JP4105956B2 - Light reflection film, liquid crystal display device using the same, and sputtering target for light reflection film - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、例えば反射型液晶表示素子等に使用され、背面において、室内光や自然光等を反射して光源とするための光反射膜に関する。
【０００２】
【従来の技術】
液晶表示素子には反射型と透過型とがあるが、透過型液晶表示素子では光源としてランプを内蔵する必要があり、このランプの消費電力が大きい等の問題から、最近では、ランプを内蔵する必要がないため消費電力の少ない反射型液晶表示素子が注目されている。
【０００３】
この反射型液晶表示素子には、ＴＦＴ液晶パネルの液晶層背面に反射（金属）電極として、またはＳＴＮ液晶パネルの透明電極背面に反射板として光反射膜が必須的に設けられ、室内光や自然光等を反射して画面形成のための光源とされる。このため、光反射膜の反射率が高ければ高いほどより明るくて見やすい画面が形成される。
【０００４】
従来は、この光反射膜として、反射率の高いＡｌの薄膜が用いられてきたが、最近ではより反射率が高く、化学的な腐食にも強いＡｇ主体の薄膜（Ａｇ薄膜）が光反射膜として用いられるようになってきた。
【０００５】
しかし、Ａｇ薄膜は、液晶表示素子の製造の際に高温下で長時間空気中に曝された場合や、製造後の使用の際において高温高湿下で長時間曝された場合等に結晶粒の粗大化、Ａｇ原子の凝集、Ａｇの酸化等に起因する白濁や白点が発生し、反射率が低下してしまうことからＡｇ本来の高い反射率が得られないという問題があった。さらには、素子製造中の不可避的な熱履歴（〜２００℃）により、結晶粒の成長やＡｇ原子の凝集に伴う薄膜表面の粗度の増大や異常粒成長により素子形成が困難になるないしは反射率が一層低下するなどの問題があった。
【０００６】
そこで、Ａｇの結晶粒の成長やＡｇ原子の凝集を防止してＡｇ本来の高い光反射率を発揮させ維持する目的でＡｇに異種元素を添加する提案がなされている。
【０００７】
例えば、特許文献１には、銀より酸化されやすい金属、具体的にはマグネシウム、アルミニウム、チタン、ジルコニウムおよびハフニウムよりなる群から選択された１種または２種以上の金属を含有する銀合金（Ａｇ基合金）からなる薄膜が開示されている。
【０００８】
また、特許文献２には、銀元素のマイグレーションを防止する異種元素、具体的にはアルミニウム、銅、ニッケル、カドミウム、金、亜鉛、マグネシウムからなる群から選択された１種または２種以上の金属との合金である銀系金属材料（Ａｇ基合金）からなる薄膜が開示されている。
【０００９】
【特許文献１】
特開平７−１３４３００号公報
【特許文献２】
特開平９−２３０８０６号公報
【００１０】
【発明が解決しようとする課題】
しかしながら、上記の先行技術によっても、Ａｇの結晶粒の成長やＡｇ原子の凝集を十分に阻止しえず、Ａｇ本来の高い光反射率を確保することができなかった。
【００１１】
そこで、本発明の目的は、Ａｇの結晶粒の成長やＡｇ原子の凝集を可及的に防止できるＡｇ基合金を見出すことにより、Ａｇ本来の高い光反射率とほぼ同等の高い光反射率を備えた高性能の光反射膜やこの光反射膜を用いた液晶表示素子を提供することにある。
【００１２】
【課題を解決するための手段】
請求項１の発明は、液晶表示素子の反射電極または反射板として用いられる光反射膜であって、Ｂｉを０．０１〜４原子％含有するＡｇ基合金からなることを特徴とする光反射膜である。
【００１３】
請求項２の発明は、前記Ａｇ基合金が、さらに、ＮｄおよびＹよりなる群から選ばれた１種または２種の元素を合計量で０．０１〜２原子％含有するものである請求項１に記載の光反射膜である。
【００１４】
請求項３の発明は、液晶表示素子の反射電極または反射板として用いられる光反射膜であって、Ｓｂを０．０１〜４原子％含有するとともに、ＮｄおよびＹよりなる群から選ばれた１種または２種の元素を合計量で０．０１〜２原子％含有するＡｇ基合金からなることを特徴とする光反射膜である。
【００１５】
請求項４の発明は、前記Ａｇ基合金が、さらに、ＡｕおよびＣｕよりなる群から選ばれた１種または２種の元素を合計量で３原子％以下（０原子％を含まない）含有するものである請求項１〜３のいずれか１項に記載の光反射膜。
【００１６】
請求項５の発明は、請求項１〜４のいずれか１項に記載の光反射膜を備えたことを特徴とする液晶表示素子である。
【００１７】
請求項６の発明は、請求項１〜４のいずれか１項に記載の光反射膜を基板上に形成するために用いられるスパッタリングターゲットであって、Ｂｉ：０．２〜１５原子％およびＳｂ：０．０１〜４原子％よりなる群から選ばれた１種または２種の元素を含有するおよびＳｂ：０．０１〜４原子％よりなる群から選ばれた１種または２種の元素を含有するとともに、当該スパッタリングターゲット中のＢｉ含有量およびＳｂ含有量が下記式（１）を満足するＡｇ基合金からなることを特徴とする光反射膜用スパッタリングターゲットである。
０．０１≦０．０００５０２ｎBi 3＋０．００９８７ｎBi 2＋０．０５５３ｎBi＋ｎSb≦４ ・・・（１）
ここに、ｎBiはスパッタリングターゲット中のＢｉ含有量（原子％）、ｎSbはスパッタリングターゲット中のＳｂ含有量（原子％）を意味する。
【００１８】
【発明の実施の形態】
本発明者らは、液晶表示素子の製造の際に光反射膜が空気中に曝された場合や製造後の使用の際において高温高湿下で長時間曝された場合に起きる現象を促進的に把握するために、温度８０℃、相対湿度９０％という高温高湿下で、Ａｇ単独の光反射膜（膜厚１００ｎｍ）を４８時間放置する環境試験を実施した。この光反射膜の反射率は、環境試験前の反射率（波長６５０ｎｍ）に比べると、環境試験後には７．０％程度低下してしまうことがわかった。この反射率の低下（以下、「反射率の経時低下」という。）の原因は、上記従来技術の説明で述べたように、結晶粒の成長やＡｇ原子の凝集等の要因によるものと考えられる。
【００１９】
