JPH09185846A - Information recording medium and information memory device - Google Patents

Abstract

(57) Abstract: It is possible to prevent the C / N (carrier-to-noise ratio) from lowering even in a large number of times of rewriting or super-resolution reproduction in an optical disc or the like. A diffusion preventing layer is provided between two reflecting layers,
Prevents the layer material from diffusing or reacting between the reflective layers.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording thin film, medium and device used for recording and reproducing digital information.

[0002]

2. Description of the Related Art Various principles of recording information on a thin film (recording film) by irradiating laser light are known. Among them, lasers such as phase transition (also called phase change) of film material and photodarkening are known. The one utilizing the change in atomic arrangement due to the irradiation of light has an advantage that an information recording medium having a double-sided disc structure can be obtained by directly laminating two disc members because the thin film is not deformed. Also, Ge-Sb-T
An e-type recording film has an advantage that information can be rewritten.

[0003] In the recording film of this type, sample servo system for performing high density, mark edge recording or the like 10 ⁴
When the rewriting is performed more than once, the recording film thickness changes due to the flow of the recording film, and the reproduced signal waveform is distorted. The flow of the recording film is caused by the laser irradiation during recording, and the recording film is gradually pushed by the deformation of the protective layer and the intermediate layer due to the thermal expansion. To prevent this, for example, Document 1
"The 41st Japan Society for Applied Physics Supporters Association Proceedings p996"
Discloses a method of preventing the flow of a recording film by using a Cr-Ge-Sb-Te system recording film. In addition, Reference 2 “Proceedings of 42nd Association of Applied Physics Supporters Association p”
No. 1033 "discloses a method of preventing the flow of the recording film by using two reflective layers of Si and Al alloy.

However, with this alone, C / N (carrier-to-noise ratio) can be obtained when rewriting is performed a number of times over 10 ^5.
May decrease. It is considered that this is because the layer material diffuses or reacts between the two reflective layers at the time of rewriting a large number of times to change the thermal conductivity and the optical constant, thereby lowering the C / N.

On the other hand, analog signals such as video and audio are converted to F
An M-modulated optical disc, an optical disc on which digital information such as electronic computer data, digital signals such as a facsimile signal and a digital audio signal is recorded due to unevenness, and an optical disc on which signals and data are recorded by a recording beam such as a laser beam and an electron beam. , In an optical disc having a thin film for recording information capable of recording signals and data in real time, the signal reproduction resolution is almost determined by the wavelength λ of the light source of the reproduction optical system and the numerical aperture NA of the objective lens. The mark period of 2NA / λ is the read limit.
To increase the density, there is a method of reproducing data recorded with unevenness using a medium whose reflectance changes due to a phase change.
From JP-A-292632, there is described in JP-A-5-73961 a medium having a fused mask layer for high density reproduction of data recorded on a phase change recording film. The structure of a medium capable of super-resolution reproduction such as these is almost the same as that of the medium for recording and reproduction except for the substrate, and when the super-resolution reproduction is performed many times, the flow of the super-resolution readout film Occurs and C /
It has the same problem that N drop occurs.

However, here, the phase change is not only the phase change between the crystal and the amorphous but also the mere melting (change to the liquid layer).
Shall be included.

[0007]

The above-mentioned prior art method has a problem that the C / N (carrier-to-noise ratio) decreases when rewriting or super-resolution reproduction is performed many times. It is considered that this is because the layer material diffuses or reacts between the two reflective layers to change the thermal conductivity and the optical constant.

An object of the present invention is to prevent a decrease in C / N even when rewriting or super-resolution reproduction is performed many times.

[0009]

[Means for Solving the Problems]

(1) formed on the substrate directly or via an underlayer,
An information recording thin film for recording and / or reproducing information by an atomic arrangement change caused by irradiation with an energy beam is provided as a recording layer or a mask layer for super-resolution reading, and a protective layer is provided, and a plurality of layers are provided. The information recording medium is characterized by including a reflection layer and a diffusion prevention layer on at least one of the interfaces between the reflection layers.

(2) In the information recording medium described in (1), the plurality of reflective layers are made of materials having different refractive indexes or extinction coefficients at the reading laser wavelength from each other. The information recording medium is characterized by comprising a reflection layer and a diffusion prevention layer between the reflection layer and the reflection layer.

(3) In the information recording medium described in (1), each of the above layers is laminated on a substrate in this order from a light incident side to a protective layer, a recording layer or a mask layer for super-resolution reading, and then. It is characterized in that it has a structure in which a first reflection layer, a diffusion prevention layer, and a second reflection layer are laminated in this order directly or via an intermediate layer.

(4) In the information recording medium described in (1), the diffusion preventing layer is W, Mo, Cr, Ti, V, M.
n, Fe, Co, Ni, Pd, Pt, Cu, Al-S
i, Al-Si-N, SiO 2, Si-N or them as a main component an alloy, a compound, characterized in that at least one composition close or to, the mixed material.

(5) In the information recording medium described in (1), the first reflection layer material is fluorinated, nitrided, oxidized, carbonized, sulphurized, or selenium after the final lamination step and / or the lamination of the first reflection layer. It is characterized by being formed by performing a halogenation treatment other than fluorination and fluorination.

(6) In the information recording medium described in (1), at least 1% is added to the atmosphere gas at the time of forming the first reflective layer after the final step of laminating the first reflective layer and / or after the lamination.
A diffusion preventing layer was formed by laminating the first reflection layer material using a mixed gas containing at least one of the above nitrogen, oxygen, chlorine, fluorine, hydrogen sulfide, carbon tetrachloride, hydrogen and iodine. It is characterized by

(7) In the information recording medium described in (1), at least 1% is added to the atmosphere gas at the time of forming the second reflective layer before and / or before the second reflective layer is laminated.
The diffusion preventing layer was formed by stacking the second reflective layer material using a mixed gas containing at least one of the above nitrogen, oxygen, chlorine, fluorine, hydrogen sulfide, carbon tetrachloride, hydrogen and iodine. It is characterized by

(8) In the information recording medium described in (1), the second reflective layer material is fluorinated, nitrided, oxidized, carbonized, sulfided before and / or before the second reflective layer is laminated. It is characterized in that it is formed by performing a halogenation treatment other than selenization and fluorination.

(9) In the information recording medium described in (1), in the process during which the diffusion prevention layer laminates the first reflection layer and the second reflection layer, reaction is prevented at the interface of at least one of the layers. It is characterized in that it is formed by performing at least one of the treatment and the diffusion prevention treatment.

(10) In the information recording medium described in (1), the first reflective layer is directly laminated on the recording film.

(11) In the information recording medium described in (1), the first reflective layer has a Si, Si--Ge mixed material, S.
At least one of i-N, Si-Sn, Si-Au, or Si-In mixed material, or a composition close to this, or the second reflective layer has Al-Ti, Al-A.
g, Al-Cu, Al-Cr, etc. containing Al alloy as a main component, Al, Cu, Cu alloy, Au, Au alloy, A
g, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W,
At least one of W alloy, Co, Co alloy, Pt, and Pt alloy, or a composition close to this is characteristic.

(12) In the information recording medium described in (1), the first reflective layer is Al-Ti, Al-Ag, Al.
-Based alloys such as -Cu and Al-Cr
Al, Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W, W alloy, C
At least one of O, Co alloy, Pt, and Pt alloy, or a composition close to this, or the second reflective layer is Si, Si-Ge mixed material, Si-N, Si-Sn, S.
At least one of i-Au and Si-In mixed material, or a composition close to this.

(13) The information recording medium described in (1) is characterized in that an intermediate layer is provided between the recording layer or the mask layer for super-resolution reading and the first reflective layer.

(14) In the information recording medium described in (1), the thickness of the protective layer is in the range of 70 nm or more and 130 nm or less.

(15) In the information recording medium described in (1), in the information recording medium, 95% or more of the total number of atoms of the recording layer or the mask layer for super-resolution reading has a phase change of L. When the component H is a high melting point component, it is represented by (L) _1-s (H) _s and satisfies 0.02 ≦ s ≦ 0.20.

