reaction of the silicon compound represented by general formula (1) or its derivative proceeds, and first, the silicon compound represented by general formula (1) or its derivative undergoes dehydration condensation to form a dimer, and this dimer is polymerized (oligomerized) to form spherical silica primary particles in the solvent, thereby obtaining colloidal silica in which the silica primary particles are dispersed in the solvent.

[0162] Among the above colloidal silica, secondary particles (silica secondary particles) formed by the contact of primary silica particles are also included.

[0163] Colloidal silica with uniform silica particle size can be obtained by hydrolyzing and condensing a silicon compound while stirring it in a solvent containing water.

[0164] The colloidal silica obtained by the above hydrolysis and condensation reaction (sol-gel method) can be used as a raw material colloidal silica in the manufacturing method according to the present invention by appropriately adjusting the concentration.

[0165] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material comprises an aqueous medium that serves as a solvent.

[0166] The above aqueous medium may be a dispersion solvent used during the preparation of colloidal silica, or it may be one added separately after the preparation of the raw material colloidal silica.

[0167] In addition, the above aqueous medium may be the same as the dispersion solvent used in the preparation of colloidal silica.

[0168] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material preferably has a pH greater than 8.00 and 11.00 or less, and more preferably has a pH of 8.50 or more and 10.50 or less.

[0169] In addition, in the method for manufacturing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material preferably has an average secondary particle size of silica particles of 150 nm or less, more preferably 145 nm or less, and even more preferably 140 nm or less.

[0170] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the average secondary particle size of the silica particles constituting the raw material colloidal silica is less than or equal to the above value (upper limit), so that when the amino group-modified colloidal silica obtained by the method according to the present invention is used for polishing treatment, a polished surface with superior flatness can be formed.

[0171] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the average secondary particle size of the silica particles constituting the colloidal silica used as a raw material is preferably 10 nm or more, more preferably 12 nm or more, even more preferably 15 nm or more, and even more preferably 20 nm or more.

[0172] Since the average secondary particle size of the silica particles constituting the colloidal silica is greater than or equal to the above value (lower limit), when polishing is performed using the amino group modified colloidal silica obtained by the manufacturing method according to the present invention, it becomes difficult for the silica particles to aggregate, so a polished surface with superior flatness can be formed.

[0173] In addition, in the present application, the average secondary particle size of the silica particles constituting the colloidal silica can be measured in the same way as the method for measuring the average secondary particle size of the silica particles in the amino group-modified colloidal silica described above.

[0174] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the colloidal silica used as a raw material preferably has a coarse particle content of 0.2 μm or more contained in the silica particles that is 10,000,000 particles / mL or less when the silica particle concentration is 1 mass%, more preferably 9,800,000 particles / mL or less, and even more preferably 9,600,000 particles / mL or less.

[0175] In the amino group-modified colloidal silica according to the present invention, the content of coarse particles with a particle size of 0.2 μm or more included in the silica particles constituting the raw material colloidal silica is less than or equal to the above value (upper limit) when the silica particle concentration is 1 mass%, so that when chemical mechanical polishing (CMP) is performed using the amino group-modified colloidal silica obtained by the manufacturing method according to the present invention, the roughness of the polished surface caused by the presence of coarse particles is suppressed, and a polished surface with high flatness can be easily formed.

[0176] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the lower limit of the content of coarse particles with a particle size of 0.2 μm or more included in the silica particles constituting the raw material colloidal silica is not particularly limited, but the content of coarse particles with a particle size of 0.2 μm or more included in the silica particles constituting the colloidal silica can be 1,000 particles / mL or more when the silica particle concentration is 1 mass%, and it is preferable that it be 0 particles / mL or more.

[0177] In addition, in the present application documents, the content of coarse particles with a particle size of 0.2 μm or more contained in the silica particles constituting the raw material colloidal silica can be measured by the same method as the measurement method for the content of coarse particles with a particle size of 0.2 μm or more contained in the amino group modified silica particles constituting the amino group modified colloidal silica described above.

