JPH0298847A - Manufacture of information recording medium - Google Patents

Abstract

PURPOSE:To shorten the time required for manufacture and to obtain an information recording medium which has a high reflection factor and high C/N by forming a layer of metal where information is writable and readable on a substrate by the irradiation of laser beam, and then heating and crystallizing the metal layer at high frequency. CONSTITUTION:The medium consists of a cylinder 1 of quartz for containing a heating material and a copper wire 2 wound spirally around the cylinder so as to apply a high frequency. A sample holder 4 where optical disks 3 are arranged is inserted in the cylinder 1 of quartz for heating and in this state, a high frequency current is applied to the copper wire 2 to heat the metal layer which has relatively high sensitivity suitable for an optical disk and is in an amorphous state at the high frequency, thereby changing the layer into the amorphous state in a short time. Consequently, the information recording medium which has the high reflection factor and high C/N is obtained in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a method of manufacturing an information recording medium used for recording and reproducing information using light.

[Technical Background of the Invention 1] In recent years, information recording media that use high energy density beams such as laser light have been developed and put into practical use. This information recording medium is called an optical disk, and includes video disks, audio disks, and large-capacity static IFs.
It can be used as an image file and a disk ψ memory for a large capacity computer.

The information recording medium is basically 4Ii construction, and is made of plastic,
It has a disc-shaped transparent substrate made of glass or the like, and a recording layer sunk into the disc-shaped transparent substrate. As material 1 for the recording layer, B
Metals such as i, Sn, In, TeC9 or gold metal are used. Substrate surface uli on the side where the recording layer is provided
In general, the undercoat layer or intermediate layer made of a polymeric substance is usually destroyed due to changes in the surface properties of the substrate, the adhesive strength with the recording layer, or the sensitivity. ing. In addition, in order to protect the recording layer, information recording media with a sandwich structure have been proposed, in which a protective layer is used for the recording layer, or two plates are stacked together with the recording layer inside. It is used.

Information can be written to a recording medium using, for example, a laser.
The irradiated portion of the recording layer absorbs the light and locally raises the temperature to 1: 'yl.
As a result, information is recorded by causing a physical change, such as a bit shape 1&, or a chemical change, such as a phase change, to change its a priori characteristics.

Reading of information from an optical disk is also performed by irradiating the optical disk with a laser beam, and information 11r is generated by detecting reflected light or transmitted light according to changes in the optical characteristics of the recording layer.

The recording layer of such an optical disc is made by depositing the material in a vacuum
Although it may become crystalline immediately after layer formation depending on the composition of the recording layer or the deposition conditions, there are many cases where it is in an amorphous state or a mixture of both states. The recording layer in the cliff quality state is generally crystallized by heat treatment and then used as the recording layer. For example, Se, Te and other metals (In, Pb, S
It is described in Jikai IV (No. 57-66998) that heat treatment is performed on a recording layer made of a material (selected from n, etc.).

I-If thermal treatment is not performed, most of the recording layer is in an amorphous state, so it is difficult to obtain a high reflectance.A recording layer with such a low reflectance is sufficiently high. There is a problem that it is difficult to obtain C/N.

However, the crystallization process by heat treatment takes several hours or more, which is extremely disadvantageous in manufacturing optical disks.

If the heating temperature is increased to shorten this processing time,
Distortion of the substrate occurs, which adversely affects the recording and reproducing characteristics of the information recording medium.

[Objective 1 of the Invention] An object of the present invention is to provide a novel method for manufacturing an information recording medium.

Furthermore, one object of the undeveloped IJJ is to provide a manufacturing method that can significantly shorten the time required to manufacture an information recording medium with high reflectance.

[Summary of the Invention] The present invention forms a layer made of a metal on which information can be read and interpreted by laser beam irradiation on the substrate-E, and then crystallizes the metal layer by high-frequency heating. There is a method for manufacturing an information recording medium comprising the following steps.

Preferred embodiments of the method for manufacturing an information recording medium of the present invention are as follows.

The t-+1 metal layer is Te, TeSe, TeS.

InGe, InGe5 and TeSeM (however, TeSe
In M, Te is 50 to 90% by weight.

