JPH10283682A - Optical disk and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk and its manufacture provided with at least a first recording surface and a second recording surface on a disk substrate and capable of efficiently peeling the second recording surface from a stamper made of metallic system material in a sticking type optical disk and its manufacture. SOLUTION: The optical disk provided with plural recording surfaces recorded with information is provided with the first recording surface 102 formed on the disk substrate 101 and recording the information, a translucent film layer 103 formed on the first recording surface 102 and reflecting a part of a light beam, a first middle layer 104 formed on the translucent film layer 103 and transmitting the majority of the transmitted light beam through, a second middle layer 105 formed on the first middle layer 104 and transmitting the majority of the light beam through, the second recording surface 106 formed on the second middle layer 106 and recording the information and a reflection layer 107 formed on the second recording layer 106 and reflecting the light beam. Then, adhesive force between the stamper made of the metallic system material for forming the second recording surface and the second middle layer 105 is made smaller than the adhesive force between the translucent film layer 103 and the first middle layer 104.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk having a plurality of recording surfaces on which a plurality of disk substrates are bonded, and a method for manufacturing an optical disk.

[0002]

2. Description of the Related Art In recent years, large-capacity optical disks have been demanded.
In order to improve the recording density, attempts have been made to reduce the size of recording pits. Recently, as a high-density optical disk, a digital versatile disk (DVD: Digita) having a diameter of 120 mm and a recording capacity of several GB or more has been developed.
l Versatile Disk) is under development.

FIG. 5 is a schematic diagram showing a schematic configuration of a conventional high-density optical disk. (A) is a schematic sectional view of DVD-9, (b) is a schematic sectional view of DVD-18.
For high-density optical disks, to improve the recording capacity,
There is a dual layer disc having two recording layers.
As a dual layer disc, a DVD-9 that can be reproduced from only one side as shown in FIG.
As shown in (b), a DVD that can be reproduced from both sides
There are 18. DVD-18 is a two-layer optical disk having a four-sided recording surface on both sides and capable of reading information from both sides.

A configuration of an optical disk for reading information on a two-layer recording surface from one side as shown in FIG. 5 and a method of manufacturing the optical disk will be described. FIG. 6 is a schematic diagram showing a schematic cross section of an optical disc having a two-layer recording surface in a conventional high-density optical disc. As shown in FIG. 6, an optical disk having a two-layer recording surface has a first recording surface 6 on a disk substrate 601.
02, translucent layer 603, transparent layer 604, second recording surface 60
5, a reflective layer 606 and a protective layer 607 are formed. Then, the disc base 601 and the transparent disc base on which the recording surface is not formed are pasted together via the adhesive layer 608 to obtain the above-described DVD-9. Also, by bonding an optical disk having the same configuration as the above-mentioned optical disk, the above-mentioned DVD-18 is obtained.

In FIG. 6, a translucent layer 603 reflects an incident light beam by about 20 to 30% and transmits the remaining light beam. The reflection layer 606 reflects almost all of the light beam transmitted through the translucent layer 603. The transparent layer 604 is used to transmit a light beam.
A material transparent to the wavelength of the light beam is used.

[0006] In the above-mentioned laminated optical disk having a plurality of recording surfaces, the thickness of the transparent layer 604 is set such that the center value is 5%.
It is necessary to keep the accuracy at about 55 ± 4 μm in one rotation of the disk as 5 μm. That is, when the distance between the first recording surface 602 and the second recording surface 605 in the disk is not within a predetermined range, the reproduced signal may be deteriorated due to, for example, an aberration occurring in the laser beam for reading information. Was. In a bonded optical disk such as DVD-9 and DVD-18, since the thickness of one disk substrate 601 is as thin as 0.6 mm, the disk substrate 601 is warped, and even in the 2P (PhotoPolymerization) method or the like, It was difficult to set the thickness of the transparent layer within the above range.

[0007] Therefore, in the bonded optical disk, the transparent layer 604 is required to keep the transparent layer at a predetermined thickness.
Some examples use a sheet (or film) having a uniform thickness. FIG. 7 is a schematic diagram showing a manufacturing process of a bonded optical disk using a conventional sheet. As shown in FIG. 7, a first recording surface 701 is formed on a transparent disk base 702, and a translucent layer 703 is formed on the first recording surface 701. The translucent layer 703 controls the incident light beam by about 20 to 3
It reflects 0% and transmits the remaining light beam. The material of the translucent layer is aluminum, gold, an alloy thereof, silicon nitride, or the like.

