JPS61253636A - Production of vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability and productivity of the titled vertical magnetic recording medium by providing cobalt oxide on the vertical magnetic recording layer with an opposed target system sputtering method in an oxidizing gas atmosphere. CONSTITUTION:A high-permeability metallic thin layer 2 consisting of an nickel- iron alloy and a vertical magnetic recording layer 3 consisting of a cobalt- chromium alloy thin film are successively laminated on both surfaces of a substrate 1 of a polyethylene terephthalate film by using an opposed target system sputtering device to obtain a both-faces 2 layered medium. Both targets are composed of metallic cobalt, an oxidizing gaseous mixture of argon and oxygen contg. 10-50vol% oxygen is introduced into a vacuum vessel from a gas introducing system and the gas pressure during sputtering is kept at 0.5-2.5pa. Electric power enough to obtain the desired sputtering speed and film characteristic is impressed on the targets to form a protective layer 4 on the both-faces 2-layered medium and a vertical magnetic recording medium having a metallic luster is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application] The present invention relates to a method for manufacturing a perpendicular magnetic recording medium, and more particularly to a method for manufacturing a thin film type perpendicular magnetic recording medium with excellent wear resistance.

[Prior art]

In recent years, the demand for high-density recording has become higher and higher, and the use of ferromagnetic metal layers as magnetic recording layers, and
A device using a cobalt-based alloy layer having perpendicular magnetic anisotropy has been proposed, such as in Japanese Patent No.-91. However, in the case of a thin-film magnetic recording medium using such a metal thin film as a magnetic recording layer, there is a drawback that it is susceptible to wear and damage and lacks durability because of the large frictional resistance with the magnetic recording head.

For this reason, various proposals have been made in the past in which organic polymers, high-hardness metals, ceramics, etc. are further provided as protective layers on ferromagnetic metal thin films.

However, the abrasion resistance of the thin film type magnetic recording medium, that is, the life span of the magnetic recording medium when the magnetic recording medium is repeatedly run by a magnetic recording head, is inferior to that of the conventional coating plate magnetic recording medium. It is still not in a sufficient state for practical use.

[Purpose of the invention]

The present invention was made in view of the current situation.

The object of the present invention is to provide a method for manufacturing a perpendicular magnetic recording medium that can stably form a thin film type perpendicular magnetic recording medium with excellent wear resistance.

[Structure and operation of the invention]

That is, the present invention applies facing-target sputtering in an oxidizing gas atmosphere using cobalt metal as a target on a perpendicular magnetic recording layer when manufacturing a thin-film perpendicular magnetic recording medium whose perpendicular magnetic anisotropy is made of a metal thin film. 1. A method of manufacturing a perpendicular magnetic recording medium, characterized in that a cobalt oxide protective layer is provided by a method.

Here, the facing target sputtering method is referred to as JP-A-57-
As is known from Japanese Patent Application Laid-open No. 158380 and Japanese Patent Application Laid-open No. 193528/1984, a substrate is placed on the sides of a pair of targets facing each other with a predetermined distance apart in a vacuum chamber, and a positive angle is set between the targets in the vertical direction. This is a sputtering method in which a magnetic field for trapping particles is formed and sputtering is performed to form a film on a substrate.

1. In this known facing target sputtering method, the present invention targets cobalt metal and forms a film while oxidizing the sputtered cobalt metal in an oxidizing gas atmosphere. A film is formed to serve as a protective layer.

By the way, the cobalt oxide obtained in the present invention was confirmed by Auger electron spectroscopy (AES) K to be a cobalt oxide containing C08o4 as a main component. In addition, when analyzed by the AES method, a slight variation in stoichiometry was observed in the film thickness direction, and therefore it is estimated that the main component is CO5O.

Therefore, an oxidizing gas atmosphere is a gas atmosphere containing oxygen and/or ozone necessary to oxidize cobalt to form a cobalt oxide film. This is achieved by introducing a mixed gas of active gas and oxygen or ozone. It should be noted that the intended cobalt oxide film could be stably formed by introducing a mixed gas of oxygen or ozone with a concentration of lo to 50 vo 1%.

The perpendicular magnetic recording medium to which the above-mentioned present invention is applied is not limited to the perpendicular magnetic recording medium as long as its magnetic recording layer is made of a thin metal film, and all those known in the above-mentioned Japanese Patent Publication No. 58-91 etc. are applicable. can.

Specifically, a thin film of metal such as a cobalt alloy having perpendicular magnetic anisotropy is formed on a substrate.

There are those in which the above-mentioned perpendicular magnetic anisotropy metal thin film is laminated on a high magnetic permeability metal thin film such as iron, permalloy, cobalt-niotiosilcon alloy, or the like. Further, as the substrate, a polymer film such as polyester, a glass plate, an aluminum alloy plate, etc. are used depending on the purpose, such as magnetic tape, floppy disk, magnetic disk, etc. The method for forming the above-mentioned metal thin film on the substrate includes sputtering, vacuum evaporation,
Known methods such as ion blating method and electroplating method can be applied. Among these, the method of forming the above metal thin film on a polymer film as a substrate using the facing target sputtering method enables equipment integration and continuous film formation when combined with the method of the present invention, and improves productivity. It is advantageous in that a good manufacturing method can be realized.

