JP3564294B2 - Thin-film EL panel, method of manufacturing the same, and color EL panel device - Google Patents

Description

注１：○；ダメージなしまたは微小／△；ダメージは有るが発光絵素には影響なし／×；絵素領域減少
注２：駆動電圧は、薄膜ＥＬパネルからの発光が認識され始める直前の印加電圧値。
【００３４】
この実験結果から、上記無添加の硫化亜鉛層１５の膜厚を３０ｎｍ以上に設定すると、エッチング液の第１発光層１４への侵入を防止して第１発光層１４の変質を防止できることが分かる。上記無添加の硫化亜鉛層１５の膜厚が３０ｎｍ未満であると第１発光層１４が損傷を受けることが分かる。
【００３５】
さらに、上記無添加の硫化亜鉛層１５の膜厚を５０ｎｍ以上に設定すると、エッチング液の第１発光層１４への侵入を防止して第１発光層１４の変質をより確実に防止できることが分かる。上記無添加の硫化亜鉛層１５の膜厚が５０ｎｍ未満であると第１発光層１４が損傷を受けることが分かる。
【００３６】
したがって、アルカリ土類金属硫化物を母体材料とする第１発光層１４のエッチングダメージを軽減するためには、第１発光層１４上に積層する無添加の硫化亜鉛層１５の膜厚を３０ｎｍ以上にすることが最小限必要で、５０ｎｍ以上にすればより好ましいことが分かる。
【００３７】
また、実際の薄膜ＥＬパネルの駆動用のドライバーＩＣの駆動電圧限界が約２５０Ｖであるので、表１の駆動電圧値に変調電圧４０〜５０Ｖを加えた電圧を考慮すると、無添加の硫化亜鉛層１５の膜厚が３００ｎｍが限度と考えられる。更に厳しく上記駆動電圧限界を考えると、無添加の硫化亜鉛層１５の膜厚が２００ｎｍが上限となる。
【００３８】
したがって、上記薄膜ＥＬパネルは、上記無添加の硫化亜鉛層１５の膜厚を３０ｎｍ〜３００ｎｍに設定されることが必要で、よりさらに、上記無添加の硫化亜鉛層１５の膜厚を５０ｎｍ〜２００ｎｍに設定するのが好ましいことが分かる。上記無添加の硫化亜鉛層膜厚を３０ｎｍ以上とした薄膜ＥＬパネルは、第１発光層１４（ＳｒＳ：Ｃｅ）の青緑色発光と第２発光層１６（ＺｎＳ：Ｍｎ）の黄橙色発光とが混色された白色発光を呈し、１０００時間の加速エージング（実動換算で５万時間）後も安定な発光特性を維持することができた。
【００３９】
このように、耐薬品性の極めて弱い上記アルカリ土類金属硫化物を母体材料とする上記第１発光層１４と硫化亜鉛を母体材料とする第２発光層１６との間に耐薬品性の有る無添加の硫化亜鉛層１５を挿入している。上記第２発光層１６を形成するときに発生する突沸異物は、上記無添加の硫化亜鉛層１５によって、アルカリ土類金属硫化物を母体材料とする第１発光層１４上に直接接することがない。このように、上記無添加の硫化亜鉛層１５がストッパー層として働くから、電極等を形成するフォトプロセスでエッチャントや洗浄水が第２発光層１６の突沸異物部を介して第１発光層１４に侵入しようとしても、上記第１発光層１４への侵入を防止して、上記第１発光層１４の変質を防ぐことができる。したがって、耐薬品性が極めて弱いアルカリ土類金属硫化物を発光層に用いても、発光層の変質を防止できる。また、上記無添加の硫化亜鉛層１５により第１発光層１４の変質を防ぐことができるので、多種の発光層材料の組み合せが可能となる。
【００４０】
さらに、上記第２発光層１６から上記無添加の硫化亜鉛層１５に、発光センターを形成するＭｎを熱拡散して、その熱拡散効果で上記無添加の硫化亜鉛層１５の領域を発光層として活用できるため、輝度の向上が可能となる。
【００４１】
（第２実施形態）
図２は本発明の第２実施形態の薄膜ＥＬパネルの断面図である。この薄膜ＥＬパネルは、以下の製造工程によって製造される。
【００４２】
まず、ＯＡ−２（日本電気硝子製）等のガラス基板２１上に下部電極２２を形成する。この下部電極２２は、各種の薄膜形成法（スパッタ法、電子ビーム蒸着法、スプレー法等）により、Ｔａ，Ｍｏ，Ｗ等の高融点金属を１００ｎｍ〜４００ｎｍの膜厚に成膜した後、フォトエッチング工程によりストライプ状にパターニングしたものである。
【００４３】
次に、上記下部電極２２上に下部絶縁層２３を形成する。この下部絶縁層２３は、スパッタ法等によりＳｉＯ_２，ＳｉＮ，Ｔａ_２０_５またはＳｒＴｉＯ_３等で２００ｎｍ〜５００ｎｍの膜厚に形成する。
【００４４】
次に、上記下部絶縁層２３上に、例えば電子ビーム蒸着法により、ＣａＳ：Ｅｕペレットを蒸発源として８００ｎｍ〜１５００ｎｍの膜厚の第１発光層２４を形成する。この第１発光層２４はアルカリ土類金属硫化物ＣａＳを母体材料とし、不純物Ｅｕを発光センターとしている。上記第１発光層２４の蒸着時、上記ガラス基板２１の温度を４５０℃〜６５０℃に保持する。また、上記ＣａＳ：Ｅｕペレットは、ＣａＳに０．０５〜０．３ｗｔ％のＥｕＳを添加して焼成したものである。
【００４５】
次に、上記第１発光層２４上に、無添加のＺｎＳペレットを蒸発源として電子ビーム蒸着法により無添加の硫化亜鉛層２５を形成する。上記無添加の硫化亜鉛層２５の蒸着時、上記ガラス基板２１の温度を２００℃〜３００℃に保持する。
【００４６】
次に、上記無添加硫化亜鉛層２５上に３００〜５００ｎｍの膜厚のＺｎＳ：Ｅｒからなる第２発光層２６を電子ビーム蒸着法により形成する。この第２発光層２６は、硫化亜鉛ＺｎＳが母体材料であり、エルビウムＥｒが発光センター(不純物)である。この第２発光層２６の蒸着時もガラス基板２１の温度を２００℃〜３００℃に保持し、ＺｎＳに０．２〜０．６ｗｔ％のＥｒＦ₃を添加して焼成したＺｎＳ：Ｅｒペレットを蒸発源として用いる。
【００４７】
次に、上記第２発光層２６上に下部絶縁層２３と同様のプロセスで上部絶縁層２７を形成する。
【００４８】
そして、上記上部絶縁層２７を形成した後に、第１発光層２４，無添加の硫化亜鉛層２５および第２発光層２６の結晶性を改善するため、真空中で６００〜６５０℃に加熱して、１〜２時間の熱処理を行う。
【００４９】
最後に、上記上部絶縁層２７上に、各種の薄膜形成法（スパッタ法、電子ビーム蒸着法、スプレー法等）によりＩＴＯまたはＺｎＯ：Ａｌ等の１００〜４００ｎｍの膜厚の透明電極を形成して、フォトリソグラフにより上記下部電極２２と直交する方向にストライプ状の透明な上部電極２８を形成する。以上で図２の薄膜ＥＬパネルが完成する。
【００５０】
上記薄膜ＥＬパネルの上部電極２８のエッチングでは、市販のＩＴＯエッチャントまたはＨＢｒ溶液に濃度５０％の硫酸をまぜ合せたものを使用した（ＩＴＯエッチャントまたはＨＢｒ溶液に対する濃度５０％の硫酸の容積比２０〜５０％）。このエッチング溶液に含まれる硫酸は、硫化物系発光層（第２発光層２６）との反応により不変物の硫黄を析出させることにより、エッチング液の浸入に伴う発光層のダメージ拡大を防止する効果がある。
【００５１】
上記無添加の硫化亜鉛層２５がなく、他は上記実施形態と同じ薄膜ＥＬパネルのサンプルを作成すると共に、無添加の硫化亜鉛層２５の膜厚１０ｎｍ， ２０ｎｍ，３０ｎｍ， ５０ｎｍ， １００ｎｍ， ２００ｎｍ， ３００ｎｍおよび５００ｎｍの薄膜ＥＬパネルのサンプルを夫々作成した。そして、上記エッチング液を用いて、複数のサンプルの上部電極２８を同時にパターニングし、上記無添加の硫化亜鉛層２５の膜厚が異なるサンプルにて、ＺｎＳ：Ｅｒの第２発光層２６の形成時に生じた突沸異物部からのエッチング液のしみ込みに起因するダメージ発生の様子を実験により調べた。下表に、実験により得られた薄膜ＥＬパネルの駆動電圧とエッチングダメージの硫化亜鉛の膜厚依存性を示す。
【表２】

備考：○；ダメージなしまたは微小／△；ダメージは有るが発光絵素には影響なし／×；絵素領域減少
注２：駆動電圧は、薄膜ＥＬパネルからの発光が認識され始める直前の印加電圧値。
【００５２】
以上より表１と表２とを比較すると、上記無添加の硫化亜鉛層２５の膜厚を３０ｎｍ以上に設定すると、エッチング液の第１発光層２４への侵入を防止して第１発光層２４の変質を防止できることが分かる。
【００５３】
さらに、上記無添加の硫化亜鉛層２５の膜厚を５０ｎｍ以上に設定すると、エッチング液の第１発光層２４への侵入を防止して第１発光層２４の変質をより確実に防止できることが分かる。
【００５４】
したがって、アルカリ土類金属を母体材料とする第１発光層２４のエッチングダメージを軽減するためには、第１発光層上に積層する無添加の硫化亜鉛層２５の膜厚を３０ｎｍ以上にすることが最低必要で、５０ｎｍ以上にすればより好ましいことが分かる。
【００５５】
また、実際の薄膜ＥＬパネルの駆動用のドライバーＩＣの駆動電圧限界が約２５０Ｖであるので、表２の駆動電圧値に変調電圧４０〜５０Ｖを加えた電圧を考慮すると、無添加の硫化亜鉛層２５の膜厚が２００ｎｍが限度と考えられる。
【００５６】
また、上記第１実施形態で示した上部電極１８のエッチャントである燐酸と比較して、上記第２実施形態における上部電極２８のエッチャントであるＨＢｒ等は硫化物とより強く反応する。したがって、少量のエッチング液が硫化物に侵入しても上記第１発光層２４に大きなダメージが発生するので、上記無添加の硫化亜鉛層２５の膜厚は上記無添加の硫化亜鉛層１５の膜厚よりも厚くする必要がある。したがって、上記薄膜ＥＬパネルは、上記無添加の硫化亜鉛層１５の膜厚を５０ｎｍ〜２００ｎｍに設定するのが好ましいことが分かる。
【００５７】
したがって、上記第２実施形態における上記無添加の硫化亜鉛層２５の膜厚としては５０ｎｍ〜２００ｎｍに設定することが必要である。上記無添加の硫化亜鉛層２５の膜厚を５０ｎｍ以上とした薄膜ＥＬパネルは、ＣａＳ：Ｅｕ第１発光層２４の赤色発光とＺｎＳ：Ｅｒ第２発光層２６の緑青色発光が混色された黄白色発光を呈し、１０００時間の加速エージング（実動換算で５万時間）後も安定な発光特性を維持できた。
【００５８】
このように、耐薬品性の極めて弱い上記アルカリ土類金属硫化物を母体材料とする上記第１発光層２４と硫化亜鉛を母体材料とする第２発光層２６との間に耐薬品性の有る無添加の硫化亜鉛層２５を挿入している。上記第２発光層２６を形成するときに発生する突沸異物は、上記無添加の硫化亜鉛層２５によって、アルカリ土類金属硫化物を母体材料とする第１発光層２４上に直接接することがない。このように、上記無添加の硫化亜鉛層２５がストッパー層として働くから、電極等を形成するフォトプロセスでエッチャントや洗浄水が第２発光層２６の突沸異物部を介して第１発光層２４に侵入しようとしても、上記第１発光層２４への侵入を防止して、上記第１発光層２４の変質を防ぐことができる。したがって、耐薬品性が極めて弱いアルカリ土類金属硫化物を発光層に用いても、発光層の変質を防止できる。また、上記無添加の硫化亜鉛層２５により第１発光層２４の変質を防ぐことができるので、多種の発光層材料の組み合せが可能となる。
【００６０】
（第３実施形態）
図３は本発明の第３実施形態の薄膜ＥＬパネルの断面図である。この薄膜ＥＬパネルは、以下の製造工程によって製造される。
【００６１】
まず、ＯＡ−２（日本電気硝子製）等のガラス基板３１上に下部電極３２を形成する。上記下部電極３２は、各種の薄膜形成法（スパッタ法、電子ビーム蒸着法、スプレー法等）により、ＩＴＯまたはＺｎＯ：Ａｌ等の透明電極を１００ｎｍ〜４００ｎｍの膜厚に成膜した後、フォトエッチング工程によりストライプ状にパターニングしたものである。
【００６２】
次に、上記下部電極３２上に下部絶縁層３３を形成する。上記下部絶縁層３３は、スパッタ法等によりＳｉＯ_２，ＳｉＮ，Ｔａ_２０_５またはＳｒＴｉＯ_３等で２００ｎｍ〜５００ｎｍの膜厚に形成する。
【００６３】
