JP7396868B2 - polishing liquid composition - Google Patents

Description

The present disclosure relates to a polishing liquid composition, and a method for manufacturing and polishing a substrate using the same.

In recent years, magnetic disk drives have become smaller and larger in capacity, and higher recording densities are required. In order to increase the recording density, technology is being developed to reduce the unit recording area and to lower the flying height of the magnetic head in order to improve the detection sensitivity of weakened magnetic signals. In order to lower the flying height of the magnetic head and secure the recording area, magnetic disk substrates are designed to improve smoothness and flatness, including reduction of surface roughness, waviness, and edge sag (roll-off), as well as scratches and Requirements for reducing defects, typified by the reduction of protrusions, pits, etc., are becoming stricter.

In response to such demands, for example, Patent Document 1 discloses a polishing liquid composition containing an abrasive material, a water-soluble polymer having a phenol skeleton in the main chain or side chain, and water. Examples from the literature, Table 3).
Patent Document 2 describes (a) inorganic abrasives, (b) aryl amines, amino alcohols, aliphatic amines, heterocyclic amines, hydroxamic acids, aminocarboxylic acids, cyclic monocarboxylic acids, unsaturated monocarboxylic acids, substituted Disclosed is a polishing liquid composition comprising a polishing additive having a functional group selected from the group consisting of phenols, sulfonamides, thiols, salts thereof, and combinations thereof and having a pKa of about 3 to 9; and (c) a liquid carrier. has been done.
Patent Document 3 discloses a metal polishing liquid containing an oxidizing agent, an oxide metal dissolving agent, a first protective film forming agent, a second protective film forming agent, and water, and a preferable example of the second protective film forming agent is As such, polyacrylic acid, polyacrylamide, etc. are described (paragraph [0036] of the same document, Examples).
Patent Document 4 contains a liquid medium, abrasive grains containing a hydroxide of a tetravalent metal element, a polyoxyalkylene compound, and a cationic polymer, and the average HI.B value of the polyoxyalkylene compound is Disclosed is a polishing liquid having a particle diameter of 17.0 or less.

Special Publication No. 10-102041 Special Publication No. 2006-520530 Japanese Patent Application Publication No. 2007-142464 JP2014-207281A

With the increase in the capacity of magnetic disk drives, the requirements for the surface quality of substrates are becoming more stringent, and there is a need for the development of polishing liquid compositions that can further reduce scratches on the substrate surface. Furthermore, there is generally a trade-off relationship between polishing rate and scratches, and there is a problem that if one improves, the other worsens.

Therefore, the present disclosure provides a polishing liquid composition that can reduce scratches on the surface of a polished substrate while ensuring a polishing rate, and a method of manufacturing a magnetic disk substrate and a method of polishing the substrate using the same.

In one embodiment, the present disclosure contains an abrasive (component A), a water-soluble polymer (component B), an acid (component C), and an aqueous medium, and the component B has a phenyl ether skeleton in the main chain or side chain. The present invention relates to a polishing liquid composition, which is a cationic polymer having the following properties.

In another aspect, the present disclosure relates to a method for manufacturing a magnetic disk substrate, including a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure.

In another aspect, the present disclosure includes polishing a substrate to be polished using the polishing liquid composition of the present disclosure, wherein the substrate to be polished is a substrate used for manufacturing a magnetic disk substrate. Regarding the method.

According to the polishing composition of the present disclosure, in one or more embodiments, the effect of reducing scratches on the surface of a substrate after polishing can be achieved while ensuring a polishing rate.

The present disclosure is based on the finding that by using a polishing liquid composition containing a predetermined cationic polymer, scratches on the surface of a substrate after polishing can be reduced while ensuring a polishing rate.

That is, in one aspect, the present disclosure provides a polishing liquid composition containing an abrasive (component A), a water-soluble polymer (component B), an acid (component C), and an aqueous medium, wherein the component B is The present invention relates to a polishing liquid composition (hereinafter also referred to as "polishing liquid composition of the present disclosure"), which is a cationic polymer having a phenyl ether skeleton in its main chain or side chain.

Although the details of the mechanism by which the effects of the present disclosure are expressed are not clear, it is inferred as follows.
Generally, cationic polymers and abrasive materials such as silica abrasive grains are not used together. This is because the cationic polymer and the abrasive are likely to crosslink and aggregate due to electrostatic adsorption between the positive charge of the cationic polymer and the negative charge of the abrasive such as silica abrasive grains.
However, the specific cationic polymer (component B) of the present disclosure has low molecular mobility and is thought to have a special three-dimensional structure to suppress aggregation due to crosslinking with the abrasive material.
During polishing, the hydrophobic part (phenyl ether skeleton) of component B adsorbs to the polishing pad, making the polishing pad positively charged, attracting negatively charged abrasive material, and contributing to improving the polishing speed. Conceivable.
That is, component B suppresses the agglomeration of the abrasive in the polishing liquid composition before it is used for polishing, and has a mechanism that promotes the adsorption of the abrasive to the polishing pad while the polishing liquid composition is used for polishing. It is considered to have.
Furthermore, it is believed that the aromatic ring of component B softens the polishing pad and contributes to reducing scratches.
However, the present disclosure does not need to be interpreted as being limited to these mechanisms.

In the present disclosure, scratches on the substrate surface can be detected by, for example, an optical defect inspection device, and can be quantitatively evaluated as the number of scratches. The number of scratches can be specifically evaluated by the method described in Examples.

