JPH0696431A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To control grain diameter and to obtain high coercive force by interposing a metal film based on at least one of Cu, Rh, Pd, Ag, Ir, Pt and Au between a nonmagnetic substrate and an underlayer of Cr, etc. CONSTITUTION:A metal film 12 based on Cu, Rh, Pd, Ag, Ir, Pt or Au is interposed between a glass substrate 11 and a Cr underlayer 13. A magnetic layer 14 of a Co-based alloy such as CoCrTa and a protective film 15 of SiO2, etc., are formed on the Cr underlayer 13 to produce a thin film magnetic disk. The metal film 12 prevents oxygen, etc., from the substrate 11 from reaching the Cr underlayer 13 and brings such crystal orientation that the (110) face of Cr is made liable to epitaxialgrow in a direction parallel to the surface of the substrate. The (110) face can be made parallel to the surface of the substrate and crystal growth fit to attain high coercive force can be carried out.

Description

Detailed Description of the Invention

[0001]

The present invention relates to glass, ceramics,
The present invention relates to a magnetic recording medium in which a magnetic film or the like is formed on a non-magnetic substrate such as carbon.

[0002]

2. Description of the Related Art In a magnetic disk drive for computers,
In recent years, there has been a strong demand for higher capacity, but in order to increase the capacity, it is necessary to increase the recording density of the magnetic recording medium. In order to increase the recording density, a substrate having a smooth surface and a high coercive force of the magnetic recording medium are required to enable the magnetic head to have a low flying height. Conventionally, an aluminum substrate has been used as a substrate for a magnetic recording medium, but it has been considered to use a non-magnetic substrate such as glass, ceramic, or carbon as a substrate having more excellent smoothness. When an aluminum substrate is used, it is usually several tens.
A NiP plating layer having a thickness of μm is provided, and a Cr underlayer film, a magnetic film, and a protective film are laminated on the NiP plating layer. But glass and ceramic,
In the case of a carbon substrate or the like, if a Cr underlayer or magnetic film is directly formed on it, a high coercive force cannot be obtained in many cases. Although the reason for this has not been clarified yet, the crystal growth of the underlying Cr film is different from the case of forming the film on NiP on the aluminum substrate due to the influence of gases such as oxygen and water generated from the substrate. It is considered that this also affects the crystal growth of the magnetic film to be formed thereon and causes undesirable crystal growth in order to obtain a high coercive force. In order to solve these problems, a non-magnetic film of a metal such as Ti, Mo, Zr, Al, Mn, W or Si, or an oxide or nitride such as SiO ₂ , Al ₂ O ₃ , TiN or AlN is formed on the substrate. There has been proposed a magnetic recording medium in which a film (hereinafter, this film is referred to as an intermediate film) is formed, and a Cr underlayer film, a magnetic film, and a protective film are laminated in that order to improve the coercive force slightly. (JP-A-2-29923)

[0003]

As described in the above-mentioned prior art, in order to obtain a high coercive force in a magnetic recording medium using a non-magnetic substrate such as glass, Ti, Mo to promote crystal growth of Cr desirable. , Zr, Al, Mn, W,
Metals such as Si, Nb, Ta, Y, Hf, rare earth elements, and S
The coercive force can be increased up to about 1000 Oe by forming a non-magnetic intermediate film of oxide or nitride such as iO ₂ , Al ₂ O ₃ , TiN and AlN. However, a coercive force of 1400 Oe or more is required to cope with the recent increase in recording density. The coercive force of the magnetic recording medium is related to the crystal orientation, crystal grain size, or microstructure of the magnetic film, but the crystal grain size and crystal orientation of the magnetic film depend on the crystal orientation and crystal grain size of the underlying Cr film. Similarly, it is considered that the Cr film is greatly affected by the crystal grain size and crystal orientation of the underlying intermediate film. Therefore, the crystal grain size and crystal orientation of the intermediate film, which is the base of the Cr film, have a great influence on the coercive force, and it is necessary to select an appropriate material. The object of the present invention is to control the crystal orientation and the crystal grain size of the Cr underlayer and the subsequent magnetic layer by selecting an appropriate material capable of obtaining a higher coercive force than that of the conventionally known intermediate film, and to control the crystal grain size of 1400 Oe or more. To obtain a high coercive force.

[0004]

In order to achieve the above object, the present invention is a magnetic recording medium comprising a non-magnetic substrate such as glass, ceramics, carbon or the like, on which a base film such as Cr, a magnetic film and a protective film are laminated. In the above, a metal film containing at least one of Cu, Rh, Pd, Ag, Ir, Pt and Au as a main component was provided between the non-magnetic substrate and the underlying film such as Cr. These metals play a role in preventing oxygen and the like from the substrate from reaching the underlying Cr film, and at the same time, the Cr (110)
The crystal orientation is such that the surface easily grows epitaxially in the direction parallel to the substrate surface. That is, all of these metals have an fcc structure, and when deposited on an amorphous material such as a glass substrate, the (111) plane of the fcc metal grows parallel to the substrate. The (110) plane of Cr having the bcc structure is epitaxially grown on this fcc (111) plane. It is considered that this is because the atomic number densities of the bcc (110) plane and the fcc (111) plane are close to the atomic arrangement. In this way, the strong orientation of the (110) plane of Cr causes the C of Co to grow.
The axis is oriented more parallel to the film surface, and the coercive force can be increased.