次に、上記下部絶縁層３３上に、例えば電子ビーム蒸着法により、ＳｒＳ：ＣｅＮペレットを蒸発源として８００ｎｍ〜１５００ｎｍの膜厚の第１発光層３４を形成する。この第１発光層３４はアルカリ土類金属硫化物ＳｒＳを母体材料とし、不純物ＣｅＮを発光センターとしている。上記第１発光層３４の蒸着時、上記ガラス基板３１の温度を４５０℃〜６５０℃に保持する。また、上記ＳｒＳ：ＣｅＮペレットは、ＳｒＳに０．０５〜０．３ｗｔ％のＣｅＮを添加して焼成したものである。
【００６４】
次に、上記第１発光層３４上に、無添加のＺｎＳペレットを蒸発源として電子ビーム蒸着法により無添加の硫化亜鉛層３５を形成する。上記硫化亜鉛層３５の蒸着時、上記ガラス基板３１の温度を２００℃〜３００℃に保持する。
【００６５】
次に、上記無添の加硫化亜鉛層３５上には、電子ビーム蒸着法により無添加のＺｎＳペレットを用いてＺｎＳを蒸発させるのと並行して、電子ビーム蒸着法によりＭｎＳペレットを蒸発源として膜中のＭｎ濃度を制御する２源蒸着法によりＺｎＳ：Ｍｎからなる第２発光層３６を積層する。この第２発光層３６は硫化亜鉛ＺｎＳが母体材料であり、マンガンＭｎが発光センター（不純物）である。この第２発光層３６の蒸着時、上記ガラス基板の温度を２００℃〜３００℃に保持し、上記第２発光層３６のトータル膜厚は２５０ｎｍと一定にする。上記第２発光層３６は異なる濃度の２層からなり、成膜初期の領域（０ｎｍ〜５０ｎｍ）のＭｎ濃度は高濃度（０．４〜０．５ｗｔ％）に制御して、残りの領域（５０ｎｍ〜２００ｎｍ）のＭｎ濃度は通常の最適濃度（０２〜０．２５ｗｔ％）となるように制御して第２発光層３６を形成する。
【００６６】
次に、上記第２発光層３６上に、下部絶縁層３３と同様のプロセスで上部絶縁層３７を形成する。
【００６７】
そして、上記上部絶縁層３７を形成した後に、第１発光層３４，無添加の硫化亜鉛層３５および第２発光層３６の結晶性を改善すると共に、および上記第２発光層３６の高濃度のＭｎ領域（０ｎｍ〜５０ｎｍ）から無添加硫化亜鉛層３５へＭｎを熱拡散するため、真空中で６００〜６５０℃に加熱して、１〜２時間の熱処理を行う。
【００６８】
最後に、上記上部絶縁層３７上に１００ｎｍ〜５００ｎｍの膜厚のＡｌ電極を形成して、フォトリソグラフにより下部電極３２と直交する方向にストライプ状の上部電極３８を形成する。以上で図３の薄膜ＥＬパネルが完成する。
【００６９】
上記薄膜ＥＬパネルの上部電極３８のエッチングは、Ａｌ電極のエッチング液として硝酸：水：燐酸を３：２０：２０の割合で混合した溶液に５０％硫酸をまぜ合せたものを使用した（混合溶液に対する濃度５０％の硫酸の容積比２０％）。このエッチング溶液に含まれる硫酸は、硫化物系発光層（第２発光層３６）との反応により不変物の硫黄を析出させることにより、エッチング液の浸入に伴う発光層のダメージ拡大を防止する効果がある。上記の作製条件にて試作した２種類の薄膜ＥＬパネルの発光特性を下表に示す。
【表３】

備考：発光特性は、駆動周波数１００Ｈｚ，パルス幅５０μｓｅｃの交流パルスで測定。
注１：Ｖｔｈは、薄膜ＥＬパネルから３ｃｄ／ｍ^２の発光輝度が認識され始める直前の印加電圧。
注２：Ｌ６０は、Ｖｔｈに変調電圧６０Ｖを加えた印加電圧で駆動した場合の発光輝度。
注３：色度座標は、ＣＩＥ（国際照明委員会）座標のｘ、ｙ値をｘ／ｙで表示した。
【００７０】
この測定結果から、未アニールの薄膜ＥＬパネルにおいては、上記第２発光層３６の結晶性が悪いため、発光輝度が低く、上記第１発光層３４からの輝度比率が強くなるため、色度座標はかなり第１発光層３４の青緑発光よりの値を示す。しかし、上記第２発光層３６内のＭｎ濃度分布を変えた２種類のＺｎＳ：Ｍｎ発光層の違いによる大きな特性差は認められない。一方、真空中アニール前後の特性および上記第２発光層３６のＭｎ濃度分布を変えた２種類のＺｎＳ：Ｍｎの第２発光層３６の違いによる特性を比較すると、上記第２発光層３６からの発光輝度が改善され、積層発光層の輝度比率が変化することが分かる。これは、真空中アニールによりＺｎＳ：Ｍｎ発光層の（１１１）面への配向性が改善されると共に、Ｍｎ発光センターがＺｎの位置に置換して、結晶性が向上したためである。この結果、上記薄膜ＥＬパネルの色度座標ｘ、ｙ値が第２発光層３６の方向に移動して白色発光が得られる。
【００７１】
さらに、上記第２発光層３６の結晶性の改善に伴い、上記第２発光層３６の発光が開始する電界の低電界化が図れ、真空中アニール前と比較して、約２０Ｖの低電圧駆動も実現することができる。
【００７２】
また、上記第２発光層３６の成膜時に、成膜初期の膜厚が５０ｎｍまでの領域のＭｎ濃度を高濃度化した薄膜ＥＬパネルの発光特性を見ると、真空アニール後の上記第２発光層３６の特性改善に伴う発光色の白色化と駆動電圧の低電圧化が同様に実現する。上述のものと上記第２発光層３６の成膜時にＭｎ濃度を均一に添加した薄膜ＥＬパネルとを比較すると、約１０％の発光輝度の改善が達成されている（２３０ｃｄ／ｍ^２から２５５ｃｄ／ｍ^２に改善）。
【００７３】
また、上記アニールによって上記第２発光層３６から上記無添加の硫化亜鉛層にＭｎが熱拡散して、上記無添加の硫化亜鉛層３５の領域を発光層として活用できる。このとき、上記無添加の硫化亜鉛層３５と第２発光層３６との界面近傍の第２発光層３６の部分のＭｎ濃度が第２発光層３６の他の部分よりもＭｎ濃度を高い状態にしているので、無添加の硫化亜鉛層３５へのＭｎの熱拡散量が大きくなり無添加の硫化亜鉛層３５が確実にＭｎを添加された発光層となり、トータルの第２発光層３６の膜厚が厚くなったと同様の効果が得られる。
【００７４】
したがって、上記熱拡散の効果で上記無添加の硫化亜鉛層３５の領域を発光層として活用できるため、薄膜ＥＬパネルにおける発光輝度の向上が可能となる。この熱拡散のとき、上記無添加の硫化亜鉛層３５が第２発光層３６に変化しても、突沸異物が侵入するわけではないので、エッチャントのストッパー層としての働きが低下することはない。しかも上記無添加の発光層３５近傍の第２発光層３６の部分のＭｎ濃度が高いから、上記第２発光層３６の部分からＭｎが無添加の硫化亜鉛層３５へ熱拡散しても、上記第２発光層３６の部分のＭｎ濃度は所定の値に維持でき発光輝度を極めて高くできる。
【００７５】
同様の現象は、上記第２発光層３６のＭｎ濃度を均一に添加した薄膜ＥＬパネルでも生じてるが、拡散したＭｎ濃度が低い場合は、無添加の硫化亜鉛層３５がＺｎＳ：Ｍｎ発光層に変化する確率は低く、輝度の改善効果は小さいと推察される。また、上記無添加の硫化亜鉛層３５上にＭｎ濃度の高濃度領域を形成することにより発光輝度の改善を図った薄膜ＥＬパネルでは、ＳｒＳ：Ｃｅ第１発光層３４の青緑色発光とＺｎＳ：Ｍｎ第２発光層３６の黄橙色が混色された白色発光を呈し、１０００時間の加速エージング（実動換算で５万時間）後も安定な発光特性を維持できた。
【００７６】
このように、耐薬品性の極めて弱い上記アルカリ土類金属硫化物を母体材料とする上記第１発光層３４と硫化亜鉛を母体材料とする第２発光層３６との間に耐薬品性の有る無添加の硫化亜鉛層３５を挿入している。上記第２発光層３６を形成するときに発生する突沸異物は、上記無添加の硫化亜鉛層３５によって、アルカリ土類金属硫化物を母体材料とする第１発光層３４上に直接接することがない。このように、上記無添加の硫化亜鉛層３５がストッパー層として働くから、電極等を形成するフォトプロセスでエッチャントや洗浄水が第２発光層３６の突沸異物部を介して第１発光層３４に侵入しようとしても、上記第１発光層３４への侵入を防止して、第１発光層３４の変質を防ぐことができる。したがって、耐薬品性が極めて弱いアルカリ土類金属硫化物を発光層に用いても、発光層の変質を防止できる。また、上記無添加の硫化亜鉛層３５により第１発光層３４の変質を防ぐことができるので、多種の発光層材料の組み合せが可能となる。
【００７７】
また、上記薄膜ＥＬパネルの製造方法によれば、上記一方の電極を形成する前にアニールを施すことによって、アルカリ土類金属硫化物を母体材料とする第１発光層３４，無添加の硫化亜鉛層３５および第２発光層３６の結晶性を予め改善して、異物部，ピンホール等を通じてのエッチャントや洗浄水が侵入したときのダメージを低減できる。
【００７８】
（第４実施形態）
図４は本発明の第４実施形態のカラーＥＬパネル装置の断面図である。このカラーＥＬパネル装置は、以下の製造工程によって製造される。
【００７９】
まず、ＯＡ−２（日本電気硝子製）等のガラス基板４１上に下部電極４
２を形成する。この下部電極４２は、各種の薄膜形成法（スパッタ法、電子ビーム蒸着法、スプレー法等）により、Ｔａ，Ｍｏ，Ｗ等の高融点金属を１００ｎｍ〜４００ｎｍの膜厚に成膜した後、フォトエッチング工程によりストライプ状にパターニングしたものである。
【００８０】
次に、上記下部電極４２上に下部絶縁層４３を形成する。この下部絶縁層４３は、スパッタ法等によりＳｉＯ_２，ＳｉＮ，Ｔａ_２０_５またはＳｒＴｉＯ_３等で２００ｎｍ〜５００ｎｍの膜厚に形成する。
【００８１】
次に、上記下部絶縁層４３上に、例えば電子ビーム蒸着法により、ＳｒＳ：ＣｅＮペレットを蒸発源として８００ｎｍ〜１５００ｎｍの膜厚の第１発光層４４を形成する。この第１発光層４４はアルカリ土類金属硫化物ＳｒＳを母体材料とし、不純物ＣｅＮを発光センターとしている。この第１発光層４４の蒸着時、上記ガラス基板４１の温度を４５０℃〜６５０℃に保持する。また、上記ＳｒＳ：ＣｅＮペレットは、ＳｒＳに０．０５〜０．３ｗｔ％のＣｅＮを添加して焼成したものである。
【００８２】
次に、上記第１発光層４４上に、無添加のＺｎＳペレットを蒸発源として電子ビーム蒸着法により５０ｎｍ〜１００ｎｍの膜厚の無添加の硫化亜鉛層４５を形成する。上記無添加の硫化亜鉛層４５の蒸着時、上記ガラス基板４１の温度を２００℃〜３００℃に保持する。
【００８３】
次に、上記無添加の硫化亜鉛層４５上に、電子ビーム蒸着法を用いて１５０〜３００ｎｍの膜厚のＺｎＳ：Ｍｎからなる第２発光層４６を形成する。この第２発光層４６は硫化亜鉛ＺｎＳが母体材料であり、マンガンＭｎが発光センター（不純物）である。この電子ビーム蒸着法は、ＺｎＳペレットとＭｎＳペレットを蒸発源として用いて、上記第２発光層４６の膜内のＭｎ濃度を制御する２源蒸着法であって、このときのガラス基板４１の温度を２００℃〜３００℃に保持する。成膜初期の領域（０ｎｍ〜５０ｎｍまたは０ｎｍ〜１００ｎｍ）のＭｎ濃度は高濃度（０．４〜０．５ｗｔ％）にし、残りの領域（５０ｎｍ〜３００ｎｍ）のＭｎ濃度は通常の最適濃度（０．２〜０．２５ｗｔ％）になるように制御して第２発光層４６を形成した。
【００８４】
次に、上記第２発光層４６上に、下部絶縁層４３と同様のプロセスで上部絶縁層４７を形成する。
【００８５】
そして、上記上部絶縁層４７を形成した後に、第１発光層４４，無添加の硫化亜鉛層４５および第２発光層４６の結晶性を改善すると共に、上記第２発光層４６の高濃度のＭｎ領域（０ｎｍ〜５０ｎｍまたは０ｎｍ〜１００ｎｍ）から上記無添加の硫化亜鉛層４５にＭｎを熱拡散するために、真空中で６００〜６５０℃に加熱して、１〜２時間の熱処理を行う。
【００８６】
最後に、上記上部絶縁層４７上に１００ｎｍ〜５００ｎｍの膜厚の透明電極（ＩＴＯまたはＺｎＯ：Ａｌ）を形成して、フォトリソグラフにより下部電極１２と直交する方向にストライプ状の上部電極４８を形成する。
【００８７】
上記構成の薄膜ＥＬパネルの上部電極４８のエッチングでは、市販のＩＴＯエッチャントまたはＨＢｒ溶液に濃度５０％の硫酸をまぜ合せたものを使用した（ＩＴＯエッチャントまたはＨＢｒ溶液に対する濃度５０％の硫酸の容積比２０〜５０％）。このエッチング溶液に含まれる硫酸は、硫化物系発光層（第２発光層４６）との反応により不変物の硫黄を析出させることにより、エッチング液の浸入に伴う発光層のダメージ拡大を防止する効果がある。
【００８８】
