JP4273679B2 - Split sequential proximity exposure system - Google Patents

Description

【００４４】
なお、この実施の形態では、基板Ｗとして、図８に示す１０００ｍｍ×１２００ｍｍの基板Ｗで１８インチディスプレイ用材ＤＰを９面取りするものと、図示は省略するが図８と同じ大きさの基板Ｗで１５インチディスプレイ用材ＤＰを１２面取り（ステップ方向４×幅方向３）するものを用いる。
図８に示す１８インチディスプレイ用材ＤＰを９面取りする基板Ｗに用いるマスクＭ及び該マスクＭのパターン領域の大きさとしては、図９（ａ）に示すように、基板Ｗの幅方向に３個のマスクパターンＰ（１８インチディスプレイ用材ＤＰに対応する）が描かれた１１００ｍｍ×７００ｍｍ（ステップ方向寸法ａ）のものや、図９（ｂ）に示すように、基板Ｗの幅方向に３個描かれたマスクパターンＰが基板Ｗのステップ方向に二列（合計６個）配置された１１００ｍｍ×９００ｍｍ（ステップ方向寸法ａ）ものが考えられ、前者では基板Ｗのステップ回数は３回（一回目の露光位置を１ステップとする。）となり、後者では基板Ｗのステップ回数は２回となる。
【００４５】
ここで、露光精度等の兼ね合いからたわみ最大値δｍａｘの許容値を６０μｍとすると、図１１及び表１から、ステップ方向寸法ａが９００ｍｍの図９（ｂ）のマスクＭは適用できず、ステップ方向寸法ａが７００ｍｍの図９（ａ）のマスクＭを選択することになる。
一方、１５インチディスプレイ用材ＤＰを１２面取りする基板Ｗに用いるマスクＭ及び該マスクＭのパターン領域の大きさとしては、図示は省略するが、基板Ｗの幅方向に３個のマスクパターンＰ（１５インチディスプレイ用材ＤＰに対応する）が描かれたのものや、図１０に示すように、基板Ｗの幅方向に３個描かれたマスクパターンＰが基板Ｗのステップ方向に二列（合計６個）配置された１１００ｍｍ×７００ｍｍ（ステップ方向寸法ａ）ものや、図示は省略するが、基板Ｗの幅方向に３個描かれたマスクパターンＰが基板Ｗのステップ方向に三列（合計９個）配置されたものが考えられ、前者では基板Ｗのステップ回数は４回（１回目の露光位置を１ステップとする。）、後者の２つでは基板Ｗのステップ回数は２回となる。
【００４６】
ここで、上記同様に露光精度等の兼ね合いからたわみ最大値δｍａｘの許容値を６０μｍとすると、図１１及び表１から、ステップ方向寸法ａが９００ｍｍを越える９個のマスクパターンＰが描かれたマスクＭは適用できず、ステップ回数が４回となるマスクＭとステップ回数が２回となる図１０のマスクの二種類を選択することになる。
【００４７】
また、この実施の形態では、図１０に示すように、基板Ｗの幅方向に３個描かれたマスクパターンＰが基板Ｗのステップ方向に二列（合計６個）配置されたマスクＭの寸法を１１００ｍｍ×７００ｍｍ（ステップ方向寸法ａ）とすることにより、１８インチディスプレイ用材ＤＰを９面取りする場合と１５インチディスプレイ用材ＤＰを１２面取りする場合とで、基板Ｗ及びマスクＭの大きさを同一にすることができる。
【００４８】
次に、選択されたマスクＭの大きさ及び基板Ｗのステップ回数について、最もタクトタイムが短くなり、且つ、必要な露光精度が得られる露光条件を露光照度とレジスト（基板に塗布された感光剤）感度との関係に基づいて選択する。
まず、タクトタイムの求め方について説明する。
基板ロード・ アンロード時間をＡ（ｓｅｃ／ｃｙｃｌｅ）＝ｃｏｎｓｔ、プロキシミティギャップ制御時間及びパターンアライメント制御時間をＢ（ｓｅｃ／ステップ) ＝ｃｏｎｓｔ、ステップ時のワークテーブル移動時間をＣ（ｓｅｃ／ステップ) 、露光時間をＤ（ｓｅｃ／ステップ) 、基板Ｗのステップ回数をｎとした場合に、ステップ回数がｎのときのタクトタイムＴ_n は次式（２）で求められる。なお、ＡおよびＢはステップ回数によらず一定値であり、ＣおよびＤはステップ回数により変化する。したがって、以下、ステップ回数により異なるものには添字を付けて表す。
【００４９】
Ｔ_n ＝Ａ＋Ｂ＋Ｄ_n ＋Ｃ_n ＋Ｂ＋Ｄ_n ＋Ｃ_n ＋……＋Ｄ_n
＝Ａ＋Ｂ＋Ｄ_n ＋( ｎ−１)(Ｃ_n ＋Ｂ＋Ｄ_n ) …（２）
また、ステップ時のワークテーブル移動時間Ｃは次式（３）で求められる。
Ｃ＝２ｖ／α_w ＋（ｘ−ｖ2 ／α_w ）／ｖ＝ｖ／α_w ＋ｘ／ｖ…（３）
但し、
ｖ：ワークテーブル移動速度（ｃｏｎｓｔ）
α_w ：ワークテーブル加減速値（ｃｏｎｓｔ）
ｘ：ステップ量（ステップ回数により異なる）
次に、図９（ａ）のマスクＭ（ステップ回数ｎ＝３）を用いた場合のタクトタイムＴ_n が図９（ｂ）のマスクＭ（ステップ回数ｎ＝２）を用いた場合のタクトタイムＴ_n より短くなる条件を次式（４）により求める。なお、ステップ回数ｎ＝３の場合の基板Ｗのステップ量ｘ₃ は３７７ｍｍ、ステップ回数ｎ＝２の場合の基板Ｗのステップ量ｘ₂ は７５４ｍｍとする。
【００５０】
△Ｔ_n ＝Ｔ₃ −Ｔ₂
＝( ２Ｃ₃ −Ｃ₂ ) ＋( ３Ｄ₃ −２Ｄ₂ ) ＋Ｂ
＝ｖ／α_w ＋１／ｖ( ２ｘ₃ −ｘ₂ ) ＋３Ｄ₃ −２Ｄ₂ ＋Ｂ
＝３Ｄ₃ −２Ｄ₂ ＋ｖ／α_w ＋Ｂ …（４）
ここで、△Ｔ_n ＝３Ｄ₃ −２Ｄ₂ ＋ｖ／α_w ＋Ｂ＜０、即ち、Ｄ₂ ＞３／２Ｄ₃ ＋Ｖ／２α_w ＋Ｂ／２の関係を満足すれば、基板Ｗのステップ回数ｎ＝３となるマスクＭの方が基板Ｗのステップ回数ｎ＝２となるマスクＭよりタクトタイムＴ_n が速くなる。
【００５１】
（４）式を用いてステップ回数ｎ＝２となるマスクＭの方がタクトタイムＴ_n が速くなる（△Ｔ_n ＞０）場合とステップ回数ｎ＝３となるマスクＭの方がタクトタイムＴ_n が速くなる（△Ｔ_n ＜０）場合の光源照度とレジスト感度との関係を計算により求めた結果を図１２に示す。なお、プロキシミティギャップ制御時間及びパターンアライメント制御時間Ｂを７ｓｅｃ、ワークテーブル移動速度ｖを３５０ｍｍ／ｓｅｃ、ワークテーブル加減速値α_w を１４００ｍｍ／ｓｅｃ ²として計算した。
【００５２】
図８に示す１８インチディスプレイ用材ＤＰを９面取りする基板Ｗに用いるマスクＭとしては、既に図９（ａ）のステップ回数ｎ＝３となるマスクＭ（ステップ方向寸法ａが７００ｍｍ）を選択しているので、図１２の３ステップ有利の領域内でできるだけ照度及びレジスト感度の大きな組み合わせを選択する。照度及びレジスト感度が定まれば対応する露光時間（（４）式のＤ₂ ，Ｄ₃ ) が定まる。これにより、ステップ回数が３回と多いにもかかわらず、タクトタイムＴ_n も２ステップの場合より短くすることができる。
【００５３】
一方、１５インチディスプレイ用材ＤＰを１２面取りする基板Ｗに用いるマスクＭとしては、ステップ回数が４回となるマスクＭとステップ回数が２回となる図１０のマスクＭの二種類が選択されているが、上記同様に（４）式を用いて光源照度とレジスト感度とステップ回数とタクトタイムとの関係を計算により求めたところ、図１３に示すように、照度にかかわらずステップ回数が２回となる図１０のマスクＭの方がステップ回数が４回となるマスクＭより常に有利であることが判った。従って、ステップ回数が２回となる図１０のマスクＭを選択する。
【００５４】
次に、図９（ａ）のステップ回数ｎ＝３となるマスクＭと図１０のステップ回数ｎ＝２となるマスクＭ毎にマスクＭ上の露光すべき領域の広さ（ステップ方向）に応じてステップ露光の照射領域Ｓ（図９及び図１０で２点鎖線で示す）を確保し且つ照度が大きくなるオプチカルインテグレータを選択する。そして、図１に示すように、選択された二種類のオプチカルインテグレータ３３ａ，３３ｂを照明光学系３の凹面鏡３２の焦点近傍に配置し、マスクＭの種類の応じて照射領域切替手段２００Ａを用いて互いに切替えて露光を行う。
【００５５】
なお、照射領域Ｓは図９（ａ）のマスクＭの場合で１０００ｍｍ×４００ｍｍ（ステップ方向寸法）、図１０のマスクＭの場合で１０００ｍｍ×６００ｍｍ（ステップ方向寸法）としている。また、二種類のオプチカルインテグレータ３３ａ，３３ｂは、ステップ方向（Ｙ軸方向）のみの照射領域が変わるような関係となっており、従って、Ｘ軸方向の照射領域は一定である。
【００５６】
図１５に示すように、各オプチカルインテグレータ３３ａ，３３ｂの内で一方のオプチカルインテグレータ３３ａのレンズ面の曲率半径Ｒ１は、他方のオプチカルインテグレータ３３ｂのレンズ面の曲率半径Ｒ２より大きくされており（Ｒ１＞Ｒ２）、オプチカルインテグレータ３３ａの射出角はオプチカルインテグレータ３３ｂの射出角より大きくなっている。従って、オプチカルインテグレータ３３ａを用いた場合のステップ方向（Ｙ軸方向）の照射領域Ｓ_y1はオプチカルインテグレータ３３ｂを用いた場合のステップ方向（Ｙ軸方向）の照射領域Ｓ_y2より広くなり、前者が図１０のステップ回数が２回となるマスクＭに対応し、後者が図９（ａ）のステップ回数ｎ＝３となるマスクＭに対応している。
【００５７】
照射手段切替手段２００Ａは、二種類のオプチカルインテグレータ３３ａ，３３ｂと、切替機構２００とによって構成されている。
切替え機構２００は、図１６に示すように、２種類のオプチカルインテグレータ３３ａ，３３ｂがそれぞれ支持部２０１ａ，２０１ｂを介して固定される交換用ステージ２０２を備えており、該交換用ステージ２０２はガイドレール２０３とスライダ２０４とを具備するリニアガイド２０５のスライダ２０４に固定されてスライダ２０４と一体となってガイドレール２０３に沿って移動可能とされている。
【００５８】
交換用ステージ２０２の移動方向の一端には把手２０６が設けられており、該把手２０６を押し引きすることにより、オプチカルインテグレータ３３ａ又はオプチカルインテグレータ３３ｂの中心が照明光学系３の光軸Ｌと一致するように位置決めされる。
そして、図１０のステップ回数ｎ＝２となるマスクＭの場合には、射出角の大きいオプチカルインテグレータ３３ａの中心を照明光学系３の光軸Ｌに位置決めし、この状態で露光を行うことにより、図１４（ａ）に示すように、ステップ方向に広い照射領域Ｓ_y1が得られ、図９（ａ）のステップ回数ｎ＝３となるマスクＭの場合には、射出角の小さい側のオプチカルインテグレータ３３ｂの中心を照明光学系３の光軸Ｌに位置決めし、この状態で露光を行うことにより、図１４（ｂ）に示すように、ステップ方向に狭い照射領域Ｓ_y2が得られる。
【００５９】
なお、この実施の形態では、オプチカルインテグレータ３３ａ，３３ｂとしてフライアイレンズを用いて、フライアイレンズ全体を切り替えるようにしているが、これに代えて、オプチカルインテグレータ３３ａ，３３ｂとして組レンズ、あるいはフライアイレンズと組レンズの組合せ等を用いて、一部のレンズのみを切り替えるようにしてもよい。
【００６０】
図１７に切替え機構の変形例を示す。
この切り替え機構３００は、互いに射出角の異なる４種類のオプチカルインテグレータ３３ａ〜３３ｄを保持する回転ホルダ３０１と、照明光学系３の本体（図示せず。）に固定され回転ホルダ１５を所定角ずつ回転させて各オプチカルインテグレータ３３ａ〜３３ｄをマスクサイズの変更に応じて照明光学系３の光軸Ｌと一致するように位置決めする回転駆動モータ３０２とを備えたもので、３種類以上のマスクＭを用いる場合に有効なものである。
【００６１】
次に、上記構成の分割逐次近接露光装置の作動を説明する。
例えば、カラーフィルタ形大型液晶ディスプレイ用のＲＧＢカラーフィルタに所定のパターンを形成する場合、ガラス基板Ｗ上に先ず各画素間を仕切るブラックマトリックスのパターンをレジスト塗布した後に酸素遮断膜を塗布し、次いで、露光、現像の各工程を経る。このようにブラックマトリックスのパターンが形成された基板Ｗ上に、Ｒ（赤），Ｇ（緑），Ｂ（青）の三原色の個々のパターンを各色毎にブラックマトリックスのパターン形成と同様の工程を繰り返しながら形成していく。ここでは、基板Ｗ上に最初に形成するブラックマトリックスのパターンを「一層目」、一層目の上に形成する三原色のいずれかのパターンを「二層目」、次に形成する三原色の他のいずれかのパターンを「三層目」、更にその次に形成する三原色の残りのパターンを「四層目」という。
【００６２】
ここでは、一層目のステップ露光に際して、図８に示す１８インチディスプレイ用材ＤＰを９面取りする基板Ｗでステップ回数ｎ＝３とし、マスクとして図９（ａ）のマスクＭを用いる場合を例に取り、大型液晶ディスプレイ用のカラーフィルタのガラス基板Ｗの上に一層目のブラックマトリックスのパターンを三分割逐次近接露光により形成する。
【００６３】
分割逐次近接露光装置のマスクステージ１の下面には、一層目のパターンが描かれたマスクＭが予め真空吸着により装着されている。また、ワークステージ２は、Ｙ軸方向の前進限近傍に位置し且つＺ軸方向の最下限迄下降している。
（１）アライメントのためのギャップ調整
まず、ギャップ調整手段６を構成するＺ軸送り台６の上下粗動装置６１を駆動してワークステージ２を予め設定してある粗動上限目標位置（例えばマスクＭの表面から数ｍｍ程度の位置）まで急速上昇させる。この粗動時には、ギャップセンサ１５によるワークチャック８の上面（実際にはその上に固定されたガラス製の被検部８ｍ上面）とマスクＭとのすき間間隔（ギャップ）の計測は行わない。
【００６４】
次に、Ｚ軸送り台６の３台の上下微動装置６３を駆動してそのクサビ作用によりワークステージ２を微動で上昇させ、これにより、ワークステージ２とマスクＭとを近接させる。この微動時には、図５に示すように、マスク側アライメントマーク７６を有するマスクＭの表面と、ワーク側アライメントマーク７５を有するワークチャック８の面との間のギャップをギャップセンサ１５により計測し、その計測結果を上下微動装置６３の制御装置（図示せず。）に出力し、該制御装置は予め設定してあるアライメント時の目標ギャップ量と一致するように上下微動装置６３を制御してワークステージ２を上昇させる。
