JPH08315416A - Optical information medium - Google Patents
Optical information mediumInfo
- Publication number
- JPH08315416A JPH08315416A JP7112983A JP11298395A JPH08315416A JP H08315416 A JPH08315416 A JP H08315416A JP 7112983 A JP7112983 A JP 7112983A JP 11298395 A JP11298395 A JP 11298395A JP H08315416 A JPH08315416 A JP H08315416A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- recording
- metal
- carbon
- recording medium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は光を照射することによっ
て情報に記録、消去および再生が可能であり、信号の記
録、消去を相変化によって行う光記録媒体に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium capable of recording, erasing and reproducing information by irradiating light, and recording and erasing signals by phase change.
【０００２】[0002]
【従来の技術】近年、光記録媒体は高度情報化社会にお
ける記録媒体の中心適役割りを担うものとして注目さ
れ、積極的に研究が進められている。光記録媒体のう
ち、特に光ディスクは今後マルチメディアの普及にとも
ない最も有力な記録媒体として注目されている。2. Description of the Related Art In recent years, optical recording media have been attracting attention as playing a central role in recording media in a highly information-oriented society, and research is being actively conducted. Among optical recording media, optical discs are attracting attention as the most promising recording media with the spread of multimedia.
【０００３】このような光ディスクには、コンパクトデ
ィスクやレーザディスクに代表される再生専用型、ユー
ザーによる情報の書き込みが可能な追記型、情報の書換
が可能な書換可能型の三種類がある。このうち書換可能
型には光磁気方式と相変化方式とがあり、相変化方式に
は結晶−非晶質間の相変化が生じる材料を記録層として
用いる。There are three types of such optical discs, a read-only type represented by a compact disc and a laser disc, a write-once type in which information can be written by a user, and a rewritable type in which information can be rewritten. Among them, the rewritable type includes a magneto-optical method and a phase change method. In the phase change method, a material that causes a phase change between crystal and amorphous is used as a recording layer.
【０００４】相変化方式においては、この記録層に、図
２に示すような記録信号に応じた強度変調をかけたレー
ザ光を照射することで簡単にオーバーライトが可能であ
る。すなわち、強いパワーのレーザ光を短時間照射した
位置は、融点以上に急熱され融解させた後に、急冷され
ることにより非晶質状態（記録ピット）が形成され、こ
れより弱いパワーのレーザー光が照射された位置は融点
よりも低い結晶化可能温度範囲まで昇温され結晶状態が
形成される。In the phase change system, overwriting can be easily performed by irradiating the recording layer with laser light whose intensity is modulated according to a recording signal as shown in FIG. That is, at a position irradiated with a laser beam having a strong power for a short time, an amorphous state (recording pit) is formed by being rapidly heated to a temperature equal to or higher than the melting point and melted, and then rapidly cooled. The position irradiated with is heated to a crystallizable temperature range lower than the melting point and a crystalline state is formed.
【０００５】従来より相変化型光ディスクは信号振幅を
大きくしたり、繰り返し特性を改善したりするため、図
３に示すような基板上に４層の多層膜を有する積層構造
が多用されている。すなわち、ポリカーボネート樹脂な
どの透明基板１１上に、透明な誘電体層１２、記録層１
３、透明な誘電体層１４、反射層１５を設け誘電体層１
４を干渉層とした４層構造である。Conventionally, in order to increase the signal amplitude and improve the repetitive characteristics, the phase change type optical disk has often used a laminated structure having a multilayer film of four layers on a substrate as shown in FIG. That is, a transparent dielectric layer 12 and a recording layer 1 are formed on a transparent substrate 11 such as a polycarbonate resin.
3, the transparent dielectric layer 14 and the reflective layer 15 are provided, and the dielectric layer 1 is provided.
4 is a four-layer structure in which 4 is an interference layer.
【０００６】各層に用いられる材料として、誘電体層と
しては記録層の保護特性に優れ、かつ記録消去の繰り返
しに十分な機械特性を有していることから、カルコゲン
化合物と酸化物あるいは窒化物などの混合物が一般的に
広く用いられている。また記録層としては結晶化速度の
速いものが好ましく、Ｓｂ−Ｓｅ合金、Ｓｂ 2 Ｔｅ3 合
金、Ｔｅ−Ｇｅ−Ｓｂ合金が良く知られている。A dielectric layer is used as a material used for each layer.
Has excellent recording layer protection characteristics, and recording and erasing can be repeated.
Since it has sufficient mechanical properties for
Mixtures of compounds and oxides or nitrides are generally
Widely used. Also, the crystallization rate of the recording layer
Fast one is preferable, Sb-Se alloy, Sb 2Te3Combined
Gold and Te-Ge-Sb alloys are well known.
