WO2009096217A1 - Process for production of substrate for magnetic recording medium, and magnetic recording medium - Google Patents

Process for production of substrate for magnetic recording medium, and magnetic recording medium Download PDF

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Publication number
WO2009096217A1
WO2009096217A1 PCT/JP2009/050293 JP2009050293W WO2009096217A1 WO 2009096217 A1 WO2009096217 A1 WO 2009096217A1 JP 2009050293 W JP2009050293 W JP 2009050293W WO 2009096217 A1 WO2009096217 A1 WO 2009096217A1
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WO
WIPO (PCT)
Prior art keywords
substrate
magnetic recording
recording medium
oxide film
metal oxide
Prior art date
Application number
PCT/JP2009/050293
Other languages
French (fr)
Japanese (ja)
Inventor
Motohiro Yamada
Hideki Kawai
Masahiro Morikawa
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Konica Minolta Opto, Inc.
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Publication date
Application filed by Konica Minolta Opto, Inc. filed Critical Konica Minolta Opto, Inc.
Priority to JP2009551451A priority Critical patent/JP5440180B2/en
Publication of WO2009096217A1 publication Critical patent/WO2009096217A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73917—Metallic substrates, i.e. elemental metal or metal alloy substrates
    • G11B5/73919—Aluminium or titanium elemental or alloy substrates
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73921—Glass or ceramic substrates

Definitions

  • the present invention relates to a method for manufacturing a magnetic recording medium substrate used in a magnetic disk recording apparatus, and a magnetic recording medium using the magnetic recording medium substrate manufactured by the manufacturing method.
  • a magnetic recording medium is formed by forming a magnetic film on a glass substrate or an aluminum substrate, and information is recorded on the magnetic recording medium by magnetizing the magnetic film with a magnetic head.
  • the magnetic head for recording information on the magnetic recording medium or reading the recorded information is configured to move with respect to the magnetic recording medium in a state of floating from the surface. If irregularities exist on the surface of the magnetic recording medium, the irregularities and the magnetic head collide with each other when the magnetic head moves, and there is a possibility that problems such as damage to the magnetic head and damage to the magnetic recording medium may occur. In order to suppress the occurrence of such a problem, the substrate used for the magnetic recording medium is subjected to high-precision polishing so that the surface thereof becomes a smooth surface, and the occurrence of surface irregularities is suppressed as much as possible.
  • Patent Document 1 a conventional method for manufacturing a glass substrate used for a magnetic recording medium by polishing the glass substrate will be described (for example, Patent Document 1).
  • a glass material is melted (glass melting step)
  • the molten glass is poured into a planar mold, and the molten glass is sandwiched between the molds and press-molded to produce a disk-shaped glass substrate (press Molding process).
  • a circular through-hole is formed in the center of the surface of the glass substrate using a diamond core drill to produce a donut-shaped glass substrate (coring step).
  • the doughnut-shaped glass substrate is ground by a double-side polishing machine holding a plate with diamond pellets attached (first lapping process).
  • first lapping process both surfaces of the glass substrate are ground and the parallelism, flatness, and thickness of the glass substrate are preliminarily adjusted.
  • the glass substrate whose parallelism is preliminarily adjusted is ground and chamfered at the outer peripheral end face and the inner peripheral end face of the hole, and the outer diameter dimension, roundness, inner diameter dimension of the hole, etc. are finely adjusted. (End grinding process).
  • the glass substrate whose outer diameter is finely adjusted, the inner peripheral end surface and the outer peripheral end surface are polished, and the end surface is mirror-finished (end surface polishing step).
  • the glass substrate whose end face has been polished is ground again on both surfaces, and the parallelism, flatness and thickness of the glass substrate are finely adjusted (second lapping step).
  • the glass substrate with finely adjusted parallelism and the like is polished on both surfaces to make the surface unevenness uniform (polishing step).
  • polishing step damage to the glass substrate due to grinding performed in the lapping process is removed (first polishing process), and then damage remaining in the first polishing process is removed (second polishing process).
  • the polished glass substrate is used as a substrate for a magnetic recording medium.
  • NiP is deposited on the surface by electroless plating. And like a glass substrate, the surface is smoothed by grind
  • polishing process for example, patent document 2.
  • a magnetic recording medium is manufactured by depositing a magnetic material on the surface of a glass substrate or aluminum substrate whose surface has been polished by sputtering or the like.
  • the present invention solves the above-described problem, and a method for manufacturing a magnetic recording medium substrate capable of improving the smoothness of the magnetic recording medium substrate without omitting a part of the polishing step, and the method thereof
  • An object of the present invention is to provide a magnetic recording medium using the magnetic recording medium substrate manufactured in (1).
  • a polishing step for polishing a surface of a disk-shaped substrate, and a metal oxide film is formed on the surface of the substrate after the polishing step by a liquid phase deposition method, so that the magnetic And a film forming step for manufacturing the recording medium substrate.
  • a method for manufacturing a magnetic recording medium substrate according to the first aspect wherein in the polishing step, the surface roughness Ra is 0.3 to 5 [nm]. The surface of the substrate is polished.
  • the metal oxide film comprises Si, Ti, V, Mn. , Ni, Zn, Ge, Y, Zr, Nb, Sn, Sb, Ba, Ta, and W, an oxide film containing one or more components.
  • a method for manufacturing a magnetic recording medium substrate according to any one of the first to fourth aspects, wherein the substrate is a glass substrate or an aluminum substrate. To do.
  • a method for manufacturing a magnetic recording medium substrate according to any one of the first to fifth aspects, wherein in the film formation step, the substrate after the polishing step in an aqueous solution.
  • the metal oxide film is formed on the surface of the substrate after the polishing step by hydrolyzing the metal fluoro complex in the aqueous solution.
  • the seventh embodiment of the present invention is a disk-shaped substrate having a surface roughness Ra of 0.3 to 5 [nm], a metal oxide film formed on the surface of the substrate, and the metal oxide film And a magnetic film formed thereon.
  • the present invention it is possible to improve the smoothness of the surface of the magnetic recording medium substrate by forming a metal oxide film on the surface of the substrate by a liquid phase deposition method. This makes it possible to obtain the smoothness required for a substrate used for a magnetic recording medium even if a part of the polishing process is omitted.
  • FIG. 1 is a perspective view of a magnetic recording medium substrate according to an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view of the magnetic recording medium substrate according to the embodiment of the present invention, which is a cross-sectional view taken along the line II-II in FIG. It is sectional drawing which shows the one part cross section of the board
  • FIG. 1 is a perspective view of a magnetic recording medium substrate according to an embodiment of the present invention.
  • 2 is a cross-sectional view of the magnetic recording medium substrate according to the embodiment of the present invention, and is a cross-sectional view taken along the line II-II of FIG.
  • the magnetic recording medium substrate 1 has a disk-shaped substrate 2.
  • a through-hole 21 is formed in the substrate 2 so as to penetrate the substrate 2 in the thickness direction of the substrate 2.
  • a metal oxide film 3 is formed on the surface of the substrate 2.
  • the substrate 2 is a glass substrate or an aluminum substrate.
  • the size of the substrate 2 is not particularly limited, and for example, a substrate of 0.85 inch, 1 inch, 2.5 inch, or 3.5 inch is used.
  • soda lime glass, aluminosilicate glass, lithium silicate glass, or boron silicate glass manufactured by a method such as a float method or a press method is used.
  • the metal oxide film 3 includes one, two or more kinds of components among Si, Ti, V, Mn, Ni, Zn, Ge, Y, Zr, Nb, Sn, Sb, Ba, Ta, or W.
  • An oxide film containing is used.
  • a SiO 2 film or a TiO 2 film is used for the metal oxide film 3.
  • a magnetic recording medium is manufactured by forming a magnetic film on the surface of the magnetic recording medium substrate 1 by sputtering or the like.
  • the magnetic recording medium substrate 1 Next, a method for manufacturing the magnetic recording medium substrate 1 will be described. In this embodiment, the case where the substrate 1 for magnetic recording media is manufactured using a glass substrate for the substrate 2 will be described.
  • a glass material is melted (glass melting process), the molten glass is poured into a planar mold, and the molten glass is sandwiched between the molds and press-molded to obtain a disk-shaped glass.
  • a substrate is produced (press molding process).
  • the surface roughness Ra of the glass substrate is 0.1 to 2.0 [ ⁇ m]
  • the maximum height Rmax is 0.5 to 10.0 [ ⁇ m].
  • a circular through-hole is formed in the center of the surface of the glass substrate using a diamond core drill to produce a donut-shaped glass substrate (coring step).
  • the doughnut-shaped glass substrate is ground by a double-side polishing machine holding a plate with diamond pellets attached (first lapping process).
  • first lapping process both surfaces of the glass substrate are ground and the parallelism, flatness, and thickness of the glass substrate are preliminarily adjusted.
  • the surface roughness Ra of the glass substrate is 0.1 to 0.5 [ ⁇ m]
  • the maximum height Rmax is 0.5 to 5.0 [ ⁇ m].
  • the surface of the glass substrate is ground until the surface roughness Ra becomes 0.1 to 0.5 [ ⁇ m] and the maximum height Rmax becomes 0.5 to 5.0 [ ⁇ m].
  • the glass substrate with pre-adjusted parallelism is ground on the outer peripheral end face and the inner peripheral end face of the hole (end face grinding process), and then the inner peripheral end face and the outer peripheral end face are polished to mirror the end face. (End face polishing process).
  • the glass substrate whose end face has been polished is ground again on both surfaces, and the parallelism, flatness and thickness of the glass substrate are finely adjusted (second lapping step).
  • the surface roughness Ra of the glass substrate is 0.05 to 0.2 [ ⁇ m]
  • the maximum height Rmax is 0.3 to 2.0 [ ⁇ m].
  • the surface of the glass substrate is ground until the surface roughness Ra is 0.05 to 0.2 [ ⁇ m] and the maximum height Rmax is 0.3 to 2.0 [ ⁇ m].
  • polish both surfaces of the glass substrate whose parallelism is finely adjusted polishing process.
  • the surface roughness Ra of the glass substrate is 0.3 to 5 [nm]
  • the maximum height Rmax is 2.0 to 200 [nm].
  • the surface of the glass substrate is polished until the surface roughness Ra becomes 0.3 to 5 [nm] and the maximum height Rmax becomes 2.0 to 200 [nm].
  • the substrate after this polishing step corresponds to the substrate 2.
  • polishing process a known polishing apparatus is used, and both surfaces of the glass substrate are polished using foamed urethane or a suede polishing cloth.
  • the polishing material used in the polishing process is used in the form of a slurry of cerium oxide particles. For example, polishing is performed using cerium oxide having an average particle size of about 0.5 [ ⁇ m].
  • FIG. 3 is a cross-sectional view showing a partial cross section of the magnetic recording medium substrate according to the embodiment of the present invention.
  • FIG. 3A shows the substrate 2 after the polishing process is performed.
  • Groove-shaped polishing marks 4 that cannot be removed in the lapping process or the polishing process remain on the surfaces 22 and 23 of the substrate 2.
