SULFONIC ACID-MODIFIED COLLOIDAL SILICA

Abstract

The present invention provides a means capable of further improving stability and washability under acidic conditions. The present invention is sulfonic acid-modified colloidal silica having an amount of sulfonic acid groups per 1 g of particles of 1.5 μmol/g or more and 13.0 μmol/g or less.

Claims

1. Sulfonic acid-modified colloidal silica, wherein an amount of sulfonic acid groups per 1 g of particles is 1.5 μmol/g or more and 13.0 μmol/g or less.

2. Sulfonic acid-modified colloidal silica according to claim 1, wherein the amount of sulfonic acid groups is 3.0 μmol/g or more and 10.5 μmol/g or less.

3. A production method of sulfonic acid-modified colloidal silica, comprising an organic solvent removal step of removing an organic solvent coexisting with colloidal silica under the condition of a pH of 7 or greater to obtain raw colloidal silica so that a residual organic solvent concentration in colloidal silica having a concentration of the organic solvent being 1% by mass or more becomes less than 1% by mass; and a modification step of modifying the raw colloidal silica with sulfonic acid to obtain sulfonic acid-modified colloidal silica, wherein the modification step comprises a first reaction step of heating the raw colloidal silica in the presence of a silane coupling agent having a functional group capable of chemically converting to a sulfonic acid group to obtain a reaction product, and a second reaction step of treating the reaction product to convert the functional group to a sulfonic acid group, and wherein in the first reaction step, an addition amount of the silane coupling agent is 0.1% by mass or more and less than 1.25% by mass relative to 100% by mass of silica particles contained in the raw colloidal silica.

4. The production method according to claim 3, wherein an addition amount of the silane coupling agent is 0.25% by mass or more and 1.0% by mass or less.

5. A polishing composition containing the sulfonic acid-modified colloidal silica according to claim 1.

Description

EXAMPLES

[0074] The present invention will be described in more detail by way of the following Examples and Comparative Examples. However, the technical scope of the present invention is not limited only to the following Examples. Unless otherwise specified, “%” and “part” refer to “% by mass” and “part by mass,” respectively. In the following Examples, the operations were carried out under the conditions of room temperature (20 to 25° C.)/relative humidity of 40 to 50% RH unless otherwise specified.

Example 1

<Synthesis of Silica Sol>

[0075] In a flask, 4842 g of methanol (manufactured by Kanto Chemical Co., Inc.), 750 g of water, and 178 g of a 29% by mass ammonia aqueous solution (manufactured by Kanto Chemical Co., Inc.) were mixed, and the mixture was maintained at 20° C., and thereto was added dropwise a mixed solution of 135 g of methanol (manufactured by Kanto Chemical Co., Inc.) and 508 g of tetramethoxysilane (TAMA CHEMICALS CO., LTD.) in 36 minutes of drop time. Thereafter, heat concentration and water replacement were carried out to obtain 1000 g of a silica sol having a concentration of silica particles of 19.5% by mass. The methanol concentration in this silica sol was measured by the following method using gas chromatography and was found to be less than 1% by mass (the detection limit or lower):

<<Measurement of Methanol Concentration Using Gas Chromatography>>

[0076] Apparatus: Gas chromatography GC-14B [0077] Measurement: Using a 10 μL syringe, 4 μL of a sample was extracted and injected into the above apparatus. The methanol concentration was calculated from the amounts of water and methanol obtained from the measurement.

<Synthesis of Sulfonic Acid-Modified Colloidal Silica>

[0078] To 1000 g of the silica sol obtained above was added dropwise 0.25 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 4.75 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0079] Next, the reaction solution was once cooled to 25° C., and 0.44 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then charged and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica (anion-modified colloidal silica).

