JP2002074739A - Optical recording medium and optical recording device - Google Patents

Abstract

[PROBLEMS] Even when recording is performed at a high linear velocity and a high density, cross erasure is less likely to occur even with a substrate having a good erasing characteristic and a small jitter and a narrow track width. Provided is a rewritable phase-change type optical recording medium and an optical recording apparatus which are hardly degraded in signal quality even when repeatedly irradiated with a laser beam and have good storage durability. An optical recording medium of a phase change type, comprising at least a first dielectric layer, a first boundary layer, a recording layer, a second boundary layer, an absorption correction layer, and a reflection layer in this order on at least a substrate; The first boundary layer and the second boundary layer each have a specific recording layer composition, and each of the first boundary layer and the second boundary layer is a layer containing at least one selected from carbon, carbide, oxide, and nitride as a main component; The layer has a refractive index of 1.0 to 4.0 and an extinction coefficient of 0.
An optical recording medium having a size of 5 or more and 3.0 or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium and an optical recording apparatus capable of recording, erasing and reproducing information by irradiating a laser beam. In particular, the present invention relates to a rewritable phase-change optical recording medium capable of recording an information signal at high speed and high density.

[0002]

2. Description of the Related Art A rewritable phase-change optical recording medium has a recording layer containing tellurium or the like as a main component. At the time of recording, a laser beam pulse focused on the crystalline recording layer is irradiated for a short time.
The recording layer is partially melted. The melted portion is quenched by thermal diffusion and solidified to form an amorphous recording mark. The light reflectance of this recording mark is lower than that of the crystalline state and can be reproduced optically as a recording signal. At the time of erasing, the recording mark is irradiated with a laser beam and heated to a temperature below the melting point of the recording layer and above the crystallization temperature to crystallize the amorphous recording mark and return to the original unrecorded state. . Ge ₂ Sb ₂ is used as a material for the recording layer of these rewritable phase-change optical recording media.
Alloy, such as Te ₅ (N.Yamada et al.Proc.Int.Symp.on O
ptical Memory 1987 p61-66) is known.

[0003] These optical recording media using a Te alloy as a recording layer have a high crystallization speed, and high-speed overwriting with a single circular beam is possible only by modulating the irradiation power. In an optical recording medium using these recording layers, usually, a heat-resistant and light-transmitting dielectric layer is provided on each side of the recording layer to prevent deformation and opening of the recording layer during recording. I'm preventing. Furthermore, a technique is known in which a metal reflective layer such as light-reflective Al is laminated on the dielectric layer opposite to the light beam incident direction to improve the signal contrast at the time of reproduction by an optical interference effect. .

Further, in this rewritable phase-change type optical recording medium, the amplitude of the reproduced signal (contrast) is reduced due to repeated overwriting, jitter characteristics are deteriorated, and burst defects due to peeling or destruction of the protective film are caused. For example, there was a problem in the repeated durability of the disk. Means for improving the repetition durability include, for example, those disclosed in
It is known that an anti-diffusion layer is provided in contact with a recording layer as disclosed in Japanese Patent Application Laid-Open No. 1-115315.

However, with the increase in the linear velocity and the density of the optical recording medium, the conventional optical recording medium has a problem that the erasing characteristics deteriorate. That is, if new overwrite recording is performed on a track on which a signal is already recorded, the shape and formation position of the recording mark are modulated by the signal before overwriting, so that the erasing characteristics deteriorate. As a result, there is a problem that the jitter characteristic is deteriorated as compared with the first recording.

As means for improving the erasing characteristics, a technique has been proposed, as disclosed in Japanese Patent Application Laid-Open No. 5-159360, in which an absorbing layer is provided for absorbing light transmitted through a recording film. However, the absorption layer proposed here, namely Ti,
An absorbing layer made of a metal such as Ni, W, Mo, V, Nb, Cr, and Fe is insufficient as a means for improving erasing characteristics.

[0007] Also, due to the increase in linear velocity and density,
There has been a problem that the size of the recording mark is reduced, thereby lowering the signal contrast and deteriorating the jitter.

Further, in the conventional optical recording medium, when the recorded disk is left for a long period of time, the recorded mark may be lost. Further, when overwriting is performed after leaving the optical recording medium on which the signal is recorded for a long time, the jitter characteristic may be significantly deteriorated as compared with the case where overwriting is immediately performed. For this reason, there was a problem in the storage durability of the optical recording medium.

Further, when the track width is narrowed to increase the density, the laser beam sticks out to the adjacent track to affect the recording mark of the adjacent track, and the phenomenon of deteriorating the jitter, that is, the cross erase, is also a serious problem. is there. Especially the laser beam diameter d on the recording surface
On the other hand, when the track width is 0.7 × d or less (d is a laser beam diameter on the recording surface), this problem becomes more serious.

Further, when a laser beam for reproduction is repeatedly irradiated, a part of a recording mark is crystallized, thereby deteriorating the signal quality (so-called reproduction light deterioration). In an optical recording medium in which the crystallization speed is increased in order to cope with high linear velocity recording, problems of cross erasure and reproduction light deterioration are more likely to occur.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide good erasing characteristics and low jitter even when recording is performed at a high linear velocity and high density, hardly cause cross erasure and deterioration of reproduction light, and furthermore preserve the recording. An object of the present invention is to provide a rewritable phase-change type optical recording medium and an optical recording apparatus having good durability.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to record, erase, and reproduce information by irradiating a laser beam, and to record and erase information in an amorphous phase and a crystalline phase. An optical recording medium that is formed by a reversible phase change between at least a first dielectric layer, a first boundary layer, a recording layer, a second boundary layer, an absorption correction layer, and a reflection layer on a substrate in this order. Wherein the composition of the recording layer is represented by the general formula [[(Ge _{1 -k} Sn _k ) _0.5 Te _0.5 ] _x (Sb _0.4 Te _0.6 )
_1-x] with _1-y Sb _y A _z (wherein, A is selected Ge, Sb, from elements belonging from Group 3 to Group 14 of the sixth period of the third period in the periodic table, except for Te X, y,
z and k are relational expressions of the following (1) or (2): 0.5 ≦ x ≦ 0.95, 0 ≦ y ≦ 0.08, 0 <z ≦ 0.2, k = 0 (1) 0.5 ≦ x ≦ 0.95, 0.01 .Ltoreq.y.ltoreq.0.08, z = 0, 0.ltoreq.k.ltoreq.0.5 (2), and the first boundary layer and the second boundary layer are carbon, carbide, oxide and nitride, respectively. Consisting of a layer containing at least one selected from the main components, and
This is achieved by an optical recording medium in which the refractive index of the absorption correction layer is 1.0 or more and 4.0 or less and the extinction coefficient is 0.5 or more and 3.0 or less.

Another object of the present invention is to provide an optical head and an optical recording medium, and irradiate a laser beam from the optical head so that the optical recording medium has a reversible phase between an amorphous phase and a crystalline phase. An optical recording apparatus capable of recording, erasing, and reproducing information by a change, wherein the linear velocity of laser light irradiation is 7.
5 × 10 ⁶ × d (d is the diameter of the laser beam on the recording surface) or more, and the length of the shortest mark among the recording marks recorded by the laser beam in the mark edge method in the laser beam traveling direction is 0. .55 × d or less, the track width of the optical recording medium is 0.7 × d or less,
The present invention is also achieved by an optical recording device in which the optical recording medium is the above-mentioned optical recording medium.

