JP2001344823A - Optical information recording medium, method for producing the same and recording and reproducing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high density optical information recording medium capable of suppressing the erasure of adjacent information when recording is carried out at a higher density and to provide a method for producing the medium and recording and reproducing methods for the medium. SOLUTION: The optical information recording medium has at least a recording layer whose optical characteristic can be reversibly varied by irradiation with laser light, a light absorbing layer and a reflecting layer. The complex index of refraction n-ik of the light absorbing layer at the wavelength of the laser light satisfies the conditions A; 0<n<2.5 and 0<k<=5, the conditions B; 2.5<=n<=6.0 and 3.5<=k<=5.0 or the condition C; 5<k<=8 and the wavelength of the laser light is in the range of 300-500 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium capable of recording / reproducing and rewriting information at high density and high speed by using optical means such as laser beam irradiation, and a method of manufacturing the same. It relates to the recording / reproducing method.

[0002]

2. Description of the Related Art Optical information recording media such as magneto-optical recording media and phase-change recording media are known as media capable of recording and rewriting information at a high capacity and at a high speed. These optical recording media utilize a difference in optical characteristics of the recording material caused by locally irradiating the recording material with a laser beam as recording.

[0003] These optical information recording media have a great advantage that they can be randomly accessed as required and are also highly portable, and thus their importance is increasing in the advanced information society. ing. For example, recording and preserving personal data and video information through a computer, medical fields, academic fields, portable digital video recorder recording media, home video tape recorder replacement, etc. Attempts have been made to use it. At present, these optical information recording media are required to achieve higher capacities (higher densities) and higher speeds in accordance with higher performance of applications and higher performance of image information.

[0004] As means for achieving higher densification,
Conventionally, shortening the wavelength of laser light used for recording or increasing the NA (numerical aperture) of laser light has been proposed. In each of these cases, it is possible to reduce the minimum spot diameter of the laser beam, so that it is possible to record a smaller mark, and in principle, higher density writing is possible in the in-plane direction of the recording material. . However, when a signal is written at a very high density, when a signal is rewritten, the adjacent mark already written is thermally or optically affected and the adjacent mark is erased. Is known to easily occur.

There have been several attempts to improve the characteristics of a medium by providing a light absorbing layer. For example, Japanese Patent Application Laid-Open No. 5-159360 discloses a technique for improving the overwrite erasing rate by providing a recording layer, an absorption layer, and a heat dissipation layer. According to the present invention, it is disclosed that by causing light absorption in the absorption layer, the difference in absorptance between different optical states of the recording layer can be adjusted, and the overwrite erasure rate is improved. However, in the present invention, the main purpose is to adjust the light absorption in the recording layer, and there is no mention of a device for reducing the aforementioned adjacent erasure at the blue wavelength. Further, when performing high-density recording at a blue wavelength, the optimum optical constant range and absorptance to be taken by the light absorbing layer are not considered. In the present invention, the absorption layer is made of Ti, Ni,
It is a material such as metal such as W that has absorption characteristics for the used laser light. However, by controlling the thermal conductivity of the absorption layer, the heat generated in the absorption layer is adjusted to improve the recording sensitivity. Not stated.

[0006] For example, Japanese Patent Application Laid-Open No. 8-329525 discloses a technique in which two reflective layers are provided so that the reflective layers can be repeated many times. However, even in the present invention, reduction of adjacent erasure when performing high-density recording at a blue wavelength is not described, and no consideration is given to an optimum optical constant range to be taken by the light absorbing layer at this time.

[0007]

When the distance between adjacent marks is further shortened to achieve higher density, when signals are rewritten, thermal or optical influences on already written adjacent marks are made. And erases the adjacent mark, which is a problem of so-called adjacent erasure. In particular, when high-density recording is performed with a smaller spot diameter using a laser beam in the blue wavelength region, which has been developed in recent years, this adjacent erasure is a major problem. When adjacent erasure occurs, even if recording with a smaller spot diameter is possible in principle, it is practically impossible to provide a medium with a higher density.

Further, in order to reduce the adjacent erasure, even if the medium is provided with a Si-based or Ti-based absorption layer which can be conventionally used at a red wavelength, the optical and thermal characteristics are not good. There is a problem that it is sufficient and the adjacent erase cannot be reduced.

[0009] The present invention solves the above-mentioned problems, and performs higher-density recording using a laser in a blue wavelength range.
It is an object of the present invention to provide a medium capable of reducing adjacent erasure. This makes it possible to realize a higher density recording medium.

[0010]

In order to solve the above-mentioned problems, an optical information recording medium according to the present invention comprises a recording layer whose optical characteristics can be reversibly changed by irradiation with a laser beam, a light absorbing layer, and a reflective layer. And the complex refractive index n-ik of the light absorbing layer at the wavelength of the laser light is such that condition A: 0 <n <2.5 and 0 <k ≦ 5, condition B: 2.5 ≦
n ≦ 6.0 and 3.5 ≦ k ≦ 5.0, and condition C: 5 <
It satisfies one of the conditions selected from k ≦ 8, and the wavelength of the laser light is in a range of 300 nm to 500 nm.

As a result, even when the interval between adjacent marks is very small, adjacent erasure at the time of writing can be reduced, and a higher density optical information recording medium can be realized.

More preferably, an interface layer is provided above and below the recording layer. According to this preferred example, sufficient erasing characteristics can be obtained even when recording is performed at a higher density, and the effect of reducing adjacent erasing according to the present invention can be more remarkably exhibited.

The thermal conductivity of the light absorbing layer at 800 K is 0.01 W / (m · K) or more and 5.0 W / (m · K).
K) It is preferably the following. This makes it possible to maintain an optimal heat balance at the time of heat generation due to mark writing, and more effectively reduce the adjacent erasure.

The light absorbing layer is preferably in an amorphous state. According to this preferred example, it is possible to easily satisfy the above-described preferred range of the thermal conductivity,
Adjacent erasure can be reduced more effectively.

The light absorbing layer is made of In-Sb, Sn-T
e, Cr-Te, Al-Sb, Pb-Te, Au, A
g, Cu, Ni, Cr, Pt, Nb, Pd, Sn, S
It is preferable to be formed from a material containing at least one of b, Bi, In, and Zn. According to this preferred example, the complex refractive index of the light absorbing layer can easily satisfy the above-mentioned favorable range.

It is preferable that the light absorbing layer is formed of a material containing Ge. According to this preferred example,
The complex refractive index and the thermal conductivity of the light absorbing layer can easily satisfy the above-mentioned favorable ranges, and the effects of the present invention can be more easily obtained.

