JPS593730A - Method for forming recording film on base surface of information recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording film which has superior moisture resistance and is hard to deteriorate by treating a transparent plastic base surface where a recording film is formed in a gaseous plasma atmosphere under reduced pressure, and thus forming the recording film. CONSTITUTION:The transparent plastic base 14 which has grooves 3 for tracking pits 4 for information, etc., is placed in the gaseous plasma treating device consisting of a high-frequency generating coil 7, glass cylinder 8, gas supply pipe 9, vacuum pump 11, etc., and treated in the gaseous plasma atmosphere under reduced pressure. Vacuum deposition on the treated base is carried out to obtain a single-sided disk 1. Disks 1 are adhered together with a spacer member 2 between to obtain an information recording medium having a closed annular hollow part 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information recording medium that performs recording and reproduction using focused light.

As shown in FIG. 1, a disc-shaped information recording medium that performs recording and reproduction using a focused beam of light consists of a donut-shaped transparent plastic substrate 1 and an annular spacing member 2 in which tracking grooves 6 and information holes 4 are formed. It has a structure in which a hollow portion 5 is provided with the provided surfaces facing each other at a constant interval, and a recording film 6 is further provided on the opposing surface of the transparent plastic substrate. A known method is to form grooves and holes on the surface of these transparent plastic substrates directly on the substrate surface by injection molding or compression molding using a stamper, and then form a recording film on the substrate surface of the molded product by vapor deposition or the like. .

The transparent plastic substrate is mainly made of polymethyl methacrylate or polycarbonate. Polymethyl methacrylate has high transparency and low birefringence after molding, while polycarbonate has a lower birefringence than polymethyl methacrylate but has lower moisture absorption, making it suitable as a substrate for information recording media. This is because the recording film is made of Te.
, Se and As, 'I'i, Pb
.

It is one or a mixture of two or more of In, Cd, etc.

However, the recording film formed on the surface of the plastic substrate has the property that cracks become rough due to the action of water.

If an information recording medium is left in a humid atmosphere for a long time,
Since the humidity in the hollow portion becomes the same as the humidity in the atmosphere in which the recording film is left, there is a problem in that the recording film is affected by water, cracks occur, and the function as an information recording medium is lost.

An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a method for forming a recording film that is less susceptible to deterioration.

The gist of the present invention is to process the surface of a transparent plastic substrate on which a recording film is to be formed in a gas plasma atmosphere under reduced pressure to form a recording film on the surface.

By processing in a gas plasma atmosphere, the surface of the transparent plastic becomes chemically active and the adhesion between the plastic substrate and the recording film becomes strong. This is thought to be because no friction occurs.

Specifically, as the conditions for generating gas plasma, one type of gas, such as oxygen, argon, nitrogen, or a mixture of two or more types, is used as the gas. Among these, when oxygen is used, the surface activation effect is excellent.

The above object can be achieved by setting the gas pressure to 0.1 to 0.4 Torr, plasma output of 200 W, and treatment time of 0.5 to 3 minutes.

The pressure of the gas is 0. ITorr or less or processing time is 0
If the time is less than 5 minutes, the surface activation effect will not be sufficient and the time will be 0.
The plastic on the surface is removed by the plasma at 4 Torr or more or for 3 minutes or more, and the shapes of the tracking grooves and information holes formed on the surface are deformed, causing problems in recording and reproducing.

The experimental method related to the present invention will be described below.

As shown in FIG. 2, the gas plasma processing apparatus includes a glass cylinder 8 inside a high-frequency generating coil 7, and a gas supply pipe 9 disposed inside the cylinder 8. Holes 10 are provided so that the gas can be uniformly ejected into the cylinder 8.

One end of this cylinder 8 is connected to a vacuum pump 11.

The base body 13 is taken in and taken out by opening and closing the airtight door 12 attached to the other end. Place the base 16 in the center of the cylinder 8)
After operating the vacuum pump and supplying an appropriate amount of gas to adjust the partial pressure to an appropriate level, the high-frequency coil is energized to generate gas plasma within the cylinder and process the sample surface.

In addition, the concept of being in a gas plasma atmosphere described in the present invention also includes snot ringing, ion etching, etc.

Next, the present invention will be explained in detail with reference to examples.