The term "main component" in the present invention means that the component is contained in the layer in an amount of 50% by weight or more.
Further, the component is more preferably contained in the layer in an amount of 80% by weight or more.

The laser beam diameter d is a laser beam whose intensity distribution follows a Gaussian distribution.
/ E refers to become that of the diameter ^2.

One of the causes of the problem that the erasing characteristics are not good is that since the reflectance difference between the amorphous recording mark portion and the crystalline region in the recording layer is large, partial light absorption of the amorphous recording mark is caused. It is conceivable that the amount becomes larger than the amount of light absorption in the crystalline state region. As a result, at the time of recording by the laser beam, the prerecorded recording mark portion is heated faster, so that the overwrite signal is modulated by the signal component before overwriting, which is considered to reduce the erasing rate. .

When the optical recording medium on which a signal is recorded is left for a long period of time, the strength of the reproduced signal and the overwrite jitter are significantly deteriorated. It is conceivable that the recording mark causes a change in state such as the atomic arrangement, or that the dielectric layer and the recording layer react.

Cross erasure and reproduction light deterioration are caused by the fact that the light absorption in the amorphous region of the recording layer is higher than the light absorption in the crystal region, so that the temperature of the recording mark is likely to rise, and The adoption of a recording layer composition with a high crystallization speed to support high linear velocity recording allows recording marks to crystallize even at a low laser power such as the end of a laser beam or reproduction light. Is thought to be the cause.

The present inventors have conducted intensive research and found that
Providing the boundary layer in contact with the recording layer on both sides of the recording layer improves erasing characteristics, improves overwrite jitter, and is also effective in improving storage durability, that is, improving reproduction characteristics and overwrite characteristics after long-term storage. Was found to be.

It has also been found that by finding a large difference in reflectance caused by a phase change and finding a stable recording layer composition of an amorphous phase, it is possible to achieve both good jitter and good storage durability. Further, the composition of the recording layer is:
It has been found that it is also effective in reducing cross erasure and reproduction light deterioration.

Further, an absorption correction layer is provided between the second boundary layer and the reflection layer, and the material of the absorption correction layer is selected so that the optical constants, that is, the refractive index and the extinction coefficient are set to specific values. As a result, the ratio (Ac /
Aa) was larger than before, and the optical design could be designed so that the difference in reflectance between the crystal part and the amorphous part was also large.
As a result, it has been found that high contrast and erasing characteristics can be obtained, and the overwrite jitter is further improved. It has also been found that the provision of the absorption correction layer reduces the amount of light absorbed by the recording mark portion, and reduces the influence of the protruding beam when recording on an adjacent track, thereby reducing cross erasure. Also for the same reason,
It has been found that the durability against reproduction light deterioration is greatly improved.

For the first time, the linear velocity of laser beam irradiation is 7.5 × 10 ⁶ × d (d is the laser beam diameter on the recording surface) or more by the above technique, and recording is performed by a laser beam in a mark edge system. The length of the shortest mark among the recording marks in the laser beam traveling direction is 0.55.
Even when performing high-density recording at a high linear velocity of × d or less, cross erasure hardly occurs even when a substrate having good erasing characteristics and low jitter and a recording track width of 0.7 × d or less is used, A rewritable phase-change type optical recording medium having excellent signal durability and excellent storage durability even when repeatedly irradiated with a laser beam for reproduction can be obtained.

Furthermore, the optical recording medium of the present invention has good repetition durability because the recording layer is sandwiched between boundary layers.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical layer structure of an optical recording medium according to the present invention comprises a first dielectric layer on a transparent substrate,
The first boundary layer, the recording layer, the second boundary layer, the absorption correction layer, and the reflection layer are laminated in this order. However, without being limited to this, it is also possible to provide further layers.
The description will be made in the following order.

The first dielectric layer is provided to prevent the substrate from being damaged by heat during recording and to prevent the recording layer from being deformed and opened by heat. Examples of the material of the first dielectric layer include inorganic compounds such as ZnS, SiO ₂ , silicon nitride, and aluminum oxide. Especially Z
Mixtures of nS and SiO ₂ are preferred. Since this material has a small residual stress, burst deterioration due to repeated overwriting is unlikely to occur. In addition, the mixture of ZnS, SiO _2, and carbon has a smaller residual stress in the film and hardly causes deterioration in recording sensitivity, carrier-to-noise ratio (C / N), erasure rate, and the like even when recording and erasing are repeated. It is particularly preferable from this.

The refractive index of the first dielectric layer is preferably 1.9 or more and 2.4 or less, and the extinction coefficient is preferably 0.1 or less. Thereby, it is possible to design so as to obtain a high reflectance difference by an optical interference effect. The thickness of the first dielectric layer is determined by optical conditions.
nm is preferred. If the thickness is larger than this, cracks and the like may occur. If the thickness is smaller than this, the substrate is easily damaged by heat due to repetition of overwriting, and the repetition characteristics are likely to deteriorate. A particularly preferred range of the thickness is 50 nm or more and 200 nm or less.

In the present invention, it is necessary to provide a boundary layer on both sides of the recording layer in contact with the recording layer. By providing this,
Deterioration of characteristics due to repeated overwriting can be prevented. It is considered that this is because these layers play a role of a barrier layer for preventing diffusion of atoms from the dielectric layer to the recording layer. In addition, the provision of the boundary layer improves the erasing characteristics. It is considered that the crystallization speed is increased by the boundary layer, and the erasing characteristics are improved. Further, by providing a boundary layer, storage durability, that is, reproduction characteristics and overwrite characteristics after long-term storage can be improved. It is presumed that this is because even if the recording layer is left for a long period of time, a change in the state of the recording layer such as an atomic arrangement and a reaction between the dielectric layer and the recording layer can be prevented.

The first boundary layer and the second boundary layer are layers containing at least one selected from carbon, carbide, oxide and nitride as a main component. Here, the main component is 50% by weight.
And more preferably 80% by weight
That is all. As the carbide, oxide, and nitride, carbides, oxides, and nitrides with elements belonging to Groups 3 to 14 of the third to sixth periods of the periodic table can be used. , Si, Sc, Ti, V, Cr, Mn, F
e, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr,
Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, S
n, La, Hf, Ta, W, Re, Ir, Pt, Au,
Carbides, oxides, and nitrides of metals selected from Tl and Pb are preferably used, and more preferably Si, Ge,
Ti, Zr, Ta, Nb, Hf, Al, Y, Cr, W,
Carbides, oxides of metals selected from Zn, In, and Sn;
Nitride is preferably used.

As the material of the first boundary layer, a material containing carbon as a main component is particularly preferable, whereby the long-term storage stability of the recording mark is improved. When a recording layer having good long-term storage stability described later is used, good long-term storage stability can be obtained even with a material mainly containing at least one selected from carbides, oxides, and nitrides. . The material of the second boundary layer may be the same as or different from that of the first boundary layer. From the viewpoint of long-term storage stability, it is preferable that both the first boundary layer and the second boundary layer are layers containing carbon as a main component.

