JPH04328344A - Magneto-optical recording disk - Google Patents

Abstract

PURPOSE:To provide the magneto-optical recording disk which is excellent in both of productivity and environmental resistance. CONSTITUTION:The protective layer 4 of the magneto-optical recording disk provided with a dielectric layer 2, a recording layer 3 and a protective layer 4 in this order from a substrate 1 side on a substrate 1 is formed of any of a metallic film, metallic oxide and metallic nitride film contg. metallic elements similar to at least one kind among the metallic elements incorporated into the recording layer 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording disk, and more particularly to a magneto-optical recording disk with excellent productivity and environmental resistance.

0002

2. Description of the Related Art For example, as shown in FIG.
A dielectric layer 101, a recording layer 102, and a dielectric protective layer 10 are provided on top.
A so-called magneto-optical recording disk having a so-called three-layer film structure in which 3 layers are provided in this order is known. In the magneto-optical recording disk having such a configuration, the dielectric layer 101 has both the function of a Kerr effect enhancement film and the function of a protective film for the recording layer, and is made of, for example, a ZnS film, a SiN film, an AlN film, a SiO film, or a SiO film.
It was formed from a dielectric film such as an O2 film. Further, the recording layer 102 was formed of, for example, a TbFeCo film. The dielectric protective layer 103 provided for the purpose of protecting the recording layer 102 is usually a ZnS film, an S
It was formed of a dielectric film similar to the dielectric layer described above, such as an iN film. In addition, in FIG. 4, 110 is a resin protective film.

0003

[Problems to be Solved by the Invention] However, in the conventional magneto-optical recording disk having a so-called three-layer film structure as described above, a dielectric film such as a ZnS film, which forms a dielectric protective layer, is formed by sputtering. If you increase the output when doing this, the target will break, so you cannot increase the output, and therefore it takes a long time to form the film.
There was a problem with poor productivity.

Furthermore, since the physical properties of a dielectric protective layer made of a ZnS film or the like are significantly different from those of a recording layer made of a TbFeCo film or the like, the dielectric protective layer does not have a sufficient protective effect on the recording layer, especially in a high temperature and high humidity environment. There was also a problem that the environmental resistance was not sufficient. The present invention has been made based on such circumstances, and an object of the present invention is to provide a magneto-optical recording disk with excellent productivity and environmental resistance.

[0005]

[Means for Solving the Problems] The gist of the present invention to achieve the above object is to provide a magneto-optical recording disk in which a dielectric layer, a recording layer, and a protective layer are provided on a substrate in this order from the substrate side. , the protective layer is formed of one of a metal film, a metal oxide film, and a metal nitride film containing at least one metal element similar to the metal element contained in the recording layer; This is a special magneto-optical recording disk.

[0006]

[Operation] In the magneto-optical recording disk of the present invention, the protective layer formed on the recording layer provided on the dielectric layer formed on the substrate protects the metal element contained in the recording layer. It is formed of a metal film, a metal oxide film, or a metal nitride film containing at least one of the same metal elements. The deposition rate of the metal film, metal oxide film, and metal nitride film that form such a protective layer is the same as that of a dielectric film such as a ZnS film that forms a dielectric protective layer in a conventional magneto-optical recording disk. Since it is faster than the film speed, the film formation time is shortened. Therefore, the magneto-optical recording disk of the present invention has superior productivity compared to the conventional magneto-optical recording disk having a so-called three-layer structure. In addition, such a protective layer can be formed continuously with the recording layer, and there is no clear interface between the protective layer and the recording layer.
Since its physical properties are similar to those of the recording layer, the protective layer can sufficiently protect the recording layer even in a high temperature and humidity environment. Therefore, the magneto-optical recording disk of the present invention has excellent environmental resistance.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the layer structure of the magneto-optical recording disk of the present invention. As shown in FIG. 1, this magneto-optical recording disk has a dielectric layer 2, a recording layer 3, and a protective layer 4 provided in this order on a substrate 1 having optical transparency. A protective film 5 made of resin is formed.

[0008] The material for forming the substrate 1 may be any material as long as it has light transmittance, such as light transmitting glass or light transmitting resin such as polycarbonate resin (PC) or acrylic resin. It will be done. The thickness of such a substrate 1 is usually about 0.5 to 1.5 mm. The dielectric layer 2 provided on the substrate 1 is made of, for example, ZnS.
, SiN, AlN, SiO, SiO2, or other dielectric material. The thickness of such dielectric layer 2 is usually about 40 to 100 nm.

