JPS6297154A - Production of photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To produce a photomagnetic recording medium having a uniform compsn. distribution and coercive force distribution by changing the compsn. ratio of the rare earth metal and transition metal of a sputtering target material consisting of a rare earth transition metal alloy. CONSTITUTION:The sputtering target material 12 is densely disposed with square doughnut-shaped TbFeCo alloys 1 on the concentrical circle and is adhered into a rear plate 2. The compsn. ratios of Tb, Fe and Co in the respective alloy are different. A substrate 6 is mounted on a substrate holder 3 and the inside of a vacuum vessel 4 is evacuated by a vacuum evacuation device 11. Gaseous Ar is introduced into the vessel 4. A voltage is impressed by a hihg- frequency power source 9 or Dc power source 10 to a cathode electrode holder 8. Since a magnetic field is generated by an N pole magnet 14 and S pole magnet 13, magnetron discharge is generated on the sputtering target material 12 and the material 12 is released by sputtering, by which the thin TbFeCo magnetic film is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a magneto-optical recording medium that performs thermomagnetic recording erasure and magneto-optical reproduction using laser light or the like.

BACKGROUND OF THE INVENTION In recent years, much research and development has been conducted on optical recording media that have features such as high density, large capacity, and high speed access.

Among them, rewritable magneto-optical recording media are considered to be particularly promising for applications such as file memories for text and image information, rewritable video discs and compact discs, and computer external memories.

Currently, GdFe, GdTbFe, TbFeCo
, Rare-earth transition metal alloys such as GdCo are the focus of material studies, and are fabricated by vacuum evaporation methods, sputtering methods, etc. (for example, JP-A-56-126907
Publication No.).

Conventionally, magneto-optical recording media have been produced by binary evaporation using rare earth metals and transition metals as independent evaporation sources, or by sputtering using a composite target material in which small pieces of rare earth metal are placed on a transition metal plate. . However, these manufacturing methods have problems in terms of mass productivity and cost due to poor stability of the evaporation source and composite target material.

Recently, as a method to solve these problems, a target material made by alloying rare earth metals and transition metals has been developed, and prospects for mass production and cost are increasing.

Problems to be Solved by the Invention Alloys of rare earth metals and transition metals are produced by pulverizing each metal, uniformly mixing the powders, and solidifying them. Therefore, almost no compositional segregation is observed in the alloy target, and a uniform alloy target material can be obtained.

However, when sputtering a target material made of an alloy of rare earth metals and transition metals, the dependence of the release angle of the rare earth metal elements and the transition metal elements is different. The magneto-optical recording medium produced by this method has a composition distribution.

This situation will be explained using drawings. FIG. 6 is a schematic diagram of a canned electrode of a magnetron sputtering device. In FIG. 6, 12 is a disk-shaped TbFeC.

An alloy sputtering target material, 13 is a cylindrical S-pole magnet, and 14 is a square donut-shaped N-pole magnet.

Disc-shaped TbFeC with compositional segregation of o, 1 at% or less.

When the alloy sputtering target material is assembled into a cand electrode having the configuration shown in FIG. 6 and magnetron discharge is performed, the area indicated by diagonal lines on the surface of the TbFeCo alloy sputtering target material in FIG. 5 becomes an ion collision surface.
TbFeCo is sputtered and released from this surface.

This released TbFeCo was deposited on a substrate placed on a target material to produce a TbFeCo film.

FIG. 6 shows the Tb composition distribution of this TbFeCo film.

In Figure 6, the vertical axis is the composition ratio of Tb, and the horizontal axis is the disk-shaped Tb.
It shows the radial position on the substrate when the center is the intersection of the disk center axis of the FeCo alloy sputtering target material and the substrate surface.

For example, the literature "Magnetic Properties of Amorphous Alloy Films on Fe with G
d, Tb, Dy, Ho or ErJ ((Ma
gnetic Properties of Amor
phousAl, fl, oy FLlms of Fe
with Gd, Tb, Dy, H.

or Er) Y, Miura, N, Ima
Mura, T., Kobayashi.

A, 0kada and Y, Kushiro 1
, Appj! , Physics 4 (1978) 1208
), the magnetic properties of a magneto-optical recording medium made of a rare earth-transition metal alloy, such as saturation magnetization, coercive force, Curie temperature, etc., depend on the composition ratio of rare earth metals and transition metals. Change. In particular, the coercive force is very sensitive to this composition ratio, and a slight difference in the composition ratio can cause a large change in the coercive force. Therefore, when the Tb composition distribution shown in FIG. 6 is obtained, the coercive force becomes the distribution shown in FIG. 7. 7th
In the figure, the vertical axis is the coercive force, and the horizontal axis is the radial position on the substrate, which is the same as in Figure 6.0 In a magneto-optical recording medium, the magnetic bias value and laser power value during recording and erasing are Therefore, if a magneto-optical recording medium made from an alloy target material has a compositional distribution, it becomes very difficult to set recording and erasing conditions.

In view of the above-mentioned problems, the present invention provides a manufacturing method that eliminates the composition distribution of a magneto-optical recording medium and can produce a magneto-optical recording medium with a small distribution of magnetic properties.

Means for Solving the Problem In order to solve this problem, the method for manufacturing a magneto-optical recording medium of the present invention uses a sputtering device to prepare a disc-shaped rare earth transition metal alloy target material whose composition ratio changes in the radial direction. The structure is used for canned electrodes.

