JPH01220151A - Production of information recording medium - Google Patents

Abstract

PURPOSE:To improve the environmental resistance of the recording medium and to prolong the life thereof by executing reactive sputtering of a Te target in an atmosphere essentially consisting of gaseous N2, thereby forming a protective film on a recording film. CONSTITUTION:A gaseous mixture composed of gaseous hydrocarbon and gaseous argon is introduced into a vacuum vessel 1 and a voltage is impressed between the AgTe eutectic alloy target 4 and a counter electrode 7 to deposit and form the recording film 61 on a substrate 6 by the reactive sputtering. The gaseous hydrocarbon and the gaseous argon are then discharged and gaseous nitrogen and gaseous argon are introduced in place thereof into the vacuum vessel, then the sputtering is executed to form a protective layer 62 consisting of the TN time. The environmental resistance is thereby improved and the life is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a method of manufacturing an information recording medium in which information is recorded and reproduced using a laser beam.

(Prior art) To optically record and reproduce information using a laser beam, a recording film formed on a substrate is irradiated with a pulse modulated laser beam that corresponds to the information to be recorded. Information recording media are known in which holes, called pits, are formed by locally heating the media.

This type of information recording medium: ■ has an extremely high recording density and can be made large in capacity, ■ records and reproduces information without contact, so there is no wear on the recording medium, and ■ allows high-speed access. It has advantages such as , and is applied to so-called optical disks and optical cards. In addition, since the information recording medium has grooves (groups) for guiding the optical head on the substrate to enable access to information, a transparent resin material with excellent optical properties and good group formability is suitable as the substrate material. ing.

Information recording media are classified into various types depending on the material of the recording film. A user-recordable type of medium has a recording film whose optical properties change when irradiated with a light beam formed on a transparent substrate.The reproduction method is to irradiate the recording film with a laser beam, and then use the light to reflect the light. It is common to read recorded information by detecting light.

As the material of the recording film, chalcogen compounds, organic dyes, rare earth-transition metals, etc. are used. Recording films that take advantage of these optical changes have been formed on transparent resin substrates and have been put into practical use, but there have been very few materials that have a sufficient lifespan for single-layer recording films.

Therefore, S! 02°Aβ203. AβN,
A protective film made of an inorganic dielectric material such as ZnS was formed. However, there are still accelerated deterioration characteristics such as environmental tests,
Due to the history of high temperature and high humidity, deterioration of recording film quality and deterioration of recording and reproduction characteristics have appeared, and improvements in these problems have been desired.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for manufacturing an information recording medium that has a long life, excellent environmental resistance, high sensitivity, and high reliability.

[Structure of the Invention] (Means for Solving the Problems) In a method for manufacturing an information recording medium having a recording film that records and reproduces information by irradiation with a laser beam, N2 gas is applied onto the formed recording film. It is characterized in that the protective film is deposited by reactive sputtering using a Te target in an atmosphere containing Te as the main component.

(Function) The method for manufacturing an information recording medium according to the present invention uses the above-described means to produce Te in an atmosphere containing N2 gas as a main component.
Since the recording film is formed by reactive sputtering with a target, it is possible to obtain an information recording medium with long life and excellent environmental resistance while maintaining good recording sensitivity by forming a protective film (TN film). .

(Example) Hereinafter, an example of the method for manufacturing an information recording medium according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a sputtering apparatus for carrying out the present invention. That is, the vacuum container (2) is provided with a gas inlet (2) through which a mixed gas or the like is supplied, and an exhaust port (2) connected to a vacuum pump (not shown). A pair of metal targets and electrodes are provided inside the container (2), and each is connected to a direct current (DC) power source (not shown) via a terminal (2).

Further, a counter electrode (2) on which the substrate 0 is placed is provided at a position opposite to the electrode (B) in the container (G).

Substrate 0 is 130#φ, thickness 1.2. It is made of a transparent resin material such as polycarbonate, polymethyl methacrylate, or epoxy, and the surface of the substrate has a
Recording/reproducing guide grooves (groups) are formed in advance to a depth of approximately one Angstrom.

The recording film formation procedure is as follows: First, the inside of the vacuum container (G) is evacuated to about 2 x 1O-6 TOrr through the exhaust port (), and then hydrocarbon (CH4) gas and A
A mixed gas with r gas is introduced. The mixed volumes of CH4 gas and Ar gas are each 103CC)i, and the volume ratio is, for example, 1:1. Therefore, the gas pressure inside the container was
x 10-3 Torr, a DC power of, for example, 0.15 A is supplied between the target (c) and the counter electrode (2) to perform reactive sputtering. As a result, a recording film is deposited on the substrate (6) to produce an information recording medium.