【０００７】反射層としてはＡｌを主成分とする合金が
安価なうえ耐環境性にも優れており、広く用いられてい
る。As the reflective layer, an alloy containing Al as a main component is widely used because it is inexpensive and has excellent environmental resistance.
【０００８】[0008]
【発明が解決しようとする課題】従来の４層構造の相変
化型光記録媒体においては、オーバーライトを行った
際、記録層でのレーザ光の吸収は、一般に非晶質状態の
方が結晶状態よりも大きいため、記録ピットを形成する
際、記録前の状態が結晶状態か非晶質状態かにより形成
される記録ピットの形状や大きさにばらつきが生じ、こ
のばらつきがジッターの増加、ウインドウマージンの減
少および消去比の低下が発生するという問題があった。In a conventional phase change type optical recording medium having a four-layer structure, upon overwriting, the absorption of laser light in the recording layer is generally more crystalline in the amorphous state. Since the size of the recording pit is larger than that of the recording pit, the shape and size of the recording pit formed when the recording pit is formed depends on whether the state before recording is a crystalline state or an amorphous state. There is a problem that the margin is reduced and the erase ratio is reduced.
【０００９】特にピットエッジ記録においては、データ
をピットの両端に乗せるため、記録ピットの形状や大き
さのばらつきが直接エラーとなってしまい、相変化型光
ディスクの記録密度向上を阻害する要因となっていた。
本発明は、このような課題を解決するためのものであ
り、記録前の記録層の状態に依らず均一な大きさ、形状
のピットを形成することを課題とする。Particularly in pit edge recording, since data is placed on both ends of the pit, variations in the shape and size of the recording pits directly cause an error, which becomes a factor that hinders the improvement of the recording density of the phase change optical disk. Was there.
The present invention is intended to solve such a problem, and an object thereof is to form pits having a uniform size and shape regardless of the state of the recording layer before recording.
【００１０】[0010]
【課題を解決するための手段】本発明者らは、消去比が
高く、またオーバーライト前の記録層の状態によらず、
オーバーライトにより形状や大きさにばらつきのない記
録ピットを形成できる相変化型光記録媒体を開発すべく
鋭意研究を重ねた結果、記録層と反射層の間の保護層と
して、カーボンに金属を添加した層を用いることにより
その課題を達成しうることを見い出し、この知見に基づ
いて本発明を完成するに至った。The present inventors have found that the erasing ratio is high and the erasing ratio does not depend on the state of the recording layer before overwriting.
As a result of intensive research to develop a phase-change optical recording medium that can form recording pits with uniform shape and size by overwriting, a metal was added to carbon as a protective layer between the recording layer and the reflective layer. It was found that the problem can be achieved by using such a layer, and the present invention has been completed based on this finding.
【００１１】すなわち本発明は、光を照射することによ
って情報の記録、消去および再生が可能な相変化型光記
録媒体において、透明基板上に、誘電体層、記録層、カ
ーボンに金属を添加した層、反射層を順次積層した構造
であることを特徴とする光記録媒体である。一般に結晶
状態の記録層は非晶質状態に比較して、熱伝導率が大き
く、溶融するためには潜熱分の熱量が必要であり、非晶
質状態よりも記録ピットを形成するためには大きな熱量
を必要とする。That is, according to the present invention, in a phase change type optical recording medium capable of recording, erasing and reproducing information by irradiating light, a metal is added to a dielectric layer, a recording layer and carbon on a transparent substrate. An optical recording medium having a structure in which a layer and a reflective layer are sequentially laminated. In general, a recording layer in a crystalline state has a higher thermal conductivity than that in an amorphous state, and a heat amount corresponding to the latent heat is required for melting, and it is necessary to form a recording pit more than an amorphous state. Requires a large amount of heat.
【００１２】従って、記録前の記録層が結晶状態である
か非晶質状態であるかに関わらず同じ大きさの記録ピッ
トを形成するためには、結晶状態の吸収量は非晶質状態
の吸収量よりも大きいことが望ましい。しかし、従来の
相変化型光記録媒体では、信号振幅を大きくしたり、繰
り返し特性を向上させる観点から、記録層の上に設けら
れた誘電体層または反射層により多重干渉が起こり、非
晶質状態の吸収率の方が結晶状態の値よりも大きくなっ
ていた。従って、図５に示すように記録前に非晶質状態
であった領域の上に記録されたピットは、結晶状態であ
った領域の上に記録されたピットと形状が異なってしま
う。Therefore, in order to form recording pits of the same size regardless of whether the recording layer before recording is in the crystalline state or the amorphous state, the absorption amount of the crystalline state is in the amorphous state. It is desirable that it is larger than the absorption amount. However, in the conventional phase change type optical recording medium, from the viewpoint of increasing the signal amplitude and improving the repeating characteristics, multiple interference occurs due to the dielectric layer or the reflective layer provided on the recording layer, and The absorptance of the state was larger than that of the crystalline state. Therefore, as shown in FIG. 5, the pits recorded on the region which was in the amorphous state before recording have a different shape from the pits recorded on the region which was in the crystalline state.
