JP3748940B2 - Positioning device, processing system, and positioning method - Google Patents

Description

【００１５】
その際に、請求項４に記載のように、正弦波近似手段が、載置台の回転中心に対する被処理体の偏心量ＥＭをＥＭ＝｜ａ｜、偏心方向ＥＤをＥＤ＝−φ＋３π／２（ａ＞０）、ＥＤ＝−φ＋π／２（ａ＜０）と設定するように構成することが好ましい。
【００１６】
また請求項５に記載のように、第１曲線近似手段が余弦波近似手段を備えた、余弦波近似手段は、Ｎ個の測定データ（θｉ，Ｙｉ）を余弦波を表す下記の式により最小２乗近似するように構成してもよい。
【００１７】
【数６】

【００１８】
その際に、請求項６に記載のように、余弦波近似手段が、載置台の回転中心に対する被処理体の偏心量ＥＭをＥＭ＝｜ａ｜、偏心方向ＥＤをＥＤ＝−φ＋π（ａ＞０）、ＥＤ＝−φ（ａ＜０）と設定するように構成することが好ましい。
【００１９】
また、請求項７に記載のように、上記位置決め装置に、載置台を回転駆動するための第１駆動手段と、載置台上から被処理体を受け取るための旋回および伸縮可能な搬送アームと、搬送アームを旋回および伸縮駆動するための第２駆動手段と、偏心方向および偏心量に基づいて、第１および第２駆動手段を介して、載置台および搬送アームの動作を制御する制御手段とをさらに設けてもよい。
【００２０】
また、請求項８に記載のように、上記位置決め装置に、第１周縁形状信号と第３周縁形状信号に基づいて、第２周縁形状信号のピーク部分に対応する互いに１８０度分ずれた第１周縁形状信号の２つの候補部分のいずれか一方を、切欠き部に対応する部分として選択する第２選択手段と、第２選択手段により選択された部分に相当する第１周縁形状信号を曲線近似して第４周縁形状信号を得る第２曲線近似手段と、第４周縁形状信号に基づいて、載置台の回転中心から切欠き部の方向を求める第３演算手段とをさらに備えるように構成してもよい。
【００２１】
さらに、請求項９に記載のように、第２選択手段を、第１周縁形状信号と第３周縁形状信号との差分をとり、２つの候補部分の差分データの平均値を比較し、一方の候補部分が前記切欠き部に対応すると判断するように構成することができる。
【００２２】
さらに、請求項１０に記載のように、第２曲線近似手段を、Ｎ個の測定データ（θｉ，Ｙｉ）を下記の２次式により最小２乗近似するものとして構成することができる。
【００２３】
【数７】

【００２４】
さらに、請求項１１に記載のように、第３演算手段を、前記２次式から角度βを求めるものとして構成することができる。ここで、前記角度βは前記載置台の回転中心を通る前記検出手段の光軸と、前記回転中心と前記切欠き部の最近接部とを結ぶ直線とがなす角度を表すものである。
【００２５】
【数８】

