JP3878337B2 - Method for producing non-initialization type phase change optical recording medium - Google Patents

Description

【００８４】
次に、これらサンプルＡ〜Ｆ及び比較用サンプルについて、作製直後における相変化記録膜５の非晶質状態の安定性を、図６に示す光ディスクドライブ装置を用いて、以下に示す方法により評価した。なお、図６は、本発明の実施例において用いられる光ディスクドライブ装置を概略的に示す図である。
【００８５】
図６に示すように、相変化光記録媒体（ディスク）１-4は、スピンドルモータ３２の回転軸に保持される。ディスク１-4は、スピンドルモータ３２の回転数を制御することにより、所定の回転数で回転される。本実施例においては、ＤＶＤ−ＲＡＭを想定して、ディスク１-4と光学ヘッド３３との相対速度が１２ｍ／ｓで一定となるように、ディスク１-4の回転軸と光学ヘッド３３との間の距離に応じてディスク１-4の回転速度を変化させる、いわゆる線速度一定方式を採用した。
【００８６】
入力装置３６から入力される信号は、変調回路３５において、例えばＤＶＤ−ＲＡＭを想定した場合は８／１６変調で、１または０の信号へとデジタル化される。変調回路３５からのデジタル信号はレーザドライバ３７へと送られ、光学ヘッド３３から出射されるレーザ光のＯＮ／ＯＦＦを制御する。これにより、ディスク１-4上へのデータの書込みが行われる。
【００８７】
本実施例においてディスク１-4は相変化光記録媒体であるので、ディスク１-4への情報の記録、ディスク１-4に記録された情報の消去、及びディスク１-4に記録された情報の再生は、全てレーザ光等を照射することにより行われる。
【００８８】
図７に、本発明の実施例に係る相変化光記録媒体における、情報の記録・消去・再生に必要なレーザ光のパワーをグラフにして示す。なお、図中、横軸は時間を示し、縦軸はレーザ光のパワーを示している。
【００８９】
図７に示すように、情報の記録を行う場合は、レーザ光のパワーをＰ_w まで高めて相変化記録膜を溶融・急冷することにより非晶質状態とする。また、記録された情報の消去を行う場合は、レーザ光のパワーをＰ_e 程度として、相変化記録膜をその結晶化温度以上、融点未満まで加熱することにより結晶化させる。なお、図中、Ｐ_r は記録された情報の再生を行う場合に必要なレーザ光のパワーである。ディスク１-4に情報を書込むと、その部分は非晶質となる。非晶質部分と結晶質部分とでは反射率が異なるので、ディスク１-4上を一定かつ弱いパワーのレーザ光を用いて走査することにより、記録された信号を反射光量の差として検出することができる。
【００９０】
ディスク１-4にパワーＰ_r のレーザ光を照射することにより得られる再生信号は、光学ヘッド３３に接続されたプリアンプ３８で増幅される。増幅された再生信号は、次に２値化回路３９において、アナログ信号からデジタル信号へとデジタル化される。デジタル化された再生信号は、さらに復調回路４０において、８／１６変調に基づいて復調され、アナログ信号として出力装置４１へと出力される。
【００９１】
なお、図７において、制御系４３は、レーザドライバ３７を介して光学ヘッド３３から出射されるレーザ光強度を制御したり、例えば、リニアモータ駆動制御系４６を介してリニアモータ３４を駆動することにより光学ヘッド３３を所望の位置に制御するのに用いられる。また、制御系４３は、フォーカス駆動制御系４４やトラック駆動制御系４５を介して、光学ヘッド３３に設けられた対物レンズアクチュエータを駆動することにより、ディスク１-4の面振れやトラックの偏心に追従するように対物レンズの位置を制御するのに用いられる。
【００９２】
このように構成される光ディスクドライバ装置３０を用いて、サンプルＡ〜Ｆ及び比較用サンプルについて、以下に示す方法により製造直後における相変化記録膜の非晶質状態の安定性について評価を行った。すなわち、ディスク１-4（サンプルＡ〜Ｆ及び比較用サンプル）に初期結晶化を行うことなく、上記光ディスクドライバ装置３０により図７に示すパワーＰ_e の消去用のレーザ光及びパワーＰ_w の記録用のレーザ光を照射した。すなわち、オーバーライト記録を行った。
【００９３】
なお、信号の記録は、ＤＶＤ−ＲＡＭを想定して、線速度が１２ｍ／ｓで一定となるようにスピンドルモータ３２の回転数を制御し、８／１６変調、デューティ５０％として、周波数１４．２ＭＨｚのレーザ光を照射してマークエッジ記録を行い、相変化記録膜に最短マーク長である３Ｔを形成することにより行った。また、パワーＰ_w は１４ｍＷとし、パワーＰ_e は５ｍＷとした。
【００９４】
また、作製直後における相変化記録膜は非晶質状態にあり、かつサンプルＡ〜Ｆ及び比較用サンプルは全てＬｔｏＨメディアであるため、作製直後における相変化記録膜の反射率は０．１８程度と十分に高かった。したがって、光ディスクドライブ装置３０において、サーボ制御可能であり、また、試験中にサーボ制御不能となることはなかった。
【００９５】
次に、情報を記録したディスク１-4について記録の再生を行い、スペクトラム・アナライザを用いてＣ／Ｎ値を測定した。なお、Ｃ／Ｎ値が低すぎる場合は、パワーＰ_e の消去用のレーザ光を照射することによる相変化記録膜の結晶化が不完全であったと判断することができる。したがって、この場合は、オーバーライト記録を再度行った。
【００９６】
十分に大きなＣ／Ｎ値が得られるまで、相変化記録膜の同じ領域に対して、上記オーバーライト記録とＣ／Ｎ値の測定とを繰り返し行い、その繰返し回数により、作製直後における相変化記録膜の非晶質状態の安定性を評価した。以下にその結果を示す。
【００９７】
まず、比較用サンプルについて上記測定を行ったところ、１回目のオーバーライト記録直後では、１４．２ＭＨｚのスペクトルは殆ど観測されなかった。オーバーライト記録とＣ／Ｎ値の測定とを繰り返し行ったところ、Ｃ／Ｎ値が４０ｄＢに達するのに６回のオーバーライト記録を必要とした。また、Ｃ／Ｎ値が５２ｄＢに達するのに１５回のオーバーライト記録を必要とした。以上から、従来の方法により製造した比較用サンプルは、作製直後において、相変化記録膜の非晶質状態が過剰に安定であることが確認された。
【００９８】
次に、サンプルＡについて上記測定を行ったところ、１回目のオーバーライト記録で、４０ｄＢを超えるＣ／Ｎ値を得ることができた。また、オーバーライト記録を３回繰返すことにより、Ｃ／Ｎ値を５２ｄＢとすることができた。また、サンプルＢについて上記測定を行ったところ、１回目のオーバーライト記録で、Ｃ／Ｎ値を５０ｄＢとすることができた。また、オーバーライト記録を２回繰返すことにより、Ｃ／Ｎ値を５２ｄＢとすることができた。
【００９９】
以上の結果から、ＺｎＳ／ＳｉＯ₂ 膜４-1に残留応力を導入することにより、製造直後における記録膜を非晶質状態から結晶質状態へと容易に変化させることが可能となることが確認された。また、相変化記録膜の成膜時に、スパッタリングガス圧を高めることにより、記録膜原料の急冷度を低減し、作製直後における相変化記録膜の非晶質状態の過剰な安定性を低減可能であることが確認された。
【０１００】
次に、サンプルＣについて上記測定を行ったところ、１回目のオーバーライト記録でＣ／Ｎ値を４０ｄＢとすることができた。また、オーバーライト記録を３回繰返すことにより、Ｃ／Ｎ値を５２ｄＢとすることができた。また、サンプルＤについて上記測定を行ったところ、１回目のオーバーライト記録の直後にＣ／Ｎ値は５０ｄＢに達し、２回目のオーバーライト記録でＣ／Ｎ値を５２ｄＢとすることができた。以上の結果から、残留応力を導入する層がＺｎＳ／ＳｉＯ₂ 膜４-1及びＺｎＳ／ＳｉＯ₂ 膜４-2のいずれであっても同様の効果が得られることが確認された。
【０１０１】
次に、サンプルＥ，Ｆについて上記測定を行ったところ、ともに１回目のオーバーライト記録でＣ／Ｎ値を５２ｄＢ以上とすることができた。以上の結果から、ＺｎＳ／ＳｉＯ₂ 膜４-1及びＺｎＳ／ＳｉＯ₂ 膜４-2の双方に残留応力を導入することにより、一方のみに残留応力を導入した場合に比べて、製造直後において非晶質状態にある記録膜をさらに容易に結晶質状態へと変化させることが可能となることが確認された。
【０１０２】
（実施例４）
図５に示すスパッタ装置を用いて図１に示す相変化光記録媒体１-1を作製した。なお、本例においてターゲット１３-4の材料としては、ＡｌＭｏの代わりにＧｅが用いられる。
【０１０３】
相変化光記録媒体１-1を作製するに当たり、まず、サンプルＡと同様にして、ディスク２上にＡｕ膜３を成膜した。
Ａｕ膜３を成膜した後、バルブ１０-1を閉じ、チャンバー２１内に残留するＡｒガスとＡｕ原子とを真空ターボポンプ１２を用いて排気した。排気終了後、再度バルブ１０-1を開放して、マスフローコントローラで流量制御しつつＡｒガスをチャンバー２１内に導入し、チャンバー内のＡｒガス圧を５×１０^-3ｔｏｒｒに制御した。
【０１０４】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に接続して、電極１４-2に６００ＷのＲＦ電力を供給した。以上のようにして、電極１４-2上に配置されたＺｎＳ／ＳｉＯ₂ ターゲット１３-2のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、ＺｎＳ／ＳｉＯ₂ ターゲット１３-2の上方に配置されたシャッタ１５-2を開放した。８分３０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に絶縁し、さらにシャッタ１５-2を閉じた。以上のようにして、Ａｕ膜３上に誘電体膜４-1として、厚さ８５０オングストロームのＺｎＳ／ＳｉＯ₂ 膜４-1を成膜した。
【０１０５】
ＺｎＳ／ＳｉＯ₂ 膜４-1を成膜した後、バルブ１０-1を閉じ、チャンバー２１内に残留するＡｒガスとＺｎＳ／ＳｉＯ₂ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-3を開放して、マスフローコントローラで流量制御しつつＡｒガスとＮ₂ ガスとの混合ガスをチャンバー２１内に導入し、チャンバー内の混合ガス圧を５×１０^-3ｔｏｒｒに制御した。なお、ＡｒガスとＮ₂ ガスとの流量比は１：１である。
【０１０６】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-4とを電気的に接続して、電極１４-4に２５０ＷのＲＦ電力を供給した。以上のようにして、電極１４-4上に配置されたＧｅターゲット１３-4のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、Ｇｅターゲット１３-4の上方に配置されたシャッタ１５-4を開放した。２０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-4とを電気的に絶縁し、さらにシャッタ１５-4を閉じた。以上のようにして、ＺｎＳ／ＳｉＯ₂ 膜４-1上に結晶化誘起層８-1として、厚さ５０オングストロームのＧｅＮ膜８-1を成膜した。
【０１０７】
ＧｅＮ膜８-1を成膜した後、バルブ１０-3を閉じ、チャンバー２１内に残留するＡｒガスとＮ₂ ガスとＺｎＳ／ＳｉＯ₂ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-2を開放して、マスフローコントローラで流量制御しつつＫｒガスをチャンバー２１内に導入し、チャンバー内のＫｒガス圧を５×１０^-2ｔｏｒｒに制御した。
【０１０８】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-3とを電気的に接続して、電極１４-3に２００ＷのＲＦ電力を供給した。以上のようにして、電極１４-3上に配置されたＧｅ₂ Ｓｂ₂ Ｔｅ₅ ターゲット１３-3のＫｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ ターゲット１３-3の上方に配置されたシャッタ１５-3を開放した。４０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-3とを電気的に絶縁し、さらにシャッタ１５-3を閉じた。以上のようにして、ＧｅＮ膜８-1上に相変化記録膜５として、厚さ１００オングストロームのＧｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５を成膜した。
【０１０９】
Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５を成膜した後、バルブ１０-2を閉じ、チャンバー２１内に残留するＫｒガスとＧｅ₂ Ｓｂ₂ Ｔｅ₅ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-1を開放して、マスフローコントローラで流量制御しつつＡｒガスをチャンバー２１内に導入し、チャンバー内のＡｒガス圧を５×１０^-3ｔｏｒｒに制御した。
【０１１０】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に接続して、電極１４-2に６００ＷのＲＦ電力を供給した。以上のようにして、電極１４-2上に配置されたＺｎＳ／ＳｉＯ₂ ターゲット１３-2のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、ＺｎＳ／ＳｉＯ₂ ターゲット１３-2の上方に配置されたシャッタ１５-2を開放した。３分経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に絶縁し、さらにシャッタ１５-2を閉じた。以上のようにして、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５上に誘電体膜４-2として、厚さ３００オングストロームのＺｎＳ／ＳｉＯ₂ 膜４-2を成膜した。
【０１１１】
ＺｎＳ／ＳｉＯ₂ 膜４-2を成膜した後、バルブ１０-1を閉じ、チャンバー２１内に残留するＡｒガスとＺｎＳ／ＳｉＯ₂ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、再度バルブ１０-1を開放して、マスフローコントローラで流量制御しつつＡｒガスをチャンバー２１内に導入し、チャンバー内のＡｒガス圧を５×１０^-3ｔｏｒｒに制御した。
【０１１２】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-1とを電気的に接続して、電極１４-1に１５０ＷのＲＦ電力を供給した。以上のようにして、電極１４-1上に配置されたＡｕターゲット１３-1のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、Ａｕターゲット１３-1の上方に配置されたシャッタ１５-1を開放した。２分３０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-1とを電気的に絶縁し、さらにシャッタ１５-1を閉じた。以上のようにして、ＺｎＳ／ＳｉＯ₂ 膜４-2上にＡｕ金属反射層６として、厚さ１０００オングストロームのＡｕ膜６を成膜した。
【０１１３】
