JP2651004B2 - Method for manufacturing optical information recording member - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for manufacturing an optical information recording member such as a disk for digital memory, and in particular, to an optical information recording member having high reliability and long life. The present invention relates to a production method suitable for obtaining

[Conventional technology]

Optical information recording members (hereinafter referred to as optical disks) include video disks, compact disks, digital memory disks, etc. Among them, digital memory disks have high reliability because they handle digital information. A long life is required. One measure of the high reliability and longevity of such optical discs is at 60 ° C and 95 ° C.
For example, even if the disk is left under the environment of% RH (relative humidity) for 1000 hours, the information is held in the disk.

FIG. 2 is a sectional view showing a partial section of a general digital memory disk. As shown in FIG. 2, the disk for digital memory usually has a transparent plastic resin substrate 1, a recording film 2 made of a chalcogenide compound or the like, a protective film 3 made of an ultraviolet curable resin, and an adhesive layer made of an adhesive or the like. 4.

Conventionally, a digital memory disk constructed as shown in FIG. 2 is placed in an environment of 60 ° C. and 95% RH as described above.
If left for about 100 hours and taken out in an environment at room temperature, blisters 5 as shown in FIG. 3 may be generated in the portion of the recording film 2, which makes it difficult to read or write information. there were.

The inventors of the present application have previously examined the blistering phenomenon and found that the cause is a decrease in the adhesive force between the substrate and the recording film due to moisture contained in the substrate, and prevent the blistering phenomenon. It was clarified that it was important to remove the moisture contained in the substrate and to suppress the release of moisture even during the formation of the recording film, and by irradiating the surface of the plastic resin substrate with plasma, A method for forming a recording film by suppressing the release of moisture from a substrate by sputter-forming the recording film in a relatively low vacuum of about 0.3 to 1 Pa while removing moisture contained therein was proposed. (Applied in Japanese Patent Application No. 62-22465).

Further, as a conventional technique relating to the production of an optical disk in which the substrate surface or the like is exposed to plasma, those described in JP-A-63-46636 and JP-A-62-298944 can be cited.

In the following description, plasma irradiation and
Exposure in plasma is collectively referred to as plasma processing.

[Problems to be solved by the invention]

However, in the above-mentioned prior art, sufficient consideration has not been given to contamination on the substrate surface during plasma processing, and it has been difficult in some cases to completely prevent the occurrence of the blistering phenomenon by the above-mentioned method.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems in the prior art and prevent the recording film from undergoing a blistering phenomenon (hereinafter referred to as a blistering defect) even when exposed to a high-temperature and high-humidity environment for a long time. An object of the present invention is to provide a method for manufacturing an optical disk.

[Means for solving the problem]

The above object is to change the plasma processing conditions during the plasma processing,
This is achieved by performing processing with low-energy plasma ions under conditions of low input power and high plasma gas pressure.

[Action]

As a source of contamination on the surface of the plastic resin substrate during the plasma processing, there is a recording film substance adhering to a substrate holder holding the substrate. As a material for these recording films, metals or chalcogenide compounds are generally used. Therefore, in order to prevent the above-described contamination of the surface of the plastic resin substrate during the plasma treatment, the etching rate of the plastic may be set to be higher than the etching rate of the contaminated material. For this purpose, processing may be performed with low-energy plasma ions, and the plasma processing may be performed under conditions of low input power and high plasma gas pressure. In addition, performing treatment with low-energy plasma ions also has the effect of reducing decomposition of the plastic substrate surface. By these effects, the adhesive force between the substrate and the recording film can be improved, and blistering defects can be prevented.

As the specific conditions of the low input power and the high plasma gas pressure, as described later, the plasma gas pressure is 0.
The input power is preferably 7 Pa or more and 200 W or less.

〔Example〕

Hereinafter, Examples of the present invention will be described in detail along with Comparative Examples.

