Polishing fluid for silicon substrate polishing

Abstract

To provide a polishing fluid for silicon substrate polishing that can improve the polishing rate while reducing the surface roughness (haze) of the substrate after polishing, and furthermore, can suppress corrosion of the silicon substrate during polishing.SOLUTION: A polishing fluid for silicon substrate polishing according to the present disclosure includes the following components A, B, and C, and an aqueous medium. Component A: Silica particles. Component B: An anionic water-soluble polymer comprising structural units b1 derived from styrene and structural units b2 derived from at least one selected from acrylic acid, methacrylic acid, maleic acid, and salts thereof. Component C: A cationic water-soluble polymer having a basic nitrogen-containing group.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] In recent years, the increasing demand for higher storage capacity in semiconductor memories has led to the miniaturization of semiconductor device design rules. As a result, the depth of focus in photolithography used in the semiconductor device manufacturing process has become shallower, and the demand for reduced surface roughness (haze) on silicon substrates (bare wafers) has become increasingly stringent.

[0003] For example, Patent Document 1 discloses a polishing composition for silicon substrates that can achieve an improvement in the removal rate, a reduction in the surface roughness (haze) of the silicon substrate, and storage stability of the concentrate. The polishing composition contains silica particles, an amino group-containing water-soluble polymer having a pKa of 5 or more and 8.5 or less, and a nonionic water-soluble polymer, and has a pH greater than 8.5 and 14 or less. Furthermore, Patent Document 2 proposes an abrasive for polishing a surface containing a silicon oxide film, which comprises abrasive grains, a water-soluble polymer, and water, and the water-soluble polymer is a copolymer of at least one monomer (A) selected from unsaturated dicarboxylic acids, their derivatives, and salts thereof, and a monomer (B) containing an ethylenic double bond but not containing an acidic group. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-63233 [Patent Document 2] International Publication No. 2023 / 145572 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, there has been a growing demand for polishing solutions that can reduce the surface roughness (haze) of the polished substrate, along with improvements in the polishing rate.

[0006] The present disclosure provides a polishing liquid for polishing silicon substrates that can improve the polishing rate while reducing the surface roughness (haze) of the substrate after polishing, and that can also suppress corrosion of the silicon substrate during polishing, as well as 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 slurry for polishing silicon substrates, comprising the following component A, component B, component C, and an aqueous medium: Component A: Silica particles Component B: An anionic water-soluble polymer containing a structural unit b1 derived from styrene and a structural unit b2 derived from at least one selected from acrylic acid, methacrylic acid, maleic acid, and salts thereof. Component C: Cationic water-soluble polymer with basic nitrogen-containing groups

[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 slurry for polishing a silicon substrate of the present disclosure.

[0009] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, including a step of polishing a silicon substrate to be polished using the polishing slurry for polishing silicon substrates of the present disclosure, and a step of cleaning the polished silicon substrate. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a polishing liquid for polishing silicon substrates that can improve the polishing rate while reducing the surface roughness (haze) of the substrate after polishing, and that can also suppress corrosion of the silicon substrate during polishing, as well as a method for polishing a silicon substrate using the polishing liquid for polishing silicon substrates, and a method for manufacturing a semiconductor substrate. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure is based on the findings that by using a polishing liquid for polishing silicon substrates containing silica particles, a specific anionic water-soluble polymer, and a specific cationic water-soluble polymer, silicon substrates can be polished at high speed, the surface roughness (haze) of the substrate after polishing can be reduced, and corrosion of the silicon substrate during polishing can be suppressed.

[0012] That is, in one aspect, the present disclosure relates to a polishing liquid for polishing silicon substrates (hereinafter also referred to as "the polishing liquid of the present disclosure") containing the following component A, component B, component C, and an aqueous medium: Component A: Silica particles Component B: An anionic water-soluble polymer containing a structural unit b1 derived from styrene and a structural unit b2 derived from at least one selected from acrylic acid, methacrylic acid, maleic acid, and salts thereof. Component C: Cationic water-soluble polymer with basic nitrogen-containing groups

[0013] According to one or more embodiments of the present disclosure, it is possible to achieve both an improvement in the polishing rate and a reduction in the surface roughness (haze) of the substrate after polishing, and further to suppress corrosion of the silicon substrate during polishing.

[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. It is generally known that in a polishing liquid containing silica particles and a cationic water-soluble polymer, the cationic water-soluble polymer adsorbs to the silica particles and the silicon substrate, increasing the frequency of contact of the silica particles with the substrate and thereby improving the polishing rate. However, typical cationic water-soluble polymers have a strong adsorption force to silica particles, which tends to cause aggregation of the silica particles and worsen the surface roughness. Therefore, in this disclosure, a water-soluble polymer (component B) containing structural units b1 and b2, which is an anionic polymer having hydrophobic groups, is used in combination with a cationic water-soluble polymer (component C) having basic nitrogen-containing groups. Components B and C form a polymer complex driven by the attractive force based on Coulomb's law. This polymer complex has more electrically neutralized cationic functional groups than component C, improving silica particle dispersibility. Furthermore, the hydrophilic ionic functional groups are electrically neutralized, increasing hydrophobicity. This improves the silicon substrate surface protection effect, inhibiting corrosion of the silicon substrate. This is believed to suppress over-polishing and reduce surface roughness (haze). Furthermore, the formation of the polymer complex enhances the surfactant effect, reducing the surface tension of the polishing liquid and improving the affinity of the polishing liquid to the polishing pad. This improves the retention of the polishing liquid on the polishing pad, potentially improving the polishing rate. 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 of the present disclosure can be used in a polishing step of polishing a silicon substrate to be polished in a semiconductor substrate manufacturing method, or in a polishing step of polishing a silicon substrate to be polished in a silicon substrate polishing method. In one or more embodiments, the silicon substrate to be polished using the polishing liquid of the present disclosure can be a silicon substrate (silicon wafer), etc., and in one or more embodiments, can be a single crystal silicon substrate, a polysilicon substrate, a substrate having a polysilicon film, etc. From the viewpoint of exerting the effects of the polishing liquid of the present disclosure, a single crystal silicon substrate or a polysilicon substrate is preferred, and a single crystal silicon substrate is more preferred.

