JP2001209970A - Information recording medium, method of producing the same and method of recording and reproducing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical information recording medium with high reliability in which information signals can be recorded and reproduced with high density and at a fast line velocity by making the initialization unnecessary. SOLUTION: The information recording medium 50 has a recording layer 5 on a substrate 1, and the recording layer 5 consists of a phase transition layer 4 which causes reversible phase transition between a crystal state and an amorphous state by irradiation of a light beam 27 and a crystallization improving layer 3 which improves the ability of crystallization of the phase transition layer. The crystallization improving layer 3 is formed before the phase transition layer 4 is formed, and while the phase transition layer 4 is formed, crystallization nuclei are produced and the crystal is grown so that at least a part of the phase transition layer 4 is formed into the crystal phase after the film is formed. The obtained information recording medium makes recording in an as-deposited medium possible without requiring an initialization process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information recording medium capable of optically recording, reproducing, erasing, and rewriting information, a method of manufacturing the same, and a method of recording and reproducing the same.

[0002]

2. Description of the Related Art Conventionally, a phase change type information recording medium causes a reversible phase transformation between a crystalline state and an amorphous state by a method such as sputtering on a transparent disk substrate in a film forming process. A multilayer film including a recording layer is formed. The structure of the recording layer after film formation is amorphous, and the entire recording layer is changed from an amorphous state to a crystalline phase using optical or thermal means.
Through the following (initialization step), a phase change type information recording medium is manufactured. (In the present specification, the thus formed amorphous film is referred to as as-depo amorphous, and the high power described below is used.
It is distinguished from amorphous formed by rapid cooling after melting by laser irradiation. The phase change type information recording medium modulates a single laser beam into high power and low power and irradiates the recording layer,
Recording and rewriting of signals are possible. When a high-power laser beam is irradiated, the recording layer is melted and quenched, an amorphous (recorded state) is formed, and a low-power laser beam is irradiated,
When the recording layer is heated and cooled slowly, a crystalline phase (erased state) is formed, and a recording mark having a level of 0.1 μm (several 100 nm) is formed on the track. The signal reproduction is performed by a difference ΔR (%) between the reflectance Rc (%) of the medium when the recording layer is in a crystalline phase and the reflectance Ra (%) of the medium when the recording layer is in an amorphous state. (△ R = | Rc-Ra |). Recording and reproduction of signals can be performed on any medium of Rc> Ra or Ra> Rc.

In the above-described initialization step, the reflectance of the medium changes from Ra to Rc. In particular, a medium optically designed to satisfy Ra> Rc has a low reflectance, so that Rc is desirably 10% or more.

[0004] The initialization step requires equipment provided with optical or thermal means. For example, when a semiconductor laser is used as an optical means, various operations such as the shape of a laser beam, a laser irradiation power, a cooling speed, a rotation speed of a medium, and a required time are also optimized for various media. It costs. It is also known that the volume shrinkage of the recording layer is reduced by several percent when the recording layer undergoes a phase transformation from an amorphous phase to a crystalline phase. Therefore, when the recording layer is crystallized after the formation of the multilayer film, a new internal stress that is not present after the film formation is generated at least in a layer in contact with the recording layer due to volume shrinkage of the recording layer. Also, 10
A very thin recording layer of nm or less has low light absorption and easily diffuses heat.Thus, crystallization requires a higher power density, and a thermal load is applied to grooves and address pits previously transferred on the substrate. For example, the initialization process has many problems.

If the initialization step can be made unnecessary,
Capital and development costs can be reduced, leading to significant media cost reductions. There are different methods that can eliminate the need for initialization for (1) a medium with Rc> Ra and (2) a medium with Ra> Rc. In order to obtain good servo characteristics, it is preferable that the reflectivity be maintained at a higher value.In the case of (1), the recording layer is in a crystalline phase after film formation (initial state Rc), and in (2) If
The recording layer is amorphous after film formation (initial state R
a) is the condition. (The initial state refers to the state of the medium before recording.) In order to implement these, a technique for crystallizing the recording layer during film formation and a technique for recording as-depo amorphous are required.

A method for crystallizing a recording layer of a phase change type optical information recording medium during film formation is disclosed in International Publication No. WO98 / 47142. After providing a crystallization promoting layer made of a material whose crystal structure is a face-centered cubic lattice system or a rhombohedral lattice system, a manufacturing method of forming a recording layer immediately above the crystallization promoting layer, and during the formation of the recording layer This is a production method in which the substrate temperature is changed from 45 ° C. to 110 ° C. Further, as a material of the crystallization promoting layer, S
b, Bi, Sb compound, including at least one of the Bi compound, it is disclosed that the recording layer of the phase change optical information recording medium manufactured by this manufacturing method is formed in a crystalline state. .

Further, as a method for manufacturing a phase-change optical information recording medium configured to satisfy Ra> Rc, a method for manufacturing a recording layer in which a substrate temperature during film formation is 35 ° C. to 150 ° C. and A production method in which the substrate temperature immediately before film formation is 35 ° C. or more and 95 ° C. or less is disclosed in International Publication No. WO98 / 38636. The phase-change optical information recording medium manufactured by this manufacturing method, even when recording is performed without performing the initialization process on the as-depo amorphous recording layer, high recording characteristics are obtained from the first recording. It is disclosed.

However, with respect to WO98 / 47142,
Bi has a low melting point of about 271 ° C. and does not have high sputtering power. Further, with respect to WO98 / 38636, in order to heat the substrate and form the recording layer into an as-depo amorphous film, the entire surface of the substrate must be uniformly heated and maintained at that temperature. No. For example, when heating the substrate holder itself, it is very difficult to uniformly increase the temperature unless the entire surface of the substrate holder contacts the substrate in order to conduct heat to the substrate. However, there is a problem that when the substrate is brought into full contact with the holder, the surface of the substrate is liable to be scratched or stained. In addition, when performing high-frequency induction or flash heating, etc., in order to uniformly heat the substrate in a non-contact manner in a vacuum device, the film forming equipment becomes complicated, and in addition, the film is formed immediately before or during film formation. There is a problem that it is difficult to stably maintain a constant temperature. Further, there is a need to measure the temperature of the substrate in a vacuum device in a non-contact manner, and to monitor the temperature outside the device, and it is inevitable that the device becomes complicated and large.

Conventionally, it has been difficult to perform recording on an as-depo amorphous material because an as-depo amorphous material is different from an amorphous material formed by irradiating a crystal phase with a laser. This is probably due to the nature. In general, amorphous has several metastable energy states, and when a medium is stored for a long period of time or under high temperature conditions, the medium may change to an energy state different from that before storage. Therefore, since the optimum recording and reproducing conditions are different before and after storage, if the recording and reproducing are performed under the same conditions, the recording and reproducing characteristics may change. For example, when the recording mark of the recording layer has shifted to a more stable energy state, the erasing sensitivity for crystallizing the recording layer is reduced, so that the erasing rate when the information signal is overwritten may be reduced. is there.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and uses a material having a high melting point. The recording layer becomes a crystalline phase after film formation without heating the substrate, thereby eliminating the need for an initialization step. A first object is to provide an information recording medium and a method for manufacturing the same, and to provide an information recording medium that reduces energy required for crystallization.

Further, the present invention solves the above-mentioned problems, and strict control of the temperature of the substrate is not required immediately before and during film formation, and an information recording medium optically designed to satisfy Ra> Rc is provided.
A second object of the present invention is to provide an information recording medium capable of performing a recording operation in a state where a recording layer is in an as-depo amorphous state without performing an initialization step.

Further, the present invention solves the above-mentioned problem, and does not require an initialization step. Even if Rc is almost 0%, an information recording medium capable of stably reading an address and performing tracking servo control. A third object is to provide a manufacturing method thereof and a recording / reproducing method thereof.

[0013]

In order to achieve the above object, the present invention provides an information recording medium having at least a recording layer formed on a substrate, wherein the recording layer is brought into a crystalline state by irradiation with a light beam. Including a phase transformation layer that causes a reversible phase transformation between the amorphous state and a crystallization ability improving layer that improves the crystallization ability of the phase transformation layer, before forming the phase transformation layer. By forming the crystallization ability improving layer in the above, the phase transformation layer causes crystal nucleation and crystal growth during the film formation,
At least a part of the phase transformation layer is in a crystalline phase after film formation. At this time, it is preferable that the crystallinity improving layer is selected from telluride or halide.
Specifically, telluride is SnTe, PbTe, Te, Sb ₂ Te ₃ , Bi ₂ T
e ₃ , GeSbTe, GeBiTe eutectic, with a film thickness of 1 nm to 1
0 nm is desirable. Halides are ZnF ₂ , AlF ₃ , KF, CaF ₂ , Na
Selected from F, BaF ₂ , MgF ₂ , LaF ₃ , and LiF, and the film thickness is from 1 nm to 2
0 nm is desirable. In addition, the phase transformation layer is preferably made of a material having GeSbTe as a main component and having a crystal structure of a rock salt type, and more preferably the crystal structure of the crystallization capability improving layer is a rock salt type. The deposition rate for forming the phase transformation layer is from 5 nm / min to 20
It is preferable to form a film in the range of nm / min. By using a material that is a telluride or a halide for the crystallization capability improving layer and forming the phase change layer at a low film formation rate, the phase change layer can be made into a crystalline phase after film formation.

Further, according to the present invention, the energy for crystallizing the recording layer in the case where the crystallization ability improving layer is formed is A,
When the energy for crystallizing the recording layer in the case where the crystallization ability improving layer is not formed is represented by B, A also has the effect of making A smaller than B.

According to another aspect of the present invention, there is provided a first information recording medium having at least a first recording layer formed on a first substrate, and at least a second information recording medium formed on a second substrate. A two-layer information recording medium, wherein the first recording layer has a crystalline state and an amorphous state by irradiation of a light beam. A phase transformation layer that causes a reversible phase transformation between, and a layer that is a crystallization ability improving layer that improves the crystallization ability of the phase transformation layer,
By forming the crystallization ability improving layer before forming the phase transformation layer, the phase transformation layer causes crystal nucleation and crystal growth during film formation, and at least a part of the phase transformation layer. Has a crystalline phase after film formation. With this configuration, the first recording layer has a function of generating crystal nuclei and crystal growth during film formation, and at least a part of the first recording layer has a crystal phase after film formation.

The present invention also relates to an information recording medium comprising at least a recording layer on a substrate, wherein the recording layer undergoes a reversible phase transformation between a crystalline state and an amorphous state by irradiation with a light beam. The phase transformation layer which occurs (here, the layer is not limited to the case where it is formed uniformly on one surface, but also includes the case where it is formed in an island shape. The same applies to the crystal nucleus supply layer). And a crystal nucleus supply layer laminated on the transformation layer to facilitate crystallization of the phase transformation layer. According to the information recording medium, recording can be started while the phase change layer is in an as-depo amorphous state. According to the information recording medium, an information recording medium with high reliability in recording and reproducing information signals with high density and high linear velocity can be obtained.

In the information recording medium, it is preferable that the crystal nucleus supply layer and the phase transformation layer are stacked in this order from the substrate side. The information recording medium further includes a second crystal nucleus supply layer that facilitates crystallization of the phase transformation layer, wherein the phase transformation layer and the second crystal nucleus supply layer are arranged in this order from the substrate side. It is preferable that they are stacked. In the information recording medium, it is preferable that the phase change layer and the crystal nucleus supply layer are stacked in this order from the substrate side.

In the information recording medium, a transition temperature (hereinafter referred to as a crystallization temperature) Tx1 (° C.) of the crystal nucleus supply layer from an amorphous state to a crystal phase, and a crystallization temperature Tx2 (° C.) of the phase change layer. )
Preferably satisfy the relationship of Tx2> Tx1. With the above configuration, crystallization of the phase transformation layer is facilitated. In the information recording medium, the melting point Tm1 (° C.) of the crystal nucleus supply layer;
It is preferable that the melting point Tm2 (° C.) of the phase transformation layer satisfies the relationship of Tm1> Tm2. According to the above configuration, even when the crystal nucleus supply layer is disposed on the laser beam incident side with respect to the phase transformation layer, an information recording medium with high stability of the crystal nucleus supply layer can be obtained.

