JP2002251779A - Phase change type optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase change type optical information recording medium to use short wavelength, for example, blue wavelength as recording wavelength, to enable high density recording and to make recording reproduction cope with ROM compatibility. SOLUTION: The phase change type optical information recording medium is characterized that the recording wavelength is 370 nm to 450 nm, an absorption ratio Ac of optical energy of a crystal in a recording layer 4 is smaller than an absorption ratio Aa of optical energy in amorphous. A piece of information is recorded with recording pitch of 0.3 μm to 0.52 μm in the phase change type optical information recording medium 1 which is constituted at least by providing the recording layer 4 on a substrate 2 in order to perform recording, deletion and reproduction of the information.

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 information recording medium having at least a recording layer provided on a substrate and recording, erasing and reproducing information, and more particularly to an optical information recording medium having an amorphous recording layer. The present invention relates to a phase-change optical information recording medium that performs information recording and erasing by reversibly changing a phase between a phase and a crystalline phase.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 8-124218 discloses a phase-change optical disk for recording, erasing, and reproducing information by using mark edge recording.
The recording layer, the second dielectric layer, the reflective layer, the third dielectric layer, and the ultraviolet curable resin layer are sequentially laminated, and the relationship between the crystal absorption rate Ac and the amorphous absorption rate Aa is Ac> Aa. And a transparent ultra-thin metal film or Si, G
An optical information recording medium characterized by using e and using a dielectric having a refractive index n of more than 1.5 as a third dielectric layer is disclosed. This prior art is based on the absorption rate Ac of the crystal.
Provides an optical information recording medium having an absorption rate Aa higher than that of an amorphous material. In a conventional phase-change recording medium that performs recording and reproduction using a reflectance difference, since the transmittance is the same between a crystal and an amorphous, there is a reciprocal relationship that the reflectance is high if the absorption is low. Therefore, in the above prior art, in other words, the reflectance of the crystal is to provide an optical information recording medium smaller than the reflectance of the amorphous,
Such an optical information recording medium loses compatibility with a ROM in terms of reflectance. Also, JP-A-11-3
No. 9716 discloses a medium having a large refractive index of 2.2 to 2.3. However, such a refractive index reflects too much a film thickness distribution to form an in-plane distribution. Will be uneven. Here, the in-plane distribution of the refractive index and the film thickness refers to, for example, those measured as follows. That is, when a disc of φ120 mm is applied, the inner diameter 22
10 points (for example, 22, 26, 30, 34, 38, 42,
46, 50, 54, and 58 mm) and 45 degrees in the disk circumferential direction (for example, 0, 45, 90, 13).
5, 180, 225, 270, 315 degrees), and the ellipsometer measures the refractive index and the film thickness at the ten points on the eight lines, that is, at a total of 80 points. Can be obtained.

[0003]

SUMMARY OF THE INVENTION The present invention provides a phase-change type optical information recording medium which has a short wavelength, for example, a blue wavelength, as a recording wavelength, enables high-density recording, and can achieve both recording and reproduction and ROM compatibility. The purpose is to:

[0004]

According to a first aspect of the present invention, there is provided a phase change type optical information recording medium having at least a recording layer provided on a substrate and recording, erasing and reproducing information. 370 nm to 450 nm, wherein the recording layer has a crystal light energy absorption ratio Ac smaller than the amorphous light energy absorption ratio Aa and is recorded at a recording pitch of 0.3 μm to 0.52 μm. This is a phase change type optical information recording medium. According to this configuration, high-density recording is possible and the reflectivity of the crystal is higher than the reflectivity of the amorphous, so that ROM compatibility can be obtained.

According to a second aspect of the present invention, there is provided a phase change type optical information recording apparatus according to the first aspect, wherein a recording pitch / a recording beam diameter (1 / e ² ) is 0.5 to 0.9. Medium. The value of recording pitch / recording beam diameter (1 / e ² ) is more preferably 0.6 to 0.85. If the recording pitch / recording beam diameter (1 / e ² ) is less than 0.5, the amount of erasing adjacent tracks (cross erase) increases, causing an increase in errors. , Erase adjacent track (cross erase)
Is reduced, but the recording capacity of the disk is reduced. According to this configuration, high-density recording is possible and the reflectivity of the crystal is higher than the reflectivity of the amorphous, so that ROM compatibility can be obtained.

According to a third aspect of the present invention, the recording linear density is 0.05
The phase change type optical information recording medium according to claim 1, wherein the optical recording medium has a thickness of 0.16 m / bit. The recording linear density is more preferably 0.11 to 0.16 μm / bit. This is because if it is less than 0.05 μm / bit, the recorded signal amplitude becomes small, which causes an increase in errors. Further, if the thickness exceeds 0.16 μm / bit, there is a disadvantage that the recording capacity does not increase. According to this configuration, high-density recording is possible and the reflectivity of the crystal is higher than the reflectivity of the amorphous, so that ROM compatibility can be obtained.

