JPH04177638A - Manufacture of optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium having high productivity and high reliability easily by coating only a recordable region in irregularities formed to the recording film of a glass original sheet with organic matter. CONSTITUTION:A smoothed glass surface is coated with a photo-resist film as a recording film, and a glass original sheet with the recording film is acquired through heat treatment. Laser beams are converged to the glass original sheet by using an optical modulator, and intensity-modulated by an information signal, and the intensity-modulated laser beams are sensitized as irregularities corresponding to a ROM region and a recordable region as feeble light. Irregularities are formed through developing treatment. Only a RAM region in irregularities shaped to the recording film is coated with organic matter, and the pit of the ROM region and the depth of the tracking groove of the RAM region is made to differ. A specified stamper is formed through processes such as surface conductivity-change treatment, electroforming, peeling, etc. Injection molding is conducted on the basis of the stamper. Accordingly, a desired recording medium is obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an optical information recording medium, particularly a ROM area which is a read-only area in which information is recorded in advance, and a ROM area in which information can be written at any time or additionally. The present invention relates to a method for manufacturing a write-once optical information recording medium, which has a RAM area which is a recordable area where data can be written, and is compatible with compact discs.

(Prior Art) In recent years, as the demand for recording various information signals at high recording densities has increased, it has become necessary to record high-density information signals using information recording media made based on various structural and operating principles. Density recording and playback is becoming more common,
For example, an information signal may be recorded by forming unevenness on the signal surface of an information recording medium according to the information signal, and the recorded information signal may be reproduced by optical means, or a change in capacitance value may be used. Recording and reproducing apparatuses that perform playback based on the detection of signals have already been put into practical use for recording and playing back video signals and audio signals.

In addition, in order to meet the demands for high-density recording and reproduction in various technical fields, by irradiating the recording layer of the information recording medium with a beam whose intensity is modulated by the information signal, the recording layer of the information recording medium can respond to the information signal. Research has also begun on information recording media in which information signals are recorded by causing physical or chemical changes, but in recent years, it has become easier to obtain semiconductor lasers that operate stably. As a result, various optical recording media (hereinafter sometimes referred to as optical disks) that use laser light to perform high-density recording and reproduction have already been put into practical use, or are on the verge of being put into practical use. It is well known that research and development is currently underway.

In other words, recorded optical discs (read-only optical discs) that are mass-copied from master discs on which information signals are recorded using bits formed as geometrical four parts or convex parts are, for example, video discs or compact discs. etc., and are beginning to become popular in ordinary households.
Optical discs that allow the user to record data only once (write-once optical discs) and erasable optical discs are being actively researched and developed for practical use in office file memories and other applications1). .

By the way, compact discs, which are known as an information recording medium in which information signals are recorded in a powerful and high-density manner by an array of bits corresponding to the information signals on the signal surface of the information recording medium, are capable of transmitting light of 780 nm. An information signal is recorded on the signal surface G by an array of bits set in a specific relationship with respect to the wavelength and has a depth of u', and the entire surface of the signal surface is covered with a thin film such as aluminum. The reflectance of the land portion on the signal surface is 70% to 90% for light with a wavelength of 780 nm.
The information signal is read out from the signal surface of the information recording medium using a spot of light having a wavelength of 780 nm b).

When reading an information signal from a compact disc as mentioned above, the amount of light reflected from the bit part on the signal surface is different from the land part as a result of light interference occurring at the focus part. This is done by taking advantage of the fact that the amount of light is reduced compared to the amount of reflected light, and
Tracking error information is also obtained using the difference between the amount of light reflected from the recorded trace portion and the amount of reflected light from the land portion.

