JPS62275339A - Production of magneto-optical disk - Google Patents

Abstract

PURPOSE:To eliminate the sticking of an excessive film to the rear surface of a transparent disk substrate and to obtain a disk having the uniform compsn. of the material consisting the magnetic material of a recording layer by providing a disk for preventing spreading of the film forming material to the rear surface of the surface to be formed with the film of said substrate so that the spreading of the film forming material to the rear surface of the substrate is prevented. CONSTITUTION:The transparent circular substrate 1 is coupled via a spacer 3 to the disk 2 for preventing the spreading of the material to the rear side thereof and is held and rotated by a revolving shaft 6. An underlying protective film is first formed of Al2O3, AlN, etc. thereon and the magnetic layer is formed thereon by using TbFe, TbFeCo, etc.; further, a surface protective layer consisting of Al2O3, AlN, etc., is formed thereon. Since the disk 2 exists during sputtering, the film does not stick to the rear surface of the substrate 1. A space is formed at 0.1 - several millimeters between the two disks by the spacer 3 and therefore, the generation of the uneven compsn. of the material consisting the magnetic material of the recording layer formed on the surface of the transparent disk substrate is obviated.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to a method of manufacturing a magneto-optical disk.

[Conventional technology]

Magneto-optical disks are attracting attention as a high-density, large-capacity memory recording medium that can be erased and rewritten, and research on them,
Development is underway.

Information is recorded on this optical disk by applying a magnetic field to the disk, irradiating it with a laser, raising the temperature above the Curie point, and reversing the direction of magnetization. Information is reproduced using the magneto-optic effect, in which the reflected light of the laser light irradiated onto the disk is rotated in directions with different polarization angles.

As described above, magneto-optical disks on which information is recorded and reproduced have T, F, , Tt, which have perpendicular magnetic anisotropy on the transparent substrate surface that transmits and reflects laser light.

A magnetic thin film recording layer made of a material such as F or C is provided by a method such as sputtering, vapor deposition, or ion plating.

For example, in the sputtering method, while rotating the transparent substrate, a substance released from a target is deposited on the surface of the transparent substrate to form a base protective layer, a recording layer, and a protective layer in this order. In this case, the film material also adheres to the back surface of the transparent substrate due to wraparound.

This adhered film becomes a hindrance when performing recording and configuration when a laser beam is incident from the substrate side, and has a particularly bad effect on reproduced signals at the outer periphery.

In order to prevent the film from adhering to the back surface of the transparent substrate, a method has been devised and implemented in which a wrap-around prevention disc separate from the transparent substrate is provided in close contact with the back surface of the transparent substrate.

[Problem to be solved]

In the case of the above-mentioned method, although adhesion of the film due to wrapping was prevented, a phenomenon occurred in which the composition of the constituent substances of the magnetic material changed in the circumferential direction of the transparent circular substrate.

The results of analyzing the amount of elements using EPMA at three arbitrarily selected locations on the same track (circumference) are shown in Figure 4, where the composition amounts of C0% Fe and Tb vary, and the difference is 2.
It can even reach %. As a result, the amplitude of the reproduced signal changes, which may even lead to data loss.

A possible cause of the above phenomenon is that the temperature of the transparent circular substrate is not constant because the transparent circular substrate on which the film is to be formed and the wraparound prevention substrate do not come into complete contact with each other.

Therefore, this invention maintains a constant temperature distribution of the substrate on which the film is formed by creating a gap of 0.1 to several millimeters between the two substrates, thereby keeping the proportion of the material constituting the recording layer constant. An object of the present invention is to provide a method for manufacturing a magneto-optical disk having sufficient recording and reproducing characteristics when a laser beam is incident from the substrate side.

[Means for solving problems]

In order to achieve the above object, the present invention provides magneto-optical recording that performs recording and reproduction using magneto-optic effects on a rotating transparent circular substrate in a vacuum apparatus using a vapor deposition method, a sputtering method, an ion plating method, etc. In the process of manufacturing a magneto-optical disk in which a medium is provided, a layer of 0.0 mm is applied to the back surface of the surface of the transparent circular substrate on which a film is to be formed from the back surface of the transparent circular substrate.
A wrapping prevention disk having a gap of 1 to several millimeters and having the same size as the transparent circular substrate is provided, and a vacuum device is used to prevent the coating material from wrapping around the back surface of the transparent substrate during film formation. We have developed a method for manufacturing a magneto-optical disk in which the ratio of constituent materials at each point on the same circumference of the transparent circular substrate is constant.

