JPS61131225A - 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 providing a protective layer of an amorphous material contg. Si and N and incorporated with O on a magnetic recording layer having magnetic anisotropy so that an infrared absorption maximum may be obtained in a region of wave length in the specified range. CONSTITUTION:A recording layer 2 is formed by a material such as a Co-Cr alloy having vertical magnetic anisotropy on a substrate 1 such as a plastic film. An Si-N-O protective film 3 of Si and N incorporated with an appropriate amt. of O wherein an infrared absorption maximum is shown in the 1/lambda range 830-1,100cm<-1>, where lambda is the wave length, is formed on the layer 2 in 20-500 Angstrom thickness by high-frequency sputtering, etc. in an atmosphere contg. gaseous oxygen with silicon nitride as the target. The film 3 is excellently adhered to the magnetic layer 2, and has high hardness and abrasion resistance. Consequently, the durability of the magnetic layer 2 and a magnetic head can be improved. Moreover, a lubricating layer of fluorocarbon, etc. can be provided thinly on the film 3 in about 30-250 Angstrom thickness to further improve the traveling performance and durability.

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 there has been an increasing demand for higher capacity magnetic recording media such as floppy disks. 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 having perpendicular magnetic anisotropy, and is a coating-type medium that constitutes most of the magnetic recording media for in-plane recording currently in practical use. Metal thin film type media in which a metal thin film such as a co-Cr alloy is formed as a recording magnetic layer by sputtering or vapor deposition, or oxide thin film type media having a magnetoplumbite crystal structure such as 3a ferrite or Sr ferrite 1~. The medium is seen as promising as a medium more suitable for high-density recording.

By the way, in coated media, the recording magnetic layer is formed by mixing magnetic powder with a binder or the like and coating it on the substrate, so the recording magnetic layer has elasticity, and a lubricant is added to the magnetic layer. It is also possible to mix it in, thereby maintaining good contact between the medium and the magnetic head and 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 layer made of hard material such as ferrite runs over the media, the media surface and head may be damaged. Damage such as scratches is likely to occur on the surface. 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, and 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 a hard material on the recording magnetic layer to protect it. A specific example of the protective layer is silicon oxide.

Thin films such as aluminum oxide and titanium nitride have been proposed in the past. However, these hard protective layers are made of brittle materials and are prone to abrasion due to contact with the magnetic head, and the abrasion particles can damage the medium and head. That is not enough. 1. 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, perpendicular magnetic recording essentially has a much higher recording density than longitudinal magnetic recording and can shorten the recording wavelength, but in order to do this, the effective distance between the head and the medium must be kept extremely small. 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.

[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) A magnetic recording medium according to the present invention includes silicon and nitrogen as a protective layer on a recording magnetic layer having perpendicular magnetic anisotropy, and has a wavelength of 1/λ (wave number), where λ is a wavelength of λ. 830
A thin film containing oxygen (hereinafter referred to as 5i-N-0 N film) is formed as a protective layer so as to exhibit maximum absorption of infrared rays in the range exceeding cm-' and less than 1100 cn-". There is.

〔Effect of the invention〕

According to this invention, by forming a 5i-N-0 thin film containing an appropriate amount of oxygen as a protective layer, a magnetic recording medium with excellent durability and good perpendicular magnetic recording characteristics can be obtained.

In other words, such a 5i-N-0 thin film containing an appropriate amount of oxygen has a Gockers hardness of approximately 1300 to 9/rd, and is extremely hard, so it is extremely hard to prevent the recording magnetic layer from being damaged by contact with the magnetic head. It is possible to protect against

Furthermore, this 5i-N-0 type thin film has superior wear resistance compared to thin films made of silicon oxide, aluminum oxide, titanium nitride, or the like.

