JPH11176022A - Phase change optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear recording density with a narrow track pitch, a small difference in recording sensitivity between a land portion and a groove portion in land and groove recording, a good radial contrast, and an initialization. Provided is a phase-change optical recording medium having excellent uniformity of the crystallization state of a land portion and a groove portion. SOLUTION: A first protective layer 1 on a substrate having a guide groove.
0, a recording layer 20 on the first protective layer, a second protective layer 30 on the recording layer, a reflective heat dissipation layer 100 on the second protective layer, and the guide groove depth 1b is larger than the thickness of the second protective layer. In a large phase change optical recording medium, the width 1a of the land portion of the guide groove is 500 nm or less, and the reflective heat radiation layer is made of Ag, Au, Cu, or an alloy having these elements as a base material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recording and reproducing information by causing an optical change in a recording layer material by irradiating a light beam such as a phase-change optical recording disk.
The present invention also relates to a rewritable phase change optical recording medium.

[0002]

2. Description of the Related Art As one of optical recording media capable of recording, reproducing and erasing information by irradiating a laser beam, a so-called phase-change optical recording medium utilizing a transition between a crystal and an amorphous phase or between a crystal and a crystal phase. Is well known.
It can be overwritten with a single beam,
Since the optical system on the drive side is simpler, it is used as a recording medium for computer related and video / audio. GeTe, GeTeS
e, GeTeS, GeSeS, GeSeSb, GeAs
Se, InTe, SeTe, SeAs, Ge-Te-
(Sn, u, Pd), GeTeSeSb, GeTeS
b, Ag-In-Sb-Te and the like are known. In particular, Ag-In-Sb-Te is highly sensitive, has a clear amorphous (non-crystalline) portion, and has a clear recording layer for mark edge recording. (Japanese Unexamined Patent Publication No. 2-37)
466, JP-A-2-171325, JP-A-2-415581, JP-A-4-141485, etc.).

The reflective heat dissipation layer greatly contributes to the recording density and sensitivity of these phase-change optical recording media, improvement of various characteristics such as repetitive recording characteristics and repetitive reproduction characteristics in response to a wide range of linear recording speeds. That is, the complex refractive index of the reflective heat dissipation layer has an effect on optical characteristics such as modulation and reflectance, and the thermal conductivity has a strong effect on recording sensitivity, repetitive reproduction characteristics, recording density, and the like. In particular, in high-density recording, increasing the thermal conductivity of the reflective heat dissipation layer is particularly important in improving the linear recording density. Au or an Au alloy having a relatively large thermal conductivity has been used for an optical recording medium such as a CD-R as a reflective heat radiation layer which is excellent in that it has high corrosion resistance and high thermal conductivity. Ag, which has the largest thermal conductivity as a metal element, has a problem in corrosion resistance such as sulfurization, but should be used as a reflective heat dissipation layer by improving the corrosion resistance by alloying such as adding Au or Pd. Can be. Further, as disclosed in Japanese Patent Application Laid-Open No. 7-201075, it has been proposed to use a write-once optical recording medium as a two-layer structure with an Al reflective heat dissipation layer having excellent corrosion resistance.

However, in a rewritable optical recording medium such as a DVD-RW which requires a high repetitive recording characteristic, a high recording density can be obtained when Ag or an Ag alloy is used for the reflective heat dissipation layer. The challenge was to improve the repetitive recording characteristics. In addition, when an Au or Ag alloy is used for the reflective heat dissipation layer, the adhesion to the protective layer is poor, and thermal shock due to crystallization during initialization and repetitive recording, or mechanical shock during the bonding process or use. As a result, partial peeling is likely to occur, and recording at the peeled portion becomes impossible, which causes a problem in reliability.