【００１３】一方、本発明の相変化型光記録媒体によれ
ば、記録層と反射層の間の保護層としてカーボンに金属
を添加した層を用いることで、非晶質状態の記録層への
レーザ光の吸収を低減し、結晶状態の記録層のレーザ光
の吸収以下とすることができる。従って、図４に示すよ
うに記録前の記録層の状態によらず、記録ピットの形状
や大きさのばらつきを低減できる。On the other hand, according to the phase change type optical recording medium of the present invention, by using a layer in which a metal is added to carbon as a protective layer between the recording layer and the reflective layer, the recording layer in an amorphous state is formed. It is possible to reduce the absorption of the laser light to be equal to or less than the absorption of the laser light of the recording layer in the crystalline state. Therefore, as shown in FIG. 4, it is possible to reduce the variation in the shape and size of the recording pit regardless of the state of the recording layer before recording.
【００１４】本発明の相変化型光記録媒体の層構造は、
図１に示すように、透明基板１上に、誘電体層２、記録
層３、カーボンに金属を添加した層（以下、金属添加カ
ーボン層という）４、反射層５を順次積層した構造であ
る。本発明において金属添加カーボン層の膜厚は２ｎｍ
以上４０ｎｍ以下が好ましい。金属添加カーボン層の膜
厚が２ｎｍより薄いと金属添加カーボン層での吸収が不
十分で、非晶質状態の記録層での吸収が大きくなり、結
晶状態の記録層の吸収を、非晶質状態の記録層での吸収
以上にすることができない。The layer structure of the phase change type optical recording medium of the present invention is as follows:
As shown in FIG. 1, it has a structure in which a dielectric layer 2, a recording layer 3, a layer in which a metal is added to carbon (hereinafter referred to as a metal-added carbon layer) 4, and a reflective layer 5 are sequentially laminated on a transparent substrate 1. . In the present invention, the thickness of the metal-added carbon layer is 2 nm
It is preferably 40 nm or more and 40 nm or less. When the film thickness of the metal-added carbon layer is less than 2 nm, the absorption in the metal-added carbon layer is insufficient, the absorption in the amorphous recording layer becomes large, and the absorption in the crystalline recording layer becomes amorphous. The state cannot be more than absorbed by the recording layer.
【００１５】金属添加カーボン層の膜厚が４０ｎｍより
厚いと光学的なコントラストが小さくなり、信号強度の
低下などが発生する。金属添加カーボン層の膜厚はこの
ように最適範囲が存在し、２ｎｍ以上４０ｎｍ以下の範
囲が適当であるが、更に５ｎｍ以上３０ｎｍ以下の範囲
がより望ましい。カーボンに添加する金属としては消衰
係数が大きく、かつ融点の高いことが要求され、Ａｌ、
Ａｇ、Ｗ、Ｔｉ、Ｍｏ、Ｎｉ、Ｐｔ、Ｃｒ、Ｐｄ、Ｖ、
Ｔｃ、Ｎｂ、Ｔａ、Ｒｅ、Ｉｒの内から選ばれる少なく
とも１種類が好ましい。When the film thickness of the metal-added carbon layer is thicker than 40 nm, the optical contrast becomes small and the signal strength is lowered. The film thickness of the metal-added carbon layer has an optimum range as described above, and the range of 2 nm or more and 40 nm or less is suitable, and the range of 5 nm or more and 30 nm or less is more preferable. The metal added to carbon is required to have a large extinction coefficient and a high melting point.
Ag, W, Ti, Mo, Ni, Pt, Cr, Pd, V,
At least one selected from Tc, Nb, Ta, Re and Ir is preferable.
【００１６】金属添加カーボン層の成膜方法としては、
カーボンと金属の別々のターゲットを同時にスパッタリ
ングする共スパッタや、カーボンに金属を添加したター
ゲットをスパッタリングする方法などが挙げられる。特
に共スパッタはカーボンと金属の混合比を任意に変えら
れ、最適な消衰係数を得ることができるので有効であ
る。As a method for forming the metal-added carbon layer,
Examples thereof include co-sputtering in which separate targets of carbon and metal are simultaneously sputtered, and a method in which a target in which a metal is added to carbon is sputtered. Particularly, co-sputtering is effective because the mixing ratio of carbon and metal can be arbitrarily changed and an optimum extinction coefficient can be obtained.
