JPS61153839A - Optical memory medium - Google Patents

Abstract

PURPOSE:To obtain the titled optical memory medium capable of performing multiple recording and reproduction with high sensitivity and high density by dispersing >=2 kinds of fine metallic blocks having different wavelength showing a light absorption maximum into a hold-back body (a binder) reacting with the metallic block by the irradiation of the light having specified wavelength. CONSTITUTION:A block of a single fine particle or aggregated fine particles of Ag having the high absorption maximum at 430nm and Au having the maximum at 560nm and having respectively 10-1,000Angstrom diameter, for example, is dispersed in a reactive binder such as an ethylene-acrylic acid copolymer and an epoxy resin wherein the light absorption maximum is vanished by the reaction of the metallic fine particle with the binder under the irradiation of an excimer laser beam 1 of 350nm wavelength to obtain a recording layer 8 which is formed on a substrate 7. When the excimer laser beam 8 is irradiated on the memory medium thus obtained, the respective absorption maxima of the respective metals are vanished at the irradiated part 91, whereas the absorption maximum at the unirradiated part 92 is not vanished. When an XeF laser is irradiated, only the absorption maximum of Au remains at the irradiated part, and only the absorption maximum of Ag remains, when a KrF laser is irradiated. By utilizing the phenomenon and selecting the wavelength of the recording and reproducing light, a memory medium 6 capable of recording and reproducing in three ways is obtained.

Description

[Detailed description of the invention] [Techniques of invention (A1 field)] The present invention relates to optical memory media.

['Technical history of the invention and its problems]

2. Description of the Related Art As a memory medium capable of recording information signals with high density, there is known an optical disk in which information signals are recorded as structural changes and reproduced optically. This type of optical memory medium has conventionally formed a recording layer of a metal thin film made of bismuth, tellurium, etc. on a glass or plastic substrate.
A method has been adopted in which information is recorded by forming bits using melting and evaporation caused by focused laser light. However, since the recording layer of such a gold B thin film generally has a high melting point, the recording sensitivity is low, and furthermore, the recording density on the metal thin film recording layer is regulated by the circumferential area of the condensed laser beam. There was a problem in that it was also difficult to improve.

[Purpose of the invention]

The present invention aims to provide an optical memory medium that is highly sensitive and capable of high-density recording.

(Summary of the Invention) The present invention provides two or more types of minute metal lumps whose light absorption maximum changes when irradiated with light of a specific wavelength and whose wavelengths exhibit different light absorption waves, and a metal lump in which these metal lumps are dispersed. The present invention is characterized in that it includes a reactive support that reacts with the metal mass when irradiated with light of a specific wavelength.

The present invention will be explained in detail below.

It is generally known that when metals are made into ultrafine particles, they exhibit remarkable light absorption characteristics at specific wavelengths centered around the visible range. For example, it is known that gold colloid is colored pink, and the edge of a silver mW pattern is colored pale red. The light absorption characteristics of such fine metal lumps in the visible range are
This is thought to be due to surface plasma resonance absorption of fine metal particles. The absorption wavelength and degree of absorption are determined by the Fermi velocity (vf), the effective number of free electrons (neff), and the effective quality @(
It is closely related to the free electron plasma state such as (meff).

The present inventors focused on the relationship between the light absorption characteristics of the metal lump and the free electron plasma state, and if it is possible to change the free electron state by light beam irradiation, recording will be performed by light irradiation. This is possible due to the difference in the light absorption spectrum of the metal block before and after light irradiation. It is now possible to play back the recorded state, creating a new optical memory medium, and recording and playback can be done with high sensitivity using photon mode.
Based on the idea that it is possible to realize a high-density and highly durable optical memory medium, as a result of extensive research, we have found that a fine T8 metal block can be made of thermoplastic resin, thermosetting resin, or other suitable material. When a reactive carrier such as a plasma polymerized film containing a functional group is dispersed and irradiated with light such as an argon laser for recording purposes, a remarkable change in light absorption characteristics appears, and recording and reproduction are possible based on the above principle. , even different V! Even when different kinds of metal lumps coexist, the light absorption characteristics change independently depending on each type of gold MIII-like material, making multi-recording possible.
Based on the knowledge that multiple playback is possible, the present invention was completed. The causes of such changes in the light absorption properties of fine metal lumps include reactions between specific metal lumps and reactive carriers due to light irradiation, as well as changes in the dispersion state of specific metal lumps. It is conceivable that the state of the holder around the specific metal block may change. Such changes occur mainly based on light energy,
Since this is a change in the so-called photon mode, when metal lumps with different light absorption characteristics coexist, it is thought that each gold R lump with light absorption characteristics will respond independently to light at a specific wavelength. .

