JP4070491B2 - Optical recording medium and manufacturing method thereof - Google Patents

Description

【００３０】
上記表１には、（１）第３保護層の元素のモル濃度（％）、（２）第３保護層材料における化学結合種（元素と元素の結合の種類）別の結合数順位と、各化学結合種の結合エネルギー（ｋｃａｌ／モル）、（３）第３保護層の構造、（４）第３保護層の平均電気陰性度、（５）その第３保護層を用いたＤＶＤ＋ＲＷ媒体のヒートサイクル試験後の欠陥率を示した。なお、第３保護層の構造が結晶であるかアモルファスであるかは、電子線回折でハローパターンが見られればアモルファスであると判定した。また、「欠陥率」とは、未記録状態の媒体の記録可能領域にレーザービームを照射しながら案内溝を走査した際、走査した溝の長さに対する、反射率が予め決められた反射率の規格値から外れた部分の長さの比を言う。更に、欠陥率の欄に、例えば「７．７Ｅ−０５」とあるのは「７．７×１０^−５」のことである。
【００３１】
各種Ｓｉを含有する第３保護層を用いたＤＶＤ＋ＲＷ媒体のヒートサイクル試験後の欠陥率と、第３保護層材料のＳｉ含有量及び平均電気陰性度の関係を図３、図４に示した。図３、図４から、信頼性を確保できる欠陥率である１．０Ｅ−０５（＝１．０×１０^−５）を確保するためには、第３保護層材料のＳｉのモル濃度が３５％以上、平均電気陰性度２．３以下とすると良いことが分る。
なお、ここでいう平均電気陰性度とは、構成元素の電気陰性度を各元素の存在する割合に応じて平均化したものであり、第３保護層の平均電気陰性度をＥｎ（ａｖｅ）とし、構成元素のモル濃度（％）をｍｉ、構成元素の電気陰性度をＥｎｉとしたときに、次の式で定義される。
Ｅｎ（ａｖｅ）＝Σｍｉ・Ｅｎｉ
この平均電気陰性度の下限は、本発明の効果を奏するか否かの点からは特にないが、実際上は、表１の実験１５、１８で見られる金属単体のＴｉ、Ｔａの場合の１．５位が限界値と考えられる。
上記平均電気陰性度によって、Ａｇと第３保護層との分極状態が表現され、この分極が大きいと、水分（Ｈ_２Ｏ）が界面に入り込む結果、Ａｇと第３保護層の膜浮きを促進すると考えられる。
【００３２】
第３保護層は、前述のようにＳｉを含有する必要があり、Ａｇ系光反射層の信頼性を確保するためには、Ｓｉを３５モル％以上含有する必要がある。更にＳｉのモル濃度を高くすると効果的である。しかし、第３保護層は、熱膨張係数、弾性率、化学反応性などの観点から、下地となる第２保護層とのマッチングを考慮しなければならないため、第２保護層の材料によっては、ＳｉにＣ、Ｏ、Ｎなどを添加することも効果的である。
また、他の層に比べて薄い膜である第３保護層でも、媒体特性に与える光学特性の影響は無視できない。Ｓｉは、信頼性という観点からは良好であるが、幾分光吸収能を持っており、あまり厚くすると高い反射率を獲得するためにＡｇ系光反射層を設ける意味が無くなってしまう。
【００３３】
第２保護層がＺｎＳ・ＳｉＯ_２（２０モル％）からなる場合の第３保護層の材料としては、Ｓｉ、ＳｉＣ又はＳｉＣにＯを添加した、ＳｉとＣ（炭素）とＯ（酸素）からなる材料が効果的であり、特にＳｉＣを主成分とするＳｉＯｘとの混合物又はＳｉＣを主成分とするＣ（炭素）及びＳｉＯｘとの混合物が好ましい。
ＳｉＣは融点が極めて高く熱的に安定で且つ緻密であるという特性を持つため膜厚を薄くしても第２誘電体層に含まれる硫黄と反射層のＡｇとの反応を抑えることができるという優れた特性を有するが、高硬度でありＡｇと反応しないために密着性が劣るという欠点を有する。
これに対し、本発明のように、第３保護層にＳｉとＣ（炭素）とＯ（酸素）からなる材料を用いれば、密着性が著しく向上し、腐食が著しく低減される。
【００３４】
第３保護層の膜厚は、Ａｇ系光反射層に期待される高反射率、高熱伝導率に大きな影響を与えない膜厚に設定する。また、第２保護層に期待される記録・消去の際の熱変形への柔軟な対応、記録感度のコントール機能、記録層の非晶質を結晶化させる大口径ＬＤによる初期化状態のコントロール機能への悪影響が無いように設定する。
本発明者等の検討では、これらの諸点を考慮すると、第３保護層の膜厚ＤＭを２〜９ｎｍの範囲にすることにより、効果的に記録消去の信号特性を維持し、かつＡｇ系光反射層の信頼性を確保できることが分った。
２ｎｍ以上あれば連続量産時の繰り返し製膜再現性及び面内均一性が保証でき表面改質の機能を発揮する。好ましくは３〜７ｎｍであり、この範囲であれば、光記録媒体の基本的な光学設計、熱設計を大幅に変えることなく、Ａｇ系光反射層の信頼性を大幅に改善できる。
【００３５】
具体的には、１４ｍ／ｓｅｃでのＤＶＤ＋ＲＷフォーマットによるオーバーライト１０００回後のジッターが８％以下と良好になる。一方、９ｎｍを越えると、表面改質層というよりは、特開平１１−２３８２５３号公報や特開２０００−３３１３７８号公報に開示されているような中間層となってしまい、表面を改質するだけでなく中間層としての物性が、光記録媒体の特性に影響する膜厚領域となってくるので、光学設計、熱設計を大幅に変更する必要を生じてしまう。また、第３保護層（表面改質層）自身に内部応力が発生するようになり、ヒートサイクルでクラック等により破壊されてしまうことも分った。
【００３６】
また、第２保護層の膜厚をＤ２、第３保護層の膜厚をＤＭ、光反射層の膜厚をＤＲとしたとき、下記の条件を満足するようにすれば、より効果的に記録消去の信号特性を維持し、かつＡｇ系光反射層の信頼性を確保できることも分った。
０．１≦ＤＭ／Ｄ２≦０．５、かつ、
０．０１≦ＤＭ／ＤＲ≦０．１
更に、上記条件を下記の範囲にすれば、１４ｍ／ｓｅｃでのＤＶＤ＋ＲＷフォーマットによるオーバーライト１０００回後のジッターが８％以下と良好になることも分った。
０．１５≦ＤＭ／Ｄ２≦０．３５、かつ、
０．０３≦ＤＭ／ＤＲ≦０．０５
【００３７】
第３保護層の作製方法としては、スパッタリング、プラズマＣＶＤ、プラズマ処理、イオンプレーティング、光ＣＶＤなどが利用可能であるが、光記録媒体において汎用されているスパッタリングが効果的である。その代表的作製条件は、圧力１０^−２〜１０^−４Ｐａ、スパッタ電力０．５〜５．０ｋＷ／２００ｍｍφ、製膜速度０．５〜５．０ｎｍ／ｓｅｃである。ここで重要なことは、第３保護層の製膜速度をＲｍ、光反射層の製膜速度をＲｒとしたとき、
０．０２≦Ｒｍ／Ｒｒ≦０．２０
０．５ｎｍ／ｓｅｃ≦Ｒｍ≦５．０ｎｍ／ｓｅｃ
とすることである。
また、ＳｉとＣ（炭素）とＯ（酸素）からなる膜を作成するためには、ＳｉＣとＳｉＯｘの混合物ターゲットを用いたスパッタリング、又はＳｉＣターゲット、及び、Ａｒと、Ｏ_２、ＣＯ、ＣＯ_２から選ばれた少なくとも１種との混合ガスを用いた反応性スパッタリングが特に有効である。
そして、例えばＡｒとＣＯ_２との混合ガスを用いた場合には、表１に示すように、ＡｒとＣＯ_２の流量比を変えることにより第３誘電体層の含有酸素量を制御することができる。
【００３８】
これは、第３保護層を構成する原子が膜に入射する頻度よりも、その上に形成されるＡｇ系光反射層を形成するときのＡｇの入射頻度の方を５〜５０倍大きくすることにより、第３保護層の最表面温度が高くなり、第３保護層の結合の弱い部分がなくなると共に、Ａｇ原子が第３保護層に入り込み、第３保護層が冷却されたときにＡｇ原子が楔のような状態で残って、Ａｇ系光反射膜と第３保護層の膜密着力の向上を図ることが出来るためである。
第３保護層の製膜速度は、０．５〜５．０ｎｍ／ｓｅｃが望ましい。０．５ｎｍ／ｓｅｃ以上とすると、第３保護層へのガスの取り込みが少なくなり緻密な膜になるし、５ｎｍ／ｓｅｃ以下とすると、膜厚のディスク間バラツキが小さくなり、９ｎｍ以下の薄膜を再現性よく製造することが可能になる。
【００３９】
また、第３保護層のスパッタ製膜電力をＰｍ、光反射層のスパッタ製膜電力をＰｒとしたときに、
１．５×Ｐｍ≦Ｐｒ
とすることによっても、上記製膜速度の条件を満足する場合と同様の理由により、Ａｇ系光反射膜と第３保護層の膜密着力の向上を図ることが出来る。
また、この場合、第３保護層の表面温度が高くなるだけでなく、Ａｇ系光反射層の形成時のスパッタ電力が１．５倍以上であることから、エネルギーの大きいイオンの入射頻度も高くなるので、効果的に第３保護層の結合の弱い部分を除去することができ、Ａｇ系光反射層との密着力を向上させることが出来る。
上記光反射層のスパッタ製膜電力Ｐｒの上限は、スパッタ装置の装置仕様上限になる。つまり、装置として安定にスパッタが可能な上限電力となり、現実には１０ｋＷ位である。
【００４０】
以下、実施例により本発明を具体的に説明するが、本発明はこれらの実施例により限定されるものではない。
【００４１】
実施例１
溝幅０．２５μｍ、溝深さ２７ｎｍ、ウオブル溝の周期４．２６μｍの案内溝を有する厚さ０．６ｍｍのポリカーボネート基板を射出成型し、この基板上に、第１保護層、光記録層、第２保護層、第３保護層、及び純度９９．９９重量％のＡｇ光反射層を順次スパッタリング法により積層した。
第１保護層及び第２保護層にはＺｎＳ・ＳｉＯ_２（２０モル％）を用い、膜厚はそれぞれ８０ｎｍ、１４ｎｍとした。
光記録層にはＧａ_３Ｇｅ_３Ｍｎ_４Ｓｂ_７０Ｔｅ_２０を用い、厚さ１６ｎｍとした。
第３保護層には、厚さ４ｎｍのＳｉ膜を用いた。Ｓｉの電気陰性度は１．８であり、Ａｇの電気陰性度１．９より小さい材料を選択した。
Ａｇ光反射層は、厚さ１４０ｎｍとした。
第１保護層、光記録層、第２保護層、第３保護層、Ａｇ光反射層の製膜速度は、それぞれ９ｎｍ／ｓｅｃ、５．６ｎｍ／ｓｅｃ、４．５ｎｍ／ｓｅｃ、１．５ｎｍ／ｓｅｃ、３２ｎｍ／ｓｅｃ、同じく製膜スパッタ電力は、それぞれ４ｋＷ、０．４ｋＷ、１．５ｋＷ、１．５ｋＷ、３．５ｋＷとした。
以上の結果、ポリカーボネート基板／ＺｎＳ・ＳｉＯ_２（８０ｎｍ）／Ｇａ_３Ｇｅ_３Ｍｎ_４Ｓｂ_７０Ｔｅ_２０（１６ｎｍ）／ＺｎＳ・ＳｉＯ_２（１４ｎｍ）／Ｓｉ（４ｎｍ）／９９．９９重量％Ａｇ（１４０ｎｍ）という積層構成を形成した。
次いで、Ａｇ光反射層上に、室温粘度１２０ｃｐｓ、硬化後のガラス転移温度１４９℃となる紫外線硬化型樹脂をスピンコートして樹脂保護層を形成し、相変化型光記録媒体の単板ディスクを作成した。
次いで、ポリカーボネート製の貼り合わせ基板を、室温粘度５８０ｃｐｓ、硬化後のガラス転移温度１３５℃となる紫外線硬化型接着剤で貼り合わせて、図１のようなＤＶＤタイプの構成の光記録媒体を得た。
【００４２】
次に、大口径ＬＤ（ビーム径２００×１μｍのレーザーダイオード）を有する初期化装置によって、線速度３．５ｍ／ｓｅｃ、電力（ＬＤパワー）８５０ｍＷ、送り１２０μｍで、内周から外周に向けて、線速度一定で全面結晶化した。
続いて、得られた相変化型光記録媒体に、記録線速度１６．７５ｍ／ｓｅｃ、波長６５０ｎｍ、ＮＡ０．６５、記録パワー１４．５ｍＷで、ＤＶＤ−ＲＯＭ再生可能なフォーマットで光記録した。
その結果、、ダイレクトオーバーライト（ＤＯＷ）１０００回記録後のＤａｔａ ｔｏ Ｃｌｏｃｋ Ｊｉｔｔｅｒ（データ・トゥー・クロック・ジッター）が７．５％と良好であった。また、反射率２０％、変調度６３％と信号特性も良好であり、Ａｇ本来の高い光反射率、高い熱伝導率を効率的に利用できた。
更に、この光記録媒体について、温度の昇降速度１０℃／時間で、２５℃９５％ＲＨ１２時間−４０℃９５％ＲＨ１２時間の条件で６回のヒートサイクル試験を行った結果、反射率２０％、変調度６３％、外周５８ｍｍのチルト０．４°と変化は認められなかった。また、欠陥率の増大も認められなかった。
【００４３】
実施例２〜１３
溝幅０．２５μｍ、溝深さ２７ｎｍ、ウオブル溝の周期４．２６μｍの案内溝を有する厚さ０．６ｍｍのポリカーボネート基板を射出成型し、この基板上に、第１保護層、光記録層、第２保護層、第３保護層、及び純度９９．９９重量％のＡｇ光反射層を順次スパッタリング法により積層した。
第１保護層及び第２保護層にはＺｎＳ・ＳｉＯ_２（２０モル％）を用い、光記録層にはＧａ_３Ｇｅ_３Ｍｎ_４Ｓｂ_７０Ｔｅ_２０を用い、第３保護層には、下記表２に示す材料を用いた。このときの、各層の膜厚と製造条件を表２に示す。