The recording layer 3 formed on the dielectric layer 2 is made of, for example, TbFeCo, GaTbCo, Gd
FeBi, DyFe, GdFe, GdCo, BiSmY
bCoGeIG, BiSmErGaIG, GdIG, C
oCr, CrO2, PtCo, EuOFe, EuO,
It is formed from a magneto-optical recording material such as MnCuBi, MnAlGe, or MnBi. Among these magneto-optical recording materials, TbFeCo is particularly preferred. Recording layer 3
The thickness is usually about 20 to 90 nm.

A metal film, a metal oxide film, or a metal nitride film containing at least one of the same metal elements contained in the recording layer 3 is formed on the recording layer 3. A protective layer 4 is provided. Examples of materials for forming such a protective layer 4 include terbium (Tb), gadolinium (Gd), dysprosium (Dy), and europium (among metal elements similar to those contained in the recording layer 3). Eu), erbium (Er), samarium (Sm), ytterbium (Yb
); Rare earth elements such as aluminum (Al), cobalt (
Metals that cause passivation such as Co) are preferred, and terbium (Tb) is particularly preferred. Further, the protective layer 4 may be formed of oxides or nitrides of these metals. Note that when the recording layer 3 contains two or more kinds of rare earth elements, at least one of them may be used as the material for forming the protective layer 4.

The thickness of such a protective layer 4 is usually 20 mm.
~100mm. A resin protective film 5 is usually formed on the protective layer 4 using, for example, an ultraviolet curing resin. This resin protective film 5 usually covers not only the upper flat surface 4a of the protective layer 4 but also the dielectric layer 2, as shown in FIG.
, it is preferable to also cover the entire side surfaces of the recording layer 3 and the protective layer 4. This prevents corrosion from the sides of the dielectric layer 2, recording layer 3, and protective layer 4. The thickness of such a resin protective film 5 is usually about 0.5 to 50 μm.

Next, an example of manufacturing the magneto-optical recording disk of the present invention will be explained based on FIG. 2. Here, a sputtering method is used as the vacuum film forming method. First, a disk-shaped substrate 1 is fixed to a substrate holder 20 in a bell jar (not shown) of a vacuum film forming apparatus. Next, a ring-shaped mask 30 is placed on the periphery of this disk-shaped substrate 1, and then the substrate 1 is exposed using the dielectric material as a target.
A dielectric layer 2 is deposited on top. At this time, the inert gas pressure (sputtering pressure) as a sputtering condition is 1 Pa or less,
In particular, it is preferable to set it as 0.04-0.7Pa. Inert gases include argon (Ar), helium (He
), krypton (Kr), etc., but usually argon (Ar) is preferably used in consideration of economic efficiency.

Next, a recording layer 3 is formed on this dielectric layer 2 by sputtering. At this time, the inert gas pressure as a sputtering condition is about 0.1 to 0.7 Pa. Next, a protective layer 4 is formed on this recording layer 3 by sputtering. In this case, the inert gas pressure (for example, argon gas pressure) as a sputtering condition is usually about 0.1 to 3 Pa, preferably about 0.5 to 1 Pa.

[0014] Other conditions for forming the above three types of films are a power of about 100 to 1500 W;
Target voltage is about 0.2 to 1.0 kW, target spacing is about 100 to 300 mm, and target diameter is 130 mm.
~200 mm or so, and the substrate temperature is approximately 20~100°C. After completing such a sputter film formation process, the substrate 1
The dielectric layer 2, the recording layer 3, and the protective layer 4 formed in this order on top are carried out from the bell jar, and then the mask is removed, and the upper flat surface of the protective layer 4, the protective layer 4, and the recording layer are removed. 3 and the entire side surface of the dielectric layer 2 are coated with a resin such as an ultraviolet curable resin to form a resin protective film 5.

The present invention will be explained in more detail below based on specific experimental examples. Experimental example-1 A substrate holder with a diameter of 30 cm is placed inside the bell jar of a vacuum film deposition system.
, a disk-shaped glass substrate with a thickness of 1.2 mm was fixed. Next, an outer diameter of 45c is placed on the periphery of this disk-shaped substrate.
m, and a mask with an inner diameter of 29.5 cm was placed.

