JP4194064B2 - Phase change optical information recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an information recording medium for recording or reproducing information by light such as a laser, and more particularly to a phase change optical information recording medium excellent in sensitivity suitable for increasing the recording density.
[0002]
[Prior art]
Conventionally, optical disks such as CDR-R and CD-RW record sound, text, or image signals along the circumferential direction on a plastic circular substrate such as polycarbonate or a recording layer provided thereon. The reflective layer is formed by depositing or sputtering a metal such as aluminum, gold or silver on the surface. In this case, laser light is incident from the substrate surface side of the optical disc, and signal recording and reproduction are performed.
[0003]
In recent years, the amount of information handled by computer memory, memory for image and sound files, optical cards, etc. has increased greatly, so that the signal recording capacity of optical discs and the amount of signal information are high, such as DVD-RAM and DVD-RW. Densification is progressing. Currently, the recording capacity of a CD is about 650 MB, and the capacity of a DVD is about 4.7 GB. However, a higher recording density is required.
[0004]
As a method for increasing the recording density, it has been studied to shorten the wavelength of the light source in the optical system and increase the numerical aperture NA (Numerical Aperture) of the objective lens. However, it is difficult to improve the recording density only by two-dimensional recording. I came. In view of this, a method for accumulating information records by multilayering recording layers in the thickness direction of the recording medium has been studied.
[0005]
As such a multilayering method, for example, Japanese Patent Laid-Open No. 8-287474 has been proposed. However, in this example, although the concept of multi-layering is described, since the specific contents regarding the recording medium are not described, the implementation method is unknown.
On the other hand, a multilayer recording method in which a phase change recording layer is provided in the light incident direction is introduced in JP-A-9-198709 and JP-A-11-195243. In any of these examples, the example shows a recording layer in which the layer structure is two layers, the layer through which light is first transmitted is Sb ₂ Se ₃ , and the other layers are composed of a Ge ₂ Sb ₂ Te ₅ composition. . However, in this configuration, when performing high-speed recording, there is a problem that recording sensitivity is deteriorated and high-density recording is difficult.
[0006]
For example, when the recording layer is multi-layered as in a two-layer structure, the thickness of the first layer on the light incident side is made extremely thin in order to improve the light irradiation to the second recording layer or improve the transmission of reflected light. Then, although the light transmittance increases, the film thickness becomes non-uniform or a large laser output is required in the crystallization process, that is, the initialization process. In addition, even if a heat dissipation layer is provided, if the thickness is increased, there is a problem that the light transmittance is extremely lowered or light is not transmitted. If the heat radiation characteristics are poor, heat radiation is not sufficiently performed, and there is a problem that the recording layer crystal becomes difficult to be amorphous during high-speed recording. As described above, there has been a technically difficult problem in realizing a multilayer structure (two or more layers).
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a phase change optical information recording medium capable of high-speed recording / reproducing with good light transmission and excellent recording sensitivity.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention comprises a first recording layer and a second recording layer in order from the light incident side in a constituent layer on a substrate, the first recording layer and the second recording layer. Are phase change optical information recording media sandwiched between a light incident side protective layer and a light emission side protective layer, respectively, wherein the first recording layer is composed of a composition containing at least Sb element and Te element, and The light emitting side protective layer of the first recording layer is made of any of indium oxide, indium oxide / tin oxide composite oxide, tin oxide / antimony oxide composite oxide, and vanadium oxide, has a melting point of 1100 K or more, and a light transmittance of 30. By being a metal oxide of at least%, light transmittance and recording sensitivity are improved.
[0009]
Hereinafter, the present invention will be specifically described. According to the first aspect of the present invention, the first recording layer and the second recording layer are sequentially provided from the light incident side in the constituent layers on the substrate, and each of the first recording layer and the second recording layer is light incident. In the phase change optical information recording medium sandwiched between the side protective layer and the light emission side protective layer, the first recording layer is composed of a composition containing at least Sb element and Te element, and the first recording layer The light emitting side protective layer is made of any of indium oxide, indium oxide / tin oxide composite oxide, tin oxide / antimony oxide composite oxide, and vanadium oxide, and has a melting point of 1100 K or more and a light transmittance of 30% or more. A phase change optical information recording medium characterized by being an oxide. With the above configuration, the sensitivity and light transmittance of the first recording layer are improved, thereby enabling high-speed recording / reproduction of each of the first recording layer and the second recording layer.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be further described below with reference to the drawings. 1 and 2 are schematic cross-sectional views of the layer structure of a phase change optical information recording medium according to the present invention.
