JPH1148611A - Optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium being excellent in repeated record erasing property by providing a recording layer wherein the composition ratios for Au, In, Sb and Te are specified. SOLUTION: This optical recording medium 1 has a structure wherein a lower dielectric layer 3, a recording layer 4, an upper dielectric layer 5, a reflective layer 6 and a protective layer are laminated by this order on a base plate 2. In the recording layer 4, the range of a composition ratio α for Au is made 1 atom% <=α<=16 atom%, the range of a composition ratio β for In is made 8 atom% <=β<=17 atom%, the range of a composition ratio γ for Sb is made 41 atom% <=γ<=63 atom%, and the range of a composition ratio δ for Te is made 24 atom% <=δ<= 36 atom%. In this case, it is taken as 99 atom% <=α+β+γ+δ<= 100 atom%. This recording layer 4 indicates a favorable recording erasing property when a relative speed of the recording layer for a light beam at the time of recording erasing is 5-7 m/s.

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 having a recording layer made of a phase-change recording material, and more particularly, to a recording medium having a relative speed of 5 to 7 m / sec.
s relates to an optical recording medium.

[0002]

2. Description of the Related Art In recent years, an optical recording medium capable of high-density recording and capable of erasing and rewriting recorded information has attracted attention. Among the rewritable optical recording media, a phase-change optical recording medium changes the crystal state of the recording layer by irradiating a laser beam, and detects a change in the reflectance of the recording layer due to such a state change. Things. The phase change type optical recording medium is excellent in that overwriting can be performed by a single light beam, and the optical system of the driving device is simpler than that of the magneto-optical recording medium.

As a material for a recording layer of a phase-change optical recording medium, a Ge-Te-based material having a large difference in reflectance between a crystalline state and an amorphous state and having a relatively high amorphous state stability. Is often used. Typical examples of the material include Ge-Te and Ge-T as disclosed in U.S. Patent No. 3,530,441.
e-Sb-S, Ge-Te-S, Ge-Se-S, Ge-Se-Sb, Ge-As-Se, In
So-called chalcogen-based alloy materials such as -Te, Se-Te and Se-As.

In order to improve the stability and the high-speed crystallization, Au (Japanese Patent Application Laid-Open No. 61-219692), Sn and Au
(JP-A-61-270190), Pd (JP-A-62-19490), etc., and the composition of Ge-Te-Se-Sb for the purpose of improving the recording / erasing repetition performance A material having a specified ratio (JP-A-62-73438) has also been proposed. However, none of the above-described compositions can satisfy all of the properties required for the recording layer of the phase-change rewritable optical recording medium. In particular, recording sensitivity,
The most important issues are to improve the erasing sensitivity, to prevent the erasing ratio from being reduced due to the unerased portion at the time of overwriting, and to prolong the life of the repeated recording and erasing characteristics of the recorded and unrecorded portions.

On the other hand, it has recently been proposed to apply a compound called chalcopyrite. Chalcopyrite type compounds have been widely studied as compound semiconductor materials and have been applied to solar cells and the like. The chalcopyrite type compound can be obtained from Ib-IIIb-VIb ₂ by using the chemical periodic table.
A composition represented by or IIb-IVb-Vb _2, have two stacked diamond structures.

Among these chalcopyrite-type compounds, it is known that AgInTe ₂ can be used as a recording layer material of an optical recording medium having a linear velocity of about 7 m / s by diluting it with Sb or Bi (see, for example). JP-A-3-240590, JP-A-3-166268, JP-A-3-82593, JP-A-3-73
No. 384, etc.). In addition to the phase-change optical recording media using such chalcopyrite-type compounds, JP-A-4-267192, JP-A-4-232779, and JP-A-6-166268 disclose that the recording layer is crystallized. There is disclosed a phase change type optical recording medium in which an AgSbTe ₂ phase is generated at the time. Optical recording media using these recording materials have excellent C / N, erasure ratio, modulation degree, and recording sensitivity.

[0007]

However, the recording layer of the chalcopyrite-type compound having the above-mentioned composition has a repetitive recording and erasing life of only several thousand times and a magneto-optical disk has a repetitive recording and erasing life of 100,000 times. There was a problem that it was not always enough compared to that.

