JPS5968847A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording medium excellent in the recording sensitivity to a laser light, life, resolution, and S/N at reading, by providing a layer including mixture of a metal and at least one oxide such as Al2O3, WO3, and GeO2. CONSTITUTION:The most preferable state of laser recording and reading methods is a method recording and reading information by irradiating a laser beam from a support side. This is introduced from the discovery that no granularity exists at the boundary between the base and a vapor-deposition film even if more or less granularity exists on the surface of a recording layer at the constituent having the highest laser sensitivity, and the excellent S/N is obtained by using the write/reading method. In the write and reproduction from the base side, two bases having a recording layer are fixed via a seak by opposing the recording layer and an air gap is provided between the recording layers (so- called air sandwich type), which are suitable especially, and both side recording is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information recording medium for recording information using a high energy density light beam.

Conventionally, as recording materials using a high energy density light beam such as a laser, there are the following thermal recording materials in addition to photosensitive materials such as silver salts. In this thermal recording material, the recording layer has a high optical density and absorbs the irradiated high-energy-density light beam, causing a local temperature rise and melting.
Information is recorded by undergoing thermal deformation such as evaporation or aggregation, and removing the irradiated area, which causes a change in optical properties such as an optical density difference compared to the non-irradiated area. It is something. Such thermal recording materials generally do not require processing such as development or fixing, do not record in normal room light and therefore do not require darkroom operation, provide high contrast, and are capable of recording additional information. (r
It has the advantage that it is possible to perform

Generally, the recording method on such thermal recording materials involves converting the information to be recorded into an electrical time-series signal, and scanning the recording material with a laser beam whose intensity is modulated according to the signal. There are many cases.

This case has the advantage that recorded images can be obtained in real time.

Because thermal recording materials have the above-mentioned unique features, they have been tried in the past for many uses, such as as a substitute for lithographic film for printing, as recording materials for facsimile, as photomasks for LC, and as microfilms. Some of them have reached the stage of practical application. Because of these numerous uses and applications, many organizations are actively researching the development of recording materials, and the materials used for the recording layer include metals, silastes, dyes, etc. A number of proposals have been made regarding, for example, M,
“Electron Io” by L. LeVene et al.
n and La5er Beam Techn
"Record of the 1st symposium (7962), glectronics magazine (/?g, March 2010/♂
Page 50, “The Bell” by D. Maydan
System Technical Journal
"Magazine! Volume θ (/97/) No. 17/Page, C, O, Ca
rlson, “5science” magazine, Volume 7 (796
6th year) It is described on page 1j, tθ, etc.

In order to incorporate the materials shown in the above-mentioned documents into a practical system, in other words, in order to give them practicality as sensitive materials, it is necessary to add a large number of materials such as supports, recording layers, protective layers, etc. Many patents and patent applications have been filed in the past. It can be said that the most effort has been made to improve recording sensitivity. An overview of past efforts to increase the sensitivity of recording materials using metal thin films is as shown below.

In other words, those using metal thin films such as general +', Bi, Sn, In, Al, Cr, etc. have excellent performance in terms of high resolution and high contrast, but on the other hand, the light reflectance to laser light is - Since most of them are t o 4 or more, the energy of the laser beam cannot be used effectively, so the optical energy required for recording is large. Therefore, a high-output laser light source is required to record with high-speed scanning, so it is difficult to record. This has the disadvantage that the device is large and expensive. Therefore, some recording materials with high recording sensitivity were explored.
I'm here. For example, Japanese Patent Publication No. 6-0417 discloses a recording material having a composition of 8e + B t + Ge. Here, the Qe layer lowers the reflectance of the Bi layer to irradiated light, the Se layer is a layer that evaporates easily, and both JL and JL are used to reduce the reflectance of the Bi layer to the main recording layer with less energy than in the case of a single Bi layer. Thermal deformation of the Bi layer is promoted. Furthermore, the layer for reducing and preventing reflection is made by Tokukai Sho! It is also described in θ-/j//j/ publication and Japanese Patent Publication No. Sho J-/-/4t26λ.

In addition, those provided with a layer for reducing thermal conductivity between the recording layer and its support are described in Japanese Patent Application Laid-open No. 70-/Koi-32 and Japanese Patent Application Laid-Open No. 7402-1989. Also, JP-A Shoj/-7F, No. 236 and JP-A Shoj, 2-20
1.2/ publication describes a recording layer in which a certain metal sulfide, metal fluoride, or metal oxide is layered or mixed with a metal. In addition, Japanese Patent Application Publication No. 2003-110000 JF4t-, +74t, 2 filed by inventors including some of the inventors of the present application
No. 3 (- indicates a recording layer containing a mixture of a functional material and an organic material).

