WO2003070479A1 - Optical recording medium and optical recording method - Google Patents

Optical recording medium and optical recording method Download PDF

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Publication number
WO2003070479A1
WO2003070479A1 PCT/JP2003/001307 JP0301307W WO03070479A1 WO 2003070479 A1 WO2003070479 A1 WO 2003070479A1 JP 0301307 W JP0301307 W JP 0301307W WO 03070479 A1 WO03070479 A1 WO 03070479A1
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Prior art keywords
transition metal
recording
optical recording
optical
recording medium
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PCT/JP2003/001307
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French (fr)
Japanese (ja)
Inventor
Akira Kouchiyama
Katsuhisa Aratani
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Sony Corporation
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Publication of WO2003070479A1 publication Critical patent/WO2003070479A1/en

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/251—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising inorganic materials dispersed in an organic matrix

Definitions

  • the present invention relates to an optical recording medium using an inorganic material for a recording layer and an optical recording method.
  • CD-R write-once optical recording medium
  • CD-ROM read-only memory
  • CD-Rs have a smaller quantity than conventional CD-ROMs, which record information by transferring pits and projections on the stamper to the substrate by injection molding or other techniques to form pits. Can be copied at a reasonable price and quickly. Because of these advantages, the demand for CD-R is rapidly increasing with the spread of personal computers in recent years.
  • a typical structure of such a write-once optical recording medium is a recording layer made of an organic dye material on a transparent disk-shaped substrate, a reflective layer made of a metal such as gold, and a resin.
  • a protective layer is laminated in this order.
  • the recording of information on the optical disk is performed by irradiating the optical disk with near-infrared laser light (usually a laser light having a wavelength of about 780 nm). This is done by absorbing the light and locally generating and deforming heat, for example, generating pits and the like.
  • near-infrared laser light usually a laser light having a wavelength of about 780 nm.
  • information is usually reproduced by irradiating the optical disc with laser light having the same wavelength as the recording laser light, and the dye recording layer is heated and deformed (recorded part) and undeformed (recorded part). This is done by detecting the difference in reflectance between
  • DVDR write-once DVD
  • This DVD-R is usually prepared by preparing two disks in which a recording layer composed of an organic dye, a reflective layer, and a protective layer are laminated in this order on a transparent disk-shaped substrate, and these are recorded. This is a structure in which the layers are bonded together with the layers inside, or a structure in which this disk is bonded to a disk-shaped protective substrate having the same shape.
  • the disc-shaped substrate used for DVD-R has a guide groove (pred-loop) for tracking the laser beam irradiated during recording, and the guide groove for the CD-R of 0.74 m to 0.8 zm is provided. It is formed with a narrow groove width of less than half.
  • dye recording layers used in conventional CD-Rs and DVD-Rs are designed to absorb light at the recording wavelength used in conventional systems and deform by heat. It is difficult to obtain a large change in optical characteristics with recording light of 600 nm or less. For this reason, there is a need for the development of a new optical recording medium suitable for a new optical recording method using a recording / reproducing laser having a wavelength of 60 Onm or less, which is different from the conventional one.
  • the recording layer using the conventional dye-based material has a problem that the reflectance is low.
  • the present invention has been proposed to solve such a conventional problem.
  • information can be recorded and reproduced by light having a wavelength of 60 O nm or less, and good recording and reproduction can be performed.
  • An object is to provide an optical recording medium having characteristics.
  • Another object of the present invention is to provide an optical recording method capable of recording information at a higher density. Disclosure of the invention
  • the optical recording medium according to the present invention has been completed based on such findings, and has a substrate and a recording layer formed on the substrate, wherein the recording layer is formed of a transition metal. It contains a complete oxide as a recording material.
  • the optical recording method according to the present invention provides recording and reproduction with an optical recording medium having a wavelength of 600 nm or less on an optical recording medium including a substrate and a recording layer containing a transition metal incomplete oxide as a recording material. It is characterized by performing.
  • imperfect oxide of a transition metal refers to a compound that is shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the possible valence of the transition metal, that is, the imperfect transition metal oxide
  • a compound whose oxygen content is smaller than the oxygen content of a stoichiometric composition corresponding to the possible valence of the transition metal is defined.
  • transition metal atom having a crystal structure When multiple types of transition metals are included, it is considered that one type of transition metal atom having a crystal structure is partially replaced by another type of transition metal atom. It is determined whether or not the oxide is incomplete depending on whether the oxygen content is insufficient for the stoichiometric composition.
  • the incomplete oxide of the transition metal used in the recording layer of the optical recording medium of the present invention shows absorption for light having a wavelength of 600 nm or less, and is irradiated with light having a wavelength of 600 nm or less as recording light. Thereby, a change in the optical constant and a change in Z or shape can be obtained such that the difference in reflectance between the recorded portion and the unrecorded portion is sufficient.
  • the incomplete oxide of the transition metal is a material having a higher reflectivity for light having a wavelength of 600 nm or less than the organic dye material, and enables more sensitive reproduction.
  • FIG. 1 is a photograph of an optical disc using an incomplete oxide of W as a recording material, observed by SEM. BEST MODE FOR CARRYING OUT THE INVENTION
  • An optical disc to which the present invention is applied basically has a substrate and a recording layer formed on the substrate.
  • the recording layer of the present invention contains an incomplete oxide of a transition metal as a recording material.
  • an incomplete oxide of a transition metal is a compound shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the possible valence of the transition metal, that is, the incomplete oxide of the transition metal.
  • a compound whose oxygen content is smaller than the oxygen content of the stoichiometric composition corresponding to the possible valence of the transition metal is defined.
  • transition metals can form oxides having different valences with one element.In this case, however, the stoichiometric composition corresponding to the possible valences of the transition metal causes the actual oxygen content to change. The case where the amount is insufficient is within the scope of the present invention.
  • the above-mentioned trivalent oxide (Mo3) is the most stable, but in addition, monovalent oxide (Mo3) 6
  • incomplete oxides of transition metals exhibit metallic luster in an unrecorded state, and have a wavelength of 600 nm or less. It shows absorption for light, that is, it shows high reflectance.
  • the imperfect oxide of the transition metal undergoes a change in the optical constant and a change in Z or shape when irradiated with recording light of a predetermined power having a wavelength of 600 nm or less. descend. In other words, the reflectance decreases at the recording portion, and the recording becomes apparently transparent.
  • the incomplete oxide of the transition metal can be used, for example, as a write-once optical recording material.
  • the incomplete oxide of the transition metal has a clear boundary between the recorded portion and the unrecorded portion due to the small size of the molecule.