上述した方法により、ディスク２上にそれぞれの膜を成膜した後、ディスク２をチャンバー２１から取り出した。このディスク２のＡｕ膜６上に、スピンコータを用いてＵＶ硬化樹脂をスピンコートし、ＵＶ光を照射することにより、Ａｕ膜６上に保護膜７を形成した。
【０１１４】
以上のようにして、ディスク２上に、厚さ１００オングストロームのＡｕ膜３、厚さ８５０オングストロームのＺｎＳ／ＳｉＯ₂ 膜４-1、厚さ５０オングストロームのＧｅＮ膜８-1、厚さ１００オングストロームのＧｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５、厚さ３００オングストロームのＺｎＳ／ＳｉＯ₂ 膜４-2、厚さ１０００オングストロームのＡｕ膜６、及び厚さ８μｍの保護膜７を順次積層して相変化光記録媒体１-1を作製した。この相変化光記録媒体１-1をサンプルＧとする。
【０１１５】
また、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の成膜時のＫｒガス圧を５×１０^-1ｔｏｒｒに制御したこと以外はサンプルＧと同様にして相変化光記録媒体１-1を作製した。すなわち、サンプルＧに比べ、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の成膜時における急冷度をさらに低減して相変化光記録媒体１-1を作製した。この相変化光記録媒体１-1をサンプルＨとする。
【０１１６】
（実施例５）
図５に示すスパッタ装置を用いて図２に示す相変化光記録媒体１-2を作製した。
【０１１７】
相変化光記録媒体１-2を作製するに当たり、まず、サンプルＧと同様にして、ディスク２上にＡｕ膜３及びＺｎＳ／ＳｉＯ₂ 膜４-1を順次成膜した。
ＺｎＳ／ＳｉＯ₂ 膜４-1を成膜した後、バルブ１０-1を閉じ、チャンバー２１内に残留するＡｒガスとＺｎＳ／ＳｉＯ₂ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-2を開放して、マスフローコントローラで流量制御しつつＫｒガスをチャンバー２１内に導入し、チャンバー内のＫｒガス圧を５×１０^-2ｔｏｒｒに制御した。
【０１１８】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-3とを電気的に接続して、電極１４-3に２００ＷのＲＦ電力を供給した。以上のようにして、電極１４-3上に配置されたＧｅ₂ Ｓｂ₂ Ｔｅ₅ ターゲット１３-3のＫｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ ターゲット１３-3の上方に配置されたシャッタ１５-3を開放した。４０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-3とを電気的に絶縁し、さらにシャッタ１５-3を閉じた。以上のようにして、ＺｎＳ／ＳｉＯ₂ 膜４-1上に相変化記録膜５として、厚さ１００オングストロームのＧｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５を成膜した。
【０１１９】
Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５を成膜した後、バルブ１０-2を閉じ、チャンバー２１内に残留するＫｒガスとＧｅ₂ Ｓｂ₂ Ｔｅ₅ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-3を開放して、マスフローコントローラで流量制御しつつＡｒガスとＮ₂ ガスとの混合ガスをチャンバー２１内に導入し、チャンバー内の混合ガス圧を５×１０^-3ｔｏｒｒに制御した。なお、ＡｒガスとＮ₂ ガスとの流量比は１：１である。
【０１２０】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-4とを電気的に接続して、電極１４-4に２５０ＷのＲＦ電力を供給した。以上のようにして、電極１４-4上に配置されたＧｅターゲット１３-4のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、Ｇｅターゲット１３-4の上方に配置されたシャッタ１５-4を開放した。２０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-4とを電気的に絶縁し、さらにシャッタ１５-4を閉じた。以上のようにして、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５上に結晶化誘起層８-1として、厚さ５０オングストロームのＧｅＮ膜８-2を成膜した。
【０１２１】
ＧｅＮ膜８-2を成膜した後、バルブ１０-3を閉じ、チャンバー２１内に残留するＡｒガスとＮ₂ ガスとＺｎＳ／ＳｉＯ₂ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-1を開放して、マスフローコントローラで流量制御しつつＡｒガスをチャンバー２１内に導入し、チャンバー内のＡｒガス圧を５×１０^-3ｔｏｒｒに制御した。
【０１２２】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に接続して、電極１４-2に６００ＷのＲＦ電力を供給した。以上のようにして、電極１４-2上に配置されたＺｎＳ／ＳｉＯ₂ ターゲット１３-2のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、ＺｎＳ／ＳｉＯ₂ ターゲット１３-2の上方に配置されたシャッタ１５-2を開放した。３分経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に絶縁し、さらにシャッタ１５-2を閉じた。以上のようにして、ＧｅＮ膜８-2上に誘電体膜４-2として、厚さ３００オングストロームのＺｎＳ／ＳｉＯ₂ 膜４-2を成膜した。
【０１２３】
さらに、サンプルＧと同様にして、ＺｎＳ／ＳｉＯ₂ 膜４-2上に、Ａｕ膜６及び保護膜７を順次積層して相変化光記録媒体１-2を作製した。この相変化光記録媒体１-2をサンプルＩとする。
【０１２４】
また、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の成膜時のＫｒガス圧を５×１０^-1ｔｏｒｒに制御したこと以外はサンプルＩと同様にして相変化光記録媒体１-2を作製した。すなわち、サンプルＩに比べ、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の成膜時における急冷度をさらに低減して相変化光記録媒体１-2を作製した。この相変化光記録媒体１-2をサンプルＪとする。
【０１２５】
（実施例６）
図５に示すスパッタ装置を用いて図３に示す相変化光記録媒体１-3を作製した。
【０１２６】
相変化光記録媒体１-3を作製するに当たり、まず、サンプルＧと同様にして、ディスク２上に、Ａｕ膜３、ＺｎＳ／ＳｉＯ₂ 膜４-1、ＧｅＮ膜８-1、及びＫｒガス圧を５×１０^-2ｔｏｒｒとしてＧｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５を順次成膜した。
【０１２７】
Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５を成膜した後、バルブ１０-2を閉じ、チャンバー２１内に残留するＫｒガスとＧｅ₂ Ｓｂ₂ Ｔｅ₅ 分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-3を開放して、マスフローコントローラで流量制御しつつＡｒガスとＮ₂ ガスとの混合ガスをチャンバー２１内に導入し、チャンバー内の混合ガス圧を５×１０^-3ｔｏｒｒに制御した。なお、ＡｒガスとＮ₂ ガスとの流量比は１：１である。
【０１２８】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-4とを電気的に接続して、電極１４-4に２５０ＷのＲＦ電力を供給した。以上のようにして、電極１４-4上に配置されたＧｅターゲット１３-4のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、Ｇｅターゲット１３-4の上方に配置されたシャッタ１５-4を開放した。２０秒経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-4とを電気的に絶縁し、さらにシャッタ１５-4を閉じた。以上のようにして、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５上に結晶化誘起層８-1として、厚さ５０オングストロームのＧｅＮ膜８-1を成膜した。
【０１２９】
ＧｅＮ膜８-1を成膜した後、バルブ１０-3を閉じ、チャンバー２１内に残留するＡｒガスとＮ₂ ガスとＧｅ分子とを真空ターボポンプ１２を用いて排気した。排気終了後、バルブ１０-1を開放して、マスフローコントローラで流量制御しつつＡｒガスをチャンバー２１内に導入し、チャンバー内のＡｒガス圧を５×１０^-3ｔｏｒｒに制御した。
【０１３０】
次に、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に接続して、電極１４-2に６００ＷのＲＦ電力を供給した。以上のようにして、電極１４-2上に配置されたＺｎＳ／ＳｉＯ₂ ターゲット１３-2のＡｒガスによるスパッタリングを開始した。約１分間プリスパッタした後、ＺｎＳ／ＳｉＯ₂ ターゲット１３-2の上方に配置されたシャッタ１５-2を開放した。３分経過後、切替スイッチ１７を用いてＲＦ電源１６と電極１４-2とを電気的に絶縁し、さらにシャッタ１５-2を閉じた。以上のようにして、ＧｅＮ膜８-1上に誘電体膜４-2として、厚さ３００オングストロームのＺｎＳ／ＳｉＯ₂ 膜４-2を成膜した。
【０１３１】
さらに、サンプルＧと同様にして、ＺｎＳ／ＳｉＯ₂ 膜４-2上に、Ａｕ膜６及び保護膜７を順次積層して相変化光記録媒体１-3を作製した。この相変化光記録媒体１-3をサンプルＫとする。
【０１３２】
また、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の成膜時のＫｒガス圧を５×１０^-1ｔｏｒｒに制御したこと以外はサンプルＫと同様にして相変化光記録媒体１-3を作製した。すなわち、サンプルＫに比べ、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の成膜時における急冷度をさらに低減して相変化光記録媒体１-3を作製した。この相変化光記録媒体１-3をサンプルＬとする。
【０１３３】
以上のようにして作製したサンプルＧ〜Ｌ及び比較用サンプルについて、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５の製造条件の違いと、ＧｅＮ膜８-1，８-2の有無とを下記表２に纏める。
【０１３４】
【表２】

【０１３５】
次に、これらサンプルＧ〜Ｌについて、サンプルＡ〜Ｆ及び比較用サンプルに関して実施したのと同様の試験を行った。その結果、サンプルＧについては、１回目のオーバーライト記録で４５ｄＢを超えるＣ／Ｎ値を得ることができた。また、オーバーライト記録を３回繰返すことにより、Ｃ／Ｎ値を５２ｄＢとすることができた。サンプルＨについては、１回目のオーバーライト記録でＣ／Ｎ値を５１ｄＢとすることができた。また、オーバーライト記録を２回繰返すことにより、Ｃ／Ｎ値を５２ｄＢとすることができた。
【０１３６】
以上の結果から、Ｇｅ₂ Ｓｂ₂ Ｔｅ₅ 膜５に隣接して残留応力を導入されたＧｅＮ膜８-1を設けることにより、製造直後における記録膜を非晶質状態から結晶質状態へと容易に変化させることが可能となることが確認された。また、相変化記録膜の成膜時に、スパッタリングガス圧を高めることにより、記録膜原料の急冷度を低減し、作製直後における相変化記録膜の非晶質状態の過剰な安定性を低減可能であることが確認された。
【０１３７】
次に、サンプルＩについて上記測定を行ったところ、１回目のオーバーライト記録でＣ／Ｎ値を４５ｄＢとすることができた。また、オーバーライト記録を３回繰返すことにより、Ｃ／Ｎ値を５２ｄＢとすることができた。また、サンプルＪについて上記測定を行ったところ、１回目のオーバーライト記録の直後にＣ／Ｎ値は５１ｄＢに達し、２回目のオーバーライト記録でＣ／Ｎ値を５２ｄＢとすることができた。以上の結果から、ＧｅＮ膜８-1及びＧｅＮ膜８-2のいずれを設けた場合においても同様の効果が得られることが確認された。
【０１３８】
次に、サンプルＫ，Ｌについて上記測定を行ったところ、ともに１回目のオーバーライト記録でＣ／Ｎ値を５２ｄＢ以上とすることができた。以上の結果から、ＧｅＮ膜８-1及びＧｅＮ膜８-2の双方を設けることにより、一方のみに設けた場合に比べて、製造直後において非晶質状態にある記録膜をさらに容易に結晶質状態へと変化させることが可能となることが確認された。
【０１３９】
上述したように、本発明の実施例に係るサンプルＡ〜Ｌによると、製造直後において非晶質状態にある記録膜を容易に結晶質状態へと変化させることができた。さらに、本発明の実施例に係るサンプルＡ〜Ｌにおいては、オーバーライト記録時に記録マークの消去率が著しく向上した。これは、本発明の実施例に係るサンプルＡ〜Ｌには結晶化誘起層が設けられているため、結晶核の生成が促進され、非晶質状態から結晶質状態への変化が高い効率で生じたことによると考えられる。
【０１４０】
以上示したように、本発明によると、基板上に相変化記録膜を成膜する際に、スパッタガスとしてＫｒガス或いはＸｅガスを用い、スパッタガス圧を高めることにより、基板面へと衝突する記録膜原料原子或いは分子の速度が低減される。そのため、記録膜原料の急冷度が低減され、作製される相変化記録膜は、適度な安定性を有する非晶質状態となる。また、本発明によると、相変化記録膜と接するように、残留応力を導入された結晶化誘起層が設けられる。そのため、相変化記録膜の結晶化誘起層との界面において結晶核の生成が促進される。したがって、本発明によると、初期結晶化を行う必要がなく、作製直後からオーバーライト記録が可能な無初期化型相変化光記録媒体を製造することが可能となる。
【０１４１】
また、本発明によると、スパッタリング条件の僅かな変更により、上記非晶質状態の安定性を制御可能である。したがって、容易に実現可能であり、かつ制御も簡単である。さらに、本発明によると、結晶化誘起層、相変化記録膜、金属反射層等を連続的に成膜することが出来るため、無初期化型相変化光記録媒体を高い効率で製造可能である。
【０１４２】
なお、上記実施例においては、無初期化型とすることによる効果が顕著なＬｔｏＨメディアについて説明したが、ＨｔｏＬメディアであっても、本発明の方法により無初期化型の相変化光記録媒体を製造可能であることは言うまでもない。
【０１４３】
また、上記実施例においては、相変化光記録媒体を製造する際に、相変化記録膜の材料としてＧｅＳｂＴｅ系材料を用いたが、本発明はこれに限られるものではなく、ＩｎＳｂＴｅ系材料、ＡｇＩｎＳｂＴｅ系材料、及びＩｎＳｅ系材料等、様々な相変化記録材料を用いた場合においても同様の効果を得ることができるのは言うまでもない。
【０１４４】