As outlined above, many efforts have been made in the past to increase sensitivity, and as mentioned above, performance has improved to the point of practical use in some areas. However, advances in systems that use recording materials and their peripheral technologies have led to improvements in not only recording materials used for new applications, but also for recording materials used in the aforementioned conventional applications. The current situation is that there is a strong demand for this.

In particular, when thermal recording materials are used for new applications such as optical disk memories, there are very strong demands for higher performance, and it is virtually impossible to satisfy these demands with the recording materials that have been disclosed in the past. It was difficult.

If we now add an explanation of the main performances required of optical DINUC memory materials, they will be as follows. That is, (1) Metropolitan data Ip = high Ie to make it possible:
(2) In order to simplify the optical system, reflective reading of information is preferable, and in order to do so, the recording layer must have a high light reflectance; (3) The long-term stability of recorded information (the highest (4) have high resolution to enable density recording; (5) have high readability. In order to increase the 87N ratio at the time of production, the shape of the recording bit must be good (for this purpose, non-uniformity such as graininess of the recording layer is undesirable) (6) The manufacturing suitability must be excellent (e.g. The evaporation rate during vapor deposition is stable, and during vapor deposition (-no decomposition, etc.) (7) Non-toxicity There are many other performance requirements other than these, but they will be omitted here. Among the above-mentioned performances, (1) and (2) are generally in a contradictory relationship between high reflectance and high sensitivity, as described above.

In addition, materials that exhibit relatively high sensitivity, such as Te thin films,
Generally speaking, it has been difficult to satisfy performance requirements such as long-term stability and toxicity.Also, for the purpose of high sensitivity, low melting point metals such as In%8N are preferred; The thin film tends to have an island-like structure, so (5)
It was difficult to satisfy the performance of

As mentioned above, the performance required of optical disk memory materials is extremely high, and materials that simultaneously satisfy these performances, especially high sensitivity, good long-term shelf life, and non-toxicity, have been found. The reality was that they were not.

In view of these circumstances, the present inventors have been conducting extensive research at 9°C in order to develop thermal recording materials that require high performance, particularly thermal recording materials that are suitable for optical disk memory applications. In the process, it is disclosed in the specification of Japanese Patent Application Laid-open No. 2-0/1999, No. 27, etc. By using a recording layer in which metal and non-metal coexist (by simultaneous vapor deposition method), the above (1) can be achieved.
It has been discovered that the performance of ~(7) is significantly improved.

However, the materials disclosed in the above publication still cannot be said to have sufficient performance, and it has not been possible to find a material that can satisfy both high sensitivity and long-term stability at the same time. Also, for optical disk memory, JP-A-Sho J-4-7
No. 24t/34 discloses an optical recording medium obtained by depositing in and 5I02 on a substrate at a mixing ratio of 5i02 with a volumetric centrifugal ratio of o to 6θ. had the disadvantage that the laser energy required for recording was still not small enough, and a sufficient recording speed could not be obtained during recording.

Therefore, as a result of further intensive research, the present inventors discovered a composition and film thickness of a recording layer that has higher sensitivity than the above-mentioned optical recording medium and has the performance required for the above-mentioned optical D/F memory. This is related to the present invention.

The object of the present invention is to provide an optical disc that is excellent in terms of recording sensitivity to laser light, long-term storage, resolution and reading ratio of 81N among the various performances required of the above-mentioned optical disc, and is inexpensive. The purpose is to provide a recording medium for memory.

Here, the process of implementing the present invention will be explained as follows. In order to satisfy the condition (3) among the performances required for the optical disk memory described above, it is preferable to use a substance that is soluble in water as a metal and is not easily oxidized. In addition, in order to satisfy the conditions of (1), it is best to use a material that is as thin as possible and has a high light absorption capacity, and a material that absorbs laser light and melts. In, which has a low temperature (717°C) and is difficult to oxidize, is suitable, but it still cannot provide sufficient sensitivity due to its high light reflectance.Therefore, the light reflectance is reduced and the thermal conductivity is also reduced. It is expected that the laser recording sensitivity will improve if the compound is mixed with In (a compound that has an effective For example, when the metal fluoride or metal sulfide described in the above-mentioned Japanese Patent Application Publication No. 2022 is allowed to coexist with a metal, hydrolysis of the compound occurs. Oxidation of metals due to the effects of
Decomposition is significantly accelerated.

In addition, the oxides described in the above publications, such as Gem,
Alternatively, when PbO coexists with metal, QeOPbO(7
) Since each of these materials easily changes into GeO2 and PbO2, it has been substantially difficult to obtain a recording material with excellent stability and homogeneity.

