JPS62119757A - Optical recording medium - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of the titled medium without deteriorating the characteristic as a recording medium by forming a film consisting of the sulfide of at least one substance among calcium, magnesium, manganese, zirconium, and aluminum on the optical recording layer. CONSTITUTION:The film consisting of the sulfide of at least one substance among calcium, magnesium, manganese, zircinium, and aluminum is formed on one or both sides of the optical recording layer. Although every sulfide film is formed by vapor deposition, electron beam vapor deposition is especially appropriate. When glass is used for the substrate, an UV curing resin (2p) layer, etc., is formed between the sulfide film and the glass sheet with the object of forming an optical guide groove. When the sulfide film is formed in succession to the optical recording layer, a recording layer is formed by vapor deposition, sputtering, etc., and then a sulfide film is successively formed without turning off the vacuum.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical recording medium on which recording and reproduction can be performed using a light beam.

[Prior Art] Conventionally, optical recording media used in optical discs include rare earth-transition metal alloy thin films, reduction of chalcogen compounds, etc. that utilize phase transition from amorphous to crystalline, and oxide thin films. , heat mode recording media, thermoplastic recording media, etc. 0For example, MnB is a magneto-optical recording medium formed of a rare earth-transition metal alloy thin film.
1°MnCuB1. tcj which polycrystalline thin film, GdCo.

GdFe, TbFe, DyFe, GdTbFe.

Amorphous thin films such as TbDyFe and single crystal thin films such as GdIG are known.

Among these thin films, the film forming efficiency when manufacturing a large-area thin film at a temperature near room temperature, the writing efficiency for writing a signal even with small photothermal energy, and the write signal S
Considering readout efficiency etc. to read out with good /N ratio,
Recently, the amorphous thin film is considered to be excellent as a photothermal magnetic recording medium. 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, 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.

[Problem that the invention seeks to solve]

However, amorphous magnetic materials generally used in magnetic recording media, including magneto-optical recording media such as GdTbFe, have a drawback of poor corrosion resistance. That is, when it comes into contact with the atmosphere or water vapor, it becomes oxidized and becomes transparent. Furthermore, this problem is common not only to magneto-optical recording media but also to the optical recording media described above.

In order to eliminate such drawbacks, conventionally, a protective cover made of, for example, a transparent material, such as SiO2, Si
Disc-shaped recording media with an air sandwich structure or a laminated structure in which a protective layer of O is provided or the recording layer is roughly sealed with an inert gas have been proposed, but they have not been able to provide sufficient corrosion resistance for practical use.

The present invention has been made in view of the above problems, and an object thereof is to provide an optical recording medium with improved corrosion resistance without impairing the characteristics of the recording medium.

[Means for solving problems]

The above object of the present invention is to provide an optical recording medium having an optical recording layer on a substrate, in which at least one of calcium, magnesium, manganese, zirconium, and aluminum is added to one or both sides of the optical recording layer. This is achieved by using an optical recording medium formed with a film made of sulfides of two substances.

That is, the present invention provides an optical recording medium using calcium sulfide, magnesium sulfide, mankan sulfide, zirconium sulfide, and aluminum sulfide, which have a greater effect of preventing oxidation of the optical recording layer than 510z and SiO.

The above-mentioned sulfide films can be formed by any vapor deposition method, but electron beam vapor deposition is particularly suitable.

When glass is used for the substrate, an ultraviolet curing resin (2P) layer or the like is provided between the oxide film and the glass plate for the purpose of forming optical guide grooves.

In the present invention, when forming a sulfide film subsequent to the optical recording layer, it is desirable to form the sulfide film continuously without breaking the vacuum after forming the recording layer by a method such as vapor deposition or sputtering. .

Furthermore, when forming a sulfide film on a substrate, forming an optical recording layer thereon, and then forming a sulfide film, it is better to form the films continuously in the same bath without breaking the vacuum.

(Example) Hereinafter, the present invention will be described in more detail with reference to Examples. However, the present invention is not limited to the following Examples, and various applications are possible. For example, the optical recording layer Not only records,
Any optical recording material may be used, as mentioned in the description of the prior art, and the optical recording medium constructed according to the present invention may be of a well-known air sandwich structure or of glass. Corrosion resistance can be further improved by creating a structure in which it is laminated with a plate or the like.

Example 1 In an RF sputtering device, a 1-inch square white plate glass was used as a substrate, and a 100 mm thick iron-cobalt alloy (Fe7.
Co 3) GdT was sputtered using a composite target of 5 mm square small pieces of gadolinium terbium alloy (Gd5.Tb) evenly arranged on a plate.
1000mm thick made of bFeCo quaternary amorphous magnetic film
Formed a human optical recording layer. Subsequently, after evacuation to about 2 x 10-' Pa in a normal vacuum evaporation apparatus, calcium sulfide (CaS) was evaporated using an electron beam evaporation source, and a calcium sulfide film with a thickness of 2000 nm was evaporated on the recording layer. did.

