WO2019216205A1

WO2019216205A1 - Polishing liquid composition for glass hard disk substrate

Info

Publication number: WO2019216205A1
Application number: PCT/JP2019/017242
Authority: WO
Inventors: 戸田勝章; 山口哲史; 多久島大樹
Original assignee: 花王株式会社
Priority date: 2018-05-10
Filing date: 2019-04-23
Publication date: 2019-11-14
Also published as: JP2019197604A; JP7158889B2

Abstract

Provided is, as one embodiment, a polishing liquid composition for a glass hard disk substrate that can prevent deterioration of surface roughness of a substrate surface after washing while maintaining the polishing rate. One embodiment of the present invention relates to a polishing liquid composition for a glass hard disk substrate that comprises abrasive grains, a sulfamic acid, a phosphate, and water.

Description

Polishing liquid composition for glass hard disk substrate

The present disclosure relates to a polishing liquid composition for a glass hard disk substrate, a method for manufacturing a glass hard disk substrate, and a method for polishing a glass substrate.

The hard disk mounted on the hard disk drive consumes high power because it rotates at high speed. In recent years, low power consumption has been demanded in consideration of the environment. In order to reduce power consumption, there is a method of increasing the recording capacity per hard disk, reducing the number of hard disks installed in the drive, and reducing the weight. In order to reduce the weight of one substrate, it is necessary to reduce the thickness of the substrate. From this point of view, the demand for a glass substrate having a higher mechanical strength than that of an aluminum substrate has increased, and the recent growth has been remarkable. . In order to improve the recording capacity per substrate, it is necessary to reduce the unit recording area. However, when the unit recording area is reduced, the magnetic signal becomes weak. Therefore, in order to improve the detection sensitivity of the magnetic signal, technological development for lowering the flying height of the magnetic head has been advanced. In the polishing of a hard disk substrate, in order to cope with the low flying height of the magnetic head, there are strict requirements for reducing surface defects and residues.

In response to such a demand, for example, Patent Document 1 proposes an acidic polishing composition containing silica particles having a specific grain diameter and a specific zeta potential.
Patent Document 2 proposes a polishing liquid composition containing (a) water, (b) a phosphate ester compound, (c) a polishing accelerator, and (d) an abrasive.
Further, Patent Document 3 proposes a polishing liquid composition containing (A) at least one selected from phosphoric acid, phosphate and phosphoric acid compound, (B) silica, and (C) water.

Japanese Unexamined Patent Publication No. 2011-704 JP 2001-89749 A Special table 2003-183630 gazette

In the polishing of the glass hard disk substrate, a method of polishing the glass substrate with an acidic polishing composition is employed. By using an acidic polishing liquid composition, there is an advantage that a leaching action in which alkali ions contained in the glass substrate are eluted during polishing occurs, the hardness of the substrate surface is lowered, and the polishing rate is improved. However, in the method of polishing a glass substrate with an acidic polishing liquid composition, since the leaching action works greatly when the pH is low, a brittle leaching layer is generated deeply, and the surface is roughened by alkali etching in the alkali cleaning step after the polishing step. There is a problem that it gets worse significantly. In general, the polishing rate and the surface roughness are in a trade-off relationship, and there is a problem that if one improves, the other deteriorates.

In one or a plurality of embodiments, the present disclosure relates to a method for manufacturing a glass hard disk substrate having a step of polishing a glass substrate with an acidic polishing liquid and a step of cleaning. Provided are a polishing composition for a glass hard disk substrate capable of suppressing deterioration of the surface roughness of the substrate, a method for producing a glass hard disk substrate using the same, and a method for polishing a glass substrate.

The present disclosure, in one aspect, relates to a polishing liquid composition for a glass hard disk substrate, which contains abrasive grains, sulfamic acid, phosphate, and water.

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

In another aspect, the present disclosure relates to a method for polishing a glass substrate, which includes polishing a glass substrate to be polished using the polishing composition of the present disclosure.

According to the present disclosure, in one or a plurality of embodiments, it is possible to suppress deterioration of the surface roughness of the glass substrate in the cleaning step while maintaining the polishing rate in the polishing step.

In the present disclosure, even when a glass substrate is polished with an acidic polishing liquid and then washed with an alkali, if the polishing liquid composition contains sulfamic acid and phosphate, the polishing rate by the acidic polishing liquid is increased. It is based on the knowledge that deterioration of the surface roughness of the glass substrate due to cleaning can be suppressed while maintaining.

That is, in one aspect, the present disclosure relates to a polishing liquid composition for glass hard disk substrate (hereinafter, also referred to as “the polishing liquid composition of the present disclosure”) containing abrasive grains, sulfamic acid, phosphate, and water. .

The mechanism of manifestation of the effect of the present disclosure is not clear, but is presumed as follows.
In general, it is known that when a glass substrate is acid-polished, metal ions are eluted from the surface of the glass substrate, the surface of the glass substrate becomes brittle and is easily polished.
In the present disclosure, it is considered that by containing sulfamic acid and phosphate in the polishing composition, elution of metal ions is promoted, and both improvement in polishing rate and suppression of deterioration of surface roughness can be achieved.
However, the present disclosure need not be construed as being limited to these mechanisms.

[Abrasive grains (component A)]
As abrasive grains (hereinafter, also referred to as “component A”) contained in the polishing composition of the present disclosure, abrasive grains generally used for polishing can be used, and metal, metal, or semimetal Carbides, nitrides, oxides, borides, diamond, and the like. The metal or metalloid element is derived from Group 2A, 2B, 3A, 3B, 4A, 4B, 5A, 6A, 7A or Group 8 of the periodic table (long period type). Specific examples of component A include silicon oxide (hereinafter referred to as silica), aluminum oxide (hereinafter referred to as alumina), silicon carbide, diamond, manganese oxide, magnesium oxide, zinc oxide, titanium oxide, cerium oxide (hereinafter referred to as ceria). ), Zirconium oxide and the like, and the use of one or more of these is preferable from the viewpoint of improving the polishing rate. Among these, from the viewpoint of suppressing the deterioration of the surface roughness while maintaining the polishing rate, the component A is preferably silica particles or ceria particles, and more preferably silica particles. Examples of the silica particles include colloidal silica, fumed silica, pulverized silica, and silica obtained by surface modification thereof, and colloidal silica is preferable. Component A may be used alone or in combination of two or more.