Now, with the spread of the above-mentioned compact disc, an optical disc that is compatible with a compact disc and can be played using a compact disc player, for example, has a recorded area for playback only (hereinafter referred to as ROM
Area: Read-only memory area...
) and a recording area that can be used as a write-once optical disc (hereinafter referred to as RAM area).
・Various proposals have been made regarding write-once optical discs with random access (sometimes referred to as memory areas), or optical discs whose entire surface is a recording area. However, in an optical disk having a configuration in which a RAM area is provided as described above, a guide groove for tracking is provided in a transparent substrate so that tracking control is performed even during recording.

By the way, optical discs that are compatible with compact discs must, of course, comply with the various playback standards established for compact discs, such as reflectance, modulation degree of high-frequency signals, and symmetry of high-frequency signals. The optical disc must satisfy standard values regarding performance, tracking signal output, crosstalk, etc., but it is also important to obtain a write-once optical disc that has satisfactory compatibility with various standards regarding playback on compact discs. In this case, various standards related to playback on compact discs that are particularly problematic include reflectance, modulation degree of high frequency signals, tracking signal output, etc.

Here, when attempting to configure a write-once optical disc that is compatible with compact discs, it is necessary to refer to the various standards regarding reflectance, modulation degree of high-frequency signals, tracking signal output, etc. stipulated for the above-mentioned compact discs. The following is an overview of the problems that arise when constructing a write-once optical disc that satisfies the requirements.

First, the standard value for reflectance on compact discs is that the wavelength is 780 nm from the readout side of the optical disc.
The optical disc is required to have a reflectance of 70% or more when viewed from the readout side when a laser beam of Considering only the reflection loss on the surface, the reflectance on the read side of the optical disc can be reduced to 7.
In order to achieve 0% or more, the reflectance of the metal reflective film must be at least 80% or more.

It is well known that compact discs use an aluminum reflective film that exhibits a reflectance of 80% or more, satisfying the standard value for reflectance.

However, in write-once optical discs, when recording is performed on the recording film, energy for recording is absorbed into the recording film, and as mentioned above, in write-once optical discs, tracking control during recording is Therefore, since the transparent substrate is provided with a guide groove for tracking control, the incident light is diffracted by the guide groove, resulting in a loss of light quantity, which reduces the reflectance on the reading side of the optical disc.・It has traditionally been difficult to achieve a standard reflectance value for discs.

In addition, when constructing a write-once optical disc that is compatible with compact discs, it is necessary to construct a write-once optical disc that can satisfy the standards for the degree of modulation of high-frequency signals stipulated for the above-mentioned compact discs. In this case, there are the following problems.

In other words, since compact discs use light diffraction by bits to read information signals, it is easy to meet the standard value for the degree of modulation of high-frequency signals, but this method has not been proposed in the past. In general write-once optical discs, recording is performed on the recording film by, for example, perforation or phase change, and the recorded information signals are read out by changes in reflectance. Therefore, the difference between the light reflectance at the land portion and the light reflectance at the recording portion (corresponding to the pit) due to the hole, t, or phase change, that is, the degree of modulation of the high-frequency signal is small. Therefore, it was not possible to meet the standards for the degree of modulation of high-frequency signals stipulated for compact discs.

In order to satisfy the compact disc standard value for the degree of modulation of high-frequency signals, even in write-once optical discs, it is necessary to read out information signals using light diffraction by pits. It is likewise considered necessary that the readout of the information signal be effected by means of a phase structure.

Next, when attempting to construct a write-once optical disc that is compatible with compact discs, it is necessary to construct a write-once optical disc that can satisfy the standards for the output level of the tracking signal stipulated for the above-mentioned compact discs. When doing so, there are the following problems.

In other words, the output level of the tracking signal on an optical disc is generally determined by the phase structure determined by the bit or the shape of the tracking guide groove provided on the transparent substrate, but even in write-once optical discs, it is necessary to satisfy other characteristics. In addition, it is necessary to ensure that the output level of the tracking signal satisfies the standard value.

