JP2642658B2 - Manufacturing method of optical magnetic recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to light such as laser light (light as used herein means
Energy beams of various wavelengths including laser light) for recording, reproducing, and erasing information.

[Prior Art] Conventionally, a recording layer of an optical magnetic recording medium is generally manufactured by a sputtering method using an alloy target obtained by dissolving a rare earth and a transition metal into an alloy.

[Problems to be solved by the invention]

However, the above-described manufacturing method has a disadvantage that the composition of the recording layer is affected by the film forming conditions and apparatus conditions, and the composition of the recording layer differs from the alloy target composition. In addition, since the composition of the alloy target itself varies from lot to lot, it took time to determine the conditions, such as attaching a chip of a rare earth or the like to the target surface in order to obtain the required recording layer composition.

As described above, the above-mentioned manufacturing method has a disadvantage that the mass productivity is poor because the composition of the recording layer cannot be easily controlled.

[Means for solving the problem]

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method of manufacturing an optical magnetic recording medium that can easily control the composition of an optical magnetic recording layer and has good mass productivity. The present invention is a method of manufacturing an optical magnetic recording layer by a sputtering method using an alloy target, wherein the composition of the recording layer is easily controlled by changing the ratio of the ground area and the cathode area in the discharge space. It is characterized by being able to.

When the ratio between the ground area and the cathode area is large, the cathode self-bias becomes large, ions are accelerated strongly, and a transition metal that is difficult to sputter is sputtered, and a layer rich in transition metal is obtained. Conversely, when the area ratio is small, the cathode self-bias is small, the ion energy is small, and a rare earth that is easily sputtered is mainly sputtered, so that a layer rich in rare earth is obtained.

Since the cathode area is generally the area inside the alloy target, a specific embodiment of the change in the area ratio between the ground area and the cathode area in the present invention generally depends on the change in the ground area. is there.

〔Example〕

 Hereinafter, the present invention will be described specifically with reference to Examples.

FIG. 1 is a configuration diagram of an optical magnetic recording medium manufacturing apparatus for carrying out the present invention.

The vacuum tank 1 and the movable movable plate 2 are electrically connected by a jig 3, and the position of the movable movable plate 2 can be adjusted by the jig. A high-frequency power source 6 is connected to the target 5 whose side surface is protected by the guard electrode 4,
A high-frequency voltage can be applied between the target 5 and the vacuum chamber 1 and the deposition-preventing plate 2, which are not shown but are grounded. The inside of the vacuum chamber 1 is evacuated by the vacuum system 9, an argon gas is introduced from the argon inlet tube 7, and a film is formed on the substrate 8 by applying the high-frequency voltage.

The target 5 functions as a cathode electrode, and the inner surface of the vacuum chamber 1 and the inner surface of the deposition-preventive movable plate 2 excluding that portion function as ground electrodes. Therefore, the cathode area S _C corresponds to the area inside the target 5, and the ground area S _E corresponds to the inner area of the portion surrounded by the vacuum chamber 1 and the anti-adhesive movable plate 2 excluding the guard electrode 4 and the target 5. I do.

By moving the position of the adhesion-preventing movable plate 2 by the jig 3, the size of the ground area S _E changes, and (the ground area S _E )
The ratio of / (cathode area S _C ) can be changed.

Example 1 Depending on the jig 3, (earth area S _E ) / (cathode area)
The ratio of S _C ) was adjusted to 5.

A target 5 having Tb 19,3%, Fe 74.5%, Co 8.0%, diameter 130 mm, and a substrate 8 having a glass substrate diameter 130 mm were arranged at predetermined positions.

The inside of the vacuum chamber 1 is evacuated to a pressure of 1 × 10 ⁻⁵ Pa or less, and a constant flow rate of argon gas is introduced into the vacuum chamber 1 to adjust the pressure in the layer to 0.2 Pa. 8
A recording layer made of a Tb-FeCo alloy having a film pressure of 800 ° was formed thereon.

Examples 2 to 4 Tb-Fe under the same conditions as in Example 1 except that the ratio of (earth area S _E ) / (cathode area S _C ) was adjusted to 10, 20, and 30, respectively.
A recording layer made of a Co alloy was formed.

Examples 5 to 8 Gd 20%, Fe 56%, Co 24%, diameter 130m as target 5
A recording layer was formed under the same conditions as in Examples 1 to 4, except that m was used.

Table 1 shows the composition of the target used in Examples 1 to 4 and the composition of the formed recording layer.

As is clear from Table 1, the composition of the recording layer to be formed can be changed only by changing the ratio of (earth area S _E ) / (cathode area S _C ).

Further, the coercive force and saturation magnetization of the recording layers prepared in Examples 1 to 4 were measured, and the results are shown in FIG. It can be seen that the properties of the recording layer have changed with the change in the composition.

Table 2 shows the compositions of the targets and the recording layers prepared in Examples 5 to 8.

FIG. 3 shows the measurement results of the saturation magnetization of the recording layers prepared in Examples 5 to 8.

Table 2 and FIG. 3 also show that the composition and properties of the formed recording layer can be changed by changing the ratio of (earth area S _E ) / (cathode area S _C ).

〔The invention's effect〕

As described above, according to the present invention, the composition of the optical magnetic recording layer can be easily controlled, a desired composition can be easily obtained, and improvement in mass productivity can be expected.

Even if the composition of the alloy target changes, the composition of the recording layer can be adjusted to the desired composition according to the present invention. Therefore, in the manufacturing process of the alloy target, the composition allowable range can be widened, and as a result, the manufacturing cost of the alloy target is expected to be reduced. it can.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical magnetic recording medium manufacturing apparatus for carrying out the present invention. FIG. 2 shows the results of measuring the coercive force and the saturation magnetization of the Tb-FeCo recording layers prepared in Examples 1 to 4. FIG. 3 shows the results of measuring the saturation magnetization of the Gd—FeCo recording layers prepared in Examples 5 to 8. 1: Vacuum tank 2: Movable plate 3: Jig 4: Guard electrode 5: Target 6: Alternating frequency power supply 7: Argon introduction tube 8: Substrate 9: Vacuum system

Claims (1)

(57) [Claims] 1. A method for producing, by sputtering, an optical magnetic recording medium which is made of an amorphous material containing a rare earth element and a transition metal and which becomes a recording layer having an easy axis of magnetization perpendicular to the substrate surface, comprising: Wherein the composition of the recording layer is arbitrarily controlled by changing the area ratio between the ground area and the cathode area in the discharge space.