JP3085145B2 - Manufacturing method of optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical recording medium, and more particularly, to a method for producing an optical recording medium which absorbs light 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 disc (commonly called CD-
R disk) has been put to practical use. For forming the recording film, a method of dissolving a dye material in a solvent and applying the dye material on a substrate by a spin coater is generally adopted. At this time, the recording film is required to have a very small thickness of 0.1 to 0.3 μm and uniformity over the entire surface. In order to realize this, the type of the solvent and the precise control of the turntable are required. The development of coating know-how and the thorough management of coating atmosphere and substrate surface condition have been proposed.

[0003]

However, in the above-mentioned conventional method, as the thickness becomes smaller, for example, 0.1 μm
When approaching, conventional know-how and management methods limit the ability to absorb variations due to variations in film thickness between disks and partial thickness unevenness within the disks. That the outer circumference tends to be thicker than the inner circumference, which makes it extremely difficult to form a recording film uniformly and stably between disks or within a disk. Has problems.

[0004] The present invention solves the above-mentioned conventional problems, and improves the performance variation caused by uneven thickness between disks or within a disk, thereby improving the quality and the stability of the quality. An object of the present invention is to provide a method for manufacturing a recording medium.

[0005]

In order to achieve this object, a manufacturing method according to the present invention is a method of recording a dye by depositing a dye material on a substrate in a vacuum chamber having a plurality of vacuum chambers. In this method, a film is formed, and subsequently, a reflective film is formed in another chamber by vapor deposition or sputtering of a metal material.

[0006]

This method employs a vacuum evaporation method capable of controlling the formation of a thin film at the atomic and molecular levels, so that at the time of film formation, a dye recording film having excellent uniformity over the entire surface at a film thickness of submicron or less. Can be formed, and then a reflective film is continuously formed in another vacuum chamber to prevent non-uniformity due to recrystallization of the dye material after forming the dye recording film, and to form a uniform dye recording film. Fix it in the state.
These make it possible to form a uniform and stable dye recording film. In addition, heat treatment of the substrate surface in advance reduces the effect of outgassing, making it even more uniform, and performing discharge treatment further reduces surface energy and improves wettability. Thus, 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 five-room in-line type 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,
6e, 6f, and a loading door 7 and a take-out door 8 are attached to the front and rear. Each chamber is evacuated to a predetermined degree of vacuum by independently provided evacuation devices 9a, 9b, 9c, 9d, 9e. The substrate holder 10 on which a plurality of plastic substrates are mounted is sequentially transported through the chambers.

[0008] The trial production of a medium starts by mounting a predetermined number of polycarbonate substrates (hereinafter referred to as PC substrates) having a diameter of 120 mm on a substrate holder 10 and carrying the substrate holder 10 into the loading chamber 1 with the opening door 7 opened. Here, after being evacuated to a predetermined degree of vacuum, it is transported to the surface treatment chamber 2, where the outgassing process is performed by the heating lamp 11 and the surface modification process is performed by the discharge electrode 12. The outgas treatment is performed by heating the substrate surface with a far infrared heater for about 10 seconds to 100-1.
Adjust to 50 ° C and remove adsorbed water. In the surface modification treatment, oxygen or argon gas is introduced into the surface treatment chamber 2 and a high frequency voltage of 13.56 MHz and 500 to 1500 V is applied to the discharge electrode to generate plasma, and the substrate surface is exposed to the plasma for about 10 seconds. This is done by having

Subsequently, the dye material 13 is transferred to the dye film forming chamber 3, where a dye material 13 of azo type, phthalocyanine type, anthraquinone type or the like is deposited in a thickness of 0.1 to 0.3 μm. For the evaporation of the dye material, the dye material 13 is put into a crucible 14 and heated to 200 to 500 ° C. by a heater 15 to evaporate.

Here, the degree of vacuum when depositing the dye is 1
As a result of study from 0 ^-1 to 10 ^-7 torr, 10 ^-2 torr
When the vacuum degree is higher than r, an extremely low evaporation rate and partial decomposition of the dye material are observed, so that the vacuum degree is preferably lower than 10 ^-3 torr.

