Polishing liquid

Abstract

To provide polishing liquid capable of enhancing a polishing speed without increasing scratches even on a thinned substrate.SOLUTION: In one embodiment, the present invention relates to a polishing liquid comprising: silica particles (component A); a compound (component B) represented by the following structural formula (I); a water-soluble polymer (component C) containing a structural unit derived from a monomer having a carboxy group; and an aqueous medium. Defining the number of moles of nitrogen atoms in component B as B (mol) and the number of moles of carboxy groups in component C as C (mol), the polishing liquid satisfies the following formula (II). R1-N(R2)-(CH2)n-N(R3)-R4-X (I) and B / C<0.8 (II).SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a polishing liquid, a method for manufacturing a magnetic disk substrate, a method for polishing a substrate, and a method for improving the polishing rate of a substrate.

Background Art

[0002] In recent years, magnetic disk drives have been miniaturized and increased in capacity, and higher recording density has been demanded. To achieve higher recording density, it is necessary to reduce the unit recording area and improve the detection sensitivity of the weakened magnetic signal. Therefore, technological development has been promoted to lower the flying height of the magnetic head. For the magnetic disk substrate to meet these requirements, the requirements for improving smoothness and flatness (reduction of surface roughness, waviness, and end face sag) and reducing surface defects (reduction of residual abrasive grains, scratches, protrusions, pits, etc.) have become stricter.

[0003] In response to such requirements, from the perspective of achieving both improved surface quality such as smoother and less scratched surfaces and improved productivity, in the method for manufacturing a magnetic disk substrate, a multi-stage polishing method having two or more polishing steps is often adopted. Generally, to meet the requirement of smoothness, an abrasive containing colloidal silica particles is used, and from the perspective of improving productivity, a polishing liquid containing alumina particles as abrasive grains is used. However, when alumina particles are used as abrasive grains, defects may be caused on the magnetic disk substrate due to the penetration of the alumina particles into the substrate.

[0004] Therefore, for example, Patent Documents 1 and 2 propose a polishing liquid composition that does not contain alumina particles and contains silica particles as abrasive grains.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, the thinning of substrates has also advanced. When the thickness of the substrate decreases, the amount of polishing liquid acting on the substrate decreases, and it tends to be unable to ensure a sufficient polishing rate. Also, generally, there is a problem that the polishing rate and scratches are in a trade-off relationship, that is, when one improves, the other deteriorates.

[0007] Therefore, the present disclosure provides a polishing liquid capable of improving the polishing rate without increasing scratches even in a thinned substrate, and a method for manufacturing a magnetic disk substrate using the same.

Means for Solving the Problems

[0008] In one aspect, the present disclosure is a polishing liquid containing silica particles (component A), a compound represented by the following structural formula (I) (component B), a water-soluble polymer (component C) containing a structural unit c1 derived from a monomer having a carboxy group, and an aqueous medium. When the number of moles of nitrogen atoms of component B contained in the polishing liquid is B (mol) and the number of moles of carboxy groups of component C is C (mol), it relates to a polishing liquid that satisfies the following formula (II). R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X···(I) In the structural formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a hydrocarbon group, R 4 is a bond or a hydrocarbon group, and X is selected from any one of a hydrogen atom, a hydroxyl group, and an amino group. R 2 and R 3 may be bonded to each other to form a cyclic structure. n is an integer of 1 or more and 15 or less. B / C < 0.8 ···(II)

[0009] In one aspect, the present disclosure relates to a method for manufacturing a magnetic disk substrate, including a polishing step of polishing a substrate to be polished having a thickness of 1.5 mm or less using the polishing liquid of the present disclosure.

[0010] In one aspect, the present disclosure relates to a method for polishing a substrate, including polishing a substrate to be polished using the polishing liquid of the present disclosure, wherein the substrate to be polished is a substrate having a thickness of 1.5 mm or less used in the manufacture of a magnetic disk substrate.

[0011] In one aspect, the present disclosure relates to a method for improving the polishing rate of a substrate, including polishing a substrate to be polished using the polishing liquid of the present disclosure, wherein the substrate to be polished is a substrate having a thickness of 1.5 mm or less used in the manufacture of a magnetic disk substrate.

[0012] In one aspect, the present disclosure relates to a polishing liquid kit for manufacturing the polishing liquid of the present disclosure, which is one selected from the following (i) to (iii). (i) A set of a silica dispersion liquid containing component A and an aqueous medium, and an additive aqueous solution containing component B and component C (ii) A set of a silica dispersion liquid containing component A, component B and an aqueous medium, and an additive aqueous solution containing component C (iii) A set of a silica dispersion liquid containing component A, component C and an aqueous medium, and an additive aqueous solution containing component B

[0013] In one aspect, the present disclosure is a polishing liquid obtained by blending silica particles (component A), a compound represented by the following structural formula (I) (component B), a water-soluble polymer containing a constitutional unit c1 derived from a monomer having a carboxy group (component C), and an aqueous medium, Regarding the polishing liquid, when the number of moles of nitrogen atoms of component B blended in the polishing liquid is B (mol) and the number of moles of carboxy groups of component C is C (mol), the following formula (II) is satisfied. R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X···(I) In the structural formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a hydrocarbon group, R 4 is a bond or a hydrocarbon group, and X is selected from any one of a hydrogen atom, a hydroxyl group, and an amino group. R 2 and R 3 may be bonded to each other to form a cyclic structure. n is an integer of 1 or more and 15 or less. B / C < 0.8 ··· (II) [Advantages of the Invention]

[0014] According to the present disclosure, in one aspect, it is possible to provide a polishing liquid capable of improving the polishing rate without increasing scratches in a thinned substrate. [Modes for Carrying Out the Invention]

[0015] The present disclosure is based on the finding that when a polishing liquid containing silica particles, a compound represented by the structural formula (I), and a specific water-soluble polymer is used for polishing a magnetic disk substrate, for example, even in a thinned substrate having a thickness of 1.5 mm or less, the polishing rate can be improved without increasing scratches.

[0016] That is, in one aspect, the present disclosure relates to a polishing liquid containing silica particles (component A), a compound represented by the following structural formula (I) (component B), a water-soluble polymer (component C) containing a structural unit c1 derived from a monomer having a carboxy group, and an aqueous medium, and when the number of moles of nitrogen atoms of component B contained in the polishing liquid is B (mol) and the number of moles of carboxy groups of component C is C (mol), the following formula (II) is satisfied (hereinafter, also referred to as "the polishing liquid of the present disclosure"). R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X ··· (I) In the structural formula (I), R 1 , R2 and R 3 is each independently a hydrogen atom or a hydrocarbon group, and R 4 is a bond or a hydrocarbon group, and X is selected from any one of a hydrogen atom, a hydroxyl group, and an amino group. R 2 and R 3 may be bonded to each other to form a cyclic structure. n is an integer of 1 or more and 15 or less. In the present disclosure, a bond means a direct bond in which no atom or atomic group exists. When R 4 is a bond, “-R 4 -X” in formula (I) becomes “-X”. B / C < 0.8 ··· (II)

[0017] The mechanism of the expression of the effects of the present disclosure is not clear, but is presumed as follows. In the present disclosure, by using the compound (component B) represented by the structural formula (I) and a specific water-soluble polymer (component C) in combination, component B and component C interact with each other to form a complex of component B and component C. Since this complex has an adsorptivity to a polishing pad or silica particles (component A), it is considered that silica particles (component A) are held on the polishing pad via the complex, the amount of polishing liquid acting on the substrate increases, and the polishing rate is improved. In addition, it is considered that an increase in the amount of polishing liquid reduces the frequency of direct contact between the substrate and the polishing pad, reduces friction, and can prevent an increase in scratches. On the other hand, when component B is present in an excessive amount with respect to the carboxy group of component C, free component B that does not participate in complex formation is generated. Since the free component B adsorbs to the substrate surface and inhibits polishing of the substrate, it is considered that the polishing rate improvement effect is specifically exhibited when component B and component C are in a quantitative ratio that satisfies formula (II). However, the present disclosure may not be construed as being limited to these mechanisms.

[0018] In the present disclosure, a "scratch" refers to a fine scratch on the surface of a magnetic disk substrate or a substrate for a semiconductor element, with a depth of 1 nm or more and less than 100 nm, a width of 5 nm or more and less than 500 nm, and a length of 100 μm or more. Scratches on the substrate surface can be detected by an optical defect inspection device and quantitatively evaluated as the number of scratches. The number of scratches can be specifically evaluated by the method described in the examples.

[0019] [Silica particles A (Component A)] The polishing liquid of the present disclosure contains silica particles (hereinafter also referred to as "Component A") as abrasive grains. As the usage form of Component A, it is preferably in the form of a slurry in which silica particles are dispersed in an aqueous medium. Component A may be used alone or in combination of two or more.

[0020] From the viewpoint of improving the polishing rate, the D10 in terms of weight conversion by the centrifugal sedimentation method of Component A is preferably 5 nm or more, more preferably 10 nm or more, still more preferably 11 nm or more, and from the viewpoint of not increasing scratches, it is preferably 35 nm or less, more preferably 25 nm or less, still more preferably 14 nm or less. More specifically, the D10 in terms of weight conversion by the centrifugal sedimentation method of Component A is preferably 5 nm or more and 35 nm or less, more preferably 10 nm or more and 25 nm or less, still more preferably 11 nm or more and 14 nm or less.

