JPH05198000A - Optical recording medium and optical recording method - Google Patents

Abstract

PURPOSE:To provide the optical recording medium which has a high sensitivity and high reflectivity, is high in contrast and is reloadable (in compliance with the formats for CDs and LDs) and the optical recording method. CONSTITUTION:The recording layer 3 of the optical recording medium constituted by providing the recording layer 3 which generates a phase sepn. by irradiation with an energy beam of light, etc., in the multilayered films provided on a substrate 1 is constituted of a material consisting of a compsn. of a spinodal decomposition region. The multilayered films are so constituted that the recording layer heated after the end of the irradiation of the recording layer 3 with the energy is rapidly cooled. Such optical recording medium is used and information is written on the recording layer where the phase sepn. by the spinodal decomposition is generated by irradiating the recording layer with the energy beam of such intensity at which the phase sepn. arises according to the information to be written. The recording layer where the phase sepn. by the spinodal decomposition is generated is irradiated with the energy of such intensity at which the phase sepn. by the spinodal decomposition does not arise, by which the information written therein is read out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a recording layer whose optical properties are changed by means of light, heat or the like on a substrate, and recording, reproduction or erasing of information by utilizing the change of the optical properties. Regarding an optical recording medium to be performed, in particular, an optical recording medium utilizing a phenomenon of phase separation in which an initial phase of a material system is separated into two phases having different compositions by a thermal process meeting respective conditions, and the same Optical recording method.

[0002]

2. Description of the Related Art First, the technical flow of conventional optical recording will be briefly described. First, the theory of reading was established, and along with that, CD and LD, which are read-only memory disks using light diffraction, were developed. After that, an optical recording system was developed in which the user side could write only once. This is called a WO (Write Once) type, and as a typical method, a punching method, a bubble method, etc. have been proposed. After that, as a rewritable type recording method, a magneto-optical method and a phase transition method were developed, and the practical use and improvement thereof are still under study. The advantages and disadvantages of these optical recording technologies will be described below.

[Punching Method] It has the advantages that it can be easily realized by using an appropriate material and has a large contrast. However, if the shapes of the holes are not uniform, S / N deterioration will occur. Therefore, it is necessary to select a material capable of forming uniform holes, and in the case of LD, the structure must be an air sandwich structure. However, there is a problem that special technology is required for manufacturing. Regarding the stability, of course, there is no problem of deterioration of the opened hole, but the stability of the film itself becomes a problem. That is, since it is not possible to secure stability by itself as a single material, it is often the case that various materials are mixed or used as an alloy.
Although e is often used, even if it is a mixture or alloyed, there is a problem that the tendency to oxidize cannot be stopped in a long time and the life is short. In addition, there is a problem that the manufacturing method is complicated and lot-to-lot variation is large. And, of course, this perforation method cannot be rewritten.

[Bubble Method] In this bubble method, an alloy such as NiTi is plastically deformed by the pressure of gas generated from the plastic material on the substrate side by the heat of laser irradiation to form bubbles. Stability is a problem. Also, this bubble method cannot be rewritten as a matter of course.

[Phase Transition System] This phase transition system generally utilizes the phase transition between amorphous and crystalline.
Although the S / N is not deteriorated due to the swelling of the holes as compared with the drilling method, the magnitude of the contrast due to the phase transition is not as large as that of the drilling and it is difficult to secure the S / N.
Further, the stability of amorphous, which is a metastable state, becomes a problem. Furthermore, the constituent material is mainly chalcogenide (Te, Se, etc.), and there is a problem in the stability of the material itself. In addition, some materials take a long time to crystallize, which may deteriorate the performance of the system. However, there are materials that can be rewritten between amorphous and crystalline, and compared with the magneto-optical method described below, there is a great merit that overwriting can be performed with one beam, and it is attracting attention as a promising rewriting method in the future.

[Opto-Magnetic Method] This magneto-optical method is a method in which a change in the Kerr rotation angle is detected and used as a signal. But,
Usually, it is difficult to secure S / N because the rotation angle is small, and various measures have been taken in the medium configuration. Further, generally, Tb or Fe is contained as a metal, and the material composition is easily oxidized, which also complicates the composition of the medium and makes the manufacturing method difficult. However, because it is rewritable, many manufacturers are working on research into stability and S / N improvement.

In response to the above method, we have disclosed in Japanese Patent Laid-Open No.
In Japanese Patent Publication No. 96,389, an optical recording system utilizing phase separation was proposed. According to it, when a large laser power is irradiated, a quenching effect is caused, spinodal decomposition is caused, an LH (Low to High) mode is realized, and irradiation of a small laser power causes phase separation by nucleation and growth. To realize the HL (High to Low) mode. Moreover, due to the difference between the large power and the small power, it is possible to perform rewriting between phase separation due to spinodal decomposition and nucleus generation and growth. The merit of the recording method using this phase separation is that, firstly, the material is mainly an oxide polycrystal, the possibility of structural change, aging such as oxidation, etc. is small, and it is excellent in long-term storage stability. Yes, secondly, the reaction rate is very fast, and thirdly
In addition, the oxide material has a large light transmittance in the visible and infrared regions, has a high degree of freedom in optical design and thermal design when optimizing the optical and thermal characteristics of a multilayer film structure, and also provides a reproduced signal contrast. It is possible to increase.