(16) An optical head control circuit, a tracking error detecting means, an optical head movement, which is provided with a laser used for at least one of the recording, reproducing or super-resolution reproducing wavelength of the information recording medium described in (1). An information memory device comprising a driver, a recording data modulating means, a laser driver, a reproduction signal processing means, and a reproduction data sending means.

(17) As the material of the diffusion prevention layer, W, W
Alloys and compounds containing as the main component are preferable because they have a large effect of preventing diffusion and reaction. Next, Mo, Cr, Ti, V, Mn, F
e, Co, Ni, Pd, Pt, Cu, or alloys or compounds containing these as the main components are preferable because they have a large diffusion / reaction preventing effect.

In addition to the above, SiO ₂ , Si--N based materials,
Al-Si, Al-Si- N ( e.g., AlSiN _2),
Alternatively, a material having a composition close to that of the above materials may be used.

Further, B, C, Ag, Rh, Ir, O
s, Re, Ta, Hf, Ac, Y, Zr, Sc, Be,
Si, Sn, alloys or compounds containing these as main components may be used.

(ZnS) ₈₀ (SiO ₂ ) ₂₀ , ZnS of this
With a different mixing ratio of SiO and SiO, Si-O-N based material,
SiO, Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , Ce
O, La ₂ O ₃ , In ₂ O ₃ , GeO, GeO ₂ , PbO, S
nO, SnO ₂ , Bi ₂ O ₃ , TeO ₂ , WO ₂ , WO ₅ , S
oxides such as c ₂ O ₃ and ZrO, TaN, AlN, Si ₃
N ₄ -based material such as nitride, ZnS, Sb ₂ S ₃ , CdS,
_{In 2 S 3, Ga 2 S} 3, GeS, SnS 2, PbS, Bi 2
Sulfides such as S ₃ , SnSe ₂ , Sb ₂ Se ₃ , CdSe,
ZnSe, In ₂ Se ₃ , Ga ₂ Se ₃ , GeSe, GeS
e ₂ , SnSe ₂ , PbSe, Bi ₂ Se, and other selenides, CeF ₃ , MgF ₂ , CaF _2, and other fluorides, Si, Ge, TiB ₂ , B ₄ C, B, C, or the above materials You may use the thing of a composition close to. Further, it may be a layer of these mixed materials or a multilayer of these.

Further, the diffusion preventing layer 6 is made of W, Be, N.
i, Cu, Au, Pt, Ag, Zn, electrolytic iron, brass (C
If u ₇₀ Zn ₃₀ ), duralumin, stainless steel, fused silica, or a material having high strength is used, the flow of the recording film during recording is less likely to occur, which has the advantage of increasing the number of rewritable times.

The average thickness of the diffusion prevention layer 6 is 1 nm.
The above is preferred. 3n from the viewpoint of increasing the diffusion prevention effect
m or more, and more preferably 10 nm or less from the viewpoint of improving recording / reproducing characteristics.

(18) The diffusion prevention layer may be formed by reactive sputtering or sputtering by mixing a reactive gas with a sputtering gas by a magnetron sputtering device. In this case, the target for exclusive use of the diffusion prevention layer is not necessary, which is preferable.

Further, after the first reflective layer is formed, the interface portion of the first reflective layer is subjected to fluorination, nitriding, oxidation, carbonization, sulfurization, selenization, and halogenation treatment other than fluorination to form the first reflection layer. Good.

In addition, in the process of laminating the first reflective layer and the second reflective layer, the interface of at least one of the layers is formed by performing at least one of a reaction preventing treatment and a diffusion preventing treatment. May be.

The diffusion prevention layer 6 may be formed by continuously changing the composition in the process of forming the first reflection layer and the second reflection layer.

(19) Si, S as the material of the first reflective layer
Since the i-Ge mixed material can make the light absorptance of the recording mark portion smaller than the light absorptance of the portion other than the recording mark, the unerased portion due to the difference in the light absorptance can be prevented, and the rewritable number does not decrease. Ge content is 10 atomic% or more,
When it is 80 atomic% or less, the number of rewritable times does not easily decrease.

Then, Si-N, Si-Sn, Si-A
Similar results were obtained with u, a Si-In mixed material, or a mixed material of two or more kinds of these mixed materials. These reflective layer materials are not only the phase change film of the present invention,
Even when used as a reflective layer material when another phase change film is used, the number of rewritable times does not decrease as compared with the conventional reflective layer material. The content of elements added to Si is 3 atomic% or more,
When it is 50 atomic% or less, the number of rewritable times does not easily decrease.

Further, a layer made of a Si / Ge-containing mixed material other than the above, a material having a large refractive index and a small extinction coefficient may be used, or a multi-layer composed of these phases may be used. You may use the composite layer etc. with other substances, such as these oxides. Ge can also be used. In addition, various nitrides, sulfides, and selenides can also be used.

Further, a material having a refractive index n and an extinction coefficient k of n ≧ 2 at the reading wavelength is more preferable, and a material having n ≧ 2 and 2 ≧ k is particularly preferable.

Further, a multi-layer composed of those layers may be used, or a composite layer of these and another substance such as an oxide such as SiO 2 may be used. At this time, the difference in refractive index n between the first reflective layer and the second reflective layer is preferably 2 or more.

(20) The second reflective layer material is Al-
It is preferable that the main component is an Al alloy such as Ti, Al-Ag, Al-Cu, and Al-Cr. Al can also be used. Materials other than Al alloy can also be used.

In the case of an Al alloy, if the Al content is 50 atomic% or more and 99.9 atomic% or less, the thermal conductivity can be increased,
Rewriting is less likely to occur.

Further, Sb-Bi, Au, Ag, Cu, A
l, Ni, Fe, Co, Cr, Ti, Pd, Pt, W,
Ta, Mo, Sb, Bi, Dy, Cd, Mn, Mg, V
Element may be used, or an alloy containing them as a main component, or a layer made of an alloy of these elements may be used, or a multi-layer made of these layers may be used, or other elements such as oxides may be used. A composite layer with a substance or the like may be used. First
If the material has a different refractive index and extinction coefficient from the reflective layer,
An alloy containing Si, Ge, Sn, or In as a main component, or a layer formed of an alloy of these elements and the above elements may be used, or a multi-layer formed of these layers may be used, or an oxide of these layers may be used. You may use the composite layer etc. with other substances, such as.

Among them, those having a large thermal conductivity, such as Cu alloy and Al alloy, have a rapidly cooled disk structure, and the fluctuation of reflectance due to rewriting many times is unlikely to occur. Further, those having a small thermal conductivity such as Sb-Bi and Dy have an advantage that the recording sensitivity is improved because the temperature is easily kept.

The thickness of the second reflective layer may be 0 nm, but 5
nm or more is preferred. 30 nm from the point of increasing the strength
As described above, from the viewpoint of reducing the manufacturing time, it is more preferably 300 nm or less.

(21) As a combination of the first reflective layer and the second reflective layer, the first reflective layer is a Si, Si-Ge mixed material, Si-N, Si-Sn, Si-Au, or Si-.
At least one of In mixed materials, or a composition close to this, or the second reflective layer has Al-Ti, Al-Ag, Al
-Based alloys such as -Cu and Al-Cr
Al, Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W, W alloy, C
At least one of O, Co alloy, Pt, and Pt alloy, or a composition close to this is preferable because the number of rewritable times is large. (22) As a combination of the first reflective layer and the second reflective layer, the first reflective layer is made of a material having an extinction coefficient k of 4 or less, and the second reflective layer has an extinction coefficient of the first extinction coefficient. It is preferable to use a material that is larger than the reflective layer and has a thermal conductivity of 100 W / m · k or more, because the absorptivity can be appropriately maintained and the temperature of the recording film at the time of recording can be appropriately maintained.

(23) It is preferable to select the combination of the first reflective layer and the second reflective layer as follows, because it is easy to control the absorptance in the amorphous state and the crystalline state.

