JPH11328738A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in crosstalk mixed in reproduced signals even when the track pitch is decreased, by providing a first guide groove of a recording medium with a second guide groove having a smaller width than the width of the first guide groove. SOLUTION: A second guide groove is formed in the bottom (the part near the surface of a first transparent substrate 101) of a first guide groove 102 having 0.4 μm width. The second guide groove is formed to have 0.2 μm width. A recording layer 104 comprising org dyes is formed on the information recording area where the first guide groove 102 and the second guide groove 103 are formed so that the inside of the first guide groove 102 and the second guide groove 103 are filled with the recording layer 104. The recording layer 104 is covered with a metal or alloy reflection film 105. Then a second transparent substrate 106 as a dummy substrate is laminated with an adhesive layer 106 on the first transparent substrate 101. By this method, information can be recorded with good signal characteristics even when the track pitch is decreased, and for example, about 4.7 GB memory capacity can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical information recording medium on which information can be recorded using a light beam, and more particularly to an optical information recording medium using an organic dye film as a recording film.

[Prior art]

[0002] In recent years, large-capacity, high-density optical information recording media have been put to practical use. Read-only media include compact discs (CD: Compact Disc) and laser discs (LD: La
serDisc) is widely used. Also, C
The spread of D-ROMs (Compact Disc-Read Only Memory) and video CDs to the market is rapidly spreading.

[0003] Further, as a rewritable medium, a phase-change disc (PD),
2. Description of the Related Art A magneto-optical disk (MO: Magnet Optical Disc) or the like has been put to practical use as a medium for a computer external storage device. In addition, a write-once CD (CD) that can be recorded only once and can be reproduced by a CD and a CD-ROM drive
-R: Compact Disc-Recordable) is being established as a prototype disc, a master disc, and a medium for an external storage device of a computer at the authoring stage.

Under such circumstances, an optical disk including music data such as a CD, high-quality moving image data such as an LD, and computer data such as a CD-ROM has been proposed as a next-generation multimedia medium. Was done. This optical disc was standardized as a DVD (Digital Versatile Disc) in December 1995.

[0005] A typical DVD disk structure will be briefly described with reference to the drawings. FIG. 3 shows a conventional DV.
FIG. 4 is a diagram illustrating a medium section of D. In the figure, 301 is the first
, 302 is a reflective film, 303 is an adhesive layer, 304
Denotes a second transparent substrate, and 305 denotes a pickup. This structure represents the structure of DVD-5 of the DVD standard, and is a single-layer single-sided optical disk. Hereinafter, the first transparent substrate 301 will be described with the surface on the side of the adhesive layer 303 as “back surface” and the surface on the opposite side as “front surface”. The first transparent substrate 301 is a substrate having an information recording area in which pit rows are formed at a track pitch of 0.74 μm on the back surface. The information recording area is covered with the reflective film 302. The pit train is modulated by data to be recorded, and the shortest pit length is 0.4 μm.

[0006] The second transparent substrate 304 is a dummy substrate having no information recording area.
Is bonded to the transparent substrate 301. Adhesive layer 303
Is usually a transparent ultraviolet curable resin layer. DVD-5
The recorded information is reproduced from the front side of the first transparent substrate 301 by the pickup 305. Its storage capacity is 4.7
A moving image having about 7 times the GB and CD and having an image quality equal to or higher than that of the LD can be recorded for about 2 hours.

[0007] Like a CD-R, a write once DVD (DVD-R: Digital Versatile Disk) which can be recorded only once and can be reproduced by a DVD drive.
Recordable). FIG. 4 is a diagram illustrating a cross section of a conventional DVD-R medium. In the figure, 401 is a first transparent substrate, 402 is a recording layer, 403 is a reflective film, 404 is an adhesive layer, 405 is a second transparent substrate, and 406 is a pickup.

Hereinafter, the first transparent substrate 401 will be described with the surface on the adhesive layer 404 side as the “back surface” and the surface on the opposite side as the “front surface”. The first transparent substrate 401 has a guide groove having a width of 0.4 μm on the back surface and a track pitch of 0.8 μm.
Has an information recording area formed by the above. On the information recording area, a recording layer 402 made of an organic dye such as a cyanine dye or an azo dye is formed. The recording layer 402 is covered by the reflection film 403. The pit row recorded in the guide groove is modulated by data to be recorded, and the shortest pit length is 0.44 μm.