そこで、本発明者らは、この反射率の経時低下を防止してＡｇ本来の高反射率を得るには、これらの要因を除去ないしは抑制しうる合金成分を見出すことが重要との考えに基づいて鋭意研究を行った。
【００２０】
研究の結果、本発明者らは、Ａｇに、Ｂｉおよび／またはＳｂ（ＢｉおよびＳｂよりなる群から選ばれた１種または２種の元素）を含有させることによって、Ａｇ本来の高反射率を維持しながら、Ａｇの凝集や結晶粒成長を抑制し、反射率の経時低下を抑制できることを見出し、本発明を完成するに至った。
【００２１】
従来から、光反射膜として純ＡｇだけではなくＡｇ基合金を使用する検討が行われているが、本発明で規定するように、ＡｇにＢｉやＳｂを添加し、Ａｇ原子の凝集やＡｇの結晶粒の成長を抑制しようとする知見は従来技術には認められない。Ａｇ原子の凝集やＡｇの結晶粒成長の抑制については、本発明者らの、希土類元素を添加したＡｇ基合金からなる光反射膜の発明（特願２００２−０１７２９）があるが、本発明におけるＢｉ、Ｓｂを含有するＡｇ基合金からなる光反射膜は、それ以上の反射率と耐久性を有するものである。
【００２２】
本発明では、Ｂｉおよび／またはＳｂを含むＡｇ基合金を光反射膜として用いることで、反射率の経時低下を抑制して高い光反射率を維持するものであるため、従来技術とは明確に区別される技術思想に基づくものである。なお、後述するように、Ｂｉおよび／またはＳｂを含むＡｇ基合金に、コストが低い希土類元素、例えばＮｄやＹを添加した合金を用いることもできる。さらに、耐酸化性を向上させる成分であるＡｕ、Ｃｕ、Ｐｔ、Ｐｄ、Ｒｈを含む三元系または四元系以上の合金を用いることもできる。以下、本発明を詳細に説明する。
【００２３】
本発明では、例えば反射型液晶表示素子等に用いられる光反射膜においては可視光の反射特性が要求される点を考慮して、反射率を波長６５０ｎｍで測定して反射特性を検討した。なお、以下の説明において「初期反射率（％）」は、光反射膜を形成した直後の反射率（％）を意味し、この値の大小は、合金元素の種類と量によって左右される。また、「反射率の経時変化量（％）」は、「環境試験後の反射率（％）−初期反射率（％）」で定義され、この経時変化量（％）がマイナスの場合には、環境試験後の反射率が初期反射率より低下することを意味するものである。
【００２４】
光反射膜がＢｉおよび／またはＳｂを含有するＡｇ基合金で形成されると、Ａｇの結晶粒の成長やＡｇ原子の凝集が抑制される。特にスパッタリング法で形成された薄膜は、原子空孔等の多くの欠陥を含むため、Ａｇ原子が移動・拡散し易く、その結果、Ａｇ原子が凝集するものと考えられるが、Ｂｉ、ＳｂがＡｇの結晶中に存在することによりＡｇ原子の移動・拡散が抑制され、Ａｇの結晶粒成長やＡｇ原子の凝集を抑制するものと考えられる。
【００２５】
Ｂｉおよび／またはＳｂを合計量で０．０１原子％以上添加することにより、Ａｇの結晶粒の成長やＡｇ原子の凝集を抑制する効果が発現する。ただし、これらの元素の添加量の増大とともに初期反射率の低下や電気抵抗率の増大を招くため、Ｂｉおよび／またはＳｂの合計添加量は４原子％以下とすることが好ましい。特に液晶表示素子が反射体と電極の両方の役割を担う場合には、電気抵抗率はできるだけ低くすることが望ましい。すなわち、初期反射率に関しては、Ｂｉおよび／またはＳｂの合計添加量は２原子％以内にすれば、８０％以上の高い初期反射率を維持できる。一方、電気抵抗率に関しては、通常、液晶表示素子の配線膜に用いられるＡｌ合金（Ａｌ−Ｔａ、Ａｌ−Ｎｄなど）の電気抵抗率が５〜１５μΩｃｍ程度であることから、後述の実施例で示すように、Ｂｉ、Ｓｂとも１．８原子％以内にすれば、Ａｌ合金配線と同等の１５μΩｃｍ以下の電気抵抗率が得られる。ただし、Ａｌ合金と同様に液晶表示素子配線膜に用いられるＣｒやＭｏなどの高融点金属材料では、電気抵抗率は〜２００μΩｃｍ程度で使用されていることから、Ｂｉ、Ｓｂの添加量が１．８原子％を超えた場合でも、問題なく使用可能である。したがって、Ｂｉおよび／またはＳｂの合計量のより好ましい上限は２原子％である。
【００２６】
一方、Ａｇの結晶粒成長やＡｇ原子の凝集が起こり易い環境を促進的に再現するための環境試験として、光反射膜を温度８０℃、相対湿度９０％の高温高湿環境下に４８時間放置した場合でも、Ｂｉおよび／またはＳｂが合計量で０．０５原子％以上存在すれば、環境試験前の反射率〔＝初期反射率〕（％）と環境試験後の反射率（％）との差を１％以下に抑えられることから、Ｂｉまたは／およびＳｂの合計量のより好ましい下限は０．０５原子％である。
【００２７】
本発明の光反射膜形成に用いられるＡｇ基合金には、さらに、希土類元素、特にＮｄおよび／またはＹが含まれていてもよい。上記のＢｉやＳｂに比べ効果が小さいものの、ＮｄやＹにもＡｇの耐凝集性を向上する効果があり、かつＮｄやＹはＢｉやＳｂに比べ材料コストが低いため、ＢｉやＳｂの一部と置換すればコストを低減することが可能となるからである。なお、Ｎｄおよび／またはＹの合計添加量は０．０１原子％以上とすることが好ましい。ただし、ＮｄやＹの添加は初期反射率や電気抵抗率の低下を招くことから、その合計量は好ましくは２原子％以下、より好ましくは１原子％以下とする。（なお、ＡｇにＢｉおよび／またはＳｂを添加せずに、Ｎｄおよび／またはＹのみを添加しても、Ａｇの耐凝集性を向上できるが、後記実施例で述べるように耐ＮａＣｌ性が向上しない課題がある。）
【００２８】
また、Ａｕ、Ｃｕ、Ｐｔ、Ｐｄ、Ｒｈなどを耐酸化性の向上を目的として添加してもよい。これらの元素は、Ａｇの凝集を抑制する効果はないが、化学的安定性を増加させる効果があり、反射率の経時低下を抑制する作用を有する。なお、これらの元素は、添加量の増大とともに、特に短波長領域（４００ｎｍ前後）の反射率の低下を招くことから、合計量は好ましくは３原子％以下、より好ましくは２原子％以下とする。
【００２９】
本発明の光反射膜は、Ｂｉおよび／またはＳｂを含有し、必要に応じてＮｄ、Ｙ、もしくはＣｕ、Ａｕ、Ｐｄ、Ｒｈ、Ｐｔを含有し、残部は実質的にＡｇであることが、高い初期反射率を得るために好ましい実施形態であるが、本発明の作用を損なわない範囲であれば、上記成分以外の他の成分を添加してもよい。例えば、Ｚｎ、Ｔｉ、Ｍｇ、Ｎｉ等を化学的腐食や反応防止の観点から添加してもよい。また、Ａｒ、Ｏ2，Ｎ2等のガス成分や、溶解原料であるＡｇ基合金に含まれている不純物も許容される。
