JPH07249222A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium capable of isotropically attaining such magnetic characteristics as high coercive force and a high squareness ratio, adaptable to lower the floating height of a magnetic head and excellent in CSS resistance. CONSTITUTION:Dispersedly distributed protrusions are formed on a nonmagnetic substrate 1 such as a glass substrate with nonmagnetic metal oxide deposits 6 and a ruggedness controlling layer 7 made of a carbon film is formed by sputtering on the protrusions. A nonmagnetic metallic underlayer 2, a magnetic layer 3 and a protective layer 4 are successively formed by sputtering on the ruggedness controlling layer 7 and a lubricative layer 5 is formed on the protective layer 4 to produce the objective magnetic recording medium whose surface reflects the surface roughness of the ruggedness controlling layer 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium mounted on a fixed magnetic disk device used as an external storage device of an information processing device such as a computer.

[0002]

2. Description of the Related Art In recent years, fixed magnetic disk devices have been widely used as external storage devices for information processing devices such as computers. As shown in FIG. 4, a conventional magnetic recording medium mounted on this fixed magnetic disk device has a non-magnetic base layer 1, a non-magnetic metal underlayer 2, a thin magnetic layer 3 made of a ferromagnetic alloy, and a magnetic layer 3 made of a ferromagnetic alloy. A protective layer 4 is sequentially formed, and a lubricating layer 5 made of a liquid lubricant is further provided on the protective layer 4.

As the non-magnetic substrate 1, for example, a mirror-polished glass substrate is used. This non-magnetic substrate 1 is heat-treated in a vacuum chamber to a temperature of 300 ° C., and then C
a non-magnetic metal underlayer 2 made of r and having a film thickness of 1000 Å, Co
A magnetic layer 3 made of 80 at%, 14 at% Cr, and 6 at% Pt and having a film thickness of 500 Å and a protective layer 4 made of aC (amorphous carbon) and having a film thickness of 200 Å are sequentially deposited by sputtering. Then, a fluorocarbon-based liquid lubricant is applied on the protective layer 4 to form a lubricating layer 5 having a film thickness of 20Å, whereby a magnetic recording medium is manufactured.

The magnetic recording medium manufactured in this manner has good mechanical properties such as strength and dimensional accuracy without any practical problems, and the magnetic properties are such that the coercive force Hc is about 1600 Oe, the residual magnetic flux density and the magnetic layer. Br · δ, which is the product of the film thickness, is as good as about 400 G · μm.

[0005]

In recent years, due to the rapid increase in the amount of information and the diversification of information, it is necessary to perform a large amount of information processing, so that the fixed magnetic disk drive is required to have a high recording density and a large capacity. There is a strong demand. Therefore, even in the magnetic recording medium used in the fixed magnetic disk device, in order to cope with high recording density and large capacity, high coercive force,
There is a need for a medium having a high squareness ratio and isotropic magnetic characteristics, capable of reducing the flying height of a magnetic head, and having good CSS durability.

However, in a magnetic recording medium using a conventional substrate made of a glass substrate, which has excellent surface smoothness and can reduce the flying height of the magnetic head, since the surface of the substrate is smooth, the squareness of the magnetic characteristic is obtained. There is a problem that the ratio is remarkably poor and that it is difficult to achieve a high coercive force because the substrate contains oxygen. Furthermore, there was a problem with CSS durability.

The present invention has been made in view of the above problems, and isotropic magnetic properties having a high coercive force and a high squareness ratio can be realized, and further, it is possible to reduce the flying height of a magnetic head. Another object is to provide a magnetic recording medium having excellent CSS durability.

[0008]

According to the present invention, the above-mentioned problems are obtained by sequentially laminating a non-magnetic metal underlayer, a thin-film magnetic layer made of a ferromagnetic alloy, a protective layer, and a lubricating layer on a non-magnetic substrate. In the magnetic recording medium, irregularities that are discretely distributed by the nonmagnetic metal oxide deposit are formed between the nonmagnetic substrate and the nonmagnetic metal underlayer, and a carbon film formed by the sputtering method on the irregularities. This is solved by providing a magnetic recording medium in which the unevenness control layer made of is formed, and the surface roughness of the unevenness control layer is reflected even on the surface of the lubricating layer.

