JP2002288879A - Phase change type information recording medium - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a phase change type information recording medium excellent in recording density and sensitivity. SOLUTION: From a laser beam incident side, a light transmitting layer, a lower protective layer, a phase change type recording layer, a first upper protective layer, a second upper protective layer, and a reflective heat dissipation layer are laminated in this order. Thermal conductivity less than 10mW / cmK. A light transmission layer, a lower protection layer, a recording layer, an upper protection layer, and a reflective heat dissipation layer are laminated in this order,
The thermal conductivity of the lower protective layer or the upper protective layer is 10 mW / cmK or less. A light transmitting layer, a first lower protective layer, a second lower protective layer, a recording layer, an upper protective layer, and a reflective heat dissipation layer are stacked in this order;
The thermal conductivity of the second lower protective layer is 10 mW / cmK or less. A light transmitting layer, a first lower protective layer, a second lower protective layer, a recording layer, a first upper protective layer, a second upper protective layer, and a reflective heat dissipation layer are laminated in this order, and a second lower protective layer and a first upper protective layer Has a thermal conductivity of 1
Less than 0mW / cmK.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium for recording or reproducing information by using light such as a laser, and more particularly to a phase change type information recording medium having a high recording density or excellent sensitivity.

[0002]

2. Description of the Related Art Optical discs such as CD-R and CD-RW record sound, text, and image signals along a circumferential direction on a plastic circular substrate such as polycarbonate or a recording layer provided thereon. Then, a reflective layer is formed by vapor deposition or sputtering of a metal such as aluminum, gold, or silver on the surface, and a laser beam is incident from the substrate surface side to record and reproduce signals. In recent years, as the amount of information handled by computers and the like has increased, the signal recording capacity of optical disks such as DVD-RAMs and DVD-RWs has increased, and the density of signal information has been increasing. The recording capacity of a CD is about 650 MB,
Is about 4.7GB, but higher recording density is required in the future.

[0003] It has been proposed to shorten the laser wavelength used to realize such a high recording density medium to the blue light region. However, conventional DVD-RAM,
It is difficult to produce a phase-change optical disk having a high recording density and a high recording sensitivity using only the technology used for DVD-RW.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a phase-change type information recording medium having high recording density and excellent sensitivity.

[0005]

