JP7599503B2 - Silicon substrate polishing - Google Patents

Description

This disclosure relates to polishing silicon substrates and to a method for adjusting the polishing rate of the silicon substrate and the surface quality of the substrate after polishing.

In recent years, the growing demand for higher storage capacity of semiconductor memories has led to the miniaturization of design rules for semiconductor devices. As a result, the depth of focus in photolithography used in the manufacturing process of semiconductor devices has become shallower, and the demands for reduced defects and smoothness of silicon substrates (bare wafers) have become increasingly strict.

To improve the quality of silicon substrates, polishing of silicon substrates is carried out in multiple stages. In particular, the final polishing stage aims to suppress surface roughness (haze) and to suppress surface defects (LPD: Light Point Defects) such as particles, scratches, and pits by improving the wettability (hydrophilicity) of the silicon substrate surface after polishing.

The allowable size of surface defects on silicon substrate surfaces is getting smaller every year, and these defects are usually measured by irradiating the substrate surface with laser light and detecting the scattered light. Therefore, in order to measure smaller defects, it is necessary to reduce the surface roughness (haze) of the silicon substrate and improve the signal-to-noise ratio when measuring defects.

As a polishing composition used for the finish polishing, a polishing composition for chemical mechanical polishing using colloidal silica and an alkaline compound is known.
For example, Japanese Patent Application Laid-Open No. 2004-128089 reports a polishing composition containing a water-soluble polymer compound such as hydroxyethyl cellulose or polyethylene oxide as a polishing composition aimed at improving the haze level.
Japanese Patent Application Laid-Open No. 2008-53415 reports a polishing composition containing a water-soluble polymer compound having a nitrogen-containing group, such as polyvinylpyrrolidone and poly-N-vinylformamide, as a polishing composition intended to reduce the number of surface defects (LPDs).

Also, a method for polishing a silicon substrate in multiple steps has been proposed.
For example, Japanese Patent Application Laid-Open No. 2015-185672 proposes a method for polishing a silicon substrate in which the relationship between the concentration of a water-soluble polymer in each polishing slurry used in a multi-stage polishing process and the weight-average molecular weight is specified.
Japanese Patent Application Laid-Open No. 2015-185674 proposes a method for polishing a silicon substrate, which specifies the relationship between the concentration of abrasive grains in each polishing slurry used in a multi-stage polishing process and the volume average particle diameter.
Japanese Patent Application Laid-Open No. 2016-4953 proposes a method for polishing a silicon substrate in which the relationship between the relative hazes of the polishing slurries used in the two-stage polishing process is specified.
Japanese Patent Application Laid-Open No. 2017-183478 proposes a polishing method for a silicon substrate, in which a pre-polishing step, a rinsing step, and a finish polishing step are performed in that order, and the relationship between the hydrophilic parameter of the polishing liquid composition used in the pre-polishing step and the hydrophilic parameter of the rinse agent used in the rinsing step is specified.
International Publication No. 2017/169154 proposes a polishing composition set that specifies the values of the hydrophilicity parameter and finishing accuracy parameter of the polishing composition used in the pre-polishing process, and the value of the polishing processability parameter of the polishing composition used in the finish polishing process.
The water-soluble polymers used in the polishing compositions described in the above five documents are hydroxyethyl cellulose and polyvinylpyrrolidone.

In one aspect, the present disclosure relates to a method for adjusting the polishing rate of a silicon substrate and the surface quality of the substrate after polishing by changing the content ratio of component A to component B using a polishing liquid composition containing at least one component selected from the group consisting of an amino group-containing water-soluble polymeric compound (component A) and a nonionic water-soluble polymeric compound (component B) having a pKa of 5 or more and 8.5 or less (hereinafter also referred to as the "adjustment method of the present disclosure").

In one aspect, the present disclosure relates to a method for polishing a silicon substrate, comprising a finish polishing step 2 for performing a finish polishing of the silicon substrate, and a finish polishing step 1 which is a polishing step preceding the finish polishing step 2, and in which the finish polishing step 1 and the finish polishing step 2 are performed in this order, in which the polishing liquid composition used in the finish polishing steps 1 and 2 contains at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B) having a pKa of 5 to 8.5, inclusive, the polishing liquid composition contains silica particles (component C), and polishing is performed with a polishing liquid composition in which the ratio of the content of component A to the total content of components A and B is 50% by mass or more, and in the finish polishing step 2, polishing is performed with a polishing liquid composition in which the ratio of the content of component B to the total content of components A and B is 50% by mass or more (hereinafter also referred to as the "polishing method of the present disclosure").

In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, comprising performing the adjustment method of the present disclosure or the polishing method of the present disclosure.

In order to reduce surface defects, colloidal silica with smaller particle size is used in the polishing liquid used in the finish polishing, but the polishing speed tends to be slower, and there is a problem in improving the polishing speed.
However, in polishing using the polishing compositions disclosed in JP-A-2004-128089 and JP-A-2008-53415, the removal rate is not sufficient.
In addition, the multi-stage polishing methods for silicon substrates disclosed in JP 2015-185672 A, JP 2015-185674 A, JP 2016-4953 A, JP 2017-183478 A, and WO 2017/169154 all aim to achieve a high-quality polished surface, such as improving surface smoothness and suppressing the occurrence of microdefects, and there is no mention of the polishing rate.

The present disclosure provides a method for adjusting the polishing rate of a silicon substrate and the surface quality of the substrate after polishing.

According to the present disclosure, in one aspect, in polishing a silicon substrate, the polishing rate and the substrate surface quality after polishing (e.g., substrate surface roughness (haze)) can be improved.

Although the details of the mechanism by which the effects of the present disclosure are exerted are not clear, it is presumed as follows.
The amino group-containing water-soluble polymer (component A) having a pKa of 5 or more and 8.5 or less has low cationicity, and adsorbs to the silica particles (component C) and the silicon substrate to be polished mainly by the van der Waals force of the whole molecule, rather than by electrostatic interaction with the amino groups, thereby suppressing the electrostatic repulsion between the silica abrasive grains and the silicon substrate. Therefore, it is possible to reduce the surface roughness derived from the rough polishing process and remove surface defects by realizing a high polishing rate without newly generating surface defects such as scratches due to the aggregation of silica resulting from electrostatic interaction.
On the other hand, the nonionic water-soluble polymer (component B) is adsorbed to the silicon substrate surface, and hydrophilic groups such as alkylene oxide and hydroxyl groups protrude from the silicon substrate surface, thereby suppressing excessive corrosion caused by alkali and suppressing the approach of silica abrasive grains, i.e., improving the quality of the substrate surface after polishing (e.g., reducing haze, etc.).
Both components are believed to be adsorbed primarily by van der Waals forces, and since their adsorption forces are thought to be approximately the same, they do not inhibit each other's adsorption, but are adsorbed to the silica particles (component C) or the silicon substrate to be polished depending on the ratio of components A and B in the polishing liquid.
As a result, it is believed that the effects of components A and B can be expressed according to the ratio of the adsorption amounts, i.e., the ratio of components A and B, without inhibiting the effect of component A of improving the polishing rate and the effect of component B of improving the surface quality, and the polishing rate and surface quality of the substrate can be freely adjusted.
However, the present disclosure need not be construed as being limited to these mechanisms.

[Silicon substrate to be polished]
In one or more embodiments, the polishing in the adjusting method or polishing method of the present disclosure is polishing of a silicon substrate, and in one or more embodiments, is polishing of a silicon substrate to be polished in a manufacturing method of a semiconductor substrate. In one or more embodiments, the silicon substrate to be polished in the adjusting method or polishing method of the present disclosure is a silicon substrate or the like, and in one or more embodiments, a single crystal silicon substrate is included.

