JP2001143318A - Optical information recording medium and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk which is free of deterioration in recording and reproducing quality and is capable of suppressing a cross erase. SOLUTION: At least a first dielectric layer 22, a recording layer 23 of a phase transition type and a second dielectric layer 24 are laminated on a transparent substrate 21 in such a manner that the respective ratios Ds/Df, ts/tf and ds/df of the average film thicknesses Df, tf and df of the first dielectric layer, recording layer and second dielectric layer formed in the groove parts and the flat parts of land parts and the average film thicknesses Ds, ts and ds of the first dielectric layer, recording layer and second dielectric layer formed in the side wall position between the groove parts and the flat parts the land parts and satisfy at least one relation of ts/tf>Ds/Df and ts/tf>ds/df.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rewritable phase-change type recording medium using a substrate on which groove-like irregularities for tracking guide are formed, and to stabilize recording marks formed by laser irradiation. To be formed, and
The present invention relates to a rewritable optical information recording medium having high density and excellent recording / reproducing characteristics by suppressing thermal interference to recording marks recorded on adjacent tracks, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Techniques for reproducing or recording high-density information using a laser beam are well known, and are mainly put to practical use as optical disks. Optical disks can be broadly classified into a read-only type, a write-once type, and a rewritable type. The read-only type has been put into practical use as a compact disk or a laser disk, and the write-once type or rewritable type has been put into practical use as a document file, a data file, or the like. Most rewritable optical disks include magneto-optical disks and phase-change disks. In a phase change optical disk, the recording layer is irradiated with laser light,
Utilizing the fact that reversible state changes occur between an amorphous phase and a crystalline phase (or between a crystalline phase and a crystalline phase having a further different structure). This is because recording is performed by changing at least one of the refractive index and the extinction coefficient of the thin film by irradiating a laser beam, and the amplitude of the transmitted light or reflected light changes at this portion, and as a result, the detection system A change in the amount of transmitted light or reflected light up to the point is detected, and a signal is reproduced. As a material that causes a state change between the amorphous phase and the crystalline phase, alloys such as Te, Se, In, and Sb are mainly used.

[0003] A phase-change optical disk generally has a structure in which a dielectric layer, a recording layer, a reflective layer, and a protective layer are provided on a substrate. As an example of the disk configuration, there is a disk in which a first dielectric layer, a recording layer, a second dielectric layer, a reflective layer, and a protective layer are sequentially stacked on a substrate.

As the dielectric layer, sulfides such as ZnS, S
oxides such as iO ₂ , Ta ₂ O ₅ , Al ₂ O ₅ , GeN, Si ₃
Nitride such as N ₄ , Al ₃ N ₄ , GeON, SiON, Al
Nitride oxides such as ON, other dielectrics such as carbides and fluorides, or appropriate combinations thereof have been proposed.
In general it is often used ZnS-SiO _2.

[0005] Au, Ag, Al, Cr
Or the like, or an alloy of these metals can be used, and is provided for the purpose of heat dissipation and effective light absorption of the recording thin film, but is not an essential layer.

As the protective layer, those obtained by dissolving a resin in a solvent and applying and drying the resin, and those obtained by bonding a resin plate with an adhesive are used.

[0007] The recording layer, the dielectric layer, and the reflective layer are formed on a transparent substrate by a method such as vacuum evaporation or sputtering.

As a material for the substrate, glass, quartz, polycarbonate, or polymethyl methacrylate can be used. In addition, it is general to use a substrate having a groove-shaped unevenness for tracking guide formed on its surface, and when viewed from the incident side of a laser beam for recording and reproducing information, among the unevenness. The distant portion, ie, the convex portion on the disk substrate is called a land, and the near portion, ie, the concave portion on the disk substrate, is called a groove. Hereinafter, in the present specification, the groove slope between the land and the groove is abbreviated as a side wall (surface).

In general, a sputtering method is used for forming the thin film. There are mainly two methods for continuously forming a thin film on a substrate by sputtering. That is, after forming a thin film by discharging the target material with the substrate and the target material of each member facing each other,
A method of continuously forming a thin film of each member by sequentially facing different target materials, or a rotating body (hereinafter referred to as a pallet) to which a plurality of substrates are attached and a target material of each member are opposed to each other to discharge the target material. Generally, a method is used in which a thin film is simultaneously formed on a plurality of substrates by rotating a rotating body, and then a thin film of each member is continuously formed by sequentially facing different target materials.

Hereinafter, a manufacturing method using these conventional techniques will be described.

First, as a first conventional example, a method of sequentially forming a thin film of each member sequentially for each substrate will be described. A target material for forming a recording layer, a dielectric layer, and a reflective layer is provided in a vacuum chamber. With the disk substrate facing a predetermined target material, the vacuum chamber is set to a rare gas or an atmosphere in which a reactive gas such as oxygen or nitrogen is appropriately mixed in the rare gas, and DC is applied to the target material at a predetermined degree of vacuum. Alternatively, a predetermined film is sputtered by applying RF power. At this time, in order to increase the sputtering speed, a magnetic field may be generated on the target to bind the plasma electrons, thereby forming a high-density plasma region called erosion concentrically and performing sputtering. After forming the predetermined member in this manner, the multilayer film disk medium is formed by moving the substrate or the target material and continuously forming the layer of the next member without breaking the vacuum.

In the method of forming a thin film according to the first conventional example, the thickness of the film formed on the side wall is generally smaller than the thickness of the film formed on the flat portion. This is because the substrate is placed facing the target and atoms sputtered from the target material are likely to be incident on the flat portion of the substrate in a vertical direction at a high rate. It is considered that the portion is easily formed thicker than the side wall portion.

Next, as a second conventional example, a pallet on which a plurality of substrates are mounted is opposed to a target material of each member, and the pallet is rotated during discharge of the target material so that a thin film is continuously formed on a plurality of substrates. The method of forming the target will be described. The rotating body on which the plurality of substrates are mounted is carried into a vacuum chamber, and the vacuum chamber is set to a rare gas or an atmosphere in which a reactive gas such as oxygen or nitrogen is appropriately mixed in the rare gas, and a predetermined vacuum degree is set. Then, DC or RF power is applied to the target to perform sputtering of a predetermined film. During discharge of the target material, the pallet is rotating, and the substrates attached to the pallet sequentially pass over the target material, whereby predetermined films are formed on the plurality of substrates.
After the predetermined member is formed in this manner, a layer of the next member is continuously formed without breaking the vacuum to form a multilayer disk medium.

According to the method of forming a thin film according to the second conventional example, the film thickness deposited on the side wall is substantially equal to the film thickness deposited on the flat portion. The reason for this is that the second conventional method of forming a thin film while the substrate passes over the target allows the atoms sputtered from the target material to enter the substrate at various angles with respect to the substrate, It is considered that the ratio of the atoms vertically incident on the flat portion of the substrate and the atoms vertically incident on the side wall surface of the substrate unevenness is substantially equal.

