JPH097237A - Production of optical recording medium - Google Patents

Abstract

PURPOSE: To obtain a production method of an optical recording medium by which variation in the performance of write-once optical disks (CD-R) due to irregular thickness can be improved and the quality and stability of quality can be improved. CONSTITUTION: A dye recording film 19 is formed by vacuum vapor deposition method in one chamber of a vacuum tank having plural vacuum chambers, and successively, a reflecting film is continuously formed in another vacuum chamber to obtain a stable dye recording film 19 having uniform film thickness. Before the dye recording film 19 is formed, the surface of the substrate 18 is subjected to heat treatment or discharge treatment to suppress dependence on the substrate 18 and to ensure uniformity and stability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to a method of manufacturing an optical recording medium which has absorption in a wavelength region of 400 to 800 nm and which is written and read by a semiconductor laser.

[0002]

2. Description of the Related Art A write-once type optical disk (commonly called CD
R disk) has been put to practical use. For the formation of this recording film, a method of dissolving a dye material in a solvent and applying the dye material on a substrate with a spin coater is generally adopted. At this time, the recording film is required to have a very thin thickness of 0.1 to 0.3 μm and be uniform over the entire surface. In order to achieve this, the kind of solvent and precise control of the turntable are required. Countermeasures such as development of coating know-how and thorough management of coating atmosphere and substrate surface condition have been proposed.

[0003]

However, in the above conventional method, the thinner the thickness is, for example, 0.1 μm.
If it becomes closer, there is a limit to absorbing the variation due to the film thickness variation between disks and the partial thickness variation within the disk by the conventional know-how and management method. Furthermore, the essential issue of this method is the radial problem. The fact that there is an inclination in the direction, that is, the outer periphery tends to be thicker than the inner periphery, and it is extremely difficult to form a recording film uniformly between discs or within a disc due to these factors. I have a problem.

The present invention solves the above-mentioned problems of the prior art, and it is possible to improve performance variation caused by uneven thickness between discs or within discs, and to improve quality and stability of light. It is an object to provide a method for manufacturing a recording medium.

[0005]

In order to achieve this object, the manufacturing method of the present invention comprises a vacuum chamber having a plurality of vacuum chambers in which a dye material is vapor-deposited on a substrate to record a dye. A film is formed, and subsequently, a reflection film is formed by vapor deposition or sputtering of a metal material in another chamber.

[0006]

In this method, by adopting the vacuum deposition method capable of controlling the thin film formation at the atomic and molecular level, at the time of film formation, a dye recording film excellent in uniformity over the entire surface in a film thickness of submicron or less. By continuously forming a reflective film in another vacuum chamber, it is possible to prevent non-uniformity due to recrystallization of the dye material after the dye recording film is formed, and to form a uniform dye recording film. Fix it as it is.
With these, a uniform and stable dye recording film can be formed. In addition, by heating the surface of the substrate in advance, the effect of outgas can be reduced, making it even more uniform, and by further performing discharge processing, the surface energy decreases and wettability is improved. As a result, recrystallization is further suppressed.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a film forming apparatus for manufacturing a recording medium by performing a film forming process on a plastic substrate. The film forming apparatus is a so-called in-line type having a five-chamber structure including a charging chamber 1, a surface treatment chamber 2, a dye film forming chamber 3, a reflective film forming chamber 4, and a take-out chamber 5. Gate valves 6a, 6b, 6c, 6d, and
6e and 6f, and a front door 7 and a front door 8 are attached to the front and rear. Each chamber is evacuated to a predetermined vacuum degree by vacuum evacuation devices 9a, 9b, 9c, 9d, 9e provided independently. A substrate holder 10 having a plurality of plastic substrates mounted thereon sequentially conveys each chamber.

The trial manufacture of a medium starts by mounting a predetermined number of φ120 mm polycarbonate substrates (hereinafter referred to as PC substrates) on the substrate holder 10 and loading the substrate holder 10 into the preparation chamber 1 by opening the loading door 7. Here, after being evacuated to a predetermined degree of vacuum, it is conveyed to the surface treatment chamber 2, where the heating lamp 11 performs outgas treatment and the discharge electrode 12 performs surface modification treatment. Outgas treatment is performed by heating the substrate surface with a far infrared heater for about 10 seconds to 100 to 1
The adsorbed water is removed at 50 ° C. In the surface modification treatment, oxygen or argon gas is introduced into the surface treatment chamber 2, a high frequency voltage of 500 to 1500 V at 13.56 MHz is applied to the discharge electrode to generate plasma, and the substrate surface is exposed to the plasma for about 10 seconds. It is done by

Then, the dye material is transferred to the dye film forming chamber 3, where an azo-based, phthalocyanine-based, anthraquinone-based dye material 13 is vapor-deposited to a film thickness of 0.1 to 0.3 μm. For the evaporation of the dye material, the dye material 13 is put in the crucible 14 and heated by the heater 15 to 200 to 500 ° C. to be evaporated.

Here, the degree of vacuum when depositing the dye is 1
As a result of studying from 0 ^-1 to 10 ^-7 torr, 10 ^-2 torr
At a bad vacuum degree of r or higher, an extreme decrease in evaporation rate and partial decomposition of the dye material were observed, so it is preferable to carry out at a vacuum degree of 10 ^-3 torr or less.