[Polishing composition]
The polishing liquid composition in the preparation method or polishing method of the present disclosure (hereinafter also referred to as the “polishing liquid composition of the present disclosure”) contains at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B), each having a pKa of 5 or more and 8.5 or less.
The polishing composition of the present disclosure may contain polishing abrasive grains as necessary. In one or more embodiments, the polishing abrasive grains may include silica particles.
The polishing liquid composition for the "final polishing step 1" in the polishing method of the present disclosure preferably contains abrasive grains from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing. The polishing liquid composition for the "final polishing step 2" in the polishing method of the present disclosure may or may not contain abrasive grains.

In the present disclosure, improving the surface quality of the substrate after polishing, in one or more embodiments, is reducing the surface roughness (haze) of the substrate after polishing.

[Amino group-containing water-soluble polymer having a pKa of 5 or more and 8.5 or less (Component A)]
The polishing composition of the present disclosure may contain an amino group-containing water-soluble polymer (hereinafter also referred to as "Component A") having a pKa of 5 or more and 8.5 or less. Component A may exert an effect of suppressing aggregation of polishing grains and improving the polishing rate. In the present disclosure, "water-soluble" means having a solubility of 0.5 g/100 mL or more in water (20° C.), preferably a solubility of 2 g/100 mL or more.

From the viewpoint of improving the polishing rate, the pKa of Component A is 5 or more, preferably 5.5 or more, more preferably 5.9 or more, even more preferably 6.3 or more, even more preferably 6.8 or more, even more preferably 7.3 or more, even more preferably 7.5 or more, and even more preferably 7.7 or more, and from the viewpoint of improving the surface quality, it is 8.5 or less, preferably 8.3 or less, more preferably 8.1 or less, and even more preferably 8 or less.
When component A is component A1 described below, the pKa of component A is preferably within the above range.
Furthermore, when component A is component A2 described later, from the viewpoint of improving the polishing rate, the pKa of component A is more preferably 6.6 or more, more preferably 6.9 or more, and more preferably 7.1 or more, and from the viewpoint of improving the surface quality, it is more preferably 7.8 or less, more preferably 7.6 or less, and more preferably 7.4 or less.

From the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, it is preferable that component A contains one or more monomer-derived structural units selected from allylamine and diallylamine. From the viewpoint of availability, in one or more embodiments, component A is preferably an amino group-containing water-soluble polymer containing a structural unit derived from allylamine (hereinafter also referred to as "component A1"), and in one or more embodiments, it is preferably an amino group-containing water-soluble polymer containing a structural unit derived from diallylamine (hereinafter also referred to as "component A2").

(Component A1: Amino group-containing water-soluble polymer containing allylamine-derived structural units)
In one or more embodiments, at least a part of the amino groups in the allylamine-derived structural unit preferably has a steric shielding group from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, and from the viewpoint of availability. In the present disclosure, the steric shielding group refers to a three-dimensional (bulky) substituent that can shield the nitrogen atom of the amino group of component A to suppress cationization, i.e., lower the pKa. From the same viewpoint, the amino group having the steric shielding group is preferably a secondary amino group or a tertiary amino group containing a hydrocarbon group having 3 to 11 carbon atoms and having a hydroxyl group. The number of carbon atoms of the hydrocarbon group is preferably 3 or more from the viewpoint of improving the shielding property of the amino group (suppressing the cationization of the nitrogen atom of the amino group) and from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, and from the viewpoint of improving water solubility and availability, it is preferably 11 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 4 or less.

In one or more embodiments, the amino group having a steric 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 part of the amino groups of component A1 are modified by a glycidol derivative to become an amino group having a steric shielding group. The equivalent of the glycidol derivative 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, even more preferably 1.3 or more, even more preferably 1.5 or more, even more preferably 1.7 or more, and 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, and even more preferably 2 or less.

In the present disclosure, the glycidol modification rate is a value measured by the method described in the Examples using ¹³ 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 and the number of moles of the glycidol derivative used as the reaction raw material.
(2) The nitrogen content N (mass %) of the reaction product of a glycidol derivative and an 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 polymer/14)/molecular weight of glycidol derivative, and B=N/14.

Examples of the glycidol derivative include glycidol and alkyl glycidyl ether, and glycidol is preferred from the viewpoint of availability and from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing. From the viewpoint of availability, the alkyl group of the alkyl glycidyl ether is preferably an alkyl group having 1 to 8 carbon atoms, and examples of the alkyl group include methyl, ethyl, propyl, butyl, and 2-ethylhexyl. Examples of the alkyl glycidyl ether include methyl glycidyl ether and 2-ethylhexyl glycidyl ether.

In one or more embodiments, component A1 may be a polyallylamine in which at least some of the amino groups have sterically shielding groups, and in one or more embodiments, a reaction product of a polyallylamine with a glycidol derivative.

In one or more embodiments, Component A1 may be a compound containing a structural unit represented by the following formula (I) (glycidol-modified polyallylamine).

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 a 1-molar or 2-molar adduct of glycidol, and in one or more embodiments, examples thereof include -CH ₂ CH(OH)CH ₂ (OH), -CH ₂ CH(OH)CH ₂ O-CH ₂ CH(OH)CH ₂ (OH), etc.

(Component A2: Amino group-containing water-soluble polymer containing a diallylamine-derived structural unit)
In one or more embodiments, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, at least a part of the amino groups in the diallylamine-derived constitutional unit preferably has an electron-withdrawing group at the β-position or γ-position of the amino group. Examples of the electron-withdrawing group include a group represented by the following formula (II).

In one or more embodiments, Component A2 includes a compound containing a diallylamine-derived structural unit and a sulfur dioxide-derived structural unit, for example, a compound containing a structural unit represented by the following formula (III).

In formula (III), R ³ is an alkyl group having 1 to 3 carbon atoms which may have a hydroxyl group. From the viewpoints of availability and economy, R ³ is preferably a methyl group. Also, n+m=1, and n and m are 0 or 1. From the same viewpoint, a compound in which m=1 and n=0 is preferred. A mixture of a compound in which m=1 and n=0 and a compound in which m=0 and n=1 may also be used.

In one or more embodiments, Component A2 includes a compound containing a structural unit represented by the following formula (IV), such as a methyldiallylamine/sulfur dioxide copolymer.

From the viewpoint of improving the polishing rate, the weight average molecular weight of component A is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and even more preferably 2,000 or more, and from the viewpoint of adjusting the polishing rate and the substrate surface quality after polishing, it is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 12,000 or less. The weight average molecular weight of component A in this disclosure can be measured, for example, by the method described in the Examples.

When component A is component A1, from the viewpoint of improving the polishing rate, the weight average molecular weight of component A is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, even more preferably 2,000 or more, preferably 3,000 or more, more preferably 5,000 or more, and even more preferably 6,000 or more, and from the viewpoint of adjusting the polishing rate and the substrate surface quality after polishing, it is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, and even more preferably 12,000 or less.

When component A is component A2, from the viewpoint of improving the polishing rate, the weight average molecular weight of component A is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and even more preferably 2,000 or more, and from the viewpoint of adjusting the polishing rate and the substrate surface quality after polishing, it is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, even more preferably 15,000 or less, even more preferably 12,000 or less, even more preferably 10,000 or less, even more preferably 7,000 or less, even more preferably 5,000 or less, and even more preferably 4,000 or less.

From the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, the content of component A in the polishing composition of the present disclosure may be, in one or more embodiments, 10 ppm by mass or more, 20 ppm by mass or more, or 30 ppm by mass or more, and from the same viewpoint, in one or more embodiments, 200 ppm by mass or less, 150 ppm by mass or less, or 120 ppm by mass or less. In this disclosure, 1% by mass is 10,000 ppm by mass (the same applies below).