As described above, many kinds of optical recording methods have been proposed so far, but since CD and LD have been strictly standardized, they are mass-produced as read-only memories at a low cost, and become popular in society. It has penetrated a lot. on the other hand,
The WO and rewritable types have been or are being standardized, but technological innovation is intense and various companies are developing each, and both the drive and the medium are expensive, which affects the CD. , Has not spread much in comparison with LD. The various recording methods thus developed are not necessarily compatible with each other, and are currently achieved by different production processes and different drives. That is, a drive between different recording methods,
The compatibility between the disc and the production process is very poor, so it is costly for both users and suppliers, and
It was inconvenient to use and was one of the causes of delaying the spread.

In the flow of this technique, as one of means for eliminating these adverse effects, a technique in which the format is the same as the CD and LD and WO or rewritable is studied, and some of them are commercialized. Some have been made.
However, originally, it is necessary to set the reflectivity to at least 70% or more, but when the initial reflectivity is set to 70% or more, the absorptivity becomes 30% at the maximum, and the sensitivity is largely deteriorated. There is.
That is, the initial reflectance is 7 for the CD format.
By setting it to 0% or more, WO can be realized. However, since the medium sensitivity itself is set to be large, the medium stability must be sacrificed to a large extent, and when applied to an LD, the linear velocity reaches at least 10 to 20 times that of a CD, so that the writing is performed. A larger laser power is required, and therefore, the absorptance must be set to be large at the expense of the reflectance, which is out of the standard, and the compatibility with the LD player is impaired. As described above, when the WO is realized in the CD or LD format, there is a big problem that the medium design becomes difficult in terms of reflectance and sensitivity.

[0010]

Therefore, as a result of trying the application of the phase separation optical recording system to the CD and LD formats, the present inventors have found that they have high sensitivity, high reflectance and high contrast. Found a method that complies with the standard of
The present invention has been reached. Therefore, an object of the present invention is to provide a writable optical recording medium (which conforms to the CD and LD formats) and an optical recording method which have high sensitivity, high reflectance and high contrast. It is another object of the present invention to provide an optical recording medium and an optical recording method that can reduce the loss due to the reflection of the energy beam during writing as much as possible and can more effectively use the energy of the energy beam.

[0011]

That is, according to the present invention, there is provided an optical recording medium comprising: a multilayer film provided on a substrate; and a recording layer provided with a recording layer which causes phase separation upon irradiation with an energy beam such as light. The recording layer is made of a material having a composition of a spinodal decomposition region, and (b) the irradiated recording layer is rapidly cooled after the irradiation of the energy beam of the light or the like to the recording layer of the multilayer film is completed. The optical recording medium is configured as described above. Further, the present invention provides an optical recording method for writing and reading information to and from a recording layer in a multilayer film provided on a substrate by an energy beam such as light, in which (a) the recording layer is formed from a composition of a spinodal decomposition region. And (b) the multilayer film is configured such that the irradiated recording layer is rapidly cooled after the irradiation of the energy beam of the light or the like onto the recording layer is completed.
(C) An energy beam such as light having an intensity that causes phase separation by spinodal decomposition is irradiated according to the information to be written in the recording layer in which phase separation by spinodal decomposition does not occur, and (d) this written information. Is an optical recording method for irradiating and reading an energy beam such as light having an intensity that does not cause phase separation due to the spinodal decomposition.

That is, according to the present invention, (a) the recording layer is made of a material having the composition of the spinodal decomposition region, and the initial reflectance of this recording layer is a relatively low value, that is, 30% or less, preferably 25%. (B) The specific heat and the thermal conductivity are large so that the recording layer heated by the irradiation of the energy beam is rapidly cooled when the irradiation of the energy beam onto the recording layer is completed. It has a high heat absorption rate, which allows the recording layer to be rapidly cooled after the irradiation of the energy beam, and optical recording with a reflective quenching layer made of a metal such as aluminum or gold in the multilayer film to facilitate the spinodal decomposition. It is a medium.

Further, the optical recording method of the present invention irradiates the recording layer of such an optical recording medium with an energy beam such as light to write information in the recording layer or read information from the recording layer. At the time of writing, (c) the recording layer in which the phase separation due to the spinodal decomposition does not occur is irradiated with an energy beam having an intensity that causes the phase separation due to the spinodal decomposition according to the information to be written, and the reflection of the portion. The value is sufficiently higher than the above-mentioned initial reflectance, that is, 39% or more, preferably 4 or more than the initial reflectance.
Information is written under the condition that the reflectance is as high as about 0% and the reflectance is increased to about 65% or more, preferably about 70 to 80%, and at the time of reading, (d) phase separation due to spinodal decomposition occurs. This is an optical recording method for reading the written information by irradiating the existing recording layer with an energy beam of such an intensity that phase separation due to spinodal decomposition does not occur.

