JPS60143460A - Optothermomagnetic recording medium and its production - Google Patents

Abstract

PURPOSE:To improve the adhesion to a recording layer and to improve the compactness and oxidation resistance of a protective layer itself by incorporating rare earth elements and transition metals as an element for constituting a base body and carbon or nitrogen as a stabilizing element into the protective layer. CONSTITUTION:The inside of a vessel 1 is evacuated to a vacuum and thereafter a specified flow rate of gaseous Ar is introduced via 5 into the vessel 1 to maintain the gaseous pressure therein under a prescribed pressure. An electric power source 4 is then thrown to form a recording film consisting of a Tb-Fe alloy having a prescribed thickness on a substrate 3 by RF electric power. The power source 4 is once turned off and a specified flow rate of gaseous CH4 is introduced into the vessel 1. The mixing ratio of the gaseous CH4 with the gaseous Ar is made 20% in this stage and the pressure of the gaseous mixture is maintained under the prescribed pressure by adjusting the evacuating system. The RF power is again thrown to form a protective layer consisting of Tb, Fe and C having a prescribed thickness on the above-described recording film. In the constitution figure of the optothermomagnetic recording medium manufacture by the above-mentioned method, 8 is the glass substrate, 9 is the recording film consisting of the Tb-Fe alloy and 10 is the protective film consisting of Tb, Fe and C.

Description

Detailed Description of the Invention [Technical field to which the invention pertains] The present invention relates to a photothermal magnetic recording medium in which information is recorded and read out via a light beam, and a method for manufacturing the same, and particularly relates to a photothermal magnetic recording medium and a method for manufacturing the same, which have an improved lifespan. It relates to its manufacturing method.

[Prior art and its problems]

Amorphous alloy thin films made of rare earths and transition metals can be used as photothermal magnetic recording media because they are +11 amorphous and therefore have no grain boundary noise.
(lit) has perpendicular magnetic anisotropy over a wide composition range, (t
The material of the substrate is not particularly limited, and inexpensive substrates such as glass, silicon wafer, or organic materials such as acrylic can be used. (It has the advantage of being able to be easily mass-produced by applying simple film-forming techniques such as IVI evaporation and sputtering. However, it has the disadvantage of being easily oxidized in the atmosphere and lacking in reliability in terms of longevity. It is known that it is effective to cover the rare earth transition metal alloy layer with a protective layer for the purpose of preventing oxidation, without impairing the recording characteristics of the medium. In the prior art, as such a protective layer, a silicon first oxide or a silicon second oxide formed by a vapor deposition method or a sputtering method, or an organic resin material formed by a spinner coating method is used. In the conventional technology, the physical properties of the material of the protective film are significantly different from those of the recording film, so (1)
Make the protective film thicker than 1 μm (this makes it easy to peel off, +17
The protection film lacks density, and oxidation of the recording layer cannot be avoided with a protection film thickness of about 1 μm. (Lit) Because the sources (sputter target, evaporation source) for forming the recording film and the protection film are different, There were drawbacks such as difficulty in forming a film.

[Purpose of the invention]

The present invention has been made in order to solve the problems of the prior art described above, and provides a photothermal magnetic recording medium having a recording layer and a protective layer, which has good adhesion with the recording layer and has sufficient density. The object of the present invention is to provide a photothermal magnetic recording medium that has a protective layer that has a protective layer that itself has excellent oxidation resistance, and a method for easily manufacturing the medium.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention includes a photothermal magnetic recording layer made of a rare earth element and a transition metal, and a protective layer thereof.
The present invention relates to an opto-thermomagnetic recording medium having a thin film layer containing rare earths and transition metals and a small amount of carbon or nitrogen, and a method for producing the same.The protective layer contains rare earths and transition metals as basic constituent elements. It contains carbon or nitrogen as a chemical element, and (1) has excellent adhesion with the recording layer because its physical properties such as thermal expansion coefficient are close to those of the recording layer. (11) What are the rules for the recording layer? It is even more dense and almost impervious to gas, and forms a mixture of Ti+L+ itself with stable carbide or nitride or carbon or nitrogen, and has excellent properties such as oxidation resistance, weather resistance, and moisture resistance. It is extremely easy to form this protective layer before and after forming the recording layer.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of a manufacturing apparatus for a photothermal magnetic recording medium according to the present invention. In Figure 1, 1 is an airtight container;
2 is a composite target made of Tb and Fe (Tb area ratio = 40%), 3 is a glass substrate, 4 is an RF power source, 5 is Ar
A gas introduction system, 6 is a CH gas introduction system, and 7 is an exhaust system. With the above configuration, after the inside of the container 1 was evacuated to 2X10"torr, a constant flow rate of Ar gas was introduced through 5 to maintain the gas pressure inside the container 1 at 2Qmtorr. Next, the power supply 4 was turned on and the RF A recording film of 100 OA made of 'rb-Fe alloy was formed on the substrate 3 with a Kamikata force of 200 W. Next, the power supply 4 was turned off once, and a constant flow rate of CH and gas was introduced into the container 1. At this time. The mixing ratio of CH4 gas to Ar gas was 20%, and the exhaust system was adjusted so that the mixed gas pressure was 2Q mtorr.

