JP2001126315A - Optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a phase change type optical recording medium having high sensitivity and enhanced durability without increasing the thickness of the reflecting layer and capable of increasing repetitive overwriting frequency. SOLUTION: A 1st dielectric layer 2, a recording layer 3, a 2nd dielectric layer 4 and a reflecting and heat releasing layer 5 are successively laminated on a substrate 1 to obtain the objective optical information recording medium 10 in which information is recorded and erased by the change of the arrangement of atoms constituting the recording layer 3 by irradiation with light. The reflecting and heat releasing layer 5 is an alloy layer based on Ag and containing at least one element selected from Al, Au, Cu, Co, Ni, Ti, V, Mo, Mn, Pt, Si, Nb, Fe, Ta, Hf, Ga, Pd, Bi, In, W and Zr.

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 on which information is recorded and erased by changing the arrangement of atoms by irradiating light. Information recording medium (optical disk)
About.

[0002]

2. Description of the Related Art Information recording by laser beam irradiation,
As one of the rewritable and erasable optical memory media, a so-called phase-change type recording medium utilizing a transition between crystal and amorphous or between two crystal phases of crystal 1 and crystal 2 is well known. The phase-change recording medium includes a recording layer mainly composed of a chalcogen such as Te and Se, a light-transmitting dielectric layer sandwiching the recording layer from both sides, and reflection and radiation provided opposite to the laser beam incident side. It is composed of a layer (reflection layer) and a protective layer.

[0003] The recording principle is as follows. The recording layer immediately after film formation is in an amorphous state and has a low reflectance. Therefore, first, the recording layer is heated by irradiating a laser beam to bring the entire surface of the disc into a crystalline state having a high reflectance. That is, initialization is performed. The initialized optical disk is locally irradiated with a laser beam to melt and rapidly cool the recording film, thereby changing the phase to an amorphous state. The optical properties (reflectance, transmittance, complex refractive index, etc.) of the recording film change with the phase change, and information is recorded. Reproduction is performed by irradiating a laser beam weaker than at the time of recording and detecting a reflectance difference or a phase difference between the crystal and the amorphous. In rewriting, a recording peak power superimposed on a low-energy erasing power causing crystallization is applied to a recording layer to overwrite a recording mark already recorded without going through an erasing process.

Typical material systems include GeSbTe system, Ag
InSbTe-based materials are well known and have been put to practical use. The following are known as phase change recording media using a GeSbTe-based or AgInSbTe-based material for the recording layer. That is, JP-A-1-277338 discloses (Sb _x Te _1-x ) _1-y M _y (where the atomic ratio x is 0.4 ≦
x <0.7, atomic ratio y is y ≦ 0.2, M is Ag, Al,
As, Au, Bi, Cu, Ga, Ge, In, Pb, P
An optical recording medium having a recording layer made of an alloy having a composition represented by at least one element selected from the group consisting of t, Se, Si, Sn and Zn) has been proposed. In this medium, the crystallization temperature is increased by adding a third element to the SbTe binary system, the stability of the amorphous state is improved, and the erasing speed is further increased. However, the rewriting performance at the time of one-beam overwriting is not shown, and the number of repetitions of writing and erasing is 1,000, which is insufficient for the characteristics as a rewritable medium.

Japanese Patent Laid-Open Publication No. 3-41635 discloses that
Al-Cr has been proposed as a reflective layer of an optical information recording medium having a Te-Ge-Sb alloy thin film as a recording layer.
Since the Te-Ge-Sb alloy thin film has an extremely high crystallization rate, rapid cooling of the recording layer is required to make the Te-Ge-Sb alloy thin-film. Al diffuses heat at a sufficient rate and gives high reflectance, but there is a problem that crystal grains grow over time and noise increases during reproduction. Therefore, Cr is added to Al to suppress the growth of crystal grains due to the heat history, thereby improving the overwrite performance. However, the above publication states that AgI
No specific study has been made on the rewriting performance of the nSbTe recording layer during one-beam overwriting.

[0006]

The reflective layer made of Al-Cr greatly contributes to the improvement of the overwrite performance repeatedly. However, in order to rapidly cool the AgInSbTe-based recording film from the molten state to make it amorphous, the reflective layer is made of Al-Cr. It is necessary to considerably increase the thickness of the Cr reflection layer. In this case, Al-C
Not only does the cost of the material required for forming the r-reflection layer increase, but the time required for forming the film also increases, which causes a problem of lowering the production efficiency. The present invention focuses on the problems described above, and has been made in order to effectively solve the problems. The purpose of the present invention is to provide a high sensitivity and durability without increasing the thickness of the reflective layer. It is an object of the present invention to provide a phase change type optical disk capable of improving the number of overwrites by improving the number of overwrites.

