JP2003094819A - Optical recording medium and sputtering target therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium, which is optimum for an optical recording method for recording and erasing at the high speed range of the rotational linear speed of a disk of 9.6 m/s or higher, a phase-change type optical recording medium, which is optimum for a rewritable phase-change optical disk, and a sputtering target for realizing the object. SOLUTION: In the optical recording medium having at least a phase-change type recording layer on a disk-like substrate, the recording layer is represented by the compositional formula: XαYβZγSbδTeε (wherein X represents Si and/or Ge; Y represents Ag and/or Bi; and Z represents (Ga and/or In) under the condition that respective compositional ratios (in at.%) satisfy the following inequalities: α+β+γ+δ+ε>=98, 0.5<=α<=5, 0.1<=β<=5, 1<=γ<=10, 65<=δ<=80 and 15<=ε<=25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more specifically, it irradiates a laser beam to cause a phase change in a recording layer material to record / reproduce information and rewrite information. And a phase change type information recording medium capable of Further, the present invention relates to a sputtering target for a phase change type optical recording medium, in which a laser beam is irradiated to cause a phase change in a recording layer material, information can be recorded and reproduced, and rewritable optical recording can be performed. It is applied to the manufacture of media.

[0002]

2. Description of the Related Art As one of optical memory media capable of recording, reproducing and erasing information by irradiating a laser beam, there is a so-called phase change recording medium utilizing a transition between a crystalline phase and an amorphous phase or a crystalline phase. well known. In particular, since it is possible to perform overwriting with a single beam, which is difficult with a magneto-optical memory, and the optical system on the drive side is simpler, the research and development has recently become active.

As a typical example of the phase change recording medium, as described in US Pat. No. 3,530,441, Ge-Te, Ge-Te-Sn, Ge-Te-S,
Ge-Se-S, Ge-Se-Sb, Ge-As-S
Examples include so-called chalcogen-based alloy materials such as e, In-Te, Se-Te, and Se-As.

Further, for the purpose of improving stability, high-speed crystallization, etc., a Ge--Te system containing Au (JP-A-61-2196) is used.
92), Sn and Au (JP-A-61-2).
70190), Pd (JP-A-62-194).
(Described in Japanese Patent Publication No. 90) is proposed. Further, for the purpose of improving the repetitive performance of recording / erasing, a material in which the composition ratio of Ge-Te-Se-Sb and Ge-Te-Sb is specified (JP-A-62-73438 and JP-A-63-228433). (Described in the official gazette) is also proposed.

However, none of them can be said to satisfy all of the characteristics required for a phase change type rewritable optical memory medium. In particular, improvement of recording sensitivity and erasing sensitivity, prevention of reduction of erasing ratio due to unerased portion at the time of overwriting, and extension of life of recorded and unrecorded areas are the most important issues to be solved.

Further, Japanese Patent Application Laid-Open No. 63-251290 proposes a recording medium having a recording layer composed of a multi-component compound single layer whose crystal state is substantially ternary or more. Here, a substantially ternary or higher multi-element compound monolayer means a compound having a stoichiometric composition of ternary or higher (for example, In ₃ SbT).
e ₂ ) is supposed to be contained in the recording layer in an amount of 90 atomic% or more. It is said that the recording and erasing characteristics can be improved by using such a recording layer. However, it has drawbacks such as a low erasing ratio and the laser power required for recording and erasing has not been sufficiently reduced.

Furthermore, _{JP-A-1-277338, (Sb a Te 1-} a) 1-Y M Y (0.4 ≦ here
a <0.7, Y ≦ 0.2, M is Ag, Al, A
s, Au, Bi, Cu, Ga, Ge, In, Pb, P
It is at least one selected from the group consisting of t, Se, Si, Sn and Zn. ) Has been proposed an optical recording medium having a recording layer made of an alloy having a composition represented by The basis of this system is Sb ₂ Te ₃ , and excess Sb improves high-speed erasing and repetitive characteristics, and addition of M promotes high-speed erasing. In addition, the erasing rate by DC light is also high. However, this document does not show the erasing rate at the time of overwriting (the results of the study by the present inventors showed that the unerased portion remains), and the recording sensitivity is also insufficient.

