JP2004259845A - Parameter adjustment method, object transfer method, aligner, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To optimize parameter which prescribes operation of equipment with superior precision at short time. <P>SOLUTION: In a step 111, value of evaluation function Φ with a term wherein information regarding operation result of equipment is made evaluation factor is computed every scheme of at least multiples of set points of two specific parameters. In a step 119, update is so performed that combination wherein the value of evaluation function Φ becomes minimum is made an optimum combination. In a step 129, optimum values contained in combination of optimum values are set in the equipment as the respective set points of specific parameters. As a result, optimum values of set points of a plurality of specific parameters can be automatically computed based on the evaluation function Φ which has the term wherein information regarding operation result of the equipment is made evaluation factor. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０１３０】
なお、上述の表１では、「〜回転速度」の単位を「ｒｐｓ」とし、「〜回転加速度」又は「〜回転減速度」の単位を「ｒｐｓｓ」としているが、「ｒｐｓ」は、１秒当たりのモータの回転数を意味し、「ｒｐｓｓ」は、「１秒当たりのモータの回転数の変化量」を意味する。
【０１３１】
また、センタテーブル３０の下降動作を規定するパラメータとしては、図１２（Ｂ）に示されるように、区間Ｌ４におけるセンタテーブル３０の加速度Ｐ_１、最高速度Ｐ_２、減速度Ｐ_３と、区間Ｌ５におけるセンタテーブル３０の下降速度Ｐ_４、減速度Ｐ_５と、区間Ｌ４における減速が終了した位置からセンタテーブル３０の真空保持を解除するセンタテーブル下降Ｚ位置（以下、「センタテーブルバキュームオフ位置」とする）までの距離Ｐ_６と、センタテーブルバキュームオフ位置オフセットＰ_７とがある。区間Ｌ４，Ｌ５の長さは、パラメータＰ_１〜Ｐ_７の設定値によって決定されるものである。以下の表２に、センタテーブル３０の下降動作についての装置パラメータを示す。なお、センタテーブル３０を下降させる駆動機構の実体はモータの回転により駆動するカム機構及びリンク機構であるため、表２においては、センタテーブル３０の加速度、速度、減速度についてのパラメータ名称は「〜モータ回転加速度」、「〜モータ回転速度」、「〜モータ回転減速度」と表現されている。
【０１３２】
なお、パラメータＰ_７のパラメータ名称が「ＣＴバキュームオフ位置オフセット」となっている理由は、搬入アーム３６のパラメータＰ_８が「搬入アームバキュームオフ位置オフセット」となっている上述した理由と同様であり、単に「搬入アーム３６」と「センタテーブル３０」との関係が、「センタテーブル３０」と「ウエハホルダ１８」との関係に変わっただけである。
【０１３３】
【表２】

【０１３４】
上述した搬送動作を規定する各パラメータＰ_１〜Ｐ_１０は、露光装置１００を実際に運用する前、すなわちウエハの搬送動作及び露光動作により露光工程を実行する前に、調整されている必要がある。そこで、本実施形態では、実際に露光装置１００が稼動可能となり、ウエハの投入が可能となった状態で、実際の運用を開始する前に、パラメータ調整方法としてのパラメータの自動調整工程を実行する。
【０１３５】
本実施形態では、投入するウエハの位置決め精度やウエハの搬送に要した時間を、パラメータを調整する際の尺度として用いる。ウエハの位置決め精度は、ウエハをステージに投入した後、ウエハホルダ１８上に保持されたウエハ上に形成されたマークの位置情報を、アライメント系ＡＬＧによって検出することによって検出可能である。例えば、投入するウエハが、すでに１層目の露光を終えているものであれば、そのウエハには前述したサーチアライメントマークＳＹＭ、ＳθＭが形成されており、前述と同様にアライメント系ＡＬＧによって、それらのマークの位置情報を撮像し、その位置情報に基づいて、ウエハの位置決め精度の尺度である、位置ずれ量（ΔＸ、ΔＹ）及び回転ずれ量（Δθ）を算出することができる。
【０１３６】
前述したように、位置ずれ量（ΔＸ、ΔＹ）及び回転ずれ量Δθの値が、あまり大きすぎると、アライメント系ＡＬＧの撮像視野内に検出対象のマークを収めることが困難となる。したがって、このような状況では、正確な露光を実施することが不可能となるため、ウエハの再投入などが必要になり、スループットが極端に低下してしまう。したがって、本実施形態では、以下の表３に示されるような、ウエハの位置ずれ量（ΔＸ、ΔＹ）及び回転ずれ量Δθの投入再現性（ΔＸ（３σ），ΔＹ（３σ），Δθ（３σ），（ΔＹ−Δθ）（３σ））や、ずれ量の最大値から最小値までの範囲（ΔＸ（Ｍａｘ−Ｍｉｎ），ΔＹ（Ｍａｘ−Ｍｉｎ），（ΔＹ−Δθ）（Ｍａｘ−Ｍｉｎ））を、ウエハ投入性能評価ファクタＦ_ｉ（ｉ＝１〜９）に含んでパラメータの調整を行う。なお、本実施形態においては、設計位置からのずれ量（ΔＸ、ΔＹ、Δθ）の投入再現性に基づいてパラメータ調整しているが、本発明はこれに限らず、例えば、設計位置に関係なく、単にウエハの投入位置（Ｘ、Ｙ、θｚ）の再現性に基づいてパラメータ調整しても良い。
【０１３７】
【表３】

【０１３８】
なお、Ｆ_９、すなわちウエハ投入時間は、ウエハステージＷＳＴがウエハ交換位置へ移動し、ウエハホルダ１８上のウエハＷを回収してから、搬入アーム３６が保持するウエハＷ’がウエハホルダ１８上に投入され、ウエハホルダ１８上への真空吸着が開始されるまでの時間である。
【０１３９】
本実施形態では、減衰最小二乗法を用いてパラメータを最適化する。具体的には、以下の式（１）に示すような評価ファクタＦ_ｉ（ｉ＝１〜ｍ、ここではｍ＝９）を含む項から成る評価関数Φを設定し、その評価関数Φの値が最小となったときの設定パラメータを、最適パラメータとして設定する。
【０１４０】
【数１】

【０１４１】
ここで、ｗ_ｉは、それぞれの評価ファクタに対する重みであり、
【０１４２】
【外１】

【０１４３】
は、各評価ファクタの目標値であり、予め設定されている値である。また、ΔＰ_ｊ（ｊ＝１〜ｎ、ここでは、ｎ＝７又は１０）は、各パラメータの変化量である。Ｄを含む項は、減衰最小二乗法を適用する場合に評価関数に組み込まれる項である。この項を評価関数に組み込んだ場合には、この項が、線形近似範囲を外れたときの解の飛びを防ぐいわゆるダンパの役割を果たすようになり、評価関数Φを最小にする解が大きく外れるのが防止される。したがって、以下ではこの項をダンピング項と称し、係数Ｄをダンピングファクタと称する。
【０１４４】
なお、評価関数Φは、以下の式（２）とするようにしても良い。
【０１４５】
【数２】

【０１４６】
式（２）は、ダンピング項だけが式（１）と異なる。すなわち、式（２）は、パラメータ毎に、その変化量に乗ずるダンピングファクタの値をそれぞれ異なる値に設定可能となっている。
【０１４７】
また、本実施形態では、逐次接近法によって、各パラメータの最適化を図る。この逐次接近法は、まず、パラメータの設定値の組合せとして数通りの値の組合せを設定し、その組合せ１つ１つを露光装置１００に順次設定する毎に、ウエハ投入を実行する。そして、そのときの実行結果に関する情報としてのウエハの位置決め精度（Ｆ_１〜Ｆ_８）や、ウエハ投入時間（Ｆ_９）を計測して前述の評価関数Φの値を算出し、その値が最も小さかったときのパラメータの設定値の組合せをその時点における最適解とする。さらに、その最適解を基準とするパラメータの設定値の新たな組合せそれぞれについて、ウエハ投入、実行結果の計測、評価関数Φの値の算出を行い、それらの中で評価関数Φの値が最小であり、かつその値が前回最小であった評価関数Φよりも最小であるパラメータの設定値の組合せがあれば、その組合せを新たな最適解とする処理を何回か繰り返し実行することによって、パラメータの設定値の組合せの真の最適解に逐次接近していこうとする方法である。
【０１４８】
以下、本実施形態の露光装置１００によるパラメータ調整動作を、主制御装置２０内のＣＰＵの処理アルゴリズムを簡略化して示す図１３に示されるフローチャートに沿って、適宜他の図面を参照しながら説明する。なお、以下の説明では、図１２（Ａ）及び表１に示されるパラメータを調整する場合について説明する。
【０１４９】
図１３に示されるように、まず、ステップ１０１において、調整するパラメータを選定する。図１２（Ａ）及び表１に示されるパラメータは、すべて一律にウエハの位置決め精度に寄与するものではない。例えば、図１２（Ａ）に示されるＰ_８（搬入アームバキュームオフ位置オフセット）や、区間Ｌ２におけるＰ_４（受け渡し時搬入アームモータ回転速度）は、ウエハの位置決め精度に最も影響を与えると考えられ、その他にもＰ_３、Ｐ_９、Ｐ_１０などは、ウエハの位置決め精度にかなり影響を与えると考えられ、Ｐ_１、Ｐ_２、Ｐ_５、Ｐ_６、Ｐ_７などは、ウエハの位置決め精度に与える影響が小さいと考えられる。
【０１５０】
ステップ１０１では、表１に示されるパラメータの中から調整するパラメータを幾つか選定（特定）する。すなわち、本実施形態では、表１に示されるパラメータすべて一度に調整するのではなく、調整するパラメータを選定する。このようなパラメータの選定は、そのパラメータの評価関数Φの値への寄与度（影響度）に応じて行われるのが望ましい。例えば、ウエハの受け渡し区間、すなわちパラメータ（Ｐ_３、Ｐ_４、Ｐ_８、Ｐ_９）は、他のパラメータよりも、評価関数Φの値に対する重要度が大きいと考えられるため、ここでは、パラメータ（Ｐ_３、Ｐ_４、Ｐ_８、Ｐ_９）を選択するものとする。なお、このようなパラメータ選定は、主制御装置２０に備えられた不図示のキーボードを介して行われても良いし、予め記憶装置２１内に各パラメータをその重要度に応じてグループ化しておき、主制御装置２０が、最も重要度の高いパラメータのグループを読み出すことによって行われるようにしても良い。後者の方が、作業者の労力を軽減することができるとともに、パラメータ調整動作に要する時間を短くすることができる。
【０１５１】
次に、ステップ１０３において、計測種別又は最適化ステップ数を指定する。計測種別とは、後述するラフ／ファイン計測モード及びファイン計測モードを指し、最適化ステップ数は、前述した逐次接近法における最適解への接近の回数を指す。
【０１５２】
このパラメータの最適化に用いられる評価関数Φにおける評価ファクタには、表３に示されるウエハの投入再現性（３σ）が含まれており、その投入再現性をデータとして算出するには、ウエハを複数回投入する必要がある。投入再現性のデータの信頼性は、ウエハの投入回数、すなわち計測回数が多ければ多いほど高まるが、計測回数が多ければ、それだけ投入再現性のデータを算出するのに時間を要することになる。そこで、本実施形態の露光装置１００では、始めはこのウエハの投入回数を少なくして、ウエハの投入再現性を比較的少ない投入回数で計測し、パラメータの最適解をラフに検出した後、次にウエハの投入回数を多くして、パラメータの最適解を精度良く求めるラフ／ファイン計測モードを用意している。このラフ／ファイン計測モードを採用するか、ファイン計測のみのモードを採用する否かは、不図示のキーボードを介して指定されるようにしても良いし、そのモードが予め装置パラメータとして設定されていて、主制御装置２０は、このパラメータを参照して、このラフ／ファイン計測を行うか否かを判断するようにしても良い。ラフ／ファイン計測が選択された（又は選択されていた）場合には、このステップ１０３において、例えば内部メモリ領域に割り当てられているラフ／ファイン計測内部フラグをオンする。なお、ラフ／ファイン計測モードがパラメータに設定されていなかった場合には、通常の所定投入回数による計測（すなわちファイン計測のみ）が行われるように、ラフ／ファイン計測内部フラグをオフする。ここでは、ラフ／ファイン計測モードが選択されたものとして話を進める。
【０１５３】
また、ステップ１０３では、前述した逐次接近法において、パラメータの設定値の最適解を逐次接近させる回数としての最適化ステップ数を指定する。ここでも、最適化ステップ数は、不図示のキーボードを介して設定されるようにしても良いし、装置パラメータとして記憶装置２１に規定されていて、主制御装置２０が、この装置パラメータの値を読み出すようにしても良い。
【０１５４】
次に、ステップ１０５において、ステップ１０１にて選択されたパラメータの境界条件を設定する。ステップ１０１において、前述のように、特定パラメータとして、パラメータ（Ｐ_３，Ｐ_４，Ｐ_８，Ｐ_９）が選択された場合、このステップ１０５では、これらのパラメータの設定値の境界条件を設定する。この境界条件により、パラメータの設定値の取りうる範囲が規定され、後述するパラメータの設定値の組合せなどは、すべてこの境界条件を上限下限とする範囲内で決定されるようになる。また、ここで、特定パラメータそれぞれについての所定の設定値を基準とする、特定パラメータの設定値の複数の組合せを決定する。この場合には、パラメータＰ_３，Ｐ_４，Ｐ_８，Ｐ_９の設定値の複数の組合せが算出される。例えば、パラメータＰ_３，Ｐ_４，Ｐ_８，Ｐ_９の所定の設定値をそれぞれ（３Ｄ，４Ｄ，８Ｄ，９Ｄ）とした場合、（３Ｄ，４Ｄ，８Ｄ，９Ｄ）を基準とする幾つかの設定値の組合せが決定される。例えば、（３Ｄ，４Ｄ，８Ｄ，９Ｄ）から所定値±ΔＴだけ異なる値（３Ｄ±ΔＴ，４Ｄ±ΔＴ，８Ｄ±ΔＴ，９Ｄ±ΔＴ）をパラメータの各組合せの要素として考えれば、（３Ｄ−ΔＴ，３Ｄ，３Ｄ＋ΔＴ）、（４Ｄ−ΔＴ，４Ｄ、４Ｄ＋ΔＴ）、（５Ｄ−ΔＴ，５Ｄ、５Ｄ＋ΔＴ）、（６Ｄ−ΔＴ，６Ｄ、６Ｄ＋ΔＴ）の中からそれぞれいずれか１つの設定値を選んだときの組合せ（例えば（３Ｄ＋ΔＴ、４Ｄ−ΔＴ、５Ｄ，６Ｄ−ΔＴ）という組合せ）の総数（_３Ｃ_１×４）だけ、パラメータの設定値の組合せを決定することができる。なお、所定の設定値としては、装置定数によって予め求められた設計値を用いれば良い。
【０１５５】
次に、ステップ１０７において、ダンピングファクタＤの値を設定する。このダンピングファクタＤについても、キーボードにより設定可能か、あるいは装置パラメータ化されていて、記憶装置２１に記憶されたその値を主制御装置２０が読み出すことによって設定可能となっているものとする。なお、この場合、評価関数Φとして式（１）を用いる場合には、ダンピングファクタＤが記憶装置２１から１つだけ読み出され、式（２）を用いる場合には、ステップ１０１で選定された各パラメータに対応するダンピングファクタが記憶装置２１から読みだされる。
【０１５６】
次に、ステップ１０９において、所定回数のウエハ投入を実行する。この所定回数も、キーボードにより入力された数値、あるいは予め装置パラメータとして設定されている数値が用いられる。本実施形態では、パラメータ調整において、ラフ／ファイン計測モードが用意されているため、ラフ計測時のウエハ投入回数と、ファイン計測時のウエハ投入回数とが、装置パラメータとして設定されているものとする。なお、ステップ１０３において、ラフ／ファイン計測モードが設定されていた場合には、まず、ラフ計測の際のウエハ投入回数が所定回数として設定される。
【０１５７】
このウエハ投入は、前述した図８（Ａ）〜図８（Ｄ）、図９（Ａ）〜図９（Ｃ）、図１０（Ａ）〜図１０（Ｄ）に示す動作と同様に実行され、サーチアライメント動作において、ウエハホルダ１８に保持されたウエハに対し、前述したサーチアライメントマークの検出と同様の動作で、そのときのウエハの位置決め精度の尺度である、位置ずれ量（ΔＸ、ΔＹ）及び回転ずれ量Δθがウエハ投入毎に算出される。
【０１５８】
次に、ステップ１１１において、そして、主制御装置２０は、所定回数のウエハ投入についてのそれぞれ位置ずれ量（ΔＸ、ΔＹ）及び回転ずれ量Δθに基づいて、表３に示されるウエハ投入評価ファクタＦ_ｉ（ｉ＝１〜９）を算出し、今回のパラメータの設定値の組合せにおける評価関数Φの値を算出し、記憶装置２１にその値を記憶する。なお、評価関数Φに含まれる前述のダンピング項の各パラメータの変化量ΔＰ_ｊは、まだ、各パラメータの設定値が初期値のままなので、ΔＰ_ｊの値をすべて０として評価関数Φの値を算出する。
【０１５９】
ステップ１１３において、パラメータの設定値のすべての組合せについて、評価関数Φの値を算出したか否か（すべての組合せを実行したか）を判断する。ここでは、まだ１つの組合せでしか評価関数Φを算出していないので、ここでの判断は否定され、ステップ１１５に進む。
【０１６０】
ステップ１１５においては、装置に設定するパラメータの設定値の組合せを、まだ評価関数Φの値が算出されていない組合せに変更し、ステップ１０９に戻る。
【０１６１】
以降、ステップ１１３において、パラメータの設定値のすべての組合せにおいて、評価関数Φの値が算出されたと判断されるまで、ステップ１０９→ステップ１１１→ステップ１１３→ステップ１１５の処理が繰り返し実行され、すべての組合せでの評価関数Φの値が、ステップ１１１において算出される。なお、ステップ１１１において評価関数Φを算出する際には、評価関数Φのダンピング項における各パラメータの変化量ΔＰ_ｊには、そのパラメータの前回の設定値と今回の設定値との差を設定していけば良い。
【０１６２】
ステップ１１３における判断が肯定された後、ステップ１１７において、パラメータの設定値のすべての組合せについてそれぞれ算出された評価関数Φの中で、最小の値となる組合せを抽出する。なお、ステップ１１３での判断が肯定されるまで繰り返し実行されるステップ１０９〜ステップ１１５の処理が第１工程に含まれる。
【０１６３】
次にステップ１１９において、今回のステップ１１７において抽出された組合せの評価関数Φの値が、これまでに抽出された組合せの評価関数Φの値よりも小さい場合には、パラメータの最適値の組合せ、すなわちパラメータ最適解を、今回のステップ１１７において抽出された組合せに更新する。なお、今回のステップ１１７における組合せの算出は１回目（１ステップ目）の算出であるため、ここでは、今回算出されたパラメータ最適解を設定し、ステップ１２１に移行する。
【０１６４】
次いで、ステップ１２１では、逐次接近処理がステップ１０３において設定された指定ステップ数（最適化ステップ数）分実行されたか否かを判断する。この指定ステップ数は、前述のようにパラメータの組合せの最適解に逐次接近するステップ数を示し、例えばこの指定ステップ数が５回であったとすると、ここでは、まだ１ステップしか実行していないので、判断は否定され、ステップ１２３に進む。なお、このステップ１１７→ステップ１１９→ステップ１２１が第２工程に含まれる。
【０１６５】
次に、ステップ１２３において、これまでに評価関数Φを算出したパラメータの設定値の組合せとは異なる新しい組合せを作成する。この新しい組合せは、前述のステップ１１９において更新（設定）されたパラメータの最適値の組合せを基準として作成される。例えば、ステップ１１９において更新（作成）されたパラメータの最適値の組合せを中心とした所定の範囲内の値の中から、適当に抽出された幾つかの値の組合せが、新たな設定値の組合せとして作成される。作成された組合せは、記憶装置２１に記憶される。ステップ１２３実行後、処理はステップ１０９に戻る。
【０１６６】
なお、本実施形態では、ステップ１２１で判断が否定されると、ステップ１２３実行後、処理はステップ１０９に戻るとしているが、ステップ１２１で判断が否定された場合には、ステップ１２３に進まずに、直接ステップ１０５に戻るようにしても良い。この場合には、ステップ１０５において、新たにパラメータ境界条件を設定しなおすことができるようになり、その後のステップ１０７において、ダンピングファクタも設定しなおすことができるようになるので、さらにきめ細かい調整を実現することができるようになる。しかし、本実施形態では、処理時間の短縮化の観点から、ステップ１２１において判断が否定された後は、ステップ１２３に進み、ステップ１０９に戻るものとした。
【０１６７】
以降、ステップ１１３における判断が肯定されるまで、ステップ１０９→ステップ１１１→ステップ１１３→ステップ１１５の処理が繰り返し実行され、すべての組合せでの評価関数Φの値が、ステップ１１１において算出される。
【０１６８】
ステップ１１３における判断が肯定された後、ステップ１１７において、すべての組合せについてそれぞれ算出された評価関数Φの中で、最小の値となる組合せを抽出する。
【０１６９】
次にステップ１１９において、今回のステップ１１７において抽出された組合せの評価関数Φの値の中に、これまでに抽出された組合せの評価関数Φの値よりも小さいものがある場合には、パラメータの最適値の組合せ、すなわちパラメータ最適解を、今回のステップ１１７において抽出された組合せに更新する。なお、今回のステップ１１７における組合せの算出は２回目（２ステップ目）の算出であるため、ここでは、前回（１回目）のステップ１１７で算出されたパラメータ最適解に対応する評価関数Φの値よりも、今回算出された評価関数Φの値が小さい場合には、パラメータ最適解を、今回のパラメータ最適解に更新する。
【０１７０】
次いで、ステップ１２１では、処理（逐次接近）がステップ１０３において設定された指定ステップ数分実行されたか否かを判断する。この最適ステップ数は、前述のようにパラメータの組合せの最適解に逐次接近するステップ数を示し、ここでは、まだ２ステップしか実行していないので、判断は否定され、ステップ１２３に進む。
【０１７１】
以降、ステップ１２１における判断が肯定されるまで、すなわち、指定ステップ分のパラメータ最適解への逐次接近が完了するまで、ステップ１０９→ステップ１１１→ステップ１１３→ステップ１１５のループ処理及びステップ１１７→ステップ１１９→ステップ１２１→ステップ１２３の処理が繰り返し実行され、ステップ１１９において、所定ステップ数のパラメータ最適解の逐次接近が実行される。
【０１７２】
次いでステップ１２５において、主制御装置２０は、これまでに算出したパラメータの全ての組合せに対応する評価関数Φの値を読み出し、現在のパラメータ最適解の評価関数Φの値が、それらの中で最小であるか否かを確認する。
【０１７３】
そして、ステップ１２７において、計測モードとして、ラフ／ファイン計測モードを選択しているのか否かを前述のラフ／ファイン計測内部フラグがオンとなっているか否かを参照することによって確認する。そして、現在ラフ計測しか実行されていない場合には、判断は肯定され、ステップ１０５に戻る。なお、計測モードがラフ／ファイン計測モードでなかった場合、又は、ラフ／ファイン計測モードであって、ファイン計測モードも終了した場合には、判断は否定され、ステップ１２９に移行する。なお、ここでは、まだラフ計測しか行われていないので、判断は否定され、ステップ１０５に戻る。
【０１７４】
以降再び、ファイン計測モード、すなわち、ウエハの投入回数がファイン計測の場合に設定された上で、ステップ１０５からステップ１２５までの処理が実行され、再びステップ１２７に至る。この場合、すでにファイン計測を行っているので、判断は否定され、ステップ１２９に進む。
【０１７５】
次いで、ステップ１２９において、最終的に求められたパラメータ最適解、すなわちパラメータの設定値の最適値を設定する（第３工程）。これにより、パラメータ（Ｐ_３、Ｐ_４、Ｐ_８、Ｐ_９）の最適値が、露光装置１００に実際に設定され、以降は、露光装置１００のウエハ投入は、この設定値で実行される。
【０１７６】
次いで、ステップ１３１において、パラメータを変更するか否かを判断する。ここでは、すべてのパラメータのうち、パラメータ（Ｐ_３、Ｐ_４、Ｐ_８、Ｐ_９）しか最適化されていないため、判断は肯定され、ステップ１０１に戻る。
【０１７７】
なお、本実施形態では、必ずしも表１に示される全てのパラメータの最適化を行う必要はなく、前述の影響度が高いパラメータだけ調整するようにしても良い。この場合には、判断は否定され、処理は終了する。
【０１７８】
ステップ１０１では、まだ選定されていないパラメータの中から、調整するパラメータ（例えば、パラメータＰ_１，Ｐ_２，Ｐ_５，Ｐ_６，Ｐ_７，Ｐ_１０）を選定し、以降、ステップ１０３〜ステップ１３１の処理を前述と同様に実行する。このようにして、すべてのパラメータの調整が完了すると、ステップ１３１における判断は否定され、処理が終了する。
【０１７９】
以上述べたパラメータ調整動作を、立ち上げ時又はメンテナンス時などにおいて実行することにより、ウエハ投入動作を規定するパラメータが最適に調整され、露光装置１００の運用後は、この最適に調整されたパラメータによって、図１０（Ａ）から図１０（Ｂ）に渡って示される搬入アーム３６の下降動作を実行することができるようになる。
【０１８０】
なお、図１２（Ｂ）及び表２に示されるセンタテーブル３０の各パラメータも、上述の搬入アーム３６の各パラメータと同様に、図１３に示されるフローチャートに従った上述の動作によってそれらの設定値の最適化を図ることができる。この場合にも、ステップ１０１において、全パラメータの中から、影響度の大きい順に、実際に最適化を実行するパラメータを選定する。例えば、図１２（Ｂ）において、ウエハの投入精度に最も影響を与えるパラメータは、Ｐ_４，Ｐ_６，Ｐ_７であると考えられるため、初回のステップ１０１では、それらのパラメータを選定し、以降のステップ１０１において、随時他のパラメータを選定していけば良い。
【０１８１】
以上詳細に説明したように、本実施形態では、ステップ１１１において、少なくとも２つの特定パラメータの設定値の複数の組合せ毎に、露光装置１００の動作結果に関する情報を評価因子とする項を有する評価関数Φの値を算出する。そして、ステップ１１７において、例えば、その評価関数の値が、例えば最小となる組合せを、最適な組合せとして決定し、その最適値の組合せに含まれる最適値を、前記特定パラメータのそれぞれの設定値として露光装置１００に設定する。すなわち、本実施形態のパラメータ調整方法を実行すれば、露光装置１００の動作結果に関する情報を評価因子とする項を有する評価関数Φに基づいて、複数の特定パラメータの設定値の最適値を自動的に算出できるようになるため、短時間で精度良くパラメータの最適化を図ることができる。
【０１８２】
また、本実施形態では、ステップ１０９→ステップ１１１→ステップ１１３→ステップ１１７→ステップ１１９→ステップ１２１→ステップ１２３のループ処理、すなわち第２工程においてパラメータの最適値を真の最適解に逐次接近させる、いわゆる逐次接近法を用いることができるので、確実にパラメータの最適化を図ることができるようになる。
【０１８３】
したがって、上述のパラメータ調整動作実行後には、最適に調整されたパラメータに基づいてウエハを搬送して、ウエハステージＷＳＴ上に載置することができるため、ウエハの搬送を効率良く実行することができる。すなわち、本実施形態の露光装置１００では、パラメータが最適に調整されステージ上に保持されたウエハを露光することができるので、ウエハのショット領域の重ね合わせ精度を向上させることができるため、高精度で短時間な露光を実現することができる。
【０１８４】
また、本実施形態では、ダンピングファクタＤを含むダンピング項を有する評価関数Φに基づいてパラメータの最適化を図る、いわゆる減衰最小二乗法を用いている。このようにすれば、このダンピング項が、線形近似の範囲を外れた状態で最小二乗法を用いて求めたときに、その解が大きくはずれてしまうのを防止する役目を果たすようになるので、各パラメータの最適解を確実に求めることができるようになる。なお、本実施形態では、必ずしも減衰最小二乗法ではなく、最小二乗法を用いてもよい。この場合には、例えば、以下に示す式（３）を評価関数Φとして、図１３に示されるパラメータ調整動作を実行すれば良い。この式（３）には、ダンピング項はない。
【０１８５】
【数３】