According to a fourth aspect of the present invention, a lower protective layer is provided on a substrate.
The recording layer, the upper protective layer, the heat radiation layer, and the ultraviolet curable resin are sequentially laminated, and the lower protective layer and the upper protective layer have a refractive index of 1.8 to 2.19.
3. The phase-change optical information recording medium according to item 1. According to this configuration, recording can be performed even at a short wavelength of about 400 nm, such as blue, and the degree of modulation can be obtained.

According to a fifth aspect of the present invention, there is provided a phase change type optical information recording medium according to the first aspect, wherein the material of the recording layer contains Ag, In, Sb and Te as main components.
According to this configuration, recording / reproduction and overwriting can be performed with high sensitivity.

According to a sixth aspect of the present invention, the substrate has a groove depth of 25 to
2. The phase-change optical information recording medium according to claim 1, wherein the optical information recording medium has a thickness of 50 nm. The groove depth of the substrate is more preferably 25 to 35 nm. This is because, when the groove is deeper than 50 nm, the reflectance decreases, the reflectance difference from the ROM increases, and it becomes difficult to detect the circuit.
If it is shallower than 25 nm, tracking becomes difficult.
According to this configuration, tracking becomes stable even at a short wavelength, and recording / reproduction becomes possible.

According to a seventh aspect of the present invention, the thickness of the recording layer is 7 to 2
The optical information recording medium according to claim 1, wherein the optical information recording medium has a thickness of 0 nm. The thickness of the recording layer is more preferably 7 to 15 nm. This is because, when the thickness of the recording layer is larger than 20 nm, when a smaller recording mark is recorded, the mark tends to be inclined in the depth direction, the reproduction jitter is deteriorated, and the error is increased. Because. If the film thickness is less than 7 nm, signal recording becomes difficult. According to this configuration, tracking becomes stable even at a short wavelength, and recording / reproduction becomes possible.

The invention according to claim 8 is the phase-change type optical information recording medium according to claim 1, wherein the recording and reproducing linear velocity is 1.2 to 14.0 m / s. According to this configuration, high linear velocity recording (overwrite) reproduction can be performed even with a short wavelength.

[0012]

FIG. 1 is a sectional view for explaining an example of a phase change type optical information recording medium of the present invention. The phase change type optical information recording medium 1 is formed on a transparent substrate 2 made of, for example, polycarbonate and a lower protective layer 3 (for example, ZnS.SiO 2).
₂ , using a dielectric material such as SiNx), recording layer 4
(For example, a phase change material such as AgInSbTe or GeSbTe is used), and the upper protective layer 5 (for example, ZnS.SiO
₂ , using a dielectric material such as SiNx), a heat radiation layer 6
(For example, a material having high thermal conductivity such as Al, an Al alloy, Au, or Ag is used), and an ultraviolet curable resin layer 7 is sequentially laminated. The present invention is not limited to such a layer configuration and material, but the use of the above-described layer configuration and material is preferable because recording / reproducing and overwriting characteristics are improved. It should be noted that such a phase-change optical recording medium 1 may be formed in a disk shape (phase-change type optical disk), a card shape, a sheet shape, or the like.

The phase change type optical information recording medium 1 of the present invention
A short wavelength of 70 nm to 450 nm, for example, a blue wavelength is set as a recording wavelength. Further, the recording pitch is set to 0.3 μm to 0.5
Since the thickness is 2 μm, the recording capacity can be increased only in the radial direction by DV.
D (recording pitch 0.74 μm: 4.7 GB) can be increased to 1.4 times to 2.4 times.

Next, the characteristics of the phase change recording medium of the present invention were examined. The test results are shown below. In the medium used in this test, the substrate 2 was a polycarbonate substrate having a thickness of 0.6 mm, and the lower protective layer 3 had a thickness of 40 mm.
μm, using ZnS · SiO ₂ as the material,
Is made of AgInSbTe with a thickness of 15 nm, and the upper protective layer 5 is made of ZnS with a thickness of 15 nm.
The heat radiation layer 6 is made of SiO ₂ , has a thickness of 120 μm, and uses Ag as a material. The ultraviolet curable resin layer 7 was 6 μm in thickness. The medium has a disk shape. The recording layer had an absorption ratio Ac of 0.7, an absorption ratio Aa of 0.85, and Ac <Aa was confirmed.

FIG. 2 is a diagram for explaining the relationship between the recording pitch of the phase-change optical information recording medium 1 of the present invention and the jitter. According to FIG.
If it is about nm, the jitter becomes 9% or less of Tw even if there is a cross talk at a recording pitch of 0.3 μm. 9% jitter
In the following, a medium and a drive can be created for error correction at the DVD level. In FIG. 2, NA means a numerical aperture (Numerical Aperture).