It is preferable that the light absorbing layer is formed of a material containing at least one of nitrogen, oxygen and carbon. According to this preferred example, it is possible to easily satisfy the above-mentioned preferable range of the thermal conductivity, and it is possible to more effectively reduce adjacent erasure.

The light absorbing layer has a thickness of 5 nm or more and 60
nm or less. According to this preferred example, adjacent erasure can be more easily reduced.

Preferably, at least one heat insulating layer is provided between the light absorbing layer and the recording layer. According to this preferred example, it is possible to maintain an optimal heat balance, and it is possible to more effectively obtain the effect of reducing adjacent erasure.

Preferably, the heat insulating layer is formed of a material containing at least Si and O. According to this preferred example, it is possible to more easily obtain the effect of the heat insulating layer of blocking heat.

It is preferable that the reflection layer is provided in contact with the light absorption layer. According to this preferred example, the amount of heat generated in the light absorption layer is effectively cooled by the reflection layer, so that adjacent erasure can be more significantly reduced.

The recording layer preferably contains at least one of Ge, Sb, In, and Te. According to this preferred example, the optical property difference between the states having different optical properties can be easily increased, so that
Recording at higher density is easily possible, and the effect of reducing adjacent erasure according to the present invention is particularly remarkably obtained.

It is preferable that the recording layer contains N.
According to this preferred example, the thermal conductivity in the recording film surface can be reduced, so that the effect of reducing adjacent erasure can be more remarkably obtained.

The thickness of the recording layer is 1 nm or more and 15 n
m or less. This makes it possible to more effectively reduce adjacent erasure, and the effect obtained by the present invention is particularly remarkably obtained.

In order to solve the above-mentioned problems, a method for manufacturing an optical information recording medium according to the present invention comprises a step of producing a recording layer whose optical characteristics can be reversibly changed by irradiation with a laser beam; And a step of forming a reflective layer, wherein the complex refractive index n-ik of the light absorbing layer at the wavelength of the laser light is such that the condition A: 0 <
n <2.5 and 0 <k ≦ 5, Condition B: 2.5 ≦ n ≦ 6.
0 and 3.5 ≦ k ≦ 5.0, and condition C: any one selected from 5 <k ≦ 8 is satisfied, and the wavelength of the laser light is in the range of 300 nm to 500 nm. And As a result, the adjacent erase characteristics are excellent,
In addition, it is possible to manufacture an optical information recording medium capable of increasing the density.

It is preferable that the step of forming the reflective layer is provided immediately before or immediately after the step of forming the light absorbing layer. According to this preferred example, the effect of reducing adjacent erasure according to the present invention can be more remarkably obtained.

Next, in order to solve the above-mentioned problems, a recording / reproducing method for an optical information recording medium according to the present invention is characterized in that a substrate is reversibly changed between an amorphous state and a crystalline state by laser light irradiation. At least a recording layer, a light-absorbing layer, and a reflective layer, and the complex refractive index n-ik of the light-absorbing layer at the wavelength of the laser light is: Condition A: 0 <n <
2.5 and 0 <k ≦ 5, condition B: 2.5 ≦ n ≦ 6.0 and 3.5 ≦ k ≦ 5.0, and condition C: any condition selected from 5 <k ≦ 8 Is a method of recording, reproducing, and erasing information using an optical information recording medium that satisfies the following conditions.The laser beam is narrowed down to a small spot by an optical system, and a local part of the recording layer is amorphous by laser irradiation. The power level for generating an amorphous state that can be reversibly changed to a state is P1, the power level for generating a crystalline state that can be reversibly changed to a crystalline state by laser irradiation is P2, and any of the power levels P1 and P2. The optical power of the recording mark is not affected by the laser irradiation at that power level, and the reflectance is sufficient to reproduce the recording mark from the medium by the irradiation. When the level is a reproduction power level P3, information is recorded and erased by appropriately modulating the power of the laser light between the levels P1 and P2, and the laser light of P3 power is irradiated. It is characterized in that information recording and reproduction are performed, and the wavelength of the laser light when irradiating the laser light at the levels P1 and P2 is in the range of 300 nm to 500 nm.

As a result, even if the mark interval is further reduced, adjacent erasure can be reduced.
It is possible to provide a recording / reproducing method for an optical information recording medium capable of recording with higher density.

The amorphous state generating power level P
1 is preferably 10 mW or less. According to this preferred example, it is possible to reduce the amount of excess heat input into the recording film surface, and it is possible to remarkably obtain the effect of adjacent erasure according to the present invention.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. FIG. 1 shows an example of the layer configuration of the optical information recording medium according to the present invention. However, the present invention is not limited to the above configuration. For example, in FIG.
A configuration in which the interface layer 3 or the interface layer 5 or both are not provided, or a configuration in which the reflective layer 8 includes two reflective layers,
Or a configuration having another layer between the substrate 1 and the protective layer 2,
Alternatively, a configuration in which the protective layer 2 is entirely replaced by the interface layer 3, a configuration in which the heat insulating layer 6 is entirely replaced by the interface layer 5, or a configuration in which another layer is provided on the reflection layer 8 on the side opposite to the laser incidence.
It can be applied to various configurations.

In FIG. 1, a substrate 1 is made of polycarbonate, polymethyl methacrylate, polyolefin resin,
Alternatively, it is preferable that the guide groove is made of glass or the like and has a guide groove for guiding a laser beam.

The protective layer 2 is provided mainly for the purpose of protecting the recording material and adjusting the optical characteristics such as enabling effective light absorption in the recording layer. Examples of the material of the protective layer 2 include sulfides such as ZnS, selenides such as ZnSe, and Si.
Oxides such as -O, Al-O, Ti-O, Ta-O, Zr-O, Ge-N, Cr-N, Si-N, Al-N, Nb
Nitrides such as -N, Mo-N, Ti-N, Zr-N, Ta-N, Ge-ON, Cr-ON, Si-ON, A
1-ON, Nb-ON, Mo-ON, Ti-O-
Nitride oxide such as N, Zr-ON, Ta-ON, Ge-
C, Cr-C, Si-C, Al-C, Ti-C, Zr-
Carbides such as C and Ta-C, Si-F, Al-F, Ca-
A material that can achieve the above object, such as a fluoride such as F, another dielectric, or an appropriate combination thereof (for example, ZnS—SiO ₂ ) is used.

The interface layers 3 and 5 have a role of protecting the recording layer, such as preventing oxidation, corrosion, and deformation of the recording layer 4, and
It plays a role of improving the repetitive recording characteristics by preventing the diffusion of atoms constituting the recording layer 4 and the protective layer 2 and improving the erasing characteristics by promoting the crystallization of the recording layer 4. The position where the interface layers 3 and 5 are provided is the recording layer 4
Although only one of the interfaces may be used, it is more preferable to provide the interface on both sides of the recording layer 4 in order to exhibit the above-mentioned effects without regret. In particular, when the thickness of the recording layer 4 is relatively small, the recording layer is hardly crystallized. However, by providing the interface layers 3 and 5 on both sides, crystallization of the recording layer is promoted and high erasing performance can be obtained. It becomes possible.