【００６５】
このように、ギャップ調整手段６の上下動の速度を二速に分けて、ワークステージ２の上昇距離の大部分を上下粗動装置６１で高速上昇させるとともに、最終的には上下微動装置６３でワークステージ２を微動且つ高精度で上昇させるようにしているため、分割逐次近接露光におけるギャップ調整作業の高速化と高精度化を同時に達成することができる。
（２）アライメント調整
このようにして、ワークステージ２とマスクＭとを近接させた状態においては、基板Ｗのステップ方向（Ｙ軸方向）とマスクＭとの相対位置及び姿勢が正しく整合していない場合、例えば図７（ａ）に示すように、ワークステージ２に対してマスクパターンＰを有するマスクＭが角度θだけ傾斜している場合（ワークステージ２の向きとＹ軸方向の向きとは一致しているとして）には、ワーク側アライメントマーク７５とマスク側アライメントマーク７６とは整合せず、ずれてしまう。従って、このまま１ステップ目のマスクパターンＰの露光転写を行うと、次ステップ目で同一の基板Ｗ上に形成される分割パターンＰとのずれが生じて、精度の良いブラックマトリックスのパターンが得られない。
【００６６】
そこで、ワーク側アライメントマーク７５とマスク側アライメントマーク７６との整合作業（アライメント）をアライメントカメラ１６を用いて行い、このときピント調整機構１６１によって両マーク７５，７６の双方にピントを合わせる。
一層目のステップ露光では、アライメントの際に、図５を参照して、投影用光学系７８でワーク側アライメントマーク７５を下から照射すると共に、露光時に用いるギャップセンサ１５を利用してワーク側アライメントマーク７５を有するワークチャック８の表面（被検部）８ｍとマスク側アライメントマーク７６を有するマスクＭの表面（マスクマーク面Ｍm ）との間のギャップを設定することにより、両マーク７５，７６にアライメントカメラ１６のピントをほぼ合わせて両マーク７５，７６のずれを検出する。
【００６７】
なお、通常、マスクＭの板厚は５ｍｍ，８ｍｍ，１０ｍｍなどと規格化されているため、従来のアライメントカメラのように一つの固定焦点を持つものではマスク厚の変更もしくはばらつきに対して即応できず、アライメントマークの検出精度が低下するという問題を有するが、この実施の形態では、ピント調整機構１６１に予め種々のマスク板厚に対応するアライメントカメラ１６のフォーカス位置を予めセットしておくことにより、マスクＭの交換によるマスク厚の大幅な変化に即応して、アライメントカメラ１６のピントをベストフォーカス位置であるマスクマーク面Ｍm に位置決めすることができる。
【００６８】
また、ピントずれを検出するのにギャップセンサ１５で実際のマスク下限位置を計測し、その計測値を計算機９２に出力して予めマスク下面（マスクマーク面Ｍm ）に設定しておいたピント位置（目標位置）からの相対ピント位置変化量を計算してその分だけピント調整機構１６１を操作してアライメントカメラ１６の位置を補正しているので、例えばマスク厚のばらつきによるピントずれを調整してマスクマーク７６に対するベストフォーカスを保証することができる。
【００６９】
そして、ピントが適正に調整されたアライメントカメラ１６によってワーク側アライメントマーク７５とマスク側アライメントマーク７６との間にずれが検出されると〔図７（ａ）〕、その検出信号をマスク位置調整手段１４の制御装置（図示せず。）に出力し、該制御装置によってＸ方向駆動装置１４ｘ及び二つのＹ方向駆動装置１４ｙの駆動を制御することにより、マスク保持枠１３の姿勢を修正して両マーク７５，７６を図７（ｂ）に示すように整合させる。これにより、マスクＭとＹ軸方向との傾きθ（同図は、基板Ｗの長辺方向とＹ軸方向と、マスクＭの短辺方向とマスクパターンＰの短辺方向とが、それぞれ平行である場合を示している）が解消される。
（３）基板Ｗの挿入及び１ステップ目の露光
アライメント終了後、ギャップ調整手段６により一旦ワークステージ２を必要なだけ下降させる。この状態で、ワークステージ２とマスクステージ１との間隔（例えば６０ｍｍ程度）を利用して、ワーク自動供給装置（図示せず。）により基板Ｗをワークステージ２上に投入し、該ワークステージ２上のワークチャック８に保持する。その後、再度ギャップ調整手段６により、マスクＭの下面とワークＷ上面とのすき間を、露光する際に必要な所定の値となるように調整する。その手順は、ギャップセンサ１５により計測されるのがマスクＭの下面と基板Ｗ上面とのギャップである点を除けば、前記（１）と同じ手順である。
【００７０】
なお、ギャップ調整手段６によりワークステージ２を上下動させる際に、わずかではあるがワークステージ２がＸＹ平面内でも多少動いてしまう場合もある。このような場合のために、上記（２）のアライメント終了後での各レーザ干渉計７４３、７４４、７４４による位置データを、前記補正制御手段により記憶しておき、ギャップ調整後の位置データが記憶されているデータとは変わっている場合には、マスク位置調整手段１４で変化分だけ補正することにより、マスクＭの向きとＹ軸方向との傾きのない状態に戻すことができる。
【００７１】
次に、切替え機構２００を操作して射出角の小さい側のオプチカルインテグレータ３３ｂの中心を照明光学系３の光軸Ｌに位置決めし、この状態で照明光学系３の露光制御用シャッター３４を開制御して１ステップ目の露光を行い、マスクＭのマスクパターンＰを基板Ｗの所定位置に焼き付けて、基板Ｗ上に第１の分割パターンＰ1 を得る。
（４）２ステップ目の露光位置へのワークステージ２の移動
続いて、第２の分割パターンＰ2 のつなぎ露光を行うために、ワークステージ送り機構７の送り駆動装置７３を駆動してワークステージ２を移動させることにより、ワークステージ２をマスクＭに対して図７（ｂ）の矢印Ｙ方向に１ステップ量だけ送り、基板Ｗを２ステップ目の露光位置に配置する。このとき、基板ＷとマスクＭとの干渉を避けるため、ワークステージ２を必要な分だけＺ軸方向に下降させるようにしてもよい。
（５）ワークステージ２の送り誤差によるアライメント調整
上記のようにワークステージ２をマスクＭに対して図７（ｂ）の矢印Ｙ方向に１ステップ量だけ送る際には、先にのべた要因による送り誤差が生じるため、そのまま２ステップ目の露光をすると第２の分割パターンＰ2 がわずかではあるが位置ずれをおこす。例えば、ワークステージ２のステップ送り中にワークステージ２のヨーイングと真直度のエラーにより、図７（ｃ）のように真直度Δｘ、傾斜角度θ’だけ正規位置からずれてしまう。
【００７２】
そこで、基板Ｗ上に第２の分割パターンＰ2 を露光転写する前に、基板Ｗの送り誤差を送り誤差検出手段７４で検出してその検出結果をつなぎ露光位置を補正する補正制御手段に出力し、該補正制御手段では該検出結果に基づいてつなぎ露光のための位置決め補正量を算出し、その算出結果に基づいてマスク位置調整手段１４（及び送り時のピッチング補正など、必要に応じてギャップ調整を行うために上下微動装置６３）のＸ軸方向駆動装置１４ｘ及びＹ軸方向駆動装置１４ｙを制御してマスク保持枠１３の位置を調整し、マスクＭの位置ずれを補正するアライメント調整を行う。なお、ギャップ調整手段６によるマスクＭと基板Ｗとのギャップ調整を行った場合は、その後の状態でのヨーイング及び真直度のデータに基づいて前記アライメント調整を行う。
（６）２ステップ目の露光
その後、照明光学系３の露光制御用シャッター３４を開制御して２ステップ目の露光を行い、マスクＭのマスクパターンＰを基板Ｗの所定位置に焼き付けて、基板Ｗ上に位置ずれが修正された第２の分割パターンＰ２を得る（図７（ｄ）参照）。
（７）３ステップ目の露光
３ステップ目の露光については、前記（４），（５）及び（６）ど同様にして２ステップ目の露光位置へのワークステージ２の移動、ワークステージ２の送り誤差によるアライメント調整及び３ステップ目の露光を行い、基板Ｗ上に位置ずれが修正された第３の分割パターンＰ３（図示せず。）を得る。
【００７３】
上記の説明から明らかなように、この実施の形態では、マスクＭの大きさ及び基板Ｗのステップ回数を、マスクＭのたわみ量、得るべき露光精度及びマスクＭのパターン領域の大きさから選択し、更に、選択されたマスクＭの大きさ及び基板Ｗのステップ回数について、最もタクトタイムが短くなり、且つ、必要な露光精度が得られる露光条件を露光照度とレジスト感度との関係に基づいて選択し、更に、選択されたマスクＭ毎にマスクＭ上の露光すべき領域の広さ（ステップ方向）に応じてステップ露光の照射領域Ｓを確保し且つ照度が大きくなるオプチカルインテグレータを選択してステップ露光を行うようにしているので、フラットパネルディスプレイの多面取り露光において、決められた大きさの基板に高精度且つ高スループットでステップ露光することができる。
【００７４】
なお、上記実施の形態では、レーザ干渉計７４３，７４４等の送り誤差検出手段７４を備えた分割逐次近接露光装置に本発明を適用した場合を例に採ったが、これに限定されず、送り誤差検出手段７４を備えていない分割逐次近接露光装置にも本発明を適用できるのは勿論である。
また、上記実施の形態では、１層目のステップ露光を例に採ったが、これに限定されず、２層目以降のステップ露光を主とするアライメントマークのみによる位置決めを行うタイプにも本発明を適用してもよい。
【００７５】
図１８は本発明の第２の実施形態を示す図である。なお、このものは、本発明の分割逐次近接露光装置におけるアライメントマークの投影結像に係わる構造、特にワーク側アライメントマーク７５をワークチャックの下からマスクアライメントマーク面に投影する光学系の変形例であり、その他の上記第１の実施形態と同様の構成部分の重複する説明は省略する。即ち、本実施形態の投影光学系７８Ａは、ワークチャック８の下方に、光源７８１，コンデンサーレンズ７８２，ワーク側アライメントマーク７５を配設すると共に更にそのワーク側アライメントマーク７５の上位に結像レンズ７８３を配してある点が上記第１の実施形態の投影光学系７８と異なっている。
【００７６】
結像レンズ７８３を、その一方の焦点上にワーク側アライメントマーク７５が位置し、他方の焦点上にマスクＭのマスクマーク面Ｍm が位置するように配設することにより、ワーク側アライメントマーク７５をマスク側アライメントマーク７６と同一レベルに投影結像することができる。
上記第２の実施形態によれば、このように、アライメント時にワーク側アライメントマーク７５を外部から光学的にマスク側アライメントマーク７６上に一致させてピントを合わせることができて、ワーク側アライメントマーク７５とマスク側アライメントマーク７６とが検出光学系からデフォーカスされることが全くなく、理想的なパターンを検出できるので、より高精度に１層目の分割逐次近接露光が可能になるという効果がある。
【００７７】
図１９は本発明の第３の実施形態を示す図である。このものは、本発明の分割逐次近接露光装置におけるアライメントマークの投影結像に係わる構造のうち、特にアライメント画像のベストフォーカス調整機構の変形例であり、その他の上記第１の実施形態と同様の構成部分の重複する説明は省略する。
即ち、本実施形態のアライメント画像のベストフォーカス調整機構９Ａは、アライメントカメラ１６及びピント調整機構１６１と計算機９２Ａからなり、アライメントカメラ１６で撮像されたマスクＭのマスクマーク面Ｍm にあるマスク側アライメントマーク７６のパターンの像７６ｚのコントラストを検出走査線で計測し、その画像コントラストの微分波形７７の波高Ｄ，Ｄ’が最大となる状態をピント調整機構１６１でカメラ１６を動かしながら探す。これにより、パターン像７６ｚが最もシャープに写るカメラ位置を得て、より一層高精度のアライメントが実現できるという利点がある。また、上記第２の実施形態と同じく、任意のマスク厚及びマスク厚のばらつきに対しての検出光学系への影響が全く無く、いずれのマスク厚に対しても高精度の検出が可能という効果が得られる。
【００７８】
なお、以上のようにして一層目（すなわちブラックマトリックス）のパターン露光が終了すると、現像などの所定の工程を経て、二層目、三層目…とそれぞれのパターン露光を含む工程を経て仕上げられる。通常、カラーフィルタ等はライン設備で生産され、露光装置も一層目、二層目…とそれぞれ専用の装置が用いられる。
【００７９】
二層目以降のための露光装置としても勿論、本発明の装置すなわちワーク側アライメントマーク７５を用いたマスク位置調整手段を備えて、ワークステージの送り誤差を検出し、補正してつなぎ露光をする分割逐次近接露光装置を用いることができる。しかし、一層目の露光パターンの中に二層目以降のアライメントのために用いるマークのパターンを含ませておけば、二層目以降の露光時には、ワークに形成されたこのマークを基準にアライメントを行えばよく、この場合には、二層目以降のための露光装置には、ワーク上のアライメントマークとマスク上のアライメントマークとのアライメントを行う機能を備えた従来の露光装置であればよい。
【００８０】
しかしながら、このような従来の露光装置では、前記のとおり一層目の分割パターン同士のつなぎ目の高精度な整合のための仕組が考慮されていない。一層目の露光装置として本発明のものを用いたライン設備で生産することにより、高精度なつなぎ目の整合が実現できるのである。すなわち、一層目の露光装置にワーク側アライメントマークを用いた前記のようなマスク位置調整装置手段を使用することにより、ワークステージの送り方向とマスクパターンの向きとをそろえることができ、つなぎ目の整合が可能となる。そして、その際にワークスデージの送り誤差を検出し、これを補正することで更に高精度なつなぎ目の整合が可能となる。
【００８１】
以下に、第４の実施形態として、二層目以降の露光専用の機能を付加した本発明の分割逐次近接露光装置により、二層目露光を行う場合のアライメント調整について説明する。