  • transition metals include Ti, V, Cr, Mn, Fe, Nb, Cu, Ni, Co, Mo, Ta, W, Zr, Ru, Ag And the like.
  • Mo, W, Cr, Fe, and Nb are preferably used, and Mo and W are particularly used from the viewpoint that the optical change due to irradiation with light having a wavelength of 600 nm or less is large. Is preferred.
  • Incomplete oxides of transition metals include, in addition to incomplete oxides of one type of transition metal, those added with a second transition metal, those added with multiple types of transition metals, and those other than transition metals Any of the elements to which other elements are added are included in the scope of the present invention.
  • At least one of the above-mentioned transition metals, A 1 and the like can be used. In this case, it is considered that a part of one transition metal atom in the crystal structure is partially replaced by another transition metal atom. Whether or not it is an incomplete oxide will be determined based on whether or not the content is insufficient.
  • the crystal grains of the incomplete oxide of the transition metal become small, so that the boundary between the recorded portion and the unrecorded portion becomes clearer. More specifically, noise characteristics are improved by adding the above elements to the transition metal incomplete oxide at 10 atomic% or more, and good reproduction signals can be obtained by adding 20 atomic% or more. Can be. However, if the proportion of the added element in the incomplete oxide of the transition metal is too high, the optical change amount becomes small, so that a sufficient SN ratio as a recording medium cannot be obtained, and the modulation degree cannot be obtained. Disadvantages occur. Therefore, the ratio is preferably 50 atomic% or less.
  • a conventionally known material used for an ordinary optical recording medium can be used, and for example, plastics such as a polystyrene resin, an acrylic polymer, and glass are preferable.
  • the degree of oxidation of the incomplete oxide of the transition metal can be controlled by changing the oxygen gas concentration in the vacuum atmosphere.
  • sputtering multiple substrates can be obtained by constantly rotating the substrate on different types of sputtering targets. Mix transition metals of different types. The mixing ratio is controlled by changing the input power of each sputter.
  • a target composed of an incomplete oxide of a transition metal containing a desired amount of oxygen in advance is used.
  • a recording layer made of an incomplete oxide of a transition metal can be similarly formed.
  • a recording layer made of an incomplete oxide of a transition metal can be easily formed by a vapor deposition method other than the sputtering method.
  • the recording layer uses an incomplete oxide of a transition metal as a recording material. Irradiation forms a pit (recorded portion), causing a difference in optical characteristics between the pit and the unrecorded portion.
  • the optical disk on which the pits are recorded is irradiated with reproduction light having a wavelength of 600 nm or less
  • the pits, which are the recording portions transmit the reproduction light and exhibit a low reflectance
  • the pits, which are the recording portions exhibit low reflectance. Since the original optical properties of imperfect oxides of transition metals are maintained, A sufficient reflectance is obtained. By detecting the difference in the light reflectance, the information signal can be reproduced.
  • the optical recording medium using the incomplete oxide of the transition metal for the recording layer can use short-wavelength light having a wavelength of 600 nm or less for recording and reproduction, and has excellent recording and reproduction characteristics. Is obtained. Therefore, it is possible to provide a new optical recording method for achieving higher density recording.
  • the present invention is not particularly limited to a detailed structure as long as the optical recording medium includes a substrate and a recording layer.
  • a substrate, a recording layer, and a protective layer may be provided in this order, and a reflective layer for supplementing reflectance may be provided on the recording layer.
  • an intermediate layer for adjusting recording / reproducing characteristics may be added to the upper surface and the Z or lower surface of the recording layer.
  • a disc having at least two substrates and a recording layer may be bonded to each other to form a two-layer structure, a structure in which this disc is bonded to a disk-shaped protective substrate having the same shape, or a multilayer structure. Is also possible.
  • the present invention is not limited to a structure in which recording and reproduction are performed by irradiating a laser beam from the substrate side, and a structure in which a thin protective layer formed on a recording layer is used as a light transmitting layer may be used.
  • An optical disk was actually manufactured in order to confirm the effects of the present invention, and recording and reproduction were performed.
  • an optical disk was obtained by uniformly forming a recording layer made of an incomplete oxide of W on a sufficiently smoothed optical disk substrate by a sputtering method.
  • sputtering was performed in a mixed atmosphere of argon and oxygen using a sputtering target consisting of a simple substance of W, and the oxygen gas concentration was changed to remove incomplete oxides of W.
  • the degree of oxidation was controlled.
  • the obtained optical disk was set in an optical disk recording / reproducing apparatus using a GaN laser diode having a wavelength of 405 nm as a light source, and the irradiation power was higher than that which caused an irreversible change in the recording layer.
  • the recording light was irradiated to form a pit.
  • pits of different sizes were formed by changing the recording power or pulse width of the recording light.
  • a clear pit pattern was formed as shown in Fig. 1.
  • the width and length of the pit after recording varied with the power and pulse width of the recording light source. For example, a short and narrow pit can be formed by lowering the recording power. More specifically, the pit formed in the leftmost column in Fig. 1 has a width and length of 0.25 m, both of which are smaller than the pit width of a conventional optical disk. It becomes fine.
  • an incomplete oxide of a transition metal as a recording material, recording and reproduction can be performed with light having a wavelength of 600 nm or less, and good recording and reproduction can be performed.
  • An optical recording medium having characteristics can be provided.
  • optical recording medium of the present invention by using the optical recording medium of the present invention, light having a short wavelength of 600 nm or less can be used for recording and reproduction, and good recording and reproduction characteristics can be obtained. It is possible to provide a new optical recording method for realizing density recording.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Mathematical Physics (AREA)
  • Thermal Transfer Or Thermal Recording In General (AREA)
  • Optical Record Carriers And Manufacture Thereof (AREA)
  • Optical Recording Or Reproduction (AREA)

Abstract

An optical recording medium for recording/reproducing information with a light having a wavelength of 600 nm or less. The medium has favorable recording/reproducing characteristics and comprises a substrate and a recording layer formed on the substrate and containing a recording material of a transition metal incomplete oxide. Information is recorded/reproduced on/from such an optical recording medium of such a structure with a light having a wavelength of 600 nm or less. An optical recording method for recording information at higher density.

