JPS61206946A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent the oxidation and corrosion of a thin magnetic film and to stabilize recording characteristics by forming a carbon film as a protective film on the thin magnetic film. CONSTITUTION:This photomagnetic recording medium is obtd. by providing the carbon film 3 as the protective film on the thin magnetic film 2 formed on a substrate 1. The formation of the carbon film 3 is possible by DC or high- frequency sputtering, ion beam sputtering, ion beam vapor deposition or plasma CVD, etc. and in either case, the formation under the conditions under which the dense structure is obtainable is preferable. The optimum thickness of such thin carbon film is in a 50-10,000Angstrom , more preferably 100-1,000Angstrom range.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magneto-optical recording medium in which a magnetic thin film for optical recording is formed on a substrate and information is recorded, reproduced, and erased using laser light. It is.

[Prior Art] Conventionally, a magneto-optical recording medium in which a magnetic thin film 2 for magneto-optical recording is provided on a glass or plastic substrate l as shown in FIG. -3
1703), while this 4 magneto-optical recording medium is
If they were in direct contact with the atmosphere, they would be oxidized or corroded by the oxygen and water in the atmosphere, changing the conditions for recording and reproducing information, making them unreliable. Therefore, a protective film 3 is generally provided on the magnetic thin film 2 as shown in FIG. Such a protective film 3' may be made of an oxide such as Sin, 5i02, or a nitride (such as AIM, 5i3Na, etc.).
JP 59-110052), Ag.

Metals such as AI and Cu that also serve as reflective films (Japanese Patent Application Laid-Open No. 58-80441, etc.), and resins to which pigments are added (Japanese Patent Application Laid-Open No. 1110443-1982) have been proposed. However, these materials are somewhat permeable and phenomena such as oxidation or corrosion are observed. For this reason, special care must be taken to preserve these magneto-optical recording materials, such as placing them in a desiccator.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a magneto-optical recording medium that is highly reliable and easy to handle. It's about doing.

[Means for Solving the Problems] The present invention solves the above-mentioned problems, and in a magneto-optical recording medium in which a magnetic thin film is formed on a substrate, a carbon film is provided as a protective film on the hills of the magnetic thin film. It has been established.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the basic configuration of the present invention. In the figure, 1 is a glass substrate made of soda lime, alkali-free glass, borosilicate glass, quartz glass, or the like. Reference numeral 2 denotes a magnetic thin film such as TbFe, which is made of an alloy of rare earth and transition metal and has magnetic anisotropy in a direction perpendicular to the film surface. 3 is a carbon protective film. Plastics such as PMMA (polymethyl methacrylate) and PC (polycarbonate) can be used as the first material, but due to the moisture permeability, hygroscopicity, or oxygen permeability of the resin material, the magnetic thin film that is the recording medium may be oxidized and its characteristics may deteriorate. Because of the phenomenon of deterioration, it is preferable to use the above-mentioned glass. Magnetic thin B'J
2: G+1pie, GdTbFe, CdC
o.

It is also possible to use alloys of other rare earths and transition metals such as TbFeGo, or these rare earths and transition metals with impurity elements added.

Next, a method of manufacturing one embodiment of the above-mentioned magneto-optical recording medium will be explained. A TbFe film 2 is formed as a magnetic thin film on a soda lime glass substrate 1 with a thickness of 1 to 2 cm, and a carbon thin W film is formed as a thin insulation film! A3 and A3 were formed in this order. The TbFe thin film can be formed by vacuum evaporation, sputtering, ion blating, etc., but the TbFe film 2 must have magnetic anisotropy in the direction perpendicular to the film surface. High-frequency sputtering was used because it was easy to obtain , and it was easy to obtain reproducibility and uniformity of film formation. The carbon film 3 can be formed by direct current or high frequency sputtering, ion beam sputtering, ion beam evaporation, plasma CVD, etc.
In either case, it is best to form the carbon thin film under conditions that allow a dense structure to be obtained.
Range of 10,000 people, preferred heathers are 100 to 100 people
0 people is optimal.

If the thickness of the carbon thin film is less than 100A, it becomes a discontinuous film and does not play its role as a protective film, which is undesirable.If it is thicker than 1G000, internal stress becomes large and it tends to peel off, resulting in poor durability. This is not preferable because it takes a long time to form a film.

A corrosion resistance test was conducted on the magneto-optical recording medium formed in the above practical example. The corrosion test was conducted by leaving the sample in an environment with a temperature of 60° C. and a humidity of 95%.

The presence or absence of corrosion was determined by observing the surface of the magneto-optical recording medium using an optical microscope. In addition, as comparative samples, one with the structure shown in FIG. 2 without any protective film (Comparative Example 1), and one with the structure shown in FIG. 3 using Si02 as a protective film (Comparative Example 2) were used. The results of the corrosion test are shown in Table 1.

Table 1 The gist of the present invention is a magneto-optical recording medium 1 consisting of a magnetic thin film that exerts a magnetic anisotropic force in the direction perpendicular to the substrate and the film surface, and a carbon protective film having a dense structure. It also makes it possible to prevent the permeation of moisture. Therefore, it is possible to adopt various configurations without departing from this spirit. For example, in order to emphasize the Kerr effect, a dielectric film is sandwiched between the substrate 1 and the magnetic thin film 2 shown in FIG.
It is also possible to have a configuration in which a reflective film or a dielectric film and a reflective film are sandwiched between .

[Effects of the Invention] According to the present invention, since the carbon protective film has a dense structure, it prevents oxidation and corrosion of a magnetic thin film having magnetic anisotropy perpendicular to the film surface, and stabilizes recording characteristics. The advantage is that the carbon film can easily increase the temperature of the magnetic thin film because it is a material with high light absorption, and that thermal energy can be used efficiently.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention. Figure 2,
Fig. 3 is a cross-sectional view showing a conventional example, in which 1: substrate, 2: magnetic thin film, 3: carbon protective film, 3''
: Indicates a protective film. Figure 1 Rate 2 Figure Star 3 Figure

Claims (1)

[Claims] (1) A magneto-optical recording medium comprising a magnetic thin film formed on a substrate, characterized in that a carbon film is formed as a protective film on the magnetic thin film.