JP2006209840A - Optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical recording medium provided with a plurality of information layers layered via at least a transparent intermediate layer, wherein data can be recorded and recorded data can be reproduced desirably in any information layer even when the plurality of information layers except the furthest information layer from a light incident surface of a laser beam include recording films formed by using a phase transition material of an Sb eutectic system. <P>SOLUTION: In the optical recording medium provided with the plurality of information layers layered on a supporting substrate via at least the transparent intermediate layer, at least one information layer of the plurality of information layers except the furthest information layer from the light incident surface of the laser beam, includes a recording film 34 formed by using the phase transition material of the Sb eutectic system, a reflection film 32 provided on the supporting substrate 11 side of the recording film 34 and a dielectric film 31 provided on the supporting substrate 11 side of the reflection film 32. The dielectric film 31 is formed by using a dielectric material having a refractive index of 2.0 to 2.4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical recording medium. More specifically, the present invention includes a plurality of information layers stacked on a support substrate through at least a transparent intermediate layer. When an information layer other than the information layer farthest from the light incident surface includes a recording film formed of an Sb eutectic phase change material, data is recorded in any information layer as desired. In addition, the present invention relates to an optical recording medium capable of reproducing recorded data.

  Conventionally, optical recording media represented by CD and DVD have been widely used as recording media for recording digital data, and recorded data can be rewritten as CD-RW or DVD-RW. Such rewritable optical recording media are known.

  In order to increase the recording capacity of these optical recording media, a technique for increasing the number of information layers and increasing the area of the recording area has been developed. A rewritable optical recording medium having a plurality of information layers Has been proposed.

  In these rewritable optical recording media, generally, the power of a laser beam applied to an information layer including a recording film formed of a phase change material corresponds to recording power Pw, base power Pb, and erasing power Pe. By modulating to a plurality of levels, data can be recorded on the information layer, and the recorded data can be reproduced or erased.

  However, the rewritable optical recording medium having a plurality of information layers records data on the information layer by irradiating one of the information layers with a laser beam, reproduces the recorded data, or Since it is configured to be erased, data is recorded on the information layer far from the light incident surface, and data recorded on the information layer far from the light incident surface is reproduced or erased. A laser beam is irradiated to the information layer far from the light incident surface through the information layer close to the surface.

  Therefore, in order to record data in an information layer far from the light incident surface and reproduce or erase data recorded in the information layer far from the light incident surface, information close to the light incident surface is desired. It is necessary that the layer has a high light transmittance for the laser beam.

  Here, in order to increase the light transmittance of the information layer, it is effective to provide the information layer with a dielectric film formed of a dielectric material on the support substrate side with respect to the reflective film. In particular, it is considered that it is effective to form such a dielectric film with a dielectric material having a large refractive index.

Based on this idea, an optical recording medium provided with a dielectric film formed of a dielectric material having a large refractive index on the support substrate side with respect to the reflective film on the information layer close to the light incident surface, for example, A first substrate constituting a light incident surface on which a laser beam is incident, a second substrate disposed so as to face the first substrate, a first substrate, and a second substrate. A first information layer disposed between, a second information layer disposed between the first information layer and the second substrate, a first information layer and a second information layer, The first information layer has a refractive index of 2.3 or more with respect to light having a wavelength of 390 nm to 430 nm from the second substrate side toward the first substrate side. A third dielectric layer, a first reflective layer, a second dielectric layer, Ge, Sn, Sb and Te A first recording layer containing, include optical recording medium, characterized in that it comprises a first dielectric layer (JP 2003-16687 (Patent Document 1) reference.).
JP 2003-16687 A

  As described in Japanese Patent Application Laid-Open No. 2003-16687, as a phase change material for forming a recording film included in an information layer of a rewritable optical recording medium, a periodic table such as a chalcogenide compound has been conventionally used. A phase change material having a compound composition containing a group 16 element (O, S, Se, Te and Po) has been widely used, but in recent years, a phase change material having an Sb eutectic composition (Sb eutectic phase change). And an optical recording medium having an information layer including a recording film formed of such a phase change material is being put into practical use (for example, Japanese Patent Application Laid-Open No. 2003-341240).

  However, in order to increase the light transmittance of the information layer close to the light incident surface as in the optical recording medium described in Japanese Patent Laid-Open No. 2003-16687, the information layer close to the light incident surface is When it is necessary to provide a dielectric film formed of a dielectric material having a large refractive index on the support substrate side, the recording film included in the information layer is formed of an Sb eutectic phase change material. When data is recorded on the information layer close to the light incident surface and the recorded data is reproduced, the jitter of the reproduced signal sometimes deteriorates.

  Therefore, in an optical recording medium provided with a plurality of information layers, the optical transparency and recording characteristics of an information layer provided at a position close to the light incident surface, including a recording film formed of an Sb eutectic phase change material By improving both, it is difficult to record data in any information layer as desired and to reproduce the recorded data.

  Accordingly, an object of the present invention is to provide a plurality of information layers stacked on a support substrate via at least a transparent intermediate layer, and among the plurality of information layers, other than the information layer farthest from the light incident surface of the laser beam When the information layer includes a recording film formed of a Sb eutectic phase change material, data is recorded on any information layer as desired, and the recorded data is reproduced. It is an object of the present invention to provide an optical recording medium that can be used.

  As a result of intensive studies in order to achieve the above object of the present invention, the present inventor has found that, in an optical recording medium having a plurality of information layers, of the plurality of information layers, the furthest from the laser beam incident surface At least one information layer other than the information layer includes a recording film formed of an Sb eutectic phase change material, a reflective film provided on the support substrate side with respect to the recording film, and a reflective film On the other hand, when a dielectric film provided on the support substrate side is included, when the dielectric film is formed of a dielectric material having a refractive index of 2.0 to 2.4, the information layer When the data is recorded on the information layer and the recorded data is reproduced, the jitter of the reproduction signal can be prevented from deteriorating from the light incident surface of the laser beam. Of information layers other than the farthest information layer It found that it is possible to achieve both light transmitting and recording characteristics of one information layer at a high level even without.

  The present invention is based on such knowledge. According to the present invention, the object of the present invention includes a plurality of information layers stacked on a support substrate through at least a transparent intermediate layer. And at least one information layer other than the information layer farthest from the light incident surface of the laser beam is a recording film formed of an Sb eutectic phase change material, and the recording film A reflective film provided on the support substrate side, and a dielectric film provided on the support substrate side with respect to the reflective film, wherein the dielectric film has a refractive index of 2.0 to 2. This is achieved by an optical recording medium characterized by being formed of four dielectric materials.

  Further, as a result of further earnest research, the present inventor has found that at least one information layer other than the information layer farthest from the light incident surface of the laser beam is formed of a Sb eutectic phase change material. A film, a reflective film provided on the support substrate side with respect to the recording film, and a dielectric film provided with two or more films provided on the support substrate side with respect to the reflective film, Of these two or more films, when at least the thickest film is formed of a dielectric material having a refractive index of 2.0 to 2.4, other than the information layer farthest from the light incident surface of the laser beam It has been found that it is possible to achieve a high level of both the light transmission and recording characteristics of at least one information layer.