Description

明細書 光記録媒体及び光記録方法 技術分野  Description Optical recording medium and optical recording method
本発明は、 記録層に無機材料を用いる光記録媒体及び光記録方 法に関する。 背景技術  The present invention relates to an optical recording medium using an inorganic material for a recording layer and an optical recording method. Background art
従来から、 例えば追記型コンパク トディスク （登録商標） （ C D— R ) 等の 1回限り情報の記録が可能な追記型光記録媒体が広 く知られている。 これら C D— Rは、 射出成形等の手法でスタン パの凹凸パ夕一ンを基板に転写してピッ トを形成することによ り情報を記録する従来の C D _ R O Mに比べて、 少ない数量を手 頃な価格でしかも迅速に複製することが可能である。 このような 利点を有することから、 近年のパーソナルコンピュータ等の普及 に伴って、 C D— Rの需要は急激に増大している。  2. Description of the Related Art A write-once optical recording medium, such as a write-once compact disc (registered trademark) (CD-R), on which information can be recorded only once, has been widely known. These CD-Rs have a smaller quantity than conventional CD-ROMs, which record information by transferring pits and projections on the stamper to the substrate by injection molding or other techniques to form pits. Can be copied at a reasonable price and quickly. Because of these advantages, the demand for CD-R is rapidly increasing with the spread of personal computers in recent years.
このような追記型光記録媒体の代表的な構造としては、 透明な 円盤状の基板上に有機色素系材料等からなる記録層と、 金等の金 属からなる反射層と、 樹脂等からなる保護層とをこの順に積層し たものが挙げられる。  A typical structure of such a write-once optical recording medium is a recording layer made of an organic dye material on a transparent disk-shaped substrate, a reflective layer made of a metal such as gold, and a resin. One in which a protective layer is laminated in this order is exemplified.
そしてこの光ディスクへの情報の記録は、 近赤外光のレーザ光 (通常は波長 7 8 0 n m付近のレーザ光である。） を光ディスク に照射することにより行われ、 色素記録層の照射部分がその光を 吸収して局所的に発熱変形し、 例えばピッ ト等を生成することに より行われる。 一方、 情報の再生は、 通常、 記録用のレーザ光と同じ波長のレ —ザ光を光ディスクに照射して、 色素記録層が発熱変形した部位 (記録部分） と変形していない部位 （未記録部分） との反射率の 違いを検出することにより行われる。 The recording of information on the optical disk is performed by irradiating the optical disk with near-infrared laser light (usually a laser light having a wavelength of about 780 nm). This is done by absorbing the light and locally generating and deforming heat, for example, generating pits and the like. On the other hand, information is usually reproduced by irradiating the optical disc with laser light having the same wavelength as the recording laser light, and the dye recording layer is heated and deformed (recorded part) and undeformed (recorded part). This is done by detecting the difference in reflectance between
また、 最近では、 C D— Rより も高密度の記録が可能な媒体と して、 追記型 D VD、 いわゆる D V D— Rと称される光ディスク が提案され、 実用化されている。 この D VD— Rは、 通常、 透明 な円盤状の基板上に有機色素からなる記録層と、 反射層と、 保護 層とをこの順に積層してなるディスクを 2枚用意し、 これらを記 録層を内側にして貼り合わせてなる構造、 又はこのディスクと同 じ形状の円盤状保護基板とを貼り合わせてなる構造である。  Recently, as a medium capable of recording at a higher density than CD-R, an optical disc called a write-once DVD, so-called DVDR, has been proposed and put into practical use. This DVD-R is usually prepared by preparing two disks in which a recording layer composed of an organic dye, a reflective layer, and a protective layer are laminated in this order on a transparent disk-shaped substrate, and these are recorded. This is a structure in which the layers are bonded together with the layers inside, or a structure in which this disk is bonded to a disk-shaped protective substrate having the same shape.
D V D— Rに用いられる円盤状の基板には、 記録時に照射され るレーザ光を トラッキングするための案内溝（プレダループ）が、 0. 7 4 m〜 0. 8 z mという C D— Rの案内溝の半分以下の 狭い溝幅で形成されている。  The disc-shaped substrate used for DVD-R has a guide groove (pred-loop) for tracking the laser beam irradiated during recording, and the guide groove for the CD-R of 0.74 m to 0.8 zm is provided. It is formed with a narrow groove width of less than half.
この D VD— Rでは、 情報の記録及び再生は、 可視光領域のレ —ザ光 （通常は 6 3 0 n m〜 6 8 0 n mの範囲の波長のレーザ 光） を光ディスクに照射することにより行われており、 このよう な C D— Rより短い波長の光で記録を行う ことにで、 より高密度 での記録を可能としている。  In this DVDR, information is recorded and reproduced by irradiating the optical disk with laser light in the visible light region (usually laser light having a wavelength in the range of 60 nm to 680 nm). By recording with light with a shorter wavelength than CD-R, higher density recording is possible.
一般に、 照射するレーザ光のビーム径が小さく絞られているほ ど、 高密度の記録が可能であり、 波長の短いレーザ光ほどビーム 径を小さく絞ることができるとされている。 すなわち、 波長の短 いレーザ光ほど高密度記録に有利である。  Generally, it is said that the smaller the beam diameter of the irradiated laser beam is, the higher the recording density is, and the shorter the wavelength of the laser beam, the smaller the beam diameter can be. That is, a laser beam having a shorter wavelength is more advantageous for high-density recording.
近年のレーザ技術の発展により、 青色レーザ等の短波長レーザ も実用化されている。 このため、 従来の記録波長である 7 8 O n m又は 6 3 0 n mより もさ らに短波長の光で高密度の記録を行 う ことが可能な新規な光情報記録システムの開発が進められて いる。 With the recent development of laser technology, short-wavelength lasers such as blue lasers have also been put into practical use. Therefore, the conventional recording wavelength of 78 On Development of a new optical information recording system capable of performing high-density recording with light having a wavelength shorter than m or 63 nm is underway.
しかしながら、 従来の C D— Rや D V D— Rに用いられる色素 記録層は、 従来のシステムで用いられる記録波長の光を吸収して 発熱変形するように設計されたものであり、 先に述べた波長 6 0 0 n m以下の記録光で大きな光学特性の変化を得ることが困難 である。 このため、 これまでと異なる例えば波長 6 0 O n m以下 の記録再生用レーザを用いる新規な光記録方法に適した、 新規な 光記録媒体の開発が必要とされている。  However, dye recording layers used in conventional CD-Rs and DVD-Rs are designed to absorb light at the recording wavelength used in conventional systems and deform by heat. It is difficult to obtain a large change in optical characteristics with recording light of 600 nm or less. For this reason, there is a need for the development of a new optical recording medium suitable for a new optical recording method using a recording / reproducing laser having a wavelength of 60 Onm or less, which is different from the conventional one.