[0178] In the method for manufacturing amino group-modified colloidal silica according to the present invention, a contact solution obtained by contacting the colloidal silica, which serves as a raw material, with an aminosilane coupling agent dispersion is used.

[0179] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the details of the aminosilane coupling agent are as described in the description of the amino group-modified colloidal silica according to the present invention.

[0180] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the content ratio 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%.

[0181] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the content ratio of the aminosilane coupling agent in the aminosilane coupling agent dispersion is within the above range, thereby suppressing the uneven distribution of the aminosilane coupling agent in the dispersion, so that when contacted with colloidal silica, it can be sufficiently contacted with silica particles under high miscibility.

[0182] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the dispersion solvent (reaction solvent) used in the aminosilane coupling agent dispersion may be water or an organic solvent containing water.

[0183] The above organic solvent may be one or more selected from hydrophilic organic solvents such as alcohols including methanol, ethanol, isopropanol, n-butanol, t-butanol, pentanol, ethylene glycol, propylene glycol, and 1,4-butanediol, and ketones including acetone and methyl ethyl ketone.

[0184] Among these organic solvents, it is particularly desirable to use alcohols such as methanol, ethanol, and isopropanol.

[0185] The contact amount of the aminosilane coupling agent is preferably 5 μmol or more and 150 μmol or less per 1 g of colloidal silica (per 1 g of silica particles contained in colloidal silica) converted to solid content, more preferably 10 μmol or more and 145 μmol or less, and even more preferably 15 μmol or more and 140 μmol.

[0186] In the method for manufacturing amino group-modified colloidal silica according to the present invention, by having the contact amount of the aminosilane coupling agent within the above range, the surface of the silica particles can be sufficiently cationized by the amino group, and amino group-modified colloidal silica that exhibits excellent performance when used as abrasive particles can be easily prepared.

[0187] In the method for manufacturing amino group-modified colloidal silica according to the present invention, when contacting the raw material colloidal silica with an aminosilane coupling agent dispersion, it is preferable to contact them under temperature conditions of 5°C to 60°C, under temperature conditions of 6°C to 59°C, and more preferable to contact them under temperature conditions of 7°C to 58°C.

[0188] In the method for manufacturing amino group-modified colloidal silica according to the present invention, by contacting the colloidal silica dispersion with the aminosilane coupling agent under the above temperature conditions, the rapid progress of hydrolysis and polycondensation reactions of the aminosilane coupling agent can be suppressed, thereby easily suppressing the generation of aggregated particles.

[0189] The contact time (reaction time) when performing the above contact treatment is not particularly limited, but it is preferably 5 minutes or more and 3 hours or less, more preferably 7 minutes or more and 2 hours or less, and even more preferably 9 minutes or more and 1 hour or less.

[0190] The pH at which the above contact treatment is performed is not particularly limited, but a pH of 7.00 or higher and 11.00 or lower is preferred.

[0191] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the method of contacting the colloidal silica with an aminosilane coupling agent dispersion is not particularly limited, and for example, a method of dropping an aminosilane coupling agent dispersion onto the colloidal silica may be cited.

[0192] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the contact solution obtained by contacting the colloidal silica with an aminosilane coupling agent dispersion has a pH that is typically 8.10 to 11.00, 8.30 to 10.50, and more preferably 8.50 to 10.00.

[0193] <1st pH Control Process>

[0194] In the method for manufacturing amino group-modified colloidal silica according to the present invention, for a contact solution obtained by contacting colloidal silica with an aminosilane coupling agent dispersion, (i) a first pH control process is performed to adjust the pH to 8.00 or lower while maintaining the zeta potential at -20.0 mV or lower.

[0195] In the method for manufacturing amino group-modified colloidal silica according to the present invention, in the first pH control process, for the contact solution obtained by contacting the colloidal silica with an aminosilane coupling agent dispersion, it is preferable to adjust the pH to 8.00 or lower, and to adjust the pH to 7.96 or lower, and more preferable to adjust the pH to 7.92 or lower.