The optical recording medium of the present invention is basically a substrate and a strength that is laminated on the substrate and that causes phase separation by spinodal decomposition depending on the information to be written (that is, a predetermined threshold value or more). When the energy beam has a frequency of 196 KHz, it is composed of a recording layer capable of forming a recording bit having a high reflectance by causing phase separation due to spinodal decomposition by irradiating the energy beam. Has a maximum reflectance of 65% or more, and when the frequency of the energy beam during reading is 720 KHz, the reflectance contrast is within the range of 0.3 to 0.6 times the maximum reflectance, and the initial reflection It is necessary that the index is 0.4 times or less than the maximum reflectivity. Here, as the recording material constituting the recording layer, a recording material having a composition that causes only spinodal decomposition upon irradiation of the recording layer with an energy beam of the threshold value or more, or irradiation with an energy beam of the threshold value or more The spinodal decomposition or the binodal decomposition is caused by, but a composition having a composition that causes the spinodal decomposition by providing a reflective quenching layer described below and irradiating with an energy beam above a threshold value and then quenching is particularly preferable as such a recording material. As a general formula SbOx
(However, x is 0 to 1.0 or 1.5 to 2.3, and preferably 0.3 to 0.6 or 1.8 to 2.1). is there.

In addition to the above antimony oxide-based materials, examples of materials that can be used to form a composition capable of phase separation of the recording material of the recording layer by spinodal decomposition by means of light, heat, etc. include, for example, PbTe-GeTe. Mixed system, A
u-Pt mixed system, Au-Ni mixed system, PbS-PbT
e mixed system, GeSe ₂ -GeSe mixed system, As-Ge-
Alloys such as Te mixed system, Li ₂ O-SiO ₂ mixed system, N
a ₂ O-SiO ₂ mixed system, BaO-SiO ₂ mixed system, A
l ₂ O ₃ -SiO ₂ mixed system, B ₂ O ₃ -SiO ₂ mixed _{system, Li 2 O-B 2 O} 3 mixed _{system, Na 2 O-B 2 O} 3 mixed _{system, K 2 O-B 2 O} 3 mixed _{system, Rb 2 O-B 2 O} 3 mixed _{system, Cs 2 O-B 2 O} 3 mixed system, PbO-B ₂ O ₃ mixture system such as oxides of - or oxide mixture-based material, ZrO ₂ -Th
O ₂ mixed system, CaO-SiO ₂ mixed system, B ₂ O ₃ -Pb
O mixed _{system, B 2 O 3 -V 2 O} 5 mixed system, SnO ₂ -Ti
O ₂ mixed system, NiO-CoO mixed system, Al ₂ O ₃ -Cr
₂ O ₃ mixed system, SiO ₂ -Al ₂ O ₃ mixed system, ZnWO
₄ -MnWO ₄ mixed system, CaWO ₄ -NaSm (WO
_{4) 2} mixed _{system, CaWO 4 -Sm 2 (WO 4} ) 3 mixed system, MnMoO ₄ -ZnMoO ₄ mixed system, Fe ₂ TiO
₄ -Fe ₃ O ₄ mixed _{system, Ca 3 Cr 2 Si 3 O} 12 -Ca
₃ Fe ₂ Si ₃ O ₁₂ mixed system, 65MgSiO ₃ / 35F
eSiO ₃ -CaSiO ₃ mixed system, LiAl ₅ O ₈ -L
NiFe ₅ O ₈ mixture system, NaAlSi ₃ O ₈ -KAlSi
₃ O ₈ mixture _{system, Na 2 O-B 2 O} 3 -SiO 2 mixture system such as oxides - oxide mixture-based material and, LiCl-NaCl mixed system, KCl-NaCl mixed system, CsCl-TlCl mixed system, CaCl _2- MnCl ₂ mixed system, CaCl ₂ -S
rCl ₂ mixed system, LiBr-AgBr mixed system, AgBr
-NaBr mixed system, KBr-NaBr mixed system, TlBr
-CsBr mixed system, KI-NaI mixed system, NaI-Ca
I ₂ mixed system, (GaI ₂ ) ₂ -NaGaI ₄ mixed system,
(GaI ₂ ) ₂ -KGaI ₄ mixed system, (GaI ₂ ) _2-
RbGaI ₄ mixed system, GaAlI ₄ —Ga ₂ I ₄ mixed system and other halide-halide mixed material, CeO
_n system, Bi-Bi ₂ O ₃ mixed system, CaCO ₃ -MnCO
₃ Non-stoichiometric compounds such as oxides and halides of mixed systems, further polymer blends called "polymer alloys" that cause binodal decomposition or spinodal decomposition, and random copolymers that cause microphase separation, Examples include organic materials such as alternating copolymers, block copolymers, graft copolymers, and the like. Then, regarding the composition of such a recording material, a phase diagram of phase separation is drawn according to a conventional method for the selected recording material, and the composition is determined according to the obtained spinodal line.

