JP2004050643A - Thin film laminated body - Google Patents
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Abstract
Description
【０００１】
【発明の属する技術分野】
本発明は、液晶ディスプレイ素子やプラズマディスプレイ素子、有機ＥＬディスプレイ素子などに用いられる低抵抗の透明電極用の薄膜積層体に関する。
【０００２】
【従来の技術】
酸化物透明導電性薄膜は、高い導電性と可視光領域での高い透過率とを有している。
【０００３】
このため、酸化物透明導電性薄膜は太陽電池、液晶表示素子、その他各種受光素子等の電極として、あるいは近赤外域の波長における反射吸収特性を生かして自動車窓ガラスや建築物の窓ガラス等に用いる熱線反射膜として、あるいは各種の帯電防止膜、冷凍ショーケースなどの防曇用の透明発熱体として利用されている。
【０００４】
酸化物透明導電性薄膜には、アンチモンやフッ素がドーピングされた酸化錫（ＳｎＯ２）膜や、アルミニウムやガリウムがドーピングされた酸化亜鉛（ＺｎＯ）膜や、錫がドーピングされた酸化インジウム（Ｉｎ２Ｏ３）膜などが広範に利用されている。特に錫がドーピングされた酸化インジウム膜、すなわちＩｎ２Ｏ３−Ｓｎ系膜はＩＴＯ（Ｉｎｄｉｕｍ ｔｉｎ ｏｘｉｄｅ）膜と称され、低抵抗の膜が容易に得られることから良く用いられている。
【０００５】
これらの酸化物透明導電性薄膜の製造方法としてはスパッタリング法や蒸着法、透明導電層形成用塗液を塗布する方法が良く用いられている。特に、スパッタリング法は、蒸気圧の低い材料を用いて被成膜物質（以下、単に「基板」と示す。）上に膜を形成する場合や、精密な膜厚制御が必要とされる際に有効な手法であり、操作が非常に簡便であることから広範に利用されている。
【０００６】
スパッタリング法は一般に、約１０Ｐａ以下のアルゴンガス圧のもとで、基板を陽極とし、ターゲットを陰極としてこれらの間にグロー放電を起こしてアルゴンプラズマを発生させ、プラズマ中のアルゴン陽イオンを陰極のターゲットに衝突させ、これによってターゲット成分の粒子をはじき飛ばし、該粒子を基板上に堆積させて成膜するというものである。
【０００７】
スパッタリング法は、アルゴンプラズマの発生方法で分類され、高周波プラズマを用いるものは高周波スパッタリング法、直流プラズマを用いるものは直流スパッタリング法という。また、ターゲットの裏側にマグネットを配置してアルゴンプラズマをターゲット直上に集中させ、低ガス圧でもアルゴンイオンの衝突効率を上げて成膜する方法をマグネトロンスパッタリング法という。通常、上記の酸化物透明導電性薄膜の製造法には直流マグネトロンスパッタリング法が採用されている。
【０００８】
一般に、ＩＴＯ膜や酸化インジウム膜の室温成膜による膜では、結晶相と非晶質相との混在した膜が得られやすく、そのような膜で積層体の最表面を覆うと表面の凹凸は激しくなってしまう。また結晶相が存在すれば結晶粒界が存在し、この粒界から金属膜の拡散染みだしや腐食が起こりやすく、特性を変化させてしまうおそれがある。
【０００９】
建築窓用の熱線遮蔽膜などの用途には特に表面を被覆する酸化物膜の結晶性が問題になってくる。すなわち、結晶性の良いほうが耐環境性が劣ることになる。
【００１０】
一方、ＬＣＤや有機ＥＬ用の電極としては、表面が平滑で低抵抗な透明導電膜が必要とされている。特に有機ＥＬ用の電極の場合、該透明導電膜の上に有機化合物の超薄膜を形成するため、優れた表面平滑性が要求される。
【００１１】
膜表面の平滑性は、一般に膜の結晶性に大きく左右される。同一組成であっても結晶粒界の存在しない非晶質膜の方が結晶粒界のある結晶性の膜に比較して表面平滑性は良好である。従来組成のＩＴＯ膜の場合には、成膜時の基板温度を下げて（１５０℃以下の低温で）スパッタリング成膜して得た非晶質ＩＴＯ膜の方が表面平滑性に優れていることが知られている。
【００１２】
しかし、非晶質ＩＴＯ膜の比抵抗は６〜８×１０−４Ω・ｃｍ程度が限界で、それより低抵抗化することは難しく、シート抵抗の低い電極膜を形成するためには膜厚を厚くする必要があった。例えば、７０〜１５０ｎｍの膜厚では、４０Ω／□程度が限界であった。また、ＩＴＯ膜の膜厚が厚くなると膜の着色の問題が生じてしまうだけでなく、材料コストをあげてしまうという新たな問題も出てくる。
【００１３】
また、非晶質膜を得ようとして基板を加熱せずに成膜したＩＴＯ膜では、スパッタリングガス圧が低いと、基板に入射するスパッタ粒子の運動エネルギーが高いため、局所的に温度が上がり、微細な結晶相と非晶質相で構成された膜が得られてしまうことがわかっている。これは、Ｘ線回折のほか、透過型電子顕微鏡の解析でも確認されている。このように微細な結晶相が一部で形成されていると、膜の表面平滑性に多少の影響を及ぼす。また膜を所定の形状に弱酸でエッチング除去する際には、結晶相のみが除去できずに残存することがあり、問題となっている。
【００１４】
上記の問題を解決するために、発明者は、完全に非晶質構造をとり、表面が平滑な酸化インジウム系透明導電膜の開発を行ってきた。例えば、特開平６−２３４５６５号公報にはＺｎが含有されたＩｎ２Ｏ３材料、特開平１１−３２３５３１号公報にはＧｅが含有されたＩｎ２Ｏ３材料が記載されている。
【００１５】
発明者はさらに、特願２００２−１５７５６８号にはＳｉが含有されたＩｎ２Ｏ３材料、特願２００２−１５７５６８号にはＷが含有されたＩｎ２Ｏ３材料を開発している。これらの材料では、基板温度を低温にしたスパッタリング成膜で安定に非晶質膜が得られており、拡散染みだしや腐食を防止でき、表面平滑性に優れた膜となっている。
【００１６】
他の課題として、ＳＴＮ（ｓｕｐｅｒ ｔｗｉｓｔｅｄ ｎｅｍａｔｉｃ）方式を用いた単純マトリックス液晶素子では透明電極が走査信号用電極と画素電極を兼ねているため、高精細化に伴う極めて低いシート抵抗を有する透明電極の開発が急がれている。また、画素密度を増大させて緻密な画面を表示するためには、透明電極パターンの緻密化が要求されており、その場合、１００μｍ程度のピッチで透明電極の端子部を構成することが要求されている。そのような透明電極を実現するためには、透明電極の薄膜化（例えば１００〜１５０ｎｍ）と優れたエッチング加工適性、低いシート抵抗が必要となる。