  Therefore, the object of the present invention is also provided with a plurality of information layers stacked on a support substrate through at least a transparent intermediate layer, and the farthest from the light incident surface of the laser beam among the plurality of information layers. A recording film in which at least one information layer other than the information layer is formed of an Sb eutectic phase change material; a reflective film provided on the support substrate side with respect to the recording film; And a dielectric film provided on the support substrate side with respect to the reflective film, the film having the largest thickness among the two or more films having a refractive index of 2.0. Or an optical recording medium characterized by being formed by a dielectric material of 2.4.

  In the present invention, the refractive index means a refractive index with respect to a laser beam having a wavelength of 380 nm to 450 nm.

  In the present invention, a dielectric film formed of a dielectric material having a refractive index of 2.0 to 2.4 or a film constituting the dielectric film is a dielectric film or a dielectric film formed of a dielectric material. It is also included that the film constituting the film has a refractive index of 2.0 to 2.4.

  According to the present invention, since the light transmittance and recording characteristics of at least one information layer other than the information layer farthest from the light incident surface of the laser beam can be made compatible at a high level, As desired, it is possible to record data and to reproduce the recorded data, and to minimize a decrease in the light amount of the laser beam when the laser beam passes through the information layer. Therefore, by irradiating a laser beam through the information layer to the information layer provided at a position farther from the light incident surface than the information layer, the information layer is also subjected to data as desired. Can be recorded, and the recorded data can be reproduced or erased.

  In the present invention, when the dielectric film provided on the support substrate side has two or more films with respect to the reflective film, at least the film having the largest film thickness among the two or more films. If the refractive index is formed of a dielectric material having a refractive index of 2.0 to 2.4, the refractive index of the dielectric material for forming a film other than the thickest film is not particularly limited. For example, all of the two or more films can be formed of a dielectric material having a refractive index of 2.0 to 2.4.

  In the present invention, the refractive index of the dielectric material is preferably 2.1 to 2.4, and particularly preferably 2.1 to 2.3. In the case where the dielectric film is formed of a dielectric material having a refractive index of 2.1 to 2.4, it is possible to achieve both light transmittance and recording characteristics at a higher level.

In the present invention, the dielectric material having a refractive index of 2.0 to 2.4 is not particularly limited. For example, a mixture of ZnS and SiO ₂ having a molar ratio of about 85:15 to about 60:40. A mixture of ZrO ₂ and Cr ₂ O _{3 in} a molar ratio of about 95: 5 to about 70:30, a mixture of ZrO ₂ and Y ₂ O _{3 in} a molar ratio of about 98: 2 to about 90:10, ZnO, CeO ₂ , Ta ₂ O ₅ , Nb ₂ O _{5 and the} like are preferably used.

  In the present invention, the Sb eutectic phase change material is not particularly limited, but an Sb eutectic phase change material containing Sb as a main component is preferably used, and Sb, Sb and eutectic are used. A phase change material containing at least one of the elements as a main component is more preferably used.

  Here, the element having an eutectic with Sb is not particularly limited as long as it can have an eutectic with Sb. For example, Ge, Mg, Ga, As, Pb, Bi, Cr, Mn Ni, Cu, Zn, Pd, Ag, In, and other elements are preferably used.

  Among such Sb eutectic phase change materials, a phase change material containing 79 atom% to 95 atom% Sb and 5 atom% to 21 atom% Ge, and 70 atom% to 95 atom% Particularly preferred is a phase change material comprising Sb, a Ge of greater than 0 atomic percent and less than 30 atomic percent, and a Mg content of greater than 0 atomic percent and less than 25 atomic percent. When a recording film is formed of such a phase change material, after the data recorded in the information layer including the recording film is stored at a high temperature for a long period of time, the data is changed to a desired data by new data. In addition, direct overwriting can be performed and storage characteristics can be improved.

  In the present invention, the Sb eutectic phase change material may further contain elements other than Sb and elements having eutectic with Sb.

  According to the present invention, a support substrate is provided with a plurality of information layers stacked through at least a transparent intermediate layer, and information other than the information layer farthest from the light incident surface of the laser beam among the plurality of information layers. In the case where the layer includes a recording film formed of an Sb eutectic phase change material, data can be recorded and reproduced in any information layer as desired. It is possible to provide an optical recording medium that can be used.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a partially cutaway schematic perspective view showing an optical recording medium according to a preferred embodiment of the present invention, and FIG. 2 is a schematic enlarged sectional view of a portion indicated by A in FIG.

  As shown in FIG. 1, the optical recording medium 10 according to this embodiment is formed in a disc shape, and has an outer diameter of about 120 mm and a thickness of about 1.2 mm.

  The optical recording medium 10 according to the present embodiment is configured as a rewritable optical recording medium, and as shown in FIG. 2, a support substrate 11, a transparent intermediate layer 12, a light transmission layer 13, a support substrate 11, and the like. The L0 information layer 20 provided between the transparent intermediate layer 12 and the L1 information layer 30 provided between the transparent intermediate layer 12 and the light transmission layer 13 are provided. A light incident surface 13a on which the laser beam L is incident is configured.

  In this embodiment, the L0 information layer 20 constitutes an information layer far from the light incident surface 13a, and the L1 information layer 30 constitutes an information layer close to the light incident surface 13a.

  The optical recording medium 10 according to this embodiment is an objective lens (FIG. 2) in which a laser beam L having a wavelength λ of 380 nm to 450 nm has a numerical aperture NA of about 0.85 from the direction indicated by the arrow L in FIG. The light transmitting layer 13 is configured to be irradiated via a not-shown).

  The support substrate 11 functions as a support for ensuring the mechanical strength required for the optical recording medium 10.

  The material for forming the support substrate 11 is not particularly limited as long as it can function as a support for the optical recording medium 10, but a resin is preferably used. Such a resin is particularly preferably a polycarbonate resin or a polyolefin resin from the viewpoint of processability, optical characteristics, and the like. In this embodiment, the support substrate 11 is formed of a polycarbonate resin.

  In the present embodiment, the support substrate 11 has a thickness of about 1.1 mm.

  In the present embodiment, the laser beam L is irradiated through the light transmission layer 13 located on the side opposite to the support substrate 11, so that the support substrate 11 does not necessarily have optical transparency. Not necessary.

  As shown in FIG. 2, the support substrate 11 has a groove 11a formed on the surface thereof. The groove 11a serves as a guide track for the laser beam L when data is recorded on the L0 information layer 20 and data is reproduced from the L0 information layer 20.

  The support base 11 having the groove 11a on the surface is produced by, for example, an injection molding method using a stamper (not shown).

  The transparent intermediate layer 12 has a function of separating the L0 information layer 20 and the L1 information layer 30 physically and optically with a sufficient distance.