The components contained in the interface layers 3 and 5 may diffuse into the recording layer 4 as information is repeatedly recorded. From this viewpoint, it is preferable to use a material that does not hinder the optical change of the recording layer 4 as a constituent material of the interface layers 3 and 5.

The material constituting the interface layers 3 and 5 may be any material that plays the role described above. Specifically, Ge-
N, Cr-N, Si-N, Al-N, Nb-N, Mo-
Nitride such as N, Ti-N, Zr-N, Ta-N, or Ge-ON, Cr-ON, Si-ON, Al-O
-N, Nb-ON, Mo-ON, Ti-ON, Z
Nitride oxide such as r-ON, Ta-ON, or Si-
O, Al-O, Ti-O, Ta-O, oxides such as Zr-O, or Ge-C, Cr-C, Si-C, Al-C,
Carbides such as Ti-C, Zr-C, Ta-C, or Si
Fluoride such as -F, Al-F, Ca-F, other dielectric materials, or an appropriate mixture of these materials can be used as a main component.

In particular, when a nitride or a nitride oxide is used as a main component, a dense film can be generally formed in many cases, and the above-mentioned effects are very remarkably obtained.

The thickness of the interface layers 3, 5 is preferably 1 nm or more. This is because, when the film thickness is less than 1 nm, the effect of preventing the above-described atom diffusion between the protective layer 2 and the recording layer 4 is reduced.

The recording layer 4 is made of a material whose optical characteristics change reversibly. In the case of a phase change recording medium, Te, S
It is preferable to use a chalcogenide-based material containing e as a main component. For example, Te-Sb-Ge, Te-Sb, Te
-Sb-In, Te-Sb-In-Ag, Te-Sb-
Sn-Ge, Te-Sb-Ge-Se, Te-Sn-S
b, Te-Bi-Sn-Ge, In-Sb-Se, In
A material mainly containing -Te-Se or the like can be used.

The recording layer 4 preferably contains N. This is because, when N is added to the recording layer 4, the thermal conductivity in the film surface of the recording layer 4 is reduced, and the adjacent erasure is less likely to occur. It is preferable that the amount of N added is 0.5 atomic mol% or more and 15 atomic mol% or less. 0.5 atom mol
% Or less, it is difficult to sufficiently obtain the effect of adding N. If the amount is 15 atomic mol% or more, the optical change of the recording material becomes small, which is disadvantageous in recording at higher density. It is because it becomes.

The thickness of the recording layer 4 is 1 nm or more and 15 nm
The following is preferred. This is because when the film thickness is less than 1 nm, the recording material does not easily form a layer,
In the case of m or more, thermal diffusion in the recording layer surface becomes large, so that adjacent erasure is likely to occur when recording is performed at high density.

The heat insulating layer 6 has the same role as the protective layer 2,
That is, in addition to the role of protecting the recording material and adjusting the optical characteristics to enable effective light absorption in the recording layer, it is necessary to prevent the heat generated in the light absorbing layer 7 from diffusing into the recording layer 4. It also plays the role of heat insulation to prevent it. This is to prevent the heat generated in the light absorbing layer 7 from diffusing into the recording layer 4 and erasing the written mark.

As a specific material for forming the heat insulating layer 6,
Is, for example, a sulfide such as ZnS or a selenide such as ZnSe
Material, Si-O, Al-O, Ti-O, Ta-O, Zr-
Oxides such as O, Ge-N, Cr-N, Si-N, Al-
N, Nb-N, Mo-N, Ti-N, Zr-N, Ta-
Nitride such as N, Ge-ON, Cr-ON, Si-O
-N, Al-ON, Nb-ON, Mo-ON, T
Nitrogen oxidation of i-ON, Zr-ON, Ta-ON, etc.
Material, Ge-C, Cr-C, Si-C, Al-C, Ti-
Carbides such as C, Zr-C, Ta-C, Si-F, Al-
Fluoride such as F, Ca-F, other dielectrics, or these
(For example, ZnS-SiO _TwoEtc.)
For example, a material that can achieve the above object is used.

It is particularly preferable that the heat insulating layer 6 contains Si and O. In this case, since the bond of Si—O is easily formed in the heat insulating layer 6, the thermal conductivity of the heat insulating layer 6 is reduced, and the effect of heat insulation can be further increased.

More preferably, the thickness of the heat insulating layer 6 is 50 nm or more. This makes it possible to obtain a greater heat insulating effect.

The reflection layer 8 is made of Au, Ag, Cu, Al, N
It is formed from a metal such as i, Cr, Ti, or an alloy of a metal appropriately selected. The reflection layer 8 is provided to obtain an optical effect such as a heat radiation effect and effective light absorption in the recording layer 4.
When the reflective layer 8 is provided, it is preferable that the thickness is 1 nm or more. If the thickness of the reflective layer 8 is less than 1 nm, it is difficult to form a uniform layer, and the thermal and optical effects are reduced.

Next, the light absorbing layer 7 which is a main part of the present invention will be described.
Will be described. The role of the light absorbing layer 7 will be described below. First, in the process of increasing the temperature at the time of writing a mark, heat is generated due to light absorption in the light absorbing layer 7, which can help generate heat near the recording layer 4. improves. Next, in the cooling process at the end of mark writing, the amount of heat generated in the light absorbing layer 7 is immediately cooled by the reflective layer 8 and does not adversely affect the recording layer 4.

As described above, the provision of the light absorbing layer 7 can help increase the temperature in the recording layer 4. This makes it possible to write a mark with a sufficient amplitude even with lower power. For this reason, it is possible to prevent the adjacent marks from being erased when writing marks, that is, so-called adjacent erasure is caused.

To achieve the above role, the light absorbing layer 7
The following three conditions are mainly required.
The first condition is that it has appropriate light absorption at the wavelength of the laser beam used for recording. This is an essential condition for enabling the above role. The second condition is that the thermal conductivity is within an appropriate range. This is because, in order to enable the above role, it is required that the heat conduction in the film surface of the light absorbing layer 7 be within a certain range. The third condition is that mechanical and chemical stability are sufficient. The light absorbing layer 7 generates heat due to light absorption. Even in such a case, the light absorbing layer 7 must be made of a material that does not cause a change such as breakage, deformation, crack, or oxidation.