The silica particles are, for example, a method based on particle growth using an aqueous alkali silicate solution (hereinafter also referred to as “water glass method”) and a method based on condensation of a hydrolyzate of alkoxysilane (hereinafter referred to as “sol-gel method”). From the viewpoint of ease of production and economy, and preferably obtained by the water glass method. Silica particles obtained by the water glass method and the sol-gel method can be produced by a conventionally known method. The shape of the silica particles is not particularly limited, and may be spherical or non-spherical.

The average particle diameter of component A is preferably 1 nm or more, more preferably 5 nm or more, further preferably 10 nm or more, and 100 nm from the same viewpoint, from the viewpoint of suppressing the deterioration of the surface roughness while maintaining the polishing rate. The following is preferable, 70 nm or less is more preferable, and 40 nm or less is still more preferable. More specifically, the average particle size of component A is preferably 1 nm to 100 nm, more preferably 5 nm to 70 nm, and still more preferably 10 nm to 40 nm. The average particle diameter of component A can be determined, for example, by the method described in the examples.

The content of Component A in the polishing liquid composition of the present disclosure is preferably 0.1% by mass or more, more preferably 1% by mass or more, further preferably 3% by mass or more, from the viewpoint of improving the polishing rate. From the viewpoint of suppressing the deterioration of the surface roughness, it is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less. More specifically, the content of Component A is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 15% by mass or less. When component A is a combination of two or more, the content of component A refers to the total content thereof.

In one embodiment of the present disclosure, the content of component A, component B, component C, water, and / or other components is regarded as the blending amount of each component with respect to the total amount (100% by mass) of the polishing composition. Can do. In one or a plurality of embodiments, “content” can be read as “formulation amount”, and “containing” X can be read as “compounded”.

[Sulphamic acid (component B)]
The polishing composition of the present disclosure contains sulfamic acid (hereinafter also referred to as “component B”) from the viewpoint of suppressing the deterioration of the surface roughness while maintaining the polishing rate.

The content of Component B in the polishing composition of the present disclosure is preferably 0.05% by mass or more, more preferably 0.1% by mass or more from the viewpoint of suppressing deterioration of surface roughness while maintaining the polishing rate. Preferably, 0.15% by mass or more is more preferable, 0.3% by mass or more is more preferable, 0.5% by mass or more is more preferable, and from the same viewpoint, 10% by mass or less is preferable, and 7% by mass or less. Is more preferable, 5% by mass or less is further preferable, 4% by mass or less is further preferable, and 2% by mass or less is further preferable. More specifically, the content of Component B is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 7% by mass or less, and 0.15% by mass or more and 5% by mass or less. Is more preferably 0.15% by mass or more and 4% by mass or less, and further preferably 0.3% by mass or more and 2% by mass or less.

The mass ratio A / B (component A content / component B content) of component A and component B in the polishing liquid composition of the present disclosure suppresses deterioration of surface roughness while maintaining the polishing rate. From the viewpoint, 1 or more is preferable, 1.5 or more is more preferable, 2 or more is more preferable, and from the same viewpoint, 100 or less is preferable, 90 or less is more preferable, and 80 or less is more preferable. More specifically, the mass ratio A / B is preferably 1 or more and 100 or less, more preferably 1.5 or more and 90 or less, and still more preferably 2 or more and 80 or less.

[Phosphate (component C)]
The polishing composition of the present disclosure contains a phosphate (hereinafter also referred to as “component C”) from the viewpoint of suppressing deterioration of surface roughness while maintaining the polishing rate. Component C is not completely liberated in an aqueous medium at pH 2 (not completely H ₃ PO ₄ (aq)) from the viewpoint of suppressing the deterioration of the surface roughness while maintaining the polishing rate. The phosphate present in the form (ion) is preferred. In one or more embodiments, component C is present in salt form (ions) when added to an aqueous medium at pH 2 in the same amount as the phosphate content in the polishing composition. Is preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more with respect to the total amount (100% by mass) of Component C added to the aqueous medium having a pH of 2. For example, when the component C is sodium dihydrogen phosphate, 43% by mass of the component C added to the pH 2 aqueous medium is present in the form of salt (ion). When component C is sodium dihydrogen pyrophosphate, 96% by weight of component C added to the aqueous medium at pH 2 is present in the salt form (ions).

The phosphate of component C is preferably an alkali metal phosphate and more preferably an alkali metal hydrogen phosphate from the viewpoint of suppressing deterioration of surface roughness while maintaining the polishing rate. Specific examples of alkali metal hydrogen phosphate include dipotassium hydrogen phosphate, disodium hydrogen phosphate, diammonium hydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, pyrophosphoric acid Examples include sodium dihydrogen (sodium acid pyrophosphate), sodium pyrophosphate, sodium hexametaphosphate, sodium tripolyphosphate, and the like. Component C may be used alone or in combination of two or more.

The content of Component C in the polishing liquid composition of the present disclosure is preferably 0.3% by mass or more, more preferably 0.5% by mass or more from the viewpoint of suppressing deterioration of surface roughness while maintaining the polishing rate. Preferably, 0.8% by mass or more is more preferable, 1% by mass or more is more preferable, and from the same viewpoint, 10% by mass or less is preferable, 7% by mass or less is more preferable, and 5% by mass or less is more preferable. 3 mass% or less is still more preferable. More specifically, the content of component C is preferably 0.3% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 7% by mass or less in one or more embodiments, and 1% by mass. % To 5% by mass is more preferable, and 1% to 3% by mass is more preferable. In one or more other embodiments, the content of Component C is preferably 0.8% by mass or more and 3% by mass or less. When component C is a combination of two or more, the content of component C refers to the total content thereof.