【０１８６】
この式（３）の評価関数を用いれば、例えばステップ１２５は、パラメータ最適化前の初期状態での評価関数Φの値を読み出し、パラメータ最適化後の評価関数Φの値の方が小さくなっていることを確認するような方法とすることができる。また、本実施形態では、表３に示されるように、複数回のウエハ投入におけるサーチアライメントにおけるウエハの位置決め精度の再現性や、その範囲及びウエハ搬送時間などを、評価関数Φの評価因子Ｆ_ｉとしたが、本発明はこれに限定されるものではなく、ウエハアライメントによって算出されるウエハ座標系とステージ座標系とのずれ（ローテーション、直交度、Ｘ、Ｙ方向のスケーリング（倍率誤差）、Ｘ、Ｙ方向のオフセット）の再現性及び範囲を評価関数Φの評価因子とするようにしても良く、評価因子としては、ウエハの位置決め精度の再現性及び範囲を示すものであればどのようなものでも良い。
【０１８７】
また、本実施形態では、露光装置１００のウエハ投入の動作回数を少なくして、特定パラメータの最適値をラフに検出し、真の最適解にラフに接近した後、今度は、露光装置１００のウエハ投入の動作回数を多くして、高精度に各パラメータの設定値の真の最適解を求める。したがって、最初からウエハ投入の動作回数を多くして、その最適解を精査に検出するよりも、特定パラメータの最適解を求めるまでの装置の全体的な動作回数を少なくすることができるため、パラメータ調整に要する時間を短縮することができる。
【０１８８】
また、本実施形態では、複数のパラメータのうち、装置の動作結果に与える影響度の大きい順に、パラメータの数を適切に制限した状態でパラメータの調整が行われるので、各パラメータの最適化を無理なく調整することができるようになる。なお、パラメータの選定は、パラメータ（Ｐ_３、Ｐ_４、Ｐ_８、Ｐ_９）を必ず選択する必要はなく、パラメータ（Ｐ_４、Ｐ_８）だけであっても良いし、他の組合せであっても良い。また、本実施形態では、複数のパラメータ（Ｐ_３、Ｐ_４、Ｐ_８、Ｐ_９）の全ての設定値を変えた組合せを行ったが、例えば、パラメータＰ_８だけの最適値を設定するために、パラメータＰ_８の値のみを変更して、図１３に示されるパラメータ調整動作を実行しても良い。
【０１８９】
また、上記実施形態では、装置の立ち上げ時及びメンテナンス時等において行われるパラメータ調整動作について説明したが、本発明はこれに限定されるものではなく、例えば、装置の経時変化等により、ウエハの位置決め精度が悪化したときのために、実際に露光工程を実行する際に、同時にパラメータの最適化を行うようにしても良い。
【０１９０】
ところで、露光工程実行中に、図１３に示されるパラメータ調整動作を行っていたのでは、却って、スループットの低下を招く恐れもある。そこで、露光工程中にもパラメータの調整を行う場合には、以下に示すようにするのが望ましい。
【０１９１】
まず、上記実施形態とほぼ同様に、装置の立ち上げ時及びメンテナンス時において、パラメータの設定値の複数の組合せそれぞれについて複数回ウエハを投入した場合の投入結果の再現性及び範囲を求め、それらに基づいて、上述した式（１）〜式（３）のうちの少なくとも１つの評価関数Φの値を組合せ毎に算出する。そして、パラメータの設定値の変動と評価関数Φの値の変動との相関関係を示したテーブルを作成し、記憶装置２１に記憶しておく（テーブル作成工程）。
【０１９２】
そして、装置運用開始後は、上述した動作により、所定枚数（例えば１ロット）のウエハが搬送され、ステージ上に投入される毎に、算出される上述のサーチアライメントの結果等に基づく評価関数Φの値が悪化している（大きくなっている）か否か、例えば、所定の閾値よりも大きくなっているか否かを判断し、その判断が肯定されている場合には、記憶装置２１に記憶されている前述のテーブルに示されている評価関数Φと、パラメータの設定値の変動との相対関係を参照し、評価関数Φの値が小さくなる方向にパラメータの設定値を変更する。このようにすれば、搬入アーム３６によって所定枚数のウエハが搬送される毎に、ウエハの搬送結果に関する情報が検出され、そのときの評価関数Φの値が算出され、パラメータの設定値がその評価関数Φの値に基づいて最適値に調整される。すなわち、本発明では、パラメータの最適値が、装置の経時変化によって変化したとしても、そのパラメータの設定値を最適値に常に調整することができる。さらに、テーブルを参照するだけで、特定パラメータの最適値を求めることができるので、露光工程中においても、スループットを低下させることなく、パラメータを調整することができる。
【０１９３】
また、上記実施形態のパラメータ調整方法は、搬入アーム３６やセンタテーブル３０などのいわゆる搬送系の搬送動作を規定するパラメータの調整に有効なだけでなく、例えば、プリアライメント装置３２におけるウエハの向きや位置のずれを検出する検出動作を規定するパラメータの調整や、露光装置の露光動作を規定するパラメータ（例えば、スキャンスピード、ウエハＷに与えられる露光量、フォーカスオフセット等）の調整にも有効である。
【０１９４】
例えば、プリアライメント装置３２は、下方から照明された外縁部を、計測ユニット４０ａ〜４０ｃで計測して、ウエハの向き及び中心位置の位置ずれを検出するが、計測ユニット４０ａ〜４０ｃとしては、前述のように、一般にＣＣＤカメラ等の撮像装置が用いられ、前述の位置ずれの検出には、その撮像装置によって撮像された撮像データが用いられる。この撮像データは、ウエハへの照明のあたり具合によって、その内容が大きく変化するようになる。特に、ノッチを有する６時方向の撮像装置においては、撮像するウエハの外形が複雑であるため、光源５５であるＬＥＤの発光の状態（例えば、ウエハの外縁部の局所的な高輝度部の発生や、散乱光や、ノッチ部のもれ光）によって、ウエハの外形の計測精度が大きく変化する恐れがある。
【０１９５】
そこで、本発明は、プリアライメント装置３２において計測されるウエハの角度ずれや位置ずれの計測再現性（３σ）や計測値の範囲（最大値−最小値）を評価ファクタとする評価関数とし、図５に示す光源５５を構成する発光ダイオード（以下、「ＬＥＤ」と総称する）の電圧初期値やＬＥＤの点灯後から計測までの待ち時間（点灯後のＬＥＤの輝度が不安定なときでの計測を防ぐためのパラメータ）などを調整対象のパラメータとして、図１３に示すフローチャートと同様の動作でパラメータの調整を実行することにより、画像計測精度を向上させることもできる。すなわち、本発明は、物体の位置情報を検出する検出系の検出動作を規定するパラメータの最適化にも応用することができる。また、ウエハ搬送アーム５４にウエハを載置する前の、前述したウエハのＸ軸方向、Ｙ軸方向及びノッチの向きをラフに調整する機構のパラメータ調整にも、本発明を適用することができる。
【０１９６】
また、上記実施形態では、図１０（Ａ）〜図１０（Ｄ）に示される搬入アーム３６の下降動作及びセンタテーブル３０の下降動作を規定するパラメータの調整、すなわちウエハロード時の動作を規定するパラメータの調整について説明したが、本発明はウエハのアンロード動作を規定するパラメータの調整にも適用することができる。例えば、図９（Ｂ）から図９（Ｃ）に示されるセンタテーブル３０の上昇動作及び吸着解除動作や、搬出アーム５２のＹ軸方向の移動及び吸着開始動作などを規定するパラメータの調整にも本発明を適用することができる。このときには、例えば露光装置１００の搬出アーム５２からウエハを受け渡された基板処理装置におけるウエハの位置検出機構によって検出されるウエハの位置決め精度及びそこに至るまでの搬送時間等が評価関数の評価因子となる。
【０１９７】
また、上記実施形態では、実際に、露光装置１００にウエハ投入を行った場合の動作結果に基づいてパラメータの調整を行ったが、パラメータ調整は、露光装置１００の装置定数や設置条件などに基づいてコンピュータ上に構築される露光装置１００の数学モデルによってウエハの投入動作のシミュレーションを実行し、シミュレーションによって算出される、装置の動作結果に関する情報（表３に示される各評価ファクタＦ_ｉ）の推定値から評価関数Φを求め、パラメータの調整を行なうようにしても良い。
【０１９８】
また、上記実施形態では、評価関数Φにおける評価ファクタとして、サーチアライメントの計測結果を用いたが、本発明はこれに限定されるものではなく、例えば、前述のＥＧＡにおけるウエハ座標系とステージ座標系とのずれ（回転、オフセット、スケール）の再現性及び範囲などを評価ファクタとしても良い。
【０１９９】
また、上記実施形態では、ウエハの搬送動作を規定するパラメータの調整方法について述べたが、レチクルの搬送動作あるいは計測動作についても本発明を適用することができることがいうまでもない。
【０２００】
なお、ウエハのプリアライメント装置は、上記実施形態で説明したものに限らず、種々の形態のものを用いることができる。例えば、特開平９−３６２０２号公報の如く、ウエハステージＷＳＴ上に照明系を搭載し、ウエハステージＷＳＴが搬入アーム３６の下に来てから、ウエハステージＷＳＴ上に搭載した照明系を用いてプリアライメントを行うような構成にしても良い。あるいは、ウエハの上方より発光素子で照明し、ウエハの下方に受光素子を配置して透過光を検出するようにしても良い。このように、プリアライメント検出としては種々の手法を採ることができるが、いずれにしても露光動作が終了し、ウエハ交換のためウエハステージＷＳＴをウエハ交換位置に移動させ、アンロード作業を行うのと並行してプリアライメント計測が行える。
【０２０１】
このように、ウエハのプリアライメント装置などによって構成されるプリアライメント機構には、様々な形態のものが考えられる。例えば、図１４（Ａ）〜図１４（Ｃ）に示されるように、ウエハホルダに対して出没可能なセンタテーブル３０を設けずに、ウエハステージＷＳＴやウエハホルダ１８に、搬入アーム３６におけるフック部５０ａ〜５０ｃが通過可能な一対の凹溝３１ａ，３１ｂ及び切欠き部３０ａ〜３０ｂを形成し、搬入アーム３６と、ウエハステージＷＳＴの協調動作で、搬入アーム３６とウエハステージＷＳＴとを干渉させることなく、ウエハの受け渡しを行うようにしても良い。
【０２０２】
また、ウエハホルダに対し出没可能なセンタテーブル３０を設けた状態で、プリアライメント装置３２を設けずに、ウエハ搬送アーム５４からセンタテーブル３０に直接受け渡すような形態となっていても良い。いずれにしても、本発明によるウエハの投入動作を規定するパラメータの最適化により、各種搬送系の精度とスループットを両立するウエハの搬送を実現することが可能である。
【０２０３】
なお、本明細書において、「アーム」とは、物体としての基板（上記実施形態ではウエハ）の搬送時にその保持に用いられる部材を含む広い概念である。
【０２０４】
すなわち、上記実施形態では、評価関数Φの評価因子の値の検出系としてのアライメント系ＡＬＧとして、ＦＩＡ系の他にＬＳＡ（Ｌａｓｅｒ Ｓｔｅｐ Ａｌｉｇｎｍｅｎｔ）系などを適用することも可能である。ＬＳＡ系とは、レーザ光をマークに照射して、回折・散乱された光を利用して検出対象のマークの位置を計測する最も汎用性のあるセンサであり、従来から幅広いプロセスウエハに使用されている。また、この他、アライメント系ＡＬＧとして、例えばコヒーレントな検出光を検出対象のマークに照射し、そのマークから発生する２つの回折光（例えば同次数）を干渉させて検出するアライメントセンサを単独で、あるいは上記ＦＩＡ系、ＬＳＡ系などと適宜組み合わせて用いることは可能である。
【０２０５】
また、上記実施形態では、露光用照明光としてＫｒＦエキシマレーザ光（２４８ｎｍ）、ＡｒＦエキシマレーザ光（１９３ｎｍ）、ｇ線（４３６ｎｍ）、ｉ線（３６５ｎｍ）、Ｆ_２レーザ光（１５７ｎｍ）などを用いる場合について説明したが、これに限らず、銅蒸気レーザ、ＹＡＧレーザ、半導体レーザなどの高調波等を露光用照明光として用いることができる。
【０２０６】
また、上記実施形態の露光装置において、投影光学系は縮小系、等倍あるいは拡大系のいずれを用いても良いし、屈折系、反射屈折系、及び反射系のいずれであっても良い。
【０２０７】
なお、上記実施形態では、ステップ・アンド・スキャン方式の投影露光装置について説明したが、本発明は、ステップ・アンド・リピート型の投影露光装置の他、プロキシミティ方式の露光装置など他の露光装置にも適用できることはいうまでもない。
【０２０８】
また、本発明は、半導体製造用の露光装置に限らず、液晶表示素子などを含むディスプレイの製造に用いられる、デバイスパターンをガラスプレート上に転写する露光装置、薄膜磁気ヘッドの製造に用いられるデバイスパターンをセラミックウエハ上に転写する露光装置、及び撮像素子（ＣＣＤなど）、マイクロマシン、有機ＥＬ、ＤＮＡチップなどの製造に用いられる露光装置などにも適用することができる。また、ＥＵＶ光、Ｘ線、あるいは電子線及びイオンビームなどの荷電粒子線を露光ビームとして用いる露光装置に本発明を適用しても良い。
【０２０９】
また、半導体素子などのマイクロデバイスだけでなく、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などで使用されるレチクル又はマスクを製造するために、ガラス基板又はシリコンウエハなどに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（遠紫外）光やＶＵＶ（真空紫外）光など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、螢石、フッ化マグネシウム、又は水晶などが用いられる。また、プロキシミティ方式のＸ線露光装置、又は電子線露光装置などでは透過型マスク（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エハなどが用いられる。
【０２１０】
なお、上記実施形態では、本発明に係る搬送装置が露光装置に適用された場合について説明したが、これに限らず、本発明は、半導体処理の他の工程で用いられる種々の装置、例えば、検査装置に好適に適用でき、同様に位置決め精度を維持しつつ、スループットの向上を図ることができる。
【０２１１】
半導体デバイスは、デバイスの機能・性能設計を行うステップ、この設計ステップに基づいたレチクルを製作するステップ、シリコン材料からウエハを製作するステップ、前述した実施形態の露光装置によりレチクルのパターンをウエハに転写するステップ、デバイス組み立てステップ（ダイシング工程、ボンディング工程、パッケージ工程を含む）、検査ステップ等を経て製造される。
【０２１２】
【発明の効果】
以上説明したように、本発明のパラメータ調整方法によれば、短時間で精度良く、装置の動作を規定するパラメータの最適化を図ることができるという効果がある。
【０２１３】
また、本発明の物体搬送方法によれば、短時間で精度良く物体を搬送することができるという効果がある。
【０２１４】
また、本発明の露光装置によれば、露光精度を維持しつつ、スループットの向上を実現することができるという効果がある。
【０２１５】
また、本発明のプログラムによれば、短時間で精度良く、装置の動作を規定するパラメータの最適化を図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係る露光装置の概略構成を示す図である。
【図２】図２（Ａ）は、ウエハステージ及びウエハホルダを示す斜視図であり、図２（Ｂ）は、ウエハステージ及びウエハホルダを示す平面図であり、図２（Ｃ）は、ウエハステージ及びウエハホルダを−Ｙ側から見たときの図（一部断面）である。
【図３】ウエハのプリアライメントが行われている最中のウエハ搬送系の状態を示す図である。
【図４】ウエハ搬送系とプリアライメント系を示す斜視図である。
【図５】計測ユニットの内部構成を簡略化して示す図である。
【図６】図６（Ａ）は、８インチウエハにおける計測ユニットによる計測位置を示す図であり。図６（Ｂ）は、オリエンテーションフラットが設けられているウエハにおける計測ユニットによる計測位置を示す図である。
【図７】搬入アームを取り出して示す斜視図である。
【図８】図８（Ａ）〜図８（Ｄ）は、ウエハ搬送系及びウエハステージの動作を説明するための図（その１）である。
【図９】図９（Ａ）〜図９（Ｃ）は、ウエハ搬送系及びウエハステージの動作を説明するための図（その２）である。
【図１０】図１０（Ａ）〜図１０（Ｄ）は、ウエハ搬送系及びウエハステージの動作を説明するための図（その３）である。
【図１１】ウエハ上のサーチアライメントマークの形成位置を示す図である。
【図１２】図１２（Ａ）は、搬入アームの下降動作の速度分布を示す図であり、図１２（Ｂ）はセンタテーブルの下降動作の速度分布を示す図である。
【図１３】本発明の一実施形態に係る露光装置によるパラメータ調整動作を、主制御装置２０内のＣＰＵの処理アルゴリズムを簡略化して示すフローチャートである。
【図１４】ウエハステージ及びウエハホルダの変形例を示す斜視図である。
【符号の説明】
２０…主制御装置、３０…センタテーブル、３６…搬入アーム、１００…露光装置、ＡＬＧ…アライメント系、Ｗ…ウエハ、Ｗ’…ウエハ、ＷＳＴ…ウエハステージ。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a parameter adjustment method, an object transport method, an exposure apparatus, and a program, and more particularly, to a parameter adjustment method for adjusting set values of a plurality of parameters that define an operation of an apparatus, and an object using the parameter adjustment method. The present invention relates to a transport method, an exposure apparatus that exposes an object, and a program that causes a computer to execute a procedure for adjusting set values of a plurality of parameters that define an operation of the apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, or the like, a pattern formed on a mask or a reticle (hereinafter, collectively referred to as a “reticle”) is coated with a resist or the like via a projection optical system. There is used an exposure apparatus for transferring an image onto a substrate such as a wafer or a glass plate (hereinafter, also appropriately referred to as a “wafer”). In recent years, as an apparatus of this type, from the viewpoint of emphasizing throughput, a step-and-repeat type reduction projection exposure apparatus (so-called “stepper”) or a step-and-scan type scanning type apparatus which is an improvement of this stepper has been used. 2. Description of the Related Art Sequentially moving projection exposure apparatuses such as exposure apparatuses are relatively frequently used.
[0003]
In the lithography process, before the exposure process by the exposure apparatus as described above is performed, a resist coating process of applying a resist as a photosensitive agent on the wafer is performed, and after the exposure process is performed, exposure is performed. A development step of developing an image transferred onto the wafer is performed. Therefore, in order to improve the throughput in the entire lithography process, a coater / developer or the like including a resist coating device (that is, a coater) for applying a resist and a developing device (that is, a developer) that develops a wafer is used. It is desirable that the other substrate processing apparatus and the exposure apparatus are connected, for example, in-line, so that the wafer can be efficiently transferred between the apparatuses.
[0004]
On the other hand, in an exposure apparatus, in order to accurately transfer a pattern to a desired position on a wafer, a projection optical system that irradiates the wafer with exposure light via the pattern and a relative positional relationship during exposure of the wafer. Needs to be optimized. Therefore, in the exposure apparatus, before performing exposure, information on the orientation and position of the wafer is detected by a detection system having a fixed positional relationship with the projection optical system, and the wafer coordinate system determined by the orientation and position of the wafer is determined. And a stage coordinate system that defines the movement of the stage holding the wafer, and the direction and position of the wafer are corrected by moving the stage or the like so as to cancel the deviation.
[0005]
However, the detection range of the above-described detection system (that is, the detection visual field) has a limit, and the movement range of the stage that can correct the direction and position of the wafer also has a limit. Therefore, if the deviation between the wafer coordinate system and the stage coordinate system is too large, for example, the notch of the wafer is out of the above-described detection range, and it becomes difficult to detect the orientation and position of the wafer by the detection system. There is no guarantee that the direction of the wafer transferred by the transfer system is always in a fixed direction.If the wafer is held on the stage as it is transferred by the transfer system, the size of the deviation between the wafer coordinate system and the stage coordinate system In many cases, it is difficult to detect the orientation and position of the wafer by the detection system. In such a case, the wafer must be rearranged and the throughput is extremely reduced. In order to solve this inconvenience, the exposure apparatus detects the direction and position of the wafer transferred by the transfer system before holding the wafer on the stage, and detects the direction and position within a certain allowable range, that is, the above-described detection system. It is provided with a so-called pre-alignment device that adjusts to fall within the detection range.
[0006]
In an exposure apparatus having a pre-alignment apparatus, first, a wafer sent from another substrate processing apparatus is transferred to a wafer transfer system provided in the exposure apparatus, and then transferred by the wafer transfer system. The wafer is transferred from the wafer transfer system to an arm constituting a part of the pre-alignment apparatus.
[0007]
The pre-alignment apparatus detects the outer shape of the wafer by a wafer detection sensor constituting the pre-alignment apparatus while supporting the wafer on the arm, and based on the detection result, the orientation (ie, rotational displacement) and position of the wafer. (That is, the center position shift) is calculated. The arm is configured to be rotatable while supporting the wafer, that is, to be able to change the direction of the wafer, and the calculated rotational deviation of the wafer is corrected by the rotation of the arm, and The center misalignment is canceled by adjusting their relative positional relationship when transferring the wafer from the arm to the stage. That is, pre-alignment is performed in this manner.
[0008]
After the pre-alignment, the wafer is transferred from the arm to the stage. At this time, at the time of exposure, the stage immediately below the projection optical system moves to a position immediately below the arm, that is, a wafer exchange position, and the arm is lowered toward the stage, so that the wafer is transferred onto the stage. In order to avoid interference (contact) between the end of the arm and the stage during transfer, the stage is provided with a small table that can protrude from its surface. That is, when a wafer is delivered, the table is raised while the arm is lowered, the wafer is delivered from the arm to the table, and after the arm is retracted, the table receiving the wafer is lowered, Finally, the wafer is placed on the stage and held by, for example, vacuum suction or electrostatic suction. In addition, a vacuum suction mechanism or an electrostatic suction mechanism for suctioning the wafer is provided at the tip of the arm or the table, and the direction and position of the wafer are not shifted during the transfer of the wafer. The suction mechanism is operated to hold the wafer.
[0009]
[Problems to be solved by the invention]
In the exposure apparatus as described above, it is desirable to minimize the time required for transferring the wafer from the arm to the stage in order to improve the throughput. Therefore, the lowering speed of the arm and the lowering of the table to which the wafer has been transferred are desired. It is desirable to increase the wafer transfer speed such as the speed as much as possible. However, if the transfer speed of such a wafer is set too high, the force applied to the wafer at the time of transfer or transfer becomes large, and the suction force of the suction mechanism of the arm or the table cannot withstand those forces, and the wafer is not transferred. The possibility of deviation increases. This wafer shift becomes a shift between the wafer coordinate system and the stage coordinate system as it is. As described above, the exposure accuracy is reduced, and when the shift is extremely large, the throughput is also reduced.
[0010]
Further, when transferring the wafer from the arm to the table, if the timing for releasing the suction by the suction mechanism of the arm and the timing for starting the suction by the table are not appropriate, for example, the suction force applied simultaneously from both sides is weak. The wafer moves freely and shifts its position, or the suction force applied simultaneously from both sides is too strong, the wafer deforms elastically and vibrates due to the elastic force, and the vibration shifts the position of the wafer. There is a possibility that it will be lost. This wafer shift also results in a shift between the wafer coordinate system and the stage coordinate system. As described above, the exposure accuracy is reduced, and when the shift is extremely large, the throughput is also reduced.
[0011]
As described above, it is extremely difficult to realize high-precision exposure unless the transfer speed of the wafer and the timing for releasing / starting the suction of the wafer are properly adjusted. Further, even if the exposure apparatus has the same specifications, even if the operating characteristics are within the range of the apparatus adjustment standard, the operation characteristics are slightly different for each unit, so that the optimal transfer speed and the wafer suction level which do not impair the accuracy are obtained. Also, the timing of release / start differs for each machine (note that such a difference in the optimal value for each machine depends on various factors. For example, the transport system depends on the installation state of the device. A difference in relative parallelism with the destination is also considered as one of the factors.)
[0012]
Therefore, in such an exposure apparatus, factors relating to the wafer positioning time and the transfer time, such as the transfer speed of the wafer and the timing of releasing / starting the suction by the suction mechanism, are converted into apparatus parameters, and the apparatus is started up. It is desirable that these parameters can be adjusted and optimized at the time of maintenance and maintenance.
[0013]
However, there are many parameters that affect such wafer positioning accuracy and transfer time, and it is extremely difficult to optimize all of them. Therefore, optimization of those parameters depends on the adjustment ability of the operator. Is extremely difficult. For this reason, at present, these parameters can be further optimized depending on the machine, and although the carry-in time can be shortened, only a small number of parameters such as the position where the arm is released from suction can be adjusted for each machine, and the entire exposure In order to avoid a decrease in the yield of the apparatus, the setting values of a number of other parameters are set to a unit having the lowest performance among all the exposure apparatuses (a value common to the units). That is, the common setting of this parameter sacrificed the throughput of some units having relatively high performance.
[0014]
The present invention has been made under such circumstances, and a first object of the present invention is to provide a parameter adjustment method capable of optimizing parameters for defining an operation of an apparatus in a short time and with high accuracy. is there.
[0015]
A second object of the present invention is to provide an object transfer method capable of transferring an object in a short time and with high accuracy.
[0016]
A third object of the present invention is to provide an exposure apparatus that can improve the throughput while maintaining the exposure accuracy.
[0017]
It is a fourth object of the present invention to provide a program capable of causing a computer to execute a procedure for optimizing parameters for defining the operation of an apparatus in a short time and with high accuracy.
[0018]
[Means for Solving the Problems]
According to the first aspect of the present invention, a plurality of parameters (P ₁ Etc.) is a parameter adjustment method for adjusting the set value of each of the specific parameters based on a predetermined set value for each of at least two specific parameters selected from the plurality of parameters. Information about the operation result of the device when a plurality of combinations are sequentially set in the device is obtained, and the value of an evaluation function (Φ) having a term that uses the obtained information about the operation result as an evaluation factor is set for each of the combinations. A first step of calculating; a second step of obtaining an optimum combination of set values of the specific parameters based on the value of the evaluation function calculated for each of the combinations; an optimum included in the combination of the optimum values Setting a value in the device as a set value of each of the specific parameters.
[0019]
According to this, in the first step, for some combinations of the set values of at least two specific parameters, for each combination, the value of the evaluation function having a term using the information on the operation result of the device as an evaluation factor is determined. Is calculated. Then, in the second step, for example, a combination in which the value of the evaluation function is the smallest, for example, is determined as the optimal combination, and in the third step, the optimal value included in the combination of the optimal values is determined for each specific parameter. The values are set in the device as the respective set values. That is, if the parameter adjusting method of the present invention is executed, the optimum values of the set values of the plurality of specific parameters are automatically calculated based on the evaluation function having the term using the information on the operation result of the device as the evaluation factor. Since parameters can be set in the apparatus, parameters can be optimized with high accuracy in a short time.
[0020]
In this case, as in the parameter adjustment method according to claim 2, the first step and the second step are repeatedly performed at least twice before the third step, and in the second and subsequent first steps, The optimal value of each of the specific parameters included in the combination of the optimal values obtained in the second step up to the previous time is set as a predetermined set value in the parameter, and in the second and subsequent second steps, The value of the evaluation function corresponding to the combination of the optimum values obtained in the second step is smaller than the value of the evaluation function corresponding to the combination of the optimum values obtained in the second step. In this case, the combination of the optimum values obtained in the second step may be updated as the combination of the optimum values of the specific parameters.
[0021]
According to this, by repeatedly executing the first step and the second step, the optimum value of the parameter can be sequentially approached to the true optimum solution in the second step, so that the parameter can be optimized with higher accuracy. You can plan.
[0022]
In the parameter adjusting method according to the first or second aspect, as in the parameter adjusting method according to the third aspect, in the second step, each of the specific parameters is determined by using at least one of a least square method and an attenuated least square method. Can be determined.
[0023]
In this case, as in the parameter adjustment method according to claim 4, when the attenuation least squares method is used, the evaluation function is based on a change amount of a set value of each of the specific parameters and a predetermined damping factor. It can further have a term obtained based on it.
[0024]
According to this, when the damped least squares method is applied, the evaluation function includes, in addition to the term using the information on the operation result as the evaluation factor, the amount of change in the set value of each specific parameter and the predetermined damping factor. Is added. Since the damping term serves to prevent the solution from deviating so much that the linear approximation does not hold any more, the present invention enables the optimum solution of each specific parameter to be obtained with high accuracy.
[0025]
In the parameter adjusting method according to any one of claims 1 to 4, as in the parameter adjusting method according to claim 5, in the first step, an operation result when the device is operated a plurality of times is obtained. At least one of the reproducibility and the range may be information on the operation result.
[0026]
In the parameter adjustment method according to any one of claims 1 to 5, as in the parameter adjustment method according to claim 6, prior to the third step, the number of operations of the apparatus in the first step is reduced. As the first predetermined number of times, the first step and the second step are executed, a combination of optimal values of the set values of the specific parameters is obtained, and the specific parameters included in the obtained combination of the optimal values are obtained. Performing the first step and the second step by setting the optimum value of the predetermined parameter as a predetermined set value of each of the specific parameters, and setting the number of times of operation of the apparatus to a second predetermined number of times greater than the first predetermined number of times. It can be.
[0027]
According to this, first, the number of operations of the apparatus is reduced (first predetermined number), the optimum value of the specific parameter is roughly detected, and the approximate approach to the true optimal solution is roughly performed. By increasing the number of times (second predetermined number of times), a true optimum solution is obtained with high accuracy. Therefore, it is possible to reduce the overall number of operations of the apparatus until finding the optimal solution of the specific parameter, rather than increasing the number of operations from the beginning and detecting information on the operation result in close examination, so that parameter adjustment is The time required can be reduced.
[0028]
In the parameter adjustment method according to any one of claims 1 to 6, as in the parameter adjustment method according to claim 7, the first step includes: The set of each specific parameter may be selected, and the first step, the second step, and the third step may be repeatedly executed until the optimal values of all parameters are set.
[0029]
According to this, among the plurality of parameters, the parameters are adjusted in a state in which the number of parameters is appropriately limited in the descending order of the influence on the operation result of the apparatus, so that a large number of parameters are adjusted at once. Since the fluctuation of the evaluation function is not complicated and the adjustment time is not prolonged unnecessarily, each parameter can be adjusted without difficulty.
[0030]
In the parameter adjusting method according to any one of claims 1 to 7, as in the parameter adjusting method according to claim 8, the plurality of parameters are determined by at least one transport system provided in the apparatus. At least one of a transfer speed of the object and a position related to delivery of the object by the transfer system is included, and the information on the operation result includes positioning accuracy of the object after transfer by the transfer system and the position of the object by the transfer system. At least one of the object transport times may be included.
[0031]
That is, these parameter adjustment methods can also be applied to an apparatus for transporting an object. In this case, the parameter to be adjusted is a parameter that can adjust the transfer speed of the object, the position related to the transfer of the object, and the like, and the information about the operation result is the positioning accuracy and the transfer time of the transferred object. In this way, it is possible to obtain the set values of the parameters (for example, the transfer speed and the transfer position) that minimize the evaluation function using the positioning accuracy of the object and the transfer time as the evaluation factors.
[0032]
In the parameter adjustment method according to any one of claims 1 to 7, as in the parameter adjustment method according to claim 9, the plurality of parameters include the device for detecting position information of the object. A parameter that defines a detection operation of the detection system provided in the information processing apparatus, and the information on the operation result includes positioning accuracy of the object positioned based on the position information. Can be.
[0033]
That is, these parameter adjustment methods can be applied to an apparatus for positioning an object. In this case, the parameter that defines the detection operation of the detection system provided in the device for detecting the position information of the object is an adjustable parameter, and the information on the operation result includes the positioning accuracy of the object. become.
[0034]
In the parameter adjustment method according to any one of claims 1 to 9, as in the parameter adjustment method according to claim 10, in the first step, information on an operation result of a simulation of a mathematical model of the device is obtained. The estimated value may be information on the operation result. According to this, parameters can be optimized in a short time by simulation without actually operating the apparatus.
[0035]
The invention according to claim 11, which is a parameter adjustment method for adjusting a set value of a specific parameter that defines an operation of the device, wherein the device when the set value of the specific parameter is sequentially set to a plurality of values A first step of obtaining information on the operation result of the above; and using the information on the obtained operation result as an evaluation factor, and using at least one of a least squares method and an attenuated least squares method to determine an optimum value of the set value of the specific parameter. A parameter adjusting method including: a second step of obtaining; and a third step of setting the optimum value as a set value of the specific parameter in the apparatus.
[0036]
The invention according to claim 12 is an object transporting method for transporting an object (W, W ′), wherein a plurality of parameters (P ₁ An adjustment step of executing the parameter adjustment method according to any one of claims 1 to 11, wherein information on a result of transporting the object is set as information on the operation result. A conveying step of conveying the object based on the adjusted parameters. According to this, the parameter adjustment method according to any one of claims 1 to 11 can be executed to optimize a plurality of parameters defining the object transfer operation, and thus can be performed accurately in a short time. Objects can be transported.
[0037]
The invention according to claim 13 is an object transport method for transporting an object (W, W ′), wherein a plurality of parameters (P, P) defining a transport operation of the object by a transport system (36 or the like) are provided. ₁ Etc.), a transporting step of transporting a plurality of said objects one by one by said transporting system according to a set value; and a detecting step of detecting information on a result of transporting an object each time a predetermined number of objects are transported by said transporting system. Calculating a combination of the optimum values of the set values of the plurality of parameters according to a value of an evaluation function (Φ) having a term in which information on the detected transport result is used as an evaluation factor; And adjusting the plurality of parameters using the optimum values included in the parameters as the respective set values of the plurality of parameters.
[0038]
According to this, every time a predetermined number of objects are transported by the transport system, information on the transport result of the objects is detected, the value of the evaluation function at that time is calculated, and the parameter setting value is set to the value of the evaluation function. It is adjusted to an optimum value based on the value. That is, in the present invention, even if the optimum value of the parameter changes due to, for example, a change over time of the apparatus, the set value of the parameter can be constantly adjusted to the optimum value.
[0039]
In this case, as in the object transporting method according to claim 14, prior to the transporting step, a plurality of combinations of the set values of the respective parameters based on predetermined set values of the plurality of parameters are used. Calculating the value of an evaluation function having a term with the information on the transport result as an evaluation factor for each combination when sequentially setting and trying to transport the object by the transport system. And a table creation step of creating a table showing a correlation between the variation of the plurality of parameters and the variation of the evaluation function, wherein the adjustment step is performed based on information on the transport result detected in the detection step. When the value of the evaluated evaluation function is increased, the table is referred to, and the value of the evaluation function is reduced. It can be achieved by selecting the combination of set values of parameters.
[0040]
According to this, before actually executing the transfer of the object, a table indicating the correlation between the change in the set value of each parameter and the change in the information on the transfer result is created in advance, and during the exposure process, When the evaluation function calculated based on the information on the transport result detected in the detection process becomes large, the setting value of each parameter such that the value of the evaluation function can be reduced by referring to the table Can be obtained in a short time, so that the time required for parameter optimization during operation of the apparatus can be reduced.
[0041]
The invention according to claim 15 is an exposure apparatus (100) for exposing an object (W, W ′), wherein at least one parameter (for example, P ₁ And (30 etc.); a stage (WST) for holding the object conveyed by the conveyance system; and a stage (WST) for conveying the object by the conveyance system and held by the stage. A detection system (ALG) for detecting information on a result of transporting an object; and a setting value of the at least one parameter based on a value of an evaluation function having a term using the detected information on the operation result as an evaluation factor. An adjustment device (20) for obtaining an optimum value and adjusting a set value of the at least one parameter based on the optimum value.
[0042]
According to this, the object conveyed by the conveyance system and held on the stage is exposed based on the set value of at least one parameter optimally adjusted by the adjustment device. An improvement can be realized.
[0043]
The invention according to claim 16 is a program for causing a computer to execute a procedure for adjusting the set values of a plurality of parameters defining the operation of the apparatus, wherein each of the at least two specific parameters selected from the plurality of parameters is specified. Based on a predetermined set value of, a plurality of combinations of the set values of the specific parameters, information on the operation results of the device when sequentially set in the device, information on the obtained operation results A first procedure for calculating a value of an evaluation function having a term as an evaluation factor for each of the combinations; a combination of optimal values of the set values of the specific parameters based on the value of the evaluation function calculated for each of the combinations; And setting the optimum value included in the combination of the optimum values as the set value of each of the specific parameters in the device. That third procedure; is a program for causing the computer to execute.
[0044]
By executing this program on a computer, the parameter adjustment method of the present invention is realized, and parameter optimization can be performed with high accuracy in a short time.
[0045]
In this case, as in the program according to claim 17, the computer causes the computer to repeatedly execute the first procedure and the second procedure at least twice prior to the third procedure, and the second procedure and subsequent steps are performed. Then, the optimal value of each specific parameter included in the combination of the optimal values obtained in the second procedure up to the previous time is set as a predetermined setting value of the parameter, and in the second and subsequent second procedures, Than the value of the evaluation function corresponding to the combination of the optimal values obtained in the second procedure up to the value of the evaluation function corresponding to the combination of the optimal values obtained in the second procedure this time If it is smaller, a procedure for updating the combination of the optimum values obtained in the second procedure at this time as a combination of the optimum values of the specific parameters may be executed.
[0046]
In the program according to claim 16 or 17, as in the program according to claim 18, in the second step, the optimal value of each of the specific parameters is determined by using at least one of a least square method and an attenuated least square method. The computer may execute the procedure for obtaining the combination.
[0047]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
[0048]
FIG. 1 shows an exposure apparatus 100 according to an embodiment suitable for carrying out a parameter adjustment method and an object transport method according to the present invention. The exposure apparatus 100 is a step-and-scan type projection exposure apparatus.
[0049]
The exposure apparatus 100 includes an illumination system 12 including an exposure light source, a reticle stage RST holding a reticle R as a mask, a projection optical system PL, a wafer stage WST as a stage on which a wafer W as an object is mounted, and It has a control system and the like.
[0050]
The illumination system 12 includes a light source and an illuminance uniforming optical system including an optical integrator (such as a fly-eye lens, an internal reflection type integrator, or a diffractive optical element) as disclosed in, for example, Japanese Patent Application Laid-Open No. 6-349701. The illumination optical system includes a system, a relay lens, a variable ND filter, a reticle blind, and a dichroic mirror (all not shown). In the illumination system 12, a slit-shaped illumination area IAR defined by a reticle blind on a reticle R on which a circuit pattern or the like is drawn is illuminated with illumination light IL with substantially uniform illuminance. Here, as the illumination light IL, far ultraviolet light such as KrF excimer laser light (wavelength 248 nm), ArF excimer laser light (wavelength 193 nm), or F ₂ Vacuum ultraviolet light such as laser light (wavelength 157 nm) is used. As the illumination light IL, an ultraviolet bright line (g-line, i-line, or the like) from an ultra-high pressure mercury lamp can be used.
[0051]
Here, each drive unit in the illumination system 12, that is, a variable ND filter, a reticle blind, and the like are controlled by an illumination control device (exposure controller) 14 in accordance with an instruction from the main control device 20.
[0052]
The reticle stage RST is arranged on a reticle base plate 13, and a reticle R is fixed on the upper surface thereof, for example, by vacuum suction. The reticle stage RST is, for example, in a plane perpendicular to an optical axis of an illumination optical system (coincident with an optical axis AX of a projection optical system PL described later) by a reticle stage driving unit (not shown) including a linear motor, a voice coil motor, and the like. (In the XY plane), two-dimensionally (in the X-axis direction, in the Y-axis direction perpendicular to the X-axis direction, and in the rotation direction (θz direction) around the Z-axis perpendicular to the XY plane), and at a predetermined scanning speed. It is possible to drive at a scanning speed designated in the direction (here, the Y-axis direction). The reticle stage RST has a movement stroke in the Y-axis direction that allows the entire surface of the reticle R to cross at least the optical axis of the illumination system 12.
[0053]
The side surface of reticle stage RST is mirror-finished, and has a reflecting surface that reflects an interferometer beam from reticle laser interferometer (hereinafter referred to as “reticle interferometer”) 16. In the reticle interferometer 16, the return light from the reflection surface and the return light from a reference unit (not shown) interfere with each other, and based on the photoelectric conversion signal of the interference light, the reticle stage RST in the stage moving plane (XY plane) of the reticle stage RST. The position (including the θz rotation) is always detected with a resolution of, for example, about 0.5 to 1 nm. Actually, the reticle interferometer 16 has at least two measurement axes in the scanning direction and at least one measurement axis in the non-scanning direction.
[0054]
The position information of the reticle stage RST from the reticle interferometer 16 is sent to the stage control device 19 and the main control device 20 via the stage control device 19. The reticle stage RST is driven via a reticle stage driving unit (not shown) based on the information.
[0055]
The projection optical system PL is disposed below the reticle stage RST in FIG. 1, and the direction of the optical axis AX (coincident with the optical axis of the illumination optical system) is the Z-axis direction. As the projection optical system PL, for example, a refraction optical system which is telecentric on both sides and includes a plurality of lens elements arranged at predetermined intervals along the optical axis AX direction is used. The projection magnification of the projection optical system PL is, for example, 1/5 (or 1/4).
[0056]
Therefore, when the illumination region IAR of the reticle R is illuminated by the illumination light IL from the illumination system 12, the illumination light IL that has passed through the reticle R causes the reticle R in the illumination region IAR to pass through the projection optical system PL. A reduced image (partially inverted image) of the circuit pattern is formed on a wafer W having a surface coated with a resist (photosensitive agent).
[0057]
The wafer stage WST is arranged on a wafer base board 17 arranged below the projection optical system PL in FIG. 1, and a wafer holder 18 is mounted on the wafer stage WST. A wafer W having a diameter of, for example, 12 inches (about 300 mm) is held on the wafer holder 18 by vacuum suction. The wafer holder 18 can be tilted in any direction with respect to the best image forming plane of the projection optical system PL by a driving unit (not shown), and can be finely moved in the optical axis AX direction (Z-axis direction) of the projection optical system PL. Have been. Further, the wafer holder 18 is also capable of rotating around the Z axis.
[0058]
Wafer stage WST is moved not only in the scanning direction (Y-axis direction) but also in the scanning direction so that a plurality of shot areas on wafer W can be moved relative to exposure area IA to perform scanning exposure. It is also configured to be movable in the orthogonal non-scanning direction (X-axis direction), and performs an operation of scanning (scanning) exposing each shot area on the wafer W and moving to an acceleration start position for exposure of the next shot. And a step-and-scan operation that repeats the above operation. Details of this step-and-scan operation will be described later.
[0059]
Wafer stage WST is driven by wafer driving device 15 in two-dimensional directions of the X axis and the Y axis. Wafer driving device 15 drives wafer stage WST in the Y-axis direction integrally with an X-axis linear motor that drives wafer stage WST in the X-axis direction and an X-axis linear guide that is a stator of the X-axis linear motor. Although it is configured to include a total of three linear motors including a pair of Y-axis linear motors, they are shown in blocks for convenience of illustration in FIG.
[0060]
The position of wafer stage WST is measured by wafer laser interferometer 24. In other words, the side surface on one side (−X side) in the X-axis direction and the side surface on one side (+ Y side) in the Y-axis direction of wafer stage WST are mirror-finished to form reflection surfaces. The interferometer beams are radiated from the wafer laser interferometer 24 to these reflecting surfaces, respectively, and the return light from the respective reflecting surfaces and the return light from a reference unit (not shown) interfere with each other, based on a photoelectric conversion signal of the interference light. The position of the wafer stage WST is constantly detected by the wafer laser interferometer 24 with a resolution of, for example, about 0.5 to 1 nm. Note that wafer laser interferometer 24 is actually an X-axis interferometer that irradiates an interferometer beam to one side (−X side) in the X-axis direction of wafer stage WST, and one side in the Y-axis direction (+ Y side). And a Y-axis interferometer for irradiating an interferometer beam to the side surface of the light source. These X-axis interferometer and Y-axis interferometer are multi-axis interferometers each having a plurality of length measurement axes. In addition to the X position and Y position of wafer stage WST, rotation (θz rotation (yawing), X axis Measurement of θx rotation (pitching), which is rotation around, and θy rotation (rolling), which is rotation around Y axis, is also possible. The plurality of length measurement axes in the X-axis direction include a length measurement axis passing through the optical axis AX of the projection optical system PL and a length measurement axis passing through the detection center of the alignment system ALG described later. At least one of the plurality of axial measurement axes passes through the optical axis AX of the projection optical system PL and the detection center of the alignment system ALG. Thus, in the wafer laser interferometer 24 of the present embodiment, the X and Y positions of the wafer stage WST can be measured without any so-called Abbe error both during exposure and during alignment.
[0061]
The measured values of the wafer laser interferometer 24 on each measurement axis are sent to the stage controller 19 of FIG. 1 and the main controller 20 via the same, and the stage controller 19 responds to an instruction from the main controller 20. The position of wafer stage WST is controlled accordingly. As described above, a plurality of interferometers are provided as interferometers for measuring the position of wafer stage WST, but these are representatively shown as wafer laser interferometer 24 in FIG.
[0062]
As shown in FIG. 1, a reference mark plate FM is fixed on wafer stage WST so that its surface is substantially at the same height as the surface of wafer W. On the surface of the fiducial mark plate FM, for example, a fiducial mark for baseline measurement and other fiducial marks for measuring a relative positional relationship between a position of a detection center of an alignment system ALG described later and a position of a projected image of the reticle pattern are described. Is formed.
[0063]
