JPS62175926A - Vertical magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a vertical magnetic recording medium having good reproducibility and remarkably improved running durability by subjecting a magnetic layer to a plasma treatment then providing a protective layer thereon. CONSTITUTION:A vertically magnetized film having the axis of easy magnetization in the direction perpendicular to the film plane, for example, Co-Cr film is formed by a so-called thin film forming system such as sputtering, vacuum deposition or ion plating on one or both faces of a nonmagnetic substrate. The surface of the formed magnetic layer is subjected to the plasma treatment, then the protective layer is provided thereon. The plasma treatment includes a glow discharge treatment by DC, AC or high frequency or reverse sputtering treatment by high frequency or DC. Carbon, SiO2, Co-O-Cr, Cr-O, etc., are used as the protective layer and the film thickness is 0.002-0.1mum, more particularly preferably 0.005-0.05mum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a perpendicular magnetic recording medium and a method of manufacturing the same, and more particularly to a perpendicular magnetic recording medium with improved running durability and a method of manufacturing the same.

[Conventional technology]

In recent years, perpendicular magnetic recording materials have been proposed that use a magnetic recording medium having a magnetic easy axis in a direction perpendicular to the film surface of the recording medium. This perpendicular magnetic recording material f can be said to be a material essentially suitable for high-density recording, since the demagnetizing field in the recording medium decreases as the recording density increases, resulting in excellent reproduction output.

To perform magnetic recording using such a perpendicular magnetic recording material, a magnetic recording medium having a magnetic easy axis in a direction perpendicular to the film surface of the recording medium is required. As such a perpendicular magnetic recording medium, one in which a Co-Cr alloy or the like is formed by sputtering or the like on a substrate or support made of a non-magnetic material such as a polymeric material or a non-magnetic metal is known. .

Furthermore, in order to improve the recording and reproducing efficiency during perpendicular magnetic recording and reproducing, a high magnetic permeability layer comprising a soft magnetic material as an underlayer is provided under the perpendicular magnetic recording layer comprising the Co--Cr alloy film.
For example, a so-called double-layer perpendicular magnetic recording medium provided with a permalloy (Ni--Fe alloy) film is known.

Furthermore, in flexible disks and the like using the perpendicular magnetic recording material, so-called double-sided double-layer perpendicular magnetic recording media, in which the double-layer perpendicular magnetic recording medium is formed on both sides of a support, have a larger recording capacity. It is excellent because it improves curls and is easy to curl.

The side-type perpendicular magnetic media are also manufactured by applying the above materials to a support continuously or discontinuously using a sputtering device.

[Problem that the invention seeks to solve]

Such perpendicular magnetic media is expected to be used as a recording medium suitable for high recording densities, such as magnetic tapes and magnetic disks.
One major problem is that running durability is generally poor; for example, in the case of a perpendicular magnetic recording disk with a Co-Cr alloy film, the alloy layer on the surface will condense after about 10,000 running passes. It is often impossible.

In order to solve such problems, carmen, SiO2
, BN (Japanese Unexamined Patent Publication No. 58-133627), StC (
It has been proposed to provide a protective layer such as JP-A No. 58-130437 on the surface of the magnetic layer by grating or the like.

However, even with these treatments, the improvement in running durability is still insufficient (1), and in particular, the reproducibility of the products is poor even in the same manufacturing process, and products with good durability and products with extremely poor durability can be obtained. There was a problem in that it was not possible to obtain a product with consistently good durability.

Therefore, an object of the present invention is to provide a perpendicular magnetic recording medium with good reproducibility and significantly improved running durability, and a method for manufacturing the same.

[Means for solving problems]

The present invention was developed as a result of extensive research to solve the above problems.
The inventors have discovered that by providing a protective layer after plasma-treating the magnetic layer, a perpendicular magnetic recording medium with significantly improved durability can be obtained with good reproducibility, and the present invention has been achieved.

That is, the present invention provides a perpendicular magnetic recording medium in which a magnetic layer having perpendicular anisotropy and a protective layer are provided on at least one surface of a nonmagnetic substrate, characterized in that the surface of the magnetic layer is plasma-treated. A method for manufacturing a perpendicular magnetic recording material by providing a magnetic layer having perpendicular magnetic anisotropy and a protective layer on at least one surface of a perpendicular magnetic recording medium and a non-magnetic substrate by sputtering, in which a magnetic layer is provided. There is a method for manufacturing a perpendicular magnetic recording medium, which is characterized in that the perpendicular magnetic recording medium is then subjected to plasma treatment and then a protective layer is provided.

The present invention will be explained in detail below.