Se has a value in the range of 5 to 40% by weight, M has a value in the range of 1 to 30% by weight, and 1M is Pb, In, Ge, S.

Sb, As, Bi, Sn, An, Ga, TJI, Zn,
Cd, Au, Ag, Cu, Ni, Pd, Rh, Cr, M
A method for manufacturing a bipedal information recording medium, characterized in that the layer is made of a material selected from O, W, and Ta.

2. The metal layer is TeSe, InGe5 or Te5e
Pb (However, in Te5ePb, Te is 50 to 90
% by weight, Se by 6 to 40% by weight, and Pb by weight from 1 to 30% by weight, in the range of 11ii).

3.-1- High frequency heating is 0,5kHz-2,45
A method for manufacturing an information recording medium, characterized in that the process is carried out using a frequency in the GHz range and within a time period in the range of 10 seconds to 10 minutes.

4. A method for producing a bipedal information recording medium, characterized in that the metal layer is formed by co-evaporating or co-buttering the metal.

[9iIJ) Effect J The information recording medium obtained by the method for producing undeveloped IJ is as follows:
1- A recording layer made of a metal is provided and has a high reflectance. That is, by high-frequency heating a metal layer in an amorphous state that has relatively high sensitivity and is suitable for optical disks, it can be changed from an amorphous state to a crystalline state in an extremely short time. The recording layer thus obtained has a sufficiently high reflection (high A<C/N).

Therefore, by using the manufacturing method of IJ7, an information recording medium with high reflectance and high C/N can be obtained.

[Detailed Description of the Invention] A method for creating an information recording medium 9a of unissued 11 is carried out, for example, as follows.

The substrate used in the present invention can be arbitrarily selected from various materials used as substrates for conventional information recording media. Optical properties, flatness, processability of the substrate,
2 from the viewpoint of ease of handling, stability over time, manufacturing cost, etc.
Examples of substrate materials include glass such as soda lime glass; acrylic resins such as cell cast polymethyl methacrylate and injection molded polymethyl methacrylate; vinyl chloride resins such as polyvinyl chloride and vinyl chloride copolymers; epoxy resins; polyethylene terephthalate. etc. polyesters;
Polyimides; mention may be made of polycarbonates and amorphous polyolefins. Among these, preferred are polymethyl methacrylate, polycarbonate, epoxy resin, amorphous polyolefin and polyethylene terephthalate, with polycarbonate being particularly preferred.

The surface of the substrate on which the recording layer is provided has improved flatness,
An undercoat layer may be provided for the purpose of improving adhesive strength and preventing deterioration of the recording layer. Examples of materials for the undercoat layer include polymethyl meccrylate, acrylic acid/methacrylic acid copolymer .

Polymer substances such as nitrocellulose, polyethylene, polypropylene, and polycarbonate; organic substances such as silane coupling agents; and inorganic oxides (S io 2 ,
Examples include inorganic substances such as Al 203) and inorganic fluorides (MgF2).

In the case of a glass substrate, in order to prevent adverse effects on the recording layer due to alkali metal ions and alkaline earth metal ions liberated from the substrate, wood-philic groups such as styrene/maleic anhydride copolymer and/or maleic anhydride are added. Preferably, a subbing layer made of a polymer having acid groups is provided.

The undercoat layer can be formed by, for example, dissolving or dispersing the above-mentioned substance in a suitable solvent and then applying this coating solution to the substrate surface by a coating method such as spin code, tip coat, extrusion coat, etc. .

Further, on the substrate, a pre-groove layer may be provided for the purpose of tracking grooves, or a pre-pit layer may be provided for the purpose of forming unevenness representing information such as address signals, etc. Materials for the pre-groove layer etc. As the initiator, a mixture of at least one monomer (or oligomer) of acrylic acid monoester, diester, triester, and tetraester and a photopolymerization initiator can be used.

The thickness of the pre-groove layer is generally 0.05~! 00
It is in the range of μm, preferably in the range of 0.1 to 50 gm. Furthermore, in the case of a plastic substrate, pregrooves or the like may be formed directly on the substrate surface.

