JP3715150B2 - Automatic image collection apparatus and method - Google Patents

Description

【００３６】
そこで、全体制御部（ホストコンピュータ）２０は、このＡ，Ｂ，Ｃ，ＤをＮ組の座標対［（ｘｎ，ｙｎ）、（Ｘｎ，Ｙｎ）］から求めることが可能となる。求めかたとしては、（ｘｎ，ｙｎ）と（Ｘｎ，Ｙｎ）各々の重心位置からオフセット［Ｃ、Ｄ］を求めた後に、擬似逆行列を利用した最小自乗法によりＡ、Ｂを求めれば良い。このように、全体制御部（ホストコンピュータ）２０は、（数１）式に基いて、画像自動収集装置３の位置座標（Ｘｎ，Ｙｎ）を算出するための欠陥検査装置２の位置座標（ｘｎ，ｙｎ）に対するずれ補正係数［Ａ，Ｂ，Ｃ，Ｄ］を算出することができる。
次に、ステップＳ４１０において、全体制御部（ホストコンピュータ）２０は、ｎ＝Ｎ＋１番目以降Ｍ番目までの順次小さくなる欠陥について、記憶装置２３に記憶された欠陥検査装置２から得られた欠陥位置座標（ｘｎ，ｙｎ）に対して上記（数１）式で示した変換式を用いてずれ補正を行って画像自動収集装置３の座標系における被対象基板１０上の欠陥位置座標（Ｘｎ，Ｙｎ）を算出する。
【００３７】
次に、ステップＳ４１１において、全体制御部（ホストコンピュータ）２０は、ｎ＝Ｎ＋１番目以降Ｍ番目までの順次小さくなる欠陥ｎについて、画像収集順に応じて、ステージ制御部１６を制御してステージ１１８を移動させて欠陥ｎが電子検出器１２０で撮像できるように光軸に位置決め（アライメント）を行う。次に、ステップＳ４１２において、全体制御部（ホストコンピュータ）２０は、メモリ部２４に記憶された欠陥寸法と撮像倍率との相関テーブルから記憶装置２３に記憶された欠陥ｎの寸法に対応する撮像倍率を選び出し、この選ばれた撮像倍率で撮像できるように走査偏向器１１３等（ステージ１１８の走査を組み合わせても良い。）による走査偏向量を制御し、その欠陥ｎの画像を寸法に対応する欠陥抽出倍率で電子検出器１２０で撮像し、撮像された欠陥画像信号が画像入力部１３に入力され、画像入力部１３でデジタル欠陥画像信号に変換され、さらに様々な補正やノイズ除去が行われて画像記憶装置１４に記憶されることになる。即ち、画像自動収集装置３の座標系にずれ補正されたことにより、被対象基板１０上に存在するｎ＝Ｎ＋１番目以降Ｍ番目までの順次小さくなる欠陥ｎを、寸法に対応する撮像倍率の視野内に位置付け（アライメント）することを可能にし、しかも欠陥ｎの画像を寸法に対応する撮像倍率で撮像することが可能となる。
【００３８】
次に、ステップＳ４１３において、画像収集順に応じて次の欠陥（ｎ＝ｎ＋１）が指定され、ステップＳ４１４において被対象基板上に存在する全ての欠陥についての画像入力が終えたら、ステップＳ４１５において被対象基板１０を搬送装置８にてステージ１１８にからアンロードし、次の被対象基板の欠陥撮像に進む。
【００３９】
以上の説明では、メモリ部２４に記憶された欠陥寸法と撮像倍率との相関テーブルに基いて欠陥寸法（欠陥サイズ）に対応する欠陥抽出倍率で撮像すると記したが、例えばｎ＝１〜Ｎ番目までのアライメント用の欠陥撮像時には固定された第１の撮像倍率を用い、ｎ＝Ｎ＋１〜Ｍ番目の欠陥は固定された第２の撮像倍率を用いる。このとき前述のようにアライメント用の第１の撮像倍率にて撮像された欠陥を用いて、さらに詳細な位置ずれ補正が可能となり、Ｎ＋１番目以降の欠陥撮像時に欠陥の位置出し精度（アライメント精度）を向上させることができ、その結果、位置出し後の欠陥の画像視野中心からのバラツキは小さくなり、第２の撮像倍率を第１の撮像倍率で得られる視野より狭い視野、すなわち高い倍率で撮像することが可能となる。即ち、第２の撮像倍率を、第１の撮像倍率よりも高い倍率に設定することが可能となる。このように、第２の撮像倍率を第１の撮像倍率より高い倍率に設定することにより、より微細な欠陥も画像上において高解像度でもって捉えることが可能となり、より微細な欠陥の特徴量（サイズ、形状、表面の状態、濃淡値等）を正確に抽出することができると共にその欠陥の性質（カテゴリー）について詳細解析して分類することが可能となる。特に、第２の撮像倍率をできるかぎり高い倍率（例えば５００００倍（０．０２μｍを１ｍｍとしてデジタル画像信号として撮像できる。）〜３００００倍（０．０２μｍを０．６ｍｍとしてデジタル画像信号として撮像できる。）、それ以上。）にすれば、欠陥の特徴量をより正確に抽出することができると共にその欠陥の性質（カテゴリー）についてより詳細に解析して分類することが可能となる。
上記具体例では、撮像倍率を欠陥撮像の目的に応じ２段階で切り替える場合について説明したが、前述のように欠陥寸法（欠陥サイズ）に応じてクラス分けを行い、欠陥寸法のクラスに応じて撮像倍率を決定しても構わない。また、画像上で観察される欠陥の大きさを予め指定された画像サイズ（単位：画素）で撮像する撮像倍率を適用する方法をとっても構わない。
【００４０】
次に、画像自動収集装置３が、欠陥検査装置２から取得される欠陥位置座標、被対象基板上の欠陥の個数、および欠陥の寸法を基に、より高い倍率で欠陥画像を取得する動作フローの第２の実施例について、図４Ａ、および図４Ｂを用いて説明する。
次に、第２の実施例において、図３に示す第１の実施例と相違するところについて説明する。
まず、第１は、ステップＳ４０１’において、ステップＳ４０１の内容に更に加え、画像処理装置１５において算出された欠陥サイズに対応する欠陥観察倍率を入力手段２１等を用いて入力して設定してメモリ部２４にテーブルとして記憶しておく点である。欠陥抽出倍率は、寸法の大きな欠陥については欠陥検査装置２の座標系と画像自動収集装置３の座標系との間の誤差を考慮して大きな欠陥を撮像視野内に位置付けできるように１００００倍以下の低めに決め、上記欠陥より寸法の小さい欠陥については欠陥検査装置２の座標系と画像自動収集装置３の座標系との間の誤差補正はされるが、欠陥検査装置２で検出される位置データ（ｘｎ，ｙｎ）にも検出誤差が含まれている関係で、上記寸法の小さい欠陥を撮像視野内に位置付けできるように５００００倍以下の低めの３００００倍程度に決めざるをえない。しかし、画像自動収集装置３の座標系で欠陥の位置（Ｘｎ，Ｙｎ）を検出し、再度欠陥を撮像視野の中心（光軸）に位置付けし直す（アライメントし直す）ことによって、欠陥を撮像しなおす欠陥観察倍率を欠陥抽出倍率よりも高めて欠陥サイズに対応させてより一層の高解像度を有する欠陥画像を取得することができる。
【００４１】
第２は、ステップＳ４０７ａにおいて、画像処理装置１５が、ステップＳ４０６で得られた欠陥画像信号と参照画像信号との間の欠陥を示す差画像信号を算出し、該算出された差画像信号から欠陥の位置（Ｘｎ，Ｙｎ）を検出すると共に欠陥を示す２値化画像信号から面積やＸ，Ｙ方向の長さ等で算出される欠陥サイズを検出する点である。
第３は、ステップＳ４０７ｂにおいて、ステップＳ４０７ａで検出された欠陥サイズがＨＵＧＥ Ｉで規定されるサイズより大きい場合、この欠陥は画像収集対象とせず、つぎの欠陥に順番をスキップさせる点である。これは、欠陥のサイズが大きく例えば撮像視野をはみ出す場合、正確なアライメントが期待できないなどの理由による。
第４は、ステップＳ４０７ｃにおいて、ステップＳ４０７ａで検出された欠陥の位置（Ｘｎ，Ｙｎ）を視野中心に位置決めし直し、再度検出された欠陥サイズに応じた欠陥観察倍率で撮像し、この撮像された欠陥画像信号を画像入力部１３に入力し、様々な補正およびノイズ成分消去等の処理を行って画像記憶装置１４に記憶して大きな欠陥のデジタル画像信号を取得する点である。これによって、大きな欠陥のデジタル画像信号を、欠陥抽出倍率よりも高い約１００００倍程度の欠陥観察倍率で撮像して高解像度で取得できるので、大きな欠陥についても全体制御部（ホストコンピュータ）２０において特徴量や欠陥の性質等を詳細解析して分類することが可能となる。
【００４２】
第５は、ステップＳ４１２ａにおいて、欠陥検査装置２から得られるＮ個の欠陥よりも小さい欠陥について該欠陥番号ｎの寸法に対応する欠陥抽出倍率で撮像して欠陥画像信号および参照画像信号を検出して画像入力部１３に入力し、様々な補正およびノイズ成分消去等の処理を行って画像記憶装置１４に記憶して欠陥画像信号および参照画像信号を取得する点である。
第６は、ステップＳ４１２ｂにおいて、画像処理装置１５が、ステップＳ４１２ａで取得された欠陥画像信号と参照画像信号との間の欠陥を示す差画像信号を算出し、この算出された差画像信号から欠陥の位置（Ｘｎ’，Ｙｎ’）を検出すると共に欠陥を示す２値化画像信号から面積やＸ，Ｙ方向の長さ等で算出される欠陥サイズを検出する点である。
第７は、ステップＳ４１２ｃにおいて、ステップＳ４１２ｂで検出された欠陥サイズがＨＵＧＥ IIで規定されるサイズより大きい場合、この欠陥は画像収集対象とせず、つぎの欠陥に順番をスキップさせる点である。これは、あるサイズ以上の欠陥は画像を収集して確認をする必要が無いという場合を想定した処理である。
【００４３】
第８は、ステップＳ４１２ｄにおいて、ステップＳ４１２ｂで検出された欠陥の位置（Ｘｎ’，Ｙｎ’）を視野中心に位置決めし直し、再度検出された欠陥サイズに応じた欠陥観察倍率で撮像し、この撮像された欠陥画像信号を画像入力部１３に入力し、様々な補正およびノイズ成分消去等の処理を行って画像記憶装置１４に記憶して大きな欠陥の画像信号を取得する点とである。このように、欠陥を撮像しなおす欠陥サイズに対応する欠陥観察倍率を欠陥抽出倍率よりも高めて欠陥サイズに対応させてより一層の高解像度を有する欠陥画像を取得することができる。その結果、小さな欠陥のデジタル画像信号を、欠陥抽出倍率よりも高い例えば５００００倍程度以上の欠陥観察倍率で撮像してより一層高解像度で取得できるので、大きな欠陥についても全体制御部（ホストコンピュータ）２０において特徴量や欠陥の性質等をより一層詳細解析して分類することが可能となる。以上説明した第１〜第８の点以外は、図３に示す第１の実施例と同様な動作および処理となる。
【００４４】
なお、ステップＳ４１２ｂおよびステップＳ４０７ａにおいて検出された欠陥サイズに関するデータでもって、記憶装置２３に記憶された欠陥検査装置２で検出された欠陥寸法に関するデータを更新することも可能である。また、ステップＳ４１２およびステップＳ４０７において検出された欠陥位置に関するデータも、欠陥検査装置２で検出される欠陥位置に関するデータよりも精度的に向上しているから、更新されることになる。
また、図４Ａと図４Ｂとは５０１と５０２とで接続されている。
なお、図３に示す前半のステップＳ４０１〜Ｓ４０９の後に図４Ｂに示すステップＳ４１０〜Ｓ４１４を実行してもよく、また図４Ａに示すステップＳ１０１’〜Ｓ４０９の後に図３に示す後半のステップＳ４１０〜Ｓ４１４を実行してもよい。
【００４５】
図５には、アライメントに用いる大きな欠陥（大きな欠陥として多くは１μｍ〜５μｍ程度である。）の個数Ｎ（５〜１０個程度）及びアライメントする時の欠陥抽出倍率（３０００〜７０００倍程度の低倍率：撮像視野として１０〜３０μｍ程度）を示す。この欠陥抽出倍率は、画像自動収集装置３において、欠陥検査装置２で検出された位置データを基に、被対象基板１０上に存在する大きな欠陥に対して３０００〜７０００倍程度の低倍率の撮像視野（１０〜３０μｍ程度）内に位置付けできることを示している。即ち、欠陥抽出倍率は、画像自動収集装置３の座標系と欠陥検査装置２の座標系との間の誤差の程度（１０〜２５μｍ程度以下）を示している。欠陥検査装置Ａが欠陥抽出倍率が３０００倍であることからして、検出される欠陥の位置精度が最も悪く、欠陥検査装置Ｃが欠陥抽出倍率が７０００倍であることからして、検出される欠陥の位置精度が最も良いことを示している。
【００４６】
このように、画像自動収集装置３の座標系と欠陥検査装置２の座標系との間に誤差があることからして、欠陥を撮像視野内に位置付けすることができるように撮像視野を１０〜３０μｍ程度に広げるために、撮像倍率を３０００〜７０００倍程度の低倍率にする必要がある。しかし、撮像倍率を３０００〜７０００倍程度の低倍率にすると解像度が低下して例えば１μｍ程度以下の欠陥を示すデジタル画像信号を得ることが困難になる。そこで、撮像倍率を３０００〜７０００倍程度の低倍率にして解像度が低下しても、撮像されて得られるデジタル画像信号から欠陥の位置が認識できる大きさの欠陥（約１μｍ〜５μｍ程度）について撮像すれば、少なくともその欠陥の位置（Ｘｎ，Ｙｎ）を検出でき、上記（数１）に基づくずれ補正係数［Ａ，Ｂ，Ｃ，Ｄ］を算出することが可能となって、欠陥抽出倍率を例えば１００００倍以上に高倍率にした場合においても、欠陥を撮像視野内に位置付けする（アライメントする）ことが可能となり、その結果、欠陥について高倍率に基づく高解像度を有するデジタル画像信号を取得することが可能となる。
【００４７】
いずれにしても、画像自動収集装置３において、欠陥検査装置２との関係で、初期状態でどれくらい座標がずれているか、与えられる座標はどれくらいばらついているかにより、アライメントのために必要な撮像視野サイズすなわち撮像倍率（欠陥抽出倍率）および大きな欠陥で示される座標点数（アライメント個数）Ｎを変える必要がある。これらの状態は、欠陥座標情報を出力する欠陥検査装置２に依存するので、図５に示すように欠陥検査装置種別ごとあるいは欠陥検査装置ごとに、欠陥寸法に応じた欠陥抽出倍率および大きな欠陥で示される座標点数Ｎを設定してメモリ部２４に記憶させれば良い。このように、全体制御部（ホストコンピュータ）２０は、画像自動収集装置３に投入される被対象基板１０がどの欠陥検査装置で検査されたのかの情報が入力されて記憶装置２３に記憶されているので、Ｓ４０６における欠陥抽出倍率（撮像倍率）を欠陥検査装置種別ごとあるいは欠陥検査装置ごとに制御することが可能となる。
【００４８】
また、全体制御部（ホストコンピュータ）２０は、ステップＳ４０６、およびステップＳ４１２において、欠陥寸法に対応する欠陥抽出倍率で撮像して得られ、画像記憶装置１４に記憶されるデジタル画像信号を、モニタ１８に表示することによって、メモリ部２４に設定記憶された欠陥検査装置種別ごとあるいは欠陥検査装置ごとの欠陥寸法に応じた欠陥抽出倍率および座標点数Ｎが適切であるか否かの確認をすることができる。なお、この際、全体制御部２０は、メモリ部２４に設定記憶された欠陥検査装置種別ごとあるいは欠陥検査装置ごとの欠陥寸法に応じた欠陥抽出倍率および座標点数（アライメント個数）Ｎのテーブルをモニタ１８に表示し、不適切の場合には、入力手段２１を用いてモニタ１８の画面上で修正することも可能である。
【００４９】
次に、欠陥の位置を認識するために更に、アライメントに最適な欠陥サイズＤを選択し、また、その欠陥の被対象基板（ウェハ）１０上での場所も考慮してアライメントを行い、より高い倍率で欠陥画像を取得する動作フローの第３の実施例について図６Ａおよび図６Ｂを用いて説明する。即ち、第３の実施例では、ステップＳ５０４においてアライメントブロック（ｎ：ｎ＝１，・・・，Ｎ）毎に欠陥サイズＤに最も近い欠陥座標（ｘⁿｋ，ｙⁿｋ）（ｋ＝１，・・・，Ｋ）を選択することによって、ずれ補正係数［Ａ，Ｂ，Ｃ，Ｄ］の算出を、被対象基板１０上において偏ることなく、全領域に亘って実質的にほぼ均等もしくは一様に算出できるようにしたことにある。
まず、ステップＳ５０１において、アライメント用に使用する被対象基板１０上における欠陥を被対象基板１０上のどの部分から選ぶかに関する情報を設定登録する。アライメント用の欠陥は、被対象基板１０上の全体（全領域）に亘って偏りやむらが無く、満遍無く実質的にほぼ均等もしくは一様に配置されていることが望ましい。これを実現するために、図７に示すように、被対象基板１０を幾つかのブロックに区分し、一ブロックから予め決められた数のアライメント用欠陥を選定するようにする。このブロックを以降、アライメントブロックと呼ぶ。アライメントブロックの例を図７に示す。図７（ａ）の例は、被対象基板１０を縦、横に格子状に区切り、その一区画をアライメントブロックとするものである。図７（ｂ）の例では、被対象基板１０上を同心円および放射状の線で区切り、その一区画をアライメントブロックとするものである。アライメント用の欠陥は、すべてのアライメントブロックあるいは一部のアライメントブロックから予め決められた数選定する。
【００５０】
以上具体的には、アライメントブロックの情報、すなわちアライメントブロックの形状及び使用する区画の情報、使用するアライメントブロックのブロック数をＮと、一ブロックに設定するアライメント用に使用する被対象基板１０上における欠陥の数Ｋとを予め入力手段２１を用いて入力してＲＡＭ等のメモリ部２４に記憶して設定登録する。なお、区分けされた各アライメントブロックの面積をほぼ一様にした場合、各アライメントブロックに対して設定される欠陥の数Ｋもほぼ一様にすればよい。区分けされた各アライメントブロックの面積に変動が有る場合には、各アライメントブロックに対して設定される欠陥の数Ｋをそれに応じて変えてもよい。要するに、アライメント用の欠陥が、被対象基板１０上の全体（全領域）に亘って偏りやむらが無く、満遍無く実質的にほぼ均等もしくは一様に配置できればよい。