【００１７】金属添加カーボン層の消衰係数は０．０５
以上２．５以下が好ましい。消衰係数が０．０５より小
さいときは金属添加カーボン層においてレーザ光の吸収
がほとんどなされず、多重干渉による非晶質状態の記録
層への吸収が発生してしまう。一方、消衰係数が２．５
より大きいときは記録層と金属添加カーボン層との界面
での反射が大きくなり、非晶質状態の記録層でのレーザ
光の吸収が減少しないため、非晶質状態の記録層の吸収
を結晶状体の記録層の吸収以下とすることができない。
金属添加カーボン層の消衰係数はこのように最適範囲が
存在し、０．０５以上２．５以下の範囲が適当である
が、更に０．１以上２．０以下の範囲がより望ましい。The extinction coefficient of the metal-added carbon layer is 0.05.
It is preferably not less than 2.5 and not more than 2.5. When the extinction coefficient is smaller than 0.05, the laser beam is hardly absorbed in the metal-added carbon layer, and absorption in the amorphous recording layer occurs due to multiple interference. On the other hand, the extinction coefficient is 2.5
When it is larger, the reflection at the interface between the recording layer and the metal-added carbon layer becomes large, and the absorption of laser light in the amorphous recording layer does not decrease. It cannot be less than or equal to the absorption of the crystalline recording layer.
The extinction coefficient of the metal-added carbon layer has an optimum range as described above, and a range of 0.05 or more and 2.5 or less is suitable, but a range of 0.1 or more and 2.0 or less is more preferable.
【００１８】本発明の相変化型光記録媒体における基板
と記録層の間に設けられる誘電体層の膜厚は、１００ｎ
ｍ以上４００ｎｍ以下が好ましい。誘電体層の膜厚が１
００ｎｍより薄いと繰り返し記録を行ったときに基板へ
の熱的ダメージが大きく信号品質が低下する。誘電体層
の膜厚が４００ｎｍより厚いと成膜に時間がかかり、成
膜時に発生する熱の影響により基板変形が発生する恐れ
がある。また、本発明の効果は非晶質状態の記録層を通
過する光量が多いほど大きくなる。従って、反射率が最
小となる誘電体層膜厚において最大の効果を発揮し、そ
の近傍の膜厚であることが望ましい。従って、誘電体層
の膜厚は２００ｎｍ以上３００ｎｍ以下の範囲がさらに
望ましい。The film thickness of the dielectric layer provided between the substrate and the recording layer in the phase change optical recording medium of the present invention is 100 n.
It is preferably m or more and 400 nm or less. The thickness of the dielectric layer is 1
If the thickness is less than 00 nm, the thermal damage to the substrate is large when the recording is repeated, and the signal quality deteriorates. If the film thickness of the dielectric layer is thicker than 400 nm, it takes a long time to form the film, and the substrate may be deformed due to the influence of heat generated during the film formation. Further, the effect of the present invention becomes greater as the amount of light passing through the amorphous recording layer increases. Therefore, it is desirable that the maximum effect is exhibited in the thickness of the dielectric layer where the reflectance is minimum, and the thickness is in the vicinity thereof. Therefore, the film thickness of the dielectric layer is more preferably 200 nm or more and 300 nm or less.
【００１９】記録層の膜厚は１０ｎｍ以上５０ｎｍ以下
が望ましい。記録層の膜厚が１０ｎｍより薄いと結晶状
態と非晶質状態との反射率差が小さくなり、信号品質が
低下する。また、記録層膜厚が５０ｎｍより厚いと非晶
質状態の記録層での吸収が大きくなり、結晶状態の記録
層の吸収を、非晶質状態の記録層での吸収以上にするこ
とができない。記録層の膜厚はこのように最適範囲が存
在し１０ｎｍ以上５０ｎｍ以下の範囲が適当であるが、
更に２０ｎｍ以上３５ｎｍ以下の範囲がより望ましい。The thickness of the recording layer is preferably 10 nm or more and 50 nm or less. When the film thickness of the recording layer is less than 10 nm, the difference in reflectance between the crystalline state and the amorphous state becomes small and the signal quality deteriorates. Further, if the recording layer thickness is thicker than 50 nm, the absorption in the amorphous recording layer becomes large, and the absorption in the crystalline recording layer cannot exceed the absorption in the amorphous recording layer. . The film thickness of the recording layer has an optimum range as described above, and a range of 10 nm or more and 50 nm or less is suitable.
Furthermore, the range of 20 nm or more and 35 nm or less is more desirable.