In order to achieve the first condition, as the light absorbing layer 7, the complex refractive index n-ik at the wavelength of the laser beam for recording has a condition A: 0 <n <2.5 and 0 <
k ≦ 5 or condition B: 2.5 ≦ n ≦ 6.0 and 3.5
A material that satisfies any one of ≦ k ≦ 5.0 or condition C: 5 <k ≦ 8 is used. Here, the wavelength of the laser beam used for recording is in the range of 300 nm to 500 nm.

When the light-absorbing layer 7 satisfies the complex refractive index range, light absorption in the light-absorbing layer 7 can be caused while maintaining a large difference in the optical characteristics of the recording layer 4. This makes it possible to reduce adjacent erasure. The basis of this complex refractive index range will be specifically described below.

First, with respect to a medium having the same configuration as that of FIG. 1, only the optical constant of the light absorption layer 7 was changed, and the range in which the characteristics of the medium were obtained favorably was estimated by optical calculation.
Optical calculation determines the optical constant and film thickness of each layer in the multilayer film,
Formulas based on the law of conservation of light energy were derived at all interfaces in the multilayer film, and the simultaneous equations were solved to determine the reflectance, the transmittance, and the absorptivity of the light absorbing layer 7 in the entire multilayer film.

Here, the thickness of each layer constituting the medium is 10 nm for the recording layer 4, 20 nm for the light absorbing layer 7, and 80 nm for the reflecting layer 8.
The maximum value ΔRmax of the reflectance difference of the medium obtained when the thickness was fixed at nm and the thicknesses of the protective layer 2 and the heat insulating layer 6 were changed was calculated. The material forming each layer is such that the recording layer 4 is Ge ₂₉ Sb ₁₄
Te ₅₄ N ₂ , the protective layer 2 and the heat insulating layer 6 are both S
A material in which 20 mol% of iO ₂ is mixed, the reflection layer 8 is made of Al ₉₈
Cr ₂ was used. The complex refractive index n-ik of the light absorption layer 7 is n
Was changed from 1 to 6 and k was changed from 1 to 8, and in each case, ΔRmax was determined. △ Rmax is
The calculation was performed by focusing attention only on the case where the reflectance when the recording layer 4 was in the crystalline state was smaller than the reflectance when the recording layer 4 was in the amorphous state. FIG. 2 shows the result of this optical calculation.

According to FIG. 2, condition A: 0 <n <2.5 and 0 <k ≦ 5, or condition B: 2.5 ≦ n
In any case where ≦ 6.0 and 3.5 ≦ k ≦ 5.0 or when Condition C: 5 <k ≦ 8, ΔRmax may take a large value of 15% or more. Understand. Regarding the optimum range of the complex refractive index, similar results were obtained when the reflectance when the recording layer 4 was in the crystalline state was larger than the reflectance when the recording layer 4 was in the amorphous state. Further, Ge-Sb-
When a material having a different composition of Te is used, or when the reflective layer 8
The same result was obtained when another material was used as the material.

When the condition A is satisfied, since n is relatively small, excessive light absorption does not occur in the light absorbing layer 7, and a large difference in reflectivity of the medium and an appropriate light absorption in the light absorbing layer 7 are achieved. It can be easily compatible. For this reason, the effect of reducing adjacent erasure can be greatly increased. Specific materials satisfying the condition A include, for example, In—Sb, Sn—Te, Cr
-Te, Al-Sb, Pb-Te, Au, Ag, Cu,
Ni, Cr, Pt, Nb, Pd, Sn, Sb, Bi, I
n, Zn, or a material combining these materials, such as Ni-Cr, Au-Cr, or a material containing at least one of these materials. Alternatively, Si
C, SiO ₂ , TiO ₂ , a dielectric such as TiN, or another material such as a metal or a semiconductor is added to these dielectrics,
A material satisfying the condition A may be used. As a main component, a material having optically favorable characteristics as described above,
It is more preferable to use a material whose material composition and the like are adjusted so that the thermal conductivity falls within an appropriate range described later.

When condition B is satisfied, ΔRmax is slightly reduced as compared with the case where condition C is satisfied, but a large ΔRmax is obtained at which the signal amplitude can be sufficiently obtained. , A moderate light absorption can be obtained. For this reason, the effect of reducing adjacent erasure can be greatly increased. As a specific material that satisfies the condition B, for example, a Ge-containing material such as Ge-W, Ge-Mn, and Ge-Cr is exemplified. As for these materials, it is preferable to use those whose material composition and the like are adjusted so that the thermal conductivity falls within an appropriate range described later, similarly to the materials satisfying the condition A.

When the condition C is satisfied, there is an advantage that ΔRmax becomes very large. However, this is because the light absorption in the light absorbing layer 7 is slightly reduced as compared with the case where the conditions A and B are satisfied, and the effect of the adjacent erase reduction satisfies the conditions A and B. It is slightly smaller than in the case. For this reason, it is only necessary to give priority to increasing the signal amplitude, but also to reduce adjacent erasure characteristics at the same time. For example, as in the case where recording is performed only in the groove portion using a substrate in which the groove portion and the land portion are alternately formed, adjacent erasure is slightly unlikely to occur, but the recording condition in which the signal amplitude needs to be large is used. It is preferable to use a material that satisfies C. Specific materials satisfying the condition C include, for example, Al, Al-Cr, Al-W
And the like. Also in this case, it is preferable to use a material whose material composition and the like are adjusted so that the thermal conductivity falls within an appropriate range described later.

If none of the conditions A, B and C is satisfied, and 2.5 <n and 0 ≦ k <3.5, the light absorbing layer 7
The optical absorptance of the medium becomes very large, and the difference in optical characteristics as a medium becomes small. For this reason, even if adjacent erasure can be reduced, it is difficult to obtain a sufficiently large signal when performing high-density recording, which is disadvantageous in achieving high density.

The optical constant of the light absorbing layer 7 can be measured using a spectroscope or an ellipsometer. At this time, as the measurement sample, a material in which the material of the light absorption layer 7 is formed on an appropriate substrate such as Si or SiO _{2 by} a thickness capable of measuring the optical constant may be used. The material of the light absorbing layer 7 is identified by electron spectrochemical analysis (ESCA), Auger electron spectroscopy (A
UGE), secondary ion mass spectrometry (SIMS), or the like, and a measurement sample may be prepared so as to be a material equivalent thereto.

The light absorption of the recording laser light in the light absorbing layer 7 is preferably 5% or more and 40% or less.
This is because if it is smaller than 5%, the effect of reducing the adjacent erasure of the light absorbing layer 7 is reduced, and if it is larger than 40%, the optical characteristic difference of the medium is reduced as described above. is there. On the other hand, when it is larger than 40%, heat generation in the light absorbing layer 7 becomes extremely large, so that there is a disadvantage that mechanical and chemical changes such as destruction and oxidation of the light absorbing layer 7 easily occur.