The mass ratio A / C (content of component A / content of component C) of component A and component C in the polishing composition of the present disclosure suppresses deterioration of surface roughness while maintaining the polishing rate. From the viewpoint, 0.5 or more is preferable, 1 or more is more preferable, 1.5 or more is more preferable, and from the same viewpoint, 26 or less is preferable, 20 or less is more preferable, and 16 or less is more preferable. More specifically, the mass ratio A / C is preferably 0.5 to 26, more preferably 1 to 20, and still more preferably 1.5 to 16.

The mass ratio B / C (component B content / component C content) of component B and component C in the polishing composition of the present disclosure suppresses deterioration of surface roughness while maintaining the polishing rate. From the viewpoint, 0.01 or more is preferable, 0.03 or more is more preferable, 0.05 or more is further preferable, 0.07 or more is further preferable, 0.1 or more is further preferable, and from the same viewpoint, 50 The following is preferable, 30 or less is more preferable, 20 or less is further preferable, 10 or less is further preferable, 3 or less is further preferable, 2 or less is further preferable, 1 or less is further preferable, and 0.4 or less is further preferable. More specifically, the mass ratio B / C is preferably 0.01 or more and 50 or less, more preferably 0.01 or more and 30 or less, further preferably 0.03 or more and 20 or less, and further preferably 0.05 or more and 10 or less. 0.05 to 3 is more preferable, 0.05 to 1 is further preferable, and 0.07 to 0.4 is further preferable.

[water]
The polishing liquid composition of the present disclosure contains water as a medium. Examples of water include distilled water, ion exchange water, pure water, and ultrapure water. The content of water in the polishing liquid composition of the present disclosure can be the remainder excluding Component A, Component B, Component C, and optional components described below. Specifically, the content of water in the polishing liquid composition of the present disclosure is preferably 55% by mass or more, more preferably 70% by mass or more, and 80% by mass because the handling of the polishing liquid composition is further facilitated. % Or more, more preferably 85% by mass or more, and from the viewpoint of improving the polishing rate, 99% by mass or less is preferable, 98% by mass or less is more preferable, and 97% by mass or less is more preferable. Therefore, the water content is preferably 55% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, further preferably 80% by mass or more and 97% by mass or less, and 85% by mass or more and 97% by mass or less. The following is more preferable.

[Other ingredients]
In one or a plurality of embodiments, the polishing composition of the present disclosure may further contain other components as necessary. Examples of other components include acids other than components B and C or salts thereof, oxidizing agents, heterocyclic aromatic compounds, aliphatic amine compounds, alicyclic amine compounds, water-soluble polymers, thickeners, and dispersants. , Antirust agents, basic substances, surfactants, solubilizers, and the like. The content of the other components in the polishing liquid composition of the present disclosure is preferably 0% by mass or more, more preferably more than 0% by mass, further preferably 0.1% by mass or more, and 10% by mass or less. Preferably, 5 mass% or less is more preferable. More specifically, the content of other components is preferably 0% by mass to 10% by mass, more preferably more than 0% by mass and 10% by mass or less, and further preferably 0.1% by mass to 5% by mass. .

In one or a plurality of embodiments, the polishing liquid composition of the present disclosure may or may not include a phosphate ester compound.
In one or a plurality of embodiments, the polishing liquid composition of the present disclosure may be a polishing liquid composition composed of Component A, Component B, Component C, and water.

[PH of polishing composition]
The pH of the polishing composition of the present disclosure is preferably 0.9 or more, more preferably 1 or more, still more preferably 1.5 or more, from the viewpoint of suppressing deterioration of surface roughness while maintaining the polishing rate. From the same viewpoint, 6 or less is preferable, 5 or less is more preferable, and 4.5 or less is more preferable. More specifically, the pH of the polishing composition of the present disclosure is preferably 0.9 or more, 6 or less, more preferably 1 or more and 5 or less, further preferably 1 or more and 4.5 or less, and 1.5 or more and 4. 5 or less is more preferable. The pH can be adjusted using the above-described Component B and Component C, a known pH adjusting agent, or the like. In the present disclosure, the pH is the pH of the polishing composition at 25 ° C. and can be measured using a pH meter. For example, the pH meter electrode is immersed in the polishing composition and the value is 2 minutes later. be able to.

[Method for producing polishing composition]
In one or a plurality of embodiments, the polishing liquid composition of the present disclosure may be a polishing liquid composition for a glass hard disk substrate formed by blending Component A, Component B, Component C and water. For example, the polishing composition of the present disclosure can be produced by blending Component A, Component B, Component C, and water, and, if desired, other components by a known method. That is, in another aspect, the present disclosure includes a method for producing a polishing liquid composition (hereinafter referred to as “a method for producing a polishing liquid composition of the present disclosure”, which includes a step of blending at least component A, component B, component C and water. "). In the present disclosure, “mixing” includes mixing component A, component B, component C and water, and optionally other components simultaneously or in any order. The abrasive grains of component A may be mixed in a concentrated slurry state, or may be mixed after being diluted with water or the like. When component A is composed of a plurality of types of abrasive grains, the plurality of types of abrasive grains can be blended simultaneously or separately. When component C consists of a plurality of types of phosphates, the plurality of types of phosphates can be blended simultaneously or separately. The said mixing | blending can be performed using mixers, such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill, for example. The preferable compounding amount of each component in the manufacturing method of the polishing liquid composition of the present disclosure can be the same as the preferable content of each component in the polishing liquid composition of the present disclosure described above.

