JPS6260126A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease spacing and to obtain a magnetic recording medium having surfaces with which adsorption hardly arises by etching magnetic layers which are formed on substrate surfaces and contain Cr in a radical chlorine atmosphere, thereby forming recesses at the grain boundaries. CONSTITUTION:The magnetic layers 2, 3 consisting of, for example, Co-Cr, etc. contg. Cr are formed on both faces of the substrate 1 consisting of a polyimide film, etc. The substrate 1 is subjected to high-frequency etching in gas such as CCl4, CFCl2 or CF3Cl to form the recesses 8 at the grain boundaries 6 of the magnetic layers 2, 3 by selective etching of Cr. Protective film 4, 5 consisting of Si3N4, etc. are formed on the magnetic layers 2, 3. The fine ruggedness is thus formed on the surfaces of the magnetic layers 2, 3, by which the spacing is made smaller and the generation of the adsorption is made hard.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a method of manufacturing a magnetic recording medium.

[Technical background of the invention and its problems]

In general, one purpose of all recording media, not just magnetic recording media, is high density recording.

In the field of magnetic recording, high density is being achieved by vapor deposition and the like in perpendicular magnetization recording as well as in-plane recording. One factor for achieving high density in a magnetic recording medium is the spacing between the medium and the magnetic head, and it is preferable to reduce the spacing between the medium and the magnetic head. Vapor deposition or sputtering is an effective means for reducing surface irregularities of the magnetic layer and increasing the spacing between the magnetic layer and the magnetic head.

On the other hand, as the spacing is made smaller, the surface of the magnetic layer becomes smoother and a phenomenon occurs in which the magnetic head is attracted and becomes immobile. In order to achieve high density, it is necessary to solve the contradictory problems of reducing spacing and preventing adsorption.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing a magnetic recording medium that has a surface that reduces spacing and is less susceptible to adsorption.

[Summary of the invention]

In this invention, after forming a magnetic layer, this magnetic layer is etched in an atmosphere containing radical chlorine. If Cr is contained in the magnetic layer, the Cr portion is selectively etched, and the magnetic layer is etched. This is a method of manufacturing a magnetic recording medium in which recesses are formed in grain boundary portions of layers.

Generally, in order to give the surface of a magnetic material a shape that does not cause attraction, methods are known in which worm-like protrusions are created or the height and density of the protrusions are determined.

However, from the standpoint of spacing, it is preferable to form a surface where adsorption does not occur by partially etching, for example, grain boundary areas, instead of creating protrusions to avoid adsorption. Furthermore, in order to make the protrusions having the above-mentioned shape, it is common to make the protrusions on the surface of a film serving as a base, and then form a magnetic layer thereon. However, this method has the drawback that the orientation is poor in a 4fK perpendicular magnetic layer.

Therefore, an example of a magnetic recording medium obtained by the manufacturing method of the present invention is constructed as shown in FIG.
A magnetic layer 2.3 made of Cr is formed, and a protective layer 4.5 made of 513N4 is further formed on each of the magnetic layers 2,3.

A lubricating layer (not shown) is formed on the protective layers 4 and 5 as necessary.

Next, a method of manufacturing this magnetic recording medium will be explained.

First, magnetic layers 2 and 3 made of, for example, Co--Cr are coated on both sides of a substrate 1, such as a polyimide film, with a thickness of 50 to 70 μm, respectively, to a thickness of 0.1 to 0.811 m.

Formed by sputtering method.

Next, the substrate 1 on which the magnetic layers 2 and 3 have been formed is placed in a vacuum chamber, and after once exhausting the air, a gas containing chlorine, such as CCl4. , CFCl2. CF3Cl
etc., and while cooling the substrate 1, the substrate holder on the substrate 1 side is set as a negative electrode, the mesh electrode facing the substrate holder is set at ground potential, and high frequency power is applied. The input power is 5 to SOW, and etching is completed in 5 to 20 minutes.

Next, after exhausting the introduced gas, Arf! Etching is performed for about 2 minutes with an input power of 5 to 50 W to remove the adsorbed gas and the damaged area. During this etching process, if necessary (to increase the etching speed), 10 to 5 0□
may be mixed. As a result, the surface of the magnetic layer has a 100%
A ~300X deep recess is formed along the grain boundaries.