【００２６】
さらに請求項１２に記載のように、上記装置に、載置台を回転駆動するための第１駆動手段と、載置台上から被処理体を受け取るための旋回および伸縮可能な搬送アームと、搬送アームを旋回および伸縮駆動するための第２駆動手段と、偏心方向、偏心量および切欠き部の方向に基づいて、第１および第２駆動手段を介して、載置台および搬送アームの動作を制御する制御手段とを設けるように構成してもよい。
【００２７】
さらに請求項１３に記載のように、搬送アームがその旋回の中心となる固定軸を有し、搬送アームにより被処理体を受け取る際に、被処理体の中心と切欠き部の中心とを結ぶ直線の延長線上に固定軸がくるように、載置台が回転して被処理体が位置決めされるように構成してもよい。
【００２８】
さらに本発明の別の観点に基づいて構成される、輪郭が円形で且つ外縁部に位置決め用切欠き部を有する被処理体を位置決めするための位置決め装置は、請求項１４に記載のように、被処理体を支持すると共に回転可能な載置台と、載置台上の被処理体の外縁形状を光学的に検出する検出手段と、検出手段から出力された被処理体の３６０度回転分の第１周縁形状信号を１８０度分ずらして重ね合わせ第２周縁形状信号を得る演算手段と、第２周縁形状信号からピーク部分を抽出すると共に、ピーク部分に対応する互いに１８０度分ずれた第１周縁形状信号の２つの候補部分を切欠き部に対応する部分として検索する候補検索手段と、２つの候補部分の信号を評価し２つの候補部分のいずれか一方を切欠き部に対応する部分として選択する評価および選択手段とを備えたことを特徴としている。
【００２９】
また請求項１５に記載のように、上記位置決め装置の評価および選択手段を、前記２つの候補部分のそれぞれに対して凸形状の評価用パターンを積和演算し、且つ互いの積和値の平均値を比較するように構成してもよい。
【００３０】
また請求項１６に記載のように、上記装置に、載置台を回転駆動するための第１駆動手段と、載置台上から被処理体を受け取るための旋回および伸縮可能な搬送アームと、搬送アームを旋回および伸縮駆動するための第２駆動手段と、評価および選択手段からの信号に基づいて、第１および第２駆動手段を介して、載置台および搬送アームの動作を制御する制御手段とをさらに設けてもよい。
【００３１】
さらに本発明の別の観点によれば、輪郭が円形で且つ外縁部に位置決め用切欠き部を有する被処理体を処理するための処理システムは、請求項１７に記載のように、被処理体を収納し且つ処理を施すための複数の処理室と、処理室外で被処理体を支持するための回転可能な載置台と、載置台を回転駆動するための第１駆動手段と、処理室と載置台との間で被処理体を搬送するための搬送アームと、伸縮アームを旋回および伸縮駆動するための第２駆動手段と、載置台上の被処理体の外縁形状を光学的に検出する検出手段と、検出手段から出力された被処理体の３６０度回転分の第１周縁形状信号を１８０度分ずらして重ね合わせ第２周縁形状信号を得る第１演算手段と、第２周縁形状信号からピーク部分を抽出するピーク抽出手段と、第１周縁形状信号のピーク部分を含む所定範囲およびその範囲に対して１８０度分ずれた範囲を無効データとする無効化手段と、第１周縁形状信号から無効データを除いた有効データに基づいて第１周縁形状信号を曲線近似して第３周縁形状信号を得る第１曲線近似手段と、第３周縁形状信号に基づいて載置台の回転中心に対する被処理体の偏心方向および偏心量を求める第２演算手段と、偏心方向および偏心量に基づいて、第１および第２駆動手段を介して、載置台および伸縮アームの動作を制御する制御手段と、
を備えたことを特徴としている。
【００３２】
さらに請求項１８に記載のように、上記装置に、第１周縁形状信号と第３周縁形状信号に基づいて、第２周縁形状信号のピーク部分に対応する互いに１８０度分ずれた第１周縁形状信号の２つの候補部分のいずれか一方を、切欠き部に対応する部分として選択する第２選択手段と、第２選択手段により選択された部分に相当する第１周縁形状信号を曲線近似して第４周縁形状信号を得る第２曲線近似手段と、第４周縁形状信号に基づいて、載置台の回転中心からの切欠き部の方向を求める第３演算手段とをさらに設け、制御手段により、偏心方向、偏心量および切欠き部の方向に基づいて、第１および第２駆動手段を介して、載置台および伸縮アームの動作を制御するように構成してもよい。
【００３３】
さらに請求項１９に記載のように、搬送アームがその旋回の中心となる固定軸を有し、その搬送アームにより被処理体を受け取る際に、被処理体の中心と切欠き部の中心を結ぶ直線の延長線上に固定軸がくるように、載置台が回転して被処理体が位置決めされることが好ましい。
【００３４】
さらに本発明の別の観点によれば、輪郭が円形で且つ外縁部に位置決め用切欠き部を有する被処理体を処理するための処理システムは、被処理体を収納し且つ処理を施すための複数の処理室と、処理室外で被処理体を支持するための回転可能な載置台と、載置台を回転駆動するための第１駆動手段と、処理室と載置台との間で被処理体を搬送するための搬送アームと、伸縮アームを旋回および伸縮駆動するための第２駆動手段と、載置台上の被処理体の外縁形状を光学的に検出する検出手段と、検出手段から出力された被処理体の３６０度回転分の第１周縁形状信号を１８０度分ずらして重ね合わせ第２周縁形状信号を得る第１演算手段と、第２周縁形状信号からピーク部分を抽出すると共に、ピーク部分に対応する互いに１８０度分ずれた第１周縁形状信号の２つの候補部分を切欠き部に対応する部分として検索する候補検索手段と、２つの候補部分の信号を評価し、２つの候補部分のいずれか一方を、切欠き部に対応する部分として選択する評価および選択手段と、評価および選択手段からの信号に基づいて、第１および第２駆動手段を介して、載置台および搬送アームの動作を制御する制御手段とを備えたことを特徴としている。
【００３５】
さらに本発明の別の観点によれば，支配的な輪郭が実質的に円形で且つ外縁部に位置決め用切欠き部を有する被処理体を位置決めするための位置決め方法が提供される。
上記のように構成された本発明にかかる位置決め装置，処理システムおよび位置決め方法は，以下に説明するように動作する。
【００３６】
まず、本発明にかかる位置決め装置では、検出手段によりウェハなどの被処理体の外縁形状に関する情報が光学的に検出される。その際に、検出手段を発光素子と受光素子とから構成すれば簡便な装置を構成できる。また、その検出手段としてＣＣＤ撮像素子を用いれば、より加工しやすいデータが得られるので、処理の高速化を図れる。
【００３７】
ここで、ウェハの中心と回転載置台の回転中心とが完全に一致している場合には、一回転（３６０度）の間、同一位置において光学信号が検出されるので、ウェハの外縁形状の位置座標は、図１９に示すように、水平方向への直線Ａとしてプロットされる。なお直線Ａに乗っているの凸部（ピーク部分）Ｂは、切欠マークであり、他の部分に比較して、より多くの光を透過したことを示している。
【００３８】
しかしながら、実際には、ウェハの中心と回転載置台の回転中心とは偏心しているので、図２０に示すように、ウェハの外縁形状の位置座標は、曲線Ｃとしてプロットされる。なお曲線Ｃ上の凸部（ピーク部分）Ｄは、図１９に示す凸部（ピーク部分）Ｂと同様に、切欠マークに対応する部分であり、他の部分に比較して、より多くの光を透過したことを示している。
【００３９】
ところで、被処理体の外縁形状の位置座標は、回転載置台上で回転されるので、３６０゜周期を有している。同時に、回転載置台上で回転される被処理体の形状が、ウェハのような円形形状のように線対象である場合には、被処理体の外縁形状の位置座標の位相の符号は、１８０度周期で反転し、切欠マークなどを除けば、１８０度周期で略相似形を示すことになる。
【００４０】
そこで、本発明の第１の観点にかかる位置決め装置では、第１演算手段により、被処理体の１回転（３６０度）分の外縁形状の位置座標を示す第１周縁形状信号を半周期（１８０度）分ずらして重ね合わせることにより、図２１に示すような、回転載置台の回転中心とウェハの中心との偏心分が相殺された第２外縁形状信号Ｅ、Ｆを得ることができる。
【００４１】
次いで、上記第２外縁形状信号の周縁形状Ｅ、Ｆからピーク部分が抽出される。このピーク部分は、上述したように、切欠マークの存在により光が余分に透過したことにより形成されたものである。この点、第１周縁形状信号では、図２０に示すように、ピーク部分Ｄが曲線Ｃ上に乗っているため、検出に時間を要していた。しかし、本装置によれば、第２周縁形状信号において、ウェハの中心と回転載置台の回転中心との偏心分が相殺されているので、ピーク部分の検出を容易に行うことができる。
【００４２】
そして、第２周縁形状信号のピーク部分か又はそのピーク部分と半周期（１８０度）分ずれた部分に、切欠マーク、すなわち位置決め用切欠き部が存在すると考えられるので、第２の視点の装置では、選択手段により上記部分のうちいずれか一方を切欠マークとして選択することができる。
【００４３】
その際に、第１周縁形状信号中の切欠マークが存在すると考えられる部分、すなわち第２周縁形状信号から検出されたピーク部分又はそのピーク部分と半周期（１８０度）分ずれた部分のそれぞれに対して、例えば図１８に示すような、予め設定された評価用パターンを積和演算することにより、切欠マークとそうでない部分との差異を際だたせることができる。その結果、切欠マークを容易に選択することができる。
【００４４】
さらに、本装置によれば、回転載置台の回転中心に対する被処理体の中心の偏心量および偏心方向を求めるために所定の前処理が行われる。すなわち、切欠マークにより形成されたピーク部分は、被処理体の周縁形状を曲線近似し、その近似曲線から偏心量および偏心方向を決定するためには、不要なデータである。そこで、本発明によれば、ピーク抽出手段により第２周縁形状信号から求めたピーク部分を含む所定範囲とその範囲から半周期（１８０度）分ずれた範囲に相当する第１周縁形状信号のデータを、データ無効化手段により無効データとして処理する。
【００４５】
その際に、本装置では、いちいち切欠マークの位置を特定せず、切欠マークが存在する可能性のある候補範囲を全て無効データ化するので、データ処理時間を短縮することができる。また、無効化されたデータ部分を補完することにより、より精度の高い位置決めを高速に行うことができる。
【００４６】
さらに、本装置では、第１曲線近似手段により、第４の装置により無効データを除いた第１周縁形状信号のデータを曲線近似して第３周縁形状信号を求める。このように第１周縁形状信号のデータを曲線近似することにより、被処理体の周縁形状を数学的に処理することが可能となり、処理の高速化を図れる。
【００４７】
なお、曲線近似に際しては、正弦波近似手段により正弦波近似することにより処理の簡略化および高速化が図れ、特に正弦波を最小２乗近似することにより、従来のように、有効データの中から特定データを選択する前処理（例えば、代表点を３点選択する処理）が不要になる。
【００４８】
さらに、本装置では、第２演算手段により、曲線近似された周縁形状信号のピーク部分（すなわち、偏心方向および偏心量を示す部分）に基づいて、被処理体の中心と回転載置台の回転中心との偏心方向および偏心量を、数学的に処理することができるので、処理の高速化を図れる。
【００４９】
さらに、本装置では、第２選択手段により、ウェハの偏心量および偏心方向を求めるために使用した第１、第２および第３周縁形状信号に基づいて、ウェハの切欠マークの位置を容易に決定することができる。なお、第２選択手段として、差分器と比較器を有する装置を用いることにより、装置の簡略化および処理の高速化が図れる。
【００５０】
さらに、切欠マークの候補位置のデータを第２曲線近似手段、例えば最小２乗近似手段により２次曲線に近似した後、第３演算手段により、切欠マークの位置、例えば切欠マークの中心位置を求めることができる。
【００５１】
このようにウェハの切欠マークの位置を決定する場合に、従来の装置では、ウェハの偏心量のアライメントを行った後、改めて切欠マークの位置を決定し、アライメントを行っていたため、位置決めに２ステップが必要であった。この点、本発明によれば、ウェハの偏心量および偏心方向を求めるために使用したものと同じ信号に基づいて、ウェハの切欠マークの位置をも求めることができるために、１ステップでウェハの位置決めを行うことが可能となり、処理の高速化が図れる。
【００５２】
特に本発明は、ウェハを移載する動作の頻度が高く、従って、位置決め頻度も高く、またそれらの処理の高速化要求されるマルチチャンバ方式の処理装置において、優れた効果を奏することができる。
【００５３】
さらに、本発明によれば、ウェハの中心と切欠マーク中心を結ぶ直線の延長線上に搬送アームの固定軸を持ってくるように位置決めを行うことにより、従来の装置のように、ウェハの偏心量および偏心方向のアライメントとウェハの切欠マークのアライメントとを２ステップで行わなくとも、本発明により偏心量および偏心方向、並びに切欠マークの位置が求められたウェハを搬送アームに対して１回の操作により受け渡しができる。
【００５４】
【発明の実施の形態】
以下に添付図面を参照しながら、本発明にかかる位置決め装置および処理システムの好適な実施の形態について詳細に説明する。
【００５５】
まず、本発明の実施例に係る位置決め装置を有し、且つ２以上の真空処理室を備えたマルチチャンバ方式の処理システムを、図１を参照して説明する。
【００５６】
図示のように、真空処理システムは、共通移載室（第１移載室）２を中心として、第１〜第４の４つの真空処理室４Ａ、４Ｂ、４Ｃ、４Ｄと、第１および第２の予備真空室６Ａ、６Ｂと、第１および第２のカセット室８Ａ、８Ｂが接続されて、いわゆるクラスタ状に処理室が配置されたマルチチャンバ方式の処理装置１０を構成している。
【００５７】
そして、これらの処理室は共通のサブクリーンルーム１２内に収容されて、大気から隔離されている。さらに、サブクリーンルーム１２に隣接して第２移載室１４が接続されて、外部と処理システム１０との間で被処理体の受け渡しを行うように構成されている。
【００５８】
第１〜第４の４つの真空処理室４Ａ、４Ｂ、４Ｃ、４Ｄは、被処理体である半導体ウェハ表面に所定の処理を連続して施すための装置の集合体である。例えば、ウェハのシリコン上に形成されたシリコン層間絶縁層にスルーホールを形成し、そのスルーホールに対してチタン膜／窒化チタン膜／タングステン膜を配線材として成膜するための処理システムを例に挙げれば、次のような構成とすることができる。
・第１の真空処理室４Ａとして、酸化シリコンから成る層間絶縁層にスルーホールをエッチングするプラズマエッチング装置。
・第２の真空処理室４Ｂとして、上記スルーホールに対してオーミックコンタクト層としてチタン層を形成するとともに、そのチタン層の上にバリヤ層として窒化チタン層を形成するためのスパッタ装置。
・第３の真空処理室４Ｃとして、上記バリヤ層の上にタングステン層を形成するためのＣＶＤ装置。
・第４の真空処理室４Ｄとして、スルーホールに形成されたタングステン層をエッチングバックするためのプラズマエッチング装置。
【００５９】
なお、以上示した装置群は、ほんの一例に過ぎず、要求される処理に応じて、様々な種類および数量の処理室を組み合わせてマルチチャンバ方式の処理システム１０を構成できることは言うまでもない。
【００６０】
ここで、上記処理システムの全体構成について説明する。まず第２移載室１４と外部とはドアＧ１を介して連通されている。第２移載室１４内には、例えば、第１〜第４の４つのカセット載置台１６Ａ、１６Ｂ、１６Ｃ、１６Ｄが横並びに設置されている。なお、図示の例では、第１および第３のカセット載置台１６Ａおよび１６ＣにカセットＣ１、Ｃ２が載置されている。これらカセットＣ１、Ｃ２は、所定枚数、例えば２４枚のウェハＷを収容して、移載するためのものである。
【００６１】
さらに、第２移載室１４内には、カセット搬送装置１８が設置されている。カセット搬送装置は、第１〜第４のカセット載置台１６Ａ〜１６Ｄの列に対して平行に（図示の例で、矢印方向に）移動可能であり、搬送アーム１８Ａにより、未処理のウェハが収容された所望のカセットを取り出し、カセット室８Ａ、８Ｂに移載するとともに、処理済みのウェハが収容されたカセットをカセット室８Ａ、８Ｂから回収できる。
【００６２】
上記第２移載室１４は、上記第１カセット室８ＡとはドアバルブＧ２を介して、第２カセット室８ＢとはドアバルブＧ３を介して、それぞれ接続されている。第１および第２カセット室８Ａ、８Ｂにはそれぞれ昇降自在のカセットステージ（図示せず）が設けられている。また第１および第２カセット室８Ａ、８Ｂと共通移載室２とは、ゲートバルブＧ４、Ｇ５を介して接続されている。
【００６３】
なお、第１および第２カセット室８Ａ、８Ｂは、それぞれ気密に構成されるとともに、図示しない排気経路および給気経路を有しており、その内部を所望の圧力雰囲気に調整可能である。従って、ドアバルブＧ２、Ｇ３を開放する場合（ゲートバルブＧ４、Ｇ５は閉止）には、第２移載室１４と第１および第２カセット室８Ａ、８Ｂ間を略同一の圧力雰囲気とすることができる。逆にゲートバルブＧ４，Ｇ５を開放する場合（ドアバルブＧ２、Ｇ３は閉止）には、共通移載室２と第１および第２カセット室８Ａ、８Ｂ間を略同一の圧力雰囲気とすることができる。
【００６４】
さて、上記共通移載室（第１移載室）２は、略円形の平面を有する気密室から成り、上述のように、ゲートバルブＧ４、Ｇ５を介して第１および第２カセット室８Ａ、８Ｂと接続されるとともに、ゲートバルブＧ６、Ｇ７、Ｇ８、Ｇ９を介して第１〜第４の真空処理室４Ａ〜４Ｄに接続されている。これらの真空処理室４Ａ〜４Ｄは、例えば、上述のようなエッチング装置、スパッタ装置、ＣＶＤ装置であり、各室内に収容された載置台２０Ａ、２０Ｂ、２０Ｃ、２０Ｄにウェハを載置固定して、所定の処理を施すものであるが、それらの構造の詳細な説明はここでは省略する。
【００６５】
さらに、上記共通移載室（第１移載室）２は、連通路２２Ａ、２２Ｂを介して第１および第２予備真空室６Ａ、６Ｂに接続されている。第１および第２予備真空室６Ａ、６Ｂには、載置台２４Ａ、２４Ｂが収容されている。これらの載置台２４Ａ、２４Ｂには、載置されたウェハを加熱するための加熱手段と、載置されたウェハを冷却するための冷却手段が実装されており、必要に応じてウェハを加熱又は冷却することが可能なように構成されている。
【００６６】
さらに上記共通移載室２内には、搬送アーム２６を備えた移載手段２８がほぼ中央に設置されている。この搬送アーム２６は、例えば多関節アームから成るものであり、共通移載室２の周囲に配置された、第１〜第４の真空処理室４Ａ〜４Ｄ、第１および第２の予備真空室２４Ａ、２４Ｂ、第１および第２のカセット室８Ａ、８Ｂの間で、所定のウェハを移載することができるように構成されている。
【００６７】
また、上記移載室２の第１および第２カセット室８Ａ、８Ｂ側には、被処理体であるウェハの位置合わせをするための位置決め装置３０が配置されている。この位置決め装置３０は、回転載置台ユニット３２と光学式の検出手段３４とから主に構成されているが、その詳細については後述する。
【００６８】
そして、第１〜第４の真空処理室４Ａ〜４Ｂ、および共通移載室２についても、上述の第１および第２カセット室８Ａ、８Ｂと同様に、図示しない排気経路と給気経路がそれぞれ設置されている。従って、必要に応じて、所定のゲートバルブを開閉した後、給気経路を介して所定の処理ガスやパージガスを各室内に導入したり、あるいは排気経路を介して各室を所定の圧力雰囲気に個別に制御することが可能である。
【００６９】
以上のように、本発明実施例に係る位置決め装置を有するマルチチャンバ方式の真空処理システム１０は構成されている。さて、上記のように構成されたマルチチャンバ方式の処理システム１０において、ウェハを所定の処理室に対して高い精度で搬入搬出するためには、搬送アーム２６によりウェハＷを高い精度で受け取る必要がある。そのために、通常は、搬送アーム２６により移載するウェハＷの中心と切欠マークとを、一旦本発明に係る位置決め装置３０により位置合わせし、その後、再び搬送アーム２６によりウェハＷを受け取り、所定の処理室に移載するように構成されている。
【００７０】
次に、かかる位置決め装置３０の構成について図４を参照しながら説明する。図示の位置決め装置３０は、回転載置台ユニット３２と検出手段３４とから主に構成されている。
【００７１】
回転載置台ユニット３２は、駆動部３６と、その駆動部３６にベローズ３８を介して設置された回転駆動軸４０と、その回転駆動軸４０上に固定された円板状回転載置台４２とから構成されている。従って、回転載置台４２は、ベローズ３８により昇降自在であるとともに、駆動部３６より回転駆動軸４０を介して伝達された動力により所定量だけ回転させることができる。なお、回転載置台４２の外径は、ウェハＷの外径よりも小さく構成されるが、回転時にウェハＷを十分に支承できる大きさであることが好ましい。また回転載置台４２の上面には図示しないゴムパッドまたは静電吸着パッドが設置されており、回転時にウェハＷを遠心力に抗して固定することが可能である。
【００７２】
検出手段３４は、図示の例では、発光部と受光部とにより構成されている。発光部は発光ダイオードなどの発光素子４４から成る。発光素子４４から射出された光は、レンズ４６、下方ミラー４８、上方ミラー５０を介して、受光素子５２により受光され、位置信号に変換された後、バス５４、５６を介して制御部５８に送られる。制御部５８に送られた信号は、制御部５８の各信号処理手段により所定の処理が施されて、ウェハの偏心量および偏心方向、並びに切欠マークの方向が求められる。かかる信号処理については、後で詳述する。制御部５８は、上記偏心量および偏心方向、並びに切欠きアーム等の情報に基づき、それぞれの駆動部２９および駆動部３６を介して、搬送アーム２６および回転載置台４２の動作を制御し、ウェハのアライメントを行う。
【００７３】
なお、図示の例では、検出手段３４を発光素子４４と受光素子５２とから構成したが、本発明はかかる例に限定されない。例えば、ＣＣＤカメラにより直接ウェハの周縁部を撮像し、画像データとして処理することも可能であることは言うまでもない。このように、ＣＣＤカメラを用いた場合には、より加工しやすい信号データを得ることができるので、処理の高速化が図れる。
【００７４】
本発明に係る位置決め装置３０は上記のように構成されているので、図４〜図６に示すように動作する。すなわち、図４に示すように、回転載置台４２を下方位置に下げた状態で、搬送アーム２６によりウェハＷを回転載置台４２の上方に搬送する。次いで、図５に示すように、回転載置台４２を上昇させ、搬送アーム２６よりウェハＷを回転載置台４２上に受け渡した後に、搬送アーム２６を引っ込める。そして、図示しないゴムパッドまたは静電吸着パッドによりウェハＷを回転載置台４２上に固定することにより位置決め処理の準備が完了する。
【００７５】
次いで、図６に示すように、回転載置台４２をさらに上昇させるとともに、ウェハＷとともに回転載置台４２を回転させる。さらに、発光素子４４より光を照射し、レンズ４６、ミラー４８、５０を介して受光素子５２により受光する。その際に、回転するウェハＷの周縁が、光路を横切るように、ウェハＷが回転載置台４２上に載置される。従って、ウェハＷが１回転する間に、ウェハＷの周縁を透過する光（すなわち、ウェハＷの周縁により遮られなかった光）を検出することにより、ウェハＷの周縁形状に関する情報を収集することができる。
【００７６】
ここで、ウェハＷの中心と回転載置台４２の回転中心が一致していれば、略円形のウェハの周縁形状は一定であり、検出された信号は、図１９の実線Ａに示すように、光を透過する切欠マークに対応する部分Ｂを除き、ほぼ水平の直線としてプロットされる。そして、ウェハＷの位置決めに際しては、切欠マークに対応する部分Ｂの位置を決定すれば十分である。
【００７７】
しかしながら、実際には、図２および図３に示すように、ウェハＷの中心ＯＷと回転載置台４２の回転中心ＯＰとは偏心しており、検出された信号Ｃは、図２０の実線Ｃに示すように、光を透過する切欠マークに対応する部分Ｄを除き、略正弦波の曲線としてプロットされる。従って、ウェハＷの位置決めに際しては、ウェハＷの切欠マークに対応する部分Ｄの位置を検出するのみならず、回転載置台４２の回転中心ＯＰに対するウェハＷの中心ＯＷの偏心量および偏心方向を求める必要がある。
【００７８】
そのために、本発明に係る位置決め装置３０では、制御部５８を以下に示すような信号処理手段から構成している。次に、図７〜図９を参照しながら、上記制御部５８を構成する信号処理手段の一実施例について説明する。なお、図７〜図９図において、各信号処理手段の下に示したグラフは、各信号処理手段において実行される信号処理の概略を示したものである。
【００７９】
図７に示すように、検出手段３４により光学的に検出されたウェハＷの外縁形状は第１周縁形状信号６０（６０Ａ、６０Ｂ）として、第１演算手段６２に送られる。この第１演算手段６２は、回転載置台４２に載置されたウェハＷの１回転（３６０度）分の第１周縁形状信号６０（６０Ａ、６０Ｂ）を半周期（１８０度）分ずらして重ね合わせて、第２周縁形状信号６４を得るためのものである。そして、この第２周縁形状信号６４においては、図示のように、半周期（１８０度）分ずれた曲線部分同士が互いに相殺され（すなわち、ウェハＷの中心の回転載置台４２の中心に対する偏心分が相殺され）、光を透過した切欠マーク部に相当するピーク部分６６のみが顕著に表される。
【００８０】
この第２周縁形状信号６４を出力する第１演算手段６２の後段には、ピーク抽出手段６８が接続されている。このピーク抽出手段６８は、第２周縁形状信号６４において顕著になったピーク部分６６を抽出するためのものである。なお、このピーク抽出手段６８では、半周期分に重ねられた信号のみを処理対象としているので、抽出されたピーク部分はあくまでも切欠マークの候補位置であり、実際の切欠マークは、抽出されたピーク部分又はその部分から半周期ずれた部分に存在することに留意する必要がある。
【００８１】
さらにピーク抽出手段６８の後段には、データ無効化手段７０が接続されている。後述する曲線近似処理において、切欠マーク部に現れるピーク信号部分は不要なデータなので、このデータ無効化手段６８により切欠マーク部の信号を無効データとして予め処理するのである。その際に、データ無効化手段６８は、ピーク抽出手段６８により抽出されたピーク部分から推定される切欠マーク候補部分（すなわち、ピーク部分７２とその部分から半周期ずれた部分７４）を全て無効化する。このように、切欠マーク候補部分から実際の切欠マークに対応する部分を選択する処理手順を省略することにより、処理の高速化が図れるのである。
【００８２】
なお、説明を簡略化するため図示は省略したが、このデータ無効化手段６８の後段に、無効化されたデータ部分を残余の有効データに基づいて補完し、有効データ化するデータ補完手段を設けることも可能である。
【００８３】
さらにデータ無効化手段７０の後段には、図８に示すような第１曲線近似手段７６が接続されている。この第１曲線近似手段７６は、第１周縁形状信号６０から無効データを除いた有効データに基づいて、第１周縁形状信号６０を曲線近似して第３周縁形状信号７８を得るものである。この第１曲線近似手段７６としては、第１周縁形状信号６０を正弦波近似する手段であることが好ましい、特に、第１周縁形状信号６０の有効データ群から直接正弦波近似を行うことが可能な最小２乗近似法を用いることが好ましい。
【００８４】
さらに第１曲線近似手段７６の後段には第２演算手段８０が接続されている。この第２演算手段８０は、第１曲線近似手段７６により曲線近似された第３周縁形状信号７８より、ウェハＷの中心の回転載置台４２の回転中心に対する偏心量ＥM、および偏心方向ＥDを求めるものである。以上のように、本発明に係る位置決め装置３２によれば、従来のように、ウェハＷの偏心量および偏心方向を求めるに際して、有効データの中から特定データを選択する前処理（例えば、代表点３点を選択する処理）が不要となり、有効データ群から直接ウェハＷの偏心量および偏心方向を求めることができる。
【００８５】
さらに第２演算手段８０の後段には第２選択手段８２が接続されている。上述のように、第２周縁形状信号６４より切欠マークが存在する候補部分（２カ所）が明らかになっているが、切欠マークの位置を確定するにあたっては、切欠マーク候補部分から実際に切欠マークが存在している部分を確定する必要がある。そして、実際に切欠マークが存在する部分は、この第２選択手段８２により決定される。切欠マークに対応する部分を確定するにあたっては、まず、例えば実線８４で示すように第１周縁形状信号６０と第３周縁形状信号７８の差分をとる。次いで、その差分データ８４中の切欠マーク候補部分８６Ａ、８６Ｂの平均値同士を比較し、平均値の高い部分（図示の例では、８６Ａ）に切欠マークが存在すると判断することができる。
【００８６】
さらに第２選択手段８２の後段には、図９に示すように第２曲線近似手段８８が接続されている。この第２曲線近似手段８８は、第２選択手段８２により選択された切欠マーク部分に相当する第１周縁形状信号６０を曲線近似して第４周縁形状信号９０を求めるためのものである。そして、この第４周縁形状信号９０を求めるに際しても、最小２乗近似法により、有効データ群の中から直接２次曲線として曲線近似することが好ましい。なおかかる処理の詳細については後述する。
【００８７】
さらに第２曲線近似手段８８の後段には第３演算手段９２が接続されている。この第３演算手段９２は第２曲線近似手段８８により求められた第４周縁形状信号９０のピーク値に基づいて直接回転載置台４２の回転中心に対する切欠マークの最近接部Ｎｃ或いはＦｃを求めるためのものである。
【００８８】
以上のようにして、本発明に係る位置決め装置によれば、一連の信号処理により、ウェハＷの中心の回転載置台４２の中心に対する偏心量および偏心方向と、ウェハＷの切欠マークの位置とを同時に求めることが可能である。
【００８９】
従って、従来の装置のように、ウェハＷの中心の位置合わせと、ウェハＷの切欠マークの位置合わせとを２ステップで行う必要が無くなり、１ステップで処理することができるので、ウェハＷの位置決め処理を高速化できる。
【００９０】
また、その際に、従来の装置のように、検出手段によりサンプリングされた有効データ群の中から代表点を選択せずに、有効データ群を直接処理して、ウェハＷの偏心量および偏心方向、ウェハＷの切欠マークの位置を求めることができるので、さらに処理の高速化を図れる。
【００９１】
次に、本発明に係る位置決め装置によるウェハＷの中心および切欠マークの位置決め処理のアルゴリズムの一実施例について、図１０〜図１３を参照しながら説明する。
【００９２】
１．前処理、および切欠マーク候補位置の検索
まず、図１０に示すように、ステップＳ１０１において、検出手段３４によりサンプリングされたウェハＷの周縁形状を示すデータからノイズの除去が行われる。このノイズの除去は、例えば近傍の５つのサンプリングポイントの平均値をとり、ある場所のデータがその前後の平均値よりも所定値以上突出している場合には、その部分にノイズが含まれていると判断し、無効データ化することにより行われる。
【００９３】
次いでステップＳ１０２に進み、有効データの判定が行われる。図４に示すように、一般に光学式の検出手段３４では、ある幅を有する光線（図中、点線で示す）により、ウェハＷの周縁形状を測定している。従って、ウェハＷの回転載置台４２に対する偏心量が大きく、ウェハＷの周縁の軌道が、その光線の最大幅（Ｍａｘ）と最小幅（Ｍｉｎ）を超える場合には、図１０の（ａ）に点線で示す部分１０５ａ、１０５ｂ、１０５ｃに関して有効なサンプリングが行えない。そこで、ステップＳ１０２において、上記部分のデータを無効化する前処理が行われる。
【００９４】
次いでステップＳ１０３において、第１演算手段６２により、検出手段３４によりサンプリングされた第１周縁形状信号６０を半周期（１８０度）分ずらして重ね合わせて第２周縁形状６４を得るとともに、ピーク抽出手段６８により第２周縁形状６４のピーク部分６６を抽出する（図１０（ｂ））。
【００９５】
次いでステップＳ１０４に進み、有効データの割合を判定する。例えば、有効データが１回転（３６０度）分のサンプリングデータの３／１０に満たない場合（すなわち、図１０（ｃ）に示すように、重ね合わされた半回転（１８０度）分のサンプリングデータの３／５に満たない場合）には、有効なアライメント処理が行えない旨のエラー信号を出力し、ウェハＷを搬送アーム２６により回転載置台４２に載せ直す指令を送ることができる。
【００９６】
なお、有効データの判定の基準は上記実施例に限定されないことは言うまでもなく、要求精度に応じて任意の数値に設定することが可能である。
【００９７】
また、この実施例では、第１演算手段６２により第２周縁形状信号６４を求めた後に、サンプリングデータのエラーを判断しているが、ステップＳ１０２により有効データ判定する際に一括して、適当な基準値に基づいてサンプリングデータのエラーを判断する構成を採用することもできる。
【００９８】
次いで、図１１に示すステップＳ１１１に進み、ステップＳ１０３において重ね合わされたデータの平均値と標準偏差が演算される。その際には、ステップＳ１０３において検出されたピーク値（最大値）の位置から±３６度の範囲を除く有効データ（図１１（ａ）において、丸で囲った部分）が対象とされる。例えば、図２に示すようなオリエンテーションフラットを切欠マークとして使用する場合に、通常はオリエンテーションフラットはウェハＷの全周の３６度の範囲に収まるように設計されるので、最大の誤差を見ても、切欠マークは上記ピーク値６６から±３６度の範囲に存在すると考えられ、その部分を除く有効データを対象とすることにより、高い精度の平均値と標準偏差を得ることができるからである。
【００９９】
次いで、ステップＳ１１２に進み、切欠マーク候補位置の検索が行われる。その際には、例えば、重ね合わせデータの平均値（Ａｖｅ．）＋４σをしきい値として、そのしきい値を超える部分に切欠マーク候補が存在するものと判断することが可能である。なお、ここで切欠マーク位置と言わずに、切欠マーク候補位置と称しているのは、ステップＳ１１２での処理の対象は半回転分の重ね合わせデータであり、従って、実際の切欠マークは、当該処理により切欠マークがあると判定された部分か、あるいはその部分から半回転（１８０度）分ずれた部分に存在するものと考えられるからである。
【０１００】
次いで、処理はステップＳ１１３に進み、切欠マーク候補部分に存在するデータの数が３未満であるかどうかが判断される。すなわち、後続の処理において、切欠マーク部分に含まれるサンプリングデータに基づいて２次式による放物線近似が行われるが、２次式による放物線近似を行うためには、少なくとも３点に関するデータが必要だからである。従って、切欠マーク候補部分に存在するデータ３未満である場合には、切欠マーク部の特定を行うことが困難であるので、エラーの信号が出力される。
【０１０１】
２．ウェハＷの偏心量および偏心方向の計算
以上のような前処理を終了した後、アルゴリズムは、図１２に示すような、ウェハＷの偏心量および偏心方向の計算処理に進む。偏心量および偏心方向を求める場合に、本発明に係る位置決め装置３２においては、後述するように、第１曲線近似手段７６により第１周縁形状信号６０の正弦波近似が行われるが、その際に、切欠マーク部のデータは曲線近似の精度を落とす原因となるため、予め除去する必要がある。
【０１０２】
そこで、ステップＳ１２１において、データ無効化手段７０により、切欠マーク候補部分（図１２（ａ）の７２、７４）に含まれるデータを無効化する。なお以上の処理において無効化されたサンプリングデータ部分は、次の通りである。・ステップＳ１０１によりノイズと判定された部分
・ステップＳ１０２により検出手段３４の検出限界を超えたと判定された部分
・ステップＳ１１２により切欠マーク候補位置と判定された部分、およびその部分から半回転（１８０度）分ずれた切欠マーク候補位置部分
【０１０３】
さて、以上の工程により選択された有効データに基づいて第１周縁形状信号６０を曲線近似するのであるが、かかる処理に先立って、ステップＳ１２２において無効データの補完を行うことができる。
【０１０４】
すなわち、ウェハＷは略円形の平面を有しているため、検出手段３４により検出された第１周縁形状信号６０は、図１２（ｂ）に示すように、１８０度の地点１２５を中心として点対象図形として現れる。従って、例えば、ステップＳ１０２において無効と判断されたデータ領域１０５ａから半回転（１８０度）分ずれた領域（図１２（ｂ）において丸で囲んだ領域１２６）が有効データとして残っている場合には、そのデータ領域１２６に含まれるデータに基づいてデータ領域１０５ａを補完することが可能である。なお、このデータ補完処理は必ず必要であるわけではなく、かかる処理を省略して、処理の高速化を図ることが可能であることは言うまでもない。
【０１０５】
以上の処理が終了した後、ステップＳ１２３に進み、第１曲線近似手段７６による正弦波近似または余弦波近似が行われる。その際に、本発明に係る位置決め装置においては、最小２乗法による正弦波近似または余弦波近似処理が行われるので、有効データ群から直接ウェハＷの偏心量および偏心方向を求めることが可能である。従って、従来の装置のように、偏心量および偏心方向を求めるために、有効データの中から代表点を選択するような前処理を省略することができる。
【０１０６】
以下に、Ｎ個の測定データ（θi，Ｙi）を正弦波を表す式（１）により最小２乗近似する方法について説明する。ただし、上記ただし書き条件により、正弦波近似を行うデータは９０度ずれた４つのデータの集合でなければならない。
【０１０７】
【数９】