さらに、上記実施例においては、相変化記録膜をスパッタリングにより成膜する際に、スパッタガスとしてＫｒガスを用いた場合について説明したが、Ｘｅガスを用いた場合においても同様の効果を得ることができるのは言うまでもない。
【０１４５】
【発明の効果】
以上示したように、本発明によると、基板上に相変化記録膜を成膜する際に、スパッタガスとしてＫｒガス或いはＸｅガスを用い、スパッタガス圧を高めることにより、基板面へと衝突する記録膜原料原子或いは分子の速度が低減される。そのため、記録膜原料の急冷度が低減され、作製される相変化記録膜は、適度な安定性を有する非晶質状態となる。また、本発明によると、相変化記録膜と接するように、結晶化誘起層が設けられる。そのため、相変化記録膜の結晶化誘起層との界面において結晶核の生成が促進される。したがって、本発明によると、記録膜の初期結晶化を必要とすることなく製造直後からオーバーライト記録が可能な無初期化型相変化光記録媒体を実現可能とする新規な相変化光記録媒体の製造方法が提供される。
【図面の簡単な説明】
【図１】本発明の一実施形態に係る無初期化型相変化光記録媒体を概略的に示すの断面図。
【図２】本発明の他の実施形態に係る無初期化型相変化光記録媒体を概略的に示す断面図。
【図３】本発明のさらに他の実施形態に係る無初期化型相変化光記録媒体を概略的に示す断面図。
【図４】本発明のさらに他の実施形態に係る無初期化型相変化光記録媒体を概略的に示す断面図。
【図５】本発明の実施例に係る相変化光記録媒体の製造に用いられるスパッタ装置を概略的に示す図。
【図６】本発明の実施例において用いられる光ディスクドライブ装置を概略的に示す図。
【図７】本発明の実施例に係る相変化光記録媒体における、情報の記録・消去・再生に必要なレーザ光のパワーを示すグラフ。
【符号の説明】
１-1〜1-4 …相変化光記録媒体
２…基板
３…半透明干渉層
４-n…誘電体膜
５…相変化記録膜
６…金属反射層
７…保護膜
８-1，８-2…結晶化誘起層
９…基台
１０-n，１１…バルブ
１２…真空ターボポンプ
１３-n…ターゲット
１４-n…電極
１５-n…シャッタ
１６…ＲＦ電源
１７…切替スイッチ
２１…チャンバー
３２…スピンドルモータ
３３…光学ヘッド
３４…リニアモータ
３５…変調回路
３６…入力装置
３７…レーザドライバ
３８…プリアンプ
３９…２値化回路
４０…復調回路
４１…出力装置
４３〜４６…制御系[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a phase change optical recording medium having a phase change recording film that reversibly changes phase between crystalline and amorphous when irradiated with predetermined light.the body'sIn particular, a non-initialization type phase change optical recording medium capable of overwriting recording immediately after production without requiring initial crystallization of the recording film.the body'sIt relates to a manufacturing method.
[0002]
[Prior art]
In recent years, optical disks have attracted attention as large-capacity memories. Optical discs can be played back only, such as CDs that can only be played back and cannot be recorded, once-writes such as CD-Rs that can be recorded only once, and recording / erasing information freely It can be roughly divided into three types of rewritable types used for an external memory of a computer. Among them, the rewritable type is particularly attracting attention for its wide use.
[0003]
There are two main types of rewritable optical discs: a magneto-optical disc and a phase change optical disc. Among these, the phase change optical disc uses a recording film that reversibly changes between amorphous and crystalline by irradiation with a laser beam or the like, and has an amorphous recording mark and a crystalline background. Reproduction is performed using the difference in reflectance between the two. This amorphous state is formed by heating and rapidly cooling the recording film above the melting point, and the crystalline state is formed by heating the recording film above the crystallization temperature and below the melting point. Therefore, the phase change optical disc has an advantage that information can be rewritten freely by controlling the intensity of the laser beam applied to the recording film.
[0004]
In general, a phase change optical disk has a structure in which a recording film is formed on a disk-shaped plastic substrate made of polycarbonate or the like. For the formation of the recording film on the substrate, a vacuum film forming method such as a sputtering method or a vapor deposition method is usually used. According to these film forming methods, when the raw material is deposited on the substrate surface, Source molecules collide with the substrate at a very high velocity. As a result, the raw material is rapidly cooled as soon as it adheres to the substrate, that is, the raw material is melted and rapidly cooled, and the recording film immediately after film formation becomes amorphous.
[0005]
As described above, the amorphous state corresponds to the recording state. Therefore, in the phase change optical disk immediately after being manufactured, the entire recording film is in a recording state. In a phase change optical disk, it is ideal that a recording mark in an amorphous state and a background in a crystalline state can be written by the first overwriting immediately after the fabrication. However, when the recording film is formed by the above method, the amorphous state of the recording film immediately after the film formation is very stable in terms of energy. Therefore, in the first overwrite recording by the optical disk drive, the crystalline state cannot be obtained.
[0006]
For the above reasons, in a phase change optical disk, the entire recording film is usually crystallized by an initial crystallization apparatus using a high-power laser before recording with an optical disk drive. The recording film is crystallized by the initial crystallization apparatus by, for example, the following method.
[0007]
First, a laser of several W class output such as an Ar gas laser is used, and the laser beam outputted from this laser is condensed on the recording film by the objective lens so that the spot diameter becomes several tens of μm. While rotating the optical disk, the laser beam is irradiated onto the recording film, and the beam spot is moved relative to the rotation axis in the radial direction of the disk. Thereby, the entire recording film can be made crystalline. Here, since the track pitch of the optical disk is usually 0.5 to 1.6 μm, several tens of tracks can be crystallized simultaneously.
[0008]
By the way, phase change optical disks are roughly classified into two types based on the relationship between the crystallinity of the recording film and the reflectance. That is, a phase change optical disc has a high to low (hereinafter referred to as HtoL) medium having a lower reflectance in an amorphous state (recording state) than a crystalline state (erased state), and a crystalline state (erased state). In contrast, the amorphous state (recorded state) is classified as a Low to High (hereinafter referred to as LtoH) medium having a higher reflectance.
[0009]
In HtoL media, the recording film after the initial crystallization has a high reflectance because it is in a crystalline state. Therefore, in the case of HtoL media, when overwrite recording is performed with an optical disk drive immediately after initial crystallization, a sufficient amount of reflected light is obtained, and servo control does not become unstable. In addition, in an optical disc on which overwrite recording has been performed, the recording mark portion is in an amorphous state, and thus the reflectance is lowered. In general, it is assumed that the recorded portion and the unrecorded portion are approximately half. . Therefore, in the optical disk on which overwrite recording is performed, the average value of the reflectance is about the middle between the reflectance in the crystalline state and the reflectance in the amorphous state, and does not hinder the servo control.
