JP3779629B2

JP3779629B2 - Semiconductor device manufacturing method and plasma processing method

Info

Publication number: JP3779629B2
Application number: JP2002043083A
Authority: JP
Inventors: 博之中野; 俊彦中田
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2002-02-20
Filing date: 2002-02-20
Publication date: 2006-05-31
Anticipated expiration: 2022-02-20
Also published as: JP2003243375A

Description

【０００１】
【発明の属する技術分野】
本発明は、半導体基板や液晶基板などの半導体の製造方法およびその装置に係り、特に、薄膜の生成（成膜）やエッチング等の加工を行う処理室（真空処理室）内に浮遊した異物、及び、処理室の汚染状況を、ｉｎ−ｓｉｔｕ計測する機能を備えた半導体の製造方法並びにプロセス処理方法およびその装置に関する。
【０００２】
【従来の技術】
エッチング装置を始めとして、プラズマを用いた処理が半導体製造工程や液晶表示装置用基板製造工程に広く適用されている。
【０００３】
このように、プラズマを用いた処理装置では、プラズマ処理による例えばエッチング反応によって生成された反応生成物が、プラズマ処理室の壁面あるいは電極に堆積し、これが時間経過に伴い、剥離して浮遊異物となることが知られている。この浮遊異物は、エッチング処理が終了しプラズマ放電が停止した瞬間に、ウェハ上に落下して付着異物となり、回路の特性不良やパターン外観不良を引き起こす。そして、最終的には、歩留まりの低下や素子の信頼性低下の原因となる。
【０００４】
上記ウェハ等の被処理基板の表面に付着した異物を検査する装置は、多数報告され実用化されているが、これらは、プラズマ処理装置から一旦被処理基板を抜き出して検査を行うもので、異物が多く発生していると判った時点では、既に他のウェハの処理が進んでおり、不良の大量発生による歩留まりの低下の問題がある。また、処理後の評価では、処理室内の異物発生の分布、経時変化などは判らない。従って、処理室内の汚染状況をｉｎ−ｓｉｔｕでリアルタイムモニタする技術が、半導体製造や液晶製造等の分野で求められている。
【０００５】
処理室内で浮遊する異物の大きさは、サブミクロンから数百μｍの範囲であるが、２５６ＭｂｉｔＤＲＡＭ(Dynamic Random Access Memory)、さらには１ＧｂｉｔＤＲＡＭへと高集積化が進む半導体の分野においては、回路パターンの最小線幅は０．２５〜０．１８μｍと微細化の一途を辿っており、検出すべき異物の大きさもサブミクロンオーダが要求されている。
【０００６】
プラズマ処理室等の処理室（真空処理室）内に浮遊した異物をモニタする従来技術としては、特開昭５７−１１８６３０号公報（従来技術１）、特開平３−２５３５５号公報（従来技術２）、特開平３−１４７３１７号公報（従来技術３）、特開平６−８２３５８号公報（従来技術４）、特開平６−１２４９０２号公報（従来技術５）、特開平１０−２１３５３９号公報（従来技術６）、特開平１１−２５１２５２号公報（従来技術７）、および特開平１１−３３００５３号公報（従来技術８）に開示された技術が挙げられる。
【０００７】
上記従来技術１には、反応空間における自己発光光のスペクトルと異なったスペクトルを有する平行光を反応空間に照射する手段と、上記平行光の照射を受けて上記反応空間において発生する微粒子からの散乱光を検出する手段とを、具備した蒸着装置が開示されている。
【０００８】