【００３０】
本発明の光反射膜は、高い反射率を長時間維持できるため、反射型液晶表示素子に用いるのが好適である。また、本発明の光反射膜は、加熱時の結晶粒成長等の構造変化に対する耐性に優れていることから、製造工程中に通常２００〜３００℃の加熱工程を経る液晶表示素子に特に適している。さらに、この光反射膜は導電性を有しているので、反射型液晶表示素子の反射電極として利用することができる。また、透明電極の背面に反射板として設けてもよい。反射電極として利用する場合の電極基板としては、ガラス基板、プラスチックフィルム基板等、公知のものが利用可能である。反射板の基材も同様のものが利用可能である。さらに、光反射膜と配線膜を兼ねるように用いることもできる。
【００３１】
光反射膜を上記基板または基材上に形成するには、スパッタリング法を用いることが好ましい。ＢｉやＳｂは、化学平衡の状態ではＡｇに対する固溶限が極めて小さいが、スパッタリング法により形成された薄膜では、スパッタリング法固有の気相急冷によって非平衡固溶が可能になるため、その他の薄膜形成法でＡｇ基合金薄膜を形成した場合に比べ、上記合金元素がＡｇマトリックス中に均一に存在しやすい。その結果、Ａｇ基合金の耐酸化性が向上し、かつＡｇ原子の凝集に対する抑制効果が発揮される。
【００３２】
光反射膜の膜厚は５０〜３００ｎｍが好ましい。５０ｎｍより薄い膜では、光が透過し始めるため、反射率が低くなる。一方、３００ｎｍを超えると、反射率に関しては問題ないが、生産性やコスト面で不利となる。
【００３３】
スパッタリングの際には、スパッタリングターゲット（以下、単に「ターゲット」ともいう。）として、Ｂｉ：０．２〜１５原子％およびＳｂ：０．０１〜４原子％よりなる群から選ばれた１種または２種の元素を含有するとともに、当該スパッタリングターゲット中のＢｉ含有量およびＳｂ含有量が下記再掲式（１）を満足するＡｇ基合金を用いることにより、所望の化学組成の光反射膜を得ることができる。
【００３４】
０．０１≦０．０００５０２ｎBi 3＋０．００９８７ｎBi 2＋０．０５５３ｎBi＋ｎSb≦４ ・・・（１）[再掲]
【００３５】
ここで、ターゲット中のＢｉの含有量を光反射膜中のＢｉの含有量より高くする理由は以下のとおりである。すなわち、Ｂｉを含むＡｇ基合金からなるターゲットを用いてスパッタリング法により光反射膜を形成する際、光反射膜中のＢｉ含有量はターゲット中のＢｉ含有量の数％〜数十％に低下することが認められる。この原因としては、ＡｇとＢｉの融点の差が大きいために成膜中に基板上からＢｉが再蒸発すること、Ａｇのスパッタ率がＢｉのスパッタ率に比べて大きいためにＢｉがスパッタされにくいこと、ＢｉがＡｇに比べて酸化されやすいためにターゲット表面でＢｉのみが酸化されてスパッタされないこと、などが考えられる。このように光反射膜中の元素含有量がターゲット中の元素含有量から大幅に低下する現象は、Ａｇ−Ｓｂ合金、Ａｇ−希土類金属合金など他のＡｇ基合金ではみられない現象である。このため、ターゲット中のＢｉ含有量は目標とする光反射膜中のＢｉ含有量より高くする必要がある。例えばＢｉを０．００５〜０．４原子％含む光反射膜を得るためには光反射膜中に取り込まれないＢｉの量を考慮して、ターゲット中のＢｉ含有量を０．１５〜４．５原子％とする必要がある（後述の実施例３参照）。なお、前述のとおり、光反射膜中に含まれるＢｉとＳｂの合計量は０．０１〜４原子％とする必要がある。このため、ターゲット中のＢｉ含有量およびＳｂ含有量は上記数値範囲を満足するとともに、下記再掲式（１）を満足する必要がある。
【００３６】
０．０１≦０．０００５０２ｎBi 3＋０．００９８７ｎBi 2＋０．０５５３ｎBi＋ｎSb≦４ ・・・（１）[再掲]
【００３７】
ここで、上記式(１)中のｎBiに関する各係数の値は、ターゲット中のＢｉ含有量と光反射膜中のＢｉ含有量との相関関係を実験的に調査し、その結果から近似して得られたものである。
【００３８】
ターゲットとしては、溶解・鋳造法で作製したＡｇ基合金（溶製Ａｇ基合金）を使用することが好ましい。溶製Ａｇ基合金は組織的に均一であり、スパッタ率や出射角度を一定にすることができるので、成分組成が均一な光反射膜を得ることができる。上記溶製Ａｇ基合金ターゲットの酸素含有量を１００ｐｐｍ以下に制御すれば、膜形成速度を一定に保持し易くなり、光反射膜中の酸素量も低くなるため、反射率や電気抵抗率が向上する。
【００３９】
本発明の反射型液晶表示素子は、本発明の光反射膜を備えていればよく、その他の液晶表示素子としての構成は特に限定されず、液晶表示素子の分野において公知のあらゆる構成を採用することができる。
【００４０】
【実施例】
以下実施例によって本発明をさらに詳述するが、下記実施例は本発明を制限するものではなく、本発明の趣旨を逸脱しない範囲で変更実施することは、全て本発明に含まれる。
【００４１】
（実施例１）
純Ａｇターゲット上に５ｍｍ×５ｍｍのＢｉまたはＳｂ金属チップを配置し、ＤＣマグネトロンスパッタリングにより、ガラス基板上に厚さ１００ｎｍの表１の試験Ｎｏ．１〜１２に示す成分組成の試料を作成した。薄膜の組成については、別途、同一条件で膜厚１μｍの試料を作製し、ＩＣＰ−質量分析法（セイコーインスツルメンツ社製ＳＰＱ−８０００）を用いて組成の同定を行った。具体的には、１００ｍｇ以上の試料を前処理として硝酸：純水＝１：１の溶液に溶かし、これを２００℃のホットプレート上で加熱して試料が完全に溶解したことを確認した後冷却し、分析を行った。ターゲットサイズはφ１００ｍｍで、ガラス基板のサイズはφ５０ｍｍである。主な成膜条件は、到達真空度：６．６７×１０-4Ｐａ、成膜時のＡｒガス圧：０．２６７Ｐａ、基板温度：２５℃、ターゲット−基板間距離：５５ｍｍである。
【００４２】
成膜後直ちに、各試料の反射率を可視紫外分光光度計（島津製作所製）で測定した。また、これらの試料の環境試験（温度８０℃、相対湿度９０％、時間４８ｈ）後の反射率を上記分光光度計で測定し、環境試験前後の反射率の変化量を評価した。さらに環境試験前後の表面粗度を原子間力顕微鏡（ＡＦＭ）で測定し、環境試験前後の表面粗度の変化量を評価した。さらに塩水浸漬試験（ＮａＣｌ：０．０５ｍｏｌ／Ｌ、１５ｍｉｎ）を行い、目視で光反射膜の変色の程度および基板からの光反射膜の剥離の有無を観察し、耐ＮａＣｌ性を評価した。