Example 2

[0080] To 1000 g of the silica sol synthesized by the same method as in <Synthesis of silica sol> of Example 1 was added dropwise 0.50 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 9.50 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0081] Next, the reaction solution was once cooled to 25° C., and 0.88 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then charged and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

Example 3

[0082] To 1000 g of the silica sol synthesized by the same method as in <Synthesis of silica sol> of Example 1 was added dropwise 0.80 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 15.2 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0083] Next, the reaction solution was once cooled to 25° C., and 1.40 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then charged and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

Example 4

[0084] To 1000 g of the silica sol synthesized by the same method as in <Synthesis of silica sol> of Example 1 was added dropwise 1.00 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 19.0 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0085] Next, the reaction solution was once cooled to 25° C., and 1.75 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then charged and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

Example 5

[0086] To 1000 g of the silica sol synthesized by the same method as in <Synthesis of silica sol> of Example 1 was added dropwise 1.5 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 28.5 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0087] Next, the reaction solution was once cooled to 25° C., and 2.63 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then charged and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

Example 6

[0088] To 1000 g of the silica sol synthesized by the same method as in <Synthesis of silica sol> of Example 1 was added dropwise 2.0 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 38.0 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0089] Next, the reaction solution was once cooled to 25° C., and 3.50 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then charged and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

Comparative Example 1

[0090] In a flask, 4080 g of methanol (manufactured by Kanto Chemical Co., Inc.), 610 g of water, and 168 g of a 29% by mass ammonia solution (manufactured by Kanto Chemical Co., Inc.) were mixed, and the mixture was maintained at 20° C., and thereto was added dropwise a mixture of 135 g of methanol and 508 g of tetramethoxysilane (TMOS) (TAMA CHEMICALS CO., LTD.) in 25 minutes of drop time. Thereafter, the mixture underwent heat concentration and water replacement under the condition of a pH of 7 or greater to obtain 1000 g of silica sol having a concentration of silica particles of 19.5% by mass. The methanol concentration in this silica sol was measured by the above method using gas chromatography and was found to be less than 1% by mass (the detection limit or lower):

[0091] To 1000 g of the silica sol obtained was added dropwise 2.5 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 22.5 g of methanol, at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0092] Next, the reaction solution was once cooled to 25° C., and 4.3 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then fed and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

Comparative Example 2

[0093] To 1000 g of the silica sol synthesized by the same method as in <Synthesis of silica sol> of Example 1 was added dropwise 0.1 g of 3-mercaptopropyltrimethoxysilane (product name: KBM-803, manufactured by Shin-Etsu Chemical Co., Ltd.) that was separately mixed with 1.9 g of methanol (manufactured by Kanto Chemical Co., Inc.), at a flow rate of 1 mL/min, and the mixture was heated and replaced with water for 3 hours after boiling.

[0094] Next, the reaction solution was once cooled to 25° C., and 0.175 g of 30% by mass hydrogen peroxide water (manufactured by FUJIFILM Wako Pure Chemical Corporation) was then fed and the mixture was boiled again. After boiling, the mixture was replaced with water for 2 hours, and then cooled to room temperature (25° C.) to obtain sulfonic acid-modified colloidal silica.

<Measurement of Amount of Sulfonic Acid Groups>

[0095] Taking into consideration that in silica particles with sulfonic acid groups immobilized on a surface thereof, 1 mol of monovalent organic acid (sulfonic acid) reacts with 1 mol of monovalent potassium ion (K.sup.+), the amount of the sulfonic acid groups on the surface can be calculated from the following formula. The amount of sulfonic acid groups (unit: μmol/g) per 1 g of silica particles (as solid content) was calculated based on the following formula:

nS=K/Aw

[0096] In the above formula, [0097] nS represents the amount of sulfonic acid groups per 1 g of silica particles after surface treatment (as solid content) [unit: μmol/g]; [0098] K represents an analytical value of potassium in the solid [unit: ppm by mass]; and [0099] Aw represents the atomic weight of potassium [unit: g/mol]:

[0100] Specifically, first, to 21.0 g of a silica solution with a silica concentration of 19.5% by mass was added 21.0 g of a mixed solution of 0.01 mol/L hydrochloric acid and 0.01 mol/L potassium chloride, the mixture was mixed well, and then the resulting mixed solution underwent centrifugation in accordance with the following procedure: [0101] Procedure: the aforementioned mixture (silica sol) was added in a dedicated tube made of resin, and underwent centrifugation at 26,000 rpm (26,000 min-1) for 2 hours, and the precipitate obtained was washed with ultrapure water or ion exchanged water or the like. Thereafter, the precipitate was then evaporated to dryness and used as a sample. A high-performance high-speed refrigerated centrifuge Avanti (R) HP-30I manufactured by Beckman Coulter, Inc., was used as the centrifuge apparatus above.

