JP2000067431A - Production of information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make preventable the increase of the thickness distribution of coating layers formed on information recording media by disposing terminal plates having the substantially same size as the media at the outsides of both ends of the media when the surfaces of the media are coated with a coating fluid. SOLUTION: Terminal plates 5 are disposed at the outsides of both ends of information recording media 4 so as to prevent the vibration of the outer surfaces of the media at both ends. A discoid nonmagnetic substrate of Al, its alloy, glass or the like is used as the substrate of each of the media 4. After working to a prescribed thickness, the surface of the substrate is mirror-polished and a nonmagnetic metallic film is formed. An underlayer is then formed and a magnetic layer is formed on the underlayer by sputtering or other method. A layer of a Co alloy such as Co-Cr, Co-Ni, Co-Cr-X, Co-Ni-X or Co-W-X is suitable for use as the magnetic layer. The terminal plates 5 have the substantially same shape as the media 4 and the interval between each of the terminal plates 5 and the adjacent medium is almost equal to the interval between the media.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing an information recording medium. More specifically, the present invention relates to a method for manufacturing an information recording medium that improves the in-plane film thickness distribution of a coating layer provided on the surface of the information recording medium.

[0002]

2. Description of the Related Art In recent years, with the development of information processing technologies such as computers, magnetic recording media such as magnetic disks, and optical recording media such as magneto-optical disks, phase-change optical disks, and DVD-ROMs have been used as external storage devices. Used. Conventionally, as a magnetic recording medium, a non-magnetic substrate obtained by subjecting an aluminum alloy substrate to a non-magnetic plating treatment such as alumite treatment or Ni-P plating is used for forming a Cr or Cr alloy, Ni-
An undercoat layer of an Al alloy or the like, a magnetic layer of a Co-based alloy, a carbonaceous protective layer, and a lubricant are used.

[0003] With the increase in the density of the magnetic disk, the distance between the magnetic disk and the magnetic head, that is, the flying height is becoming smaller and smaller, and recently, 0.10 µm or less is required. In recent years, in order to further increase the density of optical recording media, the distance between the medium and the optical head is becoming smaller,
Recently, attempts have been made to perform recording / reproducing on a magneto-optical disk coated with a lubricant after providing a reflective layer, a magnetic layer, and a protective layer on a plastic substrate using a floating type head or a contact type head having a flying height of 3 μm or less. ing.

[0004]

When recording / reproducing is performed using such a floating head, when the disk is started, an adhesion phenomenon occurs in which the head is fixed to the disk surface and does not fly, or during operation, the head and the head cannot be lifted. Normal rotation may be hindered by contact with the disk due to frictional resistance. In particular, the size of the magnetic disk is also being reduced in parallel with the above-mentioned high density (low flying height), and the motor for rotating the spindle is becoming smaller. As a result, the torque of the motor becomes insufficient, and there is a possibility that the magnetic head is stuck to the surface of the magnetic disk and does not fly at the time of start-up. In addition, the magnetic head may come into contact with the magnetic disk during operation, and normal rotation may be hindered due to frictional resistance. As a result of the study by the present inventors, it has been found that when the in-plane thickness unevenness of the lubricating layer provided on the protective layer of the disk substrate is large, the adhesion phenomenon is also large. As means for preventing the occurrence of these phenomena, in the case of a magnetic disk, a surface treatment called texture processing for forming fine irregularities on the substrate surface has been performed, but the adhesion phenomenon could not always be prevented. The present invention provides a method for improving the in-plane film thickness distribution of a coating layer on the medium surface, particularly, a method for improving the in-plane film thickness distribution of a lubricating layer on the protective layer surface, in order to solve such a problem relating to the information recording medium. To provide.