[0015]

At present, there is a demand for higher density and larger capacity optical discs. As a means of increasing the density of an optical disk, a smaller recording mark is formed by using a short-wavelength laser beam, the width of a groove or land on a substrate is reduced, and recording is performed on both tracks of the groove and land. There is a method such as doing.

In recent years, the development of optical discs with a large capacity has been remarkable, and a method of recording data on both grooves and lands has already been adopted in some media. The width of the groove or land is approaching the spot diameter of the laser beam. When the width of the land and groove approaches the irradiation spot diameter, the problem of so-called adjacent erasure (cross-erase) becomes more prominent when writing a signal to an arbitrary track, which easily affects the recording mark of the adjacent track. Is one of the problems.

The main causes of cross erase are as follows:
One of the causes is that the irradiation heat of the laser beam when writing a signal to an arbitrary track diffuses and thermally affects a recording mark written to an adjacent track.

Several proposals have been made so far to suppress cross-erase. For example, JP-A-10-9
JP 2016 discloses that the ratio of the film thickness c covering the side wall to the film thickness a covering the top surface of the land is limited to 0 to 0 by limiting the ratio of the film thickness of the flat portion to the film thickness of the side wall. .8.

Japanese Patent Application Laid-Open No. 11-53763 proposes that the thickness of a recording layer provided on a side wall portion is made smaller than the thickness of a recording layer provided on a groove surface and a land surface. Have been.

In these patent publications, the cross-erase is suppressed by making the thickness of the side wall portion of the recording layer smaller than the thickness of the flat portion, thereby suppressing the heat diffused from the side wall portion to the adjacent track. Has been proposed.

However, if the thickness of the side wall of the recording layer is made smaller than the thickness of the flat portion, the crystal near the side wall becomes less.
A problem arises in that the phase change in the amorphous state cannot be performed properly. The possible causes are described below.

Generally, as the thickness of the recording layer decreases, the heat capacity of the recording layer decreases, and the amount of energy required for phase change decreases. Therefore, the optimum power for phase change, that is, the peak at which a desired carrier-to-noise ratio can be obtained is obtained. The recording sensitivity, which is the ratio between the power and the bias power, decreases. Here, as the thickness of the side wall becomes thinner than the thickness of the flat portion, excessive laser irradiation power is applied to the side wall, and the thermal balance in performing a phase change is lost, and recording is performed. It is considered that the boundary between the mark and the unrecorded portion becomes unclear. This results in a disorder of the shape of the recording mark near the side wall, which causes noise at the time of reproduction and causes a problem of deteriorating the recording / reproduction quality.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an optical information recording medium capable of suppressing cross-erase without deteriorating recording / reproducing quality and a method of manufacturing the same. Is what you do.

[0024]

In order to achieve the above-mentioned object, a first optical information recording medium of the present invention has grooves and lands formed concentrically or spirally on a surface thereof alternately in a radial direction. On a disc-shaped transparent substrate, at least a first dielectric layer, a phase-change recording layer capable of reversible state change between an amorphous phase and a crystalline phase by irradiation with laser light, An optical information recording medium comprising: a first dielectric layer, a recording layer, and a second dielectric layer formed on flat portions of the groove and the land. Each of the average film thicknesses Df, tf, and df, and the first dielectric layer, the recording layer, and the second dielectric layer formed on the sidewall between the flat portion of the groove and the land. Each ratio Ds / Df with each average film thickness Ds, ts, and ds ts / tf, and ds / df is, t
It is characterized by satisfying at least one relationship of s / tf> Ds / Df and ts / tf> ds / df.

In order to achieve the above object, the second aspect of the present invention
The optical information recording medium, on a disk-shaped transparent substrate in which grooves and lands are alternately formed in the radial direction concentrically or spirally on the surface, at least a first dielectric layer, a laser light An optical information recording medium obtained by stacking a phase change recording layer capable of reversible state change between an amorphous phase and a crystalline phase by irradiation, a second dielectric layer, and a reflective layer, The average film thicknesses Df, tf, df, and rf of the first dielectric layer, the recording layer, the second dielectric layer, and the reflective layer formed on the flat portions of the grooves and lands, respectively. An average film thickness Ds of each of the first dielectric layer, the recording layer, the second dielectric layer, and the reflective layer formed on a sidewall between the flat portion of the groove and the land;
The respective ratios Ds / Df, ts to ts, ds, and rs
s / tf, ds / df and rs / rf are ts / tf
> Ds / Df, ts / tf> ds / df, and ts / t
It is characterized in that at least one relationship of f> rs / rf is satisfied and rs / rf is less than 0.9.

According to the first and second optical information recording media, the ratio between the average film thickness in the flat portion of the recording layer and the average film thickness in the side wall portion is determined by comparing the average film thickness in the flat portion of the other layer with the average film thickness in the other layer. Since the ratio with respect to the average film thickness in the side wall portion can be set optimally, it is possible to provide an optical information recording medium without deterioration of recording / reproducing quality and capable of suppressing cross-erase. .

In the second optical information recording medium, the condition that the ratio rs / rf of the average thickness of the reflective layer is less than 0.9 is based on the fact that rs / rf becomes 0.9 or more. This is because the heat is easily transmitted to the adjacent track through the film formed on the side wall portion, so that the cross erase becomes large enough to cause a problem. More preferably,
This is the case where the ratio rs / rf of the average thickness of the reflective layer is less than 0.85.

In the first and second optical information recording media, an average film thickness tf of the recording layer formed on the flat portion of the groove and the land, and a distance between the flat portion of the groove and the land. It is preferable that the ratio ts / tf of the recording layer formed on the side wall portion to the average film thickness ts is 0.80 or more and less than 1.10.

This is because the ratio ts / tf of the average film thickness is 0.8.
If the value is less than 0, excessive laser irradiation power is applied to the side wall portion during information recording, and the thermal balance is lost when performing a phase change, and the shape of the recording mark near the side wall portion is disturbed. This is because noise occurs at the time of reproduction, and the recording / reproduction quality is degraded. Further, when the ratio ts / tf of the average film thickness is 1.10 or more, the ratio of the flat portion of the groove portion or the land portion on the substrate decreases, which is disadvantageous for high density recording. In addition,
More preferably, the ratio ts / tf of the average thickness of the recording layer is 0.90 or more and less than 1.05.

In the first and second optical information recording media, in the first and second optical information recording media, the recording layer formed on the flat portion of the groove and the land may be formed. Average thickness tf is 3 nm or more and 30 nm
It is preferably less than.

This is because when the average thickness tf is less than 3 nm, the phase change material forming the recording layer does not easily form a layer,
Also, this is because the phase change between the crystalline and amorphous states cannot be performed properly. Further, when the average film thickness tf is 30 nm or more, the thermal diffusion in the recording layer surface becomes large, and cross-erase tends to occur when recording is performed at high density. More preferably, the average film thickness tf is 5
In this case, the thickness is not less than 25 nm and less than 25 nm.

