JPH0827985B2 - Optical information recording medium and its recording method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical information recording medium for irradiating a laser beam and reproducing recorded data by the reflected light thereof, and a recording method thereof.

[Prior Art] A so-called writable optical information recording medium capable of recording data by irradiation with laser light is Te, B
It has a recording layer composed of a metal layer such as i and Mn and a dye layer such as cyanine, merocyanine, and phthalocyanine, and is capable of being deformed, sublimated, evaporated, or modified by irradiation with laser light. , Pits are formed and data is recorded. In an optical information recording medium having this recording layer, a void is generally provided behind the recording layer in order to facilitate deformation, sublimation, evaporation or modification of the recording layer when forming pits. . Specifically, for example, a laminated structure, which is a so-called air sandwich structure, in which two substrates are laminated with a space therebetween is used.

In this optical information recording medium, the translucent substrate 1 is used.
Laser light is irradiated from the side to form pits. And
When the recorded data is reproduced, the substrate 1 side is irradiated with a laser beam having a power weaker than that at the time of recording, and a signal is read due to a difference in reflected light between the pit and other portions.

On the other hand, a so-called ROM type optical information recording medium in which data is recorded in advance and the data cannot be written or erased thereafter has already been widely put to practical use in the information processing and audio departments. This kind of optical information recording medium does not have a recording layer as described above, and prepits and pregrooves for reproducing recorded data are formed in advance on a polycarbonate substrate by means of pressing or the like, A light-reflecting layer made of a metal film of Au, Ag, Cu, Al or the like is formed and further covered with a protective layer.

The most typical of these ROM type optical information recording media is a compact disc, a so-called CD, which has been widely put into practical use in the audio sector and the information processing sector. The specifications of the recording and reproducing signals of this CD are the so-called CD format. A playback device that has been standardized as, and is compliant with this, is extremely widespread as a compact disc player (CD player).

[Problems to be Solved by the Invention] The above writable optical information recording medium is
It is strongly desired that it be compatible with already widely used CDs and that it can be played back as it is on a CD player.

However, the former writable optical information recording medium has a recording layer not present in CD, and means for forming pits on this recording layer, not on the substrate, is used for recording. Furthermore, since the recording layer has a void layer for facilitating the formation of pits, the reproduced signal naturally differs from that of the CD. For this reason, it is difficult to satisfy the above-mentioned CD format that defines the so-called CD standard.
Therefore, conventionally, it has not been possible to provide a writable optical information recording medium suitable for a CD.

The present invention has been made to solve the above conventional problems, and an object thereof is a writable optical information recording medium and an optical information recording medium capable of obtaining an output signal conforming to the CD format when reproducing data. It is to provide an information recording method suitable for a medium.

[Means for Solving the Problems] That is, in order to achieve the above object, in the present invention, first, in the present invention, melting or decomposition is carried out by irradiation with laser light directly or through another layer on a transparent substrate. Then, in an optical information recording medium having a light absorbing layer forming a pit on the transparent substrate and a light reflecting layer behind which a laser beam is reflected, between the light absorbing layer and the light reflecting layer. , Has a hard layer that is less likely to be thermally deformed than the substrate, and this hard layer has at least one of M100 or more at Rockwell hardness ASTM D785 and 100 ° C. (4.6 kg / cm ² ) or more at heat distortion temperature ASTM D648. Provided is an optical information recording medium having the characteristics of

Furthermore, using this optical information recording medium, a laser beam incident from the side of the substrate is applied to the light absorbing layer to form pits on the transparent substrate, and an optical information recording method is provided. To do.

Secondly, a light absorbing layer that melts and decomposes by irradiation of laser light directly on the transparent substrate or through another layer to form pits on the transparent substrate, and a laser behind it. In an optical information recording medium having a light absorbing layer that reflects light, on the back side where the laser light of the light reflecting layer is incident, a hard layer that is less likely to be thermally deformed than the substrate is provided, and this hard layer is Provided is an optical information recording medium characterized by having at least one of M100 or more in Rockwell hardness ASTM D785 and 100 ° C. (4.6 kg / cm ² ) or more in heat distortion temperature ASTM D648.

