JPH046559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical information recording medium in which information is recorded by forming holes or recesses in a recording layer by irradiation with an energy beam such as light or heat.

Tellurium (Te) has traditionally been used as a recording thin film in optical information recording media in which a thin film layer formed on a substrate is irradiated with an energy beam to form a bit string corresponding to the signal to be recorded. It is known. Te thin film is a material that can form desired bits with the lowest energy and is extremely effective as a highly sensitive material for this type of application. Sensitivity here is defined as the energy (mJ/cm ² ) required to form a bit per unit area.

However, if Te is left in the atmosphere,
When used as a recording film that quickly becomes transparent when oxidized by oxygen or moisture, the film thickness is extremely thin at around 700 mm, so the film's sensitivity deterioration and output decrease due to increased transparency caused by oxidation of the bismuth thin film. Significant. That is, when the film is oxidized, the melting and evaporation temperature increases, resulting in deterioration of sensitivity, and since the film becomes transparent, the reflectance or transmittance no longer responds sensitively to the presence or absence of bits on which information is recorded. For example, if left in an atmosphere of 70°C and 85% relative humidity, approximately 5
Sensitivity decreases by approximately 20% over time, and by approximately 50% in approximately 15 hours. For this reason, various preventive measures have been taken to prevent oxidation of the Te film. The most effective method would be to cover it with an inorganic glass material, but it has not been put to practical use because the process is complicated and expensive. Organic resins, such as transparent plastics, are cheaper, have half the thermal conductivity of glass, and double the sensitivity, so one of the current priorities is how to make the best use of plastics. There is. Plastic has a definite flaw here. In other words, it allows oxygen and moisture in the atmosphere to pass freely through it, meaning that it cannot be used as a substrate for the above-mentioned Te thin film.

The present invention has been made in view of this problem, and an object of the present invention is to provide a method for manufacturing an optical information recording medium that can obtain an optical information recording medium with high sensitivity and long life while using an organic resin base. With the goal.

This invention uses tellurium as a target in a method for manufacturing an optical information recording medium in which a recording film is formed on a substrate, the recording film is irradiated with an energy beam, and a deformed portion is formed in the recording film to record information. ,
A thin film mainly composed of tellurium containing 5 to 40 at% carbon, 5 to 40 at% hydrogen, and 5 to 30 at% nitrogen by sputtering in a mixed gas of nitrogen gas and a gas containing carbon and hydrogen. This is a method of manufacturing an optical information recording medium, which is characterized in that a recording film is formed by forming a recording film on a substrate.

The mixing ratio of the gas mixture containing carbon and hydrogen and nitrogen gas used in the present invention may be appropriately determined depending on the content ratio of carbon, hydrogen, and nitrogen in the desired tellurium-based thin film. It is not limited.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of the present invention. In the figure, reference numeral 1 denotes a substrate, and in this example, an acrylic plate, which is also a type of synthetic resin, was used. However, any other type of plastic plate or glass plate has the same effect and may be selected as appropriate depending on the information recording/reading method used. 2 is a low melting point metal or metal alloy film for information recording containing C, N, and H, and its thickness must be thick enough to obtain sufficient light reflectance and thin enough not to impair sensitivity. Therefore, a suitable thickness is about 200 to 1 μm. For recording information including C, N and H
The Te thin film 2 is obtained by sputtering Te as a target in a gas containing C and H, such as a mixed gas of CH ₄ gas and N ₂ . here
The contents of C, H, and N in the Te film can be freely controlled by the mixing ratio of N ₂ and CH ₄ and the applied high-frequency power. For example, at a mixing ratio of N ₂ /CH ₄ = 1, the content of
When RF (13.56MHz) power of W/ ^cm2 is applied between the Te target and the substrate, about 20 at.% C and about 10
A film containing atomic % of H and about 10 atomic % of N can be formed.

The film thickness can be obtained by varying the sputtering time. The optical constants of the film vary depending on the content of C, H, and N, but there are limits to the reflectance and attrition coefficient when it is used for information recording, and our experimental results indicate that the film cannot be used under the above deposition conditions. The best membrane was obtained at a membrane pressure of about 1000. The film produced under these conditions is amorphous, and compared to a polycrystalline Te film, the edges around the bit in the recorded state are smoother, and the noise level when reading information can be suppressed to a lower level.