[0021] From the viewpoint of improving the polishing rate, the D50 in terms of weight conversion by the centrifugal sedimentation method of Component A is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 17 nm or more, and from the viewpoint of not increasing scratches, it is preferably 40 nm or less, more preferably 30 nm or less, still more preferably 20 nm or less. More specifically, the D50 by the centrifugal sedimentation method of Component A is preferably 10 nm or more and 40 nm or less, more preferably 15 nm or more and 30 nm or less, still more preferably 17 nm or more and 20 nm or less.

[0022] From the perspective of not increasing scratches, the D90 in terms of weight conversion by the centrifugal sedimentation method of Component A is preferably 65 nm or less, more preferably 60 nm or less, still more preferably 55 nm or less, and even more preferably 52 nm or less. From the perspective of improving the polishing rate, it is preferably 30 nm or more, more preferably 35 nm or more, and still more preferably 40 nm or more. More specifically, the D90 in terms of weight conversion by the centrifugal sedimentation method of Component A is preferably 30 nm or more and 65 nm or less, more preferably 35 nm or more and 60 nm or less, still more preferably 40 nm or more and 55 nm or less, and even more preferably 40 nm or more and 52 nm or less.

[0023] In the present disclosure, D10, D50, and D90 in terms of weight conversion by the centrifugal sedimentation method respectively refer to the particle sizes at which the cumulative frequency from the smaller diameter side is 10%, 50%, and 90% in the particle size distribution in terms of weight conversion obtained by the centrifugal sedimentation method. In the present disclosure, the centrifugal sedimentation method is, in one or more embodiments, a method (disk centrifugal sedimentation light transmission method) of classifying and detecting particles by size according to the sedimentation velocity difference. The particle size distribution by the centrifugal sedimentation method can be measured using a disk centrifuge particle size distribution measuring device (CPS Disc Centrifuge). In the following description, the particle size distribution by the centrifugal sedimentation method may also be referred to as the "particle size distribution by CPS measurement". Specifically, it can be calculated by the measurement method described in the examples.

[0024] Examples of the method for adjusting the particle size distribution in terms of weight conversion by the centrifugal sedimentation method of Component A include, for example, methods of adjusting time, temperature, and concentration during the growth process of silica particles. Other embodiments of the method for adjusting the particle size distribution in terms of weight conversion by the centrifugal sedimentation method of Component A include, for example, a method of giving a desired particle size distribution by adding particles serving as new nuclei during the growth process of particles in its manufacturing stage, a method of mixing two or more types of silica particles having different particle size distributions to give a desired particle size distribution, and the like.

[0025] From the perspective of improving the polishing rate without increasing scratches, the average secondary particle diameter of Component A is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, even more preferably 20 nm or more. From the same perspective, it is preferably 50 nm or less, more preferably 40 nm or less, still more preferably 30 nm or less, and even more preferably 25 nm or less. More specifically, the average secondary particle diameter of Component A is preferably 1 nm or more and 50 nm or less, more preferably 5 nm or more and 40 nm or less, still more preferably 10 nm or more and 30 nm or less, and even more preferably 20 nm or more and 25 nm or less. In the present disclosure, the average secondary particle diameter of Component A means the particle diameter (D50) at which the cumulative volume ratio from the small-diameter side of the particle size distribution obtained based on the scattering intensity distribution measured by the dynamic light scattering method (DLS: Dynamic Light Scattering) is 50%. Specifically, the average secondary particle diameter of Component A in the present disclosure can be obtained by the method described in the examples.

[0026] Preferred shapes of Component A include spherical particles and mayu-shaped particles. In the present disclosure, when Component A is mayu-shaped particles, it means particles having a minimum value in the diameter in the direction perpendicular to the longitudinal direction of the particles in any of the longitudinal directions. Also, when it is spherical particles, it means particles having no minimum value in the diameter in the direction perpendicular to the longitudinal direction of the particles in any of the longitudinal directions. Among these, from the perspective of improving the polishing rate without increasing scratches, Component A is more preferably spherical particles. In the present disclosure, the proportion of the number of spherical particles in Component A is preferably more than 50%, more preferably 75% or more, still more preferably 90% or more, and even more preferably 95% or more. Examples of the method for adjusting the shape of Component A include, for example, a method of adjusting the dropping rate of the silicic acid solution, the reaction temperature, and the concentration during the growth process of the silica particles. In the present disclosure, the shape of Component A can be determined by observing the particles in one field of view with an electron microscope.

[0027] The loss on ignition of Component A on a dry mass basis (hereinafter also referred to as "LOI WL": unit = mass%) is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, still more preferably 1 mass% or more or 1.0 mass% or more, from the viewpoint of improving the polishing rate without increasing scratches, and from the same viewpoint, it is preferably 5 mass% or less, more preferably 3 mass% or less, still more preferably 2 mass% or less. More specifically, the loss on ignition WL of Component A on a dry mass basis is preferably 0.1 mass% or more and 5 mass% or less, more preferably 0.5 mass% or more and 3 mass% or less, still more preferably 1 mass% or more and 2 mass% or less or 1.0 mass% or more and 2 mass% or less.

[0028] In the present disclosure, the loss on ignition WL on a dry mass basis is, in one or more embodiments, a value calculated from the following formula by preparing a sample obtained by drying a silica slurry in which silica particles are mixed with water at a constant temperature between 105°C and 180°C, allowing it to stand and return to room temperature, and then measuring the loss on drying LOD (unit = mass%) when dried at a constant temperature between 105°C and 180°C and the loss on ignition LOI (unit = mass%) after heat-treating the sample at 800°C or higher. Specifically, it can be calculated by the method described in the examples. The smaller the loss on ignition WL on a dry mass basis, the smaller the total number of silanol groups contained in 1 g of silica particles (Component A) can be evaluated. Loss on ignition WL on a dry mass basis = 100 × {1 - (100 - LOI) / (100 - LOD)} The silanol groups of the silica particles (Component A) are considered to be the target sites where the complex formed by the compound represented by the structural formula (I) (Component B) and a specific water-soluble polymer (Component C) exhibits adsorptivity. In the present disclosure, when the value of the loss on ignition WL of Component A is within a certain range, the number of total silanol groups contained in Component A can be set in the optimal region for the expression of adsorptivity with the complex, and it is considered that the polishing rate can be improved.

[0029] As a method for adjusting the loss on ignition WL of Component A, for example, in the growth process of silica particles, methods such as adjusting the dropping rate of the silicic acid solution, the reaction temperature, and the concentration can be mentioned. As other embodiments of the method for adjusting the loss on ignition WL of Component A, for example, a method of adjusting the desired loss on ignition by subjecting existing silica particles to heat treatment, metal modification of surface silanol groups, organic acid modification, or silane coupling treatment, a method of mixing two or more types of silica particles having different losses on ignition to obtain a desired loss on ignition, and the like can be mentioned.

[0030] Examples of Component A include colloidal silica, precipitated silica, fumed silica, pulverized silica, and silica obtained by surface-modifying them. From the viewpoints of improving the polishing rate and easy availability, at least one selected from colloidal silica and precipitated silica is preferable for Component A. From the viewpoint of improving the polishing rate without increasing scratches, colloidal silica that is less likely to obtain a sharp surface shape or local surface high-hardness sites is more preferable. The colloidal silica is, for example, obtained by a method of particle growth using an aqueous alkali silicate solution as a raw material (hereinafter, also referred to as the "water glass method") and a method of condensation of a hydrolyzate of alkoxysilane (hereinafter, also referred to as the "sol-gel method"). From the viewpoints of ease of production and economy, it is preferably obtained by the water glass method. The precipitated silica is silica particles obtained by a precipitation method. Examples of the production method of precipitated silica particles include known methods such as the method described in Toray Research & Technical Report, Vol. 45 (2001), pp. 65 to 69. As a specific example of the production method of precipitated silica particles, for example, a precipitation method in which silica particles are precipitated by a neutralization reaction between a silicate such as sodium silicate and a mineral acid such as sulfuric acid can be mentioned. It is preferable to carry out the neutralization reaction under alkaline conditions at a relatively high temperature. Thereby, the growth of the primary particles of silica proceeds rapidly, and the primary particles aggregate and precipitate in a flocculent state. Preferably, by further pulverizing this, precipitated silica particles can be obtained.

[0031] From the perspective of improving the polishing rate without increasing scratches, the content of component A in the polishing liquid of the present disclosure is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, even more preferably 1.5% by mass or more, and even more preferably 3% by mass or more. From the perspective of economy, it is preferably 30% by mass or less, more preferably 20% by mass or less, still more preferably 15% by mass or less, even more preferably 10% by mass or less, and even more preferably 7% by mass or less. More specifically, the content of component A in the polishing liquid of the present disclosure is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.5% by mass or more and 20% by mass or less, still more preferably 1% by mass or more and 15% by mass or less, even more preferably 1.5% by mass or more and 10% by mass or less, and even more preferably 3% by mass or more and 7% by mass or less. When component A consists of two or more kinds of silica particles, the content of component A refers to their total content.

[0032] [Compound (Component B) Represented by Structural Formula (I)] The polishing liquid of the present disclosure contains a compound represented by the following structural formula (I) (hereinafter, also referred to as "component B"). Component B may be one kind or a combination of two or more kinds. Component B may be in the form of a salt of the compound represented by the following structural formula (I). R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X···(I)

[0033] In the above structural formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a hydrocarbon group, R 4 is a bond or a hydrocarbon group, and X is selected from any one of a hydrogen atom, a hydroxyl group, and an amino group. R 2 and R 3 may be bonded to each other to form a cyclic structure. n is an integer of 1 or more and 15 or less.

