JP4232010B2 - Microstructure formation method - Google Patents

Description

【０１２４】
表１に示す結果から、開口部直径の大きさが開口部のピッチの１／１０以上１／３以下の範囲において、本発明の目的が達成されることが明らかである。
【０１２５】
また、表１に示す○印で得られたマイクロレンズの直径は、隣接するレンズ同士が接する状態の大きさから、隣接するレンズのエッチング領域が重なるがエッチング用マスクの剥離が生じない状態までの大きさであり、表１に示した開口部ピッチの１．０〜１．４倍の大きさであった。この結果から、表１を用いることにより、作製するマイクロレンズの直径寸法から開口部のピッチと開口部の直径を決めることができる。例えば、レンズの直径が３０〜４０μｍのマイクロレンズアレイを作製するには、表１から、開口部のピッチを３０μｍにした場合、開口部の直径を３〜１０μｍにすればよいことがわかる。
【０１２６】
また、開口部の形状が円形の替わりに正方形である場合についても、数多くの実験を実施したので、その結果について説明する。
【０１２７】
表２は、正方形の一辺の長さである開口部辺長と開口部のピッチとを変えてエッチング後の状況をまとめたものである。なお、表２に示される各印の意味については上記表１と同様である。
【０１２８】
【表２】

【０１２９】
表２に示す結果から、開口部辺長が開口部のピッチの１／１０以上１／３以下の範囲において、本発明の目的が達成されることが明らかである。このように、本発明は開口部の形状には大きく依存しないことが判明した。そのため、上記エッチング用マスクの開口部３ａの形状は、本実施形態では円形としているが、方形、楕円形、その他の形状でもよい。
【０１３０】
次に、エッチャント濃度に対する依存性について検討するためにフッ酸水溶液の濃度を変えてエッチングを行ったので、その結果について説明する。
【０１３１】
表３は、開口部のピッチ３０μｍ、開口部直径３μｍのエッチング用マスクを設けた場合について、フッ酸水溶液の濃度を５％、１０％、２０％、３０％とした場合のエッチング時間をまとめたものである。なお、このエッチング時間は、エッチングの進行が不溶物５の影響により自動的に停止するまでの時間を意味する。
【０１３２】
【表３】

【０１３３】
表３に示す結果から、フッ酸濃度が高いほどエッチングの進行が停止するまでの時間が短くなっている。また、それぞれのエッチング条件により得られたレンズ形状について観察を行ったところ、どの条件でもほぼ同様の形状が得られていることが判明した。これは、本発明がエッチャント４の濃度には大きく依存しないことを示唆している。すなわち、エッチャント濃度が多少変化し、これによりエッチングが停止するまでの時間が変動しても、エッチングが不溶物５により自動的に停止するため、オーバーエッチングが発生することはない。また、予め所定のエッチング時間より長めの時間を設定しておくことで、エッチング不足を防止することも可能である。
【０１３４】
なお、基板１に含有される、エッチャント４に溶解しない物質である不純物の濃度に関しては、エッチャント濃度が同じでも、不純物濃度が高い場合にはエッチングの進行の停止が早くなり、不純物濃度が低い場合には不溶物の生成が不十分となるためエッチングの進行の停止が遅くなる傾向がある。そのため、形成されるレンズの直径は、基板１の不純物濃度による影響を受けることとなる。このことから、基板１に含有される酸化アルミニウム等の不純物の濃度は基板内および基板間で一定である方がよい。
【０１３５】
次に、エッチャント４の温度に対する依存性について検討するためにフッ酸水溶液の温度を変えてエッチングを行ったので、その結果について説明する。
【０１３６】
表４は、エッチャント中のフッ酸濃度を１０％に固定し、エッチャント温度を変えてエッチング時間を調べた結果をまとめたものである。なお、このエッチング時間は、上記表３と同様にエッチングの進行が停止するまでの時間を意味する。
【０１３７】
【表４】

【０１３８】
表４に示す結果から、エッチャントの温度が高いほどエッチングの進行が停止するまでの時間が短くなっている。また、それぞれのエッチング条件により得られたレンズ形状について観察を行ったところ、どの条件でも同様の形状が得られていることが判明した。これは、本発明がエッチャントの温度にも大きく依存せず、厳密な温度管理が不要であることを意味する。また、濃度を変えた場合と同様に、厳密な時間管理が不要で、エッチング不足およびオーバーエッチングを防止することも可能である。
【０１３９】
次に、エッチング用マスクについての検討結果を以下に説明する。
【０１４０】
エッチング用マスクの材質については、エッチャント４により変質が発生しにくいこと、および基板１との密着性が高いことが好ましい。密着性が低い場合には、基板１とエッチング用マスクとの界面からエッチングが進行し、エッチングムラの一因となるためである。本実施形態のようなクロム層などの金属膜２は、フッ酸系エッチング液に対して変質しにくく、基板１との密着性がよい。
【０１４１】
次に、エッチング用マスクの金属膜２に用いたクロム層の厚みについて検討した結果を以下に説明する。
【０１４２】
表５はクロム層の厚みを１０ｎｍから５００ｎｍの間で変化させた場合のエッチング結果をまとめたものである。
【０１４３】
【表５】

【０１４４】
表５に示すように、クロム層の厚みが１０ｎｍ以下の場合と５００ｎｍ以上の場合にクロム層がマスクとして使用できない状態になり、その理由は以下の通りである。
【０１４５】
クロム層の厚みが１０ｎｍ以下の場合にはクロム層にピンホールが発生し、エッチング用マスクとしての機能が十分に発揮できないため、エッチング用マスクの剥離が発生して、良好なエッチング状態を得ることができなかった。また、クロム層の厚みが５００ｎｍ以上の場合には多数のクラックが発生するとともに、エッチングの進行に伴ってクロム層の応力に起因すると考えられる剥離が発生して、良好なエッチング状態を得ることができなかった。このため、本発明におけるクロム層の厚みは２０ｎｍから３００ｎｍの範囲に設定されることが好ましい。また、クロムのかわりにシリコン、チタン、銀、白金、金などを使用することができるが、クロムの場合と同様な現象が発生するため、上記の厚みの範囲で使用することが好ましい。
【０１４６】
次に、エッチング用マスクのレジスト３の厚みについて検討した結果を以下に説明する。
【０１４７】
表６はレジスト３の厚みを１００ｎｍから６０００ｎｍの間で変化させた場合のエッチング結果をまとめたものである。
【０１４８】
【表６】

