JP2002208182A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phase transition type optical recording medium having high reliability, wherein high density and high linear speed recording is possible and characteristics are not deteriorated even if the recording is repetitively performed. SOLUTION: The optical recording medium having a phase transition type recording layer utilizing reversible phase transition between an amorphous phase and a crystal phase by light irradiation and a transparent substrate, a light incident face on the side of the transparent substrate or on the side opposite thereto and a protective layer and the like laminated on the transparent substrate is characterized in that a dielectric protective layer is a mixture consisting of ZnS and SiO2 and a second protective layer is a mixture of SiC added with Al2O3 or AlN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly, to a method of irradiating an optical recording medium with a light beam.
The present invention relates to a phase-change type optical recording medium capable of causing a photochemical change in a recording layer material, recording and reproducing information, and rewritable.

[0002]

2. Description of the Related Art In an optical recording medium capable of recording, reproducing and erasing information by irradiating a laser beam, high density, large capacity and high speed recording and reproduction are always required.
Regarding the capacity, a rewritable phase-change recording medium has a capacity of 4.7 GB with a CD size of 120 mm in diameter. Larger capacity means shorter recording wavelength,
Due to the high NA of the objective lens, theoretically 15G on one side
B or better is said to be achievable. Today, the performance of blue LDs is rapidly advancing as a short-wavelength light source, and a laser with a high output of 400 nm can be used.

[0003] Under such circumstances, it is inevitable that the capacity and density of the phase change recording medium will further increase in the future. However, a high-speed technique for recording and reproducing at a high linear velocity requires improvement of not only a phase change recording medium but also a recording and reproducing technique. In the medium, at present, 3.5 corresponding to the DVD linear velocity is used.
There is a demand for recording at a linear velocity of 10 m / s or more. This is because the phase change recording medium has expanded from the use of a medium for external storage of a computer to the use of a video, and the start of digital broadcasting and the like, it is more necessary today to be able to transfer a large amount of image data at high speed.
In order to perform high-speed recording while maintaining a high recording density, recording and reproducing techniques are required, and at the same time, it is necessary to optimize the material of the phase-change recording layer and the medium configuration.

To meet such demands, a recording / reproducing linear velocity of 3.5 m has been hitherto used by using a recording layer containing Ag, In, Sb, and Te as main constituent elements as a phase change material.
/ S, and a rewritable medium with a capacity of 4.7 GB are at a practical level. However, it cannot be said that the structure is sufficient to satisfy the characteristics while ensuring the reliability including the high number of repetitive recordings and the data storage, and it is necessary to study the medium structure and the medium constituent material more.

[0005] on a transparent substrate, a dielectric protective layer made of _{ZnS · SiO 2, Ag, In} , Sb, recording layer whose main elements of Te, dielectric protective layer further composed of ZnS · SiO _2, consisting of Al alloy In the conventional configuration of a reflective layer, the characteristics when recording at a high linear velocity and at a high density cannot be said to be sufficient. When Ag having higher thermal conductivity than Al alloy is used in order to obtain sufficient properties, there is a problem in that it reacts with S in the protective layer under high temperature and high humidity to form sulfide and deteriorate.

Further, the dielectric protection layer is formed of ZnS.SiO._Two
AlN, SiO with high melting point and high thermal conductivity_Two,
Nitride, carbide, oxidation such as SiN, TaOx, InOx
Is sufficient even when replacing with
Could not be said. Therefore, this application or dielectric
The protective layer has two layers, and the recording layer has ZnS.SiO. _Two, Anti
Thermal conductivity is ZnS.SiO on the emissive layer side_TwoHigher and higher melting point
And a reflective layer and ZnS / SiO_TwoAnd thermal expansion coefficient difference
By using materials such as small SiC and MgO,
A medium having a high number of repeated recordings is provided (Japanese Patent Laid-Open No. 11-8
No. 9341). However, recording at higher linear velocity
In order to obtain a medium with excellent return recording characteristics and storage characteristics,
It was necessary to consider the protective layer material and the recording layer material.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical recording medium which solves such a problem and improves repetitive recording characteristics and storage reliability when recording at a high linear velocity. It is an issue.

[0008]

Means for Solving the Problems The inventors of the present invention have focused on a protective layer constituting an optical recording medium to solve the above problems, and as a result, have completed the present invention. .

