JPS6363152A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To improve weatherability, sensitivity and signal quality by providing a tellurium-selenium-nitrogen layer into a recording layer by using a material contg. tellurium and selenium as a target and executing sputtering in a gas contg. gaseous nitrogen and gaseous hydrogen. CONSTITUTION:The layer essentially consisting of tellurium, selenium and nitrogen is provided in the recording layer 21 by using the material contg. tellurium and selenium as the target and executing the sputtering in the gas contg. the gaseous nitrogen and gaseous hydrogen. The thickness of the tellurium-selenium- nitrogen layer is preferably in a 100-1,000Angstrom range in terms of recording and reproducing characteristics and the range of 2-50atom% is preferable for the content of the selenium in terms of the recording and reproducing characteristics and weatherability. The content of the nitrogen is preferably 2-20atom% in terms of the recording and reproducing characteristics and weatherability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] - The present invention relates to a method of manufacturing an optical recording medium on which information can be recorded and reproduced using laser light.

[Prior Art] Optical disk memories have excellent characteristics as large-capacity recording devices because of their high recording density.

Tantalum and lead were first used as optical recording medium materials (Science 154.15
50°1966)). Since then, various materials have been used, but chalcogen elements such as tellurium (Te) or their compounds are often used (Japanese Patent Publication No. 47-26
In particular, tellurium-selenium alloys are often used (Japanese Patent Publications No. 41902/1982, 7919/1989, and 56058/1989).

In recent years, in order to downsize recording devices, semiconductor lasers have been used as laser light sources. Semiconductor lasers have an oscillation wavelength of around aooo, but tellurium-selenium alloys are relatively well suited to this wavelength range, and can provide moderate reflectance and moderate absorption (physica status solidi). , 5tat.

sol, 7.189.1964)).

An optical recording medium using this tellurium-selenium alloy as an optical recording layer has a structure as shown in Figure 1.
-1-f-mo4- fit flea C'1l-IT next position +
? 211.11. Jwl.

A recording layer 21 made of a carbon-based alloy is provided. The recording laser beam is focused and irradiated onto the recording layer 21 through the substrate 1,
A pit 22 is formed. The substrate 1 is made of synthetic resin such as polycarbonate, polyolefin, polymethylpentene, acrylic, or epoxy resin, or glass, and is usually guided so that pits are recorded concentrically or spirally at regular intervals with high accuracy. A groove is provided.

When light enters a groove with a width similar to the diameter of the laser beam, the light is diffracted, and as the beam center shifts from the groove, the spatial distribution of the intensity of the diffracted light changes.This is detected and the laser beam is directed to the center of the groove. The servo system is configured as follows. The width of the groove is usually 0.3 to 1.3 Aun, and the depth of the groove is set within the range of 1712 to 174 of the laser wavelength used. A servo system is similarly configured for condensing light. Information is read by irradiating a laser beam with a weaker power than during recording so as to pass over the pits, and detecting changes in reflectance caused by the presence or absence of pits.

[Problems to be Solved by the Invention] However, optical recording media using a tellurium-selenium alloy layer as a recording layer do not satisfy all of weather resistance, sensitivity, and signal quality.

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

[Means for Solving the Problems] The present invention provides a method for manufacturing an optical recording medium, which comprises forming a recording layer on a substrate, a portion of which is selectively removed by a laser beam to record information. Optical recording characterized in that at least a layer containing tellurium, selenium, and nitrogen as main components is provided in the recording layer by sputtering a substance containing tellurium and selenium as a target in a gas containing nitrogen gas and hydrogen gas. This is a method for producing a medium.

The thickness of the layer whose main components are tellurium, selenium, and nitrogen (hereinafter referred to as the tellurium-selenium-nitrogen layer) is from 100 to i
From the viewpoint of recording and reproducing characteristics, the selenium content is preferably in the range of 2 to 5 atomic percent.
A range of 0% is desirable from the viewpoint of recording/reproducing characteristics and weather resistance, and a nitrogen content of 2% or more and less than 20% in terms of atomic percent is desirable from the viewpoint of recording/reproducing characteristics and weather resistance. In addition, the composition ratio of elements in the tellurium-selenium-nitrogen layer naturally depends on the composition ratio of the target and the gas partial pressures of nitrogen (N2) gas and hydrogen (N2) gas, but it also depends on the size of the sputtering equipment. The surface area of the sputtering chamber, etc.) depends on the sputtering time, etc., so in order to obtain the desired recording film composition, N2 gas and N2 gas must be used for each sputtering device.
It is desirable to set the gas partial pressure etc. appropriately.

The layer mainly composed of tellurium, selenium, and nitrogen contains lead, antimony, arsenic, sulfur, tin, germanium, thallium, phosphorus, cadmium, indium, gallium, zinc,
At least one element selected from the group consisting of bismuth, aluminum, copper, silver, magnesium, tantalum, gold, palladium, and cobalt may be added. in this case,
In some cases, the shape of the pit can be improved. However, the amount added is preferably less than 20 percent in terms of atomic percent.

The sputtering gas may be N2 gas or only N2 gas, but from the viewpoint of stability of discharge and film formation, a mixed gas with an inert gas is preferable. Further, other gases may be mixed into the mixture.

At least one layer formed of an oxide, nitride, fluoride, carbide, sulfide or boride may be provided between the tellurium-selenium-nitrogen layer and the substrate. In this case, there is a greater margin for recording power fluctuations, and tracking and focusing servo may become more stable.

Further, as the substrate, commonly used materials such as synthetic resins such as polycarbonate, polyolefin, polymethylpentene, acrylic and epoxy resins, and glass are used.

[Example] Examples of the present invention will be described below.

15mm inner diameter, annealed at 100'C for 2 hours.
Tellurium (Te) and selenium were sputtered onto a polycarbonate resin disk substrate with a guide groove of 130 m in outer diameter and 1.2 mm in thickness by magnetron sputtering a tellurium-selenium alloy target with a mixed gas of argon (Ar>, N2, and N2). (
The ratio of Se) to nitrogen (N) is 85:9 in atomic percent
Forming a tellurium-selenium-nitrogen layer of about 240 layers thick,
Thereafter, it was stored for 12 hours in an environment with a temperature of 85° C. and a relative humidity of 90% to produce an optical recording medium. When the reflectance of this optical disk at a wavelength of 8,300 degrees when incident on the substrate was measured, it was approximately 26%. Semiconductor laser light with a wavelength of 8300A is incident through the substrate and 1.61J! rI
Recording was performed under the following conditions: medium linear velocity of 5.65 m/sec, recording frequency of 3.778 H2, recording pulse width of 70 nsec, recording power of 6.0 mW, and reproduction at 0.7 mW. The carrier-to-noise ratio (C/N) with a bandwidth of 30 kHz was as good as 48 dB.

After this optical disc was stored in a high temperature and high humidity environment of 70'C 180% for 60 hours, the above characteristics were examined, but there was no change, and it was confirmed that the optical recording medium had excellent weather resistance.

[Effects of the Invention] As explained above, according to the method of the present invention, it is possible to manufacture a stable optical recording medium with good weather resistance, high sensitivity, and good signal quality.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing an example of an optical recording medium. 1... Board 21...Recording layer 22...Pit

Claims (1)

[Claims] (1) A method for manufacturing an optical recording medium comprising forming a recording layer on a substrate, a portion of which is selectively removed by a laser beam to record information, wherein the recording layer contains tellurium and selenium. A method for producing an optical recording medium, which comprises using a substance as a target and sputtering in a gas containing nitrogen gas and hydrogen gas to provide at least a layer containing tellurium, selenium, and nitrogen as main components.