【０１４９】
表６に示すように、レジスト３の厚みが１００ｎｍ以下の場合と６０００ｎｍ以上の場合にレジスト３がマスクとして使用できない状態になり、その理由は以下の通りである。
【０１５０】
レジスト３の厚みが１００ｎｍ以下の場合にはエッチングの進行とともにエッチング用マスクの剥離が発生して、良好なエッチング状態を得ることができなかった。また、レジスト３の厚みが６０００ｎｍ以上の場合にも、エッチングの進行とともにエッチング用マスクの剥離が発生して、良好なエッチング状態を得ることができなかった。このため、本発明におけるレジスト３の厚みは２００ｎｍから４０００ｎｍの範囲に設定されることが好ましい。
【０１５１】
なお、本実施形態は、マイクロレンズアレイのみならず、単体のマイクロレンズの形成にも同様に適用することが可能である。
【０１５２】
本実施形態では、上述したように、不溶物５が生成されることで基板１のエッチングが自動的に停止する効果により、エッチングが停止した後に基板１をエッチャント４に浸していてもエッチングが進行しない。そのため、エッチング停止後に基板１をエッチャント４から取り出す時間のマージンを大きく確保できる。
【０１５３】
また、複数枚の基板１を一度に加工する際にも、上記不溶物５の生成が基板間で均一なため、基板間で均一な加工が可能になる。また、一枚の基板１を複数回のエッチング処理で加工する場合にも、上記不溶物５の生成がエッチング処理間で均一なため、エッチング処理間で均一な加工が可能となる。そのため、基板１が大型化しエッチャント濃度やエッチング時間に面内分布が発生しても、基板面内のみならず基板間で均一なレンズパターンを作製することができ、基板面内および基板間における凹部形状の均一性により歩留りが向上し、ウェットエッチングにより低コスト化が可能となる。
【０１５４】
また、発生した不溶物５がエッチング用マスクの支えの役割を果たすため、金属膜２およびレジスト３から構成されるエッチング用マスクの剥離を防止することができ、より均一性の高い加工が可能になる。さらに、無アルカリガラス、低アルカリガラス、ホウ珪酸ガラス、鉛ガラスなどの液晶表示用ガラスは石英ガラス基板やシリコンウェハ基板と比較して安価であり、本実施形態では、これらの液晶表示素子用ガラスを使用することができるため、低コスト化も実現可能である。
【０１５５】
なお、本実施形態によるマイクロレンズアレイ基板１２を液晶表示素子に応用する場合について説明する。
【０１５６】
図２は液晶表示素子の外観を模式的に示す斜視図である。
【０１５７】
図に示すように、液晶表示素子は、マイクロレンズアレイ基板１２上に設けられた調整用ガラス板５１と公知の方法により作製されたＴＦＴ基板５０との間に液晶層５２が挟まれる構成である。
【０１５８】
上記構成の液晶表示素子では、図の下側から照射された光がマイクロレンズアレイ基板１２に設けられたマイクロレンズによりＴＦＴ基板５０の透過部で集光するように構成されているため、光を透過するように液晶分子が配列した部分の輝度が高くなる。また、本実施形態のマイクロレンズアレイ基板１２を用いることにより、表示面内の輝度が均一になる。
【０１５９】
上記液晶表示素子の作製方法について説明する。
【０１６０】
図３乃至図５は液晶表示素子の作製方法を製造工程順に示した断面図である。
【０１６１】
図３（Ａ）に示すように、無アルカリガラスの基板２０１上に金属膜２０２およびレジスト２０３を順に形成し、公知のリソグラフィ工程およびエッチング工程によりレジスト２０３と金属膜２０２に開口部２０３ａを形成する。開口部２０３ａを形成する際、以下に説明する露光位置調整マーカ２０３ｂを形成する。なお、図１では、露光位置調整マーカ２０３ｂを図に示すことを省略した。
【０１６２】
露光位置調整マーカ２０３ｂは基板２０１上の所定の場所に必要な数だけ設けられている。露光位置調整マーカ２０３ｂは、ステッパ露光機による、上記開口部２０３ａを形成するための第１の露光とそれ以降に行う露光の際、ステッパ露光機用マスクであるレチクルやＴＦＴ基板等との相対的な位置決めのために用いられる位置合わせ手段であり、一般的にその精度は１μｍ以下である。なお、工程数は増えるが露光位置調整マーカ２０３ｂを形成した後に、開口部２０３ａを形成してもよい。
【０１６３】
続いて、図３（Ｂ）に示すように、基板２０１をエッチャントに浸す前に、露光位置調整マーカ２０３ｂをエッチャントから保護するための保護材２５３を形成する。この保護材２５３はエッチャントに対する耐性を有するものであればよく、保護材２５３として、特に保護テープやエポキシ系樹脂材料等を好適に用いることが可能である。
【０１６４】
そして、図３（Ｃ）に示すように、基板２０１をエッチャントに浸して、基板２０１のエッチングを行う。このとき、保護材２５３が露光位置調整マーカ２０３ｂの形状変化や剥離を防止する。また、レンズとなる凹部の周囲に柱状パターン２０１ａを有するため、レジスト２０３と金属膜２０２の剥離を防止する。
【０１６５】
その後、図３（Ｄ）に示すように、保護材２５３を剥離し、レジスト２０３と、露光位置調整マーカ２０３ｂ以外の金属膜２０２を剥離する。ここでは、保護材２５３を剥離したが、この後のステッパ露光機によるステッパ露光の際、問題とならなければ特に剥離する必要はない。
【０１６６】
続いて、図３（Ｅ）に示すように、マイクロレンズアレイ基板２１２の凹部形成面に高屈折率接着剤２５４を塗布して透明な調整用ガラス板２５１を貼合する。このとき、マイクロレンズアレイのレンズの焦点距離を調整して、レンズとしての効果が最大となるように調整用ガラス板２５１の厚さを調整する。マイクロレンズアレイ基板２１２に調整用ガラス板２５１を貼り合わせた後に調整用ガラス２５１を薄くして厚さ調整してもよいが、予め厚さ調整した調整用ガラス板２５１をマイクロレンズアレイ基板２１２に貼合してもよい。貼合後に薄くする場合には、エッチング法や機械研磨法を好適に用いることが可能である。このように透明基板として調整用ガラス板２５１を凹部形成面側に貼合することで、凹部に埋め込まれた高屈折率接着剤２５４の形状を維持し、凹部で屈折した光が調整用ラス板２５１を透過可能となる。
【０１６７】
その後、調整用ガラス板２５１上にクロムやアルミニウム等の薄膜を成膜し、その上にレジストを塗布する。そして、重ね合わせ位置調整マーカ２５５および画素遮光部２５６のパターンを形成するためのレチクルに備えたマーカと、露光位置調整マーカ２０３ｂを使用して、レチクルとマイクロレンズアレイ基板２１２を位置決めして、ステッパ露光および現像を行う。続いて、エッチングによりレジストマスクの形状に合わせたパターンを形成するパターニングにより、重ね合わせ位置調整マーカ２５５と画素遮光部２５６を形成する（図３（Ｆ））。
【０１６８】
このように、ステッパ露光時のレチクルとマイクロレンズアレイ基板２１２の位置決めのために露光位置調整マーカ２０３ｂを使用している。そのため、重ね合わせ位置調整マーカ２５５と画素遮光部２５６をより正確に所望の位置に配置できる。この重ね合わせ位置調整マーカ２５５は、液晶表示素子を作製する際に使用するＴＦＴ基板と高精度に重ね合わせるために用いられる。ＴＦＴ基板との重ね合わせを高精度に行い得るため、画素遮光部２５６等の重ね合わせマージンをより小さくでき、開口率がより高くなり、より明るい表示が可能な液晶表示素子を作製可能となる。なお、画素遮光部２５６はＴＦＴ等に光が当たるのを防止するための遮光手段である。
【０１６９】
その後、公知の方法により、調整用ガラス板２５１上に、図に示さない透明電極および配向膜等を形成する。
【０１７０】
なお、上記高屈折率接着剤を用いて貼合する代わりに、形成された凹部に高屈折率材料を埋め込み、調整用ガラス板２５１とほぼ同一の屈折率の接着剤を用いてマイクロレンズアレイ基板２１２と調整用ガラス板２５１を接着してもよい。また、上記高屈折率接着剤および高屈折率材料の屈折率を調整することで、マイクロレンズアレイのレンズの焦点距離を調整することが可能である。
【０１７１】
次に、ＴＦＴ基板とマイクロレンズアレイ基板を重ね合わせる方法について説明する。重ね合わせ方法は大きく分けて二つある。一つめの方法は、ＴＦＴ基板とマイクロレンズアレイ基板を重ね合わせた後に個片に切断する方法であり、二つめの方法は、ＴＦＴ基板とマイクロレンズアレイ基板を個片に切断してから重ね合わせる方法である。
【０１７２】
はじめに、一つめの重ね合わせ方法について説明する。
【０１７３】
図４は一つめの重ね合わせ方法を示す断面模式図である。
【０１７４】
図３（Ｆ）に示したマイクロレンズアレイ基板２１２を用意する（図４（Ａ））。続いて、図４（Ｂ）に示すように、公知の方法により作製されたＴＦＴ基板２５０とマイクロレンズアレイ基板２１２を、重ね合わせ位置調整マーカ２５５とＴＦＴ基板側重ね合わせ位置調整マーカ２５７を使用して位置を合わせ、シール剤２５８で貼り合わせる。このとき、ＴＦＴ基板２５０とマイクロレンズアレイ基板２１２には、液晶を入れるための隙間を設けている。なお、露光位置調整マーカ２０３ｂを形成するときに、重ね合わせ位置調整マーカをマイクロレンズアレイ基板２１２の表面に形成し、この重ね合わせ位置調整マーカをＴＦＴ基板２５０との重ね合わせ時に使用してもよい。
【０１７５】
続いて、図４（Ｃ）に示すように、切断箇所に高圧の水をかける切断方法で、貼り合わせたＴＦＴ基板２５０とマイクロレンズアレイ基板２１２を個片に分離し、貼り合わせた２枚の板の間に液晶を封入して液晶層２５２を形成して液晶表示素子２６０を得る。この切断方法によれば、マイクロレンズアレイ基板２１２と調整用ガラス板２５１が高屈折率接着剤２５４で貼合されているような構造でも、効率よく切断できる。なお、液晶層２５２を、ＴＦＴ基板２５０とマイクロレンズ基板２１２を貼り合わせる際に封入してもよい。
【０１７６】
次に、二つめの重ね合わせ方法について説明する。
【０１７７】
図５は二つめの重ね合わせ方法を示す断面模式図である。
【０１７８】
図５（Ａ）に示すように、マイクロレンズアレイ基板２１２を個片に切断する。個片にしたマイクロレンズアレイ基板２１２ａにも、重ね合わせ位置調整マーカ２５５が形成されている。続いて、図５（Ｂ）に示すように、個片にしたＴＦＴ基板２５０ａと個片にしたマイクロレンズアレイ基板２１２ａを、重ね合わせ位置調整マーカ２５５とＴＦＴ基板側重ね合わせ位置調整マーカ２５７を使用して位置を合わせ、シール剤２５８で貼り合わせる。貼り合わせた２枚の板の間に液晶を封入して液晶層２５２を形成し、液晶表示素子２６０を得る。
【０１７９】
なお、図４および図５では、マイクロレンズアレイ基板２１２の凹部形成面側に調整用ガラス基板２５１を貼り合わせ、調整用ガラス基板２５１とＴＦＴ基板２５０の間に液晶層２５２を形成したが、以下に説明するように、マイクロレンズアレイ基板２１２とＴＦＴ基板２５０の間に液晶層２５２を形成するようにしてもよい。
【０１８０】
図６は液晶表示素子の別の構成例を示す断面図である。
【０１８１】
図５に示した個片にしたマイクロレンズアレイ基板２１２ａの上下方向を逆にし、図６に示すように、個片にしたマイクロレンズアレイ基板２１２ａのレンズが図の上向きで凸形状になるようにしている。図６に示す構造を形成する場合には、レンズの効果が最大となるように個片にしたマイクロレンズアレイ基板２１２ａの厚さを調整している。マイクロレンズアレイ基板２１２の凹部形成面に調整用ガラス２５１を貼り合わせた後にマイクロレンズアレイ基板２１２の厚さを調整してもよいが、予めマイクロレンズアレイ基板２１２の厚さを調整してから調整用ガラス板２５１を貼合してもよい。貼合後に薄くする場合には、エッチング法や機械研磨法を好適に用いることが可能である。
【０１８２】
液晶表示素子のＴＦＴ基板とマイクロレンズアレイ基板は、単位長さあたりの熱膨張係数である線熱膨張係数が比較的近いことが好ましい。これら２枚の基板に線熱膨張係数が大きく異なるものを使用すると、ヒートサイクルでの基板剥離等による信頼性低下と、熱膨張による位置目合わせずれが問題になる。ＴＦＴ基板には、無アルカリガラスまたは石英基板が多く使用される。このとき、ＴＦＴ基板の基板の種類に応じて、マイクロレンズアレイ基板に無アルカリガラスやβ―石英型透明結晶化ガラス等を使用することで、ＴＦＴ基板とマイクロレンズアレイ基板の線熱膨張係数が等しくなり、上記問題の発生が抑制され、信頼性がより向上する。
【０１８３】
次に、作製された液晶表示素子を液晶プロジェクタの液晶ライトバルブとして応用する場合について説明する。
【０１８４】
図７は液晶プロジェクタの一構成例を示す模式図である。
【０１８５】
図に示すように、液晶プロジェクタは、光源１３０と、光源１３０からの光の偏光方向を揃えるとともに光強度を均一にする偏光変換インテグレータ１３２と、光源１３０からの白色光をダイクロイックミラー１３３、１３４により赤色、緑色および青色の３色の光束に分離する色分離光学系と、分離された光束の進行方向を変えるための全反射ミラー１３５〜１３７と、上記３色の光束が色別に照射される３枚の液晶表示素子１３８〜１４０と、これら３枚の液晶表示素子１３８〜１４０によって表示される画像を合成するためのクロスダイクロイックプリズム１４１からなる色合成光学系と、合成された表示画像をスクリーン上に拡大投射するための投射レンズ１４２とを備える構成である。
【０１８６】
液晶表示素子１３８〜１４０は、薄膜トランジスタ（ＴＦＴ）を画素毎に配列して液晶を駆動させるアクティブマトリクス型である。また、各液晶表示素子１３８〜１４０のクロスダイクロイックプリズム１４１側の面に、偏光方向が偏光変換インテグレータ１３２の偏光方向と直交する偏光板（不図示）が設けられている。
【０１８７】
次に、上記構成の液晶プロジェクタの動作について説明する。
【０１８８】
液晶プロジェクタは、図に示すように、光源１３０から出射された光をリフレクタ１３１で集光した後、その光束からダイクロイックミラー１３３で赤色の光束を分離し、ダイクロイックミラー１３４で緑色の光束を分離して、赤色、緑色および青色の３色の光束に分離する。赤色の光束は、全反射ミラー１３５で反射した後、赤色用液晶表示素子１３８を照明する。また、緑色の光束は緑色用液晶表示素子１３９を照明し、青色の光束は全反射ミラー１３６、１３７で順次反射した後、青色用液晶表示素子１４０を照明する。赤色、緑色、および青色の液晶表示素子１３８〜１４０に表示される各画像は、クロスダイクロイックプリズム１４１によって合成された後、投射レンズ１４２によりスクリーン（不図示）に拡大投影される。
【０１８９】
上記構成による液晶プロジェクタは、マイクロレンズが入射される光を画素の開口部に集光するため、輝度が向上してスクリーン上の投影像がより明るくなり、本発明のマイクロレンズアレイ基板１２を用いることにより、投影像の全体の明るさが均一になる。
【０１９０】
次に、上記液晶表示素子を液晶表示装置に応用する場合について説明する。
【０１９１】
図８は半透過型の液晶表示装置の外観を模式的に示す斜視図である。
【０１９２】
図に示すように、液晶表示装置は、上記液晶表示素子１５１と、偏光板１５２、１５３と、光源となるバックライトユニット１５４と、画素毎に設けられたＴＦＴに信号を送るための信号供給回路１５５と、バックライトユニット１５４および信号供給回路１５５に電源を供給する電源供給部１５６とを備える構成である。
【０１９３】
バックライトユニット１５４に赤色、緑色および青色からなる３原色のランプを設けて、この３原色ランプの点灯を高速で切り換える制御を行うことにより液晶表示装置の画面をカラー表示にできるが、バックライトユニット１５４に３原色ランプを設ける代わりに液晶表示素子１５１にカラーフィルターを設けてもよい。
【０１９４】
上記構成による液晶表示装置は、マイクロレンズアレイがバックライトの光利用率を高めるため表示がより明るくなり、本発明のマイクロレンズアレイ基板１２を用いることにより、表示画面内における輝度が均一になる。
【０１９５】
本実施形態による液晶表示素子を、例えば、特開２０００−２９８２６７号公報に示される半透過型の液晶表示装置に用いることができる。
【０１９６】
なお、本実施形態により作製された液晶表示素子を、上記半透過型の液晶表示装置に限らず、半透過型より遮光率の大きい微透過型、および半透過型より遮光率の小さい微反射型の液晶表示装置にも適用できる。
【０１９７】
（第２の実施形態）
第２の実施形態では、上記第１の実施形態により作製されたマイクロレンズアレイ基板１２を、２Ｐ成型法によるマイクロレンズアレイ作製のための母型に用いたものである。
【０１９８】
図９は本発明の第２実施形態を製造工程順に示した断面図である。
【０１９９】
まず、図９（Ａ）に示すように、母型６の凹部形成面に離型剤７と、樹脂８として紫外線硬化樹脂とを順に塗布した後、樹脂８を塗布した面を下側に向ける。
【０２００】
次に、基板３０として無アルカリガラスを用いて基板３０の面と樹脂８の面とを合わせて、母型６を基板３０側に押し付ける（図９（Ｂ））。樹脂８に紫外線を照射して硬化させた後、母型６を剥離することで、凸型に成型された樹脂８を基板３０上に形成し、樹脂８と基板３０とからなるマイクロレンズアレイ３２が得られる（図９（Ｃ））。
【０２０１】
なお、図９（Ｃ）に示した工程の後、樹脂８の上から全面に異方性エッチングを行い、樹脂８の凸型形状を基板３０に転写してもよい。
【０２０２】
また、上記樹脂８は、光照射により硬化する光硬化樹脂、加熱により硬化する熱硬化樹脂、または２液性接着剤であっても好適である。上記母型６の材料としては、基板３０と同種のものか、基板３０と熱膨張係数の近いものを用いるとよい。
【０２０３】
本実施形態では、上記第１の実施形態のマイクロレンズアレイ基板１２には大面積に均一な凹部形状が形成されているため、マイクロレンズアレイ基板１２を母型６に用いることで、大型の母型を高い歩留まりで安価に作製することが可能となる。
【０２０４】
また、母型６と基板３０に同種の材料、または熱膨張係数の近い材料を用いることにより、母型６の材料として金属や石英ガラス基板など、基板３０と異なる材料を用いる場合と比較して、熱膨張係数の違いに起因する誤差を小さくでき、厳密な温度管理が不要となる。また、熱硬化樹脂を用いた際の、加熱工程で生じる誤差を小さくすることができる。
【０２０５】
さらに、母型６および基板３０の材料として、安価な無アルカリガラスなどを用いることができるため、低コスト化が可能となる。また、大型の母型６を使用してマイクロレンズアレイ３２を成型できるため、小型の母型を用いて多数回、高精度で型押しする必要はなく、コスト面で有利となる。
【０２０６】
なお、本実施形態により作製されたマイクロレンズアレイ３２を液晶プロジェクタのライトバルブ用マイクロレンズアレイとして使用する場合には、次のような工程を追加する。
【０２０７】
まず、マイクロレンズアレイ３２の凸型成型面に樹脂８または基板３０に比べて低屈折率な接着剤を塗布してガラスを貼合する。次に、マイクロレンズアレイ３２の凸部に形成されたレンズの焦点が公知の方法で作製されたＴＦＴ基板の透過部に合うように、ガラスの厚みを調整した後、上記ＴＦＴ基板をマイクロレンズアレイ１２に貼り合わせて、ライトバルブ用マイクロレンズアレイを得る。
【０２０８】
この後、ライトバルブ用マイクロレンズアレイに配線となる透明電極や位置合わせのためのマーカなどの形成を行い、公知のパネル作製工程を実施することで、液晶プロジェクタ用のマイクロレンズアレイ付ライトバルブを得る。
【０２０９】
また、本実施形態により作製されたマイクロレンズアレイ３２を、マイクロレンズアレイ付液晶表示素子に応用するためには、次のような工程を実施すればよい。なお、マイクロレンズアレイ付液晶表示素子の応用例としては、半透過型、微透過型、または微反射型の液晶表示素子である。
【０２１０】
まず、適当な厚みの基板を用いて公知の方法により作製した液晶表示素子の光入射側基板の表面に樹脂８を塗布して、この樹脂８に上記母型６を用いて型押しを行った後、樹脂８を硬化させてマイクロレンズアレイ３２を得る。次に、マイクロレンズアレイ３２のレンズを透過するバックライト光がＴＦＴ基板の画素電極の透過部に集光するように位置合わせを行って、光入射側基板をＴＦＴ基板に組み付けることで、マイクロレンズアレイ付液晶表示素子を得る。これにより、レンズパターンの均一なマイクロレンズアレイ付液晶表示素子をより低コストで作製できる。
【０２１１】
（第３の実施形態）
第３の実施形態は、本発明を等方性エッチング法による光導波路の作製に適用する形態である。
【０２１２】
図１０は本発明の第３の実施形態を製造工程順に示した断面図である。
【０２１３】
図１０（Ａ）に示すように、基板１として、第１の実施形態と同様に、酸化アルミニウム等を均一に含有する無アルカリガラスを用いて、この基板１上に金属膜２およびレジスト３からなるエッチング用マスクを形成する。
【０２１４】
なお、光導波路のパターンに倣った四角形の開口部３ｂをエッチング用マスクに形成するが、開口部３ｂの対向する二辺の幅については、第１の実施形態で示した表１のような、上記開口部３ｂの幅と形成される光導波路の幅との関係を示す表を予め作成し、作成した表に基づいて形成される光導波路の幅から決定する。
【０２１５】
次に、エッチャント４としてフッ酸系エッチング液を用いて基板１のエッチングを行う。図１０（Ｂ）はエッチングの初期段階の状態を示した断面図である。
【０２１６】
エッチングが始まると、上記開口部３ｂから基板１の等方性エッチングが進行し、微小な溝部が形成される。この微小な溝部中の基板表面に、エッチングにより生じた、エッチャントに対する不溶物５であるフッ化アルミニウム等が蓄積し、基板１のエッチングの進行を阻害し、最終的にはエッチングが停止して光導波路パターンが形成される（図１０（Ｃ））。
【０２１７】
金属膜２およびレジスト３とともに不溶物５を除去した後、基板１に比べて屈折率の高い高屈折率材料を、形成された溝部に埋め込み、光導波路１３を形成する（図１０（Ｄ））。
【０２１８】
本実施形態では、基板１にエッチャント４に対する不溶物５を生成する物質として酸化アルミニウム等が含まれ、エッチングによりエッチャント４に対する不溶物５が生成されるため、ある程度エッチングが進行した状態でエッチングが自動的に停止し、エッチングストッパ層などを設けることなく、大面積の基板でも均一な光導波路のパターンを安価に作製することができる。また、各エッチング処理におけるエッチング量のばらつきがなく、エッチング処理間における凹部形状が均一な光導波路用パターンを形成できる。
【０２１９】
また、第１の実施形態で述べたように、基板１がオキシハライドガラスであれば、フッ酸系エッチング液に溶解しない物質としてフッ化カルシウム等が含有されるため、フッ化カルシウム等が上記不溶物５と同様な作用および効果を生じさせる。
【０２２０】
なお、金属膜２およびレジスト３とともに不溶物５を除去した後、作製された光導波路状の窪みパターンを母型にして、２Ｐ成型法を用いて別の基板上に高屈折率材料を成型した光導波路を形成することにより、ストリップ導波路やリブ導波路を得ることも可能である。この場合にも、大型の母型を高い歩留まりで安価に作製することが可能であること、熱膨張係数の違いに起因する誤差を小さくでき厳密な温度管理が不要となること、熱硬化樹脂を用いた際の加熱工程における誤差を小さくできること、母型の材料として安価な無アルカリガラスなどを用いることができるため低コスト化が可能であること、などの効果を得ることができる。
【０２２１】
（第４の実施形態）
第４の実施形態は、本発明を等方性エッチング法による埋め込み配線の作製に適用する形態である。
【０２２２】
図１１は本発明の第４の実施形態を製造工程順に示した断面図である。
【０２２３】
図１１（Ａ）に示すように、基板１として、第１の実施形態と同様に、酸化アルミニウム等を均一に含有する無アルカリガラスを用いて、この基板１上に金属膜２およびレジスト３からなるエッチング用マスクを形成する。
【０２２４】
なお、埋め込み配線のパターンに倣った四角形の開口部３ｃをエッチング用マスクに形成するが、開口部３ｃの対向する二辺の幅については、第１の実施形態で示した表１のような、上記開口部３ｃの幅と形成される埋め込み配線の幅との関係を示す表を予め作成し、作成した表に基づいて形成される埋め込み配線の幅から決定する。
【０２２５】
次に、エッチャント４としてフッ酸系エッチング液を用いて基板１のエッチングを行う。図１１（Ｂ）はエッチングの初期段階の状態を示した断面図である。
【０２２６】
エッチングが始まると、上記開口部３ｃより基板１の等方性エッチングが進行し、微小な溝部が形成される。この微小な溝部中の基板表面に、エッチングにより生じた、エッチャントに対する不溶物５であるフッ化アルミニウム等が蓄積し、基板１のエッチングの進行を阻害し、最終的にはエッチングが停止して配線パターンが形成される（図１１（Ｃ））。
【０２２７】
金属膜２およびレジスト３とともに不溶物５を除去した後、スパッタ法などの公知の方法を用いて、配線用金属層９を成膜する（図１１（Ｄ））。次に、化学的または機械的な研磨法を用いて、形成された溝部中以外の配線用金属層９を除去して、埋め込み配線９ａを形成する（図１１（Ｅ））。
【０２２８】
本実施形態では、基板１にエッチャント４に対する不溶物５を生成する物質として酸化アルミニウム等が含まれ、エッチングによりエッチャント４に対する不溶物５が生成されるため、ある程度エッチングが進行した状態でエッチングが自動的に停止し、大面積の基板でも均一な埋め込み配線用のパターンを安価に作製することができる。また、各エッチング処理におけるエッチング量のばらつきがなく、エッチング処理間における凹部形状が均一な埋め込み配線用パターンを形成できる。
【０２２９】
また、第１の実施形態で述べたように、基板１がオキシハライドガラスであれば、フッ酸系エッチング液に溶解しない物質としてフッ化カルシウム等が含有されるため、フッ化カルシウム等が上記不溶物５と同様な作用および効果を生じさせる。
【０２３０】
（第５の実施形態）
第５の実施形態は、本発明を等方性エッチング法による回折格子の作製に適用する形態である。
【０２３１】
図１２は本発明の第５の実施形態を製造工程順に示した断面図である。
【０２３２】
図１２（Ａ）に示すように、酸化アルミニウム等を均一に含有する無アルカリガラスの基板１上にスピンコートなどの公知の手法を用いて、レジスト３を塗布し、乾燥させる。なお、レジスト３としては、次工程の露光で使用する光の波長に対応し、かつ回折格子を形成できるだけの解像度を有するものを使用する。一例として、エキシマレーザ用フォトレジストを好適に使用することができる。
【０２３３】
この後、エキシマレーザ光などを使用してレジスト３に干渉露光を行い、レジストの現像工程を経て、微細な開口部３ｄからなる回折格子パターンを有するエッチング用マスクを形成する（図１２（Ｂ））。
【０２３４】
なお、回折格子のパターンに倣った四角形の開口部３ｄをエッチング用マスクに形成するが、開口部３ｄの対向する二辺の幅および開口部３ｄの間隔については、第１の実施形態で示した表１のような、上記開口部３ｄの幅および間隔と形成される回折格子の凹部の幅との関係を示す表を予め作成し、作成した表に基づいて形成される回折格子の凹部の幅から決定する。
【０２３５】
次に、エッチャント４としてフッ酸系エッチング液を用いて基板１のエッチングを行う。図１２（Ｃ）はエッチングの初期段階の状態を示した断面図である。
【０２３６】
エッチングが始まると、開口部３ｄ部分より基板１の等方性エッチングが進行し、微小な溝部が形成される。この微小な溝部中の基板１の表面に、エッチングにより生じた、エッチャント４に対する不溶物５であるフッ化アルミニウム等が蓄積し、基板１のエッチングの進行を阻害し、最終的にはエッチングが停止する。
【０２３７】
この後、レジスト３の剥離を行って不溶物５を洗い流すと、図１２（Ｄ）に示すように、複数の溝部が設けられた回折格子３４が形成される。
【０２３８】
本実施形態では、基板１にエッチャント４に対する不溶物５を生成する物質として酸化アルミニウム等が含まれ、エッチングによりエッチャント４に対する不溶物５が生成されるため、ある程度エッチングが進行した状態でエッチングが自動的に停止し、大面積の基板でも均一な回折格子のパターンを安価に作製することができる。また、各エッチング処理におけるエッチング量のばらつきがなく、エッチング処理間におけるパターン形状が均一な回折格子を形成できる。
【０２３９】
なお、基板１は、第１の実施形態と同様に、上記無アルカリガラスの他に、低アルカリガラス、ホウ珪酸ガラス、鉛ガラスでもよい。基板１がオキシハライドガラスであれば、フッ酸系エッチング液に溶解しない物質としてフッ化カルシウム等が含有されるため、フッ化カルシウム等が上記不溶物５と同様な作用および効果を生じさせる。
【０２４０】
また、このようにして作製された回折格子３４は、大面積・安価な光学素子として使用することもできるが、例えば、有機エレクトロルミネッセンス素子の基板として使用することで、光取り出し効率を向上することもできる。この場合には、安価な無アルカリガラス基板を使用して、安価な手法で大面積の回折格子３４を作製できる利点を最大限に活用することができる。
【０２４１】
（第６の実施形態）
第６の実施形態は、本発明を等方性エッチング法による液晶配向膜の作製に適用する形態である。
【０２４２】
図１３は本発明の第６の実施形態を製造工程順に示した断面図である。
【０２４３】
図１３（Ａ）に示すように、基板１上に透明電極１０を形成し、透明電極１０の上に液晶分子の配列方向を決めるための配向膜１１を形成する。なお、この配向膜１１は、酸化アルミニウム等を均一に含有させた無機材料の膜である。
【０２４４】
次に、図１３（Ｂ）に示すように、第５の実施形態と同様な方法を用いてエッチング用マスクを形成するが、四角形の開口部３ｅの長手方向を注入する液晶分子の配列方向にほぼ一致させておく。エッチング用マスクの材質としては、レジスト３などを好適に用いることができる。
【０２４５】
なお、形成される液晶配向膜のパターンに倣った四角形の開口部３ｅをエッチング用マスクに形成するが、開口部３ｅの対向する二辺の幅および開口部３ｅの間隔については、第１の実施形態で示した表１のような、上記開口部３ｅの幅および間隔と形成される液晶配向膜の凹部の幅との関係を示す表を予め作成し、作成した表に基づいて形成される液晶配向膜の凹部の幅から決定する。
【０２４６】
この後、エッチャント４としてフッ酸系エッチング液を用いて配向膜１１のエッチングを行う。図１３（Ｃ）はエッチングの初期段階の状態を示した断面図である。
【０２４７】
エッチングが始まると、配向膜１１の等方性エッチングが進行し、微小な溝部が形成される。この微小な溝部中の配向膜表面に、エッチングにより生じた、エッチャント４に対する不溶物５であるフッ化アルミニウム等が蓄積し、配向膜１１のエッチングの進行を阻害し、最終的にはエッチングが停止する。
【０２４８】
次に、レジスト３の剥離を行って不溶物５を洗い流すと、図１３（Ｄ）に示すように、溝部と直線状突部とが交互に複数設けられた液晶配向膜１１ａが形成される。
【０２４９】
本実施形態では、配向膜１１にエッチャント４に対する不溶物５を生成する物質として酸化アルミニウム等が含まれ、エッチングによりエッチャント４に対する不溶物５が生成されるため、ある程度エッチングが進行した状態でエッチングが自動的に停止し、大面積の基板上に作製する場合でも均一な凹凸形状を有する液晶配向膜を安価に作製することができる。また、各エッチング処理におけるエッチング量のばらつきがなく、エッチング処理間におけるパターン形状が均一な液晶配向膜を形成できる。
【０２５０】
また、上記不溶物５を生成させる酸化アルミニウム等を含有させる代わりに、配向膜１１にエッチャント４に溶解しない物質として、第１実施形態で述べたフッ化カルシウム等の物質から少なくとも一つ含有させるようにしてもよい。配向膜１１にエッチャント４に溶解しない物質を含有させることにより、この物質が上記不溶物５と同様の作用および効果を生じさせる。
【０２５１】
さらに、上記液晶配向膜１１が形成された基板１を２枚用いて、そのうちの１枚にシール材を印刷した後２枚の基板１を貼り合せてパネル化し、パネル内に液晶を注入して液晶表示素子とした。これにより、信頼性、均一性の高い液晶配向膜を、大面積に渡って安価に作製することができる。
【０２５２】
特に、上記配向膜１１として無機材料を用いることにより、液晶が注入される空間を仕切るための隔壁構造と組み合わせて用いた場合に、隔壁作製プロセスによる配向膜のダメージをなくすことができ、配向膜のダメージを受けやすいスメクティック液晶を使用した場合でも均一な配向を得ることができる。
【０２５３】
（第７の実施形態）
第７の実施形態は、本発明をワイヤーグリッド型の偏光光学素子の作製に適用する形態である。
【０２５４】
図１４は本発明の第７の実施形態を製造工程順に示した断面図である。
【０２５５】
図１４（Ａ）に示すように、基板１上に金属膜２０を形成する。なお、金属膜２０の材質としては、例えば、ＴｉとＡｌの合金等が使用可能であり、公知のスパッタ法等を用いて成膜する。
【０２５６】
次に、図１４（Ｂ）に示すように、第５の実施形態と同様な方法を用いて、エッチング用マスクをレジスト３で形成するが、四角形の開口部３ｆの長手方向は透過させる偏光方向と直交させておく。
【０２５７】
なお、形成される偏光光学素子のパターンに倣った四角形の開口部３ｆをエッチング用マスクに形成するが、開口部３ｆの対向する二辺の幅および開口部３ｆの間隔については、第１の実施形態で示した表１のような、上記開口部３ｆの幅および間隔と形成される偏光光学素子の凹部の幅との関係を示す表を予め作成し、作成した表に基づいて形成される偏光光学素子の凹部の幅から決定する。
【０２５８】
この後、フッ酸を含有させた金属膜エッチャント４０を用いて金属膜２０のエッチングを行う。図１４（Ｃ）はエッチングの初期段階の状態を示した断面図である。
【０２５９】
エッチングが始まると、金属膜２０の等方性エッチングが進行し、微小な溝部が形成される。この微小な溝部中の金属膜表面に、エッチングにより生じたエッチャント４に対する不溶物５であるフッ化アルミニウムが蓄積し、金属膜２０のエッチングの進行を阻害し、最終的にはエッチングが停止する。
【０２６０】
その後、レジスト３の剥離を行って不溶物５を洗い流すと、図１４（Ｄ）に示すように、溝部と金属線とが交互に複数設けられた、ワイヤーグリッド型の偏光光学素子２０ａを得る。
【０２６１】
本実施形態では、金属膜２０にエッチャント４に対する不溶物５を生成する物質であるアルミニウムが含まれ、エッチングによりエッチャント４に対する不溶物５が生成されるため、ある程度エッチングが進行した状態でエッチングが自動的に停止し、大面積の基板上に作製する場合でも金属線パターンの均一なワイヤーグリッド型偏光光学素子を安価に作製することができる。また、各エッチング処理におけるエッチング量のばらつきがなく、エッチング処理間におけるパターン形状が均一な偏光光学素子を形成できる。
【０２６２】
また、開口部３ｆからのエッチングが基板１に達したときにレジスト３下における金属膜２０のサイドエッチングが停止する条件を用いることで、レジスト３下における金属膜２０のオーバーエッチングを防止することができる。
【０２６３】
なお、上記金属膜２０に、マグネシウム、カルシウム、カリウム、ストロンチウム、バリウム、リチウム、ナトリウム、セシウム、亜鉛、および鉛の物質のうち少なくとも一つを含有するようにしてもよい。これらの物質は、上記アルミニウムと同様に、フッ酸と反応して上記不溶物５を生成する。
【０２６４】
（第８の実施形態）
第８の実施形態は、本発明を等方性エッチング法による、マイクロ化学分析システムやＬＯＣに使用されるマイクロチップのパターン作製に適用する形態である。
【０２６５】
図１５は基板表面に作製された、マイクロチップの凹部パターンを示す上面図である。
【０２６６】
図１５に示すように、マイクロチップの基板１の表面には、薬品が注入される試薬槽１５と、各種薬品を混合させて反応をさせる反応槽１６と、試薬槽１５から反応槽１６に薬品が移動するためのマイクロチップ用液出路１４とが設けられている。
【０２６７】
上記マイクロチップ用液出路１４の作製方法について以下に説明する。
【０２６８】
図１６は本発明の第８の実施形態を製造工程順に示した断面図である。なお、図１６に示す部分は、図１５に示した破線部分ＹＹ’の断面である。
【０２６９】
図１６（Ａ）に示すように、基板１として、第１の実施形態と同様に、酸化アルミニウム等を均一に含有する無アルカリガラスを用いて、この基板１上に、マイクロチップ用液出路を形成するための、金属膜２およびレジスト３からなるエッチング用マスクを形成する。
【０２７０】
なお、マイクロチップ用液出路１４のパターンに倣った四角形の開口部３ｇをエッチング用マスクに形成するが、開口部３ｇの対向する二辺の幅については、第１の実施形態で示した表１のような、上記開口部３ｇの幅と形成されるマイクロチップ用液出路１４の幅との関係を示す表を予め作成し、作成した表に基づいて形成されるマイクロチップ用液出路１４のパターンの幅から決定する。
【０２７１】
次に、エッチャント４としてフッ酸系エッチング液を用いて基板１のエッチングを行う。図１６（Ｂ）はエッチングの初期段階の状態を示した断面図である。
【０２７２】
エッチングが始まると、上記開口部３ｇより基板１の等方性エッチングが進行し、微小な溝部が形成される。この微小な溝部中の基板表面に、エッチングにより生じた、エッチャントに対する不溶物５であるフッ化アルミニウム等が蓄積し、基板１のエッチングの進行を阻害し、最終的にはエッチングが停止して液出路パターンが形成される（図１６（Ｃ））。
【０２７３】
金属膜２およびレジスト３とともに不溶物５を除去した後、マイクロチップ用液出路１４を得る（図１６（Ｄ））。
【０２７４】
なお、上述した作製方法により、試薬槽１５および反応槽１６についても、上記マイクロチップ用液出路１４と同様に、不溶物５が蓄積されることでパターンが形成される。
【０２７５】
マイクロチップ用液出路１４のパターン間隔を狭くしてパターン集積度を大きくする場合には、開口部３ｇの対向する二辺の幅および開口部３ｇの間隔について、上記第１実施形態と同様に、開口部３ｇの対向する二辺の幅および開口部３ｇの間隔と、マイクロチップ用液出路１４の幅との関係を示す表を作成し、形成されるマイクロチップ用液出路１４の幅から決めればよい。
【０２７６】
また、本実施形態では、マイクロチップ用パターンの作製方法として、上記マイクロチップ用液出路１４のパターンについて説明したが、試薬槽１５および反応槽１６のパターンについても、本実施形態を適用することができる。その際、マイクロチップ用パターンが四角形に限らず八角形なども含む多角形であれば、上記開口部３ｇの対向する二辺の幅を開口部３ｇの最大幅に替えて、開口部３ｇの最大幅と形成されるマイクロチップ用パターンの幅との関係を示す表を予め作成し、作成した表に基づいて形成されるマイクロチップ用パターンの幅から開口部３ｇの最大幅を決定すればよい。
【０２７７】
本実施形態では、基板１にエッチャント４に対する不溶物５を生成する物質として酸化アルミニウム等が含まれ、エッチングによりエッチャント４に対する不溶物５が生成されるため、ある程度エッチングが進行した状態でエッチングが自動的に停止し、大面積の基板でも均一なマイクロチップ用パターンを安価に作製することができる。また、各エッチング処理におけるエッチング量のばらつきがなく、エッチング処理間における凹部形状が均一なマイクロチップ用パターンを形成できる。
【０２７８】
また、第１の実施形態で述べたように、基板１がオキシハライドガラスであれば、フッ酸系エッチング液に溶解しない物質としてフッ化カルシウム等が含有されるため、フッ化カルシウム等が上記不溶物５と同様な作用および効果を生じさせる。
【０２７９】
なお、本発明は、以上説明したような第１の実施形態から第８の実施形態における微細構造の形成用途に限定されるものではなく、大構造を形成する場合でも、エッチング量を制御し、形成されるパターン形状の均一性を向上する目的で使用することができる。大構造を形成する場合でも、エッチャントに対する不溶物が被エッチング体の表面に蓄積して、エッチングの進行を停止させることができるからである。
【０２８０】
また、等方性エッチングだけでなく、エッチングにある程度の異方性がある場合でも、上述したように、エッチング液に不溶な物質を生成させることでエッチングを停止させ、形成されるパターン形状の均一性を向上する目的で使用することができる。
【０２８１】
【発明の効果】
本発明は以上説明したように構成されているので、以下に記載する効果を奏する。
【０２８２】
本発明の等方性エッチング法を用いた微細構造形成方法を用いて得られる微細構造について、大型の基板について複数枚のエッチング処理に本発明を使用した場合でも、基板面内のみならず基板間でも均一性の高い微細構造を作製することができる。また、比較的安価な液晶表示素子用ガラスを使用できるため、低コスト化が可能になる。
【０２８３】
さらに、本発明を２Ｐ成型法における母型の作製に使用することで、大型の母型を高い歩留まりで安価に作製することが可能となるばかりでなく、母型と同種の基板を使用することで熱膨張係数の違いに起因する誤差を小さくすることができ、厳密な温度管理が不要になる。大型の母型が使用できるため、低コスト化が可能となる。
【図面の簡単な説明】
【図１】本発明の第１の実施形態を製造工程順に示した断面図である。
【図２】第１の実施形態により作製されたマイクロレンズアレイ基板１２を用いた液晶表示素子の外観を模式的に示す斜視図である。
【図３】第１の実施形態により作製されたマイクロレンズアレイ基板を用いた液晶表示素子の作製方法を製造工程順に示した断面図である。
【図４】第１の実施形態により作製されたマイクロレンズアレイ基板を用いた液晶表示素子の作製方法を製造工程順に示した断面図である。
【図５】第１の実施形態により作製されたマイクロレンズアレイ基板を用いた液晶表示素子の作製方法を製造工程順に示した断面図である。
【図６】第１の実施形態により作製されたマイクロレンズアレイ基板を用いた液晶表示素子について別の構成例を示す断面図である。
【図７】図２に示した液晶表示素子を用いた液晶プロジェクタの一構成例を示す模式図である。
【図８】図２に示した液晶表示素子を用いた半透過型の液晶表示装置の外観を模式的に示す斜視図である。
【図９】本発明の第２の実施形態を製造工程順に示した断面図である。
【図１０】本発明の第３の実施形態を製造工程順に示した断面図である。
【図１１】本発明の第４の実施形態を製造工程順に示した断面図である。
【図１２】本発明の第５の実施形態を製造工程順に示した断面図である。
【図１３】本発明の第６の実施形態を製造工程順に示した断面図である。
【図１４】本発明の第７の実施形態を製造工程順に示した断面図である。
【図１５】本発明の第８の実施形態により作製されるマイクロチップの凹部パターンを示す上面図である。
【図１６】本発明の第８の実施形態を製造工程順に示した断面図である。
【図１７】従来の２Ｐ成型法を用いたマイクロレンズアレイの製造工程を説明するための断面図である。
【図１８】従来の転写法を用いたマイクロレンズアレイの製造工程を説明するための断面図である。
【図１９】従来の等方性エッチング法を用いたマイクロレンズアレイの製造工程を説明するための断面図である。
【符号の説明】
１、３０、２０１ 基板
１ａ、２０１ａ 柱状パターン
２、２０、２０２ 金属膜
３、２０３ レジスト
３ａ、３ｂ、３ｃ、３ｄ、３ｅ、３ｆ、３ｇ、２０３ａ 開口部
４ エッチャント
５ 不溶物
６、１１４ 母型
７、１０７ 離型剤
８、１０８ 樹脂
９ 配線用金属層
９ａ 埋め込み配線
１０ 透明電極
１１ 配向膜
１１ａ 液晶配向膜
１２、２１２ マイクロレンズアレイ基板
１３ 光導波路
１４ マイクロチップ用液出路
１５ 試薬槽
１６ 反応槽
２０ａ 偏光光学素子
３２、１１２、１２０、１２２ マイクロレンズアレイ
３４ 回折格子
４０ 金属膜エッチャント
５０、２５０ａ ＴＦＴ基板
５１、２５１ 調整用ガラス板
５２、２５２ 液晶層
１００ ガラス基板
１０４ ウェットエッチング液
１１５ 熱変形性パターン
１１５ａ 半球状パターン
１１６ マスク層
１１７ 石英ガラス基板
１３０ 光源
１３１ リフレクタ
１３２ 偏光変換インテグレータ
１３３、１３４ ダイクロイックミラー
１３５、１３６、１３７ 全反射ミラー
１３８ 赤色用液晶表示素子
１３９ 緑色用液晶表示素子
１４０ 青色用液晶表示素子
１４１ クロスダイクロイックプリズム
１４２ 投射レンズ
１５１、２６０ 液晶表示素子
１５２、１５３ 偏光板
１５４ バックライトユニット
１５５ 信号供給回路
１５６ 電源供給部
２０３ｂ 露光位置調整マーカ
２１２ａ 個片にしたマイクロレンズアレイ基板
２５０ａ 個片にしたＴＦＴ基板
２５３ 保護材
２５４ 高屈折率接着剤
２５５ 重ね合わせ位置調整マーカ
２５６ 画素遮光部
２５７ ＴＦＴ基板側重ね合わせ位置調整マーカ
２５８ シール剤[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microstructure forming method using an isotropic etching method, a microlens array substrate, a matrix for a microlens array, a liquid crystal display element, a liquid crystal display device, and a liquid crystal projector.
[0002]
[Prior art]
Along with the progress of the fine structure forming technology in recent years, many attempts have been made to introduce a fine structure into an existing element to achieve high functionality, high performance, and high added value. In particular, recently, it is becoming possible to process a scale close to the wavelength of light, so these attempts are promising in the field of optical elements and display elements.
[0003]
As an example, in the field of liquid crystal display elements, a technique for providing a microlens array of a pixel size on a glass substrate is being studied. This is because the aperture ratio of the liquid crystal display element is inevitably limited by the presence of wiring and electrodes for driving the display pixels. In particular, in an active matrix type liquid crystal display element using a thin film transistor (TFT), a typical aperture ratio is about 60% or less. Therefore, an attempt is made to realize bright display and low power consumption by providing a microlens array on the substrate on which light is incident and concentrating incident light on the opening to improve the effective aperture ratio. ing. Such attempts are particularly emphasized in applications where there is a great demand for brightness and power consumption.
[0004]
For example, in a liquid crystal projector, in order to realize a clear display even in a bright environment, it is very important to improve the brightness, and mounting a microlens array on a liquid crystal panel used as a light valve is being studied. . In such an application, it is necessary to produce a large number of microlenses of at least the number of pixels.
[0005]
As a method for producing a microlens array, a method using a 2P molding method is disclosed (for example, see Patent Document 1). FIG. 17 is a cross-sectional view illustrating this method for each process. A method for manufacturing a microlens array will be described with reference to FIG. First, a glass substrate 100, a matrix 114 having a plurality of substantially hemispherical concave portions formed on the molding surface, a release agent 107, and an uncured resin 108 are prepared, as shown in FIG. A mold release agent 107 and an uncured resin 108 are applied to the molding surface side of the mother die 114. Next, the surface of the resin 8 and the surface of the glass substrate 100 are aligned, the mother die 114 is pressed against the glass substrate 100 side, and the uncured resin 108 is press-molded on the molding surface of the mother die 114 (FIG. 17 ( B)). Thereafter, the resin 108 is cured with ultraviolet rays or the like, and the microlens array 112 including a resin lens layer is formed on a glass substrate (FIG. 17C).
[0006]
As another example of the 2P molding method, a method of using a silicon substrate having excellent workability and flatness as a mother die is disclosed (for example, see Patent Document 2).
[0007]
As another example of a method for manufacturing a microlens array, a transfer method using heating and dry etching in combination is disclosed (for example, see Patent Document 3). FIG. 18 is a cross-sectional view illustrating this method for each process. A method for manufacturing a microlens array will be described with reference to FIG. As shown in FIG. 18A, after a heat-deformable pattern 115 made of a heat-deformable material is formed on a glass substrate 100, a substantially hemispherical hemispherical pattern 115a is produced using pattern deformation by a heating process. (FIG. 18B). Next, the glass substrate 100 is dry-etched using the hemispherical pattern 115a as a mask to transfer a substantially hemispherical convex shape to the glass substrate 100, thereby producing a microlens array 120 (FIG. 18C).
[0008]
Further, a method for forming a microlens array using an isotropic etching method is disclosed (for example, see Patent Document 4). FIG. 19 is a cross-sectional view illustrating this method for each process. A method for forming a microlens array will be described with reference to this drawing. First, an etching mask layer 116 made of silicon is formed on the surface of the quartz glass substrate 117 (FIG. 19A). Next, as shown in FIG. 19B, isotropic etching with the wet etching solution 104 is performed on the quartz glass substrate 117. After that, the mask layer 116 is peeled off to form the microlens array 122 (FIG. 19C).
[0009]
As described above, many studies have been made on microlens arrays for liquid crystal projectors.
[0010]
In addition to projector applications, attempts have been made to apply microlens arrays to transflective liquid crystal display elements. Disclosed is a method for effectively utilizing backlight light during transmission display and reducing power consumption by providing a microlens array that condenses backlight light at a minute opening of a reflector (for example, , See Patent Document 5).
[0011]
Another example to which the fine structure forming technique is applied is an optical waveguide. An optical switch or an arrayed waveguide grating multiplexer / demultiplexer is realized by providing a large number of waveguides and 3 dB couplers on a quartz glass substrate (see, for example, Non-Patent Document 1). These optical switches and demultiplexers are used for wavelength separation of multiplexed light and optical add / drop in the wavelength division multiplexing communication system, but there is a limit to miniaturization due to the loss of the waveguide and the characteristics of wavelength separation. In particular, since the number of multiplexed wavelengths is expected to increase in the future, as a result, an increase in area tends to be unavoidable.
[0012]
Further, an attempt to improve the display performance of the liquid crystal display element by embedding the wiring of the liquid crystal display element in the substrate to reduce the unevenness on the surface of the substrate and to make the alignment of the liquid crystal uniform (for example, patent document) is disclosed. 6).
[0013]
Attempts have also been made to form a diffraction grating having a periodic structure of a wavelength on a substrate by a fine structure forming technique. In particular, a method is disclosed in which a diffraction grating is formed on a substrate of an organic electroluminescence element to improve the light extraction efficiency from the light emitting layer (see, for example, Patent Document 7).
[0014]
In addition, alignment film formation of a liquid crystal display element using a fine structure forming technique is disclosed (for example, see Patent Document 8). Currently, the most frequently used liquid crystal alignment method is a rubbing method in which an organic film such as polyimide is rubbed with a cloth such as cotton. However, in this rubbing method, the organic film is easily scratched, so that the display quality is deteriorated, it is contaminated with dust generated from cotton cloth, etc., and the reliability is low. Therefore, attempts have been made to align liquid crystals by forming a fine groove structure of about submicron in an inorganic film or the like.
[0015]
In addition, studies for forming a polarization-dependent optical element have been conducted. In order to give the optical element a polarization-dependent function, there are a method of using an optical material having polarization anisotropy and a method of forming a hyperfine structure in an isotropic material and using structural birefringence. In particular, the latter has recently attracted particular attention with the progress of the fine processing technology at the applied wavelength level (see, for example, Non-Patent Document 2).
[0016]
In addition, a fine structure having a size of about a micrometer to several tens of micrometers is produced on a substrate by a fine structure forming technique, and the produced fine structure is converted into a micro chemical analysis system (μTAS: Micro Total Analysis Systems) or LOC. Microchips for use in (Laboratory on a Chip) are being considered. In particular, in recent years, it has been actively applied to DNA analysis, medical care, and environmental fields (for example, see Non-Patent Document 3).
[0017]
As described above, the range in which the fine structure forming technique can be applied is very wide, and various studies have been made.
[0018]
[Patent Document 1]
JP 2001-201609 A
[Patent Document 2]
JP 2001-246599 A
[Patent Document 3]
Japanese Patent Laid-Open No. 2001-074913
[Patent Document 4]
JP 2001-147305 A
[Patent Document 5]
JP 2000-298267 A
[Non-Patent Document 1]
Kenichi Yukimatsu “Optical Switching and Optical Interconnection”, Kyoritsu Publishing Co., Ltd., p. 137-139
[Patent Document 6]
JP-A-6-82832
[Patent Document 7]
Japanese Patent Laid-Open No. 11-283951
[Patent Document 8]
JP 2000-81625 A
[Non-Patent Document 2]
Applied Optics Vol. 39, no. 20, 2000
[Non-Patent Document 3]
"Nanotechnology and Polymers" edited by Polymer Society, p. 117-131
[0019]
[Problems to be solved by the invention]
However, in forming a fine structure, improvement of the shape uniformity is the biggest issue. In consideration of mass productivity, low cost, and high yield, a multi-planar technique is required in which an inexpensive material is used to collectively manufacture a large substrate and make a small piece after completion. However, using a large substrate makes it more difficult to achieve uniformity.
[0020]
For example, in the microlens array in the liquid crystal projector, as described above, the 2P molding method, the transfer method using the dry etching method, and the isotropic etching method have been studied, and problems of these methods will be described below. .
[0021]
In terms of fabrication of a fine structure on a large substrate, the 2P molding method requires that a large-scale mother die having a fine structure must be prepared, and that the material of the mother die differs from the substrate due to a difference in thermal expansion coefficient. There are problems, for example, that strict temperature management is required because deformation occurs, and that precise control in the height direction is required when embossing. These problems can be solved, for example, by preparing a small mother die and sequentially pressing the substrate many times, but the lateral position control must be performed precisely. New problems also occur.
[0022]
Further, although the above-described dry etching method is excellent in in-plane uniformity, it is necessary to prepare a large dry etching apparatus and a large vacuum tank in order to process a large substrate. In general, a large apparatus is expensive, which is disadvantageous for cost reduction. In addition, in principle, the number of substrates that can be processed in one process is limited to one, and since the processing is performed in a vacuum, the vacuum operation takes time and the mass productivity is lowered.
[0023]
On the other hand, in the above isotropic etching method, a large etching tank for wet etching is prepared, so that it is possible to cope with a large substrate relatively easily. Further, since a plurality of sheets can be processed at the same time, it is advantageous in terms of cost reduction. However, when a quartz glass substrate or a silicon substrate is used, since it is difficult to control the etching amount by wet etching, there is a problem that unevenness is likely to occur in the surface and variation among lots occurs. Further, when the support of the etching mask is lost as the etching progresses, the mask is peeled off during etching, which causes etching unevenness. Furthermore, since an expensive quartz glass substrate or silicon substrate is used, there is a problem that cost reduction is difficult.
[0024]
Such a problem occurs not only in a microlens array for a liquid crystal projector but also in a microlens array for a transflective liquid crystal display element when the above manufacturing method is employed.
[0025]
The same kind of problem as described above also occurs in optical waveguides, embedded wirings, diffraction gratings, liquid crystal alignment films having fine grooves, polarization-dependent optical elements, and microchips that use fine structure forming technology. As described above, in microfabrication using isotropic etching, it is difficult to control etching, and it is difficult to ensure in-plane uniformity particularly when the size is increased, and there is a problem that costs increase. In addition, when dry etching is used, a large-sized apparatus is required, and there is only one substrate that can be processed in a single process, and a vacuum operation is required, so that the process takes time and costs increase. There is a point.
[0026]
The present invention has been made to solve the problems of the conventional techniques as described above, and improves the controllability of etching during microfabrication using isotropic etching, and is uniform even on large substrates. A fine structure forming method that realizes simple processing, a microlens array substrate manufactured by the fine structure forming method of the present invention, and a liquid crystal display element, a liquid crystal display device, and a liquid crystal projector using the microlens array substrate The purpose is to do. Another object of the present invention is to provide a method for forming a fine structure in which a large matrix using the same kind of material as that of a substrate is manufactured at a high yield and at a low cost, and strict temperature control is not required.
[0027]
[Means for Solving the Problems]
In order to achieve the above object, the microstructure forming method of the present invention etches the object to be etched from the opening using an etching solution on the object to be etched provided with a mask having a predetermined opening. A fine structure forming method for forming a recess in the surface of the object to be etched,
Insoluble matter is generated by a reaction between the substance contained in the object to be etched and the etching solution,
Etching is stopped by the insoluble matter accumulated on the exposed surface of the object to be etched.
[0028]
In this case, the object to be etched may contain at least one of aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, strontium oxide, barium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, and lead oxide. Good.
[0029]
Further, the fine structure forming method of the present invention etches the object to be etched from the opening using an etching solution on the object to be etched provided with a mask having a predetermined opening on the surface, and the surface of the object to be etched A method for forming a microstructure in which a recess is formed,
Leaching the substance from the object to be etched containing a substance that does not dissolve in the etchant;
Etching is stopped by the substance accumulated on the exposed surface of the object to be etched.
[0030]
In this case, the object to be etched may include at least one of calcium fluoride, sodium fluoride, barium fluoride, aluminum fluoride, strontium fluoride, and magnesium fluoride.
[0031]