Further, in the exposure apparatus 100 of the present embodiment, as shown in FIG. 1, each shot on the wafer W is provided on the side surface of the projection optical system PL, more specifically, on the −Y side surface of the projection optical system PL. An off-axis type alignment system ALG for detecting the position of an alignment mark (wafer mark) attached to the region is provided. As the alignment system ALG, for example, as disclosed in JP-A-2-54103. An FIA (Field Image Alignment) -based alignment sensor is used. The alignment system ALG irradiates the wafer with illumination light (for example, white light) having a predetermined wavelength width, and forms an image of an alignment mark on the wafer and an index mark on an index plate disposed in a plane conjugate with the wafer. Is formed on the light receiving surface of an image sensor (CCD camera or the like) by an objective lens or the like and detected. The alignment system ALG outputs an imaging result of the alignment mark (or the reference mark on the reference mark plate FM) to the main controller 20.
[0064]
Further, in the exposure apparatus 100, an image forming light beam (detection beam FB) for forming a plurality of slit images toward the best image forming plane of the projection optical system PL is supplied obliquely with respect to the optical axis AX direction. Irradiation optical system AF ₁ And a light-receiving optical system AF for receiving the respective reflected light beams of the image-formed light beam on the surface of the wafer W through slits. ₂ Is fixed to a holding member (not shown) that supports the projection optical system PL. This multipoint focus position detection system AF (AF ₁ , AF ₂ ), A configuration similar to that disclosed in, for example, Japanese Patent Application Laid-Open No. 6-283403 is used, and a positional deviation of a plurality of points on the wafer surface with respect to the imaging plane in the Z direction is detected. It is used to drive the wafer holder 18 in the Z-axis direction and the tilt direction so as to keep a predetermined distance from the projection optical system PL. The wafer position information from the multipoint focus position detection system AF is sent to the stage controller 19 via the main controller 20. The stage controller 19 drives the wafer holder 18 in the Z direction and the tilt direction based on the wafer position information.
[0065]
A center table 30 is formed near the center of the wafer holder 18 placed on the wafer stage WST, as can be understood from FIGS. 2A to 2C. The center table 30 is connected to, for example, a link mechanism (not shown). When the link mechanism is driven, for example, by rotation of a cam (not shown), the center table 30 moves up and down by driving the link mechanism, and On the contrary, it is possible to appear. The rotation control of the cam is performed by the main controller 20 via the stage controller 19. The center table 30 is provided for transferring wafers. When a wafer is transferred between the wafer holder 18 and another, the center table 30 is raised while supporting the wafer, and the wafer is floated from the wafer holder 18. The wafer is transferred when the center table 30 is at a position slightly deviated from the top dead center of the cam-link mechanism in the Z-axis direction and the center table 30 is at the most stable position. Done in This stable position (this is referred to as a “wafer transfer position”) can be measured by a predetermined measuring device, and is measured by the measuring device when the device is started up or at the time of maintenance. The position is set in the device.
[0066]
An opening 30a is provided substantially at the center of the portion of the center table 30 that contacts the wafer, and the opening 30a communicates with a supply / exhaust mechanism (not shown). Although not shown, a peripheral wall is provided over the center table 30 over the outer periphery thereof. When the air is exhausted by the air supply / exhaust mechanism with the wafer placed on the center table 30, the pressure in the area surrounded by the wafer, the upper part of the center table 30 and the peripheral wall is reduced, and the wafer is pushed to the atmospheric pressure. As a result, the center table 30 is vacuum-sucked. That is, if the exhaust is performed by the supply / exhaust mechanism while supporting the wafer, the center table 30 can hold the wafer by vacuum suction.
[0067]
Although not shown, a large number of pins are arranged at predetermined intervals on a support surface of the center table 30 that supports the wafer, and the wafer is supported by the tips of the large number of pins. It will be. Therefore, even if air is exhausted by the above-described air supply / exhaust mechanism and the wafer is pressed toward the center table 30 by the external air pressure, the wafer is supported by a uniform force and does not deform. Note that a large number of such pins are also arranged on the wafer holder 18, and the wafer is supported by these pins when placed on the wafer holder 18.
[0068]
Returning to FIG. 1, the exposure apparatus 100 further includes a wafer pre-alignment apparatus 32 arranged at a wafer exchange position. The wafer pre-alignment apparatus 32 is provided below the pre-alignment apparatus main body 34 and the pre-alignment apparatus main body 34, and suspends and supports a wafer carry-in arm (hereinafter, referred to as a "carry-in arm") 36 to vertically move and rotate. It includes a drivable vertical movement / rotation mechanism 38 and three measurement units 40a, 40b, 40c arranged above the carry-in arm 36. The wafer pre-alignment apparatus 32 further includes, as shown in FIG. 3, prisms 41a, 41b, and 41c as three reflecting members provided for the three measurement units 40a, 40b, and 40c, respectively. There are provided three prism driving mechanisms 43a, 43b and 43c for individually driving these prisms 41a to 41c.
[0069]
Each of the prism driving mechanisms 43a to 43c has a motor, and is suspended and supported by a part of a body (not shown) of the exposure apparatus 100 via support members 45a, 45b, and 45c. Each of the prisms 41a to 41c is attached to a drive shaft (rotation axis) of a prism drive mechanism 43a to 43c via an L-shaped support member 47a to 47c, respectively. In this case, the prism driving mechanisms 43a to 43c irradiate each of the prisms 41a to 41c with a first position (see FIG. 3) where detection light is emitted from the measurement units 40a, 40b, and 40c as described below. ) And a second position (see FIG. 4) where the detection light from the measurement units 40a, 40b, and 40c is not irradiated. The prism driving mechanisms 43a to 43c are controlled by the stage control device 19 based on instructions from the main control device 20.
[0070]
The measurement unit 40b includes a housing 53 and a light source 55, a lens 57, a bending mirror 59, a lens 61, and a light source 55 arranged in a predetermined positional relationship in the housing 53, as shown in FIG. A CCD camera 63 and the like are provided. Here, the lens 57 is actually held by a lens holder (not shown), and has a structure in which the tilt angle of the lens holder can be adjusted. That is, the structure is such that the direction of the optical axis of the lens 57 can be adjusted to a desired angle via the lens holder. Circular openings 53a and 53b are formed in the housing 53 below the lens 57 and the folding mirror 59, respectively.
[0071]
Here, the principle of measuring the outer shape of the 12-inch wafer (hereinafter, referred to as “wafer W ′”) held by the loading arm 36 by the measurement unit 40b will be briefly described with reference to FIG. In a state where the prism 41b is at the first position (see FIG. 3) below the wafer W ′, that is, in a state as shown in FIG. 5, the detection light DL from the light source 55 is transmitted through the lens 57 to the prism 41b. Is illuminated by epi-illumination. That is, in the present embodiment, the light source 55 and the lens 57 constitute an epi-illumination system. Then, this light DL is sequentially reflected by the reflection surface of the prism 41b, and is reflected a plurality of times as shown in FIG. 5, and then, from below vertically, at a predetermined position on the outer edge of the wafer W ′, specifically, a notch (V-shaped) (Notch-shaped portion). That is, the vicinity of the notch of the wafer W ′ is illuminated from below by the light DL. Then, the optical path of the light DL is bent by 90 ° by the bending mirror 59 and is incident on the light receiving surface (imaging surface) of the CCD camera 63 via the lens 61. That is, thereby, an image near the notch portion of the wafer W ′ is formed on the light receiving surface of the CCD camera 63, and the image is captured by the CCD camera 63. Then, an imaging signal of the image near the notch portion is sent to a signal processing system (image processing system) (not shown) inside the main body 34 of the pre-alignment apparatus.
[0072]
The other measurement units 40a and 40c are also configured in the same manner as the measurement unit 40b, and similarly in the vicinity of a predetermined portion of the outer edge of the wafer W ′ via the prisms 41a and 41c, specifically, the peripheral portion other than the notch portion. An image in the vicinity is captured, and an imaging signal including the imaging result is sent to a signal processing system.
[0073]
Inside the pre-alignment apparatus main body 34, a control device including the signal processing system, the control system of the vertical movement / rotation mechanism 38, and the like is built.
[0074]
The wafer pre-alignment device 32 is controlled by the stage control device 19 based on an instruction from the main control device 20 in FIG. 1, and detects the outer edge (outer shape) of the wafer W ′ by the three measurement units 40a, 40b, and 40c. Then, the imaging signals from the three measurement units 40a, 40b, and 40c are processed by a control device built in the pre-alignment device main body 34. Based on the signals from the control device, the stage controller 19 controls the X, Y and θz errors are determined. The stage control device 19 controls the vertical movement / rotation mechanism 38 to correct the θz error.
[0075]
Also, as shown in FIG. 6A, the position of the notch on the wafer W ′ is the position of the measurement unit 40b, and therefore the direction is the −Y direction (direction at 6:00) when viewed from the center of the wafer W ′. The wafer W ′ may be placed on the wafer holder 18 in a state rotated by 90 ° from this state, that is, in a state where the notch comes in the + X direction (3 o'clock direction) when viewed from the center of the wafer W. In such a case, as described in, for example, Japanese Patent Application Laid-Open No. 9-36202, a measuring unit (with a built-in CCD camera) is arranged at a position corresponding to both the 3 o'clock direction and the 6 o'clock direction. (5 measurement units for imaging the areas VA to VE, respectively), or 90 ° using the vertical movement / rotation mechanism 38 of the wafer pre-alignment apparatus 32 after detecting the outer shape using the measurement units 40a, 40b, and 40c. You may make it rotate.
[0076]
As shown in FIG. 6B, a wafer provided with an orientation flat (hereinafter abbreviated as “OF”) also has a −Y direction (6 o'clock direction) or a + X direction (3 o'clock direction). In some cases, the wafer W 'is placed on the wafer holder 18 with the OF coming in the direction of (3), so that the measurement unit (built-in CCD camera) is located at a position corresponding to both the 3 o'clock direction and the 6 o'clock direction. ) May be arranged (six measurement units for imaging the areas VA to VF, respectively). The method of this embedding, the optical arrangement, and the method of calculating the XYθ error of the wafer are known, and are substantially the same as, for example, the method described in JP-A-9-36202. I do.
[0077]
The X and Y errors obtained based on the outer shape measurement of the wafer W ′ by the wafer pre-alignment device 32 are sent to the main controller 20 via the stage controller 19. Then, based on an instruction from main controller 20, stage controller 19 minutely drives wafer stage WST by the X and Y error, for example, when carrying wafer W '(described later) into wafer holder 18 (at the time of loading). It is corrected by this. Alternatively, correction can be made by adding an offset corresponding to the X and Y errors at the time of wafer alignment.
[0078]
FIG. 7 shows the carry-in arm 36 taken out. As shown in FIG. 7, the carry-in arm 36 includes a horizontal member 42 horizontally attached to a lower end of a drive shaft 46 driven by a vertical movement / rotation mechanism 38, and a longitudinal direction (X-axis) of the horizontal member 42. (Extended direction), which is fixed to one side (+ X side) and extends a predetermined length in a direction (Y-axis direction) perpendicular to the longitudinal direction, and a pair of projections projecting downward from both ends of the extended portion 44. L-shaped hook portions 50a and 50b, and a hook portion 50c protruding downward from the other end of the horizontal member 42 in the longitudinal direction. Each of the hook portions 50a and 50b has a shape in which its lower end is protruded inward (−X side) by a length a. The remaining hook portion 50c also has a shape protruding inward (+ X side) by a length a.
[0079]
The upper surfaces of the lower ends of these hook portions 50a to 50c are located on substantially the same XY plane, and are provided with suction holes (not shown) for sucking the back surface of the wafer. The distance d between the tips of the hooks 50c is smaller than 12 inches (diameter of the wafer), and the length obtained by adding the length 2a to the distance d is set to be longer than 12 inches. I have. Further, the interval d is set so as to be wider than the width in the X-axis direction of a portion indicating a wafer in the wafer transfer arm 54 described later and the diameter of the center table 30. Further, a space wider than the diameter of the wafer is provided above a portion of the hook portions 50a to 50c where the suction holes are provided. Therefore, a wafer can be carried into this space from the -Y direction by a wafer carrying arm 54 described later, and the carrying arm 36 sucks the back surface of the wafer through the suction holes of the hook portions 50a, 50b, and 50c. The wafer can be transferred up and down while being held.
[0080]
As shown in FIG. 4, the carry-out arm 52 and the wafer transfer arm 54 are driven by an arm drive mechanism 56 at a predetermined stroke along the Y-axis direction. The arm driving mechanism 56 includes a linear guide 60 extending in the Y-axis direction, and vertical movement / slide mechanisms 58 and 62 that reciprocate in the Y-axis direction along the linear guide 60. Of these, the above-mentioned carry-out arm 52 is held by a vertical movement / slide mechanism 58, and the carry-out arm 52 is driven vertically in a predetermined range by the vertical movement / slide mechanism 58. The wafer transfer arm 54 is held by a vertical movement / sliding mechanism 62 so that it can be driven up and down within a predetermined range. The arm drive mechanism 56 including the vertical movement / slide mechanisms 58 and 62 is controlled by the stage control device 19 in FIG. In this case, it is desirable that the linear guide 60 be mounted on a stand separate from the body of the exposure apparatus 100 including the wafer base board 17 and the like in order to prevent vibration.
[0081]
The control system is mainly composed of a main controller 20 and a stage controller 19 under the main controller 20 in FIG. The main controller 20 includes a so-called microcomputer (or workstation) including a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory), and the like. And control.
[0082]
The main controller 20 includes, for example, an input device such as a keyboard (not shown), a display device (not shown) such as a CRT display (or a liquid crystal display), a CD (Compact Disc), a DVD (Digital Versatile Disc), A drive device (not shown) of an information recording medium such as an MO (Magneto-Optical Disc) or an FD (Flexible Disc) is connected. The information recording medium (hereinafter, referred to as a CD) set in the drive device stores a program or the like corresponding to a processing algorithm such as an overall operation and a parameter adjustment operation in the exposure apparatus 100 shown in a flowchart described later. Has been recorded. Further, a storage device 21 for storing device parameters and the like is connected to the main control device 20 as described later.
[0083]
It is assumed that programs and the like in a CD-ROM set in the drive device are installed in the storage device 21. Further, it is assumed that a program of the parameter adjustment operation is loaded from the storage device 21 to the main memory by the CPU inside the main control device 20.
[0084]
Next, the overall operation of the exposure apparatus 100 configured as described above will be described focusing on the operation of the wafer transfer system with reference to FIGS.
[0085]
In the exposure apparatus 100, the operations of the illumination system 12, the reticle stage RST, the wafer stage WST, and other components are managed by the main controller 20 via the illumination controller 14, the stage controller 19, and the like. The reticle pattern is sequentially transferred to each shot area on wafer W held by wafer holder 18 on wafer stage WST by exposure in the step-and-scan method in the same procedure as described above.
[0086]
When the step-and-scan exposure is performed on the wafer W, the main controller 20 instructs the stage controller 19 to transfer the next wafer W ′ to be exposed to the wafer exchange position. I do. As a result, the following operation is performed until the exposure is completed.
[0087]
That is, as shown in FIG. 4, the wafer transfer arm 54 holding the wafer W ′ in which the position in the X-axis direction and the Y-axis direction and the direction of the notch are roughly adjusted is moved by the arm drive mechanism 56 by the stage controller 19 as shown in FIG. Is driven to a predetermined position (a position where the wafer can be transferred) in the space of the carry-in arm 36 waiting above the wafer exchange position (see the arrow YA in FIG. 4). In this case, the wafer W ′ held by the wafer transfer arm 54 is loaded into the space of the loading arm 36 described above. At this time, the unloading arm 52 is still in a standby state on the −Y side (see FIG. 8A). It is assumed that the position of the carry-in arm 36 in the Z-axis direction is detected by a sensor (not shown), and that position information is sent to the stage control device 19.
[0088]
In this state, the stage controller 19 raises the carry-in arm 36 by a predetermined amount, and when the carry-in arm 36 reaches a predetermined position, releases the suction of the wafer W ′ by the wafer transfer arm 54 at an appropriate timing. The vacuum suction of the wafer W 'by the loading arm 36 is started at an appropriate timing (the vacuum is turned on).
[0089]
When the carry-in arm 36 rises until the wafer W 'is completely supported by the carry-in arm 36 (see FIG. 8B), the stage controller 19 retreats the wafer transfer arm 54 to the -Y side (see FIG. 8B). FIG. 8C). Thus, the transfer of the wafer W ′ to the carry-in arm 36 is completed (see FIG. 8D).
[0090]
The main controller 20 confirms the completion of the transfer of the wafer W ′ based on, for example, an output of a sensor (not shown) that detects a change in pressure in a vacuum suction path connected to the carry-in arm 36. Instruct 19 to move the prisms 41a to 41c from the second position (the state shown in FIG. 4) to the first position (the state shown in FIG. 3). Based on this instruction, the stage control device 19 moves the prisms 41a to 41c to a first position (see FIG. 3) below the wafer W ′ held by the carry-in arm 36.
[0091]
Main controller 20 confirms that the movement (insertion) of prisms 41 a to 41 c to the first position below the wafer has been completed based on the output of a sensor (not shown), and sends a wafer W to stage controller 19. 'Pre-alignment measurement. Based on this instruction, the stage control device 19 starts the above-described outer shape measurement of the wafer W ′ using the measurement units 40a to 40c included in the pre-alignment device 32. That is, the pre-alignment of the wafer W ′ using the wafer pre-alignment device 32 is started in this way.
[0092]
In this pre-alignment, three regions (VA, VB, VC) near the outer edge of wafer W ′ shown in FIG. 6A are imaged by measurement units 40a to 40c, respectively. The imaging result is sent to the pre-alignment apparatus main body 34, and the pre-alignment apparatus main body 34 uses a statistical method based on the imaging data, specifically, based on a difference in brightness between the wafer W ′ and the background. At least three points (one of them is the position of the notch) are detected as the positions of the outer edge of the wafer W ′ including the position of the notch by image processing using the method described above. The center position and the position of the notch are calculated and sent to the stage controller 19.
[0093]
The stage controller 19 calculates the information of the X, Y, θz errors of the wafer W ′ obtained by the measurement based on the received information on the center position, the notch position, and the radius of the wafer W ′, In addition to notifying the main controller 20, the carry-in arm 36 is rotated via the vertical movement / rotation mechanism 38 to correct the θz rotation error. In parallel with the correction of the rotation error of the wafer W ′, the stage controller 19 retracts the prisms 41 a to 41 c to the second position shown in FIG. 4 based on an instruction from the main controller 20.
[0094]
Thereafter, the carry-in arm 36 stands by while supporting the wafer W ′ until the exposure of the wafer W is completed.
[0095]
On the other hand, when exposure of wafer W is completed, main controller 20 instructs stage controller 19 to move wafer stage WST to the wafer exchange position. Thereby, stage control device 19 moves wafer stage WST to the wafer exchange position via wafer driving device 15 while monitoring the measurement value of wafer laser interferometer 24. By the above operation, as shown in FIG. 9A, the carry-in arm 36 and the wafer stage WST are vertically overlapped at the wafer exchange position and above the wafer exchange position. At this time, the stage control device 19 moves the wafer W 'to a position where the errors are canceled based on the information of the errors of X and Y among the information of the errors of X, Y and θz of the wafer W ′. It is assumed that wafer stage WST is positioned.
[0096]
When wafer stage WST reaches the wafer exchange position, main controller 20 instructs stage controller 19 to unload wafer W. Accordingly, the stage control device 19 releases the vacuum suction of the wafer W by the wafer holder 18, then starts the vacuum suction of the wafer W by the center table 30 at an appropriate timing, and further raises the center table 30 by a predetermined amount. Thereafter, the carry-out arm 52 is moved in the direction of the arrow YB shown in FIG. 4, and the carry-out arm 52 is inserted below the wafer W (see FIG. 9B). The position of the center table 30 in the Z-axis direction is measured by a sensor (not shown), and the position information is transmitted to the stage control device 19.
[0097]
Then, the stage controller 19 lowers the center table 30 and, when the center table 30 reaches a predetermined position, immediately after releasing the suction of the wafer W by the center table 30, the wafer W Start adsorption. As a result, the wafer W is transferred from the center table 30 to the carry-out arm 52. Then, when the wafer W is supported only by the unloading arm 52, the stage control device 19 retracts the unloading arm 52 to the -Y side. Thus, unloading of wafer W from wafer stage WST is completed (see FIG. 9C).
[0098]
Next, the stage controller 19 lowers the carry-in arm 36 from the position shown in FIG. 10A to the position where the wafer W is placed on the center table 30 shown in FIG. At this time, when the carry-in arm 36 reaches the predetermined position, the stage control device 19 releases the vacuum suction of the carry-in arm 36 with respect to the wafer W ′, and immediately thereafter, at an appropriate timing, with respect to the wafer W ′ by the center table 30 at an appropriate timing. Start vacuum suction.
[0099]
The carry-in arm 36 continues to descend until the wafer W 'is supported only by the center table 30, that is, until the hooks 50a, 50b, 50c of the carry-in arm 36 are completely separated from the wafer W'. Thereafter, when the wafer W 'is completely held by the vacuum suction force of the center table 30, the stage control device 19 moves the wafer stage WST in the + Y direction (see FIG. 10C).
[0100]
Further, the stage controller 19 lowers the center table 30 and places the wafer W ′ on the wafer holder 18. At this time, when the center table 30 reaches a predetermined position, the stage controller 19 releases the vacuum suction of the center table 30 and starts the vacuum suction by the wafer holder 18 at an appropriate timing. The wafer W ′ is held. As described above, the X, Y, and θz errors of the wafer W ′ measured by the pre-alignment device 32 are canceled by the rotation of the loading arm 36 and the correction of the position of the wafer stage WST. Is held at a desired position on wafer stage WST (see FIG. 10D). On the other hand, the carry-in arm 36 is raised to the position shown in FIG.
[0101]
As described above, the wafer exchange operation is completed, and an “exposure preparation end command” is sent from the stage control device 19 to the main control device 20. Main controller 20 receives the "exposure preparation end command", and instructs stage controller 19 to move wafer stage WST to the wafer alignment start position when confirming the end of the wafer exchange. Thereafter, the processing shifts to an alignment sequence of the wafer W ′.
[0102]
Stage controller 19 moves wafer stage WST to a wafer alignment start position along a predetermined path via wafer driving device 15 while monitoring the measurement value of wafer laser interferometer 24 based on the above instruction. At this time, wafer stage WST moves in the + Y direction by a predetermined distance from the standby position, that is, in the opposite direction to the same path as when moving to the wafer exchange position.
[0103]
After the movement of wafer stage WST to the above-described wafer alignment start position, wafer alignment is performed. Here, the description will be made on the assumption that the exposure of the first layer of the wafer W ′ has already been completed and the exposure of the second layer and thereafter is performed. In this case, as shown in FIG. 11, the circuit pattern of each shot area or the XY of each shot area SA formed on the street line between the shot areas SA is formed on the wafer W '. It is assumed that search alignment marks SYM and SθM are formed at predetermined positions in a portion other than the shot area, in addition to an X mark and a Y mark (not shown) for detecting position information. The search alignment marks SYM and SθM are formed at positions where the distance in the X-axis direction is long and the distance in the Y-axis direction from the center position of the wafer W ′ is long. Is formed such that if the formation position is obtained, the arrangement coordinate system of the plurality of shot areas SA formed on the wafer W ′ can be roughly detected.
[0104]
Main controller 20 first instructs stage controller 19 to move wafer stage WST so that search alignment mark SYM falls within the imaging field of view of alignment system ALG. Stage control device 19 that has received this instruction moves wafer stage WST via wafer driving device 15. After completion of movement of wafer stage WST, main controller 20 instructs alignment system ALG to perform imaging. According to this instruction, the alignment system ALG takes an image of an area including the search alignment mark SYM. The imaging result is transmitted to main controller 20, and main controller 20 determines the position (X) of search alignment mark SYM on the stage coordinate system based on the imaging result. ₁ , Y ₁ ). It is desirable that the position can be obtained with high accuracy based on image processing using a statistical method, for example, processing such as template matching.
[0105]
Next, main controller 20 first instructs stage controller 19 so that search alignment mark SθM falls within the imaging field of view of alignment system ALG. Upon receiving this instruction, stage control device 19 drives wafer driving device 15 to move wafer stage WST to a position where search alignment mark SθM falls within the imaging field of view of alignment system ALG. Next, main controller 20 instructs alignment system ALG to perform imaging. With this instruction, the alignment system ALG takes an image of an area including the search alignment mark SθM. The imaging result is sent to main controller 20, and main controller 20 determines the position (X) of search alignment mark SθM on the stage coordinate system based on the imaging result. ₂ , Y ₂ ) Is calculated. This position is accurately obtained based on image processing using a statistical method, for example, processing such as template matching.
[0106]
Main controller 20 determines the position of search alignment mark SYM (X ₁ , Y ₁ ) And the position of the search alignment mark SθM (X ₂ , Y ₂ ), The amount of displacement (referred to as (ΔX, ΔY)) and the amount of rotational displacement (referred to as Δθ) of the center position of the wafer W ′ with respect to the stage coordinate system are calculated. For example, the distance between the two marks in the design or the displacement in the Y-axis direction (Y ₁ -Y ₂ ) Is obtained from Δ), and the positional deviation between the center position of the wafer W ′ when the Δθ is canceled and the original central position of the wafer W ′ is the positional deviation amount (ΔX, ΔY).
[0107]
Then, main controller 20 sequentially moves wafer stage WST via stage controller 19, and aligns marks (wafer marks) attached to predetermined specific shot areas (sample shots) on wafer W '. Are sequentially detected using the alignment system ALG, and using the detection result (the relative position between each mark and the detection center of the alignment system ALG) and the measurement value of the wafer laser interferometer 24 when each mark is detected, The position of the wafer mark of the sample shot is determined, and based on the determined position of the wafer mark, the rotation, orthogonality, X, and Y of the entire wafer are calculated by a statistical operation disclosed in, for example, JP-A-61-44429. Calculate linear errors represented by scaling in the direction (magnification error) and offsets in the X and Y directions. EGA (Enhanced Global Alignment) for calculating the array coordinates of the shot area on the wafer W ′ based on the calculation result is performed. Here, the X position and the Y position of wafer stage WST at the time of wafer alignment are based on the measured value on the measurement axis in the Y-axis direction passing through the optical axis AX of projection optical system PL and the detection center of alignment system ALG, and the alignment system. It is managed on the basis of the measurement value on the length measurement axis in the X-axis direction passing through the detection center of ALG.
[0108]
At this time, when the alignment mark is detected, the displacement amount (ΔX, ΔY) and the rotational deviation amount Δθ of the wafer W ′ are taken into account when the wafer stage is moved. There is no deviation from the field of view of the ALG.
[0109]
Here, as described above, the measurement axis of the wafer laser interferometer 24 used for measuring the X position and the Y position of the wafer stage WST has a positional relationship with respect to the alignment system ALG such that an Abbe error does not occur. No error occurs due to yawing (θz rotation) of wafer stage WST. However, since the height of the surface of the wafer W ′ is different from the height of each measurement axis of the wafer laser interferometer 24, the stage controller 19 uses the measured values of the plurality of measurement axes as described above, The amount of rolling is determined, and based on these, the Abbe error in the vertical direction generated when the wafer holder 18 is tilted is corrected.
[0110]
After the end of the above EGA, stage controller 19 moves wafer stage WST to the baseline measurement position in accordance with an instruction from main controller 20. This is because after the EGA is completed and before the exposure operation is started, the measurement axis of the wafer laser interferometer used for measuring the X position of the wafer stage WST is moved from the measurement axis passing through the detection center of the alignment system ALG to the projection optical system PL. This is because it is necessary to switch to the length measurement axis passing through the center of the optical axis, and therefore, it is necessary to accurately measure the baseline, which is the distance between the projection position of the reticle pattern and the detection center of the alignment system ALG.
[0111]
Therefore, main controller 20 detects the first fiducial mark (not shown) formed on fiducial mark plate FM using a TTR (through-the-reticle) alignment system (not shown), and then controls stage controller 19. Then, wafer stage WST is moved through, and a second reference mark (not shown) formed on reference mark plate FM on wafer stage WST is detected using alignment system ALG. That is, the center position of the position of the pair of reticle alignment marks detected by the TTR alignment system is a point representatively showing the projection position of the reticle pattern (the optical axis position of the projection optical system PL), and from this position, the alignment system ALG is used. Is the distance in the X-axis direction and the Y-axis direction to the detection center, that is, the distance moved by the wafer stage WST is the baseline in the X-axis direction and the Y-axis direction. In this case, the reference mark plate FM is made of a low expansion member, and since the positional relationship between the first reference mark and the second reference mark is known, the reticle alignment mark detected by the TTR alignment system and the first reference mark are used. A positional relationship with the mark (positional error), a positional relationship between the detection center of the alignment system ALG detected by the alignment system ALG and the second reference mark (positional error), a design baseline, and a wafer laser interferometer Using the 24 output values, a true baseline can be obtained.
[0112]
Therefore, by moving wafer stage WST by the base line from the position obtained by EGA described above, it is possible to expose each shot area on wafer W ′ so as to be accurately superimposed on the projection position of the reticle pattern. However, in the present embodiment, since scanning exposure is performed, during actual exposure to be described later, the movement of wafer stage WST is moved to the position of the center of the shot where wafer stage WST is moved by the base line from the position obtained by EGA. Is moved to a scan start position (acceleration start position) for exposure of each shot deviated in the scanning direction by a predetermined distance from.
[0113]
Of course, in the above EGA, rotation of the entire wafer, orthogonality, scaling in the X and Y directions are performed based on the positions of the marks corresponding to some of the shot areas without obtaining the array coordinates of all the shot areas. (Magnification error) Only linear errors represented by offsets in the X and Y directions may be obtained, and the shot array data in design may be corrected using the obtained linear errors. In this case, of course, it is necessary to move wafer stage WST based on the position of the shot detected by alignment system ALG and the baseline.
[0114]
In the above baseline measurement, the rotation error between the wafer stage WST and the reference mark plate FM cannot be measured, but in this case, the reference mark plate FM is made of a material having substantially the same thermal expansion coefficient as the wafer stage WST. Since it is configured and fixed firmly with screws or adhesives, there is no possibility that a rotation error occurs between the reflection surface on the side surface of the wafer stage WST and the reference mark plate FM. Further, since yawing of wafer stage WST itself can be corrected based on the measurement value of wafer laser interferometer 24, no inconvenience occurs.
[0115]
After the above-described baseline measurement, the measurement axis in the X-axis direction of wafer laser interferometer 24 used for position control of wafer stage WST is measured from the measurement axis passing through the detection center of alignment system ALG to the optical axis of projection optical system PL. The measurement is switched to the length measurement axis passing through the center, reflecting the baseline measurement result and the yawing measurement result. The switching of the interferometer is performed by the stage controller 19 in response to an instruction from the main controller 20, and after this switching, the stage controller 19 sets the wafer stage WST for the first shot (first shot) exposure. Move to the scanning start position (acceleration start position).
[0116]
Then, exposure by the step-and-scan method is started in the same manner as described above, and the reticle pattern is sequentially transferred to each shot area on the wafer W ′. During this exposure operation, the operation of each unit is managed by the main controller 20 via the stage controller 19, the illumination controller 14, and the like. After the exposure is completed, the wafer W ′ is unloaded in the same manner as the above-described wafer W (see FIGS. 9A to 9C).
[0117]
As described above, in exposure apparatus 100, under the control of stage controller 19 in accordance with the instruction of main controller 20, wafer transfer arm 54, carry-in arm 36 of pre-alignment device 34, carry-out arm 52, wafer stage WST, and the like. The wafer transfer operation is performed by the cooperative operation of the center table 30 and the like. The time during which such cooperative operation is performed, that is, the time from the end of exposure of the wafer W to the loading of the wafer W ′ in the wafer transfer time is a non-exposure time. It is desirable to keep these times as short as possible. In order to shorten the non-exposure time, the transfer speed of the transfer operation of the wafer shown in FIGS. 9A to 9C and FIGS. 10A to 10D should be increased as much as possible. desirable.
[0118]
However, if the transfer speed of the wafer W ′ is too high, the force applied to the wafer W ′ during the transfer increases, and the suction force on the wafer W ′ cannot fully withstand the force, and the position of the wafer W ′ increases. There is a possibility that the positioning accuracy of the wafer W ′ after the stage is input is deteriorated.
[0119]
Therefore, in the exposure apparatus 100, in order to achieve both the positioning accuracy of the wafer W ′ and the improvement of the throughput, the wafer W ′ shown in FIGS. 9A to 9C and FIGS. Various contrivances have been made for the transport operation.
[0120]
FIG. 12A shows a velocity distribution in the descending operation of the loading arm 36 performed from the state shown in FIG. 10A to the state shown in FIG. 10B. In FIG. 12A, the horizontal axis indicates the position of the carry-in arm 36 in the Z-axis direction at the time of descending (this is referred to as “the carry-in arm descending Z position”). The right direction of the horizontal axis is the -Z direction. As shown in FIG. 12A, in the lowering operation of the loading arm 36, for a certain section from the start position of the lowering operation, that is, section L1, in order to increase the lowering speed of the loading arm 36, the loading arm 36 is moved. To accelerate and decelerate. In the section including the position where the wafer W 'is transferred to the center table 30, that is, in the section L2, the transfer arm 36 is lowered at a constant low speed in order to transfer the wafer W' without shifting. I do. Further, after the wafer W 'is sufficiently separated from the hook portions 50a to 50c of the carry-in arm 36 and the wafer W' is completely transferred to the center table 30, a section until a predetermined gap is formed between the wafer W 'and the center table 30, That is, in the section L3, the carry-in arm 36 is accelerated and decelerated again to lower the carry-in arm 36. By finely defining the lowering operation of the loading arm 36 as described above, the delivery of the wafer W ′ from the loading arm 36 to the center table 30 can be performed with high accuracy, and the delivery time can be shortened.
[0121]
FIG. 12B shows a speed distribution of the lowering operation of the center table 30 performed from the state shown in FIG. 10C to the state shown in FIG. 10D. In FIG. 12 (B), the horizontal axis indicates the position of the center table 30 in the Z-axis direction at the time of lowering (this is referred to as “center table lowering Z position”), and the right direction of the horizontal axis indicates the −Z direction. Has become. As shown in FIG. 12B, in the lowering operation of the center table 30, for a certain section from the start position of the operation, that is, in the section L4, the center table 30 is moved in order to increase the lowering speed of the center table 30. Acceleration and deceleration. In the section including the position where the wafer is transferred from the center table 30 to the wafer holder 18, that is, in the section L5, the center table 30 is moved down at a constant low speed in order to transfer the wafer W 'without causing a positional shift. ing. By defining the lowering operation of the center table 30 as described above, the transfer of the wafer W ′ from the center table 30 to the wafer holder 18 can be performed with high accuracy, and the transfer time can be shortened.
[0122]
The acceleration / deceleration operation described above makes it possible to shorten the transfer time while maintaining the accuracy of the transfer of the wafer. However, in order to substantially reduce the transfer time, for example, the acceleration in the section L1 and the section L3, It is desirable to increase the maximum speed, the deceleration, and the speed in the section L2 as much as possible. However, considering the delivery accuracy, there is a limit to their size, and the limit is considered to vary from device to device (unit).
[0123]
Therefore, in this embodiment, the acceleration, the maximum speed, the deceleration in the section L1 and the section L3, the speed in the section L2, the position at which the vacuum suction of the loading arm 36 is released (wafer transfer position), and the like can be adjusted as device parameters. By adjusting these parameters before actually operating the exposure apparatus 100 or during maintenance of the exposure apparatus 100, the parameters can be optimized for each apparatus.
[0124]
As shown in FIG. 12A, the parameters defining the lowering operation of the loading arm 36 include the acceleration P of the loading arm 36 in the section L1. ₁ , Maximum speed P ₂ , Deceleration P ₃ And the descending speed P of the loading arm 36 in the section L2. ₄ And the acceleration P of the loading arm 36 in the section L3. ₅ , Maximum speed P ₆ , Deceleration P ₇ And the offset of the carry-in arm lowering Z position for releasing the vacuum suction of the carry-in arm 36 (hereinafter, referred to as “the carry-in arm vacuum-off position offset”) P ₈ And the distance P from the position where deceleration is completed in the section L1 to the carry-in arm vacuum-off position. ₉ And the distance P from the carry-in arm vacuum-off position to the position at which acceleration starts again in the section L3. ₁₀ and so on. The length of the sections L1 to L3 is determined by the parameter P ₁ ~ P ₁₀ Is determined by the set value of. Table 1 below shows device parameters for the lowering operation of the loading arm 36. The vertical movement / rotation mechanism 38 that lowers the loading arm 36 is a mechanism driven by rotation of a motor. Therefore, in Table 1, parameter names for acceleration, speed, and deceleration in the lowering operation of the loading arm 36 are shown. Are expressed as “〜motor rotation acceleration”, “〜motor rotation speed”, and “〜motor rotation deceleration”. In addition, a measurement tool for measuring the position of the carry-in arm vacuum-off position has conventionally been provided, and by using the measurement tool, an optimal carry-in arm vacuum-off position can be measured. . In Table 1 below, the parameter P ₈ Is referred to as “load-in arm vacuum-off position offset” when the vacuum-off position of the load-in arm 36 is turned on when the vacuum of the center table 30 is turned on (the wafer W ′ is attracted to the center table 30, This is because the Z position of the carry-in arm 36 (when the vacuum pressure of the table 30 is equal to or more than a predetermined value) is managed as a position where a predetermined offset value is placed, and this offset value is used as a parameter. This offset value corresponds to a value obtained by adding the following two times.
[0125]
1). Delay time from when the measurement tool detects the vacuum on the center table 30 to when the Z position of the transfer arm 36 is detected
2). Offset time so that the time when the vacuum of the center table 30 is turned on is immediately before the time when the vacuum of the loading arm 36 is completely turned off.
[0126]
2). Will be described in more detail. When the wafer W ′ is transferred from the carry-in arm 36 to the center table 30 (when the vacuum of the center table 30 is turned on), if the vacuum of the carry-in arm 36 is completely off, the wafer W ′ is transferred to the center table 30. It shifts sideways on the top. Conversely, if the time from when the vacuum of the center table 30 is turned on until the vacuum of the carry-in arm 36 is completely turned off is long, the peripheral portion of the wafer W ′ is pulled by the carry-in arm 36, and When the vacuum is completely turned off, the wafer W 'vibrates on the center table 30, causing a displacement. Therefore, when the vacuum of the center table 30 is turned on, it is immediately before the vacuum of the carry-in arm 36 is completely turned off in order to transfer the wafer W ′ from the carry-in arm 36 to the center table 30 without displacement. Very important. Therefore, the parameter P for adjusting this timing ₈ Is very important.
[0127]
Specifically, it is optimal to set the time from when the vacuum of the center table 30 is turned on to when the vacuum of the carry-in arm 36 is completely turned off to about 20 msec. The time from when the carry-in arm 36 starts to be vacuum-off until it is completely turned off varies depending on the machine, but is about 80 to 100 msec. Therefore, 2). The optimal time is about 60 to 80 msec.
[0128]
This parameter P ₈ Is adjusted to an appropriate value, for example, even if the wafer transfer position of the center table 30 changes with time due to backlash or settling, it is possible to absorb the change, and therefore always adjust at the optimal timing. The wafer W ′ can be transferred to the center table 30.
[0129]
[Table 1]