また、 光記録媒体において望ましい記録再生特性を達成するた めには様々な特性が要求されるが、 特に光学的な特性として光反 射率が重要である。 しかしながら、 従来の色素系材料を用いた記 録層では、 反射率が低いという問題がある。  In addition, various characteristics are required to achieve desirable recording / reproducing characteristics in an optical recording medium, and in particular, light reflectance is important as an optical characteristic. However, the recording layer using the conventional dye-based material has a problem that the reflectance is low.
そこで本発明はこのような従来の問題点を解決するために提 案されたものであり、 例えば波長 6 0 O n m以下の光によって情 報の記録及び再生が可能であり、 且つ良好な記録再生特性を有す る光記録媒体を提供することを目的とする。 また、 本発明の他の 目的は、 より高密度で情報の記録が可能な光記録方法を提供する ことにある。 発明の開示  Therefore, the present invention has been proposed to solve such a conventional problem. For example, information can be recorded and reproduced by light having a wavelength of 60 O nm or less, and good recording and reproduction can be performed. An object is to provide an optical recording medium having characteristics. Another object of the present invention is to provide an optical recording method capable of recording information at a higher density. Disclosure of the invention
上述の目的を達成するために本発明者らが検討を重ねた結果、 遷移金属酸化物の化学量論組成から僅かでも酸素含有量がずれ るとこの酸化物の波長 6 0 0 n m以下の光に対する吸収が突然 大きくなるとともに、 光学特性が変化することを見出した。 本発明に係る光記録媒体は、 このような知見に基づいて完成さ れたものであり、 基板と、 当該基板上に形成された記録層とを有 し、 上記記録層は、 遷移金属の不完全酸化物を記録材料として含 有するこ.とを特徴とする。 As a result of repeated studies by the present inventors to achieve the above object, if the oxygen content deviates even slightly from the stoichiometric composition of the transition metal oxide, light having a wavelength of 600 nm or less of this oxide is obtained. It has been found that the optical properties change as the absorption for GaN suddenly increases. The optical recording medium according to the present invention has been completed based on such findings, and has a substrate and a recording layer formed on the substrate, wherein the recording layer is formed of a transition metal. It contains a complete oxide as a recording material.
また、 本発明に係る光記録方法は、 基板と遷移金属の不完全酸 化物を記録材料として含有する記録層とを備える光記録媒体に 対して、 波長 6 0 0 n m以下の光で記録再生を行う ことを特徴と する。  In addition, the optical recording method according to the present invention provides recording and reproduction with an optical recording medium having a wavelength of 600 nm or less on an optical recording medium including a substrate and a recording layer containing a transition metal incomplete oxide as a recording material. It is characterized by performing.
ここでいう遷移金属の不完全酸化物とは、 遷移金属のとり うる 価数に応じた化学量論組成より酸素含有量が少ない方向にずれ た化合物のこと、 すなわち遷移金属の不完全酸化物における酸素 の含有量が、 上記遷移金属のとり うる価数に応じた化学量論組成 の酸素含有量より小さい化合物のことと定義する。  The term imperfect oxide of a transition metal as used herein refers to a compound that is shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the possible valence of the transition metal, that is, the imperfect transition metal oxide A compound whose oxygen content is smaller than the oxygen content of a stoichiometric composition corresponding to the possible valence of the transition metal is defined.
なお、 複数種類の遷移金属を含む場合には、 結晶構造のある 1 種の遷移金属原子の一部が他の遷移金属原子で置換されたもの と考えられるが、 これら複数種類の遷移金属がとり うる化学量論 組成に対して酸素含有量が不足しているか否かで不完全酸化物 かどうかを判断することとする。  When multiple types of transition metals are included, it is considered that one type of transition metal atom having a crystal structure is partially replaced by another type of transition metal atom. It is determined whether or not the oxide is incomplete depending on whether the oxygen content is insufficient for the stoichiometric composition.
本発明の光記録媒体の記録層に用いられる遷移金属の不完全 酸化物は、 波長 6 0 0 n m以下の光に対する吸収を示すとともに、 この波長 6 0 O n m以下の光が記録光として照射されることに より、 記録部分と未記録部分とで反射率の差が充分となるような 光学定数の変化及び Z又は形状の変化が得られる。 しかも、 遷移 金属の不完全酸化物は、 有機系色素材料に比べて波長 6 0 0 n m 以下の光に対して高い反射率を示す材料であり、 より高感度な再 生を可能とする。 図面の簡単な説明 The incomplete oxide of the transition metal used in the recording layer of the optical recording medium of the present invention shows absorption for light having a wavelength of 600 nm or less, and is irradiated with light having a wavelength of 600 nm or less as recording light. Thereby, a change in the optical constant and a change in Z or shape can be obtained such that the difference in reflectance between the recorded portion and the unrecorded portion is sufficient. Moreover, the incomplete oxide of the transition metal is a material having a higher reflectivity for light having a wavelength of 600 nm or less than the organic dye material, and enables more sensitive reproduction. BRIEF DESCRIPTION OF THE FIGURES
第 1図は、 記録材料として Wの不完全酸化物を用いた光ディス クを、 S E Mにて観察した写真である。 発明を実施するための最良の形態  FIG. 1 is a photograph of an optical disc using an incomplete oxide of W as a recording material, observed by SEM. BEST MODE FOR CARRYING OUT THE INVENTION
以下、 本発明を適用した光記録媒体及び光記録方法について、 図面を参照しながら詳細に説明する。  Hereinafter, an optical recording medium and an optical recording method to which the present invention is applied will be described in detail with reference to the drawings.
本発明を適用した光ディスクは、 基板とこの基板上に形成され る記録層とを基本的な構成として有するものである。  An optical disc to which the present invention is applied basically has a substrate and a recording layer formed on the substrate.
本発明の記録層は、 遷移金属の不完全酸化物を記録材料として 含有する。 こ こで、 遷移金属の不完全酸化物は、 遷移金属のとり うる価数に応じた化学量論組成より酸素含有量が少ない方向に ずれた化合物のこと、 すなわち遷移金属の不完全酸化物における 酸素の含有量が、 上記遷移金属のとり うる価数に応じた化学量論 組成の酸素含有量より小さい化合物のことと定義する。  The recording layer of the present invention contains an incomplete oxide of a transition metal as a recording material. Here, an incomplete oxide of a transition metal is a compound shifted in a direction in which the oxygen content is smaller than the stoichiometric composition corresponding to the possible valence of the transition metal, that is, the incomplete oxide of the transition metal. A compound whose oxygen content is smaller than the oxygen content of the stoichiometric composition corresponding to the possible valence of the transition metal is defined.