また、上記従来技術２には、半導体装置用基板表面に付着した微細粒子及び浮遊している微細粒子を、レーザ光による散乱を用いて測定する微細粒子測定装置において、波長が同一で相互の位相差がある所定の周波数で変調された２本のレーザ光を発生させるレーザ光位相変調部と、上記２本のレーザ光を上記の測定対象である微細粒子を含む空間において交差させる光学系と、上記２本のレーザ光の交差された領域において測定対象である微細粒子により散乱させた光を受光し、電気信号に変換する光検出部と、この散乱光による電気信号の中で上記レーザ光位相変調部での位相変調信号と周波数が同一または２倍で、かつ上記位相変調信号との位相差が時間的に一定である信号成分を取り出す信号処理部とを、備えた微細粒子測定装置が開示されている。
【０００９】
また、上記従来技術３には、コヒーレント光を走査照射して反応容器内で散乱する光をその場で発生させるステップと、上記反応容器内で散乱する光を検出するステップとを含み、それにより上記散乱光を解析することで、上記反応容器内の汚染状況を測定する技術が記載されている。
【００１０】
また、上記従来技術４には、レーザ光を生成するレーザ手段と、観測されるべき粒子を含むプラズマ処理ツールの反応室内の領域を上記レーザ光で走査するスキャナ手段と、上記領域内の粒子によって散乱したレーザ光のビデオ信号を生成するビデオカメラと、上記ビデオ信号のイメージを処理し表示する手段とを、有する粒子検出器が記載されている。
【００１１】
また、上記従来技術５には、プラズマ処理室内のプラズマ発生領域を観測するカメラ装置と、該カメラ装置により得られた画像を処理して目的とする情報を得るデータ処理部と、該データ処理部にて得られた情報に基づいてパーティクルを減少させるように排気手段、プロセスガス導入手段、高周波電圧印加手段及びパージガス導入手段のうち少なくとも１つを制御する制御部とを、備えたプラズマ処理装置が記載されている。
【００１２】
また、上記従来技術６には、測定体積を横切って照射する光ビームを送出する光送出器と、光検出器と上記測定体積からの散乱光を集光してその光を上記光検出器に向ける光学系とを含み、その光検出器に向けられた光の強度を表す信号をその光検出器が発生するように構成した検出器と、前記光検出器からの信号を分析するように相互接続され、前記光検出器からの信号の中のパルスを検出するパルス検出器と、微粒子に対応しその微粒子が前記測定体積の中を動く間の前記ビームによる複数回の照射に伴う前記微粒子による散乱光に起因する一連のパルスを特定する事象検出器とを含む信号処理手段とを含む微粒子センサが記載されている。
【００１３】
また、上記従来技術７には、処理室内にプラズマを発生させ、該プラズマによって被処理対象物に対して処理するプラズマ処理装置において、所望の波長を有し、所望の周波数で強度変調した光を上記処理室内に照射する照射光学系と、上記処理室から得られる散乱光を上記所望の波長成分で分離して受光して信号に変換する散乱光検出光学系と、該散乱光検出光学系から得られる信号から上記強度変調した所望の周波数成分を抽出することによってプラズマ中若しくはその近傍に浮遊した異物を示す信号を上記プラズマによるものから分離して検出する異物信号抽出手段とを備えたプラズマ浮遊異物計測装置を設けることが開示されている。
【００１４】
また、上記従来技術８には、処理室内にプラズマを発生させ、該プラズマによって被処理対象物に対して処理するプラズマ処理装置において、互いに異なる波長を有し、所望の周波数で強度変調した複数のビームを上記処理室内に照射する照射光学系と、その散乱光を互いに異なる波長成分で分離して受光して複数の信号に変換する散乱光検出光学系と、該散乱光検出光学系から得られる複数の信号から上記強度変調した所望の周波数成分を抽出することによってプラズマ中若しくはその近傍に浮遊した異物を示す複数の信号を上記プラズマによるものから分離して検出する異物信号抽出手段とを備えたプラズマ浮遊異物計測装置を設けることが開示されている。
【００１５】
【発明が解決しようとする課題】
上記した従来技術１〜６は、プラズマ処理室の側面に設けられた観測用窓からレーザ光を照射し、対向した側面あるいはその他の側面に設けられた上記レーザ照射用観測窓とは異なる観測用窓から、レーザ前方散乱光や側方散乱光を検出するものである。したがって、これらの前方散乱光や側方散乱光を検出する方式では、照射光学系と検出光学系とが各々異なるユニットで形成され、これらを取り付ける観測用窓も２つ必要であり、また、光軸調整等も、照射・検出光学系で各々行わなければならず、取り扱いが面倒なものとなっていた。