Similarly, in JP-A-60-177446, (In _1-X Sb _X ) _1-Y M _Y (0.
55 ≦ X ≦ 0.80, 0 ≦ Y ≦ 0.20, and M is A
u, Ag, Cu, Pd, Pt, Al, Si, Ge, G
It is selected from a, Sn, Te, Se and Bi. ), And in JP-A-63-228433, an alloy of GeTe-Sb ₂ Te ₃ -Sb (excessive) is used for the recording layer, all of which satisfy the characteristics such as sensitivity and erasing ratio. Not something to do.

In addition, JP-A-4-163839 discloses an optical recording medium formed by incorporating a recording thin film into a Te—Ge—Sb alloy containing N.
Japanese Patent Application Laid-Open No. 4-52188 discloses a recording thin film of Te-G.
An optical recording medium formed by containing an e-Se alloy in which at least one of these components is a nitride is described. Japanese Patent Laid-Open No. 4-52189 discloses a recording thin film of Te. An optical recording medium formed by adsorbing N on a —Ge—Se alloy is described.
However, even these optical recording media could not be obtained with sufficient characteristics.

As described above, in the optical recording medium, the recording sensitivity and the erasing sensitivity are improved, the reduction of the erasing ratio due to the unerased portion during overwriting is prevented, and the recording portion is
Prolonging the service life of unrecorded areas is the most important issue to be solved.

On the other hand, with the rapid spread of CDs (compact discs) in recent years, write-once compact discs (CD-Rs) that can be written only once have been developed and have begun to become popular in the market. However, the CD-R cannot be corrected if it fails even once at the time of writing, and the disc becomes unusable and must be discarded. Therefore,
There has been a long-awaited commercialization of a rewritable compact disc that can compensate for the drawback. In 1996, the rewritable compact disc (CD-RW) was developed, and the CD-R
With the spread of W compatible drives, CD-RW media are being replaced by flexible disks.

As an example of research and development that has been carried out up to now, there is a rewritable compact disk using a magneto-optical disk, but it is difficult to overwrite and a CD-RO.
Since there are drawbacks such as difficulty in compatibility with M and CD-R, the practical development of a phase change type optical disk which is theoretically advantageous for ensuring compatibility has been activated.

Examples of research presentations of rewritable compact discs using phase change type optical discs include Furuya (others): Proceedings of the 4th Phase Change Recording Research Symposium Symposium, 70 (1992), Jinno (others): Proceedings of the 4th Phase Change Recording Study Group Symposium, 76 (1992), Kawanishi (others): Proceedings of the 4th Phase Change Recording Study Group Symposium, 82 (1992), T.S. Handa (et a
l): Jpn. J. Appl. Phys. 32 (199
3) 5226, Yoneda (others): Proceedings of the 5th Symposium on Phase Change Records, Symposium, 9 (1993), Tominaga (others):
Proceedings of the 5th Symposium on Phase Change Records, 5
(1993), etc., but none of them sufficiently satisfy the overall performance such as compatibility with CD-R, recording / erasing performance, recording sensitivity, rewritable number of times, number of times of reproduction, and storage stability. It was These drawbacks were largely due to the low erase ratio mainly due to the composition and structure of the recording material.

Under these circumstances, there has been a demand for a phase change type recording material which has a high erasing ratio and is suitable for high sensitivity recording and erasing, and further a high performance rewritable phase change type compact disc. The present inventors have found and proposed AgInSbTe-based recording materials as a means for solving these drawbacks. As a typical example thereof, Japanese Patent Laid-Open No. 4-780
31, JP-A-4-123551, H.S. Iw
asaki (et al): Jpn. J. Appl. P
hys. 31 (1992) 461, Ide (and others): Proceedings of the 3rd Symposium on Phase Change Recording Research Symposium, 102 (1)
991), H.M. Iwasaki (et al): pn.
J. Appl. Phys. 32 (1993) 5241 and the like. Further, JP-A-2000-97761, JP-A-2000-313170, and JP-A-8-2
No. 2644 and the like are listed, but the recording linear velocity can only support up to 8.4 m / sec.

Although it has been already clear that these technologies can obtain a phase change type optical disk having extremely excellent performance, the above-mentioned total performance is completely satisfied, such as ensuring compatibility with the existing optical disk system, and a new Further efforts have been desired in order to complete the manufacturing technology of the phase-change type optical disk that can form a large market.