[0196] In the method for manufacturing amino group-modified colloidal silica according to the present invention, in the first pH control process, the pH of the contact solution obtained by contacting the colloidal silica with the aminosilane coupling agent dispersion is adjusted to be lower than or equal to the above value (upper limit).

[0197] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the contact solution obtained by contacting the colloidal silica with an aminosilane coupling agent dispersion typically has a pH greater than 8.00, so the first pH control process corresponds to a process of lowering the pH of the contact solution to a predetermined range.

[0198] In the method for manufacturing amino group-modified colloidal silica according to the present invention, by adjusting the pH of the contact solution in the first pH control process as described above, the solubility of the aminosilane coupling agent in the contact solution is suppressed (the solubility of the aminosilane coupling agent in the solvent is reduced), and the reactivity of the aminosilane coupling agent to the silica particles constituting the colloidal silica can be improved.

[0199] As a result, even when the amino group-modified colloidal silica obtained from being able to reduce the amount of aminosilane coupling agent remaining in the solvent is used as abrasive particles for polishing, polishing inhibition caused by the bonding of unreacted aminosilane coupling agent remaining in the solvent with the surface of the object to be polished can be effectively suppressed.

[0200] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the pH adjustment of the contact solution obtained by contacting the colloidal silica with the aminosilane coupling agent dispersion in the first pH control process is performed while maintaining the zeta potential at -20.0 mV or lower, preferably while maintaining the zeta potential at -20.2 mV or lower, and more preferably while maintaining the zeta potential at -20.4 mV or lower.

[0201] Zeta potential refers to the potential difference that occurs at the interface between a solid and a liquid when they are in contact and undergo relative motion. As the absolute value of the zeta potential increases, the repulsion between particles becomes stronger, increasing particle stability; conversely, as the absolute value of the zeta potential approaches zero, particles become more prone to aggregation.

[0202] In the method for manufacturing amino group-modified colloidal silica according to the present invention, by controlling the zeta potential in the first pH control process as described above, the dispersion stability of the amino group-modified silica particles constituting the amino group-modified colloidal silica can be improved, and the aggregation thereof can be effectively suppressed.

[0203] In the method for manufacturing amino group-modified colloidal silica according to the present invention,

[0204] In the first pH control process, when adjusting the pH of the contact solution, if the pH is set too low, the dispersion stability of the amino group-modified silica particles constituting the amino group-modified colloidal silica is reduced, making it difficult to suppress aggregation.

[0205] The method for manufacturing amino group-modified colloidal silica according to the present invention can easily maintain the dispersion stability of amino group-modified silica particles in the contact solution during the first pH control process by defining the zeta potential in the first pH control process as described above, instead of defining the lower limit of the pH of the adjustment solution obtained in the first pH control process.

[0206] In addition, in the present application documents, the zeta potential refers to the value obtained when the silica particle concentration in the measurement sample is diluted with a 10 mM aqueous sodium chloride solution so that the concentration is 1 mass%, and the obtained diluted solution is measured using a zeta potential, particle size, and molecular weight measurement system (ELS-Z manufactured by Otsuka Electronics Co., Ltd.).

[0207] In the method for manufacturing amino group-modified colloidal silica according to the present invention, the method of controlling the pH in the first pH control process is not particularly limited.

[0208] As described above, in the method for manufacturing amino group-modified colloidal silica according to the present invention, the contact solution obtained by contacting the colloidal silica with an aminosilane coupling agent dispersion typically has a pH greater than 8.0 and often contains a dispersion medium such as alcohol in addition to water, so a method of adjusting the pH by replacing the dispersion medium such as alcohol in the obtained reaction solution with water can be cited.

[0209] The method of replacing the above dispersion medium with water is not particularly limited, and for example, a method of adding a certain amount of water dropwise while distilling off the dispersion medium, such as alcohol, by heating the reaction solution obtained by contacting colloidal silica with an aminosilane coupling agent dispersion can be cited.

