JPH01196754A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To improve recording sensitivity and heat resistance by providing a thin film consisting of a specific mixture adjacently to a magneto-optical recording film. CONSTITUTION:A thin film 4 consisting of an org. matter-nitrided metal mixture formed by incorporating about 50vol.% Si3N4 into a thin film of polytetrafluoroethylene is provided on the non-light irradiation surface of the magneto-optical recording film 3. The film 3 is the thin film of the amorphous rare earth-transition metal. A thin film 2 of the transparent dielectric material has a Kerr enhancement function and a protective film 5 of a dielectric material has a protective function, respectively. The org. matter of the film 4 may be polyimide and the nitride metal may be any of AlN, TiN, NfN, TaN, BN, ZrN, UN, ThN, BeN, NbN or VN. The recording density is then improved and the heat resistance as against overpower at the time of recording and erasing is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magneto-optical recording medium used in a photothermal magnetic recording/reproducing device.

Conventional technology In recent years, optical disks have been developed as a type of large-capacity memory.
Commercialization is active. Among these, efforts are being made to develop rewritable magneto-optical disks.

A conventional magneto-optical recording medium will be described below with reference to all the drawings.

Examples of recent magneto-optical disks are shown in Figure 4 (for example, Figure 8).
Japanese Society of Applied Magnetics Academic Lecture Abstracts November 1984 P
224).

In FIG. 4, 1 is a resin or glass annular substrate in which grooves or pits are formed in a circular or spiral shape; 2;
3 is a transparent dielectric thin film such as ZnS, SiO2+ A/N, 5i3u4, etc., and 3 is TbFeCo with perpendicular easy axis of magnetization.
, TbFe, TbCo, DyFe, DyFeC
o magneto-optical recording film, 5 is A/N Ya 5i02. Si
This is a W dielectric protective film such as 3N4.

The functions of the conventional magneto-optical recording medium configured as described above will be explained below.

The material for the substrate 1 of the magneto-optical recording medium is (1) - Since the laser beam for recording and reproducing inside the shell is irradiated onto the magneto-optical recording medium from the substrate 1 side, it must be transparent and have little birefringence; (2) High speed; In order to provide the grooves and bits necessary for random access, it has excellent workability and moldability, and for this reason, we use glass 2P substrates, PMM, PC, epoxy, etc., which are coated with ultraviolet curable resin on a glass plate. Use transparent resin material.

The magneto-optical recording film 3 is a perpendicular magnetization film, and the focus of research and development is on amorphous rare earth transition metal thin films.

In the magneto-optical recording medium, a transparent dielectric thin film 2 with a high refractive index is placed adjacent to the magneto-optical recording film 3 for reasons such as improving characteristic deterioration due to oxidation of the magneto-optical recording film 3 and increasing Kerr rotation angle or Faraday rotation angle. However, the apparent structure is a car acceleration structure that increases the Kerr rotation angle, and a sandwich structure that prevents oxidative deterioration of the magneto-optical recording film 3 by adjoining the dielectric protective film 6.

Incidentally, the performance of an information storage device is determined by characteristics such as storage capacity, access speed, and data transfer speed. When a magneto-optical recording medium is used as a recording medium for an information storage device, sufficient characteristics are obtained in terms of storage capacity.

Problems to be Solved by the Invention However, since magneto-optical disks use heat mode recording, their sensitivity is lower than that of magnetic disks, and even when a commercially available high-power semiconductor laser (4 ohmw) is used, the data transfer rate is only 1M at most. It had the problem of being slow at bytes/second.

In view of the above-mentioned problems, the present invention provides a magneto-optical recording medium that has high recording sensitivity and can improve data transfer speed.

Means for Solving the Problems In order to achieve this object, the magneto-optical recording medium of the present invention has an organic material such as polytetrafluoroethylene, polyimide, etc. adjacent to the magneto-optical recording film.
ie, HfN, TaN, BN, ZrN, TiN, UN.

The structure includes an organic material-metal nitride mixed thin film formed by mixing one or more of metal nitrides such as ThN, BeN, NbN, and VN.

Effect With this configuration, since the thermal conductivity of the organic thin film is less than one-tenth that of the dielectric thin film, heat diffusion from the magneto-optical recording film to the organic material-metal nitride mixed thin film can be prevented, and the heat of the magneto-optical recording film can be prevented. Preservability is improved.

Furthermore, by mixing metal nitride with the organic substance, the magneto-optical recording film has heat resistance during recording and erasing, thereby preventing deterioration of the organic substance-metal nitride mixed thin film during repeated recording and erasing.

These increase the temperature rise of the magneto-optical recording film during laser beam irradiation, thereby increasing the thermal sensitivity of the magneto-optical recording medium and increasing the data transfer rate.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of a magneto-optical recording medium in an embodiment of the present invention. In FIG. 1, reference numeral 4 denotes an organic substance-metal nitride mixed thin film, which is a polytetrafluoroethylene thin film mixed with Si3N4 at about 60% (by volume), and is provided on the non-light irradiated side of the magneto-optical recording film. Note that 1 is a substrate, 2 is a transparent dielectric thin film, 3 is a magneto-optical recording film, and 5 is a dielectric protective film, which are the same as those in the conventional example.

The functions of the magneto-optical recording medium configured as described above will be explained below.