[0102] The amount of potassium (K in the formula above) in the sample obtained was then measured using an inductively coupled plasma (ICP) atomic emission spectrometer, in accordance with the following procedure: [0103] Procedure: To 4 g of the sample obtained by centrifugation above was added 6 mL of nitric acid and 15 mL of hydrofluoric acid, and the mixture was evaporated to dryness. After the dryness, 0.5 mL of nitric acid and approximately 20 mL of ultrapure water were added, and the mixture was heated until vapor was generated. The resulting mixture was entirely collected, and increased to 50 g with ultrapure water, and further 3.0 g by weight of the liquid was taken therefrom, and the liquid was increased to 30 g by addition of ultrapure water, and then measurement of the resultant was carried out using an ICP emission spectrometer (model number: ICPS-8100 manufactured by Shimadzu Corporation).

[Evaluation]

(Washability Evaluation)

[0104] The sulfonic acid-modified colloidal silica obtained in the above Examples and Comparative Examples was observed for adhesiveness to a silicon nitride (SiN) wafer. [0105] Apparatus: A scanning electron microscope SU8000 (manufactured by Hitachi High-Tech Corporation) [0106] SiN wafer: A SiN wafer manufactured by Advantech Co., Ltd. [0107] Procedure: The obtained sulfonic acid-modified colloidal silica was diluted to a silica concentration of 14% by mass using pure water to prepare dispersion having a pH of 3 with a pH adjusting agent. A SiN wafer was immersed in this dispersion for 30 seconds and then rocked in pure water for 10 seconds. Thereafter the wafer was completely dried with N.sub.2 gas, and then was observed in ten fields of view by using a scanning electron microscope SU8000 at a magnification of 50,000×. [0108] Evaluation: The SiN wafer was observed by SEM after drying, and the proportion of the area with particles attached was evaluated using the following evaluation criteria when the total area of the 10 fields of view in total at a magnification of 50,000× was regarded as 100%. [0109] A: 10% or less (extremely favorable washability) [0110] B: More than 10% or 30% or less (favorable washability) [0111] C: More than 30% and 50% or less (no major problems in washability) [0112] D: More than 50% (poor washability)

(Stability Test)

[0113] Each 100 g of the sulfonic acid-modified colloidal silica prepared in the above Examples and Comparative Examples was separated and adjusted to a pH of 2 and a pH of 3, respectively, using a 0.1 mol/L HCl solution and a 0.1 mol/L NaOH solution as pH adjusting agents. They were sealed and stored in an air bath at 80° C. for 24 hours.

[0114] After 24 hours, each sample was taken out from the air bath and confirmed to reach solution temperature of room temperature (25° C.), and then presence or absence of precipitation or gelation was visually observed.

[0115] Each sample was evaluated and determined as (A) favorable when no change from before storage at 80° C. was observed, (B) slightly poor when slight precipitation was observed, and (C) poor when drastic precipitation was observed or the sample gelled.

[0116] Table 1 below shows the amounts of sulfonic acid groups in the sulfonic acid-modified colloidal silica and evaluation results for Examples and Comparative Examples.

TABLE-US-00001 TABLE 1 Addition amount of silane coupling agent in production Amount of Wash- (% by mass relative sulfonic acid ability to silica particles groups evalu- Stability solid content) (μmol/g) ation pH2 pH3 Example 1 0.125 2.0 A A A Example 2 0.25 3.2 A A A Example 3 0.4 5.9 A A A Example 4 0.5 6.1 B A A Example 5 0.75 8.1 B A A Example 6 1.0 10.2 B A A Comparative 1.25 13.2 D A A Example 1 Comparative 0.05 1.3 A C C Example 2

[0117] As shown in Table 1 above, the sulfonic acid-modified colloidal silica of Examples 1 to 6 according to the present invention was found to have excellent stability and washability under acidic conditions. The sulfonic acid-modified colloidal silica of Comparative Example 1, on the other hand, in which the amount of sulfonic acid groups exceeded 13.0 μmol/g, was found to have poor washability. The sulfonic acid-modified colloidal silica of Comparative Example 2, in which the amount of sulfonic acid groups was less than 1.5 μmol/g, was found to have poor stability under acidic conditions.

[0118] This application is based on Japanese Patent Application No. 2022-053011 filed on Mar. 29, 2022, the content of which is hereby incorporated by reference in its entirety.