JPS60125950A - Optical information recording medium and its production - Google Patents

Abstract

PURPOSE:To obtain a recording film having a long life without oxidation even if the film is stored for a long period of time by incorporating nitrogen and hydrogen into a photomagnetic recording film. CONSTITUTION:A base plate 1 is installed on a counter electrode 16 in common use as a base plate holder and thereafter the inside of a vacuum vessel 11 is evacuated. A gaseous mixture of gaseous Ar and nitrogen, hydrogen, ammonia, etc. is then introduced into the vessel through a gas introducing hole 13. High- frequency electric power is impressed from an electric power introducing terminal 15 to start electric discharge. A rare earth-transition metal alloy target is sputtered by the plasma mixture composed of the gaseous Ar and the gaseous nitrogen and hydrogen to form a recording film 4 consisting of the rare earth transition metal, nitrogen and hydrogen on the plate 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an optical information recording medium, and particularly to an optical information recording medium that has a long service life.

[Technical background and problems of the invention]

Typical conventional general perpendicular magneto-optical recording media are those shown in FIG. 1 and FIG. 2.

That is, in FIG. 1, 1 is an organic resin such as acrylic;
Alternatively, it is a substrate made of glass or the like. 2 is a recording film having magnetic anisotropy perpendicular to the substrate surface. The recording film is Gd.

Rare earth metals such as Tb, Dy, and Ho, and Fe, Co, and Ni
Amorphous alloy films consisting of transition metals such as

Although rare earth transition metal amorphous alloy films have several advantages, such as being relatively easy to form and exhibiting good magneto-optical properties, they are extremely susceptible to oxidation when stored in air. There is a drawback.

That is, for example, when a TbFe film with a thickness of 1000× formed on a glass substrate is left in the atmosphere, almost the entire film surface becomes transparent due to the formation of oxides within a few months. Naturally, the transparent recording film cannot be used as a recording film, and the recorded information will also be lost.

The film shown in FIG. 2 has been proposed for the purpose of improving the drawbacks of such a rare earth transition metal amorphous alloy film, and is a film in which a protective film 7i#3 is laminated on the recording film 2 as an anti-oxidation layer. As the protective layer 3, an oxide thin film such as SIO formed by a vapor deposition method or a sputtering method, or an organic resin thin film formed by a spinner method or the like is usually used. However, it is extremely difficult to prevent oxidation of the recording film with such a protective film according to the prior art. This means that the protective film has a thickness of 1 μm.
This is because oxygen molecules in the atmosphere can pass through the protective film relatively easily because the formed protective film is not sufficiently dense. If an organic resin is used for the substrate 1, the recording film may be oxidized by oxygen molecules passing through the substrate.

[Purpose of the invention]

The purpose of the present invention is to eliminate the shortcomings of the prior art, and to provide a rare earth/transition metal amorphous alloy film that does not become regenerated even when stored in the atmosphere for a long period of time (a rare earth/transition metal amorphous alloy film with a long lifespan that can be put to practical use). An object of the present invention is to provide an optical information recording medium used as a recording film and a method for manufacturing the same.

[Summary of the invention]

The optical information recording medium according to the present invention is characterized in that a rare earth/transition metal amorphous alloy film contains hydrogen and hydrogen.

〔Effect of the invention〕

According to the present invention, since the oxidation resistance of the recording film itself is significantly improved, there is no need for measures that complicate the manufacturing process of the recording medium, although the effect of laminating protective films is small. , it is possible to obtain an optical information recording medium with an extremely long life due to its extremely simple configuration.

[Embodiments of the invention]

FIG. 3 is a diagram showing an example of an apparatus for implementing the present invention. In Figure 3, 11 is a vacuum container, 12 is an exhaust hole to the X pump, 13 is a gas introduction hole for sputtering, 14 is a target, 15 is a power introduction terminal, 16 is a grounded counter electrode, and 16 is a grounded counter electrode. The holder is soaking in water.

An example of the method for manufacturing the information recording medium of the present invention will be explained based on FIG. After installing the cutting board on the opposite turtle hood that also serves as a substrate holder, the empty container 11 is heated to 10-' Torr.
Exhaust to a certain extent. After that, a mixed gas of Ar gas, nitrogen, hydrogen, ammonia, etc. is introduced through the gas introduction hole at 10-8
What is the range of ~10-'' Torr?The discharge is not stable even if the introduction pressure is lower than 10-'' Torr or higher than 10-1 Torr.The mixing ratio of Ar gas, nitrogen, and hydrogen gas is It is set to a predetermined value depending on the layer containing nitrogen and hydrogen contained in the recording film.

Next, from the power introduction terminal 15, for example, 13.56MHz
Apply high frequency power to start discharging.

A rare earth/transition metal alloy target is sputtered with a mixed plasma of Ar gas, nitrogen, and hydrogen gas, and a recording film made of rare earth/transition metal, nitrogen, and hydrogen is formed on the base.

In order to incorporate nitrogen and hydrogen into the recording film, it is extremely effective to generate a plasma of a mixed gas of Ar gas and a gas containing violet and hydrogen as described above. It is possible to uniformly contain nitrogen and hydrogen into the recording film, and by changing the mixing ratio of Ar gas and hydrogen-containing gas, the amount of nitrogen and hydrogen contained in the recording film can be arbitrarily changed. This is because it is extremely easy.

A gas containing nitrogen and hydrogen is a mixture of N, gas and H at a predetermined ratio! It may be used in combination with a gas (a compound gas consisting of nitrogen and hydrogen such as NH8°N, H, etc.).