Example 1 A polycarbonate substrate was used as a plastic substrate, and processing was performed in argon plasma.

FIG. 1 shows a schematic view of the apparatus used. In FIG. 1, reference numeral 11 denotes a polycarbonate substrate having a diameter of 130 mm and a thickness of 1.2 mm. After evacuating the vacuum chamber 13 attached to the substrate holder 12 to a pressure of 5 × 10 ⁻³ Pa, An argon gas was introduced from the gas inlet 14 and adjusted to a predetermined pressure by the flow control valve 15. Thereafter, the changeover switch 16 was switched to the A side, and a voltage was applied by the RF power supply 17 to generate plasma, and plasma processing was performed. Here, the frequency of 13.56 MHz is used as the RF frequency, but the frequency is not limited to this.

Next, the gas introduction valve (not shown) is closed, and the inside of the vacuum chamber 13 is evacuated to a pressure of 5 × 10 ⁻³ Pa.
Open the gas introduction valve again and supply argon gas with gas pressure of 0.
Introduced until the pressure became 7 Pa, switched the changeover switch 16 to the B side, and attached the target 18 of the recording film material
A voltage was applied to 19 to generate plasma, the shutter 20 was opened, and a recording film was formed on the polycarbonate substrate 11 by sputtering. As the recording film, an Sb-Se-Bi-based chalcogenide recording film was used, and the film thickness was 100 nm. In the sputtering, a magnetron sputtering method using the magnet 21 was employed. Thereafter, a protective film made of an ultraviolet curable resin and an adhesive layer made of an adhesive were formed to obtain an optical disk as shown in FIG.

The disk was left in an environment of 60 ° C. and 95% RH for 100 hours, then taken out in an environment of room temperature, and inspected for the number of blister defects. Table 1 shows the results.

When the input power at the time of the plasma processing is 100 W and the argon gas pressure is 1 Pa, if the processing time is lengthened, the blister defect is reduced and becomes zero after 3 minutes or more. Table 1 shows the etching depth of the substrate corresponding to the processing time. By etching the substrate surface by 20 nm or more by plasma processing, the low molecular layer on the substrate surface is removed and at the same time, the moisture on the substrate surface is reduced. As a result, the adhesive force between the polycarbonate substrate and the recording film is increased, and blistering defects can be prevented.

Comparative Example 1: As Comparative Example 1, the results of treatment with plasma ions having a higher energy than that of Example 1 are shown in Table 2.

The input power is 250W, the argon gas pressure is 0.3Pa,
Other than this, it is completely the same as the first embodiment. Reducing the argon gas pressure is equivalent to reducing the density of the argon gas, increasing the mean free path of argon ions,
Substantially increase the kinetic energy of argon ions. An increase in the input power corresponds to increasing the acceleration voltage of the argon ions, which also increases the kinetic energy of the argon ions. As shown in Table 2, when treated with high-energy argon ions, blistering defects can be reduced more than in the case of no treatment (treatment time of 0 minutes), but they cannot be completely eliminated. In addition, when the processing time is further lengthened and the substrate is etched deeply, the blister defect tends to increase. This is because, when treated with high-energy algo ions, the polycarbonate substrate is etched not only on the surface but also on the periphery, and the recording film substances and the like adhering to the periphery adhere to the surface of the polycarbonate substrate, so that the substrate surface is contaminated. As a result, blister defects occur. As a result of elemental analysis of the sample treated for 60 minutes shown in Table 2 by the ESCA method, elements of the recording film such as Sb and Se were detected, and it was found that the above-mentioned reattachment occurred.