Furthermore, using this optical information recording medium, a laser beam incident from the side of the substrate is applied to the light absorbing layer to form pits on the transparent substrate, and an optical information recording method is provided. To do.

[Operation] According to the optical information recording medium and the recording method thereof according to the present invention as described above, when the light absorbing layer is irradiated with laser light, the light absorbing layer absorbs the laser light and melts and decomposes the substrate. A pit is formed on the top. In this case, since there is a hard layer on the back side of the light absorption layer that has higher hardness and is less likely to be thermally deformed than the substrate, laser light is incident on the change for forming such pits. It is more likely to occur on the board side. Therefore, clear pits are formed on the substrate.

The pits thus formed are similar (optical) to the pits previously formed on the surface of the substrate by means such as pressing.
Is what you do. Also, a light reflecting layer made of a metal layer can be provided in close contact with the back of the light absorbing layer. Therefore, an optical information recording medium similar in form to a CD can be obtained, and a recordable optical information recording medium conforming to the CD format can be easily obtained.

[Embodiment] Next, an embodiment of the present invention will be described in detail with reference to the drawings.

An example of a schematic structure of the optical information recording medium according to the present invention,
It is shown in FIGS. In the figure, 1 and 1 are substrates having a light-transmitting property, and 2 is a light absorption layer formed thereon,
This layer has a function of absorbing the irradiated laser beam, melting and decomposing it, and forming a pit on the surface of the light absorbing layer 2 or the substrate 1. Further, 3 is a light reflection layer formed thereon, 4
Indicates a protective layer provided on the outside thereof.

The embodiment shown in FIGS. 1 to 3 is a case where the hard layer 6 is interposed between the light absorption layer 2 and the light reflection layer 3. The embodiment shown in FIGS. 4 and 5 is a case where the hard layer 6 is arranged behind the light absorption layer 3. Further, although not shown, the protective layer 4 can have a function as a hard layer. In any case, the hard layer is formed of a material that is less likely to be thermally deformed than the substrate, and has a Rockwell hardness ASTM D785 of M100 or more and a thermal deformation temperature ASTM D648.
At least 100 ° C. (4.6 kg / cm ² ) or more, it is necessary to have at least one of the characteristics.

2 and 4 show the state before recording with laser light,
3 and 5 show a state after recording, that is, when the recording laser beam from the optical pickup 8 is irradiated, the light absorption layer 2 is melted and decomposed, and the substrate 1 is softened. 1
The state in which the decomposition component of the light absorption layer 2 diffuses into the inside and the optical characteristics of the part change and the part is deformed into a convex shape to form the pit 5 is schematically shown.

FIG. 6 shows that since the pits 5 are formed along the pre-group 9 which is the tracking display means formed on the surface of the transparent substrate 1, the EFM signal is transmitted to the light absorption layer 2 along the pre-group 9. After irradiating the modulated laser spot, the protective layer 4 and the light reflecting layer 3 are peeled from the transparent substrate 1, and the light absorbing layer 2 is removed from the surface of the substrate 1 schematically. There is.

Further, FIG. 7 shows an example of observing the state of the surface of the transparent substrate 1 along the pregroup 9 by using an STM (Scaning Tunneling Microscope). In the figure, the horizontal axis represents the movement distance of the tip (probe) 10 along the pregroup 9, that is, the tracking direction, and the vertical axis represents the height of the surface of the transparent substrate 1. FIG. 7A shows the case where the pit length is relatively short, 10,000 angstroms, and it can be understood that a convex and clear deformation having a height of about 200 angstroms is formed here. Also,
The figure (b) shows the case where the pit length is relatively long at 40,000 angstroms, and a convex deformation with a height of about 200 angstroms is observed here, but the middle part of this deformation is slightly lower. , You can see that the peak of deformation is divided into two.

A specific example of the layer structure of the optical information recording medium and the recording method thereof will be described below.