  • the surface roughness Ra of the substrate 2 after the polishing process is 0.3 to 5 [nm]
  • the maximum height Rmax is 2.0 to 200 [nm].
  • the magnetic recording medium substrate 1 is manufactured by forming the metal oxide film 3 on the surfaces 22 and 23 of the substrate 2 by a liquid phase deposition method in which a metal oxide film is deposited from the liquid phase. Specifically, the substrate 2 is immersed in an aqueous solution, and the metal oxide film 3 is formed on the surfaces 22 and 23 of the substrate 2.
  • the liquid phase deposition method is a method in which the metal oxide film 3 is directly formed on the substrate 2 using an equilibrium reaction of a metal fluoro complex in an aqueous solution.
  • This reaction can be expressed by the following chemical reaction formula.
  • Chemical reaction formula (1) MF x (x-2n) ⁇ + nH 2 O ⁇ MO n + xF ⁇ +2 nH + Chemical reaction formula (2) H 3 BO 3 + 4H + + 4F ⁇ ⁇ HBF 4 + 3H 2 O
  • Chemical reaction formula (1) is the main reaction, and M represents a metal.
  • the metal fluoro complex is hydrolyzed to produce a metal oxide.
  • fluoride ions are consumed by adding boric acid into the system.
  • the equilibrium reaction of the chemical reaction formula (1) is shifted to the right side to promote the metal oxide precipitation reaction.
  • a uniform metal oxide film 3 is formed on the surfaces 22 and 23 of the substrate 2 as shown in FIG.
  • the smoothness of the surface of the magnetic recording medium substrate 1 can be improved by forming the metal oxide film 3 on the surfaces 22 and 23 of the substrate 2 using the liquid phase deposition method. That is, the surface of the magnetic recording medium substrate 1 can be smoothed by filling the polishing marks 4 left on the surfaces 22 and 23 of the substrate 2 with the metal oxide film 3 deposited by the liquid phase deposition method.
  • the surface roughness Ra of the magnetic recording medium substrate 1 on which the metal oxide film 3 is formed is set to 0.1 to 0.3 [nm], and the maximum height Rmax is set to 1.0 to 10.0 [nm]. nm].
  • the surface roughness Ra of the magnetic recording medium substrate 1 is smoothed to the extent required for the magnetic recording medium. Can be. As a result, it is possible to omit a part of the polishing process in the manufacturing process of the magnetic recording medium substrate, and to reduce the polishing cost and the time required for polishing.
  • the flying height which is the flying height of the head from the surface of the medium, decreases as the recording density increases, and is, for example, 10 nm or less.
  • the magnetic recording medium is required to have a very smooth surface having a surface roughness Ra of several ⁇ m or less without a minute defect.
  • the surface roughness Ra of the magnetic recording medium substrate 1 can be set to 0.1 to 0.3 [nm]. nm] or less can be applied.
  • a second polishing step has been performed as the final polishing step.
  • the glass substrate after the first polishing process is polished until the surface roughness Ra becomes a level required for the magnetic recording medium.
  • the surface roughness Ra is set to 0.1 to 0.3 [nm] and the maximum height Rmax is set to 1.0 to 10. Since the thickness can be set to 0 [nm], the second polishing step can be omitted.
  • the metal oxide film 3 can be formed on the entire surface of the substrate 2. That is, the metal oxide film 3 can be simultaneously formed on both surfaces (surfaces 22 and 23) of the substrate 2, the inner peripheral end surface of the through hole 21, and the outer peripheral end surface of the substrate 2. As described above, since the metal oxide film 3 can be formed on all the surfaces of the substrate 2 in one film forming process, the metal oxide film 3 can be easily formed without increasing the number of film forming processes. Can do. Accordingly, film formation cost and time required for film formation can be reduced. In particular, since a hard disk uses both sides of a magnetic recording medium as recording areas, according to the present invention, it is possible to produce a magnetic recording medium substrate without effectively increasing the number of film forming steps.
  • the substrate 2 may be immersed in the aqueous solution, the possibility of damage to the substrate or particle contamination can be reduced. Furthermore, since it is sufficient to immerse the substrate 2 in an aqueous solution, batch processing is possible, and film formation processing can be performed on a plurality of substrates at a time. In addition, micro minute defects that are likely to occur at the edge portion of the substrate 2 can be filled with the metal oxide film 3, so that the yield of the magnetic recording medium substrate 1 can be improved.
  • a method for forming a metal oxide film on the surface of the substrate 2 there are vacuum deposition, sputtering, CVD (chemical vapor deposition), sol-gel method, etc. in addition to the liquid phase deposition method.
  • gas phase methods such as vacuum deposition, sputtering, and CVD, it is difficult to form a metal oxide film to the back of the polishing marks 4 left on the surface of the substrate 2, so that the substrate for the magnetic recording medium It is difficult to flatten the surface.
  • the film forming apparatus is expensive and it is difficult to reduce the manufacturing cost.
  • the sol-gel method is a simple method, but bubbles (voids) are generated between the surface of the substrate 2 and the sol-gel film, and it is difficult to form a good metal oxide film.
  • the metal oxide film can be formed to the depth of the polishing mark 4 by forming the film by the liquid phase deposition method, and the surface of the magnetic recording medium substrate 1 is flattened. It becomes possible to do.
  • the material used for the substrate 2 is not limited to glass, and even if aluminum is used for the substrate 2, the same actions and effects can be achieved. Is possible.
  • NiP having a thickness of 5 to 8 [ ⁇ m] is formed on the ground aluminum substrate by electroless plating. Similar to the polishing of the glass substrate, the film is formed on the aluminum substrate until the surface roughness Ra becomes 0.3 to 5 [nm] and the maximum height Rmax becomes 2.0 to 200 [nm]. Polish the NiP layer.
  • a metal recording film 3 is formed on the NiP layer by a liquid phase deposition method to produce a magnetic recording medium substrate. The metal oxide film 3 is buried in the polishing marks formed on the NiP layer, so that the surface roughness Ra is 0.1 to 0.3 [nm] and the maximum height Rmax is 1.0 to 10.0 [nm]. ].
  • FIG. 4 is an enlarged cross-sectional view of a part of the cross section of the magnetic recording medium substrate according to the embodiment of the present invention.
  • FIG. 4A shows the surface 22 of the substrate 2 after the polishing process.
  • Groove-shaped polishing marks 4 remain on the surface 22 of the substrate 2.
  • film deposition occurs with a small energy difference at the interface due to the equilibrium reaction. Therefore, when the metal oxide film 3 is formed on the surface of the substrate 2 by the liquid phase deposition method, even if the surface 22 has a groove-like shape such as the polishing mark 4, it does not depend on the shape.
  • the metal oxide film 3 can be formed at the same film formation speed.
  • the shape of the metal oxide film 3 follows the shape of the surface 22 of the substrate 2. For example, as shown in FIG. 4B, when the metal oxide film 3 is formed on the surface 22 of the substrate 2, the metal oxide film 3 is also formed inside the polishing mark 4 and follows the shape of the polishing mark 4. Thus, the trench 41 is formed on the metal oxide film 3.
  • the groove-like shape formed on the surface 22 of the substrate 2 is gradually covered as shown in FIG. 4C, and the size of the groove 42 formed on the surface gradually decreases. .
  • the metal oxide film 3 is buried in the groove caused by the polishing mark 4, and the surface of the magnetic recording medium substrate 1 becomes smooth.
  • the metal oxide film 3 is formed on the surface of the substrate 2 by the liquid phase deposition method, it is possible to obtain the smoothness required for the magnetic recording medium substrate.
  • the metal oxide film 3 having the same thickness as the depth of the polishing mark 4 is formed on the surface, the shape of the polishing mark 4 is substantially covered. Therefore, the metal oxide film 3 is matched to the smoothness of the substrate 2. The amount of film formation may be controlled.
  • the metal oxide film 3 it is preferable to form a SiO 2 film or a TiO 2 film. This is because the use of Si or Ti as the metal allows the equilibrium reaction in the aqueous solution to proceed smoothly, so that the SiO 2 film or the TiO 2 film can be formed relatively easily.
  • a magnetic recording medium is produced by forming a magnetic film on the surface of the magnetic recording medium substrate 1 produced by the above steps. That is, the magnetic recording medium according to the present embodiment has a configuration in which the metal oxide film 3 is formed on the surface of the substrate 2 made of a glass substrate or an aluminum substrate, and the magnetic film is formed on the metal oxide film 3. have.
  • a soft magnetic layer may be formed on the surface of the magnetic recording medium substrate 1, an intermediate layer may be formed on the soft magnetic layer, and a recording layer made of a magnetic film may be formed on the intermediate layer.
  • CoZrNb with a thickness of 5 to 20 [nm] is used for the soft magnetic layer
  • Pt—C with a thickness of 10 to 20 [nm] is used for the intermediate layer.
  • CoCrPt—SiO 2 having a thickness of 10 to 15 [nm] is used for the magnetic film. These films may be formed by sputtering, for example.
  • a NiP layer is formed on the aluminum substrate, and a metal oxide film 3 is formed on the NiP layer.
  • Example 1 (Substrate 2)
  • an aluminosilicate glass substrate produced by a press method was used for the substrate 2.
  • the dimensions of the substrate 2 are shown below.
  • the substrate 2 is a substrate that has been subjected to the above-described first lapping step, second lapping step, and polishing step. In the first lapping process and the second lapping process, both surfaces of the substrate 2 were polished by adjusting the weight of the surface plate applied to the glass substrate and the rotation speed of the surface plate using a double-side polishing machine.
  • polishing was performed with a load of 60 [g / cm 2 ] and a rotation speed of the surface plate of 10 [rpm].
  • a pad and a polishing liquid were used in place of the diamond pellets used in the lapping process.
  • the pad was made of urethane foam having a hardness of 80.
  • cerium oxide having a particle size of 0.6 [ ⁇ m] was dispersed in water and used as a slurry.
  • the weight applied to the glass substrate by the surface plate was 90 [g / cm 2 ], and the rotation speed of the surface plate was 25 [rpm].
  • the surface roughness Ra of the substrate 2 after the polishing process was measured by an atomic force microscope (AFM). As a result, the surface roughness Ra of the substrate 2 was 0.8 [nm], and the maximum height Rmax was 30.0 [nm].
  • (Deposition of metal oxide film 3) In Example 1, a SiO 2 film as the metal oxide film 3 was formed on the surface of the substrate 2. Specifically, a mixed solution obtained by mixing a 0.5 [mol / l] (NH 4 ) 2 SiF 6 aqueous solution and a 0.2 [mol / l] H 3 BO 3 aqueous solution into the mixed solution after the polishing step. The substrate 2 was immersed for 1 hour at room temperature.
  • Example 1 the substrate 2 was immersed in a mixed solution having a capacity of 500 [ml]. In the case of forming the SiO 2 film on a plurality of substrates at a time, the capacity of the mixed solution is increased, the mixed solution is circulated, it is sufficient to immerse the substrate 2 to the mixed solution. (Surface roughness Ra after film formation) By the immersion, a SiO 2 film having a thickness of 30 [nm] was formed on the surface of the substrate 2. Since the substrate 2 was immersed in the mixed solution, an SiO 2 film was formed on all surfaces of the substrate 2. The substrate on which the SiO 2 film is formed corresponds to the magnetic recording medium substrate 1 described above. The surface roughness Ra of the substrate on which the SiO 2 film was formed was measured. As a result, the surface roughness Ra was 0.1 [nm].