【００１６】
また、通常、プラズマ処理室などの処理室の側面の観測用窓は、プラズマ発光などをモニタするためにほとんどの機種に設けられているが、この観測窓は１つのみしか備え付けられていない場合も少なくない。従って、観測用窓を２つ必要とする従来手法は、観測用窓を１つしか備えていない処理室をもつ製造装置には、適用することができないという課題がある。
【００１７】
さらに、前方散乱光や側方散乱光を検出する従来方式においては、プラズマ処理室へ照射する照射ビームを回転走査させて、ウェハ等の被処理基板の全面上の異物発生状況を観測しようとした場合には、多数の観測窓と検出光学系とを必要とし、大幅なコストアップ要因となる上、多数の観測窓や検出光学系を設けることも、スペースファクター上の制約から実際には非常に困難であると予想される。
【００１８】
一方、２５６ＭｂｉｔＤＲＡＭ、さらには１ＧｂｉｔＤＲＡＭへと高集積化が進む半導体の分野においては、回路パターンの最小線幅は０．２５〜０．１８μｍと微細化の一途を辿っており、検出すべき異物の大きさもサブミクロンオーダが要求されている。しかし、従来技術１〜６では、異物散乱光とプラズマ発光の分離が困難であるため、比較的大きな異物の観測に適用が限定され、サブミクロンオーダの微小異物を検出することは困難であると考えられる。
【００１９】
また、従来技術７、８には、プラズマ中若しくはその近傍に浮遊した異物を検出することについては記載されているが、プラズマ処理室の内壁に付着若しくは堆積する汚染状態を検出することについては考慮されていなかった。
【００２０】
本発明の第１の目的は、上記課題を解決すべく、エッチング、スパッタ、ＣＶＤなどのプラズマ処理装置におけるプラズマ処理室の内壁の汚染状況を検出できるようにして被処理基板上に異物が多く発生するのを予測して早期に清掃等の対策を施して多量の不良の発生を防止できる半導体の製造方法並びにプラズマ処理方法およびその装置を提供することにある。
【００２１】
また、本発明の第２の目的は、プラズマ処理室の内壁の汚染状況を検出でき、しかもプラズマ処理室内に浮遊した異物の検出をもできるようにして、被処理基板上に異物が多く発生するのを防止する対策を早めに施して多量の不良の発生を防止できる半導体の製造方法並びにプラズマ処理方法およびその装置を提供することにある。
【００２２】
また、本発明の第３の目的は、内壁の汚染状態や浮遊した異物を検出する照射・検出光学系をコンパクトにして限られた狭いスペースに取り付けができるようにしたプラズマ処理方法およびその装置を提供することになる。
【００２３】
【課題を解決するための手段】
上記目的を達成するために、本発明は、処理室内にプラズマを発生させ、該発生したプラズマによって半導体基板に対して処理して半導体を製造する半導体の製造方法並びにプラズマ処理方法およびその装置において、光ビームを観察窓を通して前記処理室内に照射する照射ステップと、該照射ステップにより前記処理室の内壁からの凹凸状態の変化（反応生成物の堆積やダメージ等）に伴って変化が生じる反射光像を観察窓を通して結像光学系で結像させて検出器で受光して受光信号として検出する検出ステップと、該検出ステップによって検出された受光信号の変化を基にして算出される前記処理室の内壁の汚染状況を基に前記半導体基板に対するプラズマ処理を制御する制御ステップとを有することを特徴とする。
【００２４】
また、本発明は、処理室内にプラズマを発生させ、該発生したプラズマによって半導体基板に対して処理して半導体を製造する半導体の製造方法並びにプラズマ処理方法およびその装置において、所望の周波数で強度変調したビームを観察窓を通して前記処理室内に照射する照射ステップと、該照射ステップにより照射された前記処理室の内壁からの凹凸状態の変化に伴って変化が生じる反射光像を観察窓を通して結像光学系で結像させて検出器で受光して受光信号として検出し、該検出された受光信号の中から前記強度変調周波数成分を抽出することによって処理室の内壁の凹凸状態の変化を示す信号をプラズマによるものから分離して検出する検出ステップと、該検出ステップにより検出された信号の変化を基にして算出される前記処理室の内壁の汚染状況を基に前記半導体基板に対するプラズマ処理を制御する制御ステップとを有することを特徴とする。