In the above information recording medium, the crystal nucleus supply layer preferably contains Te. With the above configuration, Te functions as a crystal nucleus, so that crystallization of the phase transformation layer is facilitated. In the information recording medium, the crystal nucleus supply layer may be formed of SnTe
And at least one selected from PbTe. In the information recording medium, the crystal nucleus supply layer may include:
SnTe-M (where M is N, Ag, Cu, Co, Ge, Mn, Nb, Ni, Pd, Pt, Sb,
(Including at least one selected from Se, Ti, V, Zr and PbTe). Here, SnTe-M is obtained by adding M to SnTe without changing the ratio of Te to Sn. For example, it includes a compound of SnTe and M, a eutectic of SnTe and M, and the like. The content of M is preferably at most 50%. A more preferred M content is in the range of 0.5-50 atom%. Further, SnTe is more preferably a stoichiometric composition of Sn ₅₀ Te ₅₀ (Sn: Te = 50: 50), but Sn ₄₅ Te ₅₅ (Sn: Te = 45: 55), Sn ₅₅ Te ₄₅
A tolerance of about ± 5% such as (Sn: Te = 55: 45) is possible.

In the above information recording medium, the phase transformation layer is
It is preferably made of a chalcogen-based material. With the above configuration, an information recording medium capable of high-density recording can be obtained.
In the information recording medium, the phase transformation layer is formed of GeTe, GeSbTe,
It is preferable to include at least one selected from TeSnSe, InSbTe, GeBiTe, and AgInSbTe. In the above information recording medium, the phase transformation layer is composed of GeSbTe and Ag, Sn, Cr, Mn, Pb, Bi, P
It preferably contains at least one element selected from d, Se, In, Ti, Zr, Au, Pt, Al and N.

In the above information recording medium, the thickness d1 (nm) of the crystal nucleus supply layer and the thickness d2 (nm) of the phase transformation layer satisfy d2>
It is preferable to satisfy the relationship of d1. With the above configuration,
Insufficient light quantity of the laser beam incident on the phase transformation layer can be prevented. In the information recording medium, it is preferable that the thickness d1 (nm) of the crystal nucleus supply layer satisfies a relationship of 0.3 <d1 ≦ 5. In the information recording medium, the thickness d2 of the phase transformation layer
(nm) preferably satisfies the relationship of 3 ≦ d2 ≦ 20.

In the above information recording medium, the reflectance Rc (%) of the information recording medium when the phase change layer is a crystalline phase and the reflectance of the information recording medium when the phase change layer is amorphous Ra
(%) Preferably satisfies the relationship of Ra> Rc. With the above configuration, it is possible to obtain an information recording medium in which it is particularly easy to detect a groove or an address formed in a substrate.

The method for manufacturing an information recording medium according to the present invention is a method for manufacturing an information recording medium having at least a recording layer, wherein a phase that causes a reversible phase transformation between a crystalline state and an amorphous state is provided. Forming a recording layer including a transformation layer and a crystal nucleus supply layer laminated on the phase transformation layer to facilitate crystallization of the phase transformation layer. According to the method for manufacturing an information recording medium, the information recording medium of the present invention can be easily manufactured. In the above-mentioned manufacturing method, it is preferable that the step of forming the phase transformation layer is performed under the condition that the phase transformation layer becomes amorphous. With the above configuration, as-depo recording becomes possible.

In the above-mentioned manufacturing method, it is preferable that the film formation rate r (nm / min) of the phase transformation layer satisfies the relationship of r ≧ 30.
With the above structure, the phase transformation layer can be formed in an amorphous state.

Further, the method for recording / reproducing information on an information recording medium according to the present invention is a method for recording information on an information recording medium provided with a recording layer, wherein the recording layer is switched between a crystalline state and an amorphous state. A phase transformation layer that causes phase transformation reversibly, and a crystal nucleus supply layer that is stacked on the phase transformation layer and facilitates crystallization of the phase transformation layer, by irradiating the recording layer with a laser beam, The information is recorded by performing phase transformation on the phase transformation layer. According to the information recording medium recording / reproducing method, information can be recorded with high reliability.

In the above recording / reproducing method, it is preferable that the crystal nucleus supply layer contains at least one selected from SnTe and PbTe. According to the above configuration, information can be recorded particularly reliably.

In the above recording / reproducing method, the phase transformation layer is
It is preferable to include at least one selected from GeTe, GeSbTe, TeSnSe, InSbTe, GeBiTe, and AgInSbTe. According to the above configuration, information can be recorded particularly reliably.

[0028] In the above recording / reproducing method, the phase transformation layer comprises:
It is preferable that the film be formed in an amorphous state and the recording of the information be started in an amorphous state without crystallization.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, FIGS. 1 to 3 explain an invention in which a phase transformation layer is crystallized after film formation for the purpose of eliminating the need for initialization.

FIG. 1 shows an example of the configuration of an information recording medium 50 according to the present invention, in which a protective layer 2, a crystallization enhancing layer 3, a phase transformation layer 4, a protective layer 6, and a reflective layer 7 are sequentially formed on a substrate 1. They are laminated and bonded to a dummy substrate 9 with an adhesive layer 8. The recording layer 5
It consists of two layers, a crystallization ability improving layer 3 and a phase transformation layer 4.

As the substrate 1, a transparent disk-shaped material such as a polycarbonate resin, a polymethyl methacrylate resin, a polyolefin resin, a norbornene resin, an ultraviolet curable resin, and glass can be used. The thickness of the substrate 1 is not particularly limited, but a thickness of about 0.05 to 2.0 mm can be used. A spiral or concentric guide groove for tracking laser light is provided on the surface of the substrate 1 on which the film is formed, as needed. The surface on which the film is not formed should be smooth.

The protective layers 2 and 6 are dielectric thin films, and have a function of adjusting the optical distance to increase the light absorption efficiency to the recording layer and increasing the change in the amount of reflected light before and after recording to increase the signal amplitude. The recording layer 5 is physically and chemically stable for the purpose of suppressing an increase in noise due to thermal damage to the recording layer 5 and adjusting the reflectance, absorptance, and the phase of the reflected light with respect to the laser beam 27. It is preferable to use a material that has a melting point and a softening temperature higher than the melting point and does not form a solid solution with the material of the recording layer. For example, Y,
Oxides such as Ce, Ti, Zr, Nb, Ta, Co, Zn, Al, Si, Ge, Sn, Pb, Sb, Bi, Te, Ti, Zr, Nb, Ta, Cr, Mo, W, B, Nitrides such as Al, Ga, In, Si, Ge, Sn, Pb, carbides such as Ti, Zr, Nb, Ta, Cr, Mo, W, Si, Zn, Cd
For example, a dielectric material such as a sulfide, a selenide or telluride, a fluoride such as Mg or Ca, a simple substance such as C, Si, or Ge, or a mixture thereof may be used. Among these, ZnS—SiO _2, which is a mixture, is an amorphous material, has a high refractive index, has a high film forming rate, and has excellent mechanical properties and moisture resistance, and is a particularly excellent protective layer. The thickness of the protective layer is calculated by, for example, a matrix method (for example, see Hiroshi Kubota, `` Wave Optics '', Iwanami Shinsho, 1971, Chapter 3). Status
It can be strictly determined so as to satisfy the condition that the change in the reflected light amount (after recording) is larger and the light absorption rate to the recording layer 5 is larger. The protective layers 2 and 6 may be made of different materials and compositions as needed, or may be made of the same material and composition.

The crystallization-capability improving layer 3 of the present invention causes crystal nucleation and crystal growth of the phase transformation layer 4 formed on the crystallization capability improving layer 3, and forms the phase transformation layer 4 during the film formation. It has the function of crystallization. If the crystallization ability improving layer 3 itself has a crystal structure after the film formation, the function thereof is further enhanced. Generally, the structure of a thin film obtained by cooling a gas phase is easily affected by the structure of a substrate. It is considered that providing a crystalline material layer before forming the phase transformation layer 4 promotes crystallization. It is considered that the effect is greater when the recording layer has the same crystal structure. For example, in the case of the Ge—Sb—Te system, since the crystallinity improving layer 3 is a rock salt type crystal because the crystallinity enhancing layer 3 is also a rock salt type, its function becomes larger. As the material of the crystallization ability improving layer 3, SnTe fast crystallization materials, PbTe, Te of low melting point _{material, Sb 2 Te 3, Bi 2} Te 3, GeSbTe eutectic, Te products such as GeBiTe eutectic or CaF, _{2, MgF 2, LaF, AlF} 3, NaF, BaF 2, KF, Li
Halides such as F and ZnF ₂ have a crystallization effect. In particular, SnTe, PbTe, NaF, LiF, and KF had a large effect. In order to increase the light absorption to the phase transformation layer 4, in the case of a Te compound, the crystallinity enhancement layer 3 itself has light absorption, so that the thickness is 1 nm to 10 nm.
Very thin film thickness is preferable, and in the case of a halide, the crystallinity improving layer 3 itself has almost no light absorption, so that the thickness is 1 nm to 20 nm.
It is possible to set the film thickness within the range.

The phase transformation layer 4 undergoes a reversible phase transformation between a crystalline phase and an amorphous state by irradiation with a light beam, and has an optical constant (refractive index n, extinction coefficient k). It is preferred to use a changing material. Ge-Sb-Te, G mainly composed of Te
e-Bi-Te systems or these systems with Au, Ag, Cu, Al, P
A material to which any one of d, Pt, Ce, Sn, Mn, Cr, and Ti is added can also be used. Further, nitrogen can be added. Particularly Ge-Sb-Te can GeTe-Sb ₂ Te ₃ pseudo-binary system composition to ensure good recording and erasing performance as high speed crystallizing material. A composition range of GeTe: Sb ₂ Te ₃ = x: 1 (1 ≦ x ≦ 6) is excellent in phase stability and is a practically preferable composition. Using the material containing Te as a main component as a base material, the phase transformation layer 4 containing nitrogen was formed by a reactive sputtering method in an atmosphere of Ar gas and N2 gas. Evaluation of the phase structure after the formation of the crystallization ability improving layer 3 and the phase transformation layer 4 was performed by forming a thin film of about 10 nm on quartz glass and heating the temperature to about 350 ° C. with a He-Ne laser. The temperature at which the optical change occurred was investigated. Further, the complex refractive index for a predetermined laser wavelength was calculated by experimentally examining the film thickness, the reflectance, and the transmittance of the crystallizing ability improving layer 3. Using the obtained complex refractive index, an optical calculation of the multilayer film was performed by a matrix method, and the configuration of the information recording medium was determined.

The recording layer 5 of the present invention has a two-layer structure in which a crystallinity improving layer 3 is formed and then a phase change layer 4 is formed. By having a two-layer structure, crystal nuclei are easily generated at the interface of the phase transformation layer 4 with the crystallization ability improving layer 3 side,
The phase transformation layer 4 causes crystal growth and becomes crystalline after film formation. Recording and reproduction of information are performed by an optical change of the phase transformation layer 4. Hereinafter, unless otherwise specified, the case where the phase transformation layer 4 is in a crystalline state or an amorphous state is referred to as a recording layer, respectively.
5 is expressed as a crystalline state or an amorphous state.

The reflection layer 7 has a function of optically increasing the amount of light absorbed by the recording layer 5 and thermally diffusing the heat generated in the recording layer 5 quickly to facilitate amorphization. ,
Further, it also has a role of protecting the multilayer film from the use environment. As a material of the reflective layer 7, for example, Al, Au, A
g, a single metal material having a high thermal conductivity such as Cu, or one or more of these elements as a main component, and one or more of them as appropriate for improving moisture resistance or adjusting thermal conductivity. Al-Cr, Al-Ti, Ag-Pd, Ag-
Alloy materials such as Pd-Cu and Ag-Pd-Ti can be used.
All of these materials are excellent in corrosion resistance and satisfy quenching conditions. Note that the reflective layer 7 may easily be made sufficiently amorphous without a quenching effect depending on the recording conditions such as the linear velocity or the composition of the phase transformation layer, and may be omitted.

After forming the protective layer 2 to the reflective layer 7, the adhesive layer 8 was spin-coated on the reflective layer 7 and bonded to the dummy substrate 9.

As the adhesive layer 8, a material having high heat resistance and high adhesiveness, for example, an adhesive resin such as an ultraviolet curable resin can be used, and a material mainly composed of an acrylic resin or a material mainly composed of an epoxy resin can be used. Materials can be used. The same material, or an adhesive resin such as a UV curable resin of a different material, a double-sided tape, a dielectric film, or a combination of these as appropriate, is used as a single-sided disk by bonding to another dummy substrate as shown in FIG. Or
It is also possible to form a double-sided disc by laminating the same film surfaces face to face.

The dummy substrate 9 is for increasing the mechanical strength of the information recording medium 50 and protecting the laminated multilayer film. The material of the dummy substrate 9 can be selected from the material of the substrate 1. It is important that the information recording medium 50 having the bonded structure does not cause mechanical warpage or distortion, and the dummy substrate 9 and the substrate 1 do not necessarily need to be made of the same material, and need not have the same thickness. Absent.

