JP2004311904A - Stage controlling device and aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stage controlling device which can improve synchronizing accuracy and throughput of a stage and an aligner with the device. <P>SOLUTION: In an aligner having a reticle rough-movement stage unit RCS and a reticle fine movement stage unit RFS as a reticle stage, the reticle fine movement stage unit RFS is controlled by feed back control and feed forward control. Acceleration information obtained from a feedback signal FS1 output from a laser interferometer 32 in previous operation is stored in the acceleration table 64. The reticle fine movement stage unit RFS is subjected to feed forward control by using a control signal DS3 obtained by acceleration velocity information stored in the acceleration table 64 via a zero phase filter 65. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００５１】
上記（１）式の方程式で示したフィルタにおいては、順方向（過去から未来への時間方向）でフィルタ処理を行った後、フィルタ処理を行ったデータ列を逆にして、再度フィルタリングを行う。このようにして得られるデータ列は、厳密に位相歪みがゼロなる。ここで、ゼロ位相フィルタは、現在のサンプリング点における値を求めるために、未来のサンプリング点における値を用いているため、非因果的なフィルタであるということができる。
【００５２】
本実施形態においは、このような非因果的なゼロ位相フィルタ６５を用いているため、ウェハステージユニットＷＳ並びにレチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳを移動させている最中にレーザ干渉計３２から出力される帰還信号ＦＳ１を用いてレチクル微動ステージユニットＲＦＳのフィードフォワード制御を行うことはできない。このため、ウェハステージユニットＷＳ並びにレチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＷＦＳの移動動作に再現性があることを前提として、以前にこれらのステージを同期させて動作させたときの、レーザ干渉計３２から出力される帰還信号ＦＳ１に対して時間微分を２回行って得た加速度情報を用い、この加速度情報をゼロ位相フィルタ６５を介して位相歪みのない制御信号ＤＳ３を得て、レチクル微動ステージユニットＲＦＳのフィードフォワード制御を行っている。
【００５３】
尚、上述したゼロ位相フィルタとしては、ＦＩＲフィルタ（有限インパルス応答フィルタ）とＩＩＲフィルタ（無限インパルス応答フィルタ）とを設計することができる。ここで、ＦＩＲフィルタは、直線位相特性を正確に実現でき、フィルタの安定性が常に保証されるという言う利点を有するが、急峻な振幅周波数特性（カットオフ特性）を実現するときはフィルタの次数大きく取る必要がある。一方、ＩＩＲフィルタは、低次数で希望の振幅周波数特性を実現できるという利点を有するが、群遅延特性の歪みが大きくなり、安定性は常に保証されない。本実施形態では、同期精度の向上のためにＦＩＲフィルタを用いることが好ましい。
【００５４】
ここで、加速度テーブル６４及びゼロ位相フィルタ６５を用いてレチクル微動ステージユニットＲＦＳをフィードフォワード制御するのは、レチクル微動ステージユニットＲＦＳの位置決めに要する時間及び設定速度に達する時間を仕様で定められた時間内に収めるため、及び同期精度を仕様で定められた同期精度内に収めるためである。加算器６３は、ＰＩＤタイプコントローラ６２から出力される制御信号ＣＳ３とゼロ位相フィルタ６５から出力される制御信号ＤＳ３とを加算して、実際にレチクル微動ステージユニットＲＦＳに与える制御信号ＣＳ３０を出力する。
【００５５】
以上のように、レチクル微動ステージ制御部３３ｃは、レチクル粗動ステージ制御部３３ｂと同様に、レーザ干渉計３７から出力される帰還信号ＦＳ３を用いたフィードバック制御系と、以前にウェハステージユニットＷＳ並びにレチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳを同期させて動作させたときの、レーザ干渉計３２から出力される帰還信号ＦＳ１に対して時間微分を２回行って得た加速度情報を用いたフィードフォワード制御系とを備える。
【００５６】
尚、上記の加速度情報は、以前（過去）にウェハステージユニットＷＳ並びにレチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳを同期させて移動させたときに得た情報であれば良いわけであるが、露光装置の運転（動作）中に自動学習によって更新され、加速度テーブル６４に記憶させるようにするのが好ましい。ここで用いる学習方法は、例えば遺伝子アルゴリズム（Ｇｅｎｅｔｉｃ Ａｌｇｏｒｉｔｈｍ）を用いた学習方法又はニューラルネットワークを用いた学習方法等の学習方法を用いることができる。ここで、遺伝子アルゴリズムとは、集団及び環境との相互作用を通じて環境に適応する個体が生き残り、交配による世代間での優れた形質の継承及び突然変異による新しい形質の獲得を通じて進化してきた生物進化のメカニズムをシミュレートする人工的モデルをいい、自然システムや人工システムの環境への適応過程をシミュレートするモデルである。
【００５７】
以上、本発明の一実施形態によるステージ制御装置としての制御装置３３の構成について説明したが、次にゼロ位相フィルタ６５を備えるフィードフォワード制御系のシミュレーション結果について説明する。図４は、ゼロ位相フィルタ６５の入出力特性をシミュレートした結果を示す図である。尚、本実施形態では、２０次のゼロ位相フィルタ６５を設計し、このゼロ位相フィルタ６５のシミュレート結果を説明する。
【００５８】
図４に示したシミュレート結果においては、横軸に時間をとり、縦軸に加速度をとっている。符号Ｌ１を付した曲線はゼロ位相フィルタ６５の入力信号を示し、符号Ｌ２を付した曲線はゼロ位相フィルタ６５の出力信号を示す。入力信号Ｌ１は、レーザ干渉計３２から出力される帰還信号ＦＳ１に対して所定の処理（例えば、値を４倍する処理）を行い、この信号に時間微分を２回施して得られる信号であり、加速度テーブル６４に記憶される加速度情報を示す信号に相当する。尚、図４においては、入力信号Ｌ１と出力信号Ｌ２とを明りょうに区別するため、出力信号Ｌ２の値を１．０５倍している。
【００５９】
まず、縦軸方向に注目すると、入力信号Ｌ１にはウェハステージユニットＷＳの振動分やノイズ等による不要な成分が重畳されていることが分かる。しかしながら、ゼロ位相フィルタ６５を介した出力信号Ｌ２は、これらの不要な成分が除去されて滑らかな曲線になっていることが分かる。次に、横軸方向に着目すると、入力信号Ｌ１において加速度が極大とみなせる値になる時間と、出力信号Ｌ２において加速度が極大になる時間とが一致しているため、入力信号Ｌ１と出力信号Ｌ２との位相差が生じていないことが分かる。
【００６０】
次に、ゼロ位相フィルタ６５を設けた場合とゼロ位相フィルタ６５に代えてローパスフィルタを設けた場合とのシミュレート結果について説明する。図５は、ゼロ位相フィルタ６５を設けた場合とゼロ位相フィルタ６５に代えてローパスフィルタを設けた場合とのシミュレート結果を示す図である。尚、図５においても、図４と同様に、横軸に時間をとり、縦軸に加速度をとっている。
【００６１】
図５において、符号Ｌ１１を付した曲線はゼロ位相フィルタ６５の出力信号を示し、符号Ｌ１２を付した曲線はローパスフィルタの出力信号を示す。尚、図５においては、比較のため、ウェハステージユニットＷＳの目標位置を示す基準信号ＲＳ１に対して時間微分を２回施して得た加速度曲線を示し、符号Ｌ１０を付している。また、図５中において、符号Ｍを付して示した加速度曲線の極大値付近の拡大図を図６に示す。図６は、加速度曲線の極大値付近の拡大図である。
【００６２】
まず、縦軸方向に注目すると、ゼロ位相フィルタ６５の出力信号Ｌ１１及びローパスフィルタの出力信号Ｌ１２ともに滑らかな曲線となっており、ゼロ位相フィルタ６５を用いた場合であっても、ゼロ位相フィルタ６５に代えてローパスフィルタを用いた場合であっても、ウェハステージユニットＷＳの振動分やノイズ等による不要な成分が除去されていることが分かる。
【００６３】
次に横軸方向に着目すると、図６の拡大図を示すまでもなく、図５から明らかなように、ローパスフィルタの出力信号は、ウェハステージユニットＷＳに対する加速度曲線Ｌ１０に対して位相遅れが生じていることが分かる。これに対して、図５及び図６の拡大図からも分かる通り、ゼロ位相フィルタ６５の出力信号Ｌ１１は、ウェハステージユニットＷＳに対する加速度曲線Ｌ１０と同位相であり、位相歪みが生じていないことが分かる。
【００６４】
以上、ゼロ位相フィルタ６５を設けてレチクル微動ステージユニットＲＦＳをフィードフォワード制御する場合と、ゼロ位相フィルタ６５に代えてローパスフィルタを設けてレチクル微動ステージユニットＲＦＳをフィードフォワード制御する場合とのシミュレーション結果について説明した。次に、過去の加速度情報を用い、ゼロ位相フィルタ６５を介してフィードフォワード制御する場合と、ウェハステージユニットＷＳの基準信号ＲＳ１に対して時間微分を２回施して得た信号を用いてレチクル微動ステージユニットＲＦＳをフィードフォワード制御する場合のシミュレーション結果について説明する。
【００６５】
図７は、過去の加速度情報を用いてゼロ位相フィルタ６５を介した信号によりレチクル微動ステージのフィードフォワード制御を行う場合と、ウェハステージユニットＷＳの基準信号ＲＳ１を用いてレチクル微動ステージのフィードフォワード制御を行う場合とのシミュレーション結果を示す図である。尚、図７（ａ）は同期誤差の標準偏差を示す図であり、図７（ｂ）は、図７（ａ）に示す曲線をフーリエ変換したときのフーリエ成分の分布を示す図である。
【００６６】
図７（ａ）において、符号Ｌ２１を付した曲線は、過去の加速度情報を用いてゼロ位相フィルタ６５を介した信号によりレチクル微動ステージのフィードフォワード制御を行った場合における同期誤差の標準偏差を示す曲線であり、符号Ｌ２２は、ウェハステージユニットＷＳの基準信号ＲＳ１を用いてレチクル微動ステージのフィードフォワード制御を行った場合における同期誤差の標準偏差を示す曲線である。
【００６７】
この図７（ａ）から符号Ｌ２２を付した曲線よりも、符号Ｌ２１を付した曲線の方が、同期誤差の標準偏差が小さいことが分かる。この同期誤差の標準偏差は、その値が小さいほど、ウェハステージユニットＷＳと、レチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳとの同期精度が高いことを意味している。よって、レチクル微動ステージユニットＲＦＳのフィードフォーワード制御を行うには、ウェハステージユニットＷＳの基準信号ＲＳ１を用いるよりも、本実施形態のように過去の加速度情報を用いてゼロ位相フィルタ６５を介した信号を用いてフィードフォワード制御した方が高い同期精度を得ることができる。
【００６８】
また、図７（ｂ）において、符号Ｌ３１を付した曲線は、図７（ａ）中の符号Ｌ２１を付して示す曲線をフーリエ変換したときのフーリエ成分の分布を示す図であり、符号Ｌ３２を付した曲線は、図７（ａ）中の符号Ｌ２２を付して示す曲線をフーリエ変換したときのフーリエ成分の分布を示す図である。図７（ｂ）から、符号Ｌ３１付した曲線は、図７（ｂ）に示す周波数領域のほぼ全域に亘って、フーリエ成分の振幅が小さく抑えられていることが分かる。これに対し、符号Ｌ３２を付した曲線は、低周波領域（図７（ｂ）中の周波数ｆ_１〜ｆ_２付近の周波数領域）においてフーリエ成分が特に大きく、しかも周波数が高くなるにつれてフーリエ成分の振幅が高くなる箇所と低くなる箇所が周期的に現れている。
【００６９】