【００２０】記録層の材料としては公知の相変化材料が
使用可能であり、例えばＧｅＴｅ系、ＧｅＴｅＳｂ系、
ＩｎＳｂ系またはこれらの系の少量の元素を添加した系
などが上げられる。本発明の相変化型光記録媒体に用い
られる基板材料としては、ガラス、ポリプロピレン、ア
クリル樹脂、ポリカーボネート樹脂、スチレン樹脂、塩
化ビニル樹脂エポキシ樹脂、ポリオレフィン樹脂などの
透明材料が挙げられるが、これらの中でポリカーボネー
ト樹脂およびアクリル樹脂が光学的特性面で好適であ
る。As the material of the recording layer, a known phase change material can be used, for example, GeTe type, GeTeSb type,
Examples include InSb-based systems and systems in which small amounts of these systems are added. Examples of the substrate material used in the phase change type optical recording medium of the present invention include transparent materials such as glass, polypropylene, acrylic resin, polycarbonate resin, styrene resin, vinyl chloride resin epoxy resin, and polyolefin resin. Therefore, polycarbonate resin and acrylic resin are preferable in terms of optical characteristics.
【００２１】本発明の相変化型光記録媒体の誘電体層の
材料としては、公知の誘電体材料が使用可能であり、Ｚ
ｎＳ，ＳｉＯ2，ＳｉＮ，ＡｌＮ，Ａｌ2 Ｏ3 、Ｔａ2
Ｏ5等の金属硫化物、金属酸化物、金属窒化物、金属炭
化物、金属セレン化物、またはこれらの混合物などが挙
げられる。本発明の相変化型光記録媒体の反射層の材料
としては、公知の材料が使用でき、Ａｌ、Ａｕ、Ｎｉ、
Ｃｒ等やこれらの合金、またはこれらの金属や合金に小
量の元素を添加したものなどが挙げられる。As the material of the dielectric layer of the phase change type optical recording medium of the present invention, known dielectric materials can be used.
nS, SiO 2 , SiN, AlN, Al 2 O 3 , Ta 2
Examples thereof include metal sulfides such as O 5 , metal oxides, metal nitrides, metal carbides, metal selenides, and mixtures thereof. As the material of the reflective layer of the phase change type optical recording medium of the present invention, known materials can be used, and Al, Au, Ni,
Examples thereof include Cr and the like, alloys of these, and those obtained by adding a small amount of element to these metals and alloys.
【００２２】本発明の相変化型光記録媒体における記録
膜の形成方法については、特に制限はなく、公知の蒸着
法やスパッタリング法などを用いることが出来る。The method of forming the recording film in the phase change type optical recording medium of the present invention is not particularly limited, and a known vapor deposition method, sputtering method or the like can be used.
【００２３】[0023]
【実施例】次に、実施例により本発明を更に詳細に説明
する。Next, the present invention will be described in more detail by way of examples.
【００２４】[0024]
【実施例１】案内溝を設けた清浄なポリカーボネート基
板上に、厚さ２００ｎｍのＺｎＳ−ＳｉＯ2 薄膜からな
る保護層、厚さ２５ｎｍのＳｂＴｅＧｅ合金薄膜からな
る記録層、厚さ２０ｎｍのカーボンにＷを３０ｖｏｌ％
添加した層、厚さ１５０ｎｍのＡｌ合金薄膜からなる反
射層を順次積層した相変化型光ディスクをスパッタリン
グ法により成膜し、ついで記録膜表面を紫外線硬化樹脂
で被覆した。カーボンにＷを添加した層はカーボンとＷ
の別々のターゲットを共スパッタし、Ｗが３０ｖｏｌ％
になるよう各々のスパッタパワーを調整して成膜した。EXAMPLE 1 A protective layer made of a ZnS-SiO 2 thin film having a thickness of 200 nm, a recording layer made of a SbTeGe alloy thin film having a thickness of 25 nm, and a carbon layer having a thickness of 20 nm with W are formed on a clean polycarbonate substrate having guide grooves. 30 vol%
A phase-change optical disk in which the added layer and a reflective layer made of an Al alloy thin film having a thickness of 150 nm were sequentially laminated was formed into a film by a sputtering method, and then the surface of the recording film was covered with an ultraviolet curable resin. The layer in which W is added to carbon is carbon and W
Co-sputtering different targets of W, 30vol% W
The film was formed by adjusting the respective sputter powers so that
【００２５】こうして作成した片面ディスク２枚を記録
面が内側になるようにホットメルト接着剤で接着し全面
密着構造の光ディスクとした。こうして作成した光ディ
スクを線速度１５ｍ／ｓｅｃで回転させ、パルス幅２０
ｎｓｅｃ、周波数１６ＭＨｚと６ＭＨｚを図２に示すよ
うな記録波形で交互にオーバーライトし、それぞれの周
波数の消去比を測定した。この時の光学系は、波長λ＝
６８０ｎｍ、対物レンズのＮＡはＮＡ＝０．６、バイア
スパワーは５ｍＷ、ピークパワーは１３ｍＷである。The two single-sided discs thus prepared were adhered to each other with a hot melt adhesive so that the recording surface was on the inside, to obtain an optical disc having a full-surface contact structure. The optical disc thus created was rotated at a linear velocity of 15 m / sec and a pulse width of 20
nsec, frequencies 16 MHz and 6 MHz were alternately overwritten with a recording waveform as shown in FIG. 2, and the erasing ratio of each frequency was measured. At this time, the optical system has a wavelength λ =
680 nm, NA of the objective lens is NA = 0.6, bias power is 5 mW, and peak power is 13 mW.
