JP2002279707A - Manufacturing method for single-sided two layered disk, single-sided disk and recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a single-sided two layered disk (exclusive use for reproduction, or recording, reproduction and erasure type) of a surface covering layer recording type by a simple method. SOLUTION: A reflection film 42 is film-deposited on a grooves and information pits side of a substrate 40 having usual thickness and then a UV resin 43 is applied by spinning. When information is transferred by using a stamper 44 having grooves and pit information, the stamper is made of a transparent acrylic material for UV light 46 and the UV resin 43 is cured by UV light irradiation from the stamper side. The acrylic stamper is previously coated with an inorganic material 45 consisting of a transparent or semitransparent material so that the acrylic stamper 44 and the UV resin are easily pealed after the UV resin is cured. The UV resin 43 and the acrylic stamper 44 are easily pealed by coating the surface of the acrylic stamper 44 with the inorganic material 45.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention comprises a phase change recording layer (or a reflective film and a translucent film) which can be recorded and reproduced by irradiating a laser beam on both sides of an intermediate layer having a thickness of about 30 μm. One phase change layer (or reflection film) is in contact with the disk substrate, and the other phase change recording layer (or translucent film) is a surface recording type in which a 100 μm-thick surface cover layer is provided. Method for producing single-sided double-layer disc (or surface-reproducing type) and 100
From the side of the μ-thick surface cover layer, NA (Numerica)
l Aperture) The laser beam is separately focused on two phase change layers (or a reflective film and a translucent film) with an 0.85 objective lens, and the respective phase change recording layers (or a reflective film and a translucent film) are condensed. ) Relates to a recording / reproducing (or reproducing) apparatus for performing recording / reproducing (or only reproducing).

[0002]

2. Description of the Related Art In recent years, optical disks have attracted attention as large-capacity memories. Optical disks are roughly classified into three types: a read-only type represented by a CD, a one-time write once type represented by a CD-R, and a rewritable type represented by an external memory of a computer.

Further, the rewritable type is roughly classified into a magneto-optical disk and a phase change disk. A phase-change optical disc records information using a recording film that reversibly undergoes a phase change between an amorphous phase and a crystalline phase by irradiating a laser beam. Information is reproduced according to the difference in reflectance. Whether the laser irradiated portion of the recording film becomes amorphous (mark) or crystalline (erased state) depends on whether the irradiated portion exceeds the melting point of the material constituting the film,
Alternatively, since it depends only on the temperature exceeding the crystallization temperature, there is an advantage that overwriting is possible by scanning with the intensity modulation of the laser beam.

In recent years, with the increase in the density of optical discs, there is a tendency of the following technology. Hereinafter, the technology for increasing the density will be described by taking a read-only disc as an example. When the CD disk was commercialized, the wavelength of the semiconductor laser mounted on the optical head was 780 nm, the numerical aperture NA of the objective lens was 0.52, and the thickness of the CD disk was set at 1.2 mm. However, recent D
With the advent of VD discs, these parameters have changed as follows. In a DVD drive, the semiconductor laser wavelength of the optical head is 650 nm, the NA of the objective lens is 0.6, and the substrate thickness of the DVD disk is 0.6 mm.
It is. The reason that these parameters were changed at once at the transition from the CD to the DVD was that there was a limit that further densification would not be possible without changing the existing parameters of the CD disk.

That is, the diameter of the condensed spot of the optical head is
As is generally well known, when the wavelength of the laser is λ and the numerical aperture of the lens is NA, λ /
It is proportional to NA. Therefore, to make the spot diameter smaller, it is customary to make the wavelength shorter and make the NA as large as possible. At this time, assuming that the thickness of the disk substrate is t, care is taken to set a small coma aberration proportional to t (NA) ³ / λ. That is, in order to perform high-density recording, it is sufficient to set the NA to be large and the λ to be short as described above, but on the other hand, coma aberration increases. Therefore, in order to cancel this, the thickness of the substrate through which the laser light is transmitted is reduced.

Recently, various proposals have been made for post DVDs, in which a semiconductor laser has a wavelength of 410 nm and NA is as large as possible, and the substrate thickness on the side where the laser is incident is reduced accordingly. One example is using an optical head with a wavelength of 410 nm and an NA of 0.85,
Recording is performed by irradiating a laser from the side of the cover layer of 0.1 mm. According to a recent announcement, this method uses a track pitch of 0.3 μm and a minimum pit pitch of 0.3 μm.
A capacity of 25 GB per side can be achieved at 19 μm. Here, the substrate thickness is expressed as a cover layer instead of 0.1 mm because a mechanical (physical) rigidity cannot be obtained at 0.1 mm. Since it is not possible to maintain the mechanical rigidity of the disk by using a dummy substrate, a 0.1 mm cover layer on the surface of the dummy substrate is applied or a sheet is attached, High-density recording is achieved by irradiating laser from the side of the cover layer instead of from the substrate side.