In this case, the etching solution may contain hydrofluoric acid.
[0032]
In any one of the fine structure forming methods of the present invention, the fine structure may be a microlens.
[0033]
In this case, the opening provided in the mask is circular,
Create a table showing the relationship between the diameter of the opening and the diameter of the recess formed corresponding to the diameter of the opening,
The diameter of the opening corresponding to the desired recess diameter may be formed in the mask according to the table.
[0034]
In any one of the above-described fine structure forming methods of the present invention, the fine structure may be used in a microlens array in which concave portions are continuously formed.
[0035]
In this case, the opening provided in the mask is circular,
Create a table showing the relationship between the diameter and spacing of the opening and the diameter of the recess formed corresponding to the diameter and spacing of the opening,
According to the table, the diameter and the interval of the opening corresponding to the desired recess diameter may be formed in the mask.
[0036]
In this case, the diameter of the opening may be 1/3 or less of the interval between the openings, and the diameter of the opening may be 1/10 or more of the interval between the openings.
[0037]
In this case, the opening provided in the mask is a quadrangle,
Create a table showing the relationship between the width of the two opposite sides of the opening and the interval between the openings, and the width of the recess formed corresponding to the width and interval of the openings,
According to the table, the width and interval of the opening corresponding to the desired recess width may be formed in the mask.
[0038]
Further, in this case, the width of the two opposite sides of the opening may be 1/3 or less of the interval between the openings, and the width of the two opposite sides of the opening is 1/10 of the interval between the openings. It may be the above.
[0039]
In the case where the fine structure according to any of the fine structure forming methods of the present invention is used in a microlens array in which concave portions are continuously formed, the object to be etched is a glass substrate,
The mask may be composed of a metal film and an organic film sequentially formed on the surface of the glass substrate.
[0040]
In this case, the thickness of the metal film may be 20 nm to 300 nm, and the thickness of the organic film may be 200 nm to 4000 nm.
[0041]
Further, in any one of the fine structure forming methods of the present invention, an alignment means may be provided on the surface of the object to be etched, and a protective material may be formed to protect the alignment means from the etching solution. The matching means may be manufactured in the same process as the mask having the opening.
[0042]
In any of the above-described fine structure forming methods of the present invention, the fine structure may be an optical waveguide pattern, or the fine structure may be a buried wiring pattern.
[0043]
In this case, the opening provided in the mask is square,
Create a table showing the relationship between the width of the two opposite sides of the opening and the width of the recess formed corresponding to the width of the opening,
According to the table, the width of the opening corresponding to the desired recess width may be formed in the mask.
[0044]
In any of the above-described fine structure forming methods of the present invention, the fine structure may be a diffraction grating, or the fine structure may be a liquid crystal alignment film.
[0045]
In the fine structure forming method of the present invention, the fine structure may be a polarizing optical element.
[0046]
In this case, the object to be etched may contain at least one of aluminum, magnesium, calcium, potassium, strontium, barium, lithium, sodium, cesium, zinc, and lead. In this case, the etching solution may contain hydrofluoric acid.
[0047]
In any one of the above-described fine structure forming methods of the present invention, the fine structure may be a microchip pattern.
[0048]
In this case, the opening provided in the mask is a polygon,
Create a table showing the relationship between the maximum width of the opening and the width of the recess formed corresponding to the maximum width of the opening,
The maximum width of the opening corresponding to the desired recess width may be formed in the mask according to the table.
[0049]
In this case, the opening provided in the mask is a quadrangle,
Create a table showing the relationship between the width of the two opposite sides of the opening and the interval between the openings, and the width of the recess formed corresponding to the width and interval of the openings,
According to the table, the width and interval of the opening corresponding to the desired recess width may be formed in the mask.
[0050]
In addition, the microlens array substrate of the present invention has a recess formed by any one of the above-described fine structure forming methods of the present invention when the fine structure is used in the microlens array.
[0051]
The matrix for a microlens array of the present invention has a recess formed by any one of the above-described microstructure forming methods of the present invention when the microstructure is used in a microlens array.
[0052]
Further, the microlens array substrate of the present invention is provided with alignment means by the fine structure forming method of the present invention and has a light shielding means.
[0053]
Further, the matrix for microlens array of the present invention for achieving the above object is a matrix for microlens array having a recess,
The structure includes at least one of aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, strontium oxide, barium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, and lead oxide. In this case, it is good also as having a columnar pattern around a lens.
[0054]
Further, the microlens array substrate of the present invention for achieving the above object is a microlens array substrate having a concave portion to be a lens,
The structure includes at least one of aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, strontium oxide, barium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, and lead oxide. In this case, it is good also as having a columnar pattern around a lens.
[0055]
In the microlens array substrate of the present invention, a material having a higher refractive index than that of the microlens array substrate may be embedded in the recess, or a transparent substrate may be provided on the recess forming surface side.
[0056]
The microlens array substrate of the present invention may have an alignment unit or a light shielding unit.
[0057]
The liquid crystal display element of the present invention uses the microlens array substrate of the present invention.
[0058]
In the liquid crystal display element of the present invention, the microlens array substrate and the substrate sandwiching the liquid crystal between the microlens array substrate may be non-alkali glass or a quartz substrate.
[0059]
Furthermore, the liquid crystal display device of the present invention uses the liquid crystal display element of the present invention, and the liquid crystal projector of the present invention uses the liquid crystal display element of the present invention.
[0060]
(Function)
In the present invention, since the insoluble matter generated by the reaction between the substance contained in the object to be etched and the etching solution accumulates on the exposed surface of the object to be etched and stops the etching, the etching object is removed after the etching is stopped. Etching does not proceed even when immersed in the substrate. Therefore, even when a plurality of microstructures are formed on a large-scale object to be etched, the insoluble matter is generated uniformly on the exposed surface of the object to be etched. In addition, even when a plurality of objects to be etched are processed at a time, the generation of the insoluble matter is uniform between the objects to be etched, so that uniform processing can be performed between the objects to be etched. Furthermore, even when a single object to be etched is processed by a plurality of etching processes, the generation of the insoluble matter is uniform between the etching processes, so that uniform processing can be performed between the etching processes.
[0061]
Further, in the present invention, instead of the insoluble material, the substance contained in the object to be etched that does not dissolve in the etching solution accumulates on the exposed surface of the material to be etched and stops the etching. Cause it to occur.
[0062]
In the present invention, an object to be etched containing at least one of aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, strontium oxide, barium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, and lead oxide is provided. When etching with an etching solution containing hydrofluoric acid, aluminum fluoride, magnesium fluoride, calcium fluoride, potassium fluoride, strontium fluoride, barium fluoride, lithium fluoride, fluorine fluoride, which are insoluble in the etching solution containing hydrofluoric acid, are used. Since any one of sodium fluoride, cesium fluoride, zinc fluoride, and lead fluoride is produced as the insoluble matter, these cause the same action as the insoluble matter.
[0063]
Further, when an object to be etched containing at least one of calcium fluoride, sodium fluoride, barium fluoride, aluminum fluoride, strontium fluoride, and magnesium fluoride is etched with an etchant containing hydrofluoric acid, these are Since they are substances that do not dissolve in the etching solution containing hydrofluoric acid, they cause the same action as the insoluble matter.
[0064]
In the present invention, since the microstructure is a microlens, the shape of the formed lens does not change even if the object to be etched is further immersed in an etching solution after the etching is stopped by the insoluble matter. Therefore, there is no variation in the etching amount in each etching process, and a microlens having a uniform lens shape between etching processes can be manufactured. Further, even when a plurality of lenses are formed on a large substrate as an object to be etched, the generation of the insoluble matter is uniform on the exposed surface of the substrate, so that it becomes possible to produce a microlens having a uniform lens shape within the substrate surface. .
[0065]
In the present invention, the mask is provided corresponding to the desired recess diameter by using a table showing the relationship between the diameter of the circular opening and the diameter of the recess formed corresponding to the diameter of the opening. The diameter of the opening is obtained, and a desired recess can be formed on the surface of the object to be etched.
[0066]
Further, in the present invention, since the fine structure is used in a microlens array in which concave portions are continuously formed, after the etching is stopped by the insoluble matter, the object to be etched is further immersed in an etching solution. The shape of the formed lens does not change. Therefore, there is no variation in the etching amount in each etching process, and a microlens array with a uniform lens shape between etching processes can be manufactured. In addition, even when a microlens array is formed on a large substrate as an object to be etched, the generation of the insoluble matter is uniform on the exposed surface of the substrate, so that it is possible to produce a microlens array with a uniform lens shape within the substrate surface. Become.
[0067]
Furthermore, the insoluble matter generated in the progress of etching also plays a role of supporting the mask, thereby preventing the peeling of the mask.
[0068]
Further, in the present invention, a table showing the relationship between the diameter and interval of the circular opening and the diameter of the recess formed corresponding to the diameter and interval of the opening corresponds to the desired recess diameter. Thus, the diameter of the opening provided in the mask is obtained, and a desired concave lens can be continuously formed on the surface of the object to be etched.
[0069]
When the opening is a square, a table showing the relationship between the width of the two opposing sides of the opening and the interval between the openings and the width of the recess formed corresponding to the width and the interval of the opening is used. Thus, as in the case of the circular shape, a lens having a desired concave shape can be continuously formed on the surface of the object to be etched.
[0070]
As for the diameter of the mask opening, if the diameter of the opening is too small, the etching stops in a state where the etching does not proceed sufficiently. On the other hand, if the diameter of the opening is too large, the adjacent opening pattern overlaps with the etching region before the etching stops, and the mask peels off.
[0071]
Further, in the present invention, since the diameter of the opening is set to 1/3 or less of the interval between the openings, when the openings are too large, the etching regions of the openings are prevented from overlapping with each other to prevent the mask from peeling off. .
[0072]
Further, in the present invention, since the diameter of the opening is set to 1/10 or more of the opening interval, the phenomenon that the etching stops when the opening is too small and the etching does not proceed sufficiently is prevented.
[0073]
Note that the width of the two opposite sides of the opening when the mask opening is square is the same as the diameter when the opening is circular.
[0074]
As for the material of the mask, it is preferable that the etching solution hardly changes in quality and the adhesiveness with the glass substrate to be etched is high. This is because when the adhesion is low, etching proceeds from the interface between the glass substrate and the mask, which causes etching unevenness.
[0075]
In the present invention, since the metal film having good adhesion to the glass substrate is formed on the glass substrate surface, the progress of etching from the interface between the glass substrate and the metal film is prevented. In addition, since the organic film is formed on the surface of the metal film, the penetration of the etching solution into the surface of the glass substrate is prevented when the surface is damaged after the metal film is formed.
[0076]
In the present invention, the thickness of the metal film as a mask is set to a value between 20 nm and 300 nm so that pinholes generated when the metal film is too thin and cracks generated when the metal film is too thick are not generated. Therefore, the penetration of the etching solution from the pinhole and crack to the glass substrate is prevented.
[0077]
Further, in the present invention, since the thickness of the organic film is in the range of 200 nm to 4000 nm, the etching liquid from the scratches is generated when a minute scratch is generated on the surface of the metal film after the metal film is formed until the resist is applied. The film thickness is sufficient to prevent penetration, and more effectively prevent the etching solution from penetrating into the glass substrate.
[0078]
Further, in the present invention, since the alignment means is formed on the object to be etched and the protective material for protecting the alignment means is formed and then etching is performed, the shape change or peeling of the alignment means during etching is prevented. Can be prevented. Therefore, it is possible to align with the mask with high precision during exposure by using the alignment means after etching, patterning with less deviation from the underlying pattern, and high precision overlay with other substrates. Can be done.
[0079]
In the present invention, the number of steps can be reduced by manufacturing the alignment means and the mask having the opening in the same step.
[0080]
Further, in the present invention, since the fine structure is a pattern for an optical waveguide, the shape of the formed pattern does not change even if the object to be etched is further immersed in an etching solution after the etching is stopped by the insoluble matter. Therefore, there is no variation in the etching amount in each etching process, and it becomes possible to form an optical waveguide pattern having a uniform recess shape between etching processes. Further, even when the object to be etched is a large-area substrate, the insoluble matter is generated uniformly on the substrate surface, so that an optical waveguide pattern with a uniform recess shape can be formed.
[0081]
Further, in the present invention, since the fine structure is a pattern for embedded wiring, after the etching is stopped by the insoluble matter, the shape of the formed pattern does not change even if the object to be etched is further immersed in the etching solution. Therefore, there is no variation in the etching amount in each etching process, and it is possible to form a buried wiring pattern with a uniform recess shape between the etching processes. In addition, even when the object to be etched is a large-area substrate, the generation of the insoluble matter is uniform on the exposed surface of the substrate, so that it is possible to form a buried wiring pattern with a uniform recess shape in the substrate surface.
[0082]
Further, in the present invention, by using a table showing the relationship between the widths of two opposite sides of the rectangular opening and the width of the recess formed corresponding to the width of the opening, the desired recess width can be handled. Thus, the width of the opening provided in the mask is obtained, and a desired concave shape can be formed on the surface of the object to be etched.
[0083]
Further, in the present invention, since the fine structure is a diffraction grating, the shape of the formed diffraction grating does not change even if the object to be etched is further immersed in an etching solution after the etching is stopped by the insoluble matter. Therefore, there is no variation in the etching amount in each etching process, and a diffraction grating having a uniform pattern shape between etching processes can be formed. In addition, even when the object to be etched is a large-area substrate, the insoluble matter is generated uniformly on the substrate surface, so that it is possible to form a diffraction grating with a uniform pattern shape in the substrate surface.
[0084]
In the present invention, since the fine structure is a liquid crystal alignment film, after the etching is stopped by the insoluble matter, the shape of the formed liquid crystal alignment film does not change even if the object to be etched is further immersed in an etching solution. . Therefore, there is no variation in the etching amount in each etching process, and a liquid crystal alignment film having a uniform pattern shape between etching processes can be formed. In addition, even when the liquid crystal alignment film is formed with a large-area object to be etched, the generation of the insoluble material is uniform on the exposed surface of the object to be etched, so that it is possible to form a liquid crystal alignment film with a uniform in-plane pattern shape. Become.
[0085]
Further, in the present invention, since the microstructure is a polarizing optical element, after the etching is stopped by the insoluble matter, the shape of the formed polarizing optical element does not change even if the object to be etched is further immersed in an etching solution. . Therefore, there is no variation in the etching amount in each etching process, and a polarizing optical element having a uniform pattern shape between etching processes can be formed. In addition, even when a polarizing optical element is formed with a large-area object to be etched, the generation of the insoluble matter is uniform on the exposed surface of the object to be etched, so that it is possible to form a polarizing optical element with a uniform in-plane pattern shape. Become.
[0086]
Furthermore, since the insoluble matter hinders the progress of etching of the portion not covered with the mask, side etching to the object to be etched under the mask is prevented.
[0087]
In the present invention, when an object to be etched containing at least one of aluminum, magnesium, calcium, potassium, strontium, barium, lithium, sodium, cesium, zinc, and lead is etched with an etchant containing hydrofluoric acid, Aluminum fluoride, magnesium fluoride, calcium fluoride, potassium fluoride, strontium fluoride, barium fluoride, lithium fluoride, sodium fluoride, cesium fluoride, zinc fluoride, insoluble in an etching solution containing hydrofluoric acid, Since either one of lead and lead fluoride is produced as the insoluble matter, these cause the same action as the insoluble matter.
[0088]
In the present invention, since the microstructure is a microchip pattern, after the etching is stopped by the insoluble matter, the shape of the microchip pattern formed even when the object to be etched is further immersed in an etching solution is obtained. It does not change. Therefore, there is no variation in the etching amount in each etching process, and it is possible to form a microchip pattern with a uniform recess shape between etching processes. In addition, even when the object to be etched is a large-area substrate, the generation of the insoluble matter is uniform on the exposed surface of the substrate, so that it is possible to form a microchip pattern with a uniform recess shape in the substrate surface.
[0089]
Further, in the present invention, by using a table showing the relationship between the maximum width of the polygonal opening and the width of the recess formed corresponding to the maximum width of the opening, the desired recess width can be handled. Thus, the width of the opening provided in the mask is obtained, and a desired concave shape can be formed on the surface of the object to be etched.
[0090]
Further, in the present invention, a table showing the relationship between the widths of the two opposing sides of the rectangular opening and the interval between the openings and the width of the recess formed corresponding to the width and interval of the opening is used. Thus, the width and interval of the opening provided in the mask corresponding to the desired recess width can be obtained, and the desired recess shape can be continuously formed on the surface of the object to be etched.
[0091]
In addition, since the lens shape of the microlens array substrate of the present invention is uniform within the substrate surface, the distance from the substrate becomes uniform with respect to the focal point of the microlens within the substrate surface.
[0092]
In addition, since the microlens array matrix of the present invention has a uniform concave shape in the substrate surface, the microlens array substrate manufactured by molding using this matrix has a uniform lens shape in the substrate surface.
[0093]
Further, the microlens array substrate of the present invention exposes after aligning with the mask with higher accuracy using the alignment means, and the light shielding means is formed by patterning, so the overlap margin of the light shielding means is made smaller. It becomes possible to do. Therefore, if a liquid crystal display element is manufactured using this microlens array substrate, the aperture ratio can be increased and a brighter display can be realized.
[0094]
In addition, since the matrix for the microlens array of the present invention has a columnar pattern around the lens, the etching solution peels off the etching mask when an etching mask is formed on the columnar pattern. The columnar pattern prevents the lens shape from becoming uniform within the substrate surface.
[0095]
In addition, since the microlens array substrate of the present invention has a columnar pattern around the lens, the etching liquid peels off the etching mask when an etching mask is formed on the columnar pattern. Prevents the lens shape from becoming uniform within the substrate surface.
[0096]
In the microlens array substrate of the present invention, since a material having a higher refractive index than that of the microlens array substrate is embedded in the concave portion functioning as a lens, the focus of the microlens can be adjusted by adjusting the refractive index of the refractive index material. You can adjust the distance.
[0097]
In addition, the microlens array substrate of the present invention has a transparent substrate on the side of the concave formation surface that functions as a microlens array, so that the shape of the refractive index material embedded in the concave is maintained, and the light refracted in the concave is transparent. It can penetrate the substrate. In addition, the focal length of the microlens can be adjusted by adjusting the thickness of the transparent substrate.
[0098]
In addition, since the microlens array substrate of the present invention has alignment means, it is possible to align the pattern formed on the microlens array substrate with higher accuracy.
[0099]
Further, since the microlens array substrate of the present invention has a light shielding means, when the TFT substrate is superposed on the microlens array substrate, the light hitting the TFT can be reduced.
[0100]
In addition, since the liquid crystal display element of the present invention uses a microlens array substrate having a uniform lens shape within the substrate surface, the luminance within the element surface becomes uniform.
[0101]
Further, in the liquid crystal display element of the present invention, since the microlens array substrate and the substrate that sandwiches the liquid crystal between the microlens array substrate are non-alkali glass substrates or quartz substrates, both have the same thermal expansion coefficient and sandwich the liquid crystal. Substrate separation and misalignment that occur when the linear thermal expansion coefficients of two substrates are greatly different are suppressed, and reliability is further improved.
[0102]
In addition, since the liquid crystal display device of the present invention includes a liquid crystal display element using a microlens array substrate having a uniform lens shape within the substrate surface, the luminance in the display screen becomes uniform.
[0103]
Furthermore, since the liquid crystal projector of the present invention includes a liquid crystal display element using a microlens array substrate having a uniform lens shape within the substrate surface, the brightness of the entire projected image becomes uniform.
[0104]
DETAILED DESCRIPTION OF THE INVENTION
The present invention generates the insoluble matter by using an etching solution that reacts with a substance contained in the object to be etched to generate an insoluble matter, or an etching solution that does not dissolve a part of the substance contained in the subject to be etched. Or leaching the part of the substance to stop the etching.
[0105]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0106]
(First embodiment)
In the first embodiment, the present invention is applied to the production of a microlens array by isotropic etching.
[0107]
FIG. 1 is a sectional view showing a first embodiment of the present invention in the order of manufacturing steps.
[0108]
As the substrate 1, a non-alkali glass substrate having a thickness of 0.7 mm having a composition ratio of 49% silicon oxide, 10% aluminum oxide, 15% boron oxide, and 25% barium oxide is prepared. After cleaning the substrate 1, a metal film 2 made of a chromium layer having a thickness of 100 nm is formed on the substrate 1 by sputtering. Next, a resist 3 having a thickness of 1000 nm is formed on the metal film 2 by spin coating. For this resist 3, a positive resist was used. By exposing and developing the resist 3 using a stepper exposure machine, a plurality of circular openings 3a having a diameter of 3 μm are formed at a pitch of 30 μm.
[0109]
Next, the metal film 2 is etched using a known chromium etching solution mainly composed of ceric ammonium nitrate, the metal film 2 is processed into a shape similar to the shape of the opening 3a of the resist 3, and the etching is performed. A mask is formed (FIG. 1A). Here, the resist 3 is left as an etching mask without being peeled off. By leaving the resist 3, it is possible to reduce the influence on the substrate 1 due to the penetration of the etching solution from the scratch when the surface of the metal film is formed between the formation of the metal film and the application of the resist. is there.
[0110]
In addition, if the back surface and end surface of the substrate 1 are covered and protected by a protective material (not shown) such as a protective tape or an epoxy resin material, the metal film 2 or the resist 3, the thickness and size of the substrate 1 by etching are adjusted. Change can be reduced.
[0111]
Next, the substrate 1 is immersed in a 10% hydrofluoric acid aqueous solution to be the etchant 4 for 20 minutes, and the substrate 1 is etched.
[0112]
FIG. 1B is a cross-sectional view showing an initial stage state of etching.
[0113]
When the etching starts, isotropic etching of the substrate 1 proceeds from the opening 3a, and a roughly semispherical dent centered on the opening 3a is generated. By etching, aluminum fluoride and barium fluoride that are insoluble matter 5 with respect to the etchant 4 are mainly generated on the surface of the substrate in the minute depression. This insoluble matter 5 is generated by a reaction between aluminum oxide and barium oxide uniformly contained in the substrate 1 and hydrofluoric acid contained in the etchant 4.
[0114]
The insoluble matter 5 accumulates in the depression as the etching progresses, covers the substrate surface in the depression, and inhibits the circulation of the etchant 4. For this reason, the progress of the etching of the substrate 1 was gradually hindered, the etching stopped in about 15 minutes, and the etching did not proceed after that. FIG. 1C is a cross-sectional view showing this state.
[0115]
Thereafter, the shape of the depression does not change regardless of the etching time. In this embodiment, the etching is stopped when the etched region has reached a state where it overlaps with an adjacent lens. When attention is paid to one lens, columnar patterns 1a are formed at four locations around the lens.
[0116]
Thereafter, when the resist 3 is peeled off using acetone and the metal film 2 is peeled off using the chromium etching solution, the insoluble matter 5 containing aluminum fluoride as a main component is washed away from the depression. Further, when the protective material (not shown) is provided on the back surface and end surface of the substrate 1, the protective material (not shown) is peeled off to form a plurality of hemispherical lenses having a diameter of about 40 μm at a pitch of 30 μm. The obtained microlens array substrate 12 is obtained (FIG. 1D).
[0117]
In this embodiment, as described above, the substrate 1 is an object to be etched that uniformly contains aluminum oxide and barium oxide, which are substances that react with the etchant 4 to generate the insoluble matter 5 with respect to the etchant 4, Etchant 4 is an etching solution that reacts with aluminum oxide and barium oxide contained in substrate 1 to generate insoluble material 5 with respect to etchant 4. As a combination of the substrate 1 and the etchant 4, the substrate 1 includes alkali-free glass, low alkali glass, borosilicate glass, lead glass, β-quartz type transparent crystallized glass, aluminum oxide, magnesium oxide, and the like. Further, glass containing at least one of calcium oxide, potassium oxide, strontium oxide, barium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, and lead oxide can be used. As the etchant 4, hydrofluoric acid, a buffered hydrofluoric acid obtained by adding ammonium fluoride to hydrofluoric acid, or a hydrofluoric acid etching solution such as a hydrofluoric acid etching solution obtained by adding nitric acid to hydrofluoric acid can be used.
[0118]
Further, as insoluble matter 5, in addition to the above aluminum fluoride and barium fluoride, magnesium oxide, calcium oxide, strontium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, lead oxide react with hydrofluoric acid, respectively. , Magnesium fluoride, calcium fluoride, strontium fluoride, lithium fluoride, sodium fluoride, cesium fluoride, zinc fluoride, and lead fluoride are produced.
[0119]
Further, the substrate 1 and the etchant 4 may be combined such that the etchant 4 does not dissolve some of the substances contained in the substrate 1. As such a combination, oxyhalide glass can be used as the substrate 1, and the above hydrofluoric acid-based etching solution can be used as the etchant 4. Examples of substances that do not dissolve in the hydrofluoric acid-based etching solution include calcium fluoride, sodium fluoride, barium fluoride, aluminum fluoride, strontium fluoride, and magnesium fluoride. Since at least one substance that does not dissolve in the etchant 4 is included in the substrate 1, as the etching of the substrate 1 proceeds, the substance that does not dissolve in the etchant 4 covers the surface of the substrate 1, and the insoluble matter 5. Produces the same action and effect.
[0120]
In practicing the present invention, the opening diameter of the etching mask is an important factor for the following reasons. If the diameter of the opening is too small, the etching stops because the etching does not progress sufficiently and the circulation of the etchant 4 is hindered by the influence of the insoluble matter 5. If the opening diameter is too large, the circulation of the etchant 4 becomes difficult to be hindered. Therefore, before the etching is stopped by the insoluble matter 5, the adjacent microlens overlaps with the etching region, and the etching mask is peeled off to cause the etching. It will not stop. In addition, even when the pitch of the openings is too small, the etching region is overlapped with the adjacent microlens before the etching is stopped, and the etching mask is peeled off.
[0121]
From the above, a number of experiments were carried out by changing the opening diameter and opening pitch of the etching mask, and the results will be described.
[0122]
Table 1 summarizes the results of etching while changing the diameter of the circular openings and the pitch of the openings under the above production conditions. Note that the circles shown in Table 1 indicate that the progress of etching has stopped in a predetermined state. Further, a cross indicates that the progress of etching has not stopped, and a mark indicates that the etching has stopped in a state where the progress of etching has not sufficiently progressed.
[0123]
[Table 1]