  As shown in FIG. 2, a groove 12 a is formed on the surface of the transparent intermediate layer 12. The groove 12a formed on the surface of the transparent intermediate layer 12 functions as a guide track for the laser beam L when data is recorded on the L1 information layer 30 and data is reproduced from the L1 information layer 30.

  The transparent intermediate layer 12 needs to have a sufficiently high light transmittance since the laser beam L passes when data is recorded on the L0 information layer 20 and data is reproduced from the L0 information layer 20. . Therefore, the material for forming the transparent intermediate layer 12 is required to have little optical absorption and reflection in the near-infrared to ultraviolet wavelength region and a small birefringence. The material for forming the transparent intermediate layer 12 is not particularly limited as long as it satisfies these conditions, but an ultraviolet curable resin composition containing an ultraviolet curable resin such as an ultraviolet curable acrylic resin. It is preferable that the transparent intermediate layer 12 is formed by an object.

  The transparent intermediate layer 12 is formed by applying a solution of an ultraviolet curable resin composition on the L0 information layer 20 by a spin coating method to form a coating film, and preparing the support substrate 11 on the surface of the coating film. It is preferably formed by irradiating with ultraviolet rays through a stamper in a state of covering a stamper (not shown) on which a concave and convex pattern similar to the stamper used in the above is formed.

  The light transmission layer 13 is a layer through which the laser beam L is transmitted, and a light incident surface 13a is constituted by one surface thereof.

  The material for forming the light transmission layer 13 is required to have low absorption and a low birefringence in the near-infrared to ultraviolet wavelength region. The material for forming the light transmission layer 13 is not particularly limited as long as the material satisfies these conditions, but a resin composition containing an ultraviolet curable resin, an electron beam curable resin, or the like may be used. In order to form the light transmission layer 13, a resin composition containing an ultraviolet curable acrylic resin is more preferably used.

  The light transmission layer 13 is preferably formed to have a thickness of 30 μm to 200 μm.

  The light transmission layer 13 is preferably formed by applying a solution of the resin composition on the surface of the L1 information layer 30 by spin coating, but the sheet formed of the light transmission resin is bonded. The light transmission layer 13 can also be formed by adhering to the surface of the L1 information layer 30 using an agent.

  FIG. 3 is a schematic enlarged cross-sectional view of the L0 information layer 20.

  As shown in FIG. 3, in this embodiment, the L0 information layer 20 includes the reflective film 21, the second dielectric film 22, the L0 recording film 23, and the first dielectric film 24 from the support substrate 11 side. In addition, the heat dissipation film 25 is laminated.

  The reflective film 21 reflects the laser beam L applied to the L0 recording film 23 via the light transmitting layer 13 and the L1 information layer 30 and emits the light again from the light transmitting layer 13. Is used to effectively dissipate heat generated in the L0 recording film 23.

  The material for forming the reflective film 21 is not particularly limited, and Mg, Al, Ti, Cr, Fe, Co, Ni, Cu, Zn, Ge, Ag, Pt, Au, Nd, and the like are used. However, among these, metal materials such as Al, Au, Ag, Cu, or an alloy containing at least one of these metals, such as Al, Au, Ag, Cu, or an alloy of Ag and Cu, which have high reflectivity, are reflective. It is preferably used for forming the film 21. In particular, when the reflective film 21 contains Ag, the reflective film 21 having excellent surface smoothness can be formed, and the noise level of the reproduction signal can be reduced, which is preferable.

  The reflective film 21 may be configured by a single film or may be configured by stacking two or more films. In this embodiment, the reflective film 21 is formed by a metal material containing Ag. The first film 212 and the second film 211 are laminated.

  The thickness of the reflective film 21 is not particularly limited, but is preferably 10 nm to 300 nm, and particularly preferably 40 nm to 200 nm.

  The reflective film 21 is formed by, for example, a sputtering method.

  The second dielectric film 22 and the first dielectric film 24 physically and chemically protect the L0 recording film 23, dissipate the heat generated in the L0 recording film 23, and further, the laser beam L Has a function of increasing the change in optical properties before and after irradiation.

  The material for forming the second dielectric film 22 and the first dielectric film 24 is not particularly limited as long as it is a transparent dielectric material in the wavelength region of 380 nm to 450 nm that is the wavelength region of the laser beam L. Although not intended, the second dielectric film 22 and the first dielectric film 24 are made of Si, Zn, Al, Ta, Ti, Co, Zr, Pb, Ag, Sn, Ca, Ce, V, Cu. It is preferably formed from an oxide, nitride, sulfide, carbide, fluoride, or composite containing at least one metal selected from the group consisting of Fe, Mg.

Each of the second dielectric film 22 and the first dielectric film 24 may be configured by a single film or may be configured by stacking two or more films. In this embodiment, The second dielectric film 22 is configured by laminating a first film 222 formed of a mixture of ZnS and SiO ₂ and a second film 221 formed of an oxide of Ce and Al. The first dielectric film 24 is constituted by a single film.

  The thickness of the second dielectric film 22 and the first dielectric film 24 is not particularly limited, but the thickness of the second dielectric film 22 is preferably 5 nm to 35 nm. The thickness of one dielectric film 24 is preferably 10 nm to 80 nm.

  The second dielectric film 22 and the first dielectric film 24 are formed by, for example, a sputtering method.

  The L0 recording film 23 is a film for recording data by forming recording marks, is formed of a phase change material, and is formed of a single film. Since the phase change material has a reflectance different from that in the crystalline state and the reflectance in the amorphous state, data is recorded by using this, and the recorded data is reproduced.

  The phase change material for forming the L0 recording film 23 is not particularly limited, but the L0 recording film 23 is at least one element selected from the group consisting of Sb, Te, Ge, Ag, Tb and Mn. It is preferably formed including a phase change material containing

  The thickness of the L0 recording film 23 is not particularly limited, but is preferably 8 nm to 25 nm.

  The L0 recording film 23 is formed by, for example, a sputtering method.

  The heat dissipation film 25 plays a role of radiating heat transferred from the L0 recording film 23 via the first dielectric film 24.

The material for forming the heat dissipation film 25 is not particularly limited as long as it has high light transmittance with respect to the laser beam L and can radiate the heat generated in the recording film 23. A material having a thermal conductivity higher than the thermal conductivity of the first dielectric film 24 is preferable. Specifically, AlN, Al ₂ O ₃ , SiN, ZnS, ZnO, SiO _2, etc. are used as the heat dissipation film 25. Preferably used for forming.

  The heat dissipation film 25 is preferably formed to have a thickness of 10 nm to 120 nm.

  The heat dissipation film 25 is formed by, for example, a sputtering method.

  FIG. 4 is a schematic enlarged cross-sectional view of the L1 information layer 30.

  As shown in FIG. 4, in the present embodiment, the L1 information layer 30 includes the fourth dielectric film 31, the reflective film 32, the third dielectric film 33, and the L1 recording film 34 from the support substrate 11 side. The second dielectric film 35, the first dielectric film 36, and the heat dissipation film 37 are laminated.