Further, in the first and second optical information recording media, the average film thickness Df of the first dielectric layer formed on the flat portion of the groove and the land may be equal to the optical information. Assuming that the wavelength of the laser beam at the time of reading information from the recording medium is λ and the refractive index of the first dielectric layer is n ₁ , 15 · λ / (64 · n ₁ ) or more (40 · λ) / ( 6
It is preferably less than 4 · n ₁ ).

This is because the average film thickness Df is 15 · λ / (64
· N ₁₎ less than (40 · λ) / (becomes a 64 · n ₁₎ or more, it becomes difficult optical design.

In the first and second optical information recording media, the average thickness df of the second dielectric layer formed on the flat portion of the groove and land is 10n.
It is preferably at least m and less than 70 nm.

This is because, when the average film thickness df is less than 10 nm, the recording layer is too close to the reflection layer, and when the recording track is irradiated with the laser beam, the signal of the adjacent track is generated by the heat generation of the reflection layer. Disturbed, jitter increased,
This is because the recording / reproducing quality deteriorates. Also, the average film thickness d
If f is 70 nm or more, the recording layer is gradually cooled and coarse crystals are likely to be formed around the recording marks, which also increases jitter and deteriorates recording / reproducing quality.

Further, in the first and second optical information recording media, the height of the unevenness of the groove and the land is:
Assuming that the wavelength of the laser beam is λ and the refractive index of the real part of the complex refractive index of the substrate is n, λ / (10 · n) or more
(2 · n), and the side wall portion between the groove portion and the flat portion of the land portion is at an angle of 20 ° with respect to the groove portion plane.
It is preferable to form an angle of no less than 70 °.

This is because the height of the unevenness between the groove and the land is λ.
// (10 · n), it is difficult for the laser beam to stably follow the groove or the land, and λ / (2
In the case of n) or more, it is difficult to form a groove stably over the entire circumference of the substrate. The angle formed by the side wall between the groove and the flat part of the land with the plane of the groove is 20 °.
If it is less than the above, the proportion of the flat portion of the groove or land on the substrate is small, which is disadvantageous for high-density recording, and if it is 70 ° or more, it is difficult for heat to be diffused at the bent portion from the flat portion to the side wall portion. This is because it is difficult to stably change the phase of the recording layer.

In order to achieve the above object, a first method for manufacturing an optical information recording medium according to the present invention is a method for manufacturing the second optical information recording medium, wherein A layer, the second dielectric layer, and at least one of the reflective layers, when forming a layer by performing sputtering with the substrate facing a target material, when forming the recording layer, The method is characterized in that a layer is formed by performing sputtering while moving the substrate with respect to the target material.

According to the first manufacturing method, the recording layer
A plurality of substrates are attached to a pallet opposed to the target material described in the conventional example, and a thin film of each member is continuously formed on the plurality of substrates by rotating the pallet during discharge of the target material. At least one of the dielectric layer, the second dielectric layer, and the reflective layer is formed by continuously forming a thin film of each member on each of the substrates described in the conventional example, so that the ratio of the average film thickness is reduced. ts / tf> Ds / Df, ts / tf> ds / d
Each layer can be formed so as to satisfy at least one of f and ts / tf> rs / rf.

In order to achieve the above object, a second method for manufacturing an optical information recording medium according to the present invention comprises the first and second optical information recording media.
Wherein the erosion of plasma discharge formed concentrically is formed two or more on a target material, and the recording layer is formed by magnetron sputtering.

According to the second manufacturing method, the target material can be used in a wider range by forming two or more erosions, so that the target material can be sputtered from various angles with respect to the substrate. Atoms can be made incident, and the ratio of atoms incident in the direction perpendicular to the side wall surface of the substrate unevenness increases, so that the film thickness of the side wall portion of the recording layer can be made larger than the film thickness of the flat portion. Becomes

In order to achieve the above object, a third method of manufacturing an optical information recording medium according to the present invention comprises the first and second optical information recording media.
The method for producing an optical information recording medium according to claim 1, wherein at least two or more target materials are used, and a shielding plate is arranged between the target materials and the substrate when forming the recording layer. And

According to the third manufacturing method, sputtered atoms from one of the target materials, on which the substrate is disposed above and the shielding plate is disposed between the substrate and the inner peripheral side than the side wall or the flat portion on the outer peripheral side of the medium. The sputtering atoms from the other target material are conversely deposited thicker on the outer peripheral side than on the inner peripheral side wall or the flat part, so that the total The thickness of the recording layer can be made substantially equal to the thickness of the recording layer in the flat portion.

In the first to third manufacturing methods, the pressure in the vacuum chamber at the time of forming the recording layer depends on the pressure of the first dielectric layer, the second dielectric layer, and the reflective layer. It is preferable that the pressure is higher than the pressure in the vacuum chamber when forming at least one of the layers.

According to this method, the higher the pressure, the shorter the mean free path, and the easier it is for the sputtered atoms to be diffused. Average thickness ratio ts of layer
/ Tf can be increased.

[0046]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

One form of the optical information recording medium shown in FIG.
On the substrate 11, a first dielectric layer 12, a recording layer 13, a second dielectric layer 14, and a reflective layer 15 are laminated in this order. FIG. 2 is a schematic enlarged view of a part of FIG. 1. Df indicates a film thickness in a flat portion of the first dielectric layer 22, and Ds indicates a film in a side wall portion of the first dielectric layer 22. Tf indicates a film thickness in a flat portion of the recording layer 23, ts indicates a film thickness in a side wall portion of the recording layer 23, and d
f indicates the film thickness in the flat portion of the second dielectric layer 24,
ds indicates the film thickness at the side wall of the second dielectric layer 24, rf indicates the film thickness at the flat portion of the reflective layer 25, and r
s indicates the film thickness on the side wall of the reflective layer 25.

However, the present invention is not limited to the above configuration, and a material layer may be appropriately inserted between the first dielectric layer and the recording layer or / and between the recording layer and the second dielectric layer. Is also good. Also, at least one or more material layers may be inserted between the second dielectric layer and the reflective layer as appropriate. In addition, a configuration in which a reflective layer is not provided may be adopted. In this case, at least one or more material layers may be provided on the second dielectric layer as appropriate.

As the material of the substrate, polycarbonate,
A resin such as PMMA, glass, or the like is used, and a guide groove for guiding a laser beam is provided.

The height of the unevenness of the groove portion and the land portion of the guide groove is
When the wavelength of the laser beam to be used is λ, and the refractive index of the real part in the complex refractive index of the substrate is n, λ / (10 · n) or more and less than λ / (2 · n) are satisfied, and the groove and the land are provided. Is preferably at an angle of not less than 20 ° and less than 70 ° with respect to the groove plane. If the height of the unevenness between the groove and the land is less than λ / (10 · n), it becomes difficult for the laser beam to stably follow the groove or the land, and
This is because if it is (2 · n) or more, it is difficult to form a groove stably over the entire circumference of the substrate.