次いで、Ａｇ光反射層上に、室温粘度１２０ｃｐｓ、硬化後のガラス転移温度１４９℃となる紫外線硬化型樹脂をスピンコートして環境保護層を形成し、相変化型光記録媒体の単板ディスクを作成した。
次いで、ポリカーボネート製の貼り合わせ基板を、室温粘度５８０ｃｐｓ、硬化後のガラス転移温度１３５℃となる紫外線硬化型接着剤で貼り合わせて、図１のようなＤＶＤタイプの構成の光記録媒体を得た。
【００４４】
次に大口径ＬＤ（ビーム径２００×１μｍのレーザーダイオード）を有する初期化装置によって、線速度３．５ｍ／ｓｅｃ、電力（ＬＤパワー）８５０ｍＷ、送り１２０μｍで、内周から外周に向けて、線速度一定で全面結晶化した。
次に、得られた相変化型光記録媒体に、記録線速度１６．７５ｍ／ｓｅｃ、波長６５０ｎｍ、ＮＡ０．６５、記録パワー１４．５ｍＷで、ＤＶＤ−ＲＯＭ再生可能なフォーマットで光記録した。
その結果、第３保護層厚２〜９ｎｍでは、ＤＯＷ１０００回後のジッター９％以下と良好であった。更に、３〜７ｎｍでは、ＤＯＷ１０００回後のジッター８％以下とより良好であった。また、反射率２０％、変調度６３％と信号特性も良好であり、Ａｇ本来の高い光反射率、高い熱伝導率を効率的に利用できた。
更に、この光記録媒体を、８０℃８５％ＲＨ５００時間の保存試験、及び温度の昇降速度１０℃／時間で、２５℃９５％ＲＨ１２時間−４０℃９５％ＲＨ１２時間の６回のヒートサイクル試験を行った結果、下記表２に示したように、欠陥率の増大及びエラーの顕著な増大は認められなかった。
【００４５】
比較例１〜７
第３保護層の材料と膜厚を下記表２記載のものに変えた点以外は、実施例２〜１３の場合と同様にして光記録媒体を作成し、実施例２〜１３の場合と同様にして試験を行った。その結果を表２に示す。
表２から分るように、比較例１は第３保護層を設けなかった例であり、比較例２〜７は、第３保護層の材料は本発明の要件（Ｓｉ原子を３５モル％以上含む）を満たしているが、膜厚が１ｎｍ又は１０ｎｍであって、２〜９ｎｍという本発明の範囲を外れている。そのため、何れも、ＤＯＷ１０００回後のジッター、５００時間保存後のジッター、サイクル後のジッターの少なくとも一つに問題があり、総合判定としてＮＧのものしか得られなかった。
【００４６】
【表２】

【００４７】
実施例１４〜１８、比較例８〜１０
溝幅０．２５μｍ、溝深さ２７ｎｍの案内溝を有する厚さ０．６ｍｍのポリカーボネート基板を射出成型し、この基板上に、第１保護層、記録層、第２保護層、第３保護層、及び純度９９．９９重量％のＡｇ光反射層を順次スパッタリング法により積層した。
第１保護層及び第２保護層にはＺｎＳ・ＳｉＯ_２（２０モル％）を用い、膜厚はそれぞれ８０ｎｍ、１４ｎｍとした。
記録層にはＧｅ_２．０Ａｇ_０．５Ｉｎ_５．０Ｓｂ_６８．５Ｔｅ_２４．０を用い、厚さ１６ｎｍとした。
第３保護層としては、ＳｉＣターゲット及び表３に示す流量比の混合ガスを用い、圧力０．５Ｐａ、パワー１ｋＷの条件でスパッタリングして、厚さ４ｎｍの膜を形成した。
Ａｇ光反射層は、厚さ１４０ｎｍとした。
その結果、ポリカーボネート基板／ＺｎＳ・ＳｉＯ_２（８０ｎｍ）／Ｇｅ_２．０Ａｇ_０．５Ｉｎ_５．０Ｓｂ_６８．５Ｔｅ_２４．０（１６ｎｍ）／ＺｎＳ・ＳｉＯ_２（１４ｎｍ）／ＳｉＣ（４ｎｍ）／Ａｇ（１４０ｎｍ）という積層構成を形成した。
次いで、Ａｇ光反射層上に、室温粘度１２０ｃｐｓ、硬化後のガラス転移温度１４９℃となる紫外線硬化型樹脂をスピンコートしてオーバーコート層を形成し、相変化型光記録媒体の単板ディスクを作製した。
更に、ポリカーボネート製のカバー基板を、紫外線硬化型接着剤で貼り合わせて、図１の構成の光記録媒体を得た。
【００４８】
次に、大口径ＬＤ（ビーム径２００×１μｍ）を有する初期化装置によって、線速度３．０ｍ／ｓｅｃ、電力（ＬＤパワー）８５０ｍＷ、送り１００μｍで、内周から外周に向けて、線速度一定で全面結晶化した。
続いて、得られた相変化型光記録媒体に、記録線速度８．５ｍ／ｓｅｃ、波長６５０ｎｍ、ＮＡ０．６５、記録パワー１４ｍＷで、ＤＶＤ−ＲＯＭ再生可能なフォーマットで光記録した。
その結果、表３に示すように、ＤＯＷ記録後のＤａｔａ ｔｏ Ｃｌｏｃｋ Ｊｉｔｔｅｒが９％以上となる回数は第３誘電体層に含まれる酸素量が２０％以下の場合であった。酸素量２０％を越えるとオーバーライトにより第３誘電体のクラック及び反射層の剥離が生じた。また、酸素量ゼロでは８０℃８５％３００時間の保存テスト後のエラー増加率〔（保存後のエラー−初期エラー）／初期エラー〕が１０％を大きく超えるため一部データを読み取ることができなかったが、酸素量１原子％以上では増加率が１０％以下となり、保存テスト後でも問題なく再生できた。
また、実施例１７の光記録媒体のオージェデプスプロファイル（オージェ電子分光深さ方向分析）を測定したところ、図５のような結果が得られ、膜中にＳｉより過剰なＣ（炭素）が取り込まれていることが確認された。
なお、オージェデプスプロファイルとは、高エネルギー（１〜５ｋｅＶ）電子を照射して物質表面から放出される物質固有のエネルギーを有するオージェ電子を分光することにより組成比を定量する方法である。
【００４９】
【表３】

【００５０】
【発明の効果】
本発明によれば、Ａｇ系光反射層の高反射率、高熱伝導率を活用し、光学設計、熱設計に大きな影響を与えることなく、Ａｇのイオン化及びＡｇのボイド生成が抑制され、Ａｇ光反射層と第３保護層の密着力が向上した、高温高湿保存時でも信頼性の高い光記録媒体、及びその製造方法を提供できる。
【図面の簡単な説明】
【図１】本発明に係るＤＶＤタイプの光記録媒体の一例を示す図。
【図２】本発明に係るＣＤタイプの光記録媒体の一例を示す図。
【図３】ＤＶＤ＋ＲＷ媒体のヒートサイクル信頼性の、第３保護層材料のＳｉ含有率依存性を示す図。
【図４】ＤＶＤ＋ＲＷ媒体のヒートサイクル信頼性の、第３保護層材料の平均電気陰性度依存性を示す図。
【図５】実施例１７の光記録媒体のオージェデプスプロファイルを測定した結果を示す図。
【符号の説明】
１ 基板
２ 第１保護層
３ 光記録層
４ 第２保護層
５ 第３保護層
６ 光反射層
７ 樹脂保護層
８ 接着層
９ カバー基板
１０ 印刷層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical recording medium such as CD-R, CD-RW, DVD-ROM, DVD-R, DVD-RW, DVD + R, DVD + RW, DVD-RAM, etc., capable of reproducing or recording information by laser light irradiation. Thus, the present invention relates to an optical recording medium capable of high-speed recording, particularly 12 m / sec (seconds) or higher.
[0002]
[Prior art]
CD-DA, CD-ROM, VIDEO-CD, CD-R, CD-RW, DVD-VIDEO, DVD-ROM, DVD-R, DVD-RW are optical recording media that can be reproduced or recorded by laser light irradiation. DVD + R, DVD + RW, DVD-RAM, etc. are commercialized. These recording media are expected to further increase the recording density and the linear velocity so that more information can be recorded more quickly. As a solution, an Ag-based light reflecting layer is used. Is being considered.
When Ag is used as a light reflection layer of an optical recording medium, the following advantages are expected. However, in order to ensure these merits, it is desirable to use Ag having a purity of 95% by weight or more.
(1) Improvement of reproduction capability by increasing disc reflectivity over a wide wavelength range
(2) Improvement of reproduction capability by increasing signal amplitude due to optical characteristics of Ag
(3) In the case of the light reflection layer of the phase change disk, the overwrite performance is improved by the layer structure with a faster cooling rate.
(4) In the case of the light reflection layer of the phase change disk, the recordable linear velocity range is expanded by the layer structure having a higher cooling rate.
(5) Productivity improvement due to high sputtering efficiency
(6) Reduction of thermal stress by shortening sputter deposition time (improvement of disk mechanical properties)
[0003]
On the other hand, when Ag is used as a light reflection layer of an optical recording medium, there are the following problems.
(1) Easily corroded under high temperature and high humidity.
(2) Easily corroded by sulfur and chlorine.
(3) The film adhesion with the substrate is small.
(4) It is a noble metal and expensive compared to Al or the like of a general-purpose reflective layer.
As a method for suppressing corrosion of Ag, AgCu in JP-A-57-186244, AgMg in JP-A-7-3363, AgOM in JP-A-9-156224 (M: Sb, Pd, Pt), An alloying of Ag such as found in AgPdCu in JP-A-2000-285517 is known. Patent 2749080 discloses that in order to control the thermal conductivity, Ag, Ti, V, Fe, Co, Ni, Zn, Zr, Nb, Mo, Rh, Pd, Sn, Sb, Te, Ta, It is disclosed that W, Ir, Pt, Pb, Bi, and C are contained.
