JP3211537B2 - Optical recording medium - Google Patents

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 capable of recording, erasing, and reproducing information by irradiating light.

In particular, the present invention relates to a rewritable phase-change optical recording medium, such as an optical disk, an optical card, or an optical tape, having a function of erasing and rewriting recorded information and capable of recording an information signal at high speed and high density. Things.

[0003]

2. Description of the Related Art The technology of a conventional rewritable phase-change optical recording medium is as follows.

[0004] These optical recording media have a recording layer mainly containing tellurium or the like. During recording, a focused laser light pulse is applied to the recording layer in a crystalline state for a short time to partially cover the recording layer. Melts. 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 marks are irradiated with a laser beam and heated to a temperature lower than the melting point of the recording layer and higher than the crystallization temperature to crystallize the recording marks in an amorphous state, and the original unrecorded data is recorded. Return to condition.

As a material of the recording layer of these rewritable phase-change optical recording media, alloys such as Ge 2 Sb 2 Te 5 (N.Ya) are used.
mada et al, Proc.Int.Symp.on Optical Memory 1987 p
61-66) are known.

An optical recording medium having a Te alloy as a recording layer has a high crystallization speed and can perform high-speed overwriting with a single circular beam only by modulating the irradiation power. In an optical recording medium using these recording layers, usually, a dielectric layer having heat resistance and light transmissivity is provided on both sides of the recording layer to prevent the recording layer from being deformed or having an opening during recording. Further, a metal reflective layer such as light-reflective Al is provided on the dielectric layer on the side opposite to the light beam incident direction to improve the signal contrast at the time of reproduction by an optical interference effect. There is known a technique which facilitates formation of a recording mark in a crystalline state and improves erasing characteristics and repetition characteristics. In particular, in the "quenched structure" in which the recording layer and the dielectric layer between the recording layer and the reflective layer are each formed to be as thin as about 20 nm, the rewriting is repeated as compared with the "gradual cooling structure" in which the dielectric layer is made as thick as about 200 nm. Is excellent in that the recording characteristics are not deteriorated due to erasure and the power margin of the erasing power is wide (T.Ohota et al, Japanese Jounal of A
pplied Physics, Vol 28 (1989) Suppl. 28-3 pp123-12
8).

[0008]

SUMMARY OF THE INVENTION The aforementioned Ge2 Sb2 T
A problem in a quenched structure rewritable phase-change optical recording medium having a ternary alloy of Te-Ge-Sb such as e5 as a recording layer is to repeat recording, erasing or rewriting, ie, melting,
The repetition of solidification tends to cause a change in the thickness of the recording film and the generation of fine openings, and the durability of repeated recording is insufficient.

An object of the present invention is to solve the above-mentioned problems of the conventional optical recording medium and to provide an optical recording medium having both repetitive durability and long-term storage stability of recording.

Another object of the present invention is to provide a long-life optical recording medium having high recording sensitivity, excellent in oxidation resistance and wet heat resistance, and free from defects even during long-term storage.

[0011]

According to the present invention, a recording layer formed on a substrate is irradiated with light to record information,
Erase, reproduction is possible, information recording and erasure, in an optical recording medium is performed by a phase change between an amorphous phase and a crystalline phase, the optical recording medium at least a recording layer, a dielectric layer and a reflective layer An optical recording medium comprising: a tellurium alloy having the following composition formula:

Compositional formula Nbz Mα (Sbx Te1-x) 1-
yz-α (Ge0.5Te0.5) y 0.35 ≦ x ≦ 0.7 0.2 ≦ y ≦ 0.5 0.0005 ≦ z ≦ 0.02 0.0005 ≦ α ≦ 0.02 where , M are Pt (platinum), Au (gold), Ag
It represents at least one metal selected from (silver), Cu (copper), and Ni (nickel). Nb is niobium, S
b represents antimony, Te represents tellurium, Ge represents germanium, and x, y, z, α and numbers represent the molar ratio of each element.