The stamper 704 has a second recording surface 70
5 are formed. The stamper 704 is a metal material such as nickel and chromium. Between the disk substrate 702 on which the first recording surface 701 and the translucent layer 703 are formed, and the stamper 704 on which the second recording surface 705 is formed, the transparent substrate is uniform with respect to the wavelength of the light beam and has a uniform thickness. Sheet 706
Place.

The disk base 702 and the stamper 7
After pressure is applied from both sides of the disk substrate 04, ultraviolet light is irradiated from the disk base 702 side by the ultraviolet light source 707. The sheet 706 transfers minute irregularities on the second recording surface 705 by pressure and irradiation with ultraviolet rays, and adheres to the translucent layer 703 of the disk base 702.

Thereafter, the second recording surface 705 of the sheet 706
After exfoliating the and the stamper 704, a reflective layer 708 is formed on the second recording surface 705. By bonding two optical disks produced in the above steps, the first recording surface 7
It is possible to manufacture a bonded optical disc in which the distance between the first recording surface 01 and the second recording surface 705 is uniform.

[Problems to be solved by the invention]

In the manufacturing process of the bonded optical disk using the above-mentioned sheet, the semi-transparent layer formed on the first recording surface is made of a metal material such as aluminum, gold and their alloys or silicon nitride. The stamper on which the second recording surface is formed is a metal material such as nickel or chromium. When forming the second recording surface by injection molding, the sheet has to be peeled off only on the stamper side after being cured and adhered by pressurization and ultraviolet irradiation.

However, since both the translucent layer and the stamper that adhere to the sheet are metallic materials, the adhesive strength of the sheet to the translucent layer and the stamper is substantially equal, and the semi-transparent layer and the stamper are semi-transparent in the step of peeling the sheet from the stamper. There is a drawback that the sheet peels off from the transparent layer or from both the translucent layer and the stamper.

Therefore, when producing a bonded optical disk, there are many defective optical disks, so that it is not possible to stably produce a bonded optical disk, and the production efficiency is reduced.

Accordingly, the present invention provides a bonded optical disk and an optical disk manufacturing method, wherein the disk base has at least a first recording surface and a second recording surface, and the second recording surface can be efficiently peeled off from a metal-based material stamper. An object of the present invention is to provide an optical disk and a method for manufacturing an optical disk.

[0015]

According to the present invention, there is provided an optical disc having a plurality of recording surfaces on which information is recorded and a disc base capable of reproducing information by a light beam. A first recording surface formed on the disc substrate on which information is recorded, a translucent layer formed on the first recording surface to reflect a part of the light beam, and a translucent layer formed on the translucent layer and transmitting most of the light beam A first intermediate layer,
A second intermediate layer formed on the intermediate layer and transmitting most of the light beam, a second recording surface formed on the second intermediate layer on which information is recorded, and reflecting the light beam formed on the second recording surface Wherein the adhesive strength between the translucent layer and the first intermediate layer is greater than the adhesive strength between the metallic material stamper for forming the second recording surface and the second intermediate layer.

Further, in the present invention described in claim 2,
2. The optical disc according to claim 1, wherein the first intermediate layer is at least 20 kg / cm2 and 30 kg / cm2 with respect to the translucent layer.
The material having the following adhesive strength is used, and the second intermediate layer is 0.5 kg / cm 2 or more and 2 kg / cm 2 with respect to the stamper.
It is characterized by using a material having the following adhesive strength.

The present invention according to claim 3 provides the invention according to claim 1.
In the above-described optical disc, at least one of the first intermediate layer and the second intermediate layer is a sheet having a constant thickness.

