JP3772972B2 - Silver alloy sputtering target for reflection layer formation of optical recording media - Google Patents
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Description
【０００１】
【発明の属する技術分野】
この発明は、半導体レーザーなどのレーザービームを用いて音声、映像、文字などの情報信号を再生あるいは記録・再生・消去を行う光記録ディスク（ＣＤ−ＲＷ，ＤＶＤ−ＲＡＭ）などの光記録媒体の構成層である半透明反射層または反射層(以下、両者を含めて反射層と呼ぶ)をスパッタリング法にて形成するための銀合金スパッタリングターゲットに関するものである。
【０００２】
【従来の技術】
従来、光記録ディスク（ＣＤ−ＲＷ，ＤＶＤ−ＲＡＭ）などの光記録媒体の反射層としてＡｇまたはＡｇ合金反射層が使用されており、このＡｇまたはＡｇ合金反射層は４００〜８３０ｎｍの幅広い波長域での反射率が高く、特に光記録媒体の高密度化記録に用いられる短波長のレーザー光に対して反射率が大きいので好適であるとされている。
前記ＡｇまたはＡｇ合金反射層の形成には、ＡｇまたはＡｇ−Ｓｎ合金からなるターゲットをスパッタすることにより形成されることが知られている（特開２００１−３５０１４号公報参照）。
【０００３】
【発明が解決しようとする課題】
しかし、光記録媒体の中でも記録層に相変化記録材料を用い、繰り返し記録・再生・消去を行う光記録媒体においては、記録・再生・消去の繰り返し回数が増大するにつれて、ＡｇまたはＡｇ−Ｓｎ合金反射層の反射率が低下し、長期に亘る十分な記録再生耐性が得られなかった。
この原因の一つとして光記録媒体に繰り返し記録・再生・消去を行うと、レーザー光の照射によりＡｇ反射層の加熱冷却が繰り返され、それによってＡｇ反射層が再結晶化し、結晶粒が粗大化することによって反射率が低下することを突き止めた。
【０００４】
【課題を解決するための手段】
そこで本発明者らは、記録・再生・消去の繰り返し回数が増大しても反射層の反射率が低下することの少ないＡｇ合金反射層を得るべく研究を行った。その結果、
（イ）ＡｇにＳｎ：１〜１１質量％を添加したＡｇ−Ｓｎ合金にＣａ，Ｂｅ，Ｓｉから選ばれる１種または２種以上の合計：０．００５〜０．０５質量％を含有せしめた組成の銀合金ターゲットを用いてスパッタリングすることにより得られた銀合金反射層は、従来のＡｇまたはＡｇ−Ｓｎ合金からなるターゲットを用いてスパッタすることにより得られた銀または銀合金反射層に比べて、レーザービームの繰り返し照射に伴う繰り返し加熱冷却を受けても結晶粒が粗大化することが少なく、したがって、長期間使用しても反射率の低下が極めて少ない、
（ロ）ＡｇにＳｎ：１〜１１質量％を添加したＡｇ−Ｓｎ合金にＤｙ，Ｌａ，Ｎｄ，Ｔｂ，Ｇｄから選ばれる１種または２種以上の合計：０．１〜３質量％を含有させた組成の銀合金ターゲットを用いてスパッタリングすることにより得られた銀合金反射層は、従来のＡｇまたはＡｇ−Ｓｎ合金からなるターゲットを用いてスパッタすることにより得られた銀または銀合金反射層に比べて、レーザービームの繰り返し照射に伴う繰り返し加熱冷却を受けても結晶粒が粗大化することが少なく、したがって、長期間使用しても反射率の低下が極めて少ない、
（ハ）ＡｇにＳｎ：１〜１１質量％を添加したＡｇ−Ｓｎ合金に、さらにＣａ，Ｂｅ，Ｓｉから選ばれる１種または２種以上の合計：０．００５〜０．０５質量％とＤｙ，Ｌａ，Ｎｄ，Ｔｂ，Ｇｄから選ばれる１種または２種以上の合計：０．１〜３質量％とを共に含有せしめた銀合金ターゲットを用いてスパッタリングすることにより得られた銀合金反射層でも同じ効果が得られる、
という研究結果が得られたのである。
【０００５】
この発明は、かかる研究結果に基づいて成されたものであって、
（１）Ｓｎ：１〜１１質量％を含有し、さらにＣａ，Ｂｅ，Ｓｉから選ばれる１種または２種以上の合計：０．００５〜０．０５質量％を含有し、残部がＡｇである組成の銀合金からなる光記録媒体の反射層形成用銀合金スパッタリングターゲット、