[Nonionic water-soluble polymer (component B)]
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 B") from the viewpoint of improving the surface quality of the polished substrate. From the same viewpoint, Component B 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 B may be one type or a combination of two or more types.

Examples of component B include at least one selected from polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyethylacrylamide, and polyethylene glycol having a weight average molecular weight of 300 or more and 1,000 or less, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing.
The alkyl group of the polyglycerin 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, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, and from the viewpoint of suppressing foaming of the polishing liquid. The alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group. The average polymerization degree of the glycerin unit of the polyglycerin 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 improving wettability, and is 100 or less, preferably 60 or less, more preferably 45 or less, and even more preferably 25 or less, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing. Examples of the polyglycerin alkyl ether include polyglycerin lauryl ether, polyglycerin decyl ether, and polyglycerin myristyl ether.
The alkyl group of the polyglycerin 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, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, and from the viewpoint of suppressing foaming of the polishing liquid. The alkyl group may be a straight-chain alkyl group or a branched-chain alkyl group. The average degree of polymerization of the glycerin unit of the polyglycerin 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 improving wettability, and is 100 or less, preferably 60 or less, more preferably 45 or less, and even more preferably 25 or less, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing. Examples of the polyglycerin alkyl ester include polyglycerin lauryl ester, polyglycerin decyl ester, and polyglycerin myristyl ester.
From the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, the hydroxyalkyl cellulose is preferably at least one selected from hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, and hydroxybutyl cellulose, and more preferably hydroxyethyl cellulose (HEC).
Among these, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, component B is preferably at least one selected from polyglycerin, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), hydroxyethyl cellulose (HEC), and polyethylene glycol (PEG) having a weight-average molecular weight of 300 or more and 1,000 or less, and polyglycerin is more preferable.

From the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, the weight average molecular weight of Component B is preferably 300 or more, more preferably 500 or more, even more preferably 1,000 or more, even more preferably 1,500 or more, and even more preferably 2,000 or more, and from the same viewpoint and from the viewpoint of the filterability of the polishing liquid, it is preferably less than 500,000, more preferably 400,000 or less, even more preferably 300,000 or less, even more preferably 150,000 or less, even more preferably 100,000 or less, even more preferably 50,000 or less, even more preferably 20,000 or less, and even more preferably 10,000 or less.
When component B is a polyglycerin, from the same viewpoint, the weight average molecular weight of component B is preferably 1,000 or more, more preferably 1,500 or more, even more preferably 2,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less, even more preferably 6,000 or less.
When component B is polyvinyl alcohol (PVA), from the same viewpoint, the weight average molecular weight of component B is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more, and is preferably 150,000 or less, more preferably 120,000 or less, and even more preferably 100,000 or less.
When component B is polyvinylpyrrolidone (PVP), from the same viewpoint, the weight average molecular weight of component B is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 20,000 or more, and is preferably 150,000 or less, more preferably 120,000 or less, and even more preferably 100,000 or less.
When component B is hydroxyethyl cellulose (HEC), from the same viewpoint, the weight average molecular weight of component B 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.
When component B is polyethylene glycol (PEG) having a weight average molecular weight of 300 or more and 1,000 or less, the weight average molecular weight of component B is preferably 500 or more and preferably 900 or less, more preferably 800 or less, from the same viewpoint.
The weight average molecular weight of Component B can be measured by the method described in the Examples below.

In one or more embodiments, the content of component B in the polishing composition of the present disclosure, from the viewpoint of adjusting the polishing rate and the post-polishing substrate surface quality, may be 0 ppm by mass or more, 2 ppm by mass or more, 10 ppm by mass or more, 20 ppm by mass or more, 30 ppm by mass or more, 50 ppm by mass or more, or 100 ppm by mass or more, and may be 1,000 ppm by mass or less, 500 ppm by mass or less, 300 ppm by mass or less, or 200 ppm by mass or less. When component B is a combination of two or more types, the content of component B refers to the total content thereof.

The total content of components A and B in the polishing liquid composition of the present disclosure is preferably 20 ppm by mass or more, more preferably 40 ppm by mass or more, even more preferably 60 ppm by mass or more, even more preferably 80 ppm by mass or more, and even more preferably 90 ppm by mass or more, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing. From the same viewpoint, it is preferably 400 ppm by mass or less, more preferably 350 ppm by mass or less, even more preferably 300 ppm by mass or less, even more preferably 260 ppm by mass or less, even more preferably 240 ppm by mass or less, and even more preferably 220 ppm by mass or less. From the same viewpoint, the total content of component A and component B in the polishing liquid composition of the present disclosure is preferably 20 ppm by mass or more and 400 ppm by mass or less, more preferably 40 ppm by mass or more and 350 ppm by mass or less, even more preferably 60 ppm by mass or more and 300 ppm by mass or less, even more preferably 80 ppm by mass or more and 260 ppm by mass or less, even more preferably 90 ppm by mass or more and 240 ppm by mass or less, and even more preferably 90 ppm by mass or more and 220 ppm by mass or less.

[Polishing grains: silica particles (component C)]
In one or more embodiments, the polishing abrasive grains that can be contained in the polishing liquid composition of the present disclosure are silica particles (hereinafter, also referred to as "component C"). Component C can be colloidal silica, fumed silica, pulverized silica, or silica surface-modified with these. From the viewpoint of improving the polishing rate and storage stability at the same time, and from the viewpoint of improving surface quality such as reducing surface roughness (haze), surface defects and scratches, colloidal silica is preferred. Component C can be one type or a combination of two or more types.

From the viewpoint of operability, the use form of component C is preferably a slurry form. When component C contained in the polishing liquid composition of the present disclosure is colloidal silica, from the viewpoint of preventing contamination of the silicon substrate by 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.

From the viewpoint of maintaining the polishing rate, the average primary particle diameter of component C 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 adjusting the polishing rate and the surface quality of the substrate after polishing, it is preferably 50 nm or less, more preferably 45 nm or less, and even more preferably 40 nm or less. From the same viewpoint, the average primary particle diameter of component C is preferably 10 nm or more and 50 nm or less, more preferably 15 nm or more and 45 nm or less, and even more preferably 20 nm or more and 40 nm or less.
In the present disclosure, the average primary particle size of component C is calculated using the specific surface area S ( ^m2 /g) calculated by the nitrogen adsorption method (BET method). The average primary particle size value is a value measured by the method described in the Examples.

From the viewpoint of maintaining the polishing rate, the average secondary particle diameter of component C 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 adjusting the polishing rate and the surface quality of the substrate after polishing, it is preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less. From the same viewpoint, the average secondary particle diameter of component C is preferably 20 nm or more and 100 nm or less, more preferably 30 nm or more and 90 nm or less, and even more preferably 40 nm or more and 80 nm or less.
In the present disclosure, the average secondary particle size is a value measured by a dynamic light scattering (DLS) method, and is a value measured by the method described in the Examples.

From the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, the degree of association of component C is preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less, and from the same viewpoint, it is preferably 1.1 or more, more preferably 1.5 or more, and even more preferably 1.8 or more.

In the present disclosure, the degree of association of component C is a coefficient representing the shape of the silica particles and is calculated by the following formula.
Degree of association = average secondary particle size / average primary particle size

Methods for adjusting the degree of association of component C can be, for example, those described in JP-A-6-254383, JP-A-11-214338, JP-A-11-60232, JP-A-2005-060217, and JP-A-2005-060219.