An intermediate layer of chlorinated polyolefin, nitrocellulose, polystyrene, or fluororesin resin may be provided on the substrate of the information recording medium of the present invention (via a pregroove layer or an undercoat layer if desired).

Preferably 11! For example, when a chlorinated polyolefin layer is provided, which is a layer made of chlorinated polyolefin or fluororesin, this can reduce the loss of thermal energy due to laser beam irradiation from the recording layer to the substrate due to thermal conduction. Since gas is generated from the irradiated portion of the chlorinated polyolefin layer, it is easy to form bits, thereby increasing recording sensitivity and reducing reading errors (pit error rate).

The chlorinated polyolefin layer can be provided by dissolving the above-mentioned chlorinated polyolefin in a solvent to prepare a coating solution, and then applying and drying this coating solution onto the substrate (via an undercoat layer, etc. if desired). .

As a coating method, a spray method, a spin code method, a dip method, a roll coating method, a blade coating method, a doctor roll method, a screen printing method, etc. can be used.

Further, the fluororesin layer can be formed by, for example, sputtering polytetrafluoroethylene (eg, Teflon (manufactured by DuPont)) onto the substrate.

The layer thickness of the chlorinated polyolefin layer and the fluorine resin layer is generally in the range of 10 to 1000, preferably 1
It is in the range of 00 to 500 seconds.

A recording layer is provided on the intermediate layer such as the above-mentioned fluororesin layer or on the substrate L (via a pregroove layer or the like if desired).

The recording layer of the present invention can be obtained by forming a layer made of metal on a substrate and then crystallizing the gold layer by high-frequency heating. The recording layer thus obtained is a metal layer whose reflectance has been changed to a sufficiently high reflectance.

”-Ashikin f! The layer material may be any material that can be crystallized by heating, such as metals, semimetals, metal sulfides
The oxides and combinations thereof are not particularly limited.

Preferred examples of the material for the metal layer include Te and TeS.
e, TeS, InGe, InGe5 and TeSeM (
However, it is subject to T e S e M.

Te is 50 to 90% by weight (particularly preferably 60 to 85% by weight), and Se is 5 to 40% by weight (particularly preferably 7 to 2% by weight).
M is a value in the range of 1 to 3017j (particularly preferably 2 to 10% by weight), and M is P
b, In, Ge, S, Sb, As, Bi, Sn, AU
, Ga, T1. Zn.

Cd, Au, Ag, Cu, Ni, Pd, Rh.

Representing a kind of metal selected from Cr, MOLW and Ta) can be mentioned. Particularly preferably TeS
e, InGe5 or Te5ePb (however, Te5eP
In b, Te is 50-90%, Se is 6-40%
% by weight and Pb ranges from 1 to 30% by weight)
can be mentioned.

1-. The metal layer serving as the recording layer is formed on the substrate by a known method such as vapor deposition, sputtering, or ion blasting using the above-mentioned recording layer material. to use.

Co-evaporation or co-sputtering is preferably used.

The thickness of the metal layer (recording layer) formed in this way is
From the viewpoint of ease of writing information and reflectance, 1.
The range is preferably from 00 to 3000X, particularly preferably,
It is in the range of 200-1200X.

The reason for this is that the above-mentioned metals, metal layers formed by vacuum deposition etc. in combination with 4S and one or more metals, exhibit a relatively high Q8 degree, but have a low 1 reflectance. This is because most of the deposited metal layer is in an amorphous state. A recording layer with such a low reflectance cannot provide excellent recording and reproducing characteristics such as a sufficiently high C/N.

The present inventors have known that the phase state of the metal layer changes from an amorphous state to a crystalline state by S treatment, and the reflectance increases.

It has been found that by high-frequency heating the metal layer, it is possible to change it from an amorphous state to a crystalline state in an extremely short period of time, thereby obtaining a crystallized metal layer having a high reflectance. The recording layer thus obtained has a high reflectance because the crystallization has progressed uniformly and sufficiently, like a layer that has been sufficiently heat-treated, and therefore can have a high C/N ratio.

In the L information recording medium, by using a recording layer with a high C/N ratio and one reflection, information is recorded not by phase change but by bit formation. It will be done.