フーリエ成分の振幅が高いと、一方のステージ（例えば、ウェハステージユニットＷＳ）に対して他方のステージ（例えば、レチクル粗動ステージユニットＲＣＳ、レチクル微動ステージユニットＲＦＳ）がある周波数で振動していることを意味しているため、同期精度を高めるためにはフーリエ成分の振幅は小さい方が良い。このように、フーリエ変換の結果からも、本実施形態のように過去の加速度情報を用いてゼロ位相フィルタ６５を介した信号を用いてフィードフォワード制御した方が高い同期精度を得ることができることが分かる。
【００７０】
以上、過去の加速度情報を用いてゼロ位相フィルタ６５を介した信号によりレチクル微動ステージユニットＲＦＳをフィードフォワード制御する場合の制御特性について説明したが、次に露光時の動作について簡単に説明する。露光動作が開始されると、制御装置３３はウェハステージユニットＷＳ及びレチクルステージユニット（レチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳ）の加速度を上昇させる。
【００７１】
具体的には、図３に示す目標位置発生器５０から目標位置を与える基準信号ＲＳ１が発生され、この基準信号ＲＳ１とレーザ干渉計３２から出力される帰還信号ＦＳ１とに基づいてＰＩＤタイプコントローラ５２が制御信号ＣＳ１を出力するとともに、コントローラ５４が基準信号ＲＳ１に基づいてフィードフォワード制御のための制御信号ＤＳ１を出力する。これら制御信号ＣＳ１と制御信号ＤＳ１は加算器５３で加算されて制御信号ＣＳ１０としてウェハステージユニットＷＳに供給されてウェハステージユニットＷＳの加速が行われる。
【００７２】
また、基準信号ＲＳ１は変換回路５５で基準信号ＲＳ２に変換され、ＰＩＤタイプコントローラ５７は、この基準信号ＲＳ２とレーザ干渉計３５から出力される帰還信号ＦＳ２とに基づいて制御信号ＣＳ２を出力するとともに、コントローラ５９が基準信号ＲＳ２に基づいてフィードフォワード制御のための制御信号ＤＳ２を出力する。これら制御信号ＣＳ２と制御信号ＤＳ２は加算器５８で加算されて制御信号ＣＳ２０としてウェハステージユニットＷＳに供給されてウェハステージユニットＷＳの加速が行われる。
【００７３】
更に、レーザ干渉計３２の帰還信号ＦＳ１は変換マトリックス回路６０で基準信号ＲＳ３に変換され、ＰＩＤタイプコントローラ５２が、この基準信号ＲＳ３とレーザ干渉計３７から出力される帰還信号ＦＳ３とに基づいて制御信号ＣＳ３を出力する。また、加速度テーブル６４からは以前に動作を行って記憶されている加速度情報がゼロ位相フィルタ６５へ出力され、ゼロ位相フィルタ６５からフィードフォワード制御のための制御信号ＤＳ３が出力される。ここで、加速度テーブル６４から出力される加速度情報は、ウェハＷ内におけるパターンを転写すべきショット領域の位置、及び、ウェハステージユニットＷＳ及びレチクル粗動ステージユニットＲＣＳの移動方向に応じた加速度情報である。
【００７４】
加速期間が終了して、ウェハステージユニットＷＳ、並びに、レチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳ各々の速度が一定の速度になると、スリット状の照明光をレチクルＲに照射しつつ、ウェハステージユニットＷＳを−Ｙ方向に速度Ｖｗ（＝β・Ｖｍ）で走査移動するとともに、レチクルステージユニットを＋Ｙ方向に速度Ｖｍで走査移動しつつ、レチクルに形成されたパターンを、投影光学系１４を介してウェハＷ上に設定されたショット領域に転写する。１つのショット領域に対してレチクルのパターンの転写が終了すると、ウェハステージユニットＷＳ及びレチクルステージユニットを減速させて、レチクルＲへの照明光の照射を停止させる。
【００７５】
次に、制御装置３３は、ウェハステージユニットＷＳを駆動して、次にパターンを転写するショット領域を投影光学系ＰＬの投影領域（レチクルＲのパターンが投影される領域）の近傍に移動させる。そして、上述した動作と同様に、ウェハステージユニットＷＳ、並びに、レチクル粗動ステージユニットＲＣＳ及びレチクル微動ステージユニットＲＦＳを加速して一定速度になった後、照明光をレチクルＲに照射して、レチクルのパターンをショット領域に逐次転写する。図８は、パターン転写時における投影領域に対するウェハＷの移動経路の一例を示す図である。この図に示すように、ショット領域ＳＡを転写する際には、ウェハＷはＹ方向（＋Ｙ方向又はーＹ方向）に沿って一定速度で移動する。一方、１つのショット領域に対する露光処理が終了し、次に露光処理すべきショット領域に移るときには、加速及び減速しつつＸ方向（または、Ｙ方向）にステップ移動する。このような動作を繰り返して、ウェハＷ上に設定された全てのショット領域に対する露光処理を行う。
【００７６】
以上、本発明の実施形態について説明したが、本発明は上記実施形態に制限されず、本発明の範囲内で自由に変更が可能である。例えば、上記実施形態ではステップ・アンド・スキャン方式の露光装置を例に挙げて説明したが、ステップ・アンド・リピート方式の露光装置にも適用可能である。また、光源としては、ＫｒＦエキシマレーザ（２４８ｎｍ）、ＡｒＦエキシマレーザ（１９３ｎｍ）等のエキシマレーザに限らず、超高圧水銀ランプから射出されるｇ線（４３６ｎｍ）及びｉ線（３６５ｎｍ）、Ｆ_２レーザ（１５７ｎｍ）から射出されるレーザ光、Ｋｒ_２レーザ（１４６ｎｍ）から射出されるレーザ光、Ａｒ_２レーザ（１２６ｎｍ）から射出されるレーザ光、更には、Ｘ線や電子線などの荷電粒子線を用いることができる。
【００７７】
また、上記実施形態において、図３に示したコントローラ５２，５７，６２はＰＩＤタイプコントローラ、Ｐ（Ｐｒｏｐｏｒｔｉｏｎａｌ：比例）タイプコントローラ及びＰＩ（Ｐｒｏｐｏｒｔｉｏｎａｌ Ｉｎｔｅｇｒａｌ：比例積分）タイプコントローラの何れであっても良い。また、コントローラ５２，５７，６２は現在制御理論に基づいたロバストコントローラであっても良い。更に、図３に示した制御装置３３は、電子回路によりハードウェア的に構成されていても良く、ソフトウェア的に構成されていても良い。各ブロックをソフトウェア的に構成する場合には、各ブロックの機能を規定するプログラムをＣＰＵ（中央処理装置）が実行することにより、各ブロックの機能が実現される。
【００７８】
次に、本発明の実施形態による露光装置をリソグラフィ工程で使用したマイクロデバイスの製造方法について簡単に説明する。図９は、マイクロデバイス（ＩＣやＬＳＩ等の半導体チップ、液晶パネル、ＣＣＤ、薄膜磁気ヘッド、マイクロマシン等）の製造工程の一例を示すフローチャートである。図９に示すように、まず、ステップＳ１０（設計ステップ）において、マイクロデバイスの機能・性能設計（例えば、半導体デバイスの回路設計等）を行い、その機能を実現するためのパターン設計を行う。引き続き、ステップＳ１１（マスク製作ステップ）において、設計した回路パターンを形成したマスク（レチクル）を製作する。一方、ステップＳ１２（ウェハ製造ステップ）において、シリコン等の材料を用いてウェハを製造する。
【００７９】
次に、ステップＳ１３（ウェハ処理ステップ）において、ステップＳ１０〜ステップＳ１２で用意したマスクとウェハを使用して、後述するように、リソグラフィ技術等によってウェハ上に実際の回路等を形成する。次いで、ステップＳ１４（デバイス組立ステップ）において、ステップＳ１３で処理されたウェハを用いてデバイス組立を行う。このステップＳ１４には、ダイシング工程、ボンティング工程、及びパッケージング工程（チップ封入）等の工程が必要に応じて含まれる。最後に、ステップＳ１５（検査ステップ）において、ステップＳ１４で作製されたマイクロデバイスの動作確認テスト、耐久性テスト等の検査を行う。こうした工程を経た後にマイクロデバイスが完成し、これが出荷される。
【００８０】
図１０は、半導体デバイスの場合における、図９のステップＳ１３の詳細なフローの一例を示す図である。図１０において、ステップＳ２１（酸化ステップ）においてはウェハの表面を酸化させる。ステップＳ２２（ＣＶＤステップ）においてはウェハ表面に絶縁膜を形成する。ステップＳ２３（電極形成ステップ）においてはウェハ上に電極を蒸着によって形成する。ステップＳ２４（イオン打込みステップ）においてはウェハにイオンを打ち込む。以上のステップＳ２１〜ステップＳ２４のそれぞれは、ウェハ処理の各段階の前処理工程を構成しており、各段階において必要な処理に応じて選択されて実行される。
【００８１】
ウェハプロセスの各段階において、上述の前処理工程が終了すると、以下のようにして後処理工程が実行される。この後処理工程では、まず、ステップＳ２５（レジスト形成ステップ）において、ウェハに感光剤を塗布する。引き続き、ステップＳ２６（露光ステップ：転写工程）において、上で説明したリソグラフィシステム（露光装置）及び露光方法によってマスクの回路パターンをウェハに転写する。次に、ステップＳ２７（現像ステップ：現像工程）においては露光されたウェハを現像し、ステップＳ２８（エッチングステップ）において、レジストが残存している部分以外の部分の露出部材をエッチングにより取り去る。そして、ステップＳ２９（レジスト除去ステップ）において、エッチングが済んで不要となったレジストを取り除く。これらの前処理工程と後処理工程とを繰り返し行うことによって、ウェハ上に多重に回路パターンが形成される。
【００８２】
以上説明したマイクロデバイス製造方法を用いれば、露光工程（ステップＳ２６）において上記の露光装置が用いられ、真空紫外域の照明光により解像力の向上が可能となり、しかも露光量制御を高精度に行うことができるので、結果的に最小線幅が０．１μｍ程度の高集積度のデバイスを歩留まり良く生産することができる。
【００８３】
また、半導体素子等のマイクロデバイスだけではなく、光露光装置、ＥＵＶ露光装置、Ｘ線露光装置、及び電子線露光装置等で使用されるレチクル又はマスクを製造するために、マザーレチクルからガラス基板やシリコンウェハ等ヘ回路パターンを転写する露光装置にも本発明を適用できる。ここで、ＤＵＶ（深紫外）やＶＵＶ（真空紫外）光等を用いる露光装置では、一般的に透過型レチクルが用いられ、レチクル基板としては石英ガラス、フッ素がドープされた石英ガラス、蛍石、フッ化マグネシウム、又は水晶等が用いられる。また、プロキシミティ方式のＸ線露光装置や電子線露光装置等では、透過型マスク（ステンシルマスク、メンブレンマスク）が用いられ、マスク基板としてはシリコンウェハ等が用いられる。なお、このような露光装置は、ＷＯ９９／３４２５５号、ＷＯ９９／５０７１２号、ＷＯ９９／６６３７０号、特開平１１−１９４４７９号、特開２０００−１２４５３号、特開２０００−２９２０２号等に開示されている。
【００８４】
【発明の効果】
この発明によれば、第２ステージに対してフィードフォワード制御するにあたり、以前に動作を行ったときに位置検出部から出力された信号に基づいて得た加速度情報を記憶部に記憶し、この加速度情報を用いて第２ステージをフィードフォワード制御しているため、第１ステージと第２ステージの同期精度を向上させることができるという効果がある。
また、第２ステージに対して、フィードフォワード制御することにより、第１ステージと第２ステージとの整定時間を短縮することができるため、スループットを向上させることができるという効果がある。
【図面の簡単な説明】
【図１】本発明の一実施形態による露光装置の構成を示す正面図である。
【図２】図１に示した露光装置に適用可能なリニアモータの断面図である。
【図３】本発明の一実施形態によるステージ制御装置の主要部をなす制御装置３３の構成を示すブロック図である。
【図４】ゼロ位相フィルタ６５の入出力特性をシミュレートした結果を示す図である。
【図５】ゼロ位相フィルタ６５を設けた場合とゼロ位相フィルタ６５に代えてローパスフィルタを設けた場合とのシミュレート結果を示す図である。
【図６】加速度曲線の極大値付近の拡大図である。
【図７】過去の加速度情報を用いてゼロ位相フィルタ６５を介した信号によりレチクル微動ステージのフィードフォワード制御を行う場合と、ウェハステージユニットＷＳの基準信号ＲＳ１を用いてレチクル微動ステージのフィードフォワード制御を行う場合とのシミュレーション結果を示す図である。
【図８】パターン転写時における投影領域に対するウェハＷの移動経路の一例を示す図である。
【図９】マイクロデバイスの製造工程の一例を示すフローチャートである。
【図１０】半導体デバイスの場合における、図９のステップＳ１３の詳細なフローの一例を示す図である。
【図１１】走査露光装置に設けられる従来のステージ制御装置の構成例を示すブロック図である。
【符号の説明】
３２ レーザ干渉計（位置検出部）
３３ ステージ制御装置（制御装置）
５２ ＰＩＤタイプコントローラ（第１制御部、制御部）
５４ コントローラ（第１制御部、制御部）
５７ ＰＩＤタイプコントローラ（第２制御部、粗動制御部）
５９ コントローラ（第２制御部、粗動制御部）
６２ ＰＩＤタイプコントローラ（第２制御部、微動制御部）
６４ 加速度テーブル（記憶部）
６５ ゼロ位相フィルタ（補助制御部）
ＦＳ１ 帰還信号（検出信号）
ＦＳ２ 帰還信号（検出信号）
ＦＳ３ 帰還信号（検出信号）
Ｒ レチクル（マスクステージ）
ＲＣＳ レチクル粗動ステージユニット（第２ステージ、マスクステージ、マスク粗動ステージ）