[0130]
In Table 1 above, the unit of “の rotational speed” is “rps”, and the unit of “「 rotational acceleration ”or“ 〜rotational deceleration ”is“ rpss ”, but“ rps ”is 1 second. "Rpss" means "the amount of change in the number of rotations of the motor per second".
[0131]
Further, as parameters defining the lowering operation of the center table 30, as shown in FIG. 12B, the acceleration P of the center table 30 in the section L4 is used. ₁ , Maximum speed P ₂ , Deceleration P ₃ And the lowering speed P of the center table 30 in the section L5. ₄ , Deceleration P ₅ And a distance P from the position where deceleration is completed in the section L4 to the center table lowering Z position where the vacuum holding of the center table 30 is released (hereinafter, referred to as “center table vacuum off position”). ₆ And the center table vacuum off position offset P ₇ There is. The length of the sections L4 and L5 is determined by the parameter P ₁ ~ P ₇ Is determined by the set value. Table 2 below shows device parameters for the lowering operation of the center table 30. In addition, since the actual drive mechanism for lowering the center table 30 is a cam mechanism and a link mechanism driven by rotation of a motor, in Table 2, the parameter names for the acceleration, speed, and deceleration of the center table 30 are "~". Motor rotation acceleration "," -motor rotation speed ", and" -motor rotation deceleration ".
[0132]
Note that the parameter P ₇ Is "CT vacuum off position offset" because the parameter P ₈ Is the “load-in vacuum offset position” for the same reason as described above, and the relationship between the “load-in arm 36” and “center table 30” is simply the relationship between “center table 30” and “wafer holder 18”. It just turned into a relationship.
[0133]
[Table 2]