[0005]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have made intensive studies on a method for improving the in-plane film thickness distribution of a coating layer on the surface of an information recording medium. In the step of applying a coating liquid on the surface of the information recording medium by immersing the medium in a coating liquid tank with a plurality of mediums attached, the in-plane film thickness distribution outside the media at both ends of the plurality of media may be significantly increased. Do you get it. It has been found that by providing an end plate having substantially the same size as the substrate outside the medium at both ends, it is possible to prevent an increase in the film thickness distribution of the coating layer on the medium, and to complete the present invention. Reached. That is, the present invention provides a method of applying a coating liquid on the surface of an information recording medium by attaching a plurality of information recording media to a disk support and immersing the same in a coating liquid and pulling up the same. A method for manufacturing an information recording medium, comprising attaching an end plate having substantially the same size as the medium.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
Generally, there are a spin coating method, a dipping method, and the like as a method of forming a coating layer. In the present invention, a dipping method is used in which a disk is dipped in a coating liquid tank and then pulled up to form a coating layer on the medium surface. FIG. 1 shows an example of the coating apparatus according to the present invention. The following reasons are considered as causes for the in-plane film thickness distribution outside the media at both ends of the plurality of media to become significantly large. The building and the floor on which these devices are installed vibrate due to various factors in the environment, and the vibration is transmitted, so that the coating solution tank 1 and the disk support 3 are also constantly vibrating. Therefore, it is inevitable that the coating liquid 2 and the information recording medium 4 vibrate minutely. here,
It is considered that the vibration occurring between the information recording media 4 has a small amplitude because the distance between the media is small, and the amplitude is constant and does not fluctuate because the distance is always constant. On the other hand, the outer surfaces of the media at both ends face the coating liquid tank 1, and since the distance is large, a wave having a large amplitude is easily generated. Also, when the disk support 3 is immersed or pulled up, large vibrations are generated, so that a wave is more likely to be generated, and furthermore, it fluctuates easily. For this reason, it is considered that the in-plane film thickness distribution significantly increases on the outer surfaces of the media at both ends. In order to make the coating liquid tank non-vibrating so that vibration from the building is not transmitted at all, a very large cost is required. Therefore,
In the present invention, it is an object of the present invention to provide end plates on both sides of the information recording medium 4 so as to eliminate vibrations on the outer surfaces of the medium at both ends. The end plate has substantially the same shape as the information recording medium 4. The distance between the medium and the end plate is preferably substantially the same as the distance between the mediums. The material of the end plate is preferably a material having substantially the same vibration characteristics as the medium, and more preferably the same material as the substrate. The type of the coating liquid is not limited, but is particularly effective when applied to the formation of a lubricating layer.
As described above, in an information recording medium on which recording and reproduction are performed by a flying head or a contact head, unevenness of the in-plane film thickness of the lubricating layer becomes a problem. The information recording medium according to the present invention may be a magnetic recording medium such as a magnetic disk, a magneto-optical disk, a phase change optical disk,
An optical recording medium such as a VD-ROM may be used, but a medium in which a magnetic layer and a protective layer are provided on a substrate, that is, a magnetic recording medium and a magneto-optical recording medium are particularly preferable. The magnetic recording medium may have any other configuration as long as it has at least a magnetic layer and a protective layer on a substrate, but usually has an underlayer, a magnetic layer, and a protective layer on the substrate in order.

As the substrate of the magnetic recording medium in the present invention, a disk-shaped non-magnetic substrate made of aluminum, aluminum alloy, glass or the like is used. Normally, these non-magnetic substrates are processed to a predetermined thickness, mirror-finished on the surface thereof, and then subjected to a non-magnetic metal, for example, Ni-P alloy, Ni-C
Approximately 5-20 μm of u-P alloy etc. by electroless plating
It is used after forming a surface layer by forming a film with a thickness of m.
The surface layer formed on the substrate in this manner is subjected to texture processing as necessary, and fine grooves or irregularities are processed and formed with high precision to obtain a surface processed layer finished to a specific surface roughness. By this texture processing, adsorption between the magnetic head and the magnetic recording medium can be prevented, and CSS characteristics are improved.
Further, the magnetic anisotropy is improved.

Further, after forming a base layer on the surface processing layer, a magnetic layer is formed by adhesion. The underlayer is formed, for example, by forming a chromium or Cr alloy or Ni-Al alloy underlayer having a thickness of about 50 to 2000 ° by a sputtering method. Co-Cr, Co-Ni, Co-Cr-X, C
A magnetic layer of a Co-based alloy represented by o-Ni-X, Co-WX or the like is preferable. Here, X is Li, S
i, Ca, Ti, V, Cr, Ni, As, Y, Zr, N
b, Mo, Ru, Rh, Ag, Sb, Hf, Ta, W,
Re, Os, Ir, Pt, Au, La, Ce, Pr, N
One or more elements selected from the group consisting of d, Pm, Sm and Eu. The metal magnetic layer made of such a Co-based alloy is formed on the base layer of the substrate by means such as sputtering. The thickness of the metal magnetic layer is usually in the range of 50 to 600 °.

The protective layer includes a carbon film, a hydrogenated carbon film, a nitrogenated carbon film, a carbonized film such as TiC and SiC, SiN,
It is composed of a nitride film such as TiN, an oxide film such as SiO, Al ₂ O ₃ , ZrO, etc., and particularly preferably a carbon film, a hydrogenated carbon film and a nitrogenated carbon film.
It is formed by a D method, a sputtering method, an ion plating method, a wet method, or the like.