The above-mentioned metal lumps include intermediate particles of ultrafine metal particles and aggregates of ultrafine metal particles. The material of this metal block is not particularly limited, but it is preferable that the electronic state that influences the optical properties of the metal is free electron (or S-electron) based on the above-mentioned recording/reproduction principle. in particular,
Examples include noble metals such as Ag and AU%Pt, alkali and alkaline earth metals such as Be and Mq, and Cu, which has relatively weak d-electronic (local) imaging. Such metal lumps may be used alone or in mixtures. The diameter of each such metal mass is preferably in the range of 10 to 1000. The reason for this is, is it possible to make the diameter less than 10 people? However, if the optical absorption maximum in the R region does not occur and the diameter of the ultrafine metal particles exceeds 1000, the optical absorption maximum becomes weak, the S/'N ratio decreases, and reproduction becomes difficult. The recording density decreases by 1r to get closer to the optical beam diameter for recording and reproduction! <. Further, it is desirable that the volume content of the metal block in the reactive support is in the range of 0.01 to 50%. The reason for this is that its content is o, 01%
When the content is less than 50%, the light absorption maximum becomes weak, and on the other hand, when the content exceeds 50%, the light absorption maximum does not appear.

The reactive support for dispersing and holding the metal lumps may be any material that can chemically or physically change the dispersed metal lumps by irradiation with light.

In particular, in order to make the light absorption characteristics of the metal block that influences reproduction sensitivity more remarkable, it is preferable that the metal block has a refractive index of 1°3 or more. Specifically, polymethyl methacrylate, polymethyl methacrylate,
ABS resin, ABS resin, cellulose resin, polyamide, polycarbonate, polyacetal, borisdylene, PVC, /FFM polyvinyl chloride copolymer,
Thermoplastic resins such as polyvinyl butyral, P P 081 resin, borisulfone, etc., thermosetting resins such as unsaturated polyester, epoxy TF16, polybutadiene, polyimide, or acrylic acid, methane, acetaldehyde, methanol, acetone, Examples include plasma polymerization samples obtained by appropriately blending raw material gases having divine functional groups such as acrylonitrile.

(Example of the invention) Examples of the present invention will be described in detail below.

Examples 1 to 3 First, a quartz vat is filled with aromatic glycidylamine (Nippon Kayaku al trade name: GAN), and ACI and A are placed on the liquid surface.
After alternately vapor-depositing epoxy resin (Shell'Tama product name: Ebicoat 1001) and polyamide (Sanyo Chemical Co., Ltd.
(3) Product name: Bolimide-25) and methyl ethyl ketone as a diluent and xylene were mixed to prepare a solution. Subsequently, the solution was spin-coated onto a glass substrate and cured, thereby producing an optical memory medium having a recording layer made of a resin containing aggregates of Ag and Au (ultrafine particles) dispersed in the resin. Shita. At this time, by carefully changing the conditions of Ag and Au vapor deposition source temperature, inert gas pressure, and vapor deposition time, and further changing the resin composition, the particle size of the ultrafine particles shown in the table below, and the mixing of Ag and Au. 3 fl recording layers (Examples 1 to 3) having different ratios, volume contents in resin, and film thicknesses were formed. The volume content was determined by chemical analysis, and the particle size was determined by ionizing evaporated particles (clusters) and performing stratigraphic analysis using their mass spectra.