[0124]
From the results shown in Table 1, it is apparent that the object of the present invention is achieved when the diameter of the opening is in the range of 1/10 to 1/3 of the pitch of the openings.
[0125]
In addition, the diameter of the microlens obtained by the circles shown in Table 1 ranges from the size of the state in which the adjacent lenses are in contact to the state in which the etching regions of the adjacent lenses overlap but the etching mask does not peel off. The size was 1.0 to 1.4 times the opening pitch shown in Table 1. From this result, by using Table 1, the pitch of the opening and the diameter of the opening can be determined from the diameter of the microlens to be manufactured. For example, in order to manufacture a microlens array having a lens diameter of 30 to 40 μm, it can be seen from Table 1 that when the pitch of the openings is set to 30 μm, the diameter of the openings may be set to 3 to 10 μm.
[0126]
In addition, many experiments were conducted when the shape of the opening was a square instead of a circle, and the results will be described.
[0127]
Table 2 summarizes the situation after etching by changing the side length of the opening, which is the length of one side of the square, and the pitch of the openings. The meaning of each mark shown in Table 2 is the same as in Table 1 above.
[0128]
[Table 2]

[0129]
From the results shown in Table 2, it is clear that the object of the present invention is achieved when the opening side length is in the range of 1/10 to 1/3 of the pitch of the openings. Thus, it has been found that the present invention does not greatly depend on the shape of the opening. Therefore, the shape of the opening 3a of the etching mask is circular in this embodiment, but it may be rectangular, elliptical, or other shapes.
[0130]
Next, in order to examine the dependency on the etchant concentration, the etching was carried out while changing the concentration of the hydrofluoric acid aqueous solution.
[0131]
Table 3 summarizes the etching time when the concentration of the hydrofluoric acid aqueous solution is 5%, 10%, 20%, and 30% when an etching mask having an opening pitch of 30 μm and an opening diameter of 3 μm is provided. Is. This etching time means the time until the etching progress automatically stops due to the influence of the insoluble matter 5.
[0132]
[Table 3]