Therefore, even if the magnetic head continuously runs on this S 1-N-0 thin film, very little abrasion powder is generated, and wear and damage to the medium itself and the head are greatly reduced. Furthermore, since this Si-N-0 thin film is extremely dense as a material, it has the effect of effectively shielding the recording magnetic layer from the outside air and significantly improving corrosion resistance. This effect is especially true in 3i above.
This is more noticeable when the -N-0 thin film is amorphous. This 5i-N□O thin film also has the above-mentioned characteristics of good wear resistance and corrosion resistance, so even if the film is relatively thin, it can improve the durability of media and magnetic heads. be. 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.

(Embodiment of the Invention) FIG. 1 is a sectional view showing a magnetic recording medium according to an embodiment of the invention. In the figure, the substrate 1 is a film-like substrate made of resin, and a recording magnetic layer is formed on both sides of the substrate 1 by, for example, direct current magnetron sputtering to a thickness of 0.5 μm.
Co--Cr based alloy thin films 2 are formed respectively.

This Co--Cr alloy thin film 1] 12 is oriented so as to have an axis of easy magnetization perpendicular to the film surface. That is, c
The o-Cr alloy thin film 2 has perpendicular magnetic anisotropy.

Then, on the Co-Cr base metal thin film 2, a protective layer of 20
A 5i-N-0 optical thin film 3 containing an appropriate amount of oxygen and having a thickness of 500 to 500, preferably 50 to 400, is formed respectively.

The 5i-N-O optical thin film 3 is formed, for example, by high frequency sputtering using a silicon nitride target. In this case, the sputtering vacuum chamber was previously evacuated to about 10-' Torr, residual impurity gas was sufficiently removed, and then argon gas and oxygen gas were introduced to about 10-' Torr to perform sputtering. In addition, S+-N-O type thin 1!
In addition, reactive sputtering using a silicon target can also be used to form I3. This 5i
The proportions of silicon, nitrogen, @ element, and other impurities in the -N-0 thin film 3 are controlled by the film formation rate, the oxygen partial pressure of the sputtering gas pressure, and the like. S i thus formed
-N-0 thin film 3 is generally amorphous, and Co-Cr
It has good compatibility and adhesion with the alloy thin film 2, and is very hard and hard to wear. Therefore, extremely high durability can be obtained even when the magnetic head runs in continuous contact with the medium as in the case of a floppy disk.

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,
A magnetic recording medium having the above-mentioned configuration was prepared in the form of a floppy disk, and the disk was rotated at 300 revolutions per minute while 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 medium (disc) and the spatula is significantly damaged. In the case of a medium, significant damage refers to a state in which at least a portion of the protective layer and recording layer is scratched off, exposing the surface of the substrate.

In addition, in Table 1, Examples 1 to 6 and Comparative Example 1.2 all use 5i-N-0 thin films as protective layers, but the durability was investigated for films with various infrared absorption maximum regions. Ta. In addition, Thin II! The ratio of silicon, nitrogen, and oxygen in No. 3 was determined by forming an oxygen-containing silicon nitride thin film on a co-Cr alloy thin film and at the same time forming it on a silicon wafer under the same conditions. Determined by Auger electron analysis.

110- As is clear from Table 1, silicon 3 based on this invention
i, 1/λ exceeds 830 cm-' for nitrogen N and 11
A protective layer made of a Si-N-0 thin film containing oxygen O so as to exhibit an absorption maximum of infrared rays in a range of less than 00 cm", especially a protective layer with 1/λ of 800 c"1 or more, 10
A magnetic recording medium in which a protective layer containing oxygen O is formed so as to exhibit maximum absorption of infrared rays in the range of 00 cm" or less,
Silicon nitride and aluminum oxide have excellent durability and have been proposed as protective layers.

Compared to thin films of tungsten carbide, boron nitride, titanium nitride, etc., the film has significantly improved durability despite being thinner. Note that the Si-N-0 thin film is made of silicon,
Needless to say, it may contain incidental impurities in addition to nitrogen and oxygen.

