JP2586521B2 - Magnetic recording medium and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium for magnetically recording data and a method for manufacturing the same, and in particular, realizes high track density (narrow track) by perpendicular magnetic recording. And a method of manufacturing the same.

[Conventional technology]

Increasing the recording density of magnetic recording media is a constant trend in the art. A conventional magnetic recording medium generally performs recording and reproduction by magnetizing in the longitudinal direction of the recording medium. However, the recording density is limited by the influence of the demagnetizing field as the density increases, and the recording density can be further increased. A perpendicular magnetic recording method in which magnetization is performed in a direction perpendicular to the surface has been proposed, and a higher density of one digit or more than the conventional recording density has been achieved.

Such a perpendicular magnetic recording medium has an alloy thin film typified by CoCr formed by a sputtering method or a vacuum evaporation method. When a perpendicular magnetic head is used, it has a two-layer structure in which a soft magnetic layer such as permalloy (FeNi) is formed below the CoCr layer in order to improve the recording and reproducing efficiency. By providing magnetic anisotropy in the perpendicular direction of the magnetic recording medium (hereinafter, also simply referred to as “medium”) and eliminating the demagnetizing field which adversely affects high-density recording in in-plane recording, the recording density characteristics are improved. Trying to improve.

[Problems to be solved by the present invention]

The conventional magnetic recording medium described above has a disadvantage that crosstalk and noise remaining due to track deviation increase due to narrowing of track, and that a good S / N cannot be obtained. Technology and head processing technology, which has the disadvantage of increasing the manufacturing cost.

[Means for solving the problem]

According to the present invention, a substrate in which the surface roughness of the guard band portion is larger than the surface roughness of the data track portion is prepared, and a soft magnetic film, a perpendicular magnetization film, and a protective film are sequentially formed on the substrate by sputtering or vacuum evaporation. By providing a magnetic recording medium in which the perpendicular magnetic anisotropy of the guard band portion is made smaller than the perpendicular magnetic anisotropy of the data track portion and a method of manufacturing the same, the above-mentioned disadvantages have been solved.

[Configuration of the invention]

By forming a perpendicular magnetization film on a substrate (disk, tape, film) in which the surface roughness of the guard band portion of the magnetic recording medium is larger than the surface roughness of the data track portion,
The perpendicular magnetic anisotropy of the guard band portion is made much smaller than the perpendicular magnetic anisotropy of the data track portion, and the crosstalk characteristics are improved. The perpendicular magnetic anisotropy is largely caused by the roughness of the substrate surface. If the surface roughness becomes extremely large, the film becomes not a perpendicular magnetization film but an in-plane magnetization film. By utilizing this property, a medium that is hardly perpendicularly recorded on the guard band portion is provided as much as possible.

In order to obtain a substrate having a guard band portion with a predetermined surface roughness, a known method such as laser recording is used to perform electroplating from a master plate on which surface roughness (irregularities) having a required depth and pattern interval is formed. Using a duplicate stamper, a film such as PET (polyethylene terephthalate), PC (polycarbonate), PS (polysulfan) or P
What is necessary is just to transfer to a board | substrate of C, PS, acrylic, etc. with a photopolymer. Alternatively, a thermoplastic resin such as PVC (polyvinyl chloride), PC, or acrylic may be compression-molded or injection-molded by the stamper. Even if the medium is a tape, a substrate having a guard band portion with a predetermined surface roughness can be obtained by a method similar to the above method. The surface roughness is Ra100 ~ 100
0Å is desirable.

〔Example〕

Hereinafter, a specific embodiment of the magnetic recording medium of the present invention and a method of manufacturing the same will be described with reference to FIG. As shown in FIG. 1 (A), a stamper 1 having a predetermined surface roughness is provided on a guard band portion 1a and a PE having a width of about 50 μm.
Photopolymer 3 is introduced between T (polyethylene terephthalate) 2 and pressurized (FIG. 2 (B)), and is irradiated with ultraviolet rays (FIG. 2 (C)) to obtain a surface roughness Ra as shown in FIG. About 80
A film substrate 4 having a 0 ° guard band 1a was formed. On top of this, a soft magnetic film (for example, a 0.5 μm-thick FeNi film) 5 and a perpendicular magnetic film (the same as shown in FIG.
A 0.2 μm CoCr film) 6 and a protective film (200 ° carbon film) 7 were formed. The measured anisotropy field H _K of the medium prepared by the above method, the guard band portion 1a
CoCr film is 0.8KOe, CoCr film of data track part 1b is 4.0KOe
Met. That is, the guard band portion 1a is about 1/5 of the data track portion 1b.