In the present invention, first, a perpendicular magnetic film having a magnetic easy axis in a direction perpendicular to the film surface on one or both sides of a non-magnetic substrate, such as a Co-Cr film, is deposited on a so-called thin film by snootering, vacuum evaporation, ion blating, etc. Forming material is formed. In this case, before forming the perpendicular magnetic film, a soft magnetic film with low coercive force or high magnetic permeability, such as an A-Malloy film, may be similarly provided by snogging or the like. Further, the above-mentioned perpendicular magnetic film etc. may be a single layer or may be composed of a plurality of layers.

Further, a nonmagnetic underlayer may be provided between the substrate and the perpendicular magnetic layer, or a nonmagnetic intermediate layer may be provided between the soft magnetic layer and the perpendicular magnetic layer. Therefore, the magnetic layer of the present invention includes only a perpendicular magnetic film as described above, and a case where a soft magnetic film and a perpendicular magnetic film are provided. ) has a particularly remarkable effect on film-like polymer materials such as polyimide and polyamide, but it is also applicable to metal materials, non-metal materials such as glass, etc.

As the material for the soft magnetic film, Ni-Fe, Ni-F
Not limited to permalloy alloys such as e-Mo, Ni-Fe-Mo-Cu, but also Fe, Fe-AI-S
i, F@-Ni-0, Fe-TI, Ni-F
e-Cu-Cr-Mn, Fs-81-B.

Fe-B-C, Fe-Al, Co-V-FeXCo
-Ta.

Co-Zr, Co-Nb-Zr, Co-T
iXCo-Nb-Ta, Co-Nt-Zr,
Fo-Ni-P, Fe-Co-Zr, Co
So-called soft magnetic alloy materials such as -Mo-Zr can also be applied.

The film thickness is preferably about 0.03 to 5 microns, particularly about 0.1 to 1 micron.

For the perpendicular magnetic film, it is necessary that the magnetic easy axis is oriented in a direction substantially perpendicular to the support surface, and C is known as a material for the perpendicular magnetic film.

An alloy material containing Cr and Cr as main components is desirable.

The film thickness is selected to be about 0.03 to 5 microns, and preferably about 0.05 to 1 micron.

As the film forming means, vapor deposition, sputtering, etc. can be used, but a so-called continuous sputtering method having a plurality of high-speed sputtering sources disposed around a plurality of cylindrical cans is preferable, as described in Examples below.

In the sputtering chamber, for example, in the case of a Co--Cr alloy, a Co--Cr alloy may be used as a target, or Co and Cr may be used as separate targets.

The temperature of the cylindrical can is preferably 30° C. or higher when forming a hard magnetic film such as a Nogmalloy film to prevent magnetic anisotropy from occurring in the plane of the hard magnetic film.

On the other hand, if the can temperature is made too high, gas may be released from the support and the temperature may deteriorate. The temperature is preferably 90° C. or lower since precipitation of mer and the like may occur.

In order to particularly reduce magnetic anisotropy and film surface irregularities,
A temperature of 45 to 65°C is particularly desirable. On the other hand, c.

When forming a -Cr film, it is desirable to heat the cylindrical can to a temperature of 90°C or higher in order to obtain the desired He (perpendicular) magnetic film; The above is particularly desirable.

The present invention is characterized in that the surface of the magnetic layer formed as described above is subjected to plasma treatment, and then a protective layer is provided. Among these, carzene is particularly preferred.

The plasma treatment includes glow discharge treatment using direct current, alternating current, or high frequency, or reverse sputtering treatment using high frequency or direct current.

Glow discharge treatment is performed by subjecting a magnetic recording medium provided with a magnetic layer to 't'lo-' to 10T in a vacuum chamber (for example, a sputtering device).
A voltage of about 500 V is applied in an argon atmosphere of 500 V to generate a glow discharge on the surface of the magnetic layer.

In the reverse sputtering process, when the magnetic layer is provided by sputtering (cylindrical can -, target - +),
This voltage is applied in the opposite direction (+ to the cylindrical can, - to the target), and a voltage of about 50V is applied to strike the surface of the argon ion magnetic layer.

A protective layer is then provided on the surface of the magnetic layer subjected to the plasma treatment in this manner by sputtering or the like.

As the intermediate layer, carzen, sto2, Co-0-C
r, Cr-0, etc. are used.

The thickness of the protective layer is preferably 0.002 μm to 0.1 μm, particularly 0.005 to 0.05 μm.

According to the present invention, a perpendicular magnetic recording medium with significantly improved running durability can be obtained with good reproducibility.