[0010] For example, the hydrogenated carbon film is not particularly limited as long as it is a film containing hydrogen and carbon. For example, sputtering is performed in a plasma containing a rare gas and hydrogen gas with carbon as a target. It is formed by doing. As a target used here, diamond-like, graphite-like, or amorphous carbon is used.

Examples of the rare gas include argon, helium, neon, xenon, radon, and krypton. Of these, argon is particularly preferably used. The content of hydrogen gas in a sputtering atmosphere containing a rare gas such as argon gas and hydrogen gas is usually 2 to 2 times.
0 volume%, desirably in the range of 5 to 10 volume%. As the sputtering method, a DC magnetron sputtering method is usually employed, but a high-frequency magnetron sputtering method can also be used.

The pressure in the chamber during sputtering is generally 0.5 to 20 mTorr, preferably 1 to 1 mTorr.
0 mTorr, and the temperature of the substrate is usually 300 ° C. or lower, preferably in the range of room temperature to 250 ° C. The distance between the substrate and the target, the sputtering time, the input power, and the like are appropriately determined according to the thickness of the hydrogenated carbon protective layer to be formed. The thickness of the hydrogenated carbon protective layer is usually 5
It is in the range of 0-1000 °, preferably 100-600 °.

A lubricating layer is provided on the surface of the protective layer.
Preferably, the thickness of the lubricating layer is in the range of about 15-50 °. Further, a heat treatment may be performed after the formation of the lubricating layer. The heating temperature is 50 ° C. or higher, but may be appropriately selected within a range lower than the decomposition temperature of the lubricant.