[0007]

Means for Solving the Problems The present invention has been made to solve the above problems, and a first invention is as follows.
A first dielectric layer 2, a recording layer 3, a second dielectric layer 4, and a reflection / radiation layer 5 are sequentially laminated on a substrate 1, and the arrangement of atoms constituting the recording layer 3 changes by light irradiation. An optical information recording medium 10 on which information is recorded and erased, wherein the reflective heat radiation layer 5 is mainly composed of Ag,
1, Au, Cu, Co, Ni, Ti, V, Mo, Mn,
Pt, Si, Nb, Fe, Ta, Hf, Ga, Pd, B
The optical information recording medium, which is an alloy layer containing at least one element selected from i, In, W, and Zr, according to a second aspect of the present invention, wherein the reflective heat dissipation layer 5 is composed mainly of Ag,
Ag1-aMa (M is Al, Au, Cu, C
o, Ni, Ti, V, Mo, Mn, Pt, Si, Nb,
Fe, Ta, Hf, Ga, Pd, Bi, In, W, Zr
At least one element selected from the group consisting of
Satisfying 01 ≦ a ≦ 0.05 (sum of atomic ratios of a: M),
3. The optical information recording medium according to claim 1, wherein the thickness is 60 nm or more and 150 nm or less, wherein the recording layer is made of Ag, In, Sb, Te, and Ag _w In _x
Sb _y when the Te _z, the optical information recording medium 0.03 ≦ w ≦ 0.08 0.03 ≦ x ≦ 0.08 0.56 ≦ y of claim 1 wherein the composition satisfies the following composition formula ≦ 0.65 0.26 ≦ z ≦ 0.33 0.06 ≦ w + x ≦ 0.16 w + x + y + z = 1 (w: atomic ratio of Ag, x: atomic ratio of In, y: atomic ratio of Sb, z: Te Atomic ratio).

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical information recording medium of the present invention will be described below in detail. First, the recording material will be described.

【Example】

[0009] The recording material of the present invention can be made of Ag, In, Sb, which can take at least two states of a crystalline state and an amorphous state.
This is a phase change type optical recording material made of Te. In the crystal state that is the erased state, a single crystal phase of Ag, In, Sb, and Te or a crystal phase composed of a combination of two or more elements is formed. The crystal state is not limited to a single phase, and two or more crystal phases may coexist. In the amorphous state, which is a recording state, an X-ray diffraction pattern is not shown, but a short-range order may be locally present, and a regular electron beam diffraction pattern may be shown.

In addition, the recording layer of the present invention can provide excellent repetition durability and high-density recording as compared with the conventional recording layer even when recording, erasing, or rewriting by overwriting is repeated. Further, since a higher degree of modulation can be obtained as compared with the conventional recording layer, jitter during high-density recording / reproduction is suppressed and high performance is achieved. In particular, the average composition in the thickness direction of the recording layer is preferably a composition represented by the following composition formula because of excellent repetitive overwrite performance. Formula _{Ag w In x Sb y Te z} 0.03 ≦ w ≦ 0.08 0.03 ≦ x ≦ 0.08 0.56 ≦ y ≦ 0.65 0.26 ≦ z ≦ 0.33 0.06 ≦ w + x ≦ 0.16 w + x + y + z = 1 (w: atomic ratio of Ag, atomic ratio of x: In, atomic ratio of y: Sb, atomic ratio of z: Te)

As is clear from this composition formula, the Sb content strongly controls the crystallization speed of the recording layer, and the crystallization speed increases as the Sb content increases, and it is necessary to increase the transfer speed. it can. In addition, since it is a Te-based alloy containing Sb as a component, it is also excellent in oxidation resistance. However, S
If the amount of b is excessive, the overwrite performance is repeatedly reduced, and if the amount of Sb is excessive, the film becomes crystalline immediately after the film formation, and exhibits a high reflectance. If the contents of Ag, In and Te are excessive, the recording sensitivity is reduced, and the reversible change from amorphous to crystalline and back to amorphous is not exhibited. No longer exhibits an irreversible phase change from to crystals.

A typical layer structure of the optical disk according to the present invention is (A) a laminate of a transparent substrate / first dielectric layer / recording layer / second dielectric layer, or (A) a transparent substrate / first dielectric layer. It is composed of a laminate of a body layer / recording layer / second dielectric layer / reflection layer (here, the laser beam enters from the lower surface of the substrate). See FIG.
However, the configuration of the optical disk of the present invention is not limited to this. SiO, SiO ₂ , ZnO, SnO ₂ , Al ₂ O ₃ , and Ti are formed on the reflective layer within a range that does not impair the effects of the present invention.
Metal oxides such as O ₂ , In ₂ O ₃ , MgO, ZrO ₂ , Si
_{3 N 4, AlN, TiN,} BN, ZrN, nitrides such as _{GeN, ZnS, In 2 S 3} , TaS sulfides such as _4, Si
A protective layer such as a carbide such as C, TaC, B4C, WC, TiC, and ZrC, a resin layer such as an ultraviolet curable resin, and an adhesive layer for bonding to another substrate may be provided.
No reflective layer is provided for applications where recording sensitivity is important (A)
In the case where recording is performed at a high recording density, or in an application in which repetition durability of recording is emphasized, the configuration (a) in which a reflective layer is provided is preferable.

FIG. 1 is a diagram for explaining a sectional structure of an embodiment of the optical disk according to the present invention. As shown in FIG. 1, an optical disc 10 according to the present invention has a first dielectric layer 2, a recording layer 3, a second dielectric layer 4, a reflective layer 5,
The protective layer 6 is sequentially laminated.