Further, from the viewpoint of improving the durability against repetition, the first
The boundary layer or the second boundary layer is a layer containing nitride as a main component.
Is also preferred. In particular, germanium nitride (GeN_x)
The material whose main component is is that it has excellent adhesion to the recording layer.
And a composition range of 0.8 ≦ x ≦ 1.33 is preferable.
More preferably, Also, by suppressing the oxidation of Ge
Since the effect of improving long-term storage stability can be expected,
Cr, Ti, Mn, Zr, Nb, Mo, Ta, Fe, C
Add at least one selected from o, Ni, Y, La
It is also preferable to add Cr in particular.
No. GeCr_yIn the nitride of 0 ≦ y ≦ 0.5
Preferably in the range of GeCr _0.25Of nitride
Particularly preferred.

The thickness of the boundary layer is such that it is difficult to peel off,
Further, from optical conditions, the thickness is preferably 0.5 nm or more and 10 nm or less. If the thickness exceeds 10 nm, it is easy to peel off from the first dielectric layer and the recording layer. On the other hand, if the thickness is less than 0.5 nm, it is difficult to deposit the film to a uniform thickness, and the effect of providing the boundary layer may not be obtained. If the boundary layer is a layer containing carbon as a main component, it is 0.5 nm or more and 4 nm or more.
The following is particularly preferred from the viewpoint of repetition characteristics and long-term storage stability. The carbon layer is in contact with Ge-S
Since the relatively tightly bound by b-Te recording layer and the ZnS-SiO ₂ dielectric layer and a chemical bond or interaction close to it, it is considered to be less likely to occur, such as peeling at the interface. However, as the thickness of the carbon layer increases, the weak graphite component layer existing near the center in the thickness direction increases in thickness.
It is considered that this portion is easily destroyed at the time of repetition or the like, and a burst error is likely to occur.

When the carbon film is formed by sputtering, the introduced gas may be a mixture of hydrogen as well as a rare gas such as Ar gas. Further, other materials may be mixed, but it is preferable to contain carbon at a ratio of 80 mol% or more in order to obtain good characteristics.

The composition of the recording layer of the present invention needs to be within the range of the following formula. [[(Ge _{1 -k} Sn _k ) _0.5 Te _0.5 ] _x (Sb _0.4 Te _0.6 )
_1-x] with _1-y Sb _y A _z (wherein, A is selected Ge, Sb, from elements belonging from Group 3 to Group 14 of the sixth period of the third period in the periodic table, except for Te Elements, ie, Al, Si, S
c, Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Zn, Ga, Y, Zr, Nb, Mo, Ru, Rh, P
d, Ag, Cd, In, La, Hf, Ta, W, Re,
At least one selected from Ir, Pt, Au, Tl, and Pb, and x, y, z, and k are the following (1) or (2)
Satisfies the relation

0.5 ≦ x ≦ 0.95, 0 ≦ y ≦ 0.08, 0 <z ≦ 0.2, k = 0 (1) 0.5 ≦ x ≦ 0.95, 0.01 ≦ y ≦ 0.08, z = 0, 0 ≦ k ≦ 0.5 (2) When x <0.5, the change in reflectance due to the phase change of the recording layer is small, so that sufficient signal intensity cannot be obtained, and good jitter may not be obtained. In the case of 0.95, the crystallization speed is slowed, so that the erasing characteristics are deteriorated and the overwrite jitter may be deteriorated. If y> 0.08, the initial erasure characteristics may be poor, or the overwrite characteristics after long-term storage may be poor. In the case of z> 0.2, the crystallization speed is slow, so that the erasing characteristics are deteriorated, the overwrite jitter is deteriorated, the repetition characteristics are significantly deteriorated due to phase separation, and the overwrite characteristics after long-term storage are deteriorated. Z = 0 and y
In the case of <0.01, the stability of the amorphous is low, and the reproduction characteristics after long-term storage may be deteriorated.

When z> 0, k = 0. When z = 0, for the purpose of improving the erasing characteristics and the storage durability,
A composition in which part of Ge is replaced with Sn in the range of 0 ≦ k ≦ 0.5 is also preferable.

The use of a recording layer that satisfies the following relational expression is preferable because the stability of the amorphous phase is improved and more favorable long-term storage stability is obtained. ｛(Ge _0.5 Te _0.5 ) _x (Sb _0.4 Te _0.6 ) _1-x ｝ _{1-yz
Sb y A z 0.5 ≦ x ≦} 0.95,0.03 ≦ y ≦ 0.08,0 ≦
z ≦ 0.2 Further, in the above-described recording layer composition range, G in the recording layer
The mole fraction of Sb in the three elements e, Sb and Te is 20
% Or less, that is, 0.4 (1-x) (1-y) + y <0.2 is preferable from the viewpoint of improving erasing characteristics.

The recording layer may contain nitrogen or oxygen, or may contain argon used for sputtering.

The recording layer of the present invention preferably has a thickness of 5 nm or more and 40 nm or less. When the thickness of the recording layer is smaller than the above, the recording characteristics are significantly degraded due to repeated overwriting, and when the recording layer is thicker than the above, the recording layer is likely to move due to repeated overwriting. Jitter worsens. In order to obtain an appropriate cooling rate, the thickness of the recording layer is preferably from 7 nm to
25 nm. The recording layer is preferably thinner from the viewpoint of improving the erasing characteristics by increasing the ratio of the absorptivity between the crystal and the amorphous phase as much as possible. Therefore, the more preferable thickness of the recording layer is 7 nm to 17 nm.

In the present invention, in order to adjust recording sensitivity and the like,
A second dielectric layer may be provided between the second boundary layer and the reflective layer. The material of the second dielectric layer may be the same as the material given as the material of the first dielectric layer, or may be a different material. The thickness is preferably 2 nm or more and 50 nm or less. If the thickness of the second dielectric layer is smaller than the above, defects such as cracks occur, and the durability of the second dielectric layer is undesirably reduced. On the other hand, if the thickness of the second dielectric layer is larger than the above, the cooling degree of the recording layer becomes low, which is not preferable. The thickness of the second dielectric layer has a more direct effect on the cooling of the recording layer, and is preferably 30 nm or less in order to obtain better erasing characteristics and repeated durability. Absorbs light,
Since it can be efficiently used as heat energy for recording and erasing, it is also preferable to form the recording material from a non-transparent material. For example, a mixture of ZnS, SiO ₂ and carbon has a small residual stress in the film, and the recording sensitivity and the carrier to noise ratio (C /
N), which is also preferable because deterioration such as the erasing rate hardly occurs.

In the present invention, it is necessary to provide an absorption correction layer between the second boundary layer or the second dielectric layer and the reflection layer. As described above, in the conventional configuration, the light absorption of the amorphous recording layer is larger than the light absorption of the crystalline recording layer. The light absorption rate can be reduced, the difference in the amount of light absorption from the crystalline state can be reduced, and the difference can be made smaller than the crystalline state. Due to the effect of the correction of the absorption amount, the difference in the temperature rise state during recording between the crystalline part and the amorphous part is reduced, and the shape of the recording mark is disordered, the displacement of the formation position and the like can be reduced. Overwrite jitter can be improved. The absorption correction effect is determined by the thickness and the optical constants (refractive index and extinction coefficient) of each constituent layer, but largely depends on the optical constant of the absorption correction layer. It is necessary that the refractive index and the extinction coefficient of this absorption amount correction layer are appropriate, and the refractive index is 1.0 or more and 4.0 or less, and the extinction coefficient is 0.5 or more and 3.0.
It must be: As a result, it is possible to design so that the reflectance difference due to the phase change is large and the effect of correcting the absorption amount is large. The refractive index and the extinction coefficient are preferably measured at the wavelength of the laser beam for recording or reproducing. Most preferably, 660n
Measure in m.