上記薄膜ＥＬパネルは、上記下部電極４２と上部電極４８との間に交流電圧を印加することで下部電極４２と上部電極４８との交点が発光する。この第４実施形態では、第１発光層４４（ＳｒＳ：Ｃｅ）の青緑色発光と第２発光層４６（ＺｎＳ：Ｍｎ）の黄橙色発光とが混色された白色発光を呈する。
【００８９】
次に、上記薄膜ＥＬパネルの駆動用の上部電極４８（電極間隔；５０μｍ）から１０μｍの間隔を隔てた位置に、回転塗布法により１０μｍの厚さの光硬化性樹脂に黒色染料を含有させた材料を作製した後、フォトプロセスにより３０μｍ幅で黒色スペーサー５０をストライプ状に形成した。上記黒色スペーサー５０の採用によりコントラストが改善されて視認性の向上が図れる。
【００９０】
そして、ガラス等の透光性基板５５下に赤色フィルターのＲ（ＣＲ−７００１；富士ハント製）・緑色フィルターのＧ（ＣＧ−７００１；富士ハント製）・青色フィルターのＢ（ＣＢ−７００１；富士ハント製）をそれぞれをフォトリソグラフ技術によりストライプ状に形成されたカラーフィルター５４を上記薄膜ＥＬパネルの黒色スペーサ５０上に、配置する。尚、カラーフィルター５４を形成する透光性基板５５には、外部から侵入した水分を捕獲し、薄膜ＥＬパネル内の吸湿剥離を防ぐための吸湿材料５３が充填された枠状の凹部５２（幅３〜１０ｍｍ、深さ０．３〜１ｍｍ）を設けている。
【００９１】
その後、薄膜ＥＬパネルが形成されたガラス基板４１と透光性基板５５をグラスロッド等の間隙材を少量混同したエポキシ樹脂４９等を用いて張り合わせる。
【００９２】
次に、上記ガラス基板４１と透光性基板５５との間（薄膜ＥＬパネルの端部と基板貼り合わせのためのエポキシ樹脂４９との間の空間５１）と上部電極４８とカラーフィルター５４との間（空間５６）に、吸湿材料としてのシリカゲルを混合したシリコンオイルを注入して封止し、オイルシールを行って、カラーＥＬパネル装置が完成する。このとき、貼り合わせる基板間隙幅はカラーＥＬパネル装置の視角依存性に大きな影響を与え、電極間幅の約１／２以下に制御することによって上下左右１６０度の広視野角が確保される。
【００９３】
また、高精細度仕様のカラーＥＬパネル装置では、電極間幅を５０μｍ以下に設定することが多く、特殊な大型パネルの場合を除いて、間隙幅として３０μｍ以下に設定することが望ましい。上記カラーＥＬパネル装置の寿命を決定する要因の大きな１つとして、吸湿剥離の発生に伴う非発光領域の拡大現象により表示部に暗点が発生する。この原因は、前述のパネル作製工程で説明した基板貼り合わせ部を通して侵入した水分が薄膜ＥＬパネルに到達し、薄膜の層間剥離を起こすためである。したがって、侵入する水分を如何に低減し捕獲するかがパネル寿命を左右することになる。この第４実施形態では、侵入した水分を吸湿材料５３で吸収する構造を採用しており、１０万時間以上の環境信頼性が確保できる。上記の工程を経て作製されたカラーＥＬパネル装置は、白色ＥＬ光をＲ・Ｇ・Ｂの各カラーフィルターで分光してＲ・Ｇ・Ｂの光を取り出すことにより、３原色をベースとした多色発光が可能である。そして、実駆動３万時間相当の加速エージングを行った後も、カラーフィルター５４が絶縁破壊等の影響で変質することなく、また、水分の侵入に伴い発生する吸湿剥離も無しに長期間にわたって高い表示品位を維持できた。
【００９４】
このように、耐薬品性の極めて弱い上記アルカリ土類金属硫化物を母体材料とする上記第１発光層４４と硫化亜鉛を母体材料とする第２発光層４６との間に耐薬品性の有る無添加の硫化亜鉛層４５を挿入している。上記第２発光層４６を形成するときに発生する突沸異物は、上記無添加の硫化亜鉛層４５によって、アルカリ土類金属硫化物を母体材料とする第１発光層４４上に直接接することがない。このように、上記無添加の硫化亜鉛層４５がストッパー層として働くから、電極等を形成するフォトプロセスでエッチャントや洗浄水が第２発光層４６の突沸異物部を介して第１発光層４４に侵入しようとしても、上記第１発光層４４への侵入を防止して、第１発光層４４の変質を防ぐことができる。したがって、耐薬品性が極めて弱いアルカリ土類金属硫化物を発光層に用いても、発光層の変質を防止できる。また、上記無添加の硫化亜鉛層４５により第１発光層４４の変質を防ぐことができるので、多種の発光層材料の組み合せが可能となる。
【００９５】
また、上記無添加の硫化亜鉛層４５の膜厚を３０ｎｍ以上に設定すると、エッチング液の第１発光層４４への侵入を防止して第１発光層４４の変質を防止できることが分かる。
【００９６】
さらに、上記無添加の硫化亜鉛層４５の膜厚を５０ｎｍ以上に設定すると、エッチング液の第１発光層４４への侵入を防止して第１発光層４４の変質をより確実に防止できることが分かる。
【００９７】
したがって、アルカリ土類金属硫化物を母体材料とする第１発光層４４のエッチングダメージを軽減するためには、第１発光層４４上に積層する無添加の硫化亜鉛層４５の膜厚を３０ｎｍ以上にすることが最小限必要で、５０ｎｍ以上にすればより好ましいことが分かる。
【００９８】
また、実際の薄膜ＥＬパネルの駆動用のドライバーＩＣの駆動電圧限界が約２５０Ｖであるので、表１の駆動電圧値に変調電圧４０〜５０Ｖを加えた電圧を考慮すると、無添加の硫化亜鉛層４５の膜厚が３００ｎｍが限度と考えられる。更に厳しく上記駆動電圧限界を考えると、無添加の硫化亜鉛層４５の膜厚が２００ｎｍが上限となる。
【００９９】
したがって、上記薄膜ＥＬパネルは、上記無添加の硫化亜鉛層４５の膜厚を３０ｎｍ〜３００ｎｍに設定されることが必要で、よりさらに上記無添加の硫化亜鉛層４５の膜厚を５０ｎｍ〜２００ｎｍに設定するのが好ましい。
【０１００】
さらに、上記第２発光層４６から上記無添加の硫化亜鉛層４５に、発光センターを形成するＭｎを熱拡散して、その熱拡散効果で上記無添加の硫化亜鉛層４５の領域を発光層として活用できるため、輝度の向上が可能となる。
【０１０１】
また、上記アニールによって上記第２発光層４６から上記無添加の硫化亜鉛層にＭｎが熱拡散して、上記無添加の硫化亜鉛層４５の領域を発光層として活用できる。このとき、上記無添加の硫化亜鉛層４５と第２発光層４６との界面近傍の第２発光層４６の部分のＭｎ濃度が第２発光層４６の他の部分よりもＭｎ濃度を高い状態にしているので、無添加の硫化亜鉛層４５へのＭｎの熱拡散量が大きくなり無添加の硫化亜鉛層４５が確実にＭｎを添加された発光層となる。しかも上記無添加の発光層４５近傍の第２発光層４６の部分のＭｎ濃度が高いから、上記第２発光層４６の部分からＭｎが無添加の硫化亜鉛層４５へ熱拡散しても、上記第２発光層４６の部分のＭｎ濃度は所定の値に維持でき発光輝度を極めて高くできる。
【０１０２】
また、上記薄膜ＥＬパネルの製造方法によれば、上記一方の電極を形成する前にアニールを施すことによって、アルカリ土類金属硫化物を母体材料とする第１発光層４４，無添加の硫化亜鉛層４５および第２発光層４６の結晶性を予め改善して、異物部，ピンホール等を通じてのエッチャントや洗浄水が侵入したときのダメージを低減できる。
【０１０３】
また、上記カラーＥＬパネル装置によれば、耐環境性に優れた上記薄膜ＥＬパネルとカラーフィルターとの組み合せによって、長期信頼性に優れたカラーＥＬパネル装置を実現できる。
【０１０４】
上記第１〜第４実施形態では、第１発光層１４，２４，３４，４４の母体材料としてのアルカリ土類金属硫化物にＳｒＳとＣａＳとを用いたが、第１発光層の母体材料に用いるアルカリ土類金属硫化物はこれに限らない。
【０１０５】
また、上記第１〜第４実施形態では、第２発光層１６，２６，３６，４６にＭｎまたはＥｒを添加した硫化亜鉛を用いたが、第２発光層の母体材料である硫化亜鉛に添加される不純物はこれに限らず、発光センターを形成する不純物であればよい。
【０１０６】
【発明の効果】
以上より明らかなように、請求項１の薄膜ＥＬパネルによれば、耐薬品性の極めて弱い上記アルカリ土類金属硫化物を母体材料とする上記第１発光層と硫化亜鉛を母体材料とする第２発光層との間に、耐薬品性の有する無添加の硫化亜鉛層であるストッパー層を挿入しているので、上記第２発光層に付着した突沸異物が第１発光層上に直接接することがなく、したがって、エッチャントや洗浄水が上記第１発光層に侵入するのを防止して、第１発光層の変質を防ぐことができる。
【０１０７】
また、請求項２の薄膜ＥＬパネルによれば、上記無添加の硫化亜鉛層の膜厚を３０ｎｍ〜３００ｎｍに設定しているので、第１発光層へのエッチャント等の侵入を防止でき、かつ、駆動電圧を許容範囲内に抑えることができる。
【０１０８】
また、請求項３の薄膜ＥＬパネルによれば、上記無添加の硫化亜鉛層の膜厚を５０ｎｍ〜２００ｎｍに設定しているので第１発光層へのエッチャント等の侵入をより確実に防止でき、かつ駆動電圧より確実に許容範囲に抑えることができる。
【０１０９】
また、請求項４の薄膜ＥＬパネルによれば、Ｍｎが添加された第２発光層から上記無添加の硫化亜鉛層に、Ｍｎが熱拡散するから、上記無添加の硫化亜鉛層の領域を発光層として活用でき、したがって輝度の向上が可能となる。
【０１１０】
また、請求項６の薄膜ＥＬパネルの製造方法によれば、上記無添加の硫化亜鉛層と上記第２発光層との界面近傍の上記第２発光層の部分のＭｎ濃度が上記第２発光層の他の部分よりもＭｎ濃度が高い状態で、上記第１発光層,上記無添加の硫化亜鉛層および上記第２発光層を積層して、アニールを施しているので、無添加の硫化亜鉛層へのＭｎの熱拡散量が大きくなって無添加の硫化亜鉛層が確実にＭｎを添加された発光層となる一方、上記無添加の発光層近傍の第２発光層の部分のＭｎ濃度が高いから、上記第２発光層の部分からＭｎが無添加の硫化亜鉛層へ熱拡散しても、上記第２発光層の部分のＭｎ濃度は所定の値に維持して発光輝度が低くならない。
【０１１１】
また、請求項７の薄膜ＥＬパネルの製造方法によれば、上記一方の電極を形成する前にアニールを施すから、アルカリ土類金属硫化物を母体材料とする第１発光層,無添加の硫化亜鉛層および第２発光層の結晶性を予め改善して、異物部,ピンホール等を通じてのエッチャントや洗浄水が侵入したときのダメージを低減できる。
【０１１２】
また、請求項８の発明のカラーＥＬパネル装置は、請求項１乃至５のいずれか１つの耐環境性に優れた薄膜ＥＬパネルとカラーフィルターとを組み合せた構造をしているので、長期にわたって信頼性高いカラーＥＬパネル装置を実現することができる。
【図面の簡単な説明】
【図１】図１は、本発明の第１実施形態を示す薄膜ＥＬパネルの構成を示す断面図である。
【図２】図２は、本発明の第２実施形態を示す薄膜ＥＬパネルの構成を示す断面図である。
【図３】図３は、本発明の第３実施形態を示す薄膜ＥＬパネルの構成を示す断面図である。
【図４】図４は、本発明の第４実施実施形態を示すカラーＥＬパネル装置の断面図である。
【図５】図５は、従来の薄膜ＥＬパネルの構成を示す断面図である。
【符号の説明】
１，１１，２１，３１，４１，５５…透光性基板、
２，１２，２２，３２，４２…下部電極、８，１８，２８，３８，４８…上部電極、
３，１３，２３，３３，４３…下部絶縁層、７，１７，２７，３７，４７…上部絶縁層、４，６，１５，２５，３５，４５…無添加の硫化亜鉛層、
５，１４，２４，３４，４４…第１発光層、１６，２６，３６，４６…第２発光層
４９…エポキシ樹脂、５０…スペーサ、５１，５６…空間、
５２…枠状掘り込み溝
５３…吸湿材料、５４…カラーフィルター[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin film EL (electroluminescence) panel, a method of manufacturing the same, and a filter type color EL panel device that performs multicolor display by combining the thin film EL panel with a color filter.
