JP2003331470A - Optical recording medium and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium which is high in preserving reliability at and under a high temperature and high humidity, makes a high- temperature operation stable, mechanical characteristics good and productivity high and makes high-speed reproducing and high-speed recording possible. <P>SOLUTION: 1. The optical recording medium has at least a first protective layer an optical recording layer, a second protective layer, a third protective layer (surface reforming layer) consisting of a material containing ≥35 mol% Si atoms, and a light reflection layer consisting of a material containing ≥95 wt.% Ag in this order on a substrate, and further has a resin protective layer and/or adhesive layer on the light reflection layer, in which the film thickness DM of the third protective layer ranges from 2 to 9 nm. 2. The method for manufacturing the optical recording medium comprises forming the films of both layers under the conditions of 0.02≤Rm/Rr≤0.20 and 0.5 nm/sec≤Rm≤5.0 nm/sec when the film forming speed of the third protective layer is defined as Rm and the film forming speed of the light reflection layer as Rr. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CD-R, a CD-recorder capable of reproducing or recording information by irradiation of laser light.
RW, DVD-ROM, DVD-R, DVD-RW, D
The present invention relates to an optical recording medium such as VD + R, DVD + RW, DVD-RAM and the like, which is capable of high-speed recording, particularly 12 m / sec (seconds) or more.

[0002]

2. Description of the Related Art CD-DA, CD-ROM, VI as an optical recording medium which can be reproduced or recorded by irradiation of laser light.
DEO-CD, CD-R, CD-RW, DVD-VID
EO, DVD-ROM, DVD-R, DVD-RW, D
VD + R, DVD + RW, DVD-RAM, etc. have been commercialized. In order to enable more information to be recorded faster in these recording media, higher recording densities and higher linear velocities are expected, and the solution is to adopt an Ag-based light reflecting layer. Is being considered. When Ag is used as the light reflecting layer of an optical recording medium, the following merits are expected. However, in order to secure these merits, it is desirable to use Ag having a purity of 95% by weight or more. (1) Improvement of reproduction ability by increase of disc reflectance in a wide wavelength range (2) Improvement of reproduction ability by increase of signal amplitude caused by optical characteristics of Ag (3) In case of light reflection layer of phase change disc, Improvement of overwrite performance by layer structure with faster cooling rate (4) In the case of light reflecting layer of phase change disk, recordable linear velocity range is expanded by layer structure with faster cooling rate (5) Productivity by high sputtering efficiency (6) Reduction of thermal stress by shortening sputter film formation time (improvement of disk mechanical characteristics)

On the other hand, when Ag is used as a light reflection layer of an optical recording medium, there are the following problems. (1) Easily corroded under high temperature and high humidity. (2) Easily corroded by sulfur or chlorine. (3) The film adhesion to the base is small. (4) It is a noble metal and is more expensive than Al or the like for a general-purpose reflection layer. As a method for suppressing Ag corrosion, JP-A-57-18 is known.
6244, AgCu, JP 7-3363, AgMg, JP 9-156224, AgOM.
(M: Sb, Pd, Pt), Japanese Patent Laid-Open No. 2000-28551.
The alloying of Ag as found in AgPdCu in JP-A-7 is known. Further, in Japanese Patent No. 2749080, in order to control the thermal conductivity, Ag is added to Ti,
V, Fe, Co, Ni, Zn, Zr, Nb, Mo, R
h, Pd, Sn, Sb, Te, Ta, W, Ir, Pt,
It is disclosed to contain Pb, Bi and C. However, when these material systems are actually used for the light reflection layer, the DV
When D + R discs and DVD + RW discs were produced and the archival high temperature storage reliability of these optical recording media at 80 ° C. and 85% RH was evaluated, a sharp increase in errors was observed after 300 hours of storage. Sufficient storage reliability was not obtained.

As a means for suppressing the corrosion of the reflective layer, it has been customary to form an ultraviolet curable resin layer on the surface of the reflective layer. For example, Japanese Patent Laid-Open No. 2001-222842 discloses that by setting the glass transition temperature of the resin to 45 ° C. or higher, wrinkles due to water absorption of the resin can be eliminated, and corrosion of the Al reflective layer can be avoided. However, in the experiments conducted by the present inventors, even when the resin having a glass transition temperature of 80 ° C. disclosed in the above publication was used, corrosion or an increase in reproduction error occurred in the case of the Ag-based light reflecting layer. Further, in the phase change type optical recording medium, ZnS.SiO ₂ (20
It is effective to form a (mol%) film. As this material, a material having optimized thermal expansion coefficient, optical constant and elastic modulus is used. However, when an Ag-based light reflection layer is used for high-speed recording of a phase change optical recording medium, ZnS
-If an Ag-based light-reflecting layer is formed directly on SiO ₂ , Ag
It is known that and S of ZnS.SiO ₂ react to cause corrosion of the reflective layer.

As a countermeasure for this, Japanese Patent Laid-Open No. 11-23825
No. 3, in order to prevent a chemical reaction between a sulfur atom in a protective layer of a phase-change optical recording medium and an Ag-based light reflecting layer, T.
a, Ni, Co, Cr, Si, W, V, C, Si, A
It is disclosed that an intermediate layer using u, Pd, Ag oxide, Al oxide, and Ta oxide is provided, and as the film thickness, corrosion resistance is maintained and high thermal conductivity of the Ag-based light reflection layer is effective. It is described that 40 nm is suitable for use in the above, and that there is no problem in signal characteristics and storage reliability at 80 ° C. and 85% RH when the thickness of the intermediate layer is 10 to 50 nm. But,
When the present inventors produced a phase change optical recording medium using these materials as an intermediate layer, the intermediate layer thickness was 10 to 50 nm.
In, the signal characteristics depended on the thickness of the intermediate layer, and practical signal quality could not be obtained. In addition, the rate of temperature rise and fall 10
℃ / hour, 25 ℃ 95% RH 12 hours and 40 ℃ 95%
In the heat cycle test of 6 times for 12 hours of RH, there was a problem that the Ag-based light reflecting layer was peeled from the intermediate layer. That is, according to the results of studies by the present inventors, although the reaction between sulfur and Ag in the protective layer is suppressed by the formation of the intermediate layer, the adhesion between the intermediate layer and the Ag-based light reflecting layer is not sufficient, and both layers are not formed. It was found that the film adhesion of No. 1 decreased due to high humidity and dew condensation. This is because the chemically inactive intermediate layer is provided to suppress the mutual diffusion to suppress the corrosion of the Ag-based light reflecting layer, and as a result, the film adhesion between the intermediate layer and the Ag-based light reflecting layer, particularly, the film due to humidity. This is probably because it was no longer possible to prevent the decrease in adhesion.

[0006] Further, Japanese Patent Laid-Open No. 2000-2000, which is a prior application of the present applicant.
No. 331378 discloses an upper part which is in contact with the reflective heat dissipation layer.
As the dielectric protective layer, AlN, SiNx, SiAlN,
TiN, BN, TaN, Al_TwoO_Three, MgO, SiO,
TiO_Two, B_TwoO_Three, CeO _Two, CaO, Ta_TwoO₅,
ZnO, In_TwoO_Three, SnO_Two, WC, MoC, Ti
C or SiC is used, and the upper dielectric protective layer is formed in a multilayer structure.
The upper dielectric layers 4, 5 (second of the present invention,
(Corresponding to the position of the third protective layer) 7 to 60n
m, preferably 10 to 30 nm is disclosed.
Has been. However, as an example, the third protection of the present invention
The film thickness of the upper dielectric protective layer 2 corresponding to the position of the layer is
An example is shown in which the thickness is 10 nm, which is thicker than the numerical limit range of the present invention.
However, there is no example of 9 nm or less. Also,
In the upper dielectric protective layer consisting of two layers,
A without changing the basic optical design and thermal design drastically
In order to significantly improve the reliability of the g-based light reflection layer,
The protective layer that is not in contact with the heat dissipation layer (the second protective layer in the present invention)
Prevents Ag corrosion without adversely affecting the function of
Therefore, the protective layer (the third layer in the present invention) that is in contact with the reflection / heat dissipation layer is
The technique of providing a protective layer) as a thin surface modification layer
The technical idea is not disclosed in this prior publication.

