Polishing slurry composition

Abstract

To provide a polishing liquid composition enabling an improvement of a polishing speed and a suppression of a deterioration of the polishing speed in a use of a continuous of a polishing pad to be made compatible with each other, even if content of a silica particle is small.SOLUTION: The present disclosure, as an aspect, relates to a polishing liquid composition containing the following component A and the following component B, wherein a content of the component A is 0.1 mass% or less, a mass ratio of B / A of the content of a component B to the content of the component A is 0.07 or larger, and pH exceeds 8.5 and is 14 or less. The component A is a silica particle, the component B is water-soluble polymer containing basic nitrogen atom, wherein at least a part of the basic nitrogen atom includes a hetero atom (excluding a basic property nitrogen atom) at a position selected from a β position, a γ position, and a δ position.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a polishing composition for use in polishing silicon substrates, a polishing method using the same, and a method for manufacturing semiconductor substrates. [Background technology]

[0002] Polishing compositions containing silica particles are known as polishing compositions used for polishing silicon substrates used in the manufacture of semiconductor substrates. In recent years, with the increasing demand for semiconductors, there has been a demand for polishing compositions that can be diluted at a high ratio to achieve high productivity (high surface quality and high polishing rate) while reducing the costs of using and disposing of the polishing composition. In response to this demand, polishing compositions that achieve good surface quality (low haze surface) in the process of diluting the polishing composition stock solution by 50 times or more by volume, and polishing compositions containing cationic water-soluble polymers for the purpose of improving the polishing rate have been proposed (e.g., Patent Documents 1 and 2).

[0003] Patent Document 1 proposes a manufacturing method including a step of diluting a stock solution of a polishing composition containing abrasive grains, a basic compound, a water-soluble polymer, and water so that the pH change is 0.15 or more. The example of this document describes a polishing composition containing 0.06% colloidal silica, ammonia, and hydroxyethyl cellulose (HEC) with a weight-average molecular weight of 250,000. Patent Document 2 proposes a semiconductor polishing composition containing abrasive grains, a basic compound, and two or more water-soluble polymers, the water-soluble polymers including a cationic water-soluble polymer containing a nitrogen-containing group. The examples in this document describe a semiconductor polishing composition containing 0.45% colloidal silica, ammonia, tetramethylammonium hydroxide, HEC with a weight-average molecular weight of 800,000, and polyethyleneimine (PEI). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-53114 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-352042 Summary of the Invention [Problem to be solved by the invention]

[0005] The polishing liquid described in Patent Document 1, which is obtained by diluting the polishing composition stock solution at a high ratio and using it with a silica concentration of 0.1 mass % or less, is insufficient because it significantly reduces the removal rate. The polishing liquid described in Patent Document 2, which contains a cationic water-soluble polymer with a nitrogen-containing group such as PEI, improves the removal rate, but the removal rate tends to decrease with continued use of the polishing pad, resulting in unstable polishing quality, an increase in the number of times the polishing pad needs to be dressed, a shorter period until the polishing pad needs to be replaced, and reduced productivity.

[0006] The present disclosure provides a polishing composition that can improve the polishing rate while suppressing a decrease in the polishing rate during continued use of a polishing pad, even when the content of silica particles is small, and also provides a method for polishing a silicon substrate using the same, and a method for manufacturing a semiconductor substrate. [Means for solving the problem]

[0007] In one aspect, the present disclosure relates to a polishing liquid composition containing the following component A and component B, wherein the content of component A is 0.1 mass % or less, the mass ratio B / A of the content of component B to the content of component A is 0.07 or more, and the pH is more than 8.5 and 14 or less. Component A: Silica particles Component B: a water-soluble polymer containing basic nitrogen atoms, at least some of which contain heteroatoms (excluding the basic nitrogen atoms) at positions selected from the β-, γ-, and δ-positions

[0008] In one aspect, the present disclosure relates to a method for polishing a silicon substrate, comprising a step of polishing a silicon substrate to be polished using the polishing liquid composition of the present disclosure.

[0009] In one aspect, the present disclosure relates to a method for producing a semiconductor substrate, comprising the steps of polishing a silicon substrate to be polished with the polishing liquid composition of the present disclosure and cleaning the polished silicon substrate. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a polishing liquid composition that can improve the polishing rate while suppressing a decrease in the polishing rate during continued use of a polishing pad, even when the content of silica particles is small, a method for polishing a silicon substrate using the polishing liquid composition, and a method for manufacturing a semiconductor substrate. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure is based on the finding that by using a polishing liquid composition for silicon substrates that contains silica particles and a specific water-soluble polymer having a basic nitrogen atom and has a pH greater than 8.5 and not greater than 14, it is possible to achieve both an improvement in the polishing rate and suppression of a decrease in the polishing rate during continued use of a polishing pad, even with a small content of silica particles.

[0012] That is, in one aspect, the present disclosure relates to a polishing liquid composition (hereinafter also referred to as the "polishing liquid composition of the present disclosure") containing the following component A and component B, wherein the content of component A is 0.1 mass % or less, the mass ratio B / A of the content of component B to the content of component A is 0.07 or more, and the pH is more than 8.5 and 14 or less. Component A: Silica particles Component B: a water-soluble polymer containing basic nitrogen atoms, at least some of which contain heteroatoms (excluding the basic nitrogen atoms) at positions selected from the β-, γ-, and δ-positions

[0013] According to one or more embodiments of the present disclosure, even if the content of silica particles is small, it is possible to achieve both an improvement in the polishing rate and suppression of a decrease in the polishing rate during continued use of the polishing pad.

[0014] Although the details of the mechanism by which the effects of the present disclosure are exerted are not clear, it is presumed as follows. Generally, even if a polishing solution containing a cationic water-soluble polymer with a nitrogen-containing group, such as polyethyleneimine, maintains a certain removal rate, the removal rate tends to decrease with continued use of the polishing pad. One of the reasons for this is thought to be clogging of the polishing pad. Typical cationic water-soluble polymers adhere not only to silicon substrates and silica particles, but also to the surface of the polishing pad. To prevent clogging, a sufficient amount of cationic water-soluble polymer must be added to the polishing pad, adsorbing it to form a protective film, suppressing excessive adhesion of silica particles to the polishing pad through steric and charge repulsion. However, typical cationic water-soluble polymers have a strong adsorption force to silica particles, which tends to cause aggregation and reduce product stability. Therefore, it is difficult to add a sufficient amount of cationic water-soluble polymer to adhere to the polishing pad. In this disclosure, a specific water-soluble polymer (component B) containing a basic nitrogen atom is adsorbed to silica particles (component A) without causing aggregation of the silica particles, allowing the content of component B to be increased relative to the content of component A. This is thought to be because component B has a heteroatom near the basic nitrogen atom, which alleviates the strong interaction between the nitrogen atom and the silica particles. As a result, some of the component B that is not adsorbed to the silica particles is adsorbed to the polishing pad and forms a protective film, which prevents the silica particles from adhering to the polishing pad. This allows the silica particles to be appropriately discharged from the polishing pad, thereby preventing a decrease in the removal rate during continued use of the polishing pad. Furthermore, under alkaline polishing conditions where the pH is greater than 8.5 and less than 14, both the silica abrasive grains and the silicon substrate being polished have negative charges, and electrostatic repulsion is constantly occurring. Reducing this electrostatic repulsion is thought to be effective in improving the polishing rate. In the present disclosure, a specific water-soluble polymer (component B) is adsorbed to silica particles (component A) and the silicon substrate to be polished by the van der Waals forces of the entire molecule, significantly reducing the electrostatic repulsion between the silica particles (component A) and the silicon substrate to be polished, thereby efficiently attracting a small amount of silica particles to the silicon substrate to be polished. Therefore, it is believed that the polishing rate can be improved even when the content of component A is 0.1 mass % or less. However, the present disclosure need not be construed as being limited to these mechanisms.