従来の露光装置を用いて二層目以降のつなぎ露光を行う場合、第１ステップ目の露光のワークアライメント完了後に、ワークステージ２を第２ステップ目の露光位置に向かってＹ方向に送り移動させる際には、ワークステージ２の送り精度を頼りにしてそのまま送るか、もしくはワークステージ２の送り誤差（Ｙ軸の進行方向の傾き）に基板Ｗの搭載姿勢をできるだけ合わせて送ってから、第２ステップ目のアライメントを行うという方法がとられている。
【００８２】
しかし、そうした方法では、第２ステップ目のワーク側アライメントマーク７５を検出する際に、ワークステージ２上に基板Ｗを投入して搭載した時の基板Ｗの傾き精度（傾斜角θw の大きさ）とワークステージ送り量ｙの大きさ如何によっては、第２ステップ目の位置におけるワーク側アライメントマーク７５がアライメントカメラ１６の視野内に入らない場合があり、ワーク側アライメントマーク７５を視野内に捕捉するのに時間がかかりワークアライメントに相当長時間を要したり、最悪の場合第２ステップ目のワークアライメントが不可能になるという問題がある。
【００８３】
本実施形態は、二層目以降の露光におけるこのような問題を解決することができるものであり、図２０（ａ）〜（ｄ）を参照しつつ具体的に説明する。装置は、先に説明した本願発明の分割逐次近接露光装置を適用する。なお、第２ステップ目までを説明しているが、それ以降のステップにおいても同様に適用できるものである。
【００８４】
第１工程〔図２０（ａ）〕：
二層目露光の前準備の段階である。
二層目露光用のマスクＭをマスクステージ１に装着する。装着した二層目露光用のマスクＭのマスクマーク７６，７６を、それぞれ各アライメントカメラ１６の視野Ａ，Ａの中心に合わせる。そして、ワークステージ２を第２ステップ目の位置へ送る前に、ワークステージ２の実際の送り方向（Ｙ’方向）に対するアライメントカメラ１６の視野Ａの中心軸（すなわち、左右２台のアライメントカメラ１６の視野Ａ，Ａの中心同士を結んだ軸線）ＸA の直交度のずれ角θm （以下マスクずれ角θm という）を予め求めておく。
【００８５】
このマスクずれ角θm は、マスクＭのＹ軸とその実際の相対的送り方向Ｙ’とのずれ角度であり、一層目の露光時においてのＹ軸の走り方向とワーク側アライメントマーク７５との傾き角θ（図７参照）と同様であり、その場合のワーク側アライメントマーク７５をカメラ視野Ａに置き換えたと同じである。マスクずれ角θm の具体的な求め方の例を後述する。
【００８６】
第２工程〔図２０（ｂ）〕：
一層目露光の終わった基板Ｗを、ワークステージ２上に投入して装着する。基板Ｗは通常、ワークステージ２の実際の送り方向Ｙ’に対して時計回り（プラス）又は反時計回り（マイナス）方向に相対的に傾斜した状態で装着される。図２０（ｂ）はこの基板Ｗの装着直後の状態を示している。送り方向Ｙ’に対する基板Ｗの傾斜角θW は、十字形のワーク側アライメントマーク７７の中心同士を結んだ軸線（以下、ワークアライメント軸線という）ＸW とワークステージ２の実際の送り方向Ｙ’に直交する軸ＸY とのなす角（以下、ワーク傾斜角θW という）である。
【００８７】
この場合、ワーク側アライメントマーク７７とマスク側アライメントマーク７６７６とは未だずれがあり、そのずれ角度（マスク傾斜角度）αはワークアライメント軸線ＸW とカメラ視野Ａの中心軸線ＸA とのなす角に相当している。すなわち、この場合のワーク傾斜角θW はθW ＝θm ＋（マイナスα）となり、マスクＭの前記ずれ角θm よりマスクＭと基板Ｗとのずれ角αだけ反時計方向に小さくなる。
【００８８】
第３工程〔図２０（ｃ）〕：
二層目露光の第１ステップ目である。装着した基板ＷとマスクＭとのアライメントを行い、両者のずれを無くす。すなわち、基板Ｗに対してマスクＭを移動しずれを解消する。具体的には、マスク位置調整手段１４の操作によりマスクＭをＺ軸回りに反時計方向に旋回させて、十字のワーク側アライメントマーク７７に対し方形のマスク側アライメントマーク７６を合わせる。その時のマスクＭの旋回角度すなわちマスク傾斜角度αを露光位置補正制御手段の記憶装置に記憶させる。図２０（ｃ）は、二層目露光における第１ステップ目のワーク側アライメントマーク７７とマスク側アライメントマーク７６とのアライメント完了時の状態を示している。この後、第１ステップ目の露光が行われる。
【００８９】
第４工程〔図２０（ｄ）〕：
第１ステップ目の露光完了後、ワークステージ送り機構７により第２ステップ目の露光位置にワークステージ２を送る。その送り操作において、Ｙ軸方向送りを検出するレーザ干渉計７４４で送り量（距離）ｙが計測される。次いで、マスクＭを反時計方向にワーク傾斜角θW だけ旋回させて第２ステップ目のアライメントを開始するのであるが、その前に、マスクステージ１のマスク位置調整手段１４によりマスクＭの位置補正を行う。具体的には、前記ワークステージ２の送り量（距離）ｙ及び第１工程で求めたマスクずれ角θm ，第３工程で求めたマスク傾斜角度αを用いて、次式によりマスクステージ１のＸ軸方向の補正量ΔＸを算出する。
【００９０】
ΔＸ＝ｙ・ｓｉｎ（θm ＋α）
そして、このΔＸの距離だけマスクステージ１をＸ方向に移動させてその位置を補正する。このマスク位置補正により、第２ステップ目用の十字のワーク側アライメントマーク７７及び方形のマスク側アライメントマーク７６がアライメントカメラ１６の視野内に必ず入ることになる。したがって、第２ステップ目以降のワーク側アライメンントマークの検出において、基板Ｗ搭載時の傾斜角θW の大きさや、Ｙ方向送り量の如何にかかわらずアライメントエラーが全く発生しなくなる。かつまた、装置のタクトタイムが大幅に短縮される。
【００９１】
さらに、理論的には、２ステップ目以降のワークアライメントは、上記計算とその補正を正確に行うことにより、視野に入った時点でアライメント完了位置にマスクステージが移動するので、第２ステップ目のアライメントが必要なくなる（即ち、補正制御手段の指令でマスク位置調整手段１４を作動させて自動的にアライメントが行われ、１回のアライメントで、２ステップ更にはｎステップの露光が可能となる。）
かくして、第２ステップ目以降のワークアライメントが必要でないグローバルアライメント露光が可能となり、装置タクトタイムの一層の短縮と、精度向上との両立ができる。
【００９２】
上記第４の実施の形態では、二層目露光における第２ステップ目以降のワーク側アライメントマーク７７を検出するに当たり、一層目露光時に予め求めておいたワークステージ２の実際の送り方向Ｙ’と二層目露光時の第１ステップ目のワークアライメントの結果から基板Ｗ姿勢を認識して、マスクステージの位置を修正することにより、二層目露光の第２ステップ目以降はワーク側アライメントマークを必ずアライメントカメラの視野内に捕捉するように制御する場合を説明したが、このような制御方法は必ずしも二層目露光以降にのみ適用するとは限らない。ワークステージ２の実際の送り方向Ｙ’を予め試験的に把握しておくことで、一層目露光のワーク側アライメントマークの傾斜角θとワークステージの走り方向の傾きθの場合にも適用可能である。
【００９３】
ここで、前記マスクずれ角θm の求め方の一例を述べる。
図２１（ａ）は、二層目露光における第１ステップ目の状態である。すなわち、前記図２０（ａ）と同じく、マスクＭのマスク側アライメントマーク（□印）７７A ，７７B を、それぞれ各アライメントカメラの視野ＣＡ，ＣＢ（○印）の中心に合わせる。この時の、ワークステージの実際の走り方向Ｙ’と直交する軸ＸY に対するカメラの視野中心軸線ＸA のずれ角θm を、予め次の方法で測定する。
【００９４】
▲１▼ワークステージを送り、マスクＭを第２ステップ目の位置に相対移動させる。その実際の送り方向はＹ’方向であるから、第１ステップ目の位置Ｉにあるワーク側アライメントマーク７７AI及び７７BIは、Ｙ’方向に沿った位置ＩＩに移動してワーク側アライメントマーク７７AII 及び７７BII になる〔図２１（ｂ）〕。
【００９５】
▲２▼測定基準を７７BI−７７BII を結ぶ線Ｌｓとし、この基準線ＬｓがＸ方向になるように基板Ｗを水平旋回する。そして、基準線Ｌｓに対する直線７７BI−７７AI及び７７BII −７７AII の傾き角θm1，θm2を求める〔図２１（ｃ）〕。
θm ＝（θm1＋θm2）／２
＝（ｔａｎ-1ｇ1 ／Ｇ1 ＋ｔａｎ-1ｇ2 ／Ｇ2 ）／２
である。
【００９６】
なお、高精度化のために、ｎステップまで行ってその平均をとっても良い。
θm ＝（θm1＋θm2＋……＋θmn）／ｎ
なお、上記各実施形態では、マスクステージ１をマスクステージ支持台１２で装置ベース４に固定して取り付け、ワークステージ２の方のみギャップ調整手段６で昇降させる構造を示したが、これに限らず、例えばマスクステージ支持台１２をシリンダで構成してマスクステージ１の方を昇降させる構造にしてもよい。その場合には、上下粗動装置を有するＺ軸粗動ステージ６２を省略することができる。
【００９７】
また、上記各本実施の形態ではワークステージをＹ軸方向に移動可能な構成としたが、代わりにマスクステージと露光手段とをＹ軸方向に移動可能な構成としても良い。
【００９８】
【発明の効果】
上記の説明から明らかなように、本発明によれば、フラットパネルディスプレイの多面取り露光において、決められた大きさの基板に高精度且つ高スループットでステップ露光することができるという効果が得られる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態である分割逐次近接露光装置を説明するための一部を分解した説明的斜視図である。
【図２】マスクステージ部分の拡大斜視図である。
【図３】（ａ）は図２のIII − III線断面図、（ｂ）は（ａ）のｂ矢視で示す平面図である。
【図４】アライメントカメラと該アライメントカメラのピント調整機構の基本構造を示す側面図である。
【図５】ワーク側アライメントマークの照射光学系を説明するための説明図である。
【図６】アライメント画像のフォーカス調整機構を示す構成図である。
【図７】ステップ露光を説明するための説明図である。
【図８】１８インチディスプレイ用材ＤＰを９面取りした基板Ｗ（１０００ｍｍ×１２００ｍｍ）の平面図である。
【図９】図８の基板に対向配置されるマスクを示す図であり、（ａ）は３ステップ露光の場合に用いるマスクの平面図、（ｂ）は２ステップ露光の場合に用いるマスクの平面図である。
【図１０】１５インチディスプレイ用材ＤＰを１２面取り（長辺方向４×短辺方向３）した基板Ｗ（１０００ｍｍ×１２００ｍｍ）に対向配置されるマスクを示す図であり、２ステップ露光の場合に用いるマスクの平面図である。
【図１１】マスクの横（短辺）寸法を一定にした場合の該マスクの縦（長辺）寸法と自重による最大たわみ量との関係を示すグラフ図である。
【図１２】図９（ａ），（ｂ）の各マスクを用いた場合の光源照度とレジスト感度とステップ数とタクト時間との関係を示すグラフ図である。
【図１３】図１０のマスクと図示しない４ステップ露光用マスクとを用いた場合の光源照度とレジスト感度とステップ数とタクト時間との関係を示すグラフ図である。
【図１４】照射領域切替手段による照射領域の切替え操作を説明するための図であり、（ａ）は照射領域を広げた状態を示す図、（ｂ）は照射領域を狭めた状態を示す図である。
【図１５】二種類のオプチカルインテグレータを示す図であり、（ａ）はレンズ面の曲率半径が大きいタイプの側面図、（ｂ）はレンズ面の曲率半径が小さいタイプの側面図である。
【図１６】照射領域切替手段の切替え機構の一例を説明するための斜視図である。
【図１７】切替え機構の変形例を説明するための斜視図である。
【図１８】本発明の第２の実施の形態である分割逐次近接露光装置を説明するための説明図である。
【図１９】本発明の第３の実施の形態である分割逐次近接露光装置を説明するための説明図である。
【図２０】本発明の第４の実施の形態である分割逐次近接露光装置を説明するための図であり、（ａ）は露光前準備とマスクロード後のアライメントを示す模式図、（ｂ）はワークロード直後を示す模式図、（ｃ）は第１ステップ目のアライメントメント完了状態を示す模式図、（ｄ）は第２ステップ目のアライメントメントに移動後の状態を示す模式図である。
【図２１】マスクずれ角θm の求め方を説明する図で、（ａ）は二層目露光における第１ステップ目の状態を示す平面図、（ｂ）はマスクＭを第２ステップ目の位置に相対移動させた状態を示す平面図、（ｃ）はマスクずれ角θm1，θm2の測定時の状態を示す平面図である。
【符号の説明】
Ｗ…基板
Ｍ…マスク
Ｐ…マスクパターン
１…マスクステージ
２…ワークステージ
３…照明光学系（照射手段）
６…ギャップ調整手段
７…ワークステージ送り機構
３３ａ，３３ｂ…オプチカルインテグレータ
２００Ａ…照射領域切替手段
２００…切替え機構[0001]
BACKGROUND OF THE INVENTION
The present invention is suitable for proximity exposure transfer of a mask pattern of a mask on a substrate of a material such as glass used for a large flat panel display such as a liquid crystal display or a plasma display by a divided sequential exposure method. The present invention relates to a division sequential proximity exposure apparatus and an exposure method.