[0016] [Silica particles (component A)] The polishing liquid 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, with colloidal silica being preferred from the viewpoints of improving the polishing rate and reducing surface roughness (haze). 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 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 known method.

[0018] From the viewpoint of improving the polishing rate, the average primary particle diameter of component A is preferably 10 nm or more, more preferably 20 nm or more, and even more preferably 30 nm or more, and from the viewpoint of reducing surface roughness (haze), it is preferably 50 nm or less, more preferably 45 nm or less, and even more preferably 40 nm or less. More specifically, the average primary particle diameter of component A is preferably 10 nm or more and 50 nm or less, more preferably 20 nm or more and 45 nm or less, and even more preferably 30 nm or more and 40 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 improving the polishing rate, the average secondary particle diameter of component A is preferably 20 nm or more, more preferably 30 nm or more, even more preferably 40 nm or more, and even more preferably 50 nm or more, and from the viewpoint of reducing surface roughness (haze), it is preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less. More specifically, 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 40 nm or more and 80 nm or less, and even more preferably 50 nm or more and 80 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. The average primary particle size and average secondary particle size of component A are the same when measured in the polishing liquid of the present disclosure and in a concentrate of the polishing liquid of the present disclosure described below.

[0020] From the viewpoint of reducing surface roughness (haze), 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, and from the viewpoint of improving the polishing rate, it is preferably 1.1 or more, more preferably 1.5 or more, and even more preferably 1.8 or more. More specifically, the degree of association of component A is preferably 1.1 or more and 3 or less, more preferably 1.5 or more and 2.5 or less, and even more preferably 1.8 or more and 2.3 or less. 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 diameter / average primary particle diameter 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.

[0021] The content of component A in the polishing liquid of the present disclosure is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.03% by mass or more, from the viewpoint of improving the removal rate, and is preferably 3% by mass or less, more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0.2% by mass or less, from the viewpoint of reducing surface roughness (haze). More specifically, the content of component A in the polishing liquid of the present disclosure is preferably 0.01% by mass or more and 3% by mass or less, more preferably 0.02% by mass or more and 1% by mass or less, even more preferably 0.03% by mass or more and 0.5% by mass or less, and even more preferably 0.03% by mass or more and 0.2% by 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.

[0022] [An anionic water-soluble polymer (component B) containing a structural unit b1 derived from styrene and a structural unit b2 derived from at least one acid selected from acrylic acid, methacrylic acid, maleic acid, and salts thereof] In one or more embodiments, the polishing liquid of the present disclosure contains an anionic water-soluble polymer (hereinafter also referred to as "component B") that includes a structural unit b1 (hereinafter also simply referred to as "structural unit b1") derived from styrene (St) and a structural unit b2 (hereinafter also simply referred to as "structural unit b2") derived from at least one selected from acrylic acid (AA), methacrylic acid (MAA), maleic acid (MA), and salts thereof, from the viewpoints of improving the removal rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate. Examples of the salt include alkali metal salts, alkaline earth metal salts, ammonium salts, and organic ammonium salts. The structural unit b1 may be of one type or a combination of two or more types. The structural unit b2 may be of one type or a combination of two or more types. The component B may be of one type or a combination of two or more types. In the present disclosure, Component B being "water-soluble" means that it has a solubility in water (20°C) of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more.

[0023] The content (mol %) of the structural unit b1 in all structural units of Component B is preferably 20 mol % or more, more preferably 30 mol % or more, even more preferably 51 mol % or more, and even more preferably 60 mol % or more, from the viewpoint of simultaneously improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, and from the same viewpoint, is preferably 90 mol % or less, more preferably 80 mol % or less, and even more preferably 70 mol % or less. More specifically, the content of the structural unit b1 in all structural units of Component B is preferably 20 mol % or more and 90 mol % or less, more preferably 30 mol % or more and 80 mol % or less, even more preferably 51 mol % or more and 70 mol % or less. The content (mol %) of the structural unit b2 in all structural units of Component B is preferably 10 mol % or more, more preferably 20 mol % or more, and even more preferably 30 mol % or more, from the viewpoint of simultaneously improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, and from the same viewpoint, is preferably 80 mol % or less, more preferably 70 mol % or less, even more preferably 49 mol % or less, and even more preferably 40 mol % or less. More specifically, the content of the structural unit b2 in all structural units of Component B is preferably 10 mol % or more and 80 mol % or less, more preferably 20 mol % or more and 70 mol % or less, even more preferably 30 mol % or more and 49 mol % or less, and even more preferably 30 mol % or more and 40 mol % or less.

[0024] Component B may further contain other structural units in addition to structural units b1 and b2. Preferred examples of such other structural units include (meth)acrylic acid esters, N-alkyl(meth)acrylamides, N,N-dialkyl(meth)acrylamides, vinyl phosphoric acid, styrenesulfonic acid, and 2-acrylamido-2-methylpropanesulfonic acid. In the present disclosure, "(meth)acrylic" refers to one or more structures selected from acrylic and methacrylic. In the present disclosure, the content of structural units b1 and b2 relative to all structural units constituting component B [(moles of structural unit b1 + moles of structural unit b2) / (total moles of all structural units constituting component B)] is preferably 60 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, and even more preferably substantially 100 mol%. In the present disclosure, the content of structural units b1 and b2 relative to all structural units constituting component B is substantially 100 mol%. This means that all structural units constituting component B are composed of structural units b1 and b2, but that the presence of compounds other than structural units b1 and b2 that can become structural units of component B, present as impurities in structural units b1 and b2, is permitted. In the present disclosure, preferred examples of component B include at least one selected from styrene / acrylic acid copolymer (St / AA), styrene / methacrylic acid copolymer (St / MAA), and styrene / maleic acid copolymer (St / MA), and among these, styrene / maleic acid copolymer (St / MA) is more preferred.

