JPS61131224A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability of the titled magnetic recording medium and a magnetic head without deteriorating vertical magnetic recording characteristics by forming an amorphous thin film contg. Si, Zr, and O on a recording magnetic layer having vertical magnetic anisotropy. CONSTITUTION:A recording magnetic layer 12 of Co-Cr, etc. having vertical magnetic anisotropy is formed on a base body 11 such as a plastic film, and an Si-Zr-O amorphous thin film 13 is formed in 60-100 Angstrom thickness on the layer 12 by high-frequency sputtering with silicon nitride and ZrO2 as the targets to obtain a protective layer. A lubricating layer 14 of a fluorocarbon lubricant can be further formed on the layer 3. The protective layer 13 has excellent resistance to abrasion and corrosion, and is durable even with thin thickness. The layer is also firmly adhered to the magnetic layer 12, and the lubricating layer 14 can be held surely. Consequently, an excellent magnetic recording medium having small spacing loss can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a magnetic recording medium, and particularly to a magnetic recording medium provided with a recording magnetic layer having perpendicular magnetic anisotropy.

[Technical background of the invention and its problems]

In recent years, with the development of information processing technology, the amount of information carried by memory devices has increased dramatically, and the demand for larger capacities for magnetic recording media such as floppy disks has also increased. In order to meet this demand, research and development has been actively conducted on magnetic recording media capable of high-density recording, particularly magnetic recording media for perpendicular magnetic recording that performs recording using magnetization perpendicular to the film surface. ing. A magnetic recording medium for perpendicular magnetic recording is a medium equipped with a recording magnetic layer that has perpendicular magnetic anisotropy, and is different from the coated media that constitutes most of the magnetic recording media for in-plane recording currently in practical use. Metal thin film media in which a thin metal film such as a Co-Cr alloy is formed as a recording magnetic layer by sputtering or vapor deposition, or oxide thin film media with a magnetoplumbite crystal structure such as Ba ferrite or Sr ferrite are highly popular. It is seen as a promising medium that is more suitable for density recording.

By the way, in coated media, the recording magnetic layer is formed by mixing magnetic powder with a binder etc. and coating it on the substrate, so the recording magnetic layer has elasticity, and it is also possible to mix a lubricant into the magnetic layer. It is also possible to maintain good contact between the medium and the magnetic head, thereby ensuring sufficient durability of the medium and the head.

On the other hand, in metal thin film media and oxide thin film media, the recording magnetic layer has almost no elasticity, so when a magnetic head made of hard material such as ferrite runs over the medium, the surface of the medium Damage such as scratches is more likely to occur. In that case, not only will the durability of the media and head be impaired, but the effective distance between the media and head will increase due to adhesion of abrasion particles from the media and head, resulting in a large spacing loss and frequency characteristics. This can cause deterioration of the output, as well as a decrease in output and fluctuations during playback.

Therefore, in the case of a metal thin film type medium or an oxide thin film type medium, it is conceivable to form a protective layer made of hard material on the recording magnetic layer to protect it. As specific examples of the protective layer, thin films of silicon oxide, aluminum oxide, titanium nitride, and the like have been proposed. However, these hard protective layers are made of brittle materials and are easily abraded by contact with the magnetic head, and the abrasion particles can damage the media and head, so they are insufficient as a solution to the above-mentioned problems. It is.

In this case, forming a thick protective layer is considered to be effective at least in preventing wear of the recording magnetic layer, but this is not preferable from the viewpoint of perpendicular magnetic recording characteristics. In other words, the perpendicular magnetic recording method essentially has a much higher recording density than the longitudinal magnetic recording method and can achieve similar recording wavelengths, but in order to do this, the effective distance between the head and the medium must be minimized. It is necessary to keep it small, and therefore the thickness of the protective layer is also limited. If the thickness of the protective layer is thus suppressed to a level that does not impair the perpendicular magnetic recording characteristics, it is difficult to expect much of an effect of improving durability.

In addition, in the case of metal thin film media and oxide thin film media, it is difficult to include lubricant in the recording layer as described above, so it is possible to apply a lubricant on the recording magnetic layer. However, since the film formed by sputtering or the like has very good surface properties, it has low lubricant wettability and lubricant retention ability, and therefore it has been difficult to uniformly apply the lubricant thereon.

[Purpose of the invention]

The purpose of this invention is to
An object of the present invention is to provide a magnetic recording medium that can significantly improve the durability of the medium itself and the magnetic head that runs in contact with the medium.

[Summary of the invention]

The magnetic recording medium according to the present invention includes silicon as a protective layer on a recording magnetic layer having perpendicular magnetic anisotropy.