[0002]
[Prior art]
In the proximity exposure, a translucent substrate (material to be exposed) coated with a photosensitive agent on the surface is held on the work stage of the proximity exposure apparatus, and the substrate is brought close to the mask held on the mask stage. The gap is set to several tens of μm to several hundreds of μm, and then exposure light is irradiated onto the substrate by an irradiation device from the side away from the substrate of the mask, whereby the mask pattern drawn on the mask is exposed and transferred onto the substrate. It is what I did.
[0003]
Recently, there has been a demand for mass production of large liquid crystal displays, plasma displays, and the like. In this case, it is necessary to improve the exposure accuracy and efficiency.
As an example of high efficiency, for example, as shown in FIG. 8, there is a so-called multi-sided method in which a plurality of displays are made with a single substrate W. In this example, nine 18-inch display materials DP can be produced on a substrate W of 1000 mm × 1200 mm.
[0004]
Further, for example, a 15-inch display material DP can be made for 12 surfaces (long side direction 4 × short side direction 3) on a substrate (1000 mm × 1200 mm) W of the same size, and further, a 17-inch display material DP can be formed. It is also possible to make nine 14-inch display materials DP for 14 inches.
On the other hand, the size of the mask (for example, quartz glass) is limited due to the accuracy and cost of the mask pattern, and it is currently reasonable to make a mask that is the same size as the substrate and can be exposed at once. I can't say that.
[0005]
Under such circumstances, conventionally, a mask smaller than the substrate W is used, and the substrate W is moved stepwise with respect to the mask in a state where the mask is disposed close to and opposed to the substrate W. A plurality of mask patterns drawn on the mask are exposed and transferred onto the substrate W to create a plurality of display materials DP on a single substrate W. Proximity exposure methods have been proposed (see, for example, JP 2000-35676 A and JP 9-127702 A).
[0006]
As the mask M in this case, assuming that the substrate W is 1000 mm × 1200 mm, as shown in FIG. 9A, three mask patterns P are drawn in the short direction of the substrate W, or FIG. As shown in b), a pattern in which three mask patterns P drawn in the short direction of the substrate W are arranged in two rows (6 in total) in the longitudinal direction of the substrate W is considered. The number of times (longitudinal direction of the substrate) is 3 times (the first exposure position is 1 step), and the latter is 2 times.
[0007]
[Problems to be solved by the invention]
However, in the conventional divided sequential proximity exposure apparatus, there is no disclosure as to what mask size is selected and what exposure conditions can be used to achieve both high exposure accuracy and high throughput. There was room for further improvement.
The present invention has been made paying attention to such a technical problem, and in a multi-face exposure of a flat panel display, a divided sequential proximity exposure apparatus that performs step exposure on a substrate of a predetermined size with high accuracy and high throughput. And an exposure method.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a division sequential proximity exposure apparatus according to claim 1 includes a work stage that holds a substrate as a material to be exposed, and a mask that is opposed to the substrate and holds a mask smaller than the substrate. A stage, irradiation means for irradiating the substrate with light for pattern exposure via the mask, and the work stage and the mask so that the mask pattern of the mask faces a plurality of predetermined positions on the substrate A work stage feed mechanism for moving the stage relative to the step; and a gap adjusting means for adjusting a gap between the opposing surfaces of the mask and the substrate, wherein the number of steps of the work stage feed mechanism is two or more. In the divided sequential proximity exposure apparatus in which the mask pattern is exposed and transferred onto the substrate for each step,
The size of the mask and the number of steps are determined based on the relationship between the resist sensitivities and the exposure illuminance at which the allowable deflection amount of the mask, the size of the pattern area of the mask and the tact time are shortest and the required exposure accuracy is obtained. Further, the irradiation means includes an irradiation area switching means capable of switching the irradiation area in the step direction of the light for exposure according to the exposure condition at the set number of steps.
[0009]
A divided sequential proximity exposure apparatus according to a second aspect of the present invention is the divided sequential proximity exposure apparatus according to the first aspect, wherein the irradiation region switching unit includes a plurality of types of optical integrators having different emission angles and the center of each optical integrator with respect to the optical axis of the irradiation unit. And a switching mechanism for selectively positioning and arranging.
In the divided sequential proximity exposure method according to claim 3, a mask smaller than the substrate as an exposure material is disposed close to and opposed to the substrate, and the substrate is stepped relative to the mask to move the mask. The mask pattern is opposed to a plurality of predetermined positions on the substrate, and the number of steps is set to 2 or more, and the substrate is irradiated with light for pattern exposure through the mask at each step. In a divided sequential proximity exposure method in which exposure is transferred onto the substrate,
The size of the mask and the number of steps are determined based on the relationship between the resist sensitivities and the exposure illuminance at which the allowable deflection amount of the mask, the size of the pattern area of the mask and the tact time are shortest and the required exposure accuracy is obtained. Further, an irradiation area in the step direction of the exposure light is set according to the exposure condition at the set step count.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partially exploded perspective view for explaining a divided sequential proximity exposure apparatus according to a first embodiment of the present invention, FIG. 2 is an enlarged perspective view of a mask stage portion, and FIG. 2 is a cross-sectional view taken along line III-III in FIG. 2, FIG. 3B is a plan view shown by arrow b in FIG. 4A, and FIG. 4 is a side view showing the basic structure of the alignment camera and the focus adjustment mechanism of the alignment camera. FIG. 5 is an explanatory diagram for explaining the irradiation optical system of the workpiece side alignment mark, FIG. 6 is a configuration diagram showing a focus adjustment mechanism of the alignment image, FIG. 7 is an explanatory diagram for explaining step exposure, and FIG. 9 is a plan view of a substrate W (1000 mm × 1200 mm) having nine chamfered materials DP for inch display, FIG. 9 is a view showing a mask disposed opposite to the substrate of FIG. 8, and (a) is a mask used in the case of three-step exposure. The top view of FIG. 10B is a plan view of a mask used in the case of two-step exposure, and FIG. 10 is arranged to face a substrate W (1000 mm × 1200 mm) obtained by chamfering a 12-inch 15-inch display material DP (long side direction 4 × short side direction 3). FIG. 11 is a graph showing the relationship between the vertical (long side) dimension of the mask and the maximum deflection due to its own weight when the horizontal (short side) dimension of the mask is constant, and FIG. 9A and 9B are graphs showing the relationship among the light source illuminance, the resist sensitivity, the number of steps, and the tact time when the masks of FIGS. 9A and 9B are used, and FIG. 13 is for the 4-step exposure not shown in FIG. FIG. 14 is a graph for explaining the irradiation region switching operation by the irradiation region switching means, and FIG. 15 is a diagram illustrating the relationship between the light source illuminance, the resist sensitivity, the number of steps, and the tact time when a mask is used. seed FIG. 16 is a perspective view for explaining an example of the switching mechanism of the irradiation region switching means, FIG. 17 is a perspective view for explaining a modification of the switching mechanism, and FIGS. It is explanatory drawing for demonstrating the division | segmentation successive proximity exposure apparatus which is other embodiment of this invention.
[0011]
1 to 7, reference numeral 1 denotes a mask stage for holding a mask M, 2 denotes a work stage for holding a glass substrate (material to be exposed) W, and 3 denotes pattern exposure. An illumination optical system 4 as an irradiating means is an apparatus base for supporting the mask stage 1 and the work stage 2, and a glass substrate W (hereinafter simply referred to as a substrate W) is disposed to face the mask M so as to face the mask M. A photosensitive agent is applied to the surface (opposite surface of the mask M) in order to transfer the mask pattern P drawn in (1).
[0012]
For convenience of explanation, the illumination optical system 3 will be described. The illumination optical system 3 includes, for example, a high-pressure mercury lamp 31 that is a light source for ultraviolet irradiation, and a concave mirror 32 that collects light emitted from the high-pressure mercury lamp 31. Two types of optical integrators 33a and 33b arranged so as to be switchable in the vicinity of the focal point of the concave mirror 32, plane mirrors 35 and 36, and a curved mirror 37 that guides a light beam incident through the plane mirrors 35 and 36 to the exposure surface as a parallel light beam, An exposure control shutter 34 is provided between the flat mirror 36 and the optical integrators 33a and 33b and controls the opening and closing of the irradiation light path.
[0013]
When the exposure control shutter 34 is controlled to be opened at the time of exposure, the light emitted from the high-pressure mercury lamp 31 is held on the mask M held on the mask stage 1 and on the work stage 2 via the optical path L shown in FIG. Irradiated as parallel light for pattern exposure perpendicularly to the surface of the substrate W (not shown in FIG. 1) so that the mask pattern P of the mask M is exposed and transferred onto the substrate W. It has become.
[0014]
Next, the mask stage 1 and the work stage 2 will be described in this order.
The mask stage 1 includes a mask stage base 11, and the mask stage base 11 is supported by a mask stage support 12 protruding from the apparatus base 4 and is disposed above the work stage.
As shown in FIG. 2, the mask stage base 11 has a rectangular shape and has an opening 111 at the center. A mask holding frame 13 is mounted on the opening 111 so as to be movable in the X and Y directions. Yes.
[0015]
As shown in FIG. 3A, the mask holding frame 13 is inserted between the inner periphery of the opening 111 of the mask stage base 11 through a predetermined gap, and a flange 131 is provided on the outer periphery of the upper end thereof. A flange 132 is fixed to the lower end surface so as to protrude outwardly, and is attached so as to be movable in the X and Y directions by the gap so that the thickness of the mask stage base 11 is vertically sandwiched between the flanges 131 and 132. ing. A mask M on which a mask pattern P is drawn is detachably held inside a flange 132 on the lower end surface of the mask holding frame 13 via a vacuum suction device (not shown). In such a holding state, since the lower surface of the mask M is located below the lower surface of the mask stage base 11, when the work stage 2 is moved in the Y-axis direction, the work stage 2 must be retracted in the Z-axis direction to a minimum. Limit.
[0016]
Further, on the upper surface of the mask stage base 11, mask position adjusting means 14 for adjusting the position of the mask M held on the mask holding frame 13 relative to the substrate W by moving the mask holding frame 13 in the X and Y planes. The mask position adjusting means 14 is provided, and is attached to one side of the mask holding frame 13 along the X-axis direction and the X-axis direction driving device 14x attached to one side of the mask holding frame 13 along the Y-axis direction. And two Y-axis direction drive devices 14y.
[0017]
The X-axis direction drive device 14x includes a drive actuator (for example, an electric actuator) 141 having a rod 141r extending and contracting in the X-axis direction, and a linear guide (linear motion) attached to a side portion of the mask holding frame 13 along the Y-axis direction. Bearing guide) 143, the guide rail 143r of the linear guide 143 extends in the Y-axis direction and is fixed to the mask holding frame 13, and a slider 143s attached to the guide rail 143r is movably attached to the rod 141r. It is connected to the tip via a pin support mechanism 142.