[0015] [Silicon substrate to be polished] In one or more embodiments, the polishing liquid composition of the present disclosure is a polishing composition for silicon substrates, and can be used, for example, in a polishing step of polishing a silicon substrate to be polished in a method for producing a semiconductor substrate, or in a polishing step of polishing a silicon substrate to be polished in a method for polishing a silicon substrate. In one or more embodiments, examples of the silicon substrate to be polished using the polishing liquid composition of the present disclosure include silicon wafers and silicon substrates, and in one or more embodiments, examples of the silicon substrate to be polished include single crystal silicon substrates, polysilicon substrates, substrates having a polysilicon film, SiN substrates, etc. From the viewpoint of exerting the effects of the polishing liquid composition of the present disclosure, the silicon substrate to be polished is preferably a single crystal silicon substrate or a polysilicon substrate, and more preferably a single crystal silicon substrate.

[0016] [Silica particles (component A)] The polishing composition of the present disclosure contains silica particles (hereinafter also referred to as "Component A") as an abrasive. Examples of Component A include colloidal silica, fumed silica, pulverized silica, and surface-modified silica thereof. Colloidal silica is preferred from the viewpoint of achieving both improved polishing rate and storage stability, and from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects, and scratches. Component A may be one type or a combination of two or more types.

[0017] From the viewpoint of ease of use, the use form of Component A is preferably a slurry. When Component A contained in the polishing liquid composition of the present disclosure is colloidal silica, from the viewpoint of preventing contamination of silicon substrates with alkali metals, alkaline earth metals, etc., the colloidal silica is preferably obtained from a hydrolyzate of an alkoxysilane. Silica particles obtained from a hydrolyzate of an alkoxysilane can be produced by a conventionally known method.

[0018] From the viewpoint of maintaining the polishing rate, the average primary particle diameter of component A is preferably 10 nm or more, more preferably 15 nm or more, and even more preferably 20 nm or more, and from the viewpoint of improving storage stability and improving surface quality such as reducing surface roughness (haze), surface defects, and scratches, the average primary particle diameter of component A is preferably 50 nm or less, more preferably 45 nm or less, even more preferably 40 nm or less, and even more preferably 30 nm or less. From the same viewpoint, the average primary particle diameter of component A is preferably 10 nm or more and 50 nm or less, more preferably 15 nm or more and 45 nm or less, even more preferably 20 nm or more and 40 nm or less, and preferably 20 nm or more and 30 nm or less. In the present disclosure, the average primary particle diameter of component A is determined by the specific surface area S (m 2 The average primary particle size is calculated using the formula (1 / g). The average primary particle size is a value measured by the method described in the examples.

[0019] From the viewpoint of maintaining the polishing rate, the average secondary particle diameter of component A is preferably 20 nm or more, more preferably 30 nm or more, and even more preferably 40 nm or more, and from the viewpoint of improving storage stability and improving surface quality such as reducing surface roughness (haze), surface defects, and scratches, it is preferably 100 nm or less, more preferably 90 nm or less, even more preferably 80 nm or less, even more preferably 70 nm or less, and even more preferably 60 nm or less. From the same viewpoint, the average secondary particle diameter of component A is preferably 20 nm or more and 100 nm or less, more preferably 30 nm or more and 90 nm or less, even more preferably 30 nm or more and 80 nm or less, even more preferably 30 nm or more and 70 nm or less, and even more preferably 40 nm or more and 60 nm or less. In the present disclosure, the average secondary particle size is a value measured by dynamic light scattering (DLS) method, and is a value measured by the method described in the Examples.

[0020] The degree of association of component A is preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less, from the viewpoint of improving storage stability and surface quality, and is preferably 1.1 or more, more preferably 1.5 or more, and even more preferably 1.8 or more, from the viewpoint of achieving both an improvement in the removal rate and storage stability and improving surface quality. In the present disclosure, the degree of association of component A is a coefficient representing the shape of silica particles and is calculated by the following formula. Degree of association = average secondary particle size / average primary particle size

[0021] The degree of association of component A can be adjusted by using methods described in, for example, JP-A Nos. 6-254383, 11-214338, 11-60232, 2005-060217, and 2005-060219.

[0022] The shape of component A is preferably a so-called spherical shape and / or a so-called cocoon shape from the viewpoint of achieving both an improvement in removal rate and storage stability, and from the viewpoint of improving surface quality.

[0023] The content of component A in the polishing composition of the present disclosure is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, and even more preferably 0.03 mass% or more, calculated as SiO2, from the viewpoint of improving the removal rate. From the viewpoints of reducing the environmental impact, reducing wastewater treatment costs, improving storage stability, and improving surface quality, the content of component A is preferably 0.1 mass% or less, more preferably less than 0.1 mass%, more preferably 0.09 mass% or less, even more preferably 0.08 mass% or less, and even more preferably 0.07 mass% or less. From the same viewpoint, the content of component A in the polishing composition of the present disclosure is preferably 0.01 mass% or more and 0.1 mass% or less, more preferably 0.02 mass% or more and 0.09 mass% or less, more preferably 0.02 mass% or more and 0.08 mass% or less, and even more preferably 0.03 mass% or more and 0.07 mass% or less. When component A is a combination of two or more types, the content of component A refers to the total content thereof.