Incidentally, the substrate θ was rotated at a speed of 18 rpm in order to make the deposited film uniform.

Next, stop the supply of C1-(4 and Ar gas to the sputtering gas inlet (2), and instead supply a mixed gas of N2 and Ar from the inlet (2).The sputtering pressure is set to 5 x 1.
While maintaining O-3 Torr and rotating the substrate 0 by 18 ppm, a power of 0.3 A is applied from the power supply, and as shown in FIG. 2, a TN film protective layer (62) is formed on the recording film (61).
was formed.

[Example-1] Te is used for the metal target (a). To deposit a recording film on the substrate 0, a total amount of 203CC1 (mixed gas of CH4 gas and Ar gas with a volume ratio of 1:1) is introduced.As a result of sputtering in this way, A recording film with a thickness of 50 nm could be obtained in seconds. During this time, the sputtering pressure in the container was maintained at 5 x 1O-3 TOrr.

Further, the appropriate thickness of the recording film is about 10 to 1100 nm.

Next, the supply of CH4 and Ar gas from the sputtering gas inlet (2) is stopped, and instead, a mixed gas of N2-10% and Ar is supplied from the inlet (2). Sputtering pressure 5
x 10-3 Torr and substrate θ to 18 ppm
While rotating, apply 0.3A of power from the power supply,
After about 1 minute, a TN film protective layer (62) with a thickness of about 10 nm was formed. The thickness of the protective layer is suitably about 5 to 50 nm, preferably 7 to 14 nm.

The information recording medium thus obtained was 80'C-85%R.
An environmental test was conducted using an accelerated deterioration test in a high-temperature, high-humidity tank. After that, we investigated the state of the light transmittance (T/To) using a laser beam with a wavelength (λ) of 830 nm. In comparison with (2), it can be seen that a good recording medium was obtained with no change even after 4000 hours. Note that the characteristic curve shown in FIG. 3(C) shows the case of a single Te layer without forming a protective film.

Furthermore, the relationship between the recording threshold power of the medium and the carrier noise ratio of the reproduction output after 2000 hours in an environmental test at 80'C and 85% RH was evaluated. As a result, the fourth
As shown in the figure, better results were obtained as shown in the characteristic curve (D) compared to Conventional Example 0 without the TN film protective layer. Also,
Only the TN film protective layer (62) according to the method of this invention was formed in 1100 nm on a 3i non-reflection plate, and 80'C-85% Rl-1
Figure 5 shows the X-ray diffraction results after 2000 hours in a high-temperature, high-humidity chamber. The figure shows the diffraction angle (2θ) on the horizontal axis and the X-ray radiation intensity on the vertical axis. This indicates that the state has changed to a crystalline state of 0, which includes 0, indicating that the durability as a recording medium has increased.

[Example-2] Under the same process as Example-1, In target was converted to C
A recording film (JD) was deposited to a thickness of 50 nm by reactive sputtering in a mixed gas of H4, Ar and 02. Thereafter, a TN film was formed by reactive sputtering using a Te target in a mixed gas of N2 and Ar. A protective layer was deposited.

As a result of evaluating the accelerated deterioration characteristics and CNR characteristics of the formed recording medium, the same characteristics as those of Example-1 shown in FIGS. 3 and 4 were obtained, respectively.

[Effect of the invention] As explained above, according to the manufacturing method of the present invention, TN
Due to the formation of a protective film layer, it has excellent environmental resistance and has a long lifespan.
An information recording medium with excellent reproduction characteristics can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the structure of a reactive sputtering apparatus used for manufacturing an information recording medium according to the present invention, FIG. 2 is a schematic cross-sectional view of an information recording medium manufactured by the manufacturing method according to the present invention, and FIG. Figures 5 through 5 are diagrams showing the characteristics of the information recording medium manufactured by the manufacturing method according to the present invention, including a light transmittance characteristic diagram (Figure 3) in an environmental resistance test and a carrier noise versus recording threshold power. They are a ratio characteristic diagram (Figure 4) and an X-ray diffraction characteristic diagram (Figure 5). ■...Vacuum container (2)...Gas inlet 0)...Metal target and electrode■...Substrate

Claims (1)

[Claims] In a method for manufacturing an information recording medium having a recording film that records and reproduces information by irradiation with a laser beam, reactive sputtering of a Te target in an atmosphere containing N_2 gas as a main component is performed on the formed recording film. A method for manufacturing an information recording medium, characterized in that a protective film is deposited and formed by.