The inventor of the present invention has conducted intensive studies in order to solve the problems of the prior art, and as a result, has found a phase-change type information recording medium which meets the above-mentioned object. That is, according to the present invention, the following phase change type information recording medium is provided. (1) In an optical information recording medium using a phase change material as a recording layer, at least a light transmitting layer, a lower protective layer, a recording layer, a first upper protective layer, a second upper protective layer, A phase change type information recording medium, wherein the reflective heat dissipation layer is laminated in this order, and the first upper protective layer has a thermal conductivity of 10 mW / cmK or less. (2) The first upper protective layer is made of Ag ₁₉ Sb ₂₉ Te ₅₂ , In ₂ Te ₃ , Ga ₂ Te ₃
And the phase change type information recording medium according to (1), comprising at least one selected from AgSbSe ₂ and AgSbSe ₂ . (3) The thickness of the first upper protective layer is 1 to 50 nm (1)
Or the phase change type information recording medium according to (2). (4) In an optical information recording medium having a phase change material as a recording layer, at least a light transmitting layer, a lower protective layer, a recording layer, an upper protective layer, and a reflective heat dissipation layer are laminated in this order from the side where laser light is incident; A phase change type information recording medium, wherein the thermal conductivity of the upper protective layer is 10 mW / cmK or less. (5) The phase change type information recording medium according to (4), wherein the upper protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ . (6) The phase change type information recording medium according to (4) or (5), wherein the thickness of the upper protective layer is 1 to 50 nm. (7) In an optical information recording medium having a phase-change material as a recording layer, at least a light transmitting layer, a first lower protective layer, a second lower protective layer, a recording layer, an upper protective layer, A phase change type information recording medium, wherein the reflective heat radiation layer is laminated in this order, and the thermal conductivity of the second lower protective layer is 10 mW / cmK or less. (8) The phase-change information recording medium according to (7), wherein the second lower protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ . (9) The thickness of the second lower protective layer is 1 to 50 nm (7)
Or the phase change type information recording medium according to (8). (10) In an optical information recording medium having a phase change material as a recording layer, at least a light transmitting layer, a lower protective layer, a recording layer, an upper protective layer, and a reflective heat dissipation layer are laminated in this order from the side where laser light is incident; A phase change type information recording medium, wherein the lower protective layer has a thermal conductivity of 10 mW / cmK or less. (11) The phase-change information recording medium according to (10), wherein the lower protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ . (12) The thickness of the lower protective layer is 1 to 50 nm (10)
Or the phase change type information recording medium according to (11). (13) In an optical information recording medium having a phase change material as a recording layer, at least a light transmitting layer, a first lower protective layer, a second lower protective layer, a recording layer, and a first layer from the side where laser light is incident.
Phase change type information characterized in that an upper protective layer, a second upper protective layer, and a reflective heat dissipation layer are laminated in this order, and the thermal conductivity of the second lower protective layer and the first upper protective layer is 10 mW / cmK or less. recoding media. (14) The second lower protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ , and the first upper protective layer is made of Ag
(13) The phase-change information recording medium according to (13), comprising at least one selected from ₁₉ Sb ₂₉ Te ₅₂ , In ₂ Te ₃ , Ga ₂ Te ₃ and AgSbSe ₂ . (15) The phase-change information recording medium according to (13) or (14), wherein the thickness of the second lower protective layer and the first upper protective layer is 1 to 50 nm.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a phase change type information recording medium according to the present invention will be described in detail. 1 to 5 are schematic sectional views of an optical information recording medium according to one embodiment of the present invention. FIG. 1a shows a lower protective layer 2, a recording layer 3,
This example shows a configuration in which a first upper protective layer 4a, a second upper protective layer 4, a reflective heat radiation layer 5, and an overcoat layer 6 are laminated in that order. FIG. 2A shows an example in which a lower protective layer 2, a recording layer 3, an upper protective layer 4a, a reflective heat radiation layer 5, and an overcoat layer 6 are laminated on a substrate 1 in that order. FIG. 3A shows an example in which a first lower protective layer 2, a second lower protective layer 2a, a recording layer 3, an upper protective layer 4, a reflective heat dissipation layer 5, and an overcoat layer 6 are laminated on a substrate 1 in that order. It is shown. FIG. 4A shows an example in which a lower protective layer 2a, a recording layer 3, an upper protective layer 4, a reflective heat dissipation layer 5, and an overcoat layer 6 are laminated on a substrate 1 in that order. FIG. 5A shows that a first lower protective layer 2, a second lower protective layer 2a, a recording layer 3, a first upper protective layer 4a, a second upper protective layer 4, a reflective heat dissipation layer 5, and an overcoat layer 6 are formed on a substrate 1. This shows an example composed of configurations stored in that order. In any of the examples, the hard coat layer 8 can be provided on the mirror surface of the substrate.

FIGS. 1b, 2b, 3b, 4b,
FIG. 5B shows an example of an optical disc in the case of using a high NA objective lens for high recording density and irradiating laser light from a thin light transmitting layer on the side opposite to the substrate. Fig. 1b
Are the reflective heat radiation layer 5, the second upper protective layer 4, the first
Upper protective layer 4a, recording layer 3, lower protective layer 2, light transmitting layer 7
Are stored in that order.
FIG. 2B shows a reflective heat radiation layer 5 and an upper protective layer 4a on a substrate 1.
, A recording layer 3, a lower protective layer 2, and a light transmitting layer 7 are accumulated in that order. FIG. 3b shows a reflective heat dissipation layer 5, an upper protective layer 4, a recording layer 3, a second
This shows an example in which the lower protective layer 2a, the first lower protective layer 2, and the light transmitting layer 7 are accumulated in that order. Fig. 4b
Shows an example in which a reflective heat radiation layer 5, an upper protective layer 4, a recording layer 3, and a lower protective layer 2a and a light transmitting layer 7 are accumulated on a substrate 1 in that order. FIG. 5B shows a reflective heat radiation layer 5, a second upper protective layer 4, a first upper protective layer 4a,
This shows an example in which a recording layer 3, a second lower protective layer 2a, a first lower protective layer 2, and a light transmitting layer 7 are accumulated in that order. In any of the examples, the hard coat layer 8 can be provided on the light transmitting layer.