As a result of examining the recording / reproducing characteristics using a main pole excitation type head having a main pole film of CoZrTa 0.3 μm, the recording density D ₅₀ at which the solitary wave output is 1/2 of the solitary wave output on the guard band section 1a is ₅₀ KBPI, and the data track section is a 160KBPI in 1b, the reproduction output of the guard band portion 1a was 1/3 of the data track portion 1b at D ₅₀ is 30KBPI. Therefore, it was found that at 50 KBPI or more, the reproduction output from the guard band unit 1a was low, and good crosstalk characteristics were obtained.

In the above description, as a method of forming the film substrate 4, a photopolymer 3 is introduced between the stamper 1 having a predetermined surface roughness in the guard band portion 1a and PET2 having a width of about 50 μm, and the pressure is applied to the film. Although it has been described that a substrate having a predetermined surface roughness is formed by irradiating and curing the photopolymer 3, the present invention is not limited to this, and a predetermined surface roughness can be obtained by compression molding or injection molding a thermoplastic resin. A magnetic recording medium obtained by forming a soft magnetic film, a perpendicular magnetization film, and a protective film on the substrate thus formed by a sputtering method or a vacuum evaporation method may be used. The characteristics were almost the same as those of the medium prepared by the above method.

〔effect〕

According to the present invention, the surface roughness of the guard band portion between the adjacent data tracks of the magnetic film is made larger than the surface roughness of the data portion by the above method, so that the perpendicular magnetic anisotropy of the guard band portion is reduced in the data track portion. A magnetic recording medium smaller than the perpendicular magnetic anisotropy can be manufactured. As a result, in the recording medium, crosstalk from an adjacent track can be reduced. Crosstalk characteristics are obtained and stable S / N
It has the characteristic that characteristics can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram of an embodiment for producing a substrate having a guard band portion having a predetermined surface roughness in a method of manufacturing a magnetic recording medium according to the present invention, and FIG. FIG. 3 is a partial perspective view of a recording medium substrate, and FIG. 3 is a partial sectional view of the magnetic recording medium of the present invention. DESCRIPTION OF SYMBOLS 1 ... Stamper, 1a ... Guard band part, 1b ... Data track part, 2 ... PET (polyethylene terephthalate), 3 ... Photopolymer, 4 ... Film substrate, 5 ...
... soft magnetic film, 6 ... perpendicular magnetization film, 7 ... protective film.

Claims (4)

(57) [Claims] 1. A method according to claim 1, wherein the surface roughness of the guard band portion formed on the data recording surface of the substrate is made larger than the surface roughness of the data track portion, and then a perpendicular magnetization film is formed on the data recording surface of the substrate. Thus, the perpendicular magnetic anisotropy of the guard band portion is made smaller than the perpendicular magnetic anisotropy of the data track portion. 2. A substrate having a data recording surface in which the surface roughness of the guard band portion is larger than the surface roughness of the data track portion, and a soft magnetic film, a perpendicular magnetization film, and a protective film are formed on the substrate by a sputtering method. A method for manufacturing a magnetic recording medium, wherein the magnetic recording medium is sequentially formed by a vacuum deposition method. 3. The manufacturing of a magnetic recording medium according to claim 2, wherein the surface roughness of the guard band portion of the substrate is made larger than the surface roughness of the data track portion by curing the photopolymer with ultraviolet rays. Method. 4. The magnetic recording according to claim 2, wherein the surface roughness of the guard band portion of the substrate is made larger than the surface roughness of the data track portion by compression molding or injection molding of a thermoplastic resin. The method of manufacturing the medium.