JPS6139955A - Optomagnetic recording medium - Google Patents

Abstract

PURPOSE:To prevents the oxidative corrosion of a magnetic film and to permit stable high-density recording and reproduction by consisting a protective film of the nitride of the group III-V elements of periodic table except silicon. CONSTITUTION:The protective film is constituted of the nitride of the group III, IVor V elements (except silicon) of the periodic table having an excellent effect of preventing oxidation deterioration. Various sputtering methods, CVD methods, ion plating methods, etc. are adopted as the methods for forming the protective film. The recording and reproduction are executed by irradiating modulated or deflected laser light from the substrate side or the opposite side.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magneto-optical recording medium capable of high-density recording and reproduction using laser light.

Prior Art Various types of magneto-optical recording media have been researched to perform magneto-optical recording and reproduction using laser light, but their basic structure consists of rare earth metals to non-transition metals on a transparent substrate such as a glass plate. Consists of crystalline alloys, polycrystalline alloys, etc. A magnetic film having an axis of easy magnetization perpendicular to the film surface is provided.

However, magnetic films made of the above materials, especially amorphous alloy magnetic films, are susceptible to oxidative corrosion due to oxygen and moisture in the air, and as a result, many pinholes occur during storage, and the magneto-optical properties deteriorate. (for example, coercive force) deteriorates and becomes unusable.

Therefore, in order to prevent such oxidative deterioration, a protective film such as STO, STO, etc. is usually provided on the magnetic film. However, the effect of preventing oxidative deterioration of conventional protective films is still insufficient.

Object The object of the present invention is to provide a magneto-optical recording medium in which oxidative corrosion of a magnetic film is prevented by using a material with a high oxidative deterioration prevention effect for the protective film.

Structure The magneto-optical recording medium of the present invention is a magneto-optical recording medium having a magnetic film having a busy axis of easy magnetization in a direction perpendicular to the film surface on a substrate, and a protective film on the magnetic film, wherein the protective film is a material of the periodic table except silicon. It is characterized by being made of a nitride of a Group III, IV or Group II element.

The basic configuration of the magneto-optical recording medium of the present invention is shown in FIG.
2 represents a substrate, 2 represents a magnetic film, and 3 represents a protective film. ) However, when a moisture permeable material such as acrylic resin is used as the substrate, in order to prevent moisture and oxygen from entering from the substrate side, the substrate and magnetic film should be connected as shown in Figure 2. A similar protective film 3' of elemental nitride can be provided between the two.

The magnetic film of the present invention is the same as the conventional one <<TbFeCo>.

Rare earth metals such as TbFe, GdTbFe, GdCo, transition metal amorphous alloys, Mnbi, MnCuB
1 grade polycrystalline alloys can be used. As a film forming method, an Rf sputtering method, a high temperature or low temperature magnetron sputtering method, a reactive snog sputtering method, a photo CVD method, a plasma CVD method, an ion blating method, etc. can be adopted. However, in any method, before actually forming a film, 1. In order to remove oxidizing components and dust that have adhered or adsorbed to the substrate surface, material (target material), etc.,
It is necessary to take an appropriate removal means such as a pre-sputtering process in the case of the sputtering method (a process in which the inside of the apparatus is maintained under film-forming conditions for a certain period of time while the shutter on the target material is closed). The thickness of the magnetic film is 100X~1
Approximately μm is appropriate.

The protective film of the present invention is composed of a nitride of a group III, IV, or V element (excluding silicon) of the periodic table, which has an excellent effect of preventing oxidative deterioration. Specific examples of nitrides of these elements include those of group Ⅰ: AIxN, , Ta! N, ,
BxNy, 5cxN, , Y, N, , Ra, N
, etc., but in group II, TizNy HZrxNy
l'rh3cN, etc., and in group II, vxN
Examples include a.

The above nitrides are known as ceramic materials.
It is also available as a commercial product. The protective film can be formed using various sputtering methods or C
A VD method, an ion silating method, or the like is employed.

Appropriate thickness is about 500X to 2 μm.

Substrate materials include glass such as slide glass, quartz glass, and glass; silicon with or without oxidation treatment; Al, O,, AI, O, .MgO, Mg
O.LiF,y,o,@1. iF', BeO,
Zr01@Y101°The, transparent ceramic material such as CaO; resin such as acrylic resin, polycarbonate, polyester, etc. is used.