The contents of nitrogen and hydrogen are determined in consideration of the oxidation resistance and magnetic properties of the recording film. As the nitrogen and hydrogen contents increase, the oxidation resistance improves, but the magnetic properties deteriorate. The total content of nitrogen and hydrogen is 20 atomic
% or less.

If more than 20 atomic% of nitrogen and hydrogen are contained, the minute magnetic domains corresponding to the recorded information, called bits, become unstable against heat due to a decrease in the saturation magnetization of the recording film, a decrease in the perpendicular magnetic anisotropy constant, etc. Become. Or, the refractive index of the recording film changes, the amount of absorption of the laser beam used for recording and reproduction decreases, and good recording and reproduction is no longer possible. This is because the favorable properties of the membrane are lost.

ij of the present invention: An example of a recording medium is shown in FIG. In FIG. 4, 1 is a substrate and 4 is a recording film.

Example-1 Gd, T b, llFe produced by arc melt method
,. A recording film was manufactured by sputtering an alloy target using plasma using a mixed gas of Ar gas, NH, and gas.

The mixing ratio of Ar gas and NH gas is the pressure ratio NH, /(A
r 10NHs) of 0.1, 0.2.0.4,
0.6.0.8.1.0. The pressure during discharge is 2
10'-”Torr, high frequency power is 300W (!:j
,Ta. The board is Yuning, thickness Q, 13mm? 705
A 9-inch glass plate was used. The discharge time was varied so that the thickness of the recording film formed was 1000 A at any mixing ratio. In the case where the CH4/(CH4+A r ) value was 1.0, the recording film peeled off from the substrate during storage in the atmosphere for 1 to 2 days after formation.

The transmittance and reflectance of the recording medium manufactured in this example at a wavelength of 83ooX were measured. Absorption rate was calculated from the measured values of transmittance and reflectance using the following formula.

Absorption rate-1-reflectance-transmittance The relationship between the calculated absorption rate and the mixing ratio of Ar gas, NH, and gas is shown at 21' in FIG. It can be seen that recording media with a mixing ratio of up to 0.8 exhibit good absorption rates of 0.3 or higher. The broken line indicated by 22 in FIG. 5 shows the relationship between the absorption rate and the mixing ratio after processing the recording medium produced in this example at 70° C. and 85 SRH for 15 days.

It can be seen that the oxidation resistance is significantly increased by containing nitrogen and hydrogen.

Comparative Example-1 As a comparative example, the same Gd15TbIIIF as in Example-1 was used.
A recording film with a thickness of 100 OA was formed on a glass substrate by sputtering an e7G target in pure Ar gas. The recording medium of this comparative example showed a high absorption rate of 0.5. However, after being left at 70° C. and 854 RH for 8 days, the entire surface of the film became transparent.

Example-2 Gd. Fe, Co, alloy target with Ar gas and N.

A recording film was manufactured by sputtering with plasma using a mixed gas of H, H, and gas. Pressure ratio (Nt + Ht) / (
The value of A r +Nt +Ht) was set to 0.3. Ht
The value of /Nt was set to 4. The substrate is a 7059 glass plate with a thickness of Q, 8 mm.

The thickness of the recording film was 800. The absorption coefficient of the recording medium of this example at a wavelength of 8300A showed a good value of 0.45. The recording medium of this example was 70”C, 854R.
After treatment under H conditions for 20 days, the absorption rate was measured.

The absorption rate after treatment was 0.40, with almost no decrease observed.

Comparative Example-2 As a comparative example, the same odfio"ello as in Example-2 was used.
cot.

An alloy target was sputtered in pure Ar gas to form a recording film with a thickness of 100 OA on a glass substrate.

The recording medium of this comparative example was
After treatment for several days, the entire surface of the film became transparent.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing conventional optical information recording media, FIG. 3 is an explanatory diagram of an apparatus for implementing the present invention, and FIG. 4 is an embodiment of the recording medium of the present invention. Cross-sectional view shown, No. 5
The figure shows the changes caused by an accelerated deterioration test of the absorption rate of the recording medium of the present invention at a wavelength of 8300A. 1... Substrate, 4... Recording film, 11... Vacuum container,
12... - Exhaust hole to vacuum pump, 13... Gas introduction hole, 14... Target, 15... Power introduction terminal,
16...Counter electrode. Representative Patent Attorney Kensuke Chika (and 1 other person) Figure 1 Figure 3 Figure 4 Figure 5 ↑ NHJNHstβr)

Claims (2)

[Claims] (1) It has an axis of easy magnetization in a direction perpendicular to the substrate surface. An optical information recording medium on which a magneto-optical recording film is formed, in which information is recorded and reproduced by irradiation with a light beam, wherein the magneto-optical recording film contains nitrogen and hydrogen. . (2) The magneto-optical recording film is amorphous, consisting of rare earth metals such as Gd, Tb, Dy, and Ho, and transition metals such as Fe, Co, and Ni. (3) It has an axis of easy magnetization perpendicular to the substrate surface. In the method for manufacturing an optical recording medium on which a magneto-optical recording film is formed, in which information is recorded and reproduced by irradiation with a source beam, a method for containing nitrogen and hydrogen in the optical recording film includes:
1. A method for producing an optical information recording medium, comprising depositing rare earths and transition metals on a substrate by sputtering, vapor deposition, or the like while discharging in a gas containing nitrogen and hydrogen.