WO2024101242A1 - Composition de liquide de polissage pour substrat de disque magnétique - Google Patents

Composition de liquide de polissage pour substrat de disque magnétique Download PDF

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WO2024101242A1
WO2024101242A1 PCT/JP2023/039439 JP2023039439W WO2024101242A1 WO 2024101242 A1 WO2024101242 A1 WO 2024101242A1 JP 2023039439 W JP2023039439 W JP 2023039439W WO 2024101242 A1 WO2024101242 A1 WO 2024101242A1
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polishing
component
atom
substrate
less
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PCT/JP2023/039439
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English (en)
Japanese (ja)
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大井信
戸田勝章
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花王株式会社
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Publication of WO2024101242A1 publication Critical patent/WO2024101242A1/fr

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  • This disclosure relates to a polishing composition for magnetic disk substrates, and a method for manufacturing and polishing magnetic disk substrates using the same.
  • Patent Document 1 proposes a silica sol for polishing, which is obtained by dispersing non-spherical silica fine particles having an average particle size in the range of 5 to 300 nm as measured by dynamic light scattering in a dispersion medium, has a solid content concentration of 10 to 60 mass%, and has a peak area of Q4 of 88% or more and a peak area of Q3 of 11% or less in the peak area of chemical shifts of -73 to -120 ppm in 29Si-NMR spectrum measurement.
  • Patent Document 2 proposes a method for manufacturing a magnetic disk substrate, which includes a polishing process in which a polishing liquid containing silica abrasive grains as free abrasive grains is supplied between a main surface of a glass substrate and a polishing pad, and the main surface of the glass substrate is polished, wherein the silica abrasive grains have a ratio (Si-OH)/Si of silanol groups (Si-OH) inside the abrasive grains to elemental silicon (Si) in the entire abrasive grains of 0.4 or more.
  • Patent Document 3 proposes a polishing composition containing silica abrasive grains, in which the silica abrasive grains have an average primary particle size of 40 nm or more and an average silanol group density of 1.25 pieces/nm2 or less .
  • the present disclosure relates to a polishing liquid composition for magnetic disk substrates, which contains silica particles (component A), an acid (component B), and water, and in which component A has a silicon atom concentration (atom%) of 28 atom% or more and 38 atom% or less, as measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15°.
  • component A silica particles
  • component B an acid
  • component A has a silicon atom concentration (atom%) of 28 atom% or more and 38 atom% or less, as measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15°.
  • XPS X-ray photoelectron spectroscopy
  • the present disclosure relates to a method for polishing a substrate, the method comprising the step of polishing a substrate to be polished using the polishing composition of the present disclosure, the substrate to be polished being a substrate used in the manufacture of magnetic disk substrates.
  • the present disclosure relates to a method for manufacturing a magnetic disk substrate, comprising the steps of selecting silica particles (component A) having a silicon atom concentration (atom%) of 28 atom% or more and 38 atom% or less, as measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15°, a slurry of the silica particles (component A), or a polishing liquid composition containing the silica particles (component A) as abrasive grains, to obtain a polishing liquid composition containing the silica particles (component A), an acid (component B), and water, and polishing a substrate to be polished using the polishing liquid composition containing the silica particles (component A), an acid (component B), and water.
  • XPS X-ray photoelectron spectroscopy
  • polishing compositions that can further reduce scratches on the substrate surface.
  • polishing speed and scratches there is a problem that improving one will worsen the other.
  • polishing compositions are also required to have excellent dispersion stability.
  • the present disclosure provides a polishing composition that can improve the polishing rate while reducing scratches on the substrate surface after polishing, and has excellent dispersion stability.
  • the present disclosure provides a polishing composition that can improve the polishing rate while reducing scratches on the substrate surface after polishing, and has excellent dispersion stability.
  • the present disclosure is based on the finding that when a polishing liquid composition containing silica particles having a silicon atom concentration (atom %) within a specific range as measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15° is used for polishing a magnetic disk substrate, the polishing rate can be improved, scratches on the substrate surface after polishing can be reduced, and the dispersion stability can be excellent.
  • XPS X-ray photoelectron spectroscopy
  • the silicon atom concentration (atom %) measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15° refers to the percentage of the silicon atom concentration to the sum of the silicon atom (Si) concentration and the oxygen atom (O) concentration, calculated by elemental analysis of the spectrum obtained by measuring component A using XPS at a detection angle of 15°, [Si/(Si+O)] ⁇ 100.
  • X-ray photoelectron spectroscopy (XPS) is a surface analysis method that measures the kinetic energy of photoelectrons emitted when a sample surface is irradiated with soft X-rays.
  • the measurement depth can be adjusted by changing the detection angle.
  • the present disclosure relates to a polishing liquid composition for magnetic disk substrates (hereinafter also referred to as the "polishing liquid composition of the present disclosure”) that contains silica particles (component A), an acid (component B), and water, in which component A has a silicon atom concentration (atom %) of 28 atom % or more and 38 atom % or less relative to the total of the silicon atom concentration and the oxygen atom concentration, as measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15°.
  • XPS X-ray photoelectron spectroscopy
  • the oxygen element in the extreme surface layer of the target silica particle is reduced, the water molecules in the system are also relatively reduced, but the effect is not so great that the silica particles are in contact with each other, so the silica particles are stably dispersed in water.
