JPH0863790A - Optical disk - Google Patents

Abstract

PURPOSE: To provide an optical disk formed with a reflection film having a good adhesion property on an acrylic resin substrate featuring lightweightness, ease of working and excellent mass productivity by a sputtering method with good productivity. CONSTITUTION: An annular conductive supporting frame material 11 having a shape in contact with the entire part on the substrate side surface and having a thickness higher than the thickness of the substrate 6 is disposed on a sputtering device provided with an annular auxiliary electrode 5 between a substrate holder 3 and a target 4 or on this substrate holder 3. The metallic reflection film of aluminum or aluminum alloy is formed on the acrylic resin substrate 6 by this sputtering device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc having excellent adhesion between a substrate and a metal reflective film.

[0002]

2. Description of the Related Art Currently, glass and plastic (resin) are used as materials for optical disk substrates, but they are lightweight and
The latter is mainly used because of its ease of processing and mass productivity. Among them, acrylic resins have extremely excellent optical characteristics and are currently used in laser disks and the like.

An optical disk such as a laser disk is a resin substrate having pits on its surface and a metal film such as aluminum or aluminum alloy attached as a reflective film. As a method of forming a metal reflective film on a resin substrate for optical disks, there are mainly a vacuum vapor deposition method and a sputtering method.

The sputtering method has advantages such as high productivity, but when an acrylic resin substrate is used, the sputtering method has a problem that a reflective film having good adhesion cannot be obtained. ing.

Therefore, when an acrylic resin substrate is used, a vacuum evaporation method has been conventionally used for forming a metal reflective film on the substrate.

[0006]

SUMMARY OF THE INVENTION The present invention has been made based on the above background, and an object of the present invention is to produce an acrylic resin substrate which is lightweight, easy to process, and excellent in mass productivity. Another object of the present invention is to provide an optical disc having a reflective film having good adhesion formed by a sputtering method having good properties.

[0007]

The gist of the present invention is to provide a sputtering device having a ring-shaped auxiliary electrode between a substrate holder and a target, or a shape in which the entire side surface of the substrate is contacted on the substrate holder. In addition, the metal reflective film of aluminum or aluminum alloy is formed on the acrylic resin substrate by a sputtering device provided with a ring-shaped conductive support frame material having a thickness higher than that of the substrate. It is on the optical disc.

The sputtering method used in the present invention is to ionize an inert gas such as argon introduced into a vacuum chamber, collide it with a solid surface called a target to which a voltage is applied, and knock out solid particles to produce a substrate. This is a method of forming a film on top. The method of generating plasma is classified into direct current sputtering, high frequency sputtering and the like, and the present invention can be applied to any method.

The sputtering apparatus according to the present invention is a ring-shaped conductive member having a shape in which the auxiliary electrode is provided between the substrate holder and the target, or the entire side surface of the substrate is in contact with the substrate holder and has a thickness higher than that of the substrate. A material provided with a sexual support frame material is used.

When the auxiliary electrode is provided between the substrate holder and the target, the place where the auxiliary electrode is installed is not particularly limited, but it is usually installed near the intermediate portion between the substrate holder and the target.

The shape of the auxiliary electrode is not particularly limited as long as it is ring-shaped, but a material having a diameter similar to that of the substrate is usually used.

The material of the auxiliary electrode is not particularly limited as long as it has good conductivity, and examples thereof include copper and copper alloys.

The potential applied to the auxiliary electrode can be arbitrarily set according to the specifications of the apparatus, the plasma generation method, etc., and not only the positive potential but also the negative potential can be set or grounded.

In the present invention, the object of the present invention can be achieved by a method of providing a ring-shaped conductive support frame material on the substrate holder instead of installing the auxiliary electrode.

As shown in FIG. 2, the conductive support frame member needs to be in contact with the entire side surface of the substrate.

Further, the thickness of the conductive supporting frame material is required to be higher than the thickness of the base material, preferably 5 to 10 mm.