ステップＳ５０１における欠陥寸法を基準とした欠陥を抽出するための撮像倍率（欠陥寸法に対する欠陥抽出倍率）の設定については第１の実施例と同様である。
【００５１】
次に、同じくステップＳ５０１にて、アライメント用に使用する被対象基板１０上における欠陥寸法Ｄを予め入力手段２１を用いて入力してＲＡＭ等のメモリ部２４に記憶して設定登録する。なお、予め、ＲＡＭ等のメモリ部２４に設定される欠陥寸法データとしては、欠陥検査装置２から取得される欠陥寸法の定義に従い、検出画像に対するＸ及びＹへの投影長のいずれか、即ちその大きい方、あるいはその小さい方、または両者の平均で定義する方法、直径で定義する方法、楕円近似を施した場合の長軸方向の寸法、あるいは短軸方向の寸法で定義する方法などが考えられる。
次に、ステップＳ５０２において、欠陥検査装置２からは画像自動収集装置３に投入される被対象基板１０上における欠陥数Ｍについての欠陥の位置座標、および欠陥の寸法情報がネットワーク２２または記録媒体等の入力手段２１を用いて読み込まれて記憶装置２３に記憶蓄積されている。
【００５２】
次に、ステップＳ５０３において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶蓄積された画像自動収集装置３に投入される被対象基板１０上における欠陥数Ｍについての欠陥の寸法情報に基づき、ステップＳ５０１で指定されたＮ個のアライメントブロックについて、各々のアライメントブロック内に含まれる欠陥をその寸法の大きな順番に並び替え、ステップ５０４で指定欠陥寸法Ｄに最も近い欠陥寸法を持つ欠陥をＫ個選択し、選択した順を該アライメントブロック内におけるアライメント順ｋとともにアライメントブロックｎにおけるｋ番目の欠陥座評点（ｘⁿｋ，ｙⁿｋ）として記憶装置２３に登録する。
そして、被対象基板１０を搬送装置８にてステージ１１８にロードする。
次に、ステップＳ５０５において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶蓄積された画像自動収集装置３に投入される被対象基板１０上における欠陥を用いたアライメントの順番としてのアライメントブロック番号ｎをｎ＝１と指定し、ステップＳ５０６において、指定されたアライメントブロック内における欠陥のアライメントの順番としての欠陥番号ｋをｋ＝１と指定する。
【００５３】
次に、ステップＳ５０７において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶されたアライメントブロック順ｎ＝１、アライメント欠陥順ｋ＝１からその欠陥の位置座標を基に、ステージ制御郎１６を駆動制御することによって被対象基板上の（ｘⁿｋ，ｙⁿｋ）に位置する欠陥が電子検出器１２０で撮像できるように被対象基板１０を載置したステージ１１８を移動させて該欠陥の位置決めを行う。
次に、ステップＳ５０８において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶されたアライメントブロック順ｎ＝１、アライメント欠陥順ｋ＝１からその欠陥の寸法に対応する欠陥抽出倍率を、メモリ部２４に設定されたテーブルから選びだし、この選びだされた倍率になるように低倍率の検出系（１１２等）に切り替えたり、走査偏向器１１３等（ステージ１１８の走査を組み合わせても良い。）による走査偏向量を拡大することによって低倍率が得られるように制御し、その欠陥の画像を低倍率で撮像する。このように寸法の大きい欠陥を、低倍率の撮像視野内に位置付けすることが可能となって、該欠陥の位置座標（ｘⁿｋ，ｙⁿｋ）を画像自動収集装置３の座標系で検出することが可能となる。なお、走査型電子顕微鏡１０１の場合、Ａ／Ｄ変換器１１６におけるデジタル変換するサンプリング周期は、低倍率の撮像時でも、高倍率の撮像時も一定とする。このようにサンプリング周期を一定とすると、低倍率の場合、サンプリング間隔が広がり、解像度は高倍率に比べ落ちることになる。しかしながら、欠陥寸法に合わせて撮像倍率を決めているので、欠陥寸法に対しては同じ解像度を得ることができる。また必要なら、撮像倍率に応じてサンプリング周期を変えることも可能である。
【００５４】
即ち、ステップＳ５０８において、全体制御部（ホストコンピュータ）２０は、メモリ部２４に設定されたアライメントブロックＮ個に含まれる各Ｋ個の欠陥の欠陥寸法に対応する撮像倍率で撮像するように走査偏向器１１３等（ステージ１１８の走査を組み合わせても良い。）による走査偏向量を制御することによって、電子検出器１２０によってアライメントブロックＮ個に含まれる各Ｋ個の欠陥を、その欠陥寸法に対応する欠陥抽出倍率で撮像され、画像入力部１３に入力され、画像入力郡１３においてデジタル画像信号に変換し、更に暗レベル補正、電子線の揺らぎ補正、およびシェーデイング補正等を行い、きらに疑似ノイズ成分を消去するフィルタリング処理を行って画像記憶装置１４に記憶されることになる。このように、アライメントブロックＮ個に含まれる各Ｋ個の欠陥についての撮像は、画像自動収集装置３の座標系で行われるので、画像自動収集装置３の座標系でのアライメントを兼ね備えることになる。この時の撮像倍率は、アライメント用欠陥画像を撮像するためにメモリ部２４に対して設定記憶された低倍率である固定倍率または可変倍率（走査偏向器１１３等を制御することによって得られる。）を用いても良い。
【００５５】
次に、ステップＳ５０９において、全体制御郎（ホストコンピュータ）２０からの指令に基いて、例えば隣接するチップの同一場所の画像を参照画像として、メモリ部２４に設定されたアライメントブロックＮ個に含まれる各Ｋ個の欠陥を、その欠陥寸法に対応する欠陥抽出倍率で撮像して画像入力装置１３に入力して画像記録装置（画像記憶装置）１４に記憶する。その結果、画像処理装置１５は、画像記録装置１４に記憶されたアライメントブロックＮ個に含まれる各Ｋ個の欠陥の欠陥画像と参照画像との欠陥を示す差画像を抽出し、この抽出された欠陥を示す差画像を例えば２値化画像信号に変換し、該変換された欠陥を示す２値化画像信号から例えば重心位置またはＸ方向およびＹ方向の中心位置を算出することによって画像内での欠陥の位置が検出されて全体制御部（ホストコンピュータ）２０に送信される。全体制御郡（ホストコンピュータ）２０は、画像処理装置１５から検出される画像内での欠陥の位置データを基に、位置モニタ用測長器で測定されるステージ１１８等の基準座標系（被対象基板１０がステージ１１８上に位置決めされて載置される関係で被対象基板１０上の基準座標系でもある。）に変換して被対象基板上の欠陥位置座標（Ｘⁿｋ，Ｙⁿｋ）を得て、記憶装置２３に記憶させることができる。
【００５６】
全体制御部（ホストコンピュータ）２０は、ステップＳ５１１において、ｋがメモリ部２４に設定されたＫになるまで、及びステップＳ５１３において、ｎがメモリ部２４に設定されたＮになるまで、以上説明した処理を繰り返すよう指令を出して、（Ｎ×Ｋ）組の座標対［（ｘⁿｋ，ｙⁿｋ）、（Ｘⁿｋ，Ｙⁿｋ）］を得る。（ｘⁿｋ，ｙⁿｋ）は欠陥検査装置（外観検査装置）２の座標糸で検出された欠陥の位置、（Ｘⁿｋ，Ｙⁿｋ）は画像自動収集装置３の座標系で検出された欠陥の位置であり、このこつの座標の違いはすなわち、欠陥検査装置２と画像自動収集装置３の間にある座標系のずれである。そこで、ステップＳ５１４において全体制御部（ホストコンピュータ）２０は、（Ｎ×Ｋ）組の座標対を用いて、このこつの座標系間の関係式を導出し、欠陥検査装置２の位置座標を画像自動収集装置３の位置座標に変換できるようにする。（ｘⁿｋ，ｙⁿｋ）→（Ｘⁿｋ，Ｙⁿｋ）の変換式は、第１の実施例で示した（数１）式で表わされる。全体制御部（ホストコンピュータ）２０は、この［Ａ，Ｂ，Ｃ，Ｄ］を（Ｎ×Ｋ）組の座標対［（ｘⁿｋ，ｙⁿｋ）、（Ｘⁿｋ，Ｙⁿｋ）］から求めることが可能となる。求めかたとしては、（ｘⁿｋ，ｙⁿｋ）と（Ｘⁿｋ，Ｙⁿｋ）各々の重心位置からオフセット［Ｃ，Ｄ］を求めた後に、擬似逆行列を利用した最小自乗法により［Ａ，Ｂ］を求めれば良い。このように、全体制御部（ホストコンピュータ）２０は、（数１）式に基いて、画像自動収集装置３の位置座標（Ｘⁿｋ，Ｙⁿｋ）を算出するための欠陥検査装置２の位置座標（ｘⁿｋ，ｙⁿｋ）に対するずれ補正係数［Ａ，Ｂ，Ｃ，Ｄ］を算出することができる。このように、ずれ補正係数［Ａ，Ｂ，Ｃ，Ｄ］を、全てのアライメントブロックＮに亘って被対象基板１０上において全領域に亘って均等に算出することができる。
【００５７】
次に、ステップＳ５１５において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶蓄積された画像自動収集装置３に投入される被対象基板１０上における欠陥数Ｍについてその撮像する順番を決定する。第１の実施例及び、第２の実施例では撮像順を欠陥の寸法順として説明したが、全ての欠陥を撮像するためのステージの合計の移動距離の観点からは最適である保証がない。このステージ移動距離を短くする（最も良いのは最小にする）という基準で欠陥の観察順を決定することにより、トータルの欠陥撮像時間を短縮できる利点がある。予め定まった位置にある平面上の複数の点を結ぶ最短の経路は、例えば伊里、腰塚「ｂｉｔ別冊、計算幾何学と地理情報処理」ｐｐ．ｌｌ０−１２１、共立出版（１９８６）に開示されている方法により求めることができる。従って、全体制御部（ホストコンピュータ）２０は、Ｍ個の欠陥について、記憶装置２３に記憶された欠陥検査装置２から得られた欠陥位置座標（ｘｎ，ｙｎ）に対して前述のようにステージ移動距離を最小の基準にしたがって欠陥を撮像する順番を決定し、並び替えた順番を画像自動収集装置３での画像収集順ｎとして記憶装置２３に設定登録する。なお、画像自動収集装置３に投入される被対象基板１０上における欠陥数がＭであることから、画像自動収集装置３で撮像対象する欠陥数はＭとなる。
【００５８】
次に、ステップＳ５１６（Ｓ４１０）において、上記（数１）式で示した変換式を用いてずれ補正を行って画像自動収集装置３の座標系における被対象基板１０上の欠陥位置座標（Ｘｎ，Ｙｎ）を算出する。そして、被対象基板１０を搬送装置８にてステージ１１８にロードする。
次に、ステップＳ５１７において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶蓄積された画像自動収集装置３に投入される被対象基板１０上における欠陥の画像収集順（この欠陥の画像収集順は、上記のように最短ルートで決定された観察順である。）ｎとしてｎ＝１を指定する。
次に、ステップＳ５１８（Ｓ４１１）において、全体制御郡（ホストコンピュータ）２０は、記憶装置２３に記憶された欠陥番号ｎ＝１からその欠陥の位置座標（Ｘｎ，Ｙｎ）を基に、ステージ制御部１６を駆動制御して被対象基板１０を載置したステージ１１８を移動させることによって、被対象基板上の（Ｘｎ、Ｙｎ）に位置する欠陥ｎが電子検出器１２０で撮像できるように欠陥ｎを光軸に位置決めを行う。
【００５９】
次に、ステップＳ５１９（Ｓ４１２）において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶された欠陥番号ｎ＝１からその欠陥寸法に対応する欠陥抽出倍率を、メモリ部２４に設定されたテーブルから選びだし、この選びだされた倍率になるように低倍率の検出系（１２０等）に切り替えたり、走査偏向器１１３等（ステージ１１８の走査を組み合わせても良い。）による走査偏向量を拡大することによって観察倍率が得られるように制御し、その欠陥の画像を撮像する。
次に、ステップＳ５２０（Ｓ４１３）において、画像収集順に応じて次の欠陥（ｎ＝ｎ＋１）が指定され、ステップＳ５２１（Ｓ４１４）において被対象基板上に存在する全ての欠陥についての画像入力が終えたら、ステップＳ５２２（Ｓ４１５）において被対象基板１０を搬送装置８にてステージ１１８にからアンロードし、次の被対象基板の欠陥撮像に進む。このようにＭ個の欠陥についての撮像が最短ルートで実現でき、撮像時間を短縮することができる。
【００６０】
以上の説明では、メモリ部２４に記憶された欠陥寸法と撮像倍率との相関テーブルに基いて欠陥寸法（欠陥サイズ）に対応する欠陥抽出倍率で撮像すると記したが、例えばアライメント用の欠陥撮像時には固定された第１の撮像倍率を用い、それ以外の欠陥撮像時、即ちステップＳ５１９における欠陥撮像には固定された第２の撮像倍率を用いる。このとき前述のようにアライメント用の第１の撮像倍率にて撮像された欠陥を用いて、さらに詳細な位置ずれ補正が可能となり、ステップＳ５１９における欠陥撮像時に欠陥の位置出し精度（アライメント精度）を向上させることができ、その結果、位置出し後の欠陥の画像視野中心からのバラツキは小さくなり、第２の撮像倍率を第１の撮像倍率で得られる視野より狭い視野、すなわち高い倍率で撮像することが可能となる。即ち、第２の撮像倍率を、第１の撮像倍率よりも高い倍率に設定することが可能となる。このように、第２の撮像倍率を第１の撮像倍率より高い倍率に設定することにより、より微細な欠陥も画像上において高解像度でもって捉えることが可能となり、より微細な欠陥の特徴量（サイズ、形状、表面の状態、濃淡値等）を正確に抽出することができると共にその欠陥の性質（カテゴリー）について詳細解析して分類することが可能となる。特に、第２の撮像倍率をできるかぎり高い倍率（例えば５００００倍（０．０２μｍを１ｍｍとしてデジタル画像信号として撮像できる。）〜３００００倍（０．０２μｍを０．６ｍｍとしてデジタル画像信号として撮像できる。）、それ以上。）にすれば、欠陥の特徴量をより正確に抽出することができると共にその欠陥の性質（カテゴリー）についてより詳細に解析して分類することが可能となる。
【００６１】
上記具体例では、撮像倍率を欠陥撮像の目的に応じ２段階で切り替える場合について説明したが、前述のように欠陥寸法（欠陥サイズ）に応じてクラス分けを行い、欠陥寸法のクラスに応じて撮像倍率を決定しても構わない。また、画像上で観察される欠陥の大きさを予め指定された画像サイズ（単位：画素）で撮像する撮像倍率を適用する方法をとっても構わない。
また、図６Ａと図６Ｂとは６０１と６０２とで接続されている。
次に、画像自動収集装置３が、欠陥検査装置２から取得される欠陥位置座標、被対象基板上の欠陥の個数、および欠陥の寸法を基に、より高い倍率で欠陥画像を取得する図８Ａ、および図８Ｂに示す動作フローの第４の実施例について、図６に示す第３の実施例と相違するところについて説明する。
【００６２】
まず、第１はステップＳ５０４ａにおいて被対象基板１０上に形成されたアライメント用のパターンを用いて検査装置２から送られてくる座標系を補正する点である。このアライメントパターンとは被検査基板１０上に形成される電子回路パターンと同様の製造プロセスを利用して作成されるものであり、その中心位置を確認容易とするために、円あるいは四角あるいは十字など対称性を持つ幾何学的な模様パターンで形成されたものである。異なる位置にあるアライメントパターンを少なくとも２個用いることにより、欠陥検査装置２におけるアライメントパターン（マーク）の位置座標（ｘ，ｙ）と画像自動収集装置３におけるアライメントパターンの位置座標（Ｘ，Ｙ）から、（数１）式を用いて、（ｘ，ｙ）→（Ｘ，Ｙ）へ変換するための座標変換係数［Ａ，Ｂ，Ｃ，Ｄ］を求めることが出き、（ｘ，ｙ）→（Ｘ，Ｙ）へ変換するための座標変換関数Ｇ：Ｇ（ｘ，ｙ）＝（Ｘ，Ｙ）を定めることができる。当然、欠陥検査装置２においてもアライメントパターンの位置座標（ｘ，ｙ）が検出され、画像自動収集装置３においてもアライメントパターンの位置座標（Ｘ，Ｙ）が検出されることになる。アライメントパターンの位置座標は、欠陥検査装置２と画像自動収集装置３とに共通する基準点となる。
【００６３】
第２は、ステップＳ５０７’において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶されたアライメントブロック順ｎ＝１、アライメント欠陥順ｋ＝１からその欠陥の位置座標を、ステップ５０４ａで導出した座標変換関数Ｇにより補正し、補正した位置座標Ｇ（ｘⁿｋ，ｙⁿｋ）を基に、ステージ制御部１６を駆動制御して被対象基板１０を載置したステージ１１８を移動させることによって被対象基板上のＧ（ｘⁿｋ，ｙⁿｋ）に位置する欠陥が電子検出器１２０で撮像できるように該欠陥の位置決めを行う点である。このように座標変換関数Ｇにより、アライメント用欠陥の位置出し精度（アライメント精度）を向上させることができ、その結果、位置出し後の欠陥の画像視野中心からのバラツキは小さくなり、確実なアライメントの実施が可能となる。
第３は、ステップＳ５１７’において、全体制御部（ホストコンピュータ）２０が、Ｘ及びＹ各々に対するオフセット値（offsetｘ，offsetｙ）を両者とも０として記憶装置２３に記憶蓄積する点である。