[Abrasive material (component A)]
As the abrasive (hereinafter also referred to as "component A") contained in the polishing liquid composition of the present disclosure, abrasives commonly used for polishing can be used, and include metals, metals, or semimetals. Examples include carbides, nitrides, oxides, borides, and diamond. The metal or metalloid element is derived from groups 2A, 2B, 3A, 3B, 4A, 4B, 5A, 6A, 7A or 8 of the periodic table (long period type). Specific examples of component A include silicon oxide (hereinafter referred to as silica), aluminum oxide (hereinafter referred to as alumina), silicon carbide, diamond, manganese oxide, magnesium oxide, zinc oxide, titanium oxide, cerium oxide (hereinafter referred to as ceria). ), zirconium oxide, etc., and it is preferable to use one or more of these from the viewpoint of improving the polishing rate. Among them, silica particles are preferable as component A from the viewpoint of ensuring a polishing rate and reducing scratches. Examples of the silica particles include colloidal silica, fumed silica, pulverized silica, and silica obtained by surface modification of these, with colloidal silica being preferred. Component A may be used alone or in combination of two or more.

The average particle diameter of component A is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, from the viewpoint of ensuring a polishing rate and reducing scratches, and from the same viewpoint, preferably 100 nm or less, and 70 nm or less. is more preferable, and even more preferably 40 nm or less. More specifically, the average particle diameter of component A is preferably 1 nm or more and 100 nm or less, more preferably 5 nm or more and 70 nm or less, and even more preferably 10 nm or more and 40 nm or less. In the present disclosure, the "average particle size of the abrasive" refers to the average particle size based on the scattering intensity distribution measured at a detection angle of 90° in a dynamic light scattering method. Specifically, the average particle size of the abrasive can be determined by the method described in Examples.

The content of component A in the polishing liquid composition of the present disclosure is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 3% by mass or more, and From the viewpoint of reducing scratches, the content is preferably 20% by mass or less, more preferably 15% by mass or less, and even more preferably 10% by mass or less. Further, from the viewpoint of ensuring a polishing rate and reducing scratches, the content of component A is preferably 0.1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less, and 3% by mass or more and 10% by mass or less. It is more preferably less than % by mass. When component A is a combination of two or more types of abrasives, the content of component A refers to their total content. In addition, when component A is silica, the content of component A is a value converted to SiO ₂ .

[Water-soluble polymer (component B)]
The water-soluble polymer used in the polishing composition of the present disclosure (hereinafter also referred to as "component B") is a cation having a phenyl ether skeleton in its main chain or side chain, from the viewpoint of ensuring a polishing rate and reducing scratches. Polymer. Component B may be used alone or in combination of two or more.

In the present disclosure, "water-soluble" means that the solubility in 100 g of a pH 3 aqueous solution at 20° C. is 0.01 g or more.

In the present disclosure, a cationic polymer refers to a polymer having a cationic group within a repeating structural unit. A cationic group refers to a functional group that becomes a cation in the presence of an acid, and includes a salt form. In one or more embodiments, the cationic group includes an organic group containing a nitrogen atom, such as an organic group having an amino group, a nitro group, an imino group, an ammonium group, and the like.

In the present disclosure, a phenyl ether skeleton refers to a structure in which at least one hydrogen atom of a benzene ring is substituted with -OX. In one or more embodiments, X is a cationic group.

In the present disclosure, the "main chain" refers to the longest part of the linear structure formed by bonding monomer units in the water-soluble polymer of component B, and the "side chain" refers to the linear chain structure formed by bonding monomer units. The part that branches off from the

In one or more embodiments, component B has a hydrophobic structural unit and a phenyl ether skeleton in which a cationic group is ether bonded in the main chain or side chain, from the viewpoint of ensuring polishing rate and reducing scratches. Preferably, a copolymer containing a structural unit having a phenol or phenyl skeleton in the main chain or side chain, and a structural unit having a phenyl ether skeleton in which a cationic group is ether-bonded in the main chain or side chain. More preferably, a copolymer containing a structural unit having a phenol skeleton in a side chain and a structural unit having a phenyl ether skeleton in a side chain in which a cationic group is ether-bonded is even more preferable. Here, the phenol skeleton refers to a structure in which at least one hydrogen atom of a benzene ring is substituted with a hydroxy group.

One embodiment of component B includes, for example, a compound having a structure represented by the following formula (I).

In formula (I), X represents a cationic group. From the viewpoint of ensuring a polishing rate and reducing scratches, X is preferably a cationic group containing a nitrogen atom, more preferably a cationic group containing a nitrogen atom and having 1 to 20 carbon atoms, an amino group, a nitro group, etc. , an imino group, and an ammonium group, and a cationic group having 1 or more and 20 or less carbon atoms is more preferable. From the viewpoint of ensuring a polishing rate and reducing scratches, the number of carbon atoms in the cationic group is preferably 1 or more and 20 or less, more preferably 2 or more and 15 or less, and even more preferably 3 or more and 12 or less.

Examples of X in formula (I) include -R ⁶ N(R ⁷ )(R ⁸ ) and -R ⁶ N ⁺ (R ⁷ )(R ⁸ )(R ⁹ )·Y ^- . From the viewpoint of securing a polishing rate and reducing scratches, R ⁶ is preferably a linear or branched alkylene group having 1 to 5 carbon atoms, and more preferably a linear alkylene group having 1 to 5 carbon atoms. R ⁷ to R ⁹ are each independently preferably a hydrogen atom or a linear or branched hydrocarbon group having 1 to 5 carbon atoms, and preferably a hydrogen atom or a straight or branched hydrocarbon group having 1 to 5 carbon atoms. An alkyl group is more preferred, at least one of a methyl group and an ethyl group is even more preferred, and a methyl group is even more preferred. Y ^- represents an anion. Examples of anions include halide ions such as chloride ions, bromide ions, and fluoride ions; sulfate ions; phosphate ions; nitrate ions; and the like.