On the other hand, Al or Al alloys such as Al-Ti and Al-Si, which are excellent in repetitive recording characteristics and cost, have relatively high thermal conductivity and relatively low recording density such as CD-RW. It is used as a reflective heat radiation layer of an optical recording medium. However, there is a certain limit in improving the linear recording density, and there has been a problem in improving the linear recording density. Further, when the track pitch is narrow, especially when the width of the land portion is narrow, and when the reflection heat radiation layer on the groove portion is located in front of the recording layer on the land portion with respect to the light incident surface, In the case of an optical recording medium having a guide groove with a groove depth greater than the thickness of the second protective layer existing between the heat dissipation layer and the second protection layer, before the incident light reaches the recording layer on the land due to the diffraction of light. However, there is a problem that a part of the power is absorbed by the reflection heat radiation layer on the groove portion, and the effective power density is reduced. This is particularly remarkable in Al having a relatively large light absorption coefficient, which has caused a difference in recording sensitivity between the land and the groove.

In the method of initializing an optical recording medium in which light is incident from a substrate surface, a land portion and a groove portion have
Non-uniformity occurred in the initial crystallization state, which had an adverse effect on radial contrast, initial recording characteristics, and the like. Further, in the phase change optical recording medium, there is recording unevenness due to the difference in the light absorptivity between the amorphous portion and the crystallized portion. Although an absorption control-phase difference control layer made of Si or the like has been formed between the layers, Si or the like has a relatively low thermal conductivity, and there has been a problem in improving the linear recording density.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve such a problem, to achieve a high linear recording density at a narrow track pitch, and a difference in recording sensitivity between a land portion and a groove portion in land and groove recording. Another object of the present invention is to provide a phase-change optical recording medium having a good radial contrast, excellent in uniformity of the crystallized state of the land portion and the groove portion even at the time of initialization. Further, an object of the present invention is to provide a phase change optical recording medium in which the reflective heat dissipation layer and the protective layer are prevented from peeling off due to thermal shock or the like accompanying initialization or repeated recording, have excellent repeated recording characteristics, and have high reliability. Is to do. Another object of the present invention is to provide a phase-change optical recording medium having good reflectivity and modulation.

[0008]

According to the present invention, first, a first protective layer on a substrate having a guide groove, a recording layer on the first protective layer, a second protective layer on the recording layer, (2) In a phase-change optical recording medium having a reflective heat radiation layer on a protective layer and a guide groove depth greater than the film thickness of the second protective layer, the width of the land portion of the guide groove is 500 nm or less, and the reflective heat radiation layer is Ag, Au, Cu
Alternatively, there is provided a phase-change optical recording medium comprising an alloy containing these elements as a base material. Secondly, there is provided a phase-change optical recording medium according to the first aspect, characterized in that the phase-change optical recording medium further comprises an adhesive layer between the second protective layer and the reflective heat dissipation layer. Third, a first protection layer on a substrate having a guide groove, a recording layer on the first protection layer, a second protection layer on the recording layer, a reflective heat dissipation layer on the second protection layer, and a guide groove depth In the phase change optical recording medium whose thickness is larger than the thickness of the second protective layer, the first reflective heat dissipation layer made of Ag, Au, Cu or an alloy having these elements as a base material on the second protective layer, It has a second reflective heat radiation layer on the heat radiation layer, and the absolute value of the real part and / or the imaginary part of the complex refractive index of the second reflective heat radiation layer is the real part and / or the imaginary part of the complex refractive index of the first reflective heat radiation layer. And the thickness of the first reflective heat dissipation layer is 5 to 5
0 nm and the width of the land portion of the guide groove is 50
A phase change optical recording medium characterized by having a thickness of 0 nm or less is provided. Fourthly, there is provided a phase-change optical recording medium according to the third aspect, further comprising an adhesive layer between the second protective layer and the first reflective heat dissipation layer. Fifth, the phase-change optical recording medium according to the third or fourth aspect, further comprising a reflection correction layer between the first reflective heat-radiating layer and the second reflective heat-radiating layer. Is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. FIG. 1 is an enlarged sectional view schematically showing one example of the phase change optical recording medium of the present invention. 1, a first protective layer 10 is provided on a substrate 1 having a guide groove, a recording layer 20 is provided on the first protective layer 10, a second protective layer 30 is provided on the recording layer 20, and a second protective layer 30 is provided on the second protective layer 30. A reflective heat radiation layer 100 made of Ag, Au, Cu or an alloy containing these elements as a base material is formed, the width 1a of the land portion of the guide groove is 500 nm or less, and the depth 1b of the guide groove is The relationship is larger than the thickness of the two protective layers 30. An environmental protection layer 60 made of, for example, a UV resin may be formed on the reflective heat radiation layer 100.