Next, the substrate 1 is transferred to another vacuum chamber, and protective layers 4 and 5 made of, for example, Sl and N4 and having a thickness of about 200 mm are formed on the magnetic layers 2 and 3, respectively. Then, if necessary, a protective layer 4,
A lubricating layer (not shown) is formed on the 5.

In addition, in the above etching process, O is added to the above composition gas.
Since r has a higher etching speed than Co, the appearance is upper C.
Selective etching of r is performed.

In particular, grain boundary areas have a higher etching rate than other areas, so they become concave. Further, the etching rate of the abnormal protrusions is also high, and as a result, the surfaces of each magnetic layer 2.3 are flattened except for the grain boundary portions. As already mentioned, a surface having such a structure is preferable for the surface of a magnetic recording medium.

Note that even if a protective layer is formed on such a surface magnetic layer,
The thickness of the protective layer is thin, and the surface of the protective layer has a shape that faithfully reflects the shape of the surface of the magnetic layer.

[Embodiments of the invention]

First, magnetic layers 2 and 3 each made of Co-Cr were formed to a thickness of 0.2 μm on both sides of a base 10 made of a polyimide film with a thickness of 60 μm by sputtering.

Next, the substrate 1 on which the magnetic layer 2.3 has been formed is placed in a vacuum chamber, and after being evacuated once, the CF2Cl□ gas is
rr was introduced, and while the substrate 1 was being cooled, the substrate holder on the substrate 1 side was set as a negative electrode, the mesh electrode facing the substrate holder was set at ground potential, and high frequency power was applied. The input power was 20 W, and etching was performed for 5 minutes.

Next, after exhausting the introduced gas, Ar gas was introduced, and etching was performed for 2 minutes with an input power of 20 W to remove the adsorbed gas and the damaged portion.

Next, the substrate 1 was turned over, and the magnetic layer on the other side was etched in the same manner as described above.

Next, the substrate 1 is transferred to another vacuum device, and protective layers 4 and 5 made of 815N4 are placed on each of the magnetic layers 2 and 3 to a thickness of 200X.
was formed.

〔Effect of the invention〕

According to this invention, the following excellent effects can be obtained.

That is, in general, when the magnetic layers 2 and 3 are Snokkuta films of Co--Cr, the grain boundaries 6 on the surface are extremely difficult to discern, as shown in FIG. 2, and only grains 7 indicating the existence of grain boundaries can be seen here and there. . By etching the magnetic layers 2 and 3 having such surfaces in the above-mentioned atmosphere as in the present invention, the etching rate of the grain boundary 6 portion is higher than that of other portions, so that the etching rate shown in FIG. As shown in FIG. 2, recesses 8 are formed along the grain boundaries 6, and as a result, fine irregularities are formed on the surfaces of the magnetic layers 2 and 3. This unevenness is not deep and minute. Therefore, it is possible to reduce the spacing and provide a surface shape free from adsorption. Figures 2 and 3
In the figure, only the magnetic layer 2 is illustrated, but the same applies to the magnetic layer 3.

In other etching methods other than the present invention, such as solution etching, small pinholes etc. are corroded and the magnetic layers 2 and 3 are etched.
Another drawback is that the substrate tends to peel off easily, and in reverse slat etching, the temperature of the entire substrate 1 tends to rise, making the medium susceptible to thermal damage.

In the above embodiments, a polyimide film is used as the substrate 1, but the substrate 1 may be a polyimide film, a polyester film, an aluminum substrate, or the like.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a magnetic recording medium obtained according to the present invention, and FIGS. 2 and 3 are sectional views showing essential parts of the magnetic recording medium used for explaining the invention in detail. The images are before and after etching, respectively. DESCRIPTION OF SYMBOLS 1...Substrate, 2, 3... Magnetic layer, 4, 5... Protective layer, 6... Grain boundary, 8... Recessed part. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure A 2 Figure 3

Claims (2)

[Claims] (1) In a method for manufacturing a magnetic recording medium in which a magnetic layer is formed on the surface of a substrate and a protective layer is further formed on the magnetic layer, after forming the magnetic layer, the magnetic layer is heated in a radical chlorine atmosphere. A method of manufacturing a magnetic recording medium, comprising forming recesses at grain boundaries of the magnetic layer by etching. (2) The method for manufacturing a magnetic recording medium according to claim 1, wherein the magnetic layer contains Cr.