According to a fourth aspect of the present invention, there is provided an optical disk manufacturing method for manufacturing an optical disk having a plurality of recording surfaces on which information is recorded, and a disk base on which information can be reproduced by a light beam. Forming a first recording surface on which information is recorded on the disk substrate, forming a semi-transparent layer on the first recording surface, and applying a second intermediate material to a metal-based stamper on which the second recording surface is formed. A step of forming a layer, a step of arranging a first intermediate layer transparent to a light beam on the translucent layer, closely adhering the second intermediate layer of the stamper to the first intermediate layer, and curing and bonding the first intermediate layer by pressure. A step of forming a second recording surface on which information is recorded by peeling off the stamper after the intermediate layer is cured and adhered, and a step of forming a reflective film for reflecting a light beam on the second recording surface. I have.

The present invention according to claim 5 provides the invention according to claim 4.
In the optical disc manufacturing method described in the above, the second recording surface is
The step of forming the intermediate layer is characterized by applying an ultraviolet curable resin to the stamper by a spin coating method.

According to the present invention, in an optical disk having a plurality of disk substrates bonded together and having a plurality of recording surfaces, a second intermediate layer is used for a translucent layer of a metal-based material such as aluminum, gold, and an alloy thereof. A first intermediate layer having a strong adhesive force is used, and a second intermediate layer having a weaker adhesive force than the first intermediate layer is used for a stamper made of a metal material such as nickel or chromium. Is stronger than the adhesive force to a metal-based material.
Since the separation can be performed only from the recording surface side, defective products of the optical disc due to the separation of the first recording surface side can be reduced.

Further, according to the present invention, in an optical disc having a plurality of recording surfaces bonded together and having a plurality of recording surfaces, an adhesive sheet having a constant thickness at least between the first recording surface and the second recording surface. Therefore, the thickness between the first recording surface and the second recording surface becomes constant, and the deterioration of the reproduction signal of the optical disk can be reduced.

Further, according to the present invention, when a plurality of disk substrates are bonded to each other to manufacture an optical disk having a plurality of recording surfaces, at least a constant thickness is provided between the first recording surface and the second recording surface. Therefore, an optical disk having a constant thickness between the first recording surface and the second recording surface can be manufactured, and the first recording surface and the second recording surface between the optical disks can be manufactured.
Variation in thickness between the recording surface and the recording surface can be reduced.

According to the present invention, the first recording surface and the second recording surface
In the manufacturing process of forming the recording surface, the first recording surface and the second recording surface are formed on separate substrates, respectively. Optical disk can be manufactured by changing the defective recording surface to another recording surface.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical disk and an optical disk manufacturing method according to the present invention will be described. In the description of the embodiments, a description will be given of a configuration and a manufacturing method of an optical disc in which two recording surfaces are formed on one disc base. FIG.
FIG. 1 is a schematic diagram showing a schematic configuration of an optical disc according to an embodiment of the present invention. In FIG. 1, a transparent disk substrate 101 is shown.
A first recording surface 102 is formed thereon, and a translucent layer 103 is formed on the first recording surface 102. Translucent layer 103
Is one that reflects a part of a light beam and transmits another light beam. The material used for the translucent layer 103 is, for example, aluminum, gold, an alloy thereof, silicon nitride, or the like.

On the translucent layer 103, a first intermediate layer 104
Are formed. The first intermediate layer 104 transmits a light beam, and is pressed or irradiated with ultraviolet rays or the like.
It cures and adheres to the translucent layer 103. The first intermediate layer is, for example, a sheet (film) such as an adhesive sheet, and is adhered and cured by pressure.

The second intermediate layer 105 is provided on the first intermediate layer 104.
To form The second intermediate layer 105 also transmits a light beam, is cured by pressure or irradiation of ultraviolet rays, and adheres to a reflective layer described later. Second intermediate layer 1
As the material 05, a material having a lower adhesive strength to a metal-based material than the first intermediate layer 104 is used. The second intermediate layer is, for example, a liquid material such as an ultraviolet curable resin.

Here, the first intermediate layer 104 is a semi-transparent layer 1
The second intermediate layer 105 is made of a material having an adhesive strength of 20 kg / cm 2 or more and 30 kg / cm 2 or less with respect to the second intermediate layer 105.
Use a material having an adhesive strength of 0.5 kg / cm 2 or more and 2 kg / cm 2 or less with respect to a stamper described later.

Further, the second intermediate layer 105 has a second recording surface 106 formed on the opposite side of the surface which is bonded to the first intermediate layer. The second recording surface 106 is formed by transferring information formed on a stamper described later to the second intermediate layer 105.