According to the present invention, there is provided a first protective layer on a substrate having a guide groove, a recording layer on the first protective layer, a second protective layer on the recording layer, and a reflective heat radiation layer on the second protective layer. In a phase change optical recording medium having a guide groove depth larger than the thickness of the second protective layer, Ag, Au, Cu or an alloy having these elements as a base material is used for the reflective heat dissipation layer, and the land portion of the guide groove is used. Is smaller than the recording wavelength by 500 nm or less, the recording density is high, the difference in recording sensitivity between land and groove in land & groove recording is small, good radial contrast is obtained, and initialization is also possible. A phase change optical recording medium having excellent uniformity of the crystallization state of the land portion and the groove portion can be obtained.

[0011] This is because a phase change optical recording medium in which the depth of the guide groove is larger than the thickness of the second protective layer, that is, the reflection heat radiation layer on the groove portion is larger than the recording layer on the land portion with respect to the light incident surface. In the optical recording medium existing on the front surface, the reflective heat radiation layer close to the recording layer is made of Ag, Au, Cu, or an alloy having these elements as a base material, which has a high thermal conductivity and a relatively small light absorption coefficient. This prevents part of the incident light from being scattered or absorbed by the reflective heat dissipation layer on the groove before reaching the recording layer on the land due to the effect of light diffraction. Is reduced, and unevenness of the incident light intensity (incident from the substrate surface) at the position of the recording layer existing on the land portion and the groove portion can be reduced.

[0012] Thereby, it is possible to improve the initializing characteristics of a phase change optical recording medium using a light source such as a high-output large-aperture LD beam with high productivity or a flash lamp.
The difference in the initial crystallinity between the recording layer on the land portion and the recording layer on the groove portion can be eliminated, and an appropriate radial contrast can be maintained. Such an effect is more remarkable as the guide groove depth of the substrate is larger.

As the substrate 1, a transparent material such as a resin such as polycarbonate or glass can be used, and the substrate 1 has a guide groove for tracking servo. As the first protective layer 10 and the second protective layer 30, Zn
A known dielectric such as S.SiO ₂ or AlN can be used, and has a predetermined refractive index.

As the recording layer 20, a conventionally known phase-change optical recording material can be used, for example, GeTe,
GeTeSe, GeTeS, GeSeS, GeSeS
b, GeAsSe, InTe, SeTe, SeAs, G
e-Te- (Sn, Au, Pd), GeTeSeSb,
It is appropriately selected from GeTeSb, Ag-In-Sb-Te and the like in consideration of the recording linear velocity, the recording method, the density, and the like.

The reflective heat dissipation layer is made of Ag, Au, Cu or an alloy having these elements as a base material, for example, Au-Ag, A
u-Cu, Au-Ag-Cu, Ag-Cu and the like, and these alloys are known additional elements, for example,
Pd, Pt, Al, Ge, Sn, Ti, In, Te, S
It may contain b, Zn, Mg or the like. However, the composition range is a range in which a predetermined high thermal conductivity is maintained.

FIG. 2 is an enlarged sectional view schematically showing another example of the phase-change optical recording medium of the present invention. In the phase-change optical recording medium shown in FIG. 10
0 has an adhesive layer 101. As the adhesive layer 101, the heat conductivity or the complex refractive index is a reflection heat dissipation layer or a second heat dissipation layer.
It is similar to the material of the protective layer.
A material that contributes to improving the adhesion to the protective layer 30 is preferable,
For example, Pd, Pt, Cu, Cu alloy, Au-Cu-based alloy, ZnO and the like are preferably used.