(Example 1) 0.8 μm in width and 0.08 μm in depth in the range of diameter 46 to 117 mmφ
A polycarbonate substrate 1 having a thickness of 1.2 mm, an outer diameter of 120 mmφ and an inner diameter of 15 mmφ, in which a spiral pregroup having a pitch of 1.6 m and a pitch of 1.6 μm was formed, was molded by an injection molding method. Rockwell hardness of this polycarbonate substrate 1 ASTM D D785
Was M75 and the heat distortion temperature ASTM D D648 was 132 ° C.

As an organic dye for forming the light absorption layer, 0.65 g of
1,1 'dibutyl 3,3,3', 3 'tetramethyl 4,5,4', 5 'dibenzoindodicarbocyanine perchlorate (manufactured by Nippon Senshoku Co., Ltd., product number NK3219) was used as a diacetone alcohol solvent. It was dissolved in 10 cc, and this was applied onto the surface of the substrate 1 by spin coating to form a light absorption layer 2 having a film thickness of 130 nm.

Next, an Au film having a film thickness of 50 nm is formed on the entire surface of a region of the disk having a diameter of 45 to 118 mmφ by a sputtering method.
The light reflecting layer 3 was formed. Further, an ultraviolet curable resin (TYD102 made by San Nopco) is spin-coated on the light reflection layer 3 and is irradiated with ultraviolet rays to be cured to have a film thickness of 10 μm.
Was formed on the protective layer 4. Rockwell hardness ASTM D785 after hardening of this protective layer 4 is M90, and heat distortion temperature ASTM D648
Was 150 ° C.

The recordable area 7 of the optical disc thus obtained
Then, a semiconductor laser having a wavelength of 780 nm was irradiated at a linear velocity of 1.2 m / sec and a recording power of 6.0 mW to record an EFM signal. When this optical disk was reproduced with a commercially available CD player (Aurex XR-V73, reproduction light wavelength λ = 780 nm), the semiconductor laser reflectance was 72%, I ₁₁ / I _top was 0.65, I ₃ / I _top is 0.3
5, the block error rate BLER was 3.4 × 10 ^-3 .

According to the CD standard, the reflectance is 70% or more, I ₁₁ / I _top is 0.6 or more, I ₃ / I _top is 0.3 to 0.7, and the block error rate BLER is 3 × 10 ^-2 or less. The optical disk according to the standard satisfies this standard.

Further, the protective layer 4 and the light reflecting layer 4 of the optical disc after the recording were peeled off, the light absorbing layer 2 was washed with a solvent, and the peeled surface of the transparent substrate 1 was observed by STM (Scanning Tunneling Microscope). A convex deformation was observed in the pit portion. Furthermore, when the recorded portion and the unrecorded portion of the substrate 1 were measured with a spectrophotometer, a peak other than the resin peak seen in the unrecorded portion was observed in the recorded portion.

Note that this example is an example in which the protective layer 4 is used as a hard layer.

(Example 2) A light absorbing layer 2 was formed in the same manner as above on a polycarbonate substrate (Panlite, manufactured by Teijin Chemical) having the same shape and pregroup as in Example 1 above, and a hard layer was formed thereon. A 50 nm-thickness silicon acrylic layer (KR9706 manufactured by Shin-Etsu Chemical Co., Ltd.) is formed as the layer 6, and a 50 nm-thickness Ag film is formed as the light reflection layer 3 thereon by the vacuum deposition method. The same protective layer 4 as in Example 1 was formed. The Rockwell hardness ASTM D785 of the above substrate was M75, and the heat distortion temperature ASTM D648 was 135 ° C. On the other hand, the Rockwell hardness ASTM D785 of the hard layer 6 was M100, and the heat distortion temperature ASTM D648 was 200 ° C.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the semiconductor laser reflectance was 71%, I ₁₁ / I _top was 0.63, I ₃ / I _top was 0.33,
The block error rate BLER was 3.5 × 10 ^-3 .