【００１７】
また、表示画面の大型化も求められており、大型化にともなって、上述のような緻密パターンの透明電極を形成ししかも液晶に十分な駆動電圧を印加できるようにするためには、シート抵抗値５Ω／□以下、好ましくは３Ω／□以下という透明電極として低いシート抵抗値が必要であり、すなわち高い導電性を備えている必要があった。
【００１８】
しかし、上記の非晶質酸化インジウム系材料では、非晶質であるためエッチング特性は良好であるものの、比抵抗は３〜６×１０−４Ωｃｍ程度であるため、膜厚が１００〜１５０ｎｍの電極膜ではおよそ４０Ω／□のシート抵抗が限界であった。したがって、非晶質酸化インジウム系材料では上記のようなディスプレイの高精細化や大型化には対応できなかった。
【００１９】
ところで、金属膜と酸化インジウム系薄膜との薄膜積層体の技術は従来からある。例えば、１９８２年、日本で開催された第７回ＩＣＶＭにおいては、熱線反射膜として銀薄膜の表裏面にＩＴＯ膜もしくは酸化インジウム膜を積層させて構成される３層構造の透明導電膜が提案されている。銀薄膜の介在は抵抗値低減のためで、この透明導電膜はシート抵抗は５Ω／□であり、その高い導電性を活かして上記の表示デバイスへの透明電極への応用が期待された。しかしこの技術では、透明導電膜の表面の粗さについては言及されていなかった。
【００２０】
また、銀系導電薄膜層の両側に酸化セリウムや酸化チタンを加えた透明導電薄膜層を設けた積層体を基板に設けた電極基板は、特開平９−３０５１２６号公報に記載されている。しかし、酸化セリウムや酸化チタンは高屈折率材料として加えられているので、それら以外の酸化物系透明導電薄膜層を示唆するものは無い。
【００２１】
【発明が解決しようとする課題】
以上述べたように、粒界の存在に伴う拡散染みだしや腐食が防止でき、膜厚７０〜１５０ｎｍでも１〜５Ω／□のシート抵抗を有するだけでなく、表面が平滑である透明電極膜は、ＬＣＤだけでなく、将来のディスプレイとして注目されているプラズマディスプレイ、有機ＥＬディスプレイでも同じ理由で有用とされているが、これまでの技術ではこのような透明電極膜は実現できなかった。
【００２２】
本発明は、粒界の存在に伴う拡散染みだしや腐食が防止でき、膜厚７０〜１５０ｎｍでも１〜５Ω／□のシート抵抗を有し、表面平滑性に優れ、透明性に優れ、高精細もしくは大型のＬＣＤや、プラズマディスプレイ、有機ＥＬ用透明電極として有用な薄膜積層体を提供することを目的とする。
【００２３】
【課題を解決するための手段】
本発明の薄膜積層体は、上記目的を達成するために以下の特徴を持つ。
【００２４】
すなわち、本発明の薄膜積層体は、金属系導電薄膜層と酸化物系透明導電薄膜層の２層、または酸化物系透明導電薄膜層が金属系導電薄膜層の両側に設けられた３層からなり、酸化物系透明導電薄膜層として、タングステン、シリコン、ゲルマニウムから選ばれた１種以上が含有される非晶質の酸化インジウムが積層されていることを特徴とする薄膜積層体である。
【００２５】
金属系導電薄膜層は、銀、銀−金系合金、銀−パラジウム系合金、金、白金、パラジウムのうち少なくとも１種類で構成されることが好ましい。金属系導電薄膜層の厚みは２０ｎｍ以下が好ましい。
【００２６】
酸化物系透明導電薄膜層あるいは金属系導電薄膜層が薄膜積層体の表面を形成するが、この表面の中心線平均表面粗さＲａを１．５以下にすることが好ましい。
【００２７】
酸化物系透明導電薄膜層の厚さは、４ｎｍ以上が好ましい。
【００２８】
酸化物系透明導電薄膜層が、タングステンが含有される酸化インジウム薄膜である場合、タングステン／インジウム原子数比が０．００４〜０．１７の割合であることが好ましい。
【００２９】
酸化物系透明導電薄膜層が、シリコンが含有される酸化インジウム薄膜である場合、シリコン／インジウム原子数比が０．００２〜０．１５の割合であることが好ましい。
【００３０】
酸化物系透明導電薄膜層が、ゲルマニウムが含有される酸化インジウム薄膜である場合、ゲルマニウム／インジウム原子数比が０．００２〜０．１５の割合であることが好ましい。
【００３１】
薄膜積層体の全体の膜厚が７０〜１５０ｎｍであるとき、シート抵抗が５Ω／□以下であることが好ましい。
【００３２】
本発明の別の態様では、前記薄膜積層体が基板の上に設けられ、薄膜積層体付き透明基材が形成される。この場合、基板に接するのは、酸化物系透明導電薄膜層と金属系導電薄膜層のいずれでも良い。そして、基板に対し反対側が表面となる。また、基板は、例えばディスプレイ素子のガラス板で、この上に前記薄膜積層体が成膜される。
【００３３】
【発明の実施の形態】
薄膜積層体
本発明の実施態様に係わる薄膜積層体は、タングステン、ゲルマニウム、シリコンのうち少なくとも１元素が含まれた非晶質の酸化インジウム薄膜で代表される酸化物系透明導電薄膜層が、銀、銀−金系合金、銀−パラジウム系合金、金、白金、パラジウムのうちの少なくとも１種類の金属系導電薄膜層の片側もしくは両側に積層されたものであり、金属系導電薄膜層の表面の片側あるいは両側を酸化物系透明導電薄膜層が覆うような構造をとる。この薄膜積層体は、基板上に成膜で形成され薄膜積層部材を構成するが、基板に直接接するのは、金属系導電薄膜層でも、酸化物系透明導電薄膜層でもよい。基板と反対側が表面となる。
【００３４】
薄膜積層体の全体の膜厚が７０〜１５０ｎｍにおいて、シート抵抗が５Ω／□以下の透明電極が実現できる。このような特性が実現できることから、高精細ＬＣＤやプラズマディスプレイ、有機ＥＬ等の表示デバイス用の透明電極、建築窓用の熱線遮蔽膜等として有用である。
【００３５】
酸化物系透明導電薄膜層