[0010]
On the other hand, in the LtoH media, the recording film immediately after the initial crystallization has a low reflectance. For this reason, servo control may be hindered with LtoH media. The reason will be described below.
[0011]
In recent years, with the increase in recording density of optical discs, recording marks have become increasingly finer. For this reason, in order to obtain a large signal (reflectance change amount) from a miniaturized recording mark, the LtoH media tends to reduce the reflectance in the crystalline state.
[0012]
This will be described using the degree of modulation. The reflectance of the recording film in the amorphous state is represented by R._a The reflectance of the recording film in the crystalline state is R_c The degree of modulation is (R_a -R_c ) / R_a Defined by Since the degree of modulation is an indicator of signal magnitude, R_c By making the value smaller, the degree of modulation can be made larger, that is, a larger signal can be obtained.
[0013]
At present, it is assumed that the track pitch is set to about 0.6 μm and the bit pitch is set to about 0.28 μm with the increase in recording density of DVD-RAM and the like. If mark edge recording is performed under such conditions, the C / N value (Carrier to Noise Ratio) needs to be 53 dB or more in order to reduce the reproduction jitter value to 8% or less. This is calculated, for example, R_a 0.2, R_c Is 0.04, and the modulation degree is 80% or more.
[0014]
However, in LtoH media, if the reflectance of the recording film immediately after the initial crystallization is 0.04 or less, sufficient reflected light quantity cannot be obtained when performing overwrite recording with an optical disk drive, and servo control becomes unstable. Become. When information is recorded in such a state, problems such as failure to reproduce the recorded information occur.
[0015]
An uninitialized type phase change optical disc is expected as a solution to the problems occurring in the LtoH media. An uninitialized type phase change optical disk enables overwriting by an optical disk drive immediately after fabrication without performing initial crystallization of a recording film. According to the LtoH type non-initialization type phase change optical disc, the first overwrite recording is performed on the recording film in an amorphous state immediately after the production. That is, the recording is performed on the recording film whose entire surface is in a recording state with a high reflectance. Therefore, according to the LtoH type non-initialization type phase change optical disk, it is considered that the servo control is not hindered during the first overwrite recording.
[0016]
[Problems to be solved by the invention]
  As described above, according to the non-initialization type phase change optical disk, it is considered that overwrite recording can be performed without performing initial crystallization.
  The present invention relates to a non-initialization type phase change optical recording medium capable of overwriting recording immediately after production without requiring initial crystallization of the recording film.BodyIt is an object of the present invention to provide a novel method of manufacturing a phase change optical recording medium that can be realized.
[0018]
[Means for Solving the Problems]
  To solve the above problem,The present invention comprises a phase change recording film that reversibly changes phase between crystalline and amorphous when irradiated with a light beam, and is disposed in contact with the phase change recording film.WasA method of manufacturing an uninitialized phase change optical recording medium having a crystallization inducing layer, wherein the phase change recording film is made of Kr gas or Xe gas as a sputtering gas, and 5 × 10 5^-2The crystallization inducing layer is formed by vacuum sputtering under a sputtering gas pressure of torr or higher.ZnS / SiO ₂ film5 × 10 using Ar gas as the sputtering gas^-FourThere is provided a method for producing an uninitialized phase change optical recording medium, characterized in that a film is formed by vacuum sputtering under a sputtering gas pressure of torr or less.
[0019]
  Furthermore, the present invention provides a phase change recording film that reversibly changes phase between crystalline and amorphous when irradiated with a light beam, and is disposed in contact with the phase change recording film.WasA method of manufacturing an uninitialized phase change optical recording medium having a crystallization inducing layer, wherein the phase change recording film is made of Kr gas or Xe gas as a sputtering gas, and 5 × 10 5^-2The crystallization inducing layer is formed by vacuum sputtering under a sputtering gas pressure of torr or higher.GeN filmUsing Ar gas as the sputtering gas, N₂GaTheThere is provided a method for producing an uninitialized phase change optical recording medium, characterized in that a film is formed by vacuum sputtering while being supplied.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
FIG. 1 shows a cross-sectional view of an uninitialized phase change optical recording medium according to an embodiment of the present invention. A phase change optical recording medium 1-1 shown in FIG. 1 is an LtoH type phase change optical recording medium, and has a translucent interference layer 3, a dielectric film 4-1, a crystallization inducing layer 8- 1. A phase change recording film 5, a dielectric film 4-2, a metal reflection layer 6, and a protective film 7 are sequentially laminated.
[0021]
The principle of the present invention will be described below with reference to FIG.
As described above, when the phase change recording film 5 is formed on the substrate 2 by a sputtering method or the like, the recording film 5 is in an amorphous state with an excessively high stability immediately after the production. Therefore, the phase change recording medium manufactured by the conventional method needs to be subjected to initial crystallization.
[0022]
The inventors of the present invention have one of the reasons why the stability of the amorphous state of the recording film 5 is excessively high immediately after manufacture, because the source atoms or source molecules of the recording film 5 collide with the substrate surface at an excessive speed. I thought. That is, when the recording film raw material is deposited on the substrate 2, the raw material atoms or raw material molecules collide with the substrate 2 at a very high speed, so that the raw material is rapidly cooled from a very high temperature at the moment when it is deposited on the substrate 2. Is done. This extremely high cooling rate excessively increases the stability of the amorphous state in the recording film 5 immediately after film formation.
[0023]
Here, the speed of the raw material atoms or raw material molecules of the recording film 5 is considered to depend on the mean free path. Therefore, by reducing the mean free path of the source atoms or source molecules, it becomes possible to reduce the incident energy of the source atoms or source molecules with respect to the substrate surface.
[0024]
When the recording film 5 is formed on the substrate 2 by the vacuum sputtering method, as a method of reducing the mean free process, for example, the sputtering gas pressure such as Kr gas is increased, and the source atoms or source molecules and the sputtering gas It is possible to increase the number of collisions. Normally, the recording film 5 of the phase change recording medium 1-1 is 5 × 10.^-3It is formed by sputtering under a vacuum of about torr. The inventors of the present invention formed the recording film 5 using various raw materials, and in any of the raw materials, by increasing the sputtering gas pressure, the stability of the amorphous state immediately after the recording film was formed. It was confirmed that can be reduced.
[0025]
It is preferable to use Kr gas or Xe gas as the sputtering gas. Ar, Kr, and Xe are homologous elements, and are all chemically inert, but in the periodic table, Kr is an element that is one cycle higher than Ar, and Xe is two cycles higher than Ar. Elements. That is, Kr and Xe have a larger atomic weight than Ar. Therefore, when Kr gas or Xe gas is used as the sputtering gas, the kinetic energy of the source atoms or source molecules can be further reduced as compared with the case where Ar gas is used. That is, the stability of the amorphous state immediately after the recording film is formed can be further reduced.
[0026]
The sputtering gas pressure is 5 × 10.^-2Torr or more is preferable. Sputtering gas pressure is 5 × 10^-2By setting it to more than torr, the kinetic energy of the raw material atoms or raw material molecules can be further reduced. The sputtering gas pressure is 5 × 10.^-1Torr or less is preferable. If the sputtering gas pressure is excessively increased, the amount of sputtering gas mixed into the recording film 5 may become excessive.
[0027]
In the phase change optical recording medium 1-1, a crystallization inducing layer 8-1 that is transparent and has residual stress introduced is provided adjacent to the recording film 5. When such a crystallization inducing film 8-1 is provided, the recording film 5 is changed from an amorphous state to a crystalline state with lower energy than when the crystallization inducing layer 8-1 is not provided. It becomes possible. This is because residual stress is introduced into the crystallization inducing layer 8-1. That is, it is considered that, when the recording film 5 is melted and cooled, generation of crystal nuclei is promoted at the interface of the recording film 5 with the crystallization inducing layer 8-1.
[0028]
The crystallization inducing layer is not necessarily provided between the substrate 2 and the phase change recording film as long as it is in contact with the phase change recording film 5. FIG. 2 schematically shows a cross-sectional view of an uninitialized phase change optical recording medium according to another embodiment of the present invention. As shown in this figure, a crystallization inducing layer 8-2 may be provided on the phase change recording film 5. Even in this case, the above-described effects can be obtained.
[0029]
More preferably, the crystallization inducing layer is provided on both sides of the phase change recording film. FIG. 3 schematically shows a cross-sectional view of an uninitialized phase change optical recording medium according to still another embodiment of the present invention. As shown in this figure, the crystallization inducing layers 8-1 and 8-2 may be provided on both the upper and lower sides of the phase change recording film 5 so as to be in contact with the phase change recording film 5. In this case, the above-described generation of crystal nuclei is further promoted.
[0030]
The crystallization-inducing layers 8-1 and 8-2 are formed of, for example, N in Ar gas when a film is formed by vacuum sputtering using Ar gas as a sputtering gas.₂ Gas or H₂ It can be obtained by mixing gases. When sputtering is performed under such conditions, nitrogen and hydrogen are taken into the crystallization induction layer. Nitrogen molecules, hydrogen molecules, or nitrogen atoms or hydrogen atoms give residual stress to the crystallization-inducing layer, which may make it possible to obtain an uninitialized phase change optical recording medium that does not require initial crystallization. .
[0031]
For the crystallization inducing layers 8-1 and 8-2, for example, a material such as Ge can be used. In particular, using a Ge target, N in Ar gas₂ It is preferable to perform sputtering by mixing gases to form the crystallization inducing layers 8-1 and 8-2, that is, to make the crystallization inducing layers 8-1 and 8-2 into GeN films. In this case, the effect of accelerating the generation of the above-described crystal nuclei is much greater than when the crystallization inducing layers 8-1 and 8-2 are made of other materials.
[0032]
When the crystallization inducing layers 8-1 and 8-2 are made of GeN films, N with respect to the flow rate of Ar gas₂ The ratio of gas flow rates is preferably 0.3 or more. Since pure Ge is a semiconductor, it has a predetermined optical band gap. For this reason, red semiconductor laser light used for recording / erasing information is absorbed to some extent. On the other hand, the band gap can be widened by increasing the amount of nitrogen contained in the Ge film. That is, absorption of red laser light can be prevented.
[0033]
N against Ar gas flow rate₂ The gas flow ratio depends on the RF power input during sputtering, but when it is 0.3 or more, the band gap can be made wider than 2 eV, and as a result, red laser light is absorbed. Can be prevented. In this case, a sufficient amount of residual stress can be introduced into the crystallization inducing layers 8-1 and 8-2.
[0034]
The flow rate ratio is preferably 10 or less. When the flow rate ratio exceeds 10, sputtering may be difficult. Also too N₂ If the gas flow ratio is high, the Ge target is nitrided, and the reproducibility of the GeN film formed by sputtering may be reduced.
[0035]
As described above, the application of the residual stress to the crystallization inducing layers 8-1 and 8-2 by containing nitrogen or hydrogen has been described. However, other methods can be used. The crystallization inducing layers 8-1 and 8-2 can be formed, for example, by sputtering while reducing the sputtering gas pressure.