In the present disclosure, the “content of each component in the polishing liquid composition” means the content of each component at the time of use, that is, when the polishing liquid composition starts to be used for polishing. The polishing composition of the present disclosure may be stored and supplied in a concentrated state as long as its storage stability is not impaired. In this case, it is preferable in that the manufacturing and transportation costs can be further reduced. The concentrate of the polishing liquid composition of the present disclosure may be used by appropriately diluting with the above-described water as necessary at the time of use. The dilution rate is not particularly limited as long as the content (in use) of each component described above can be secured after dilution, and can be, for example, 10 to 100 times.

[Polishing liquid kit]
In another aspect, the present disclosure relates to a kit for producing the polishing liquid composition of the present disclosure (hereinafter, also referred to as “polishing liquid kit of the present disclosure”). As one embodiment of the polishing liquid kit of the present disclosure, for example, a polishing liquid containing an abrasive dispersion liquid containing component A and water and an aqueous additive solution containing component B and component C are not mixed with each other. A kit (two-pack type polishing composition) can be mentioned. The abrasive dispersion and the additive aqueous solution are mixed at the time of use, and diluted with water as necessary. The abrasive dispersion and the additive aqueous solution may further contain other components as described above, if necessary. According to the polishing liquid kit of the present disclosure, it is possible to obtain a polishing liquid composition that can suppress the deterioration of the surface roughness after cleaning while maintaining the polishing rate.

[Polished glass substrate]
The glass substrate to be polished by using the polishing composition of the present disclosure is a glass substrate used in the manufacturing process of a glass hard disk substrate in one or a plurality of embodiments. Examples of the material of the glass substrate include quartz glass, soda lime glass, aluminosilicate glass, borosilicate glass, aluminoborosilicate glass, alkali-free glass, and crystallized glass. In one or a plurality of embodiments, the polishing composition of the present disclosure is suitably used for polishing an aluminosilicate glass substrate or an aluminoborosilicate glass substrate. In one or a plurality of embodiments, the glass substrate to be polished according to the present disclosure can be used as any of a horizontal magnetic recording substrate, a perpendicular magnetic recording substrate, and a thermally assisted recording (HAMR) substrate.

Examples of the shape of the glass substrate to be polished include a shape having a flat portion such as a disk shape, a plate shape, a slab shape, and a prism shape, and a shape having a curved surface portion such as a lens. Of these, a disk-shaped glass substrate to be polished is suitable. In the case of a disk-shaped polished glass substrate, the outer diameter is, for example, about 2 mm to 100 mm, and the thickness is, for example, about 0.4 mm to 2 mm.

[Glass hard disk substrate manufacturing method]
In general, a glass hard disk substrate is obtained from a process of obtaining a glass substrate by a mold press of molten glass or a method of cutting out from sheet glass, a shape processing process, an end surface polishing process, a rough grinding process, a fine grinding process, a rough polishing process, and a finish polishing. It is manufactured through a process and a chemical strengthening process. The chemical strengthening step may be performed before the finish polishing step. In addition, a cleaning process may be included between the processes. The glass hard disk substrate after the polishing process becomes a glass hard disk substrate formed into a magnetic disk through a recording portion forming process including the formation of a magnetic film. The polishing composition of the present disclosure is preferably used for polishing (finish polishing) in the final polishing step.

Therefore, in another aspect, the present disclosure includes a step of polishing a glass substrate to be polished using the polishing liquid composition of the present disclosure (hereinafter, also referred to as “polishing step using the polishing liquid composition of the present disclosure”). And a glass hard disk substrate manufacturing method (hereinafter also referred to as “substrate manufacturing method of the present disclosure”). According to the substrate manufacturing method of the present disclosure, by using the polishing composition in the present disclosure, an effect that a high-quality magnetic disk substrate can be manufactured with high yield and high productivity can be achieved.

(Polishing process)
In one or a plurality of embodiments, the polishing step using the polishing liquid composition of the present disclosure is performed by supplying the polishing liquid composition of the present disclosure to the polishing target surface of the glass substrate to be polished, and providing the polishing pad on the polishing target surface. In this step, polishing is performed by moving at least one of the polishing pad and the substrate to be polished while applying contact and applying a predetermined pressure (load). Further, in one or a plurality of other embodiments, the polishing step using the polishing liquid composition of the present disclosure is performed by using a surface plate to which a polishing pad such as a non-woven organic polymer polishing cloth is attached. It is a step of polishing the substrate to be polished by moving the surface plate or the substrate to be polished while sandwiching and supplying the polishing composition of the present disclosure to the polishing machine.

When the polishing process of the substrate to be polished is performed in multiple stages, the polishing process using the polishing composition of the present disclosure is preferably performed in the second stage or later, and is performed in the final polishing process or the final polishing process. Is more preferable. At that time, in order to avoid mixing of the polishing material and polishing liquid composition in the previous process, different polishing machines may be used, and in the case of using different polishing machines, polishing is performed for each polishing process. It is preferable to clean the substrate. Furthermore, the polishing composition of the present disclosure can also be used in cyclic polishing in which the used polishing liquid is reused. The polishing machine is not particularly limited, and a known polishing machine for substrate polishing can be used.

There is no restriction | limiting in particular as a polishing pad used by the grinding | polishing process using the polishing liquid composition of this indication, For example, polishing of a suede type, a nonwoven fabric type, a polyurethane independent foam type, or the two-layer type which laminated | stacked these etc. A pad can be used, and a suede type polishing pad is preferable from the viewpoint of polishing rate.

The average pore diameter of the surface member of the polishing pad is preferably 50 μm or less, more preferably 45 μm or less, still more preferably 40 μm or less, further preferably 35 μm or less, from the viewpoint of improving the polishing rate and the pad life, and the pad polishing liquid From the viewpoint of retention, 0.01 μm or more is preferable, 0.1 μm or more is more preferable, 1 μm or more is further preferable, and 10 μm or more is more preferable. More specifically, the average opening diameter of the surface member of the polishing pad is preferably 0.01 μm or more and 50 μm or less, more preferably 0.1 μm or more and 45 μm or less, further preferably 1 μm or more and 40 μm or less, and further preferably 10 μm or more and 35 μm or less. preferable. The maximum value of the opening diameter of the polishing pad is preferably 100 μm or less, more preferably 70 μm or less, still more preferably 60 μm or less, and even more preferably 50 μm or less from the viewpoint of maintaining the polishing rate.