酸化インジウムにタングステン、ゲルマニウム、シリコンのうち少なくとも１元素を含させる理由は、次の通りである。すなわち、発明者の実験によると、酸化物系透明導電薄膜層である酸化インジウム薄膜中の添加元素は、タングステンが含まれる場合はタングステン／インジウム原子数比で０．００４〜０．００９６の割合であり、ゲルマニウムが含まれる場合はゲルマニウム／インジウム原子数比で０．００２〜０．１７の割合で含まれ、シリコンが含まれる場合はシリコン／インジウム原子数比で０．００２〜０．１５の割合で含まれる場合、このような組成の酸化インジウム系薄膜は非晶質構造をとりやすい。前記範囲より少ないと非晶質の完全性がくずれ、多くなると他の結晶相が析出したり、結晶化しやすくなってしまう。特に、基板を加熱せずにスパッタ成膜を行った場合は、結晶質相を含まない完全に非晶質構造の薄膜が得られるため、膜表面の凹凸は極めて小さくなる。このような性質の酸化インジウム系薄膜を薄膜積層体の表面に用いることによって、膜の表面粗さが小さい薄膜積層体が得られる。
【００３６】
酸化インジウム薄膜を非晶質とする理由は次の通りである。すなわち、一般に、薄膜中の物質の移動は結晶粒界に沿って高頻度に発生する。非晶質構造をとる酸化インジウム系薄膜には、結晶粒界が存在しない。従って、結晶粒界を介して大気から汚染が拡散する腐食を防ぐことができる。
【００３７】
上記構成の酸化インジウム薄膜であると、結晶質相を含まない完全に非晶質構造の薄膜が得られるため、膜表面の凹凸は極めて小さくなり、中心線平均表面粗さＲａが１．５以下となる。
【００３８】
金属系導電薄膜層
金属系導電薄膜層に銀、銀−金系合金、銀−パラジウム系合金、金、白金、パラジウムのうちの少なくとも１種類を用いた理由は、上記金属系導電薄膜層は、可視光領域の透過率は低いが、中心線平均表面粗さＲａが１．５以下で表面の凹凸は極めて小さく、厚みを２０ｎｍ以下に設定することによって６０％以上の透過率を維持することが可能であり、金属系導電薄膜層の極めて高い電気伝導性を利用することができるからである。そして、前記酸化インジウム系薄膜で金属系導電薄膜層を覆えば、金属と大気の接触による腐食を防ぐことができる。
【００３９】
薄膜積層体付き透明基材
前記薄膜積層体を、ガラス基板などに成膜すれば、例えば透明電極として液晶ディスプレイ素子などの薄膜積層体付き透明基材を構成できる。
【００４０】
【実施例】
成膜には６インチφの非磁性体ターゲット用カソードが２ヶ搭載された直流マグネトロンスパッタリング装置を使用した。カソード１には６インチφ×５ｍｍｔの酸化インジウム系酸化物焼結体スパッタリング用ターゲットを取り付け、カソード２には６インチφ×５ｍｍｔの金属系ターゲットを取り付けた。基板には石英ガラス基板を用い、ガラス基板は各カソードの対向面に移動して静止させることが可能で、各膜は静止対向にて成膜を行った。
【００４１】
酸化物系透明導電薄膜層の成膜は以下の条件で行った。酸化インジウム系酸化物焼結体ターゲットと基板との距離を６０ｍｍとし、チャンバ内の真空度が１×１０−４Ｐａ以下に達した時点で、純度９９．９９９９質量％のＡｒガスをチャンバ内に導入してガス圧０．６Ｐａとし、酸素を１％成膜ガス中に導入させて、直流電力２００Ｗをターゲット−基板間に投入して直流プラズマを発生させ、基板を加熱せずにスパッタリング成膜を実施した。膜厚は成膜時間で制御した。
【００４２】
金属系導電薄膜層の成膜は以下の条件で行った。ターゲットと基板との距離を６０ｍｍとし、チャンバ内の真空度が１×１０−４Ｐａ以下に達した時点で、純度９９．９９９９質量％のＡｒガスをチャンバ内に導入してガス圧０．６Ｐａとし、直流電力１００Ｗをターゲット−基板間に投入して直流プラズマを発生させ、基板を加熱せずにスパッタリング成膜を実施した。膜厚は成膜時間で制御した。
【００４３】
上記の条件で金属系導電薄膜層と酸化物系透明導電薄膜層とを積層させ、以下の２種類の構造の薄膜積層体を作製した。
【００４４】
１）基板／金属系導電薄膜層／酸化物系透明導電薄膜層
２）基板／酸化物系透明導電薄膜層／金属系導電薄膜層／酸化物系透明導電薄膜層
薄膜積層体のシート抵抗を四端針法で測定し、透過率の光波長依存性を分光光度計（日立製作所製）で測定した。また、薄膜積層体表面の１ｍｍ×１ｍｍの領域で中心線平均粗さＲａを原子間力顕微鏡（デジタルインスツルメント社製、ＮａｎｏＳｃｏｐｅＩＩＩ）で５カ所測定し、その平均値を求めた。また各膜の組成はＩＣＰ発光分析法とＥＰＭＡで決定した。
【００４５】
（実施例１〜１３）
カソード１にタングステンを添加した酸化インジウムの焼結体ターゲットを設置し、カソード２にＡｇ−Ｐｄ系合金ターゲット（Ｐｄ含有量１質量％）を設置して、１）と２）のタイプの薄膜積層体を形成した例を表１と表２に示す。
【００４６】
【表１】
【表２】
表１と２に示すように、本発明の薄膜積層体は総膜厚が７０〜１３５ｎｍと薄いのにも関わらずシート抵抗は２．０〜４．５Ω／□と非常に低抵抗であり、薄膜積層体表面の中心線平均粗さＲａは１．２〜１．５ｎｍと非常に小さく表面が平坦である。また可視光透過率は全て７０％以上であり、表示デバイスとして用いる際には満足できる透過率である。
【００４９】
また、実施例１〜１３では金属系導電薄膜層にＡｇ−Ｐｄ系合金薄膜を用いた例を示したが、Ａｇ薄膜、Ａｇ−Ａｕ系薄膜、Ａｇ−Ａｕ−Ｃｕ系薄膜、Ａｕ薄膜、Ｐｔ薄膜、Ｐｄ薄膜を用いた場合も同様の効果がみられた。
【００５０】
（実施例１４〜２５）
カソード１にシリコンを添加した酸化インジウムの焼結体ターゲットを設置し、カソード２にＡｇ−Ａｕ−Ｃｕ系合金ターゲット（Ａｕ含有量１質量％、Ｃｕ含有量０．５質量％）を設置して、１）と２）のタイプの薄膜積層体を形成した例を表３と表４に示す。
【００５１】
【表３】
【表４】
表３と４に示すように、本発明の薄膜積層体は総膜厚が１０５〜１３５ｎｍと薄いのにも関わらずシート抵抗は２．０〜４．５Ω／□と非常に低抵抗であり、薄膜積層体表面の中心線平均粗さＲａは１．１〜１．５ｎｍと非常に小さく表面が平坦である。また可視光透過率は全て７０％以上であり、表示デバイスとして用いる際には満足できる透過率である。
【００５４】