【００２５】
また、本発明は、前記検出ステップにおいて、前記結像光学系で結像させて検出器で受光する光像がスペックルパターン像であることを特徴とする。
また、本発明は、前記検出ステップにおいて、前記反射光像を観察窓を通して結像光学系で結像させて検出器で受光する際、前記処理室内のプラズマから発生する光をフィルタで遮光することを特徴とする。
また、本発明は、前記照射ステップにおいて、前記ビームを処理室内に照射する際、前記処理室の内壁の複数個所に照射できるように前記ビームを走査することを特徴とする。
【００２６】
また、本発明は、前記照射ステップにおける前記ビームを照射する観察窓と前記検出ステップにおける前記反射光像を通す観察窓とが同一であることを特徴とする。
また、本発明は、前記検出ステップにおいて、前記結像光学系の結像位置に設置された絞りによって制限された光像を検出器で受光することを特徴とする。
【００２７】
また、本発明は、処理室内にプラズマを発生させ、該発生したプラズマによって半導体基板に対して処理して半導体を製造する半導体の製造方法並びにプラズマ処理方法およびその装置において、所望の周波数で強度変調したビームを観察窓を通して前記処理室内に照射する照射ステップと、該照射ステップにより前記処理室の内部からの観察窓を通して得られる反射光像を分岐光学系で分岐し、該分岐された一方の反射光像を第１の結像光学系で結像させて第１の検出器で受光して第１の受光信号に変換し、該変換された第１の受光信号の中から前記強度変調周波数成分を抽出することによってプラズマ中若しくはその近傍に浮遊した異物を示す第１の信号をプラズマによるものから分離して検出し、前記分岐された他方の反射光像を第２の結像光学系で結像させて第２の検出器で受光して第２の受光信号として検出し、該検出された第２の受光信号の中から前記強度変調周波数成分を抽出することによって処理室の内壁の凹凸状態の変化を示す第２の信号をプラズマによるものから分離して検出する検出ステップと、該検出ステップで検出された第１の信号を基にして算出されるプラズマ中若しくはその近傍に浮遊する異物の発生状況または前記検出ステップで検出された第２の信号の変化を基にして算出される前記処理室の内壁の汚染状況を基に前記半導体基板に対するプラズマ処理を制御する制御ステップとを有することを特徴とする。
また、本発明は、前記第２の結像光学系の結像位置に絞りを設置して異物やプラズマからの光を制限して減少させることを特徴とする。
また、本発明は、前記第１の結像光学系の結像位置に空間フィルタを設置して処理室の内壁からの散乱反射光を遮光することを特徴とする。
【００２８】
また、本発明は、処理室の内壁の汚染状況の判定を、処理室内壁への反応生成物の付着及び／又はプラズマによるダメージによる処理室内壁の表面状態（凹凸状態）に関連して、予め実験的に得られた信号と前記受光信号とを比較判定することにより行うことを特徴とする。
また、本発明は、処理室の内壁の汚染状況の判定と同時に，処理室内壁に付着した反応生成物の膜厚に関連して，予め実験的に得られた信号と付着膜厚の関係から，該付着した反応生成物の膜厚を求めることを特徴とする。
また、本発明は、処理室の内壁の汚染状況と浮遊異物については、個数、大きさ、分布とを判別してデイスプレイ上に表示することを特徴とする。
【００２９】
以上説明したように、本発明によれば、処理室の内壁の汚染状況を常に把握できることによって、早期に浮遊異物が多く発生するのを予測して、被処理基板へのプラズマ処理の制御をする（被処理基板の投入を中止してクリーニングを実行するなど、また、プロセス処理の条件を監視するなど様々な対策を施す）ことによって、多量に不良が発生のを防止して、歩留まりを著しく向上させることができる。
【００３０】
【発明の実施の形態】
以下、本発明に係る実施の形態を、図１〜図１５を用いて説明する。
【００３１】