The material of the conductive support frame material is not particularly limited as long as it has good conductivity like the auxiliary electrode, and examples thereof include copper and copper alloys.

Aluminum or an aluminum alloy is used for the reflecting film in the present invention. If necessary, a multilayer structure film in which at least the vicinity of the interface of the reflecting film with the substrate is oxidized aluminum or aluminum alloy is used. Is also good.

Usually, if the thickness of the reflective film formed on the acrylic substrate is too large, the adhesion tends to decrease,
Compared with the case where the reflective film is aluminum or an aluminum alloy, when the reflective film is aluminum or an aluminum alloy in which the vicinity of the substrate interface is oxidized, a higher adhesion improving effect can be obtained. It is possible to form a reflective film having a larger film thickness with better adhesiveness than in the case where the film is formed, and the film to be formed can be appropriately selected according to the thickness of the film required as the reflective film. it can.

When using the above-mentioned multilayer structure reflection film,
Even with a two-layer structure of an aluminum or aluminum alloy oxide film and an aluminum or aluminum alloy film,
It may have a multi-layered structure in which the metal composition of these two kinds is continuously changed.

The thickness of the oxide film of aluminum or aluminum alloy is usually about 50 to 150 angstroms.

In the present invention, as a method of forming an aluminum or aluminum alloy oxide film, a method of forming a film using a target made of an aluminum oxide film or an aluminum alloy oxide film, a target made of aluminum or an aluminum alloy, Examples include a method of forming an aluminum oxide film or an aluminum alloy oxide film during film formation.

In the present invention, as the acrylic resin substrate, a known resin substrate obtained from a monomer containing a (meth) acrylic acid ester is used, and examples thereof include methyl methacrylate, ethyl methacrylate, propyl methacrylate. (Co) polymers of methacrylic acid esters such as methacrylic acid esters such as cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, norbornyl methacrylate, norbornyl methyl methacrylate and isobornyl methacrylate, or acrylic acid with these. Acrylic acid esters such as methyl, ethyl acrylate, propyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, norbornyl acrylate, norbornyl methyl acrylate, isonorbornyl acrylate, N- Black hexyl maleimide, N- phenylmaleimide, N- chlorophenyl maleimide, N
Examples thereof include copolymers with acid anhydrides such as -methylphenylmaleimide and N-bromophenylmaleimide.

In particular, when the acrylic resin substrate is made of a polymer having a methacrylic acid ester monomer unit of 50 mol% or more, it is difficult to form a metal reflection film of aluminum or aluminum alloy having good adhesion by the conventional method. Due to the strong tendency, a significant improvement in adhesion is achieved.

Compared to the case where the film formed on the acrylic substrate is aluminum or an aluminum alloy, when the aluminum or aluminum alloy film in which the vicinity of the substrate interface is oxidized is used, the acrylic substrate has a methacrylic acid ester monomer unit of 50 mol%. Of course, when the acrylic substrate is made of the above-mentioned polymer, the acrylic substrate is particularly a methacrylic acid ester monomer unit 8
When it is composed of 0 mol% or more of the polymer, a more remarkable effect of improving the adhesiveness can be obtained.

[0026]

EXAMPLES The present invention will be specifically described with reference to the following examples.

Example 1 As shown in FIG. 1, on an injection-molded substrate obtained by using a copolymer consisting of 90% by weight of methyl methacrylate and 10% by weight of methyl acrylate,
With a sputtering device (basic specifications: SBH-2304, manufactured by Nippon Vacuum Technology Co., Ltd.) provided with an anode electrode having a potential of 80 V between the substrate holder and the target, argon gas was introduced into the vacuum chamber to obtain φ4. A direct current voltage was applied to the aluminum target to form an aluminum film having a film thickness of 500 angstrom at a film forming rate of 1100 angstrom / min.

When the following peeling test was carried out to evaluate the adhesiveness of the obtained metal film, the aluminum film was not peeled at all and the adhesiveness was good.