On the other hand, as another measure for high density,
The wavelength of the semiconductor laser remains red (wavelength 650 nm)
Attempts have been made to increase only the on-line capacity of recording / reproducing from one side based on the current DVD standardization. Such single-sided, dual-layer DVD-ROM discs have already been commercialized. Normally one layer DVD-RO
Since the single-sided capacity of the M disk is 4.7 GB, the online capacity of the single-sided dual-layer DVD-ROM disk is 9.4 Gbytes.
B, but the online capacity has been slightly reduced in consideration of the crosstalk of the reproduced signals from each surface.
The total of the layers is 8.5 GB.

Further, ISOM '98 (International S
ymposium on Optical Memory 1998 October 20-22), Th-N
-05 `` Rewritable Dual Layer Phase-Change Optical Dis
k)), a phase-change double-layer disc (hereinafter simply referred to as a single-sided dual-layer RAM disk) capable of recording and reproducing from one side by laser irradiation as described below has also been proposed. .

FIG. 17 shows one side 2 described in the above article.
2 shows the configuration of a layer RAM disk. As a rough structure, the first layer of RAM is formed on a polycarbonate (PC) substrate.
And a second layer of RAM provided on a separate PC board, which is laminated with a UV curable resin film having a thickness of 40 μm. The first layer has a structure of PC substrate side of the ZnS-SiO ₂ protective film / GeSbTe recording layer / ZnS-SiO ₂ protective film. The second layer is composed of A from the side of the UV cured film.
and it has a film structure of u interference film / ZnS-SiO ₂ protective film / GeSbTe recording layer / ZnS-SiO ₂ protective film / Al-Cr reflective film.

The laser light condensed by the objective lens is switched by a servo circuit between a case where the first layer recording film is focused and a case where the second layer recording film is focused. To perform recording and playback. Originally, if the recording capacity of each layer is set to 4.7 GB / side where normalization is performed, the total of the two sides is 9.4 GB per side, but the crossing due to optical interference between the first layer and the second layer. In consideration of the talk, the recording capacity of each layer is reduced to 4.25 GB by slightly lowering the recording density.
The total of the layers is 8.5 GB.

As described above, regarding the method for increasing the capacity of an optical disk, a method using a blue laser, a high NA objective lens and a thin cover layer of 0.1 mm, and a substrate thickness and a laser wavelength different from those of the current DVD disk are used. Same, 2 on one side
Attempts have been made to increase the online capacity from one side only about twice as a layer.

[0012]

The above two methods have the following disadvantages. That is, in the case of high-density recording with a blue laser, a high NA lens, and a 0.1 mm thick cover layer, the mechanical accuracy of a 130 mm diameter disk cannot be maintained with a 0.1 mm thick substrate. A dummy substrate is needed to maintain it. On the dummy substrate, pits or grooves of a predetermined preformat are formed, and 0.1 mm above the pits or grooves is formed thereon.
Overcoat a thick surface cover layer. Therefore, in this method, a single-sided dual-layer disc is difficult.

On the other hand, although the online capacity of a dual-layer RAM disk can be approximately doubled,
Because it uses the same technology, it is not high density recording than DVD.

The demand for higher density requires a 25 GB single-sided capacity for next-generation discs as a means for storing information corresponding to future high-definition images. Further, there is a demand for a disk having a capacity of 50 GB which is twice that of the above. Therefore, an attempt has been made to produce a single-sided double-layer disc even for the surface recording which is said to be difficult to form a double-layer.

Generally, a single-sided, double-layer disc for surface recording is
It has been proposed to make it by the following method. FIG. 18 shows the structure of a single-sided, double-layer disc for surface recording. In the following, for simplicity, a case of a read-only type in which two layers are a translucent film and a reflective film from the side of the surface cover layer will be described for the moment.

1 is a surface cover layer having a thickness a of 70 μm, 2 is an intermediate transparent layer separating the translucent film 6 and the reflection film 5 and has a thickness b of 30 μm. NA (Num) of the objective lens 7
erical aperture) is 0.85, and the semiconductor laser light 8
Is approximately 410 nm (blue). When the thicknesses of the surface cover layer 1 and the intermediate transparent layer 2 are added, a + b = 70 + 30
Becomes 100 μm. That is, when the blue laser is focused on the reflection film at the back of the two-layer disc, the distance from the surface is 100 μm.
m.

The semi-transparent film 6 reflects the blue laser when it is focused on the translucent film and reproduces the signal, and transmits when the blue laser is focused on the deep reflective film and transmits the signal. The information is reproduced by reflecting from the reflective film on the side. Reference numeral 4 denotes a disk substrate. The thickness c of the substrate may be any thickness as long as it is necessary to maintain the mechanical accuracy of the two-layer disk. In general, it may be 1.2 mm which is the same as that of a CD, but the thickness of a + b is 100 μm (=
0.1 mm) may be subtracted, and it may be 1.1 mm, or 1.5 mm or 2 mm if the mechanical accuracy is further improved.