The polishing load in the polishing step using the polishing liquid composition of the present disclosure is preferably 3 kPa or more, more preferably 4 kPa or more from the viewpoint of improving the polishing rate, and stable so that no vibration is generated in the polishing machine during polishing. From the viewpoint of being able to be polished, it is preferably 40 kPa or less, and more preferably 15 kPa or less. More specifically, the polishing load is preferably 3 kPa or more and 40 kPa or less, and more preferably 4 kPa or more and 15 kPa or less. In the present disclosure, the polishing load refers to the pressure of the surface plate applied to the polishing surface of the substrate to be polished during polishing. The polishing load can be adjusted by applying air pressure or weight to at least one of the surface plate and the substrate to be polished.

In the polishing process using the polishing composition of the present disclosure, the supply rate of the polishing composition of the present disclosure is 0.01 mL / min or more per 1 cm ^{2 of the} substrate to be polished from the viewpoint of cost reduction and polishing rate improvement. / Min or less is preferable, 0.025 mL / min or more and 0.6 mL / min or less is more preferable, 0.05 mL / min or more and 0.4 mL / min or less is more preferable, 0.1 mL / min or more and 0.4 mL / min or less. Is even more preferred. In addition, since the polishing composition can be reused in the case of cyclic polishing, the supply flow rate may be higher than the flow rate described above.

Examples of a method of supplying the polishing composition of the present disclosure to a polishing machine include a method of continuously supplying using a pump or the like. When supplying the polishing composition to the polishing machine, in addition to the method of supplying one component containing all the components, considering the stability of the polishing composition, etc., it is divided into a plurality of compounding component liquids, Two or more liquids can be supplied. In the latter case, for example, the plurality of compounding component liquids are mixed in the supply pipe or on the substrate to be polished to obtain the polishing liquid composition of the present disclosure.

(Washing process)
In one or a plurality of embodiments, the substrate manufacturing method of the present disclosure is a method of cleaning a glass substrate (substrate to be cleaned) that has been polished using the polishing liquid composition of the present disclosure, using the cleaning composition described above. Step (hereinafter also referred to as “cleaning step”). The substrate to be cleaned in the cleaning process includes a glass substrate immediately after the polishing process using the polishing composition of the present disclosure, a dipping process in water to prevent drying after the polishing process, a water cleaning process as preliminary cleaning, A glass substrate that has undergone an acid cleaning step or the like is included. In one or a plurality of embodiments, this cleaning step includes (a) immersing the substrate to be cleaned in the cleaning composition, and / or (b) injecting the cleaning composition on the surface of the substrate to be cleaned. Is performed by supplying a cleaning composition to

In the method (a), the conditions for immersing the substrate to be cleaned in the cleaning composition may not be particularly limited. For example, the temperature of the cleaning composition is 20 ° C. or more and 100 ° C. or less from the viewpoint of safety and operability, and the immersion time is 10 seconds or more from the viewpoint of cleaning performance and production efficiency by the cleaning composition. Within 60 minutes. From the viewpoint of improving the removability of the residue and the dispersibility of the residue, it is preferable that ultrasonic vibration is applied to the cleaning composition. Examples of the ultrasonic frequency include 20 kHz to 2000 kHz.

In the method (b), from the viewpoint of promoting the cleaning property of the residue and the solubility of the oil, the cleaning agent composition to which ultrasonic vibration is applied is injected to the cleaning substrate surface. The surface is contacted to clean the surface, or the cleaning composition is supplied by injection onto the surface of the substrate to be cleaned and then cleaned by rubbing the surface supplied with the cleaning composition with a cleaning brush. It is preferable to do. Furthermore, the cleaning composition to which ultrasonic vibration is applied is supplied to the surface to be cleaned by injection, and the surface to which the cleaning composition is supplied is cleaned by rubbing with a cleaning brush. Is preferred.

As means for supplying the cleaning composition onto the surface of the substrate to be cleaned, known means such as a spray nozzle can be used. Examples of the cleaning brush include known brushes such as a nylon brush and a PVA (polyvinyl alcohol) sponge brush. The ultrasonic frequency may be the same as the value preferably adopted in the method (a).

In addition to the method (a) and / or the method (b), the cleaning step may include one or more steps using known cleaning such as rocking cleaning, cleaning using rotation of a spinner, paddle cleaning, and the like. Good.

As the cleaning composition used in the cleaning process, for example, an alkaline agent, water, and various additives as required can be used. As the alkali agent, at least one of an inorganic alkali agent and an organic alkali agent can be used. Examples of the inorganic alkaline agent include ammonia, potassium hydroxide, and sodium hydroxide. Examples of the organic alkali agent include at least one selected from hydroxyalkylamine, tetramethylammonium hydroxide, and choline. Examples of various additives include nonionic surfactants, chelating agents, ether carboxylates, fatty acids, anionic surfactants, water-soluble polymers, antifoaming agents, alcohols, preservatives, antioxidants, and the like. It is done.

The pH of the cleaning composition used in the cleaning step is preferably 8 or more and 13 or less, for example, from the viewpoint of improving the dispersibility of the residue on the substrate. The above pH is the pH of the cleaning composition at 25 ° C. and can be measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G). For example, the electrode is immersed in the cleaning composition for 3 minutes. Later numbers can be adopted.

(Magnetic film formation process)
In one or a plurality of embodiments, a substrate manufacturing method of the present disclosure includes a step of forming a magnetic film on a glass substrate after a polishing step and a cleaning step of a glass substrate to be polished, or a recording unit formation including formation of a magnetic film You may have a process.