The present invention has been made in view of such conventional problems,
It is an object of the present invention to provide an optical recording medium having a high C / N, an erasing ratio, a degree of modulation, a recording sensitivity, and an excellent repetitive recording / erasing characteristic.

[0009]

According to the present invention, there is provided an optical recording medium according to the first aspect of the present invention, wherein a relative speed of recording and erasing of a recording layer with respect to a light beam is 5 to 7 m / s. In, each represented by α, β, γ, and δ,
The composition ratio of Au, In, Sb, and Te is 1 atomic% ≦ α ≦ 16
Atomic%, 8 atomic% ≦ β ≦ 17 atomic%, 41 atomic% ≦ γ ≦ 63 atomic%, 24 atomic% ≦ δ ≦ 36 atomic%, provided that 99 atomic% ≦ α
+ Β + γ + δ ≦ 100 at%, characterized by having a recording layer. Of these, 2 atomic% ≦ α ≦ 10 atomic%, 10 atomic%
The composition ranges of atomic% ≦ β ≦ 16 atomic%, 45 atomic% ≦ γ ≦ 59 atomic%, and 26 atomic% ≦ δ ≦ 34 atomic% are particularly preferable.

In the optical recording medium having such a configuration, C /
In addition to N, the erasing ratio, the degree of modulation, and the recording sensitivity, the repetitive recording / erasing characteristics are also improved. The technology in which the recording layer may contain Au, In, Sb, and Te is described in, for example, JP-A-60-177446, JP-A-1-307034, and
This can be seen in JP 303643, JP-A 1-241340 and the like.

However, Japanese Patent Application Laid-Open No. 60-177446 discloses
JP-A-1-307034 and JP-A-1-303643, a number of elements constituting the recording layer are listed, among various combinations of these elements, Au, In, Sb, Te Can only be shown to be theoretically possible, and there is no description or suggestion about a recording layer containing the specific element in a specific ratio as in the present invention.

On the other hand, Japanese Unexamined Patent Publication No. Hei 1-241340 discloses Au, I
A recording layer in which the composition ratio of four elements of n, Sb, and Te is specified in a wide range is disclosed. Specifically, Au is 0 to 30 atomic%,
It is considered that In is variable within a range of 5 to 80 atomic%, Sb is variable within a range of 10 to 90 atomic%, and Te is variable within a range of 0 to 50 atomic%, and the composition ratio of the above four elements according to the present invention may be included. There is also. However, in Japanese Patent Application Laid-Open No. 1-241340, it is recognized that Au and In may be 0 atomic% (that is, Au and In are not indispensable constituent elements). There is no description or suggestion about improvement of various characteristics (C / N, erasing ratio, modulation degree, recording sensitivity, repetitive erasing characteristics, etc.) of the recording layer aimed at by the present invention.

In the optical recording medium of the present invention, the composition ratio α of Au is 1 atomic% ≦ α ≦ 16 atomic%, the composition ratio β of In is 8 atomic% ≦ β ≦ 17 atomic%, and the composition ratio of Sb is The range of the ratio γ is 41 at% ≦ γ ≦ 63 at%, and the range of the composition ratio δ of Te is 24
Atomic% ≦ δ ≦ 36 At%. More preferred composition ranges are 2 atomic% ≦ α ≦ 10 atomic%, 10 atomic% ≦ β ≦ 16 atomic%, 45 atomic% ≦ γ ≦ 59 atomic%, 26 atomic% ≦ δ ≦ 34 atomic%
It is.

When β, γ, and δ are in the above composition ranges, if α is less than 1 atomic%, the crystal transition rate is reduced, and the erasing ratio is reduced. In addition, the life of repeated recording / erasing is reduced. If α exceeds 16 atomic%, the crystal transition speed becomes too fast, and it becomes difficult to sufficiently record. Regarding the composition range of β, good recording and erasing characteristics were obtained in all the studied composition ranges of 8 at% ≦ β ≦ 17 at%.