[0034] In the above structural formula (I), R 1, R 2 , and R 3 is each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms from the viewpoint of improving the polishing rate without increasing scratches. R 4 is preferably a hydrocarbon group having 1 to 4 carbon atoms from the same viewpoint. R 2 and R 3 are bonded to each other to form a cyclic structure, R 2 + R 3 is preferably a saturated or unsaturated hydrocarbon group having 2 to 4 carbon atoms, more preferably a saturated or unsaturated hydrocarbon group having 2 to 3 carbon atoms, still more preferably one selected from an ethylene group and a trimethylene group, and even more preferably an ethylene group from the viewpoint of improving the polishing rate without increasing scratches. X is more preferably one selected from a hydroxyl group and an amino group, and still more preferably a hydroxyl group from the viewpoint of improving the polishing rate without increasing scratches. n is preferably an integer of 1 or more and 10 or less, more preferably an integer of 2 or more and 5 or less, still more preferably an integer of 2 or more and 3 or less, and even more preferably 2 from the viewpoint of improving the polishing rate without increasing scratches. In the present disclosure, component B preferably has R 2 and R 3 bonded to each other to form a cyclic structure, and R 2 + R 3 is one selected from an ethylene group and a trimethylene group, and n = 2 from the viewpoint of improving the polishing rate without increasing scratches.

[0035] Component B is preferably at least one selected from ethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,2-diaminopropane, trimethylenediamine, 1,4-diaminobutane, hexamethylenediamine, N-methyltrimethylenediamine, N,N-dimethyltrimethylenediamine, N,N-diethyltrimethylenediamine, N,N-dibutyltrimethylenediamine, N,N,N',N'-tetramethyltrimethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N-ethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N-(2-hydroxyethyl)ethylenediamine (HEA), N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, diethylenetriamine, 1,4-diazacyclohexane, 2-methyl-1,4-diazacyclohexane, 2,5-dimethyl-1,4-diazacyclohexane, 1-methyl-1,4-diazacyclohexane (MDC), 1-(2-aminoethyl)-1,4-diazacyclohexane (ADC), and 1-(2-hydroxyethyl)-1,4-diazacyclohexane (HDC), and more preferably at least one selected from N-(2-hydroxyethyl)ethylenediamine (HEA), 1-methyl-1,4-diazacyclohexane (MDC), 1-(2-aminoethyl)-1,4-diazacyclohexane (ADC), and 1-(2-hydroxyethyl)-1,4-diazacyclohexane (HDC) from the viewpoint of improving the polishing rate without increasing scratches.

[0036] From the perspective of improving the polishing rate without increasing scratches, the content of component B in the polishing liquid of the present disclosure is preferably 0.001% by mass or more, more preferably 0.003% by mass or more, still more preferably 0.005% by mass or more. From the same perspective, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less, even more preferably 0.05% by mass or less, and even more preferably 0.02% by mass or less. More specifically, the content of component B in the polishing liquid of the present disclosure is preferably 0.001% by mass or more and 1% by mass or less, more preferably 0.003% by mass or more and 0.5% by mass or less, still more preferably 0.005% by mass or more and 0.1% by mass or less, even more preferably 0.005% by mass or more and 0.05% by mass or less, and even more preferably 0.005% by mass or more and 0.02% by mass or less. When component B is a combination of two or more types, the content of component B refers to their total content.

[0037] [Water-soluble polymer (component C) containing structural unit c1 derived from a monomer having a carboxy group] The polishing liquid of the present disclosure contains a water-soluble polymer (hereinafter also referred to as "component C") containing a structural unit c1 (hereinafter also simply referred to as "structural unit c1") derived from a monomer having a carboxy group. In the present disclosure, "monomer" means a compound having an ethylenically unsaturated bond. Also, in the present disclosure, "water-soluble" means having a solubility of 0.5 g / 100 mL or more, preferably 2 g / 100 mL or more, in water (20°C). Component C may be one type or a combination of two or more types. As the constitutional unit c1 derived from a monomer having a carboxy group, from the viewpoint of improving the polishing rate without increasing scratches, constitutional units derived from at least one monomer selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, and their salts can be mentioned. Among these, constitutional units derived from at least one monomer selected from acrylic acid and methacrylic acid are preferable. As the salts, alkali metal salts such as lithium, sodium, and potassium; alkaline earth metal salts such as magnesium and calcium; ammonium salts; alkanolamine salts such as triethanolamine; are preferably mentioned, and these can be used alone or in combination of two or more.

[0038] When component C is a polymer containing constitutional unit c1 and not containing constitutional component c2 described later, in one or more embodiments, component C may be a copolymer further containing a monomer other than constitutional unit c1 and constitutional unit c2 as a constitutional unit. In that case, the ratio (mol%) of constitutional unit c1 in all the constitutional units of component C is preferably more than 50 mol%, more preferably 75 mol% or more, still more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol% from the viewpoint of improving the polishing rate without increasing scratches. When component C is a polymer containing constitutional unit c1 and not containing component c2, suitable examples include one selected from polyacrylic acid, polymethacrylic acid, and their salts, and polyacrylic acid is more preferable.

[0039] In one or more embodiments, component C may further contain a constitutional unit c2 (hereinafter, also simply referred to as "constitutional unit c2") derived from a monomer having a sulfonic acid group from the viewpoint of further improving the polishing rate without increasing scratches. From the same perspective, examples of the structural unit c2 derived from a monomer having a sulfonic acid group include structural units derived from at least one monomer selected from isoprene sulfonic acid, styrene sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), 2-methacrylamido-2-methylpropane sulfonic acid, 3-allyloxy-2-hydroxypropane sulfonic acid, and salts thereof. Preferred examples of the salts include alkaline earth metal salts; ammonium salts; alkanolamine salts such as triethanolamine; and these can be used alone or in combination of two or more.

[0040] When component C is a copolymer containing structural unit c1 and structural unit c2, from the perspective of improving the polishing rate without increasing scratches, the molar ratio (c2 / c1) of the structural unit c2 derived from a monomer having a sulfonic acid group to the structural unit c1 derived from a monomer having a carboxy group in all the structural units of component C is preferably 20 or less, more preferably 10 or less, still more preferably 6 or less, even more preferably 3 or less, and even more preferably 1 or less. From the same perspective, it is preferably more than 0, more preferably 0.05 or more, still more preferably 0.1 or more, even more preferably 0.2 or more, and even more preferably 0.25 or more. More specifically, the molar ratio (c2 / c1) in all the structural units of component C is preferably more than 0 and 20 or less, more preferably 0.05 or more and 10 or less, still more preferably 0.1 or more and 6 or less, even more preferably 0.2 or more and 3 or less, and even more preferably 0.25 or more and 1 or less.

[0041] When component C is a copolymer containing structural unit c1 and structural unit c2, in one or more embodiments, component C may be a copolymer further containing a monomer other than structural unit c1 and structural unit c2 as a structural unit. In that case, from the perspective of improving the polishing rate without increasing scratches, the total ratio (mol%) of the contents of structural unit c1 and structural unit c2 in all the structural units of component C is preferably more than 50 mol%, more preferably 75 mol% or more, still more preferably 90 mol% or more, even more preferably 95 mol% or more, and even more preferably 100 mol%. When component C is a copolymer containing constitutional unit c1 and constitutional unit c2, preferred examples thereof include at least one selected from (meth)acrylic acid / isoprene sulfonic acid copolymer, (meth)acrylic acid / styrene sulfonic acid copolymer, (meth)acrylic acid / 3-allyloxy-2-hydroxypropane sulfonic acid copolymer, (meth)acrylic acid / 2-acrylamido-2-methylpropane sulfonic acid copolymer, and salts thereof, and more preferably acrylic acid / 2-acrylamido-2-methylpropane sulfonic acid copolymer. In the present disclosure, “(meth)acrylic acid” means one or more structures selected from acrylic acid and methacrylic acid. In the present disclosure, the content of each constitutional unit in all constitutional units of component C can be regarded as the ratio of the usage amount of each monomer to the total amount of monomers used in the polymerization. When component C contains other constitutional units in addition to constitutional unit c1, the sequence of each constitutional unit in component C may be random, block, or graft, but random is preferred from the viewpoints of improving the polishing rate and reducing scratches.

[0042] From the viewpoint of improving the polishing rate without increasing scratches, the weight average molecular weight of component C is preferably 2,000 or more, more preferably 3,000 or more, still more preferably 4,000 or more, even more preferably 5,000 or more, even more preferably 7,000 or more, and preferably 500,000 or less, more preferably 300,000 or less, still more preferably 200,000 or less, even more preferably 100,000 or less, even more preferably 50,000 or less. More specifically, the weight average molecular weight of component C is preferably 2,000 or more and 500,000 or less, more preferably 3,000 or more and 300,000 or less, still more preferably 4,000 or more and 200,000 or less, even more preferably 5,000 or more and 100,000 or less, even more preferably 7,000 or more and 50,000 or less. The weight average molecular weight of component C can be measured by gel permeation chromatography (GPC), and specifically can be measured by the method described in the examples.

[0043] The production method of Component C is not particularly limited, but the aqueous solution polymerization method is preferred. It can be produced by mixing and reacting each constituent unit, polymerization initiator, and chain transfer agent in a polymerization solvent. Examples of the polymerization solvent for aqueous solution polymerization include water, alcohols such as ethanol, and ketones such as acetone. These may be used alone or in combination of two or more.