[0024] [Water-soluble polymer containing a basic nitrogen atom (component B)] The polishing liquid composition of the present disclosure contains a water-soluble polymer (hereinafter also referred to as "Component B") containing basic nitrogen atoms, at least some of which contain heteroatoms (excluding basic nitrogen atoms) at positions selected from the β, γ, and δ positions. Component B is believed to adjust the zeta potential of silica particles (Component A) and the silicon substrate to be polished, thereby reducing the electrostatic repulsion between the silica particles (Component A) and the silicon substrate to be polished and suppressing aggregation of the silica particles. In the present disclosure, "water-soluble" refers to a solubility of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more, in water (20°C). Examples of heteroatoms include oxygen atoms, sulfur atoms, nitrogen atoms (excluding basic nitrogen atoms), and halogens (e.g., fluorine, chlorine, etc.). In one or more embodiments, the heteroatom is an oxygen atom derived from glycidol modification. In the present disclosure, the term "basic nitrogen atom" refers to a nitrogen atom contained in a basic nitrogen-containing functional group. Examples of basic nitrogen-containing functional groups include primary amino groups, secondary amino groups, tertiary amino groups, quaternary ammonium groups, and nitrogen-containing aromatic ring groups (e.g., pyridyl groups and imidazolyl groups).

[0025] From the viewpoint of achieving both an improvement in the removal rate and storage stability, Component B preferably contains a structural unit derived from one or more monomers selected from allylamine and diallylamine, and more preferably contains a structural unit derived from allylamine. In one or more embodiments, from the viewpoint of availability, Component B is preferably an amino group-containing water-soluble polymer containing an allylamine-derived structural unit (hereinafter also referred to as "Component B1"), and in one or more embodiments, it is preferably an amino group-containing water-soluble polymer containing a diallylamine-derived structural unit (hereinafter also referred to as "Component B2").

[0026] (Component B1: Amino group-containing water-soluble polymer containing allylamine-derived structural units) In one or more embodiments, at least a portion of the amino groups in the allylamine-derived structural unit preferably have a sterically shielding group from the viewpoints of achieving both improved polishing rate and storage stability, as well as from the viewpoint of availability. In the present disclosure, the sterically shielding group refers to a sterically (bulky) substituent that can shield the nitrogen atom of the amino group of Component B1 to suppress cationization. From the same viewpoint, the amino group having the sterically shielding group is preferably a secondary or tertiary amino group containing a hydrocarbon group having 2 to 11 carbon atoms and a heteroatom. Examples of the heteroatom include an oxygen atom, a sulfur atom, a nitrogen atom (excluding basic nitrogen atoms), and a halogen atom (e.g., fluorine, chlorine, etc.), among which an oxygen atom is preferred. In one or more embodiments, the heteroatom is preferably an oxygen atom derived from glycidol modification. The number of carbon atoms in the hydrocarbon group is preferably 2 or more, more preferably 3 or more, from the viewpoint of improving the shielding ability of the amino group (suppressing cationization of the nitrogen atom of the amino group) and from the viewpoint of achieving both an improvement in the polishing rate and storage stability. From the viewpoint of improving water solubility and availability, the number of carbon atoms in the hydrocarbon group is preferably 11 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 4 or less.

[0027] In one or more embodiments, the amino group having a sterically shielding group is a modified group of an amino group by a glycidol derivative, and in one or more embodiments, it is a group formed by reacting an amino group in an allylamine-derived structural unit with a glycidol derivative. At least a portion of the amino groups in component B1 are modified with the glycidol derivative to form an amino group having a sterically shielding group. From the viewpoints of improving storage stability and surface quality, the equivalent of the glycidol derivative relative to the number of amino groups (1 equivalent) in the allylamine-derived structural unit (hereinafter also referred to as the "glycidol modification rate") is preferably 0.3 or more, more preferably 0.5 or more, even more preferably 0.8 or more, even more preferably 1 or more, preferably more than 1.1, more preferably 1.2 or more, even more preferably 1.3 or more, even more preferably 1.4 or more. From the viewpoint of improving the polishing rate, it is preferably 4 or less, more preferably 3 or less, even more preferably 2.5 or less, even more preferably 2 or less, even more preferably 1.9 or less, even more preferably 1.8 or less.

[0028] In the present disclosure, the glycidol modification rate is 13 The glycidol modification rate is a value measured by the method described in the Examples using C-NMR. However, the glycidol modification rate can also be measured by the following method (1) or (2). (1) It can be calculated from the amino group equivalent of the allylamine polymer used as the reaction raw material and the number of moles of the glycidol derivative. (2) The nitrogen content N (mass %) of the reaction product of the glycidol derivative and the allylamine polymer is measured, and the nitrogen content N can be calculated from the following formula: Glycidol modification rate = A / B Here, A=(100−N×molecular weight of allylamine monomer / 14) / molecular weight of glycidol derivative, and B=N / 14.

[0029] Examples of the glycidol derivative include glycidol and alkyl glycidyl ether, and glycidol is preferred from the viewpoints of availability and achieving both improved polishing rate and storage stability. The alkyl group of the alkyl glycidyl ether is preferably an alkyl group having 1 to 8 carbon atoms from the viewpoint of availability, and examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, and a 2-ethylhexyl group. Examples of the alkyl glycidyl ether include methyl glycidyl ether and 2-ethylhexyl glycidyl ether.

[0030] In one or more embodiments, component B1 includes a polyallylamine in which at least some of the amino groups have a sterically shielding group, and in one or more embodiments, a reaction product of a polyallylamine with a glycidol derivative.

[0031] In one or more embodiments, Component B1 may be a compound containing a structural unit of the following formula (I) (glycidol-modified polyallylamine). [ka]

[0032] In formula (I), R 1 and R 2 are each a hydrogen atom or a sterically shielding group. Examples of the sterically shielding group include modifying groups derived from glycidol derivatives, and in one or more embodiments, examples thereof include one-molar adducts or two-molar adducts of glycidol, and in one or more embodiments, examples thereof include -CHCH(OH)CH(OH), -CHCH(OH)CHO-CHCH(OH)CH(OH), etc.

[0033] (Component B2: Amino group-containing water-soluble polymer containing constitutional units derived from diallylamine) In one or more embodiments, from the viewpoint of achieving both an improvement in the removal rate and storage stability, at least a portion of the amino groups in the diallylamine-derived structural unit preferably have an electron-withdrawing group at the β- or γ-position of the amino group. Examples of the electron-withdrawing group include a group represented by the following formula (II): [ka]

[0034] In one or more embodiments, component B2 includes a compound containing a constitutional unit derived from diallylamine and a constitutional unit derived from sulfur dioxide, and examples thereof include a compound containing a constitutional unit represented by the following formula (III): [ka]

[0035] In formula (III), R 3 is an alkyl group having 1 to 3 carbon atoms which may have a hydroxyl group. From the viewpoint of availability and economic efficiency, R 3 is preferably a methyl group. Furthermore, n+m=1, and n and m are 0 or 1. From the same viewpoint, a compound where m=1 and n=0 is preferred. Note that a mixture of a compound where m=1 and n=0 and a compound where m=0 and n=1 may also be used.