[Glass substrate polishing method]
As another aspect, the present disclosure relates to a glass substrate polishing method (hereinafter, also referred to as “polishing method of the present disclosure”) including polishing a glass substrate to be polished using the polishing composition of the present disclosure. By using the polishing method of the present disclosure, an effect that a high-quality magnetic disk substrate can be manufactured with high yield and high productivity can be achieved. Examples of the glass substrate to be polished in the polishing method of the present disclosure include those used for manufacturing a glass hard disk substrate as described above. Specific polishing methods and conditions may be the same methods and conditions as the above-described substrate manufacturing method of the present disclosure.

Polishing a glass substrate to be polished using the polishing liquid composition of the present disclosure includes supplying the polishing liquid composition of the present disclosure to the surface to be polished of the substrate to be polished in one or a plurality of embodiments. A polishing pad is brought into contact with the surface, and polishing is performed by moving at least one of the polishing pad and the substrate to be polished, or a surface plate on which a polishing pad such as a non-woven organic polymer polishing cloth is attached. The substrate to be polished is sandwiched and the surface plate or the substrate to be polished is moved to polish the substrate to be polished while supplying the polishing composition of the present disclosure to the polishing machine.

The present disclosure further relates to one or more of the following embodiments.
<1> A polishing liquid composition for a glass hard disk substrate, comprising abrasive grains (component A), sulfamic acid (component B), phosphate (component C), and water.

<2> The polishing composition according to <1>, wherein component A is silica particles.
<3> The polishing composition according to <1>, wherein component A is colloidal silica.
<4> The polishing liquid according to any one of <1> to <3>, wherein the content of component A is preferably 0.1% by mass or more, more preferably 1% by mass or more, and further preferably 3% by mass or more. Composition.
<5> The content of component A is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less, and the polishing composition according to any one of <1> to <4> .
<6> The polishing liquid according to any one of <1> to <5>, wherein the content of component A is preferably 0.1% by mass or more and 20% by mass or less, more preferably 1% by mass or more and 15% by mass or less. Composition.
<7> The content of component B is preferably 0.05% by mass or more, more preferably 0.1% by mass or more, further preferably 0.15% by mass or more, further preferably 0.3% by mass or more, 0 The polishing composition according to any one of <1> to <6>, further preferably 5% by mass or more.
<8> The content of Component B is preferably 10% by mass or less, more preferably 7% by mass or less, further preferably 5% by mass or less, further preferably 4% by mass or less, and further preferably 2% by mass or less. Polishing liquid composition in any one of <1> to <7>.
<9> The content of Component B is preferably 0.05% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 7% by mass or less, and further preferably 0.15% by mass or more and 5% by mass or less. The polishing composition according to any one of <1> to <8>, more preferably 0.3% by mass to 4% by mass, and further preferably 0.5% by mass to 2% by mass.
<10> The polishing according to any one of <1> to <9>, wherein the mass ratio A / B between component A and component B is preferably 1 or more, more preferably 1.5 or more, and still more preferably 2 or more. Liquid composition.
<11> The polishing liquid composition according to any one of <1> to <10>, wherein the mass ratio A / B between component A and component B is preferably 100 or less, more preferably 90 or less, and still more preferably 80 or less. object.
<12> The mass ratio A / B between the component A and the component B is preferably 1 or more and 100 or less, more preferably 1.5 or more and 90 or less, and further preferably 2 or more and 80 or less, from <1> to <11> The polishing liquid composition in any one.
<13> When component C is added to an aqueous medium at pH 2 in the same amount as the phosphate content in the polishing composition, the proportion of component C present in the form of a salt is aqueous at pH 2. <1> to <12>, preferably 10% by mass or more, more preferably 20% by mass or more, and still more preferably 30% by mass or more, based on the total amount of component C added to the medium. Polishing liquid composition.
<14> Component C is dipotassium hydrogen phosphate, disodium hydrogen phosphate, diammonium hydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen pyrophosphate, pyrroline Polishing liquid composition in any one of <1> to <13> which is 1 type, or 2 or more types chosen from sodium acid, sodium hexametaphosphate, and sodium tripolyphosphate.
<15> The content of component C is preferably 0.3% by mass or more, more preferably 0.5% by mass or more, further preferably 0.8% by mass or more, and further preferably 1% by mass or more. <1> To <14>.
<16> The content of component C is preferably 10% by mass or less, more preferably 7% by mass or less, further preferably 5% by mass or less, and further preferably 3% by mass or less, any one of <1> to <15> A polishing liquid composition according to claim 1.
<17> The content of component C is preferably 0.3% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 7% by mass or less, and further preferably 1% by mass or more and 5% by mass or less. The polishing composition according to any one of <1> to <16>, wherein the content is more preferably no less than 3% by mass and no more than 3% by mass.
<18> The polishing composition according to any one of <1> to <16>, wherein the content of component C is 0.8% by mass or more and 3% by mass or less.
<19> The mass ratio A / C between the component A and the component C is preferably 0.5 or more, more preferably 1 or more, and further preferably 1.5 or more, according to any one of <1> to <18>. Polishing liquid composition.
<20> The polishing liquid composition according to any one of <1> to <19>, wherein the mass ratio A / C between component A and component C is preferably 26 or less, more preferably 20 or less, and still more preferably 16 or less. object.
<21> The mass ratio A / C between the component A and the component C is preferably 0.5 or more and 26 or less, more preferably 1 or more and 20 or less, and further preferably 1.5 or more and 16 or less, <1> to <20 > The polishing liquid composition in any one of>.
<22> The mass ratio B / C between the component B and the component C is preferably 0.01 or more, more preferably 0.03 or more, still more preferably 0.05 or more, still more preferably 0.07 or more, and 1 or more, The polishing liquid composition in any one of <1> to <21>.
<23> The mass ratio B / C between the component B and the component C is preferably 50 or less, more preferably 30 or less, still more preferably 20 or less, still more preferably 10 or less, still more preferably 3 or less, and even more preferably 2 or less. The polishing composition according to any one of <1> to <22>, preferably 1 or less, more preferably 0.4 or less.
<24> The mass ratio B / C between the component B and the component C is preferably 0.01 or more and 50 or less, more preferably 0.01 or more and 30 or less, further preferably 0.03 or more and 20 or less, and 0.05 or more. 10 or less is more preferable, 0.05 or more and 3 or less is more preferable, 0.05 or more and 1 or less is more preferable, and 0.07 or more and 0.4 or less is further preferable, <1> to <23> Polishing liquid composition.
<25> The polishing composition according to any one of <1> to <24>, which does not contain a phosphate ester compound.
<26> The polishing composition according to any one of <1> to <25>, comprising Component A, Component B, Component C, and water.
<27> The polishing composition according to any one of <1> to <26>, wherein the pH is preferably 0.9 or more, more preferably 1 or more, and still more preferably 1.5 or more.
<28> The polishing composition according to any one of <1> to <27>, wherein the pH is preferably 6 or less, more preferably 5 or less, and even more preferably 4.5 or less.
<29> The pH is preferably 0.9 or more and 6 or less, more preferably 1 or more and 5 or less, further preferably 1 or more and 4.5 or less, and further preferably 1.5 or more and 4.5 or less, from <1> to <28> The polishing liquid composition according to any one of the above.
<30> The polishing composition according to any one of <1> to <29>, wherein the glass hard disk substrate is an aluminoborosilicate glass substrate.
<31> A method for producing a glass hard disk substrate, comprising a step of polishing a glass substrate to be polished using the polishing composition according to any one of <1> to <30>.
<32> A method for polishing a glass substrate, comprising polishing a glass substrate to be polished using the polishing composition according to any one of <1> to <30>.