The second transparent substrate 405 is a dummy substrate having no information recording area, and the first transparent substrate 405
Of the transparent substrate 401. Adhesive layer 404
Is usually a transparent ultraviolet curable resin layer. DVD-R
The information is recorded and the recorded information is reproduced from the front side of the first transparent substrate 401 by the pickup 406. Its storage capacity is 3.9 GB.

[0010]

As described above, the DVD
-5 has a storage capacity of 4.7 GB, whereas DVD-
R has a small storage capacity of 3.9 GB. This is because information is recorded on the DVD-R by the first transparent substrate 40.
1 (guide groove) and the recording layer 402 are deformed to form pits.

An organic dye-based recording layer 4 such as a DVD-R
In the optical information recording medium using No. 02, the heat of the irradiated recording laser beam is absorbed by the recording layer 402, and as a result, the recording layer 402 and the first transparent substrate 401 (guide groove) are melted and deformed. This forms pits. The pits are also formed by deforming adjacent land portions (regions between the guide grooves and the adjacent guide grooves). When the track pitch is reduced, when information formed in the adjacent guide groove is reproduced, the deformation of the land portion is mixed into the reproduced signal as a crosstalk component, and the quality of the reproduced signal is reduced.

Therefore, in order to prevent the crosstalk component from being mixed, the track pitch of the DVD-R is set to 0.8 μm.
The track pitch is wider than 0.74 μm for a read-only DVD-5 or the like.

[0013] In general, a read-only DVD-
The pit train such as 5 is recorded by a Kr ion laser having a wavelength of 350 nm. On the other hand, the recording of the pit train on the DVD-R is performed by a semiconductor laser having a wavelength of 635 to 650 nm. The light beam having a longer wavelength has a larger beam diameter narrowed down to the diffraction limit. Therefore, DVD-R
Is set to be longer than the shortest pit length (0.4 μm) of DVD-5 or the like.

From the above factors, the storage capacity of the DVD-R (3.9 GB) is equal to the storage capacity of the DVD-5 (4.7 GB).
However, there is a problem that the DVD-R cannot be used as an authoring medium such as a DVD-5 because it must be smaller than GB). That is, even if the user wants to edit the material of the information recorded on the DVD-5 or the like and use the DVD-R as the medium for the master disk, the storage capacity is insufficient. There has been a problem that information cannot be recorded and cannot be used.

[0015]

According to a first aspect of the present invention, there is provided a substrate having a first guide groove formed on one side, and a cover for covering the first guide groove. An optical information recording medium having the formed organic dye recording film,
The first guide groove includes a second guide groove having a width smaller than the width of the first guide groove.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical information recording medium according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a cross section of an optical information recording medium according to an embodiment of the present invention. In the figure, 101 is a first transparent substrate, 102 is a first guide groove, 103 is a second guide groove, 104 is a recording layer,
105 is a reflection film, 106 is an adhesive layer, and 107 is a second transparent substrate. Hereinafter, the surface of the first transparent substrate 101 on the side of the adhesive layer 106 is referred to as a “back surface”, and the surface on the opposite side is referred to as a “front surface”.

The first transparent substrate 101 is a substrate having an information recording area in which first guide grooves 102 are formed on the back surface at a track pitch of 0.7 μm. The width of the first guide groove 102 is 0.4 μm, and the depth is about 80 nm. First
A second guide groove 103 is formed on the bottom surface of the guide groove 102 (a portion close to the surface of the first transparent substrate 101). The width of the second guide groove 102 is 0.2 μm,
The depth (depth from the bottom surface of the first guide groove 102) is about 5
Any depth in the range of 0-100 nm.

First guide groove 102 and second guide groove 10
A recording layer 104 made of an organic dye such as a cyanine dye or an azo dye is formed on the information recording area in which 3 is formed. The recording layer 104 has a land portion (the region between the first guide grooves 102) having a thickness of 100 to 20.
The first guide groove 102 and the second guide groove 103 are formed to have an arbitrary film thickness within a range of 0 nm, and the inside of the first guide groove 102 and the second guide groove 103 is filled with the recording layer 104.

The recording layer 104 is made of gold (Au), silver (A
g), and a reflective film 105 made of a metal or alloy such as aluminum (Al). The thickness of the reflective film 105 is 50 to 100 nm. Second transparent substrate 107
Is a dummy substrate having no information recording area, and is bonded to the first transparent substrate 101 via an adhesive layer 106 made of a resin material such as an ultraviolet curable resin or an adhesive sheet.