When α and β are in the above composition ranges, if γ is less than 41 at%, the crystal transition rate becomes slow and erasure becomes difficult. In addition, good recording and erasing characteristics were obtained in all the composition ranges studied up to γ = 63 atomic%. α
When δ exceeds 36 atomic%, when β and β are in the above composition range, the crystal transition speed becomes slow and erasure becomes difficult. At the same time, the absorption coefficient increases, the optical interference effect due to multiple reflection on the dielectric layer decreases, and the C / N decreases. In addition, good recording and erasing characteristics were obtained in all the composition ranges studied up to δ = 24 atomic%.

In the recording layer, in addition to the above-mentioned elements of Au, In, Sb, and Te, for example, Cu, Ag, Ni, Z
Other elements such as n, Fe, Ge, Se, S, Sn, Pd, V, As, C, N, and O may be contained, but the total content of these elements is 1% by atomic ratio. The following is preferred. The recording layer having the composition described above exhibits good recording / erasing characteristics when the relative speed of recording / erasing of the recording layer with respect to the light beam is 5 to 7 m / s. As a specific structure of the optical recording medium, as in the invention according to claim 2, a lower dielectric layer,
A single-sided recording layer in which the recording layer, the upper dielectric layer, the reflective layer, and the protective layer are laminated in this order is simple.

Further, as in the invention according to claim 3, two optical recording media in which at least a lower dielectric layer, the recording layer, an upper dielectric layer, and a reflective layer are respectively laminated on a substrate in this order. May be bonded to each other with the reflection layer side facing and bonded via an adhesive layer, so that double-sided recording is possible. Further, as in the invention according to claim 4, at least a lower dielectric layer, the recording layer, an upper dielectric layer, a reflective layer,
The adhesive layer and the upper substrate may be laminated in this order to increase the mechanical strength.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are cross-sectional views showing preferred examples of the configuration of the optical recording medium of the present invention. The optical recording medium 1 shown in FIG. 1 has a structure in which a lower dielectric layer 3, a recording layer 4, an upper dielectric layer 5, a reflective layer 6, and a protective layer 7 are laminated in this order on a substrate 2. This is an optical recording medium for single-sided recording.

The optical recording medium 1 shown in FIG. 2 has a lower dielectric layer 3, a recording layer 4, an upper dielectric layer 5,
This is an optical recording medium for single-sided recording in which the reflective layer 6, the protective layer 7, the adhesive layer 8, and the upper substrate 9 are laminated in this order to increase the mechanical strength. In the optical recording medium 1 shown in FIG. 3, a lower dielectric layer 3, a recording layer 4, an upper dielectric layer 5, a reflective layer 6, and a protective layer 7 are formed on two substrates 2 in this order. This optical recording medium for double-sided recording is obtained by bonding these two optical recording media with the protective layer 7 side facing each other and bonding via an adhesive layer 8.

In the optical recording medium shown in FIGS. 2 and 3, the protective layer 7 can be omitted. The substrate 2 is preferably made of a material that is transparent to the light beam to be used, for example, resin or glass, and is particularly preferably resin because it is easy to handle and inexpensive. Specifically, for example, a polycarbonate resin, an acrylic resin, an epoxy resin, an ABS resin, or the like can be used as the resin. The shape and dimensions of the substrate are not particularly limited, but are usually disk-shaped, the thickness is usually about 0.5 to 3 mm, and the diameter is 40 mm.
It is about 360 mm. In addition, a predetermined pattern such as a groove is provided on the surface of the substrate for tracking, addressing, and the like as necessary.

The lower dielectric layer 3 and the upper dielectric layer 5 use the multiple reflection between the lower dielectric layer 3 and the upper dielectric layer 5 to reflect the change in the reflectance accompanying the change in the crystal state of the recording layer 4. Has the effect of increasing the degree of modulation (difference in the reflectance between the crystalline state and the amorphous state) and releasing the heat remaining in the recording layer 4 at an appropriate rate by heat conduction during recording. .