Note that Au or A is used as a base material of the reflective heat radiation layer.
When a material having relatively poor adhesion such as a u alloy is used, Cu, a Cu alloy, Ag, an Ag alloy, or the like may be used as the adhesive layer. In this case, the reflection heat radiation layer has a multilayer structure. The thickness of the adhesive layer is preferably about 20 nm or less as long as a sufficient adhesive strength can be obtained. By providing an adhesive layer between the second protective layer and the reflective heat radiating layer, the adhesion between the second protective layer and the reflective heat radiative layer is improved, and film peeling can be prevented, and the recording characteristics are excellent. A highly reliable phase change optical recording medium can be obtained.

FIG. 3 is an enlarged sectional view schematically showing another example of the phase change optical recording medium of the present invention. 3, a first protective layer 10 is provided on a substrate 1 having a guide groove, a recording layer 20 is provided on the first protective layer 10, and a second protective layer 3 is provided on the recording layer 20.
0, the first reflective heat dissipation layer 40 made of Ag, Au, Cu or an alloy having these elements as a base material on the second protection layer 30
And a reflective heat radiation layer 100 comprising a second reflective heat radiation layer 50 on the first reflective heat radiation layer 40, and the absolute value of the real part and / or the imaginary part of the complex refractive index of the second reflective heat radiation layer is the first.
The absolute value of the real part and / or the imaginary part of the complex refractive index of the reflective heat dissipation layer is different from that of the first heat dissipation layer.
nm, and the width 1a of the land portion of the guide groove is 500
nm or less, and the depth 1b of the guide groove is
The relationship is larger than the film thickness.

With such a configuration, the recording density is high, the difference in recording sensitivity between the land and the groove in land and groove recording is small, good radial contrast is obtained, and the land portion is initialized. Thus, it is possible to obtain a phase change optical recording medium having excellent uniformity of the crystallized state of the groove portion and further having excellent reflectance and modulation.

This is because (1) the phase change optical recording medium in which the depth of the guide groove is larger than the thickness of the second protective layer, that is, the reflection heat radiation layer on the groove portion is formed on the land portion with respect to the light incident surface. In the optical recording medium located in front of the recording layer, the first reflective heat dissipation layer adjacent to the recording layer is formed by using Ag, Au, Cu, or these elements having a high thermal conductivity and a relatively small light absorption coefficient as a base material. By configuring with an alloy that does, the incident light is prevented from being partially absorbed by the reflective heat dissipation layer on the groove before reaching the recording layer on the land due to the diffraction of light,
The effective power density can be prevented from lowering, and the nonuniformity of the incident light intensity (incident from the substrate surface) at the position of the recording layer existing on the land and the groove can be reduced. And (2) providing a second reflective heat dissipation layer on the first reflective heat dissipation layer to promote heat dissipation of the first reflective heat dissipation layer, and further, at an interface between the first reflective heat dissipation layer and the second reflective heat dissipation layer. The absolute value of the real part and / or the imaginary part of the complex refractive index of each reflective heat radiation layer is made different so that the reflection of the incident light affects the optical characteristics, and the film thickness range of the first reflective heat radiation layer is 5 to 5. By setting the thickness to 50 nm, the phase and amplitude of the return light can be changed without changing the thickness of the second protective layer, and both the thermal characteristics and the optical characteristics can be improved.

The effect as described in the above (1) is obtained when the depth of the guide groove of the substrate is large, the light absorption coefficient of the second reflective heat dissipation layer is large (when Al or the like is used), Is particularly remarkable as the depth increases. In the case where only this function is required to be achieved, the thickness of the first reflective heat dissipation layer made of Ag or an Ag alloy may be set to exceed 50 nm.

Further, the non-uniformity of the incident light intensity (incident from the substrate surface) at the position of the recording layer existing on the land portion and the groove portion can be reduced, so that a high-output large-diameter high productivity can be achieved. The initialization characteristics of a phase change optical recording medium using a light source such as an LD beam or a flash lamp can be improved, and the difference in the initial crystallinity between the recording layer on the land and the recording layer on the groove can be eliminated. Also, an appropriate radial contrast can be maintained. Further, by providing the second reflective heat radiation layer on the first reflective heat radiation layer, the heat radiation of the first reflective heat radiation layer is promoted, the mechanical strength of the reflective heat radiation layer is improved, and the repetitive recording characteristics are improved. be able to.