【００４３】
（比較例１）
純Ａｇターゲット上に配置する金属チップを、上記実施例１のＢｉまたはＳｂに代えて、Ｎｄ、Ｉｎ、ＮｂまたはＳｎとし、上記実施例１と同じ成膜条件で表１の試験Ｎｏ．１３〜１６に示す組成のＡｇ合金薄膜を作製し、実施例１と同様の評価を行った。
【００４４】
実施例１および比較例１についての評価結果を表１に併せて示す。表１の実施例１に示すように、純Ａｇ薄膜（試験Ｎｏ．１）に比べ、ＢｉまたはＳｂの添加（試験Ｎｏ．２〜１２）により、環境試験前後の反射率の変化量および表面粗度の変化量が顕著に抑制されているのが分かる。ＢｉまたはＳｂの添加量については、０．０１原子％でも効果が認められるが（試験Ｎｏ．２、８）、特に０．０５原子％以上で効果が大きい（試験Ｎｏ．３〜７、９〜１２）。また塩水浸漬試験後においても、ＢｉまたはＳｂの添加により、光反射膜の黄色化などの変色や基板からの光反射膜の剥離がなくなり、良好な耐久性を示すことが分かる。
【００４５】
これに対し、表１の比較例１に示すように、Ａｇ−Ｎｄは、環境試験前後の反射率の変化量の抑制に対しては良好な結果を示すが、ＮａＣｌ耐性がない（試験Ｎｏ．１３）。またＡｇ−Ｉｎ、Ａｇ−Ｎｂ、Ａｇ−Ｓｎでは表面粗度の変化量に対する抑制効果が非常に低い（試験Ｎｏ．１４〜１６）。
【００４６】
（実施例２）
純ＡｇまたはＡｇ−０．２％Ｓｂのターゲット上に、５ｍｍ×５ｍｍのＢｉ、Ｃｕ、Ａｕ、ＮｄまたはＹの金属チップを設置した複合ターゲットを用いて、実施例１と同様の成膜条件で試料を作製した。これらの試料について実施例１と同様の評価を行った結果を表２に示す。なお表２には、比較のため表１中の試験Ｎｏ．１および４を再掲した。
【００４７】
Ａｇ−ＢｉにさらにＮｄまたはＹを添加することにより、表面粗度およびその変化量がさらに改善されることが分かる（試験Ｎｏ．１７、１８）。また、Ａｇ−ＢｉまたはＡｇ−ＳｂにさらにＣｕまたはＡｕを添加した場合には、表面粗度のさらなる改善効果はないものの、反射率の変化量を低減する効果があることが分かる（試験Ｎｏ．１９〜２４）。
【００４８】
【表１】
【表２】
（実施例３）
純ＡｇにＢｉをその添加量を種々変化させて添加し溶製してＡｇ−Ｂｉ合金ターゲットを作製した。このターゲットを用いて実施例１と同様の成膜条件で薄膜を作製した。そして、実施例１と同じＩＣＰ−質量分析法でターゲットおよび薄膜中のＢｉ含有量を測定した。測定結果を表３に示す。表３に示すように、薄膜中のＢｉ含有量はターゲット中のＢｉ含有量の数％〜数十％となり、薄膜中のＢｉ含有量を０．０１〜４原子％とするためには、ターゲット中のＢｉ含有量を０．２〜１５原子％にする必要があることが分かる。
【００５１】
【表３】
【発明の効果】
以上述べたように、本発明によれば、Ａｇ本来の高い光反射率とほぼ同等の高い光反射率を備えた高性能の光反射膜、この光反射膜を用いた液晶表示素子、およびこの光反射膜形成用のスパッタリングターゲットを提供できるようになった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light reflecting film that is used for, for example, a reflective liquid crystal display element and reflects a room light, natural light or the like on the back surface to make a light source.
[0002]
[Prior art]
There are two types of liquid crystal display elements: reflective type and transmissive type. However, it is necessary to incorporate a lamp as a light source in the transmissive liquid crystal display element. Since there is no need, a reflective liquid crystal display element with low power consumption has attracted attention.
[0003]
In this reflection type liquid crystal display element, a light reflection film is indispensably provided as a reflection (metal) electrode on the back surface of the liquid crystal layer of the TFT liquid crystal panel or as a reflection plate on the back surface of the transparent electrode of the STN liquid crystal panel. Etc. is reflected as a light source for screen formation. For this reason, the higher the reflectance of the light reflecting film, the brighter and easier to see a screen is formed.
[0004]
Conventionally, an Al thin film having a high reflectivity has been used as the light reflecting film. Recently, an Ag-based thin film (Ag thin film) having a higher reflectivity and resistant to chemical corrosion is a light reflecting film. It has come to be used as.