Next, a dielectric layer was formed to a thickness of 85 nm by sputtering using ZnS as a target as a dielectric material. At this time, the inert gas pressure (sputtering pressure) is 0.
The pressure was 7 Pa, and argon (Ar) was used as the inert gas. Thereafter, a recording layer made of a TbFeCo film was formed to a thickness of 60 nm on this dielectric layer by sputtering. At this time, the inert gas pressure (argon gas pressure) is 0.5 Pa.
And so.

Subsequently, terbium (T) is deposited on this recording layer.
A protective layer consisting of b) was formed to a thickness of 50 nm continuously with the formation of the recording layer by sputtering. That is, in sputtering using Tb and FeCo as targets, only the Tb shutter was opened and the FeCo shutter was closed, thereby forming the recording layer and the protective layer continuously.

Thereafter, the dielectric layer, the recording layer, and the protective layer formed in this order on the disk-shaped substrate as described above are taken out of the bell jar, and the upper flat surface of the protective layer, the protective layer, and the recording layer are removed. Then, apply ultraviolet curable resin to the entire side surface of the dielectric layer by spin coating to a thickness of 0.0
A 5 mm resin protective film was formed. When the obtained magneto-optical recording disk was subjected to an accelerated environmental resistance test under the conditions of a temperature of 80° C. and a humidity of 90%, the results shown in FIG. 3 were obtained. Experimental Example 2 After sequentially forming a dielectric layer and a recording layer on a substrate in the same manner as in Experimental Example 1, nitrogen (N2 ) A protective layer consisting of a Tb nitride film having a thickness of 50 nm was formed by supplying gas and performing reactive sputtering using Tb as a target. Thereafter, a magneto-optical recording disk was produced in the same manner as in Experimental Example 1. Experimental Example 3 After sequentially forming a dielectric layer and a recording layer on a substrate in the same manner as in Experimental Example 1, oxygen (O2 ) A protective layer consisting of a Tb oxide film having a thickness of 50 nm was formed by supplying a gas and performing reactive sputtering using Tb as a target. Thereafter, a magneto-optical recording disk was produced in the same manner as in Experimental Example 1. Comparative Experimental Example 1 After sequentially forming a dielectric layer and a recording layer on a substrate in the same manner as in Experimental Example 1, a sputtering method using ZnS as a target was performed to form a dielectric layer made of a ZnS film with a thickness of 50 nm. A body protection layer was deposited. At this time, it took approximately three times as long to form the ZnS film as the time required to form the Tb film in Experimental Example 1. Thereafter, a magneto-optical recording disk was produced in the same manner as in Experimental Example 1.

When the obtained magneto-optical recording disk was subjected to an accelerated environment resistance test under the same conditions as in Experimental Example 1, the results shown by ● in FIG. 3 were obtained. Consideration of Experimental Examples From the above experimental examples, the time for forming the protective layer on the magneto-optical recording disk of the present invention was reduced to about 1/3 compared to the conventional magneto-optical recording disk produced in Comparative Experimental Example 1. It was confirmed that productivity was greatly improved and environmental resistance was also improved.

[0020]

[Effects of the Invention] According to the present invention, with the above structure, the time for forming the protective layer is greatly shortened, and productivity is significantly improved, and environmental resistance is also improved, resulting in increased productivity. A magneto-optical recording disk having excellent environmental resistance and environmental resistance is provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a magneto-optical recording disk of the present invention.

FIG. 2 is an explanatory cross-sectional view showing an example of a state during the manufacturing process of the magneto-optical recording disk of the present invention.

FIG. 3 is a graph showing test results of accelerated environmental resistance tests for the magneto-optical recording disk of the present invention and the conventional magneto-optical recording disk.

FIG. 4 is a cross-sectional view showing an example of a conventional magneto-optical recording disk.

[Explanation of symbols]

1...Substrate 2...Dielectric layer 3...Recording layer 4...Protective layer

Claims (1)

[Claims] 1. In a magneto-optical recording disk in which a dielectric layer, a recording layer, and a protective layer are provided on a substrate in this order from the substrate side, the protective layer comprises one of the metal elements contained in the recording layer. 1. A magneto-optical recording disk characterized in that it is formed of any one of a metal film, a metal oxide film, and a metal nitride film containing at least one of the same metal elements.