The material of the recording layer of the present invention is a chalcogen compound containing Te as a main component which can take at least two states of a crystalline state and an amorphous state.
It is substantially made of a novel non-stoichiometric composition of multi-alloy serving as a single crystal phase. Since the crystal state is a single phase, the crystallization speed is extremely high, and recording can be rewritten at high speed. Further, since the crystalline state is substantially a single phase, deterioration of recording characteristics due to composition segregation or the like is unlikely to occur.

Nb (niobium) in the above composition formula is in the range of the content represented by z in the formula, that is, 0.0005 ≦ z
When ≦ 0.02, variation in the thickness of the recording layer and occurrence of an opening in the recording layer caused by repetition of recording, erasing or rewriting many times are suppressed. Although the details of this mechanism have not been fully clarified, elements such as Te and Sb in the recording layer and Nb form a strong bond, and the viscosity of the recording layer in the high-temperature melting state is increased, so that the recording layer at the time of recording is increased. Is presumed to be due to the low fluidity. Nb has a greater effect of suppressing the above-described deterioration when recording is repeated a large number of times than other metals.

When the value of z in the above composition formula is larger than 0.02, the crystal state of the recording layer is substantially composed of a plurality of phase crystals. Are likely to occur, making erasure and rewriting difficult. Also, z
Is less than 0.0005, the above-described significant effect is not exhibited, and the repetition durability of rewriting is significantly reduced. The value of z is preferably 0.0005 or more and 0.01 or less because the crystallization speed is high and the durability of repeated rewriting is high.

Further, Pt represented by M in the above composition formula
(Platinum), Au (gold), Ag (silver), Cu (copper), Ni
At least one metal selected from (nickel) has the effect of significantly improving the thermal stability of the recording mark in the amorphous state, even in the presence of a relatively small amount. In the case of Nb described above, the degree of improvement in thermal stability is smaller than these metal elements.
The thermal stability can be further enhanced than in a recording layer containing only By this effect, an optical recording medium having excellent recording repetition durability and storage stability can be obtained as compared with an optical recording medium using a conventional recording layer material.

The value of α in the above composition formula is 0.0005 ≦
When α ≦ 0.02, the effect of improving the thermal stability is high. 0.
When the value is larger than 02, the reversibility of the repetition of recording deteriorates. When the value is less than 0.0005, the effect of improving the thermal stability is not sufficiently exhibited. The value of α is preferably 0.0005 or more and 0.005 or less because the crystallization speed is high and the thermal stability of the amorphous state of the recording mark is high.

The value of x in the above formula is 0.35 ≦ x ≦
In the range of 0.7, the crystallization speed is high, rewriting is possible at high speed, and the reversibility of rewriting is good. When it is larger than 0.7, the Sb component becomes too large, and when it is smaller than 0.35, the Te component becomes too large, and in any case, the crystallization rate is remarkably reduced, and at the same time, segregation tends to occur. Repetition of rewriting becomes difficult. The value of x is 0.4
The value of 0.5 or more is preferable because the crystallization speed is high and the repetition durability of rewriting is high.

The value of y in the above composition formula is 0.2 ≦
In the range of y ≦ 0.5, the thermal stability of the amorphous state of the recording mark is high, the crystallization speed is high, and the recording can be rewritten at high speed. When it is larger than 0.5, the thermal stability of the amorphous state is good, but the repetition durability of rewriting is extremely poor. On the other hand, when it is less than 0.2, the thermal stability of the amorphous state of the recording mark is significantly deteriorated. The value of y is preferably 0.3 or more and 0.4 or less because the repetition durability of rewriting is high and the thermal stability in an amorphous state is high.

Further, as the metal represented by M in the formula, at least one metal selected from Pt (platinum), Au (gold) and Ag (silver) is excellent in reversibility of recording and erasing. preferable. At this time, x, y,
It is further preferable that z and α each have a value in the following range.