The first reflective heat dissipation layer is made of Ag, Au, Cu or an alloy having these elements as a base material, for example, Au-A
g, Au-Cu, Au-Ag-Cu, Ag-Cu, etc., and these alloys are known additional elements such as Pd, Pt, Al, Ge, Sn, Ti, In, T
e, Sb, Zn, Mg, etc. may be included. However, the composition range is a range in which a predetermined high thermal conductivity is maintained. As the second reflective heat dissipation layer, a known metal, for example,
Al, Sn, Pt, Pd, Pb, or an alloy thereof, for example, Al-Si, Al-Ti, Pb-Sn, or the like can be used. Such a second reflective heat dissipation layer is
At the reproduction wavelength, it has a complex refractive index different from that of the first reflective heat dissipation layer.

The thickness of the first reflective heat radiation layer is 5 to 50 n.
m, and the thickness of the second reflective heat dissipation layer is 50 to 300.
The range of nm is preferred. This is because the first reflective heat dissipation layer and the second
The light reflection at the boundary with the reflective heat dissipation layer is in a film thickness range that affects the phase and amplitude of the reflected light. In the case of ultra-high density recording using a short wavelength laser having a wavelength of less than 600 nm, A
The difference in the complex refractive index between g and Cu or Au is remarkable,
The material of the second reflective heat dissipation layer may be Ag, Au, Cu, or an alloy thereof. For example, there are cases where the first reflective heat dissipation layer is made of Au and the second reflective heat dissipation layer is made of Ag, or where the first reflection heat dissipation layer is made of Ag and the second reflection heat dissipation layer is made of Au.

Furthermore, by providing an adhesive layer between the first reflective heat radiation layer and the second protective layer, the adhesion between the second protective layer and the first reflective heat radiation layer is improved, and peeling of the film is prevented. As a result, it is possible to obtain a phase change optical recording medium having excellent repetitive recording characteristics and high reliability. As the adhesive layer, a material having a thermal conductivity or a complex refractive index similar to that of the material of the first reflective heat dissipation layer or the second protective layer, and a material contributing to the improvement of the adhesion between the first reflective heat dissipation layer and the second protective layer is used. Preferably, for example, Pd, Pt,
Cu, Cu alloy, Au-Cu based alloy, ZnO and the like are preferably used.

The base material of the first reflective heat dissipation layer is Au.
When a material having relatively low adhesion such as Au or Au alloy is used, Cu, Cu alloy, Ag, Ag alloy or the like may be used as the adhesive layer. In this case, the first reflective heat dissipation layer has a multilayer structure. The thickness of the adhesive layer is preferably about 20 nm or less as long as a sufficient adhesive strength can be obtained.

FIG. 4 is an enlarged sectional view schematically showing another example of the phase-change optical recording medium of the present invention. In the phase-change optical recording medium shown in FIG. The reflection correction layer 45 is provided between the reflection and heat dissipation layer 50. It is preferable that the complex refractive index of the reflection correction layer 45 has a value different from that of the first reflection and heat dissipation layer and the second reflection and heat dissipation layer. As the reflection correction layer, for example, Ge, Si, C, Sb, Te or the like can be used. By providing the reflection correction layer 45 between the first reflection heat dissipation layer 40 and the second reflection heat dissipation layer 50,
The amplitude and phase of the reflected light reflected at the interface between the first reflective heat dissipation layer 40 and the second reflection heat dissipation layer 50 can be corrected to optimize modulation and reflectivity, or to improve DPD characteristics.

[0028]

The present invention will be described below in more detail with reference to examples.