[0133]
From the results shown in Table 3, the higher the concentration of hydrofluoric acid, the shorter the time required for the etching to stop. Further, when the lens shapes obtained under the respective etching conditions were observed, it was found that almost the same shape was obtained under any conditions. This suggests that the present invention does not depend greatly on the concentration of etchant 4. That is, even if the etchant concentration changes slightly, and the time until the etching stops varies due to this, the etching is automatically stopped by the insoluble matter 5, so that overetching does not occur. Moreover, it is possible to prevent insufficient etching by setting a time longer than a predetermined etching time in advance.
[0134]
As for the concentration of impurities contained in the substrate 1 that are not dissolved in the etchant 4, even when the etchant concentration is the same, if the impurity concentration is high, the progress of etching is accelerated, and the impurity concentration is low. Insufficient generation of insoluble matter tends to delay the progress of etching. Therefore, the diameter of the formed lens is affected by the impurity concentration of the substrate 1. Therefore, the concentration of impurities such as aluminum oxide contained in the substrate 1 should be constant within the substrate and between the substrates.
[0135]
Next, in order to examine the dependency of the etchant 4 on the temperature, the etching was performed while changing the temperature of the hydrofluoric acid aqueous solution, and the result will be described.
[0136]
Table 4 summarizes the results of examining the etching time by changing the etchant temperature while fixing the hydrofluoric acid concentration in the etchant to 10%. Note that this etching time means the time until the progress of etching is stopped as in Table 3 above.
[0137]
[Table 4]

