JPH0551739A - Production of magneto-optical disk - Google Patents

Abstract

PURPOSE:To produce a magneto-optical disk by forming a multilayered film having high adhesion on an acrylic resin substrate. CONSTITUTION:A Pt target 14 and a Co target 16 are alternately sputtered with inert gas ion beams 20, 20 alternately extracted from two ion sources 18, 18 in a vacuum vessel to form a multilayered film consisting of Pt and Co layers on the surface of an acrylic resin substrate 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a magneto-optical disk using a multilayer film.

[0002]

2. Description of the Related Art An example of the structure of this type of magneto-optical disk is shown in FIG. This magneto-optical disk is formed by forming a multilayer film 8 of a platinum film 4 and a cobalt film 6 on a substrate 2.

As a method for forming the multilayer film 8, the vacuum vapor deposition method has a problem in film density, productivity, and the like. Therefore, conventionally, a plasma sputtering method in which a target is sputtered by plasma is mainly used.

Further, as the substrate 2, a polycarbonate substrate capable of forming the multi-layer film 8 having high adhesion even by the plasma sputtering method is conventionally used exclusively.

[0005]

However, the polycarbonate substrate has a problem that it has a large birefringence and is expensive, and an acrylic resin substrate has been studied as an alternative, but it has been used conventionally. With the plasma sputtering method, it was not possible to form a multi-layer film having high adhesion on an acrylic resin substrate.

Therefore, the main object of the present invention is to provide a method of manufacturing a magneto-optical disk capable of forming a multi-layer film having high adhesion on an acrylic resin substrate.

[0007]

In order to achieve the above object, a method of manufacturing a magneto-optical disk according to the present invention is such that at least the first layer of a multilayer film as described above is subjected to ion beam irradiation in a vacuum atmosphere. It is characterized in that the target is formed by an ion beam sputtering method for sputtering.

[0008]

The multilayer plasma film having high adhesion cannot be formed on the acrylic resin substrate by the conventional plasma sputtering method because the surface of the acrylic resin substrate is exposed to high density plasma during film formation. Deterioration (damage of the resin due to temperature) and the impurity gas released from the resin surface due to heating due to the inflow of accelerated electrons that are accelerated by the electric field to the acrylic resin substrate on the anode side causes some reaction with the film. It is thought that this is caused by things.

On the other hand, in the case of the ion beam sputtering method, in principle, plasma does not exist near the surface of the acrylic resin substrate, and accelerated electrons emitted from the plasma do not exist, so that the conventional plasma sputtering method is used. It is possible to prevent the deterioration of the acrylic resin substrate surface and the generation of the impurity gas, which are found in the method. Therefore, if such an ion beam sputtering method is used to form at least the first layer that influences the adhesion of the multilayer film, it becomes possible to form the multilayer film having high adhesion on the acrylic resin substrate. ..

[0010]

1 is a schematic view showing an example of an apparatus for carrying out a method of manufacturing a magneto-optical disk according to the present invention.

A rotary substrate holder 10 is provided in a vacuum container (not shown), and a plurality of acrylic resin substrates 2a are attached to it. Two target holders 12 are provided below the substrate holder 10, and in this example, a platinum target 14 and a cobalt target 16 are attached to the target holders 12, respectively. Also,
Two ion sources 18 for irradiating an inert gas ion beam 20 of argon, helium, neon, krypton, xenon or the like are arranged toward the targets 14 and 16, respectively. Reference numeral 22 is a shielding plate.

While the inside of the vacuum container is evacuated, while rotating the substrate holder 10, the inert gas ion beam 20 is alternately extracted from the two ion sources 18 and alternated to the platinum target 14 and the cobalt target 16. When the target is irradiated with, the platinum particles 24 and the cobalt particles 26 are alternately struck out from both the targets 14 and 16, and these are projected onto the respective acrylic resin substrates 2a on the substrate holder 10.
Are alternately incident and deposited on the acrylic resin substrate 2 to form the multilayer film 8 of the platinum film 4 and the cobalt film 6 on the acrylic resin substrate 2.

Polymethylmethacrylate (PMMA), which is a typical example of an acrylic resin substrate, is formed by the ion beam sputtering method and the conventional plasma sputtering method as described above.
P and P substrate and conventional polycarbonate (PC) substrate
Table 1 shows an example of the experimental results of forming the t / Co multilayer film.

[0014]

[Table 1]

In this table, ◯ marks indicate good, and X marks indicate defective. Further, the adhesiveness of the film was examined by a tape peeling test.

As can be seen from this table, by using the ion beam sputtering method, it is possible to form a multilayer film having high adhesion on the PMMA substrate. In addition, the reflectance of the film is about 10% compared with the case of the conventional plasma sputtering method.
(Ie (55-50 / 50) × 100%). This increases the CNR (carrier-to-noise ratio) of the magneto-optical disk by about 3%.

The above example is an example in which all of the multilayer films are formed by the ion beam sputtering method, but the most problematic problem is that of the acrylic resin substrate and the first layer film thereon. Adhesion is good, and as long as the first layer film can be formed with good adhesion, it is possible to form the second and subsequent layers on it with good adhesion by a method other than the ion beam sputtering method. is there. That is, it is important to form at least the first layer of the multilayer film, which influences the adhesion with the substrate, by the ion beam sputtering method.

The acrylic resin of the substrate may be other than PMMA.

The structure of the multilayer film is not limited to the Pt / Co multilayer film. For example, a film made of a platinum group element (for example, Pt, Pd, etc.) among transition elements and an iron group element (for example, It may be a multi-layer film of a film made of Co, Fe, Ni, etc.).

[0020]

As described above, according to the present invention, a multilayer film having high adhesion can be formed on an acrylic resin substrate, and as a result, a magneto-optical disk using the acrylic resin substrate can be put to practical use. You can Moreover, if an acrylic resin substrate is used, the birefringence can be reduced, the characteristics of the magneto-optical disk can be improved, and the cost can be reduced. Furthermore,
According to the ion beam sputtering method of the present invention, the reflectance of the multilayer film can be improved as compared with the case of the conventional plasma sputtering method, and in this sense as well, a magneto-optical disk having excellent characteristics can be obtained. ..

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of an apparatus for carrying out a method of manufacturing a magneto-optical disk according to the present invention.

FIG. 2 is a schematic sectional view showing an example of the structure of a magneto-optical disk.

[Explanation of symbols]

 2a Acrylic resin substrate 4 Platinum film 6 Cobalt film 8 Multilayer film 14 Platinum target 16 Cobalt target 18 Ion source 20 Inert gas ion beam

Claims (1)

[Claims] 1. A method of manufacturing a magneto-optical disk by forming a multilayer film on an acrylic resin substrate, wherein at least the first layer of the multilayer film is ion-sputtered with a target by an ion beam in a vacuum atmosphere. A method for manufacturing a magneto-optical disk, which is characterized in that it is formed by using a beam sputtering method.