JPH07161026A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide a recording medium having high coercive force by forming a film of a specified compsn. on a substrate having the surface containing oxides, and then forming a magnetic film of a Co alloy thereon. CONSTITUTION:A silicon nitride, aluminum nitride or titanium nitride film 2 is formed on a nonmagnetic substrate 1 and a magnetic recording film 3 of Co or an alloy essentially consisting of Co is formed on the film 2. Glass or glazed alumina or titania is used for the substrate 1, and subjected to surface treatment to form a fine rugged pattern to prevent sticking of a magnetic head to the substrate 1. A magnetic disk is produced by forming films on this substrate 1 by using an in-line film forming device. In this method, a silicon nitride film 2 is formed to about 30nm thickness by CVD method to prevent diffusion of oxygen from the substrate 1, and then a Co-alloy recording film 3 is formed to about 30nm thickness at 400 deg.C substrate temp. by sputtering method. Thus, higher coercive force can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium such as a magnetic disk and a magnetic tape, and more particularly to a magnetic recording medium formed on a substrate having a surface containing an oxide.

[0002]

2. Description of the Related Art In a device for processing information, such as a large computer, a personal computer, a notebook computer, etc., the portion that stores information by magnetism is called a magnetic disk device. Record and play on the disc. A magnetic disk has a structure in which a magnetic recording film is formed on a non-magnetic substrate such as a disc-shaped aluminum, glass, ceramic, silicon or titanium. Research on increasing the recording density of this magnetic recording film has been conducted. It is being actively conducted.

By the way, at present, there is a demand for miniaturization and large capacity of magnetic disks. For this reason, the requirements for the substrate are a smaller diameter and a thinner plate, and a surface smoothness in view of head flying. As substrates satisfying those requirements, glass or ceramic substrates such as alumina or zirconia have attracted attention, and the conditions under which a high performance magnetic recording film can be formed on these substrates have been studied. For example, taking an example of a magnetic recording film on an aluminum substrate (currently mainly used as a substrate), there is a texture process that is closely related to the flying of the head and a film forming process for improving the crystallinity of the film. There is a method of raising the substrate temperature. However, there is a disadvantage that nickel-phosphorus on an aluminum substrate is magnetized at a temperature of 300 ° C. or higher, and cannot be used for magnetic recording. However, when a substrate made of ceramic or the like is used, there is no problem of magnetization, and the substrate temperature at the time of forming the recording film can be increased. For example, Journal of Applied Magnetics of Japan Vol.15, No.2, p
According to 89-92, chromium is used as the base film on the glass substrate,
Cobalt-nickel-chromium alloy recording film r.
When the substrate was manufactured by the f magnetron sputtering method at a substrate temperature of 300 ° C., a coercive force (Hc) of 160 kA / m or more was obtained.

[0004]

One of the conditions for obtaining a high-performance magnetic recording film is a high coercive force. However, when forming a magnetic recording film on a substrate containing an oxide such as a ceramic substrate, oxygen contained in the substrate causes a decrease in coercive force.

(1) The magnetic recording film of the magnetic disk is formed by heating the substrate and sputtering. In the case of a substrate having a surface containing an oxide, which is taken up here, the substrate temperature is raised during the formation of the recording film, so that the diffusion of oxygen from the substrate increases and the oxygen content of the recording film increases. The increase of oxygen in the film lowers the crystallinity and lowers the coercive force.

(2) To prevent the magnetic head from sticking to the magnetic recording medium and to provide a high holding power for the magnetic recording film, a surface treatment is applied to the substrate to make fine irregularities. The formed film loses the continuity of the film on the convex portion or the concave portion. In a substrate having a surface containing an oxide from the discontinuous portion, diffusion of oxygen occurs and crystallinity is lowered,
The coercive force decreases.

An object of the present invention is to prevent oxygen from a substrate having an oxide-containing surface from diffusing into a magnetic recording film, improve the crystallinity of the recording film, and obtain a higher coercive force. Then, a better magnetic recording film and a magnetic disk device are manufactured.

