JPH027245A - Production of optical information recording medium and apparatus for producing optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain the optical information recording medium which has good recording sensitivity, high CN and low error rate by exposing an underlying film to a plasma atmosphere contg. elements such as hydrogen, oxygen, nitrogen, carbon, and halogen elements after the underlying film is formed on the signal surface of a substrate and before a recording film is formed thereon. CONSTITUTION:The underlying film 4 is formed on the signal pattern 3 forming surface of the substrate 1. This underlying film 4 is formed on an org. compd. such as polytetrafluoroethylene, guanine, hydrocarbon polymerized film or the like. The underlying film 4 is then exposed to the plasma atmosphere A contg. at least one kind of the elements selected from the hydrogen, oxygen, nitrogen, carbon, and halogen elements, by which the underlying film 4 is modified. The polymn. of the underlying film is then accelerated by the energy of the plasma A and the dangling bonds in the underlying film and the elements added in the plasma are bonded to each other, by which the dangling bonds are decreased. The chemical stability and C/N of the underlying film 4 are improved in this way and recording/reproducing errors are decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an optical information recording medium and an apparatus for manufacturing an optical information recording medium suitable for carrying out the method. The present invention relates to a method for modifying a base film in a shaped optical information recording medium, and a manufacturing apparatus equipped with a means for modifying the base film.

[Conventional technology]

Conventionally, write-once type optical information recording media in which a base film is interposed between a substrate and a recording film have been known. We proposed an optical information recording medium in which a base film made of ethylene and an organic compound such as a hydrocarbon polymer film was formed (Japanese Patent Laid-Open No. 62-219244, Japanese Patent Laid-Open No. 62-2
No. 19245, JP-A-63-25849).

Optical information recording media equipped with these base films have high recording sensitivity and can record information with small laser power. Therefore, there are advantages in that the device can be made smaller and lower in cost, the signal surface of the substrate is less likely to be damaged, and the life of the medium can be extended.

[Problem to be solved by the invention]

However, subsequent experiments revealed that this type of optical information recording medium had poor shaping properties around the edges of written pits.
Poor C/N ratio, ■ Remains of the recording film in the pit or reaction products between the recording film and the underlying film (hereinafter, both of these are referred to as "
"What's left behind?" ) remains, and in the case of a disc-shaped optical information recording medium, it has been found that during use, this residual debris moves to the outer periphery of the disk, increasing recording/reproducing errors at the outer periphery.

The present invention solves the problems of these conventional techniques and provides a method for manufacturing an optical information recording medium that has good recording sensitivity, a high CN ratio, and a low error rate, and an optical information recording medium suitable for carrying out the method. The purpose of this invention is to provide a manufacturing apparatus for the following.

[Means to solve the problem]

In order to achieve the above object, the present invention forms a base film on a signal surface of a substrate, and then, before forming a recording film, selects the base film from hydrogen, oxygen, nitrogen, carbon, and halogen elements. The manufacturing method is characterized in that it is exposed to a plasma atmosphere containing at least one type of element.

Further, a plasma processing chamber connected to at least one type of introduced gas source selected from hydrogen, oxygen, nitrogen, carbon, and halogen elements is interposed between the base film forming chamber and the recording film forming chamber. This is a feature on the device.

[Effect]

Generally, methods such as vacuum evaporation, sputtering, and plasma polymerization are used to form the base film, but the composition of the base film formed by these methods is chemically different from that of the pure starting material. and have significantly different physical properties. For example, pure polytetrafluoroethylene has two fluorines bonded to one carbon, but the base film obtained by sputtering this pure polytetrafluoroethylene is When analyzed by photoelectron analysis method), the ratio of the amount of carbon element (C) to the amount of fluorine element (F) (
F/C) is 1.7 to 1.9. However, F/C
The variation in the numerical value depends on the sputtering conditions.

Furthermore, free elemental fluorine is adsorbed on the surface of the base film.

Further, as measured by differential scanning calorimetry, the melting point of pure polytetrafluoroethylene is 325°C, whereas the melting point of the base film is 219°4°C.

From these data, the following can be inferred.

In other words, the base film obtained by sputtering polytetrafluoroethylene is not in a stable stoichiometric state;
It is in an active state. For this reason, if a recording film is directly laminated on such a base film.

Phenomena occur in which the underlayer and the recording film react to produce reaction products, and active fluorine attached to the surface of the underlayer is incorporated into the recording film. A recording film incorporating the reaction product or fluorine has different physical and chemical properties than a pure recording film, such as a higher melting point. As described above, the existence of portions with different physical and chemical properties in the recording film causes problems such as the peripheral edges of pits not being neatly shaped during recording and residue remaining.