  The fourth dielectric film 31 plays a role of achieving both the light transmittance and the recording characteristics of the L1 information layer 30 at a high level. Furthermore, the L1 recording film 34 is irradiated with the laser beam L together with the reflection film 32 described later. It effectively serves to dissipate the heat generated in

  The fourth dielectric film 31 may be configured by a single film or may be configured by stacking two or more films, but in the present embodiment, the first film 312 and the first film A second film 311 having a thickness larger than that of the film 312 is laminated and configured.

The material for forming the second film 311 is not particularly limited as long as it is a dielectric material having a refractive index of 2.0 to 2.4. Ti, Zr, Hf, Ta, Si, Al A dielectric material such as an oxide, nitride, sulfide, carbide, fluoride, or a composite thereof containing at least one metal selected from the group consisting of Mg, Y, Ce, Zn, Cr and Nb , Used to form the second film 311. Among these, a mixture of ZnS and SiO ₂ having a molar ratio of about 85:15 to about 60:40, a mixture of ZrO ₂ and Cr ₂ O ₃ having a molar ratio of about 95: 5 to about 70:30, and a molar ratio of A mixture of about 98: 2 to about 90:10 ZrO ₂ and Y ₂ O ₃ , ZnO, CeO ₂ , Ta ₂ O ₅ , Nb ₂ O _5, etc. is preferably used to form the second film 311. In the present embodiment, the second film 311 is formed of a mixture of ZnS and SiO ₂ having a molar ratio of 80:20. When the second film 311 is formed of such a material, it is possible to achieve both the light transmittance and the recording characteristics of the L1 information layer 30 at a high level.

The material for forming the first film 312 is not particularly limited, and at least one metal selected from the group consisting of Ti, Zr, Hf, Ta, Si, Al, Mg, Y, Ce, and Zn. Dielectric materials such as oxides, nitrides, carbides, fluorides, or composites containing these are used to form the first film 312 but dielectric materials that do not contain S are preferred. Used. When the first film 312 provided adjacent to the reflection film 32 described later is formed of such a dielectric material, the surface of the reflection film 32 containing Ag can be prevented from being corroded. And high storage reliability can be ensured. In the present embodiment, the first film 312 is formed of a mixture of ZrO ₂ and Y ₂ O ₃ having a molar ratio of 97: 3. When the first film 312 is formed of such a material, the heat generated in the L1 recording film 34 can be quickly dissipated by the irradiation of the laser beam L, and high storage reliability is achieved. It becomes possible to secure.

  The fourth dielectric film 31 is preferably formed to have a thickness of 3 nm to 30 nm. When the thickness of the fourth dielectric film 31 is less than 3 nm, the heat dissipation effect is reduced. On the other hand, when it exceeds 30 nm, the productivity is reduced.

  In the present embodiment, the thicknesses of the first film 312 and the second film 311 are particularly limited as long as the second film 311 is set to be thicker than the first film 312. Is not to be done.

  The first film 312 and the second film 311 are each formed by, for example, a sputtering method.

  The reflection film 32 reflects the laser beam L applied to the L1 recording film 34 via the light transmission layer 13 and emits the laser beam L from the light transmission layer 13 again, and is irradiated with the laser beam L. Thus, the heat generated in the L1 recording film 34 is effectively dissipated.

  The material for forming the reflective film 32 is not particularly limited, but the same metal material as the metal material preferably used for forming the reflective film 21 of the L0 information layer 20 shown in FIG. Are preferably used. In the present embodiment, the reflective film 32 is formed of a metal material containing Ag as a main component. When the reflective film 32 is formed of such a metal material, the surface smoothness of the reflective film 32 is excellent, and the noise level of the reproduction signal can be reduced.

  The reflective film 32 is preferably formed so as to have a thickness of 5 nm to 25 nm, and particularly preferably formed so as to have a thickness of 10 nm to 15 nm. When the reflective film 32 is formed to have a thickness of 5 nm to 25 nm, the heat dissipation from the reflective film 32 can be improved and the light transmittance of the L1 information layer 30 can be improved. it can.

  The reflective film 32 is formed by, for example, a sputtering method.

  The third dielectric film 33, together with the second dielectric film 35, plays a role of physically and chemically protecting the L1 recording film 34, and is generated in the L1 recording film 34 by the irradiation of the laser beam L. It has a function of radiating heat to the reflective film 32 side.

The material for forming the third dielectric film 33 is not particularly limited, and the same material as that for forming the first film 312 is used. In the present embodiment, the third dielectric film 33 is formed of a mixture of ZrO ₂ and Y ₂ O ₃ having a molar ratio of 97: 3, like the first film 312. When the third dielectric film 33 is formed of such a material, it is possible to quickly dissipate the heat generated in the L1 recording film 34 by irradiation with the laser beam L.

  The third dielectric film 33 is preferably formed to have a thickness of 3 nm to 15 nm. When the thickness of the third dielectric film 33 is less than 3 nm, it is difficult to form the third dielectric film 33 as a continuous film. On the other hand, when the thickness exceeds 15 nm, L1 It becomes difficult to effectively release the heat of the recording film 34 to the reflection film.

  The third dielectric film 33 is formed by, for example, a sputtering method.

  The L1 recording film 34 is a film for recording data by forming recording marks, is formed of an Sb eutectic phase change material, and is formed of a single film. Since the phase change material has a different reflectance in a crystalline state and a reflectance in an amorphous state, data is recorded using this, and the recorded data is reproduced.

  The Sb eutectic phase change material for forming the L1 recording film 34 is not particularly limited, but includes a phase change material containing Sb and at least one element having an eutectic with Sb as main components. In particular, a phase change material comprising 79 atomic% to 95 atomic% Sb and 5 atomic% to 21 atomic% Ge, and 70 atomic% to 95 atomic% Sb and 0 atomic% Preferably, a phase change material containing less than 30 atomic% Ge and more than 0 atomic% and not more than 25 atomic% Mg is preferably used. In this embodiment, the L1 recording film 34 is formed of a phase change material containing 79 atomic% to 95 atomic% of Sb and 5 atomic% to 21 atomic% of Ge. When the L1 recording film 34 is formed of such a phase change material, the storage characteristics of the L1 information layer 30 are improved regardless of the film thickness of the L1 recording film 34.

  The L1 recording film 34 is preferably formed to have a thickness of 2 nm to 15 nm, and more preferably 4 nm to 9 nm. When the L1 recording film 34 is formed to have a thickness of 2 nm to 15 nm, the storage characteristics of the L1 information layer 30 are further improved.

  The L1 recording film 34 can be formed by, for example, a vapor phase growth method using a chemical species containing a constituent element of the L1 recording film 34. Examples of the vapor phase growth method include a vacuum evaporation method and a sputtering method, but it is preferable to form the L1 recording film 34 by a sputtering method.

  The second dielectric film 35, together with the third dielectric film 33, plays a role of physically and chemically protecting the L1 recording film 34, and is generated in the L1 recording film 34 by the irradiation of the laser beam L. It has a function of radiating heat to the heat radiating film 37 described later. The second dielectric film 35 also serves as a barrier film that prevents the elements constituting the first dielectric film 36 from diffusing into the L1 recording film 34.