However, when these material systems were actually used for the light reflection layer, DVD + R discs and DVD + RW discs were produced, and the archival high-temperature storage reliability at 80 ° C. and 85% RH of these optical recording media was evaluated. A rapid increase in errors was observed in the storage of time, and the above disclosed materials could not provide sufficient storage reliability.
[0004]
As a means for suppressing corrosion of the reflective layer, conventionally, an ultraviolet curable resin layer is formed on the surface of the reflective layer. For example, Japanese Patent Laid-Open No. 2001-222842 discloses that by setting the glass transition temperature of the resin to 45 ° C. or higher, wrinkles due to water absorption of the resin are eliminated, and corrosion of the Al reflective layer can be avoided. However, in the experiments by the present inventors, even when the resin having a glass transition temperature of 80 ° C. disclosed in the above publication was used, corrosion or an increase in reproduction error occurred in the case of the Ag-based light reflection layer.
In the phase change type optical recording medium, ZnS · SiO is formed above and below the recording layer.₂It is effective to form a (20 mol%) film. For this material, a material with optimized thermal expansion coefficient, optical constant, and elastic modulus is used.
However, when an Ag-based light reflection layer is used for high-speed recording of a phase change optical recording medium, ZnS · SiO₂When an Ag-based light reflection layer is formed directly on the Ag, Zn and ZnS · SiO₂It is known that the S reacts to cause corrosion of the reflective layer.
[0005]
As a countermeasure, JP-A-11-238253 discloses Ta, Ni, Co, Cr, in order to prevent a chemical reaction between the sulfur atom in the protective layer of the phase change optical recording medium and the Ag-based light reflection layer. It is disclosed that an intermediate layer using Si, W, V, C, Si, Au, Pd, Ag oxide, Al oxide, and Ta oxide is provided. It is described that 40 nm is preferable in order to effectively use the high thermal conductivity of the system light reflecting layer, and that the signal characteristics and storage reliability at 80 ° C. and 85% RH are not a problem when the intermediate layer thickness is 10 to 50 nm. Yes.
However, when the present inventors produced a phase change type optical recording medium using these materials as an intermediate layer, the dependence of the signal characteristics on the intermediate layer thickness is large and practical when the intermediate layer thickness is 10 to 50 nm. No signal quality was obtained. In addition, in six heat cycle tests between 25 ° C. and 95% RH for 12 hours and 40 ° C. and 95% RH for 12 hours at a temperature raising / lowering rate of 10 ° C./hour, the Ag-based light reflection layer is peeled off from the intermediate layer. Problems also occurred.
That is, according to the examination results of the present inventors, although the reaction between sulfur and Ag in the protective layer is suppressed by the formation of the intermediate layer, the adhesion between the intermediate layer and the Ag-based light reflection layer is not sufficient. It was found that the film adhesion strength of the film decreased due to high humidity and condensation. This is because, as a result of suppressing the corrosion of the Ag-based light reflection layer by providing a chemically inert intermediate layer to suppress mutual diffusion, the film adhesion between the intermediate layer and the Ag-based light reflection layer, in particular, the film due to humidity This is thought to be because it was impossible to suppress the decrease in adhesion.
[0006]
In addition, Japanese Patent Application Laid-Open No. 2000-331378 related to the prior application of the present applicant describes AlN, SiNx, SiAlN, TiN, BN, TaN, Al as an upper dielectric protective layer in contact with the reflective heat dissipation layer.₂O₃, MgO, SiO, TiO₂, B₂O₃, CeO₂, CaO, Ta₂O₅, ZnO, In₂O₃, SnO₂, WC, MoC, TiC, SiC, the upper dielectric protective layer may be a multilayer, and the upper dielectric layers 4 and 5 (corresponding to the positions of the second and third protective layers of the present invention). It is disclosed that the total film thickness is 7 to 60 nm, preferably 10 to 30 nm.
However, as an example, only an example in which the film thickness of the upper dielectric protective layer 2 corresponding to the position of the third protective layer of the present invention is 10 nm thicker than the numerical limited range of the present invention is shown. There is no example of 9 nm or less. In addition, in the upper dielectric protective layer composed of two layers, the reflection and heat dissipation is further improved in order to greatly improve the reliability of the Ag-based light reflection layer without significantly changing the basic optical design and thermal design of the optical recording medium. In order to prevent corrosion of Ag without adversely affecting the function of the protective layer that is not in contact with the layer (second protective layer in the present invention), the protective layer that is in contact with the reflective heat dissipation layer (third protective layer in the present invention) ) Is not disclosed in this prior application gazette.