ＲＦＳ レチクル微動ステージユニット（第２ステージ、マスクステージ、マスク微動ステージ）
Ｗ 感光基板
ＷＳ ウェハステージユニット（第１ステージ、基板ステージ）[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a stage control apparatus and an exposure apparatus, and more particularly, to a stage control apparatus that controls the operation of a stage configured to be movable while a moving object such as a mask (reticle) or a wafer is mounted thereon, and an apparatus including the same. The present invention relates to an exposure apparatus provided.
[0002]
[Prior art]
2. Description of the Related Art In a photolithography process in a manufacturing process of a micro device such as a liquid crystal display, a semiconductor device, an imaging device (such as a CCD), and a thin film magnetic head, a circuit pattern formed on a mask or a reticle is printed on a surface through a projection optical system. An exposure apparatus that projects onto a photosensitive substrate such as a wafer or a glass plate coated with a resist is used. As one of such exposure apparatuses, there is known an exposure apparatus (stepper) of a step-and-repeat type in which a pattern formed on a reticle is collectively reduced and projected onto each shot area on a wafer. In the stepper, collective exposure is performed on one shot area, and when the exposure is completed, the operation of stepwise moving the wafer and performing collective exposure on the next shot area is repeatedly performed.
[0003]
Also, in order to enlarge the exposure range of the pattern formed on the reticle, the exposure light from the illumination optical system is limited to a slit shape, and a part of the pattern formed on the reticle is placed on the wafer using the slit light. A scanning exposure apparatus of a step-and-scan method in which a reticle and a wafer are synchronously scanned with respect to a projection optical system and a pattern is sequentially transferred onto a wafer in a reduced projection state is also used.
[0004]
Generally, in an exposure apparatus, a stage device is used for positioning a reticle and a wafer with high accuracy, or scanning a reticle and / or a wafer with high accuracy at a constant speed. In this type of stage device, for example, a linear motor is used as a driving mechanism for driving the stage at high speed and in a non-contact manner. The linear motor includes a stator and a movable element. When one of the stator and the movable element includes a coil, the other includes a magnetic body such as a magnet.
[0005]
As one form of the scanning type exposure apparatus, a reticle stage is provided with a wafer stage for holding a wafer, and a reticle stage for holding a reticle, and a reticle fine movement stage and a reticle coarse movement stage for improving synchronization accuracy. There is something. In each stage, for example, positioning and scanning operations for exposure are performed by a PID (Proportional Integral Derivative) type stage controller. In particular, since the reticle coarse movement stage moves at high speed, a linear motor and a drive amplifier for obtaining a large thrust are required.
[0006]
FIG. 11 is a block diagram showing a configuration example of a conventional stage control device provided in a scanning exposure apparatus. Here, it is assumed that each of the wafer stage and the reticle stage includes an amplifier model and a driving mechanism such as a linear motor. Further, a negative feedback circuit using a PID type controller is formed for each stage. In FIG. 11, a negative feedback circuit is generated from the arithmetic unit 101, the wafer controller 102, the wafer stage 103, and the laser interferometer 104 for the wafer stage 103, and the arithmetic unit 106, the reticle controller 107 for the reticle stage 108. , Reticle stage 108 and laser interferometer 109 form a negative feedback circuit. Note that the above-described scanning type exposure apparatus includes a reticle fine movement stage for holding the reticle and a reticle coarse movement stage, but these are collectively referred to as a reticle stage 108 in FIG.
[0007]
The target position generator 100 outputs a target position signal indicating the target position of the wafer stage 103. The arithmetic unit 101 obtains a deviation between the target position signal output from the target position generator 100 and the feedback signal output from the laser interferometer 104 and outputs it as a deviation signal. Wafer controller 102 outputs a control signal indicating a thrust applied to wafer stage 103 based on the deviation signal output from operation unit 101. This control signal is amplified by an amplifier (not shown) and supplied to each drive mechanism of the wafer stage 103. Laser interferometer 104 measures the position of wafer stage 103, and outputs the measurement result as a feedback signal.
[0008]
The feedback signal output from the laser interferometer 104 is input to the conversion circuit 105 and is converted into a target position signal indicating the target position of the reticle stage 108. In the example shown in FIG. 11, since the projection magnification of the projection optical system (not shown) is set to 、, the conversion circuit 105 is set to a circuit that quadruples the feedback signal from the laser interferometer 104. That is, when the projection magnification of the projection optical system is 1/4, in order to move the wafer stage 103 and the reticle stage 108 in synchronization with each other, the amount of movement of the reticle stage 108 must be four times the amount of movement of the wafer stage 43. Therefore, the conversion circuit 105 is set to a circuit that quadruples the feedback signal from the laser interferometer 104.