[0002]
[Prior art]
The thin-film EL panel is a self-luminous type display that can be composed entirely of solid-state elements, has high contrast, and has excellent visibility. As described above, the thin film EL panel has characteristics that cannot be obtained by a liquid crystal display device, and thus has been extensively studied, and more recently, research on colorization of the thin film EL panel has been vigorously promoted. .
[0003]
Heretofore, as a color EL panel device using this thin film EL panel, one in which light emitting layers exhibiting three primary colors of red, green, and blue (hereinafter, referred to as R, G, and B) are configured in parallel has been proposed ( See Japanese Patent Publication No. 3-77640). However, in order to adopt this configuration, a high-luminance light-emitting layer exhibiting each of the R, G, and B emission colors is required. However, a light-emitting layer exhibiting sufficient luminance to constitute a color EL panel device is required. Material not found. Therefore, this type of color EL panel device has not been commercialized. Further, as another color EL panel, there is a panel in which white light including three primary colors is separated by using an R, G, and B color filter to extract R, G, and B.
[0004]
By the way, as shown in FIG. 5, a thin-film EL panel, which has been widely researched and developed, has a double insulating structure and a transparent ITO (Indium-Tin-Oxide: An electrode 2 of tin-added indium oxide) or metal is formed, a lower insulating layer 3, a light emitting layer 4, and an upper insulating layer 5 are sequentially laminated, and finally, an upper electrode 6 is formed.
In the thin-film EL panel, when an AC voltage is applied between the lower electrode 2 and the upper electrode 6, the light-emitting layer 4 emits light to enable display. In order to improve the crystallinity of the light emitting layer 4, annealing is performed in a vacuum or in an inert gas after the formation of the light emitting layer 4 or after the formation of the insulating layer 5.
[0005]
The thin film EL panel having the double insulating structure can obtain various luminescent colors by selecting the material of the light emitting layer 4 with the same structure, and a monochrome thin film EL panel using ZnS: Mn as the light emitting layer material has been commercialized. ing. Further, by using a light-emitting layer in which zinc sulfide is used as a base material and a rare-earth compound is added as a light-emitting center to the base material, a light-emitting color based on an inner core transition of a rare-earth element, for example, ZnS: Tb is green, ZnS: Although red and orange colors can be obtained with Sm, white colors and the like can be obtained with ZnS: Pr, but a practical level of luminance has not yet been realized. In order to further improve the properties, alkaline earth metal sulfides are attracting attention as a base material for a new light emitting layer, and blue green is obtained with SrS: Ce and red is obtained with CaS: Eu. Since it has a very high hygroscopicity as compared with zinc sulfide which has been studied, it is easily deteriorated by moisture in the atmosphere. Further, there is a problem that the alkaline earth metal sulfide is easily oxidized. For this reason, when these alkaline earth metal sulfides are used for the light emitting layer, a technique of providing a buffer layer composed of a zinc sulfide layer on both sides of the alkaline earth metal sulfide layer has been widely adopted (Japanese Patent Laid-Open No. Hei 1 (1994)). 241792).
[0006]
In addition, as a light emitting layer for a color EL panel device that separates the above-mentioned white light emission with an RGB color filter, a blue-green SrS: Ce light emitting layer and a yellow-orange ZnS: Mn light emitting layer are laminated. (See Japanese Patent Application Laid-Open No. 62-79986). In this color EL panel device, ZnS: Mn layers are provided on both sides of the SrS: Ce light emitting layer in order to solve the problem of the moisture resistance of the alkaline earth metal described above.
[0007]
[Problems to be solved by the invention]
By the way, when an actual thin-film EL panel was prototyped using the above-mentioned white light-emitting layer, in the patterning of the upper electrode by wet etching, the penetration of an etchant (corrosion liquid) centering on a foreign material part observed on the light-emitting layer was observed. Occurred, and the SrS: Ce light emitting layer was remarkably altered. Also, in the patterning of the upper electrode by dry etching, although varying in degree, etching gas was mixed in from the foreign matter portion, and damage to the light emitting layer was recognized. The foreign matter that causes these deteriorations is that MnS is formed on the evaporation surface of the ZnS: Mn pellet used when forming the ZnS: Mn light emitting layer by a normal electron beam evaporation method, and adheres to the light emitting layer as bumping foreign matter. Difficult to avoid. This bumping phenomenon is not limited to ZnS: Mn, and frequently occurs even when a ZnS pellet to which a rare earth element is added is used, and foreign matter adheres to the light emitting layer. This bumpy foreign substance has a diameter of several μm to several tens μm, and the thickness of the upper insulating layer formed on the bumpy foreign substance is usually about 200 nm to 400 nm, so that the light emitting layer cannot be completely protected. There is. As a result, electrode patterning using a photo process cannot be employed, and is limited to patterning by a mask vapor deposition method. Therefore, it is difficult to achieve high-definition electrodes. Therefore, a promising light emitting layer made of an alkaline earth metal sulfide cannot be effectively used to realize a light emitting layer exhibiting a desired light emitting color by lamination.
[0008]
Therefore, an object of the present invention is to provide a thin film EL that can prevent the intrusion of etchants, moisture, and the like into the light emitting layer and prevent the light emitting layer from being deteriorated even though the alkaline earth metal sulfide is used for the light emitting layer. An object of the present invention is to provide a panel, a manufacturing method thereof, and a color EL panel device.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a thin film EL panel according to claim 1, wherein a plurality of light emitting layers are sandwiched between insulating layers, electrodes are provided on the surfaces of these insulating layers, and the thin film EL panel is used for a color EL panel device of a filter system. Wherein the plurality of light emitting layers are a first light emitting layer to which impurities are added using alkaline earth metal sulfide as a base material and a second light emitting layer to which impurities are added using zinc sulfide as a base material; A stopper layer for preventing an etchant from entering the first light emitting layer is inserted between the first light emitting layer and the second light emitting layer; ,Up The stopper layer is a zinc sulfide layer to which no additive is added.
[0010]
Claims above 1 According to the thin-film EL panel of the above, the chemical resistance between the first light emitting layer using the alkaline earth metal sulfide as the base material and the second light emitting layer using zinc sulfide as the base material is extremely weak. An additive free zinc sulfide layer is inserted. The bumping foreign matter generated when the second light emitting layer is formed does not come into direct contact with the first light emitting layer containing alkaline earth metal sulfide as a base material by the non-added zinc sulfide layer. As described above, since the non-added zinc sulfide layer functions as a stopper layer, the etchant or the cleaning water tries to enter the first light emitting layer through the bumping foreign matter portion of the second light emitting layer in the photo process of forming an electrode or the like. Also, it is possible to prevent intrusion into the first light emitting layer and prevent the first light emitting layer from being deteriorated. Therefore, even if the alkaline earth metal sulfide having extremely low chemical resistance is used for the light emitting layer, the light emitting layer can be prevented from being deteriorated. In addition, since the first light emitting layer can be prevented from being deteriorated by the non-added zinc sulfide layer, various kinds of light emitting layer materials can be combined.
[0011]
Claims 2 Thin-film EL panel 1 Wherein the thickness of the non-added zinc sulfide layer is in the range of 30 nm to 300 nm.
[0012]
Experiments have confirmed that when the thickness of the non-added zinc sulfide layer is set to 30 nm or more, it is possible to prevent the etchant from entering the first light emitting layer and prevent the first light emitting layer from being deteriorated. It was found that the first light emitting layer was damaged when the thickness of the non-added zinc sulfide layer was less than 30 nm. Further, it was found that when the thickness of the non-added zinc sulfide layer was set to 300 nm or less, the increase in the driving voltage of the thin-film EL panel due to the insertion of the non-added zinc sulfide layer could be suppressed to an allowable range. Further, it was found that when the thickness of the non-added zinc sulfide layer exceeded 300 nm, the driving voltage of the thin film EL panel was exceeded. Therefore, the claims 2 In the thin film EL panel described above, the thickness of the non-added zinc sulfide layer is set to 30 nm to 300 nm.
[0013]
Claims 3 Thin-film EL panel 2 The thin film EL panel of the above, wherein the thickness of the non-added zinc sulfide layer is in the range of 50 nm to 200 nm.
[0014]
It was confirmed by experiments that when the thickness of the non-added zinc sulfide layer was set to 50 nm or more, it was possible to prevent the etchant from entering the first light emitting layer and more reliably prevent the first light emitting layer from being altered. It was found that if the thickness of the non-added zinc sulfide layer was less than 50 nm, the first light emitting layer was damaged. Further, it was found that when the thickness of the non-added zinc sulfide layer was set to 200 nm or less, the increase in the driving voltage of the thin-film EL panel due to the insertion of the non-added zinc sulfide layer could be suppressed to an allowable range. Further, it was found that when the thickness of the non-added zinc sulfide layer exceeded 200 nm, the driving voltage of the thin film EL panel was exceeded. Therefore, the claims 3 In the thin film EL panel described above, the thickness of the zinc sulfide layer without addition is set to 50 nm to 200 nm.