  • the reduction in the water molecules between the silica particles narrows the distance between the silica particles, and as a result, the contact frequency between the silica particles and the polishing target substrate (polished substrate) is also improved. It is estimated that the stress of the silica particles is dispersed from the depth direction to the entire substrate surface by the improvement in the contact frequency between the silica particles and the polishing target substrate, thereby suppressing the occurrence of local stress on the substrate surface and reducing scratches.
  • the present disclosure need not be construed as being limited to these mechanisms.
  • scratches on the substrate surface can be detected, for example, by an optical defect inspection device, and can be quantitatively evaluated as the number of scratches. Specifically, the number of scratches can be evaluated by the method described in the examples.
  • the polishing composition of the present disclosure contains silica particles (hereinafter also referred to as "component A”) as abrasive grains.
  • Component A is silica particles having a silicon atom concentration (atom%) of 28 atom% or more and 38 atom% or less, measured by X-ray photoelectron spectroscopy (XPS) at a detection angle of 15°.
  • XPS X-ray photoelectron spectroscopy
  • Component A is preferably used in the form of a slurry-like polishing liquid component.
  • Component A may be one type or a combination of two or more types.
  • the silicon atom concentration (atom%) measured by XPS at a detection angle of 15° is 28 atom% or more, preferably 29 atom% or more, and more preferably 30 atom% or more, from the viewpoint of improving the polishing rate, and is 38 atom% or less, preferably 36 atom% or less, and more preferably 34 atom% or less, from the viewpoint of reducing scratches. More specifically, the silicon atom concentration (atom%) measured by XPS at a detection angle of 15° is 28 atom% or more and 38 atom% or less, preferably 29 atom% or more and 36 atom% or less, and more preferably 30 atom% or more and 34 atom% or less.
  • the silicon atom concentration (atom %) measured by XPS at a detection angle of 15° refers to the percentage of the silicon atom concentration to the sum of the silicon atom (Si) concentration and the oxygen atom (O) concentration, calculated by elemental analysis of the spectrum obtained by measuring component A using XPS at a detection angle of 15°, [Si/(Si+O)] ⁇ 100.
  • the silicon atom concentration (atom%) measured by XPS at a detection angle of 45° is preferably 28 atom% or more, more preferably 28.5 atom% or more, and even more preferably 29 atom% or more from the viewpoint of improving the polishing rate, and is preferably 36 atom% or less, more preferably 34 atom% or less, and even more preferably 32 atom% or less from the viewpoint of reducing scratches. More specifically, the silicon atom concentration (atom%) measured by XPS at a detection angle of 45° is preferably 28 atom% or more and 36 atom% or less, more preferably 28.5 atom% or more and 34 atom% or less, and even more preferably 29 atom% or more and 32 atom% or less.
  • the silicon atom concentration (atom %) measured by XPS at a detection angle of 45° refers to the percentage of the silicon atom concentration to the total of the silicon atom (Si) concentration and the oxygen atom (O) concentration calculated by elemental analysis of the spectrum obtained by measuring component A using XPS at a detection angle of 45°, [Si/(Si+O)] ⁇ 100.
  • the silicon atom concentration (atom%) measured by XPS at a detection angle of 75° is preferably 28 atom% or more, more preferably 28.2 atom% or more, and even more preferably 28.4 atom% or more from the viewpoint of improving the polishing rate, and is preferably 36 atom% or less, more preferably 35.5 atom% or less, and even more preferably 35.0 atom% or less from the viewpoint of improving the dispersion stability.
  • the silicon atom concentration (atom%) measured by XPS at a detection angle of 75° is preferably 28 atom% or more and 36 atom% or less, more preferably 28.2 atom% or more and 35.5 atom% or less, and even more preferably 28.4 atom% or more and 35.0 atom% or less.
  • the silicon atom concentration (atom %) measured by XPS at a detection angle of 75° refers to the percentage of the silicon atom concentration to the sum of the silicon atom (Si) concentration and the oxygen atom (O) concentration, calculated by elemental analysis of the spectrum obtained by measuring component A using XPS at a detection angle of 75°, [Si/(Si+O)] ⁇ 100.
  • the concentration ratio (15°/45°) of the silicon atom concentration (atom%) measured by XPS at a detection angle of 15° to the silicon atom concentration (atom%) measured by XPS at a detection angle of 45° is preferably 1.02 or more, more preferably 1.025 or more, and even more preferably 1.03 or more, from the viewpoint of improving the polishing rate, and is preferably 1.4 or less, more preferably 1.3 or less, and even more preferably 1.2 or less, from the viewpoint of reducing scratches. More specifically, the concentration ratio (15°/45°) is preferably 1.02 or more and 1.4 or less, more preferably 1.025 or more and 1.3 or less, and even more preferably 1.03 or more and 1.2 or less.
  • the concentration ratio (15°/75°) between the silicon atom concentration (atom%) measured by XPS under the condition of a detection angle of 15° and the silicon atom concentration (atom%) measured by XPS under the condition of a detection angle of 75° is preferably 1.05 or more, more preferably exceeds 1.05, more preferably 1.06 or more, and even more preferably 1.07 or more, and from the viewpoint of reducing scratches, it is preferably 1.4 or less, more preferably 1.3 or less, more preferably 1.2 or less, even more preferably 1.15 or less, and even more preferably 1.10 or less.
  • the concentration ratio (15°/75°) is preferably 1.05 or more and 1.4 or less, more preferably 1.06 or more and 1.3 or less, more preferably 1.07 or more and 1.2 or less, even more preferably 1.07 or more and 1.15 or less, and even more preferably 1.07 or more and 1.10 or less.
