JPS60197967A - Optical recording medium - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the recording and reproducing characteristics due to the oxidation of a recording layer and to improve the corrosion resistance by forming an optical recording layer on a substrate, and then plasma-etching the surface of the recording layer to form an auxiliary layer without exposing the recording layer to the atmosphere. CONSTITUTION:A thin film of an alloy of a rare earth and a transition metal, especially an amorphous magnetic film of GdTbFeCo having a large Kerr rotation angle and about 150 deg.C Curie point, is formed directly, or through an underlying layer 2 by request, on a plastic substrate 1a on the writing side as a recording layer 3. Then the recording layer 3 is plasma-etched in the atmosphere of a mixed gas consisting of one or >=2 kinds among gaseous He, Ar, or Ne, and then an SiO2 film is formed as a protective layer 4 while preventing the exposure to the atmosphere. Then a reflector film 5 of Al, etc. is successively formed, and the combined layers are stuck to an external plastic substrate 1b by using a silicone adhesive 6 to obtain an optical magnetic recording medium. The extremely durable recording medium whose magnetic characteristics are not deteriorated even under high-temp. and high-humidity conditions is obtained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical recording medium on which recording and reproduction can be performed using a light beam.

Conventionally, optical recording media used in optical discs include rare earth-transition metal alloy thin films, reducing oxide thin films such as chalcogen compounds that utilize phase transition from amorphous to crystalline, heat mode recording media, Thermoplastic recording media and the like are known. For example, as a magneto-optical recording medium formed of a rare earth-transition metal alloy thin film, Mn
B1 + polycrystalline thin film such as MnCuB+, GdCo
+ GdFe + TbFe + DyFe rGdT
Amorphous thin films such as bFe, TbDyFe, GdIG
Single crystal thin films such as

Among these thin films, there are various issues such as film formability when manufacturing large-area thin films at temperatures near room temperature, writing efficiency for writing signals with small photothermal energy, and readout of written signals with a good S/N ratio. Recently, the amorphous thin film is considered to be excellent as a photothermal recording medium in consideration of read efficiency and the like. GdTbFe has a large Kerr rotation angle and a Curie point of around 150° C., so it is suitable as a photothermal magnetic recording medium. Furthermore, as a result of research aimed at improving the Kerr rotation angle by 7, the inventors found that GdTbFeCo
It has been found that this is a magneto-optical recording medium that has a sufficiently large Kerr rotation angle and can be read with a good S/N ratio.

However, the amorphous magnetic materials used in magneto-optical recording media, such as GdTbFe, generally have a drawback of poor corrosion resistance. That is, when it comes into contact with air or water vapor, its magnetic properties deteriorate, and eventually it becomes completely oxidized and becomes transparent. Further, such deterioration of recording/reproducing characteristics due to oxidation of the optical recording layer has been a common problem in magneto-optical recording media.

In order to eliminate such drawbacks, a protective cover of transparent material, such as 5102, Si
It has been proposed to provide a protective layer of O.

However, in conventional manufacturing methods for optical recording media, after forming an optical recording layer, it is exposed to the atmosphere once, and after a certain period of time, an auxiliary layer such as a protective film or an anti-reflection film is applied. was forming. Therefore, oxidation progressed from the interface between the optical recording layer and the auxiliary layer exposed to the atmosphere, making it impossible to obtain sufficient corrosion resistance. In particular, when the optical recording layer consists of a very thin magnetic layer with a thickness of several hundred layers, the magnetic properties, transmittance, etc. deteriorate significantly when left for a long time. In addition, the recording/reproducing characteristics of the optical recording layer vary depending on the history up to the formation of the auxiliary layer, and there is a drawback that variations occur between finished optical recording media.

An object of the present invention is to provide a method for manufacturing an optical recording medium that provides an optical recording medium with excellent corrosion resistance and uniform characteristics.

The above object of the present invention is to provide a method for manufacturing an optical recording medium in which an undercoat layer is optionally provided on a substrate, and then an optical recording layer and an auxiliary layer are sequentially laminated. This is achieved by subsequently forming an auxiliary layer after plasma etching.

According to the method for manufacturing an optical recording medium of the present invention, for example, even if the optical recording layer is a magnetic layer with a thickness of several hundred layers, sufficient ttX corrosion resistance, reproducibility, and uniformity between media can be achieved. I was able to gain sex.

Plasma etching of the recording magnetic layer in the present invention is carried out using an inert gas, preferably He, A
This is carried out using r or Ne, or a mixed gas of two or more thereof. The degree of etching is 50X to 300X
Therefore, for the purpose of the present invention, it is preferable to form the optical recording layer in advance to be thicker than a predetermined thickness by the above range, and then to etch it until the predetermined thickness is reached. After etching, the etching surface is not exposed to the atmosphere until the auxiliary layer is formed.

The auxiliary layer is usually MgFt + AA'208 r
ZrO2.

Materials such as Si, N, lAIN, Sin, SiO, etc. are used, and a SiO film is particularly preferred.

The present invention will be further explained below with reference to Examples.

Example 1 In FIG. 1, an acrylic resin plate is used as the writing-side plastic substrate 1a, and the undercoat layer 2 is approximately 1O
An OOX SiO film was formed to serve as a recording magnetic layer.
A quaternary amorphous magnetic film of X was formed.

This was once exposed to the atmosphere and then heated to 5 x 1O-3 Torr before forming the SiO film as the protective layer 4 again.
The recording magnetic layer 6 was etched from 250X to 20OA by plasma etching in an argon gas atmosphere. After that, S is added as a protective layer without being exposed to the atmosphere.
An iO film was formed. After that, AI is sequentially used as the reflective film 5.
A silicon-based adhesive was used as the film and adhesive layer 6, and the film was bonded to an external plastic substrate 1b via the adhesive layer 6 to obtain a magneto-optical recording medium.

The five magneto-optical recording media produced have a rotation angle θK and a coercive force H.
The results of a moisture resistance test under the conditions of 45°C, 95% relative humidity, and 200 hours of standing time with the same value for both e,
No deterioration of magnetic properties was observed, and durability was improved.

In the above-mentioned embodiments, the case where a magneto-optical recording medium is manufactured has been described, but the present invention is not limited to this, and can be applied to any recording medium having an optical recording layer that is easily oxidized. In addition to the above protective layer, the auxiliary layer may include a heat insulating layer, etc.
Various things are possible.

Further, in the present invention, the optical recording layer may be exposed to the atmosphere after the optical recording layer is formed, so the optical recording layer is particularly formed. This is effective when the vacuum chamber and the vacuum chamber in which the auxiliary layer is formed are different.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram for explaining an example of the configuration of an optical recording medium manufactured according to the present invention. 1a...Writing side plastic substrate 1b...External plastic substrate 2...Undercoat layer 6...Recording magnetic layer 4...Protective layer 5...・Reflective layer 6... Adhesive layer patent - Patent applicant: Canon Co., Ltd., Company Figure 1

Claims (3)

[Claims] (1) In a method for manufacturing an optical recording medium in which an undercoat layer is provided on a substrate as desired, and then an optical recording layer and an auxiliary layer are sequentially laminated, the surface of the optical recording layer is plasma etched. , a method for producing an optical recording medium, which comprises subsequently forming an auxiliary layer. (2) The plasma etching is performed using He+Ar and N.
2. The method for manufacturing an optical recording medium according to claim 1, wherein the method is carried out using one type of e-gas or a mixture of two or more of the gases. (3) The method for manufacturing an optical recording medium according to claim 1, wherein the vacuum chamber in which the optical recording layer is formed and the vacuum chamber in which the auxiliary layer is formed are different.