[0210] <2nd pH Control Process>

[0211] In the method for manufacturing amino group-modified colloidal silica according to the present invention, (ii) a second pH control process is performed to adjust the pH to 8.50 to 9.50 by adding a base to the adjustment solution obtained in the first pH control process.

[0212] In the method for manufacturing amino group-modified colloidal silica according to the present invention, in the second pH control process, a base is added to the adjustment solution obtained in the first pH control process to adjust the pH to 8.50 to 9.50, and it is preferable to adjust the pH to 8.52 to 9.48, and more preferable to adjust the pH to 8.54 to 9.46.

[0213] In the method for manufacturing amino group-modified colloidal silica according to the present invention, as a base used in the second pH control process, one or more selected from organic amines or ammonia are preferred from the viewpoint of preventing the incorporation of impurities, and one or more selected from ethylenediamine, diethylenetriamine, triethylenetetraamine, ammonia, urea, ethanolamine, and tetramethylammonium hydroxide are more preferred.

[0214] In the method for manufacturing amino group-modified colloidal silica according to the present invention, in the second pH control process, a base is added to the adjustment solution obtained in the first pH control process to raise the pH to 8.50 to 9.50, thereby improving the dispersion stability of the amino group-modified silica particles constituting the amino group-modified colloidal silica and easily improving long-term storage stability while suppressing aggregation.

[0215] The details of the amino group-modified colloidal silica obtained by the manufacturing method according to the present invention are as described in the description of the amino group-modified colloidal silica according to the present invention.

[0216] According to the present invention, a method for producing amino group-modified colloidal silica can be provided, which suppresses the generation of aggregated particles to exhibit long-term stable dispersibility and can form a high-speed polished surface with high flatness even when used for polishing semiconductor wafers.

[0217] Examples

[0218] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited in any way by the following examples.

[0219] (Example 1)

[0220] (1) Preparation process of colloidal silica (silica sol)

[0221] 2253g of pure water, 527g of 28 mass% ammonia water, and 12391g of methanol were mixed to prepare a mother liquor (water concentration 17.4 mass%, ammonia concentration 0.97 mass%).

[0222] Next, a raw material solution containing 1522 g of tetramethoxysilane (TMOS) and 413 g of methanol was injected 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 solution using water and methanol as dispersion media.

[0223] A portion of the obtained silica sol reaction solution was injected into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, while the remainder of the silica sol reaction solution was added dropwise into the flask, and while maintaining the volume of the reaction solution in the flask constant, a silica sol concentrate (average secondary particle size of silica particles 68 nm, pH 9.41) was obtained by concentrating the silica particles to a concentration of 20 mass%.

[0224] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0225] (1) A reaction solution (zeta potential -51.5 mV) was obtained by adding a mixture of 14.4 g of methanol and 1.6 g of 3-aminopropyltrimethoxysilane (methanol concentration 90 mass%) to 800 g of silica sol concentrate obtained in the process over 10 minutes while maintaining the liquid temperature at 30℃.

[0226] That is, by contacting 1 part by mass of an aminosilane coupling agent per 100 parts by mass of colloidal silica converted to solid content (per 100 parts by mass of silica particles contained in the colloidal silica) under the above conditions, a reaction solution (pH 9.61) was obtained.

[0227] (3) 1st pH control process

[0228] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.42, zeta potential -32.0mV).

[0229] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0230] (4) 2nd pH control process

[0231] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.10, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0232] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0233] The above amino group-modified colloidal silica had a pH of 9.05, a Si concentration of 87 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 68 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 7,754,231 particles / mL when the silica particle concentration was 1 mass%.

[0234] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0235] (Example 2)

[0236] (1) Preparation process of colloidal silica (silica sol)

[0237] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0238] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0239] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0240] (3) 1st pH control process

[0241] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1100g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.92, zeta potential -41.2mV).