【００２６】その結果、６ＭＨｚの信号が記録してあっ
た上に１６ＭＨｚの信号をオーバーライトしたとき、１
６ＭＨｚのＣ／Ｎ比は５０ｄＢ以上が得られ、６ＭＨｚ
の信号の消去比は３２ｄＢであり、後述する比較例１の
光ディスクに比較して１２ｄＢの消去比改善がはかれ
た。この時の波形を観察すると図６に示すような波形で
あり、振幅変調は全く見られなかった。As a result, when the signal of 6 MHz is recorded and the signal of 16 MHz is overwritten, 1
The C / N ratio of 6 MHz is 50 dB or more, and 6 MHz
The erasing ratio of the signal is 32 dB, and the erasing ratio is improved by 12 dB as compared with the optical disc of Comparative Example 1 described later. When the waveform at this time was observed, the waveform was as shown in FIG. 6, and no amplitude modulation was observed.
【００２７】また１０万回の繰り返し記録を行ったとこ
ろ、ジッターは初期と変わらず、ビットエラーレートも
悪化しなかった。When recording was repeated 100,000 times, the jitter was the same as at the beginning and the bit error rate did not deteriorate.
【００２８】[0028]
【実施例２】案内溝を設けた清浄なポリカーボネート基
板上に、厚さ２００ｎｍのＺｎＳ−ＳｉＯ2 薄膜からな
る保護層、厚さ２５ｎｍのＳｂＴｅＧｅ合金薄膜からな
る記録層、厚さ２０ｎｍのカーボンにＭｏを３０ｖｏｌ
％添加した層、厚さ１５０ｎｍのＡｌ合金薄膜からなる
反射層を順次積層した相変化型光ディスクをスパッタリ
ング法により成膜し、ついで記録膜表面を紫外線硬化樹
脂で被覆した。カーボンにＭｏを添加した層はカーボン
とＭｏの別々のターゲットを共スパッタし、Ｍｏが３０
ｖｏｌ％になるよう各々のスパッタパワーを調整して成
膜した。Example 2 A protective layer made of a ZnS—SiO 2 thin film having a thickness of 200 nm, a recording layer made of a SbTeGe alloy thin film having a thickness of 25 nm, and a carbon layer having a thickness of 20 nm containing Mo on a clean polycarbonate substrate having guide grooves. 30 vol
% Addition layer and a reflection layer consisting of an Al alloy thin film having a thickness of 150 nm were sequentially laminated to form a film by a sputtering method, and then the surface of the recording film was covered with an ultraviolet curable resin. The layer in which Mo is added to carbon co-sputters different targets of carbon and Mo,
The film was formed by adjusting the sputtering power of each so as to be vol%.
【００２９】こうして作成した片面ディスク２枚を記録
面が内側になるようにホットメルト接着剤で接着し全面
密着構造の光ディスクとした。こうして作成した光ディ
スクを線速度１５ｍ／ｓｅｃで回転させ、パルス幅２０
ｎｓｅｃ、周波数１６ＭＨｚと６ＭＨｚを図２に示すよ
うな記録波形で交互にオーバーライトし、それぞれの周
波数の消去比を測定した。この時の光学系は、波長λ＝
６８０ｎｍ、対物レンズのＮＡはＮＡ＝０．６、バイア
スパワーは５ｍＷ、ピークパワーは１３ｍＷである。The two single-sided discs thus prepared were adhered with a hot-melt adhesive so that the recording surface was on the inside, to obtain an optical disc having a full-face contact structure. The optical disc thus created was rotated at a linear velocity of 15 m / sec and a pulse width of 20
nsec, frequencies 16 MHz and 6 MHz were alternately overwritten with a recording waveform as shown in FIG. 2, and the erasing ratio of each frequency was measured. At this time, the optical system has a wavelength λ =
680 nm, NA of the objective lens is NA = 0.6, bias power is 5 mW, and peak power is 13 mW.