Further, in the same manner as in Example 1 above, the surface of the transparent substrate 1 of the optical disc after recording is subjected to STM (Scanning Tunneling Mi
Observation with a croscope) revealed convex deformation in the pits. It was confirmed that the middle part of this deformation was slightly low, and the peak of deformation 6 was divided into two.

(Example 3) Polycarbonate substrate having the same shape and pre-groove as in Example 1 (Mitsubishi Gas Chemical Co., Iupilon)
After forming the light absorption layer 2 on the above in the same manner as above, a 50 nm-thick epoxy resin layer (EP-5900 manufactured by Asahi Denka Kogyo Co., Ltd.) is formed thereon as the hard layer 6 and formed thereon. Light reflection layer 3
As a film, a 50 nm-thickness Au film was formed by the vacuum evaporation method, and the protective layer 4 similar to that of the above-described Example 1 was further formed thereon. The Rockwell hardness ASTM D785 of the above substrate is M75.
And the heat distortion temperature ASTM D648 was 132 ° C. On the other hand, the Rockwell hardness ASTM D785 of the hard layer 6 is M9.
The heat distortion temperature ASTM D648 was 140 ° C.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the reflectance of the semiconductor laser was 72%, I ₁₁ / I _top was 0.62, I ₃ / I _top was 0.32,
The block error rate BLER was 2.4 × 10 ^-3 .

(Example 4) On the polystyrene substrate having the same shape and pre-groove as in Example 1 above, the light absorbing layer 2 was formed in the same manner as above.
After forming, an acrylic resin layer (COPONYL made by Nippon Synthetic Chemical Industry) having a film thickness of 50 nm is formed as a hard layer 6 on this, and an epoxy resin is spin-coated thereon to enhance the binding property. From the above, an Au film having a film thickness of 50 nm was formed as the light reflection layer 3 by a vacuum vapor deposition method, and a protective layer 4 similar to that of the above-described Example 1 was further formed thereon. The Rockwell hardness ASTM D785 of the above substrate is M80, and the heat distortion temperature ASTM D
648 was 89 ° C. On the other hand, the Rockwell hardness ASTM D785 of the hard layer 6 is M100, and the heat distortion temperature ASTM
D648 was 100 ° C.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the reflectance of the semiconductor laser was 72%, I ₁₁ / I _top was 0.62, I ₃ / I _top was 0.31,
The block error rate BLER was 7.0 × 10 ^-3 .

Example 5 On a polyolefin substrate having the same shape and pregroove as in Example 1 above, 1,1′dibutyl 3,3,
Example 3 above using 3 ', 3'tetramethyl 5,5', diethoxyindodicarbocyanine perchlorate
After forming the light absorption layer 2 by the same method as above, a silicon acrylic resin layer (KR9706 manufactured by Shin-Etsu Chemical Co., Ltd.) having a film thickness of 50 nm is formed as the hard layer 6 on this, and the light reflection layer 3 is formed thereon. Then, an Au film having a film thickness of 50 nm was formed by a vacuum vapor deposition method, and an epoxy resin was spin-coated on the Au film to enhance the binding property, and then the same protective layer 4 as in Example 1 was formed. Rockwell hardness ASTM D785 of the above substrate is M7
5, and the heat distortion temperature ASTM D648 was 140 ° C. On the other hand, Rockwell hardness ASTM D785 of the hard layer 6 is M1.
The heat distortion temperature ASTM D648 was 200 ° C.

Data was recorded on this optical disc in the same manner as in Example 1 above, and when this was reproduced, the semiconductor laser reflectance was 74%, I ₁₁ / I _top was 0.61, I ₃ / I _top was 0.33,
The block error rate BLER was 2.3 × 10 ^-3 .