Further, the medium structure of the optical recording medium of the present invention is preferably a multi-layer film structure in which the recording layer heated at the time of writing is rapidly cooled, for which specific heat and thermal conductivity are high. Aluminum, an aluminum-based metal such as aluminum or Al-Ti, which has a large heat absorption rate and can rapidly cool the recording layer after the irradiation of the energy beam, gold,
It is preferable to provide a reflective quenching layer formed of a material having a high heat absorption coefficient such as copper. This reflective quenching layer is preferably provided on the upper surface side of the recording layer, and has a melting point higher than that of the recording material forming the recording layer and high wettability with respect to the recording material melt. It is formed via an upper surface side dielectric layer made of a protective material selected from a compound.
Further, on the upper surface side and / or the lower surface side of the recording layer, various other materials such as a lower surface side dielectric layer similar to the upper surface side dielectric layer provided on the lower surface side of the recording layer may be provided,
For the purpose of further protecting the surface of the reflective quenching layer, a protective film of, for example, an ultraviolet curable resin, acryl, polycarbonate, epoxy resin or the like may be provided, and on the recording layer for the purpose of increasing the amount of reflected light from the recording layer. It is also possible to provide a high refractive index layer such as ZnS. Specifically, as a preferred example of the medium structure of the optical recording medium of the present invention, the structure of substrate / lower surface side dielectric layer / recording layer / upper surface side dielectric layer / reflection quenching layer / ultraviolet curing resin, substrate / recording Layer / upper surface side dielectric layer / reflection quenching layer / structure of UV curable resin, substrate / lower surface side dielectric layer /
Various materials such as recording layer / reflecting quenching layer / ultraviolet curing resin structure can be used.

In the multilayer film structure thus constructed on the substrate, the initial reflectance of the recording layer should be a relatively low value, that is, 30% or less, preferably 25% or less. It is possible to design a multilayer optical thin film by designing a multilayer optical thin film by using the type of recording material constituting the recording layer and the refractive index and film thickness of each layer constituting the multilayer film as variables.

As a method for producing the optical recording medium of the present invention, a conventionally known method can be adopted, and a recording material is deposited on a substrate to form a recording layer, or
A protective material is applied to form a dielectric layer, and further,
As a means for forming a reflection quenching layer by depositing a material having a high heat absorption rate, for example, a thermal evaporation method, an ion plating method, a reactive sputtering method, a chemical vapor deposition method (CVD), an ion assisting method. A vapor deposition method (IAD), a molecular beam epitaxy method (MBE), etc., a method in which a copolymer or the like is directly subjected to a polymerization reaction on a substrate to deposit, or a secondary compound in which the copolymer or the like is dissolved is appropriately used as a substrate. Examples thereof include a method of coating and depositing on the surface.

Further, as an optical recording method using such an optical recording medium, at the time of writing, phase separation due to spinodal decomposition occurs in the recording layer in which phase separation due to spinodal decomposition has not occurred, depending on the information to be written. Information is written by irradiating an energy beam having such an intensity (that is, an intensity equal to or higher than a threshold value). That is, preferably, when the signal level of the information to be written is H (High), H laser power is applied to the recording layer to form a recording bit with high reflectance at that portion, and the signal level of this information is L. When (Low), writing is performed by a method in which no laser power is applied to the recording layer or an L laser power of an intensity (that is, intensity equal to or less than a threshold value) that does not cause phase separation due to spinodal decomposition is applied. .. Further, at the time of reading, the information written is read by irradiating the recording layer in which the phase separation due to the spinodal decomposition has occurred with an energy beam having an intensity that does not cause the phase separation due to the spinodal decomposition.

Here, with respect to the optical recording medium constructed as described above, the intensity of the energy beam which causes phase separation by spinodal decomposition during writing is determined,
Also, to determine the intensity of the energy beam so that phase separation due to spinodal decomposition does not occur during readout,
Although it can be theoretically calculated from the structure of the constructed medium, it is preferable to experimentally obtain a graph showing the relationship between the intensity of the energy beam and the reflectance and contrast. From the graph shown in the figure, the intensity of the energy beam required for writing, that is, the reflectance can be increased by 39% or more, preferably 45% or more from the initial reflectance to obtain sufficient contrast, and the reflectance is about 65% or more. The intensity of the energy beam is set to be the value of, and the intensity of the energy beam required for reading is set by selecting an appropriate value from the range in which the initial reflectance does not change even if the energy beam is irradiated. It is desirable to do. By setting the intensity of the energy beam required for these writing and the intensity of the energy beam required for reading from the graph showing the relationship between the intensity of the energy beam thus obtained experimentally and the reflectance and contrast, It is possible to ensure the reliable operation of the designed medium.