[0134]
Each parameter P that defines the above-described transport operation ₁ ~ P ₁₀ Needs to be adjusted before the exposure apparatus 100 is actually operated, that is, before the exposure step is performed by the wafer transfer operation and the exposure operation. Therefore, in this embodiment, in a state where the exposure apparatus 100 is actually operable and a wafer can be loaded, an automatic parameter adjustment process is executed as a parameter adjustment method before actual operation is started. .
[0135]
In the present embodiment, the positioning accuracy of the wafer to be loaded and the time required for transporting the wafer are used as a scale for adjusting the parameters. The positioning accuracy of the wafer can be detected by placing the wafer on the stage and then detecting the position information of the mark formed on the wafer held on the wafer holder 18 by the alignment system ALG. For example, if the wafer to be loaded has already been exposed to the first layer, the search alignment marks SYM and SθM described above are formed on the wafer. The positional information of the mark is imaged, and the positional deviation amounts (ΔX, ΔY) and the rotational deviation amounts (Δθ), which are the measures of the positioning accuracy of the wafer, can be calculated based on the positional information.
[0136]
As described above, if the values of the positional deviation amounts (ΔX, ΔY) and the rotational deviation amount Δθ are too large, it becomes difficult to fit the detection target mark in the imaging field of view of the alignment system ALG. Therefore, in such a situation, it becomes impossible to perform accurate exposure, and it is necessary to reload the wafer, and the throughput is extremely reduced. Therefore, in the present embodiment, as shown in Table 3 below, the input reproducibility (ΔX (3σ), ΔY (3σ), Δθ (3σ) of the wafer positional deviation (ΔX, ΔY) and the rotational deviation Δθ. ), (ΔY−Δθ) (3σ)) and the range from the maximum value to the minimum value of the deviation amount (ΔX (Max−Min), ΔY (Max−Min), (ΔY−Δθ) (Max−Min)) With the wafer input performance evaluation factor F _i (I = 1 to 9) to adjust the parameters. In the present embodiment, the parameters are adjusted based on the input reproducibility of the deviation amount (ΔX, ΔY, Δθ) from the design position. However, the present invention is not limited to this, and for example, regardless of the design position. Alternatively, the parameters may be simply adjusted based on the reproducibility of the wafer input position (X, Y, θz).
[0137]
[Table 3]