Example 1 A track pitch of 740 nm, a land width of 450 nm,
A first protective layer of ZnS.SiO _{2 with} a thickness of 150 nm, a recording layer of Ge—Sb—Te with a thickness of 20 nm, and a ZnS.ZnO.SiO ₂ layer on a polycarbonate substrate having a guide groove with a groove depth of 70 nm. A second protective layer having a thickness of 20 nm and a reflective heat radiation layer having a thickness of 100 nm made of Ag are sequentially formed, and an environmental protection layer made of a UV resin is applied on the reflective heat radiation layer by spin coating to obtain a phase-change optical recording medium. Was. In this phase-change optical recording medium, since a recording laser beam is incident from the substrate side, the recording layer of the land portion is viewed from the direction of travel of the laser beam from the relationship between the depth of the guide groove and the thickness of the second protective layer. (20a in FIG. 1) is a reflective heat radiation layer in the groove portion (40 in FIG. 1).
It will be present behind the end face of a). This phase change optical recording medium is 100 μm in length, 2 μm in width, and 900 m in output.
When the semiconductor laser beam of W was used for initialization at an initialization linear velocity of 3 m / s, initialization with excellent uniformity of the crystallization state of the land and the groove could be performed. When recording was performed on this phase-change optical recording medium with a laser beam having a wavelength of 635 nm, it was possible to perform recording with a high linear recording density and a small difference in recording sensitivity between land and groove portions in land & groove recording. Also, it had good radial contrast.

Example 2 A track pitch of 740 nm, a land width of 450 nm,
A first protective layer of ZnS.SiO _{2 with} a thickness of 150 nm, a recording layer of Ge—Sb—Te with a thickness of 20 nm, and a ZnS.ZnO.SiO ₂ layer on a polycarbonate substrate having a guide groove with a groove depth of 70 nm. A 20 nm-thick second protective layer, a 10 nm-thick adhesive layer made of ZnO, and a 100 nm-thick reflective heat dissipation layer are sequentially formed, and an environmental protection layer made of a UV resin is spin-coated on the reflection heat dissipation layer. By coating, a phase change optical recording medium was obtained. The complex refractive index of ZnO is close to the complex refractive index of the second protective layer, and the reflection of light at the interface between the adhesive layer and the second protective layer is relatively small. This phase-change optical recording medium is 100 μm long and 2 μm wide.
Initialization was performed at a linear velocity of 3 m / s with a semiconductor laser beam having an output power of 900 mW and a reflective heat radiation layer and the second protective layer, which were not peeled off due to thermal shock caused by the initialization and repeated recording. The recording characteristics were excellent.

Example 3 A track pitch of 550 nm, a land width of 320 nm,
The first protective layer having a thickness of 120nm composed of ZnS · SiO ₂ on a polycarbonate substrate having a guide groove depth 40 nm, the recording layer having a thickness of 5nm consisting Ag-In-Sb-Te, ZnS · ZnO · SiO 2 13nm thick
Second protective layer, a first reflective heat radiation layer made of Au and having a thickness of 30 nm, and a second reflective heat radiation layer made of an Al alloy and having a thickness of 100 nm are sequentially formed, and an environmental protection made of UV resin is formed on the second reflective heat radiation layer. The layer was applied by spin coating to obtain a phase change optical recording medium. In this phase-change optical recording medium, since a recording laser beam is incident from the substrate side, the recording layer of the land portion is viewed from the direction of travel of the laser beam from the relationship between the depth of the guide groove and the thickness of the second protective layer. (FIG. 3
20a) is the first reflective heat dissipation layer in the groove portion (FIG. 3).
At the end of 40a). This phase change optical recording medium is 100 μm long and 2 μm wide.
Initialization was performed at a linear velocity of 3 m / s using a semiconductor laser beam having an output power of 900 mW and m, and initialization with excellent uniformity of the crystallization state of the land portion and the groove portion could be performed. The phase change optical recording medium has a wavelength of 500 nm.
As a result, recording was performed with a high linear recording density, a small difference in recording sensitivity between the land portion and the groove portion in land and groove recording, and a good radial contrast. Further, the reflectance of the unrecorded portion and the recorded portion was measured with a reproduction laser beam having a wavelength of 500 nm, and the modulation was calculated. As a result, the reflectance of the unrecorded portion was 20%, and the modulation was 71%. Next, in the above phase change optical recording medium, a phase change optical recording medium was prepared in the same manner except that the first reflective heat radiation layer was not provided, and was produced in the same manner except that the thickness of the first reflective heat radiation layer was 5 nm. Phase change optical recording medium, first
A phase change optical recording medium manufactured in the same manner except that the thickness of the reflective heat dissipation layer was set to 14 nm, and the thickness of the first reflective heat dissipation layer was set to 50
The thickness of the phase change optical recording medium and the first reflective heat radiation layer produced in the same manner except that the thickness of the first reflection and heat radiation layer was changed to 100 nm. For a phase change optical recording medium produced in the same manner except that the thickness was changed to 200 nm, the reflectance of the unrecorded portion and the recorded portion was measured in the same manner as above, and the modulation was calculated. Table 1 shows the relationship between the heat radiation layer thickness and the heat radiation layer thickness.