[0025] Component B can be obtained by a known method, such as solution polymerization of a monomer mixture containing styrene and at least one selected from acrylic acid, methacrylic acid, maleic acid, and salts thereof. Examples of solvents used in solution polymerization include water; aromatic hydrocarbons such as toluene and xylene; alcohols such as ethanol and 2-propanol; ketones such as acetone and methyl ethyl ketone; and ethers such as tetrahydrofuran and diethylene glycol dimethyl ether. Examples of polymerization initiators used in polymerization include known radical initiators, such as ammonium persulfate salts. A chain transfer agent can also be used during polymerization, such as thiol-based chain transfer agents such as 2-mercaptoethanol and β-mercaptopropionic acid. In the present disclosure, the content of each structural unit in all structural units of Component B can be considered as the ratio of each monomer to the total amount of monomers used in polymerization.

[0026] The arrangement of the structural units constituting component B may be random, alternating, block, or graft, or a combination of these.

[0027] From the viewpoint of simultaneously improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, the weight-average molecular weight of Component B is preferably 1,500 or more, more preferably 2,000 or more, even more preferably 3,000 or more, even more preferably 5,000 or more, and even more preferably 6,000 or more, and from the same viewpoint, it is preferably 100,000 or less, more preferably 50,000 or less, even more preferably 30,000 or less, and even more preferably 10,000 or less. More specifically, the weight-average molecular weight of Component B is preferably 1,500 or more and 100,000 or less, more preferably 2,000 or more and 50,000 or less, even more preferably 3,000 or more and 30,000 or less, even more preferably 5,000 or more and 10,000 or less, and even more preferably 6,000 or more and 10,000 or less. In the present disclosure, the weight average molecular weight is a value measured using gel permeation chromatography (GPC) under the conditions described in the Examples.

[0028] From the viewpoints of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate, the content of component B in the polishing liquid of the present disclosure is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, even more preferably 0.0025% by mass or more, even more preferably 0.003% by mass or more, still more preferably 0.004% by mass or more, and even more preferably 0.005% by mass or more; and from the viewpoint of improving the polishing rate, the content is preferably 0.1% by mass or less, more preferably 0.05% by mass or less, even more preferably 0.02% by mass or less, still more preferably 0.01% by mass or less, and even more preferably 0.0075% by mass or less. More specifically, the content of Component B is preferably 0.001% by mass or more and 0.1% by mass or less, more preferably 0.0025% by mass or more and 0.05% by mass or less, even more preferably 0.003% by mass or more and 0.02% by mass or less, even more preferably 0.004% by mass or more and 0.01% by mass or less, and even more preferably 0.005% by mass or more and 0.0075% 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.

[0029] The mass ratio B / A of component B to component A (content of component B / content of component A) in the polishing liquid of the present disclosure is preferably 0.01 or more, more preferably 0.05 or more, even more preferably 0.1 or more, and even more preferably 0.15 or more, from the viewpoint of simultaneously achieving an improvement in the polishing rate, a reduction in surface roughness (haze), and inhibition of corrosion of the silicon substrate, and from the same viewpoint, is preferably 1 or less, more preferably 0.75 or less, even more preferably 0.4 or less, and even more preferably 0.3 or less. More specifically, the mass ratio B / A in the polishing liquid of the present disclosure is preferably 0.01 or more and 1 or less, more preferably 0.05 or more and 0.4 or less, even more preferably 0.1 or more and 0.75 or less, even more preferably 0.15 or more and 0.4 or less, and even more preferably 0.15 or more and 0.3 or less.

[0030] [Cationic water-soluble polymer having a basic nitrogen-containing group (component C)] The polishing liquid of the present disclosure contains a cationic water-soluble polymer having a basic nitrogen-containing group (hereinafter also referred to as "Component C"). The basic nitrogen-containing group may be at least one selected from an amino group, a quaternary ammonium group, a nitrogen-containing aromatic ring group, and salts thereof. Examples of the salt include hydrobromide, acetate, sulfate, nitrate, sulfite, phosphate, amidosulfate, methanesulfonate, and ethanesulfonate. In the present disclosure, Component C being "water-soluble" means that it has a solubility in water (20°C) of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more.

[0031] From the viewpoints of improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, Component C preferably contains a structural unit derived from one or more selected from allylamine and diallylamine. From the viewpoint of availability, Component C, in one or more embodiments, more preferably contains a structural unit derived from allylamine.

[0032] (Structural unit derived from allylamine) When component C includes an allylamine-derived structural unit, in one or more embodiments, at least one nitrogen atom of the amino group in the allylamine-derived structural unit preferably has a steric shielding group from the viewpoints of improving the polishing rate, reducing surface roughness (haze), inhibiting corrosion of the silicon substrate, and from the viewpoint of availability. In the present disclosure, the steric shielding group refers to a steric (bulky) substituent that can shield the nitrogen atom of the amino group in the allylamine-derived structural unit and inhibit cationization, i.e., lowering the pKa. From the same viewpoint, the steric shielding group is preferably a hydrocarbon group having 3 to 11 carbon atoms and a hydroxyl group. The number of carbon atoms in the hydrocarbon group is preferably 3 or more from the viewpoints of improving the shielding of the nitrogen atom of the amino group (inhibiting cationization of the nitrogen atom of the amino group) and achieving both an improved polishing rate and a reduced surface roughness (haze). From the viewpoints of improving water solubility and availability, the number of carbon atoms is preferably 11 or less, more preferably 7 or less, even more preferably 5 or less, and even more preferably 4 or less.

[0033] When Component C contains a structural unit derived from allylamine, in one or more embodiments, from the viewpoint of simultaneously achieving an improvement in the polishing rate, a reduction in surface roughness (haze), and inhibition of corrosion of the silicon substrate, the structural unit derived from allylamine preferably contains a structural unit having an oxygen atom at one or more positions selected from the β-position, γ-position, and δ-position of the nitrogen atom of the amino group contained in the structural unit derived from allylamine.

