Abstract: An object of the present invention is to provide a polishing composition and a polishing method, with which SiN can be selectively polished at a high polishing removal rate as compared with SiO2. The polishing composition contains colloidal silica in which an organic acid is fixed on a surface and a pH adjusting agent, in which an average aspect ratio of the colloidal silica in which the organic acid is fixed on the surface is 1.38 or more.

Abstract: A silica sol which does not gelate, has a high purity, and contains a high concentration of silica particles is provided. A silica sol containing silica particles and water, wherein a product of an average primary particle size of the silica particles and an average circularity of the silica particles is 15.0 or more and 31.2 or less, a concentration of the silica particles is 20 mass % or more, a total organic carbon amount per silica particle is less than 10 mass ppm, when the concentration of the silica particles is 20 mass %, a viscosity at 25° C. is 300 mPa·s or less, and a concentration of a metal impurity is less than 1 mass ppm.

Abstract: Provided is a method for producing a porous metal oxide. The method includes: preparing a slurry by mixing a metal source, a pore forming agent and an aqueous solvent; drying the slurry to obtain a metal oxide precursor; and sintering the metal oxide precursor to generate a porous metal oxide. The metal source is an organometallic compound or hydrolyzate thereof containing a metal that makes up the porous metal oxide; the pore forming agent is an inorganic compound that generates a gas by decomposing at a temperature equal to or lower than a temperature at which the metal oxide precursor is sintered; and the slurry is prepared using 50 parts by weight or more of the pore forming agent with respect to 100 parts by weight of the metal source.

Abstract: Provided is an absorption method of an element belonging to periods 4 to 6 and groups 3 to 15 of the periodic table. The method includes: preparing mesoporous alumina that satisfies at least one of the following items: (1) a surface hydroxyl content is 3.5 mmol/g or more; (2) a low-temperature CO2 desorption amount in CO2 thermal desorption amount spectrometry is 5 µmol/g or more; and (3) a low-temperature NH3 desorption amount in NH3 thermal desorption amount spectrometry is 25 µmol/g or more; and bringing a liquid containing an absorption target element in contact with the mesoporous alumina to absorb the absorption target element in the mesoporous alumina. The absorption target element is at least one type selected from the group consisting of an element belonging to periods 4 to 6 and groups 3 to 15 of the periodic table.

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 ?mol/g or more and 13.0 ?mol/g or less.

Abstract: The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol.

Abstract: Provided is a method for producing a porous metal oxide. The method includes: preparing a slurry by mixing a metal source, a pore forming agent and an aqueous solvent; drying the slurry to obtain a metal oxide precursor; and sintering the metal oxide precursor to generate a porous metal oxide. The metal source is an organometallic compound or hydrolyzate thereof containing a metal that makes up the porous metal oxide; the pore forming agent is an inorganic compound that generates a gas by decomposing at a temperature equal to or lower than a temperature at which the metal oxide precursor is sintered; and the slurry is prepared using 50 parts by weight or more of the pore forming agent with respect to 100 parts by weight of the metal source.

Abstract: The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol.

Abstract: The surface-modified colloidal silica according to an aspect of the present invention contains colloidal silica, and a surface-modifying group for modifying a surface of the colloidal silica, which has a polyoxyalkylene chain having a weight average molecular weight of 20,000 or more.

Abstract: Provided is a method for producing a porous metal oxide. The method includes: preparing a slurry by mixing a metal source, a pore forming agent and an aqueous solvent; drying the slurry to obtain a metal oxide precursor; and sintering the metal oxide precursor to generate a porous metal oxide. The metal source is an organometallic compound or hydrolyzate thereof containing a metal that makes up the porous metal oxide; the pore forming agent is an inorganic compound that generates a gas by decomposing at a temperature equal to or lower than a temperature at which the metal oxide precursor is sintered; and the slurry is prepared using 50 parts by weight or more of the pore forming agent with respect to 100 parts by weight of the metal source.

Abstract: To provide modified colloidal silica capable of improving the stability of the polishing speed with time when used as abrasive grains in a polishing composition for polishing a polishing object that contains a material to which charged modified colloidal silica easily adheres, such as a SiN wafer, and to provide a method for producing the modified colloidal silica. Modified colloidal silica, being obtained by modifying raw colloidal silica, wherein the raw colloidal silica has a number distribution ratio of 10% or less of microparticles having a particle size of 40% or less relative to a volume average particle size based on Heywood diameter (equivalent circle diameter) as determined by image analysis using a scanning electron microscope.