Next, RF and power of 200 W were applied again to form a protective layer of 50 OA of Tb, Fe, and C on the recording film. FIG. 2 is a diagram showing the configuration of a photothermal magnetic recording medium manufactured by the method described above. 8 is a glass substrate, 9 is a film thickness of 100
Recording film made of 0A 'rb-Pe alloy, 10 has a film thickness of 5
In a recording medium having a protective film made of 00A Tb, Fe, and C, the original beam for recording and reading information is irradiated through the substrate.

The hysteresis loop of the photothermal magnetic recording medium shown in FIG. 2 was measured using a vibrating sample magnetometer.

Measurements were carried out (immediately after the medium was created, temperature: 40°C, humidity: 98°C).
% after being left in a constant temperature and humidity chamber for 10 hours, no significant difference was found between the two. For comparison, a single-layer recording medium (referred to as sample A-1) and sample A-1 were prepared using the same apparatus as described above and with 1000 people under the same conditions for forming a Tb-Fe recording film as in the above example. Tb same as
-A two-layer recording medium (sample A-
2) was manufactured and the same measurements as in the above example were performed. As a result, sample A-1 was measured immediately after the medium was created. A
-'' Both showed the same hysteresis loop as in the previous example, but in a constant temperature and humidity chamber (40°C).

Sample A-
In the case of sample A-1, both the saturation magnetization and coercive force almost disappear, and in the case of sample A-2, the saturation magnetization is about 2
/3, and the coercive force decreased to about 1/2 in the same comparison. As is clear from this comparative example, the lifetime of the photothermal magnetic recording medium using the protective layer of the present invention is significantly improved in corrosion resistance compared to the conventional one.

FIG. 3 is a block diagram of another embodiment of the photothermal magnetic recording medium. 11 is an acrylic substrate, 12 is a T with a film thickness of 100 Å or less
b, a first protective film consisting of Fe, and C; 13 is 'rb-r;
A recording film made of e alloy, 14 is Tb with a film thickness of 500A,
This is a second protective film made of Fe and C. In this configuration, as in the configuration shown in FIG. 2, the original beam for reading the recording 9 is irradiated through the substrate side. In this case, by setting the thickness of the first protective film layer to 100 A or less, most of the incident light beam can be transmitted through the first protective layer and reach the recording film. However, the protective layer in the present invention is also effective when using a substrate made of an organic resin material such as acrylic that has gas permeability, and can also be used as a film that prevents oxidation due to oxygen molecules in the atmosphere that pass through the substrate. Can be used.

Further, in the above example, Tb was used as the rare earth in the recording layer and the protective layer, Fe was used as the transition metal, and T was used as the rare earth in the protective layer.
b. Only examples using Fe as the transition metal have been described;
It is clear that the present invention is also effective when using recording films made of combinations of transition metals other than Fe (e.g., Co, Ni, etc.). Also, when nitrogen was used instead of carbon as a stabilizing element in the protective layer, the corrosion resistance was improved as in the above example.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the method for manufacturing a photothermal magnetic recording medium of the present invention, FIG. 2 is a block diagram of an embodiment of the photothermal magnetic recording medium of the present invention, and FIG. 3 is a block diagram of an embodiment of the method for manufacturing a photothermal magnetic recording medium of the present invention. FIG. 3 is a configuration diagram of another embodiment of a recording medium. DESCRIPTION OF SYMBOLS 1... Airtight container, 2... Target, 3... Substrate, 4... Power supply, 5.6... Gas introduction system, 7... Exhaust system, 8゜11... Substrate, 9.13...Recording film, 1
0,12.14...Protective film. Representative Patent Attorney Kensuke Chika (and 1 other person) Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] (1) A first thin film layer that becomes a recording layer made of an amorphous alloy containing rare earths and transition metals and having an axis of easy magnetization perpendicular to the substrate surface; and a second thin film serving as a protective layer.
(2) A first thin film layer that serves as a recording layer, the thin film layer of which is made of a non-alloy containing rare earth and transition metals and has an axis of easy magnetization perpendicular to the substrate surface; A method for manufacturing a photothermal magnetic recording medium by a sputtering method, which comprises a second thin film layer serving as an abrasion layer, wherein the first
．． The same target is used throughout the formation of the second thin film layer, and the target is sputtered with pure argon gas plasma during the formation of the first thin film layer. A method for producing a photothermal magnetic recording medium, characterized in that when forming the second thin film layer, the target is sputtered with a mixed gas plasma of argon and methane or nitrogen. (3) Consisting of a non-alloy containing rare earths and transition metals,
A photothermal magnetic recording medium comprising a first thin film layer serving as a recording layer and having an axis of easy magnetization perpendicular to the substrate surface, and a second thin film layer serving as a storage layer in addition to the thin film is manufactured by a vapor deposition method. In this method, the same evaporation source is used throughout the formation of the first and second thin film layers, and the particles evaporated from the evaporation source are passed through a vacuum or pure argon gas plasma when forming the first thin film layer. A method for producing a photothermal magnetic recording medium, characterized in that the evaporated particles are deposited on a substrate, and when forming the second thin film layer, the evaporated particles are passed through a mixed gas of argon and methane or nitrogen or through a plasma of the mixed gas to be deposited on the substrate. .