As the material of the first reflective layer, Mo, Ni, F
e, Cr, Ti, Pd, Pt, W, Ta, Co, Sb,
A single element of Bi, Dy, Cd, Mn, Mg, or V, an alloy containing them as a main component, or a layer formed of an alloy of these elements may be used, or a multi-layer formed of these layers may be used. Alternatively, a composite layer of these and another substance such as an oxide may be used. By using a material having an extinction coefficient of 4 or less, it is possible to reduce the difference in absorptance when the absorptance in the amorphous state is higher than that in the crystalline state,
The erasure remaining when rewriting was reduced.

Among these, Mo, W, Ta, Mo alloy, W
Alloys, Ta alloys, and the like have low reactivity, and there is no possibility that the characteristics will change due to reaction with the second reflective layer material due to a large number of laser irradiations.

Further, Cr ₄ Te ₅ , Cr-Te, Cr-S
b, Cr-Ge, Co-Sb, Co-Te, Co-G
e, Cu-Te, Cu-Sb, Mn-Te, Mn-S
b, V-Ge, Ni-Ge, Mo-Ge, at least one selected from the group consisting of a mixture of a mixture of W-Te and a mixture, or a material having a composition close to this may be used. These materials have a high melting point, and there is no fear that the characteristics will change due to reaction with the second reflective layer material, and thus there is an advantage that the rewriting characteristics are good.

As a combination of the first reflective layer and the second reflective layer, the first reflective layer is Al-Ti, Al-Ag, Al.
-Based alloys such as -Cu and Al-Cr
Al, Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W, W alloy, C
At least one of O, Co alloy, Pt, and Pt alloy, or a composition close to this, or the second reflective layer has Si, Si—Ge mixed material, Si—N, Si—Sn, S.
It is preferable to use at least one of i-Au and Si-In mixed materials, or a material having a composition close to that of the i-Au or Si-In mixed materials because the absorption rate can be appropriately maintained.

It is preferable to select the thickness of the first reflective layer in the range of 30 nm or less because the absorptance can be controlled. It is more preferable to select a film thickness that is even thinner, in the range of about 15 nm or less.

The second reflective layer includes Al, Cu, Au,
A material having a large thermal conductivity, such as a Cu alloy, an Al alloy, or an Au alloy, is preferable because the disk structure has a rapid cooling structure and reflectance fluctuations due to rewriting many times are less likely to occur. In this case, it is preferable that the thermal conductivity is 100 W / m · k or more because the number of times of rewriting increases, and 230 W / m
It is preferable that the number is m · k or more because the number of rewrites is doubled. Furthermore, compared to Au alone, Au-Ag, Au
Au alloys such as —Co and Au—Al are preferable because they have the advantage of increasing the adhesive strength.

In addition, if the material has an extinction coefficient larger than that of the first reflective layer, Ag, Ni, Fe, Cr, Ti, Pd,
Pt, W, Ta, Mo, Sb, Bi, Dy, Cd, M
Elemental elements of n, Mg, V, or alloys containing Ag alloys, Cu alloys, Al alloys, Pd alloys, Pt alloys, Ni alloys, Mn alloys, Sb-Bi compounds as their main components,
Alternatively, a layer made of an alloy of these materials may be used, a multi-layer made of these layers may be used, or a composite layer of these and another substance such as an oxide may be used. An alloy containing Si, Ge, Sn, In as a main component, or a layer formed of an alloy of these elements and the above elements may be used, or a multi-layer formed of these layers may be used.
A composite layer of these and another substance such as an oxide may be used.

The thickness of the second reflective layer may be 0 nm, but 5
nm or more is preferred. 30 nm from the point of increasing the strength
As described above, from the viewpoint of reducing the manufacturing time, it is more preferably 300 nm or less.

(24) As the material for the recording film and the material for the super-resolution readout layer, (Cr ₄ Te ₅ ) ₇ (Ge ₂ Sb ₂ Te ₅ ) ₉₃ ,
With different mixing ratios of Cr ₄ Te ₅ and Ge ₂ Sb ₂ Te ₅ ,
(Cr ₄ Te ₅ )-(GeSb ₄ Te ₇ ), (Cr ₄ Te ₅ )-(Ge
Materials such as Sb ₂ Te ₄ ), which have different composition ratios in the Cr—Ge—Sb—Te system, are less likely to reduce the number of rewritable times. Other composition ratio Cr-Ge-Sb-Te system may be used.

Then, Ag-Ge-Sb-Te, Co-
Similar results were obtained with Ge-Sb-Te, V-Ge-Sb-Te, and the like.

Further, Ge ₂ Sb ₂ Te ₅ , G other than the above
eSb ₂ Te ₄ , GeSb ₄ Te ₇ , In ₃ SbTe ₂ , I
n ₃₅ Sb ₃₂ Te ₃₃ , In ₃₁ Sb ₂₆ Te ₄₃ , GeTe, A
g-In-Sb-Te, Ni-Ge-Sb-Te, Pt
-Ge-Sb-Te, Si-Ge-Sb-Te, Au-
Ge-Sb-Te, Cu-Ge-Sb-Te, Mo-G
e-Sb-Te, Mn-Ge-Sb-Te, Fe-Ge
-Sb-Te, Ti-Ge-Sb-Te, Bi-Ge-
Even if it is replaced with at least one of Sb-Te and a composition close to these, or if part of Ge is replaced with In, characteristics close to this can be obtained.

A recording film obtained by adding a high melting point component to a Ge-Sb-Te system does not easily cause a decrease in the number of rewritable times. In the information recording medium, 95% of the total number of atoms in the recording layer
In the above composition, when L is a phase change component and H is a high melting point component, it is represented by (L) _1-s (H) _s , and 0.02 ≦ s ≦ 0.2
When 0 is satisfied, the recording and erasing characteristics are good and the number of rewritable times does not easily decrease, so that it is more preferable.

(25) Materials for the protective layer and the intermediate layer are (ZnS) ₈₀ (SiO ₂ ) ₂₀ , those in which the mixing ratio of ZnS and SiO ₂ is changed, Si--N type material, Si--O--N type material, S
iO ₂ , SiO, Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , Y
₂ O ₃ , CeO, La ₂ O ₃ , In ₂ O ₃ , GeO, GeO ₂ ,
PbO, SnO, SnO ₂ , Bi ₂ O ₃ , TeO ₂ , W
O ₂ , WO ₅ , Sc ₂ O ₃ , oxides such as ZrO, TaN,
_{AlN, Si 3 N 4, Al} -Si-N material (e.g., Al
SiN ₂ ) and other nitrides, ZnS, Sb ₂ S ₃ , CdS,
_{In 2 S 3, Ga 2 S} 3, GeS, SnS 2, PbS, Bi 2
Sulfides such as S ₃ , SnSe ₂ , Sb ₂ Se ₃ , CdS
e, ZnSe, In ₂ Se ₃ , Ga ₂ Se ₃ , GeS
e, GeSe ₂ , SnSe ₂ , PbSe, Bi ₂ Se, and other selenides, CeF ₃ , MgF ₂ , CaF _2, and other fluorides, or Si, Ge, TiB ₂ , B ₄ C, B, C, or the above A material having a composition similar to that of the above material may be used. Further, it may be a layer of these mixed materials or a multilayer of these.

The thickness of the intermediate layer is 60 nm or less, or 18
It is preferably 0 nm or more and 240 nm or less. In the case of 0 nm, that is, the intermediate layer can be omitted, and in this case, the number of layers is reduced by one, which facilitates the production of the information recording medium. In the range of 180 nm or more and 240 nm or less, there is an advantage that the recording sensitivity is improved, but the flow of the recording film is more likely to occur than when it is thin. In order to suppress the flow of the recording film, the thickness is preferably 60 nm or less. Also, 25
When the thickness is not more than nm, when the temperature of the recording film rises, heat is more likely to escape to the reflective layer side, which is advantageous because the flow of the recording film can be easily suppressed.

The thickness of the protective layer is 50 nm or more, 300 nm
The following is preferred. The range of 70 nm or more and 130 nm or less is more preferable because good read characteristics can be obtained when the read laser wavelength is shortened.