[0009]
The target position signal from the conversion circuit 105 is input to the calculation unit 106. The operation unit 106 calculates the deviation between the target position signal from the conversion circuit 105 and the feedback signal from the laser interferometer 109 and outputs the deviation as a deviation signal. Reticle controller 107 outputs a control signal indicating a thrust applied to reticle stage 108 based on the deviation signal output from arithmetic unit 106. This control signal is amplified by an amplifier and supplied to each drive mechanism of reticle stage 108. Laser interferometer 109 measures the position of reticle stage 108 and outputs the measurement result as a feedback signal.
[0010]
In the stage control device having the above configuration, the wafer controller 102 controls the operation of the wafer stage 103 based on the target position signal output from the target position generator 100, and the reticle controller 107 controls the feedback of the feedback circuit for the wafer stage 103. Since the operation of reticle stage 108 is controlled based on the converted signal (target position signal), a so-called master / slave control system is configured.
[0011]
When the wafer stage 103 and the reticle stage 108 are moved synchronously, first, a target position signal is output from the target position generator 100, and a deviation between the target position signal and a feedback signal output from the laser interferometer 104 is calculated. The wafer controller 102 outputs a control signal to the wafer stage 103 based on a deviation signal obtained by the unit 101 and indicating the deviation. The feedback signal from the laser interferometer 104 is amplified four times in the conversion circuit 105 and output as a target position signal. The deviation between the target position signal and the feedback signal output from the laser interferometer 109 is calculated by the calculation unit 106 The reticle controller 107 outputs a control signal to the reticle stage 108 based on the deviation signal indicating the deviation.
[0012]
The wafer stage 103 and the reticle stage 108 follow each input control signal and are accelerated. Then, at a fixed speed, the wafer stage 103 and the reticle stage 108 project in an inverted manner of a reticle pattern on a wafer by a projection optical system (not shown). Move) in sync with. In this state, the reticle stage 108 and the wafer stage 103 are synchronized while projecting a part of the pattern formed on the reticle onto the wafer for one shot set on the wafer by irradiating the reticle with illumination light. By moving, the reticle pattern is sequentially transferred to the shot area. When the transfer of the pattern formed on the reticle to one shot area is completed, the reticle stage 108 and the wafer stage 103 are stopped after deceleration following the input control signal. The above operation is sequentially repeated for other shot areas to transfer the reticle pattern to the entire surface of the wafer. For details of the master-slave control device, refer to, for example, Patent Documents 1 and 2 below.
[0013]
[Patent Document 1]
JP-A-2000-347774
[Patent Document 2]
JP-A-10-125594
[0014]
[Problems to be solved by the invention]
By the way, in the above-described exposure apparatus, particularly in the scanning exposure apparatus, the pattern formed on the reticle is sequentially transferred onto the wafer while the reticle and the wafer are synchronously moved. In order to transfer data to the reticle, it is necessary to minimize the synchronization error between the reticle and the wafer to increase the synchronization accuracy. Further, in order to increase the manufacturing efficiency of the micro device, it is required to improve the throughput, that is, the number of wafers that can perform the exposure processing per unit time.
[0015]
However, especially in the manufacture of semiconductor devices, when a CPU (Central Processing Unit) is taken as an example, the process rule is extremely fine, about 0.13 μm. It has become difficult to obtain the synchronization accuracy required by fine process rules. Also, as the speed of the wafer stage and the reticle stage increases, the setting time tends to increase. Here, the settling time is a time required for the vibration generated when the acceleration of the wafer stage or the reticle stage ends the operation and shifts to the constant velocity motion to converge. The shorter the setting time is, the shorter the time required to synchronize the wafer stage and the reticle stage is. Therefore, it is necessary to shorten the settling time in order to improve the throughput.
[0016]
The present invention has been made in view of the above circumstances, and has as its object to provide a stage control device capable of improving the synchronization accuracy and throughput of a stage, and an exposure apparatus including the device.
[0017]
[Means for Solving the Problems]
In order to solve the above problem, a stage control device of the present invention controls a second stage (RCS, RFS) so as to move in synchronization with movement of a first stage (WS). A first controller (52, 54) for generating a control signal indicating a thrust of the first stage (WS) in accordance with a target position of the first stage (WS); and a first stage (WS). And a detection signal (FS1) output from the position detection unit (32) is used as a target position of the second stage (RCS, RFS). A second control unit (57, 59, 62) for generating a control signal indicating a thrust of the RCS, RFS), and the second stage obtained based on a signal previously output from the position detection unit (32). (RCS A storage unit (64) for storing acceleration information indicating acceleration of the RFS), and using the acceleration information stored in the storage unit (64), to the second control unit (57, 59, 62). And an auxiliary control unit (65) for feedforward control.
According to the present invention, when feedforward control is performed on the second stage, acceleration information obtained based on a signal output from the position detection unit when the operation was previously performed is stored in the storage unit. Since the second stage is feedforward controlled using the information, the synchronization accuracy of the first stage and the second stage can be improved. Also, by performing feedforward control on the second stage, the settling time between the first stage and the second stage can be shortened, so that the throughput can be improved.
Also, in the stage control device according to the present invention, the auxiliary control unit (65) includes a linear phase filter, and supplies the acceleration information via the linear phase filter to the second control unit (57, 59, 62). And the feedforward control is performed.
Here, it is preferable that the acceleration information is stored in the storage unit (64) according to at least one of a moving direction and a position of the first stage (WS) and the second stage (RCS, RFS). .
Further, it is preferable that the acceleration information is updated by automatic learning during operation of the first stage (WS) and the second stage (RCS, RFS), and is stored in the storage unit (64).
In addition, the stage control device of the present invention is characterized in that the first control unit (52, 54) includes a feedback control system using a detection signal output from the position detection unit (32).
Further, the stage control device of the present invention is characterized in that the first control unit (52, 54) includes a feedforward control system using a target position of the first stage (WS).
Furthermore, the stage control device of the present invention further includes a stage position detection unit (35, 37) for detecting a position of the second stage (RCS, RFS), and the second control unit (57, 59, 62) And a feedback control system using detection signals (FS2, FS3) output from the stage position detection units (35, 37).
In order to solve the above problems, an exposure apparatus of the present invention transfers a mask stage (RCS, RFS) holding and moving a mask (R) on which a pattern is formed, and a pattern of the mask (R). A substrate stage (WS) that holds and moves the photosensitive substrate (W); and a stage control device (33) that controls the substrate stage (WS) and the mask stage (RCS, RFS) to move synchronously. In the exposure apparatus, the stage control device (33) generates a control signal indicating a thrust of the substrate stage (WS) according to a target position of the substrate stage (WS). ), A position detector (32) for detecting the position of the substrate stage (WS), and a detection signal output from the position detector (32). A second control unit (57, 59, 62) that uses the target position of S) and generates a control signal indicating the thrust of the mask stage (RCS, RFS), and a signal previously output from the position detection unit (32). A storage unit (64) for storing acceleration information indicating the acceleration of the mask stage (RCS, RFS) obtained based on the obtained signal, and the acceleration information stored in the storage unit (64). An auxiliary control unit (65) for performing feedforward control on the second control unit (57, 59, 62) is provided.
In order to solve the above problem, an exposure apparatus according to the present invention includes a mask stage (RCS, RFS) that moves while holding a mask (R) on which a pattern is formed, and a pattern of the mask (R) that is transferred. A substrate stage (WS) that holds and moves the photosensitive substrate (W) to be moved, and a stage controller (33) that controls the substrate stage (WS) and the mask stage (RCS, RFS) to move synchronously. The mask stage (RCS, RFS) includes a mask coarse movement stage (RCS) and a mask fine movement stage (RFS), and the stage control device (33) controls the substrate stage (WS). A) a controller that generates a control signal indicating a thrust of the substrate stage (WS) in accordance with a target position of the substrate stage (WS); A coarse movement control unit (57, 59) for generating a control signal indicating a thrust of the mask coarse movement stage (RCS) according to a target position where the mask stage (RCS, RFS) to be obtained is obtained from a position; A position detector (32) for detecting a position of the substrate stage (WS); and a detection signal output from the position detector (32) as a target position of the mask fine movement stage (RFS). A fine movement control unit (62) for generating a control signal indicating a thrust of the (RFS), and an acceleration of the mask fine movement stage (RFS) obtained based on a signal previously output from the position detection unit (32). A storage unit (64) for storing the acceleration information shown in the table, and a feedforward to the fine movement control unit (62) using the acceleration information stored in the storage unit (64). It is characterized in that it comprises an auxiliary control unit for de control and (65).
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a stage control device and an exposure apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view showing a configuration of an exposure apparatus according to an embodiment of the present invention. In the present embodiment, a step-and-scan type reduction projection type exposure apparatus will be described as an example. In the following description, the XYZ rectangular coordinate system shown in FIG. 1 is set, and the positional relationship of each member will be described with reference to the XYZ rectangular coordinate system. In the XYZ orthogonal coordinate system, the Y axis and the Z axis are set so as to be parallel to the paper surface, and the X axis is set so as to be perpendicular to the paper surface. In the XYZ coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set vertically upward.
[0019]
In FIG. 1, a base member (base or surface plate) 13 is provided on an installation surface 11 via four (only two are shown in FIG. 1) vibration damping devices (anti-vibration mechanisms) 12. The vibration isolator 12 is disposed near each of the four corners of the base member 13 and is not particularly limited. For example, a passive type including a pneumatic damper or a mechanical damper having a compression coil spring in a damping liquid is used. An active type having an actuator displaced so as to suppress the vibration based on a detection signal from a vibration detector (not shown) provided on the base member, or an active type having both of them is used. . The base member 13 is made of a highly rigid member such as stone, ceramics, or iron.
[0020]
A first column 15 holding a projection optical system 14 is provided above the base member 13, and a second column (base or surface plate) 16 is provided above the first column 15. I have. On the second column 16, a reticle coarse movement stage unit RCS and a reticle fine movement stage unit RFS for moving a reticle R as a mask on which a circuit pattern is formed are provided. Further, on the base member 13, a substrate stage for moving a wafer W as a photosensitive substrate or a wafer stage unit WS as a first stage is provided. As a result, the reticle R and the wafer W are planes having different positions in the direction (Z direction in FIG. 1) along the optical axis of the projection optical system 14, and are two-dimensional in a plane orthogonal to the optical axis. (X direction and Y direction).
