JPH0442451A - Magneto-optical disk and production of magneto-optical recording medium used for this magneto-optical recording disk - Google Patents

Abstract

PURPOSE:To obviate the deterioration of recording films by oxidation even if the recording films are made into a non-columnar structure by providing a protective film on a substrate, successively laminating and providing a non-columnar structure recording film, a columnar structure recording film, and a non-columnar structure recording film on the protective film and further providing the protective film on the uppermost layer. CONSTITUTION:The protective film 22-1 for protecting the recording films 23-1, 23-2, 24 against oxidation is provided on the substrate 21 consisting of glass, etc., having guide grooves for a laser beam and the non-columnar structure recording film 23-1, the columnar structure recording film 24 and the non-columnar structure recording film 23-2 are successively laminated and provided on the protective film 22-1; further, the protective film 22-2 is provided on the uppermost layer. Namely, the columnar structure recording film 24 which is liable to oxidize is protected by pinching this film with the non-columnar structure recording films 23-1, 23-2 strong to the oxidation to prevent the infiltration of the oxygen from the protective film 22-1, 22-2 side to the recording film 23-1, 23-2 side and the sticking of the oxygen at the boundaries are prevented. The easy oxidation of the recording film 24 is prevented in this way even if this film is made into a columnar structure.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a magneto-optical disk and a magneto-optical recording medium used in the magneto-optical disk, even when a recording film has a columnar structure in order to improve recording sensitivity, Aiming at a magneto-optical disk in which the recording film does not deteriorate due to oxidation, a protective film is provided on the substrate, and a non-columnar structure recording film, a columnar structure recording film, and a non-columnar structure recording film are sequentially laminated on the protective film. A protective film is further provided on the top layer.

[Industrial application field]

The present invention relates to a magneto-optical disk that performs recording and reproduction using laser light, and a method of manufacturing a magneto-optical recording medium used in the magneto-optical disk.

In recent years, systems using electronic computers are required to be larger, faster, and more dense.

Among these, magneto-optical disks, which are rewritable high-density recording media, are attracting attention. Although magneto-optical disks are high-density recording media, they have a problem in that their transfer speed is slower than that of magnetic disks. In order to solve this problem, it would be good to increase the rotational speed of the magneto-optical disk, but increasing this rotational speed also improves the recording sensitivity of the recording medium so that information can be written with a small laser power. There is a need.

FIG. 6 schematically shows the structure of a columnar recording film as a magneto-optical recording medium with improved recording sensitivity as described above. As shown in the figure, a recording film 1 having a typical columnar structure has fine columnar bodies (columns) 3 having axes perpendicular to the recording film surface 2.
is composed of a collection of A gap 4 is formed between each columnar body 30 in which the columnar bodies 3 are not in contact with each other. Such a columnar recording film is observed using a scanning electron microscope.

By providing such a columnar recording film, since the gaps 4 of the columnar structure recording film have poor thermal conductivity, it is difficult to transfer heat laterally, and laser light during recording is efficiently converted into thermal energy. By efficiently increasing the temperature of the recording film, the recording sensitivity can be increased.

[Conventional technology]

The structure of a conventional magneto-optical disk is as shown in FIG.
Terbium silicon dioxide (Tb-5i (h
) film and a terbium-iron amorphous alloy thin film of a rare earth-transition element with a thickness of 90 nm.
a recording film I3 having a columnar structure of cobalt (TbFeCo);
Terbium silicon dioxide (TbS) with a thickness of 90 nm
A protective film 12 made of an i(h) film is laminated by magnetron sputtering.

As shown in item 2, in conventional magneto-optical disks, the recording film 3 has a columnar structure in order to improve recording sensitivity, and is compatible with high-speed rotation.

[Problems to be Solved by the Invention] However, when the recording film has a columnar structure, there is a problem that the recording film is easily oxidized and the signal quality and the life of the magneto-optical disk are reduced.