Book 15il! In order to increase the reflectance of the metal layer (change it from a non-1i7J'f!1 state to a crystalline state) as described above, the metal layer is subjected to high-frequency heat treatment. High frequency heating is performed using gold kf formed by the above aR etc.
, is carried out by placing the layer in a high frequency heating furnace. In general, high-frequency heating is a method of heating a material placed inside a coil by passing a high-frequency current through the coil. In the case of a conductor such as the recording layer mentioned above, it is heated by eddy currents generated by electromagnetic induction, and dielectric materials such as plastic materials are heated. It is heated slowly due to dielectric loss.

A high-frequency heating furnace 1 has an appearance as shown in the fjSf diagram, for example, and consists of a quartz cylinder 1 for housing a heating material and a copper wire 2 wound around the quartz cylinder 1 for applying high-frequency waves in a spiral shape. ing. A sample holder 4 in which optical disks 3 are lined up is inserted into this quartz tube 1 for heating, and in this state high-frequency heating is carried out by passing a high-frequency current through the copper wire.

The conditions for high frequency heating are 0.5kHz to 2.45G.
It is generally carried out for a time in the range of 10 seconds to 10 minutes, preferably 1-10k, using a current with a frequency in the range of Hz.
It is carried out at a frequency in the range of Hz for a time in the range of 1 to 10 minutes.

The power used for high frequency heating is generally 100W to 1O
It is within the range of kW.

The recording layer of the present invention can be formed in this manner.

On the recording layer, as part of the recording layer, an oxide layer or a nitride layer, or silicon dioxide of the recording layer is provided for the purpose of improving recording characteristics and durability.

A layer made of an inorganic substance such as tin oxide, magnesium fluoride, tellurium oxide, or antimony oxide may be provided, and these can be provided by methods such as vacuum evaporation, sputtering, or coating.

It is preferable that a protective layer is provided on the recording layer. The protective layer is preferably an intermediate layer consisting of a soft protective layer made of a soft resin material and a hard protective layer made of a hard resin material. Lay it on the recording layer with the soft protective layer side facing the recording layer side. Examples of soft resin materials include polyurethane, polyvinylidene chloride, ethylene-vinyl acetate copolymer, silicone rubber, styrene-butadiene rubber, polyvinylidene chloride, and polyacrylic acid ester. Solution coating, latex coating,
It is applied to the recording layer by a method such as melt coating, and if necessary, it is subjected to treatments such as drying and heating to form a soft protective layer. The thickness of the soft protective layer is usually in the range of 100 λ to 5 pm, preferably in the range of 0.01 to 3 pm. Examples of hard resin materials include ultraviolet curing resins, thermosetting resins, etc. 6 Usually, these are applied onto the soft protective layer by methods such as solution coating, and if necessary, treatments such as ultraviolet irradiation and heating are performed. It is used as a hard protective layer. Hard maintenance! The layer thickness of the I layer is usually in the range of 0.1-10 gm,
Preferably it is in the range of 1 to 3 μm.

The surface of the substrate opposite to the side on which the recording layer is provided is coated with inorganic substances such as silicon dioxide, tin oxide, magnesium fluoride, thermoplastic resin, and optical fibers to improve scratch resistance and moisture resistance. A thin film made of a polymer material such as a curable resin is coated in a vacuum/AI! 1. It may be provided by a method such as sputtering or coating.

For laminated type information recording media.

It can be manufactured by joining two substrates having the J2 structure using an adhesive or the like. In an air sandwich type recording medium, at least one of the two disc-shaped substrates has the above-mentioned aI&, via a ring-shaped outer spacer and an inner spacer, or to one or both of the substrates. It can be manufactured by joining via provided protrusions.

Next, information can be recorded using the above information recording medium, for example, by an optical information recording method as described below.

First, while rotating the information recording medium at a constant linear velocity (or angular velocity in some cases), recording light such as semiconductor laser light is irradiated from the substrate side. Generally, the recording light is 7
A semiconductor laser beam with an oscillation wavelength in the range of 50-850 nm is used. Generally recorded with a laser power of 5-20 mW.

As a result, bits having a length of 0.70 to 4.0 pm are formed in the recording layer at intervals of 0.70 to 4.0 pm in a concentric solid shape or in a spiral shape.