（２）Ｓｎ：１〜１１質量％を含有し、さらにＤｙ，Ｌａ，Ｎｄ，Ｔｂ，Ｇｄから選ばれる１種または２種以上の合計：０．１〜３質量％を含有し、残部がＡｇである組成の銀合金からなる光記録媒体の反射層形成用銀合金スパッタリングターゲット、
（３）Ｓｎ：１〜１１質量％を含有し、さらにＣａ，Ｂｅ，Ｓｉから選ばれる１種または２種以上の合計：０．００５〜０．０５質量％を含有し、さらにＤｙ，Ｌａ，Ｎｄ，Ｔｂ，Ｇｄから選ばれる１種または２種以上の合計：０．１〜３質量％を含有し、残部がＡｇである組成の銀合金からなる光記録媒体の反射層形成用銀合金スパッタリングターゲット、
に特徴を有するものである。
【０００６】
この発明の銀合金反射層を形成するためのスパッタリングターゲットは、原料としていずれも純度：９９.９９質量％以上の高純度Ａｇおよび高純度Ｓｎ、並びに純度：９９.９質量％以上のＤｙ，Ｌａ，Ｎｄ，ＴｂおよびＧｄを用意し、これら原料を高真空または不活性ガス雰囲気中で溶解し、得られた溶湯を真空または不活性ガス雰囲気中で鋳造してインゴットを作製し、これらインゴットを熱間加工したのち機械加工することにより製造することができる。
【０００７】
Ａｇへの固溶が殆どないＣａ，ＢｅおよびＳｉについては、それぞれの各元素の濃度が０.２０質量％となるようにＡｇを配合した後、高周波真空溶解にて溶解し、溶解後炉内圧力が大気圧となるまでＡｒガスを充填したのち黒鉛製鋳型に鋳造してＣａ，ＢｅおよびＳｉを含むＡｇの母合金を作製し、この母合金をＳｎとともにＡｇに添加して溶解し鋳造することによりインゴットを作製し、得られたインゴットを熱間加工したのち機械加工することにより製造することができる。
【０００８】
次に、この発明のＡｇ合金からなる反射層およびこのＡｇ合金からなる反射層を形成するためのスパッタリングターゲットにおける成分組成を前記の如く限定した理由を説明する。
【０００９】
Ｓｎ：
Ｓｎは、Ａｇに固溶して結晶粒の強度を高め、結晶粒の再結晶粒化を防止し、スパッタにより形成された反射層の反射率の低下を抑制する効果があるが、Ｓｎを１質量％未満含んでも十分な結晶粒の再結晶粒化を防止することができないので反射層の反射率の低下を抑止することができず、一方、Ｓｎが１１質量％を越えて含有すると、スパッタにより形成されたＡｇ合金反射層の内部応力が大きくなり、ターゲットの製造時に結晶粒内および／または結晶粒界に金属間化合物を形成し、割れが生じやすくなるので好ましくない。したがって、Ａｇ合金反射層およびこのＡｇ合金反射層を形成するためのスパッタリングターゲットに含まれるこれらＳｎの含有量は１〜１１質量％(一層好ましくは３〜７質量％)に定めた。
【００１０】
Ｃａ，Ｂｅ，Ｓｉ：
これら成分は、Ａｇに殆ど固溶せず、結晶粒界に析出することにより結晶粒同士の結合を防止し、Ａｇ合金反射層の再結晶化防止をさらに促進する成分であるが、これら成分の１種または２種以上を合計で０．００５質量％未満含んでも格段の効果が得られず、一方、これら成分の１種または２種以上を合計で０．０５質量％を越えて含有すると、ターゲットが著しく硬化し、ターゲットの作製が困難になるので好ましくない。したがって、Ａｇ合金反射層およびこのＡｇ合金反射層を形成するためのスパッタリングターゲットに含まれるこれら成分の含有量は０.００５〜０．０５質量％(一層好ましくは０．０１０〜０．０３５質量％)に定めた。
【００１１】
Ｄｙ，Ｌａ，Ｎｄ，Ｔｂ，Ｇｄ：
これら成分は、Ａｇとの反応により金属間化合物を結晶粒界に形成して結晶粒同士の結合を防止し、Ａｇ合金反射層の再結晶化防止をさらに促進する成分であるが、これら成分の内の１種または２種以上を合計で０．１質量％未満含んでも格段の効果が得られず、一方、これら成分の１種または２種以上を合計で３質量％を越えて含有すると、ターゲットが著しく硬化し、ターゲットの作製が困難になるので好ましくない。したがって、Ａｇ合金反射層およびこのＡｇ合金反射層を形成するためのスパッタリングターゲットに含まれるこれら成分の含有量は０．１〜３質量％(一層好ましくは０．２〜１．５質量％)に定めた。
【００１２】
【発明の実施の形態】
実施例１