[0005]
However, the Ag thin film has crystal grains when it is exposed to the air for a long time at a high temperature during the production of a liquid crystal display element or when it is exposed for a long time under a high temperature and a high humidity during use after production. As a result, white turbidity and white spots due to coarsening of Ag, aggregation of Ag atoms, oxidation of Ag, and the like are generated, and the reflectance is lowered. Therefore, there is a problem that the high reflectance inherent in Ag cannot be obtained. Furthermore, due to inevitable thermal history (up to 200 ° C.) during device manufacture, device formation becomes difficult or reflective due to the increase in roughness of the thin film surface due to the growth of crystal grains and the aggregation of Ag atoms, and abnormal grain growth. There was a problem that the rate was further lowered.
[0006]
Therefore, a proposal has been made to add a different element to Ag for the purpose of preventing the growth of Ag crystal grains and aggregation of Ag atoms and exhibiting and maintaining the high light reflectance inherent in Ag.
[0007]
For example, Patent Document 1 discloses a silver alloy (Ag) containing a metal that is more easily oxidized than silver, specifically, one or more metals selected from the group consisting of magnesium, aluminum, titanium, zirconium, and hafnium. A thin film made of a base alloy is disclosed.
[0008]
Patent Document 2 discloses that one or more metals selected from the group consisting of different elements that prevent migration of silver elements, specifically, aluminum, copper, nickel, cadmium, gold, zinc, and magnesium. A thin film made of a silver-based metal material (Ag-based alloy), which is an alloy of
[0009]
[Patent Document 1]
JP-A-7-134300 [Patent Document 2]
Japanese Patent Laid-Open No. 9-230806
[Problems to be solved by the invention]
However, even with the above prior art, the growth of Ag crystal grains and the aggregation of Ag atoms cannot be sufficiently prevented, and the high light reflectance inherent in Ag cannot be ensured.
[0011]
Therefore, an object of the present invention is to find an Ag-based alloy that can prevent Ag crystal grain growth and Ag atom aggregation as much as possible, thereby achieving a high light reflectivity substantially equal to the original high light reflectivity. An object of the present invention is to provide a high-performance light reflection film provided and a liquid crystal display element using the light reflection film.
[0012]
[Means for Solving the Problems]
The invention of claim 1 is a light reflecting film used as a reflecting electrode or a reflecting plate of a liquid crystal display element, wherein Bi is set to 0 . A light reflecting film comprising an Ag-based alloy containing 01 to 4 atomic%.
[0013]
Claim The invention according to claim 2, wherein the Ag based alloy further, those containing 0.01 to 2 atomic% in a total amount of one or two elements selected from the group consisting of Nd and Y The light reflecting film according to 1.
[0014]
The invention of claim 3 is a light reflecting film used as a reflecting electrode or a reflecting plate of a liquid crystal display element, and contains 0.01 to 4 atomic% of Sb and is selected from the group consisting of Nd and Y A light reflecting film comprising an Ag-based alloy containing 0.01 to 2 atomic% of seeds or two kinds of elements in a total amount .
[0015]
The invention according to claim 4, wherein the Ag based alloy further, (not including 0 atomic%) 3 atomic% or less in a total amount of one or two kinds of elements selected from Au and C u by Li Cheng group The light reflecting film according to claim 1, which is contained.
[0016]
A fifth aspect of the present invention is a liquid crystal display device comprising the light reflecting film according to any one of the first to fourth aspects.
[0017]
Invention of Claim 6 is a sputtering target used in order to form the light reflection film of any one of Claims 1-4 on a board | substrate, Comprising: Bi: 0.2-15 atomic% and Sb : Containing one or two elements selected from the group consisting of 0.01 to 4 atom% and Sb: one or two elements selected from the group consisting of 0.01 to 4 atom% A sputtering target for a light reflecting film, characterized in that it comprises an Ag-based alloy in which the Bi content and the Sb content in the sputtering target satisfy the following formula (1).
0.01 ≦ 0.000502n Bi 3 + 0.00987n Bi 2 + 0.0553n Bi + n Sb ≦ 4 (1)
Here, n Bi means Bi content (atomic%) in the sputtering target, and n Sb means Sb content (atomic%) in the sputtering target.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have promoted a phenomenon that occurs when a light reflecting film is exposed to the air during the production of a liquid crystal display element or when exposed to a high temperature and high humidity for a long time during use after production. Therefore, an environmental test was carried out in which a light reflecting film made of Ag alone (film thickness 100 nm) was allowed to stand for 48 hours at a high temperature and high humidity of 80 ° C. and 90% relative humidity. It has been found that the reflectance of the light reflecting film is reduced by about 7.0% after the environmental test as compared to the reflectance before the environmental test (wavelength 650 nm). The cause of this decrease in reflectivity (hereinafter referred to as “reflectance decrease with time”) is considered to be due to factors such as crystal grain growth and Ag atom aggregation, as described in the description of the prior art. .
[0019]
Therefore, the present inventors are based on the idea that it is important to find an alloy component capable of removing or suppressing these factors in order to prevent the decrease in reflectance over time and obtain the high reflectance inherent in Ag. And conducted intensive research.
[0020]
As a result of the study, the present inventors have made Ag high reflectance by including Bi and / or Sb (one or two elements selected from the group consisting of Bi and Sb) into Ag. The present inventors have found that Ag aggregation and crystal grain growth can be suppressed while maintaining, and that a decrease in reflectance over time can be suppressed, and the present invention has been completed.
[0021]
Conventionally, studies have been made to use not only pure Ag but also an Ag-based alloy as a light reflecting film. However, as specified in the present invention, Bi or Sb is added to Ag to aggregate Ag atoms or Ag. The knowledge to suppress the growth of crystal grains is not recognized in the prior art. Regarding suppression of Ag atom aggregation and Ag crystal grain growth, there is an invention of a light reflecting film made of an Ag-based alloy to which a rare earth element is added (Japanese Patent Application No. 2002-01729). The light reflecting film made of an Ag-based alloy containing Bi and Sb has higher reflectance and durability.
[0022]
In the present invention, an Ag-based alloy containing Bi and / or Sb is used as a light reflecting film, so that a decrease in reflectance over time is suppressed and a high light reflectance is maintained. It is based on a distinguished technical idea. As will be described later, a low-cost alloy such as Nd or Y can be used for an Ag-based alloy containing Bi and / or Sb. Furthermore, a ternary or quaternary or higher alloy containing Au, Cu, Pt, Pd, and Rh, which are components that improve oxidation resistance, can also be used. Hereinafter, the present invention will be described in detail.