The dielectric layer of the present invention (first and second dielectric layers)
The effects of protecting the substrate 1 and the recording layer 3 from heat, such as preventing the substrate 1 and the recording layer 3 from being deformed by heat and deteriorating the recording characteristics during recording, and the optical interference effect, This has the effect of improving the signal contrast during reproduction. Further, there is an effect that the crystallization of the recording layer 3 is promoted and the erasing rate is improved. As the dielectric layers 2 and 4, Zn
There are inorganic thin films such as S, SiO ₂ , Si ₃ N ₄ and Al ₂ O ₃ . In particular, a thin film of a metal or semiconductor oxide such as Si, Ge, Al, Ti, Zr, or Ta; a thin film of a metal or semiconductor nitride such as Si, Ge, or Al;
Thin films of metals such as Hf and Si or carbides of semiconductors,
Thin films of sulfides of metals or semiconductors such as ZnS, In ₂ S ₃ , TaS ₄ , and GeS ₂ , and films of a mixture of two or more of these compounds are preferable because of high heat resistance and chemical stability. . Further, it is preferable that there is no diffusion of atoms constituting the dielectric layer into the recording layer 3. These oxides,
Sulfides, nitrides, and carbides do not necessarily need to have a stoichiometric composition, and it is effective to control the composition for controlling the refractive index and the like, or to use a mixture. A mixture of these and a fluoride such as MgF ₂ is also preferable because the residual stress of the film is small. In particular, a mixed film of ZnS and SiO ₂ is preferable because deterioration of recording sensitivity, C / N, erasure rate, and the like hardly occurs even when recording and erasing are repeated.

The thickness of the first and second dielectric layers 2 and 4 is about 10 to 500 nm. The first dielectric layer 2 is preferably 50 to 300 nm because the first dielectric layer 2 does not easily peel off from the substrate 1 or the recording layer 3 and does not easily cause defects such as cracks. The second dielectric layer 4 has a recording characteristic such as C / N and an erasing rate, and is capable of being stably rewritten many times.
nm is preferred. The first dielectric layer 2 and the second dielectric layer 4
They may be composed of different compounds instead of the same.

The thickness of the recording layer 3 of the present invention is not particularly limited, but is 10 to 100 nm. The reasons are as follows. When the thickness of the recording layer is 10 nm or less, the difference between the reflectance in a crystalline state and the reflectance in an amorphous or microcrystalline state, that is, a sufficient degree of modulation cannot be obtained, and a large reproduction signal intensity cannot be obtained. . Also, if the thickness of the recording layer 3 is 1
If the thickness is more than 00 nm, the heat capacity of the recording layer 3 is large, so that crystallization is not completely performed within the laser beam irradiation time (there is no erased), or it is not sufficiently amorphous at the time of recording and recrystallized. And the deterioration of recording / erasing is caused.

Further, when the thickness of the recording layer 3 is 40 nm or more, when direct overwriting (DOW) is repeated, mass transfer occurs in the recording mark, and as a result, the thickness of the recording layer fluctuates, and recording and erasing is performed with overpower. Is performed, the repetition characteristics deteriorate. Therefore, the recording layer 3 of the present invention
Is particularly high in recording and erasing sensitivities, and can be recorded and erased many times.
It is preferable to set the following.

The material of the reflection layer 5 of the present invention is mainly composed of Ag having light reflectivity, and Al, Au, Cu, C
o, Ni, Ti, V, Mo, Mn, Pt, Si, Nb,
Fe, Ta, Hf, Ga, Pd, Bi, In, W, Zr
An alloy containing at least one additional element selected from the group consisting of: An alloy containing Ag as a main component is preferable because it has high light reflectivity and high thermal conductivity. As an example of the above-mentioned alloy, Ag1-aMa (M is Al, Au,
Cu, Co, Ni, Ti, V, Mo, Mn, Pt, S
i, Nb, Fe, Ta, Hf, Ga, Pd, Bi, I
It is preferable that at least one element selected from n, W, and Zr) and its composition satisfy 0.01 ≦ a ≦ 0.05 (total atomic ratio of a: M). Further, the number of elements constituting M is preferably 4 or less in consideration of manufacturing margin and cost, and more preferably 2 or less from the viewpoint of obtaining better corrosion resistance and repetition performance.

Further, since the recording sensitivity is high and recording and erasing can be performed many times, the heat conductivity of the reflective layer 5 made of the alloy containing Ag as a main component should be 320 W / m · k or more. Is preferred. When the thermal conductivity of the alloy reflective layer 5 is 320 W / m · k or less, the read signal intensity tends to deteriorate when recording and erasing are performed many times.

The thickness of the reflection layer 5 is approximately 60 n
m or more and 150 nm or less. The thickness of the reflection layer 5 is 6
When the thickness is less than 0 nm, the thermal diffusion of the recording layer 3 is insufficient and the erasing characteristics are deteriorated. When the thickness of the reflective layer 5 is 150 nm or more, the recording sensitivity is significantly deteriorated, and the recording / erasing characteristics are deteriorated. In particular, it is preferable to constitute the main part of the optical disk from 60 nm or more and 150 nm or less because the recording sensitivity is high, single-beam overwriting is possible at high speed, and the erasing rate is large and the erasing characteristics are good.