In formula (I), m/n is preferably 20/80 to 80/20, more preferably 25/75 to 70/30, and more preferably 35/65 to 70/30 from the viewpoint of ensuring polishing rate and reducing scratches. is more preferable, 35/65 to 55/45 is even more preferable, and 40/60 to 50/50 is even more preferable.

In one or more embodiments, the content of the structure represented by formula (I) in all the structural units constituting component B is preferably 50 mol% or more from the viewpoint of ensuring a polishing rate and reducing scratches. , more preferably 80 mol% or more, still more preferably 90 mol% or more, and most preferably 100 mol%.

In the present disclosure, depending on the synthesis conditions, the content (mol%) of a certain structural unit in all the structural units constituting component B may include all the structural units charged in the reaction tank during all steps of the synthesis of component B. The amount (mol %) of the compound for introducing the structural unit charged in the reaction tank in the compound for introduction may be used. In addition, in the present disclosure, when component B includes two or more types of structural units, the composition ratio (molar ratio) of the two structural units may vary depending on the synthesis conditions. The compound amount ratio (molar ratio) for introducing the two structural units may be used.

Component B may have other structural units not included in formula (I). The content of other structural units in all the structural units constituting component B is preferably 10 mol% or less, more preferably 5 mol% or less, and 3 mol% or less, from the viewpoint of ensuring a polishing rate and reducing scratches. is more preferable, 1 mol% or less is even more preferable, and even more preferably substantially 0 mol%.

Component B, in one embodiment, can be prepared by a Mannich reaction using a dialkylamine and formaldehyde. In other embodiments, component B can be produced by polymerizing a polymer containing a phenol skeleton with an alkylamine halogen compound.

The arrangement of the constituent units constituting component B may be random, block, or grafted.

The weight average molecular weight of component B is preferably 500 or more, more preferably 1,000 or more, even more preferably 1,500 or more, and from the same viewpoint, 1,000 or more. ,000 or less, more preferably 750,000 or less, even more preferably 500,000 or less. More specifically, the weight average molecular weight of component B is preferably 500 or more and 1,000,000 or less, more preferably 1,000 or more and 750,000 or less, and still more preferably 1,500 or more and 500,000 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.

The content of component B in the polishing liquid composition of the present disclosure is preferably 0.000001% by mass or more, more preferably 0.00001% by mass or more, and 0.0001% by mass from the viewpoint of ensuring a polishing rate and reducing scratches. % or more, more preferably 0.0005% by mass or more, even more preferably 0.0015% by mass or more, and from the same point of view, preferably 0.01% by mass or less, and more preferably less than 0.01% by mass. It is preferably 0.009% by mass or less, more preferably 0.006% by mass or less, even more preferably 0.004% by mass or less, even more preferably 0.0025% by mass or less. More specifically, the content of component B is preferably 0.000001% by mass or more and 0.01% by mass or less, more preferably 0.00001% by mass or more and 0.01% by mass or less, and 0.0001% by mass or more. It is more preferably 0.009% by mass or less, even more preferably 0.0005% by mass or more and 0.006% by mass or less, even more preferably 0.0015% by mass or more and 0.004% by mass or less.

The mass ratio of component B to component A in the polishing liquid composition of the present disclosure (content of component B/content of component A) is preferably 0.0000002 or more from the viewpoint of ensuring polishing speed and reducing scratches. The above is more preferable, 0.000002 or more is still more preferable, 0.0001 or more is still more preferable, 0.0003 or more is still more preferable, and from the same viewpoint, 0.02 or less is preferable, and 0.01 or less is more preferable. , more preferably 0.005 or less, even more preferably 0.003 or less, even more preferably 0.0008 or less. More specifically, the mass ratio of component B to component A is preferably 0.0000002 or more and 0.02 or less, more preferably 0.000002 or more and 0.01 or less, and even more preferably 0.000002 or more and 0.005 or less. , more preferably 0.0001 or more and 0.003 or less, and even more preferably 0.0003 or more and 0.0008 or less.

[Acid (component C)]
The polishing liquid composition of the present disclosure contains an acid (component C). In this disclosure, the use of acids includes the use of acids and/or salts thereof. Component C may be used alone or in combination of two or more.

Component C includes, for example, inorganic acids such as nitric acid, sulfuric acid, sulfite, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid; organic phosphoric acid, organic phosphonic acid; Examples include organic acids such as acids and carboxylic acids. Among these, at least one selected from inorganic acids and organic phosphonic acids is preferred from the viewpoint of ensuring a polishing rate and reducing scratches. The inorganic acid is preferably at least one selected from nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, and phosphoric acid, and more preferably at least one of phosphoric acid and sulfuric acid. As the organic phosphonic acid, at least one selected from 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotri(methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), and diethylenetriaminepenta(methylenephosphonic acid) is used. Preferably, HEDP is more preferable. Examples of the salts of these acids include salts of the above acids and at least one selected from metals, ammonia, and alkyl amines. Specific examples of the above metals include metals belonging to groups 1 to 11 of the periodic table. Among these, salts of the above acids and metals belonging to Group 1A or ammonia are preferred from the viewpoint of ensuring a polishing rate and reducing scratches.

The content of component C in the polishing liquid composition of the present disclosure is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and 0.4% by mass from the viewpoint of ensuring polishing speed and reducing scratches. % or more, and from the same viewpoint, 5% by mass or less is preferable, more preferably 3% by mass or less, and even more preferably 2% by mass or less. More specifically, the content of component C is preferably 0.01% by mass or more and 5% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, and 0.4% by mass or more and 2% by mass or less. is even more preferable. When component C consists of two or more types of acids, the content of component C refers to their total content.