[0016]

SUMMARY OF THE INVENTION Therefore, the first object of the present invention is to rotate the disk at a linear velocity of 9.6 m / sec.
An object of the present invention is to provide an optical recording medium most suitable for the optical recording method of recording and erasing in the above high speed area. A second object of the present invention is to provide a phase change type optical recording medium most suitable for a rewritable phase change optical disk. A third object of the present invention is to provide a sputtering target that achieves the above object.

[0017]

DISCLOSURE OF THE INVENTION As a result of intensive studies on the improvement of an optical recording medium, the present inventors have found an optical recording medium and a sputtering target for an optical recording medium which meet the above-mentioned object. That is, according to the present invention, (1) "in an optical recording medium having at least a phase change recording layer on a disk-shaped substrate, the recording layer has a composition formula XαYβZγSbδ
Teε (X represents Si and / or Ge, Y represents Ag and / or Bi, and Z represents Ga and / or In), and their composition ratios (at%) satisfy the following relationships. Characteristic optical recording medium:

[0018]

Α + β + γ + δ + ε ≧ 98 0.5 ≦ α ≦ 5 0.1 ≦ β ≦ 5 1 ≦ γ ≦ 10 65 ≦ δ ≦ 80 15 ≦ ε ≦ 25 ”, (2)“ Sb and Te composition ratio δ ” , Ε is 85 <δ + ε <95 ”, and (3)“ at least a first dielectric layer, a recording layer on a disk-shaped substrate, In an optical recording medium in which a second dielectric layer, a metal or alloy layer, and a UV curable resin layer are laminated in this order, the recording layer has a phase change having the composition range described in the item (1) or (2). Optical recording medium comprising a mold recording material ”, (4)“ thickness of the first dielectric layer is 30 to 120 nm, thickness of the recording layer is 12 to 25 nm, and film of the second dielectric layer ” Thickness is 10-35n
m, the film thickness of the metal or alloy layer is 70 to 180 nm, and the optical recording medium according to item (3) above,
(5) "The second dielectric layer is composed of at least two layers, and the layer adjacent to the recording layer is Al, Si, Ta, T
i, Zn, Y, Zr, Nb, V, Mg, Sn, W oxide, sulfide or a mixture of these compounds, and the layer adjacent to the metal or alloy layer is Si, Ti, W, Zr carbide or The optical recording medium according to any one of the items (2) to (4), which is composed of a mixture of these compounds, and (6) "recording linear velocity 9.6 m / sec."
As described above, the optical recording medium according to any one of the above items (2) to (4), which is rewritable at least once, “,” (7) “the metal or alloy layer is 0
Ag containing ~ 4wt% additive, wherein the additive is A
At least one of u, Pt, Pd, Ru, Ti, Cu
The optical recording medium according to any one of the above items (1) to (6), characterized in that the optical recording medium contains an element of a kind ”, (8)
"C in which the metal or alloy layer contains 0 to 4 wt% of additive
u, and the additive is Au, Pt, Pd, Ru, Ti,
An optical recording medium according to any one of the above items (1) to (6), characterized in that it contains at least one element of Ag.

Further, according to the present invention (9), "a constituent element is used in preparing a recording layer of an optical recording medium in which recording and erasing are performed by phase change of a substance responsible for recording, and the constituent elements are compositional formulas XαYβ.
ZγSbδTeε (X is Si and / or Ge, Y is Ag
And / or Bi and Z represent Ga and / or In. )
And a composition ratio (at%) of each of them satisfies the following relationship:

[0020]

Α + β + γ + δ + ε ≧ 98 0.5 ≦ α ≦ 5 0.1 ≦ β ≦ 5 1 ≦ γ ≦ 10 65 ≦ δ ≦ 80 15 ≦ ε ≦ 25 ”, (10)“ Sb and Te composition ratio δ ” , Ε is 85 <δ + ε <95. The sputtering target according to the above item (9) is provided.

The present invention will be described in more detail below. A
A material containing a quaternary phase-change recording material containing g, In, Te, and Sb as a main component has extremely high recording (amorphization) sensitivity / speed, erasing (crystallization) sensitivity / speed, and erasing ratio. Since it is excellent, it is suitable as a material for the recording layer. The composition of the recording layer capable of obtaining good disc characteristics is as described in the above item (1), but in order to obtain even better recording / erasing properties, the requirements shown in the above item (2) must be satisfied. Is desirable. Further, the material containing Sb and Te as the main components of the phase-change type recording material has extremely good recording (amorphization) sensitivity / speed, erasing (crystallization) sensitivity / speed, and erasing ratio, so that the recording layer Suitable as a material. The composition of the recording layer capable of obtaining good disc characteristics at a recording speed of 9.6 m / sec or more is as described in the above item (2).

