JPH02297713A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain an intrasurface recording-type magnetic recording medium with improved coercive force by adding at least P in a Cr film during the process of continuous formation of Cr film and Co-alloy film on a nonmagnetic substrate. CONSTITUTION:The Cr film as a base layer is formed on a nonmagnetic substrate, on which the Co-alloy film and a C film are formed. At least phospher is incorporated into the Cr base film to cause intergranular segregation of P in Cr grains, since P hardly forms solid solution in Cr. This prevents Cr grains from coarsening and promotes isolation of the grains from one another. Thereby, grains in the Co-alloy film formed on the Cr film are also isolated, which improves the coercive force of the medium compared to a conventional one which has a base layer of a Cr-alone film without addition of P.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an in-plane recording type magnetic recording medium having a high coercive force.

(Prior art) A Cr film is formed on a non-magnetic substrate made of, for example, an aluminum material by vapor deposition or sputtering, and then a Cr film is deposited on the Cr film.
Magnetic recording bodies formed with o alloy films are known. Since this magnetic recording medium has a high coercive force in the in-plane direction, it is often used as a hard disk medium capable of high-density recording.

The mechanism by which the coercive force of this magnetic recording medium is generated is as follows. That is, when a Cr film is formed on a non-magnetic substrate by a vapor deposition method or a sputtering method, a columnar particle film whose crystals are oriented so that the (110) plane of the BCC is parallel to the substrate surface is obtained. When a Co alloy film is continuously formed on the Cr film, the interatomic distance of the C axis of the HCP of the Co alloy film and the (
Since the interatomic distances in the 110) plane are almost equal, the Co alloy film grows epitaxially so that the C axis is parallel to the substrate surface. Since the C-axis of the HCP of this Co alloy film is an axis of easy magnetization, the Co alloy film becomes an in-plane magnetized film.

Furthermore, since the underlying Cr film has a relatively clear columnar grain structure, the Co alloy film grown on the Cr film also has a grain structure that is isolated from each other. As a result of the single-domain grain structure having in-plane magnetocrystalline anisotropy, a high coercive force is generated.

If there is no underlying Cr film, or if the surface of the Cr film is contaminated and epitaxial growth is not possible, the Co alloy film will have a crystal orientation with the C axis perpendicular to the substrate surface. A so-called perpendicular magnetization film corresponds to such a case.

As described above, in this type of in-plane recording type magnetic recording medium, the underlying Cr film controls the crystal direction and grain shape of the 00 alloy film, and plays an extremely important role in generating high coercive force. There is.

As the 00 alloy film, for example, Co-old, Co-N
i-Cr, Co-N1-Pt, Co-Cr, Co
-Cr-Pt, C.

-Nl -Zr, Co -Nl -W, Co -
Alloy films such as Or-Ta are known.

(Problems to be Solved by the Invention) However, in order to increase recording density, even higher coercive force is required.

A further object of the present invention is to provide a longitudinal recording type magnetic recording medium with improved coercive force.

(Means for solving the problem) In generating the coercive force of a magnetic recording medium, the underlying Cr film plays an important role in the following two ways. One of these is the Co alloy formed on the Cr film. One is to control the crystal orientation of the film, and the other is to make the Co alloy film have a film structure in the form of aggregates of particles.

Therefore, the present inventors focused on the latter effect of the underlying Cr film, and made various attempts to refine the crystal grains of the underlying Cr film. ．． : It has been found that by adding Cr, the crystal grains of the Cr film become finer, the columnar grain structure becomes clearer, and a higher coercive force can be obtained.

The magnetic recording body of the present invention was made based on the above-mentioned knowledge, and is a longitudinal recording type magnetic recording body formed by continuously forming a Cr film and a Co alloy film on a non-magnetic substrate.
The present invention is characterized in that at least P is added to the Cr film.

P to be added to Cr may be added alone, but like P, it may be added in solid solution to Cr or together with elements that are difficult to dissolve in solid form, such as Sl, rare earth elements, Cu, etc.

For example, if P, St, a rare earth element, Cu, etc. are added to Cr, the coercive force is further improved compared to when P is added alone.

(Function) By adding at least P to the underlying Cr film, P is difficult to form a solid solution in Cr, so it segregates at the grain boundaries of Cr crystal grains, causing the Cr crystal grains to become coarse. or promote separation between particles.

(Example) Next, the invention will be explained with reference to examples.

Experimental Example 1 In this experimental example, P was added as an additive to the underlying Cr film, and p-st was used with a composition ratio of P and Sl of 1:1.
Using the mixture, a Cr film and a 00 alloy film were successively formed on a nonmagnetic substrate as follows.

First, a film material in which the amount of P added to Cr was 1% was prepared as a Cr film material serving as a base.

Next, the non-magnetic substrate on which N1-P was electrolessly plated on an aluminum plate was placed in a batch type sputtering device equipped with three DC magnetron cathodes with a wide diameter, and the processing chamber of the sputtering device was vacuumed. Vacuum level l via pump
The temperature was set to below Xl0-6 Torr, and then argon gas was introduced so that the inside of the processing chamber became 2X10-'Torr. .