The mass ratio C/A (content of component C/content of component A) of component C to component A in the polishing liquid composition of the present disclosure is 0.002 or more from the viewpoint of ensuring polishing rate and reducing scratches. is preferable, 0.02 or more is more preferable, 0.08 or more is still more preferable, and from the same viewpoint, 1 or less is preferable, 0.6 or less is more preferable, and 0.5 or less is still more preferable. More specifically, the mass ratio C/A is preferably 0.002 or more and 1 or less, more preferably 0.02 or more and 0.6 or less, and even more preferably 0.08 or more and 0.5 or less.

[Aqueous medium]
Examples of the aqueous medium included in the polishing liquid composition of the present disclosure include water such as distilled water, ion exchange water, pure water, and ultrapure water, or a mixed solvent of water and a solvent. Examples of the solvent include solvents that are miscible with water (for example, alcohols such as ethanol). When the aqueous medium is a mixed solvent of water and a solvent, the proportion of water to the entire mixed medium may not be particularly limited as long as the effects of the present disclosure are not hindered, and from an economical point of view, for example, , is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably substantially 100% by mass. From the viewpoint of surface cleanliness of the substrate to be polished, ion exchange water and ultrapure water are preferable as the aqueous medium. The content of the aqueous medium in the polishing liquid composition of the present disclosure can be the remainder after removing component A, component B, component C, and optional components described below that are blended as necessary.

[Oxidizing agent (component D)]
The polishing liquid composition of the present disclosure may further contain an oxidizing agent (hereinafter also referred to as "component D") from the viewpoint of ensuring a polishing rate and reducing scratches. Component D, in one or more embodiments, is an oxidizing agent that does not contain a halogen atom. Component D may be used alone or in combination of two or more.

From the viewpoint of ensuring a polishing rate and reducing scratches, component D includes, for example, peroxide, permanganic acid or its salt, chromic acid or its salt, peroxo acid or its salt, oxygen acid or its salt, metal salts, Examples include nitric acids and sulfuric acids. Among these, at least one selected from hydrogen peroxide, iron(III) nitrate, peracetic acid, ammonium peroxodisulfate, iron(III) sulfate, and ammonium iron(III) sulfate is preferable, from the viewpoint of improving the polishing rate, and from the substrate to be polished. Hydrogen peroxide is more preferred from the viewpoint of metal ions not adhering to the surface of the hydrogen peroxide and from the viewpoint of easy availability.

The content of component D in the polishing liquid composition of the present disclosure is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and 0.1% by mass from the viewpoint of ensuring polishing speed and reducing scratches. The above is more preferable, and the content is preferably 4% by mass or less, more preferably 2% by mass or less, and even more preferably 1.5% by mass or less. More specifically, the content of component D is preferably 0.01% by mass or more and 4% by mass or less, more preferably 0.05% by mass or more and 2% by mass or less, and 0.1% by mass or more and 1.5% by mass. % or less is more preferable. When component D consists of two or more oxidizing agents, the content of component D refers to their total content.

[Heterocyclic aromatic compound (component E)]
The polishing liquid composition of the present disclosure may further contain a heterocyclic aromatic compound (including a salt thereof) (component E). There may be one type of component E, or two or more types may be used.

From the viewpoint of reducing scratches, component E is preferably a heterocyclic aromatic compound containing two or more nitrogen atoms in the heterocycle, more preferably three or more nitrogen atoms in the heterocycle, The number is more preferably 3 or more and 9 or less, more preferably 3 or more and 5 or less, and even more preferably 3 or 4.

Specific examples of component E include 1,2,4-triazole, 3-amino-1,2,4-triazole, 5-amino-1,2,4-triazole, 3-mercapto-1,2,4- Triazole, 1H-tetrazole, 5-aminotetrazole, 1H-benzotriazole (BTA), 1H-tolyltriazole, 2-aminobenzotriazole, 3-aminobenzotriazole, and alkyl-substituted or amine-substituted products thereof are preferred. Examples of the alkyl group of the alkyl substituent include a lower alkyl group having 1 to 4 carbon atoms, and more specifically, a methyl group and an ethyl group. Examples of the amine substituted product include 1-[N,N-bis(hydroxyethylene)aminomethyl]benzotriazole and 1-[N,N-bis(hydroxyethylene)aminomethyl]tolyltriazole.

From the viewpoint of reducing scratches, the content of component E in the polishing liquid composition of the present disclosure is preferably 0.005% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more. , and preferably 10% by mass or less, more preferably 5% by mass or less, even more preferably 1% by mass or less. More specifically, the content of component E is preferably 0.005% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 5% by mass or less, and 0.02% by mass or more and 1% by mass or less. is even more preferable. When component E consists of two or more types of heterocyclic aromatic compounds, the content of component E refers to their total content.

[Aliphatic amine compound or alicyclic amine compound (component F)]
The polishing liquid composition of the present disclosure may further contain an aliphatic amine compound or an alicyclic amine compound (component F) from the viewpoint of reducing scratches. From the viewpoint of reducing scratches, the number of nitrogen atoms or the total number of amino groups or imino groups in the molecule of component F is preferably 2 or more and 4 or less. Component F may be used alone or in combination of two or more.

From the viewpoint of reducing scratches, examples of the aliphatic amine compounds include ethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, and 1,4-diaminobutane. , hexamethylenediamine, 3-(diethylamino)propylamine, 3-(dibutylamino)propylamine, 3-(methylamino)propylamine, 3-(dimethylamino)propylamine, N-aminoethylethanolamine, N-amino At least one selected from ethylisopropanolamine and N-aminoethyl-N-methylethanolamine is preferable, and from N-aminoethylethanolamine, N-aminoethylisopropanolamine, and N-aminoethyl-N-methylethanolamine. At least one selected one is more preferred, and N-aminoethylethanolamine (AEA) is even more preferred.