The dielectric used for the lower dielectric layer 3 and the upper dielectric layer 5 is preferably an inorganic substance that is substantially transparent to the light beam used. Further, the melting point of the inorganic substance is preferably higher than the melting point of the material forming the recording layer 4. Specific examples of dielectric materials include, for example, SiO ₂ , SiO ₂ , ZnO
, Al ₂ O ₃ , TiO ₂ , SnO ₂ , In ₂ O ₃ , MgO, metal oxide such as ZrO ₂ , Si ₃ N ₄ , nitride such as AlN, BN, TiN, ZrN, Zn
S, In ₂ S _3, TaS sulfides such as _{4, SiC, TaC, WC,} TiC,
Examples thereof include carbides such as ZrC and B ₄ C, diamond-like carbon, and mixtures thereof. These materials can be used alone or as a mixture of two or more materials. Further, it may contain impurities as needed. The dielectric layer is formed by sputtering, vacuum evaporation, plasma
It can be formed by a vapor phase growth method such as a CVD method, a photo CVD method, and an electron beam evaporation method.

From the viewpoint of optical characteristics, the lower dielectric layer 3 has a thickness of about 50 to 300 nm and the upper dielectric layer 5 has a thickness of 10 to 60 nm or 100 to 250 nm. And a high degree of modulation that effectively utilizes the effect of multiple reflection of. On the other hand, thermally, when the thickness of the upper dielectric layer 5 is small,
The effect of insulating the space between the recording layer 4 and the reflective layer 6 is reduced,
The heat stored in the recording layer 4 at the time of recording is quickly dissipated to the metal reflective layer 6 having a high heat radiation effect. Therefore, 10-60
In order to realize recording and erasing on an optical recording medium having an upper dielectric layer 5 as thin as about nm, the recording material needs to have high sensitivity to heating by laser light.

Conventionally, in an optical recording medium using a chalcogen-based recording material such as Ge-Sb-Te, the thickness of the upper dielectric layer 5 is set to 100 to 250 nm because the recording material does not have sufficient sensitivity.
The structure was taken. On the other hand, the recording materials of the Ag-In-Sb-Te alloy and the Au-In-Sb-Te alloy of the present invention have high sensitivity to heating by laser light. In an optical recording medium, the thickness of the upper dielectric layer 5 can be set to 10 to 60 nm. This structure is of a quenching type in which the cooling rate of the recording layer 4 during recording is high, and thus has the advantage that the edges of the recording pits become clear and the jitter is reduced. In addition, since the film thickness is small, the time for forming the upper dielectric layer 5 by sputtering or the like can be shortened, which leads to an improvement in productivity.

The recording layer 4 has a composition ratio of Au, In, Sb, and Te represented by α, β, γ, and δ, respectively, where 1 atomic% ≦
α ≦ 16 atomic%, 8 atomic% ≦ β ≦ 17 atomic%, 41 atomic% ≦ γ
It is formed of a chalcopyrite-type compound in which ≦ 63 at% and 24 at% ≦ δ ≦ 36 at% (however, 99 at% ≦ α + β + γ + δ ≦ 100 at%). Although the thickness of the recording layer 4 is not particularly limited, it is usually 10 to 200 nm, in particular, in order to realize a high reflectance and a high degree of modulation (a large difference in reflectance between a recorded state and an unrecorded state). It is preferably 15 to 150 nm.

The method for forming the recording layer 4 is not particularly limited, but may be a sputtering method, a vacuum evaporation method, a plasma CVD method,
It is preferably formed by a vapor phase growth method such as a CVD method and an electron beam evaporation method. It is convenient to measure the composition of the formed recording layer 4 using an X-ray microanalyzer.
Other analysis methods such as fluorescent X-ray, Rutherford backscattering, Auger electron spectroscopy, and emission analysis are conceivable, but when using them, it is necessary to calibrate with a value obtained by an X-ray microanalyzer.

For determining the crystal state of the substance contained in the recording layer 4, X-ray diffraction or electron diffraction is suitable. For example, when a spot-like or Debye-ring pattern is observed in the electron beam diffraction image, the crystal state can be determined, and when a ring-shaped pattern or a halo pattern is observed, the amorphous state can be determined. The material of the reflective layer 6 is not particularly limited, but may be usually made of a single metal such as Al, Au, Ag, Pt, Cu, or a high-reflectivity metal such as an alloy containing one or more of these. The thickness of the reflective layer 6 is preferably 30 to 300 nm. If the thickness is less than 30 nm, it is difficult to obtain a sufficient reflectance, and the effect of releasing the heat remaining in the recording layer 4 during recording is reduced. Further, even if it exceeds 300 nm, no remarkable improvement in the reflectance and the heat emission effect is observed. The reflective layer is preferably formed by a vapor phase growth method such as a sputtering method or an evaporation method.