[0036]
The sputtering gas pressure is 5 × 10^-FourTorr or less is preferable. Sputtering gas pressure is 5 × 10^-FourBy setting it to less than torr, it becomes possible to introduce a sufficient amount of residual stress to the crystallization-inducing layer 8-1, and as a result, an uninitialized phase change optical recording medium that does not require initial crystallization is obtained. May be possible. The sputtering gas pressure is 5 × 10.^-FiveTorr or more is preferable. When the sputtering gas pressure is excessively lowered, it may be difficult to perform sputtering.
[0037]
It is sufficient that the crystallization-inducing layers 8-1 and 8-2 have a thickness of about 5 to 200 angstroms. As will be described later, when the crystallization-inducing layers 8-1 and 8-2 also serve as the dielectric films 4-1 and 4-2, the thickness may be about 2000 angstroms at the maximum.
[0038]
The crystallization inducing layers 8-1 and 8-2 may also serve as the dielectric films 4-1 and 4-2. FIG. 4 schematically shows a cross-sectional view of an uninitialized phase change recording medium according to still another embodiment of the present invention. In the optical recording medium 1-4 shown in FIG. 4, residual stress is introduced into at least one of the dielectric films 4-1, 4-2. That is, the dielectric films 4-1 and 4-2 function as crystallization inducing layers, and can promote the generation of the above-described crystal nuclei.
[0039]
As a method for introducing residual stress into the dielectric films 4-1 and 4-2, the dielectric films 4-1 and 4-2 can be formed under the sputtering gas pressure. It is also possible to introduce residual stress by incorporating nitrogen or hydrogen into the dielectric films 4-1, 4-2. However, in this case, the ability of the dielectric films 4-1 and 4-2 to protect the recording film 5 from heat can be impaired. Therefore, when introducing residual stress by containing nitrogen or hydrogen, it is preferable to separately provide crystallization inducing layers 8-1 and 8-2 in addition to the dielectric films 4-1 and 4-2.
[0040]
Hereinafter, materials used in the non-initializing phase change optical recording media 1-1 to 1-4 will be described.
In the optical recording media 1-1 to 1-4, the substrate 2 is a transparent substrate made of synthetic resin such as polycarbonate or glass.
[0041]
Further, in the optical recording media 1-1 to 1-4, the phase change recording film 5 needs to be made of a material that reversibly changes phase between amorphous and crystalline by light irradiation. is there. As a material constituting the phase change recording layer, for example, Ge₂ Sb₂ Te_Five And a ternary alloy composed of Ge, Sb and Te, or a ternary alloy composed of In, Sb and Te.
[0042]
Recording on the phase change recording film 5 is performed by heating the recording film 5 to a melting point or higher and then rapidly cooling it to an amorphous state. The recorded information is erased by heating the recording film 5 in an amorphous state to a crystalline state by heating it to a temperature above the crystallization temperature and below the melting point. The phase change recording film 5 needs to be thin enough to be melted by irradiation with laser light or the like. Therefore, the phase change recording film 5 is usually formed to a thickness of about 50 to 300 angstroms.
[0043]
The dielectric films 4-1 and 4-2 are provided to prevent the recording film 5 from evaporating when the recording film 5 is irradiated with laser light or the like. That is, by providing the dielectric films 4-1 and 4-2, it is possible to prevent the recording film 5 from being punched and to protect the recording film 5 from heat.
[0044]
As a material used for the dielectric films 4-1, 4-2, for example, ZnS.SiO₂ Mixture, SiO₂ TiO₂ And Al₂ O_Three And light transmissive dielectrics such as In the optical recording medium 1-1, the dielectric film 4-1 is designed to optically enhance the reproduction signal by a synergistic effect with the translucent interference layer 3 and the metal reflection layer 6. , Having a thickness of about 500 to 3000 angstroms.
[0045]
The dielectric film 4-2 is formed thin to promote cooling of the recording film 5 melted by irradiation with laser light or the like, and is usually controlled to a thickness of about 50 to 300 angstroms. In recent years, with an increase in data transfer speed, an increase in recording speed has been demanded. In this case, since the sensitivity needs to be improved, a phase-change optical recording medium of a slow cooling (high heat holding ability) type instead of a rapid cooling (low heat holding ability) type has been studied. Accordingly, when the optical recording media 1-1 to 1-4 are of the slow cooling type, the dielectric film 4-2 is usually formed to a thickness of about 300 to 3000 angstroms in order to increase the heat holding capability. The
[0046]
Examples of the material used for the metal reflective layer 6 include an AlMo alloy. The metal reflection layer 6 is usually formed to a thickness of about 500 to 3000 angstroms in order to enhance the reproduction signal and enhance heat dissipation.
[0047]
Moreover, Au etc. can be mentioned as a material used for the translucent interference layer 3. FIG. The translucent interference layer 3 needs to be thin to some extent so that the laser beam or the like irradiated from the substrate 2 side can reach the recording film 5. The translucent interference layer 3 needs a certain thickness in order to enhance the reproduction signal by causing light interference between the translucent interference layer 3 and the metal reflection layer 6. Therefore, the semi-transparent interference layer 3 is usually formed to about 20 to 200 angstroms.
[0048]
【Example】
Examples of the present invention will be described below.
Example 1
Using the sputtering apparatus shown in FIG. 5, the phase change optical recording medium 1-4 shown in FIG. 4 was produced. FIG. 5 is a diagram schematically showing a sputtering apparatus used for manufacturing a phase change optical recording medium according to an embodiment of the present invention.
[0049]
In producing the phase change optical recording medium 1-4, first, a polycarbonate having a diameter of 120 mm and a thickness of 0.6 mm, and a spiral groove having a width of 0.6 μm formed on one main surface. The disk 2 was held on a disk-shaped base 9 provided in the chamber 21 so that the surface on which the groove was formed faced downward. The base 9 can be rotated while holding the disk 2.
[0050]
Next, by opening the valve 11 and driving the vacuum turbo pump 12, the inside of the chamber 21 is set to 10.^-6The pressure was reduced to torr. Further, while rotating the base 9 at a speed of 60 rpm, the valve 10-1 was opened and Ar gas was introduced into the chamber 21. The Ar gas pressure in the chamber is 5 × 10 5 by controlling the Ar flow rate using a mass flow controller (not shown) without changing the open state of the valve 11 and the exhaust capacity of the vacuum turbo pump 12.^-3Torr.
[0051]
Next, the RF power source 16 and the electrode 14-1 were electrically connected using the changeover switch 17, and RF power of 13.56 MHz and 150 W was supplied to the electrode 14-1. As described above, sputtering of the Au target 13-1 disposed on the electrode 14-1 with Ar gas was started. After pre-sputtering for about 1 minute, the shutter 15-1 disposed above the Au target 13-1 was opened. After a predetermined time, the changeover switch 17 was used to electrically insulate the RF power supply 16 from the electrode 14-1, and the shutter 15-1 was closed. As described above, the Au film 3 having a thickness of 100 Å was formed as the translucent interference layer 3 on the disk 2.
[0052]
After forming the Au film 3, the valve 10-1 was closed, and Ar gas and Au atoms remaining in the chamber 21 were evacuated using the vacuum turbo pump 12. After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is reduced to 5 × 10.^-FourControlled to torr.
[0053]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 4 minutes and 30 seconds, the RF power source 16 and the electrode 14-2 were electrically insulated using the changeover switch 17, and the shutter 15-2 was closed. As described above, a ZnS / SiO film having a thickness of 850 angstroms is formed on the Au film 3 as the dielectric film 4-1.₂ A film 4-1 was formed. ZnS / SiO₂ Residual stress is introduced into the film 4-1. That is, ZnS / SiO₂ The film 4-1 also serves as a crystallization inducing layer.
[0054]
ZnS / SiO₂ After the film 4-1 is formed, the valve 10-1 is closed and the Ar gas remaining in the chamber 21 and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-2 is opened, and Kr gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Kr gas pressure in the chamber is set to 5 × 10.^-2Controlled to torr.
[0055]
Next, the RF power source 16 and the electrode 14-3 were electrically connected using the changeover switch 17, and 200 W of RF power was supplied to the electrode 14-3. As described above, the Ge disposed on the electrode 14-3.₂ Sb₂ Te_Five Sputtering of the target 13-3 with Kr gas was started. After pre-sputtering for about 1 minute, Ge₂ Sb₂ Te_Five The shutter 15-3 disposed above the target 13-3 was opened. After 40 seconds, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-3, and the shutter 15-3 was closed. As described above, ZnS / SiO₂ As a phase change recording film 5 on the film 4-1, a Ge film having a thickness of 100 angstroms was formed.₂ Sb₂ Te_Five A film 5 was formed.
[0056]
Ge₂ Sb₂ Te_Five After the film 5 is formed, the valve 10-2 is closed, and the Kr gas remaining in the chamber 21 and Ge₂ Sb₂ Te_Five The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-3Torr controlled.
[0057]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 3 minutes, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-2, and the shutter 15-2 was closed. As described above, Ge₂ Sb₂ Te_Five As a dielectric film 4-2 on the film 5, ZnS / SiO with a thickness of 300 angstroms₂ A film 4-2 was formed.
[0058]
ZnS / SiO₂ After the film 4-2 is formed, the valve 10-1 is closed, and Ar gas remaining in the chamber 21 and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is reduced to 5 × 10.^-3Controlled to torr.
[0059]
Next, the RF power source 16 and the electrode 14-4 were electrically connected using the changeover switch 17, and 200 W of RF power was supplied to the electrode 14-4. As described above, sputtering of the AlMo target 13-4 disposed on the electrode 14-4 with Ar gas was started. After pre-sputtering for about 1 minute, the shutter 15-4 disposed above the AlMo target 13-4 was opened. After 2 minutes and 30 seconds, the RF power source 16 and the electrode 14-4 were electrically insulated using the changeover switch 17, and the shutter 15-4 was closed. As described above, ZnS / SiO₂ On the film 4-2, an AlMo film 6 having a thickness of 1000 angstroms was formed as a metal reflective layer 6.
[0060]
After the respective films were formed on the disk 2 by the method described above, the disk 2 was taken out from the chamber 21. On the AlMo film 6 of the disk 2, a UV curable resin was spin-coated using a spin coater and irradiated with UV light to form a protective film 7 on the AlMo film 6.
[0061]
As described above, the Au film 3 having a thickness of 100 Å and the ZnS / SiO film having a thickness of 850 Å are formed on the disk 2.₂ Film 4-1, Ge with a thickness of 100 Å₂ Sb₂ Te_Five Film 5, ZnS / SiO with a thickness of 300 Å₂ A phase change optical recording medium 1-4 was fabricated by sequentially laminating a film 4-2, an AlMo film 6 having a thickness of 1000 angstroms, and a protective film 7 having a thickness of 8 μm. This phase change optical recording medium 1-4 is designated as Sample A.
[0062]
Ge₂ Sb₂ Te_Five The Kr gas pressure during film 5 deposition is 5 × 10^-1A phase change optical recording medium 1-4 was produced in the same manner as Sample A except that the control was performed at torr. That is, compared to sample B, Ge₂ Sb₂ Te_Five The phase change optical recording medium 1-4 was produced by further reducing the rapid cooling during film formation. This phase change optical recording medium 1-4 is designated as Sample B.
[0063]
(Example 2)
ZnS / SiO₂ A phase change optical recording medium 1-4 shown in FIG. 4 was produced in the same manner as Sample A of Example 1 except that the films 4-1 and 4-2 were formed by the method described below.
[0064]
That is, after the Au film 3 was formed on the disk 2 in the same manner as the sample A, the valve 10-1 was closed and the Ar gas and Au atoms remaining in the chamber 21 were exhausted using the vacuum turbo pump 12. . After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is reduced to 5 × 10.^-3Controlled to torr.