From the viewpoint of reducing scratches, the alicyclic amine compounds include piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 1-amino-4-methylpiperazine, N-methylpiperazine, and hydroxyethylpiperazine (HEP). At least one selected from these is preferred, and hydroxyethylpiperazine (HEP) is more preferred.

From the viewpoint of reducing scratches, the content of component F in the polishing liquid composition of the present disclosure is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and preferably 10% by mass or less, The content is more preferably 5% by mass or less, and even more preferably 1% by mass or less. More specifically, the content of component F is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.02% by mass or more and 5% by mass or less, and 0.02% by mass or more and 1% by mass or less. is even more preferable. When component F consists of two or more types of aliphatic amine compounds and/or alicyclic amine compounds, the content of component F refers to their total content.

[Other ingredients]
In one or more embodiments, the polishing liquid composition of the present disclosure may further contain other components as necessary. Other components include, for example, water-soluble polymers other than component B, thickeners, dispersants, rust preventives, basic substances, surfactants, solubilizers, and the like. The content of the other components in the polishing liquid composition of the present disclosure is preferably 0% by mass or more, more preferably more than 0% by mass, even more preferably 0.1% by mass or more, and 10% by mass or less. It is preferably 5% by mass or less, and more preferably 5% by mass or less. More specifically, the content of other components is preferably 0 mass% or more and 10 mass% or less, more preferably more than 0 mass% and 10 mass% or less, and even more preferably 0.1 mass% or more and 5 mass% or less. .

[pH of polishing liquid composition]
The pH of the polishing liquid composition of the present disclosure is preferably 6 or less, more preferably 5 or less, even more preferably 4 or less, even more preferably 3 or less, from the viewpoint of ensuring a polishing rate and reducing scratches, and from the same viewpoints. , preferably 0.5 or more, more preferably 0.8 or more, and even more preferably 1 or more. More specifically, the pH of the polishing liquid composition of the present disclosure is preferably 0.5 or more and 6 or less, more preferably 0.8 or more and 5 or less, and even more preferably 1 or more and 4 or less. The pH can be adjusted using the above-mentioned acid (component C), a known pH adjuster, or the like. In the present disclosure, the above-mentioned pH is the pH of the polishing liquid composition at 25°C, and can be measured using a pH meter, for example, the value obtained 2 minutes after immersing the electrode of the pH meter in the polishing liquid composition. be able to.

[Method for manufacturing polishing liquid composition]
The polishing liquid composition of the present disclosure can be produced by, for example, blending component A, component B, component C, an aqueous medium, and, if desired, components D to F and other components by a known method. That is, 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, component B, component C, and an aqueous medium. In the present disclosure, "blending" includes mixing component A, component B, component C, and the aqueous medium, and if necessary, components D to G and other components simultaneously or in any order. The abrasive material of component A may be mixed in the form of a concentrated slurry, or may be mixed after being diluted with water or the like. When component A consists of multiple types of abrasives, the multiple types of abrasives can be blended simultaneously or separately. When component B consists of multiple types of cationic polymers, the multiple types of cationic polymers can be blended simultaneously or separately. When component C consists of multiple types of acids, the multiple types of acids can be blended simultaneously or separately. The blending can be performed using a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. The preferred blending amount of each component in the method for producing a polishing liquid composition can be the same as the preferred content of each component in the polishing liquid composition of the present disclosure described above.

In the present disclosure, "the content of each component in the polishing liquid composition" refers to the content of each of the components at the time of use, that is, at the time when the polishing liquid composition starts to be used for polishing. The polishing liquid composition of the present disclosure may be stored and supplied in a concentrated state as long as its storage stability is not impaired. This case is preferable in that manufacturing and transportation costs can be further reduced. The concentrate of the polishing liquid composition of the present disclosure may be appropriately diluted with the above-mentioned aqueous medium as necessary at the time of use. The dilution ratio is not particularly limited as long as the above-mentioned content of each component (at the time of use) can be ensured after dilution, and can be, for example, 10 to 100 times.

[Polishing liquid kit]
In other aspects, the present disclosure relates to a kit for manufacturing the polishing liquid composition of the present disclosure (hereinafter also referred to as "polishing liquid kit of the present disclosure"). An embodiment of the polishing liquid kit of the present disclosure includes, for example, an abrasive dispersion containing component A and an aqueous medium and an aqueous additive solution containing components B and C in a state that they are not mixed with each other. A liquid kit (two-part polishing liquid composition) is mentioned. The abrasive dispersion liquid and the additive aqueous solution are mixed at the time of use, and diluted with an aqueous medium as necessary. The aqueous medium contained in the abrasive dispersion may be the entire amount of water used for preparing the polishing liquid composition, or may be a portion thereof. The additive aqueous solution may contain a part of the aqueous medium used for preparing the polishing liquid composition. The abrasive dispersion liquid and the additive aqueous solution may each contain the above-mentioned optional components (components D to F and other components) as necessary. According to the polishing liquid kit of the present disclosure, it is possible to obtain a polishing liquid composition that can reduce scratches on the surface of a substrate after polishing while ensuring a polishing rate.

[Substrate to be polished]
In one or more embodiments, the substrate to be polished is a substrate used for manufacturing a magnetic disk substrate. In one or more embodiments, after the step of polishing the surface of the substrate to be polished using the polishing liquid composition of the present disclosure, the magnetic disk substrate is polished by forming a magnetic layer on the surface of the substrate by sputtering or the like. can be manufactured.