[0007]
Moreover, as will be described later, even when a material containing 35 mol% or more of Si atoms is used as the material of the third protective layer, the initial signal characteristics and reliability under high humidity of 95% RH are obtained when the film thickness becomes 10 nm. (Refer to Comparative Examples 3 to 7 in Table 2), and other materials other than materials (SiO, SiC, etc.) containing 35 mol% or more of Si atoms equally treated in this prior application are used. Even if the third protective layer having a thickness of 9 nm or less is provided, the same effect as the present invention cannot be obtained (see Experiments 1 and 16 in Table 1).
Therefore, in the publication of the prior application, among the many materials for the upper dielectric layer exemplified, only the material containing 35 mol% or more of Si atoms has an excellent effect selectively as compared with other materials. Can be said to be neither described nor suggested.
[0008]
In short, although the above-mentioned JP-A-11-238253 and JP-A-2000-331378 describe that an intermediate layer or a dielectric protective layer uses Si or a material containing Si, It is described as one of the equivalents together with many other materials including those listed as comparative examples in the invention, and the inherent effect that only the material containing 35 mol% or more of Si atoms selectively has Is neither described nor suggested, and the film thickness range in which the object of the present invention cannot be achieved because the film thickness is thicker than the numerical limit range (2 to 9 nm) of the present invention. It is apparent that the technical idea of the present invention is not disclosed.
In addition, these publications include clear sputtering conditions for intermediate layers or dielectric protective layers containing Si, film structures that depend on those conditions, film quality, and environmental reliability and recording signal characteristics based on the film quality. The optimum film thickness based on the balance is not disclosed at all.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to provide an optical recording medium having high storage reliability under high temperature and high humidity, stable high temperature operation, good mechanical properties, high productivity, and capable of high speed reproduction or high speed recording.
[0010]
[Means for Solving the Problems]
  The above-mentioned problems are as follows:18).
  1) On the substrate, at least a first protective layer, an optical recording layer, and a second protective layerThe second3 An optical recording medium having a protective layer and a light reflecting layer made of a material containing 95% by weight or more of Ag in this order, and further having a resin protective layer and / or an adhesive layer on the light reflecting layer.The second protective layer is made of ZnS and SiO. ₂ The second protective layer has a thickness in the range of 5 to 45 nm, and the third protective layer is a material composed of Si, C and O (containing 35 mol% or more of Si atoms and O atoms). 1 to 20 atom%), SiC (containing 35 mol% or more of Si atoms), and Si alone,An optical recording medium, wherein the third protective layer has a thickness DM in the range of 2 to 9 nm.
  2) The optical recording medium according to 1), wherein the thickness DM of the third protective layer is in the range of 3 to 7 nm.
  3) When the thickness of the second protective layer is D2, the thickness of the third protective layer is DM, and the thickness of the light reflecting layer is DR,
      0.1 ≦ DM / D2 ≦ 0.5 and 0.01 ≦ DM / DR ≦ 0.1
1) characterized byOr 2)The optical recording medium described.
  4) 0.15 ≦ DM / D2 ≦ 0.35 and 0.03 ≦ DM / DR ≦ 0.053)The optical recording medium described.
  5) When the third protective layer has an average electronegativity of En (ave), the molar concentration (%) of the constituent element is mi, and the electronegativity of the constituent element is Eni,
              En (ave) = (Σmi × Eni) /100≦2.3
1) to characterized by comprising an amorphous material4)An optical recording medium according to any one of the above.
  6) The glass transition temperature of the resin protective layer and / or the adhesive layer on the light reflection layer is 90 to 180 ° C. 1) to5)An optical recording medium according to any one of the above.
  7) The glass transition temperature is 100 to 165 ° C.6)The optical recording medium described.
  8) It has a resin protective layer and an adhesive layer on the light reflection layer, and the difference in glass transition temperature between the two layers is 50 ° C. or less.7)An optical recording medium according to any one of the above.
  9) The difference in glass transition temperature is 30 ° C. or less.8)The optical recording medium described.
  10) The light reflecting layer added at least one element selected from Al, Bi, Ca, Cu, Cd, Fe, Mn, Mg, Ni, Pd, Pb, Sb, Zn, and Nd to Ag. 1) to characterized by comprising material9)An optical recording medium according to any one of the above.
  11) Elements added to Ag are Cu and Nd10)The optical recording medium described.
  12) The width of the guide groove formed on the substrate is 0.10 to 0.40 μm and the depth is 15 to 45 nm (a DVD-ROM compatible rewritable optical recording medium) 1) ~11)An optical recording medium according to any one of the above.
  13) The guide groove has a width of 0.15 to 0.35 μm and a depth of 20 to 40 nm.12)The optical recording medium described.
  14) The width of the guide groove formed on the substrate is 0.25 to 0.65 μm, and the depth is 20 to 50 nm (CD-RW medium) 1) to13)An optical recording medium according to any one of the above.
  15) The guide groove has a width of 0.30 to 0.60 μm and a depth of 25 to 45 nm.14)The optical recording medium described.
  16) When the deposition rate of the third protective layer is Rm and the deposition rate of the light reflecting layer is Rr, both layers are
              0.02 ≦ Rm / Rr ≦ 0.20
              0.5 nm / sec ≦ Rm ≦ 5.0 nm / sec
The film is formed under the conditions 1) to15)A method for producing an optical recording medium according to any one of the above.
  17) When the sputtering deposition power of the third protective layer is Pm and the sputtering deposition power of the light reflecting layer is Pr, both layers are
              1.5 × Pm ≦ Pr
The film is formed under the conditions 1) to15)A method for producing an optical recording medium according to any one of the above.
  18)In the case where the third protective layer is made of a material composed of Si, C and O (containing 35 mol% or more of Si atoms and 1 to 20 atomic% of O atoms),The third protective layer is made of SiC target, Ar, and O.₂, CO, CO₂By reactive sputtering using a mixed gas with at least one selected fromFilm formationIt is characterized by1) -15)A method for producing an optical recording medium according to any one of the above.
[0011]
Hereinafter, the present invention will be described in detail.
An example of the form of the present invention is shown in FIGS. The basic structure is that a first protective layer 2, an optical recording layer 3, a second protective layer 4, a third protective layer 5, a light reflecting layer 6, a resin protective layer (overcoat layer) are formed on a substrate 1 having guide grooves. ) 7, and if necessary, a printed layer 10 may be formed on the surface, or a hard coat layer may be formed on the reproduction light incident surface (substrate mirror surface) for the purpose of improving scratch resistance. .
Further, in the case of a DVD type optical recording medium, a laminated structure may be used via the adhesive layer 8. The disc on the opposite side to be bonded may be a similar single plate disc or only the cover substrate (transparent substrate) 9.
Further, after bonding to a single disk disk without forming a print layer, the print layer may be formed on the opposite surface side. Furthermore, the resin protective layer and the adhesive layer can be combined to form a single layer.
[0012]
The material of the substrate is usually glass, ceramics or resin, and a resin substrate is preferable in terms of moldability and cost.
Examples of such resins include polycarbonate resin, acrylic resin, epoxy resin, polystyrene resin, acrylonitrile-styrene copolymer resin, polyethylene resin, polypropylene resin, silicone resin, fluorine resin, ABS resin, urethane resin, and the like. Although mentioned, the polycarbonate resin and acrylic resin which were excellent in the moldability, the optical characteristic, and the point of cost are preferable.
However, 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 are given. That is, the width of the guide groove formed on the substrate to be used is 0.10 to 0.40 μm, preferably 0.15 to 0.35 μm, and the depth of the guide groove is 15 to 45 nm, preferably 20 to 40 nm. It is that. Such a substrate groove improves reproduction compatibility with a DVD-ROM drive.
The thickness of the substrate is preferably 0.55 to 0.65 mm, and the thickness of the disk after bonding is preferably 1.1 to 1.3 mm.
Further, when the optical recording medium of the present invention is applied to a CD-RW medium, the width of the guide groove is 0.25 to 0.65 μm, preferably 0.30 to 0.60 μm, and the depth of the guide groove is set. 20 to 50 nm, preferably 25 to 45 nm.
[0013]
As a material of the first protective layer and the second protective layer, ZnS · SiO₂(15 mol%), ZnS.SiO₂(20 mol%), ZnS.SiO₂ZnS and SiO such as (25 mol%)₂Substances containing are effective. In addition, SiO, SiO₂ZnO, SnO₂, Al₂O₃TiO₂, In₂O₃, MgO, ZrO₂Oxides such as Si;₃N₄Nitrides such as AlN, TiN, BN, ZrN; ZnS, TaS₄Sulfides such as SiC, TaC, B₄Carbides such as C, WC, TiC, and ZrC; diamond-like carbon, or a mixture thereof can also be used.
In particular, as a protective layer with thermal damage due to thermal expansion change or high temperature / room temperature change located above and below the phase change optical recording layer, the optical constant, thermal expansion coefficient, and elastic modulus are optimized.₂(20 mol%) is desirable.
Since the film thickness of the first protective layer greatly affects the reflectivity, the degree of modulation, and the recording sensitivity, it is preferably 60 to 120 nm in order to obtain good signal characteristics.
The film thickness of the second protective layer is 5 to 45 nm, preferably 7 to 40 nm. When it is thinner than 5 nm, the function as a heat-resistant protective layer is not achieved, and the recording sensitivity is lowered. On the other hand, if it is thicker than 45 nm, interfacial delamination tends to occur, and repeated recording performance also deteriorates.