[0065]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 8 minutes and 30 seconds, the RF power source 16 and the electrode 14-2 were electrically insulated using the changeover switch 17, and the shutter 15-2 was closed. As described above, a ZnS / SiO film having a thickness of 850 angstroms is formed on the Au film 3 as the dielectric film 4-1.₂ A film 4-1 was formed. ZnS / SiO₂ Residual stress is not introduced into the film 4-1.
[0066]
As described above, ZnS / SiO₂ After forming the film 4-1, in the same manner as the sample A, ZnS / SiO₂ As a phase change recording film 5 on the film 4-1, a 100 Å thick Ge film₂ Sb₂ Te_Five A film 5 was formed.
[0067]
Ge₂ Sb₂ Te_Five After the film 5 is formed, the valve 10-2 is closed, and the Kr gas remaining in the chamber 21 and Ge₂ Sb₂ Te_Five The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-FourControlled to torr.
[0068]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 1 minute and 40 seconds passed, the switch 17 was used to electrically insulate the RF power source 16 and the electrode 14-2, and the shutter 15-2 was closed. As described above, Ge₂ Sb₂ Te_Five As a dielectric film 4-2 on the film 5, ZnS / SiO with a thickness of 300 angstroms₂ A film 4-2 was formed. ZnS / SiO₂ Residual stress is introduced into the film 4-2. That is, ZnS / SiO₂ The film 4-2 also serves as a crystallization inducing layer.
[0069]
Further, by the same method as shown in Example 1, ZnS / SiO₂ On the film 4-2, an AlMo film 6 and a protective film 7 were sequentially laminated to produce a phase change optical recording medium 1-4. This phase change optical recording medium 1-4 is designated as Sample C.
[0070]
Ge₂ Sb₂ Te_Five The Kr gas pressure during film 5 deposition is 5 × 10^-1Torr and Ge₂ Sb₂ Te_Five A phase change optical recording medium 1-4 was prepared in the same manner as Sample C, except that the film formation time was adjusted so that the film thickness of the film 5 was 100 angstroms. That is, compared to sample C, Ge₂ Sb₂ Te_Five The phase change optical recording medium 1-4 was produced by further reducing the rapid cooling during film formation. This phase change optical recording medium 1-4 is designated as sample D.
[0071]
(Example 3)
ZnS / SiO₂ A phase change optical recording medium 1-4 shown in FIG. 4 was produced in the same manner as Sample A of Example 1 except that the film 4-2 was formed by the method described below.
[0072]
That is, first, similarly to the sample A, the Au film 3, ZnS / SiO 2 is formed on the disk 2.₂ Film 4-1, and Ge₂ Sb₂ Te_Five A film 5 was sequentially formed.
Ge₂ Sb₂ Te_Five After the film 5 is formed, the valve 10-2 is closed, and the Kr gas remaining in the chamber 21 and Ge₂ Sb₂ Te_Five The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-FourControlled to torr.
[0073]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 1 minute and 40 seconds passed, the switch 17 was used to electrically insulate the RF power source 16 and the electrode 14-2, and the shutter 15-2 was closed. As described above, Ge₂ Sb₂ Te_Five As a dielectric film 4-2 on the film 5, ZnS / SiO with a thickness of 300 angstroms₂ A film 4-2 was formed. ZnS / SiO₂ Residual stress is introduced into the film 4-2. That is, ZnS / SiO₂ The film 4-2 also serves as a crystallization inducing layer.
[0074]
Further, by the same method as shown in Example 1, ZnS / SiO₂ On the film 4-2, an AlMo film 6 and a protective film 7 were sequentially laminated to produce a phase change optical recording medium 1-4. This phase change optical recording medium 1-4 is designated as Sample E.
[0075]
Ge₂ Sb₂ Te_Five The Kr gas pressure during film 5 deposition is 5 × 10^-1Torr and Ge₂ Sb₂ Te_Five A phase change optical recording medium 1-4 was prepared in the same manner as Sample C, except that the film formation time was adjusted so that the film 5 had a thickness of 100 angstroms. That is, compared to sample E, Ge₂ Sb₂ Te_Five The phase change optical recording medium 1-4 was produced by further reducing the rapid cooling during film formation. This phase change optical recording medium 1-4 is designated as Sample F.
[0076]
(Comparative example)
ZnS / SiO₂ Film 4-1 and Ge₂ Sb₂ Te_Five A phase change optical recording medium 1-4 shown in FIG. 4 was produced in the same manner as Sample A of Example 1 except that the film 5 was formed by the method described below.
[0077]
That is, after the Au film 3 was formed on the disk 2 in the same manner as the sample A, the valve 10-1 was closed and the Ar gas and Au atoms remaining in the chamber 21 were exhausted using the vacuum turbo pump 12. . After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is reduced to 5 × 10.^-3Controlled to torr.
[0078]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 8 minutes and 30 seconds, the RF power source 16 and the electrode 14-2 were electrically insulated using the changeover switch 17, and the shutter 15-2 was closed. As described above, a ZnS / SiO film having a thickness of 850 angstroms is formed on the Au film 3 as the dielectric film 4-1.₂ A film 4-1 was formed. ZnS / SiO₂ Residual stress is not introduced into the film 4-1.
[0079]
ZnS / SiO₂ After the film 4-1 is formed, the valve 10-1 is closed and the Ar gas remaining in the chamber 21 and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr.
[0080]
Next, the RF power source 16 and the electrode 14-3 were electrically connected using the changeover switch 17, and 200 W of RF power was supplied to the electrode 14-3. As described above, the Ge disposed on the electrode 14-3.₂ Sb₂ Te_Five Sputtering of the target 13-3 with Ar gas was started. After pre-sputtering for about 1 minute, Ge₂ Sb₂ Te_Five The shutter 15-3 disposed above the target 13-3 was opened. After 20 seconds, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-3, and the shutter 15-3 was closed. As described above, ZnS / SiO₂ As a phase change recording film 5 on the film 4-1, a Ge film having a thickness of 100 angstroms was formed.₂ Sb₂ Te_Five A film 5 was formed.
[0081]
Further, in the same manner as Sample A, Ge₂ Sb₂ Te_Five On the film 5, ZnS / SiO₂ A film 4-2, an AlMo film 6 and a protective film 7 were sequentially laminated to produce a phase change optical recording medium 1-4. This phase change optical recording medium 1-4 is used as a comparative sample.
[0082]
For samples A to F and comparative samples produced as described above, Ge₂ Sb₂ Te_Five Difference in manufacturing conditions of the film 5 and ZnS / SiO₂ Table 1 below summarizes whether or not residual stress is introduced into the films 4-1 and 4-2.
[0083]
[Table 1]

[0084]
Next, for these samples A to F and comparative samples, the stability of the amorphous state of the phase change recording film 5 immediately after fabrication was evaluated by the following method using the optical disc drive apparatus shown in FIG. . FIG. 6 is a diagram schematically showing an optical disk drive device used in the embodiment of the present invention.
[0085]
As shown in FIG. 6, the phase change optical recording medium (disk) 1-4 is held on the rotating shaft of the spindle motor 32. The disk 1-4 is rotated at a predetermined rotation speed by controlling the rotation speed of the spindle motor 32. In this embodiment, assuming the DVD-RAM, the rotation axis of the disk 1-4 and the optical head 33 are set so that the relative speed between the disk 1-4 and the optical head 33 is constant at 12 m / s. A so-called linear velocity constant method is employed in which the rotational speed of the disk 1-4 is changed according to the distance between them.
[0086]
A signal input from the input device 36 is digitized into a 1 or 0 signal in the modulation circuit 35 by 8/16 modulation when assuming a DVD-RAM, for example. The digital signal from the modulation circuit 35 is sent to the laser driver 37 and controls ON / OFF of the laser light emitted from the optical head 33. As a result, data is written on the disk 1-4.
[0087]
In this embodiment, since the disk 1-4 is a phase change optical recording medium, information is recorded on the disk 1-4, information recorded on the disk 1-4 is erased, and information recorded on the disk 1-4 is recorded. All of the reproduction is performed by irradiating a laser beam or the like.
[0088]
FIG. 7 is a graph showing the power of laser light necessary for recording / erasing / reproducing information in the phase change optical recording medium according to the embodiment of the present invention. In the figure, the horizontal axis indicates time, and the vertical axis indicates the power of the laser beam.
[0089]
As shown in FIG. 7, when recording information, the power of the laser beam is set to P._w The phase change recording film is melted and rapidly cooled to an amorphous state. When erasing recorded information, the power of the laser beam is set to P_e To an extent, the phase change recording film is crystallized by heating it to a temperature above its crystallization temperature and below its melting point. In the figure, P_r Is the power of the laser beam necessary for reproducing the recorded information. When information is written on the disk 1-4, the portion becomes amorphous. Since the reflectance is different between the amorphous part and the crystalline part, the recorded signal is detected as a difference in the amount of reflected light by scanning the disk 1-4 with a laser beam having a constant and weak power. Can do.
[0090]
Power P on disk 1-4_r A reproduction signal obtained by irradiating the laser beam is amplified by a preamplifier 38 connected to the optical head 33. The amplified reproduction signal is then digitized from an analog signal to a digital signal in a binarization circuit 39. The digitized reproduction signal is further demodulated in the demodulation circuit 40 based on the 8/16 modulation, and is output to the output device 41 as an analog signal.
[0091]
In FIG. 7, the control system 43 controls the intensity of laser light emitted from the optical head 33 via the laser driver 37, or drives the linear motor 34 via the linear motor drive control system 46, for example. Is used to control the optical head 33 to a desired position. Further, the control system 43 drives the objective lens actuator provided in the optical head 33 via the focus drive control system 44 and the track drive control system 45, thereby reducing the surface deflection of the disk 1-4 and the track eccentricity. It is used to control the position of the objective lens to follow.
[0092]
Using the optical disk driver device 30 configured as described above, the stability of the amorphous state of the phase change recording film immediately after production was evaluated for the samples A to F and the comparative sample by the following method. That is, the power P shown in FIG. 7 is obtained by the optical disk driver device 30 without performing initial crystallization on the disks 1-4 (samples A to F and comparative samples)._e Laser beam and power P for erasing_w The recording laser beam was irradiated. That is, overwrite recording was performed.
[0093]
Signal recording assumes DVD-RAM and controls the number of revolutions of spindle motor 32 so that the linear velocity is constant at 12 m / s, 8/16 modulation, duty 50%, frequency 14. Mark edge recording was performed by irradiating a laser beam of 2 MHz, and 3T, the shortest mark length, was formed on the phase change recording film. Power P_w Is 14mW and power P_e Was 5 mW.
[0094]
Further, since the phase change recording film immediately after the production is in an amorphous state, and the samples A to F and the comparative sample are all LtoH media, the reflectance of the phase change recording film immediately after the production is about 0.18. It was high enough. Therefore, in the optical disk drive device 30, servo control is possible and servo control is not disabled during the test.
[0095]
Next, recording / reproduction was performed on the disk 1-4 on which information was recorded, and the C / N value was measured using a spectrum analyzer. If the C / N value is too low, the power P_e It can be determined that the crystallization of the phase change recording film due to the irradiation of the erasing laser beam was incomplete. Therefore, in this case, overwrite recording was performed again.