The material of the substrate 1 is usually glass, ceramics or resin, and a resin substrate is suitable in terms of moldability and cost. Examples of resins include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin,
Acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, etc., but polycarbonate resin, acrylic resin excellent in moldability, optical properties and cost Is preferred.

An uneven pattern is formed on one side of the substrate surface, and a protective layer, a recording layer, and the like are formed on this side. The thickness of the substrate is not particularly limited. Figures 1b, 2b,
In the case of FIG. 3b, FIG. 4b, and FIG. 5b, since laser light is not irradiated from the substrate side, there is no need to consider optical characteristics, and polyethylene terephthalate having excellent rigidity is preferable. There is no problem even if the substrate is colored.

As a material of the recording layer 3, a chalcogen-based alloy thin film is often used. For example, Ge-Te-based, Ge-Te-
Examples include Sb-based, Ge-Sn-Te-based, and Ag-In-Sb-Te quaternary alloy thin films.Sb-Te added with at least one element of Ag, In, Ge, etc. A crystalline thin film is suitable as a material for a recording layer because it has extremely good recording (amorphization) sensitivity / speed and erasing ratio. Other elements and impurities can be added to these recording layer materials for the purpose of further improving performance and reliability.

The recording layer using an inorganic material can be formed by various vapor deposition methods, for example, a vacuum deposition method, a sputtering method,
It can be formed by a CVD method, a photo CVD method, an ion plating method, an electron beam evaporation method, or the like. Among them, the sputtering method is excellent in mass productivity, film quality, and the like.

As the reflection heat radiation layer 5, Al, Au, Ag, Cu,
A metal material such as Ta or an alloy thereof can be used. In addition, Cr, Ti, Si, C
u, Ag, Pd, Ta, etc. are used. Such a reflective heat dissipation layer can be formed by various vapor phase epitaxy methods, for example, a vacuum evaporation method, a sputtering method, a plasma CVD method, a photo CVD method, an ion plating method, an electron beam evaporation method, or the like.
Among them, the sputtering method is excellent in mass productivity, film quality, and the like.

The protective layers 2 and 4 prevent the recording layer 3 from deteriorating.
To increase the adhesive strength of the recording layer 3 and the recording characteristics.
Such as SiO, SiO_Two, Zn
O, SnO_Two, Al_TwoO_Three, TiO_Two, In_TwoO_Three, M
gO, ZrO_TwoMetal oxides such as Si_ThreeN_Four, Al
Nitride such as N, TiN, BN, ZrN, ZnS, In
_TwoS _Three, TaS_FourSuch as sulfide, SiC, TaC, B_Four
Carbides such as C, WC, TiC, ZrC and diamonds
Carbon or a mixture thereof. This
These materials can be used alone as a protective layer.
Any mixture may be used. Also, if necessary, remove impurities.
May be included. The melting point of the protective layer may be higher than the recording layer
is necessary.

Such a protective layer is formed by various vapor phase growth methods, for example, a vacuum deposition method, a sputtering method, a plasma CVD method.
, An optical CVD method, an ion plating method, an electron beam evaporation method, or the like. Among them, the sputtering method is excellent in mass productivity, film quality, and the like.

It is a feature of the present invention that a material having low thermal conductivity is used for the protective layers 2a and 4a. Shows a thermal simulation of the recording layer portion in a case of radiating laser beam AlN respectively lower protective layer, a media using a ZnSSiO _2, Ga ₂ Te ₃ (heat distribution Rendering) 6-8. AlN, ZnSS
The thermal conductivities of iO ₂ and Ga ₂ Te ₃ are 823, 24,
It is 4.7 mW / cmK. It was found that the lower the thermal conductivity of the lower protective layer, the smaller the heat distribution reaching the recording layer. In addition, it was found that by providing a material having a low thermal conductivity for the upper protective layer, the recording layer was sufficiently heated even with a low power.

As a result of the thermal simulation, it was found that if the thermal conductivity was 10 mW / cmK or less, high recording density and high sensitivity could be achieved. Specifically, as the upper protective layer
Ag ₁₉ Sb ₂₉ Te ₅₂ , In ₂ Te ₃ , Ga ₂ Te ₃ , at least one selected from AgSbSe ₂ , and the lower protective layer is Ag ₁₉ Sb ₂₉ Te
₅₂ , In ₂ Te ₃ , Ga ₂ Te ₃ , and AgSbSe ₂ are used. Each thermal conductivity is 0.3,
6.9, 4.7, and 10.0 mW / cmK.

