JP3022642B2 - Method for manufacturing magneto-optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magneto-optical recording medium, and more particularly to a method for manufacturing a rewritable magneto-optical disk, using a magneto-optical effect such as a magnetic card effect or a magnetic Faraday effect. The present invention relates to a readable magneto-optical recording medium.

[0002]

2. Description of the Related Art The following conditions are mainly required as materials for magneto-optical recording media. (A) A perpendicular magnetization film. (B) have a large coercive force; (C) The car rotation angle is large. It has been known that when heavy rare earths such as Tb and Gd are added to Fe and Co, the magnetic anisotropy increases and the film becomes a perpendicular magnetization film. Therefore, GdTbFe, DyFe, GdCo, TbCo, Tb
A heavy rare earth 3d transition metal amorphous alloy thin film such as DyFe or TbFeCo satisfies the above conditions and is suitable for mass production;
Promising because there is no readout noise. In particular, TbFeCo is promising and has become a practical material.
Disk substrates are roughly classified into two types: glass substrates and resin substrates. Among them, the glass substrate is easily damaged and is expensive, so that the resin substrate is mainly used. As the resin substrate, polycarbonate, polymethyl methacrylate, polyolefin, or the like is used in terms of mass productivity, price, and optical characteristics. On the other hand, it has been studied to use a short wavelength laser as a means for increasing the density of magneto-optical recording and to reduce the recording area. However, in the case of a heavy rare earth -3d transition metal amorphous alloy thin film, the car rotation angle becomes smaller as the wavelength becomes shorter. For this reason, a new short-wavelength magneto-optical recording material is required. The MnBi compound is
When a Mn-Bi laminated film in which Bi and Mn are sequentially formed on a substrate is heated and reacted, the C-axis orientation of Bi is preserved,
It becomes a C-axis oriented MnBi compound. The MnBi compound is
Since it has strong magnetic anisotropy in the C axis, it becomes a perpendicular magnetization film. In addition, the MnBi compound has a carrer even in a short wavelength region.
Because of its large rotation angle, it is promising as a short wavelength magneto-optical recording material. Mn-Bi in which Bi and Mn are sequentially formed on a substrate
In order to heat and react the laminated film, it is necessary to maintain the laminated film in an atmosphere at a temperature of 300 ° C. or higher, and the reaction is generally performed in a vacuum electric furnace to prevent oxidation.

[0003]

However, MnB
There are the following problems in using i as a magneto-optical recording material. That is, in order to heat and react to 300 ° C. or more in a vacuum electric furnace, it is necessary to use a substrate material that can withstand that temperature. Since the resin completely exceeds the softening point, only a glass substrate can be used. Glass substrates are expensive because they have poorer workability than resin substrates.
For this reason, a magneto-optical disk using MnBi as a recording material has a disadvantage that it is more expensive than a conventional magneto-optical disk. The present invention solves such a problem and provides MnB
It is an object of the present invention to provide a method for manufacturing a magneto-optical recording medium using an i-compound as a recording material using a resin substrate.

[0004]

According to the present invention, there is provided a method for manufacturing a magneto-optical recording medium using a MnBi compound as an information recording material, wherein Bi and Mn are sequentially formed on a polycarbonate substrate to form a Mn-Bi laminated film. A step of irradiating the Mn-Bi laminated film with a focused laser beam and locally heating the Mn-Bi layer without deforming the polycarbonate substrate.
A method of manufacturing a magneto-optical recording medium, comprising at least a step of forming a compound.

[0005]

The problem when the Mn-Bi laminated film is heated and reacted in an electric furnace is that not only the Mn-Bi laminated film requiring a high temperature but also the substrate is exposed to the high temperature. This problem cannot be avoided when the entire recording medium is heated by an electric furnace or the like. In the present invention, in order to avoid the above-mentioned temperature rise of the substrate, the Mn-Bi laminated film is irradiated with a focused laser beam and locally heated to form a MnBi compound without adversely affecting the substrate. . For this reason, MnBi
An inexpensive resin substrate can be used for a magneto-optical disk using a compound as a recording material.

[0006]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial sectional view of a magneto-optical recording medium before a heat treatment. In this magneto-optical recording medium, an intermediate layer (a silicon nitride film formed by sputtering) 2 is formed to a thickness of 95 nm and a Bi layer 3 is formed on a polycarbonate substrate 1 by vapor deposition.
The Mn layer 4 has a thickness of 12 nm by vapor deposition, the interference layer (silicon nitride film formed by sputtering) 5 has a thickness of 20 nm, and the reflection layer (Al film formed by sputtering) has a thickness of 30 nm. Form sequentially. In this magneto-optical recording medium, Mn
As a result, the MnBi compound could be formed without deforming the polycarbonate substrate 1 by locally irradiating the laser light focused on the -Bi laminated film. At this time, the car rotation angle was 2 degrees at a wavelength of 500 nm, and the square shape of the hysteresis loop was also good. On the other hand, when this medium was heated at 300 ° C. in a vacuum electric furnace, the polycarbonate substrate 1 was melted and deformed. Bi,
The Mn layer can be formed by a sputtering method, an ion plating method, an ion cluster beam method, or the like, in addition to a vapor deposition method.

[0007]

As described above, the method for manufacturing a magneto-optical recording medium according to the present invention can provide an inexpensive and high-performance magneto-optical recording medium in which a MnBi compound can be formed on a resin substrate. it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an example of a magneto-optical recording medium according to the present invention before heat treatment. DESCRIPTION OF SYMBOLS 1 Polycarbonate board 2 Intermediate layer 3 Bi layer 4 Mn layer 5 Interference layer 6 Reflection layer

Claims (1)

(57) [Claims] 1. A method for manufacturing a magneto-optical recording medium using an MnBi compound as an information recording material, comprising the steps of sequentially forming Bi and Mn on a polycarbonate substrate to form a Mn-Bi laminated film; The polycarbonate is irradiated with a laser beam focused on the film and locally heated.
Forming a Mn-Bi compound without deforming the substrate .