The shape of component C is preferably spherical and/or cocoon-shaped in order to adjust the polishing speed and the surface quality of the substrate after polishing.

The content of component C in the polishing liquid composition of the present disclosure is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.07 mass% or more, calculated as _SiO2 , from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing. From the same viewpoint, it is preferably 2.5 mass% or less, more preferably 1 mass% or less, more preferably 0.8 mass% or less, even more preferably 0.5 mass% or less, and even more preferably 0.3 mass% or less. The content of component C in the polishing liquid composition of the present disclosure is preferably 0.01 mass% or more and 2.5 mass% or less, more preferably 0.05 mass% or more and 1 mass% or less, more preferably 0.05 mass% or more and 0.8 mass% or less, more preferably 0.05 mass% or more and 0.5 mass% or less, and even more preferably 0.07 mass% or more and 0.3 mass% or less. When component C is a combination of two or more types, the content of component C refers to the total content thereof.

The ratio of the content of component A to the content of component C in the polishing liquid composition of the present disclosure (mass ratio A/C) is preferably 0.001 or more, more preferably 0.005 or more, and even more preferably 0.008 or more, from the viewpoint of adjusting the polishing rate and the post-polishing substrate surface quality, and from the same viewpoint, is preferably 0.2 or less, more preferably 0.18 or less, and even more preferably 0.16 or less.

The ratio of the content of component B to the content of component C in the polishing liquid composition of the present disclosure (mass ratio B/C) is, from the viewpoint of adjusting the polishing rate and the post-polishing substrate surface quality, preferably 0.0005 or more, more preferably 0.001 or more, even more preferably 0.0012 or more, and preferably 0.4 or less, more preferably 0.2 or less, even more preferably 0.18 or less, and even more preferably 0.17 or less.

[water]
In one or more embodiments, the polishing liquid 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 liquid composition of the present disclosure may be, for example, the remainder of component A, component B, component C, and any optional components described below.

[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. is preferably a water-soluble nitrogen-containing basic compound from the viewpoint of achieving both an improvement in the polishing rate and storage stability, and from the viewpoint of improving the surface quality. "Basic" refers to a nitrogen-containing compound that exhibits basicity when dissolved in water. In one or more embodiments, component D is an amino group-containing water-soluble polymer having a pKa of 5 or more and 8.5 or less. This does not include the molecule (component A). Component D may be one type or a combination of two or more types.

In one or more embodiments, component D may be at least one selected from an amine compound and an ammonium compound. Examples of component D include ammonia, ammonium hydroxide, ammonium carbonate, ammonium hydrogen carbonate, 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 hydroxylamine. Among these, from the viewpoint of adjusting the polishing rate and the post-polishing substrate surface quality, component D is preferably ammonia or a mixture of ammonia and hydroxyamine, and more preferably ammonia.

When the polishing liquid composition of the present disclosure contains component D, the content of component D in the polishing liquid composition of the present disclosure is preferably 5 mass ppm or more, more preferably 10 mass ppm or more, and even more preferably 20 mass ppm or more from the viewpoint of improving the polishing rate, and is preferably 500 mass ppm or less, more preferably 300 mass ppm or less, more preferably 150 mass ppm or less, and even more preferably 100 mass ppm or less from the viewpoint of adjusting the polishing rate and the substrate surface quality after polishing. From the same viewpoint, the content of component D is preferably 5 mass ppm or more and 500 mass ppm or less, more preferably 10 mass ppm or more and 300 mass ppm or less, more preferably 20 mass ppm or more and 150 mass ppm or less, and even more preferably 20 mass ppm or more and 100 mass 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.

When the polishing composition of the present disclosure contains component D, the ratio D/C of the content of component D to the content of component C in the polishing composition of the present disclosure (mass ratio D/C) is preferably 0.002 or more, more preferably 0.01 or more, and even more preferably 0.015 or more, from the viewpoint of improving the polishing rate, and is preferably 1 or less, more preferably 0.5 or less, even more preferably 0.1 or less, and even more preferably 0.08 or less, from the viewpoint of adjusting the polishing rate and the quality of the substrate surface after polishing. From the same viewpoint, the mass ratio D/C is preferably 0.002 or more and 1 or less, more preferably 0.01 or more and 0.5 or less, more preferably 0.015 or more and 0.1 or less, and even more preferably 0.015 or more and 0.08 or less.

[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 a water-soluble polymer other than components A and B, a pH adjuster other than component D, a preservative, an alcohol, a chelating agent, an oxidizing agent, and the like.

[pH]
The pH of the polishing liquid composition of the present disclosure is more than 8.5, preferably 9 or more, more preferably 9.5 or more, and more preferably 10 or more, from the viewpoint of adjusting the polishing rate and the surface quality of the substrate after polishing, and from the same viewpoint, it is 14 or less, preferably 13 or less, more preferably 12.5 or less, more preferably 12 or less, more preferably 11.5 or less, and more preferably 11 or less. From the same viewpoint, the pH of the polishing liquid composition of the present disclosure is more than 8.5 to 14 or less, preferably 9 to 13 or less, more preferably 9.5 to 12.5 or less, more preferably 9.5 to 12 or less, more preferably 9.5 to 11.5 or less, and more preferably 10 to 11 or less. The pH of the polishing liquid composition of the present disclosure can be adjusted using component D or a known pH adjuster. In the present disclosure, the above pH is a value measured by the method described in the examples.

[pH-pKa]
From the viewpoint of adjusting the polishing rate and the post-polishing substrate surface quality, the pH of the polishing liquid composition of the present disclosure is preferably higher than the pKa of component A. From the same viewpoint, the difference between the pH and the pKa (pH-pKa) is preferably more than 0, more preferably 0.5 or more, even more preferably 1 or more, even more preferably 1.5 or more, and even more preferably 2 or more, and from the same viewpoint, is preferably 7 or less, more preferably 6 or less, even more preferably 5.5 or less, even more preferably 5 or less, and even more preferably 4.5 or less.

The polishing liquid composition of the present disclosure can be produced, for example, by blending component A and component B, and, if desired, water, component C, component D, and other components by a known method. That is, the polishing liquid composition of the present disclosure can be produced, for example, by blending at least component A and component B. Therefore, in another aspect, the present disclosure relates to a method for producing a polishing liquid composition, which includes a step of blending at least component A and component B. In the present disclosure, "blending" includes mixing component A, component B, and, if necessary, water, component C, and other components simultaneously or in any order. The blending can be performed using, for example, a stirrer such as a homomixer, homogenizer, ultrasonic disperser, wet ball mill, or bead mill. The preferred blending amount of each component in the method for producing a polishing liquid composition of the present disclosure can be the same as the preferred content of each component in the polishing liquid composition of the present disclosure described above.

In this disclosure, "the content of each component in the polishing liquid composition" refers to the content of each component at the time of use, i.e., at the time when the polishing liquid composition begins to be used for polishing.

The polishing liquid composition of the present disclosure may be manufactured as a concentrate from the viewpoint of storage and transportation, and may be 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 180 times or less, more preferably 140 times or less, even more preferably 100 times or less, and even more preferably 70 times or less from the viewpoint of storage stability. The polishing liquid composition concentrate of the present disclosure can be used by diluting with water so that the content of each component at the time of use is the above-mentioned content (i.e., the content at the time of use). In the present disclosure, the "time of use" of the polishing liquid composition concentrate refers to the state in which the polishing liquid composition concentrate is diluted.