FIG. 2 shows an example of the configuration of an information recording medium 51 according to the present invention, in which a protective layer 2, an interface layer 10, and a crystallization ability improving layer are provided on a substrate 1.
3, a phase transformation layer 4, an interface layer 11, a protective layer 6, a light absorption correction layer 12, and a reflective layer 7 are sequentially laminated, and an adhesive layer 8 is attached to a dummy substrate 9. This configuration is such that the light absorption coefficient Ac of the recording layer 5 when the recording layer 5 is in the crystalline state is larger than the light absorption coefficient Aa when the recording layer 5 is in the amorphous state, so that the reflective layer In this configuration, a light absorption correction layer 12 is provided between the layers 7 to balance light absorption. Also in this configuration, the crystallization of the phase transformation layer 4 could be verified by forming the crystallization capability improving layer 3 in advance of the phase transformation layer 4.

The substrate 1, the protective layers 2, 6, the crystallinity improving layer 3, the phase transformation layer 4, the reflective layer 7, the adhesive layer 8, and the dummy substrate 9 can be made of the same material as in FIG.

The interface layers 10 and 11 have a function of preventing mass transfer between the protective layer 2 and the recording layer 5 and between the protective layer 6 and the recording layer 5 due to repeated recording, and include Si, Al, Zr, Ti, and Ge. , Ta, Cr, etc. as main components, nitrides, oxides, nitrided oxides, carbides,
Alternatively, a material mainly containing a mixture thereof is preferable. In addition, the above function is exhibited only by providing one of the interface layers 10 or 11, but it is more preferable to provide both, and in that case, different materials and compositions may be used as needed, or the same material may be used. Materials and compositions can also be used. These interface layer materials can be formed by reactive sputtering of a metal base material in an Ar gas and reaction gas atmosphere, or by sputtering a compound base material in an Ar gas atmosphere. If the thickness of the interface layer is large, the reflectivity and the absorptivity of the multilayer structure greatly change and affect the recording / erasing performance. Therefore, the thickness is preferably 2 nm to 10 nm, and more preferably about 2 nm to 5 nm.

The light absorption correction layer 12 adjusts the light absorption ratio between the case where the recording layer 5 is in the crystalline state and the case where the recording layer 5 is in the amorphous state, so that the mark shape is not distorted during overwriting. A material having a high refractive index and appropriately absorbing light for the purpose of increasing the reflectance difference between the case where the recording layer 5 is in the crystalline state and the case where the recording layer 5 is in the amorphous state and increasing the signal amplitude. Is preferred. For example, the refractive index n is 3 or more and 6 or less,
A material having an extinction coefficient k of 1 or more and 4 or less can be used. Specifically, amorphous Ge alloys and Si alloys such as Ge-Cr, Ge-Mo, Si-Cr, Si-Mo, and Si-W, Te compounds, or T
It is preferable to use crystalline metals, semimetals and semiconductor materials such as i, Zr, Nb, Ta, Cr, Mo, W, SnTe, PbTe.

FIG. 3 shows an example of the structure of a two-layer information recording medium 52 according to the present invention.
It is a structure where 29 are stuck together. Since the laser beam 27 is incident from the first substrate side 13 and the information recording media 20 and 29 are recorded / reproduced from one side, there is no need to turn the media over and the recording / reproducing capacity is approximately doubled.

The first substrate 13 and the second substrate 28 can use the same material as the substrate 1 of FIG.

The first protective layers 14 and 19 and the second protective layers 22 and 26
Can be made of the same material as the protective layers 2 and 6 in FIG.

The first interface layers 15, 18 and the second interface layers 23, 25
Can be made of the same material as the interface layers 10 and 11 in FIG.

The crystallization-enhancing layer 3 of the present invention is formed on the first optical information recording medium 20, and uses the same material as in FIG.

The second information recording medium 29 is a first information recording medium.
Since recording and reproduction are performed by the laser beam 27 incident through the optical disk 20, the first information recording medium 20 is optically designed so that the transmittance is as high as possible. Therefore, the phase transformation layer 4 of the information medium 20 is set to an extremely thin film thickness of about 5 nm to about 8 nm. The crystallization ability improving layer 3 also preferably has a small thickness of 1 nm to 3 nm. Since the phase transformation layer 4 is thin, a larger laser energy is required in the initialization step. However, forming the crystallization ability improving layer 3 even at 1 nm makes it easier to crystallize the phase transformation layer 4 and increase the laser energy. Was significantly reduced. By forming a further 3 nm, the phase transformation layer 4 was crystallized after the film formation.

For the second recording layer 24, the same material as that of the phase transformation layer 4 is used.

The first recording layer 17 of the present invention corresponds to the recording layer 5 shown in FIG.
Has the same function as.

The separation layer 21 is transparent and heat-resistant at the wavelength λ of the laser light 27 in order to perform recording and reproduction with the laser light 27 on each of the first information recording medium 20 and the second information recording medium 29. It is preferable that the material has high adhesiveness. Specifically, for example, an adhesive resin such as an ultraviolet curable resin,
A double-sided tape, a dielectric film, or a combination thereof can be used as appropriate. In addition, the thickness of the separation layer 21 disturbs signal information recorded on one of the first information recording medium 20 and the second information recording medium 29 when performing recording / reproduction on the other. Or, in order to avoid that it leaks, it is necessary to be more than the depth of focus, for example, 2μm or more, and the first information recording medium
In order to be able to focus the laser beam 27 on both the 20 and the second information recording medium 29, the total with the substrate thickness is within the range of the substrate thickness tolerance,
For example, it needs to be 100 μm or less.

The reflective layer 7 is made of the same material as that shown in FIG.

FIGS. 5 to 7 illustrate the invention in which the recording is performed in an as-depo amorphous state without the need for initialization.

FIG. 5 shows an example of the configuration of an information recording medium 53 according to the present invention, in which a protective layer 2, an interface layer 10, a crystal nucleus supply layer
32, a phase transformation layer 33, an interface layer 11, a protective layer 6, and a reflective layer 7 are sequentially laminated and bonded to a dummy substrate 9 with an adhesive layer 8. The recording layer 31 includes a crystal nucleus supply layer 32 and a phase transformation layer 33 that are sequentially stacked from the substrate 1 side. (The same applies to the following embodiments).

The recording layer 31 includes a crystal nucleus supply layer 32 and a phase transformation layer 33 stacked on the substrate 1. Crystal nucleus supply layer 32
Is a layer for facilitating crystallization of the phase transformation layer 33.
The phase transformation layer 33 is a layer that reversibly undergoes phase transformation between a crystalline state and an amorphous state, and is a layer that records information by this phase transformation. In the information recording medium 53, the recording layer 31
Has the above structure, the phase transformation layer 33 is a crystal nucleus supply layer
Crystallization is likely to occur from the interface with 32.

In order to facilitate crystallization of the phase transformation layer 33, the crystallization nucleus supply layer 32 has a higher crystallization temperature (transition temperature from an amorphous phase to a crystal phase) than the phase transformation layer 33. It is preferable to use a material that is low and has a stable crystalline state. That is, the crystallization temperature Tx1 (° C.) of the crystal nucleus supply layer 32 and the phase transformation layer 33
And the crystallization temperature Tx2 (° C.) preferably satisfy the relationship of Tx2> Tx1 (the same applies to the following embodiments).

The phase transformation layer 33 is made of a material that undergoes a reversible phase transformation between a crystalline state and an amorphous state by light beam irradiation. The phase transformation layer 33 is made of, for example, a chalcogen-based material. Specifically, the phase transformation layer 33 preferably contains at least one selected from the group consisting of chalcogen-based materials, such as GeTe, GeSbTe, TeSnSe, InSbTe, GeBiTe, and AgInSbTe. In addition, GeSbTe and Ag, Sn, Cr, P
A material containing at least one element selected from b, Bi, Pd, Se, In, Ti, Zr, Au, Pt, Al, Mn, Cu and N may be used. In particular, in the case of a Ge—Sb—Te-based material, a GeTe—Sb ₂ Te ₃ pseudo-binary composition is preferable because good recording / erasing performance can be secured as a high-speed crystallization material. In this case, GeTe: S
A composition range of b ₂ Te ₃ = 1 to 6: 1 is a practically preferable composition because of excellent phase stability. The crystallization temperature of the phase transformation layer 33 is from about 140 ° C. to about 240 ° C., and the melting point is from about 600 ° C. to about 650 ° C.
It is. The crystal structure of the phase transformation layer 33 is of NaCl type in the case of crystallization by laser irradiation. Also, the phase transformation layer 33
Is in an amorphous state at the time of formation, and as-depo recording is possible. The thickness of the phase transformation layer 33 is, for example, not less than 3 nm and not more than 20 nm.

Therefore, as the material of the crystal nucleus supply layer 32, a material containing Te is preferable, and a material containing at least one selected from SnTe and PbTe is particularly preferable.

When the crystal nucleus supply layer 32 is formed on the laser incident side of the phase transformation layer 33 as in the information recording medium 53, the light beam reaches and is absorbed by the crystal nucleus supply layer 32 first. The melting point of the crystal nucleus supply layer 32 is preferably higher than the melting point of the phase transformation layer 33. That is, the melting point Tm1 (° C.) of the crystal nucleus supply layer 32
And the melting point Tm2 (° C.) of the phase transformation layer 33 preferably satisfy the relationship of Tm1> Tm2. This is because, when recording a signal by irradiating the high-power laser beam to the phase transformation layer 33, in the process of melting and quenching, the crystal nucleus supply layer 32 is also melted at the same time and the function as the crystal nucleus supply layer is impaired. This is to prevent that. Here, Table 1 shows that as a material of the crystal nucleus supply layer 32, T
Shows the crystallization temperature and melting point of the material containing e.

[0061]

[Table 1]

As shown in Table 1, from the viewpoint of the melting point, it is understood that SnTe and PbTe are particularly preferable as the material of the crystal nucleus supply layer.

Since the crystal nucleus supply layer 32 is preferably stable in a crystalline state, the thickness of the crystal nucleus supply layer 32 is preferably 2 nm or more, and more preferably thicker.
(Because the number of atoms required for crystallization is insufficient when thin.) However, when the crystal nucleus supply layer 32 is thick,
The energy beam is absorbed by 32 and the phase transformation layer 33
Energy beam does not reach the Therefore, the thickness of the crystal nucleus supply layer 32 is preferably 2 nm or more and 4 nm or less.

The crystal nucleus supply layer 32 can be formed by sputtering a base material in an Ar gas or Ar-N ₂ mixed gas atmosphere. Further, the phase transformation layer 33 is made of Ar gas or Ar-N
_It can be formed by sputtering a base material in a mixed gas atmosphere. At this time, after the phase transformation layer 33 is formed,
In order to be -depo amorphous, the deposition rate of the phase transformation layer 33 is preferably about 30 nm / min or more. According to experiments performed by the present inventors, when the thickness of the crystallization-capability improving layer is 5 nm and the thickness of the recording layer is 10 nm, the recording layer is being formed at a deposition rate of 5 nm / min to 20 nm / min. At 30 nm / min to 40 nm / min, the as-depo amorphous and crystalline phase were mixed, and at 50 nm / min or more, the mixture became as-depo amorphous. Even when the crystal nucleus supply layer 32 is present as in the reversible optical information recording medium 10, the phase transformation layer
If the deposition rate of 33 is low, the phase transformation layer 33 may be crystallized during the deposition. Depending on the combination of the film thickness of the crystal nucleus supply layer 32 and the film thickness of the phase transformation layer 33, the film formation rate at which the phase transformation layer 33 crystallizes during film formation differs, but the crystallization of the phase transformation layer 33 is prevented. For this purpose, the deposition rate of the phase transformation layer 33 is preferably 30 nm / min or more, and more preferably 40 nm / min or more.

In the information recording medium 53, SnTe, SnTe-M (where M is N, Ag, Cu, Co, Ge, Mn, Nb, N
i, including Pd, Pt, Sb, Se, Ti, V, at least one selected from Zr and _{PbTe), PbTe, Sb 2 Te} 3, Bi 2 Te 3, Te, GeSbTe eutectic, G
Regardless of which eBiTe eutectic is used, the phase transformation layer 33 has an as-de
It was possible to record information in the amorphous state of po (as-depo recording). In particular, good results were obtained when a material containing SnTe having a high melting point or a material containing PbTe was used.