Amorphous thin film containing zirconium and oxygen! (Hereinafter, 5
It is characterized by forming an i-Zr-0 amorphous thin film).

〔Effect of the invention〕

According to this invention, by forming a 5i-Zr-0 based amorphous thin film as a protective layer, it is possible to obtain a magnetic recording medium that is excellent in durability and has good perpendicular magnetic recording characteristics.

That is, since the 5i-Zr-0 amorphous thin film is very hard, it is possible to reliably protect the recording magnetic layer from damage caused by contact with the magnetic head. Moreover, 5i-
Zr-0 based amorphous thin films have superior wear resistance, that is, less brittleness, than thin films made of silicon oxide, aluminum oxide, titanium nitride, or the like. Therefore, this 5i-Zr-0
Even when a magnetic head continuously runs on an amorphous thin film, very little wear powder is generated, and wear and damage to the medium itself and the head are greatly reduced. Furthermore, since the 5i-Zr-0-based amorphous thin film is extremely dense, it has the effect of effectively shielding the recording magnetic layer from the outside air and significantly improving its corrosion resistance. Since the 5i-zr-o amorphous thin film has the above-mentioned characteristics of good wear resistance and corrosion resistance, it can improve the durability of media and magnetic heads even if the film is relatively thin. Is possible. Therefore, as mentioned above, the generation of wear particles is small, and the increase in the effective distance between the medium and the head due to wear particles is small, and the spacing loss between the medium and the head can be reduced, and the frequency characteristics can be improved. At the same time, it is possible to reduce the output drop and output fluctuation during reproduction, and to dramatically improve the perpendicular magnetic recording characteristics. That is, it is possible to provide a magnetic recording medium that satisfies both durability and perpendicular magnetic recording characteristics at the same time.

Furthermore, in addition to the above-mentioned characteristics, the 5i-Zr-0 amorphous thin film has superior lubricant wettability and lubricant retention ability compared to other conventional HIMs, so it is desirable to form a lubricant layer on top of it. By forming this, it becomes possible to further effectively reduce the friction between the medium and the head. In addition, in this case, the fact that the 5i-Zr-0 based amorphous thin film has good wettability with the lubricant layer means that the lubricant layer can be formed thin and with a uniform thickness. Comparative spacing on a magnetic recording medium with a lubricating layer formed thereon (embodiment of the invention) FIG. 1 is a sectional view showing a magnetic recording medium according to an embodiment of the invention. A recording magnetic layer is formed on both sides of this substrate 10 to a thickness of 0.5 μm by, for example, DC magneto 1 to Ron sputtering.
m Co--Cr alloy thin films 2 are formed respectively. This Co--Cr based alloy thin film 2 is oriented so as to have an axis of easy magnetization perpendicular to the film surface. That is, GO-
The Cr-based alloy thin film 2 has perpendicular magnetic anisotropy.

Then, 20% of the protective layer is formed on the C0-Cr alloy thin film 2.
A 5i-Zr-0 amorphous thin film 3 having a thickness of about 500 to 500, preferably about 50 to 400, is formed.

The 5i-Zr-0 amorphous thin film 3 is formed, for example, by high-frequency sputtering using targets of silicon nitride and zirconium oxide. The thus formed 5i-Zr-
The 0-based amorphous alloy thin film 3 has good compatibility and adhesion with the Co'Cr-based alloy thin film 2, and is extremely hard and resistant to wear.

Therefore, even when running in continuous contact with a magnetic l\rad medium like a floppy disk, extremely high durability can be obtained.

Table 1 shows the results of experiments to investigate the durability of magnetic recording media in which various protective layers were formed on Co--Cr alloy thin films by high-frequency sputtering. however,
The experiment was conducted by fabricating a magnetic recording medium with the above configuration in the form of a Nittsubee disk, and while rotating this disk at 300 revolutions per minute, a ferrite magnetic head was brought into contact with the same track on the disk. . here,
Durability is the number of passes (passes) until at least one of the media (disk) and spatula is significantly damaged. In the case of a medium, significant damage refers to a state in which at least a portion of the retention II layer and the recording magnetic layer is scratched off, exposing the surface of the substrate.

As is clear from Table 1, s +-Z based on this invention
A protective layer made of an r-0-based amorphous thin film has a thinner film thickness and significantly improved durability compared to thin films of aluminum oxide, tungsten carbide, boron nitride, titanium nitride, etc. that have been proposed as protective layers in the past. Be looked at.

