JPH05109045A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To form a medium whose coercive force is high even when an ultimate vacuum is low by a method wherein a Co-Cr-Ta-Pt alloy thin film whose composition is specific is used for a magnetic recording layer. CONSTITUTION:An alloy thin film which is composed of four elements indicated by Co(100-x-y-z)CrxTayPtz is used. In this case, (x), (y) and (z) are selected respectively in the following manner in terms of their atomic %: 3.0<=x<=17.0; 0.5<=y<=6.5; and 0<=z<=18.0. Thereby, even when the film is formed in a state that the ultimate vacuum inside a tank immediately before its film formation operation is low, a magnetic recording medium whose coercive force is high and whose S/N ratio is high can be obtained with high productivity.

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 for high density recording used for a magnetic disk used as a magnetic memory in an external storage device (magnetic disk device) such as a computer. is there.

[0002]

2. Description of the Related Art Conventionally, tapes coated with magnetic powder have been widely used as storage media for computers and the like. However, this storage tape system has drawbacks such as low storage density and long access time. For this reason, recently
Disc-shaped magnetic discs that can be randomly accessed are widely used. Among them, magnetic discs using an aluminum alloy or the like as a substrate, so-called hard discs, have come into use.

This magnetic disk is generally formed by forming a magnetic recording layer having a thickness of about 1 μm on a hard substrate having a thickness of about 2 mm, and the magnetic recording layer is generally γ.
A magnetic powder such as —Fe ₂ O ₃ mixed with a binder and applied on a disk substrate by a method such as a spin coat has been used. However, the magnetic disk obtained by this method has a limit in the magnitude of saturation magnetization, and has almost reached the limit as a high density recording medium. Therefore, in order to obtain a medium capable of higher density recording, an alloy thin film of cobalt-platinum or the like having a high coercive force or an alloy thin film of cobalt-chromium-tantalum or the like having a high SN ratio is vacuum deposited or vacuumed. What has been formed by a film forming technique on a disk substrate or an underlayer formed on the substrate is beginning to be used.

However, the magnetic recording medium using the above cobalt-platinum-based or cobalt-chromium-tantalum-based alloy thin film is required to obtain a high coercive force and a high SN ratio necessary for achieving high density recording. The ultimate vacuum in the vacuum chamber immediately before the film must be controlled to the level of 10 ⁻⁷ torr or less, and the magnetic properties are highly dependent on the ultimate vacuum, so that the productivity can be stably improved. There is a problem that it becomes difficult.

[0005]

In view of the above problems, an object of the present invention is to improve productivity such that a high coercive force and a high SN ratio can be achieved even when a film is formed in a state where the ultimate vacuum before film formation is low. An object is to provide an excellent magnetic recording medium.

[0006]

Means for Solving the Problems The present inventors have found, after intensive studies to solve the above problems, the magnetic recording layer, the following composition _{formula, Co (100-x-y} -z) Cr x Ta _y Pt _z (where x, y, and z are 3.0% x 1 in atomic%, respectively)
7.0, 0.5 ≦ y ≦ 6.5, and 0.0 <z ≦ 18.0. It was found that a magnetic recording medium having a high coercive force and excellent productivity can be obtained even if the ultimate vacuum before film formation is low by using an alloy thin film composed of four elements represented by Has been completed.

That is, the present invention provides a magnetic recording medium comprising a magnetic recording layer made of a magnetic metal thin film and a protective layer for protecting the magnetic recording layer provided on a non-magnetic substrate with a non-magnetic underlayer interposed therebetween. The present invention relates to a magnetic recording medium in which the composition of the magnetic recording layer is an alloy thin film composed of the four elements represented by the above composition.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a partial sectional view showing an embodiment of a magnetic recording medium according to the present invention. As the base body 1, a nickel-phosphorus (Ni-P) plated film, an aluminum alloy coated with an anodized alumite film, a ceramic such as a silicon nitride sintered body, an aluminum oxide sintered body, or a metal such as stainless steel or a titanium alloy is used. , Glass, plastic, etc. are used. In addition, a nonmagnetic thin film of chromium or the like is used as the underlayer 2 in an amount of 500 to 5
The film is formed to a thickness of 000 angstrom.

Cobalt-chromium-tantalum-platinum (hereinafter Co-Cr-Ta-) according to the present invention is formed on the underlayer 2.
A magnetic recording layer 3 made of a Pt) -based alloy thin film is formed. The magnetic recording layer _{Co (100-x-y-} z) Cr x T
When expressed as a _y Pt _z , x (atomic%) is 3.0 ≦ x ≦ 1.
7.0, preferably 5.0 ≦ x ≦ 15.0, y
(Atomic%) is 0.5 ≦ y ≦ 6.5, preferably 1.
0 ≦ y ≦ 5.0, and z (atomic%) is 0.0 <z ≦
18.0, preferably 4.0 ≦ z ≦ 15.0.
When the addition amount of these four elements is less than the above range,
The effect of the present invention may not be obtained, or the coercive force of the obtained medium may be deteriorated. On the other hand, when the addition amount is larger than the above range, the effect of the present invention may not be obtained or may be obtained. The coercive force and saturation magnetization of the medium may decrease. Above all, when the content of platinum is increased, the cost is remarkably increased, which is not practical.

The thickness of the magnetic recording layer is 100 to 2000 angstroms, more preferably 300 to 1500 angstroms.