The angle of incidence of the vaporized dye vapor on the substrate (the angle formed by the perpendicular to the substrate and the direction in which the vapor enters) is also 6 degrees.
If the angle exceeds 5 degrees, the optical characteristics of the dye recording film, especially the reflectance, decrease. Therefore, it is preferable that the angle of inclination is 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 and adjusted in order to make the surface uniform. Further, it goes without saying that providing the substrate holder with the substrate revolving mechanism is effective in suppressing the variation width between substrates in the same batch. In order to ensure uniformity between lots, it is also important to install a crystal oscillation type or atomic absorption type monitor and control the film thickness.

Subsequently, the film is moved to the reflection film forming chamber 4, where the heat evaporation source 17 evaporates the reflection material 16 such as gold or aluminum 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, dye materials generally deteriorate in performance due to light,
In a film forming method using plasma, the performance tends to slightly decrease due to the light emission, and the vacuum deposition method is more preferable.

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

Thereafter, the substrate holder 10 is moved to the take-out chamber 5, the take-out door 8 is opened, and the substrate holder 10 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 structure of the optical recording medium manufactured as described above. The optical recording medium is a substrate 18, such as polycarbonate (PC) or polymethyl methacrylate resin (PMMA), a dye recording film 19, a reflection film 20, a protective film 2, and the like.
It has a laminated structure of 1. Here, the dye recording film is formed to have a thickness of 0.1 μm and the thickness variation is within ± 10%. When combined with the self-revolution mechanism, it can be formed with a variation within ± 5%. Furthermore, in terms of stability, there has been no change in the appearance even after one month from the beginning.

Heat treatment of the substrate surface with a lamp has the function of reducing and stabilizing outgassing from the substrate, and removes the adverse effect of the outgassing on the uniform adhesion of the dye film. In the case of surface treatment using plasma discharge, the adhesion strength between the substrate and the dye film is improved,
Even when the film thickness was increased, the effect that the peeling hardly occurred was obtained. It is also considered that recrystallization is further suppressed. As described above, the surface treatment suppresses the dependence on the substrate at the time of the treatment, and further ensures uniformity and stability.

On the other hand, for comparison, coating with a spin coater was also attempted, but the variation was 3 μm at a thickness of 0.1 μm.
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 for depositing a dye material in a vacuum chamber having a plurality of vacuum chambers and subsequently forming a reflective layer continuously in another vacuum chamber. As a result, uniformity of ± 10% or less was obtained over the entire surface of the lot, and a similar level of uniformity was obtained between lots. Accordingly, variations in electrical performance such as output changes and optimum power changes due to thickness unevenness can be suppressed, and the product yield has been significantly improved from 50% to 90%.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing an example of the structure of an optical recording medium according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preparation room 2 Surface treatment room 3 Dye film formation room 4 Reflection film formation room 5 Extraction room 6a-6f Gate valve 9a-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

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Yoshiyuki Takase 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-178934 (JP, A) JP-A-61- 198451 (JP, A) JP-A-1-229441 (JP, A) JP-A-3-20731 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B 7/26

Claims (4)

(57) [Claims] 1. The method is performed in a vacuum chamber having a plurality of vacuum chambers.
A method for manufacturing an optical recording medium, comprising: heating a substrate in a first vacuum chamber of the plurality of vacuum chambers.
After the treatment or discharge treatment, a dye material is deposited on the substrate in the second vacuum chamber to form a recording film.
Form, method of manufacturing an optical recording medium and forming a reflection film in the third vacuum chamber. 2. The method for manufacturing an optical recording medium according to claim 1, wherein the dye material is formed at a degree of vacuum 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 a vapor having a vapor entrance oblique angle of 65 degrees or less. 4. The method for manufacturing an optical recording medium according to claim 1, wherein the reflective film material is formed by a vacuum deposition method.