【００３０】その結果、６ＭＨｚの信号が記録してあっ
た上に１６ＭＨｚの信号をオーバーライトしたとき、１
６ＭＨｚのＣ／Ｎ比は５０ｄＢ以上が得られ、６ＭＨｚ
の信号の消去比は３１ｄＢであり、後述する比較例１の
光ディスクに比較して１１ｄＢの消去比改善がはかれ
た。この時の波形を観察すると図６に示すような波形で
あり、振幅変調は全く見られなかった。As a result, when the signal of 6 MHz was recorded and the signal of 16 MHz was overwritten, 1
The C / N ratio of 6 MHz is 50 dB or more, and 6 MHz
The erasing ratio of the signal is 31 dB, and the erasing ratio is improved by 11 dB as compared with the optical disc of Comparative Example 1 described later. When the waveform at this time was observed, the waveform was as shown in FIG. 6, and no amplitude modulation was observed.
【００３１】また１０万回の繰り返し記録を行ったとこ
ろ、ジッターは初期と変わらず、ビットエラーレートも
悪化しなかった。When recording was repeated 100,000 times, the jitter was the same as at the beginning and the bit error rate did not deteriorate.
【００３２】[0032]
【比較例１】案内溝を設けた清浄なポリカーボネート基
板上に、厚さ２００ｎｍのＺｎＳ−ＳｉＯ2 薄膜からな
る保護層、厚さ２５ｎｍのＳｂＴｅＧｅ合金薄膜からな
る記録層、厚さ２０ｎｍのＺｎＳ−ＳｉＯ2 薄膜からな
る干渉層、厚さ１５０ｎｍのＡｌ合金薄膜からなる反射
層を順次積層した相変化型光ディスクをスパッタリング
法により成膜し、ついで記録膜表面を紫外線硬化樹脂で
被覆した。こうして作製した片面ディスク２枚を記録面
が内側になるようにホットメルト接着剤で接着し全面密
着構造の光ディスクとした。Comparative Example 1 A protective layer made of a ZnS—SiO 2 thin film having a thickness of 200 nm, a recording layer made of a SbTeGe alloy thin film having a thickness of 25 nm, and a ZnS—SiO having a thickness of 20 nm were formed on a clean polycarbonate substrate having guide grooves. A phase-change optical disk in which an interference layer composed of two thin films and a reflection layer composed of an Al alloy thin film having a thickness of 150 nm were sequentially laminated was formed by a sputtering method, and then the surface of the recording film was covered with an ultraviolet curable resin. The two single-sided discs thus produced were adhered with a hot melt adhesive so that the recording surface was on the inside, to obtain an optical disc having a full-face contact structure.
【００３３】その結果、６ＭＨｚの信号が記録してあっ
た上に１６ＭＨｚの信号をオーバーライトしたときの６
ＭＨｚの信号の消去比は２０ｄＢであった。この時の波
形を観察したところ、図７に示すような６ＭＨｚの周波
数の振幅変調が見られ、明らかにオーバーライト前の記
録層の状態（結晶状態の未記録部と非晶質状態の記録ピ
ット）により形成されるピットの大きさ、形状が変化し
ていることが分かる。As a result, when the signal of 6 MHz is recorded and the signal of 16 MHz is overwritten, 6
The cancellation ratio of the MHz signal was 20 dB. When the waveform at this time was observed, amplitude modulation at a frequency of 6 MHz as shown in FIG. 7 was observed, and clearly the state of the recording layer before overwriting (the unrecorded portion in the crystalline state and the recording pits in the amorphous state) was observed. It can be seen that the size and shape of the pit formed by) have changed.
【００３４】また１０万回の繰り返し記録を行ったとこ
ろ、ジッターが大きくなり、ビットエラーレートは大幅
に悪化した。When recording was repeated 100,000 times, the jitter increased and the bit error rate significantly deteriorated.
【００３５】[0035]
【発明の効果】本発明によれば、書換可能な相変化型光
記録媒体において、透明基板上に、誘電体層、記録層、
金属添加カーボン層、反射層を順次積層した構造とする
ことで、記録前の記録層の状態が結晶状態であるか非晶
質状態であるかによらず、記録ピットの形状や大きさの
ばらつきを低減させることができる。According to the present invention, in a rewritable phase change type optical recording medium, a dielectric layer, a recording layer,
By adopting a structure in which a metal-added carbon layer and a reflective layer are sequentially laminated, the shape and size of recording pits will vary regardless of whether the state of the recording layer before recording is crystalline or amorphous. Can be reduced.
【００３６】これによりジッター減少、消去比向上、ウ
インドウマージン増加が図れ、エラーを低減した光記録
媒体を提供することができる。As a result, it is possible to provide an optical recording medium in which the jitter is reduced, the erase ratio is improved, the window margin is increased, and the error is reduced.