A protective layer 5 made of an inorganic material such as carbon, aluminum oxide or zirconium oxide is formed on the magnetic recording layer. A suitable thickness is 50 to 400 angstroms. Further, a surface layer 4 may be added between the magnetic recording layer 3 and the protective layer 5 if necessary. This surface layer is
It is made of a thin metal film of chromium, titanium, vanadium or the like, and its thickness is preferably 50 to 200 angstrom.

In use of the magnetic recording disk obtained as described above, a liquid lubricant, a solid lubricant, or a composite lubricant of these is applied on the protective layer 5 if necessary. 6 can be formed and used.

Each of the layers 2 to 5 is formed by a vacuum film forming technique such as sputtering or vacuum evaporation, and the lubricating layer 6 can be formed by a method such as sputtering, vacuum evaporation, spin coating or dipping.

[0015]

According to the magnetic recording medium of the present invention, by using a Co-Cr-Ta-Pt alloy thin film having a specific element ratio as a magnetic recording layer, the magnetic recording medium reaches the inside of the vacuum chamber immediately before film formation. Since a magnetic recording medium having a high coercive force can be manufactured even if the degree of vacuum is low, the productivity can be remarkably improved.

[0016]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples.

Example 1 A magnetic recording medium of the present invention was manufactured as follows. An aluminum alloy coated with a nickel-phosphorus (Ni-P) plated film having an average surface roughness of 100 Å was used as a base. A chromium film having a thickness of 3000 Å was formed as an underlayer on this underlayer, and a Co—Cr—Ta—Pt alloy thin film (provided that
The content of Cr is 12 atomic%, the content of Ta is 2 atomic%,
The Pt content was 5 atomic% and the balance was Co.) 600 angstroms were continuously deposited in the same chamber by the DC sputtering method.
Furthermore, a carbon film having a thickness of 300 Å was formed as a protective layer on this layer by a DC sputtering method to manufacture a magnetic recording disk. FIG. 2 shows the change in coercive force when the ultimate vacuum in the vacuum chamber was changed immediately before the formation of the underlayer. According to FIG. 2, the coercive force is almost constant regardless of the ultimate vacuum degree.

Example 2 The ultimate vacuum was set to 5 × 10 ⁻⁷ Torr, 5 × 10 ⁻⁶ T
orr and T of the magnetic recording layer Co-Cr-Ta-Pt film
a content of 2 atomic%, Pt content of 5 atomic%, C
A magnetic disk was obtained in the same manner as in Example 2 except that the content of r was changed. Table 1 shows the dependency of the coercive force on the Cr content.

Example 3 The Cr content of the magnetic recording layer Co-Cr-Ta-Pt film was set to 1
A magnetic disk was obtained in the same manner as in Example 2 except that the content of 2 atom% and the content of Pt were 5 atom% and the content of Ta was changed. Table 2 shows the dependence of the coercive force on the Ta content.

Example 4 Example 4 except that the Cr content of the Co-Cr-Ta-Pt film of the magnetic recording layer was 12 at%, the Ta content was 2 at%, and the Pt content was changed. A magnetic disk was obtained in the same manner as in 1. Table 3 shows the Pt content dependency of the coercive force.

Comparative Example 1 A magnetic recording layer was formed of a Co--Cr--Ta alloy thin film (however, the content of Cr was 12 atomic%, the content of Ta was 2 atomic%, and the balance C was used).
A magnetic disk was manufactured in the same manner as in Example 1 except that the value was set to “o”. The relationship between the ultimate vacuum and coercive force immediately before film formation is shown in FIG. According to FIG. 3, the coercive force tends to remarkably decrease as the ultimate vacuum becomes worse.

Comparative Example 2 The same as Example 1 except that the magnetic recording layer was made of Co—Cr—Pt (however, the content of Cr was 12 at%, the content of Pt was 5 at%, and the balance was Co). A magnetic disk was manufactured by the method described above. The relationship between the ultimate vacuum and coercive force immediately before film formation is shown in FIG. According to FIG. 4, the coercive force tends to remarkably decrease as the ultimate vacuum deteriorates.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of a magnetic recording medium in Example 1.

FIG. 2 is a diagram showing the relationship between the ultimate vacuum and coercive force of a magnetic recording medium in Example 1 immediately before film formation.

FIG. 3 is a diagram showing the relationship between the ultimate vacuum and the coercive force of a magnetic recording medium immediately before film formation in Comparative Example 1.

FIG. 4 is a diagram showing the relationship between the ultimate vacuum and the coercive force of a magnetic recording medium in Comparative Example 2 immediately before film formation.

[Explanation of symbols]

 1: Underlayer 2: Underlayer 3: Magnetic recording layer 4: Surface layer 5: Protective layer 6: Lubricating layer

Claims (1)

[Claims] 1. A magnetic recording medium comprising a magnetic recording layer made of a magnetic metal thin film and a protective layer for protecting the magnetic recording layer provided on a non-magnetic substrate with a non-magnetic underlayer interposed therebetween.
Magnetic recording layer satisfies the following composition formula _{Co (100-x-y-} z) Cr x Ta y Pt z ( where, x, y and z are respectively atom% 3.0 ≦ x
≦ 17.0, 0.5 ≦ y ≦ 6.5, 0.0 <z ≦ 18.
It is 0. ) A magnetic recording medium characterized by being an alloy thin film composed of four elements represented by