That is, according to the present invention, first, there is provided a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, and the light incident surface is a transparent substrate. And an optical recording medium in which a dielectric protective layer, a recording layer, a dielectric protective layer, a second protective layer, and a reflective heat dissipation layer are laminated in this order on the transparent substrate, wherein the dielectric protective layer is composed of ZnS and SiO2.
₂ wherein the second protective layer comprises Al ₂
It is a mixture to which O ₃ or AlN is added, and the amount X
(Mol%) is represented by the following formula (1): 0 <X <15 (1) An optical recording medium is provided.
In the first invention, the thickness of the second protective layer is 2 to 15
nm optical recording media.

According to the present invention, secondly, there is provided a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, and a light incident surface on the transparent substrate side. In an optical recording medium in which a dielectric protective layer, a recording layer, a second protective layer, and a reflective heat dissipation layer are laminated in this order on the transparent substrate, the second protective layer is formed by the above formula (1) (where X is the same as above). An optical recording medium characterized by being a material represented by the following formula:

According to the present invention, thirdly, there is provided a phase change recording layer and a transparent substrate utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a light incident surface is opposite to the transparent substrate. And an optical recording medium in which a reflective heat dissipation layer, a second protective layer, a recording layer, and a dielectric protective layer are laminated in that order on the transparent substrate, wherein the second protective layer has the above formula (1) (where X is The optical recording medium is a material represented by the following formula:

According to the present invention, fourthly, there is provided a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, and the light incident surface is opposite to the transparent substrate. In the optical recording medium in which a reflective heat dissipation layer, a second protective layer, a dielectric protective layer, a recording layer, and a dielectric protective layer are laminated in this order on the transparent substrate, the second protective layer is defined by the above formula (1). (X is the same as described above). In the first to fourth inventions,
An optical recording medium in which the reflective heat radiation layer is made of Ag, Au or an alloy thereof, wherein the recording layer is a phase change recording layer having Sb and Te as constituent elements and a crystalline phase having a NaCl type crystal structure. A recording medium is included, and the phase-change recording layer includes A
The optical recording medium includes two or more elements selected from g, In, and Ge.

Fifth, according to the present invention, there is provided a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, and a light incident surface on the transparent substrate side. In an optical recording medium in which a dielectric protective layer, a recording layer, a dielectric protective layer, a second protective layer, and a reflective heat dissipation layer are laminated in this order on the transparent substrate, the dielectric protective layer is made of ZnS and SiO _2. The second protective layer is a mixture in which Cr is added to SiC, and the added amount X (atomic%) is represented by the following formula (2): 0 <X <10 (2) An optical recording medium is provided.
In the fifth invention, the thickness of the second protective layer is 2 to 15
nm optical recording media.

According to the present invention, sixthly, there is provided a phase-change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, and a light incident surface on the transparent substrate side. And an optical recording medium in which a dielectric protective layer, a recording layer, a second protective layer, and a reflective heat dissipation layer are laminated in this order on the transparent substrate.
An optical recording medium is provided, wherein the protective layer is a material represented by the above formula (2) (X is the same as described above).

According to the present invention, seventhly, there is provided a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, and a light incident surface is opposite to the transparent substrate. And an optical recording medium in which a reflective heat dissipation layer, a second protective layer, a recording layer, and a dielectric protective layer are laminated in that order on the transparent substrate, wherein the second protective layer has the above formula (2) (where X is The optical recording medium is a material represented by the following formula:

Eighth, according to the present invention, there is provided a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate, wherein the light incident surface is a transparent substrate. In the optical recording medium laminated on the transparent substrate in the order of the reflective heat dissipation layer, the second protective layer, the dielectric protective layer, the recording layer, and the dielectric protective layer, the second protective layer has the above formula ( 2) An optical recording medium is provided, which is a material represented by (X is the same as described above). The fifth to eighth inventions include an optical recording medium in which the reflective heat radiation layer is made of Ag, Au or an alloy thereof, wherein the recording layer contains Sb and Te as constituent elements, and the crystal phase is a NaCl type crystal. An optical recording medium which is a phase change recording layer having a structure, wherein the phase change recording layer has A
The optical recording medium includes two or more elements selected from g, In, and Ge.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a phase change type optical recording medium which has sufficient medium characteristics at high linear velocity and high density recording, especially excellent storage reliability after repeated recording, initial and after repeated recording. Things. The optical recording wavelength is 660 to 400 nm,
The NA of the objective lens is 0.6 or more, and the incident light is incident on the surface without the recording layer, the protective layer, and the reflective layer, and when incident from the side with the recording layer, the protective layer, and the reflective layer Apply. As a substrate to be used, a typical polycarbonate substrate is used.