As the lubricant, a fluorine liquid lubricant is preferable. In particular, compounds having a hydroxyl group at the terminal or side chain and having a fluorocarbon skeleton in the molecular skeleton, for example, perfluorocarboxylic acid ester, perfluorothiol carboxylic acid ester, perfluorodicarboxylic acid ester, perfluorocarboxylic acid perfluorocarboxylic acid Alkyl ester, perfluorobenzoic acid ester, carboxylic acid perfluoroalkyl ester, dicarboxylic acid perfluoroalkyl ester, carboxylic acid perfluoroalkoxyalkyl ester, perfluorocarboxylic acid amide, perfluoropolyether, perfluoropolyethercarboxylic acid, Fluoropolyether alcohol, perfluoropolyetherester, and the like can be used. As such a lubricant, for example, Ausimo
Fomblin-Z-DOL (trade name), F
omblin-Z-Tetraol (trade name) and the like. On the other hand, a resin substrate provided with pits and grooves is used for the optical recording medium. Examples of the resin include an acrylic resin, a polyolefin resin such as a norbornene-based resin, a liquid crystal polymer, and a polycarbonate. Examples of the resin include polymethyl methacrylate (PMMA). , ARTON (Nippon Synthetic Rubber Co., Ltd.)
Norbornene-based ester-substituted cyclic olefin ring-opening polymer hydrogenated product), ZEONEX (Nippon Zeon Co., Ltd. norbornene-based cyclic olefin ring-opening polymer hydrogenated product), aromatic polyester-based liquid crystal polymer, polycarbonate, and the like. Based on a stamper provided with pits / grooves, pits / grooves are transferred and formed by injection molding, injection compression molding, radiation curing or the like using these resins to form a resin substrate. Unlike a glass, metal, ceramic, or the like, by using a resin, fine pits or grooves having a width or length of 2 μm or less and a depth of 100 nm or less can be formed accurately and at low cost. The thickness of the substrate is generally about 0.4 to 2 mm. If the thickness is too thin, the substrate is bent by its own weight and it is difficult to obtain flatness, but if it exceeds 2 mm, there is no great difference in strength.
As the optical recording layer formed on the substrate, various types can be used, for example, a magneto-optical recording layer, a phase-change recording layer,
A dye type recording layer is used. The layer configuration is not particularly limited, and various layer configurations can be adopted. As the magneto-optical recording layer, for example, TbFe, TbFeCo, Tb
An amorphous magnetic layer of a rare earth such as bCo, GdFeCo, DyTbFeCo and a transition metal, a polycrystalline perpendicular magnetization layer of MnBi, MnCuBi or the like, a Pt / Co multilayer film or the like is used. The magneto-optical recording layer may be a single layer, or GdTbFe / TbF in order to enable overwriting and MSR.
As shown in e, two or more magnetic layers may be stacked and used. Examples of the phase-change recording layer include GeSbTe and InSb.
Compounds such as Te, AgSbTe and AgInSbTe can be used. Preferably, ｛(Sb ₂ Te ₃ ) _1-x (G
_{eTe) x} 1-y Sb} y (0.2 <x <0.9,0 ≦ y <
0.1) In the alloy and the ternary alloy, up to about 10 atomic% of In, Ga, Zn, Sn, Si, Cu, Au, Ag, P
d, Pt, Pb, Cr, Co, O, S, Se, Ta, N
An alloy thin film containing at least one of b and V is mentioned. Alternatively, a material capable overwriting at a high speed, as the main component Sb ₇₀ Te ₃₀ eutectic point near the SbTe alloy, MSbTe (M = In, Ga , Zn, Ge, S
n, Si, Cu, Au, Ag, Pd, Pt, Pb, C
An alloy thin film of at least one of r, Co, O, S, Se, Ta, Nb, and V) is preferable. On the optical recording layer, a transparent intermediate layer having properties such as weather resistance, high hardness and high lubricity is provided. The material of the intermediate layer is selected in consideration of these properties.
A dielectric is preferable in terms of weather resistance and high hardness. As the dielectric, metal oxide, nitride, chalcogenide, carbide, fluoride, a mixture thereof, and the like are used. Al ₂ O ₃ , Ta ₂ O ₅ , SiO ₂ , Si
O, a metal oxide such as TiO ₂ alone or a mixture thereof,
Alternatively, a composite oxide of Al-Ta-O or the like can be given. Examples of the metal nitride include silicon nitride and aluminum nitride. As chalcogenides, ZnS, ZnS
II-V such as chalcogenide zinc such as e, CdS and CdSe
Group compounds, rare earth sulfides such as La ₂ S ₃ and Ce ₂ S ₃ , Ta
S ₂ , MgS, CaS and the like can be mentioned. Zinc chalcogenide is chemically stable, and among them, ZnS is particularly preferable because of its low toxicity. Examples of a method for forming these dielectric layers include vapor deposition and sputtering, and sputtering is more preferred. Materials with excellent lubricity include carbon film, hydrogenated carbon film, nitrogenated carbon film, TiC, S
carbide film such as iC, nitride film such as SiN and TiN, SiO,
It is composed of an oxide film such as Al ₂ O ₃ or ZrO or the like, and is usually formed by a sputtering method or the like. More preferred are a carbon film, a hydrogenated carbon film and a nitrogenated carbon film. The hydrogenated carbon film is not particularly limited as long as it contains hydrogen and carbon, and is not particularly limited. For example, a carbon target is used, and a sputtering gas (usually, an inert gas such as argon is used). It can be formed by a method of sputtering in a plasma containing hydrogen gas. The nitrogenated carbon film may be a film containing nitrogen and carbon, and is not particularly limited. For example, using a carbon target, a sputtering gas and a nitrogen gas, a nitrogen monoxide gas, a nitrogen dioxide gas, an ammonia gas It can be formed by sputtering in a plasma containing a gas containing nitrogen such as nitrogen or a gas containing nitrogen gas such as air. For example, when air is used, the content of air in the sputtering atmosphere is usually 2 to 20% by volume. Further, for example, a hydrogenated and nitrogenated carbon film can be formed by simultaneously mixing a hydrogen gas and a nitrogen (containing) gas into a sputtering gas. The intermediate layer has a role as a protective layer and a lubricating layer, but may have a plurality of layers. For example, when a protective layer having high weather resistance and high hardness is provided on the side in contact with the recording layer, and a lubricating layer having excellent lubricity is provided on the side in contact with the lubricating layer, both excellent properties can be obtained as a whole, which is preferable. . As the layer in contact with the magneto-optical recording layer, silicon nitride, SiO ₂ , Ta ₂ O ₅ or the like is preferably used. As a layer in contact with the phase-change recording layer, a mixture of ZnS and a metal oxide is preferably used.
Preferably, a reflective layer is provided between the substrate and the recording layer. As the reflective layer, a metal or an alloy having a high reflectance is used, for example, Al, Ag, Au, Cu, or an alloy containing these as a main component. Further, a transparent intermediate layer may be provided between the substrate or the reflective layer and the recording layer for the purpose of interfering and amplifying light and protecting the recording layer. As the material, the above-described dielectric or the like is preferably used. The lubricant may be the same as that used for the magnetic disk, but is preferably perfluoropolyether having an ester bond, dialkylamidocarboxylic acid, perchloropolyether, stearic acid, sodium stearate, phosphate ester, or the like. The ester bond may be located anywhere in the molecule, but it is more preferable to have an ester bond functional group at the end, since the movable portion in the molecule becomes longer and lubricity is easily obtained. Especially in the main chain
Having a C _a F _2a O-unit (where a is an integer of 1 to 4);
Perfluoropolyethers having a terminal functional group of an ester bond are preferred. For example, Audimont Fom
Blin-Z-DEAL is a polymer of CF ₂ CF ₂ O and CF ₂ O, has a linear structure, and has an ester group —COOR at both ends.
(Where R represents an alkyl group which may be substituted with fluorine). Also, Daikin Industries' Demn
The um type (SP or SY) is a homopolymer of hexafluoropropylene oxide with an ester group at one end.
COOR (where R represents an alkyl group which may be substituted with fluorine). The molecular weight of the lubricant is 100
It is preferably in the range of 10,000 to 10,000. If the molecular weight is low, the vapor pressure is generally high, evaporates little by little after coating, and moves away from the desired film thickness with time. Conversely, when the molecular weight is high, the viscosity is generally high, and the desired lubricity may not be obtained. As a solvent for dissolving these, for example, a fluorocarbon type, alcohol type, hydrocarbon type, ketone type, ether type, fluorine type, aromatic type, etc. are used. The coating thickness of the lubricant is preferably in the range of 1 to 20 nm. If it is outside this range, that is, thin,
Although the desired lubricity cannot be obtained, even if the thickness is too large, lubricity exceeding a certain level cannot be obtained, and excess lubricant moves to the outer circumference side with the rotation of the disk, causing a film thickness distribution on the inner and outer circumferences Easier to do.

