JPH01138611A - Magnetic disk - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a magnetic disk and to decrease surface friction by providing a protective film formed of a diamond-like carbon film on a substrate on which a magnetic film is provided and providing a reformed layer by fluorine plasma or fluorine ions on the surface thereof. CONSTITUTION:The protective film 15 formed of the diamond-like carbon film is provided on the Al substrate 11 on which at least the magnetic film 13 is provided. The surface reformed layer 16 by the fluorine plasma or fluorine ions is formed on the surface of this protective film 16. A thin silicon film 14 is provided between the protective film 15 and the magnetic film 13 to enhance the adhesiveness between the protective film 15 formed of the diamond- like carbon film and the magnetic film 13 if said adhesiveness is poor. The high-performance magnetic disk improved in the wear resistance and lubricity of the magnetic disk is obtd. by forming the reformed layer of the fluorine plasma or fluorine ion extremely thinly on the surface of the diamond-like carbon film 15 in such a manner.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk, and particularly to a magnetic disk having a protective coating on its surface.

[Prior Art] In order to use the space occupied by a magnetic disk as effectively as possible, it is necessary to increase the recording density of information as much as possible. However, for this purpose, the distance between the magnetic head and the magnetic disk must be made as small as possible.

As a result, collisions and wear between the magnetic head and the magnetic disk inevitably increase, so it is necessary to provide a protective film to protect the information on the magnetic disk.

In conventional magnetic disks, a relatively hard 5i02 thin film is used as a protective film, and a lubricating layer of an organic solvent is provided thereon to reduce the coefficient of friction on the surface.

[Problems to be Solved by the Invention] However, with the combination of 5i02 as a protective film and an organic lubricant layer used in conventional magnetic disks as described above, the distance between the magnetic head and the magnetic disk becomes narrow. In this case, since the material of the protective film has a lower hardness than the material used for the magnetic head, the wear resistance will be reduced by 1q. Furthermore, since the lubricating layer of organic solvent applied to the surface is liquid, there are problems such as drying and adhesion to the head.

The present invention was made in order to solve the conventional problems as described above, and has two excellent wear resistance,
An object of the present invention is to provide a magnetic disk having a protective coating with reduced friction on the surface.

[Means for Solving the Problems] In the present invention, a protective film made of diamond-like carbon is provided on a substrate provided with at least a magnetic film, and the surface of the protective film is treated with fluorine plasma or fluorine ions. This is a magnetic disk characterized in that it is provided with a modified layer of.

In the present invention, if the adhesion between the protective coating and the magnetic film is poor, it is preferable to provide a silicon thin film between the protective coating and the magnetic film.

Furthermore, it is desirable that the above-mentioned protective coating be provided over the entire surface of the magnetic film.

[Function] Although the diamond-like carbon film has an amorphous structure containing hydrogen, its hardness is close to that of a diamond crystal, and its Young's modulus is also comparable to that of a diamond crystal. However, the closer it is to diamond, the more the friction coefficient of the surface is 0.
It is a fairly large value of 5 or more. The diamond-like carbon film contains a lot of hydrogen, and many carbon and hydrogen bonds can be seen on its surface. The bond between carbon and hydrogen exhibits hydrophobicity, which is thought to be the reason for the large coefficient of friction. On the other hand, the friction coefficient can be reduced to 0.05 or less by modifying only the extreme surface layer of the diamond-like carbon film into a hydrophilic layer by fluorine plasma, fluorine ion implantation, or the like. In the present invention, by forming an extremely thin modified layer using fluorine plasma or fluorine ions on the surface of a diamond-like carbon film, a high-performance magnetic disk can be obtained because it has both wear resistance and lubricity. .

In addition, when a silicon thin film is provided on a magnetic film, the adhesion strength between the magnetic film and the carbon film is dramatically improved, so the carbon film can be formed as a protective coating on any magnetic film, and the carbon film itself can be Characteristics can be used effectively.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. Ni on the surface
On the N substrate 11 on which the P film 12 and the magnetic film 13 made of Co, Co--Cr, etc. have been sequentially formed, a thin silicon film 14 of 100 Å or less is formed by sputtering, vacuum evaporation, cluster ion beam, etc. to improve the adhesion between the carbon film and the magnetic film. formed in order to increase The above substrate is placed on the negative electrode of a parallel plate electrode in a vacuum chamber. First, the inside of the vacuum chamber is set to 1O-6 Torr.
After reducing the vacuum to r or less, methane gas and hydrogen gas are introduced. The mixing ratio of methane and hydrogen is in the range of 0.1 to 5%,
Adjust the pressure to 0.1-10 Torr. Thereafter, a discharge voltage of about 250 to 350 V and a discharge current of about 0.1 to 1 mA/ctn are applied between the parallel plate electrodes in the vacuum chamber to generate a DC glow discharge.The plasma is generated for 1 minute. Generate approximately 200 diamond-like carbon thin films 1
form 5. At this point, the Vickers hardness of the surface is 1
It is about 0000Kg/#n2, but when the dynamic friction coefficient is measured, it is a large value of 0.5 or more. Next, the substrate on which the diamond-like carbon thin film 15 is formed is left as it is, and fluorine gas is introduced to generate a DC glow discharge. The thickness of the surface modified layer 16 formed at this time is several tens of amps.
It is. The coefficient of dynamic friction of the surface of the film obtained as described above was measured and found to be 0.05 or less. A protective film was also formed on the back side using the same process as above.

15 on the surface of the magnetic disk formed using the method described above.
Repeated contact-floating test (so-called CO
When a ntact-start-stop test was performed, no scratches were observed on the surface even after 100,000 times or more.

In the above examples, carbon films were synthesized by DC glow discharge CVD, but substantially similar films were also obtained by RF plasma CVD, ion blating, ion beam sputtering, etc. using the same gas. In addition, in this embodiment, DC
Although the electrodes in glow discharge have a parallel plate structure, similar results can be obtained in a structure in which the anode and cathode electrodes do not face each other.

[Effects of the Invention] As explained above, in the magnetic disk of the present invention, a diamond-like carbon film with excellent wear resistance is used as a protective coating, and a fluorine-modified layer is provided on the surface of the diamond-like carbon film. Since the coefficient of friction on the surface is significantly reduced, the magnetic film can be sufficiently protected and the friction on the surface can be minimized, making it possible to provide a high-performance magnetic disk.

Furthermore, if a silicon film is provided between the magnetic film and the carbon film, the adhesion between the two will improve, so if this is utilized, the carbon film can be formed on any magnetic film.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention. 11...M substrate 12...NiP film 1
3...Magnetic film 14...Silicon film 15...Diamond-like carbon thin film 16...Surface modified layer

Claims (2)

[Claims] (1) A protective film made of diamond-like carbon is provided on at least the substrate on which the magnetic film is provided, and a modified layer using fluorine plasma or fluorine ions is provided on the surface of the protective film. Features a magnetic disk. (2) The magnetic disk according to claim 1, wherein a silicon thin film is provided between the magnetic film and the protective coating.