The optical recording medium according to the present invention is a CD
Alternatively, since it is a medium such as an LD, it is naturally desirable to add a function as a ROM, for example, various indexes or fixed information. There are two possible means. That is, the first is that the ROM information is provided as pre-pits on the substrate in advance separately from the data writing area, and that portion is collectively exposed by the batch exposure device or the multi-track writing device to cause spinodal decomposition. The optical power causes phase separation due to spinodal decomposition to increase the reflectance of this portion, and the reflectance is preferably set to 65% or more or 75% or more which is the standard of CD or LD. Of course, ROM information is provided as pre-pits on the substrate in a mixed manner in the data writing area, and that portion is continuously irradiated with laser with a laser power that causes spinodal decomposition in advance, and phase separation by spinodal decomposition is performed. It may be caused to increase the reflectance of this portion, preferably set to 70 or 75% or more of the reflectance of the CD or LD standard, and the ROM information may be mixed in the data area.

[0022]

EXAMPLES The present invention will be specifically described below based on Examples and Comparative Examples.

Example 1 Using antimony oxide as a recording material, a medium disk having a structure as shown in FIG. 1 was formed. That is, in this medium disk, a SiO ₂ film is deposited on a substrate 1 made of PMMC (or PC) by sputtering to form a lower surface side dielectric layer 2 having a thickness of 1,000 Å. Layer 2
A recording layer 3 having a thickness of 300Å is formed on the upper surface by high-frequency ion plating, and SiO is sputtered on the recording layer 3.
₂ is deposited to form an upper surface side dielectric layer 4 having a thickness of 1,000 Å, and an aluminum (Al) film having a thickness of 500 Å is deposited on the upper surface side dielectric layer 4 as a quenching reflection layer 5. Then, the ultraviolet protection resin 6 is laminated on the quenching reflection layer 5.

Here, the deposition of the recording layer 3 by the above-mentioned high frequency ion plating is carried out by using the ion plating apparatus shown in FIG. That is, Ar gas and O ₂ are introduced into the chamber 9 equipped with the RF power source 7 and the matching box 8 from the gas inlet 10, and RF power of several tens to several hundreds W is applied to the RF coil 11 to generate plasma. Is generated, and Sb is used as an electron beam (E
It is carried out by evaporating and ionizing according to B) and depositing antimony oxide on the rotating substrate 1. Reference numeral 12 is a motor, and reference numeral 13
Is the exhaust port. The film forming parameters at this time mainly include RF power, Ar gas pressure, and O ₂ gas pressure. Of these, Ar gas pressure and O ₂ gas pressure are 6 × 10 ⁻⁴ torr and 3 ×, respectively. The RF power was controlled by setting to 10 ⁻⁴ torr. R in this case
As a result of monitoring Vdc as a measure of the magnitude of F power, the laser power dependence of the recording mode became as shown in FIG. 3 depending on the value of Vdc. Here, the case of HL corresponds to the occurrence of phase separation due to the generation and growth of nuclei, and the case of LH corresponds to the occurrence of phase separation due to spinodal decomposition. As a result, the state diagram as shown in FIG. 3 is estimated. In the state diagram shown in FIG. 3, a region in which only the LH mode occurs was selected as a spinodal region, and a film was formed with the Vdc value.

Information was recorded on the thus prepared medium disk under the conditions of a writing laser power: 16 mW, a reading laser power: 1 mW, a rotation speed: 1,800 rpm, and a recording signal: a standard NTSC signal. When writing was performed on this disk medium, laser power characteristics (characteristics showing changes in reflectance and contrast with respect to laser power) as shown in FIG. 4 were obtained. Reflectance is as
It was about 45% at the depo part, the absorptance was about 40%, and the maximum reflectance by writing was about 75%. Therefore, if the FM-modulated video signal is inverted and written,
It was confirmed that this change in reflectance satisfies the LD standard. Actually, as a result of writing the NTSC signal and measuring the S / N, it was about 48 dB. Further, an environmental test was conducted under the environmental conditions of 50 ° C., 60 ° C. and 70 ° C., 85% RH and 1,000 hours, but there was almost no change in reflectance.
When a medium having such a recording characteristic was reproduced by a commercially available video disc player, it was confirmed that the medium was reproduced in the same manner as a commercially available video disc, and that there was no problem.

FIG. 5 shows a transition model of the information signal, the writing laser power corresponding to the information signal, and the information signal indicating the reproduction signal at this time. From the above results, set the reflectance to 70% or more, which is the standard for CD or LD,
It was found that the spinodal decomposition is used as the principle of increasing the reflectance, and the signal should be inverted before writing. For comparison, FIG. 6 shows a transition model of the information signal in the conventional optical recording medium in which the reflectance of the as depo portion is set to 70%. In this case, the absorptance was about 15%, which required more than twice the laser power as compared with the case of the present invention.

