JPH0469832A - magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve the mechanical strength, durability and recording density of the medium by using an amorphous dielectric film having specified refractive index. CONSTITUTION:The dielectric film 2 and/or 4 is formed from an amorphous material containing H. This film is formed by sputtering a target such as amorphous Si:H film, amorphous SiGe:H film, amorphous SiN:H film, with using a HF power source in a gas atmosphere of H2 and SiH4, GeH4, N2, NH3, etc., in the vacuum device according to the kind of the film to be formed. If the refractive index of the dielectric film is <1.75, enhancing effect caused by multireflection of light on the medium surface is not expected, while with >3.20 refractive index, the film property decreases which adversely affects the mechanical strength and durability. Thereby, the refractive index is specified to 1.75 - 3.20.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magneto-optical recording medium, particularly a magneto-optical recording medium which has excellent chemical stability, excellent optical transparency, good C/N, and improved recording density. This invention relates to a magneto-optical recording medium that can measure

[Prior Art] In recent years, with the advancement of the information society, rewritable magneto-optical memory has attracted attention, and rare earth element-transition metal element thin films such as TbFeCo are used as magnetic films for this magneto-optical memory. However, this method has the disadvantage that the obtained Kerr rotation angle is not very large and the C/N of the reproduced signal is not sufficient.

[Problems to be Solved by the Invention] Therefore, in this type of magneto-optical recording medium, the surface of a conventionally known amorphous magnetic film is coated with Sin or SiN.

A dielectric layer (film) such as AfN is formed, and its thickness is set to λ/
4n (λ is the laser wavelength, n is the refractive index) to increase the apparent Kerr rotation angle and increase the C/N (enhancement effect), but the improvement in characteristics by this is still unresolved. There is a need for a dielectric layer with even higher refractive index and better transparency.

Recently, as the demand for higher speed signal processing has become stronger for magneto-optical recording media, the recording density of the disk has become a major issue.In order to increase the recording density, the thermal conductivity of the dielectric film has been increased. Attempts have been made to reduce the power required for recording by suppressing thermal diffusion and increasing the thermal efficiency of lasers, but the conventionally used S
It is difficult to keep thermal conductivity low with dielectric films using EN, AflN, SiO, etc., and from this point of view as well, the development of new film materials is required.

On the other hand, conventionally used amorphous magnetic films contain rare earth metals, but because these rare earth metals are extremely easily oxidized, their magnetic properties easily deteriorate under high temperature and high humidity conditions. There is a problem that S
Oxides such as iO, on the other hand, do not have a sufficient effect because the rare earth elements cause an oxidation reaction with 0 in SiO, while nitrides such as SiN and Ai'N have such reactivity. Although it can be used for the purpose of improving corrosion resistance because of its small size, cracks are likely to occur when forming a film on a resin substrate or the like, and there are problems with mechanical strength.

[Means for Solving the Problems] The present invention relates to a magneto-optical recording medium that can solve the above problems, and includes a dielectric layer and a magnetic film on a transparent substrate placed on the light incident side. , a magneto-optical recording medium provided with a reflective film, characterized in that the dielectric layer is made of an amorphous material containing H.

In other words, the present inventors found that the C/N
As a result of various studies aimed at developing a magneto-optical recording medium with improved recording density and improved recording density, we found that H
When using an amorphous material containing , the recording sensitivity can be improved, 2) If the film material contains H, thermal diffusion is reduced, so the expansion of the recording bit diameter can be suppressed, and the recording density can be improved. 3) The film If the raw material contains H, it tends to become amorphous, and a smooth film with excellent compositional uniformity can be obtained. 4) This film is more difficult to peel than conventional protective films; It has excellent mechanical strength and durability, so it is useful for protecting the recording film.
) This material has a large refractive index, so it has a large enhancement effect, and it also has excellent light transmittance, especially in the visible to far infrared region, so the C/N
The inventors discovered that it was possible to obtain a magneto-optical recording medium with a large amount of hydrogen, and conducted research on methods for forming the amorphous material containing H used therein, and completed the present invention.

This will be explained in further detail below.

[Function] The magneto-optical recording medium of the present invention is a magneto-optical recording medium in which a dielectric layer, a magnetic film, and a reflective film are provided on a transparent substrate, in which the dielectric layer is made of an amorphous material containing H. .

The structure of this magneto-optical recording medium is known, and as shown in FIG. A dielectric film 2, a magnetic film 3, a dielectric film 4 of the same quality as the dielectric film 2, and a reflective film 5 are sequentially laminated on a substrate 1, and as shown in FIG. It may have a three-layer structure in which a dielectric layer 8, a magnetic film 9, and a dielectric layer 1i10 are sequentially laminated on top of the transparent substrate 1.7. When incident, the light 6 is reflected by the reflection 115, and in the case of the one shown in FIG. 2 in which the thickness of the magnetic film is increased, the incident light 11 is reflected by the magnetic film 9.

In the magneto-optical recording medium of the present invention, the dielectric film 2.8 and/or 4.10 is formed of the above-mentioned amorphous material containing H. is amorphous Si:H film, amorphous 5iGe:Hw
A, an amorphous SiN:H film, etc. are exemplified. The formation of this dielectric film uses Si, 5iGe,
H2, 5iH4GeH4, N2 depending on the type of film forming inside the vacuum device using SiN etc. and using a high frequency power supply.
．． Sputtering may be performed in a gas atmosphere such as N)h.