Preferred materials for the absorption correction layer of the present invention include various alloys and metal compounds, and mixtures thereof, and specifically, for example, silicon, germanium, titanium, zirconium, tungsten, chromium, and molybdenum. And a material mainly containing at least one selected from materials such as a solid solution alloy containing at least one of aluminum, an intermetallic compound, and an oxide, a carbide, and a nitride. In particular, at least one oxide or nitride of aluminum and chromium is preferable because the optical constant can be easily controlled. Especially aluminum oxide,
That is, AlO _{x in} which x is in the range of 0.3 to 0.8 is more preferable because it has an appropriate optical constant as the absorption correction layer. A material in which a metal such as chromium or titanium or its oxide is mixed with aluminum oxide in a range of 10 wt% or less is also preferable because it has an effect of improving corrosion resistance.

The thickness of the absorption correction layer is preferably 1 nm or more from the viewpoint of the effect of correcting the amount of light absorption, and 20 nm from the viewpoint of productivity.
0 nm or less is preferable. The film thickness of the absorption correction layer varies depending on the optical constant of the absorption correction layer, but is not less than 10 nm.
00 nm or less is more preferable.

Examples of the material of the reflective layer include metals and alloys having light reflectivity, and mixtures of metals and metal compounds. Specifically, a metal having a high reflectivity, such as Al, Au, Ag, or Cu, an alloy containing the same as a main component, Al, S
Metal compounds such as nitrides, oxides, and chalcogenides such as i are preferable. Metals such as Al, Au, and Ag, and alloys containing these as main components are particularly preferable because of their high light reflectivity and high thermal conductivity. In particular, an alloy containing Al or Ag as a main component is preferable because the price of the material can be reduced. The thickness of the reflective layer is usually
It is about 10 nm or more and about 300 nm or less. 30 nm because of high recording sensitivity and high reproduction signal strength
It is preferably at least 200 nm.

Next, a method for manufacturing the optical recording medium of the present invention will be described. As a method of forming a first dielectric layer, a boundary layer, a recording layer, a second boundary layer, a second dielectric layer, an absorption correction layer, a reflection layer, and the like on a substrate, a thin film formation method in a vacuum, for example, Examples include a vacuum deposition method, an ion plating method, and a sputtering method. In particular, the sputtering method is preferable because the composition and the film thickness can be easily controlled.
The thickness of the recording layer or the like to be formed can be easily controlled by monitoring the deposited state with a quartz crystal film thickness meter or the like.

After forming the reflective layer, a dielectric layer of ZnS, SiO ₂ , ZnS—SiO ₂ , or the like or a UV-cured layer is formed within a range that does not significantly impair the effects of the present invention. A protective layer such as a resin may be provided as necessary.

Further, the optical recording apparatus of the present invention has an optical head capable of irradiating a laser beam, and irradiates the optical recording medium with the laser beam from the optical head, thereby forming an amorphous phase in the optical recording medium. The information is recorded, erased and reproduced by a reversible phase change between the phase and the crystal phase.

The wavelength of the laser beam is preferably from 645 nm to 660 nm for high density recording. The wavelengths of laser beams for recording, erasing and reproducing information may be the same or different. In addition, the linear velocity of the laser beam irradiation is set at 7.20 per second for high linear velocity recording.
It is preferably at least 5 × 10 ⁶ × d (d is the laser beam diameter on the recording surface).

For high-density recording, the information recording method is as follows.
The mark edge method is preferred. Further, it is preferable that the length of the shortest mark among the recording marks recorded by the mark edge method in the laser light traveling direction is 0.55 × d or less. The track width is preferably 0.7 × d or less.

[0049]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. (Analysis and Measurement Method) The compositions of the reflective layer and the recording layer were confirmed by ICP emission analysis (manufactured by Seiko Instruments Inc.).
The composition of the absorption correction layer was confirmed by Rutherford backscattering analysis. The film thickness during the formation of the recording layer, the dielectric layer, and the reflective layer was monitored with a quartz crystal film thickness meter. The thickness of each layer was measured by observing the cross section with a scanning or transmission electron microscope.

In the optical recording medium formed by sputtering, before recording, the recording layer on the entire surface of the disk was crystallized and initialized with a beam of a semiconductor laser having a wavelength of 830 nm.

The recording characteristics were such that the numerical aperture of the objective lens was 0.6,
Using an optical head having a semiconductor laser wavelength of 660 nm (laser beam diameter 0.95 μm), the linear velocity is 8.2.
The evaluation was performed by performing mark edge recording by the 8-16 modulation method under the condition of m / sec. The recording laser waveform is a general multi-pulse, and a pattern adaptive recording compensation method in which the edge position of the recording pulse is changed according to the length of the recording mark and the length of the space before and after the recording mark is used. The recording power and the erasing power were optimized for each optical recording medium. The reproduction power was 1.0 mW.

The reflectivity was determined from the reproduction signal potential at the mirror section of the optical recording medium.

The erasing characteristics were evaluated as follows. First, the longest recording mark (11T mark) is overwritten on the groove 10 times at a recording frequency of 2.7 MHz, and the shortest recording mark (3T mark,
The length of the laser beam in the traveling direction is 0.42 μm), and the spectrum is obtained under the condition of a bandwidth of 30 kHz with the ratio of the carrier of the shortest recording mark to the carrier of the longest recording mark after overwriting as an effective erasing rate. It was measured by an analyzer.

Next, 10 random patterns are formed in the groove.
After overwriting 0 times, the jitter was measured with a time interval analyzer. Subsequently, random patterns were overwritten on adjacent tracks on both sides 100 times and then erased, and the jitter of the center track was measured again to evaluate the degree of increase in jitter due to cross erasure.

With respect to the durability against the reproduction light deterioration, the recorded track was recorded at a reproduction power of 1.2 mW.
Reproduction was repeated 000 times, and evaluation was made by measuring the change in jitter.

Regarding the repetition durability, 1 was added to the groove.
Evaluation was made by the jitter after the overwriting was performed 100,000 times. Also, the oscilloscope reduces the amplitude of the signal waveform,
The presence or absence of burst defects was also observed.

Regarding the storage durability, recording was performed using an evaluation drive capable of measuring the byte error rate, and after storing in an oven at 80 ° C. or 90 ° C. for performing an acceleration test, signal reproduction characteristics and overwriting were performed. The characteristics were evaluated at the byte error rate. (Example 1) thickness 0.6 mm, diameter 12 cm, 1.23
μm pitch (land width 0.615 μm, groove width 0.
Sputtering was performed while rotating a polycarbonate substrate having a spiral groove of 615 μm) at 40 revolutions per minute. First, the inside of the vacuum vessel was evacuated to 1 × 10 ⁻⁴ Pa.
A ZnS target to which O ₂ was added by 20 mol% was sputtered to form a first dielectric layer (refractive index: 2.1, extinction coefficient: 0) with a thickness of 135 nm on the substrate. Next, a carbon target was sputtered to form a carbon layer of 2 nm as a first boundary layer. Subsequently, an alloy target made of Ge, Sb, and Te is sputtered to a thickness of 10 nm.
The composition Ge _28.6 Sb _17.8 Te _53.6 , that is, ｛(Ge _{0.5
Te 0.5) 0. 579 (Sb 0.4} Te 0.6) 0.421} 0.989 Sb
A recording layer of _0.011 was obtained. Further, as a second boundary layer, a germanium target (GeN) layer formed by sputtering a germanium target with a mixed gas of argon and nitrogen is used.
_1.2 ) was formed to a thickness of 2 nm. Subsequently, the same ZnS—SiO ₂ target as that of the first dielectric layer was sputtered as a second dielectric layer to form a second dielectric layer having a thickness of 26 nm. Further, as an absorption correction layer, an aluminum target was sputtered with a mixed gas of argon and oxygen to form an aluminum oxide layer (AlO _0.41 , refractive index 2.2, extinction coefficient 2.1) of 50 nm. Then, Al _97.5 Cr
_{A 2.5-} nm thick reflective layer was formed by sputtering _2.5 alloy. After removing the disk from the vacuum container, an acrylic UV-curable resin (SD-101 manufactured by Dainippon Ink and Chemicals Co., Ltd.) is spin-coated on the reflective layer, and cured by UV irradiation to form a resin layer having a thickness of 3 μm. Forming
Next, a slow-acting ultraviolet curable resin was applied using a screen printing machine, and after irradiating with ultraviolet rays, two disks produced in the same manner were adhered to obtain an optical recording medium of the present invention.