On the other hand, when a chemically unstable base layer is exposed to a plasma atmosphere, the energy promotes polymerization of the base film. Furthermore, when at least one element selected from hydrogen, oxygen, nitrogen, carbon, and halogen elements is added to the plasma, these elements combine with dangling bonds in the base film, reducing the number of dangling bonds.

As a result, the chemical stability of the base film is improved, reaction products between the base film and the recording film are reduced, the homogeneity of the recording film is maintained, the shaping of pits is improved, and residual will be reduced.

〔Example〕

First, an outline of the present invention will be explained based on FIGS. 1 to 4.

The method for manufacturing an optical information recording medium according to the present invention mainly includes:
It consists of a step of producing a substrate, a step of forming a base film on the substrate, a step of modifying the base film, and a step of laminating a recording film on the modified base film.

The substrate is formed to have a desired outer diameter and dimensions using a transparent ceramic such as glass or a transparent polymeric material such as polycarbonate, polymethyl methacrylate, polymethyl pentene, or epoxy.

A signal pattern such as a pre-groove for guiding a radiation beam for recording/reproduction and a pre-pit corresponding to an address signal is transferred onto one side of the disc.

The method for molding the substrate and the method for transferring the signal pattern include:
Appropriate means are adopted depending on the substrate material.

For example, for ceramic substrates and thermosetting resin substrates such as epoxy, photocuring is performed between the substrate formed into a flat plate and a mold called a stamper in which an inverted pattern of the desired signal pattern is formed. The so-called 2P method (photocurable resin method) is particularly suitable, in which a resin layer is spread and cured, and then a resin layer to which a signal pattern is transferred is provided on the substrate side. Figure 1 (
A) is a sectional view of this type of substrate, in which a signal pattern 3 is formed on one side of a substrate 1 with a resin layer 2 interposed therebetween.

On the other hand, for thermoplastic resin substrates such as polycarbonate and polymethyl methacrylate, an injection molding method in which a molten resin is injected into a mold in which one side of a cavity is formed by the stamper is suitable.

FIG. 1(b) is a cross-sectional view of this type of substrate, and the substrate 1
A signal pattern 3 is directly formed on one side of the .

Next, as shown in FIG. 2, a base film 4 is formed on the surface of the substrate 1 on which the signal pattern 3 is formed. The base film 4 is formed of an organic compound such as polytetrafluoroethylene, guanine, or a hydrocarbon polymer film. The method for forming the base film 4 may be any known physical or chemical film formation method, such as a vacuum evaporation method, a sputtering method, or a plasma polymerization method, that is compatible with the base film material. An appropriate film forming method is adopted.

Next, as shown in FIG. 3, the base film 4 is coated with hydrogen, '
The underlayer v4 is modified by exposing it to a plasma atmosphere A containing at least one element selected from N1 elements, nitrogen, carbon, and halogen elements. In this case, in order not to deteriorate the purity of the base film, it is possible to expose it to a plasma atmosphere containing at least one element constituting the base film and selected from the above-mentioned group of elements.

In addition, in the case of a base film formed by sputtering polytetrafluoroethylene, a plasma atmosphere containing either hydrogen or fluorine is most effective in improving pit shaping and reducing error rates. be.

In this way, the energy of the plasma A promotes the polymerization of the base film, and the dangling bonds in the base film are combined with the elements added to the plasma to reduce the number of dangling bonds, and the base film 4 chemical stability is improved. Therefore, reaction products between the recording film and the underlying film,
The incorporation of elements constituting the base film material into the recording film is reduced, the pit shaping is improved, the C/N ratio is improved, and the generation of residual debris is suppressed, resulting in improved recording/reproduction. Errors are reduced.

Finally, as shown in FIG. 4, a recording film 5 is laminated on the base film 4 modified as described above to form an optical recording single plate. Recording film materials include, for example, low-melting point alloys containing tellurium as a main component, cyanine-based or phthalocyanine-based organic dyes, and so-called write-once heat mode recording that undergoes thermal deformation when irradiated with a recording radiation beam. material is used. As a method for forming the recording film 5, any known film forming method such as a spin coating method, a vacuum evaporation method, a sputtering method, an electron beam method, etc. can be used.

After the optical recording single plate is formed as described above, a preservation film is provided on the surface of the recording film 5, or the recording single plates are bonded together to form a double-sided recording type optical information recording medium. Such measures can be taken at will.