By providing the first upper protective layer 4a having a small thermal conductivity, the recording sensitivity is improved, and by performing recording with a low power, the cross erase is reduced.

Further, the second lower protective layer 2 having a low thermal conductivity
By providing a, the heat distribution reaching the recording layer is reduced, small pits can be formed, and the recording density can be increased. Ag ₁₉ Sb ₂₉ Te ₅₂ and AgSbSe ₂ are
Low melting point and high absorption, lower protective layer or
It is difficult to use as a single upper protective layer.

The thickness of the protective layers 2a and 4a is preferably 1 to 50 nm, and more preferably 3 to 15 nm. If it exceeds 50 nm, the repetitive recording performance is reduced. When the thickness is 1 nm or less, the function as the present invention cannot be achieved.

When a high NA objective lens is used, the light transmitting layer 7 is required to have a thickness of 0.3 mm or less. Examples of the material include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, etc. A polycarbonate resin and an acrylic resin which are excellent in characteristics and cost are preferable.

As a method of forming the light transmitting layer using the transparent sheet, there is a method of attaching a transparent sheet via an ultraviolet curable resin or a transparent double-sided pressure-sensitive adhesive sheet. Alternatively, an ultraviolet curable resin may be applied on the protective layer 2 and cured to form a light transmitting layer.

Further, an irregular pattern may be formed on the transparent sheet. In this case, no concavo-convex pattern is formed on the substrate 1. Instead, a protective layer, a recording layer, and a reflective heat dissipation layer are formed in reverse order on the side of the concavo-convex pattern of the transparent sheet, and the substrate is finally bonded.

As the hard coat layer 8, an ultraviolet curable resin produced by spin coating is generally used. An appropriate thickness is 1 to 8 μm. If it is 1 μm or less, sufficient scratch resistance cannot be obtained. If the thickness is 8 μm or more, the internal stress increases, which greatly affects the mechanical properties of the disk. The hardness must be equal to or higher than H, which is a pencil hardness that does not cause significant damage even when rubbed with a cloth. It is also effective to mix a conductive material as needed to prevent static charge and to prevent adhesion of dust and the like. The UV curable resin of the hard coat layer used has a viscosity of 4 in order to control the application position with good reproducibility and accuracy.
A value of 0 cps or more is desirable.

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

(Example 1) Diameter 12 cm, thickness 0.6 m
The surface has tracking guide irregularities due to continuous grooves
ZnSSiO on polycarbonate substrate_TwoConsisting of lower protection
Layer 40nm, Ag₁In ₇Sb₇₀Te_{twenty two}Recording layer of 12 nm, Ga
_TwoTe_Three5 nm first upper protective layer made of ZnSSiO _TwoConsisting of
2 Upper protective layer 7nm, reflective heat dissipation layer made of Ag 100nm
Into a film by a sputtering device and use a spin coater
To provide a phase change type information recording medium with an overcoat layer.
Done. Next, the early stage with a large-diameter semiconductor laser
The recording layer of the disc
Was.

(Embodiments 2 to 4)
A phase change type information recording medium was formed in the same manner as in Example 1 except that the upper protective layer was made of Ag ₁₉ Sb ₂₉ Te ₅₂ in Example ₂ , In ₂ Te ₃ in Example 3, and AgSbSe ₂ in Example 4. I got

(Example 5) Diameter 12 cm, thickness 0.6 m
The surface has tracking guide irregularities due to continuous grooves
ZnSSiO on polycarbonate substrate_TwoConsisting of lower protection
Layer 40nm, Ag₁In ₇Sb₇₀Te_{twenty two}Recording layer of 12 nm, Ga
_TwoTe_ThreeUpper protective layer made of 12 nm, reflective heat dissipation layer made of Ag
Films are formed by sputtering equipment in the order of 100 nm,
Phase change information by providing an overcoat layer
A recording medium was created. Next, a large-diameter semiconductor laser
Initialization of the recording layer of the disc by the initialization device having
Was performed.

Example 6 A phase change type information recording medium was obtained in the same manner as in Example 5, except that In ₂ Te ₃ was used for the upper protective layer.

