JP2508056B2 - 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 disk 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 their compounds are often used (Japanese Patent Publication No. 47-26897), and particularly tellurium-selenium alloys are often used ( JP-B-54-41902, JP-B-57-7919, and JP-B-57-56058).

In recent years, a semiconductor laser has been used as a laser light source in order to miniaturize a recording device. Although the oscillation wavelength of a semiconductor laser is around 8000Å, the tellurium-selenium alloy is relatively well suited to this wavelength band, and can obtain a moderate reflectance and a moderate absorptivity {Physical Status Solidide, 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.

Information is read by detecting a change in reflectance due to the presence or absence of a pit by irradiating a laser beam having a weaker power than that at the time of recording so as to pass through the pit).

[Problems to be solved by the invention]

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

For the purpose of this improvement, it has been proposed to use tellurium, selenium, and lead for the recording layer, and a recording / reproducing signal of good quality has been obtained.

The conventional optical recording medium manufacturing method is performed by a co-evaporation method of tellurium, selenium, and lead. The reason why this method is used is that although it is inferior in mass productivity, it has a more stable composition than the method in which a target made of tellurium, selenium, and lead is formed by sputtering.

The present inventor has a reason that a stable composition cannot be obtained by a method of producing a recording layer by sputtering a target made of tellurium, selenium, and lead, while performing many times of sputtering, with respect to tellurium and selenium in the target. The inventors have found that this is because the lead composition ratio is changing and have reached the present invention.

[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, a target containing tellurium and selenium as main components and a target containing lead as main components are simultaneously sputtered to form a recording layer containing tellurium, selenium, and lead as main components.

〔Example〕

 Next, examples of the present invention will be described.

One specific example of the optical recording medium manufacturing method of the present invention is 100 ° C.
A tellurium-selenium target and a lead target are simultaneously sputtered on a polycarbonate resin disk substrate with a guide groove having an inner diameter of 15 mm, an outer diameter of 13 mm, and a thickness of 1.2 mm that has been annealed for a time, and the composition of tellurium, selenium, and lead is expressed in atomic percentages. With a thickness of 75: 19: 6, a thickness of about 250Å was formed. Then, an optical recording medium was prepared by annealing at 95 ° C. for 1 hour.

The reflectance of this optical recording medium at a wavelength of 8300Å upon incidence on the substrate was measured and found to be about 34%. A semiconductor laser beam with a wavelength of 8300Å enters through the substrate and 1.6μ on the recording layer.
Squeezing to about mφ, medium linear velocity 5.65m / sec, recording frequency 3.77
Recording was performed under the conditions of MHz, recording pulse width 70 msec, recording power 7.0 mW, and reproduced at 0.5 mW. The carrier-to-noise ratio (C / N) with a bandwidth of 30 KHz was as good as 48 dB.

When a large number of optical recording media were similarly prepared by performing sputtering a number of times and evaluated, the composition ratio did not change, and the reproducibility of the recording / reproducing characteristics was good.

The thickness of the recording layer is preferably in the range of 100Å to 1000Å,
Selenium content is 2% or more in terms of atomic number
The range of less than 40% is desirable, and the content of lead is preferably 1% or more and less than 20% in terms of atomic number.

A trigger layer may be provided between the recording layer and the substrate,
A protective film may be provided on the recording layer to such an extent that the recording / reproducing characteristics are not hindered.

〔The invention's effect〕

The optical recording medium manufacturing method of the present invention has an effect that an optical recording medium having good signal quality can be manufactured with high mass productivity and good reproducibility.

[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 sputtering container,
A first target containing tellurium and selenium as main components and a second target containing lead as main components are simultaneously sputtered to form a recording layer containing tellurium, selenium, and lead as main components. Optical recording medium manufacturing method.