[0044] In the polymerization reaction, known polymerization initiators can be used, and radical polymerization initiators are particularly preferably used. Examples of the radical polymerization initiator include persulfates such as sodium persulfate, potassium persulfate, and ammonium persulfate, hydroperoxides such as t-butyl hydroperoxide, water-soluble peroxides such as hydrogen peroxide, ketone peroxides such as methyl ethyl ketone peroxide and cyclohexanone peroxide, oil-soluble peroxides such as dialkyl peroxides such as di-t-butyl peroxide and t-butyl cumyl peroxide, and azo compounds such as azobisisobutyronitrile and 2,2-azobis(2-methylpropionamidine) dihydrochloride. From the viewpoint of the stability of the product, at least one selected from persulfates and azo compounds is preferred, and azo compounds such as azobisisobutyronitrile and 2,2'-azobis(2,4-dimethylvaleronitrile) are more preferred. These may be used alone or in combination of two or more.

[0045] In the production of Component C, a chain transfer agent may be appropriately added to the polymerization system to adjust the molecular weight. Examples of the chain transfer agent include sodium phosphite, sodium hypophosphite, potassium hypophosphite, sodium sulfite, sodium bisulfite, mercaptoacetic acid, mercaptopropionic acid, thioglycolic acid, 2-propanethiol, 2-mercaptoethanol, thiophenol, and isopropanol. From the viewpoint of the stability of the product, mercaptopropionic acid and isopropanol are more preferred. These may be used alone or in combination of two or more.

[0046] The coincidence temperature is not particularly limited, but from the viewpoint of improving reactivity, it is preferably 60°C or higher, and from the viewpoint of suppressing coloring, it is preferably 100°C or lower.

[0047] The polymerization time is not particularly limited, but from the viewpoint of improving reactivity, it is preferably 2 hours or longer, and from the viewpoint of suppressing coloring, it is preferably 20 hours or shorter.

[0048] After the polymerization reaction, neutralization can be carried out with a basic compound if necessary. Examples of the basic compound used for neutralization include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide and magnesium hydroxide, aqueous ammonia, organic amines such as monoethanolamine, diethanolamine, and triethanolamine, etc. From the viewpoint of avoiding the dispersibility of the produced water-soluble polymer compound and the contamination of the substrate to be polished, aqueous ammonia is preferred. The pH value (25°C) after neutralization is preferably 3 or higher and 10 or lower, more preferably 4 or higher and 9 or lower from the viewpoint of improving the stability of the product. Specifically, it is synthesized by the method described in the examples.

[0049] From the viewpoint of improving the polishing rate without increasing scratches, the content of component C in the polishing liquid of the present disclosure is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.03% by mass or more, and even more preferably 0.07% by mass or more. And from the same viewpoint, it is preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.2% by mass or less, and even more preferably 0.15% 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 1% by mass or less, more preferably 0.01% by mass or more and 0.5% by mass or less, still more preferably 0.03% by mass or more and 0.2% by mass or less, and even more preferably 0.07% by mass or more and 0.15% by mass or less. When component C is a combination of two or more kinds, the content of component C refers to their total content.

[0050] In the polishing liquid of the present disclosure, it is preferable that component B and component C form a complex. That is, in the polishing liquid of the present disclosure, it is preferable that component B and component C form a complex in an aqueous medium. The formation of the complex of component B and component C is preferably based on an ionic interaction acting between the nitrogen atom of component B and the carboxy group of component C.

[0051] [Molar ratio B / C of the nitrogen atom of component B and the carboxy group of component C] From the viewpoint of improving the polishing rate without increasing scratches, in the polishing liquid of the present disclosure, when the number of moles of the nitrogen atom of component B contained in the polishing liquid is B (mol) and the number of moles of the carboxy group of component C is C (mol), the following formula (II) is satisfied. Note that "the number of moles B of the nitrogen atom of component B contained in the polishing liquid" can be the number B (unit = mol) of nitrogen atoms derived from component B in the polishing liquid. "The number of moles C of the carboxy group of component C contained in the polishing liquid" can be the number C (unit = mol) of carboxy groups derived from component C in the polishing liquid. "Molar ratio B / C" can also be the ratio of the content (unit = mol / L) of nitrogen atoms derived from component B in the polishing liquid to the content (unit = mol / L) of carboxy groups derived from component C in the polishing liquid. B / C < 0.8 ··· (II)

[0052] From the viewpoint of improving the polishing rate without increasing scratches, the molar ratio B / C represented by the above formula (II) is less than 0.8, preferably 0.7 or less, more preferably 0.5 or less, still more preferably 0.4 or less, and even more preferably 0.2 or less. And from the same viewpoint, it is preferably 0.01 or more, more preferably 0.05 or more, and still more preferably 0.1 or more. More specifically, the molar ratio B / C is preferably from 0.01 or more to less than 0.8, more preferably from 0.05 or more to 0.7 or less, still more preferably from 0.1 or more to 0.5 or less, even more preferably from 0.1 or more to 0.4 or less, and even more preferably from 0.1 or more to 0.2 or less. The molar ratio B / C represented by the above formula (II) can be calculated by the method described in the examples.

[0053] [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 solvents miscible with water (for example, alcohols such as ethanol). When the aqueous medium is a mixed solvent of water and a solvent, the ratio of water to the entire mixed medium may not be particularly limited as long as the effects of the present disclosure are not hindered. From the viewpoint of economy, 95% by mass or more is preferable, 98% by mass or more is more preferable, and substantially 100% by mass is even more preferable. In the present disclosure, substantially 100% by mass means that the polishing liquid of the present disclosure is allowed to contain a very small amount of solvent components brought in as impurities from component A, component B, component C, and optional components (component D, component E, and other components) to be blended as necessary. 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 optional components (component D, component E, and other components) to be blended as necessary. From the viewpoint of improving the polishing rate, the content of the aqueous medium in the polishing liquid of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. From the same viewpoint, it is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less. From the viewpoint of improving the polishing rate, the water content in the polishing liquid of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. From the same viewpoint, it is preferably 99% by mass or less, more preferably 97% by mass or less, and even more preferably 95% by mass or less. More specifically, from the same viewpoint as above, the water content in the polishing liquid of the present disclosure is preferably 80% by mass or more and 99% by mass or less, more preferably 85% by mass or more and 97% by mass or less, and even more preferably 90% by mass or more and 95% by mass or less.

[0054] In one or more embodiments, the polishing liquid of the present disclosure preferably further contains at least one selected from acids and oxidizing agents. In one or more embodiments, the polishing liquid of the present disclosure more preferably contains both an acid and an oxidizing agent. Acids and oxidizing agents are described below.

[0055] [Acid (Component D)] From the perspective of improving the polishing rate without increasing scratches, the polishing liquid of the present disclosure preferably further contains an acid (hereinafter also referred to as "Component D"). In the present disclosure, the acid includes an acid and / or its salt. Component D may be one kind or a combination of two or more kinds. Specific examples of Component D preferably include inorganic acids such as nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, polyphosphoric acid, and amidosulfuric acid; organic acids such as organic phosphoric acid and organic phosphonic acid. Examples of salts of these acids include salts of the above acids with at least one selected from metals, ammonia, and alkylamines. Specific examples of the above metals include metals belonging to Groups 1 to 11 of the periodic table. In the present disclosure, from the perspective of improving the polishing rate without increasing scratches, as Component D, at least one selected from phosphoric acid, sulfuric acid, and 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) is preferable, at least one selected from sulfuric acid and phosphoric acid is more preferable, and phosphoric acid is even more preferable.

[0056] 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 0.001% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more from the perspective of improving the polishing rate without increasing scratches. And from the same perspective, 5% by mass or less is preferable, 4% by mass or less is more preferable, 3% by mass or less is even more preferable, and 2.5% by mass or less is still more preferable. More specifically, the content of Component D in the polishing liquid of the present disclosure is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 4% by mass or less, even more preferably 0.05% by mass or more and 3% by mass or less, and still more preferably 0.1% by mass or more and 2.5% by mass or less. When Component D is a combination of two or more kinds, the content of Component D refers to their total content.

[0057] [Oxidizing agent (Component E)] From the perspective of improving the polishing rate without increasing scratches, the polishing liquid of the present disclosure preferably further contains an oxidizing agent (hereinafter also referred to as "Component E"). Component E may be one type or a combination of two or more types. Specific examples of Component E preferably include peroxides, permanganic acid or its salts, chromic acid or its salts, peroxy acids or their salts, oxyacids or their salts, nitric acid, and sulfuric acid. In the present disclosure, as Component E, at least one selected from hydrogen peroxide, iron(III) nitrate, peracetic acid, ammonium peroxydisulfate, iron(III) sulfate, and ammonium iron(III) sulfate is preferable, and hydrogen peroxide is more preferable from the perspectives of improving the polishing rate, preventing metal ions from adhering to the surface of the substrate to be polished, and easy availability.

[0058] When the polishing liquid of the present disclosure contains Component E, the content of Component E in the polishing liquid of the present disclosure is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, from the perspective of further improving the polishing rate, and preferably 4% by mass or less, more preferably 2% by mass or less, still more preferably 1.5% by mass or less, from the perspective of improving the polishing rate without increasing scratches. More specifically, the content of Component E in the polishing liquid of the present disclosure 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, still more preferably 0.1% by mass or more and 1.5% by mass or less. When Component E is a combination of two or more types, the content of Component E refers to their total content.