A single-sided surface recording type 2 having the structure shown in FIG.
An example of manufacturing a layer disc will be described below. The disk substrate 4 having groove and pit information on one side is a normal CD or DVD.
It can be manufactured by the same molding technology as described above. On the other hand, it is necessary to form grooves and pit information also in the intermediate transparent layer 2 having a thickness of 30 μm.
After forming the groove and pit information of the substrate 4 by molding (injection), the A is set in a vacuum device such as a sputtering device.
When reflection in 1 or AlCr alloy or blue is considered, a reflective film 5 of Ag or the like is formed. Normally, a reflection film 5 is formed on these grooves and pits, and 2P (Pho
Spin-to-Polimarization type photo-curable resin 30
Then, a stamper made of Ni or the like in which another groove or pit is formed is pressed from the surface side to transfer information to the resin. However, in general, in order to cure the photocurable resin while transferring it, UV (ultraviolet) or the like must be applied from the substrate 4 side, but as described above, the pit information side of the substrate 4 Since the reflection film 5 is already formed, the UV light does not reach the resin. In addition, since UV light is not transmitted through the pressed Ni stamper side, a method of curing the resin with UV light transmitted through the gap between the resin from the edge of the disk (around the disk) is adopted as a measure to reduce the thickness. However, as a matter of course, there is a problem that the curing is incomplete. When the curing of the resin is completed,
Similarly, a semi-transparent film 6 made of Au or Ag is formed by a vacuum device such as a sputtering device, and a UV-cured resin 70 μm is spin-coated thereon, and UV (ultraviolet) is applied from above.
To form a surface layer, thereby completing a surface recording type single-sided dual-layer disc. In addition, the above-mentioned 2P for better transfer of pits and grooves to the intermediate layer in a single-sided dual-layer disc is preferred.
Type photo-curable resin materials are disclosed in
This is described in Japanese Patent Publication No. 345073. However, this publication does not disclose a specific method for producing a single-sided dual-layer disc.

As a method for avoiding the disadvantage that the UV layer is not completely cured, a surface cover 1 made of a resin having a thickness of 70 μm is formed in the same manner as forming grooves and pit information on a substrate by molding. At the time, a Ni stamper having groove and pit information is pressed and irradiated with UV light from the side opposite to the stamper to be cured, and after forming a translucent film of Au or Ag on this thin substrate having a thickness of 0.1 mm by sputtering. The substrate and the thin substrate having a thickness of 0.1 mm may be bonded with a UV-curable resin having a thickness of 30 μm. In this case, Au or A
g is irradiated with UV light from the side of the translucent film,
0-60% light is transmitted (because it is translucent)
It is possible to cure the resin. However, the method of bonding the thin substrate and the normal substrate has the following disadvantages. That is, when a translucent film of Au or Ag is formed on a thin substrate (actually, a thin film) having a thickness of 0.1 mm by a vacuum apparatus such as sputtering, heat generated during sputtering is used.
The thin substrate (film) is thermally deformed and becomes useless before bonding.

Accordingly, an object of the present invention is to improve the uncured problem of the UV curable resin during the light irradiation process in the above-described 2P process, and to produce a single-sided double-layer disc by a simple method.

[0021]

According to the present invention, a reflective film of Al or an Al alloy or Ag is formed on a side of a substrate having a normal thickness where grooves or information pits are formed, and then a film having a thickness of 30 μm is formed. When the UV resin is spin-coated and the information is transferred by a stamper having groove and pit information, the stamper is made of an acrylic material transparent to UV light, and the UV resin is irradiated with UV light from the stamper side to cure the UV resin. Further, after the UV resin is cured, the acrylic stamper side is previously coated with an inorganic material made of a transparent material or a translucent material so that the acrylic resin and the UV resin are easily peeled off. Normal,
The organic UV resin and the organic acrylic stamper are extremely difficult to peel off when the UV resin is cured. However, if the acrylic stamper according to the present invention is coated with an inorganic material, it can be peeled off without any problem.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings.

First, as a first embodiment of the present invention,
0.1 mm thick surface cover layer single sided dual layer disc, especially 2
A manufacturing process of a two-layer disc in which both layers are exclusively used for reproduction will be described with reference to FIGS.

FIG. 1 shows a state in which a reflective film 42 is formed on a normal molded substrate 40 by using a vacuum sputtering apparatus (not shown). In the figure, 41 is formed by molding,
It represents a group groove / information pit on the substrate surface. As a material of the reflection film, an Al-based alloy such as Al or AlCr is usually used in the case of a red laser. When a blue laser for higher density recording is used, usually, an alloy material such as Ag or AgPtCu is used to improve the adhesion to the substrate.
The thickness of the reflection film is usually about 100 nm to 300 nm in order to reflect the laser light by 99% or more.

Next, as shown in FIG. 2, a UV resin 43 as a UV-curable polymer was uniformly applied to a thickness of 32 μm. The spin coating conditions of the UV resin 43 are variously combined depending on the viscosity of the resin.
450 using UV resin with PS (centipoise) viscosity
When the coating was performed while rotating at 0 rpm, a UV resin layer was formed with a thickness of approximately 32 μm. Incidentally, the thickness of the UV resin layer as the intermediate layer is preferably 25 to 35 μm.