On the second recording surface 106, a reflective layer 107 having a high reflectivity for reflecting most of the light beam is formed.
The material of the reflective layer 107 is a metal-based material such as aluminum, gold, and alloys thereof.

The disk substrate 101 having the above configuration and a transparent disk substrate (not shown) are bonded together by an adhesive layer 108 using an ultraviolet curable resin or the like, so that a high-density disk having a two-layer recording surface is provided. It becomes an optical disk. Further, by bonding the disk substrate 101 to a disk substrate having the same configuration via the adhesive layer 108, a high-density optical disk having a four-layer recording surface is obtained.

Here, in the configuration of the optical disk of the present invention, at least the disk base 101, the first recording surface 10
2, translucent layer 103, first intermediate layer 104, second intermediate layer 1
05, second recording surface 106, reflective layer 107 and adhesive layer 10
8 as long as the protective layer is provided on the reflective layer 107.

An embodiment of the optical disk manufacturing method of the present invention described above will be specifically described. In the present embodiment, a process of manufacturing a disk substrate having a first recording surface and a second recording surface will be described. In the present embodiment, the second intermediate layer is a transparent layer obtained by curing an ultraviolet curable resin, and the first intermediate layer uses an adhesive sheet.

FIG. 2 is a schematic view showing a manufacturing process of an embodiment of the optical disk manufacturing method according to the present invention. In FIG. 2, a dispenser 203 is provided on the surface of the stamper 202 on which the second recording surface 201 is formed, and on the inner periphery of the stamper 202.
, A predetermined amount of ultraviolet curable resin 204 is dropped in a ring shape.

The stamper 202 is rotated to apply the ultraviolet curable resin 204 to a certain thickness. When the viscosity of the ultraviolet curable resin 204 is 500 CPS, the number of rotations is 2,000 to 3,000.
Rotate between 000 revolutions / min. The thickness of the ultraviolet curable resin 204 can be set according to the viscosity and the number of rotations.

Next, ultraviolet light is irradiated for about 1 second from the ultraviolet light source 205 to cure the ultraviolet curable resin 204, and the second
The second intermediate layer 206 to which the recording surface 201 has been transferred is formed.

Next, on the stamper 202 on which the second intermediate layer 206 is formed, an adhesive sheet of about 45 μm serving as the first intermediate layer 207 is attached. The pressure-sensitive adhesive sheet of the first intermediate layer 207 is bonded by pressure. On the first intermediate layer 207,
The disc substrate 210 having the first recording surface 209 on which the translucent layer 208 is formed is placed. In this state, pressure is applied by a press, and the first intermediate layer 207 is
The first and second intermediate layers 206 and 206 are adhered to each other. For the translucent layer 208, silicon nitride, gold, or an alloy thereof is used.

After pressing, the second intermediate layer 2
The disk substrate 210 is peeled off together with the disc substrate 06. Translucent layer 20
8, the adhesive force of the first intermediate layer 207 to the stamper 20
2, the adhesive force between the first intermediate layer 207 and the second intermediate layer 206 is substantially equal to or greater than the adhesive force of the first intermediate layer 207.
On the second intermediate layer 206, a second recording surface 201 to which information has been transferred from the stamper 202 is formed, and the second recording layer 201 is separated from the stamper 202.

Next, a reflective layer 211 having a high reflectance is formed on the second recording surface 201 by a sputtering method. For the reflective film 211, gold, aluminum, an alloy thereof, or the like is used.

At this point, a first optical disk having the first recording surface 209 and the second recording surface 201 is obtained. The second optical disk can be manufactured by the same manufacturing process as the first optical disk. The first optical disk and the second optical disk are bonded by applying and curing an ultraviolet curing resin between the first optical disk and the second optical disk. Examples of a method of bonding the first optical disk and the second optical disk include a method using an adhesive sheet, a method using a slow-acting ultraviolet curable resin, and a hot-melt type bonding method.