As the phase transformation layer 33, GeTe, GeSbTe, Te
SnSe, InSbTe, GeBiTe, including at least one selected from AgInSbTe and GeSbTe, and Ag, Sn, Cr, Pb, Bi, Pd, Se, I
As-depo recording was possible using any of the materials to which at least one selected from n, Ti, Zr, Au, Pt, Al, Mn and N was added.

As described above, according to the information recording medium 53,
As-depo recording becomes possible.

FIG. 6 is a sectional view showing an example of the configuration of the information recording medium 54 of the present invention. Referring to FIG. 6, the information recording medium 54 includes a substrate 1, a protective layer 2 sequentially laminated on the substrate 1,
Interface layer 10, recording layer 34, interface layer 11, protective layer 6, and reflective layer 7
And a dummy substrate adhered on the reflective layer 7 by the adhesive layer 8
9 is provided. The recording layer 34 includes a phase transformation layer 33 and a crystal nucleus supply layer 35 that are sequentially stacked from the substrate 1 side. In addition,
The portions other than the recording layer 34 are the same as those of the information recording medium 53 described with reference to FIG. 5, and thus the description thereof will not be repeated.

Recording layer 34, crystal nucleus supply layer 35, and phase transformation layer
The functions of 33 are the same as those of the recording layer 31, the crystal nucleus supply layer 32, and the phase transformation layer 33 described with reference to FIG. That is,
The crystal nucleus supply layer 35 is a layer for facilitating crystallization of the phase transformation layer 33. The phase transformation layer 33 is a layer that reversibly undergoes phase transformation between a crystalline state and an amorphous state, and is a layer that records information by this phase transformation. Information recording medium 54
Since the recording layer 34 has the above configuration, the phase transformation layer 33
Is easily crystallized from the interface with the crystal nucleus supply layer.

In the information recording medium 54, unlike the case of FIG. 5, the recording layer 34 is composed of the phase transformation layer 3 sequentially laminated from the substrate 1 side.
3 and a crystal nucleus supply layer 35.

The phase transformation layer 33 is a phase transformation layer of the information recording medium 53.
Same as 33.

Unlike the crystal nucleus supply layer 32 of the information recording medium 53, the crystal nucleus supply layer 35 is stacked on the phase transformation layer 33 on the side opposite to the laser incident side. Therefore, a material having a melting point lower than the melting point of the phase transformation layer 33 can be suitably used for the crystal nucleus supply layer 35. Specifically, in addition to the material of the crystal nucleus supply layer 32 described with reference to FIG.
e, PbTe, Sb ₂ Te ₃ , Bi ₂ Te ₃ , Te, GeSbTe eutectic composition, Ge
A BiTe eutectic composition can also be suitably used. Also, information recording media
In 54, since the energy beam enters the crystal nucleus supply layer 35 after passing through the phase transformation layer 33, the thickness of the crystal nucleus supply layer 35 can be thicker than that of the information recording medium 53. In particular,
The thickness of the crystal nucleus supply layer 35 is preferably about 2 nm to 5 nm. Further, the film forming rate of the phase transformation layer 33 is preferably about 30 nm / min or more, and the film is formed in an amorphous state.

In the information recording medium 54, SnTe, SnTe-M (where M is N, Ag, Cu, Co, Ge, Mn, Nb, Ni,
Pd, Pt, Sb, Se, at least _{one), PbTe, Sb 2 Te 3} , Bi 2 Te 3, Te, GeSbTe eutectic Ti, V, selected from Zr and PbTe or GeBi,
In any case of using the Te eutectic, the phase transformation layer 33 has an as-depo
It was possible to record information in an amorphous state.
In the information recording medium 54, good results were obtained using any of the materials.

As the phase transformation layer 33, GeTe, GeSbTe, Te
SnSe, InSbTe, GeBiTe, AgInSbTe, or at least one selected from Ag, Sn, Cr, Pb, Bi, Pd, Se, In, Ti, Zr, Au, Pt, Al, Mn and N containing GeSbTe As-depo recording was possible with any of the added materials.

As described above, according to the information recording medium 54 of FIG. 6, the same effect as the information recording medium 53 can be obtained.

FIG. 7 shows an information recording medium of the present invention.
An example will be described. The information recording medium 55 includes a substrate 1, a protective layer 2, an interface layer 10, a recording layer 36, an interface layer 11, an protective layer 6 and a reflective layer 7, which are sequentially laminated on the substrate 1, and an adhesive layer on the reflective layer 7. And a dummy substrate 9 adhered with the same. The recording layer 36 is composed of the crystal nucleus supply layer 32
And a phase transformation layer 33 and a crystal nucleus supply layer 35. The recording layer
Except for 36, the information recording medium 5 described in FIG.
Since it is the same as 3, the duplicate description is omitted.

The crystal nucleus supply layers 32 and 35 have the same function as the crystal nucleus supply layer 32 described with reference to FIG. That is, the crystal nucleus supply layers 32 and 35 are layers for facilitating crystallization of the phase transformation layer 33. In the information recording medium 55, since the recording layer 36 has the above configuration, the phase transformation layer 33 includes the crystal nucleus supply layer 32.
Alternatively, crystallization is likely to occur from the interface with 35.

In the information recording medium 55, the information recording medium 5 shown in FIG.
Different from 3, the phase transformation layer 33 is sandwiched between the crystal nucleus supply layer 32 and the crystal nucleus supply layer 35.

The phase transformation layer 33 uses the same material as that described with reference to FIG.

The crystal nucleus supply layer 32 can be made of the same material as the crystal nucleus supply layer 32 described with reference to FIG. The crystal nucleus supply layer 32 has a melting point of the phase transformation layer 33 among materials containing Te.
Preferably, it is made of a higher material.

For the crystal nucleus supply layer 35, the same material as the crystal nucleus supply layer 35 described with reference to FIG. 6 can be used. Among the materials containing Te, the melting point of the crystal nucleus supply layer 35 is the phase transformation layer.
Materials having a melting point lower than 33 can also be suitably used.

The material of the crystal nucleus supply layer 32 and the material of the crystal nucleus supply layer 35 may be different. For example, the crystal nucleus supply layer 32 may be made of SnTe and the crystal nucleus supply layer 35 may be made of PbTe. Further, the crystal nucleus supply layer 32 may be made of PbTe, and the crystal nucleus supply layer 35 may be made of GeBiTe eutectic composition.
It is to be noted that using the same material for the crystal nucleus supply layer 32 and the crystal nucleus supply layer 35 has advantages in that the number of base materials can be reduced at the time of film formation and the film formation apparatus can be further simplified.

The thickness of the crystal nucleus supply layer 32 and the thickness of the crystal nucleus supply layer 35 may be different, but the total of both film thicknesses is 5 nm.
The following is preferred. For example, the crystal nucleus supply layer 32
May be 1 nm and the thickness of the crystal nucleus supply layer 35 may be 2 nm, or the thickness of the crystal nucleus supply layer 32 may be 2 nm and the thickness of the crystal nucleus supply layer 35 may be 3 nm.

In the information recording medium 55, the crystal nucleus supply layer 32
And 35 as SnTe, SnTe-M (where M is N, Ag, Cu, Co,
Ge, Mn, Nb, Ni, Pd, Pt, Sb, at least one) of Se, Ti, V, selected from Zr and _{PbTe, PbTe, Sb 2 Te 3} , Bi 2 Te 3, Te, GeSbTe eutectic, or, When using either GeBiTe eutectic, as-dep
o It was possible to record. In particular, the crystal nucleus supply layer 32
Good results were obtained when a material containing SnTe or a material containing PbTe having a high melting point was used.

As the phase transformation layer 33, GeTe, GeSbTe, TeSn
Including Se, InSbTe, GeBiTe, AgInSbTe, or GeSbTe; and
Ag, Sn, Cr, Pb, Bi, Pd, Se, In, Ti, Zr, Au, Pt, Al, Mn and N It was possible to record.

As described above, according to the information recording medium 55 of FIG. 7, the same effects as those of the information recording medium 53 can be obtained.

The information recording medium described with reference to FIGS.
The signal can be recorded without performing the initialization process while the phase transformation layer 33 is designed to be Rc and the phase transformation layer 33 is in an as-depo amorphous state.

Next, an example of a method for manufacturing an information recording medium of the present invention will be described.

The method for producing an information recording medium according to the present invention is a method for producing an information recording medium having a recording layer, wherein the phase transformation layer causes a reversible phase transformation between a crystalline state and an amorphous state. And a step of forming a recording layer including a crystal nucleus supply layer that is stacked on the phase transformation layer and facilitates crystallization of the phase transformation layer. Hereinafter, a method of manufacturing the information recording medium 53 described with reference to FIG. 5 will be described with reference to FIG.

First, the protective layer 2 and the interface layer 10 are formed on the substrate 1.
To form These layers are formed by reactive sputtering of a target (metal base material) in Ar gas and reaction gas atmosphere, or sputtering of a compound base material in Ar gas atmosphere or Ar gas and reaction gas atmosphere. Can be formed.

Next, a crystal nucleus supply layer 32 and a phase transformation layer 33 are laminated on the interface layer 10. Crystal nucleus supply layer 32 and phase transformation layer 33
Can be formed by sputtering the base material in an Ar gas or Ar-N ₂ mixed gas atmosphere. Note that the phase transformation layer 33 is formed under conditions that make it amorphous. In order for the phase transformation layer 33 to be as-depo amorphous after film formation, as described with reference to FIG. 5, the film formation rate of the phase transformation layer 33 is preferably about 30 nm / min or more.

Next, on the phase transformation layer 33, the interface layer 11 and the protective layer
6 and laminated. These layers are the protective layer 2 and the interface layer 10
It can be formed by the same method as described above.

Next, a reflective layer 7 is formed on the protective layer 6. The reflection layer 7 can be formed by a sputtering method or an evaporation method.

Finally, the adhesive layer 8 was applied on the reflective layer 7 by spin coating, and after bonding the dummy substrate 9, the adhesive layer 8 was cured by irradiating ultraviolet rays. Thus, the information recording medium 53 can be manufactured.

The information recording medium 54 or 55 can be easily manufactured by the same method as described above.

According to the above manufacturing method, the information recording medium of the present invention can be easily manufactured.

Next, an example of the recording / reproducing method of the information recording medium of the present invention will be described.

This recording / reproducing method is a recording / reproducing method using the information recording medium of the present invention described in any of FIGS.

Specifically, by irradiating a modulated laser beam to the information recording medium described in any of FIGS. 5 to 7, an amorphous region and a crystalline phase region are formed in the phase transformation layer, Record. By irradiating the laser beam to the amorphous region of the phase transformation layer with low power, the amorphous region of the irradiated portion can be crystallized. Further, by irradiating the crystal phase region of the phase transformation layer with high power with a laser beam, the crystal phase region in the irradiated portion can be made amorphous.

According to the recording / reproducing method, information signals can be recorded with high reliability. In particular, as-depo recording becomes possible by using the information recording medium shown in FIGS.

[0101]

Next, specific examples of the present invention will be described.

Examples 1 to 13 are examples of the invention in which the phase change layer is crystallized after film formation for the purpose of eliminating the need for initialization.

Embodiments 14 to 26 are embodiments of the invention in which the phase change layer is recorded in an as-depo amorphous state for the purpose of eliminating the need for initialization. Embodiment 26 is an embodiment relating to reliability.

(Example 1) In order to function as a crystallization-enhancing layer, in which the phase transformation layer is crystallized during film formation, it is considered necessary that the crystallization-enhancement layer itself be a crystal after film formation. Can be Several high-speed crystallization materials or low-melting-point materials whose crystals are more structurally stable were selected, and the phase structures of these thin films after film formation were examined. The material is Bi ₂ Te ₃ , Sb ₂ Te ₃ , Sb, Te, SnTe, PbT
e, GeSbTe eutectic and GeBiTe eutectic. Diameter: 100m
m, thickness: 6mm (hereinafter, displayed as 100mmφ × 6mmt)
Were subjected to DC sputtering in an Ar atmosphere to form thin films of 5 nm each on a quartz substrate. The transmittance of the eight types of thin films obtained was measured while heating at a rate of 50 ° C. per minute using a He-Ne laser. The relationship between the temperature and the transmittance is shown in FIGS. If the structure after film formation is amorphous, the transmittance at room temperature is relatively high as shown in FIG. A rate reduction is observed. This temperature is defined as the crystallization temperature. When the structure after film formation is in a mixed state of an amorphous phase and a crystalline phase, the transmittance at room temperature is lower than that in the case of FIG. A change is observed. In addition, the crystallization temperature is lower than in the case of FIG.
It is easier to crystallize than the state of 4A. In the lines a, b, and c in FIG. 4B, the proportions of the crystalline state and the amorphous state are different, and the proportion of the crystalline phase included in the order of a, b, and c increases.
If the structure after film formation is a crystalline phase, the transmittance at room temperature is relatively the lowest, and there is almost no change in transmittance even when the temperature is increased as shown in FIG. It is possible to determine the phase structure from such a difference. Table 2 shows the structures of the eight types of thin films at room temperature.