  • the concentration of each atom (Si, O) measured by XPS can be measured using an XPS measuring device manufactured by ULVAC-PHI Inc. that uses ALK ⁇ radiation as the characteristic X-ray.
  • the concentration of silicon atoms (Si) can be calculated, for example, by performing elemental analysis in a binding energy range of 96 to 106 eV on a spectrum obtained by XPS under conditions of a predetermined detection angle (15°, 45°, 75°).
  • the concentration of oxygen atoms (O) can be calculated, for example, by performing elemental analysis in a binding energy range of 526 to 536 eV on a spectrum obtained by XPS under conditions of a predetermined detection angle (15°, 45°, 75°). Specifically, it can be calculated by the measurement method described in the examples.
  • Component A can be produced, for example, by mixing an alkali silicate with a strong acid to prepare a solution containing silica hydrogel, aging the silica within a prescribed temperature range (e.g., 10 to 40° C.), removing the salt in the solution, adding an alkali solution to the silica hydrogel to colloidize the silica hydrogel to obtain a silica sol, and subjecting the silica sol to hydrothermal treatment to grow silica particles.
  • a prescribed temperature range e.g. 10 to 40° C.
  • hydrothermal treatment conditions there are several methods for adjusting the silicon atom concentration of component A, and one example is the control of hydrothermal treatment conditions during the growth process of silica particles.
  • hydrothermal treatment conditions there is a method of adjusting pH by using an alkaline agent such as sodium hydroxide, and controlling heating temperature and pressure by equipment.
  • an alkaline agent such as sodium hydroxide
  • component A examples include colloidal silica, fumed silica, pulverized silica, and surface-modified silica thereof, from the viewpoints of improving the removal rate and reducing scratches. Of these, colloidal silica is preferred. In one or a plurality of embodiments, from the viewpoints of improving the polishing rate and reducing scratches, the abrasive grains contained in the polishing liquid composition of the present disclosure are preferably only Component A, and more preferably only colloidal silica.
  • Component A may be spherical or non-spherical in shape.
  • the average primary particle diameter of Component A when used for finish polishing, is preferably 5 nm or more from the viewpoints of improving the polishing rate and reducing scratches, and from the same viewpoints, is preferably 100 nm or less, and more preferably 40 nm or less. More specifically, the average primary particle diameter of Component A is preferably 5 nm or more and 100 nm or less, and more preferably 5 nm or more and 40 nm or less.
  • the average primary particle diameter of component A when used for rough polishing, is preferably 30 nm or more, more preferably 40 nm or more, and even more preferably 50 nm or more from the viewpoint of improving the polishing rate, and from the same viewpoint, it is preferably 200 nm or less, more preferably 180 nm or less, and even more preferably 160 nm or less. More specifically, in one or more embodiments, the average primary particle diameter of component A is preferably 30 nm or more and 200 nm or less, more preferably 40 nm or more and 180 nm or less, and even more preferably 50 nm or more and 160 nm or less. In the present disclosure, the average primary particle size of component A is calculated using the specific surface area S ( m2 /g) calculated by the nitrogen adsorption method (BET method). The average primary particle size value is a value measured by the method described in the Examples.
  • the content of component A in the polishing composition of the present disclosure is preferably 1 mass% or more, more preferably 2 mass% or more, and even more preferably 3 mass% or more, from the viewpoint of improving the polishing rate, and is preferably 15 mass% or less, more preferably 12 mass% or less, and even more preferably 9 mass% or less, from the viewpoint of reducing scratches. More specifically, the content of component A in the polishing composition of the present disclosure is preferably 1 mass% or more and 15 mass% or less, more preferably 2 mass% or more and 12 mass% or less, and even more preferably 3 mass% or more and 9 mass% or less.
  • component A consists of two or more types of silica particles, the content of component A refers to the total content thereof.
  • the polishing composition of the present disclosure contains an acid (component B).
  • an acid includes the use of an acid or a salt thereof.
  • Component B may be one type or a combination of two or more types.
  • component B examples 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, tripolyphosphoric acid, amidosulfuric acid, and the like; organic acids such as organic phosphoric acid, organic phosphonic acid, and carboxylic acid; and the like.
  • inorganic acids such as nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid, and the like
  • organic acids such as organic phosphoric acid, organic phosphonic acid, and carboxylic acid; and the like.
  • it is preferable to contain inorganic acid and organic phosphonic acid it is preferable to contain inorganic acid.
  • the content of inorganic acid in component B is preferably 0.5 mass% or more, more preferably 0.75 mass% or more, and even more preferably 1.0 mass% or more.
  • the inorganic acid is preferably at least one selected from nitric acid, sulfuric acid, hydrochloric acid, perchloric acid and phosphoric acid, more preferably at least one selected from sulfuric acid and phosphoric acid, and even more preferably phosphoric acid.
  • the organic phosphonic acid is preferably at least one selected from 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotri(methylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), and diethylenetriaminepenta(methylenephosphonic acid), and HEDP is more preferable.
  • HEDP 1-hydroxyethylidene-1,1-diphosphonic acid
  • salts of these acids include salts of the above acids and at least one selected from metals, ammonia, and alkylamines.
  • the above metals include metals belonging to Groups 1 to 11 of the periodic table. Among these, from the viewpoints of improving the polishing rate and reducing scratches, salts of the above acids and metals belonging to Group 1A or ammonia are preferable.