As described above, the first intermediate layer having a higher adhesive force to the metal-based material than the second intermediate layer is used for bonding the translucent layer on the first recording surface and the second intermediate layer, The second intermediate layer, which has a lower adhesive strength to the metal-based material than the layer, is used for transfer from the stamper on which the second recording surface is formed and adhesion to the first intermediate layer. That is, the first intermediate layer has a thickness of 20 kg / cm 2 or more and 30 kg / cm 2 with respect to a translucent film of aluminum, gold, an alloy thereof, or silicon nitride.
It has an adhesive strength of 2 or less. Also, the second intermediate layer is
0.5kg / c for stampers such as nickel and chrome
It has an adhesive strength of not less than m2 and not more than 2 kg / cm2.
The adhesive strength between the first intermediate layer and the second intermediate layer is at least higher than the adhesive strength of the second intermediate layer to the metal-based material. Therefore, in the peeling step, the first intermediate layer is peeled only from the stamper side where the second recording surface is formed without peeling from the translucent film side, and the first recording surface and the second recording surface with few defects are separated. The optical disk provided can be efficiently produced.

Also, since the first recording surface and the second recording surface are bonded after being formed on separate substrates, the inspection of the optical disk can be performed with the first recording surface or the second recording surface formed. Because it can be performed, a defective optical disk can be extracted at an early stage of the manufacturing process, and when either recording surface is defective, a bonded optical disk can be manufactured using another optical disk or a stamper. For,
Defective products of the optical disc after bonding can be reduced.

In this embodiment, since the distance between the recording surfaces can be made precise by using the pressure-sensitive adhesive sheet having a uniform thickness, it is possible to reduce the deterioration of the reproduction characteristics when reproducing the optical disk. . In addition, since it is possible to reduce the variation in the accuracy of the film thickness of the recording surface between the optical disks, it is possible to perform the inspection of the optical disk by sampling without performing the inspection of all the disks, thereby improving the productivity. .

A method for manufacturing a double-sided reproduction optical disk having a four-layer recording surface using the above-described optical disk manufacturing method will be described. FIG. 3 is a schematic view showing steps of a method for manufacturing a double-sided reproduction optical disk having a four-layer recording surface, which is one embodiment of the optical disk of the present invention. In FIG. 3, the first optical disk has a first recording surface and a second recording surface formed on a disk substrate, and the second optical disk has a third recording surface and a fourth recording surface formed on the disk substrate.

In FIG. 3, a predetermined signal is recorded (cut) on a glass master by a cutting machine using a laser as a light source. A stamper is manufactured from the glass master using a plating method. Since four recording surfaces are provided for one disc substrate, four stampers are manufactured.

First, in the first optical disc, the transparent disc base becomes the first disc base on which the first recording surface of the first stamper is transferred at the same time as the formation of the disc base.
On the first recording surface of the first disk substrate, information is recorded by minute irregularities called so-called pits. After molding, a semi-transparent film that is translucent to reproduction light is sputtered on the first recording surface, A first translucent layer is formed. In the second optical disk, a second disk substrate on which the third recording surface and the second translucent layer are formed is obtained by the same process.

Next, a second intermediate layer having a second recording surface is formed on the first optical disk. After uniformly applying the ultraviolet curable resin on the second stamper, the ultraviolet curable resin is cured by irradiating ultraviolet rays, and the information of the second stamper is transferred onto the second intermediate layer to obtain a second recording surface. The thickness of the second intermediate layer on which the second recording surface is formed is 10 μm or less. The 2P method includes a pressurized 2P method and a spin type 2P method.
Either method may be used. In the second optical disk, the fourth recording surface is formed and transferred on the second intermediate layer by the same process.

In the first optical disk, an adhesive sheet as a first intermediate layer is sandwiched between the second intermediate layer on the second stamper and the first semi-transparent layer of the first disk base, and the first optical disk is pressed.
The disk base and the second intermediate layer are bonded. Also in the second optical disk, the second adhesive sheet as the first intermediate layer is sandwiched and pressed between the second disk substrate and the second intermediate layer by the same process, and the second disk substrate and the second intermediate layer are bonded. I do.

In the first optical disk, after the first disk base and the second intermediate layer are sufficiently bonded by the adhesive sheet, they are peeled off between the second stamper and the second intermediate layer. In the second optical disk, the second disk base and the second intermediate layer are sufficiently adhered to each other by the adhesive sheet as the first intermediate layer, and then peeled off between the fourth stamper and the second intermediate layer.

