JPH065574B2 - Magnetic recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium having a zirconium oxide thin film and a lubricating layer on a metal thin film constituting a recording magnetic layer.

[Technical background of the invention and its problems]

In recent years, the amount of information carried by a memory device has dramatically increased with the development of information processing technology, and the demand for larger capacity of magnetic recording media such as floppy disks has been increasing. In order to meet this demand, research and development of magnetic recording media capable of high-density recording have been actively conducted. In particular, a metal thin film magnetic recording medium formed by sputtering or vapor deposition of a metal magnetic thin film such as Co-Cr as a recording magnetic layer is promising as a medium suitable for high-density recording, as compared with the coating type magnetic recording medium currently generally used. Is being watched.

By the way, in the coating type medium, since the recording magnetic layer is formed by mixing the magnetic powder with the binder or the like and coating the mixture on the substrate, it is easy to mix the lubricant into the magnetic layer.
Thereby, the lubricity between the medium and the magnetic head can be maintained, and the durability of the medium and the head can be sufficiently obtained.

On the other hand, in a metal thin film medium, it is difficult to mix a lubricant into the recording magnetic layer. Therefore, when a magnetic head made of hard material such as ferrite travels on the medium, scratches or the like are generated on the medium surface or the surface of the head. Is easily damaged.
In this case, not only the durability of the medium and the head is impaired, but also the medium and the head wear due to the adhesion of abrasion powder.
The distance between the heads increases, the spacing loss increases, and the recording / reproducing frequency characteristics deteriorate significantly.

Therefore, in the case of a metal thin film medium, it is conceivable to form a lubricating layer by applying a lubricant on the recording magnetic layer, but the film formed by spattering or the like has a very good surface property, so The wettability of the agent is poor, and therefore it is difficult to apply the lubricant on the agent with sufficient adhesion and evenly, and the above-mentioned problems are still unsolved.

[Object of the Invention]

The object of the present invention is to make it possible to form a lubricating layer uniformly with a sufficient adhesive force even when the recording magnetic layer is formed of a metal thin film, and to significantly improve the durability of the medium itself and the magnetic head. The purpose of the present invention is to provide a magnetic recording medium having excellent recording and reproducing characteristics.

[Outline of Invention]

The magnetic recording medium according to the present invention is a magnetic recording medium in which a zirconium oxide thin film is formed on a metal thin film forming a recording magnetic layer, and a lubricating layer is formed on the zirconium oxide thin film. It is characterized in that the number of constituent oxygen atoms is less than twice the number of zirconium atoms.

That is, it is known to form a zirconium oxide thin film on a metal thin film that constitutes a recording magnetic layer, and it is also known to form a lubricating layer. By doing
This is to facilitate the application of the lubricating layer. A zirconium oxide thin film in which such oxygen deficiency occurs, that is, the number of oxygen atoms is less than twice the number of zirconium atoms,
For example, it can be easily formed by a method such as spattering in an oxygen-deficient atmosphere.

The degree of oxygen deficiency of the zirconium oxide thin film is not particularly limited, but when the composition formula of the zirconium oxide thin film is ZrO _2-X , it is desirable that X be within the range of 0 <X <0.5. When the zirconium oxide thin film is in an oxygen-deficient state such that X is within this range, the zirconium oxide thin film itself can sufficiently maintain its hardness, and the binding force with the lubricating layer can be enhanced very effectively. Here, the lubricant forming the lubricating layer is preferably a lubricant having a polar group that is bonded to a free bond generated by oxygen vacancies in the zirconium oxide thin film, and for example, a perfluoropolyether lubricant or the like is used.

〔The invention's effect〕

According to this invention, since the lubricating layer is formed through the zirconium oxide thin film in which oxygen deficiency occurs,
Provided is a magnetic recording medium in which a lubricating layer is formed well and uniformly. This is because when an oxygen deficiency occurs in a zirconium oxide thin film, an arc electron pair is generated in an oxygen atom and is activated as compared with a zirconium oxide thin film having no oxygen deficiency, and a zirconium oxide thin film and a lubricating layer formed thereon are This is because the binding force of is strengthened.