[0008]

As means for solving the above problems, a film for preventing oxygen from the substrate from affecting the recording film is formed between the substrate and the base film. The reasons for selecting the oxygen prevention film are (1) the free energy of formation of the oxide is low, and the oxide is easily formed.

(2) Form a dense film.

The point is as follows. From the above, a film made of a nitride such as silicon nitride, titanium nitride, or aluminum nitride is applied to a thickness of about 10 nm to 200 nm.

[0011]

According to the present invention, oxygen from the substrate having the surface containing oxide can be prevented by the nitride film. A nitride such as silicon nitride, titanium nitride, or aluminum nitride has a low free energy of formation of an oxide and easily forms an oxide. Therefore, oxygen from the substrate forms an oxide in the nitride film and prevents diffusion into the recording film. As a result, a decrease in crystallinity of the recording film can be prevented, and a magnetic recording medium having a high coercive force can be manufactured in the magnetic recording medium having the recording film on the substrate. Further, the surface treatment on the substrate does not lose its effect due to the prevention film.

[0012]

[Practical Example] An embodiment of the present invention will be described with reference to the drawings. As an evaluation method, the magnetic characteristics of the magnetic recording medium were measured by VSM, and the components in the film were observed by Auger electron spectroscopy.

A first embodiment will be shown. FIG. 1 shows a magnetic recording medium in which silicon nitride, aluminum nitride, or titanium nitride 2 is formed on a non-magnetic substrate 1, and a magnetic recording film 3 made of cobalt or an alloy containing cobalt as a main component is formed on the film. A sectional view is shown. Here, it is used as a non-magnetic substrate 1 made of glass, glaze alumina, titania, or the like, and is subjected to surface treatment for making fine irregularities in order to prevent the magnetic head from sticking to the substrate. Film formation was carried out on this substrate using an in-line type film forming apparatus to manufacture a magnetic disk. First, a silicon nitride film 2 for preventing oxygen diffusion from the substrate according to the present invention is formed on the substrate by a CVD method to a film thickness of about 30 nm. Next, the cobalt alloy recording film 3 is formed at a substrate temperature of 400 ° C. by a sputtering method with a film thickness of about 30 nm.

[0014]

[Table 1]

The coercive force of the magnetic recording film formed as described above is improved. (See Table 1) The results measured by Auger electron spectroscopy are shown in FIGS. 3 and 4. For comparison with Example 1, FIG. 3 shows a magnetic disk in which a cobalt-chromium-tantalum alloy magnetic film having a thickness of 30 nm is formed on a substrate which has been subjected to surface treatment for making unevenness as shown in FIG. FIG. 4 is a result of observing the magnetic disk manufactured in Example 1. From FIG. 5, it can be seen that oxygen, which is considered to be contained in the substrate, is diffused into the recording film. On the other hand, in the case of FIG. 4, it was confirmed that diffusion to the nitride film was observed but not to the recording film, and the effect of the nitride film was obtained. Also, fine irregularities are observed on the surface of the magnetic recording medium. Therefore, in the magnetic recording medium having fine irregularities on the surface, by attaching the nitride film, the effect of the surface treatment applied on the substrate is not lost, and from the comparison between FIG. 3 and FIG. It is considered that the diffusion of oxygen from the discontinuous portion of the film at 4 is also suppressed.

FIG. 5 showing a second embodiment is a non-magnetic substrate 1.
A cross-sectional view of a magnetic recording medium on which a nitride film 2 having fine irregularities and then a cobalt alloy recording film 3 are formed is shown.
Here, using the same film forming apparatus as in the first embodiment, first, a silicon nitride film 2 is formed to a thickness of 200 nm on a non-magnetic substrate 1 having a smooth surface, such as glass, glaze alumina, or titania, by a CVD method. The substrate on which the nitride film is formed is applied to a texture device to form concentric grooves. At this time, it was confirmed that the concave portion of the nitride film did not reach the nonmagnetic substrate. Next, the cobalt alloy recording film 3 is applied to the substrate temperature of 400 ° C.
A film thickness of 30 nm was formed at. The magnetic disk manufactured in this manner is superior to the one without the nitride film. The results of Auger electron spectroscopy are similar to those of Example 1.