On the other hand, as shown in FIG. 3, a transparent stamper 44 is prepared in advance for a blue laser made of an acrylic material, and is placed on grooves / information pits formed on the surface thereof by a vacuum sputtering apparatus. S which is also transparent to blue laser
An iO ₂ dielectric film 45 was formed to a thickness of 100 nm. This SiO
_{(2) The} dielectric film 45 is formed in advance so that the acrylic stamper 44 and the UV layer 43 are easily peeled off when the UV resin is cured later. Any material may be used as long as it is easily peelable. For example, a mixed film of Si or ZnS and SiO ₂ ,
TiO ₂ or the like is preferable.

The method for producing the acrylic stamper may be the same as that for forming an ordinary optical disk. A replica of acrylic may be produced using a Ni-plated stamper produced by a mastering process as a master. In this case, since it is not used as an optical disc, its thickness may be any thickness as long as it is necessary as a stamper in the 2P process. However, when an organic material such as acrylic is used as a stamper, the thickness of the stamper must be at least as large as that of a normal optical disc in order to transfer grooves / pits while maintaining a certain degree of rigidity. In the example, an acrylic stamper was manufactured with a thickness of 2 mm.

Next, as shown in FIG. 4, an acrylic stamper 4 having a SiO ₂ dielectric film 45 formed on the surface of the groove / pit is formed.
4 is a 32 μm thick UV resin layer 4 previously applied
The UV light 46 was irradiated from the side of the stamper 44 while pressing the sample 3. The pressing of the stamper 44 was carefully set so that the grooves / pits could be accurately transferred and the thickness of the UV resin intermediate layer 43 was about 30 μm. In addition, the UV light to be irradiated is a mercury lamp with an intensity of about 800 W at 20 W.
Irradiated for seconds. It has been confirmed in a previous experiment that the UV resin causes a photopolymerization reaction at this intensity and is completely cured.

In this state, when the acrylic stamper 44 is slowly peeled off from the UV resin intermediate layer 43, the SiO ₂ dielectric film 45 which has been formed on the acrylic stamper side until now is removed.
However, when the UV resin intermediate layer 43 is cured, the UV resin intermediate layer 43 adheres to the UV resin intermediate layer side 43 and is separated from the acrylic stamper. As a result, the grooves / pits 47 of the acrylic stamper and the SiO ₂ dielectric film 45 are transferred to the UV resin intermediate layer 43 as shown in FIG.

In this state, as shown in FIG.
Using a vacuum sputtering apparatus, _TwoOn the dielectric film 45
Next, a translucent film 48 made of Au or Ag is formed. Half
The material of the transparent film 48 is usually Au for a red laser.
Ag is used for the blue laser. And its thickness
Is generally 50% reflection and 50% transmission.
Therefore, it is usually set to about 8 to 12 nm.

Next, as shown in FIG. 7, a UV resin is spin-coated on the semi-transparent film 48 and irradiated with UV light.
The surface cover layer 49 was formed to a thickness of 70 μm. The viscosity of the UV resin used at this time is 800 CPS (centipoise), and the rotation speed of the coating is 4000 rpm.
The UV light intensity was 800 W, which was the same as when the intermediate layer was formed, but the curing time was 40 seconds. The thickness of the surface cover layer is preferably 65 to 75 μm, and the total thickness of the intermediate layer and the surface cover layer is preferably 90 to 110 μm.
μm.

It has been confirmed that a single-sided, single-sided, read-only disc for surface recording with a thickness of 0.1 mm can be manufactured by the processes shown in FIGS. 1 to 7 described above.

In the above embodiment, SiO ₂ is used as a release material between the acrylic stamper and the cured UV resin.
Although an example in which an Au translucent film was formed on SiO ₂ after peeling was shown, Au was used as a peeling material instead of SiO ₂ , and after peeling, this Au film was left as it was on the side close to the surface. It can be used as a translucent film for reproduction. However, in the case of Au, if the peeling is unsuccessful and unevenness occurs, it cannot be used as a translucent film, and the translucent film cannot be repaired.

Next, as a second embodiment of the present invention, a process for manufacturing a single-sided, double-layer disc having a recording / reproducing surface recording layer will be described.

FIG. 8 shows the configuration of a phase change type single-sided dual-layer disk of a surface recording type. In the same manner as in the case of reproduction only, a plurality of thin films such as a reflection film are originally formed on the substrate 30 or the intermediate layer 25.
8 are stacked with irregularities along the shapes of the grooves / pits 50 and 51 formed on the surface of FIG. 8, but for simplicity of explanation, FIG.
22, 23, 24) and (26, 27, 28, 29).

In FIG. 8, reference numeral 30 denotes a disk substrate produced by the same molding as a normal optical disk, and a groove / information pit 50 is formed on the surface thereof. As in the case of reproduction only, the thickness of the disk substrate 30 may be any thickness as long as the mechanical strength can be maintained. On the surface of the disk substrate on which the grooves / information pits 50 are formed, a phase change recording medium capable of recording / reproduction / erasing is formed. 2
Reference numeral 6 denotes a dielectric protection film made of a ZnS / SiO ₂ mixed film, and 27 denotes a phase change recording film made of a GeSbte ternary alloy. Further, a ZnS.SiO ₂ dielectric protection film 28,
The AgPtCu reflection film 29 is formed in this order.