【０１０８】
なお、余弦波は下記の式（１）’により表される。
【０１０９】
【数１０】

【０１１０】
余弦波近似の場合にも、式（１）’により、正弦波近似とほぼ同様の手順でウェハＷの偏心量および偏心方向を求める。したがって、その詳細な説明は本明細書では省略する。
【０１１１】
ここに、最小２乗法とは、
【０１１２】
【数１１】

【０１１３】
が極小となるようなａ、φ、ｃを求めることである。
【０１１４】
【数１２】

【０１１５】
さらに上記を変形して、
【０１１６】
【数１３】

【０１１７】
ここで、測定データのθｉをπ／２ずれた４つのデータの集合となるように選ぶとすれば、第２項および第３項は０となり、
【０１１８】
【数１４】

【０１１９】
【数１５】

【０１２０】
ここで、測定データのθｉはπ／２ずれた４つのデータの集合であるから、
【０１２１】
【数１６】

【０１２２】
【数１７】

【０１２３】
さて、以上のように第１曲線近似手段７６により、第１周縁形状信号６０を正弦波近似して、第３周縁形状信号７８を求めた後、処理はステップＳ１２４に進む。そして、本発明によれば、上記正弦波近似式において、ウェハＷの中心の回転載置台４２の回転中心に対する偏心量ＥMおよび偏心方向ＥDは、それぞれ、ＥM＝｜ａ｜、ＥD＝−φ＋３π／２（ａ＞０）、ＥD＝−φ＋π／２（ａ＜０）とすることができるので、容易に偏心量および偏心方向を求めることが可能である。
【０１２４】
３．切欠マーク方向の計算
さらに処理は、切欠マーク方向の計算に進む。かかる切欠マーク方向を算出するためのアルゴリズムについて、図１３を参照しながら説明する。
【０１２５】
まずステップＳ１３１において、第２選択手段８２により切欠マーク位置の選択が行われる。既に説明したように、ステップＳ１１２において、第２周縁形状６４により切欠マークが存在する候補部分（１８０度位相がずれた２カ所）は同定されている。しかし、切欠マーク方向を算出するにあたっては、これらの切欠マーク候補部分から実際に切欠マークが存在している部分を確定する必要がある。
【０１２６】
ステップＳ１３１においては、図１３（ａ）に示すように、ステップＳ１０２で求めた第１周縁形状信号６０とステップＳ１２３で求めた第３周縁形状信号７８との差分を求める。第３周縁形状信号７８は第１周縁形状信号６０から切欠マーク部分を除いた部分が曲線近似されたものなので、求められた差分は、図１３（ａ）に実線８４で示すように、実際に切欠マークが存在する部分８６Ａを除いて、ほぼ水平の直線を示す。そこで、上記差分のうち、ステップＳ１１２において求めた切欠マーク候補部分の平均値（８６Ａ、８６Ｂ）を比較すれば、その平均値の高い部分（図示の例では、８６Ａ）に実際に切欠マーク部分が存在していると判断することができる。
【０１２７】
このようにして、切欠マーク部分８４Ａを確定した後、ステップＳ１３２に進み第２曲線近似手段８８による放物線近似が行われる。その際に、本発明に係る位置決め装置においては、最小２乗法による放物線近似処理が行われるので、有効データ群から直接切欠マークの方向を求めることが可能である。
【０１２８】
以下に、 Ｎ個の測定データ（θi，Ｙi）を２次式、
【０１２９】
【数１８】

【０１３０】
により最小２乗近似する方法について説明する。
ここに最小２乗法とは、
【０１３１】
【数１９】

【０１３２】
式（５）をａ₀、ａ₁、ａ₂でそれぞれ微分すると
【０１３３】
【数２０】

【０１３４】
【数２１】

【０１３５】
【数２２】

【０１３６】
さて、以上のように第２曲線近似手段８８により、切欠マークに対応する信号部分を放物線近似して、第４周縁形状信号９０を求めた後、処理はステップＳ１３３に進む。そして、本発明によれば、第３演算手段９２により、上記放物線近似式から、
β＝−ａ₁／２ａ₂’ （なぜなら、ｄｙ／ｄｘ＝０）
を求めることにより、切欠マーク方向を得ることができる。ここで、βは、図２２図示の如く、回転載置台の回転中心ＯＰを通る検出手段３４の光軸と、同回転中心ＯＰと切欠マークの最近接部Ｎｃ或いはＦｃとを結ぶ直線とがなす角度を表す。
【０１３７】
なお、切欠きマーク方向は、切欠きマークがオリエーテーションフラットである場合と、ノッチである場合とで、幾分意味が違ってくる。オリエーテーションフラットの場合は、必ずしも回転載置台の回転中心ＯＰからオリエーテーションフラットの中心に対する方向を示すわけではなく、同回転中心からオリエーテーションフラットに下ろした垂線の方向を示す。この点について、図２２を参照して以下に詳述する。なお、図２２における各記号の意味は次の通りである。
ＯＰ：回転載置台の回転中心
ＯＲ：搬送アームの回転中心
ＯＷｃ：補正前のウェハ中心
ＯＷｅ：補正後のウェハ中心
Ｆｃ：補正前のオリエーテーションフラットの最近接部
Ｆｅ：補正後のオリエーテーションフラットの最近接部
Ｎｃ：補正前のノッチの最近接部
Ｎｅ：補正後のノッチの最近接部
ｄ：偏心量
α：偏心方向角度
β：切欠きマーク方向角度
θａ：ウェハの向き補正角度
θｂ：搬送アームの回転補正角度
Ｒｘ：搬送アームの伸縮補正量
【０１３８】
まず、切欠きマークがノッチの場合、補正の前後で合同なΔＮｃ・ＯＰ・ＯＷｃと、ΔＮｅ・ＯＰ・ＯＷｅとに注目する。補正後には、Ｎｅ・ＯＷｅ・ＯＲは直線状に並び、ΔＯＰ・ＯＷｅ・ＯＲが形成される。
【０１３９】
【数２３】

【０１４０】
ΔＯＰ・ＯＷｅ・ＯＲに注目すると、
ｒｓｉｎθ_b＝ｄｓｉｎｔ
よって、
θ_b＝ｓｉｎ^-1｛（ｄ／ｒ）ｓｉｎｔ｝
Ｒ_X＝ｎ−ｒ＝ｒｃｏｓθ_b＋ｄｃｏｓｔ−ｒ
α＋θ_a＝ｔ＋θ_bより、
θ_a＝ｔ＋θ_b−α
【０１４１】
一方、切欠きマークがオリエーテーションフラットの場合、直線Ｎｅ・ＯＷｅと直線Ｆｅ・ＯＰとが平行となるため、式（６）において、
【０１４２】
【数２４】

【０１４３】
さらに、図２２中にウェハの半分を一点鎖線で示すように、搬送アームの回転中心ＯＲとウェハＷの中心とを結ぶ直線に対して、切欠きマークの向きを時計回りに角度φだけ回転させて受け取る場合は、式（６）を、
【０１４４】
【数２５】