Further, according to the above embodiment, the recording magnetic layer is made of especially C0-Cr.
1CO-Or
Since the Or acid component in the 5i-N-O based alloy thin film 2 contributes to improving the adhesion with the 5i-N-O optical thin film 3, favorable adhesion of the 5i-N-0 based thin film 3 can be obtained without intervening an intermediate layer. be able to. Therefore, as mentioned above, in combination with the fact that the 5i-N-O optical thin film 3 itself can be thin, the effective distance between the media heads can be more effectively reduced, and even in perpendicular magnetic recording, the spacing can be reduced. - It has the advantage that loss is very small and good recording and reproducing characteristics can be obtained.

FIG. 2 shows a magnetic recording medium according to another embodiment of the present invention, in which a base soft magnetic layer 1 is formed by vapor deposition on a nonmagnetic substrate 11.
2 and a GO--Cr based alloy thin film 13 as a recording magnetic layer are laminated, and an S 1-N-0 based thin film 14 is formed thereon by sputtering as a protective layer. For the base soft magnetic layer 12, a permalloy thin film, a Co--Zr alloy thin film, a sendust alloy thin film, or the like is used, for example.

A magnetic recording medium having such a structure also has excellent perpendicular magnetic recording characteristics and high durability, similar to the magnetic 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 liquid lubricant layer, for example, is applied and formed as a lubricant layer 4 on the 1-N-0 thin film 3 .

In the magnetic recording medium of this example, especially 5i-N-
Since the 0-based amorphous thin film 3 has excellent wettability and retention ability for the lubricating layer 4 made of 70% carbon-based lubricant, the lubricating layer 4
can be applied thinly and uniformly to the extent that the perpendicular magnetic recording characteristics are not impaired. Further, a sufficient bonding force between the 5i-N-0 optical thin film 3 and the lubricating layer 4 can 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 co-Cr alloy thin film and durability.

In the magnetic recording medium based on the present invention, in which a 70-hole carbon-based lubricating layer is formed as a lubricating layer on a Si-N-0-based thin film, the 5i-N-0-based thin film as a protective layer and the lubricating layer are perpendicularly magnetic. Conventional magnetic recording media that use an aluminum oxide film, tungsten carbide film, etc. as a protective layer while maintaining a thin thickness suitable for recording (Comparative Examples 3 to 9), or 5t-N-0 where the amount of oxygen is not appropriate It is clear that the durability is significantly improved compared to the medium in which a lubricating layer is formed on the thin film of the system (Comparative Example 1.2).

This invention is not limited to the embodiments described above,
Various modifications can be made without departing from the spirit of the invention. For example, in the embodiment, the recording magnetic layer is made of C0-Cr.
Although the C0-Cr alloy thin film is shown as an example, any film other than the C0-Cr alloy thin film may be used as long as it has 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 sectional view of a magnetic recording medium according to one embodiment of the invention, FIG. 2 is a sectional view of a magnetic recording medium according to another embodiment of the invention, and FIG. 3 is a further 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... Co-Cr alloy thin film (recording magnetic layer), 3... Si-N-0 based thin film, 4... Lubricating layer, 11... Non-magnetic substrate, 12.
...c. -Cr-based alloy thin film (recording magnetic layer), 13...5t-N
-0 series thin film. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2 Figure 3

Claims (6)

[Claims] (1) In a magnetic recording medium equipped with a recording magnetic layer having perpendicular magnetic anisotropy, the recording magnetic layer contains silicon and nitrogen, and where λ is the wavelength, 1/λ is 830c.
A magnetic recording medium characterized in that a thin film containing oxygen is formed so as to exhibit maximum absorption of infrared rays in a range exceeding m^-^1 and less than 1100 cm^-^1. (2) The magnetic recording medium according to claim 1, wherein the thin film is amorphous. (3) The thin film has a 1/λ of 850 cm^-^1 or more 10
3. The magnetic recording medium according to claim 1, wherein the magnetic recording medium contains oxygen so as to exhibit maximum absorption of infrared rays in a range of 50 cm^-^1 or less. (4) The magnetic recording medium according to claim 1, wherein the recording magnetic layer is a Co-Cr alloy thin film. (5) The magnetic recording medium according to claim 1, wherein the magnetic recording medium is a floppy disk. (6) The magnetic recording medium according to claim 1, further comprising a lubricating layer formed on the thin film.