(26) As the substrate material, polycarbonate, polyolefin, epoxy, acrylic resin, chemically strengthened glass having an ultraviolet curable resin layer formed on its surface, or the like may be used. Further, not only the substrate of the continuous groove servo format but also the substrate of other formats such as the substrate having the irregularities of the sample servo format may be used. Substrate size is 13cm, 12cm, 3.5 inch, 2.5
Inches and other sizes may be used.

With regard to the constitution, two disc members may be manufactured by the same method, and the reflection layers 5 and 5'of the first and second disc members may be bonded to each other via the adhesive layer. Alternatively, instead of the second disk member, a disk member having another structure, a protective substrate, or the like may be used.

Further, in the super-resolution reproducing disk, a substrate on which information is directly recorded on the surface by unevenness is used, and besides, a chemically strengthened glass having a polyolefin, epoxy, acrylic resin, or ultraviolet curing resin layer formed on the surface is used. May be.

[0065]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments.

[Embodiment 1] (Structure / Manufacturing Method) FIG. 1 shows a sectional structure of an information recording medium in a first embodiment of the present invention. This medium was manufactured as follows.

First, a polycarbonate substrate 1 of a continuous groove format having a diameter of 13 cm and a thickness of 1.2 mm and having a groove and a groove of a tracking guide formed by continuous grooves on the surface was formed. Next, the substrate 1 was placed in a magnetron sputtering apparatus in order to sequentially form thin films on the substrate 1. This apparatus has a plurality of targets and is capable of sequentially forming a laminated film. In addition, the thickness and the reproducibility of the formed film are excellent. First on the substrate 1 (Zn
S) ₈₀ (SiO ₂ ) ₂₀ protective layer 2 consisting of a film with a thickness of about 110 n
m. Then, on the protective layer 2, (C
r ₄ Te ₅ ) ₇ (Ge ₂ Sb ₂ Te ₅ ) ₉₃
It was formed up to nm. Next, on the recording film 3, (ZnS)
_{After the} intermediate layer 4 made of ₈₀ (SiO ₂ ) ₂₀ film is formed to a film thickness of about 20 nm, the first reflective layer 5 made of a Si film is formed on the film in the same sputtering device to a film thickness of 88 nm and then W.
A diffusion prevention layer 6 made of a film was formed to a thickness of 7 nm, and a second reflection layer 7 made of an Al ₉₇ Ti ₃ film was formed to a thickness of 200 nm.
Thus, the first disc member was obtained.

A substrate 1'having a diameter of 13 cm and a thickness of 1.2 mm made of the same material as the first disk member and the substrate 1 is bonded to the second reflective layer 7 via an adhesive layer 8 and is shown in FIG. A disc-shaped information recording medium was obtained.

(Initial Crystallization) The recording films 3 and 3'of the medium thus manufactured were subjected to initial crystallization by using a high speed initial crystallizer manufactured by Hitachi Computer Instruments. Since the same applies to the recording film 3 ', only the recording film 3 will be described below.

Besides this, the initial crystallization can be performed by using the recording / reproducing apparatus shown in the block diagram of FIG. 6 without using the high-speed initial crystallization machine. The medium is rotated at a linear velocity of 7 m / s, the laser light power of the semiconductor laser (wavelength 680 nm) is maintained at a level (about 1 mW) at which recording is not performed, and the laser light has a numerical aperture (NA) of 0 in the recording head. The light was collected by a 0.55 lens and irradiated onto the recording film 3 through the substrate 1. The reflected light from the recording film 3 is detected to perform tracking so that the center of the laser light spot always coincides with the center of the tracking groove of the substrate 1, and the focus of the laser light is placed on the recording film 3. The recording head was driven while performing automatic focusing. Then, for the initial crystallization, the recording film 3
A continuous laser beam having a power of 14 mW was irradiated 10 times on each of the same recording tracks. Finally, continuous (DC) laser light with a power of 7 mW was irradiated 10 times. The irradiation time (light spot passage time) at each time is about 0.1 μsec.

As described above, when the laser beams having different powers are irradiated, the initial crystallization can be sufficiently performed.

Irradiation of these laser beams is performed by a semiconductor laser
If an array is used, or a light beam from a gas laser is divided into a plurality of beams, or a spot shape of a light beam from a high-power gas laser or a semiconductor laser is made into an ellipse elongated in the radial direction of the medium. , And more preferably. This makes it possible to complete the initial crystallization by rotating the medium a few times.

When a plurality of laser light spots are used, if the laser light spots are not arranged on the same recording track but the positions are gradually shifted in the radial direction of the medium, a wide range can be obtained by one irradiation. Can be initialized,
It has the effect of reducing the remaining loss.

(Recording / Erasing) Next, in the recording area of the recording film 3 in which the initial crystallization is completed as described above, the power of the laser light for recording is recorded while tracking and automatic focusing are performed in the same manner as described above. Was recorded between the intermediate power level (7 mW) and the high power level (14 mW). After passing the portion to be recorded, the laser light power is lowered to the low power level (1 mW) of the reproducing (reading) laser light. The amorphous point or a portion close to it which is formed in the recording area by the recording laser beam becomes the recording point.

The power ratio between the high level and the intermediate level of the recording laser beam is particularly preferably in the range of 1: 0.3 to 1: 0.8. In addition to this, another power level may be set for each short time.

In such a recording method, if new information is directly recorded in a portion where information has already been recorded, it can be rewritten with new information. That is, overwriting with a single circular light spot is possible.

However, the power (eg, 8 m) close to the intermediate power level (7 mW) of the power-modulated recording laser light is obtained by the first rotation or a plurality of rotations during rewriting.
The recorded information is once erased by irradiating the continuous light of W), and then the low power level (1 mW) of the reproducing (reading) laser light and the high power level of the recording laser light are obtained in the next one rotation. The recording may be performed by irradiating the laser light whose power is modulated according to the information signal between (14 mW) or between the intermediate power level (7 mW) and the high power level (14 mW) of the recording laser light. . In this way, if the information is erased and then recorded, the previously written information remains less and the high carrier-to-noise ratio (C / N) is obtained.

This method is effective not only for the recording film of the present invention but also for other recording films.

If the intermediate layer 4 is omitted in this disc, the number of times of rewriting is one digit less than that of the above, and the C
A decrease in / N occurred. However, the decrease in C / N was less than in the case where the intermediate layer 4 was omitted in the conventional structure disc. When the intermediate layer is omitted, the manufacturing process is reduced by one step, which is preferable in that the manufacturing time can be shortened.

(Effect of Diffusion Prevention Layer) FIG. 2 shows a sectional view of a conventional structure disk. In this disc, a first reflective layer 5 made of a Si film and a second reflective layer 7 made of an Al ₉₇ Ti ₃ film are directly laminated. Ordinary recording / erasing and super-resolution reproduction characteristics are as good as those of the disk shown in this embodiment of FIG.

However, recording and erasing were performed 10 ⁵ times under severe conditions in which the power of the laser light was increased by 15% from the optimum value.
When repeated more than once, in the disc of this embodiment,
As described above, it was possible to reduce the decrease in C / N as compared with the conventional structure disk.

[0082]

[Table 1]

In the conventional disc, the layer material is diffused between the first reflective layer 5 and the second reflective layer when rewriting many times,
Or it reacts and changes in thermal conductivity and optical constants occur, and C / N
It is considered that the decrease in the value was prevented by providing the diffusion prevention layer in the disk of this example.

(Diffusion Prevention Layer Material: High Melting Point Inorganic Compound, Alloy Material, etc.) As a material instead of W used for the diffusion prevention layer 6 in the present embodiment, an alloy containing W as a main component, a compound which diffuses and reacts. It has a large prevention effect and is preferable. Next, Mo, Cr,
Ti, V, Mn, Fe, Co, Ni, Pd, Pt, C
u, or alloys or compounds containing these as main components
It has a large reaction preventing effect and is preferable.

In addition to the above, SiO ₂ , Si--N based materials,
Al-Si, Al-Si- N ( e.g., AlSiN _2),
Alternatively, a material having a composition close to that of the above materials may be used.

