JP2508053B2 - Optical recording medium manufacturing method - Google Patents

Description

The present invention relates to an optical recording medium manufacturing method, and more particularly to an optical recording medium manufacturing method for manufacturing an optical recording medium capable of recording and reproducing information by laser light. Regarding

[Conventional technology]

In general, an optical disc memory that records and reproduces information on a medium by laser light has a high recording density and thus has an excellent feature as a large-capacity recording device. Tantalum and lead were first used as materials for this optical recording medium {Science 154, 1550, 1966)}. Since then, various materials have been used, but chalcogen elements such as tellurium or these compounds are often used (Japanese Patent Publication No. 47-26897), and especially tellurium-selenium alloys are often used ( Japanese Patent Publication No. 54-41902, Japanese Patent Publication No. 5
7-7919, Japanese Patent Publication No. 57-56058).

In recent years, a semiconductor laser has been used as a laser light source in order to miniaturize a recording device. The semiconductor laser is oscillated wavelength is around 8000 Å, tellurium - selenium alloys This also relatively well suited to the wavelength band, appropriate reflectance and moderate absorption rate is obtained {Physica-status-Soridai, 7, 189,1964 (phys · stat · sol. 7, 189,1964)}.

An example of an optical recording medium manufactured by the present invention using the tellurium-selenium alloy as an optical recording layer and a conventional optical recording medium manufacturing method has a structure as shown in FIG.

That is, a recording layer 21 made of tellurium-selenium alloy is provided adjacent to the substrate 1. The recording laser beam is condensed and irradiated on the recording layer 21 through the substrate 1 to form pits 22. As the substrate 1, synthetic resin such as polycarbonate, polyolefin, polymethylpentene, acryl, epoxy resin, or glass is used. Usually, the substrate 1 is formed so that pits are concentrically or spirally accurately recorded at regular intervals. A guide groove is provided.

When light enters a groove with a width of about the laser beam diameter, the light is diffracted, and the spatial distribution of the diffracted light intensity changes as the beam center shifts from the groove, so this is detected and the laser beam is incident on the center of the groove. The servo system is configured as follows. The width of the groove is usually 0.3 to 1.3 μm, and the depth of the groove is set in the range of 1/20 to 1/4 of the laser wavelength used.
A servo system is similarly configured for focusing.

Reading of information is performed by irradiating a laser beam having a lower power than at the time of recording so as to pass over the pits, thereby detecting a change in reflectance caused by the presence or absence of the pits.

[Problems to be solved by the invention]

However, with the tellurium-selenium alloy film, a good quality recording / reproducing signal could not be obtained.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method of manufacturing an optical recording medium that has good weather resistance, high sensitivity, and can obtain a good quality signal. And

[Means for solving problems]

An optical recording medium manufacturing method of the present invention is a method for manufacturing an optical recording medium having at least a substrate and a recording layer formed on the substrate, which is partially removed by laser light to record information. Then, by passing a vapor containing tellurium and selenium through a nitrogen gas or a mixed gas containing the nitrogen gas that has been turned into plasma by high-frequency power,
It is configured to produce a recording layer containing tellurium, selenium, and nitrogen as main components.

[Action]

By using tellurium, selenium, and nitrogen as the main components of the recording layer, an optical recording medium having good weather resistance, high sensitivity, and good signal quality can be obtained. The reason why this optical recording medium can obtain a signal with high sensitivity and good quality is that the formation of small holes, which is the initial stage of pit formation recording, is caused by the formation of a compound of nitrogen and chalcogen element in the film. This is because the irradiation is performed with an extremely low recording power.

〔Example〕

 Next, examples of the present invention will be described.

One specific example of the method for producing an optical recording medium of the present invention is as follows. A polycarbonate resin disk substrate with an inner diameter of 15 mm and a thickness of 1.2 mm, which is annealed at 100 ° C. for 2 hours, is placed in a vacuum apparatus and 5 × 10 ⁻⁶ Torr. Exhausted below. As an evaporation source, tellurium was placed in the first resistance heating boat and selenium was placed in the second resistance heating boat. By introducing a mixed gas of nitrogen and argon and applying high frequency power of 13.56 MHz to the high frequency coil to generate plasma, tellurium and selenium are simultaneously vaporized from each boat and passed through the plasma. , A part of tellurium and selenium was nitrided to form a layer containing tellurium, selenium and nitrogen as a main component with a ratio of tellurium to selenium and nitrogen of 76: 19: 5 on the substrate in a thickness of 260Å. . After that, the temperature is 85 ℃,
An optical recording medium was prepared by storing it in an environment of 90% relative humidity for 12 hours. The reflectance of this optical recording medium at a wavelength of 8300Å upon incidence on the substrate was measured and found to be about 29%. Wavelength 8300Å
The semiconductor laser light of is incident through the substrate, and 1.
Squeezing to about 6 μmφ, medium linear velocity 5.65 m / sec, recording frequency
Recording was performed under the conditions of 3.77 MHz, recording pulse width 70 nsec, recording power 7.5 mW, and reproduced at 0.7 mW. The carrier-to-noise ratio (C / N) with a bandwidth of 30 KHz was as good as 48 dB.

This optical recording medium is used in an environment of high temperature and high humidity of 70 ° C and 80%.
After storage for a period of time, the above characteristics were examined, but there was no change, and it was confirmed that the optical recording medium had excellent weather resistance.

The thickness of the recording layer is preferably in the range of 100Å to 1000Å from the viewpoint of recording / reproducing characteristics, and the content of selenium is preferably in the range of 2% to less than 40% in terms of atomic number from the viewpoint of recording / reproducing characteristics and weather resistance. From the viewpoint of recording / reproducing characteristics and weather resistance, the content of is preferably 2% or more and less than 20% in terms of the number of atoms.

〔The invention's effect〕

The optical recording medium manufacturing method of the present invention has an effect that an optical recording medium having good weather resistance, high sensitivity, and good signal quality can be manufactured.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an example of an optical recording medium manufactured by the present invention and a conventional optical recording medium manufacturing method. 1 ... Substrate, 21 ... Recording layer, 22 ... Pit.

Claims (1)

(57) [Claims] 1. A substrate is placed in a gas atmosphere containing at least nitrogen gas plasmatized by high-frequency power, vapor containing tellurium and selenium is passed through the gas atmosphere, and tellurium and selenium are deposited on the substrate. A method for producing an optical recording medium, which comprises producing a recording layer containing nitrogen as a main component.