【０１４５】
以上のようにして、本発明に係る位置決め装置による一連の処理が終了する。このように、本発明によれば、一連の信号処理により、ウェハＷの中心の回転載置台４２の中心に対する偏心量および偏心方向と、ウェハＷの切欠きマークの位置とを同時に求めることが可能である。
【０１４６】
従って、従来の装置のように、ウェハＷの中心の位置合わせと、ウェハＷの切欠きマークの位置合わせと２ステップで行う必要が無くなり、１ステップで処理することができるので、ウェハＷの位置決め処理を高速化できる。
【０１４７】
また、その際に、従来の装置のように、検出手段によりサンプリングされた有効データ群の中から代表点を選択せずに、有効データ群を直接処理して、ウェハＷの偏心量および偏心方向、ウェハＷの切欠きマークの位置を求めることができるので、さらに処理の高速化を図れる。
【０１４８】
次に、本発明に係る位置決め装置により、回転載置台４２の中心に対する偏心量および偏心方向と、切欠きマークの位置とが求められたウェハＷを搬送アーム２６により受け取る一連の動作について、図１４を参照しながら説明する。
【０１４９】
まず図１６を参照しながら、従来の位置決め装置の動作について説明する。
従来の一般的な位置決め装置は、回転載置台上に配設された、ウェハＷを支持するためのＸＹスライダ４２ｓを有する。ウェハＷを位置決めする際は、回転載置台４２を回転させると共に、スライダ４２ｓを駆動し、あらかじめ決められた搬送アーム２６の延出し位置の中心１０５に対するウェハの中心１０２の偏心を矯正する。また、この際、搬送アーム２６の延出し方向の中心線１０９上に切欠きマークの中心１０６来るようにする。そして、搬送アーム２６を直線１０９に沿って移動させて、ウェハＷを受け取る。
【０１５０】
その場合に、従来の位置決め装置では、第１工程において、搬送アーム２６の延出し位置の中心１０５とウェハＷの中心１０２との偏心が予め矯正されているので、ウェハＷＮＯ中心１０２と切欠きマーク中心１０６を結ぶ直線１０８と、搬送アーム２６の固定軸１０４と延出し位置の中心１０５を通る直線１０９とが略一致する。従って、搬送アーム２６を上記直線１０９に沿って進入させることにより、正確にウェハを受け取ることが可能となる。
【０１５１】
これに対して、本発明に係る位置決め装置では、回転載置台４２にＸＹスライダを設けなくとも、ウェハＷを搬送アーム２６で正確に受け取ることが可能となる。すなわち、回転載置台４２の回転中心１００とウェハＷの中心１０２が偏心した状態では、ウェハＷを反そうアーム２６で正確に受け取ることが可能となる。しかしながら、回転載置台４２の回転中心１００とウェハＷの中心１０２が偏心した状態では、ウェハＷの中心１０２と切欠きマーク中心１０６を結ぶ直線１０８と、回転載置台４２の中心と搬送アーム２６の固定軸１０４を結ぶ直線１１０とを、図１６に示すように一致させることができない。従って、図１５に示すように、回転載置台４２の中心と搬送アーム２６の固定軸１０４を結ぶ直線１１０の延長線上に切欠きマークの中心１０６を持ってくるのみでは、搬送アーム２６により、正確に（すなわち、搬送アーム２６の進入線と、ウェハＷの切欠きマーク中心１０６と中心１０２とを結ぶ直線１０８とが一致するように）ウェハＷを受け取ることができない。
【０１５２】
そこで、本発明によれば、位置決め装置によりウェハＷの偏心量および偏心方向と、切欠きマーク位置とを検出した後、図１４に示すように、回転載置台４２を回転させて、ウェハＷの中心１０２と切欠きマーク中心１０６を結ぶ直線１０８の延長線上に搬送アーム２６の固定軸１０４が来るようにする。かかる操作により、搬送アーム２６の進入線とウェハＷの中心１０２と切欠きマーク中心１０６を結ぶ直線１０８とを一致させることが可能となり、正確にウェハＷを受け取ることが可能となる。
【０１５３】
以上、本発明に係る位置決め装置により、ウェハＷの偏心量および偏心方向と、切欠きマーク位置とを一連の処理により連続的に求める実施例について説明したが、本発明はかかる実施例に限定されず、切欠きマーク位置のみを求める場合に対しても適用することが可能である。以下、切欠きマーク位置のみを求める場合の、本発明の実施例に係る位置決め装置を、図１７を参照しながら説明する。
【０１５４】
この実施例に係る位置決め装置は、図１７に示すように、検出手段１２０と、演算手段１２２と、候補検索手段１２４と、評価および選択手段１２６とから構成されている。検出手段１２０は、図７に示す検出手段３４と同様のもので、ウェハＷの外縁形状を光学的に検出し、第１周縁形状信号１２８を得るためのものである。この第１周縁形状信号１２８は、検出手段１２０の後段に接続される演算手段１２２に送られる。
【０１５５】
演算手段１２２は、図７に示す第１演算手段３４と同様のもので、回転載置台４２に載置されたウェハＷの１回転（３６０度）分の第１周縁形状信号１２８を半周期（１８０度）分ずらして重ね合わせて、第２周縁形状信号１３０を得るためのものである。そして、第２周縁形状信号１３０においては、図示のように、半周期（１８０度）分ずれた曲線部分同士が相殺され（すなわち、ウェハＷの中心の回転載置台４２の回転中心に対する偏心分が相殺され）、切欠きマーク部のピーク部分１３２のみが顕著に現れる。
【０１５６】
第２周縁形状信号１３０を出力する演算手段１２２の後段には、候補検索手段１２４が接続されている。候補検索手段１２４は、図７に示すピーク抽出手段と同様に、第２周縁形状信号１３０において顕著になったピーク部分１３２を抽出する。候補検索手段１２４では、半周期分に重ねられた信号のみを処理対象としているので、抽出されたピーク部分１３４はあくまでも切欠きマーク候補であり、実際の切欠きマークは、抽出されたピーク部分又はその部分から半周期ずれた部分に存在する。図１７では、第１周縁形状信号１２８から、２つの切欠きマーク候補部分１３４、１３６を得た状態を示す。
【０１５７】
そこで、本実施例に係る位置決め装置では、候補検出手段１２４の後段に評価および選択手段１２６が接続されている。すなわち、評価および選択手段１２６においては、候補検索手段１２４により抽出された切欠きマーク候補部分１３４、１３６から実際に切欠きマークが存在する部分が選択される。
【０１５８】
その際には、図１８（Ａ）〜（Ｃ）に示すような予め設定された評価用パターンを利用することが可能である。この評価用パターンは、第１周縁形状信号１２８中の切欠きマーク候補部分１３４、１３６、すなわち第２周縁形状信号１３０に基づいて抽出されたピーク部分１３４又はそのピーク部分から半周期（１８０度）分ずれた部分１３６のそれぞれに対して積和演算することにより、切欠きマーク部分と装でない部分との際を際だたせるためのものである。なお積和演算とは、信号パターンＳｉと評価用パターンＰｉについて、ΣＳｉＰｉを計算することである。
【０１５９】
かかる評価用パターンとしては、図１８（Ａ）に示すような矩形波信号、図１８（Ｂ）に示すようなのこぎり波信号、あるいは図１８（Ｃ）に示すような放物線波信号などの、実質的に切欠きマークが存在する信号幅に相当する部分において上に凸のピークを有する各種パターンを使用することができる。
【０１６０】
このように評価用パターンを、２つの切欠きマーク候補部分に積和演算すれば、それぞれの候補部分の平均を取れば、実際の切欠きマークに対応する部分の積和信号１３８が他方の切欠きマーク候補に対応する部分の積和信号１４０に比較して顕著に高い値を示すので、当該積和信号１３８側に切欠きマークが存在することを容易に知ることができる。
【０１６１】
以上説明したように、本発明に係る位置決め装置によれば、従来の装置や方法に比較して、より高速にかつ正確に、回転載置台４２に載置されたウェハＷの偏心量および偏心方向、並びにウェハＷの切欠きマークの位置を知ることが可能である。従って、搬送アーム２６により所定の処理室に迅速かつ正確に移載することが可能である。
【０１６２】
なお、以上においては、本発明に係る位置決め装置を、図１に示すようなマルチチャンバ方式の処理システムに適用した場合を例に挙げて、本発明の説明を行ったが、これは、搬送アームによる移載動作の頻度が高いマルチチャンバ方式の処理システムにおいてこそ、本発明の優れた作用効果が顕著に発揮されるからであって、本発明をかかるシステムに限定する意味ではない。従って、本発明は、かかるマルチチャンバ方式の処理システムに限定されず、迅速かつ正確な移載作業が要求される枚葉式又はバッチ式の各種処理システム、例えばＣＶＤ装置、エッチング装置、スパッタ装置、アッシング装置、拡散装置、露光装置、検査装置に対しても適用できることは言うまでもない。
【０１６３】
さらにまた、上記実施例においては、主に、本発明をウェハの外周の一部を水平方向にフラットに切断した位置決め用切欠き部、いわゆるオリエンテーションフラットに適用した例について説明したが、本発明はかかる例に限定されず、ウェハの外周の一部を凹に切り欠いた位置決め用切欠き部、いわゆるノッチに対しても好適に適用することも可能である。
【０１６４】
図３に示すノッチに対して本発明を適用する場合であっても、図２に示すオリエンテーションフラットの場合と同様に、ノッチ部分において光の透過量は他の部分よりも大きくなるので、オリエンテーションフラットとほぼ同様の波形信号を得ることが可能である。従って、得られた第１周縁形状信号を本発明に従って処理することにより、ウェハＷの偏心量および偏心方向、並びにノッチの方向を、迅速かつ正確に知ることが可能である。
【０１６５】
【発明の効果】
以上説明したように、本発明によれば、ウェハの偏心量および偏心方向、並びに切欠マークの位置を算出するにあたり複数工程を要していた従来の位置決め装置に比較して、単数工程によりウェハの偏心量および偏心方向、並びに切欠マークの位置を求めることが可能なので、ウェハのアライメント処理速度を向上させることが可能である。
【０１６６】
さらに、本発明によれば、従来の装置や方法のように、検出信号の中から複数のポイントをサンプリングして処理を行うのではなく、サンプリングデータを実質的に全て使用するので、ノイズの影響を受け難く、精度の高いアライメントを行うことが可能である。
【図面の簡単な説明】
【図１】本発明の実施例に係る位置決め装置を有するマルチチャンバ型処理システムの概略装置構成を示す平面図である。
【図２】オリエンテーションフラットを有するウェハの平面図である。
【図３】ノッチを有するウェハの平面図である。
【図４】図１に示す位置決め装置の構造および動作を示す概略側面図である。
【図５】図１に示す位置決め装置の構造および動作を示す概略側面図である。
【図６】図１に示す位置決め装置の構造および動作を示す概略側面図である。
【図７】図１に示す位置決め装置に置いて実行される信号処理の例を示す説明図である。
【図８】図１に示す位置決め装置に置いて実行される信号処理の例を示す説明図である。
【図９】図１に示す位置決め装置に置いて実行される信号処理の例を示す説明図である。
【図１０】図７〜図９に示す信号処理の各工程におけるアルゴリズムを示す流れ図である。
【図１１】図７〜図９に示す信号処理の各工程におけるアルゴリズムを示す流れ図である。
【図１２】図７〜図９に示す信号処理の各工程におけるアルゴリズムを示す流れ図である。
【図１３】図７〜図９に示す信号処理の各工程におけるアルゴリズムを示す流れ図である。
【図１４】図１に示す位置決め装置および搬送装置との動作を示す概略平面図である。
【図１５】図１に示す位置決め装置および搬送装置との動作を示す概略平面図である。
【図１６】従来の位置決め装置および搬送装置の動作を示す概略平面図である。
【図１７】図１に示す位置決め装置において実行される信号処理の別の例を示す説明図である。
【図１８】図１７に示す信号処理で使用される評価用パターンの例を示す図である。
【図１９】図１に示す位置決め装置において処理される信号波形を示す図である。
【図２０】図１に示す位置決め装置において処理される信号波形を示す図である。
【図２１】図１に示す位置決め装置において処理される信号波形を示す図である。
【図２２】図１に示す位置決め装置および搬送装置の動作におけるアルゴリズムを説明するための概略平面図。
【符号の説明】
Ｗ 被処理体（ウェハ）
１０ 処理装置
３０ 位置決め装置
３２ 回転載置台ユニット
３４ 検出手段
４２ 回転載置台
５８ 制御装置
６２ 第１演算手段
６８ ピーク抽出手段
７０ データ無効化手段
７６ 第１曲線近似手段
８０ 第２演算手段
８２ 第２選択手段
８８ 第２曲線近似手段
９２ 第３演算手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a positioning apparatus and a processing system, and more particularly to an apparatus and a processing system having the apparatus for positioning a workpiece having a substantially circular dominant contour, and more particularly to a positioning apparatus in a semiconductor processing system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a semiconductor manufacturing apparatus, a wafer positioning device has been installed in order to carry a workpiece, such as a semiconductor wafer, into / from a predetermined processing chamber with high accuracy by a transfer means such as a transfer arm.
[0003]
Further, each wafer has a cut-out portion called a so-called orientation flat (WF) in which a part of the periphery of the wafer is linearly cut as a reference for positioning as shown in FIG. In addition, a notch portion called a notch (WN) in which a recess is formed in a part of the peripheral edge of the wafer as shown in FIG. 3 is formed. Hereinafter, in this specification, positioning marks formed on a peripheral portion of the object to be processed and including a notch portion such as an orientation flat or a notch are collectively referred to as a “notch mark” unless otherwise specified. I will decide.
[0004]
An example of the positioning device is described in US Pat. No. 4,880,348. The positioning device includes a rotary mounting table and optical means arranged to face each other so as to sandwich the peripheral edge of the wafer mounted on the rotary mounting table.
[0005]
At the time of positioning, the wafer is rotated on the rotary mounting table, and information on the peripheral shape (profile) of the peripheral edge of the wafer is obtained by optical means. Then, alignment is performed by obtaining the amount of eccentricity and the direction of eccentricity from the rotation center of the rotary mounting table of the wafer from the acquired information. Next, information on the peripheral shape of the peripheral edge of the wafer is obtained again, and the direction of the notch mark on the wafer is obtained from the information. Then, the rotary mounting table is rotated by a predetermined amount to perform alignment in the direction of the notch mark of the wafer with respect to the transfer arm.
[0006]
[Problems to be solved by the invention]
However, in the conventional positioning apparatus, it is necessary to align the notch mark of the wafer after performing the alignment of the eccentric amount of the wafer mounted on the rotary mounting table, so that the positioning operation requires two steps. . Therefore, there is a problem that a relatively long time is required for the processing.
[0007]
In the conventional positioning apparatus, a method of obtaining the center of the wafer based on, for example, the coordinates of three points sampled from the periphery of the wafer is common. Thus, since the conventional positioning device uses only the coordinates of the points, there is a problem that it is easily affected by noise of the optical system and the electric circuit system, and it is difficult to obtain high positioning accuracy.
[0008]
Further, when determining the above three points for determining the center of the wafer, it is necessary to remove notch mark data as a pre-processing, and as a result, there is a problem that it takes time for signal processing. Yes.
[0009]
Further, in the case of performing signal processing to select, for example, a notch mark with a conventional positioning device, it is common to use a differentiator as in the device described in Japanese Patent Publication No. 5-41017, for example. . However, according to the differential processing, notch marks can be easily selected, but there is a problem that they are easily affected by noise. Therefore, in this respect, it is difficult to obtain high positioning accuracy with the conventional apparatus.
[0010]
The present invention has been made in view of the problems of the conventional positioning device as described above, and is new and capable of performing alignment with high alignment accuracy at high speed, which is not easily affected by noise. An object is to provide an improved alignment apparatus and processing system.
[0011]
[Means for Solving the Problems]
  In order to solve the above problem, the contour according to the first aspect of the present inventionIs a circleA positioning apparatus for positioning an object to be processed having a shape and a positioning notch at an outer edge portion includes a rotatable mounting table for supporting the object to be processed, and a mounting table as claimed in claim 1. A detection means for optically detecting the outer edge shape of the object to be processed on the mounting table, and a first peripheral shape signal for 360 degree rotation of the object to be processed outputted from the detection means are shifted by 180 degrees to overlap the second peripheral edge First calculation means for obtaining a shape signal, peak extraction means for extracting a peak portion from the second peripheral shape signal, a predetermined range including the peak portion of the first peripheral shape signal, and a range shifted by 180 degrees from the range Invalidating means for invalid data, first curve approximating means for obtaining a third peripheral shape signal by approximating the first peripheral shape signal based on valid data obtained by removing invalid data from the first peripheral shape signal, 3rd peripheral shape signal Is characterized in that a second computing means for obtaining the eccentric direction and the eccentric amount of the object with respect to the rotation center of the mounting table Zui.
[0012]
According to a second aspect of the present invention, the apparatus may further include a data complementing unit that complements the invalid data portion of the first peripheral shape signal based on the remaining valid data and converts it into valid data.
[0013]
According to a third aspect of the present invention, the first curve approximating means includes sine wave approximating means, and the sine wave approximating means represents N measurement data (θi, Yi) as a sine wave by the following formula. You may comprise so that a square approximation may be carried out.
[0014]
[Equation 5]

[0015]
At this time, as described in claim 4, the sine wave approximating means is configured such that the eccentric amount EM of the object to be processed with respect to the rotation center of the mounting table is EM = | a |, and the eccentric direction ED is ED = −φ + 3π / 2 ( It is preferable that a> 0) and ED = −φ + π / 2 (a <0) are set.
[0016]
Further, as described in claim 5, the first curve approximating means includes cosine wave approximating means. The cosine wave approximating means minimizes N pieces of measurement data (θi, Yi) by the following expression representing the cosine wave. You may comprise so that a square approximation may be carried out.
[0017]
[Formula 6]