[0014]
The optical recording layer includes SbTe that undergoes a phase change between a crystal and an amorphous phase, each of which can be in a stabilized or metastable state, and the composition ratio thereof is Sb_χTe_100-χPhase change type optical recording material (χ is atomic%, 40 ≦ χ ≦ 80) is suitable because of good recording (amorphization) sensitivity / speed, erasure (crystallization) sensitivity / speed, and erasure ratio. . Furthermore, the phase-change optical recording layer is not only capable of recording / erasing, but is also required to have signal reproduction stability and signal life (reliability) when recording in a high density and high linear velocity region.
As a phase change type optical recording layer that can satisfy these conditions comprehensively, GeSbTe, AgInSbTe, GeInSbTe, etc. containing SbTe as a main component have been commercialized.
[0015]
However, in order to record at a high speed of 10 m / sec or more, the composition formula is (Ag and / or Ge) α (In and / or Ga and / or Bi) βSbγTeδMε (where M is an additive element, α, β , Γ, δ, and ε are atomic% and α + β + γ + δ + ε = 100), and a phase change optical recording material that satisfies the following conditions is excellent.
0.1 ≦ α ≦ 10
1 ≦ β ≦ 15
60 ≦ γ ≦ 90
15 ≦ δ ≦ 30
0 ≦ ε ≦ 10
In the composition region satisfying these conditions, high-speed recording / erasing of 10 m / sec or more is possible, and CAV (constant angular velocity) recording with a recording speed 2.4 times different between the inner circumference and the outer circumference is possible.
As the additive element M, adding a metal having a lower thermal conductivity than the metal Sb is effective in reducing the recording power, which is a problem in high-speed recording. Specific examples of such metals include lanthanum series metals such as Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, and Ho, Ti, Zr, and Mn.
The addition amount of the additive element M is preferably 10 atomic% or less. If it exceeds 10 atomic%, the recording / erasing characteristics are affected, and the overwriting performance becomes insufficient.
[0016]
A cubic lattice crystal structure in which the crystal structure in an unrecorded state after initialization is an isotropic crystal structure, preferably a material having a NaCl-type crystal structure, and an amorphous phase which is considered to be highly isotropic It is suitable because it can cause a phase change with little variation and can perform recording (amorphization) and erasing (crystallization) at high speed and uniformly.
The film thickness of the phase change optical recording layer is 10 to 50 nm, preferably 12 to 30 nm. Furthermore, considering initial characteristics such as jitter, overwrite characteristics, and mass production efficiency, the thickness is preferably set to 13 to 25 nm. If it is thinner than 10 nm, the light absorption ability is remarkably lowered and the role cannot be played. On the other hand, if it is thicker than 50 nm, uniform phase change is difficult to occur at high speed.
Such an optical recording layer can be formed by various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating, and electron beam deposition. Among these, the sputtering method is preferable because it is excellent in mass productivity and film quality.
[0017]
As a result of intensive studies on the problems of the Ag-based light reflection layer described above, as a light reflection layer of an optical recording medium, in order to ensure the light reflectivity and high thermal conductivity that are the characteristics of Ag, Ag having a purity of 95% by weight or more is required. It was necessary to use. However, this Ag-based light reflecting layer having a purity of 95% by weight or more has insufficient high-temperature and high-humidity storage reliability, and film peeling or corrosion of the Ag-based light reflecting layer occurred.
Therefore, as a result of examining the mechanism of film peeling and corrosion, the sulfur source and chlorine source in the resin protective layer and / or the adhesive layer on the Ag-based light reflection layer are moisture (H₂Contact with Ag in the presence of O) was found to corrode Ag. It has been found that the corrosion proceeds by the sulfur source and chlorine source that have reached the surface of Ag infiltrated through the grain boundaries of Ag through moisture.
As countermeasures thereof, at least selected from Al, Bi, Ca, Cu, Cd, Fe, Mn, Mg, Ni, Pd, Pb, Sb, Zn, and Nd, which have excellent compatibility with Ag, with respect to Ag It is effective to add one element, and it is particularly preferable to add Cu and Nd. These additive elements have the effect of preventing the generation of voids accompanying the antioxidant and Ag particle aggregation.
[0018]
However, recent demands for reliability are strong, and it is particularly required to ensure reliability in a high temperature environment. For example, in car use such as a car navigation system, high temperature reliability of about 70 ° C. is expected in consideration of the summer environment. Although reliability of the Ag reflection layer can be improved by alloying Ag as described above, the reliability in an environment of 70 ° C. or higher is not sufficient. The fact that the environmental temperature is 70 ° C. has revealed that the surface of the optical disc inside the actual optical disc reproducing or recording apparatus is 85 to 90 ° C. Therefore, it is required to ensure the reliability of the optical disk at 80 to 90 ° C.
Moreover, since the cost is increased by using an alloy, development of a better countermeasure is desired.
[0019]
As described above, film peeling and corrosion of the Ag-based light reflection layer are strongly affected by moisture, and thus the reliability of the Ag-based light reflection layer is considered to be impaired by the electrochemical action. Therefore, it is presumed that the Ag-based light reflection layer is deteriorated due to electrical deviation, polarization, and ionization of Ag atoms.
From these findings, the present inventors considered that the following (1) to (3) are important in order to improve the reliability of the Ag reflection layer.
(1) Suppressing contact with moisture
(2) Ag is formed on an underlayer that is difficult to polarize and ionize.
(3) To improve the adhesion with the underlying layer by a physical method rather than chemical bonding. Therefore, the following (a) to (b) were examined as countermeasures.
(A) Resin protective layer and / or adhesive layer for suppressing moisture permeation to Ag-based light reflection layer
(B) Third protective layer (surface modified layer) optimal for Ag-based light reflecting layer
[0020]
First, the resin protective layer and / or adhesive layer that suppresses moisture permeation to the Ag-based light reflection layer of (a) will be described.
As a result of intensive investigations on the cause of corrosion and peeling of the Ag reflection layer under high temperature and high humidity, it was found that it depends on the glass transition temperature of the resin protective layer and / or the adhesive layer covering the Ag-based light reflection layer. . That is, the water permeability and linear expansion coefficient of the resin protective layer and / or the adhesive layer increase significantly when the glass transition temperature or higher is reached. As a result, it has been found that the arrival of moisture to the Ag surface, which is the main cause of corrosion of the Ag reflection layer and film peeling, is promoted, and the optical recording medium deteriorates. Therefore, when the reliability of the Ag reflection layer is to be ensured up to the disk temperature of 90 ° C., the glass transition of the resin protective layer and / or the adhesive layer is considered in consideration of a general reliability test of 80 ° C. and 85% RH. It is effective to set the temperature to 90 ° C. or higher. Furthermore, a resin protective layer and / or an adhesive layer having a glass transition temperature of 100 ° C. or higher that theoretically maximizes the water permeation rate is desirable.
However, if the glass transition temperature of the resin protective layer and / or the adhesive layer is too high, the bending strength of the optical recording medium is reduced, and the optical recording medium is easily broken when dropped on the floor or taken out from the plastic case. Produce. Therefore, in order to make the optical recording medium difficult to break, it is desirable that the glass transition temperature of the resin protective layer and / or the adhesive layer is 180 ° C. or lower, preferably 165 ° C. or lower.
[0021]
Moreover, when the resin protective layer and the adhesive layer are adjacent to each other on the Ag reflection layer, the thermal expansion coefficient and the like are greatly different when the difference in the glass transition temperature between the two layers is increased. As a result, the optical recording medium is deformed, warped and tilted, particularly in the circumferential direction, warped and tilted, and an error is likely to occur during reproduction and recording at a high speed of 10 m / sec or more. Therefore, in order to realize stable reproduction and recording at a high speed of 10 m / sec or more, it is necessary to reduce the difference in glass transition temperature between the resin protective layer on the Ag reflection layer and the adhesive layer to about 50 ° C. or less. The temperature is preferably 30 ° C. or lower. As a specific measure, it is also effective to use the same material for the resin protective layer and the adhesive layer.
The glass transition temperature (Tg) is defined as the temperature at which the specific volume, specific heat, refractive index, dielectric constant, diffusion constant, elastic modulus, etc. change suddenly when the resin changes with temperature. The glass transition temperature of the resin is controlled by the intermolecular force resulting from the chemical structure of the starting monomer of the polymer compound constituting the resin, the size of the substituent, the polarity, and the like. This glass transition temperature can be measured from the inflection point of tan δ with a viscoelasticity measuring device.
[0022]
The film thickness of the Ag-based light reflection layer is 50 to 200 nm, preferably 70 to 160 nm. It is also possible to make the Ag-based light reflection layer multi-layered. When multilayered, the thickness of each layer is required to be at least 10 nm, and the total thickness of the multilayered film is preferably 50 to 160 nm. When used as a translucent reflective layer of a multilayer recording layer, 10 to 50 nm is preferable.
The Ag-based light reflection layer can be formed by various vapor deposition methods such as vacuum deposition, sputtering, plasma CVD, photo CVD, ion plating, and electron beam deposition. However, sputtering is desirable as a method for manufacturing an optical recording medium.
[0023]
A resin protective layer (overcoat layer) is formed on the reflective layer to prevent oxidation.
As the resin protective layer, an ultraviolet curable resin layer produced by a spin coating method is suitable. The thickness is suitably 3 to 15 μm, and if it is thinner than 3 μm, an increase in errors may be observed when a printed layer is provided on the resin protective layer and overcoat layer. On the other hand, if it is thicker than 15 μm, the internal stress increases, which greatly affects the mechanical properties of the disk.