Ge and Si each have a relatively high melting point as a simple substance and have an effect of suppressing crystallization of a recorded amorphous mark during high temperature storage, and when 0.5 or more, the effect appears.
More preferably, the effect is remarkably exhibited at 1.5 or more. When it is 5 or more, the crystallization temperature becomes too high, so that the initial crystallization is difficult to perform, and more preferably, when it is 4 or less, the initialization is easy and the mass productivity is excellent.

Ag and Bi have the property of becoming a nucleus of crystal growth during crystallization and facilitate initialization,
The content is preferably 0.1 or more, more preferably 0.5 or more. The upper limit value is 5, and if more than 5 is included, high-speed recording cannot be achieved and 9.6 m / s
Overwriting cannot be performed at a recording linear velocity of ec or more.

Sb and Te form an SbTe compound and serve as a base material for determining the basic recording speed of the present invention.
The larger the amount of Fe and the smaller the amount of Te, the shorter time the crystallization becomes possible. In order to enable O / W recording at 9.6 m / sec or more, the Sb amount is preferably 65 or more and Te is preferably 25 or less, more preferably Sb68 or more, Te23.
It is the following. Further, since excessive Sb deteriorates the storage reliability of the mark, it is preferably 80 or less, more preferably 78 or less. When Te is 15 or less, excess Sb remains in the film, which deteriorates recording characteristics and storage reliability, which is not preferable. More preferably, it is 17 or more. Further, Sb + Te substantially determines the reflectance of the phase change recording medium, the contrast between the amorphous mark and the crystallized pit is maintained, the film is not peeled at the time of O / W, and it is suitable for repeated recording characteristics such as jitter and error. Sb + Te is preferably 85 to 95 in order to obtain a reflectance of 15 to 25% with a recording layer film thickness of about 25 nm. It is more preferably 88 to 93.

Ga and In have the effect of promoting crystal growth and the effect of increasing the basic recording linear velocity determined by the amounts of Sb and Te. The effect is required to be 1 or more, more preferably 2.5 or more. When it is 10 or more, initialization becomes difficult, and more preferably 9 or less.

In the present invention, the composition of the recording layer was a value obtained by measuring the recording film by an emission analysis method. In addition, X-ray microanalysis, Rutherford backscattering, Auger electron spectroscopy, fluorescent X-rays were used. Analytical methods such as In that case, it is necessary to carry out a comparative study with the value obtained by the emission analysis method. In addition, in the case of the luminescence analysis method, generally, about ± 5% of the measured value is considered to be an analysis error.

X-ray diffraction or electron diffraction is suitable for observing the substance contained in the recording layer. That is, as a judgment of the crystalline state, the crystalline state is observed when a spot-like pattern or a Debye ring pattern is observed in the electron diffraction image, and the non-crystalline (amorphous) state is observed when a ring pattern or a halo pattern is observed. And The crystallite diameter can be calculated from the half width of the X-ray diffraction peak by Scherrer's formula (that is, B = b +
(Kλ) / (Dcosθ), where B is the degree of spread (angle) of the diffracted light due to scattering, b is a numerical value determined by experiments, K is Scherrer's constant, λ is the wavelength of the X-ray used for diffraction, and D is The crystallite diameter, θ represents the angle of incidence on the crystallite surface. ).

Further, analytical methods such as FT-IR and XPS are effective for analyzing the chemical bonding state in the recording layer, such as oxides and nitrides. The sputtering target produced by the production method of the present invention and the recording layer formed by the film production method have a film thickness of 10 to 50 nm, preferably 12 to 30 nm. When the thickness is less than 10 nm, the light absorption ability is remarkably lowered, and it cannot serve as a recording layer. If it is thicker than 50 nm, it is difficult for a uniform phase change to occur at high speed.

The thin film recording layer was provided by allowing Sb and AgInTe ₂ having a stoichiometric composition having a chalcopyrite structure and / or a zinc blende type structure and / or a composition close thereto to exist in the target. After that, appropriate processing (initialization) is performed, and for example, the proceedings of the 3rd Autumn Phase 1991 Phase Change Recording Study Group Symposium Proceedings p102 and Ja
panese Journal of Applied P
hysics Vol. 32 (1993) pp. 524
1-5247, the microcrystalline phase AgS.
A mixed phase state of bTe ₂ and amorphous phase In—Sb can be obtained. By providing this mixed phase state as the unrecorded state of the recording layer, it becomes possible to obtain an optical recording medium having a high erasing ratio and capable of repeating recording-erasing with low power.