[0242] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0243] (4) 2nd pH control process

[0244] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.05, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0245] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0246] The above amino group-modified colloidal silica had a pH of 9.03, a Si concentration of 90 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 68 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 6,259,124 particles / mL when the silica particle concentration was 1 mass%.

[0247] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0248] (Example 3)

[0249] (1) Preparation process of colloidal silica (silica sol)

[0250] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0251] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0252] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0253] (3) 1st pH control process

[0254] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1800g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 6.87, zeta potential -20.5mV).

[0255] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0256] (4) 2nd pH control process

[0257] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.19, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0258] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0259] The above amino group-modified colloidal silica had a pH of 9.16, a Si concentration of 84 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 67 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 8,238,512 particles / mL when the silica particle concentration was 1 mass%.

[0260] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0261] (Example 4)

[0262] (1) Preparation process of colloidal silica (silica sol)

[0263] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0264] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0265] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0266] (3) 1st pH control process

[0267] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.54, zeta potential -30.5mV).

[0268] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0269] (4) 2nd pH control process

[0270] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 8.62, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0271] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0272] The above amino group-modified colloidal silica had a pH of 8.61, a Si concentration of 72 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 67 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 8,072,412 particles / mL when the silica particle concentration was 1 mass%.

[0273] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0274] (Example 5)

[0275] (1) Preparation process of colloidal silica (silica sol)

[0276] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0277] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0278] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0279] (3) 1st pH control process

[0280] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.48, zeta potential -31.2mV).

[0281] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0282] (4) 2nd pH control process

[0283] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.44, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0284] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0285] The above amino group-modified colloidal silica had a pH of 9.41, a Si concentration of 115 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 69 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 5,489,239 particles / mL when the silica particle concentration was 1 mass%.

[0286] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0287] (Example 6)

[0288] (1) Preparation process of colloidal silica (silica sol)

[0289] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0290] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0291] (1) A reaction solution (zeta potential -53.2 mV) was obtained by adding a mixture of 14.4 g of methanol and 1.6 g of 3-aminopropyltriethoxysilane (methanol concentration 90 mass%) to 800 g of silica sol concentrate obtained in the process over 10 minutes while maintaining the liquid temperature at 30℃.

[0292] That is, by contacting 1 part by mass of an aminosilane coupling agent per 100 parts by mass of colloidal silica converted to solid content (per 100 parts by mass of silica particles contained in the colloidal silica) under the above conditions, a reaction solution (pH 9.53) was obtained.

[0293] (3) 1st pH control process

[0294] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.31, zeta potential -35.1mV).

[0295] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0296] (4) 2nd pH control process

[0297] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.12, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0298] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0299] The above amino group-modified colloidal silica had a pH of 9.10, a Si concentration of 80 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 68 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 6,817,240 particles / mL when the silica particle concentration was 1 mass%.

[0300] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0301] (Example 7)

[0302] (1) Preparation process of colloidal silica (silica sol)

[0303] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0304] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0305] (1) A reaction solution (zeta potential -49.2 mV) was obtained by adding a mixture of 14.4 g of methanol and 1.6 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (methanol concentration 90 mass%) to 800 g of silica sol concentrate obtained in the process over 10 minutes while maintaining the liquid temperature at 30℃.

[0306] That is, by contacting 1 part by mass of an aminosilane coupling agent per 100 parts by mass of colloidal silica converted to solid content (per 100 parts by mass of silica particles contained in the colloidal silica) under the above conditions, a reaction solution (pH 9.72) was obtained.

[0307] (3) 1st pH control process

[0308] (2) The reaction solution obtained from the process was injected into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.51, zeta potential -28.7mV).

[0309] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0310] (4) 2nd pH control process

[0311] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.08, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0312] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0313] The above amino group-modified colloidal silica had a pH of 9.04, a Si concentration of 85 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 67 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 7,701,856 particles / mL when the silica particle concentration was 1 mass%.

[0314] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0315] (Comparative Example 1)

[0316] (1) Preparation process of colloidal silica (silica sol)

[0317] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% was obtained.