Example 2 A medium manufactured under the same conditions as in Example 1 was used, and a radius of 1 was used.
A reproduction-only area was provided between 50 and 200, and fixed image information was previously provided as prepits in this area. The information is a normal NTSC signal, and the pit shape is the same as that of a normal video disc. As a result of collectively exposing the portion in advance with a xenon flash lamp, the reflectance became about 75% or more. The reflectance complies with the standard, and other parts were masked at that time so that the exposure light was not exposed. As a result, it was found that this disc can be used by being divided into a reproduction-only section and a WO section.

Example 3 A medium prepared under the same conditions as in Example 1 was used, and the entire area was used as a data area. In this, a part of the track was used for reproduction only. As described above, video information was provided, and the portion was written by tracing each track with a laser beam to generate the HL mode and used as a reproduction-only image.

Example 4 In the same manner as in Example 1, antimony oxide was used as a recording material to form a medium disk having the structure shown in FIG. That is, SiO ₂ was deposited on a substrate 1 made of PC by sputtering to form a lower surface side dielectric layer 2 having a thickness of 800 Å, and the lower surface side dielectric layer 2 was used in Example 1 on the lower surface side dielectric layer 2. Same high frequency ion plating as
Ar gas pressure is 6 × 10 ⁻⁴ torr and O ₂ gas pressure is 3 × 1.
RF coil 1 sets RF power of several hundred W by setting to 0 ^-4 torr
1 is applied to generate plasma, Sb is evaporated by an electron beam (EB) to be ionized, and antimony oxide is vapor-deposited on the rotating substrate 1 to form a recording layer 3 having a thickness of about 400 liters. Formed. At this time, a plurality of disks were produced by changing the energy applied to the RF coil, that is, Vdc. SiO ₂ is deposited on the recording layer 3 of each disk thus obtained by sputtering to form an upper surface side dielectric layer 4 having a thickness of 600Å, and the upper surface side dielectric layer 4 is formed on the upper surface side dielectric layer 4. As the quenching reflection layer 5, 600 Å thick aluminum (A
1) A film was deposited, and an ultraviolet protection resin 6 having a thickness of about 2 μm was laminated on the quenched reflection layer 5 to prepare a plurality of optical recording media.

Here, the composition of antimony oxide in the recording layer 3 corresponding to the Vdc value changed during the production of the recording layer 3 was measured by Rutherford Scattering, and the linear velocity was 1 for each optical recording medium. A laser beam of about 12 mW was irradiated at 0.4 m / sec, the phase state of the recording layer 3 after the irradiation was examined, and the relationship between the composition of the recording layer 3 and the phase state was examined. The results are shown in Fig. 7. In FIG. 7, the vertical axis represents the temperature of the recording layer 3, and the horizontal axis represents the oxygen atom number ratio x of SbO _x forming the recording layer 3. In the figure, x is 1.0 to 1.
In the region of No. 5, the recording material of the recording layer 3 produces only binodal decomposition, in the region of x of 0.3 to 0.6 and 1.9 to 2.05, only spinodal decomposition occurs, and x is other than the above. It was found that in the region, either binodal decomposition or spinodal decomposition was generated depending on the cooling conditions after the laser beam irradiation. The region of the recording layer 3 that has undergone spinodal decomposition by irradiation with a laser beam becomes a high reflectance region having a reflectance higher than the initial reflectance, which means that the reflectance of this recording region becomes the LH recording mode. I mean. On the other hand, the region subjected to the binodal decomposition by irradiation with the laser beam becomes a low reflectance region showing a reflectance lower than the initial reflectance, which means that the reflectance of this recording region becomes the HL recording mode. .. In FIG. 7, the solid line 10
1 and the broken line 102 correspond to the state diagram of the recording material and antimony oxide constituting the recording layer 3, the solid line 101 shows the binodal decomposition curve, and the broken line 102 shows the spinodal decomposition curve. In Example 4, x = which causes spinodal decomposition regardless of the cooling conditions of the recording layer.
Antimony oxide having a composition of 2.0 was used as a recording material.

Next, CDWO (Compact Disc Write Onc
The standard of e) is explained. In FIG. 8, the vertical axis represents the reflectance of the recording medium and the horizontal axis represents the recording time.
Is a schematic representation of the standard. C as shown
According to the DWO standard, when laser recording is performed on a recording medium at a frequency of 196 KHz (when 11T signal is applied)
The maximum reflectance R _top of the recording area is 65% or more, 720
When laser recording is performed at a frequency of KHz (when a 3T signal is applied), the reflectance amplitude R ₃ is 0.3 to 0.6 times the maximum reflectance R ₀ , and the initial reflectance R _{0 of the} recording medium. Is 0.4 times or less of the maximum reflectance R _top . This relationship is shown in FIG.
The vertical axis in FIG. 9 represents the reflectance (R ₃ or R _0), the horizontal axis represents the reflectivity R _top, 103 is a straight line R ₃ = 0.6R _top, 104 are R ₃ = 0.3R _top The straight line of 105
Indicates a straight line of R ₀ = 0.4R _top , and it can be seen that the region that satisfies the CDWO standard is in the overlapping portion of the shaded portions in FIG. 9. Specifically R _top = 65
When calculated based on%, R _top ≧ 65%, R ₀ ≦ 26
%, R ₃ ≧ 19.5% is the CDWO standard.