Therefore, according to the present invention, even in a magnetic recording medium in which a metal thin film such as a Co-Cr alloy thin film is used as a recording magnetic layer, lubrication between the medium and the magnetic head is sufficiently performed. Wear and damage are significantly reduced, and durability is greatly improved.

When applying a liquid lubricant, for example, as the lubricating layer,
Since the zirconium oxide thin film and the lubricant have good wettability and the lubricant can be applied to a uniform thickness, spacing loss is reduced and output drop and output fluctuation during signal reproduction are reduced, resulting in an error rate. Also decreases. Therefore, the recording / reproducing characteristics are improved.

Furthermore, since the zirconium oxide thin film is a harder material than a magnetic metal film such as a Co-Cr alloy film that forms a recording magnetic layer, it not only mechanically protects the medium surface and makes it difficult for scratches and the like to enter, It goes without saying that the corrosion resistance is also improved by shielding the recording magnetic layer from the outside air.

Example of Invention

FIG. 1 is a sectional view showing a magnetic recording medium according to an embodiment of the present invention. In the figure, a substrate 1 is a resin film-shaped substrate, and a recording magnetic layer is formed on the substrate 1 by, for example, DC magnetron buttering and Co-Cr having a thickness of 0.5 μm.
The alloy thin film 2 is formed. In the case of a perpendicular magnetic recording medium, this Co—Cr alloy thin film 2 is oriented so as to have an easy axis of magnetization in a direction perpendicular to the film surface. Then, a zirconium oxide thin film 3 having a thickness of about 200Å is formed on the Co—Cr alloy thin film 2, and a liquid lubricating layer 4 is applied and formed on the zirconium oxide thin film 3.

The zirconium oxide thin film 3 is formed by high frequency sputtering using a zirconium oxide target, for example. In this case, pulling the vacuum of the vacuum chamber for sputter to advance 10 about ^-7 Torr, after removal of the impurity gas sufficiently, the oxygen gas in the formation of more fewer the conventional zirconium oxide (ZrO _2), i.e. 10 ^-7 It was introduced up to about 10 ^-2 Torr, and then argon gas was introduced to adjust the total pressure to about 10 ^-2 Torr. The zirconium oxide thin film 3 thus formed is in an oxygen-deficient state, and its composition formula is ZrO _{2 -X} .
In this case, the value of X can be arbitrarily controlled within a range larger than 0 depending on the oxygen partial pressure of the sputtering atmosphere and the film formation rate. The value of X can be measured, for example, by (100) Si
It can be performed by forming ZrO _{2-X of} about 0.3 μm on the wafer and analyzing it by RBS (Raza-Forward Back-Skitting).

Since the zirconium oxide thin film 3 thus formed is activated by an oxygen deficiency state, when the liquid lubricant is applied on the zirconium oxide thin film 3 to form the lubricating layer 4, the wettability of the lubricant should be good and the application should be uniform. You can Further, the binding force between the zirconium oxide thin film 3 and the lubricating layer 4 also becomes strong. Therefore, the durability of the magnetic recording medium and the magnetic head can be greatly improved.

Table 1 shows the experimental results of examining the change in durability when the value of X was changed depending on the oxygen partial pressure ratio of the sputtering atmosphere and the film formation rate. However, in the experiment, the magnetic recording medium having the above-described structure was prepared in the form of a floppy disk, and the ferrite magnetic head was brought into contact with the same track on the disk while the disk was rotated at 300 rpm. . Here, the durability is the number of running times (bus) until at least one of the medium (disk) and the head is significantly damaged. In the case of a medium, the term “significant damage” means that at least a part of the zirconium oxide thin film 3 and the Co—Cr alloy thin film 2 is displaced and the surface of the substrate 1 is exposed.