[0059] [Other Components] The polishing liquid of the present disclosure may contain other components as necessary, as long as the effects of the present disclosure are not impaired. Examples of other components include amine compounds other than Component B, water-soluble polymers other than Component C, heterocyclic aromatic compounds, corrosion inhibitors, thickeners, dispersants, rust preventives, basic substances, surfactants, polishing rate improvers, and the like.

[0060] In one or more embodiments, the polishing liquid of the present disclosure can be substantially free of urea derivatives. The content of urea derivatives in the polishing liquid of the present disclosure is preferably less than 0.0001% by mass, more preferably 0.00001% by mass or less, and still more preferably 0% by mass (i.e., not contained). In one or more embodiments, the polishing liquid of the present disclosure can be substantially free of urethane softeners having a weight average molecular weight of 5,000 or less. The content of urethane softeners having a weight average molecular weight of 5,000 or less in the polishing liquid of the present disclosure is preferably less than 0.001% by mass, more preferably 0.0001% by mass or less, and still more preferably 0% by mass (i.e., not contained).

[0061] [Alumina abrasive grains] From the perspective of reducing protrusion defects, it is preferable that the polishing liquid of the present disclosure is substantially free of alumina abrasive grains. In the present disclosure, "substantially free of alumina abrasive grains" may include, in one or more embodiments, not containing alumina particles, not containing an amount of alumina particles that function as abrasive grains, or not containing an amount of alumina particles that affect the polishing result. Specifically, the content of alumina abrasive grains in the polishing liquid of the present disclosure is preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, further more preferably 0.1% by mass or less, still further more preferably 0.05% by mass or less, still further more preferably 0.02% by mass or less, and still further more preferably substantially 0% by mass (i.e., not contained), from the perspective of reducing protrusion defects in one or more embodiments. Also, the content of alumina particles in the polishing liquid of the present disclosure is preferably 2% by mass or less, more preferably 1% by mass or less, still more preferably 0.5% by mass or less, and even more preferably substantially 0% by mass (i.e., not contained) with respect to the total amount of abrasive grains in the polishing liquid in one or more embodiments.

[0062] [pH] From the perspective of improving the polishing rate without increasing scratches, the pH of the polishing liquid of the present disclosure is preferably 0.5 or more, more preferably 0.7 or more, still more preferably 0.9 or more, even more preferably 1 or more. And from the same perspective, it is preferably 9 or less, more preferably 6 or less, still more preferably 4 or less, even more preferably 3 or less, even more preferably 2.5 or less, and even more preferably 2 or less. More specifically, the pH of the polishing liquid of the present disclosure is preferably 0.5 or more and 9 or less, more preferably 0.5 or more and 6 or less, still more preferably 0.7 or more and 4 or less, even more preferably 1 or more and 3 or less, even more preferably 1 or more and 2.5 or less, and even more preferably 1 or more and 2 or less. The pH can be adjusted using the aforementioned acids or known pH adjusters. The above pH is the pH of the polishing liquid at 25°C, which can be measured using a pH meter. Preferably, it is the value after 2 minutes of immersing the electrode of the pH meter in the polishing liquid.

[0063] [Method for manufacturing the polishing liquid of the present disclosure] The polishing liquid of the present disclosure can be produced by blending component A, component B, component C, an aqueous medium, and optional components (component D, component E, and other components) as needed by a known method. Therefore, the polishing liquid of the present disclosure is, in one or more embodiments, composed of component A, component B, component C, and an aqueous medium. That is, in one or more embodiments, the present disclosure relates to a polishing liquid composed of silica particles (component A), a compound represented by the following structural formula (I) (component B), a water-soluble polymer containing a structural unit c1 derived from a monomer having a carboxy group (component C), and an aqueous medium, wherein when the number of moles of nitrogen atoms of component B incorporated in the polishing liquid is B (mol) and the number of moles of carboxy groups of component C is C (mol), it satisfies the following formula (II). R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X···(I) In the structural formula (I), R 1 , R 2 , and R 3Each is independently a hydrogen atom or a hydrocarbon group, R 4 is a bond or a hydrocarbon group, and X is selected from any one of a hydrogen atom, a hydroxyl group, and an amino group. R 2 and R 3 may be bonded to each other to form a cyclic structure. n is an integer of 1 or more and 15 or less. B / C < 0.8 ··· (II) In one aspect, the present disclosure relates to a method for producing a polishing liquid, including 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, the aqueous medium, and optional components (component D, component E, and other components) simultaneously or in any order. The blending can be performed using a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill. The preferable blending amounts of the respective components in the production method of the silica slurry and the polishing liquid can be the same as the preferable contents of the respective components in the polishing liquid according to the present disclosure described above.

[0064] In the present disclosure, the "content of each component in the polishing liquid" refers to the content of each component at the time of use, that is, at the time when the use of the polishing liquid for polishing is started. In one or more embodiments, the content of each component in the polishing liquid in the present disclosure can be regarded as the blending amount of each component.

[0065] From the viewpoints of storage and transportation, the polishing liquid of the present disclosure can be produced in the form of a concentrate and diluted at the time of use. That is, in one or more embodiments, the present disclosure relates to a concentrate for obtaining the polishing liquid of the present disclosure. From the viewpoints of production and transportation costs, the concentration ratio of the concentrate of the polishing liquid of the present disclosure is preferably 2 times or more, more preferably 10 times or more, still more preferably 30 times or more, and even more preferably 50 times or more. From the viewpoint of storage stability, it is preferably 300 times or less, more preferably 200 times or less, still more preferably 150 times or less, and even more preferably 100 times or less. The concentration ratio of the concentrate of the polishing liquid of the present disclosure means [solid content concentration of the concentrate of the polishing liquid / solid content concentration of the polishing liquid during use]. Here, the "solid content concentration of the concentrate of the polishing liquid" is the ratio of the mass of components other than water in the concentrate of the polishing liquid to the mass of the concentrate of the polishing liquid, and the "solid content concentration of the polishing liquid during use" is the ratio of the mass of components other than water in the polishing liquid during use to the mass of the polishing liquid during use. The concentrate of the polishing liquid of the present disclosure can be diluted with water so that the content of each component during use becomes the above-described content (i.e., the content of each component in the polishing liquid during use) and then used.

[0066] [Polishing Liquid Kit] In one aspect, the present disclosure is a polishing liquid kit (hereinafter, also referred to as "the polishing liquid kit of the present disclosure") for producing the polishing liquid of the present disclosure. In one or more embodiments, the polishing liquid kit of the present disclosure includes a silica dispersion (slurry) containing component A and an aqueous medium and an additive aqueous solution containing component B and component C in a state where they are not mixed with each other, and these are mixed during use and diluted with an aqueous medium as necessary to obtain the polishing liquid of the present disclosure (two-component type polishing liquid). In one or more embodiments, the polishing liquid kit of the present disclosure (i) A set of a silica dispersion containing component A and an aqueous medium and an additive aqueous solution containing component B and component C, (ii) A set of a silica dispersion containing component A, component B, and an aqueous medium and an additive aqueous solution containing component C (iii) A set of a silica dispersion containing component A, component C, and an aqueous medium and an additive aqueous solution containing component B. One selected from these is preferable. These silica dispersions and additive aqueous solutions are preferably mixed during use and diluted with an aqueous medium as necessary to obtain the polishing liquid of the present disclosure. The aqueous medium contained in the silica dispersion of the polishing liquid kit of the present disclosure may be an amount corresponding to the same amount as the polishing liquid of the present disclosure or a part thereof. The silica dispersion and the additive aqueous solution may each contain the above-described optional components (component D, component E, and other components) as necessary. According to the present disclosure, in one or more embodiments, a polishing liquid capable of improving the polishing rate without increasing scratches can be obtained from the polishing liquid kit of the present disclosure.

[0067] Generally, for a magnetic disk, a substrate to be polished that has undergone a grinding process is polished through a rough polishing process and a finish polishing process, and is manufactured through a magnetic layer forming process. The polishing liquid of the present disclosure is preferably used for polishing a magnetic disk substrate in one or more embodiments, and more preferably used for finish polishing of a magnetic disk substrate. In the present disclosure, the finish polishing refers to the polishing in the last polishing process when there are multiple polishing processes for the magnetic disk substrate. Also, in one or more embodiments, the polishing liquid of the present disclosure is preferably used for polishing a substrate to be polished with a thickness of 1.5 mm or less. In the present disclosure, the polishing liquid of the present disclosure is more preferably used for a substrate to be polished with a thickness of 1.3 mm or less, still more preferably used for a substrate to be polished with a thickness of 1.0 mm or less, and even more preferably used for a substrate to be polished with a thickness of 0.6 mm or less.

[0068] [Method for manufacturing a magnetic disk substrate] In one aspect, the present disclosure relates to a method for manufacturing a magnetic disk substrate (hereinafter, also referred to as "the substrate manufacturing method of the present disclosure") including a polishing step (hereinafter, also referred to as "the polishing step of the present disclosure") of polishing a substrate to be polished with a thickness of 1.5 mm or less using the polishing liquid of the present disclosure. The polishing step in the substrate manufacturing method of the present disclosure is preferably a finish polishing step.

[0069] [Substrate to be polished] In the substrate manufacturing method of the present disclosure, the substrate to be polished is preferably a substrate used for manufacturing a magnetic disk substrate in one or more embodiments. In one or more embodiments, a magnetic disk substrate can be manufactured by performing a step of forming a magnetic layer on the surface of the substrate by sputtering or the like after the step of polishing the surface of the substrate to be polished using the polishing liquid of the present disclosure.