  • the content of component B in the polishing composition of the present disclosure is preferably 0.5 mass% or more, more preferably 0.75 mass% or more, and even more preferably 1.0 mass% or more, from the viewpoint of polishing rate, and is preferably 5.0 mass% or less, more preferably 4.0 mass% or less, and even more preferably 3.0 mass% or less, from the viewpoint of scratches. More specifically, the content of component B in the polishing composition of the present disclosure is preferably 0.5 mass% or more and 5.0 mass% or less, more preferably 0.75 mass% or more and 4.0 mass% or less, and even more preferably 1.0 mass% or more and 3.0 mass% or less. When component B is a combination of two or more types, the content of component B refers to the total content thereof.
  • the polishing composition of the present disclosure contains water as a medium.
  • examples of water include distilled water, ion-exchanged water, pure water, and ultrapure water.
  • the content of water in the polishing composition of the present disclosure can be the remainder excluding component A, component B, and any optional components described below.
  • the polishing composition of the present disclosure may further contain an oxidizing agent (hereinafter, also referred to as "component C") from the viewpoint of improving the polishing rate and reducing scratches.
  • component C is an oxidizing agent that does not contain a halogen atom.
  • Component C may be one type or a combination of two or more types.
  • Component C from the viewpoint of improving the polishing rate and reducing scratches, may be, for example, peroxides, permanganic acid or its salts, chromic acid or its salts, peroxoacids or their salts, oxyacids or their salts, metal salts, nitric acids, sulfuric acids, etc.
  • At least one selected from hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate, and ammonium iron (III) sulfate is preferred, and hydrogen peroxide is more preferred from the viewpoint of improving the polishing rate, preventing metal ions from adhering to the surface of the substrate to be polished, and ease of availability.
  • the content of component C in the polishing liquid composition of the present disclosure is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.1 mass% or more from the viewpoint of improving the polishing rate, and is preferably 4 mass% or less, more preferably 3 mass% or less, and even more preferably 2 mass% or less from the viewpoint of reducing scratches. More specifically, the content of component C in the polishing liquid composition of the present disclosure is preferably 0.01 mass% or more and 4 mass% or less, more preferably 0.05 mass% or more and 3 mass% or less, and even more preferably 0.1 mass% or more and 2 mass% or less.
  • component C is a combination of two or more types, the content of component C refers to the total content thereof.
  • the polishing liquid composition of the present disclosure may contain other components as necessary within a range that does not impair the effects of the present disclosure.
  • other components include heterocyclic aromatic compounds, aliphatic amine compounds, alicyclic amine compounds, thickeners, dispersants, rust inhibitors, basic substances, polishing rate enhancers, surfactants, water-soluble polymers, etc.
  • the pH of the polishing composition of the present disclosure is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more, from the viewpoint of scratches, and is preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less, from the viewpoint of polishing rate. More specifically, the pH of the polishing composition of the present disclosure is preferably 0.1 or more and 6 or less, more preferably 0.3 or more and 5 or less, and even more preferably 0.5 or more and 4 or less.
  • the pH can be adjusted using the above-mentioned acid (component B) or a known pH adjuster.
  • the above pH is the pH of the polishing composition at 25°C, and can be measured using a pH meter, and can be, for example, the value after 2 minutes of immersing the electrode of the pH meter in the polishing composition.
  • the polishing liquid composition of the present disclosure can be produced, for example, by blending component A, component B, and water, and, if desired, optional components (component C and other components) by a known method.
  • the polishing liquid composition of the present disclosure can be produced by blending at least component A, component B, and water.
  • the present disclosure relates to a method for producing a polishing liquid composition, which includes a step of blending at least component A, component B, and water.
  • "blending" includes mixing component A, component B, and water, and optional components (component C and other components) as necessary, simultaneously or in any order.
  • Silica particles may be mixed in the state of a concentrated slurry, or may be mixed after diluting with water or the like.
  • component A is composed of multiple types of silica particles
  • component B is composed of multiple types of acids
  • the multiple types of acids can be blended simultaneously or separately.
  • the blending can be carried out using a mixer such as a homomixer, a homogenizer, an ultrasonic disperser, and a wet ball mill.
  • the preferred amount of each component in the method for producing the polishing composition can be the same as the preferred content of each component in the polishing composition of the present disclosure described above.
  • the polishing composition of the present disclosure may be of a so-called one-component type, in which all components are premixed and supplied to the market, or of a so-called two-component type, in which components are mixed at the time of use.
  • the content of each component in the polishing liquid composition refers to the content of each component at the time of use, that is, at the time when the use of the polishing liquid composition for polishing is started. In one or more embodiments, the content of each component in the polishing composition of the present disclosure can be considered as the blending amount of each component.
  • the polishing composition of the present disclosure may be stored and supplied in a concentrated state to the extent that 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 composition of the present disclosure may be appropriately diluted with the above-mentioned water when used as necessary.
  • the dilution ratio is not particularly limited as long as the content (at the time of use) of each of the above-mentioned components can be secured after dilution, and may be, for example, 10 to 100 times.
  • the present disclosure relates to a kit for preparing the polishing liquid composition of the present disclosure, the kit including a first liquid containing component A and a second liquid containing component B in a mutually unmixed state (hereinafter also referred to as the "polishing liquid kit of the present disclosure").