The reflectance when the recording layer is in a crystalline state;
The difference in reflectance in the amorphous state was 20%, and sufficient contrast was secured. In addition, a wavelength of 660 nm
According to the optical calculation, the ratio (Ac / Aa) of the light absorptivity between the crystalline region and the amorphous region of the recording layer was 1.0, and an absorption amount correction effect was obtained. When the effective erasure rate was measured, it was 2
8 dB, and the erasing characteristics were good. Jitter after overwriting 100 times is 7.7% of window width
And was very good. 7.9% jitter including the effect of cross erasure due to repeated recording on adjacent tracks
Thus, the rise of the jitter value due to the cross erasure was small.
In addition, no reproduction light deterioration was observed. The jitter after overwriting 100,000 times was 9.8%, which was confirmed to be sufficiently small for practical use. The amplitude of the signal hardly changed compared to the amplitude of the signal after overwriting 100 times, and no burst defect was observed. That is, it was found that there was no problem in repeated durability.

Further, recording is performed once on this optical recording medium,
When I measured the byte error rate at that time, it was 1.0 × 1
It was 0 ^-5 . In a state where the humidity was not adjusted such as humidification, the sample was left for 100 hours at 80 ° C. in the recorded state. After that, when the byte error rate of the same portion was measured, it was found that there was almost no change of 1.6 × 10 ^−5, and that the reproduction characteristics after long-term storage were good. Further, when this portion was overwritten once, it was confirmed that the byte error rate was 3.2 × 10 ^-5 and the overwrite characteristics after long-term storage were sufficiently good. Further, the same optical recording medium was left at 90 ° C. and a relative humidity of 80% for 140 hours, but no burst defect due to peeling was observed. That is, it was confirmed that the storage durability was good. (Example 2) As a first boundary layer, a germanium nitride layer (G
eN _1.2 ) An optical recording medium similar to that of Example 1 was formed except that the film was formed to a thickness of 2 nm and evaluated. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. Example 3 The composition of the recording layer was Ge _28.8 Sb _18.8 T
e _52.4, i.e. _{{(Ge 0.5 Te 0.5) 0.} 594 (Sb 0.4
Example 2 _{except that} Te _0.6 ) _{0.406 0.0 0.969} Sb _0.031
An optical recording medium similar to the above was prepared and evaluated. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 4) An optical recording medium similar to that of Example 1 was produced and evaluated except that a carbon layer was formed as a second boundary layer with a thickness of 2 nm.
As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Embodiment 5) GeC is used as the first boundary layer and the second boundary layer.
An optical recording medium similar to that of Example 3 was prepared and evaluated except that a target of r _0.25 was a germanium chromium nitride layer (GeCr _0.25 N _1.2 ) having a thickness of 2 nm formed by sputtering with a mixed gas of argon and nitrogen. As shown in Table 2, the erasure characteristics, jitter, cross erasure, reproduction light deterioration,
It was confirmed that all the repetition durability and storage durability were good. (Example 6) A thickness of 10 nm was produced by sputtering an alloy target composed of Ge, Sn, Sb, and Te.
Composition Ge _22.2 Sn _7.4 Sb _17.1 Te _53.3 , ie
[｛(Ge _0.75 Sn _0.25 ) _0.5 Te _0.5 ] _0.60 (Sb _0.4 T
e _0.6 ) _0.40 ] _0.987 Sb _0.013 An optical recording medium similar to that of Example 1 was prepared and evaluated. As shown in Table 2, the erasure characteristics, jitter, cross erasure, reproduction light deterioration,
It was confirmed that all the repetition durability and storage durability were good. (Example 7) An optical recording medium similar to that of Example 3 was prepared and evaluated except that the first boundary layer and the second boundary layer were formed of an aluminum oxide layer having a thickness of 2 nm formed by sputtering an aluminum oxide target with argon gas. did. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. Example 8 An optical recording medium similar to that of Example 3 was prepared and evaluated, except that the first boundary layer and the second boundary layer were formed of a silicon carbide layer 2 nm formed by sputtering a silicon carbide target with argon gas. did. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. Example 9 The composition of the recording layer was Ge ₃₆ Sb ₁₂ Te ₅₂ , that is, ｛(Ge _0.5 Te _0.5 ) _0.733 (Sb _0.4 T
e _0.6 ) _{0.267 同 様 0.987} Sb _0.013 An optical recording medium similar to that of Example 1 was prepared and evaluated. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. Example 10 The composition of the recording layer was Ge _28.3 Sb _16.9 Te
_53.8 Nb _1, i.e. _{{(Ge 0.5 Te 0. 5)} 0.572 (Sb
_0.4 Te _0.6 ) _0.428 ｝ _0.99 Nb _0.01 An optical recording medium similar to that of Example 1 was prepared and evaluated. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good.

In the recording layer composition, Al, Si, Sc, Ti, V, Cr, Mn, Fe, C
o, Ni, Cu, Zn, Ga, Ge, Y, Zr, Mo,
Ru, Rh, Pd, Ag, Cd, In, Sn, La, H
f, Ta, W, Re, Ir, Pt, Au, Tl or P
Almost the same results were obtained when b was used. (Example 11) A 50 nm-thick aluminum oxide layer (Al) formed by sputtering an aluminum target with a mixed gas of argon and oxygen was used as an absorption correction layer.
An optical recording medium was prepared and evaluated in the same manner as in Example 1 _except that O _0.64 , the refractive index was 2.8, and the extinction coefficient was 1.5).

As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, deterioration of reproduction light, repetition durability and storage durability were good. (Example 12) A 50 nm thick chromium nitride layer (CrN _0.74 , refractive index: 3 nm) formed by sputtering a chromium target with a mixed gas of argon and nitrogen on a chromium target.
2. An optical recording medium similar to that of Example 1 was prepared and evaluated except that the extinction coefficient was 2.3).

As shown in Table 2, it was confirmed that the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were all good. (Example 13) A 50-nm-thick chromium nitride layer (CrN _0.91 , refractive index: 3 nm) formed by sputtering a chromium target with a mixed gas of argon and nitrogen on a chromium target.
5, an optical recording medium similar to that of Example 1 was prepared except that the extinction coefficient was 1.7), and evaluated.