なお、以下に述べる本発明の各実施形態では、プラズマドライエッチング装置に利用されている、平行平板形プラズマエッチング装置への適用例を示すが、本発明の適用範囲はこれに限定されるものではなく、本発明は、スパッタ装置やＣＶＤ装置などの薄膜生成（成膜）装置、あるいは、ＥＣＲエッチング装置やマイクロ波エッチング装置、またはアッシング装置などの各種薄膜生成、加工装置への適用が可能である。
【００３２】
まず、本発明に係る第１の実施の形態を、図１〜図１３を用いて説明する。図１は、本第１の実施の形態に係る、処理室内壁汚染状況モニタリング機能付きプラズマ中浮遊異物計測装置をもつプラズマエッチング処理装置の構成を示す図である。即ち、本発明に係る第１の実施の形態は、エッチングやアッシングなどの各種処理装置に、処理室内壁の汚染状況をモニタリングできる計測装置を備えることにある。
【００３３】
図１に示すように、エッチング処理装置では、シグナルジェネレータ８３からの高周波信号によりパワーアンプ８４の出力電圧を変調し、この高周波電圧を分配器８５によって分配して、プラズマ処理室８６内において互いに平行に配置した上部電極８１と下部電極８２の間に印加して、両電極間での放電によりエッチグ用ガスからプラズマ７１を発生させ、その活性種で被処理体としての半導体基板（ウェハ）Ｗをエッチングする。高周波信号としては、例えば４００ｋＨｚが用いられる。
【００３４】
処理室内壁汚染状況モニタリング機能付きプラズマ中浮遊異物計測装置２は、主としてレーザ照明光学系２０００と、散乱光検出光学系２００１と、制御・信号処理系６０００とにより構成され、レーザ照明光学系２０００と散乱光検出光学系２００１における照明光出口部・検出光入口部は、プラズマ処理室８６の側面に設けられた観測用窓１０に対向するように配置されている。
【００３５】
レーザ照明光学系２０００では、まず、レーザ光源（例えば、波長５３２ｎｍ）１２から出射されたＳ偏光ビーム１０１をＡＯ（Ａｃｏｕｓｔｏ−Ｏｐｔｉｃａｌ）変調器１４に入射する。ＡＯ偏光器１４には、計算機４２からの制御信号に基づき、発振器１３から出力された例えば周波数１７０ｋＨｚ、好ましくはデューティ５０％の矩形波信号を印加して、Ｓ偏光ビームを上記周波数で強度変調する。ここで、エッチング処理装置の電極に印加する高周波電圧を４００ｋＨｚとした本実施形態では、レーザ強度変調周波数は、４００ｋＨｚおよびその整数倍の高調波成分８００ｋＨｚ、１．２ＭＨｚ、…とは異なる上記周波数１７０ｋＨｚなどが良い。理由については後で述べる。
【００３６】
強度変調されたＳ偏光ビーム１０２は、フォーカシングレンズ１８により、ウェハ（被対象基板）Ｗの中心近傍に集光させ、偏光ビームスプリッタ２４により低損失で反射され、１／４などの波長板２６により円若しくは楕円偏光ビーム１０３に変換した後、ガルバノミラー２５により反射され、プラズマ処理室８６の側面に設けられた観測用窓１０を通して処理室内へと導かれる。ここで、ガルバノミラー２５を回転させ、円若しくは楕円偏光ビーム１０３をウェハＷの面に平行な面内で走査することにより、ウェハ直上全面での照射（異物検出）が可能となる。
ここで、１／４などの波長板２６を設けたのは、後述するように、処理室の内壁５からの散乱反射光を偏光ビームスプリッタ２４を透過させ、処理室反射光検出用光ファイバ３３ｂで受光できるようにしたためである。
【００３７】
なお、プラズマ処理室８６の内壁５の汚染状況をモニタリングする場合には、プラズマ処理室８６の特定個所のみモニタリングできればよいので、必ずしも円若しくは楕円偏光ビーム１０３を、ウェハＷの面に平行な面内で走査する必要はない。しかし、プラズマ処理室８６の内壁５の汚染状態も、ウェハＷ上に浮遊する異物７２も同時に検出しようとすると、円若しくは楕円偏光ビーム１０３をウェハＷの面に平行な面内で走査することが望ましい。
【００３８】
そして、上記観測用窓１０の入射面を側壁と平行に形成してある場合、上記観測用窓１０からの正反射光は、ガルバノミラー２５で反射し、１／４などの波長板２６を再び通過することでＰ偏光となり、偏光ビームスプリッタ２４を透過し、散乱光検出光学系２００１で検出され、大きな雑音となる。そこで、上記観測用窓１０の入射面を傾斜面で形成することにより、この面での反射光は、検出光軸からずれて、散乱光検出光学系２００１には入射しないようにして、上記観測窓１０からの反射光による雑音を防いでいる。