[0021]
In the present embodiment, since the scanning direction of the exposure apparatus is set in the Y direction, drive control of the reticle R and the wafer W in the Y direction will be mainly described. The control of the positioning of the reticle R and the wafer W in the X direction and the adjustment of the rotation direction (θ direction) about the Z axis and the inclination angle with respect to the XY plane can be easily carried out as usual, and the description thereof will be omitted.
[0022]
The wafer stage unit WS includes a stator 17, a movable member 18 movable in the Y direction with respect to the stator 17, and a stage 19 mounted on the movable member 18. The stator 17 and the cooperating mover 18 may be provided by a linear motor. In particular, in the present embodiment, the stator 17 is provided movably in the Y direction on the base member 13 by a slide mechanism 20 such as an air bearing. The stator 17 may be fixed on the base member 13. The wafer W having the upper surface coated with the photosensitive agent is held on the stage 19 by, for example, sucking and sucking the entire back surface. Although the moving element 18 and the stage 19 are shown as separate members in FIG. 1, they may be provided by a common member.
[0023]
The reticle coarse movement stage unit RCS includes a stator 21, a movable member 22 movable in the Y direction with respect to the stator 21, and a stage 23 mounted on the movable member 22. The stator 21 and the cooperating mover 22 can be provided by a linear motor. In particular, in this embodiment, the stator 21 is provided movably in the Y direction on the second column 16 by a slide mechanism 24 having an air bearing or the like. The stator 21 may be fixed on the second column 16. Although the movable element 22 and the stage 23 are shown as separate members in FIG. 1, they may be provided by a common member.
[0024]
Reticle fine movement stage unit RFS is provided on stage 23 of reticle coarse movement stage unit RCS. The reticle fine movement stage unit RFS includes a stator 25, a movable member 26 provided to be movable in the Y direction with respect to the stator 25, and a stage 27 mounted on the movable member 26. The stator 25 and the cooperating mover 26 may be provided by a linear motor. In this embodiment, the stator 25 is fixed on the stage 23. Further, in FIG. 1, the moving element 26 and the stage 27 are illustrated as separate members, but they may be provided by a common member. The stage 27 has a function of holding a reticle R on which a pattern to be transferred is formed, with its pattern forming surface facing downward, in the vicinity of its peripheral portion by suction. The reticle coarse movement stage unit RCS corresponds to a mask coarse movement stage according to the present invention, and the reticle fine movement stage unit RFS corresponds to a mask fine movement stage according to the present invention. It corresponds to the mask stage or the second stage according to the invention.
[0025]
A third column 29 is provided on the second column 16. In the third column 29, light emitted from a light source such as an excimer laser (not shown) is converted into predetermined illumination light and guided to the reticle R. Optical system 30 is attached.
[0026]
A movable mirror 31 is attached to one end of the stage 19 for holding the wafer W, and a laser interferometer 32 as a position detector is provided in the first column 15 so as to correspond to the movable mirror 31. The laser interferometer 32 and the movable mirror 31 measure the position of the stage 19 in the Y direction at a predetermined resolution (for example, about 0.001 μm). The measured values are supplied to a control device 33 which can be provided by computer hardware and software, and the wafer stage unit WS is controlled based on the measured values, thereby accelerating, decelerating, and moving the stage 19 during scanning. Positioning is performed.
[0027]
A movable mirror 34 is mounted on the stage 23 for the reticle fine movement stage unit RFS, and a laser interferometer 35 as a stage position detector is mounted on the third column 29 so as to correspond to the movable mirror 34. I have. The position of the stage 23 in the Y direction is measured with a predetermined resolution (for example, about 0.001 μm) by the laser interferometer 35 and the moving mirror 34. The measured value is supplied to the control device 33, and the reticle coarse movement stage unit RCS is controlled based on the measured value, whereby the stage 23 is accelerated, decelerated, and moved and positioned for scanning.
[0028]
A movable mirror 36 is mounted on the stage 27 holding the reticle R, and a laser interferometer 37 as a stage position detector is provided on the third column 29 so as to correspond to the movable mirror 36. The laser interferometer 37 and the movable mirror 36 measure the position of the stage 27 in the Y direction at a predetermined resolution (for example, about 0.001 μm). The measured value is supplied to the control device 33, and the reticle fine movement stage unit RFS is controlled based on the measured value, so that the stage 27 is accelerated, decelerated, and moved and positioned for scanning.
[0029]
The illumination optical system 30 illuminates the rectangular pattern area of the reticle R from above with illumination light extending in a cross-sectional slit shape (rectangular shape) in a direction (X direction) orthogonal to the scanning direction (Y direction) during scanning exposure. I do. The illumination area on the reticle R of the slit-shaped illumination light linear in the X direction is located at the center of the circular visual field on the object plane perpendicular to the optical axis of the projection optical system 14, and has a predetermined reduction magnification β In the embodiment, an image of a part of the pattern of the reticle R in the illumination area is projected onto the wafer W at a predetermined resolution via the 1/4) projection optical system 14. As the projection optical system 14, one that projects a reduced inverted image of a pattern formed on the pattern surface of the reticle R onto the wafer W is used.
[0030]
At the time of scanning exposure, an exposure start command is sent from the control device 33 to the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS, and in response, the reticle R is moved in the + Y direction at the speed Vm. The wafer W is moved by scanning, and in synchronization with this, the wafer W is moved by scanning in the −Y direction at a speed Vw (= β · Vm). The reticle R may be moved in the −Y direction at the same speed ratio, and the wafer W may be moved in the + Y direction.
[0031]
At this time, focusing on the reticle coarse movement stage unit RCS, the reaction force acts on the stator 21 with the acceleration or deceleration of the movable element 22 and the stage 23, and the stator 21 is moved by the slide mechanism 24 in this embodiment. Since the movable member 22 is movable with respect to the two columns 16, the stator 21 attempts to move in the direction opposite to the moving direction of the movable member 22. In order to prevent the influence of the reaction force generated thereby, a reaction frame mechanism is employed.
[0032]
The reaction frame mechanism includes a reaction frame 38 provided independently of the second column 16 (therefore, the base member 13) and a reaction force that is provided on the reaction frame 38 and acts on the stator 21 by the movement of the stage 23. A reaction force device for generating a canceling force. Particularly, in this embodiment, a passive type reaction frame mechanism is adopted, and the reaction force device is provided by a reaction bar 39 made of an elastic body or a rigid body connecting the stator 21 and the reaction frame 28.
[0033]
Thereby, the reaction force accompanying the acceleration or deceleration of the stage 23 is released to the installation surface 11 via the reaction bar 39 and the reaction frame 38, and a certain exposure accuracy is ensured. Note that an active type reaction frame mechanism may be configured by providing an actuator that can electrically control the expansion and contraction of the reaction bar 39 in the middle thereof. Similarly, a reaction frame mechanism may be applied to wafer stage unit WS.
[0034]
FIG. 2 is a sectional view of a linear motor applicable to the exposure apparatus shown in FIG. This linear motor has a stator S and a movable element M that moves with respect to the stator S. When this linear motor is applied to the reticle coarse movement stage unit RCS (see FIG. 1), the stator S constitutes a part of the stator 21 shown in FIG. 1, and the mover M is shown in FIG. Of the moving element 22. The stator S includes a frame 40, a coil 41 fixed to the frame 40, and a cover 42 made of a metal plate fixed to the frame 40 and covering the coil 41. The mover M includes a permanent magnet for obtaining thrust in cooperation with the coil 41.
[0035]
The driving force of the wafer stage unit WS and the driving force of the reticle coarse movement stage unit RCS are provided by a linear motor having substantially the same configuration as that shown in FIG. In the present embodiment, in consideration of the features of the linear motor having the same characteristics, the control device 33 quickly and accurately corrects a synchronization error between the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS. The control to cancel is performed.
[0036]
Next, a control device 33 as a stage control device according to an embodiment of the present invention will be described. FIG. 3 is a block diagram showing a configuration of the control device 33 which is a main part of the stage control device according to one embodiment of the present invention. As shown in FIG. 3, the control device 33 includes a target position generator 50 that generates a reference signal RS1 that gives a target position of the wafer W or the stage 19 (see FIG. 1) of the wafer stage unit WS, and a target position generator 50. Stage control unit 33a that drives wafer stage unit WS based on reference signal RS1 output from, reticle coarse movement stage control unit 33b that drives reticle coarse movement stage unit RCS based on reference signal RS1, and wafer stage A reticle fine movement stage control section 33c for driving reticle fine movement stage RFS based on feedback signal FS1 in control section 33a;
[0037]
The wafer stage control unit 33a includes an arithmetic unit 51, a PID type controller 52, an adder 53, and a controller 54. The calculation unit 51 outputs a deviation signal ES1 corresponding to the difference between the reference signal RS1 output from the target position generator 50 and the feedback signal FS1 output from the laser interferometer 32. The position of the stage 19 of the wafer stage unit WS is detected by the laser interferometer 32 (see FIG. 1), and as a result, a feedback signal FS1 is generated.
[0038]
The PID type controller 52 generates a control signal CS1 relating to the thrust of the wafer stage unit WS based on the input deviation signal ES1. The controller 54 outputs a control signal DS1 related to the thrust of the wafer stage unit WS based on the reference signal RS1 output from the target position generator 50, and performs feedforward control. Here, the feedforward control using the controller 54 is performed in order to keep the time required for positioning the wafer stage unit WS and the time to reach the set speed within the time specified in the specification, and the synchronization accuracy is specified in the specification. This is for keeping the synchronization accuracy within the above. Adder 53 adds control signal CS1 output from PID type controller 52 and control signal DS1 output from controller 54, and outputs control signal CS10 that is actually given to wafer stage unit WS.
[0039]
As described above, the wafer stage control unit 33a includes the feedback control system using the feedback signal FS1 output from the laser interferometer 32 and the feedforward control system using the reference signal RS1 for giving the target position of the wafer stage unit WS. And Note that the PID type controller 52 and the controller 54 correspond to a first control unit or a control unit according to the present invention.