例えば、 遷移金属の酸化物として化学式 M O O 3を例に挙げて 説明する。 化学式 M ο〇 3の酸化状態を組成割合 M ο — x O xに 換算すると、 x = 0 . 7 5の場合が完全酸化物であるのに対して、 0 < X < 0 . 7 5で表される場合に化学量論組成より酸素含有量 が不足した不完全酸化物であるといえる。 For example, a description will be given by taking the chemical formula MOO 3 as an example of a transition metal oxide. When the oxidation state of the chemical formula M ο〇 3 is converted into the composition ratio M ο — x O x , the case where x = 0.75 is a complete oxide, whereas the case of 0 <X <0.75 In this case, it can be said that this is an incomplete oxide having an oxygen content deficient from the stoichiometric composition.
また、 遷移金属では 1つの元素が価数の異なる酸化物を形成可 能なものがあるが、 この場合には、 遷移金属のとり うる価数に応 じた化学量論組成より実際の酸素含有量が不足している場合を 本発明の範囲内とする。 例えば M oは、 先に述べた 3価の酸化物 ( M o O 3 ) が最も安定であるが、 その他に 1価の酸化物 （M o 6 Some transition metals can form oxides having different valences with one element.In this case, however, the stoichiometric composition corresponding to the possible valences of the transition metal causes the actual oxygen content to change. The case where the amount is insufficient is within the scope of the present invention. For example, as for Mo, the above-mentioned trivalent oxide (Mo3) is the most stable, but in addition, monovalent oxide (Mo3) 6
〇）も存在し、この場合には組成割合 Μ θ -χ θ χに換算すると、 0 < X < 0. 5の範囲内であるとき化学量論組成より酸素含有量 が不足した不完全酸化物であるといえる。 なお、 遷移金属酸化物 の価数は、 市販の分析装置で分析可能である。 〇) also exists. In this case, when converted to the composition ratio Μθ-χθχ, incomplete oxides whose oxygen content is less than the stoichiometric composition when 0 <X <0.5. You can say that. The valence of the transition metal oxide can be analyzed with a commercially available analyzer.
このような遷移金属の不完全酸化物は、 波長 6 0 0 nm以下で 低い反射率を示す有機系色素材料とは異なり、 未記録状態で金属 光沢を呈しており、 波長 6 0 O n m以下の光に対して吸収を示す、 すなわち高い反射率を示すものである。 そして、 遷移金属の不完 全酸化物は、 波長 6 0 0 n m以下の所定パワーの記録光を照射さ れることで光学定数の変化及び Z又は形状の変化を生じ、 記録部 分における吸収率が低下する。 言い換えると、 記録部分で反射率 が低下して、 見かけ上透明となる。 このように、 記録部分と未記 録部分とで光学特性に差が生じるので、 遷移金属の不完全酸化物 を例えば追記型の光記録材料として利用可能なのである。  Unlike incomplete organic dye materials that exhibit low reflectance at wavelengths of 600 nm or less, such incomplete oxides of transition metals exhibit metallic luster in an unrecorded state, and have a wavelength of 600 nm or less. It shows absorption for light, that is, it shows high reflectance. The imperfect oxide of the transition metal undergoes a change in the optical constant and a change in Z or shape when irradiated with recording light of a predetermined power having a wavelength of 600 nm or less. descend. In other words, the reflectance decreases at the recording portion, and the recording becomes apparently transparent. As described above, since a difference occurs in the optical characteristics between the recorded portion and the unrecorded portion, the incomplete oxide of the transition metal can be used, for example, as a write-once optical recording material.
波長 6 0 O n m以下の光を照射されることで遷移金属の不完 全酸化物の光学特性が変化する理由は定かではないが、 記録部分 における酸素含有量の増加や、 記録部分における結晶相の変化が 生じているためであると考えられる。  It is not clear why the irradiation of light with a wavelength of 60 O nm or less changes the optical properties of the incomplete oxide of the transition metal. It is considered that the change has occurred.
また、 遷移金属の不完全酸化物は、 分子のサイズが小さいため に記録部分と未記録部分との境界が明瞭なものとなる。  In addition, the incomplete oxide of the transition metal has a clear boundary between the recorded portion and the unrecorded portion due to the small size of the molecule.
具体的な遷移金属としては、 T i 、 V、 C r、 M n、 F e、 N b、 C u、 N i 、 C o、 M o、 T a、 W、 Z r、 R u、 A g等が 挙げられる。 この中でも、 M o、 W、 C r、 F e、 N bを用いる ことが好ましく、 波長 6 0 0 n m以下の光の照射による光学的変 化が大きいといった見地から特に M o、 Wを用いることが好まし い。 なお、 遷移金属の不完全酸化物としては、 1種の遷移金属の不 完全酸化物の他に、 第 2の遷移金属を添加したもの、 さらに複数 種類の遷移金属を添加したもの、 遷移金属以外の他の元素が添加 されたもの等のいずれも、 本発明の範囲に含めることにする。 添加される元素としては、 上述した遷移金属、 A 1 等のうち少 なく とも 1種を使用可能である。 この場合、 結晶構造のある 1種 の遷移金属原子の一部が他の遷移金属原子で置換されたものと 考えられるが、 これら複数種類の遷移金属がとり うる化学量論組 成に対して酸素含有量が不足しているか否かで不完全酸化物か どうかを判断することとする。 Specific transition metals include Ti, V, Cr, Mn, Fe, Nb, Cu, Ni, Co, Mo, Ta, W, Zr, Ru, Ag And the like. Of these, Mo, W, Cr, Fe, and Nb are preferably used, and Mo and W are particularly used from the viewpoint that the optical change due to irradiation with light having a wavelength of 600 nm or less is large. Is preferred. Incomplete oxides of transition metals include, in addition to incomplete oxides of one type of transition metal, those added with a second transition metal, those added with multiple types of transition metals, and those other than transition metals Any of the elements to which other elements are added are included in the scope of the present invention. As the element to be added, at least one of the above-mentioned transition metals, A 1 and the like can be used. In this case, it is considered that a part of one transition metal atom in the crystal structure is partially replaced by another transition metal atom. Whether or not it is an incomplete oxide will be determined based on whether or not the content is insufficient.