[0015]
Claims 4 Thin-film EL panel 1 In the above-mentioned thin-film EL panel, the first light emitting layer is made of SrS as a base material, and the second light emitting layer is made of zinc sulfide to which Mn is added.
Claims above 4 According to this thin film EL panel, Mn forming a light emission center is thermally diffused from the second light emitting layer to the non-added zinc sulfide layer, and the region of the non-added zinc sulfide layer is diffused by the heat diffusion effect. Since it can be used as a light emitting layer, luminance can be improved.
[0016]
Claims 5 The method for manufacturing a thin film EL panel according to the above is a method for manufacturing a thin film EL panel used for a filter type color EL panel device, wherein a step of forming a lower electrode on a substrate and a step of forming a lower insulating layer on the lower electrode Forming a first light emitting layer to which an impurity is added using an alkaline earth metal sulfide as a base material on the lower insulating layer; and an etchant penetrates the first light emitting layer on the first light emitting layer. A step of forming a stopper layer for preventing the formation of the second light-emitting layer, a step of forming a second light-emitting layer to which impurities are added using zinc sulfide as a base material by an electron beam evaporation method, and a step of forming a second light-emitting layer on the stopper layer. The method is characterized by including a step of forming an upper insulating layer and a step of forming an upper electrode patterned by etching on the upper insulating layer.
Claims 6 For manufacturing a thin-film EL panel 4 A first step of sequentially laminating the first light-emitting layer, the non-added zinc sulfide layer, and the second light-emitting layer; A second step of diffusing Mn of the second light emitting layer into a part of the non-added zinc sulfide layer by performing annealing on the zinc layer and the second light emitting layer. The portion of the second light emitting layer near the interface between the zinc sulfide layer with no addition and the second light emitting layer has a higher Mn concentration than other portions of the second light emitting layer. .
[0017]
Claims above 6 According to the method of manufacturing a thin-film EL panel described above, Mn is thermally diffused from the second light-emitting layer to the non-added zinc sulfide layer by the annealing, and the region of the non-added zinc sulfide layer can be used as a light-emitting layer. . At this time, since the Mn concentration of the portion of the second light emitting layer near the interface between the non-added zinc sulfide layer and the second light emitting layer is higher than the other portions of the second light emitting layer, The thermal diffusion amount of Mn into the non-added zinc sulfide layer increases, and the non-added zinc sulfide layer surely becomes a light emitting layer to which Mn is added. In addition, since the Mn concentration in the portion of the second light emitting layer near the light emitting layer with no addition is high, even if Mn is thermally diffused from the portion of the second light emitting layer into the zinc sulfide layer with no addition, the second light emission is suppressed. The Mn concentration in the layer portion can be maintained at a predetermined value, and the emission luminance of the second light emitting layer can be increased.
[0018]
Claims 7 For manufacturing a thin-film EL panel 6 In the method for manufacturing a thin film EL panel of the above, the electrode, the insulating layer, the first light emitting layer, the non-added zinc sulfide layer, the second light emitting layer, and the insulating layer are sequentially laminated and annealed, and then the other is formed. It is characterized in that electrodes are formed.
[0019]
Claims above 7 According to the method of manufacturing a thin film EL panel of the above, by performing annealing before forming the one electrode, the first light-emitting layer having an alkaline earth metal sulfide as a base material, the additive-free zinc sulfide layer, and the (2) By improving the crystallinity of the light emitting layer in advance, it is possible to reduce damage when an etchant or cleaning water enters through a foreign substance portion, a pinhole, or the like.
[0020]
Claims 8 The color EL panel device of claims 1 to 4 Characterized in that it has a structure in which any one of the thin-film EL panels and a color filter are combined.
[0021]
Claims above 8 According to the color EL panel device described above, a color EL panel device excellent in long-term reliability can be realized by combining the above-described thin film EL panel excellent in environmental resistance and a color filter.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a thin film EL panel, a method of manufacturing the same, and a color EL panel device of the present invention will be described in detail with reference to the illustrated embodiments.
[0023]
(1st Embodiment)
FIG. 1 is a sectional view of a thin-film EL panel according to a first embodiment of the present invention. This thin film EL panel is manufactured by the following manufacturing steps.
[0024]
First, a lower electrode 12 is formed on a glass substrate 11 such as OA-2 (manufactured by Nippon Electric Glass). The lower electrode 12 is formed by forming a transparent electrode of ITO or ZnO: Al into a film having a thickness of 100 nm to 400 nm by various thin film forming methods (sputtering method, electron beam evaporation method, spraying method, etc.), and then performing photoetching. It is patterned in stripes by the process.
[0025]
Next, a lower insulating layer 13 is formed on the lower electrode 12. This lower insulating layer 13 is made of SiO 2 by sputtering or the like. ₂ , SiN, Ta ₂ 0 ₅ Or SrTiO ₃ It is formed to a thickness of 200 nm to 500 nm by the above method.
[0026]
Next, the first light emitting layer 14 having a thickness of 800 nm to 1500 nm is formed on the lower insulating layer 13 by using, for example, an SrS: CeN pellet as an evaporation source by an electron beam evaporation method. The first light emitting layer 14 uses an alkaline earth metal sulfide SrS as a base material and an impurity CeN as a light emission center. During the deposition of the first light emitting layer 14, the temperature of the glass substrate 11 is maintained at 450 ° C to 650 ° C. The SrS: CeN pellets are obtained by adding 0.05 to 0.3 wt% of CeN to SrS and firing.
[0027]
Next, a zinc sulfide layer 15 with no addition is formed on the first light emitting layer 14. The non-added zinc sulfide layer 15 is formed by electron beam evaporation using the non-added ZnS pellet as an evaporation source. During the deposition of the zinc sulfide layer 15, the temperature of the glass substrate 11 is maintained at 200 ° C to 300 ° C.
[0028]
Next, a second light emitting layer 16 of ZnS: Mn having a thickness of 300 nm is formed on the non-added zinc sulfide layer 15 by an electron beam evaporation method. In the second light emitting layer 16, zinc sulfide ZnS is a base material, and manganese Mn is a light emission center (impurity). During the deposition of the second light emitting layer 16, the temperature of the glass substrate 11 is maintained at 200 ° C. to 300 ° C., and ZnS: Mn pellets baked by adding 0.2 to 0.6 wt% Mn to ZnS are evaporated. Use as a source.
[0029]
Next, an upper insulating layer 17 is formed on the second light emitting layer 16 by a process similar to that for the lower insulating layer 13.
[0030]
Then, after the upper insulating layer 17 is formed, in order to improve the crystallinity of the first light-emitting layer 14, the non-doped zinc sulfide layer 15, and the second light-emitting layer 16, the first light-emitting layer 14 is heated to 600 to 650 ° C. in vacuum, Heat treatment is performed for 1 to 2 hours.
[0031]
Finally, an Al electrode having a thickness of 100 nm to 500 nm is formed on the upper insulating layer 17, and a stripe-shaped upper electrode 18 is formed by photolithography in a direction orthogonal to the lower electrode 12. Thus, the thin-film EL panel of FIG. 1 is completed.
[0032]
In the etching of the upper electrode 18 of the thin film EL panel, a solution obtained by mixing nitric acid: water: phosphoric acid at a ratio of 3:20:20 with sulfuric acid having a concentration of 50% was used as an etching solution for the Al electrode ( 20% by volume of 50% strength sulfuric acid to the mixed solution). Sulfuric acid contained in the etching solution reacts with the sulfide-based light-emitting layer (second light-emitting layer 16) to precipitate invariant sulfur, thereby preventing the damage of the light-emitting layer from being damaged by the intrusion of the etchant. There is.
[0033]
A sample of the same thin film EL panel as that of the above embodiment was prepared without the above-described additive-free zinc sulfide layer 15, and the thickness of the additive-free zinc sulfide layer 15 was 10 nm, 20 nm, 30 nm, 50 nm, 100 nm, 200 nm, Samples of 300 nm and 500 nm thin film EL panels were made, respectively. Then, the upper electrodes 18 of a plurality of samples are simultaneously patterned using the above-mentioned etching solution. The appearance of damage caused by the penetration of the etchant from the generated bumping foreign matter was examined by experiments. The following table shows the dependence of the driving voltage and etching damage of the thin film EL panel on the thickness of the zinc sulfide film obtained by the experiment.
[Table 1]

Note 1: ○: No damage or minute / △; Damage is present but no effect on luminescent picture elements / ×; Picture area reduced
Note 2: The drive voltage is an applied voltage value immediately before light emission from the thin-film EL panel starts to be recognized.
[0034]
From the experimental results, it can be seen that when the thickness of the non-added zinc sulfide layer 15 is set to 30 nm or more, it is possible to prevent the etchant from entering the first light emitting layer 14 and prevent the first light emitting layer 14 from being altered. . It can be seen that the first light emitting layer 14 is damaged when the thickness of the non-added zinc sulfide layer 15 is less than 30 nm.
[0035]
Furthermore, when the thickness of the non-added zinc sulfide layer 15 is set to 50 nm or more, it is found that the etchant can be prevented from entering the first light emitting layer 14 and the first light emitting layer 14 can be more reliably prevented from being deteriorated. . It is understood that if the thickness of the non-added zinc sulfide layer 15 is less than 50 nm, the first light emitting layer 14 is damaged.
[0036]
Therefore, in order to reduce the etching damage of the first light emitting layer 14 having the alkaline earth metal sulfide as a base material, the thickness of the non-added zinc sulfide layer 15 laminated on the first light emitting layer 14 should be 30 nm or more. It is understood that it is necessary to minimize the thickness, and it is more preferable to set the thickness to 50 nm or more.
[0037]
Further, since the driving voltage limit of the driver IC for actually driving the thin-film EL panel is about 250 V, considering the voltage obtained by adding the modulation voltage of 40 to 50 V to the driving voltage value in Table 1, the zinc sulfide layer having no additive is used. It is considered that the film thickness of No. 15 is 300 nm. Considering the drive voltage limit more strictly, the upper limit is 200 nm in thickness of the zinc sulfide layer 15 with no addition.
[0038]
Therefore, in the thin-film EL panel, it is necessary that the thickness of the non-added zinc sulfide layer 15 is set to 30 nm to 300 nm, and further, the thickness of the non-added zinc sulfide layer 15 is set to 50 nm to 200 nm. It can be seen that it is preferable to set In the thin-film EL panel in which the thickness of the non-added zinc sulfide layer is 30 nm or more, the blue light emission of the first light emitting layer 14 (SrS: Ce) and the yellow orange light emission of the second light emitting layer 16 (ZnS: Mn) are obtained. It exhibited mixed white light emission, and could maintain stable light emission characteristics even after accelerated aging for 1000 hours (50,000 hours in actual operation).
[0039]
As described above, there is chemical resistance between the first light emitting layer 14 using the alkaline earth metal sulfide as a base material and the second light emitting layer 16 using zinc sulfide as a base material. An additive-free zinc sulfide layer 15 is inserted. The bumping foreign matter generated when the second light emitting layer 16 is formed does not come into direct contact with the first light emitting layer 14 having an alkaline earth metal sulfide as a base material by the non-added zinc sulfide layer 15. . As described above, since the non-added zinc sulfide layer 15 functions as a stopper layer, an etchant or cleaning water is applied to the first light emitting layer 14 via the bumping foreign matter portion of the second light emitting layer 16 by a photo process for forming an electrode or the like. Even if an attempt is made to penetrate, the first light emitting layer 14 can be prevented from penetrating, thereby preventing the first light emitting layer 14 from being altered. Therefore, even if the alkaline earth metal sulfide having extremely low chemical resistance is used for the light emitting layer, the light emitting layer can be prevented from being deteriorated. In addition, since the first light emitting layer 14 can be prevented from being deteriorated by the non-added zinc sulfide layer 15, various kinds of light emitting layer materials can be combined.
[0040]
Further, Mn forming a light emission center is thermally diffused from the second light emitting layer 16 to the non-added zinc sulfide layer 15, and the region of the non-added zinc sulfide layer 15 is used as a light emitting layer by the heat diffusion effect. Since it can be used, the luminance can be improved.
[0041]
(2nd Embodiment)
FIG. 2 is a sectional view of a thin-film EL panel according to a second embodiment of the present invention. This thin film EL panel is manufactured by the following manufacturing steps.