[0040]
The reticle coarse movement stage control unit 33b includes a conversion circuit 55, a calculation unit 56, a PID type controller 57, an adder 58, and a controller 59. Conversion circuit 55 converts reference signal RS1 according to a predetermined rule and outputs reference signal RS2. For example, the conversion circuit 55 provides a four-fold proportional operation according to the projection magnification (1/4) of the projection optical system 14 (see FIG. 1). The operation unit 56 outputs a deviation signal ES2 corresponding to the difference between the reference signal RS2 output from the conversion circuit 55 and the feedback signal FS2 output from the laser interferometer 35. The position of the stage 23 of the reticle coarse movement stage unit RCS is detected by the laser interferometer 35 (see FIG. 1), and as a result, a feedback signal FS2 is generated.
[0041]
The PID type controller 57 generates a control signal CS2 relating to the thrust of the reticle coarse movement stage unit RCS based on the input deviation signal ES2. Controller 59 outputs a control signal DS2 related to the thrust of reticle coarse movement stage unit RCS based on reference signal RS2 output from conversion circuit 55, and performs feedforward control. Here, feedforward control of reticle coarse movement stage unit RCS using controller 59 is performed so that the time required for positioning reticle coarse movement stage unit RCS and the time required to reach the set speed are within the time specified in the specification. , And the synchronization accuracy are within the synchronization accuracy specified in the specification. Adder 58 adds control signal CS2 output from PID type controller 57 and control signal DS2 output from controller 59, and outputs control signal CS20 that is actually provided to reticle coarse movement stage unit RCS.
[0042]
As described above, reticle coarse movement stage control unit 33b, like wafer stage control unit 33a, controls the feedback control system using feedback signal FS2 output from laser interferometer 35 and the target position of wafer stage unit WS. And a feedforward control system using a reference signal RS2 obtained by converting a reference signal RS1 to be supplied by a conversion circuit 55. The PID type controller 57 and the controller 59 correspond to a part of the second control unit or the coarse movement control unit according to the present invention.
[0043]
The reticle fine movement stage controller 33c includes a conversion matrix circuit 60, a calculator 61, a PID type controller 62, an adder 63, an acceleration table 64, and a zero phase filter 65. The conversion matrix circuit 60 converts a feedback signal FS1 output from the laser interferometer 32 provided for the wafer stage unit WS according to a predetermined rule, and outputs a reference signal RS3 indicating a target synchronization position. The operation unit 61 outputs a deviation signal ES3 according to the difference between the reference signal RS3 output from the conversion matrix circuit 60 and the feedback signal FS3 output from the laser interferometer 37.
[0044]
The PID type controller 62 generates a control signal CS3 relating to the thrust of the reticle fine movement stage unit RFS based on the input deviation signal ES3. Note that the PID type controller 62 corresponds to a part of the second control unit or the fine movement control unit according to the present invention. The acceleration table 64 stores a time relative to the feedback signal FS1 output from the laser interferometer 32 when the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS were previously operated in synchronization. The acceleration information obtained by performing the differentiation twice is stored in a table format. Note that this acceleration table is realized by a semiconductor storage device such as a RAM (Random Access Memory) or a magnetic storage device such as a hard disk, or other storage devices.
[0045]
Here, the acceleration information stored in the acceleration table 64 is preferably acceleration information obtained during the previous operation, but is not necessarily limited to this acceleration information, and may be any acceleration information obtained during the previous operation. good. Further, the wafer stage unit WS acceleration may change for each scanning direction (moving direction of the wafer stage unit WS and moving direction of the reticle coarse moving stage unit RCS and reticle fine moving stage unit RFS) in the apparatus configuration. It is preferable to store the acceleration information in the acceleration table 64 every time.
[0046]
Further, since the wafer stage unit WS needs to arrange the shot area where the pattern of the reticle R is to be transferred in the projection area of the projection optical system 14, the wafer stage unit WS is located at the position of the shot area where the pattern is to be transferred in the wafer W Accordingly, the acceleration of wafer stage unit WS may change. Therefore, it is preferable to store acceleration information in the acceleration table 64 for each shot area position (the position of the wafer stage unit WS) in the wafer W where a pattern is to be transferred. Note that the readability table 64 corresponds to a storage unit according to the present invention.
[0047]
The zero-phase filter 65 corresponds to an auxiliary control unit of the present invention, and outputs a control signal DS3 related to the thrust of the reticle fine movement stage unit RFS using the previous acceleration information stored in the acceleration table 64 to perform feedforward control. . Here, the zero-phase filter (linear phase filter) 65 is for correcting a phase distortion of the acceleration information stored in the acceleration table 64. That is, as described above, since the acceleration information stored in the acceleration table 64 is obtained by performing the time differentiation twice on the feedback signal FS1 output from the laser interferometer 32, the wafer stage unit WS Unnecessary components due to vibrations, noise, and the like (this component contains many high-frequency components) are enlarged.
[0048]
When such unnecessary components are large, the settling time of the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS becomes long, and the synchronization accuracy deteriorates. If a low-pass filter that removes the high-frequency component from the acceleration information is used to remove the unnecessary high-frequency component, the high-frequency component is removed, but phase distortion occurs at the same time. Therefore, the reticle coarse movement stage unit RCS for the wafer stage unit WS Further, the followability of the reticle fine movement stage unit RFS cannot be improved. For this reason, in the present embodiment, feedforward control is performed using the zero-phase filter 65 that can remove unnecessary high-frequency components included in acceleration information without causing phase distortion.
[0049]
When the reticle fine movement stage unit RFS is controlled, feedforward control may be performed using the reference signal RS2 converted by the conversion circuit 55 provided in the reticle coarse movement stage control unit 33b. However, reticle fine movement stage control unit 33c converts reference signal RS3 obtained by converting feedback signal FS1 from laser interferometer 32 provided for wafer stage unit WS by conversion matrix circuit 60 to the target of reticle fine movement stage unit RFS. And position. Therefore, even if feedforward control is performed on the reticle fine movement stage control unit 33c that performs such control using the reference signal RS2, phase distortion occurs, so that synchronization accuracy cannot be improved.
[0050]
Here, characteristics of the zero-phase filter 65 will be described. The zero-phase filter is a filter that determines the value of the current sampling point based on the sampling points before and after the current sampling point, that is, the values at the past sampling points and the values at the future sampling points. This filter is represented by the following equation (1).
(Equation 1)

[0051]
In the filter represented by the equation (1), after performing the filtering process in the forward direction (time direction from the past to the future), the filtered data sequence is reversed, and the filtering is performed again. The data string obtained in this way has exactly zero phase distortion. Here, the zero-phase filter is a non-causal filter because the value at the future sampling point is used to obtain the value at the current sampling point.
[0052]
In the present embodiment, since such an acausal zero-phase filter 65 is used, laser interference during movement of the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS is performed. Feedforward control of reticle fine movement stage unit RFS cannot be performed using feedback signal FS1 output from total 32. Therefore, assuming that the movement operations of the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit WFS have reproducibility, laser interference caused when these stages were previously operated in synchronization with each other is assumed. Using the acceleration information obtained by performing the time differentiation twice on the feedback signal FS1 output from the total 32, the acceleration information is passed through the zero-phase filter 65 to obtain a control signal DS3 without phase distortion, and the reticle fine movement is performed. The feedforward control of the stage unit RFS is performed.
[0053]
As the zero-phase filter, an FIR filter (finite impulse response filter) and an IIR filter (infinite impulse response filter) can be designed. Here, the FIR filter has an advantage that the linear phase characteristic can be accurately realized, and the stability of the filter is always guaranteed. However, when a steep amplitude frequency characteristic (cutoff characteristic) is realized, the order of the filter is low. It is necessary to take large. On the other hand, the IIR filter has an advantage that a desired amplitude frequency characteristic can be realized with a low order, but the distortion of the group delay characteristic increases, and stability is not always guaranteed. In the present embodiment, it is preferable to use an FIR filter for improving synchronization accuracy.
[0054]
Here, the feedforward control of the reticle fine movement stage unit RFS using the acceleration table 64 and the zero-phase filter 65 is performed by setting the time required for positioning the reticle fine movement stage unit RFS and the time required to reach the set speed as specified in the specification. This is for keeping the synchronization accuracy within the synchronization accuracy specified in the specifications. The adder 63 adds the control signal CS3 output from the PID type controller 62 and the control signal DS3 output from the zero phase filter 65, and outputs a control signal CS30 that is actually given to the reticle fine movement stage unit RFS.
[0055]
As described above, the reticle fine movement stage control unit 33c is, like the reticle coarse movement stage control unit 33b, a feedback control system using the feedback signal FS3 output from the laser interferometer 37, and the wafer stage unit WS The acceleration information obtained by performing time differentiation twice on the feedback signal FS1 output from the laser interferometer 32 when the reticle coarse movement stage unit RCS and the reticle fine movement stage unit RFS are operated in synchronization is used. A feed-forward control system.
[0056]
The above-mentioned acceleration information may be any information obtained when the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS have been moved in the past (past) in synchronization. It is preferable that the information is updated by automatic learning during the operation (operation) of the exposure apparatus and is stored in the acceleration table 64. As the learning method used here, for example, a learning method using a genetic algorithm (Genetic Algorithm) or a learning method using a neural network can be used. Here, the genetic algorithm refers to the evolution of living organisms in which individuals that adapt to the environment survive through interaction with the population and the environment, inherited excellent traits between generations through crossing, and acquired new traits through mutations. An artificial model that simulates a mechanism. It is a model that simulates the process of adapting natural and artificial systems to the environment.
[0057]
The configuration of the control device 33 as the stage control device according to the embodiment of the present invention has been described above. Next, a simulation result of a feedforward control system including the zero-phase filter 65 will be described. FIG. 4 is a diagram showing a result of simulating the input / output characteristics of the zero-phase filter 65. In the present embodiment, a twentieth-order zero-phase filter 65 is designed, and a simulation result of the zero-phase filter 65 will be described.
