JPH0520681A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain excellent smoothness and durability by isotropically providing clusters in dots on the surface of a protective layer. CONSTITUTION:This magnetic recording medium consists of a nonmagnetic substrate 1, a Cr base layer 2, magnetic recording layer 3, and nonmagnetic protective layer 4 laminating in this order formed on the nonmagnetic substrate 1. Nonmagnetic clusters 5 are provided in dots on the protective layer 4. As for the substrate 1, any nonmagnetic material having rigidity such as glass. Al, ceramics and the like can be used. The base layer 2 is provided to make the C-axis of a Co alloy in-plane orient. This Co alloy shows uniaxial crystalline magnetic anisotropy of the recording layer 3. The magnetic recording layer 4 consists of Co alloy such as CoNiCr, CoCrTa, CoCrPt, etc., showing uniaxial magnetic anisotropy as above mentioned. On the protective layer 4, clusters 5 in dots formed with metal, oxides or nitrides which produce three-dimensional kernels are provided. Thereby, the obtd. medium is excellent in both of electromagnetic conversion function and durability.

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 used in a magnetic disk device.

[0002]

2. Description of the Related Art In recent years, a Co alloy having uniaxial crystal magnetic anisotropy such as CoNiCr or CoCrTa has been deposited on a non-magnetic substrate via a Cr underlayer along with high density recording of a magnetic recording medium. A thin film type magnetic recording medium is used. The non-magnetic substrate is usually a glass substrate or Al.
10 ~ 20μm amorphous Ni-
A P-plated layer is used (hereinafter simply referred to as an aluminum substrate). These substrates are subjected to unevenness processing called texture in order to reduce the contact resistance between the medium surface and the magnetic head and improve the durability. The texture is formed by chemical etching (chemical corrosion) in the case of a glass substrate, and mechanically formed by lapping tape or loose abrasive grains in the case of an aluminum substrate.

[0003]

However, the texture of the aluminum substrate has good durability because the unevenness is formed at a relatively coarse pitch in the circumferential direction of the disk, but the unevenness of the unevenness is large. The smoothness is poor, and it is necessary to increase the distance between the magnetic head and the magnetic recording layer of the medium, which deteriorates the electromagnetic conversion characteristics. On the other hand, in the case of a glass substrate, it is possible to secure the smoothness by reducing the height difference of the unevenness, but there is a drawback that the unevenness is inferior because the unevenness is numerous and isotropic on the entire substrate surface. ..

The present invention has been made in view of the above problems, and an object thereof is to provide a magnetic recording medium having both excellent smoothness and durability.

[0005]

The magnetic recording medium of the present invention made in view of the above object is a magnetic recording in which a Cr underlayer, a magnetic recording layer and a C protective layer are laminated in the same order on a non-magnetic substrate. In the medium, clusters are formed isotropically on the C protective layer.

[0006]

It is known that in the initial process of thin film formation by physical vapor deposition, atoms agglomerate on the substrate to form nuclei and further grow into clusters. The clusters are close to spheres and are scattered on the surface of the C protective layer and serve as a texture. The distance between the clusters is considerably wider than the distance between adjacent convexes on the chemically etched glass substrate, and the size (height) thereof can be made considerably smaller than that of mechanically formed irregularities. Therefore, it has excellent durability and smoothness.

Further, since the clusters are formed on the C protective layer, the magnetic recording layer itself is not uneven and is smooth as compared with the case where the substrate is textured.
The gap between the magnetic head and the magnetic recording layer becomes constant,
The electrical characteristics during electromagnetic conversion are improved, the modulation is good, and there are fewer missing pulses and media nozzles.

[0008]

EXAMPLE FIG. 1 shows a partial cross-sectional view of a magnetic recording medium according to an example, in which a Cr underlayer 2,
The magnetic recording layer 3 and the non-magnetic protective layer 4 are laminated in this order, and the non-magnetic clusters 5 are scatteredly formed on the protective layer 4.

The non-magnetic substrate 1 is a glass substrate,
Any non-magnetic material having a certain degree of rigidity such as an aluminum substrate and a ceramic substrate can be used. The Cr underlayer 2 is a Co alloy (crystal structure h having the uniaxial crystal magnetic anisotropy of the magnetic recording layer 4 formed thereon).
It is formed to orient the in-plane C-axis of cp) (crystal axis showing magnetic anisotropy), and is usually formed to a thickness of about 500 to 2000 Å.

As described above, the magnetic recording layer 3 is made of CoN.
It is formed of a Co alloy exhibiting uniaxial crystal magnetic anisotropy such as iCr, CoCrTa, and CoCrPt. The magnetic recording layer is not limited to a single layer of Co alloy, but may be a multilayer of Co alloy layers and Cr layers (the uppermost layer is a Co alloy layer). The thickness of the magnetic recording layer 3 (the total thickness of the Co alloy single layer and the total thickness of the Co alloy layers if it is multiple layers) is usually 600-
It is set at 800 Å. This is because a magnetic recording medium having a Brδ of about 400 to 600 G · μ is required to secure the reproduction output and reduce noise.