The protective layer 7 is provided for improving scratch resistance and corrosion resistance. The protective layer 7 is preferably composed of various organic substances, but is particularly preferably composed of a substance obtained by curing a radiation-curable compound or a composition thereof with radiation such as electron beams or ultraviolet rays. preferable. The thickness of the protective layer 7 is usually about 0.1 to 100 μm, and may be formed by an ordinary method such as spin coating, gravure coating, spray coating, or the like.

The adhesive layer 8 is desirably made of various organic materials, but is preferably made of a thermoplastic material, a sticky material,
The radiation-curable compound or the composition thereof is preferably composed of a substance cured by an electron beam or radiation. The thickness of the adhesive layer 8 is usually about 0.1 to 100 μm, and may be formed by an optimum method selected according to the material constituting the adhesive layer 8, for example, spin coating, gravure coating, spray coating, roll coating, or the like. .

The upper substrate 9 can be made of the same resin as the substrate 2 described above. Generally, at the time of producing a phase-change optical recording medium, the recording layer 4 is in an amorphous state,
In order to obtain an overwritable optical recording medium, it is necessary to crystallize (initialize) the recording layer 4 by some method. As a method for initializing the optical recording medium 1, various methods such as a method using a semiconductor laser, a method using an Ar laser, and a method using a flash lamp can be used. In particular, the method of performing initialization using a high-output semiconductor laser is excellent in the homogeneity of the film forming the recording layer 4 after initialization, the signal characteristics of the optical recording medium 1, and the productivity. The beam diameter is suitably 0.5 to 5 μm in width and 10 to 300 μm in length. A power of 100 to 3000 mW and a linear velocity of 1 to 20 m / s are suitable.

In the optical recording medium 1 of the present invention, recording and reproduction are performed as follows. In the optical recording medium 1, the entire surface of the recording layer 4 is crystallized in the initialized state. A recording light beam (laser light beam) is applied to the crystallized recording layer 4.
Is irradiated, the irradiated part is melted by the energy of the light beam. Then, since the temperature of the melted portion drops rapidly after passing through the recording light beam, this portion becomes amorphous and becomes a signal recording portion.

When rewriting the recording information, a recording light beam is applied to a recording portion where a new signal is to be written, and an erasing light beam is applied to other portions. At this time, the power of the erasing light beam is weaker than the power of the recording light beam, and the irradiation portion of the erasing light beam is adjusted to be heated to a temperature higher than the crystallization temperature (or glass transition temperature) of the recording layer 4 and lower than the melting point. I do.

The portion irradiated with the recording light beam is melted irrespective of whether it is crystalline or amorphous before the irradiation, and becomes amorphous by rapid cooling after passing through the beam. on the other hand,
The part irradiated with the erasing beam is not changed when the part is crystalline, and is crystallized when the part is amorphous because it is heated to a temperature higher than the crystallization temperature (lower the melting point). Therefore, at the time of rewriting, even if the state before beam irradiation is crystalline or amorphous, the recording light beam irradiated part of the recording layer 4 is all an amorphous signal recording part, and All the irradiating portions of the erasing light beam are crystallized, and overwriting can be performed.

The recording light beam and the erasing light beam can be supplied from one light source by modulating the intensity of a single light beam. It is preferable that the recording light beam is irradiated in a multi-pulse form as shown in FIG. By recording one signal with at least two irradiations of pulsed light, heat storage at a recording portion is suppressed,
Since swelling (tear drop phenomenon) at the rear end of the recording portion can be suppressed, C / N and jitter are improved. Specific values of the power Pw of the recording light beam and the power Pe of the erasing light beam can be experimentally determined according to the wavelength of the light beam to be used. In the drawing, Pb indicates bottom power.