また、実施例１４〜２５では金属系導電薄膜層にＡｇ−Ａｕ−Ｃｕ系合金薄膜を用いた例を示したが、Ａｇ薄膜、Ａｇ−Ｐｄ系薄膜、Ａｇ−Ａｕ系薄膜、Ａｕ薄膜、Ｐｔ薄膜、Ｐｄ薄膜を用いた場合も同様の効果がみられた。
【００５５】
（実施例２６〜３６）
カソード１にゲルマニウムを添加した酸化インジウムの焼結体ターゲットを設置し、カソード２にＡｇ−Ｐｄ系合金ターゲット（Ｐｄ含有量３質量％）を設置して、１）と２）のタイプの薄膜積層体を形成した例を表５と表６に示す。
【００５６】
【表５】
【表６】
表５と６に示すように、本発明の薄膜積層体は総膜厚が１０５〜１２０ｎｍと薄いのにも関わらずシート抵抗は２．２〜４．２Ω／□と非常に低抵抗であり、薄膜積層体表面の中心線平均粗さＲａは１．０〜１．５ｎｍと非常に小さく表面が平坦である。また可視光透過率は全て７０％以上であり、表示デバイスとして用いる際には満足できる透過率である。
【００５９】
ゲルマニウムを含む酸化インジウム薄膜も、室温での成膜で完全に非晶質の膜となりやすく、表面粗さが小さい。よって、銀などの金属膜と積層させることによってシート抵抗が５Ω／□以下でＲａが１．５ｎｍ以下の薄膜積層体を作ることができる。
【００６０】
また、実施例２６〜３６では金属系導電薄膜層にＡｇ−Ｐｄ系薄膜を用いた例を示したが、Ａｇ−Ａｕ系薄膜、Ａｇ薄膜、Ａｇ−Ａｕ−Ｃｕ系薄膜、Ａｕ薄膜、Ｐｔ薄膜、Ｐｄ薄膜を用いた場合も同様の効果がみられた。
【００６１】
また、実施例１〜３６と同様に、酸化インジウム系酸化物薄膜として、タングステンとスズを含む酸化インジウム薄膜を用いても、シリコンとスズを含む酸化インジウム薄膜を用いても、タングステンとシリコンを含む酸化インジウム薄膜を用いても同様の結果であった。つまり、酸化インジウム薄膜にタングステンかシリコンの少なくとも一方の元素が含まれていれば、室温にて成膜した膜は非晶質構造をとりやすいため表面粗さが小さく、また低抵抗であるため、薄膜積層体のシート抵抗は低かった。
【００６２】
また、実施例１〜３６では金属系導電薄膜層にＡｇ−Ｐｄ系薄膜を用いた例を示したが、Ａｇ−Ａｕ系薄膜、Ａｇ−Ａｕ−Ｃｕ系薄膜、Ａｇ系薄膜、Ａｕ薄膜、Ｐｔ薄膜、Ｐｄ薄膜を用いた場合も同様の効果がみられることを確認した。Ａｇ−Ａｕ系薄膜、Ａｇ−Ａｕ−Ｃｕ系薄膜、Ａｇ系薄膜、Ａｕ薄膜、Ｐｔ薄膜、Ｐｄ薄膜はＡｇ−Ｐｄ薄膜と同様に、数十〜数百ｎΩｍの低抵抗を示すため、上記酸化インジウム薄膜との積層構造をとることによって同様の効果の薄膜積層体を得ることができる。
【００６３】
また、上記の実施例では基板をガラス基板から樹脂基板や酸化シリコン膜を施した樹脂基板にかえて同様の膜作製を試みたが、結果は同じであった。
【００６４】
（比較例１〜１６）
カソード１にスズを添加した酸化インジウムの焼結体ターゲットを設置し、カソード２にＡｇ−Ｐｄ系合金ターゲット（Ｐｄ含有量１質量％）を設置して、１）と２）のタイプの薄膜積層体を形成した例を表７示す。
【００６５】
【表７】
【表８】
表７と表８に示すように、従来のＳｎ添加Ｉｎ２Ｏ３膜とＡｇ−Ｐｄ系膜との積層による薄膜積層体では、シート抵抗は４．３Ω／□以下と低い。しかし、原子間力顕微鏡の観察によると、比較例１〜１６の薄膜積層体はＳｎ添加Ｉｎ２Ｏ３膜が非晶質相と結晶相の混合状態となっており、結晶相が存在した。
【００６８】
上記薄膜積層体を、８５℃、湿度８５％の雰囲気内に１００時間保持してその表面を観察した結果、実施例１〜３６の薄膜積層体は外観変化もなく高温耐湿性が高かったが、比較例１〜１６は変色して抵抗値も増加し高温耐湿性の低いものであることがわかった。一般に、薄膜中の物質の移動は結晶粒界に沿って高頻度に発生する。実施例１〜３６の酸化インジウム系薄膜は、非晶質構造をとるため結晶粒界が存在せず、このような酸化インジウム系薄膜で金属系導電薄膜層を覆えば、金属の粒界での拡散や、金属と大気の接触による粒界での腐食を防ぐことができる。それに対し、比較例１〜１６の酸化インジウム系薄膜は結晶相を含むため粒界が存在し、酸化インジウム系薄膜の粒界付近の金属系導電薄膜層から腐食が起きてしまう。したがって、腐食性を考慮しなければならない用途には使用できない。
【００６９】
また、表面粗さＲａも２．４〜３．５ｎｍであり表面の凹凸が大きくなっている。よって、このような薄膜積層体は、ＬＣＤや有機ＥＬの透明電極には使用することができない。結晶相の突起が薄膜積層体の表面に表れて表面凹凸を大きくしている。
【００７０】
（比較例１７〜１９）
金属相を挿入しない酸化インジウム相のみの薄膜を作製した。Ｓｎ添加Ｉｎ２Ｏ３膜を石英ガラス上に１１５〜１３０ｎｍだけ積層し、シート抵抗と表面粗さを測定した結果を表９に示す。
【００７１】
【表９】
シート抵抗は３２〜４０Ω／□と高く、また中心線平均粗さは３．２〜４．５ｎｍと大きく表面の凹凸が激しい。よって、高精細ＬＣＤや有機ＥＬ用の透明電極には用いることはできない。
【００７３】
【発明の効果】
以上詳述したように、本発明の薄膜積層体は、結晶粒界の存在に伴う拡散染みだしや腐食が防止でき、耐候性などが要求される用途にも使用することができ、膜厚７０〜１５０ｎｍでも１〜５Ω／□のシート抵抗を有し、表面平滑性にも優れ、また透明性に優れ、高精細もしくは大型のＬＣＤや、プラズマディスプレイ、有機ＥＬ用透明電極として有用である。このような薄膜積層体による透明電極は、高精細化や大型化の要求に満足する、薄くて低いシート抵抗を有するＬＣＤ用の透明電極として有用である。また同様の理由で、将来のディスプレイとして注目されている有機ＥＬ用の透明電極にも有用であり、工業的に極めて価値の高いものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin-film laminate for a low-resistance transparent electrode used for a liquid crystal display element, a plasma display element, an organic EL display element, and the like.