[0096]
Until the sufficiently large C / N value is obtained, the above-described overwrite recording and C / N value measurement are repeated for the same region of the phase change recording film, and the phase change recording immediately after the production is performed according to the number of repetitions. The stability of the amorphous state of the film was evaluated. The results are shown below.
[0097]
First, when the above measurement was performed on the comparative sample, a spectrum of 14.2 MHz was hardly observed immediately after the first overwrite recording. When the overwrite recording and the measurement of the C / N value were repeatedly performed, the overwrite recording was required 6 times for the C / N value to reach 40 dB. Further, 15 overwrite recordings were required for the C / N value to reach 52 dB. From the above, it was confirmed that the comparative sample produced by the conventional method was excessively stable in the amorphous state of the phase change recording film immediately after production.
[0098]
Next, when the above measurement was performed on Sample A, a C / N value exceeding 40 dB could be obtained in the first overwrite recording. Further, the C / N value could be set to 52 dB by repeating the overwrite recording three times. Further, when the above measurement was performed on Sample B, the C / N value could be 50 dB in the first overwrite recording. Moreover, the C / N value could be set to 52 dB by repeating the overwrite recording twice.
[0099]
From the above results, ZnS / SiO₂ It was confirmed that by introducing residual stress to the film 4-1, the recording film immediately after the production can be easily changed from the amorphous state to the crystalline state. In addition, by increasing the sputtering gas pressure during the formation of the phase change recording film, it is possible to reduce the rapid cooling of the recording film raw material and reduce the excessive stability of the amorphous state of the phase change recording film immediately after fabrication. It was confirmed that there was.
[0100]
Next, when the above measurement was performed on sample C, the C / N value could be 40 dB in the first overwrite recording. Further, the C / N value could be set to 52 dB by repeating the overwrite recording three times. Further, when the above measurement was performed on sample D, the C / N value reached 50 dB immediately after the first overwrite recording, and the C / N value could be set to 52 dB in the second overwriting recording. From the above results, the layer for introducing residual stress is ZnS / SiO₂ Film 4-1 and ZnS / SiO₂ It was confirmed that the same effect was obtained with any of the films 4-2.
[0101]
Next, when the above measurements were performed for samples E and F, the C / N value could be set to 52 dB or more in the first overwrite recording. From the above results, ZnS / SiO₂ Film 4-1 and ZnS / SiO₂ By introducing the residual stress into both of the films 4-2, the recording film in the amorphous state immediately after manufacture is more easily changed to the crystalline state than when the residual stress is introduced into only one of the films. It was confirmed that it would be possible.
[0102]
(Example 4)
A phase change optical recording medium 1-1 shown in FIG. 1 was produced using the sputtering apparatus shown in FIG. In this example, Ge is used as the material of the target 13-4 instead of AlMo.
[0103]
In producing the phase change optical recording medium 1-1, first, an Au film 3 was formed on the disk 2 in the same manner as the sample A.
After forming the Au film 3, the valve 10-1 was closed, and Ar gas and Au atoms remaining in the chamber 21 were evacuated using the vacuum turbo pump 12. After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is reduced to 5 × 10.^-3Controlled to torr.
[0104]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 8 minutes and 30 seconds, the RF power source 16 and the electrode 14-2 were electrically insulated using the changeover switch 17, and the shutter 15-2 was closed. As described above, a ZnS / SiO film having a thickness of 850 angstroms is formed on the Au film 3 as the dielectric film 4-1.₂ A film 4-1 was formed.
[0105]
ZnS / SiO₂ After the film 4-1 is formed, the valve 10-1 is closed and the Ar gas remaining in the chamber 21 and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-3 is opened, and the Ar gas and N₂ A mixed gas with the gas is introduced into the chamber 21, and the mixed gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr. Ar gas and N₂ The flow ratio with the gas is 1: 1.
[0106]
Next, the RF power source 16 and the electrode 14-4 were electrically connected using the changeover switch 17, and 250 W of RF power was supplied to the electrode 14-4. As described above, sputtering of the Ge target 13-4 disposed on the electrode 14-4 with Ar gas was started. After pre-sputtering for about 1 minute, the shutter 15-4 disposed above the Ge target 13-4 was opened. After 20 seconds, the switch 17 was used to electrically insulate the RF power source 16 and the electrode 14-4, and the shutter 15-4 was closed. As described above, ZnS / SiO₂ A GeN film 8-1 having a thickness of 50 angstroms was formed as a crystallization-inducing layer 8-1 on the film 4-1.
[0107]
After the GeN film 8-1 is formed, the valve 10-3 is closed, and Ar gas remaining in the chamber 21 and N₂ Gas and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-2 is opened, and Kr gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Kr gas pressure in the chamber is set to 5 × 10.^-2Controlled to torr.
[0108]
Next, the RF power source 16 and the electrode 14-3 were electrically connected using the changeover switch 17, and 200 W of RF power was supplied to the electrode 14-3. As described above, the Ge disposed on the electrode 14-3.₂ Sb₂ Te_Five Sputtering of the target 13-3 with Kr gas was started. After pre-sputtering for about 1 minute, Ge₂ Sb₂ Te_Five The shutter 15-3 disposed above the target 13-3 was opened. After 40 seconds, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-3, and the shutter 15-3 was closed. As described above, the phase change recording film 5 is formed on the GeN film 8-1 and has a thickness of 100 angstroms.₂ Sb₂ Te_Five A film 5 was formed.
[0109]
Ge₂ Sb₂ Te_Five After the film 5 is formed, the valve 10-2 is closed, and the Kr gas remaining in the chamber 21 and Ge₂ Sb₂ Te_Five The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr.
[0110]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 3 minutes, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-2, and the shutter 15-2 was closed. As described above, Ge₂ Sb₂ Te_Five As a dielectric film 4-2 on the film 5, ZnS / SiO with a thickness of 300 angstroms₂ A film 4-2 was formed.
[0111]
ZnS / SiO₂ After the film 4-2 is formed, the valve 10-1 is closed, and Ar gas remaining in the chamber 21 and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened again, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is reduced to 5 × 10.^-3Controlled to torr.
[0112]
Next, the RF power source 16 and the electrode 14-1 were electrically connected using the changeover switch 17, and 150 W of RF power was supplied to the electrode 14-1. As described above, sputtering of the Au target 13-1 disposed on the electrode 14-1 with Ar gas was started. After pre-sputtering for about 1 minute, the shutter 15-1 disposed above the Au target 13-1 was opened. After 2 minutes and 30 seconds, the RF power source 16 and the electrode 14-1 were electrically insulated using the changeover switch 17, and the shutter 15-1 was closed. As described above, ZnS / SiO₂ An Au film 6 having a thickness of 1000 angstroms was formed as an Au metal reflection layer 6 on the film 4-2.
[0113]
After the respective films were formed on the disk 2 by the method described above, the disk 2 was taken out from the chamber 21. A UV curable resin was spin-coated on the Au film 6 of the disk 2 using a spin coater, and UV light was irradiated to form a protective film 7 on the Au film 6.
[0114]
As described above, an Au film 3 having a thickness of 100 Å and a ZnS / SiO film having a thickness of 850 Å are formed on the disk 2.₂ A film 4-1, a GeN film 8-1 with a thickness of 50 angstroms, and a GeN film with a thickness of 100 angstroms₂ Sb₂ Te_Five Film 5, ZnS / SiO with a thickness of 300 Å₂ A phase change optical recording medium 1-1 was prepared by sequentially laminating a film 4-2, an Au film 6 having a thickness of 1000 angstroms, and a protective film 7 having a thickness of 8 μm. This phase change optical recording medium 1-1 is designated as sample G.
[0115]
Ge₂ Sb₂ Te_Five The Kr gas pressure during film 5 deposition is 5 × 10^-1A phase change optical recording medium 1-1 was produced in the same manner as Sample G except that it was controlled to torr. That is, compared to sample G, Ge₂ Sb₂ Te_Five The phase change optical recording medium 1-1 was produced by further reducing the rapid cooling during film formation. This phase change optical recording medium 1-1 is designated as sample H.
[0116]
(Example 5)
A phase change optical recording medium 1-2 shown in FIG. 2 was produced using the sputtering apparatus shown in FIG.
[0117]
In producing the phase change optical recording medium 1-2, first, in the same manner as in the sample G, the Au film 3 and the ZnS / SiO 2 were formed on the disk 2.₂ A film 4-1 was sequentially formed.
ZnS / SiO₂ After the film 4-1 is formed, the valve 10-1 is closed and the Ar gas remaining in the chamber 21 and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-2 is opened, and Kr gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Kr gas pressure in the chamber is set to 5 × 10.^-2Controlled to torr.
[0118]
Next, the RF power source 16 and the electrode 14-3 were electrically connected using the changeover switch 17, and 200 W of RF power was supplied to the electrode 14-3. As described above, the Ge disposed on the electrode 14-3.₂ Sb₂ Te_Five Sputtering of the target 13-3 with Kr gas was started. After pre-sputtering for about 1 minute, Ge₂ Sb₂ Te_Five The shutter 15-3 disposed above the target 13-3 was opened. After 40 seconds, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-3, and the shutter 15-3 was closed. As described above, ZnS / SiO₂ As a phase change recording film 5 on the film 4-1, a Ge film having a thickness of 100 angstroms was formed.₂ Sb₂ Te_Five A film 5 was formed.
[0119]
Ge₂ Sb₂ Te_Five After the film 5 is formed, the valve 10-2 is closed, and the Kr gas remaining in the chamber 21 and Ge₂ Sb₂ Te_Five The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-3 is opened, and the Ar gas and N₂ A mixed gas with the gas is introduced into the chamber 21, and the mixed gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr. Ar gas and N₂ The flow ratio with the gas is 1: 1.
[0120]
Next, the RF power source 16 and the electrode 14-4 were electrically connected using the changeover switch 17, and 250 W of RF power was supplied to the electrode 14-4. As described above, sputtering of the Ge target 13-4 disposed on the electrode 14-4 with Ar gas was started. After pre-sputtering for about 1 minute, the shutter 15-4 disposed above the Ge target 13-4 was opened. After 20 seconds, the switch 17 was used to electrically insulate the RF power source 16 and the electrode 14-4, and the shutter 15-4 was closed. As described above, Ge₂ Sb₂ Te_Five On the film 5, a GeN film 8-2 having a thickness of 50 Å was formed as a crystallization inducing layer 8-1.
[0121]
After the GeN film 8-2 is formed, the valve 10-3 is closed, and the Ar gas remaining in the chamber 21 and N₂ Gas and ZnS / SiO₂ The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr.
[0122]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 3 minutes, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-2, and the shutter 15-2 was closed. As described above, the dielectric film 4-2 is formed on the GeN film 8-2 as a ZnS / SiO2 film having a thickness of 300 angstroms.₂ A film 4-2 was formed.
[0123]
Further, in the same manner as Sample G, ZnS / SiO₂ An Au film 6 and a protective film 7 were sequentially laminated on the film 4-2 to prepare a phase change optical recording medium 1-2. This phase change optical recording medium 1-2 is designated as Sample I.
[0124]
Ge₂ Sb₂ Te_Five The Kr gas pressure during film 5 deposition is 5 × 10^-1A phase change optical recording medium 1-2 was produced in the same manner as Sample I except that the torr was controlled. That is, compared to sample I, Ge₂ Sb₂ Te_Five The phase change optical recording medium 1-2 was produced by further reducing the rapid cooling during film formation. This phase change optical recording medium 1-2 is designated as Sample J.
[0125]
(Example 6)
A phase change optical recording medium 1-3 shown in FIG. 3 was produced using the sputtering apparatus shown in FIG.