第４は、ステップＳ５１８’において、全体制御部（ホストコンピュータ）２０は、記憶装置２３に記憶された欠陥番号ｎ＝１から、隣接する前の点で求められたオフセット値（offsetｘ，offsetｙ）で補正された欠陥の位置座標（Ｘｎ＋offsetｘ，Ｙｎ＋offsetｙ）を基に、ステージ制御部１６を駆動制御して被対象基板１０を載置したステージ１１８を移動させることによって被対象基板上の（Ｘｎ＋offsetｘ，Ｙｎ＋offsetｙ）に位置する欠陥ｎが電子検出器１２０で撮像できるように欠陥ｎを光軸に位置決めを行う点である。このように、欠陥の位置座標（Ｘｎ，Ｙｎ）を、後述するように隣接する前の点で求められたオフセット値（offsetｘ，offsetｙ）で補正することによって、欠陥ｎを電子検出器１２０で撮像する視野内に高精度に位置決めすることが可能となる。
【００６４】
第５は、ステップＳ５１９ａにおいて、画像処理装置１５が、取得された欠陥画像信号から例えば参照画像信号を用いて、欠陥を示す差画像信号を算出し、この算出された差画像信号から欠陥の位置（Ｘｎ’，Ｙｎ’）を検出する点である。
【００６５】
第６は、ステップＳ５１９ｂにおいて、ステップＳ５１９ａで算出した欠陥の位置（Ｘｎ’，Ｙｎ’）とステップＳ５１６で補正関数を用いて算出した欠陥の位置（Ｘｎ，Ｙｎ）との差分からそのオフセット値（offsetｘ，offsetｙ）を算出する点である。このようにオフセット値（offsetｘ，offsetｙ）は、ステップＳ５１９ａで算出した欠陥の位置（Ｘｎ’，Ｙｎ’）とステップＳ５１６で補正関数を用いて算出した欠陥の位置（Ｘｎ，Ｙｎ）との差分から算出することが可能となる。
第３、第４、第５、第６で述べたオフセット値（offsetｘ，offsetｙ）は、アライメントにより得られた座標補正関数Ｆで処理して得られる欠陥座標値と、実際に欠陥の画像を取得して、画像より得られた真の欠陥座標値とのずれを表す。順次観察しようとする欠陥と欠陥との間のステージ移動は、最小の考え方に基いているので、観察順に基づく隣接する２点の欠陥は比較的近傍に存在し、オフセット値も小さい値で示されることになり、ステップＳ５１９ａにおいて欠陥画像信号を取得し、ステップＳ５１９ｂにおいてオフセット値を算出することが可能となる。このため算出されたオフセット値を次の欠陥の位置決めのときに用いれば、より正確な欠陥の位置決めが可能となる。
以上説明した第１、第６の点以外は、図６に示す第３の実施例と同様な動作および処理となる。
【００６６】
また、図８Ａと図８Ｂとは、６０１’と６０２’とで接続されている。
なお、図６Ａに示す前半のステップＳ５０１〜Ｓ５１４の後に図８Ｂに示すステップＳ５１５〜Ｓ５２２を実行してもよく、また図８Ａに示すステップＳ５０１、Ｓ５１４の後に図６Ｂに示す後半のステップＳ５１５〜Ｓ５２２を実行してもよい。
【００６７】
以上、画像自動収集装置３において、画像の撮像倍率を欠陥寸法に応じて設定する実施例について説明したが、画像の撮像倍率は撮像対象となる被対象基板（ウェハ基板）上の部分に形成された回路パターンの種類に応じて決定しても構わない。半導体ウェハ等の被対象基板上の回路パターンは微細なものであり、画像倍率が下がるということはこれをデジタル画像で捉える場合、サンプリング周波数が下がることを意味する。よって、このサンプリング周波数が被対象基板上に形成される回路パターンの空間周波数の半分以下になると、エイリアシングにより本来被対象基板上に存在しない一種の干渉縞のようなパターンが重畳し、これにより欠陥観察に困難を生じる恐れがある。このため、回路パターンの空間周波数が高い部分では撮像倍率（欠陥抽出倍率、欠陥観察倍率）を高く、空間周波数に低い部分では撮像倍率（欠陥抽出倍率、欠陥観察倍率）を低く設定する必要がある。よって、被対象基板上の領域毎に画像の撮像倍率を規定し、上記のようなエイリアシングによるノイズパターン発生を防ぐことが可能となる。従って、全体制御部（ホストコンピュータ）２０は、投入される被対象基板１０上に部分領域毎に形成されている回路パターンの種類（空間周波数が高いか低いか）に関する設計情報を、予め、記録媒体等の入力手段２１またはネットワーク２２を用いてＣＡＤシステム（図示せず。）や製造ラインを管理している管理システム（図示せず。）から入力してメモリ部２４または記憶装置２３に記憶しておくことが必要となる。そして、全体制御部（ホストコンピュータ）２０は、予め、この回路パターンの種類に関する設計情報（空間周波数）を基に、被対象基板１０上の領域毎に最低の撮像倍率を求めてメモリ部２４に記憶させておくことによって、投入される被対象基板１０の領域ごとに対する撮像倍率（欠陥抽出倍率、欠陥観察倍率）が適切であるか否かの確認をすることができる。
【００６８】
即ち、全体制御部（ホストコンピュータ）２０は、欠陥検査装置２から検出されて記憶装置２３に記憶された欠陥の位置座標からその領域における最低の撮像倍率をメモリ部２４から引き出すことが可能となる。従って、全体制御部２０は、ステップＳ４０６およびステップＳ４１２、Ｓ４１２ａにおける欠陥寸法に対応する欠陥抽出倍率やステップＳ４０７ｃおよびステップＳ４１２ｄにおける欠陥観察倍率が、欠陥が存在する領域における最低の撮像倍率の条件を満たしているか否かを調べることができ、もし満たさない場合には、図５Ａ、および図５Ｂに示した欠陥サイズによりスキップするステップＳ４０７ｂ、Ｓ４１２ｃと同じステップにて、この欠陥の画像収集をスキップする。このように、全体制御部２０は、欠陥抽出倍率や欠陥観察倍率を、欠陥が存在する領域における最低の撮像倍率を満たして欠陥を撮像することによって欠陥の背景（回路パターン）からのノイズパターン発生を防止して忠実に欠陥を示すデジタル画像信号を取得でき、ずれ補正（アライメント）を正確に行うことができると共に、欠陥の特徴量や性質についての詳細解析の信頼度を向上させることができる。
【００６９】
【発明の効果】
本発明によれば、欠陥検査装置との間に存在する座標系の違いを安定に補正することができるので、欠陥検査装置で検出された微細な欠陥についても短い検索時間で安定に捉えることができ、その結果、欠陥の特徴量（サイズ、形状、表面状態、濃淡値等）や性質（カテゴリー）について詳細解析できる高い撮像倍率（例えば１００００倍以上）で撮像された高分解能を有するデジタル画像信号を取得できる走査型電子顕微鏡による画像自動収集装置およびその方法を実現することができる効果を奏する。
【図面の簡単な説明】
【図１】本発明に係る画像自動収集装置の半導体製造プロセスにける役割を説明するための図である。
【図２】本発明に係る画像自動収集装置の一実施例を示す概略構成図である。
【図３】本発明に係る画像自動収集装置において画像自動収集処理する第１の実施例を示すフローチャート図である。
【図４Ａ】本発明に係る画像自動収集装置において画像自動収集処理する第２の実施例の前半を示すフローチャート図である。
【図４Ｂ】本発明に係る画像自動収集装置において画像自動収集処理する第２の実施例の後半を示すフローチャート図である。
【図５】パラメータ設定例を示す図である。
【図６Ａ】本発明に係る画像自動収集装置において画像自動収集処理する第３の実施例の前半を示すフローチャート図である。
【図６Ｂ】図６Ａに示す第３の実施例の後半を示すフローチャート図である。
【図７】被検査対象を区分的な領域に分割する実施例を示す図である。
【図８Ａ】本発明に係る画像自動収集装置において画像自動収集処理する第４の実施例の前半を示すフローチャート図である。
【図８Ｂ】図８Ａに示す第４の実施例の後半を示すフローチャート図である。
【符号の説明】
１…プローブ検査、２…欠陥検査装置（外観検査装置）、３…画像自動収集装置、４…外観検査結果、５…欠陥画像、６…不良モード別の発生頻度を示す画面、７…品質管理システム、８…搬送装置、１０…被対象基板、１３…画像入力装置（画像入力部）、１４…画像記録装置（画像記憶装置、画像記憶部）、１５…画像処理装置、１６…ステージ制御部、１７…搬送制御部、１８…モニタ、２０…全体制御部（ホストコンピュータ）、２１…キーボード・マウス等の入力手段、２２…ネットワーク、２４…メモリ部、２５…バス、１０１…走査型電子顕微鏡、１１１…電子銃、１１２…収束レンズ（コンデンサレンズ）、１１３…走査偏向器、１１４…対物レンズ、１１５…グランド電極、１１７…リターディング電極、１１８…ステージ、１２０…電子検出器、１２１…アンプ、１３１…Ａ／Ｄ変換器、１３２…前処理回路。[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image automatic collecting apparatus including a scanning electron microscope that automatically collects defect images, and more particularly to a defect including a scanning electron microscope suitable for efficiently reviewing defects in a semiconductor manufacturing process. The present invention relates to an automatic image collection apparatus and method.
[0002]
[Prior art]
Conventionally, a defect image existing on a target substrate such as a semiconductor wafer is imaged at a constant magnification using an optical microscope, and the image is collected. The position of the defect on the semiconductor wafer is the defect to be observed by using the position information of the defect detected by an appearance inspection apparatus such as a pattern inspection apparatus or a foreign substance inspection apparatus and moving the wafer to the position indicated by these coordinates. Was imaged.
By the way, there is a remarkable progress in miniaturization of a wiring pattern in a semiconductor wafer, and the defect size to be observed is sometimes lower than the wavelength of light. For this reason, instead of optical observation, defect observation using an image by an electron microscope has been performed.
[0003]
JP-A-5-223747 (Prior Art 1) is known as a conventional technique for capturing a defect image with such an electron microscope.
This prior art 1 is provided by the above apparatus in an electron microscope for observing or analyzing the shape of a foreign substance or a defect using wafer coordinates and foreign substance information provided by an optical surface foreign substance inspection apparatus and similar apparatuses. A means for determining the level of the size of the foreign material, and when the foreign material level is above a certain level, the foreign material is searched with a reference magnification which is a low magnification, and when the foreign material level is below the certain level, the observation area is divided into N × M An observation apparatus is described that is divided into regions and has means for searching for foreign matter across the observation region at a high magnification for each divided region.
[0004]
[Problems to be solved by the invention]
For example, when collecting defect images of a target substrate such as a semiconductor wafer, the difference in coordinate management method between the appearance inspection apparatus and the scanning electron microscope, the braking error of the individual inspection stage of the appearance inspection apparatus and the scanning electron microscope When the observation object is moved to the position of the defect given by the semiconductor pattern appearance inspection apparatus or the foreign substance inspection apparatus with the scanning electron microscope observation apparatus, the defect as the observation object enters the observation image field of view. If the observation magnification is sufficiently reduced, a defect image can be obtained with an electron microscope. However, since the observation magnification is sufficiently lowered, there is a restriction on the minimum defect size that can be confirmed in the image field, and there is a problem that a minute defect cannot be observed.
Therefore, in the prior art 1, it is necessary to increase the observation magnification so that a fine defect can be observed, and to search for a fine defect over an observation region composed of M × N divided regions. It will be inevitable. In particular, when a large number of minute defects exist on the target substrate, useless searches will increase significantly.