[0002]
[Prior art]
The oxide transparent conductive thin film has high conductivity and high transmittance in a visible light region.
[0003]
For this reason, the oxide transparent conductive thin film is used as an electrode for solar cells, liquid crystal display devices, and other various light receiving devices, or as a window glass for automobiles and buildings utilizing the reflection and absorption characteristics at wavelengths in the near infrared region. It is used as a heat ray reflective film to be used, as various antistatic films, and as a transparent heating element for anti-fog such as a frozen showcase.
[0004]
Examples of the oxide transparent conductive thin film include a tin oxide (SnO 2 ) film doped with antimony and fluorine, a zinc oxide (ZnO) film doped with aluminum and gallium, and indium oxide (In 2 oxide) doped with tin. O 3 ) films and the like are widely used. In particular, an indium oxide film doped with tin, that is, an In 2 O 3 —Sn-based film is called an ITO (Indium tin oxide) film, and is often used because a low-resistance film can be easily obtained.
[0005]
As a method for producing these oxide transparent conductive thin films, a sputtering method, an evaporation method, and a method of applying a coating liquid for forming a transparent conductive layer are often used. In particular, the sputtering method is used when a film is formed on a film-forming substance (hereinafter simply referred to as a “substrate”) using a material having a low vapor pressure or when precise film thickness control is required. It is an effective method and is widely used because its operation is very simple.
[0006]
In general, the sputtering method uses a substrate as an anode and a target as a cathode under an argon gas pressure of about 10 Pa or less to generate a glow discharge between them to generate argon plasma, and to discharge argon cations in the plasma to the cathode. The target is made to collide with the target, thereby repelling particles of the target component, and depositing the particles on a substrate to form a film.
[0007]
The sputtering method is classified by a method of generating argon plasma, and a method using high-frequency plasma is called a high-frequency sputtering method, and a method using DC plasma is called a DC sputtering method. In addition, a method in which a magnet is arranged on the back side of the target so that the argon plasma is concentrated just above the target, and a film is formed by increasing the collision efficiency of argon ions even at a low gas pressure, is called a magnetron sputtering method. Normally, a direct current magnetron sputtering method is employed as a method for producing the above-mentioned oxide transparent conductive thin film.
[0008]
In general, a film obtained by forming an ITO film or an indium oxide film at room temperature can easily obtain a mixed film of a crystalline phase and an amorphous phase. It gets intense. In addition, if a crystal phase is present, crystal grain boundaries are present, and diffusion and seepage or corrosion of the metal film are likely to occur from these grain boundaries, which may change characteristics.
[0009]
For applications such as a heat ray shielding film for architectural windows, the crystallinity of the oxide film covering the surface is particularly problematic. That is, the better the crystallinity, the lower the environmental resistance.
[0010]
On the other hand, as an electrode for LCD or organic EL, a transparent conductive film having a smooth surface and low resistance is required. In particular, in the case of an electrode for an organic EL, excellent surface smoothness is required because an ultrathin organic compound film is formed on the transparent conductive film.
[0011]
In general, the smoothness of the film surface largely depends on the crystallinity of the film. Even with the same composition, an amorphous film having no crystal grain boundary has better surface smoothness than a crystalline film having a crystal grain boundary. In the case of an ITO film having a conventional composition, the amorphous ITO film obtained by lowering the substrate temperature at the time of film formation (at a low temperature of 150 ° C. or less) has better surface smoothness. It has been known.
[0012]
However, the specific resistance of the amorphous ITO film is limited to about 6 to 8 × 10 −4 Ω · cm, and it is difficult to lower the specific resistance. To form an electrode film having a low sheet resistance, the film thickness is low. Needed to be thicker. For example, at a film thickness of 70 to 150 nm, the limit is about 40 Ω / □. In addition, when the thickness of the ITO film is increased, not only the problem of coloring of the film occurs but also a new problem that the material cost increases.
[0013]
In addition, in the case of an ITO film formed without heating the substrate in order to obtain an amorphous film, if the sputtering gas pressure is low, the kinetic energy of sputtered particles incident on the substrate is high, so that the temperature locally increases, It is known that a film composed of a fine crystal phase and an amorphous phase is obtained. This has been confirmed by transmission electron microscope analysis in addition to X-ray diffraction. When such a fine crystal phase is partially formed, the surface smoothness of the film is somewhat affected. Further, when the film is removed by etching with a weak acid into a predetermined shape, only the crystal phase may not be removed and may remain, which is a problem.
[0014]
In order to solve the above problem, the inventor has developed an indium oxide-based transparent conductive film having a completely amorphous structure and a smooth surface. For example, In 2 O 3 material Zn is contained in JP-A-6-234565, In 2 O 3 material Ge is contained in JP-A-11-323531 is described.