In addition, in Japanese Patent Application Laid-open No. Shoj Otsu-/24t/341,
It is stated that by mixing highly chemically stable 5i02 with a θ coefficient of 410 to 10-, the sensitivity is improved, the deposited film is free from graininess, and a reproduced signal with a high .8/N ratio can be obtained. ing. The present inventors have studied the technology disclosed in the above-mentioned publication in detail, and have found that within the scope of the technology disclosed in the above-mentioned publication, satisfactory performance can be obtained in terms of sensitivity and resolution, as shown in the Examples described below. was concluded to be difficult.

Based on the above study results, the present inventors selected an inorganic oxide as a compound to be mixed with metal in order to obtain a recording medium with good sensitivity, storage stability, and resolution.
After examining the effects of composition and film thickness, we found that many oxides exhibit good properties. Furthermore, even when using oxides that exhibit these good characteristics, there is a generally common optimum film thickness and composition range for optimizing sensitivity, S/N ratio, and resolution, regardless of the type of oxide. The present invention was achieved by discovering that.

That is, the present invention is an optical information recording medium characterized in that a layer containing a mixture of a metal and at least one oxide selected from the following group is provided on a support.

Sm2O3, 811203% AIJz03, Ga2O
3%Y2O3s■203, VO2, Ti01Nb2o5
, Hf 02 , MoO2, WO2, WO3, La2O
3, Yb2o3, Sin.

Nd2O3, CeO2, Mn01NiO1 (3e 02
, ZnO1ro2 Among these oxides, the most preferred compound is Al2O3
, Ti01w0.3, CeO2, MoO2, and ZrO2.

A preferred embodiment of the present invention is an optical information recording medium characterized in that the composition ratio of the oxide in the recording layer to the metal is in the range of /θ to daθ in terms of volume ratio. Furthermore, as a preferred embodiment of the present invention, the thickness of the recording layer is ZθθA - θ
Examples include the above-mentioned optical information recording medium that is oh.

Examples of metals used in the recording layer of the present invention include Mg, Sc
, Y, Ti, Zr, Hf, V, Nb, Ta.

CrsMe, W, 1lJn, Re, pe%Co, N
i.

Rh, Pd, Ir%Pt, Cu, Ag, Au, Zr, C
d% A1% Gax In, si, Ge, S
u, As.

8b, Bi, Se, and Te, and among these metals, Mg, Zn,
AA', In, Bi, etc. are suitable. As a result of various studies, it was found that In is optimal because it has a low melting point, has high sensitivity, and is chemically stable, so it has good storage stability.

The reason why the preferred composition of the oxide in the present invention is set to 200A, which is a preferable film thickness, is as follows.

That is, (1) As understood from the examples, the sensitivity improvement is particularly large in the io-gθ range, and when the oxide ratio is 10
% or less, turbidity tends to occur at the deposition layer/substrate interface, reducing the S/N ratio during reproduction.

(2) If the film thickness is less than θθA, the light absorption rate will be small and the sensitivity will be decreased, and if it is more than 00λ, the sensitivity and resolution will be decreased.

73- Note that the most preferred embodiment of the laser recording/laser reading method in the present invention is a method of recording and reading by entering a laser beam from the support side. The reason for this is
This was derived from the discovery by the present inventors that in the above composition range where the laser sensitivity is highest, even if there is some graininess on the surface of the recording layer, there is no graininess at the interface between the substrate and the deposited film. - A better 8/N ratio can be obtained by using the reading method.

Here, writing and reproducing from the board side are performed, for example, in Japanese Patent Application Laid-Open No. 6
2-Ijttθ! The structure of the sensitive material disclosed in the publication is specifically a structure in which two substrates each having a recording layer are fixed to each other through a seal with the recording layers facing each other, with an air gap between the recording layers (commonly known as It is particularly suitable for the air sandwich type), and can have various advantages such as being able to record on both sides. The present invention is particularly preferable also from the viewpoint of such a structure of the sensitive material.

Suitable supports for use in the present invention include polyethylene terephthalate, polymethyl methacrylate and their weights, plastics such as polycarbonate, and glass.

One method for forming the recording layer of the present invention is to use two evaporation sources in a vacuum chamber, a resistance heating evaporation source for 7n and an electron gun for oxide, and perform the evaporation simultaneously. The mixing ratio of both can be controlled by arranging a crystal vibration type film thickness monitor for each evaporation source and controlling the evaporation rate thereby.

In addition to the methods described here, known thin film manufacturing methods such as s/ξ stumbling and ion silating can be used.