The grain size of the crystallite of AgInTe ₂ having a stoichiometric composition and / or a composition close to it having a chalcopyrite structure and / or a zinc blende type structure is, for example, a main peak obtained by X-ray diffraction after pulverizing a target. (X-ray source C
In the case of u, λ≈1.54〓, it can be calculated from the line width of about 24.1 °. In the calculation, it is necessary to configure the line width with a reference sample having a sufficiently large crystallite grain size. When the particle size of the crystallite of AgInTe ₂ is 45 nm or more, it is difficult to obtain a mixed phase state in which stable recording and erasing can be performed even if appropriate treatment is performed after the thin film recording layer is installed.

Further, other elements and impurities can be added to the recording layer material of the present invention for the purpose of further improving performance and reliability. As an example, Japanese Patent Application No. 4-1488
Elements (B, N, C, P, Si) described in Japanese Patent Publication
Or O, S, Se, Al, Ti, V, Mn, Fe, Co,
Ni, Cu, Zn, Ga, Ge, Sn, Pd, Pt, A
Preferred examples include u and the like. Particularly, when Ge is added, the effect of improving the storage reliability of recorded signals and the number of O / W repetitions is great.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the layer structure of the optical recording medium of the present invention. A first dielectric layer (heat resistant protective layer) (2), a recording layer (3), a second dielectric layer (heat resistant protective layer) (4), and a reflective heat dissipation layer (5) are provided on a substrate (1). Has been. The heat-resistant protective layers (2) and (4) do not necessarily have to be provided on both sides of the recording layer (3), but when the substrate (1) is a material having low heat resistance such as a polycarbonate resin, the heat-resistant protective layer. It is desirable to provide (2). Furthermore, the first and second dielectrics can be a laminate of two or more layers with separated functions.

The material of the substrate (1) is usually glass, ceramics, or resin, and a resin substrate is preferable in terms of moldability and cost. Typical examples of the resin include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin,
Examples thereof include polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, and the like, and polycarbonate resin and acrylic resin are preferable in terms of processability and optical characteristics. Further, the substrate may have a disk shape, a card shape, or a sheet shape.

However, when the optical recording medium of the present invention is applied to a rewritable phase-change optical disk (CD-Rewritable), it is desirable to give the following specific conditions. The condition is that the width of the guide groove (groove) formed in the substrate to be used (so-called half width) is 0.
25-0.65 micron (μm), preferably 0.30
0.55 μm, and the depth of the guide groove is 20 to 60 n
m, preferably 25 to 50 nm.
When the optical recording medium of the present invention is applied to a rewritable optical recording medium compatible with DVD-ROM, it is desirable that the following specific conditions be given. The condition is that the width of the guide groove formed on the substrate to be used is 0.10 to
The thickness is 0.40 μm, preferably 0.15 to 0.35 μm. The depth of the guide groove is 15 to 45 nm, preferably 20
It is about 40 nm. The thickness of the substrate is 0.
55 to 0.65 mm is suitable, and the thickness of the disc after lamination is preferably 1.1 to 1.3 mm. These substrate grooves improve the reproduction compatibility in the DVD-ROM drive. By combining this substrate condition with the above-mentioned recording material and disc layer configuration, it is possible to provide a rewritable phase change optical disc having excellent compatibility.

As a material for the heat-resistant protective layers (2) and (4)
For SiO, SiO_Two, ZnO, SnO_Two, Al_TwoO
_Three, TiO_Two, In_TwoO_Three, MgO, ZrO_TwoSuch as gold
Group oxide, Si_ThreeN_Four, AlN, TiN, BN, ZrN
Such as nitrides, ZnS, In _TwoS_Three, TaS_FourSulfur
Compounds, SiC, TaC, B_FourC, WC, TiC, ZrC
Carbides such as and diamond-like carbon, or it
And mixtures thereof. These materials alone are protective layers
However, it may be a mixture with each other. Well
In addition, a laminated film of them can be formed if necessary.
When using a laminated structure, the thermal conductivity is low on the side in contact with the recording layer.
In addition, the side in contact with the reflective layer has a high reactivity with the reflective layer material.
It is preferably low. However, the heat-resistant protective layer (2),
The melting point of (4) may be higher than that of the recording layer (3).
is necessary. Such heat resistant protective layers (2), (4)
Are various vapor deposition methods, such as vacuum deposition method, sputtering method.
Method, plasma CVD method, photo CVD method, ion plating
Coating method, electron beam evaporation method, etc.
It

