JPH06309656A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a magnetic recording medium avoiding the attraction and crash of a magnetic head and excellent in recording sensitivity. CONSTITUTION:An underlayer 2, a magnetic layer 3, a protective layer 4 and a lubricant layer 6 are laminated on a substrate 1. The protective layer 4 contains Ta and has fine protrusions 5 formed by ion etching on the surface. In order to form the fine protrusions 5, the protective layer 4 preferably contains >=20wt.% Ta. The height of the fine protrusions 5 is preferably regulated to >=10nm so as to avoid crash and the thickness of the protective layer 4 including the height of the fine protrusions 5 is preferably regulated to >=60nm.

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 suitable for high density recording.

[0002]

2. Description of the Related Art Generally, a magnetic recording medium of this kind is provided with an electroless plating layer such as Ni-P on the surface of a non-magnetic aluminum alloy substrate, and Co-N is formed on the surface by a sputtering method or the like.
A magnetic layer made of a thin film such as an i alloy is provided. Usually, in order to avoid adsorption of the magnetic head and the magnetic recording medium and crash of the magnetic head, the substrate surface is physically roughened in advance by texture processing, or disclosed in JP-A-3-44817. As described above, a method has been adopted in which a resin thin film layer containing fine particles such as aluminum and titanium is provided on the substrate surface to form a large number of minute protrusions on the substrate surface.

[0003]

However, the above-described conventional magnetic recording medium is disadvantageous in reliability and cost, and there is room for improvement in recording sensitivity.

An object of the present invention is to obtain a magnetic recording medium which is free from attraction with a magnetic head or head crash and which has excellent recording sensitivity at low cost.

[0005]

According to the present invention, a magnetic layer is formed without processing the surface of a substrate, and T is formed on the magnetic layer.
There is provided a magnetic recording medium in which a protective layer containing a is provided and the surface of the protective layer is etched by ion etching to form fine protrusions on the surface of the protective layer. The height of the fine protrusions must be at least 10 nm or more to avoid crashes, and the thickness of the protective layer should be 60 nm including the height of the fine protrusions.
It is desirable that the thickness is not less than nm. Further, unless the Ta content is 20% by weight or more, it is difficult to etch the protective layer into a columnar shape.

[0006]

According to the above magnetic recording medium, the minute protrusions on the surface of the protective layer effectively prevent the magnetic head from adhering to the magnetic recording medium and the occurrence of head crush. Further, by including Ta in the protective layer, a uniform surface can be formed without increasing the film thickness as compared with the conventional graphite or the like, so that a highly sensitive recording medium can be manufactured. On the other hand, unlike a method of directly physically roughening a substrate or coating and forming a resin thin film having fine protrusions on a substrate, after forming a film containing Ta, in the same chamber or Since the surface can be roughened only by ion etching in the same apparatus, it is advantageous in terms of cost. In addition, since the fine protrusions are formed after the magnetic layer is formed and do not bring the protrusions into the magnetic layer itself, a uniform magnetic layer is maintained, so that excellent reliability is obtained and recording sensitivity is also improved.

[0007]

The present invention will be described in detail with reference to the following examples. FIG. 1 is a schematic sectional view showing an example of a magnetic recording medium according to the present invention. In the figure, 1 is a substrate made of Al alloy, 2 is a Cr underlayer formed on the substrate 1 by a sputtering method, 3 is a CoNi magnetic layer formed on the surface of the underlayer 2 by a sputtering method, 4 is a protective layer made of Ta provided on the surface of the magnetic layer 3, 5 is a fine projection formed on the surface of the protective layer by ion etching, and 6 is a lubricant layer made of perfluoroalkyl polyether.

As the substrate 1, besides Al alloy, glass or the like may be used. The base layer 2 on the substrate has a thickness of about 300 to 50.
It may be 0Å, and a plating layer such as Ni-P may be used. The magnetic layer 3 is not only a thin film formed by sputtering CoNi but also CoN.
A thin film obtained by a sputtering method such as iP or CoNiCr or a plating method may be used. A suitable thickness is about 400-600Å. The protective layer 4 is a thin film containing at least 20% by weight of Ta and having a thickness of about 300 to 500Å by the sputtering method. Graphite or the like is suitable as the protective layer material to be mixed. The surface of this protective layer is ion-etched (R
It has fine protrusions 5 formed by etching with IE (reactive ion etching) or the like. Ta is columnar etched. The etching amount is about 300 to 500Å. When etching by RIE, a mixed gas of Cl ₂ and CCl ₂ is suitable as an etching gas. A lubricant such as perfluoroalkyl polyether is further applied to the surface of the minute protrusions to form a lubricant layer 6.

Examples 1 to 10 and Comparative Examples 1 to 2 A sample in which an underlayer and a magnetic layer having the following formulation were sequentially provided on a substrate made of an Al alloy was used as a constant, and a Ta film was formed on the magnetic layer. The thickness (the thickness of the protective layer) and the height of the fine protrusions were changed, and 10 types of magnetic recording media were further manufactured depending on whether the lubricant was applied or not, and Examples 1 to 10 were prepared. Two types of Comparative Examples 1 and 2 were prepared by applying a lubricant to a protective layer made of graphite and having a thickness of 500Å.

Regarding these 12 kinds of magnetic recording media,
The magnitude of the current required for the magnetic head to write on the recording medium was measured and the CSS test was conducted. The measurement results are shown in Table 1. Here, the CSS (Contact Start Stop) test is to see if the magnetic head crashes due to the adsorption of the media surface and the head surface, and the media is not scratched. The head is placed, then the medium is rotated to float the head, then the medium is stopped, and this is repeated tens of thousands of times.

[0011]

[Table 1] ┛

As is clear from Table 1, in the example, a thinner protective layer can be obtained than in the comparative example, and the required write current can be made extremely small. Moreover, CSS
The number of times the test can be endured is far greater.

[0013]

As described above, according to the magnetic recording medium of the present invention, the protective layer provided on the magnetic layer contains Ta, and the surface of the protective layer is etched by ion etching to form fine projections. Adhesion with the head and occurrence of head crash can be avoided, and the recording sensitivity can be improved. Also, unlike the method of texturing the surface of the substrate or coating and forming a resin layer having minute protrusions, the minute protrusions are formed only by etching in the same chamber immediately after forming the film, which is cost-effective. A magnetic recording medium which is advantageous and has excellent reliability in which a protrusion is formed after the magnetic layer is formed and which has a uniform magnetic layer is obtained.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Substrate 2 Underlayer 3 Magnetic layer 4 Protective layer 5 Microprojections 6 Lubricant layer

Claims (3)

[Claims] 1. A magnetic recording medium in which at least a magnetic layer and a protective layer are provided on a substrate, wherein the protective layer contains Ta and has fine projections formed by ion etching on the surface of the protective layer. And a magnetic recording medium. 2. The magnetic recording medium according to claim 1, wherein the protective layer has a thickness of 60 nm or more. 3. The magnetic recording medium according to claim 1, wherein the Ta content of the protective layer is 20% or more.