[0034] In the present disclosure, when component C contains a structural unit derived from allylamine, in one or more embodiments, the structural unit having an oxygen atom at one or more positions selected from the β-position, γ-position, and δ-position of the nitrogen atom of the amino group in the structural unit derived from allylamine more preferably has a structure derived from a glycidol derivative. In the present disclosure, the structure derived from a glycidol derivative is "-(CH2-CHOH-CH2OR)-(C1H-CH2 ... 0 ) structure, where R 0means a hydrogen atom or a hydrocarbon having 1 to 8 carbon atoms which may have a branch. In the present disclosure, when Component C includes a structural unit derived from allylamine, the equivalent of the glycidol derivative relative to the number of amino groups in the structural unit derived from allylamine (1 equivalent) (hereinafter also referred to as "glycidol modification rate") is, from the viewpoint of reducing surface roughness (haze), preferably 0.3 or more, more preferably 0.5 or more, even more preferably 0.8 or more, still more preferably 1 or more, even more preferably more than 1.1, still more preferably 1.2 or more, still more preferably 1.3 or more, and still more preferably 1.4 or more; and, from the viewpoint of improving the polishing rate, it is preferably 4 or less, more preferably 3 or less, still more preferably 2.5 or less, still more preferably 2 or less, still more preferably 1.9 or less, and still more preferably 1.6 or less. More specifically, in the present disclosure, the glycidol modification rate is preferably 0.3 or more and 4 or less, more preferably 0.5 or more and 3 or less, even more preferably 0.8 or more and 2.5 or less, still more preferably 1 or more and 2 or less, still more preferably more than 1.1 and 1.9 or less, still more preferably 1.2 or more and 1.6 or less, still more preferably 1.3 or more and 1.6 or less, and still more preferably 1.4 or more and 1.6 or less.

[0035] In the present disclosure, the glycidol modification rate is 13 It is preferable to use a value measured by the method described in the Examples using C-NMR, but 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.

[0036] Examples of the glycidol derivative include glycidol and alkyl glycidyl ether, with glycidol being preferred from the viewpoints of availability and improving the polishing rate. From the viewpoint of availability, the alkyl group of the alkyl glycidyl ether is preferably an alkyl group having 1 to 8 carbon atoms, which may be branched, 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.

[0037] In one or more embodiments, the constituent unit derived from allylamine is preferably a polyallylamine in which at least some of the amino groups in the constituent unit derived from allylamine have a steric shielding group, more preferably a polyallylamine in which at least some of the amino groups in the constituent unit derived from allylamine have a structure derived from a glycidol derivative, and even more preferably a polyallylamine in which at least some of the amino groups in the constituent unit derived from allylamine have a structure derived from glycidol.

[0038] When Component C contains a structural unit derived from allylamine, in one or more embodiments, Component C is preferably one containing a structural unit of the following formula (I) (glycidol derivative-modified polyallylamine): [ka]

[0039] In formula (I), R 1 and R 2 are each independently a hydrogen atom or a 1-mol or 2-mol adduct of a glycidol derivative, provided that R 1 and R 2 They cannot simultaneously become hydrogen atoms. That is, in the present disclosure, component C includes a structural unit derived from allylamine, and at least one hydrogen atom of the amino group in the structural unit derived from allylamine is exchanged with a hydroxy group formed by ring-opening of an epoxy group of a glycidol derivative, "-(CH2-CHOH-CH2OR 0 It is more preferable that the cationic water-soluble polymer is an amino group substituted with a group having the structure "R 0 means a hydrogen atom or an optionally branched hydrocarbon having 1 to 8 carbon atoms. In one or more embodiments, component C is more preferably a cationic water-soluble polymer that contains a structural unit derived from allylamine, in which the amino group in the structural unit derived from allylamine is an amino group in which at least one hydrogen atom of the amino group has been substituted with one or more amino groups selected from -CHCH(OH)CH(OH) and -CHCH(OH)CHO-CHCH(OH)CH(OH), more preferably -CHCH(OH)CH(OH).

[0040] (Structural unit derived from diallylamine) When Component C contains a constitutional unit derived from diallylamine, in one or more embodiments, at least a portion of the amino groups in the constitutional unit derived from diallylamine preferably have an electron-withdrawing group at the β- or γ-position of the amino group, from the viewpoint of simultaneously improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate. Examples of the electron-withdrawing group include a group represented by the following formula (II):

[0041] [ka]

[0042] When Component C contains a constituent unit derived from diallylamine, in one or more embodiments, Component C is a compound containing a constituent unit derived from diallylamine and a constituent unit derived from sulfur dioxide, and preferred examples include compounds containing a constituent unit of the following formula (III): [ka]

[0043] 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.

[0044] That is, in one or more embodiments of the present disclosure, Component C is preferably a compound containing a structural unit represented by the following formula (IV), and more specifically, a methyldiallylamine / sulfur dioxide copolymer is more preferably mentioned. [ka]

[0045] From the viewpoint of improving the polishing rate, Component C has a weight average molecular weight of preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and still more preferably 2,000 or more. From the viewpoint of improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, 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 still more preferably 12,000 or less. The weight average molecular weight of Component C in the present disclosure can be measured, for example, by the method described in the Examples. When Component C contains a structural unit derived from allylamine, the weight-average molecular weight of Component C is, from the viewpoint of improving the polishing rate, preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, still more preferably 2,000 or more, preferably 3,000 or more, more preferably 5,000 or more, even more preferably 6,000 or more, and still more preferably 7,000 or more; and from the viewpoints of improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, 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, and still more preferably 10,000 or less. When Component C contains a constitutional unit derived from diallylamine, the weight-average molecular weight of Component C is preferably 800 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and still more preferably 2,000 or more, from the viewpoint of improving the polishing rate, reducing surface roughness (haze), and inhibiting corrosion of the silicon substrate, 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.