The film thickness of the first dielectric layer (heat resistant protective layer) (2) is 30 to 200 nm, preferably 50 to 120.
It is good to set it to nm. If it becomes thinner than 30 nm, it will not function as a heat-resistant protective layer, and on the contrary, it will become 200 nm.
If the thickness is larger than the above range, the sensitivity is lowered and the interfacial peeling is likely to occur. Further, the protective layer may be multi-layered if necessary.

The thickness of the second dielectric layer (heat resistant protective layer) (4) is 10 to 40 nm, preferably 20 to 35 nm.
It is good to say When the thickness is less than 10 nm, the function as the heat resistant protective layer is not fulfilled, and when the thickness is more than 40 nm, interfacial peeling is likely to occur and the repetitive green recording performance is deteriorated. Further, the protective layer may be multi-layered if necessary. In the case of forming multiple layers, the side in contact with the reflective layer is used as a barrier layer for preventing the reaction between the reflective layer and the protective layer in contact with the recording layer, and therefore it is required to be at least 1 nm or more, preferably 2 nm or more depending on the material used.

As the reflection / heat dissipation layer (5), Al, Au,
A metal material such as Ag or Cu, or an alloy thereof can be used. Among them, Al alloy, Ag simple substance and Ag alloy, Cu simple substance and Cu alloy are excellent in cost and environment resistance, and when Al alloy is used as an additive, Ta, T
i, Cr, Si are excellent, and in the case of Ag alloy, A
u, Pt, Pd, Ru, Ti and Cu are excellent. In the case of Cu alloy, Au, Pt, Pd, Ru, Ti,
Ag is excellent. Such a reflective heat dissipation layer (5) can be formed by various vapor deposition methods such as vacuum deposition method, sputtering method, plasma CVD method, photo CVD method, ion plating method and electron beam evaporation method. It is important that the reflection and heat dissipation layer efficiently dissipate heat, and the film thickness is 50 to 200 nm, preferably 70 to 180 nm.
It is good to say If the film thickness is too thick, the heat dissipation efficiency is too good and the sensitivity is poor, and if it is too thin, the sensitivity is good but the repetitive overwrite property is poor. As characteristics, high thermal conductivity, high melting point, good adhesion to the protective layer, and the like are required.

Electromagnetic waves used for processing (initialization), recording, reproducing and erasing the recording layer formed by the sputtering turdat of the present invention include various ones such as laser light, ultraviolet light, visible light, infrared light and microwave. Can be adopted. Especially when mounted on a drive, a small and compact laser diode is the best choice.

[0040]

EXAMPLES The present invention will be specifically described below with reference to examples. However, these examples do not limit the present invention. <Examples 1 to 6 and Comparative Examples 1 to 4> Table 1 shows the composition of the sputtering target and the number of overwrite repetitions (O / W number) when an optical recording medium was produced using them. Optical recording medium has a width of 0.6 μm and a depth of 40 nm
Polycarbonate disk substrate (thickness: 1.2 mm) in which grooves with a track pitch of 1.6 μm are formed
And a first dielectric layer of ZnS.SiO ₂ (thickness 80
nm), recording layer (thickness 18 nm), second dielectric layer (thickness 32 nm) made of ZnS.SiO ₂ , 1.5 wt% T
Reflective heat dissipation layer made of Al alloy containing i (thickness 160n
m) and a UV resin coating layer (thickness 10 μm) were provided to prepare an optical recording medium. The sputtering of the recording layer is 10
Argon gas of sccm is made to flow, and the sputtering pressure is 3 × 1.
It was performed in RF power 500W in the 0 ^-3 torr.

The rotational linear velocity of the disk is 12.0 m / se.
Recording was performed at an optimum linear velocity for each disk at a value of c or higher. An EFM modulation method was used as a signal modulation method, and a laser pulse to be irradiated was made into multiple pulses for recording during laser recording. The wavelength of the semiconductor laser is 780 nm and the numerical aperture of the objective lens is 0.5. The evaluation column of the disk characteristics shows the reflectance and the number of times of O / W after recording of each disk. O /
The x in the W number column indicates that writing was possible once but overwriting was not possible. In addition, defective initialization indicates that uniform initialization could not be performed.