Here, in the first optical disk, an adhesive sheet (first intermediate layer) bonding the first translucent layer and the first transparent layer (second intermediate layer), and an adhesive sheet and the stamper are bonded. The first transparent layers have different adhesive strengths, i.e., the first intermediate layer has a
It has an adhesive strength of 0 kg / cm 2 or more and 30 kg / cm 2 or less, and the second intermediate layer is 0.5 kg / c to the stamper.
It has an adhesive strength of not less than m2 and not more than 2 kg / cm2, and the adhesive strength between the first intermediate layer and the second intermediate layer is at least stronger than the adhesive strength of the second intermediate layer to the metallic material. Only the transparent layer can be peeled off. The same applies to the second optical disc.

That is, when the adhesive force of the adhesive sheet to the first translucent layer is substantially the same as the adhesive force of the first transparent layer to the second stamper, it is attempted to peel only the first transparent layer from the second stamper. The pressure-sensitive adhesive sheet and the first translucent layer may peel off, or the pressure-sensitive adhesive sheet and the first translucent layer and both the first transparent layer and the second stamper may peel off. For example,
When only the pressure-sensitive adhesive sheet is used between the first translucent layer and the second stamper, a release agent or the like must be applied on the second stamper in order to peel only from the second stamper. Disappears.

In this embodiment, since the second intermediate layer is formed on the first disk substrate by using materials having different adhesive strengths for the first translucent layer and the second stamper, the manufacturing process In the above, the second intermediate layer on which the second recording surface is formed can be reliably separated from the second stamper. Also,
In order to form the first recording surface and the second recording surface on the first disk base or the second intermediate layer, respectively,
At the stage where each recording surface is formed, a defective first disk substrate or second intermediate layer on which the recording surface has not been accurately transferred can be found. Furthermore, the first disk base or the second intermediate layer in which a defect has occurred can be replaced with another first disk base or the second intermediate layer and bonded together to manufacture a disk, thereby improving production efficiency.

In the first optical disk, after the stamper is peeled off, a reflection film having a high reflectance with respect to the reproduction light is sputtered on the second recording surface to form a first reflection layer. Second
In the optical disc, the second reflection layer is formed on the fourth recording surface by the same process.

Then, a first optical disk having a first recording surface and a second recording surface and a second optical disk having a third recording surface and a fourth recording surface are placed between the first reflection layer and the second reflection layer. A high-density optical disc having a four-layer recording surface is obtained by applying an ultraviolet curable resin or the like to the adhesive layer and bonding them together with an adhesive layer cured.

As described above, according to the optical disk manufacturing method of the present embodiment, when the second intermediate layer or the second transparent layer is peeled off from the second stamper or the fourth stamper, it can be peeled off accurately. Defective optical discs in the manufacturing process can be reduced.

In the manufacturing process, since the first recording surface is formed on the disk substrate and the second recording surface is formed on the transparent layer, it is possible to find a manufacturing defect with each recording surface formed. Therefore, for example, the first
When the recording surface is formed and the second recording surface is formed on the transparent layer in a defective state, it is possible to find out the defect of the second recording surface before bonding them, and to form another second recording surface. The optical disk can be manufactured by bonding the transparent layer thus formed to the disk substrate on which the first recording surface is formed. That is,
Since the defective recording surface can be found quickly, and the defective recording surface can be changed to another recording surface and bonded to manufacture an optical disk, the production efficiency increases.

Further, since the thickness of the first recording surface and the second recording surface or the thickness of the third recording surface and the fourth recording surface of the optical disk having the four-layer recording surface can be formed uniformly, the variation can be reduced. It is possible to produce an optical disk with less noise.

In the above-described process, of the optical disk having the first recording surface and the second recording surface, a disk substrate having no recording surface formed thereon is bonded to the first reflective layer via an ultraviolet curable resin layer. As a result, a high-density optical disk having a two-layer recording surface is obtained. Further, when the optical disk and the optical disk are bonded together, the optical disks may be bonded to each other using an adhesive sheet instead of the ultraviolet curable resin.

Here, in the 2P method for forming the first and second transparent layers on the second stamper and the fourth stamper, when the spin type 2P method is used, the ultraviolet curable resin can be accurately formed within a thickness of several μm. Can be applied. That is, when a spin coat method is used in applying the photosensitive agent on the master optical disc or forming the recording layer of the write-once optical disc, the photosensitive agent of the master optical disc has a thickness of ± 10 nm with respect to the applied thickness of 110 nm. In the recording layer, the thickness of the recording layer can be controlled with an accuracy of ± 1 nm or less for a coating thickness of 50 to 100 nm.