[0046] The content of component C in the polishing liquid of the present disclosure is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, and even more preferably 0.003% by mass or more, from the viewpoint of improving the polishing rate. From the viewpoint of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate, it is preferably 0.1% by mass or less, more preferably 0.03% by mass or less, and even more preferably 0.02% by mass or less. More specifically, the content of component C in the polishing liquid of the present disclosure is preferably 0.001% by mass or more and 0.1% by mass or less, more preferably 0.002% by mass or more and 0.02% by mass or less, and even more preferably 0.003% by mass or more and 0.02% by mass or less. When component C is a combination of two or more types, the content of component C is the total content thereof. From the viewpoint of simultaneously achieving an improvement in the removal rate, a reduction in surface roughness (haze), and inhibition of corrosion of the silicon substrate, the total content of the allylamine-derived structural units and the diallylamine-derived structural units in component C in the polishing liquid of the present disclosure is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably substantially 100% by mass. In the present disclosure, the total content of the allylamine-derived structural units and the diallylamine-derived structural units in component C being substantially 100% by mass means that component C is composed of allylamine-derived structural units and diallylamine-derived structural units, but that the presence of other components that are present as impurities in the allylamine-derived structural units and diallylamine-derived structural units and that can become structural units of component C is permitted. Furthermore, from the same viewpoint as above, the content of allylamine-derived structural units in component C in the polishing liquid of the present disclosure is preferably 60% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and even more preferably substantially 100% by mass. In the present disclosure, the content of allylamine-derived structural units in component C being substantially 100% by mass means that component C is composed of allylamine-derived structural units, but allows for the presence of compounds other than the allylamine-derived structural units that are present as impurities in the allylamine-derived structural units and that can become structural units of component C.

[0047] The mass ratio C / A of component C to component A (content of component C / content of component A) in the polishing liquid of the present disclosure is preferably 0.01 or more, more preferably 0.1 or more, and even more preferably 0.2 or more, from the viewpoint of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate, and is preferably 10 or less, more preferably 5 or less, and even more preferably 1 or less, from the viewpoint of improving the polishing rate.

[0048] The mass ratio C / B of component C to component B (content of component C / content of component B) in the polishing liquid of the present disclosure is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 0.8 or more from the viewpoint of improving the polishing rate, and is preferably 8 or less, more preferably 5 or less, and even more preferably 2 or less from the viewpoint of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate. More specifically, the mass ratio C / B in the polishing liquid of the present disclosure is preferably 0.3 or more and 8 or less, more preferably 0.5 or more and 5 or less, and preferably 0.8 or more and 2 or less.

[0049] [Aqueous medium] Examples of the aqueous medium contained in the polishing liquid of the present disclosure include water such as distilled water, ion-exchanged water, pure water, and ultrapure water, or a mixed solvent of water and a solvent. Examples of the solvent include a solvent miscible with water (e.g., alcohol such as ethanol). When the aqueous medium is a mixed solvent of water and a solvent, the proportion of water in the entire mixed medium is not particularly limited as long as the effects of the present disclosure are not impaired. From an economical viewpoint, for example, 95% by mass or more is preferable, and 98% by mass or more is more preferable. From the viewpoint of surface cleanliness of the substrate to be polished, the aqueous medium is preferably water, more preferably ion-exchanged water and ultrapure water, and even more preferably ultrapure water. The content of the aqueous medium in the polishing liquid of the present disclosure can be the remainder excluding Component A, Component B, Component C, and any optional components described below that are blended as necessary.

[0050] [Nitrogen-containing basic compound (component D)] In one or more embodiments, the polishing liquid of the present disclosure may further contain 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 improving the polishing rate and reducing surface roughness (haze). In the present disclosure, "water-soluble nitrogen-containing basic compound" refers to a nitrogen-containing compound that exhibits basicity when dissolved in water. In the present disclosure, component D does not include component C. Component D may be one type or a combination of two or more types. In the present disclosure, Component D being "water-soluble" means that it has a solubility in water (20°C) of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more.

[0051] 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 simultaneously improving the polishing rate, reducing the surface roughness (haze), and inhibiting corrosion of the silicon substrate, ammonia or a mixture of ammonia and hydroxyamine is preferred as component D, and ammonia is more preferred.

[0052] When the polishing liquid of the present disclosure contains component D, the content of component D in the polishing liquid of the present disclosure is preferably 0.0005% by mass or more, more preferably 0.001% by mass or more, and even more preferably 0.002% by mass or more, from the viewpoint of improving the polishing rate; and from the viewpoint of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate, it is preferably 0.05% by mass or less, more preferably 0.03% by mass or less, and even more preferably 0.01% by mass or less. More specifically, the content of component D in the polishing liquid of the present disclosure is preferably 0.0005% by mass or more and 0.05% by mass or less, more preferably 0.001% by mass or more and 0.03% by mass or less, and even more preferably 0.002% by mass or more and 0.01% by mass or less. When component D is a combination of two or more types, the content of component D refers to the total content thereof.

[0053] [Other ingredients] The polishing liquid 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.

[0054] In one or more embodiments, the polishing liquid of the present disclosure may be one that does not contain cerium oxide particles. For example, the content of cerium oxide particles in the polishing liquid of the present disclosure is preferably less than 0.05% by mass, more preferably 0.01% by mass or less, and even more preferably 0% by mass (i.e., no cerium oxide particles are contained).

[0055] [pH] From the viewpoint of improving the removal rate, the pH of the polishing liquid of the present disclosure is preferably greater than 8.5, more preferably greater than 9, even more preferably greater than 9.5, and even more preferably greater than 10, and from the viewpoint of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate, it is preferably less than 14, more preferably less than 13, even 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. More specifically, the pH of the polishing liquid of the present disclosure is preferably greater than 8.5 and less than 14, more preferably less than 9, more preferably less than 13, even 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, more preferably less than 11.5, even more preferably less than 10, more preferably less than 11. The pH of the polishing liquid of the present disclosure can be adjusted using component D or a known pH adjuster. In the present disclosure, the pH is a value measured by the method described in the Examples.