[Adjustment method]
The adjustment method of the present disclosure is a method for adjusting the polishing rate of a silicon substrate and the surface quality of the substrate after polishing by changing the content ratio of component A and component B using the polishing liquid composition of the present disclosure described above. According to the adjustment method of the present disclosure, the effect of the polishing rate and the effect of the surface quality of the substrate can be changed by changing the content ratio of component A and component B. Therefore, "adjusting the polishing rate of a silicon substrate and the surface quality of the substrate after polishing" includes, in one or more embodiments, when polishing using the polishing liquid composition of the present disclosure, making the polishing liquid composition a composition that prioritizes the improvement of the polishing rate over the improvement of the surface quality of the substrate after polishing, and in one or more embodiments, when polishing using the polishing liquid composition of the present disclosure, making the polishing liquid composition a composition that prioritizes the improvement of the surface quality of the substrate after polishing over the improvement of the polishing rate, and in one or more embodiments, when polishing using the polishing liquid composition of the present disclosure, making the polishing liquid composition a composition that balances the improvement of the polishing rate and the improvement of the surface quality of the substrate after polishing.
In one or more other embodiments, the adjustment method of the present disclosure also includes adjusting the improvement in the polishing rate of polishing and the improvement in the surface quality of the polished substrate by polishing a silicon substrate to be polished with one or more polishing liquid compositions in which the improvement in the polishing rate and the improvement in the surface quality of the polished substrate are adjusted as described above.

When a composition is designed to prioritize improvement of the removal rate, in one or a plurality of embodiments, the ratio of component A in the polishing composition of the present disclosure can be increased.
When the ratio of component A is increased, in one or more embodiments, the ratio of component A to the total content of components A and B in the polishing composition [A/(A+B)] is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, still more preferably 90 mass% or more, still more preferably 95 mass% or more, still more preferably 98 mass% or more, and still more preferably substantially 100 mass%.
In the present disclosure, the ratio [A/(A+B)] being substantially 100% by mass in one or a plurality of embodiments may mean that component B is 0% by mass or is not intentionally added or blended.

When the composition prioritizes improving the surface quality of the polished substrate, in one or a plurality of embodiments, the ratio of component B in the polishing composition of the present disclosure can be increased.
When the ratio of component B is increased, in one or more embodiments, the ratio of component B to the total content of components A and B in the polishing composition [B/(A+B)] is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, still more preferably 90 mass% or more, still more preferably 95 mass% or more, still more preferably 98 mass% or more, and still more preferably substantially 100 mass%.
In the present disclosure, the ratio [B/(A+B)] being substantially 100% by mass in one or more embodiments may mean that component A is 0% by mass or is not intentionally added or blended.

In a case where a composition is designed to prioritize improvement of the removal rate, in one or a plurality of embodiments, the polishing composition of the present disclosure preferably contains silica particles (component C).
In the case where a composition is designed to prioritize improvement of the surface quality of the polished substrate, in one or a plurality of embodiments, a polishing composition that does not contain silica particles (component C) can also be used.

[Adjustment of the polishing process]
In one or a plurality of embodiments, the adjustment method of the present disclosure also includes adjusting an improvement in the polishing rate of polishing in the polishing step and an improvement in the surface quality of the substrate after polishing by performing polishing using two or more polishing liquid compositions in which the improvement in the polishing rate and the improvement in the surface quality of the substrate after polishing are adjusted as described above.
In one or more embodiments, in order to obtain a substrate with a certain surface quality, first, polishing is performed using a polishing composition with a high content ratio of component A, which prioritizes the improvement of the polishing rate, and then polishing is performed using a polishing composition with a high content ratio of component B, which prioritizes the improvement of the surface quality of the substrate after polishing. Thus, the preparation method of the present disclosure includes changing the content ratios of component A and component B in two or more polishing compositions, selecting a combination of polishing compositions that shortens the polishing time until a predetermined surface quality is obtained, and polishing using them. By using these polishing liquids, it is possible to increase productivity and reduce the cost of polishing.
The adjustment method of the present disclosure may include changing the total content of component A and component B in addition to changing the content ratio of component A and component B in two or more polishing liquid compositions.
The preparation method of the present disclosure may include selecting a combination of three or more polishing fluid compositions.

When two or more of the polishing compositions of the present disclosure are used in combination for polishing, the polishing can be performed by supplying two or more of the polishing compositions to one polishing platen in a switching manner. Alternatively, the polishing can be performed by changing the polishing platen for each of the two or more combinations of the polishing compositions.
A system is used in which components A and B are supplied from their respective storage containers using tubes or the like to the same polishing table, and the components are mixed and introduced into the polishing liquid before being introduced into the polishing table, and the supply amounts of components A and B are changed to continuously change the content ratio during polishing. This also falls under the case of polishing using two or more polishing liquid compositions according to the preparation method of the present disclosure.

[Method of polishing silicon substrate]
In one or a plurality of embodiments, the preparation method of the present disclosure is preferably used in a finish polishing process from the viewpoint of achieving both an improvement in the polishing rate and an improvement in the surface quality.

As a finish polishing process in which the adjustment method of the present disclosure is used, from the viewpoint of better exerting the effects of the present disclosure, a polishing process comprising a finish polishing process 2 for performing finish polishing of the silicon substrate, and a finish polishing process 1 which is a polishing process preceding the finish polishing process 2, in which the finish polishing process 1 and the finish polishing process 2 are performed in this order is preferred, and a polishing process comprising a finish polishing process 2 for performing finish polishing of the silicon substrate, and a finish polishing process 1 which is a polishing process preceding the finish polishing process 2, in which the finish polishing process 1 and the finish polishing process 2 are successively performed is more preferred.

In the final polishing step 1, it is preferable to perform polishing with a polishing liquid composition that contains silica particles (component C) and has a high ratio of the content of component A to the total content of components A and B [A/(A+B)], and in the final polishing step 2, polishing is performed with a polishing liquid composition that has a high ratio of the content of component B to the total content of components A and B [B/(A+B)].
The polishing composition used in the finish step 2 may or may not contain silica particles (component C). In addition, in the finish polishing step 2, polishing may be performed with a polishing composition containing silica particles (component C) and then with a polishing composition not containing silica particles (component C).

Therefore, in one aspect, the present disclosure provides a method for polishing a silicon substrate, comprising a finish polishing step 2 for performing finish polishing of a silicon substrate, and a finish polishing step 1 which is a polishing step prior to the finish polishing step 2, and the finish polishing step 1 and the finish polishing step 2 are performed in this order,
The polishing liquid composition used in the final polishing steps 1 and 2 contains at least one component selected from the group consisting of component A and component B, and in the final polishing step 1, the polishing liquid composition contains component C, and polishing is performed with the polishing liquid composition in which the ratio of the content of component A to the total content of components A and B is 50 mass% or more,
The present invention relates to a method for polishing a silicon substrate, in which the finish polishing step 2 is performed with a polishing composition having a content ratio of component B of 50 mass % or more relative to the total content of components A and B. According to the method for polishing a silicon substrate of this embodiment, the polishing rate and surface quality can be improved.

The proportion of the polishing composition used in the finish polishing step 1, [A/(A+B)], from the viewpoint of improving the polishing rate, is preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, still more preferably 90 mass% or more, still more preferably 95 mass% or more, still more preferably 98 mass% or more, and still more preferably substantially 100 mass%.
Furthermore, the proportion of the polishing composition used in the finish polishing step 2 [B/(A+B)] is, from the viewpoint of improving surface quality, preferably 50 mass% or more, more preferably 70 mass% or more, even more preferably 80 mass% or more, still more preferably 90 mass% or more, still more preferably 95 mass% or more, still more preferably 98 mass% or more, and still more preferably substantially 100 mass%.