Next, the substrate was heated and maintained at a temperature of 200°C, and then -3
Cr having the above composition was deposited on the substrate to a thickness of 500 mm by direct current magnetron sputtering while applying a bias voltage of 0.0 V.
A Co film is formed on the Cr film to a thickness of 500 μm.
After forming a Co alloy film having a composition of 20 at % Nl - 10 at % Cr, a magnetic recording body was prepared by forming a C protective film with a thickness of 300 nm on the Go alloy film.

In addition, instead of the Cr film material containing 1% P as the underlying Cr film material, Cr film materials in which the amount of P added to Cr is 3% or 5%,
The amount of P-Sl mixture added to Cr was 0.5%, 1%, 3
% and 5%, and a Cr film material in which no P or p-st mixture was added to Cr was used, but magnetic recording bodies were prepared in the same manner as described above.

The amount of the additive added to the underlying Cr film layer formed on the substrate is adjusted by changing the area of the pellet of the additive placed on the leaf target, and the amount of the additive added to the underlying Cr film layer formed on the substrate is adjusted by changing the area of the pellet of the additive placed on the leaf target. The Co alloy film is coated with N1 and C on a Co-20at% NIGT target (product name, manufactured by Japan Vacuum Technology Co., Ltd.).
Place r pellet and reduce co-20at% old-10at%
It was adjusted to have a Cr composition.

Then, the coercive force of each of the obtained magnetic recording bodies was measured. The obtained n1 constant results are shown in FIG.

Further, the coercive force (Oe) of the magnetic recording body was 1300 when the underlying Cr film was an additive-free Cr film.

The additives in the Cr film were analyzed by Auger analysis, and the coercive force was measured by a vibrating magnetometer (vSM).
Established.

As shown in Figure 1, the base C formed on the non-magnetic substrate
It was confirmed that by adding at least P to the r film, the coercive force was improved compared to the case where no addition was made.

It was also confirmed that by adding both P and 81 to Cr, the coercive force was further improved than when P was added alone.

A cross-section of a magnetic recording body prepared by forming a Cr film containing lat% P on a non-magnetic substrate and forming the 00 alloy film and C film on the Cr film was observed by SEX. The columnar grain structure of the Cr film is clearer than that of a magnetic recording body made by forming the Co alloy film and the C film on the Cr film with a Cr film alone to which no P is added as the base. It was confirmed that the particles were also made finer.

In the above experimental example, additives were added to the underlying Cr film layer formed on the non-magnetic substrate using Cr target! - Although this was carried out by placing a pellet of the additive on top, it was confirmed that similar effects could be obtained even if an alloy in which these additives were added to Cr in advance was used as the target.

Experimental Example 2 The disks of each magnetic recording medium created in Experimental Example 1 were 5M.
The S/N ratio when recording and reproducing on IIz was fixed at n1. The results obtained are shown in FIG.

As is clear from FIG. 2, by adding at least P to the Cr film, the S/N ratio was improved by 3 to 6 dB compared to the case where no addition was made. Also, by adding P and 81 together to Cr, the S/N ratio was further improved compared to adding P alone. This is thought to be due to the improved coercive force of the magnetic recording medium.

Comparative Experimental Example W was added instead of the above-mentioned additive to the underlying Cr film formed on the non-magnetic substrate.

Using V, No, and TI, the amount added was lat%, respectively.
A magnetic recording medium was produced in the same manner as in Experimental Example 1 except for the following. Then, the coercive force of each of the obtained magnetic recording bodies was measured in the same manner as in Experimental Example 1. All the resulting nodules are shown in Figure 3.

As is clear from Figure 3, it has been confirmed that when at least the elements W, V, No, and TI are used as additives to the underlying Cr film, the coercive force of the magnetic recording material obtained does not improve but rather decreases. It was done.

(Effects of the Invention) As described above, when using the magnetic recording body of the present invention, by adding at least P to the Cr film on the non-magnetic substrate, the Cr film structure formed on the non-magnetic substrate has a columnar structure. becomes clear and the isolation effect between each particle increases, and the isolation between the particles of the Co alloy film formed on the Cr film progresses. It has the effect of improving coercive force compared to the body.

[Brief explanation of the drawing]

Fig. 1 is a characteristic diagram showing the relationship between the coercive force of the magnetic recording body and the change in the amount of additive added in the experimental example of the present invention, and Fig. 2 is the S/N of the magnetic recording body of the present invention during recording and reproduction of the disk.
Characteristic diagram showing the relationship between the ratio and the change in the amount of added elements, Part 3
The figure is a characteristic diagram showing the relationship between the coercive force of a magnetic recording medium and additive elements in a comparative experimental example. Heisei Year Month Day

Claims (1)

[Claims] 1. A longitudinal recording type magnetic recording body comprising a Cr film and a Co alloy film successively formed on a non-magnetic substrate, characterized in that at least P is added to the Cr film.