原料として純度：９９.９９質量％以上の高純度Ａｇおよび高純度Ｓｎ、並びに純度：９９.９質量％以上のＣａ，ＢｅおよびＳｉを用意した。Ｃａ，ＢｅおよびＳｉはＡｇへの固溶が殆どないので、それぞれの各元素の濃度が０.２０質量％となるようにＡｇを配合した後、高周波真空溶解炉にて溶解し、溶解後炉内圧力が大気圧となるまでＡｒガスを充填したのち黒鉛製鋳型に鋳造することにより予めＣａ，ＢｅおよびＳｉを含むＡｇの母合金を作製した。
この母合金をＳｎと共にＡｇに添加して溶解し鋳造することによりインゴットを作製し、得られたインゴットを６００℃、２時間加熱した後、圧延し、次いで機械加工することにより直径：１２５ｍｍ、厚さ：５ｍｍの寸法を有し、表１〜２に示される成分組成を有する本発明ターゲット１〜１８、比較ターゲット１〜４および従来ターゲット１〜２を製造した。
【００１３】
これら本発明ターゲット１〜９、比較ターゲット１〜４および従来ターゲット１〜２をそれぞれ無酸素銅製のバッキングプレートにはんだ付けし、これを直流マグネトロンスパッタ装置に装着し、真空排気装置にて直流マグネトロンスパッタ装置内を１×１０-4Ｐａまで排気した後、Ａｒガスを導入して１．０Ｐａのスパッタガス圧とし、続いて直流電源にてターゲットに１００Ｗの直流スパッタ電力を印加し、前記ターゲットに対抗しかつ７０ｍｍの間隔を設けてターゲットと平行に配置した直径：３０ｍｍ、厚さ：０．５ｍｍのガラス基板と前記ターゲットの間にプラズマを発生させ、厚さ：１００ｎｍのＡｇおよびＡｇ合金反射膜を形成した。
【００１４】
このようにして形成したＡｇおよびＡｇ合金反射膜の成膜直後の反射率を分光光度計により測定した。その後、形成したＡｇおよびＡｇ合金反射膜を温度：８０℃、相対湿度：８５％の恒温恒湿槽にて２００時間保持したのち、再度同じ条件で反射率を測定した。得られた反射率データから、波長：４００ｎｍおよび６５０ｎｍにおける各反射率を求め、その結果を表１〜２に示して光記録媒体の反射膜として記録再生耐性を評価した。
【００１５】
【表１】
【表２】
表１〜２に示される結果から、この発明の本発明ターゲット１〜１８を用いてスパッタリングを行うことにより得られた反射層は、従来ターゲット１〜２を用いてスパッタリングを行うことにより得られた反射層に比べて、温度：８０℃、相対湿度：８５％の恒温恒湿槽にて２００時間保持後の反射率の低下が少ないことがわかる。しかし、この発明の範囲から外れてＺｎ、Ｃａ，ＢｅおよびＳｉを多く含む比較ターゲット１〜４は、割れが発生したり、硬くなって成形できなくなることが分かる。
【００１８】
実施例２
原料として純度：９９.９９質量％以上の高純度ＡｇおよびＳｎを用意し、さらに純度：９９.９質量％以上のＤｙ，Ｌａ，Ｎｄ，ＴｂおよびＧｄを用意し、これら原料を高周波真空溶解炉で溶解し、得られた溶湯をＡｒガス雰囲気中で黒鉛鋳型に鋳造してインゴットを作製し、得られたインゴットを６００℃、２時間加熱した後、圧延し、次いで機械加工することにより直径：１２５ｍｍ、厚さ：５ｍｍの寸法を有し、表３〜５に示される成分組成を有する本発明ターゲット１９〜４２および比較ターゲット５〜１０を製造した。
【００１９】
これら本発明ターゲット１９〜４２および較ターゲット５〜１０をそれぞれ無酸素銅製のバッキングプレートにはんだ付けし、これを直流マグネトロンスパッタ装置に装着し、真空排気装置にて直流マグネトロンスパッタ装置内を１×１０-4Ｐａまで排気した後、Ａｒガスを導入して１．０Ｐａのスパッタガス圧とし、続いて直流電源にてターゲットに１００Ｗの直流スパッタ電力を印加し、前記ターゲットに対抗しかつ７０ｍｍの間隔を設けてターゲットと平行に配置した直径：３０ｍｍ、厚さ：０．５ｍｍのガラス基板と前記ターゲットの間にプラズマを発生させ、厚さ：１００ｎｍのＡｇ合金反射膜を形成した。
【００２０】
このようにして形成した各Ａｇ合金反射膜の成膜直後の反射率を分光光度計により測定した。その後、形成した各Ａｇ合金反射膜を温度：８０℃、相対湿度：８５％の恒温恒湿槽にて２００時間保持したのち、再度同じ条件で反射率を測定した。得られた反射率データから、波長：４００ｎｍおよび６５０ｎｍにおける各反射率を求め、その結果を表３〜５に示して光記録媒体の反射膜として記録再生耐性を評価した。
【００２１】
【表３】
【表４】
【表５】