[0056] [Zeta potential] In one or more embodiments, the zeta potential of the polishing liquid of the present disclosure is preferably −10 mV or less, more preferably −15 mV or less, and even more preferably −20 mV or less, from the viewpoint of reducing surface roughness (haze) and inhibiting corrosion of the silicon substrate, and is preferably −35 mV or more, more preferably −30 mV or more, and even more preferably −25 mV or more, from the viewpoint of improving the polishing rate. More specifically, the zeta potential of the polishing liquid of the present disclosure is preferably −35 mV or more to −5 mV or less, more preferably −30 mV or more to −10 mV or less, and even more preferably −25 mV or more to −15 mV or less. The zeta potential of the polishing liquid of the present disclosure can be measured by the method described in the Examples.

[0057] The polishing liquid of the present disclosure can be produced, for example, by blending component A, component B, component C, an aqueous medium, and, if necessary, optional components (component D, other components) using a known method. That is, the polishing liquid of the present disclosure can be produced, for example, by blending at least component A, component B, component C, and an aqueous medium. Therefore, in another aspect, the present disclosure relates to a method for producing a polishing liquid, comprising blending at least component A, component B, component C, and an aqueous medium. In the present disclosure, "blending" includes mixing component A, component B, component C, the aqueous medium, and, if necessary, optional components (component D, 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 blending amounts of each component in the above-described method for producing a polishing liquid of the present disclosure can be the same as the preferred contents of each component in the polishing liquid of the present disclosure.

[0058] In the present disclosure, the "content of each component in the polishing liquid" refers to the content of each component at the time when the polishing liquid is first used for polishing. Hereinafter, the polishing liquid used for polishing is also referred to as the "polishing liquid at the time of use."

[0059] The polishing liquid of the present disclosure may be produced as a concentrate from the viewpoint of storage and transportation, and may include a form that is diluted upon use. That is, in one or more embodiments, the present disclosure relates to a concentrate for obtaining the polishing liquid of the present disclosure. The concentration ratio of the polishing liquid concentrate of the present disclosure 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 200 times or less, and even more preferably 150 times or less, from the viewpoint of storage stability. The concentration ratio of the polishing liquid concentrate of the present disclosure means [solids concentration of the polishing liquid concentrate / solids concentration of the polishing liquid at the time of use]. Here, "solids concentration of the polishing liquid concentrate" refers to the ratio of the mass of components other than water in the polishing liquid concentrate to the mass of the polishing liquid concentrate, and "solids concentration of the polishing liquid at the time of use" refers to the ratio of the mass of components other than water in the polishing liquid at the time of use to the mass of the polishing liquid at the time of use. The polishing liquid concentrate of the present disclosure can be diluted with water so that the content of each component at the time of use is the content described above (i.e., the content of each component in the polishing liquid at the time of use).

[0060] [Polishing liquid kit] In another aspect, the present disclosure relates to a polishing liquid kit for producing the polishing liquid of the present disclosure (hereinafter also referred to as the "kit of the present disclosure"). The kit of the present disclosure provides a polishing liquid for polishing silicon substrates that can achieve both an improved polishing rate and a reduced surface roughness (haze) and that can also suppress corrosion of the silicon substrate during polishing. In one or more embodiments, the kit of the present disclosure includes a polishing liquid kit containing a solution containing components A, B, and C. The solution may contain the optional components described above (component D and other components) as needed, or the polishing liquid of the present disclosure may be produced by mixing the kit of the present disclosure that does not contain the optional components with an aqueous medium that may contain the optional components. The aqueous medium that may contain the optional components and that is to be mixed with the kit of the present disclosure means a liquid medium that contains water in a maximum proportion by mass.

[0061] [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 of the present disclosure (hereinafter also referred to as the "polishing step"). The polishing method of the present disclosure uses the polishing liquid of the present disclosure, which makes it possible to achieve both an improved polishing rate and a reduced surface roughness (haze), and further to suppress corrosion of the silicon substrate during polishing.

[0062] In the polishing step of the polishing method of the present disclosure, for example, a silicon substrate to be polished is pressed against a surface plate to which a polishing pad is attached, and a pressure of, for example, 3 g / cm 2 More than 200g weight / cm 2 The silicon substrate can be polished at the following polishing pressure: 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.

[0063] In the polishing step of the polishing method of the present disclosure, for example, it is preferable to press the silicon substrate to be polished against a platen to which a polishing pad is attached, and polish the silicon substrate to be polished with the polishing liquid of the present disclosure and a polishing pad surface temperature of 15° C. to 40° C. From the viewpoint of simultaneously achieving an improved polishing rate and a reduced surface roughness (haze), the temperature of the polishing liquid of the present disclosure and the surface temperature of the polishing pad are preferably 15° C. or higher, more preferably 20° C. or higher, and preferably 40° C. or lower, and more preferably 30° C. or lower.

[0064] [Method of manufacturing semiconductor substrate] In one 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 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 of the present disclosure, it is possible to achieve both an improvement in the polishing rate and a reduction in surface roughness (haze), and further to suppress corrosion of the silicon substrate during polishing, thereby enabling high-quality semiconductor substrates to be manufactured at high yield, high productivity, and low cost.

[0065] 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, 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. The polishing liquid of the present disclosure is more preferably used in the finish polishing step from the viewpoint of achieving both an improvement in the polishing rate and a reduction in surface roughness (haze).

[0066] 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 an improvement in the polishing rate and a reduction in surface roughness (haze), the polishing liquid of the present disclosure is more preferably used in the step of removing irregularities in the polysilicon film to planarize the substrate.

[0067] The polishing step in the semiconductor substrate manufacturing method of the present disclosure can be performed under the same conditions (polishing pressure, surface temperature of the polishing liquid and polishing pad of the present disclosure, etc.) as the polishing step in the polishing method of the present disclosure described above.

[0068] In one or more embodiments, the semiconductor substrate manufacturing method of the present disclosure may include a dilution step of diluting the concentrated polishing liquid of the present disclosure before the polishing step. The diluent can be, for example, water.