A semiconductor laser having a wavelength of 635 nm is used for the optical information recording medium of this embodiment having the above-described configuration.
The recording laser power is 9 mW and the linear velocity is 3.5 m / s
At a rotation speed of 4.4, a single frequency signal of 4.4 MHz was recorded. When the recorded signal was reproduced and the C / N was measured, it was 60 dB. The crosstalk was measured from the C / N of the recording signal and the C / N of the land adjacent to the recording signal, and was found to be -35 dB. For comparison, a signal was recorded on the DVD-R having the conventional configuration shown in FIG.
When N was measured, it was 60 dB. However, when the crosstalk amount was measured from the C / N of the recording signal and the C / N of the land adjacent to the recording signal, it was -25 dB. As described above, the optical information recording medium of the present embodiment is a conventional DVD-R
Although the track pitch is narrower at 0.7 μm than that of the DVD-5 or the like, the crosstalk amount can be reduced as compared with the conventional DVD-R.

In order to investigate the pit formation mechanism of the optical information recording medium of this embodiment, the optical information recording medium on which the above-mentioned single-frequency signal of 4.4 MHz is recorded is disassembled, and the portion where the pits are formed is examined with an electron microscope. Observed at the second
Layer 104 and first transparent substrate 10 in guide groove 103 of FIG.
Deformation 1 occurred, and pits were formed. Deformation of the recording layer 104 and the first transparent substrate 101 outside the first guide groove 102, that is, at the land portion, hardly occurred. For this reason, the optical information recording medium of the present embodiment has a small amount of crosstalk even if the track pitch is narrowed.

As described above, according to the optical information recording medium of this embodiment, the track pitch is 0.7 μm and the conventional DVD
Information can be recorded with good signal characteristics even if the width is smaller than -5 and DVD-R. Therefore, even if the shortest pit length is 0.44 μm, which is the same as that of the conventional DVD-R, the track pitch can be 0.7 μm, which is narrower than the track pitch of DVD-5. can do.

Next, a method for manufacturing the optical information recording medium of the present invention will be described. FIG. 2 is a diagram for explaining an embodiment of the method for manufacturing an optical information recording medium according to the present invention. In the figure,
201 is a glass master, 202 is a first photosensitive film, 203 is a second photosensitive film, 204 is an exposed portion, 205 is a concave portion, 206
Denotes a stamper, 207 denotes a first transparent substrate, 208 denotes a first guide groove, 209 denotes a second guide groove, 210 denotes a recording layer, 21
1 is a reflection film, 212 is a second transparent substrate, and 213 is an adhesive layer.

A glass master 201 having a diameter of 200 mm and a thickness of 6 mm, one surface of which is smoothed by a method such as polishing.
Is baked on a hot plate at 120 ° C. for 5 minutes for dehydration. As shown in FIG. 2A, the baked glass master 201 is placed on a spin coater, and a positive photoresist for i-line having a maximum absorption spectrum near 365 nm is applied to the glass master 201.
Spin coating on the smoothed surface of the first photosensitive film 20
Form 2 The thickness of the first photosensitive film 202 is about 50 to
The thickness is adjusted so as to have an arbitrary thickness within a range of 100 nm. Glass master 201 on which first photosensitive film 202 is formed
Is subjected to a baking treatment for 1 minute on a hot plate heated to 90 ° C.

Further, as shown in FIG.
Of the first photosensitive film 202 on the surface of the photosensitive film 202
The wavelength end is on the longer wavelength side than the line-type positive photoresist, that is, a type of g-line positive photoresist in which the maximum value of the absorption spectrum is around 436 nm is spin-coated,
A second photosensitive film 203 is formed. The thickness of the second photosensitive film 203 is adjusted to be 80 nm. The glass master 201 on which the second photosensitive film 203 is formed is baked for 1 minute on a hot plate heated to 90 ° C.

First photosensitive film 202 and second photosensitive film 203
Formed on the glass master 201 has an oscillation wavelength of 351 nm.
And an Ar ion laser having an oscillation wavelength of 457 nm are mounted on a master recording apparatus (not shown) provided with two light sources having different wavelengths. The master recording apparatus is configured to simultaneously oscillate laser light emitted from a Kr ion laser and laser light emitted from an Ar ion laser and to focus on the same optical axis.