表３〜５に示される結果から、この発明の本発明ターゲット１９〜４２を用いてスパッタリングを行うことにより得られた反射層は、表２に示される従来ターゲット１〜２を用いてスパッタリングを行うことにより得られた反射層に比べて、温度：８０℃、相対湿度：８５％の恒温恒湿槽にて２００時間保持後の反射率の低下が少ないことがわかる。しかし、比較ターゲット５〜１０に見られるように、Ｄｙ，Ｌａ，Ｎｄ，ＴｂおよびＧｄの合計が３質量％より多く含有すると、圧延中に割れが発生するなどして成形できなくなることが分かる。
【００２５】
実施例３
実施例１で用意した高純度Ａｇおよび高純度Ｓｎ、Ｃａ，ＢｅおよびＳｉを含む母合金、並びに実施例２で用意したＤｙ，Ｌａ，Ｎｄ，ＴｂおよびＧｄを用いて表６に示される成分組成を有する本発明ターゲット４３〜５４を作製し、これらターゲットについて実施例１と同様にしてガラス基板表面に厚さ：１００ｎｍのＡｇ合金反射膜を形成し、各Ａｇ合金反射膜の成膜直後の反射率を分光光度計により測定した。その後、形成した各Ａｇ合金反射膜を温度：８０℃、相対湿度：８５％の恒温恒湿槽にて２００時間保持したのち、再度同じ条件で反射率を測定した。得られた反射率データから、波長：４００ｎｍおよび６５０ｎｍにおける各反射率を求め、その結果を表６に示して光記録媒体の反射膜として記録再生耐性を評価した。
【００２６】
【表６】
表６に示される結果から、この発明の本発明ターゲット４３〜５４を用いてスパッタリングを行うことにより得られた反射層は表２の従来ターゲット１〜２を用いてスパッタリングを行うことにより得られた反射層に比べて、波長：４００ｎｍおよび６５０ｎｍにおける温度：８０℃、相対湿度：８５％の恒温恒湿槽にて２００時間保持後の反射率の低下が少ないことがわかる。
【００２８】
【発明の効果】
上述のように、この発明の光記録媒体の反射層形成用銀合金スパッタリングターゲットを用いて作製した反射層は、従来の光記録媒体の反射層形成用銀合金スパッタリングターゲットを用いて作製した反射層に比べて、経時変化による反射率の低下が少なく、長期にわたって使用できる光記録媒体を製造することができ、メディア産業の発展に大いに貢献し得るものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical recording medium such as an optical recording disk (CD-RW, DVD-RAM) for reproducing or recording / reproducing / erasing information signals such as audio, video and characters using a laser beam such as a semiconductor laser. The present invention relates to a silver alloy sputtering target for forming a translucent reflective layer or a reflective layer (hereinafter referred to as a reflective layer together) as a constituent layer by a sputtering method.
[0002]
[Prior art]
Conventionally, an Ag or Ag alloy reflective layer has been used as a reflective layer of an optical recording medium such as an optical recording disk (CD-RW, DVD-RAM), and this Ag or Ag alloy reflective layer has a wide wavelength range of 400 to 830 nm. In particular, it has a high reflectivity, and is particularly suitable for a short wavelength laser beam used for high density recording of an optical recording medium.