[0023]
In the present invention, in consideration of the fact that a light reflection film used for, for example, a reflective liquid crystal display element is required to have a visible light reflection characteristic, the reflectance was measured at a wavelength of 650 nm to examine the reflection characteristic. In the following description, “initial reflectance (%)” means the reflectance (%) immediately after forming the light reflecting film, and the magnitude of this value depends on the type and amount of the alloy element. “Reflectance change over time (%)” is defined as “reflectance after environmental test (%) − initial reflectivity (%)”, and when this change over time (%) is negative, This means that the reflectance after the environmental test is lower than the initial reflectance.
[0024]
When the light reflecting film is formed of an Ag-based alloy containing Bi and / or Sb, growth of Ag crystal grains and aggregation of Ag atoms are suppressed. In particular, a thin film formed by a sputtering method contains many defects such as atomic vacancies, so that Ag atoms are likely to move and diffuse. As a result, Ag atoms are considered to aggregate, but Bi and Sb are considered to be Ag. It is considered that the migration / diffusion of Ag atoms is suppressed by being present in the crystals of Ag, thereby suppressing the growth of Ag crystal grains and the aggregation of Ag atoms.
[0025]
By adding Bi and / or Sb in a total amount of 0.01 atomic% or more, the effect of suppressing the growth of Ag crystal grains and the aggregation of Ag atoms is exhibited. However, since the initial reflectivity decreases and the electrical resistivity increases as the addition amount of these elements increases, the total addition amount of Bi and / or Sb is preferably 4 atomic% or less. In particular, when the liquid crystal display element serves as both a reflector and an electrode, it is desirable to make the electrical resistivity as low as possible. That is, regarding the initial reflectivity, if the total addition amount of Bi and / or Sb is within 2 atomic%, a high initial reflectivity of 80% or more can be maintained. On the other hand, regarding the electrical resistivity, the electrical resistivity of Al alloys (Al-Ta, Al-Nd, etc.) usually used for the wiring film of the liquid crystal display element is about 5 to 15 μΩcm. As shown, when both Bi and Sb are within 1.8 atomic%, an electrical resistivity of 15 μΩcm or less equivalent to that of an Al alloy wiring can be obtained. However, in the case of a refractory metal material such as Cr or Mo used for the liquid crystal display element wiring film as in the case of the Al alloy, the electric resistivity is about 200 μΩcm, so that the added amounts of Bi and Sb are 1. Even when it exceeds 8 atomic%, it can be used without any problem. Therefore, the more preferable upper limit of the total amount of Bi and / or Sb is 2 atomic%.
[0026]
On the other hand, as an environmental test for facilitating reproduction of an environment in which Ag crystal grain growth and Ag atom aggregation are likely to occur, the light reflecting film is left in a high temperature and high humidity environment at a temperature of 80 ° C. and a relative humidity of 90% for 48 hours. Even if the total amount of Bi and / or Sb is 0.05 atomic% or more, the reflectance before the environmental test [= initial reflectance] (%) and the reflectance after the environmental test (%) Since the difference can be suppressed to 1% or less, the more preferable lower limit of the total amount of Bi and / or Sb is 0.05 atomic%.
[0027]
The Ag-based alloy used for forming the light reflecting film of the present invention may further contain a rare earth element, particularly Nd and / or Y. Although the effect is small compared to the above Bi and Sb, Nd and Y also have an effect of improving the aggregation resistance of Ag, and Nd and Y have a lower material cost than Bi and Sb. This is because the cost can be reduced by replacing the part. The total amount of Nd and / or Y is preferably 0.01 atomic% or more. However, since addition of Nd and Y causes a decrease in initial reflectance and electrical resistivity, the total amount is preferably 2 atomic% or less, more preferably 1 atomic% or less. (Addition of Nd and / or Y without adding Bi and / or Sb to Ag can improve the aggregation resistance of Ag. However, as described in the examples below, the NaCl resistance is improved. There is a problem not to be.)
[0028]
Further, Au, Cu, Pt, Pd, Rh, etc. may be added for the purpose of improving the oxidation resistance. These elements have no effect of suppressing Ag aggregation, but have an effect of increasing chemical stability, and have an effect of suppressing a decrease in reflectance over time. In addition, since these elements cause a decrease in reflectance particularly in a short wavelength region (around 400 nm) with an increase in addition amount, the total amount is preferably 3 atomic% or less, more preferably 2 atomic% or less. .
[0029]
The light reflecting film of the present invention contains Bi and / or Sb, optionally contains Nd, Y, or Cu, Au, Pd, Rh, Pt, and the balance is substantially Ag. Although it is a preferred embodiment for obtaining a high initial reflectance, other components than the above components may be added as long as the effects of the present invention are not impaired. For example, Zn, Ti, Mg, Ni, etc. may be added from the viewpoint of chemical corrosion and reaction prevention. Further, gas components such as Ar, O 2 and N 2 and impurities contained in the Ag-based alloy which is a melting raw material are allowed.
[0030]
Since the light reflecting film of the present invention can maintain a high reflectance for a long time, it is preferably used for a reflective liquid crystal display element. In addition, the light reflecting film of the present invention is particularly suitable for a liquid crystal display element that normally undergoes a heating process at 200 to 300 ° C. during the manufacturing process because it is excellent in resistance to structural changes such as crystal grain growth during heating. Yes. Furthermore, since this light reflection film has conductivity, it can be used as a reflection electrode of a reflective liquid crystal display element. Moreover, you may provide as a reflecting plate in the back surface of a transparent electrode. As an electrode substrate when used as a reflective electrode, a known substrate such as a glass substrate or a plastic film substrate can be used. The same substrate can be used for the reflector. Furthermore, it can also be used so that it may serve as a light reflection film and a wiring film.
[0031]
In order to form the light reflecting film on the substrate or the substrate, it is preferable to use a sputtering method. Bi and Sb have a very small solid solution limit with respect to Ag in the state of chemical equilibrium. However, in a thin film formed by a sputtering method, non-equilibrium solid solution is possible by vapor phase quenching inherent to the sputtering method. Compared to the case where an Ag-based alloy thin film is formed by the forming method, the above alloy elements are likely to exist uniformly in the Ag matrix. As a result, the oxidation resistance of the Ag-based alloy is improved, and the effect of suppressing the aggregation of Ag atoms is exhibited.