The dielectric protective layer is composed of ZnS and SiO ₂ and has a mixing ratio of ZnS: SiO ₂ = 50: 50 to 85:15.
(Molar ratio). Film thickness is 25-25
0 nm, preferably 45-90 nm.

The refractive index is 1.5 or more as in the case of the substrate, and usually 2.0 to 2.2 is used. Therefore, the lower protective layer may be another transparent oxide, nitride, or carbide having a refractive index of 2.0 to 2.2. Further, two or more lower protective layers may be laminated.

The recording layer has Sb and Te as main constituent elements, and the crystal state before or after recording is NaCl.
A phase-change recording material having a basic crystal structure as a basic structure is used.
By adding at least two kinds of Ag, In, and Ge elements to this recording layer, at a higher recording linear velocity,
It becomes a recording material having excellent recording / reproducing characteristics and reliability.

The optimum composition range of these elements is XαSbβ
When Te1-α-β and X are Ag, In, and Ge, the respective element ratios (atomic%) are 0 <α <15 55 <β <80. X is preferably three elements of Ag, In, and Ge, and Ge is preferably in a range of 0 to 5 atomic%. Even in the phase change recording material having such a composition range, the crystal phase is N
It has an aCl type structure.

The Ag element stabilizes the amorphous phase, and In,
Ge improves the storage reliability, but the number of repetitive recordings,
If the amount of In and Ge is too large to improve the number of times of repeated reproduction, excellent characteristics will not be obtained. With this phase change recording material, the recording linear velocity can correspond to a high linear velocity of 10 to 15 m / s.

The recording wavelength and reproduction wavelength used in the present invention are as follows:
400-680 nm, NA of the objective lens is 0.6-
Use up to 0.85. The reflective heat dissipation layer uses Al, Ag or an alloy thereof, or Au. It is preferable to use a metal or an alloy having higher thermal conductivity than the protective layer and higher thermal conductivity, and it is preferable that the metal or alloy does not deteriorate at high temperature and high humidity. Au
Since Al is expensive and production cost increases, Al, Ag or an alloy thereof is preferable. The film thickness is 5
It is preferably from 0 to 200 nm. These dielectric protective layer, recording layer,
In order to obtain a recording medium having a high number of repetitions at a higher linear velocity recording and a high storage reliability by using a reflective heat radiation layer material, it is necessary to study a layer structure and a material.

First, the case where the light incident direction is from the transparent substrate side will be described. The first layer configuration is such that Z
A protective layer of nS.SiO ₂ (ZnS: SiO ₂ = 80: 20), a recording layer, a ZnSSiO ₂ protective layer, a second dielectric protective layer, and a reflective heat dissipation layer are laminated in this order, and thereafter, ultraviolet curing as an environmental protective layer This is a case where a mold resin is provided. The recording layer is A
gInSbTe, AgInGeSbTe, GeInSb
Te is used. The second protective layer is made of SiC.Al ₂ O ₃ or S
iC.AlN is used. In a bulk sintered body, SiC has a lower thermal conductivity than a metal material used for the reflective heat dissipation layer, but has a thermal conductivity of 2 W / mK or more. Since the specific heat is smaller than that of ZnS · SiO _{2, the} temperature rise due to the heat of the film is low, and it is suitable for the protective layer material. Further, the material is excellent in that the coefficient of thermal expansion is small and the thermal deformation is small.

[0025] This material, by adding Al ₂ O _3, AlN, become more dense film, heat dissipation good, yet even in hot and humid environment, it is possible to ensure the protection . However, although SiC is hard and hard to deform, as in the case of the present invention, the transparent substrate used for DVD is a 0.6 mm thick transparent substrate, and another dummy substrate without a film is bonded. It causes trouble when used. Even if a large warp is generated on the substrate with the film, the warp can be reduced, but when the stress is relaxed due to environmental conditions, the interface of the second protective layer is hard and is not easily deformed. Film peeling from the heat radiation layer occurs. In particular, Al ₂ O ₃ added is effective, SiO ₂
But it works. However, the addition amount is 2 to 1 in the case of Al ₂ O ₃ so as not to impair the inherent characteristics of SiC.
0 mol% and AlN are preferably 3 to 10 mol%. Further, the SiC film is excellent from the viewpoint of production,
Sputtering can be performed by a power supply, and the film formation time can be shortened. In this case, if Al ₂ O ₃ is added too much, the electric conductivity is deteriorated, and thus the amount of Al ₂ O ₃ is limited as described above. Further, by adding Al ₂ O ₃ and AlN to a target material when a film is formed by a sputtering method, there is an advantage that the target density is improved.