(Embodiment 7) Diameter 12 cm, thickness 0.6 m
The surface has tracking guide irregularities due to continuous grooves
ZnSSiO on polycarbonate substrate_TwoThe first lower part consisting of
Protective layer 30 nm, Ga _TwoTe_Three5 nm second lower protective layer made of Ag
₁In₇Sb₇₀Te_{twenty two}12 nm recording layer made of ZnSSiO_TwoConsists of
Upper protective layer 12nm, reflective heat dissipation layer made of Ag 100nm
Into a film by a sputtering device and use a spin coater
To provide a phase change type information recording medium with an overcoat layer.
Done. Next, the early stage with a large-diameter semiconductor laser
The recording layer of the disc
Was.

Example 8 A phase change type information recording medium was obtained in the same manner as in Example 7, except that In ₂ Te ₃ was used for the second lower protective layer.

(Embodiment 9) Diameter 12 cm, thickness 0.6 m
The surface has tracking guide irregularities due to continuous grooves
Ga on a polycarbonate substrate_TwoTe_ThreeLower protective layer consisting of
30 nm, Ag₁In₇Sb ₇₀Te_{twenty two}12nm recording layer, ZnSSi
O_TwoUpper protective layer made of 12 nm, reflective heat dissipation layer 1 made of Ag
A film was formed by a sputtering apparatus in the order of
Phase change type information recording
A recording medium was created. Next, a large-diameter semiconductor laser
Of the recording layer of the disk by the initialization device
Processing was performed.

Example 10 A phase change type information recording medium was obtained in the same manner as in Example 9 except that In ₂ Te ₃ was used for the lower protective layer.

(Example 11) Diameter 12 cm, thickness 0.6
mm to make the tracking guide uneven by continuous grooves on the surface
ZnSSiO on polycarbonate substrate_TwoThe first lower part consisting of
Part protection layer 30 nm, Ga _TwoTe_ThreeA second lower protective layer of 5 nm,
Ag₁In₇Sb₇₀Te_{twenty two}Recording layer of 12 nm, Ga_TwoTe_ThreeConsists of
First upper protective layer 5 nm, ZnSSiO_TwoSecond protective layer made of
Sputtering equipment in order of 7nm, reflective heat dissipation layer made of Ag 100nm
The film is formed using a spin coater.
A phase change type information recording medium was prepared by providing a coating layer. About
With an initialization device having a large-diameter semiconductor laser.
Then, the recording layer of the disk was initialized.

(Examples 12 to 18) In Example 11, in Example 12, Ag ₁₉ Sb ₂₉ Te ₅₂ was used for the first upper protective layer.
In Example 13, Ga ₂ Te ₃ was used for the second lower protective layer. In Example 13, Ag ₁₉ Sb ₂₉ Te ₅₂ was used for the first upper protective layer. In ₂ Te ₃ was used for the second lower protective layer. In Example 14, the first upper protective layer was used. In ₂ Te ₃ for the protective layer, Ga ₂ Te ₃ for the second lower protective layer, and in Example 15, In ₂ T ₃ for the first upper protective layer.
e ₃ , In ₂ Te ₃ for the second lower protective layer.
Ga ₂ Te ₃ in the upper protective layer, an an In ₂ Te ₃ in the second lower protective layer, AgSbSe ₂ on the first upper protective layer in Example 17, the Ga ₂ Te ₃ to the second lower protective layer, in Example 18 AgSbSe for the first upper protective layer
₂ and Example 11 except that In ₂ Te ₃ was used for the second lower protective layer.
In the same manner as in the above, a phase change type information recording medium was obtained.

[0035] (Experimental Example 1 (Comparative Example)) diameter 12cm, lower protective layer 40nm made of ZnSSiO ₂ on a polycarbonate substrate having the unevenness of the tracking guide by a continuous groove in the surface at a thickness of 0.6mm, Ag ₁ In ₇ Sb Recording layer 1 consisting of ₇₀ Te ₂₂
2 nm, 60 nm of first upper protective layer made of Ga ₂ Te _3, 12 nm of second upper protective layer made of ZnSSiO ₂ , reflective heat dissipation layer 1 made of Ag
A film was formed by a sputtering apparatus in the order of 00 nm, and an overcoat layer was provided using a spin coater to prepare a phase change type information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

Comparative Example 1 A phase change type information recording medium was obtained in the same manner as in Experimental Example 1, except that the first upper protective layer was not provided.