The material for forming the second dielectric film 35 is not particularly limited, and the same material as that for forming the first film 312 and the third dielectric film 33 is used. In this embodiment, the second dielectric film 35 is formed of a mixture of ZrO ₂ and Y ₂ O ₃ having a molar ratio of 97: 3, like the first film 312 and the third dielectric film 33. ing. When the second dielectric film 35 is formed of such a material, the heat generated in the L1 recording film 34 by the irradiation of the laser beam L can be quickly dissipated.

  The second dielectric film 35 is preferably formed to have a thickness of 3 nm to 15 nm. When the thickness of the second dielectric film 35 is less than 3 nm, it becomes difficult to sufficiently fulfill the role as a barrier film, and the heat dissipation effect is reduced, while it exceeds 15 nm. In the case where the second dielectric film 35 is formed, the internal stress generated when the second dielectric film 35 is formed is increased, and the second dielectric film 35 is easily cracked.

  The second dielectric film 35 is formed by, for example, a sputtering method.

  The first dielectric film 36 has a function of improving the adhesion between the second dielectric film 35 and the heat dissipation film 37.

The material for forming the first dielectric film 36 is a material having high light transmittance with respect to the laser beam L and having high adhesion to the second dielectric film 35 and the heat dissipation film 37. The first dielectric film 36 is preferably formed from a mixture of ZnS and SiO ₂ , although not particularly limited. The first dielectric film 36, in the case of forming a mixture of ZnS and SiO _2, the molar ratio of ZnS and SiO ₂ is 60: 40 to 95: is preferably 5. When the ZnS molar ratio is less than 60%, the refractive index of the first dielectric film 36 is lowered, and the region of the L1 recording film 34 where the recording mark is formed and the recording mark is not formed. There is a possibility that the difference in reflectance from the area of the L1 recording film 34 is lowered. On the other hand, when the molar ratio of ZnS exceeds 95%, it is difficult to form the first dielectric film 36 as a complete transparent film, and there are adverse effects such as a decrease in signal output. Come on.

  The first dielectric film 36 is preferably formed to have a thickness of 5 nm to 50 nm. If the thickness of the first dielectric film 36 is less than 5 nm, cracks are likely to occur in the heat dissipation film 37, and if it exceeds 50 nm, the heat dissipation effect may be reduced.

  The first dielectric film 36 is formed by, for example, a sputtering method.

  The heat dissipation film 37 plays a role of radiating heat transferred from the L1 recording film 34 via the second dielectric film 35 and the first dielectric film 36.

The material for forming the heat dissipation film 37 is not particularly limited as long as it has high light transmittance with respect to the laser beam L and can dissipate heat generated in the L1 recording film 34. Specifically, materials having a thermal conductivity higher than that of the second dielectric film 35, specifically, AlN, Al ₂ O ₃ , SiN, ZnS, ZnO, SiO _{2 and the} like are preferably used.

  The heat dissipation film 37 is preferably formed to have a thickness of 20 nm to 70 nm. If the thickness of the heat dissipation film 37 is less than 20 nm, a sufficient heat dissipation effect may not be obtained. On the other hand, if it exceeds 70 nm, it takes a long time to form the heat dissipation film 37. The productivity of the optical recording medium 10 may be reduced.

  The heat dissipation film 37 is formed by, for example, a sputtering method.

  When data is recorded on the L0 information layer 20 or the L1 information layer 30 of the optical recording medium 10 according to this embodiment configured as described above, the power is between the recording power Pw and the base power Pb. When the modulated laser beam L reproduces the data recorded in the L0 information layer 20 or the L1 information layer 30, the laser beam L whose power is set to the reproduction power Pr is changed to the light transmission layer 13. Then, the L0 recording film 23 included in the L0 information layer 20 or the L1 recording film 34 included in the L1 information layer 30 is focused.

  When recording marks are formed on the L1 recording film 34 included in the L1 information layer 30 of the optical recording medium 10 and data is recorded on the L1 information layer 30, a laser beam whose power is set to the recording power Pw. L is irradiated onto the L1 recording film 34, and the region of the L1 recording film 34 irradiated with the laser beam L is heated to a temperature equal to or higher than the melting point of the phase change material, and the phase change material contained in the region is melted. The Next, the laser beam L whose power is set to the base power Pb is irradiated to the L1 recording film 34 through the light transmission layer 13, and the power is melted by the laser beam L whose power is set to the recording power Pw. The phase change material is rapidly cooled, the phase change material changes from a crystalline state to an amorphous state, a recording mark is formed on the L1 recording film 34, and data is recorded on the L1 information layer 30.

In this embodiment, the L1 information layer 30 is formed of an Sb eutectic phase change material containing 79 atomic% to 95 atomic% Sb and 5 atomic% to 21 atomic% Ge. 34, and the first film 312 and the first film 312 which are provided on the support substrate 11 side with respect to the reflective film 32 and are formed of a mixture of ZrO ₂ and Y ₂ O ₃ having a molar ratio of 97: 3. A fourth dielectric film 31 formed by laminating a second film 311 formed of a mixture of ZnS and SiO ₂ having a refractive index of 2.0 to 2.4 and a refractive index of 2.0 to 2.4. And the second dielectric film 35 and the third dielectric film 33 are both formed of a mixture of ZrO ₂ and Y ₂ O ₃ with a molar ratio of 97: 3. , L1 information layer 30 has high light transmission and recording characteristics. It is possible to achieve both at a level, because it is possible to improve heat dissipation, the L1 information layer 30, as desired, it is possible to record the data.

  On the other hand, when reproducing data recorded on the L1 information layer 30 of the optical recording medium 10, the laser beam L whose power is set to the reproduction power Pr is transmitted through the light transmission layer 13 to the L1 information layer 30. The amount of the laser beam L focused on the L1 recording film 34 and reflected by the reflective film 32 or the like is detected.

  In the present embodiment, as described above, the L1 information layer 30 can be made to have both the light transmittance and the recording characteristics at a high level, and the heat dissipation can be improved. The data recorded in 30 can be reproduced as desired.

  On the other hand, when recording marks are formed on the L0 recording film 23 included in the L0 information layer 20 of the optical recording medium 10 and data is recorded on the L0 information layer 20, the power becomes the recording power Pw. The set laser beam L is applied to the L0 recording film 23 via the light transmission layer 13 and the L1 information layer 30, and the region of the L0 recording film 23 irradiated with the laser beam L is equal to or higher than the melting point of the phase change material. And the phase change material contained in the region is melted. Next, the laser beam L whose power is set to the base power Pb is irradiated to the L0 recording film 23 via the light transmission layer 13 and the L1 information layer 30, and the laser beam whose power is set to the base power Pb. By L, the melted phase change material is rapidly cooled, the phase change material changes from a crystalline state to an amorphous state, a recording mark is formed on the L0 recording film 23, and data is recorded on the L0 information layer 20.