[0018]
On the other hand, the Y-axis direction drive device 14y includes a drive actuator (for example, an electric actuator) 141 having a rod 141r that expands and contracts in the Y-axis direction, and a linear guide attached to a side portion of the mask holding frame 13 along the X-axis direction ( Linear guide 143), the guide rail 143r of the linear guide 143 extends in the X-axis direction and is fixed to the mask holding frame 13, and the slider 143s movably attached to the guide rail 143r is a rod. It is connected to the tip of 141r via a pin support mechanism 142. The X-axis direction driving device 14x adjusts the mask holding frame 13 in the X-axis direction, and the two Y-axis direction driving devices 14y adjust the mask holding frame 13 in the Y-axis direction and θ-axis direction (oscillation around the Z-axis). ).
[0019]
On the inner side of the two sides of the mask holding frame 13 facing each other in the X-axis direction, a gap sensor 15 as a means for measuring a gap between the opposing surfaces of the mask M and the substrate W, and a plane of the mask M and the substrate W An alignment camera 16 as means for detecting the amount of deviation is provided, and both the gap sensor 15 and the alignment camera 16 are movable in the X-axis direction via a moving mechanism 17.
[0020]
The moving mechanism 17 has a holding frame 171 for holding the gap sensor 15 and the alignment camera 16 extending in the Y-axis direction on the upper surfaces of the two sides facing each other in the X-axis direction of the mask holding frame 13. The end of the holding base 171 on the side away from the Y-axis direction drive device 14 y is supported by a linear guide 172. The linear guide 172 includes a guide rail 172r installed on the mask stage base 11 and extending along the X-axis direction, and a slider (not shown) that moves on the guide rail 172r. The end of the holding frame 171 is fixed.
[0021]
Then, the gap sensor 15 and the alignment camera 16 are moved in the X-axis direction via the holding base 171 by driving the slider by a driving actuator 173 including a motor and a ball screw.
A masking aperture (shielding plate) 18 that shields both ends of the mask M as necessary is disposed at both ends in the Y-axis direction of the opening 111 of the mask stage base 11 so as to be positioned above the mask M. The masking aperture 18 can be moved in the Y-axis direction by a masking aperture driving device 181 including a motor, a ball screw, and a linear guide so that the shielding areas at both ends of the mask M can be adjusted.
[0022]
The work stage 2 is installed on the apparatus base 4, and a Z-axis feed base (gap adjusting means) 6 that adjusts a gap between the opposing surfaces of the mask M and the substrate W to a predetermined amount, and the Z-axis feed base 6 and a work stage feed mechanism 7 that moves the work stage 2 in the Y-axis direction.
The Z-axis feed base 6 includes a Z-axis coarse movement stage 62 that is supported by a vertical coarse movement device 61 erected on the apparatus base 4 so as to be capable of coarse movement in the Z-axis direction, and an upper portion of the Z-axis coarse movement stage 62. And a Z-axis fine movement stage 64 supported via an up / down fine movement device 63. For example, a pneumatic cylinder is used as the vertical movement device 61. By performing a simple vertical movement, the Z-axis coarse movement stage 62 is moved up and down without measuring the gap between the mask M and the substrate W to a preset position. Let
[0023]
On the other hand, the vertical fine movement device 63 includes a movable wedge mechanism formed by combining a motor, a ball screw, and a wedge. In this embodiment, for example, a ball screw is driven by a motor 631 installed on the upper surface of the Z-axis coarse movement stage 62. The screw shaft 632 is driven to rotate, and the ball screw nut 633 is formed in a wedge shape, and the inclined surface of the wedge nut 633 is engaged with the inclined surface of the wedge 641 protruding from the lower surface of the Z-axis fine movement stage 64. This constitutes a movable wedge mechanism.
[0024]
When the screw shaft 632 of the ball screw is rotationally driven, the wedge-shaped nut 633 is finely moved in the Y-axis direction, and this horizontal fine movement is converted into a highly accurate vertical fine movement by the slope action of the wedges 633 and 641. The
The vertical fine movement device 63 composed of this movable wedge mechanism is installed in two units on one end side (front side in FIG. 1) in the Y-axis direction of the Z-axis fine movement stage 64, and one unit on the other end side. In this way, the vertical fine movement device 63 adds to the function of finely adjusting the height of the Z-axis fine movement stage 64 to the target value while measuring the gap between the mask M and the substrate W. Thus, it also has a tilt function for finely adjusting the inclination with respect to the horizontal plane.
[0025]
The work stage feed mechanism 7 includes two sets of linear guides 71 that are spaced apart from each other in the X-axis direction on the upper surface of the Z-axis fine movement stage 64 and extend along the Y-axis direction, and a slider ( (Not shown)) and a Y-axis feed drive device 73 for moving the Y-axis feed stand 72 in the Y-axis direction. The motor 731 of the Y-axis feed drive device 73 A Y-axis feed base 72 is connected to a ball screw nut (not shown) screwed to a ball screw shaft 732 that is driven to rotate.
[0026]
The work stage 2 is mounted on the Y-axis feed base 72, and mirrors 741 of laser interferometers 743 and 744 as feed error detecting means 74 for detecting the Y-axis feed error of the work stage 2. , 742 are installed. The mirror 741 extends along the Y-axis direction on one side in the width direction of the Y-axis feed base 72, and the mirrors 742 are spaced apart from each other in the X-axis direction on one end side in the Y-axis direction of the Y-axis feed base 72. Are arranged.
[0027]
The feed error detecting means 74 is arranged so as to face the mirror 741 and supported by the apparatus base 4. The laser interferometer 743 for straightness detection and the two mirrors 742 are arranged opposite to each other and supported by the apparatus base 4. And a laser interferometer 744 for detecting the tilt of the table and the distance in the Y-axis direction. Work stage 2 generated at the stage of sending the substrate W to the next area when the exposure is performed by connecting the second divided pattern following the exposure of the Y-axis feed base 72 and the first divided pattern from the laser interferometers 743 and 744. The feed error is detected and the detection signal is output to a correction control means (not shown). The correction control means calculates a positioning correction amount for joint exposure based on this detection signal, and outputs the calculation result to the drive circuit of the mask position adjusting means 14 (and the vertical fine movement device 63 as necessary) As a result, the mask position adjusting means 14 and the like are driven according to the correction amount to correct the positional deviation.
[0028]
Next, the feed error of the work stage 2 will be described. As a feed error when the work stage 2 is fed by a predetermined distance in the Y-axis direction, in addition to the feed position (distance) error, the straightness and the work stage surface There is a tilt.
Straightness is the amount of deviation (in the XZ plane) at the feed end point between the Y axis passing through the feed start point and the actual straight line in the feed direction, and the X axis direction component ΔX and the Z axis direction component ΔZ Consists of. On the other hand, the tilt of the work stage surface is caused by yawing (rotation around the Z axis), pitching (rotation around the X axis), rolling (rotation around the Y axis), etc., when the work stage 2 is moved. In yawing, the work stage surface is swung to the left or right while it is horizontal and shifted by an angle θ with respect to the Y axis. In pitching, the work stage surface is tilted by a predetermined angle before and after the direction of travel. In rolling, the work stage surface Is inclined at a predetermined angle to the left and right with respect to the horizontal. These errors occur due to, for example, the accuracy of a linear guide that is a linear motion bearing guide device.
[0029]
Among the feed errors, the feed error detecting means 74 can know the yawing and the straightness X-axis direction component ΔX. That is, yawing can be detected from the difference between the measured values of the two laser interferometers 744 and 744 in the Y-axis direction, and the straightness can be obtained from the result and the laser interferometer 743 in the X direction. Further, the error in the Y-axis direction position can be obtained from the average value of the two laser interferometers 744 and 744 in the Y-axis direction. In addition, the straightness Z-axis direction component ΔZ, pitching, and rolling can be known by the three gap sensors 15.
[0030]
By the way, in the case of performing division sequential exposure, even if there is no feed error of the work stage 2, if the orientation of the mask pattern P of the mask M is deviated from the feed direction of the work stage 2 (Y-axis direction), The joints of the patterns dividedly formed on the substrate W by the joining exposure are shifted and are not aligned. In addition, as described above, the mask M is sucked and held on the lower surface of the mask holding frame 13 via the vacuum suction device. When sucking and holding the mask M, the orientation of the mask pattern P of the mask M and the work stage feed mechanism 7 are maintained. It is difficult to accurately match the moving direction (Y-axis direction) of the work stage 2 by.
[0031]
Therefore, in this embodiment, as shown in FIG. 7, at least two places on the upper surface of the work stage 2 (actually a work chuck installed on the work stage 2), for example, a work side having a cross shape The alignment marks 75 are formed apart from each other in the X-axis direction, while the mask side alignment mark 76 corresponding to the workpiece side alignment mark 75 is formed on the mask M.
[0032]
Then, by adjusting the position of the mask holding frame 13 by the X-axis direction driving device 14x and the Y-axis direction driving device 14y, the centers of the workpiece side alignment mark 75 and the mask side alignment mark 76 are substantially within the XY plane. To match and match.
Next, a description will be given of increasing the accuracy of alignment between patterns formed by divisional exposure in the first layer.
[0033]
In this embodiment, the mirror 741 defines the straightness reference in the Y-axis direction with the Y-axis direction being a direction parallel to the reflecting surface of the mirror 741 for the laser interferometer 743 in the X-axis direction. When the workpiece-side alignment mark 75 and the mask-side alignment mark 76 are aligned, the orientation of the mask pattern P of the mask M is in the Y-axis direction, in other words, relative to the direction parallel to the reflecting surface of the mirror 741. It is set so that there is no inclination. For this reason, a line connecting the centers of the two mask-side alignment marks 76 and a direction to be coincident with the Y-axis direction (the direction of the mask pattern P: the direction of the short side in the case of the rectangular pattern P in FIG. 7) Is made equal to the angle formed between the line connecting the centers of the two workpiece side alignment marks 75 and the reflecting surface of the mirror 741.
[0034]
In this embodiment, the reflection surface of the mirror 741 for the laser interferometer 743 in the X-axis direction is strictly orthogonal to the line connecting the centers of the two work-side alignment marks 75 on the work stage 2. The relationship between the line connecting the centers of the two mask-side alignment marks 76 and the orientation of the mask pattern P is the same. Then, alignment with the mask M is performed using the workpiece side alignment mark 75 as a reference, and the first step exposure is performed.
[0035]
The alignment between the workpiece side alignment mark 75 and the mask side alignment mark 76 can be easily performed with high accuracy by the alignment camera 16 which is an alignment mark detection means.
As shown in FIG. 4, the alignment camera 16 optically detects a mask mark 76 on the front surface of the mask M held on the lower surface of the mask stage 1 from the back surface side of the mask. The focus is adjusted by moving toward and away from M.
[0036]
The focus adjustment mechanism 161 includes a linear guide 162, a ball screw 163, and a motor 164. A guide rail 162r of the linear guide 162 is attached to the holding frame 171 of the moving mechanism 17 of the mask stage 1 so as to extend vertically. An alignment camera 161 is fixed to a slider 162s of the guide 162 via a table 162t. The nut screwed to the screw shaft of the ball screw 163 is connected to the table 162t, and the screw shaft is driven to rotate by the motor 164.
[0037]
Further, in this embodiment, as shown in FIG. 5, a work side alignment mark 75 is projected from below with a light source 781 and a condenser lens 782 below the work chuck 8 provided on the work stage 2. A projection optical system 78 is disposed integrally with the Z-axis fine movement stage 64 in accordance with the optical axis of the alignment camera 16. A through hole corresponding to the optical path of the projection optical system 78 is formed in the work stage 2 and the Y-axis feed base 72.
[0038]
Further, in this embodiment, as shown in FIG. 6, the best alignment image for detecting the position of the surface (mask mark surface Mm) having the mask side alignment mark 76 of the mask M and preventing the alignment camera 16 from being out of focus. A focus adjustment mechanism 9 is provided.
This best focus adjustment mechanism 9 uses a gap sensor 15 as a focus deviation detection means in addition to the alignment camera 16 and the focus adjustment mechanism 161, and the measured value of the mask lower surface position measured by the gap sensor 15 is calculated by a computer. A difference is obtained by comparing with a preset focus position in 92, a relative focus position change amount from the set focus position is calculated from the difference, and the motor 164 of the focus adjustment mechanism 161 is controlled in accordance with the calculated change amount. The alignment camera 16 is moved so that the focus of the alignment camera 16 is adjusted.
[0039]
By using this best focus adjustment mechanism 9, it is possible to perform high-precision focus adjustment of the alignment image regardless of the change in the plate thickness of the mask M and the variation in the plate thickness. The focus adjustment mechanism 161, the projection optical system 78, the best focus adjustment mechanism 9 and the like not only correspond to the high accuracy of the alignment of the first layer divided pattern, but also the high accuracy of the alignment after the second layer. If the thickness of the mask M is known, the best focus adjustment mechanism 9 may be omitted and the focus adjustment mechanism may be moved according to the thickness.
[0040]
Here, in this embodiment, the size of the mask M on which the mask pattern P is drawn and the number of steps of the substrate W (work stage 2) when performing step exposure are determined as follows.
First, the size of the mask M is determined from the amount of deflection of the mask M and the exposure accuracy to be obtained.
[0041]
That is, the dimension in the step direction (Y-axis direction dimension) of the mask M is selected so that the maximum value δmax of the deflection due to the weight of the mask M is within the allowable value. Note that the width dimension (X-axis direction dimension) of the mask M is constant. Further, the calculation of the maximum deflection value δmax differs depending on how the mask M is held on the mask stage 1 (4 side constraint, 4 side support, or intermediate between them). In this embodiment, the mask M is limited to 4 sides. The following equation (1) shows a calculation example of the maximum deflection value δmax of a rectangular plate that receives a vertical equally distributed load when four sides are constrained.