Comparative Example 2 A phase change type information recording medium was obtained in the same manner as in Comparative Example 1, except that the upper protective layer was replaced with AlN. Each created medium was recorded under the following conditions. Laser wavelength 407nm NA = 0.65 linear velocity
6.5 m / s Track pitch 0.40 μm Recording at linear density 0.13 μm / bit, linear density 0.20 μm
The jitter at the time of recording at / bit and recording 100 times at a linear density of 0.20 μm / bit was measured. Table 1 shows the results. As is clear from Table 1, the recording sensitivity of the order of 7 mW was obtained in the example having the protective layer having a small thermal conductivity between the recording layer and the reflective heat radiation layer, and the thermal conductivity was between the recording layer and the light transmitting layer. In the embodiment having a protective layer having a small
Even at a high recording density of 13 μm / bit, a jitter of the order of 7% could be obtained.

[0038]

[Table 1]

Example 19 12 cm in diameter and 1.1 in thickness
Reflective heat dissipation layer 6 made of Ag on a polycarbonate substrate having irregularities of tracking guide by continuous grooves on the surface in mm
0 nm, a second upper protective layer 5 nm of ZnSSiO ₂ , a first upper protective layer 5 nm of Ga ₂ Te _3, a recording layer 10 nm of Ag ₁ In ₇ Sb ₇₀ Te ₂₂ , and a lower protective layer 30 nm of ZnSSiO _2. A film was formed by a sputtering apparatus, and a polycarbonate film having a thickness of 80 μm was attached via a double-sided pressure-sensitive adhesive sheet having a thickness of 20 μm to prepare a phase change type information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

(Examples 20 to 22) In Example 19, the first upper protective layer was changed to Ag ₁₉ Sb ₂₉ Te ₅₂ in Example 20.
A phase change type information recording medium was obtained in the same manner as in Example 19 except that In ₂ Te ₃ was used in Example 21 and AgSbSe ₂ was used in Example 22.

(Example 23) Diameter 12 cm, thickness 1.1
Reflective heat dissipation layer 6 made of Ag on a polycarbonate substrate having irregularities of tracking guide by continuous grooves on the surface in mm
0 nm, upper protective layer of Ga ₂ Te ₃ 7 nm, Ag ₁ In ₇ Sb ₇₀ Te ₂₂
Recording layer of 10 nm, lower protective layer 3 of ZnSSiO ₂
A film is formed by a sputtering apparatus in the order of 0 nm, and the thickness is 2
A polycarbonate film having a thickness of 80 μm was attached via a double-sided pressure-sensitive adhesive sheet having a thickness of 0 μm to prepare a phase change type information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

Example 24 A phase change type information recording medium was obtained in the same manner as in Example 23 except that In ₂ Te ₃ was used for the upper protective layer.

(Example 25) Diameter 12 cm, thickness 1.1
Reflective heat dissipation layer 6 made of Ag on a polycarbonate substrate having irregularities of tracking guide by continuous grooves on the surface in mm
0 nm, upper protective layer made of ZnSSiO ₂ 9 nm, Ag ₁ In ₇ Sb ₇₀ Te
_A recording layer made of ₂₂ nm, a second lower protective layer made of Ga ₂ Te _{3 having a} thickness of 5 nm, a first lower protective layer made of ZnSSiO _{2 having a} thickness of 30 nm were formed in this order by a sputtering apparatus, and further via a double-sided adhesive sheet having a thickness of 20 μm. An 80 μm-thick polycarbonate film was stuck to form a phase-change information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

(Example 26) In Example 25, the second
A phase change type information recording medium was obtained in the same manner as in Example 25 except that In ₂ Te ₃ was used for the lower protective layer.

(Example 27) Diameter 12 cm, thickness 1.1
Reflective heat dissipation layer 6 made of Ag on a polycarbonate substrate having irregularities of tracking guide by continuous grooves on the surface in mm
0 nm, upper protective layer made of ZnSSiO ₂ 9 nm, Ag ₁ In ₇ Sb ₇₀ Te
₂₂ nm recording layer, lower protective layer 2 made of Ga ₂ Te ₃
A film was formed by a sputtering apparatus in the order of 0 nm, and a polycarbonate film having a thickness of 80 μm was pasted through a double-sided pressure-sensitive adhesive sheet having a thickness of 20 μm to prepare a phase change type information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

(Example 28) A phase change type information recording medium was obtained in the same manner as in Example 27 except that In ₂ Te ₃ was used for the lower protective layer.