[0042]
First, a lower electrode 22 is formed on a glass substrate 21 such as OA-2 (manufactured by Nippon Electric Glass). The lower electrode 22 is formed by depositing a high melting point metal such as Ta, Mo, W, etc. to a thickness of 100 to 400 nm by various thin film forming methods (sputtering method, electron beam evaporation method, spraying method, etc.), It is patterned into a stripe by an etching process.
[0043]
Next, a lower insulating layer 23 is formed on the lower electrode 22. This lower insulating layer 23 is made of SiO 2 by sputtering or the like. ₂ , SiN, Ta ₂ 0 ₅ Or SrTiO ₃ It is formed to a thickness of 200 nm to 500 nm by the above method.
[0044]
Next, the first light emitting layer 24 having a thickness of 800 nm to 1500 nm is formed on the lower insulating layer 23 by using, for example, an electron beam evaporation method with the CaS: Eu pellet as an evaporation source. The first light emitting layer 24 uses alkaline earth metal sulfide CaS as a base material and an impurity Eu as a light emitting center. During the deposition of the first light emitting layer 24, the temperature of the glass substrate 21 is maintained at 450 ° C. to 650 ° C. The CaS: Eu pellets are obtained by adding 0.05 to 0.3 wt% of EuS to CaS and firing.
[0045]
Next, a non-added zinc sulfide layer 25 is formed on the first light-emitting layer 24 by electron beam evaporation using the non-added ZnS pellet as an evaporation source. During the deposition of the non-added zinc sulfide layer 25, the temperature of the glass substrate 21 is maintained at 200 ° C to 300 ° C.
[0046]
Next, ZnS having a thickness of 300 to 500 nm is formed on the non-added zinc sulfide layer 25. Er Is formed by an electron beam evaporation method. The second light emitting layer 26 is made of zinc sulfide ZnS as a base material, Erbium Er Is a light emission center (impurity). During the deposition of the second light emitting layer 26, the temperature of the glass substrate 21 is maintained at 200 ° C. to 300 ° C., and 0.2 to 0.6 wt% of ErF is added to ZnS. _Three Is used as the evaporation source.
[0047]
Next, an upper insulating layer 27 is formed on the second light emitting layer 26 by a process similar to that of the lower insulating layer 23.
[0048]
Then, after the upper insulating layer 27 is formed, in order to improve the crystallinity of the first light emitting layer 24, the zinc sulfide layer 25 with no addition, and the second light emitting layer 26, the first light emitting layer 24 is heated to 600 to 650 ° C. in a vacuum. For 1 to 2 hours.
[0049]
Finally, a transparent electrode having a thickness of 100 to 400 nm, such as ITO or ZnO: Al, is formed on the upper insulating layer 27 by various thin film forming methods (sputtering method, electron beam evaporation method, spraying method, etc.). Then, a transparent transparent upper electrode 28 is formed in a direction orthogonal to the lower electrode 22 by photolithography. Thus, the thin-film EL panel of FIG. 2 is completed.
[0050]
In etching the upper electrode 28 of the thin-film EL panel, a commercially available ITO etchant or HBr solution mixed with 50% sulfuric acid was used (a volume ratio of 50% sulfuric acid to ITO etchant or HBr solution of 20 to 20%). 50%). The sulfuric acid contained in this etching solution precipitates invariant sulfur by reacting with the sulfide-based light-emitting layer (second light-emitting layer 26), thereby preventing the light-emitting layer from being damaged by the infiltration of the etchant. There is.
[0051]
A sample of the same thin film EL panel as that of the above embodiment was prepared without the above-described additive-free zinc sulfide layer 25, and the thickness of the additive-free zinc sulfide layer 25 was 10 nm, 20 nm, 30 nm, 50 nm, 100 nm, 200 nm, Samples of 300 nm and 500 nm thin film EL panels were made, respectively. Then, the upper electrodes 28 of a plurality of samples are simultaneously patterned using the above-mentioned etching solution, and the samples having different thicknesses of the non-added zinc sulfide layer 25 are used for forming the second light emitting layer 26 of ZnS: Er. The appearance of damage caused by the penetration of the etchant from the generated bumping foreign matter was examined by experiments. The following table shows the dependence of the driving voltage and etching damage of the thin film EL panel on the thickness of the zinc sulfide film obtained by the experiment.
[Table 2]

Remarks: ○; no damage or minute / △; damage is present but has no effect on luminescent picture elements / ×; picture element area is reduced
Note 2: The drive voltage is an applied voltage value immediately before light emission from the thin-film EL panel starts to be recognized.
[0052]
Comparing Tables 1 and 2 above, when the thickness of the non-added zinc sulfide layer 25 is set to 30 nm or more, the first luminescent layer 24 is prevented by preventing the etchant from entering the first luminescent layer 24. It can be seen that the deterioration of the material can be prevented.
[0053]
Furthermore, when the thickness of the non-added zinc sulfide layer 25 is set to 50 nm or more, it is found that the etchant can be prevented from entering the first light emitting layer 24 and the first light emitting layer 24 can be more reliably prevented from being deteriorated. .
[0054]
Therefore, in order to reduce the etching damage of the first light emitting layer 24 made of an alkaline earth metal as a base material, the thickness of the non-added zinc sulfide layer 25 laminated on the first light emitting layer should be 30 nm or more. It is understood that the minimum is necessary, and it is more preferable if the thickness is 50 nm or more.
[0055]
Further, since the driving voltage limit of the driver IC for actually driving the thin-film EL panel is about 250 V, considering the voltage obtained by adding the modulation voltage of 40 to 50 V to the driving voltage value shown in Table 2, the zinc sulfide layer having no additive is used. It is considered that the film thickness of 25 is limited to 200 nm.
[0056]
Further, as compared with the phosphoric acid which is the etchant of the upper electrode 18 shown in the first embodiment, the HBr or the like which is the etchant of the upper electrode 28 in the second embodiment reacts more strongly with the sulfide. Therefore, even if a small amount of etching solution enters the sulfide, the first light emitting layer 24 is seriously damaged, and the thickness of the non-added zinc sulfide layer 25 is equal to the thickness of the non-added zinc sulfide layer 15. It must be thicker than thick. Therefore, it can be seen that in the thin film EL panel, the thickness of the non-added zinc sulfide layer 15 is preferably set to 50 nm to 200 nm.
[0057]
Therefore, the thickness of the non-added zinc sulfide layer 25 in the second embodiment needs to be set to 50 nm to 200 nm. The thin-film EL panel in which the thickness of the non-added zinc sulfide layer 25 is 50 nm or more is a yellow in which the red light emission of the CaS: Eu first light emitting layer 24 and the green-blue light emission of the ZnS: Er second light emitting layer 26 are mixed. It emitted white light, and was able to maintain stable light-emitting characteristics even after accelerated aging for 1,000 hours (50,000 hours in actual operation).
[0058]
As described above, there is chemical resistance between the first light emitting layer 24 using the alkaline earth metal sulfide as the base material and the second light emitting layer 26 using zinc sulfide as the base material, which have extremely low chemical resistance. An additive-free zinc sulfide layer 25 is inserted. The bumping foreign matter generated when the second light emitting layer 26 is formed does not come into direct contact with the first light emitting layer 24 whose base material is an alkaline earth metal sulfide by the non-added zinc sulfide layer 25. . As described above, since the non-added zinc sulfide layer 25 functions as a stopper layer, an etchant or cleaning water is applied to the first light emitting layer 24 via the bumping foreign matter portion of the second light emitting layer 26 by a photo process for forming an electrode or the like. Even if an attempt is made to invade, the intrusion into the first light emitting layer 24 can be prevented, so that the first light emitting layer 24 can be prevented from being deteriorated. Therefore, even if the alkaline earth metal sulfide having extremely low chemical resistance is used for the light emitting layer, the light emitting layer can be prevented from being deteriorated. In addition, since the non-added zinc sulfide layer 25 can prevent the first light-emitting layer 24 from being deteriorated, various kinds of light-emitting layer materials can be combined.
[0060]
(Third embodiment)
FIG. 3 is a sectional view of a thin-film EL panel according to a third embodiment of the present invention. This thin film EL panel is manufactured by the following manufacturing steps.
[0061]
First, the lower electrode 32 is formed on a glass substrate 31 such as OA-2 (manufactured by Nippon Electric Glass). The lower electrode 32 is formed by forming a transparent electrode such as ITO or ZnO: Al to a thickness of 100 nm to 400 nm by various thin film forming methods (sputtering method, electron beam evaporation method, spraying method, etc.), and then performing photoetching. It is patterned in stripes by the process.
[0062]
Next, a lower insulating layer 33 is formed on the lower electrode 32. The lower insulating layer 33 is made of SiO 2 by sputtering or the like. ₂ , SiN, Ta ₂ 0 ₅ Or SrTiO ₃ It is formed to a thickness of 200 nm to 500 nm by the above method.
[0063]
Next, the first light emitting layer 34 having a thickness of 800 nm to 1500 nm is formed on the lower insulating layer 33 by using, for example, an SrS: CeN pellet as an evaporation source by an electron beam evaporation method. The first light-emitting layer 34 uses alkaline earth metal sulfide SrS as a base material and impurity CeN as a light-emission center. During the deposition of the first light emitting layer 34, the temperature of the glass substrate 31 is maintained at 450 ° C. to 650 ° C. The SrS: CeN pellets are obtained by adding 0.05 to 0.3 wt% of CeN to SrS and firing.
[0064]
Next, a non-added zinc sulfide layer 35 is formed on the first light emitting layer 34 by electron beam evaporation using the non-added ZnS pellet as an evaporation source. During the deposition of the zinc sulfide layer 35, the temperature of the glass substrate 31 is maintained at 200 ° C to 300 ° C.
[0065]
Next, on the non-added zinc vulcanized layer 35, the MnS pellet was used as an evaporation source by electron beam evaporation in parallel with the evaporation of ZnS using the unadded ZnS pellet by electron beam evaporation. The second light emitting layer 36 made of ZnS: Mn is laminated by a two-source vapor deposition method for controlling the Mn concentration in the film. In the second light emitting layer 36, zinc sulfide ZnS is a base material, and manganese Mn is a light emitting center (impurity). During the deposition of the second light emitting layer 36, the temperature of the glass substrate is maintained at 200 ° C. to 300 ° C., and the total film thickness of the second light emitting layer 36 is fixed at 250 nm. The second light emitting layer 36 is composed of two layers having different concentrations, and the Mn concentration in the initial region (0 nm to 50 nm) is controlled to a high concentration (0.4 to 0.5 wt%), and the remaining region ( The second light emitting layer 36 is formed by controlling the Mn concentration (50 nm to 200 nm) to be a normal optimum concentration (02 to 0.25 wt%).
[0066]
Next, an upper insulating layer 37 is formed on the second light emitting layer 36 by a process similar to that for the lower insulating layer 33.
[0067]
After the formation of the upper insulating layer 37, the crystallinity of the first light emitting layer 34, the non-added zinc sulfide layer 35 and the second light emitting layer 36 is improved, and the high concentration of the second light emitting layer 36 is improved. In order to thermally diffuse Mn from the Mn region (0 nm to 50 nm) to the additive-free zinc sulfide layer 35, heat treatment is performed at 600 to 650 ° C. in a vacuum to perform heat treatment for 1 to 2 hours.
[0068]
Finally, an Al electrode having a thickness of 100 nm to 500 nm is formed on the upper insulating layer 37, and a stripe-shaped upper electrode 38 is formed by photolithography in a direction orthogonal to the lower electrode 32. Thus, the thin-film EL panel of FIG. 3 is completed.
[0069]
For the etching of the upper electrode 38 of the thin film EL panel, a mixture of nitric acid: water: phosphoric acid at a ratio of 3:20:20 and 50% sulfuric acid was used as an etching solution for the Al electrode (mixed solution). 20% by volume of sulfuric acid having a concentration of 50% based on The sulfuric acid contained in the etching solution precipitates invariant sulfur by reacting with the sulfide-based light-emitting layer (second light-emitting layer 36), thereby preventing the light-emitting layer from being damaged by the infiltration of the etchant. There is. The light emission characteristics of the two types of thin-film EL panels prototyped under the above production conditions are shown in the table below.
[Table 3]

Remarks: Light emission characteristics are measured with an AC pulse having a driving frequency of 100 Hz and a pulse width of 50 μsec.
Note 1: Vth is 3 cd / m from thin film EL panel ² The applied voltage immediately before the light emission luminance starts to be recognized.