FIG. 2 is a diagram comparing the deterioration of sensitivity over time in an atmosphere of 70° C. and a relative temperature of 85% between the conventional single Te and the present invention.

The deterioration in sensitivity in this figure is expressed as a change in the reciprocal of the energy required for recording relative to the initial value, and shows the case where both the conventional recording film made of Te alone and the recording film according to the present invention are formed on an acrylic substrate. .

As can be seen from this figure, in the case of a recording film made of Te alone, the sensitivity deteriorates over time as shown by A in the figure. This is because local transparent areas (stains) occur over time, and after about 170 hours, the entire surface deteriorates.

On the other hand, containing C, H and N according to the present invention
In the case of the Te thin film, as shown by B in the same figure, even after 1000 hours, no stains like those seen with the Te thin film were observed, and the sensitivity always remained almost constant.
It can be seen that a long life has been achieved.

As described above, the recording medium using the Te thin film containing C, H, and N according to the present invention can provide excellent sensitivity and a very long life. however,
For films with a C content of 5 at% or less, no significant difference from the Te film was observed, and for films with a C content of 40 at% or more, a decrease in sensitivity was observed. Furthermore, films with an H content of 5 at% or less resulted in a decrease in sensitivity, and films with an H content of 40 at% or more resulted in a decrease in reflectance of the film, making them unsuitable as thin films for recording. Also, 5 atomic%
No significant relationship with the Te film was observed at N contents below, and peeling of the film was observed at 30 atomic % or more.

The above example describes a thin film formation method using reactive sputtering in N ₂ gas and CH ₄ gas.

Therefore, C and H do not exist completely separately in the film. _CH4 gas is produced by electrolytic dissociation
It is decomposed sequentially into CH ₃ (radical), CH ₂ (radical), CH (radical), and then C and H radical groups, and Te atom intervenes, and any n group of (CHm) and Te and polymerize to form a net. Therefore, the formed film is amorphous, which can be concluded from the results of Raman scattering, differential thermal analysis, infrared absorption analysis, etc. Due to this semi-organic amorphous structure composed of Te, C, H, and CmHn, it has the same high sensitivity characteristics as a single Te film, and since there are no tangling ponds (unbonded groups) that become oxidized, it has long life characteristics. It will have .

Here, the role of N atoms contributes to high sensitivity of the film.
The substance TeN is explosive. Therefore, a TeN film can form bits with less laser beam power than a single Te film. For example, 20 atomic% Na,
Te films have a short lifetime due to their microcrystalline nature, which exhibits about twice the sensitivity of unit Te films. With the amorphous structure of CmHn and the explosive nature of N, we were able to create a film with unprecedented high sensitivity and long life.

The optical information recording medium of the present invention has the property of being able to form fine patterns as desired because it acts sensitively on laser light with a diameter of 1 μι or less, and other uses are also possible by taking advantage of this property. For example, it can be used as a photoresist used for ICs. Current photoresists require a wet process, but with the film of the present invention,
It has the great advantage of requiring only a dry process.
Additionally, it can be used as a protective layer for various parts due to its resistance to water and moisture. For example, as a protective film for Te film, which is a conventional information recording film, and as a protective layer for ICs, etc.
As a diode p-n junction surface protective layer, etc.
It can be used as an insulating layer for multilayer wiring for ICs, an electrical insulating layer, etc.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional configuration diagram of an optical information recording medium obtained by an example of the present invention, and FIG. 2 is a comparison of the lifespan of the optical information recording medium shown in FIG. 1 and a conventional recording medium. It is a diagram. 1...Substrate, 2...Te-C-H-N film.

Claims (1)

[Claims] 1. In a method for manufacturing an optical information recording medium, in which a recording film is formed on a substrate, the recording film is irradiated with an energy beam, and information is recorded by forming a deformed portion on the recording film, tellurium is used as a target, and methane gas and By sputtering in a mixed gas of nitrogen gas, a thin film mainly composed of tellurium containing 5 to 40 atom% carbon, 5 to 40 atom% hydrogen, and 5 to 30 atom% nitrogen is formed on a substrate and recorded. A method for producing an optical information recording medium, characterized in that it is a film.