Examples of the non-magnetic substrate include a glass plate, a ceramics plate, an aluminum plate, a titanium plate, a carbon plate and a silicon plate. Among them, the glass plate is preferable because it has a high surface smoothness and can be obtained at a low cost. It is suitable. Examples of non-magnetic metal oxides include In and S
n, Zr, Al, Cu, Ta, Ti, Si, Cr, Fe
Among these, oxides of one kind of metal selected from the above or oxides of alloys of two or more kinds of metals are preferably used. As a specific example, ITO (Indium-Tin-Oxid)
e), SnO ₂ , ZrO _{2 and the} like.

[0010] The surface roughness of the unevenness control layer made of a carbon film to not 5nm center line average roughness R _a is preferably in the range of 15 nm.

[0011]

Function: Discrete unevenness is formed by discretely depositing a non-magnetic metal oxide on a non-magnetic substrate having a smooth surface such as glass, and an unevenness control layer made of a carbon film is further formed thereon. And a non-magnetic metal underlayer,
By forming the magnetic layer by sputtering, high coercive force,
A magnetic layer that isotropically achieves a high squareness ratio and a high coercive force squareness ratio can be formed, and a magnetic recording medium having excellent magnetic characteristics can be obtained.

Further, the size of the above-mentioned metal oxide deposit,
Properly select the degree of discreteness to form irregularities, select the film thickness of the irregularity control layer made of carbon formed on it appropriately, and set the surface roughness of the irregularity control layer to the surface of the lubricating layer that is the medium surface. By reflecting it, the surface roughness of the medium can be appropriately controlled, the flying height of the magnetic head can be reduced, and a magnetic recording medium excellent in CSS durability can be obtained.

Further, the unevenness control layer made of carbon also acts as a buffer layer for blocking oxygen of the metal oxide, and the magnetic characteristics can be improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing the structure of an embodiment of a magnetic recording medium according to the present invention. A nonmagnetic metal oxide deposit 6 and a carbon unevenness control layer 7 are provided between the nonmagnetic substrate 1 and the nonmagnetic metal underlayer 2. Since other configurations are similar to those of the conventional magnetic recording medium described above, common parts are denoted by the same reference numerals and description thereof is omitted.

In the magnetic recording medium of this embodiment, first, the surface of a disk-shaped non-magnetic substrate 1 made of glass which has been subjected to inner and outer diameter processing and surface cutting is subjected to ultra-precision surface polishing, followed by precision cleaning, and then a non-magnetic metal. CVD of ITO as oxide deposit 6
It is formed by the method. Next, the deposition chamber pressure was set to 0.7 Pa in Ar gas atmosphere using a magnetron sputtering apparatus, and the substrate 1
After heating to a temperature of 300 ° C., while applying a DC bias of 200 V to the substrate 1, carbon is sputtered on the metal oxide deposit 6 to form an unevenness control layer 7 having a film thickness of 500 Å, which is further laminated. A non-magnetic metal underlayer 2 made of Cr and having a film thickness of 1000 Å 2, Co80at% -Cr14at%
A magnetic layer 3 made of a ferromagnetic alloy of −Pt 6 at% and a thickness of 500 Å, and a protective layer 4 made of aC and having a thickness of 200 Å are sequentially formed by sputtering. Then, a fluorocarbon liquid lubricant is applied on the protective layer 4 to form a lubricating layer having a film thickness of 20 Å to obtain the magnetic recording medium shown in FIG.