【図１】本発明の光記録媒体の構造を示す断面図であ
る。FIG. 1 is a sectional view showing the structure of an optical recording medium of the present invention.
【図２】オーバーライト時のレーザービーム強度の波形
図である。FIG. 2 is a waveform diagram of laser beam intensity during overwriting.
【図３】従来の４層構造の光記録媒体の構造を示す断面
図である。FIG. 3 is a cross-sectional view showing the structure of a conventional four-layer optical recording medium.
【図４】本発明の光記録媒体において、非晶質状態と結
晶状態の上に記録した場合に形成されるピット形状の概
念図である。FIG. 4 is a conceptual diagram of a pit shape formed when recording is performed on an amorphous state and a crystalline state in the optical recording medium of the present invention.
【図５】従来の光記録媒体において、非晶質状態と結晶
状態の上に記録した場合に形成されるピット形状の概念
図である。FIG. 5 is a conceptual diagram of a pit shape formed when recording is performed on an amorphous state and a crystalline state in a conventional optical recording medium.
【図６】本発明の光記録媒体における、オーバーライト
後の信号波形である。FIG. 6 is a signal waveform after overwriting in the optical recording medium of the present invention.
【図７】従来の光記録媒体における、オーバーライト後
の信号波形である。FIG. 7 is a signal waveform after overwriting in the conventional optical recording medium.
１ 透明基板 ２ 誘電体層 ３ 記録層 ４ 金属添加カーボン層 ５ 反射層 １１ 透明基板 １２ 第１の誘電体層 １３ 記録層 １４ 第２の誘電体層 １５ 反射層 1 Transparent Substrate 2 Dielectric Layer 3 Recording Layer 4 Metal-Added Carbon Layer 5 Reflective Layer 11 Transparent Substrate 12 First Dielectric Layer 13 Recording Layer 14 Second Dielectric Layer 15 Reflective Layer
Claims (5)
消去および再生が可能な相変化型光記録媒体において、
透明基板上に、誘電体層、記録層、カーボンに金属を添
加した層、反射層を順次積層した構造であることを特徴
とする光記録媒体。1. Recording of information by irradiating with light,
In a phase change type optical recording medium that can be erased and reproduced,
An optical recording medium having a structure in which a dielectric layer, a recording layer, a layer in which a metal is added to carbon, and a reflective layer are sequentially laminated on a transparent substrate.
ｏ、Ｎｉ、Ｐｔ、Ｃｒ、Ｐｄ、Ｖ、Ｔｃ、Ｎｂ、Ｔａ、
Ｒｅ、Ｉｒのうちから選ばれる少なくとも１種類の金属
を添加したものからなることを特徴とする請求項１に記
載の光記録媒体。2. Al, Ag, W, Ti, M in carbon
o, Ni, Pt, Cr, Pd, V, Tc, Nb, Ta,
The optical recording medium according to claim 1, wherein the optical recording medium comprises at least one metal selected from Re and Ir.
が０．０５以上２．５以下であることを特徴とする請求
項２に記載の光記録媒体。3. The optical recording medium according to claim 2, wherein the extinction coefficient of the layer in which a metal is added to carbon is 0.05 or more and 2.5 or less.
ｎｍ以上４０ｎｍ以下であることを特徴とする請求項３
に記載の光記録媒体。4. The thickness of a layer in which a metal is added to carbon is 2
4. The thickness is not less than 40 nm and not more than 40 nm.
The optical recording medium according to 1.
体層の膜厚が１００ｎｍ以上４００ｎｍ以下であり、記
録層の膜厚が１０ｎｍ以上５０ｎｍ以下であることを特
徴とする請求項４に記載の光記録媒体。5. The film thickness of the dielectric layer provided between the transparent substrate and the recording layer is 100 nm or more and 400 nm or less, and the film thickness of the recording layer is 10 nm or more and 50 nm or less. The optical recording medium described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7112983A JPH08315416A (en) | 1995-05-11 | 1995-05-11 | Optical information medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7112983A JPH08315416A (en) | 1995-05-11 | 1995-05-11 | Optical information medium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH08315416A true JPH08315416A (en) | 1996-11-29 |
Family
ID=14600474
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP7112983A Withdrawn JPH08315416A (en) | 1995-05-11 | 1995-05-11 | Optical information medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH08315416A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111095108A (en) * | 2017-07-17 | 2020-05-01 | Asml荷兰有限公司 | Information determination apparatus and method |
-
1995
- 1995-05-11 JP JP7112983A patent/JPH08315416A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111095108A (en) * | 2017-07-17 | 2020-05-01 | Asml荷兰有限公司 | Information determination apparatus and method |
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