Hereinafter, the present disclosure will be described in more detail by way of examples. However, these examples are illustrative, and the present disclosure is not limited to these examples.

1. Preparation of polishing liquid compositions (Examples 1 to 10 and Comparative Examples 1 to 7)
Table 1 shows component A (colloidal silica, average particle size 20 nm), component B (sulfamic acid) or non-component B (acid shown in Table 1), component C (phosphate shown in Table 1) and ion-exchanged water. The polishing liquid compositions of Examples 1 to 10 and Comparative Examples 1 to 7 were prepared by blending at the stated ratio (mass%) and stirring.

In the preparation of the polishing composition shown in Table 1, the following were used for Component B, Non-Component B, and Component C.
Sulfamic acid [manufactured by Sun Chemical Co., Ltd.] (component B)
Sulfuric acid [Wako Pure Chemical Industries, Ltd.] (non-component B)
Phosphoric acid [Wako Pure Chemical Industries, Ltd.] (non-component B)
Citric acid [Made by Iwata Chemical Industry] (non-component B)
Tartaric acid [Wako Pure Chemical Industries, Ltd.] (non-component B)
Acid soda pyrophosphate [disodium dihydrogen pyrophosphate, manufactured by Phosphor Chemical Industries Ltd.] (component C)
Potassium dihydrogen phosphate [Wako Pure Chemical Industries, Ltd.] (Component C)
Sodium sulfate [Wako Pure Chemical Industries, Ltd.] (non-component C)
Here, when sodium acid pyrophosphate (component C) is added to an aqueous medium having a pH of 2 in the same amount as the content of sodium acid pyrophosphate in the polishing composition (content described in Table 1), The proportion of sodium acid pyrophosphate present in the form of a salt is 96% by weight, based on the total amount of sodium acid pyrophosphate added in the aqueous medium at pH 2.
When potassium dihydrogen phosphate (component C) is added to an aqueous medium at pH 2 in the same amount as the content (1.2% by mass) of potassium dihydrogen phosphate in the polishing composition, it is in the form of a salt. The proportion of potassium dihydrogen phosphate present in is 43% by weight, based on the total amount of potassium dihydrogen phosphate added to the aqueous medium at pH.

2. Measuring method of various parameters [Measuring method of average particle diameter of silica particles (component A)]
A sample containing colloidal silica particles was observed with a transmission electron microscope “JEM-2000FX” (80 kV, 1 to 50,000 times, manufactured by JEOL Ltd.) according to the instructions attached by the manufacturer, and TEM (Transmission Electron) was observed. Microscope) images were taken. This photograph was taken into a personal computer as image data by a scanner, and the equivalent diameter of each silica particle was measured using analysis software “WinROOF ver. 3.6” (distributor: Mitani Corp.) to obtain the particle diameter. . Thus, after calculating | requiring the particle diameter of 1000 silica particles, these average values were computed and this average value was made into the average particle diameter.

[Method for measuring pH of polishing composition]
The pH of the polishing composition was measured at 25 ° C. using a pH meter (manufactured by Toa DKK Co.), and the value after 2 minutes after the electrode was immersed in the polishing composition was adopted. The measurement results are shown in Table 1.

3. Preparation of substrate to be polished An aluminoborosilicate glass substrate roughly polished in advance with a polishing composition containing ceria abrasive grains was prepared as a substrate to be polished. Constituent elements contained in the substrate had a Si content of 24% by mass, an Al content of 8% by mass, and a B content of 1% by mass. The constituent elements were measured using the ESCA (Electron Spectroscopy for Chemical Analysis) method under the following measurement conditions.
<ESCA measurement conditions>
(1) Sample preparation An aluminoborosilicate glass substrate was cut into 1 cm x 1 cm and placed on a carbon double-sided tape and fixed. In order to remove dust on the surface, Ar sputtering was performed for 6 minutes at an acceleration voltage of 2 kV, and ESCA measurement was performed.
(2) Measurement condition equipment: PHI Quantera SXM manufactured by ULVAC-PHI
X-ray source: Monochromatic AlKα ray, 1486.6 eV, 25 W, 15 kV
Beam diameter: 100 μm
X-ray incident angle: 45 °
Measurement range: 1000 × 1000 (μm ² )
Pass energy: 280.0 (survey), 112.0 eV (narrow)
Step size: 1.00 (survey), 0.200 eV (narrow)
Measurement elements: C, O, Mg, Al, Si, Ca, Sr, Sn, Ba
Charging correction: Neutralizer and Ar ⁺ irradiation

4). Polishing Method The substrate to be polished was polished using the polishing liquid compositions of Examples 1 to 10 and Comparative Examples 1 to 7 under the following polishing conditions.