[0015]
In FIG. 1 and FIG. 2, a second recording layer 7 is provided in addition to the first recording layer 3 made of a composition containing at least Sb element and Te element. The first recording layer 3 and the second recording layer 7 are sandwiched between the light incident side protection layers (2, 6) and the light emission side protection layers (4, 8), respectively. The side protective layer 4 is a metal oxide having a melting point of 1100 K or higher and a light transmittance of 30% or higher. In FIG. 1, the incident light is on the substrate 1 side, and in FIG. 2, the incident light is on the transmissive film layer 12 side.
[0016]
In FIGS. 1 and 2, glass, ceramics, or resin is usually used as the material of the substrate, but a resin substrate is preferable in terms of moldability and cost. Examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, and urethane resin. Polycarbonate resin and acrylic resin are preferable in terms of moldability, optical characteristics, and cost.
[0017]
An uneven pattern is formed on one side of the substrate surface. For example, in FIG. 1, the light incident side protective layer 2, the first recording layer 3, and the light emission side protective layer 4 (metal) are sequentially formed on the uneven pattern forming surface side of the substrate 1. Oxide protective layer), resin layer 5, light incident side protective layer 6, second recording layer 7, light emitting side protective layer 8, heat radiation layer 9, organic protective layer 10 and the like are formed. The thickness of the substrate 1 is not particularly limited. For example, in the case of the configuration of FIG. 2 in which laser light is not irradiated from the substrate 1 side, it is not necessary to consider the optical characteristics of the substrate 1, and polyethylene terephthalate having excellent rigidity is preferable.
[0018]
1 and 2, the light emitting side protective layer 4 (metal oxide protective layer) is a metal oxide having a melting point of 1100K or higher and a light transmittance of 30% or higher, for example, indium oxide, indium oxide / tin oxide composite oxide. Material (ITO), tin oxide / antimony oxide composite oxide (ATO), and vanadium oxide (VO), and in addition to increasing the recording sensitivity of the first recording layer 3 and improving the light transmission, This has the effect of preventing deterioration and deterioration of the layer and increasing the adhesive strength of the recording layer.
Further, the light incident side protective layers 2 and 6 and the light emission side protective layers 4 and 8 prevent deterioration and alteration of the first recording layer 3 and the second recording layer 7, and improve the adhesive strength of the recording layers 3 and 7, respectively. , Having a function effect such as improving recording characteristics, such as SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₃ , TiO ₂ , In ₂ O ₃ , MgO, ZrO _2, and other metal oxides, Si ₃ N ₄ , nitrides such as AlN, TiN, BN, ZrN, sulfides such as ZnS, In ₂ S ₃ , TaS ₄ , carbides such as SiC, TaC, B ₄ C, WC, TiC, ZrC, diamond-like carbon, or A mixture thereof may be mentioned. These materials can be used alone or as a mixture. When heat resistance is required, the melting point must be higher than that of the recording layer. As such a layer forming method, various vapor phase growth methods such as a vacuum deposition method, a sputtering method, a plasma CVD method, a photo CVD method, an ion plating method, an electron beam evaporation method and the like are used. Among these, the sputtering method is excellent in mass productivity and film quality.
[0019]
As the heat dissipation layer 9, a metal material such as Al, Au, Ag, Cu, Ta, or an alloy thereof can be used. Moreover, Cr, Ti, Si, Cu, Ag, Pd, Ta, etc. can be used as an additive element to these metal materials. Such a heat dissipation layer can be formed by various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, optical Cvd, ion plating, and electron beam deposition. Among these, the sputtering method is excellent in mass productivity and film quality.
[0020]
As the organic protective layer 10, an ultraviolet curable resin having a high curing speed suitable for a coating operation such as spin coating is preferable.
[0021]
When a high numerical aperture (NA) objective lens is used, the permeable membrane layer 12 is required to have a thickness of 0.3 mm or less, and thus is preferably a thin layer (sheet shape). Examples of the material include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, and urethane resin. Of these, polycarbonate resins and acrylic resins, which are excellent in terms of optical characteristics and cost, are preferable. Examples of the method for forming the permeable membrane layer include a method of adhering with an ultraviolet curable resin, or a method of attaching through a transparent double-sided pressure-sensitive adhesive sheet. Alternatively, a light transmissive layer may be formed by applying an ultraviolet curable resin on the protective layer and curing it.
[0022]
Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples.