2 and 3 show the results of observing the surface of the magnetic recording medium with an AFM (atomic force microscope).
FIG. 2 shows a medium in which only the non-magnetic metal oxide deposit 6 (ITO) is provided between the non-magnetic substrate 1 and the non-magnetic metal underlayer 2, and the surface roughness is the center line average roughness. _Ra 4n
It was m. FIG. 3 shows a medium in which a nonmagnetic metal oxide deposit 6 (ITO) and a carbon unevenness control layer 7 are provided between a nonmagnetic substrate 1 and a nonmagnetic metal underlayer 2, and the surface roughness thereof is _Ra was 7 nm. By controlling the film thickness of the unevenness control layer 7, the surface roughness _Ra is 5 nm.
It is possible to control in the range of ~ 15 nm, and the film thickness is 500
At the time of Å, the best CSS durability is shown at _Ra 7 nm.

[0017]

As described above, in the magnetic recording medium according to the present invention, the unevenness which is discretely distributed by the nonmagnetic metal oxide deposit is formed on the nonmagnetic substrate, and the sputtering method is further formed thereon. A concavo-convex control layer made of the carbon film formed in step (4) is formed, and a non-magnetic metal underlayer is formed on the concavo-convex control layer, and the surface roughness of the concavo-convex control layer is the surface of the lubricating layer which is the surface of the magnetic recording medium. It is characterized by being reflected up to. By adopting such a configuration, it is possible to achieve isotropic magnetic characteristics of high coercive force, high squareness ratio, and high coercive force squareness ratio, and further, it is possible to cope with a low flying height of the magnetic head and further, CSS durability. It becomes possible to obtain an excellent magnetic recording medium. Therefore, by using such a magnetic recording medium, it is possible to reduce the bit length and the track width in an information storage device such as a fixed magnetic disk device, and it is possible to realize a large-capacity storage device having a high information recording density.

As the non-magnetic metal oxide, In, S
n, Zr, Al, Cu, Ta, Ti, Si, Cr, Fe
Among these, oxides of one kind of metal selected from the above or oxides of alloys of two or more kinds of metals are preferably used. Further, when the surface roughness of the unevenness control layer made of carbon is in the range of 5 nm to 15 nm in terms of the centerline average roughness Ra, _a low flying height of the magnetic head can be realized, and good CSS durability and magnetic characteristics can be obtained. Is suitable.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing the configuration of an embodiment of a magnetic recording medium according to the present invention.

FIG. 2 A of the surface of a magnetic recording medium prepared by providing only non-uniformity of non-magnetic metal oxide deposits on a non-magnetic substrate
Observation view by FM

FIG. 3 is an AFM observation view of the surface of a magnetic recording medium produced by providing discrete unevenness of a non-magnetic metal oxide deposit on a non-magnetic substrate and further providing an unevenness control layer made of carbon on the unevenness.

FIG. 4 is a schematic cross-sectional view showing the configuration of a conventional magnetic recording medium.

[Explanation of symbols]

 1 non-magnetic substrate 2 metal underlayer 3 magnetic layer 4 protective layer 5 lubricating layer 6 metal oxide deposit 7 unevenness control layer

Claims (3)

[Claims] 1. A magnetic recording medium comprising a non-magnetic substrate, a non-magnetic metal underlayer, a thin film magnetic layer made of a ferromagnetic alloy, a protective layer, and a lubricating layer, which are sequentially laminated on the non-magnetic substrate. The unevenness that is discretely distributed by the deposit is formed, and the unevenness control layer made of a carbon film formed by a sputtering method is further formed on the unevenness, and the surface roughness of the unevenness control layer is the above-mentioned. A magnetic recording medium characterized by being reflected even on the surface of a lubricating layer. 2. The non-magnetic metal oxide is In, Sn, Zr,
2. The magnetic material according to claim 1, which is an oxide of one kind of metal selected from Al, Cu, Ta, Ti, Ti, Si, Cr and Fe or an oxide of an alloy composed of two or more kinds of metals. recoding media. 3. A surface roughness of an unevenness control layer made of a carbon film.
Is the center line average roughness R _aIn the range of 5 nm to 15 nm
Magnetic recording according to claim 1 or 2, characterized in that
Medium.