  In the present embodiment, as described above, the light transmittance of the L1 information layer 30 can be sufficiently improved. Therefore, when the laser beam L passes through the L1 information layer 30, the amount of light of the laser beam L is reduced. Therefore, by irradiating the L0 information layer 20 with the laser beam L through the L1 information layer 30, data can be transferred to the L0 information layer 20 as desired. It becomes possible to record.

  On the other hand, when data recorded on the L0 information layer 20 of the optical recording medium 10 is reproduced, the laser beam L whose power is set to the reproduction power Pr is transmitted through the light transmission layer 13 and the L1 information layer 30. The light quantity of the laser beam L focused on the L0 recording film 23 included in the L0 information layer 20 and reflected by the reflecting film 21 or the like is detected.

  In the present embodiment, as described above, when the laser beam L passes through the L1 information layer 30, it is possible to minimize a decrease in the light amount of the laser beam L. Then, by irradiating the L0 information layer 20 with the laser beam L, the data recorded in the L0 information layer 20 can be reproduced as desired.

  Examples are given below to clarify the effects of the present invention.

Example 1
Optical recording medium sample # 1 was produced as follows.

  First, a polycarbonate substrate having a thickness of 1.1 mm, a diameter of 120 mm, and grooves formed on the surface with a groove pitch of 0.32 μm was manufactured by an injection molding method.

Next, the polycarbonate substrate is set in a sputtering apparatus, and is composed of 98.4 atomic% Ag, 0.7 atomic% Nd, 0.9 atomic% Cu and N on the surface of the polycarbonate substrate where the groove is formed. Consists of a second film having a thickness of 40 nm and a first film having a thickness of 60 nm made of 98.4 atomic% Ag, 0.7 atomic% Nd and 0.9 atomic% Cu. A second reflecting film having a thickness of 10 nm made of a mixture of CeO ₂ and Al ₂ O ₃ with a molar ratio of 80:20 and a mixture of ZnS and SiO ₂ with a molar ratio of 50:50. A second dielectric film composed of a first film having a thickness of 10 nm, comprising 77.1 atomic% Sb, 18.7 atomic% Te and 4.2 atomic% Ge. A phase change material containing as a main component, Wherein L0 recording film having a thickness of 0 nm, the molar ratio of the mixture of ZnS and SiO ₂ of 80:20 as the main component, wherein the first dielectric film having a thickness of 40 nm, and the AlN as a main component A heat dissipation film having a thickness of 30 nm was sequentially formed by sputtering to form an L0 information layer.

  Here, the first film constituting the reflective film, the first film and the second film constituting the second dielectric film, the L0 recording film and the first dielectric film are in an argon gas atmosphere. It formed by the sputtering method using the target which has a composition corresponding to each film | membrane.

  On the other hand, the second film and the heat dissipating film constituting the reflective film were formed by reactive sputtering in an argon and nitrogen gas atmosphere using an AgNdCu or Al target, respectively.

  Next, the polycarbonate substrate on which the L0 information layer is formed is set in a spin coater, a solution of an ultraviolet curable acrylic resin composition is applied on the L0 information layer, and a groove is formed on the transparent substrate. The UV curable acrylic resin composition is cured by irradiating ultraviolet rays while developing the UV curable acrylic resin composition solution while rotating the polycarbonate substrate and rotating the polycarbonate substrate, and has a thickness of 25 μm. An intermediate layer was formed. The groove formed in the transparent intermediate layer had a groove pitch of 0.32 μm.

  Further, using a semiconductor laser having a wavelength of 810 nm, the L0 recording film was initialized at an output of 500 mW to crystallize the L0 recording film.

Next, the polycarbonate substrate on which the L0 information layer and the transparent intermediate layer were formed was set in a sputtering apparatus, and a mixture of ZnS and SiO ₂ having a molar ratio of 80:20 (refractive index = 2.20) on the surface of the transparent intermediate layer. 26) as a main component, a first film having a thickness of 15 nm, and a first film having a thickness of 4 nm including a mixture of ZrO ₂ and Y ₂ O ₃ having a molar ratio of 97: 3 as a main component. A fourth dielectric film composed of the following film: an alloy composed of 98 atomic% Ag, 1 atomic% Pd and 1 atomic% Cu, and having a thickness of 15 nm, a molar ratio of 97 A third dielectric film containing a mixture of ₃ ZrO ₂ and Y ₂ O ₃ as a main component and having a thickness of 6 nm, containing 87.0 atomic% Sb and 13.0 atomic% Ge 6nm thickness with phase change material as main component L1 recording film having a molar ratio of 97: comprises 3 a mixture of ZrO ₂ and _Y 2 _{O 3} as a main component, a second dielectric layer, ZnS and SiO molar ratio 80:20, having a thickness of 6nm _A first dielectric film having a mixture of ₂ as a main component and having a thickness of 12.5 nm, and a heat dissipation film having AlN as a main component and having a thickness of 35 nm are sequentially formed by a sputtering method. The L1 information layer was formed.

  Here, the heat dissipation film was formed by reactive sputtering using an Al target in an atmosphere of argon gas and nitrogen gas.

  Furthermore, a first film and a second film, a reflective film, a third dielectric film, an L1 recording film, a second dielectric film, and a first dielectric film constituting the fourth dielectric film Was formed by a sputtering method using a target having a composition corresponding to each film in an argon gas atmosphere.

  Next, on the surface of the heat dissipation film of the L1 information layer, a solution of an ultraviolet curable acrylic resin composition is applied by a spin coating method to form a coating film, and the coating film is irradiated with ultraviolet rays. The curable acrylic resin composition was cured to form a light transmission layer having a thickness of 75 μm.

  Further, using a semiconductor laser having a wavelength of 810 nm, the L1 recording film was initialized at an output of 500 mW to crystallize the L1 recording film.

  Thus, an optical recording medium sample # 1 was produced.

Next, a second film constituting a fourth dielectric film containing a mixture of ZrO ₂ and SiO ₂ having a molar ratio of 85:15 (refractive index = 2.14) as a main component and having a thickness of 16 nm is formed. An optical recording medium sample # 2 was produced in the same manner as the optical recording medium sample # 1 except for the points formed.

Furthermore, a second film constituting a fourth dielectric film containing a mixture of ZrO ₂ and SiO ₂ having a molar ratio of 70:30 (refractive index = 2.03) as a main component and having a thickness of 16 nm is provided. An optical recording medium sample # 3 was produced in the same manner as the optical recording medium sample # 1 except for the points formed.

Then, the molar ratio of 97: comprises 3 a mixture of ZrO ₂ and _Y 2 _{O 3} as a main component without forming a first film having a thickness of 4 nm, the molar ratio of the ZrO ₂ 90:10 An optical recording medium sample except that a single film constituting a fourth dielectric film containing a mixture of Cr ₂ O ₃ (refractive index = 2.28) as a main component and having a thickness of 20 nm is formed. Optical recording medium sample # 4 was produced in the same manner as # 1.