Hereinafter, more specific examples will be shown and the effects of the present invention will be described.

First Example A base film made of polytetrafluoroethylene was formed to a thickness of 400 mm by sputtering on the signal surface of a polycarbonate substrate molded by injection molding. The conditions for forming the base film are that the target is pure polytetrafluoroethylene, the sputtering gas is pure argon, and the sputtering gas pressure is 4.
X 10-3 mbar, input power is high frequency 450W.

Next, the substrate on which the base film was formed was transferred to a plasma processing chamber, and the base film was exposed to a plasma atmosphere containing argon gas to which 10% hydrogen was added. Other plasma treatment conditions were as follows: gas pressure was adjusted to 5 x 10-3 mbar, and input power was adjusted to 200W.

Furthermore, a recording film of tellurium-selenium-lead alloy was formed to a thickness of about 210 mm on the base film subjected to the plasma treatment as described above by sputtering. The conditions for forming the recording film were: the target was a tellurium-selenium-lead alloy, the sputtering gas was pure argon, and the sputtering gas pressure was 5×1O-3II.
lbar, and the input power is high frequency 370W.

Finally, in order to crystallize the recording film and stabilize the reflectance, baking treatment was performed at 80° C. for 1 hour in air.

Second Example After forming a base film under the same sputtering conditions as in the first example, the base film was transferred to a plasma processing chamber and exposed to a plasma atmosphere containing CFa gas. The plasma treatment conditions at this time were a gas pressure of 3 x 10-3 m.
bar, and the input power was adjusted to 350W.

Next, a recording film was laminated on this base film by sputtering. The sputtering conditions for the recording film are also the same as in the first embodiment.

Comparative Example> After forming a base film on the signal surface of a substrate, a recording film was directly laminated on the base film without performing plasma treatment.

The conditions for forming the substrate and the sputtering conditions for the base film and recording film are the same as in the first embodiment.

Using a scanning electron microscope, the first example and the second example were
When the pits written on the optical information recording media of the examples were observed, the shape of the pit periphery was smooth in all cases, and almost no residue was observed.

Also, using the above-mentioned Q/playback device, the first. When we measured the C/N ratio of the optical information recording media of the second example and the comparative example and the change in the error rate at the outer periphery due to writing to the inner and middle periphery of the optical information recording medium, the following table shows: The results were obtained.

As is clear from the above table, the optical information recording medium according to the present invention has a lower noise level and a higher C/N ratio than the optical information recording medium of the comparative example. Further, while the optical information recording medium of the comparative example has an increased error rate in the outer peripheral area due to writing to the inner peripheral area and the middle peripheral area, the error rate does not increase in any of the optical information recording media of the present invention.

Next, a film forming apparatus applied to the implementation of the present invention will be described.

As shown in FIG. 5, the film forming apparatus of the present invention includes a preliminary exhaust chamber 11, a base film forming chamber 12, plasma-treated water 13,
The recording film forming chamber 14 and the take-out chamber 15 are connected to a buffer 16.
~19, and the preliminary exhaust chamber 11 and the first
gate valves 20 and 21 between the second buffer 19 and the second buffer 19 and the take-out chamber 15, respectively.
is interposed. The base film forming chamber 12 and the recording film forming chamber 14 can be formed using any known physical or chemical film forming apparatus such as a sputtering apparatus, a vacuum evaporation apparatus, or a plasma polymerization apparatus. This film forming apparatus is equipped with a substrate carrier (not shown in FIG. 5), and the substrates stored in the preliminary evacuation chamber 11 are sequentially passed through each chamber 12, 13, and 14 to a take-out chamber. It is designed to transport up to 15.

FIG. 6 is a configuration diagram of the plasma processing chamber 13, including an exhaust port 22 for discharging gas in the plasma processing chamber 13, and an element selected from hydrogen, V1 element, nitrogen, carbon, and halogen element in the plasma processing chamber 13. A gas inlet 23 is provided for introducing at least one type of gas. Also, inside the plasma processing chamber 13, a carrier 2 for transporting the substrate 1 is provided.
4 and a counter electrode 25 are arranged, and a high frequency power source 26 is connected to the carrier 24.

When manufacturing an optical information recording medium using this apparatus, the base film forming chamber 12, the plasma processing chamber 13. Record g
Film formation chamber 14. Removal chamber 15 and each buffer 16
~19 is evacuated to a high degree of vacuum, and the gate valve 20.2 is
1 is closed.