[0036] In one or more embodiments, Component B2 includes a compound containing a constituent unit represented by the following formula (IV), such as a methyldiallylamine / sulfur dioxide copolymer. [ka]

[0037] From the viewpoint of improving the polishing rate, the pKa of component B is preferably 5 or more, more preferably 5.5 or more, even more preferably 5.9 or more, and even more preferably 6.3 or more, and from the viewpoint of improving the surface quality, it is preferably 8.5 or less, more preferably 8.3 or less, even more preferably 8.1 or less, and even more preferably 8 or less.

[0038] From the viewpoint of improving the polishing rate, the weight-average molecular weight of Component B is preferably 800 or more, more preferably 1,000 or more, even more preferably 2,000 or more, even more preferably 3,000 or more, even more preferably 4,000 or more, even more preferably 5,000 or more, even more preferably 6,000 or more, even more preferably 7,000 or more, even more preferably 8,000 or more, even more preferably 9,000 or more, even more preferably 10,000 or more. From the viewpoint of achieving both an improvement in the polishing rate and storage stability and reducing surface roughness and surface defects, the weight-average molecular weight of Component B is preferably 100,000 or less, more preferably 90,000 or less, even more preferably 80,000 or less, even more preferably 70,000 or less, even more preferably 60,000 or less, even more preferably 50,000 or less, even more preferably 40,000 or less. The weight-average molecular weight of Component B in the present disclosure can be measured, for example, by the method described in the Examples.

[0039] From the viewpoint of achieving both an improved removal rate and storage stability, the content of Component B in the polishing composition of the present disclosure is preferably 10 ppm or more, more preferably 30 ppm or more, and even more preferably 50 ppm or more, and from the same viewpoint, is preferably 200 ppm or less, more preferably 150 ppm or less, and even more preferably 100 ppm or less. In the present disclosure, 1 mass % is 10,000 ppm (the same applies hereinafter).

[0040] The ratio of the content of component B to the content of component A in the polishing liquid composition of the present disclosure (mass ratio B / A) is 0.07 or more, preferably 0.09 or more, and more preferably 0.11 or more, from the viewpoint of suppressing a decrease in the polishing rate during continued use of the polishing pad and from the viewpoint of improving the polishing rate, and from the same viewpoint, is preferably 0.4 or less, more preferably 0.3 or less, and even more preferably 0.25 or less.

[0041] [water] In one or more embodiments, the polishing composition of the present disclosure may contain water. Examples of water include ion-exchanged water and ultrapure water. The content of water in the polishing composition of the present disclosure may be, for example, the remainder of Component A, Component B, and the optional components described below.

[0042] [Nonionic water-soluble polymer (ingredient C)] In one or more embodiments, the polishing liquid composition of the present disclosure may contain a nonionic water-soluble polymer (hereinafter also referred to as "component C") from the viewpoint of reducing surface roughness (haze). From the same viewpoint, component C is preferably a nonionic water-soluble polymer having an alkylene oxide group, a hydroxyl group, or an amide group in the molecule. Examples of the alkylene oxide group include an ethylene oxide group and a propylene oxide group. Component C may be one type or a combination of two or more types.

[0043] From the viewpoint of reducing surface roughness (haze), component C can be at least one selected from polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyhydroxyethylacrylamide, polyethylene glycol (PEG) or polypropylene glycol having a weight-average molecular weight of 1,000 or more and 20,000 or less. From the viewpoints of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze), and from the viewpoints of suppressing foaming of the polishing liquid, the alkyl group of the polyglycerol alkyl ether is preferably an alkyl group having 3 to 22 carbon atoms, more preferably an alkyl group having 5 to 16 carbon atoms, and even more preferably an alkyl group having 7 to 12 carbon atoms. The alkyl group may be a linear alkyl group or a branched alkyl group. From the viewpoint of improving wettability, the average degree of polymerization of the glycerol units of the polyglycerol alkyl ether is 5 or more, preferably 10 or more, more preferably 15 or more, and even more preferably 18 or more. From the viewpoint of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze), it is 100 or less, preferably 60 or less, more preferably 45 or less, and even more preferably 25 or less. Examples of the polyglycerol alkyl ether include polyglycerol lauryl ether, polyglycerol decyl ether, and polyglycerol myristyl ether. From the viewpoints of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze), and from the viewpoints of suppressing foaming of the polishing liquid, the alkyl group of the polyglycerol alkyl ester is preferably an alkyl group having 3 to 22 carbon atoms, more preferably an alkyl group having 5 to 16 carbon atoms, and even more preferably an alkyl group having 7 to 12 carbon atoms. The alkyl group may be a linear alkyl group or a branched alkyl group. From the viewpoint of improving wettability, the average degree of polymerization of the glycerol units of the polyglycerol alkyl ester is 5 or more, preferably 10 or more, more preferably 15 or more, and even more preferably 18 or more. From the viewpoint of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze), it is 100 or less, preferably 60 or less, more preferably 45 or less, and even more preferably 25 or less. Examples of the polyglycerol alkyl ester include polyglycerol lauryl ester, polyglycerol decyl ester, and polyglycerol myristyl ester. From the viewpoint of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze), the hydroxyalkyl cellulose is preferably at least one selected from hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, and hydroxybutyl cellulose, and more preferably HEC. Among these, from the viewpoint of reducing surface roughness (haze), Component C is preferably at least one selected from polyethylene glycol (PEG) or polypropylene glycol having a weight average molecular weight of 1,000 or more and 20,000 or less, and hydroxyethyl cellulose (HEC).

[0044] The weight-average molecular weight of component C is preferably 1,000 or more, more preferably 1,500 or more, and even more preferably 2,000 or more, from the viewpoint of preventing a decrease in the polishing rate during continued use of the polishing / polishing pad and from the viewpoint of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze).From the same viewpoint and from the viewpoint of the filterability of the polishing liquid, it is preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 300,000 or less. When component C is PEG or polypropylene glycol having a weight-average molecular weight of 1,000 or more and 20,000 or less, the weight-average molecular weight of component C is preferably 1,000 or more, more preferably 2,000 or more, even more preferably 3,000 or more, and even more preferably 4,000 or more, from the viewpoint of preventing a decrease in the removal rate during continued use of the polishing pad and from the viewpoint of achieving both an improvement in the removal rate and a reduction in surface roughness (haze); and from the same viewpoint and from the viewpoint of the filterability of the polishing liquid, it is preferably 20,000 or less, more preferably 10,000 or less, even more preferably 8,000 or less, and even more preferably 6,000 or less. When component C is HEC, from the same viewpoint, the weight average molecular weight of component C is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 150,000 or more, and is preferably 500,000 or less, more preferably 400,000 or less, and even more preferably 300,000 or less. The weight average molecular weight of Component C can be measured by the method described in the Examples below.