[0318] Afterwards, the obtained silica sol concentrate was heated to remove the solvent by distillation, while maintaining a constant volume of liquid in the flask, and pure water was added dropwise into the flask. When the top temperature of the flask was 100°C or higher and the pH was 8.00 or lower, the addition of pure water was stopped, and a silica sol with a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 7.72) was obtained.

[0319] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0320] (1) A reaction solution (zeta potential -34.2 mV) was obtained by adding a mixture of 14.4 g of methanol and 1.6 g of 3-aminopropyltrimethoxysilane (methanol concentration 90 mass%) to 800 g of silica sol obtained in the process over 10 minutes while maintaining the liquid temperature at 30℃.

[0321] That is, by contacting 1 part by mass of an aminosilane coupling agent per 100 parts by mass of colloidal silica (per 100 parts by mass of silica particles contained in the colloidal silica) converted to solid content under the above conditions, a reaction solution (pH 8.21) was obtained.

[0322] (3) pH control process

[0323] (2) After heating the reaction solution obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.37, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0324] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0325] The above amino group-modified colloidal silica had a pH of 9.35, a Si concentration of 285 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 67 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 8,659,112 particles / mL when the silica particle concentration was 1 mass%.

[0326] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0327] (Comparative Example 2)

[0328] (1) Preparation process of colloidal silica (silica sol)

[0329] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0330] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0331] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0332] (3) 1st pH control process

[0333] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 800g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 8.58, zeta potential -44.5mV).

[0334] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0335] (4) 2nd pH control process

[0336] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.35, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0337] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0338] The above amino group-modified colloidal silica had a pH of 9.31, a Si concentration of 185 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 69 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 7,681,922 particles / mL when the silica particle concentration was 1 mass%.

[0339] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0340] (Comparative Example 3)

[0341] (1) Preparation process of colloidal silica (silica sol)

[0342] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0343] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0344] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0345] (3) 1st pH control process

[0346] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 2100g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 6.32, zeta potential -7.8mV).

[0347] (4) 2nd pH control process

[0348] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 9.29, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0349] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0350] The above amino group-modified colloidal silica had a pH of 9.26, a Si concentration of 89 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 72 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 43,456,912 particles / mL when the silica particle concentration was 1 mass%.

[0351] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0352] (Comparative Example 4)

[0353] (1) Preparation process of colloidal silica (silica sol)

[0354] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0355] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0356] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0357] (3) 1st pH control process

[0358] (2) The reaction solution obtained in the process was injected into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300 parts by mass of pure water were added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.57, zeta potential -30.4 mV).

[0359] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0360] (4) 2nd pH control process

[0361] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 8.21, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0362] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0363] The above amino group-modified colloidal silica had a pH of 8.20, a Si concentration of 65 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 71 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 29,105,261 particles / mL when the silica particle concentration was 1 mass%.

[0364] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0365] (Comparative Example 5)

[0366] (1) Preparation process of colloidal silica (silica sol)

[0367] By performing the same treatment as process (1) of Example 1, a silica sol concentrate concentrated to a silica particle concentration of 20 mass% (average secondary particle diameter of silica particles 68 nm, pH 9.41) was obtained.

[0368] (2) Contact process between colloidal silica (silica sol) and aminosilane coupling agent dispersion

[0369] By performing the same treatment as process (2) of Example 1, a reaction solution (pH 9.61, zeta potential -51.5mV) was obtained.

[0370] (3) 1st pH control process

[0371] (2) The reaction solution obtained from the process was poured into a flask under atmospheric pressure, and the flask was heated to remove the solvent by distillation, and 1300g of pure water was added dropwise into the flask while maintaining the volume of the reaction solution in the flask constant, and the solvent was replaced with water to obtain a silica water dispersion (pH 7.61, zeta potential -33.1mV).

[0372] Throughout the entire process of replacing the solvent with water, the zeta potential in the reaction solution was maintained at -20.0 mV or lower.