[0015]
Inventors further developed In 2 O 3 material Si is contained in the Japanese Patent Application No. 2002-157568, the In 2 O 3 material W is contained in the Japanese Patent Application No. 2002-157568. With these materials, an amorphous film is stably obtained by sputtering film formation at a low substrate temperature, and diffusion exudation and corrosion can be prevented, and the film has excellent surface smoothness.
[0016]
Another problem is that, in a simple matrix liquid crystal element using a super twisted nematic (STN) method, the transparent electrode also serves as a scanning signal electrode and a pixel electrode. Development is urgent. Further, in order to increase the pixel density and display a dense screen, it is required to make the transparent electrode pattern dense. In this case, it is necessary to form the terminal portions of the transparent electrode at a pitch of about 100 μm. ing. In order to realize such a transparent electrode, it is necessary to make the transparent electrode thinner (for example, 100 to 150 nm), to have excellent etching processability, and to have a low sheet resistance.
[0017]
In addition, as the size of the display screen is required to be increased, a sheet resistance is required in order to form a transparent electrode having a dense pattern as described above and to apply a sufficient driving voltage to the liquid crystal. The transparent electrode required a low sheet resistance value of 5Ω / □ or less, preferably 3Ω / □ or less, that is, it had to have high conductivity.
[0018]
However, although the above-mentioned amorphous indium oxide-based material has good etching characteristics because it is amorphous, it has a specific resistance of about 3 to 6 × 10 −4 Ωcm, and thus has a film thickness of 100 to 150 nm. The limit of the sheet resistance of the electrode film was about 40Ω / □. Therefore, an amorphous indium oxide-based material cannot cope with high definition and large size of the display as described above.
[0019]
By the way, the technology of a thin film laminate of a metal film and an indium oxide-based thin film has been known. For example, at the 7th ICVM held in Japan in 1982, a transparent conductive film having a three-layer structure constituted by laminating an ITO film or an indium oxide film on the front and back surfaces of a silver thin film as a heat ray reflective film was proposed. ing. The presence of the silver thin film is for reducing the resistance value, and this transparent conductive film has a sheet resistance of 5Ω / □, and it was expected to be applied to the above-mentioned display device as a transparent electrode by utilizing its high conductivity. However, this technique does not mention the surface roughness of the transparent conductive film.
[0020]
An electrode substrate in which a laminate having a transparent conductive thin film layer to which cerium oxide or titanium oxide is added on both sides of a silver-based conductive thin film layer is provided on a substrate is described in JP-A-9-305126. However, since cerium oxide and titanium oxide are added as high refractive index materials, there is no suggestion of an oxide-based transparent conductive thin film layer other than these.
[0021]
[Problems to be solved by the invention]
As described above, a transparent electrode film that can prevent diffusion seepage and corrosion due to the presence of a grain boundary, has a sheet resistance of 1 to 5 Ω / □ even at a film thickness of 70 to 150 nm, and has a smooth surface. In addition to LCDs, plasma displays and organic EL displays, which are attracting attention as future displays, are also useful for the same reason, but such a transparent electrode film could not be realized by conventional techniques.
[0022]
INDUSTRIAL APPLICABILITY The present invention can prevent diffusion seepage and corrosion due to the presence of grain boundaries, has a sheet resistance of 1 to 5 Ω / □ even at a film thickness of 70 to 150 nm, has excellent surface smoothness, has excellent transparency, and has high definition. Another object is to provide a thin film laminate useful as a large-sized LCD, a plasma display, or a transparent electrode for an organic EL.
[0023]
[Means for Solving the Problems]
The thin film laminate of the present invention has the following features to achieve the above object.
[0024]
That is, the thin film laminate of the present invention comprises two layers of a metal-based conductive thin film layer and an oxide-based transparent conductive thin film layer, or three layers in which the oxide-based transparent conductive thin film layer is provided on both sides of the metal-based conductive thin film layer. A thin film laminate characterized in that an amorphous indium oxide containing at least one selected from tungsten, silicon and germanium is laminated as an oxide-based transparent conductive thin film layer.
[0025]
The metal-based conductive thin film layer is preferably made of at least one of silver, silver-gold based alloy, silver-palladium based alloy, gold, platinum and palladium. The thickness of the metal-based conductive thin film layer is preferably 20 nm or less.
[0026]
The oxide-based transparent conductive thin film layer or the metal-based conductive thin film layer forms the surface of the thin film laminate, and the center line average surface roughness Ra of this surface is preferably 1.5 or less.
[0027]
The thickness of the oxide-based transparent conductive thin film layer is preferably 4 nm or more.
[0028]
When the oxide-based transparent conductive thin film layer is an indium oxide thin film containing tungsten, the tungsten / indium atom ratio is preferably 0.004 to 0.17.
[0029]
When the oxide-based transparent conductive thin film layer is an indium oxide thin film containing silicon, the silicon / indium atom ratio is preferably 0.002 to 0.15.
[0030]
When the oxide-based transparent conductive thin film layer is an indium oxide thin film containing germanium, the germanium / indium atom ratio is preferably 0.002 to 0.15.
[0031]
When the total thickness of the thin film laminate is 70 to 150 nm, the sheet resistance is preferably 5 Ω / □ or less.
[0032]
In another aspect of the present invention, the thin film laminate is provided on a substrate, and a transparent substrate with the thin film laminate is formed. In this case, either the oxide-based transparent conductive thin film layer or the metal-based conductive thin film layer may be in contact with the substrate. The opposite side to the substrate is the surface. The substrate is, for example, a glass plate of a display element, on which the thin film laminate is formed.
[0033]
BEST MODE FOR CARRYING OUT THE INVENTION
Thin film laminate A thin film laminate according to an embodiment of the present invention is an oxide-based transparent conductive thin film represented by an amorphous indium oxide thin film containing at least one element of tungsten, germanium, and silicon. The layer is laminated on one or both sides of at least one metal-based conductive thin film layer of silver, silver-gold-based alloy, silver-palladium-based alloy, gold, platinum, and palladium; The structure is such that one or both sides of the surface of the layer are covered with the oxide-based transparent conductive thin film layer. The thin film laminate is formed on the substrate by film formation to constitute a thin film laminated member, and the metal film or the oxide transparent conductive thin film layer directly in contact with the substrate may be used. The surface opposite to the substrate is the surface.
[0034]
When the overall thickness of the thin film laminate is 70 to 150 nm, a transparent electrode having a sheet resistance of 5 Ω / □ or less can be realized. Since such characteristics can be realized, they are useful as transparent electrodes for display devices such as high-definition LCDs, plasma displays, and organic ELs, and as heat ray shielding films for architectural windows.