[0005]
An object of the present invention is to solve the above-mentioned problems by positioning a minute defect within a high-magnification imaging field in a short time even in the case of a minute defect, thereby capturing a high-resolution digital image of the minute defect. It is an object of the present invention to provide an automatic image collecting apparatus and method using a scanning electron microscope which can acquire an image signal and analyze its feature amount and its property (category).
[0006]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a stage on which a target substrate is placed, an electron gun that emits an electron beam, a converging lens that converges the electron beam emitted from the electron gun, and the converging lens Scanning means for scanning the surface of the target substrate two-dimensionally on the surface of the target substrate (including scanning by a scanning deflector and scanning by a stage), and the electron beam converged by the focusing lens on the target An objective lens for focusing in a spot shape on the surface of the substrate, a detector for detecting the intensity of electrons generated from the target substrate by scanning the electron beam by the scanning means, and outputting an analog image signal; and An image input unit having an A / D conversion unit that samples and converts an analog image signal detected and output into a digital image signal, and obtained from the image input unit A scanning electron microscope including an image storage unit that stores a digital image signal, and stores information about a dimension and a first position coordinate of a defect present on a target substrate acquired from an appearance inspection apparatus. And a low-magnification obtained by controlling the scanning means for the large defect based on the information on the first position coordinates of the large-sized defect existing on the target substrate obtained from the storage unit. Positioning in the field of view of the imaging magnification, imaging the positioned large defect at a low magnification imaging magnification, storing the digital image signal of the large defect in the image storage unit, and storing the stored digital image signal of the large defect A deviation correction coefficient calculating means for calculating a second position coordinate of the defect based on the relationship and calculating a deviation correction coefficient from the relationship between the calculated second position coordinate and the first position coordinate. Which is the image automatic acquisition apparatus and method characterized by comprising.
[0007]
Further, the present invention is a scanning electron microscope, a storage unit for storing information about a dimension and a first position coordinate of a defect present on a target substrate acquired from an appearance inspection apparatus, and the storage Within the field of view of the first imaging magnification obtained by controlling the scanning means on the basis of the information on the first position coordinates of the defect satisfying a desired dimension existing on the target substrate obtained from the section The defect is positioned at a first imaging magnification, and a digital image signal of the defect is stored in the image storage unit. Based on the stored digital image signal of the defect, the first defect of the defect is stored. And a shift correction coefficient calculating means for calculating a shift correction coefficient from the relationship between the calculated second position coordinate and the first position coordinate. Collector and It is a way.
[0008]
In addition, the present invention provides a scanning electron microscope, a storage unit that stores information on a dimension and a first position coordinate of a defect existing on a target substrate acquired from an appearance inspection apparatus, and the target An area setting means for setting and registering a target substrate by dividing it into a plurality of areas, and a defect satisfying a desired dimension existing in each area on the target substrate set and registered by the area setting means is stored in the storage unit. Based on the information on the first position coordinates of the defect for each region selected from the storage unit, the defect for each region is obtained by controlling the scanning means. Positioning within the field of view of the first imaging magnification, imaging the defect for each positioned region at the first imaging magnification, and storing the digital image signal of the defect for each region in the image storage unit, Digit of the stored defect Second position coordinates of the defect for each area are calculated based on the image signal, and the relationship between the calculated second position coordinates for each area and the first position coordinates for each area is calculated. An automatic image collection apparatus and a method therefor, comprising: a deviation correction coefficient calculating means for calculating a deviation correction coefficient for the entire target substrate.
[0009]
In the image automatic collection apparatus and method thereof, the present invention further includes the shift correction coefficient calculated by the shift correction coefficient calculation means for a defect present on the target substrate obtained from the storage unit. The second position coordinate is calculated by correcting the first position coordinate of the defect obtained from the above, and the defect is obtained by controlling the scanning means based on the information on the calculated second position coordinate. An image acquisition control means for positioning in the field of view of the imaging magnification of 2, imaging the positioned defect at the second imaging magnification, and storing and collecting a digital image signal of the defect in the image storage unit It is characterized by that.
In the image automatic collection apparatus and method thereof, the present invention further includes a deviation correction coefficient calculated by the deviation correction coefficient calculation means for a small-sized defect present on the target substrate obtained from the storage unit. The second position coordinate is calculated by correcting the first position coordinate of the small defect obtained from the storage unit, and the scanning means is controlled for the small defect based on the information on the calculated second position coordinate. The image acquisition is performed by positioning in the field of view of the high magnification imaging magnification obtained in this way, imaging the small defect positioned at a high magnification imaging magnification, and storing and collecting the digital image signal of the small defect in the image storage unit Control means is provided.
[0010]
In the image automatic collection apparatus and method thereof, the present invention further includes a deviation correction coefficient calculated by the deviation correction coefficient calculation means for a small-sized defect present on the target substrate obtained from the storage unit. The second position coordinate is calculated by correcting the first position coordinate of the small defect obtained from the storage unit, and the scanning unit is controlled for the small defect based on the information on the calculated second position coordinate. Is positioned in the field of view of the high magnification imaging magnification obtained by this, and the positioned small defect is imaged at a high magnification imaging magnification, and the digital image signal of the small defect is stored in the image storage unit, The third position coordinate of the defect is calculated based on the digital image signal of the small defect, and the small defect is imaged at a desired high magnification based on the information on the calculated third position coordinate. Provided with an image acquisition control means for imaging a small defect positioned at a desired high magnification and storing and collecting a digital image signal of the small defect in the image storage unit. It is characterized by that.
[0011]
In the image automatic collection apparatus and method thereof, the present invention further includes a deviation correction coefficient calculated by the deviation correction coefficient calculation means for a small-sized defect present on the target substrate obtained from the storage unit. The second position coordinate is calculated by correcting the first position coordinate of the small defect obtained from the storage unit, and the scanning unit is controlled for the small defect based on the information on the calculated second position coordinate. Is positioned within the field of view of the high magnification imaging magnification obtained by this, and the positioned small defect is imaged at a high magnification imaging magnification, and a digital image signal of the small defect is stored in the image storage unit, and the storage The third position coordinate of the defect and the size of the defect are calculated based on the digital image signal of the small defect, and the small position is calculated based on the information about the calculated third position coordinate. A defect is positioned in the field of view of a high magnification imaging magnification that matches the size of the defect, and the small defect that is positioned is imaged with the imaging magnification of the high magnification that fits, and a digital image signal of the small defect is stored as an image An image collection control means for storing and collecting in the unit is provided.
[0012]
In the image automatic collection apparatus and method therefor, the present invention further includes an observation in which an observation order is set and registered in accordance with a criterion that a movement distance is reduced for a plurality of defects existing on a target substrate obtained from the storage unit. First setting of each defect obtained from the storage unit with a deviation correction coefficient calculated by the deviation correction coefficient calculation unit for each of a plurality of defects existing on the target substrate obtained from the storage unit obtained from the order setting unit The second position coordinates of each defect are calculated by correcting the position coordinates, and each defect is determined according to the observation order set by the observation order setting means based on the information on the calculated second position coordinates of each defect. Is positioned within the field of view of the second imaging magnification obtained by controlling the scanning means, each of the positioned defects is imaged at the second imaging magnification, and a digital image signal of the defect is obtained as the image. Characterized by comprising an image collection control means for collecting stored in 憶部.
The present invention is also directed to the automatic image collection apparatus and method thereof, further comprising an offset value calculating means for calculating an offset value, and the deviation correction coefficient calculating means for a defect present on the target substrate obtained from the storage unit. The first position coordinate of each defect obtained from the storage unit is corrected with the offset correction coefficient calculated in step 1 and the offset value calculated by the offset value calculation means to calculate a second position coordinate of the defect, Based on the information on the calculated second position coordinates of the defect, the defect is positioned within the field of view of the second imaging magnification obtained by controlling the scanning means, and the positioned defect is second imaging magnification. And image acquisition control means for storing and collecting digital image signals of the defects in the image storage unit.
[0013]
Further, the present invention is a scanning electron microscope, a storage unit for storing information about a dimension and a first position coordinate of a defect present on a target substrate acquired from an appearance inspection apparatus, and the storage The large defect is positioned in the field of view of the low magnification imaging magnification obtained by controlling the scanning means on the basis of the information on the first position coordinate regarding the large-sized defect existing on the target substrate obtained from the section. The positioned large defect is imaged at a low magnification, and a digital image signal of the large defect is stored in the image storage unit, and the second of the defect is stored based on the stored digital image signal of the large defect. And the size of the defect are calculated, a deviation correction coefficient is calculated from the relationship between the calculated second position coordinate and the first position coordinate, and further, the calculated second position coordinate is calculated. And positioning the image within the field of view of the imaging magnification suitable for the calculated size of the defect, imaging the positioned large defect with the imaging magnification suitable for the image, and storing a digital image signal of the large defect in the image storage unit The first image acquisition control means for storing and collecting, and the storage with the deviation correction coefficient calculated by the first image acquisition control means for a small-sized defect present on the target substrate obtained from the storage section. The first position coordinate of the small defect obtained from the portion is corrected to calculate the second position coordinate, and the small defect is obtained by controlling the scanning unit based on the information on the calculated second position coordinate. The image is positioned in the field of view of the high magnification imaging magnification, the small defect positioned is imaged at a high magnification imaging magnification, and a digital image signal of the small defect is stored in the image storage unit and collected. An image automatic acquisition apparatus and method is characterized in that an image collection control unit.
[0014]
In addition, the present invention is a scanning electron microscope, and a storage unit that stores information on dimensions and position coordinates of a defect existing on a target substrate, and information on a circuit pattern in a region on the target substrate; Restriction limited based on information on a circuit pattern in an area where the defect exists based on information on a position coordinate of a defect to be imaged obtained from the storage unit, and on the basis of information on the acquired circuit pattern An imaging magnification is calculated, an imaging magnification of the defect to be imaged is determined based on information about the size of the defect to be imaged obtained from the storage unit, and the determined imaging magnification is the calculated limited imaging magnification A control unit that controls the scanning unit so as to capture the defect to be imaged at the determined imaging magnification. In part, an image automatic collecting device, characterized by being configured to collect and store the digital image signals captured by the imaging magnification adapted to the dimensions of the defect.
Further, the present invention is a scanning electron microscope, wherein a storage unit that stores information relating to a correlation between a model or type of an appearance inspection apparatus and an imaging magnification, and a target substrate that is input to the scanning electron microscope An input means for inputting information relating to the type or type of the appearance inspection apparatus that has been inspected for existing defects, and the information stored in the storage unit based on the information relating to the type or type of the appearance inspection apparatus input by the input means. And a control unit that controls the scanning unit to determine the imaging magnification based on the information related to the correlation and to image the defect existing on the target substrate with the determined imaging magnification. Automatic collection device.
[0015]
In the image automatic collection apparatus and method thereof, the present invention further calculates a defect feature amount from a defect digital image signal collected and stored in the image storage unit, and the calculated feature amount is calculated. An analysis means for classifying the nature of the defect by analyzing is provided.
In addition, the present invention inputs information on the dimensions of each defect together with defect coordinate information from the appearance inspection apparatus to the scanning electron microscope, and whether or not the defect position can be recognized in the image in the scanning electron microscope Therefore, an observation image magnification that is inversely proportional to the defect size is set continuously or stepwise, and the observation magnification is changed in accordance with the defect size to capture a defect image. At the time of inputting the defect image, the deviation of the coordinate system between the appearance inspection apparatus and the scanning electron microscope is extracted by using at least two defects having the first large defect size, and the subsequent defect position information is corrected. As a result, it is possible to realize an automatic image collecting apparatus that can stably detect a defect position in an image by inputting an image at an optimum magnification according to the size of the defect, and can reliably input an image for defect observation. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a diagram for explaining a role played by a defect image automatic collecting apparatus according to the present invention in a semiconductor manufacturing process.
A semiconductor manufacturing process may be manufactured through several hundred processes 1 to n (P1 to Pn) and may take a period of about 100 days to complete. However, it is the probe inspection 1 in which all processes are completed to determine the quality of the product. For this reason, in order to improve the yield, means for estimating the quality of the process on the way is essential. For this purpose, the defect inspection apparatus 2 composed of an optical pattern defect inspection apparatus or a foreign substance defect inspection apparatus performs an appearance inspection of the substrate to be inspected (wafer substrate), and processes from abnormal appearance such as wiring pattern defects and foreign substance defects. It is performed to determine whether the quality is good or bad. When a process abnormality is confirmed, it is necessary to take countermeasures. However, the defect image automatic collection apparatus 3 plays an important role as information collection means for this purpose.
[0017]
That is, the progress of miniaturization of the wiring pattern in a semiconductor wafer or the like is remarkable, and the defect size to be detected tends to be miniaturized to 0.2 μm or less, and therefore, the appearance to be inspected by the optical defect inspection apparatus 2 Although the location and number of defects can be grasped from the inspection result 4, information such as the nature of the defect cannot be obtained. Therefore, based on the defect location (positional coordinates) on the substrate to be inspected obtained as a result 4 of the visual inspection, the defect image automatic collection device 3 uses the feature amount (the size and shape of the defect portion) of the image 5 of the defect occurrence portion. The defect nature (category) is classified and output by referring to the teaching data on the basis of the surface condition, gray value, etc., and the defect management system 3 detects the defect classified by the automatic defect image collection device 3 in the quality control system 7. Based on the nature (categorie), it is possible to narrow down the countermeasure candidates by confirming whether the defect is a fatal defect in the process. The example shown in 6 of FIG. 1 shows a result of reorganizing the result of classifying the defect images for each defect type (category). In FIG. 6, the defect types are schematically shown as two types: pattern defects and foreign object defects. According to the result 6 obtained from the defect image classification device 3, it can be seen that the quality control system 7 has a higher occurrence frequency of foreign matters than pattern defects, and therefore it is sufficient to take measures to prevent foreign matters. That is, in the quality management system 7, it is possible to quickly improve the yield by preferentially estimating and taking the cause of defects with high occurrence frequency.
[0018]
The automatic image collecting apparatus 3 according to the present invention automatically collects defect image for review for the purpose of improving the efficiency of defect review work review work that has been performed visually, that is, stably defects. An image collection function that can be supplemented is realized.
[0019]
Next, the configuration of the automatic image collecting apparatus 3 constituted by the scanning electron microscope according to the present invention will be described with reference to FIG. The overall control unit (host computer) 20 controls the transfer apparatus 8 via the transfer control unit 17, and moves the target substrate (for example, wafer substrate) 10 to a stage 118 that can move (run) in the XY axis direction. Mount. On the other hand, information specifying the target substrate 10 input from the wafer ID reading device provided in the transfer device 8 or input by the user via the keyboard 21 or the like is obtained, and defect coordinate information corresponding to this is obtained from the network 22. The host computer 20 receives from the host system via This defect coordinate information is used for defect review or defect image collection from all the defect coordinate points output from the defect inspection apparatus (appearance inspection apparatus) 2 shown in FIG. This relates to the narrowed-down defect coordinate points. The host system refers to a quality management system such as a yield management system, a production line monitoring system, a process management system, or an inspection apparatus for inspecting defects. The host computer 20 refers to the defect coordinate information, sends an instruction to the stage control unit 16, moves the stage 118, and moves the defect to the observation position. The defect is imaged by the electronic detector 120, and the defect image is recorded in the image recording device (image storage device) 14 via the image input device 13. The above processing is repeated for the designated defect, and the defect image captured for the defective portion existing on the target substrate 10 is accumulated in the image recording device 14. The overall control unit (host computer) 20 also directly or directly manufactures information about the model name and type name of the defect inspection apparatus inspecting the target substrate to be input to the image automatic collection apparatus 3 from the appearance inspection apparatus 2. The data is input from a management system or the like that manages the entire line via the input means 21 such as a recording medium or the network 22 and stored in the storage device 23. Therefore, the overall control unit (host computer) 20 can also grasp information about which defect inspection apparatus has been inspected for the substrate to be loaded.