Even if the recording film 13 has a columnar structure and the protective film 12 is formed on it, the recording film side is very active, so that the recording film 13 exists in the protective film and at the interface between the protective film and the recording film. Oxygen and the like diffuse to the recording film side, reducing signal quality and the lifespan of the magneto-optical disk.

An object of the present invention is to solve the above problems and provide a magneto-optical disk in which the recording film is not easily oxidized even when the recording film has a columnar structure in order to improve the recording sensitivity.

A protective film is provided on the substrate, a non-columnar structure recording film, a columnar structure recording film, and a non-column structure recording film are sequentially laminated on the protective film, and a protective film is further provided as the top layer. . Alternatively, a protective film is provided on the substrate, and a columnar structure recording film and a non-columnar structure recording film are provided on the protective film and are kept as the top layer! ! It is characterized by being provided with a membrane.

In addition, the magneto-optical recording medium used in the above-mentioned magneto-optical disk has a substrate and a target for forming a protective film, a target for forming a columnar structure recording film, and a target for forming a non-columnar structure recording film arranged on a circumference of a predetermined diameter, facing each other. The magnetic field applied to the target for forming a columnar structure recording film is different from the magnetic field applied to the target for forming a non-columnar structure recording film. Magneto-optical recording media are continuously formed using different sputtering gas pressures.

[Means for Solving the Problems] The magneto-optical disk of the present invention that achieves the above object has the following features:
] The present invention protects a columnar structure recording film that is easily oxidized by sandwiching it between non-columnar structure recording films that are resistant to oxidation. This prevents oxygen from entering from the protective film side to the recording film side, and prevents oxygen from entering the protective film and the recording film. Prevents the adhesion of oxygen at the interface with the
The life of the formed magneto-optical disk can be extended.

In addition, since the substrate has a barrier effect against the intrusion of oxygen gas like the protective film, there is a gap between the protective film and the columnar structure recording film on the side that is far from the substrate and has less barrier effect against the intrusion of oxygen gas. A recording film with a non-columnar structure having a large barrier effect against oxygen gas may be provided only in this case.

In addition, as the strength of the horizontal magnetic field in the erosion region of the target (the region where the target is shaved off during the shaving process due to the application of the magnetic field of a permanent magnet) increases, the degree of columnarization of the recording film tends to decrease. As the horizontal magnetic field in the erosion region becomes smaller, the degree of columnarization of the recording film tends to increase.

Further, as the gas pressure of the ^r sputtering gas increases, the degree of columnarization of the recording film increases, and as the sputtering gas pressure decreases, the degree of columnarization of the recording film decreases.

From this, when forming a non-columnar structure recording film and a columnar structure recording film, two targets for forming a recording film with the same composition are provided side by side, and the strength of the magnetic field of the permanent magnet applied to one target is increased. Then, by decreasing the sputtering gas pressure to form a recording film with a non-columnar structure, and by decreasing the strength of the magnetic field of the permanent magnet applied to the other target and increasing the sputtering gas pressure, a non-columnar structure can be formed. A recording film and a columnar structure recording film can be formed continuously.

〔Example〕

As shown in FIG. 1, the magneto-optical disk of the present invention has a glass substrate 21 having a laser beam guide groove, and a terbium silicon dioxide (T) film for protecting the recording film from oxidation.
The protective film 22-1 made of a 90n-
It is formed by magnetron sputtering to a thickness of .

Then, on the protective film 22-1, a non-columnar structure recording film 23-1 made of an amorphous alloy of rare earth-transition metal elements such as terbium-iron-copal (TbFeCo) is formed with a thickness of 10 nm by magnetron sputtering. has been done.

Furthermore, on the non-columnar structure recording film 23-1 is a columnar structure recording film 24 made of an amorphous alloy of rare earth-transition metal elements such as terbium-iron-copal (TbFeCo).
is formed with a thickness of 70 nm, and on top of that, a rare earth metal layer made of terbium-iron-cobalt (TbFeCo) is formed.
A non-columnar structure recording film 23-2 made of an amorphous alloy of transition metal elements is formed with a thickness of Ions, and a protective film 22-2 made of a terbium-silicon dioxide (Tb-Sing) film is formed on the top layer with a thickness of 90 nm. Both thicknesses are formed by magnetron sputtering.