[0042]
δmax = α × P × a^Four/ (E × t^Three(1)
However,
α: Maximum deflection coefficient (a value determined by the aspect ratio of the fixed side of the rectangle. When the aspect ratio of the mask is 1.25, α is 0.020. This value is almost constant even if the aspect ratio changes slightly. (It may be set to α = 0.020 because it does not change.)
P: Uniform load (= W / S)
W: Weight (= V × ρ = a × b × t × ρ)
V: Volume
ρ: Material density (quartz 2.2 g / cm^Three)
a: Step size
b: Width dimension (x-axis direction dimension)
t: thickness
E: Longitudinal elastic modulus coefficient (quartz 7413kg / mm²)
11 and Table 1 show calculation results of the maximum deflection value δmax of the mask M when the thickness t of the mask M is 8 mm and the step direction dimension a is 500 to 1200 mm (eight types for every 100 mm). Then, a mask M having a step direction dimension a in which the maximum deflection value δmax is less than or equal to the allowable value is selected.
[0043]
[Table 1]

[0044]
In this embodiment, as the substrate W, a substrate W of 1000 mm × 1200 mm shown in FIG. 8 is used for chamfering the 18-inch display material DP, and a substrate W having the same size as that of FIG. A 12-inch chamfered material for a 15-inch display DP (step direction 4 × width direction 3) is used.
The mask M used for the substrate W on which the 18-inch display material DP shown in FIG. 8 is chamfered and the size of the pattern area of the mask M are three in the width direction of the substrate W as shown in FIG. 1100 mm × 700 mm (step direction dimension a) on which the mask pattern P (corresponding to the 18-inch display material DP) is drawn, or three in the width direction of the substrate W as shown in FIG. 1100 mm × 900 mm (step direction dimension a) in which the mask pattern P is arranged in two rows (6 in total) in the step direction of the substrate W is considered. In the former, the number of steps of the substrate W is 3 times (the first time) The exposure position is one step.) In the latter, the number of steps of the substrate W is two.
[0045]
Here, if the allowable value of the maximum deflection value δmax is 60 μm in consideration of the exposure accuracy and the like, from FIG. 11 and Table 1, the mask M in FIG. The mask M in FIG. 9A having a dimension a of 700 mm is selected.
On the other hand, the size of the mask M used for the substrate W on which the 15-inch display material DP is chamfered 12 and the pattern area of the mask M are not shown, but three mask patterns P (15 in the width direction of the substrate W are omitted). 10 corresponding to the inch display material DP) and three mask patterns P drawn in the width direction of the substrate W in two rows in the step direction of the substrate W as shown in FIG. Arranged 1100 mm × 700 mm (step direction dimension a) or three mask patterns P drawn in the width direction of the substrate W are arranged in three rows (9 in total) in the step direction of the substrate W although illustration is omitted. In the former case, the number of steps of the substrate W is four times (the first exposure position is one step), and in the latter two cases, the number of steps of the substrate W is two times.
[0046]
Here, if the allowable value of the maximum deflection value δmax is 60 μm in consideration of exposure accuracy and the like as described above, a mask in which nine mask patterns P having a step direction dimension a exceeding 900 mm are drawn from FIG. 11 and Table 1. M cannot be applied, and two types of masks M, in which the number of steps is 4 and the mask in FIG. 10 in which the number of steps is 2, are selected.
[0047]
In this embodiment, as shown in FIG. 10, the dimension of the mask M in which three mask patterns P drawn in the width direction of the substrate W are arranged in two rows (6 in total) in the step direction of the substrate W. Is set to 1100 mm × 700 mm (step direction dimension a), so that the size of the substrate W and the mask M is the same in the case of nine chamfering of the 18-inch display material DP and the case of twelve chamfering of the 15-inch display material DP. can do.
[0048]
Next, with respect to the size of the selected mask M and the number of steps of the substrate W, exposure illuminance and resist (photosensitive agent applied to the substrate) are set as exposure conditions that provide the shortest tact time and the required exposure accuracy. ) Select based on sensitivity.
First, how to obtain the tact time will be described.
Substrate loading / unloading time A (sec / cycle) = const, proximity gap control time and pattern alignment control time B (sec / step) = const, work table moving time at step C (sec / step) , Tact time T when the number of steps is n where exposure time is D (sec / step) and the number of steps of substrate W is n_nIs obtained by the following equation (2). A and B are constant values regardless of the number of steps, and C and D vary depending on the number of steps. Accordingly, in the following, those that differ depending on the number of steps will be indicated with a suffix.
[0049]
T_n= A + B + D_n+ C_n+ B + D_n+ C_n+ …… + D_n
= A + B + D_n+ (N-1) (C_n+ B + D_n(2)
Further, the work table moving time C at the time of the step is obtained by the following equation (3).
C = 2v / α_w+ (X−v 2 / α_w) / V = v / α_w+ X / v (3)
However,
v: Work table moving speed (const)
α_w: Work table acceleration / deceleration value (const)
x: Step amount (varies depending on the number of steps)
Next, the tact time T when the mask M (the number of steps n = 3) in FIG. 9A is used._nIs the tact time T when the mask M (step number n = 2) in FIG. 9B is used._nA shorter condition is obtained by the following equation (4). Note that the step amount x of the substrate W when the number of steps n = 3._ThreeIs the step amount x of the substrate W when the number of steps n = 2.₂Is 754 mm.
[0050]
△ T_n= T_Three-T₂
= (2C_Three-C₂) + (3D_Three-2D₂) + B
= V / α_w+ 1 / v (2x_Three-X₂) + 3D_Three-2D₂+ B
= 3D_Three-2D₂+ V / α_w+ B (4)
Where △ T_n= 3D_Three-2D₂+ V / α_w+ B <0, ie D₂> 3 / 2D_Three+ V / 2α_wIf the relationship of + B / 2 is satisfied, the tact time T of the mask M in which the number of steps of the substrate W is n = 3 is greater than that of the mask M in which the number of steps of the substrate W is n = 2_nWill be faster.
[0051]
Using the equation (4), the mask M in which the number of steps n = 2 is the tact time T._nBecomes faster (△ T_n> 0) and the mask M with the number of steps n = 3 is tact time T_nBecomes faster (△ T_nThe result of calculating | requiring the relationship between the light source illumination intensity in the case of <0) and a resist sensitivity by calculation is shown in FIG. The proximity gap control time and the pattern alignment control time B are 7 sec, the work table moving speed v is 350 mm / sec, the work table acceleration / deceleration value α._w1400mm / sec²As calculated.
[0052]
As the mask M used for the substrate W on which the 18-inch display material DP shown in FIG. 8 is chamfered, the mask M (the step direction dimension a is 700 mm) in FIG. Therefore, a combination of as large an illuminance and resist sensitivity as possible is selected within the advantageous area of the three steps of FIG. If the illuminance and resist sensitivity are determined, the corresponding exposure time (D in equation (4))₂, D_Three) Is determined. As a result, despite the large number of steps, the tact time T_nCan be made shorter than in the case of two steps.
[0053]
On the other hand, as the mask M used for the substrate W for chamfering the 12-inch 15-inch display material DP, two types of masks M having four steps and mask M in FIG. 10 having two steps are selected. However, as described above, the relationship between the light source illuminance, the resist sensitivity, the number of steps, and the tact time was obtained by calculation using the equation (4). As shown in FIG. 13, the number of steps was 2 regardless of the illuminance. It has been found that the mask M shown in FIG. 10 is always more advantageous than the mask M having four steps. Therefore, the mask M in FIG. 10 is selected in which the number of steps is two.
[0054]
Next, according to the size (step direction) of the area to be exposed on the mask M for each of the mask M in which the number of steps n = 3 in FIG. 9A and the mask M in which the number of steps n = 2 in FIG. Then, an optical integrator that secures an irradiation region S (indicated by a two-dot chain line in FIGS. 9 and 10) for step exposure and increases illuminance is selected. Then, as shown in FIG. 1, the two selected optical integrators 33a and 33b are arranged near the focal point of the concave mirror 32 of the illumination optical system 3, and the irradiation area switching means 200A is used according to the type of the mask M. Exposure is performed by switching between them.
[0055]
The irradiation area S is set to 1000 mm × 400 mm (step direction dimension) in the case of the mask M in FIG. 9A, and 1000 mm × 600 mm (step direction dimension) in the case of the mask M in FIG. Further, the two types of optical integrators 33a and 33b have such a relationship that the irradiation region only in the step direction (Y-axis direction) changes, and therefore the irradiation region in the X-axis direction is constant.
[0056]
As shown in FIG. 15, the curvature radius R1 of the lens surface of one of the optical integrators 33a and 33b is larger than the curvature radius R2 of the lens surface of the other optical integrator 33b (R1>). R2), the emission angle of the optical integrator 33a is larger than the emission angle of the optical integrator 33b. Therefore, the irradiation region S in the step direction (Y-axis direction) when the optical integrator 33a is used._y1Is an irradiation region S in the step direction (Y-axis direction) when the optical integrator 33b is used._y2The former corresponds to the mask M in which the number of steps in FIG. 10 is two, and the latter corresponds to the mask M in which the number of steps n = 3 in FIG. 9A.
[0057]
The irradiation means switching means 200 </ b> A includes two types of optical integrators 33 a and 33 b and a switching mechanism 200.
As shown in FIG. 16, the switching mechanism 200 includes a replacement stage 202 to which two types of optical integrators 33a and 33b are fixed via support portions 201a and 201b, respectively. The replacement stage 202 is a guide rail. The linear guide 205 including the slider 203 and the slider 204 is fixed to the slider 204 and is movable along the guide rail 203 together with the slider 204.
[0058]
A handle 206 is provided at one end in the moving direction of the replacement stage 202, and the center of the optical integrator 33 a or the optical integrator 33 b coincides with the optical axis L of the illumination optical system 3 by pushing and pulling the handle 206. Are positioned as follows.
In the case of the mask M in which the number of steps n = 2 in FIG. 10, the center of the optical integrator 33a having a large emission angle is positioned on the optical axis L of the illumination optical system 3, and exposure is performed in this state. As shown in FIG. 14A, the irradiation region S wide in the step direction._y1In the case of the mask M in which the number of steps n = 3 in FIG. 9A is obtained, the center of the optical integrator 33b on the side with a smaller exit angle is positioned on the optical axis L of the illumination optical system 3, and this state As shown in FIG. 14 (b), the irradiation area S narrow in the step direction is obtained by performing exposure with_y2Is obtained.
[0059]
In this embodiment, a fly-eye lens is used as the optical integrators 33a and 33b to switch the entire fly-eye lens. Instead, a combination lens or fly-eye is used as the optical integrators 33a and 33b. Only a part of the lenses may be switched using a combination of a lens and a combined lens.
[0060]
FIG. 17 shows a modification of the switching mechanism.
The switching mechanism 300 is fixed to a rotating holder 301 that holds four types of optical integrators 33a to 33d having different emission angles and a main body (not shown) of the illumination optical system 3, and rotates the rotating holder 15 by a predetermined angle. And a rotation drive motor 302 that positions each optical integrator 33a to 33d so as to coincide with the optical axis L of the illumination optical system 3 in accordance with the change of the mask size. Three or more types of masks M are used. It is effective in the case.
[0061]
Next, the operation of the divided sequential proximity exposure apparatus having the above configuration will be described.
For example, when a predetermined pattern is formed on an RGB color filter for a color filter type large-sized liquid crystal display, a black matrix pattern for partitioning pixels is first applied on a glass substrate W, and then an oxygen blocking film is applied. , Exposure and development steps. On the substrate W on which the black matrix pattern is formed in this manner, the same process as the pattern formation of the black matrix is performed for each of the three primary colors R (red), G (green), and B (blue) for each color. Repeat and form. Here, the first black matrix pattern to be formed on the substrate W is “first layer”, one of the three primary colors formed on the first layer is “second layer”, and the other one of the three primary colors to be formed next These patterns are called “third layer”, and the remaining three primary color patterns to be formed next are called “fourth layer”.
[0062]
Here, in the case of the first step exposure, the number of steps is set to n = 3 on the substrate W on which the 18-inch display material DP shown in FIG. 8 is chamfered, and the mask M of FIG. 9A is used as a mask. Then, a black matrix pattern of the first layer is formed on a glass substrate W of a color filter for a large-sized liquid crystal display by three-division sequential proximity exposure.
[0063]
On the lower surface of the mask stage 1 of the division sequential proximity exposure apparatus, a mask M on which a first-layer pattern is drawn is mounted in advance by vacuum suction. Further, the work stage 2 is positioned in the vicinity of the forward limit in the Y-axis direction and is lowered to the lowest limit in the Z-axis direction.
(1) Gap adjustment for alignment
First, a coarse movement upper limit target position (for example, a position on the order of several mm from the surface of the mask M) in which the work stage 2 is preset by driving the vertical coarse movement device 61 of the Z-axis feed base 6 constituting the gap adjusting means 6. ). During this coarse movement, the gap sensor 15 does not measure the gap (gap) between the upper surface of the work chuck 8 (actually, the upper surface of the glass test portion 8m fixed thereon) and the mask M.