[0035]
Oxide-based transparent conductive thin film layer The reason why at least one element of tungsten, germanium, and silicon is contained in indium oxide is as follows. That is, according to an experiment by the inventor, when tungsten is contained, the additive element in the indium oxide thin film which is the oxide-based transparent conductive thin film layer has a tungsten / indium atomic ratio of 0.004 to 0.0096. Yes, if germanium is contained, it is contained at a ratio of 0.002 to 0.17 in germanium / indium atomic ratio, and if silicon is contained, it is 0.002 to 0.15 in silicon / indium atomic ratio. , The indium oxide-based thin film having such a composition tends to have an amorphous structure. If the amount is less than the above range, the completeness of the amorphous material is lost, and if the amount is too large, another crystal phase is precipitated or crystallized easily. In particular, when a sputter film is formed without heating the substrate, a completely amorphous structure-free thin film containing no crystalline phase can be obtained, so that the unevenness of the film surface becomes extremely small. By using an indium oxide-based thin film having such properties on the surface of the thin film laminate, a thin film laminate having a small surface roughness of the film can be obtained.
[0036]
The reason for making the indium oxide thin film amorphous is as follows. That is, in general, the movement of a substance in a thin film frequently occurs along a crystal grain boundary. Indium oxide-based thin films having an amorphous structure have no crystal grain boundaries. Therefore, it is possible to prevent corrosion in which contamination is diffused from the atmosphere through the grain boundaries.
[0037]
In the case of the indium oxide thin film having the above-described structure, a thin film having a completely amorphous structure containing no crystalline phase can be obtained, so that the unevenness of the film surface becomes extremely small and the center line average surface roughness Ra is 1.5 or less. It becomes.
[0038]
Metal-based conductive thin film layer The reason for using at least one of silver, silver-gold based alloy, silver-palladium based alloy, gold, platinum and palladium for the metal-based conductive thin film layer is that The thin film layer has low transmittance in the visible light region, but has a center line average surface roughness Ra of 1.5 or less and extremely small surface irregularities. By setting the thickness to 20 nm or less, a transmittance of 60% or more is obtained. This is because the metal conductive thin film layer can be maintained and the extremely high electrical conductivity of the metal-based conductive thin film layer can be utilized. If the metal-based conductive thin film layer is covered with the indium oxide-based thin film, corrosion due to contact between the metal and the atmosphere can be prevented.
[0039]
Transparent substrate with thin film laminate If the thin film laminate is formed on a glass substrate or the like, a transparent substrate with a thin film laminate such as a liquid crystal display element can be formed as a transparent electrode, for example.
[0040]
【Example】
For the film formation, a DC magnetron sputtering apparatus equipped with two 6-inch φ non-magnetic target cathodes was used. The cathode 1 was provided with a 6-inch φ × 5 mmt indium oxide-based oxide sintered body sputtering target, and the cathode 2 was provided with a 6-inch φ × 5 mmt metal target. A quartz glass substrate was used as the substrate, and the glass substrate could be moved to the opposite surface of each cathode and allowed to stand still, and each film was formed in a stationary opposition.
[0041]
The oxide-based transparent conductive thin film layer was formed under the following conditions. When the distance between the target of the indium oxide-based oxide sintered body and the substrate was 60 mm, and the degree of vacuum in the chamber reached 1 × 10 −4 Pa or less, Ar gas having a purity of 99.9999 mass% was introduced into the chamber. Introduced to a gas pressure of 0.6 Pa, oxygen was introduced into a 1% film forming gas, and DC power of 200 W was applied between the target and the substrate to generate a DC plasma, and the film was formed by sputtering without heating the substrate. Was carried out. The film thickness was controlled by the film formation time.
[0042]
The metal-based conductive thin film layer was formed under the following conditions. When the distance between the target and the substrate was 60 mm and the degree of vacuum in the chamber reached 1 × 10 −4 Pa or less, an Ar gas having a purity of 99.9999 mass% was introduced into the chamber and a gas pressure of 0.6 Pa was applied. A DC power of 100 W was applied between the target and the substrate to generate DC plasma, and the sputtering film formation was performed without heating the substrate. The film thickness was controlled by the film formation time.
[0043]
Under the above conditions, the metal-based conductive thin-film layer and the oxide-based transparent conductive thin-film layer were laminated to produce a thin-film laminate having the following two types of structures.
[0044]
1) substrate / metallic conductive thin film layer / oxide-based transparent conductive thin film layer 2) sheet resistance of substrate / oxide-based transparent conductive thin-film layer / metal-based conductive thin film layer / oxide-based transparent conductive thin-film layered product The light wavelength dependence of the transmittance was measured by a spectrophotometer (manufactured by Hitachi, Ltd.). In addition, the center line average roughness Ra was measured at five locations in an area of 1 mm × 1 mm on the surface of the thin film laminate with an atomic force microscope (NanoScope III, manufactured by Digital Instruments), and the average value was determined. The composition of each film was determined by ICP emission spectrometry and EPMA.
[0045]
(Examples 1 to 13)
A sintered body of indium oxide to which tungsten is added is installed on the cathode 1, and an Ag-Pd-based alloy target (Pd content 1 mass%) is installed on the cathode 2, and a thin film stack of types 1) and 2) is provided. Tables 1 and 2 show examples of the formation of the body.
[0046]
[Table 1]
[Table 2]
As shown in Tables 1 and 2, the thin-film laminate of the present invention has a very low sheet resistance of 2.0 to 4.5 Ω / □ despite the thin total thickness of 70 to 135 nm, The center line average roughness Ra of the surface of the thin film laminate is very small, 1.2 to 1.5 nm, and the surface is flat. Further, the visible light transmittances are all 70% or more, which are satisfactory transmittances when used as a display device.
[0049]
Further, Examples 1 to 13 show examples in which an Ag-Pd-based alloy thin film is used for the metal-based conductive thin-film layer. However, Ag thin films, Ag-Au-based thin films, Ag-Au-Cu-based thin films, Au thin films, and Pt Similar effects were observed when a thin film or a Pd thin film was used.
[0050]
(Examples 14 to 25)
A sintered body target of indium oxide to which silicon was added was installed on the cathode 1, and an Ag-Au-Cu alloy target (Au content 1% by mass, Cu content 0.5% by mass) was installed on the cathode 2. Tables 3 and 4 show examples in which thin film laminates of the types 1) and 2) were formed.