If the slope between the groove and the land is less than 20.degree. With respect to the plane of the groove, the ratio of the flat part of the groove or land on the substrate is small, which is disadvantageous for high-density recording. If it is more than °, it becomes difficult for heat to be diffused at the curved part from the flat part to the slope,
This is because it is difficult to stably change the phase of the recording layer.

In the present embodiment, as the material of the substrate, polycarbonate having a refractive index of 1.45 with respect to light of 650 nm, which is a reading laser wavelength of the optical information recording medium, is used. In addition, the height of the unevenness of the groove and the land is 550 n.
m, the track pitch of the substrate was 0.60 micron meter, and a substrate having irregularities in which the slope between the groove and the land made an angle of 50 ° with the plane of the groove was used. Of course, substrates having different width ratios between the groove and the land may be used.

The material of the first dielectric layer and the second dielectric is preferably a thermally stable material.
S, ZnSe, ZnTe, ZnPo, ZnC, ZnS
i, ZnGe, ZnSn, ZnP, ZnAs, ZnS
b, zinc compound such as ZnBi or Al, Ga, I
oxides such as n, Tl, Si, Ti, Zr, Hf, and Cu;
It is preferable that the material contains at least one of materials such as nitride, fluoride, carbide, and sulfide.
Here, the first dielectric layer and the second dielectric layer may be the same material or different materials.

In the present embodiment, a mixture of ZnS and SiO ₂ is used as the material of the first dielectric layer and the second dielectric.

The average thickness of the first dielectric layer formed on the flat portion is 15 · λ / (64) with respect to the wavelength λ of the readout laser and the refractive index n _{1 of} the first dielectric layer. · N ₁ ) or more and less than (40 · λ) / (64 · n ₁ ). 15 ・
λ / (64 · n ₁ ) or less or (40 · λ) / (64
If n ₁ ) or more, optical design becomes difficult.

The mixture of ZnS and SiO ₂ used in the present embodiment has a refractive index of 2.10 for light of 650 nm, which is a reading laser wavelength of an optical information recording medium. The thickness of the dielectric layer in the flat part was 150 nm.

The average thickness of the second dielectric layer formed on the flat portion is preferably from 10 nm to less than 70 nm, more preferably from 20 nm to less than 50 nm. 10
If it is less than nm, the recording layer will be too close to the reflective layer, and when a track to be recorded is irradiated with an optical laser, the heat generated by the reflective layer will disturb the signal of the adjacent track, thus deteriorating jitter. On the other hand, if the thickness is 70 nm or more, the recording layer is gradually cooled, and coarse crystals are easily formed around the recording marks, so that the jitter is deteriorated.

In the present embodiment, the thickness of the second dielectric layer at the flat portion is 40 nm.

As the material of the recording layer, a material whose optical characteristics change reversibly is used. In the case of a phase change recording medium, S
It is preferable to use a b-based or chalcogenide-based material containing Te or Se. For example, TeSeGe, TeSn
Ge, TeSbGeSe, TeSnGeAu, AgIn
Materials including SbTe, InSbSe, InTeSe, and the like can be given. The recording layer may contain sputter gas components such as Ar and Kr, H, C, H ₂ O, etc. as impurities, and also add a small amount of another material for various purposes (for example, about 10 at%). The following configuration may be used, but these configurations are not excluded in the present invention. In this embodiment, a GeSbTe-based alloy is used.

The average thickness of the recording layer formed on the flat portion is preferably 3 nm or more and less than 30 nm, more preferably 5 nm or more and less than 25 nm. This is because when the film thickness is less than 3 nm, the recording material is hardly formed into a layer, and the phase change from the crystalline state to the amorphous state is not performed properly. When the film thickness is 30 nm or more, the heat diffusion in the recording layer surface increases. This is because adjacent recording is likely to occur when recording is performed at high density. In the present embodiment, the film thickness at the flat portion of the recording layer is 10 nm or more and 20 n
m or less.

The average thickness ts of the recording layer formed on the side wall is equal to the average thickness tf of the recording layer formed on the flat portion.
Is ts / tf> ds / df or /
And ts / tf> Ds / Df or / and ts / tf
> 3 nm or more, and more preferably 5 nm or more, in a range satisfying the relationship of> rs / rf. Further, ts / tf is preferably 0.8 or more and less than 1.10, more preferably 0.9 or more.
It is less than 05. Here, ds is the average film thickness formed on the side wall of the second dielectric layer, df is the average film thickness formed on the flat portion of the second dielectric layer, and Ds is the first dielectric film. The average film thickness formed on the side wall of the body layer, Df is the average film thickness formed on the flat portion of the first dielectric layer, and r
s is the average film thickness formed on the side wall of the reflective layer, and r
f is the average film thickness formed on the flat portion of the reflection layer. t
If s is less than 3 nm, the recording material is unlikely to be layered, and the phase change between the crystalline and amorphous states cannot be performed properly. In the present embodiment, various studies have been made on the film thickness formed on the side wall portion.

The reflecting layer is made of Au, Ag, Cu, Al, Cr,
It is formed of a metal such as Ni or an alloy of a suitably selected metal. Average film thickness r of reflective layer formed on side wall
As for s, the ratio rs / rf to the average film thickness rf of the reflective film formed on the flat portion is desirably less than 0.9, more preferably less than 0.85. If the ratio is 0.9 or more, heat is easily transmitted to an adjacent track through the film formed on the side wall portion, and cross erase is increased.

In this embodiment, the Au reflection layer is formed to have a thickness of 160 nm in the flat portion.

Next, a method for manufacturing an optical information recording medium will be described.

First, an example of a recording layer sputtering method will be described with reference to the schematic diagram of FIG. FIG. 3 shows an example in which a first erosion 32 and a second erosion 33 are formed on a target. A target material for a recording layer is arranged at a position opposite to the upper portion of the substrate 31, and two or more electromagnetic coils or permanent magnets are placed below the target material for the recording layer. To be formed in The substrate 31 is preferably arranged directly above the target material, and the area of the target material is preferably equal to or larger than the substrate area.

According to the recording layer sputtering method shown in FIG. 3, by forming two or more erosions,
Since the target material can be used in a wider range, atoms sputtered from the target material can be incident from various angles with respect to the substrate, and are incident perpendicularly to the side wall surface of the substrate unevenness. It is considered that the ratio of atoms is increased, and a film is easily deposited on the side wall.