Further, as shown in FIG.
In the structure of the example, Tb with a thickness of 90 rv is placed on the substrate 21.
-Sin! Protective film 22-1 consisting of a film, thickness is 80 nm
A columnar structure recording film 24 made of TbFeCo with a thickness of 1
Non-columnar structure recording film 23 made of 0nsi TbFeCo
-2, a protective film 22-2 made of a Tb-5ift film having a thickness of 90 ns+ is sequentially formed by magnetron sputtering.

The method for manufacturing such a magneto-optical disk of the present invention will be described.

As shown in FIGS. 1 and 4 described above, a glass substrate 21 having a laser beam guide groove in a sputtering container 41 is used.
and a target 42 for forming a protective film, a target 43 for forming a recording film with a non-columnar structure, and a target 4 for forming a recording film with a columnar structure.
4 are placed facing each other, and a shutter 45 is installed on the target. The above three types of targets are arranged on the circumference of a predetermined diameter.

The interior of the sputtering container 41 is evacuated to a predetermined degree of vacuum by opening the valve 47 and using an exhaust pump connected to the gas exhaust pipe 46. Next, a sputtering gas consisting of ^r gas is supplied into the container from the gas supply pipe 48.

Then, the substrate is rotated so as to be positioned above the protective film forming target 42, and the shutter is opened to deposit Tb-
A protective film 22-1 made of a Sin film is formed to a thickness of 90 nm. The protective film forming target used for this film formation is a composite target of Tb and 5iO1, the sputtering gas pressure of ^r gas is 0.2 Pa, and the sputtering power is 0.2 Pa.
Step 8: Form a film. Then, the horizontal magnetic field of the permanent magnet applied to the erosion region of the target is set to 1000 e.
shall be.

Next, the substrate is rotated so that it is positioned on the target 43 for forming a recording film with a non-columnar structure. And this protective film 22
-1, a non-columnar structure recording film 23-1 of a rare earth-transition metal amorphous alloy thin film of TbFeCo is deposited to a thickness of Ion.
- to form. The target for forming a recording film with a non-columnar structure used in this film formation is a sintered alloy in which Tb, Fe, and Co are mixed at a predetermined atomic percent, and the sputtering gas pressure of Ar gas is reduced to 0.
．． 2 Pa, the sputtering power is 1 kW, and the horizontal magnetic field of the permanent magnet applied to the erosion region of the target is 7000 e.

Next, the substrate is rotated so that it is positioned on the target 44 for forming a columnar structure recording film. and non-columnar structure record 1
A TbFeCo columnar structure recording film 24 with a thickness of 70 nll is formed on the II 23-1. The target used for this film formation is a sintered alloy in which Tb, Pe, and Co are mixed at a predetermined atomic percent, the Ar gas sputtering gas pressure is 1.8 Pa, the sputtering power is 1 kTI4, and the erosion area of the target is The horizontal magnetic field of the permanent magnet to be applied is 10
Set to 00e.

Next, the substrate is rotated so that it is positioned on the target 43 for forming a recording film with a non-columnar structure. Then, on the columnar structure recording film 24, a non-columnar structure recording film 23-2 of a rare earth-transition metal amorphous alloy thin film of TbFeCo is formed with a thickness of Io.
Formed by ns. The target used for this film formation is a sintered alloy containing Tb, Fe, and Co in a predetermined atomic percent.
The sputtering gas pressure of Ar gas is set to 0.2 Pa, the sputtering power is set to -1, and the horizontal magnetic field of the permanent magnet applied to the erosion region of the target is set to 7000 e.