[0042]

[Table 1]

From Table 1, Ag, In, Sb, Te, Ge
Each composition ratio α, β, γ, δ, ε is 0.5 ≦ α ≦
5, 0.1 ≦ β ≦ 5, 1 ≦ γ ≦ 10, 65 ≦ δ ≦ 80,
It can be seen that good disk characteristics are obtained when 15 ≦ ε ≦ 25. Further, as in Comparative Examples 2 and 3, Sb
If + Te (γ + δ) is 85 at% or less, the reflectance is 14%.
Below, the reproduction compatibility in the CD-ROM drive decreases. Further, the repetitive recording characteristics are deteriorated. further,
As in Comparative Example 4, when Sb + Te (γ + δ) is 95% or more, the reflectance becomes too high and a sufficient signal amplitude cannot be obtained, so that the error during reproduction increases. Comparative Example 1
With this composition, uniform initialization could not be performed. The targets used in Examples 1 to 6 and Comparative Examples 1 to 4 were prepared by melting and quenching the raw materials, pulverizing them, and then performing a heat treatment process before sintering the targets.

<Examples 7 to 12, Comparative Examples 5 to 7> Using the target of Example 2, a polycarbonate disk substrate (thickness: 1.2 m) was used as in Examples 1 to 6 and Comparative Examples 1 to 4.
m) is the first dielectric layer (thickness 8) made of ZnS / SiO2.
0 nm), recording layer (thickness 18 nm), ZnS / SiO2
An optical recording medium was prepared using the materials shown in Table 2 for the second dielectric layer (thickness: 32 nm) and the metal or alloy layer used for the reflection / heat dissipation layer (thickness: 160 nm). The reflectance and the degree of modulation in the table are the reflectance and the degree of modulation when recording was performed at the optimum recording linear velocity of each optical recording medium with the optimum power.
The storability was represented by x when an increase in error was observed after storage at 80 ° C. and 85% RH for 300 hours.

[0045]

[Table 2]

From Table 2, pure silver or silver alloy is 0 to 4 wt%.
The additive of Au, Pt, Pd, Ru,
It can be seen that those containing at least one element of Ti and Cu have good overwrite characteristics and storability. Further, pure copper or a copper alloy contains an additive of 0 to 4 wt%, and the additive containing at least one element of Au, Pt, Pd, Ru, Ti, and Ag has good overwrite characteristics and storage stability. Understand

<Examples 13 to 16 and Comparative Examples 8 to 11> Using the target of Example 1, a first dielectric layer (thickness: 80 nm) made of ZnS.SiO2 was formed on a polycarbonate disk substrate (thickness: 1.2 mm). ), Recording layer (thickness 18n
m) and the materials shown in Table 3 were used to fabricate an optical recording medium in which a second dielectric layer, a third dielectric layer, and a reflective heat dissipation layer (thickness 160 nm) made of pure silver were sequentially laminated. The reflectance and the degree of modulation in the table are the reflectance and the degree of modulation when recording was performed at the optimum recording linear velocity of each optical recording medium with the optimum power. Shelf life is 8
Those in which an increase in error was observed after storage at 0 ° C. and 85% RH for 300 hours were represented by x.

[0048]

[Table 3]

From Table 3, when the reflective heat dissipation layer is pure silver or a silver alloy, when the dielectric layer in contact with the reflective heat dissipation layer contains sulfide,
It can be seen that the storage stability is poor, and there is no problem in storage stability with oxides and carbides. This is due to the fact that silver reacts with sulfur contained in the dielectric and sulphurizes.