As the material of the substrate 1 of the present invention, various transparent synthetic resins, transparent glass and the like can be used. In particular, a light-transmitting substrate having a groove with a groove pitch of 0.74 to 1.48 μm is preferable. 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,
Examples thereof include polymethyl methacrylate, polyolefin resin, epoxy resin, and polyimide resin. In particular,
Polycarbonate resins are preferred because they have low optical birefringence, low hygroscopicity, and are easy to mold. In order to further improve the recording density, a so-called table reading may be performed through a very thin translucent substrate by providing a laminated medium on the substrate. In this case, the opaque substrate is used because the laser beam does not pass through the substrate. Can be used.

The thickness of the substrate 1 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 1 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 using two substrates after forming a recording layer or the like.

As a light source used for recording on the optical disk 10 according to the present invention, it is preferable to use a laser beam, which mainly has a wavelength in the range of 830 nm in the near infrared region to 300 nm in the ultraviolet region. It is also possible to use a light source in which the primary light is shortened in wavelength using a secondary harmonic generation element (SHG element).

The recording of the optical disk 10 according to the present invention is performed by irradiating a recording layer in a crystalline state with a laser beam pulse or the like to form an amorphous (amorphous) recording mark. Conversely, a recording mark in a crystalline state may be formed on the recording layer 3 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. Practically, the recording peak power superimposed on the low-energy erasing power that causes crystallization is applied to the recording layer 3 to overwrite the already recorded recording mark without going through the erasing process.

At this time, the recording laser pulse is divided into a plurality of pulses shorter than the recording mark length. FIG. 2 shows an example of the divided pulse pattern. 3T of 8-16 modulation method (T:
When recording a (channel period) and a 6T mark, it is preferable that the divided pulse pattern has, for example, a waveform as shown in FIG. In the case of a 3T signal, one pulse may be used. The laser power is the recording peak power P
It is modulated by at least two values of 1 and the erase power P2. Furthermore, the laser power P3 between the divided recording pulses or the cooling power P4 after the final pulse may be added and modulated in four values.

The laser power P3 is preferably smaller than 1/2 of the erasing power and a non-zero laser power (P3). However, since it is necessary to apply focus servo and tracking servo, it is preferable that at least the laser power P3 is higher than the reproduction power (usually 0.3 to 1 mW). Usually, the laser power P3 is set to 0.2 mW or more.

By doing so, recrystallization of the recorded mark after melting can be prevented, and the recording power margin can be widened. This effect is reduced when the laser power P3 between the divided pulses is larger than 1/2 of the erasing power P2. For example, when a 6T mark of the 8-16 modulation method is recorded, the division method may be divided into 4 to 6 pulses.
Since the temperature at the leading end of the mark is unlikely to rise, it may be good to make the leading divided pulse two to four times longer than the other divided pulses.

In FIG. 2, the pulse length T1 of the divided pulse
And the interval T2 between the divided pulses is preferably T1 + T2 = T. In addition, it is possible to more effectively prevent the recrystallization of the recording mark when T1 is shorter than T2. That is,
In some cases, it is better to satisfy T1 ≦ T2. However, T1 is 0.
It must be greater than 1T. If it is less than 0.1T, the previously recorded amorphous mark cannot be erased.

Next, a method for manufacturing the optical disk 10 according to the present invention having the above-described configuration will be described. As a method for forming the reflective layer 5, the recording layer 3, the dielectric layers 2, 4 and the like on the substrate 1, a known thin film forming method in a vacuum, for example, a vacuum deposition method (resistance heating type or electron beam type), Examples include an ion plating method and a sputtering method (DC or AC sputtering, reactive sputtering). In particular, the sputtering method is preferable because the composition and the film thickness can be easily controlled. In the sputtering method, for example, the recording layer 3 in a mixed state can be easily formed by simultaneously sputtering each target with a recording material and an additive material. The degree of vacuum before film formation is preferably set to 1 × 10 ⁻⁴ Pa or less. It is preferable to use a batch type film forming apparatus for simultaneously forming a plurality of substrates in a vacuum chamber or a single wafer type film forming apparatus for processing substrates one by one. The thickness of the reflective layer 5, the recording layer 3, the dielectric layers 2 and 4, etc. to be formed is controlled by controlling the power and time of a sputter power supply, or monitoring the deposition state with a quartz vibrating type film thickness meter or the like. Thus, it can be easily performed.

The formation of the reflection layer 5, the recording layer 3, the dielectric layers 2, 4 and the like may be performed while the substrate 1 is fixed, or may be moved or rotated. The substrate 1 is preferably rotated on its own axis because of excellent in-plane uniformity of the film thickness, and more preferably combined with revolution. When the substrate 1 is cooled as required, the amount of warpage can be reduced.

Next, [Example 1] to [Example 11] which are further specific examples of the present invention will be described. However, the present invention is limited to these [Example 1] to [Example 11]. is not. In [Example 1] to [Example 11],
Recording (one-beam overwriting) was performed using an optical disk drive tester (DDU1000) manufactured by Pulstec equipped with a laser diode having a wavelength of 635 nm and an optical lens having an NA of 0.60. The reproduction light power Pr is set to 0.
It was constant at 7 mW regardless of the linear velocity. The completed optical disk was evaluated as follows.