At the same time, the carrier 24 is returned to the preliminary exhaust chamber 11.

Next, the substrate 1 is carried into the pre-evacuation chamber 11, the substrate is attached to the carrier 24, and the pre-evacuation chamber 11 is evacuated to a high degree of vacuum.

When the pre-evacuation chamber 11 is evacuated to a predetermined degree of vacuum, the first gate valve 20 is opened, the substrate 1 is carried from the buffer 16 into the base film forming chamber 12, and a desired base film is formed.

After forming the base film, the carrier 24 is driven to carry the substrate 1 into the plasma processing chamber 13. Here, while introducing a desired gas through the gas inlet 23, the gas inside the plasma processing chamber 13 is discharged through the exhaust port 22 to adjust the gas pressure inside the plasma processing chamber 13. After that, the carrier 24 is
Electric power is supplied to generate plasma between the electrode 25 and the counter electrode 25, and the base film is irradiated with the plasma containing the introduced gas.

After the base film is plasma-treated, the carrier 24 is driven to carry the substrate 1 into the recording film forming chamber 14, and a desired recording film is laminated on the base film.

After forming the recording film, open the second gate valve 21 and remove the substrate l.
is carried into the take-out chamber 15, the pressure inside the take-out chamber 15 is returned to normal pressure, and the substrate l on which the base film and recording film are formed is taken out.

In the film forming apparatus described above, the plasma processing chamber 13 is provided between the base film forming chamber 12 and the recording film forming chamber 14, so that the film formation of the base film, the plasma treatment of the base film, and the film formation of the recording film are performed in a series. It can be carried out in the following steps and has good productivity.

〔Effect of the invention〕

As explained above, in the method for manufacturing an optical information recording medium of the present invention, after forming the base film and before laminating the recording film,
The base film is hydrogen, oxygen, nitrogen, and carbon.

Since the base film is exposed to a plasma atmosphere containing at least one element selected from halogen elements, the chemical stability of the base film is improved and the recording film is not corroded. Therefore, the shaping ability of the pits is improved and the CZN ratio is improved, and the amount of residue generated during pit formation is significantly reduced, thereby improving the error rate.

Further, the film forming apparatus of the present invention includes a plasma processing chamber between the base film forming chamber and the recording film forming chamber.

Formation of the base film, plasma treatment of the base film, and film formation of the recording film can be performed in a series of steps, resulting in good productivity.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams for explaining the method for manufacturing an optical information recording medium according to the present invention, FIG. 5 is a schematic diagram of a film forming apparatus according to the present invention, and FIG. 6 is a diagram showing the equipment for the film forming apparatus. FIG. 1: Substrate, 2: Resin layer, 3: Signal pattern, 4: Base layer, 5: Recording film, A: Plasma atmosphere, 11: Preliminary evacuation chamber, 12: Base film formation chamber, 13: Plasma processing chamber, 14
: recording film forming chamber, 15: take-out chamber, 16-19: buffer, 20, 21: gate valve, 22: discharge port, 23
: Gas inlet, 24: Carrier, 25: Counter electrode, 26
: High frequency power supply. (C) Figure 3

Claims (5)

[Claims] (1) In a method for manufacturing an optical information recording medium in which a base film and a recording film are sequentially laminated on the signal surface of a substrate, after forming the base film, the base film is coated with hydrogen, oxygen, nitrogen, carbon, halogen, etc. 1. A method for manufacturing an optical information recording medium, comprising: exposing the medium to a plasma atmosphere containing at least one element selected from elements; and then laminating the recording film on the plasma-treated base film. (2) The method for manufacturing an optical information recording medium according to claim 1, wherein the base film is formed by a film forming method selected from a sputtering method, a vacuum evaporation method, and a plasma polymerization method. A method for manufacturing an information recording medium. (3) The method for manufacturing an optical information recording medium according to claim 1, wherein the base film is formed of an organic compound containing carbon and a halogen element as main components. . (4) In the method for manufacturing an optical information recording medium according to claim 1, after forming a base film made of polytetrafluoroethylene on the substrate by sputtering, the base film is coated with one of hydrogen and fluorine. A method for manufacturing an optical information recording medium, which comprises exposing the medium to a plasma atmosphere containing. (5) In a film forming apparatus for manufacturing an optical information recording medium, which includes at least a base film forming chamber and a recording film forming chamber, hydrogen, oxygen, nitrogen,
1. A film forming apparatus for manufacturing an optical information recording medium, comprising a plasma processing chamber connected to at least one type of introduced gas source selected from carbon and halogen elements.