When recording, it is preferable to perform tracking adjustment using a tracking pregroove. If the recording medium is provided with a pregroove, the signal can be recorded either at the bottom of the group or in the area between the groups. It's okay.

Information can be reproduced by rotating the recording medium at the same constant linear velocity as described above, irradiating semiconductor laser light from the substrate side, and detecting the reflected light.

Next, examples of the present invention will be listed. However, each of these does not limit the present invention.

[Example 1] Disc-shaped polycarbonate substrate with tracking grooves (outer diameter: 120 mm, inner diameter: 15 mm, thickness: 1.2
mm, depth 0.0mm in the range of inner diameter 45mm to outer diameter 116mm.
07JLm, $&IO, 8ILm, pitch 1.671
m grooves are provided in a spiral shape)] Second,
Sputter Teflon (manufactured by DuPont) to a layer thickness of 5
00X intermediate layer was formed 6 Then, on this intermediate layer,
A recording layer having a layer thickness of 500 layers was formed by co-sputtering Te, Se, and Pb at a ratio of 82% by weight: 12% by weight: 6% by weight, respectively.

Next, the obtained information recording medium is placed in a high frequency heating furnace,
Using a frequency of 5kHz, power of 500W for 1 minute,
Heating was performed. As a result, a crystallized recording layer was formed.

In this way, an information recording medium consisting of a substrate, an intermediate layer, and a recording layer was manufactured.

The sputtering conditions listed in L are Pelger internal pressure 10'''
Argon gas introduced at Torr, pressure after introduction = 7X10-
Torr, target distance: 5 cm.

[Comparative Example 11 Information recording medium having a crystallized recording layer in the same manner as in Example 1 except that the recording layer was not subjected to high-frequency heating but was subjected to heat treatment at 60° C. for 120 minutes. I created fiI.

[Comparative Example 2] Information recording medium having a crystallized recording layer in the same manner as in Example 1 except that the recording layer was heat treated at 60° C. for 30 minutes without high-frequency heating. was manufactured.

[Comparative Example 3] Information recording having a crystallized recording layer in the same manner as in Example 1 except that in Example 1, the recording layer was not subjected to high-frequency heating but was heated at 80° C. for 120 minutes. Media was manufactured.

[Comparative Example 4] Information recording medium having a crystallized recording layer in the same manner as in Example 1 except that the recording layer was heat treated at 80° C. for 30 minutes without high-frequency heating. was manufactured.

[Evaluation of Information Recording Medium] (1) Reflectance Reflectance was measured using a spectrophotometer model 330 (manufactured by JASCO ■). (The light used for the measurement had a wavelength of 820 mm.) 111 constant was performed before and after the high frequency heat treatment.

(2) Recording power at which C/N is maximum
Binary information was recorded using EC, and the above measurement was performed using a spectrum analyzer with a bandwidth of 30 kHz.

The above measurement results are shown in Table 1.

Table 1 Reflectance (%) Maximum C/ Before → After treatment Power (tW) Example 1 34-$42 51 Comparative example 1
33 → 38 50 2 33 Shun 42 49 3 35 → 40 514 34 Moan 4
1 50 As is clear from Table 1, Example 1. In Comparative Examples 1 and 3, high reflectance and high C/N can be obtained. However, by using the manufacturing method of the present invention, it is much more efficient than Comparative Example 1 using conventional heat treatment (
In other words, the heat treatment is performed for 120 minutes, and the high-frequency heating is performed for 1 minute.) It is possible to produce an optical disc with a high gloss and high quality.

On the other hand, Comparative Examples 2 and 3, in which the heat treatment time was short, were inferior in both reflectance and C/N compared to the above information recording medium.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the appearance of an example of a high-frequency heating furnace used in the manufacturing method of the present invention. l2 Quartz tube 2: Copper wire 3: Optical disk 4: Sample holder

Claims (1)

[Claims] 1. After forming a layer made of metal on the substrate that allows information to be written and read by irradiation with laser light,
A method for manufacturing an information recording medium, which comprises crystallizing the metal layer by high-frequency heating.