From the above results, it is understood that when the value of X is larger than zero, that is, when the number of oxygen atoms forming the zirconium oxide thin film 3 is less than twice the number of zirconium atoms, the durability is significantly improved. In particular, it is preferable that the value of X is within the range of 0.1 <X <0.3. When the value of X is within this range, the durability is more than the pass and is improved by one digit or more as compared with the case where X is not more than zero. You get a value that exceeds the path. The required degree of durability varies depending on the application, etc., but if it is 500,000 passes or more, it can be practically practically used. Therefore, it is particularly desirable that the value of X is in the range of 0.1 <X <0.3 described above.

When the value of X exceeds 0.5, the durability decreases from the peak because the adhesion of the lubricating layer 4 improves in the oxygen deficient state, but the hardness of the zirconium oxide thin film 3 itself decreases. Because. However, the fact that the durability is lower than that when X is zero is very large, as is complicated by the above experimental results. For example, when the value is close to 2, the zirconium oxide thin film 3 becomes less than zirconium oxide. Since the property is lost and it becomes close to zirconium, the name itself of the zirconium oxide thin film cannot be established in that state.

Thus, according to the present invention, the zirconium oxide thin film is made to be in an oxygen-deficient state by making the number of oxygen atoms less than twice that of zirconium, thereby increasing the adhesive force of the lubricating layer formed thereon, The durability of the magnetic recording medium itself and the magnetic head can be remarkably enhanced, and the uniform formation of the lubricating layer can reduce the reduction and fluctuation of the signal reproduction output and reduce the error rate.

FIG. 3 shows a magnetic recording medium according to another embodiment of the present invention, in which a Co—Cr alloy thin film 12 as a recording magnetic layer is formed on a non-magnetic substrate 11 by a vapor deposition method, and a zirconium oxide thin film is formed thereon. 13 is formed by magnetron sputtering, for example, and a solid lubricating layer 14 is further formed thereon by sputtering. The zirconium oxide thin film 13 is also in a state of oxygen deficiency by being sputtered in an argon atmosphere having an oxygen partial pressure of about 10% of the argon partial pressure.

Also in the magnetic recording medium thus formed, excellent durability can be obtained as in the magnetic recording medium described in the above-mentioned embodiment.

The present invention is not limited to the above embodiment,
Various modifications can be made without departing from the spirit of the invention. For example, a Co-Cr alloy thin film has been illustrated as the recording magnetic layer, but a Co-Cr-Ni alloy thin film or the like may be used. In particular, the present invention uses a metal layer film for which a lubricating layer needs to be formed on the surface as the recording magnetic layer. It is effective for magnetic recording media. Further, various materials can be selected for the substrate and the lubricating layer. further,
The present invention can be applied not only to the perpendicular magnetic recording medium but also to the in-plane magnetic recording medium.

[Brief description of drawings]

FIG. 1 is a sectional view of a magnetic recording medium according to an embodiment of the present invention, and FIG. 2 is a sectional view of a magnetic recording medium according to another embodiment of the present invention. 1 ... Resin filter substrate 2 ... Co-Cr alloy thin film (recording magnetic layer) 3 ... Zirconium oxide thin film 4 ... Liquid lubricating layer 11 ... Non-magnetic substrate 12 ... Co-Cr alloy thin film (recording magnetic layer) 13 ... Zirconium oxide Thin film 14 ... Solid lubrication layer

Claims (3)

[Claims] 1. A magnetic recording medium in which a zirconium oxide thin film is formed on a metal thin film forming a recording magnetic layer, and a lubricating layer is formed on the zirconium oxide thin film, and the number of oxygen atoms forming the zirconium oxide thin film. Is less than twice the number of zirconium atoms, a magnetic recording medium. 2. The composition formula of the zirconium oxide thin film is Zr.
The magnetic recording medium according to claim 1, wherein X is selected within the range of 0 <X <0.5 when O _2−X . 3. The thin metal film forming the recording magnetic layer is Co.
The magnetic recording medium according to claim 1, which is a -Cr alloy thin film.