Next, another example of the recording layer sputtering method will be described with reference to FIG. A first target material 42 and a second target material 43 for a recording layer are arranged at a position facing the substrate 41. Here, the target material 42 and the target material 43 may have the same material composition or different material compositions. The substrate 41 is disposed above the target material 42, and a shielding plate 44 is provided between the substrate 41 and the target material 42. Sputtering atoms from the two target materials 42 and 43 are deposited on the substrate 41 while rotating the substrate 41 to form a recording layer.

According to the recording layer sputtering method shown in FIG. 4, by sputtering from two targets, sputtered atoms from the target material 43 are deposited on the inner peripheral side wall and the outer peripheral side wall than the flat part. On the other hand, since the sputtering atoms from the target material 42 are deposited thicker on the inner peripheral side wall than the outer peripheral side wall and the flat part, the recording layer thickness on the side wall part is totally increased. Is considered to be substantially equal to the recording layer thickness at the flat portion.

FIG. 5 shows a film forming apparatus for forming an optical information recording medium according to the embodiment of the present invention.

A vacuum pump (not shown) is connected to the vacuum vessel 51 through an exhaust port so that the inside of the vacuum vessel 51 can be maintained at a high vacuum. A cryopump, a mechanical booster pump, and a rotary pump are provided as vacuum pumps, and can be used as appropriate. From the gas supply port 52, a constant flow rate of an inert gas, a reactive gas such as nitrogen or oxygen, or a mixed gas thereof can be supplied. The substrates 53 are attached to a plurality of substrate holders 55 provided on a rotary pallet 54, and each substrate holder 55 can rotate independently of the rotary pallet 54. After the rotary pallet 54 is sufficiently evacuated in the vacuum preliminary tank 56,
It can be transported to the vacuum vessel 51.

The target material 57 for the dielectric layer, the target material 58 for the first recording layer,
A sputtering target of a second recording layer target material 59, a third recording layer target material 60, and a reflection layer target material 61 is provided, and each is connected to a cathode.

Here, the recording layer target material 59 includes:
A plurality of erosions shown in FIG. 1 can be formed. In the present embodiment, a target material having a diameter of 130 mm is used to form two concentric erosions coaxial with the target material. Formed at the position of φ50mm, the outer erosion is φ
It is formed at a position of 95 mm.

Further, two or more targets shown in FIG. 4 can be provided as the third recording layer target material 60. In this embodiment, two target materials 601 and 602 are provided. I have. Further, a shielding plate 62 is provided between the two target materials 601 and 602 and the rotary pallet 54 which is transported when actually performing sputtering. Although not shown in the figure, the cathode is connected to a DC power supply or an RF power supply through a switch. A shutter 63 is provided above each target material to prevent contamination on each target material. Note that the vacuum container 51 and the shutter 63 are connected to the ground.

Next, a method for manufacturing an optical information recording medium according to the present invention using the present apparatus will be described. First dielectric layer 12, second dielectric layer 14, and reflective layer 1 shown in FIG.
When at least one of the layers 5 was formed, the rotary pallet 54 was stopped and the substrate 53 was formed so as to face the target material for each layer (hereinafter, referred to as a forming method 1). Each layer was formed on the substrate by rotating the rotary pallet 54 so that each substrate 53 passed at least once over the target material. Here, the substrate holder 55 may be rotated or not, but is rotated in the present embodiment.

When the recording layer 13 was formed, it was formed by any of the following forming methods.

1) With the recording layer target material 58 discharged, the rotary pallet 54 is rotated so that each substrate 53 passes over the target material 58 at least once. The recording layer 13 was formed (formation method 2). Here, the substrate holder 55 may or may not be rotated. However, the substrate holder 55 is rotated because the rotation facilitates uniformity of the film thickness over the entire circumference of the substrate.

2) The substrate holder 55 is fixed at a position facing the recording layer target material 59, and recording is performed on the first dielectric layer 12 previously formed on the substrate 53 while rotating the substrate holder 55. The layer 13 was formed (referred to as forming method 3).

3) The substrate holder 55 is fixed at a position facing the recording layer target material 60, and recording is performed on the first dielectric layer 12 previously formed on the substrate 53 while rotating the substrate holder 55. The layer 13 was formed (referred to as forming method 4).

At this time, when the recording layer 13 is formed,
Various gases were prepared by mixing Ar and a predetermined amount of nitrogen while changing the total pressure or the sputtering power. Total pressure is 0.1
The sputtering power is variable in the range of 33 Pa to 1.333 Pa, and the sputtering power is 12.7 kW / m ² DC at the cathode.
And When forming the first dielectric layer 12 and the second dielectric layer 14, Ar gas is supplied at a constant flow rate so that the total pressure becomes 0.266 Pa, and RF 53.0 kW is applied to the cathode.
/ M ² was applied to perform sputtering.
When forming the reflective layer 15, Ar gas is supplied at a total pressure of 0.1.
It is supplied at a constant flow rate to 400 Pa, and D is supplied to the cathode.
C53.0 W / m ² power was applied to perform sputtering, and a predetermined film thickness was sequentially formed.

A method of sequentially forming a thin film of each target material on a substrate-by-substrate basis by the film forming apparatus shown in FIG. 5, and mounting a plurality of substrates on a rotary pallet 54 facing the target material, A method of continuously forming a thin film of each target material on a plurality of substrates by rotating a rotary pallet 54 during discharge of a target material, and fixing a substrate holder 55 at a position facing a target material 59 for a recording layer. And forming the recording layer 13 while rotating the substrate holder 55, and forming the recording layer 13 while rotating the substrate holder 55 by fixing the substrate holder 55 at a position facing the target material 60 for the recording layer. Were formed, and cross-sectional TEM observations of the thin films were performed.

Table 1 shows the average film thickness Ds (or ds), ts, and rs of the dielectric layer, the recording layer, and the side wall of the reflective layer obtained as a result of cross-sectional TEM observation. The thickness Df (or df), the ratio of tf, rf, Ds / Df (or ds / df), ts / tf, and rs / rf are shown. In the recording layer, the results in which the ratio ts / tf showed the lowest value and the result in which the ratio ts / tf showed the highest value among the thin films prepared variously by changing the sputtering pressure are described.

[0082]

[Table 1]

As shown in Table 1, in the forming method 1, the ratio Ds / Df (or ds / df) between the average film thickness of the dielectric layer, the recording layer, and the reflective layer and the average film thickness in the flat portion is obtained. ),
Both ts / tf and rs / rf decreased.
That is, the thickness of the flat portion was equal to or larger than the thickness of the side wall portion.
The ratio ts / tf of the average film thickness in the recording layer changed in the range of 0.62 to 0.83 according to the pressure at which sputtering was performed, and the ratio increased as the pressure increased. It is considered that this is because the higher the pressure, the shorter the mean free path, and the more easily the sputtered atoms are diffused, so that the ratio of incidence in the direction perpendicular to the side wall surface of the substrate unevenness is increased.