[0020]
In the case of the scanning electron microscope 101, an electron beam image can be acquired as a high-definition appearance image having a high resolution. The scanning electron microscope 101 includes a detection unit 110 and an image input unit 13. The electron optical system in the detection unit 110 includes an electron gun 111, an electron beam extraction electrode (not shown), a condenser lens (converging lens) 112, a blanking deflector (not shown), a diaphragm (not shown), scanning. It comprises a deflector 113, an objective lens 114, a reflector (not shown) that reflects detected electrons, an ExB deflector (not shown), and a Faraday cup (not shown) that detects a beam current. The reflector was conical and had a secondary electron multiplication effect. Among the electron detectors, for example, an electron detector 120 that detects electrons such as secondary electrons, reflected electrons, and absorbed electrons is disposed above or below the objective lens 114, for example. The output signal of the electron detector 120 is amplified by the amplifier 121.
[0021]
In the sample chamber, a sample stage 123 on which a target substrate (teaching substrate) 10 for acquiring a high-definition appearance image having high resolution is placed, and the sample stage 123 is moved in the XY axis direction. A stage 118, a position monitor length measuring device (not shown) for measuring the position of the stage, and a height measuring device (not shown) for measuring the height for measuring the height of the target substrate 10. Is installed. The position monitor length measuring device measures the position of the stage 118 and the like, and transfers the result to the overall control unit 20. Therefore, the overall control unit 20 can accurately grasp the region and position where the electron beam 122 is irradiated based on these data. Furthermore, in the storage device 23, a target substrate (existing various defects such as a foreign matter inspected by an optical defect inspection device (foreign matter inspection device or pattern inspection device) 2 or a defect in a wiring pattern (circuit pattern)) ( Information on the approximate position coordinates of the defect (including the approximate position data (xn, yn)), the number of defects, and information on each defect size is stored. Therefore, when the target substrate 10 on which various defects such as a foreign substance inspected by the optical defect inspection apparatus 2 and a defect of the wiring pattern exist is placed on the stage 118, the overall control unit 20 displays the storage device 23. A wide area (wide field of view) to which the electron beam 122 is irradiated by controlling the stage 118 based on the approximate position data of the defect stored in the stage 118 and the position coordinates of the stage 118 and the like measured by the position monitor length measuring device. Defects can be positioned within.
[0022]
The height measuring instrument measures the height of the target substrate 10 placed on the stage 118 using an optical measuring instrument or the like. Then, based on the height data measured by the height measuring device, the focal length of the objective lens 114 for narrowing the electron beam is dynamically corrected, and the electron beam is always irradiated with the focus in the observation region. It can be done.
The electron beam exiting the electron gun 111 passes through the condenser lens 112 and the objective lens 114, and is narrowed to a beam diameter of about the pixel size on the sample surface. At this time, a negative potential is applied to the target substrate 10 by the ground electrode 115 and the retarding electrode 117, and the electron beam is decelerated between the objective lens 114 and the target substrate 10. Increase resolution. When the electron beam 122 is irradiated, electrons are generated from the target substrate 10. By detecting the electrons generated from the target substrate in synchronization with the repeated scanning of the electron beam 122 in the X direction by the scanning deflector 113 and the continuous movement of the target substrate 10 in the Y direction by the stage 118, A two-dimensional high-definition electron beam image of the substrate is obtained. Electrons generated from the target substrate are captured by the electron detector 120 and amplified by the amplifier 121. Here, as the scanning deflector 113, an electrostatic deflector having a high deflection speed may be used. As the electron gun 111, it is preferable to use a thermal field emission electron gun that can increase the electron beam current and shorten the irradiation time. The electron detector 120 may be a semiconductor detector that can be driven at high speed.
[0023]
The image input unit 30 is mainly configured by an A / D converter 131 and a preprocessing circuit 132. The electron detection signal detected by the electron detector 120 is amplified by the amplifier 121 and converted into digital image data (gradation image data) by the A / D converter 131. The converted digital image data is transmitted by, for example, a transmission means (optical fiber cable) and input to the preprocessing circuit 132. In the pre-processing circuit 132, dark level correction, electron beam fluctuation correction, shading correction, and the like are performed, and further, a filtering process for eliminating the pseudo noise component is performed to improve the image quality.
As described above, in the scanning electron microscope 101, the target substrate (teaching substrate) 10 obtained from various manufacturing processes and having various micro defects having different dimensions (sizes) and states exists on the stage 118. By mounting on the substrate, the micro defect is positioned in a wide area (wide field of view) irradiated with the electron beam 122, and a high-definition appearance image based on the electron beam image of the defect is acquired by the electron detector 120 and the amplifier 121. Then, the data is input to the image input unit 13 and stored in the image storage device 14 via the bus 25.
[0024]
As described above, if the relationship between the stage coordinate system and the target substrate coordinate system of the defect inspection apparatus 2 and the image automatic collection apparatus 3 is exactly the same, the same alignment mark on the target substrate (wafer substrate) 10 is displayed. Using the defect coordinate value output from the defect inspection apparatus 2 for the defect to be observed by using the target on the target substrate and acquiring the image of the corresponding defect with the image automatic collecting apparatus 3 No problem arises. However, in reality, it is difficult to share defect coordinates between the defect inspection apparatus 2 and the automatic image collection apparatus 3. The reason for this is the difference in the relationship between the stage coordinate system in each apparatus and the coordinate system on the target substrate, the stage braking error in each apparatus, and the like. In addition, there is a problem that there is no alignment mark on the target substrate on which no pattern is formed, such as a face plate.
When there is no common alignment mark, or when there is a deviation in coordinates between the defect inspection apparatus 2 and the automatic image collection apparatus 3, a method for performing alignment using a defect present on an observation target is disclosed in Japanese Patent Application Laid-Open No. Hei 6 (1994). -249790.
[0025]
By the way, in order to image the defect by moving the stage 118 to the position of the designated defect in a state where the alignment is not accurately performed, the imaging magnification is lowered, the wide range is imaged, and the defect is captured in the image. There must be. However, it is difficult to detect minute defects at a low magnification. Therefore, when a defect is used for alignment, if a defect having a large defect size is preferentially used, it can be reliably detected even at a low magnification. Therefore, the overall control unit (host computer) 20 is acquired from the defect inspection apparatus 2 and input, for example, via the network 22 or input by the input means 21 such as a recording medium and stored in the storage device 23. The information is rearranged in order of size according to the size of each defect, and the defect is imaged by the electron detector 120 in accordance with the rearranged order, input to the image input unit 13, and converted into a digital image signal by the image input unit 13. Further, if a defect image is acquired by performing dark level correction, electron beam fluctuation correction, shading correction, etc., and further performing filtering processing to eliminate the pseudo noise component and storing it in the image storage device 14, Since defects can be detected even when images are taken at low magnification, defects are used for alignment purposes. Rukoto becomes possible, because after completion of the alignment is improved positioning accuracy of the stage 118 of the defect, acquired defect image can be at a higher magnification. That is, it is possible to acquire a defect image at an appropriate magnification even for a minute defect.
[0026]
Next, an operation flow in which the automatic image acquisition device 3 acquires a defect image at a higher magnification based on the defect position coordinates acquired from the defect inspection device 2, the number of defects on the target substrate, and the size of the defect. The first embodiment will be described with reference to FIG.
First, in step S401, the defect on the target substrate used for alignment by converting the defect position coordinates acquired from the defect inspection apparatus 2 into the coordinate system of the image automatic collection apparatus 3 is stored in the memory unit 24 such as a ROM. And the imaging magnification (defect extraction magnification with respect to the defect size) for extracting a defect based on the defect size acquired from the defect inspection apparatus 2 is input in advance using the input means 21 and the ROM or the like. It is stored in the memory unit 24 and set. That is, the number N of defects on the target substrate used for alignment in the memory unit 24 such as a ROM (as long as alignment can be performed in the coordinate system of the image automatic collection device 3, N is about 5 to 10). And the imaging magnification (defect extraction magnification with respect to the defect size) for extracting the defect based on the defect size acquired from the defect inspection apparatus 2 may be prepared as a table. In addition, as the data regarding the defect extraction magnification with respect to the defect size set in the memory unit 24 such as the ROM in advance, the defect size acquired from the defect inspection apparatus 2 is classified according to the size, and for each class, A method of defining the imaging magnification and a method of setting the imaging magnification so that the defect size of the image falls within a certain size or a certain size range are conceivable.
[0027]
The former is classified into class α, for example, a defect of less than 0.5 μm, class β, for example, a defect of 0.5 μm or more and less than 1 μm, class γ, for example, a defect of 1 μm or more and less than 5 μm, and class δ, a defect of 5 μm or more. For each class, class α is 50000 times (for example, a 0.1 μm defect is imaged as a 5 mm digital image signal), and class β is 30000 times (for example, a 0.5 μm defect is a 15 mm digital image signal). Class γ is imaged 10,000 times (for example, a 1 μm defect is imaged as a 10 mm digital image signal), and class δ is imaged 3000 times (for example, a 5 μm defect is imaged as a 15 mm digital image signal). This is a method of assigning the imaging magnification. In addition, it is possible to set that an imaging magnification is not assigned to a specific class and that a defect corresponding to this class is not imaged. For example, in the above example, class δ is set to 5 μm or more and less than 10 μm, for example, class E is provided for a defect of 10 μm or more, and a defect corresponding to class E (for example, when the magnification is 3000 times, a 10 μm defect is imaged at 30 mm. ) Will not take an image. As a result, it is possible to prohibit image acquisition for a defect having a very large size and protruding from the image field of view. As described above, there is a scanning electron microscope that can obtain an imaging magnification of about 3000 times to 50000 times.
[0028]
In the latter, the size of the defect observed on the image is designated in advance by the image size (unit: pixel). For example, assuming that the pixel resolution is Y μm in an image with a magnification of X, and the defect size (unit: pixel) in the image is designated as a Z pixel, the imaging magnification D for imaging a defect with a dimension of C μm is D = (C × X) / (Y × Z). The same applies if the ratio is specified for the image. In addition, when a certain width is allowed for the designated value of the defect size on the image, a certain width is also permitted for the imaging magnification. Therefore, an appropriate magnification within the permitted range may be selected.
Next, in step S402, the defect position coordinates and the defect dimension information about the number M of defects on the target substrate 10 input from the defect inspection apparatus 2 to the image automatic collection apparatus 3 are the network 22 or the recording medium. Are input and stored in the storage device 23.
Next, in step S <b> 403, the overall control unit (host computer) 20 uses the defect size information about the number M of defects on the target substrate 10 to be input to the image automatic collection device 3 stored and accumulated in the storage device 23. Based on the order of increasing defect dimensions, the rearranged order is registered in the storage device 23 as the image collection order n in the automatic image collection device 3. Since the number of defects on the target substrate 10 put into the image automatic collecting apparatus 3 is M, the number of defects to be imaged by the image automatic collecting apparatus 3 is M.
[0029]
Then, the target substrate 10 is loaded onto the stage 118 by the transfer device 8.
[0030]
Next, in step S <b> 404, the overall control unit (host computer) 20 determines the image collection order as the descending order of the defect size on the target substrate 10 that is input to the image automatic collection device 3 stored and accumulated in the storage device 23. Specify n = 1 as n.
[0031]
Next, in step S <b> 405, the overall control unit (host computer) 20 drives and controls the stage control unit 16 based on the position coordinates of the defects from the largest n = 1 in the defect size stored in the storage device 23. Accordingly, the stage 118 on which the target substrate 10 is placed is moved so that the defect n located at (Xn, Yn) on the target substrate can be imaged by the electron detector 120, and the defect n is positioned on the optical axis. .
Next, in step S <b> 406, the overall control unit (host computer) 20 sets the defect extraction magnification corresponding to the defect size in the memory unit 24 from the order of the largest defect size n = 1 stored in the storage device 23. The amount of scanning deflection is selected from the table and switched to a low magnification detection system (120 or the like) so as to obtain the selected magnification, or the scanning deflector 113 or the like (the scanning of the stage 118 may be combined). Is controlled to obtain a low magnification, and an image of the defect is taken at a low magnification. A defect having such a large size can be positioned in the imaging field of low magnification, and the position coordinates (Xn, Yn) of the defect can be detected by the coordinate system of the image automatic collection device 3. It becomes. In the case of the scanning electron microscope 101, the sampling period for digital conversion in the A / D converter 131 is constant during both low magnification imaging and high magnification imaging. As described above, when the sampling cycle is constant, the sampling interval is widened at a low magnification, and the resolution is lower than that at a high magnification. However, since the imaging magnification is determined according to the defect size, the same resolution can be obtained for the defect size. However, it is also possible to change the sampling period according to the imaging magnification.
[0032]
That is, in step S406, the overall control unit (host computer) 20 determines from the first largest one set in the memory unit 24 to the defect having the Nth (N = about 5 to 10) defect size. By controlling the amount of scanning deflection by the scanning deflector 113 or the like (the scanning of the stage 118 may be combined) so as to capture an image with an imaging magnification corresponding to the defect size, the electron detector 120 starts from the first largest one. Up to a defect having the Nth defect size is imaged at a defect extraction magnification corresponding to the defect size, input to the image input unit 13, converted into a digital image signal at the image input unit 13, and further subjected to dark level correction, electronic Perform line fluctuation correction, shading correction, etc., and filter processing to eliminate pseudo noise components It will be stored in 憶 device 14. As described above, since the imaging from the largest to the Nth defect is performed in the coordinate system of the automatic image collection device 3, the alignment in the coordinate system of the automatic image collection device 3 is also provided. The imaging magnification at this time is a fixed magnification or variable magnification which is a low magnification set and stored in the memory unit 24 in order to capture an alignment defect image (obtained by controlling the scanning deflector 113 and the like). May be used.
[0033]
Next, in step S407, on the basis of a command from the overall control unit (host computer) 20, for example, an image at the same location of an adjacent chip is used as a reference image, and the first largest set in the memory unit 24 is determined as N Up to the defect having the second defect size is imaged at the defect extraction magnification corresponding to the defect size, input to the image input device 13, and stored in the image recording device (image storage device) 14. As a result, the image processing device 15 extracts the difference image indicating the defect between the defect image from the largest one stored in the image recording device 14 to the defect having the Nth defect size and the reference image, and this extracted image is extracted. The difference image indicating the defect is converted into, for example, a binary image signal, and the center of gravity position or the center position in the X direction and the Y direction is calculated from the binary image signal indicating the converted defect in the image. The position of the defect is detected and transmitted to the overall control unit (host computer) 20. The overall control unit (host computer) 20 is based on the position data of the defect in the image detected from the image processing device 15, and a reference coordinate system (target object) such as a stage 118 measured by the position monitor length measuring device. It is also a reference coordinate system on the target substrate 10 because the substrate 10 is positioned and placed on the stage 118.) to obtain defect position coordinates (Xn, Yn) on the target substrate, It can be stored in the storage device 23. At this time, the overall control unit (host computer) 20 performs control so that an image of a representative alignment mark formed on the target substrate 10 is captured at a low magnification similarly to the above, and the center of the alignment mark By calculating the position by the image processing device 15, the defect position coordinates (Xn, Yn) can be obtained based on the alignment mark and stored in the storage device 23.
[0034]
In step S409, the overall control unit (host computer) 20 issues a command to repeat the above-described processing until n reaches N (about 5 to 10) set in the memory unit 24, and N sets of sets are issued. A coordinate pair [(xn, yn), (Xn, Yn)] is obtained. (Xn, yn) is the position of the defect detected in the coordinate system of the defect inspection apparatus (appearance inspection apparatus) 2, and (Xn, Yn) is the position of the defect detected in the coordinate system of the automatic image collection apparatus 3, The difference between the two coordinates is a shift in the coordinate system between the defect inspection apparatus 2 and the automatic image collection apparatus 3. Therefore, the overall control unit (host computer) 20 derives a relational expression between the two coordinate systems using N sets of coordinate pairs, and determines the position coordinates of the defect inspection apparatus 2 as the position coordinates of the image automatic collection apparatus 3. Can be converted to Since there is a difference between rotation and offset between the two coordinate systems, the conversion equation (xn, yn) → (Xn, Yn) is expressed by the following equation (Equation 1).