[0018]
At this time, as described in claim 6, the cosine wave approximation means sets the eccentric amount EM of the object to be processed with respect to the rotation center of the mounting table to EM = | a |, and sets the eccentric direction ED to ED = −φ + π (a>). 0) and ED = −φ (a <0).
[0019]
Further, as described in claim 7, in the positioning device, a first driving means for rotationally driving the mounting table, a turnable and extendable transfer arm for receiving an object to be processed from the mounting table, Second driving means for turning and extending and retracting the transfer arm, and control means for controlling the operation of the mounting table and the transfer arm via the first and second drive means based on the eccentric direction and the eccentric amount. Further, it may be provided.
[0020]
In addition, according to the eighth aspect of the present invention, the positioning device includes a first shift that is shifted by 180 degrees corresponding to the peak portion of the second peripheral shape signal based on the first peripheral shape signal and the third peripheral shape signal. A second selection unit that selects one of the two candidate portions of the peripheral shape signal as a portion corresponding to the notch, and a curve approximation of the first peripheral shape signal corresponding to the portion selected by the second selection unit And a second curve approximation means for obtaining a fourth peripheral shape signal, and a third calculation means for obtaining the direction of the notch from the rotation center of the mounting table based on the fourth peripheral shape signal. May be.
[0021]
Further, as described in claim 9, the second selecting means takes the difference between the first peripheral shape signal and the third peripheral shape signal, compares the average value of the difference data of the two candidate portions, It can be configured to determine that the candidate portion corresponds to the notch.
[0022]
Further, as described in claim 10, the second curve approximating means can be configured to approximate the N measurement data (θi, Yi) to the least squares by the following quadratic expression.
[0023]
[Expression 7]

[0024]
Furthermore, as described in claim 11, the third calculation means can be configured to obtain the angle β from the quadratic expression. Here, the angle β represents an angle formed by the optical axis of the detecting means passing through the rotation center of the mounting table and a straight line connecting the rotation center and the closest portion of the notch.
[0025]
[Equation 8]