As a result of examining various materials for the light absorbing layer 7, the thermal conductivity at 800K of the light absorbing layer 7 was 0.0
The present inventors have found that a particularly excellent adjacent erase reduction effect can be obtained when a material having a value of 1 W / (m · K) or more and 5.0 W / (m · K) or less is used. This is because, when the thermal conductivity of the light absorbing layer 7 is larger than 5.0 W / (m · K), the heat conduction in the film surface of the light absorbing layer 7 is large, so that the heat generation in the recording layer 4 is reduced. It is considered that it is difficult to help and the effect of improving sensitivity is reduced. If the thermal conductivity of the light absorbing layer 7 is smaller than 0.01 W / (m · K), the light absorbing layer 7 generates extremely local heat, which is likely to cause film destruction or the like, which is not preferable. . 8
The basis for considering the value at 00K is that the melting point of the recording layer 4 is generally 800K to 900K, and the temperature near the light absorbing layer 7 often rises to near 800K during signal recording. This is because the thermal conductivity of the material becomes a problem.

For the measurement of the thermal conductivity of the light absorbing layer 7,
First, the thermal diffusivity was measured by using the optical alternating current method, and the value obtained by multiplying this by the heat capacity was calculated as the thermal conductivity. What is the optical exchange method?
When a mask is placed on a sample and AC heat is irradiated from the upper surface of the mask, the thermal diffusivity is calculated by obtaining the AC temperature amplitude at a position sufficiently distant from the mask edge as a function of the position. Here, as a sample for measuring the thermal diffusivity, the material of the light absorbing layer 7 is formed in a strip shape (for example, 5 mm × 3 mm).
A sample formed on an appropriate substrate such as polyimide (about 0 mm) with an appropriate thickness (for example, about 0.3 μm) may be used. The material of the light absorbing layer 7 is identified by the ESC
A, AUGE, SIMS, or another analysis method may be used, and a measurement sample may be prepared so as to be a material equivalent thereto.

The light absorbing layer 7 is preferably in an amorphous state. At this time, it is possible to easily satisfy the above-mentioned favorable range of thermal conductivity.

The light absorption layer 7 is preferably made of a material containing at least one of nitrogen, oxygen and carbon. This is because, when such a material is used, the optimum thermal conductivity range of the light absorption layer 7 can be easily satisfied. At this time, the content is adjusted so that the optical constant of the light absorbing layer 7 satisfies any of the above-described conditions A, B, and C.

The thickness of the light absorbing layer 7 is 5 nm or more and 60 n
m or less. When the thickness is less than 5 nm, light absorption is reduced, and the role as a light absorption layer is reduced. On the other hand, when the thickness exceeds 60 nm, the light absorption in the light absorbing layer 7 tends to be excessively large. It is because it becomes.

The light absorption layer 7 is preferably provided in contact with the reflection layer 8. This is because, as described above, in order to achieve the effect of reducing the adjacent erasure according to the present invention, it is necessary to instantaneously cool the heat generated in the light absorption layer 7 at the time of cooling after the completion of signal recording. However, when the reflection layer 8 and the light absorption layer 7 are in contact with each other, this is possible more effectively.

Next, a method for manufacturing these optical information recording media will be described. As a method of producing the multilayer film constituting the optical information recording medium, a method such as a sputtering method, a vacuum deposition, and a chemical vapor deposition (CVD) can be used. Here, as an example, description is made using a sputtering method.
FIG. 3 shows a schematic diagram of an example of a film forming apparatus.

A vacuum pump (not shown) is connected to the vacuum vessel 9 through an exhaust port 15 so that the inside of the vacuum vessel can be maintained at a high vacuum. Gas supply port 14
Can supply a constant flow of a rare gas, nitrogen, oxygen, or a mixed gas thereof.
In the figure, reference numeral 10 denotes a substrate, which is attached to a driving device 11 for rotating the substrate 10 on its own axis. Reference numeral 12 denotes a sputter target, which is connected to the cathode 13. Cathode 13
Although not shown, is connected to a DC power supply or a high-frequency power supply through a switch. Also, by grounding the vacuum container 9, the vacuum container 9 and the substrate 10 are kept at the anode.

As a film forming gas, a rare gas or a gas obtained by mixing a small amount of nitrogen, oxygen, or the like with a rare gas as necessary is used. As the rare gas, a gas capable of forming a film, such as Ar or Kr, may be used.

When forming the recording layer 4, the protective layer 2, and the heat insulating layer 6, it is preferable to use a mixed gas of a rare gas and a trace amount of nitrogen or a trace amount of oxygen. In this case, the thermal conductivity of each layer is reduced, and the effect of reducing adjacent erasure can be more effectively obtained. In this case, since mass transfer during repeated recording on the medium can be suppressed, there is an advantage that the repeated recording characteristics are improved.

When a nitride, an oxide or a nitride oxide is used as a main component of the interface layers 3 and 5, a good quality film is often obtained by sputtering by a reactive sputtering method. For example, Ge-Cr is used as an interface layer.
When -N is used, a material containing at least Ge and Cr is used as a target, and a mixed gas of a rare gas and nitrogen is used as a deposition gas. Alternatively, a rare gas and N ₂ O, NO ₂ , NO,
A mixed gas of a gas containing a nitrogen atom such as N ₂ or a mixed gas of a rare gas and a gas composed of an appropriate combination of the above-described gas containing a nitrogen atom may be used.

When forming the light absorbing layer 7 and the reflecting layer 8, it is preferable to use a rare gas such as Ar or Kr as a film forming gas. Further, as a material of the light absorbing layer 7, nitrogen,
Alternatively, when oxygen or carbon is contained, a gas containing a nitrogen atom, a gas containing an oxygen atom,
A mixture of gases containing carbon atoms may be used.

The step of forming the reflection layer 8 is preferably provided immediately before or after the step of forming the light absorbing layer 7. According to this preferred example, as described above, adjacent erasure can be more effectively reduced.

Next, an example of a recording / reproducing method for the optical information recording medium formed as described above will be described. FIG.
FIG. 1 schematically shows an example of an apparatus used for recording and reproduction. For recording, reproducing and erasing signals, a laser light source 16, an optical head 18 having an objective lens 17 mounted thereon, a driving device 19 for guiding a laser beam irradiation position to a predetermined position, a track direction and a film surface A tracking control device and a focusing control device (not shown) for controlling the position in the vertical direction, a laser driving device (not shown) for modulating the laser power, and a rotation control device 20 for rotating the medium. Used. 21 is a medium (optical disk)
It is.