[0035]
[Expression 1]

[0036]
Therefore, the overall control unit (host computer) 20 can obtain A, B, C, and D from N sets of coordinate pairs [(xn, yn), (Xn, Yn)]. As a calculation method, after obtaining offsets [C, D] from the respective barycentric positions of (xn, yn) and (Xn, Yn), A and B may be obtained by a least square method using a pseudo inverse matrix. . As described above, the overall control unit (host computer) 20 calculates the position coordinates (xn) of the defect inspection apparatus 2 for calculating the position coordinates (Xn, Yn) of the image automatic collection apparatus 3 based on the equation (1). , Yn) can be calculated with respect to deviation correction coefficients [A, B, C, D].
Next, in step S410, the overall control unit (host computer) 20 sets the defect position coordinates obtained from the defect inspection apparatus 2 stored in the storage device 23 for the defects that are sequentially reduced from n = N + 1 to the Mth. The displacement position correction (Xn, Yn) on the target substrate 10 in the coordinate system of the image automatic collection device 3 is performed by correcting the deviation using (Xn, yn) using the conversion formula shown in the above equation (1). Is calculated.
[0037]
Next, in step S411, the overall control unit (host computer) 20 controls the stage control unit 16 by controlling the stage control unit 16 according to the image collection order for n = N + 1 to Mth successively decreasing defects n. It is moved and positioned (alignment) on the optical axis so that the defect n can be imaged by the electron detector 120. Next, in step S412, the overall control unit (host computer) 20 captures the imaging magnification corresponding to the size of the defect n stored in the storage device 23 from the correlation table between the defect size stored in the memory unit 24 and the imaging magnification. The scanning deflection amount by the scanning deflector 113 or the like (which may be combined with the scanning of the stage 118) is controlled so that an image can be captured at the selected imaging magnification, and the image of the defect n is a defect corresponding to the size. The image is picked up by the electron detector 120 at the extraction magnification, and the picked up defect image signal is input to the image input unit 13, converted into a digital defect image signal by the image input unit 13, and further subjected to various corrections and noise removal. It is stored in the image storage device 14. That is, the defect n, which becomes smaller in order from n = N + 1 to the Mth, existing on the target substrate 10 due to the shift correction in the coordinate system of the automatic image acquisition device 3, is obtained by the field of view of the imaging magnification corresponding to the size. It is possible to position (align) the inside of the image, and it is possible to capture an image of the defect n at an imaging magnification corresponding to the size.
[0038]
Next, in step S413, the next defect (n = n + 1) is designated in accordance with the image collection order, and when the image input for all the defects existing on the target substrate is completed in step S414, the target is detected in step S415. The substrate 10 is unloaded from the stage 118 by the transfer device 8, and the process proceeds to defect imaging of the next target substrate.
[0039]
In the above description, it is described that imaging is performed at the defect extraction magnification corresponding to the defect size (defect size) based on the correlation table between the defect size stored in the memory unit 24 and the imaging magnification. The fixed first imaging magnification is used at the time of defect imaging for alignment up to the above, and the fixed second imaging magnification is used for the n = N + 1 to Mth defects. At this time, using the defect imaged at the first imaging magnification for alignment as described above, it becomes possible to perform more detailed positional deviation correction, and the defect positioning accuracy (alignment accuracy) at the time of imaging the N + 1th and subsequent defects. As a result, the variation from the center of the image field of the defect after positioning is reduced, and the second imaging magnification is picked up with a field of view narrower than the field of view obtained with the first imaging magnification, that is, with a high magnification. It becomes possible to do. That is, the second imaging magnification can be set to a higher magnification than the first imaging magnification. In this way, by setting the second imaging magnification to a higher magnification than the first imaging magnification, it becomes possible to capture even finer defects with high resolution on the image, and feature quantities of finer defects ( The size, shape, surface state, gray value, etc.) can be accurately extracted, and the nature (category) of the defect can be analyzed in detail and classified. In particular, the second imaging magnification can be imaged as a digital image signal at a magnification as high as possible (for example, 50000 times (0.02 μm can be taken as a digital image signal with 1 mm) to 30000 times (0.02 μm as 0.6 mm). ), More than that), the feature quantity of the defect can be extracted more accurately, and the property (category) of the defect can be analyzed and classified in more detail.
In the above specific example, the case where the imaging magnification is switched in two stages according to the purpose of defect imaging has been described. However, as described above, classification is performed according to the defect size (defect size), and imaging is performed according to the class of the defect size. The magnification may be determined. Further, a method of applying an imaging magnification for imaging the size of the defect observed on the image with a predesignated image size (unit: pixel) may be used.
[0040]
Next, an operation flow in which the automatic image acquisition device 3 acquires a defect image at a higher magnification based on the defect position coordinates acquired from the defect inspection device 2, the number of defects on the target substrate, and the size of the defect. The second embodiment will be described with reference to FIGS. 4A and 4B.
Next, the difference between the second embodiment and the first embodiment shown in FIG. 3 will be described.
First, in step S401 ′, in addition to the content of step S401, the defect observation magnification corresponding to the defect size calculated in the image processing apparatus 15 is input and set using the input means 21 or the like, and the memory is set. This is a point stored in the unit 24 as a table. The defect extraction magnification is 10,000 times or less so that a large defect can be positioned in the imaging field in consideration of an error between the coordinate system of the defect inspection apparatus 2 and the coordinate system of the image automatic collection apparatus 3 for a large-size defect. The position of the defect detected by the defect inspection apparatus 2 is corrected for an error between the coordinate system of the defect inspection apparatus 2 and the coordinate system of the image automatic collection apparatus 3 for a defect having a size smaller than the above-described defect. Since the data (xn, yn) also includes a detection error, it must be determined to be about 30000 times lower than 50000 times so that the defect having the small size can be positioned in the imaging field of view. However, the defect position (Xn, Yn) is detected in the coordinate system of the automatic image acquisition device 3, and the defect is imaged by repositioning (realigning) the defect to the center (optical axis) of the imaging field. It is possible to obtain a defect image having a higher resolution by increasing the defect observation magnification higher than the defect extraction magnification to correspond to the defect size.
[0041]
Second, in step S407a, the image processing device 15 calculates a difference image signal indicating a defect between the defect image signal obtained in step S406 and the reference image signal, and the defect is calculated from the calculated difference image signal. The position (Xn, Yn) is detected, and the defect size calculated by the area, the length in the X, Y direction, etc. is detected from the binarized image signal indicating the defect.
Third, in step S407b, if the defect size detected in step S407a is larger than the size specified by HUGE I, this defect is not taken as an image collection target, and the next defect is skipped in order. This is because, for example, when the defect size is large, for example, when the imaging field of view protrudes, accurate alignment cannot be expected.
Fourth, in step S407c, the position (Xn, Yn) of the defect detected in step S407a is repositioned at the center of the field of view, and the image is picked up at the defect observation magnification according to the detected defect size again. A defect image signal is input to the image input unit 13, and various corrections and noise component elimination processes are performed and stored in the image storage device 14 to obtain a digital image signal of a large defect. As a result, a digital image signal of a large defect can be captured at a high resolution with a defect observation magnification of about 10,000 times higher than the defect extraction magnification, so that a large defect is also characterized in the overall control unit (host computer) 20. It becomes possible to classify by classifying the quantity and the nature of the defect in detail.
[0042]
Fifth, in step S412a, a defect image signal and a reference image signal are detected by imaging a defect smaller than N defects obtained from the defect inspection apparatus 2 at a defect extraction magnification corresponding to the dimension of the defect number n. The image data is input to the image input unit 13, and various corrections and noise component elimination processes are performed and stored in the image storage device 14 to obtain a defective image signal and a reference image signal.
Sixth, in step S412b, the image processing device 15 calculates a difference image signal indicating a defect between the defect image signal acquired in step S412a and the reference image signal, and the defect is calculated from the calculated difference image signal. The position (Xn ′, Yn ′) is detected, and the defect size calculated by the area, the length in the X, Y direction, etc. is detected from the binarized image signal indicating the defect.
Seventh, in step S412c, when the defect size detected in step S412b is larger than the size specified in HUGE II, this defect is not an image acquisition target, and the next defect is skipped in order. This is a process that assumes a case where a defect of a certain size or more does not need to be collected and confirmed.
[0043]
Eighth, in step S412d, the position (Xn ′, Yn ′) of the defect detected in step S412b is repositioned at the center of the visual field, and imaged at the defect observation magnification according to the defect size detected again. The defect image signal is input to the image input unit 13, and various corrections and noise component elimination processes are performed and stored in the image storage device 14 to obtain an image signal of a large defect. As described above, it is possible to obtain a defect image having a higher resolution by increasing the defect observation magnification corresponding to the defect size for reimaging the defect to be higher than the defect extraction magnification and corresponding to the defect size. As a result, a digital image signal of a small defect can be imaged at a defect observation magnification higher than the defect extraction magnification, for example, about 50,000 times, and acquired with a higher resolution. At 20, it is possible to further classify and classify feature quantities, defect properties, and the like. Except for the first to eighth points described above, the operations and processes are the same as those of the first embodiment shown in FIG.
[0044]
It is possible to update the data relating to the defect size detected by the defect inspection apparatus 2 stored in the storage device 23 with the data relating to the defect size detected in Step S412b and Step S407a. Further, the data related to the defect position detected in step S412 and step S407 is also updated because it is more accurately improved than the data related to the defect position detected by the defect inspection apparatus 2.
4A and 4B are connected by 501 and 502.
Note that steps S410 to S414 shown in FIG. 4B may be executed after the first steps S401 to S409 shown in FIG. 3, and the latter steps S410 to S409 shown in FIG. 3 after steps S101 ′ to S409 shown in FIG. 4A. S414 may be executed.
[0045]
FIG. 5 shows the number N (about 5 to 10) of large defects used for alignment (often about 1 μm to 5 μm as large defects) and the defect extraction magnification (about 3000 to 7000 times) for alignment. Magnification: about 10-30 μm as imaging field of view). This defect extraction magnification is obtained by imaging at a low magnification of about 3000 to 7000 times for a large defect existing on the target substrate 10 based on the position data detected by the defect inspection apparatus 2 in the automatic image collection apparatus 3. It shows that it can be positioned within the visual field (about 10 to 30 μm). That is, the defect extraction magnification indicates the degree of error (about 10 to 25 μm or less) between the coordinate system of the image automatic collection device 3 and the coordinate system of the defect inspection device 2. Since the defect inspection apparatus A has a defect extraction magnification of 3000 times, the position accuracy of the detected defect is the worst, and the defect inspection apparatus C is detected because the defect extraction magnification is 7000 times. It shows that the position accuracy of the defect is the best.
[0046]
As described above, since there is an error between the coordinate system of the automatic image collection device 3 and the coordinate system of the defect inspection device 2, the imaging field of view is set to 10 to be able to position the defect within the imaging field of view. In order to expand to about 30 μm, it is necessary to set the imaging magnification to a low magnification of about 3000 to 7000 times. However, when the imaging magnification is set to a low magnification of about 3000 to 7000 times, the resolution is lowered and it becomes difficult to obtain a digital image signal indicating a defect of about 1 μm or less, for example. Therefore, even when the imaging magnification is set to a low magnification of about 3000 to 7000 times and the resolution is lowered, imaging is performed for a defect (about 1 μm to 5 μm) having a size capable of recognizing the position of the defect from the digital image signal obtained by imaging. As a result, at least the position (Xn, Yn) of the defect can be detected, the deviation correction coefficient [A, B, C, D] based on the above (Equation 1) can be calculated, and the defect extraction magnification can be set. For example, even when the magnification is increased to 10,000 times or more, the defect can be positioned (aligned) in the imaging field, and as a result, a digital image signal having a high resolution based on the high magnification can be obtained for the defect. Is possible.
[0047]
In any case, in the automatic image collection device 3, the imaging field size required for alignment depends on how much the coordinates are shifted in the initial state in relation to the defect inspection device 2, and how much the given coordinates vary. That is, it is necessary to change the imaging magnification (defect extraction magnification) and the number of coordinate points (alignment number) N indicated by a large defect. Since these states depend on the defect inspection apparatus 2 that outputs defect coordinate information, as shown in FIG. 5, the defect extraction magnification and the large defect according to the defect size are determined for each defect inspection apparatus type or for each defect inspection apparatus. The number N of coordinate points shown may be set and stored in the memory unit 24. As described above, the overall control unit (host computer) 20 receives information about which defect inspection apparatus has inspected the target substrate 10 put into the automatic image collection apparatus 3 and stores it in the storage device 23. Therefore, the defect extraction magnification (imaging magnification) in S406 can be controlled for each defect inspection apparatus type or for each defect inspection apparatus.
[0048]
Further, the overall control unit (host computer) 20 obtains the digital image signal obtained by imaging at the defect extraction magnification corresponding to the defect size in step S406 and step S412 and stored in the image storage device 14 with the monitor 18. By displaying the above, it is possible to confirm whether or not the defect extraction magnification and the number of coordinate points N according to the defect inspection device type set or stored in the memory unit 24 or the defect size for each defect inspection device are appropriate. it can. At this time, the overall control unit 20 monitors a table of defect extraction magnification and the number of coordinate points (alignment number) N according to the defect inspection device type or the defect size for each defect inspection device set and stored in the memory unit 24. 18 and can be corrected on the screen of the monitor 18 by using the input means 21.
[0049]
Next, in order to recognize the position of the defect, an optimum defect size D is selected for alignment, and the alignment is performed in consideration of the location of the defect on the target substrate (wafer) 10. A third embodiment of an operation flow for acquiring a defect image at a magnification will be described with reference to FIGS. 6A and 6B. That is, in the third embodiment, the defect coordinate (x) closest to the defect size D for each alignment block (n: n = 1,..., N) in step S504. ⁿ k, y ⁿ k) By selecting (k = 1,..., K), the calculation of the deviation correction coefficients [A, B, C, D] is performed over the entire region without being biased on the target substrate 10. The reason is that the calculation can be made substantially substantially uniformly or uniformly.
First, in step S501, information on which part on the target substrate 10 is selected for the defect on the target substrate 10 used for alignment is set and registered. It is desirable that the alignment defects are arranged substantially uniformly or uniformly without any deviation or unevenness over the entire target substrate 10 (all regions). In order to realize this, as shown in FIG. 7, the target substrate 10 is divided into several blocks, and a predetermined number of alignment defects are selected from one block. This block is hereinafter referred to as an alignment block. An example of the alignment block is shown in FIG. In the example of FIG. 7A, the target substrate 10 is divided into a lattice shape vertically and horizontally, and one section thereof is used as an alignment block. In the example of FIG. 7B, the target substrate 10 is divided by concentric circles and radial lines, and one section is used as an alignment block. A predetermined number of alignment defects are selected from all alignment blocks or a part of alignment blocks.
[0050]
Specifically, the alignment block information, that is, the shape of the alignment block and the section to be used, the number of alignment blocks to be used is N, and the target substrate 10 used for alignment is set to one block. The number K of defects is input in advance using the input means 21, stored in the memory unit 24 such as a RAM, and set and registered. When the area of each divided alignment block is made substantially uniform, the number K of defects set for each alignment block may be made almost uniform. If there is a variation in the area of each divided alignment block, the number K of defects set for each alignment block may be changed accordingly. In short, it is only necessary that the alignment defects can be arranged substantially uniformly or uniformly without any deviation or unevenness over the entire target substrate 10 (all regions).
The setting of the imaging magnification (defect extraction magnification with respect to the defect size) for extracting the defect based on the defect size in step S501 is the same as in the first embodiment.
[0051]
Next, in step S501, the defect dimension D on the target substrate 10 used for alignment is input in advance using the input means 21, stored in the memory unit 24 such as RAM, and registered. Note that the defect dimension data set in advance in the memory unit 24 such as a RAM, according to the definition of the defect dimension acquired from the defect inspection apparatus 2, is one of the projected lengths of X and Y on the detected image, that is, The method of defining by the average of the larger or smaller one or both, the method of defining by the diameter, the dimension in the major axis direction when the ellipse approximation is applied, or the method of defining by the dimension in the minor axis direction, etc. .
Next, in step S502, the defect position coordinates and the defect dimension information for the number M of defects on the target substrate 10 input from the defect inspection apparatus 2 to the image automatic collection apparatus 3 are the network 22 or the recording medium. Are input and stored in the storage device 23.