[0032]

Example 1 Evaluation was performed with a random pattern of 8-16 modulation at a linear velocity of 3.5 m / s. The clock period T is
38.2 nanoseconds (ns). Slicing at the center of the amplitude of the playback signal, clock to data jitter cloc
k to data jitter was measured. To detect marks, use a time interval analyzer (TA32, manufactured by Yokogawa Electric Corporation).
0) was used. The medium is 120mm in diameter and 0.6m in thickness
m on a polycarbonate resin substrate. The substrate is
Track pitch 0.74 μm (groove pitch 1.4
8 μm), and groove recording was performed. The groove depth was 30 nm, and the ratio between the groove width and the land width was about 46:54.

The first dielectric layer 2, the recording layer 3, the second dielectric layer 4, and the reflective layer 5 were vacuum-formed in this order by sputtering while rotating the substrate 1 at a planetary speed of 60 revolutions per minute. First, after the inside of the vacuum chamber was evacuated to 6 × 10 ^-5 Pa, 1.6 × 10 ^-1 Pa Ar gas was introduced. S
iO first thickness 210 nm ₂ to the ZnS added 20 mol% on the substrate 1 by RF magnetron sputtering
It was formed as a dielectric layer 2. Then, Ag, In, S
A recording layer 3 was formed by sputtering a single element of 4 elements consisting of b and Te (diameter: 2 inches, thickness: 3 mm) with a DC power supply. Specifically, the composition Ag0.05In
A recording layer 3 having a thickness of 23 nm and a thickness of 0.05Sb0.61Te0.29 was formed. In the composition analysis, the same recording layer
Formed on a silicon substrate with a thickness of
Analyzed by P emission analysis. Further, a second dielectric layer 4 of the same material as that of the first dielectric layer 2 is formed to a thickness of 10 nm, and a three-element single target composed of Ag, Cu, and Pd is formed thereon by DC sputtering to obtain a composition of Ag 0.97 Cu 0. 0
A reflective layer 5 of 2 (atomic ratio) Pd0.01 (atomic ratio) with a thickness of 75 nm was formed.

After removing the optical disk from the vacuum container, an acrylic UV curable resin (XR11 manufactured by Sumitomo Chemical Co., Ltd.) is spin-coated on the reflective layer 5 and cured by UV irradiation to form a protective layer which is a resin layer having a thickness of 10 μm. Form 6,
An optical disk 10 of the present invention was obtained. Furthermore, apply a slow-acting ultraviolet curable resin on the protective film using screen printing,
The optical disk 10 formed in the same manner was bonded and pressed to produce a double-sided disk.

The optical disk 10 thus manufactured is irradiated with a laser beam, a flash lamp, or the like to heat the recording layer 3 to a temperature higher than the crystallization temperature, thereby performing an initialization process. Practically, an initialization device as described in JP-A-7-282475 is used. After the optical disk 10 is mounted on the spindle, the recording layer 3 is heated by irradiating a high-power laser beam to change to a state of high reflectance. The laser beam applied to the optical disc 10 has a beam diameter larger than the track width, and is preferably longer in the radial direction, and simultaneously initializes a plurality of tracks while rotating the optical disc 10. Specifically, the wavelength of the initialization laser light is 780 nm, and the shape of the irradiation beam is a circle having a radius of 120 μm. The optical disk 10 is rotated at a linear velocity of 3 m / s, and the radius is 22.0 mm.
Initialized from. The initialization laser beam has a power of 45.
It was moved at a speed of 30 μm / rotation in the radial direction at 0 mW, and initialization was completed at a radius of 58.0 mm.

Recording was performed from the side of the substrate 1 to a groove portion serving as a guide groove of the phase change recording layer. The groove is convex when viewed from the incident direction of the laser beam. The recording conditions are shown in FIG.
Tf = 0.5T, T1 = 0.3 in the recording strategy shown in FIG.
T, T2 = 0.7T, Tc = 0.6T, peak power (P1) = 13.5 mW, erase power (P2) =
The evaluation was performed at 6.5 mW, bottom power (P3) = 0.5 mW, and cooling power (P4) = 0.5 mW. The clock-to-data jitter of the reproduced signal and the reproduced amplitude (output) I14 of 14T, which is the longest signal, were measured (mV).
The modulation degree is expressed as I14 / I14H, where I14H is the maximum value of the reproduced signal amplitude of the longest signal 14T. It is known that the material of the recording layer 3 moves to reduce the film thickness, or that the I14 signal decreases due to diffusion and incorporation of impurities. FIG. 3 shows the result of the repeated direct overwrite.

In FIG. 3, the term “jitter” refers to an average jitter of%.
The start (LE) and end (T) of the recording mark
E) and the root mean square. The jitter is required to be 10% or less in initial jitter and 12% or less after rewriting 1000 times because it is said that the system is broken if the value exceeds 15%. In addition, assuming that the jitter due to the optical system is large, that is, considering a sufficient margin, the initial jitter is required to be 8% or less, and after rewriting 1000 times, 10% or less. From such a meaning, the initial jitter in the first embodiment is 7.3.
% After rewriting 30,000 times, 8.0% is a good value.