[0026]
Further, according to a twelfth aspect of the present invention, the apparatus includes a first driving means for rotationally driving the mounting table, a swingable and extendable transfer arm for receiving the object to be processed from the mounting table, and a transfer arm. The operation of the mounting table and the transfer arm is controlled via the first and second driving means based on the second driving means for rotating and extending / contracting the drive and the eccentric direction, the eccentric amount and the direction of the notch. Control means may be provided.
[0027]
Furthermore, as described in claim 13, the transfer arm has a fixed shaft that is the center of rotation, and when the object to be processed is received by the transfer arm, the center of the object to be processed and the center of the notch are connected. You may comprise so that a to-be-processed object may be positioned by rotating a mounting base so that a fixed axis may come on the extended line of a straight line.
[0028]
  Contours constructed according to another aspect of the present inventionIs a circleA positioning apparatus for positioning an object to be processed which has a shape and has a positioning notch at the outer edge portion, as described in claim 14, supports a workpiece and is rotatable, and a mounting table A detection means for optically detecting the outer edge shape of the upper object to be processed, and a first peripheral shape signal output from the detection means for a 360 degree rotation of the object to be processed is shifted by 180 degrees and superimposed. As a part corresponding to the notch part, the calculation means for obtaining the signal and extracting the peak part from the second peripheral shape signal, and the two candidate parts of the first peripheral shape signal corresponding to the peak part shifted by 180 degrees from each other It is characterized by comprising candidate search means for searching, and evaluation and selection means for evaluating signals of two candidate parts and selecting one of the two candidate parts as a part corresponding to the notch.
[0029]
Further, according to claim 15, the evaluation and selection means of the positioning device performs a product-sum operation on a convex-shaped evaluation pattern for each of the two candidate portions, and averages the product-sum values of each other. You may comprise so that a value may be compared.
[0030]
According to a sixteenth aspect of the present invention, the apparatus includes a first driving means for rotationally driving the mounting table, a swivelable and extendable transport arm for receiving a workpiece from the mounting table, and a transport arm. Second driving means for rotating and extending / contracting driving, and control means for controlling the operation of the mounting table and the transfer arm via the first and second driving means based on signals from the evaluation and selection means Further, it may be provided.
[0031]
  According to yet another aspect of the present invention, the contourIs a circleA processing system for processing an object to be processed which has a shape and has a positioning cutout at an outer edge portion includes a plurality of processing chambers for storing the object to be processed and performing processing as claimed in claim 17. A rotatable mounting table for supporting the object to be processed outside the processing chamber, first driving means for rotationally driving the mounting table, and the object to be processed between the processing chamber and the mounting table. Transfer arm, second driving means for turning and extending and retracting the extendable arm, detection means for optically detecting the outer edge shape of the object to be processed on the mounting table, and the object to be processed output from the detection means A first calculation means for obtaining a second peripheral shape signal by superimposing the first peripheral shape signal for 360 degree rotation by 180 degrees, a peak extraction means for extracting a peak portion from the second peripheral shape signal, a first A predetermined range including the peak portion of the peripheral shape signal and The invalidation means that makes the range shifted by 180 degrees with respect to the range invalid data, and the third peripheral edge by approximating the first peripheral edge signal with a curve based on the valid data obtained by removing the invalid data from the first peripheral edge signal A first curve approximating means for obtaining a shape signal; a second calculating means for obtaining an eccentric direction and an eccentric amount of the workpiece with respect to the rotation center of the mounting table based on the third peripheral shape signal; and based on the eccentric direction and the eccentric amount. Control means for controlling the operation of the mounting table and the telescopic arm via the first and second driving means;
It is characterized by having.
[0032]
Further, according to claim 18, in the apparatus, the first peripheral shape shifted by 180 degrees corresponding to the peak portion of the second peripheral shape signal based on the first peripheral shape signal and the third peripheral shape signal. A second selection means for selecting one of the two candidate parts of the signal as a part corresponding to the notch, and a first peripheral shape signal corresponding to the part selected by the second selection means by curve approximation A second curve approximation means for obtaining a fourth peripheral shape signal; and a third calculation means for obtaining the direction of the notch from the rotation center of the mounting table based on the fourth peripheral shape signal; You may comprise so that operation | movement of a mounting base and an expansion-contraction arm may be controlled via a 1st and 2nd drive means based on the direction of eccentricity, the amount of eccentricity, and a notch part.
[0033]
Furthermore, as described in claim 19, the transfer arm has a fixed shaft that is the center of rotation, and when the object to be processed is received by the transfer arm, the center of the object to be processed and the center of the notch are connected. It is preferable that the object to be processed is positioned by rotating the mounting table so that the fixed axis comes on the straight extension line.
[0034]
  According to yet another aspect of the present invention, the contourIs a circleA processing system for processing an object to be processed having a shape and a notch for positioning at an outer edge portion includes a plurality of processing chambers for storing and processing the object to be processed, and an object to be processed outside the processing chamber. A rotatable mounting table for supporting, first driving means for rotationally driving the mounting table, a transport arm for transporting the object to be processed between the processing chamber and the mounting table, and a telescopic arm And a second driving means for extending and contracting driving, a detecting means for optically detecting the outer edge shape of the object to be processed on the mounting table, and a first peripheral edge of 360 degree rotation of the object to be processed output from the detecting means First calculation means for obtaining a second peripheral shape signal by superimposing the shape signal by 180 degrees and extracting the peak portion from the second peripheral shape signal, and the first periphery shifted by 180 degrees from each other corresponding to the peak portion Cut out two candidate parts of the shape signal Candidate search means for searching as a part corresponding to, evaluation and selection means for evaluating the signals of the two candidate parts, and selecting one of the two candidate parts as a part corresponding to the notch, evaluation and Control means for controlling the operation of the mounting table and the transfer arm via the first and second drive means based on a signal from the selection means is provided.
[0035]
According to another aspect of the present invention, there is provided a positioning method for positioning a workpiece having a substantially circular dominant contour and having a positioning notch at the outer edge.
Positioning device according to the present invention configured as described above, Processing system and positioning methodIt operates as described below.
[0036]
First, in the positioning apparatus according to the present invention, information relating to the outer edge shape of the object to be processed such as a wafer is optically detected by the detecting means. In that case, a simple apparatus can be constructed if the detection means is composed of a light emitting element and a light receiving element. In addition, if a CCD image sensor is used as the detection means, data that is easier to process can be obtained, so that the processing speed can be increased.
[0037]
Here, when the center of the wafer and the rotation center of the rotary mounting table completely coincide with each other, an optical signal is detected at the same position for one rotation (360 degrees). The position coordinates are plotted as a straight line A in the horizontal direction as shown in FIG. In addition, the convex part (peak part) B on the straight line A is a notch mark, which indicates that more light is transmitted as compared with other parts.
[0038]
However, since the center of the wafer and the rotation center of the rotary mounting table are actually eccentric, the position coordinates of the outer edge shape of the wafer are plotted as a curve C as shown in FIG. In addition, the convex part (peak part) D on the curve C is a part corresponding to a notch mark similarly to the convex part (peak part) B shown in FIG. 19, and more light compared with another part. Is transmitted.
[0039]
By the way, since the position coordinates of the outer edge shape of the object to be processed are rotated on the rotary mounting table, they have a period of 360 °. At the same time, when the shape of the object to be processed that is rotated on the rotary mounting table is a line object such as a circular shape such as a wafer, the sign of the phase of the position coordinate of the outer edge shape of the object to be processed is 180. If it is inverted at a frequency cycle and a notch mark or the like is removed, a substantially similar shape is shown at a cycle of 180 °.
[0040]
Accordingly, in the positioning device according to the first aspect of the present invention, the first peripheral shape signal indicating the position coordinates of the outer edge shape for one rotation (360 degrees) of the object to be processed is half-cycle (180). The second outer edge shape signals E and F in which the eccentricity between the rotation center of the rotary mounting table and the center of the wafer is canceled as shown in FIG.
[0041]
Next, a peak portion is extracted from the peripheral shapes E and F of the second outer edge shape signal. As described above, this peak portion is formed by extra transmission of light due to the presence of the notch mark. In this regard, in the first peripheral shape signal, since the peak portion D is on the curve C as shown in FIG. However, according to the present apparatus, since the eccentricity between the center of the wafer and the rotation center of the rotary mounting table is offset in the second peripheral shape signal, the peak portion can be easily detected.
[0042]
Since it is considered that a notch mark, that is, a notch for positioning, exists at the peak portion of the second peripheral shape signal or a portion shifted from the peak portion by a half period (180 degrees), the second viewpoint apparatus Then, any one of the above portions can be selected as a notch mark by the selection means.
[0043]
At that time, each of the portions where the cutout mark is considered to exist in the first peripheral shape signal, that is, the peak portion detected from the second peripheral shape signal or the portion shifted from the peak portion by a half period (180 degrees). On the other hand, for example, as shown in FIG. 18, a product-sum operation is performed on a preset evaluation pattern, so that the difference between the notch mark and the portion that is not so can be emphasized. As a result, the notch mark can be easily selected.
[0044]
Furthermore, according to the present apparatus, predetermined preprocessing is performed in order to obtain an eccentric amount and an eccentric direction of the center of the object to be processed with respect to the rotation center of the rotary mounting table. That is, the peak portion formed by the notch marks is unnecessary data for approximating the peripheral shape of the object to be processed in a curve and determining the eccentric amount and the eccentric direction from the approximate curve. Therefore, according to the present invention, the data of the first peripheral shape signal corresponding to the predetermined range including the peak portion obtained from the second peripheral shape signal by the peak extracting means and the range shifted by a half cycle (180 degrees) from the range. Are processed as invalid data by the data invalidation means.
[0045]
At this time, since the position of the notch mark is not specified each time in this apparatus, all candidate ranges in which the notch mark may exist are converted into invalid data, so that the data processing time can be shortened. Further, by complementing the invalidated data portion, more accurate positioning can be performed at high speed.
[0046]
Further, in the present apparatus, the first peripheral shape signal is obtained by approximating the data of the first peripheral shape signal excluding invalid data by the fourth device by the first curve approximation means. Thus, by approximating the data of the first peripheral shape signal with a curve, the peripheral shape of the object to be processed can be mathematically processed, and the processing speed can be increased.
[0047]
In the case of curve approximation, simplification and high speed processing can be achieved by approximating a sine wave by means of a sine wave approximation means. In particular, by approximating a sine wave by least squares, it is possible to select from valid data as in the past. Preprocessing for selecting specific data (for example, processing for selecting three representative points) becomes unnecessary.
[0048]
Furthermore, in the present apparatus, the center of the object to be processed and the rotation center of the rotary mounting table based on the peak portion (that is, the portion indicating the eccentric direction and the eccentric amount) of the peripheral shape signal approximated by the curve by the second calculation means. Since the eccentric direction and the eccentric amount can be mathematically processed, the processing speed can be increased.
[0049]
Furthermore, in the present apparatus, the position of the notch mark on the wafer is easily determined by the second selection means based on the first, second and third peripheral shape signals used for obtaining the eccentric amount and the eccentric direction of the wafer. can do. Note that by using a device having a differencer and a comparator as the second selection means, the device can be simplified and the processing speed can be increased.
[0050]
Furthermore, after the data of the candidate position of the notch mark is approximated to a quadratic curve by the second curve approximating means, for example, the least square approximating means, the position of the notch mark, for example, the center position of the notch mark is obtained by the third calculating means. be able to.
[0051]
When determining the position of the notch mark on the wafer as described above, the conventional apparatus determines the position of the notch mark again after performing the alignment of the eccentric amount of the wafer. Was necessary. In this regard, according to the present invention, since the position of the notch mark on the wafer can be obtained based on the same signal as that used for obtaining the amount and direction of eccentricity of the wafer, the wafer position can be determined in one step. Positioning can be performed, and the processing speed can be increased.
[0052]
In particular, the present invention can provide an excellent effect in a multi-chamber processing apparatus that requires a high frequency of operations for transferring wafers, and therefore has a high positioning frequency, and is required to increase the processing speed.
[0053]
Furthermore, according to the present invention, by performing positioning so as to bring the fixed axis of the transfer arm on a straight extension line connecting the center of the wafer and the center of the notch mark, the amount of eccentricity of the wafer can be obtained as in the conventional apparatus. Even if the alignment in the eccentric direction and the alignment of the notch mark of the wafer are not performed in two steps, the wafer whose the amount of eccentricity, the eccentric direction, and the position of the notch mark are determined by the present invention is operated once for the transfer arm. Can be handed over.
[0054]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of a positioning device and a processing system according to the present invention will be described below in detail with reference to the accompanying drawings.
[0055]
First, a multi-chamber processing system having a positioning device according to an embodiment of the present invention and having two or more vacuum processing chambers will be described with reference to FIG.
[0056]
As shown in the figure, the vacuum processing system includes the first to fourth four vacuum processing chambers 4A, 4B, 4C, and 4D, with the common transfer chamber (first transfer chamber) 2 as the center. The two preliminary vacuum chambers 6A and 6B and the first and second cassette chambers 8A and 8B are connected to form a multi-chamber processing apparatus 10 in which the processing chambers are arranged in a so-called cluster shape.
[0057]
These processing chambers are housed in a common sub-clean room 12 and are isolated from the atmosphere. In addition, a second transfer chamber 14 is connected adjacent to the sub-clean room 12 so that the object to be processed is transferred between the outside and the processing system 10.
[0058]
The first to fourth vacuum processing chambers 4A, 4B, 4C, and 4D are an assembly of apparatuses for continuously performing a predetermined process on the surface of a semiconductor wafer that is an object to be processed. For example, a processing system for forming a through hole in a silicon interlayer insulating layer formed on silicon of a wafer and forming a titanium film / titanium nitride film / tungsten film as a wiring material in the through hole is taken as an example. If it mentions, it can be set as the following structures.
A plasma etching apparatus for etching through holes in an interlayer insulating layer made of silicon oxide as the first vacuum processing chamber 4A.
A sputtering apparatus for forming a titanium layer as an ohmic contact layer with respect to the through hole as the second vacuum processing chamber 4B and forming a titanium nitride layer as a barrier layer on the titanium layer.
A CVD apparatus for forming a tungsten layer on the barrier layer as the third vacuum processing chamber 4C.
A plasma etching apparatus for etching back the tungsten layer formed in the through hole as the fourth vacuum processing chamber 4D.
[0059]
Note that the apparatus group described above is merely an example, and it is needless to say that the multi-chamber processing system 10 can be configured by combining various types and quantities of processing chambers according to the required processing.
[0060]
Here, the overall configuration of the processing system will be described. First, the second transfer chamber 14 and the outside communicate with each other via a door G1. In the second transfer chamber 14, for example, first to fourth cassette mounting tables 16A, 16B, 16C, and 16D are installed side by side. In the illustrated example, cassettes C1 and C2 are mounted on the first and third cassette mounting tables 16A and 16C. These cassettes C1 and C2 are for accommodating and transferring a predetermined number, for example, 24 wafers W.
[0061]
Further, a cassette transfer device 18 is installed in the second transfer chamber 14. The cassette carrying device is movable in parallel to the rows of the first to fourth cassette mounting tables 16A to 16D (in the illustrated example, in the direction of the arrow), and unprocessed wafers are accommodated by the carrying arm 18A. The desired cassette thus taken out is taken out and transferred to the cassette chambers 8A and 8B, and the cassette containing the processed wafers can be collected from the cassette chambers 8A and 8B.
[0062]
The second transfer chamber 14 is connected to the first cassette chamber 8A via a door valve G2, and to the second cassette chamber 8B via a door valve G3. Each of the first and second cassette chambers 8A and 8B is provided with a cassette stage (not shown) that can be raised and lowered. The first and second cassette chambers 8A and 8B and the common transfer chamber 2 are connected through gate valves G4 and G5.
[0063]
Each of the first and second cassette chambers 8A and 8B is configured to be airtight, and has an exhaust path and an air supply path (not shown), and the inside thereof can be adjusted to a desired pressure atmosphere. Therefore, when the door valves G2 and G3 are opened (the gate valves G4 and G5 are closed), the atmosphere between the second transfer chamber 14 and the first and second cassette chambers 8A and 8B should be set to substantially the same pressure. it can. On the contrary, when the gate valves G4 and G5 are opened (the door valves G2 and G3 are closed), the common transfer chamber 2 and the first and second cassette chambers 8A and 8B can have substantially the same pressure atmosphere. .
[0064]
The common transfer chamber (first transfer chamber) 2 is formed of an airtight chamber having a substantially circular plane, and as described above, the first and second cassette chambers 8A, 8B, and connected to the first to fourth vacuum processing chambers 4A to 4D via gate valves G6, G7, G8, and G9. These vacuum processing chambers 4A to 4D are, for example, an etching apparatus, a sputtering apparatus, or a CVD apparatus as described above, and a wafer is placed on and fixed to the mounting tables 20A, 20B, 20C, and 20D accommodated in each chamber. Although a predetermined process is performed, a detailed description of the structure is omitted here.
[0065]
Furthermore, the common transfer chamber (first transfer chamber) 2 is connected to the first and second preliminary vacuum chambers 6A and 6B via communication paths 22A and 22B. In the first and second preliminary vacuum chambers 6A and 6B, mounting tables 24A and 24B are accommodated. On these mounting tables 24A and 24B, a heating unit for heating the mounted wafer and a cooling unit for cooling the mounted wafer are mounted. It is configured so that it can be cooled.
[0066]
Further, in the common transfer chamber 2, a transfer means 28 having a transfer arm 26 is installed almost at the center. The transfer arm 26 is composed of, for example, an articulated arm, and is disposed around the common transfer chamber 2. The first to fourth vacuum processing chambers 4 </ b> A to 4 </ b> D, the first and second preliminary vacuum chambers are provided. A predetermined wafer can be transferred between the 24A and 24B and the first and second cassette chambers 8A and 8B.
[0067]
Further, a positioning device 30 for aligning the wafer as the object to be processed is disposed on the first and second cassette chambers 8A and 8B side of the transfer chamber 2. The positioning device 30 is mainly composed of a rotary mounting table unit 32 and an optical detection means 34, and details thereof will be described later.
[0068]
The first to fourth vacuum processing chambers 4A to 4B and the common transfer chamber 2 also have an exhaust path and an air supply path (not shown) as in the first and second cassette chambers 8A and 8B. is set up. Therefore, if necessary, after opening and closing a predetermined gate valve, a predetermined processing gas or purge gas is introduced into each room via an air supply path, or each chamber is brought to a predetermined pressure atmosphere via an exhaust path. It can be controlled individually.
[0069]
As described above, the multi-chamber type vacuum processing system 10 including the positioning device according to the embodiment of the present invention is configured. Now, in the multi-chamber processing system 10 configured as described above, in order to carry a wafer into and out of a predetermined processing chamber with high accuracy, it is necessary to receive the wafer W with high accuracy by the transfer arm 26. is there. Therefore, normally, the center of the wafer W transferred by the transfer arm 26 and the notch mark are once aligned by the positioning device 30 according to the present invention, and then the wafer W is again received by the transfer arm 26, It is configured to be transferred to the processing chamber.
[0070]
Next, the configuration of the positioning device 30 will be described with reference to FIG. The illustrated positioning device 30 is mainly composed of a rotary mounting table unit 32 and detection means 34.
[0071]
The rotary mounting table unit 32 includes a driving unit 36, a rotary driving shaft 40 installed on the driving unit 36 via a bellows 38, and a disk-shaped rotating mounting table 42 fixed on the rotary driving shaft 40. It is configured. Therefore, the rotary mounting table 42 can be moved up and down by the bellows 38 and can be rotated by a predetermined amount by the power transmitted from the drive unit 36 via the rotary drive shaft 40. The outer diameter of the rotary mounting table 42 is configured to be smaller than the outer diameter of the wafer W, but it is preferable that the rotary mounting table 42 has a size that can sufficiently support the wafer W during rotation. Further, a rubber pad or an electrostatic chuck pad (not shown) is installed on the upper surface of the rotary mounting table 42, and the wafer W can be fixed against a centrifugal force during rotation.
[0072]
In the example shown in the figure, the detection means 34 is composed of a light emitting unit and a light receiving unit. The light emitting unit includes a light emitting element 44 such as a light emitting diode. Light emitted from the light emitting element 44 is received by the light receiving element 52 via the lens 46, the lower mirror 48, and the upper mirror 50, converted into a position signal, and then transmitted to the control unit 58 via the buses 54 and 56. Sent. The signal sent to the control unit 58 is subjected to predetermined processing by each signal processing means of the control unit 58, and the eccentric amount and the eccentric direction of the wafer and the direction of the notch mark are obtained. Such signal processing will be described in detail later. The control unit 58 controls the operations of the transfer arm 26 and the rotary mounting table 42 through the respective drive units 29 and 36 based on the information on the amount of eccentricity and the direction of eccentricity, the notched arm, and the like. Perform alignment.
[0073]
In the example shown in the figure, the detection means 34 is composed of the light emitting element 44 and the light receiving element 52, but the present invention is not limited to this example. For example, it goes without saying that the periphery of the wafer can be directly imaged by a CCD camera and processed as image data. As described above, when a CCD camera is used, signal data that is easier to process can be obtained, so that the processing speed can be increased.
[0074]
Since the positioning device 30 according to the present invention is configured as described above, it operates as shown in FIGS. That is, as shown in FIG. 4, the wafer W is transferred to the upper side of the rotary mounting table 42 by the transfer arm 26 with the rotary mounting table 42 lowered to the lower position. Next, as shown in FIG. 5, the rotary mounting table 42 is raised, the wafer W is transferred from the transfer arm 26 onto the rotary mounting table 42, and then the transfer arm 26 is retracted. Then, the wafer W is fixed on the rotary mounting table 42 by a rubber pad or an electrostatic chuck pad (not shown), thereby completing the preparation for the positioning process.
[0075]
Next, as shown in FIG. 6, the rotary mounting table 42 is further raised, and the rotary mounting table 42 is rotated together with the wafer W. Further, light is emitted from the light emitting element 44 and received by the light receiving element 52 through the lens 46 and the mirrors 48 and 50. At that time, the wafer W is mounted on the rotating mounting table 42 such that the periphery of the rotating wafer W crosses the optical path. Accordingly, information relating to the peripheral shape of the wafer W is collected by detecting light transmitted through the peripheral edge of the wafer W (that is, light that has not been blocked by the peripheral edge of the wafer W) during one rotation of the wafer W. Can do.
[0076]
Here, if the center of the wafer W coincides with the rotation center of the rotary mounting table 42, the peripheral shape of the substantially circular wafer is constant, and the detected signal is represented by a solid line A in FIG. It is plotted as a substantially horizontal straight line except for the portion B corresponding to the notch mark that transmits light. When positioning the wafer W, it is sufficient to determine the position of the portion B corresponding to the notch mark.
[0077]
However, in practice, as shown in FIGS. 2 and 3, the center OW of the wafer W and the rotation center OP of the rotary mounting table 42 are eccentric, and the detected signal C is shown by a solid line C in FIG. Thus, except for the portion D corresponding to the notch mark that transmits light, it is plotted as a substantially sinusoidal curve. Accordingly, when positioning the wafer W, not only the position of the portion D corresponding to the notch mark of the wafer W is detected, but also the eccentric amount and the eccentric direction of the center OW of the wafer W with respect to the rotation center OP of the rotary mounting table 42 are obtained. There is a need.
[0078]
For this purpose, in the positioning device 30 according to the present invention, the control unit 58 includes signal processing means as described below. Next, an example of signal processing means constituting the control unit 58 will be described with reference to FIGS. In FIGS. 7 to 9, the graphs shown below each signal processing means outline the signal processing executed by each signal processing means.
[0079]
As shown in FIG. 7, the outer edge shape of the wafer W optically detected by the detection means 34 is sent to the first calculation means 62 as a first peripheral shape signal 60 (60A, 60B). The first calculating means 62 superimposes the first peripheral shape signal 60 (60A, 60B) for one rotation (360 degrees) of the wafer W placed on the rotary mounting table 42 by shifting it by a half cycle (180 degrees). In addition, the second peripheral shape signal 64 is obtained. In the second peripheral shape signal 64, as shown in the figure, the curved portions shifted by a half period (180 degrees) cancel each other (that is, the eccentric portion of the center of the wafer W with respect to the center of the rotary mounting table 42). Only the peak portion 66 corresponding to the notch mark portion through which light has passed is remarkably represented.
[0080]
A peak extraction unit 68 is connected to the subsequent stage of the first calculation unit 62 that outputs the second peripheral shape signal 64. The peak extracting means 68 is for extracting a peak portion 66 that becomes prominent in the second peripheral shape signal 64. In this peak extraction means 68, only the signal superimposed for a half period is processed. Therefore, the extracted peak portion is a notch mark candidate position, and the actual notch mark is the extracted peak. It should be noted that it exists in a part or a part shifted from the part by a half cycle.
[0081]
Further, a data invalidating means 70 is connected to the subsequent stage of the peak extracting means 68. In the curve approximation process described later, since the peak signal portion appearing in the notch mark portion is unnecessary data, the data invalidation means 68 processes the signal of the notch mark portion as invalid data in advance. At that time, the data invalidating means 68 invalidates all notch mark candidate parts estimated from the peak portion extracted by the peak extracting means 68 (that is, the peak part 72 and the part 74 shifted from the part by a half cycle). To do. In this way, the processing speed can be increased by omitting the processing procedure for selecting the portion corresponding to the actual notch mark from the notch mark candidate portions.
[0082]
Although not shown in order to simplify the description, a data complementing unit for complementing the invalidated data portion based on the remaining valid data and converting it to valid data is provided after the data invalidating unit 68. It is also possible.
[0083]
Further, a first curve approximation unit 76 as shown in FIG. 8 is connected to the subsequent stage of the data invalidation unit 70. The first curve approximation means 76 obtains a third edge shape signal 78 by curve approximation of the first edge shape signal 60 based on valid data obtained by removing invalid data from the first edge shape signal 60. The first curve approximation means 76 is preferably a means for approximating the first peripheral shape signal 60 to a sine wave, and in particular, it is possible to perform direct sine wave approximation from the effective data group of the first peripheral shape signal 60. It is preferable to use the least square approximation method.
[0084]
Further, the second calculation means 80 is connected to the subsequent stage of the first curve approximation means 76. The second calculating means 80 obtains an eccentricity EM and an eccentric direction Ed with respect to the rotation center of the rotary mounting table 42 at the center of the wafer W from the third peripheral shape signal 78 approximated by the first curve approximation means 76. Is. As described above, according to the positioning device 32 of the present invention, as in the prior art, when determining the amount of eccentricity and the direction of eccentricity of the wafer W, preprocessing (for example, representative points) for selecting specific data from valid data The process of selecting three points is not necessary, and the amount of eccentricity and the direction of eccentricity of the wafer W can be directly obtained from the effective data group.
[0085]
Further, a second selection unit 82 is connected to the subsequent stage of the second calculation unit 80. As described above, the candidate portions (two locations) where the notch mark exists are clarified from the second peripheral shape signal 64. In determining the position of the notch mark, the notch mark candidate portion is actually used to determine the notch mark position. It is necessary to determine the part where exists. The portion where the notch mark actually exists is determined by the second selection means 82. In determining the portion corresponding to the notch mark, first, as shown by a solid line 84, for example, the difference between the first peripheral shape signal 60 and the third peripheral shape signal 78 is obtained. Next, the average values of the notch mark candidate portions 86A and 86B in the difference data 84 are compared with each other, and it can be determined that a notch mark exists in a portion with a high average value (86A in the illustrated example).
[0086]
Further, the second curve approximation means 88 is connected to the subsequent stage of the second selection means 82 as shown in FIG. The second curve approximation means 88 is used to obtain a fourth edge shape signal 90 by curve approximation of the first edge shape signal 60 corresponding to the notch mark portion selected by the second selection means 82. When obtaining the fourth peripheral shape signal 90, it is preferable to approximate the curve as a quadratic curve directly from the effective data group by the least square approximation method. Details of such processing will be described later.
[0087]
Further, a third calculation means 92 is connected to the subsequent stage of the second curve approximation means 88. The third computing means 92 is for obtaining the closest portion Nc or Fc of the notch mark with respect to the rotation center of the direct rotation mounting table 42 based on the peak value of the fourth peripheral shape signal 90 obtained by the second curve approximation means 88. belongs to.
[0088]
As described above, according to the positioning apparatus of the present invention, the amount of eccentricity and the eccentric direction of the center of the wafer W with respect to the center of the rotary mounting table 42 and the position of the notch mark on the wafer W are obtained by a series of signal processing. It is possible to obtain it at the same time.
[0089]
Therefore, unlike the conventional apparatus, it is not necessary to perform the alignment of the center of the wafer W and the alignment of the notch mark of the wafer W in two steps, and the processing can be performed in one step. Processing can be speeded up.
[0090]
At that time, as in the conventional apparatus, the effective data group is directly processed without selecting a representative point from the effective data group sampled by the detecting means, and the eccentric amount and the eccentric direction of the wafer W are processed. Since the position of the notch mark on the wafer W can be obtained, the processing speed can be further increased.
[0091]
Next, an embodiment of an algorithm for positioning the center of the wafer W and the notch mark by the positioning apparatus according to the present invention will be described with reference to FIGS.
[0092]
1. Pre-processing and search for notch mark candidate positions
First, as shown in FIG. 10, in step S101, noise is removed from the data indicating the peripheral shape of the wafer W sampled by the detection means 34. This noise removal is, for example, taking the average value of five neighboring sampling points, and if the data at a certain place protrudes more than a predetermined value from the average value before and after that, noise is included in that part. This is done by determining that the data is invalid.
[0093]
Next, in step S102, valid data is determined. As shown in FIG. 4, the optical detection means 34 generally measures the peripheral shape of the wafer W with a light beam having a certain width (indicated by a dotted line in the figure). Therefore, when the amount of eccentricity of the wafer W with respect to the rotary mounting table 42 is large and the orbit of the periphery of the wafer W exceeds the maximum width (Max) and the minimum width (Min) of the light beam, FIG. Effective sampling cannot be performed for the portions 105a, 105b, and 105c indicated by dotted lines. Therefore, in step S102, preprocessing for invalidating the data in the above portion is performed.
[0094]
Next, in step S103, the first calculation means 62 obtains the second peripheral shape 64 by shifting the first peripheral shape signal 60 sampled by the detection means 34 by a half period (180 degrees) and superimposing them, and the peak extracting means. The peak portion 66 of the second peripheral shape 64 is extracted by 68 (FIG. 10B).
[0095]
In step S104, the ratio of valid data is determined. For example, when the valid data is less than 3/10 of the sampling data for one rotation (360 degrees) (that is, as shown in FIG. 10C, the sampling data for the half rotation (180 degrees) superimposed) If it is less than 3/5, an error signal indicating that effective alignment processing cannot be performed is output, and a command to remount the wafer W onto the rotary mounting table 42 by the transfer arm 26 can be sent.
[0096]
Needless to say, the criterion for determining valid data is not limited to the above-described embodiment, and can be set to any numerical value according to the required accuracy.
[0097]
Further, in this embodiment, the error of the sampling data is determined after obtaining the second peripheral shape signal 64 by the first calculating means 62. A configuration in which an error in sampling data is determined based on the reference value can also be employed.
[0098]
Next, the process proceeds to step S111 shown in FIG. 11, and the average value and standard deviation of the data superimposed in step S103 are calculated. In that case, valid data excluding a range of ± 36 degrees from the position of the peak value (maximum value) detected in step S103 (the part circled in FIG. 11A) is targeted. For example, when an orientation flat as shown in FIG. 2 is used as a notch mark, the orientation flat is normally designed to be within a range of 36 degrees around the entire circumference of the wafer W. This is because the notch mark is considered to exist within a range of ± 36 degrees from the peak value 66, and by targeting valid data excluding that portion, a highly accurate average value and standard deviation can be obtained.
[0099]
Next, the process proceeds to step S112, and a search for a notch mark candidate position is performed. In that case, for example, it is possible to determine that a notch mark candidate exists in a portion exceeding the threshold value by using an average value (Ave.) + 4σ of the overlay data as a threshold value. Here, not the notch mark position but the notch mark candidate position is referred to as the data to be processed in step S112 is the overlap data for half rotation, and therefore the actual notch mark This is because it is considered to exist in a portion determined to have a notch mark by processing or a portion shifted by a half rotation (180 degrees) from that portion.
[0100]
Next, the process proceeds to step S113, and it is determined whether the number of data existing in the notch mark candidate portion is less than three. That is, in subsequent processing, parabolic approximation by a quadratic equation is performed based on sampling data included in the notch mark portion, but in order to perform parabolic approximation by a quadratic equation, data on at least three points is necessary. is there. Accordingly, if the data is less than the data 3 present in the notch mark candidate portion, it is difficult to specify the notch mark portion, and an error signal is output.
[0101]
2. Calculation of eccentric amount and direction of wafer W
After completing the pre-processing as described above, the algorithm proceeds to a calculation process of the eccentric amount and the eccentric direction of the wafer W as shown in FIG. When determining the amount of eccentricity and the direction of eccentricity, in the positioning device 32 according to the present invention, as will be described later, a sine wave approximation of the first peripheral shape signal 60 is performed by the first curve approximation means 76. Since the data of the notch mark part causes the accuracy of the curve approximation to be lowered, it is necessary to remove in advance.
[0102]
Therefore, in step S121, the data invalidation means 70 invalidates the data included in the notch mark candidate portions (72 and 74 in FIG. 12A). The sampling data portion invalidated in the above process is as follows. -The part determined as noise in step S101
-The part determined to have exceeded the detection limit of the detection means 34 in step S102
-The part determined as the notch mark candidate position in step S112 and the notch mark candidate position part shifted from that part by half rotation (180 degrees)
[0103]
Now, the first peripheral shape signal 60 is approximated by a curve based on the valid data selected by the above process, but invalid data can be complemented in step S122 prior to such processing.
[0104]
That is, since the wafer W has a substantially circular plane, the first peripheral shape signal 60 detected by the detecting means 34 is a point around a point 125 of 180 degrees as shown in FIG. Appears as a target figure. Therefore, for example, when an area shifted by a half rotation (180 degrees) from the data area 105a determined to be invalid in step S102 (the area 126 circled in FIG. 12B) remains as valid data. The data area 105a can be complemented based on the data included in the data area 126. Needless to say, this data complementing process is not necessarily required, and it is possible to increase the processing speed by omitting such a process.
[0105]
After the above processing is completed, the process proceeds to step S123, where the first curve approximation means 76 performs sine wave approximation or cosine wave approximation. At that time, in the positioning device according to the present invention, since the sine wave approximation or cosine wave approximation processing by the least square method is performed, it is possible to directly obtain the eccentric amount and the eccentric direction of the wafer W from the effective data group. . Therefore, as in the conventional apparatus, in order to obtain the amount of eccentricity and the direction of eccentricity, preprocessing such as selecting a representative point from valid data can be omitted.
[0106]
Hereinafter, a method for approximating the N pieces of measurement data (θi, Yi) by least squares using the equation (1) representing a sine wave will be described. However, according to the above writing condition, the data to be approximated by the sine wave must be a set of four data shifted by 90 degrees.
[0107]
[Equation 9]