[0064]
Next, the three vertical movement devices 63 of the Z-axis feed base 6 are driven to raise the work stage 2 by fine movement by the wedge action, thereby bringing the work stage 2 and the mask M close to each other. At the time of this fine movement, as shown in FIG. 5, the gap sensor 15 measures the gap between the surface of the mask M having the mask side alignment mark 76 and the surface of the work chuck 8 having the work side alignment mark 75. The measurement result is output to a control device (not shown) of the vertical fine motion device 63, which controls the vertical fine motion device 63 so as to coincide with a preset target gap amount at the time of alignment. Raise 2
[0065]
In this way, the vertical movement speed of the gap adjusting means 6 is divided into two speeds, and most of the ascending distance of the work stage 2 is raised at a high speed by the vertical coarse movement device 61 and finally by the vertical fine movement device 63. Since the work stage 2 is slightly moved and raised with high accuracy, it is possible to simultaneously achieve high speed and high accuracy of the gap adjustment work in the divided sequential proximity exposure.
(2) Alignment adjustment
Thus, when the work stage 2 and the mask M are brought close to each other, when the relative position and posture of the substrate W in the step direction (Y-axis direction) and the mask M are not correctly aligned, for example, FIG. As shown to (a), when the mask M which has the mask pattern P inclines by the angle (theta) with respect to the work stage 2 (assuming that the direction of the work stage 2 and the direction of a Y-axis direction correspond) In this case, the workpiece side alignment mark 75 and the mask side alignment mark 76 are not aligned and are displaced. Accordingly, if the exposure and transfer of the mask pattern P in the first step is performed as it is, a deviation from the divided pattern P formed on the same substrate W occurs in the next step, and a highly accurate black matrix pattern is obtained. Absent.
[0066]
Therefore, alignment work (alignment) between the workpiece side alignment mark 75 and the mask side alignment mark 76 is performed using the alignment camera 16, and at this time, the focus adjustment mechanism 161 focuses both the marks 75 and 76.
In the first step exposure, referring to FIG. 5, at the time of alignment, the work side alignment mark 75 is irradiated from below by the projection optical system 78, and the work side alignment is performed using the gap sensor 15 used at the time of exposure. By setting a gap between the surface (test portion) 8m of the work chuck 8 having the mark 75 and the surface of the mask M having the mask side alignment mark 76 (mask mark surface Mm), both marks 75 and 76 are provided. The alignment camera 16 is substantially brought into focus and the shift between the marks 75 and 76 is detected.
[0067]
In general, the thickness of the mask M is standardized to 5 mm, 8 mm, 10 mm, etc., so it is possible to respond quickly to changes or variations in the mask thickness with a single fixed focus like a conventional alignment camera. However, in this embodiment, the focus position of the alignment camera 16 corresponding to various mask plate thicknesses is set in advance in the focus adjustment mechanism 161. The focus of the alignment camera 16 can be positioned on the mask mark surface Mm which is the best focus position in response to a large change in the mask thickness due to the replacement of the mask M.
[0068]
Further, in order to detect the focus shift, the gap sensor 15 measures the actual mask lower limit position, and outputs the measured value to the computer 92 to set the focus position (mask mark surface Mm) previously set on the mask lower surface (mask mark surface Mm). Since the relative focus position change amount from the target position) is calculated and the focus adjustment mechanism 161 is operated by that amount to correct the position of the alignment camera 16, for example, the mask is adjusted by adjusting the focus deviation due to the mask thickness variation. The best focus for the mark 76 can be guaranteed.
[0069]
When a deviation is detected between the workpiece side alignment mark 75 and the mask side alignment mark 76 by the alignment camera 16 with the focus adjusted properly (FIG. 7A), the detected signal is used as a mask position adjusting means. 14 control device (not shown), and the control device controls the driving of the X-direction drive device 14x and the two Y-direction drive devices 14y, thereby correcting the posture of the mask holding frame 13 The marks 75 and 76 are aligned as shown in FIG. Thus, the inclination θ between the mask M and the Y-axis direction (in the figure, the long-side direction and Y-axis direction of the substrate W, the short-side direction of the mask M, and the short-side direction of the mask pattern P are parallel to each other). Is resolved).
(3) Inserting the substrate W and exposing the first step
After the alignment is completed, the work stage 2 is once lowered as necessary by the gap adjusting means 6. In this state, the substrate W is loaded onto the work stage 2 by an automatic work supply device (not shown) using the distance between the work stage 2 and the mask stage 1 (for example, about 60 mm). Hold on the upper work chuck 8. Thereafter, the gap adjusting means 6 again adjusts the gap between the lower surface of the mask M and the upper surface of the workpiece W so as to be a predetermined value necessary for exposure. The procedure is the same as the procedure (1) except that the gap sensor 15 measures the gap between the lower surface of the mask M and the upper surface of the substrate W.
[0070]
When the work stage 2 is moved up and down by the gap adjusting means 6, the work stage 2 may move slightly even in the XY plane. For such a case, the position data obtained by the laser interferometers 743, 744, and 744 after completion of the alignment in (2) is stored by the correction control means, and the position data after gap adjustment is stored. If the data has changed, the mask position adjusting means 14 corrects the change by the amount of change, thereby returning the mask M to the state in which there is no inclination between the direction of the mask M and the Y-axis direction.
[0071]
Next, the switching mechanism 200 is operated to position the center of the optical integrator 33b on the side with a small emission angle on the optical axis L of the illumination optical system 3, and in this state, the exposure control shutter 34 of the illumination optical system 3 is controlled to open. Then, the first step exposure is performed, and the mask pattern P of the mask M is baked onto a predetermined position of the substrate W to obtain the first divided pattern P1 on the substrate W.
(4) Movement of the work stage 2 to the exposure position of the second step
Subsequently, in order to perform joint exposure of the second divided pattern P2, the work stage 2 is moved with respect to the mask M by driving the feed drive device 73 of the work stage feed mechanism 7 to move the work stage 2. 7 (b) is sent by one step amount in the arrow Y direction, and the substrate W is placed at the exposure position of the second step. At this time, in order to avoid interference between the substrate W and the mask M, the work stage 2 may be lowered in the Z-axis direction by a necessary amount.
(5) Alignment adjustment due to work stage 2 feed error
As described above, when the work stage 2 is sent by one step amount in the direction of arrow Y in FIG. 7B with respect to the mask M, a feed error due to the above-mentioned factors occurs. As a result, the second divided pattern P2 is slightly displaced. For example, due to the yawing and straightness errors of the work stage 2 during the step feed of the work stage 2, as shown in FIG. 7C, the straight line is deviated from the normal position by the straightness Δx and the inclination angle θ ′.
[0072]
Therefore, before the second divided pattern P2 is exposed and transferred onto the substrate W, the feed error of the substrate W is detected by the feed error detecting means 74, and the detection result is connected to the correction control means for correcting the exposure position. The correction control means calculates a positioning correction amount for joint exposure based on the detection result, and based on the calculation result, the mask position adjusting means 14 (and gap adjustment as necessary, such as pitching correction at the time of feeding). For this purpose, the X-axis direction drive device 14x and the Y-axis direction drive device 14y of the vertical fine movement device 63) are controlled to adjust the position of the mask holding frame 13 and to perform alignment adjustment for correcting the displacement of the mask M. In addition, when the gap adjustment between the mask M and the substrate W is performed by the gap adjusting unit 6, the alignment adjustment is performed based on the yawing and straightness data in the subsequent state.
(6) Second step exposure
Thereafter, the exposure control shutter 34 of the illumination optical system 3 is controlled to be opened to perform the second exposure, and the mask pattern P of the mask M is printed at a predetermined position on the substrate W to correct the positional deviation on the substrate W. A second division pattern P2 is obtained (see FIG. 7D).
(7) Third step exposure
As for the exposure of the third step, the movement of the work stage 2 to the exposure position of the second step, the alignment adjustment by the feed error of the work stage 2 and the third step are performed in the same manner as in the above (4), (5) and (6). Eye exposure is performed to obtain a third divided pattern P3 (not shown) whose positional deviation is corrected on the substrate W.
[0073]
As is clear from the above description, in this embodiment, the size of the mask M and the number of steps of the substrate W are selected from the deflection amount of the mask M, the exposure accuracy to be obtained, and the size of the pattern area of the mask M. In addition, for the size of the selected mask M and the number of steps of the substrate W, an exposure condition that provides the shortest tact time and provides the required exposure accuracy is selected based on the relationship between exposure illuminance and resist sensitivity. Further, for each selected mask M, an optical integrator that secures an irradiation area S for step exposure and increases the illuminance in accordance with the size (step direction) of the area to be exposed on the mask M is selected. Since exposure is performed, it is possible to perform high-accuracy and high-throughput on a substrate of a predetermined size in multi-planar exposure of flat panel displays. It is possible to step exposure.
[0074]
In the above embodiment, the case where the present invention is applied to the divided sequential proximity exposure apparatus provided with the feed error detecting means 74 such as the laser interferometers 743 and 744 is taken as an example. Of course, the present invention can also be applied to a divided sequential proximity exposure apparatus that does not include the error detection means 74.
In the above embodiment, the step exposure of the first layer is taken as an example. However, the present invention is not limited to this, and the present invention is also applied to a type in which positioning is performed only by alignment marks mainly including step exposure of the second layer and subsequent layers. May be applied.
[0075]
FIG. 18 is a diagram showing a second embodiment of the present invention. This is a modification of the structure related to the projection image formation of the alignment mark in the divided sequential proximity exposure apparatus of the present invention, particularly an optical system for projecting the workpiece side alignment mark 75 from below the work chuck onto the mask alignment mark surface. There is no redundant description of the same components as in the first embodiment. That is, in the projection optical system 78A of the present embodiment, the light source 781, the condenser lens 782, and the workpiece side alignment mark 75 are disposed below the workpiece chuck 8, and the imaging lens 783 is further above the workpiece side alignment mark 75. Is different from the projection optical system 78 of the first embodiment.
[0076]
By disposing the imaging lens 783 so that the workpiece side alignment mark 75 is positioned on one focal point and the mask mark surface Mm of the mask M is positioned on the other focal point, the workpiece side alignment mark 75 is arranged. Projection imaging can be performed at the same level as the mask side alignment mark 76.
According to the second embodiment, the workpiece side alignment mark 75 can be focused by optically matching the workpiece side alignment mark 75 from the outside onto the mask side alignment mark 76 from the outside during alignment. And the mask side alignment mark 76 are not defocused from the detection optical system at all, and an ideal pattern can be detected, so that it is possible to perform divided sequential proximity exposure of the first layer with higher accuracy. .
[0077]
FIG. 19 is a diagram showing a third embodiment of the present invention. This is a modified example of the best focus adjustment mechanism of the alignment image among the structures related to the projection image formation of the alignment mark in the divided sequential proximity exposure apparatus of the present invention, and is similar to the other first embodiment. A duplicate description of the components will be omitted.
That is, the best focus adjustment mechanism 9A for the alignment image according to the present embodiment includes the alignment camera 16, the focus adjustment mechanism 161, and the computer 92A, and the mask side alignment mark on the mask mark surface Mm of the mask M imaged by the alignment camera 16. The contrast of the image 76z of the 76 pattern is measured by the detection scanning line, and a state in which the wave heights D and D ′ of the differential waveform 77 of the image contrast are maximized is searched for while moving the camera 16 by the focus adjustment mechanism 161. As a result, there is an advantage that the camera position where the pattern image 76z appears most sharply can be obtained and alignment with higher accuracy can be realized. In addition, as in the second embodiment, there is no influence on the detection optical system with respect to any mask thickness and variations in mask thickness, and the effect that high-precision detection is possible for any mask thickness is possible. Is obtained.
[0078]
When the pattern exposure of the first layer (that is, the black matrix) is completed as described above, it is finished through a predetermined process such as development, and a process including pattern exposure of the second layer, the third layer, and so on. . Normally, color filters and the like are produced by line equipment, and the exposure apparatus is a dedicated apparatus for the first layer, the second layer, and so on.
[0079]
Of course, the exposure apparatus for the second and subsequent layers is provided with a mask position adjusting means using the apparatus of the present invention, that is, the workpiece side alignment mark 75 to detect and correct the workpiece stage feed error to perform continuous exposure. A divided sequential proximity exposure apparatus can be used. However, if the pattern of the mark used for alignment of the second and subsequent layers is included in the exposure pattern of the first layer, alignment is performed based on this mark formed on the workpiece during the exposure of the second and subsequent layers. In this case, the exposure apparatus for the second and subsequent layers may be a conventional exposure apparatus having a function of aligning the alignment mark on the workpiece and the alignment mark on the mask.
[0080]
However, in such a conventional exposure apparatus, a mechanism for high-precision alignment of the joints between the first-layer divided patterns is not considered as described above. High-precision joint alignment can be realized by producing with a line facility using the present invention as the first-layer exposure apparatus. That is, by using the above-described mask position adjusting device means using the workpiece side alignment mark in the first-layer exposure apparatus, it is possible to align the work stage feed direction and the mask pattern direction, and to align the joints. Is possible. At that time, a workpiece sage feed error is detected and corrected to enable more accurate joint alignment.
[0081]
Hereinafter, as a fourth embodiment, alignment adjustment in the case where the second layer exposure is performed by the divided sequential proximity exposure apparatus of the present invention to which a function dedicated to the second and subsequent layers is added will be described.
When performing continuous exposure for the second and subsequent layers using a conventional exposure apparatus, the work stage 2 is moved in the Y direction toward the exposure position for the second step after completion of the work alignment for the first step exposure. In this case, the work stage 2 is fed as it is, depending on the feed accuracy of the work stage 2, or the substrate W is mounted with the feed error of the work stage 2 (the tilt in the Y-axis traveling direction) as much as possible, and then the second stage. The method of performing the alignment of the step is taken.
[0082]
However, in such a method, when detecting the workpiece-side alignment mark 75 in the second step, the tilt accuracy (the size of the tilt angle θw) of the substrate W when the substrate W is loaded on and mounted on the work stage 2. Depending on the size of the workpiece stage feed amount y, the workpiece side alignment mark 75 at the position of the second step may not be within the field of view of the alignment camera 16, and the workpiece side alignment mark 75 is captured within the field of view. However, it takes time to complete the work alignment, and in the worst case, the work alignment in the second step becomes impossible.