The material of the substrate to be polished preferably used in the present disclosure includes, for example, metals or semimetals such as silicon, aluminum, nickel, tungsten, copper, tantalum, and titanium, or alloys thereof, glass, glassy carbon, and amorphous. Examples include glassy substances such as carbon, ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride, and titanium carbide, and resins such as polyimide resin. Among these, it is suitable for polished substrates containing metals such as aluminum, nickel, tungsten, and copper, and alloys containing these metals as main components. As the substrate to be polished, for example, Ni-P plated aluminum alloy substrates, crystallized glass, tempered glass, aluminosilicate glass, aluminoborosilicate glass, and other glass substrates are more suitable; Aluminum alloy substrates are more suitable. In the present disclosure, "Ni--P plated aluminum alloy substrate" refers to an aluminum alloy base material whose surface is ground and then subjected to electroless Ni--P plating.

Examples of the shape of the substrate to be polished include shapes having a flat portion such as a disk shape, plate shape, slab shape, and prism shape, and shapes having a curved surface portion such as a lens. Among these, a disk-shaped substrate to be polished is suitable. In the case of a disk-shaped substrate to be polished, its outer diameter is, for example, about 2 to 95 mm, and its thickness is, for example, about 0.4 to 2 mm.

[Method for manufacturing magnetic disk substrate]
Generally, a magnetic disk is manufactured by polishing a substrate to be polished that has undergone a grinding process, a rough polishing process and a final polishing process, and then forming a magnetic disk in a recording section forming process. The polishing liquid composition according to the present disclosure can be used in a polishing step of polishing a substrate to be polished, preferably in a final polishing step in a method for manufacturing a magnetic disk substrate. That is, in other aspects, the present disclosure includes a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure (hereinafter also referred to as "polishing step using the polishing liquid composition of the present disclosure"). , relates to a method for manufacturing a magnetic disk substrate (hereinafter also referred to as "substrate manufacturing method of the present disclosure"). The substrate manufacturing method of the present disclosure is particularly suitable for manufacturing a magnetic disk substrate for perpendicular magnetic recording.

In one or more embodiments, the polishing step using the polishing liquid composition of the present disclosure includes supplying the polishing liquid composition of the present disclosure to a surface to be polished of a substrate to be polished, and bringing a polishing pad into contact with the surface to be polished. This step is a step of polishing by moving at least one of the polishing pad and the substrate to be polished. In addition, in one or more other embodiments, the polishing process using the polishing liquid composition of the present disclosure is performed by polishing the substrate to be polished using a surface plate to which a polishing pad such as a non-woven organic polymer polishing cloth is attached. In this step, the substrate to be polished is polished by moving the surface plate and the substrate to be polished while sandwiching and supplying the polishing liquid composition of the present disclosure to a polishing machine.

When the polishing process of the substrate to be polished is performed in multiple stages, the polishing process using the polishing liquid composition of the present disclosure is preferably performed in the second stage or later, and is preferably performed in the final polishing process or final polishing process. is more preferable. At that time, in order to avoid contamination with the abrasive material or polishing liquid composition from the previous process, separate polishing machines may be used for each polishing machine, and if separate polishing machines are used, each polishing process Preferably, the substrate is cleaned. Furthermore, the polishing liquid composition of the present disclosure can also be used in cyclic polishing in which the used polishing liquid is reused. The polishing machine is not particularly limited, and any known polishing machine for substrate polishing can be used.

The polishing pad used in the present disclosure is not particularly limited. For example, a polishing pad of suede type, non-woven fabric type, polyurethane closed foam type, or a two-layer type in which these are laminated can be used. From this point of view, suede type polishing pads are preferred.

The polishing load in the polishing step using the polishing liquid composition of the present disclosure is preferably 5.9 kPa or more, more preferably 6.9 kPa or more, still more preferably 7.5 kPa or more, from the viewpoint of ensuring a polishing rate, From the viewpoint of reducing scratches, the pressure is preferably 20 kPa or less, more preferably 18 kPa or less, even more preferably 16 kPa or less. More specifically, the polishing load is preferably 5.9 to 20 kPa, more preferably 6.9 to 18 kPa, and even more preferably 7.5 to 16 kPa. In the manufacturing method of the present disclosure, the polishing load refers to the pressure of a surface plate applied to the polishing surface of the substrate to be polished during polishing. Further, the polishing load can be adjusted by applying air pressure or weight to at least one of the surface plate and the substrate to be polished.

The supply rate of the polishing liquid composition of the present disclosure in the polishing process using the polishing liquid composition of the present disclosure is preferably 0.05 mL/min or more and 15 mL/min or less per 1 cm ² of the substrate to be polished, from the viewpoint of scratch reduction. More preferably, it is 0.06 mL/min or more and 10 mL/min or less, still more preferably 0.07 mL/min or more and 1 mL/min or less, and still more preferably 0.07 mL/min or more and 0.5 mL/min or less.

Examples of a method for supplying the polishing liquid composition of the present disclosure to a polishing machine include a method of continuously supplying the composition using a pump or the like. When supplying the polishing liquid composition to the polishing machine, in addition to supplying it as a single liquid containing all the components, considering the stability of the polishing liquid composition, etc., it is divided into multiple component liquids for blending. It is also possible to supply two or more liquids. In the latter case, the plurality of compounding component liquids are mixed, for example, in the supply piping or on the substrate to be polished, to form the polishing liquid composition of the present disclosure.

According to the substrate manufacturing method of the present disclosure, by using the polishing liquid composition of the present disclosure, a high-quality magnetic disk substrate with reduced scratches on the substrate surface after polishing can be manufactured with high yield and productivity. The effect of being able to do this can be achieved.