[0138]
Note that F ₉ That is, during the wafer loading time, the wafer stage WST moves to the wafer exchange position, and after the wafer W on the wafer holder 18 is collected, the wafer W ′ held by the loading arm 36 is loaded onto the wafer holder 18 and This is the time until vacuum suction on the substrate starts.
[0139]
In the present embodiment, the parameters are optimized using the damped least squares method. Specifically, the evaluation factor F as shown in the following equation (1) _i An evaluation function Φ composed of terms including (i = 1 to m, here, m = 9) is set, and a setting parameter when the value of the evaluation function Φ becomes minimum is set as an optimal parameter.
[0140]
(Equation 1)

[0141]
Where w _i Is the weight for each evaluation factor,
[0142]
[Outside 1]

[0143]
Is a target value of each evaluation factor, which is a preset value. Also, ΔP _j (J = 1 to n, where n = 7 or 10) is a change amount of each parameter. The term including D is a term incorporated in the evaluation function when the damped least squares method is applied. When this term is incorporated in the evaluation function, this term plays a role of a so-called damper that prevents the solution from jumping out of the linear approximation range, and the solution that minimizes the evaluation function Φ largely deviates Is prevented. Therefore, hereinafter, this term is referred to as a damping term, and the coefficient D is referred to as a damping factor.
[0144]
The evaluation function Φ may be expressed by the following equation (2).
[0145]
(Equation 2)