[0373] (4) 2nd pH control process

[0374] (3) After cooling the silica aqueous dispersion obtained from the process to 70°C, 28 mass% ammonia water was added to raise the pH to 10.02, and then the solution was maintained at 70°C for 24 hours to obtain the desired product.

[0375] It was confirmed that the obtained product contained silica particles with amino groups fixed on the surface, that is, amino group modified colloidal silica.

[0376] The above amino group-modified colloidal silica had a pH of 9.98, a Si concentration of 221 mass ppm in the solvent, an average secondary particle size of the amino group-modified silica particles of 73 nm, and a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles of 38,120,412 particles / mL when the silica particle concentration was 1 mass%.

[0377] The above manufacturing conditions are shown in Table 1, and the physical properties of the obtained amino group-modified colloidal silica are shown in Table 2.

[0378] The dispersion stability of the amino group-modified silica particles constituting the amino group-modified colloidal silica obtained in each of the above examples and comparative examples was evaluated by the following method. The results are shown in Table 2.

[0379] <Variance Stability Evaluation Method>

[0380] The increase rate of the average secondary particle size of the amino group-modified silica particles in the amino group-modified colloidal silica obtained in each of the above examples or comparative examples was calculated by the method described above.

[0381] In that state, regarding dispersion stability, if the growth rate of the average secondary particle size exceeds 5.0%, it is evaluated that the dispersion stability is poor because the aggregation of the amino group-modified silica particles proceeds, and if the growth rate of the secondary particle size is 5.0% or less, it is evaluated that the dispersion stability of the amino group-modified silica particles is good.

[0382] The amino group-modified colloidal silica obtained in each of the above examples and comparative examples was used as abrasive particles for polishing, and the surface roughness of the polished surface was evaluated by the following method. The results are shown in Table 2.

[0383] Evaluation Method for Grinding Speed ​​and Surface Roughness

[0384] A polishing composition was prepared by adding ultrapure water to the amino group-modified colloidal silica obtained in each example and comparative example, and diluting it to a silica particle concentration of 3.0 mass%.

[0385] Using the obtained polishing composition, a silicon wafer measuring 3 cm by 3 cm with a silicon oxide film formed on its surface was polished under the following conditions.

[0386] (Grinding conditions)

[0387] Grinder: Manufactured by NANO FACTOR, NF-300CMP

[0388] Polishing Pad: Manufactured by NITTA DuPont Incorporated, IC1000TMPad

[0389] Slurry feed rate: 50 mL / min

[0390] Head rotation speed: 32 rpm

[0391] Platen rotation speed: 32 rpm

[0392] Grinding pressure: 4 psi

[0393] Polishing time: 2 min

[0394] (Method for measuring grinding speed)

[0395] 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 (Avantes-manufactured Ava Spec-2048), and the polishing speed was calculated from the difference and the polishing time.

[0396] When calculating the polishing speed using the above method, it was determined that the polishability was good when the polishing speed was 70 Å / min or higher, and that the polishability was poor when the polishing speed was less than 70 Å / min.

[0397] (Method for measuring surface roughness)

[0398] For the silicon wafer polished under the above polishing conditions, the surface roughness of the polished surface was measured using an atomic force microscope under the following conditions.

[0399] Atomic Force Microscope: SPM-9700HT manufactured by Shimadzu Corporation

[0400] Cantilever: Manufactured by OLYMPUS CORPORATION, MICRO CANTILEVER OMCL-AC240TS-R3

[0401] Observation Mode: Dynamic

[0402] Scanning range: 3.0μm x 3.0μm

[0403] Scan rate: 1.00Hz

[0404] Number of fields of view: 5 random fields of view were observed per wafer after polishing (observation range per field of view: 3μm × 3μm).

[0405] In five observation fields (5 fields) on the wafer polished surface, for each, root mean square illuminance x i Measure (nm), and the root mean square illuminance x in 5 fields of view calculated by the following formula i The arithmetic mean of (nm) was set as the surface roughness Rms(nm).