[0045] When the polishing liquid composition of the present disclosure contains component C, the content of component C in the polishing liquid composition of the present disclosure is preferably 1 ppm or more, more preferably 3 ppm or more, and even more preferably 5 ppm or more from the viewpoint of reducing surface roughness (haze), and is preferably 200 ppm or less, more preferably 150 ppm or less, and even more preferably 100 ppm or less from the viewpoint of improving the removal rate. From the same viewpoint, the content of component C in the polishing liquid composition of the present disclosure is preferably 1 ppm or more and 200 ppm or less, more preferably 3 ppm or more and 150 ppm or less, and even more preferably 5 ppm or more and 100 ppm or less. When component C is a combination of two or more types, the content of component C refers to the total content thereof.

[0046] When the polishing liquid composition of the present disclosure contains component C, the ratio C / A of the content of component C to the content of component A (mass ratio C / A) in the polishing liquid composition of the present disclosure is, from the viewpoint of suppressing a decrease in the removal rate during continued use of the polishing pad and from the viewpoint of achieving both an improvement in removal rate and a reduction in surface roughness (haze), preferably 0.001 or more, more preferably 0.005 or more, even more preferably 0.01 or more, even more preferably 0.015 or more, even more preferably 0.02 or more, even more preferably 0.025 or more, and preferably 1 or less, more preferably 0.7 or less, even more preferably 0.4 or less, more preferably 0.2 or less, and even more preferably 0.1 or less. From the same viewpoint, the mass ratio C / A in the polishing liquid composition of the present disclosure is preferably 0.005 or more and 0.2 or less, more preferably 0.01 or more and 0.1 or less, even more preferably 0.015 or more and 0.1 or less.

[0047] [Nitrogen-containing basic compound (component D)] In one or more embodiments, the polishing liquid composition of the present disclosure preferably further contains a nitrogen-containing basic compound (hereinafter also referred to as "component D") from the viewpoint of adjusting the pH. Component D is preferably a water-soluble nitrogen-containing basic compound from the viewpoint of achieving both improved removal rate and storage stability, and from the viewpoint of improving surface quality. In the present disclosure, "water-soluble" refers to having a solubility in water (20°C) of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more. In the present disclosure, "water-soluble nitrogen-containing basic" refers to a nitrogen-containing compound that exhibits basicity when dissolved in water. In one or more embodiments, component D does not include component B. Component D may be one type or a combination of two or more types.

[0048] In one or more embodiments, Component D may be at least one selected from an amine compound and an ammonium compound, such as ammonia, ammonium hydroxide, ammonium carbonate, ammonium hydrogencarbonate, dimethylamine, trimethylamine, diethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, N-methylethanolamine, N-methyl-N,N-diethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, N,N-dibutylethanolamine, N-(β-aminoethyl)ethanolamine, monoisopropanolamine, diisopropanolamine, triisopropanolamine, ethylenediamine, hexamethylenediamine, piperazine hexahydrate, anhydrous piperazine, 1-(2-aminoethyl)piperazine, N-methylpiperazine, diethylenetriamine, tetramethylammonium hydroxide, and hydroxyamine, or a combination of two or more selected from these. Among these, from the viewpoint of achieving both an improvement in removal rate and storage stability, ammonia or a mixture of ammonia and hydroxyamine is preferred as component D, and ammonia is more preferred.

[0049] When the polishing composition of the present disclosure contains component D, the content of component D in the polishing composition of the present disclosure is preferably 5 ppm or more, more preferably 10 ppm or more, and even more preferably 20 ppm or more from the viewpoints of improving storage stability and polishing rate; and from the viewpoints of improving storage stability, improving surface quality, and suppressing corrosion of the silicon substrate, it is preferably 500 ppm or less, more preferably 300 ppm or less, even more preferably 150 ppm or less, and even more preferably 100 ppm or less. From the same viewpoint, the content of component D in the polishing composition of the present disclosure is preferably 5 ppm or more and 500 ppm or less, more preferably 10 ppm or more and 300 ppm or less by mass, more preferably 20 ppm or more and 150 ppm or less, even more preferably 20 ppm or more and 100 ppm or less. When component D is a combination of two or more types, the content of component D refers to the total content thereof.

[0050] When the polishing liquid composition of the present disclosure contains component D, the ratio D / A of the content of component D to the content of component A in the polishing liquid composition of the present disclosure (mass ratio D / A) is preferably 0.002 or more, more preferably 0.01 or more, even more preferably 0.02 or more, and even more preferably 0.05 or more from the viewpoint of improving the removal rate, and is preferably 1 or less, more preferably 0.5 or less, even more preferably 0.3 or less, and even more preferably 0.2 or less from the viewpoint of improving storage stability, improving surface quality, and suppressing corrosion of the silicon substrate. From the same viewpoint, the mass ratio D / A in the polishing liquid composition of the present disclosure is preferably 0.002 or more and 1 or less, more preferably 0.01 or more and 0.5 or less, more preferably 0.02 or more and 0.3 or less, and even more preferably 0.05 or more and 0.2 or less.

[0051] [Other ingredients] The polishing liquid composition of the present disclosure may further contain other components to the extent that the effects of the present disclosure are not impaired. In one or more embodiments, the other components include water-soluble polymers other than Component B and Component C, pH adjusters other than Component D, preservatives, alcohols, chelating agents, and oxidizing agents.

[0052] [pH] From the viewpoint of achieving both improved removal rate and storage stability, the pH of the polishing composition of the present disclosure is greater than 8.5, preferably greater than 9, more preferably greater than 9.5, and even more preferably greater than 10. From the viewpoint of improving surface quality, the pH is less than 14, preferably less than 13, more preferably less than 12.5, even more preferably less than 12, even more preferably less than 11.5, and even more preferably less than 11. From the same viewpoint, the pH of the polishing composition of the present disclosure is greater than 8.5 and less than 14, preferably less than 9, more preferably less than 13, more preferably less than 9, more preferably less than 12.5, even more preferably less than 9, more preferably less than 12, even more preferably less than 9.5, even more preferably less than 11.5, even more preferably less than 10. The pH of the polishing composition of the present disclosure can be adjusted using component C or a known pH adjuster. In the present disclosure, the pH is a value measured by the method described in the Examples.

[0053] The polishing composition of the present disclosure can be produced, for example, by blending components A and B, and, optionally, water, components C, D, and other components, using a known method. That is, the polishing composition of the present disclosure can be produced, for example, by blending at least components A and B. Therefore, in another aspect, the present disclosure relates to a method for producing a polishing composition, comprising blending at least components A and B. In the present disclosure, "blending" includes mixing components A and B, and, if necessary, water, components C, D, and other components simultaneously or in any order. The blending can be carried out using, for example, a stirrer such as a homomixer, homogenizer, ultrasonic disperser, wet ball mill, or bead mill. The preferred amounts of each component in the method for producing a polishing composition of the present disclosure can be the same as the preferred contents of each component in the polishing composition of the present disclosure.