Recording and reproduction using the magneto-optical recording medium of the present invention is carried out by irradiating modulated or deflected laser light from the substrate side or the opposite side, as in the conventional case.

Effects As described above, in the magneto-optical recording medium of the present invention, the protective film is made of a nitride of a group III, IV, or group III element that has excellent oxidative deterioration prevention properties, so oxidative corrosion of the magnetic film is prevented, and this Therefore, stable high-density recording and reproduction can be performed at all times.

Examples of the present invention are shown below.

Example 1 Two types of Tb on a 150111111φ iron plate
Chituzo (101111 x 10 parrots x 2 and 5 fights x 5-x
2) and two types of co chips (size Tb
The target material was made by regularly arranging the materials (same as Chituzo). Next, a slide glass plate - (size 761111 x 26 m++ Then, both shutters were opened and discharge was continued for 3 minutes under the same conditions to perform main sputtering.
A magnetic film made of Feco was provided.

Residual gas pressure: 7~8 x 10 Torr Ar gas pressure: 1.5 x 10 Torr discharge power: 400
W Next, replace the target material with AIxN A, perform press/J tattering by discharging for 60 minutes under the following conditions, then open the shutter and continue discharging for 40 minutes under the same conditions to perform main sputtering to form a 1500X thick A.
A magneto-optical recording medium A as shown in FIG. 1 was prepared by providing a protective film of lxNy.

Residual gas pressure: 7 to 8 X 10 Torr Ar gas pressure: 1.0 X 10 Torr discharge crab 200 W Example 2 Magneto-optical recording medium B was prepared in the same manner as in Example 1, except that Ti3IN was used as the target material for the protective film. Created.

Example 3 A magneto-optical recording medium C was produced in the same manner as in Example 1, except that Ta zNy was used as the target material for the protective film.

Comparative Example 1 A magneto-optical recording medium without a protective film was produced in the same manner as in Example 1 except that no protective film was provided.

Comparative Example 2 A magnetic recording medium E was produced in the same manner as in Example 1 except that Si20 was used as the target material for the protective film.

Next, the magneto-optical recording media A-E obtained as described above were stored in an atmosphere of 70°C and 904RH, and changes in coercive force (coercive force after storage Hc'/initial coercive force) were examined. 3～
The results shown in Figure 6 were obtained. As can be seen from these figures, the products A to C of the present invention using nitrides of Group I to V elements as the material for the protective film show almost no change after 850 hours;
A comparative product without a protective film and S10. as the material of the protective film.
Comparative product E using the magnetic film shows progressive deterioration of the magnetic film and a large decrease in coercive force.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of the magneto-optical recording medium of the present invention, and 3 and 3 are cross-sectional views of the magneto-optical recording medium of the present invention.
Figure 5 is a graph showing the change in coercive force due to storage of the magneto-optical recording media prepared in Examples 1 to 3, respectively, and Figure 6 is a graph showing the changes in coercive force due to storage of the magneto-optical recording media made in Examples 1 to 3, respectively, and Figure 6 is a graph showing the changes in coercive force due to storage of the magneto-optical recording media made in Examples 1 to 3.
2 is a graph showing the change in coercive force of the magneto-optical recording medium prepared in Example 2. 1...Substrate 2...Magnetic film 3.3'...
- Protective film A... Magneto-optical recording medium B produced in Example 1... Magneto-optical recording medium C produced in Example 2... Magneto-optical recording medium D produced in Example 3... Comparison Magneto-optical recording medium E produced in Example 1...Magneto-optical recording medium He produced in Comparative Example 2...Initial coercive force He'...Coercive force after storage Patent applicant Rico Co., Ltd. - Agent Patent attorney Tsukimura Shigegai (1 person)

Claims (1)

[Claims] 1. In a magneto-optical recording medium having a magnetic film having an axis of easy magnetization in a direction perpendicular to the film surface on a substrate and a protective film thereon, the protective film is made of a material belonging to Group III or IV of the periodic table excluding silicon.
A magneto-optical recording medium comprising a nitride of a group element or a group V element.