JPH103649A - Magnetic recording medium and method of manufacturing the same - Google Patents

Abstract

(57) Abstract: A magnetic recording medium having a recordable / reproducible magnetic film and a surface covered with a lubricating film, which reduces a frictional force generated between the medium and the magnetic head via a lubricant. A stable medium and high reliability of a magnetic recording / reproducing apparatus operating by a combination of a medium and a head are guaranteed. A non-magnetic support has a magnetic layer and a protective film,
In a magnetic recording medium coated with a lubricant on a protective film,
A magnetic recording medium wherein the oxygen concentration on the surface of the protective film is 10 atm% or less. By forming the lubricating film layer, even during long-term use, recording / reproducing errors can be generated, and stable running properties can be obtained without increasing the frictional force between the head and the medium. A magnetic recording medium and a recording / reproducing device with high performance can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus using a magnetic recording medium, and more particularly to a magnetic recording / reproducing apparatus.
The present invention relates to a magnetic recording medium having a magnetic thin film formed on a non-magnetic support by vapor deposition or the like.

[0002]

2. Description of the Related Art A magnetic recording / reproducing apparatus generally includes a magnetic recording medium such as a magnetic disk or a magnetic tape, a magnetic head, a driving mechanism, and a recording / reproducing circuit. A magnetic disk device having a magnetic layer formed on a disk is widely used as a large-capacity storage / reproduction device.

[0003] With the rise of high-density magnetic recording, a magnetic recording medium is used in which a continuous thin film is formed on a non-magnetic support by a technique such as sputtering or vapor deposition. These media have various advantages such as being able to increase the coercive force Hc and the residual magnetic flux density Br, as well as being able to reduce the thickness of the magnetic layer. However, there are drawbacks in terms of durability and running properties, and improvements are strongly demanded.

Therefore, in order to improve the durability and the running property, a hard protective film, for example, amorphous carbon is coated on the magnetic layer of the magnetic recording medium, and a perfluoropolyether (hereinafter, referred to as an amorphous carbon) is further coated thereon. "PFPE"
(Hereinafter referred to as a lubricant) is disclosed in JP-A-62-58414.

Further, in order to strongly adsorb the above-mentioned lubricant on the surface of the protective film, those having a functional group introduced into the lubricant molecule are available from various manufacturers (Audimont, Daikin Industries, etc.).
Supplied by In addition, a lubricant having a new functional group has been invented because a lubricant having an existing functional group has an insufficient adsorptivity, or, in other words, the durability and running properties of a magnetic recording medium are insufficient. I have. (JP-A-5-30195
4) On the other hand, in order to strongly adsorb the protective film surface using an existing lubricant, a heat treatment after applying the lubricant or an ultraviolet irradiation treatment is performed.

To adjust the surface of the protective film to strongly adsorb the lubricant on the surface of the protective film, see JP-A-2-16842.
Attempts such as 1 have been made.

[0007]

In order to meet the demand for higher recording density, a magnetic disk drive has a magnetic recording medium whose surface is smoothed, and the distance between a slider-shaped magnetic head and the medium (flying) is increased during recording and reproduction. Volume) can be reduced to 0.1 micron or less. In such a system, the frequency of contact between the medium and the head increases, and mechanical and thermal lubrication due to the contact increases. Due to the spin-off of the agent, the lubricant is not sufficiently supplied between the two units, and the durability and running properties such as the increase in the friction coefficient without maintaining low friction cannot be said to be sufficient with the conventional technology, and improvement is desired. ing.

In the heat treatment, which is one of the techniques for strongly adsorbing the lubricant on the surface of the protective film, there is a problem that during the treatment, the lubricant is greatly scattered due to decomposition and the thickness and quality of the lubricant cannot be controlled. is there. In addition, the lubricant is decomposed even in the ultraviolet treatment, and it is not possible to sufficiently absorb the lubricant on the surface of the protective film.