[0054] In the present disclosure, the "content of each component in the polishing composition" refers to the content of each component at the time of use, that is, at the time when the polishing composition begins to be used for polishing.

[0055] The polishing liquid composition of the present disclosure may be produced as a concentrate from the viewpoint of storage and transportation, and diluted at the time of use. The dilution ratio is preferably 2 times or more, more preferably 10 times or more, even more preferably 30 times or more, and even more preferably 50 times or more from the viewpoint of production and transportation costs, and is preferably 300 times or less, more preferably 250 times or less, even more preferably 200 times or less, and even more preferably 150 times or less from the viewpoint of storage stability. The polishing liquid composition concentrate of the present disclosure can be used by diluting it with water so that the contents of each component are the above-mentioned contents (i.e., the contents at the time of use) at the time of use. In the present disclosure, the "time of use" of the polishing liquid composition concentrate refers to the diluted state of the polishing liquid composition concentrate.

[0056] [Polishing liquid kit] In one aspect, the present disclosure relates to a polishing liquid kit (hereinafter also referred to as the "kit of the present disclosure") for producing the polishing liquid composition of the present disclosure. The kit of the present disclosure can provide a polishing liquid composition that can simultaneously improve the removal rate and suppress a decrease in the removal rate during continued use of a polishing pad, even with a low content of silica particles. In one or more embodiments, the kit of the present disclosure includes a polishing liquid kit containing a solution containing component A and component B. The solution may contain the above-mentioned components C, D, and other components as needed. The solution may be diluted with water as needed before use.

[0057] [Silicon substrate polishing method] In one aspect, the present disclosure relates to a method for polishing a silicon substrate (hereinafter also referred to as the "polishing method of the present disclosure"), which includes a step of polishing a silicon substrate to be polished using the polishing liquid composition of the present disclosure (hereinafter also referred to as the "polishing step"). According to the polishing method of the present disclosure, since the polishing liquid composition of the present disclosure is used, even if the content of silica particles is low, it is possible to achieve both an improvement in the polishing rate and suppression of a decrease in the polishing rate with continued use of the polishing pad.

[0058] In one or more embodiments, the polishing step in the polishing method of the present disclosure is a step of supplying the polishing liquid composition of the present disclosure to a surface to be polished of a silicon substrate to be polished, bringing a polishing pad into contact with the surface to be polished, and moving at least one of the polishing pad and the silicon substrate to be polished to perform polishing.

[0059] When a polishing process is performed in multiple stages, the polishing process using the polishing composition of the present disclosure is preferably performed in the second stage or later, and more preferably in the final polishing process or finish polishing process. In this case, separate polishing machines may be used for each stage to avoid contamination with the abrasive or polishing composition from the previous process. When separate polishing machines are used, it is preferable to clean the silicon substrate to be polished after each polishing process. Furthermore, the polishing composition of the present disclosure can also be used in circulating polishing in which the used polishing liquid is reused. The polishing machine is not particularly limited, and known polishing machines for substrate polishing can be used.

[0060] The polishing pad used in the polishing step is not particularly limited as long as it can be used continuously, but from the viewpoint of suppressing the decrease in the polishing rate during continuous use of the polishing pad, a polishing pad having a surface member containing a urethane resin can be preferably used. As the polishing pad, a suede type, a nonwoven fabric type, a polyurethane closed cell type, or a two-layer type in which these are laminated can be used, and a suede type polishing pad can be preferably used. In one or more embodiments, the suede-type polishing pad may include a polishing pad having a foam layer (surface member) and a base layer, the foam layer (surface member) containing a urethane resin such as a polyurethane elastomer. In one or more embodiments, the foam layer has spindle-shaped pores relative to the base layer. The compressibility of the foam layer may be, for example, 2.5% to 20%. The compressibility can be measured using a compression tester based on the compressibility measurement method described in Japanese Industrial Standards (JIS) L1096. Examples of the base layer include polyethylene terephthalate (PET) film and polyester film. The Asker hardness of the polishing pad may be, for example, 50 degrees to 100 degrees.

[0061] From the viewpoint of achieving both improved polishing rate and extended pad life, the average pore size of the surface member of the polishing pad is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 90 μm or less, even more preferably 15 μm or more and 80 μm or less, and even more preferably 20 μm or more and 70 μm or less.

[0062] The polishing load in the polishing step is preferably 3 kPa or more, more preferably 4 kPa or more, and even more preferably 5 Pa or more from the viewpoint of suppressing a decrease in the polishing rate during continued use of the polishing pad and ensuring the polishing rate, and is preferably 20 kPa or less, more preferably 18 kPa or less, and even more preferably 16 kPa or less from the viewpoint of improving surface quality. In this disclosure, the polishing load refers to the pressure of the platen applied to the polishing surface of the substrate to be polished during polishing. The polishing load can be adjusted by applying air pressure or a weight to at least one of the platen and the substrate to be polished.

[0063] In the polishing step, the supply rate of the polishing composition of the present disclosure is set to 1 / cm of the substrate to be polished from the viewpoint of ensuring the polishing rate and improving the surface quality. 2 The flow rate is preferably 0.05 to 15 mL / min, more preferably 0.06 to 10 mL / min, even more preferably 0.07 to 1 mL / min, and even more preferably 0.07 to 0.5 mL / min.

[0064] In the polishing step, the temperature of the polishing composition and the surface temperature of the polishing pad are preferably 15° C. or higher and 40° C. or lower, from the viewpoint of achieving both an improved polishing rate and good surface quality.

[0065] The polishing composition of the present disclosure can be supplied to a polishing machine by, for example, continuous supply using a pump or the like. When supplying the polishing composition to a polishing machine, in addition to a method of supplying it as a single liquid containing all components, it can also be divided into a plurality of blending component liquids and supplied as two or more liquids, taking into consideration the stability of the polishing composition, etc. In the latter case, the plurality of blending component liquids are mixed, for example, in the supply pipe or on the substrate to be polished, to produce the polishing composition of the present disclosure.

[0066] [Method of manufacturing semiconductor substrate] In another aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate (hereinafter also referred to as the "semiconductor substrate manufacturing method of the present disclosure"), which includes a step of polishing a silicon substrate to be polished using the polishing liquid composition of the present disclosure (hereinafter also referred to as the "polishing step") and a step of cleaning the polished silicon substrate (hereinafter also referred to as the "cleaning step"). According to the semiconductor substrate manufacturing method of the present disclosure, by using the polishing liquid composition of the present disclosure, even with a low content of silica particles, it is possible to achieve both an improvement in the removal rate and suppression of a decrease in the removal rate with continued use of the polishing pad, thereby enabling high-quality semiconductor substrates to be manufactured at high yield, high productivity, and low cost.