  • the first liquid and the second liquid may be mixed at the time of use and diluted with water as necessary.
  • the water contained in the first liquid may be the entire amount of water used to prepare the polishing composition, or may be a part of the amount.
  • the second liquid may contain a part of the water used to prepare the polishing composition.
  • the first liquid and the second liquid may each contain the above-mentioned optional components (component C, other components) as necessary.
  • the above-mentioned optional components may be further mixed. According to the present disclosure, it is possible to obtain a polishing composition that can improve the removal rate while reducing scratches on the substrate surface after polishing, and that has excellent dispersion stability.
  • the substrate to be polished is a substrate used for manufacturing a magnetic disk substrate.
  • the surface of the substrate to be polished is polished with the polishing composition of the present disclosure, and then a magnetic layer is formed on the substrate surface by sputtering or the like, thereby manufacturing a magnetic disk substrate.
  • Materials of the substrate to be polished that are suitable for use in this disclosure include, for example, metals or semimetals such as silicon, aluminum, nickel, tungsten, copper, tantalum, and titanium, or alloys thereof; glassy materials 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 resins.
  • the substrate to be polished is suitable for use with metals such as aluminum, nickel, tungsten, and copper, and alloys containing these metals as the main components.
  • Ni-P plated aluminum alloy substrates and glass substrates such as crystallized glass, tempered glass, aluminosilicate glass, and aluminoborosilicate glass are more suitable, and Ni-P plated aluminum alloy substrates are even more suitable.
  • the term "Ni-P plated aluminum alloy substrate” refers to an aluminum alloy substrate whose surface has been ground and then electrolessly plated with Ni-P.
  • the shape of the substrate to be polished can be, for example, a disk, plate, slab, prism, or other shape with a flat surface, or a lens or other shape with a curved surface.
  • a disk-shaped substrate to be polished is suitable.
  • the outer diameter is, for example, about 2 to 100 mm
  • the thickness is, for example, about 0.4 to 2 mm.
  • magnetic disks are manufactured by polishing a substrate that has undergone a grinding process, then polishing it through a rough polishing process and a finish polishing process, and forming it into a magnetic disk in a recording portion forming process.
  • the polishing composition of the present disclosure is a polishing composition for magnetic disk substrates, and is preferably used for polishing in the finish polishing process.
  • the polishing composition of the present disclosure may also be used for polishing in the rough polishing process.
  • the present disclosure relates to a method for polishing a substrate (hereinafter also referred to as the polishing method of the present disclosure), which includes a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure (hereinafter also referred to as the "polishing step"), and the substrate to be polished is a substrate used in the manufacture of a magnetic disk substrate.
  • the polishing method of the present disclosure it is possible to improve the polishing rate and reduce scratches on the substrate surface after polishing, and by using the polishing liquid composition of the present disclosure, which has excellent dispersion stability, it is possible to manufacture high-quality magnetic disk substrates with high yield and good productivity.
  • the substrate to be polished in the polishing method of the present disclosure can be one used in the manufacture of a magnetic disk substrate, and among them, a substrate used in the manufacture of a magnetic disk substrate for a perpendicular magnetic recording system is preferable.
  • the polishing step in the polishing method of the present disclosure is a step of supplying the polishing liquid composition of the present disclosure to the surface of the substrate to be polished, contacting a polishing pad with the surface to be polished, and moving at least one of the polishing pad and the substrate to be polished to perform polishing, or a step of sandwiching the substrate to be polished between a platen to which a polishing pad such as a nonwoven organic polymer-based polishing cloth is attached, and supplying the polishing liquid composition of the present disclosure to the polishing machine while moving the platen and the substrate to be polished to polish the substrate to be polished.
  • the polishing pad used in the polishing step is not particularly limited, and may be, for example, a suede type, a nonwoven fabric type, a polyurethane independent foam type, or a two-layer type in which these are laminated, and from the viewpoint of improving the polishing speed, a suede type polishing pad is preferred.
  • the polishing load in the polishing step is preferably 5.9 kPa or more, more preferably 6.9 kPa or more, and even more preferably 7.5 kPa or more from the viewpoint of improving the polishing rate, and is preferably 20 kPa or less, more preferably 18 kPa or less, and even more preferably 16 kPa or less from the viewpoint of reducing scratches.
  • the polishing load refers to the pressure of the platen applied to the polishing surface of the substrate to be polished during polishing.
  • the polishing load can be adjusted by applying air pressure or a weight to at least one of the platen and the substrate to be polished.
  • the supply rate of the polishing liquid composition of the present disclosure in the polishing step 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, even more preferably 0.07 mL/min or more and 1 mL/min or less, and even more preferably 0.07 mL/min or more and 0.5 mL/min or less, per 1 cm2 of the substrate to be polished.
  • the polishing composition of the present disclosure can be supplied to the polishing machine, for example, by continuous supply using a pump or the like.
  • supplying the polishing composition to the polishing machine in addition to supplying it as a single liquid containing all components, it can also be divided into multiple compounding component liquids and supplied as two or more liquids, taking into consideration the stability of the polishing composition.
  • the multiple compounding component liquids are mixed, for example, in the supply pipe or on the substrate to be polished, to produce the polishing composition of the present disclosure.
  • 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"), which includes a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure (hereinafter also referred to as the "polishing step").
  • the polishing step in the substrate manufacturing method of the present disclosure is a rough polishing step and/or a finish polishing step.