[0005]

[Function] Cu, Rh, Pd, Ag provided on the substrate,
The intermediate film of Ir, Pt, and Au has a function of preventing a gas such as oxygen generated from the substrate from diffusing into Cr as the base,
In addition, the orientation of the (110) plane of Cr is strengthened, and as a result, the C axis of the magnetic film can be made more parallel to that in the case where no intermediate film is used on the substrate surface, and crystal growth desirable for obtaining high coercive force can be achieved. It is thought that it can be realized.

[0006]

EXAMPLES The present invention will be described in detail below based on examples. (Embodiment 1) FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention. In the figure, 11 is a glass substrate made of chemically strengthened glass, crystallized glass, ceramics or the like, and 12 is Cu, R provided on both sides of the substrate.
A metal film containing one of h, Pd, Ag, Ir, Pt, and Au as a main component, 13 is a Cr underlayer, and 14 is CoCrT.
a, a Co-based alloy magnetic layer such as CoNiCr or CoCrPt, 15 a protective film made of C, SiO ₂ , ZrO ₂ or the like, 1
6 is a lubricant. The feature is that the metal film 1 having the fcc structure is provided between the underlying Cr film and the glass or ceramic substrate.
2 is provided to prevent oxygen and the like from diffusing and prevent normal crystal growth of the Cr film from being disturbed. Furthermore, Cr (110) is strongly oriented by epitaxial growth. After cleaning a glass substrate with an outer diameter of 95 mm, an inner diameter of 25 mm, and a thickness of 1.27 mm, using a DC magnetron sputtering device,
After evacuation below 2 × 10 ^over 7 Torr, a glass substrate 300
After heating for 10 minutes at ℃, Ar gas was introduced, the gas pressure during discharge was maintained at 10 mTorr, and the input power was 500.
An intermediate film, a base film, a magnetic film, and a protective film were successively formed in this order under the conditions of W and a film forming rate of 180 A / min to prepare a thin film magnetic disk. When the film thickness of the underlying Cr film was 1000 A, CoCrTa of the magnetic film was 500 A, and Au was selected as the intermediate film, the film thickness was changed from 100 A to 3000 A.
The magnetic characteristics shown in Table 1 were obtained.

[0007]

[Table 1] When the film thickness of Au is 0 A (angstrom), that is, when there is no intermediate film, the coercive force is 490 Oe, which is very low. At 300 A, 1450 Oe can be obtained. Also, the coercive force squareness ratio S ^* is 0.6 due to the presence of the interlayer film.
It is improved from 8 to 0.82. As a result of elemental analysis in the depth direction of the film by Auger electron spectroscopy, oxygen diffuses into Cr when there is no intermediate film, whereas oxygen diffuses into the intermediate film when an intermediate film is used. C
It was found that it was not contained in the r film. This shows that the intermediate film has an effect of preventing oxygen from the glass from diffusing into Cr. Also, it was found by X-ray diffraction that the (111) plane of the Au film on the glass substrate was oriented parallel to the substrate surface, and the Cr film on it had a stronger (110) orientation than when there was no Au film. It was (Example 2) As in Example 1, various intermediate films, a base Cr film, a magnetic film, and a protective film were formed in this order on a glass substrate, and the magnetic characteristics were measured. The film thickness of the intermediate film was fixed at 500A.
As the magnetic film, a CoCrPt film of 500 A was formed.

[0008]

[Table 2] From this example, Cu, Rh, Pd, Ag, Ir, Pt, A
It can be seen that the coercive force is significantly improved by using the metal element of the metal film of u as the intermediate film. (Example 3) As in Example 1, an intermediate film, a base Cr film, a magnetic film, and a protective film were formed in this order on a glass substrate, and the magnetic characteristics were measured. As the magnetic film, a CoNiCr film of 500 A was formed, and the film thickness of the Cr underlayer film and the Pd intermediate film was changed.

[0009]

[Table 3] As is clear from the above example, the thickness of the Cr underlayer is 50.
In the case of 0 A or more, 1000 is obtained by providing an intermediate film.
A high coercive force of Oe or more can be obtained.

[0010]

According to the present invention, the crystal orientation and the crystal grain size of the Cr underlayer and the subsequent magnetic layer are controlled by selecting an appropriate material capable of obtaining a higher coercive force than the conventionally known intermediate film. A high coercive force of 1400 Oe or more can be obtained.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a magnetic recording medium according to an embodiment of the present invention.

[Explanation of symbols]

 11 non-magnetic substrate 12 intermediate film 13 Cr underlayer film 14 magnetic film

Claims (1)

[Claims] 1. A magnetic recording medium comprising a non-magnetic substrate such as glass, ceramics, carbon, etc., on which a base film such as Cr, a magnetic film and a protective film are laminated, and between the non-magnetic substrate and the base film such as Cr. Cu, Rh, Pd, Ag, Ir, Pt, A
A magnetic recording medium comprising a metal film containing at least one of u as a main component.