In the finish polishing steps 1 and 2 of the polishing method of the present disclosure, for example, the silicon substrate to be polished can be pressed against a platen to which a polishing pad is attached, and the silicon substrate to be polished can be polished at a polishing pressure of 3 to 20 kPa. In the present disclosure, the polishing pressure refers to the pressure of the platen applied to the surface of the silicon substrate to be polished during polishing.

In the finish polishing steps 1 and 2 in the polishing method of the present disclosure, for example, the silicon substrate to be polished can be pressed against a platen to which a polishing pad is attached, and the silicon substrate to be polished can be polished with a polishing liquid composition and a polishing pad surface temperature of 15° C. to 40° C. From the viewpoint of achieving both an improvement in the polishing rate and surface quality such as a reduction in surface roughness (haze), the temperature of the polishing liquid composition and the polishing pad surface temperature are preferably 15° C. or higher or 20° C. or higher, and preferably 40° C. or lower or 30° C. or lower.

The finish polishing step 1 and the finish polishing step 2 can be performed using one polishing platen (the same polishing platen). Alternatively, the finish polishing step 1 and the finish polishing step 2 can be performed using different polishing plates, that is, the finish polishing step 2 can be performed using a polishing platen different from the polishing platen used in the finish polishing step 1.
When the finish polishing process 1 and the finish polishing process 2 are performed on the same polishing table, a system in which components A and B are supplied from their respective storage containers using tubes or the like and mixed before being introduced into the polishing liquid before being introduced into the polishing table may be used, and the supply amounts of components A and B may be changed to continuously change the content ratio during polishing.
In the final polishing step 2, when polishing with a polishing composition containing silica particles (component C) is performed followed by polishing with a polishing composition not containing silica particles (component C), the polishing can be performed on the same polishing platen. Alternatively, the step of polishing with a polishing composition not containing silica particles (component C) can be performed on a polishing platen different from the polishing platen used in the step of polishing with a polishing composition containing silica particles (component C).

[Method of manufacturing semiconductor substrate]
In one aspect, the present disclosure relates to a method for producing a semiconductor substrate (hereinafter also referred to as the "semiconductor substrate production method of the present disclosure"), which includes carrying out the preparation method of the present disclosure or the polishing method of the present disclosure. In one or more embodiments, the semiconductor substrate production method of the present disclosure can include 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 production method of the present disclosure, by using the preparation method of the present disclosure or the polishing method of the present disclosure, it is possible to achieve both an improvement in polishing rate and an improvement in surface quality, so that a high-quality semiconductor substrate can be produced at a high yield, high productivity, and low cost.

The polishing step in the semiconductor substrate manufacturing method of the present disclosure can include, for example, a lapping (rough polishing) step of planarizing a single crystal silicon substrate obtained by slicing a single crystal silicon ingot into a thin disk shape, and a finish polishing step of mirror-finishing the surface of the single crystal silicon substrate after etching the lapped single crystal silicon substrate. The preparation method of the present disclosure is more preferably used in the above-mentioned finish polishing step from the viewpoint of achieving both an improvement in the polishing rate and an improvement in the surface quality. Examples of the finish polishing step in which the preparation method of the present disclosure is used include those described above. In the polishing step in the semiconductor substrate manufacturing method of the present disclosure, polishing can be performed under the same conditions (polishing pressure, polishing composition, polishing pad surface temperature, etc.) as those in the finish polishing steps 1 and 2 in the polishing method of the present disclosure described above.

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

In the cleaning step of the semiconductor substrate manufacturing method of the present disclosure, it is preferable to perform inorganic cleaning 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.

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

When the polishing step in the semiconductor substrate manufacturing method of the present disclosure is a polishing step in which the above-mentioned final polishing step 1 and final polishing step 2 are performed in this order, the final polishing step 1 may be followed by cleaning and drying, and then the final polishing step 2 may be performed. Also, the final polishing step 2 may be performed without cleaning and drying, after the final polishing step 1 is performed. From the viewpoint of improving productivity, it is preferable to perform the final polishing step 2 without cleaning and drying, after the final polishing step 1 is performed.

The present disclosure further relates to one or more of the following embodiments.
<1> A method for adjusting the polishing rate of a silicon substrate and the surface quality of the substrate after polishing, by using a polishing composition containing at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B), each having a pKa of 5 or more and 8.5 or less, and changing the content ratio of component A to component B.
<2> The method according to <1>, which comprises using a polishing composition containing at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B), each having a pKa of 5 or more and 8.5 or less, the pH of the polishing composition being 9 or more and 12 or less, and the difference between the pH and the pKa [pH-pKa] being 2 or more and 6 or less, and changing the content ratio of component A to component B.
<3> The method according to <1> or <2>, wherein component A is at least one selected from the group consisting of a reaction product of polyallylamine with a glycidol derivative and a compound containing a structural unit represented by the above formula (III), and component B is at least one selected from the group consisting of polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyethylacrylamide, and polyethylene glycol having a weight-average molecular weight of 300 or more and 1,000 or less.
<4> The method according to any one of <1> to <3>, wherein the content of component A in the polishing composition is 0 ppm by mass or more and 200 ppm by mass or less, and the content of component B in the polishing composition is 0 ppm by mass or more and 200 ppm by mass or less.
<5> The method according to any one of <1> to <4>, wherein the weight average molecular weight of component A is 800 or more and 12,000 or less, and the weight average molecular weight of component B is 300 or more and 300,000 or less.
<6> The method according to any one of <1> to <5>, wherein the polishing composition further contains silica particles (component C).
<7> The method according to any one of <1> to <6>, wherein the content of component C in the polishing composition is 0.07 mass % or more and 0.3 mass % or less, and the silicon substrate is a single crystal silicon substrate.
<8> The method according to any one of <1> to <6>, wherein the content of component C in the polishing composition is 0.1 mass % or more and 0.8 mass % or less, and the silicon substrate is a polysilicon substrate.
<9> A method for polishing a silicon substrate, comprising a finish polishing step 2 for performing finish polishing of a silicon substrate, and a finish polishing step 1 which is a polishing step prior to the finish polishing step 2, the finish polishing step 1 and the finish polishing step 2 being performed in this order,
The polishing composition used in the finish polishing steps 1 and 2 contains at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B), each having a pKa of 5 or more and 8.5 or less;
In the final polishing step 1, polishing is performed with a polishing composition containing silica particles (component C), and the ratio of the content of component A to the total content of components A and B is 50 mass% or more,
A method for polishing a silicon substrate, wherein in the finish polishing step 2, polishing is performed with a polishing composition having a content of component B of 50 mass % or more relative to the total content of components A and B.
<10> A method for polishing a silicon substrate, comprising a finish polishing step 2 for performing finish polishing of a silicon substrate, and a finish polishing step 1 which is a polishing step prior to the finish polishing step 2, the finish polishing step 1 and the finish polishing step 2 being performed in this order,
The polishing composition used in the finish polishing steps 1 and 2 contains at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B), each having a pKa of 5 or more and 8.5 or less, the pH of the polishing composition is 9 or more and 12 or less, and the difference between the pH and the pKa [pH-pKa] is 2 or more and 6 or less,
In the final polishing step 1, polishing is performed with a polishing composition containing silica particles (component C), and the ratio of the content of component A to the total content of components A and B is 50 mass% or more,
The method for polishing a silicon substrate according to <9>, wherein in the finish polishing step 2, polishing is performed with a polishing composition having a ratio of the content of component B to the total content of components A and B of 50 mass % or more.
<11> The polishing method according to <9> or <10>, wherein component A is at least one selected from the group consisting of a reaction product of polyallylamine and a glycidol derivative and a compound containing a structural unit represented by the above formula (III), and component B is at least one selected from the group consisting of polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyethylacrylamide, and polyethylene glycol having a weight-average molecular weight of 300 or more and 1,000 or less.
<12> The polishing method according to any one of <9> to <11>, wherein the content of component A in the polishing composition is 0 ppm by mass or more and 200 ppm by mass or less, and the content of component B in the polishing composition is 0 ppm by mass or more and 200 ppm by mass or less.
<13> The polishing method according to any one of <9> to <12>, in which Component A has a weight average molecular weight of 800 or more and 12,000 or less, and Component B has a weight average molecular weight of 300 or more and 300,000 or less.
<14> The polishing method according to any one of <9> to <13>, wherein the content of component C in the polishing composition is 0.07 mass % or more and 0.3 mass % or less, and the silicon substrate is a single crystal silicon substrate.
<15> The polishing method according to any one of <9> to <14>, wherein the finish polishing step 1 and the finish polishing step 2 are performed on a single polishing platen.
<16> The polishing method according to any one of <9> to <14>, wherein the finish polishing step 1 and the finish polishing step 2 are performed on different polishing plates.
<17> The polishing method according to any one of <9> to <16>, wherein in the finish polishing step 2, polishing is performed with a polishing liquid composition containing silica particles (component C), and then polishing is performed with a polishing liquid composition not containing silica particles (component C).
<18> A method for producing a semiconductor substrate, comprising carrying out the polishing method according to any one of <1> to <8> or the polishing method according to any one of <9> to <17>.