The reproducing light beam is a low-power beam that does not heat the recording layer 4 above its crystallization temperature and does not affect the crystalline state and the amorphous state of the recording layer 4. It can be determined according to the wavelength of the light beam used. In the optical recording medium of the present invention, the relative speed of the recording layer with respect to the recording and erasing light beams is 5 to 7 m / s.
Use as

Next, the present invention will be described in more detail with reference to specific examples of the present invention. However, these examples do not limit the present invention in any way. Diameter 120 mm, thickness 0.6 mm
A lower dielectric layer 3, a recording layer 4, an upper dielectric layer 5, a reflective layer 6, and a protective layer 7 are laminated in this order on two polycarbonate substrates 2 having lands / grooves of The two optical recording media were joined via an adhesive layer 8 with the protective layer 7 facing the optical recording medium 1 to obtain an optical recording medium 1 having the configuration shown in FIG. The land / groove of the substrate 2 had a track pitch of 0.74 μm and a depth of 70 nm.

The lower dielectric layer 3 is made of ZnS-SiO ₂ (SiO ₂ : 20 m
ol%) as a target and produced by an RF sputtering method. The thickness of the lower dielectric layer 3 was 140 nm. Recording layer 4
Was fabricated by mounting each chip of Au, In, Sb, Te, and Ag on an In-Sb-Te target, changing the composition, and using a DC sputtering method. The thickness of the recording layer 4 was 22 nm.

The composition of the recording layer 4 was ED manufactured by Philips.
The measurement was performed by an X-ray microanalyzer using an AX apparatus system. That is, after a recording layer 4 having a recording layer of about 50 nm was formed on a polycarbonate flat plate by a sputtering method, the energy spectrum of the sample was detected by an X-ray microanalyzer. The background of the polycarbonate flat plate and the like was removed from the detected energy spectrum, and the energy spectrum of only the recording layer 4 was derived. From the energy spectrum, the constituent elements of the recording layer 4 are quantified,
The composition of the recording layer 4 was used.

The upper dielectric layer 5 was formed in the same manner as the lower dielectric layer 3. The thickness of the upper dielectric layer 5 was 25 nm.
The reflection layer 6 was formed by a DC sputtering method using Al as a target. The thickness was 100 nm. The protective layer 7 was formed by applying an ultraviolet curable resin by a spin coating method, and then curing the applied resin by ultraviolet irradiation. The thickness of the protective layer 7 after curing was 10 μm.

The adhesive layer 8 was formed by applying an ultraviolet curable resin by a screen coating method and then curing the resin by irradiation with ultraviolet light. The thickness of the adhesive layer 8 after curing was 30 to 50 μm. The recording layer 4 after the production of the optical recording medium 1 was amorphous. For this reason, the recording layer 4 was sufficiently crystallized by a high-output semiconductor laser beam having a wavelength of 810 nm to be in an initialized state.

The evaluation of the optical recording medium 1 is performed by irradiating a semiconductor laser beam having a wavelength of 635 nm from the substrate 2 side through an objective lens with NA = 0.6, and narrowing the surface of the recording layer 4 to a spot diameter of about 1 μm. Was. At the time of recording, recording was performed by changing the irradiation laser pulse to multi-pulse. Disc characteristics include C / N, erasure ratio, modulation degree,
And the four lifespan of repeated recording and erasure were measured by the following methods.

That is, C / N records a signal having a linear velocity of 6.0 m / s and a recording frequency of 4.86 MHz (3T of 8/16 modulation system).
The C / N of the reproduced signal was measured when it was reproduced at a linear velocity of 6.0 m / s. The erasure ratio is to record a signal with a recording frequency of 4.86 MHz (3T in 8/16 modulation method) at a linear velocity of 6.0 m / s, and then overwrite a signal with a recording frequency of 1.32 MHz (11T in 8/16 modulation method). It was obtained from the carrier level difference (C2-C1) at a linear velocity of 6.0 m / s and a frequency of 4.86 MHz. Here, C1 is the linear velocity 6.0 m / s after 3T recording, the carrier level at a frequency of 4.86 MHz, and C2 is the linear velocity after 11T overwriting.
It is the residual carrier level at 6.0m / s and frequency 4.86MHz.