Here, regardless of the cooling conditions, only spinodal decomposition is generated by the irradiation of the laser beam x
An optical recording medium having a recording layer 3 of about 2.0 was used to test whether or not the recording medium complies with the CDWO standard. An actual recording test was performed. That is, the relationship between the values of R _top , R ₃ , and R ₀ of the optical recording medium of x = 2.0 and the laser power was examined. The conditions and results at that time were as follows. [Conditions] Writing laser power: changed by 1 mW in the range of 0 to 15 mW Reading laser power: 1 mW Linear velocity of recording medium: 1.4 m / sec Recording signal: Change at 196 to 720 KHz (duty ratio: 50%) [ Results] FIG. 10 shows the laser power dependence of the reflectance in the recording area. FIG. 11 shows the laser power dependence of the reflectance in the non-recording area. FIG. 12 shows the laser power dependence of the contrast of the reflectance based on the above and. The ratio ( _Rf /) of the reflectance amplitude ( _Rf ) at the recording frequency f and the maximum reflectance ( _Rtop ) in the recording area.
The laser power dependence of R _top ) is shown in FIG. FIG. 14 shows the recording frequency dependence of the reflectance. The recording frequency dependency of the reflectance ratio amplitude at the recording frequency f and (R _f) the maximum reflectance and _{(R top) (R f /} R top) shown in FIG. 15.

As is apparent from FIG. 14, in this optical recording medium, when the writing laser power is 12 mW or more, the maximum reflectance R at the recording frequency of 200 KHz is obtained.
It was found that the _top was 65% or more. In addition, FIG.
From the reflectance amplitude (R
The ratio (R _f / R _top ) of _f ) to the maximum reflectance (R _top ) is 0.31 or more, and the initial reflectance is 26% as is clear from FIGS. 10 and 11. I understand. Furthermore,
From FIG. 15, the ratio (R _f / R) between the reflectance amplitude (R _f ) and the maximum reflectance (R _top ) in the case of the recording frequency of 200 KHz.
It is also clear that the value of _top ) is 0.61 or more. After all, this optical recording medium has R ₀ = 26% and R _top > 65%.
And R _f / R _top > 0.31 are satisfied, and it was confirmed that the CDWO standard was satisfied.

Next, this optical recording medium was put on a commercially available CD-RO.
It was played back with the M drive, but it was played back as it was with a general CD-ROM disc. Also, 50 ℃, 60 ℃, 70
An environmental change test was conducted for 1000 hours at 85% RH at each temperature of ° C, but almost no change in reflectance was observed.

Since this recording medium forms the recording bit as a high reflectance area by spinodal decomposition (the non-recording area is the low reflectance area and the recording area is the high reflectance area), The relationship between the information signal, the writing laser power, and the reproduction signal is as shown in FIG.
As described above, it is necessary to perform writing with a pulse signal in which the respective intensities are proportional to each other. On the other hand, in the conventional writing of gold / organic dye-based CDWO, as shown in FIG. 6, the intensity of the information signal and the writing laser power are pulsed in the opposite pulse.

Example 5 In the optical recording medium of Example 4 above, antimony oxide having a composition of x = 2.0 that causes spinodal decomposition was used as a recording material regardless of the cooling conditions of the recording layer. As shown, x = 0-0.3, 0.6-1.0, 1.5-
In the region of 1.9 and 2.05-2.2, either spinodal decomposition or binodal decomposition is caused by selecting the cooling condition of the recording layer. In order to cause spinodal decomposition in this region, a reflective quenching layer 5 made of a metal such as aluminum is provided near the recording layer 3, and the recording layer 3 is rapidly cooled. Needed and thus reflective layer 5
As a result, even when antimony oxide having the above composition other than x = 2.0 is used as the recording material, the same optical recording medium as in Example 4 can be obtained. Further, aluminum-based metal has a high reflectance of a laser beam and has almost no wavelength dependence of reflectance change (gold used as a reflection layer of conventional gold / organic dye-based CDWO has a short wavelength range, particularly The reflectance rapidly decreases in the vicinity of 500 nm), it can be used for a short-wavelength laser, and it is inexpensive, which is a very preferable material for forming the reflection quenching layer 5.