遷移金属の不完全酸化物へ上述の元素を添加することにより、 遷移金属の不完全酸化物の結晶粒が小さくなるので、 記録部分と 未記録部分との境界部がさ らに明瞭となる。 具体的には、 遷移金 属の不完全酸化物へ上述の元素を 1 0原子％以上添加すること でノイズ特性が改善し、 2 0原子％以上添加することで良好な再 生信号を得ることができる。 ただし、 遷移金属の不完全酸化物に 占める添加元素の割合が高くなりすぎると、 光学的な変化量が小 さくなるので、 記録媒体として充分な S N比が得られない、 変調 度がとれない等の不都合が生じる。 よって、 その割合は 5 0原 子％以下であることが好ましい。  By adding the above-described element to the incomplete oxide of the transition metal, the crystal grains of the incomplete oxide of the transition metal become small, so that the boundary between the recorded portion and the unrecorded portion becomes clearer. More specifically, noise characteristics are improved by adding the above elements to the transition metal incomplete oxide at 10 atomic% or more, and good reproduction signals can be obtained by adding 20 atomic% or more. Can be. However, if the proportion of the added element in the incomplete oxide of the transition metal is too high, the optical change amount becomes small, so that a sufficient SN ratio as a recording medium cannot be obtained, and the modulation degree cannot be obtained. Disadvantages occur. Therefore, the ratio is preferably 50 atomic% or less.
なお、 基板としては、 通常の光記録媒体に用いられる従来公知 の材料を使用可能であり、 例えばポリ力一ポネ一ト、 アクリル系 ポリマー等のプラスチック類やガラス等が好適である。  In addition, as the substrate, a conventionally known material used for an ordinary optical recording medium can be used, and for example, plastics such as a polystyrene resin, an acrylic polymer, and glass are preferable.
次に、 上述の光ディスクを作製する方法について説明する。 最初に、 表面が充分に平滑とされた基板上に、 記録材料である 遷移金属の不完全酸化物を均一に成膜し、 記録層を形成する。 記 雇 307 Next, a method of manufacturing the above optical disk will be described. First, an incomplete oxide of a transition metal as a recording material is uniformly formed on a substrate having a sufficiently smooth surface to form a recording layer. Record Hire 307
8 録層を形成する具体的な手法としては、 例えば遷移金属の単体か らなるスパッタタ一ゲッ トを用いて、 アルゴン及び酸素雰囲気中 でスパッタリ ング法により成膜を行う方法が挙げられる。 この場 合には、 真空雰囲気中の酸素ガス濃度を変えることにより、 遷移 金属の不完全酸化物の酸化度合いを制御できる。 2種類以上の遷 移金属を含む遷移金属の不完全酸化物をスパッタ リ ング法によ り成膜する場合には、 異なる種類のスパッ夕夕一ゲッ ト上で基板 を常に回転させることにより複数種類の遷移金属を混合させる。 混合割合は、 それぞれのスパッ夕投入パワーを変えることにより 制御する。 As a specific method of forming the recording layer, for example, there is a method of forming a film by a sputtering method in an atmosphere of argon and oxygen using a sputter target made of a single transition metal. In this case, the degree of oxidation of the incomplete oxide of the transition metal can be controlled by changing the oxygen gas concentration in the vacuum atmosphere. When depositing incomplete oxides of transition metals, including two or more transition metals, by sputtering, multiple substrates can be obtained by constantly rotating the substrate on different types of sputtering targets. Mix transition metals of different types. The mixing ratio is controlled by changing the input power of each sputter.
また、 先に述べた金属夕一ゲツ トを用いた酸素雰囲気中のスパ ッ夕リ ング法の他、 予め所望量の酸素を含有する遷移金属の不完 全酸化物からなるターゲッ トを用いて通常のアルゴン雰囲気中 でスパッタリ ングを行う ことによつても、 遷移金属の不完全酸化 物からなる記録層を同様に成膜できる。  In addition to the above-described sputtering method in an oxygen atmosphere using a metallic metal target, a target composed of an incomplete oxide of a transition metal containing a desired amount of oxygen in advance is used. By performing sputtering in a normal argon atmosphere, a recording layer made of an incomplete oxide of a transition metal can be similarly formed.
さらに、 スパッタリ ング法の他、 蒸着法によっても遷移金属の 不完全酸化物からなる記録層を容易に成膜可能である。  Further, a recording layer made of an incomplete oxide of a transition metal can be easily formed by a vapor deposition method other than the sputtering method.
このような構成の光ディスクは、 記録層において遷移金属の不 完全酸化物を記録材料として用いているので、 情報を記録する際 には、 波長 6 0 0 n m以下の所定照射パワー以上の記録光を照射 してピッ ト （記録部分） を形成することにより、 ピッ トと未記録 部分との光学特性に差を生じせしめる。  In the optical disk having such a configuration, the recording layer uses an incomplete oxide of a transition metal as a recording material. Irradiation forms a pit (recorded portion), causing a difference in optical characteristics between the pit and the unrecorded portion.
そして、 ピッ トが記録された光ディスクに今度は波長 6 0 0 n m以下の再生光を照射すると、 記録部分であるピッ トにおいては 再生光が透過して低い反射率を示す一方、 未記録部分においては 遷移金属の不完全酸化物本来の光学特性が維持されているので 充分な反射率が得られる。 この光の反射率の違いを検出すること により、 情報信号の再生が可能となるのである。 Then, when the optical disk on which the pits are recorded is irradiated with reproduction light having a wavelength of 600 nm or less, the pits, which are the recording portions, transmit the reproduction light and exhibit a low reflectance, while the pits, which are the recording portions, exhibit low reflectance. Since the original optical properties of imperfect oxides of transition metals are maintained, A sufficient reflectance is obtained. By detecting the difference in the light reflectance, the information signal can be reproduced.
このように、 遷移金属の不完全酸化物を記録層に用いた光記録 媒体は、 波長 6 0 0 n m以下の短波長の光を記録再生に用いるこ とが可能となり、 且つ良好な記録再生特性が得られる。 したがつ て、 さらなる高密度記録を実現する新たな光記録方法を提供する ことが可能となる。  As described above, the optical recording medium using the incomplete oxide of the transition metal for the recording layer can use short-wavelength light having a wavelength of 600 nm or less for recording and reproduction, and has excellent recording and reproduction characteristics. Is obtained. Therefore, it is possible to provide a new optical recording method for achieving higher density recording.