[0105]

[Table 2]

Example 2 It was examined whether the thin film of Example 1 had a function as a crystallization ability improving layer. In a vacuum chamber, a crystallizing ability improving layer was formed on a quartz substrate, and a phase transformation layer was continuously formed thereon, and the phase structure of the sample after film formation was examined. The film thickness is: quartz | crystallizing ability improving layer (5 nm) | phase transformation layer (10 nm). The sputtering conditions for the crystallization ability improving layer were the same as in Example 1.
Similarly, the material of the phase transformation layer is Ge ₂ Sb ₂ Te ₅ . The phase structure of the phase transformation layer was examined by transmittance measurement in the same manner as in Example 1.

[0107]

[Table 3]

When there was no crystallization capability improving layer, the Ge ₂ Sb ₂ Te ₅ phase transformation layer was amorphous after the film formation and showed a change in transmittance as shown in FIG. 4A. The crystallization temperature was about 200 ° C. S for crystallization ability enhancement layer
When b was used, the crystallization temperature of the phase transformation layer did not decrease, and crystallization and nucleation were not observed. When Bi ₂ Te ₃ , Sb ₂ Te ₃ , Te, and GeSbTe eutectic were used for the crystallization capability improving layer, the phase transformation layer became a mixed state of an amorphous and a crystalline phase. When SnTe, PbTe, GeBiTe eutectic was used for the crystallization capability improving layer, the result was as shown in FIG. 4C, and crystallization of the phase transformation layer was recognized. From these results, it was found that the use of the Te compound as the crystallization capability improving layer promoted the crystallization of the phase change layer. It was also found that among the Te compounds, the material having a rock salt type crystal structure had a greater crystallization effect.

Example 3 The relationship between the film thickness and the crystallization effect was examined using SnTe for the crystallization capability improving layer. SnTe on quartz substrate
The film is formed by changing the thickness from 1 nm to 20 nm, and the phase transformation layer is
m was formed. Table 4 shows the structures of the phase transformation layers of these samples.

[0110]

[Table 4]

At 1 nm, a mixed state of amorphous and crystalline was obtained. However, an effect that crystallization was easier than in the case where there was no crystallization ability improving layer was recognized. If it is 3 nm or more, the phase transformation layer is crystallized.

Example 4 The film forming conditions and the crystallization effect of the phase change layer were examined. A 5 nm layer of SnTe was formed on a quartz substrate, and a phase transformation layer was formed thereon with a thickness of 10 nm while changing the film formation rate. Table 5 shows the structures of the phase transformation layers of these samples.

[0113]

[Table 5]

It has been found that the effect of the crystallization-capability improving layer for crystallization of the phase change layer depends on the film formation rate of the phase change layer. The phase transformation layer was crystallized at a deposition rate of 5 nm / min to 20 nm / min, and became a mixed state of an amorphous phase and a crystalline phase at a rate of 30 nm / min to 40 nm / min. At higher speeds it was amorphous. The lower the film formation rate of the phase transformation layer, the more easily the phase transformation layer is crystallized.
The most preferred deposition rate was from 5 nm / min to 10 nm / min.

(Example 5) The complex refractive index of SnTe was experimentally determined to be n = 4.2 and extinction coefficient k = 4.5.
From the complex refractive index, the configuration of the optical information recording medium was determined by optical calculation and prototyped. The reflectance of the optical information recording medium was measured to determine whether the phase transformation layer was crystallized.

As shown in FIG. 1, a protective layer was 100 nm, a crystallization-enhancing layer was 5 nm, and a phase transformation layer was 18 nm on a polycarbonate substrate.
nm, the protective layer was 25 nm, and the reflective layer was 80 nm in this order by using a batch-type sputtering apparatus to continuously form a film in a vacuum chamber.
Table 6 shows the detailed film forming conditions.

[0117]

[Table 6]

The reflectivity of the optical information recording medium was measured by a phase change optical disk evaluation device manufactured by Pulstec. The light source has a wavelength of 660 nm and NA of 0.6. Optical information recording medium with linear velocity of 8m / s
And the reflectance of the mirror surface portion at a radius of 40 mm was measured. As a result, a reflectance of 20% was obtained.

In order to check whether or not the crystal was completely crystallized, the same position was irradiated with a semiconductor laser beam having a power sufficient for normal crystallization, and then the reflectance was measured. In this case 20.3
% Reflectance was obtained. It was verified that the phase transformation layer was almost completely crystallized after the film formation. A similar effect was observed for PbTe and GeBiTe eutectics.

(Example 6) When only the thickness of the crystallinity improving layer was changed in the multilayer structure of Example 5, it was measured how the reflectance and the recording sensitivity of the optical information recording medium changed. SnTe was used as the crystallization ability improving layer. The reflectance measurement conditions were the same as in Example 5, and the recording sensitivity was defined as the recording power at which a 3T signal was recorded once between the grooves by the same apparatus and a CNR value of 50 dB was obtained.
Table 7 shows the results.

[0121]

[Table 7]

Although the reflectivity of the multilayer film increases as the thickness of the crystallization-capability improving layer increases, the recording sensitivity decreases, and a film thickness of 15 nm or more requires a recording power of 14 mW or more, which is practically difficult. . From this result, the thickness of the crystallization-capability improving layer was 1
It was found that 10 nm was preferable.

(Example 7) The overwrite jitter characteristics of the optical information recording medium experimentally produced in Example 5 were evaluated. For comparison, the overwrite jitter characteristics of an optical information recording medium having undergone a crystallization step using a semiconductor laser in a conventional configuration having no crystallization capability improving layer were also evaluated. 3T signal between grooves once to 20
The recording was performed up to the number of times and the change in the jitter value was examined. Table 8 shows the results.

[0124]

[Table 8]

In the table, the jitter value is an average value of the jitter value between the front end and the rear end of the recording mark.

The difference between the front end jitter and the rear end jitter was within 0.5% regardless of the number of recordings.

If the crystallization of the phase transformation layer is insufficient and the amorphous phase remains in the crystal phase, the jitter value increases during the second to fourth recordings. In this example, even when recording was performed on the optical information recording medium in which the crystallization ability improving layer was provided and the phase change layer was crystallized during film formation, an increase in the jitter value was observed around the second to fourth times. I couldn't. A crystal phase almost equivalent to that of a recording film crystallized by irradiating a semiconductor laser beam after the conventional film formation was obtained.

Example 8 With the structure of the first information recording medium of the two-layer information recording medium shown in FIG. 3, the effect of the crystallinity improving layer was examined.
On the polycarbonate substrate, a protective layer of 100 nm, an interface layer of 5 nm,
The crystallinity improving layer was 3 nm, the phase transformation layer was 7 nm, the interface layer was 5 nm, and the protective layer was 90 nm. In this order, the films were continuously formed in a vacuum chamber using a batch type sputtering apparatus. Seven types of information recording media with different crystallization ability improving layer materials and an information recording medium without crystallization ability improving layer were prototyped. At the same time, a sample piece having a multilayer film formed in the same configuration on a quartz substrate was also prepared. With this sample piece, the phase structure of the phase transformation layer after film formation was examined. Bi ₂ Te ₃ , Sb ₂ Te ₃ ,
When Te, GeSbTe eutectic was used, it was a mixture of amorphous and crystalline phases. Since these are not completely amorphous, crystallization by irradiating a semiconductor laser beam on an optical information recording medium was attempted in order to evaluate the easiness of crystallization. When there was no crystallization capability improving layer, the power of the semiconductor laser required for initialization was 800 mW. This was almost the upper limit of the laser output. Table 9 shows the results when the crystallinity improving layer was used.

[0129]

[Table 9]

Even if the phase transformation layer does not become a complete crystal phase,
Initializing power by providing a crystallization ability improvement layer even at 3 nm
Was almost halved, and crystallization was found to be easier. The same effect was obtained with the crystallization ability improving layer of 1 nm.

Example 9 Example 5 was also carried out for a structure having a light absorbing layer as shown in FIG.

A protective layer of ZnS-S was formed on a polycarbonate substrate.
iO ₂ of 120 nm, GeN of the interface layer of 5 nm, and SnTe of the crystallization enhancement layer
5 nm, the phase change layer 10nm to GeSbTe of, 5 nm to GeN interface layer, 50 nm of ZnS-SiO ₂ protective layer, and 30nm of Si alloy of a light absorption correction layer, an Ag alloy reflective layer was 80nm deposited, information A recording medium was prototyped. After the film formation, the phase change layer was crystallized due to the effect of the crystallization ability improving layer, and a reflectance of 17.0% was obtained. After irradiating the same position with a semiconductor laser beam, the reflectance was measured to be 16.9%.
It was verified that the film was completely crystallized after film formation. The effect of the crystallization ability improving layer was also recognized in the configuration of FIG.

Example 10 Up to Example 9, a Te compound was used as the crystallization-improving layer, and excellent effects were obtained. However, the thickness range is limited to an extremely thin range of 5 nm or less because the crystallinity improving layer absorbs light. Therefore, it was examined whether a halide having a small light absorption and also containing a compound having a rock salt structure has a function as a crystallization ability improving layer. Material is Zn
It is nine kinds of fluorides of F ₂ , AlF ₃ , KF, CaF ₂ , NaF, BaF ₂ , MgF ₂ , LaF ₃ , and LiF. A compound sputtering target of 100 mmφ × 6 mmt was RF-sputtered in an Ar atmosphere to form a 10 nm thin film on a quartz substrate. Subsequently, the phase structure of the phase-transformed layer after film formation of a sample in which the phase-transformed layer was continuously formed to a thickness of 10 nm thereon was examined. As in Example 1, the transmittance was measured with a He-Ne laser while heating at a rate of 50 ° C. per minute. Fig. 4 (a)
-As a result of judging the phase structures of the nine samples from FIG. 4 (c), all of the samples were in a mixed state of an amorphous phase and a crystalline phase. As shown in FIG. 4 (b), the change in transmittance is shown. The materials LiF, NaF, and KF having the rock salt structure are close to the line of b, and the other materials are close to the line of a. Using a material having a rock salt type structure for the crystallization-capability improving layer increased the ratio of the crystal phase of the phase transformation layer, and was more effective as the crystallization-capability improving layer.

Example 11 Example 8 was carried out by forming a 10 nm thick halide as a crystallizing ability improving layer. Table 1 shows the results.
0 is shown.

[0135]

[Table 10]

Even when the phase change layer was in a mixed state of the amorphous phase and the crystalline phase, the initialization laser power was significantly reduced as compared with the case where the crystallization ability improving layer was not provided. It can be seen that the energy required for crystallization is reduced by providing the layer for improving the crystallization ability of the halide. Also in the case where the layer for improving the crystallization ability of the halide was provided, the effect that the phase transformation layer was easily crystallized was obtained.

(Example 12) The complex refractive index of LiF, NaF, and KF, which had a high function as a crystallization ability improving layer, was determined. Each crystallinity improving layer was formed on a quartz substrate, the film thickness was measured with a step meter, and the complex refractive index was calculated by measuring the reflectance and transmittance with a spectroscope. Table 11 shows the obtained complex refractive indices.

[0138]

[Table 11]

These films were transparent films with k = 0.

(Example 13) When the thickness of the crystallinity improving layer alone was changed in the multilayer structure of Example 8, it was measured how the reflectance and the recording sensitivity of the optical information recording medium changed. LiF was used as the crystallization capability improving layer. Table 12 shows the results.

[0141]

[Table 12]

The reflectivity of the multilayer film increases as the thickness of the crystallinity improving layer increases. At 1 nm, the reflectance was below 15%. Further, the recording sensitivity exceeding 25 nm becomes 14 mW or more. From these results, the thickness of the halide crystallinity improving layer is preferably 5 nm or more and 20 nm or less. Comparing with the result of Example 6,
It can be seen that the smaller the k of the crystallization ability improving layer itself, the more the thickness of the crystallization ability improving layer can be set.

In the above embodiments, the effects of the crystallization-enhancing layer were described with the structures shown in FIGS. 1, 2, and 3. However, the present invention is not limited to these structures, and it is necessary to form the phase change layer before forming the film. If the crystallization ability improving layer is formed, the effect can be obtained regardless of the thickness of the protective layer, the presence or absence of the interface layer, and the like.