[0108]
The cosine wave is expressed by the following equation (1) ′.
[0109]
[Expression 10]

[0110]
Also in the case of cosine wave approximation, the amount of eccentricity and the direction of eccentricity of the wafer W are obtained by the same procedure as in the case of sine wave approximation by the expression (1) ′. Therefore, the detailed description is abbreviate | omitted in this specification.
[0111]
Here, the least squares method is
[0112]
## EQU11 ##

[0113]
Is to obtain a, φ, and c so that becomes minimum.
[0114]
[Expression 12]

[0115]
Furthermore, the above is modified,
[0116]
[Formula 13]

[0117]
Here, if the measurement data θi is selected to be a set of four data shifted by π / 2, the second term and the third term are 0,
[0118]
[Expression 14]

[0119]
[Expression 15]

[0120]
Here, θi of the measurement data is a set of four data shifted by π / 2.
[0121]
[Expression 16]

[0122]
[Expression 17]

[0123]
As described above, after the first curve shape means 76 approximates the first edge shape signal 60 to a sine wave to obtain the third edge shape signal 78, the process proceeds to step S124. According to the present invention, in the above sine wave approximate expression, the eccentricity EM and the eccentric direction ED with respect to the rotation center of the rotation mounting table 42 at the center of the wafer W are respectively expressed as EM = | a |, Ed = −φ + 3π / Since 2 (a> 0) and ED = −φ + π / 2 (a <0), the amount of eccentricity and the direction of eccentricity can be easily obtained.
[0124]
3. Calculation of notch mark direction
Further, the process proceeds to the calculation of the notch mark direction. An algorithm for calculating the notch mark direction will be described with reference to FIG.
[0125]
First, in step S131, the second selection means 82 selects a notch mark position. As already described, in step S112, candidate portions where two notch marks exist (two places with a phase difference of 180 degrees) are identified by the second peripheral shape 64. However, in calculating the notch mark direction, it is necessary to determine the part where the notch mark actually exists from these notch mark candidate parts.
[0126]
In step S131, as shown in FIG. 13A, the difference between the first peripheral shape signal 60 obtained in step S102 and the third peripheral shape signal 78 obtained in step S123 is obtained. Since the third peripheral shape signal 78 is obtained by approximating the portion obtained by removing the notch mark portion from the first peripheral shape signal 60 by a curve, the obtained difference is actually as shown by a solid line 84 in FIG. A substantially horizontal straight line is shown except for the portion 86A where the notch mark exists. Therefore, if the average value (86A, 86B) of the notch mark candidate portion obtained in step S112 is compared among the above differences, the notch mark portion is actually found in the portion with the higher average value (86A in the example shown). It can be determined that it exists.
[0127]
After confirming the cutout mark portion 84A in this way, the process proceeds to step S132, and parabolic approximation by the second curve approximation means 88 is performed. At that time, in the positioning device according to the present invention, since the parabolic approximation processing is performed by the least square method, the direction of the notch mark can be directly obtained from the effective data group.
[0128]
Below, N pieces of measurement data (θi, Yi) are expressed by a quadratic equation,
[0129]
[Formula 18]

[0130]
A method of least square approximation will be described.
Here, the least square method is
[0131]
[Equation 19]

[0132]
Equation (5) is expressed as a₀, A₁, A₂And differentiated by
[0133]
[Expression 20]

[0134]
[Expression 21]

[0135]
[Expression 22]

[0136]
As described above, the second curve approximation means 88 performs parabolic approximation of the signal portion corresponding to the notch mark to obtain the fourth peripheral shape signal 90, and then the process proceeds to step S133. And according to the present invention, the third calculating means 92 calculates the parabolic approximation from
β = −a₁/ 2a₂'(Because dy / dx = 0)
Is obtained, the notch mark direction can be obtained. Here, as shown in FIG. 22, β is formed by the optical axis of the detecting means 34 passing through the rotation center OP of the rotary mounting table and a straight line connecting the rotation center OP and the closest portion Nc or Fc of the notch mark. Represents an angle.
[0137]
Note that the notch mark direction has a slightly different meaning depending on whether the notch mark is an orientation flat or notch. In the case of the orientation flat, the direction from the rotation center OP of the rotary mounting base to the center of the orientation flat is not necessarily indicated, but the direction of the perpendicular line extending from the rotation center to the orientation flat is indicated. This point will be described in detail below with reference to FIG. The meaning of each symbol in FIG. 22 is as follows.
OP: Center of rotation of the rotating table
OR: Center of rotation of transfer arm
OWc: wafer center before correction
OWe: wafer center after correction
Fc: closest part of the orientation flat before correction
Fe: Nearest part of corrected orientation flat
Nc: closest part of notch before correction
Ne: Nearest part of the notch after correction
d: Eccentricity
α: Eccentric direction angle
β: Notch mark direction angle
θa: wafer orientation correction angle
θb: rotation correction angle of the transfer arm
Rx: Transfer arm expansion / contraction correction amount
[0138]
First, when the notch mark is a notch, attention is paid to ΔNc · OP · OWc and ΔNc · OP · OWe that are congruent before and after correction. After the correction, Ne · OWe · OR is arranged in a straight line to form ΔOP · OWe · OR.
[0139]
[Expression 23]

[0140]
Paying attention to ΔOP, OWe, OR,
rsinθ_b= Dsint
Therefore,
θ_b= Sin^-1{(D / r) sint}
R_X= N-r = rcos θ_b+ Dcost-r
α + θ_a= T + θ_bThan,
θ_a= T + θ_b-Α
[0141]
On the other hand, when the notch mark is an orientation flat, the straight line Ne · OWe and the straight line Fe · OP are parallel to each other.
[0142]
[Expression 24]

[0143]
Further, as shown by a one-dot chain line in FIG. 22, half of the wafer is rotated clockwise by an angle φ with respect to the straight line connecting the rotation center OR of the transfer arm and the center of the wafer W. To receive the expression (6),
[0144]
[Expression 25]

[0145]
As described above, a series of processing by the positioning device according to the present invention is completed. As described above, according to the present invention, the amount of eccentricity and the direction of the center of the wafer W with respect to the center of the rotary mounting table 42 and the position of the notch mark on the wafer W can be obtained simultaneously by a series of signal processing. It is.
[0146]
Therefore, unlike the conventional apparatus, it is not necessary to perform the alignment of the center of the wafer W and the alignment of the notch mark of the wafer W in two steps, and the processing can be performed in one step. Processing can be speeded up.
[0147]
At that time, as in the conventional apparatus, the effective data group is directly processed without selecting the representative point from the effective data group sampled by the detecting means, and the eccentric amount and the eccentric direction of the wafer W are processed. Since the position of the notch mark on the wafer W can be obtained, the processing speed can be further increased.
[0148]
Next, FIG. 14 shows a series of operations for receiving the wafer W by the transfer arm 26 for which the positioning device according to the present invention determines the amount and direction of eccentricity with respect to the center of the rotary mounting table 42 and the position of the notch mark. Will be described with reference to FIG.
[0149]
First, the operation of the conventional positioning device will be described with reference to FIG.
The conventional general positioning apparatus has an XY slider 42s for supporting the wafer W, which is disposed on a rotary mounting table. When positioning the wafer W, the rotary mounting table 42 is rotated and the slider 42s is driven to correct the eccentricity of the wafer center 102 with respect to the center 105 of the extension position of the transfer arm 26 determined in advance. At this time, the center 106 of the notch mark is positioned on the center line 109 in the extending direction of the transfer arm 26. Then, the transfer arm 26 is moved along the straight line 109 to receive the wafer W.
[0150]
In this case, in the conventional positioning apparatus, since the eccentricity between the center 105 of the extended position of the transfer arm 26 and the center 102 of the wafer W is corrected in advance in the first step, the wafer WNO center 102 and the notch mark A straight line 108 connecting the centers 106 and a straight line 109 passing through the fixed shaft 104 of the transfer arm 26 and the center 105 of the extension position substantially coincide with each other. Therefore, the wafer can be accurately received by moving the transfer arm 26 along the straight line 109.
[0151]
On the other hand, in the positioning device according to the present invention, the wafer W can be accurately received by the transfer arm 26 without providing the rotary mounting table 42 with an XY slider. That is, in a state where the rotation center 100 of the rotary mounting table 42 and the center 102 of the wafer W are decentered, the wafer W can be accurately received by the anti-arm 26. However, in a state where the rotation center 100 of the rotary mounting table 42 and the center 102 of the wafer W are eccentric, the straight line 108 connecting the center 102 of the wafer W and the notch mark center 106, the center of the rotary mounting table 42, and the transfer arm 26. The straight line 110 connecting the fixed shafts 104 cannot be matched as shown in FIG. Therefore, as shown in FIG. 15, if the center 106 of the notch mark is merely brought on the extended line of the straight line 110 connecting the center of the rotary mounting table 42 and the fixed axis 104 of the transport arm 26, the transport arm 26 In other words, the wafer W cannot be received (that is, the entry line of the transfer arm 26 coincides with the straight line 108 connecting the notch mark center 106 and the center 102 of the wafer W).
[0152]
Therefore, according to the present invention, the eccentric amount and direction of the wafer W and the position of the notch mark are detected by the positioning device, and then the rotary mounting table 42 is rotated as shown in FIG. The fixed shaft 104 of the transfer arm 26 is positioned on the extended line of the straight line 108 connecting the center 102 and the notch mark center 106. By such an operation, it becomes possible to make the approach line of the transfer arm 26 coincide with the straight line 108 connecting the center 102 of the wafer W and the notch mark center 106, and the wafer W can be received accurately.
[0153]
As described above, the embodiment has been described in which the positioning device according to the present invention continuously obtains the amount and direction of eccentricity of the wafer W and the notch mark position by a series of processes. However, the present invention is limited to such an embodiment. The present invention can also be applied to the case where only the notch mark position is obtained. Hereinafter, a positioning device according to an embodiment of the present invention in the case of obtaining only the notch mark position will be described with reference to FIG.
[0154]
As shown in FIG. 17, the positioning apparatus according to this embodiment includes a detection unit 120, a calculation unit 122, a candidate search unit 124, and an evaluation and selection unit 126. The detection unit 120 is the same as the detection unit 34 shown in FIG. 7, and is for optically detecting the outer edge shape of the wafer W and obtaining the first peripheral shape signal 128. The first peripheral shape signal 128 is sent to the calculation means 122 connected to the subsequent stage of the detection means 120.
[0155]
The calculation means 122 is the same as the first calculation means 34 shown in FIG. 7, and the first peripheral shape signal 128 for one rotation (360 degrees) of the wafer W placed on the rotary mounting table 42 is a half cycle ( The second peripheral shape signal 130 is obtained by superimposing by shifting by 180 degrees. In the second peripheral shape signal 130, as shown in the figure, the curved portions shifted by a half cycle (180 degrees) are canceled out (that is, the eccentricity of the center of the wafer W with respect to the rotation center of the rotation mounting table 42 is reduced). Only the peak portion 132 of the notch mark portion appears prominently.
[0156]
A candidate search unit 124 is connected to the subsequent stage of the calculation unit 122 that outputs the second peripheral shape signal 130. The candidate search unit 124 extracts the peak portion 132 that has become prominent in the second peripheral shape signal 130 in the same manner as the peak extraction unit illustrated in FIG. 7. Since the candidate search means 124 processes only the signals that are overlapped for half a cycle, the extracted peak portion 134 is a notch mark candidate to the last, and the actual notch mark is the extracted peak portion or It exists in the part shifted from the part by a half cycle. FIG. 17 shows a state where two notch mark candidate portions 134 and 136 are obtained from the first peripheral shape signal 128.
[0157]
Therefore, in the positioning device according to the present embodiment, the evaluation and selection unit 126 is connected to the subsequent stage of the candidate detection unit 124. That is, in the evaluation and selection means 126, a part where the notch mark actually exists is selected from the notch mark candidate parts 134 and 136 extracted by the candidate search means 124.
[0158]
In that case, it is possible to use a preset evaluation pattern as shown in FIGS. This evaluation pattern includes notch mark candidate portions 134 and 136 in the first peripheral shape signal 128, that is, the peak portion 134 extracted based on the second peripheral shape signal 130 or a half period (180 degrees) from the peak portion. This is to make the difference between the notch mark portion and the undressed portion stand out by performing a product-sum operation on each of the portions 136 that are separated. The product-sum operation is to calculate ΣSiPi for the signal pattern Si and the evaluation pattern Pi.
[0159]
As such an evaluation pattern, a rectangular wave signal as shown in FIG. 18 (A), a sawtooth wave signal as shown in FIG. 18 (B), or a parabolic wave signal as shown in FIG. It is possible to use various patterns having a convex peak upward in a portion corresponding to a signal width where a notch mark exists.
[0160]
In this way, if the evaluation pattern is subjected to product-sum operation on the two notch mark candidate parts, the average of each candidate part is obtained, and the product-sum signal 138 of the part corresponding to the actual notch mark is obtained. Since the value is significantly higher than the product sum signal 140 corresponding to the notch mark candidate, it can be easily known that the notch mark exists on the product sum signal 138 side.
[0161]
As described above, according to the positioning device according to the present invention, the amount of eccentricity and the direction of eccentricity of the wafer W placed on the rotary mounting table 42 are faster and more accurate than the conventional devices and methods. In addition, the position of the notch mark on the wafer W can be known. Therefore, the transfer arm 26 can quickly and accurately transfer to a predetermined processing chamber.
[0162]
In the above, the present invention has been described by taking the case where the positioning device according to the present invention is applied to a multi-chamber processing system as shown in FIG. 1 as an example. This is because the excellent operation and effect of the present invention can be remarkably exhibited only in a multi-chamber processing system having a high frequency of transfer operations due to the above, and the present invention is not limited to such a system. Therefore, the present invention is not limited to such a multi-chamber type processing system, and various single-wafer type or batch type processing systems that require a quick and accurate transfer operation, such as a CVD apparatus, an etching apparatus, a sputtering apparatus, Needless to say, the present invention can also be applied to an ashing device, a diffusion device, an exposure device, and an inspection device.
[0163]
Furthermore, in the above-described embodiments, the present invention has been mainly described with respect to an example in which the present invention is applied to a positioning notch portion obtained by cutting a part of the outer periphery of a wafer in a horizontal direction, so-called orientation flat. The present invention is not limited to such an example, and the present invention can also be suitably applied to a positioning notch portion in which a part of the outer periphery of the wafer is notched into a recess, that is, a so-called notch.
[0164]
Even when the present invention is applied to the notch shown in FIG. 3, the amount of light transmitted in the notch portion is larger than that in the other portions as in the orientation flat shown in FIG. It is possible to obtain substantially the same waveform signal. Therefore, by processing the obtained first peripheral shape signal according to the present invention, it is possible to quickly and accurately know the eccentric amount and the eccentric direction of the wafer W and the direction of the notch.
[0165]
【The invention's effect】
As described above, according to the present invention, the wafer eccentricity and the eccentric direction, and the position of the notch mark are calculated by a single process as compared with the conventional positioning apparatus that required a plurality of processes. Since the amount and direction of eccentricity and the position of the notch mark can be obtained, it is possible to improve the wafer alignment processing speed.
[0166]
Furthermore, according to the present invention, the sampling effect is not used by sampling a plurality of points from the detection signal as in the conventional apparatus or method. This makes it possible to perform highly accurate alignment.
[Brief description of the drawings]
FIG. 1 is a plan view showing a schematic apparatus configuration of a multi-chamber type processing system having a positioning apparatus according to an embodiment of the present invention.
FIG. 2 is a plan view of a wafer having an orientation flat.
FIG. 3 is a plan view of a wafer having a notch.
4 is a schematic side view showing the structure and operation of the positioning device shown in FIG. 1. FIG.
5 is a schematic side view showing the structure and operation of the positioning device shown in FIG. 1. FIG.
6 is a schematic side view showing the structure and operation of the positioning device shown in FIG. 1. FIG.
7 is an explanatory diagram showing an example of signal processing executed by being placed on the positioning device shown in FIG. 1; FIG.
FIG. 8 is an explanatory diagram showing an example of signal processing executed by being placed on the positioning device shown in FIG. 1;
FIG. 9 is an explanatory diagram showing an example of signal processing executed by being placed on the positioning device shown in FIG. 1;
10 is a flowchart showing an algorithm in each step of the signal processing shown in FIGS. 7 to 9; FIG.
11 is a flowchart showing an algorithm in each step of signal processing shown in FIGS. 7 to 9; FIG.
12 is a flowchart showing an algorithm in each step of signal processing shown in FIGS. 7 to 9; FIG.
13 is a flowchart showing an algorithm in each step of the signal processing shown in FIGS. 7 to 9; FIG.
14 is a schematic plan view showing the operation of the positioning device and the conveying device shown in FIG.
15 is a schematic plan view showing the operation of the positioning device and the conveying device shown in FIG.
FIG. 16 is a schematic plan view showing operations of a conventional positioning device and a conveying device.
FIG. 17 is an explanatory diagram showing another example of signal processing executed in the positioning device shown in FIG. 1;
18 is a diagram showing an example of an evaluation pattern used in the signal processing shown in FIG.
FIG. 19 is a diagram showing signal waveforms processed in the positioning device shown in FIG. 1;
20 is a diagram showing signal waveforms processed in the positioning device shown in FIG. 1; FIG.
FIG. 21 is a diagram showing signal waveforms processed in the positioning device shown in FIG. 1;
22 is a schematic plan view for explaining an algorithm in the operations of the positioning device and the conveying device shown in FIG.
[Explanation of symbols]
W Object to be processed (wafer)
10 Processing device
30 Positioning device
32 Rotary mounting table unit
34 Detection means
42 Rotating table
58 Controller
62 1st calculating means
68 Peak extraction means
70 Data invalidation means
76 First curve approximation means
80 Second calculation means
82 Second selection means
88 Second curve approximation means
92 Third operation means