Recording and erasing of signals are performed by first rotating the medium 21 using the rotation control device 20, narrowing the laser beam to a minute spot by the optical system, and irradiating the medium with the laser beam. An amorphous state generation power level at which a local part of the recording layer can be reversibly changed to an amorphous state by laser irradiation is P1,
Similarly, the power of the crystal state generation power that can be reversibly changed to the crystal state by laser irradiation is set to P2, and the laser power is modulated between P1 and P2 to form a recording mark or an erased portion, thereby recording information. , Erase, and overwrite recording. Generally, a portion to be irradiated with the power of P1 is a so-called multi-pulse formed by a train of pulses.

The optical level of the recording mark is not affected by the laser irradiation at the power level lower than either of the power levels P1 and P2, and the irradiation of the recording mark from the medium is not affected by the irradiation. The power level at which sufficient reflectivity is obtained is set to the reproduction power level P3, and the signal from the medium obtained by irradiating the laser beam with the power of P3 is read by the detector.
The information signal is reproduced.

The wavelength of the laser beam used for signal recording is
The range is 300 nm to 500 nm. When the laser beam in the blue wavelength range is used, the minimum spot diameter can be made smaller, and recording at a higher density than before can be performed.

The laser wavelength for reproducing signals is not necessarily required to be the same as the laser wavelength for recording.
Lasers of different wavelengths may be used.

The amorphous generation power P1 is 10 mW
The following is preferred. This is because when using the optical information recording medium according to the present invention, the recording sensitivity is improved,
Although a sufficiently large signal amplitude can be obtained even with a low power of 10 mW or less, when recording is performed with such a low power, the influence of adjacent erasure is less likely to occur, and a higher density can be achieved. is there.

[0079]

[Embodiment 1] Next, a specific embodiment will be described.
The present invention will be described in further detail. As an example, in the configuration of FIG.
In this case, the substrate 1 has a thickness of 0.6 mm and a diameter of 120 mm.
Disc-like polycarbonate resin, protective layer 2 and heat insulating layer 6
Both are ZnS and SiO_Two20 mol% mixed material,
The interface layers 3 and 5 are both GeCrN, and the recording layer 4 is Ge₂₉S
b_FifteenTe ₅₄N_Two, The light absorption layer 7 is NiCr, and the reflection layer 8 is A
gPdCu alloy. The thickness of each layer is as follows.
00 nm, the interface layers 3 and 5 were both 5 nm, and the recording layer 4 was 1
0 nm, the heat insulation layer 6 is 54 nm, the light absorption layer 7 is 20 nm,
The reflective layer 8 was set to 80 nm.

Here, when forming the recording layer 4, a gas in which Ar is mixed with 2.5% by volume of nitrogen is applied at a total pressure of 0.13 Pg.
a, and DC 1.27 W / cm ²
Power was turned on. When forming the protective layer 2 and the heat insulating layer 6, a gas in which Ar is mixed with 1.0% by volume of oxygen is supplied so that the total pressure becomes 0.13 Pa, and a high-frequency power source is used as a cathode. The test was performed by applying a power of 10 W / cm ² . When forming the light absorption layer 7 and the reflection layer 8, Ar gas is supplied so as to have a total pressure of 0.26 Pa.
C 4.45 W / cm ² power was applied. When forming the interface layers 3 and 5, both target materials are Ge
Cr, a mixed gas of Ar and nitrogen as a sputtering gas, a sputtering gas pressure of 1.33 Pa, a nitrogen volume in the sputtering gas of 40%, and a sputtering power density of a high frequency of 6.37 W / cm.
As No. ² , a film was formed.

The medium manufactured by the above method is referred to as medium (1). For comparison, as shown in FIG. 5, a medium (0) has the same configuration as the medium (1) except that the light absorption layer 7 is not provided. Further, as another comparative example, a medium using Si as the light absorbing layer 7 was used as the medium (1).
00). Here, at a wavelength of 400 nm, the complex refractive index ni of NiCr forming the light absorbing layer 7 of the medium (1) is shown.
k was 1.8-i3.2, and the complex refractive index of Si forming the light absorption layer 7 of the medium (100) was 4.8-i0.2.

Next, the disk characteristics of these media were evaluated. The method is described below. First, a laser beam having a wavelength of 400 nm and a numerical aperture of an objective lens of 0.65 was used as a laser beam for recording / reproducing. The shortest mark length is
The substrate used was 0.26 μm, the disk rotation speed was 8.6 m / s, and the track pitch was a substrate in which grooves and lands were alternately formed every 0.34 μm.

The evaluation of the characteristics of the disk was carried out using the C / N ratio of the signal,
And overwrite erase characteristics and adjacent erase characteristics. The evaluation of the C / N ratio was performed by recording a mark (mark length 0.265 μm) having a length of 3T by an (8-16) modulation method with an appropriate laser power and measuring the C / N ratio. . The evaluation of the overwrite erasing characteristic is (8
-16) After recording a mark of 3T length in the modulation method with an appropriate laser power, overwrite a mark of 11T length with the same power and reduce the amplitude of the 3T mark at this time (hereinafter referred to as 3T erasure rate). ) Was measured.

In the evaluation of the adjacent erasure characteristic, first, a mark having a length of 3T is repeatedly recorded on a track having a groove at an appropriate power ten times, and then the signal amplitude is measured. Next, marks of 3T length and marks of 11T length are alternately recorded on the adjacent land tracks on both sides alternately 50 times, that is, 100 times in total, and then the laser power for erasing is scanned. Marks around the entire circumference have been deleted.
After this, again, 3T on the track in the middle groove part
The signal amplitude of the length mark was measured, and the decrease from the amplitude measured before writing the signal to the tracks on both sides was measured as the amount of occurrence of adjacent erasure.

Table 1 shows that the media (1),
The results of evaluating the medium (0) and the medium (100) are shown.

[0086]

[Table 1]

Here, regarding the C / N ratio, 場合 indicates that a C / N ratio of 50 dB or more was obtained, ○ indicates that the C / N ratio was less than 50 dB and was 48 dB or more, and X indicates that the C / N ratio was less than 48 dB. Regarding the overwrite erasing characteristic, the obtained 3T
The case where the erasing rate is 30 dB or more is indicated by ○, and the case where the erasing ratio is less than 30 dB is indicated by ×. Regarding the adjacent erasure characteristics, those where the amplitude reduction amount is 1 dB or less are indicated by ◎, those that are greater than 1 dB and 5 dB or less are indicated by ○, and those that are greater than 5 dB are indicated by x.