Next, in order to examine under what plasma processing conditions the above-mentioned redeposition occurs, the etching rate of the polycarbonate and the etching rate of the recording film were measured.
The result is shown in FIG. The apparatus used was Example 1.
Are the same as those shown in FIG. As shown in FIG. 4, the etching rate of the recording film decreases as the argon gas pressure increases, while the etching rate of the polycarbonate substrate tends to increase. In order to show these relationships more quantitatively, the etching rate ratio (the etching rate of the recording film / the etching rate of the recording film / the
Take the etching rate of the polycarbonate substrate)
This is shown in FIG. 6 and FIG. FIG. 5 shows the relationship between the input power and the etching rate ratio using the argon gas pressure as a parameter, and FIG. 6 shows the relationship between the argon gas pressure and the etching rate ratio using the input power as a power meter. is there. From Fig. 5, the argon gas pressure is 0.3P
In the case of processing with argon ions of low energy and high energy, the etching rate ratio is greater than 1, that is, the rate of etching the recording film is higher than the rate of etching the polycarbonate substrate. The surface of the polycarbonate substrate is contaminated by the redeposition of the recording film material on the periphery of the substrate. The etching rate ratio decreases as the argon gas pressure increases and as the input power decreases. Therefore, it is understood that treatment with low-energy argon ions is a point for reducing the surface contamination of the polycarbonate substrate. 5 and 6, the plasma processing conditions for setting the etching rate ratio to 1 or less are such that the argon gas pressure is 0.6 Pa or more and the input power is 300 W or less. Further, the etching rate ratio is 0.6 or less, that is, the etching rate ratio of the substrate is 1.6 times or more of the etching rate of the recording film, more preferable plasma processing conditions, argon gas pressure is 0.7 Pa or more, input power is 200W or less. is there.

Example 2 In the same manner as in Example 1, Table 3 shows the inspection results of blistering defects when the argon gas pressure and the input power were changed as plasma processing conditions. In this embodiment, the substrate etching depth is fixed at 100 nm.

As shown in Table 3, under various plasma processing conditions, if the etching rate ratio is 0.8 or less, the number of blister defects can be 2 or less, but it is preferable that the etching rate ratio be 0.6 or less. Then, the blister defect could be reduced to zero.

Comparative Example 2: In the same manner as in Example 1, when plasma processing was performed under plasma processing conditions in which the etching rate ratio was 1 or more,
Table 4 shows the inspection results of blistering defects. In this embodiment, the argon gas pressure is fixed at 0.3 Pa, and the input power is 1
Changed from 00W to 300W. The processing time is changed so that the etching depth of the substrate becomes 100 nm.

As shown in Table 4, when the etching rate ratio is 1 or more, the blister defect cannot be prevented. In addition, when the etching rate ratio is constant at 1.25, even if the same amount is etched, the blistering defect increases as the processing time is longer. It reflects that it is easy to proceed.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, since the contamination of the substrate surface can be prevented when performing the plasma processing of a substrate, the optical disk excellent in reliability can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a plasma processing apparatus used in one embodiment of the present invention, FIG. 2 is a partial cross-sectional view showing a general digital memory disk, and FIG. 3 is a digital memory when a blister defect occurs. FIG. 4 is a characteristic diagram showing a relationship between an argon gas pressure and an etching rate in a plasma process, FIG. 5 is a characteristic diagram showing a relationship between an input power and an etching speed ratio in a plasma process, FIG. 6 is a characteristic diagram showing the relationship between the argon pressure and the etching rate ratio in the plasma processing. DESCRIPTION OF SYMBOLS 1 ... Plastic resin substrate, 2 ... Recording film, 3 ... Protective film, 4 ... Adhesive layer, 5 ... Bulging, 11 ... Polycarbonate substrate, 12 ... Substrate holder, 14 ... Gas inlet, 15 …… Flow control valve, 17 …… RF power supply, 19 …… Electrode.

Claims (1)

(57) [Claims] 1. A manufacturing method for manufacturing an optical information recording member in which an information recording film is formed after irradiating an argon plasma to a polycarbonate substrate, wherein the plasma irradiation is performed at a plasma gas pressure of 0.7 Pa or more and A method for producing an optical information recording member, wherein the method is performed under the condition that the input power is 200 W or less.