[0069] In the semiconductor substrate manufacturing method of the present disclosure, it is preferable to have a cleaning step after the polishing step. In order to reduce residues on the silicon substrate surface, the cleaning step preferably involves inorganic cleaning. In the present disclosure, inorganic cleaning refers to a step of cleaning the silicon substrate with a cleaning agent (inorganic cleaning agent) containing at least one component selected from hydrogen peroxide, ammonia, hydrochloric acid, sulfuric acid, hydrofluoric acid, and ozone-containing water.

[0070] 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]

[0071] 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.

[0072] 1. Preparation of Concentrated Polishing Liquid for Silicon Substrate Polishing (Examples 1 to 15, Comparative Example 1) Each component shown in Table 1 and ultrapure water were mixed with stirring to obtain concentrates (concentration rate 100 times) of the polishing slurry for polishing silicon substrates of Examples 1 to 15 and Comparative Example 1. The content of each component shown in Table 1 is the content (mass %, active content) of each component in the concentrate of the polishing liquid for polishing silicon substrates. The content of water in the concentrate of the polishing liquid for polishing silicon substrates is the remainder excluding component A and component B or non-component B and component C. The pH of each concentrate of the polishing liquid for polishing silicon substrates at 25°C was 10.6 to 11.0.

[0073] 2. Preparation of polishing liquid for silicon substrate polishing (at the time of use) (Examples 21 to 35, Comparative Example 21) A concentrated polishing slurry for polishing silicon substrates shown in Table 1, ammonia (component D), and ion-exchanged water were mixed to obtain polishing slurry for polishing silicon substrates of Examples 21 to 35 and Comparative Example 21 shown in Table 2. The content of each component shown in Table 2 is the content of each component (mass%, active content) when the polishing liquid for polishing silicon substrates is used. The content of water when the polishing liquid for polishing silicon substrates is the remainder excluding component A and component B or non-component B, component C, and component D. The pH of each polishing liquid for polishing silicon substrates (when used) at 25°C was 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 pH meter electrode in the polishing liquid or its concentrate.

[0074] The following components A, B, non-component B, C, and D were used to prepare the above-mentioned concentrate of polishing liquid for polishing silicon substrates and the polishing liquid for polishing silicon substrates. (Component A) Colloidal silica [average primary particle size 35 nm, average secondary particle size 70 nm, degree of association 2.0] (Component B) B-1: St / MA [styrene / maleic acid copolymer ammonium, manufactured by Polyscope, weight average molecular weight 5,000, styrene:maleic acid = 1:1 (molar ratio)] B-2: St / MA [styrene-maleic acid copolymer ammonium, manufactured by Polyscope, weight average molecular weight 6,500, styrene:maleic acid = 2:1 (molar ratio)] B-3: St / MA [styrene-maleic acid copolymer ammonium, manufactured by Polyscope, weight average molecular weight 10,000, styrene:maleic acid = 3:1 (molar ratio)] (Non-ingredient B) B-4: PAA [Polyammonium acrylate, manufactured by Kao Corporation, weight-average molecular weight 38,000] (Component C) PAA / Gly [glycidol-modified polyallylamine, glycidol modification ratio 1.5, manufactured by Nittobo Medical Co., Ltd., weight-average molecular weight 26,000] (Component D) Ammonia [28% by mass ammonia water, Kishida Chemical Co., Ltd., special grade reagent]

[0075] 3.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 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 measurement 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 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 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.

[0076] (2) Average secondary particle size of silica particles (component A) The average secondary particle diameter (nm) of component A was determined by adding component A to ion-exchange water so that the concentration of component A 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. The particle size distribution measured using a dynamic light scattering method (apparatus name: Zetasizer Nano ZS, manufactured by Sysmex Corporation) was determined to be the particle size (D50) at which the cumulative volume fraction was 50%, and this was taken as the average secondary particle diameter of the silica particles (component A).

[0077] (3) Measurement of the weight-average molecular weight of water-soluble polymers The weight average molecular weights of the water-soluble polymers (component B, non-component B, and component C) were calculated based on peaks in a chromatogram obtained by applying gel permeation chromatography (GPC) under the following conditions. <Anionic Water-Soluble Polymer (Component B or Non-Component B) Having a Structural Unit b1 Derived from Styrene and a Structural Unit b2 Derived from at Least One Selected from Acrylic Acid, Methacrylic Acid, Maleic Acid, and Salts Thereof> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: G4000SWXL + G2000SWXL (Tosoh) Eluent: 30mM CH3COONa aqueous solution / CH3CN=6 / 4(v / v) Flow rate: 0.7ml / min Column temperature: 40℃ Detector: UV 280 nm Standard material: Nishio Kogyo Co., Ltd., sodium polystyrene sulfonate (monodisperse sodium polystyrene sulfonate: molecular weight: 206, 1,800, 4,000, 8,000, 18,000, 35,000, 88,000, 780,000) <Cationic water-soluble polymer with basic nitrogen-containing groups (component C)> Apparatus: HLC-8320 GPC (Tosoh Corporation, detector integrated) Column: α-M + α-M Eluent: Eluent adjusted to 0.15 mol of Na2SO4 in 1 L of water and 10.1 g of CH3COOH in 1000 g of water Flow rate: 1.0mL / min Column temperature: 40℃ Detector: Shodex RI SE-61 differential refractive index detector Standard: Monodisperse polyethylene glycol with known molecular weight

[0078] (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, inverse gate decoupling method, pulse interval time 30 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

[0079] 4. Evaluation of the polishing liquids (when used) for polishing silicon substrates in Examples 21 to 35 and Comparative Example 21 (1) Measurement of the zeta potential of polishing solutions for silicon substrate polishing Each of the polishing solutions for polishing silicon substrates in Examples 21 to 35 and Comparative Example 21 was placed in a disposable zeta potential cell DTS1070 (manufactured by Malvern), and the zeta potential was measured under the following conditions using a Zetasizer Nano ZS (manufactured by Malvern). <Measurement conditions> Sample: Refractive index: 1.450, Absorption coefficient: 0.010 Dispersion medium: Viscosity: 0.8872 cP, Refractive index: 1.330, Dielectric constant: 78.5 Measurement temperature: 25℃