[Effect]

PMMA, PC to form a magneto-optical disk.

A wraparound prevention disk is attached to the center of the back side of the film-forming surface of a transparent circular substrate made of glass, epoxy, etc., with a spacer having a thickness of 0.1 to several millimeters interposed therebetween.

While rotating this transparent circular substrate in an Ar gas atmosphere, a base protective layer such as Al z03, Al SiO□
Provide a protective layer such as

When using the sputtering method, if there is a gap of 0.1 to several millimeters between the transparent circular substrate and the wraparound prevention disk, the sputtered material can be prevented from going around. In addition, because there is a gap between the sputtering disk and the wraparound prevention disk, the temperature of the transparent circular substrate remains uniform.
The composition of the constituent materials of the magnetic material of the recording layer becomes uniform.

〔Example〕

An embodiment of the invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram illustrating the implementation state of this invention, and FIG.
The figure is a perspective view showing a state in which the transparent circular base body and the wraparound prevention disk are coupled.

A transparent circular base 1 is connected to a rotation prevention disc 2 via a spacer 3, and is held and rotated by a rotating shaft 6.

A target 5 on which a material to be sputtered is applied on-chip is placed on the surface of the transparent circular substrate 1 to be sputtered, and the entire target 5 is placed in an Ar gas atmosphere in a vacuum chamber 4 to allow Ar gas to flow therethrough.

When a voltage is applied to the target 5, a discharge phenomenon occurs in the vacuum chamber 4, and the Ar positive bioions in the plasma are accelerated and collide with the target 5. The material on the target is ejected by the impact and is deposited on the surface of the transparent circular substrate.

First, a base protective layer is formed using ANzO:+, Alx, etc., a magnetic layer is formed using 'l''bl''e, TbFeCo, etc., and a surface protective layer is formed thereon using /1203, AZN, etc. Since there is a wraparound prevention disk 2 in the sputtering process, no film is deposited on the back surface of the transparent circular substrate 1.

Further, since there is a distance of O01 to several millimeters between the two disks due to the spacer 3, no unevenness occurs in the composition of the constituent material of the magnetic material of the recording layer formed on the surface of the transparent circular substrate.

〔effect〕

As explained above, according to the manufacturing method of the present invention, it is possible to manufacture a disk in which no excess film is deposited on the back surface of the disk substrate and the composition of the magnetic material in the recording layer is uniform. There is no interference with recording and reproduction when the substrate is incident on the substrate due to adhesion of substances that have gone around to the back surface, and there is no local compositional deviation of the magnetic material in the recording layer, and the reproduction amplitude is stable.
A magneto-optical disk having good C/N and reproduction amplitude over the entire disk can be provided.

FIG. 3 shows the C/N when the recording trunk diameter at the time of incidence on the substrate is changed for the case of only the disk substrate and the case of the present invention. If the film is formed only on the disk substrate, the C/
N, both recording and playback are low, especially when recording and playing around the outer periphery.
Although a decrease of about 6 dB was observed, in this case, good C/N and reproduction amplitude can be obtained over the entire circumference regardless of the inner or outer circumference of the disk.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram illustrating the implementation state of the present invention, Fig. 2 is a perspective view showing the state of the transparent circular substrate and the disc for preventing rotation, and Fig. 3 is the case of only the disc substrate and the case of the present invention. C/ when the recording track diameter at the time of substrate incidence is changed for
FIG. 4, which is a diagram showing N, shows EPMA analysis data at arbitrary three points on the same track near the outer periphery when the wrap-around prevention disk is assembled with a transparent circular base. 1...Transparent circular substrate, 2...Disc for preventing rotation, 3...Spacer, 4...Vacuum chamber, 5... ·target. Applicant NEC Home Electronics Co., Ltd. Agent Patent Attorney Masu 1) Takeo No. 1 Figure 20

Claims (1)

[Claims] 1. Magneto-optical recording medium that performs recording and reproduction using the magneto-optic effect on a rotating transparent circular substrate in a vacuum apparatus using a vapor deposition method, sputtering method, ion plating method, etc. In the manufacturing process of the disk, on the back side of the surface on which the film is formed of the transparent circular substrate, there is a gap of 0.1 to several millimeters from the back surface of the transparent circular substrate, and the gap has the same size as the transparent circular substrate. A method for producing a magneto-optical disk, comprising: providing a wrap-around prevention disc to prevent a film-forming substance from wrapping around to the back surface of the transparent circular substrate during film formation using a vacuum device.