[0024]
When providing a hard coat layer, an ultraviolet curable resin produced by a spin coat method is generally used. The thickness is suitably 2 to 6 μm. If it is thinner than 2 μm, sufficient scratch resistance cannot be obtained. If it is thicker than 6 μm, the internal stress increases, which greatly affects the mechanical properties of the disk.
Moreover, the hardness needs to be more than the pencil hardness H which does not give a big damage | wound even if it rubs with a cloth. If necessary, it is also effective to mix a conductive material to prevent electrification and prevent adhesion of dust and the like.
[0025]
The printed layer is used for the purpose of ensuring scratch resistance, label printing such as a brand name, and forming an ink receiving layer for an inkjet printer, and it is preferable to form an ultraviolet curable resin by a screen printing method.
The thickness is suitably 3 to 50 μm. If the thickness is less than 3 μm, unevenness occurs during the formation of the layer, and if the thickness is greater than 50 μm, the internal stress increases, greatly affecting the mechanical properties of the disk.
[0026]
For the adhesive layer, an adhesive such as an ultraviolet curable resin, a hot melt adhesive, or a silicone resin can be used.
Such an adhesive layer material is applied on the overcoat layer or print layer by a method such as spin coating, roll coating, or screen printing, depending on the material, and subjected to treatments such as ultraviolet irradiation, heating, and pressure. After that, the discs on the opposite side are pasted together.
The disk on the opposite surface may be the same single plate disk or a transparent substrate alone, and the adhesive layer material may or may not be applied to the bonding surface of the opposite disk. Moreover, as an adhesive layer, an adhesive sheet can also be used.
The thickness of the adhesive layer is not particularly limited, but it is 5 to 100 μm, preferably 7 to 80 μm, considering the effects of material applicability, curability, and disk mechanical properties.
The range of the adhesive surface is not particularly limited, but when applied to a rewritable disc capable of DVD and / or CD compatibility, in order to enable high-speed recording, it is necessary to ensure the adhesive strength. It is desirable that the position of the peripheral end is Φ15 to 40 mm, preferably Φ15 to 30 mm.
[0027]
Next, the third protective layer (surface modification layer) optimum for the Ag-based light reflection layer (b) will be described.
The conventional Ag-based light reflecting layer is made of ZnS · SiO.₂Has been formed on top. However, ZnS · SiO₂Since Zn and S are contained, the surface is electrochemically active. In addition, SiO₂Microscopically, Si is positively polarized and O is negatively polarized, has good wettability with water and easily retains moisture, and is not suitable for forming an Ag-based light reflecting layer. Therefore, the present inventors have made the above ZnS · SiO between the Ag-based light reflection layer and the second protective layer.₂It was considered to form a third protective layer (surface modified layer) for changing the surface state of a layer having a problem in surface properties due to the relationship with an Ag-based light reflecting layer such as a layer. As characteristics required for the third protective layer, materials and production conditions were examined in consideration of the following points (1) to (4).
(1) Use a non-metal having a small electrochemical action with Ag.
(2) In order not to ionize Ag, adopt a constituent element having an electronegativity smaller than that of Ag.
(3) Use a material with a relatively small binding energy to facilitate physical surface modification.
(4) Use an amorphous material to prevent moisture and impurities from moving through the grain boundaries.
[0028]
As a result of the examination, Si having the following physical properties (i) and (ii) was extracted as an element satisfying the above conditions.
(I) Si is a nonmetal (metalloid), and its electronegativity is 1.8, which is smaller than the electronegativity of Ag 1.9.
(Ii) The Si—Si bond energy is 76 kcal (kilocalorie) / mol, which is smaller than 104 kcal / mol of Si—C bond, 192 kcal / mol of Si—O bond, and 144 kcal / mol of C—C bond.
Next, the present inventors manufactured a DVD + RW compatible optical recording medium having a layer structure as shown in FIG. 1 having various third protective layers based on Si, and the temperature was raised at a rate of 10 ° C./hour. Six heat cycle tests were conducted between the conditions of 95 ° C for 12 hours at 95 ° C and 12 hours for 40 ° C for 95% RH.
The sample medium is a ZnS.SiO2 film having a thickness of 80 nm as a first protective layer on a 0.6 mm thick polycarbonate substrate with guide grooves.₂(20 mol%), 15 nm thick Ga as an optical recording layer₃Ge₃Mn₃Sb₇₁Te₂₀As a second protective layer, ZnS.SiO with a film thickness of 15 nm₂(20 mol%), a film made of the material shown in Table 1 below having a thickness of 5 nm as the third protective layer, and 99.99 wt% Ag having a thickness of 140 nm as the light reflecting layer were sequentially provided by sputtering, and then a resin having a Tg of 130 ° C. After providing the protective layer, the cover substrate was further bonded with an adhesive having a Tg of 135 ° C.
[0029]
[Table 1]

[0030]
In Table 1 above, (1) the molar concentration (%) of the element of the third protective layer, (2) the rank order of the number of chemical bonds in the third protective layer material (type of element-element bond), Bond energy (kcal / mol) of each chemical bond species, (3) Structure of the third protective layer, (4) Average electronegativity of the third protective layer, (5) DVD + RW medium using the third protective layer The defect rate after the heat cycle test is shown. Whether the structure of the third protective layer is crystalline or amorphous was determined to be amorphous if a halo pattern was observed by electron diffraction. In addition, the “defect rate” is a reflectivity having a predetermined reflectivity with respect to the length of the scanned groove when the guide groove is scanned while irradiating a laser beam onto a recordable area of an unrecorded medium. This is the ratio of the length of the part that deviates from the standard value. Further, for example, “7.7E-05” in the defect rate column is “7.7 × 10^-5".
[0031]
The relationship between the defect rate after the heat cycle test of the DVD + RW medium using the third protective layer containing various Si, the Si content of the third protective layer material, and the average electronegativity is shown in FIGS. From FIG. 3 and FIG. 4, it is 1.0E-05 (= 1.0 * 10) which is a defect rate which can ensure reliability.^-5)), It can be seen that the molar concentration of Si in the third protective layer material is preferably 35% or more and an average electronegativity of 2.3 or less.
The average electronegativity referred to here is the average of the electronegativity of the constituent elements according to the ratio of each element, and the average electronegativity of the third protective layer is En (ave). When the molar concentration (%) of the constituent element is mi and the electronegativity of the constituent element is Eni, the following formula is used.
En (ave) = Σmi · Eni
The lower limit of the average electronegativity is not particularly limited in terms of whether or not the effect of the present invention is exhibited, but in practice, the lower limit of the average electronegativity is 1 in the case of simple metals Ti and Ta found in Experiments 15 and 18 in Table 1. .5th place is considered the limit value.
The average electronegativity expresses the polarization state of Ag and the third protective layer. When this polarization is large, moisture (H₂As a result of O) entering the interface, it is considered that the film float of Ag and the third protective layer is promoted.
[0032]
  As described above, the third protective layer needs to contain Si. In order to ensure the reliability of the Ag-based light reflection layer, the third protective layer contains 35 Si.Mole% Or more must be contained. Furthermore, it is effective to increase the molar concentration of Si. However, since the third protective layer has to be considered for matching with the second protective layer as a base from the viewpoint of thermal expansion coefficient, elastic modulus, chemical reactivity, etc., depending on the material of the second protective layer, It is also effective to add C, O, N or the like to Si.
  Even in the third protective layer, which is a thin film compared to other layers, the influence of the optical characteristics on the medium characteristics cannot be ignored. Si is good from the viewpoint of reliability, but has several spectral absorptive powers. If it is too thick, there is no point in providing an Ag-based light reflection layer in order to obtain a high reflectance.
[0033]
The second protective layer is ZnS · SiO₂As the material of the third protective layer in the case of (20 mol%), a material composed of Si, C (carbon) and O (oxygen) in which O is added to Si, SiC or SiC is effective. A mixture with SiOx containing SiC as the main component or a mixture of C (carbon) and SiOx containing SiC as the main component is preferable.
SiC has a characteristic that it has a very high melting point and is thermally stable and dense, so that even if the film thickness is reduced, reaction between sulfur contained in the second dielectric layer and Ag in the reflective layer can be suppressed. Although it has excellent characteristics, it has a drawback that it has high hardness and does not react with Ag, and therefore has poor adhesion.
On the other hand, if a material made of Si, C (carbon) and O (oxygen) is used for the third protective layer as in the present invention, the adhesion is remarkably improved and the corrosion is remarkably reduced.
[0034]
The film thickness of the third protective layer is set to a film thickness that does not significantly affect the high reflectance and high thermal conductivity expected for the Ag-based light reflection layer. Also, flexible response to thermal deformation during recording / erasing expected for the second protective layer, control function of recording sensitivity, control function of initialization state by large aperture LD that crystallizes amorphous recording layer Set so as not to adversely affect
In the study by the present inventors, in consideration of these points, by setting the film thickness DM of the third protective layer in the range of 2 to 9 nm, the recording / erasing signal characteristics can be effectively maintained and the Ag-based light can be maintained. It was found that the reliability of the reflective layer can be ensured.
If it is 2 nm or more, repeatable film formation reproducibility and in-plane uniformity at the time of continuous mass production can be guaranteed, and the function of surface modification will be exhibited. The thickness is preferably 3 to 7 nm, and within this range, the reliability of the Ag-based light reflecting layer can be greatly improved without significantly changing the basic optical design and thermal design of the optical recording medium.