[0146]
Equation (2) differs from Equation (1) only in the damping term. That is, in the equation (2), the value of the damping factor multiplied by the change amount can be set to a different value for each parameter.
[0147]
In the present embodiment, each parameter is optimized by the sequential approach. In this sequential approach, first, several combinations of values are set as combinations of parameter setting values, and each time the combinations are sequentially set in the exposure apparatus 100, a wafer is loaded. Then, the wafer positioning accuracy (F ₁ ~ F ₈ ) And wafer loading time (F ₉ ) Is calculated to calculate the value of the evaluation function Φ described above, and the combination of the parameter setting values when the value is the smallest is determined as the optimal solution at that time. Further, for each new combination of parameter setting values based on the optimal solution, the wafer input, the measurement of the execution result, and the calculation of the value of the evaluation function Φ are performed. If there is a combination of parameter setting values whose values are smaller than the evaluation function Φ whose value was the last time, the process of setting the combination as a new optimal solution is repeatedly performed several times to obtain the parameter. Is a method of sequentially approaching the true optimal solution of the combination of the set values of.
[0148]
Hereinafter, the parameter adjustment operation of the exposure apparatus 100 of the present embodiment will be described with reference to other drawings as appropriate according to a flowchart shown in FIG. 13 which simplifies a processing algorithm of the CPU in the main controller 20. . In the following description, a case will be described in which the parameters shown in FIG. 12A and Table 1 are adjusted.
[0149]
As shown in FIG. 13, first, in step 101, parameters to be adjusted are selected. All of the parameters shown in FIG. 12A and Table 1 do not uniformly contribute to wafer positioning accuracy. For example, P shown in FIG. ₈ (Load arm vacuum-off position offset) and P in section L2. ₄ (The rotation speed of the carry-in arm motor at the time of transfer) is considered to have the greatest influence on the positioning accuracy of the wafer. ₃ , P ₉ , P ₁₀ Are considered to significantly affect the positioning accuracy of the wafer. ₁ , P ₂ , P ₅ , P ₆ , P ₇ It is considered that the influence on the positioning accuracy of the wafer is small.
[0150]
In step 101, some parameters to be adjusted are selected (specified) from the parameters shown in Table 1. That is, in the present embodiment, parameters to be adjusted are selected instead of adjusting all the parameters shown in Table 1 at once. Such parameter selection is desirably performed according to the degree of contribution (degree of influence) of the parameter to the value of the evaluation function Φ. For example, a wafer transfer section, that is, a parameter (P ₃ , P ₄ , P ₈ , P ₉ ) Is considered to be more important to the value of the evaluation function Φ than the other parameters. ₃ , P ₄ , P ₈ , P ₉ ) Shall be selected. Note that such parameter selection may be performed via a keyboard (not shown) provided in the main control device 20, or each parameter may be previously grouped in the storage device 21 according to its importance. The main control unit 20 may read out the group of parameters having the highest importance. In the latter case, the labor of the operator can be reduced, and the time required for the parameter adjustment operation can be shortened.
[0151]
Next, in step 103, a measurement type or the number of optimization steps is designated. The measurement type refers to a rough / fine measurement mode and a fine measurement mode to be described later, and the number of optimization steps refers to the number of approaches to the optimal solution in the above-described sequential approach.
[0152]
The evaluation factors in the evaluation function Φ used for optimizing this parameter include the wafer reproducibility (3σ) shown in Table 3, and the wafer reproducibility is calculated as data in order to calculate the wafer reproducibility as data. It is necessary to input several times. The reliability of the input reproducibility data increases as the number of wafer inputs, ie, the number of measurements, increases. However, the more the number of measurements, the longer it takes time to calculate the input reproducibility data. Therefore, in the exposure apparatus 100 of the present embodiment, initially, the number of times of wafer introduction is reduced, the reproducibility of wafer introduction is measured with a relatively small number of introductions, and the optimal solution of the parameters is roughly detected. A rough / fine measurement mode is provided in which the number of times of wafer introduction is increased and an optimal solution of the parameter is obtained with high accuracy. Whether to use the rough / fine measurement mode or only the fine measurement mode may be specified via a keyboard (not shown), or the mode is set in advance as an apparatus parameter. Main controller 20 may determine whether to perform the rough / fine measurement by referring to the parameter. If the rough / fine measurement has been selected (or selected), in step 103, for example, the rough / fine measurement internal flag assigned to the internal memory area is turned on. If the rough / fine measurement mode is not set as a parameter, the internal flag of the rough / fine measurement is turned off so that the normal number of times of measurement (ie, only the fine measurement) is performed. Here, it is assumed that the rough / fine measurement mode has been selected.
[0153]
In step 103, the number of optimization steps is specified as the number of times to sequentially approach the optimal solution of the parameter setting value in the above-described sequential approach. Here also, the number of optimization steps may be set via a keyboard (not shown), or is specified in the storage device 21 as a device parameter, and the main control device 20 determines the value of this device parameter. You may make it read.
[0154]
Next, in step 105, the boundary conditions of the parameters selected in step 101 are set. In step 101, as described above, the parameter (P ₃ , P ₄ , P ₈ , P ₉ If () is selected, in step 105, the boundary conditions of the set values of these parameters are set. The boundary condition defines a range in which parameter setting values can be taken. Combinations of parameter setting values, which will be described later, are all determined within a range having the boundary condition as an upper limit and a lower limit. Here, a plurality of combinations of the set values of the specific parameters are determined based on the predetermined set values of the specific parameters. In this case, the parameter P ₃ , P ₄ , P ₈ , P ₉ Are calculated. For example, the parameter P ₃ , P ₄ , P ₈ , P ₉ Is set to (3D, 4D, 8D, 9D), a combination of several set values based on (3D, 4D, 8D, 9D) is determined. For example, if a value (3D ± ΔT, 4D ± ΔT, 8D ± ΔT, 9D ± ΔT) different from (3D, 4D, 8D, 9D) by a predetermined value ± ΔT is considered as an element of each combination of parameters, (3D− When one set value is selected from each of ΔT, 3D, 3D + ΔT, (4D−ΔT, 4D, 4D + ΔT), (5D−ΔT, 5D, 5D + ΔT), and (6D−ΔT, 6D, 6D + ΔT) (For example, a combination of (3D + ΔT, 4D-ΔT, 5D, 6D-ΔT)) ₃ C ₁ × 4), the combination of the parameter setting values can be determined. As the predetermined set value, a design value obtained in advance by a device constant may be used.
[0155]
Next, in step 107, the value of the damping factor D is set. The damping factor D can also be set by a keyboard, or is set as a device parameter, and can be set by reading the value stored in the storage device 21 by the main control device 20. Note that, in this case, when Expression (1) is used as the evaluation function Φ, only one damping factor D is read from the storage device 21, and when Expression (2) is used, the damping factor D is selected in Step 101. A damping factor corresponding to each parameter is read from the storage device 21.
[0156]
Next, in step 109, a predetermined number of wafers are loaded. As the predetermined number of times, a numerical value input by a keyboard or a numerical value set in advance as an apparatus parameter is used. In the present embodiment, since the rough / fine measurement mode is prepared in the parameter adjustment, it is assumed that the number of times of wafer input at the time of rough measurement and the number of times of wafer input at the time of fine measurement are set as device parameters. . If the rough / fine measurement mode has been set in step 103, first, the number of times of wafer input during rough measurement is set as a predetermined number.
[0157]
This wafer loading is performed in the same manner as the above-described operations shown in FIGS. 8A to 8D, 9A to 9C, and 10A to 10D. In the search alignment operation, the position shift amounts (ΔX, ΔY) and the scale of the positioning accuracy of the wafer at that time are measured for the wafer held in the wafer holder 18 by the same operation as the above-described detection of the search alignment mark. The rotation deviation amount Δθ is calculated each time a wafer is loaded.
[0158]
Next, in step 111, the main controller 20 determines the wafer insertion evaluation factor F shown in Table 3 based on the positional deviation amount (ΔX, ΔY) and the rotational deviation amount Δθ for a predetermined number of wafer insertions. _i (I = 1 to 9) are calculated, the value of the evaluation function Φ in the combination of the current parameter setting values is calculated, and the value is stored in the storage device 21. The change amount ΔP of each parameter of the above-described damping term included in the evaluation function Φ _j , Because the set values of each parameter are still the initial values, ΔP _j Is set to 0, and the value of the evaluation function Φ is calculated.
[0159]
In step 113, it is determined whether the value of the evaluation function Φ has been calculated for all combinations of the parameter setting values (whether all combinations have been executed). Here, since the evaluation function Φ has been calculated for only one combination, the determination here is denied, and the routine proceeds to step 115.
[0160]
In step 115, the combination of the set values of the parameters to be set in the apparatus is changed to a combination in which the value of the evaluation function Φ has not been calculated, and the process returns to step 109.
[0161]
Thereafter, in step 113, the processing of step 109 → step 111 → step 113 → step 115 is repeatedly executed until it is determined that the value of the evaluation function Φ has been calculated for all the combinations of the set values of the parameters. The value of the evaluation function Φ in the combination is calculated in step 111. When calculating the evaluation function Φ in step 111, the change amount ΔP of each parameter in the damping term of the evaluation function Φ _j , The difference between the previous set value of the parameter and the current set value may be set.
[0162]
After the determination in step 113 is affirmed, in step 117, the combination having the minimum value is extracted from the evaluation functions Φ calculated for all the combinations of the parameter setting values. The processing of steps 109 to 115 repeatedly performed until the determination in step 113 is affirmed is included in the first step.
[0163]
Next, in step 119, when the value of the evaluation function Φ of the combination extracted in the current step 117 is smaller than the value of the evaluation function Φ of the combination extracted so far, the combination of the optimal value of the parameter; That is, the parameter optimum solution is updated to the combination extracted in step 117 at this time. Since the calculation of the combination in step 117 this time is the first (first step) calculation, here, the parameter optimum solution calculated this time is set, and the process proceeds to step 121.
[0164]
Next, at step 121, it is determined whether or not the sequential approach processing has been executed for the designated number of steps (optimized step number) set at step 103. The specified number of steps indicates the number of steps that sequentially approach the optimal solution of the combination of parameters as described above. For example, if the number of specified steps is five, only one step has been executed here. , The determination is denied, and the routine proceeds to step 123. Step 117 → step 119 → step 121 is included in the second step.
[0165]
Next, in step 123, a new combination different from the combination of the parameter setting values for which the evaluation function Φ has been calculated is created. This new combination is created on the basis of the combination of the optimum values of the parameters updated (set) in step 119 described above. For example, a combination of some values appropriately extracted from values within a predetermined range centered on the combination of the optimal values of the parameters updated (created) in step 119 is a combination of a new set value. Created as The created combination is stored in the storage device 21. After execution of step 123, the process returns to step 109.
[0166]
In this embodiment, if the determination is negative in step 121, the process returns to step 109 after execution of step 123. However, if the determination is negative in step 121, the process does not proceed to step 123. Alternatively, the process may return directly to step 105. In this case, the parameter boundary condition can be newly set in step 105, and the damping factor can be reset in step 107 thereafter, so that finer adjustment can be realized. Will be able to However, in the present embodiment, from the viewpoint of shortening the processing time, after a negative determination is made in step 121, the process proceeds to step 123 and returns to step 109.
[0167]
Thereafter, until the determination in step 113 is affirmed, the processing of step 109 → step 111 → step 113 → step 115 is repeatedly executed, and the value of the evaluation function Φ in all combinations is calculated in step 111.
[0168]
After the determination in step 113 is affirmed, in step 117, the combination having the minimum value is extracted from the evaluation functions Φ calculated for all the combinations.
[0169]
Next, in step 119, if any of the values of the evaluation function Φ of the combination extracted in step 117 this time is smaller than the value of the evaluation function Φ of the combination extracted so far, The combination of the optimum values, that is, the parameter optimum solution is updated to the combination extracted in the current step 117. Since the calculation of the combination in step 117 this time is the second (second step) calculation, here, the value of the evaluation function Φ corresponding to the parameter optimum solution calculated in step 117 of the previous (first) step is used. If the value of the evaluation function Φ calculated this time is smaller than this, the parameter optimum solution is updated to the current parameter optimum solution.
[0170]
Next, at step 121, it is determined whether or not the processing (sequential approach) has been executed for the specified number of steps set at step 103. This optimal step number indicates the number of steps that sequentially approach the optimal solution of the combination of parameters as described above. Here, since only two steps have been executed, the determination is denied, and the routine proceeds to step 123.
[0171]
Thereafter, the loop processing of step 109 → step 111 → step 113 → step 115 and step 117 → step 119 are performed until the determination in step 121 is affirmed, that is, until the sequential approach to the parameter optimal solution for the designated step is completed. → The processing of step 121 → step 123 is repeatedly executed, and in step 119, a sequential approach of the parameter optimal solution of a predetermined number of steps is executed.
[0172]
Next, in step 125, main controller 20 reads the values of evaluation function Φ corresponding to all combinations of the parameters calculated so far, and determines that the value of evaluation function Φ of the current parameter optimum solution is the minimum value among them. Check if it is.
[0173]
Then, in step 127, it is confirmed whether or not the rough / fine measurement mode has been selected as the measurement mode by referring to whether or not the above-described rough / fine measurement internal flag is on. If only the rough measurement is currently being performed, the determination is affirmative and the process returns to step 105. If the measurement mode is not the rough / fine measurement mode, or if the measurement mode is the rough / fine measurement mode and the fine measurement mode is ended, the determination is negative and the process proceeds to step 129. Here, since only the rough measurement has been performed, the determination is denied, and the process returns to step 105.
[0174]
Thereafter, after the fine measurement mode is set again, that is, the number of times of loading of the wafer is set to the fine measurement, the processing from step 105 to step 125 is executed, and the process returns to step 127 again. In this case, since fine measurement has already been performed, the determination is denied, and the routine proceeds to step 129.
[0175]
Next, in step 129, the parameter optimal solution finally determined, that is, the optimal value of the parameter setting value is set (third step). Thereby, the parameter (P ₃ , P ₄ , P ₈ , P ₉ ) Is actually set in the exposure apparatus 100, and thereafter, the wafer input of the exposure apparatus 100 is executed with this set value.
[0176]
Next, in step 131, it is determined whether to change the parameter. Here, of all the parameters, the parameter (P ₃ , P ₄ , P ₈ , P ₉ ), The determination is affirmative and the process returns to step 101.
[0177]
In the present embodiment, it is not always necessary to optimize all the parameters shown in Table 1, and only the parameters having a high influence described above may be adjusted. In this case, the determination is negative and the process ends.
[0178]
In step 101, parameters to be adjusted (for example, parameter P ₁ , P ₂ , P ₅ , P ₆ , P ₇ , P ₁₀ ) Is selected, and thereafter, the processing of steps 103 to 131 is executed in the same manner as described above. When the adjustment of all parameters is completed in this way, the determination in step 131 is denied, and the process ends.
[0179]
By executing the above-described parameter adjustment operation at the time of start-up or maintenance, the parameters defining the wafer loading operation are optimally adjusted. After the operation of the exposure apparatus 100, the parameters adjusted by the optimally adjusted parameters are used. 10 (A) to 10 (B), the lowering operation of the carry-in arm 36 can be executed.
[0180]
The parameters of the center table 30 shown in FIG. 12B and Table 2 are also set by the above-described operation according to the flowchart shown in FIG. Can be optimized. Also in this case, in step 101, parameters for which optimization is actually executed are selected from all the parameters in descending order of the degree of influence. For example, in FIG. 12B, the parameter that most affects the wafer loading accuracy is P ₄ , P ₆ , P ₇ Therefore, these parameters should be selected in the first step 101, and other parameters should be selected as needed in the subsequent step 101.
[0181]
As described above in detail, in the present embodiment, in step 111, an evaluation function having a term using information on the operation result of the exposure apparatus 100 as an evaluation factor for each of a plurality of combinations of the set values of at least two specific parameters. Calculate the value of Φ. Then, in step 117, for example, a combination in which the value of the evaluation function is the smallest, for example, is determined as an optimal combination, and an optimal value included in the optimal value combination is set as each set value of the specific parameter. The exposure apparatus 100 is set. That is, if the parameter adjustment method of the present embodiment is executed, the optimal values of the set values of the plurality of specific parameters are automatically determined based on the evaluation function Φ having a term using the information on the operation result of the exposure apparatus 100 as an evaluation factor. , The parameters can be optimized with high accuracy in a short time.
[0182]
Further, in the present embodiment, the loop processing of step 109 → step 111 → step 113 → step 117 → step 119 → step 121 → step 123, that is, in the second step, the optimum value of the parameter is sequentially approached to the true optimum solution. Since a so-called sequential approach can be used, optimization of parameters can be surely achieved.
[0183]
Therefore, after the above-described parameter adjustment operation is performed, the wafer can be transported based on the optimally adjusted parameters and placed on wafer stage WST, so that the wafer can be transported efficiently. . That is, in the exposure apparatus 100 of the present embodiment, the parameters adjusted optimally can expose the wafer held on the stage, so that the overlay accuracy of the shot areas of the wafer can be improved, so that high accuracy For a short time.
[0184]
Further, in the present embodiment, a so-called damped least squares method for optimizing parameters based on an evaluation function Φ having a damping term including a damping factor D is used. In this way, when this damping term is obtained by using the least squares method in a state outside the range of the linear approximation, it plays a role of preventing the solution from being largely deviated, The optimum solution for each parameter can be reliably obtained. In this embodiment, the least squares method may be used instead of the attenuation least squares method. In this case, for example, the parameter adjustment operation shown in FIG. 13 may be performed using Expression (3) shown below as an evaluation function Φ. There is no damping term in this equation (3).
[0185]
[Equation 3]