The modulation degree (I14 / I
14H) is 0.68, which is a value higher than the standard value from the initial value.
68 and its decrease is not recognized, and the output (I14) is almost the same as the initial (1150 mV) and shows a substantially constant value (1170 mV), and no decrease in the output due to mass transfer of the recording layer 3 is observed. In the first embodiment,
The modulation degree, the average jitter and the output (I14) did not degrade over 30,000 times. The optical disc of the present invention
It was found that the recording medium had good repetitive recording durability.

[0039]

Example 2 The composition of the recording layer 3 was changed to Ag0.04In0.0
4Sb0.63Te0.29, the first film thickness configuration
210 nm for the dielectric layer 2, 10 nm for the second dielectric layer 4,
Reflective layer 5 of composition Ag0.98Cu0.01Pd0.01
Was set to 70 nm, and the direct overwrite performance was examined in the same manner as in [Example 1] except that the film thickness of the recording layer 3 was changed. At a linear velocity of 7.0 m / s, direct overwriting is possible when the thickness d of the recording layer 3 is in the range of 21 to 27, and the degree of modulation is 0.65. 2. Linear velocity
When the clock frequency was lowered to 5 m / s and the clock frequency to 14.6 MHz, the composition Ag 0.04 In 0.04 Sb 0.63 Te
Direct overwriting was possible when the thickness of the recording layer 3 was 0.29 and the thickness was 15 to 30 nm.

[0040]

Example 3 The composition of the recording layer 3 was changed to Ag0.07In0.0
8Sb0.58Te0.27.
The dielectric layer 2 is 110 nm, the recording layer 3 is 20 nm, the second dielectric layer 4 is 20 nm, and the composition is Ag0.98Cu0.01.
(Atomic ratio) 80 n of reflective layer 5 with Pd0.01 (atomic ratio)
The direct overwrite performance was examined in the same manner as in [Example 1], except that m was changed to m. The substrate 1 used had a plate thickness of 0.6 mm, a groove depth of 65 nm, a land / groove width ratio of 55/45, and a continuous groove with a track pitch of 0.74 μm. Initialization was performed in the same manner as in Example 1. Direct overwriting was possible in the linear velocity range of 3.5 m / s to 7.5 m / s. Next, DV
The evaluation was performed using the strategy specified in the D-RAM standard. An 8-16 modulation random pattern is recorded at a linear velocity of 8.3 m / s, sliced at the center of the amplitude of the reproduced signal, and
Clock to data jitter and modulation were measured. The mark start edge jitter (LE) after overwriting 100 times is 7.7%, and the mark end jitter (T
E) was 7.4%, and the average jitter was 7.6%.
Mark start edge jitter (L
E) is 8.0%, and the mark end jitter (TE) is 8.0%.
4%, average jitter is 8.2%, mark start end jitter (LE) after 10,000 times overwriting is 8.7%, mark end jitter (TE) is 8.4%, average jitter is 8%. .6
%, Indicating good repetition performance. The degree of modulation is 0.1 from the initial recording to after overwriting 10,000 times.
It was maintained at a high value of 65-0.67.

[0041]

Example 4 The composition of the recording layer 3 was changed to Ag0.03In0.0
4Sb0.65Te0.28, the first film thickness configuration
The dielectric layer 2 was 210 nm, the recording layer 3 was 20 nm, the second dielectric layer 4 was 10 nm, and the composition was Ag0.97Cu0.02.
(Atomic ratio) 80 n of reflective layer 5 with Pd0.01 (atomic ratio)
The direct overwrite performance was examined in the same manner as in [Example 1], except that m was changed to m. The substrate 1 used had a plate thickness of 0.6 mm, a groove depth of 65 nm, a land / groove width ratio of 55/45, and a continuous groove with a track pitch of 0.74 μm. Linear velocity from 3.5 m / s to 7.
Direct overwriting was possible in the range of 5 m / s. The mark start jitter (LE) after overwriting 100 times is 7.5%, and the mark end jitter (TE) is
The average jitter was 7.3% and 7.4%. 1000
Start jitter (LE) after overwriting twice
8.1%, mark end jitter (TE) is 8.2%, average jitter is 8.2%, mark start end jitter (LE) after 10,000 times overwriting is 8.8%, mark end jitter (TE) was 8.6%, and the average jitter was 8.7%, indicating good repetition performance. Further, the modulation degree is 0.64-from initial recording to after overwriting 10,000 times.
It was maintained at a high value of 0.67.

[0042]

Example 5 The composition of the recording layer 3 was changed to Ag0.08In0.0
5Sb0.61Te0.26 and the first film thickness
The dielectric layer 2 is 210 nm, the recording layer 3 is 20 nm, the second dielectric layer 4 is 10 nm, and the composition is Ag0.97Cu0.01.
(Atomic ratio) Pd 0.02 (atomic ratio) reflective layer 5 of 80n
The direct overwrite performance was examined in the same manner as in [Example 1], except that m was changed to m. The substrate 1 used had a plate thickness of 0.6 mm, a groove depth of 65 nm, a land / groove width ratio of 55/45, and a continuous groove with a track pitch of 0.74 μm. Linear velocity from 3.5 m / s to 7.
Direct overwriting was possible in the range of 5 m / s. The mark start jitter (LE) after overwriting 100 times is 7.9%, and the mark end jitter (TE) is
The average jitter was 7.7%, and the average jitter was 7.8%. 1000
Start jitter (LE) after overwriting twice
8.3%, mark end jitter (TE) is 8.4%, average jitter is 8.4%, mark start end jitter (LE) after 10,000 times overwriting is 8.6%, mark end jitter (TE) was 8.7%, and the average jitter was 8.7%, indicating good repetition performance. Further, the modulation degree is 0.64-from initial recording to after overwriting 10,000 times.
It was maintained at a high value of 0.66.