Next, characteristic evaluation of the optical memory medium of Example 2 will be described in detail using the apparatus shown in FIG.

Figure 1 measures the characteristics of an optical memory medium (average ratio 1.5 W, 100 pulses/sec, beam diameter: 3 μm), 2 > (e lamp, 3 spectrometer, 4
5 indicates a focusing lens, and 5 indicates a photodetector. Excimer lasers include XeF lasers with a wavelength of 350 nm and wavelength 3
A 50 nm KrF laser was used.

The aforementioned Xe lamp 2, spectrometer 3, focusing lens 4, and photodetector 5 constitute a detection system. In addition, 6 in the figure
is an optical memory medium consisting of a glass substrate 7 and a recording W 48 formed thereon.

In the apparatus configured as described above, first, three memory medium samples (A to C) similar to those in Example 2 were prepared. Next, input power to excimer laser 1 and perform 1 sec
During this period, the portion indicated by 91 of the recording layer 8 of sample A was repeatedly irradiated with the XeF laser at shore 1.
A detection system consisting of an e-lamp 2, a spectrometer 3, a lens 4, and a photodetector 5 is set at the position Pl in FIG.
It was irradiated with scanning medium color light of 0 to 800 nm, and the spectral intensity distribution of the transmitted light was measured by the detector 5.

Next, the detection system is moved to position P2 in FIG. 1, and the 11-color light is scanned and irradiated to the 92 part (laser non-irradiated part) of Record @ 8, and the spectral intensity of the transmitted light of the part 92 is measured. The distribution was measured. Similar operations were performed on sample B (recording was performed only with a KrF laser) and sample C (recording was performed using both a XeF laser and a KrF laser), and the The spectral intensity distribution was measured. Based on these measurement results, the profile of the transmitted light spectral distribution of the optical memory medium of Example 2 shown in FIG. 2 was determined.

Note that N in Figure 2 is the transmitted light spectrum distribution characteristic line of the laser-unexposed area drilled in the recording layer of the memory medium, and Xe is
The same distribution characteristic line of the recording layer portion irradiated with only the F laser is
B1. C shows the same distribution characteristic line of the recording layer portion irradiated with only the t K r F laser, and C shows the same distribution characteristic line of the recording layer portion irradiated with both the XeF laser and the KrF laser.

As is clear from Fig. 2, in the unirradiated part of the excimer laser, plasma resonance absorption (center wave f%4
30 nm) and plasma resonance absorption of the A u IA-like body (center wavelength 560 nm) are detected in a shared manner. On the other hand, from the part irradiated only with the XeF laser, only the plasma resonance absorption of the Au 159-like body was observed, and the KrF
From the laser irradiated area, only plasma resonance absorption by the q lumps is obtained, and furthermore, from the simultaneously irradiated area with the XeF laser and the Kl-F laser, a flat transmitted light spectrum distribution is obtained. For these reasons, AQ masses and ALI
Even if agglomerates exist mixed in the laser irradiation area, depending on the recording laser selection, only AQ agglomerates or △U
Recording of 3 types of lumps only or both AQ and Au lumps (
If the wavelength of the reproducing light beam is selected (for example, 43Q'nm corresponding to 80, 560nm corresponding to Au), the above 3. We confirmed that playback compatible with street recordings is possible.

Note that, following the optical memory medium of Example 1.3, the first
Characteristic evaluation similar to Example 2 was carried out using the apparatus shown in the figure.
As in the second embodiment, it was possible to perform recording and reproduction in three ways.

Example 4 Example 4 is an example of an optical memory medium manufactured by a dry process using the manufacturing apparatus shown in FIG.

FIG. 3 is a schematic diagram showing an optical memory medium manufacturing apparatus. In the figure, 11 is the discharge point, 121 is the first gas supply system, 122, 122- is the second gas supply system, 13 is the exhaust system, 14 is the high frequency coil, 15 is the high frequency power supply, 16 is Aq
A lump, 16' is an AU lump, 17.17- is a hollow cathode gun, 78.18- is a porous orifice, 1, 1- is a shutter, 20 is a deep support plate for the object to be processed (glass board) are shown respectively.