A non-magnetic protective layer 5 made of a continuous carbon film is formed on the magnetic recording layer 3 to a thickness of about 200 to 400 Å. On the protective layer 4, a three-dimensionally nucleated metal or oxide, such as a nitride (for example, Sn, Cr, NiP,
Al, Ti, Au, Ag, C, SiO ₂ , TiN, Zr
The clusters 5 formed by O ₂ ) are formed in scattered dots. The cluster size (height) is 15 to 350 (
It is preferably about 250) Å. If it is less than 15Å, the action as a texture is too small and the effect of improving durability is small. On the other hand, if it exceeds 350 Å, the smoothness of the substrate will be impaired, and the glide characteristics, and thus the electromagnetic conversion characteristics with the magnetic head will deteriorate. The size and number of clusters are controlled by adjusting the substrate temperature during physical vapor deposition, vapor deposition time, sputtering output, and the like.

A lubricant coating layer 6 made of a lubricant such as fluorinated polyether is formed on the protective layer 4 having the clusters 5 scattered about 10 to 50 liters. The lubricant coating layer 6 may be formed as needed. The C underlayer, magnetic recording layer, protective layer, and cluster described above are formed by a physical vapor deposition method such as sputtering, ion beam sputtering, ion cluster beam sputtering, or vacuum vapor deposition.
It is formed.

Next, specific examples will be given. (1) The substrate in Table 1 is mirror-finished and the substrate temperature is 260 ℃, Ar
A Cr underlayer 2000Å and a magnetic recording layer (Co alloy single layer) 800Å were laminated on the substrate by sputtering at a pressure of 2.0 × 10 ^-2 (Torr). For Examples 1 and 2, the substrate was then cooled to room temperature and a C protective layer on top of 120Å.
After forming the film, the substrate temperature was set to 250 ° C. and the sputtering time was adjusted to form the Au clusters in the table. On the other hand, Example 3
5 to the conventional example, after forming the magnetic recording layer,
A g or C protective layer was formed. In Examples 3 to 5, after reheating, the sputter output was further adjusted to form C clusters in the table. Then, Examples 1 to 5 and Conventional Example 1,
In both cases, 10 liters of liquid lubricant was applied on top of it. Table 1
The roughness of the cluster, which indicates the height, is calculated from the film formation rate. Further, in the conventional example, a texture is formed on the surface of the substrate by chemical etching, and the surface roughness shows Rmax by a stylus type roughness meter.

[0014]

[Table 1]

(2) A CSS test was carried out using the above sample, and the number of CSS times until the friction coefficient exceeded 1.0 was measured. The head used for the test was a thin film microslider head (length: 0.112 inch × width: 0.015 inch, load 7.
5 grams), the disk rotation speed is 3600 rpm, and the measurement position is a radius r = 25 mm from the rotation center. Further, the glide height was measured, and the results are also shown in Table 1. (3) From the table, the glide height is almost the same as that of the second example and the conventional example 2 having the substantially same surface roughness. Markedly improved. In addition, comparing Example 5 and Conventional Example 1 in which the number of CSSs is substantially the same, in the example, the glide height is remarkably reduced, and a significant improvement in electromagnetic conversion characteristics can be expected. Also in the other examples, extremely large durability and reduction in glide height equal to or higher than the conventional one are recognized. (4) Next, using Example 1 and Conventional Example 1, the electrical characteristics were measured. The measurement conditions are as follows, and the measurement results are shown in Table 2.・ Measurement conditions Head: thin film head, gap width: 0.4 μm, track width: 13 μm, number of turns: 30 turns, number of revolutions: 3600 r
pm, position… 23.5mm from the center of rotation, frequency… 5MHz

[0016]

[Table 2]

(5) From Table 2, it is recognized that the magnetic recording layer in the example is smooth, so that the medium noise, the positive modulation and the negative modulation are small and the missing pulse is small as compared with the conventional example.

[0018]

As described above, in the magnetic recording medium of the present invention, clusters formed by agglomeration and growth of atoms are isotropically scattered on the surface of the non-magnetic protective layer, so that the height is high. Low convex areas are scattered around the medium surface, the contact area with the magnetic head can be reduced without impairing the smoothness, and excellent electromagnetic conversion performance and durability are combined. You can Further, since the magnetic recording layer itself has no irregularities and is smooth, the gap between the magnetic head and the surface of the magnetic recording layer is constant, and the electrical characteristics are superior to those of the substrate having a texture.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a magnetic recording medium of the present invention.

[Explanation of symbols]

 1 non-magnetic substrate 2 Cr underlayer 3 magnetic recording layer 4 protective layer 5 cluster

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isao Endo 1-247 Shikitsuhigashi, Naniwa-ku, Osaka City, Osaka Kubota Corporation

Claims (1)

1. A magnetic recording medium in which a Cr underlayer, a magnetic recording layer and a non-magnetic protective layer are laminated in the same order on a non-magnetic substrate. A magnetic recording medium having magnetic clusters formed in a scattered manner.