It is known that the Ag or Ag alloy reflective layer is formed by sputtering a target made of Ag or an Ag—Sn alloy (see JP 2001-35014 A).
[0003]
[Problems to be solved by the invention]
However, among optical recording media, an optical recording medium that uses a phase change recording material for the recording layer and performs repeated recording / reproducing / erasing, Ag or Ag—Sn alloy as the number of repeated recording / reproducing / erasing increases. The reflectivity of the reflective layer was lowered, and sufficient recording / reproduction durability over a long period of time could not be obtained.
As one of the causes, when recording / reproducing / erasing is repeatedly performed on the optical recording medium, the heating and cooling of the Ag reflecting layer are repeated by irradiation with the laser beam, thereby recrystallizing the Ag reflecting layer and coarsening the crystal grains. As a result, it was found that the reflectance was lowered.
[0004]
[Means for Solving the Problems]
Therefore, the present inventors have studied to obtain an Ag alloy reflective layer in which the reflectance of the reflective layer is less likely to decrease even if the number of recording / reproducing / erasing repetitions is increased. as a result,
(A) Ag—Sn alloy in which Sn: 1 to 11% by mass was added to Ag was mixed with one or more selected from Ca, Be, Si: 0.005 to 0.05% by mass. A silver alloy reflective layer obtained by sputtering using a silver alloy target having a composition is compared with a silver or silver alloy reflective layer obtained by sputtering using a target made of a conventional Ag or Ag-Sn alloy. Thus, even when subjected to repeated heating and cooling accompanying repeated irradiation of the laser beam, the crystal grains are less likely to be coarsened, and therefore, the reflectance is extremely low even after long-term use.
(B) Ag—Sn alloy with Sn: 1 to 11% by mass added to Ag contains one or more selected from Dy, La, Nd, Tb, Gd: 0.1 to 3% by mass in total A silver alloy reflective layer obtained by sputtering using a silver alloy target having the composition described above is obtained by sputtering using a target made of a conventional Ag or Ag-Sn alloy. In comparison, the crystal grains are less likely to become coarse even when subjected to repeated heating and cooling associated with repeated irradiation of the laser beam, and therefore the decrease in reflectance is extremely small even when used for a long period of time.
(C) Ag—Sn alloy in which Sn: 1 to 11 mass% is added to Ag, and one or more selected from Ca, Be, and Si: 0.005 to 0.05 mass% and Dy , La, Nd, Tb, Gd, a silver alloy reflective layer obtained by sputtering using a silver alloy target containing one or more totals of 0.1 to 3% by mass But you can get the same effect,
The research result was obtained.
[0005]
The present invention has been made based on such research results,
(1) Sn: 1 to 11% by mass, and one or more selected from Ca, Be, Si: 0.005 to 0.05% by mass, with the balance being Ag A silver alloy sputtering target for forming a reflective layer of an optical recording medium comprising a silver alloy having a composition;
(2) Sn: 1 to 11% by mass, further including one or more selected from Dy, La, Nd, Tb, Gd: 0.1 to 3% by mass, with the balance being Ag A silver alloy sputtering target for forming a reflective layer of an optical recording medium comprising a silver alloy having a composition of
(3) Sn: 1 to 11% by mass, further including one or more selected from Ca, Be, Si: 0.005 to 0.05% by mass, Dy, La, Silver alloy sputtering for forming a reflective layer of an optical recording medium comprising a silver alloy having a composition containing one to two or more selected from Nd, Tb, Gd: 0.1 to 3% by mass and the balance being Ag target,
It has the characteristics.
[0006]
The sputtering target for forming the silver alloy reflective layer of the present invention has high purity Ag and high purity Sn of purity: 99.99% by mass or more as raw materials, and Dy, La of purity: 99.9% by mass or more. , Nd, Tb and Gd are prepared, these raw materials are melted in a high vacuum or an inert gas atmosphere, and the obtained molten metal is cast in a vacuum or an inert gas atmosphere to produce an ingot. It can be manufactured by machining after the intermediate machining.
[0007]
For Ca, Be, and Si, which have almost no solid solution in Ag, Ag is mixed so that the concentration of each element is 0.20% by mass, and then melted by high-frequency vacuum melting. After filling with Ar gas until the pressure reaches atmospheric pressure, it is cast into a graphite mold to produce an Ag mother alloy containing Ca, Be and Si, and this mother alloy is added to Ag together with Sn to be melted and cast. Thus, an ingot can be produced, and the obtained ingot can be hot-worked and then machined.