As described above, according to the present invention, by forming a crystallization-enhancing layer at the interface of the phase transformation layer on the substrate side, the phase structure after the film formation of the phase transformation layer becomes a crystalline phase, The result is that a crystallization step requiring means is not required or crystallization can be performed with less power.

Example 14 Example 14 shows the results of a study on the material of the crystal nucleus supply layer.

In order to start recording information in the as-depo state without initializing the phase transformation layer, the as-depo amorphous portion must be recorded while being crystallized.
o It is necessary that crystal nuclei are easily generated in the amorphous phase transformation layer. The more the crystal nuclei are generated, the lower the transition temperature (crystallization temperature) from the amorphous phase to the crystalline phase.

As a material of the crystal nucleus supply layer, the crystal phase is NaCl
Several types of materials having a mold structure, a high-speed crystallization material, and a low-melting-point material were selected, and the crystallization temperature of the phase transformation layer when a phase transformation layer was laminated on these materials was examined.

The material of the crystal nucleus supply layer is Bi ₂ Te ₃ , Sb ₂ Te ₃ , S
b, Te, SnTe, PbTe, SnTe-PbTe, SnTe-Ag, SnTe-Se, SnTeN, GeS
bTe eutectic, GeBiTe eutectic, TiN, ZrN. The material of the phase transformation layer is GeSbTe.

The sample used had a layer structure of quartz substrate / crystal nucleus supply layer (film thickness 2 nm) / phase transformation layer (film thickness 10 nm). S
The crystal nucleus supply layer other than nTeN, TiN and ZrN has a diameter of 100 mm ×
A sputtering target having a thickness of 6 mm was formed by DC sputtering in an Ar gas atmosphere. SnTe
N, crystal nucleus supplying layer made of TiN or ZrN may, SnTe, Ti, sputtering data of each of the Zr - was formed by RF sputtering target in Ar-N ₂ mixed gas atmosphere. Ge
The phase transformation layer made of SbTe was formed by DC sputtering a target in an Ar gas atmosphere.

A sample without a crystal nucleus supply layer was also prepared. Then, the sample with and without the crystal nucleus supply layer is
The transmittance was measured while increasing the temperature at a rate of 50 ° C./minute with a He-Ne laser. When the phase transformation layer reaches the crystallization temperature, the transmittance of the sample sharply decreases, so that the change in the transmittance reveals the crystallization temperature. Table 13 shows the measured values of the crystallization temperature of each sample.

[0151]

[Table 13]

When there was no crystal nucleus supply layer, the crystallization temperature of GeSbTe as the phase transformation layer was 192 ° C. It is considered that the use of a material containing Te for the crystal nucleus supply layer lowers the crystallization temperature of the phase transformation layer, and is effective in generating crystal nuclei. TiN and ZrN
Has a NaCl-type crystal phase, but has no effect on crystal nucleation. Sb had no effect.

(Embodiment 15) In Embodiment 15, an example will be described in which the information recording medium 53 is manufactured using the material effective in generating crystal nuclei in Embodiment 14, and as-depo recording is performed.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ (80 mol% ZnS-20 mol% SiO ₂₎ was used as a protective layer.
₂ . Hereinafter, the same applies. ), 5 nm of GeN as an interface layer, 2 nm of a crystal nucleus supply layer, 10 nm of GeSbTe as a phase transformation layer, 5 nm of GeN as an interface layer, ZnS-20 mol% SiO ₂ as a protective layer, and an Ag alloy as a reflective layer in this order. A continuous film was formed. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate. Bi ₂ Te ₃ , Sb _{2
Te 3, Te, SnTe, SnTe} -PbTe, SnTe-Ag, SnTe-Se, SnTeN, PbTe, G
eSbTe eutectic or GeBiTe eutectic were used.

Next, the film forming conditions of each material will be described. ZnS-20 mol% SiO ₂ was formed by a RF sputtering method in an Ar gas atmosphere using ZnS-20 mol% SiO ₂ as a base material. Ge
N was deposited by RF sputtering in an Ar-N ₂ mixed gas atmosphere using Ge as a base material. The crystal nucleus supply layer was formed under the same conditions as in Example 1. The phase transformation layer made of GeSbTe is Ge
A film was formed by a DC sputtering method in an Ar-N ₂ mixed gas atmosphere using SbTe as a base material. The reflective film made of Ag alloy
A film was formed by a DC sputtering method in an Ar gas atmosphere using an Ag alloy as a base material. In the information recording medium of Example 15, the thicknesses of both the protective layers were strictly determined so that Ra was about 28% and Rc was about 10%.

The reversible optical information recording medium of Example 2 was evaluated using an evaluation drive equipped with a laser having λ = 660 nm and NA = 0.6. The evaluation items are the amplitude, noise level, and CNR of the 3T signal on the groove. The evaluation was performed under the condition that the linear velocity of the laser beam irradiation part was 8.2 m / s. Recording was performed by modulating the laser beam with high power Pp (mW) and low power Pb (mW).
FIG. 8 shows the modulated recording waveform. Regardless of the original state (as-dep
oAmorphous, initialized crystal phase, recording state), and amorphous phase and crystal phase are formed by modulating a laser beam, and new information is recorded. Here, Pr (mW) is a reproducing power.

By initializing a part of the annular area of the information recording medium, the initialization is not performed as-depo.
The s-depo amorphous region and the initialized crystal phase region were formed in the same plane. Then, it was determined whether as-depo recording was possible by comparing the CNRs of both state ranges. Since each medium had Ra of about 28% and Rc of about 10%, the address reading was good in both states, the servo was stable, and the CNR could be evaluated. 3T signal on the groove 1
Recorded times. Table 14 shows the evaluation results.

[0158]

[Table 14]

As is clear from Table 14, when the material containing SnTe or the material containing PbTe was used, the CNR in the as-depo amorphous region and the CNR in the crystal phase region were almost at the same level. .
If anything, the CNR was higher in the as-depo amorphous region than in the crystalline phase region by about a 1 dB lower noise level. It is considered that there is a slight noise rise due to the initialization.
When other materials including Te were used, the CNR in the as-depo amorphous region was about 3 to 5 dB lower than the CNR in the crystalline phase region, but 45
dB or more was obtained. From the above results, as-d
It turned out that epo recording was possible.

The melting point of GeSbTe as the phase transformation layer is about 620 ° C., and the material of the crystal nucleus supply layer other than SnTe and PbTe has a melting point of about 620 ° C.
620 ° C or lower. Therefore, during recording, the crystal nucleus supply layer is melted and mixed with the phase transformation layer, and the optical characteristics are changed, so the CNR is considered to be several dB lower. Therefore, it has been found that in the configuration in which the phase transformation layer is formed after the crystal nucleus supply layer, a material containing SnTe or a material containing PbTe is more preferable as the material for the crystal nucleus supply layer.

(Embodiment 16) In Embodiment 16, an example will be described in which an information recording medium 54 is manufactured using a material which has been effective in generating crystal nuclei in Embodiment 14, and as-depo recording is performed.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ was used as a protective layer, and GeN was used as an interface layer.
nm, 10 nm GeSbTe as phase transformation layer, 2n crystal nucleus supply layer
m, GeN 5 nm as an interface layer, ZnS-20 mol% SiO as a protective layer
_{2. An} Ag alloy was continuously formed as a reflective layer in this order. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate. Bi ₂ Te ₃ , Sb _{2
Te 3, Te, SnTe, SnTe} -PbTe, SnTe-Ag, SnTe-Se, SnTeN, PbTe, G
eSbTe eutectic or GeBiTe eutectic were used. The film forming conditions for each layer are the same as in Example 15.

A part of the annular region of the information recording medium was initialized, and an uninitialized as-depo amorphous region after film formation and a crystal phase region after initialization were formed in the same plane. And CN of both state areas
By comparing R, it was judged whether or not as-depo recording was possible.

The recording conditions and the evaluation conditions are the same as in the second embodiment. Table 15 shows the evaluation results.

[0165]

[Table 15]

From Table 15, it can be seen that the CNR in the as-depo amorphous region and the CNR in the crystal region of each material as the crystal nucleus supply layer are almost the same level, and recording on the as-depo amorphous is possible. It turned out to be. As described above, in the configuration in which the crystal nucleus supply layer is formed after the phase transformation layer, as-depo recording can be performed even when a material having a lower melting point than the phase transformation layer is used as the material of the crystal nucleus supply layer.

(Example 17) In Example 17, as-d
A crystal nucleus supply layer was formed using SnTe, which was found to be capable of epo recording, and the dependence of the crystal nucleus supply layer on film thickness and the number of recordings in as-depo recording were investigated. In Example 17, the information recording medium 53 was manufactured in the same manner as in Example 15. At this time, the thickness of the crystal nucleus supply layer of the information recording medium was changed from 0 nm to 7 nm every 0.5 nm for each sample.

A 3T signal was recorded once, twice and ten times in the uninitialized amorphous state. Evaluation conditions are the same as in Example 15. Table 16 shows the evaluation results.

[0169]

[Table 16]

As is clear from Table 16, when the thickness of the crystal nucleus supply layer was 2 nm or more, almost saturated CNR was obtained from one recording. When the film thickness is as thin as 1.5 nm or less, the CNR is small because the amplitude is small in one recording and the noise level is high in the two recordings.
Is low. The noise level decreases with the number of recordings,
Seven recordings were required to obtain a saturated CNR. Thick film
Above 4.5 nm, no saturated CNR was obtained at a recording power of 15 mW. It was found that when the crystal nucleus supply layer was thick, the recording sensitivity of the phase change layer was reduced. The thickness of the crystal nucleus supply layer capable of performing as-depo recording and having good recording sensitivity was about 2 nm to about 4 nm.

Therefore, in the information recording medium of Example 17, it was found that the thickness of the crystal nucleus supply layer is preferably from about 2 nm to about 4 nm.

Example 18 In Example 18, an experiment similar to that of Example 17 was performed on the information recording medium 54.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ was used as a protective layer, and GeN was used as an interface layer.
nm, GeSbTe 10 nm as phase transformation layer, crystal nucleus supply layer
SnTe, GeN 5 nm as an interface layer, ZnS-20mo as a protective layer
l% SiO ₂ and an Ag alloy as a reflective layer were continuously formed in this order.
After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate. The film thickness of SnTe, which is a crystal nucleus supply layer, was changed every 0.5 nm from 0 nm to 7 nm. Example 1
Table 17 shows the results of the same measurement as in 7.

[0174]

[Table 17]

As is clear from Table 17, when the thickness of the crystal nucleus supply layer was 2 nm or more, almost saturated CNR was obtained from one recording. At 5.5 nm or more, a saturated CNR could not be obtained at a recording power of 15 mW. Similarly to the result of Example 17, when the thickness of the crystal nucleus supply layer increases, the recording sensitivity of the phase change layer decreases. In the information recording medium of Example 18, the thickness of the crystal nucleus supply layer capable of performing as-depo recording and having good recording sensitivity was about 2 n.
m to about 5 nm. Therefore, in a configuration in which the crystal nucleus supply layer is stacked after the phase transformation layer, the thickness of the crystal nucleus supply layer is preferably about 2 nm to about 5 nm.

(Embodiment 19) In Embodiment 19, an example in which a reversible optical information recording medium 55 is manufactured will be described.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ as a protective layer and GeN as an interface layer were used.
nm, SnTe as the crystal nucleus supply layer 32, and GeSb as the phase transformation layer
Te as 10 nm, SnTe as the crystal nucleus supply layer 35, and as the interface layer
5 nm of GeN, ZnS-20 mol% SiO ₂ as a second protective layer, and an Ag alloy as a reflective layer were successively formed in this order. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate. As-depo recording was performed under the same conditions as in Example 17 except that the thicknesses of the crystal nucleus supply layers 32 and 35 were changed. Table 18 shows the evaluation results.

[0178]

[Table 18]

When the phase transformation layer was sandwiched between the crystal nucleus supply layers, the crystal nucleus supply layers 32 and 35 each had a thickness of 1 nm, and as-depo recording was possible. When the thickness of both crystal nucleus supply layers was 3 nm, the recording sensitivity was insufficient. Compared with the case where the crystal nucleus supply layer is provided on only one side of the phase transformation layer, the nucleation effect is considered to be synergistic when the crystal nucleus supply layer is provided on both sides of the phase transformation layer. Therefore, when crystal nucleus supply layers are formed on both sides of the phase transformation layer, the thickness of the nucleus crystal nucleus supply layer may be about half, more preferably about 1 nm to about 2 nm.