  • the SiO 2 film is formed on the surface of the substrate 2 after the polishing process by the liquid phase deposition method, so that the second polishing process is not performed, and the magnetic recording medium substrate is performed.
  • a substrate having a sufficiently smooth surface could be produced.
  • Example 2 In Example 2, a glass substrate was used as the substrate 2 and the polishing process conditions were changed. Specifically, the polishing amount (polishing time) was shortened in the polishing process.
  • the surface roughness Ra of the substrate 2 was 5 [nm], and the maximum height Rmax was 200 [nm]. Then, a SiO 2 film having a thickness of 200 [nm] was formed on the surface of the substrate 2 by the same method as in Example 1.
  • the substrate on which the SiO 2 film is formed corresponds to the magnetic recording medium substrate 1 described above.
  • the surface roughness Ra of the substrate on which the SiO 2 film was formed was 0.1 [nm].
  • Example 3 In Example 3, an aluminum substrate was used as the substrate 2. Since the dimensions of the substrate 2 are the same as those of the first embodiment, description thereof is omitted.
  • the surface of the substrate 2 was ground, and NiP was formed on the surface by electroless plating. In Example 3, a 5 ⁇ m NiP layer was formed. Then, the NiP layer formed on the substrate 2 was polished in the same manner as the polishing for the glass substrate.
  • the surface roughness Ra of the substrate 2 after polishing was 0.8 [nm], and the maximum height Rmax was 30.0 [nm].
  • the substrate 2 was immersed in the same mixed solution as in Example 1. As a result, a SiO 2 film having a thickness of 30 [nm] was formed on the NiP layer.
  • the substrate on which the SiO 2 film is formed corresponds to the magnetic recording medium substrate 1 described above.
  • the surface roughness Ra of the substrate on which the SiO 2 film was formed was measured. As a result, the surface roughness Ra was 0.1 [nm].
  • Example 1 As described above, according to Examples 2 and 3, as in Example 1, a substrate having a sufficiently smooth surface as a magnetic recording medium substrate can be produced without performing the final polishing step. It was.
  • the surface roughness Ra of the substrate 2 after the polishing process was 0.8 [nm] or 5 [nm]. Even if it is other than, the same effect can be produced.
  • the surface roughness Ra after the polishing process is 0.3 to 5 [nm]
  • the surface roughness Ra is set to 0.1 to 0.3 [nm] by forming a SiO 2 film on the substrate 2. nm].
  • the surface roughness Ra can be reduced by changing the time during which the substrate 2 is immersed in the mixed solution or adjusting the concentration of the mixed solution.
  • the thickness can be 0.1 to 0.3 [nm].
  • the SiO 2 film is used as the metal oxide film 3, but the metal oxide film according to the present invention is not limited to the SiO 2 film. Even when an oxide film containing one kind or two or more kinds of components among the plurality of metals described above is used, the same operation and effect as when the SiO 2 film is used can be obtained.
  • the surface roughness Ra can be set to 0.1 to 0.3 [nm] by changing the time for immersing the substrate 2 in the mixed solution or adjusting the concentration of the mixed solution.

Abstract

The surface of a disk-shaped glass or aluminum substrate is ground until the surface roughness (Ra) of the substrate becomes 0.3 to 0.8 [nm]. The ground substrate is immersed in an aqueous solution to cause the hydrolysis of a metal fluoro complex in the aqueous solution, thereby forming a metal oxide film (3) on the ground surface of the substrate. In this manner, a substrate (1) for a magnetic recording medium can be produced, which has a metal oxide film (3) formed on the surface thereof.

Description

磁気記録媒体用基板の製造方法、及び磁気記録媒体Method for manufacturing substrate for magnetic recording medium, and magnetic recording medium
　本発明は、磁気ディスク記録装置に用いられる磁気記録媒体用基板の製造方法、及びその製造方法によって製造された磁気記録媒体用基板を用いた磁気記録媒体に関する。 The present invention relates to a method for manufacturing a magnetic recording medium substrate used in a magnetic disk recording apparatus, and a magnetic recording medium using the magnetic recording medium substrate manufactured by the manufacturing method.
　コンピュータなどに用いられる磁気ディスク記録装置、例えばハードディスクには、ガラス基板又はアルミニウム基板が用いられている。ガラス基板又はアルミニウム基板上に磁性膜を成膜することで磁気記録媒体を作製し、その磁性膜を磁気ヘッドで磁化することにより情報を磁気記録媒体に記録する。 Glass substrates or aluminum substrates are used in magnetic disk recording devices used in computers and the like, for example, hard disks. A magnetic recording medium is formed by forming a magnetic film on a glass substrate or an aluminum substrate, and information is recorded on the magnetic recording medium by magnetizing the magnetic film with a magnetic head.
　磁気記録媒体に情報を記録し、又は、記録された情報を読み取るための磁気ヘッドは、磁気記録媒体に対してその表面から浮上した状態で移動するように構成されている。磁気記録媒体の表面に凹凸が存在すると、磁気ヘッドが移動するときにこれらの凹凸と磁気ヘッドとが衝突し、磁気ヘッドの損傷、磁気記録媒体の損傷などの不具合が生じるおそれがある。このような不具合の発生を抑制するため、磁気記録媒体に用いられる基板はその表面が平滑面となるように高精度の研磨処理が施され、表面の凹凸の発生が極力抑えられている。 The magnetic head for recording information on the magnetic recording medium or reading the recorded information is configured to move with respect to the magnetic recording medium in a state of floating from the surface. If irregularities exist on the surface of the magnetic recording medium, the irregularities and the magnetic head collide with each other when the magnetic head moves, and there is a possibility that problems such as damage to the magnetic head and damage to the magnetic recording medium may occur. In order to suppress the occurrence of such a problem, the substrate used for the magnetic recording medium is subjected to high-precision polishing so that the surface thereof becomes a smooth surface, and the occurrence of surface irregularities is suppressed as much as possible.
　ここで、ガラス基板を研磨して、磁気記録媒体に用いられるガラス基板を製造する従来の方法について説明する（例えば特許文献１）。まず、ガラス素材を溶融し（ガラス溶融工程）、溶融したガラスを平面形状の金型に流し込み、その金型で溶融ガラスを挟むことによりプレス成形し、円板状のガラス基板を作製する（プレス成形工程）。そのガラス基板の表面の中心部にダイヤモンドコアドリルを用いて円状の貫通孔を形成し、ドーナツ状のガラス基板を作製する（コアリング工程）。 Here, a conventional method for manufacturing a glass substrate used for a magnetic recording medium by polishing the glass substrate will be described (for example, Patent Document 1). First, a glass material is melted (glass melting step), the molten glass is poured into a planar mold, and the molten glass is sandwiched between the molds and press-molded to produce a disk-shaped glass substrate (press Molding process). A circular through-hole is formed in the center of the surface of the glass substrate using a diamond core drill to produce a donut-shaped glass substrate (coring step).
　その後、ダイヤモンドペレットを貼り付けたプレートを保持した両面研磨機にて、ドーナツ状のガラス基板を研削加工する（第１ラッピング工程）。この第１ラッピング工程では、ガラス基板の両表面を研削加工し、ガラス基板の平行度、平坦度、及び厚さを予備調整する。 Then, the doughnut-shaped glass substrate is ground by a double-side polishing machine holding a plate with diamond pellets attached (first lapping process). In the first lapping step, both surfaces of the glass substrate are ground and the parallelism, flatness, and thickness of the glass substrate are preliminarily adjusted.
　平行度などが予備調整されたガラス基板は、外周端面と孔の内周端面とが研削され、面取りされて、ガラス基板の外径寸法、真円度、及び孔の内径寸法などが微調整される（端面研削工程）。外径寸法などが微調整されたガラス基板は、内周端面と外周端面とが研磨され、端面の鏡面化が行われる（端面研磨工程）。 The glass substrate whose parallelism is preliminarily adjusted is ground and chamfered at the outer peripheral end face and the inner peripheral end face of the hole, and the outer diameter dimension, roundness, inner diameter dimension of the hole, etc. are finely adjusted. (End grinding process). The glass substrate whose outer diameter is finely adjusted, the inner peripheral end surface and the outer peripheral end surface are polished, and the end surface is mirror-finished (end surface polishing step).
　端面が研磨されたガラス基板は両表面を再度、研削加工され、ガラス基板の平行度、平坦度、及び厚さが微調整される（第２ラッピング工程）。平行度などが微調整されたガラス基板は、両表面が研磨され、表面の凹凸が均一にされる（ポリッシング工程）。ポリッシング工程では、ラッピング工程で実施された研削によるガラス基板のダメージを除去し（第１ポリッシング工程）、次に、第１ポリッシング工程で残存するダメージを除去する（第２ポリッシング工程）。そして、ポリッシング加工されたガラス基板が、磁気記録媒体用の基板に用いられる。 The glass substrate whose end face has been polished is ground again on both surfaces, and the parallelism, flatness and thickness of the glass substrate are finely adjusted (second lapping step). The glass substrate with finely adjusted parallelism and the like is polished on both surfaces to make the surface unevenness uniform (polishing step). In the polishing process, damage to the glass substrate due to grinding performed in the lapping process is removed (first polishing process), and then damage remaining in the first polishing process is removed (second polishing process). The polished glass substrate is used as a substrate for a magnetic recording medium.
　また、アルミニウム基板については、表面を研削した後、無電解めっきによって表面にＮｉＰを成膜する。そして、ガラス基板と同様に、複数の研磨工程によってＮｉＰ層を研磨することで、表面を平滑にする（例えば特許文献２）。 For the aluminum substrate, after the surface is ground, NiP is deposited on the surface by electroless plating. And like a glass substrate, the surface is smoothed by grind | polishing a NiP layer by a some grinding | polishing process (for example, patent document 2).
　そして、表面が研磨されたガラス基板やアルミニウム基板の表面に磁性材料をスパッタリングなどにより成膜することで、磁気記録媒体を作製する。
特開２００３－３６５２２号公報 特開２００１－２０７１６１号公報 Then, a magnetic recording medium is manufactured by depositing a magnetic material on the surface of a glass substrate or aluminum substrate whose surface has been polished by sputtering or the like.
JP 2003-36522 A JP 2001-207161 A
　しかしながら、従来においては、表面が平滑なガラス基板やアルミニウム基板を作製するためには、上述したように複数の研磨工程を施す必要があった。その結果、研磨コストと研磨に要する時間とが増大する問題があった。また、磁気記録媒体の記録密度の高密度化により、表面がより平滑な基板が要求されている。 However, conventionally, in order to produce a glass substrate or an aluminum substrate having a smooth surface, it has been necessary to perform a plurality of polishing steps as described above. As a result, there is a problem that the polishing cost and the time required for polishing increase. Further, as the recording density of the magnetic recording medium is increased, a substrate having a smoother surface is required.
　本発明は上記の問題を解決するものであり、研磨工程の一部を省いても、磁気記録媒体用基板の平滑性を向上させることが可能な磁気記録媒体用基板の製造方法、及びその方法で製造された磁気記録媒体用基板を用いた磁気記録媒体を提供することを目的とする。 The present invention solves the above-described problem, and a method for manufacturing a magnetic recording medium substrate capable of improving the smoothness of the magnetic recording medium substrate without omitting a part of the polishing step, and the method thereof An object of the present invention is to provide a magnetic recording medium using the magnetic recording medium substrate manufactured in (1).
　本発明の第１の形態は、円板状の基板の表面を研磨する研磨工程と、前記研磨工程後の基板に対して、液相析出法によって表面に金属酸化膜を成膜して、磁気記録媒体用基板を製造する成膜工程と、を含むことを特徴とする磁気記録媒体用基板の製造方法である。 According to a first aspect of the present invention, a polishing step for polishing a surface of a disk-shaped substrate, and a metal oxide film is formed on the surface of the substrate after the polishing step by a liquid phase deposition method, so that the magnetic And a film forming step for manufacturing the recording medium substrate. A method for manufacturing a magnetic recording medium substrate.
　また、本発明の第２の形態は、第１の形態に係る磁気記録媒体用基板の製造方法であって、前記研磨工程では、表面粗さＲａが０．３～５［ｎｍ］になるまで、前記基板の表面を研磨することを特徴とする。 According to a second aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium substrate according to the first aspect, wherein in the polishing step, the surface roughness Ra is 0.3 to 5 [nm]. The surface of the substrate is polished.
　また、本発明の第３の形態は、第１の形態又は第２の形態のいずれかに係る磁気記録媒体用基板の製造方法であって、前記金属酸化膜は、二酸化ケイ素の膜であることを特徴とする。 According to a third aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium substrate according to any one of the first and second aspects, wherein the metal oxide film is a silicon dioxide film. It is characterized by.
　また、本発明の第４の形態は、第１の形態又は第２の形態のいずれかに係る磁気記録媒体用基板の製造方法であって、前記金属酸化膜は、Ｓｉ、Ｔｉ、Ｖ、Ｍｎ、Ｎｉ、Ｚｎ、Ｇｅ、Ｙ、Ｚｒ、Ｎｂ、Ｓｎ、Ｓｂ、Ｂａ、Ｔａ、及びＷの成分のうち、１種類又は２種類以上の成分を含む酸化膜である。 According to a fourth aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium substrate according to any one of the first and second aspects, wherein the metal oxide film comprises Si, Ti, V, Mn. , Ni, Zn, Ge, Y, Zr, Nb, Sn, Sb, Ba, Ta, and W, an oxide film containing one or more components.
　また、本発明の第５の形態は、第１から第４の形態のいずれかに係る磁気記録媒体用基板の製造方法であって、前記基板は、ガラス基板又はアルミニウム基板であることを特徴とする。 According to a fifth aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium substrate according to any one of the first to fourth aspects, wherein the substrate is a glass substrate or an aluminum substrate. To do.
　また、本発明の第６の形態は、第１から第５の形態のいずれかに係る磁気記録媒体用基板の製造方法であって、前記成膜工程では、水溶液中に前記研磨工程後の基板を浸漬させ、前記水溶液中において金属フルオロ錯体が加水分解することにより、前記研磨工程後の基板の表面に前記金属酸化膜を成膜することを特徴とする。 According to a sixth aspect of the present invention, there is provided a method for manufacturing a magnetic recording medium substrate according to any one of the first to fifth aspects, wherein in the film formation step, the substrate after the polishing step in an aqueous solution. The metal oxide film is formed on the surface of the substrate after the polishing step by hydrolyzing the metal fluoro complex in the aqueous solution.
　また、本発明の第７の形態は、表面粗さＲａが０．３～５［ｎｍ］である円板状の基板と、前記基板の表面に形成された金属酸化膜と、前記金属酸化膜上に形成された磁性膜と、を有することを特徴とする磁気記録媒体である。 The seventh embodiment of the present invention is a disk-shaped substrate having a surface roughness Ra of 0.3 to 5 [nm], a metal oxide film formed on the surface of the substrate, and the metal oxide film And a magnetic film formed thereon.
　本発明によると、液相析出法によって基板の表面に金属酸化膜を成膜することで、磁気記録媒体用基板の表面の平滑性を向上させることが可能となる。そのことにより、研磨工程の一部を省いても、磁気記録媒体に用いられる基板に要求される平滑性を得ることが可能となる。 According to the present invention, it is possible to improve the smoothness of the surface of the magnetic recording medium substrate by forming a metal oxide film on the surface of the substrate by a liquid phase deposition method. This makes it possible to obtain the smoothness required for a substrate used for a magnetic recording medium even if a part of the polishing process is omitted.
本発明の実施形態に係る磁気記録媒体用基板の斜視図である。1 is a perspective view of a magnetic recording medium substrate according to an embodiment of the present invention. 本発明の実施形態に係る磁気記録媒体用基板の断面図であり、図１のＩＩ－ＩＩ断面図である。FIG. 2 is a cross-sectional view of the magnetic recording medium substrate according to the embodiment of the present invention, which is a cross-sectional view taken along the line II-II in FIG. 本発明の実施形態に係る磁気記録媒体用基板の一部の断面を示す断面図である。It is sectional drawing which shows the one part cross section of the board | substrate for magnetic recording media which concerns on embodiment of this invention. 本発明の実施形態に係る磁気記録媒体用基板の一部の断面を拡大した断面図である。It is sectional drawing to which the one part cross section of the substrate for magnetic recording media which concerns on embodiment of this invention was expanded.
符号の説明Explanation of symbols
　１　磁気記録媒体用基板
　２　基板
　３　金属酸化膜
　４　研磨痕
　２１　貫通孔
　２２、２３　表面
　４１、４２　溝 DESCRIPTION OF SYMBOLS 1 Substrate for magnetic recording media 2 Substrate 3 Metal oxide film 4 Polishing trace 21 Through hole 22, 23 Surface 41, 42 Groove
　本発明の実施形態に係る磁気記録媒体用基板について図１と図２とを参照して説明する。図１は、本発明の実施形態に係る磁気記録媒体用基板の斜視図である。図２は、本発明の実施形態に係る磁気記録媒体用基板の断面図であり、図１のＩＩ－ＩＩ断面図である。 A magnetic recording medium substrate according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a magnetic recording medium substrate according to an embodiment of the present invention. 2 is a cross-sectional view of the magnetic recording medium substrate according to the embodiment of the present invention, and is a cross-sectional view taken along the line II-II of FIG.
　図１と図２とに示すように、本実施形態に係る磁気記録媒体用基板１は、円板状の基板２を有している。基板２には、中央に、基板２の厚さ方向に貫通する貫通孔２１が形成されている。また、基板２の表面には金属酸化膜３が形成されている。 As shown in FIGS. 1 and 2, the magnetic recording medium substrate 1 according to the present embodiment has a disk-shaped substrate 2. A through-hole 21 is formed in the substrate 2 so as to penetrate the substrate 2 in the thickness direction of the substrate 2. A metal oxide film 3 is formed on the surface of the substrate 2.
　基板２には、ガラス基板又はアルミニウム基板が用いられる。基板２の大きさは特に限定されず、例えば、０．８５インチ、１インチ、２．５インチ、又は３．５インチなどの基板が用いられる。また、ガラス基板には、フロート法、又はプレス法などの方法で製造されたソーダライムガラス、アルミノシリケートガラス、リチウムシリケートガラス、又はボロンシリケートガラスなどが用いられる。 The substrate 2 is a glass substrate or an aluminum substrate. The size of the substrate 2 is not particularly limited, and for example, a substrate of 0.85 inch, 1 inch, 2.5 inch, or 3.5 inch is used. As the glass substrate, soda lime glass, aluminosilicate glass, lithium silicate glass, or boron silicate glass manufactured by a method such as a float method or a press method is used.
　金属酸化膜３には、Ｓｉ、Ｔｉ、Ｖ、Ｍｎ、Ｎｉ、Ｚｎ、Ｇｅ、Ｙ、Ｚｒ、Ｎｂ、Ｓｎ、Ｓｂ、Ｂａ、Ｔａ、又はＷの成分のうち、１種類又は２種類以上の成分を含む酸化膜が用いられる。例えば、金属酸化膜３には、ＳｉＯ２膜やＴｉＯ２膜を用いる。 The metal oxide film 3 includes one, two or more kinds of components among Si, Ti, V, Mn, Ni, Zn, Ge, Y, Zr, Nb, Sn, Sb, Ba, Ta, or W. An oxide film containing is used. For example, a SiO 2 film or a TiO 2 film is used for the metal oxide film 3.
　磁気記録媒体用基板１の表面にスパッタリングなどによって磁性膜を成膜することで、磁気記録媒体を作製する。 A magnetic recording medium is manufactured by forming a magnetic film on the surface of the magnetic recording medium substrate 1 by sputtering or the like.
　次に、磁気記録媒体用基板１の製造方法について説明する。本実施形態では、基板２にガラス基板を用いて磁気記録媒体用基板１を製造する場合について説明する。 Next, a method for manufacturing the magnetic recording medium substrate 1 will be described. In this embodiment, the case where the substrate 1 for magnetic recording media is manufactured using a glass substrate for the substrate 2 will be described.
　まず、従来技術と同様に、ガラス素材を溶融し（ガラス溶融工程）、溶融したガラスを平面形状の金型に流し込み、その金型で溶融ガラスを挟み込むことによりプレス成形し、円板状のガラス基板を作製する（プレス成形工程）。このプレス成形後のガラス基板の表面を評価すると、ガラス基板の表面粗さＲａは０．１～２．０［μｍ］になり、最大高さＲｍａｘは０．５～１０．０［μｍ］になる。そのガラス基板の表面の中心部にダイヤモンドコアドリルを用いて円状の貫通孔を形成し、ドーナツ状のガラス基板を作製する（コアリング工程）。 First, as in the prior art, a glass material is melted (glass melting process), the molten glass is poured into a planar mold, and the molten glass is sandwiched between the molds and press-molded to obtain a disk-shaped glass. A substrate is produced (press molding process). When the surface of the glass substrate after press molding is evaluated, the surface roughness Ra of the glass substrate is 0.1 to 2.0 [μm], and the maximum height Rmax is 0.5 to 10.0 [μm]. Become. A circular through-hole is formed in the center of the surface of the glass substrate using a diamond core drill to produce a donut-shaped glass substrate (coring step).