The present disclosure will be described in further detail below with reference to examples, but these are merely illustrative and the present disclosure is not limited to these examples.

1. Preparation of polishing composition (concentrate of polishing composition)
A concentrate (60 times) of the polishing composition was obtained by mixing and stirring the silica particles (component C), the amino group-containing water-soluble polymer compound (component A), the nonionic water-soluble polymer compound (component B), the ammonia (component D), and ultrapure water shown in Table 1. The pH of the concentrate at 25° C. was 10.3 to 11.0.
(Polishing composition)
The concentrate was diluted 60 times with ion-exchanged water to obtain polishing compositions of Examples 1 to 12 (a1 to a6, b1 to b6) (Table 1). The content of each component in Table 1 is the content of each component (mass % or mass ppm, active content) at the time of use of the diluted polishing composition. The content of ultrapure water is the remainder excluding components A to D. The pH at 25°C of each polishing composition (at the time of use) was 10.1 or 10.3.
The pH at 25° C. was measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and was the value measured one minute after immersing the electrodes of the pH meter in the polishing composition or a concentrate thereof.

The following components A, B, C and D were used in the preparation of each polishing composition.
(Component A)
A1: Methyldiallylamine-sulfur dioxide copolymer [manufactured by Nittobo Medical Co., Ltd., weight average molecular weight 3,000, pKa 7.2]
A2: Glycidol-modified polyallylamine (glycidol modification ratio: 2.0) [manufactured by Nittobo Medical Co., Ltd., weight average molecular weight 11,000, pKa 6.1]
(Component B)
B1: Polyglycerin [Daicel Corporation's "XPW", polymerization degree 40, weight average molecular weight 2,980]
(Component C)
C1: Colloidal silica [average primary particle size 35 nm, average secondary particle size 70 nm, degree of association 2.0]
C2: Colloidal silica [average primary particle size 25 nm, average secondary particle size 49 nm, degree of association 2.0]
(Component D)
Ammonia [28% by weight ammonia water, Kishida Chemical Co., Ltd., special grade reagent]

2. Measurement methods for various parameters (1) Measurement of average primary particle size of silica particles (component C) The average primary particle size (nm) of component C was calculated by the following formula using the specific surface area S ( ^m2 /g) calculated by the BET (nitrogen adsorption) method.
Average primary particle diameter (nm) = 2727/S

The specific surface area S of component C was measured by carrying out the following [pretreatment], and then weighing out about 0.1 g of a measurement sample to four decimal places into a measurement cell, drying the sample for 30 minutes in an atmosphere at 110°C immediately before measuring the specific surface area, and then measuring the specific surface area S by a 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).
[Pretreatment]
(a) The pH of the slurry of component C is adjusted to 2.5±0.1 with an aqueous solution of nitric acid.
(b) Component C in a slurry state 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 ground in an agate mortar.
(d) The ground 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 residue on the filter is washed five times with 20 g of ion-exchanged water (40° C.).
(f) The filter with the filtrate attached thereto is placed in a petri dish and dried in an atmosphere at 110° C. for 4 hours.
(g) The dried filtrate (component C) was taken, being careful not to mix in any filter debris, and finely ground in a mortar to obtain a measurement sample.

(2) Average secondary particle diameter of silica particles (component C) The average secondary particle diameter (nm) of component C was measured by adding an abrasive to ion-exchanged water so that the concentration of component C was 0.25% by mass, and then pouring the resulting aqueous dispersion into a Disposable Sizing Cuvette (a 10 mm polystyrene cell) to a height of 10 mm from the bottom, and using a dynamic light scattering method (apparatus name: "Zetasizer Nano ZS", manufactured by Sysmex Corporation).

(3) Measurement of Weight Average Molecular Weight of Water-Soluble Polymer The weight average molecular weight of the water-soluble polymer (component A, component B) was calculated based on peaks in a chromatogram obtained by applying gel permeation chromatography (GPC) under the following conditions.
<Amino group-containing water-soluble polymer (component A)>
Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated type)
Column: GS-220HQ + GS-620HQ
Eluent: 0.4M NaCl
Flow rate: 1.0mL/min
Column temperature: 30°C
Detector: Shodex RI SE-61 differential refractive index detector Standard material: monodisperse polyethylene glycol with known molecular weight (nonionic water-soluble polymer (component B))
Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated type)
Column: GMPWXL + GMPWXL (anion)
Eluent: 0.2M phosphate buffer/ _CH3CN =9/1
Flow rate: 0.5mL/min
Column temperature: 40°C
Detector: Shodex RI SE-61 differential refractive index detector Standard material: monodisperse polyethylene glycol with known molecular weight

(4) Measurement of pKa Using an HM-41K pH meter (Toa DKK Co., Ltd.), 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.

(5) Glycidol Modification Ratio The glycidol modification ratio was determined by ¹³ C-NMR.
<Measurement conditions>
Sample: 200 mg of glycidol-modified polyallylamine dissolved in 0.6 mL of heavy water. Apparatus used: 400 MHz ¹³ C-NMR (Agilent 400-MR DD2, manufactured by Agilent Technologies, Inc.)
Measurement conditions: ¹³ C-NMR measurement, pulse interval time 5 seconds, tetramethylsilane as standard peak (σ: 0.0 ppm), number of measurement integrations: 5000, range of each peak used for integration:
A: 71.0 to 72.3 ppm (integral value of the peak of C bound to the secondary hydroxyl group of glycidol reacted with an 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 the amount of glycidol to the amount of amino group equivalent) is calculated by the following formula.
Glycidol modification rate (equivalent ratio) = 2A/B

3. Evaluation of polishing compositions (a1 to a6, b1 to b6) (Examples 1 to 12)
(1) Polishing Method, etc. Each polishing composition was filtered with a filter (compact cartridge filter "MCP-LX-C10S", manufactured by Advantec Co., Ltd.) immediately before polishing, and finish polishing and cleaning were performed on the following silicon substrates under the following polishing conditions.
<Silicon substrate to be polished>
Single crystal silicon substrate [silicon single-sided mirror substrate with a diameter of 200 mm, conductivity type: P, crystal orientation: 100, resistivity: 0.1 Ω·cm or more and 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.