0.4 ≦ x ≦ 0.5 0.3 ≦ y ≦ 0.4 0.0005 ≦ z ≦ 0.01 0.0005 ≦ α ≦ 0.005

A typical layer structure of the optical recording medium of the present invention is as follows.
It is composed of a laminate of a transparent substrate / first dielectric layer / recording layer / second dielectric layer / reflective layer (here, light enters from the substrate side). However, not limited to this, Si0 ₂ and ZnS does not impair the effects of the present invention on a reflective layer, Zn
A protective layer such as S-SiO _2, a resin layer such as an ultraviolet curable resin, an adhesive layer for bonding to another substrate, and the like may be provided.

The dielectric layer of the present invention has an effect of protecting the substrate and the recording layer from heat, such as preventing the substrate and the recording layer from being deformed by heat during recording and deteriorating the recording characteristics, and an optical interference effect. This has the effect of improving the signal contrast during reproduction. As this dielectric layer, ZnS, Si
There are inorganic thin films such as O ₂ , silicon nitride, and aluminum oxide. In particular, a thin film of ZnS, Si, Ge, Al, Ti,
A thin film of an oxide of a metal such as Zr or Ta, a thin film of a nitride such as Si or Al, a thin film of a carbide such as Ti, Zr, or Hf, and a film of a mixture of these compounds are preferable because of high heat resistance. Also, those obtained by mixing carbon or a fluoride such as MgF2 with these are preferable because the residual stress of the film is small. Especially mixed film of ZnS and SiO ₂ or a mixed film of ZnS and SiO ₂ and carbon are recorded, even by the repetition of erasing, preferably since the recording sensitivity, C / N, hardly occurs deterioration, such as erasure ratio, especially ZnS And Si
A mixed film of O ₂ and carbon is preferred. In this case, the composition ratio of SiO ₂ is preferably 15 to 35 mol%, and the mixing ratio of carbon is preferably 1 to 10 mol%.

The thickness of the first and second dielectric layers is about 10 to 500 nm. The thickness of the first dielectric layer is preferably 100 to 400 nm because the first dielectric layer is hardly peeled off from the substrate or the recording layer and hardly causes defects such as cracks. The thickness of the second dielectric layer is preferably 10 to 30 nm because recording characteristics such as C / N and erasure rate and stable rewriting can be performed many times.

As a material of the reflection layer, a metal such as Al or Au having light reflectivity, or a material containing these as a main component,
Alloys containing additional elements such as i, Cr, Hf and Al, A
Examples thereof include a mixture of a metal such as u and a metal compound such as a metal nitride such as Al and Si, a metal oxide, and a metal chalcogenide. Metals such as Al and Au and alloys containing these as main components are preferable because of their high light reflectivity and high thermal conductivity. As an example of the above-mentioned alloy, Al, Si, Mg, Cu, Pd, Ti, Cr, H
At least one element such as f, Ta, Nb, Mn and the like added in a total of less than 5 atomic% and 1 atomic% or more, or at least one of Au, Cr, Ag, Cu, Pd, Pt, Ni, etc. Element total less than 20 atomic% and 1 atomic%
These are the ones added above.

In particular, since the price of the material can be reduced,
An alloy containing Al as a main component is preferable, and in particular, Ti, Cr, Ta, Hf,
An alloy in which at least one or more metals selected from Zr, Mn, and Pd are added in a total of less than 5 atomic% and at least 0.5 atomic% is preferable.

In particular, since the corrosion resistance is good and hillocks and the like hardly occur, the reflection layer contains an additive element containing 0.5 to 3 atomic% in total of additive elements.
f-Pd alloy, Al-Hf alloy, Al-Ti alloy, Al
-Ti-Hf alloy, Al-Cr alloy, Al-Ta alloy,
It is preferable to use an Al-Ti-Cr alloy or an Al-Si-Mn alloy that is composed mainly of Al.

In particular, an Al alloy represented by the following composition formula is preferable because of its excellent effects. Composition formula Pdx Hfy Al1-xy and 0.0005 ≦ x ≦ 0.005, 0.005 ≦
y ≦ 0.03 Here, x, y, and 1-xy represent the molar ratio of each element.

The thickness of the reflection layer is approximately 1
0 nm or more and less than 200 nm.