For the ZnS.SiO ₂ protective layer and the reflective heat dissipation layer,
In the case of using Ag or an Ag alloy, by sandwiching the second protective layer therebetween, the reaction between Ag and S of ZnS is stopped, and at the same time, the modulation degree is increased in the case of high linear velocity recording, and the recording power margin is increased. Is something that is wide. The preferred thickness range of the second protective layer is 14 to 10 nm.
It is.

The second configuration is a case where a dielectric protective layer, a recording layer, a second protective layer, and a reflective heat dissipation layer are laminated on a substrate in that order. Alternatively, a dielectric protection layer, a recording layer, a second protection layer, a dielectric protection layer, a second protection layer, and a reflective heat dissipation layer may be laminated in that order. Laminating the SiC mixture immediately above the recording layer is more effective as the recording linear velocity increases. When the recording linear velocity is increased, when the recording mark is in an amorphous phase, by using a material having a higher thermal conductivity together with the reflective heat dissipation layer, the quenching condition is satisfied, so that the mark can be easily formed. However, since crystallization hardly occurs, the anti-oblique ratio decreases and the number of repeated overwrites decreases. In this case, the use of the SiC mixture has a function of promoting the formation of a crystal phase. The second protective layer is made of Si
Replacement with an oxide such as O _{2 is} undesirable because it has the opposite effect. Therefore, in this case, the additive Al ₂
The amount of O ₃ is preferably 1 to 5 mol%. on the other hand,
Also in AlN, it is preferable to be 1 to 5 mol%.

Also in the case of nitride, there is a tendency that it is difficult to form a crystal phase. In this case, if the thickness of the second protective layer is too large, the recording sensitivity is reduced. next,
A configuration in the case where the light incident direction is opposite to the transparent substrate will be described. The first configuration is a configuration in which a reflective heat radiation layer, a second protective layer, a recording layer, a dielectric protective layer, and a surface protective coat layer are formed on a transparent substrate. In the case of this configuration, the objective lens NA
Is applied when it is as high as 0.6 to 0.85.

The wavelength is from 400 to 680 nm. The thickness of the protective coat layer is 0.1 mm or less, and the thickness of the substrate to be used is 1.1 to 1.2 mm, and is not bonded to the dummy substrate. Alternatively, the wavelength is 400 nm
In the case of NA of 0.65, the thickness of the transparent substrate is
It is about 0.6 mm, a reflective heat dissipation layer, a second protective layer, a recording layer, and a dielectric protective layer are laminated on the substrate in that order, and finally, an ultraviolet-curable resin is applied, and 0.6 mm without a film is formed. A thick dummy base may be attached to form a medium having a thickness of about 1.2 mm.

In this configuration, in order to cope with a high NA,
The reflective heat radiation layer is preferably made of a material having a higher thermal conductivity than Al, such as Ag or Au. Since the energy density of incident light increases due to the increase in NA, it is necessary to design heat dissipation. If the thickness of each layer is increased by shortening the wavelength of the incident light, the absorption increases and the reflectance decreases.

The thickness of the second protective layer is 2 to 6 nm, the thickness of the recording layer is 5 to 15 nm, and the thickness of the protective layer on the light incident surface side is 5 to 5 nm.
It is preferably set to 0 nm. In this configuration, when Ag or an Ag-rich alloy is used for the reflective heat dissipation layer and ZnS · SiO ₂ is used for the dielectric protection layer, as described above, in order to prevent the formation of sulfide, It is important to provide two protective layers. Another advantage is that a decrease in the number of times of repetitive recording can be suppressed even at a high linear velocity.

The second configuration is a configuration in which a reflective heat radiation layer, a second protective layer, a dielectric protective layer, a recording layer, a dielectric protective layer, and a protective coat layer are formed on a transparent substrate. Also in this case, the effect of the second protective layer can suppress the number of repetitive recordings and the decrease in reflectance after repeated recording. Recording wavelength is 40
In the case of 0 nm, the dielectric protection layer on the substrate side may not be formed. The substrate used for the recording medium is provided with grooves at regular intervals. The interval (pitch) between adjacent grooves is
0.3 to 0.75 μm. Groove depth is 25-50n
m. The shorter the recording wavelength, the narrower the pitch.