In the same manner as in the case of a read-only disc,
The intermediate layer 25 is adhered, and a groove / information pit 51 is formed on one side (closer to the surface) of the intermediate layer 25. On this groove / pit surface, a phase-change medium capable of recording and reproducing is also formed. That is, 21 is a ZnS.SiO ₂ dielectric protective film, 22 is a phase change recording film made of a GeSbTe ternary alloy, 23 is a ZnS.SiO ₂ dielectric protective film, and a translucent film 24 of Au or the like is laminated thereon. ing. A surface cover layer 20 made of UV resin is formed on the dielectric protection film 21. The thickness of the intermediate layer 25 that optically separates the phase change medium is 30 μm as in the case of the reproduction only. Also, the thickness of the surface cover layer 20 is 70 μm.
m is the same as in the case of reproduction only.

Next, a method of manufacturing this surface recording type single-sided, dual-layer recording / reproducing / erasing optical disk will be described with reference to FIGS.

First, as shown in FIG. 9, a phase change medium 52 is formed on the surface of the grooves / information pits 50 formed on the ordinary molded substrate 30 by using a vacuum sputtering apparatus (not shown). As shown in FIG. 8, the phase change medium 52 is composed of AgP
tCu reflection film 29, ZnS / SiO ₂ dielectric film 28, G
The structure is such that an eSbTe recording film 27 and a ZnS.SiO ₂ dielectric protection film 26 are formed in this order. At this time,
The thickness of each film is optimized as appropriate. However, in the case of a two-layer disc, the medium far from the surface receives only about half of the normal laser beam, and is considered to have high sensitivity. That is, AgP which has an effect as a cooling film simultaneously with the reflection film
The thickness of the tCu film 29 is set from 80 nm to 100 nm, and is not so thick.

The dielectric protection film 28 between the recording film 27 and the reflection film 29 is set to about 30 nm to keep the recording film away from the cooling film (reflection film) 29. If the dielectric protection film 28 is extremely thinner than this, the heating part of the recording film 27 irradiated with the laser beam is rapidly cooled by the reflection film 29 as a cooling film, and the desired phase change characteristic cannot be obtained. That's why. The recording film 27 has a thickness of 20 n
m, the lower dielectric film 26 is the same as that of the conventional phase change optical disk, and is preferably about 180 nm.

Next, as shown in FIG. 10, a UV curable resin 25 was uniformly applied to a thickness of 32 μm. UV resin 2
The spin coating conditions of No. 5 are variously combined depending on the viscosity of the resin. In this embodiment, the UV resin having a viscosity of 400 CPS (centipoise) was applied while rotating at 4500 rpm, and the thickness of the UV resin layer was approximately 32 μm. 25 could be formed.

On the other hand, as shown in FIG. 11, a stamper 44 transparent to a blue laser made of an acrylic material is prepared in advance, and a groove / information pit formed on its surface is
Au which is translucent to blue laser in vacuum sputtering equipment
The film 24 was formed to a thickness of 80 nm. This Au translucent film 24
When the UV resin cures later, the acrylic stamper 44 and U
In order to facilitate the peeling of the V intermediate layer 25, the Au translucent film 24 bonded to the UV intermediate layer side is designed to function as a reflection film of the phase change medium. As is well known, Au is an extremely chemically stable metal,
Difficult to chemically bond with other substances. Therefore, even if Au is formed on the acrylic stamper 44, it hardly adheres. On the other hand, when the UV resin is cured later, the UV resin has a higher activity, so that it can react with Au to some extent and adhere. Not chemically bonded to acrylic and UV
Materials that can be used as a reflection film of the phase change medium (especially a reflection film of a blue laser) after being bonded to the resin layer 25 include:
There is Ag and the like in addition to Au. However, since Ag alone has a problem of rust, an alloy such as AgCu is desired.

The method of manufacturing the acrylic stamper 44 may be the same as that for forming an ordinary optical disk. An acrylic replica may be formed using a Ni-plated stamper manufactured by a mastering process as a master. In this case, since it is not used as an optical disc, its thickness may be any thickness as long as it is necessary as a stamper in the 2P process. However,
When an organic material such as acrylic is used as a stamper, the thickness of the stamper must be at least as large as that of an ordinary optical disc in order to transfer grooves / pits while maintaining a certain degree of rigidity. In the embodiment, the acrylic stamper 4 has a thickness of 2 mm.
4 was produced.

Next, as shown in FIG. 12, an acrylic stamper 44 in which an Au translucent film 24 is formed on the surface of the groove / pit.
Is applied to a 32 μm-thick UV resin layer 25 previously applied.
UV light 46 was irradiated from the side of the stamper 44 while being pressed. When the stamper 44 is pressed, the grooves / pits can be transferred accurately and the thickness of the UV resin intermediate layer 25 is 3
It was carefully set to be about 0 μm. In addition, the UV light 46 to be irradiated was applied slightly longer because the Au film 24 on the surface of the acrylic stamper was translucent. That is, irradiation was performed with a mercury lamp at an intensity of about 800 W for 40 seconds. It has been confirmed in a previous experiment that the UV resin 25 undergoes a photopolymerization reaction at this intensity and is completely cured.

