JPH02227842A - Production of optical information recording member - Google Patents

Abstract

PURPOSE:To prevent the generation of blistering of an information recording film even if the recording film is exposed to environment of a high temp. and high humidity over a long period of time by executing the irradiation of plasma under specific conditions in the case of forming the recording film after irradiating a plastic resin substrate with the plasma. CONSTITUTION:The prevention of the contamination on the surface of the plastic resin substrate 1 at the time of a plasma treatment is attained simply by executing the etching in such a manner that the etching rate of plastic is higher than the etching rate of a contaminating material. The treatment with the plasma ion of low energy is necessitated and the execution of the plasma treatment under the conditions of a low input power and high gaseous plasma pressure is necessitated for the above-mentioned purpose. The more specific conditions of the low input power and the high gaseous plasma pressure are >=0.7Pa gaseous pressure of plasma and <=200W input power. The adhesive strength of the substrate 1 and the recoding film 2 is improved in this way and the blistering 5 is prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing optical information recording members such as digital memory disks, and in particular, to an optical information recording member that has high reliability and long life. It relates to a manufacturing method suitable for obtaining.

[Conventional technology]

Optical information recording members (hereinafter referred to as optical discs) include
There are video discs, compact discs, digital memory discs, etc., and among them, digital memory discs are required to have high reliability and a long lifespan because they handle digital information.

One measure of the high reliability and long life of such optical discs is that even if the disc is left in an environment of 60°C and 95% RH (relative humidity) for 1000 hours, the information will not be retained on the disc. One example is the fact that

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

Conventionally, when a digital memory disk configured as shown in FIG. In some cases, a bulge 5 as shown in Part 3 may occur in the area, which makes it difficult to read or write information.

The inventors of the present application first investigated the above-mentioned blistering phenomenon and found that the cause of the blistering phenomenon was a decrease in the adhesion between the substrate and the recording film due to the moisture contained in the substrate, and the aim of the present invention is to prevent the blistering phenomenon. The moisture contained in the substrate is removed,
It was revealed that it is important to suppress the release of moisture even during the formation of a recording film, and the moisture contained in the substrate was removed by irradiating the surface of the plastic resin substrate with plasma, and furthermore, the moisture contained in the substrate was removed by irradiating the surface of the plastic resin substrate with plasma. We have proposed a manufacturing method in which the recording film is formed by sputtering in a relatively low vacuum of about 3 to 1 Pa, thereby suppressing the release of moisture from the substrate. (Special application 1986-224
Published in issue 65).

Furthermore, as a conventional technique for manufacturing optical disks in which the substrate surface etc. are exposed to plasma, there is
Examples include those described in Publication No. 6, JP-A-62-298944, and the like.

In the following description, irradiation with plasma and exposure to plasma will be collectively referred to as plasma treatment.

[Problem to be solved by the invention]

However, the above-mentioned conventional technology does not give sufficient consideration to contamination of the substrate surface during plasma processing.
With the above method, it may be difficult to completely prevent the occurrence of blistering.

The purpose of the present invention is to solve the problems in the prior art,
An object of the present invention is to provide a method for manufacturing an optical disc that does not cause blistering of a recording film (hereinafter referred to as a blistering defect) even when exposed to a high temperature and high humidity environment for a long time.

[Means to solve the problem]

The above object is achieved by setting the plasma processing conditions during plasma processing to be low input power and high plasma gas pressure, and performing processing with low energy plasma ions.

[Effect]

A source of plasma ion contamination on the surface of a plastic resin substrate is recording film material adhering to a substrate holder that holds the substrate. Metals or chalcogenide compounds are generally used as materials for these recording films.

Therefore, in order to prevent the above-mentioned contamination of the plastic resin substrate surface during plasma processing, it is sufficient to make the etching rate of the plastic higher than the etching rate of the above-mentioned contaminated material. The process may be performed using ions, and the plasma process may be performed under conditions of low input power and high plasma gas pressure. In addition, processing with low-energy plasma ions
It also has the effect of reducing decomposition of the plastic substrate surface. These effects can improve the adhesion between the substrate and the recording film and prevent blistering defects.

The specific conditions for the low input power and high plasma gas pressure are as follows: the plasma gas pressure is 0.
Preferably, the input power is 7 Pa or more and the input power is 200 W or less.

