JPS62154241A - Medium for optical recording - Google Patents

Abstract

PURPOSE:To improve stability with lapse of time, C/N and pit shape by executing reactive sputtering with a metal contg. Te as target material in a gaseous mixture composed of a reactive gas consisting of >=1 kinds of inorg. or org. fluorides and gaseous Ar thereby forming a deposited film contg. Te on a substrate. CONSTITUTION:The material for the substrate of a recording medium is exemplified by glass, plastics such as acrylic resin or metals such as aluminum and the thickness thereof is generally about 1-1.5mm. The metallic compd. deposited film is formed by a reactive sputtering method on such substrate. The alloy contg. Te is used as a target material and glow discharge is executed into a vacuum vessel into which the gaseous mixture composed of the gaseous argon (Ar) and the reactive gas consisting of >=1 kinds of the org. and inorg. fluorides is introduced to form the metallic compd. deposited film contg. Te on the substrate. The substrate temp. is maintained from room temp. to < softening point of the substrate. The thickness of the deposited film formed by sputtering is usually about 50Angstrom -1mum and more preferably about 200-1,000Angstrom .

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to optical recording media. Specifically, the invention relates to an optical recording medium in which recording is performed by irradiating a laser beam to locally heat the area and forming holes, depressions, or projections in the heated area.

(Prior art and its problems) A thin film formed on a substrate is irradiated with a laser beam,
It is conventionally known to use 5Te as an optical recording medium hardened to form holes (bits). To
exhibits high sensitivity in recording by the above method due to its low melting point and low thermal conductivity. However, Te has the problem that it is easily oxidized, and when it is oxidized, it becomes transparent and recording is no longer possible.

The above-mentioned recording medium may be manufactured by the A-vapor deposition method or the ion blating method, but generally, the sputtering method is often used because of the good controllability during film formation.

The present inventors used Ar f sputtering gas and 're
We investigated fcTe thread alloy recording media using an alloy containing FC as a target material. Furthermore, it was confirmed by transmission electron microscope images, and it was found that the pit shape and recording sensitivity were poor due to this, and noise during signal reproduction caused by the laser beam was involved. Further, the reflectance of the deposited film having the above-mentioned crystal grains at a temperature of 70°C and a relative humidity of g
In the accelerated test of S name, it was revealed that the initial reflectance increased to nearly 3 times the initial reflectance within -q hours, and the stability over time was extremely stable at 6V.

(Means for Solving the Problem) Based on these results, the inventors of the present invention further investigated the problem, and found that by sputtering an alloy; l-get by mixing fluoride gas into the sputtering gas. acrylic,
The inventors of the present invention discovered that it is possible to obtain an optical recording medium on a polycarbonate substrate that has no crystal grains or grain boundaries, has good sensitivity and pit shape, has no uneven recording sensitivity due to location, and has excellent stability over time. reached.

That is, the gist of the present invention is to perform reactive sputtering on a substrate using a metal containing τθ as a target material in a mixed gas of Ar gas and a reactive gas consisting of one or more organic or inorganic fluorides. Contains To in
An optical recording medium is provided in which four films are formed.

(Structure of the invention) The present invention will be explained in detail below.

First, as the substrate of the recording medium according to the present invention, plastics such as glass, acrylic resin, polycarbonate resin, etc.
Alternatively, metals such as aluminum can be used, and the thickness thereof is generally about 8 to 10 cm.

In the present invention, a metal compound deposited film is formed on this substrate by a reactive sputtering method.

In the present invention, a glow discharge is performed in a vacuum container into which a mixed gas of argon (Ar) gas and 6 reactive gases selected from one or more types of inorganic fluorides is introduced, using an alloy containing Tot- as a target material. Depending on what you do, on the board 1
A metal compound deposited film containing cTa is formed. Glow release
When Vc is applied, a conventional method such as a high frequency method or a direct current method can be used, and radicals and ion mixtures are generated.

The substrate temperature is maintained between room temperature and below the softening point of the substrate. The thickness of sputtering deposited film is usually soλ~/μm
degree, preferably about 200 to 10θOλ.

The target material is T8 or Te as the base material.
Examples include metal alloys containing do, Pb, Bi, db, Sn, Ge, As, and the like.

In the present invention, the reactive gas to be mixed with Ar is a gas containing one or more organic or inorganic fluorides, such as tetrafluoromethane, tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, Fluoropylene hexafluoride: Fluorinated carbon gas such as vinyl fluoride and vinylidene fluoride, fluorinated hydrocarbon gas, and fluorinated chlorinated carbon gas: Fluorinated chalcogen gas such as selenium hexafluoride and sulfur hexafluoride, trifluoride A silicon fluoride gas such as a chemical compound, and a metal fluoride gas such as silicon tetrafluoride or germanium tetrafluoride are used.

one or more of the above reactive gases;
In the mixed gas with Ar gas, the proportion of the reactive gas is selected so that the resulting sputtered deposited film is amorphous and does not cause significant damage to the substrate. The range fi differs depending on the discharge conditions and the type of reactive gas, but generally the SO ratio (volume ratio)...jK is required.