　その後、ダイヤモンドペレットを貼り付けたプレートを保持した両面研磨機にて、ドーナツ状のガラス基板を研削加工する（第１ラッピング工程）。この第１ラッピング工程では、ガラス基板の両表面を研削加工し、ガラス基板の平行度、平坦度、及び厚さを予備調整する。この第１ラッピング工程後のガラス基板の表面を評価すると、ガラス基板の表面粗さＲａは０．１～０．５［μｍ］になり、最大高さＲｍａｘは０．５～５．０［μｍ］になる。換言すると、表面粗さＲａが０．１～０．５［μｍ］になり、最大高さＲｍａｘが０．５～５．０［μｍ］になるまで、ガラス基板の表面を研削する。 Then, the doughnut-shaped glass substrate is ground by a double-side polishing machine holding a plate with diamond pellets attached (first lapping process). In the first lapping step, both surfaces of the glass substrate are ground and the parallelism, flatness, and thickness of the glass substrate are preliminarily adjusted. When the surface of the glass substrate after the first lapping step is evaluated, the surface roughness Ra of the glass substrate is 0.1 to 0.5 [μm], and the maximum height Rmax is 0.5 to 5.0 [μm]. ]become. In other words, the surface of the glass substrate is ground until the surface roughness Ra becomes 0.1 to 0.5 [μm] and the maximum height Rmax becomes 0.5 to 5.0 [μm].
　平行度などが予備調整されたガラス基板は、外周端面と孔の内周端面とが研削され（端面研削工程）、さらに、内周端面と外周端面とが研磨されて、端面の鏡面化が行われる（端面研磨工程）。 The glass substrate with pre-adjusted parallelism is ground on the outer peripheral end face and the inner peripheral end face of the hole (end face grinding process), and then the inner peripheral end face and the outer peripheral end face are polished to mirror the end face. (End face polishing process).
　端面が研磨されたガラス基板は両表面を再度、研削加工され、ガラス基板の平行度、平坦度、及び厚さが微調整される（第２ラッピング工程）。この第２ラッピング工程後のガラス基板の表面を評価すると、ガラス基板の表面粗さＲａは０．０５～０．２［μｍ］になり、最大高さＲｍａｘは０．３～２．０［μｍ］になる。換言すると、表面粗さＲａが０．０５～０．２［μｍ］になり、最大高さＲｍａｘが０．３～２．０［μｍ］になるまで、ガラス基板の表面を研削する。 The glass substrate whose end face has been polished is ground again on both surfaces, and the parallelism, flatness and thickness of the glass substrate are finely adjusted (second lapping step). When the surface of the glass substrate after the second lapping step is evaluated, the surface roughness Ra of the glass substrate is 0.05 to 0.2 [μm], and the maximum height Rmax is 0.3 to 2.0 [μm]. ]become. In other words, the surface of the glass substrate is ground until the surface roughness Ra is 0.05 to 0.2 [μm] and the maximum height Rmax is 0.3 to 2.0 [μm].
　平行度などが微調整されたガラス基板の両表面を研磨する（ポリッシング工程）。このポリッシング工程後のガラス基板の表面を評価すると、ガラス基板の表面粗さＲａは０．３～５［ｎｍ］になり、最大高さＲｍａｘは２．０～２００［ｎｍ］になる。換言すると、表面粗さＲａが０．３～５［ｎｍ］になり、最大高さＲｍａｘが２．０～２００［ｎｍ］になるまで、ガラス基板の表面を研磨する。このポリッシング工程後の基板が基板２に相当する。 Polish both surfaces of the glass substrate whose parallelism is finely adjusted (polishing process). When the surface of the glass substrate after the polishing process is evaluated, the surface roughness Ra of the glass substrate is 0.3 to 5 [nm], and the maximum height Rmax is 2.0 to 200 [nm]. In other words, the surface of the glass substrate is polished until the surface roughness Ra becomes 0.3 to 5 [nm] and the maximum height Rmax becomes 2.0 to 200 [nm]. The substrate after this polishing step corresponds to the substrate 2.
　ポリッシング工程では、公知のポリッシング装置が用いられ、発泡ウレタンやスエード研磨布を用いてガラス基板の両面を研磨する。ポリッシング工程で使用する研磨材は、酸化セリウムの微粒子をスラリー状にして使用する。例えば、平均粒子サイズが０．５［μｍ］程度の酸化セリウムを用いて研磨する。 In the polishing process, a known polishing apparatus is used, and both surfaces of the glass substrate are polished using foamed urethane or a suede polishing cloth. The polishing material used in the polishing process is used in the form of a slurry of cerium oxide particles. For example, polishing is performed using cerium oxide having an average particle size of about 0.5 [μm].
　本実施形態では、ポリッシング工程後のガラス基板（基板２）の表面に金属酸化膜を成膜する。この成膜工程について図３を参照して説明する。図３は、本発明の実施形態に係る磁気記録媒体基板の一部の断面を示す断面図である。 In this embodiment, a metal oxide film is formed on the surface of the glass substrate (substrate 2) after the polishing process. This film forming process will be described with reference to FIG. FIG. 3 is a cross-sectional view showing a partial cross section of the magnetic recording medium substrate according to the embodiment of the present invention.
　図３（ａ）に、ポリッシング工程が施された後の基板２を示す。基板２の表面２２、２３には、ラッピング工程やポリッシング工程では取り除けなかった溝状の研磨痕４が残存している。上述したように、ポリッシング工程後の基板２の表面粗さＲａは０．３～５［ｎｍ］であり、最大高さＲｍａｘは２．０～２００［ｎｍ］である。 FIG. 3A shows the substrate 2 after the polishing process is performed. Groove-shaped polishing marks 4 that cannot be removed in the lapping process or the polishing process remain on the surfaces 22 and 23 of the substrate 2. As described above, the surface roughness Ra of the substrate 2 after the polishing process is 0.3 to 5 [nm], and the maximum height Rmax is 2.0 to 200 [nm].
　そして、図３（ｂ）に示すように、基板２の表面２２、２３上に金属酸化膜３を成膜する。本実施形態では、液相から金属酸化膜を析出させる液相析出法によって、金属酸化膜３を基板２の表面２２、２３上に成膜することで、磁気記録媒体用基板１を作製する。具体的には、水溶液中に基板２を浸漬させて、基板２の表面２２、２３に金属酸化膜３を成膜する。 Then, as shown in FIG. 3B, a metal oxide film 3 is formed on the surfaces 22 and 23 of the substrate 2. In the present embodiment, the magnetic recording medium substrate 1 is manufactured by forming the metal oxide film 3 on the surfaces 22 and 23 of the substrate 2 by a liquid phase deposition method in which a metal oxide film is deposited from the liquid phase. Specifically, the substrate 2 is immersed in an aqueous solution, and the metal oxide film 3 is formed on the surfaces 22 and 23 of the substrate 2.
　液相析出法は、水溶液中において金属フルオロ錯体の平衡反応を利用して金属酸化膜３を基板２に直接成膜する方法である。この反応は、以下の化学反応式で表すことができる。
化学反応式（１）
　ＭＦｘ （ｘ－２ｎ）－＋ｎＨ２Ｏ→ＭＯｎ＋ｘＦ－＋２ｎＨ＋
化学反応式（２）
　Ｈ３ＢＯ３＋４Ｈ＋＋４Ｆ－→ＨＢＦ４＋３Ｈ２Ｏ
　化学反応式（１）が主反応であり、Ｍは金属を表している。 The liquid phase deposition method is a method in which the metal oxide film 3 is directly formed on the substrate 2 using an equilibrium reaction of a metal fluoro complex in an aqueous solution. This reaction can be expressed by the following chemical reaction formula.
Chemical reaction formula (1)
MF x (x-2n) − + nH 2 O → MO n + xF − +2 nH +
Chemical reaction formula (2)
H 3 BO 3 + 4H + + 4F − → HBF 4 + 3H 2 O
Chemical reaction formula (1) is the main reaction, and M represents a metal.
　金属フルオロ錯体が加水分解することにより金属酸化物を生成する。このとき、化学反応式（２）に示すように、系内にホウ酸を添加することによりフッ化物イオンを消費させる。フッ化物イオンが消費されると、化学反応式（１）の平衡反応を右側へシフトさせ、金属酸化物の析出反応を促進させる。この反応によって、図３（ｂ）に示すように、基板２の表面２２、２３に、均一な金属酸化膜３を形成する。 The metal fluoro complex is hydrolyzed to produce a metal oxide. At this time, as shown in the chemical reaction formula (2), fluoride ions are consumed by adding boric acid into the system. When fluoride ions are consumed, the equilibrium reaction of the chemical reaction formula (1) is shifted to the right side to promote the metal oxide precipitation reaction. By this reaction, a uniform metal oxide film 3 is formed on the surfaces 22 and 23 of the substrate 2 as shown in FIG.
　このように液相析出法を用いて金属酸化膜３を基板２の表面２２、２３上に成膜することで、磁気記録媒体用基板１の表面の平滑性を向上させることができる。すなわち、基板２の表面２２、２３に残された研磨痕４に、液相析出法で析出された金属酸化膜３が埋まることで、磁気記録媒体用基板１の表面を平滑にすることができる。例えば、金属酸化膜３が表面に成膜された磁気記録媒体用基板１の表面粗さＲａを０．１～０．３［ｎｍ］にし、最大高さＲｍａｘを１．０～１０．０［ｎｍ］にすることができる。 Thus, the smoothness of the surface of the magnetic recording medium substrate 1 can be improved by forming the metal oxide film 3 on the surfaces 22 and 23 of the substrate 2 using the liquid phase deposition method. That is, the surface of the magnetic recording medium substrate 1 can be smoothed by filling the polishing marks 4 left on the surfaces 22 and 23 of the substrate 2 with the metal oxide film 3 deposited by the liquid phase deposition method. . For example, the surface roughness Ra of the magnetic recording medium substrate 1 on which the metal oxide film 3 is formed is set to 0.1 to 0.3 [nm], and the maximum height Rmax is set to 1.0 to 10.0 [nm]. nm].
　以上のように、本実施形態によると、基板２の表面に金属酸化膜３を形成することで、磁気記録媒体用基板１の表面粗さＲａを、磁気記録媒体に要求されている程度に平滑にすることができる。その結果、磁気記録媒体用基板の製造工程におけるポリッシング工程の一部を省くことが可能となり、研磨コストと研磨に要する時間とを削減することが可能となる。 As described above, according to the present embodiment, by forming the metal oxide film 3 on the surface of the substrate 2, the surface roughness Ra of the magnetic recording medium substrate 1 is smoothed to the extent required for the magnetic recording medium. Can be. As a result, it is possible to omit a part of the polishing process in the manufacturing process of the magnetic recording medium substrate, and to reduce the polishing cost and the time required for polishing.
　また、磁気記録媒体においては、媒体の表面からのヘッド浮上高さであるフライングハイトは記録密度の上昇とともに低下し、例えば、１０［ｎｍ］以下の高さとなっている。このため、磁気記録媒体には、極微少な欠陥もなく、表面粗さＲａが数Å以下の非常に平滑な表面が必要とされている。本実施形態では、金属酸化膜３を成膜することで、磁気記録媒体用基板１の表面粗さＲａを０．１～０．３［ｎｍ］にすることができるため、フライングハイトが１０［ｎｍ］以下になるような磁気記録媒体にも適用することが可能となる。 In the magnetic recording medium, the flying height, which is the flying height of the head from the surface of the medium, decreases as the recording density increases, and is, for example, 10 nm or less. For this reason, the magnetic recording medium is required to have a very smooth surface having a surface roughness Ra of several μm or less without a minute defect. In the present embodiment, since the metal oxide film 3 is formed, the surface roughness Ra of the magnetic recording medium substrate 1 can be set to 0.1 to 0.3 [nm]. nm] or less can be applied.