[0035]
Specifically, the jitter after overwriting 1000 times in the DVD + RW format at 14 m / sec is as good as 8% or less. On the other hand, if it exceeds 9 nm, it becomes an intermediate layer as disclosed in JP-A-11-238253 and JP-A-2000-331378 rather than a surface-modified layer, and only modifies the surface. In addition, since the physical property as the intermediate layer becomes a film thickness region that affects the characteristics of the optical recording medium, the optical design and the thermal design need to be significantly changed. It has also been found that internal stress is generated in the third protective layer (surface modified layer) itself, and the third protective layer (surface modified layer) is destroyed by cracks or the like in the heat cycle.
[0036]
Further, when the thickness of the second protective layer is D2, the thickness of the third protective layer is DM, and the thickness of the light reflecting layer is DR, the recording can be performed more effectively if the following conditions are satisfied. It was also found that the erasure signal characteristics can be maintained and the reliability of the Ag-based light reflection layer can be secured.
0.1 ≦ DM / D2 ≦ 0.5, and
0.01 ≦ DM / DR ≦ 0.1
Furthermore, it was also found that if the above conditions are set within the following range, the jitter after 1000 times of overwriting by DVD + RW format at 14 m / sec is as good as 8% or less.
0.15 ≦ DM / D2 ≦ 0.35, and
0.03 ≦ DM / DR ≦ 0.05
[0037]
As a method for producing the third protective layer, sputtering, plasma CVD, plasma treatment, ion plating, optical CVD, and the like can be used. Sputtering widely used in optical recording media is effective. The typical production condition is a pressure of 10^-2-10^-4Pa, sputtering power 0.5 to 5.0 kW / 200 mmφ, and film forming speed 0.5 to 5.0 nm / sec. What is important here is that when the deposition rate of the third protective layer is Rm and the deposition rate of the light reflecting layer is Rr,
0.02 ≦ Rm / Rr ≦ 0.20
0.5 nm / sec ≦ Rm ≦ 5.0 nm / sec
It is to do.
Further, in order to create a film made of Si, C (carbon) and O (oxygen), sputtering using a mixture target of SiC and SiOx, or an SiC target, Ar, and O₂, CO, CO₂Reactive sputtering using a mixed gas with at least one selected from the above is particularly effective.
For example, Ar and CO₂As shown in Table 1, Ar and CO are used.₂The amount of oxygen contained in the third dielectric layer can be controlled by changing the flow rate ratio.
[0038]
This is because the incidence frequency of Ag when forming the Ag-based light reflection layer formed thereon is increased by 5 to 50 times compared to the incidence frequency of atoms constituting the third protective layer on the film. As a result, the outermost surface temperature of the third protective layer is increased, the weakly bonded portion of the third protective layer is eliminated, Ag atoms enter the third protective layer, and when the third protective layer is cooled, This is because the film adhesion force between the Ag-based light reflection film and the third protective layer can be improved by remaining in a wedge-like state.
The film forming speed of the third protective layer is preferably 0.5 to 5.0 nm / sec. When the thickness is 0.5 nm / sec or more, the gas uptake into the third protective layer is reduced, resulting in a dense film. When the thickness is 5 nm / sec or less, the disc-to-disk variation is small, and a thin film of 9 nm or less is formed. It becomes possible to manufacture with good reproducibility.
[0039]
Further, when the sputtering power for the third protective layer is Pm and the sputtering power for the light reflecting layer is Pr,
1.5 × Pm ≦ Pr
By doing so, it is possible to improve the film adhesion between the Ag-based light reflecting film and the third protective layer for the same reason as when the film forming speed condition is satisfied.
In this case, not only the surface temperature of the third protective layer is increased, but also the sputtering power during the formation of the Ag-based light reflection layer is 1.5 times or more, so that the incidence frequency of ions with large energy is also high. Thus, the weakly bonded portion of the third protective layer can be effectively removed, and the adhesion with the Ag-based light reflecting layer can be improved.
The upper limit of the sputtering film forming power Pr of the light reflecting layer is the upper limit of the apparatus specification of the sputtering apparatus. That is, the upper limit power that enables stable sputtering as an apparatus is about 10 kW.
[0040]
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.
[0041]
Example 1
A polycarbonate substrate having a thickness of 0.6 mm having a groove width of 0.25 μm, a groove depth of 27 nm, and a wobble groove period of 4.26 μm and having a thickness of 0.6 mm is injection-molded, and a first protective layer, an optical recording layer, A second protective layer, a third protective layer, and an Ag light reflecting layer having a purity of 99.99% by weight were sequentially laminated by a sputtering method.
For the first protective layer and the second protective layer, ZnS · SiO₂(20 mol%) was used, and the film thicknesses were 80 nm and 14 nm, respectively.
Ga for the optical recording layer₃Ge₃Mn₄Sb₇₀Te₂₀And a thickness of 16 nm.
A Si film having a thickness of 4 nm was used for the third protective layer. A material having an electronegativity of Si of 1.8 and an electronegativity of Ag smaller than 1.9 was selected.
The Ag light reflection layer had a thickness of 140 nm.
The film formation rates of the first protective layer, the optical recording layer, the second protective layer, the third protective layer, and the Ag light reflecting layer were 9 nm / sec, 5.6 nm / sec, 4.5 nm / sec, and 1.5 nm / sec, respectively. sec, 32 nm / sec, and the film-forming sputtering power was 4 kW, 0.4 kW, 1.5 kW, 1.5 kW, and 3.5 kW, respectively.
As a result, polycarbonate substrate / ZnS · SiO₂(80 nm) / Ga₃Ge₃Mn₄Sb₇₀Te₂₀(16nm) / ZnS · SiO₂A stacked structure of (14 nm) / Si (4 nm) /99.99 wt% Ag (140 nm) was formed.
Next, an ultraviolet curable resin having a room temperature viscosity of 120 cps and a glass transition temperature after curing of 149 ° C. is spin-coated on the Ag light reflecting layer to form a resin protective layer, and a single disk disk of a phase change optical recording medium is formed. Created.
Next, the bonded substrate made of polycarbonate was bonded with an ultraviolet curable adhesive having a room temperature viscosity of 580 cps and a glass transition temperature of 135 ° C. after curing to obtain an optical recording medium having a DVD type configuration as shown in FIG. .
[0042]
Next, with an initialization device having a large aperture LD (laser diode with a beam diameter of 200 × 1 μm), the linear velocity is 3.5 m / sec, the power (LD power) is 850 mW, the feed is 120 μm, from the inner periphery to the outer periphery, The entire surface was crystallized at a constant linear velocity.
Subsequently, optical recording was performed on the obtained phase-change optical recording medium in a DVD-ROM reproducible format at a recording linear velocity of 16.75 m / sec, a wavelength of 650 nm, NA of 0.65, and a recording power of 14.5 mW.
As a result, Data to Clock Jitter (data to clock jitter) after recording 1000 times of direct overwrite (DOW) was as good as 7.5%. Further, the signal characteristics were good with a reflectivity of 20% and a modulation factor of 63%, and the original high light reflectivity and high heat conductivity of Ag could be used efficiently.
Further, this optical recording medium was subjected to six heat cycle tests under the conditions of 25 ° C. 95% RH 12 hours—40 ° C. 95% RH 12 hours at a temperature increase / decrease rate of 10 ° C./hour. No change was observed with a modulation degree of 63% and a tilt of 58 ° on the outer periphery of 0.4 °. Further, no increase in the defect rate was observed.
[0043]
Examples 2-13
A polycarbonate substrate having a thickness of 0.6 mm having a groove width of 0.25 μm, a groove depth of 27 nm, and a wobble groove period of 4.26 μm and having a thickness of 0.6 mm is injection-molded, and a first protective layer, an optical recording layer, A second protective layer, a third protective layer, and an Ag light reflecting layer having a purity of 99.99% by weight were sequentially laminated by a sputtering method.
For the first protective layer and the second protective layer, ZnS · SiO₂(20 mol%) and Ga for the optical recording layer.₃Ge₃Mn₄Sb₇₀Te₂₀The materials shown in Table 2 below were used for the third protective layer. Table 2 shows the film thickness and manufacturing conditions of each layer at this time.
Next, an environmental protection layer is formed on the Ag light reflection layer by spin-coating an ultraviolet curable resin having a room temperature viscosity of 120 cps and a glass transition temperature of 149 ° C. after curing to form a single disk of a phase change optical recording medium. Created.
Next, the bonded substrate made of polycarbonate was bonded with an ultraviolet curable adhesive having a room temperature viscosity of 580 cps and a glass transition temperature of 135 ° C. after curing to obtain an optical recording medium having a DVD type configuration as shown in FIG. .
[0044]
Next, with an initialization device having a large-diameter LD (laser diode with a beam diameter of 200 × 1 μm), the linear velocity is 3.5 m / sec, the power (LD power) is 850 mW, the feed is 120 μm, and the line is moved from the inner periphery toward the outer periphery. The entire surface was crystallized at a constant speed.
Next, optical recording was performed on the obtained phase change optical recording medium in a format capable of reproducing DVD-ROM at a recording linear velocity of 16.75 m / sec, a wavelength of 650 nm, NA of 0.65, and a recording power of 14.5 mW.
As a result, when the thickness of the third protective layer was 2 to 9 nm, the jitter after 1000 times of DOW was as good as 9% or less. Further, at 3 to 7 nm, the jitter after 1000 times of DOW was 8% or less, which was better. Further, the signal characteristics were good with a reflectivity of 20% and a modulation factor of 63%, and the original high light reflectivity and high heat conductivity of Ag could be used efficiently.