Therefore, an ultraviolet curable resin is applied to the second stamper and the fourth stamper with a thickness of several μm by a spin coating method, and is irradiated with ultraviolet rays to be cured to form the second stamper.
The first recording layer and the second recording layer or the third recording layer are bonded by bonding the intermediate layer and the second transparent layer to the first disk substrate and the second disk substrate via the first adhesive sheet and the second adhesive sheet. The thickness between the surface and the fourth recording surface can be formed with higher accuracy.

Another embodiment of the method for manufacturing an optical disk according to the present invention will be specifically described. In the present embodiment, steps of a method for manufacturing a disc substrate having a first recording surface and a second recording surface will be described. In this embodiment,
Unlike the first embodiment, the pressure-sensitive adhesive sheet is coated with an ultraviolet-curable resin, and after pressurizing, ultraviolet rays are irradiated to form a first recording surface and a second recording surface.

FIG. 4 is a schematic view showing a manufacturing process of another embodiment of the optical disk manufacturing method of the present invention. In FIG. 4, one surface of an adhesive sheet 401 having a thickness of about 50 μm is coated with an ultraviolet curable resin 402. The coated ultraviolet curable resin 402 is made of an adhesive sheet 401.
It is formed on top with a thickness of several μm.

Next, the adhesive sheet 401 coated with the ultraviolet curable resin 402 is placed on the stamper 404 on which the second recording surface 403 is formed. Further, the disk base 407 on which the translucent layer 405 and the first recording surface 406 are formed is placed on the adhesive sheet 401. Then, pressure is applied by a press from the disk base 407 and the stamper 404 side, and the adhesive sheet 401 is bonded to the disk base 407 and the ultraviolet curable resin 402. In the translucent layer 405,
Silicon nitride or gold and their alloys are used.

After pressing, ultraviolet rays are irradiated from the disk base 407 side by an ultraviolet light source 408 for about 1 second to cure the ultraviolet curing resin 402 coated on the adhesive sheet 401 to form a transparent layer 409. In the transparent layer 409,
The second recording surface 403 of the stamper 404 is transferred. After irradiation with ultraviolet rays, pressure may be applied.

Next, the stamper 404 and the second recording surface 403
Is peeled off from the transparent layer 409 on which is formed.

After the peeling, a reflective layer 410 having a high reflectance is formed on the second recording surface 403 formed on the transparent layer 409 by a sputtering method. For the reflective layer 401, gold or aluminum is used.

At this point, a first optical disk having a first recording surface and a second recording surface is obtained. The second optical disk can be manufactured by the same manufacturing process as the first optical disk. The first optical disk and the second optical disk are bonded together by applying and curing an ultraviolet curing resin between the first optical disk and the second optical disk. Examples of a method of bonding the first optical disk and the second optical disk include a method of bonding an adhesive sheet by applying pressure, a method of using a slow-acting ultraviolet curable resin, and a heat-sensitive bonding method.

By the above manufacturing method, the first recording surface and the second recording surface
A laminated high-density optical disk having a pressure-sensitive adhesive sheet layer and a transparent layer between the recording surface and the optical disk having a thickness of 55 μm ± 10 μm and a rotation of the optical disk within one rotation of 55 ± 4 μm is produced. be able to. Further, after the pressure-sensitive adhesive sheet coated with the ultraviolet curable resin is placed on the stamper and pressurized, it is irradiated with ultraviolet light to form the first recording surface and the second recording surface. After that, the number of steps can be reduced as compared with the manufacturing method in which pressure is applied. In addition, since variations in accuracy among optical disks can be reduced, a large amount of high-density optical disks can be produced. Further, since there is little variation between optical disks, it is possible to inspect the optical disk by sampling, thereby improving productivity.

[0068]

According to the present invention, there is provided a high-density optical disk manufactured by bonding a plurality of optical disks having a plurality of recording surfaces and an optical disk manufacturing method.
The disc substrate has at least a first recording surface and a second recording surface, and the second recording surface can be efficiently peeled off from a metal-based stamper.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an optical disc according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a manufacturing process of an embodiment in an optical disk manufacturing method of the present invention.