[0009] Further, it has been found that, in a use area at an extremely low flying height, a trace amount of metal atoms existing on the surface easily deteriorates the friction durability between the head and the disk or easily decomposes the lubricant in a frictional state. . Therefore, in order to maintain the durability of the head disk in an extremely low flying or contact state,
New improvement measures are needed.

An object of the present invention is to suppress mechanical and thermal spin-off of a lubricant, maintain low friction and maintain durability in an extremely low flying area between head media and a use environment where intermittent contact occurs. To provide an improved medium.

[0011]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has conducted detailed studies on the interaction between lubricant molecules and the surface composition of a protective film. It has been found that by lowering the composition ratio, the thermal stability of the lubricant can be maintained, and the magnetic recording medium having a protective film surface and a lubricating film layer formed thereon is compared with a conventional magnetic recording medium. It has been found that the present invention has excellent durability, and the present invention has been achieved.

That is, the present invention relates to a magnetic recording medium characterized in that the composition ratio of oxygen on the surface of the protective film before applying a lubricant is 10 atm% or less.

In order to realize the oxygen composition ratio of the protective film, the surface of the protective film is subjected to plasma treatment in a vacuum exhaust system by using hydrogen and a gas containing a hydrocarbon system such as CH4 and C2H6 as an introduction gas. It suppresses or reduces the oxygen concentration. Gases that can be used are H2, CH
4, hydrocarbon gas such as C2H6, Ar / H2, Ar / C
A mixed gas containing a substance according to the present invention such as H4 and Ar / N2 / H2 can be used. In addition, there is no limitation on hydrocarbon compounds that become liquid or solid at room temperature, as long as they can be introduced as gases into the evacuation system. However, since the purpose is to remove oxygen from the surface of the protective film, a compound containing oxygen is not preferable.

The composition ratio of the substance according to the present invention when using the mixed gas is 5% or more, preferably 20 to 50%.
%. As for the conditions for the plasma processing, it is necessary to adjust the gas pressure and the current density in consideration of the size of the evacuation system, the electrodes, and the processing time. When the compound according to the invention is used, it is possible to find a condition that the surface oxygen concentration is 10 atm% or less.

In particular, when a texture is formed on the protective film surface of the magnetic recording medium by using a resist by patterning in a dot shape or the like, the film quality of the protective film is not changed as much as possible, and the oxygen is reduced by a high etching rate. May be used. In the composition ratio of the protective film surface after being etched by oxygen, the oxygen concentration reaches 20 atm% or more, and when a lubricant is applied thereon, the decomposition and scattering of the lubricant due to heat can be performed without etching the lubricant. Scatters more than 20% as compared with the case of coating, and the durability and running properties of the magnetic recording medium are significantly reduced. Even in such a case, using the manufacturing method of the present invention is particularly effective because the oxygen concentration on the surface of the protective film can be reduced. Forming irregularities on a non-magnetic support is not preferable from the viewpoint of increasing the recording density, and it is necessary to form irregularities with a protective film above the magnetic material.

The form of the magnetic recording medium used may be any of a tape, a disk, a card and the like.

As a material of the nonmagnetic support, Al alloy,
Examples include Ti alloy, glass, ceramic, and plastic.

The material of the magnetic film is a metal such as Fe, Co or Ni, a Co alloy such as Co-Ni or Co-Cr, an Fe oxide or a Cr oxide.

The material of the protective film is graphite, diamond or amorphous carbon, SiC,
Carbides such as TiC; and nitrides such as BN and C3N4. When forming the protective film, even if the surface or the entire protective film is formed by using the gas used in the present invention as an assist, an equivalent one having a low surface oxygen concentration can be obtained. However, as the thickness of the protective film is reduced, the film forming conditions for obtaining sufficient properties as the protective film may be limited. More preferred.