Further, according to the above embodiment, the recording magnetic layer is made of especially C0-Cr.
Since the Co-Cr alloy thin film 2 has a structure in which the 3i-7r-0 amorphous thin film 3 is formed, the Cr acid component s + -zr-o in the Co-Cr alloy thin film 2 Since it contributes to improving the adhesion with the amorphous thin film 3, it is possible to improve the adhesion of the 5i-Zr-0 amorphous thin film 3 by 1q without intervening an intermediate layer. Therefore, as mentioned above, 3i-
Coupled with the fact that the 7r-0 amorphous thin film 3 itself can be thin, the effective distance between the medium and the head can be more effectively reduced, and spacing loss is extremely low even in perpendicular magnetic recording. It has the advantage of being small in size and providing good recording and reproducing characteristics.

FIG. 2 shows a magnetic recording medium according to another embodiment of the present invention, in which a base soft magnetic layer 12 is formed by vapor deposition on both sides of a non-magnetic substrate 11, and a Co--Cr based alloy is formed as a recording magnetic layer. A thin film 13 is laminated, and a 5t-Z layer is formed as a protective layer on top of the thin film 13.
An r-0 type amorphous w thin film 14 is formed by sputtering. The base soft magnetic layer 12 is, for example, a permalloy thin film,
A Co--Zr alloy thin film or a sendust alloy thin film is used.

Even in a magnetic recording medium having such a configuration, high durability such as excellent perpendicular magnetic recording characteristics can be obtained, similar to the 11K recording medium described in the above embodiment.

FIG. 3 shows a magnetic recording medium according to still another embodiment of the present invention.
A fluorocarbon-based liquid lubricant layer, for example, is applied and formed as a lubricant layer 4 on the -Zr-0-based amorphous thin film 3 .

In the magnetic recording medium of this example, especially S+-Zr
- Since the 0-based amorphous thin film 3 has excellent wettability and retention ability for the lubricant layer 4 made of a fluorocarbon-based diaphragm, the lubricant layer 4 can be formed as thin and uniformly as possible without impairing the perpendicular magnetic recording characteristics. Can be applied thickly. Also, 5i-Zr-0
A sufficient bonding force between the amorphous thin film 3 and the lubricating layer 4 can also be obtained.

Table 2 shows the results of investigating the relationship between various combinations of materials for the protective layer and lubricant layer formed on the C0-Cr alloy thin film and durability.

Table 2 As shown in Table 2, in the magnetic recording medium according to the present invention in which a fluorocarbon lubricant layer is formed on a 5i-Zr-0 amorphous thin film, the protective layer 5i-Zr-0 While keeping the amorphous thin film and lubricating layer to a thin thickness suitable for perpendicular magnetic recording, it has significantly improved durability compared to conventional magnetic recording media that use aluminum oxide or tungsten carbide films as protective layers. It is clear to show.

This invention is not limited to the embodiments described above,
Various modifications can be made without departing from the gist of the invention. For example, in the embodiment, the recording magnetic layer is made of co-Cr.
Although a Co-Cr based alloy thin film is shown as an example, films other than Co-Cr based alloy thin films may be used as long as they have perpendicular magnetic anisotropy.
Further, the material is not limited to such a metal thin film, but may also be a metal oxide thin film.

Furthermore, although the embodiments have described magnetic recording media in which a recording magnetic layer, a protective layer, and a lubricating layer are formed on both sides of a substrate, the present invention can also be applied to a medium in which these layers are formed only on one side. be able to.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a magnetic recording medium according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a magnetic recording medium according to a second embodiment of the invention, and FIG. 3 is a cross-sectional view of a magnetic recording medium according to another embodiment of the invention. FIG. 2 is a cross-sectional view of a magnetic recording medium according to an example. DESCRIPTION OF SYMBOLS 1... Resin film-like substrate, 2... C0-Cr alloy thin film (distributed magnetic layer), 3... 5i-Zr-0 based amorphous thin film, 4... Lubricating layer, 11 ...Nonmagnetic substrate, 1
2...C0-Cr alloy thin film (recording magnetic layer), 13.
...5i-Zr-0 based amorphous trade thin film.

Claims (4)

[Claims] (1) A magnetic recording medium equipped with a recording magnetic layer having perpendicular magnetic anisotropy, characterized in that an amorphous thin film containing silicon, zirconium, and oxygen is formed on the recording magnetic layer. Medium. (2) The magnetic recording medium according to claim 1, wherein the recording magnetic layer is a Co-Cr alloy thin film. (3) The magnetic recording medium according to claim 1 or 2, wherein the magnetic recording medium is a floppy disk. (4) The magnetic recording medium according to claim 1, further comprising a lubricating layer formed on the amorphous thin film containing silicon, zirconium, and oxygen.