〔Example〕

FIG. 1 is a schematic diagram showing an example of a sputtering apparatus used for producing the perpendicular magnetic recording medium of the present invention.

A double-sided double-layer perpendicular magnetic medium was fabricated using a double-sided continuous star/q-tutter device shown in FIG. A roll-shaped polyimide film 41 with a thickness of 50 microns is set on the delivery shaft 42, and an intermediate roller and cooled cylindrical cans 43, 4
4 and then wound onto a winding shaft 45. The vacuum chamber is roughly divided into three parts: a delivery chamber 46, a sputtering chamber 47, and a winding chamber 48. Each chamber is partitioned by a partition wall 49.50, and each chamber is evacuated by exhaust systems 51.52 and 53.54, respectively. did.

The sputter chamber includes sputter cathodes 55, 57 and C of DC planar magnetron material having two carbons.
Snogger cathodes 56, 58 of RF planar magnetron material with o-Cr targets (18 wt% Co82-Cr) were provided.

The sputtering chamber 47 of such a sputtering device is
After evacuation to a pressure of 10 torr or less, pAr gas was introduced through the gas introduction system 59, and the pressure was approximately 5 x 10-'
maintained at torr. Delivery shaft 42 p 20 tm/
On the polyimide film 41 fed out at a conveying speed of 1 m, first, at the position of the can 43, Co-Cr of about 3,000× is applied to one side (0 side) by a sputter cathode 56.
A film was formed. Next, at the position of the can 44, the spanter cathode 58 is applied to the other surface (worked surface) by approximately 3.000 mm.
A Co-Cr film of X was formed and wound around a winding shaft 45.

Did you form a Co-Cr film on both sides in this way? The Liimide film is reversed again and conveyed from the take-up shaft 45, the polarity of the vines is switched, and reverse vine vines are carried out in an Ar atmosphere at the positions of the cans 43 and 44, and both surfaces are plasma treated. After that, it was wound up on a winding shaft 42.

Next, the polarity of the snow vine is restored to its original polarity, and it retracts from the winding shaft 42, forming a protective layer of carmen can-rss, s'y at positions 43 and 44, and winding it around the winding shaft 45. I took it.

The perpendicular magnetic media thus prepared were cut into 3.5 inch diameter disks and assembled into commercially available disk jackets.

After recording on a commercially available 3.5 floppy disk drive, 600r, p, m, ? The vehicle was rotated and run while monitoring the reproduction signal, and the number of A passes until the vehicle stopped running was measured. (The test was stopped after a maximum of 10 million passes.) For comparison, we created a sample without the above Creation 1 plasma treatment (reverse suction treatment) and a sample with only a Co-Cr layer, and conducted a similar test. went.

Ten samples of each were made and tested.

The results obtained are shown in Figure 2.

〔Effect of the invention〕

As is clear from the results shown in Figure 2, the sample with only a Co-Cr film became unable to run at approximately 10 tOOO/e.
In the case where the carmen protective layer was provided without plasma treatment, the running durability varied from 10,000 to 10,000,000 times, and the reproducibility was poor. On the other hand, in the case of the present invention, it was possible to produce perpendicular magnetic media with excellent durability and good reproducibility, with a traveling pass of approximately 10 million passes.

Although the above embodiment shows the case where the plasma treatment is performed by reverse sputtering, it is also possible to perform the plasma treatment by glow treatment.

Further, instead of only having a Co--Cr film, a Co--Cr film may be provided on top of a soft magnetic layer as described above.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an apparatus for manufacturing a perpendicular magnetic medium according to the present invention, and FIG. 2 is a diagram showing the results of a running/suspension test in the example. 43.44...Can, 55,57...Carmen cand, 56,58...Co-Cr cathode. Figure 1 Figure 2 Procedural amendment document February 72, 1988

Claims (3)

[Claims] (1) A perpendicular magnetic recording medium comprising a magnetic layer having perpendicular anisotropy and a protective layer on at least one surface of a non-magnetic substrate, wherein the surface of the magnetic layer is plasma-treated. recoding media. (2) A method for manufacturing a perpendicular magnetic recording material by providing a magnetic layer having perpendicular magnetic anisotropy and a protective layer on at least one surface of a nonmagnetic substrate by sputtering, in which the magnetic layer is provided and then plasma treated. . A method for manufacturing a perpendicular magnetic recording medium, the method comprising: then providing a protective layer. (3) The method for manufacturing a perpendicular magnetic recording medium according to claim (2), wherein the formation of the magnetic layer, the plasma treatment, and the formation of the protective layer are performed in the same vacuum chamber.