A third embodiment will be shown. The cross section of the magnetic disk used here is shown in FIG. 6, and the nitride film 2 is formed on the non-magnetic substrate 1.
Next, the structure in which the magnetic films 3 and the non-magnetic films 4 are alternately attached is shown. Specifically, a silicon nitride film 2 having a thickness of about 30 nm is formed by a CVD method on a glass or alumina ceramic substrate 1 which has been surface-treated so as to have fine irregularities similar to those used in the first embodiment. Next, the substrate temperature is 450 ° C
Then, a recording film in which a cobalt alloy recording film having a film thickness of 3 nm and a chromium film having a film thickness of 5 nm are alternately laminated in three layers is sequentially formed by a sputtering method. In this example, the film formation is performed at a higher substrate temperature than that in Example 1, and it is considered that the diffusion amount of oxygen from the substrate is increased. Is recognized, and the coercive force is improved. Further, although the recording film is a multilayer film, the influence on the crystallinity of the nitride film was small.

From the above examples, the coercive force is as shown in Table 1 when comparing the case where the silicon nitride film is formed on the substrate and the case where the silicon nitride film is not formed. The improvement was recognized.

[0019]

According to the present invention, by forming a film made of a nitride such as silicon nitride or aluminum nitride or titanium nitride on a substrate, oxygen from the substrate having a surface containing oxide can be converted into silicon or aluminum. Alternatively, by forming an oxide with titanium, it is possible to prevent diffusion into the base film or the recording film. Therefore, a higher coercive force can be obtained in a magnetic recording medium using a substrate having a surface containing an oxide.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a magnetic recording medium created in Example 1 of the present invention.

FIG. 2 is a cross-sectional view of a magnetic recording medium without a nitride film.

3 is a graph showing the results of Auger electron spectroscopy of the magnetic recording medium shown in FIG.

FIG. 4 is a graph showing the results of Auger electron spectroscopy of the magnetic recording medium shown in FIG.

FIG. 5 is a sectional view of a magnetic recording medium prepared in Example 2 of the present invention.

FIG. 6 is a sectional view of a magnetic recording medium prepared in Example 3 of the present invention.

[Explanation of symbols]

1 ... Glass substrate or glaze alumina or titania substrate, 2 ... Silicon nitride film or titanium nitride film or aluminum nitride film, 3 ... Cobalt or alloy recording film containing cobalt as a main component, 4 ... Chromium or alloy containing chromium as a main component film.

Claims (6)

[Claims] 1. A magnetic recording method comprising: forming a film made of silicon nitride, titanium nitride, or aluminum nitride on a substrate having an oxide-containing surface, and forming a magnetic film made of a cobalt alloy on the film. Medium. 2. A film made of silicon nitride, titanium nitride, or aluminum nitride is formed on a substrate having a surface containing an oxide, and a magnetic film made of a cobalt alloy and a nonmagnetic film are alternately formed on the film. A magnetic recording medium characterized by: 3. The material for forming the non-magnetic film is chromium or an alloy containing chromium as a main component, or aluminum, copper, molybdenum, tantalum or an alloy containing them as a main component. Magnetic recording medium. 4. A substrate having an oxide-containing surface is subjected to a surface treatment for forming fine irregularities, and a film made of silicon nitride, titanium nitride or aluminum nitride is formed thereon. Item 1. The magnetic recording medium according to item 1, 2 or 3. 5. A film made of silicon nitride, titanium nitride, or aluminum nitride is formed on a substrate having a surface containing an oxide, and a surface treatment for making fine irregularities on the surface is performed. Item 5. The magnetic recording medium according to any one of Items 1 to 4. 6. A magnetic disk drive using the magnetic recording medium according to claim 1.