Next, a method for manufacturing an optical memory medium using the above-described apparatus shown in FIG. 3 will be described.

First, after fixing the glass substrate 7 to the holding plate 20,
Close the Yatta 19 and 19', apply power to the hollow cathode gun 17, emit an electron beam to the AQ lump 16, and supply H2 gas from the second gas supply system 122 to
A fringe lump that was finer than the surface of the lump 16 was sputtered. Next, the first gas supply system 12 is connected to the discharge machine 11.
Ethylene-acrylic acid mixed gas is introduced from 1, and the high-frequency power supply 15 is turned on to generate a fi of the mixed gas of ethylene-acrylic acid and H2 that has already been introduced around the high-frequency coil 14.
l'1 is carried out, and at the same time the shutter 19 of the 16 cases of g15tl-like objects is opened, and the fine AQ lumps generated from the surface of the AQI onishi object 16 are guided to the surface of the substrate 7 along with the H2 airflow from the second supply system 122. A plasma polymerized film containing C, H, and 0 dispersed in an AQ-related suspension was formed on the substrate 7. Next, the shutter 19 is closed, ALJ lumps are generated from the surface of the Auu-like object 16' by the same operation as in the case of AQ, and the shutter 19' is opened to transfer the ALJ 111-like object to the gas supply system 1.
22- C, H, and O were introduced onto the surface of the substrate 7 together with the H2 gas flow introduced from 22- to disperse ALJ aggregates on the substrate 7.
A plasma polymerized film containing the following was formed. These AQs,
The process of forming a plasma polymerized film containing AU was repeated twice to form agglomerates of 80 and AU at 0.2VO1% and 2.3V0, respectively.
An optical memory medium was prepared in which the recording layer was a plasma polymerized film containing 1%. The mixing ratio of the mixed gas and the gas pressure in the electrolyte chamber 11 were set to such conditions that the formation of the plasma polymerized film on the substrate 7 would proceed.

When the optical memory medium of Example 4 was evaluated in the same manner as in Example VA2 using the measuring device shown in FIG.
It was confirmed that recording and playback could be performed as required.

(Effects of the Invention) As detailed above, according to the present invention, in order to perform recording and reproduction using photon mode, multiple types of Provides an optical memory medium that makes it possible to disperse metal lumps with unique light absorption characteristics, thereby achieving high sensitivity and a dramatic improvement in recording density (multi-recording/playback). can.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a measuring device used to evaluate the characteristics of an optical memory medium according to the present invention, and Fig. 2 shows three types of excimer irradiated and unirradiated areas of the recording layer in Example 2 of the present invention. FIG. 3 is a schematic diagram showing the optical memory medium manufacturing apparatus used in Example 4. 1... Ex7 laser, 2... Xe lamp, 3...
- Spectrometer, 5... Photodetector, 6... Optical memory medium, 7... Glass substrate, 8... Recording layer, 11...
1L12+, 122.122-...-Gas supply system,
15...High frequency power supply, 16...Ag lump, 16'
...Au l demon, 17.17'... Holo cathode gun, 19.19'... Shutter. Applicant's agent Patent attorney Takehiko Suzue Figure 2 Depth length (nm)

Claims (3)

[Claims] (1) The light absorption maximum changes due to light irradiation with a specific wavelength,
and two or more types of fine metal lumps having different wavelengths exhibiting maximum light absorption, and a reactive support in which these metal lumps are dispersed and which reacts with the metal lumps when irradiated with light of a specific wavelength. An optical memory medium comprising: (2) The optical memory medium according to claim 1, wherein the volume content of the fine metal lumps in the reactive support is in the range of 0.01 to 50%. (3) The optical memory medium according to claim 1, wherein each fine metal lump has a diameter in the range of 10 to 1000 Å.