[0083]
This embodiment can solve such a problem in the exposure after the second layer, and will be specifically described with reference to FIGS. As the apparatus, the divided sequential proximity exposure apparatus of the present invention described above is applied. Although the description up to the second step has been described, the present invention can be similarly applied to the subsequent steps.
[0084]
First step [FIG. 20A]:
This is a stage of preparation before the second layer exposure.
A mask M for second layer exposure is mounted on the mask stage 1. The mask marks 76 and 76 of the mounted second-layer exposure mask M are aligned with the centers of the visual fields A and A of the alignment cameras 16, respectively. Before sending the work stage 2 to the position of the second step, the center axis of the field of view A of the alignment camera 16 with respect to the actual feed direction (Y ′ direction) of the work stage 2 (that is, the two left and right alignment cameras 16). The deviation angle θm (hereinafter referred to as mask deviation angle θm) of the orthogonality of XA) is obtained in advance.
[0085]
This mask displacement angle θm is a displacement angle between the Y axis of the mask M and its actual relative feed direction Y ′, and the inclination of the running direction of the Y axis and the workpiece side alignment mark 75 during the first exposure. This is the same as the angle θ (see FIG. 7), and is the same as replacing the workpiece side alignment mark 75 with the camera field of view A in that case. An example of how to determine the mask displacement angle θm will be described later.
[0086]
Second step [FIG. 20B]:
The substrate W that has undergone the first-layer exposure is loaded on and mounted on the work stage 2. The substrate W is usually mounted in a state of being inclined relative to the actual feed direction Y ′ of the work stage 2 in the clockwise (plus) or counterclockwise (minus) direction. FIG. 20B shows a state immediately after the substrate W is mounted. The inclination angle θW of the substrate W with respect to the feed direction Y ′ is orthogonal to the axis line XW (hereinafter referred to as the work alignment axis line) XW connecting the centers of the cross-shaped workpiece side alignment marks 77 and the actual feed direction Y ′ of the work stage 2. It is an angle formed with the axis XY (hereinafter referred to as a workpiece tilt angle θW).
[0087]
In this case, the workpiece side alignment mark 77 and the mask side alignment mark 7676 still have a deviation, and the deviation angle (mask inclination angle) α corresponds to the angle formed by the workpiece alignment axis XW and the central axis XA of the camera field A. ing. In other words, the workpiece inclination angle θW in this case is θW = θm + (minus α), which is smaller than the deviation angle θm of the mask M by a deviation angle α between the mask M and the substrate W in the counterclockwise direction.
[0088]
Third step [FIG. 20 (c)]:
This is the first step of the second layer exposure. Alignment between the mounted substrate W and the mask M is performed to eliminate the deviation between them. That is, the mask M is moved with respect to the substrate W to eliminate the deviation. Specifically, the mask M is rotated counterclockwise around the Z axis by operating the mask position adjusting means 14 to align the square mask side alignment mark 76 with the cross-shaped workpiece side alignment mark 77. The turning angle of the mask M at that time, that is, the mask inclination angle α is stored in the storage device of the exposure position correction control means. FIG. 20C shows a state when the alignment between the workpiece side alignment mark 77 and the mask side alignment mark 76 in the first step in the second layer exposure is completed. Thereafter, the first exposure is performed.
[0089]
Fourth step [FIG. 20D]:
After the exposure of the first step is completed, the work stage 2 is sent to the exposure position of the second step by the work stage feeding mechanism 7. In the feed operation, a feed amount (distance) y is measured by a laser interferometer 744 that detects feed in the Y-axis direction. Next, the mask M is rotated counterclockwise by the workpiece inclination angle θW to start the second step alignment. Before that, the mask position adjustment means 14 of the mask stage 1 corrects the position of the mask M. Do. Specifically, using the feed amount (distance) y of the work stage 2, the mask displacement angle θm obtained in the first step, and the mask inclination angle α obtained in the third step, the X of the mask stage 1 is expressed by the following equation. An axial correction amount ΔX is calculated.
[0090]
ΔX = y · sin (θm + α)
Then, the mask stage 1 is moved in the X direction by the distance of ΔX to correct the position. By this mask position correction, the cross-shaped workpiece-side alignment mark 77 and the rectangular mask-side alignment mark 76 for the second step are always in the visual field of the alignment camera 16. Therefore, in the detection of the workpiece side alignment mark after the second step, no alignment error occurs regardless of the inclination angle θW when the substrate W is mounted and the feed amount in the Y direction. In addition, the takt time of the apparatus is greatly reduced.
[0091]
Theoretically, in the second and subsequent steps, the mask stage moves to the alignment completion position when entering the field of view by accurately performing the above calculation and its correction. Alignment is not necessary (that is, alignment is automatically performed by operating the mask position adjusting means 14 in response to a command from the correction control means, and exposure of 2 steps or n steps can be performed in one alignment).
Thus, global alignment exposure that does not require work alignment after the second step is possible, and it is possible to further reduce the apparatus tact time and improve accuracy.
[0092]
In the fourth embodiment, when detecting the workpiece side alignment mark 77 in the second step and subsequent steps in the second layer exposure, the actual feed direction Y ′ of the work stage 2 previously obtained at the time of the first layer exposure is obtained. By recognizing the substrate W posture from the result of the work alignment of the first step during the second layer exposure and correcting the position of the mask stage, the work side alignment mark is displayed after the second step of the second layer exposure. Although the case where control is performed so as to be always captured within the field of view of the alignment camera has been described, such a control method is not necessarily applied only after the second layer exposure. By knowing the actual feed direction Y ′ of the work stage 2 experimentally in advance, it can also be applied to the case of the tilt angle θ of the workpiece side alignment mark in the first-layer exposure and the tilt θ of the work stage running direction. is there.
[0093]
Here, an example of how to determine the mask displacement angle θm will be described.
FIG. 21A shows the state of the first step in the second layer exposure. That is, as in FIG. 20A, the mask side alignment marks (□ marks) 77A and 77B of the mask M are aligned with the centers of the visual fields CA and CB (◯ marks) of the respective alignment cameras. At this time, the deviation angle θm of the visual field center axis XA of the camera with respect to the axis XY perpendicular to the actual running direction Y ′ of the work stage is measured in advance by the following method.
[0094]
(1) The work stage is fed and the mask M is relatively moved to the position of the second step. Since the actual feed direction is the Y ′ direction, the workpiece side alignment marks 77AI and 77BI at the position I of the first step move to the position II along the Y ′ direction to move the workpiece side alignment marks 77AII and 77BII. [FIG. 21 (b)].
[0095]
(2) The measurement reference is a line Ls connecting 77BI-77BII, and the substrate W is horizontally turned so that the reference line Ls is in the X direction. Then, the inclination angles θm1 and θm2 of the straight lines 77BI-77AI and 77BII-77AII with respect to the reference line Ls are obtained [FIG. 21 (c)].
θm = (θm1 + θm2) / 2
= (Tan-1g1 / G1 + tan-1g2 / G2) / 2
It is.
[0096]
For higher accuracy, the average may be taken up to n steps.
θm = (θm1 + θm2 + ... + θmn) / n
In each of the above embodiments, the mask stage 1 is fixedly attached to the apparatus base 4 with the mask stage support 12 and the work stage 2 is moved up and down by the gap adjusting means 6. However, the present invention is not limited to this. For example, the mask stage support 12 may be configured by a cylinder so that the mask stage 1 is moved up and down. In that case, the Z-axis coarse movement stage 62 having the vertical coarse movement device can be omitted.
[0097]
Further, in each of the above-described embodiments, the work stage is configured to be movable in the Y-axis direction. Instead, the mask stage and the exposure unit may be configured to be movable in the Y-axis direction.
[0098]
【The invention's effect】
As is apparent from the above description, according to the present invention, it is possible to perform step exposure on a substrate of a predetermined size with high accuracy and high throughput in multi-planar exposure of a flat panel display.
[Brief description of the drawings]
FIG. 1 is a partially exploded perspective view for explaining a divided sequential proximity exposure apparatus according to a first embodiment of the present invention.
FIG. 2 is an enlarged perspective view of a mask stage portion.
3A is a cross-sectional view taken along the line III-III in FIG. 2, and FIG. 3B is a plan view taken along the arrow b in FIG.
FIG. 4 is a side view showing a basic structure of an alignment camera and a focus adjustment mechanism of the alignment camera.
FIG. 5 is an explanatory diagram for explaining an irradiation optical system of a workpiece side alignment mark.
FIG. 6 is a configuration diagram illustrating a focus adjustment mechanism of an alignment image.
FIG. 7 is an explanatory diagram for explaining step exposure.
FIG. 8 is a plan view of a substrate W (1000 mm × 1200 mm) having nine chamfered 18-inch display materials DP.
FIGS. 9A and 9B are diagrams showing a mask disposed opposite to the substrate of FIG. 8, wherein FIG. 9A is a plan view of a mask used in the case of 3-step exposure, and FIG. 9B is a plan view of the mask used in the case of 2-step exposure; FIG.
FIG. 10 is a view showing a mask disposed to face a substrate W (1000 mm × 1200 mm) obtained by twelve chamfering (long side direction 4 × short side direction 3) of a 15-inch display material DP, and is used in the case of two-step exposure. It is a top view of a mask.
FIG. 11 is a graph showing the relationship between the vertical (long side) dimension of the mask and the maximum deflection amount due to its own weight when the horizontal (short side) dimension of the mask is constant.
12 is a graph showing the relationship among light source illuminance, resist sensitivity, number of steps, and tact time when the masks of FIGS. 9A and 9B are used. FIG.
13 is a graph showing the relationship among light source illuminance, resist sensitivity, number of steps, and tact time when the mask of FIG. 10 and a 4-step exposure mask (not shown) are used.
FIGS. 14A and 14B are diagrams for explaining an irradiation region switching operation by the irradiation region switching unit, in which FIG. 14A shows a state in which the irradiation region is widened, and FIG. 14B shows a state in which the irradiation region is narrowed; It is.
FIGS. 15A and 15B are diagrams showing two types of optical integrators. FIG. 15A is a side view of a type with a large curvature radius of a lens surface, and FIG. 15B is a side view of a type with a small curvature radius of a lens surface.
FIG. 16 is a perspective view for explaining an example of a switching mechanism of the irradiation region switching means.
FIG. 17 is a perspective view for explaining a modified example of the switching mechanism.
FIG. 18 is an explanatory diagram for explaining a divided sequential proximity exposure apparatus according to a second embodiment of the present invention.
FIG. 19 is an explanatory diagram for explaining a divided sequential proximity exposure apparatus according to a third embodiment of the present invention.
20A and 20B are diagrams for explaining a divided sequential proximity exposure apparatus according to a fourth embodiment of the present invention, in which FIG. 20A is a schematic diagram showing preparation before exposure and alignment after mask loading; (C) is a schematic diagram which shows the alignment completion state of the 1st step, (d) is a schematic diagram which shows the state after moving to the alignment of the 2nd step.
FIGS. 21A and 21B are diagrams for explaining how to obtain a mask displacement angle θm, in which FIG. 21A is a plan view showing a state of the first step in the second layer exposure, and FIG. 21B is a position of the mask M at the second step; FIG. 7C is a plan view showing a state when measuring mask displacement angles θm1 and θm2. FIG.
[Explanation of symbols]
W ... Board
M ... Mask
P ... Mask pattern
1 ... Mask stage
2. Work stage
3. Illumination optical system (irradiation means)
6. Gap adjustment means
7 ... Work stage feed mechanism
33a, 33b ... Optical integrator
200A ... Irradiation area switching means
200 ... switching mechanism

Claims (3)

A work stage that holds a substrate as a material to be exposed, a mask stage that is disposed opposite to the substrate and holds a mask smaller than the substrate, and irradiates the substrate with light for pattern exposure via the mask. An irradiation means; a work stage feed mechanism for moving the work stage and the mask stage relative to each other so as to oppose the mask pattern of the mask to a plurality of predetermined positions on the substrate; and the mask and the substrate And a gap adjusting means for adjusting a gap between the opposing surfaces of the workpiece stage, wherein the work stage feed mechanism has two or more steps, and the mask pattern is exposed and transferred onto the substrate at each step. In the exposure apparatus,
The size of the mask and the number of steps are determined based on the relationship between the resist sensitivities and the exposure illuminance at which the allowable deflection amount of the mask, the size of the pattern area of the mask and the tact time are shortest and the required exposure accuracy is obtained. Further, the irradiation means comprises an irradiation area switching means capable of switching the irradiation area in the step direction of the exposure light according to the exposure conditions at the set number of steps. Proximity exposure device.   The irradiation area switching unit includes a plurality of types of optical integrators having different emission angles, and a switching mechanism that selectively positions and arranges the center of each optical integrator with respect to the optical axis of the irradiation unit. The divided sequential proximity exposure apparatus according to claim 1. A mask smaller than the substrate as an exposed material is disposed close to and opposed to the substrate, the substrate is stepped relative to the mask, and the mask pattern of the mask is placed at a plurality of predetermined positions on the substrate. Division in which the mask pattern of the mask is exposed and transferred onto the substrate by irradiating the substrate with pattern exposure light through the mask at each step with two or more steps. In the sequential proximity exposure method,
The size of the mask and the number of steps are determined based on the relationship between the resist sensitivities and the exposure illuminance at which the allowable deflection amount of the mask, the size of the pattern area of the mask and the tact time are shortest and the required exposure accuracy is obtained. And setting an irradiation region in the step direction of the exposure light according to the exposure condition at the set number of steps.

Images