In order to perform high-speed, high-density recording with excellent recording / reproducing characteristics using the present recording medium, it is necessary to make sure that the emission pulse of the laser beam applied to the recording medium is equal to or less than the bias power of the recording, erasing, and reproducing power. By controlling at the level. The reason why the bias power is set to be equal to or less than the reproducing power is to facilitate formation of an amorphous phase (mark). This pulse is composed of a leading pulse (1 pulse), a plurality of pulse trains, and a cooling pulse (1 pulse), which sharpens the edge portion of the recording mark, and also corrects the recording position and the length of the recording mark. Is necessary for The recording frequency is
The recording power is about 15 mW at the maximum at about 26 to 80 MHz. The recording / reproducing linear velocity is CLV or CAV, and the linear velocity is 3.5 to 10 m / s. In the present invention, 6.
An example shows a case where recording was performed in the range of 5 to 8.5 m / s.

[0034]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention.

[Examples 1 to 4] When light is incident from the substrate side, the groove pitch is 0.74 μm and the groove width is 0.3 μm.
m, a groove depth of 35 nm, and a thickness of 0.6 mm made of a polycarbonate substrate, on which layers were laminated by a sputtering method. The substrate side protective layer is ZnS: SiO ₂ = 8.
0:20 (mol%) was used, and the film thickness was 75 nm.
Recording layer is _{Ag 1.0 In 5.5 Sb 69.0 Te 24.5} , Ag 1.0 I
An n _4.0 Sb ₇₀ Te _23.0 Ge _2.0 composition was used. The thickness of the recording layer was set to 18 nm. Next, ZnS: SiO ₂ = 80:
20 protective layers were 15 nm thick. The ratio of both SiC: Al ₂ O ₃ and SiC: AlN is 9
7: 3, the film thickness was 5 nm. Next, the reflection layer is made of A
The thickness was 120 nm using a gPdCu alloy. Further, an ultraviolet curing resin was applied to form an environmental protection layer. Finally, the optical recording medium was bonded to a substrate without a film to have a thickness of 1.2 mm. After initialization using a large-diameter LD under predetermined conditions, the recording layer was crystallized. For recording and reproduction, recording was performed in a groove at a recording linear velocity of 8.5 m / s using a pickup head having a wavelength of 658 nm and an objective lens NA of 0.65. Recording was performed so that the recording linear density was 0.26 μm / bit. The modulation method of the recording data is (8, 16) modulation, the recording power is 13 mW, the erasing power is 7 mW, and the bias power is 0.2.
5 mW. The reproduction conditions are the same as the wavelength and NA used for recording at a linear velocity of 3.5 m / s. Jitter 9% or less, the number of repetitive recordings and the initial recording mark 80 ° C,
"〇" when the amount of jitter increase after 300 hours in an 85% RH environment was 2% or less, and "◎" when there was no change.
And Table 1 shows the results. In the comparative example, Zn
This is a case where S · SiO ₂ , a recording layer, ZnS · SiO ₂ , and an AlTi alloy are stacked.

[Examples 5 to 8] The substrates, recording conditions, and measurement conditions are the same as in Examples 1 to 4. The layer structure of the medium is such that ZnS: SiO ₂ = 80: 20 (mol%) on the substrate.
And the film thickness was set to 75 nm. The recording layer is Ag _1.0 I
n _5.5 Sb _69.0 Te _24.5 , Ag _1.0 In _4.0 Sb ₇₀ Te
_{A 23.0} Ge _2.0 composition was used. The thickness of the recording layer was set to 18 nm. The ratio of both SiC: Al ₂ O ₃ and SiC: AlN is 97:
As 3, the film thickness was 10 nm. Next, the reflection layer is made of A
The thickness was 120 nm using a gPd alloy. Jitter 9
% Or less of the number of repetitive recordings and the mark of the first recording
The case where the amount of increase in jitter after 300 hours under 0 ° C. and 5% RH environment was 2% or less was “〇”, and the case where there was no change was “◎”. Table 2 shows the results.