[0058]
In the simulation results shown in FIG. 4, the horizontal axis represents time and the vertical axis represents acceleration. The curve labeled L1 shows the input signal of the zero phase filter 65, and the curve labeled L2 shows the output signal of the zero phase filter 65. The input signal L1 is a signal obtained by performing a predetermined process (for example, a process of quadrupling the value) on the feedback signal FS1 output from the laser interferometer 32 and performing a time differentiation twice on this signal. , Corresponds to a signal indicating acceleration information stored in the acceleration table 64. In FIG. 4, the value of the output signal L2 is multiplied by 1.05 in order to clearly distinguish the input signal L1 from the output signal L2.
[0059]
First, paying attention to the vertical axis direction, it can be seen that unnecessary components due to vibration of the wafer stage unit WS, noise, and the like are superimposed on the input signal L1. However, it can be seen that the output signal L2 having passed through the zero-phase filter 65 has a smooth curve with these unnecessary components removed. Next, paying attention to the horizontal axis direction, the time when the acceleration becomes a value that can be considered to be the maximum in the input signal L1 and the time when the acceleration becomes the maximum in the output signal L2 match, so that the input signal L1 and the output signal L2 It can be seen that there is no phase difference between the two.
[0060]
Next, simulation results of the case where the zero-phase filter 65 is provided and the case where a low-pass filter is provided instead of the zero-phase filter 65 will be described. FIG. 5 is a diagram illustrating simulation results when the zero-phase filter 65 is provided and when a low-pass filter is provided instead of the zero-phase filter 65. In FIG. 5, as in FIG. 4, the horizontal axis represents time, and the vertical axis represents acceleration.
[0061]
In FIG. 5, a curve denoted by L11 indicates an output signal of the zero-phase filter 65, and a curve denoted by L12 indicates an output signal of the low-pass filter. In FIG. 5, for comparison, an acceleration curve obtained by performing time differentiation twice on a reference signal RS1 indicating the target position of the wafer stage unit WS is shown, and is denoted by reference symbol L10. FIG. 6 is an enlarged view of the acceleration curve indicated by the symbol M in FIG. 5 near the local maximum value. FIG. 6 is an enlarged view near the local maximum value of the acceleration curve.
[0062]
First, paying attention to the vertical axis direction, both the output signal L11 of the zero-phase filter 65 and the output signal L12 of the low-pass filter have smooth curves, and even when the zero-phase filter 65 is used, the zero-phase filter 65 It can be seen that even when a low-pass filter is used in place of, unnecessary components due to the vibration of the wafer stage unit WS and noise are removed.
[0063]
Next, paying attention to the horizontal axis direction, the output signal of the low-pass filter has a phase lag with respect to the acceleration curve L10 for the wafer stage unit WS, as is apparent from FIG. You can see that. On the other hand, as can be seen from the enlarged views of FIGS. 5 and 6, the output signal L11 of the zero-phase filter 65 has the same phase as the acceleration curve L10 for the wafer stage unit WS, and no phase distortion occurs. I understand.
[0064]
As described above, the simulation results of the case where the zero-phase filter 65 is provided to control the reticle fine-movement stage unit RFS by feedforward control, and the case where the low-pass filter is provided instead of the zero-phase filter 65 to perform the feedforward control of the reticle fine-movement stage unit RFS explained. Next, feedforward control is performed via the zero-phase filter 65 using past acceleration information, and reticle fine movement is performed using a signal obtained by performing time differentiation twice on the reference signal RS1 of the wafer stage unit WS. A simulation result in the case where the stage unit RFS is subjected to feedforward control will be described.
[0065]
FIG. 7 shows a case where feedforward control of the reticle fine movement stage is performed by using a signal through the zero phase filter 65 using past acceleration information, and a case where feedforward control of the reticle fine movement stage is performed using the reference signal RS1 of the wafer stage unit WS. FIG. 9 is a diagram showing a simulation result when performing. FIG. 7A is a diagram showing the standard deviation of the synchronization error, and FIG. 7B is a diagram showing the distribution of the Fourier components when the curve shown in FIG. 7A is Fourier-transformed.
[0066]
In FIG. 7A, a curve denoted by reference numeral L21 indicates a standard deviation of a synchronization error when feedforward control of the reticle fine movement stage is performed by a signal through the zero-phase filter 65 using past acceleration information. A reference numeral L22 is a curve showing a standard deviation of a synchronization error when feedforward control of the reticle fine movement stage is performed using the reference signal RS1 of the wafer stage unit WS.
[0067]
From FIG. 7A, it can be seen that the standard deviation of the synchronization error is smaller in the curve labeled L21 than in the curve labeled L22. The smaller the standard deviation of the synchronization error, the higher the synchronization accuracy between the wafer stage unit WS and the reticle coarse movement stage unit RCS and the reticle fine movement stage unit RFS. Therefore, the feedforward control of the reticle fine movement stage unit RFS is performed through the zero-phase filter 65 using the past acceleration information as in this embodiment, rather than using the reference signal RS1 of the wafer stage unit WS. Higher synchronization accuracy can be obtained by feedforward control using a signal.
[0068]
In FIG. 7B, a curve denoted by reference numeral L31 is a diagram showing a distribution of a Fourier component when the curve denoted by reference numeral L21 in FIG. 7 is a diagram showing the distribution of Fourier components when the curve indicated by reference symbol L22 in FIG. 7A is subjected to Fourier transform. From FIG. 7B, it can be seen that the curve denoted by the symbol L31 has a small amplitude of the Fourier component over almost the entire frequency range shown in FIG. 7B. On the other hand, the curve denoted by the symbol L32 is a low frequency region (frequency f in FIG. 7B). ₁ ~ F ₂ In the vicinity frequency region), the Fourier component is particularly large, and a portion where the amplitude of the Fourier component increases and a portion where the amplitude of the Fourier component decreases as the frequency increases, appear periodically.
[0069]
When the amplitude of the Fourier component is high, one stage (eg, wafer stage unit WS) vibrates at a certain frequency with respect to the other stage (eg, reticle coarse movement stage unit RCS, reticle fine movement stage unit RFS). Therefore, in order to increase the synchronization accuracy, it is better that the amplitude of the Fourier component is small. As described above, from the result of the Fourier transform, it is possible to obtain higher synchronization accuracy by performing feedforward control using a signal that has passed through the zero-phase filter 65 using past acceleration information as in the present embodiment. I understand.
[0070]
In the above, the control characteristics in the case where the reticle fine movement stage unit RFS is subjected to the feedforward control by the signal through the zero phase filter 65 using the past acceleration information have been described. Next, the operation at the time of exposure will be briefly described. When the exposure operation is started, control device 33 increases the acceleration of wafer stage unit WS and reticle stage unit (reticle coarse movement stage unit RCS and reticle fine movement stage unit RFS).
[0071]
Specifically, a reference signal RS1 for giving a target position is generated from a target position generator 50 shown in FIG. 3, and a PID type controller 52 is generated based on the reference signal RS1 and a feedback signal FS1 output from the laser interferometer 32. Outputs a control signal CS1, and the controller 54 outputs a control signal DS1 for feedforward control based on the reference signal RS1. The control signal CS1 and the control signal DS1 are added by the adder 53 and supplied to the wafer stage unit WS as the control signal CS10 to accelerate the wafer stage unit WS.
[0072]
The reference signal RS1 is converted into a reference signal RS2 by the conversion circuit 55, and the PID type controller 57 outputs a control signal CS2 based on the reference signal RS2 and the feedback signal FS2 output from the laser interferometer 35, and , The controller 59 outputs a control signal DS2 for feedforward control based on the reference signal RS2. The control signal CS2 and the control signal DS2 are added by the adder 58 and supplied as a control signal CS20 to the wafer stage unit WS to accelerate the wafer stage unit WS.
[0073]
Further, the feedback signal FS1 of the laser interferometer 32 is converted into a reference signal RS3 by the conversion matrix circuit 60, and the PID type controller 52 performs control based on the reference signal RS3 and the feedback signal FS3 output from the laser interferometer 37. The signal CS3 is output. Further, acceleration information stored by performing an operation previously is output from the acceleration table 64 to the zero-phase filter 65, and a control signal DS3 for feedforward control is output from the zero-phase filter 65. Here, the acceleration information output from the acceleration table 64 is acceleration information corresponding to the position of the shot area in the wafer W where the pattern is to be transferred and the movement direction of the wafer stage unit WS and the reticle coarse movement stage unit RCS. is there.
[0074]
When the acceleration period ends and the speed of each of the wafer stage unit WS and the reticle coarse movement stage unit RCS and the reticle fine movement stage unit RFS becomes constant, the wafer is irradiated with slit-shaped illumination light onto the reticle R, The scanning unit moves the stage unit WS in the −Y direction at a speed Vw (= β · Vm) and scans and moves the reticle stage unit in the + Y direction at a speed Vm. Is transferred to a shot area set on the wafer W via When the transfer of the reticle pattern to one shot area is completed, the wafer stage unit WS and the reticle stage unit are decelerated to stop the irradiation of the reticle R with the illumination light.
[0075]
Next, control device 33 drives wafer stage unit WS to move the shot area where the next pattern is to be transferred to the vicinity of the projection area of projection optical system PL (the area where the pattern of reticle R is projected). Then, similarly to the above-described operation, the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RFS are accelerated to have a constant speed, and then the reticle R is irradiated with illumination light to emit light. Are sequentially transferred to the shot area. FIG. 8 is a diagram illustrating an example of the movement path of the wafer W with respect to the projection area during pattern transfer. As shown in this figure, when transferring the shot area SA, the wafer W moves at a constant speed along the Y direction (+ Y direction or -Y direction). On the other hand, when the exposure processing for one shot area is completed and the process moves to the next shot area to be subjected to the exposure processing, the step movement is performed in the X direction (or Y direction) while accelerating and decelerating. By repeating such an operation, exposure processing is performed on all shot areas set on the wafer W.
[0076]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be freely changed within the scope of the present invention. For example, in the above embodiment, the step-and-scan type exposure apparatus has been described as an example, but the present invention is also applicable to a step-and-repeat type exposure apparatus. Further, the light source is not limited to excimer lasers such as a KrF excimer laser (248 nm) and an ArF excimer laser (193 nm). ₂ Laser light emitted from a laser (157 nm), Kr ₂ Laser light emitted from a laser (146 nm), Ar ₂ Laser light emitted from a laser (126 nm), and further, charged particle beams such as X-rays and electron beams can be used.