Example 2 In a normal vacuum evaporation apparatus, a substrate in which an ultraviolet curable resin (2P) (epoxy acrylate) layer (10 to 100 μm) was formed on the glass plate of Example 1 was heated 2× in a vacuum chamber.
After evacuation to about 10-' Pa, calcium sulfide (CaS) was evaporated using an electron beam evaporation source to deposit a calcium sulfide film with a thickness of 200 mm. On top of that, the same Fe, Go
A recording layer with a thickness of 1000 layers was formed by sputtering using a composite target of , Gd, and Tb. Calcium sulfide (C
aS) A calcium sulfide film having a thickness of 2000 nm was deposited on the recording layer by evaporating lFr.

Examples 3 to 10 Optical recording media were prepared in which protective Si consisting of magnesium sulfide, manganese sulfide, zirconium sulfide, and aluminum sulfide was provided in place of calcium sulfide in Example 1.2. The recording layer is GdTbFeC with a thickness of 1000 nm.
All sulfide films were formed by electron beam evaporation using a quaternary amorphous magnetic film of 0.

Example 11 In a normal vacuum evaporation device, the inside of the vacuum chamber is 2×10″P.
After evacuation to approximately 100 m², calcium sulfide (CaS) was evaporated onto a 1 square inch polymethyl methacrylate (PMMA) substrate using an electron beam evaporation source to deposit a calcium sulfide film with a thickness of 200 mm. On top of that, the same Gd, Tb, F as in Example 1 was subsequently applied in an RF sputtering apparatus.
A recording layer having a thickness of 1000 layers was formed by sputtering using a composite Couget of E and Go. After evacuation was approximately 2×10 −′ Pa in a conventional vacuum evaporation apparatus, calcium sulfide (CaS) was evaporated using an electron beam evaporation source to deposit a calcium sulfide film with a thickness of 2000 μm on the recording layer.

Example 12 In a normal vacuum evaporation device, the inside of the vacuum chamber is 2×10″P.
After evacuation to a degree, 1 inch square polycarbonate (PC)
Calcium sulfide (C:
aS) was evaporated to deposit a calcium sulfide film with a thickness of 200 mm. On top of that, the same Gd as in Example 1 was applied in an RF sputtering apparatus.

Spackling was performed using a composite target of Tb, Fe, and Go to form a recording layer with a thickness of 1,000 layers.

Furthermore, in a normal vacuum evaporation apparatus, after evacuation to about 2 x 10@Pa, calcium sulfide (C
aS) was evaporated, and a calcium sulfide film having a thickness of 2000 Å was deposited on the recording layer.

Examples 13 to 20 Optical recording media were prepared by replacing the calcium sulfide in Examples 11 and 12 with protective films made of magnesium sulfide, manganese sulfide, zirconium sulfide, and aluminum sulfide, respectively. The recording layer is GdTb with a thickness of 1000 nm.
A quaternary amorphous magnetic film of FeCo was used, and all sulfide films were formed by electron beam evaporation.

Example 21 In an RF sputtering apparatus, a 1-inch square white plate glass was used as a substrate, and the same Gd as in Example 1 was used.

A recording layer with a thickness of 200 nm was formed by sputtering using a composite target of Tb, Fe, and Go. Next, after evacuation of about 2 × 10 → Pa in a normal vacuum evaporation equipment,
Calcium sulfide (CaS) was evaporated using an electron beam evaporation source, and a calcium sulfide film having a thickness of 1000 nm was deposited on the recording layer. Roughly, 500 people formed an AI film as a reflective film on this, and finally, 2000 people deposited a protective film made of calcium sulfide on top of this.

Example 22 In a normal vacuum evaporation apparatus, a 2×10 vacuum chamber was placed on the same glass plate as in Example 2, on which an ultraviolet curable resin (2P) (epoxy acrylate) layer (10 to +0OU) was formed. -' Pa After evacuation, calcium sulfide (CaS) is evaporated by an electron beam evaporation source to a thickness of 20
0 calcium sulfide films were deposited.

Subsequently, Example 1 was prepared in an RF sputtering apparatus.
Sputtering was performed using the same composite target of Gd, Tb, Fe, and Go to form a recording layer with a thickness of 200 nm. Then, 2× in a normal vacuum evaporation equipment
After evacuation to about 10→Pa, calcium sulfide (CaS) is evaporated using an electron beam evaporation source to form a layer with a thickness of +
A 000A calcium sulfide film was deposited. Roughly 500 layers of A111 were formed on this as a reflective film, and finally, 200 layers of a protective film made of calcium sulfide was deposited on top of this.

Example 23-v30 Optical recording media were prepared in which protective films were formed of magnesium sulfide, manganese sulfide, zirconium sulfide, and aluminum sulfide in place of calcium sulfide in Examples 21 and 22. The recording layer is GdTbFe with a thickness of 200 mm.
A quaternary amorphous magnetic film of Co was used, and all sulfide films were formed by electron beam evaporation.

Example 31 In a normal vacuum evaporation apparatus, the inside of the vacuum chamber is 2×10=P
After evacuation to a depth of approximately 200 mm, calcium sulfide (CaS) was evaporated onto a 1 inch square polymethyl methacrylate (PMMA) substrate using an electron beam evaporation source to deposit a 200 mm thick calcium sulfide film. On top of that, the same Gd, Tb, F as in Example 1 was subsequently applied in an RF sputtering device.
A recording layer with a thickness of 200 mm was formed by sputtering using a composite target of e. Subsequently, after evacuation of approximately 2×10″4 Pa in a normal vacuum evaporation apparatus, calcium sulfide (CaS) was evaporated using an electron beam evaporation source, and a calcium sulfide film with a thickness of 1000 μm was evaporated on the recording layer. On top of this, a 500% Al film is applied as a reflective film.
Finally, a protective film made of calcium sulfide was deposited on top of the 2,000-layer film.

Example 32 In a normal vacuum evaporation apparatus, the inside of the vacuum chamber is 2×10″P.
After evacuation to a degree, 1 inch square polycarbonate (PC)
Calcium sulfide (Ca) is deposited on the substrate using an electron beam evaporation source.
b) was evaporated to deposit a 200 mm thick calcium sulfide film. On top of that, the same Fe as in Example 1 was subsequently applied in an RF sputtering apparatus.

Sputtering was performed using a composite target of Gd and Tb to form a recording layer with a thickness of 200 mm. Next, the vacuum was evacuated to about 2 x 1O-4Pa in a normal vacuum evaporation equipment.
Calcium sulfide (CaS)% by electron beam evaporation source
After evaporation, a calcium sulfide film to a thickness of +000 was deposited on the recording layer. On top of this, Al is applied as an anti-IH film.
A protective film made of calcium sulfide was deposited on top of this layer by 2,000 people.

Examples 33 to 40 Optical recording media were prepared in which protective films made of magnesium sulfide, manganese sulfide, zirconium sulfide, and aluminum sulfide were provided in place of calcium sulfide in Examples 31 and -32. The optical recording layer is GdT with a thickness of 200A.
A quaternary amorphous magnetic film of bFeCo was used, and all sulfide films were formed by electron beam evaporation. An optical recording medium was prepared in the same manner as in Example 1.

Comparative Example 2 Example 7 except that 2000 CaSRs were not established
An optical recording medium was prepared in the same manner as above.

Comparative Example 3 An optical recording medium was produced in the same manner as in Example 21 except that SiO was used instead of CaS.

Comparative Example 4 An optical recording medium was produced in the same manner as in Example 21 except that the protective layer and reflective layer were not provided.

Corrosion Resistance Test A corrosion resistance test was conducted by placing the optical recording media prepared according to Examples 1 to 40 and Comparative Examples 1 to 4 described above in a constant temperature and humidity chamber at 70° C. and 85% RH. Examples 1 and 21
and the results of Comparative Examples 1 to 4 are shown in tM1 diagram and Figure 2. In Figures 1 and 2, the horizontal axis is the test time [unit is time (
H)], and the vertical axis shows the change in coercive force Hc as a ratio of the coercive force to the initial value Hco. Here, the more the coercive force decreases, the more corrosion progresses.
The results of Example 1 were almost the same as those of Example 1, and the results of Examples 22 to 40 were (very similar) to Example 21.

As can be seen from Figures 1 and 2, calcium sulfide,
Magnesium sulfide, manganese sulfide, zirconium sulfide,
The use of aluminum sulfide as a protective layer can improve the corrosion resistance of optical recording media.

〔Effect of the invention〕

According to the present invention, an optical recording medium with excellent corrosion resistance was obtained.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing the results of a corrosion resistance test of an optical recording medium based on the present invention, respectively. 1: Coercive force curve of Example 1 2: Coercive force curve of Comparative example 1 3: Coercive force curve of Comparative example 2 4: Coercive force curve of Example 21 5: Coercive force curve of Comparative example 3 6: Comparative example Coercive force curve of 4

Claims (1)

[Claims] In an optical recording medium comprising an optical recording layer on a substrate, calcium is provided on one or both sides of the optical recording layer.
An optical recording medium comprising a film formed of a sulfide of at least one substance selected from magnesium, manganese, zirconium, and aluminum.