[Embodiments 9 to 12] AgPd alloy reflective heat dissipation layer 120 n on a polycarbonate substrate having a substrate thickness of 0.6 mm, a groove depth of 45 nm, and a track pitch of 0.40 μm.
m, 9 n of SiC: Al ₂ O ₃ and SiC: AlN protective layers
m, Ag _2.0 In _4.5 Sb _65.0 Te _28.5 , Ag _3.0 In _3.0
Sb ₆₆ Te _25.0 Ge _3.0 The recording layer of each composition was 10 nm, Z
The nS.SiO ₂ (ZnS: SiO ₂ = 80: 20) protective layer was set to 45 nm, and a dummy substrate was bonded thereon with an ultraviolet curable resin. The recording wavelength was 405 nm, the NA of the objective lens was 0.65, and the recording / reproducing linear velocity was 7 m / s. With a recording linear density of 0.18 μm,
Recording was performed at a recording power of 10 mW. Jitter 11% or less, the number of repetitive recordings and the initial recording mark at 80 ° C, 8
The case where the amount of increase in jitter after 300 hours in a 5% RH environment was 2% or less was evaluated as “〇”, and the case where there was no change was evaluated as “◎”. Table 3 shows the results.

[Examples 13 to 16] The substrates, recording conditions and measurement conditions are the same as in Examples 9 to 12. AgPd alloy reflective heat dissipation layer 120 nm on substrate, SiC: Al
₂ O ₃ and SiC: AlN protective layer of 4 nm, ZnS · Si
An O ₂ (ZnS: SiO ₂ = 80: 20) protective layer of 8 nm;
Ag _2.0 In _4.5 Sb _69.0 Te _28.5 , Ag _3.0 In _3.0 Sb
₆₆ Te _{25 .0} Ge _3.0 10nm recording layer of each composition, ZnS
4 SiO ₂ (ZnS: SiO ₂ = 80: 20) protective layers
The thickness was set to 5 nm, and a dummy substrate was bonded thereon with an ultraviolet curable resin. "〇" indicates that the jitter increase after 300 hours under 80 [deg.] C. and 85% RH environment for the number of repetitive recordings with jitter of 11% or less and 80 [deg.] C. and 85% RH is 2% or less, and "[Delta]" when there is no change And Table 4 shows the results.

[Embodiments 17 to 20] When light is incident from the substrate side, the groove pitch is 0.74 μm, and the groove width is 0.1 mm.
Using a polycarbonate substrate having a thickness of 3 μm, a groove depth of 35 nm, and a thickness of 0.6 mm, each layer was laminated thereon by a sputtering method. The substrate side protective layer is made of ZnS: SiO ₂
= 80: 20 (mol%), and the film thickness was 75 nm. Recording _{layer, Ag 1.0 In 5.5 Sb 69.0 Te} 24.5, Ag
_{A 1.0} In _4.0 Sb ₇₀ Te _23.0 Ge _2.0 composition was used. The thickness of the recording layer was set to 18 nm. Next, ZnS: SiO ₂ =
The 80:20 protective layer was 15 nm thick. The second protective layer is SiC: Cr = 97: 3, 95: 5 and 5 nm.
. Next, the reflective layer was made of Ag ₉₅ Pd ₃ Ni ₂ alloy and had a thickness of 120 nm. Further, an ultraviolet curing resin was applied to form an environmental protection layer. Finally, the recording medium was attached to a substrate without a film to have a thickness of 1.2 mm. Large diameter L
Using D, the recording layer was crystallized after initialization under predetermined conditions. For recording and reproduction, wavelength 658 nm, objective lens NA 0.6
And a recording linear velocity of 8.5 m /
Recorded in the groove in s. Recording linear density of 0.26 μm / bi
t was recorded. The modulation method of the recording data is
(8, 16) modulation, recording power was 13 mW, erasing power was 7 mW, and bias power was 0.5 mW. The reproduction conditions were the wavelength used for recording at a linear velocity of 3.5 m / s, NA
Is the same as "〇" indicates that the jitter increase after 300 hours under 80 [deg.] C. and 85% RH environment of the mark of the initial recording is 1% or less, and "◎" indicates no change. , The case where it exceeded 1% was regarded as “△”. Table 5 shows the results. In the comparative example, ZnSSiO ₂ , a recording layer, ZnS · SiO ₂ , Al
The case where the Ti alloy is laminated and the case where the second protective layer SiC is provided under the reflective layer and the reflective layer is an Ag alloy.