　従来においては、磁気記録媒体用基板の表面を平滑にするために、最終の研磨工程として、第２ポリッシング工程を施していた。つまり、第１ポリッシング工程後のガラス基板に対して、表面粗さＲａが磁気記録媒体に要求される程度になるまで研磨を行っていた。具体的には、表面粗さＲａが０．１～０．３［ｎｍ］になり、最大高さＲｍａｘが１．０～１０．０［ｎｍ］になるまで、第１ポリッシング工程後のガラス基板に第２ポリッシング工程を施す必要があった。これに対して、本実施形態によると、その第２ポリッシング工程を施さなくても、表面粗さＲａを０．１～０．３［ｎｍ］にし、最大高さＲｍａｘを１．０～１０．０［ｎｍ］にすることができるため、その第２ポリッシング工程を省くことが可能となる。 Conventionally, in order to smooth the surface of the magnetic recording medium substrate, a second polishing step has been performed as the final polishing step. In other words, the glass substrate after the first polishing process is polished until the surface roughness Ra becomes a level required for the magnetic recording medium. Specifically, the glass substrate after the first polishing step until the surface roughness Ra becomes 0.1 to 0.3 [nm] and the maximum height Rmax becomes 1.0 to 10.0 [nm]. It was necessary to perform a second polishing process. On the other hand, according to this embodiment, the surface roughness Ra is set to 0.1 to 0.3 [nm] and the maximum height Rmax is set to 1.0 to 10. Since the thickness can be set to 0 [nm], the second polishing step can be omitted.
　また、水溶液中に基板２を浸漬させるため、基板２のすべての表面に金属酸化膜３を成膜することができる。すなわち、基板２の両面（表面２２、２３）と、貫通孔２１の内周端面と、基板２の外周端面とに同時に金属酸化膜３を成膜することができる。このように、１つの成膜工程で基板２のすべての面に金属酸化膜３を成膜することができるため、成膜工程数を増やさずに、簡便に金属酸化膜３を成膜することができる。そのことにより、成膜コストや成膜に要する時間を削減することができる。特に、ハードディスクは、磁気記録媒体の両面を記録領域として用いるため、本発明によれば、効果的に成膜の工程数を増やさず、磁気記録媒体用基板を作製することが可能となる。 Further, since the substrate 2 is immersed in the aqueous solution, the metal oxide film 3 can be formed on the entire surface of the substrate 2. That is, the metal oxide film 3 can be simultaneously formed on both surfaces (surfaces 22 and 23) of the substrate 2, the inner peripheral end surface of the through hole 21, and the outer peripheral end surface of the substrate 2. As described above, since the metal oxide film 3 can be formed on all the surfaces of the substrate 2 in one film forming process, the metal oxide film 3 can be easily formed without increasing the number of film forming processes. Can do. Accordingly, film formation cost and time required for film formation can be reduced. In particular, since a hard disk uses both sides of a magnetic recording medium as recording areas, according to the present invention, it is possible to produce a magnetic recording medium substrate without effectively increasing the number of film forming steps.
　また、ドライプロセスのように基板の片面ずつ成膜する方法では、基板をチャックする時に基板に損傷を与えたり、パーティクル汚染を与えたりするおそれがある。これに対して、本実施形態によると、水溶液中に基板２を浸漬させれば良いため、基板に損傷を与えたり、パーティクル汚染を与えたりする可能性を低減することができる。さらに、水溶液中に基板２を浸漬させれば良いため、バッチ処理が可能となり、一度に複数枚の基板に対して成膜処理を施すことが可能となる。また、基板２のエッジ部に発生しやすいマイクロ微小欠陥も金属酸化膜３で埋めることができるため、磁気記録媒体用基板１の歩留まりを向上させる効果もある。 Also, in the method of forming a film on each side of the substrate as in a dry process, there is a risk of damaging the substrate or particle contamination when chucking the substrate. On the other hand, according to the present embodiment, since the substrate 2 may be immersed in the aqueous solution, the possibility of damage to the substrate or particle contamination can be reduced. Furthermore, since it is sufficient to immerse the substrate 2 in an aqueous solution, batch processing is possible, and film formation processing can be performed on a plurality of substrates at a time. In addition, micro minute defects that are likely to occur at the edge portion of the substrate 2 can be filled with the metal oxide film 3, so that the yield of the magnetic recording medium substrate 1 can be improved.
　なお、金属酸化膜を基板２の表面に成膜する方法としては、液相析出法の他に、真空蒸着、スパッタリング、ＣＶＤ（化学気相成長）、又はゾルゲル法などがある。しかしながら、真空蒸着、スパッタリング、及びＣＶＤなどのいわゆる気相法では、基板２の表面に残された研磨痕４の奥まで金属酸化膜を成膜することが困難であるため、磁気記録媒体用基板の表面を平坦にすることが困難である。また、成膜装置が高価で製造コストを削減することが困難である。また、ゾルゲル法は簡便な方法であるが、基板２の表面とゾルゲル膜との間に気泡（ボイド）が発生し、良好な金属酸化膜を成膜することが困難である。これに対して、本実施形態によると、液相析出法によって成膜することで、研磨痕４の奥まで金属酸化膜を成膜することができ、磁気記録媒体用基板１の表面を平坦にすることが可能となる。 In addition, as a method for forming a metal oxide film on the surface of the substrate 2, there are vacuum deposition, sputtering, CVD (chemical vapor deposition), sol-gel method, etc. in addition to the liquid phase deposition method. However, in so-called gas phase methods such as vacuum deposition, sputtering, and CVD, it is difficult to form a metal oxide film to the back of the polishing marks 4 left on the surface of the substrate 2, so that the substrate for the magnetic recording medium It is difficult to flatten the surface. In addition, the film forming apparatus is expensive and it is difficult to reduce the manufacturing cost. The sol-gel method is a simple method, but bubbles (voids) are generated between the surface of the substrate 2 and the sol-gel film, and it is difficult to form a good metal oxide film. On the other hand, according to the present embodiment, the metal oxide film can be formed to the depth of the polishing mark 4 by forming the film by the liquid phase deposition method, and the surface of the magnetic recording medium substrate 1 is flattened. It becomes possible to do.
　液相析出法は、常温の液相で金属酸化膜を成膜することができるため、基板２に用いる材料はガラスに限られず、基板２にアルミニウムを用いても同じ作用及び効果を奏することが可能である。基板２にアルミニウム基板を用いる場合、研削したアルミニウム基板上に、厚さが５～８［μｍ］のＮｉＰを無電解めっきによって成膜する。そして、ガラス基板に対する研磨と同様に、表面粗さＲａが０．３～５［ｎｍ］になり、最大高さＲｍａｘが２．０～２００［ｎｍ］になるまで、アルミニウム基板上に成膜されたＮｉＰ層を研磨する。そして、ガラス基板と同様に、液相析出法によってＮｉＰ層上に金属酸化膜３を成膜することで磁気記録媒体用基板を作製する。ＮｉＰ層上に形成された研磨痕に金属酸化膜３が埋まることで、表面粗さＲａを０．１～０．３［ｎｍ］にし、最大高さＲｍａｘを１．０～１０．０［ｎｍ］にすることができる。 In the liquid phase deposition method, since a metal oxide film can be formed in a liquid phase at room temperature, the material used for the substrate 2 is not limited to glass, and even if aluminum is used for the substrate 2, the same actions and effects can be achieved. Is possible. When an aluminum substrate is used as the substrate 2, NiP having a thickness of 5 to 8 [μm] is formed on the ground aluminum substrate by electroless plating. Similar to the polishing of the glass substrate, the film is formed on the aluminum substrate until the surface roughness Ra becomes 0.3 to 5 [nm] and the maximum height Rmax becomes 2.0 to 200 [nm]. Polish the NiP layer. Then, similarly to the glass substrate, a metal recording film 3 is formed on the NiP layer by a liquid phase deposition method to produce a magnetic recording medium substrate. The metal oxide film 3 is buried in the polishing marks formed on the NiP layer, so that the surface roughness Ra is 0.1 to 0.3 [nm] and the maximum height Rmax is 1.0 to 10.0 [nm]. ].
　ここで、金属酸化膜３を成膜することで磁気記録媒体用基板１の表面が平滑になるメカニズムについて図４を参照して説明する。図４は、本発明の実施形態に係る磁気記録媒体用基板の一部の断面を拡大した断面図である。 Here, the mechanism by which the surface of the magnetic recording medium substrate 1 is smoothed by forming the metal oxide film 3 will be described with reference to FIG. FIG. 4 is an enlarged cross-sectional view of a part of the cross section of the magnetic recording medium substrate according to the embodiment of the present invention.
　図４（ａ）に、ポリッシング工程後の基板２の表面２２を示す。基板２の表面２２には、溝状の研磨痕４が残存している。液相析出法によると、平衡反応による界面における微小なエネルギー差で膜の析出が発生する。そのため、液相析出法によって基板２の表面に金属酸化膜３を成膜すると、研磨痕４のような溝状の形状が形成された表面２２であっても、その形状に依存せずに、同じ成膜速さで金属酸化膜３を成膜することができる。そして、金属酸化膜３の形状は、基板２の表面２２の形状に追従する。例えば図４（ｂ）に示すように、基板２の表面２２には金属酸化膜３が形成されると、研磨痕４の内部にも金属酸化膜３は形成され、研磨痕４の形状に追従して、溝４１が金属酸化膜３上に形成される。 FIG. 4A shows the surface 22 of the substrate 2 after the polishing process. Groove-shaped polishing marks 4 remain on the surface 22 of the substrate 2. According to the liquid phase deposition method, film deposition occurs with a small energy difference at the interface due to the equilibrium reaction. Therefore, when the metal oxide film 3 is formed on the surface of the substrate 2 by the liquid phase deposition method, even if the surface 22 has a groove-like shape such as the polishing mark 4, it does not depend on the shape. The metal oxide film 3 can be formed at the same film formation speed. The shape of the metal oxide film 3 follows the shape of the surface 22 of the substrate 2. For example, as shown in FIG. 4B, when the metal oxide film 3 is formed on the surface 22 of the substrate 2, the metal oxide film 3 is also formed inside the polishing mark 4 and follows the shape of the polishing mark 4. Thus, the trench 41 is formed on the metal oxide film 3.
　さらに反応を進めると、図４（ｃ）に示すように基板２の表面２２に形成された溝状の形状は徐々にカバレージされて、表面に形成された溝４２の大きさは徐々に小さくなる。さらに反応を進めると、研磨痕４に起因する溝に金属酸化膜３が埋まって、磁気記録媒体用基板１の表面は平滑になる。このように、液相析出法によって基板２の表面に金属酸化膜３を成膜することで、磁気記録媒体用基板に求められている平滑性を得ることが可能となる。 As the reaction proceeds further, the groove-like shape formed on the surface 22 of the substrate 2 is gradually covered as shown in FIG. 4C, and the size of the groove 42 formed on the surface gradually decreases. . When the reaction is further advanced, the metal oxide film 3 is buried in the groove caused by the polishing mark 4, and the surface of the magnetic recording medium substrate 1 becomes smooth. Thus, by forming the metal oxide film 3 on the surface of the substrate 2 by the liquid phase deposition method, it is possible to obtain the smoothness required for the magnetic recording medium substrate.