Function: With this configuration, the angular dependence of sputtered emission of rare earth metals and transition metals is alleviated by the difference in the number of sputtered particles of rare earth metals and transition metals, resulting in a small distribution of composition ratio and uniformity of coercive force. It is possible to manufacture all magneto-optical recording media with guaranteed properties.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional perspective view of a main part of a sputtering target material in an embodiment of the present invention.

In FIG. 1, 1 is a square donut-shaped TbFeCo alloy having a uniform composition ratio, and 2 is a back plate. Square donut-shaped TbFeCo alloys 1 are densely arranged on concentric circles and bonded on the back plate 2, and are made of Tb, Fe, and C, respectively.
The composition ratio of o is different.

FIG. 2 is a schematic cross-sectional view of the magnetron sputtering apparatus. In FIG. 2, 3 is a substrate holder, 4 is a vacuum chamber, 5 is an Ar gas supply device, 6 is a substrate, 7 is a shutter, 8 is a canned electrode holder, 9 is a high frequency power source, 10
1 is a DC power supply, and 11 is a vacuum exhaust device. Note that 12 is a disc-shaped TbFeC.

Alloy sputtering target material, 13 is a cylindrical south pole magnet, 14 is a square donut shaped north pole magnet, which is the same as that shown in FIG. 6. The method for manufacturing the magneto-optical recording medium will be described below. The sufficiently cleaned substrate 6 is mounted on the substrate holder 3, and the inside of the vacuum chamber 4 is evacuated by the vacuum evacuation device 11. Ar gas is introduced into the vacuum chamber 4 using the Ar gas supply device 5 . A voltage is applied to the canned electrode holder 8 using a high frequency power supply 9 or a DC power supply of 1°.

This generates an electric field on the sputtering target material 12. In addition, since a magnetic field is generated by the N-pole magnet 14 and the S-pole magnet 13, the sputtering target material 1
A magnetron discharge occurs on the sputtering target material 12, and the sputtering target material 12 is sputtered.

The above-described sputtering emission is performed using the TbFeCo alloy sputtering target material shown in FIG.

The shutter 7 is closed to perform bliss sputtering for a predetermined time, and then the shutter 7 is opened to deposit TbFeCo on the substrate θ.
Fabricate a magnetic thin film.

FIG. 3 shows T in one embodiment of the present invention shown in FIG.
b shows the Tb composition distribution of the FeCo alloy sputtering target material. In FIG. 3, the vertical axis represents the Tb composition ratio, and the horizontal axis represents the radial position of the sputtering target material.

TbFec has the composition distribution characteristics shown in FIG.

Sputtering target material 1 for a magnetron sputtering device showing an alloy sputtering target material in FIG.
2, and a TbFeCo magnetic thin film, which is a magneto-optical recording medium, was produced using the above method. FIG. 4 shows the coercive force distribution of a TbFeCo magnetic thin film produced using a TbFeCo alloy sputtering target material in one embodiment of the present invention. In FIG. 4, the vertical axis is the coercive force, and the horizontal axis is the substrate radial position, which are the same as in FIG. 7 of the conventional example.

As described above, according to this example, square donut-shaped FbFeCo alloys with slightly different compositions are combined,
By providing a composition distribution in the radial direction of the sputtering target material, a magneto-optical recording medium having a uniform composition and coercive force can be manufactured.

In this example, the material of the sputtering target material was a T b Fe Co alloy, but the material of the sputtering target material may be any alloy whose main components are rare earth metals and transition metals, such as GdTbFe or TbDyFe. The same effect as in the example can be obtained.

Effects of the Invention The present invention makes it possible to produce a magneto-optical recording medium having a uniform composition distribution and coercive force distribution by changing the composition ratio of rare earth metals and transition metals in a rare earth transition metal alloy sputtering target material in the radial direction. Furthermore, it is possible to realize an excellent method for manufacturing a magneto-optical recording medium, which has the effect that only the sputtering target material needs to be changed, and there is no need to modify the conventional manufacturing apparatus for a magneto-optical recording medium.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional perspective view of a main part of a sputtering target material according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view of a magnetron sputtering device, and FIG. 3 is a Tb composition distribution of the sputtering target material shown in FIG. 1. FIG. 4 shows a magneto-optical recording medium TbFeC manufactured according to an embodiment of the present invention.
o Coercive force distribution diagram of a magnetic thin film, Figure 6 is a schematic diagram of a cathode electrode of a conventional magnetron sputtering device, Figure 6 is a Tb composition distribution of a magneto-optical recording medium TbFeCo magnetic thin film produced using a conventional sputtering target material Figure, 7th
The figure is a coercive force distribution diagram of a magneto-optical recording medium TbFeCo magnetic thin film produced using a conventional sputtering target material. 1... TbFeCo alloy, 2... Back plate, 3... Substrate holder, 4... Vacuum chamber, 6... AI gas supply device, 6...Substrate, 7...Shutter, 8...Cathode electrode holder, 9...High frequency power supply, 1o...
...DC power supply, 11... Vacuum exhaust device, 1
2...Sputtering target material, 13...
...S pole magnet, 14...N pole magnet. Name of agent: Patent attorney Toshio Nakao and 1 other person +-
J5FeCo'Fk Figure 1 2-. 3 cores 2nd figure 6 figure base + feeding spirit - figure 7 I life 4 Seri & crawl

Claims (1)

[Claims] 1. A method for manufacturing a magneto-optical recording medium, comprising using a disc-shaped sputtering target material containing one or more rare earth metals and one or more transition metal elements, the composition ratio of which depends on the radial position.