<Peel Test> The adhesive surface of an adhesive tape (Nichiban Co., Ltd .: “Cellotape” used) was brought into close contact with the aluminum film, and was peeled off vigorously to evaluate the level of peelability.

<Embodiment 2> The same as Embodiment 1 except that the sputtering apparatus is used as shown in FIG. 2 in which an acrylic resin substrate is fitted in a conductive supporting frame material, instead of providing an auxiliary electrode. When an aluminum film was formed on the substrate and the adhesion was evaluated, the aluminum film was not peeled at all, and the adhesion was good.

<Example 3> On the same injection-molded substrate as in Example 1, the same sputtering apparatus as in Example 1 was used.
Argon gas was introduced into the empty tank, a high frequency (13.56 MHz) was applied to a φ4 ″ alumina target, and a film formation rate was 70 Å / min, and an alumina (aluminum oxide) thin film was 50 Å as the first layer.
A DC voltage was applied to a 4 ″ aluminum target, a 900 Å aluminum film was sequentially formed as a second layer at a film formation rate of 1100 Å / min, and a metal film having a total film thickness of 950 Å was formed on the substrate to provide adhesion. When the evaluation was made, the laminated film was not peeled at all, and the adhesion was good.

<Example 4> Methyl methacrylate monomer 4
8% by weight and cyclohexyl acrylate monomer 32% by weight
Example 1 except that an injection-molded substrate of a copolymer consisting of 20% by weight of N-cyclohexylmaleimide monomer and an aluminum film thickness of 900 Å was used.
A film was formed in the same manner as in, and the adhesion was evaluated. As a result, the aluminum film was not peeled at all, and the adhesion was good.

Comparative Example 1 A metal film having the same thickness as in Example 1 was formed on the substrate in the same manner as in Example 1 except that the auxiliary electrode was not provided, and the adhesion was evaluated. Most of the aluminum film was peeled off.

Comparative Example 2 An aluminum film having the same thickness as in Example 2 was formed on a substrate in the same manner as in Example 2 except that the conductive supporting frame material was not used, and the adhesion was evaluated. At this point, most of the aluminum film was peeled off.

Comparative Example 3 A laminated film having the same thickness as in Example 3 was formed on the substrate in the same manner as in Example 3 except that the auxiliary electrode was not provided, and the adhesion was evaluated. The film has largely peeled off.

[0036]

As described above in detail, the optical disk obtained by the present invention has a reflective film of aluminum or aluminum alloy excellent in adhesion by a sputtering method even if a methacrylic resin substrate is used. Yes, compared to the conventional vacuum deposition method, in-line is possible,
The production cost can be reduced because the space required for the device is reduced, and the effect is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an embodiment of a sputtering apparatus provided with an auxiliary electrode used in the present invention.

FIG. 2 is a schematic vertical cross-sectional view of one embodiment of a sputtering apparatus provided with a conductive support frame material used in the present invention.

[Explanation of symbols]

 1: Gas introduction port 2: Vacuum tank 3: Substrate holder 4: Target 5: Auxiliary electrode 6: Substrate 7: Cathode 8: Exhaust port 9: Power source 10: Power source 11: Conductive support frame material

Claims (3)

[Claims] 1. A sputtering device in which a ring-shaped auxiliary electrode is provided between a substrate holder and a target, or a ring shape having a shape in contact with the entire side surface of the substrate on the substrate holder and having a thickness higher than the thickness of the substrate. An optical disc having a metal reflection film of aluminum or aluminum alloy formed on an acrylic resin substrate by a sputtering device provided with the conductive support frame material. 2. The multi-layer structure film, wherein the reflective film formed on the acrylic resin substrate is aluminum or an aluminum alloy in which at least the interface between the reflective film and the substrate is oxidized. Optical disc. 3. The optical disk according to claim 1, wherein the acrylic resin substrate is made of a polymer having a methacrylic acid ester monomer ratio of 50 mol% or more.