Particularly, since the recording sensitivity is high, one-beam overwriting is possible at high speed, and the erasing rate is large and the erasing characteristics are good, the main part of the optical recording medium can be constituted as follows. preferable.

That is, the thickness of the first dielectric layer is 100 n
m to 400 nm, and the thickness of the second dielectric layer is 10 nm.
And the thickness of the recording layer is 10 nm to 30 nm.
nm, the thickness of the reflective layer is 30 nm to 200 nm, the dielectric layer is a mixed film of ZnS, SiO ₂ and carbon,
The mixing ratio of ₂ is 15 to 35 mol%, and the mixing ratio of carbon is 1 to 1
It is preferable that the content is 0 mol% and the composition of the recording layer is within the range represented by the following formula. Composition formula Nbz Mα (Sb
xTe1-x) 1-yz-α (Ge0.5Te0.5) y 0.35 ≦ x ≦ 0.5 0.2 ≦ y ≦ 0.5 0.0005 ≦ z ≦ 0.01 0.0005 ≦ α ≦ 0.005 where M is Pt (platinum), Au (gold), Ag (silver)
Represents at least one metal selected from the group consisting of: Also, Nb
Represents niobium, Sb represents antimony, Te represents tellurium, Ge represents germanium, and x, y, z, α and numbers represent the molar ratio of each element.

As the material of the substrate of the present invention, various transparent synthetic resins, transparent glass and the like can be used. In order to avoid the effects of dust and scratches on the substrate, it is preferable to use a transparent substrate and perform recording from the substrate side with a focused light beam.As such a transparent substrate material, glass, polycarbonate, polymethyl methacrylate, Polyolefin resin, epoxy resin, polyimide resin and the like can be mentioned. In particular, a polycarbonate resin and an amorphous polyolefin resin are preferable because they have low optical birefringence, low hygroscopicity, and are easy to mold.

The thickness of the substrate is not particularly limited, but is practically 0.01 mm to 5 mm. 0.01m
If it is less than m, even when recording with a light beam focused from the substrate side, it is susceptible to dust, and if it is 5 mm or more,
It becomes difficult to increase the numerical aperture of the objective lens, and the spot size of the irradiation light beam becomes large, so that it becomes difficult to increase the recording density. The substrate may be flexible or rigid. The flexible substrate is used in the form of a tape, a sheet, or a card. The rigid substrate is used in the form of a card or a disk. In addition, these substrates may be formed into an air sandwich structure, an air incident structure, or a close bonding structure by using two substrates after forming a recording layer or the like.

The light source used for recording on the optical recording medium of the present invention is a high-intensity light source such as a laser beam or a strobe light. Particularly, a semiconductor laser beam has a small light source, a small power consumption, Is preferred because of the simplicity.

The recording is performed by irradiating a laser beam pulse or the like to the crystalline recording layer to form an amorphous recording mark. Alternatively, a recording mark in a crystalline state may be formed on a recording layer in an amorphous state. Erasing can be performed by irradiating a laser beam to crystallize an amorphous recording mark or to make a crystalline recording mark amorphous. Since the recording speed can be increased and the recording layer is hardly deformed, it is preferable to form an amorphous recording mark during recording and crystallize during erasing.
In addition, the light intensity is high at the time of forming a recording mark and slightly weakened at the time of erasing, and one-beam overwriting in which rewriting is performed by one light beam irradiation is preferable because the time required for rewriting is reduced.

Next, a method for manufacturing the optical recording medium of the present invention will be described. Examples of a method for forming a reflective layer, a recording layer, and the like on a substrate include a known thin film forming method in a vacuum, for example, 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 state of deposition using a known technique such as a quartz oscillator film thickness meter.

The formation of the recording layer and the like may be performed while the substrate is fixed, or may be moved or rotated. The substrate is preferably rotated on its own because of excellent in-plane uniformity of the film thickness, and more preferably combined with revolution.