[Polishing conditions]
Polishing tester: "Fast double-sided 9B polishing machine" manufactured by Speedfam
Polishing pad: Suede type (thickness 0.9mm, average pore diameter 30μm, material: urethane foam)
Polishing liquid composition supply amount: 100 mL / min (supply rate per 1 cm ^{2 of} polishing substrate: about 0.3 mL / min)
Lower platen rotation speed: 24rpm
Polishing load: 4.9 kPa
Carrier: Aramid, thickness 0.5mm
Polishing time: 30 minutes Substrate to be polished: Aluminoborosilicate glass substrate (outer diameter 95 mm, inner diameter 25 mm, thickness 0.65 mm)
Number of input substrates: 5

5). Evaluation [Evaluation of polishing rate]
The weight per substrate before and after polishing was measured (measured by Sartorius, “BP-210S”), and the amount of mass loss was determined from the change in mass of each substrate. A value obtained by dividing the average mass reduction amount of all five sheets by the polishing time was defined as a polishing rate, and was calculated by the following formula. The measurement results of the polishing rates of Examples 1 to 10 and Comparative Examples 1 and 3 to 7 are shown in Table 1 below as relative values with Comparative Example 2 taken as 100.
Weight loss (g) = {mass before polishing (g) −mass after polishing (g)}
Polishing rate (mg / min) = mass reduction amount (mg) / polishing time (min)

[Evaluation of surface roughness]
The polished substrate is immersed for 1 hour in a bath containing a pH 12 alkaline detergent composition (temperature: 25 ° C.) made of 20 ppm KOH aqueous solution. The substrate after the immersion is rinsed with ion exchange water for 60 seconds, and then the substrate surface is completely dried. Then, the surface roughness of both surfaces of each substrate was measured using AFM (Bruker Dimension Icon) under the following measurement conditions, and the average value was calculated. The results of surface roughness (AFM-Ra) are shown in Table 1 as relative values with Comparative Example 2 taken as 100.
<AFM measurement conditions>
Mode: Tapping mode
Area: 1 × 1μm
Scan rate: 1.0 Hz
Cantilever: OTESPA-R3
Line: 256 × 256

As shown in Table 1 above, the polishing liquid compositions of Examples 1 to 10 were deteriorated in the surface roughness of the substrate after cleaning while maintaining the polishing rate as compared with the polishing liquid compositions of Comparative Examples 1 to 7. Was suppressed.

According to the polishing composition of the present disclosure, deterioration of the surface roughness of the substrate surface after cleaning can be suppressed while maintaining the polishing rate. Therefore, the polishing composition of the present disclosure is useful in the production of various glass substrates, and is particularly useful in the production of glass substrates for hard disks.

Claims

Polishing liquid composition for glass hard disk substrate containing abrasive grains, sulfamic acid, phosphate, and water.
The polishing composition according to claim 1, wherein the pH is 0.9 or more and 6 or less.
The polishing composition according to claim 1 or 2, wherein the abrasive grains are silica particles.
The polishing composition according to claim 1 or 2, wherein the abrasive grains are colloidal silica.
The polishing composition according to any one of claims 1 to 4, wherein the content of sulfamic acid in the polishing composition is 0.05% by mass or more and 10% by mass or less.
The polishing composition according to any one of claims 1 to 4, wherein the content of sulfamic acid in the polishing composition is 0.15% by mass or more and 5% by mass or less.
The polishing composition according to any one of claims 1 to 6, wherein the content of the phosphate in the polishing composition is 0.3% by mass or more and 10% by mass or less.
The polishing composition according to any one of claims 1 to 6, wherein the content of the phosphate in the polishing composition is 0.8 mass% or more and 3 mass% or less.
Phosphate is dipotassium hydrogen phosphate, disodium hydrogen phosphate, diammonium hydrogen phosphate, potassium dihydrogen phosphate, sodium dihydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen pyrophosphate, sodium pyrophosphate The polishing composition according to any one of claims 1 to 8, which is one or more selected from sodium hexametaphosphate and sodium tripolyphosphate.
The mass ratio of sulfamic acid to phosphate (content of sulfamic acid / content of phosphate) in the polishing composition is from 0.01 to 50 in any one of claims 1 to 9. The polishing liquid composition as described.
The mass ratio of sulfamic acid and phosphate (content of sulfamic acid / content of phosphate) in the polishing composition is 0.05 or more and 1 or less, according to any one of claims 1 to 9. The polishing liquid composition as described.
The mass ratio between the abrasive grains and the phosphate in the polishing composition (abrasive grain content / phosphate content) is 0.5 to 26 in any one of claims 1 to 11. The polishing liquid composition as described.
When the phosphate is added to a pH 2 aqueous medium in the same amount as the phosphate content in the polishing composition, the proportion of phosphate present in the form of a salt is pH 2 aqueous. The polishing composition according to any one of claims 1 to 12, which is 10% by mass or more based on the total amount of phosphate added to the medium.
The polishing composition according to any one of claims 1 to 13, wherein the glass hard disk substrate is an aluminoborosilicate glass substrate.
A method for producing a glass hard disk substrate, comprising a step of polishing a glass substrate to be polished using the polishing composition according to any one of claims 1 to 14.
A method for polishing a glass substrate, comprising polishing a glass substrate to be polished using the polishing composition according to any one of claims 1 to 14.