Note 2: L60 is the light emission luminance when driven by an applied voltage obtained by adding a modulation voltage of 60 V to Vth.
Note 3: The chromaticity coordinates are represented by x / y of x and y values of CIE (International Commission on Illumination).
[0070]
From this measurement result, in the unannealed thin film EL panel, the luminous luminance is low because the crystallinity of the second light emitting layer 36 is poor, and the luminance ratio from the first light emitting layer 34 is high. Indicates a value considerably higher than the blue-green light emission of the first light emitting layer 34. However, a large difference in characteristics due to the difference between the two types of ZnS: Mn light emitting layers having different Mn concentration distributions in the second light emitting layer 36 is not recognized. On the other hand, a comparison between the characteristics before and after annealing in a vacuum and the characteristics of the two types of ZnS: Mn with different Mn concentration distributions of the second light emitting layer 36 due to the difference between the second light emitting layers 36 shows that It can be seen that the light emission luminance is improved and the luminance ratio of the laminated light emitting layer changes. This is because the annealing in a vacuum improves the orientation of the ZnS: Mn light emitting layer to the (111) plane, and the Mn light emission center is replaced with the position of Zn, thereby improving the crystallinity. As a result, the chromaticity coordinates x and y values of the thin film EL panel move in the direction of the second light emitting layer 36, and white light is emitted.
[0071]
Further, with the improvement of the crystallinity of the second light emitting layer 36, the electric field at which the light emission of the second light emitting layer 36 starts to be emitted can be reduced. Can also be realized.
[0072]
Also, looking at the emission characteristics of the thin-film EL panel in which the Mn concentration was increased in the region where the initial film thickness was up to 50 nm when the second light emitting layer 36 was formed, the second light emission after vacuum annealing was confirmed. Whitening of the emission color and lowering of the driving voltage accompanying the improvement of the characteristics of the layer 36 are similarly realized. Comparing the above with a thin-film EL panel in which the Mn concentration is uniformly added during the formation of the second light-emitting layer 36, an improvement in emission luminance of about 10% has been achieved (230 cd / m2). ² From 255 cd / m ² Improved).
[0073]
Further, Mn is thermally diffused from the second light emitting layer 36 to the non-added zinc sulfide layer by the annealing, and the region of the non-added zinc sulfide layer 35 can be used as a light emitting layer. At this time, the Mn concentration of the portion of the second light emitting layer 36 near the interface between the non-added zinc sulfide layer 35 and the second light emitting layer 36 is set to be higher than the other portions of the second light emitting layer 36. Therefore, the amount of thermal diffusion of Mn into the non-added zinc sulfide layer 35 increases, and the non-added zinc sulfide layer 35 reliably becomes a light-emitting layer to which Mn is added. Has the same effect as increasing the thickness.
[0074]
Accordingly, the region of the non-added zinc sulfide layer 35 can be used as a light emitting layer by the effect of the heat diffusion, and thus the light emission luminance in the thin film EL panel can be improved. At the time of this thermal diffusion, even if the non-added zinc sulfide layer 35 changes to the second light emitting layer 36, bumping foreign matters do not enter, so that the function of the etchant as a stopper layer does not decrease. Moreover, since the Mn concentration in the portion of the second light emitting layer 36 near the non-added light emitting layer 35 is high, even if Mn is thermally diffused from the portion of the second light emitting layer 36 to the non-added zinc sulfide layer 35, The Mn concentration in the portion of the second light emitting layer 36 can be maintained at a predetermined value, and the light emission luminance can be extremely high.
[0075]
A similar phenomenon occurs in the thin-film EL panel in which the Mn concentration of the second light emitting layer 36 is uniformly added. However, when the diffused Mn concentration is low, the non-added zinc sulfide layer 35 is added to the ZnS: Mn light emitting layer. The probability of change is low, and it is assumed that the effect of improving luminance is small. Further, in the thin-film EL panel in which the light emission luminance is improved by forming a high concentration region of Mn concentration on the non-added zinc sulfide layer 35, the blue-green light emission of the SrS: Ce first light emission layer 34 and the ZnS: The Mn second light-emitting layer 36 exhibited white light with a mixture of yellow and orange colors, and could maintain stable light-emitting characteristics even after accelerated aging for 1000 hours (50,000 hours in actual operation).
[0076]
As described above, there is chemical resistance between the first light emitting layer 34 using the alkaline earth metal sulfide as a base material and the second light emitting layer 36 using zinc sulfide as a base material. An additive-free zinc sulfide layer 35 is inserted. The bumping foreign matter generated when the second light emitting layer 36 is formed does not come into direct contact with the first light emitting layer 34 containing alkaline earth metal sulfide as a base material by the non-added zinc sulfide layer 35. . As described above, since the non-added zinc sulfide layer 35 functions as a stopper layer, an etchant or cleaning water is applied to the first light emitting layer 34 through the bumping foreign matter portion of the second light emitting layer 36 by a photo process of forming an electrode or the like. Even if an attempt is made to penetrate, it is possible to prevent intrusion into the first light emitting layer 34 and prevent the first light emitting layer 34 from being altered. Therefore, even if the alkaline earth metal sulfide having extremely low chemical resistance is used for the light emitting layer, the light emitting layer can be prevented from being deteriorated. In addition, since the non-added zinc sulfide layer 35 can prevent the first light-emitting layer 34 from being deteriorated, various kinds of light-emitting layer materials can be combined.
[0077]
According to the method of manufacturing the thin-film EL panel, annealing is performed before the one electrode is formed, so that the first light-emitting layer 34 having an alkaline earth metal sulfide as a base material, the zinc sulfide without addition, By improving the crystallinity of the layer 35 and the second light emitting layer 36 in advance, it is possible to reduce damage when an etchant or cleaning water enters through a foreign substance portion, a pinhole, or the like.
[0078]
(Fourth embodiment)
FIG. 4 is a sectional view of a color EL panel device according to a fourth embodiment of the present invention. This color EL panel device is manufactured by the following manufacturing steps.
[0079]
First, the lower electrode 4 is placed on a glass substrate 41 such as OA-2 (manufactured by NEC Corporation).
Form 2 The lower electrode 42 is formed by depositing a high melting point metal such as Ta, Mo, W or the like to a thickness of 100 nm to 400 nm by various thin film forming methods (sputtering method, electron beam evaporation method, spraying method, etc.), It is patterned into a stripe by an etching process.
[0080]
Next, a lower insulating layer 43 is formed on the lower electrode. This lower insulating layer 43 is made of SiO 2 by sputtering or the like. ₂ , SiN, Ta ₂ 0 ₅ Or SrTiO ₃ It is formed to a thickness of 200 nm to 500 nm by the above method.
[0081]
Next, a first light emitting layer 44 having a thickness of 800 nm to 1500 nm is formed on the lower insulating layer 43 by using, for example, an SrS: CeN pellet as an evaporation source by an electron beam evaporation method. The first light emitting layer 44 uses alkaline earth metal sulfide SrS as a base material and impurity CeN as a light emission center. During the deposition of the first light emitting layer 44, the temperature of the glass substrate 41 is maintained at 450 ° C. to 650 ° C. The SrS: CeN pellets are obtained by adding 0.05 to 0.3 wt% of CeN to SrS and firing.
[0082]
Next, the non-added zinc sulfide layer 45 having a thickness of 50 nm to 100 nm is formed on the first light emitting layer 44 by electron beam evaporation using the non-added ZnS pellet as an evaporation source. During the deposition of the non-added zinc sulfide layer 45, the temperature of the glass substrate 41 is maintained at 200 ° C to 300 ° C.
[0083]
Next, a second light emitting layer 46 made of ZnS: Mn having a thickness of 150 to 300 nm is formed on the non-added zinc sulfide layer 45 by using an electron beam evaporation method. In the second light emitting layer 46, zinc sulfide ZnS is a base material, and manganese Mn is a light emission center (impurity). This electron beam evaporation method is a two-source evaporation method in which ZnS pellets and MnS pellets are used as evaporation sources to control the Mn concentration in the film of the second light emitting layer 46, and the temperature of the glass substrate 41 at this time is controlled. Is maintained at 200 ° C to 300 ° C. The Mn concentration in the initial region (0 nm to 50 nm or 0 nm to 100 nm) is set to a high concentration (0.4 to 0.5 wt%), and the Mn concentration in the remaining region (50 nm to 300 nm) is set to the normal optimum concentration (0 to 50 nm). 0.2 to 0.25 wt%) to form the second light emitting layer 46.
[0084]
Next, an upper insulating layer 47 is formed on the second light emitting layer 46 by a process similar to that for the lower insulating layer 43.
[0085]
After the formation of the upper insulating layer 47, the crystallinity of the first light emitting layer 44, the zinc sulfide layer 45 with no addition, and the second light emitting layer 46 are improved, and the high concentration of Mn of the second light emitting layer 46 is improved. In order to thermally diffuse Mn from the region (0 nm to 50 nm or 0 nm to 100 nm) into the above-mentioned non-added zinc sulfide layer 45, heat treatment is performed at 600 to 650 ° C. in a vacuum and heat treatment is performed for 1 to 2 hours.
[0086]
Finally, a transparent electrode (ITO or ZnO: Al) having a thickness of 100 nm to 500 nm is formed on the upper insulating layer 47, and a stripe-shaped upper electrode 48 is formed by photolithography in a direction orthogonal to the lower electrode 12. I do.
[0087]
In the etching of the upper electrode 48 of the thin film EL panel having the above structure, a commercially available ITO etchant or HBr solution mixed with 50% sulfuric acid was used (volume ratio of 50% sulfuric acid to ITO etchant or HBr solution). 20-50%). Sulfuric acid contained in this etching solution precipitates invariant sulfur by reacting with the sulfide-based light-emitting layer (second light-emitting layer 46), thereby preventing the light-emitting layer from being damaged by the intrusion of the etchant. There is.
[0088]
The thin film EL panel emits light at the intersection of the lower electrode 42 and the upper electrode 48 by applying an AC voltage between the lower electrode 42 and the upper electrode 48. In the fourth embodiment, white light emission is obtained in which blue-green light emission of the first light emitting layer 44 (SrS: Ce) and yellow-orange light emission of the second light emitting layer 46 (ZnS: Mn) are mixed.
[0089]
Next, a black dye was contained in the photocurable resin having a thickness of 10 μm by a spin coating method at a position spaced 10 μm from the upper electrode 48 (electrode interval: 50 μm) for driving the thin film EL panel. After preparing the material, a black spacer 50 was formed in a stripe shape with a width of 30 μm by a photo process. By employing the black spacer 50, the contrast is improved, and the visibility is improved.
[0090]
Then, a red filter R (CR-7001; manufactured by Fuji Hunt), a green filter G (CG-7001; manufactured by Fuji Hunt), and a blue filter B (CB-7001; Fuji) are provided under a translucent substrate 55 such as glass. (Made by Hunt) are arranged on the black spacer 50 of the thin-film EL panel by forming a color filter 54 formed in stripes by photolithography. The light transmitting substrate 55 forming the color filter 54 has a frame-shaped recess 52 (width) filled with a moisture absorbing material 53 for capturing moisture that has entered from the outside and preventing moisture absorption and separation in the thin film EL panel. 3 to 10 mm and a depth of 0.3 to 1 mm).
[0091]
Thereafter, the glass substrate 41 on which the thin-film EL panel is formed and the translucent substrate 55 are bonded together using an epoxy resin 49 or the like in which a small amount of a gap material such as a glass rod is mixed.
[0092]
Next, the space between the glass substrate 41 and the translucent substrate 55 (the space 51 between the end of the thin film EL panel and the epoxy resin 49 for bonding the substrate), the upper electrode 48 and the color filter 54 Silicon oil mixed with silica gel as a moisture-absorbing material is injected into the space (space 56) to seal and seal, and an oil seal is performed to complete a color EL panel device. At this time, the width of the gap between the substrates to be bonded greatly affects the viewing angle dependency of the color EL panel device, and a wide viewing angle of 160 degrees vertically, horizontally, and horizontally is ensured by controlling the width between the electrodes to about 1/2 or less.