[0032]
The thickness of the light reflecting film is preferably 50 to 300 nm. In a film thinner than 50 nm, light begins to transmit, so the reflectance is low. On the other hand, if it exceeds 300 nm, there is no problem with respect to the reflectance, but it is disadvantageous in terms of productivity and cost.
[0033]
In the case of sputtering, as a sputtering target (hereinafter, also simply referred to as “target”), one selected from the group consisting of Bi: 0.2 to 15 atomic% and Sb: 0.01 to 4 atomic% or A light reflecting film having a desired chemical composition is obtained by using an Ag-based alloy containing two elements and having a Bi content and an Sb content in the sputtering target satisfying the following re-expression (1). Can do.
[0034]
0.01 ≦ 0.000502n Bi 3 + 0.00987n Bi 2 + 0.0553n Bi + n Sb ≦ 4 (1) [repost]
[0035]
Here, the reason why the Bi content in the target is set higher than the Bi content in the light reflecting film is as follows. That is, when a light reflecting film is formed by sputtering using a target made of an Ag-based alloy containing Bi, the Bi content in the light reflecting film is reduced to several percent to several tens of percent of the Bi content in the target. It is recognized that This is because Bi is re-evaporated from above the substrate during film formation because of the large difference in melting point between Ag and Bi, and Bi is difficult to be sputtered because the sputtering rate of Ag is larger than the sputtering rate of Bi. In addition, since Bi is more easily oxidized than Ag, only Bi is oxidized on the target surface and not sputtered. Thus, the phenomenon in which the element content in the light reflecting film is significantly reduced from the element content in the target is a phenomenon that is not observed in other Ag-based alloys such as an Ag—Sb alloy and an Ag—rare earth metal alloy. For this reason, the Bi content in the target needs to be higher than the Bi content in the target light reflecting film. For example, in order to obtain a light reflecting film containing 0.005 to 0.4 atomic% of Bi, in consideration of the amount of Bi not taken into the light reflecting film, the Bi content in the target is set to 0.15 to 4. It is necessary to be 5 atomic% (see Example 3 described later). As described above, the total amount of Bi and Sb contained in the light reflecting film needs to be 0.01 to 4 atomic%. For this reason, the Bi content and the Sb content in the target must satisfy the above numerical range and the following re-expression (1).
[0036]
0.01 ≦ 0.000502n Bi 3 + 0.00987n Bi 2 + 0.0553n Bi + n Sb ≦ 4 (1) [repost]
[0037]
Here, the value of each coefficient relating to n Bi in the above formula (1) is obtained by experimentally investigating the correlation between the Bi content in the target and the Bi content in the light reflecting film, and approximated from the result. It was obtained.
[0038]
As the target, it is preferable to use an Ag-based alloy (melted Ag-based alloy) produced by a melting / casting method. Since the melted Ag-based alloy is structurally uniform and the sputtering rate and the emission angle can be made constant, a light reflecting film having a uniform component composition can be obtained. If the oxygen content of the molten Ag-based alloy target is controlled to 100 ppm or less, the film formation rate can be easily kept constant, and the amount of oxygen in the light reflecting film is also reduced, so that the reflectance and electrical resistivity are improved. To do.
[0039]
The reflective liquid crystal display element of the present invention only needs to include the light reflecting film of the present invention, and the configuration of the other liquid crystal display elements is not particularly limited, and any configuration known in the field of liquid crystal display elements is adopted. be able to.
[0040]
【Example】
The present invention will be described in more detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and all modifications are included in the present invention without departing from the spirit of the present invention.
[0041]
(Example 1)
A 5 mm × 5 mm Bi or Sb metal chip was placed on a pure Ag target, and the test No. 1 in Table 1 having a thickness of 100 nm was formed on the glass substrate by DC magnetron sputtering. Samples having the component compositions shown in 1 to 12 were prepared. Regarding the composition of the thin film, a sample having a thickness of 1 μm was separately prepared under the same conditions, and the composition was identified using ICP-mass spectrometry (SPQ-8000 manufactured by Seiko Instruments Inc.). Specifically, a sample of 100 mg or more was dissolved in a nitric acid: pure water = 1: 1 solution as a pretreatment, and this was heated on a hot plate at 200 ° C. to confirm that the sample was completely dissolved, and then cooled. And analyzed. The target size is φ100 mm, and the glass substrate size is φ50 mm. The main film formation conditions are: ultimate vacuum: 6.67 × 10 −4 Pa, Ar gas pressure during film formation: 0.267 Pa, substrate temperature: 25 ° C., target-substrate distance: 55 mm.
[0042]
Immediately after film formation, the reflectance of each sample was measured with a visible ultraviolet spectrophotometer (manufactured by Shimadzu Corporation). Further, the reflectance of these samples after the environmental test (temperature 80 ° C., relative humidity 90%, time 48 h) was measured with the above spectrophotometer, and the amount of change in the reflectance before and after the environmental test was evaluated. Furthermore, the surface roughness before and after the environmental test was measured with an atomic force microscope (AFM), and the amount of change in the surface roughness before and after the environmental test was evaluated. Further, a salt water immersion test (NaCl: 0.05 mol / L, 15 min) was performed, and the degree of discoloration of the light reflecting film and the presence or absence of peeling of the light reflecting film from the substrate were visually observed to evaluate NaCl resistance.
[0043]
(Comparative Example 1)
The metal tip placed on the pure Ag target is Nd, In, Nb or Sn instead of Bi or Sb in Example 1, and the test No. in Table 1 is performed under the same film formation conditions as in Example 1. Ag alloy thin films having the compositions shown in 13 to 16 were prepared and evaluated in the same manner as in Example 1.
[0044]
The evaluation results for Example 1 and Comparative Example 1 are also shown in Table 1. As shown in Example 1 of Table 1, the amount of change in reflectance and the surface roughness before and after the environmental test were increased by addition of Bi or Sb (Test Nos. 2 to 12) compared to a pure Ag thin film (Test No. 1). It can be seen that the degree of change is significantly suppressed. As for the addition amount of Bi or Sb, the effect is recognized even at 0.01 atomic% (Test Nos. 2 and 8), but the effect is particularly large at 0.05 atomic% or more (Test Nos. 3 to 7, 9 to 12). Further, even after the salt water immersion test, it can be seen that the addition of Bi or Sb eliminates discoloration such as yellowing of the light reflecting film and peeling of the light reflecting film from the substrate, and shows good durability.