As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 14) An absorption correction layer was formed on an aluminum nitride layer (AlN, refractive index 2.2, extinction coefficient 2.0) having a thickness of 50 nm formed by sputtering an aluminum target with a mixed gas of argon and nitrogen. Other than that, an optical recording medium similar to that of Example 1 was produced and evaluated.

As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 15) As a first boundary layer and a second boundary layer, a germanium nitride layer (Ge) formed by sputtering a germanium target with a mixed gas of argon and nitrogen is used.
An optical recording medium was prepared and evaluated in the same manner as in Example 3 except that N _0.8 ) was formed to a thickness of 2 nm. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 16) GeC was used as the first boundary layer and the second boundary layer.
An optical recording medium similar to that of Example 3 was prepared and evaluated except that a target of r _0.25 was a germanium chromium nitride layer (GeCr _0.25 N _0.8 ) having a thickness of 2 nm formed by sputtering with a mixed gas of argon and nitrogen. As shown in Table 2, the erasure characteristics, jitter, cross erasure, reproduction light deterioration,
It was confirmed that all the repetition durability and storage durability were good. (Example 17) GeC was used as the first boundary layer and the second boundary layer.
except that the r _0.2 Target argon and sputtered germanium nitride chromium layer having a thickness of 2nm which is formed by a mixed gas of nitrogen and (GeCr _0.2 N _1.2) were prepared in the same manner as the optical recording medium of Example 3 was evaluated. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Embodiment 18) GeC is used as the first boundary layer and the second boundary layer.
An optical recording medium similar to that of Example 3 was prepared and evaluated except that the r _0.4 target was a germanium chromium nitride layer (GeCr _0.4 N _1.2 ) having a thickness of 2 nm formed by sputtering with a mixed gas of argon and nitrogen. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. Under the same conditions as Example 19 Example 1, the ZnS-SiO ₂ layer having a thickness of 120nm was formed as the first dielectric layer on a substrate, then the carbon layer was 2nm formed as the first boundary layer,
Subsequently, the thickness is 9 nm, and the composition is Ge ₃₆ Sb ₁₂ Te ₅₂ , that is, {(Ge _0.5 Te _0.5 ) _0.733 (Sb _0.4 Te _0.6 ) _0.267 }.
A recording layer of _0.987 Sb _0.013 was formed, a carbon layer of 2 nm was formed as a second boundary layer, and a ZnS-SiO ₂ layer having a thickness of 35 nm was formed as a second dielectric layer. Further, as an absorption correction layer, an aluminum target is sputtered with a mixed gas of argon and oxygen to form an aluminum oxide layer (AlO _0.41 , refractive index 2.2, extinction coefficient 2.
1) was formed to a thickness of 70 nm. Subsequently, an Al _97.5 Cr _2.5 alloy was sputtered to form a reflective layer having a thickness of 90 nm.

As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 20) A 50-nm-thick chromium nitride layer (CrN _0.74 , refractive index: 3 nm) formed by sputtering a chromium target with a mixed gas of argon and nitrogen on a chromium target.
An optical recording medium similar to that of Example 19 was prepared and evaluated except that the extinction coefficient was 2.3).

As shown in Table 2, the erasing characteristics and jitter
Erasure, cross erasure, reproduction light deterioration,
It was confirmed that all of the durability was good. (Example 21) Under the same conditions as in Example 1, the film thickness was formed on the substrate.
70 nm ZnS-SiO_TwoLayer as first dielectric layer
Then, a carbon layer is formed to a thickness of 2 nm as a first boundary layer.
And a thickness of 12 nm and a composition Ge₃₆Sb₁₂Te₅₂Ie
｛(Ge_0.5Te_0.5)_0.733(Sb_0.4Te_0.6)_0.267｝
_0.987Sb_0.013, And a second boundary layer
A carbon layer is formed to a thickness of 2 nm, and then a second dielectric layer is formed.
15 nm thick ZnS-SiO_TwoA layer was formed. Further
Aluminum target as an absorption correction layer
Acid formed by sputtering with a gas mixture of gon and oxygen
Aluminum oxide layer (AlO_0.64, Refractive index 2.8, extinction
Number 1.5) is provided at 50 nm, followed by Al _97.5Cr_2.5Combination
Sputtering gold to form 90nm thick reflective layer
did.

As shown in Table 2, it was confirmed that the erasure characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were all good. (Example 22) A 50-nm-thick chromium nitride layer (CrN _0.91 , refractive index: 3 nm) formed by sputtering a chromium target with a mixed gas of argon and nitrogen on a chromium target.
5, an optical recording medium similar to that of Example 21 except that the extinction coefficient was 1.7) was produced and evaluated.

As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 23) The composition of the recording layer was Ge ₃₅ Sb ₁₄ Te ₅₁ , that is, ｛(Ge _0.5 Te _0.5 ) _0.733 (Sb _0.4 Te _0.6 ).
_{Example 22 except that 0.267} ｝ _0.967 Sb _0.033 , and that the first and second boundary layers were a germanium target (GeN _1.2 ) with a thickness of 2 nm formed by sputtering a germanium target with a mixed gas of argon and nitrogen. A similar optical recording medium was prepared and evaluated.

As shown in Table 2, it was confirmed that the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were all good. (Example 24) An optical recording medium similar to that of Example 23 was prepared and evaluated except that the first boundary layer and the second boundary layer were formed of an aluminum oxide layer having a thickness of 2 nm formed by sputtering an aluminum oxide target with argon gas. did. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 25) An optical recording medium similar to that of Example 23 was prepared and evaluated, except that the first boundary layer and the second boundary layer were formed of a silicon carbide layer having a thickness of 2 nm formed by sputtering a silicon carbide target with argon gas. did. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. (Example 26) The composition of the recording layer was Ge _36.3 Sb _10.6 Te
_52.1 Nb _1, i.e. _{{(Ge 0.5 Te 0. 5)} 0.733 (Sb
_0.4 Te _0.6 ) An optical recording medium similar to that of Example 22 _{except that 0.267} ｝ _0.99 Nb _0.01 was used was evaluated. As shown in Table 2, it was confirmed that all of the erasing characteristics, jitter, cross erasure, reproduction light deterioration, repetition durability and storage durability were good. Comparative Example 1 An optical recording medium similar to that of Example 1 was prepared and evaluated except that the first boundary layer and the second boundary layer were not provided.
The effective erasing rate was 15 dB, which was significantly inferior to Example 1. As a result, the overwrite jitter also deteriorates,
The jitter at the time of recording was as large as 11.5%. After overwriting 100,000 times, the amplitude of the reproduced signal decreased, the jitter increased to 18%, and problems such as an increase in error rate occurred.

The recording was performed once on this disk, and the byte error rate at that time was measured.
^-5 . In a state where the humidity was not adjusted such as humidification, the sample was left for 100 hours at 80 ° C. in the recorded state. After that, when the byte error rate of the same part was measured, it was 3.9 × 10 ⁻⁵ and there was almost no change. However, when this part was overwritten once, the byte error rate was 4.3 × 10 ^−3. And the overwrite characteristics after long-term storage were remarkably inferior. (Comparative Example 2) An optical recording medium similar to that of Example 1 was prepared and evaluated except that the absorption amount correction layer was not provided. However, the thicknesses of the first dielectric layer, the recording layer, and the second dielectric layer are 160 nm, 12 nm, and 17 n, respectively, so as to be optically optimal.
m.