[0008]
Next, the reason why the component composition in the sputtering layer for forming the reflective layer made of the Ag alloy of the present invention and the reflective layer made of the Ag alloy is limited as described above will be described.
[0009]
Sn:
Sn dissolves in Ag to increase the strength of the crystal grains, prevents recrystallization of the crystal grains, and suppresses the decrease in the reflectance of the reflection layer formed by sputtering. Even if the content is less than 5% by mass, sufficient recrystallization of crystal grains cannot be prevented, so that a reduction in reflectance of the reflective layer cannot be suppressed. On the other hand, if Sn exceeds 11% by mass, sputtering is not possible. The internal stress of the Ag alloy reflective layer formed by the above increases, and an intermetallic compound is formed in the crystal grains and / or the crystal grain boundaries during the production of the target, and cracks are likely to occur. Therefore, the content of these Sn contained in the Ag alloy reflective layer and the sputtering target for forming the Ag alloy reflective layer is set to 1 to 11% by mass (more preferably 3 to 7% by mass).
[0010]
Ca, Be, Si:
These components are components that hardly dissolve in Ag and prevent bonding between crystal grains by precipitating at crystal grain boundaries, and further promote recrystallization prevention of the Ag alloy reflective layer. Even if 1 type or 2 types or more are included in total less than 0.005% by mass, a remarkable effect cannot be obtained. On the other hand, if 1 type or 2 types or more of these components are contained in total exceeding 0.05% by mass, This is not preferable because the target is markedly cured and it becomes difficult to produce the target. Therefore, the content of these components contained in the Ag alloy reflective layer and the sputtering target for forming the Ag alloy reflective layer is 0.005 to 0.05% by mass (more preferably 0.010 to 0.035% by mass). ).
[0011]
Dy, La, Nd, Tb, Gd:
These components are components that form intermetallic compounds at the grain boundaries by reaction with Ag to prevent bonding between the crystal grains, and further promote the prevention of recrystallization of the Ag alloy reflective layer. Even if it contains less than 0.1% by mass of one or more of them, a remarkable effect cannot be obtained. On the other hand, when one or more of these components are contained in excess of 3% by mass, This is not preferable because the target is markedly cured and it becomes difficult to produce the target. Therefore, the content of these components contained in the Ag alloy reflective layer and the sputtering target for forming the Ag alloy reflective layer is 0.1 to 3% by mass (more preferably 0.2 to 1.5% by mass). Determined.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Example 1
As raw materials, high purity Ag and high purity Sn having a purity of 99.99% by mass or more, and Ca, Be and Si having a purity of 99.9% by mass or more were prepared. Since Ca, Be, and Si have almost no solid solution in Ag, Ag is mixed so that the concentration of each element is 0.20% by mass, and then melted in a high-frequency vacuum melting furnace. A master alloy of Ag containing Ca, Be and Si was prepared in advance by filling with Ar gas until the internal pressure became atmospheric pressure and then casting it into a graphite mold.
The master alloy is added to Ag together with Sn and melted and cast to produce an ingot. The obtained ingot is heated at 600 ° C. for 2 hours, then rolled and then machined to obtain a diameter of 125 mm and a thickness. The present invention targets 1 to 18, comparative targets 1 to 4, and conventional targets 1 to 2 having the dimensions of 5 mm and having the composition shown in Tables 1 and 2 were manufactured.
[0013]
The present invention targets 1 to 9, comparative targets 1 to 4, and conventional targets 1 to 2 are each soldered to an oxygen-free copper backing plate, and this is mounted on a DC magnetron sputtering device, and DC magnetron sputtering is performed by a vacuum exhaust device. After evacuating the inside of the apparatus to 1 × 10 −4 Pa, Ar gas is introduced to a sputtering gas pressure of 1.0 Pa, and then 100 W DC sputtering power is applied to the target by a DC power source to counter the target. In addition, plasma is generated between a glass substrate having a diameter of 30 mm and a thickness of 0.5 mm arranged parallel to the target with an interval of 70 mm and the target, and Ag and Ag alloy reflecting film having a thickness of 100 nm are formed. Formed.