Further, B, C, Ag, Rh, Ir, O
s, Re, Ta, Hf, Ac, Y, Zr, Sc, Be,
Si, Sn, alloys or compounds containing these as main components may be used.

(ZnS) ₈₀ (SiO ₂ ) ₂₀ , the mixture ratio of ZnS and SiO of which is changed, Si—O—N-based material, S
iO, Ta ₂ O ₅ , TiO ₂ , Al ₂ O ₃ , Y ₂ O ₃ , Ce
O, La ₂ O ₃ , In ₂ O ₃ , GeO, GeO ₂ , PbO,
SnO, SnO ₂ , Bi ₂ O ₃ , TeO ₂ , WO ₂ , WO ₅ ,
Oxides such as Sc ₂ O ₃ and ZrO, TaN, AlN, Si
Nitride such as ₃ N ₄ based material, ZnS, Sb ₂ S ₃ , CdS,
_{In 2 S 3, Ga 2 S} 3, GeS, SnS 2, PbS, Bi 2
Sulfides such as S ₃ , SnSe ₂ , Sb ₂ Se ₃ , CdSe,
ZnSe, In ₂ Se ₃ , Ga ₂ Se ₃ , GeSe, GeS
e ₂ , SnSe ₂ , PbSe, Bi ₂ Se, and other selenides, CeF ₃ , MgF ₂ , CaF _2, and other fluorides, Si, Ge, TiB ₂ , B ₄ C, B, C, or the above materials You may use the thing of a composition close to. Further, it may be a layer of these mixed materials or a multilayer of these.

The material of the diffusion preventing layer 6 is W, Be, N.
i, Cu, Au, Pt, Ag, Zn, electrolytic iron, brass (C
If u ₇₀ Zn ₃₀ ), duralumin, stainless steel, fused silica, or a material having high strength is used, the flow of the recording film during recording is less likely to occur, which has the advantage of increasing the number of rewritable times.

The average thickness of the diffusion prevention layer 6 is 1 nm.
The above is preferred. 3n from the viewpoint of increasing the diffusion prevention effect
m or more, and more preferably 10 nm or less from the viewpoint of improving recording / reproducing characteristics.

(Production Method of Diffusion Prevention Layer-2) The diffusion prevention layer 6 may be formed by another method other than the method using the sputtering target having the above diffusion prevention material composition.

The diffusion preventive layer 6 may be formed by reactive sputtering or sputtering by mixing a reactive gas into the sputtering gas with a magnetron sputtering device.
At least 1% or more of nitrogen, oxygen, chlorine, fluorine is added to the sputtering atmosphere gas containing Ar, Xe, etc.
A mixed gas containing at least one of hydrogen sulfide, carbon tetrachloride, hydrogen and iodine was used. In each case, a compound of the mixed gas was formed, such as a nitride when nitrogen was mixed and an oxide when oxygen was mixed. This manufacturing method requires controlling the gas component, but is preferable in that the target exclusively for the diffusion prevention layer is not required.

These diffusion preventing layers may be formed in the final step of laminating the first reflective layer and / or after the laminating, or in the first step of laminating the second reflective layer and / or before the laminating. Good. The diffusion prevention layer 6 may be formed by continuously changing the composition in the process of forming the first reflective layer and the second reflective layer.

(Manufacturing Method-3 of Diffusion Preventing Layer) Further, after forming the first reflecting layer, the interface of the first reflecting layer is treated with hydrofluoric acid, nitric acid,
Exposure to solutions of hydrogen peroxide, carbonic acid, sulfuric acid, hydrochloric acid, etc., or vapors of these solutions, and hydrogen selenide may cause fluorination, nitriding, oxidation, carbonization, sulfurization, halogenation other than fluorination,
It may be formed by performing selenization treatment.

(Manufacturing Method of Diffusion Prevention Layer-4) In the process of laminating the first reflection layer and the second reflection layer, the interface of at least one of the layers is subjected to at least one of reaction prevention treatment and diffusion prevention treatment. You may form by performing the above process.

(Process for Producing Diffusion Prevention Layer-5) After the final step of laminating the first reflecting layer and / or after laminating, the first reflecting layer and the fluoride, nitride, oxide, carbide, sulfide, selenide, fluorine The diffusion prevention layer may be formed by forming a film by simultaneous sputtering of two targets using one or more targets of halides other than halides, carbon, sulfur and selenium as raw materials. The first reflection layer and / or the second reflection layer and the fluoride, nitride, oxide, carbide, sulfide, selenide, halide other than fluoride, carbon, sulfur, and selenium before and / or before the lamination of the second reflection layer. The diffusion prevention layer may be formed by forming a film by co-sputtering two targets using one or more of the above targets as raw materials.

(First Reflective Layer Material) Instead of Si used for the first reflective layer 5 in this example, a Si—Ge mixed material as the material of the first reflective layer records the light absorptance of the recording mark portion. Since it can be made smaller than the light absorption rate of the part other than the mark,
It is possible to prevent the unerased portion due to the difference in light absorptance, and the number of rewritable times does not decrease. When the content of Ge is 10 atomic% or more and 80 atomic% or less, the rewritable number is less likely to decrease.

Then, Si-N, Si-Sn, Si-A
Similar results were obtained with u, a Si-In mixed material, or a mixed material of two or more kinds of these mixed materials. These reflective layer materials are not only the phase change film of the present invention,
Even when used as a reflective layer material when another phase change film is used, the number of rewritable times does not decrease as compared with the conventional reflective layer material. The content of elements added to Si is 3 atomic% or more,
When it is 50 atomic% or less, the number of rewritable times does not easily decrease.

Furthermore, a layer made of a mixed material containing Si and Ge other than the above, a material having a large refractive index and a small extinction coefficient may be used, or a multi-layer composed of these phases may be used. You may use the composite layer etc. with other substances, such as these oxides. Ge can also be used. In addition, various nitrides, sulfides, and selenides can also be used.

Further, a material in which the refractive index n and the extinction coefficient k of the first reflective layer material at the reading wavelength are n ≧ 2 is more preferable, and a material in which n ≧ 2 and 2 ≧ k is particularly preferable.

Further, a multi-layer composed of these layers may be used, or a composite layer of these and another substance such as an oxide such as SiO 2 may be used. At this time, the difference in refractive index n between the first reflective layer and the second reflective layer is preferably 2 or more.

(Second Reflective Layer Material) As a material for the second reflective layer instead of Al-Ti used for the second reflective layer 6 in this embodiment, Al-Ti, Al-Ag, Al-Cu, Al is used. -C
Those having an Al alloy as a main component such as r are preferable. Al can also be used. Materials other than Al alloy can also be used.

In the case of an Al alloy, if the Al content is 50 atomic% or more and 99.9 atomic% or less, the thermal conductivity can be increased,
Rewriting is less likely to occur.

Further, Sb-Bi, Au, Ag, Cu, A
l, Ni, Fe, Co, Cr, Ti, Pd, Pt, W,
Ta, Mo, Sb, Bi, Dy, Cd, Mn, Mg, V
Element may be used, or an alloy containing them as a main component, or a layer made of an alloy of these elements may be used, or a multi-layer made of these layers may be used, or other elements such as oxides may be used. A composite layer with a substance or the like may be used. First
If the material has a different refractive index and extinction coefficient from the reflective layer,
An alloy containing Si, Ge, Sn, or In as a main component, or a layer formed of an alloy of these elements and the above elements may be used, or a multi-layer formed of these layers may be used, or an oxide of these layers may be used. You may use the composite layer etc. with other substances, such as.

Among them, those having a large thermal conductivity, such as Cu alloy and Al alloy, have a rapidly cooled disk structure, and the reflectance is hardly changed by rewriting many times. Further, those having a small thermal conductivity such as Sb-Bi and Dy have an advantage that the recording sensitivity is improved because the temperature is easily kept.

The thickness of the second reflective layer may be 0 nm, but 5
nm or more is preferred. 30 nm from the point of increasing the strength
As described above, from the viewpoint of reducing the manufacturing time, it is more preferably 300 nm or less.