　なお、研磨痕４の深さとほぼ同じ膜厚の金属酸化膜３を表面に成膜することにより、研磨痕４の形状はほぼカバレージされるため、基板２の平滑性に合わせて金属酸化膜３の成膜量を制御すれば良い。 Since the metal oxide film 3 having the same thickness as the depth of the polishing mark 4 is formed on the surface, the shape of the polishing mark 4 is substantially covered. Therefore, the metal oxide film 3 is matched to the smoothness of the substrate 2. The amount of film formation may be controlled.
　なお、金属酸化膜３として、ＳｉＯ２膜又はＴｉＯ２膜を成膜することが好ましい。金属としてＳｉ又はＴｉを用いることで、水溶液中における平衡反応を円滑に進めることができるため、ＳｉＯ２膜又はＴｉＯ２膜を比較的簡単に成膜することができるからである。 As the metal oxide film 3, it is preferable to form a SiO 2 film or a TiO 2 film. This is because the use of Si or Ti as the metal allows the equilibrium reaction in the aqueous solution to proceed smoothly, so that the SiO 2 film or the TiO 2 film can be formed relatively easily.
　以上の工程で作製された磁気記録媒体用基板１の表面に磁性膜を成膜することで、磁気記録媒体を作製する。すなわち、本実施形態に係る磁気記録媒体は、ガラス基板又はアルミニウム基板で構成される基板２の表面に金属酸化膜３が成膜され、その金属酸化膜３上に磁性膜が成膜された構成を有している。 A magnetic recording medium is produced by forming a magnetic film on the surface of the magnetic recording medium substrate 1 produced by the above steps. That is, the magnetic recording medium according to the present embodiment has a configuration in which the metal oxide film 3 is formed on the surface of the substrate 2 made of a glass substrate or an aluminum substrate, and the magnetic film is formed on the metal oxide film 3. have.
　また、磁気記録媒体用基板１の表面に軟磁性層を形成し、その軟磁性層上に中間層を形成し、その中間層上に磁性膜からなる記録層を形成しても良い。１例として、軟磁性層には厚さが５～２０［ｎｍ］のＣｏＺｒＮｂを用い、中間層には厚さが１０～２０［ｎｍ］のＰｔ－Ｃを用いる。 Alternatively, a soft magnetic layer may be formed on the surface of the magnetic recording medium substrate 1, an intermediate layer may be formed on the soft magnetic layer, and a recording layer made of a magnetic film may be formed on the intermediate layer. As an example, CoZrNb with a thickness of 5 to 20 [nm] is used for the soft magnetic layer, and Pt—C with a thickness of 10 to 20 [nm] is used for the intermediate layer.
　また、磁性膜には、１例として、厚さが１０～１５［ｎｍ］のＣｏＣｒＰｔ－ＳｉＯ２を用いる。これらの膜は、例えばスパッタリングによって成膜すれば良い。なお、基板２にアルミニウム基板を用いる場合、アルミニウム基板上にＮｉＰ層が形成され、そのＮｉＰ層上に金属酸化膜３が成膜されている。 For example, CoCrPt—SiO 2 having a thickness of 10 to 15 [nm] is used for the magnetic film. These films may be formed by sputtering, for example. When an aluminum substrate is used as the substrate 2, a NiP layer is formed on the aluminum substrate, and a metal oxide film 3 is formed on the NiP layer.
　次に、上述した実施形態の具体的な実施例について説明する。
（実施例１）
（基板２）
　実施例１では、基板２にプレス法で作製したアルミノシリケートガラス基板を用いた。基板２の寸法を以下に示す。 Next, specific examples of the above-described embodiment will be described.
Example 1
(Substrate 2)
In Example 1, an aluminosilicate glass substrate produced by a press method was used for the substrate 2. The dimensions of the substrate 2 are shown below.
　基板２の直径＝２．５インチ（６２．５［ｍｍ］）
　基板２の内径（貫通孔２１の径）＝２０［ｍｍ］
　基板２の厚さ＝０．６３５［ｍｍ］
（ポリッシング工程後の表面粗さＲａ）
　基板２は、上述した第１ラッピング工程、第２ラッピング工程、及びポリッシング工程が施された基板である。第１ラッピング工程及び第２ラッピング工程では、両面研磨機を用いて、ガラス基板に加わる定盤の加重及び定盤の回転数を調整して基板２の両面を研磨した。第１ラッピング工程及び第２ラッピング工程では、加重を６０［ｇ／ｃｍ２］とし、定盤の回転数を１０［ｒｐｍ］として研磨を行った。ポリッシング工程では、ラッピング工程で使用したダイヤモンドペレットに代えて、パットと研磨液を使用した。パットは硬度８０の発泡ウレタンを用いた。研磨材は、粒径が０．６［μｍ］の酸化セリウムを水に分散させてスラリー状にして用いた。定盤によるガラス基板への加重を、９０［ｇ／ｃｍ２］とし、定盤の回転数を２５［ｒｐｍ］とした。ポリッシング工程後の基板２の表面粗さＲａを、原子間力顕微鏡（ＡＦＭ）によって測定した。その結果、基板２の表面粗さＲａは０．８［ｎｍ］であり、最大高さＲｍａｘは３０．０［ｎｍ］であった。
（金属酸化膜３の成膜）
　実施例１では、金属酸化膜３としてのＳｉＯ２膜を基板２の表面に成膜した。具体的には、０．５［ｍｏｌ／ｌ］の（ＮＨ４）２ＳｉＦ６水溶液と、０．２［ｍｏｌ／ｌ］のＨ３ＢＯ３水溶液とを混合させた混合溶液に、ポリッシング工程後の基板２を常温で１時間浸漬させた。実施例１では、容量が５００［ｍｌ］の混合溶液に基板２を浸漬させた。なお、一度に複数の基板に対してＳｉＯ２膜を成膜する場合は、混合溶液の容量を大きくし、その混合溶液を循環させ、その混合溶液に基板２を浸漬させれば良い。
（成膜後の表面粗さＲａ）
　その浸漬により、基板２の表面に、厚さ３０［ｎｍ］のＳｉＯ２膜を成膜した。混合溶液中に基板２を浸漬させたため、基板２のすべての面に、ＳｉＯ２膜が成膜された。このＳｉＯ２膜が表面に成膜された基板が、上述した磁気記録媒体用基板１に相当する。ＳｉＯ２膜が成膜された基板の表面粗さＲａを測定した。その結果、表面粗さＲａは０．１［ｎｍ］になった。 The diameter of the substrate 2 = 2.5 inches (62.5 [mm])
Inner diameter of substrate 2 (diameter of through hole 21) = 20 [mm]
The thickness of the substrate 2 = 0.635 [mm]
(Surface roughness Ra after polishing process)
The substrate 2 is a substrate that has been subjected to the above-described first lapping step, second lapping step, and polishing step. In the first lapping process and the second lapping process, both surfaces of the substrate 2 were polished by adjusting the weight of the surface plate applied to the glass substrate and the rotation speed of the surface plate using a double-side polishing machine. In the first lapping step and the second lapping step, polishing was performed with a load of 60 [g / cm 2 ] and a rotation speed of the surface plate of 10 [rpm]. In the polishing process, a pad and a polishing liquid were used in place of the diamond pellets used in the lapping process. The pad was made of urethane foam having a hardness of 80. As the abrasive, cerium oxide having a particle size of 0.6 [μm] was dispersed in water and used as a slurry. The weight applied to the glass substrate by the surface plate was 90 [g / cm 2 ], and the rotation speed of the surface plate was 25 [rpm]. The surface roughness Ra of the substrate 2 after the polishing process was measured by an atomic force microscope (AFM). As a result, the surface roughness Ra of the substrate 2 was 0.8 [nm], and the maximum height Rmax was 30.0 [nm].
(Deposition of metal oxide film 3)
In Example 1, a SiO 2 film as the metal oxide film 3 was formed on the surface of the substrate 2. Specifically, a mixed solution obtained by mixing a 0.5 [mol / l] (NH 4 ) 2 SiF 6 aqueous solution and a 0.2 [mol / l] H 3 BO 3 aqueous solution into the mixed solution after the polishing step. The substrate 2 was immersed for 1 hour at room temperature. In Example 1, the substrate 2 was immersed in a mixed solution having a capacity of 500 [ml]. In the case of forming the SiO 2 film on a plurality of substrates at a time, the capacity of the mixed solution is increased, the mixed solution is circulated, it is sufficient to immerse the substrate 2 to the mixed solution.
(Surface roughness Ra after film formation)
By the immersion, a SiO 2 film having a thickness of 30 [nm] was formed on the surface of the substrate 2. Since the substrate 2 was immersed in the mixed solution, an SiO 2 film was formed on all surfaces of the substrate 2. The substrate on which the SiO 2 film is formed corresponds to the magnetic recording medium substrate 1 described above. The surface roughness Ra of the substrate on which the SiO 2 film was formed was measured. As a result, the surface roughness Ra was 0.1 [nm].
　以上のように、実施例１によると、ポリッシング工程後の基板２の表面に、液相析出法によってＳｉＯ２膜を成膜することで、第２ポリッシング工程を施さずに、磁気記録媒体用基板として十分な平滑面を有する基板を作製することができた。換言すると、第２ポリッシング工程を施さなくても、ＳｉＯ２膜を成膜することで、第２ポリッシング工程を施した場合と同程度の表面粗さＲａを得ることができた。
（実施例２）
　実施例２では、基板２にガラス基板を用い、ポリッシング工程の条件を変えた。具体的には、ポリッシング工程において、研磨量（研磨時間）を短縮した。その結果、基板２の表面粗さＲａは、５［ｎｍ］であり、最大高さＲｍａｘは、２００［ｎｍ］であった。そして、実施例１と同じ方法で、この基板２の表面に、厚さ２００［ｎｍ］のＳｉＯ２膜を成膜した。このＳｉＯ２膜が成膜された基板が、上述した磁気記録媒体用基板１に相当する。ＳｉＯ２膜が成膜された基板の表面粗さＲａは、０．１［ｎｍ］になった。 As described above, according to the first embodiment, the SiO 2 film is formed on the surface of the substrate 2 after the polishing process by the liquid phase deposition method, so that the second polishing process is not performed, and the magnetic recording medium substrate is performed. As a result, a substrate having a sufficiently smooth surface could be produced. In other words, even if the second polishing step is not performed, it is possible to obtain the same surface roughness Ra as when the second polishing step is performed by forming the SiO 2 film.
(Example 2)
In Example 2, a glass substrate was used as the substrate 2 and the polishing process conditions were changed. Specifically, the polishing amount (polishing time) was shortened in the polishing process. As a result, the surface roughness Ra of the substrate 2 was 5 [nm], and the maximum height Rmax was 200 [nm]. Then, a SiO 2 film having a thickness of 200 [nm] was formed on the surface of the substrate 2 by the same method as in Example 1. The substrate on which the SiO 2 film is formed corresponds to the magnetic recording medium substrate 1 described above. The surface roughness Ra of the substrate on which the SiO 2 film was formed was 0.1 [nm].