[Examples 21 to 24] The substrates, recording conditions, and measurement conditions are the same as in Examples 17 to 20. The layer structure of the medium was such that ZnS: SiO ₂ = 80: 20 (mol%) was used on the substrate and the film thickness was 75 nm. The recording layer is A
_{g 1.0 In 5.5 Sb 69.0 Te 24.5} , Ag 1.0 In 4.0 Sb 70
A Te _23.0 Ge _2.0 composition was used. 18n thick recording layer
m. SiC: Cr = 97: 3,9 for the second protective layer
The ratio was 5: 5, and the film thickness was 10 nm. Next, the reflective layer was made of Ag ₉₅ Pd ₃ Ni ₂ alloy and had a thickness of 120 nm. The jitter is 10% or less. The number of repetitive recordings and the initial recording marks are 30% at 80 ° C and 85% RH.
"〇" indicates that the jitter increase after 0 hours is 1% or less,
"◎" indicates no change and "△" indicates a value exceeding 1%. Table 6 shows the results.

[Examples 25 to 28] A substrate thickness of 0.6 mm,
On a polycarbonate substrate having a groove depth of 45 nm and a track pitch of 0.40 μm, an Ag ₉₆ Cu ₂ Ni ₁ alloy reflective heat dissipation layer of 120 nm and a second protective layer of SiC: Cr = 97: 3 were used.
9 nm as 95: 5, Ag _2.0 In _4.5 Sb _65.0 Te
_{28.5, Ag 3.0 In 3.0 Sb 66} Te 25.0 Ge 3.0 10nm recording layer of each _{composition, ZnS · SiO 2 (ZnS:} SiO 2
= 80: 20) The protective layer was set to 45 nm, and a dummy substrate was bonded thereon with an ultraviolet curable resin. An optical head having a recording wavelength of 405 nm and an NA of an objective lens of 0.65 was used, and the recording / reproducing linear velocity was 7 m / s. Recording was performed with a recording linear density of 0.18 μm and a recording power of 10 mW. “〇” indicates that the jitter increase after 300 hours under 80 ° C. and 85% RH environment of the mark of the initial recording is 1% or less, and “◎” indicates that there is no change. The case where it exceeded 1% was regarded as “△”.
Table 7 shows the results. As a comparative example, there are a case where an AlTi alloy, ZnSSiO ₂ , a recording layer, and a ZnS · SiO ₂ layer are laminated on a substrate in this order, and a case where a second protective layer SiC is provided below the reflective layer and the reflective layer is an Ag alloy.

[Examples 29 to 32] The substrates, recording conditions and measurement conditions are the same as in Examples 25 to 28. Ag ₉₆ Cu ₂ Ni ₁ alloy reflective heat dissipation layer 120 nm on substrate, second
The protective layer is made of SiC: Cr = 97: 3, 95: 5 and has a film thickness of 4 nm, ZnS.SiO ₂ (ZnS: SiO ₂ = 80: 2).
0) The protective layer is 8 nm, Ag _2.0 In _4.5 Sb _65.0 T
_{e 28.5, Ag 3 .0 In 3.0} Sb 66 Te 25.0 Ge 3.0 10nm recording layer of each _{composition, ZnS · SiO 2 (ZnS:} Si
(O ₂ = 80: 20) The protective layer was set to 45 nm, and a dummy substrate was bonded thereon with an ultraviolet curable resin. "〇" indicates that the jitter increase after 300 hours under 80 [deg.] C. and 85% RH environment for the number of repetitive recordings with jitter of 11% or less and 80 [deg.] C. and 85% RH is 2% or less, and "[Delta]" when there is no change. And Table 8 shows the results.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

According to the present invention, there is provided a highly reliable phase-change type optical recording medium capable of recording at a high density and a high linear velocity, and whose characteristics are not degraded even after repeated recording. The contribution to this recording field is extremely large.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) G11B 7/24 538 G11B 7/24 538E B41M 5/26 B41M 5/26 X (72) Inventor Wataru Otani Tokyo 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masato Hariya 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Kazunori Ito Naka, Ota-ku, Tokyo 1-3-6, Magome, Ricoh Co., Ltd. (72) Inventor Nobuaki Onagi 1-3-6, Nakamagome, Ota-ku, Tokyo Tokyo, Japan Ricoh (72) Inventor Takashi Shibaguchi, 1-chome Nakamagome, Ota-ku, Tokyo No. 3-6 Ricoh Co., Ltd. (72) Inventor Hiroko Tashiro 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 2H111 E A03 EA04 EA12 EA23 EA31 FA12 FA14 FA21 FA24 FA25 FA27 FA28 FB05 FB09 FB12 FB17 FB21 FB26 FB30 5D029 JA01 JB47 LA13 LA17 LB01 LB07 LB11