(Combination of First Reflective Layer and Second Reflective Layer-
1) As a combination of the first reflective layer and the second reflective layer, the first reflective layer may be Si, Si-Ge mixed material, Si-N, Si.
-Sn, Si-Au, or at least one of Si-In mixed materials, or a composition close to this, or the second reflective layer is Al-Ti, Al-Ag, Al-Cu, Al-Cr.
Al-based alloys such as Al, Cu, Cu alloys, Au, Au alloys, Ag, Ag alloys, Mo, Mo alloys, Ta, Ta alloys, W, W alloys, Co, Co alloys, P
At least one of t and Pt alloys or a composition close to this is preferable because the number of rewritable times is large. As described above, the materials described in the present embodiment can be used as the first reflective layer material and the second reflective layer material, but it has been found that the rewriting characteristics are improved by selecting a combination thereof.

(Combination of First Reflective Layer and Second Reflective Layer-
2) As a combination of the first reflective layer and the second reflective layer, the first reflective layer is made of a material having an extinction coefficient k of 4 or less,
Moreover, when the second reflective layer is made of a material having an extinction coefficient larger than that of the first reflective layer and a thermal conductivity of 100 W / m · k or more, the absorptivity can be appropriately maintained, and recording at the time of recording can be performed. It is preferable because the temperature of the film can be appropriately maintained.

(Combination of First Reflective Layer and Second Reflective Layer-
3) It is preferable to select the combination of the first reflective layer and the second reflective layer as follows, because it is easy to control the absorptance in the amorphous state and the crystalline state.

As the material of the first reflective layer, Mo, Ni, F
e, Cr, Ti, Pd, Pt, W, Ta, Co, Sb,
A single layer of Bi, Dy, Cd, Mn, Mg and V, an alloy containing these as the main components, or a layer formed of an alloy of these may be used, or a multi-layer formed of these layers may be used. Alternatively, a composite layer of these and another substance such as an oxide may be used. By using a material having an extinction coefficient of 4 or less, it is possible to reduce the difference in absorptance when the absorptance in the amorphous state is higher than that in the crystalline state.
The erasure remaining when rewriting was reduced.

Among these, Mo, W, Ta, Mo alloy, W
Alloys, Ta alloys, and the like have low reactivity, and there is no possibility that the characteristics will change due to reaction with the second reflective layer material due to a large number of laser irradiations.

Further, Cr ₄ Te ₅ , Cr-Te, Cr-S
b, Cr-Ge, Co-Sb, Co-Te, Co-G
e, Cu-Te, Cu-Sb, Mn-Te, Mn-S
b, V-Ge, Ni-Ge, Mo-Ge, at least one selected from the group consisting of a mixture of a mixture of W-Te and a mixture, or a material having a composition close to this may be used. These materials have a high melting point, and there is no fear that the characteristics will change due to reaction with the second reflective layer material, and thus there is an advantage that the rewriting characteristics are good.

As a combination of the first reflective layer and the second reflective layer, the first reflective layer is Al-Ti, Al-Ag, Al.
-Based alloys such as -Cu and Al-Cr
Al, Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W, W alloy, C
At least one of O, Co alloy, Pt, and Pt alloy, or a composition close to this, or the second reflective layer is Si, Si—Ge mixed material, Si—N, Si—Sn, S.
It is preferable to use at least one of i-Au and Si-In mixed materials, or a material having a composition close to that of the i-Au or Si-In mixed materials because the absorption rate can be appropriately maintained.

It is preferable to select the thickness of the first reflective layer in the range of 30 nm or less because the absorptance can be controlled. It is more preferable to select a film thickness that is even thinner, in the range of about 15 nm or less.

As the second reflective layer, Al, Cu, Au,
A material having a large thermal conductivity, such as a Cu alloy, an Al alloy, or an Au alloy, is preferable because the disk structure has a rapid cooling structure and reflectance fluctuations due to rewriting many times are less likely to occur. In this case, it is preferable that the thermal conductivity is 100 W / m · k or more because the number of times of rewriting increases, and 230 W / m
It is preferable that the number is m · k or more because the number of rewritings is doubled. Furthermore, compared with Au alone, Au-Ag, Au-
Au alloys such as Co and Au—Al are preferable because they have the advantage of increasing the adhesive strength.

In addition, if the material has a larger extinction coefficient than the first reflection layer, Ag, Ni, Fe, Cr, Ti, Pd,
Pt, W, Ta, Mo, Sb, Bi, Dy, Cd, M
n, Mg, V element simple substance, or an alloy containing these as the main components such as Ag alloy, Cu alloy, Al alloy, Pd alloy, Pt alloy, Ni alloy, Mn alloy, and Sb-Bi compound.
Alternatively, a layer made of an alloy of these materials may be used, a multi-layer made of these layers may be used, or a composite layer of these and another substance such as an oxide may be used. An alloy containing Si, Ge, Sn, In as a main component, or a layer formed of an alloy of these elements and the above elements may be used, or a multi-layer formed of these layers may be used.
A composite layer of these and another substance such as an oxide may be used.

The thickness of the second reflective layer may be 0 nm, but 5
nm or more is preferred. 30 nm from the point of increasing the strength
As described above, from the viewpoint of reducing the manufacturing time, it is more preferably 300 nm or less.

(Material of Recording Film) In this embodiment, the recording film 3 is used.
Is formed of (Cr ₄ Te ₅ ) ₇ (Ge ₂ Sb ₂ Te ₅ ) ₉₃ , but instead of this, the mixture ratio of Cr ₄ Te ₅ and Ge ₂ Sb ₂ Te ₅ is changed, (Cr ₄ Te ₅ )-(GeSb ₄ T
e ₇ ), (Cr ₄ Te ₅ )-(GeSb ₂ Te ₄ ), etc. Cr-
The Ge-Sb-Te-based materials having different composition ratios are unlikely to cause a decrease in the number of rewritable times. Other composition ratio Cr-G
An e-Sb-Te system may be used.

Then, Ag-Ge-Sb-Te, Co-
Similar results were obtained with Ge-Sb-Te and V-Ge-Sb-Te.

Further, Ge ₂ Sb ₂ Te ₅ , G other than the above
eSb ₂ Te ₄ , GeSb ₄ Te ₇ , In ₃ SbTe ₂ , I
n ₃₅ Sb ₃₂ Te ₃₃ , In ₃₁ Sb ₂₆ Te ₄₃ , GeTe, A
g-In-Sb-Te, Ni-Ge-Sb-Te, Pt
-Ge-Sb-Te, Si-Ge-Sb-Te, Au-
Ge-Sb-Te, Cu-Ge-Sb-Te, Mo-G
e-Sb-Te, Mn-Ge-Sb-Te, Fe-Ge
-Sb-Te, Ti-Ge-Sb-Te, Bi-Ge-
Even if it is replaced with at least one of Sb-Te and a composition close to these, or if part of Ge is replaced with In, characteristics close to this can be obtained.

A recording film obtained by adding a high melting point component to a Ge-Sb-Te system does not easily cause a decrease in the number of rewritable times. In the information recording medium, 95% of the total number of atoms in the recording layer
When the above composition is represented by (L) _1-s (H) _s , where L is a phase change component and H is a high melting point component, and 0.02 ≦ s ≦ 0.20 is satisfied, the recording / erasing characteristics are Is preferable and the number of rewritable times does not easily decrease, which is more preferable.