[0032]

[Table 1]

As is clear from Table 1, when the first reflective heat radiation layer is not provided, that is, when the reflective layer is made of only Al, the reflectance is relatively high at 49%, but the modulation is 32.
%, The thickness of the first reflective heat radiation layer is sufficiently thick as 100 nm, and the modulation is as high as 82% in the film thickness region where the influence of the second reflective heat radiation layer does not affect the optical characteristics, but the reflectance is 13%. In the case where the thickness of the first reflective heat radiation layer is 5 to 50 nm,
The reflected light at the interface between the first reflective heat dissipation layer and the second reflective heat dissipation layer affects the optical characteristics, and a phase change optical recording medium having both appropriate reflectivity and modulation can be obtained.

Example 4 A track pitch of 550 nm, a land width of 320 nm,
The first protective layer having a thickness of 120nm composed of ZnS · SiO ₂ on a polycarbonate substrate having a guide groove depth 40 nm, the recording layer having a thickness of 5nm consisting Ag-In-Sb-Te, ZnS · ZnO · SiO 2 13nm thick
A second protective layer, a 10 nm thick adhesive layer made of ZnO,
30 nm thick first reflective heat dissipation layer made of Au and Al
A second reflective heat radiation layer having a thickness of 100 nm made of an alloy was sequentially formed, and an environmental protection layer composed of a UV resin was applied on the second reflection heat radiation layer by spin coating to obtain a phase-change optical recording medium. This phase-change optical recording medium is 100 μm long and 2 μm wide.
Initialization was performed at a linear velocity of 3 m / s using a semiconductor laser beam having a power of 900 mW and a power of 900 mW. As a result, there was no peeling between the first reflective heat radiation layer and the second protective layer due to thermal shock caused by the initialization and repeated recording. And excellent repetitive recording characteristics.

Example 5 A track pitch of 740 nm, a land width of 420 nm,
A first protective layer of ZnS.SiO ₂ having a thickness of 160 nm, a recording layer of Ag-In-Sb-Te having a thickness of 5 nm, and a ZnS.ZnO.SiO ₂ layer formed on a polycarbonate substrate having a guide groove having a groove depth of 70 nm. 20 nm thick
Second protective layer, a first reflective heat dissipation layer made of Ag, having a thickness of 20 nm, a reflection correction layer made of Ge, having a thickness of 10 nm, and a second reflection heat dissipation layer made of an Al alloy having a thickness of 100 nm, are sequentially formed. (2) An environmental protection layer made of a UV resin was applied on the reflective heat dissipation layer by spin coating to obtain a phase-change optical recording medium. This phase-change optical recording medium has a length of 100 μm,
Initialization was performed with a semiconductor laser beam having a width of 2 μm and an output of 900 mW at an initial linear velocity of 3 m / s. As a result, initialization with excellent uniformity of the crystallization state of the land and the groove could be performed. In addition, a wavelength of 6
When recording was performed with a laser beam of 35 nm, linear recording density was high, and recording with little difference in recording sensitivity between land and groove in land & groove recording could be performed, and good radial contrast was obtained. . The reflectance of the unrecorded portion and the recorded portion was measured with a reproducing laser beam having a wavelength of 635 nm, and the modulation was calculated. As a result, the reflectance of the unrecorded portion was 19% and the modulation was 53%. Next, in the above-mentioned phase change optical recording medium, a phase change optical recording medium produced in the same manner except that the reflection correction layer is not provided, and the thickness of the reflection correction layer is set to 20 nm.
With respect to a phase-change optical recording medium manufactured in the same manner as above, the reflectance of the unrecorded portion and the recorded portion was measured in the same manner as above, and the modulation was calculated. Dependency) is shown in Table 2.

