JPH07192244A - Perpendicular magnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To produce a magnetic recording medium excellent in recording and reproducing characteristics in a high density recording region, having stable magnetic characteristics and excellent in mass productivity by disposing a platinum film as an under film. CONSTITUTION:An under film 2 of platinum is formed on a nonmagnetic substrate 1 by sputtering in >=100Angstrom thickness and a Co-Cr alloy film 3 is formed on the under film 2 to produce the perpendicular magnetic recording medium. The crystallinity and orientability of the Co-Cr alloy film 3 are enhanced and perpendicularly magnetizing characteristics are improved. Since the rate of sputtering of Pt is relatively high, a long time is not required to form the platinum film 2 and this method is advantageous to the mass production of the perpendicular magnetic recording medium.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perpendicular magnetic recording medium having a Co--Cr alloy as a magnetic layer.

[0002]

2. Description of the Related Art In recent years, in the field of magnetic recording, higher density recording has been promoted, and in the recording system as well, the in-plane magnetic recording system using a magnetic recording medium having an easy axis of magnetization in the plane has been used. A perpendicular magnetic recording system using a magnetic recording medium having an easy axis of magnetization in the direction perpendicular to the plane is being shifted.

That is, in the in-plane magnetic recording medium, the demagnetizing field increases as the recording density increases, and therefore there is a limit to the high recording density, whereas in the perpendicular magnetic recording medium, the high recording density increases. On the contrary, the magnetic recording medium has a characteristic that the demagnetizing field becomes small and the magnetization is stabilized. By using such a perpendicular magnetic recording medium, it becomes possible to dramatically increase the recording density.

As the magnetic layer of the perpendicular magnetic recording medium,
An alloy thin film in which a Co-based alloy having an hcp structure is oriented so that the C axis which is the easy axis of magnetization thereof is perpendicular to the film surface is used, and for example, a Co—Cr alloy thin film is common.

By the way, in the perpendicular magnetic recording medium using the alloy thin film as described above, it is important that the alloy thin film has good crystallinity and orientation, and the alloy thin film improves the crystallinity and orientation. As a result, a perpendicular magnetic anisotropy field sufficient to overcome the demagnetizing field in the film thickness direction is exhibited.

Here, when the alloy thin film is formed directly on the non-magnetic support, the fine structure of the alloy thin film is adversely affected by the support material, and the crystallinity and orientation are deteriorated. For this reason,
In the above perpendicular magnetic recording medium, a base film is provided on a non-magnetic support, and an alloy thin film is formed on the base film. For example, when a Co—Cr alloy thin film is used as a magnetic layer, a Ti film having an hcp structure is provided as a base film, like the Co—Cr alloy film.

[0007]

However, Co-Cr
When a Ti film is provided as a base film of an alloy thin film, Co-C
The r-alloy thin film improves the perpendicular coercive force due to the change of the film structure, but the crystallinity and orientation are hardly improved. In the perpendicular magnetic recording medium, it is required that the coercive force is appropriate, but it is important that the alloy thin film has good crystallinity and orientation. In particular, the characteristics of the high-density recording area largely depend on the crystallinity and orientation of the alloy thin film.

The Ti film is usually formed by sputtering, but since Ti is chemically highly active and is easily combined with the residual gas in the vacuum chamber during sputtering, the fine structure is likely to change. For this reason, when the Ti film is used as the base film, the magnetic characteristics of the Co—Cr alloy film become unstable. Further, since the Ti underlayer film has a low sputtering rate of Ti, it takes time to form the film, which is an obstacle to mass production.

Therefore, the present invention has been proposed in view of such a conventional situation, and has excellent recording / reproducing characteristics in a high-density recording area and stable magnetic characteristics, and magnetic recording excellent in mass productivity. The purpose is to provide a medium.