In this state, when the acrylic stamper 44 is slowly peeled off from the UV resin intermediate layer 25, the Au translucent film 24, which has been formed on the acrylic stamper side, becomes
When the UV resin intermediate layer 25 is cured, the UV resin intermediate layer 25 is adhered to the UV resin intermediate layer 25 and peeled off from the acrylic stamper 44. As a result, as shown in FIG. 13, the grooves / pits 51 of the acrylic stamper and the translucent Au film 24 are transferred to the UV resin intermediate layer.

In this state, as shown in FIG. 14, a phase change medium 53 is formed on the Au translucent film 24 by using a vacuum sputtering device (not shown). Since the translucent film has already been formed with Au, the ZnS.SiO ₂ dielectric protection film 23, the GeSbTe phase change recording film 22, and the ZnS.SiO
_Two dielectric protection films 21 were formed in this order. The thickness of each film is considered so that the blue laser light reaches the phase change medium 52 at the back. First, the thickness of the phase change recording film 22 was set to 10 nm so that about 50% of the blue laser was transmitted even after passing through the Au translucent film thereon. In addition, 50%
, The phase change recording film 22 must be made highly sensitive. For this reason, the Au translucent film 2
4 and the phase change recording film 22, the dielectric protection film 23
It was set slightly thicker in nm. The dielectric protection film 21 on the side closer to the lower surface is the same as that of a normal phase-change optical disc.
It may be about 0 nm.

Next, as shown in FIG.
From above, a UV resin was spin-coated and irradiated with UV light to form a surface cover layer 20 with a thickness of 70 μm. The viscosity of the UV resin used at this time is 800 CPS (centipoise), and the rotation speed of the coating is 4000 rpm. The UV light intensity was 800 W, which was the same as when the intermediate layer was formed, but the curing time was 40 seconds.

It was confirmed that a single-sided, double-layer disc capable of recording / reproducing and erasing information on a surface recording layer having a thickness of 0.1 mm can be manufactured by the processes shown in FIGS. 9 to 15 described above.

As described above, in the present invention, an acrylic stamper which is transparent to UV light is used, and an inorganic material which is easy to peel off from the acrylic stamper after the UV resin is cured is formed on the surface thereof in advance. By setting, UV from stamper side
The UV resin can be completely cured by irradiating light, and the UV resin and the stamper can be easily separated after the UV resin is cured. Therefore, it is possible to produce a single-sided, dual-layer (reproduction-only / or recording / reproduction erasing) disk of the recording type using a relatively simple method.

In the second embodiment, as the inorganic material for separating the acrylic stamper and the cured UV stamper,
Although the Au translucent film was used, this was used as a dielectric film such as SiO ₂ as in the first embodiment, and after the stamper and the UV resin intermediate layer / dielectric film were peeled off, Au was used by a sputtering apparatus.
Translucent film, ZnS · SiO ₂ dielectric film, GeSbTe recording film, ZnS · SiO ₂ dielectric film of identical be deposited in this order on the recording and reproducing erasable double layer disk can of course be prepared .

Next, a description will be given of an optical disk apparatus for reproducing data from a read-only optical disk manufactured according to the first embodiment, or performing recording and reproduction using a recording / reproduction optical disk manufactured according to the second embodiment. Figure 1
6 is a block diagram showing a configuration of the optical disk device.

The optical disk 61 is the above-mentioned read-only optical disk or the optical disk for recording and reproduction. Tracks are spirally formed on the surface of the optical disk 61, and the disk 61 is driven to rotate by a spindle motor 63.

Recording and reproduction of information on and from the optical disk 61 are performed by an optical pickup 65. The optical pickup 65 is connected to a sled motor 66 via a gear, and the sled motor 66 is controlled by a sled motor control circuit 68.

A speed detection circuit 69 is connected to the sled motor control circuit 68, and a speed signal of the optical pickup 65 detected by the speed detection circuit 69 is sent to the sled motor control circuit 68. A permanent magnet (not shown) is provided at a fixed portion of the thread motor 66. When the drive coil 67 is excited by the thread motor control circuit 68, the optical pickup 65 moves in the radial direction of the optical disk 61.

The optical pickup 65 is provided with an objective lens 70 supported by a wire or a leaf spring (not shown). The NA of the objective lens 70 is 0.85. The objective lens 70 can be moved in the focusing direction (the direction of the optical axis of the lens) by driving the drive coil 72, and can be moved in the tracking direction (the direction orthogonal to the optical axis of the lens) by driving the drive coil 71. It is.

Laser drive circuit 75 of laser control circuit 73
As a result, a laser beam is emitted from the semiconductor laser oscillator 79. Laser light emitted from the semiconductor laser oscillator 79 is irradiated onto the optical disk 61 via the collimator lens 80, the half prism 81, and the objective lens 70. The reflected light from the optical disk 61 is guided to a photodetector 84 via an objective lens 70, a half prism 81, a condenser lens 82, and a cylindrical lens 83.