Further, the angle of inclination of the vaporized dye vapor into the substrate (the angle formed by the vertical line standing on the substrate and the direction of the vapor inclination) is 6
If it exceeds 5 degrees, the optical characteristics of the dye recording film, particularly the reflectance will be deteriorated. Therefore, it is preferable to perform it at an angle of incidence of 65 degrees or less.

Needless to say, in vacuum deposition, the shape of the evaporation source and the positional relationship between the substrate holder and the evaporation source must be optimized for uniformization within the surface. Further, it goes without saying that providing the substrate holder with the substrate auto-revolution mechanism is effective in suppressing the variation width between the substrates in the same batch. Further, in order to secure the uniformity between lots, it is important to install a crystal oscillation type monitor or an atomic absorption type monitor to control the film thickness.

Subsequently, the film is moved to the reflection film forming chamber 4, where the reflection material 16 such as gold or aluminum is evaporated by the heating evaporation source 17 to form a reflection film of 0.05 to 0.1 μm. At this time, other film forming methods such as sputtering, ion plating, and plasma CVD (Chemical Vapor Depositi
A method using a vacuum such as on) may be used. However, since dye materials generally cause performance degradation due to light,
In the film forming method using plasma, the performance tends to deteriorate due to the light emission, but the vacuum evaporation method is preferable.

At this time, if the dye film is formed by vapor deposition, the vacuum is broken, and the dye material is left to stand in the atmosphere for several days, the dye material is crystallized with the number of days left, and it may grow into fine crystals that can be observed with the naked eye. It's been found. It was also found that once the microcrystals were formed, the microcrystals could not be removed even if the reflective film was formed later. Therefore, in order to prevent this microcrystallization, it is required to continuously form the reflective film in the same vacuum chamber after forming the dye film.

After that, the substrate holder 10 is moved to the take-out chamber 5, the take-out door 8 is opened, and is sent to the next step, that is, the protective film forming step, to complete the disk.

FIG. 2 is a sectional view showing the construction of the optical recording medium manufactured as described above. The optical recording medium is a substrate 18 such as polycarbonate (PC) or polymethylmethacrylate resin (PMMA), a dye recording film 19, a reflective film 20, a protective film 2.
It has a laminated structure of 1. Here, the dye recording film has a film thickness of 0.1 μm and the film thickness variation is formed within ± 10%. When combined with a self-revolving mechanism, it can be formed with variations within ± 5%. Furthermore, in terms of stability, no change in appearance was observed not only in the initial stage but also after one month.

The heat treatment of the substrate surface by the lamp has a function of reducing and stabilizing the outgas from the substrate, and the adverse effect of the outgas on the uniform adhesion of the dye film is eliminated. In addition, when the surface treatment using plasma discharge is performed, the adhesion strength between the substrate and the dye film is improved,
Even if the film thickness is increased, the effect that peeling does not easily occur was obtained. Further, it is considered that the tendency is to further suppress recrystallization. In this way, the surface treatment suppresses the dependency on the substrate at the time of treatment and further ensures the uniformity and stability.

On the other hand, for comparison, coating with a spin coater was also tried, but the variation was 3 at a thickness of 0.1 μm.
It was 0 to 50% and 20 to 30% at 0.2 μm.

[0019]

As described above, according to the present invention, there is provided a method in which a dye material is vapor-deposited in a vacuum chamber having a vacuum chamber composed of a plurality of vacuum chambers and subsequently a reflective layer is continuously formed in another vacuum chamber. As a result, uniformity of ± 10% or less was obtained over the entire surface of each lot, and a similar level of uniformity was obtained between lots. Therefore, variations in electrical performance such as output changes and optimum power changes due to uneven thickness can be suppressed, and the product yield can be significantly improved from 50% to 90%.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a film forming apparatus for manufacturing an optical recording medium in an embodiment of the present invention.

FIG. 2 is a sectional view showing a structural example of an optical recording medium in an example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preparation chamber 2 Surface treatment chamber 3 Dye film formation chamber 4 Reflective film formation chamber 5 Extraction chamber 6a to 6f Gate valve 9a to 9e Vacuum exhaust device 10 Substrate holder 11 Heating lamp 12 Discharge electrode 13 Dye material 16 Reflective material 18 Substrate 19 Dye recording film 20 Reflective film 21 Protective film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiyuki Takase 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A vacuum chamber having a plurality of vacuum chambers, wherein a dye material is vapor-deposited on a substrate in one chamber to form a recording film,
Subsequently, a method of manufacturing an optical recording medium, characterized in that a reflective film is formed in another chamber. 2. The method for producing an optical recording medium according to claim 1, wherein the dye material is formed at a vacuum degree of 10 ⁻³ torr or less. 3. The method for producing an optical recording medium according to claim 1, wherein the dye material is formed with vapor having an oblique angle of entering vapor of 65 degrees or less. 4. The method for producing an optical recording medium according to claim 1, wherein the dye material is formed after the substrate surface is heat-treated. 5. The method for producing an optical recording medium according to claim 1, wherein the dye material is formed after the surface of the substrate is subjected to electric discharge treatment. 6. The method of manufacturing an optical recording medium according to claim 1, wherein the reflective film material is formed by a vacuum vapor deposition method.