【００３９】
次に、異物散乱光の検出方法について説明する。プラズマ処理室８６内へ導かれた円偏光ビーム１０３は、プラズマ中の浮遊異物７２により散乱される。該異物散乱光のうち照射円偏光ビーム１０３と同じ光軸を反対方向に伝搬する後方散乱光は、観測用窓１０を通過してガルバノミラー２５により反射され、偏光ビームスプリッタ２４へと向かう。該後方散乱光のうち、正反射成分に相当する円偏光成分は、１／４などの波長板２６を再び通過することでＰ偏光ビーム１０４となり、偏光ビームスプリッタ２４を低損失で透過し、ビームスプリッタ（分岐光学系）２７に向かう。上記Ｐ偏光ビーム１０４の大半はビームスプリッタ（分岐光学系）２７を透過して結像レンズ３１ａにより異物散乱光検出用光ファイバ３３ａの入射面に集光される。
【００４０】
図２に示すように、ウェハＷの中央位置７３ｂと検出用光ファイバ３３ａの入射面とが結像関係になっているが、入射端面の（受光領域）は、デフォーカスしたウェハ両端７３ａ、７３ｃからの散乱光も検出可能な大きさとなっている。従って、ウェハ手前から奥までの異物後方散乱光を、検出用光ファイバ３３ａによりほぼ同じ感度で検出できる。大きな受光面を確保するために、バンドルファイバやリキッドライトガイドを利用する方法が有効である。処理室内壁５で生じる散乱光は、異物散乱光検出用光ファイバ３３ａの受光面の手前（空間フィルタ３６の位置）で結像するため、該結像位置に空間フィルタ３６を設置することによって処理室の内壁５で生じる散乱光を遮光する。異物散乱光検出用光ファイバ３３ａの出射端は、レーザ光源１２の波長に設定されたモノクロメータや干渉フィルタなどの分光器３４ａに接続され、該分光器３４ａによりプラズマ発光から異物散乱光の波長成分のみを波長分離した後、フォトダイオードや光電子増倍管などの光電変換素子３５ａで光電変換される。光電変換された検出信号は、アンプ５０ａで増幅された後、ロックインアンプ５１ａにより、レーザ光の強度変調に用いた発振器１３から出力された周波数１７０ｋＨｚ、デューティ５０％の矩形波信号を参照信号として同期検波され、上記検出信号から周波数１７０ｋＨｚの異物散乱光成分を抽出する。
【００４１】
図３に示すように、プラズマ発光の強度はプラズマ励起用の高周波電力の変調周波数に同期していることを、本願発明者らは実験によって検証しており、例えば、上記４００ｋＨｚのプラズマ励起周波数の高周波電力により発生したプラズマの発光から、分光器３４により波長分離し、プラズマ励起周波数およびその整数倍と異なる上記周波数１７０ｋＨｚで変調・同期検波して得た異物信号は、図４に示すように、プラズマ発光から、波長・周波数２つの領域で分離され、検出される。この方法により、プラズマ発光から微弱な異物散乱光を感度良く検出できることを、本願発明者らは実験的に確認している。即ち、図４に示すように、プラズマ発光は、波長領域においては連続的に分布しているが、周波数領域においては、離散的に存在し、周波数領域において空き領域がある。従って、例えば波長５３２ｎｍのレーザ光を、上記プラズマ発光の周波数とは異なる、例えば周波数１７０ｋＨｚで強度変調してプラズマ処理室８６内に入射し、検出光の中から波長５３２ｎｍ成分、周波数１７０ｋＨｚ成分、すなわちピーク信号のみを取り出せば、異物からの散乱光をプラズマ発光から分離して検出することが可能なる。
【００４２】
このように、異物散乱光検出用光ファイバ３３ａの受光面の手前の結像位置に、空間フィルタ３６を設置することによって、処理室内壁５で生じる散乱光を遮光してウェハＷ上の浮遊異物からの散乱光を異物散乱光検出用光ファイバ３３ａに入射せしめることが可能となる。更に、プラズマ処理室８６に入射するレーザ光の波長および強度変調周波数を、プラズマ発光の波長および周波数と異ならしめることによって、浮遊異物からの散乱光を、プラズマ発光から分離して検出することが可能となる。
【００４３】