FIG. 3 is a schematic diagram showing steps of a method for manufacturing a double-sided reproduction optical disc having four layers of recording surfaces in the optical disc of the present invention.

FIG. 4 is a schematic diagram showing a manufacturing process of another embodiment in the optical disk manufacturing method of the present invention.

FIG. 5 is a schematic diagram showing a schematic configuration of a conventional high-density optical disk. (A) is a schematic sectional view of DVD-9,
(B) is a schematic sectional view of DVD-18.

FIG. 6 is a schematic diagram showing a schematic cross section of an optical disk having a two-layer recording surface in a conventional high-density optical disk.

FIG. 7 is a schematic view showing a manufacturing process of a bonded optical disk using a conventional sheet.

[Explanation of symbols]

 101: Disk base 102: First recording surface 103: Translucent layer 104: First intermediate layer 105: Second intermediate layer 106: Second recording surface 107: Reflection Layer 108 Adhesive layer 201 Second recording surface 202 Stamper 203 Dispenser 204 UV curable resin 205 UV light source 206 Second intermediate layer 207 1st intermediate layer 208 ... translucent layer 209 ... 1st recording surface 210 ... disk base 211 ... reflective layer 401 ... adhesive sheet 402 ... ultraviolet curable resin 403 ... 2nd Recording surface 404 Stamper 405 Translucent layer 406 First recording surface 407 Disk substrate 408 Ultraviolet light source 409 Transparent layer 410 Reflective layer 60 DESCRIPTION OF SYMBOLS 1 ... Disk base 602 ... 1st recording surface 603 ... Translucent layer 604 ... Transparent layer 605 ... 2nd recording surface 606 ... Reflective layer 607 ... Protective layer 608 ... Adhesive layer 701 first recording surface 702 disk base 703 translucent layer 704 stamper 705 second recording surface 706 sheet 707 ultraviolet light source 708 ..Reflective layers

Claims (5)

[Claims] 1. An optical disk having a disk base having a plurality of recording surfaces on which information is recorded and capable of reproducing said information by a light beam, wherein said first optical disk is formed on said disk base and has said information recorded thereon. A recording surface; a translucent layer formed on the first recording surface and reflecting a part of the light beam; a first intermediate layer formed on the translucent layer and transmitting most of the light beam; A second intermediate layer formed on the first intermediate layer and transmitting most of the light beam; a second recording surface formed on the second intermediate layer on which the information is recorded;
A reflective layer formed on a recording surface and reflecting the light beam, wherein the adhesive force between the translucent layer and the first intermediate layer is a metal-based stamper for forming the second recording surface; 2. An optical disc characterized by having an adhesive strength greater than that of the intermediate layer. 2. The optical disk according to claim 1, wherein said first intermediate layer is 20 kg / cm 2 with respect to said translucent layer.
A material having an adhesive strength of not less than 30 kg / cm 2 and not more than 30 kg / cm 2 is used.
An optical disc using a material having an adhesive strength of at least g / cm2 and at most 2 kg / cm2. 3. The optical disk according to claim 1, wherein at least one of said first intermediate layer and said second intermediate layer is a sheet having a constant thickness. 4. An optical disk manufacturing method for manufacturing an optical disk having a disk substrate having a plurality of recording surfaces on which information is recorded and capable of reproducing said information by a light beam, wherein said information is recorded on said disk substrate. First
Forming a recording surface; forming a translucent layer on the first recording surface; forming a second intermediate layer on a metal-based stamper on which a second recording surface is formed; Disposing a first intermediate layer transparent to the light beam on the transparent layer, closely adhering the second intermediate layer of the stamper to the first intermediate layer, and curing the first intermediate layer by applying pressure; and curing the first intermediate layer. Forming a second recording surface on which the information is recorded by peeling off the stamper after bonding; and forming a reflective film for reflecting a light beam on the second recording surface. Optical disc manufacturing method. 5. The method of manufacturing an optical disk according to claim 4, wherein the step of forming the second recording surface on the second intermediate layer includes applying an ultraviolet curable resin to the stamper by spin coating. Optical disc manufacturing method.