[0070] Examples of the material of the substrate to be polished suitably used in the substrate manufacturing method of the present disclosure include metals or semi-metals such as silicon, aluminum, nickel, tungsten, copper, tantalum, and titanium, or alloys thereof, glassy substances such as glass, glassy carbon, and amorphous carbon, ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride, and titanium carbide, and resins such as polyimide resin. Among them, it is suitable for substrates to be polished containing metals such as aluminum, nickel, tungsten, and copper and alloys mainly composed of these metals. As the substrate to be polished, an aluminum alloy substrate plated with Ni-P, or a glass substrate such as crystallized glass, tempered glass, aluminosilicate glass, or aluminoborosilicate glass is more preferable, and an aluminum alloy substrate plated with Ni-P is even more preferable. In the present disclosure, the "aluminum alloy substrate plated with Ni-P" refers to a substrate obtained by subjecting the surface of an aluminum alloy base material to grinding and then performing electroless Ni-P plating treatment.

[0071] Examples of the shape of the substrate to be polished suitably used in the substrate manufacturing method of the present disclosure include shapes having a flat surface such as a disk shape, a plate shape, a slab shape, and a prism shape, and shapes having a curved surface such as a lens. More preferably, it is a disk-shaped substrate to be polished. In the case of a disk-shaped substrate to be polished, its outer diameter is preferably 2 to 100 mm, and its thickness is preferably 0.4 to 1.5 mm. From the viewpoint of exerting the effects of the present disclosure, the thickness of the substrate to be polished in the substrate manufacturing method of the present disclosure is preferably 1.5 mm or less, more preferably 1.2 mm or less, still more preferably 1.0 mm or less, even more preferably 0.8 mm or less, and even more preferably 0.6 mm or less.

[0072] In one or more embodiments of the polishing step in the substrate manufacturing method of the present disclosure, the polishing liquid of the present disclosure is supplied to the polishing target surface of the substrate to be polished, a polishing pad is brought into contact with the polishing target surface, and at least one of the polishing pad and the substrate to be polished is moved for polishing. In one or more embodiments, the polishing step involves sandwiching the substrate to be polished between a surface plate with a polishing pad such as a non-woven organic polymer polishing cloth attached thereto, and moving the surface plate and the substrate to be polished while supplying the polishing liquid of the present disclosure to a polishing machine to polish the substrate to be polished.

[0073] In the method for manufacturing a substrate of the present disclosure, when the polishing step of the substrate to be polished is performed in multiple stages, the polishing step using the polishing liquid of the present disclosure is preferably performed after the second stage, and more preferably performed in the final polishing step or the finishing polishing step. At that time, in order to avoid contamination of the abrasive and polishing liquid in the previous step, different polishing machines may be used respectively. When different polishing machines are used respectively, it is preferable to wash the substrate to be polished for each polishing step. Furthermore, the polishing liquid of the present disclosure can also be used in the circulating polishing for reusing the used polishing liquid. The polishing machine is not particularly limited, and a known polishing machine for substrate polishing can be used.

[0074] The polishing pad used in the present disclosure is not particularly limited. For example, a polishing pad such as a suede type, a non-woven type, a polyurethane independent foam type, or a two-layer type in which these are laminated can be used. From the viewpoint of polishing speed, a suede type polishing pad is preferable.

[0075] In the polishing step using the polishing liquid of the present disclosure, the polishing load 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 the polishing speed, and preferably 20 kPa or less, more preferably 18 kPa or less, still more preferably 16 kPa or less from the viewpoint of not increasing scratches. In the present disclosure, "polishing load" refers to the pressure of the surface plate applied to the polishing surface of the substrate to be polished during polishing. The adjustment of the polishing load can be performed by applying air pressure or a weight to at least one of the surface plate and the substrate to be polished.

[0076] In the polishing step, per 1 cm of the substrate to be polished 2The polishing amount per unit area is preferably 0.05 mg or more, more preferably 0.1 mg or more, still more preferably 0.2 mg or more, from the viewpoint of improving the polishing rate, and preferably 2.5 mg or less, more preferably 2 mg or less, still more preferably 1.6 mg or less, from the same viewpoint. More specifically, the polishing amount per 1 cm of the substrate to be polished 2 is preferably 0.05 mg or more and 2.5 mg or less, more preferably 0.1 mg or more and 2 mg or less, still more preferably 0.2 mg or more and 1.6 mg or less.

[0077] The supply rate of the polishing liquid of the present disclosure in the polishing process using the polishing liquid of the present disclosure is preferably 0.05 mL / min or more and 15 mL / min or less, more preferably 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, still more preferably 0.07 mL / min or more and 0.5 mL / min or less, per 1 cm of the substrate to be polished, from the viewpoint of ensuring the polishing rate. 2

[0078] As a method of supplying the polishing liquid of the present disclosure to the polishing machine, for example, a method of continuously supplying using a pump or the like can be mentioned. When supplying the polishing liquid to the polishing machine, in addition to the method of supplying it as a single liquid containing all the components, considering the storage stability of the polishing liquid, etc., it can also be divided into a plurality of component liquids for blending and supplied with two or more liquids. In the latter case, for example, in the supply piping or on the substrate to be polished, the plurality of component liquids for blending are mixed to form the polishing liquid of the present disclosure.

[0079] According to the substrate manufacturing method of the present disclosure, by using the polishing liquid of the present disclosure, the polishing rate can be improved.

[0080] [Polishing Method] In one aspect, the present disclosure relates to a method for polishing a substrate to be polished using the polishing liquid of the present disclosure (hereinafter, also referred to as "the polishing method of the present disclosure"), wherein the substrate to be polished is a substrate having a thickness of 1.5 mm or less used in the manufacture of a magnetic disk substrate. Examples of the substrate to be polished in the polishing method of the present disclosure include the substrate to be polished described above. The polishing method of the present disclosure is preferably used in the finish polishing process. In the polishing method of the present disclosure, from the viewpoint of exerting the effects of the present disclosure, the thickness of the substrate to be polished is preferably 1.5 mm or less, more preferably 1.2 mm or less, still more preferably 1.0 mm or less, even more preferably 0.8 mm or less, and even more preferably 0.6 mm or less. According to the polishing method of the present disclosure, by using the polishing liquid of the present disclosure, the polishing rate can be improved without increasing scratches. Therefore, the productivity of a substrate (for example, a magnetic disk substrate) with ensured substrate quality can be improved. The polishing method and conditions in the polishing method of the present disclosure can be the same as those of the substrate manufacturing method of the present disclosure described above.

[0081] [Method for improving polishing rate] In one aspect, the present disclosure relates to a method for improving the polishing rate of a substrate (hereinafter, also referred to as "the method for improving the polishing rate of the present disclosure"), which includes polishing a substrate to be polished using the polishing liquid of the present disclosure, and the substrate to be polished is a substrate with a thickness of 1.5 mm or less used in the manufacture of a magnetic disk substrate. Examples of the substrate to be polished in the method for improving the polishing rate of the present disclosure include the substrate to be polished described above. In the method for improving the polishing rate of the present disclosure, from the viewpoint of exerting the effects of the present disclosure, the thickness of the substrate to be polished is preferably 1.5 mm or less, more preferably 1.2 mm or less, still more preferably 1.0 mm or less, even more preferably 0.8 mm or less, and even more preferably 0.6 mm or less. Polishing the substrate to be polished using the polishing liquid of the present disclosure means, in one or more embodiments, supplying the polishing liquid of the present disclosure to the polishing target surface of the substrate to be polished, bringing a polishing pad into contact with the polishing target surface, and moving at least one of the polishing pad and the substrate to be polished for polishing. Alternatively, it means sandwiching the substrate to be polished between a surface plate with a polishing pad such as a non-woven organic polymer polishing cloth attached thereto, and moving the surface plate or the substrate to be polished while supplying the polishing liquid of the present disclosure to a polishing machine to polish the substrate to be polished. The polishing method and conditions in the method for improving the polishing rate of the present disclosure can be the same as those of the substrate manufacturing method of the present disclosure described above. According to the method for improving the polishing rate of the present disclosure, by using the polishing liquid of the present disclosure, it is possible to improve the polishing rate without increasing scratches.

Example

[0082] Hereinafter, the present disclosure will be described in more detail with reference to examples. However, these are illustrative and the present disclosure is not limited to these examples.

[0083] 1. Preparation of polishing liquid (Examples 1 to 18 and Comparative Examples 1 to 4) By blending component A (A1 to A2 shown in Table 2), component B (B1 to B4 shown in Tables 1 to 2), component C (C1 to C9 shown in Table 2), component D (acids shown in Table 2), component E (hydrogen peroxide), and water and stirring, the polishing liquids of Examples 1 to 18 and Comparative Examples 1 to 4 shown in Table 2 were prepared. The content (mass%, effective amount) of each component in each polishing liquid is as shown in Table 2. The content of water is the remainder obtained by subtracting component A, component B, component C, component D, and component E from the total amount of the polishing liquid (100 mass%). The pH of the polishing liquids of Examples 1 to 18 and Comparative Examples 1 to 4 was 1.5.