  • the substrate manufacturing method of the present disclosure is particularly suitable for manufacturing a magnetic disk substrate for a perpendicular magnetic recording system.
  • the polishing method and conditions in the polishing step in the substrate manufacturing method of the present disclosure include the same method and conditions as those in the polishing step in the polishing method of the present disclosure described above.
  • the substrate manufacturing method of the present disclosure may further include a step of selecting component A contained in the polishing liquid composition of the present disclosure, a slurry of component A, or a polishing liquid composition containing component A as abrasive grains, to obtain the polishing liquid composition of the present disclosure.
  • the substrate manufacturing method of the present disclosure is a method for manufacturing a magnetic disk substrate, which includes a step of selecting component A, a slurry of component A, or a polishing liquid composition containing component A as abrasive grains to obtain a polishing liquid composition containing component A, component B, and water (the polishing liquid composition of the present disclosure), and a step of polishing a substrate to be polished using the polishing liquid composition of the present disclosure.
  • the step of obtaining the polishing liquid composition of the present disclosure includes preparing the polishing liquid composition of the present disclosure using component A, a slurry of component A, or a polishing liquid composition containing component A as abrasive grains.
  • the polishing step in the substrate manufacturing method of the present disclosure is a step of supplying the polishing liquid composition of the present disclosure to the surface of the substrate to be polished, contacting the surface to be polished with a polishing pad, and moving at least one of the polishing pad and the substrate to be polished to perform polishing.
  • the polishing step in the substrate manufacturing method of the present disclosure is a step of sandwiching the substrate to be polished between a platen to which a polishing pad such as a nonwoven organic polymer-based polishing cloth is attached, and polishing the substrate to be polished by moving the platen and the substrate to be polished while supplying the polishing liquid composition of the present disclosure to the polishing machine.
  • the polishing process of the substrate to be polished is preferably carried out in the second stage or later, and more preferably in the final polishing process or finish polishing process.
  • a separate polishing machine may be used for each step to avoid contamination with abrasive grains or polishing liquid composition from the previous step, and when separate polishing machines are used, it is preferable to clean the substrate to be polished after each polishing process.
  • the polishing liquid composition of the present disclosure can also be used in circulating polishing in which the polishing liquid used is reused. There are no particular limitations on the polishing machine, and any known polishing machine for substrate polishing can be used.
  • the substrate manufacturing method disclosed herein can improve the polishing rate while reducing scratches on the substrate surface after polishing, and by using the polishing composition disclosed herein, which has excellent dispersion stability, high-quality magnetic disk substrates can be manufactured with high yield and good productivity.
  • the present disclosure relates to silica particles having a silicon atom concentration (atom%) of 28 atom% or more and 38 atom% or less, as measured by X-ray photoelectron spectroscopy (XPS) under a detection angle of 15° (hereinafter, the silica particles having this silicon atom concentration are also referred to as "silica particles of the present disclosure").
  • the silica particles of the present disclosure can be suitably used as abrasive grains for polishing magnetic disk substrates.
  • the silica particles of the present disclosure are the above-mentioned component A.
  • the silicon atom concentration of the silica particles of the present disclosure measured by X-ray photoelectron spectroscopy (XPS) under the condition of detection angle 15° is preferably 28 atom% or more, more preferably 29 atom% or more, and even more preferably 30 atom% or more from the viewpoint of improving the polishing rate when the silica particles of the present disclosure are used as abrasive grains for polishing magnetic disk substrates, and is preferably 38 atom% or less, more preferably 36 atom% or less, and even more preferably 34 atom% or less from the viewpoint of reducing scratches.
  • the silicon atom concentration of the silica particles of the present disclosure measured by X-ray photoelectron spectroscopy (XPS) under the condition of detection angle 15° is preferably 28 atom% or more and 38 atom% or less, more preferably 29 atom% or more and 36 atom% or less, and even more preferably 30 atom% or more and 34 atom% or less.
  • the silicon atom concentration of the silica particles of the present disclosure measured by X-ray photoelectron spectroscopy (XPS) under the condition of detection angle 75° is preferably 28 atom% or more, more preferably 28.2 atom% or more, and even more preferably 28.4 atom% or more from the viewpoint of improving the polishing rate when the silica particles of the present disclosure are used as abrasive grains for polishing magnetic disk substrates, and from the viewpoint of reducing scratches, it is preferably 36 atom% or less, more preferably 35.5 atom% or less, and even more preferably 35.0 atom% or less.More specifically, the silicon atom concentration of the silica particles of the present disclosure measured by X-ray photoelectron spectroscopy (XPS) under the condition of detection angle 75° is preferably 28 atom% or more and 36 atom% or less, more preferably 28.2 atom% or more and 35.5 atom% or less, and even more preferably 28.4 atom% or more and 3
  • silica particles A1 to A12 (component A or non-component A)
  • the silica particles A1 to A12 shown in Table 1 were prepared as follows.
  • the alkali silicate which is the raw material of silica microparticles, is dissolved in water to a concentration of 2 to 8% by mass.
  • a strong acid such as hydrochloric acid, sulfuric acid, or nitric acid is added to the aqueous solution to neutralize the silicic acid, thereby forming a silica hydrogel.
  • the pH at this time is preferably about 4 to 6.
  • the hydrogel of the alkali silicate neutralized with the strong acid is allowed to stand at a temperature range of 10 to 40°C for 1 to 5 hours to allow the silica to mature.