Next, except that a second film constituting a fourth dielectric film having a thickness of 12.5 nm containing a material composed of TiO ₂ and N (refractive index = 2.7) as a main component is formed. Thus, an optical recording medium comparison sample # 1 was produced in the same manner as the optical recording medium sample # 1. Here, the second film was produced by a reactive sputtering method using a TiO ₂ target in an atmosphere of argon gas and nitrogen gas.

Further, an optical recording medium except that a second film constituting a fourth dielectric film containing TiO ₂ (refractive index = 2.5) as a main component and having a thickness of 13.5 nm is formed. An optical recording medium comparison sample # 2 was produced in the same manner as sample # 1.

Next, a second film constituting a fourth dielectric film containing a mixture of ZrO ₂ and SiO ₂ having a molar ratio of 50:50 (refractive index = 1.92) as a main component and having a thickness of 17 nm is formed. An optical recording medium comparative sample # 3 was produced in the same manner as the optical recording medium sample # 1 except for the points formed.

  The optical recording medium samples # 1 to # 4 and the optical recording medium comparison samples # 1 to # 3 thus produced were each made into an optical film thickness measuring apparatus “ETA-RT” (product of STEAG ETA-Optik) In this case, the refractive index of the second film constituting the fourth dielectric film was measured by irradiating a laser beam having a wavelength of 405 nm in order, and the second film was measured. It was the same as the refractive index of the dielectric material contained as a component.

  Next, the optical recording medium samples # 1 to # 4 and the optical recording medium comparison samples # 1 to # 3 are set in an optical recording medium evaluation apparatus “DDU1000” (trade name) manufactured by Pulstec Industrial Co., Ltd. While rotating at a linear velocity of .5 m / sec, the channel clock frequency is 132 MHz, the channel bit length is 0.12 μm / bit, the wavelength is 405 nm, and the power is between the recording power Pw and the base power Pb. In accordance with a predetermined pattern, an L1 recording film of each sample is irradiated with a laser beam modulated according to a predetermined pattern through a light transmission layer using an objective lens having a numerical aperture NA of 0.85. A recording mark having a length corresponding to 2T signal to 8T signal was formed, and a random signal was recorded on the L1 information layer.

  Here, when a random signal is recorded on the L1 information layer of each sample, the recording power Pw, the reproduction power Pr, and the base power Pb of the laser beam are respectively 10.6 mW, 0.7 mW, And 0.1 mW.

  Next, the random signal recorded in this way is reproduced in the same manner as described above with the laser beam reproduction power Pr set to 0.7 mW, and the clock jitter (%) of the reproduction signal is measured. did.

  Here, the clock jitter was calculated from σ / Tw (Tw: one cycle of the clock) by obtaining the fluctuation σ of the reproduction signal with a time interval analyzer.

  The jitter calculation results are shown in Table 1.

  Next, the support substrate and the L0 information layer are peeled from the optical recording medium samples # 1 to # 4 and the optical recording medium comparison samples # 1 to # 3, respectively, and the transparent intermediate layer, the L1 information layer, and the light transmission layer are peeled off. A laminate composed of layers is cut out, and each laminate is irradiated with a laser beam having a wavelength of 405 nm from the light transmission layer side, and the amount of transmitted light that has passed through the laminate is measured to obtain a light transmittance (%). Was calculated.

  The calculation results of the light transmittance (%) are shown in Table 1.

  As is clear from Table 1, in order to increase the light transmittance of the L1 information layer including the L1 recording film formed of the Sb eutectic phase change material, the reflection film is provided on the support substrate side. It is effective to form the fourth dielectric film formed and to form the second film set to the thickest film with a dielectric material having a refractive index of 2.0 or more, In order to improve the recording characteristics of the L1 information layer, it has been found that it is effective to form the second film with a dielectric material having a refractive index of 2.4 or less.

  Therefore, the L1 information layer is formed of an Sb eutectic phase change material, the reflection film provided on the support substrate side with respect to the L1 recording film, and the support substrate with respect to the reflection film. The second dielectric film is set to the thickest of the two or more films of the fourth dielectric film when the fourth dielectric film is provided on the side and includes the fourth dielectric film having two or more films. When the film is formed of a dielectric material having a refractive index of 2.0 to 2.4, it is possible to greatly improve the recording characteristics while maintaining the light transmittance of the L1 information layer. It has been found that the light transmittance and recording characteristics of the layer can be compatible at a high level.

  Further, as described above, the optical recording medium samples # 1 to # 4 and the optical recording medium comparison samples # 1 to # 3 are respectively produced, and the random signal is recorded on the L1 information layer. A laser beam is irradiated to each L0 recording film of each sample through the light transmission layer and the L1 information layer, a recording mark is formed on each L0 recording film, and a random signal is recorded on each L0 information layer, When the random signal recorded in each L0 information layer was reproduced in the same manner as the random signal recorded in the L1 information layer was reproduced, in the optical recording medium comparison sample # 3, as desired, A random signal was recorded on each L0 information layer, and the random signal recorded on each L0 information layer could not be reproduced, whereas the optical recording medium samples # 1 to # 4 and the optical recording medium comparison In the pull # 1 to # 2, as desired, to each L0 information layer, recording a random signal, it was possible to reproduce a random signal recorded on the L0 information layer.

Therefore, as is clear from these results, the L1 recording film formed of the Sb eutectic phase change material, the reflective film provided on the support substrate side with respect to the recording film, and the reflective film In an optical recording medium provided with an L1 information layer provided on the support substrate side and including a second film formed of a dielectric material having a refractive index of 2.0 to 2.4, the L0 information layer and It has been found that it is possible to record data in any information layer of the L1 information layer and reproduce the recorded data as desired.
Example 2
In the same manner as in Example 1, optical recording medium sample # 1 and optical recording medium comparison samples # 1 and # 2 were respectively produced, and each sample was set in the above-described optical recording medium evaluation apparatus, and laser The beam power is modulated between the recording power Pw and the base power Pb according to a predetermined pattern, and a random signal is recorded in the L1 information layer of each sample and recorded in the same manner as in the first embodiment. The random signal thus reproduced was reproduced, and the clock jitter (%) of the reproduced signal was measured.

  Here, when a random signal is recorded on the L1 information layer of each sample, the recording power Pw, the reproduction power Pr, and the base power Pb of the laser beam are respectively set to 8.8 mW, 0.7 mW, When reproducing the random signal recorded in the L1 information layer of each sample, the reproduction power Pr of the laser beam was set to 0.7 mW.

  Next, each of L1 of the optical recording medium sample # 1 and the optical recording medium comparison samples # 1 and # 2 is similarly obtained except that the recording power Pw is sequentially changed from 0.2 mW to 12.6 mW. A recording mark having a length corresponding to 2T signal to 8T signal in the 1,7RLL modulation system is formed on the recording film, a random signal is recorded on each L1 information layer, and the recorded random signal is reproduced. The clock jitter (%) of the reproduced signal was measured.