[0010]

Means for Solving the Problems As a result of intensive studies by the present inventors, it was found that Co-Cr was not achieved.
As a base film of the alloy film, the lattice plane of the orientation direction is (0) of the Co--Cr alloy film rather than the hcp structure.
002) It came to the idea that it is important that there is little misfit with respect to the lattice plane. On the basis of this idea, the Pt film having a lattice plane in the orientation direction with a small misfit to the (0002) lattice plane of the Co—Cr alloy film [fcc structure, (1
11) orientation] was formed as a base film, Co--C
The crystallinity and orientation of the r alloy film were improved, and the recording / reproducing characteristics in the high density area were excellent.

The present invention has been completed on the basis of the above findings, and a base film, Co and Cr are formed on a non-magnetic support.
In a perpendicular magnetic recording medium formed by stacking alloy films containing as a main component, the underlayer film is a platinum film. The platinum film has a thickness of 100 Å or more. Further, according to the manufacturing method of the present invention, when a platinum film and an alloy film containing Co and Cr as main components are formed on a non-magnetic support to manufacture a perpendicular magnetic recording medium, the platinum film is formed by sputtering. It is characterized by doing.

The perpendicular magnetic recording medium of the present invention, as shown in FIG. 1, has a platinum underlayer 2 and a Co--Cr film on a non-magnetic support 1.
The system alloy film 3 is formed. Co-C above
r alloy film 3 is made by forming an alloy sputtering or the like mainly composed of Co and Cr, As the alloys such as Co _x Cr _y M _z (where, M is Ta,
W, Re, Nb, Mo, V, and x + y + z = 100
Alloys represented by atomic%) is used, in particular Co _x Cr _y
The Ta _z alloy is suitable because of its large coercive force.

In Co _x C _y M _z , the composition ratio x (atomic%) of Co is preferably 75 ≦ x ≦ 85.
When the composition ratio x of Co is less than 75 atom%, the magnetism is small and the function as a magnetic layer is insufficient, and when x is more than 85 atom%, it is not suitable for the perpendicular magnetic recording system. Become. Further, the composition ratio z (atomic%) of M is 0 ≦ z
<5 is preferable. When the composition ratio z of M exceeds 5 atomic%, the perpendicular magnetic anisotropy is deteriorated and the magnetization is decreased, which is also insufficient as a magnetic layer.

In the present invention, the platinum film 2 is provided as a base film for such a Co--Cr alloy film 3. By providing the platinum film 2 as a base film, the Co—Cr alloy film 3 has improved crystallinity / orientation and a large perpendicular magnetic anisotropy field.

The thickness of the platinum film 2 is preferably 100 Å or more. If the layer thickness of the platinum film 2 is less than 100Å, the effect of the platinum film is not sufficiently exerted, and the microstructure of the Co—Cr alloy film may be deteriorated due to the influence of the substrate.

Although the above is the basic constitution of the present invention, the present invention may be applied to a perpendicular magnetic recording medium in which the magnetic layer is composed of two layers of a soft magnetic film and a Co--Cr alloy film. . In this case, the platinum film is provided between the soft magnetic film and the Co—Cr alloy film, and the non-magnetic support, the soft magnetic film, the platinum film, and the Co—C film are provided.
The r alloy films are sequentially laminated.

[0017]

In a perpendicular magnetic recording medium having a Co-Cr alloy film as a magnetic layer, when a platinum film is provided as a base film of the Co-Cr alloy film, the crystallinity and orientation of the Co-Cr alloy film are improved. However, the perpendicular magnetization characteristic becomes good. Co-C of hcp structure even though platinum film has fcc structure
The fcc can improve the crystallinity and orientation of the r-based alloy film.
Structure of (111) lattice plane of platinum film and hcp structure of Co-
It is considered that the misfit of the (0002) lattice plane of the Cr alloy film is small.

Further, the platinum film has a high effect of blocking the gas released from the organic material-based support, and this is also due to Co--Cr.
Contributes significantly to improving the crystallinity and orientation of the Al-based alloy film.

Since platinum is chemically stable in the platinum film, the platinum film is formed with a stable structure that is not easily affected by the residual gas in the vacuum chamber when the film is formed by sputtering. Therefore, by using the platinum film as the base film, the magnetic characteristics of the Co—Cr alloy film are also stabilized. Moreover, since the platinum film has a relatively high Pt sputtering rate,
The film formation does not require so much time, which is advantageous for mass production of the perpendicular magnetic recording medium.