However, in general write-once optical discs that have been proposed in the past, when recording is performed on the recording film by, for example, drilling holes, the shape of the guide groove for tracking is determined by the holes. Since the phase structure is disturbed, it is difficult to obtain a tracking signal with a desired output level.

Based on the explanation so far, if you are trying to configure a write-once optical disc that is compatible with compact discs,
There are many problems in ensuring that various characteristics such as light reflectance, modulation degree of high-frequency signals, and tracking signal output during playback meet the standards stipulated for compact discs, and conventional postscript methods Depending on the type of optical disc, it has been difficult to provide a write-once optical disc that is compatible with compact discs.

FIG. 5 is a longitudinal sectional view of an example configuration of an optical recording medium disk disclosed in Japanese Patent Application Laid-Open No. 2-132656.
. . . On the transparent substrate 10 made of polycarbonate resin, for example, on the side of the board where the guide groove G for tracking is provided, there is a ROM which is a read-only area.
In the area, a metal film 12 for light reflection and a protective film 13 made of, for example, an ultraviolet curable resin are sequentially deposited, and
In the RAM area, which is a recordable area, when a recording laser beam having a predetermined wavelength is irradiated onto the surface of the transparent substrate 10 on which the guide groove G for tracking is provided, the laser beam is Organic material film 11 (hereinafter referred to as organic material recording film 11) whose refractive index changes by absorbing an appropriate amount of
), a metal film 12 for light reflection, and a protective film 13 made of, for example, an ultraviolet curable resin are sequentially attached.

The ROM area in the optical recording medium disc described above has the same configuration as that of a normal compact disc, and its playback operation is well known.

In addition, the optical recording medium disk numbering RAM mentioned above
The area is on the transparent substrate 10 on which the tracking guide grooves G, G,... are provided. Recording laser beam power having a predetermined wavelength (when irradiated, the organic material recording film 11 attached to the transparent substrate 10 absorbs an appropriate amount of the laser beam, and the refractive index changes) do.

Then, guide grooves G, G, etc. for tracking in the transparent substrate 10 described above are provided, resulting in b))
The guide groove G for tracking and y-king in the transparent substrate 10 mentioned above in the case of laser light incident from one side of the board.

G... portion and the tiger// in the transparent substrate 10
The phase difference generated in the king guide grooves G, G... The substantial phase difference of the laser beam decreases due to the change in optical path length due to the difference in film thickness of the organic material recording film 11.
The phase difference value is smaller than the value of the phase difference determined by the groove shape in the organic material recording film 1 in the recorded portion.
1, the optical phase of the laser beam in the recorded portion is substantially advanced compared to the actual recorded portion, so that the reflectance of light during reproduction, To provide an optical recording medium disc whose characteristics such as the degree of modulation of a high frequency signal and the output of a tracking signal can meet the standards prescribed for compact discs, that is, a write-once optical disc compatible with compact discs. This is what made it possible.

(Problems to be Solved by the Invention) By the way, a write-once optical disc that is compatible with the previously proposed compact disc, which has the ROM area that is a read-only area and the RAM area that is a recordable area, is As shown in FIG. 5, in the ROM area, a metal film 12 for light reflection and protection by, for example, an ultraviolet curing resin are provided on the side of the transparent substrate 10 on which the guide groove G for tracking is provided. In contrast, in the RAM area, the organic material recording film 11 and the light reflecting film are deposited on the surface of the transparent substrate 10 on which the guide groove G for track tracking is provided. a metal film 12;
For example, since the structure is such that the protective film 13 made of ultraviolet curable resin is sequentially deposited, in manufacturing it, the protective film 13 made of ultraviolet curing resin is applied to the transparent substrate 10 corresponding to the ROM area by applying the spin code method. When forming the material recording film 11, the above-described organic material recording film 1 is provided in the ROM area.
1 must be prevented from forming, the boundary conditions become very strict and therefore the spacing (marked 14 in FIG. 5) with very large dimensions, e.g. Since it is necessary to provide a portion (as illustrated in FIG. 1) between the ROM area and the RAM area, there is a drawback that the total recording capacity of the optical recording medium disk is reduced.