Claims (22)

The positioning device for positioning the object to be processed with a notch for positioning the and outer edge contour circle shape,
A rotatable mounting table for supporting the object to be processed;
Detection means for optically detecting an outer edge shape of the object to be processed on the mounting table;
A first computing means for obtaining a superimposed second peripheral shape signal by shifting the first peripheral shape signal for 360 degree rotation of the object to be processed output from the detection means by 180 degrees;
Peak extraction means for extracting a peak portion from the second peripheral shape signal;
Invalidating means for making invalid data a predetermined range including the peak portion of the first peripheral shape signal and a range shifted by 180 degrees with respect to the predetermined range;
First curve approximation means for obtaining a third peripheral shape signal by approximating the first peripheral shape signal based on valid data obtained by removing invalid data from the first peripheral shape signal;
A positioning apparatus comprising: second computing means for obtaining an eccentric direction and an eccentric amount of the object to be processed with respect to the rotation center of the mounting table based on the third peripheral shape signal.   The positioning apparatus according to claim 1, further comprising a data complementing unit that complements the invalid data portion of the first peripheral shape signal based on the remaining valid data and converts the data into valid data. The first curve approximating means includes sine wave approximating means, and the sine wave approximating means approximates the least squares by the following formula, which represents N measurement data (θi, Yi) as sine waves. The positioning device according to claim 1 or 2.

  The sine wave approximating means sets the eccentricity EM of the object to be processed with respect to the rotation center of the mounting table as EM = | a |, the eccentric direction ED as ED = −φ + 3π / 2 (a> 0), and ED = −φ + π / The positioning device according to claim 3, wherein 2 (a <0) is set. E Bei cosine wave approximation means said first curve approximation means, said cosine wave approximation means, and characterized in that by the following equation representing the N measurement data (.theta.i, Yi) the cosine wave approximates least squares The positioning device according to any one of claims 1 to 4.

  The cosine wave approximation means sets the eccentricity EM of the object to be processed relative to the rotation center of the mounting table as EM = | a |, the eccentric direction ED as ED = −φ + π (a> 0), and ED = −φ (a < The positioning device according to claim 5, wherein 0) is set.   A first driving means for rotationally driving the mounting table, a swingable and extendable transfer arm for receiving the object to be processed from above the mounting table, and a second for rotating and extending and retracting the transfer arm The apparatus further comprises drive means and control means for controlling the operation of the mounting table and the transfer arm through the first and second drive means based on the eccentric direction and the eccentric amount. The positioning device according to claim 1. Based on the first peripheral shape signal and the third peripheral shape signal, one of two candidate portions of the first peripheral shape signal that are shifted by 180 degrees from each other corresponding to the peak portion of the second peripheral shape signal Second selection means for selecting one as a portion corresponding to the notch,
Second curve approximation means for obtaining a fourth edge shape signal by curve approximation of the first edge shape signal corresponding to the portion selected by the second selection means;
Third computing means for obtaining the direction of the notch from the rotation center of the mounting table based on the fourth peripheral shape signal;
The positioning device according to claim 1, further comprising:   The second selection means takes a difference between the first peripheral shape signal and the third peripheral shape signal, compares an average value of difference data of the two candidate portions, and one candidate portion has the notch portion. The positioning device according to claim 8, wherein the positioning device is determined to correspond to: 10. The positioning device according to claim 8, wherein the second curve approximation means approximates N pieces of measurement data (θi, Yi) by the following quadratic expression.

The third calculating means obtains an angle β from the following quadratic expression, where the angle β is the optical axis of the detecting means passing through the rotation center of the mounting table, and the rotation center and the nearest of the notch. The positioning device according to any one of claims 8 to 10, wherein the positioning device represents an angle formed by a straight line connecting the contact portion.

  A first driving means for rotationally driving the mounting table, a swingable and extendable transfer arm for receiving the object to be processed from above the mounting table, and a second for rotating and extending and retracting the transfer arm Drive means; and control means for controlling the operations of the mounting table and the transfer arm via the first and second drive means based on the eccentric direction, the eccentric amount, and the direction of the notch. The positioning apparatus according to claim 8, wherein the positioning apparatus is characterized by the above.   The transfer arm has a fixed axis that is the center of rotation thereof, and when receiving the object to be processed by the transfer arm, on a straight extension line connecting the center of the object to be processed and the center of the notch. The positioning apparatus according to claim 12, wherein the object is positioned by rotating the mounting table so that the fixed shaft comes. The positioning device for positioning the object to be processed with a notch for positioning the and outer edge contour circle shape,
A mounting table that supports and rotates the object to be processed;
Detection means for optically detecting an outer edge shape of the object to be processed on the mounting table;
Arithmetic means for shifting the first peripheral shape signal for 360 degree rotation of the object to be processed output from the detection means to obtain a superimposed second peripheral shape signal by shifting by 180 degrees;
A candidate for extracting a peak portion from the second peripheral shape signal and searching for two candidate portions of the first peripheral shape signal corresponding to the peak portion that are shifted from each other by 180 degrees as a portion corresponding to the notch Search means;
Evaluating and selecting means for evaluating the signals of the two candidate parts, and selecting either one of the two candidate parts as a part corresponding to the notch;
A positioning device comprising:   15. The evaluation and selection unit performs a product-sum operation on a convex evaluation pattern for each of the two candidate portions, and compares an average value of the product-sum values with each other. The positioning device described in 1.   A first driving means for rotationally driving the mounting table, a swingable and extendable transfer arm for receiving the object to be processed from above the mounting table, and a second for rotating and extending and retracting the transfer arm And further comprising a drive means and a control means for controlling the operation of the mounting table and the transfer arm via the first and second drive means based on the signals from the evaluation and selection means. The positioning device according to claim 13 or 14. Contour in a processing system for processing a workpiece having a notch for positioning the and the outer edge in the circular shape:
A plurality of processing chambers for storing and processing the object to be processed;
A rotatable mounting table for supporting the object to be processed outside the processing chamber;
First driving means for rotationally driving the mounting table;
A transfer arm for transferring the object to be processed between the processing chamber and the mounting table;
Second driving means for rotating and extending and retracting the telescopic arm;
Detection means for optically detecting an outer edge shape of the object to be processed on the mounting table;
A first computing means for obtaining a superimposed second peripheral shape signal by shifting the first peripheral shape signal for 360 degree rotation of the object to be processed output from the detection means by 180 degrees;
Peak extraction means for extracting a peak portion from the second peripheral shape signal;
Invalidating means for making invalid data a predetermined range including the peak portion of the first peripheral shape signal and a range shifted by 180 degrees with respect to the predetermined range;
First curve approximation means for obtaining a third peripheral shape signal by approximating the first peripheral shape signal based on valid data obtained by removing invalid data from the first peripheral shape signal;
Second computing means for obtaining an eccentric direction and an eccentric amount of the object to be processed with respect to the rotation center of the mounting table based on the third peripheral shape signal;
Control means for controlling the operation of the mounting table and the telescopic arm via the first and second drive means based on the eccentric direction and the eccentric amount;
A processing system comprising: Based on the first peripheral shape signal and the third peripheral shape signal, one of two candidate portions of the first peripheral shape signal that are shifted by 180 degrees from each other corresponding to the peak portion of the second peripheral shape signal Second selection means for selecting one as a portion corresponding to the notch,
Second curve approximation means for obtaining a fourth edge shape signal by curve approximation of the first edge shape signal corresponding to the portion selected by the second selection means;
A third computing means for obtaining a direction of the notch from the rotation center of the mounting table based on the fourth peripheral shape signal;
The control means controls the operations of the mounting table and the telescopic arm through the first and second driving means based on the eccentric direction, the eccentric amount, and the direction of the notch. The processing system according to claim 17.   The transfer arm has a fixed shaft that is the center of rotation thereof, and when the object to be processed is received by the transfer arm, the transfer arm has a linear extension line that connects the center of the object to be processed and the center of the notch. The processing system according to claim 18, wherein the workpiece is positioned by rotating the mounting table so that the fixed shaft comes. Contour in a processing system for processing a workpiece having a notch for positioning the and the outer edge in the circular shape:
A plurality of processing chambers for storing and processing the object to be processed;
A rotatable mounting table for supporting the object to be processed outside the processing chamber;
First driving means for rotationally driving the mounting table;
A transfer arm for transferring the object to be processed between the processing chamber and the mounting table;
Second driving means for rotating and extending and retracting the telescopic arm;
Detection means for optically detecting an outer edge shape of the object to be processed on the mounting table;
A first computing means for obtaining a superimposed second peripheral shape signal by shifting the first peripheral shape signal for 360 degree rotation of the object to be processed output from the detection means by 180 degrees;
A candidate for extracting a peak portion from the second peripheral shape signal and searching for two candidate portions of the first peripheral shape signal corresponding to the peak portion that are shifted from each other by 180 degrees as a portion corresponding to the notch Search means;
Evaluating and selecting means for evaluating the signals of the two candidate parts, and selecting either one of the two candidate parts as a part corresponding to the notch;
Control means for controlling the operation of the mounting table and the transfer arm via the first and second drive means based on the signal from the evaluation and selection means;
A processing system comprising: The positioning method for positioning a workpiece contour has a notch for positioning the and the outer edge in the circular shape,
The detection means optically detects the outer edge shape of the object to be processed supported on a rotatable mounting table,
The first calculation means shifts the detected first peripheral shape signal for 360 degree rotation of the detected object by 180 degrees to obtain a superimposed second peripheral shape signal,
A peak extraction means extracts a peak portion from the second peripheral shape signal;
The invalidation means sets the predetermined range including the peak portion of the first peripheral shape signal and a range shifted by 180 degrees with respect to the range as invalid data,
A first curve approximating unit including a sine wave approximating unit generates a first peripheral shape signal based on valid data obtained by removing invalid data from the first peripheral shape signal, and N measurement data (θi, Yi) as a sine wave. The third peripheral shape signal is obtained by approximating the least squares by the following formula 1
Based on the third peripheral shape signal, the second calculating means sets the eccentric amount EM of the object to be processed relative to the rotation center of the mounting table as EM = | a |, and sets the eccentric direction ED as ED = −φ + 3π / 2 (a > 0) and ED = −φ + π / 2 (a <0).

The positioning method for positioning a workpiece contour has a notch for positioning the and the outer edge in the circular shape,
The detection means optically detects the outer edge shape of the object to be processed supported on a rotatable mounting table,
The first calculation means shifts the detected first peripheral shape signal for 360 degree rotation of the detected object by 180 degrees to obtain a superimposed second peripheral shape signal,
A peak extraction means extracts a peak portion from the second peripheral shape signal;
The invalidation means sets the predetermined range including the peak portion of the first peripheral shape signal and a range shifted by 180 degrees with respect to the range as invalid data,
A first curve approximating unit including a cosine wave approximating unit obtains a first peripheral shape signal based on valid data obtained by removing invalid data from the first peripheral shape signal, and N measurement data (θi, Yi) as a cosine wave. The third peripheral shape signal is obtained by approximating the least squares by the following formula 1 ′,
Based on the third peripheral shape signal, the second calculation means sets the eccentric amount EM of the object to be processed relative to the rotation center of the mounting table as EM = | a |, and sets the eccentric direction ED as ED = −φ + π (a> 0). ), ED = −φ (a <0).

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