Next, the substrate is rotated so that it is positioned on the protective film forming target 42. And non-columnar structure recording film 23-2
A protective film 22-2 made of a Tb-Si0g film is placed on top of the
Formed to a thickness of nm.

The target used for this film formation is a composite target of Tb and Sing, and the sputtering gas pressure of Ar gas is set to 0.
The film was formed at a pressure of 2 Pa and a sputtering power of -0.8.

In the second embodiment, after forming the protective film 22-1 on the substrate 21, the step of forming the non-columnar structure recording film 23-1 is omitted and the columnar structure recording film 24 is directly formed, and then the non-columnar structure recording film 24 is directly formed. A structure recording film 23-2 and a protective film 22-2 are successively formed.

Table 1 summarizes the film forming conditions for the magneto-optical recording medium used in the magneto-optical disk of the present invention.

As shown in Table 1, in the conventional magneto-optical disk, the deterioration of signal quality (C/N) was 2 dB after 5000 hours as shown in curve g31, but according to the magneto-optical disk of this embodiment, the deterioration in signal quality (C/N) was 2 dB as shown in curve g31.
As shown in Fig. 2, no deterioration in signal quality was observed even after 500 hours had passed, and a highly reliable magneto-optical disk was obtained.

〔Effect of the invention〕

As is clear from the above description, the present invention has the effect of providing a highly reliable magneto-optical disk with a long life that does not deteriorate due to oxygen in the atmosphere even after long-term use.

The thus formed magneto-optical disk of the first embodiment of the present invention and the conventional magneto-optical disk having only a columnar structure recording film were heated at a constant temperature of 120°C and a relative humidity of 90%. We installed it in a wet tank and investigated the deterioration of signal quality. The results are shown in Figure 3 and Figure 6.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a first embodiment of the magneto-optical disk of the present invention, FIG. 2 is a cross-sectional view of a second embodiment of the magneto-optical disk of the present invention, and FIG. 3 is a sectional view of the magneto-optical disk of the present invention when left unused. A diagram of the relationship between time and C/N. Figure 4 is a schematic diagram of the device used in the magneto-optical disk of the present invention. Figure 5 is a cross-sectional view of a conventional magneto-optical disk. Figure 6 is a schematic diagram of a columnar structure recording film. It is a diagram. In the figure, 21 is a substrate, 22-1, 22-2 is a protective film, 23-1
, 23-2 is a non-columnar structure recording film, 24 is a columnar structure recording film, 31 is a characteristic curve of a conventional magneto-optical disk, 32 is a characteristic curve of a magneto-optical disk of the present invention, 41 is a sputtering container,
42 is a target for forming a protective film, 43 is a target for forming a non-columnar structure recording film, 44 is a target for forming a columnar structure recording film, 45 is a shutter, 46 is a gas exhaust pipe, 47 is a valve, and 48 is a gas supply pipe. . (/N (dB) ζ14 diagram

Claims (3)

[Claims] (1) A protective film (22-1) is provided on the substrate (21), and a non-columnar structure recording film (23-1), a columnar structure recording film (24), and a non-columnar structure recording film (23) are provided on the protective film. -2) are sequentially laminated and further provided with a protective film (22-2) on the uppermost layer. (2) In the structure of the magneto-optical disk according to claim (1), the non-columnar structure recording film (23-1) near the substrate (21) side
2. The magneto-optical disk according to claim 1, wherein the formation of the magneto-optical disk is omitted. (3) Substrate (21) and protective film formation target (42)
, a target for forming a columnar structure recording film (44) and a target for forming a non-columnar structure recording film (43) are arranged facing each other, and a magnetic field applied to the target for forming a columnar structure recording film (44) and a target for forming a non-column structure recording film are applied. The magnetic field applied to the formation target (43) is varied, and the columnar structure recording film (2
4) and the non-columnar structure recording film (23-1, 23-2)
) A method for manufacturing a magneto-optical recording medium, characterized in that the magneto-optical recording medium is continuously formed by varying the sputtering gas pressure during formation.