Example 6 In Example 4, as shown in FIG. 12, a region where the laser power was small, specifically, the laser power was 3 to 5 m.
In the W region, a decrease in reflectance is seen. It is considered that the binodal decomposition occurs in this region and the reflectance is lowered. From this, at least the non-recording area of the optical recording medium is irradiated with low laser power in advance to cause binodal decomposition, thereby lowering the initial reflectance, and then irradiated with higher laser power to decompose spinodal. A recording region having a high reflectance region may be formed to generate a recording region having a higher reflectance contrast.

Example 7 Using an optical recording medium prepared under the same conditions as in Example 4,
A reproduction-only area is provided between a radius of 50 mm and 80 mm,
Fixed information was previously provided as prepits in this area. Further, as a result of collectively exposing the other regions in advance with a xenon flash lamp, the reflectance became about 75%. This reflectance value complies with the CDWO standard. The other parts were masked at the time of collective exposure with this xenon flash lamp. As a result, the optical recording medium of Example 7 could be divided into a read-only area and a WO area and used as a partial ROM.

Example 8 Using an optical recording medium prepared under the same conditions as in Example 4,
Since the entire area is used as a data area and some tracks are used as a read-only area, information is stored in advance as pre-pits on the necessary tracks, and that area is written by tracing the laser beam one track at a time to generate the HL mode. To make it a playback-only area. The optical recording medium of Example 8 could also be used as a partial ROM having a read-only area and a WO area.

[0040]

According to the present invention, it is possible to realize and implement a writable optical recording medium having high sensitivity, high reflectance and high contrast, and recording with a low reflectance set. Since the layer is irradiated with the laser beam for writing, the loss due to the reflection of the laser beam at the time of writing is small and the energy of the laser beam can be efficiently used. Also, by the same process as the ISO standard WO digital data disk, it becomes possible to deposit a recording film or the like on a CD format or LD format substrate and use it as a CD or LD, which has a wide range of applications not available before. Can respond. Further, since this medium can be reproduced by an ordinary video disc player, it can be used as a medium for distributing image information.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of an optical recording medium according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an ion plating apparatus used to deposit a recording layer of Example 1.

FIG. 3 is an explanatory diagram showing laser power dependence of a recording mode in the optical recording medium of Example 1.

FIG. 4 is an explanatory diagram showing laser power dependence of contrast in the optical recording medium of Example 1.

FIG. 5 is an explanatory diagram showing a transition model of an information signal in the optical recording medium of the present invention.

FIG. 6 is an explanatory diagram showing a transition model of an information signal in a conventional optical recording medium.

FIG. 7 is a phase diagram showing the relationship between the composition of antimony oxide and the phase state in the optical recording medium according to Example 4 of the present invention.

FIG. 8 is an explanatory diagram showing a relationship between recording time and reflectance for explaining the CDWO standard.

FIG. 9 is an explanatory diagram showing R _top dependency of reflectance in the optical recording medium of Example 4.

FIG. 10 is an explanatory diagram showing laser power dependence of reflectance of a recording area in the optical recording medium of Example 4.

FIG. 11 is an explanatory diagram showing laser power dependence of reflectance of a non-recording area in the optical recording medium of Example 4.

FIG. 12 is an explanatory diagram showing laser power dependence of reflection contrast in the optical recording medium of Example 4.

FIG. 13 is an explanatory diagram showing laser power dependence of R _f / R _top of a recording area in the optical recording medium of Example 4.

FIG. 14 is an explanatory diagram showing the frequency dependence of reflectance in the optical recording medium of Example 4.

FIG. 15 shows R in the optical recording medium of Example 4.
It is explanatory drawing which shows the frequency dependence of _f / _Rtop .

[Explanation of reference numerals] 1 ... Substrate, 2 ... Lower surface side dielectric layer, 3 ... Recording layer, 4 ... Upper surface side dielectric layer, 5 ... Quenching reflection layer, 6 ... UV protection resin.

Claims (2)

[Claims] 1. An optical recording medium comprising a multi-layered film provided on a substrate and provided with a recording layer which undergoes phase separation upon irradiation with an energy beam such as light. (A) The recording layer is formed from a composition of a spinodal decomposition region. And (b)
An optical recording medium, characterized in that the multilayer film is configured so that the irradiated recording layer is rapidly cooled after the irradiation of the energy beam such as the light to the recording layer is completed. 2. An optical recording method for writing and reading information to and from a recording layer in a multilayer film provided on a substrate by an energy beam such as light, wherein (a) the recording layer has a composition of a spinodal decomposition region. With the material
(B) The multilayer film is configured so that the irradiated recording layer is rapidly cooled after the irradiation of the energy beam such as the light to the recording layer is completed, and (c) phase separation occurs due to spinodal decomposition. Irradiation with an energy beam such as light having an intensity that causes phase separation due to spinodal decomposition in accordance with the information to be written in the recording layer, which is not performed (d) Phase separation due to the spinodal decomposition does not occur in the written information. An optical recording method comprising irradiating and reading an energy beam such as light having such an intensity.