[0014]
The reflectance immediately after deposition of the thus formed Ag and Ag alloy reflecting film was measured with a spectrophotometer. Thereafter, the formed Ag and Ag alloy reflective film was held in a constant temperature and humidity chamber at a temperature of 80 ° C. and a relative humidity of 85% for 200 hours, and then the reflectance was measured again under the same conditions. Respective reflectances at wavelengths of 400 nm and 650 nm were obtained from the obtained reflectance data, and the results are shown in Tables 1 and 2 to evaluate recording / reproducing resistance as a reflective film of an optical recording medium.
[0015]
[Table 1]
[Table 2]
From the results shown in Tables 1-2, the reflective layer obtained by performing sputtering using the present invention targets 1-18 of the present invention was obtained by performing sputtering using conventional targets 1-2. Compared with the reflective layer, it can be seen that there is little decrease in reflectance after holding for 200 hours in a constant temperature and humidity chamber of temperature: 80 ° C. and relative humidity: 85%. However, it is understood that the comparative targets 1 to 4 that are out of the scope of the present invention and contain a large amount of Zn, Ca, Be, and Si are cracked or hard and cannot be molded.
[0018]
Example 2
High purity Ag and Sn having a purity of 99.99% by mass or more are prepared as raw materials, and Dy, La, Nd, Tb and Gd having a purity of 99.9% by mass or more are prepared. The resulting molten metal was cast into a graphite mold in an Ar gas atmosphere to produce an ingot. The obtained ingot was heated at 600 ° C. for 2 hours, then rolled and then machined to obtain a diameter: The present invention targets 19 to 42 and comparative targets 5 to 10 having the dimensions of 125 mm and thickness: 5 mm and having the composition shown in Tables 3 to 5 were manufactured.
[0019]
These targets 19 to 42 and comparison targets 5 to 10 of the present invention are each soldered to a backing plate made of oxygen-free copper, and this is mounted on a DC magnetron sputtering apparatus. After exhausting to -4 Pa, Ar gas was introduced to a sputtering gas pressure of 1.0 Pa, and then 100 W of DC sputtering power was applied to the target with a DC power source, and the target was opposed to a distance of 70 mm. Plasma was generated between a glass substrate having a diameter of 30 mm and a thickness of 0.5 mm that was provided and arranged in parallel with the target, and an Ag alloy reflective film having a thickness of 100 nm was formed.
[0020]
The reflectance immediately after film formation of each Ag alloy reflective film thus formed was measured with a spectrophotometer. Thereafter, each formed Ag alloy reflective film was held in a constant temperature and humidity chamber at a temperature of 80 ° C. and a relative humidity of 85% for 200 hours, and then the reflectance was measured again under the same conditions. Respective reflectances at wavelengths of 400 nm and 650 nm were obtained from the obtained reflectance data, and the results are shown in Tables 3 to 5 to evaluate recording / reproduction resistance as a reflective film of an optical recording medium.
[0021]
[Table 3]
[Table 4]
[Table 5]
From the results shown in Tables 3 to 5, the reflective layer obtained by performing sputtering using the present invention targets 19 to 42 of the present invention performs sputtering using the conventional targets 1 to 2 shown in Table 2. Compared with the reflective layer obtained by this, it turns out that the fall of the reflectance after holding | maintaining for 200 hours in a constant temperature and humidity chamber of temperature: 80 degreeC and relative humidity: 85% is few. However, as seen in Comparative Targets 5 to 10, when the total of Dy, La, Nd, Tb, and Gd is more than 3% by mass, it can be seen that molding cannot be performed due to cracking during rolling.
[0025]
Example 3
Component compositions shown in Table 6 using the high purity Ag and the master alloy containing high purity Sn, Ca, Be and Si prepared in Example 1 and Dy, La, Nd, Tb and Gd prepared in Example 2 Inventive targets 43 to 54 having a thickness of 100 nm were prepared, an Ag alloy reflective film having a thickness of 100 nm was formed on the glass substrate surface in the same manner as in Example 1, and reflection immediately after the formation of each Ag alloy reflective film. The rate was measured with a spectrophotometer. Thereafter, each formed Ag alloy reflective film was held in a constant temperature and humidity chamber at a temperature of 80 ° C. and a relative humidity of 85% for 200 hours, and then the reflectance was measured again under the same conditions. Respective reflectances at wavelengths of 400 nm and 650 nm were obtained from the obtained reflectance data, and the results are shown in Table 6 to evaluate recording / reproduction resistance as a reflective film of an optical recording medium.