Further, this optical recording medium was subjected to a storage test of 80 ° C. and 85% RH for 500 hours and six heat cycle tests of 25 ° C. and 95% RH for 12 hours to 40 ° C. and 95% RH for 12 hours at a temperature rising / lowering speed of 10 ° C./hour As a result, as shown in Table 2 below, an increase in defect rate and a significant increase in errors were not recognized.
[0045]
Comparative Examples 1-7
An optical recording medium was prepared in the same manner as in Examples 2 to 13 except that the material and film thickness of the third protective layer were changed to those shown in Table 2 below, and the same as in Examples 2 to 13 The test was conducted. The results are shown in Table 2.
As can be seen from Table 2, Comparative Example 1 is an example in which the third protective layer was not provided, and Comparative Examples 2 to 7 were the materials for the third protective layer according to the requirements of the present invention (Si atoms of 35 mol% or more). The film thickness is 1 nm or 10 nm, which is outside the range of the present invention of 2 to 9 nm. Therefore, in all cases, there is a problem with at least one of the jitter after 1000 times of DOW, the jitter after storage for 500 hours, and the jitter after the cycle, and only NG was obtained as a comprehensive judgment.
[0046]
[Table 2]

[0047]
Examples 14-18, Comparative Examples 8-10
A 0.6 mm thick polycarbonate substrate having a guide groove with a groove width of 0.25 μm and a groove depth of 27 nm is injection-molded, and a first protective layer, a recording layer, a second protective layer, and a third protective layer are formed on this substrate. And an Ag light reflecting layer having a purity of 99.99% by weight were sequentially laminated by a sputtering method.
For the first protective layer and the second protective layer, ZnS · SiO₂(20 mol%) was used, and the film thicknesses were 80 nm and 14 nm, respectively.
The recording layer has Ge_2.0Ag_0.5In_5.0Sb_68.5Te_24.0And a thickness of 16 nm.
As the third protective layer, a film having a thickness of 4 nm was formed by sputtering using a SiC target and a mixed gas having a flow rate ratio shown in Table 3 under the conditions of a pressure of 0.5 Pa and a power of 1 kW.
The Ag light reflection layer had a thickness of 140 nm.
As a result, polycarbonate substrate / ZnS · SiO₂(80 nm) / Ge_2.0Ag_0.5In_5.0Sb_68.5Te_24.0(16nm) / ZnS · SiO₂A stacked structure of (14 nm) / SiC (4 nm) / Ag (140 nm) was formed.
Next, an ultraviolet curable resin having a room temperature viscosity of 120 cps and a cured glass transition temperature of 149 ° C. is spin-coated on the Ag light reflecting layer to form an overcoat layer, and a single-disc disk of a phase change optical recording medium is formed. Produced.
Furthermore, a polycarbonate cover substrate was bonded together with an ultraviolet curable adhesive to obtain an optical recording medium having the configuration shown in FIG.
[0048]
Next, with an initialization device having a large aperture LD (beam diameter 200 × 1 μm), the linear velocity is constant from the inner circumference to the outer circumference at a linear velocity of 3.0 m / sec, power (LD power) of 850 mW, and feed of 100 μm. The entire surface was crystallized.
Subsequently, optical recording was performed on the obtained phase-change optical recording medium in a DVD-ROM reproducible format at a recording linear velocity of 8.5 m / sec, a wavelength of 650 nm, NA of 0.65, and a recording power of 14 mW.
As a result, as shown in Table 3, the number of times Data to Clock Jitter after DOW recording was 9% or more was the case where the amount of oxygen contained in the third dielectric layer was 20% or less. When the oxygen content exceeded 20%, cracks in the third dielectric and peeling of the reflective layer occurred due to overwriting. In addition, when the amount of oxygen is zero, the error increase rate after the storage test at 80 ° C. and 85% for 300 hours [(error after storage−initial error) / initial error] greatly exceeds 10%, so some data cannot be read. However, when the oxygen amount was 1 atomic% or more, the increase rate was 10% or less, and it was possible to regenerate without problems even after the storage test.
Further, when the Auger depth profile (Auger electron spectroscopic depth direction analysis) of the optical recording medium of Example 17 was measured, the result shown in FIG. 5 was obtained, and C (carbon) in excess of Si was taken into the film. It was confirmed that
The Auger depth profile is a method of quantifying the composition ratio by irradiating high energy (1 to 5 keV) electrons and spectroscopically analyzing Auger electrons having energy inherent to the substance emitted from the substance surface.
[0049]
[Table 3]

[0050]
【The invention's effect】
According to the present invention, by utilizing the high reflectivity and high thermal conductivity of the Ag-based light reflection layer, Ag ionization and Ag void generation are suppressed without greatly affecting optical design and thermal design, and Ag light It is possible to provide an optical recording medium with improved adhesion between the reflective layer and the third protective layer, which is highly reliable even at high temperature and high humidity storage, and a method for manufacturing the same.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a DVD type optical recording medium according to the present invention.
FIG. 2 is a diagram showing an example of a CD type optical recording medium according to the present invention.
FIG. 3 is a graph showing the dependency of the heat cycle reliability of a DVD + RW medium on the Si content of the third protective layer material.
FIG. 4 is a graph showing the dependence of the heat cycle reliability of the DVD + RW medium on the average electronegativity of the third protective layer material.
5 is a graph showing the results of measuring the Auger depth profile of the optical recording medium of Example 17. FIG.
[Explanation of symbols]
1 Substrate
2 First protective layer
3 Optical recording layer
4 Second protective layer
5 Third protective layer
6 Light reflection layer
7 Resin protective layer
8 Adhesive layer
9 Cover substrate
10 Print layer

Claims (18)

On the substrate, at least a first protective layer, an optical recording layer, a second protective layer , a third protective layer, and a light reflecting layer made of a material containing 95% by weight or more of Ag are disposed in this order, and further on the light reflecting layer. In the optical recording medium having the resin protective layer and / or the adhesive layer, the second protective layer is made of a substance containing ZnS and SiO _2, and the thickness of the second protective layer is in the range of 5 to 45 nm. 3 The protective layer is made of a material composed of Si, C, and O (containing 35 mol% or more of Si atoms and 1 to 20 atom% of O atoms), SiC (containing 35 mol% or more of Si atoms), and Si only. made from any optical recording medium having a thickness DM of the third protective layer, characterized in that the range of 2～9Nm.   2. The optical recording medium according to claim 1, wherein the film thickness DM of the third protective layer is in the range of 3 to 7 nm. When the thickness of the second protective layer is D2, the thickness of the third protective layer is DM, and the thickness of the light reflecting layer is DR,
0.1 ≦ DM / D2 ≦ 0.5 and 0.01 ≦ DM / DR ≦ 0.1
The optical recording medium according to claim 1 or 2, wherein the at. 4. The optical recording medium according to claim 3, wherein 0.15 ≦ DM / D2 ≦ 0.35 and 0.03 ≦ DM / DR ≦ 0.05. When the third protective layer has an average electronegativity of En (ave), the molar concentration (%) of the constituent element is mi, and the electronegativity of the constituent element is En,
En (ave) = (Σmi × Eni) /100≦2.3
The optical recording medium according to any one of claims 1-4, characterized in that it consists of an amorphous material is. The glass transition temperature of the resin protective layer and / or adhesive layer on the optical reflective layer, an optical recording medium according to any one of claims 1 to 5, characterized in that a 90 to 180 ° C.. The optical recording medium according to claim 6 , wherein the glass transition temperature is 100 to 165 ° C. And a light reflecting layer on the resin protective layer adhesive layer, the difference in the glass transition temperature of both layers, the optical recording medium according to any one of claims 1 to 7, characterized in that at 50 ° C. or less . The optical recording medium according to claim 8 , wherein the difference in glass transition temperature is 30 ° C. or less. The light reflecting layer is made of a material in which at least one element selected from Al, Bi, Ca, Cu, Cd, Fe, Mn, Mg, Ni, Pd, Pb, Sb, Zn, and Nd is added to Ag. the optical recording medium according to any one of claims 1 to 9, characterized in that. The optical recording medium according to claim 10 , wherein the elements added to Ag are Cu and Nd. The guide groove formed in the substrate has a width of 0.10 to 0.40 μm and a depth of 15 to 45 nm (a rewritable optical recording medium compatible with DVD-ROM). The optical recording medium according to any one of 11 . 13. The optical recording medium according to claim 12 , wherein the guide groove has a width of 0.15 to 0.35 [mu] m and a depth of 20 to 40 nm. Light according to any one of claims 1 to 13, the width of the guide groove formed on the substrate 0.25～0.65Myuemu, depth, characterized in that a 20 to 50 nm (CD-RW media) recoding media. The optical recording medium according to claim 14 , wherein the guide groove has a width of 0.30 to 0.60 μm and a depth of 25 to 45 nm. When the deposition rate of the third protective layer is Rm and the deposition rate of the light reflecting layer is Rr, both layers are
0.02 ≦ Rm / Rr ≦ 0.20
0.5 nm / sec ≦ Rm ≦ 5.0 nm / sec
The method of manufacturing an optical recording medium according to any one of claims 1 to 15, characterized in that the film under the condition that. When the sputtering deposition power of the third protective layer is Pm and the sputtering deposition power of the light reflecting layer is Pr, both layers are
1.5 × Pm ≦ Pr
The method of manufacturing an optical recording medium according to any one of claims 1 to 15, characterized in that the film under the condition that. Third protective layer, when formed of Si and C and consisting of O material (Si atoms and containing 35 mol% or more containing O atoms 1-20 atomic%), the third protective layer, SiC target, and , Ar _and, O 2, CO, optical recording according to any one of claims 1 to 15, characterized in that the film by reactive sputtering using a mixed gas of at least one selected from CO ₂ A method for producing a medium.

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