[0067] When the silicon substrate to be polished is a single crystal silicon substrate, the polishing step in the semiconductor substrate manufacturing method of the present disclosure can include, for example, a lapping (rough polishing) step of planarizing the single crystal silicon substrate obtained by slicing a single crystal silicon ingot into a thin disk, and a finish polishing step of etching the lapped single crystal silicon substrate and then mirror-finishing the surface of the single crystal silicon substrate. From the viewpoint of achieving both an improvement in the polishing rate and an improvement in the surface quality, the polishing composition of the present disclosure is more preferably used in the finish polishing step.

[0068] When the silicon substrate to be polished is a polysilicon substrate, the polishing step in the semiconductor substrate manufacturing method of the present disclosure can include, for example, a step of removing irregularities in the polysilicon film to planarize a substrate in which a polysilicon film is formed by chemical vapor deposition (CVD) on a silicon substrate having a silicon dioxide film and a silicon nitride film, and a step of simultaneously polishing and planarizing the silicon dioxide film, silicon nitride film, and polysilicon film directly below.From the viewpoint of achieving both improved polishing rate and improved surface quality, the polishing composition of the present disclosure is more preferably used in the step of removing irregularities in the polysilicon film to planarize the substrate.

[0069] The polishing step in the semiconductor substrate manufacturing method of the present disclosure can be performed under the same conditions as the polishing step in the polishing method of the present disclosure described above.

[0070] In one or more embodiments, the method for manufacturing a semiconductor substrate according to the present disclosure may include a dilution step of diluting the concentrate of the polishing liquid composition according to the present disclosure prior to the polishing step. The diluent may be, for example, water.

[0071] In the cleaning step of the semiconductor substrate manufacturing method of the present disclosure, inorganic cleaning is preferably performed from the viewpoint of reducing residues on the silicon substrate surface. Examples of cleaning agents used in inorganic cleaning include inorganic cleaning agents containing at least one selected from hydrogen peroxide, ammonia, hydrochloric acid, sulfuric acid, hydrofluoric acid, and ozone water.

[0072] In one or more embodiments, the semiconductor substrate manufacturing method of the present disclosure can further include, after the cleaning step, a step of rinsing the cleaned silicon substrate with water and drying it. [Example]

[0073] Hereinafter, the present disclosure will be described in more detail with reference to examples, but these are merely illustrative examples and the present disclosure is not limited to these examples.

[0074] 1. Preparation of Polishing Composition The silica particles (component A) shown in Table 1, the basic nitrogen-containing water-soluble polymer (component B) shown in Table 1, the nonionic water-soluble polymer (component C) shown in Table 1, ammonia (component D), and ultrapure water were mixed and stirred to obtain polishing liquid compositions of Examples 1 to 3, Comparative Examples 1 and 2, and Reference Example 1. The content of each component in Table 1 is the content (mass % or ppm, active ingredient) of each component at the time of use of the polishing liquid composition. The content of ultrapure water is the remainder excluding components A, B, C, and D.

[0075] The following components A, B, C, and D were used to prepare each polishing composition. (Component A) Colloidal silica [average primary particle size 25 nm, average secondary particle size 49 nm, degree of association 2.0] Colloidal silica [average primary particle size 35 nm, average secondary particle size 70 nm, degree of association 2.0] (Component B) Glycidol-modified polyallylamine (modification ratio 1.5) [Nittobo Medical Co., Ltd., weight-average molecular weight 30,000] (Non-ingredient B) PEI (polyethyleneimine) [Nippon Shokubai Co., Ltd., SP-200, weight-average molecular weight 10,000] (Component C) PEG (polyethylene glycol) [NOF Corporation, PEG #6000, weight-average molecular weight 6000] HEC (hydroxyethyl cellulose) [Sumitomo Seika Chemicals, SE400, weight-average molecular weight 250,000] HEC (hydroxyethyl cellulose) [Sumitomo Seika Chemicals, CF-V, weight-average molecular weight 800,000] (Component D) Ammonia [28% by mass ammonia water, Kishida Chemical Co., Ltd., special grade reagent]

[0076] 2.Measuring methods for various parameters (1) Measurement of the average primary particle size of silica particles (component A) The average primary particle diameter (nm) of component A is calculated by the BET (nitrogen adsorption) method. 2 / g) was calculated using the following formula. Average primary particle diameter (nm)=2727 / S

[0077] The specific surface area S of component A was measured by the nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device "Flowsorb III2305", manufactured by Shimadzu Corporation) after carrying out the following [pretreatment]. Approximately 0.1 g of the measurement sample was weighed out to four decimal places into a measuring cell, and the sample was dried for 30 minutes in an atmosphere at 110°C immediately before measuring the specific surface area. [Preprocessing] (a) Adjust the pH of the slurry of component A to 2.5±0.1 with an aqueous solution of nitric acid. (b) The slurry of component A adjusted to pH 2.5±0.1 is placed in a petri dish and dried in a hot air dryer at 150°C for 1 hour. (c) After drying, the obtained sample is finely crushed in an agate mortar. (d) The crushed sample is suspended in ion-exchanged water at 40°C and filtered through a membrane filter with a pore size of 1 μm. (e) The filtered material on the filter is washed five times with 20 g of ion-exchanged water (40°C). (f) The filter with the filtrate attached is placed in a petri dish and dried in an atmosphere of 110°C for 4 hours. (g) The dried filtrate (component A) was taken out, being careful not to mix in any filter debris, and finely crushed in a mortar to obtain a measurement sample.

[0078] (2) Average secondary particle size of silica particles (component A) The average secondary particle diameter (nm) of component A was measured by adding an abrasive to ion-exchanged water so that the concentration of component A was 0.25% by mass, and then placing the resulting aqueous dispersion in a disposable sizing cuvette (a 10 mm polystyrene cell) to a height of 10 mm from the bottom, using dynamic light scattering (apparatus name: Zetasizer Nano ZS, manufactured by Sysmex Corporation).