The dielectric film thus obtained has a thickness of 500 to 1.00 mm.
However, if the refractive index is less than 1.75, an apparent increase in θ3 (enhancement effect) due to multiple reflections of light on the medium surface cannot be expected;
If you try to make it larger, the film quality will deteriorate and mechanical strength and durability will be adversely affected, so the refractive index (n) should be 1.
It is desirable to set it as the thing of 75-3.20.

Incidentally, in the magneto-optical recording medium of the present invention, a magnetic film and a reflective film are formed on the dielectric film formed on the substrate, and both of these may be of known type. consisting of a rare earth element-transition metal element film, therefore T
b, Rare earth elements such as Dy, Gd, and Nd and Fe,
Made of metal elements such as Go and Ni, for example, T
bFe, TbFeCo, GdDybFe, GdDy
An amorphous metal film made of FeCo or the like with the structure shown in Figure 1 requires 200 to 500 people, and with the structure shown in Figure 2 it requires 80 people.
0~1,. It is sufficient to form the reflective layer by sputtering to a thickness of about 1,000 mm, and this reflective layer is made of Aρ, Cu, Au,
A metal film such as Ag may be provided with a thickness of about 200 to 1,000 layers.

[Example] Next, examples of the present invention and comparative examples will be given.

Examples 1-3. Comparative Examples 1-2 Amorphous 5ilH film, amorphous 5iGe・)1
8. An amorphous SiN:H film was created by sputtering, and Si, 5rGe, and SiN were placed as targets on a polycarbonate substrate, and argon gas was applied.
Amorphous Si:H film, amorphous 5iGe: )
750 people and 700 people for the film and amorphous SiN:H film, respectively.
The Tb
FaMi film, amorphous conductor film, aluminum reflective film, argon gas pressure 7@Torr, high frequency output 200
A magneto-optical recording medium was created by sputtering under the conditions of W, a magnetic film of 200 mm thickness, a dielectric film of 300 mm thickness, and a reflective film of 500 mm thickness, and each element forming the dielectric film was
When analyzed by BS and HFS and examined for its molar composition ratio, refractive index, and light transmittance, the results shown in Table 1 were obtained, and the hydrogen content and optimum recording power change in this magneto-optical recording medium were determined. When we investigated the relationship with the amount, we obtained the results shown in Figure 3. Also, 80℃,
When the durability at 85% RH was investigated, as shown in FIG. 4, it was found to have superior durability compared to commonly used SiN.

However, for comparison, the dielectric film was formed by sputtering in an argon gas atmosphere and was made of H-free Si, 5iGe, and SiNg, and the molar composition ratio, refractive index, and light transmittance of this film were As a result, the results shown in Table 1 were obtained, and when the recording sensitivity of this material was investigated, it was found that this material has a high thermal conductivity and a lower transmittance, so the recording sensitivity was lower than that of the above example. It was inferior.

[Effects of the Invention] The present invention relates to a magneto-optical recording medium, which is a magneto-optical recording medium in which a substrate is provided with an 8-electroelectric film, a magnetic film, and a reflective film, as described above, in which this electromagnetic material is formed by H. According to this method, this dielectric film has a refractive index of 1.75 to 3.20, which has a large enhancement effect, and also has a high light transmittance. In addition to increasing the C/N ratio, this amorphous film also has a smooth film surface because it contains H, which also has excellent mechanical strength and durability. Since the thermal conductivity is low, the thermal diffusion of the laser is small, which suppresses the expansion of the diameter of the recording bit, giving the advantage that the recording density is improved.

[Brief explanation of the drawing]

Figures 1 and 2 are block diagrams of magneto-optical recording media, Figure 3 is a graph of the relationship between the amount of hydrogen in the magneto-optical recording medium and the amount of change in optimum recording power in the example, and Figure 4 is a graph of the relationship between the retention time and the storage capacity. This is a graph showing the relationship with changes in magnetic force. 7 ・ ・ Transparent substrate 4.8.10... Dielectric film (layer) 3.9... Magnetic 11 [5... Reflective film WJ-voice 20 401 ~ Lateral H amount (at%) Third cause

Claims (1)

[Claims] 1. In a magneto-optical recording medium comprising a dielectric layer, a magnetic film, and a reflective film provided on a transparent substrate placed on the light incident side, the dielectric layer is an amorphous material containing H. A magneto-optical recording medium characterized by comprising: 2. The amorphous material containing H has a molar ratio of 2 to 30% H.
2. The magneto-optical recording medium according to claim 1, wherein the magneto-optical recording medium comprises: 3. The amorphous material containing H has a refractive index (n) of 1.75 to 3.
．． 3. The magneto-optical recording medium according to claim 1, wherein the magneto-optical recording medium has a diameter of 20. 4. The magneto-optical recording medium according to claim 1, 2 or 3, wherein the amorphous dielectric film material is formed by a sputtering method. 5. The magneto-optical recording medium according to claim 1, wherein the dielectric layer is made of an amorphous material consisting of amorphous Si:H. 6. The magneto-optical recording medium according to claim 1, wherein the dielectric layer is made of an amorphous material consisting of amorphous SiGe:H. 7. The magneto-optical recording medium according to claim 1, wherein the dielectric layer is made of an amorphous material consisting of amorphous SiN:H.