The photodetector 84 includes a four-divided photodetector cell 84.
a to 84d. Output signals of the photodetection cells 84a to 84d are supplied to differential amplifiers OP1 and OP2 via current / voltage conversion amplifiers 85a to 85d and adders 86a to 86d.
Supplied to

The differential amplifier OP2 includes adders 86a and 86
A signal related to the focus point is output according to the difference between the two output signals b. This output is output from the focusing control circuit 87.
Supplied to The output signal of the focusing control circuit 87 is supplied to the focusing drive coil 72. As a result, control is performed such that the laser beam is always just focused on the recording film of the optical disk 61. The focusing control circuit 87 switches the focus under the control of the CPU 90 to the reflective film 42 or the translucent film 48 shown in FIG. 7 for a read-only disc, and to the first layer shown in FIG. Switching is performed on the recording film 27 or on the recording film 22 of the second layer.

The differential amplifier OP1 includes adders 86c and 86
A track difference signal corresponding to the difference between the two output signals is output. This output is supplied to the tracking control circuit 88. The tracking control circuit 88 generates a track drive signal according to the track difference signal from the differential amplifier OP1.

The track drive signal output from the tracking control circuit 88 is applied to the drive coil 7 in the tracking direction.
1 is supplied. The track difference signal used in the tracking control circuit 88 is transmitted to the thread motor control circuit 68.
Supplied to

By performing the focusing control and the tracking control, the sum signal of the output signals of the respective photodetection cells 84a to 84d of the photodetector 84, that is, the addition signal for adding both output signals of the adders 86c and 86d. The change in the reflectance from the pits formed on the tracks of the optical disk 61 corresponding to the recorded information is reflected in the output signal of the optical unit 86e. This signal is supplied to the data reproducing circuit 78. The data reproduction circuit 78 reproduces the recorded data based on the reproduction clock signal from the PLL circuit 76.

When the objective lens 70 is controlled by the tracking control circuit 88, the objective lens 70 is
The sled motor 66, that is, the optical pickup 65 is controlled so as to be located near the center position of the inside.

The motor control circuit 64, thread motor control circuit 68, laser control circuit 73, PLL circuit 76, data reproduction circuit 78, focusing control circuit 87, tracking control circuit 88, error correction circuit 62, etc.
9 is controlled by the CPU 90. CPU 90
Controls the recording / reproducing apparatus comprehensively in accordance with an operation command provided from the host device 94 via the interface circuit 93. The CPU 90 also uses the RAM 91 as a work area, and performs a predetermined operation according to a program recorded in the ROM 92.

[0064]

As described above, according to the present invention, it is possible to manufacture a single-sided two-layer (read-only / recording / reproduction / erasing type) disc of a recording type with a front cover layer by a relatively simple method.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first manufacturing process of a read-only dual-layer disc.

FIG. 2 is a sectional view showing a second manufacturing process of a read-only dual-layer disc.

FIG. 3 is a sectional view showing a stamper used in a process for manufacturing a read-only two-layer disc.

FIG. 4 is a sectional view showing a third manufacturing process of the read-only dual-layer disc.

FIG. 5 is a sectional view showing a fourth manufacturing process of the read-only dual-layer disc.

FIG. 6 is a sectional view showing a fifth manufacturing process of the read-only dual-layer disc.

FIG. 7 is a sectional view showing a sixth manufacturing process of the read-only dual-layer disc.

FIG. 8 is a cross-sectional view showing a configuration of a surface recording type phase change type single-sided dual-layer disc.

FIG. 9 is a sectional view showing a first manufacturing process of a single-sided, dual-layer recording / reproducing erasing optical disc.

FIG. 10 is a sectional view showing a second manufacturing process of the single-sided, dual-layer recording / reproducing / erasing optical disk.

FIG. 11 is a cross-sectional view showing a stamper used in a manufacturing process of a single-sided, dual-layer recording / reproducing / erasing optical disk.

FIG. 12 is a cross-sectional view showing a third manufacturing process of the single-sided dual-layer recording / reproducing erasing optical disk.

FIG. 13 is a sectional view showing a fourth manufacturing process of the single-sided, dual-layer recording / reproducing / erasing optical disk.

FIG. 14 is a sectional view showing a fifth manufacturing process of the single-sided, dual-layer recording / reproducing erasing optical disk.

FIG. 15 is a sectional view showing a sixth manufacturing process of the single-sided, dual-layer recording / reproducing / erasing optical disk.

FIG. 16 is a block diagram showing a configuration of an optical disk device that performs reproduction and recording using the optical disk of the present invention.

FIG. 17 is a sectional view showing the configuration of a single-sided dual-layer RAM disk.

FIG. 18 is a cross-sectional view showing the configuration of a single-sided, dual-layer disc for surface recording.