[0093]
Further, in a color EL panel device having a high definition specification, the width between electrodes is often set to 50 μm or less, and it is desirable to set the gap width to 30 μm or less except for a special large panel. As one of the major factors that determine the life of the color EL panel device, a dark spot is generated on the display unit due to an expansion phenomenon of a non-light emitting region due to the occurrence of moisture absorption separation. This is because the moisture that has penetrated through the substrate bonding portion described in the above-described panel manufacturing process reaches the thin-film EL panel and causes delamination of the thin film. Therefore, how to reduce and capture the invading moisture will affect the panel life. In the fourth embodiment, a structure in which the invading water is absorbed by the hygroscopic material 53 is adopted, and environmental reliability of 100,000 hours or more can be secured. The color EL panel device manufactured through the above steps separates the white EL light with each of the R, G, and B color filters to extract the R, G, and B light, thereby obtaining a multi-color based on the three primary colors. Color emission is possible. Then, even after accelerated aging equivalent to 30,000 hours of actual driving, the color filter 54 does not deteriorate due to the influence of dielectric breakdown or the like, and remains high for a long time without moisture absorption and peeling occurring due to intrusion of moisture. The display quality was maintained.
[0094]
As described above, there is chemical resistance between the first light emitting layer 44 using the alkaline earth metal sulfide as a base material and the second light emitting layer 46 using zinc sulfide as a base material. An additive-free zinc sulfide layer 45 is inserted. The bumping foreign matter generated when the second light emitting layer 46 is formed does not come into direct contact with the first light emitting layer 44 whose base material is an alkaline earth metal sulfide by the non-added zinc sulfide layer 45. . As described above, since the non-added zinc sulfide layer 45 functions as a stopper layer, an etchant or cleaning water is applied to the first light emitting layer 44 via the bumping foreign matter portion of the second light emitting layer 46 by a photo process for forming an electrode or the like. Even if an attempt is made to invade, the intrusion into the first light emitting layer 44 can be prevented, so that the first light emitting layer 44 can be prevented from being deteriorated. Therefore, even if the alkaline earth metal sulfide having extremely low chemical resistance is used for the light emitting layer, the light emitting layer can be prevented from being deteriorated. Further, since the first light emitting layer 44 can be prevented from being deteriorated by the non-added zinc sulfide layer 45, various kinds of light emitting layer materials can be combined.
[0095]
In addition, it can be seen that when the thickness of the non-added zinc sulfide layer 45 is set to 30 nm or more, it is possible to prevent the etchant from entering the first light emitting layer 44 and prevent the first light emitting layer 44 from being deteriorated.
[0096]
Furthermore, when the thickness of the above-mentioned zinc sulfide layer 45 with no addition is set to 50 nm or more, it is found that the etchant can be prevented from entering the first light emitting layer 44 and the first light emitting layer 44 can be more reliably prevented from being deteriorated. .
[0097]
Therefore, in order to reduce the etching damage of the first light emitting layer 44 containing alkaline earth metal sulfide as a base material, the thickness of the additive-free zinc sulfide layer 45 laminated on the first light emitting layer 44 should be 30 nm or more. It is understood that it is necessary to minimize the thickness, and it is more preferable to set the thickness to 50 nm or more.
[0098]
Further, since the driving voltage limit of the driver IC for actually driving the thin-film EL panel is about 250 V, considering the voltage obtained by adding the modulation voltage of 40 to 50 V to the driving voltage value in Table 1, the zinc sulfide layer having no additive is used. It is considered that the film thickness of 45 is 300 nm. Considering the driving voltage limit more strictly, the upper limit is 200 nm in thickness of the zinc sulfide layer 45 with no addition.
[0099]
Therefore, in the thin film EL panel, the thickness of the non-added zinc sulfide layer 45 needs to be set to 30 nm to 300 nm, and the thickness of the non-added zinc sulfide layer 45 needs to be further set to 50 nm to 200 nm. It is preferable to set.
[0100]
Further, Mn forming a light emission center is thermally diffused from the second light-emitting layer 46 to the non-added zinc sulfide layer 45, and the region of the non-added zinc sulfide layer 45 is used as a light-emitting layer by the heat diffusion effect. Since it can be used, the luminance can be improved.
[0101]
Further, Mn is thermally diffused from the second light emitting layer 46 to the non-added zinc sulfide layer by the annealing, and the region of the non-added zinc sulfide layer 45 can be used as a light emitting layer. At this time, the Mn concentration of the portion of the second light emitting layer 46 near the interface between the non-added zinc sulfide layer 45 and the second light emitting layer 46 is set to be higher than the other portions of the second light emitting layer 46. Therefore, the amount of thermal diffusion of Mn into the non-added zinc sulfide layer 45 is increased, and the non-added zinc sulfide layer 45 is surely a light emitting layer to which Mn is added. In addition, since the Mn concentration in the portion of the second light emitting layer 46 near the non-added light emitting layer 45 is high, even if Mn is thermally diffused from the portion of the second light emitting layer 46 to the non-added zinc sulfide layer 45, The Mn concentration in the portion of the second light emitting layer 46 can be maintained at a predetermined value, and the light emission luminance can be extremely high.
[0102]
Further, according to the method for manufacturing a thin film EL panel, annealing is performed before the one electrode is formed, so that the first light emitting layer 44 using an alkaline earth metal sulfide as a base material, the zinc sulfide without addition, By improving the crystallinity of the layer 45 and the second light emitting layer 46 in advance, it is possible to reduce damage when an etchant or cleaning water enters through a foreign substance portion, a pinhole, or the like.
[0103]
According to the color EL panel device, a combination of the thin film EL panel having excellent environmental resistance and a color filter can realize a color EL panel device having excellent long-term reliability.
[0104]
In the first to fourth embodiments, SrS and CaS are used as the alkaline earth metal sulfide as the base material of the first light emitting layers 14, 24, 34, and 44, but the base material of the first light emitting layer is used as the base material. The alkaline earth metal sulfide used is not limited to this.
[0105]
In the first to fourth embodiments, zinc sulfide in which Mn or Er is added is used for the second light emitting layers 16, 26, 36, and 46, but zinc sulfide which is a base material of the second light emitting layer is added. The impurity to be formed is not limited to this, and may be any impurity that forms the light emission center.
[0106]
【The invention's effect】
As is clear from the above, according to the thin-film EL panel of the first aspect, the first light-emitting layer whose base material is the alkaline earth metal sulfide having extremely low chemical resistance, and the first light-emitting layer whose base material is zinc sulfide. Between two light emitting layers , With chemical resistance You To No additive zinc sulfide layer Since the stopper layer is inserted, bumping foreign substances adhering to the second light emitting layer do not come into direct contact with the first light emitting layer, thereby preventing an etchant or cleaning water from entering the first light emitting layer. Thus, the first light emitting layer can be prevented from being deteriorated.
[0107]
Claims 2 According to the thin film EL panel of Unwritten Since the thickness of the added zinc sulfide layer is set to 30 nm to 300 nm, penetration of an etchant or the like into the first light emitting layer can be prevented, and the driving voltage can be suppressed within an allowable range.
[0108]
Claims 3 According to the thin film EL panel of Unwritten Since the thickness of the added zinc sulfide layer is set to 50 nm to 200 nm, intrusion of an etchant or the like into the first light emitting layer can be more reliably prevented, and the driving voltage can be reliably suppressed to an allowable range.
[0109]
Claims 4 According to the thin film EL panel of the above, from the second light emitting layer to which Mn is added, Unwritten Since Mn is thermally diffused into the added zinc sulfide layer, the region of the non-added zinc sulfide layer can be used as a light emitting layer, and therefore, the luminance can be improved.
[0110]
Claims 6 According to the method of manufacturing a thin-film EL panel described above, the Mn concentration of the portion of the second light-emitting layer near the interface between the undoped zinc sulfide layer and the second light-emitting layer is higher than that of the other portion of the second light-emitting layer. Also, since the first light emitting layer, the non-added zinc sulfide layer and the second light emitting layer are laminated and annealed in a state where the Mn concentration is high, the heat of Mn to the non-added zinc sulfide layer is increased. Since the amount of diffusion is increased and the undoped zinc sulfide layer becomes a light emitting layer to which Mn is surely added, the Mn concentration in the portion of the second light emitting layer near the light emitting layer without the additive is high. Even when Mn is thermally diffused from the light emitting layer portion to the zinc sulfide layer to which no Mn is added, the Mn concentration in the second light emitting layer portion is maintained at a predetermined value, and the light emission luminance does not decrease.
[0111]
Claims 7 According to the method of manufacturing a thin-film EL panel of the above, annealing is performed before the formation of the one electrode, so that the first light-emitting layer having an alkaline earth metal sulfide as a base material, the undoped zinc sulfide layer and the second By improving the crystallinity of the light emitting layer in advance, it is possible to reduce damage when an etchant or cleaning water enters through a foreign substance portion, a pinhole, or the like.
[0112]
Claims 8 The color EL panel device of the invention of claim 1 5 Since a structure in which any one of the above-described thin-film EL panel having excellent environmental resistance and a color filter are combined is used, a highly reliable color EL panel device can be realized for a long period of time.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a thin-film EL panel according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a configuration of a thin-film EL panel according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a configuration of a thin-film EL panel according to a third embodiment of the present invention.
FIG. 4 is a cross-sectional view of a color EL panel device according to a fourth embodiment of the present invention.
FIG. 5 is a cross-sectional view showing a configuration of a conventional thin-film EL panel.
[Explanation of symbols]
1,11,21,31,41,55 ... Transparent substrate,
2, 12, 22, 32, 42 ... lower electrode, 8, 18, 28, 38, 48 ... upper electrode
3, 13, 23, 33, 43 ... lower insulating layer, 7, 17, 27, 37, 47 ... upper insulating layer, 4, 6, 15, 25, 35, 45 ... additive-free zinc sulfide layer,
5, 14, 24, 34, 44 ... first light emitting layer, 16, 26, 36, 46 ... second light emitting layer
49 ... epoxy resin, 50 ... spacer, 51, 56 ... space,
52: Frame-shaped digging groove
53: moisture absorbing material, 54: color filter

Claims (8)

In a thin-film EL panel used for a filter-type color EL panel device, a plurality of light-emitting layers are sandwiched between insulating layers, electrodes are provided on the surfaces of these insulating layers,
The plurality of light-emitting layers are a first light-emitting layer to which impurities are added using alkaline earth metal sulfide as a base material and a second light-emitting layer to which impurities are added using zinc sulfide as a base material,
Inserting a stopper layer between the first light emitting layer and the second light emitting layer to prevent an etchant from entering the first light emitting layer ;
The thin-film EL panel according to claim 1, wherein the stopper layer is an additive-free zinc sulfide layer . 2. The thin film EL panel according to claim 1 , wherein the thickness of the zinc sulfide layer with no addition is in a range of 30 nm to 300 nm. 3. The thin-film EL panel according to claim 2 , wherein the thickness of the non-added zinc sulfide layer is in a range of 50 nm to 200 nm. 2. The thin-film EL panel according to claim 1 , wherein said first light-emitting layer is made of SrS as a base material, and said second light-emitting layer is made of zinc sulfide to which Mn is added. In a method of manufacturing a thin film EL panel used for a filter type color EL panel device,
Forming a lower electrode on the substrate;
Forming a lower insulating layer on the lower electrode;
Forming a first light emitting layer to which impurities are added using the alkaline earth metal sulfide as a base material on the lower insulating layer;
Forming a stopper layer on the first light emitting layer to prevent an etchant from entering the first light emitting layer;
Forming a second light-emitting layer to which impurities are added using zinc sulfide as a base material by an electron beam evaporation method on the stopper layer;
Forming an upper insulating layer on the second light emitting layer;
Forming a patterned upper electrode by etching on the upper insulating layer. 5. The method of manufacturing a thin-film EL panel according to claim 4 , wherein a first step of sequentially laminating the first light-emitting layer, the non-added zinc sulfide layer, and the second light-emitting layer; Annealing the non-added zinc sulfide layer and the second light-emitting layer, thereby diffusing Mn of the second light-emitting layer into a part of the non-added zinc sulfide layer,
In the first step, a state in which the Mn concentration of the portion of the second light emitting layer near the interface between the non-added zinc sulfide layer and the second light emitting layer is higher than the other portions of the second light emitting layer A method for manufacturing a thin-film EL panel, characterized in that: 7. The method for manufacturing a thin film EL panel according to claim 6 , wherein an electrode, an insulating layer, the first light emitting layer, the non-added zinc sulfide layer, the second light emitting layer, and an insulating layer are sequentially laminated and annealed. Thereafter, another electrode is formed, the method for manufacturing a thin film EL panel. A color EL panel device having a structure in which the thin-film EL panel according to any one of claims 1 to 4 is combined with a color filter.

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