In the formation method 2, the ratio Ds / Df (or ds / df) of the average film thickness of the dielectric layer, the recording layer, and the side wall portion to the average film thickness of the flat portion, and ts / t
f and rs / rf are larger than those in the formation method 1, and
Here, the ratio ts / tf of the average film thickness in the recording layer also increased as the pressure during sputtering increased.

In the formation methods 3 and 4, the ratio of the average film thickness at the side wall of the recording layer to the average film thickness at the flat portion is Ds / D.
f (or ds / df), ts / tf, and rs / rf
Was larger than in the formation method 2, and here, as the pressure at the time of sputtering was higher, the ratio ts / tf of the average film thickness in the recording layer was larger.

[0086]

EXAMPLES By combining the above-described manufacturing methods in various ways, a first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed to manufacture an optical information recording medium (disk medium). An example will be described below.

(Example 1) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. For the formation of the recording layer, the pressure at the time of sputtering was set to 0.133 Pa by the method of the formation method 2 and 15
The other layers were formed to a predetermined thickness by the formation method 1. At this time, as shown in Table 1, a ratio t between the average film thickness of the side wall portion of the recording layer and the average film thickness of the flat portion is obtained.
s / tf is 0.95, the first and second dielectric layers,
The ratios Ds / Df (= ds / df) and rs / rf of the average film thickness at the side wall portion and the average film thickness at the flat portion of the reflective layer were 0.85 and 0.81, respectively. After that, after applying an overcoat layer to create a disk and initializing,
The evaluation was performed with an evaluation device.

(Example 2) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. Discs were prepared and evaluated in the same manner as in Example 1 except that the sputtering pressure when forming the recording layer was 1.333 Pa. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 1.02, and the first and second dielectric layers, and The ratio Ds / Df (= ds / df) of the average film thickness at the side wall portion of the reflective layer to the average film thickness at the flat portion, rs /
rf was 0.85 and 0.81, respectively.

(Example 3) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. A disk was prepared and evaluated in the same manner as in Example 1 except that the thickness of the recording layer was changed to 10 nm. At this time, the ratio ts / tf of the average thickness of the side wall portion of the recording layer to the average thickness of the flat portion is 0.95, and the average of the side wall portions of the first and second dielectric layers and the reflective layer is 0.95. Ratio Ds / Df (= ds / df) of film thickness to average film thickness at flat portion, r
s / rf was 0.85 and 0.81, respectively.

(Example 4) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. A disk was prepared and evaluated in the same manner as in Example 1 except that the thickness of the recording layer was changed to 20 nm. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.9.
5, the ratio Ds / Df of the average thickness of the side walls of the first and second dielectric layers and the reflective layer to the average thickness of the flat portions.
(= Ds / df), rs / rf is 0.85,
It was 0.81.

(Example 5) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. For the formation of the recording layer, the pressure at the time of sputtering was set to 0.133 Pa by the method of the formation method 3 and 15
The other layers were formed to a predetermined thickness by the formation method 1. At this time, as shown in Table 1, a ratio t between the average film thickness of the side wall portion of the recording layer and the average film thickness of the flat portion is obtained.
s / tf is 0.98, the first and second dielectric layers,
The ratios Ds / Df (= ds / df) and rs / rf of the average film thickness at the side wall portion and the average film thickness at the flat portion of the reflective layer were 0.85 and 0.81, respectively. After that, after applying an overcoat layer to create a disk and initializing,
The evaluation was performed with an evaluation device.

(Example 6) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. In forming the first and second dielectric layers,
A disk was prepared and evaluated in the same manner as in Example 5 except that the forming method 2 was used. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.98, and the first and second dielectric layers, and The ratios Ds / Df (= ds / df) and rs / rf of the average film thickness on the side wall portion and the average film thickness on the flat portion of the reflective layer were 0.96 and 0.81, respectively.

(Example 7) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having a concave and convex groove. A disk was prepared and evaluated in the same manner as in Example 5, except that the sputtering pressure when forming the recording layer was 1.333 Pa. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 1.07, and the first and second dielectric layers, and The ratio Ds / Df (= ds / df) of the average film thickness at the side wall portion of the reflective layer to the average film thickness at the flat portion, rs /
rf was 0.85 and 0.81, respectively.

(Example 8) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having a concave and convex groove. For the formation of the recording layer, the pressure at the time of sputtering was set to 0.133 Pa by the method of the formation method 4 and 15
The other layers were formed to a predetermined thickness by the formation method 1. At this time, as shown in Table 1, a ratio t between the average film thickness of the side wall portion of the recording layer and the average film thickness of the flat portion is obtained.
s / tf is 0.97, the first and second dielectric layers,
The ratios Ds / Df (= ds / df) and rs / rf of the average film thickness at the side wall portion and the average film thickness at the flat portion of the reflective layer were 0.85 and 0.81, respectively. After that, after applying an overcoat layer to create a disk and initializing,
The evaluation was performed with an evaluation device.

(Example 9) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having a concave and convex groove. In forming the first and second dielectric layers,
A disk was prepared and evaluated in the same manner as in Example 8 except that the forming method 2 was used. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.97, and the first and second dielectric layers, and The ratios Ds / Df (= ds / df) and rs / rf of the average film thickness on the side wall portion and the average film thickness on the flat portion of the reflective layer were 0.96 and 0.81, respectively.

(Example 10) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. A disk was prepared and evaluated in the same manner as in Example 8, except that the sputtering pressure at the time of forming the recording layer was 1.333 Pa. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 1.09, and the first and second dielectric layers, and The ratio Ds / Df (= ds / df) of the average film thickness at the side wall portion of the reflective layer to the average film thickness at the flat portion, rs /
rf was 0.85 and 0.81, respectively.

(Example 11) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having a concave and convex groove. For the formation of the recording layer, the pressure at the time of sputtering was set to 0.133 Pa by the method of the formation method 2 and 15
The first dielectric layer and the reflective layer were formed to have a predetermined thickness by the formation method 1, and the second dielectric layer was formed to have a predetermined thickness by the formation method 2. At this time,
As shown in Table 1, the ratio ts / tf of the average thickness of the side wall portion of the recording layer to the average thickness of the flat portion is 0.95, and the first dielectric layer, the second dielectric layer, And the ratio Ds / Df, ds / of the average film thickness of the side wall portion and the average film thickness of the flat portion in the reflective layer.
df and rs / rf are 0.85, 0.96, and.
It was 81. Thereafter, a disc was prepared by applying an overcoat layer, and after initialization, evaluation was performed by an evaluation apparatus.

(Example 12) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having a concave and convex groove. Example 11 except that the second dielectric layer and the reflective layer were formed to have a predetermined thickness by the forming method 1, and the first dielectric layer was formed to have the predetermined thickness by the forming method 2.
A disk was created and evaluated in the same manner as described above. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.95,
The ratio Ds / Df, d of the average thickness of the first dielectric layer, the second dielectric layer, and the sidewall thickness of the reflective layer to the average thickness of the flat portion.
s / df and rs / rf are 0.96 and 0.85, respectively.
It was 0.81.

