JPH07118418B2 - Magnetic recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to longitudinal thin film media for hard magnetic disks.

[0002]

2. Description of the Related Art As a high density recording medium for a hard magnetic disk, a metal thin film medium by a sputtering method is now predominant instead of a coating medium. Since this thin film medium realizes high density recording, it has high output, high recording density characteristics and high S
/ N, etc. are required, the coercive force is high due to the magnetic characteristics of the medium, and the squareness ratio of the coercive force must be small.

Therefore, in order to obtain a high coercive force, NiP / Al having a texture groove in the disk circumferential direction as a substrate is used.
A Cr film is formed as a base film using a substrate, and then a CoNiCr film, a CoCrTa film, and a CoCrH film are formed as magnetic films.
A magnetic recording medium having an f film or the like has been proposed. IEICE Technical Report, CPM 88-91 and CP
M88-92, 1988 and JP-A-2-103716.
See Japanese Unexamined Patent Publication No. Hei 2-162527 and Japanese Unexamined Patent Publication No. 4-21921.

In order to reduce the squareness ratio of coercive force,
Increasing the thickness of the Cr underlayer in CoNiCr / Cr media (IEEE Transactions on Magnetics (IEEE Transactions)
non Magnetics) (Vol. 24, p2)
727-2729, 1988), CoPtCr / Cr
Producing with high Ar gas pressure in medium (IEET
transactions on MagneticsV
ol. 26, pp. 1578-1580, 1990) and so on.

[0005]

The coercive force of the medium and the squareness ratio of the coercive force are at a good level in the above-mentioned conventional thin film medium manufacturing technique by the sputtering method, but it is improved due to the reality of ultra-high recording density. There is a need to.

It is an object of the present invention to provide a magnetic recording medium in which the coercive force of the medium is increased and the squareness ratio of the coercive force is reduced in order to realize an ultrahigh recording density.

[0007]

A magnetic recording medium according to the present invention comprises a Cr undercoat film and a Co-based alloy film magnetic film on a substrate, wherein the magnetic film is a CoCrTa-based alloy film to which Hf is added. Is characterized by.

[0008]

According to the present invention, Hf is formed on the CoCrTa alloy film.
Is added to obtain a magnetic recording medium having a high coercive force and a small squareness ratio of the coercive force.

[0009]

EXAMPLES Examples of the present invention will be described below.
The film formation of the magnetic recording medium of this example was performed by an RF magnetron type sputtering device. The target is a 3N Cr target for the base film and CoCrT for the magnetic film.
A composite target was used in which Hf pellets were placed on a (12 _at % Cr, 2 _at % Ta) alloy target. Also,
As the substrate, a NiP / Al substrate with a texture groove (surface roughness R ^max = 400 Å (A)) was used.

First, Table 1 shows the sputtering conditions of this embodiment. Here, the amount of Hf added in the magnetic film was changed depending on the number of Hf pellets placed on the CoCrTa alloy target.

The magnetic characteristics of the CoCrTaHf / Cr media thus prepared with various amounts of Hf added were measured by VSM. The result is shown in FIG. FIG. 1 is a diagram showing the dependency of coercive force (Hc) and squareness ratio (S ^* ) on the amount of Hf added. The amount of Hf added was analyzed by EPMA. As shown in FIG. 1, the Hf-added medium of the present invention (however, the amount of Hf added is 1 at% or more and 9 at% or less) has a coercive force Hc improved by up to about 2000 e and a rectangular coercive force as compared with the conventional medium without Hf addition. It was also found that the ratio S ^* was reduced by about 0.1 to 0.3.

Next, the recording / reproducing characteristics of the magnetic recording medium of the present invention will be described. The medium of the present invention (No. 2 in Table 2) is H
The amount of f added was 5 at%, and a conventional medium without addition of Hf (No. 1 in Table 2) was also prepared for comparison. Incidentally, in these recording / reproducing media, 300 A thick carbon was deposited as a protective film after depositing CoCrTaHf.

Table 2 shows the evaluation results of the magnetic characteristics and the recording / reproducing characteristics. From these facts, the medium of the present invention has a higher coercive force due to the magnetic characteristics and a smaller squareness ratio of the coercive force than the conventional medium, as described above. Recording density (D) and S / N were improved. Further, the medium noise (N) was also reduced.

In addition to the above, the same effect was obtained as a result of carrying out the case of using a CoCrTaPt magnetic film as the CoCrTa-based magnetic film and adding Hf.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

The Hf-added medium of the present invention has the following effects.

(1) In the CoCrTa-based magnetic film of the present invention, 1
By adding ~ 9 at% of Hf, the coercive force can be increased and the squareness ratio of the coercive force can be reduced as compared with the conventional medium.

(2) The reproduction output, recording density, S / N and medium noise of the medium of the present invention are improved as compared with the conventional medium.

[Brief description of drawings]

FIG. 1 is a diagram showing the dependency of coercive force (Hc) and squareness ratio (S *) on the amount of Hf added to a CoCrTa film in magnetic characteristics.

Claims (2)

[Claims] 1. A thin film medium comprising a Cr undercoat film and a Co-based alloy film magnetic film on a substrate, wherein the magnetic film is Co.
A magnetic recording medium comprising Hf added to a CrTa-based alloy film. 2. The magnetic recording medium according to claim 1, wherein the added amount of Hf is 1 at% or more and 9 at or less.