[0138]
From the results shown in Table 4, the higher the etchant temperature, the shorter the time required for the etching to stop. Further, when the lens shapes obtained under the respective etching conditions were observed, it was found that similar shapes were obtained under any conditions. This means that the present invention does not greatly depend on the temperature of the etchant, and strict temperature control is unnecessary. Further, as in the case where the concentration is changed, strict time management is unnecessary, and it is possible to prevent insufficient etching and over-etching.
[0139]
Next, the results of study on the etching mask will be described below.
[0140]
As for the material of the etching mask, it is preferable that the etchant 4 hardly changes in quality and the adhesiveness with the substrate 1 is high. This is because when the adhesion is low, etching proceeds from the interface between the substrate 1 and the etching mask, which causes etching unevenness. The metal film 2 such as a chromium layer as in the present embodiment hardly changes in quality with respect to the hydrofluoric acid etching solution and has good adhesion to the substrate 1.
[0141]
Next, the result of examining the thickness of the chromium layer used for the metal film 2 of the etching mask will be described below.
[0142]
Table 5 summarizes the etching results when the thickness of the chromium layer is changed between 10 nm and 500 nm.
[0143]
[Table 5]

[0144]
As shown in Table 5, the chromium layer cannot be used as a mask when the thickness of the chromium layer is 10 nm or less and when the thickness is 500 nm or more. The reason is as follows.
[0145]
When the thickness of the chromium layer is 10 nm or less, pinholes are generated in the chromium layer, and the function as an etching mask cannot be fully exhibited, so that the etching mask is peeled off and a good etching state is obtained. I could not. In addition, when the thickness of the chromium layer is 500 nm or more, a large number of cracks are generated, and peeling that is considered to be caused by the stress of the chromium layer occurs with the progress of etching, so that a good etching state can be obtained. could not. For this reason, the thickness of the chromium layer in the present invention is preferably set in the range of 20 nm to 300 nm. Silicon, titanium, silver, platinum, gold, or the like can be used instead of chromium. However, since the same phenomenon as in the case of chromium occurs, it is preferably used within the above thickness range.
[0146]
Next, the result of examining the thickness of the resist 3 of the etching mask will be described below.
[0147]
Table 6 summarizes the etching results when the thickness of the resist 3 is changed between 100 nm and 6000 nm.
[0148]
[Table 6]