[0084] The following were used for component A, component B, component C, component D, and component E used in the preparation of the polishing liquid. (Component A) To 500 g of an aqueous metal silicate solution adjusted to pH 10 to 12 and a silica concentration of 2%, 7 kg of an acidic silicic acid solution adjusted to a silica concentration of 5% was intermittently dropped over 1 to 24 hours to increase the particle size (build-up). At this time, by adjusting the dropping rate, silicic acid concentration, reaction temperature, pressure, pH, etc. of the dropping solution, silica particles having a desired range of silanol groups can be obtained. In particular, by controlling the particle growth by adjusting the dropping rate, the particle shape and the amount of silanol groups, that is, the loss on ignition, can be adjusted. By the above production method, the following silica particles A1 to A2 were prepared. Component A1: Colloidal silica I (spherical particles) DLS measurement (volume conversion) average secondary particle diameter D50: 20 nm CPS measurement (weight conversion): Particle size D10: 11 nm, D50: 18 nm, D90: 44 nm Loss on ignition: 1.17 mass % Component A2: Colloidal silica II (spherical particles) DLS measurement (volume conversion): Average secondary particle size D50: 26 nm CPS measurement (weight conversion): Particle size D10: 22 nm, D50: 25 nm, D90: 58 nm Loss on ignition: 2.34 mass % (Component B) Component B1: 1-(2-Hydroxyethyl)-1,4-diazacyclohexane [HDC, manufactured by Tokyo Chemical Industry Co., Ltd.] Component B2: 1-Methyl-1,4-diazacyclohexane [MDC, manufactured by Tokyo Chemical Industry Co., Ltd.] Component B3: N-(2-Hydroxyethyl)ethylenediamine [HEA, manufactured by Tokyo Chemical Industry Co., Ltd.] Component B4: 1-(2-Aminoethyl)-1,4-diazacyclohexane [ADC, manufactured by Tokyo Chemical Industry Co., Ltd.] (Component C) The abbreviation of acrylic acid is AA, and the abbreviation of 2-acrylamido-2-methylpropanesulfonic acid is AMPS. Component C1: Copolymer of AA / AMPS = 80 / 20 (mol%) [weight average molecular weight: 9,000] (manufactured by Kao Corporation) Component C2: Copolymer of AA / AMPS = 80 / 20 (mol%) [weight average molecular weight: 30,000] (manufactured by Kao Corporation) Component C3: Copolymer of AA / AMPS = 80 / 20 (mol%) [weight average molecular weight: 100,000] (manufactured by Kao Corporation) Component C4: Copolymer of AA / AMPS = 50 / 50 (mol%) [weight average molecular weight: 10,000] (manufactured by Kao Corporation) Component C5: Copolymer of AA / AMPS = 30 / 70 (mol%) [weight average molecular weight: 8,000] (manufactured by Kao Corporation) Component C6: Polyacrylic acid [weight average molecular weight: 5,000] (manufactured by Kao Corporation) Component C7: Copolymer of AA / AMPS = 92 / 8 (mol%) [weight average molecular weight: 2,000] (manufactured by Kao Corporation) Copolymer with C8 composition: AA / AMPS = 15 / 85 (mol%) [Weight average molecular weight: 7,000] (manufactured by Kao Corporation) Copolymer with C9 composition: AA / AMPS = 5 / 95 (mol%) [Weight average molecular weight: 8,000] (manufactured by Kao Corporation) As an example of the manufacturing method, the manufacturing method of Component C1 is shown below. Prepare a 300 mL five-necked glass flask equipped with a stirring blade, thermometer, Dimroth condenser, nitrogen gas blowing tube, bubbler tube, and two dropping funnels (dropping funnels 1 and 2). Add mercaptopropionic acid (0.41 g, manufactured by Tokyo Chemical Industry Co., Ltd.), acrylic acid (25.00 g, manufactured by Tokyo Chemical Industry Co., Ltd.), 2-acrylamido-2-methylpropanesulfonic acid (18 g, manufactured by Tokyo Chemical Industry Co., Ltd.), and ethanol (28.65 g, 99.5% ethanol manufactured by Fujifilm Wako Pure Chemical Corporation) to dropping funnel 1, and add 2,2'-azobis(2,4-dimethylvaleronitrile) (0.11 g, manufactured by Fujifilm Wako Pure Chemical Corporation) and ethanol (21.43 g) to dropping funnel 2. Put ethanol (50.19 g) into the five-necked glass flask, flow nitrogen gas, flow tap water through the Dimroth condenser, and while rotating with a stirring blade, heat up to 80 °C and drop the mixtures in dropping funnels 1 and 2 at a uniform rate over 60 minutes. After dropping, stir at 80 °C for 3 hours and cool to 25 °C. Add 500 g of ethanol, drop 29% aqueous ammonia (manufactured by Kanto Chemical Co., Inc.) while stirring vigorously until the pH reaches 7.0, filter the precipitated white solid by vacuum filtration, and obtain C1 by vacuum drying. In the above example, by adjusting the amount of initiator, the amount of chain transfer agent, reaction temperature, etc., polymers (Components C2 to C9) having a molecular weight within a desired range can be obtained. For example, by reducing the amount of initiator, reducing the amount of chain transfer agent, and lowering the reaction temperature, polymers with a larger molecular weight can be obtained. (Component D) Phosphoric acid [manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, concentration 85 mass%] Sulfuric acid [manufactured by Fujifilm Wako Pure Chemical Corporation, special grade, concentration 95 mass%] HEDP (1-hydroxyethane-1,1-diphosphonic acid) [manufactured by Tokyo Chemical Industry Co., Ltd., concentration 60%] (Component E) Hydrogen peroxide [manufactured by ADEKA Corporation, concentration 35% by mass]

[0085]

Table 1

[0086] 2. Measurement methods for each parameter [Measurement method for average secondary particle size (particle size (D50) at which the cumulative volume ratio measured by dynamic light scattering method is 50%)] Component A (colloidal silica) used in the preparation of the polishing liquid was added to ion-exchanged water so that the concentration became 0.25% by mass. After that, the obtained aqueous dispersion was put into a Disposable Sizing Cuvette (polystyrene cell) up to a height of 10 mm from the bottom, and measured under the following conditions by the dynamic light scattering method using the following apparatus. The particle size (D50) at which the cumulative volume ratio from the small diameter side of the particle size distribution becomes 50% was determined and taken as the average secondary particle size of colloidal silica. The results are shown in Table 2. [Measurement conditions] Measuring instrument: Zetasizer Nano ZS [manufactured by Malvern Panalytical] Laser: He-Ne, 3.0 mW, 633 nm Scattered light detection angle: 173° Number of integrations: 20 times

[0087] [Measurement method for particle sizes D10, D50 and D90 of silica particles by centrifugal sedimentation method (CPS measurement)] Silica particles were diluted with ion-exchanged water to prepare a dispersion containing 0.4% by mass of silica particles. The prepared sample was measured for particle size distribution by centrifugal sedimentation method using the following measuring apparatus. In the particle size distribution in terms of weight conversion obtained by the centrifugal sedimentation method, the particle sizes at which the cumulative frequency from the small diameter side is 10%, 50% and 90% were taken as D10, D50 and D90, respectively. The results of D90 are shown in Table 2. [Measurement conditions] Measuring apparatus: CPS DC24000UHR [manufactured by CPS Instruments] Measurement range: 0.0004~1 μm Attenuation coefficient of particles: 0.1 Shape factor of particles: 1.0 Rotation speed: 20,000 rpm Standard particle diameter for calibration: 0.476 μm Standard particle density: 1.0465 (13%, 34 °C) Density gradient solution: Sucrose aqueous solution (8%, 24%) Viscosity of solvent: 1.16 cp (13%, 34 °C) Refractive index of solvent: 1.3592 (18%, 34 °C) Measurement temperature: 15 - 45 °C Measurement time: 100 - 420 minutes

[0088] [Loss on ignition] Silica particles were mixed with ion-exchanged water to prepare a 40% by mass silica slurry. The prepared silica slurry was adjusted to pH = 3.5 with sulfuric acid and heated at 180 °C using an infrared moisture meter "MOC63u" manufactured by Shimadzu Corporation to remove moisture. Then, it was left standing for 10 minutes and returned to room temperature to obtain 2 g of the sample. Among them, 1 g of the sample was used to determine the loss on drying LOD (reduction in moisture absorbed at room temperature: unit = mass%) again using the infrared moisture meter. The remaining 1 g of the sample was placed in a ceramic crucible and fired in a firing furnace at 1000 °C for 2 hours, and then heat was released in a desiccator for 30 minutes to determine the loss on ignition LOI (total reduction in mass due to dehydration of silanol groups and reduction in moisture absorbed at room temperature: unit = mass%). Finally, the loss on ignition based on the dry mass (unit = mass%) was determined by the following formula. The results are shown in Table 2. Loss on ignition based on dry mass = 100 × {1 - (100 - LOI) / (100 - LOD)}

[0089] [Weight-average molecular weight of water-soluble polymer (Component C)] The weight-average molecular weight of Component C was measured under the following conditions by gel permeation chromatography (GPC) method. The results are shown in Table 2. <GPC conditions> Column: TSKgel G4000PWXL + TSKgel G2500PWXL (manufactured by Tosoh Corporation) Guard column: TSKguardcolumn PWXL (manufactured by Tosoh Corporation) Eluent: 0.2 M phosphate buffer / CH 3CN = 9 / 1 (volume ratio) Temperature: 40 °C Flow rate: 1.0 mL / min Sample size: 5 mg / mL Detector: RI Standard substance: Sodium polyacrylate [Molecular weight (Mp): 115,000, 28,000, 4,100, 1,250 (manufactured by Sowa Kagaku Co., Ltd. and American Polymer Standards Corp.)]