(Example 29) Diameter 12 cm, thickness 1.1
Reflective heat dissipation layer 6 made of Ag on a polycarbonate substrate having irregularities of tracking guide by continuous grooves on the surface in mm
0 nm, the second upper protective layer 5nm consisting ZnSSiO _2, Ga ₂ Te ₃ first upper protective layer 5nm consisting, Ag ₁ In ₇ Sb ₇₀ consists Te ₂₂ recording layer 10 nm, the second lower protective consisting Ga ₂ Te ₃ Layer 5nm, ZnSS
A first lower protective layer made of iO ₂ was formed in the order of 30 nm by a sputtering apparatus, and a polycarbonate film having a thickness of 80 μm was pasted through a double-sided pressure-sensitive adhesive sheet having a thickness of 20 μm to prepare a phase change type information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

(Examples 30 to 36) In Example 29, in Example 30, the first upper protective layer was made of Ag ₁₉ Sb ₂₉ Te ₅₂ ,
In Example 31, Ga ₂ Te ₃ was used for the second lower protective layer. In Example 31, Ag ₁₉ Sb ₂₉ Te ₅₂ was used for the first upper protective layer. In ₂ Te ₃ was used for the second lower protective layer. In Example 32, the first upper protective layer was used. In ₂ Te ₃ for the protective layer, Ga ₂ Te ₃ for the second lower protective layer, and in Example 33, In ₂ T ₃ for the first upper protective layer
e ₃ , In ₂ Te ₃ for the second lower protective layer.
Ga ₂ Te ₃ in the upper protective layer, an an In ₂ Te ₃ in the second lower protective layer, AgSbSe ₂ Example first upper protective layer at 35, a Ga ₂ Te ₃ to the second lower protective layer, in Example 36 AgSbSe for the first upper protective layer
₂ and Example 29 except that In ₂ Te ₃ was used for the second lower protective layer.
In the same manner as in the above, a phase change type information recording medium was obtained.

(Experimental Example 2 (Comparative Example)) On a polycarbonate substrate having a diameter of 12 cm, a thickness of 1.1 mm, and a tracking guide formed by continuous grooves on the surface thereof, a reflective heat radiation layer made of Ag and a _second layer made of ZnSSiO ₂ were formed on a polycarbonate substrate. Upper protective layer 5 nm,
First upper protective layer 60 nm of Ga ₂ Te _3, recording layer 10 nm of Ag ₁ In ₇ Sb ₇₀ Te ₂₂ , lower protective layer 30 of ZnSSiO ₂
In the order of nm, a film is formed by a sputtering device,
A polycarbonate film having a thickness of 80 μm was attached via a double-sided pressure-sensitive adhesive sheet having a thickness of μm to prepare a phase-change information recording medium. Next, the recording layer of the disk was initialized by an initialization device having a large-diameter semiconductor laser.

Comparative Example 3 A phase change type information recording medium was obtained in the same manner as in Experimental Example 2 except that the first upper protective layer was not provided. Each created medium was recorded under the following conditions. Laser wavelength 407nm NA = 0.85 linear velocity
13m / s Track pitch 0.30μm Recording at linear density 0.13μm / bit, linear density 0.20μm
The jitter at the time of recording at / bit and recording 100 times at a linear density of 0.20 μm / bit was measured. Table 2 shows the results.

As shown in Table 2, in the embodiment having a protective layer having low thermal conductivity between the recording layer and the reflective heat radiation layer, 4 mW
In the example having a protective layer having a small thermal conductivity between the recording layer and the light transmitting layer, a linear density of 0.13 μm was obtained.
Even at a high recording density of m / bit, a jitter of the order of 7% could be obtained.

[0052]

[Table 2]

[0053]

According to the present invention, a phase change type information recording medium having a high recording density and excellent recording sensitivity can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a configuration example of a phase change type information recording medium according to the present invention.

FIG. 2 is a schematic sectional view showing a configuration example of a phase change type information recording medium according to the present invention.