Further, between the recording layer of the present invention and the support, an appropriate intermediate layer may be further provided by coating, vapor deposition, or other means for the purpose of increasing sensitivity or preventing the recording layer from peeling off. For example, organic substances such as halogenated polyolefin, halogenated polyhydroxystyrene, chlorinated rubber, and nitrocellulose, and nonmetals such as SiO, 5iO2 are preferable.The thickness of this heat insulating layer is θ, or μm.
-3θμm is suitable, but particularly preferably Ol, 2μm
~3θμm.

In the recording material of the present invention, a protective layer made of an inorganic or organic substance may be provided on the recording layer provided on the support.

Providing a protective layer on the recording layer is effective in improving the durability, mechanical strength, stability over time, etc. of the recording material, and is of course a preferred embodiment of the present invention. .

The protective layer may be made of either an inorganic or organic material, but it must be transparent to the high-energy density light beam used, have high mechanical strength, be difficult to react as a recording layer, and be coated. It is required to have good properties and be easy to manufacture.

The protective layer used in the present invention may be made of either an inorganic substance or an organic substance. For example, as a protective layer of a bear machine, A7203, StO
r i 02.7. Transparent materials such as r 02, MgF2, CuF2 are preferred. These are formed by vacuum evaporation, snootering, ion plating, etc.

It is also an excellent method to use organic substances as a protective layer. Various resins can be used as the protective layer, including styrene resins such as polystyrene and styrene-maleic anhydride resins, vinyl acetate resins such as polyvinyl acetate, polyvinyl alcohol, phthalate, and polyvinyl formal; Methacrylic acid ester resins such as polyisobutyl methacrylate and polymethyl methacrylate; amide resins such as polydia-7ton acrylamide and polyacrylamide; It is selected from vinyl chloride, polyhalogenated olefins such as chlorinated polyethylene, phenolic resins, soluble polyesters, soluble nylons, gelatin, and copolymers thereof.

These resins can be dissolved in various solvents and applied by known coating methods.

There are various solvents that can be used, such as acetone, methyl ether ketone, methyl isobutyl ketone, methyl cellosolve, etel cello 72-solp, butyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, hexane, cyclohexane, and ethylene. Chloride, methylene chloride, benzene, chlorobenzene,
The resin used may be selected from methanol, ethanol, butanol, petroleum ether, dimethylformamide, thinner, etc. depending on the resin used.

Various additives such as pigments, matting agents, plasticizers, and lubricants can be added to these resins depending on the purpose. In particular, higher fatty acids or acid amides having a carbon number of 77 or more can be added. 0. Addition of about /~/, Owt% is effective in improving the film surface strength of the recording material.

It is also possible to apply a lubricant such as these higher fatty acids or acid amides to a thickness of θ, 007 to /μ by a conventional method on the protective layer. The thickness of the protective layer used in the present invention is selected to be the optimum thickness in consideration of the film surface strength, stability over time, recording sensitivity, etc. required as a recording material.
A film thickness of /μ to jθθ−/r−μ is preferable.

As another form of the protective layer, it is also possible to form the protective layer in such a manner that an air gap is provided between the recording layer and the protective layer, as disclosed in the specification of Japanese Patent Laid-Open No. 1982-146θj. In particular, double-sided recording is possible in a form (commonly known as an air sandwich type) in which two supports on which recording layers are formed are fixed with the recording layers facing each other via a seal.
When a large capacity of information storage is required, such as in an optical disk memory, (: is one of the most suitable formats.

As mentioned above, the recording material of the present invention is most suitable for optical disk memory applications, but it can also be used as a substitute for printing lithographic film, facsimile recording materials, IC photomasks, microfilms, etc. 1
-It is not limited.

The present invention will be specifically explained below using examples.

Example / On a polyethylene terephthalate support with a thickness of 7002 m, In and oxides were deposited under vacuum conditions of j×/θ−' Torr, In was prepared using a resistance heating evaporation source, and the oxide was prepared using an electron gun. Vapor deposition was performed at the same time. The mixing ratio of both was controlled by placing a crystal vibration type film thickness monitor for each evaporation source, and controlling the evaporation rate thereby to produce a recording medium.

For comparison, a method similar to that described above was used except that a ceramic source of Sn, 8n8 was vapor-deposited using resistance heating.
2-. 2θ/, Sn and 8n disclosed in Publication No. 27
A recording medium having a mixed layer of S was obtained.

Sample 1 prepared as above: Beam diameter/~2μ
The writing thresholds (laser powers) of the recording media were compared by irradiating the recording medium with an Ar laser beam of 100 nsec in a stationary state. The writing threshold at this time was determined using an optical microscope.