[0090] [Molar ratio B / C of the nitrogen atom of component B and the carboxylic acid group of component C] When the structural unit c1 constituting component C consists of a monovalent acid such as acrylic acid, the molar ratio B / C of the number of moles of the nitrogen atom of component B (B: unit = mol) and the number of moles of the carboxyl group of component C (C: unit = mol) in the polishing liquid was calculated from the following formula. [Number] Here, the unit molecular weight of component C is a value obtained by weight-averaging the molecular weights of the respective structural units constituting component C according to the molar ratio of the respective structural units. For example, in component C1, it is calculated as follows. Composition of C1: AA / AMPS = 80 / 20 (mol%) Molecular weight of AA: 72.06 Molecular weight of AMPS: 207.24 Unit molecular weight of C1: 72.06 × 0.8 + 207.24 × 0.2 = 99.10

[0091] [Measurement of pH] The pH of the polishing liquid was measured at 25 °C using a pH meter (manufactured by Toa DKK Corporation), and the value after 2 minutes of immersing the electrode in the polishing liquid was adopted.

[0092] 3. Polishing of the substrate Using the prepared polishing liquids of Examples 1 to 18 and Comparative Examples 1 to 4, the following polished substrates were polished under the following polishing conditions. Subsequently, the polishing rate and the number of scratches were measured. The results are shown in Table 2.

[0093] [Substrate to be polished] As the substrates to be polished, aluminum alloy substrates S1 and S2 plated with Ni-P were used. S1 and S2 had the following dimensions respectively. S1: thickness 1.27 mm, outer diameter 95 mm, inner diameter 25 mm S2: thickness 0.6 mm, outer diameter 97 mm, inner diameter 25 mm The substrates to be polished were pre-rough-polished with a polishing liquid containing alumina abrasive so that the center line average roughness Ra measured by AFM (Digital Instrument NanoScope IIIa Multi Mode AFM) became 1 nm.

[0094] [Polishing Conditions] Polishing tester: "Double-sided 9B Polisher" manufactured by Speedfam Polishing pad: Suede type manufactured by FILWEL (foam layer: polyurethane elastomer, thickness 0.9 mm, average open pore diameter 10 μm) Polishing liquid supply rate: 100 mL / min (supply rate per 1 cm of the substrate to be polished 2 : 0.076 mL / min) Upper platen rotation speed: -16 rpm Lower platen rotation speed: 16 rpm Polishing load: 13.0 kPa Polishing time: 6 minutes Number of substrates: 10

[0095] 4. Evaluation Method [Evaluation of Polishing Rate] The mass per substrate before and after polishing was measured using an analytical balance (manufactured by Sartorius, "BP-210S"), and the mass reduction amount was obtained from the mass change of each substrate. The value obtained by dividing the average mass reduction amount of all 10 substrates by the polishing time was defined as the polishing rate and calculated by the following formula. The measurement results of the polishing rate are shown in Table 2 as relative values with the respective polishing rates when polishing the substrates to be polished S1 and S2 in Comparative Example 1 set to 100. Mass reduction amount (mg) = {mass before polishing (mg) - mass after polishing (mg)} Polishing rate (mg / min) = mass reduction amount (mg) / polishing time (min)

[0096] [Evaluation of Scratches] Measuring instrument: KLA - Tencor Corporation's "Candela OSA7100" Evaluation: Out of the substrates loaded into the polishing tester, 4 substrates were randomly selected, and each substrate was irradiated with a laser at 10,000 rpm to measure the number of scratches. The total number of scratches (pieces) on both sides of each of the 4 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 taken as 100.

[0097] 5. Results The results of each evaluation are shown in Table 2.

[0098]

Table 2

[0099] As shown in Table 2 above, it was found that the polishing liquids of Examples 1 to 18 can improve the polishing speed without increasing the scratches compared to the polishing liquids of Comparative Examples 1 to 4. Furthermore, the polishing liquids of Examples 1 to 18 effectively improved the polishing speed not only when using a 1.27 - mm - thick substrate but also when using a 0.6 - mm - thick substrate.

Industrial Applicability

[0100] According to the present disclosure, in one aspect, while reducing scratches on the surface of the polished substrate, the polishing speed can be improved, so the productivity of substrates with improved substrate quality can be improved. The present disclosure can be suitably used for the manufacture of magnetic disk substrates.

Claims

1. A polishing liquid containing silica particles (component A), a compound (component B) represented by the following structural formula (I), a water-soluble polymer (component C) containing a structural unit c1 derived from a monomer having a carboxy group, and an aqueous medium, A polishing liquid, which satisfies the following formula (II), where B (mol) is the number of moles of nitrogen atoms in component B contained in the polishing liquid, and C (mol) is the number of moles of carboxy groups in component C contained in the polishing liquid. R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X・・・(I) In the structural formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a hydrocarbon group; R 4 R is a bond or a hydrocarbon group, and X is selected from a hydrogen atom, a hydroxyl group, and an amino group. 2 and R 3 may be bonded to each other to form a cyclic structure, and n is an integer of 1 or more and 15 or less. B / C<0.8...(II)

2. 2. The polishing liquid according to claim 1, wherein component A has a particle diameter D90 of 65 nm or less, where D90 is the particle diameter at which a cumulative frequency from the small particle diameter side is 90% in a particle size distribution calculated on a weight basis obtained by a centrifugal sedimentation method.

3. 2. The polishing liquid according to claim 1, wherein component A has an ignition loss of 0.1% by mass or more and 5% by mass or less on a dry mass basis.

4. Component B is ethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,2-diaminopropane, trimethylenediamine, 1,4-diaminobutane, hexamethylenediamine, N-methyltrimethylenediamine, N,N-dimethyltrimethylenediamine, N,N-diethyltrimethylenediamine, N,N-dibutyltrimethylenediamine, N,N,N',N'-tetramethyltrimethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N-ethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N-( 2-Hydroxyethyl)ethylenediamine (HEA), N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, diethylenetriamine, 1,4-diazacyclohexane, 2-methyl-1,4-diazacyclohexane, 2,5-dimethyl-1,4-diazacyclohexane, 1-methyl-1,4-diazacyclohexane (MDC), 1-(2-aminoethyl)-1,4-diazacyclohexane (ADC), and 1-(2-hydroxyethyl)-1,4-diazacyclohexane (HDC).

5. 2. The polishing liquid according to claim 1, wherein component C is polyacrylic acid.

6. The polishing liquid according to claim 1 , wherein component C further contains a structural unit c2 derived from a monomer having a sulfonic acid group.

7. 7. The polishing liquid according to claim 6, wherein the molar ratio (c2 / c1) of the structural unit c2 derived from a monomer having a sulfonic acid group to the structural unit c1 derived from a monomer having a carboxy group, among all structural units of component C, is greater than 0 and less than or equal to 20.

8. 7. The polishing liquid according to claim 6, wherein component C is an acrylic acid / 2-acrylamide-2-methylpropanesulfonic acid copolymer.

9. The polishing liquid according to claim 1 , wherein component B and component C form a complex in the aqueous medium.

10. The polishing liquid according to claim 1 , further comprising at least one selected from the group consisting of an acid and an oxidizing agent.

11. The polishing liquid according to claim 1, which is used for finish polishing of a magnetic disk substrate.

12. 2. The polishing liquid according to claim 1, which is used for polishing a substrate having a thickness of 1.5 mm or less.

13. A method for manufacturing a magnetic disk substrate, comprising a polishing step of polishing a substrate having a thickness of 1.5 mm or less with the polishing liquid according to claim 1 .

14. The method for producing a magnetic disk substrate according to claim 13, wherein the polishing step is a finish polishing step.

15. 12. A method for polishing a substrate, comprising polishing a substrate to be polished with the polishing liquid according to claim 1, wherein the substrate to be polished is a substrate having a thickness of 1.5 mm or less that is used in the manufacture of magnetic disk substrates.

16. 12. A method for improving a polishing rate for a substrate, comprising polishing a substrate to be polished with the polishing liquid according to claim 1, wherein the substrate to be polished is a substrate having a thickness of 1.5 mm or less that is used in the manufacture of magnetic disk substrates.

17. A polishing liquid kit for producing the polishing liquid according to any one of claims 1 to 12, which is one selected from the following (i) to (iii): (i) A set of a silica dispersion containing component A and an aqueous medium, and an additive aqueous solution containing components B and C (ii) A set of a silica dispersion containing component A, component B, and an aqueous medium, and an additive aqueous solution containing component C. (iii) A set of a silica dispersion containing component A, component C, and an aqueous medium, and an additive aqueous solution containing component B

18. A polishing liquid comprising silica particles (component A), a compound (component B) represented by the following structural formula (I), a water-soluble polymer (component C) including a structural unit c1 derived from a monomer having a carboxy group, and an aqueous medium, A polishing liquid which satisfies the following formula (II), where B (mol) is the number of moles of nitrogen atoms in component B blended in the polishing liquid, and C (mol) is the number of moles of carboxy groups in component C. R 1 -N(R 2 )-(CH 2 ) n -N(R 3 )-R 4 -X・・・(I) In the structural formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a hydrocarbon group; R 4 R is a bond or a hydrocarbon group, and X is selected from a hydrogen atom, a hydroxyl group, and an amino group. 2 and R 3 may be bonded to each other to form a cyclic structure, and n is an integer of 1 or more and 15 or less. B / C<0.8...(II)

Images