Moreover, as will be described later, even when a material containing 35 mol% or more of Si atoms is used as the material of the third protective layer, when the film thickness becomes 10 nm, the initial signal characteristics and 95% RH under high humidity are obtained. Is not sufficiently reliable (see Comparative Examples 3 to 7 in Table 2), and the material (SiO,
Even if a third protective layer having a film thickness of 9 nm or less is provided by using a material other than (such as SiC), the same effect as the present invention cannot be obtained (see Experiments 1 and 16 in Table 1). Therefore, in the publication of the prior application, among the many materials for the upper dielectric layer illustrated, S
It can be said that there is no description or suggestion that only a material containing 35 mol% or more of i atoms exerts a selective and superior effect as compared with other materials.

In summary, the above-mentioned Japanese Patent Laid-Open No. 11-2382.
Although JP-A-53-53 and JP-A-2000-331378 describe the use of Si or a material containing Si for the intermediate layer or the dielectric protective layer, these are cited as comparative examples in the present invention. It is only described as one of the equivalents with many other materials including those described above, and the inherent effect selectively possessed only by the material containing 35 mol% or more of Si atoms is neither described nor suggested. In view of the fact that the film thickness is not present and the film thickness is thicker than the numerical limit range (2 to 9 nm) of the present invention, the film thickness range in which the object of the present invention cannot be achieved is described as a range in which uniform effects are exhibited. Obviously, the technical idea of the present invention is not disclosed. Further, in these publications, the definite sputtering conditions of the Si-containing intermediate layer or the dielectric protection layer, the film structure which depends on the conditions, the film quality, the environmental reliability and the recording signal characteristics based on the film quality are described. Nothing is disclosed about the optimal film thickness based on the balance of the above.

[0009]

DISCLOSURE OF THE INVENTION The present invention provides an optical recording medium having high storage reliability under high temperature and high humidity, stable high temperature operation, good mechanical properties, high productivity, and high speed reproduction or high speed recording. The purpose is to provide a recording medium.

[0010]

[Means for Solving the Problems] The above problems are solved in the following 1) to
It is solved by the invention of 24). 1) At least a first protective layer, an optical recording layer, and a first
2 Protective layer, made of material containing 35 mol% or more of Si atoms
The third protective layer, light made of a material containing 95% by weight or more of Ag
A reflective layer is provided in this order, and a resin protective layer is further provided on the light reflective layer.
And / or an optical recording medium having an adhesive layer.
The thickness DM of the protective layer is in the range of 2 to 9 nm.
And an optical recording medium. 2) The film thickness DM of the third protective layer is in the range of 3 to 7 nm.
The optical recording medium as described in 1) above. 3) The third protective layer is made of only Si.
The optical recording medium according to 1) or 2). 4) The third protective layer contains Si, C (carbon) and O (oxygen).
The optical recording medium as described in 1) or 2) above. 5) The third protective layer is made of a mixture of SiC and SiOx.
The optical recording medium as described in 4) above. 6) The third protective layer is made of C (carbon), SiC, or SiOx.
The optical recording medium according to 4), which comprises a mixture.
body. 7) Oxygen in the third protective layer is 1 to 20 atomic%.
7. The optical recording medium as described in any of 4) to 6) above. 8) The thickness of the second protective layer is D2, and the thickness of the third protective layer is D.
When M and the thickness of the light reflection layer are DR, 0.1 ≦ DM /
When D2 ≦ 0.5 and 0.01 ≦ DM / DR ≦ 0.1
The optical recording according to any one of 1) to 7), wherein
Recording medium. 9) 0.15 ≦ DM / D2 ≦ 0.35 and 0.0
8) characterized in that 3 ≦ DM / DR ≦ 0.05
The optical recording medium described. 10) The third protective layer has an average electronegativity of En (av
e), the molar concentration (%) of the constituent element is mi, and the constituent element is
When the electronegativity of is Eni, En (ave) = (Σmi × Eni) /100≦2.3 1) to 9), characterized by comprising an amorphous substance
The optical recording medium according to any one of 1. 11) Resin protective layer and / or adhesive layer on the light reflection layer
Lath transition temperature is 90 to 180 ° C.
The optical recording medium according to any one of 1) to 10). 12) The glass transition temperature is 100 to 165 ° C.
11. An optical recording medium according to 11) above. 13) Having a resin protective layer and an adhesive layer on the light reflection layer,
The difference in the glass transition temperature of the layers is 50 ° C or less.
The optical recording medium according to any one of 1) to 12). 14) Difference in glass transition temperature is 30 ° C or less
13. The optical recording medium as described in 13) above. 15) The light reflection layer is different from Ag in Al, Bi, Ca,
Cu, Cd, Fe, Mn, Mg, Ni, Pd, Pb, S
At least one element selected from b, Zn, and Nd is added.
What is described in 1) to 14), characterized by being made of added materials
An optical recording medium described therein. 16) The elements added to Ag are Cu and Nd.
15. The optical recording medium as described in 15) above. 17) The width of the guide groove formed on the substrate is 0.10 to 0.
DVD-ROM with 40 μm and depth of 15-45 nm
It is a rewritable optical recording medium that can be replaced.
The optical recording medium according to any one of 1) to 16). 18) The width of the guide groove is 0.15 to 0.35 μm, and the depth is
The light according to 17), which has a wavelength of 20 to 40 nm.
recoding media. 19) The width of the guide groove formed on the substrate is 0.25 to 0.
65 μm, depth 20-50 nm (for CD-RW media)
In any one of 1) to 18),
Optical recording medium. 20) The width of the guide groove is 0.30 to 0.60 μm, and the depth is
The light according to 19), which has a wavelength of 25 to 45 nm.
recoding media. 21) Film-forming speed of the third protective layer is Rm, film-forming of the light-reflecting layer
When the velocity is Rr, both layers are 0.02 ≦ Rm / Rr ≦ 0.20 0.5 nm / sec ≦ Rm ≦ 5.0 nm / sec It is characterized that it is a film formed under the condition
The optical recording medium according to any one of 1) to 20). 22) Sputter deposition power of the third protective layer is Pm, light reflection
When the sputtering film forming power of the layers is Pr, both layers are 1.5 × Pm ≦ Pr It is characterized that it is a film formed under the condition
The optical recording medium according to any one of 1) to 20). 23) Film-forming speed of the third protective layer is Rm, film-forming of the light-reflecting layer
When the velocity is Rr, both layers are 0.02 ≦ Rm / Rr ≦ 0.20 0.5 nm / sec ≦ Rm ≦ 5.0 nm / sec 1) to 20) characterized in that a film is formed under the following conditions
A method for manufacturing an optical recording medium according to any one of 1. 24) Sputter deposition power of the third protective layer is Pm, light reflection
When the sputter deposition power of the layers is Pr, both layers are 1.5 × Pm ≦ Pr 1) to 20) characterized in that a film is formed under the following conditions
A method for manufacturing an optical recording medium according to any one of 1. 25) The third protective layer is a mixture of SiC and SiOx.
It is a special feature that the film is formed by sputtering using a get.
Production of the optical recording medium according to any one of 4) to 20)
Build method. 26) The third protective layer is a SiC target and Ar.
And O_Two, CO, CO _TwoAt least one selected from
Film formation by reactive sputtering using mixed gas of
The optical recording according to any one of 4) to 20), characterized in that
Recording medium manufacturing method.