[0149]
As shown in Table 6, when the thickness of the resist 3 is 100 nm or less and when the thickness is 6000 nm or more, the resist 3 cannot be used as a mask for the following reason.
[0150]
When the thickness of the resist 3 was 100 nm or less, peeling of the etching mask occurred with the progress of etching, and a good etching state could not be obtained. Further, even when the thickness of the resist 3 was 6000 nm or more, the etching mask peeled off with the progress of etching, and a good etching state could not be obtained. For this reason, the thickness of the resist 3 in the present invention is preferably set in the range of 200 nm to 4000 nm.
[0151]
Note that this embodiment can be similarly applied not only to the formation of a microlens array but also to the formation of a single microlens.
[0152]
In the present embodiment, as described above, the etching proceeds automatically even if the substrate 1 is immersed in the etchant 4 after the etching is stopped due to the effect that the etching of the substrate 1 is automatically stopped by generating the insoluble matter 5. do not do. Therefore, it is possible to secure a large margin for the time for removing the substrate 1 from the etchant 4 after the etching is stopped.
[0153]
Further, even when a plurality of substrates 1 are processed at a time, the generation of the insoluble matter 5 is uniform between the substrates, so that uniform processing can be performed between the substrates. Further, even when a single substrate 1 is processed by a plurality of etching processes, the generation of the insoluble matter 5 is uniform between the etching processes, so that uniform processing can be performed between the etching processes. Therefore, even if the substrate 1 is enlarged and an in-plane distribution is generated in the etchant concentration or etching time, a uniform lens pattern can be produced not only in the substrate surface but also between the substrates, and the recesses in the substrate surface and between the substrates. The yield is improved by the uniformity of the shape, and the cost can be reduced by wet etching.
[0154]
In addition, since the generated insoluble matter 5 serves as a support for the etching mask, it is possible to prevent the etching mask composed of the metal film 2 and the resist 3 from being peeled off, thereby enabling more uniform processing. Become. Furthermore, glass for liquid crystal display such as alkali-free glass, low alkali glass, borosilicate glass, and lead glass is cheaper than quartz glass substrates and silicon wafer substrates. In this embodiment, these glass for liquid crystal display elements are used. Therefore, the cost can be reduced.
[0155]
The case where the microlens array substrate 12 according to the present embodiment is applied to a liquid crystal display element will be described.
[0156]
FIG. 2 is a perspective view schematically showing the appearance of the liquid crystal display element.
[0157]
As shown in the figure, the liquid crystal display element has a configuration in which a liquid crystal layer 52 is sandwiched between an adjustment glass plate 51 provided on a microlens array substrate 12 and a TFT substrate 50 manufactured by a known method. .
[0158]
In the liquid crystal display device having the above configuration, the light irradiated from the lower side of the figure is configured to be condensed at the transmission portion of the TFT substrate 50 by the microlens provided on the microlens array substrate 12, so that the light is The brightness of the portion where the liquid crystal molecules are arranged so as to transmit is increased. Further, by using the microlens array substrate 12 of the present embodiment, the luminance within the display surface becomes uniform.
[0159]
A method for manufacturing the liquid crystal display element will be described.
[0160]
3 to 5 are cross-sectional views illustrating a method for manufacturing a liquid crystal display element in the order of manufacturing steps.
[0161]
As shown in FIG. 3A, a metal film 202 and a resist 203 are sequentially formed on a non-alkali glass substrate 201, and an opening 203a is formed in the resist 203 and the metal film 202 by a known lithography process and etching process. . When forming the opening 203a, an exposure position adjustment marker 203b described below is formed. In FIG. 1, the exposure position adjustment marker 203b is not shown in the figure.
[0162]
As many exposure position adjustment markers 203b as necessary are provided at predetermined locations on the substrate 201. The exposure position adjustment marker 203b is relative to a reticle, a TFT substrate, or the like, which is a mask for a stepper exposure machine, during the first exposure for forming the opening 203a by the stepper exposure machine and the subsequent exposure. Is an alignment means used for accurate positioning, and generally has an accuracy of 1 μm or less. Although the number of steps increases, the opening 203a may be formed after the exposure position adjustment marker 203b is formed.
[0163]
Subsequently, as shown in FIG. 3B, before the substrate 201 is immersed in the etchant, a protective material 253 for protecting the exposure position adjustment marker 203b from the etchant is formed. The protective material 253 may be any material having resistance to an etchant, and a protective tape, an epoxy resin material, or the like can be suitably used as the protective material 253.
[0164]
Then, as shown in FIG. 3C, the substrate 201 is immersed in an etchant and the substrate 201 is etched. At this time, the protective material 253 prevents the shape change or peeling of the exposure position adjustment marker 203b. Further, since the columnar pattern 201a is provided around the concave portion to be a lens, the resist 203 and the metal film 202 are prevented from being peeled off.
[0165]
Thereafter, as shown in FIG. 3D, the protective material 253 is peeled off, and the resist 203 and the metal film 202 other than the exposure position adjustment marker 203b are peeled off. Here, the protective material 253 is peeled off. However, when the stepper exposure is performed by the subsequent stepper exposure machine, it does not need to be peeled off unless there is a problem.
[0166]
Subsequently, as shown in FIG. 3E, a high refractive index adhesive 254 is applied to the concave surface of the microlens array substrate 212, and a transparent adjustment glass plate 251 is bonded. At this time, the focal length of the lenses of the microlens array is adjusted, and the thickness of the adjustment glass plate 251 is adjusted so that the effect as a lens is maximized. After the adjustment glass plate 251 is bonded to the microlens array substrate 212, the adjustment glass 251 may be thinned to adjust the thickness. However, the adjustment glass plate 251 whose thickness has been adjusted in advance may be used as the microlens array substrate 212. You may paste. When thinning after bonding, an etching method or a mechanical polishing method can be suitably used. As described above, the glass plate 251 for adjustment as a transparent substrate is bonded to the recess forming surface side, so that the shape of the high refractive index adhesive 254 embedded in the recess is maintained, and the light refracted in the recess is the lath plate for adjustment. 251 can be transmitted.
[0167]
Thereafter, a thin film such as chromium or aluminum is formed on the adjustment glass plate 251 and a resist is applied thereon. Then, the reticle and the microlens array substrate 212 are positioned using the marker provided on the reticle for forming the pattern of the overlay position adjustment marker 255 and the pixel light shielding unit 256 and the exposure position adjustment marker 203b, and the stepper is positioned. Perform exposure and development. Subsequently, the overlay position adjustment marker 255 and the pixel light shielding portion 256 are formed by patterning that forms a pattern that matches the shape of the resist mask by etching (FIG. 3F).
[0168]
Thus, the exposure position adjustment marker 203b is used to position the reticle and the microlens array substrate 212 during stepper exposure. Therefore, the overlapping position adjustment marker 255 and the pixel light shielding unit 256 can be more accurately arranged at desired positions. The overlay position adjustment marker 255 is used to overlay the TFT substrate used for manufacturing the liquid crystal display element with high accuracy. Since overlaying with the TFT substrate can be performed with high accuracy, the overlay margin of the pixel light shielding portion 256 and the like can be made smaller, the aperture ratio becomes higher, and a liquid crystal display element capable of brighter display can be manufactured. Note that the pixel light shielding portion 256 is a light shielding means for preventing light from being applied to the TFT or the like.
[0169]
Thereafter, a transparent electrode, an alignment film, and the like not shown in the figure are formed on the adjustment glass plate 251 by a known method.
[0170]
Instead of bonding using the high refractive index adhesive, a high refractive index material is embedded in the formed recess, and an adhesive having substantially the same refractive index as that of the adjusting glass plate 251 is used to form a microlens array substrate. 212 and the glass plate 251 for adjustment may be bonded. Moreover, it is possible to adjust the focal length of the lenses of the microlens array by adjusting the refractive indexes of the high refractive index adhesive and the high refractive index material.
[0171]
Next, a method for overlaying the TFT substrate and the microlens array substrate will be described. There are two main methods of superposition. The first method is a method in which the TFT substrate and the microlens array substrate are overlapped and then cut into individual pieces, and the second method is to cut the TFT substrate and the microlens array substrate into pieces and then overlap them. Is the method.
[0172]
First, the first superposition method will be described.
[0173]
FIG. 4 is a schematic cross-sectional view showing the first superposition method.
[0174]
A microlens array substrate 212 shown in FIG. 3F is prepared (FIG. 4A). Subsequently, as shown in FIG. 4B, the TFT substrate 250 and the microlens array substrate 212 manufactured by a known method are used by using the overlay position adjustment marker 255 and the TFT substrate side overlay position adjustment marker 257. The positions are aligned and bonded with a sealant 258. At this time, a gap is provided between the TFT substrate 250 and the microlens array substrate 212 for liquid crystal. When the exposure position adjustment marker 203b is formed, an overlay position adjustment marker may be formed on the surface of the microlens array substrate 212, and this overlay position adjustment marker may be used when overlaying the TFT substrate 250. .
[0175]
Subsequently, as shown in FIG. 4C, the bonded TFT substrate 250 and the microlens array substrate 212 are separated into individual pieces by a cutting method in which high-pressure water is applied to the cut portions, and the two bonded pieces are combined. Liquid crystal is sealed between the plates to form a liquid crystal layer 252 to obtain a liquid crystal display element 260. According to this cutting method, even a structure in which the microlens array substrate 212 and the adjustment glass plate 251 are bonded with the high refractive index adhesive 254 can be efficiently cut. Note that the liquid crystal layer 252 may be sealed when the TFT substrate 250 and the microlens substrate 212 are bonded together.
[0176]
Next, the second overlapping method will be described.
[0177]
FIG. 5 is a schematic cross-sectional view showing a second superposition method.
[0178]
As shown in FIG. 5A, the microlens array substrate 212 is cut into individual pieces. A superposition position adjustment marker 255 is also formed on the microlens array substrate 212a that has been made into individual pieces. Subsequently, as shown in FIG. 5B, the TFT substrate 250a made into individual pieces and the microlens array substrate 212a made into individual pieces are used by using the superposition position adjustment marker 255 and the TFT substrate side superposition position adjustment marker 257. Then, the positions are aligned and bonded with a sealant 258. A liquid crystal layer 252 is formed by sealing liquid crystal between the two bonded plates, and the liquid crystal display element 260 is obtained.
[0179]
In FIGS. 4 and 5, the adjustment glass substrate 251 is bonded to the recess forming surface side of the microlens array substrate 212, and the liquid crystal layer 252 is formed between the adjustment glass substrate 251 and the TFT substrate 250. As described above, a liquid crystal layer 252 may be formed between the microlens array substrate 212 and the TFT substrate 250.
[0180]
FIG. 6 is a cross-sectional view showing another configuration example of the liquid crystal display element.
[0181]
The upside down direction of the individual microlens array substrate 212a shown in FIG. 5 is reversed so that the lens of the individual microlens array substrate 212a shown in FIG. ing. In the case of forming the structure shown in FIG. 6, the thickness of the microlens array substrate 212a is adjusted so as to maximize the lens effect. The thickness of the microlens array substrate 212 may be adjusted after the adjustment glass 251 is bonded to the concave surface of the microlens array substrate 212. However, the adjustment is made after the thickness of the microlens array substrate 212 is adjusted in advance. The glass plate 251 for use may be bonded. When thinning after bonding, an etching method or a mechanical polishing method can be suitably used.
[0182]
It is preferable that the TFT substrate of the liquid crystal display element and the microlens array substrate have relatively close linear thermal expansion coefficients, which are thermal expansion coefficients per unit length. When these two substrates having different linear thermal expansion coefficients are used, there is a problem in that reliability decreases due to peeling of the substrate in a heat cycle and misalignment due to thermal expansion. As the TFT substrate, an alkali-free glass or quartz substrate is often used. At this time, by using non-alkali glass or β-quartz transparent crystallized glass for the microlens array substrate according to the type of substrate of the TFT substrate, the linear thermal expansion coefficient between the TFT substrate and the microlens array substrate can be reduced. It becomes equal, the occurrence of the above problem is suppressed, and the reliability is further improved.
[0183]
Next, a case where the manufactured liquid crystal display element is applied as a liquid crystal light valve of a liquid crystal projector will be described.
[0184]
FIG. 7 is a schematic diagram showing a configuration example of a liquid crystal projector.
[0185]
As shown in the figure, the liquid crystal projector includes a light source 130, a polarization conversion integrator 132 that aligns the polarization direction of the light from the light source 130 and uniforms the light intensity, and white light from the light source 130 by dichroic mirrors 133 and 134. A color separation optical system that separates light beams of three colors of red, green, and blue, total reflection mirrors 135 to 137 for changing the traveling direction of the separated light beams, and the light beams of the three colors are irradiated 3 by color. A color synthesizing optical system composed of a plurality of liquid crystal display elements 138 to 140 and a cross dichroic prism 141 for synthesizing images displayed by the three liquid crystal display elements 138 to 140, and the synthesized display image on the screen. And a projection lens 142 for enlarging and projecting.
[0186]
The liquid crystal display elements 138 to 140 are an active matrix type in which thin film transistors (TFTs) are arranged for each pixel to drive liquid crystals. Further, a polarizing plate (not shown) whose polarization direction is orthogonal to the polarization direction of the polarization conversion integrator 132 is provided on the surface of each of the liquid crystal display elements 138 to 140 on the cross dichroic prism 141 side.
[0187]
Next, the operation of the liquid crystal projector having the above configuration will be described.
[0188]
As shown in the figure, the liquid crystal projector condenses the light emitted from the light source 130 by the reflector 131, separates the red light beam from the light beam by the dichroic mirror 133, and separates the green light beam by the dichroic mirror 134. Then, the light beams are separated into light beams of three colors of red, green and blue. The red light beam is reflected by the total reflection mirror 135 and then illuminates the red liquid crystal display element 138. The green light beam illuminates the green liquid crystal display element 139, and the blue light beam is sequentially reflected by the total reflection mirrors 136 and 137 and then illuminates the blue liquid crystal display element 140. The images displayed on the red, green, and blue liquid crystal display elements 138 to 140 are combined by the cross dichroic prism 141 and then enlarged and projected onto a screen (not shown) by the projection lens 142.
[0189]
The liquid crystal projector having the above configuration collects the light incident on the microlens at the aperture of the pixel, so that the brightness is improved and the projected image on the screen becomes brighter, and the microlens array substrate 12 of the present invention is used. As a result, the overall brightness of the projected image becomes uniform.
[0190]
Next, a case where the liquid crystal display element is applied to a liquid crystal display device will be described.
[0191]
FIG. 8 is a perspective view schematically showing the appearance of a transflective liquid crystal display device.
[0192]
As shown in the figure, the liquid crystal display device includes a liquid crystal display element 151, polarizing plates 152 and 153, a backlight unit 154 serving as a light source, and a signal supply circuit for sending a signal to a TFT provided for each pixel. 155, and a power supply unit 156 that supplies power to the backlight unit 154 and the signal supply circuit 155.
[0193]
The backlight unit 154 is provided with lamps of the three primary colors consisting of red, green and blue, and the screen of the liquid crystal display device can be displayed in color by controlling the switching of the lighting of the three primary colors at high speed. Instead of providing the three primary color lamps at 154, a color filter may be provided at the liquid crystal display element 151.
[0194]
In the liquid crystal display device having the above configuration, the display becomes brighter because the microlens array increases the light utilization rate of the backlight, and the brightness in the display screen becomes uniform by using the microlens array substrate 12 of the present invention.
[0195]
The liquid crystal display element according to the present embodiment can be used in, for example, a transflective liquid crystal display device disclosed in Japanese Patent Laid-Open No. 2000-298267.
[0196]
In addition, the liquid crystal display element manufactured according to the present embodiment is not limited to the above-described transflective liquid crystal display device, but a fine transmission type having a higher light blocking ratio than the transflective type and a fine reflection type having a lower light blocking ratio than the transflective type It can also be applied to liquid crystal display devices.
[0197]
(Second Embodiment)
In the second embodiment, the microlens array substrate 12 manufactured according to the first embodiment is used as a matrix for manufacturing a microlens array by a 2P molding method.
[0198]
FIG. 9 is a cross-sectional view showing the second embodiment of the present invention in the order of manufacturing steps.
[0199]
First, as shown in FIG. 9 (A), a release agent 7 and an ultraviolet curable resin as a resin 8 are sequentially applied to the concave portion forming surface of the mother die 6 and the surface to which the resin 8 is applied is directed downward. .
[0200]
Next, using alkali-free glass as the substrate 30, the surface of the substrate 30 and the surface of the resin 8 are aligned, and the mother die 6 is pressed against the substrate 30 side (FIG. 9B). After the resin 8 is irradiated with ultraviolet rays and cured, the mother die 6 is peeled off to form the convex resin 8 on the substrate 30, and the microlens array 32 composed of the resin 8 and the substrate 30. Is obtained (FIG. 9C).
[0201]
Note that after the step shown in FIG. 9C, anisotropic etching may be performed on the entire surface of the resin 8 to transfer the convex shape of the resin 8 to the substrate 30.
[0202]
The resin 8 is preferably a photo-curing resin that is cured by light irradiation, a thermosetting resin that is cured by heating, or a two-component adhesive. As the material of the mother die 6, it is preferable to use the same material as the substrate 30 or a material having a thermal expansion coefficient close to that of the substrate 30.
[0203]
In the present embodiment, since the microlens array substrate 12 of the first embodiment has a uniform concave shape in a large area, by using the microlens array substrate 12 for the mother die 6, a large mother The mold can be manufactured at a high yield and at a low cost.
[0204]
Further, by using the same material or a material having a similar thermal expansion coefficient for the mother die 6 and the substrate 30, compared to a case where a material different from the substrate 30 such as a metal or a quartz glass substrate is used as the material of the mother die 6. The error due to the difference in thermal expansion coefficient can be reduced, and strict temperature management is not required. Moreover, the error which arises in a heating process at the time of using a thermosetting resin can be made small.
[0205]
Furthermore, since inexpensive alkali-free glass or the like can be used as the material of the mother die 6 and the substrate 30, the cost can be reduced. In addition, since the microlens array 32 can be molded using the large matrix 6, it is not necessary to press the mold many times with high accuracy using the small matrix, which is advantageous in terms of cost.
[0206]
In addition, when using the microlens array 32 produced by this embodiment as a microlens array for light valves of a liquid crystal projector, the following processes are added.
[0207]
First, an adhesive having a lower refractive index than that of the resin 8 or the substrate 30 is applied to the convex molding surface of the microlens array 32 and glass is bonded. Next, after adjusting the thickness of the glass so that the focal point of the lens formed on the convex portion of the microlens array 32 is aligned with the transmission portion of the TFT substrate manufactured by a known method, the TFT substrate is moved to the microlens array. 12 to obtain a light valve microlens array.
[0208]
After that, by forming transparent electrodes for wiring and markers for alignment on the microlens array for light valves, and performing a known panel manufacturing process, a light valve with a microlens array for liquid crystal projectors is formed. obtain.
[0209]
In order to apply the microlens array 32 manufactured according to the present embodiment to a liquid crystal display element with a microlens array, the following steps may be performed. An application example of the liquid crystal display element with a microlens array is a transflective liquid crystal display element.
[0210]
First, a resin 8 was applied to the surface of a light incident side substrate of a liquid crystal display element manufactured by a known method using a substrate having an appropriate thickness, and the mold 8 was embossed on the resin 8. Thereafter, the resin 8 is cured to obtain the microlens array 32. Next, alignment is performed so that the backlight light transmitted through the lenses of the microlens array 32 is condensed on the transmission portion of the pixel electrode of the TFT substrate, and the light incident side substrate is assembled to the TFT substrate, whereby the microlens is assembled. A liquid crystal display element with an array is obtained. Thereby, the liquid crystal display element with a microlens array with a uniform lens pattern can be produced at lower cost.
[0211]
(Third embodiment)
In the third embodiment, the present invention is applied to the production of an optical waveguide by an isotropic etching method.
[0212]
FIG. 10 is a cross-sectional view showing a third embodiment of the present invention in the order of manufacturing steps.
[0213]
As shown in FIG. 10A, as in the first embodiment, a non-alkali glass that uniformly contains aluminum oxide or the like is used as the substrate 1, and the metal film 2 and the resist 3 are formed on the substrate 1. An etching mask is formed.
[0214]
In addition, although the rectangular opening 3b that follows the pattern of the optical waveguide is formed in the etching mask, the width of the two opposite sides of the opening 3b is as shown in Table 1 in the first embodiment. A table showing the relationship between the width of the opening 3b and the width of the optical waveguide to be formed is created in advance, and is determined from the width of the optical waveguide formed based on the created table.
[0215]
Next, the substrate 1 is etched using a hydrofluoric acid-based etchant as the etchant 4. FIG. 10B is a cross-sectional view showing an initial stage state of etching.
[0216]
When etching starts, isotropic etching of the substrate 1 proceeds from the opening 3b, and a minute groove is formed. Aluminum fluoride or the like, which is an insoluble matter 5 with respect to the etchant, accumulates on the surface of the substrate in the minute groove portion, and the progress of the etching of the substrate 1 is hindered. A waveguide pattern is formed (FIG. 10C).
[0217]
After removing the insoluble matter 5 together with the metal film 2 and the resist 3, a high refractive index material having a higher refractive index than that of the substrate 1 is embedded in the formed groove portion to form the optical waveguide 13 (FIG. 10D). .
[0218]
In this embodiment, aluminum oxide or the like is included in the substrate 1 as a substance that generates the insoluble material 5 with respect to the etchant 4, and the insoluble material 5 with respect to the etchant 4 is generated by etching. Thus, a uniform optical waveguide pattern can be produced at low cost even on a large-area substrate without providing an etching stopper layer or the like. Moreover, there is no variation in the etching amount in each etching process, and an optical waveguide pattern having a uniform recess shape between etching processes can be formed.
[0219]
Further, as described in the first embodiment, if the substrate 1 is oxyhalide glass, calcium fluoride or the like is contained as a substance that does not dissolve in the hydrofluoric acid-based etching solution. The same action and effect as the product 5 are produced.
[0220]
In addition, after removing the insoluble matter 5 together with the metal film 2 and the resist 3, a high refractive index material was molded on another substrate by using the 2P molding method with the fabricated optical waveguide-shaped depression pattern as a matrix. It is also possible to obtain a strip waveguide or a rib waveguide by forming an optical waveguide. In this case as well, it is possible to manufacture a large matrix at a high yield and low cost, to reduce errors due to differences in thermal expansion coefficients, and to eliminate the need for strict temperature control. It is possible to reduce the error in the heating process at the time of use, and to obtain an effect that the cost can be reduced because inexpensive alkali-free glass or the like can be used as a matrix material.
[0221]
(Fourth embodiment)
In the fourth embodiment, the present invention is applied to the fabrication of a buried wiring by an isotropic etching method.
[0222]
FIG. 11 is a cross-sectional view showing a fourth embodiment of the present invention in the order of manufacturing steps.
[0223]
As shown in FIG. 11A, as in the first embodiment, a non-alkali glass containing aluminum oxide or the like is uniformly used as the substrate 1 and the metal film 2 and the resist 3 are formed on the substrate 1. An etching mask is formed.
[0224]
Note that a rectangular opening 3c that follows the pattern of the embedded wiring is formed in the etching mask. The widths of two opposite sides of the opening 3c are as shown in Table 1 in the first embodiment. A table showing the relationship between the width of the opening 3c and the width of the embedded wiring to be formed is prepared in advance, and is determined from the width of the embedded wiring formed based on the generated table.
[0225]
Next, the substrate 1 is etched using a hydrofluoric acid-based etchant as the etchant 4. FIG. 11B is a cross-sectional view showing the state of the initial stage of etching.
[0226]
When etching starts, isotropic etching of the substrate 1 proceeds from the opening 3c, and a minute groove is formed. Aluminum fluoride or the like, which is an insoluble matter 5 with respect to the etchant, accumulates on the surface of the substrate in the minute groove portion, and the progress of the etching of the substrate 1 is hindered. A pattern is formed (FIG. 11C).
[0227]
After removing the insoluble matter 5 together with the metal film 2 and the resist 3, a wiring metal layer 9 is formed by using a known method such as sputtering (FIG. 11D). Next, using a chemical or mechanical polishing method, the wiring metal layer 9 other than in the formed groove is removed to form a buried wiring 9a (FIG. 11E).
[0228]
In this embodiment, aluminum oxide or the like is included in the substrate 1 as a substance that generates the insoluble material 5 with respect to the etchant 4, and the insoluble material 5 with respect to the etchant 4 is generated by etching. Therefore, even for a large-area substrate, a uniform embedded wiring pattern can be manufactured at low cost. Moreover, there is no variation in the etching amount in each etching process, and a buried wiring pattern having a uniform recess shape between the etching processes can be formed.
[0229]
Further, as described in the first embodiment, if the substrate 1 is oxyhalide glass, calcium fluoride or the like is contained as a substance that does not dissolve in the hydrofluoric acid-based etching solution. The same action and effect as the product 5 are produced.
[0230]
(Fifth embodiment)
In the fifth embodiment, the present invention is applied to the production of a diffraction grating by an isotropic etching method.
[0231]
FIG. 12 is a cross-sectional view showing a fifth embodiment of the present invention in the order of manufacturing steps.
[0232]
As shown in FIG. 12 (A), a resist 3 is applied on a non-alkali glass substrate 1 containing aluminum oxide or the like uniformly using a known technique such as spin coating and dried. As the resist 3, a resist that corresponds to the wavelength of light used in the exposure of the next step and has a resolution that can form a diffraction grating is used. As an example, an excimer laser photoresist can be preferably used.
[0233]
Thereafter, the resist 3 is subjected to interference exposure using an excimer laser beam or the like, and an etching mask having a diffraction grating pattern composed of fine openings 3d is formed through a resist development process (FIG. 12B). ).
[0234]
A rectangular opening 3d that follows the pattern of the diffraction grating is formed in the etching mask. The width of the two opposite sides of the opening 3d and the interval between the openings 3d are shown in the first embodiment. As shown in Table 1, a table showing the relationship between the width and interval of the opening 3d and the width of the concave portion of the diffraction grating formed in advance is prepared, and the width of the concave portion of the diffraction grating formed based on the prepared table Determine from.
[0235]
Next, the substrate 1 is etched using a hydrofluoric acid-based etchant as the etchant 4. FIG. 12C is a cross-sectional view showing an initial stage state of etching.
[0236]
When the etching starts, isotropic etching of the substrate 1 proceeds from the opening 3d, and a minute groove is formed. On the surface of the substrate 1 in the minute groove portion, aluminum fluoride or the like, which is an insoluble material 5 with respect to the etchant 4 is accumulated due to the etching, and the progress of the etching of the substrate 1 is inhibited, and the etching is finally stopped. To do.
[0237]
Thereafter, when the resist 3 is peeled off and the insoluble matter 5 is washed away, as shown in FIG. 12D, a diffraction grating 34 provided with a plurality of grooves is formed.
[0238]
In this embodiment, the substrate 1 contains aluminum oxide or the like as a substance that generates the insoluble matter 5 with respect to the etchant 4, and the insoluble matter 5 with respect to the etchant 4 is generated by etching. Thus, a uniform diffraction grating pattern can be produced at low cost even on a large-area substrate. Moreover, there is no variation in the etching amount in each etching process, and a diffraction grating having a uniform pattern shape between etching processes can be formed.
[0239]
The substrate 1 may be low alkali glass, borosilicate glass, or lead glass in addition to the alkali-free glass as in the first embodiment. If the substrate 1 is oxyhalide glass, calcium fluoride or the like is contained as a substance that does not dissolve in the hydrofluoric acid-based etching solution, so that calcium fluoride or the like produces the same actions and effects as the insoluble matter 5.
[0240]
Further, the diffraction grating 34 manufactured in this way can be used as a large-area and inexpensive optical element. For example, by using it as a substrate of an organic electroluminescence element, the light extraction efficiency can be improved. You can also. In this case, the advantage that a large-area diffraction grating 34 can be manufactured by an inexpensive method using an inexpensive alkali-free glass substrate can be utilized to the maximum.
[0241]
(Sixth embodiment)
In the sixth embodiment, the present invention is applied to the production of a liquid crystal alignment film by an isotropic etching method.
[0242]
FIG. 13 is a cross-sectional view showing a sixth embodiment of the present invention in the order of manufacturing steps.
[0243]
As shown in FIG. 13A, a transparent electrode 10 is formed on a substrate 1, and an alignment film 11 for determining the alignment direction of liquid crystal molecules is formed on the transparent electrode 10. The alignment film 11 is an inorganic material film containing aluminum oxide or the like uniformly.
[0244]
Next, as shown in FIG. 13B, an etching mask is formed using the same method as in the fifth embodiment, but the longitudinal direction of the rectangular opening 3e is injected in the alignment direction of the liquid crystal molecules. Keep almost the same. As a material for the etching mask, a resist 3 or the like can be preferably used.
[0245]
A rectangular opening 3e following the pattern of the liquid crystal alignment film to be formed is formed on the etching mask. The width of the two opposite sides of the opening 3e and the interval between the openings 3e are the same as those in the first embodiment. As shown in Table 1, a table showing the relationship between the width and interval of the opening 3e and the width of the recess of the liquid crystal alignment film to be formed is created in advance, and the liquid crystal formed based on the created table It is determined from the width of the concave portion of the alignment film.
[0246]
Thereafter, the alignment film 11 is etched using a hydrofluoric acid-based etchant as the etchant 4. FIG. 13C is a cross-sectional view showing an initial stage state of etching.
[0247]
When the etching starts, isotropic etching of the alignment film 11 proceeds, and a minute groove is formed. On the surface of the alignment film in the minute groove, aluminum fluoride or the like, which is an insoluble matter 5 with respect to the etchant 4, is generated by etching, and the progress of the etching of the alignment film 11 is hindered, and finally the etching stops. To do.
[0248]
Next, when the resist 3 is peeled off and the insoluble material 5 is washed away, as shown in FIG. 13D, a liquid crystal alignment film 11a in which a plurality of grooves and linear protrusions are alternately provided is formed.
[0249]
In this embodiment, the alignment film 11 includes aluminum oxide or the like as a substance that generates the insoluble matter 5 with respect to the etchant 4, and the insoluble matter 5 with respect to the etchant 4 is generated by etching. Even when it is automatically stopped and manufactured on a large-area substrate, a liquid crystal alignment film having a uniform uneven shape can be manufactured at low cost. Moreover, there is no variation in the etching amount in each etching process, and a liquid crystal alignment film having a uniform pattern shape between etching processes can be formed.
[0250]
Further, instead of containing aluminum oxide or the like that generates the insoluble matter 5, at least one of the substances such as calcium fluoride described in the first embodiment is contained in the alignment film 11 as a substance that does not dissolve in the etchant 4. It may be. When the alignment film 11 contains a substance that does not dissolve in the etchant 4, this substance causes the same action and effect as the insoluble matter 5.
[0251]
Further, using two substrates 1 on which the liquid crystal alignment film 11 is formed, a sealing material is printed on one of them, and then the two substrates 1 are bonded to form a panel, and liquid crystal is injected into the panel. A liquid crystal display element was obtained. As a result, a highly reliable and uniform liquid crystal alignment film can be manufactured over a large area at low cost.
[0252]
In particular, by using an inorganic material as the alignment film 11, when used in combination with a partition structure for partitioning a space into which liquid crystal is injected, damage to the alignment film due to the partition manufacturing process can be eliminated. Uniform orientation can be obtained even when smectic liquid crystals that are susceptible to damage are used.
[0253]
(Seventh embodiment)
In the seventh embodiment, the present invention is applied to the production of a wire grid type polarization optical element.
[0254]
FIG. 14 is a cross-sectional view showing a seventh embodiment of the present invention in the order of manufacturing steps.
[0255]
As shown in FIG. 14A, a metal film 20 is formed over the substrate 1. In addition, as a material of the metal film 20, for example, an alloy of Ti and Al can be used, and the film is formed by using a known sputtering method or the like.
[0256]
Next, as shown in FIG. 14B, an etching mask is formed of the resist 3 using the same method as in the fifth embodiment, but the longitudinal direction of the rectangular opening 3f is the direction of polarization to be transmitted. And keep them orthogonal.
[0257]
A rectangular opening 3f that follows the pattern of the polarizing optical element to be formed is formed on the etching mask. The width of the two opposite sides of the opening 3f and the interval between the openings 3f are the same as those in the first embodiment. As shown in Table 1, a table showing the relationship between the width and interval of the opening 3f and the width of the concave portion of the polarizing optical element to be formed is created in advance, and polarization formed based on the created table It is determined from the width of the concave portion of the optical element.
[0258]
Thereafter, the metal film 20 is etched using the metal film etchant 40 containing hydrofluoric acid. FIG. 14C is a cross-sectional view showing an initial stage state of etching.
[0259]
When the etching starts, isotropic etching of the metal film 20 proceeds and a minute groove is formed. Aluminum fluoride, which is an insoluble material 5 with respect to the etchant 4 generated by the etching, accumulates on the surface of the metal film in the minute groove portion, and the progress of the etching of the metal film 20 is inhibited, and the etching is finally stopped.
[0260]
Thereafter, when the resist 3 is peeled off and the insoluble matter 5 is washed away, as shown in FIG. 14D, a wire grid type polarizing optical element 20a in which a plurality of grooves and metal wires are alternately provided is obtained.
[0261]
In the present embodiment, the metal film 20 contains aluminum, which is a substance that generates the insoluble matter 5 with respect to the etchant 4, and the insoluble matter 5 with respect to the etchant 4 is generated by the etching. Therefore, even when manufacturing on a large-area substrate, a wire grid type polarization optical element with a uniform metal line pattern can be manufactured at low cost. Moreover, there is no variation in the etching amount in each etching process, and a polarizing optical element having a uniform pattern shape between etching processes can be formed.
[0262]
Further, by using the condition that the side etching of the metal film 20 under the resist 3 stops when the etching from the opening 3f reaches the substrate 1, over-etching of the metal film 20 under the resist 3 can be prevented. it can.
[0263]
The metal film 20 may contain at least one of substances of magnesium, calcium, potassium, strontium, barium, lithium, sodium, cesium, zinc, and lead. These substances react with hydrofluoric acid to produce the insoluble matter 5 in the same manner as the aluminum.
[0264]
(Eighth embodiment)
The eighth embodiment is an embodiment in which the present invention is applied to microchip pattern fabrication used in microchemical analysis systems and LOC by isotropic etching.
[0265]
FIG. 15 is a top view showing the concave pattern of the microchip fabricated on the substrate surface.
[0266]
As shown in FIG. 15, on the surface of the microchip substrate 1, a reagent tank 15 into which chemicals are injected, a reaction tank 16 in which various chemicals are mixed and reacted, and a chemical from the reagent tank 15 to the reaction tank 16. And a microchip liquid outlet path 14 for moving the microchip.
[0267]
A method for producing the microchip liquid outlet 14 will be described below.
[0268]
FIG. 16 is a cross-sectional view showing an eighth embodiment of the present invention in the order of manufacturing steps. Note that the portion shown in FIG. 16 is a cross section of the broken line portion YY ′ shown in FIG.
[0269]
As shown in FIG. 16A, as in the first embodiment, a non-alkali glass containing aluminum oxide or the like is uniformly used as the substrate 1, and a liquid discharge path for microchip is provided on the substrate 1. An etching mask made of the metal film 2 and the resist 3 is formed.
[0270]
Note that a rectangular opening 3g that follows the pattern of the liquid discharge passage 14 for microchips is formed on the etching mask. The widths of the two opposite sides of the opening 3g are shown in Table 1 shown in the first embodiment. A table showing the relationship between the width of the opening 3g and the width of the microchip liquid outlet 14 formed in advance is prepared, and the pattern of the microchip liquid outlet 14 formed on the basis of the prepared table Determine from the width of.
[0271]
Next, the substrate 1 is etched using a hydrofluoric acid-based etchant as the etchant 4. FIG. 16B is a cross-sectional view showing an initial stage state of etching.
[0272]
When etching starts, isotropic etching of the substrate 1 proceeds from the opening 3g, and a minute groove is formed. On the surface of the substrate in the minute groove, aluminum fluoride or the like, which is an insoluble matter 5 with respect to the etchant, is accumulated, hindering the progress of the etching of the substrate 1, and finally the etching is stopped and the liquid is stopped. An exit pattern is formed (FIG. 16C).
[0273]
After removing the insoluble matter 5 together with the metal film 2 and the resist 3, a liquid discharge path 14 for microchip is obtained (FIG. 16D).
[0274]
In the reagent tank 15 and the reaction tank 16, a pattern is formed by accumulating the insoluble matter 5 in the reagent tank 15 and the reaction tank 16 by the above-described manufacturing method, as in the liquid discharge path 14 for microchip.
[0275]
When the pattern interval of the microchip liquid discharge path 14 is narrowed to increase the pattern integration degree, the width of the two opposite sides of the opening 3g and the interval between the openings 3g are the same as in the first embodiment. If a table showing the relationship between the width of the two opposite sides of the opening 3g and the interval between the openings 3g and the width of the microchip liquid discharge path 14 is created, and determined from the width of the formed microchip liquid discharge path 14 Good.
[0276]
Further, in the present embodiment, the pattern of the microchip liquid outlet 14 has been described as a method for producing the microchip pattern. However, the present embodiment can also be applied to the pattern of the reagent tank 15 and the reaction tank 16. it can. At that time, if the microchip pattern is a polygon including not only a quadrangle but also an octagon, the width of two opposite sides of the opening 3g is changed to the maximum width of the opening 3g, and the maximum of the opening 3g is obtained. A table showing the relationship between the size of the microchip pattern to be formed and the width of the microchip pattern may be prepared in advance, and the maximum width of the opening 3g may be determined from the width of the microchip pattern formed based on the generated table.
[0277]
In this embodiment, aluminum oxide or the like is included in the substrate 1 as a substance that generates the insoluble matter 5 with respect to the etchant 4, and the insoluble matter 5 with respect to the etchant 4 is generated by the etching. Thus, a uniform microchip pattern can be produced at low cost even on a large-area substrate. Further, there is no variation in the etching amount in each etching process, and a microchip pattern having a uniform recess shape between etching processes can be formed.
[0278]
Further, as described in the first embodiment, if the substrate 1 is oxyhalide glass, calcium fluoride or the like is contained as a substance that does not dissolve in the hydrofluoric acid-based etching solution. The same action and effect as the product 5 are produced.
[0279]
The present invention is not limited to the fine structure forming application in the first to eighth embodiments as described above, and even when a large structure is formed, the etching amount is controlled, It can be used for the purpose of improving the uniformity of the pattern shape to be formed. This is because even when a large structure is formed, insoluble matter with respect to the etchant accumulates on the surface of the object to be etched, and the progress of etching can be stopped.
[0280]
In addition to isotropic etching, even when etching has a certain degree of anisotropy, as described above, the etching is stopped by generating a substance insoluble in the etching solution, and the formed pattern has a uniform shape. It can be used for the purpose of improving the property.
[0281]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0282]
For the microstructure obtained by using the microstructure forming method using the isotropic etching method of the present invention, even when the present invention is used for etching a plurality of large substrates, not only within the substrate plane but also between the substrates. However, a highly uniform microstructure can be produced. Further, since a relatively inexpensive glass for a liquid crystal display element can be used, the cost can be reduced.
[0283]
Furthermore, by using the present invention for the fabrication of the mother mold in the 2P molding method, it becomes possible not only to produce a large mother mold at a high yield at a low cost, but also to use the same type of substrate as the mother mold. Therefore, the error due to the difference in thermal expansion coefficient can be reduced, and strict temperature control is not required. Since a large matrix can be used, the cost can be reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in the order of manufacturing steps.
FIG. 2 is a perspective view schematically showing the appearance of a liquid crystal display element using a microlens array substrate 12 manufactured according to the first embodiment.
FIG. 3 is a cross-sectional view showing a manufacturing method of a liquid crystal display element using the microlens array substrate manufactured according to the first embodiment in order of manufacturing steps.
FIG. 4 is a cross-sectional view showing a manufacturing method of a liquid crystal display element using the microlens array substrate manufactured according to the first embodiment in the order of manufacturing steps.
FIG. 5 is a cross-sectional view showing a manufacturing method of a liquid crystal display element using the microlens array substrate manufactured according to the first embodiment in the order of manufacturing steps.
FIG. 6 is a cross-sectional view showing another configuration example of the liquid crystal display element using the microlens array substrate manufactured according to the first embodiment.
7 is a schematic diagram showing a configuration example of a liquid crystal projector using the liquid crystal display element shown in FIG. 2. FIG.
8 is a perspective view schematically showing the appearance of a transflective liquid crystal display device using the liquid crystal display element shown in FIG.
FIG. 9 is a cross-sectional view showing a second embodiment of the present invention in the order of manufacturing steps.
FIG. 10 is a cross-sectional view showing a third embodiment of the present invention in the order of manufacturing steps.
FIG. 11 is a cross-sectional view showing a fourth embodiment of the present invention in the order of manufacturing steps.
FIG. 12 is a cross-sectional view showing a fifth embodiment of the present invention in the order of manufacturing steps.
FIG. 13 is a cross-sectional view showing a sixth embodiment of the present invention in the order of manufacturing steps.
FIG. 14 is a cross-sectional view showing a seventh embodiment of the present invention in the order of manufacturing steps;
FIG. 15 is a top view showing a recess pattern of a microchip manufactured according to an eighth embodiment of the present invention.
FIG. 16 is a cross-sectional view showing an eighth embodiment of the present invention in the order of manufacturing steps;
FIG. 17 is a cross-sectional view for explaining a manufacturing process of a microlens array using a conventional 2P molding method.
FIG. 18 is a cross-sectional view for explaining a manufacturing process of a microlens array using a conventional transfer method.
FIG. 19 is a cross-sectional view for explaining a manufacturing process of a microlens array using a conventional isotropic etching method.
[Explanation of symbols]
1, 30, 201 substrate
1a, 201a Columnar pattern
2, 20, 202 Metal film
3, 203 resist
3a, 3b, 3c, 3d, 3e, 3f, 3g, 203a Opening
4 Etchant
5 Insoluble matter
6,114 mother mold
7, 107 Mold release agent
8,108 Resin
9 Metal layer for wiring
9a Embedded wiring
10 Transparent electrode
11 Alignment film
11a Liquid crystal alignment film
12, 212 Micro lens array substrate
13 Optical waveguide
14 Liquid outlet for microchip
15 Reagent tank
16 Reaction tank
20a Polarizing optical element
32, 112, 120, 122 Microlens array
34 Diffraction grating
40 Metal film etchant
50, 250a TFT substrate
51,251 Adjustment glass plate
52, 252 Liquid crystal layer
100 glass substrate
104 Wet etchant
115 Thermally deformable pattern
115a hemispherical pattern
116 Mask layer
117 Quartz glass substrate
130 Light source
131 reflector
132 Polarization Conversion Integrator
133, 134 Dichroic mirror
135, 136, 137 Total reflection mirror
138 Liquid crystal display element for red
139 Green liquid crystal display element
140 Blue liquid crystal display element
141 Cross Dichroic Prism
142 Projection lens
151,260 Liquid crystal display element
152, 153 Polarizing plate
154 Backlight unit
155 signal supply circuit
156 Power supply unit
203b Exposure position adjustment marker
212a Microlens array substrate in pieces
250a piece TFT substrate
253 protective material
254 High refractive index adhesive
255 Overlay position adjustment marker
256 pixel shading part
257 TFT substrate side overlay position adjustment marker
258 Sealant