As is clear from Table 1, the medium (1) has a large C / N ratio, good overwrite erasing characteristics, and good adjacent erasing characteristics. On the other hand, in the medium (0), the C / N ratio and the overwrite erasing property are good, but the adjacent erasing property is greatly deteriorated. The medium (1) has better recording sensitivity than the medium (0) and requires a lower set laser power, so that adjacent erasure is less likely to occur. In the medium (100), the overwrite erasing characteristics and the adjacent erasing characteristics are good, but the C / N ratio is low. This is the light absorption layer 7
This is because the amount of light absorbed by the medium becomes too large, and the difference in the reflectance of the medium is reduced. In the medium (1), since the light absorbing layer 7 has an appropriate light absorption, it is possible to improve the adjacent erasing characteristic without lowering the C / N ratio.

As another embodiment of the present invention, the material of the light absorbing layer 7 is InSb, InSbN, PbTe, and Sb, respectively.
b, SiO ₂ —Au, Ge—Cr, Ge—W, Al—C
The mediums which were all the same as the medium (1) except that r and Al-W were used are referred to as mediums (2) to (10), respectively. Table 2
The results of the same evaluation as described above for the media (2) to (10) are shown below.

[0090]

[Table 2]

In Table 2, the complex refractive index n-ik at a wavelength of 400 nm of the material forming the light absorbing layer 7 of each medium is as follows:
In each case, condition A: 0 <n <2.5 and 0 <k ≦ 5, or condition B: 2.5 ≦ n ≦ 6.0 and 3.5 ≦ k ≦ 5.
0 or condition C: 5 <k ≦ 8 is satisfied. In Table 2, the optical constants of these materials are A, B, C
Which condition is satisfied is also described.

As is clear from Table 2, the media (2) to
As for the medium (1), it can be seen that the adjacent erasing characteristic is good for the medium (1) without lowering the C / N ratio. When the light absorbing layer 7 satisfies the conditions A and B, C /
Good characteristics are obtained for all of the N ratio, the overwrite erasing characteristics, and the adjacent erasing characteristics. When the condition C is satisfied, the adjacent erasing characteristics are slightly lowered. this is,
This is because the light absorption under the condition C in the light absorbing layer 7 is slightly lower than that under the conditions A and B.

Further, as a material of the light absorbing layer 7, SnT
e, AlSb, Cr-Te, Au-Cr, Ag-Cr,
Ag-Mg, Cu-Cr, Pt-Cr, Nb-Cr, P
d-W, Bi-Te, In-Te, Zn, Ge-W, G
Also in the case of using e-Mn, good adjacent erasing characteristics and a good C / N ratio almost similar to those of the medium (1) were obtained.

As described above, the wavelength of the recording laser beam is set to 3
The light absorption layer is provided from 00 nm to 500 nm, and its complex refractive index n-ik is set so that the condition A: 0 <n <2.5 and 0 <
k ≦ 5 or condition B: 2.5 ≦ n ≦ 6.0 and 3.5
By satisfying any one of ≦ k ≦ 5.0 or condition C: 5 <k ≦ 8, appropriate light absorption can be caused in the light absorbing layer, and adjacent erasure can be reduced. Was.

(Embodiment 2) Next, another embodiment of the present invention will be described. The protective layer 2 has the configuration shown in FIG.
The medium (11) is exactly the same as the medium (1) except that the thickness of the heat insulating layer 6 is 107 nm. In the medium (11), the light absorption layer 7 is made of Al-Cr,
And the same medium except that Al-W was used as the medium (12) and medium (13), respectively. Medium (11)
Table 3 shows the results of the same evaluation as in Example 1 for the medium (13).

[0096]

[Table 3]

As is clear from Table 3, good values were obtained for these three media, as in the case of the first embodiment, in all of the C / N ratio, the overwrite erase characteristic, and the adjacent erase characteristic. When the results of the medium (12) and the medium (13) are compared with the results of the medium (9) and the medium (10) in Example 1, respectively, the medium (12) and the medium (13) are adjacent to each other. Erasure characteristics are improved. this is,
In the medium (12) and the medium (13), since the heat insulating layer 6 has a relatively large thickness, the heat insulating effect can be more remarkably exerted at the time of cooling after irradiation of the recording laser, and the adjacent erasing property is improved. It is thought that there is.

(Embodiment 3) Next, the light absorbing layer 7 has the same structure as that of the medium (11), and is made of Au ₉₈ Cr ₂ or Au _{80.
Cr 20, Au 60 Cr 40,} Au 40 Cr 60, Au 20 Cr 80,
Au ₂ Cr ₉₈ , Cr, Cr ₈₃ O ₇ N ₁₀ , Cr ₆₅ O ₁₅ N ₂₀ ,
The media exactly the same as the media (11) except for using Cr ₄₅ O ₂₅ N ₃₀ are referred to as media (14) to medium (23), respectively. Table 4 shows the 800K materials of these light absorbing layers 7.
The results obtained by measuring the thermal conductivity in the above-mentioned method are also shown. In Table 4, in the column of thermal conductivity, a is 800
The value of the thermal conductivity at K is less than 0.01 W / (m · K), and the value of b is 0.01 W / (m · K) or more and 5.0 W / (m · K) or less. Yes, c is 5.
The case where it is larger than 0 W / (m · K) is shown. Table 4 shows the results of the same evaluation as in Example 1 for these media (14) to (23).

[0099]

[Table 4]

As is clear from Table 4, good characteristics were obtained for all the media, but the thermal conductivity of the light absorbing layer was 0.01 W / (m · K) or more and 5.0 W / (M
K) When the following condition b is satisfied, a better adjacent erase characteristic is obtained. This is because the above-described mechanism for reducing adjacent erasure by the light absorption layer 7 can be more remarkably obtained when the above thermal conductivity range is satisfied.

Example 4 Next, the same structure as the medium (11) was used, and the thickness of the light absorbing layer 7 was 2 nm, 3 nm, and 5 nm.
m, 10 nm, 20 nm, 50 nm, 60 nm, 80 n
Mediums (24) to (32) are the same as the medium (8) except that they were changed to m and 100 nm, respectively. Table 5 shows the results of the same evaluation as in Example 1 for these media.

[0102]

[Table 5]

As is clear from Table 5, good characteristics are obtained for all the media. However, when the thickness of the light absorbing layer 7 satisfies the condition of 5 nm or more and 60 nm or less,
A better adjacent erase characteristic and a better C / N ratio are obtained. This is because, when the thickness of the light absorbing layer 7 is smaller than 5 nm, the effect as the light absorbing layer is reduced, and the effect of improving the adjacent erasing characteristic is weakened. This is because the light absorption in the medium becomes very large, so that the difference in optical characteristics as a medium is reduced, and the C / N ratio is slightly reduced.