The present invention will be described in detail below. An example of the mode of the present invention is shown in FIGS. The basic structure is such that the first protective layer 2, the optical recording layer 3, the second protective layer 4, the third protective layer 5, the light reflecting layer 6 are formed on the substrate 1 having the guide groove.
A hard coat having a resin protective layer (overcoat layer) 7 for the purpose of forming a printing layer 10 on the surface and improving scratch resistance on the reproduction light incident surface (substrate mirror surface), if necessary. You may form a layer. Further, in the case of a DVD type optical recording medium, it may have a bonding structure with an adhesive layer 8 interposed therebetween. The disc on the other side to be attached is
The same single plate disk or only the cover substrate (transparent substrate) 9 may be used. Alternatively, the printing layer may be formed on the opposite surface side after laminating the single plate disk without forming the printing layer. Further, the resin protective layer and the adhesive layer may be combined to form one layer.

The material of the substrate is usually glass, ceramics or resin, and a resin substrate is preferable in terms of moldability and cost. Examples of such resins include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin,
Fluorine-based resins, ABS resins, urethane resins and the like can be mentioned, but polycarbonate resins and acrylic resins which are excellent in moldability, optical characteristics and cost are preferable. However, when the optical recording medium of the present invention is applied to a rewritable optical recording medium which is compatible with DVD-ROM, it is desirable that the following specific conditions are given. That is, the width of the guide groove formed on the substrate to be used is 0.10 to 0.40 μm,
Preferably, the depth of the guide groove is 0.15 to 0.35 μm and is 15
It is about 45 nm, preferably 20 to 40 nm. With such a substrate groove, reproduction compatibility in a DVD-ROM drive is improved. The thickness of the substrate is 0.5
5 to 0.65 mm is suitable, and the thickness of the disc after lamination is preferably 1.1 to 1.3 mm. Also,
When the optical recording medium of the present invention is applied to a CD-RW medium, the width of the guide groove is 0.25 to 0.65 μm, preferably 0.30 to 0.60 μm, and the depth of the guide groove is 20 to. 50n
m, preferably 25 to 45 nm.

The materials for the first protective layer and the second protective layer are ZnS.SiO ₂ (15 mol%) and ZnS.SiO.
₂ (20 mol%), ZnS.SiO ₂ (25 mol%) and other substances containing ZnS and SiO ₂ are effective. In addition, SiO, SiO ₂ , ZnO, SnO ₂ , Al _{2
O 3, TiO 2, In 2} O 3, MgO, oxides such as _{ZrO 2; Si 3 N 4,} AlN, TiN, BN, nitrides such as ZrN; ZnS, sulfides such as TaS _4; SiC,
Carbides such as TaC, B ₄ C, WC, TiC, ZrC;
Diamond-like carbon or a mixture thereof can also be used. In particular, ZnS.SiO, which is located above and below the phase-change optical recording layer, has optimized optical constants, coefficients of thermal expansion, and elastic modulus as protective layers that are subject to thermal expansion changes and thermal damage due to changes in high temperature and room temperature. ₂ (20 mol%) is desirable. The film thickness of the first protective layer has a great influence on the reflectance, the degree of modulation, and the recording sensitivity. Therefore, it is preferable to set the film thickness to 60 to 120 nm in order to obtain good signal characteristics. The thickness of the second protective layer is 5 to 45 nm, preferably 7 to 40 nm. When the thickness is less than 5 nm, the function as the heat resistant protective layer is not fulfilled and the recording sensitivity is lowered. On the other hand, when the thickness is more than 45 nm, interfacial peeling is likely to occur and the repetitive recording performance also deteriorates.

The optical recording layer contains SbTe capable of undergoing a phase change between a crystal-amorphous phase and being in a stable or metastable state, and its composition ratio is S.
The phase change type optical recording material of b _χ Te _100-χ (χ is atomic%, 40 ≦ χ ≦ 80) has a recording (amorphization) sensitivity / speed, an erasing (crystallization) sensitivity / speed, and an erasing ratio. Suitable because it is good. Further, the phase change type optical recording layer is required not only for recording and erasing, but also for the reproduction stability of signals and the service life (reliability) of signals when recorded in a high density and high linear velocity region. GeSbTe, AgInSbTe, GeInSbTe containing SbTe as a main component are used as a phase-change optical recording layer that can satisfy these requirements.
Etc. have been commercialized.

However, in order to record at a high speed of 10 m / sec or more, the composition formula is (Ag and / or Ge) α (I
n and / or Ga and / or Bi) βSbγTeδMε
(In the formula, M is an additive element, α, β, γ, δ, ε are atomic%,
As α + β + γ + δ + ε = 100), a phase change type optical recording material satisfying the following conditions is excellent. 0.1 ≦ α ≦ 10 1 ≦ β ≦ 15 60 ≦ γ ≦ 90 15 ≦ δ ≦ 30 0 ≦ ε ≦ 10 In the composition region satisfying these conditions, 10 m / sec
The above high-speed recording / erasing is possible, and CAV (constant angular velocity) recording with different recording speeds of 2.4 times on the inner circumference and the outer circumference is possible. As the additive element M, it is effective to add a metal whose thermal conductivity is smaller than that of the metal Sb to reduce the recording power, which is a problem during high speed recording. Specific examples of such metals include Sc, Y, La, Ce, Pr,
Examples thereof include lanthanum series metals such as Nd, Sm, Eu, Gd, Tb, Dy, and Ho, and Ti, Zr, and Mn. The addition amount of the additional element M is preferably 10 atomic% or less. When it exceeds 10 atomic%, the recording and erasing characteristics are affected and the overwrite performance becomes insufficient.

A cubic lattice crystal structure in which the crystal structure in the unrecorded state after initialization is an isotropic crystal structure, preferably NaC
A material having an l-type crystal structure can undergo a phase change with less variation from an amorphous phase, which is also considered to have high isotropy, and performs recording (amorphization) and erasing (crystallization) at high speed and uniformly. Suitable because it can. The thickness of the phase change type optical recording layer is 10 to 50.
nm, preferably 12 to 30 nm. Further, considering initial characteristics such as jitter, overwrite characteristics, and mass production efficiency, the thickness is preferably 13 to 25 nm.
When the thickness is less than 10 nm, the light absorption ability is remarkably lowered and the role cannot be fulfilled. If it is thicker than 50 nm, it is difficult for a uniform phase change to occur at high speed. Such an optical recording layer can be formed by various vapor phase growth methods such as a vacuum vapor deposition method, a sputtering method, a plasma CVD method, an optical CVD method, an ion plating method and an electron beam vapor deposition method. Among them, the sputtering method is preferable because it is excellent in mass productivity and film quality.