[0126]
In producing the phase change optical recording medium 1-3, first, similarly to the sample G, the Au film 3, ZnS / SiO 2 is formed on the disk 2.₂ Film 4-1, GeN film 8-1, and Kr gas pressure 5 × 10^-2Ge as torr₂ Sb₂ Te_Five A film 5 was sequentially formed.
[0127]
Ge₂ Sb₂ Te_Five After the film 5 is formed, the valve 10-2 is closed, and the Kr gas remaining in the chamber 21 and Ge₂ Sb₂ Te_Five The molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-3 is opened, and the Ar gas and N₂ A mixed gas with the gas is introduced into the chamber 21, and the mixed gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr. Ar gas and N₂ The flow ratio with the gas is 1: 1.
[0128]
Next, the RF power source 16 and the electrode 14-4 were electrically connected using the changeover switch 17, and 250 W of RF power was supplied to the electrode 14-4. As described above, sputtering of the Ge target 13-4 disposed on the electrode 14-4 with Ar gas was started. After pre-sputtering for about 1 minute, the shutter 15-4 disposed above the Ge target 13-4 was opened. After 20 seconds, the switch 17 was used to electrically insulate the RF power source 16 and the electrode 14-4, and the shutter 15-4 was closed. As described above, Ge₂ Sb₂ Te_Five A GeN film 8-1 having a thickness of 50 Å was formed on the film 5 as a crystallization-inducing layer 8-1.
[0129]
After the GeN film 8-1 is formed, the valve 10-3 is closed, and Ar gas remaining in the chamber 21 and N₂ The gas and Ge molecules were evacuated using a vacuum turbo pump 12. After exhausting, the valve 10-1 is opened, Ar gas is introduced into the chamber 21 while controlling the flow rate with a mass flow controller, and the Ar gas pressure in the chamber is set to 5 × 10.^-3Controlled to torr.
[0130]
Next, the RF power source 16 and the electrode 14-2 were electrically connected using the changeover switch 17, and 600 W of RF power was supplied to the electrode 14-2. As described above, ZnS / SiO 2 disposed on the electrode 14-2.₂ Sputtering of the target 13-2 with Ar gas was started. After pre-sputtering for about 1 minute, ZnS / SiO₂ The shutter 15-2 disposed above the target 13-2 was opened. After 3 minutes, the switch 17 was used to electrically insulate the RF power supply 16 and the electrode 14-2, and the shutter 15-2 was closed. As described above, the dielectric film 4-2 is formed on the GeN film 8-1 as a ZnS / SiO2 film having a thickness of 300 angstroms.₂ A film 4-2 was formed.
[0131]
Further, in the same manner as Sample G, ZnS / SiO₂ An Au film 6 and a protective film 7 were sequentially laminated on the film 4-2 to prepare a phase change optical recording medium 1-3. This phase change optical recording medium 1-3 is designated as sample K.
[0132]
Ge₂ Sb₂ Te_Five The Kr gas pressure during film 5 deposition is 5 × 10^-1A phase change optical recording medium 1-3 was produced in the same manner as Sample K except that the control was performed at torr. That is, compared to sample K, Ge₂ Sb₂ Te_Five The phase change optical recording medium 1-3 was produced by further reducing the degree of rapid cooling during the formation of the film 5. This phase change optical recording medium 1-3 is designated as sample L.
[0133]
For samples G to L and comparative samples prepared as described above, Ge₂ Sb₂ Te_Five The differences in the manufacturing conditions of the film 5 and the presence or absence of the GeN films 8-1 and 8-2 are summarized in Table 2 below.
[0134]
[Table 2]

[0135]
Next, these samples G to L were subjected to the same tests as those performed on the samples A to F and the comparative sample. As a result, for sample G, a C / N value exceeding 45 dB could be obtained in the first overwrite recording. Further, the C / N value could be set to 52 dB by repeating the overwrite recording three times. For sample H, the C / N value could be 51 dB in the first overwrite recording. Moreover, the C / N value could be set to 52 dB by repeating the overwrite recording twice.
[0136]
From the above results, Ge₂ Sb₂ Te_Five It was confirmed that the recording film immediately after manufacture can be easily changed from the amorphous state to the crystalline state by providing the GeN film 8-1 introduced with the residual stress adjacent to the film 5. It was done. In addition, by increasing the sputtering gas pressure during the formation of the phase change recording film, it is possible to reduce the rapid cooling of the recording film raw material and reduce the excessive stability of the amorphous state of the phase change recording film immediately after fabrication. It was confirmed that there was.
[0137]
Next, when the above measurement was performed on Sample I, the C / N value could be 45 dB in the first overwrite recording. Further, the C / N value could be set to 52 dB by repeating the overwrite recording three times. Further, when the above measurement was performed on sample J, the C / N value reached 51 dB immediately after the first overwrite recording, and the C / N value could be set to 52 dB in the second overwriting recording. From the above results, it was confirmed that the same effect can be obtained when either the GeN film 8-1 or the GeN film 8-2 is provided.
[0138]
Next, when the above measurements were performed on samples K and L, both C / N values could be made 52 dB or more in the first overwrite recording. From the above results, by providing both the GeN film 8-1 and the GeN film 8-2, the recording film in the amorphous state immediately after manufacture can be more easily crystalline than the case of providing only one of them. It was confirmed that it was possible to change to a state.
[0139]
As described above, according to the samples A to L according to the examples of the present invention, it was possible to easily change the recording film in the amorphous state immediately after the production to the crystalline state. Furthermore, in the samples A to L according to the examples of the present invention, the erasure rate of the recording mark was remarkably improved during overwrite recording. This is because the samples A to L according to the examples of the present invention are provided with the crystallization inducing layer, so that the generation of crystal nuclei is promoted and the change from the amorphous state to the crystalline state is highly efficient. This is thought to have occurred.
[0140]
As described above, according to the present invention, when the phase change recording film is formed on the substrate, Kr gas or Xe gas is used as the sputtering gas, and the sputtering gas pressure is increased, thereby colliding with the substrate surface. The speed of the recording film source atoms or molecules is reduced. Therefore, the rapid cooling degree of the recording film raw material is reduced, and the produced phase change recording film is in an amorphous state having appropriate stability. Further, according to the present invention, the crystallization inducing layer into which the residual stress is introduced is provided so as to be in contact with the phase change recording film. Therefore, generation of crystal nuclei is promoted at the interface between the phase change recording film and the crystallization inducing layer. Therefore, according to the present invention, it is possible to manufacture a non-initialization type phase change optical recording medium that does not require initial crystallization and can be overwritten immediately after fabrication.
[0141]
Further, according to the present invention, the stability of the amorphous state can be controlled by slightly changing the sputtering conditions. Therefore, it can be easily realized and the control is also simple. Furthermore, according to the present invention, since a crystallization-inducing layer, a phase change recording film, a metal reflective layer, and the like can be continuously formed, an uninitialized phase change optical recording medium can be manufactured with high efficiency. .
[0142]
In the above-described embodiment, the LtoH medium that has the remarkable effect of the non-initializing type has been described. However, even with the HtoL medium, the non-initializing type phase-change optical recording medium is obtained by the method of the present invention. Needless to say, it can be manufactured.
[0143]
In the above embodiment, the GeSbTe-based material is used as the material for the phase-change recording film when manufacturing the phase-change optical recording medium. However, the present invention is not limited to this, and the InSbTe-based material, AgInSbTe is used. It goes without saying that the same effect can be obtained even when various phase change recording materials such as a system material and an InSe system material are used.
[0144]
Further, in the above embodiment, the case where the Kr gas is used as the sputtering gas when the phase change recording film is formed by sputtering has been described. However, the same effect can be obtained even when the Xe gas is used. Needless to say, you can.
[0145]
【The invention's effect】
  As described above, according to the present invention, when the phase change recording film is formed on the substrate, Kr gas or Xe gas is used as the sputtering gas, and the sputtering gas pressure is increased, thereby colliding with the substrate surface. The speed of the recording film source atoms or molecules is reduced. Therefore, the rapid cooling degree of the recording film raw material is reduced, and the produced phase change recording film is in an amorphous state having appropriate stability. Also, according to the present invention, so as to be in contact with the phase change recording film, YuiA crystallization inducing layer is provided. Therefore, generation of crystal nuclei is promoted at the interface between the phase change recording film and the crystallization inducing layer. Therefore, according to the present invention, a non-initialization type phase change optical recording medium capable of overwriting recording immediately after manufacture without requiring initial crystallization of the recording film.BodyA novel phase change optical recording medium manufacturing method that can be realized is provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing an uninitialized phase change optical recording medium according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view schematically showing an uninitialized phase change optical recording medium according to another embodiment of the present invention.
FIG. 3 is a cross-sectional view schematically showing an uninitialized phase change optical recording medium according to still another embodiment of the present invention.
FIG. 4 is a cross-sectional view schematically showing an uninitialized phase change optical recording medium according to still another embodiment of the present invention.
FIG. 5 is a diagram schematically showing a sputtering apparatus used for manufacturing a phase change optical recording medium according to an embodiment of the present invention.
FIG. 6 is a diagram schematically showing an optical disk drive device used in an embodiment of the present invention.
FIG. 7 is a graph showing the laser beam power necessary for recording / erasing / reproducing information in the phase-change optical recording medium according to the embodiment of the present invention.
[Explanation of symbols]
1-1 to 1-4: Phase change optical recording medium
2 ... Board
3 ... Translucent interference layer
4-n ... Dielectric film
5. Phase change recording film
6 ... Metal reflection layer
7 ... Protective film
8-1, 8-2 ... Crystallization inducing layer
9 ... Base
10-n, 11 ... Valve
12 ... Vacuum turbo pump
13-n ... Target
14-n ... electrode
15-n ... Shutter
16 ... RF power supply
17 ... changeover switch
21 ... Chamber
32 ... Spindle motor
33 ... Optical head
34 ... Linear motor
35. Modulation circuit
36 ... Input device
37 ... Laser driver
38 ... Preamplifier
39 ... binarization circuit
40. Demodulator circuit
41 ... Output device
43-46 ... control system

Claims (2)

A phase change recording film that reversibly changes phase between crystalline and amorphous upon irradiation with a light beam, and a crystallization-inducing layer disposed in contact with the phase change recording film. A method for producing an initialization type phase change optical recording medium, comprising:
The phase change recording film is formed by vacuum sputtering using a Kr gas or a Xe gas as a sputtering gas under a sputtering gas pressure of 5 × 10 ⁻² torr or more,
A non-initializing type characterized in that a ZnS / SiO ₂ film is formed as the crystallization-inducing layer , an Ar gas is used as a sputtering gas, and a vacuum sputtering method is used under a sputtering gas pressure of 5 × 10 ⁻⁴ torr or less. A method of manufacturing a phase change optical recording medium. A phase change recording film that reversibly changes phase between crystalline and amorphous upon irradiation with a light beam, and a crystallization-inducing layer disposed in contact with the phase change recording film. A method for producing an initialization type phase change optical recording medium, comprising:
The phase change recording film is formed by vacuum sputtering using a Kr gas or a Xe gas as a sputtering gas under a sputtering gas pressure of 5 × 10 ⁻² torr or more,
As the crystallization-inducing layer, the GeN film, using Ar gas as a sputtering gas, the production of non-initialized phase-change optical recording medium, characterized by forming a film by vacuum sputtering while supplying N ₂ gas Method.

Images