[0015]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the invention. The magnetic disks used in the examples and comparative examples were manufactured as follows. A 3.5-inch aluminum alloy substrate coated with NiP plating by electroless plating, an underlayer mainly composed of Cr by sputtering,
A magnetic layer mainly composed of CoNiCr and a hydrogenated carbon protective layer were formed. As a lubricant, Ausimont
Using Fomblin-Z-DOL-2000 manufactured by
A solution dissolved in hydrofluoroether (trade name: HFE7200, manufactured by Sumitomo 3M Limited) was used.

(Embodiment) Using the coating apparatus shown in FIG.
Five magnetic disks were attached to the disk support 3 at regular intervals, and end plates (dummy disks) having the same shape and material as the magnetic disks were attached to both ends at the same intervals as the intervals between the magnetic disks. After this was immersed in the lubricant solution tank 1 and pulled up, the in-plane film thickness distribution of the lubricating layer formed on the disk was measured.
It was in the range of 80 °. The thickness distribution of the lubricating layer was measured as follows. 0 °, 90 °, 180 °, 2 rounds with a radius of 35 mm from the center of the 3.5-inch magnetic disk
Measurement is performed at four points of 70 °, and the maximum value (Max) and the minimum value (M
in) was calculated. (Comparative Example) The in-plane film thickness distribution of the lubricating layer formed on the disk was measured under the same conditions as in the example except that the end plates were not attached to both ends of the disk support 3. It became. Note that the in-plane film thickness distribution needs to be suppressed to 5 ° or less. 2 by attaching the end plate
It can be seen that five disks can completely maintain the same conditions in the lubricant solution, and a uniform film thickness distribution can be obtained.

[0017]

According to the method for manufacturing an information recording medium of the present invention, it is possible to inexpensively prevent an increase in the film thickness distribution of a coating layer on a medium. Can be uniformly provided, and when recording and reproduction are performed using a floating type head, it is possible to prevent the occurrence of a problem due to an adhesion phenomenon between the disk and the head or frictional resistance.

[0018]

[Brief description of the drawings]

FIG. 1 is an explanatory view of a coating apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 coating liquid tank 2 coating liquid 3 disk support 4 information recording medium 5 end plate

Claims (5)

[Claims] When a plurality of information recording media are mounted on a disk support and are immersed in a coating solution and lifted up to apply the coating solution to the surface of the information recording media, media are provided on both outer sides of both ends of the plurality of information recording media. A method of manufacturing an information recording medium, comprising attaching an end plate having substantially the same size as that of the information recording medium. 2. The method according to claim 1, wherein the end plate is made of a material having substantially the same vibration characteristics as a substrate of the information recording medium. 3. The method according to claim 2, wherein the end plate is made of the same material as the substrate of the information recording medium. 4. The method for manufacturing an information recording medium according to claim 1, wherein the coating liquid is a lubricant solution. 5. The method for manufacturing an information recording medium according to claim 1, wherein the information recording medium has a magnetic layer and a protective layer provided on a substrate.