(Example 6) 1,1 'dibutyl 3, 3'on an epoxy resin substrate having the same shape and pre-groove as in Example 1 above,
3'Tetramethyl 5,5 'diethoxyindodicarbocyanine perchlorate was used to form a light absorbing layer 2 in the same manner as in Example 1 above, and a hard layer 6 having a thickness of 50 nm was formed thereon. Silicon resin layer (KR22 manufactured by Shin-Etsu Chemical Co., Ltd.
0) was formed, and an Al film having a film thickness of 50 nm was formed thereon as the light reflection layer 3 by a vacuum vapor deposition method, and a protective layer 4 similar to that of the above-described Example 1 was further formed thereon. The Rockwell hardness ASTM D785 of the above substrate is M90, and the heat distortion temperature A
STMD648 was 135 ° C. On the other hand, the hard layer 6
Rockwell hardness ASTM D785 is M100, heat distortion temperature
ASTM D648 was 180 ° C.

Data was recorded on this optical disc in the same manner as in Example 1 above, and when this was reproduced, the reflectance of the semiconductor laser was 73%, I ₁₁ / I _top was 0.61, I ₃ / I _top was 0.30, and the block error rate was The BLER was 2.0 × 10 ^-3 .

(Example 7) After the light absorption layer 2 was formed in the same manner as above on a polycarbonate substrate (Panlite, manufactured by Teijin Chemical) having the same shape and pre-groove as in Example 1 above, light was applied thereon. A 50 nm-thick Ag film is formed as the reflective layer 3 by a vacuum vapor deposition method, and a 50 nm-thick silicon acrylic layer (KR9706 manufactured by Shin-Etsu Chemical Co., Ltd.) is formed as a hard layer 6 on the Ag film. The same protective layer 4 as in Example 1 was formed. The Rockwell hardness ASTM D785 of the above substrate is M75.
And the heat distortion temperature ASTM D648 was 135 ° C. On the other hand, Rockwell hardness ASTM D785 of the hard layer 6 is M1.
The heat distortion temperature ASTM D648 was 200 ° C.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the semiconductor laser reflectance was 71%, I ₁₁ / I _top was 0.64, I ₃ / I _top was 0.34,
The block error rate BLER was 3.7 × 10 ^-3 .

(Example 8) Polycarbonate substrate having the same shape and pre-groove as in Example 1 (Mitsubishi Gas Chemical Co., Iupilon)
After forming the light absorption layer 2 on the above in the same manner as above, as the light reflection layer 3 thereon, a film having a thickness of 50 nm is formed by a vacuum deposition method.
An Au film is formed, and as a hard layer 6 which also functions as a protective layer, an epoxy resin layer having a film thickness of 50 nm (EP-Asahi Denka Kogyo
5900) formed. The Rockwell hardness of the above substrate
ASTM D785 was M75 and heat distortion temperature ASTM D648 was 135 ° C. On the other hand, the Rockwell hardness of the hard layer 6 is
ASTM D785 is M90, heat distortion temperature ASTM D648 is 140 ° C
Met.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the semiconductor laser reflectance was 72%, I ₁₁ / I _top was 0.63, I ₃ / I _top was 0.33,
The block error rate BLER was 2.7 × 10 ^-3 .

(Example 9) On the polystyrene substrate having the same shape and pre-groove as in Example 1 above, the light absorbing layer 2 was formed in the same manner as above.
After forming the film, an Au film having a film thickness of 50 nm is formed thereon as a light reflecting layer 3 by a vacuum vapor deposition method, and an acrylic resin layer (made by San Nopco) having a film thickness of 50 nm is formed on the hard layer 6 also serving as a protective layer. SN-EX-8296) was formed. The Rockwell hardness ASTM D785 of the above substrate is M80, and the heat distortion temperature AST
MD648 was 89 ° C. On the other hand, the Rockwell hardness ASTM D785 of the hard layer 6 is M100, and the heat distortion temperature AS
TMD648 was 100 ° C.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the reflectance of the semiconductor laser was 72%, I ₁₁ / I _top was 0.63, I ₃ / I _top was 0.32,
The block error rate BLER was 7.1 × 10 ^-3 .