[Polishing method]
In another aspect, the present disclosure relates to a method for polishing a substrate (hereinafter also referred to as "the polishing method of the present disclosure"), which includes polishing a substrate to be polished using the polishing liquid composition of the present disclosure. By using the polishing method of the present disclosure, it is possible to produce a high-quality magnetic disk substrate with reduced scratches on the surface of the substrate after polishing, with high yield and with good productivity. As described above, the substrate to be polished in the polishing method of the present disclosure includes those used for manufacturing magnetic disk substrates, and among them, substrates used for manufacturing magnetic disk substrates for perpendicular magnetic recording systems are preferred. The specific polishing method and conditions can be the same as those of the substrate manufacturing method of the present disclosure described above.

In one or more embodiments, polishing a substrate to be polished using the polishing liquid composition of the present disclosure includes supplying the polishing liquid composition of the present disclosure to the surface to be polished of the substrate to be polished, and polishing the surface to be polished using the polishing liquid composition of the present disclosure. A polishing pad is brought into contact with the polishing pad and at least one of the polishing pad and the substrate to be polished is moved to perform polishing. This involves sandwiching the polishing substrate and polishing the substrate by moving the surface plate and the substrate to be polished while supplying the polishing liquid composition of the present disclosure to a polishing machine.

Hereinafter, the present disclosure will be explained in more detail with reference to Examples, but these are merely illustrative and the present disclosure is not limited to these Examples.

1. Water-soluble polymers The following were used as water-soluble polymers B1 to B10 shown in Table 1.
B1: Poly-p-vinylphenol/poly[N,N-dimethyl-1-(4-vinylphenoxy)methanamine] (mole ratio 45/55) [Product name: MAM3ME, manufactured by Maruzen Petrochemical Co., Ltd., weight average molecular weight 5 ,000] (X in formula I: dimethylaminomethyl group)
B2: Poly-p-vinylphenol/poly[N,N-dimethyl-1-(4-vinylphenoxy)methanamine] (molar ratio 30/70) (synthetic product) [manufactured by Maruzen Petrochemical Co., Ltd., weight average molecular weight 5, 000] (X in formula I: dimethylaminomethyl group)
B3: Polyallylamine [Product name: PAA-05, manufactured by Nitto Bo Medical Co., Ltd., weight average molecular weight 5,000]
B4: Poly N-methyldiallylamine hydrochloride [Product name: PAS-M-1L, manufactured by Knit-Beau Medical, weight average molecular weight 5,000]
B5: Poly-p-vinylphenol [manufactured by Nippon Soda Co., Ltd., weight average molecular weight 4,400]
B6: Polyacrylic acid [manufactured by Toagosei Co., Ltd., weight average molecular weight 3,000]
B7: Aromatic aminosulfonic acid [Product name: Floric SF200S, manufactured by Floric Co., Ltd.]
B8: p-aminophenol (monomer) [manufactured by Tokyo Kasei Kogyo Co., Ltd., molecular weight 109.13]
B9: Poly-p-vinylphenol/poly[N,N-dimethyl-1-(4-vinylphenoxy)methanamine] (mole ratio 45/55) [weight average molecular weight 2,500] (X in formula I: dimethyl aminomethyl group)
B10: Poly-p-vinylphenol/poly[N,N-dimethyl-1-(4-vinylphenoxy)methanamine] (mole ratio 45/55) [weight average molecular weight 12,000] (X in formula I: dimethyl aminomethyl group)
The solubility of B1 to B4 and B6 to B10 in 100 g of an aqueous solution of pH 3 at 20° C. is 0.01 g or more, and that of B5 is less than 0.01 g.

2. Preparation of polishing liquid composition (polishing liquid compositions of Examples 1 to 10 and Comparative Examples 1 to 7)
Component A (colloidal silica), component B or non-component B (water-soluble polymers B1 to B10 shown in Table 1), component C (phosphoric acid), component D (hydrogen peroxide), and ion-exchanged water are blended. By stirring, polishing liquid compositions of Examples 1 to 10 and Comparative Examples 1 to 7 shown in Table 2 were prepared. The content (effective amount) of each component in each polishing liquid composition is as shown in Table 2. The content of ion-exchanged water is the remainder after removing component A, component B or non-component B, component C, and component D.
(Polishing liquid composition of Examples 11-12)
Component A (colloidal silica), component B (water-soluble polymer B1 shown in Table 1), component C (phosphoric acid), component D (hydrogen peroxide), other additives (component E: BTA, or component F :HEP) and ion-exchanged water and stirred to prepare polishing liquid compositions of Examples 11 and 12 shown in Table 2. The content (effective amount) of each component in each polishing liquid composition is as shown in Table 2 for components A to D, and 0.02% by mass for component E or component F. The content of ion-exchanged water is the remainder after removing component A, component B, component C, component D, and other additives (component E or component F).

In preparing each polishing liquid composition, the following were used as components C to F.
Phosphoric acid [manufactured by Wako Pure Chemical Industries, Ltd., special grade] (component C)
Hydrogen peroxide solution [concentration 35% by mass, manufactured by ADEKA] (component D)
BTA [1,2,3-benzotriazole, manufactured by Tokyo Kasei Kogyo Co., Ltd.] (Component E)
HEP [N-hydroxyethylpiperazine, manufactured by Wako Pure Chemical Industries, Ltd.] (Component F)

2. Measurement of each parameter (1) Average particle size of colloidal silica (component A) Component A (colloidal silica) and component C (phosphoric acid) used in the preparation of the polishing liquid composition were added to ion exchange water and stirred. A standard sample was prepared by doing this. The contents of component A and component C in the standard sample were 1% by mass and 0.45% by mass, respectively. The area of the scattered intensity distribution obtained by the Cumulant method at a detection angle of 90° when this standard sample was integrated 200 times using a dynamic light scattering device (Otsuka Electronics DLS-6500) according to the instructions attached by the manufacturer. The particle size at which 50% of the total was determined was determined and was defined as the average particle size of colloidal silica. The results are shown in Table 2.