(Embodiment 20) In the embodiment 20, the information recording medium 53
An example will be described in which the relationship between the film thickness of the crystal nucleus supply layer, the film formation rate of the phase change layer, and the state after the film formation of the phase change layer is examined.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO2 was used as a protective layer, and GeN was used as an interface layer.
nm, SnTe as crystal nucleus supply layer, GeSbTe as phase transformation layer
10 nm, GeN 5 nm as an interface layer, ZnS-20 mol% as a protective layer
SiO ₂ and an Ag alloy as a reflective layer were continuously formed in this order. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate.

In the information recording media of each sample, the film formation rate r (nm / min) of the phase transformation layer was different, and was changed from 5 nm / min to 60 nm / min. The thickness d1 of the crystal nucleus supply layer is 2 nm and 5 nm. d1 = 2n
The information recording medium of m is optically designed so that the reflectance Ra in the amorphous region is approximately 28% and the reflectance Rc in the crystalline phase region is approximately 10%, and d1
= 5 nm information recording medium has a reflectance Ra of about 30% in the amorphous region,
The optical design was performed so that the reflectance Rc in the crystal phase region was about 12%. After bonding, initialize a part of the annular area of the information recording medium, and do not initialize after film formation on the same plane.
o An amorphous region and a crystal phase region after initialization were formed, and the reflectance in both state regions was measured.

The reflectivity was measured using a drive for evaluation equipped with a laser of λ = 660 nm and NA = 0.6, with the focus servo operated at a linear velocity of 8.2 m / s, and the mirror portion formed on the substrate. The reflectance was measured. Table 19 shows the relationship between the deposition rate of the phase transformation layer and the reflectance.

[0184]

[Table 19]

From Table 19, when d1 = 2 nm, r ≧ 20 (nm /
Minutes), the reflectance of the uninitialized area is about 28%,
It can be determined that the state after film formation is amorphous. On the other hand, r <2
When it is 0 (nm / min), the reflectance is only about 10% or more, and it is considered that at least a part of the phase transformation layer is crystallized during film formation.

When d1 = 5 nm, r ≧ 50 (nm / min)
In this case, the reflectance in the uninitialized region is about 30%, and it can be determined that the state after film formation is amorphous. On the other hand, r <50
At (nm / min), it is considered that at least a part of the phase transformation layer is crystallized during film formation. As described above, the state after the film formation of the phase change layer is determined by the film formation speed of the phase change layer and the film thickness of the crystal nucleus supply layer. In order to form the phase change layer in an amorphous state, it is preferable to increase the film formation rate of the phase change layer as the crystal nucleus supply layer is thicker.

(Example 21) In Example 21, the information recording medium 53 was used.
Using an information recording medium where Rc is almost 0%,
If the -depo recording could be done, we checked whether the drive could provide servo stability and good address readability.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ was used as a protective layer, and GeN was used as an interface layer.
nm, 2 nm of SnTe as a crystal nucleus supply layer, GeS as a phase transformation layer
bTe 10 nm, GeN 5 nm as an interface layer, ZnS-2 as a protective layer
0 mol% SiO ₂ and an Ag alloy as a reflective layer were continuously formed in this order. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate.

The film thickness of both protective layers is strictly determined, and Ra (reflectance of the information recording medium when the phase transformation layer is amorphous)> R
Four types of information recording media of c (reflectance of the information recording medium when the phase transformation layer is a crystalline phase) were produced.

A part of the annular region of the information recording medium is initialized, and an uninitialized as-depo amorphous region (Ra) and a crystal phase region (Rc) after initialization are formed in the same plane. Then, the servo stability, readability of address and CNR in both states were evaluated. Table 20 shows the evaluation results.

[0191]

[Table 20]

As shown in Table 20, the Rc of the information recording medium is 5.
In the case of 3%, the address was difficult to read in the initialized crystal phase region. When Rc was 0.9%, the tracking servo was hard to operate in the initialized crystal phase region.

On the other hand, if Rc> 10 (%), the servo characteristics were stable even in the crystal phase region, and the address readability was good. As described above, if the information recording medium optically designed with Ra> Rc is initialized, the lower limit of Rc is restricted. On the other hand, in the as-depo amorphous region that was not initialized after the film formation, the address readability was good regardless of the value of Rc. Unless initialized, the reflectivity of the address portion is stored in Ra, so the lower limit of Rc is not restricted. As described above, the use of the phase transformation layer in which the crystal nucleus supply layer and the phase transformation layer are stacked enables as-depo recording, and the reflectance of the address portion is sufficiently large with Ra even when Rc is close to 0%. Since it was kept, it was verified that the address of the information recording medium could be read and the servo was stabilized. Good CNR was also obtained.

(Embodiment 22) In Embodiment 22, an example in which an information recording medium is manufactured in the same manner as in Embodiment 21 and the reflectance is measured using a laser of λ = 405 nm will be described.

To manufacture the information recording medium 53, ZnS-20 mol% SiO ₂ was used as a protective layer, GeN was 5 nm as an interface layer, SnTe was 2 nm as a crystal nucleus supply layer, GeSbTe was 12 nm as a phase transformation layer,
GeN of 5 nm as an interface layer, ZnS-20 mol% SiO ₂ as a protective layer,
An Ag alloy was continuously formed as a reflective layer in this order. After film formation,
An ultraviolet curable resin was spin-coated on an Ag alloy and bonded to a dummy substrate.

For the protective layer, the interface layer, the crystal nucleus supply layer, the phase transformation layer, and the reflection layer, the complex refractive index for a laser beam of λ = 405 nm was measured by ellipsometry. The thickness of each layer was strictly determined so that the absolute value of (ΔR = Rc-Ra) was sufficiently large. The 3T signal was recorded once on the grooves in the as-depo amorphous region and the crystalline phase region, and the CNR was measured. Table 21 shows the measurement results.

[0197]

[Table 21]

As-depo recording was possible even at a short wavelength of λ = 405 nm. When as-depo recording was possible, the servo was stable and the address readability was good even if Rc was low. As described above, it has been verified that the use of a phase transformation layer in which a crystal nucleus supply layer and a phase transformation layer are stacked enables as-depo recording using a short-wavelength laser beam and can also be performed for high-density recording. Was.

(Embodiment 23) In Embodiment 23, the information recording medium 53 is used.
The following describes an example in which AgInSbTe is used as a phase transformation layer and as-depo recording is performed.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ as a protective layer and GeN as an interface layer were formed.
nm, SnTe as crystal nucleus supply layer, AgInSb as phase transformation layer
Te 10 nm, GeN 5 nm as an interface layer, ZnS-20 as a protective layer
A mol% SiO ₂ and an Ag alloy as a reflective layer were continuously formed in this order. ZnS-20 mol% SiO ₂ was formed by RF sputtering in an Ar gas atmosphere using ZnS-20 mol% SiO ₂ as a base material. GeN was formed by performing RF sputtering in a Ar-N ₂ mixed gas atmosphere using Ge as a base material. The crystal nucleus supply layer was formed by subjecting the base material to DC sputtering in an Ar gas atmosphere. AgInSbTe was formed by performing DC sputtering in an Ar gas atmosphere using AgInSbTe as a base material. The Ag alloy was formed by DC sputtering in an Ar gas atmosphere using the Ag alloy as a base material. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate. The information recording medium of each sample has a different crystal nucleus supply layer thickness. 0.5nm from 0nm to 7nm
Changed every time. Also, the 3T signal is changed to an as-depo amorphous state.
Twice, twice and ten times were recorded. The results are shown in Table 22.

[0201]

[Table 22]

As shown in Table 22, the thickness of the crystal nucleus supply layer was
It was found that if the thickness was 2 nm or more, almost saturated CNR could be obtained from one recording. When the thickness of the crystal nucleus supply layer was as thin as 1.5 nm or less, the CNR was low because the amplitude was small in the single recording and the noise level was high in the double recording. Also,
Although the noise level decreased with the number of recordings, seven recordings were required to obtain a saturated CNR. The thickness of the crystal nucleus supply layer is
When the thickness was 4.5 nm or more, a saturated CNR was not obtained at a recording power of 15 mW. The recording sensitivity of the phase change layer decreases as the thickness of the crystal nucleus supply layer increases. The thickness of the crystal nucleus supply layer, which enables as-depo recording and improves the recording sensitivity, is about 2 nm.
From about 4 nm. Even if AgInSbTe is used for the phase transformation layer,
Depo recording was possible, and the effect of SnTe as a crystal nucleus supply layer was verified.

It has been reported that AgInSbTe is a mixture of InSb and AgSbTe ₂ , and it is considered that since AgSbTe ₂ has a NaCl-type structure, the formation of crystal nuclei by SnTe is likely to be promoted.

(Example 24) In Example 24, Ag, Sn,
An example in which the information recording medium 53 is manufactured by using a material to which any one of Cr, Pb, Bi, Pd, Se, In, Ti, Zr, Au, Pt, Al, and Mn is added as a phase transformation layer will be described.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ was used as a protective layer, and GeN was used as an interface layer.
nm, 2 nm of SnTe as a crystal nucleus supply layer, GeS as a phase transformation layer
bTe + M (M is Ag, Sn, Cr, Pb, Bi, Pd, Se, In, Ti, Zr, Au, Pt, Al
Or Mn) is 10 nm, and GeN is 5n as an interface layer.
m, ZnS-20 mol% SiO ₂ as a protective layer, and an Ag alloy as a reflective layer were continuously formed in this order. After film formation, UV curable resin is Ag
It was spin-coated on the alloy and bonded to a dummy substrate.

Table 23 shows the results of a recording experiment performed on the above samples in an as-depo state. In Table 23,
(△ CNR (dB)) = (CNR of 10th recording (dB))-(CNR of 1st recording
(dB)).

[0207]

[Table 23]

As shown in Table 23, almost any saturated CNR was obtained from the first time, regardless of which element was added to GeSbTe. Therefore, it was found that as-depo recording was possible even when the material represented by the composition formula GeSbTe + M was used as the phase transformation layer.

(Example 25) [0209] In Example 25, an example in which an information recording medium 53 having a different thickness of the phase transformation layer was manufactured and an as-depo recording experiment was performed will be described.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ was used as a protective layer, and GeN was used as an interface layer.
nm, 2 nm of SnTe as a crystal nucleus supply layer, GeS as a phase transformation layer
bTe, GeN 5 nm as an interface layer, ZnS-20 mol as a protective layer
% SiO ₂ and an Ag alloy as a reflective layer were continuously formed in this order.
The thickness of the phase transformation layer was changed from 2 nm to 25 nm. After film formation,
An ultraviolet curable resin was spin-coated on an Ag alloy and bonded to a dummy substrate. After bonding, initialize a part of the annular area of the information recording medium, not initialized after film formation
The -depo amorphous region and the crystal phase region after initialization were formed in the same plane.

The recording conditions and the evaluation conditions were the same as those in Example 15. Each of the 3T signals was recorded once on the groove in both the state ranges, and the CNR was measured. Table 24 shows the measurement results.

[0212]

[Table 24]

[0213] As shown in Table 24, the thickness of the phase transformation layer was 2 nm.
In the case of, it did not crystallize. 3nm thickness of phase transformation layer
As-depo recording is possible from
At 5 mW, the CNR was not saturated and the recording sensitivity was insufficient. as-depo
For recording, a phase transformation layer of 3 nm to 20 nm is practically usable.
A preferred thickness is from 15 nm to 15 nm.

(Embodiment 26) In the embodiment 26, the information recording medium 53 is used.
The following describes an example of examining the effect of the crystal nucleus supply layer on the recording characteristic reliability.

On a polycarbonate substrate having a guide groove, ZnS-20 mol% SiO ₂ was used as a protective layer, and GeN was used as an interface layer.
nm, 2 nm of SnTe as a crystal nucleus supply layer, GeS as a phase transformation layer
bTe 10 nm, GeN 5 nm as an interface layer, ZnS-2 as a protective layer
0 mol% SiO ₂ and an Ag alloy as a reflective layer were continuously formed in this order. After film formation, an ultraviolet curable resin was spin-coated on the Ag alloy and bonded to a dummy substrate. The information recording medium of Example 26 was manufactured so that Ra> Rc. In addition, signal recording was started in an as-depo amorphous state without initializing the phase change layer.

After the information recording medium of Example 26 was prepared, the medium was left in an environment of 90 ° C. and 20% RH for 24 hours, and the change in jitter before and after the standing was measured. The measurement was performed for three types, Test 1, Test 2 and Test 3. In test 1, as-de
The po was recorded and measured, and only the measurement was performed after standing. Exam 2
Then, measurement was performed by recording as-depo before leaving, and overwriting after leaving. In test 3, before being left unrecorded,
After the standing, as-depo recording and measurement were performed.