[0050]

As is apparent from the detailed and specific description above, according to the present invention described in claims 1, 2 and 3, the optical recording for erasing the recording by the phase change of the substance responsible for recording. By adjusting the composition ratio of the constituent elements of the recording layer of the medium, it is possible to provide an optical recording medium having a high linear velocity and excellent overwrite characteristics. Further, according to the present invention described in claim 4, an optical recording medium is provided in which the reflectance is within an appropriate range by optimally adjusting the film thickness of each layer, and which is excellent in overwrite characteristics and drive matching. can do. Further, according to the invention of claim 5, the rewriting is possible at 9.6 m / sec or more, so that the writing and overwriting speed of the optical recording medium is increased, and the data can be written in the peripheral device of the computer. Transfer speed will be faster. Further, according to the present invention as set forth in claims 6, 7, and 8, by selecting the material composition of the reflection / heat dissipation layer of the optical recording medium within an appropriate range, a high reflectance is maintained and an excellent overwrite characteristic is obtained. Further, it is possible to provide an optical recording medium having good storage stability. Further, according to the present invention described in claims 9 and 10, it is possible to provide the optical recording medium according to claims 1 to 8 by setting the composition of the target in an appropriate range.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a layer structure of an optical recording medium of the present invention.

FIG. 2 is a diagram showing the relationship between the amount of Sb + Te and the reflectance of an optical recording medium in the present invention.

[Explanation of symbols]

1 substrate 2 Heat-resistant protective layer (first dielectric layer) 3 recording layers 4 Heat-resistant protective layer (second dielectric layer) 5 Reflective heat dissipation layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shimofuku Hikari             1-3-3 Nakamagome, Ota-ku, Tokyo Stocks             Company Ricoh F-term (reference) 2H111 EA23 FA01 FA11 FA21 FA23                       FB05 FB09 FB12 FB17 FB21                 5D029 JA01 JB45 JC17                 5D121 AA01 EE09

Claims (10)

[Claims] 1. An optical recording medium having at least a phase-change recording layer on a disk-shaped substrate, wherein the recording layer has a composition formula XαYβZγSbδTeε (X is Si and / or G).
e and Y are Ag and / or Bi, Z is Ga and / or In
Represents ), Each composition ratio (at%)
The optical recording medium is characterized by satisfying the following relationship. ## EQU1 ## α + β + γ + δ + ε ≧ 98 0.5 ≦ α ≦ 5 0.1 ≦ β ≦ 5 1 ≦ γ ≦ 10 65 ≦ δ ≦ 80 15 ≦ ε ≦ 25 2. The composition ratio δ, ε of Sb and Te is 85.
The optical recording medium according to claim 1, wherein <δ + ε <95. 3. An optical recording medium in which at least a first dielectric layer, a recording layer, a second dielectric layer, a metal or alloy layer, and a UV curable resin layer are laminated in this order on a disk-shaped substrate. An optical recording medium comprising: a phase change recording material having the composition range according to claim 1 or 2. 4. The film thickness of the first dielectric layer is 30 to 120.
nm, the recording layer has a thickness of 12 to 25 nm, the second dielectric layer has a thickness of 10 to 35 nm, and the metal or alloy layer has a thickness of 70 to
The optical recording medium according to claim 3, wherein the optical recording medium has a thickness of 180 nm. 5. The optical recording medium according to claim 2, which is rewritable at least once at a recording linear velocity of 9.6 m / sec or more. 6. The second dielectric layer comprises at least two layers, and the layer adjacent to the recording layer is made of Al, Si, T.
a, Ti, Zn, Y, Zr, Nb, V, Mg, Sn, W
Of oxides, sulfides or mixtures of these compounds, the layer adjacent to the metal or alloy layer being Si, Ti, W,
6. The optical recording medium according to claim 2, comprising a Zr carbide or a mixture of these compounds. 7. The metal or alloy layer is Ag containing 0 to 4 wt% additive, and the additive is Au, Pt, Pd,
7. The optical recording medium according to claim 1, which contains at least one element selected from Ru, Ti, and Cu. 8. The metal or alloy layer is Cu containing an additive of 0 to 4 wt%, and the additive is Au, Pt, Pd,
7. The optical recording medium according to claim 1, which contains at least one element selected from Ru, Ti, and Ag. 9. A method for producing a recording layer of an optical recording medium, in which recording and erasing are performed by a phase change of a substance responsible for recording,
The constituent elements are the composition formula XαYβZγSbδTeε (X is Si
And / or Ge, Y represents Ag and / or Bi, and Z represents Ga and / or In. ), And the composition ratio (at%) of each satisfies the following relationship. Α + β + γ + δ + ε ≧ 98 0.5 ≦ α ≦ 5 0.1 ≦ β ≦ 5 1 ≦ γ ≦ 10 65 ≦ δ ≦ 80 15 ≦ ε ≦ 25 10. The composition ratio δ, ε of Sb and Te is 8
The sputtering target according to claim 9, wherein 5 <δ + ε <95.