[0104]

As described above, the light absorption layer has at least the recording layer, the light absorption layer, and the reflection layer whose optical characteristics can be reversibly changed by the irradiation of the laser beam. When the rate n-ik is less than the condition A: 0 <n <2.5 and 0 <k
≦ 5, or condition B: 2.5 ≦ n ≦ 6.0 and 3.5 ≦
k ≦ 5.0 or Condition C: Any one of 5 <k ≦ 8 is satisfied, and the wavelength of the laser beam is 300 n
By setting the range from m to 500 nm, it is possible to provide an optical information recording medium capable of recording at higher density without erasing adjacent marks and a recording / reproducing method thereof.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of a layer configuration according to the present invention.

FIG. 2 is a diagram showing an optical constant range of a light absorbing layer in the present invention.

FIG. 3 is a schematic diagram illustrating an example of a film forming apparatus according to the present invention.

FIG. 4 is a schematic diagram showing an example of a recording / reproducing apparatus according to the present invention.

FIG. 5 is a schematic diagram showing an example of a conventional layer configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Protective layer 3 Interface layer 4 Recording layer 5 Interface layer 6 Heat insulation layer 7 Light absorption layer 8 Reflection layer 9 Vacuum container 10 Substrate 11 Substrate drive 12 Sputter target 13 Cathode 14 Gas supply port 15 Exhaust port 16 Laser light source 17 Objective Lens 18 Optical head 19 Drive device 20 Rotation control device 21 Medium 101 Substrate 102 Protective layer 103 Interface layer 104 Recording layer 105 Interface layer 106 Heat insulation layer 108 Reflection layer

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 7/004 G11B 7/26 531 7/26 531 B41M 5/26 X F term (reference) 2H111 EA04 EA23 EA32 FA01 FA11 FA12 FA14 FA17 FA21 FA24 FA25 FB05 FB06 FB09 FB10 FB12 FB16 FB17 FB19 FB21 FB23 FB24 FB25 GA01 5D029 JA01 JB35 MA02 MA04 MA28 5D090 AA01 BB05 BB17 CC01 CC04 DD01 DD05 EE02 FF11 KK03 A05A08 A121

Claims (18)

[Claims] 1. A complex refractive index of the light absorbing layer at a wavelength of the laser light, comprising at least a recording layer whose optical characteristics can be reversibly changed by irradiation with the laser light, a light absorbing layer, and a reflecting layer. When n-ik is the condition A: 0 <n <2.5
And 0 <k ≦ 5, Condition B: 2.5 ≦ n ≦ 6.0 and 3.
Optical information characterized by satisfying any condition selected from 5 ≦ k ≦ 5.0 and condition C: 5 <k ≦ 8, and the wavelength of the laser light is in a range of 300 nm to 500 nm. recoding media. 2. The optical information recording medium according to claim 1, wherein an interface layer is provided above and below the recording layer. 3. The thermal conductivity of the light absorbing layer at 800 K is 0.01 W / (m · K) or more and 5.0 W / (m · K).
K) The optical information recording medium according to claim 1, wherein 4. The optical information recording medium according to claim 1, wherein said light absorbing layer is in an amorphous state. 5. The light-absorbing layer is made of In-Sb, Sn-T.
e, Cr-Te, Al-Sb, Pb-Te, Au, A
g, Cu, Ni, Cr, Pt, Nb, Pd, Sn, S
The optical information recording medium according to claim 1, wherein the optical information recording medium is formed of a material including at least one selected from the group consisting of b, Bi, In, and Zn. 6. The optical information recording medium according to claim 1, wherein the light absorbing layer is formed from a material containing Ge. 7. The optical information recording medium according to claim 1, wherein the light absorbing layer is formed from a material containing at least one selected from nitrogen, oxygen, and carbon. 8. The light absorption layer has a thickness of 5 nm or more and 6
2. The optical information recording medium according to claim 1, which has a thickness of 0 nm or less. 9. The optical information recording medium according to claim 1, wherein at least one heat insulating layer is provided between the light absorbing layer and the recording layer. 10. The optical information recording medium according to claim 9, wherein the heat insulating layer is formed from a material containing at least Si and O. 11. The optical information recording medium according to claim 1, wherein the reflection layer is provided in contact with the light absorption layer. 12. The optical information recording medium according to claim 1, wherein the recording layer contains at least one selected from Ge, Sb, In, and Te. 13. The optical information recording medium according to claim 1, wherein the recording layer contains N. 14. The recording layer having a thickness of 1 nm or more,
2. The optical information recording medium according to claim 1, which has a thickness of 5 nm or less. 15. The laser according to claim 1, further comprising a step of forming a recording layer whose optical characteristics can be reversibly changed by irradiation with a laser beam, a step of forming a light absorbing layer, and a step of forming a reflective layer. When the complex refractive index n-ik of the light absorbing layer at the wavelength of light is the condition A: 0 <n <2.5 and 0
<K ≦ 5, condition B: 2.5 ≦ n ≦ 6.0 and 3.5 ≦ k
≦ 5.0 and condition C: 5 <k ≦ 8, and the wavelength of the laser light is 30
A method for producing an optical information recording medium, wherein the optical information recording medium is within a range of 0 nm to 500 nm. 16. The method for manufacturing an optical information recording medium according to claim 15, wherein the step of forming the reflection layer is provided immediately before or immediately after the step of forming the light absorbing layer. 17. A substrate having at least a recording layer capable of reversibly changing between an amorphous state and a crystalline state by irradiation with a laser beam, a light absorbing layer, and a reflecting layer, When the complex refractive index n-ik of the light absorbing layer at a wavelength is the condition A: 0 <n <2.5 and 0 <k ≦ 5,
Condition B: 2.5 ≦ n ≦ 6.0 and 3.5 ≦ k ≦ 5.0,
And condition C: a method for recording, reproducing, and erasing information using an optical information recording medium that satisfies one of the conditions selected from 5 <k ≦ 8. In this case, the power of the amorphous state generating power level at which a local part of the recording layer can be reversibly changed to the amorphous state by laser irradiation is set to P.
1. Similarly, the crystal state generation power level which can be reversibly changed to the crystal state by laser irradiation is P2,
1, lower than the power level of P2, the laser irradiation at the power level does not affect the optical state of the record mark, and the reflectivity is sufficient for reproducing the record mark from the medium by the irradiation. When the power level at which the power is obtained is set to the reproduction power level P3, information recording and erasing are performed by appropriately modulating the power of the laser light between the levels P1 and P2, and the laser light having the power of P3 is output. It is characterized in that the information recording is reproduced by irradiating, and the wavelength of the laser light at the time of irradiating the laser light of P1 and P2 level is 300n.
A recording / reproducing method for an optical information recording medium, wherein the distance is within a range from m to 500 nm. 18. The recording / reproducing method for an optical information recording medium according to claim 17, wherein said amorphous state generation power level P1 is 10 mW or less.