[0036]

[Table 2]

As is clear from Table 2, the reflectance and the modulation can be adjusted by providing the reflection correction layer between the first reflection heat radiation layer and the second reflection heat radiation layer.

[0038]

According to the present invention, the linear recording density is high at a narrow track pitch, the difference in recording sensitivity between land and groove in land and groove recording is small, good radial contrast is obtained, and initialization is performed. In this case, the recording layer in the land portion is also easily initialized, and a phase-change optical recording medium having excellent uniformity of the crystallization state in the land portion and the groove portion can be obtained. Further, according to the present invention, peeling of the reflective heat dissipation layer and the protective layer due to thermal shock or the like accompanying initialization or repeated recording is prevented, and a phase change optical recording medium having excellent repeated recording characteristics and high reliability is obtained. be able to. Further, according to the present invention, a phase-change optical recording medium having good reflectivity and modulation can be obtained.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view schematically showing an example of a phase change optical recording medium of the present invention.

FIG. 2 is an enlarged sectional view schematically showing another example of the phase change optical recording medium of the present invention.

FIG. 3 is an enlarged sectional view schematically showing another example of the phase change optical recording medium of the present invention.

FIG. 4 is an enlarged sectional view schematically showing another example of the phase change optical recording medium of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 10 1st protective layer 20 recording layer 30 2nd protective layer 40 1st reflective heat dissipation layer 45 reflection correction layer 50 2nd reflective heat dissipation layer 60 environmental protection layer 100 reflection heat dissipation layer 101 adhesive layer

Claims (5)

[Claims] 1. A guide groove having a first protective layer on a substrate having a guide groove, a recording layer on the first protective layer, a second protective layer on the recording layer, and a reflective heat dissipation layer on the second protective layer. In a phase change optical recording medium having a depth greater than the thickness of the second protective layer, the width of the land portion of the guide groove is 500 nm or less, and the reflective heat radiation layer is made of Ag,
A phase change optical recording medium comprising Au, Cu, or an alloy containing these elements as a base material. 2. The phase-change optical recording medium according to claim 1, further comprising an adhesive layer between the second protective layer and the reflection heat radiation layer. 3. A guide groove having a first protective layer on a substrate having a guide groove, a recording layer on the first protective layer, a second protective layer on the recording layer, and a reflective heat dissipation layer on the second protective layer. In a phase change optical recording medium having a depth greater than the thickness of the second protective layer, the first reflective heat dissipation layer made of Ag, Au, Cu, or an alloy having these elements as a base material on the second protective layer; It has a second reflective heat radiation layer on the reflective heat radiation layer, and the absolute value of the real part and / or the imaginary part of the complex refractive index of the second reflective heat radiation layer is the real part of the complex refractive index of the first reflective heat radiation layer and / or Different from the absolute value of the imaginary part,
A phase-change optical recording medium, wherein the thickness of the first reflective heat dissipation layer is in the range of 5 to 50 nm, and the width of the land portion of the guide groove is 500 nm or less. 4. The phase-change optical recording medium according to claim 3, further comprising an adhesive layer between the second protective layer and the first reflective heat radiation layer. 5. The phase change optical recording medium according to claim 3, further comprising a reflection correction layer between the first reflective heat radiation layer and the second reflective heat radiation layer.