(Protective Layer and Intermediate Layer Material) In this embodiment, the protective layer 2 and the intermediate layer 4 are formed of (ZnS) ₈₀ (SiO ₂ ) _20. Instead of this, ZnS and SiO ₂ that changing the mixing ratio, Si-N-based material, SiO-N based _{material, SiO 2, SiO, Ta 2} O 5, TiO 2, Al 2 O 3,
_{Y 2 O 3, CeO, La} 2 O 3, In 2 O 3, GeO, GeO
₂ , PbO, SnO, SnO ₂ , Bi ₂ O ₃ , TeO ₂ , W
O ₂ , WO ₅ , Sc ₂ O ₃ , oxides such as ZrO, TaN,
_{AlN, Si 3 N 4, Al} -Si-N material (e.g., Al
SiN ₂ ) and other nitrides, ZnS, Sb ₂ S ₃ , CdS,
_{In 2 S 3, Ga 2 S} 3, GeS, SnS 2, PbS, Bi 2
Sulfides such as S ₃ , SnSe ₂ , Sb ₂ Se ₃ , CdSe,
ZnSe, In ₂ Se ₃ , Ga ₂ Se ₃ , GeSe, GeS
e ₂ , SnSe ₂ , PbSe, Bi ₂ Se and other selenides, CeF ₃ , MgF ₂ , CaF ₂ fluorides, Si, Ge, TiB ₂ , B ₄ C, B, C, or the above materials You may use the thing of a similar composition. Further, it may be a layer of these mixed materials or a multilayer of these.

The thickness of the intermediate layer is 60 nm or less, or 18
It is preferably 0 nm or more and 240 nm or less. In the case of 0 nm, that is, the intermediate layer can be omitted, and in this case, the number of layers is reduced by one, which facilitates the production of the information recording medium. In the range of 180 nm or more and 240 nm or less, there is an advantage that the recording sensitivity is improved, but the flow of the recording film is more likely to occur than when it is thin. In order to suppress the flow of the recording film, the thickness is preferably 60 nm or less. Also, 25
When the thickness is not more than nm, when the temperature of the recording film rises, heat is more likely to escape to the reflective layer side, which is advantageous because the flow of the recording film can be easily suppressed.

The thickness of the protective layer is 50 nm or more, 300 nm
The following is preferred. The range of 70 nm or more and 130 nm or less is more preferable because good read characteristics can be obtained when the read laser wavelength is shortened.

(Substrate Material, Structure, etc.) In this embodiment, the substrate 1 of the continuous groove servo format having the unevenness of the tracking guide by the continuous groove is directly used on the surface.
Instead, polyolefin, epoxy, acrylic resin, chemically strengthened glass having an ultraviolet curable resin layer formed on its surface, or the like may be used. Further, not only the substrate of the continuous groove servo format, but also the substrate of other formats such as a polycarbonate substrate on which unevenness of the sample servo format is formed may be used. Substrate size other than 13 cm, 1
2 cm, 3.5 inches, 2.5 inches and other sizes may be used.

In this example, two disc members were prepared by the same method, and the two disc members were bonded via an adhesive layer.
Although the reflection layers 5 and 5'of the first and second disk members are bonded to each other, a disk member having another structure or a protective substrate may be used instead of the second disk member. .

[Second Embodiment] (Structure / Manufacturing Method) FIG. 3 shows a sectional structure of an information recording medium according to a second embodiment of the present invention. This medium was manufactured as follows.

First, a polycarbonate substrate 9 having a diameter of 13 cm and a thickness of 1.2 mm and having information recorded on the surface by unevenness was formed. Next, in order to sequentially form thin films on this substrate,
The substrate 9 was placed in the magnetron sputtering apparatus. This apparatus has a plurality of targets and is capable of sequentially forming a laminated film. In addition, the thickness and the reproducibility of the formed film are excellent. First, the protective layer 2 made of a (ZnS) ₈₀ (SiO ₂ ) ₂₀ film was formed on the substrate 9 so as to have a film thickness of about 110 nm. Then, the protective layer 2
A (Cr ₄ Te ₅ ) ₇ (Ge ₂ Sb ₂ Te ₅ ) ₉₃ super-resolution readout layer 10 was formed thereon to a film thickness of about 35 nm. Next, an intermediate layer 4 made of a (ZnS) ₈₀ (SiO ₂ ) ₂₀ film is formed on the super-resolution readout layer 10 to a film thickness of about 20 nm, and then an Si film is made on the same in the same sputtering apparatus. The first reflection layer 5 has a thickness of 88 nm, the diffusion prevention layer 6 made of a W film has a thickness of 7 nm, and the second reflection layer 7 made of an Al ₉₇ Ti ₃ film has a thickness of 7 nm.
To a film thickness of 200 nm. Thus, the first disc member was obtained.

A substrate 1'having a diameter of 13 cm and a thickness of 1.2 mm, which is made of the same material as the first disk member and the substrate 9, is attached to the second reflective layers 7 and 7 'via an adhesive layer 8, The disc-shaped information recording medium shown in FIG. 3 was obtained.

(Initial Crystallization) The super-resolution reading layers 10 and 10 'of the medium manufactured as described above were subjected to initial crystallization by using a high-speed initial crystallizer manufactured by Hitachi Computer Instruments. Since the same applies to the super-resolution readout layer 10 ', the super-resolution readout layer 10 will be described below.
Will be described only.

Besides, the initial crystallization can be performed by using the recording / reproducing apparatus without using the high-speed initial crystallization machine. The medium is rotated at a linear velocity of 7 m / s, the laser light power of the semiconductor laser (wavelength 680 nm) is maintained at a level (about 1 mW) at which recording is not performed, and the laser light has a numerical aperture (NA) of 0 in the recording head. The light was condensed by a 0.55 lens, and the super-resolution readout layer 10 was irradiated through the substrate 9. The reflected light from the super-resolution reading layer 10 is detected, and tracking is performed so that the center of the laser light spot always coincides with the center of the tracking groove of the substrate 9, and the laser light on the super-resolution reading layer 10 is detected. The super-resolution reproducing head was driven while performing the automatic focusing so that the focal point could be reached. The super-resolution reproducing head is the same as the recording head shown in the first embodiment. And
For initial crystallization, continuous laser light with a power of 14 mW was irradiated 10 times on the same recording track of the super-resolution readout layer 10. Finally, continuous power of 7mW (DC)
Irradiation with laser light was performed 10 times. The irradiation time (light spot passage time) at each time is about 0.1 μsec.

As described above, when the laser beams having different powers are irradiated, the initial crystallization can be sufficiently performed.

Irradiation of these laser beams is performed by a semiconductor laser
If an array is used, or a light beam from a gas laser is divided into a plurality of beams, or a spot shape of a light beam from a high-power gas laser or a semiconductor laser is made into an ellipse elongated in the radial direction of the medium. , And more preferably. This makes it possible to complete the initial crystallization by rotating the medium a few times.

When a plurality of laser light spots are used, if the laser light spots are not arranged on the same recording track but the positions are gradually shifted in the radial direction of the medium, a wide range can be obtained by one irradiation. Can be initialized,
It has the effect of reducing the remaining loss.

(Super-Resolution Reproduction) Next, in the recording area of the super-resolution readout layer 10 in which the initial crystallization is completed as described above, the super-resolution is performed while tracking and automatic focusing are performed in the same manner as described above. The information reproducing laser light was irradiated at a high power level (12 mW) to perform super-resolution reproduction of information. After passing the portion where information is recorded, the laser light power is lowered to the low power level (1 mW) of the tracking laser light. After super-resolution reproduction, the recording region is amorphous or crystalline or a portion close to them. In the case of an amorphous state or a state close to that, initial crystallization is performed before the next super-resolution reproduction. This initial crystallization does not necessarily have to be performed by a high-speed initial crystallizer, and laser light may be irradiated with an intermediate power level (6 mW).

The power ratio between the high level and the intermediate level is particularly preferably in the range of 1: 0.3 to 1: 0.8. Also,
In addition to this, other power levels may be set for each short time.

Incidentally, when the intermediate layer 4 was omitted in this disc, the C / N was reduced by rewriting by an order of magnitude less than that in the case where the intermediate layer was not omitted. However, the decrease in C / N was less than in the case where the intermediate layer 4 was omitted in the conventional structure disc. When the intermediate layer is omitted, the number of manufacturing processes is reduced by one step, which is preferable in that the manufacturing time can be shortened.

(Effect of Diffusion Prevention Layer) FIG. 4 shows a sectional view of a conventional structure disk. In this disc, a first reflective layer 5 made of a Si film and a second reflective layer 7 made of an Al ₉₇ Ti ₃ film are directly laminated. Figure 3 shows the normal super-resolution reproduction characteristics.
It is as good as the disk shown in this example.