[0026]
[Table 6]
From the results shown in Table 6, the reflective layer obtained by performing sputtering using the present invention targets 43 to 54 of the present invention was obtained by performing sputtering using the conventional targets 1 and 2 in Table 2. Compared to the reflective layer, it can be seen that there is little decrease in reflectivity after holding for 200 hours in a constant temperature and humidity chamber at wavelengths of 400 nm and 650 nm: 80 ° C. and relative humidity: 85%.
[0028]
【The invention's effect】
As described above, the reflective layer produced using the silver alloy sputtering target for forming the reflective layer of the optical recording medium of the present invention is the reflective layer produced using the silver alloy sputtering target for forming the reflective layer of the conventional optical recording medium. As compared with the above, it is possible to manufacture an optical recording medium that can be used over a long period of time with less decrease in reflectance due to changes with time, and can greatly contribute to the development of the media industry.
Claims (4)
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7514037B2 (en) | 2002-08-08 | 2009-04-07 | Kobe Steel, Ltd. | AG base alloy thin film and sputtering target for forming AG base alloy thin film |
| JP2005029849A (en) | 2003-07-07 | 2005-02-03 | Kobe Steel Ltd | Ag ALLOY REFLECTIVE FILM FOR REFLECTOR, REFLECTOR USING THE Ag ALLOY REFLECTIVE FILM, AND Ag ALLOY SPUTTERING TARGET FOR DEPOSITING THE Ag ALLOY REFLECTIVE FILM |
| JP3907666B2 (en) | 2004-07-15 | 2007-04-18 | 株式会社神戸製鋼所 | Read-only optical information recording medium for laser marking |
| JP2006294195A (en) | 2005-04-14 | 2006-10-26 | Kobe Steel Ltd | Ag alloy reflection film for optical information recording, optical information recording medium and ag alloy sputtering target for deposition of ag alloy reflection film for optical information recording |
| JP4377861B2 (en) | 2005-07-22 | 2009-12-02 | 株式会社神戸製鋼所 | Ag alloy reflecting film for optical information recording medium, optical information recording medium, and Ag alloy sputtering target for forming Ag alloy reflecting film for optical information recording medium |
| JP4527624B2 (en) | 2005-07-22 | 2010-08-18 | 株式会社神戸製鋼所 | Optical information medium having Ag alloy reflective film |
| JP2007035104A (en) | 2005-07-22 | 2007-02-08 | Kobe Steel Ltd | Ag ALLOY REFLECTION FILM FOR OPTICAL INFORMATION RECORDING MEDIUM, OPTICAL INFORMATION RECORDING MEDIUM AND Ag ALLOY SPUTTERING TARGET FOR FORMING Ag ALLOY REFLECTION FILM FOR OPTICAL INFORMATION RECORDING MEDIUM |
| JP4377877B2 (en) | 2005-12-21 | 2009-12-02 | ソニー株式会社 | Ag alloy reflecting film for optical information recording medium, optical information recording medium, and Ag alloy sputtering target for forming Ag alloy reflecting film for optical information recording medium |
| JP2007335061A (en) | 2006-05-16 | 2007-12-27 | Sony Corp | Optical information recording medium and its burst cutting area marking method |
| WO2008026601A1 (en) | 2006-08-28 | 2008-03-06 | Kabushiki Kaisha Kobe Seiko Sho | Ag ALLOY REFLECTION FILM FOR OPTICAL INFORMATION RECORDING MEDIUM, OPTICAL INFORMATION RECORDING MEDIUM, AND SPUTTERING TARGET FOR Ag ALLOY REFLECTION FILM FOR OPTICAL INFORMATION RECORDING MEDIUM FORMATION |
| JP4833942B2 (en) | 2007-08-29 | 2011-12-07 | 株式会社コベルコ科研 | Ag-based alloy sputtering target |
| JP2009076129A (en) | 2007-09-19 | 2009-04-09 | Kobe Steel Ltd | Read-only optical information recording medium |
| JP5331420B2 (en) | 2008-09-11 | 2013-10-30 | 株式会社神戸製鋼所 | Read-only optical information recording medium and sputtering target for forming a transflective film of the optical information recording medium |
| JP2010225572A (en) | 2008-11-10 | 2010-10-07 | Kobe Steel Ltd | Reflective anode and wiring film for organic el display device |
| TW201112244A (en) | 2009-04-14 | 2011-04-01 | Kobe Steel Ltd | Optical information recording medium and sputtering target |
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