JP3129497B2 - Phase change type optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable phase-change optical recording medium.

[0002]

2. Description of the Related Art Rewritable optical recording media include phase-change optical recording media and magneto-optical recording media. FIG. 2 shows a schematic cross-sectional view of a phase change optical recording medium. The optical recording layer 3 is melted and semi-melted by laser irradiation, becomes amorphous, and records information by a difference in reflectance. At this time, the optical recording layer 3 is protected by the protective layers 2 and 4 for the purpose of preventing the optical recording layer 3 from evaporating and deforming due to the melting or semi-melting state, protecting the optical recording layer 3 from the air atmosphere, or insulating the substrate. In general, pinching is carried out (JP-A-63-103453).
(Matsushita) A protective layer made of ZnS.SiO ₂ or other mixture. However, the prior art has the following problems.

As a protective layer, "S" such as ZnS.SiO _{2 is used.}
When a compound containing When the conventional layer configuration shown in FIG. 2 is adopted because the binding energy between “S” and Ag in the recording layer is large, the composition of the recording layer changes. The problem of deterioration of the repetition characteristics occurs.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art and to provide a phase change type optical recording medium having good recording, erasing and repetition characteristics.

[0005]

The structure of the present invention for solving the above problems is a phase change type optical recording medium as described in the claims.

More specifically, a first protective layer 2, an optical recording layer containing Ag, a second protective layer 4, and a heat radiation layer 5 are sequentially formed on a substrate 1, and a laser beam is applied to the optical recording layer 3. In a phase change type optical recording medium for recording, reproducing and erasing information utilizing a reversible phase transformation caused by light irradiation, the first and second protective layers are adjacent to the optical recording layer 3 containing Ag. SiN or nitride, such as AlN or SiC, ZnS on the opposite side of the recording layer containing Ag and the recording layer containing Ag
· A phase-change optical recording medium, characterized in that a compound layer containing S such as SiO _2.

FIG. 1 is a sectional view showing an example of the structure of a phase change type optical recording medium according to the present invention. A first protective layer 2, an optical recording layer 3, and a second protective layer 4 are formed on a transparent substrate 1. And heat radiation layer 5
And a first protective layer and a second protective layer, which are formed on the side opposite to the optical recording layer containing Ag and the protective layers 2-1 and 4-1 adjacent to the optical recording layer. 2,4-2.

The substrate 1 is preferably made of a material having excellent light transmittance, heat resistance, weather resistance and chemical resistance. Plastic and glass satisfy this requirement, and plastic guide grooves and pits can be formed easily and inexpensively by 2P method or injection molding, and glass can be formed by tracking etching grooves or dry etching by contact exposure method. Pits can be formed. When a plastic is used, a material such as polycarbonate or amorphous polyolefin is preferably used. The first protective layer 2 provided on the substrate 1 is a feature of the present invention, and is composed of the protective layer 2-1 and the protective layer 2-2, and the corrosion of the optical recording layer containing Ag due to external moisture or the like. The purpose is to provide a passivation effect to prevent the occurrence of heat, to prevent evaporation and deformation due to laser irradiation, and to insulate the substrate. Thousands of angstroms are formed on the protective layer 2-1.
It is possible to form a film without generating defects such as peeling and cracking up to the thickness of the film, and furthermore, ZnS / SiO ₂ or the like having a low coefficient of thermal expansion and excellent heat insulation is used. For example, SiN, SiC, AlN or the like containing only an element having a small binding energy with Ag contained in the optical recording layer is used. The first protective layer 2 is formed by a sputtering method or a vapor deposition method, and the protective layer 2-1 and the protective layer 2-2 each have a thickness of 100.
It is formed to a thickness of 0 to 3000 ° and 50 to 500 °.

For the optical recording layer 3, an alloy containing at least one chalcogen group element such as Se, Te, etc. and Ag is used. As such an alloy, for example, AgInTeS
b. The optical recording layer 3 is formed to a thickness of 200 to 2000 ° by a sputtering method or a vapor deposition method.

The second protective layer 4 is a feature of the present invention similarly to the first protective layer, and includes a protective layer 4-1 and a protective layer 4-2. For the protective layer 4-1, ZnS · SiO ₂ or the like is used. For the protective layer 4-2, SiN, SiC, Al
N or the like is used. A sputtering method and a vapor deposition method are used for forming the second protective layer, and the protective layer 4-1 and the protective layer 4-2 are formed to have a thickness of 1000 to 3000 Å and 50 to 500 そ れ ぞ れ, respectively.

The heat radiation layer 5 is generally made of Al or an Al alloy having a high thermal conductivity. The heat radiation layer 5 is formed to a thickness of 200 to 2500 degrees by a sputtering method, an evaporation method, or the like.

Although one configuration example according to the present invention has been described above, the present invention is not limited to this configuration example only. For example, an organic cover layer may be provided on the reflective layer 5 or an adhesive layer may be provided. Various modifications and changes are possible, for example, a two-sided recording type in which the medium is bonded through the media.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, using a ZnS · SiO ₂ targets on polycarbonate substrate 1, a protective layer 2-1 made of ZnS · SiO ₂ in an Ar atmosphere by sputtering, on the , A protective layer 2-2 made of SiN was formed by sputtering in an Ar and N atmosphere.

The optical recording layer 3 uses a target having an atomic ratio of Ag: In: Te: Sb of 1: 1: 2: 4.
The film was formed in an r atmosphere.

The protective layer 4-1 was formed in the same manner as the protective layer 2-1, and the protective layer 4-2 was formed in the same manner as the protective layer 2-2.

The heat radiation layer was formed in an Ar atmosphere using an Al-7 wt% Ti target. The thickness of each of the protective layers 2-1 is 2,000, and the thickness of the protective layer 2-2 is 100.
Å, the optical recording layer is 1000Å, and the protective layer 4-1 is 1000１０００
Å, the protective layer 4-2 is 100Å, and the reflective heat dissipation layer 5 is 500Å.
And

As a comparative example, a disk having the layer structure shown in FIG. 2 was manufactured. The protective layer 2 and the protective layer 4 are both made of ZnS.SiO ₂ , each having a thickness of 2000
1000 °. The optical recording 3 and the heat radiation layer 5 were the same as in the example.

Although one configuration example according to the present invention has been described above, the present invention is not limited to this configuration example only. For example, an organic cover layer may be provided on the reflective layer 5 or an adhesive layer may be provided. Various modifications and changes are possible, for example, a two-sided recording type in which the medium is bonded through the media.

Each disk is irradiated with a laser beam for 10 minutes.
After initializing with mw, recording and erasing are repeated with write power of 12 mw and bias of 6 mw, and the recording characteristic becomes 45d.
The number of repetitions at which B or more and the erasure ratio of 25 dB or more were maintained was measured.

As a result, the disc of the embodiment could be repeated 100,000 times or more, whereas the disc of the comparative example was 1
By repeating about 15,000 times, the recording characteristics and the erasing ratio were reduced to 45 dB and 25 dB, respectively.

The initial recording characteristics and the erasing ratio were 50 dB and 40 dB in the examples, respectively.
In the comparative examples, they were 49 dB and 38 dB, respectively.

[0022]

As described above, according to the present invention, A
In a phase change optical recording medium having an optical recording layer containing g,
The optical recording layer side including Ag is made of SiN, Si
Recording, erasing characteristics and repetition characteristics were improved by using nitrides or carbides such as C and AlN, and using ZnS or a compound containing ZnS on the outside.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration of an optical recording medium of the present invention.

FIG. 2 is a schematic cross-sectional view showing a configuration of a conventional optical recording medium.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Protective layer 2-1 Protective layer 2-2 Protective layer 3 Optical recording layer 4 Protective layer 4-1 Protective layer 4-2 Protective layer 5 Heat dissipation layer

Claims (1)

(57) [Claims] An optical recording layer comprising at least a silver-containing optical recording layer, a protective layer, and a heat radiation layer on a substrate, and recording, reproducing, and erasing information by irradiating the optical recording layer with light energy. In the variable-type optical recording medium, the protective layer is composed of two layers, the protective layer adjacent to the optical recording layer is nitride or carbide, and the outer protective layer is zinc sulfide or a composite compound containing zinc sulfide. Characterized by a phase change optical recording medium.