[0051]
[Table 3]
[Table 4]
As shown in Tables 3 and 4, the thin-film laminate of the present invention has a very low sheet resistance of 2.0 to 4.5 Ω / □ despite the thin total thickness of 105 to 135 nm, The center line average roughness Ra of the surface of the thin film laminate is very small, 1.1 to 1.5 nm, and the surface is flat. Further, the visible light transmittances are all 70% or more, which are satisfactory transmittances when used as a display device.
[0054]
Further, in Examples 14 to 25, an example in which an Ag-Au-Cu-based alloy thin film was used for the metal-based conductive thin-film layer was described. Similar effects were observed when a thin film or a Pd thin film was used.
[0055]
(Examples 26 to 36)
A sintered body target of indium oxide to which germanium is added is installed on the cathode 1, and an Ag-Pd-based alloy target (Pd content: 3% by mass) is installed on the cathode 2, and thin film lamination of types 1) and 2) is performed. Tables 5 and 6 show examples in which the body was formed.
[0056]
[Table 5]
[Table 6]
As shown in Tables 5 and 6, the thin film laminate of the present invention has a very low sheet resistance of 2.2 to 4.2 Ω / □ despite the thin total thickness of 105 to 120 nm, The center line average roughness Ra of the surface of the thin film laminate is very small, 1.0 to 1.5 nm, and the surface is flat. Further, the visible light transmittances are all 70% or more, which are satisfactory transmittances when used as a display device.
[0059]
An indium oxide thin film containing germanium also easily becomes a completely amorphous film when formed at room temperature, and has a small surface roughness. Therefore, a thin film laminate having a sheet resistance of 5 Ω / □ or less and an Ra of 1.5 nm or less can be produced by laminating with a metal film such as silver.
[0060]
Further, in Examples 26 to 36, an example in which an Ag-Pd-based thin film was used for the metal-based conductive thin-film layer was described. The same effect was obtained when a Pd thin film was used.
[0061]
Further, similarly to Examples 1 to 36, as the indium oxide-based oxide thin film, even if an indium oxide thin film containing tungsten and tin is used, an indium oxide thin film containing silicon and tin is used, and tungsten and silicon are contained. Similar results were obtained using an indium oxide thin film. In other words, if at least one element of tungsten or silicon is contained in the indium oxide thin film, the film formed at room temperature tends to have an amorphous structure, has a small surface roughness, and has low resistance. The sheet resistance of the thin film laminate was low.
[0062]
Further, in Examples 1 to 36, an example was shown in which an Ag-Pd-based thin film was used for the metal-based conductive thin-film layer. It was confirmed that a similar effect was obtained when a thin film and a Pd thin film were used. The Ag-Au-based thin film, Ag-Au-Cu-based thin film, Ag-based thin film, Au thin film, Pt thin film, and Pd thin film show low resistance of several tens to several hundreds of nΩm like the Ag-Pd thin film. By taking a laminated structure with an indium thin film, a thin film laminate having the same effect can be obtained.
[0063]
Further, in the above embodiment, the same film production was attempted by changing the substrate from a glass substrate to a resin substrate or a resin substrate provided with a silicon oxide film, but the results were the same.
[0064]
(Comparative Examples 1 to 16)
A sintered body target of indium oxide to which tin is added is installed on the cathode 1, and an Ag-Pd-based alloy target (Pd content: 1% by mass) is installed on the cathode 2, and thin film lamination of types 1) and 2) is performed. Table 7 shows an example in which the body was formed.
[0065]
[Table 7]
[Table 8]
As shown in Tables 7 and 8, the sheet resistance of the conventional thin film laminate formed by laminating the Sn-added In 2 O 3 film and the Ag—Pd-based film is as low as 4.3 Ω / □ or less. However, according to the observation with an atomic force microscope, in the thin film laminates of Comparative Examples 1 to 16, the Sn-added In 2 O 3 film was in a mixed state of an amorphous phase and a crystalline phase, and a crystalline phase was present.
[0068]
As a result of holding the thin film laminate in an atmosphere at 85 ° C. and a humidity of 85% for 100 hours and observing the surface, the thin film laminates of Examples 1 to 36 were high in high temperature and humidity resistance without any change in appearance. It was found that Comparative Examples 1 to 16 were discolored and increased in resistance value, and had low high temperature and humidity resistance. Generally, the movement of a substance in a thin film occurs frequently along a grain boundary. The indium oxide-based thin films of Examples 1 to 36 do not have crystal grain boundaries because they have an amorphous structure. If the metal-based conductive thin film layer is covered with such an indium oxide-based thin film, the indium oxide-based thin film has Diffusion and corrosion at grain boundaries due to contact between the metal and the atmosphere can be prevented. On the other hand, since the indium oxide-based thin films of Comparative Examples 1 to 16 contain a crystal phase, grain boundaries exist, and corrosion occurs from the metal-based conductive thin film layer near the grain boundaries of the indium oxide-based thin film. Therefore, it cannot be used for applications in which corrosiveness must be considered.
[0069]
Also, the surface roughness Ra is 2.4 to 3.5 nm, and the surface irregularities are large. Therefore, such a thin film laminate cannot be used for a transparent electrode of an LCD or an organic EL. The protrusions of the crystal phase appear on the surface of the thin film laminate to increase the surface irregularities.
[0070]
(Comparative Examples 17 to 19)
A thin film containing only an indium oxide phase without inserting a metal phase was prepared. Table 9 shows the results of measuring the sheet resistance and the surface roughness by laminating the Sn-added In 2 O 3 film on quartz glass by 115 to 130 nm.
[0071]
[Table 9]
The sheet resistance is as high as 32 to 40 Ω / □, the center line average roughness is as large as 3.2 to 4.5 nm, and the surface irregularities are severe. Therefore, it cannot be used for a high-definition LCD or a transparent electrode for an organic EL.
[0073]
【The invention's effect】
As described in detail above, the thin film laminate of the present invention can prevent diffusion seepage and corrosion due to the presence of crystal grain boundaries, and can be used for applications requiring weather resistance and the like. It has a sheet resistance of 1 to 5 Ω / □ even at up to 150 nm, has excellent surface smoothness, and has excellent transparency, and is useful as a transparent electrode for high-definition or large-sized LCD, plasma display, and organic EL. A transparent electrode made of such a thin film laminate is useful as a transparent electrode for an LCD having a thin and low sheet resistance, which satisfies demands for higher definition and larger size. For the same reason, it is also useful for a transparent electrode for an organic EL, which is attracting attention as a future display, and is extremely valuable industrially.
Claims (8)
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