[0406]

[0407] When measuring the surface roughness Rms using the above method, it was determined that the polishability was good when the surface roughness Rms was 10.0 nm or less, and that the polishability was poor when the surface roughness exceeded 10.0 nm.

[0408]

[0409]

[0410] As shown in Table 1, in Examples 1 to 7, amino group-modified colloidal silica is prepared by sequentially performing (i) a first pH control process to adjust the pH to 8.00 or lower while maintaining the zeta potential at -20.0 mV or lower, and (ii) a second pH control process to adjust the pH to 8.50 to 9.50 by adding a base to the adjusted solution obtained from the first pH control process.

[0411] As a result, as shown in Table 2, the amino group-modified colloidal silica obtained in Examples 1 to 7 has a pH of 8.50 to 9.50, a Si concentration in the solvent of 150 mass ppm or less, and a content of coarse particles with 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 is 1 mass%.

[0412] In this case, as shown in Table 2, the amino group-modified colloidal silica obtained in Examples 1 to 7 has a low growth rate of the average secondary particle size of the amino group-modified silica particles, which suppresses the formation of aggregated particles and exhibits stable dispersibility over a long period, and can form a polished surface with high flatness even when used for polishing semiconductor wafers.

[0413] Meanwhile, from Table 1, in Comparative Examples 1 to 5, when preparing the amino group-modified colloidal silica, the first pH control process is not performed (Comparative Example 1), the pH or zeta potential in the first pH control process is outside the predetermined range (Comparative Example 2, Comparative Example 3), or the pH in the second pH control process is outside the predetermined range (Comparative Example 4, Comparative Example 5).

[0414] As a result, as shown in Table 2, the amino group-modified colloidal silica obtained in Comparative Examples 1 to 5 has a pH outside the specified range (Comparative Example 4, Comparative Example 5), a Si concentration in the solvent exceeds a specified value (Comparative Example 1, Comparative Example 2, and Comparative Example 5), or a content of coarse particles with a particle size of 0.2 μm or more contained in the amino group-modified silica particles exceeds a specified value (Comparative Examples 3 to 5).

[0415] In this case, as shown in Table 2, it can be seen that the amino group-modified colloidal silica obtained in Comparative Examples 1 to 5 cannot exhibit stable dispersibility for a long period of time due to the high growth rate of the average secondary particle size of the amino group-modified silica particles (Comparative Example 4, Comparative Example 5), or when used for polishing semiconductor wafers, it cannot form a polished surface at high speed (Comparative Example 1, Comparative Example 2, and Comparative Example 5), or cannot form a polished surface with high flatness (Comparative Examples 3 to 5).

[0416] [Industrial Applicability]

[0417] According to the present invention, it is possible to provide an amino group-modified colloidal silica and a method for manufacturing the same, which suppresses the generation of aggregated particles to exhibit long-term stable dispersibility and can form a high-speed polished surface with high flatness even when used for polishing semiconductor wafers.

Claims

Claim 1 Amino group modified colloidal silica characterized by containing amino group modified silica particles having a pH of 8.50 to 9.50, a Si concentration in the solvent of 150 mass ppm or less, and a content of coarse particles with a particle size of 0.2 μm or more of 10,000,000 particles / mL or less when the silica particle concentration is 1 mass%. Claim 2 The amino group modified colloidal silica of claim 1, wherein the average secondary particle size of the amino group modified silica particles is 10 to 150 nm. Claim 3 A method for manufacturing amino group-modified colloidal silica as described in claim 1, characterized by sequentially performing, with respect to a contact solution obtained by contacting colloidal silica with an aminosilane coupling agent dispersion, (i) a first pH control process for adjusting the pH to 8.00 or lower while maintaining the zeta potential at -20.0 mV or lower, and (ii) a second pH control process for adjusting the pH to 8.50 to 9.50 by adding a base to the adjustment solution obtained in the first pH control process.

Images