Then, the laser light emitted from the Ar ion laser having a long wavelength is focused on the second photosensitive film 203, and the second photosensitive film 203 is exposed so as to be exposed with a width of about 0.4 μm. Has been adjusted. In addition, Kr having a short wavelength
The laser light emitted from the ion laser is applied to the first photosensitive film 2
The focus is on 02, and the first photosensitive film 202 is exposed so as to be exposed to a width of about 0.2 μm.

As shown in FIG. 2C, the second photosensitive film 203 is exposed at a track pitch of 0.7 μm and a width of 0.4 μm by the master recording apparatus having the above-described configuration, and the first photosensitive film 202 is exposed. Track pitch 0.7 μm, width 0.2 μm
Then, an exposure portion 204 corresponding to the first guide groove 102 and the second guide groove 103 shown in FIG. 1 is formed.

Glass master 20 on which exposure section 204 is formed
1 is placed on a developing device, and as shown in FIG. 2D, the exposed portion 204 is removed by a developing solution. The developed glass master 201 is baked for 1 minute on a hot plate heated to 90 ° C.

As described above, the surface of the glass master 201 from which the first photosensitive film 202 and the second photosensitive film 203 have been partially removed by exposure and development is coated with Ni by sputtering.
Alternatively, a conductive film such as Cr is formed. Then, FIG.
As shown in (1), the stamper 206 is manufactured by Ni electroforming.

As shown in FIG. 2F, the stamper 206
Is mounted on an injection molding machine, and a resin such as polycarbonate is molded to produce a first transparent substrate 207 to which the first guide groove 208 and the second guide groove 209 are transferred. FIG.
As shown in (g), the first transparent substrate 207 is placed on a spin coater, and the first transparent substrate 207 is provided with a cyanine on the surface on which the first guide groove 208 and the second guide groove 209 are formed. A recording layer 210 made of an organic dye such as a system dye and an azo dye is formed. The recording layer 210 has a land portion (a region between the first guide grooves 102) having a thickness of 100 to 20.
The first guide groove 208 and the second guide groove 209 are filled with the recording layer 210 so as to have an arbitrary film thickness within a range of 0 nm.

As shown in FIG. 2H, the first transparent substrate 207 on which the recording layer 210 is formed is placed on a sputtering apparatus, and the reflection film 21 made of Au, Ag, Al, or the like is formed.
1 is formed to a thickness of 50 to 100 nm. Then, the first transparent substrate 201 on which the reflective film 211 is formed is bonded to a second transparent substrate 212 which is a dummy substrate via an adhesive layer 213. As the adhesive layer 213, an ultraviolet curable resin can be used. After being filled between two substrates, the adhesive layer 213 is cured by irradiation with ultraviolet light. The optical information recording medium of the present invention can be manufactured by the manufacturing method as described above.

[0033]

According to the optical information recording medium of the present invention, even if the track pitch is narrower than that of the conventional DVD-R, the amount of crosstalk mixed in the reproduced signal does not increase.
An optical information recording medium having a larger storage capacity can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a cross section of an optical information recording medium according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining an embodiment of the method for manufacturing an optical information recording medium of the present invention.

FIG. 3 is a diagram illustrating a cross section of a conventional DVD medium.

FIG. 4 is a diagram illustrating a cross section of a conventional DVD-R medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 1st transparent substrate 102 1st guide groove 103 2nd guide groove 104 Recording layer 105 Reflective film 106 Adhesive layer 107 2nd transparent substrate 201 Glass master 202 First photosensitive film 203 Second photosensitive film 204 Exposure Part 205 concave part 206 stamper 207 first transparent substrate 208 first guide groove 209 second guide groove 210 recording layer 211 reflective film 212 second transparent substrate 213 adhesive layer 301 first transparent substrate 302 reflective film 303 adhesive layer 304 Second transparent substrate 305 Pickup 401 First transparent substrate 402 Recording layer 403 Reflective film 404 Adhesive layer 405 Second transparent substrate 406 Pickup

Claims (1)

[Claims] A substrate having a first guide groove formed on one side thereof;
An optical information recording medium having an organic dye recording film formed so as to cover the first guide groove, wherein the first guide groove has a width smaller than the width of the first guide groove. An optical information recording medium comprising a guide groove.