[0020]

EXAMPLES Preferred examples of the present invention will be described based on experimental results.

Examination of crystallinity / orientation of Co—Cr alloy film On a slide glass, a base film having a film thickness of 30 nm and a film thickness of 10
nm Co-Cr alloy film was sequentially formed to prepare a sample alloy film. As the sample alloy film, the underlying film is a Pt film (sample alloy film 1), the underlying film is an Au film having a fcc structure similar to Pt (sample alloy film 2), and the underlying film is Co—Cr. Similar to the alloy film, three types of Ti film (sample alloy film 3) having an hcp structure were prepared.

The film forming conditions for the Co--Cr alloy film are as follows. Co-Cr alloy film forming conditions Film forming method: high frequency magnetron sputtering method Target: Co ₇₉ Cr ₂₁ alloy target Input power: 300 W Ultimate vacuum degree: 3 x 10 ^-3 Pa Sputtering gas pressure: 0.8 Pa Substrate temperature: room temperature ( Water-cooled substrate holder used)

The crystallinity and orientation of each of the sample alloy films thus prepared were evaluated by examining the X-ray diffraction (Cu: Kα) pattern.

The X-ray diffraction patterns of the respective sample alloy films are shown in FIGS. 2 to 4, and the orientation of the base film, the intensity of the (0002) peak and the full width at half maximum Δθ ₅₀ obtained from the X-ray diffraction patterns are shown.
Is shown in Table 1.

[0025]

[Table 1]

First, looking at the X-ray diffraction pattern of the sample alloy film 1 shown in FIG.
From the Pt film of fcc structure, (111) and (222)
Only the peak is observed, which shows that the Pt film is strongly oriented in (111). On the other hand, Co-Cr with hcp structure
A (0002) peak is observed from the alloy film. As shown in Table 1, the (0002) peak of this Co—Cr alloy film has a large strength and a narrow half width Δθ ₅₀ . This indicates that the Co—Cr alloy film of the sample alloy film 1 has excellent crystallinity and orientation.

Looking at the X-ray diffraction pattern of the sample alloy film 2 shown in FIG. 3, a weak (113) peak is observed along with the (111) peak from the Au film, and the Au film is as strong as the Pt film (111). ) It turns out that it does not show orientation.
On the other hand, as shown in Table 1, the (0002) peak observed from the Co—Cr alloy film has a weak diffraction intensity and a large Δθ ₅₀ . This means that the Co—Cr alloy film of the sample alloy film 2 has a crystallinity / orientation of Co—Cr of the sample alloy film 1.
It is lower than the alloy film.

The X-ray diffraction pattern of the sample alloy film 3 shown in FIG. 4 is observed from the Co--Cr alloy film (0
The 002) peak has a small diffraction intensity and a large Δθ ₅₀ as shown in Table 1. From this, the sample alloy film 3
Is the Co-Cr alloy film of the sample alloy film 1.
It can be seen that the crystallinity and orientation are lower than those of the alloy film.

Further, the (111) lattice plane of the Pt underlayer and the (0002) lattice plane of the Co--Cr alloy film, the (111) lattice plane of the Au underlayer film and the (0002) lattice plane of the Co--Cr alloy film, and Ti. Underlayer (0002) lattice plane and Co-C
The misfit of the (0002) lattice plane of the r alloy film was determined. 8 and 9 are schematic views of the (0002) lattice plane of the hcp structure and the (111) lattice plane of the fcc structure, respectively, showing the (111) lattice plane of the Pt underlayer and the (111) lattice plane of the Co--Cr alloy film. The misfit between the (0002) lattice plane, the (111) lattice plane of the Au underlayer and the (0002) lattice plane of the Co—Cr alloy film was obtained by the equation 1.