However, the super-resolution reproduction is performed by 10 ^{4 under} severe conditions in which the power of the laser light is increased by 15% from the optimum value.
When repeated more than once, in the disc of this embodiment,
As described above, it was possible to reduce the decrease in C / N as compared with the conventional structure disk.

[0139]

[Table 2]

In the conventional disc, the layer material diffuses or reacts between the first reflective layer 5 and the second reflective layer during a number of times of super-resolution reproduction, and thermal conductivity and optical constants change. C
It is considered that the decrease in / N could be prevented by providing the diffusion prevention layer in the disk of this example.

(Material for Super-Resolution Reading Layer) The same as the recording film material described in Example 1.

(Substrate Material, Structure, etc.) In this embodiment, the substrate 9 having information recorded on the surface by unevenness is directly used, but instead of this, a polyolefin, epoxy, acrylic resin, or ultraviolet curable resin layer is used. You may use the chemically strengthened glass etc. which were formed in the surface. Substrate size other than 13 cm,
12 cm, 3.5 inches, 2.5 inches and other sizes may be used.

In this example, two disc members were prepared by the same method, and the two disc members were bonded via an adhesive layer.
The second reflective layers 7 of the first and second disk members,
Although the 7's are bonded to each other, a disk member having another structure or a protective substrate may be used instead of the second disk member.

(Rewritable, super-resolution reproduction type disc)
In addition, instead of the substrate 9 on which information is recorded by the unevenness, FIG.
As described above, a disk configuration may be used in which the substrate 1, the protective layer 11, and the recording film 12 of the continuous groove servo format having the tracking guide unevenness by the continuous groove similar to the substrate 1 described in the first embodiment are used. Also in this case, the number of times of super-resolution reproduction is improved as compared with the case where the diffusion prevention layer 6 is not provided.

The matters not described in this embodiment are the same as those in the first embodiment.
Is the same as

[0146]

In the conventional disc, the layer material diffuses or reacts between the first reflective layer and the second reflective layer during a number of times of super-resolution reproduction, and the thermal conductivity and the optical constant change, resulting in C / C. The decrease in N can be prevented in the disk of the present invention by providing the diffusion preventing layer.

[Brief description of the drawings]

FIG. 1 is a sectional view of an information recording medium according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a conventional information recording medium.

FIG. 3 is a sectional view of an information recording medium according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a conventional information recording medium for comparison with the second embodiment.

FIG. 5 is a sectional view of a rewritable disc for super-resolution reproduction which can be rewritten on the information recording medium of the second embodiment of the present invention.

FIG. 6 is a block diagram of the device of the present invention.

[Explanation of symbols]

1, 1 '... polycarbonate substrate, 2, 2' ... protective layer,
3, 3 '... recording film, 4, 4' ... intermediate layer, 5, 5 '... first
Reflection layer, 6, 6 '... Diffusion prevention layer, 7, 7' ... Second reflection layer, 8 ... Adhesive layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Miyauchi 1-280, Higashi Koigokubo, Kokubunji, Tokyo Metropolitan Research Center, Hitachi, Ltd.

Claims (16)

[Claims] 1. A recording layer or super-resolution thin film for information recording, which is formed on a substrate directly or through an underlayer and records and / or reproduces information by a change in atomic arrangement caused by irradiation of an energy beam. An information recording medium comprising a read mask layer, a protective layer, a plurality of reflective layers, and a diffusion prevention layer on at least one of the interfaces between the reflective layers. 2. The plurality of reflective layers are composed of a first reflective layer, a second reflective layer, and a diffusion prevention layer between the first reflective layer and the second reflective layer, which are made of materials having different refractive indexes or extinction coefficients at the reading laser wavelength. Item 1. The information recording medium according to item 1. 3. A protective layer, a recording layer or a mask layer for super-resolution reading is laminated in this order on the substrate from the light incident side, and then the first reflective layer is directly or via an intermediate layer. The information recording medium according to claim 1, wherein the information recording medium has a structure in which a diffusion prevention layer and a second reflective layer are laminated in this order. 4. The diffusion preventing layer comprises W, Mo, Cr, Ti,
V, Mn, Fe, Co, Ni, Pd, Pt, Cu, Al
-Si, Al-Si-N, SiO 2, Si-N or them as a main component an alloy, a compound, at least one information recording medium according to claim 1 or a composition close thereto, the mixed material . 5. A fluorination, nitridation, oxidation, carbonization, sulfurization, selenization, or halogenation treatment other than fluorination of the first reflection layer material after the final step and / or after the lamination of the first reflection layer. The information recording medium according to claim 1, which is formed by: 6. At least 1% or more of nitrogen, oxygen, chlorine, fluorine, hydrogen sulfide, carbon tetrachloride in the atmosphere gas when the first reflective layer is formed after the final step of laminating the first reflective layer and / or after the lamination. The information recording medium according to claim 1, wherein the diffusion preventing layer is formed by laminating the first reflective layer material using a mixed gas containing at least one of hydrogen and iodine. 7. At least 1% or more of nitrogen, oxygen, chlorine, fluorine, hydrogen sulfide, carbon tetrachloride in an atmosphere gas used for forming the second reflective layer before and / or before the step of laminating the second reflective layer. 2. The information recording medium according to claim 1, wherein the diffusion preventing layer is formed by laminating the second reflective layer material using a mixed gas containing at least one of hydrogen, iodine and the like. 8. The second reflection layer material is subjected to a halogenation treatment other than fluorination, nitridation, oxidation, carbonization, sulfurization, selenization, and fluorination in the first step and / or before the lamination of the second reflection layer. The information recording medium according to claim 1, which is formed by the above. 9. The process of stacking the first reflection layer and the second reflection layer by the diffusion prevention layer, wherein at least one of the reaction prevention treatment and the diffusion prevention treatment is performed on the interface of at least one of the layers. The information recording medium according to claim 1, which is formed by performing. 10. The information recording medium according to claim 1, wherein the first reflective layer is directly laminated on the recording film. 11. The first reflective layer comprises Si, Si-Ge mixed material, Si-N, Si-Sn, Si-Au, or Si.
At least one of the --In mixed materials, or a composition close to this, or the second reflective layer is made of Al--Ti, A
Al-Cu, Al-Cu, Cu-alloy, Al, Cu, Cu alloy, Au, Au alloy, Ag, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W, The information recording medium according to claim 1, which has at least one of W alloy, Co, Co alloy, Pt, and Pt alloy, or a composition close to this. 12. The first reflective layer is Al-Ti, Al-A.
g, Al-Cu, Al-Cr, etc. containing Al alloy as a main component, Al, Cu, Cu alloy, Au, Au alloy, A
g, Ag alloy, Mo, Mo alloy, Ta, Ta alloy, W,
At least one of W alloy, Co, Co alloy, Pt, and Pt alloy, or a composition close to this, or the second reflective layer is Si, Si-Ge mixed material, Si-N, Si
The information recording medium according to claim 1, wherein the information recording medium has at least one of -Sn, Si-Au, or Si-In mixed material, or a composition close to this. 13. The information recording medium according to claim 1, further comprising an intermediate layer between the recording layer or the mask layer for super-resolution reading and the first reflective layer. 14. The protective layer having a thickness of 70 nm or more, 13
The information recording medium according to claim 1, which is in a range of 0 nm or less. 15. In the information recording medium, 95% of the total number of atoms in the recording layer or the mask layer for super-resolution reading.
The above composition is represented by (L) _1-s (H) _s , where L is a phase change component and H is a high melting point component, and satisfies 0.02 ≦ s ≦ 0.20.
An information recording medium according to claim 1. 16. The information recording medium according to claim 1,
A recording / reproducing or super-resolution reproducing wavelength of the medium is provided with a laser, and an optical head control circuit, tracking error detecting means, optical head moving driver, recording data modulating means, laser driver, reproducing signal processing Means, information memory device comprising reproduction data transmission means.