Example 1 A positive type photoresist (AZ1350J) with a thickness corresponding to 1/4 wavelength of the readout light traveling in a medium with a refractive index n was coated with a spinner on a glass plate with a diameter of 355M and a thickness of 10m. 180 Orp around the center of this disk.
The film was rotated at a speed of m, irradiated with condensed argon laser light (wavelength: 4547 k), developed, and baked to form holes with a depth of 1/4 wavelength and grooves with a depth of 1/'8 wavelength. The power of the laser beam to be irradiated is reduced to 1/4 after baking at 120℃ for 1 hour.
The trap was adjusted so that a depth of +'/'8 wavelengths was formed. Next, a nickel film was formed on the surface by nickel mirror reaction.

On top of this nickel film, a current density of 1
Nickel plating was performed at 0 A/cJ, the plating layer was peeled off, and the photoresist transferred to the plating layer was dissolved and removed with acetone to obtain a stamp.

Next, the above-mentioned stand bar was attached to the inside of an injection mold, and a molding material containing polymethyl methacrylate as a main component and a mold release agent added thereto was used.

Molded at an injection pressure of 450 Kf/d and a cylinder temperature of 250°C, punched out a center hole, outer diameter 300mm, inner diameter 70m5. Thickness 1
．． A 2M transparent substrate was obtained.

The substrates formed as described above were placed in a gas plasma processing apparatus, and the surfaces of the substrates were treated under the conditions shown in Table 1 to obtain Examples 1 to 3 and Comparative Examples 1 to 3.

table 1. Plasma output 200W.

2. Comparative Example 1 was not subjected to gas plasma treatment.

3. Initial error rates of 1O-1fi or higher were marked as x.

4. Lifespan: 80° C., 95% RH, and those whose error rate is twice the initial value after being left for 100 hours are marked as “×”.

The substrate treated as described above was placed in a vacuum deposition apparatus, and a recording film having an average composition of Te 90 Se 1o was deposited to a thickness of about 30 nm on the surface of the substrate to obtain a single-sided disk.

Next, place two single-sided discs with the recording film inside and the thickness is 1.
An information recording medium having a hollow part was obtained by adhering with an epoxy adhesive through a spacer member having a width of M (10 mm).

Recording on the information recording medium created as described above was performed as follows. First, the information recording medium is rotated at 24 rpm, and a semiconductor laser beam with a wavelength of 830 nm is traced along the glass substrate with a lens and focused onto the recording film. The laser beam is controlled to be kept above the groove by the diffraction effect from the 1/8 wavelength deep groove, and the output of the laser beam is increased at a predetermined position to change the intensity according to the signal to perform recording. Strong laser beam
A hole is made in the e,Se-based recording film and recording is performed.

Reproduction of recording can be carried out in the same manner as during recording by keeping the light spot on a predetermined track 7 and detecting the intensity of the reflected light with a power that does not cause recording.

Examples 1-3. The information recording media of Comparative Examples 1 to 3 were heated to 80°C9.
A recording/reproduction experiment was conducted after leaving the sample at 5-inch RH for 1,000 hours. As shown in Table 1, in Examples 1 to 3, no increase in error rate was observed compared to the initial stage. In Comparative Examples 1 and 2, the error rate increased significantly. In Comparative Example 3, the initial error rate was high.

As described above, the information recording medium in which a recording film is formed according to the present invention has excellent moisture resistance and has a long recording and reproducing life.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an information recording medium, and FIG. 2 is a schematic diagram of a gas plasma processing apparatus. 1... Plastic base 2... Spacing member 3'' tracking groove 4... Information hole 5... Hollow part
6...Recording film 7...High frequency generation coil 8
... Cylinder 9 ... Gas supply pipe 10 ... Hole 11
... Vacuum pump 12 ... Sealing door 13 ... Base figure 1 Δ・2 area

Claims (1)

[Claims] 1. There is a gap between the opposing surfaces of two transparent plastic substrates that can be rotated, and the substrates are joined together so that this gap is cut off from the i-field, thereby sealing the substrate. A casing made of a combined body forming a gap space, and a surface pressure of the base facing the sealed space inside the casing. The production of an information recording medium comprising a recording film containing Se as an essential component is characterized by comprising the steps of exposing the surface of the substrate to a gas plasma atmosphere under reduced pressure, and depositing the recording film on the surface of the substrate. A method of forming a recording film on the substrate surface of an information recording medium.