[0080] (2) Polishing method etc. The polishing solutions for polishing silicon substrates of Examples 21 to 35 and Comparative Example 21 were each 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 solution for primary polishing. The haze of the single crystal silicon substrate after rough polishing and subjected to finish polishing was 2 to 3 ppm. <Finishing polishing conditions> Polishing machine: Single-sided 8-inch polishing machine "GRIND-X SPP600s" (manufactured by Okamoto Kogyo) Polishing pad: Suede pad (manufactured by Toray Cortex, Asker hardness: 64, thickness: 1.37 mm, nap length: 450 μm, opening diameter: 60 μm) Silicon substrate polishing pressure: 100 g / cm 2 Plate rotation speed: 60 rpm Polishing time: 5 minutes Supply rate of polishing liquid for silicon substrate polishing: 150 g / min Temperature of polishing solution for silicon substrate polishing: 23℃ 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. For ozone cleaning, an aqueous solution containing 20 ppm ozone was sprayed from a nozzle toward the center of a silicon substrate rotating at 600 rpm at a flow rate of 1 L / min for 3 minutes. The temperature of the ozone water was kept at room temperature. Next, dilute hydrofluoric acid cleaning was performed. In 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. The above ozone cleaning and dilute hydrofluoric acid cleaning were performed twice, and then spin drying was performed by rotating the silicon substrate at 1,500 rpm.

[0081] (3) Evaluation of polishing speed The mass of each silicon substrate before and after polishing was measured using a precision balance (Sartorius BP-210S), and the resulting mass difference was divided by the density, area, and polishing time of the silicon substrate to determine the single-side polishing rate per minute (unit: nm / min). The results are shown in Table 2. The mass of the silicon substrate after polishing is the mass of the silicon substrate after the above-mentioned finish polishing and cleaning have been performed.

[0082] (4) Evaluation of corrosion amount An 8-inch (100) single-crystal silicon wafer was cut into 4 x 4 cm pieces using a diamond cutter to prepare test specimens. The mass (g) of the test specimen was measured to four decimal places using the precision balance. The test specimen was then immersed in acetone for 1 minute so that the entire surface was immersed, then rinsed with ultrapure water, then immersed in 1% ammonium hydrofluoride diluted with ultrapure water for 1 minute so that the entire surface was immersed, then rinsed with ultrapure water, and finally dried with an air blower. 100 g of the polishing liquid for polishing silicon substrates of Examples 21 to 35 and Comparative Example 21 listed in Table 2 was weighed into a disposable cup, and the test piece was immersed so that the entire surface was immersed. The cup was then left to stand in a thermostatic bath (ESPEC Corporation, model: PU-4J) set to 60°C for 24 hours to allow corrosion to occur. Next, the test piece was taken out of the thermostatic chamber, rinsed over its entire surface with ultrapure water, and dried with an air blower. The mass (g) of the test piece was then measured to four decimal places using the precision balance. The weight of the test piece after immersion was subtracted from the weight of the test piece before immersion, and the difference was taken as the amount of corrosion per 24 hours (unit: mg / 24h).

[0083] (5) Measurement of surface roughness (haze) of silicon substrates The values ​​(DWO haze units: ppm) measured in a dark field wide grazing incidence channel (DWO) using a surface roughness measuring device "Surfscan SP1-DLS" (manufactured by KLA Tencor) were used.

[0084] [Table 1]

[0085] [Table 2]

[0086] As shown in Table 2, compared to Comparative Example 21, in which polyacrylic acid (non-component B) and component C were used in combination, Examples 21 to 35, in which component B and component C were used in combination, showed improved polishing speed, significantly suppressed haze, and reduced corrosion. [Industrial Applicability]

[0087] The polishing liquid for polishing silicon substrates of the present disclosure can improve the polishing rate while reducing the surface roughness (haze) of the substrate after polishing, and can also suppress corrosion of the silicon substrate during polishing. Therefore, the polishing liquid for polishing silicon substrates of the present disclosure is particularly useful as a polishing liquid used in the manufacturing process of silicon substrates.

Claims

1. A polishing liquid for polishing silicon substrates, comprising the following components A, B, and C, and an aqueous medium: Component A: Silica particles Component B: An anionic water-soluble polymer containing a structural unit b1 derived from styrene and a structural unit b2 derived from at least one acid selected from acrylic acid, methacrylic acid, maleic acid, and salts thereof. Component C: Cationic water-soluble polymer having a basic nitrogen-containing group

2. 2. The polishing slurry for polishing silicon substrates according to claim 1, wherein the pH of the polishing slurry is greater than 8.5 and not greater than 14.

3. 2. The polishing slurry for polishing silicon substrates according to claim 1, wherein the content of the structural unit b1 in all structural units of component B is 20 mol % or more.

4. 2. The polishing slurry for polishing silicon substrates according to claim 1, wherein component C contains a structural unit derived from at least one selected from allylamine and diallylamine.

5. 5. The polishing liquid for polishing silicon substrates according to claim 4, wherein the structural unit derived from allylamine includes a structural unit having an oxygen atom at one or more positions selected from the β-position, γ-position, and δ-position of the nitrogen atom of the amino group contained in the structural unit derived from allylamine.

6. 2. The polishing slurry for polishing silicon substrates according to claim 1, wherein the zeta potential is −35 mV or more and −5 mV or less.

7. A method for polishing a silicon substrate, comprising the step of polishing a silicon substrate to be polished using the polishing slurry for polishing silicon substrates according to any one of claims 1 to 6.

8. a step of polishing a silicon substrate to be polished using the polishing slurry for polishing silicon substrates according to any one of claims 1 to 6; and cleaning the polished silicon substrate.

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