As a result of extensive studies on the above-mentioned problems of the Ag-based light reflecting layer, in order to secure the light reflectance and the high thermal conductivity which are the characteristics of Ag as the light reflecting layer of the optical recording medium,
It was necessary to use Ag with a purity of 95% by weight or more. However, the high-purity Ag-based light reflecting layer having a purity of 95% by weight or more does not have sufficient high temperature and high humidity storage reliability, and film peeling or corrosion of the Ag-based light reflecting layer occurred. Therefore, as a result of studying the mechanism of film peeling and corrosion, it was found that the sulfur source and chlorine source in the resin protective layer and / or the adhesive layer on the Ag-based light reflecting layer were moisture (H
In contact with Ag in the presence of _{2 O),} it revealed that corrode Ag. It has been found that the corrosion progresses when the sulfur source and the chlorine source reaching the Ag surface infiltrate through the Ag grain boundaries through water as a medium. As a countermeasure, A, which has excellent compatibility with Ag, is used.
l, Bi, Ca, Cu, Cd, Fe, Mn, Mg, N
It is effective to add at least one element selected from i, Pd, Pb, Sb, Zn and Nd, and in particular,
It is preferable to add Cu and Nd. These additional elements have the effect of preventing oxidation and suppressing the generation of voids associated with Ag particle aggregation.

However, recent demands for reliability are strong, and it is particularly required to secure reliability under a high temperature environment. For example, in vehicle use of car navigation systems and the like, high temperature reliability of about 70 ° C. is expected in consideration of the summer environment. By alloying Ag as described above, A
Although the reliability of the g reflective layer can be improved, the reliability in an environment of 70 ° C. or higher was not sufficient. The environmental temperature of 70 ° C. indicates that the optical disk surface inside the actual optical disk reproducing or recording apparatus is 85 to 90 ° C. Therefore, it is required to secure reliability at a temperature of the optical disc of 80 to 90 ° C. Further, since the cost is increased by using the alloy, it is desired to develop a better countermeasure.

As described above, film peeling and corrosion of the Ag-based light reflecting layer are strongly affected by moisture, so that the reliability of the Ag-based light reflecting layer is considered to be impaired by the electrochemical action. Therefore, it is presumed that the Ag-based light reflection layer is deteriorated due to the electric bias, polarization, and ionization of Ag atoms. Based on such knowledge, the present inventors have the following (1) to (3) in order to improve the reliability of the Ag reflective layer.
Thought that was important. (1) Suppression of contact with moisture (2) Formation of Ag on the underlayer which is difficult to polarize and ionize (3) Aiming to improve the adhesion with the underlayer by a physical method rather than chemical bonding Therefore, the following (a)-(b) was examined as a countermeasure. (A) Resin protective layer and / or adhesive layer that suppresses moisture permeation to the Ag-based light reflection layer (b) Third protective layer (surface modified layer) that is optimal for the Ag-based light reflection layer

First, the resin protective layer and / or the adhesive layer (a) for suppressing moisture permeation to the Ag light reflecting layer will be described. As a result of diligent studies on the causes of corrosion and film peeling of the Ag reflective layer under high temperature and high humidity, it was found that it depends on the glass transition temperature of the resin protective layer and / or the adhesive layer coating the Ag-based light reflective layer. . That is, the water permeability and the coefficient of linear expansion of the resin protective layer and / or the adhesive layer remarkably increase at a glass transition temperature or higher. As a result, it was found that the optical recording medium is deteriorated by promoting the arrival of water on the Ag surface, which is a main factor of corrosion of the Ag reflective layer and film peeling. Therefore, in order to secure the reliability of the Ag reflective layer up to a disk temperature of 90 ° C., a general reliability test of 80 ° C. 85%
Considering RH, it is effective to set the glass transition temperature of the resin protective layer and / or the adhesive layer to 90 ° C. or higher. Further, a resin protective layer and / or an adhesive layer having a glass transition temperature of 100 ° C. or higher that theoretically maximizes the water permeation rate is desirable. However, when the glass transition temperature of the resin protective layer and / or the adhesive layer is too high, the bending strength of the optical recording medium becomes small, and the optical recording medium is easily broken when dropped on the floor or taken out from the plastic case. Cause Therefore, in order to make the optical recording medium hard to break, it is desirable that the glass transition temperature of the resin protective layer and / or the adhesive layer is 180 ° C. or lower, preferably 165 ° C. or lower.

When the resin protective layer and the adhesive layer are adjacent to each other on the Ag reflection layer, the thermal expansion coefficient and the like greatly differ when the difference in glass transition temperature between the two layers becomes large. As a result, the optical recording medium is deformed, warped, and tilted, particularly, circumferentially deformed, warped, and tilted.
An error is likely to occur during reproduction and recording at a high speed of at least / sec. Therefore, in order to realize stable reproduction and recording at a high speed of 10 m / sec or more, the difference in glass transition temperature between the resin protective layer and the adhesive layer on the Ag reflective layer should be 50 ° C.
It is necessary to reduce the temperature to the following level, preferably 30 ° C. or lower. As a concrete measure, it is also effective to use the same material for the resin protective layer and the adhesive layer. The glass transition temperature (Tg) is defined as the temperature at which the specific volume, the specific heat, the refractive index, the dielectric constant, the diffusion constant, the elastic modulus, etc. suddenly changes when the resin changes due to a temperature rise. The glass transition temperature of the resin is controlled by the intermolecular force resulting from the chemical structure of the starting monomer of the polymer compound constituting the resin, the size of the substituent, the polarity and the like. This glass transition temperature can be measured from the inflection point of tan δ with a viscoelasticity measuring device.

The thickness of the Ag-based light reflecting layer is 50 to 2
The thickness is preferably 00 nm, preferably 70 to 160 nm.
It is also possible to make the Ag-based light reflection layer multi-layered.
When multi-layered, the thickness of each layer is at least 10 nm
If necessary, the total film thickness of the multi-layered film should be 50 to 160 nm. When used as a semitransparent reflective layer of a multilayer recording layer, 10 to 50 nm is suitable. The Ag-based light reflection layer can be formed by various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating and electron beam evaporation.
However, sputtering is desirable as a method of manufacturing an optical recording medium.

A resin protective layer (overcoat layer) is formed on the reflective layer to prevent its oxidation. As the resin protective layer, an ultraviolet curable resin layer produced by spin coating is suitable. The thickness is suitably 3 to 15 μm, and if it is thinner than 3 μm, an increase in errors may be observed when the printing layer is provided on the resin protective layer and the overcoat layer. On the other hand, if thicker than 15 μm,
The internal stress becomes large, which greatly affects the mechanical properties of the disk.

Also in the case of providing the hard coat layer, an ultraviolet curable resin produced by a spin coat method is generally used. The appropriate thickness is 2 to 6 μm. If the thickness is less than 2 μm, sufficient scratch resistance cannot be obtained. If it is thicker than 6 μm, the internal stress becomes large and the mechanical properties of the disk are greatly affected. Further, the hardness thereof needs to be equal to or higher than the pencil hardness H, which does not cause a large scratch even if it is rubbed with a cloth. It is also effective to mix an electrically conductive material as necessary to prevent static electricity and prevent adhesion of dust and the like.

The printing layer is for the purpose of ensuring scratch resistance, label printing of brand names, etc., formation of an ink receiving layer for an ink jet printer, etc., and it is preferable to form an ultraviolet curable resin by a screen printing method. is there.
A suitable thickness is 3 to 50 μm. If the thickness is less than 3 μm, unevenness may occur during layer formation, and 50 μm
If the thickness is made thicker, the internal stress becomes larger and the mechanical properties of the disk are greatly affected.