(Example 13) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having a concave and convex groove. A disk was prepared in the same manner as in Example 11 except that the reflective layer was formed to a predetermined thickness by the forming method 1, and the first and second dielectric layers were formed to the predetermined thickness by the forming method 2. ,evaluated. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.95, and the first dielectric layer,
The ratio Ds / Df, ds / df, rs / D of the average thickness of the side wall portion of the second dielectric layer and the reflective layer to the average thickness of the flat portion.
rf was 0.96, 0.96, and 0.81, respectively.

The following is a comparative example.

(Comparative Example 1) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate having an uneven groove. All layers were formed by the formation method 1. In the formation of the recording layer, a pressure of 0.133 Pa was used at the time of sputtering to form a film having a thickness of 15 nm. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.62, and the first and second dielectric layers, and The ratio Ds / Df (= ds) of the average film thickness at the side wall portion of the reflective layer to the average film thickness at the flat portion.
/ Df) and rs / rf were 0.85 and 0.81, respectively. Thereafter, a disc was prepared by applying an overcoat layer, and after initialization, evaluation was performed by an evaluation apparatus.

(Comparative Example 2) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. All layers were formed by the formation method 2, and in the formation of the recording layer, a pressure of 0.133 Pa was used at the time of sputtering to form a film having a thickness of 15 nm. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 0.95, and the first and second dielectric layers, and The ratio Ds / Df (= ds) of the average film thickness at the side wall portion of the reflective layer to the average film thickness at the flat portion.
/ Df) and rs / rf were 0.96 and 0.96, respectively. Thereafter, a disc was prepared by applying an overcoat layer, and after initialization, evaluation was performed by an evaluation apparatus.

(Comparative Example 3) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. All layers were formed by the formation method 2. In the formation of the recording layer, a film thickness of 15 nm was formed at a sputtering pressure of 1.333 Pa. At this time, as shown in Table 1, the ratio ts / tf of the average film thickness at the side wall portion of the recording layer to the average film thickness at the flat portion was 1.02, and the first and second dielectric layers, and The ratio Ds / Df (= ds) of the average film thickness at the side wall portion of the reflective layer to the average film thickness at the flat portion.
/ Df) and rs / rf were 0.96 and 0.96, respectively. Thereafter, a disc was prepared by applying an overcoat layer, and after initialization, evaluation was performed by an evaluation apparatus.

(Comparative Example 4) A first dielectric layer, a recording layer, a second dielectric layer, and a reflective layer were sequentially formed on a substrate on which concave and convex grooves were formed. For the formation of the recording layer, the pressure at the time of sputtering was set to 1.333 Pa by the method of the formation method 3 for 15 minutes.
The first and second dielectric layers were formed to a predetermined thickness by the formation method 1, and the reflective layer was formed by the formation method 2. At this time, as shown in Table 1, the ratio ts / t of the average film thickness at the side wall portion of the recording layer and the average film thickness at the flat portion was obtained.
f is 1.07, and the ratio D of the average film thickness of the first and second dielectric layers and the reflection layer to the average film thickness at the side wall portion and the average film thickness at the flat portion.
s / Df (= ds / df) and rs / rf are each 0.
85 and 0.96. Thereafter, a disc was prepared by applying an overcoat layer, and after initialization, evaluation was performed by an evaluation apparatus.

The recording and reproducing characteristics of the disk media prepared in the examples and comparative examples were evaluated.

A method for evaluating the recording / reproducing characteristics of the disk medium produced in this embodiment will be described. Recording and erasing of the evaluation signal are performed by first rotating the medium by a rotation control device, narrowing the laser beam to a minute spot by an optical system, and irradiating the medium with the laser beam. The amorphous state generating power level at which a local portion of the recording layer can be reversibly changed to an amorphous state by irradiation with laser light is P1, and a crystal that can be reversibly changed to a crystalline state by irradiation with laser light. The state generation power level 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,
Performs erasure and overwrite recording. Here, when irradiating the power of P1, a so-called multi-pulse formed by a train of pulses is used. However, the configuration may be made without using multi-pulses.

Further, the optical level of the recording mark is lower than any one of the power levels P1 and P2, and the optical state of the recording mark is not affected by the irradiation of the laser beam at the power level. Power level at which sufficient reflected light can be obtained for reproduction power level P
The signal is read from a medium obtained by irradiating a laser beam having a power of P3 with a detector, and an information signal is reproduced.

Various conditions are, for example, as follows. The wavelength of the laser beam was 650 nm, the numerical aperture of the objective lens used was 0.60, the signal system was an EFM modulation system, the shortest bit length was 0.28 μm, and the scanning speed of the laser beam in the track direction was 8 m / s. .

The evaluation of the characteristics is as follows. In successive five tracks a, b, c, d, and e, 1T from 3T to 11T in the order of a, e, b, d, and c (T is the clock of the recording data signal) after recording a random signal with a period) increments, measuring the jitter value J ₁ reproduces a signal from the track c, sequentially a, e, c, b, in increments of 1T 3T to in the order of d to 11T After recording a random signal, the signal was reproduced from track c and the jitter value J ₂ was measured. Where J ₁
The disc medium was evaluated as ◎ when the difference between J and J ₂ was less than 0.3, ○ when it was 0.3 or more and less than 1.0, and x when it was 1.0 or more.

The evaluation result was obtained by calculating the ratio ts of the average film thickness of each layer.
It is shown in Table 2 together with / tf, Ds / Df, ds / df, and rs / rf.

[0111]

[Table 2]

From the results in Table 2, it can be seen that Examples 1 to 13 were used.
As shown in the figure, the ratio ts / tf between the average film thickness tf of the flat portion and the average film thickness ts of the side wall portion in the recording layer is 0.80 or more and less than 1.10, and ts / tf and the first The ratio Ds / Df of the average film thickness Df, df, and rf of the flat portion to the average film thickness Ds, ds, and rs of the side wall portion in each of the dielectric layer, the second dielectric layer, and the reflective layer; ds / d
ts / tf> Ds / D between f and rs / rf
f, ts / tf> ds / df, and ts / tf> rs /
When at least one relationship of rf is satisfied,
It can be seen that good evaluation results can be obtained.

Further, as shown in Comparative Examples 1 and 2, disks having a thickness less than the above range, and as shown in Comparative Examples 2 to 4, the average film thickness formed on the side wall of the reflective layer. ratio r between rs and the average film thickness rf formed on the flat portion
It can be seen that a disk having an s / rf of 0.9 or more does not show good results.

In the comparative example shown here, the recording layer thickness was 1
Although the thickness was set to 5 nm, the result was the same even when the film thickness was set to any other value.

Further, in the present embodiment, an example is shown in the configuration in which the reflective layer is provided. However, it can be easily presumed that the present invention is effective even in a configuration in which the reflective layer is not provided.