なお、 本発明は、 基板と記録層とを備える光記録媒体であれば 詳しい構造には特に限定されない。 例えば、 基板と記録層とさ ら に保護層とをこの順に備えても良く、 記録層上に反射率を補うた めの反射層が設けられていても良い。 また、 記録層の上面及び Z 又は下面に記録再生特性を調整するための中間層を追加しても 良い。 また、 少なく とも基板と記録層とを備えるディスクを 2枚 貼り合わせて 2層構造とすることや、 このディスクと同じ形状の 円盤状保護基板とを貼り合わせてなる構造や、 さらに多層化する ことも可能である。 また、 本発明は、 基板側からレーザ光を入射 して記録再生を行う構造に限定されず、 記録層上に形成された薄 い保護層を光透過層とする構造であってもよい。  In addition, the present invention is not particularly limited to a detailed structure as long as the optical recording medium includes a substrate and a recording layer. For example, a substrate, a recording layer, and a protective layer may be provided in this order, and a reflective layer for supplementing reflectance may be provided on the recording layer. Further, an intermediate layer for adjusting recording / reproducing characteristics may be added to the upper surface and the Z or lower surface of the recording layer. In addition, a disc having at least two substrates and a recording layer may be bonded to each other to form a two-layer structure, a structure in which this disc is bonded to a disk-shaped protective substrate having the same shape, or a multilayer structure. Is also possible. Further, the present invention is not limited to a structure in which recording and reproduction are performed by irradiating a laser beam from the substrate side, and a structure in which a thin protective layer formed on a recording layer is used as a light transmitting layer may be used.
実施例  Example
本発明の効果を確認すべく実際に光ディスクを作製し、 記録及び 再生を行った。 An optical disk was actually manufactured in order to confirm the effects of the present invention, and recording and reproduction were performed.
先ず、 充分に平滑化された光ディスク基板上に、 スパッタリ ン グ法によ り Wの不完全酸化物からなる記録層を均一に成膜する ことにより、 光ディスクを得た。 このとき、 Wの単体からなるス パッタタ一ゲッ トを用い、 アルゴンと酸素との混合雰囲気中でス パッタリ ングを行い、 酸素ガス濃度を変えて Wの不完全酸化物の 酸化度合いを制御した。 First, an optical disk was obtained by uniformly forming a recording layer made of an incomplete oxide of W on a sufficiently smoothed optical disk substrate by a sputtering method. At this time, sputtering was performed in a mixed atmosphere of argon and oxygen using a sputtering target consisting of a simple substance of W, and the oxygen gas concentration was changed to remove incomplete oxides of W. The degree of oxidation was controlled.
次に、 得られた光ディスクを、 波長 4 0 5 n mの G a Nレーザ ダイオー ドを光源に用いた光ディスク記録再生装置にセッ トし、 記録層に非可逆的変化を生じせしめる以上の照射パワーの記録 光を照射し、 ピッ トを形成した。 なお、 記録時には、 記録光の記 録パワー又はパルス幅を変えることにより、 異なる大きさのピッ トを形成した。  Next, the obtained optical disk was set in an optical disk recording / reproducing apparatus using a GaN laser diode having a wavelength of 405 nm as a light source, and the irradiation power was higher than that which caused an irreversible change in the recording layer. The recording light was irradiated to form a pit. During recording, pits of different sizes were formed by changing the recording power or pulse width of the recording light.
記録後の光ディ スクの表面を走査型電子顕微鏡 （Scanning Electron Microscope ： SEM) にて観察したところ、 第 1図に示す ように、 明瞭なピッ トパターンが形成されていることを確認した, また、 第 1 図から、 記録後のピッ トの幅及び長さは、 記録光源の パワー及びパルス幅によって変化することがわかった。 例えば、 記録パワーを低くすることにより、 短く且つ狭いピッ トの形成が 可能である。 具体的には、 第 1 図中、 最も左の列に形成されたピ ッ トは、 幅及び長さがいずれも 0. 2 5 mであり、 従来の光デ イスクのピッ ト幅に比べて微細なものとなる。  When the surface of the optical disc after recording was observed with a scanning electron microscope (SEM), it was confirmed that a clear pit pattern was formed as shown in Fig. 1. From Fig. 1, it was found that the width and length of the pit after recording varied with the power and pulse width of the recording light source. For example, a short and narrow pit can be formed by lowering the recording power. More specifically, the pit formed in the leftmost column in Fig. 1 has a width and length of 0.25 m, both of which are smaller than the pit width of a conventional optical disk. It becomes fine.
また、 得られた光ディスクに対して、 記録時と同じ波長の再生 光を照射したところ、 ピッ トに対応した再生信号が得られること を確認した。  When the obtained optical disc was irradiated with reproduction light having the same wavelength as during recording, it was confirmed that a reproduction signal corresponding to the pit could be obtained.
以上の結果より、 遷移金属の不完全酸化物からなる記録層と波 長 6 0 0 n m以下の光とを組み合わせることで記録再生が可能 であるとわかった。 また、 光記録媒体の記録材料として Wの不完 全酸化物を用いることで、 いわゆる D VD— R等の既存の追記型 光ディスクを上回る極めて微細なピッ 卜の形成が可能となり、 記 録密度のさらなる向上が可能であることがわかった。  From the above results, it was found that recording / reproducing was possible by combining a recording layer composed of an incomplete oxide of a transition metal with light having a wavelength of 600 nm or less. In addition, by using an incomplete oxide of W as a recording material of an optical recording medium, it is possible to form extremely fine pits exceeding those of existing write-once optical discs such as so-called DVD-R, and to increase the recording density. It has been found that further improvement is possible.
なお、 上述の Wを用いた場合と同様に、 M o、 C r、 F e、 及 び N bの不完全酸化物についてそれぞれ実際に光ディスクを作 製し、 記録及び再生を行ったところ、 いずれの材料においても波 長 6 0 0 n m以下の光と組み合わせる ことで記録再生可能であ ること、 及び従来の D V Dのピッ トよりさらに微細なピッ トが得 られることを確認した。 これらの中でも、 特に Wの不完全酸化物 及び M oの不完全酸化物を記録層に用いた光ディスクでは、 記録 光の照射による光学特性の変化が著しく、 良好な記録再生特性が 得られた。 As in the case of using W described above, Mo, Cr, Fe, and An optical disk was actually manufactured for each of the incomplete oxides of Nb and Nb, and recording and reproduction were performed.Either material could be recorded and reproduced by combining it with light having a wavelength of 600 nm or less. It was confirmed that finer pits could be obtained than conventional DVD pits. Among these, in particular, in the optical disk using the imperfect oxide of W and the imperfect oxide of Mo for the recording layer, the change in the optical characteristics due to the irradiation of the recording light was remarkable, and good recording / reproducing characteristics were obtained.