[0052]
Next, in step S503, the overall control unit (host computer) 20 uses the defect size information on the number M of defects on the target substrate 10 to be input to the image automatic collection device 3 stored and accumulated in the storage device 23. Based on the N alignment blocks specified in step S501, the defects included in each alignment block are rearranged in the descending order of the dimensions. In step 504, the defect having the closest defect size to the specified defect size D is determined. K pieces are selected, and the selected order together with the alignment order k in the alignment block and the k-th defect rating score (x ⁿ k, y ⁿ k) is registered in the storage device 23.
Then, the target substrate 10 is loaded onto the stage 118 by the transfer device 8.
Next, in step S <b> 505, the overall control unit (host computer) 20 performs alignment as an order of alignment using defects on the target substrate 10 that is input to the image automatic collection device 3 stored and accumulated in the storage device 23. The block number n is designated as n = 1, and in step S506, the defect number k as the order of defect alignment in the designated alignment block is designated as k = 1.
[0053]
Next, in step S507, the overall control unit (host computer) 20 performs stage control based on the position coordinates of the defect from the alignment block order n = 1 and the alignment defect order k = 1 stored in the storage device 23. 16 is controlled by driving (x ⁿ k, y ⁿ The stage 118 on which the target substrate 10 is placed is moved so that the defect located at k) can be imaged by the electron detector 120 and the defect is positioned.
Next, in step S508, the overall control unit (host computer) 20 calculates the defect extraction magnification corresponding to the size of the defect from the alignment block order n = 1 and the alignment defect order k = 1 stored in the storage device 23. A table set in the memory unit 24 is selected and switched to a low-magnification detection system (112 or the like) so as to obtain the selected magnification, or scanning deflector 113 or the like (scanning of the stage 118 may be combined). )) Is enlarged so as to obtain a low magnification, and an image of the defect is taken at a low magnification. A defect having such a large size can be positioned in the imaging field of low magnification, and the position coordinates (x ⁿ k, y ⁿ k) can be detected by the coordinate system of the automatic image collection device 3. In the case of the scanning electron microscope 101, the sampling period for digital conversion in the A / D converter 116 is constant during both low magnification imaging and high magnification imaging. As described above, when the sampling cycle is constant, the sampling interval is widened at a low magnification, and the resolution is lower than that at a high magnification. However, since the imaging magnification is determined according to the defect size, the same resolution can be obtained for the defect size. If necessary, the sampling period can be changed according to the imaging magnification.
[0054]
That is, in step S508, the overall control unit (host computer) 20 performs scanning deflection so as to capture an image with an imaging magnification corresponding to the defect size of each of K defects included in the N alignment blocks set in the memory unit 24. By controlling the amount of scanning deflection by the detector 113 or the like (the scanning of the stage 118 may be combined), each of the K defects included in the N alignment blocks by the electron detector 120 corresponds to the defect size. The image is picked up at the defect extraction magnification, input to the image input unit 13, converted into a digital image signal at the image input group 13, and further subjected to dark level correction, electron beam fluctuation correction, shading correction, etc. A filtering process for erasing the components is performed and stored in the image storage device 14. As described above, since imaging of each of K defects included in the N alignment blocks is performed in the coordinate system of the image automatic collection device 3, the alignment in the coordinate system of the image automatic collection device 3 is also provided. . The imaging magnification at this time is a fixed magnification or variable magnification which is a low magnification set and stored in the memory unit 24 in order to capture an alignment defect image (obtained by controlling the scanning deflector 113 and the like). May be used.
[0055]
Next, in step S509, based on a command from the general controller (host computer) 20, for example, an image at the same location of an adjacent chip is included as a reference image in N alignment blocks set in the memory unit 24. Each of the K defects is imaged at a defect extraction magnification corresponding to the defect size, input to the image input device 13, and stored in the image recording device (image storage device) 14. As a result, the image processing device 15 extracts the difference image indicating the defect between the defect image of each of the K defects included in the N alignment blocks stored in the image recording device 14 and the reference image, and this extraction is performed. A difference image indicating a defect is converted into a binary image signal, for example, and the center of gravity position or the center position in the X direction and the Y direction is calculated from the binary image signal indicating the converted defect in the image, for example. The position of the defect is detected and transmitted to the overall control unit (host computer) 20. The overall control group (host computer) 20 is based on the position data of the defect in the image detected from the image processing device 15, and a reference coordinate system (target object) such as the stage 118 measured by the position monitor length measuring device. Since the substrate 10 is positioned and placed on the stage 118, it is also converted into a reference coordinate system on the target substrate 10), and defect position coordinates (X ⁿ k, Y ⁿ k) can be obtained and stored in the storage device 23.
[0056]
The overall control unit (host computer) 20 has been described above until k becomes K set in the memory unit 24 in step S511 and until n becomes N set in the memory unit 24 in step S513. A command is issued to repeat the process, and (N × K) pairs of coordinate pairs [(x ⁿ k, y ⁿ k), (X ⁿ k, Y ⁿ k)]. (X ⁿ k, y ⁿ k) is the position of the defect detected by the coordinate yarn of the defect inspection apparatus (appearance inspection apparatus) 2 (X ⁿ k, Y ⁿ k) is the position of the defect detected in the coordinate system of the automatic image collection device 3, and the difference between these coordinates is the displacement of the coordinate system between the defect inspection device 2 and the automatic image collection device 3. . Therefore, in step S514, the overall control unit (host computer) 20 uses (N × K) pairs of coordinate pairs to derive a relational expression between these coordinate systems, and determines the position coordinates of the defect inspection apparatus 2 as an image. It can be converted into the position coordinates of the automatic collection device 3. (X ⁿ k, y ⁿ k) → (X ⁿ k, Y ⁿ The conversion equation of k) is expressed by the equation (Equation 1) shown in the first embodiment. The overall control unit (host computer) 20 converts this [A, B, C, D] into (N × K) pairs of coordinate pairs [(x ⁿ k, y ⁿ k), (X ⁿ k, Y ⁿ k)]. The way to find is (x ⁿ k, y ⁿ k) and (X ⁿ k, Y ⁿ k) After obtaining the offset [C, D] from each centroid position, [A, B] may be obtained by the least square method using a pseudo inverse matrix. In this way, the overall control unit (host computer) 20 determines the position coordinates (X ⁿ k, Y ⁿ k) position coordinates (x of the defect inspection apparatus 2 for calculating ⁿ k, y ⁿ A deviation correction coefficient [A, B, C, D] for k) can be calculated. In this way, the shift correction coefficients [A, B, C, D] can be calculated uniformly over the entire region on the target substrate 10 over all alignment blocks N.
[0057]
Next, in step S515, the overall control unit (host computer) 20 determines the imaging order of the defect number M on the target substrate 10 to be input to the image automatic collection device 3 stored and accumulated in the storage device 23. To do. In the first embodiment and the second embodiment, the imaging order is described as the order of the size of the defect, but there is no guarantee that it is optimal from the viewpoint of the total moving distance of the stage for imaging all the defects. There is an advantage that the total defect imaging time can be shortened by determining the observation order of defects on the basis of shortening the stage moving distance (the best is minimizing). The shortest path connecting a plurality of points on a plane at a predetermined position is, for example, Iri, Koshizuka “bit separate volume, computational geometry and geographic information processing” pp. ll0-121, Kyoritsu Shuppan (1986). Accordingly, the overall control unit (host computer) 20 moves the stage with respect to the defect position coordinates (xn, yn) obtained from the defect inspection apparatus 2 stored in the storage device 23 for M defects as described above. The order in which the defects are imaged is determined according to the minimum distance, and the rearranged order is set and registered in the storage device 23 as the image collection order n in the image automatic collection device 3. Since the number of defects on the target substrate 10 put into the image automatic collecting apparatus 3 is M, the number of defects to be imaged by the image automatic collecting apparatus 3 is M.
[0058]
Next, in step S516 (S410), the displacement correction is performed using the conversion equation shown in the above (Equation 1) and the defect position coordinates (Xn,) on the target substrate 10 in the coordinate system of the image automatic collection device 3 are corrected. Yn) is calculated. Then, the target substrate 10 is loaded onto the stage 118 by the transfer device 8.
Next, in step S517, the overall control unit (host computer) 20 acquires an image collection order of defects on the target substrate 10 to be input to the image automatic collection device 3 stored and accumulated in the storage device 23 (an image of this defect). The collection order is the observation order determined by the shortest route as described above.) Specify n = 1 as n.
Next, in step S518 (S411), the overall control group (host computer) 20 starts from the defect number n = 1 stored in the storage device 23 based on the position coordinates (Xn, Yn) of the defect. 16 is controlled so that the defect n positioned at (Xn, Yn) on the target substrate can be imaged by the electron detector 120 by moving the stage 118 on which the target substrate 10 is placed. Position the optical axis.
[0059]
Next, in step S519 (S412), the overall control unit (host computer) 20 sets the defect extraction magnification corresponding to the defect size from the defect number n = 1 stored in the storage device 23 in the memory unit 24. The amount of scanning deflection is selected from a table and switched to a low-magnification detection system (120 or the like) so that the selected magnification is obtained, or the scanning deflector 113 or the like (the scanning of the stage 118 may be combined). Is controlled so as to obtain an observation magnification, and an image of the defect is taken.
Next, in step S520 (S413), the next defect (n = n + 1) is designated according to the image collection order, and in step S521 (S414), the image input for all the defects existing on the target substrate is completed. In step S522 (S415), the target substrate 10 is unloaded from the stage 118 by the transfer device 8, and the process proceeds to defect imaging of the next target substrate. In this way, imaging of M defects can be realized with the shortest route, and imaging time can be shortened.
[0060]
In the above description, it is described that imaging is performed at the defect extraction magnification corresponding to the defect size (defect size) based on the correlation table between the defect size stored in the memory unit 24 and the imaging magnification. The fixed first imaging magnification is used, and at the time of other defect imaging, that is, for the defect imaging in step S519, the fixed second imaging magnification is used. At this time, using the defect imaged at the first imaging magnification for alignment as described above, it becomes possible to perform more detailed misalignment correction, and the defect positioning accuracy (alignment accuracy) at the time of defect imaging in step S519. As a result, the variation from the center of the image field of the defect after positioning is reduced, and the second imaging magnification is imaged with a field of view narrower than that obtained with the first imaging magnification, that is, with a high magnification. It becomes possible. That is, the second imaging magnification can be set to a higher magnification than the first imaging magnification. In this way, by setting the second imaging magnification to a higher magnification than the first imaging magnification, it becomes possible to capture even finer defects with high resolution on the image, and feature quantities of finer defects ( The size, shape, surface state, gray value, etc.) can be accurately extracted, and the nature (category) of the defect can be analyzed in detail and classified. In particular, the second imaging magnification can be imaged as a digital image signal at a magnification as high as possible (for example, 50000 times (0.02 μm can be taken as a digital image signal with 1 mm) to 30000 times (0.02 μm as 0.6 mm). ), More than that), the feature quantity of the defect can be extracted more accurately, and the property (category) of the defect can be analyzed and classified in more detail.
[0061]
In the above specific example, the case where the imaging magnification is switched in two stages according to the purpose of defect imaging has been described. However, as described above, classification is performed according to the defect size (defect size), and imaging is performed according to the class of the defect size. The magnification may be determined. Further, a method of applying an imaging magnification for imaging the size of the defect observed on the image with a predesignated image size (unit: pixel) may be used.
6A and 6B are connected by 601 and 602.
Next, the image automatic collection device 3 acquires a defect image at a higher magnification based on the defect position coordinates acquired from the defect inspection device 2, the number of defects on the target substrate, and the size of the defect. A fourth embodiment of the operation flow shown in FIG. 8B will be described with respect to differences from the third embodiment shown in FIG.
[0062]
First, in step S504a, the coordinate system sent from the inspection apparatus 2 is corrected using the alignment pattern formed on the target substrate 10. This alignment pattern is created using the same manufacturing process as the electronic circuit pattern formed on the substrate 10 to be inspected, and in order to easily confirm the center position, a circle, square, cross, etc. It is formed with a geometric pattern with symmetry. By using at least two alignment patterns at different positions, from the position coordinates (x, y) of the alignment pattern (mark) in the defect inspection apparatus 2 and the position coordinates (X, Y) of the alignment pattern in the image automatic collection apparatus 3 , (Equation 1) can be used to obtain coordinate conversion coefficients [A, B, C, D] for conversion from (x, y) to (X, Y), and (x, y) A coordinate conversion function G: G (x, y) = (X, Y) for conversion to (X, Y) can be determined. Naturally, the position coordinates (x, y) of the alignment pattern are detected also in the defect inspection apparatus 2, and the position coordinates (X, Y) of the alignment pattern are also detected in the image automatic collection apparatus 3. The position coordinates of the alignment pattern serve as a reference point common to the defect inspection apparatus 2 and the automatic image collection apparatus 3.
[0063]
Second, in step S507 ′, the overall control unit (host computer) 20 determines the position coordinates of the defect from the alignment block order n = 1 and the alignment defect order k = 1 stored in the storage device 23 in step 504a. Corrected by the derived coordinate transformation function G, corrected position coordinates G (x ⁿ k, y ⁿ k), the stage control unit 16 is driven and controlled to move the stage 118 on which the target substrate 10 is placed, thereby moving G (x ⁿ k, y ⁿ The defect is positioned so that the defect located at k) can be imaged by the electron detector 120. As described above, the coordinate conversion function G can improve the positioning accuracy (alignment accuracy) of the alignment defect. As a result, the variation from the center of the image field of the defect after positioning is reduced, and reliable alignment is achieved. Implementation becomes possible.
The third point is that in step S517 ′, the overall control unit (host computer) 20 stores and accumulates the offset values (offsetx, offsety) for X and Y as 0 in the storage device 23.
Fourth, in step S518 ′, the overall control unit (host computer) 20 uses the offset value (offsetx, offsety) obtained at the previous point adjacent to the defect number n = 1 stored in the storage device 23. Based on the corrected position coordinates (Xn + offsetx, Yn + offsety) of the defect, the stage controller 16 is driven and controlled to move the stage 118 on which the target substrate 10 is placed (Xn + offsetx, Yn + offsety). The defect n is positioned on the optical axis so that the electron detector 120 can pick up an image of the defect n. In this manner, the defect n is imaged by the electron detector 120 by correcting the position coordinates (Xn, Yn) of the defect with the offset value (offsetx, offsety) obtained at the adjacent point as described later. It becomes possible to position with high accuracy within the visual field.
[0064]
Fifth, in step S519a, the image processing device 15 calculates a difference image signal indicating a defect from the acquired defect image signal using, for example, a reference image signal, and the position of the defect from the calculated difference image signal. This is a point to detect (Xn ′, Yn ′).
[0065]
Sixth, in step S519b, the offset value (Xn ′, Yn ′) calculated in step S519a and the offset value (Xn, Yn) calculated using the correction function in step S516 are calculated based on the difference between them. offsetx, offsety) is calculated. Thus, the offset value (offsetx, offsety) is obtained from the difference between the defect position (Xn ′, Yn ′) calculated in step S519a and the defect position (Xn, Yn) calculated using the correction function in step S516. It is possible to calculate.
As for the offset values (offsetx, offsety) described in the third, fourth, fifth, and sixth, a defect coordinate value obtained by processing with the coordinate correction function F obtained by alignment and an actual defect image are acquired. The deviation from the true defect coordinate value obtained from the image is expressed. Since the stage movement between the defect to be observed sequentially is based on the minimum concept, two adjacent defects based on the observation order are relatively close and the offset value is also indicated by a small value. Accordingly, it is possible to acquire a defect image signal in step S519a and calculate an offset value in step S519b. For this reason, if the calculated offset value is used in the next defect positioning, a more accurate defect positioning can be performed.
Except for the first and sixth points described above, the operation and processing are the same as those of the third embodiment shown in FIG.
[0066]
Moreover, FIG. 8A and FIG. 8B are connected by 601 'and 602'.
Note that steps S515 to S522 shown in FIG. 8B may be executed after steps S501 to S514 in the first half shown in FIG. 6A, and steps S515 to S522 shown in FIG. 6B after steps S501 and S514 shown in FIG. 8A. May be executed.