Further, regarding the substrate used in this example,
Although the side wall between the groove and the land with respect to the groove plane was formed using a substrate having an angle of 50 ° this time, the present invention can be performed using a substrate having any angle within the scope of the claims. It is easy to see that universality is not compromised.

Further, the recording layer is formed by a manufacturing method in which a film is easily deposited on the side wall, and the first dielectric layer, the second dielectric layer, and the reflective layer are hardly deposited on the side wall. The manufacturing method for the method is not limited to the above embodiment, and other modifications are possible.

[0118]

As described above, according to the present invention, the ratio between the average film thickness in the flat portion of the recording layer and the average film thickness in the side wall portion is set to 0.80 or more and less than 1.10, and this ratio is set. By optimally setting the ratio between the average film thickness in the flat portion of the other layer and the average film thickness in the side wall portion, optical information recording that does not deteriorate recording / reproducing quality and can suppress cross-erase It is possible to provide a medium and a method for manufacturing the medium.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a laminated structure of an optical information recording medium according to an embodiment of the present invention.

FIG. 2 is a partially enlarged view of the optical information recording medium shown in FIG.

FIG. 3 is a schematic view showing an example of a recording film sputtering method according to an embodiment of the present invention.

FIG. 4 is a schematic view showing another example of the recording film sputtering method according to the embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a film forming apparatus for producing an optical information recording medium according to an embodiment of the present invention.

[Explanation of symbols]

 11, 21, 31, 41, 53 Substrate 12, 22 First dielectric layer 13, 23 Recording layer 14, 24 Second dielectric layer 15, 25 Reflective layer 32 First erosion 33 Second erosion 42, 43 Target material for recording layer 44, 62 Shielding plate 51 Vacuum container 52 Gas supply port 54 Rotary pallet 55 Substrate holder 56 Vacuum reserve tank 57 Target material for dielectric layer 58, 59, 60 Target material for recording layer 61 For reflective layer Target material 62 Shielding plate 63 Shutter 601, 602 Target material for recording layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshitaka Sakagami 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Terms (reference) 2H111 EA04 EA12 EA23 EA32 EA37 EA41 FA01 FA12 FA21 FA40 GA01 GA03 5D029 JB18 JB35 LB07 NA21 WB03 WB17 WC04 WC05 WD11

Claims (11)

[Claims] 1. A disk-shaped transparent substrate having grooves and lands alternately radially formed concentrically or spirally on a surface thereof, at least a first dielectric layer and an amorphous layer formed by irradiation with a laser beam. An optical information recording medium in which a phase change type recording layer capable of reversible state change between a phase and a crystal phase, and a second dielectric layer are laminated, wherein the groove and the land are flat. Average thicknesses Df, tf, and df of each of the first dielectric layer, the recording layer, and the second dielectric layer formed in the portion, and a sidewall between the flat portion of the groove portion and the land portion. The respective ratios Ds / Df, ts / tf to the average film thicknesses Ds, ts, and ds of the first dielectric layer, the recording layer, and the second dielectric layer formed in the portion, respectively; ds / df
Are ts / tf> Ds / Df and ts / tf> ds /
An optical information recording medium characterized by satisfying at least one relationship of df. 2. A disk-shaped transparent substrate having grooves and lands alternately radially formed concentrically or spirally on a surface thereof, at least a first dielectric layer and an amorphous layer formed by laser light irradiation. An optical information recording medium comprising a stack of a phase-change recording layer capable of reversible state change between a phase and a crystalline phase, a second dielectric layer, and a reflective layer, wherein the groove and Average film thickness Df, tf, df, and rf of each of the first dielectric layer, the recording layer, the second dielectric layer, and the reflective layer formed on the flat portion of the land portion
An average film thickness Ds of each of the first dielectric layer, the recording layer, the second dielectric layer, and the reflective layer formed on a sidewall between the flat portion of the groove and the land; ts, d
s and rs, respectively, Ds / Df, ts / t
f, ds / df and rs / rf are ts / tf> Ds
/ Df, ts / tf> ds / df, and ts / tf> r
s / rf is satisfied, and rs /
An optical information recording medium, wherein rf is less than 0.9. 3. The optical information recording medium according to claim 1, wherein an average thickness tf of the recording layer formed on the flat portion of the groove and the land, and an average thickness tf of the groove and the land. The ratio ts / tf of the recording layer formed on the side wall between the flat portions to the average film thickness ts is 0.80 or more and 1.80 or more.
An optical information recording medium characterized by being less than 10. 4. The optical information recording medium according to claim 1, wherein an average film thickness tf of the recording layer formed on the flat portion of the groove and the land is 3
An optical information recording medium having a thickness of at least 30 nm and less than 30 nm. 5. The optical information recording medium according to claim 1, wherein an average film thickness Df of the first dielectric layer formed on the flat portion of the groove and the land is equal to the optical film thickness. Assuming that the wavelength of the laser beam when reading information from the information recording medium is λ and the refractive index of the first dielectric layer is n ₁ , 15 · λ / (64 · n ₁ ) or more (40 · λ) / (6
(4 · n ₁ ). 6. The optical information recording medium according to claim 1, wherein an average film thickness df of the second dielectric layer formed on the flat portion of the groove and the land is 10n.
An optical information recording medium having a length of at least m and less than 70 nm. 7. The optical information recording medium according to claim 1, wherein the height of the concave and convex portions of the groove and the land is such that the wavelength of the laser beam is λ and the complex refractive index of the substrate is the actual one. Λ / (10 · n) or more and λ /
(2 · n), and the side wall portion between the groove portion and the flat portion of the land portion is at an angle of 20 ° with respect to the groove portion plane.
An optical information recording medium characterized by forming an angle of 70 ° or more and 70 ° or less. 8. The method for manufacturing an optical information recording medium according to claim 2, wherein at least one of the first dielectric layer, the second dielectric layer, and the reflective layer is formed. Forming a layer by performing sputtering with the substrate facing a target material, and forming the layer by performing sputtering while moving the substrate with respect to the target material when forming the recording layer. A method for producing an optical information recording medium. 9. The method for manufacturing an optical information recording medium according to claim 1, wherein two or more concentric plasma discharge erosions are formed on a target material, and the recording is performed by magnetron sputtering. A method for producing an optical information recording layer, comprising forming a layer. 10. The method for manufacturing an optical information recording medium according to claim 1, wherein at least two or more target materials are used when forming the recording layer. A method for manufacturing an optical information recording medium, comprising: disposing a shielding plate between the substrates. 11. The method for manufacturing an optical information recording medium according to claim 1, wherein a pressure in a vacuum chamber at the time of forming the recording layer is equal to the pressure of the first dielectric layer and the pressure of the second dielectric layer. A pressure higher than a pressure in a vacuum chamber when forming at least one of the dielectric layer and the reflective layer.