以上説明したように、 本発明によれば、 記録材料として遷移金 属の不完全酸化物を用いることにより、 波長 6 0 0 n m以下の光 で記録及び再生が可能であり、 且つ良好な記録再生特性を有する 光記録媒体を提供することができる。  As described above, according to the present invention, by using an incomplete oxide of a transition metal as a recording material, recording and reproduction can be performed with light having a wavelength of 600 nm or less, and good recording and reproduction can be performed. An optical recording medium having characteristics can be provided.
また、 本発明の光記録媒体を用いることで、 波長 6 0 0 n m以 下の短波長の光を記録再生に用いることが可能となり、 且つ良好 な記録再生特性が得られるので、 さ らなる高密度記録を実現する 新たな光記録方法を提供することが可能となる。  Further, by using the optical recording medium of the present invention, light having a short wavelength of 600 nm or less can be used for recording and reproduction, and good recording and reproduction characteristics can be obtained. It is possible to provide a new optical recording method for realizing density recording.

Claims

請求の範囲 The scope of the claims
1. 基板と、 当該基板上に形成された記録層とを有し、 1. having a substrate and a recording layer formed on the substrate,
上記記録層は、 遷移金属の不完全酸化物を記録材料として含有 し、  The recording layer contains an incomplete oxide of a transition metal as a recording material,
上記遷移金属の不完全酸化物における酸素の含有量が、 上記遷 移金属のと り う る価数に応じた化学量論組成の酸素含有量より 小さいことを特徴とする光記録媒体。  An optical recording medium, wherein the oxygen content of the incomplete oxide of the transition metal is smaller than the oxygen content of a stoichiometric composition corresponding to the valence of the transition metal.
2. 上記遷移金属の不完全酸化物は、 波長 6 0 0 n m以下の光 によって光学定数又は形状の変化を生じる ことを特徴とする請 求の範囲第 1項記載の光記録媒体。  2. The optical recording medium according to claim 1, wherein the incomplete oxide of the transition metal changes its optical constant or shape by light having a wavelength of 600 nm or less.
3. 上記遷移金属は、 T i 、 V、 C r、 M n、 F e、 N b、 C u、 N i 、 C o、 M o、 T a、 W、 Z r、 R u、 A gのうち少な く とも 1つであることを特徴とする請求の範囲第 1項記載の光 記録媒体。  3. The above transition metals are Ti, V, Cr, Mn, Fe, Nb, Cu, Ni, Co, Mo, Ta, W, Zr, Ru, Ag. 2. The optical recording medium according to claim 1, wherein at least one is provided.
4. 上記遷移金属の不完全酸化物が 3価の酸化物である場合、 当該遷移金属の不完全酸化物を組成割合 (ただし、 A は遷移金属である。） で表したとき、 0 < x < 0. 7 5であるこ とを特徴とする請求の範囲第 3項記載の光記録媒体。  4. When the incomplete oxide of the transition metal is a trivalent oxide, when the incomplete oxide of the transition metal is represented by a composition ratio (where A is a transition metal), 0 <x 4. The optical recording medium according to claim 3, wherein <0.75.
5. 上記遷移金属は M o又は Wであることを特徴とする請求の 範囲第 4項記載の光記録媒体。 5. The optical recording medium according to claim 4, wherein the transition metal is Mo or W.
6. 上記遷移金属の不完全酸化物にはさ らに他の元素が添加さ れていることを特徴とする請求の範囲第 1項記載の光記録媒体。 6. The optical recording medium according to claim 1, wherein another element is further added to the incomplete oxide of the transition metal.
7. 上記他の元素は、 遷移金属又は A 1 であることを特徴とす る請求の範囲第 6項記載の光記録媒体。 7. The optical recording medium according to claim 6, wherein the other element is a transition metal or A 1.
8 . 基板と遷移金属の不完全酸化物を記録材料として含有する 記録層とを備える光記録媒体に対して、 波長 6 0 0 n m以下の光 で記録再生を行う ことを特徴とする光記録方法。 8. Include substrate and incomplete oxide of transition metal as recording material An optical recording method comprising: performing recording and reproduction on an optical recording medium having a recording layer with light having a wavelength of 600 nm or less.
9. 上記遷移金属の不完全酸化物における酸素の含有量が、 上 記遷移金属のと り うる価数に応じた化学量論組成の酸素含有量 よ り小さいことを特徴とする請求の範囲第 8項記載の光記録方 法。  9. The oxygen content of the incomplete oxide of the transition metal is smaller than the oxygen content of the stoichiometric composition corresponding to the possible valence of the transition metal. Optical recording method described in clause 8.
1 0. 上記遷移金属は、 T i 、 V、 C r、 M n、 F e、 N b、 C u、 N i 、 C o、 M o、 T a、 W、 Z r、 R u、 A gのうち少 なく とも 1つであることを特徴とする請求の範囲第 8項記載の 光記録方法。  10. The transition metals are Ti, V, Cr, Mn, Fe, Nb, Cu, Ni, Co, Mo, Ta, W, Zr, Ru, Ag. 9. The optical recording method according to claim 8, wherein at least one of the optical recording methods is used.
1 1 . 上記遷移金属の不完全酸化物が 3価の酸化物である場合 当該遷移金属の不完全酸化物を組成割合 Aェ—x 0 x (ただし、 A は遷移金属である。） で表したとき、 0 < xく 0. 7 5であるこ とを特徴とする請求の範囲第 1 0項記載の光記録方法。 Table with x 0 x (however, A is a transition metal.) -. 1 1 above if incomplete oxide of a transition metal is trivalent oxides the transition metal of incomplete oxide of the composition ratio A E The optical recording method according to claim 10, wherein 0 <x and 0.75.
1 2. 上記遷移金属は M o又は Wであることを特徴とする請求 の範囲第 1 1項記載の光記録方法。 '  12. The optical recording method according to claim 11, wherein the transition metal is Mo or W. '
1 3. 上記遷移金属の不完全酸化物にはさ らに他の元素が添加 されていることを特徴とする請求の範囲第 8項記載の光記録方 法。  13. The optical recording method according to claim 8, wherein another element is further added to the incomplete oxide of the transition metal.
1 4. 上記他の元素は、 遷移金属又は A 1 であることを特徴と する請求の範囲第 1 3項記載の光記録方法。  14. The optical recording method according to claim 13, wherein the other element is a transition metal or A 1.
PCT/JP2003/001307 2002-02-22 2003-02-07 Optical recording medium and optical recording method WO2003070479A1 (en)

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US8124211B2 (en) 2007-03-28 2012-02-28 Ricoh Company, Ltd. Optical recording medium, sputtering target, and method for manufacturing the same
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