The modulation was linear velocity 6.0 m / s and recording frequency 1.32.
It was determined from the difference {(R1−R2) / R1} between the reflectance levels of the unrecorded portion and the recorded portion obtained from the reproduced signal when a signal of MHz (11T of the 8/16 modulation method) was recorded. Here, R1 is a reproduced signal level of an unrecorded portion, and R2 is a reproduced signal level of a recorded portion. Repeated recording and erasing characteristics are linear velocity
Overwrites 8/16 modulation random signal repeatedly at 6.0m / s, linear velocity 6.0m every 500 overwrites
The reproduction was performed at / s, and the jitter of the random signal was measured.
The number of times that jitter exceeded 15% of the reference clock (29.18 MHz) was defined as the life of repeated recording and erasing. [Example 1] In the recording layer 4, Au: 9.6, In: 11.4, Sb: 4
5.2, using a composition of 33.8 Te, on two polycarbonate substrates (0.6 mm), ZnS-SiO ₂ (140 nm) / Au-In-
Sb-Te (22 nm) / ZnS-SiO ₂ (25 nm) / Al (100 nm) / ultraviolet curable resin (10 μm) are laminated in this order, and these two optical recording media are placed with the protective layer 7 side facing. Then, the optical recording medium 1 joined through the adhesive layer 8 was produced.

The evaluation as an optical recording medium was performed by changing the recording power, erasing power of 6 mW, multi-pulse bottom power of 1 mW, and reproduction power of 1 mW by the method described above. Table 1 shows the results.

[0045]

[Table 1]

Sufficient C / N, erasure ratio, and degree of modulation were obtained even with a low recording power. [Example 2] In the recording layer 4, Au: 4.6, In: 10.4, Sb: 5
Using a composition of 5.6, Te: 29.4, a polycarbonate substrate (0.
6mm), and ZnS-SiO ₂ (140nm) / Au-In-Sb-Te (2
2nm) / ZnS-SiO ₂ (25nm) / Al (100nm) / UV curable resin (10
μm) were laminated in this order, and an optical recording medium 1 was prepared in which the two optical recording media were joined via an adhesive layer 8 with the protective layer 7 side facing each other.

The optical recording medium was evaluated by the above-described method under the conditions of changing the recording power, erasing power 6 mW, multi-pulse bottom power 1 mW, and reproducing power 1 mW. Table 2 shows the results.

[0048]

[Table 2]

Sufficient C / N, erasure ratio, and degree of modulation were obtained even with a low recording power. [Examples 3 to 18, Comparative Examples 1 to 6] ZnS-SiO2 (140 nm) / Au on _two polycarbonate substrates (0.6 mm), respectively.
-In-Sb-Te (22 nm) / ZnS-SiO ₂ (25 nm) / Al (100 nm) / ultraviolet curable resin (10 μm) are laminated in this order, and these two optical recording media are placed on the protective layer 7 side. Optical recording media 1 having the configuration of the optical recording medium 1 opposing and bonded via the adhesive layer 8 and having a different composition of the recording layer 4 were produced, and evaluated as the optical recording medium by the above-described method. .

The recording power was 12 mW, the erasing power was 6 mW, the bottom power of the multipulse was 1 mW, and the reproducing power was 1 mW.
Table 3 shows the results of C / N and repeated recording / erasing characteristics as the disk characteristics. As for the repetitive recording and erasing characteristics, the jitter was 15
%, For example, "1,
000 to 10,000 "and so on. This indicates that the characteristics can be changed within the indicated range depending on the manufacturing conditions and the evaluation conditions.

[0051]

[Table 3]

The composition ratio α of Au is 1 atom% ≦ α ≦ 16 atom%, the composition ratio β of In is 8 atom% ≦ β ≦ 17 atom%, the composition ratio γ of Sb is 41 atom% ≦ γ ≦ 63 atom% , Te has a composition ratio δ
24 atomic% ≦ δ ≦ 36 atomic% (however, 99 atomic% ≦ α + β +
The optical recording media of Examples 3 to 18 having the recording layer having a composition within the range of (γ + δ ≦ 100 atomic%) are compared with the optical recording media of Comparative Examples 1 to 6 having the recording layer having the composition outside the above range. It can be seen that good disc characteristics are exhibited.