In addition, when forming the organic material recording film 11 by applying the spin code method as described above, a ROM area is provided in the inner peripheral part of the optical recording medium disk, and a RAM area is provided in the outer peripheral part than the ROM area. In addition to the restriction that it is necessary to provide multiple RAM areas and multiple R
There are problems such as the inability to create an optical recording medium disk in which OM areas are mixed.

On the other hand, as a solution to these problems, the present applicant company has proposed in Japanese Patent Application No. 2-36190 that the recordable area is a ROM area that forms a figure 7 groove when masking and is a read-only area. Furthermore, the patent application is for an optical disc that is compatible with compact discs and has a recording layer made of an organic material formed over the entire recordable RAM area.

The fourth section is a side sectional view showing an example of the configuration of the optical disc. In addition, in the drawings, the same parts as in the prior art are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

In FIG. 4, Go is a pit formed by an information signal in the ROM area, and Ga is a tracking guide groove provided in the RAM area.

The width of the pit G0 and the guide groove Ga for tracking
The width of the pit Go in the direction perpendicular to the direction in which the E recording (track) of the optical recording medium disk extends, and the width of the track
This is the width of the guide groove Ga for linking.

A predetermined wavelength is applied to the entire area of the ROM area and RAM area of the surface of the transparent substrate 10 on which the pit G0 in the ROM area and the tracking guide groove Ga in the RAM area are provided. An organic material recording film 11 whose refractive index changes by absorbing an appropriate amount of recording laser light having a wavelength of 7g0nin, for example, is deposited using a spin code method. The organic material recording film 11 is, for example, a heat mode optical recording material using an organic dye or a material in which an organic dye is dispersed in an organic material, a photon mode optical recording material, or a heat mode and photon mode optical recording material. It is possible to use an organic optical recording material selected from among optical recording materials that use an organic dye or a material in which an organic dye is dispersed in an organic material that operates in the mode, but, for example, when the laser beam for the weight is not irradiated. For example, the real part is +2.65 and the imaginary part is -0,0.
It can be constructed using a cyanine-based organic dye material such as No. 5.

Reference numeral 12 denotes a metal film for light reflection provided on the organic material recording film 11 by applying, for example, a vapor deposition method or a sputtering method.
It is constructed using metals such as u, AI, and Cu, or alloys with high reflectance.

13 is provided on the top of this metal film 12, for example,
This is a protective film made of ultraviolet curable resin.

According to the configuration shown in FIG. 4, the ROM area and RAM area can be freely mixed, preventing a decrease in recording density, and the conventional spin code method can be used as is. Setting the drop position of the liquid is also easy.

However, with this configuration, the pit depth in the ROM area and the groove depth in the RAM area are different, making it difficult to adjust the depth of the RAM area during mastering, which complicates the mastering process. There is a problem.

The present invention was made in view of this point, and by applying an organic substance to the recordable area and changing the depth of the guide groove during mastering, molding can be performed using a stand bar formed by this manufacturing method. The coating of the recording layer on the disc made possible by the application of the entire surface spin-coding method has made it possible to easily obtain a highly productive and highly reliable optical information recording medium. The purpose of this invention is to provide a method for manufacturing a digital information recording medium.

(Means for Solving the Problem) The present invention has been made to solve the problem, and provides an optical information recording medium having a read-only area and a recordable area on the same surface of an optical information recording medium. A method for producing a medium, comprising: forming a recording film made of an organic material on a mirror-polished glass master to obtain a glass master with a recording film; a step of condensing a laser beam emitted in a state in which the intensity is modulated by an information signal, forming unevenness corresponding to the read-only area and the recordable area; The present invention provides a method for manufacturing an optical information recording medium, which comprises a step of forming an organic substance only in the recordable area of the unevenness.