Table 1 shows changes in the write threshold when the oxide material mixed with In is changed. The recording layer thickness at this time was 4tOoA, and the oxide composition ratio was
2 cents. t%.

From Table 1, compared to the mixed layer of Sn and 8nS disclosed in JP-A No. 32-201.27, all oxides mixed with in have the same sensitivity, or even better than that of U. The largest one showed a three-fold increase in sensitivity. Also, Tokukai Akira! Mixed layer of In and 5i02 (total thickness 10oooh) disclosed in Ko-1 No. 7.2411341
, 8i02 volume/G1 centa θ ~ 0%), we measured the write threshold in the same way, and found that the first
As shown in the table, sufficient sensitivity could not be obtained.

27- Example The thickness of the recording layer was kept constant (1
Samples were prepared by changing the composition ratio of In and WO3 (00A), and the laser recording sensitivity was compared using the same method as in Example/.
Good recording sensitivity was exhibited within the range of .theta. (Fig. 1).

Example 3 A sample was prepared in exactly the same manner as in Example 3 except that Al2O3 was used as the oxide, and laser sensitivity evaluation was performed. It showed good recording sensitivity in the range (
Figure 2).

Example In, WO3, Al2O3 by the same method as Example/
, mixed layer with GeO2 (total thickness 4tooA, WO3, A
12O3, Q e O2 volume percentage Jj) were prepared, and each of them and Sn used in Examples
The nS recording medium was placed in a constant temperature and humidity bath at 0%RH, and the change in optical density over time was investigated (Fig. 3). in and W as shown in this figure
O3, AA! It was found that the recording medium with the mixed layer of 20a and Q e 02 had a significantly improved reduction in optical density over time compared to the 8n+SnS one.

Example (1) Optical information recording medium (2) Recording according to the claims, characterized in that the composition ratio of the oxide in the recording layer is /θ to θ in terms of volume ratio to the metal. Layer thickness is 200A
-Otsu θθA (3) Optical information recording medium characterized in that the metal in the claims is In.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the composition ratio dependence of the write threshold of an In and WO3 mixed layer, FIG. 2 is a diagram showing the composition ratio dependence of the write threshold of an In and Al2O3 mixed layer, and FIG. The figure is a diagram showing a decrease in optical density of a recording medium due to a forced deterioration test. -, 2j- Figure 1 To WO3ite l°-self (%) Figure 2 0 20 40 60
B0A1'203 I. 80-Death Int (%) 3 Figure Procedural Amendment (Showa JIr, October 1999/Japan Head 1) Commissioner of the Japan Patent Office 1, Indication of Case 1982 Patent Application No. 17171
No. 7 No. 2, Title of the invention: Optical information recording medium 3, Relationship to the amended person's case Patent applicant address: 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (520) Fuji Photo Film Co., Ltd. Telephone: (406) 2537 4. Subject of amendment Column 5 of “Claims” of the specification and “Detailed explanation of 1 invention” of the specification, contents of amendment (1) The column of “Claims” of the specification should be changed as shown in the attached sheet. to correct. (2) In the specification, page 12, line 12, and page 2j', line 7, ``with respect to metals'' is amended to ``with respect to the sum of metal and oxide.'' (3) "Heavy body" in the first line of page 1j of the specification is corrected to "copolymer." (4) "Oxide" in the first line of page 21 of the specification is amended to read "specific oxide of the present invention." (5) On the first page of the specification, insert 1'-, a mixed layer of In and GeO, and a mixed layer of In and SiO, next to "...centpo-ao%)" in line 1/-. (6) Table 1 on pages 22 and 23 of the specification is replaced with the attached one. Above 2 - Attachment ``Claims'' ``A metal on a support and at least 7 metals selected from the following group.
1. An optical information recording medium comprising a layer containing a mixture of two oxides. Sm O, Eu OAlO, Ga2O3, Y2O3,2
323-23 VO, VO, TtO, Nb2O5, HfO2, 232 Mo O-WO-WO-L a 20 a, Yb2O3
,223 ZrO1Nd203, CeO2, Mn01NiO1G
e O2, n0oJ 278-

Claims (1)

[Claims] An optical information recording medium characterized in that a layer containing a mixture of a metal and at least seven oxides selected from the following group is provided on a support. ”m20:4% B11203% A6zO3s Ga
2O3% Y2O3゜Y2O3, v02, Ti01Nb
206, HIO2, Y6O2, WO2, W03% T
, a203, Yb2O3,8i0, Nd2O3, Ce
02, Mn0%Ni01Qe O,! , ZnO1Z r
02゜