Further, after forming a reflective layer and the like within a range that does not significantly impair the effects of the present invention, a dielectric layer such as ZnS or SiO ₂ or a resin protection such as an ultraviolet curable resin is used to prevent scratches and deformation. Layers and the like may be provided as necessary. After the formation of the reflection layer or the like, or after the formation of the above-mentioned resin protective layer, the two substrates may be opposed to each other and bonded with an adhesive.

It is preferable that the recording layer is previously crystallized by irradiating a laser beam or a light such as a xenon flash lamp before recording is actually performed.

[0041]

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 carrier-to-noise ratio and the erasing rate (difference in the reproduced carrier signal strength after recording and after erasing) were measured by a spectrum analyzer.

The film thickness during the formation of the recording layer, the dielectric layer, and the reflection layer was monitored by a quartz oscillator film thickness meter. The thickness of each layer was measured by observing the cross section with a scanning or transmission electron microscope.

(Example 1) Thickness 1.2 mm, diameter 13c
The recording layer, the dielectric layer, and the reflection layer were formed by a high frequency sputtering method while rotating a polycarbonate substrate having spiral grooves with a pitch of 1.6 μm at 30 rpm.

First, the inside of the vacuum vessel is evacuated to 1 × 10 ^-5 Pa, and then SiO 2 is evacuated in an Ar gas atmosphere of 2 × 10 ^-1 Pa.
₂ was sputtered simultaneously with a ZnS target added with 20 mol% and a carbon mixing ratio of 3 mol%.
A first dielectric layer having a thickness of 150 nm was formed on the substrate so that Subsequently, an alloy target composed of Nb, Pt, Ge, Sb, and Te is sputtered to have a composition of Nb 0.003 Pt.
A recording layer of 0.002 Ge0.175 Sb0.26 Te0.56 with a thickness of 25 nm was formed. Further, a second dielectric layer made of the same material as that of the first dielectric layer is formed to a thickness of 20 nm, and Pd0.
Sputtering 002 Hf0.02Al0.978 alloy and film thickness 100
A reflective layer of nm was formed. Further, after taking out the disk from the vacuum container, an acrylic UV curable resin (SD-101 manufactured by Dainippon Ink Co., Ltd.) is spin-coated on the reflective layer, and cured by irradiation with ultraviolet light to form a resin layer having a thickness of 10 μm. Was formed. Further, two discs produced in the same manner were applied to a hot melt adhesive (XW3 manufactured by Toa Gosei Chemical Industry Co., Ltd.).
0) to obtain an optical recording medium of the present invention.

The recording layer on the entire surface of the optical disk was crystallized with a beam of a semiconductor laser having a wavelength of 820 nm and initialized. Then, under the conditions of a linear velocity of 6 m / sec, using an optical head having a numerical aperture of the objective lens of 0.5 and a wavelength of the semiconductor laser of 780 nm, a frequency of 3.7 MHz, a pulse width of 60 nsec, a peak power of 9 to 17 mW, and a bottom power of 1 to 1 with semiconductor laser light modulated to each condition of 4 to 9 mW
After overwrite recording 00 times, the reproduction power is 1.3m
C / N was measured under the condition of a bandwidth of 30 kHz by irradiating a semiconductor laser beam of W. In addition, this part is 1.4 MH
At z, the semiconductor laser light modulated in the same manner as above was irradiated, one-beam overwriting was performed, and the 3.7 MHz erasing rate at this time was measured. A practically sufficient C / N of 50 dB or more is obtained with a peak power of 15 mW or more, and a practically sufficient 20 dB or more and a maximum of 30 dB with a bottom power of 5 to 8 mW.
The erasure rate of B was obtained.

Further, under the conditions of a peak power of 17 mW, a bottom power of 8 mW, and a frequency of 3.7 MHz, one-beam overwriting was repeated 1,000 times and 200,000 times, and the same measurement was performed. Either change in the erasing rate was hardly degraded within 2 dB.

After the optical recording medium was placed in an environment of 80 ° C. and a relative humidity of 80% for 10,000 hours, the recorded portion was reproduced thereafter. However, the change in C / N was less than 2 dB and hardly changed. Further, the recording / rewriting is performed again, and C /
When N and the erasure rate were measured, almost no change was observed.