(Example 10) After the light absorption layer 2 was formed in the same manner as above on the polymethylmethacrylate substrate having the same shape and pre-groove as in the above Example 1, the light reflection layer 3 was formed on it as a vacuum. An Au film having a thickness of 50 nm is formed by a vapor deposition method, and an epoxy resin is spin-coated on the Au film to enhance the binding property.
A nm polyester resin layer (Econol manufactured by Sumitomo Chemical Co., Ltd.) was formed. The Rockwell hardness of the above substrate AS
TMD785 was M100 and heat distortion temperature ASTMD648 was 110 ° C. On the other hand, the Rockwell hardness of the hard layer 6 is
ASTMD785 is M110, heat distortion temperature ASTMD648 is 115 ℃
Met.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the reflectance of the semiconductor laser was 72%, I ₁₁ / I _top was 0.65, I ₃ / I _top was 0.34,
The block error rate BLER was 8.3 × 10 ^-3 .

Example 11 On a polyolefin substrate having the same shape and pregroove as in Example 1 above, 1,1 ′ dibutyl 3,3,
3 ', 3'Tetramethyl 5,5' diethoxyindodicarbocyanine perchlorate was used to form a light absorbing layer 2 in the same manner as in Example 1 above, and then a light reflecting layer 3 was formed thereon. A 50 nm-thickness Au film is formed by a vacuum evaporation method, and then an epoxy resin is spin-coated thereon to enhance the binding property. Then, a hard layer 6 also serving as a protective layer is formed as a 50 nm-thickness silicon acrylic resin. Layer (Shin-Etsu Chemical KR
9706) was formed. The Rockwell hardness of the above substrate
ASTM D785 was M75 and heat distortion temperature ASTM D748 was 140 ° C. On the other hand, the Rockwell hardness of the hard layer 6 is
ASTMD785 is M100, heat distortion temperature ASTMD648 is 200 ℃
Met.

Data was recorded on this optical disc in the same manner as in Example 1 above, and when this was reproduced, the semiconductor laser reflectance was 71%, I ₁₁ / I _top was 0.62, I ₃ / I _top was 0.34,
The block error rate BLER was 2.4 × 10 ^-3 .

(Example 12) 1,1'dibutyl 3,3 on an epoxy resin substrate having the same shape and pre-groove as in Example 1 above,
3 ', 3'Tetramethyl 5,5' diethoxyindodicarbocyanine perchlorate was used to form a light absorbing layer 2 in the same manner as in Example 1 above, and then a light reflecting layer 3 was formed thereon. An Al film with a thickness of 50 nm is formed by the vacuum deposition method, and a hard layer 6 also serving as a protective layer is formed on the Al film with a thickness of 50 nm
A silicon resin layer (KR220 manufactured by Shin-Etsu Chemical Co., Ltd.) was formed. The Rockwell hardness ASTM D785 of the above substrate was M90, and the heat distortion temperature ASTM D648 was 135 ° C. On the other hand, the Rockwell hardness ASTM D785 of the hard layer 6 was M100, and the heat distortion temperature ASTM D648 was 180 ° C.

Data was recorded on this optical disk in the same manner as in Example 1 above, and when this was reproduced, the reflectance of the semiconductor laser was 72%, I ₁₁ / I _top was 0.62, I ₃ / I _top was 0.32,
The block error rate BLER was 2.1 × 10 ^-3 .

(Comparative Example) In the above example, the Rockwell hardness ASTMD785 after curing of the protective layer 4 formed of the UV curable resin (SN-EX-7052 manufactured by San Nopco) was set to M60, heat distortion temperature ASTMD.
An optical disk was produced in the same manner as in the example except that the temperature of 648 was 4.6 kg / cm ² , and the temperature was 90 ° C.

A wavelength of 780n was recorded on this optical disk in the same manner as in the above embodiment.
When a semiconductor laser of m was irradiated at a linear velocity of 1.2 m / sec and an EFM signal was recorded, a sufficiently clear pit could not be confirmed on the plate surface side of the substrate 1. Then, when this optical disk was reproduced by the same CD player as used in Example 1, the reflectance of the optical disk was 71%, I ₁₁ / I _top was 0.7, and I ₃ /
I _top was 0.37, but block error rate BLER was 1.
There was 5 × 10 ^-1, and the above-mentioned CD standard could not be satisfied.