[0067]
As described above, the image capturing magnification of the image is set according to the defect size in the image automatic collecting apparatus 3, but the image capturing magnification is formed on a portion on the target substrate (wafer substrate) to be imaged. It may be determined according to the type of circuit pattern. A circuit pattern on a target substrate such as a semiconductor wafer is fine, and a reduction in image magnification means that a sampling frequency is reduced when this is captured by a digital image. Therefore, when this sampling frequency is less than half the spatial frequency of the circuit pattern formed on the target substrate, a kind of interference fringe pattern that does not originally exist on the target substrate is superimposed due to aliasing, thereby causing a defect. May cause difficulties in observation. For this reason, it is necessary to set the imaging magnification (defect extraction magnification and defect observation magnification) high in a portion where the spatial frequency of the circuit pattern is high, and to set the imaging magnification (defect extraction magnification and defect observation magnification) low in a portion where the spatial frequency is low. . Therefore, it is possible to define the imaging magnification of each image on the target substrate and prevent the generation of noise patterns due to aliasing as described above. Accordingly, the overall control unit (host computer) 20 records in advance design information relating to the type of circuit pattern (spatial frequency is high or low) formed for each partial region on the target substrate 10 to be input. Input from a CAD system (not shown) or a management system (not shown) managing the production line using the input means 21 such as a medium or the network 22 and stores it in the memory unit 24 or the storage device 23. It is necessary to keep it. Then, the overall control unit (host computer) 20 obtains the minimum imaging magnification for each region on the target substrate 10 based on the design information (spatial frequency) related to the type of the circuit pattern in advance and stores it in the memory unit 24. By storing them, it is possible to confirm whether or not the imaging magnification (defect extraction magnification, defect observation magnification) for each region of the target substrate 10 to be input is appropriate.
[0068]
That is, the overall control unit (host computer) 20 can extract from the memory unit 24 the lowest imaging magnification in that area from the position coordinates of the defects detected from the defect inspection apparatus 2 and stored in the storage device 23. . Therefore, the overall control unit 20 satisfies the minimum imaging magnification condition in the area where the defect exists, with the defect extraction magnification corresponding to the defect size in step S406 and steps S412 and S412a and the defect observation magnification in step S407c and step S412d. If it is not satisfied, the image acquisition of this defect is skipped in the same step as steps S407b and S412c which are skipped according to the defect size shown in FIGS. 5A and 5B. In this way, the overall control unit 20 generates a noise pattern from the background of the defect (circuit pattern) by capturing the defect by satisfying the defect extraction magnification and the defect observation magnification with the minimum imaging magnification in the area where the defect exists. Thus, it is possible to acquire a digital image signal that faithfully shows a defect, to accurately perform misalignment correction (alignment), and to improve the reliability of detailed analysis of the feature amount and property of the defect.
[0069]
【The invention's effect】
According to the present invention, since the difference in the coordinate system existing between the defect inspection apparatus and the defect inspection apparatus can be stably corrected, even a fine defect detected by the defect inspection apparatus can be stably captured in a short search time. As a result, a high-resolution digital image signal imaged at a high imaging magnification (for example, 10,000 times or more) that can analyze in detail the feature amount (size, shape, surface state, gray value, etc.) and property (category) of the defect It is possible to realize an automatic image collecting apparatus and method using a scanning electron microscope that can acquire the above.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the role of an automatic image collecting apparatus according to the present invention in a semiconductor manufacturing process.
FIG. 2 is a schematic configuration diagram showing an embodiment of an automatic image collecting apparatus according to the present invention.
FIG. 3 is a flowchart showing a first embodiment for performing automatic image collection processing in the automatic image collection apparatus according to the present invention;
FIG. 4A is a flowchart showing the first half of a second embodiment for performing automatic image collection processing in the automatic image collection apparatus according to the present invention.
FIG. 4B is a flowchart showing the second half of the second embodiment in which automatic image collection processing is performed in the automatic image collection apparatus according to the present invention.
FIG. 5 is a diagram illustrating an example of parameter setting.
FIG. 6A is a flowchart showing the first half of a third embodiment for performing automatic image collection processing in the automatic image collection apparatus according to the present invention;
FIG. 6B is a flowchart showing the second half of the third embodiment shown in FIG. 6A.
FIG. 7 is a diagram illustrating an example in which an inspection target is divided into segmental areas.
FIG. 8A is a flowchart showing the first half of a fourth embodiment for performing automatic image collection processing in the automatic image collection apparatus according to the present invention;
FIG. 8B is a flowchart showing the second half of the fourth embodiment shown in FIG. 8A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Probe inspection, 2 ... Defect inspection apparatus (appearance inspection apparatus), 3 ... Image automatic collection apparatus, 4 ... Appearance inspection result, 5 ... Defect image, 6 ... Screen which shows occurrence frequency according to defect mode, 7 ... Quality control System: 8 ... Conveying device, 10 ... Substrate, 13 ... Image input device (image input unit), 14 ... Image recording device (image storage device, image storage unit), 15 ... Image processing device, 16 ... Stage control unit DESCRIPTION OF SYMBOLS 17 ... Conveyance control part, 18 ... Monitor, 20 ... Overall control part (host computer), 21 ... Input means, such as keyboard and mouse, 22 ... Network, 24 ... Memory part, 25 ... Bus, 101 ... Scanning electron microscope , 111 ... electron gun, 112 ... converging lens (condenser lens), 113 ... scanning deflector, 114 ... objective lens, 115 ... ground electrode, 117 ... retarding electrode, 118 ... stay , 120 ... electronic detector, 121 ... amplifier, 131 ... A / D converter, 132 ... preprocessing circuit.

Claims (8)

Each of a large number of defects existing on each target substrate to be input is positioned in the imaging field of view in the second coordinate system, and each defect positioned in the imaging field of view is determined according to the size of each defect. A scanning electron beam microscope that captures an electron beam image signal of each defect by imaging at an imaging magnification set in the step, and stores the acquired electron beam image signal of each defect in an image storage unit ,
A storage unit for acquiring and storing information on the dimensions and the position coordinates in the first coordinate system for a large number of defects present on each target substrate to be input to the scanning electron microscope from the visual inspection apparatus ;
The plurality of defects based on the information about the dimensions and the position coordinates in the first coordinate system of the plurality of defects existing on each target substrate acquired from the appearance inspection apparatus stored in the storage unit. The position coordinate information in the first coordinate system is rearranged in the descending order according to the size of each defect, and the number of alignments is sequentially increased from the large-sized defect that satisfies a desired dimension in the rearranged multiple defects. The position coordinates in the first coordinate system of each defect across the selected number are selected, and based on the position coordinates in the first coordinate system of each defect across the selected number of alignments, each defect has a low imaging magnification corresponding to the dimension Are sequentially positioned in the field of view of each of the images, and each sequentially positioned defect is imaged at the low imaging magnification, and an electron beam image signal of each defect is stored in the image storage unit. Based on the stored electron beam image signal of each defect, the position coordinates of each defect in the second coordinate system are sequentially calculated, and in the sequentially calculated second coordinate system for each defect over the number of alignments. From the relationship between the position coordinates and the position coordinates in the first coordinate system, a coordinate conversion equation for the position coordinates of the defect in the first coordinate system for calculating the position coordinates of the aligned defect in the second coordinate system A deviation correction coefficient calculating means for calculating a deviation correction coefficient ;
A position coordinate in the first coordinate system for each defect other than that used for the alignment is subjected to a shift correction by a coordinate conversion formula using a shift correction coefficient calculated by the shift correction coefficient calculating means, and the second coordinate system is used. A high-order system that sequentially calculates aligned position coordinates in the coordinate system and obtains an electron beam image corresponding to the size of each defect based on the sequentially calculated position coordinates in the second coordinate system for each defect. Image capturing means positioned in the field of view of the imaging magnification, capturing each sequentially positioned defect at the high imaging magnification, collecting an electron beam image signal of each defect, and storing it in the image storage unit An automatic image collecting apparatus characterized by that. In the shift correction coefficient calculation means, when sequentially calculating the position coordinates of each defect in the second coordinate system based on the electron beam image signal of each defect stored sequentially, the electron of each defect stored sequentially If the size of each defect is detected based on the line image signal and the size of each detected defect is larger than the specified size, each defect is skipped to the next defect without being imaged. The automatic image collection apparatus according to claim 1, wherein the automatic image collection apparatus is configured to perform the above-described configuration . Each of a large number of defects existing on each target substrate to be input is positioned in the imaging field of view in the second coordinate system, and each defect positioned in the imaging field of view is determined according to the size of each defect. A scanning electron beam microscope that captures an electron beam image signal of each defect by imaging at an imaging magnification set in the step, and stores the acquired electron beam image signal of each defect in an image storage unit ,
A storage unit for acquiring and storing information on the dimensions and the position coordinates in the first coordinate system for a large number of defects present on each target substrate to be input to the scanning electron microscope from the visual inspection apparatus ;
Area setting means for dividing and setting and registering each of the target substrates into N alignment blocks;
In the region setting means, based on the information about the dimensions and the position coordinates in the first coordinate system for a large number of defects present on each target substrate acquired from the appearance inspection apparatus stored in the storage unit rearranged defects present in each alignment block on each of the target substrate that is set and registered in the respective alignment block to a large order of the dimensions, the specified defect size from the alignment block rearranged defect group for each A predetermined number K of defects having the closest defect size is selected, and each defect is determined based on the position coordinates in the first coordinate system of each defect across the predetermined number K of defects selected for each alignment block. The defect is sequentially positioned in the field of view of the low imaging magnification corresponding to the dimension, and each defect sequentially positioned for each alignment block is photographed at the low imaging magnification. Then, the electron beam image signal of each defect is stored in the image storage unit, and N × K sets of defects over the number of alignment blocks based on the electron beam image signal of each defect sequentially stored for each alignment block. The position coordinates in the second coordinate system are sequentially calculated, and the relationship between the sequentially calculated position coordinates in the second coordinate system and the position coordinates in the first coordinate system for each of the N × K sets of defects is calculated. A deviation correction coefficient calculating means for calculating a deviation correction coefficient of a coordinate conversion formula for the position coordinates of the defect in the first coordinate system for calculating the position coordinates of the aligned defect in the second coordinate system ;
A position coordinate in the first coordinate system for each defect other than that used for the alignment is subjected to a shift correction by a coordinate conversion formula using a shift correction coefficient calculated by the shift correction coefficient calculating means, and the second coordinate system is used. The position coordinates in the coordinate system are sequentially calculated, and an electron beam image corresponding to the dimension of each defect is acquired based on the position coordinates in the second coordinate system that are aligned for the sequentially calculated defects. Image acquisition control means for positioning in the field of view of the imaging magnification, imaging each sequentially positioned defect at the high imaging magnification, collecting an electron beam image signal of each defect, and storing it in the image storage unit An automatic image collecting apparatus characterized by that. And analyzing means for calculating defect feature values from the electron beam image signals of the defects collected and stored in the image storage unit, and classifying the defect properties by analyzing the calculated defect feature values. The image collecting apparatus according to claim 1, further comprising an image collecting apparatus. A storage unit is provided for acquiring and storing information on the dimensions and the position coordinates in the first coordinate system for a large number of defects existing on each target substrate to be input, from each of the input target objects. Each of a large number of defects existing on the target substrate is positioned in the imaging field by the second coordinate system, and each defect positioned in the imaging field is set in accordance with the size of each defect. An image auto-collection method using a scanning electron beam microscope that captures an electron beam image signal of each defect by imaging at a magnification, and stores the acquired electron beam image signal of each defect in an image storage unit ,
Based on the information about the dimensions and the position coordinates in the first coordinate system for the multiple defects existing on each target substrate acquired from the visual inspection apparatus stored in the storage unit, the multiple defects The position coordinate information in the first coordinate system is rearranged in the descending order according to the size of each defect, and the number of alignments is sequentially increased from the large-sized defect that satisfies a desired dimension in the rearranged multiple defects. The position coordinates in the first coordinate system of each defect over the selected number are selected, and based on the position coordinates in the first coordinate system for each defect over the selected number of alignment, each defect is low imaging magnification corresponding to the dimensions Are sequentially positioned in the field of view of each of the images, and each sequentially positioned defect is imaged at the low imaging magnification, and an electron beam image signal of each defect is stored in the image storage unit. Based on the stored electron beam image signal of each defect, the position coordinates of each defect in the second coordinate system are sequentially calculated, and in the sequentially calculated second coordinate system for each defect over the number of alignments. From the relationship between the position coordinates and the position coordinates in the first coordinate system, a coordinate conversion equation for the position coordinates of the defect in the first coordinate system for calculating the position coordinates of the aligned defect in the second coordinate system A deviation correction coefficient calculation process for calculating a deviation correction coefficient;
A position coordinate in the first coordinate system for each defect other than that used for the alignment is subjected to a shift correction by a coordinate conversion formula using a shift correction coefficient calculated by the shift correction coefficient calculating means, and the second coordinate system is used. A high-order system that sequentially calculates aligned position coordinates in the coordinate system and obtains an electron beam image corresponding to the size of each defect based on the sequentially calculated position coordinates in the second coordinate system for each defect. An image collecting process of positioning in the field of view of the imaging magnification, imaging each sequentially positioned defect at the high imaging magnification, collecting an electron beam image signal of each defect, and storing it in the image storage unit A method for automatically collecting images . When sequentially calculating the position coordinates of each defect in the second coordinate system based on the electron beam image signal of each defect stored sequentially in the shift correction coefficient calculation process, the electron of each defect stored sequentially If the size of each defect is detected based on the line image signal and the size of each detected defect is larger than the specified size, each defect is skipped to the next defect without being imaged. The image automatic collection method according to claim 5, wherein: A storage unit is provided for acquiring and storing information on the dimensions and the position coordinates in the first coordinate system for a large number of defects existing on each target substrate to be input, from each of the input target objects. Each of a large number of defects existing on the target substrate is positioned in the imaging field by the second coordinate system, and each defect positioned in the imaging field is set in accordance with the size of each defect. An image auto-collection method using a scanning electron beam microscope that captures an electron beam image signal of each defect by imaging at a magnification, and stores the acquired electron beam image signal of each defect in an image storage unit,
Each of the target substrates based on the information on the dimensions and the position coordinates in the first coordinate system for a large number of defects existing on each of the target substrates acquired from the appearance inspection apparatus stored in the storage unit The defects present in each alignment block are rearranged in the descending order of the size for each of the N alignment blocks divided above, and the defect size closest to the specified defect size from the defect group rearranged for each alignment block. A predetermined number K of defects having a predetermined number of defects is selected, and each defect corresponds to the dimension based on the position coordinates in the first coordinate system of each defect across the predetermined number of defects selected for each alignment block. Sequentially position within the field of view of the low imaging magnification, and image each defect sequentially positioned for each alignment block at the low imaging magnification A defect electron beam image signal is stored in the image storage unit, and the second of N × K sets of defects over the number of alignment blocks based on the electron beam image signal of each defect sequentially stored for each alignment block. Position coordinates in the coordinate system are sequentially calculated, and the second position is calculated based on the relationship between the sequentially calculated position coordinates in the second coordinate system and the position coordinates in the first coordinate system for each of the N × K sets of defects. A shift correction coefficient calculation process for calculating a shift correction coefficient of a coordinate conversion equation for the position coordinates of the defect in the first coordinate system for calculating the position coordinates of the aligned defect in the coordinate system of
A position coordinate in the first coordinate system for each defect other than that used for the alignment is subjected to a shift correction by a coordinate conversion formula using a shift correction coefficient calculated by the shift correction coefficient calculating means, and the second coordinate system is used. A high-order system that sequentially calculates aligned position coordinates in the coordinate system and obtains an electron beam image corresponding to the size of each defect based on the sequentially calculated position coordinates in the second coordinate system for each defect. An image collecting process of positioning in the field of view of the imaging magnification, imaging each sequentially positioned defect at the high imaging magnification, collecting an electron beam image signal of each defect, and storing it in the image storage unit A method for automatically collecting images . Furthermore, an analysis process for classifying the nature of the defect by calculating the feature amount of the defect from the electron beam image signal of the defect collected and stored in the image storage unit and analyzing the calculated feature amount of the defect is performed. 8. The method for automatically collecting images according to claim 5 or 7, further comprising:

Images