  • the hydrogel is then washed with pure water or alkaline water to remove the salt.
  • An alkaline solution such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide is added to the washed dispersion, and the pH of the dispersion is adjusted to a range of 6 to 12.
  • the temperature at this time is preferably 40 to 120°C.
  • the dispersion thus adjusted is stirred for about 30 minutes to 3 hours to form a colloidal silica hydrogel.
  • the obtained silica sol is then subjected to hydrothermal treatment at a temperature of 100 to 300° C.
  • silica particles A1 Colloidal silica, BET specific surface area 136.4 m 2 /g Silica particles A2 are obtained by preparing them using the same production procedure as silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C. to 300° C.), pressure (0.1 to 0.3 MPa), and time (30 minutes to 6 hours) and adjusting the silicon atom concentration at a detection angle of 15° to be 28 atom % or more and 38 atom % or less.
  • A3 Colloidal silica, BET specific surface area 124.0 m 2 /g Silica particles A3 are obtained by preparing them using the same production procedure as silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C. to 300° C.), pressure (0.1 to 0.3 MPa), and time (1 hour to 6 hours) and adjusting the silicon atom concentration at a detection angle of 15° to be 28 atom % or more and 38 atom % or less.
  • A4 Colloidal silica, BET specific surface area 97.4 m 2 /g Silica particles A4 are obtained by preparing them using the same production procedure as silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C.
  • A5 Colloidal silica, BET specific surface area 124.0 m 2 /g Silica particles A5 are obtained by preparing the silica particles A1 using the same production procedure as silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C.
  • A6 Colloidal silica, BET specific surface area 143.5 m 2 /g Silica particles A6 are obtained by preparing the silica particles A6 using the same production procedure as for silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C.
  • A7 Colloidal silica, BET specific surface area 30.0 m 2 /g Silica particles A7 are obtained by preparing them using the same production procedure as silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C. to 300° C.), pressure (0.1 to 0.3 MPa), and time (3 to 6 hours) and adjusting the silicon atom concentration at a detection angle of 15° to be 28 atom % or more and 38 atom % or less.
  • Silica particles A8 Colloidal silica, BET specific surface area 31.0 m 2 /g Silica particles A8 are obtained by preparing them using the same production procedure as silica particles A1, controlling the hydrothermal treatment conditions of temperature (100° C. to 300° C.), pressure (0.1 to 0.3 MPa), and time (3 to 6 hours) and adjusting the silicon atom concentration at a detection angle of 15° to be 28 atom % or more and 38 atom % or less.
  • Non-Component A Ultra-high purity colloidal silica, BET specific surface area 113.6 m 2 /g
  • A10 ground silica, BET specific surface area 27.8 m 2 /g
  • A11 Colloidal silica, BET specific surface area 136.4 m 2 /g
  • the silica particles A11 are obtained by preparing the silica particles A1 using the same production procedure as for the silica particles A1, and controlling the hydrothermal treatment conditions, ie, temperature (100° C. to 300° C.), pressure (0.1 to 0.3 MPa), and time (30 minutes to 6 hours), so that the silicon atom concentration at a detection angle of 15° is 28 atom % or more and 38 atom % or less. Thereafter, the silica particles A11 are stored in an aqueous solution having a pH of 11 to 13 for 12 hours.
  • A12 Colloidal silica, BET specific surface area 30.3 m 2 /g
  • Polishing liquid compositions (pH 1.6) of Examples 1 to 8 and Comparative Examples 1 to 5 shown in Tables 1 and 2 were prepared by mixing and stirring silica particles A1 to A12 (component A or non-component A) shown in Table 1, acid (component B), oxidizing agent (component C) and ion-exchanged water.
  • the content (mass %, effective amount) of each component in each polishing liquid composition was 6 mass % for silica particles (component A or non-component A), 1.6 mass % for acid (component B), and 1.0 mass % for oxidizing agent (component C).
  • the content of ion-exchanged water in each polishing liquid composition is the remainder excluding component A or non-component A, component B, and component C.
  • the concentration of each atom (Si, O) measured by XPS is measured using an XPS measuring device manufactured by ULVAC-PHI Inc. that uses ALK ⁇ rays as characteristic X-rays.
  • the concentration of silicon atoms (Si) is calculated by performing elemental analysis of a spectrum obtained by XPS under conditions of predetermined detection angles (15°, 45°, 75°) in a binding energy range of 96 to 106 eV.
  • the concentration of oxygen atoms (O) is calculated by performing elemental analysis of a spectrum obtained by XPS under conditions of predetermined detection angles (15°, 45°, 75°) in a binding energy range of 526 to 536 eV.
  • the average primary particle size (nm) of the silica particles (component A) was calculated from the specific surface area S (m 2 /g) calculated by the BET (nitrogen adsorption) method according to the following formula.
  • Average primary particle size (nm) 2727/S
  • the specific surface area S of component A was measured by carrying out the following [pretreatment], and then weighing out about 0.1 g of a measurement sample to four decimal places into a measurement cell, drying the sample for 30 minutes in an atmosphere at 110°C immediately before measuring the specific surface area, and then measuring the specific surface area S by a nitrogen adsorption method (BET method) using a specific surface area measuring device (Micromeritic automatic specific surface area measuring device "Flowsorb III2305", manufactured by Shimadzu Corporation).