〔Example〕

Examples of the present invention will be described in detail below along with comparative examples thereof.

Example 1 A polycarbonate substrate was used as the plastic substrate,
Treatment was performed in argon plasma.

FIG. 1 shows a schematic diagram of the apparatus used. In Fig. 1, 11 is a polycarbonate substrate with a diameter of 130 m and a thickness of 1.2 mm, and the inside of a vacuum chamber 13 attached to a substrate holder 12 was evacuated to a pressure of 5 × 1 O-3 Pa. After that, inject argon gas into the gas inlet port 14.
Introduced from the flow rate! l! The pressure was adjusted to a predetermined value using the one-section valve 15. Thereafter, the changeover switch 16 was switched to the A side, voltage was applied by the RF power source 17 to generate plasma, and plasma processing was performed. Here, a frequency of 13.56 MHz was used as the RF frequency, but the frequency is not limited to this.

Then close the gas inlet valve (not shown).

After evacuating the inside of the vacuum chamber 13 to a pressure of 5 x 10-3 Pa, open the gas introduction valve again, introduce argon gas until the gas pressure reaches 0.7 Pa, and switch the changeover switch 16 to the B side to remove the recording film material. A voltage was applied to the electrode 19 to which the target 18 was attached 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, a 5b-3s-Bi chalcogenide recording film was used, and the film thickness was 1100 nm. Further, in the sputtering formation, a magnetron sputtering method was used using the magnet 21. Thereafter, a protective film made of an ultraviolet curing resin and an adhesive layer made of an adhesive were formed to obtain an optical disc as shown in FIG. 2.

After the disk was left in an environment of 60° C. and 95% RH for 100 hours, it was taken out to a room temperature environment and the number of blistering defects was inspected. The results are shown in Table 1.

The following is a margin table 1. When the input power during plasma processing is 100 W and the argon gas pressure is 1 Pa, the number of blistering defects decreases as the processing time increases 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 treatment, the low molecular layer on the substrate surface is removed and at the same time moisture on the substrate surface is also removed. This increases the adhesion between the polycarbonate substrate and the recording film, and prevents blistering defects.

Comparative Example 1: As Comparative Example 1, Table 2 shows the results of processing with plasma ions of higher energy than in Example 1.

Table 2 Input power: 250W, argon gas pressure: 0.3Pa
Everything else is the same as in Example 1. Lowering the argon gas pressure corresponds to lowering the density of argon gas, lengthens the mean free path of argon ions, and substantially increases the kinetic energy of argon ions. Furthermore, increasing 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, the blistering defects can be reduced more than when untreated (treatment time: 0 minutes), but cannot be completely eliminated.

Moreover, when the processing time is further increased and the substrate is etched deeply, the number of blistering defects tends to increase.This is because when treated with high-energy albo ions, polycarbonate substrates are etched not only on the surface but also on the surrounding area. , the surface of the polycarbonate substrate becomes contaminated due to recording film substances that were attached to the surroundings adhering to the surface of the polycarbonate substrate.
As a result, blistering defects occur. As a result of elemental analysis of the samples treated for 60 minutes shown in Table 2 using the ESCA method, recording film elements such as Sb and Ss were detected.
It was found that the above-mentioned re-deposition occurred.In order to investigate under what plasma processing conditions the above-mentioned re-deposition occurs, we compared the etching speed of polycarbonate and the etching speed of the recording film. It was measured.

The results are shown in FIG. 4, and the device used was Example 1.
This is the same as that shown in FIG. 1 used in . As shown in FIG. 4, the etching rate of the recording film decreases as the argon gas pressure increases, but on the contrary, the etching rate of the polycarbonate substrate tends to increase. In order to show these relationships more quantitatively, we use the etching speed ratio (recording film etching speed/
Etching speed of polycarbonate substrate) is taken, and the fifth
6 and 6.