For the adhesive layer, an adhesive such as an ultraviolet curable resin, a hot melt adhesive or a silicone resin can be used. The material of such an adhesive layer is applied onto the overcoat layer or the printing layer by a method such as spin coating, roll coating or screen printing depending on the material,
After performing treatments such as UV irradiation, heating, pressurization, etc., the discs on the opposite side are bonded together. The disk on the opposite surface may be the same single plate disk or only a transparent substrate, and the bonding surface of the disk on the opposite surface may or may not be coated with the material of the adhesive layer. A pressure-sensitive adhesive sheet can also be used as the adhesive layer. The film thickness of the adhesive layer is not particularly limited, but is 5 to 100 μm, and preferably 7 to 80 μm, in consideration of the applicability and curability of the material and the mechanical properties of the disk. The range of the adhesive surface is not particularly limited, but when it is applied to a rewritable disc compatible with DVD and / or CD, it is necessary to secure the adhesive strength in order to enable high-speed recording. It is desirable that the position of the peripheral edge is Φ15 to 40 mm, preferably Φ15 to 30 mm.

Next, the optimum third protective layer (surface modified layer) for the Ag-based light reflecting layer of (b) will be described. Conventional Ag
The system light reflection layer has been formed on ZnS.SiO ₂ .
However, since ZnS / SiO ₂ contains Zn and S, its surface is electrochemically active. Microscopically, SiO ₂ has a positive polarization of Si and a negative polarization of O, has good wettability with water and easily retains water, and is required to form an Ag-based light reflection layer. Not suitable. Therefore, the inventors of the present invention have found that a layer having a problem in surface physical properties, such as the ZnS.SiO ₂ layer, is present between the Ag-based light-reflecting layer and the second protective layer due to the relationship with the Ag-based light-reflecting layer. It was considered to form a third protective layer (surface modified layer) for changing the surface condition. As the characteristics required for the third protective layer, the materials and manufacturing conditions were examined in consideration of the following points (1) to (4). (1) Use a non-metal that has a small electrochemical action with Ag (2) Use a constituent element that has a lower electronegativity than Ag to prevent ionization of Ag (3) Physical surface modification (4) Adopt an amorphous material to prevent water and impurities from moving through grain boundaries.

As a result of examination, Si having the following physical properties (i) and (ii) was extracted as an element satisfying the above conditions. (I) Si is a non-metal (semi-metal) and its electronegativity is 1.8, which is smaller than the electronegativity of Ag of 1.9. (Ii) The bond energy of Si-Si is 76 kcal.
(Kcal / mol), 104 kc of Si-C bond
al / mol, 192 kcal / mol of Si—O bond, C
Small compared to 144 kcal / mol of -C bond. Next, the present inventors produced a DVD + RW compatible optical recording medium having a layer structure as shown in FIG. 1 having various third protective layers based on Si, and the temperature rising / lowering rate was 10 ° C./hour. ℃ 95% RH12 hours and 40 ℃ 95% RH12
Six heat cycle tests were conducted under the condition of time. The sample medium has a guide groove and a thickness of 0.6 mm.
8 as a first protective layer on the polycarbonate substrate of
ZnS.SiO ₂ (20 mol%) of 0 nm, and Ga ₃ Ge ₃ Mn ₃ Sb ₇₁ Te having a film thickness of 15 nm as an optical recording layer.
₂₀ , ZnS.SiO having a film thickness of 15 nm as the second protective layer
₂ (20 mol%), a film made of the material of Table 1 below having a film thickness of 5 nm as the third protective layer, and a film thickness of 140 nm as the light reflecting layer.
99.99% by weight of Ag was sequentially provided by sputtering, and then a resin protective layer having a Tg of 130 ° C. was provided, and then a cover substrate was further bonded with an adhesive having a Tg of 135 ° C.

[0029]

[Table 1]

Table 1 above shows (1) the elements of the third protective layer.
Molar concentration (%), (2) Chemical bond in third protective layer material
Bond number order by compound type (type of bond between elements) and each
The binding energy (kcal / mol) of the chemical bond species,
(3) Structure of the third protective layer, (4) Average electricity of the third protective layer
Negativity, (5) DVD + RW medium using the third protective layer
The defect rate after the heat cycle test of the body is shown. In addition,
3 Whether the structure of the protective layer is crystalline or amorphous
Is an amorph if the halo pattern is seen by electron diffraction.
It was determined to be a In addition, "defect rate" is unrecorded
Do not irradiate the laser beam on the recordable area of the
When scanning the guide groove, the length of the scanned groove is
The part where the reflectance deviates from the predetermined reflectance standard value
Say the length ratio. Furthermore, in the defect rate column, for example, “7.
"7E-05" means "7.7 x 10". ^-5By
is there.

D using a third protective layer containing various Si
The relationship between the defect rate of the VD + RW medium after the heat cycle test and the Si content of the third protective layer material and the average electronegativity are shown in FIGS. 3 and 4. From FIGS. 3 and 4, 1.0E-05 (= 1.0 × 1), which is the defect rate that can ensure reliability.
0 ^-5) in order to ensure the third molar concentration of Si in the protective layer material 35% or more, it can be seen that better to the average electronegativity than 2.3. The average electronegativity referred to here is the electronegativity of the constituent elements averaged according to the proportion of each element present, and the average electronegativity of the third protective layer is En (ave). , Molar concentration of constituent elements (%)
Is mi and the electronegativity of the constituent elements is Eni,
It is defined by the following formula. En (ave) = Σmi · Eni This lower limit of the average electronegativity is not particularly limited in terms of whether or not the effect of the present invention is exerted, but in practice, Experiment 1 of Table 1
1. In the case of Ti and Ta which are simple metals as seen in Nos. 5 and 18, 1.
5th place is considered to be the limit value. The average electronegativity expresses the polarization state of Ag and the third protective layer. If this polarization is large, water (H ₂ O) enters the interface,
It is considered that the film floating of Ag and the third protective layer is promoted.

The third protective layer needs to contain Si as described above, and in order to ensure the reliability of the Ag-based light reflecting layer, it must contain Si in an amount of 35 atomic% or more. Further, it is effective to increase the molar concentration of Si. However, since the third protective layer must be matched with the underlying second protective layer from the viewpoint of the coefficient of thermal expansion, elastic modulus, chemical reactivity, etc., depending on the material of the second protective layer,
It is also effective to add C, O, N or the like to Si.
Even in the third protective layer, which is a film thinner than the other layers, the influence of the optical characteristics on the medium characteristics cannot be ignored. Si
Is good from the viewpoint of reliability, but it has some spectral absorption ability, and if it is made too thick, there is no point in providing an Ag-based light reflecting layer in order to obtain high reflectance.

When the second protective layer is made of ZnS.SiO ₂ (20 mol%), the material of the third protective layer is Si,
A material consisting of Si, C (carbon) and O (oxygen) obtained by adding O to SiC or SiC is effective, and in particular, a mixture of SiOx containing SiC as a main component or C containing C as a main component (carbon). ) And SiOx are preferred. S
Since iC has a characteristic that it has an extremely high melting point, is thermally stable, and is dense, it is possible to suppress the reaction between sulfur contained in the second dielectric layer and Ag of the reflective layer even if the film thickness is made thin. Although it has excellent properties, it has a drawback that the adhesion is poor because it has high hardness and does not react with Ag. On the other hand, when a material made of Si, C (carbon) and O (oxygen) is used for the third protective layer as in the present invention, the adhesion is remarkably improved and the corrosion is remarkably reduced.

The thickness of the third protective layer is set to a thickness that does not significantly affect the high reflectance and high thermal conductivity expected of the Ag-based light reflecting layer. In addition, the expected recording of the second protective layer
It is set so that there is no adverse effect on the flexible function against thermal deformation at the time of erasing, the control function of recording sensitivity, and the control function of the initialized state by the large-diameter LD for crystallizing the amorphous layer of the recording layer. In consideration of these points, the inventors of the present invention have considered that the film thickness DM of the third protective layer is set in the range of 2 to 9 nm to effectively maintain the signal characteristics of recording and erasing, and to reduce Ag-based light. It was found that the reliability of the reflective layer can be secured. If the thickness is 2 nm or more, reproducibility of repeated film formation during continuous mass production and in-plane uniformity can be guaranteed, and the function of surface modification is exhibited. It is preferably 3 to 7 nm, and within this range,
The reliability of the Ag-based light reflecting layer can be greatly improved without significantly changing the basic optical design and thermal design of the optical recording medium.

Specifically, DVD + at 14 m / sec
The jitter after 1000 times of overwriting by the RW format is good at 8% or less. On the other hand, when the thickness exceeds 9 nm, the surface-modified layer is more preferable than JP-A-11-2382.
The film thickness of the intermediate layer as disclosed in JP-A-53-53 and JP-A-2000-331378 not only modifies the surface but also the physical properties of the intermediate layer affect the characteristics of the optical recording medium. Since it will be an area, it will be necessary to drastically change the optical design and thermal design. It was also found that the internal stress is generated in the third protective layer (surface modified layer) itself, and the third protective layer is destroyed by cracks or the like in the heat cycle.

Further, when the film thickness of the second protective layer is D2, the film thickness of the third protective layer is DM, and the film thickness of the light reflecting layer is DR, it is more effective if the following conditions are satisfied. It was also found that the signal characteristics of recording / erasing can be maintained and the reliability of the Ag-based light reflecting layer can be secured. 0.1 ≦ DM / D2 ≦ 0.5 and 0.01 ≦ DM / DR ≦ 0.1 Further, if the above conditions are set within the following range, 14 m / sec
Overwrite 1 in DVD + RW format at
It was also found that the jitter after 000 times was as good as 8% or less. 0.15 ≦ DM / D2 ≦ 0.35 and 0.03 ≦ DM / DR ≦ 0.05

As the method for producing the third protective layer, sputtering, plasma CVD, plasma treatment, ion plating, photo CVD, etc. can be used, but sputtering generally used in optical recording media is effective. The typical manufacturing conditions are pressure 10 ⁻² to 10 ⁻⁴ P.
a, sputtering power 0.5 to 5.0 kW / 200 mmφ,
The film forming rate is 0.5 to 5.0 nm / sec. What is important here is that 0.02 ≦ Rm / Rr ≦ 0.20 0.5 nm / sec ≦ Rm ≦, where Rm is the film formation rate of the third protective layer and Rr is the film formation rate of the light reflection layer. It is to be 5.0 nm / sec. Further, in order to form a film composed of Si, C (carbon) and O (oxygen), SiC and SiOx are used.
Using a mixture target of Si or Si
Reactive sputtering using a C target and a mixed gas of Ar and at least one selected from O ₂ , CO, and CO ₂ is particularly effective. Then, for example, when a mixed gas of Ar and CO ₂ is used, as shown in Table 1, the oxygen content in the third dielectric layer can be controlled by changing the flow rate ratio of Ar and CO _2. it can.

This is because the frequency of incidence of Ag when forming the Ag-based light-reflecting layer formed thereon is 5 to 50 times as high as the frequency of incidence of atoms forming the third protective layer into the film. By increasing the temperature, the outermost surface temperature of the third protective layer becomes high, and the weakly bonded portion of the third protective layer disappears.
The g atom enters the third protective layer, and when the third protective layer is cooled, the Ag atom remains in a wedge-like state to improve the film adhesion between the Ag-based light reflecting film and the third protective layer. This is because it can be done. The film forming rate of the third protective layer is 0.5 to 5.
0 nm / sec is desirable. If it is 0.5 nm / sec or more, the gas is less taken into the third protective layer to form a dense film, and if it is 5 nm / sec or less, the disc-to-disk variation in the film thickness is small, and a thin film of 9 nm or less is formed. It is possible to manufacture with good reproducibility.

Further, the sputtering film forming power of the third protective layer is set to P
m and the sputtering film forming power of the light reflection layer is Pr, by setting 1.5 × Pm ≦ Pr, the Ag-based light reflection is also performed for the same reason as when the above film forming speed condition is satisfied. The film adhesion between the film and the third protective layer can be improved. In this case, not only the surface temperature of the third protective layer becomes high, but also Ag
Since the sputtering power at the time of forming the system light reflection layer is 1.5 times or more, the frequency of incidence of ions having high energy also increases, so that the weakly bonded portion of the third protective layer can be effectively removed. It is possible to improve the adhesion with the Ag-based light reflection layer. Sputtering film forming power P of the light reflecting layer
The upper limit of r is the upper limit of the equipment specifications of the sputtering apparatus. That is, the upper limit of the electric power that enables stable sputtering as an apparatus is about 10 kW in reality.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

Example 1 A polycarbonate substrate having a thickness of 0.6 mm having a groove width of 0.25 μm, a groove depth of 27 nm, and a guide groove having a wobble groove period of 4.26 μm was injection molded, and a first protective film was formed on this substrate. Layer, optical recording layer, second protective layer, third protective layer, and purity 9
Ag light reflecting layers of 9.99% by weight were sequentially laminated by a sputtering method. ZnS is used for the first protective layer and the second protective layer.
· _SiO 2 using (20 mol%), respectively, thickness 80
nm and 14 nm. Ga ₃ Ge ₃ Mn is used for the optical recording layer.
₄ Sb ₇₀ Te ₂₀ was used and the thickness was set to 16 nm. Third
A Si film with a thickness of 4 nm was used for the protective layer. The electronegativity of Si was 1.8, and a material smaller than the electronegativity of 1.9 of Ag was selected. The Ag light reflection layer has a thickness of 140 nm
And The film forming speeds of the first protective layer, the optical recording layer, the second protective layer, the third protective layer, and the Ag light reflecting layer were each 9 nm / se.
c, 5.6 nm / sec, 4.5 nm / sec, 1.5
nm / sec, 32 nm / sec, and film forming sputtering powers of 4 kW, 0.4 kW, and 1.5 kW, respectively.
It was set to 1.5 kW and 3.5 kW. As a result, the polycarbonate substrate / ZnS.SiO ₂ (80 nm) / Ga ₃
Ge ₃ Mn ₄ Sb ₇₀ Te ₂₀ (16 nm) / ZnS
A laminated structure of SiO ₂ (14 nm) / Si (4 nm) /99.99 wt% Ag (140 nm) was formed. Then, an ultraviolet curable resin having a room temperature viscosity of 120 cps and a glass transition temperature after curing of 149 ° C. was spin-coated on the Ag light reflection layer to form a resin protective layer, and a single-disc disk of a phase-change optical recording medium was formed. Created. Then, the bonded substrate made of polycarbonate was bonded with an ultraviolet-curing adhesive having a room temperature viscosity of 580 cps and a glass transition temperature of 135 ° C. after curing to obtain an optical recording medium having a DVD type structure as shown in FIG. .

Next, a large-diameter LD (beam diameter 200 × 1 μ
m laser diode), linear velocity 3.5 m / sec, power (LD power) 85
At 0 mW and a feed of 120 μm, the entire surface was crystallized from the inner circumference to the outer circumference at a constant linear velocity. Subsequently, a recording linear velocity of 16.75 m / sec, a wavelength of 650 nm, an NA of 0.65, and a recording power of 14.5 mW were applied to the obtained phase change optical recording medium.
Then, optical recording was performed in a DVD-ROM reproducible format. As a result, direct overwrite (DOW)
Data to Clock Ji after recording 1000 times
The tter (data to clock jitter) was as good as 7.5%. In addition, the reflectance was 20% and the degree of modulation was 63%, and the signal characteristics were also good, and the original high light reflectance and high thermal conductivity of Ag could be efficiently utilized. Furthermore, with respect to this optical recording medium, at a temperature ascending / descending speed of 10 ° C./hour, 2
A heat cycle test was performed 6 times under the conditions of 5 ° C. 95% RH for 12 hours and 40 ° C. 95% RH for 12 hours. As a result, the reflectance was 20%, the degree of modulation was 63%, and the tilt of the outer circumference was 58 mm was 0.4 °.
No change was observed. Further, no increase in defect rate was observed.

Examples 2 to 13 A 0.6 mm thick polycarbonate substrate having guide grooves with a groove width of 0.25 μm, a groove depth of 27 nm, and a wobble groove period of 4.26 μm was injection-molded, and a first substrate was formed on this substrate. 1 protective layer, optical recording layer, 2nd protective layer, 3rd protective layer, and purity 9
Ag light reflecting layers of 9.99% by weight were sequentially laminated by a sputtering method. ZnS is used for the first protective layer and the second protective layer.
· _SiO 2 using (20 mol%), the optical recording layer is Ga ₃
Ge ₃ Mn ₄ Sb ₇₀ Te ₂₀ was used, and the materials shown in Table 2 below were used for the third protective layer. Table 2 shows the film thickness of each layer and the manufacturing conditions at this time. Then, a room temperature viscosity of 120 cps and a glass transition temperature after curing of 1 on the Ag light reflecting layer.
An ultraviolet-curable resin having a temperature of 49 ° C. was spin-coated to form an environmental protection layer, and a single plate disk of a phase change optical recording medium was prepared. Then, the bonded substrate made of polycarbonate was bonded with an ultraviolet-curing adhesive having a room temperature viscosity of 580 cps and a glass transition temperature of 135 ° C. after curing to obtain an optical recording medium having a DVD type structure as shown in FIG. .

Next, a large-diameter LD (beam diameter 200 × 1 μm
Laser diode) of the
Linear velocity 3.5m / sec, power (LD power) 850m
With W and a feed of 120 μm, the entire surface was crystallized from the inner circumference to the outer circumference at a constant linear velocity. Next, a recording linear velocity of 16.75 m / sec and a wavelength of 650 were applied to the obtained phase change optical recording medium.
nm, NA 0.65, recording power 14.5 mW, DV
Optical recording was performed in a D-ROM reproducible format. As a result, with the third protective layer thickness of 2 to 9 nm, the jitter after DOW 1000 times was 9% or less, which was good. Furthermore, 3 to 7n
For m, the jitter after DOW 1000 times was 8% or less, which was more favorable. In addition, the reflectance was 20% and the degree of modulation was 63%, and the signal characteristics were also good, and the original high light reflectance and high thermal conductivity of Ag could be efficiently utilized. Further, this optical recording medium was subjected to a storage test at 80 ° C. and 85% RH for 500 hours, and a heat cycle test at 25 ° C. and 95% RH for 12 hours and 40 ° C. and 95% RH for 12 hours at a temperature rising / lowering rate of 10 ° C./hour. As a result of the test, as shown in Table 2 below, neither increase in defect rate nor remarkable increase in error was observed.

Comparative Examples 1 to 7 Optical recording media were prepared and carried out in the same manner as in Examples 2 to 13 except that the material and film thickness of the third protective layer were changed to those shown in Table 2 below. The test was conducted in the same manner as in Examples 2 to 13. The results are shown in Table 2. As you can see from Table 2,
Comparative Example 1 is an example in which the third protective layer is not provided, and in Comparative Examples 2 to 7, the material of the third protective layer satisfies the requirements of the present invention (containing 35 mol% or more of Si atoms), Film thickness is 1n
m or 10 nm, which is outside the range of the present invention of 2 to 9 nm. Therefore, in all cases, at least one of the jitter after DOW 1000 times, the jitter after storage for 500 hours, and the jitter after cycling was problematic, and only NG was obtained as a comprehensive judgment.

[0046]

[Table 2]

Examples 14 to 18 and Comparative Examples 8 to 10 A polycarbonate substrate having a groove width of 0.25 μm and a guide groove having a groove depth of 27 nm and a thickness of 0.6 mm was injection molded, and the first protective film was formed on the substrate. The layer, the recording layer, the second protective layer, the third protective layer, and the Ag light reflecting layer having a purity of 99.99% by weight were sequentially laminated by the sputtering method. First protective layer and second
ZnS.SiO ₂ (20 mol%) was used for the protective layer, and the film thickness was set to 80 nm and 14 nm, respectively. G on the recording layer
e _2.0 Ag _0.5 In _5.0 Sb _68.5 Te
_24.0 was used and the thickness was set to 16 nm. As the third protective layer, a SiC target and a mixed gas having a flow rate ratio shown in Table 3 were used, and sputtering was performed under the conditions of a pressure of 0.5 Pa and a power of 1 kW to form a film having a thickness of 4 nm. The Ag light reflection layer had a thickness of 140 nm. As a result, polycarbonate substrate / ZnS.SiO ₂ (80 nm) / Ge _2.
0 Ag _0.5 In _5.0 Sb _68.5 Te _24.0 (1
6 nm) /ZnS.SiO ₂ (14 nm) / SiC (4
nm) / Ag (140 nm). Then, on the Ag light reflection layer, room temperature viscosity 120 cp
s, an ultraviolet curable resin having a glass transition temperature of 149 ° C. after curing is spin-coated to form an overcoat layer,
A single disk of a phase change type optical recording medium was manufactured. Furthermore,
A polycarbonate cover substrate was attached with an ultraviolet curable adhesive to obtain an optical recording medium having the structure shown in FIG.

Next, a large-diameter LD (beam diameter 200 × 1 μ
m), the linear velocity of 3.0 m / s
ec, power (LD power) 850 mW, feed 100 μm
Then, the entire surface was crystallized from the inner circumference to the outer circumference at a constant linear velocity. Subsequently, a recording linear velocity of 8.5 m / sec, a wavelength of 650 nm, an NA of 0.65, was added to the obtained phase change optical recording medium.
Optical recording was performed with a recording power of 14 mW in a DVD-ROM reproducible format. As a result, as shown in Table 3,
Data to ClockJite after DOW recording
The number of times r was 9% or more was when the amount of oxygen contained in the third dielectric layer was 20% or less. When the oxygen content exceeded 20%, overwriting caused cracks in the third dielectric and peeling of the reflective layer. Also, when the amount of oxygen is zero, 80 ° C 85%
Although the error increase rate [(error after storage-initial error) / initial error] after the storage test for 300 hours greatly exceeded 10%, some data could not be read, but when the oxygen content was 1 atomic% or more. The increase rate was 10% or less, and it was possible to reproduce without problems even after the storage test. Further, when the Auger depth profile (Auger electron spectroscopy depth direction analysis) of the optical recording medium of Example 17 was measured, FIG.
The above results were obtained, and it was confirmed that C (carbon) in excess of Si was incorporated in the film. The Auger depth profile is high energy (1-5k).
eV) This is a method of quantifying the composition ratio by irradiating electrons and spectrally analyzing Auger electrons having energy peculiar to the substance, which is emitted from the surface of the substance.

[0049]

[Table 3]

[0050]

According to the present invention, by utilizing the high reflectance and high thermal conductivity of the Ag-based light reflecting layer, it is possible to ionize Ag and generate voids of Ag without significantly affecting optical design and thermal design. It is possible to provide an optical recording medium that is suppressed and has improved adhesion between the Ag light reflection layer and the third protective layer and that is highly reliable even during storage at high temperature and high humidity, and a method for manufacturing the same.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a DVD type optical recording medium according to the present invention.

FIG. 2 is a diagram showing an example of a CD type optical recording medium according to the present invention.

FIG. 3 shows the heat cycle reliability of DVD + RW media,
The figure which shows Si content rate dependence of a 3rd protective layer material.

FIG. 4 shows the heat cycle reliability of DVD + RW media,
The figure which shows the average electronegativity dependence of a 3rd protective layer material.

FIG. 5 is a diagram showing a result of measuring an Auger depth profile of an optical recording medium of Example 17.

[Explanation of symbols]

1 substrate 2 First protective layer 3 Optical recording layer 4 Second protective layer 5 Third protective layer 6 Light reflection layer 7 Resin protection layer 8 Adhesive layer 9 Cover substrate 10 printing layers

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/24 561 G11B 7/24 561M C23C 14/34 C23C 14/34 R G11B 7/26 531 G11B 7 / 26 531 (72) Inventor Shinya Narumi 1-3-6 Nakamagome, Ota-ku, Tokyo, within Ricoh Co., Ltd. (72) Inventor Masaki Kato 1-3-6 Nakamagome, Ota-ku, Tokyo F, Ricoh, Inc. F Term (reference) 4K029 BA22 BA64 BB02 BD00 BD09 CA05 CA06 DB02 EA02 EA09 5D029 LA13 LA14 LB01 LB03 LB07 LB11 LC11 LC21 MA13 WB11 WB17 WC01 5D121 AA04 EE03 EE09 EE17 EE18

Claims (26)

[Claims] 1. A substrate comprising at least a first protective layer, an optical recording layer, a second protective layer, a third protective layer made of a material containing 35 mol% or more of Si atoms, and a material containing 95 wt% or more of Ag. In an optical recording medium having a light-reflecting layer in this order and further having a resin protective layer and / or an adhesive layer on the light-reflecting layer, the thickness DM of the third protective layer is in the range of 2 to 9 nm. Characteristic optical recording medium. 2. The optical recording medium according to claim 1, wherein the thickness DM of the third protective layer is in the range of 3 to 7 nm. 3. The optical recording medium according to claim 1, wherein the third protective layer is made of only Si. 4. The third protective layer comprises Si, C (carbon) and O.
The optical recording medium according to claim 1 or 2, further comprising (oxygen). 5. The optical recording medium according to claim 4, wherein the third protective layer is made of a mixture of SiC and SiOx. 6. The third protective layer is C (carbon), SiC, S
The optical recording medium according to claim 4, which is composed of a mixture of iOx. 7. The optical recording medium according to claim 4, wherein oxygen in the third protective layer is 1 to 20 atomic%. 8. When the film thickness of the second protective layer is D2, the film thickness of the third protective layer is DM, and the film thickness of the light reflecting layer is DR, 0.1 ≦ DM / D2 ≦ 0.5, and , 0.01 ≦ DM /
8. The optical recording medium according to claim 1, wherein DR ≦ 0.1. 9. The optical recording medium according to claim 8, wherein 0.15 ≦ DM / D2 ≦ 0.35 and 0.03 ≦ DM / DR ≦ 0.05. 10. The third protective layer has an average electronegativity of En.
(Ave), the molar concentration (%) of the constituent elements is mi, and the electronegativity of the constituent elements is Eni. En (ave) = (Σmi × Eni) /100≦2.3 Amorphous It consists of a substance, Claims 1-
9. The optical recording medium according to any one of 9. 11. The optical recording medium according to claim 1, wherein a glass transition temperature of the resin protective layer and / or the adhesive layer on the light reflection layer is 90 to 180 ° C. 12. The glass transition temperature is 100 to 165 ° C.
The optical recording medium according to claim 11, wherein 13. A resin protective layer and an adhesive layer are provided on the light reflecting layer, and the difference in glass transition temperature between the two layers is 50 ° C. or less, according to any one of claims 1 to 12. The optical recording medium described. 14. The optical recording medium according to claim 13, wherein the difference in glass transition temperature is 30 ° C. or less. 15. The light reflecting layer comprises Ag, Al, B
i, Ca, Cu, Cd, Fe, Mn, Mg, Ni, P
At least 1 selected from d, Pb, Sb, Zn, and Nd
The optical recording medium according to any one of claims 1 to 14, which is made of a material to which a seed element is added. 16. The optical recording medium according to claim 15, wherein the elements added to Ag are Cu and Nd. 17. The width of the guide groove formed on the substrate is 0.1.
0-0.40 μm, depth 15-45 nm (DVD-
A ROM-compatible rewritable optical recording medium), wherein the optical recording medium according to any one of claims 1 to 16. 18. The width of the guide groove is 0.15 to 0.35 μm.
18. The optical recording medium according to claim 17, wherein m and the depth are 20 to 40 nm. 19. The width of the guide groove formed on the substrate is 0.2.
5 to 0.65 μm, depth of 20 to 50 nm (CD-R
The optical recording medium according to any one of claims 1 to 18, which is a W medium). 20. The width of the guide groove is 0.30 to 0.60 μm.
20. The optical recording medium according to claim 19, wherein m and the depth are 25 to 45 nm. 21. When the film forming rate of the third protective layer is Rm and the film forming rate of the light reflecting layer is Rr, 0.02 ≦ Rm / Rr ≦ 0.20 0.5 nm / sec ≦ 21. The optical recording medium according to claim 1, wherein the optical recording medium is formed under the condition of Rm ≦ 5.0 nm / sec. 22. The sputtering deposition power of the third protective layer is set to P
m, where both layers are formed under the condition of 1.5 × Pm ≦ Pr, where Pr is the sputtering film forming power of the light reflecting layer. An optical recording medium according to item 1. 23. When the film forming rate of the third protective layer is Rm and the film forming rate of the light reflecting layer is Rr, 0.02 ≦ Rm / Rr ≦ 0.20 0.5 nm / sec ≦ for both layers. The film is formed under the condition of Rm ≦ 5.0 nm / sec.
0. The method for manufacturing an optical recording medium according to 0. 24. The sputtering film forming power of the third protective layer is set to P
m, and when the sputtering film forming power of the light reflection layer is Pr, both layers are formed under the condition of 1.5 × Pm ≦ Pr.
0. The method for manufacturing an optical recording medium according to 0. 25. The method of manufacturing an optical recording medium according to claim 4, wherein the third protective layer is formed by sputtering using a mixture target of SiC and SiOx. 26. The third protective layer is formed by reactive sputtering using a SiC target and a mixed gas of Ar and at least one selected from O ₂ , CO and CO _2. The method for manufacturing an optical recording medium according to any one of claims 4 to 20.