The information recording medium was evaluated with a laser having λ = 660 nm and NA = 0.6. The jitter value of the 3T signal between and on the grooves was evaluated. The 3T signal was recorded once. The linear velocity is 8.2m / s. Table 25 shows the jitter difference between the grooves before and after standing, and Table 26 shows the jitter difference on the groove. Here, (jitter difference) =
(Jitter value after standing)-(Jitter value before standing).

[0218]

[Table 25]

[0219]

[Table 26]

As shown in Tables 25 and 26, the jitter difference between Test 1, Test 2 and Test 3 was 2% or less, either between the grooves or on the grooves. Reliability was good. By laminating the crystal nucleus supply layer and the phase transformation layer (the part where reversible phase transformation occurs) in this way, two effects are obtained: as-depo recording is possible and the reliability of overwriting can be secured. Was.

The embodiments of the present invention have been described above with reference to the examples. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments based on the technical concept of the present invention.

For example, the information recording medium is not limited to the configuration of the above embodiment, and may be any information recording medium having a phase transformation layer in which a crystal nucleus supply layer and a phase transformation layer are laminated.

[0223]

As described above, since the information recording medium of the present invention includes the phase transformation layer in which the crystal nucleus supply layer and the phase transformation layer are stacked, information can be recorded easily and reliably. it can. Further, the information recording medium of the present invention can perform as-depo recording without requiring an initialization step. In particular, Ra> Rc
In the information recording medium of the above, the effect that the address readability and the servo stability are good even when Rc is close to 0% can be obtained.

Further, the method for manufacturing an information recording medium of the present invention can easily manufacture the information recording medium of the present invention.

Further, according to the information recording medium recording / reproducing method of the present invention, information can be recorded easily and reliably.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing one configuration example of an information recording medium of the present invention.

FIG. 2 is a partial sectional view showing another configuration example of the information recording medium of the present invention.

FIG. 3 is a partial cross-sectional view showing one configuration example of a two-layer information recording medium in the information recording medium of the present invention.

4 (a) to 4 (c) show the temperature dependence of transmittance for judging the phase structure of the crystallization-enhancing layer or the recording layer laminated on the crystallization-enhancing layer of the present invention. It is a graph shown. The horizontal axis is temperature and the vertical axis is transmittance. (A) is a graph when the phase structure is amorphous. (B) is a graph in the case where the phase structure is a mixed state of an amorphous phase and a crystalline phase.
(C) is a graph when the phase structure is a crystalline phase.

FIG. 5 is a partial cross-sectional view showing another configuration example of the information recording medium of the present invention.

FIG. 6 is a partial sectional view showing another configuration example of the information recording medium of the present invention.

FIG. 7 is a partial sectional view showing another configuration example of the information recording medium of the present invention.

FIG. 8 is a diagram showing a modulation waveform of a laser beam used for recording in the recording / reproducing method of the information recording medium of the present invention, wherein the horizontal axis represents time and the vertical axis represents laser power.

[Explanation of symbols]

 50,51,52,53,54,55,56 Information recording medium 1 Substrate 2,6 Protective layer 3 Crystallization enhancing layer 4 Phase transformation layer 5,31,34,36,38 Recording layer 7 Reflective layer 8 Adhesive layer 9 Dummy substrate 10, 11 Interface layer 12 Optical absorption correction layer 13 First substrate side 14, 19 First protective layer 15, 18 First interface layer 17 First recording layer 20 First information recording medium 21 Separation Layer 22, 26 Second protective layer 23, 25 Second interface layer 27 Laser beam 28 Second substrate 29 Second information recording medium 32, 35 Crystal nucleus supply layer 33, 37 Phase transformation layer

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) G11B 7/004 G11B 7/26 531 5D121 7/26 531 7/30 Z 7/30 B41M 5/26 X (72) Invention Person Hideki Kitaura 1006 Kazuma, Kazuma, Osaka Pref. F-term (reference) Matsushita Electric Industrial Co., Ltd. BA06 BA35 BB01 BB12 BB13 CA07 CA12 JA01 LA19 5D029 HA05 HA07 JA01 JB03 JB05 JB16 JB42 JC20 LA11 LB01 LB12 MA02 MA03 NA13 NA15 RA02 RA16 RA49 5D090 AA01 BB05 BB12 CC11 DD01 5D121 AA01 EA07 GG01

Claims (42)

[Claims] 1. An information recording medium having at least a recording layer formed on a substrate, wherein said recording layer causes a reversible phase transformation between a crystalline state and an amorphous state by irradiation with a light beam. A phase-change layer, and a layer that serves as a crystallization-capability improving layer that improves the crystallization capability of the phase-transform layer, wherein the crystallization-capability improving layer is formed before the phase-change layer is formed, An information recording medium, wherein the transformation layer causes crystal nucleation and crystal growth during film formation, and at least a part of the phase transformation layer is formed in a crystal phase after film formation. 2. An energy for crystallizing the phase change layer when the crystallization ability improving layer is formed, and crystallization of the phase change layer when the crystallization ability improvement layer is not formed. 2. The information recording medium according to claim 1, wherein A <B, where B is the energy to be applied. 3. The information recording medium according to claim 1, wherein the crystallization ability improving layer is at least one selected from tellurides and halides. 4. The method according to claim 1, wherein the telluride is SnTe, PbTe, Te, Sb ₂ Te ₃ , Bi ₂ T
e ₃ , GeTe-Sb ₂ Te ₃ eutectic composition (hereinafter referred to as GeSbTe eutectic) and Ge
Te-Bi ₂ Te ₃ eutectic composition (hereinafter, GeBiTe eutectic) is at least one selected from the group consisting of ZnF ₂ , AlF ₃ , K
_{F, CaF 2, NaF, BaF} 2, MgF 2, LaF 3, the information recording medium according to claim 3 is at least one selected from LiF. 5. The information recording medium according to claim 1, wherein the crystal structure of the phase transformation layer is a rock salt type. 6. The information recording medium according to claim 1, wherein the phase transformation layer contains GeSbTe. 7. The information recording medium according to claim 1, wherein the crystallinity improving layer has a crystal structure of a rock salt type. 8. The information recording medium according to claim 3, wherein the thickness dt (nm) of the crystallinity improving layer selected from telluride is 1 ≦ dt ≦ 10. 9. The information recording medium according to claim 3, wherein the thickness df (nm) of the crystallinity improving layer selected from halides is 1 ≦ df ≦ 20. 10. The information recording medium according to claim 1, wherein a protective layer and a reflective layer are further laminated on the recording layer. 11. The information recording medium according to claim 10, wherein a light absorption correction layer is formed between the protective layer and the reflection layer. 12. The method according to claim 1, wherein no initialization of the recording layer is required.
12. The information recording medium according to any one of items 1 to 11. 13. A two-layer substrate comprising a first substrate and a second substrate, wherein the recording layer of claim 1 is formed on both substrates, and the two substrates are bonded with the two substrates facing outward. The information recording medium according to any one of claims 1 to 12, which is an information recording medium. 14. The information recording medium according to claim 13, wherein the recording layer according to claim 1 is formed on the first substrate side. 15. The method for manufacturing an information recording medium according to claim 1, wherein a crystallization-capability improving layer is formed, and then, when forming a phase transformation layer, the phase transformation layer is formed. A method for producing an information recording medium, characterized in that a film is formed in a range of 5 ≦ r ≦ 20 when a film speed is r (nm / min). 16. The method according to claim 15, wherein the phase transformation layer is crystallized during the formation of the phase transformation layer. 17. An information recording medium comprising at least a recording layer on a substrate, wherein said recording layer undergoes a reversible phase transformation between a crystalline state and an amorphous state upon irradiation with a light beam. An information recording medium comprising: a layer; and a crystal nucleus supply layer laminated on the phase transformation layer and promoting crystallization of the phase transformation layer. 18. The information recording medium according to claim 17, wherein the phase transformation layer and the crystal nucleus supply layer are uniformly formed on one surface. 19. The information recording medium according to claim 17, wherein the phase transformation layer and the crystal nucleus supply layer are formed in an island shape. 20. The information recording medium according to claim 17, wherein the phase transformation layer is in an amorphous state after film formation. 21. The information recording medium according to claim 17, wherein the crystal nucleus supply layer and the phase transformation layer are laminated in this order from the substrate side. 22. A phase change layer further includes a second crystal nucleus supply layer for promoting crystallization of the phase change layer, wherein the phase change layer and the second crystal nucleus supply layer are stacked in this order from the substrate side. The information recording medium according to any one of claims 17 to 21. 23. The information recording medium according to claim 17, wherein the phase transformation layer and the crystal nucleus supply layer are laminated in this order from the substrate side. 24. The transition temperature (hereinafter referred to as crystallization temperature) Tx1 (° C.) of the crystal nucleus supply layer from the amorphous phase to the crystal phase, and the crystallization temperature Tx2 (° C.) of the phase transformation layer are expressed as Tx2> The information recording medium according to any one of claims 17 to 23, which satisfies a relationship of Tx1. 25. The information recording medium according to claim 17, wherein the melting point Tm1 (° C.) of the crystal nucleus supply layer and the melting point Tm2 (° C.) of the phase transformation layer satisfy the relationship of Tm1> Tm2. . 26. The information recording medium according to claim 17, wherein the crystal nucleus supply layer is a compound containing Te. 27. The information recording medium according to claim 26, wherein the crystal nucleus supply layer contains at least one selected from SnTe and PbTe. 28. The crystal nucleus supply layer is composed of SnTe-M (where M is N,
Ag, Cu, Co, Ge, Mn, Nb, Ni, Pd, Pt, Sb, Se, Ti, V, Zr and PbTe
27. The information recording medium according to claim 26, comprising at least one element or compound selected from the group consisting of: 29. The information recording medium according to claim 28, wherein the content of M is in a range of 0.5 to 50 atom%. 30. The information recording medium according to claim 17, wherein the phase transformation layer is made of a chalcogen-based material. 31. A phase transformation layer comprising: GeTe, GeSbTe, TeSnSe, InSbT
31. The information recording medium according to claim 17, which comprises at least one selected from e, GeBiTe, and AgInSbTe. 32. A phase transformation layer comprising GeSbTe, Ag, Sn, Cr, Mn, P
The information recording medium according to any one of claims 17 to 31, comprising at least one element selected from b, Bi, Pd, Se, In, Ti, Zr, Au, Pt, Al, and N. 33. The thickness d1 (nm) of the crystal nucleus supply layer and the thickness d2 (nm) of the phase transformation layer satisfy a relationship of d2> d1.
33. The information recording medium according to any one of 7 to 32. 34. The thickness d1 (nm) of the crystal nucleus supply layer is 0.3 <d1
The information recording medium according to any one of claims 17 to 33, wherein the information recording medium satisfies a relationship of ≤5. 35. The information recording medium according to claim 17, wherein the thickness d2 (nm) of the phase transformation layer satisfies the relationship of 3 ≦ d2 ≦ 20. 36. The reflectance Rc (%) of the information recording medium when the phase transformation layer is a crystalline phase, and the reflectance Ra (%) of the information recording medium when the phase transformation layer is amorphous. The information recording medium according to any one of claims 17 to 35, wherein satisfies a relationship of Ra> Rc. 37. The method for manufacturing an information recording medium according to claim 17, wherein said recording layer is formed by first forming a phase transformation layer using a vapor phase thin film deposition method. ,
Next, a method for manufacturing an information recording medium, comprising forming a crystal nucleus supply layer. 38. A vapor phase thin film deposition method comprising: a vacuum deposition method, a sputtering method, an ion plating method, and a CVD (Chemical V) method.
apor Deposition) and MBE (Molecular Beam Epitaxy)
38. At least one method selected from laws.
3. The method for manufacturing an information recording medium according to claim 1. 39. The method according to claim 37, wherein the step of forming the phase transformation layer is performed under the condition that the phase transformation layer becomes amorphous.
3. The method for manufacturing an information recording medium according to claim 1. 40. The method for manufacturing an information recording medium according to claim 37, wherein the conditions under which the phase change layer becomes amorphous are a film formation rate of r (nm / min) and r ≧ 30. . 41. The recording / reproducing method for an information recording medium according to claim 17, wherein said recording layer includes a phase transformation layer and a crystal nucleus supply layer, and a laser beam is applied to said recording layer. A method for recording / reproducing information on an information recording medium, wherein the information is recorded by irradiating the phase transformation layer to transform the phase. 42. A phase change layer is formed in an amorphous state,
42. The recording / reproducing method for an information recording medium according to claim 41, wherein recording of information is started in an amorphous state without crystallization.