JPS61115244A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having high corrosion resistance and large reproduced output by subjecting a Co-Cr alloy to vapor deposition under the conditions of specific gaseous oxygen pressure thereby providing a Co-Cr amorphous magnetic alloy film contg. oxygen atoms on a non-magnetic substrate. CONSTITUTION:The Co-Cr alloy is sputtered in a gaseous oxygen atmosphere under about 1X10<3>-3X10<3> Torr gaseous oxygen, by which the Co-Cr amorphous magnetic alloy film contg., for example, about 5-15atomic% oxygen atoms is obtd. Such thin metallic film type magnetic recording medium is highly resistant to corrosion, suitable for high-density recording and has substantial reproduced output. The thin metallic film type magnetic recording having the above- mentioned characteristics is obtd. at about 0.05-0.15mum/min, more preferably about 0.09-0.12mum/min sputtering rate.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method of manufacturing a magnetic recording medium suitable for horizontal magnetic recording, such as a magnetic disk in which recording and reproduction are performed using a floating ring head. be.

[Prior art and its problems]

In recent years, for high-density recording, for example, Co, Co-Ni,
A magnetic material such as Co-P or Co-N1-P is placed on a substrate,
For example, metal thin film type magnetic recording media formed by a physical vapor deposition (PVD) method such as sputtering, or a wet method such as electroplating or electroless plating have been proposed.

However, this type of magnetic recording medium has poor corrosion resistance,
There is a problem with using it under high humidity conditions, so it has been proposed to provide a rust prevention layer on the metal magnetic thin film layer, but if such a measure is taken, the manufacturing process will become complicated. This increases the cost, and increases the spacing of the magnetic head, resulting in a reduction in reproduction output, which is not necessarily desirable.

Therefore, as a magnetic material with better corrosion resistance, Co-C!
R-based magnetic alloys are attracting attention. Also, this co-Cr
System magnetic alloys are attracting attention because of their rich perpendicular magnetic anisotropy, which makes them suitable for perpendicular magnetic recording systems with fewer problems of self-demagnetization in short wavelength regions. That is, the Co-Cr-based magnetic alloy thin film magnetic recording medium can achieve higher density because it does not use a binder, and because it uses a perpendicular magnetic recording method, it can achieve higher density.
In addition, it has attracted attention due to its relatively excellent corrosion resistance, and for this reason, extensive research is being conducted intensively.

In order to increase the density, for example, in order to improve the perpendicular magnetic anisotropy, it is necessary to use an atmosphere of a gas containing oxygen atoms, for example, oxygen gas 5
Co-Cr based magnetic particles are deposited in an atmosphere of A magnetic recording medium comprising a perpendicular magnetization film has been proposed (Japanese Unexamined Patent Publication No. 17216/1983).

However, for example, in a recording/reproducing apparatus using a ring-type magnetic head, especially in a recording/reproducing apparatus using a floating ring head, when the magnetic recording medium proposed above is used, there is a major drawback such as a small reproduction output. C,
The magnetic recording medium proposed in JP-A-59-17216 is not necessarily superior.

[Disclosure of the invention]

The inventor of the present invention has discovered that a Co-Cr based magnetic alloy film has relatively excellent corrosion resistance and that it is a metal thin film type which is desirable in terms of high-density recording. As a result of repeated research on the manufacturing method of recording media, for example, Co
- When forming a Cr-based magnetic alloy film on a non-magnetic substrate, the PVD process is performed using oxygen gas of approximately 1×10 to 3×10
It has been found that the process can be carried out under an oxygen gas atmosphere under Torr conditions.

That is, oxygen gas approximately 1×10 to 3×10 TCrr
By sputtering a Co-Cr alloy in an oxygen gas atmosphere, a Co-Cr amorphous magnetic alloy film containing, for example, about 5 to 15 oxygen atoms is obtained. They discovered that it has excellent corrosion resistance, is suitable for high-density recording, and has sufficient reproduction output.

However, in order to obtain a metal thin film magnetic recording medium having the above characteristics, the sputtering rate may be about 0.05 to 0.15 μm/min, more preferably about 0.09 to 0.12 μm/min. found to be desirable.

Furthermore, oxygen gas pressure PO! (Torr)
,! The relationship between varnish batter rate SR, (μm7min) is
It was also found that this is the most desirable option in such cases.

〔Example〕

Using a Do magnetron sputtering device, a Co-Cr (Cr 20wt%) alloy was sputtered under the following sputtering conditions to form a Co-Cr based film with a thickness of 0.14 to 0.16 μm on the NiP-plated At substrate surface. An amorphous magnetic alloy film was formed to produce a metal thin film type magnetic recording medium.

Ar gas pressure Phr approx. 40 mTorr Ar gas flow rate FAr approx. 100 BOOMOl Gas pressure PO
: Approximately 4m Torr or less gas flow rate
Approximately 10,500M or less Sputter rate approximately 0.0
9~0.12μm/min Distance between target and At substrate
Approximately 100 mm A4 substrate temperature: approximately 150°C When the magnetic properties (coercive force Hc in the in-plane direction of the medium and square shape ratio S) of the metal thin film magnetic recording medium obtained as described above are measured using a sample vibrating magnetometer, , as shown in the drawing.

According to this, oxygen gas during sputtering is approximately 1×1
By setting the conditions to 0 to 3 X 10 Torr, a large coercive force in the in-plane direction of the medium and a large squareness ratio can be obtained, and a magnetic recording medium that can be custom-made for recording and reproduction using a ring-shaped magnetic head can be obtained. You can see that it is possible.

Furthermore, when examining the isolated reproduction waveform, it is a single peak reproduction waveform unique to the horizontally magnetized film, and the flying height is 0.25 μm.
The playback output using the ring type magnetic head is approximately 0.8m.
V or higher, and has a high reproduction output.

Further, when examining the composition of the magnetic layer of the above metal thin film magnetic recording medium, it is found that CO is about 71 to 78 atoms, and Cr is about 15 to 19 atoms.
It has about 5 to 15 atoms, and is amorphous rather than crystalline.

Next, in order to investigate the corrosion resistance of this metal thin film magnetic recording medium, it was left for 200 hours at a temperature of 60°C and a humidity of 90%, but almost no change was observed in the magnetic layer, indicating that the corrosion resistance was It was rich. In particular, 0. Gas pressure approx. 3 x 10 Torr or less (02 gas flow rate approx. 7.5
500M or less), a material with extremely high corrosion resistance is obtained.

〔effect〕

A magnetic recording medium with high corrosion resistance and high reproduction output can be obtained.

[Brief explanation of drawings]

The drawing is a graph of the magnetic customization of a magnetic recording medium obtained by practicing the present invention. Patent applicant: Victor Company of Japan Co., Ltd.

Claims (1)

[Claims] Oxygen gas is about 1×10^-^3~3 for Co-Cr alloy.
A method for manufacturing a magnetic recording medium, characterized in that a Co--Cr based amorphous magnetic alloy film containing oxygen atoms is provided on a non-magnetic substrate by vapor deposition under conditions of x10^-^3 Torr.