[Effects of the Invention] As described above, according to the optical information recording medium and the recording method thereof of the present invention, it is possible to form concave pits that are optically similar to CDs by irradiation of laser light and to form the light absorption layer. Since a light reflecting layer can be adhered to the back, a layer structure similar to CD can be obtained. This allows the CD
There is an effect that a recordable optical information recording medium conforming to the format can be easily obtained.

[Brief description of drawings]

1 is a schematic perspective view showing an example of the structure of an optical information recording medium, FIG. 2 is an enlarged sectional view taken along the tracking direction before optical recording in FIG. 1, and FIG. FIG. 4 is an enlarged sectional view taken along the tracking direction after optical recording in FIG. 4, FIG. 4 is an enlarged sectional view taken along the tracking direction of an optical information recording medium showing another embodiment, and FIG. FIG. 6 is an enlarged cross-sectional view taken along the tracking direction, FIG. 6 is an enlarged perspective view of an essential part showing the surface of the transparent substrate of the optical information recording medium after recording, and FIG. (Scann
ig Tunneling Microscope) is an example of a graph showing the relationship between the moving distance along the tracking direction of the chip and the altitude when observed with an ig Tunneling Microscope. 1 ... Substrate, 2 ... Light absorbing layer, 3 ... Light reflecting layer, 4 ...
Protective layer, 6 ... Hard layer

Claims (4)

[Claims] 1. A light absorbing layer which is melted and decomposed by irradiation of laser light on the transparent substrate directly or through another layer to form pits on the transparent substrate, and a light absorbing layer behind the light absorbing layer. In an optical information recording medium having a light-reflecting layer that reflects laser light, between the light-absorbing layer and the light-reflecting layer, a hard layer that is less likely to be thermally deformed than the substrate is provided, and the hard layer is , Rockwell hardness ASTM D785 M100 or more, heat distortion temperature AS
An optical information recording medium having a characteristic of at least one of 100 ° C. (4.6 kg / cm ² ) or more in TMD648. 2. A light absorbing layer which is melted and decomposed by irradiation of laser light on the transparent substrate directly or through another layer to form pits on the transparent substrate, and behind the light absorbing layer. In an optical information recording medium having a light-reflecting layer that reflects laser light, on the back side of the light-reflecting layer on which laser light is incident, a hard layer that is less likely to be thermally deformed than the substrate is provided, and this hard layer is , An optical information recording medium having at least one of M100 or more in Rockwell hardness ASTM D785 and 100 ° C. (4.6 kg / cm ² ) or more in heat distortion temperature ASTM D648. 3. A laser which is incident from the substrate side, using an optical information recording medium having a light absorbing layer which is dissolved and decomposed by irradiation of laser light directly or through another layer on a transparent substrate. In the optical information recording method of irradiating the light absorbing layer with light to form pits on the translucent substrate, the rear side of the light reflecting layer on which the laser light is incident causes thermal deformation compared with the substrate. An optical information recording medium having a hard layer which is difficult to be used, and the hard layer has at least one of characteristics of M100 or more at Rockwell hardness ASTM D785 and 100 ° C (4.6 kg / cm ² ) or more at heat distortion temperature ASTM D648. An optical information recording method comprising: irradiating the light absorption layer with laser light incident from the substrate side to form pits on the translucent substrate. 4. A laser which is incident from the side of the substrate using an optical information recording medium having a light absorbing layer which is melted and decomposed by irradiation of laser light directly or through another layer on the transparent substrate. In the optical information recording method of irradiating the light absorbing layer with light to form pits on the translucent substrate, the rear side of the light reflecting layer on which the laser light is incident causes thermal deformation compared with the substrate. An optical information recording medium having a hard layer which is difficult to be used, and the hard layer has at least one of characteristics of M100 or more at Rockwell hardness ASTM D785 and 100 ° C (4.6 kg / cm ² ) or more at heat distortion temperature ASTM D648. An optical information recording method comprising: irradiating the light absorption layer with laser light incident from the substrate side to form pits on the translucent substrate.