[0043]

Example 6 The composition of the recording layer 3 was changed to Ag0.06In0.0
3Sb0.58Te0.33.
The dielectric layer 2 is 210 nm, the recording layer 3 is 20 nm, the second dielectric layer 4 is 10 nm, and the composition is Ag0.98Cu0.01.
(Atomic ratio) 80 n of reflective layer 5 with Pd0.01 (atomic ratio)
The direct overwrite performance was examined in the same manner as in [Example 1], except that m was changed to m. The substrate 1 used had a plate thickness of 0.6 mm, a groove depth of 65 nm, a land / groove width ratio of 55/45, and a continuous groove with a track pitch of 0.74 μm. Linear velocity from 3.5 m / s to 7.
Direct overwriting was possible in the range of 5 m / s. The mark start edge jitter (LE) after overwriting 100 times is 7.8%, and the mark end jitter (TE) is
The average jitter was 7.6%, and the average jitter was 7.8%. 1000
Start jitter (LE) after overwriting twice
8.3%, mark end jitter (TE) is 8.5%, average jitter is 8.4%, mark start end jitter (LE) after 10,000 times of overwriting is 8.9%, mark end jitter (TE) was 9.1% and the average jitter was 9.0%, indicating good repetition performance. Further, the modulation degree is 0.63-from initial recording to after overwriting 10,000 times.
It was maintained at a high value of 0.66.

[0044]

Example 7 The composition of the recording layer 3 was changed to Ag0.04In0.0
8Sb0.56Te0.32.
The dielectric layer 2 is 210 nm, the recording layer 3 is 20 nm, the second dielectric layer 4 is 10 nm, and the composition is Ag0.95Cu0.02.
(Atomic ratio) Pd 0.03 (atomic ratio) reflective layer 5 of 80n
The direct overwrite performance was examined in the same manner as in [Example 1], except that m was changed to m. Linear velocity 3.5
Direct overwriting was possible in the range of m / s to 7.5 m / s. The mark start edge jitter (LE) after overwriting 100 times was 7.8%, the mark end jitter (TE) was 7.9%, and the average jitter was 7.9%. The mark start jitter (LE) after overwriting 1000 times is 8.4%, and the mark end jitter (TE) is
8.7%, average jitter is 8.6%, mark start edge jitter (LE) after 10,000 times overwriting is 9.2%, mark end jitter (TE) is 9.4%, average jitter is ,
9.3%, indicating good repetition performance. Also,
The modulation degree was maintained at a high value of 0.63 to 0.65 from the initial recording to after overwriting 10,000 times.

[0045]

Example 8 The composition of the recording layer 3 was changed to Ag0.04In0.0
4Sb0.63Te0.29, the first film thickness configuration
The dielectric layer 2 was 200 nm, the recording layer 3 was 20 nm, the second dielectric layer 4 was 10 nm, and the composition was Ag0.97Cu0.02.
(Atomic ratio) 80 n of reflective layer 5 with Pd0.01 (atomic ratio)
The direct overwrite performance was examined in the same manner as in [Example 1], except that m was changed to m. The substrate 1 used had a plate thickness of 0.6 mm, a groove depth of 65 nm, a land / groove width ratio of 55/45, and a continuous groove with a track pitch of 0.74 μm. Linear velocity from 3.5 m / s to 7.
Direct overwriting was possible in the range of 5 m / s. The mark start jitter (LE) after overwriting 100 times is 7.5%, and the mark end jitter (TE) is
The average jitter was 7.3% and 7.4%. 1000
Start jitter (LE) after overwriting twice
8.1%, mark end jitter (TE) is 8.2%, average jitter is 8.2%, mark start end jitter (LE) after 10,000 times overwriting is 8.8%, mark end jitter (TE) was 8.6%, and the average jitter was 8.7%, indicating good repetition performance. Further, the modulation degree is 0.64-from initial recording to after overwriting 10,000 times.
It was maintained at a high value of 0.67.