The present invention as described above, that is, by providing cobalt oxide on the perpendicular magnetic recording layer using the facing target sputtering method in an oxidizing gas atmosphere, it has been possible to greatly improve the durability of the perpendicular magnetic recording medium, and also improve the productivity of the perpendicular magnetic recording medium. A method for manufacturing a perpendicular magnetic recording medium with a protective layer with good properties has been realized.

Embodiments of the present invention are shown below.

[Implementation row]

FIG. 1 shows the structure of a perpendicular magnetic recording medium to be used in the practical example, which is a flexible double-sided perpendicular magnetic recording medium for a floppy disk, and was manufactured as follows.

A polyethylene terephthalate film with a thickness of 50 μm was used as the substrate 1, and a nickel iron film of 0.4 μm was coated on both sides in the same manner as in Example 1 using the facing target sputtering apparatus disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 59-193528. A thin metal layer 2 with high magnetic permeability made of an alloy and a perpendicular magnetic recording layer 3 made of a 0.4 μm thin film of a chromium (chromium:2 (hvt%)) alloy are laminated in sequence. A layered medium was obtained.

Next, a protective layer 4 was formed on the double-sided double-layered medium obtained in the following manner to produce the intended perpendicular magnetic recording medium. That is, in the above-mentioned facing target type sputtering apparatus, both targets are made of cobalt metal, and a mixed gas of argon and oxygen having an oxygen concentration of 10 to 50 vol. 1% as an oxidizing gas is introduced into the vacuum chamber as a sputtering gas from the gas introduction system. while increasing the gas pressure during sputtering to 0.5
A protective layer 4 with a thickness of 30 OA was formed on the double-sided dual-layer medium by maintaining the temperature at ~2.5 pa and applying power to the target to obtain the desired sputtering speed and film properties. A perpendicular magnetic recording medium with bluish metallic luster was obtained (practical row).

The obtained protective layer 4 is estimated from Auger electron spectroscopy (AES) to be a cobalt oxide layer containing Co304 as a main component.
R method (ATR method using Fourier transform infrared spectrophotometer (FT-IR) J IR-40X K manufactured by JEOL Ltd.)
When the background of the base magnetic layer was removed by the difference spectrum method and the surface analysis was performed using f IRE TOL and TE KR8-5, there was an intensity drop near 6800II-' in the range from 800C1ll-' to 4QQcm-'. It was analyzed to be a cobalt oxide layer exhibiting a spectral distribution with the highest absorption peak and the second highest absorption peak near 610°C.

Circles and plates with a diameter of 5.25 inches were punched out from the perpendicular magnetic recording media of the above examples, and evaluated using a commercially available floppy disk drive device. The results are shown in the table.

On the front, the sliding part (part of the head slider) is made of glass (BK).
7) (practical row 1), barium titanate (practical row 2),
3 using an evaluation device using a dummy head using alumina titanium carbide (A/TiC) (actual row 3).
The following shows the results of evaluating the surface roughness of the sample after rotating it for 3 million passes at 0.00 rpm.

In other words, durability evaluation was performed by measuring the surface roughness of the suction/glue before and after the sliding test using a surface roughness meter (5URF COM).

The center line average roughness CLA was determined using the CLA (manufactured by Tokyo Seimitsu ■), and the relative surface roughness was calculated by dividing the CLA value after sliding by the CLA value before sliding.

For comparison, the results of evaluations of perpendicular magnetic recording media having the same configuration as in the above-mentioned example except that no protective layer is provided are shown in comparison columns 1, 2. Shown as 3.

As is clear from the table, in the examples using the protective layer made of cobalt oxide of the present invention, the surface roughness of the medium did not change much before and after the sliding test.

The results were better than any of the comparison rows, demonstrating high durability.

Furthermore, it has become clear that Alumina Titanium Carbide (AI!Tic) is the best material for a part of the head slider to be combined with the vertical alignment medium obtained in the present invention.

In view of its gist, the present invention is not limited in any way to the Flopanobee disk shown in the embodiment as described above, but can be applied to so-called hard disks, magnetic tapes, etc., such as aluminum disks treated with alumina oxidation. Needless to say, it can be applied. In addition, other known film forming methods other than those described above can be applied to the method for producing the coating layer.

[Brief explanation of drawings]

FIG. 1 is a partial side sectional view showing the configuration of an embodiment of the present invention. 1: Substrate, 2: High magnetic permeability metal thin film layer. 3: Cobalt-chromium alloy thin film layer. 4: Cobalt oxide protective layer

Claims (1)

[Claims] 1. When manufacturing a thin-film perpendicular magnetic recording medium in which the perpendicular magnetic recording layer is made of a metal thin film, cobalt oxidation is performed on the perpendicular magnetic recording layer using a facing target sputtering method in an oxidizing gas atmosphere using cobalt metal as a target. A method for manufacturing a perpendicular magnetic recording medium, characterized by providing a material protection layer.