Claims (30)

This is a microstructure forming method in which an etching target is used to etch an object to be etched, which is provided with a mask having a predetermined opening on the surface, and the recess is formed on the surface of the object to be etched. And
Insoluble matter is generated by a reaction between the substance contained in the object to be etched and the etching solution,
Etching is stopped by insoluble matter accumulated on the exposed surface of the object to be etched. The fine structure forming method according to claim 1,
Fine material characterized in that the object to be etched contains at least one of aluminum oxide, magnesium oxide, calcium oxide, potassium oxide, strontium oxide, barium oxide, lithium oxide, sodium oxide, cesium oxide, zinc oxide, and lead oxide Structure formation method. This is a microstructure forming method in which an etching target is used to etch an object to be etched, which is provided with a mask having a predetermined opening on the surface, and the recess is formed on the surface of the object to be etched. And
Leaching the substance from the object to be etched containing a substance that does not dissolve in the etchant;
Etching is stopped by a substance that accumulates on the exposed surface of the object to be etched. In the fine structure formation method according to claim 3,
A method for forming a microstructure, wherein the object to be etched includes at least one of calcium fluoride, sodium fluoride, barium fluoride, aluminum fluoride, strontium fluoride, and magnesium fluoride. The fine structure forming method according to claim 2 or 4,
A method for forming a fine structure, characterized in that the etching solution contains hydrofluoric acid. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is a microlens. In the fine structure formation method according to any one of claims 1 to 6,
The opening provided in the mask is circular,
Create a table showing the relationship between the diameter of the opening and the diameter of the recess formed corresponding to the diameter of the opening,
According to the table, the diameter of the opening corresponding to a desired recess diameter is formed in a mask. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is used in a microlens array in which concave portions are continuously formed. The fine structure forming method according to claim 8,
The opening provided in the mask is circular,
Create a table showing the relationship between the diameter and spacing of the opening and the diameter of the recess formed corresponding to the diameter and spacing of the opening,
According to the table, the diameter and the interval of the opening corresponding to a desired recess diameter are formed in a mask. The fine structure forming method according to claim 9, wherein
A method for forming a fine structure, wherein the diameter of the opening is 1/3 or less of the interval between the openings. The fine structure forming method according to claim 9 or 10,
A fine structure forming method, wherein the diameter of the opening is 1/10 or more of the interval between the openings. The fine structure forming method according to claim 8,
The opening provided in the mask is square,
Create a table showing the relationship between the width of the two opposite sides of the opening and the interval between the openings, and the width of the recess formed corresponding to the width and interval of the openings,
A fine structure forming method, wherein a width and an interval of the opening corresponding to a desired recess width are formed in a mask according to the table. The method for forming a microstructure according to claim 12, wherein
A method for forming a microstructure, characterized in that the width of two opposite sides of the opening is 1/3 or less of the interval between the openings. In the fine structure formation method according to claim 12 or 13,
A method for forming a fine structure, wherein the width of two opposite sides of the opening is 1/10 or more of the interval between the openings. The method for forming a microstructure according to any one of claims 8 to 14,
The object to be etched is a glass substrate,
A method for forming a microstructure, characterized in that a mask is composed of a metal film and an organic film formed in order on the surface of the glass substrate. The fine structure forming method according to claim 15, wherein
A method for forming a fine structure, wherein the thickness of the metal film is 20 nm to 300 nm. The fine structure forming method according to claim 15 or 16,
A method for forming a fine structure, wherein the organic film has a thickness of 200 nm to 4000 nm. The method for forming a microstructure according to any one of claims 8 to 17,
An alignment means is provided on the surface of the object to be etched,
A fine structure forming method comprising forming a protective material for protecting the alignment means from an etching solution. The fine structure forming method according to claim 18,
A method for forming a fine structure, characterized in that the alignment means is manufactured in the same process as the mask having the opening. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is a pattern for an optical waveguide. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is an embedded wiring pattern. In the fine structure formation method according to any one of claims 1 to 6, claim 20, and claim 21,
The opening provided in the mask is square,
Create a table showing the relationship between the width of the two opposite sides of the opening and the width of the recess formed corresponding to the width of the opening,
A fine structure forming method, wherein a width of the opening corresponding to a desired recess width is formed using a mask according to the table. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is a diffraction grating. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is a liquid crystal alignment film. The fine structure forming method according to claim 1,
A fine structure forming method, wherein the fine structure is a polarizing optical element. The fine structure forming method according to claim 25,
A method for forming a microstructure, characterized in that the object to be etched contains at least one of aluminum, magnesium, calcium, potassium, strontium, barium, lithium, sodium, cesium, zinc, and lead. The method for forming a microstructure according to claim 26, wherein
A method for forming a fine structure, characterized in that the etching solution contains hydrofluoric acid. In the fine structure formation method according to any one of claims 1 to 5,
A fine structure forming method, wherein the fine structure is a pattern for a microchip. The microstructure forming method according to claim 28, wherein
The opening provided in the mask is polygonal,
Create a table showing the relationship between the maximum width of the opening and the width of the recess formed corresponding to the maximum width of the opening,
A fine structure forming method, wherein a maximum width of the opening corresponding to a desired recess width is formed using a mask according to the table. The fine structure forming method according to any one of claims 23 to 28,
The opening provided in the mask is square,
Create a table showing the relationship between the width of the two opposite sides of the opening and the interval between the openings, and the width of the recess formed corresponding to the width and interval of the openings,
A fine structure forming method, wherein a width and an interval of the opening corresponding to a desired recess width are formed in a mask according to the table.

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