<Finish polishing conditions>
Polishing machine: Single-sided 8-inch polishing machine "GRIND-X SPP600s" (manufactured by Okamoto Kogyo)
Polishing pad: Suede pad (manufactured by Toray Coatex Co., Ltd., Asker hardness: 64, thickness: 1.37 mm, nap length: 450 μm, opening diameter: 60 μm)
Silicon substrate polishing pressure: 100 g/ ^cm2
Plate rotation speed: 60 rpm
Polishing time: 5 minutes Supply rate of polishing composition: 150 g/min
Temperature of polishing composition: 23°C
Carrier rotation speed: 62 rpm

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

(2) Evaluation of Polishing Rate The weight of each silicon substrate before and after polishing was measured using a precision balance ("BP-210S" manufactured by Sartorius), and the weight difference obtained was divided by the density, area and polishing time of the silicon substrate to determine the single-sided polishing rate per unit time. The results are shown in Table 1. The weight of the silicon substrate after polishing refers to the weight of the silicon substrate after the above-mentioned finish polishing and cleaning were performed.

(3) Measurement of surface roughness (haze) of silicon substrate The surface roughness of the silicon substrate after the above-mentioned finish polishing and cleaning was measured using a surface roughness measuring device "Surfscan SP1-DLS" (KLA Tencor Corporation) in a dark field wide grazing incidence channel (DWO) (DWO haze). The results are shown in Table 1. The smaller the haze value, the higher the flatness can be evaluated.

As shown in Table 1, the polishing liquid compositions of Examples 1, 2, 5, 7, 8, and 11 were adjusted so that the polishing rate of the silicon substrate took precedence over the surface quality (haze) of the polished substrate by having a composition in which the ratio of the content of component A to the total content of components A and B [A/(A+B)] exceeded 50 mass%. Also, as shown in Table 1, the polishing liquid compositions of Examples 3, 4, 6, 9, 10, and 12 were adjusted so that the ratio of the content of component B to the total content of components A and B [B/(A+B)] exceeded 50 mass% by having a composition in which the ratio of the content of component B to the total content of components A and B [B/(A+B)] exceeded 50 mass%. Thus, the polishing liquid compositions of Examples 3, 4, 6, 9, 10, and 12 were adjusted so that the surface quality (haze) of the polished substrate took precedence over the polishing rate of the silicon substrate.

4. Evaluation of two-stage finish polishing (Examples 2-1, 2-2, Comparative Example 2-1)
(1) Continuous Polishing Finish polishing was performed using the combination of polishing liquid compositions shown in Table 2. After the finish polishing 1, the polishing machine (polishing platen) was changed and the finish polishing 2 was performed continuously without washing and drying. The polishing conditions were the same as those of the above 3.

(2) Evaluation of total polishing amount The weight of each silicon substrate before and after polishing was measured using a precision balance ("BP-210S" manufactured by Sartorius), and the total polishing amount (nm) of the two-stage polishing was calculated by dividing the weight difference obtained by the density and area of the silicon substrate and the polishing time. The results are shown in Table 2. The weight of the silicon substrate after polishing refers to the weight of the silicon substrate after the above-mentioned finish polishing and cleaning were performed.

(3) Measurement of Surface Roughness (Haze) of Silicon Substrate The surface roughness of the silicon substrate after the above-mentioned finish polishing and cleaning was measured in the same manner as described above. The results are shown in Table 2.

As shown in Table 2, in Examples 2-1 and 2-2, the polishing speed of the silicon substrate was prioritized by setting a composition in which the ratio [A/(A+B)] exceeded 50 mass% in the first finishing polish 1, and the surface quality of the substrate after polishing was prioritized by setting a composition in which the ratio [B/(A+B)] exceeded 50 mass% in the final finishing polish 2, thereby achieving both an improvement in the total polishing amount (apparent polishing rate) and an improvement in surface quality.

By using the polishing composition of the present disclosure, it is possible to adjust the polishing rate of the silicon substrate and the surface quality of the silicon substrate after polishing. Therefore, the polishing composition of the present disclosure is useful as a polishing composition used in the manufacturing process of various semiconductor substrates, and is particularly useful as a polishing composition for finish polishing of silicon substrates.

Claims (17)

A method for adjusting the polishing rate of a silicon substrate and the surface quality of the substrate after polishing by using a polishing liquid composition containing at least one component selected from the group consisting of an amino group-containing water-soluble polymeric compound (component A) and a nonionic water-soluble polymeric compound (component B) having a pKa of 5 or more and 8.5 or less, and changing the content ratio of component A to component B. The method of claim 1, wherein the pH of the polishing composition is greater than the pKa of component A. The method according to claim 1 or 2, wherein the difference between the pH of the polishing composition and the pKa of the amino group-containing water-soluble polymeric compound is greater than 0 and less than 7. The method according to any one of claims 1 to 3, wherein component A contains structural units derived from one or more monomers selected from allylamine and diallylamine. The method according to claim 4, wherein at least a portion of the amino groups in the allylamine-derived structural units have a sterically shielding group. The method according to claim 4 or 5, wherein at least a portion of the amino groups in the allylamine-derived structural units are secondary amino groups or tertiary amino groups containing a hydrocarbon group having 3 to 11 carbon atoms and a hydroxyl group. The method according to any one of claims 1 to 6, wherein component A is a reaction product of a polyallylamine and a glycidol derivative. The method according to claim 4, wherein at least a portion of the amino groups in the diallylamine-derived structural units have an electron-withdrawing group at the β- or γ-position. The method according to any one of claims 1 to 4 and 8, wherein component A is a compound containing a constitutional unit represented by the following formula (III):

In formula (III), R ³ is an alkyl group having 1 to 3 carbon atoms which may have a hydroxyl group, and n+m=1. The method according to any one of claims 1 to 9, wherein component B is a water-soluble polymer having an alkylene oxide group, a hydroxyl group, or an amide group in the molecule. The method according to any one of claims 1 to 10, wherein component B is at least one selected from polyglycerin, polyglycerin alkyl ether, polyglycerin alkyl ester, hydroxyalkyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyethylacrylamide, and polyethylene glycol having a weight average molecular weight of 300 or more and 1,000 or less. The method according to any one of claims 1 to 11, wherein the polishing composition further contains silica particles (component C). A method for polishing a silicon substrate, comprising a finish polishing step 2 for performing finish polishing of a silicon substrate, and a finish polishing step 1 which is a polishing step prior to the finish polishing step 2, the finish polishing step 1 and the finish polishing step 2 being performed in this order,
The polishing composition used in the finish polishing steps 1 and 2 contains at least one component selected from the group consisting of an amino group-containing water-soluble polymer compound (component A) and a nonionic water-soluble polymer compound (component B), each having a pKa of 5 or more and 8.5 or less;
In the final polishing step 1, polishing is performed with a polishing composition containing silica particles (component C), and the ratio of the content of component A to the total content of components A and B is 50 mass% or more,
A method for polishing a silicon substrate, wherein in the finish polishing step 2, polishing is performed with a polishing composition having a content of component B of 50 mass % or more relative to the total content of components A and B. The polishing method according to claim 13, wherein the finish polishing step 1 and the finish polishing step 2 are performed on a single polishing platen. The polishing method according to claim 13, wherein the finish polishing step 1 and the finish polishing step 2 are performed on different polishing plates. A polishing method according to any one of claims 13 to 15, wherein in the final polishing step 2, polishing is performed with a polishing composition containing silica particles (component C), and then polishing is performed with a polishing composition not containing silica particles (component C). A method for manufacturing a semiconductor substrate, comprising carrying out a polishing method according to any one of claims 1 to 12 or any one of claims 13 to 16.