[Explanation of symbols]

1: surface cover layer, 2: intermediate transparent layer, 4, 40: substrate,
5, 42: reflective film, 6: translucent film, 7: objective lens, 8
... Laser light, 41 ... groove / pit, 43 ... UV resin, 44
… Stamper, 45… SO ₂ ,

Claims (20)

[Claims] An optical disc substrate having grooves and information pits on its surface is provided with a reflective film for reflecting laser light, and a semi-transparent film for the laser is formed through the reflective film and an intermediate layer having a predetermined thickness. Provided, and another groove and information pits are also formed on the translucent film surface of the intermediate layer, and further, a surface cover layer is overcoated by a predetermined thickness on the translucent film, A method for producing a surface-reproduced single-sided double-layer disc in which information pits on the substrate or information pits on the intermediate layer are reproduced by focusing laser light on the translucent film or the reflection film, A photo-curable polymer is applied as an intermediate layer on the reflective film provided thereon, and the separate grooves and information pits are formed on the surface, and a transparent stamper that transmits light for curing the polymer is used as the polymer. While pressing against the transparent stamper Irradiating light to cure the polymer, separating the transparent stamper from the cured polymer, and transferring the another groove and information pit to the intermediate layer. A method for producing a single-sided, double-layer disc for reproduction. 2. The transparent stamper according to claim 1, wherein an inorganic thin film for facilitating separation of the polymer from the transparent stamper after photocuring is formed on the surface of the transparent stamper. A method for producing a single-sided, double-layer disc for surface reproduction according to (1). 3. The single-side surface for surface regeneration according to claim 1, wherein the transparent stamper is made of an acrylic material.
How to make a layer disc. 4. The method according to claim 2, wherein the inorganic thin film is made of a dielectric material transparent to UV light. 5. The method according to claim 4, wherein said dielectric material is made of SiO ₂ . 6. The method according to claim 1, wherein the inorganic thin film is made of Au.
After the transparent stamper is peeled off from the polymer and the Au thin film, the Au semi-transparent film is placed on the side close to the surface of the surface-reproduced single-sided two-layer disc. 3. The method for producing a single-sided, double-layer disc for surface reproduction according to claim 2, wherein the disc is used as a translucent reflective film. 7. The single-sided double-layer disc for surface reproduction according to claim 1, wherein the thickness of the intermediate layer is 25 to 35 μm, and the thickness of the surface cover layer is 65 to 75 μm. Method. 8. The method according to claim 1, wherein the total thickness of the intermediate layer and the surface cover layer is set to 90 to 110 μm. 9. A first phase-change medium rewritable by irradiating a laser beam onto an optical disk substrate having grooves and information pits on its surface, and the phase-change medium and an intermediate layer having a predetermined thickness are provided. Providing another phase-change medium that is translucent to the laser through, and another groove and information pits are also formed on the translucent phase-change medium surface of the intermediate layer,
A surface cover layer is overcoated by a predetermined thickness on the surface of the translucent phase change medium, and a laser beam is focused on the translucent phase change medium or the first phase change medium, and A recording / reproducing and erasing single-sided dual-layer disc of a surface recording type in which recording / reproducing / erasing is performed on the first phase change medium and the translucent phase change medium on the intermediate layer, A photocurable polymer is applied as the intermediate layer on the first phase change medium provided, and the other grooves and information pits are formed on the surface, and a transparent stamper that transmits light for curing the polymer is provided. By irradiating the light from the side of the transparent stamper while pressing against the polymer, the polymer is cured, the transparent stamper is peeled off from the cured polymer, and the another groove and the information pit are placed in the middle. Including a step of transferring to a layer The method for producing surface recording erased single-sided dual-layer disc, characterized in Rukoto. 10. The transparent stamper according to claim 1, wherein an inorganic thin film for facilitating separation of the polymer from the transparent stamper after photocuring is formed on the surface of the transparent stamper. A method for producing a single-sided, double-layer disc for surface reproduction according to (1). 11. The method according to claim 9, wherein the transparent stamper is made of an acrylic material. 12. The method according to claim 10, wherein the inorganic thin film is made of a dielectric material transparent to UV light. 13. The method according to claim 12, wherein said dielectric material is made of SiO ₂ . 14. The inorganic thin film is made of Au.
u is set to a thickness that is translucent to the laser,
11. The surface according to claim 10, wherein after removing the transparent stamper from the polymer and the Au thin film, the Au semi-transparent film is used as a semi-transparent reflective film on the side closer to the surface of the surface-reproduced single-sided dual-layer disc. A method for producing a single-sided, double-layer disc for reproduction. 15. The production of a single-sided, double-layer disc for surface reproduction according to claim 9, wherein the thickness of the intermediate layer is 25 to 35 μm, and the thickness of the front cover layer is 65 to 75 μm. Method. 16. The method according to claim 9, wherein a total thickness of the intermediate layer and the surface cover layer is set to 90 to 110 μm. 17. A single-sided, double-layer disc for surface reproduction manufactured according to the method of claim 1. Description: 18. A single-sided, double-layer, surface recording / reproducing erasable disk manufactured according to the method of claim 9. Description: 19. A reproducing apparatus for reproducing information recorded on the single-sided, double-layer disc for surface reproduction according to claim 17. 20. A recording / reproducing apparatus for recording / reproducing information using the surface recording / reproducing and erasing single-sided double-layer disc according to claim 18.