FIG. 3 is a schematic sectional view showing a configuration example of a phase change type information recording medium according to the present invention.

FIG. 4 is a schematic sectional view showing a configuration example of a phase change type information recording medium according to the present invention.

FIG. 5 is a schematic sectional view showing a configuration example of a phase change type information recording medium according to the present invention.

FIG. 6 is a diagram showing a predicted heat distribution in a recording layer portion when AIN is used for a lower protective layer.

FIG. 7 is an estimated heat distribution diagram of a recording layer portion when ZnSSiO ₂ is used for a lower protective layer.

FIG. 8 is a predicted heat distribution diagram of a recording layer portion when Ga ₂ Te ₃ is used for a lower protective layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Lower protective layer 3 Recording layer 4 Upper protective layer 5 Reflection / radiation layer 6 Overcoat layer 7 Light transmission layer 8 Hard coat layer

Claims (15)

[Claims] 1. An optical information recording medium using a phase change material as a recording layer, at least a light transmitting layer, a lower protective layer, a recording layer, a first upper protective layer, and a second upper protective layer from the side where laser light is incident. A phase change type information recording medium, wherein the first upper protective layer has a thermal conductivity of 10 mW / cmK or less. 2. The method according to claim 1, wherein the first upper protective layer is made of Ag ₁₉ Sb ₂₉ Te ₅₂ , In ₂ T
_2. The phase change type information recording medium according to claim 1, comprising at least one selected from e ₃ , Ga ₂ Te ₃ and AgSbSe ₂ . 3. The phase change type information recording medium according to claim 1, wherein the thickness of the first upper protective layer is 1 to 50 nm. 4. In an optical information recording medium having a recording layer made of a phase change material, at least a light transmitting layer, a lower protective layer, a recording layer, an upper protective layer, and a reflective heat dissipation layer are laminated in this order from the side where laser light is incident. And the thermal conductivity of the upper protective layer is 10 mW
A phase change type information recording medium characterized by being at most / cmK. 5. The phase-change information recording medium according to claim 4, wherein the upper protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ . 6. The phase-change information recording medium according to claim 4, wherein the thickness of the upper protective layer is 1 to 50 nm. 7. An optical information recording medium using a phase change material as a recording layer, at least a light transmitting layer, a first lower protective layer, a second lower protective layer, a recording layer, and an upper protective layer from the side where laser light is incident. A phase change type information recording medium, wherein the layer and the reflective heat dissipation layer are laminated in this order, and the thermal conductivity of the second lower protective layer is 10 mW / cmK or less. 8. The phase change type information recording medium according to claim 7, wherein the second lower protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ . 9. The phase change type information recording medium according to claim 7, wherein the thickness of the second lower protective layer is 1 to 50 nm. 10. In an optical information recording medium having a recording layer made of a phase change material, at least a light transmitting layer, a lower protective layer, a recording layer, an upper protective layer, and a reflective heat dissipation layer are laminated in this order from the side where laser light is incident. And the thermal conductivity of the lower protective layer is 10
A phase change type information recording medium characterized by being at most mW / cmK. 11. The phase-change information recording medium according to claim 10, wherein the lower protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ . 12. The phase change type information recording medium according to claim 10, wherein the lower protective layer has a thickness of 1 to 50 nm. 13. An optical information recording medium using a phase-change material as a recording layer, wherein at least a light transmitting layer, a first lower protective layer, a second lower protective layer, a recording layer, a first layer, and a second layer from the side where laser light is incident. Phase change type information characterized by laminating an upper protective layer, a second upper protective layer, and a reflective heat dissipation layer in this order, wherein the second lower protective layer and the first upper protective layer have a thermal conductivity of 10 mW / cmK or less. recoding media. 14. The second lower protective layer is made of at least one selected from In ₂ Te ₃ and Ga ₂ Te ₃ , and the first upper protective layer is made of Ag ₁₉ Sb ₂₉ Te ₅₂ , In ₂ Te ₃ , Ga ₂ Te ₃ and a phase-change information recording medium according to claim 13 comprising at least one selected from among AgSbSe _2. 15. The phase change type information recording medium according to claim 13, wherein the thicknesses of the second lower protective layer and the first upper protective layer are 1 to 50 nm.