(Example) FIG. 1 is a longitudinal sectional view of an optical information recording medium formed using a stamper molded by the method for manufacturing an optical information recording medium according to the present invention, and FIGS. K) is a process diagram for explaining the manufacturing method of the present invention and a partial vertical cross-sectional view of the optical information recording medium in the middle of manufacturing.

1 in FIG. 1 is a transparent substrate made of, for example, polycarbonate resin. For example, among the main surfaces of the transparent substrate 1 with a diameter of 120 mm, a ROM 1 with a radius of 25 mm to 35 mm [
In the area, there is a pit G of the CD-ROM signal with a depth of 130 nm.
0 is formed depending on the desired information. In addition, a RAM area with a radius of 35 mm to 58 mm has a depth of 50 mm.
nm, width 0.5 μm, pitch 1.6. amplitude 30 in um
An absolute time-modulated tracking guide groove Ga is formed by the nm wobbling.

A recording laser having a predetermined wavelength (for example, a wavelength of 780 nm) is installed on the entire surface of the transparent substrate 1 on which the bit G0 in the ROM area and the tracking guide groove Ga in the RAM area are provided. An organic material recording film (hereinafter sometimes simply referred to as a recording layer) 2, which absorbs an appropriate amount of the laser light and changes its refractive index when irradiated with light, is deposited and formed by a spin code method. .

As the organic material recording film 2, an indolenine cyanine dye represented by the general formula shown in FIG. 3 is used.

In the same formula, R2, R3, R4, and R5 are Cf(3-.

is either C2R5-, and R1 and R4 are C1 to C5
It is an alkyl group of
, ClO4,5bF6-.

Here, a method for attaching an indolenine cyanine dye using a spin code method will be described.

First, indolenine cyanine dyes such as those mentioned above,
A coating solution for the recording layer is prepared by dissolving 6% by weight in diacetone alcohol.

Then, this coating solution is dropped from the inside onto the transparent substrate 1, and the transparent substrate 1 is rotated at 1,500 to 3,000 rpm to shake it off, and the coating solution is recorded on a predetermined ROM or RAM area with a thickness of, for example, 50 to 200 nm. Layer 2 is formed by coating.

After drying the recording layer 2, a metal film for light reflection (hereinafter sometimes simply referred to as a reflective layer) is applied, for example, to a vapor deposition method or a sputtering method so as to cover the entire surface of the recording layer 2. )3 is attached.

The metal film 3 for light reflection may be a metal having a high reflectance in the semiconductor laser wavelength region, such as Au,
Metals such as AI, Ag, and Cu or alloys with high reflectance are used, but in this example, the reflective layer made of AU has a thickness of 50 to 70%.
It is deposited to a thickness of nm.

4, for example, an ultraviolet curable resin monomer provided over the entire upper surface of the metal film 3 is formed into a film with a thickness of, for example, 2 to 5 μm by a spin code method, and is further cured by ultraviolet irradiation. This is a protective film formed by

When this optical disc was played back on a suitable CD player, the ROM area could be played back as is, just like a normal CD.

Furthermore, when the C1 error rate, symmetry, modulation degree, etc. of the reproduced signal at this time were measured, the CD standards were satisfied in all cases. In addition, as a result of trying to record EFM modulated signals with a recording power of 6.5 to 9 mW using a laser beam with a wavelength of 78 Qnm in the RAM area, we were able to successfully record the signal, and the ROM area and the CD player were able to perform the recording successfully. I was able to reproduce it as well.

Next, the steps up to forming a stamper for forming an optical information recording medium as explained above, that is, the second method of manufacturing an optical information recording medium according to the present invention, will be described.
This will be explained with reference to Figures (A) to (K).

First, the glass master disk is polished to smooth the entire resist-coated surface. (FIGS. 2A and 2B) Next, a photoresist film to be a recording film is applied to the smoothed glass surface to a thickness of 130 nm by, for example, a spin code method.

