JPH06131700A - Optical recording medium - Google Patents

Abstract

(57) [Summary] [Object] To provide an optical recording medium in which corrosion, cracking, peeling and the like do not occur and in which the durability of the reflective layer is improved. [Structure] First group consisting of Au, Ag, Cu, Al, Mg, W, Pd, Ti, Zr, V, Nb, Ta, C
Second group consisting of r and Mo, B, Si, S, P and C
An optical recording medium comprising an amorphous reflective layer composed of at least one element contained in each of the third group consisting of At least one element contained in each of the second element group forming the coating film and the third element group which makes the alloy composed of the first element group and the second element group amorphous An optical recording medium comprising an amorphous reflective layer composed of an element. The optical recording medium of the present invention has excellent long-term reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium having an amorphous reflective layer.

[0002]

2. Description of the Related Art As a conventional optical recording medium, for example, FIG.
A structure as shown in is known. In FIG. 1, reference numeral 1 denotes a translucent donut plate-shaped substrate. A light absorbing layer 2 made of an organic dye or the like is formed on the substrate 1. The light absorption layer 2 absorbs the laser light emitted through the substrate 1 and is irradiated with heat to melt, vaporize, sublimate, deform or modify the light absorption layer 2 and form a pit on the surface of the substrate 1. It is a layer having an action. On the light absorption layer 2, a crystalline reflection layer 3 made of gold, silver, copper or the like is formed. The thickness of the reflective layer 3 is usually about 500 to 2000Å. Further, a protective layer 4 for protecting the reflective layer 3 and the like is formed on the reflective layer 3.

It is desired that the above optical recording medium can be reproduced by a player used for an existing compact disc. Therefore, it is practically required that the reflectance of the reflective layer is 65% or more.

[0004]

In the conventional optical recording medium using the crystalline reflective layer made of gold, silver, copper or the like, the reflective layer 3 is peeled off from the substrate 1 after long-term use. Or
Alternatively, the reflective layer 3 is corroded. Further, heat of several hundred degrees Celsius generated when recording with a laser easily causes cracks or peeling in the reflective layer 3 in the recording portion. For this reason, there is a problem that the error rate, which is an index of signal reading, increases, and the jitter remarkably deteriorates.

An object of the present invention is to provide an optical recording medium in which corrosion, cracking, peeling, etc. do not occur and the durability of the reflecting layer is improved.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is Au,
First group consisting of Ag, Cu, Al, Mg, W, P
d, Ti, Zr, V, Nb, Ta, Cr, Mo, a second group, and B, Si, S, P, C, a third group each containing at least one element An optical recording medium comprising a crystalline reflection layer.

Further, the gist of the present invention is composed of a first element group having a high reflectance, a second element group forming an oxide film, the first element group and the second element group. An optical recording medium comprising an amorphous reflective layer composed of at least one element contained in each element group of the third element group which makes the alloy amorphous.

Using each of the above groups or each of the metal groups,
A reflection layer having a thickness of 5 to 500 nm is formed on the substrate by a high frequency magnetron sputtering method, a DC magnetron sputtering method, an ion plating method, a cluster ion beam method or the like.

At this time, conditions are selected such that the formed reflective layer is amorphous. For example, the method for laminating the reflective layer is performed in a nitrogen atmosphere in which the flow rate of nitrogen gas is 1 to 500 sccm. Alternatively, while the substrate is sufficiently cooled and kept at a low temperature, a film is formed thereon with a high deposition rate. Furthermore, there are conditions such as selecting an alloy composition that tends to be amorphous.

Further, a fourth metal element containing at least one element selected from Fe, Ni and Co, Ge,
Y, As, Be, Sn, Bi, Sc, Hf, Sb, S
By adding the fifth metal element containing at least one element selected from e, Mn, Tc, etc., it is possible to obtain an amorphous reflective layer with improved corrosion, cracking, peeling and the like.

[0011]

The function of the present invention is not clear, but it is presumed as follows.

The first group consisting of Au, Ag, Cu and Al is a metal having a high reflectance and has a property of reflecting the light incident on the write-once recording medium. Mg, W, Pd,
2nd consisting of Ti, Zr, V, Nb, Ta, Cr, Mo
The group has the property of forming an oxide film. B, Si,
The third group consisting of S, P and C has a property that the alloys consisting of the first group and the second group are likely to be amorphous alloys.

The oxide film is chemically stable and prevents corrosion of the reflective layer. Furthermore, since the amorphous alloy does not include crystal grain boundaries, dislocations, and stacking faults, which are the characteristics of crystalline metals, they are excellent in corrosion resistance with respect to crystalline alloys. In addition, since the amorphous alloy has a small internal stress, the adhesiveness is improved and the peeling is difficult.

[0014]

EXAMPLES Examples will be described below, but the present invention is not limited thereto.

Since the optical recording medium according to the present invention has basically the same structure as the optical recording medium shown in FIG. 1, FIG. 1 will be used for the description of the embodiment.

(Example 1) Polycarbonate substrate 1
A cyanine-based organic dye was applied onto the above by a spin coating method to form a recording layer (light absorbing layer 2). Furthermore, 99.99
Using a composite target in which a Cr-Co-B-P-W sintered tip was placed on the% Ag target, the nitrogen flow rate was 1.
An amorphous reflective layer 3 having a film thickness of 150 nm was formed by a sputtering method in a nitrogen atmosphere of 00 sccm. An ultraviolet curable resin was spin-coated on the amorphous reflective layer 3 and was irradiated with ultraviolet rays to be cured to form a protective layer 4 having a thickness of about 8 μm.

The optical recording medium obtained by the above method is
When placed in an atmosphere of 85 ° C. and 85% RH for 200 hours, no abnormality in appearance such as peeling of the reflective layer 3 was observed.

A semiconductor laser having a wavelength of 780 nm was irradiated at a linear velocity of 1.2 m / sec and a recording power of 6.0 mW to record an EFM signal on the obtained optical recording medium. A commercially available CD player (Aurex) is used as the optical recording medium.
When the error rate and the jitter were measured by reproducing at XR-V73, the wavelength of the reproduction light was 780 nm), the values were 1 cps and 20 nsec, and a good reproduction signal could be obtained.

The amorphous reflective layer 3 on the slide glass substrate was dipped in a 10 wt% NaCl aqueous solution at 60 ° C. for 5 hours and the change in reflectance was measured with a semiconductor laser of 780 nm. It didn't change later.

(Example 2) Au-Ti-B was formed on the substrate 1 on which the recording layer (light absorbing layer 2) was formed in the same manner as in Example 1.
-Si-Ni sintering target is used and nitrogen flow rate is 2
Amorphous reflective layer 3 having a film thickness of 100 nm formed by a high frequency magnetron sputtering method in a nitrogen atmosphere of 00 sccm.
An optical recording medium having

The reflective layer 3 was formed in the same manner as in Example 1.
Abnormalities in appearance, error rate, jitter, and changes in reflectance were measured and no abnormality was found.

(Example 3) Ag-Mg-W was formed on the substrate 1 on which the recording layer (light absorbing layer 2) was formed in the same manner as in Example 1.
Using a B-Si sintered target, the nitrogen flow rate is 30.
In a nitrogen atmosphere of sccm, an amorphous reflective layer 3 having a film thickness of 200 nm was formed by an ion beam method.

Then, the reflective layer 3 was formed in the same manner as in Example 1.
Abnormalities in appearance, error rate, jitter, and changes in reflectance were measured and no abnormality was found.

(Example 4) Ag-Cu-C was formed on the substrate 1 on which the recording layer (light absorbing layer 2) was formed in the same manner as in Example 1.
Using the r-B-W sintered target, the nitrogen flow rate is 30.
An amorphous reflection layer 3 having a film thickness of 100 nm was formed by an ion beam method in a nitrogen atmosphere of 0 sccm.

The reflective layer 3 was formed in the same manner as in Example 1.
Abnormalities in appearance, error rate, jitter, and changes in reflectance were measured and no abnormality was found.

(Example 5) Ag-Mg-W was formed on the substrate 1 on which the recording layer (light absorbing layer 2) was formed in the same manner as in Example 1.
-Si-S alloy target was used and the nitrogen flow rate was 50.
In a nitrogen atmosphere of sccm, a 100 nm-thick amorphous reflective layer 3 was formed by a sputtering method.

The same procedure as in Example 1 was applied to this to form the reflection layer 3
Abnormalities in appearance, error rate, jitter, and changes in reflectance were measured and no abnormality was found.

Even when the elements of the second and third groups other than those shown in Examples 1 to 5 were used, the same results as in Examples 1 to 5 were obtained.

(Comparative Example 1) A cyanine organic dye was applied onto a polycarbonate disc substrate 1 by a spin coating method to form a recording layer (light absorbing layer 2). Furthermore, 9
The reflective layer 3 having a film thickness of 150 nm was formed by a sputtering method using a 9.99% Ag target. An ultraviolet curable resin was spin-coated on the amorphous reflective layer 3 and irradiated with ultraviolet rays to be cured to form a protective layer 4 having a thickness of about 8 μm.

The optical recording medium obtained by the above method is
When placed in an atmosphere at 85 ° C. and 85% RH for 200 hours, many pinholes were visually observed.

Further, a semiconductor laser having a wavelength of 780 nm was irradiated at a linear velocity of 1.2 m / sec and a recording power of 6.0 mW, and an EFM signal was recorded on the obtained optical recording medium. A commercially available CD player (Aurex) is used as the optical recording medium.
When the error rate and the jitter were measured by reproducing with XR-V73, the wavelength of the reproducing light was 780 nm), the values were 200 cps and 30 nsec, and a defective reproducing signal with a lot of noise was obtained.

On the other hand, at the time of the above-mentioned sputtering, a slide glass was put into the chamber to form a reflection layer, and the structure of the reflection layer was measured by an X-ray diffraction method to show a crystal structure.

As described above, the amorphous reflective layer of the optical recording medium of the present invention has a high reflectance of Au, Ag, Cu,
Element group consisting of Al, Mg, W, Pd, Ti, Zr, V, Nb, Ta, Cr, which can form an oxide film,
B, Si, S, P, C capable of making the element group composed of Mo and the alloy composed of the two element groups amorphous
Since it is composed of at least one element contained in each element group of the element group consisting of, the corrosion resistance, cracks, peeling, etc. do not occur and the durability is improved.

[0034]

As described above, the optical recording medium of the present invention has improved durability and excellent long-term reliability.

[Brief description of drawings]

FIG. 1 is a partially cutaway schematic perspective view showing an example of the structure of an optical recording medium.

[Explanation of symbols]

 1 substrate 2 light absorption layer 3 reflection layer 4 protective layer

Claims (2)

[Claims] 1. A first group of Au, Ag, Cu, Al, Mg, W, Pd, Ti, Zr, V, Nb, T.
a, Cr, Mo second group, B, Si, S,
An optical recording medium comprising an amorphous reflective layer composed of at least one element included in each of the third group consisting of P and C. 2. Amorphous alloy composed of a first element group having a high reflectance, a second element group forming an oxide film, and the first element group and the second element group. An optical recording medium comprising an amorphous reflective layer composed of at least one element included in each element group of the third element group.