[0023]
【Example】
Example 1
On the polycarbonate substrate having a track pitch of 0.40 μm and a thickness of 0.6 mm and having an uneven surface, the same constituent layer as that shown in FIG. 1 was formed as follows to produce an optical disk (media).
First, in a single wafer sputtering apparatus, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 2, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 15 nm as the first recording layer 3, and indium oxide is used as the light emission side protective layer 4. (In ₂ O ₃ ) was deposited to a thickness of 15 nm. Next, an ultraviolet curable resin was spin-coated as the resin layer 5, and unevenness was transferred by a stamper before curing, and then cured to form 10 μm of the resin layer 5. Next, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 6, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 12 nm as the second recording layer 7, ZnS · SiO ₂ is 12 nm as the light emitting side protective layer 8, and the heat dissipation layer 9 As a film, Ag was deposited in a thickness of 100 nm sequentially with a single-wafer sputtering apparatus, and finally an ultraviolet curable resin was applied and cured to form an organic protective layer 10 (5 μm) to form a medium.
[0024]
Comparative Example 1
A medium of Comparative Example 1 having the same layer configuration as that of FIG. 1 was prepared under the same conditions as in Example 1 except that the light emitting side protective layer 4 was omitted.
[0025]
The recording / reproduction characteristics (modulation at the optical output of the first recording layer with minimum jitter recording sensitivity (recording / reproduction signal amplitude)) of the medium of Example 1 and the medium of Comparative Example 1 were evaluated. The evaluation conditions were laser wavelength: 400 nm, numerical aperture NA of the objective lens of the optical system: 0.65, rotational linear velocity of the disk: 6.5 m / s, and recording linear density: 0.17 μm / bit. As a result of the evaluation, the recording / reproducing signal amplitude of Example 1 was 18% higher than that of Comparative Example 1, and the jitter was 2.5% lower.
[0026]
Example 2
A structural layer similar to that shown in FIG. 2 was formed on a polycarbonate substrate having a track pitch of 0.34 μm and an uneven surface with a thickness of 0.6 mm in the following manner to produce an optical disk (media).
First, in the single wafer sputtering apparatus, Ag is 100 nm as the heat radiation layer 9, ZnS · SiO ₂ is 10 nm as the light emitting side protective layer 8, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 15 nm as the second recording layer 7, light A ZnS · SiO ₂ film having a thickness of 30 nm was formed as the incident side protective layer 6. Next, an ultraviolet curable resin was spin-coated as a resin layer, the unevenness was transferred by a stamper before curing, and then cured to form a resin layer 5 of 20 μm. Next, indium oxide (In ₂ O ₃ ) is 10 nm as the light emitting side protective layer 4, Ge ₂ Sb ₂ Te ₅ is 10 nm as the first recording layer 3, and ZnS · SiO ₂ is 40 nm as the light incident side protective layer 2. Sequentially, a film was formed using a single wafer sputtering apparatus. Finally, a polycarbonate permeable membrane layer 12 (0.1 mm) was provided through a double-sided adhesive sheet-like adhesive layer 11 (0.02 mm) to form a medium.
[0027]
Comparative Example 2
A medium of Comparative Example 2 having the same layer configuration as that of FIG. 2 was prepared under the same conditions as in Example 2 except that the light emitting side protective layer 4 was omitted.
[0028]
The recording / reproduction characteristics (modulation at the optical output of the first recording layer with minimum jitter recording sensitivity (recording / reproduction signal amplitude)) of the medium of Example 2 and the medium of Comparative Example 2 were evaluated. The evaluation conditions were laser wavelength: 400 nm, numerical aperture NA of the objective lens of the optical system: 0.85, rotational linear velocity of the disc: 6.0 m / s, and recording linear density: 0.13 μm / bit. As a result of the evaluation, the recording / reproducing signal amplitude of Example 2 was 30% higher than that of Comparative Example 2, and the jitter could be recorded 5% lower.
[0029]
Example 3
A constituent layer similar to that shown in FIG. 1 was formed on a polycarbonate substrate having a track pitch of 0.41 μm and a thickness of 0.6 mm and provided with irregularities on the surface in the following manner to produce an optical disc (media).
First, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 2, 12 nm of In ₄ Sb ₇₂ Te ₂₄ is used as the first recording layer 3, and indium oxide / oxide is used as the light emitting side protective layer 4 in a single wafer sputtering apparatus. Tin composite oxide (ITO) was deposited to 5 nm. Next, an ultraviolet curable resin was spin-coated as a resin layer, the unevenness was transferred by a stamper before curing, and then cured to form a resin layer 5 of 15 μm. Next, ZnS · SiO ₂ is 30 nm as the light incident side protective layer 6, In ₄ Sb ₇₂ Te ₂₄ is 12 nm as the second recording layer 7, ZnS · SiO ₂ is 12 nm as the light emitting side protective layer 8, and Ag is used as the heat dissipation layer 9. Were sequentially formed into a film by a single-wafer sputtering apparatus, and finally an ultraviolet curable resin was applied and cured to form an organic protective layer 10 (5 μm) to form a medium.
[0030]
Comparative Example 3
1 is formed as follows on a polycarbonate substrate having a track pitch of 0.41 μm and an uneven surface with a thickness of 0.6 mm, and an optical disc (media) of a comparative example is formed. Created.
First, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 2, In ₄ Sb ₇₂ Te ₂₄ is 15 nm as the first recording layer 3, and indium oxide / oxide is used as the light emitting side protective layer 4 in a single wafer sputtering apparatus. Tin composite oxide (ITO) was deposited to 5 nm. Next, an ultraviolet curable resin was spin-coated as a resin layer, the unevenness was transferred by a stamper before curing, and then cured to form a resin layer 5 of 15 μm. Next, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 6, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 12 nm as the second recording layer 7, ZnS · SiO ₂ is 12 nm as the light emitting side protective layer 8, and the heat dissipation layer 9 As a film, Ag was deposited in a thickness of 100 nm sequentially with a single-wafer sputtering apparatus, and finally an ultraviolet curable resin was applied and cured to form an organic protective layer 10 (5 μm) to form a medium.
[0031]
The recording / reproducing characteristics (modulation at the optical output of the first recording layer with the minimum jitter recording sensitivity (recording / reproducing signal amplitude)) of the medium of Example 3 and the medium of Comparative Example 3 were evaluated. The evaluation conditions were laser wavelength: 400 nm, numerical aperture NA of the objective lens of the optical system: 0.65, rotational linear velocity of the disk: 6.5 m / s, and recording linear density: 0.17 μm / bit. As a result of the evaluation, the recording / reproducing signal amplitude of Example 1 was 23% higher than that of Comparative Example 1, and the jitter was also 6% lower.
[0032]
Example 4
A structural layer similar to that shown in FIG. 2 was formed on a polycarbonate substrate having a track pitch of 0.36 μm and an uneven surface with a thickness of 0.6 mm in the following manner to produce an optical disc (media).
First, in a single wafer sputtering device, Ag is 100 nm as the heat dissipation layer 9, ZnS · SiO ₂ is 10 nm as the light emitting side protective layer 8, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 15 nm as the second recording layer 7, light A ZnS · SiO ₂ film having a thickness of 20 nm was formed as the incident-side protective layer 6. Next, an ultraviolet curable resin was spin-coated as a resin layer, and unevenness was transferred by a stamper before curing, and then cured to form a resin layer 5 of 22 μm. Next, tin oxide / antimony oxide composite oxide (ATO) is 8 nm as the light emitting side protective layer 4, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 10 nm as the first recording layer 3, and ZnS • is used as the light incident side protective layer 2. SiO ₂ was sequentially deposited at 40 nm using a single wafer sputtering apparatus. Finally, a polycarbonate permeable membrane layer 12 (0.08 mm) was provided through a double-sided adhesive sheet-like adhesive layer 11 (0.02 mm) to form a medium.
[0033]
Comparative Example 4
The light emitting side protective layer 4 is omitted, the light incident side protective layer 6 (ZnS · SiO ₂ ) is 10 nm, and the resin layer 5 is 10 μm. The media of Comparative Example 4 was created.
[0034]
The recording / reproduction characteristics (modulation at the optical output of the first recording layer with minimum jitter recording sensitivity (recording / reproduction signal amplitude)) of the medium of Example 4 and the medium of Comparative Example 4 were evaluated. The evaluation conditions were laser wavelength: 400 nm, numerical aperture NA of the objective lens of the optical system: 0.85, rotational linear velocity of the disc: 6.0 m / s, and recording linear density: 0.13 μm / bit. As a result of the evaluation, the recording / reproducing signal amplitude of Example 4 was 35% higher than that of Comparative Example 4, and the jitter was also 5% lower.
[0035]
Example 5
A constituent layer similar to that shown in FIG. 1 was formed on a polycarbonate substrate having a track pitch of 0.44 μm and an uneven surface with a thickness of 0.6 mm as follows to produce an optical disc (media).
First, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 2, Ge ₂ Sb ₂ Te ₅ is 15 nm as the first recording layer 3, and vanadium oxide (VO) is used as the light emitting side protective layer 4 in the single wafer sputtering apparatus. ) Was deposited to 5 nm. Next, an ultraviolet curable resin was spin-coated as a resin layer, the unevenness was transferred by a stamper before curing, and then cured to form a resin layer 5 of 15 μm. Next, ZnS · SiO ₂ is 30 nm as the light incident side protective layer 6, Ag ₂ In ₂ Sb ₇₂ Te ₂₄ is 12 nm as the second recording layer 7, ZnS · SiO ₂ is 12 nm as the light emitting side protective layer 8, and the heat dissipation layer 9 As a film, Ag was deposited in a thickness of 100 nm sequentially with a single-wafer sputtering apparatus, and finally an ultraviolet curable resin was applied and cured to form an organic protective layer 10 (5 μm) to form a medium.
[0036]
Comparative Example 5
1 is formed as follows on a polycarbonate substrate having a track pitch of 0.44 μm and an uneven surface with a thickness of 0.6 mm, and an optical disc (media) of a comparative example is formed. Created.
First, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 2, In ₄ Sb ₇₂ Te ₂₄ is 15 nm as the first recording layer 3, and indium oxide / oxide is used as the light emitting side protective layer 4 in a single wafer sputtering apparatus. Tin composite oxide (ITO) was deposited to 5 nm. Next, an ultraviolet curable resin was spin-coated as a resin layer, the unevenness was transferred by a stamper before curing, and then cured to form a resin layer 5 of 15 μm. Next, ZnS · SiO ₂ is 40 nm as the light incident side protective layer 6, Ag ₂ In ₃ Sb ₇₀ Te ₂₅ is 12 nm as the second recording layer 7, ZnS · SiO ₂ is 12 nm as the light emitting side protective layer 8, and the heat dissipation layer 9 As a film, Ag was deposited in a thickness of 100 nm sequentially with a single-wafer sputtering apparatus, and finally an ultraviolet curable resin was applied and cured to form an organic protective layer 10 (5 μm) to form a medium.
[0037]
The recording / reproduction characteristics (modulation at the optical output of the first recording layer with minimum jitter recording sensitivity (recording / reproduction signal amplitude)) of the medium of Example 5 and the medium of Comparative Example 5 were evaluated. The evaluation conditions were laser wavelength: 400 nm, numerical aperture NA of the objective lens of the optical system: 0.65, rotational linear velocity of the disk: 6.5 m / s, and recording linear density: 0.17 μm / bit. As a result of the evaluation, the recording / reproducing signal amplitude of Example 5 was 22% higher than that of Comparative Example 5, and the jitter was also 2% lower.
[0038]
【The invention's effect】
The structure of the present invention of claim 1 , that is, the first recording layer on the light incident side is composed of a composition containing at least Sb element and Te element, and the light emitting side protective layer of the first recording layer is indium oxide, It is made of any one of indium oxide / tin oxide composite oxide, tin oxide / antimony oxide composite oxide, and vanadium oxide, and is a metal oxide having a melting point of 1100 K or more and a light transmittance of 30% or more, thereby providing light transmittance. Since the recording sensitivity can be improved and the recording sensitivity can be improved, a phase change optical information recording medium capable of high-speed recording / reproducing is provided.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a layer configuration of a phase change optical information recording medium in which light is incident on a substrate side.
FIG. 2 is a schematic cross-sectional view of a layer structure of a phase change optical information recording medium in which light is incident on a transmission film layer side.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Light incident side protective layer 3 First recording layer 4 Light emission side protective layer 5 Resin layer 6 Light incident side protective layer 7 Second recording layer 8 Light emission side protective layer 9 Heat radiation layer 10 Organic protective layer 11 Adhesive layer 12 Permeation membrane layer

Claims (1)

A constituent layer on the substrate includes a first recording layer and a second recording layer sequentially from the light incident side, and the first recording layer and the second recording layer are respectively a light incident side protective layer and a light emitting side. In the phase change optical information recording medium sandwiched between the protective layers, the first recording layer is composed of a composition containing at least Sb element and Te element, and the light emitting side protective layer of the first recording layer includes , Indium oxide, indium oxide / tin oxide composite oxide, tin oxide / antimony oxide composite oxide, and vanadium oxide, having a melting point of 1100 K or more and a light transmittance of 30% or more. A phase change optical information recording medium.

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