The lubricant used is, for example, a terminal-modified perfluoropolyether, such as Fomblin Z-DOL, Fombl.
inAM 2001, Demnunm SA and the like. These lubricants show high thermal stability in bulk, but for thin films of the order of a few nm, such as those applied on magnetic recording media, greatly depend on the chemical properties of the surface on which they are applied. On a surface with a lot of oxygen, its thermal stability is significantly reduced,
The degradation of the terminally modified portion and the main chain portion was found in the process leading to the present invention. Therefore, in the heat treatment after coating performed in order to strongly adsorb the lubricant on the protective film surface, the surface formation of the present invention is particularly effective from the aspect of dissolving and scattering of the lubricant, and the lubricant is applied to the protective film. A strong adsorption layer of molecules can be formed sufficiently.

Since the magnetic recording medium according to the present invention has a low oxygen composition ratio on the surface of the protective film, it exhibits good stability of the lubricant. , The coefficient of friction is kept smaller than that of the conventional device, and a highly durable device can be realized.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

Embodiment 1 FIG. 1 is a sectional view of a hard disk as an example of a magnetic recording medium according to the present invention.
In the figure, 5 is a protective film layer, and 6 is a lubricating film layer.

A sample disk as shown in FIG. 1 was prepared by the following steps. A Ni—P plating layer is formed as a hard underlayer 2 on an Al—Mg alloy substrate 1, a nonmagnetic Cr layer 3 is provided thereon, and a Co alloy magnetic film 4 is provided thereon.
And a carbon film was formed thereon as a hard protective film 5. Next, H2 gas was introduced and the gas pressure was 100 mT.
Plasma treatment was performed for 10 seconds at orr and 200 W output. As a lubricant, Fomblin AM2001 was applied. After application, 1
Heat treatment was performed at 20 ° C. for 2 hours.

(Embodiment 2) The gas in the plasma processing portion was changed to Ar / H2 (20%) and the gas pressure was 100 mTorr,
Plasma processing was performed at an output of 200 W for 10 seconds. Otherwise, a sample disk was prepared in the same manner as in Example 1.

(Embodiment 3) The gas in the plasma treatment was changed to Ar / CH4 (10%), and the gas pressure was 300 mTorr.
r, plasma processing was performed at an output of 50 W for 10 seconds. Otherwise, a sample disk was prepared in the same manner as in Example 1.

Example 4 A protective film was formed in the same manner as in Example 1, the surface of the protective film was masked with a resist, and a dot-like texture was formed by etching with oxygen. As a plasma treatment after the etching, Ar / H2 (20%) was used for 10 seconds at a gas pressure of 300 mTorr and an output of 200 W. After removing the resist, a lubricating film was formed in the same manner as in Example 1.

Comparative Example 1 A sample was prepared in the same manner as in Example 1, except that only the plasma treatment was omitted.

Comparative Example 2 The gas in the plasma treatment was changed to Ar, and the gas pressure was changed to 100.
Plasma treatment was performed at mTorr and an output of 200 W for 10 seconds. Otherwise, a sample disk was prepared in the same manner as in Example 1.

Comparative Example 3 The gas in the plasma treatment was changed to O2, and the gas pressure was changed to 300.
Plasma treatment was performed at mTorr and an output of 50 W for 3 seconds. Otherwise, a sample disk was prepared in the same manner as in Example 1.

With respect to the sample disks obtained in Examples 1 to 4 and Comparative Examples 1 to 3, the residual ratio was measured before and after the heat treatment after the application of the lubricant in order to evaluate the scattering property of the lubricating film. In addition, the composition of the surface of the protective film before applying the lubricant was changed to ES
CA (Electron Spectoroscopy for Chemical)
Analysis), and the oxygen concentration on the surface was obtained.

In the analysis of surface elements by ESCA, the depth of the information to be included depends on the incident angle of the X-rays. Becomes The surface oxygen concentration shown in FIG. 2 is based on ESCA, and the incident angle is 75 degrees.
Therefore, it is considered that the information includes information up to about 7 nm from the surface. The oxygen concentration defined in claim 1 indicates an analysis result by ESCA, and indicates a composition ratio with respect to a surface composition composed of an element detected at 0.1 atm% or more. Carbon is Bindig Energy (hereinafter abbreviated as BE)
Since it has a main peak at 284.5 eV, it is 281 to 29
Sensitivity Factor (hereinafter referred to as S)
F) (abbreviated as F) is calculated as 0.296.
8 to 540 eV, SF = 0.711, BE = 3 for nitrogen
96 to 404 eV, SF = 0.377, cobalt is B
E = 775-790 eV, SF = 2.142, platinum is
BE = 68 to 79 eV, SF = 4.674, and argon was used to calculate the composition ratio using BE = 238 to 248 eV and SF = 1.0011.