[0045]
On the other hand, as shown in Comparative Example 1 of Table 1, Ag—Nd shows a good result for the suppression of the change in reflectance before and after the environmental test, but has no NaCl resistance (Test No. 1). 13). Further, Ag—In, Ag—Nb, and Ag—Sn have a very low inhibitory effect on the amount of change in surface roughness (Test Nos. 14 to 16).
[0046]
(Example 2)
Using a composite target in which a metal tip of 5 mm × 5 mm Bi, Cu, Au, Nd, or Y is placed on a pure Ag or Ag-0.2% Sb target, the film formation conditions are the same as in Example 1. A sample was prepared. Table 2 shows the results of evaluation similar to Example 1 for these samples. Table 2 shows the test No. in Table 1 for comparison. 1 and 4 are reprinted.
[0047]
It can be seen that addition of Nd or Y to Ag-Bi further improves the surface roughness and the amount of change thereof (Test Nos. 17 and 18). Further, when Cu or Au is further added to Ag—Bi or Ag—Sb, it is found that there is an effect of reducing the change in reflectance although there is no further effect of improving the surface roughness (Test No. 1). 19-24).
[0048]
[Table 1]
[Table 2]
(Example 3)
Bi was added to pure Ag with various addition amounts and melted to prepare an Ag-Bi alloy target. Using this target, a thin film was produced under the same film forming conditions as in Example 1. And Bi content in a target and a thin film was measured by the same ICP-mass spectrometry as Example 1. Table 3 shows the measurement results. As shown in Table 3, the Bi content in the thin film is several percent to several tens of percent of the Bi content in the target, and in order to make the Bi content in the thin film 0.01 to 4 atom%, the target It turns out that it is necessary to make Bi content in 0.2 to 15 atomic%.
[0051]
[Table 3]
【The invention's effect】
As described above, according to the present invention, a high-performance light reflecting film having a high light reflectance substantially equal to the original high light reflectance of Ag, a liquid crystal display element using the light reflecting film, and this A sputtering target for forming a light reflecting film can be provided.
Claims (6)
式 ０．０１≦０．０００５０２ｎＢｉ ３＋０．００９８７ｎＢｉ ２＋０．０５５３ｎＢｉ＋ｎＳｂ≦４
ここに、ｎＢｉはスパッタリングターゲット中のＢｉ含有量（原子％）、ｎＳｂはスパッタリングターゲット中のＳｂ含有量（原子％）を意味する。It is a sputtering target used in order to form the light reflection film of any one of Claims 1-4 on a board | substrate, Comprising: Bi: 0.2-15 atom% and Sb: 0.01-4 atom The light reflection is characterized by comprising an Ag-based alloy containing one or two elements selected from the group consisting of 1% and a Bi content and Sb content in the sputtering target satisfying the following formula: Sputtering target for film.
Formula 0.01 ≦ 0.000502n Bi 3 + 0.00987n Bi 2 + 0.0553n Bi + n Sb ≦ 4
Here, n Bi means Bi content (atomic%) in the sputtering target, and n Sb means Sb content (atomic%) in the sputtering target.
Priority Applications (21)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003003643A JP4105956B2 (en) | 2002-08-08 | 2003-01-09 | Light reflection film, liquid crystal display device using the same, and sputtering target for light reflection film |
| US10/633,550 US7514037B2 (en) | 2002-08-08 | 2003-08-05 | AG base alloy thin film and sputtering target for forming AG base alloy thin film |
| SG200304812A SG103935A1 (en) | 2002-08-08 | 2003-08-06 | Ag base alloy thin film and sputtering target for forming ag base alloy thin film |
| DE10362283.7A DE10362283B4 (en) | 2002-08-08 | 2003-08-07 | Production method for Ag alloy based film and sputtering target |
| TW94121903A TWI265976B (en) | 2002-08-08 | 2003-08-07 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| DE10336228A DE10336228B4 (en) | 2002-08-08 | 2003-08-07 | Ag alloy based thin film, use of this film and manufacturing process for this film |
| DE10362302.7A DE10362302B4 (en) | 2002-08-08 | 2003-08-07 | Electromagnetic shielding film product and manufacturing method therefor |
| TW92121689A TWI263689B (en) | 2002-08-08 | 2003-08-07 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| CNB031274617A CN1256461C (en) | 2002-08-08 | 2003-08-07 | Ag base alloy thin film and sputtering target for forming Ag base alloy film |
| KR1020030055105A KR100605840B1 (en) | 2002-08-08 | 2003-08-08 | Ag-BASED THIN FILM AND A SPUTTERING TARGET FOR FORMING THE SAME |
| US11/313,815 US7419711B2 (en) | 2002-08-08 | 2005-12-22 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| US11/353,168 US7566417B2 (en) | 2002-08-08 | 2006-02-14 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| KR1020060017733A KR20060021939A (en) | 2002-08-08 | 2006-02-23 | Ag-based alloy thin film and sputtering target for forming Ag-based alloy thin film |
| US11/395,227 US20060171842A1 (en) | 2002-08-08 | 2006-04-03 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| US11/401,853 US7722942B2 (en) | 2002-08-08 | 2006-04-12 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| US12/100,823 US7758942B2 (en) | 2002-08-08 | 2008-04-10 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| KR1020080066739A KR100895759B1 (en) | 2002-08-08 | 2008-07-09 | LIQUID CRYSTAL DISPLAY DEVICE COMPRISING Ag-BASED OPTICAL REFLECTIVE FILM |
| US12/183,700 US7871686B2 (en) | 2002-08-08 | 2008-07-31 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| US12/342,507 US7776420B2 (en) | 2002-08-08 | 2008-12-23 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| US12/915,138 US8178174B2 (en) | 2002-08-08 | 2010-10-29 | Ag base alloy thin film and sputtering target for forming Ag base alloy thin film |
| US13/437,350 US8936856B2 (en) | 2002-08-08 | 2012-04-02 | AG base alloy thin film and sputtering target for forming AG base alloy thin film |
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| JP2003003643A JP4105956B2 (en) | 2002-08-08 | 2003-01-09 | Light reflection film, liquid crystal display device using the same, and sputtering target for light reflection film |
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| US9947429B2 (en) | 2013-06-26 | 2018-04-17 | Kobe Steel, Ltd. | Ag alloy film for reflecting electrode or wiring electrode, reflecting electrode or wiring electrode, and Ag alloy sputtering target |
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