[0079] (3) Measurement of the weight-average molecular weight of water-soluble polymers The weight-average molecular weight of the water-soluble polymers (component B, component C) was calculated based on peaks in a chromatogram obtained by applying gel permeation chromatography (GPC) under the following conditions. <Basic nitrogen atom-containing water-soluble polymer (ingredient B)> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: α-M + α-M Eluent: 0.15mol / L Na2SO4,1%CH3COOH / water Flow rate: 1.0mL / min Column temperature: 40℃ Detector: Shodex RI SE-61 differential refractive index detector Standard material: monodisperse pullulan with known molecular weight <Nonionic water-soluble polymer (ingredient C)> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: GMPWXL + GMPWXL (anion) Eluent: 0.2M phosphate buffer / CH3CN=9 / 1 Flow rate: 0.5mL / min Column temperature: 40℃ Detector: Shodex RI SE-61 differential refractive index detector Standard: Monodisperse polyethylene glycol with known molecular weight

[0080] (4) Glycidol modification rate The glycidol modification rate is 13 C-NMR was used to determine the <Measurement conditions> Sample: 200 mg of glycidol-modified polyallylamine dissolved in 0.6 mL of heavy water Equipment used: 400MHz 13 C-NMR (Agilent Technologies "Agilent 400-MR DD2") Measurement conditions: 13 C-NMR measurement, pulse interval time 5 seconds, tetramethylsilane as the standard peak (σ: 0.0 ppm) Accumulation count: 5000 times Each peak range used for integration: A: 71.0 to 72.3 ppm (integrated value of the peak of C bonded to the secondary hydroxyl group of glycidol reacted with the amino group) B: 32.0 to 41.0 ppm (integrated value of the peak of the main chain C of allylamine) <Glycidol modification rate> The glycidol modification rate (ratio of glycidol equivalents to amino group equivalents) is calculated using the following formula. Glycidol modification ratio (equivalent ratio) = 2A / B

[0081] (5) pKa measurement Using an HM-41K pH meter (Toa DKK Corporation), an aqueous solution of component B adjusted to 1 M was subjected to potentiometric titration with 0.1 M hydrochloric acid at room temperature. The pKa was calculated from the obtained titration curve.

[0082] (6) pH of the polishing composition The pH of the polishing composition at 25°C was measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and was the value measured 1 minute after the electrode of the pH meter was immersed in the polishing composition.

[0083] 3. Evaluation of the polishing compositions of Examples 1 to 3, Comparative Examples 1 and 2, and Reference Example 1 (1) Polishing method etc. Each polishing composition was filtered with a filter (compact cartridge filter "MCP-LX-C10S", manufactured by Advantech Co., Ltd.) immediately before polishing, and the following silicon substrates were subjected to finish polishing and cleaning under the following polishing conditions. <Silicon substrate to be polished> Single-crystal silicon substrate [200 mm diameter silicon single-sided mirror-finished substrate, conductivity type: P, crystal orientation: 100, resistivity: 0.1 Ω·cm or more but less than 100 Ω·cm] The single crystal silicon substrate was previously subjected to rough polishing using a commercially available polishing composition (GLANZOX 1302, manufactured by Fujimi Inc.). After rough polishing, the single crystal silicon substrate was subjected to finish polishing and had a haze of 2 to 3 ppm.

[0084] <Finishing polishing conditions> Polishing machine: Single-sided 8-inch polishing machine "GRIND-X SPP600s" (manufactured by Okamoto Kogyo) Polishing pad: Suede pad (manufactured by FILWEL, Asker hardness: 66, thickness: 1.45 mm, nap length: 500 μm, average pore size: 60 μm) Polishing load: 9.8kPa Plate rotation speed: 60 rpm Polishing time: 5 minutes Supply rate of polishing liquid composition: 100g / min (1cm of substrate to be polished) 2 (0.32 mL / min per minute) Temperature of polishing composition: 23°C Carrier rotation speed: 62 rpm

[0085] <Measurement of surface roughness (haze) of silicon substrate> The value (DWO haze) measured using a surface roughness measuring device "Surfscan SP1-DLS" (KLA Tencor) in a dark field wide grazing incidence channel (DWO) was used.

[0086] <Cleaning method> After the finish polishing, the silicon substrate was subjected to ozone cleaning and dilute hydrofluoric acid cleaning as follows. For the ozone cleaning, an aqueous solution containing 20 ppm ozone was sprayed from a nozzle at a flow rate of 1 L / min toward the center of the silicon substrate rotating at 600 rpm for 3 minutes. The ozone water was kept at room temperature during this process. Next, dilute hydrofluoric acid cleaning was performed. For the dilute hydrofluoric acid cleaning, an aqueous solution containing 0.5 mass% ammonium hydrogen fluoride (special grade, Nakarai Tesque, Inc.) was sprayed from a nozzle at a flow rate of 1 L / min toward the center of the silicon substrate rotating at 600 rpm for 6 seconds. Two sets of the above ozone cleaning and dilute hydrofluoric acid cleaning were performed, and finally, spin drying was performed. For spin drying, the silicon substrate was rotated at 1,500 rpm.

[0087] (2) Evaluation of polishing speed The weight of each silicon substrate before and after polishing was measured using a precision balance (Sartorius "BP-210S"). The resulting weight difference was divided by the density, area, and polishing time of the silicon substrate to determine the single-side polishing rate per unit time, and the polishing rates for the second, fifth, and eighth silicon substrates were calculated. The weight of the silicon substrate after polishing refers to the weight of the silicon substrate after the above-mentioned finish polishing and cleaning.

[0088] [Table 1]

[0089] As shown in Table 1, the polishing liquid compositions of Examples 1 to 3 had a component A content of 0.1 mass % or less, a mass ratio B / A of 0.07 or more, and a sufficient amount of water-soluble polymer containing basic nitrogen atoms (component B) relative to the silica particles (component A), so that even with a low silica particle content, the polishing rate was higher than in Comparative Example 1, and the decrease in polishing rate during continued use of the polishing pad was suppressed more than in Comparative Example 2 and Reference Example 1. This is thought to enable increased productivity, such as a high polishing rate, reduced dressing frequency, and a longer polishing pad life, while reducing the costs of using and disposing of the polishing liquid. [Industrial Applicability]

[0090] The polishing composition of the present disclosure is useful, in particular, as a polishing composition used in the production of silicon substrates, because it can improve the polishing rate and suppress a decrease in the polishing rate during continued use of the polishing pad, even when the content of silica particles is low.

Claims

1. Contains the following component A and the following component B, The content of component A is 0.1% by mass or less, the mass ratio B / A of the content of component B to the content of component A is 0.07 or more; A polishing composition having a pH of more than 8.5 and not more than 14. Component A: Silica particles Component B: A water-soluble polymer containing basic nitrogen atoms, at least some of which contain heteroatoms (excluding basic nitrogen atoms) at positions selected from the β-, γ-, and δ-positions, the polymer containing allylamine-derived structural units, and at least some of the amino groups in the allylamine-derived structural units having sterically shielding groups.

2. 2. The polishing composition according to claim 1, wherein at least a portion of the amino groups in the structural units derived from allylamine are secondary amino groups or tertiary amino groups containing a hydrocarbon group having 2 to 11 carbon atoms and a heteroatom.

3. 3. The polishing composition according to claim 1, wherein Component B is a reaction product of polyallylamine and a glycidol derivative.

4. A method for polishing a silicon substrate, comprising the step of polishing a silicon substrate to be polished with the polishing composition according to claim 1 .

5. A step of polishing a silicon substrate to be polished using the polishing composition according to any one of claims 1 to 3; and cleaning the polished silicon substrate.

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