[0186]
If the evaluation function of Expression (3) is used, for example, in step 125, the value of the evaluation function Φ in the initial state before parameter optimization is read out, and the value of the evaluation function Φ after parameter optimization becomes smaller. Can be a method of confirming that the Further, in the present embodiment, as shown in Table 3, the reproducibility of the positioning accuracy of the wafer in the search alignment in a plurality of wafer introductions, the range thereof, the wafer transfer time, and the like are evaluated by the evaluation factor F of the evaluation function Φ. _i However, the present invention is not limited to this. The deviation (rotation, orthogonality, scaling in the X and Y directions (magnification error)) between the wafer coordinate system and the stage coordinate system calculated by wafer alignment, X , Y-direction offset) may be used as an evaluation factor of the evaluation function Φ. The evaluation factor may be any factor that indicates the reproducibility and range of the wafer positioning accuracy. But it's fine.
[0187]
Further, in the present embodiment, the number of times of the wafer input operation of the exposure apparatus 100 is reduced, the optimum value of the specific parameter is roughly detected, and the approximate approach to the true optimum solution is performed. By increasing the number of wafer loading operations, a true optimum solution for the set value of each parameter is obtained with high accuracy. Therefore, it is possible to reduce the overall number of operations of the apparatus until obtaining the optimal solution of a specific parameter, as compared with increasing the number of operations of wafer input from the beginning and detecting the optimal solution in close inspection, and The time required for adjustment can be reduced.
[0188]
Further, in the present embodiment, among the plurality of parameters, the parameters are adjusted in a state in which the number of parameters is appropriately limited in the descending order of the degree of influence on the operation result of the apparatus, so that optimization of each parameter is impossible. Without any adjustments. The selection of the parameter is determined by the parameter (P ₃ , P ₄ , P ₈ , P ₉ ) Does not need to be selected, and the parameter (P ₄ , P ₈ ) Alone or other combinations. In the present embodiment, a plurality of parameters (P ₃ , P ₄ , P ₈ , P ₉ ) Were performed with all the set values changed, for example, the parameter P ₈ Parameter P in order to set only the optimal value ₈ May be changed and the parameter adjustment operation shown in FIG. 13 may be executed.
[0189]
Further, in the above embodiment, the parameter adjustment operation performed at the time of starting up the apparatus, at the time of maintenance, and the like has been described. However, the present invention is not limited to this. For the case where the positioning accuracy is deteriorated, the parameters may be optimized simultaneously with the actual execution of the exposure step.
[0190]
By the way, if the parameter adjustment operation shown in FIG. 13 is performed during the execution of the exposure process, the throughput may be reduced. Therefore, when the parameters are adjusted even during the exposure process, it is desirable to perform the following.
[0191]
First, in substantially the same manner as in the above-described embodiment, at the time of start-up and maintenance of the apparatus, the reproducibility and range of the loading result when a plurality of wafers are loaded for each of a plurality of combinations of parameter setting values are obtained. Based on the above, the value of at least one evaluation function Φ of the above-described equations (1) to (3) is calculated for each combination. Then, a table showing the correlation between the change in the parameter set value and the change in the value of the evaluation function Φ is created and stored in the storage device 21 (table creation step).
[0192]
After the operation of the apparatus, a predetermined number of wafers (for example, one lot) are conveyed by the above-described operation, and each time the wafers are loaded on the stage, the evaluation function Φ based on the above-described search alignment result and the like calculated. Is determined to be worse (increased), for example, is greater than a predetermined threshold value. If the determination is affirmative, it is stored in the storage device 21. By referring to the relative relationship between the evaluation function Φ shown in the above-mentioned table and the variation of the parameter setting value, the parameter setting value is changed in a direction in which the value of the evaluation function Φ decreases. In this way, every time a predetermined number of wafers are carried by the carry-in arm 36, information about the result of wafer transfer is detected, the value of the evaluation function Φ at that time is calculated, and the set value of the parameter is evaluated. It is adjusted to an optimum value based on the value of the function Φ. That is, in the present invention, even if the optimum value of the parameter changes due to the aging of the apparatus, the set value of the parameter can be constantly adjusted to the optimum value. Further, since the optimum value of the specific parameter can be obtained only by referring to the table, the parameter can be adjusted without lowering the throughput even during the exposure process.
[0193]
In addition, the parameter adjustment method of the above embodiment is effective not only for adjusting parameters that define the transfer operation of a transfer system such as the carry-in arm 36 and the center table 30, but also, for example, for the direction of the wafer in the pre-alignment device 32. It is also effective for adjusting parameters that define a detection operation for detecting a position shift, and for adjusting parameters (for example, a scan speed, an exposure amount given to the wafer W, and a focus offset) that define an exposure operation of an exposure apparatus. .
[0194]
For example, the pre-alignment device 32 measures the outer edge illuminated from below with the measuring units 40a to 40c to detect the misalignment of the orientation and the center position of the wafer. As described above, an image pickup device such as a CCD camera is generally used, and image data picked up by the image pickup device is used to detect the above-described positional shift. The contents of the image data greatly change depending on how the wafer is illuminated. In particular, in a 6 o'clock direction imaging device having a notch, since the outer shape of the wafer to be imaged is complicated, the light emitting state of the LED as the light source 55 (for example, the occurrence of a local high-brightness portion at the outer edge of the wafer) Or scattered light or light leaking from the notch) may significantly change the measurement accuracy of the outer shape of the wafer.
[0195]
Accordingly, the present invention provides an evaluation function that uses the measurement reproducibility (3σ) and the range of measurement values (maximum value−minimum value) of the angle shift and the position shift of the wafer measured by the pre-alignment device 32 as evaluation factors, and 5 and the waiting time from the lighting of the LED to the measurement (measurement when the luminance of the LED after lighting is unstable). The parameter measurement is performed using the same operation as in the flowchart shown in FIG. 13 with parameters such as (parameters for preventing) as parameters to be adjusted, so that the image measurement accuracy can be improved. That is, the present invention can also be applied to optimization of a parameter that defines a detection operation of a detection system that detects position information of an object. Further, the present invention can be applied to parameter adjustment of a mechanism for roughly adjusting the X-axis direction, the Y-axis direction, and the direction of the notch of the wafer before the wafer is placed on the wafer transfer arm 54. .
[0196]
Further, in the above-described embodiment, adjustment of parameters defining the lowering operation of the loading arm 36 and the lowering operation of the center table 30 shown in FIGS. 10A to 10D, that is, the operation at the time of wafer loading is specified. Although the adjustment of the parameters has been described, the present invention can also be applied to the adjustment of the parameters defining the unload operation of the wafer. For example, it is also used to adjust the parameters that define the lifting operation and the suction releasing operation of the center table 30 shown in FIGS. 9B to 9C, the movement of the carry-out arm 52 in the Y-axis direction, and the suction starting operation. The present invention can be applied. At this time, for example, the positioning accuracy of the wafer detected by the wafer position detecting mechanism in the substrate processing apparatus in which the wafer has been transferred from the unloading arm 52 of the exposure apparatus 100 and the transfer time to reach the wafer are factors for evaluating the evaluation function. It becomes.
[0197]
Further, in the above embodiment, the parameters are actually adjusted based on the operation result when the wafer is loaded into the exposure apparatus 100. However, the parameter adjustment is performed based on the apparatus constant of the exposure apparatus 100, installation conditions, and the like. A simulation of a wafer loading operation is performed by a mathematical model of the exposure apparatus 100 built on a computer, and information on an operation result of the apparatus calculated by the simulation (each evaluation factor F shown in Table 3). _i ) May be used to determine the evaluation function Φ from the estimated value and adjust the parameters.
[0198]
In the above embodiment, the measurement result of the search alignment is used as the evaluation factor in the evaluation function Φ. However, the present invention is not limited to this. For example, the wafer coordinate system and the stage coordinate system in the EGA described above are used. The reproducibility and range of deviation (rotation, offset, scale) from the above may be used as the evaluation factors.
[0199]
Further, in the above embodiment, the method of adjusting the parameters defining the wafer transfer operation has been described, but it goes without saying that the present invention can be applied to the reticle transfer operation or the measurement operation.
[0200]
Note that the wafer pre-alignment apparatus is not limited to the one described in the above embodiment, and various forms can be used. For example, as disclosed in Japanese Patent Application Laid-Open No. 9-36202, an illumination system is mounted on the wafer stage WST, and after the wafer stage WST comes under the loading arm 36, the illumination system is mounted using the illumination system mounted on the wafer stage WST. A configuration for performing alignment may be adopted. Alternatively, the light may be illuminated from above the wafer with the light emitting element, and the light receiving element may be arranged below the wafer to detect the transmitted light. As described above, various methods can be used for the pre-alignment detection. In any case, the exposure operation is completed, the wafer stage WST is moved to the wafer exchange position for wafer exchange, and the unloading operation is performed. Pre-alignment measurement can be performed in parallel with
[0201]
As described above, various forms of the pre-alignment mechanism configured by the wafer pre-alignment apparatus and the like can be considered. For example, as shown in FIGS. 14A to 14C, the hook portions 50a to 50h of the carry-in arm 36 are provided on the wafer stage WST or the wafer holder 18 without providing the center table 30 that can be moved in and out of the wafer holder. A pair of concave grooves 31a, 31b through which 50c can pass, and notches 30a to 30b are formed, and the carry-in arm 36 and the wafer stage WST cooperate with each other without interfering with the carry-in arm 36 and the wafer stage WST. The transfer of the wafer may be performed.
[0202]
Further, in a state in which the center table 30 which can be moved in and out of the wafer holder is provided, a configuration in which the center table 30 is directly transferred from the wafer transfer arm 54 to the center table 30 without providing the pre-alignment device 32 may be adopted. In any case, by optimizing the parameters for defining the wafer loading operation according to the present invention, it is possible to realize wafer transfer that achieves both accuracy and throughput of various transfer systems.
[0203]
In this specification, the “arm” is a broad concept including a member used for holding a substrate (a wafer in the above embodiment) as an object when the substrate is transferred.
[0204]
That is, in the above embodiment, an LSA (Laser Step Alignment) system or the like can be applied in addition to the FIA system as the alignment system ALG as the detection system of the value of the evaluation factor of the evaluation function Φ. The LSA system is the most versatile sensor that irradiates a laser beam to a mark and measures the position of the mark to be detected by using the diffracted and scattered light. ing. In addition, as the alignment system ALG, for example, an alignment sensor that irradiates a mark to be detected with coherent detection light and interferes two diffracted lights (for example, the same order) generated from the mark to detect the mark alone is used. Alternatively, it can be used in combination with the above-mentioned FIA type, LSA type and the like as appropriate.
[0205]
In the above embodiment, KrF excimer laser light (248 nm), ArF excimer laser light (193 nm), g-line (436 nm), i-line (365 nm), F ₂ Although the case where laser light (157 nm) or the like is used has been described, the present invention is not limited to this, and harmonics of a copper vapor laser, a YAG laser, a semiconductor laser, or the like can be used as illumination light for exposure.
[0206]
Further, in the exposure apparatus of the above embodiment, the projection optical system may be any of a reduction system, an equal magnification or an enlargement system, and may be any of a refraction system, a catadioptric system, and a reflection system.
[0207]
In the above embodiment, the step-and-scan type projection exposure apparatus has been described. However, the present invention is not limited to the step-and-repeat type projection exposure apparatus, and may be another type of exposure apparatus such as a proximity type exposure apparatus. Needless to say, it can be applied to
[0208]
In addition, the present invention is not limited to an exposure apparatus for manufacturing a semiconductor, but is also used for manufacturing a display including a liquid crystal display element. The exposure apparatus transfers a device pattern onto a glass plate, and a device used for manufacturing a thin-film magnetic head. The present invention can also be applied to an exposure apparatus that transfers a pattern onto a ceramic wafer, an exposure apparatus used for manufacturing an image pickup device (such as a CCD), a micromachine, an organic EL, a DNA chip, and the like. In addition, the present invention may be applied to an exposure apparatus that uses a charged particle beam such as an EUV light, an X-ray, or an electron beam and an ion beam as an exposure beam.
[0209]
In addition to micro devices such as semiconductor elements, glass substrates or silicon wafers for manufacturing reticles or masks used in light exposure equipment, EUV exposure equipment, X-ray exposure equipment, electron beam exposure equipment, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a substrate. Here, in an exposure apparatus using DUV (far ultraviolet) light or VUV (vacuum ultraviolet) light, a transmission type reticle is generally used, and as a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride, quartz, or the like is used. In a proximity type X-ray exposure apparatus, an electron beam exposure apparatus, or the like, a transmission mask (stencil mask, membrane mask) is used, and a silicon wafer or the like is used as a mask substrate.
[0210]
In the above embodiment, the case where the transport apparatus according to the present invention is applied to an exposure apparatus has been described. However, the present invention is not limited to this, and various apparatuses used in other steps of semiconductor processing, for example, The present invention can be suitably applied to an inspection apparatus, and similarly, it is possible to improve the throughput while maintaining the positioning accuracy.
[0211]
For a semiconductor device, a step of designing the function and performance of the device, a step of manufacturing a reticle based on this design step, a step of manufacturing a wafer from a silicon material, and a reticle pattern is transferred to the wafer by the exposure apparatus of the above-described embodiment. This is manufactured through a step of performing, a step of assembling a device (including a dicing step, a bonding step, and a package step), an inspection step, and the like.
[0212]
【The invention's effect】
As described above, according to the parameter adjustment method of the present invention, there is an effect that parameters for defining the operation of the device can be optimized in a short time and with high accuracy.
[0213]
Further, according to the object transport method of the present invention, there is an effect that an object can be transported accurately in a short time.
[0214]
Further, according to the exposure apparatus of the present invention, there is an effect that the throughput can be improved while maintaining the exposure accuracy.
[0215]
Further, according to the program of the present invention, there is an effect that parameters for defining the operation of the apparatus can be optimized in a short time and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an exposure apparatus according to an embodiment of the present invention.
2 (A) is a perspective view showing a wafer stage and a wafer holder, FIG. 2 (B) is a plan view showing the wafer stage and the wafer holder, and FIG. 2 (C) is a plan view showing the wafer stage and the wafer holder. FIG. 4 is a diagram (partial cross section) when the wafer holder is viewed from a −Y side.
FIG. 3 is a diagram showing a state of a wafer transfer system during pre-alignment of a wafer.
FIG. 4 is a perspective view showing a wafer transfer system and a pre-alignment system.
FIG. 5 is a diagram showing a simplified internal configuration of a measurement unit.
FIG. 6A is a diagram showing a measurement position of an 8-inch wafer by a measurement unit. FIG. 6B is a diagram showing a measurement position by a measurement unit on a wafer provided with an orientation flat.
FIG. 7 is a perspective view showing the take-in arm taken out.
FIGS. 8A to 8D are diagrams (part 1) for explaining the operation of a wafer transfer system and a wafer stage.
FIGS. 9A to 9C are diagrams (part 2) for explaining the operations of the wafer transfer system and the wafer stage.
FIGS. 10A to 10D are diagrams (part 3) for explaining the operations of the wafer transfer system and the wafer stage.
FIG. 11 is a diagram showing a position where a search alignment mark is formed on a wafer.
FIG. 12A is a diagram illustrating a speed distribution of a descending operation of a carry-in arm, and FIG. 12B is a diagram illustrating a speed distribution of a descending operation of a center table.
FIG. 13 is a flowchart showing a parameter adjustment operation of the exposure apparatus according to one embodiment of the present invention, in which a processing algorithm of a CPU in the main control device 20 is simplified.
FIG. 14 is a perspective view showing a modification of the wafer stage and the wafer holder.
[Explanation of symbols]
20: Main controller, 30: Center table, 36: Loading arm, 100: Exposure device, ALG: Alignment system, W: Wafer, W ': Wafer, WST: Wafer stage.

Claims (18)

A parameter adjustment method for adjusting the set values of a plurality of parameters that define the operation of the device,
Based on a predetermined set value for each of at least two specific parameters selected from the plurality of parameters, a plurality of combinations of the set values of the specific parameters are sequentially set in the device. A first step of obtaining information on an operation result and calculating a value of an evaluation function having a term using the obtained information on the operation result as an evaluation factor for each of the combinations;
A second step of obtaining an optimal combination of set values of the specific parameters based on the value of the evaluation function calculated for each of the combinations;
A third step of setting the optimum value included in the combination of the optimum values as the set value of each of the specific parameters in the device. Prior to the third step, the first step and the second step are repeatedly performed at least twice,
In the first step after the second time, the optimum value of each specific parameter included in the combination of the optimum values obtained in the second step up to the previous time is set as a predetermined set value in the parameter,
In the second and subsequent second steps, the optimum value obtained in the second step is compared with the value of the evaluation function corresponding to the combination of the optimum values obtained in the second step up to the previous time. When the value of the evaluation function corresponding to the combination of is small, the combination of the optimum values obtained in the second step is updated as the combination of the optimum values of the specific parameters. The parameter adjustment method according to claim 1. In the second step,
3. The parameter adjustment method according to claim 1, wherein the combination of the optimum values of the specific parameters is obtained by using at least one of a least square method and a damped least square method. When the above-mentioned damped least squares method is used,
The parameter adjustment method according to claim 3, wherein the evaluation function further includes a term obtained based on a change amount of a set value of each of the specific parameters and a predetermined damping factor. In the first step,
5. The parameter adjustment method according to claim 1, wherein at least one of a reproducibility and a range of an operation result when the device is operated a plurality of times is information on the operation result. 6. . Prior to the third step,
Assuming that the number of operations of the apparatus in the first step is a first predetermined number, the first step and the second step are performed, and a combination of optimal values of the set values of the specific parameters is obtained.
An optimum value of each of the specific parameters included in the obtained combination of the optimum values is set as a predetermined set value of each of the specific parameters, and a second predetermined number of times of operation of the device is larger than the first predetermined number of times. The parameter adjustment method according to claim 1, wherein the first step and the second step are performed as the number of times. In the first step, the sets of the specific parameters are selected in descending order of the degree of influence on the operation result of the device,
The method according to claim 1, wherein the first step, the second step, and the third step are repeatedly performed until optimal values of all parameters are set. Parameter adjustment method. The plurality of parameters include at least one of a transfer speed of an object by at least one transfer system provided in the apparatus and a position related to delivery of the object by the transfer system,
The information regarding the operation result includes at least one of positioning accuracy of the object after being transported by the transport system and transport time of the object by the transport system. 9. The parameter adjustment method according to claim 1. The plurality of parameters include a parameter that defines a detection operation of a detection system provided in the device to detect position information of the object,
The parameter adjustment method according to claim 1, wherein the information on the operation result includes positioning accuracy of the object positioned based on the position information. The parameter adjustment according to any one of claims 1 to 9, wherein in the first step, an estimated value of information on an operation result obtained by a simulation of a mathematical model of the device is used as information on the operation result. Method. A parameter adjustment method for adjusting a set value of a specific parameter that defines an operation of the device,
A first step of obtaining information on an operation result of the device when the set value of the specific parameter is sequentially set to a plurality of values;
A second step of using the information on the obtained operation result as an evaluation factor and obtaining an optimum value of the set value of the specific parameter using at least one of a least square method and an attenuated least square method;
A third step of setting the optimum value as the set value of the specific parameter in the device. An object conveying method for conveying an object,
The parameter adjustment method according to any one of claims 1 to 11, wherein a plurality of parameters that define an operation of transporting the object are to be adjusted, and information about a result of transporting the object is information about the operation result. An adjusting step to be performed;
A conveying step of conveying the object based on the parameters adjusted in the adjusting step. An object conveying method for conveying an object,
A transporting step of transporting the plurality of objects one by one by the transport system according to set values of a plurality of parameters defining a transport operation of the object by the transport system;
A detecting step of detecting information on a result of transporting an object each time a predetermined number of objects are transported by the transport system;
According to the value of the evaluation function having a term using the information on the detected transport result as an evaluation factor, a combination of optimal values of the set values of the plurality of parameters is obtained, and an optimal value included in the combination of the optimal values is obtained. An adjusting step of adjusting the plurality of parameters as respective set values of the plurality of parameters. Prior to the transporting step,
Information about each transfer result when trying to transfer the object by the transfer system by sequentially setting a plurality of combinations of the set values of the respective parameters based on a predetermined set value for each of the plurality of parameters. A table for calculating a value of an evaluation function having a term that uses information on the transport result as an evaluation factor for each of the combinations, and creating a table showing a correlation between a change in the plurality of parameters and a change in the evaluation function. Further including a creation step,
In the adjusting step, when the value of the evaluation function calculated from the information on the transport result detected in the detection step increases, the table is referred to, and the value of the evaluation function is reduced. 14. The object transport method according to claim 13, wherein a combination of set values of each parameter is selected and set. An exposure apparatus for exposing an object,
A transport system that transports the object according to a set value of at least one parameter that defines the transport operation of the object;
A stage for holding the object transferred by the transfer system;
A detection system that detects information related to a result of the transfer of the object held by the stage, which is transferred by the transfer system;
An optimum value of a set value of the at least one parameter is determined based on a value of an evaluation function having a term using information on the detected operation result as an evaluation factor, and the at least one parameter is determined based on the optimum value. And an adjusting device for adjusting the set value of the above. A program that causes a computer to execute a procedure for adjusting the set values of a plurality of parameters that define the operation of the device,
Operation of the device when a plurality of combinations of the set values of the specific parameters are sequentially set in the device with reference to predetermined set values for each of at least two specific parameters selected from the plurality of parameters. A first procedure of obtaining information on a result and calculating a value of an evaluation function having a term using the obtained information on the operation result as an evaluation factor for each of the combinations;
A second procedure of obtaining an optimal combination of set values of the specific parameters based on a value of the evaluation function calculated for each of the combinations;
And a third step of setting the optimum value included in the combination of the optimum values as the set value of each of the specific parameters in the device. To the computer,
Prior to the third procedure, the first procedure and the second procedure are repeatedly performed at least twice,
In the first procedure after the second time, the optimal value of each specific parameter included in the combination of the optimal values obtained in the second procedure up to the previous time is set as a predetermined set value of the parameter,
In the second and subsequent second procedures, the optimum value obtained in the second procedure is compared with the value of the evaluation function corresponding to the combination of the optimal values obtained in the second procedure up to the previous time. If the value of the evaluation function corresponding to the combination is small, the computer executes a procedure of updating the combination of the optimum values obtained in the second procedure this time as the combination of the optimum values of the specific parameters. The program according to claim 16, wherein the program is executed. In the second procedure,
18. The non-transitory computer-readable storage medium according to claim 16, wherein the computer is caused to execute a procedure for obtaining a combination of optimal values of the specific parameters using at least one of a least squares method and an attenuated least squares method.

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