[0030]

[Equation 1]

As a result, the misfit between the (111) lattice plane of the Pt underlayer and the (0002) lattice plane of the Co--Cr alloy film was 10.7%, and the (111) lattice plane of the Au underlayer and Co
-Misfit of (0002) lattice plane of Cr alloy film is 1
5.0%, (0002) lattice plane of Ti base film and Co-C
The misfit of the (0002) lattice plane of the r alloy film is 17.
It was 7%.

From these results, P among various underlayer films was obtained.
It was found that the t film is most suitable for improving the crystallinity and orientation of the Co—Cr alloy film.

Examination of Magnetic Properties of Co—Cr Alloy Film Next, the magnetic properties of the sample alloy film having the Pt film as a base film were evaluated.

First, a film thickness of 90 nm is formed on a slide glass.
A Pt base film and a Co—Cr alloy film were sequentially formed to prepare a sample alloy film. The film thickness of the Co—Cr alloy film was changed to 10 nm, 22 nm, and 88 nm. The conditions for forming the Co—Cr alloy film are the same as those described above. Then, regarding the prepared sample alloy film, Ke
The perpendicular magnetization curve was investigated by rr loop tracer. The results are shown in FIGS.

As can be seen from FIGS. 5 to 7, each of the sample alloy films using the Pt film as a base film has excellent squareness.

Therefore, from the above results, Co--Cr
Providing a Pt film as a base film of the alloy film is Co-C
It is effective in improving the crystallinity / orientation of the r alloy film and making it excellent in perpendicular magnetization characteristics. In particular, good perpendicular magnetization is achieved even in an extremely thin region of a Co—Cr alloy film having a film thickness of about 10 nm. From the characteristics, it was found that the effect was great.

[0037]

As is apparent from the above description, in the present invention, a platinum film is provided as a base film of a Co—Cr alloy film in a perpendicular magnetic recording medium having a Co—Cr alloy film as a magnetic layer. Therefore, it is possible to obtain a perpendicular magnetic recording medium which has good perpendicular magnetization characteristics, stable magnetic characteristics, and excellent mass productivity.

Therefore, according to the present invention, it is possible to further improve the recording / reproducing characteristics in the high density region of the perpendicular magnetic recording medium and further improve the practicality.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of essential parts showing an example of a perpendicular magnetic recording medium to which the present invention is applied.

FIG. 2 is a characteristic diagram showing an X-ray diffraction pattern of a perpendicular magnetic recording medium using a Pt film as a base film.

FIG. 3 is a characteristic diagram showing an X-ray diffraction pattern of a perpendicular magnetic recording medium having an Au film as a base film.

FIG. 4 is a characteristic diagram showing an X-ray diffraction pattern of a perpendicular magnetic recording medium having a Ti film as a base film.

FIG. 5 is a perpendicular magnetization curve of a perpendicular magnetic recording medium having a Co—Cr alloy film thickness of 10 nm.

FIG. 6 is a vertical magnetization curve of a perpendicular magnetic recording medium having a Co—Cr alloy film thickness of 22 nm.

FIG. 7 is a perpendicular magnetization curve of a perpendicular magnetic recording medium having a Co—Cr alloy film thickness of 88 nm.

FIG. 8 is a schematic view showing a (0002) lattice plane of the hcp structure.

FIG. 9 is a schematic diagram showing a (111) lattice plane of an fcc structure.

[Explanation of symbols]

 1 ... Non-magnetic support 2 ... Platinum film 3 ... Co-Cr alloy film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Desmond J. Maps UK, Devon Peerle 48 AA, Plymouth, Drake Circus, South West, School of Electronic Communication and Electrical Engineering Polytechnic (no address) )

Claims (3)

[Claims] 1. A base film, Co and Cr on a non-magnetic support.
A perpendicular magnetic recording medium in which an alloy film containing as a main component is laminated, wherein the underlayer film is a platinum film. 2. The perpendicular magnetic recording medium according to claim 1, wherein the platinum film has a thickness of 100 Å or more. 3. A platinum film, Co and Cr on a non-magnetic support.
A method for manufacturing a perpendicular magnetic recording medium, characterized in that, when a perpendicular magnetic recording medium is manufactured by forming an alloy film containing as a main component, the platinum film is formed by sputtering.