FIG. 2 shows the relationship between the oxygen concentration on the protective film surface and
It shows the residual ratio of the lubricating film after the heat treatment. As can be seen from the figure, in Examples 1 to 4 of the present invention, the surface oxygen concentration is low and the residual ratio of the lubricating film is high. On the other hand, Comparative Example 1
In Nos. 3 to 3, the surface oxygen concentration is high, the residual ratio of the lubricating film is low, and the stability of the film is poor.

Examples 1, 2, 3, 4 and Comparative Example 1,
In order to examine the change in the coefficient of friction by the CSS test on the sample disks obtained in 2, 3
The recording was performed 000 times, and then the head was gently left on the disk for about 6 hours to measure the sexual friction force at the start of rotation of the disk. The result is shown in FIG. The product according to the example has a lower static friction force than the comparative example. According to the present invention, even when CSS is performed, the lubricant is adsorbed on the surface of the protective film, so that the increase in frictional force is small even during CSS, and the spin-off of the lubricant is small even if left after the test for the above-described reason. It is considered that there is no suction between the head disks.

Thus, it can be seen that the medium according to the present invention is suitable for a medium used at an extremely low flying height suitable for a high recording density medium.

Further, the magnetic recording medium according to the present invention was incorporated in a recording / reproducing apparatus, and a signal recording / reproducing test was performed. Even if the test was continued for one month or more, no recording / reproducing error occurred, and a head-to-disk error occurred. No increase in friction coefficient and no adsorption phenomenon were observed, and no trouble was observed in the operation of the device. The residual ratio of the lubricating film thickness after the operation was also improved by about 20% as compared with the conventional case. As described above, the medium according to the present invention has a sufficiently small spin-off of the lubricant for use in a magnetic recording / reproducing apparatus.

[0037]

According to the magnetic recording medium of the present invention, since the chemical composition of the interface between the protective film surface and the lubricating film is optimized, the lubricating property can be maintained for a long time.
A high recording density magnetic recording medium and a recording / reproducing apparatus having excellent sliding resistance are provided.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a basic configuration of a magnetic recording medium according to the present invention.

FIG. 2 is a diagram showing stability of a lubricant with respect to oxygen concentration in a magnetic recording medium according to the present invention.

FIG. 3 is a table showing CSS test results of Examples and Comparative Examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Al-Mg alloy substrate, 2 ... Hard underlayer, 3 ... Underlayer (Cr etc.), 4 ... Co-based magnetic film, 5 ... Hard protective film, 6 ... Lubrication film.

Claims (5)

[Claims] A magnetic layer and a protective film on a non-magnetic support,
In a magnetic recording medium coated with a lubricant on a protective film,
A magnetic recording medium wherein the oxygen concentration on the surface of the protective film is 10 atm% or less. 2. A non-magnetic support having a magnetic layer and a protective film on a non-magnetic support,
In a magnetic recording medium coated with a lubricant on a protective film,
A magnetic recording medium, wherein a plasma treatment is performed on the surface of the protective film with a mixed gas containing hydrogen or a hydrocarbon compound, or a single gas. 3. A non-magnetic support having a magnetic layer and a protective film on a non-magnetic support,
In a magnetic recording medium coated with a lubricant on a protective film,
A method for manufacturing a magnetic recording medium, comprising: plasma-treating the surface of a protective film with a mixed gas containing hydrogen or a hydrocarbon gas, or a single gas. 4. A magnetic recording / reproducing apparatus using the magnetic recording medium according to claim 1. 5. A magnetic recording / reproducing apparatus using the magnetic recording medium according to claim 2.