In particular, 2 at% ≦ α ≦ 10 at%, 10 at%
≦ β ≦ 16 atomic%, 45 atomic% ≦ γ ≦ 59 atomic%, 26 atomic% ≦
δ ≦ 34 atomic% (however, 99 atomic% ≦ α + β + γ + δ ≦ 10
Example 4 having a recording layer having a composition in the range of 0 atomic%).
The optical recording media of Example 5, Example 8, Example 10, and Example 17 have excellent characteristics. Further, the following experiment was performed for comparison with a recording layer containing a different element. Comparative Example 7 Except that Ag-In-Sb-Te was used for the recording layer 4,
Optical recording media having the same layer configuration as in Examples 3 to 18 were produced, and the C / N and the repetitive recording / erasing characteristics were evaluated under the same conditions as in Examples 3 to 18 described above. Table 4 shows the results.

[0054]

[Table 4]

In Comparative Example 7, the number of times of repeated recording and erasing was 1,00.
It ranges from 0 to 2,000, up to 2,000. On the other hand, in Examples 3 to 18, repetitive recording and erasing times of 1,000 to 10,000 times or more were obtained, and it was found that disc characteristics were superior to those of Comparative Example 7 having a recording layer having a composition containing a different element.

[0056]

As described above, according to the first aspect of the present invention, there is provided an optical recording medium in which the relative speed at the time of recording / erasing of a recording layer with respect to a light beam is 5 to 7 m / s.
The C / N, the erasure ratio, the degree of modulation, the recording sensitivity are high, and the effect of repeatedly improving the recording / erasing characteristics can be obtained.

According to the second aspect of the present invention, there is an effect that an optical recording medium for single-sided recording having excellent characteristics with a simple layer structure can be obtained. Further, according to the third aspect of the invention, there is an effect that an optical recording medium for double-sided recording having excellent characteristics can be obtained. Further, according to the invention of claim 4, there is an effect that an optical recording medium having high mechanical strength and durability and excellent characteristics can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a layer configuration of an optical recording medium of the present invention.

FIG. 2 is a sectional view showing another example of the layer configuration of the optical recording medium of the present invention.

FIG. 3 is a sectional view showing still another example of the layer configuration of the optical recording medium of the present invention.

FIG. 4 is a diagram showing an example of a pulse strategy at the time of overwriting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical recording medium 2 Substrate 3 Lower dielectric layer 4 Recording layer 5 Upper dielectric layer 6 Reflective layer 7 Protective layer 8 Adhesive layer 9 Upper substrate Pw Recording power Pe Erase power Pb Bottom power

Claims (4)

[Claims] 1. In an optical recording medium used at a relative speed of 5 to 7 m / s when recording and erasing a recording layer with respect to a light beam, Au, In, and Au are represented by α, β, γ, and δ, respectively. ,
The composition ratio of Sb and Te is 1 atomic% ≦ α ≦ 16 atomic%, 8 atomic% ≦ β ≦ 17 atomic%, 41 atomic% ≦ γ ≦ 63 atomic%, 24 atomic% ≦ δ ≦ 36 atomic%, An optical recording medium comprising: a recording layer satisfying the condition: 99 atomic% ≦ α + β + γ + δ ≦ 100 atomic%. 2. A method according to claim 1, wherein a lower dielectric layer, said recording layer,
The optical recording medium according to claim 1, wherein an upper dielectric layer, a reflective layer, and a protective layer are laminated in this order. 3. At least a lower dielectric layer, the recording layer,
2. The optical recording device according to claim 1, wherein two optical recording media in which an upper dielectric layer and a reflective layer are respectively stacked on a substrate in this order are joined via an adhesive layer with the reflective layer side facing each other. Medium. 4. The optical recording medium according to claim 1, wherein at least a lower dielectric layer, said recording layer, an upper dielectric layer, a reflective layer, an adhesive layer, and an upper substrate are laminated on the substrate in this order.