(FIG. 2(C)) Thereafter, a heat treatment is performed so that this resist film is fixed to the glass master disc, thereby obtaining a glass master disc with a recording film. (Fig. 2 (D)) Next, laser light emitted from, for example, a gas laser is focused onto this recording film using an optical modulator (not shown), and the intensity is modulated by the information signal to be recorded. Then, it is exposed to a small amount of light as unevenness corresponding to the read-only area and the recordable area - in this case, the bits in the read-only area and the tracking groove depth in the recordable area are made the same. (For example, 115
nm to 180 nm, as an example 130 nm>-(
(FIG. 2(E)) After that, a development process is performed to form irregularities corresponding to the read-only area and the recordable area.

(Fig. 2 (F)) Next, an organic material is applied only to the recordable area of the unevenness formed on the recording film of the glass master disk, and the depth of the tracking groove in the read-only area and the recordable area are set to be different. It shall be closed. (The specific depth of the recordable area is 40 to 110
nm, and in the example, it is 55 nm. ) In this case, a 1% polyvinyl alcohol aqueous solution is used as the organic substance.

(Figure 2 (G)) Coating an organic substance on the recording film in this way is just a matter of
As mentioned above, the optical information recording medium of the present invention is premised on being compatible with compact discs, and therefore, the recordable area necessarily needs to have this level of groove depth in consideration of reflectance, etc. This is because.

Thereafter, a predetermined stamper is formed through processes such as surface conductivity treatment, electroforming, and peeling.

(Figure 2 (H)) Next, injection molding is performed based on this stamper.

(FIG. 2(1)) Through the above steps, a desired optical information recording medium can be obtained.

Note that FIG. 2(J) is an enlarged side view of FIG. 2(E) during force/setting, and FIG. 2(K) is an enlarged side view of FIG. 2(G).

(Comparative example) Next, a comparative example was prepared in order to compare the characteristics.

This comparative example uses a transparent substrate 1 that is molded using a stamper that does not apply any organic substance in the step shown in FIG. A recording layer was formed in a predetermined area by a spin code method, and a reflective layer and a protective layer were sequentially laminated in the same manner as in the above example to obtain an optical disc. This optical disk was reproduced by a CD player in the same manner as in the example, but the ROM area could be reproduced without any problem, but the RAM area could not be recorded or reproduced.

(Effects of the Invention) As detailed above, according to the method of manufacturing an optical information recording medium according to the present invention, during mastering, the depth of the guide groove is changed by applying an organic substance to the recordable area. ,
Coating a recording layer onto a disk molded using a stamper formed by this manufacturing method makes it possible to apply the highly productive spin code method, and therefore a highly reliable optical information recording medium can be obtained. It has great practical value, such as being able to

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an optical information recording medium formed using a stamper formed by the method for manufacturing an optical information recording medium according to the present invention, and FIGS. 2(A) to (K) are A process diagram for explaining the manufacturing method of the present invention and a partial vertical cross-sectional view of an optical information recording medium during the manufacturing process, and FIG. 4 and 5 are longitudinal sectional views of conventional optical information recording media, respectively. 1...Transparent substrate, 2...Recording layer, 3.
...Reflection layer, 4...Protective layer. Patent originator Victor Company of Japan Co., Ltd.

Claims (1)

[Claims] A method for manufacturing an optical information recording medium having a read-only area and a recordable area on the same surface of the optical information recording medium, the method comprising: recording with an organic material on a mirror-polished glass master disk; a step of forming a film to obtain a glass master with a recording film; and focusing a laser beam emitted in a state where the intensity is modulated by an information signal to be recorded on the recording film of the glass master. the step of forming unevenness corresponding to the read-only area and the recordable area; and the step of forming an organic substance only in the recordable area of the unevenness formed on the recording film of the glass master disk. A method for manufacturing an optical information recording medium, characterized by: