JP2003091867A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium which attains a high multi- speed recording and a high speed CAV recording and has high shelf reliability. SOLUTION: The optical recording medium having a lower protective layer, an optical recording layer, an upper protective layer and an optical reflection layer on a substrate is characterized in that the optical reflection layer consists of silver having film thickness D (Ag) and >=99 wt.% purity and has the relation with the thickness D (TL) of the upper protective layer expressed by the formula: 5×D (TL)<=D (Ag)<=15×D(TL), that when the composition formula of alloy to be a principal component of the optical recording layer is expressed by (Ag and/or Ge)α(In and/or Ge and/or Bi)βSbγTeδ, α, β, γ and δ (atom.%) satisfy the following relational formulae; 0.001<=α/(α+β+γ+δ)<=0.05; 0.01<=β/(α+β+γ+δ)<=0.10; 0.65<=γ/(α+β+γ+δ)<=0.85; 0.10<=δ/(α+β+γ+δ)<=0.27 and β/α>=1 (or 1.5) and that the optical recording layer has 7-12 m/s (or 14-21 m/s) upper limit linear speed of re-crystallization.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase change type optical recording medium capable of recording / reproducing and rewriting information by causing an optical change in an optical recording layer by irradiating a laser beam. In particular, CD-RW media, DVD
-CD media such as RW media and DVD + RW media or D
VD-ROM compatible high-speed multi-speed recording or high-speed C
The present invention relates to an optical recording medium capable of AV (constant angular velocity) recording.

[0002]

2. Description of the Related Art As an optical recording medium capable of recording / reproducing and erasing by irradiation of a laser beam, a magneto-optical medium, a CD-RW
Medium, DVD-RW medium, DVD + RW medium, DVD-
RAM media are being studied. In these recording media, further high density and high linear velocity are expected in order to record more information faster.
As a solution, A with high reflectance and high thermal conductivity
The adoption of u, Ag, and Cu-based light reflecting layers is under study. In particular, an Ag-based light reflection layer having the highest reflectance and thermal conductivity among metals is highly expected. When Ag is used as the light reflecting layer of an optical recording medium, the following merits are expected. a. Improved medium reflectance in a wide wavelength range. b. Increased signal amplitude due to the optical properties of Ag. c. In the case of the light reflection layer of the phase change type optical recording medium, the number of overwrites is improved by the layer structure that can be cooled more rapidly. d. In the case of the light-reflecting layer of the phase-change optical recording medium, the recording linear velocity is increased by the layer structure that can be more rapidly cooled. e. High productivity due to high sputtering efficiency. f. Reduction of thermal stress by shortening sputter film formation time (improvement of medium mechanical properties).

On the other hand, when Ag is used as a light reflecting layer of an optical recording medium, there are the following problems. a. Easily corroded under high temperature and high humidity. b. Easily corroded by sulfur and chlorine. c. The film adhesion to the base is small. d. It is a noble metal and is more expensive than Al or the like. e. Abnormal mechanical properties due to Ag film stress when using a substrate of 0.6 mm or the like. As a method for suppressing Ag corrosion, JP-A-57-186
244, AgCu described in JP-A-7-3633, AgOM (M: Sb, Pd, Pt) described in JP-A-9-156224, JP-A-20
The alloying of Ag, such as that found in AgPdCu described in JP-A-00-285517, is known. Also, patent 2
Japanese Patent No. 749080 discloses Ag, Ti, V, Fe, Co, Ni, Zn, and Ag for the purpose of controlling thermal conductivity.
Zr, Nb, Mo, Rh, Pd, Sn, Sb, Te, T
It is disclosed to contain a, W, Ir, Pt, Pb, Bi, and C.

However, these material systems are actually used as a light reflecting layer.
Used for CD-RW media, DVD-RW media, DVD +
An RW medium was manufactured and the recording signal was evaluated.
Emissivity and signal amplitude could not be obtained. This is 1w for Ag
This is a characteristic of Ag because other metals exceeding t% are added.
This is because high reflectance and high thermal conductivity cannot be obtained. Well
In addition, the archiver of these media at 80 ℃ and 85% RH
The high temperature storage reliability was evaluated, and it was stored for 300 hours.
A rapid increase of errors was recognized in
It was not possible to obtain sufficient storage reliability. Furthermore, phase change type optical recording
ZnSSi used for the upper protective layer in recording media
O _TwoThe reaction between sulfur and Ag to produce AgS is
It is considered to be one of the causes of food, and as a countermeasure for this,
In No. 11-238253, Au, Co, Cr, N
i, Pd, Si, Ta, Ta_TwoO₅, V, W, amorphous
Carbon, ZnSSiO_TwoIntermediate between protective layer and Ag reflective layer
The use in layers is disclosed. Light reflection of optical recording medium
When an Ag thin film is used as the layer, the above problems are overcome.
How to bring out the excellent thermal and optical characteristics of Ag
This is a major issue, but when using Ag for the light reflection layer
Optimization of composition of optical recording layer and thermal / optical design of each layer
Has not been sufficiently studied, and it is still being rewritten into an optical recording medium.
Has not been realized.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium capable of high speed multi-speed recording and high speed CAV recording and having high storage reliability.

[0006]

[Means for Solving the Problems] The above problems are solved in the following 1) to
This is solved by the invention 7) (hereinafter referred to as the present inventions 1 to 7). 1) In an optical recording medium having a lower protective layer, an optical recording layer, an upper protective layer, and a light reflecting layer on a substrate, the light reflecting layer is made of silver having a film thickness D (Ag) and a purity of 99 wt% or more, and an upper portion. The relationship with the film thickness D (TL) of the protective layer is 5 × D (TL) ≦ D (Ag) ≦ 15 × D (TL), and the composition formula of the alloy which is the main component of the optical recording layer is represented by ( A
g and / or Ge) α (In and / or Ga and / or Bi) βSbγTeδ, α, β, γ, δ (atomic%) are 0.001 ≦ α / (α + β + γ + δ) ≦ 0.05 0.01 ≦ β / (α + β + γ + δ) ≦ 0.10 0.65 ≦ γ / (α + β + γ + δ) ≦ 0.85 0.10 ≦ δ / (α + β + γ + δ) ≦ 0.27 β / α ≧ 1 and recrystallization of the optical recording layer Upper limit linear velocity is 7-12m
An optical recording medium characterized by being / s. 2) The alloy further has γ / (γ + δ) = 0.65-
The optical recording medium according to 1), which has a composition of 0.95. 3) The light reflection layer is composed of a silver single-layer film having a thickness D (Ag) and a purity of 99 wt% or more 1) or 2)
The optical recording medium described. 4) In an optical recording medium having a lower protective layer, an optical recording layer, an upper protective layer, and a light reflecting layer on a substrate, the light reflecting layer is made of silver having a film thickness D (Ag) and a purity of 99 wt% or more, and an upper portion. The relationship with the film thickness D (TL) of the protective layer is 5 × D (TL) ≦ D (Ag) ≦ 15 × D (TL), and the composition formula of the alloy which is the main component of the optical recording layer is represented by ( A
g and / or Ge) α (In and / or Ga and / or Bi) βSbγTeδ, where α, β, γ and δ (atomic%) are 0.001 ≦ α / (α + β + γ + δ) ≦ 0.05 0.01 ≦ β / (α + β + γ + δ) ≦ 0.10 0.65 ≦ γ / (α + β + γ + δ) ≦ 0.85 0.10 ≦ δ / (α + β + γ + δ) ≦ 0.27 β / α ≧ 1.5, and the optical recording layer Crystallization upper limit linear velocity is 14 to 21
An optical recording medium characterized by being m / s. 5) The alloy is further γ / (γ + δ) = 0.65-
4. The optical recording medium according to 4), which has a composition of 0.95. 6) The light reflection layer is composed of a silver single layer film having a thickness D (Ag) and a purity of 99 wt% or more 4) or 5)
The optical recording medium described. 7) The upper protective layer is composed of two or more layers, and has a film thickness TL1 of a layer in contact with the optical recording layer (first upper protective layer) and a film thickness TL2 of a layer in contact with the light reflecting layer (second upper protective layer). Ratio TL1 /
TL2 is 1.5 <= TL1 / TL2 <= 6.5, The optical recording medium in any one of 1) -6) characterized by the above-mentioned.

The present invention will be described in detail below. In the case of an optical recording medium that enables multi-speed recording and CAV recording, there is a difference in recording speed of up to 2.5 times between the minimum recording speed and the maximum recording speed. It has been found that the larger the thermal conductivity of the light reflecting layer of the optical recording medium, the better in order to enable high-speed recording and erasing in such a wide linear velocity. Specifically, sterling silver was judged to be optimal. Therefore, as a result of diligent studies on the problems of the Ag reflective layer, in order to obtain a light reflectance of 90% or more, which is a characteristic of Ag, as the light reflective layer of an optical recording medium, the Ag content of the light reflective layer is 99 w.
It has been found that it is effective if the content is t% or more, preferably 99.9 wt% or more. The crystal grain boundary of the Ag light reflecting layer is
The presence of grain boundaries affects the high thermal conductivity of Ag, because the thermophysical properties of Ag are very different. Such grain boundaries greatly change depending on the substrate temperature, the film forming speed, the film forming pressure, and the like. Further, when the Ag film is laminated twice or more, grain boundaries are generated at the interface between the first layer and the second layer, and the thermal conductivity is lowered. Therefore, when Ag is used as the light reflecting layer, Is preferred. Further, in order to increase the thermal conductivity, it is desirable to use a larger crystal grain size. Further, it has been found that the film thickness capable of obtaining high thermal conductivity and high light reflectance of Ag is largely deviated from the optimum film thickness design of the conventional optical recording medium, especially the phase change type optical recording medium.

In the conventionally known optical recording medium having a layer structure as shown in FIG. 1, when Ag alloy or Al alloy is used for the reflective layer, (1) recording sensitivity, (2) reflectance,
When (3) signal amplitude and (4) overwrite performance are balanced, the thickness of the light reflection layer is about 140 nm and the thickness of the upper protection layer is about 30 nm. It was less than 5 times. The Ag light reflecting layer of the present invention is
It can be formed by various vapor deposition methods such as a vacuum vapor deposition method, a sputtering method, a plasma CVD method, a photo CVD method, an ion plating method and an electron beam vapor deposition method. The film thickness is 50 to 200 nm, preferably 70 to 160
It is good to set it to nm. The film forming speed is 50 ~ 2000Å /
s, preferably 100 to 1500Å / s, but considering the variation in film thickness and productivity, 300 to 1500Å / s
s is particularly preferred.

FIG. 2 shows an example of the layer structure of the optical recording medium according to the present invention. The basic constitution is that the lower protective layer 2, the optical recording layer 3, and the first upper protective layer 4 are formed on the transparent substrate 1 having the guide groove.
a, the second upper protective layer 4b, the Ag light reflecting layer 5 ', and the overcoat layer 6 are further formed, and the cover substrate 9 is bonded thereto via the adhesive layer 8 or the printing layer 7 is formed.
It is also possible to provide. As the cover substrate 9,
Although only a transparent substrate may be used, a single-plate information disc having the above-mentioned overcoat layer 6 may be laminated. It is also possible to use the overcoat layer also as the adhesive layer to form one layer. The material of the substrate is usually glass, ceramics, or resin, and a resin substrate is suitable in terms of moldability and cost. Examples of resins include polycarbonate,
Acrylic resin, epoxy resin, polystyrene, acrylonitrile-styrene copolymer resin, polyethylene, polypropylene, silicone resin, fluorine resin, AB
Examples thereof include S resin and urethane resin, and polycarbonate and acrylic resin, which are excellent in moldability, optical characteristics and cost, are preferable.

However, the optical recording medium of the present invention is a DVD-RO.
In the case of application to a M-compatible rewritable optical recording medium, it is desirable to give the following specific conditions. That is, the width of the guide groove formed in the substrate used is 0.
10 to 0.40 μm, preferably 0.15 to 0.35 μm
And the depth of the guide groove is 15 to 45 nm, preferably 20.
It is about 40 nm. The thickness of the substrate is 0.
55 to 0.65 mm is suitable, and the thickness of the disc after lamination is preferably 1.1 to 1.3 mm. These substrate grooves improve the reproduction compatibility in the DVD-ROM drive. Further, the optical information recording medium of the present invention is C
When applied to the D-RW medium, the width of the guide groove is 0.2.
5 to 0.65 μm, preferably 0.30 to 0.60 μm,
The depth of the guide groove is 20 to 50 nm, preferably 25 to 45 n
m.

In order to enable high-speed multi-speed recording and high-speed CAV recording, it is necessary to secure an erasing power margin for erasing the amorphous mark, so that a material system that is more easily crystallized is selected. On the other hand, however, a material system that easily crystallizes tends to shorten the room temperature life of the recording mark. This is because the erasing by the light beam is similar to the mechanism that the recording mark disappears at room temperature. Therefore, high-speed multi-speed recording and high-speed CA
In order to realize the V recording, it is more preferable that the erasing by the light beam and the mechanism of disappearing the recording mark at room temperature are different. Specifically, the erasing by the light beam is performed by crystallization (melt erasing) after melting of the recording layer, that is, recrystallization, and the mechanism of disappearing the recording mark at room temperature does not pass through the melting process. It is desirable to use solid phase crystallization. When such a recording method based on melt erasing is selected, a recording layer material having a low solid phase crystallization rate and a high melt recrystallization rate is suitable.

Therefore, as a result of studying a recording material system satisfying the above-mentioned physical properties, when an alloy having the following composition is contained as a main component, particularly high speed multi-speed recording and high speed CA accompanied by melt erasing are performed.
It has been found to be suitable for V recording. The alloy having the following composition does not have to be the total amount of the recording material, and other elements may be added or impurities may be mixed as long as the effects of the present invention can be achieved. (Ag and / or Ge) α
(In and / or Ga and / or Bi) βSbγTeδ
, Α, β, γ, δ (atomic%) is 0.001 ≦ α / (α + β + γ + δ) ≦ 0.05 0.01 ≦ β / (α + β + γ + δ) ≦ 0.10 0.65 ≦ γ / (α + β + γ + δ) ≦ 0.85 0.10 ≦ δ / (α + β + γ + δ) ≦ 0.27 β / α ≧ 1 Ag and Ge are element groups that reduce the recrystallization rate, and In, Ga, and Bi are recrystallization rates. Is a group of elements that increase Sb and Te are a group of elements that change the optical constant associated with the phase change of the recording layer.

When the content of Ag and / or Ge is 0.001 or more, the recording mark life (archival) and the recording performance life (shelf) are improved, and when it is 0.05 or less, 8
It is suitable for high speed recording of m / s or more. In and / or G
When a and / or Bi is 0.01 or more, it is effective in increasing the recrystallization rate, and when it is 0.10 or less, the durability against reproduction light can be improved. SbTe, which is a phase change alloy material that is the base of the recording layer, is
When b is 0.65 or more and Te is 0.27 or less, 8 m /
High-speed recording of s or more can be realized. Also, Sb is 0.85
Hereinafter, when Te is 0.10 or more, high-speed recording of 8 m / s or more can be performed, and recording conforming to the CD format or the DVD format can be realized with a practical semiconductor laser power.

Further, Sb / (Te + Sb) = γ / (γ +
Larger δ) is more suitable for high-speed recording (amorphization), but if γ / (γ + δ) is too large, the melting point tends to be high and the recording power tends to be high. Therefore, in order to realize high-speed recording with high sensitivity. Is γ / (γ + δ) = 0.65-
A range of 0.95 is preferred. Further, if β / α is set to 1 or more, the recording layer becomes suitable for high-speed recording of 8 m / s or more,
When β / α is 1.5 or more, a recording layer suitable for high speed recording of 16 m / s or more is obtained. For this SbTe material, Al, F
By adding elements such as e, Si, O, and N, it is possible to control recording / erasing sensitivity, signal characteristics, reliability, and the like. The addition ratio of these elements is 0.00001-
It is 5 wt%, preferably 0.001 to 2 wt%. 0.
If it is less than 0,0001 wt%, the effect of addition will not be expressed,
If it exceeds 5 wt%, the initialization (crystallization) cannot be performed well.

More preferably, it is considered that a material having a cubic lattice crystal structure having an isotropic crystal structure in an unrecorded state after initialization, preferably a NaCl type crystal structure, is also highly isotropic. It is preferable because a phase change with little variation can occur between the amorphous phase and the amorphous phase, and recording (amorphization) and erasing (crystallization) can be performed at high speed and uniformly. The thickness of the phase change type optical recording layer is 10 to
The thickness is 50 nm, preferably 12 to 30 nm. Further, considering the initial characteristics such as jitter, overwrite characteristics, and mass production efficiency, the thickness is preferably 14 to 25 nm. 10 nm
When the thickness is thinner, the light absorption ability is remarkably lowered, and it cannot serve as a recording layer. 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 excellent in mass productivity and film quality.

In order to realize high-speed multi-speed recording and high-speed CAV recording, it is necessary to adjust the recrystallization upper limit linear velocity that influences the recording / erasing characteristics of the optical recording medium according to the recording linear velocity. The recrystallization upper limit linear velocity defined in the present invention means that the optical recording medium rotating at a predetermined linear velocity is irradiated with semiconductor laser light with a power that melts the recording layer, and the reflectance of the optical recording medium decreases. It is the linear velocity at which to start. From a different point of view, it is considered that the phase change recording layer of the optical recording medium has an upper limit linear velocity at which it can be recrystallized after being rapidly cooled by melting with a semiconductor laser beam. FIG. 3 schematically shows the relationship between the reflectance and the linear velocity of the optical recording medium that is rotated at a predetermined linear velocity and is irradiated with continuous light of a semiconductor laser with a power that melts the recording layer. . In this figure, the reflectance of the optical recording medium begins to decrease when the semiconductor laser continuous light is irradiated at a linear velocity of 14 m / s or more. At this time, the recrystallization upper limit linear velocity defined in the present invention is 14 m / s.

The upper limit linear velocity of recrystallization is (1) substrate temperature,
(2) Recording layer composition, (3) Recording layer film formation rate, (4) Thermophysical properties of each layer, (5) Residual gas species and partial pressure during film formation, (6)
It varies depending on the initialization conditions. The upper limit linear velocity of recrystallization also depends on the shape of the guide groove of the substrate. When the groove width is small and the groove is deep, the recrystallization upper limit linear velocity increases. When the substrate temperature decreases, the amount of water vapor taken into the recording film increases, disturbing the order of the recording layer structure and promoting amorphization. As a result, the upper limit linear velocity of recrystallization becomes small. In addition, when the substrate temperature is high, the amount of water vapor taken in decreases and crystal nuclei are formed in the early stage of recording layer formation,
Since the recrystallization of the recording layer is promoted, the recrystallization upper limit linear velocity becomes large. The recording layer composition determines the basic performance of the optical recording medium, as described above. However, with the recording layer composition alone, overwrite performance, matching with an optical recording device,
Total quality such as ease of manufacturing cannot be realized. When the film forming rate of the recording layer increases, the amount of gas taken into the recording film increases, disturbing the order of the recording layer structure and promoting amorphization. As a result, the upper limit linear velocity of recrystallization becomes small. If the thermophysical properties of each layer, especially the thermal conductivity of the light reflection layer and the upper protective layer, are large, rapid cooling is likely to occur, and the upper limit linear velocity of recrystallization is reduced. Since the initialization condition changes the crystal morphology of the recording layer, the recrystallization upper limit linear velocity depends on the crystal species and crystallinity.

As described above, the upper limit linear velocity of recrystallization depends on various manufacturing conditions, and a maximum difference of 6 m / s occurs. If the recrystallization upper limit linear velocity deviates by 6 m / s, the desired quality cannot be obtained. Therefore, it is important to adjust the above-mentioned manufacturing conditions of the optical recording medium so as to control the recrystallization upper limit linear velocity to a desired value while ensuring the productivity. The upper limit linear velocity of recrystallization is preferably a value slightly higher than the maximum recording linear velocity when the recording method by melting erasing is adopted. In particular, it is effective in reducing the jitter when recording twice, which is a problem as a high-speed phase change type optical recording medium. 2.4 times faster than DVD (8.5m /
s) In order to realize recording, the production conditions of the above (1) to (6) are set so that the recrystallization upper limit linear velocity is 7 to 12 m / s, preferably 8.5 to 11 m / s. Controlled.
As typical conditions, the substrate temperature is 20 to 60 ° C., the recording layer film forming speed is 30 to 150 Å / s, and the film forming pressure is 0.05 to 1 Pa.
Is mentioned. More preferably, the substrate temperature is 25 to 55.
C, recording layer film formation speed 40 to 130 Å / s, film formation pressure 0.
It is 02 to 0.1 Pa. Each of these various optical recording layers is preferably used as a single layer, but may be formed in multiple layers. At that time, it is possible to make the optical recording layer multi-layered by interposing a dielectric layer.

Materials for the lower protective layer and the first and second upper protective layers are SiO, SiO ₂ , ZnO, SnO ₂ and A.
Metal oxides such as l ₂ O ₃ , TiO ₂ , In ₂ O ₃ , MgO and ZrO ₂ ; Si ₃ N ₄ , SiN, AlN, Ti
N, BN, nitrides such as ZrN; ZnS, In2S _3,
Sulfides such as TaS ₄ ; SiC, TaC, B ₄ C, W
Carbides such as C, TiC, ZrC; diamond-like carbon, C, Si, or a mixture thereof. The second upper protective layer is made of C, Si, SiC, SiN, SiO,
A material containing at least one substance of SiO ₂ is desirable. These materials may be used alone as the protective layer, or may be mixed with each other. Moreover, you may contain an additive as needed. However, the melting points of the lower protective layer and the first and second upper protective layers need to be higher than that of the recording layer. The lower protective layer and the first and second upper protective layers may be formed by various vapor deposition methods such as vacuum deposition method, sputtering method, plasma CVD method, photo CVD method, ion plating method, and electron beam evaporation method. Can be formed. Among them, the sputtering method is excellent in mass productivity and film quality.

The film thickness of the lower protective layer greatly affects the reflectance, the degree of modulation and the recording sensitivity. In order to obtain good signal characteristics, it is preferable that the film thickness of the lower protective layer be 60 to 120 nm. The thickness of the first upper 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 cannot be achieved. Also, 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 is also deteriorated.
The film thickness of the second upper protective layer is 1 to 20 nm, preferably 2-1.
It is 0 nm, and more preferably 3 to 7 nm. The second upper protective layer needs to function as a chemically inactive layer between the Ag-based light reflecting layer and the first upper protective layer and / or as a heat dissipation adjusting layer. It facilitates mass transfer to and from the first upper protective layer and fails to function as a chemically inert layer. On the other hand, if the thickness is too large, the number of overwrites and the reflectance will decrease. In this way, the second upper protective layer has a predetermined thickness so as to balance the chemical inertness, the number of overwrites, and the reflectance. From the above, the film thickness of the first upper protective layer (T
L1) and the film thickness of the second upper protective layer (TL2) (TL1
/ TL2) is preferably 1.5 to 6.5.

An overcoat layer is formed on the Ag light reflection layer to prevent its oxidation. As the overcoat layer, a UV curable resin produced by spin coating is suitable. The thickness is preferably 3 to 15 μm, and 3 μm
If the thickness is made thinner, an increase in errors may be observed when the printing layer is provided on the overcoat layer,
If it is thicker than m, the internal stress becomes large, and the mechanical characteristics of the disk are greatly affected. As the hard coat layer, an ultraviolet curable resin produced by spin coating is generally used, and its thickness is preferably 2 to 6 μm.
If it is thinner than 2 μm, sufficient scratch resistance cannot be obtained, and if it is thicker than 6 μm, the internal stress becomes large and the mechanical properties of the disk are greatly affected. Its hardness is pencil hardness H that does not cause a large scratch even if it is rubbed with a cloth.
It is necessary to be above. It is also effective to mix an electrically conductive material as necessary to prevent electrostatic charge and prevent adhesion of dust and the like.

The printing layer is for the purpose of ensuring scratch resistance, label printing of brand names and the like, 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. . A suitable thickness is 3 to 50 μm. If the thickness is less than 3 μm, unevenness occurs during layer formation. 50μ
If it is thicker than m, the internal stress becomes large, and the mechanical characteristics of the disk are greatly affected.

As 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 spin-coated on the overcoat layer or the printing layer, depending on the material,
It is applied by a method such as roll coating or a screen printing method, and is subjected to treatments such as ultraviolet irradiation, heating, pressurization and the like, and is attached to the disk on the opposite surface. As the disc on the opposite side, as in the case of the cover substrate described above, only the transparent substrate may be used, but a single-plate information disc having the same overcoat layer 6 as described above may be attached. The material for the adhesive layer may or may not be applied to the bonding surface of the opposite disk. A pressure sensitive adhesive sheet can also be used as the adhesive layer. The thickness of the adhesive layer is not particularly limited, but is 5 to 100 μm, preferably 7 to 5 in consideration of the coating property of the material, the curability, the influence of the mechanical properties of the disk, and the like.
It is 0 μm. The range of the adhesive surface is not particularly limited, either, but D
When applied to a rewritable disc that is compatible with VD and / or CD, the position of the inner peripheral edge is Φ15 to 40 m in order to secure adhesive strength for the purpose of enabling high-speed recording.
m, preferably 15 to 30 mm.
Further, the glass transition temperature of the adhesive layer is preferably 100 ° C. or lower in order to secure the drop durability of the optical recording medium.

[0024]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 A polycarbonate substrate having a guide width of 0.25 μm and a groove depth of 27 nm and a thickness of 0.6 mm was injection-molded, and a lower protective layer, an optical recording layer, and a first upper part were formed on the substrate. Protective layer,
The second upper protective layer and the Ag light reflecting layer having a purity of 99.99 wt% were sequentially stacked by the sputtering method. ZnSSiO ₂ (SiO ₂ 20m) is used for the lower protective layer and the first upper protective layer.
ol%), and the film thickness was set to 80 nm and 11 nm, respectively. The optical recording layer contains Ag _0.5 Ge _1.5 In ₆ Sb.
₆₈ Te ₂₄ was used and the thickness was set to 16 nm. A SiC film having a thickness of 4 nm was used for the second upper protective layer. The Ag light reflection layer was a single layer having a thickness of 150 nm. As a result of the above, polycarbonate substrate / ZnSSiO ₂ (80 nm) / Ag
_{0. 5} Ge _1.5 In ₆ Sb ₆₈ Te ₂₄ (16 nm)
/ ZnSSiO ₂ (11 nm) / SiC film (4 nm) /
A layer structure of 99.99 wt% Ag (150 nm) was formed. Then, an overcoat layer was formed on the Ag light reflection layer by spin coating of an ultraviolet curable resin to prepare a single-disc disk of a phase change type optical recording medium. Next, the polycarbonate substrates were bonded together with an ultraviolet curable adhesive to obtain an optical recording medium having the layer structure illustrated in FIG. next,
With an initialization device having a large diameter LD (beam diameter 200 × 1 μm), a linear velocity of 3.0 m / s, an electric power of 850 mW,
With a feed of 110 μm, the entire surface was crystallized from the inner circumference toward the outer circumference at a constant linear velocity. In the above process, the substrate temperature was 50 ° C., the recording layer deposition rate was 100 nm / s, and the recrystallization upper limit linear velocity of the optical recording medium was 9.0 m / s.
The evacuation speed during film formation in each layer was controlled.

Then, the obtained phase change optical recording medium was recorded on a DVD-R at a recording linear velocity of 8.5 m / s, a wavelength of 650 nm, an NA (numerical aperture) of 0.65 and a recording power of 14.5 mW.
Optical recording was performed in the OM reproducible format. The minimum mark length is 0.4 μm. As a result, record once, twice,
1000 times Data to Clock Jite
r (data to clock jitter) is 6.9%,
It was good at 7.5% and 8.2%. Similarly, the recording linear velocity is 3.4 m / s, the wavelength is 650 nm, and the NA is 0.6.
5, the recording power was 14.0 mW, and the optical recording was carried out by the fusion erasing method in the DVD-ROM reproducible format. As a result, data to data was recorded once, twice, and 1000 times.
Clock Jitter is 6.0%, 6.5%, 7.
It was as good as 9%. In this way, by increasing the recrystallization upper limit linear velocity by 0.5 m / s faster than the target maximum recording linear velocity, high-speed multi-speed overwrite recording with a wide linear velocity of 3.4 to 8.5 m / s. Was realized. When this optical recording medium was reproduced with a DVD-ROM drive, it could be reproduced without any problem. 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, this optical recording medium is heated at a temperature of 80 ° C. and a humidity of 85% RH for 5 hours.
Even after the storage test that was left for 00 hours, the reflectance of 20
%, The degree of modulation was 63% and no change was observed.

Example 2 A 0.6 mm thick polycarbonate substrate having a guide groove with a groove width of 0.25 μm and a groove depth of 27 nm was injection-molded, and a lower protective layer, an optical recording layer and a first upper portion were formed on this substrate. Protective layer,
The second upper protective layer and the Ag light reflecting layer having a purity of 99.99 wt% were sequentially stacked by the sputtering method. ZnSSiO ₂ (SiO ₂ 20) is used for the lower protective layer and the first upper protective layer.
mol%) and the film thickness is 80 nm and 15 nm, respectively.
And The optical recording layer is Ag ₁ Ge ₂ In ₂ Ga ₆ Sb ₇₁
Te ₁₈ was used and the thickness was set to 16 nm. As the second upper protective layer, a SiN film having a thickness of 4 nm was used. The Ag light reflection layer is
It was a single layer with a thickness of 150 nm. As a result, the polycarbonate substrate / ZnSSiO ₂ (80 nm) / Ag ₁ Ge
₂ Ga ₆ In ₂ Sb ₇₁ Te ₁₈ (16 nm) / ZnS
SiO ₂ (15 nm) / SiN film (4 nm) /99.9
A layer structure of 9 wt% Ag (150 nm) was formed.
Then, an overcoat layer was formed on the Ag light reflection layer by spin coating of an ultraviolet curable resin to prepare a single-disc disk of a phase change type optical recording medium. Then, the polycarbonate substrates were bonded together with an ultraviolet curable adhesive to obtain an optical recording medium having the structure illustrated in FIG. Next, large diameter LD
With an initialization device having (beam diameter 200 × 1 μm), linear velocity 3.5 m / s, power 850 mW, feed 110
With a thickness of μm, the entire surface was crystallized from the inner circumference to the outer circumference at a constant linear velocity. In the above steps, the substrate temperature is 55 ° C., the recording layer film forming speed is 100 Å / s, and the Ag reflective film forming speed is 500 so that the upper limit linear velocity of recrystallization of the optical recording medium is 18 m / s.
Å / s, and the time from substrate molding to sputter film formation was controlled.

Next, a recording linear velocity of 17 m / s, a wavelength of 650 nm, an NA of 0.65, was added to the obtained phase change optical recording medium.
Optical recording was performed at a recording power of 14.5 mW in a DVD-ROM reproducible format. The minimum mark length is 0.4μ
m. As a result, D was recorded once, twice, and 1000 times.
ata to Clock Jitter is 6.7%,
The results were good at 7.2% and 7.9%. Similarly, optical recording was performed in a DVD-ROM reproducible format with a recording linear velocity of 7 m / s, a wavelength of 650 nm, an NA of 0.65, and a recording power of 14.0 mW. As a result, record once, twice,
1000 times Data to Clock Jite
The r was as good as 6.2%, 6.5% and 7.4%. In this way, by increasing the recrystallization upper limit linear velocity by 1 m / s faster than the target maximum recording linear velocity, high-speed multi-speed overwrite recording with a wide linear velocity of 7 to 17 m / s was realized. When this optical recording medium was reproduced with a DVD-ROM drive, it could be reproduced without any problem. 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, even after a storage test in which this optical recording medium was left for 500 hours in an environment of temperature 80 ° C. and humidity 85% RH, the reflectance was 20% and the degree of modulation was 63%, which was not observed.

[0029]

According to the first aspect of the present invention, it is possible to provide an optical recording medium conforming to the CD format and the DVD format and capable of high-speed multi-speed recording and high-speed CAV recording with a linear velocity of 8 m / s or more. According to the second aspect of the present invention, it is possible to provide an optical recording medium capable of high-speed recording with higher sensitivity. According to the third aspect of the present invention, it is possible to provide an optical recording medium that is more excellent in overwriting. According to the present invention 4, it is possible to provide an optical recording medium which complies with the CD format and the DVD format and enables high-speed multi-speed recording and high-speed CAV recording with a linear velocity of 16 m / s or more. According to the fifth aspect of the present invention, it is possible to provide an optical recording medium capable of high-speed recording with higher sensitivity.
According to the present invention 6, it is possible to provide an optical recording medium which is further excellent in overwriting. According to the present invention 7, it is possible to provide an optical recording medium which is excellent in storage reliability and conforms to the CD format and the DVD format and which is capable of high-speed multi-speed recording and high-speed CAV recording excellent in overwriting.

[Brief description of drawings]

FIG. 1 is a diagram showing a layer structure of a conventionally known optical recording medium.

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

FIG. 3 schematically shows the relationship between the reflectance and the linear velocity of an optical recording medium that is rotated at a predetermined linear velocity and is irradiated with continuous light of a semiconductor laser with a power that melts a recording layer. Fig.

[Explanation of symbols]

1 substrate 2 Lower protective layer 3 Optical recording layer 4 Upper protective layer 4a First upper protective layer 4b Second upper protective layer 5 Light reflection layer 5'Ag light reflecting layer 6 Overcoat layer 7 printing layers 8 Adhesive layer 9 Cover substrate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G11B 7/24 538 G11B 7/24 538E 538F B41M 5/26 B41M 5/26 XF term (reference) 2H111 EA04 EA23 EA33 EA40 FA01 FA12 FA14 FA23 FB05 FB09 FB10 FB12 FB17 FB21 FB30 5D029 JA01 JC20 LB03 LB07 LB11 MA13 MA14

Claims (7)

[Claims] 1. An optical recording medium having a lower protective layer, an optical recording layer, an upper protective layer and a light reflecting layer on a substrate, wherein the light reflecting layer is made of silver having a film thickness D (Ag) and a purity of 99 wt% or more. And the relationship with the film thickness D (TL) of the upper protective layer is 5 × D (TL) ≦ D (Ag) ≦ 15 × D (TL), and the composition formula of the alloy as the main component of the optical recording layer , (A
g and / or Ge) α (In and / or Ga and / or Bi) βSbγTeδ, α, β, γ, δ (atomic%) are 0.001 ≦ α / (α + β + γ + δ) ≦ 0.05 0.01 ≦ β / (α + β + γ + δ) ≦ 0.10 0.65 ≦ γ / (α + β + γ + δ) ≦ 0.85 0.10 ≦ δ / (α + β + γ + δ) ≦ 0.27 β / α ≧ 1 and recrystallization of the optical recording layer Upper limit linear velocity is 7-12m
An optical recording medium characterized by being / s. 2. The alloy further comprises γ / (γ + δ) =
The optical recording medium according to claim 1, having a composition of 0.65 to 0.95. 3. The light-reflecting layer has a film thickness D (Ag) of a purity of 99.
The optical recording medium according to claim 1 or 2, wherein the optical recording medium comprises a single layer film of silver of wt% or more. 4. In an optical recording medium having a lower protective layer, an optical recording layer, an upper protective layer and a light reflecting layer on a substrate, the light reflecting layer is made of silver having a film thickness D (Ag) and a purity of 99 wt% or more. And the relationship with the film thickness D (TL) of the upper protective layer is 5 × D (TL) ≦ D (Ag) ≦ 15 × D (TL), and the composition formula of the alloy as the main component of the optical recording layer , (A
g and / or Ge) α (In and / or Ga and / or Bi) βSbγTeδ, where α, β, γ and δ (atomic%) are 0.001 ≦ α / (α + β + γ + δ) ≦ 0.05 0.01 ≦ β / (α + β + γ + δ) ≦ 0.10 0.65 ≦ γ / (α + β + γ + δ) ≦ 0.85 0.10 ≦ δ / (α + β + γ + δ) ≦ 0.27 β / α ≧ 1.5, and the optical recording layer Crystallization upper limit linear velocity is 14 to 21
An optical recording medium characterized by being m / s. 5. The alloy further comprises γ / (γ + δ) =
The optical recording medium according to claim 4, having a composition of 0.65 to 0.95. 6. The light-reflecting layer has a purity of 99 with a film thickness D (Ag).
The optical recording medium according to claim 4 or 5, wherein the optical recording medium comprises a single layer film of silver of wt% or more. 7. A film of a layer TL1 of a layer (first upper protective layer) which is in contact with the optical recording layer and a layer (second upper protective layer) which is in contact with the light reflecting layer, wherein the upper protective layer is composed of two or more layers. The optical recording medium according to any one of claims 1 to 6, wherein the ratio TL1 / TL2 of the thickness TL2 is 1.5 ≤ TL1 / TL2 ≤ 6.5.