Figure 5 shows the relationship between input power and etching speed ratio using argon gas pressure as a parameter, and Figure 6 shows the relationship between argon gas pressure and etching speed ratio using input power as a parameter. be. From FIG. 5, when the argon gas pressure is as low as 0.3 Pa and the etching is performed with high-energy argon ions, the etching speed ratio is greater than 1, that is, the recording film is etched faster than the polycarbonate substrate is etched. Since the speed is higher, the recording film material that was in the peripheral area of the polycarbonate substrate re-adheres to the surface of the polycarbonate substrate during plasma processing, thereby contaminating the surface. and,
The etching speed ratio becomes smaller as the argon gas pressure becomes higher and the input power becomes lower. Therefore, it can be seen that treatment with low-energy argon ions is the key to reducing surface contamination of the polycarbonate substrate. From FIGS. 5 and 6, it is clear that the plasma processing conditions for making the etching rate ratio 1 or less are argon gas pressure of 0.
．． The input power is 6 Pa or more and the input power is 300 W or less. Further, more preferable plasma processing conditions in which the etching speed ratio is 0.6 or less, that is, the etching speed ratio of the substrate is 1.6 times or more than the etching speed of the recording film, are such that the argon gas pressure is 0.7 Pa or more, and the input Power is 200W or less.

Example 2: Table 3 shows the inspection results for bulging defects in the same manner as in Example 1, changing the argon gas pressure and input power as plasma processing conditions. In this example, substrate etching was performed. The depth is set to 10100n.

Table 3 As shown in Table 3, even under various plasma processing conditions, if the etching rate ratio is set to 0.8 or less, the number of blistering defects can be reduced to 2 or less; It is preferable to set the value to .6 or less, so that the number of blistering defects can be reduced to zero.

In the above embodiments, argon gas was used as the plasma processing gas, but the present invention is not limited to this, and the same effect can be achieved even if nitrogen gas, air, oxygen gas, or a mixture thereof is used. It goes without saying that this effect can be obtained.

Comparative Example 2: Table 4 shows the inspection results for blistering defects when plasma processing was performed in the same manner as in Example 1 under plasma processing conditions with an etching rate ratio of 1 or more. The gas pressure was kept constant at 0.3 Pa, and the input power was varied from 100 W to 300 W. Furthermore, the processing time was varied so that the etching depth of the substrate was 1100 nm.

As shown in Table 4 in Table 4 below, if the etching speed ratio is set to 1 or more, blistering defects cannot be prevented.When the etching speed ratio is constant at 1.25, the same amount is etched. Even though the longer the processing time, the more blistering defects there are.

This reflects the fact that the longer the processing time, the more contamination of the substrate surface progresses.

In each of the Examples and Comparative Examples described above, the substrate is a polycarbonate substrate, but the plasma processing method according to the present invention can be applied to other disk substrates such as PMMA, glass, etc., and has great effects. Needless to say, you can get it.

〔Effect of the invention〕

According to the present invention, since contamination of the substrate surface can be prevented when performing plasma processing on the substrate, it is possible to provide an optical disc with excellent reliability.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a plasma processing apparatus used in an embodiment of the present invention, Fig. 2 is a partial sectional view showing a general digital memory disk, and Fig. 3 is a digital memory when a bulge defect occurs. FIG. 4 is a characteristic diagram showing the relationship between argon gas pressure and etching rate in plasma processing, FIG. 5 is a characteristic diagram showing the relationship between input power and etching rate ratio in plasma processing, FIG. 6 is a characteristic diagram showing the relationship between argon pressure and etching rate ratio in plasma processing. DESCRIPTION OF SYMBOLS 1... Plastic resin substrate, 2... Recording film, 3... Protective film, 4...
Adhesive layer, 5...Bulge. 11... Polycarbonate substrate. 12...Substrate holder, 14...Gas inlet,
15...Flow control valve, 17...RF constant power source 19...Electrode. For the purpose of illustration, patent attorney Katsuo Ogawa β, a. 19 Denki Memories 20 Contains Wa 21 Kureishi Tsushima Figure 15゛5.3-Kureshima + Figure Argon Glass Detour- (7% 3

Claims (1)

[Claims] 1. In a manufacturing method for manufacturing an optical information recording member in which an information recording film is formed after irradiating a plastic resin substrate with plasma, the plasma irradiation is performed at a plasma gas pressure of 0.7 Pa or more and an input power of 1. A method for manufacturing an optical information recording member, characterized in that the manufacturing method is carried out under conditions of 200 W or less.