Abstract: The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol.

Abstract: To provide modified colloidal silica capable of improving the stability of the polishing speed with time when used as abrasive grains in a polishing composition for polishing a polishing object that contains a material to which charged modified colloidal silica easily adheres, such as a SiN wafer, and to provide a method for producing the modified colloidal silica. Modified colloidal silica, being obtained by modifying raw colloidal silica, wherein the raw colloidal silica has a number distribution ratio of 10% or less of microparticles having a particle size of 40% or less relative to a volume average particle size based on Heywood diameter (equivalent circle diameter) as determined by image analysis using a scanning electron microscope.

Abstract: Provided is a method for producing a porous metal oxide. The method includes: preparing a slurry by mixing a metal source, a pore forming agent and an aqueous solvent; drying the slurry to obtain a metal oxide precursor; and sintering the metal oxide precursor to generate a porous metal oxide. The metal source is an organometallic compound or hydrolyzate thereof containing a metal that makes up the porous metal oxide; the pore forming agent is an inorganic compound that generates a gas by decomposing at a temperature equal to or lower than a temperature at which the metal oxide precursor is sintered; and the slurry is prepared using 50 parts by weight or more of the pore forming agent with respect to 100 parts by weight of the metal source.

Abstract: There is provided a method for producing a silica sol including: a first step of adding an organic acid to at least one of liquid (A) containing an alkaline catalyst, water, and a first organic solvent and liquid (C) containing water; and a second step of mixing the liquid (A) with liquid (B) containing an alkoxysilane or its condensate and a second organic solvent, and the liquid (C) to make a reaction liquid after the first step.

Abstract: According to the present invention, there is provided a means for producing an aluminum hydroxide-coated SiC particle powder having a coating layer containing aluminum hydroxide on a surface of SiC particles. The present invention relates to a method for producing an aluminum hydroxide-coated SiC particle powder, which includes a coating step of maintaining a pH of a dispersion containing SiC particles, sodium aluminate, and water in a range of from 9 to 12 and forming coated particles having a coating layer containing aluminum hydroxide on a surface of the SiC particles.

Abstract: The present invention provides a means capable of suppressing the formation of fine particles in a method for producing a silica sol.

Abstract: According to the present invention, there is provided a means for producing an aluminum hydroxide-coated SiC particle powder having a coating layer containing aluminum hydroxide on a surface of SiC particles. The present invention relates to a method for producing an aluminum hydroxide-coated SiC particle powder, which includes a coating step of maintaining a pH of a dispersion containing SiC particles, sodium aluminate, and water in a range of from 9 to 12 and forming coated particles having a coating layer containing aluminum hydroxide on a surface of the SiC particles.

Abstract: Disclosed herein is a polishing composition comprising a pH of 6 or less, sulfonic acid-modified colloidal silica obtained by immobilizing sulfonic acid on surfaces of silica particles, and water, wherein the sulfonic acid-modified colloidal silica is derived from sulfonic acid-modified aqueous anionic silica sol produced by a production method comprising: a first reaction step of obtaining a reactant by heating raw colloidal silica having a number distribution ratio of 10% or less of microparticles having a particle diameter of 40% or less relative to a volume average particle diameter based on Heywood diameter (equivalent circle diameter) as determined by image analysis using a scanning electron microscope in the presence of a silane coupling agent having a functional group chemically convertible to a sulfonic acid group; and a second reaction step of converting the functional group to a sulfonic acid group by treating the reactant.

Abstract: To provide modified colloidal silica capable of improving the stability of the polishing speed with time when used as abrasive grains in a polishing composition for polishing a polishing object that contains a material to which charged modified colloidal silica easily adheres, such as a SiN wafer, and to provide a method for producing the modified colloidal silica. Modified colloidal silica, being obtained by modifying raw colloidal silica, wherein the raw colloidal silica has a number distribution ratio of 10% or less of microparticles having a particle size of 40% or less relative to a volume average particle size based on Heywood diameter (equivalent circle diameter) as determined by image analysis using a scanning electron microscope.