JP2621616B2 - Method for manufacturing thin-film magnetic recording medium - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin-film magnetic recording medium used in a fixed magnetic disk device which is one of external storage devices of an information processing device such as a computer.

[Conventional technology]

Thin-film magnetic recording media (hereinafter, also simply referred to as media)
Generally, a non-magnetic plate made of an Al alloy or the like is provided with a required parallelism,
Finish to flatness and surface roughness, apply alumite treatment or Ni-P alloy electroless plating treatment to the surface to form a surface layer, polish the surface to the required roughness, wash and clean the non-magnetic substrate Then, this non-magnetic substrate is immersed and stored in still pure water, sequentially taken out and subjected to precision cleaning, and subsequently, on this non-magnetic substrate, is made of, for example, Cr for enhancing magnetism by a sputtering film forming method. Nonmagnetic metal underlayer, Co
A continuous thin-film magnetic layer consisting of a ferromagnetic metal such as an alloy is sequentially formed, and a thin film of C, SiO ₂ or the like is formed thereon as a hard protective film by a sputtering film forming method, a spin coating method, etc. It is manufactured by applying a liquid lubricant for improving the lubrication and wear resistance properties.

In the fixed magnetic disk drive, information read / write is performed on such a medium via a magnetic head. When the magnetic head is driven to perform read / write on the medium, the magnetic head is in a magnetically levitating traveling state due to the action of the airflow generated between the medium and the rotating medium. Slide. Therefore, when the coefficient of friction of the medium surface is large, there occurs a problem that a kind of burn-in state occurs between the magnetic head and the medium.

In order to eliminate such defects, the surface condition of the medium is
As far as possible, it is necessary for the surface roughness to have uniform fine projections without variation within the same medium surface and between media. In order to obtain a medium with such a uniform surface roughness, the substrate surface is precisely machined to the required uniform roughness by machining, then immersed and stored in static pure water, and taken out immediately before film formation A manufacturing method has been performed in which the substrate is precisely cleaned and a film is formed on the surface of the substrate which has been cleaned as much as possible.

[Problems to be solved by the invention]

However, in the above-mentioned conventional method, during the immersion storage of the substrate in still pure water before precision cleaning, particularly when the storage is performed for a long period (for example, 12 hours or more), the stainless steel for fixing and supporting the substrate is used. Residues such as polishing liquid and detergent adsorbed in trace amounts on jigs made of steel and other materials strongly adhere to the substrate surface via pure water and cannot be completely removed even after precision cleaning. This causes variations in the cleanliness of the substrate surface even when precision cleaning is performed under certain conditions. Also,
Such deposits induce oxidation of the substrate surface (oxidation of Ni) at the time of drying the substrate after precision cleaning and at the time of the subsequent sputtering. When a nonmagnetic metal underlayer, for example, a Cr underlayer is formed by sputtering on a substrate surface having a variation in surface state, uniform formation of surface microprojections due to crystal growth is hindered, and a magnetic layer and a protective layer are formed thereon. Even if the medium is manufactured by film deposition and lamination, there arises a problem that a constant surface roughness in which uniform fine projections are formed without variation within the same medium or between the media cannot be obtained, and the uniformity of the magnetic layer There is a problem that a high coercive force squareness ratio and a high squareness ratio cannot be obtained due to hindered crystal growth.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides a thin film magnetic recording medium having a high surface roughness and a high coercivity squareness ratio and a high squareness ratio having uniform surface minute projections within the same medium and between media. An object of the present invention is to provide a manufacturing method of the present invention.

[Means for Solving the Problems] According to the present invention, according to the present invention, a non-magnetic substrate surface is finely roughened and a non-magnetic metal base layer is formed on the non-magnetic substrate surface by sputtering. In a method of manufacturing a thin film magnetic recording medium in which a thin film magnetic layer and a protective layer are sequentially formed,
In a state where pure water is flowing violently against the substrate surface in pure water running water until the precision cleaning step before sputter film formation on the non-magnetic substrate after the fine surface roughening processing, and pure pure water is always in contact therewith. The problem is solved by a manufacturing method including a step of storing.

In order to realize a state in which pure water is flowing violently against the surface of the non-magnetic substrate stored in running pure water and clean pure water is always in contact with the surface, it is necessary to use pure water near the surface of the substrate while flowing pure water. It is preferable to perform bubbling with an active gas.
Further, pure water may be stirred near the substrate surface.

Nitrogen (N ₂ ) gas is preferably used as the inert gas for bubbling.

[Action]

As described above, the nonmagnetic substrate is immersed in pure water under flowing water, and the surface of the substrate is immersed and kept in contact with pure water, which is intensely flowing on the surface, so that the substrate surface can be stored during storage. It is possible to prevent contamination, and by performing precise cleaning under the required constant conditions immediately before film formation by sputtering, the substrate surface will be uniformly and extremely cleanly cleaned, and No local abnormal oxidation occurs. Therefore, when a nonmagnetic metal base layer is subsequently formed by sputtering on the substrate surface, fine surface projections due to crystal growth are formed uniformly, and the magnetic layer and
The medium obtained by forming the protective film has a constant surface roughness on which uniform surface minute projections are formed without variation within the same medium or between media.