(Comparative Example 1) An optical recording medium having the same configuration as in Example 1 was prepared except that the composition of the recording layer of the optical recording medium of Example 1 was changed to Ge0.18Sb0.26Te0.56. The same measurement as in Example 2 was performed.

C / N is 53 dB at the beginning, 52 dB for 150 hours, 40 dB after 1000 hours, and 10 dB.
After 00 hours, remarkable deterioration was observed. From this, it became clear that the thermal stability of the recording mark was insufficient and there was a problem in the long-term storage of the recording.

Example 2 The composition of the recording layer of Example 1 was changed to N
b0.004 Au0.001 Ge0.175 Sb0.26Te0.56 and N
b0.005 Ag0.002 Ge0.175 Sb0.26Te0.56
The material of the dielectric layer is Zn mixed with 20 mol% of SiO _2.
Optical recording media having the same configuration as in Example 1 except that the S film was used were produced. The recording characteristics of these two optical recording media were measured using the same apparatus as in Example 1. In all cases, a peak power of 15 mW or more and a practically sufficient C / N of 50 dB or more
And an erasing rate of 20 dB or more sufficient for practical use and a maximum of 30 dB at a bottom power of 5 to 8 mW.

Further, under the conditions of a peak power of 17 mW, a bottom power of 8 mW, and a frequency of 3.7 MHz, the same measurement was performed after repeating one-beam overwriting 1000 times and 200,000 times. Regarding the change of the erasing rate, almost no deterioration was observed within 2 dB.

After the optical recording medium was placed in an environment of 80 ° C. and a relative humidity of 80% for 10,000 hours, the recorded portion was reproduced thereafter, but the change in C / N was less than 2 dB and hardly changed. Further, the recording / rewriting is performed again, and C /
When N and the erasure rate were measured, almost no change was observed.

Example 3 The composition of the recording layer of Example 1 was changed to N
b0.003 Cu0.002 Ge0.175 Sb0.26Te0.56 and N
Optical recording media having the same configuration as in Example 1 except that b0.003 Ni0.002 Ge0.175 Sb0.26 Te0.56 was used, respectively. The recording characteristics of these two optical recording media were measured using the same apparatus as in Example 1. 15m peak power
A practically sufficient C / N of 50 dB or more is obtained with W or more,
At a bottom power of 5 to 8 mW, a practically sufficient erasing rate of 20 dB or more and a maximum of 30 dB were obtained.

Further, under the conditions of a peak power of 17 mW, a bottom power of 8 mW, and a frequency of 3.7 MHz, one-beam overwriting was repeated 1,000 times and 200,000 times, and the same measurement was performed. Regarding the change of the erasing rate, almost no deterioration was observed within 2 dB.

After the optical recording medium was placed in an environment of 80 ° C. and a relative humidity of 80% for 5000 hours, the recorded portion was reproduced thereafter. However, the change in C / N was less than 2 dB and hardly changed. Further, the recording / rewriting is performed again, and C /
When N and the erasure rate were measured, almost no change was observed.

Example 4 An optical recording medium similar to that of Example 1 was produced except that the substrate of the optical recording medium was changed to another substrate with a format and the thickness of the reflection layer was changed to 120 nm. did.

Thereafter, under the condition that the linear velocity is 8.5 m / sec, the numerical aperture of the objective lens is 0.5 and the wavelength of the semiconductor laser is 830.
Using an optical head of nm, a pulse width of 50 nsec,
A semiconductor laser beam modulated under the conditions of a peak power of 20 mW and a bottom power of 9 mW, overwrites a random data pattern of 2-7 code (1.5T frequency 5.3 MHz) 100 times and 100,000 times on the same track.・ Recorded in mode. Thereafter, reproduction was performed, and the reproduced waveform was observed. As a result, a good reproduced waveform was obtained with almost no deterioration as compared with after the initial 100 recordings. Further, when the bit error rate (BER) of this track was measured, it was 3 × 10
It was a good value of ^-5 .