  The jitter measurement result for optical recording medium sample # 1 is shown by curve A in FIG. 5, and the jitter measurement result for optical recording medium comparison sample # 1 is shown by curve B in FIG. The jitter measurement results for are shown by curve C in FIG.

  As is apparent from FIG. 5, the L1 recording film formed of the Sb eutectic phase change material, the reflection film provided on the support substrate side with respect to the L1 recording film, and the support for the reflection film In the optical recording medium comparison samples # 1 and # 2 provided with the L1 information layer including the second film formed on the substrate side and formed of a dielectric material having a refractive index exceeding 2.4, Even at the recording power Pw, the jitter of the reproduced signal was large, whereas the L1 recording film formed of the Sb eutectic phase change material and the reflection film provided on the support substrate side with respect to the recording film Optical recording medium comprising an L1 information layer including a film and a second film provided on the support substrate side with respect to the reflective film and formed of a dielectric material having a refractive index of 2.0 to 2.4 For sample # 1, optical recording medium comparison sample # 1 Than the fine # 2, in any of the recording power Pw, the jitter of the reproduced signal is small, it is possible to significantly improve the recording characteristics was found.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the optical recording medium 10 according to the embodiment, the fourth dielectric film 31 is set to a thickness that is greater than the thickness of the first film 312 and the first film 312. Although the film 311 is stacked and configured, the fourth dielectric film is not necessarily configured by stacking the first film and the second film. The dielectric film may be formed by laminating three or more films.

  In the optical recording medium 10 according to the embodiment, the fourth dielectric film 31 includes the first film 312 and the first film 312 formed of a dielectric material having a refractive index of 2.0 to 2.4. The second film 311 is laminated and configured, but all the films constituting the fourth dielectric film are made of a dielectric material having a refractive index of 2.0 to 2.4. Is not necessarily required. Of the films constituting the fourth dielectric film, the thickest film may be formed of a dielectric material having a refractive index of 2.0 to 2.4.

  Further, in the optical recording medium 10 according to the embodiment, the L1 information layer 30 includes the fourth dielectric film 31, the reflective film 32, the third dielectric film 33, the L1 recording film 34, and the second dielectric material. The film 35, the first dielectric film 36, and the heat dissipation film 37 are laminated, and the L1 information layer includes the L1 recording film and the reflection provided on the support substrate side with respect to the L1 recording film. It is only necessary to include a film and a dielectric film provided on the support substrate side with respect to the reflective film, and other configurations are not particularly limited. For example, the second dielectric film, the first dielectric film, Any one of the dielectric film and the heat dissipation film can be omitted.

In the optical recording medium 10 according to the above embodiment, the second dielectric film 35, the third dielectric film 33, and the first film 312 of the fourth dielectric film 31 are all in molar ratio. Is formed of a 97: 3 mixture of ZrO ₂ and Y ₂ O ₃ , and the first dielectric film, the third dielectric film, and the first dielectric film are all the first dielectric film. It is not always necessary to be formed by a mixture of ZrO ₂ and Y ₂ O ₃ having a molar ratio of 97: 3.

  Furthermore, the optical recording medium 10 according to the embodiment includes the support substrate 11, the L0 information layer 20, the transparent intermediate layer 12, the L1 information layer 30, and the light transmission layer 13, and two information layers are provided. However, it is not always necessary for the optical recording medium to include two information layers, and the optical recording medium includes three or more information layers stacked via a transparent intermediate layer. May be. When the optical recording medium includes three or more information layers, all the information layers other than the information layer farthest from the light incident surface of the laser beam are all from the support substrate side, the fourth dielectric film, The reflective film and the recording film do not need to be included, and at least one information layer may include the fourth dielectric film, the reflective film, and the recording film from the support substrate side.

  In the optical recording medium 10 according to the embodiment, the L0 information layer farthest from the light incident surface of the laser beam includes the L0 recording film 23 formed of a phase change material, and is configured as a rewritable information layer. However, it is not always necessary that the L0 information layer farthest from the light incident surface of the laser beam is configured as a rewritable information layer. The L0 information layer may be a read-only information layer or a write-once information layer. May be configured. For example, when the L0 information layer is configured as a read-only information layer, the information layer as the L0 information layer is not particularly provided, and the support substrate functions as the information layer farthest from the light incident surface of the laser beam. A prepit is formed on the surface of the support substrate, and data is recorded by the prepit.

  Further, the optical recording medium 10 according to the embodiment includes the light transmission layer 13 and is configured so that the laser beam L is irradiated from the light transmission layer 13 to the L0 recording film 23 and the L1 recording film 34. However, it is not always necessary that the optical recording medium includes a light transmission layer, and the L0 recording film and the L1 recording film are irradiated with the laser beam from the light transmission layer. The support substrate made of a light transmissive material may be provided, and the laser beam may be irradiated from the support substrate to the L0 recording film and the L1 recording film.

FIG. 1 is a partially cut away schematic perspective view showing an optical recording medium according to a preferred embodiment of the present invention. FIG. 2 is a schematic enlarged cross-sectional view of a portion indicated by A in FIG. FIG. 3 is a schematic enlarged cross-sectional view of the L0 information layer 20. FIG. 4 is a schematic enlarged cross-sectional view of the L1 information layer 30. FIG. 5 is a graph showing the jitter of the optical recording medium sample # 1 and the optical recording medium comparison samples # 1 and # 2.

Explanation of symbols

10: Optical recording medium 11: Support substrate 12: Transparent intermediate layer 13: Light transmission layer 20: L0 information layer 21, 32: Reflective film 22: Second dielectric film 23: L0 recording film 24: First dielectric Film 25: Heat dissipation film 30: L1 information layer 31: Fourth dielectric film 33: Third dielectric film 34: L1 recording film 35: Second dielectric film 36: First dielectric film 37: Heat dissipation Membrane 311: Second membrane 312: First membrane

Claims (4)

A plurality of information layers laminated on at least a transparent intermediate layer on a support substrate, and at least one of information layers other than the information layer farthest from the light incident surface of the laser beam among the plurality of information layers. An information layer is formed of a Sb eutectic phase change material, a reflective film provided on the support substrate side with respect to the recording film, and the support substrate side with respect to the reflective film An optical recording medium comprising: a dielectric film provided on a substrate, wherein the dielectric film is formed of a dielectric material having a refractive index of 2.0 to 2.4. A plurality of information layers laminated on at least a transparent intermediate layer on a support substrate, and at least one of information layers other than the information layer farthest from the light incident surface of the laser beam among the plurality of information layers. An information layer is formed of a Sb eutectic phase change material, a reflective film provided on the support substrate side with respect to the recording film, and the support substrate side with respect to the reflective film A dielectric film having two or more films, and of the two or more films, the thickest film is made of a dielectric material having a refractive index of 2.0 to 2.4. An optical recording medium formed. The optical recording medium according to claim 2, wherein all of the two or more films are formed of a dielectric material having a refractive index of 2.0 to 2.4. The optical recording medium according to any one of claims 1 to 3, wherein the dielectric material has a refractive index of 2.1 to 2.4.

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