Transparent dielectric thin film 2, magneto-optical recording film 3, and dielectric protective film 5
has the same function as the conventional configuration. That is, the magneto-optical recording film 3 is an amorphous rare earth-transition metal thin film, the transparent dielectric thin film 2 has a car enhancement function, and the dielectric protective film 6 has a protection function.

In this example, TbFeCo was used as the magneto-optical recording film 3, ZnS was used as the transparent dielectric thin film 2, and 5i5N4 was used as the dielectric protective film 5. The film thickness is 880 people each.

1000A, 1000A.

Polytetrafluoroethylene has a heat insulating function. The thermal conductivity of polytetrafluoroethylene is 0-25 (J
/m-5-k), which is about 1/100 of that of 5i3N4(7) 20-60 (J/m-5-k), which is the constituent material of the dielectric protection 5. This shows that polytetrafluoroethylene provides a sufficient heat insulating effect compared to 515H4.

The heat insulating function of the organic material-metal nitride mixed thin film 4 that uses polytetrafluoroethylene as the organic material and 5i5N4 as the nitride metal is almost the same as that of polytetrafluoroethylene, and the thickness of the organic material-metal nitride mixed thin film 4 is 600X.
It has been experimentally confirmed that the above configuration has a sufficient heat insulation effect.

FIG. 2 shows the dependence of the recording sensitivity and S/N of the magneto-optical recording medium on the thickness of the organic substance-metal nitride mixed thin film 4. When the thickness of the organic substance-metal nitride mixed thin film 4 is 600A or more, the recording sensitivity is 4.
．． omw (linear velocity em/s),
e, o m w when the film thickness of the organic substance-metal nitride mixed thin film 4 is 0 (in the case of a magneto-optical recording medium with a conventional configuration)
(linear velocity am/s), the recording window degree is improved by about 30%. Further, the S/N has no dependence on the thickness of the organic substance-metal nitride mixed thin film 4, and characteristics similar to those of a magneto-optical recording medium having a conventional structure can be obtained.

By the way, magneto-optical recording media are generally used as disks, but when recording at a constant angular velocity, if the same intensity of laser output is used at the inner and outer peripheries of the recording area, the input power density on the disk will vary. differs by 1.5 to 2 times. Therefore, it is necessary to prevent deterioration due to temperature rise when writing with excessive power.

The organic material-metal nitride mixed thin film 4 of this example has improved thermal stability when heated with excessive power than that of the original organic material due to the mixture of metal nitride, and has stable heat insulating properties even when recorded with excessive power. Indicated.

FIG. 3 shows the change in recording sensitivity when excessive power recording is repeated. FIG. 3 shows the change in recording power when excessive power recording, erasing, and normal power recording are repeated. Excess power is approximately twice the normal power. When excessive power was repeatedly applied, there was almost no change in recording sensitivity.

As described above, according to this embodiment, by arranging the organic substance-metal nitride mixed thin film 4 adjacent to the magneto-optical recording film 3, the recording sensitivity can be improved by 30% or more. Furthermore, 5i5N4 is used as the metal nitride of the organic substance-metal nitride mixed film 4.
By adopting this, stable insulation properties were demonstrated even during overpower recording.

In this embodiment, polytetrafluoroethylene was used as the organic substance for the organic substance-metal nitride mixed thin film 4. However, polyimide may be used instead, and in this case, the effect of further improving the durability against overpower can be obtained.

Further, in this example, 5i5N4 was used as the metal nitride of the organic substance-metal nitride mixed thin film 4, but the metal nitride of the organic substance-metal nitride mixed thin film 4 was M/N, Tie, HfN.

TaN, BN, ZrN, UN, ThN, Be
Similar effects can be obtained with N, NbN, or VN.

Effects of the Invention The present invention improves recording sensitivity by providing an organic substance-metal nitride mixed thin film adjacent to a magneto-optical recording film and using polytetrafluoroethylene or hapolyimide as the organic substance of the organic substance-metal nitride mixed thin film. By mixing a metal nitride with an organic material to form an organic material-metal nitride mixture, an excellent magneto-optical recording medium can be created that improves heat resistance against overpower during recording and erasing. It is possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a magneto-optical recording medium in an embodiment of the present invention, and FIG. 2 is an organic substance-metal nitride mixed thin film with recording sensitivity and S/H of a magneto-optical recording medium in an embodiment of the present invention. A characteristic diagram showing the thickness dependence, FIG. 3 is a characteristic diagram showing the change in recording sensitivity when excessive power recording is repeated on a magneto-optical recording medium in an embodiment of the present invention, and FIG. 4 is a characteristic diagram showing a conventional magneto-optical recording medium. FIG. 1...Substrate, 2...Transparent dielectric thin film,
3...Magneto-optical recording film, 4...Organic substance-
Metal nitride mixed thin film, 5...Dielectric protective film. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
-Act 2-Kimei dielectric material 3-Light sharpening film 2nd figure A-Naka-Metal nitride mixed thin WL tumor 1 (Z → 3rd figure OTOO200,?00 Haruka?j Power input hole - Figure 4

Claims (2)

[Claims] (1) A magneto-optical recording medium comprising a magneto-optical recording film and an organic material-metal nitride mixed thin film which is in contact with the magneto-optical recording film and is formed by mixing an organic material and a metal nitride. (2) The organic substance is polytetrafluoroethylene or polyimide, and the metal nitride is SiN, AlN, Ti.
N, HfN, TaN, BN, ZrN, UN, ThN, B
The magneto-optical recording medium according to claim 1, characterized in that it contains one or more of eN, NbN, and VN.