At the wavelength of 660 nm, the ratio (Ac / Aa) of the light absorptivity between the crystalline region and the amorphous region of the recording layer is 0.1.
8, and the ratio of the light absorptivity was small because the absorption amount correction layer was not provided. The effective erasing rate was 21 dB, which was inferior to Example 1. The jitter after recording 100 times is 8.7%,
The jitter including the effect of cross erasure due to repeated recording on adjacent tracks was 9.7%, and the rise in jitter due to the effect of cross erasure was large. When the track recorded 100 times was repeatedly reproduced 1000 times, the jitter was 13.0%, and deterioration of the reproduction light was observed.

As shown in Table 2, the repetition durability and the storage durability were good. (Comparative Example 3) Light similar to that of Example 1 except that the absorption amount correction layer was a titanium layer (refractive index 2.5, extinction coefficient 3.2) 50 nm formed by sputtering a titanium target with argon gas. A recording medium was prepared and evaluated. Wavelength 660
Example 1 The light absorption ratio (Ac / Aa) at 0.9 nm was 0.9.
It was slightly smaller than. The effective erasure rate is 23dB,
It was slightly inferior to Example 1. The jitter at the time of recording 100 times was 8.8%, and the jitter including the effect of cross erasure due to repeated recording on an adjacent track was 9.8%. That is, the rise in jitter due to the influence of cross erasure was large.

In addition, almost the same results were obtained when Ni, W, Mo, V, Nb, Cr, and Fe were used instead of Ti as the absorption correction layer. Comparative Example 4 The composition of the recording layer was Ge _47.9 Sb _2.5 T
e _49.6, i.e. _{{(Ge 0.5 Te 0.5) 0.9} 7 (Sb 0.4
Example _{0.6 except that} Te _0.6 ) _0.03 ｝ _0.987 Sb _0.013 .
An optical recording medium similar to the above was prepared and evaluated. The effective erasure rate was 13 dB, which was significantly lower than that of Example 1. Therefore, the jitter after recording 100 times was as large as 11.6%. (Comparative Example 5) The composition of the recording layer was Ge _19.7 Sb _25.0 T
e _55.3, i.e. _{{(Ge 0.5 Te 0.5) 0.} 40 (Sb 0.4
Example 1 _{except that} Te _0.6 ) _0.60 ｝ _0.987 Sb _0.013 .
An optical recording medium similar to the above was prepared and evaluated. The effective erasing rate was 25 dB, and the erasing characteristics were good. However, the difference in reflectance between the case where the recording layer is crystalline and the case where the recording layer is amorphous is 1
4%, which is smaller than that of Example 1, and the jitter after overwriting 100 times was as large as 9.8%. Comparative Example 6 The composition of the recording layer was Ge _28.6 Sb _17.1 T
e _54.3, i.e. _{(Ge 0.5 Te 0.5) 0.57 2} (Sb 0.4 T
e _0.6 ) _0.428 , and the same optical recording medium as in Example 1 was prepared and evaluated. As shown in Table 2, the erasure characteristics, jitter, cross erasure, and repetition durability were good.

Recording was performed once on this disk, and the byte error rate at that time was measured to be 1.2 × 10 ^-5 . In a state where the humidity was not adjusted such as humidification, the sample was left for 100 hours at 80 ° C. in the recorded state.
Thereafter, when the byte error rate of the same portion was measured, the error rate was remarkably increased to 1.4 × 10 ^−3, and the reproduction characteristics after long-term storage were inferior. (Comparative Example 7) The composition of the recording layer was Ge _25.7 Sb _25.4 T
e _48.9, i.e. _{{(Ge 0.5 Te 0.5) 0.} 572 (Sb 0.4
An optical recording medium similar to that of Example 1 was prepared and evaluated _{except that} Te _0.6 ) _0.428 ｝ _0.9 Sb _0.1 . Effective erasure rate is 18
dB, which was inferior to Example 1.

Further, recording was performed once on this disk, and the byte error rate at that time was measured.
^-5 . In a state where the humidity was not adjusted such as humidification, the sample was left for 100 hours at 80 ° C. in the recorded state. Thereafter, when the byte error rate of the same portion was measured, it was found that there was almost no change of 3.0 × 10 ^−5, and that the reproduction characteristics after long-term storage were good. However, when this portion was overwritten once, the byte error rate was significantly increased to 3.4 × 10 ⁻³ . That is, the overwrite characteristics after long-term storage were inferior. (Comparative Example 8) The composition of the recording layer was Ge ₂₀ Sb ₁₂ Te ₃₈ N
b _30, i.e. _{{(Ge 0.5 Te 0.5) 0.} 572 (Sb 0.4 T
_{e 0.6) 0.428} 0.7 Nb 0.3} , and the other is to produce a similar optical recording medium as in Example 1 and evaluated. Effective erasure rate is 19d
B, which was inferior to Example 1. The jitter after overwriting 100 times was as large as 10.7%, which was inferior to Example 1. After overwriting 100,000 times, the amplitude of the reproduced signal decreased, the jitter increased to 17%, and problems such as an increase in error rate occurred.

The recording was performed once on this disk, and the byte error rate at that time was measured.
^-5 . In a state where the humidity was not adjusted such as humidification, the sample was left for 100 hours at 80 ° C. in the recorded state. After that, when the byte error rate of the same portion was measured, it was found that there was almost no change of 9.5 × 10 ^−5, and that the reproduction characteristics after long-term storage were good. However, when this portion was overwritten once, the byte error rate was significantly increased to 8.5 × 10 ⁻³ . That is, the overwrite characteristics after long-term storage were inferior. (Comparative Example 9) As an absorption correction layer, an aluminum target was sputtered with an argon / oxygen mixed gas having a composition different from that of Example 1 to form an aluminum oxide layer (AlO
An optical recording medium was manufactured and evaluated in the same manner as in Example 1, except that _0.25 , a refractive index of 2.0, and an extinction coefficient of 3.5) were formed at 50 nm. Light absorption ratio at wavelength 660 nm (Ac / Aa)
Was 0.9, which was slightly smaller than that of Example 1. The effective erasing rate was 21 dB, which was slightly inferior to Example 1. 100
The jitter at the time of recording is 8. for each of the land and groove.
The jitter including the effect of cross erasure by repeated recording on adjacent tracks was 9.3%, and the increase in jitter due to cross erasure was rather large. (Comparative Example 10) As an absorption correction layer, an aluminum target was sputtered with an argon / oxygen mixed gas having a composition different from that of Example 1 to form an aluminum oxide layer (AlO).
An optical recording medium was manufactured and evaluated in the same manner as in Example 1 _except that _0.90 , a refractive index of 2.2, and an extinction coefficient of 0.4) were formed at 50 nm. Light absorption ratio at wavelength 660 nm (Ac / Aa)
Was 0.8, which was smaller than that of Example 1. The effective erasing rate was 18 dB, which was inferior to Example 1. The jitter at the time of recording 100 times was 9.0%, and the jitter including the influence of cross erasure due to repetitive recording on an adjacent track was 10.1%. The increase in jitter due to cross erasure was rather large.

[0077]

[Table 1]

[0078]

[Table 2]

[0079]

According to the optical recording medium of the present invention, even when high-density recording is performed at a high linear velocity, erasing characteristics are good and jitter is small, and cross erasing hardly occurs even when a substrate having a narrow track width is used. In addition, it is possible to provide a rewritable phase-change optical recording medium and an optical recording apparatus that are less likely to deteriorate in signal quality even when repeatedly irradiated with a laser beam for reproduction and that have good storage durability. Furthermore, the optical recording medium of the present invention
Excellent in repeated durability.