Further, the crystal growth during the formation of the magnetic layer becomes uniform, a required constant crystal state can be obtained, and a medium having a high coercive force square ratio and a high square shape ratio can be obtained.

〔Example〕

FIG. 1 is a conceptual diagram of one embodiment of a pure water immersion storage device used in the manufacturing method of the present invention. FIG. 1 (a) is a cross-sectional view of a substrate to be stored viewed from a side. b) is the first
It is XX sectional drawing of figure (a). In FIG. 1, a substrate 1 to be immersed is held by a jig 2 made of stainless steel and immersed and stored in a storage tank 3. Pure water is supplied from pure water supply pipe 4 by arrows A,
It flows into the storage tank 3 as shown by the arrow B, and flows out from the overflow part 6 as shown by the arrow C. An arrow D from N ₂ gas supply pipe 5 is fed the N ₂ gas as indicated by the arrow E ejected in the pure water in the storage tank 3. A bubble state is generated by the N ₂ gas, and pure water in contact with the surface of the substrate 2 flows violently, so that a state where pure new pure water always contacts can be realized.

As described above, the substrate that has been immersed and stored for 12 hours while performing bubbling with N ₂ gas in a storage device in which pure water is overflowing is subjected to precision cleaning, and then a Cr underlayer, Co The medium of the example was manufactured by laminating an alloy magnetic layer and an aC protective layer.

For comparison, a medium of a comparative example was prepared in the same manner as in the example, except that a substrate stored for 12 hours by the conventional method of immersion in still pure water was used.

FIG. 2 shows the results of examining the surface roughness profiles of the media thus obtained. Second
FIG. 2A shows the profile of the medium of the embodiment, and FIG. 2B shows the profile of the medium of the comparative example. From FIG. 2, it can be seen that the surface microprojections are formed more uniformly on the medium surface of the example than in the comparative example.

For these media, the surface roughness parameter Δ
The results of measuring Cv (10% -1%) are shown in FIG. Third
From the figure, the average value of ΔCv (10% -1%) is 166 μm in the example.
m, the variation is as small as 28 μm, and the surface exhibits a uniform surface roughness with fine projections.
The average value of (10% -1%) is as small as 107 μm, and the variation is as large as 86 μm. Thus, it can be seen that uniform fine surface projections are not formed.

2 and 3, it is clear that the storage method of the embodiment is excellent.

Next, the magnetic properties of these media were measured.
Table 1 shows the results.

As can be seen from Table 1, the medium of the example has a higher squareness ratio S and coercive force squareness ratio S ^* than the medium of the comparative example, and it can be seen that the storage method of the example is excellent also in terms of magnetic properties.

〔The invention's effect〕

According to the present invention, in the method for manufacturing a thin-film magnetic recording medium, pure water flows violently against the surface of pure non-magnetic substrate having been subjected to surface microfabrication in running pure water until immediately before the precision cleaning step, so that pure non-magnetic substrate is always cleaned. Store immersed in water.

By manufacturing a medium using a non-magnetic substrate stored in such a manner, the surface roughness has uniform surface minute projections with small variations within the same medium and between media, and a high coercive force square. A medium having a high ratio and a high squareness ratio can be obtained.

In particular, the storage period of the substrate before precision cleaning is long (for example,
In the case of over 12 hours), it is possible to obtain a medium having the above-mentioned good surface roughness and excellent magnetic properties, and to obtain a great effect that the restrictions imposed by the storage period of the substrate are reduced in manufacturing the medium. Can be

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of one embodiment of a pure water immersion storage device used in the manufacturing method of the present invention, FIG. 2 is a diagram showing a profile of a surface roughness of a medium, and FIG. FIG. 2 (b) is a diagram relating to a medium of a comparative example,
FIG. 3 is a diagram showing the average value and variation of the surface roughness parameter ΔCv (10% -1%) of the media of the example and the comparative example, respectively. 1 ...... substrate, 2 ...... jig, 3 ...... storage tank, 4 ...... pure water supply pipe, 5 ...... N ₂ gas feed pipe, 6 ...... overflow part.

Claims (3)

(57) [Claims] 1. A non-magnetic substrate surface is subjected to a fine roughening process,
In a method of manufacturing a thin-film magnetic recording medium in which a non-magnetic metal base layer, a continuous thin-film magnetic layer, and a protective layer are sequentially formed on the non-magnetic substrate surface by a sputtering method, the non-magnetic substrate after the micro-roughening is sputtered. A thin film magnetic recording medium comprising a step of storing pure water in a state where pure water is flowing violently with respect to the substrate surface in pure water running water until a precise cleaning step before the film is kept in contact with pure water. Manufacturing method. 2. Bubbling with an inert gas in the vicinity of the substrate surface in order to vigorously flow the pure water on the surface of the non-magnetic substrate stored in the running pure water so as to always contact the pure water. 2. The method according to claim 1, wherein:
The manufacturing method of the thin film magnetic recording medium according to the above. 3. The method according to claim ₂ , wherein a nitrogen (N ₂ ) gas is used as an inert gas for bubbling.