(2) Weight average molecular weight of water-soluble polymer (component B and non-component B) The weight average molecular weight of component B and non-component B was measured by gel permeation chromatography (GPC) under the following conditions. The results are shown in Tables 1 and 2.
<Measurement conditions>
Column: TSKgel GMPWXL+TSKgel GMPWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer/CH ₃ CN = 7/3 (volume ratio)
Temperature: 40℃
Flow rate: 1.0mL/min Sample size: 2mg/mL
Detector: RI
Standard substance: Sodium polystyrene sulfonate (weight average molecular weight: 1,100, 3,610, 14,900, 152,000, manufactured by POLMER STANDARDS SERVICE)

(3) Measurement of pH The pH of the polishing liquid composition was measured at 25°C using a pH meter (manufactured by Toa DKK Co., Ltd.), and the value obtained 2 minutes after immersing the electrode in the polishing liquid composition was adopted. . The results are shown in Table 2.

3. Polishing Method Using the polishing liquid compositions of Examples 1 to 12 and Comparative Examples 1 to 7 prepared as described above, the following substrates to be polished were polished under the polishing conditions shown below. Next, the polishing speed and number of scratches were measured. The results are shown in Table 2.

[Substrate to be polished]
As the substrate to be polished, a Ni--P plated aluminum alloy substrate was used, which had been roughly polished in advance with a polishing liquid composition containing an alumina abrasive. This substrate to be polished had a thickness of 1.27 mm, an outer diameter of 95 mm, an inner diameter of 25 mm, and a center line average roughness Ra of 1 nm as measured by AFM (Digital Instrument NanoScope IIIa Multi Mode AFM).

[Polishing conditions]
Polishing tester: "Double-sided 9B polishing machine" manufactured by Speed Fam Co., Ltd.
Polishing pad: Fujibo suede type (foam layer: polyurethane elastomer, thickness 0.9 mm, average pore diameter 10 μm)
Polishing liquid composition supply amount: 100 mL/min (supply rate per 1 cm ² of substrate to be polished: 0.076 mL/min)
Lower surface plate rotation speed: 32.5 rpm
Polishing load: 13.0kPa
Polishing time: 6 minutes Number of substrates: 10

4. Evaluation [Evaluation of polishing speed]
The weight of each substrate before and after polishing was measured using a BP-210S manufactured by Sartorius, and the amount of mass reduction was determined from the change in mass of each substrate. The polishing rate was calculated by dividing the average mass loss of all 10 sheets by the polishing time, and calculated using the following formula. The measurement results of the polishing rate are shown in Table 2 as relative values with Comparative Example 1 set as 100.
Mass reduction (g) = {mass before polishing (g) - mass after polishing (g)}
Polishing speed (mg/min) = mass reduction amount (mg) / polishing time (min)

[Scratch evaluation]
Measuring equipment: “Candela OSA7100” manufactured by KLA/Tencor Co., Ltd.
Evaluation: Four substrates were randomly selected from among the substrates put into the polishing tester, and each substrate was irradiated with a laser at 10,000 rpm to measure the number of scratches. The total number of scratches (numbers) on both sides of each of the four substrates was divided by 8 to calculate the number of scratches per substrate surface. The evaluation results of the number of scratches are shown in Table 2 as relative values with Comparative Example 1 set as 100.

As shown in Table 2 above, the polishing liquid compositions of Examples 1 to 12 effectively reduced scratches while maintaining the polishing rate compared to the polishing liquid compositions of Comparative Examples 1 to 7.

According to the present disclosure, for example, a magnetic disk substrate suitable for increasing recording density can be provided.

Claims (10)

Contains an abrasive (component A), a water-soluble polymer (component B), an acid (component C) and an aqueous medium,
Component B is a cationic polymer having a phenyl ether skeleton in the main chain or side chain , and a phenyl ether in which a constitutional unit having a phenol skeleton in the main chain or side chain and a cationic group are ether bonded. A polishing liquid composition which is a copolymer comprising a structural unit having a skeleton in a main chain or a side chain . The polishing liquid composition according to claim 1 , wherein the component B is a compound having a structure represented by the following formula (I).

In formula (I), X represents a cationic group, and m/n is 20/80 to 80/20. The polishing liquid composition according to claim 1 or 2 , wherein the content of component B is 0.01% by mass or less. The polishing liquid composition according to any one of claims 1 to 3 , wherein component A is silica. The polishing liquid composition according to any one of claims 1 to 4 , further comprising an oxidizing agent. The polishing liquid composition according to any one of claims 1 to 5 , further comprising at least one selected from a heterocyclic aromatic compound, an aliphatic amine compound, and an alicyclic amine compound. The polishing liquid composition according to any one of claims 1 to 6 , wherein the polishing liquid composition is a polishing liquid composition for magnetic disk substrates. The polishing liquid composition according to any one of claims 1 to 7 , having a pH of 6 or less. A method for manufacturing a magnetic disk substrate, comprising a polishing step of polishing a substrate to be polished using the polishing liquid composition according to any one of claims 1 to 8 . A method for polishing a substrate, the method comprising polishing a substrate to be polished using the polishing liquid composition according to any one of claims 1 to 8 , wherein the substrate to be polished is a substrate used for manufacturing a magnetic disk substrate. .