[0077]
In the above embodiment, the controllers 52, 57, and 62 shown in FIG. 3 may be any of a PID type controller, a P (Proportional: proportional) type controller, and a PI (Proportional Integral: proportional integral) type controller. Further, the controllers 52, 57, and 62 may be robust controllers based on current control theory. Further, the control device 33 illustrated in FIG. 3 may be configured as hardware by an electronic circuit, or may be configured as software. When each block is configured by software, the function of each block is realized by the CPU (Central Processing Unit) executing a program that defines the function of each block.
[0078]
Next, a method for manufacturing a micro device using the exposure apparatus according to the embodiment of the present invention in a lithography process will be briefly described. FIG. 9 is a flowchart showing an example of a manufacturing process of a micro device (a semiconductor chip such as an IC or LSI, a liquid crystal panel, a CCD, a thin-film magnetic head, a micromachine, etc.). As shown in FIG. 9, first, in step S10 (design step), a function / performance design of a micro device (for example, a circuit design of a semiconductor device) is performed, and a pattern design for realizing the function is performed. Subsequently, in step S11 (mask manufacturing step), a mask (reticle) on which the designed circuit pattern is formed is manufactured. On the other hand, in step S12 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.
[0079]
Next, in step S13 (wafer processing step), using the mask and the wafer prepared in steps S10 to S12, an actual circuit or the like is formed on the wafer by a lithography technique or the like, as described later. Next, in step S14 (device assembling step), device assembly is performed using the wafer processed in step S13. Step S14 includes, as necessary, processes such as a dicing process, a bonding process, and a packaging process (chip encapsulation). Finally, in step S15 (inspection step), inspections such as an operation confirmation test and a durability test of the microdevice manufactured in step S14 are performed. After these steps, the microdevice is completed and shipped.
[0080]
FIG. 10 is a diagram showing an example of a detailed flow of step S13 in FIG. 9 in the case of a semiconductor device. In FIG. 10, in step S21 (oxidation step), the surface of the wafer is oxidized. In step S22 (CVD step), an insulating film is formed on the wafer surface. In step S23 (electrode forming step), electrodes are formed on the wafer by vapor deposition. In step S24 (ion implantation step), ions are implanted into the wafer. Each of the above steps S21 to S24 constitutes a pre-processing step in each stage of the wafer processing, and is selected and executed according to a necessary process in each stage.
[0081]
In each stage of the wafer process, when the above-mentioned pre-processing step is completed, the post-processing step is executed as follows. In this post-processing step, first, in step S25 (resist forming step), a photosensitive agent is applied to the wafer. Subsequently, in step S26 (exposure step: transfer step), the circuit pattern of the mask is transferred to the wafer by the lithography system (exposure apparatus) and the exposure method described above. Next, in step S27 (developing step: developing step), the exposed wafer is developed, and in step S28 (etching step), the exposed members other than the part where the resist remains are removed by etching. Then, in step S29 (resist removing step), unnecessary resist after etching is removed. By repeatedly performing these pre-processing steps and post-processing steps, multiple circuit patterns are formed on the wafer.
[0082]
By using the microdevice manufacturing method described above, the above exposure apparatus is used in the exposure step (step S26), the resolution can be improved by illumination light in the vacuum ultraviolet region, and the exposure amount can be controlled with high precision. As a result, a highly integrated device having a minimum line width of about 0.1 μm can be produced with a high yield.
[0083]
In addition, not only micro devices such as semiconductor elements, but also to manufacture reticles or masks used in light exposure apparatuses, EUV exposure apparatuses, X-ray exposure apparatuses, electron beam exposure apparatuses, etc. The present invention is also applicable to an exposure apparatus that transfers a circuit pattern to a silicon wafer or the like. Here, in an exposure apparatus that uses DUV (deep ultraviolet) or VUV (vacuum ultraviolet) light or the like, a transmission reticle is generally used, and quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride, quartz, or the like is used. In a proximity type X-ray exposure apparatus or electron beam exposure apparatus, a transmission type mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate. Such an exposure apparatus is disclosed in WO99 / 34255, WO99 / 50712, WO99 / 66370, JP-A-11-194479, JP-A-2000-12453, JP-A-2000-29202, and the like. .
[0084]
【The invention's effect】
According to the present invention, when feedforward control is performed on the second stage, acceleration information obtained based on a signal output from the position detection unit when the operation was previously performed is stored in the storage unit. Since the second stage is feedforward controlled using the information, there is an effect that the synchronization accuracy between the first stage and the second stage can be improved.
Further, by performing feedforward control on the second stage, the settling time between the first stage and the second stage can be shortened, so that there is an effect that the throughput can be improved.
[Brief description of the drawings]
FIG. 1 is a front view showing a configuration of an exposure apparatus according to an embodiment of the present invention.
FIG. 2 is a sectional view of a linear motor applicable to the exposure apparatus shown in FIG.
FIG. 3 is a block diagram showing a configuration of a control device 33 which is a main part of the stage control device according to one embodiment of the present invention.
FIG. 4 is a diagram showing a result of simulating input / output characteristics of a zero-phase filter 65;
FIG. 5 is a diagram illustrating simulation results when a zero-phase filter is provided and when a low-pass filter is provided instead of the zero-phase filter.
FIG. 6 is an enlarged view near a local maximum value of an acceleration curve.
FIG. 7 shows a case where feedforward control of a reticle fine movement stage is performed using a signal through a zero phase filter 65 using past acceleration information, and a case where feedforward control of a reticle fine movement stage is performed using a reference signal RS1 of a wafer stage unit WS. FIG. 9 is a diagram showing a simulation result when performing.
FIG. 8 is a diagram illustrating an example of a movement path of a wafer W with respect to a projection area during pattern transfer.
FIG. 9 is a flowchart illustrating an example of a manufacturing process of a micro device.
FIG. 10 is a diagram showing an example of a detailed flow of step S13 in FIG. 9 in the case of a semiconductor device.
FIG. 11 is a block diagram illustrating a configuration example of a conventional stage control device provided in a scanning exposure apparatus.
[Explanation of symbols]
32 laser interferometer (position detector)
33 Stage control device (control device)
52 PID type controller (first control unit, control unit)
54 controller (first control unit, control unit)
57 PID type controller (second control unit, coarse movement control unit)
59 controller (second control unit, coarse movement control unit)
62 PID type controller (second control unit, fine movement control unit)
64 acceleration table (storage unit)
65 Zero phase filter (auxiliary control unit)
FS1 Feedback signal (detection signal)
FS2 feedback signal (detection signal)
FS3 feedback signal (detection signal)
R reticle (mask stage)
RCS reticle coarse movement stage unit (second stage, mask stage, mask coarse movement stage)
RFS reticle fine movement stage unit (second stage, mask stage, mask fine movement stage)
W photosensitive substrate
WS wafer stage unit (first stage, substrate stage)

Claims (9)

In a stage control device that controls the second stage so as to move in synchronization with the movement of the first stage,
A first control unit that generates a control signal indicating a thrust of the first stage according to a target position of the first stage;
A position detector for detecting a position of the first stage;
A second control unit that uses a detection signal output from the position detection unit as a target position of the second stage and generates a control signal indicating a thrust of the second stage;
A storage unit that stores acceleration information indicating the acceleration of the second stage obtained based on a signal previously output from the position detection unit;
A stage control device, comprising: an auxiliary control unit that performs feedforward control on the second control unit using acceleration information stored in the storage unit. The auxiliary control unit includes a linear phase filter,
The stage control device according to claim 1, wherein the feed-forward control is performed by supplying acceleration information via the linear phase filter to the second control unit. The stage control device according to claim 1, wherein the acceleration information is stored in the storage unit according to at least one of a moving direction and a position of the first stage and the second stage. . The said acceleration information is updated by automatic learning during the driving | operation of the said 1st stage and a 2nd stage, and is memorize | stored in the said memory | storage part, The Claims 1 to 3 characterized by the above-mentioned. Stage control device. The stage control device according to claim 1, wherein the first control unit includes a feedback control system using a detection signal output from the position detection unit. The stage control device according to claim 1, wherein the first control unit includes a feedforward control system using a target position of the first stage. A stage position detection unit that detects a position of the second stage;
The stage control device according to claim 1, wherein the second control unit includes a feedback control system using a detection signal output from the stage position detection unit. A mask stage that moves while holding a mask on which a pattern is formed, a substrate stage that moves while holding a photosensitive substrate onto which the pattern of the mask is transferred, and controls so that the substrate stage and the mask stage move synchronously An exposure apparatus having a stage control device
The stage control device,
A first control unit that generates a control signal indicating a thrust of the substrate stage according to a target position of the substrate stage;
A position detection unit that detects a position of the substrate stage,
A second control unit that uses a detection signal output from the position detection unit as a target position of the mask stage and generates a control signal indicating a thrust of the mask stage;
A storage unit that stores acceleration information indicating the acceleration of the mask stage obtained based on a signal previously output from the position detection unit,
An exposure apparatus comprising: an auxiliary control unit that performs feedforward control on the second control unit using acceleration information stored in the storage unit. A mask stage that moves while holding a mask on which a pattern is formed, a substrate stage that moves while holding a photosensitive substrate onto which the pattern of the mask is transferred, and controls so that the substrate stage and the mask stage move synchronously An exposure apparatus having a stage control device
The mask stage has a mask coarse movement stage and a mask fine movement stage,
The stage control device,
A control unit that generates a control signal indicating a thrust of the substrate stage according to a target position of the substrate stage,
A coarse movement control unit that generates a control signal indicating a thrust of the mask coarse movement stage,
A position detection unit that detects a position of the substrate stage,
Using a detection signal output from the position detection unit as a target position of the mask fine movement stage, a fine movement control unit that generates a control signal indicating the thrust of the mask fine movement stage,
A storage unit that stores acceleration information indicating an acceleration of the mask fine movement stage obtained based on a signal previously output from the position detection unit,
An exposure apparatus comprising: an auxiliary control unit that performs feedforward control on the fine movement control unit using acceleration information stored in the storage unit.

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