Further, according to the present invention, when recording at a blue wavelength, the recording pitch / recording beam diameter (1 / e ² ) is set to 0.1.
5 to 0.9 and a recording pitch of 0.3 μm to 0.5
By setting the thickness to 2 μm, high-density recording is possible, and the reflectance of the crystal becomes higher than that of the amorphous.
ROM compatibility is obtained, which is preferable. The relationship between the value of recording pitch / recording beam diameter (1 / e ² ) and the recording capacity was examined. Table 1 shows the results. Recording pitch / recording beam diameter (1 /
As e ² ) decreases, the recording capacity increases,
The recording density does not increase if the beam diameter remains the same. In this case, if the recording pitch is too small, the previously recorded mark will be erased. Therefore, in the present invention, the recording pitch / recording beam diameter (1 / e ² ) is set to 0.5
~ 0.9, and the recording pitch of the conventional 0.6μ
By setting the pitch to be smaller than m or 0.74 μm, the recording capacity could be improved.

[0017]

[Table 1]

In the present invention, the recording linear density is set to 0.05 to
0.16 μm / bit and recording pitch of 0.3 μm
By setting the thickness to m to 0.52 μm, high-density recording is possible and the reflectance of the crystal becomes higher than the reflectance of the amorphous, so that ROM compatibility is obtained, which is preferable. Table 2 shows the relationship between the linear density and the recording capacity. According to Table 2,
When the recording linear density is 0.05 to 0.16 μm / bit, a recording capacity of about 10 GB or more is possible.

[0019]

[Table 2]

When the refractive indexes of the lower protective layer 3 and the upper protective layer 5 are set to 1.8 to 2.19, as shown in Table 3 below, the transmittance is 80% or more, and light is sufficiently transmitted to the recording layer. The effect of enhancing the light is obtained, the reflectance at the blue wavelength becomes 20% or more, and the in-plane distribution of the reflectance of the medium ((ma
x.-min. ) / Ave. ) Is also less than 20%, which is preferable. However, when the refractive index is 2.2 or more, the in-plane distribution is 20%.
Above and big.

[0021]

[Table 3]

Further, according to the present invention, since the recording layer material contains Ag, In, Sb and Te as main components, recording and reproduction and overwriting can be performed with high sensitivity. Table 4 below shows that Ag, In, S
b and Te were used and GeS was used as the material of the recording layer.
The comparison result in the case of using bTe is shown. By using Ag, In, Sb and Te as the material of the recording layer, the jitter and the recording sensitivity are improved.

[0023]

[Table 4]

Further, according to the present invention, the groove depth of the substrate is set to 2
Preferably it is 5 to 50 nm. Table 5 below shows the relationship between the groove depth and the initial jitter, reflectance, modulation and tracking. 25 ~ 5 groove depth of substrate
By setting it to 0 nm, the jitter is as good as 9% or less, the reflectance is about 15%, the modulation is as large as 50% or more, and the tracking is also good. A more preferred groove depth is 20 to 45 nm.

[0025]

[Table 5]

According to the present invention, the thickness of the recording layer is 7 to
Preferably it is 20 nm. By setting the film thickness of the recording layer as described above, the initial jitter is 1 as shown in Table 6 below.
The window width Tw is about 8% or less, the reflectance is as high as 18% or more, and the jitter after overwriting is also good.

[0027]

[Table 6]

[0028]

According to the present invention, there is provided a phase-change type optical information recording medium which has a short wavelength, for example, a blue wavelength, as a recording wavelength, enables high-density recording, and can achieve both recording and reproduction and ROM compatibility.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a phase-change optical information recording medium according to the present invention.

FIG. 2 is a diagram for explaining a relationship between a recording pitch and a jitter (Jitter) of the phase change type optical information recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Phase-change optical information recording medium 2 Substrate 3 Lower protective layer 4 Recording layer 5 Upper protective layer 6 Heat radiation layer 7 UV curable resin layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/24 561 G11B 7/24 561P 563 563A

Claims (8)

[Claims] 1. A phase-change type optical information recording medium having at least a recording layer provided on a substrate and recording, erasing and reproducing information, has a recording wavelength of 370 nm to 45 nm.
0 nm, the light energy absorption rate Ac of the crystal of the recording layer is smaller than the amorphous light energy absorption rate Aa, and the recording pitch is 0.3 μm to 0.52 μm.
A phase change type optical information recording medium, characterized by being recorded by: 2. Recording pitch / recording beam diameter (1 / e ² )
2. The phase-change type optical information recording medium according to claim 1, wherein is 0.5 to 0.9. 3. A recording linear density of 0.05 to 0.16 μm /
2. The phase change type optical information recording medium according to claim 1, wherein the medium is a bit. 4. A lower protective layer, a recording layer, an upper protective layer, a heat radiation layer, and an ultraviolet curable resin are sequentially laminated on a substrate, and the lower protective layer and the upper protective layer have a refractive index of 1.8 to 2.
19. The phase-change optical information recording medium according to claim 1, wherein the number is 19. 5. A recording layer comprising Ag and I as main components.
2. The phase-change optical information recording medium according to claim 1, comprising n, Sb, and Te. 6. The optical information recording medium according to claim 1, wherein the groove depth of the substrate is 25 to 50 nm. 7. The phase-change optical information recording medium according to claim 1, wherein the recording layer has a thickness of 7 to 20 nm. 8. The recording and reproducing linear velocity is from 1.2 to 14.0.
2. The phase-change optical information recording medium according to claim 1, wherein the medium is m / s.