　以上のように、研磨痕の深さとほぼ同じ膜厚のＳｉＯ２膜を成膜することで、磁気記録媒体用基板１の表面を平滑にすることが可能となるため、ポリッシング工程における研磨量（研磨時間）を短縮することも可能となる。そのため、ポリッシングにおける表面粗さＲａの管理が容易となり、研磨コストを低減することが可能となる。
（実施例３）
　実施例３では、基板２にアルミニウム基板を用いた。基板２の寸法は、実施例１と同じであるため、説明を省略する。 As described above, since the surface of the magnetic recording medium substrate 1 can be smoothed by forming the SiO 2 film having the same film thickness as the depth of the polishing mark, the polishing amount in the polishing process ( It is also possible to shorten the polishing time. Therefore, it becomes easy to manage the surface roughness Ra in polishing, and the polishing cost can be reduced.
(Example 3)
In Example 3, an aluminum substrate was used as the substrate 2. Since the dimensions of the substrate 2 are the same as those of the first embodiment, description thereof is omitted.
　基板２の表面を研削し、表面にＮｉＰを無電解めっきで成膜した。この実施例３では、５［μｍ］のＮｉＰ層を成膜した。そして、ガラス基板に対する研磨と同様に、基板２上に成膜されたＮｉＰ層を研磨した。研磨後の基板２の表面粗さＲａは０．８［ｎｍ］であり、最大高さＲｍａｘは３０．０［ｎｍ］であった。 The surface of the substrate 2 was ground, and NiP was formed on the surface by electroless plating. In Example 3, a 5 μm NiP layer was formed. Then, the NiP layer formed on the substrate 2 was polished in the same manner as the polishing for the glass substrate. The surface roughness Ra of the substrate 2 after polishing was 0.8 [nm], and the maximum height Rmax was 30.0 [nm].
　その後、実施例１と同じ混合溶液に基板２を浸漬した。その結果、ＮｉＰ層上に厚さ３０［ｎｍ］のＳｉＯ２膜を成膜した。このＳｉＯ２膜が表面に成膜された基板が、上述した磁気記録媒体用基板１に相当する。ＳｉＯ２膜が成膜された基板の表面粗さＲａを測定した。その結果、表面粗さＲａは０．１［ｎｍ］になった。 Thereafter, the substrate 2 was immersed in the same mixed solution as in Example 1. As a result, a SiO 2 film having a thickness of 30 [nm] was formed on the NiP layer. The substrate on which the SiO 2 film is formed corresponds to the magnetic recording medium substrate 1 described above. The surface roughness Ra of the substrate on which the SiO 2 film was formed was measured. As a result, the surface roughness Ra was 0.1 [nm].
　以上のように、実施例２、３によると、実施例１と同様に、最終段階の研磨工程を行わなくても、磁気記録媒体用基板として十分な平滑面を有する基板を作製することができた。 As described above, according to Examples 2 and 3, as in Example 1, a substrate having a sufficiently smooth surface as a magnetic recording medium substrate can be produced without performing the final polishing step. It was.
　なお、上述した実施例１から実施例３においては、ポリッシング工程後における基板２の表面粗さＲａが０．８［ｎｍ］又は５［ｎｍ］であったが、表面粗さＲａがこれらの値以外であっても同じ効果を奏することができる。例えば、ポリッシング工程後における表面粗さＲａが０．３～５［ｎｍ］であれば、基板２上にＳｉＯ２膜を成膜することで、表面粗さＲａを０．１～０．３［ｎｍ］にすることができる。例えば、ポリッシング工程後における基板２の表面粗さＲａの大きさに応じて、混合溶液に基板２を浸漬させる時間を変えたり、混合溶液の濃度を調整したりすることで、表面粗さＲａを０．１～０．３［ｎｍ］にすることができる。 In Example 1 to Example 3 described above, the surface roughness Ra of the substrate 2 after the polishing process was 0.8 [nm] or 5 [nm]. Even if it is other than, the same effect can be produced. For example, if the surface roughness Ra after the polishing process is 0.3 to 5 [nm], the surface roughness Ra is set to 0.1 to 0.3 [nm] by forming a SiO 2 film on the substrate 2. nm]. For example, depending on the size of the surface roughness Ra of the substrate 2 after the polishing step, the surface roughness Ra can be reduced by changing the time during which the substrate 2 is immersed in the mixed solution or adjusting the concentration of the mixed solution. The thickness can be 0.1 to 0.3 [nm].
　なお、実施例１から実施例３においては、金属酸化膜３としてＳｉＯ２膜を用いたが、本発明に係る金属酸化膜はＳｉＯ２膜に限定されない。上述した複数の金属のうち、１種類又は２種類以上の成分を含む酸化膜を用いた場合も、ＳｉＯ２膜を用いた場合と同じ作用及び効果を奏することができる。例えば、混合溶液に基板２を浸漬させる時間を変えたり、混合溶液の濃度を調整したりすることで、表面粗さＲａを０．１～０．３［ｎｍ］にすることができる。 In the first to third embodiments, the SiO 2 film is used as the metal oxide film 3, but the metal oxide film according to the present invention is not limited to the SiO 2 film. Even when an oxide film containing one kind or two or more kinds of components among the plurality of metals described above is used, the same operation and effect as when the SiO 2 film is used can be obtained. For example, the surface roughness Ra can be set to 0.1 to 0.3 [nm] by changing the time for immersing the substrate 2 in the mixed solution or adjusting the concentration of the mixed solution.

Claims (7)

  1. 　円板状の基板の表面を研磨する研磨工程と、
    　前記研磨工程後の基板に対して、液相析出法によって表面に金属酸化膜を成膜して、磁気記録媒体用基板を製造する成膜工程と、
    　を含むことを特徴とする磁気記録媒体用基板の製造方法。     A polishing step for polishing the surface of the disk-shaped substrate;
    A film forming step of manufacturing a magnetic recording medium substrate by forming a metal oxide film on the surface by a liquid phase deposition method on the substrate after the polishing step;
    The manufacturing method of the board | substrate for magnetic recording media characterized by the above-mentioned.
  2. 　前記研磨工程では、表面粗さＲａが０．３～５［ｎｍ］になるまで、前記基板の表面を研磨することを特徴とする請求の範囲第１項に記載の磁気記録媒体用基板の製造方法。 2. The magnetic recording medium substrate according to claim 1, wherein in the polishing step, the surface of the substrate is polished until the surface roughness Ra becomes 0.3 to 5 [nm]. Method.
  3. 　前記金属酸化膜は、二酸化ケイ素の膜であることを特徴とする請求の範囲第１項又は第２項に記載の磁気記録媒体用基板の製造方法。 3. The method for manufacturing a substrate for a magnetic recording medium according to claim 1 or 2, wherein the metal oxide film is a silicon dioxide film.
  4. 　前記金属酸化膜は、Ｓｉ、Ｔｉ、Ｖ、Ｍｎ、Ｎｉ、Ｚｎ、Ｇｅ、Ｙ、Ｚｒ、Ｎｂ、Ｓｎ、Ｓｂ、Ｂａ、Ｔａ、及びＷの成分のうち、１種類又は２種類以上の成分を含む酸化膜であることを特徴とする請求の範囲第１項又は第２項に記載の磁気記録媒体用基板の製造方法。 The metal oxide film includes one or more components among Si, Ti, V, Mn, Ni, Zn, Ge, Y, Zr, Nb, Sn, Sb, Ba, Ta, and W components. 3. The method for manufacturing a substrate for a magnetic recording medium according to claim 1, wherein the substrate is an oxide film.
  5. 　前記基板は、ガラス基板又はアルミニウム基板であることを特徴とする請求の範囲第１項から第４項のいずれかに記載の磁気記録媒体用基板の製造方法。 The method for manufacturing a substrate for a magnetic recording medium according to any one of claims 1 to 4, wherein the substrate is a glass substrate or an aluminum substrate.
  6. 　前記成膜工程では、水溶液中に前記研磨工程後の基板を浸漬させ、前記水溶液中において金属フルオロ錯体が加水分解することにより、前記研磨工程後の基板の表面に前記金属酸化膜を成膜することを特徴とする請求の範囲第１項から第５項のいずれかに記載の磁気記録媒体用基板の製造方法。 In the film formation step, the metal oxide film is formed on the surface of the substrate after the polishing step by immersing the substrate after the polishing step in an aqueous solution and hydrolyzing the metal fluoro complex in the aqueous solution. The method for manufacturing a substrate for a magnetic recording medium according to any one of claims 1 to 5, wherein:
  7. 　表面粗さＲａが０．３～５［ｎｍ］である円板状の基板と、
    　前記基板の表面に形成された金属酸化膜と、
    　前記金属酸化膜上に形成された磁性膜と、
    　を有することを特徴とする磁気記録媒体。     A disk-shaped substrate having a surface roughness Ra of 0.3 to 5 [nm];
    A metal oxide film formed on the surface of the substrate;
    A magnetic film formed on the metal oxide film;
    A magnetic recording medium comprising:
PCT/JP2009/050293 2008-01-29 2009-01-13 Process for production of substrate for magnetic recording medium, and magnetic recording medium WO2009096217A1 (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113362863A (en) * 2017-06-30 2021-09-07 Hoya株式会社 Magnetic disk substrate and magnetic disk
TWI755466B (en) * 2016-12-28 2022-02-21 日商東洋鋼鈑股份有限公司 Substrate for hard disk and hard disk device using the same

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001014662A (en) * 1999-06-28 2001-01-19 Hitachi Maxell Ltd Manufacture of magnetic disk
JP2002222514A (en) * 2001-01-24 2002-08-09 Fuji Electric Co Ltd Substrate for information recording medium, manufacturing method therefor and information magnetic recording medium
JP2005277118A (en) * 2004-03-25 2005-10-06 New Industry Research Organization Fine structure capacitor and its manufacturing method, high-density recording medium, and its manufacturing method

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005289767A (en) * 2004-04-02 2005-10-20 Nippon Sheet Glass Co Ltd Method of manufacturing metal oxide coating film

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001014662A (en) * 1999-06-28 2001-01-19 Hitachi Maxell Ltd Manufacture of magnetic disk
JP2002222514A (en) * 2001-01-24 2002-08-09 Fuji Electric Co Ltd Substrate for information recording medium, manufacturing method therefor and information magnetic recording medium
JP2005277118A (en) * 2004-03-25 2005-10-06 New Industry Research Organization Fine structure capacitor and its manufacturing method, high-density recording medium, and its manufacturing method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI755466B (en) * 2016-12-28 2022-02-21 日商東洋鋼鈑股份有限公司 Substrate for hard disk and hard disk device using the same
CN113362863A (en) * 2017-06-30 2021-09-07 Hoya株式会社 Magnetic disk substrate and magnetic disk
CN113362863B (en) * 2017-06-30 2022-09-30 Hoya株式会社 Magnetic disk substrate and magnetic disk
US11694718B2 (en) 2017-06-30 2023-07-04 Hoya Corporation Substrate for magnetic disk, magnetic disk, and hard disk drive apparatus

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