Further, a recording sector due to the movement of the recording material,
The reproduced waveform at the leading end and the trailing end of the sample was hardly distorted, and the reproduced waveform at the intermediate data portion was hardly disturbed.

Comparative Example 2 The composition of the recording layer was Ge 0.22 Sb
A conventional optical recording medium having a configuration similar to that of Example 4 except for setting it to 0.23 Te0.55, which is outside the scope of the present invention, was produced. When the recording sensitivity of this optical recording medium was measured, it was almost the same as in Example 1. This optical recording medium was used 100 times in the same manner as in Example 1,
Further, overwrite recording was repeated 100,000 times, and the reproduced waveform was observed. After 100,000 times, the variation in the thickness of the recording layer was larger than that at the 100th time, and there were many portions where the amplitude of the signal in the data portion was significantly reduced. Was seen. When the bit error rate (BER) was measured to be 3 × 10 ⁻¹ or more, even if error correction was performed, the data was deteriorated to a level at which data reproduction was quite difficult.

Further, the reproduced waveform at the leading end and the trailing end of the recording sector due to the movement of the recording material was remarkably observed.

[0061]

According to the present invention, since the composition of the recording layer of the optical recording medium is set to a specific composition, the following effects are obtained. (1) High sensitivity, high erasure rate and high C / N. (2) Even if recording and erasing are repeated a number of times, the operation is stable, and there is almost no deterioration of characteristics and generation of defects. (3) Excellent heat and moisture resistance and oxidation resistance, and long life. (4) High thermal stability of the recording mark, and excellent long-term storage stability of the recording. (5) Can be easily manufactured by sputtering. (6) Good overwrite performance can be obtained even at a high linear velocity.

Continuation of front page (56) References JP-A-6-191161 (JP, A) JP-A-2-258291 (JP, A) JP-A-6-191160 (JP, A) JP-A 1-211249 (JP) JP-A-1-277338 (JP, A) JP-A-61-258787 (JP, A) JP-A-4-223191 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B41M 5/26 G11B 7/24 511 G11B 7/24 538

Claims (3)

(57) [Claims] 1. A recording layer formed on a substrate is irradiated with light so that information can be recorded, erased, and reproduced, and the information can be recorded and erased in a phase between an amorphous phase and a crystalline phase. In the optical recording medium performed by the change, the optical recording medium has at least a recording layer, a dielectric layer and a reflective layer, and the composition of the recording layer is a tellurium alloy represented by the following composition formula. An optical recording medium characterized by the following. Compositional formula Nbz Mα (Sbx Te1-x) 1-yz-α (Ge
0.5 Te0.5) y 0.35 ≦ x ≦ 0.7 0.2 ≦ y ≦ 0.5 0.0005 ≦ z ≦ 0.02 0.0005 ≦ α ≦ 0.02 where M is Pt ( Platinum), Au (gold), Ag
It represents at least one metal selected from (silver), Cu (copper), and Ni (nickel). Nb is niobium, S
b represents antimony, Te represents tellurium, Ge represents germanium, and x, y, z, α and numbers represent the molar ratio of each element. 2. The optical recording medium according to claim 1, wherein the composition of the recording layer is a tellurium alloy represented by the following composition formula. Compositional formula Nbz Mα (Sbx Te1-x) 1-yz-α (Ge
0.5 Te0.5) y 0.4 ≦ x ≦ 0.5 0.3 ≦ y ≦ 0.4 0.0005 ≦ z ≦ 0.01 0.0005 ≦ α ≦ 0.005 where M is Pt ( Platinum), Au (gold), Ag (silver)
Represents at least one metal selected from the group consisting of: 3. The optical recording medium according to claim 1, wherein the composition of the reflection layer is an Al alloy represented by the following composition formula. Composition formula Pdx Hfy Al1-xy 0.0005 ≦ x ≦ 0.005 0.005 ≦ y ≦ 0.03 Here, x, y, and 1-xy represent the molar ratio of each element.