[Procedure amendment]

[Submission Date] May 30, 2001 (2001.5.3)
0)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to record, erase, and reproduce information by irradiating a laser beam, and to record and erase information in an amorphous phase and a crystalline phase. An optical recording medium that is formed by a reversible phase change between at least a first dielectric layer, a first boundary layer, a recording layer, a second boundary layer, an absorption correction layer, and a reflection layer on a substrate in this order. Wherein the composition of the recording layer is represented by the general formula [[(Ge _{1 -k} Sn _k ) _0.5 Te _0.5 ] _x (Sb _0.4 Te _0.6 )
_1-x] with _{1-y -z Sb y A z} ( wherein, A is selected Ge, Sb, from elements belonging from Group 3 to Group 14 of the sixth period of the third period in the periodic table, except for Te X, y,
z and k are relational expressions of the following (1) or (2): 0.5 ≦ x ≦ 0.95, 0 ≦ y ≦ 0.08, 0 <z ≦ 0.2, k = 0 (1) 0.5 ≦ x ≦ 0.95, 0.01 .Ltoreq.y.ltoreq.0.08, z = 0, 0.ltoreq.k.ltoreq.0.5 (2), and the first boundary layer and the second boundary layer are carbon, carbide, oxide and nitride, respectively. Consisting of a layer containing at least one selected from the main components, and
This is achieved by an optical recording medium in which the refractive index of the absorption correction layer is 1.0 or more and 4.0 or less and the extinction coefficient is 0.5 or more and 3.0 or less.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

The composition of the recording layer of the present invention needs to be within the range of the following formula. [[(Ge _{1 -k} Sn _k ) _0.5 Te _0.5 ] _x (Sb _0.4 Te _0.6 )
_1-x] with _{1-y -z Sb y A z} ( wherein, A is selected Ge, Sb, from elements belonging from Group 3 to Group 14 of the sixth period of the third period in the periodic table, except for Te Elements, ie, Al, Si, S
c, Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Zn, Ga, Y, Zr, Nb, Mo, Ru, Rh, P
d, Ag, Cd, In, La, Hf, Ta, W, Re,
At least one selected from Ir, Pt, Au, Tl, and Pb, and x, y, z, and k are the following (1) or (2)
Satisfies the relation

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 7/24 538 G11B 7/24 538A 7/006 7/006 (72) Inventor Kunihisa Nagino Otsu, Shiga Prefecture 1-1-1 Ichizonoyama, Toray Industries, Inc. Shiga Plant F-term (reference) 5D029 JA01 LA12 LB07 LC06 MA02 MA03 MA04 5D090 AA01 BB05 CC06 DD01 EE05 KK06

Claims (14)

[Claims] 1. A method for recording, erasing and reproducing information by irradiating a laser beam, wherein recording and erasing of information is performed by a reversible phase change between an amorphous phase and a crystalline phase. An optical recording medium, comprising at least a first dielectric layer, a first boundary layer, a recording layer, a second boundary layer, an absorption correction layer, and a reflective layer on a substrate in this order, wherein the composition of the recording layer is a general formula [ [(Ge _1-k Sn _k ) _0.5 Te _0.5 ] _x (Sb _0.4 Te _0.6 )
_1-x] with _1-y Sb _y A _z (wherein, A is selected Ge, Sb, from elements belonging from Group 3 to Group 14 of the sixth period of the third period in the periodic table, except for Te X, y,
z and k are relational expressions of the following (1) or (2): 0.5 ≦ x ≦ 0.95, 0 ≦ y ≦ 0.08, 0 <z ≦ 0.2, k = 0 (1) 0.5 ≦ x ≦ 0.95, 0.01 .Ltoreq.y.ltoreq.0.08, z = 0, 0.ltoreq.k.ltoreq.0.5 (2), and the first boundary layer and the second boundary layer are carbon, carbide, oxide and nitride, respectively. Consisting of a layer containing at least one selected from the main components, and
An optical recording medium wherein the refractive index of the absorption correction layer is 1.0 or more and 4.0 or less, and the extinction coefficient is 0.5 or more and 3.0 or less. 2. The optical recording medium according to claim 1, wherein the first boundary layer comprises a layer containing carbon as a main component. 3. The optical recording medium according to claim 1, wherein both the first boundary layer and the second boundary layer are layers containing carbon as a main component. 4. The optical recording medium according to claim 1, wherein the first boundary layer or the second boundary layer comprises a layer containing germanium nitride as a main component. 5. The method of claim 1, wherein the germanium nitride is GeN _x (0.8 ≦
5. The optical recording medium according to claim 4, wherein a composition range of x ≦ 0.33) is satisfied. 6. The first boundary layer and the second boundary layer are each composed of a layer containing at least one selected from carbides, oxides and nitrides, and have a recording layer composition represented by the following formula: (Ge _0.5 Te _0.5 ) _x (Sb _0.4 Te _0.6 ) _1-x ｝ _1-yz
Sb _y A _z (wherein, A is indicated Ge, Sb, an element selected from elements belonging to Group 14 from Group 3 of the sixth period of the third period in the periodic table, except for Te, x, y , Z are relational expressions 0.5 ≦ x ≦ 0.95, 0.03 ≦ y ≦ 0.08, 0 ≦
Satisfies z ≦ 0.2. 2. The optical recording medium according to claim 1, wherein the optical recording medium is within the range represented by the formula (1). 7. The optical recording medium according to claim 1, wherein the absorption correction layer is made of a material mainly composed of a metal oxide or nitride containing at least one of Al and Cr. 8. The method according to claim 1, wherein the absorption correction layer is made of AlO _x (x = 0.3 to
The optical recording medium according to claim 7, wherein 0.8) is the main component. 9. The refractive index of the first dielectric layer is 1.9 or more and 2.4.
2. The optical recording medium according to claim 1, wherein the extinction coefficient is 0.1 or less. 10. The thickness of the first dielectric layer is not less than 50 nm and not more than 20.
0 nm or less, the thickness of the recording layer is 7 nm or more and 17 nm or less,
2. The optical recording medium according to claim 1, wherein the thickness of the absorption correction layer is 10 nm or more and 100 nm or less. 11. The optical recording medium according to claim 1, wherein the refractive index and the extinction coefficient are measured at the wavelength of a laser beam for recording or reproducing. 12. The method according to claim 1, wherein the refractive index and the extinction coefficient are measured at a wavelength of the laser beam of 660 nm.
The optical recording medium according to the above. 13. An optical recording medium comprising an optical head and an optical recording medium, irradiating a laser beam from the optical head to record information by a reversible phase change between an amorphous phase and a crystalline phase in the optical recording medium. An erasable and reproducible optical recording device, wherein the linear velocity of laser light irradiation is 7.5 × 10 ⁶ × d / s or more (d is a laser beam diameter on a recording surface) or more,
The length of the shortest mark among the recording marks recorded in the mark edge system by the laser light in the laser light traveling direction is 0.55 × d or less, and the track width of the optical recording medium is 0.7 × d or less. An optical recording apparatus, wherein the optical recording medium is the optical recording medium according to any one of claims 1 to 12. 14. The optical recording apparatus according to claim 13, wherein the wavelength of the laser light for performing recording, erasing and reproduction is 645 to 660 nm.