  • BET method nitrogen adsorption method
  • Flowsorb III2305" manufactured by Shimadzu Corporation
  • pH Measurement The pH of the polishing composition was measured at 25° C. using a pH meter (manufactured by DKK-TOA Corporation), and the value measured 2 minutes after immersing the electrode in the polishing composition was recorded.
  • polishing Method The prepared polishing compositions of Examples 1 to 8 and Comparative Examples 1 to 5 were used to polish the following substrates under the polishing conditions shown below (Examples 1 to 6 and Comparative Examples 1 and 2: finish polishing, Examples 7 to 8 and Comparative Examples 3 to 5: rough polishing). Then, the polishing rate, number of scratches, and dispersion stability were measured by the measurement methods described below, and the results are shown in Tables 1 and 2.
  • the substrate to be polished was a Ni-P plated aluminum alloy substrate that had been roughly polished with a polishing composition containing alumina abrasive grains.
  • the substrate had a thickness of 0.6 mm, an outer diameter of 97 mm, an inner diameter of 25 mm, and a center line average roughness Ra of 1 nm as measured by an AFM (Digital Instrument NanoScope IIIa Multi Mode AFM).
  • AFM Digital Instrument NanoScope IIIa Multi Mode AFM
  • the substrate to be polished was an Ni-P plated aluminum alloy substrate having a thickness of 0.8 mm, a diameter of 95 mm, and an inner diameter of 25 mm.
  • Polishing test machine Speedfam's "Double-sided 9B polishing machine” Polishing pad: Fujibo suede type (foam layer: polyurethane elastomer, thickness 0.9 mm, average pore size 10 ⁇ m) Amount of polishing composition supplied: 100 mL/min (supply rate per 1 cm2 of substrate to be polished: 0.076 mL/min) Lower platen rotation speed: 32.5 rpm Polishing load: 10.5 kPa Polishing time: 5 minutes Number of substrates: 10 [Rough polishing conditions (Examples 7-8, Comparative Examples 3-5)] Polishing test machine: Speedfam's "Double-sided 9B polishing machine” Polishing pad: Fujibo suede type (foam layer: polyurethane elastomer, thickness 1.0 mm, average pore size 30 ⁇ m) Amount of polishing composition supplied: 100 mL/min (supply rate per 1 cm2 of substrate to be polished: 0.076 mL/min) Lower
  • the dispersion stability was evaluated by adding a silica aqueous solution or silica powder to water so that the target silica particle concentration was 10%.
  • the prepared 10% silica aqueous solution was placed in a test tube and left to stand for 30 minutes. If silica precipitation was visually confirmed in the test tube, the dispersion stability was marked as B, and if silica precipitation was not confirmed and a uniform slurry state was maintained, the dispersion stability was marked as A.
  • the results are shown in Tables 1 and 2.
  • the polishing compositions of Examples 1 to 6 improved the polishing rate and reduced scratches on the substrate surface after polishing, compared to Comparative Examples 1 and 2, in which the silicon atom concentration (atom%) at a detection angle of 15° was not 28 to 38 atom%. Furthermore, the polishing compositions of Examples 1 to 6 had excellent dispersion stability.
  • the polishing compositions of Examples 7 to 8 had improved polishing rates compared to Comparative Examples 3 to 5, in which the silicon atom concentration (atom%) at a detection angle of 15° was less than 28 atom%. Furthermore, the polishing compositions of Examples 7 to 8 had excellent dispersion stability.
  • This disclosure makes it possible to provide, for example, a magnetic disk substrate suitable for high recording density.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing Of Magnetic Record Carriers (AREA)

Abstract

La présente divulgation concerne, selon un mode de réalisation, une composition de liquide de polissage présentant une excellente stabilité de dispersion et apte à la fois à améliorer la vitesse de polissage et à réduire les rayures après polissage sur les surfaces de substrat.　La présente divulgation concerne, selon un mode de réalisation, une composition de liquide de polissage pour un substrat de disque magnétique, la composition de liquide de polissage contenant des particules de silice (composant A), un acide (composant B), et de l'eau, le composant A présentant une concentration en atomes de silicium de 28 à 38 % atomique telle que déterminée par spectroscopie photoélectronique à rayons X (XPS) dans des conditions d'un angle de détection de 15°.
PCT/JP2023/039439 2022-11-08 2023-11-01 Composition de liquide de polissage pour substrat de disque magnétique WO2024101242A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004204152A (ja) * 2002-12-26 2004-07-22 Kao Corp 研磨液組成物
JP2012111869A (ja) * 2010-11-25 2012-06-14 Jgc Catalysts & Chemicals Ltd 研磨用シリカゾル、研磨用組成物及び研磨用シリカゾルの製造方法
WO2016159167A1 (fr) * 2015-03-31 2016-10-06 日揮触媒化成株式会社 Dispersion de particules fines composites à base de silice, procédé de production correspondant, et suspension de polissage comprenant la dispersion de particules fines composites à base de silice

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004204152A (ja) * 2002-12-26 2004-07-22 Kao Corp 研磨液組成物
JP2012111869A (ja) * 2010-11-25 2012-06-14 Jgc Catalysts & Chemicals Ltd 研磨用シリカゾル、研磨用組成物及び研磨用シリカゾルの製造方法
WO2016159167A1 (fr) * 2015-03-31 2016-10-06 日揮触媒化成株式会社 Dispersion de particules fines composites à base de silice, procédé de production correspondant, et suspension de polissage comprenant la dispersion de particules fines composites à base de silice

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