Claims (16)

[Claims] 1. A transparent substrate comprising a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a light incident surface on a transparent substrate side, wherein a dielectric material is provided on the transparent substrate. In an optical recording medium in which a body protection layer, a recording layer, a dielectric protection layer, a second protection layer, and a reflective heat dissipation layer are laminated in this order, the dielectric protection layer is a mixture of ZnS and SiO ₂ , The layer is a mixture of SiC and Al ₂ O ₃ or AlN added, and the added amount X (mol%) is represented by the following formula (1) 0 <X <15 (1) recoding media. 2. The optical recording medium according to claim 1, wherein said second protective layer has a thickness of 2 to 15 nm. 3. A transparent substrate comprising a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, wherein the light incident surface is on the transparent substrate side, and a dielectric is provided on the transparent substrate. In an optical recording medium in which a body protective layer, a recording layer, a second protective layer, and a reflective heat dissipation layer are laminated in that order, the second protective layer is defined by the above formula (1).
(X is the same as described above). 4. A transparent substrate having a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a light incident surface opposite to the transparent substrate. In the optical recording medium in which the reflective heat radiation layer, the second protective layer, the recording layer and the dielectric protective layer are laminated in this order, the second protective layer is represented by the above formula (1) (X is the same as above). An optical recording medium characterized in that it is a material. 5. A transparent substrate comprising a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a light incident surface opposite to the transparent substrate. In the optical recording medium in which a reflective heat dissipation layer, a second protective layer, a dielectric protective layer, a recording layer, and a dielectric protective layer are laminated in that order, the second protective layer is formed by the above formula (1) (where X is the same as above). An optical recording medium characterized by being a material represented by the following: 6. The optical recording medium according to claim 1, wherein said reflective heat radiation layer is made of Ag, Au or an alloy thereof. 7. The optical recording medium according to claim 1, wherein the recording layer is a phase change recording layer having Sb and Te as constituent elements and a crystal phase having a NaCl type crystal structure. 8. The phase change recording layer according to claim 7, wherein
The optical recording medium according to claim 7, wherein two or more elements selected from g, In, and Ge are added. 9. A transparent substrate comprising a phase change recording layer utilizing a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a light incident surface on the transparent substrate side, wherein a dielectric material is provided on the transparent substrate. An optical recording medium in which a body protective layer, a recording layer, a dielectric protective layer, a second protective layer, and a reflective heat dissipation layer are laminated in that order, wherein the dielectric protective layer is a mixture of ZnS and SiO _2; Is a mixture obtained by adding Cr to SiC, and the added amount X (atomic%) is represented by the following formula (2): 0 <X <10 (2). 10. The second protective layer has a thickness of 2 to 15 nm.
The optical recording medium according to claim 9, which is: 11. A phase change recording layer using a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate,
In an optical recording medium in which the light incident surface is on the transparent substrate side and a dielectric protective layer, a recording layer, a second protective layer, and a reflective heat dissipation layer are laminated on the transparent substrate in this order, the second protective layer is defined by the above formula ( 2) An optical recording medium characterized by being a material represented by (X is the same as described above). 12. A phase change recording layer using a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate,
In an optical recording medium in which a light incident surface is on the opposite side of a transparent substrate and a reflective heat radiation layer, a second protective layer, a recording layer, and a dielectric protective layer are laminated on the transparent substrate in this order, An optical recording medium characterized by being a material represented by the formula (2) (X is the same as described above). 13. A phase change recording layer using a reversible phase change between an amorphous phase and a crystalline phase by light irradiation, and a transparent substrate,
In an optical recording medium in which a light incident surface is on the opposite side of a transparent substrate and a reflective heat dissipation layer, a second protective layer, a dielectric protective layer, a recording layer, and a dielectric protective layer are laminated on the transparent substrate in this order, An optical recording medium, wherein the layer is a material represented by the above formula (2) (X is the same as above). 14. The optical recording medium according to claim 9, wherein the reflective heat radiation layer is made of Ag, Au, or an alloy thereof. 15. The optical recording medium according to claim 9, wherein said recording layer is a phase change recording layer having Sb and Te as constituent elements and a crystalline phase having a NaCl-type crystal structure. 16. The phase change recording layer according to claim 16, wherein Ag, In and G
The optical recording medium according to claim 15, wherein two or more elements selected from e are added.