[0046]

Embodiment 9 The first dielectric layer 2 has a thickness of 71 n.
m, the recording layer 3 is 23 nm, the second dielectric layer 4 is 16 nm,
The direct overlay (DOW) performance was examined in the same manner as in [Example 1] to [Example 7] except that the reflective layer 5 was set to 75 nm and the composition of the recording layer was changed.
FIG. 4 shows the results. As is clear from FIG. 4, even if the film thickness of the first dielectric layer 2 is made relatively small in the range of the recording film compositions 1 to 7, that is, in the range of [Example 1] to [Example 7]. Direct overwrite was possible.
(○: Jitter of 11% or less after 10,000 times of DOW), ：: D
9% or less jitter after OW10000 times)

[0047]

Embodiment 10 The composition of the recording layer 3 was Ag 0.04 In 0.
The thickness of the first dielectric layer 2 was 205 nm, the thickness of the recording layer 3 was 20 nm, and the thickness of the second dielectric layer was 20 nm.
The dielectric layer 4 is set to 10 nm, and the composition of the reflective layer 5 is changed to Ag.
Direct overwrite performance was examined in the same manner as in [Example 1], except that 0.99 Pd0.01 (atomic ratio) and the film thickness were 60 nm. Direct overwrite is possible at a linear velocity of 3.5 m / s, and the modulation factor is 0.
64. The average jitter of the mark start jitter (LE) and mark end jitter (TE) after overwriting 1000 times was 12.5%.

[0048]

Embodiment 11 The composition of the recording layer 3 was changed to Ag0.05In0.
The thickness of the first dielectric layer 2 was 205 nm, the thickness of the recording layer 3 was 20 nm, and the thickness of the second dielectric layer was 20 nm.
The dielectric layer 4 is set to 10 nm, and the composition of the reflective layer 5 is changed to Ag.
Direct overwrite performance was examined in the same manner as in [Example 1], except that 0.98 Cu0.01 (atomic ratio), Pd0.01 (atomic ratio), and the film thickness were 60 nm. Direct overwriting was possible at a linear velocity of 3.5 m / s, and the degree of modulation was 0.65. The average jitter of the mark start edge jitter (LE) and mark end jitter (TE) after overwriting 1000 times was 11.8%.

[0049]

Example 12 The composition of the recording layer 3 was changed to Ag0.04In0.
03Sb0.65Te0.28, the first dielectric layer 2 having a thickness of 195 nm, the recording layer 3 having a thickness of 20 nm, and the second
The dielectric layer 4 is set to 10 nm, and the composition of the reflective layer 5 is changed to Ag.
Direct overwrite performance was examined in the same manner as in [Example 1], except that 0.96 Cu 0.02 (atomic ratio), Pd 0.02 (atomic ratio), and the film thickness were 150 nm. Direct overwriting was possible at a linear velocity of 3.5 m / s, and the degree of modulation was 0.64. The average jitter of mark start edge (LE) and mark end jitter (TE) after overwriting 1000 times is 9.3%, and the average of mark start jitter (LE) and mark end jitter (TE) after 10,000 overwrites is The jitter was 10.6%, indicating good repetition performance.

[0050]

According to the optical disk of the present invention having the above-described structure, the recording and erasing operation is stable even when recording and erasing are repeated a large number of times, and good repetitive recording characteristics with little deterioration of characteristics and almost no defects are generated. Is obtained. Further, the optical disk of the present invention can be easily manufactured by the sputtering method, and the reflection layer can be thinned, so that the production efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an optical disc according to the present invention.

FIG. 2 is a diagram showing a divided pulse pattern of a recording laser.

FIG. 3 is a diagram showing an average jitter and a modulation factor when overwriting is repeatedly performed.

FIG. 4 is a diagram showing the relationship between the composition of a recording layer and repeated overwriting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 1st dielectric layer 3 Recording layer 4 2nd dielectric layer 5 Reflection heat dissipation layer 6 Protective layer 10 Optical disk

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Katsunori Oshima 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Japan Victor Company of Japan (72) Junji Kuroda 3--12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Address F-term (reference) in Victor Company of Japan, Ltd. 5D029 MA13 MA27

Claims (3)

[Claims] 1. A first dielectric layer, a recording layer, a second dielectric layer, and a reflective heat radiation layer are sequentially laminated on a substrate, and the arrangement of atoms constituting the recording layer changes by light irradiation. An optical information recording medium on or from which information is recorded and erased, wherein the reflective heat radiation layer has Ag as a main component and Al, Au,
Cu, Co, Ni, Ti, V, Mo, Mn, Pt, S
i, Nb, Fe, Ta, Hf, Ga, Pd, Bi, I
An optical information recording medium, which is an alloy layer containing at least one element selected from n, W, and Zr. 2. The method according to claim 1, wherein the reflective heat radiation layer contains Ag as a main component.
g1-aMa (M is Al, Au, Cu, Co,
Ni, Ti, V, Mo, Mn, Pt, Si, Nb, F
e, at least one element selected from Ta, Hf, Ga, Pd, Bi, In, W, and Zr) having a composition of 0.0
2. The optical information recording medium according to claim 1, wherein 1 ≦ a ≦ 0.05 (the total of the atomic ratios of a: M) is satisfied, and the thickness is 60 nm or more and 150 nm or less. 3. The optical information recording medium according to claim 1, wherein said recording layer is made of Ag, In, Sb, and Te, and when AgwInxSbyTez, the composition satisfies the following composition formula. 0.03 ≦ w ≦ 0.08 0.03 ≦ x ≦ 0.08 0.56 ≦ y ≦ 0.65 0.26 ≦ z ≦ 0.33 0.06 ≦ w + x ≦ 0.16 w + x + y + z = 1 (w : Atomic ratio of Ag, atomic ratio of x: In, atomic ratio of y: Sb, atomic ratio of z: Te)