The sputtering deposited film in the present invention was confirmed to be amorphous by X-ray and electron diffraction methods. While the deposited film obtained by sputtering with a gas consisting only of Ar is polycrystalline, the J1 peak in which the sputtered deposited film in the present invention becomes amorphous is not necessarily clear, but the reactive gas molecules in the present invention Since the film contains fluorine atoms, fluorine ions and fluorine radicals are generated in the glow discharge plasma, and etching occurs simultaneously with the deposition of the film on the substrate, which hinders the growth of the crystal layer and causes the formation of grains and grain boundaries. Therefore, if this is used as a recording medium, the recording sensitivity and bit shape can be made uniform, and furthermore, the reproduction noiser by the laser source can be used.
auiri can be achieved.

In the present invention, the composition of each element in the sputtering deposited film can be controlled by the composition of the alloy serving as the target material.
When using 9S, SS- or S can be mixed into the deposited film from the gas phase by decomposition of the reactive gas in the plasma. In this case, discharge conditions and A
By controlling the mixing ratio of r and reactive gas, the composition of the sputtered deposited film can be controlled widely and continuously, and the composition of each element in the depth direction of the deposit can be controlled over a wide range and continuously. It is also possible to give the desired distribution.

Furthermore, the above-mentioned light etching of the substrate surface by fluorine ions or fluorine radicals also has the effect of uniformizing the adhesion between the substrate and the sputtering deposited film.

In the recording medium according to the present invention, a sputtered deposited film of a metal compound is formed on the substrate as described above, and furthermore, recording sensitivity is improved and the substrate surface is modified in the bit shape between the substrate and the sputtered film. Undercoat layer for improvement etc.? A protective film can also be provided on the recording medium to protect the recording medium.

Hereinafter, an example of the manufacturing process of a recording medium according to the present invention will be described with reference to the drawings.

FIG. 1 is an example of an apparatus for manufacturing an optical recording medium according to the present invention. In the figure, (1) is a vacuum vessel, (2) is an electrode, (3) is an alloy target, (4) is a substrate, (5) is a gas inlet, (6) is a shutter, and (the sword is an exhaust port).

The above-mentioned improved optical recording medium is manufactured in a vacuum container (1
) is evacuated to the level of /0-' Torr, Ar gas is introduced from the inlet (5) so that the internal pressure of the container fi+ is 0 mTorr to several /OmTorr.

- Clean the get (3) surface. After that, the inside of the vacuum container was evacuated again to the 10-' TOrr range, and the scum mixed with Ar gas and the reactive gas of the present invention in a predetermined volume ratio was introduced through the inlet 15+, and the high Apply the Zhou force to wake up Iil'R1. after that.

The shutter (6) is opened for a certain period of time to form a sputtering deposited film on the 5th substrate (4). The deposition rate of the film can be changed mainly by changing the radio frequency power and the pressure inside the TC empty vessel (1).

(Example/) After evacuating empty container A to JXlo-' Torr,
Gas, 3% CF by volume, and cass km were introduced together,
Set the total pressure to 5x 70-” Torr 2. Substrate 11!l
! Between electrode and target fIll electrode /J, r&MHz
, j? 0WI) High frequency power was applied to generate glow discharge, and sputtering was performed. The target has an atomic ratio Tel! A sputtered film of 4tj nm was deposited on the substrate using an alloy with N%Sθ/j9. Next, when recording and restraining was performed on this optical recording medium using a GaAs semiconductor laser with a wavelength of I J Onm, the 0/N ratio (C
arrler to No.1se flatio)
5 odB was obtained.

(Example-) SF and gas were mixed with Ar gas at a volume ratio of 39% and introduced into a vacuum vessel, and the volume ratio was 41% as in Example/[S. ;nm sputter deposited film was deposited on the substrate. Using the obtained optical recording medium, recording and reproduction were performed with a laser in the same manner as in Example 1, and the results were as follows: C7IJ comparison. I got dB.

It was the sputtering structure of the above-mentioned Example/and Example 2. In particular, it was possible to prevent the reflectance from increasing immediately after the start of the accelerated DiJ test, which usually changes significantly.

(Comparative example) A 21 f j ! ×10′″” TO
rr'! / J * 5 ALiH2('
) A glow storm is generated between the substrate and the target at the frequency 't64 force joW.

The target is Kyokohi Tf3g! *, Sez, t% alloy was used to form 41oo^ 'II' 9 s@Tuishiryo on the substrate. The obtained optical recording medium was subjected to a recording start-up test using a half-body laser, and what was the O/N ratio? It was jdB.

(Effects of the Invention) According to the present invention, jL has excellent stability over time, good ratio (Carriert
o No.1se Ratio), a recording medium with further improved pit shape can be obtained2).

[Brief explanation of drawings]

FIG. 1 shows an example of an apparatus for manufacturing a target recording medium according to the present invention. In the figure / means vacuum capacity 2J1- is 1! Kirei, 3 is target%
DA indicates the board, S the gas inlet, O the shutter, and RI the exhaust port.

Claims (2)

[Claims] (1) A deposited film containing Te is formed on a substrate by reactive sputtering using a metal containing Te as a target material in a mixed gas of a reactive gas consisting of one or more organic or inorganic fluorides and Ar gas. An optical recording medium formed by forming an optical recording medium. (2) The proportion of reactive gas in the mixed gas is 1 to 50% by volume
The optical recording medium according to claim 1, characterized in that: