JP2002264522A - Phase change type information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase change type information recording medium of which the recording power is little and which is excellent in repetitive recording characteristics. SOLUTION: In the phase change type information recording medium enabling recording, erasure and reproduction of information, a layer of a material having a melting point of 970 deg.K or above and thermal conductivity of 50 mW/cmK or below and becoming amorphous is provided adjacently to a recording layer.

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 recording medium for recording, erasing and reproducing information by reversibly changing a recording layer between an amorphous phase and a crystalline phase.

[0002]

2. Description of the Related Art In the presentation of Fusion Research (ISOM / ODS99), a dielectric layer (SiN) and a reproducing layer (S
b), a dielectric layer (SiN), a recording layer (GeSbTe),
The structure is made of a dielectric layer (SiN) and Air, and the reproducing layer is made of Sb.
In this case, it is disclosed that Sb changes from a crystal to an amorphous state by a laser beam, and the near field generated at that time reaches the recording layer through a dielectric to allow high-density recording on the recording layer.

However, since the amount of return light is small, C /
N was as small as 20 dB or less, which was not realistic in terms of recording and reproduction. Sb is an unstable material, is easily crystallized, and has a problem in repetitive recording characteristics.

[0004] In addition, when high-density recording is performed, it can be practically used at present.
D (about 400 nm). When this LD is used, if the device for reducing the optimum recording power is devised in the media layer configuration, if a material having a low melting point and a low thermal conductivity is adjacent to or added to the recording layer, a recording There is a problem that recording cannot be performed normally due to melting.

In Japanese Patent Application Laid-Open No. 11-348428, Al-Cu is added to a SbTe-based phase change material, but the thermal conductivity is high and the recording sensitivity is poor, which is not suitable for high density recording.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a phase change type information recording medium having a low recording power and good repetitive recording characteristics.

[0007]

According to the first aspect of the present invention, in a phase change type information recording medium capable of recording, erasing and reproducing information, a melting point of 97% is provided adjacent to a recording layer.
An amorphous material layer having a temperature of 0 ° K or more and a thermal conductivity of 50 mW / cmK or less is provided.

According to the second aspect of the present invention, instead of the material layer, an amorphous material having a melting point of 970 ° K or more and a thermal conductivity of 50 mW / cmK or less is added to the recording layer.

In the invention of claim 3, the material is G
a2Te3. In the invention according to claim 4, the material is AgGeTe2. In the invention of claim 5, the material is CuGeS3. In the invention according to claim 6, the material is HgSe.

In the invention of claim 7, the material is C
uGaTe2. In the invention according to claim 8, the material is CuGaSe2. In a ninth aspect of the present invention, the recording layer contains SbTe.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. 1 is a transparent substrate made of polycarbonate, for example, ZnS. SiO2, SiNx, TaO
a lower protective layer 2 made of a dielectric material such as x, a recording layer 3 made of a phase change material such as AgInSbTe, GeSbTe, and the like. And the thermal conductivity is 50 mW / c
A material layer 4 that is amorphized below mK is provided. The material of the material layer 4 is Ga2Te3, AgGaTe2, C
uGeS3, HgSe, CuGaTe2, CuGaSe
Use 2 or the like.

Next, for example, ZnS. An upper protective layer 5 made of a dielectric material such as SiO2 or SiNx is formed, and a heat radiation layer 6 made of a material having a high thermal conductivity such as Al, an Al alloy Au, Ag, or an Ag alloy is formed thereon. U
A V effect resin layer 7 is formed and protected with a protective film 8.

By providing an amorphous material layer 4 having a melting point of 970 ° K or more and a thermal conductivity of 50 mW / cmK or less adjacent to the recording layer 3, the thermal conductivity is low, so that the recording sensitivity is lowered and the melting point is lowered. As it is high, it does not deteriorate during recording,
Further, since the crystallization and the amorphization are performed, the material can be designed as a part of the recording layer 3.

Further, even when the recording power is 12 mW, the recording layer 3
Is about 950 ° K without reaching 970 ° K after the temperature rise due to the recording power. Since the recording power of a blue LD is usually 10 mW or less, the effect of adjoining and adding a material having a melting point of 970 ° K or more is great.

In general, ZnSSiO 2 is used as a protective layer adjacent to a recording layer in a phase change medium,
Since its thermal conductivity is about 500 mW / cmK, about 1
Since it is 1/0, the recording sensitivity is improved.

The material for forming the material layer 4 to be amorphized may be added to the composition of the recording layer 3. However, when added, the recording jitter does not deteriorate if it is within 10 at% of the entire recording layer 3.

When the material of the material layer 4 is Ga 2 Te 3, the melting point is 1063 ° K and the thermal conductivity is 4.7 mW / cm.
Since the temperature is as low as K (300 ° K), the recording sensitivity is lowered and the recording layer 3 is not deteriorated during recording.

When the material of the material layer 4 is AgGaTe2, the melting point is 990 ° K and the thermal conductivity is 10 mW / c.
Since it is as low as mK (300 ° K), the recording sensitivity is lowered and the melting point is high, so that it does not deteriorate even when recording on the recording layer 3.

When the material of the material layer 4 is CuGeS3, the melting point is 1030 ° K and the thermal conductivity is 24 mW / c.
Since it is as low as mK (300 ° K), the recording sensitivity is lowered and the melting point is high, so that it does not deteriorate even when recording on the recording layer 3.

When the material of the material layer 4 is HgSe, the melting point is 1070 ° K and the thermal conductivity is 10 mW / cmK.
(300 ° K), the recording sensitivity is lowered, and the melting point is high, so that the recording layer 3 does not deteriorate even during recording.

When the material of the material layer 4 is CuGaTe2, the melting point is 2400 ° K and the thermal conductivity is 27 mW /
Since it is as low as cmK (300 ° K), the recording sensitivity is lowered and the melting point is high, so that it does not deteriorate even when recording on the recording layer 3.

When the material of the material layer 4 is CuGaSe 2, the melting point is 1970 ° K. and the thermal conductivity is 4240 m.
Since it is as low as W / cmK (300 ° K), the recording sensitivity is lowered and the melting point is high, so that it does not deteriorate even when recording on the recording layer 3.

Since the recording layer 3 contains at least SbTe, the recording layer (amorphous material) can be made small, so that high-density recording corresponding to a blue LD can be performed.

Next, the experimental results will be described. In the experiment, a phase change type information recording medium was prototyped with the configurations shown in the following Examples 1 to 6 and the conventional example, and the experiment was performed.

Example 1 Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag95Pd2Cu3 110 nm Upper protective layer 5 TaOx 20 nm Material layer 4 Ga2Te3 5 nm Recording layer 3 Ag6In6Sb66Te22 10 nm Lower protective layer 2 ZnS2 ZnSiO2 Polycarbonate 0.6mm

Example 2 Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag 100 nm Upper protective layer 5 SiNx 20 nm Recording layer 3 (Ag6In6Sb66Te22) 95 (AgGaTe2) 5 10 nm Lower protective layer 2 ZnSSiO2 40 nm Substrate 1 polycarbonate 0.6mm

Example 3 Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag 150 nm Upper protective layer 5 SiNx 20 nm Material layer 4 CuGeS3 5 nm Recording layer 3 Ag6In6Sb66Te22 15 nm Lower protective layer 2 ZnSSiO2 40 nm substrate 1 Polycarbonate 0.6mm

Example 4 Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag 100 nm Upper protective layer 5 TaOx 15 nm Recording layer 3 (Ag6In6Sb66Te22) 97 (HgSe) 3 12 nm Lower protective layer 2 ZnSSiO2 40 nm Substrate 1 polycarbonate 0.6mm

Example 5 Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag 100 nm Upper protective layer 5 ZnSSiO 2 10 nm Material layer 4 CuGaTe2 5 nm Recording layer 3 Ag6In6Sb66Te22 15 nm Lower protective layer 2 ZnSSiO2 38 nm substrate Polycarbonate 0.6mm

Example 6 Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag 100 nm Upper protective layer 5 SiNx 15 nm Recording layer 3 (Ag6In6Sb66Te22) 96 (CuGaSe2) 4 15 nm Lower protective layer 2 ZnSSiO2 40 nm Substrate 1 polycarbonate 0.6mm

[Conventional example] Protective film 8 Polycarbonate 0.6 mm UV effect resin layer 7 10 μm Heat dissipation layer 6 Ag 100 nm Upper protective layer 5 ZnSSiO2 15 nm Recording layer 3 Ag6In6Sb66Te22 15 nm Lower protective layer 2 ZnSSiO2 40 nm Substrate 1 Polycarbonate 0.6 mm

[Experimental Conditions] LD wavelength 405 nm NA = 0.65 EFM pattern (pattern during C / N measurement is a repetition of 3T) Recording strategy: See FIG. 2 Linear velocity 7 m / s Linear density 0.15 μm / bit (NA = 0.65) Track pitch 0.40 μm (NA = 0.65)

[Experimental Results] The jitters of Examples 1 to 6 and the conventional example were all on the order of 8% (clock / data jitter). This jitter is considered to be a sufficient characteristic for recording and reproduction conditions. Also, the C / N was all 40 dB or more. The recording power at which the jitter was minimized was as follows. Example 1: 7.4 mW Example 2: 7.0 mW Example 3: 7.6 mW Example 4: 7.2 mW Example 5: 7.0 mW Example 6: 7.4 mW Conventional Example: 9.0 mW Example The recording sensitivity of Examples 1 to 6 is 1 as compared with the conventional example.
Recording can be performed with a power of -2 mW lower.

[0034]

According to the first aspect of the present invention, the melting point is 970 ° K or more and the thermal conductivity is 50 mW / c adjacent to the recording layer.
By providing an amorphous material layer of mK or less,
Since the thermal conductivity is low, the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the second aspect of the present invention, the recording layer has a melting point of 970 ° K or more and a thermal conductivity of 50 mW / cmK.
By adding the following amorphous material to the phase change material as the recording layer, the thermal conductivity is low, the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the third aspect of the present invention, the layer adjacent to the recording layer or the material to be added is Ga 2 Te 3 and the melting point is 1
063 ° K and a thermal conductivity of 4.7 mW / cmK (3
00K), the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the invention of claim 4, the material adjacent to the recording layer or the material to be added is AgGaTe2, the melting point is 990 ° K, and the thermal conductivity is 10 mW / cmK (3
00K), the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the fifth aspect of the present invention, the material adjacent to the recording layer or the material to be added is CuGeS3, the melting point is 1030 ° K, and the thermal conductivity is 24 mW / cmK (3
00K), the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the sixth aspect of the present invention, the material adjacent to the recording layer or the material to be added is HgSe and the melting point is 10%.
70 ° K and a thermal conductivity of 10 mW / cmK (300
° K), the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the present invention, the material adjacent to the recording layer or the material to be added is CuGaTe2, the melting point is 2400 ° K, and the thermal conductivity is 27 mW / cmK.
(300 ° K), the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the eighth aspect of the present invention, the material adjacent to the recording layer or the material to be added is CuGaSe2, the melting point is 1970 ° K, and the thermal conductivity is 4240 mW / cm.
Since the temperature is as low as K (300 ° K), the recording sensitivity is lowered, and the melting point is high, so that it does not deteriorate during recording.

According to the ninth aspect of the present invention, the recording layer is made of SbT
Since the material system includes at least e and can reduce the size of a recording mark (amorphous), high-density recording corresponding to a blue LD is possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing experimental conditions.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower protective layer 3 Recording layer 4 Material layer 5 Upper protective layer 6 Heat dissipation layer 7 UV effect resin layer 8 Protective film

Claims (9)

[Claims] 1. A phase change type information recording medium capable of recording, erasing and reproducing information, comprising an amorphous material having a melting point of 970 ° K or more and a thermal conductivity of 50 mW / cmK or less adjacent to a recording layer. A phase change type information recording medium, comprising a material layer to be converted. 2. In place of the material layer, the recording layer has a melting point of 970 ° K. or more and a thermal conductivity of 50 mW / cmK.
2. A phase change type information recording medium according to claim 1, wherein the following material for amorphization is added. 3. The phase change type information recording medium according to claim 1, wherein said material is Ga2Te3. 4. The phase change type information recording medium according to claim 1, wherein said material is AgGeTe2. 5. The phase change type information recording medium according to claim 1, wherein the material is CuGeS3. 6. The phase change type information recording medium according to claim 1, wherein the material is HgSe. 7. The phase change type information recording medium according to claim 1, wherein said material is CuGaTe2. 8. The phase change type information recording medium according to claim 1, wherein said material is CuGaSe2. 9. The phase change type information recording medium according to claim 1, wherein the recording layer contains SbTe.