そして、ロックインアンプ５１ａの出力は計算機４２に送られる。計算機４２では、ガルバノドライバ２９を介して走査信号をガルバノミラー２５に送り、ビームを走査しつつ各走査位置で取り込んだ異物信号を、例えば、図５に示すような形で逐一ディスプレイ４１上に表示する。図６に示すように、計算機４２は、各検出位置において、ｎ回目の走査時の出力と（ｎ−１）回目の走査時の出力の差分をとり、ある値以上の変化のみをディスプレイ４１上に表示すると、異物信号の判定が容易となる。該表示例では、φ２００ｍｍのウェハ上の照射光５ラインでの計測結果が示されている。プラズマ中の浮遊異物により散乱光が発生した場合には、上記図６において５箇所で示した様な、パルス上の大きな信号８１ａ，８１ｂ、８１ｃ、８１ｄおよび８１ｅが現れる。計算機４２では、予め実験により得られた粒径に対する信号強度と検出された異物信号強度とを比較して異物の大きさを、また、上記パルス状の信号の数から異物個数を、また、信号が検出された時の走査位置から異物の発生位置を判定する。更に、計算機６１では、判定した異物の個数及び大きさなどから処理室内の汚染状況を判断し、異物発生総数が予め設定した基準値を超えたときはエッチング処理を終了する、汚染状況をアラームなどでプラズマ処理装置操作者に知らせる等の情報を出力することができる。
【００４４】
次に、処理室内壁散乱光の検出方法について説明する。プラズマ処理室８６内へ導かれた円若しくは楕円偏光ビーム１０３は、プラズマ処理室８６の内壁５に当たる。このとき、該プラズマ処理室８６の内壁５の表面の状態により、反射や散乱の様子が異なる。図７は、プラズマ処理室８６の内壁５の表面の状態が、凹凸の少ない平坦な状態である場合を示している。プラズマ処理室内壁５の表面の状態が凹凸の少ない平坦な状態（洗浄若しくは清掃した直後の反応生成物の付着やプラズマダメージが少なく汚染されていない状態）である場合、該プラズマ処理室８６の内壁５に当たった円若しくは楕円偏光ビーム１０３の大半は反射する。従って、ガルバノミラー２５を回転させることによってビームをウェハ面に平行な面内で走査した場合において、ビーム走査位置がウェハ中心にある場合、プラズマ処理室８６の内壁５での反射光の大半が観測用窓１０を通過してガルバノミラー２５により反射され、偏光ビームスプリッタ２４へと向かうことになる。プラズマ処理室８６の内壁５での反射光（散乱光）の大半は、正反射成分に相当する円偏光成分であるため、１／４などの波長板２６を再び通過することでＰ偏光ビーム１０５となり、偏光ビームスプリッタ２４を低損失で透過し、ビームスプリッタ（分岐光学系）２７に向かう。上記Ｐ偏光ビーム１０５の一部はビームスプリッタ２７で反射して、結像レンズ３１ｂにより処理室反射光検出用光ファイバ３３ｂの入射面（ピンホール３９の位置）に集光される。処理室反射光検出用光ファイバ３３ｂの手前における、レンズ３１ｂによってプラズマ処理室８６の内壁５とほぼ結像関係にある位置には、ピンホール（絞り）３９が設けられているため、該ピンホール３９を通過するのは、プラズマ処理室８６の内壁５からの反射光（散乱光）のみと発光強度の強いプラズマ発光の一部となる。その結果、処理室反射光検出用光ファイバ３３ｂは、プラズマ処理室８６の内壁５からの反射光（散乱光）のみと発光強度の強いプラズマ発光の一部を検出することになる。このように、処理室反射光検出用光ファイバ３３ｂには、発光強度の強いプラズマ発光の一部が入射されるため、次に説明するように、プラズマ発光の一部によって生じる信号を消去する必要がある。
【００４５】
即ち、処理室反射光検出用光ファイバ３３ｂの出射端は、レーザ光源１２の波長に設定されたモノクロメータや干渉フィルタなどの分光器３４ｂに接続されているため、該分光器３４ｂによってプラズマ発光から内壁５からの反射光の波長成分のみを波長分離した後、フォトダイオードや光電子増倍管などの光電変換素子３５ｂで光電変換される。光電変換された検出信号は、アンプ５０ｂで増幅された後、ロックインアンプ５１ｂにより、レーザ光の強度変調に用いた発振器１３から出力された周波数１７０ｋＨｚ、デューティ５０％の矩形波信号を参照信号として同期検波され、上記検出信号から周波数１７０ｋＨｚの内壁５からの反射光（散乱光）成分を抽出する。ロックインアンプ５１ｂの出力は計算機４２に送られる。計算機４２では、ガルバノドライバ２９を介して走査信号をガルバノミラー２５に送り、ビームを走査しつつ各走査位置で取り込んだ内壁５の汚染状態を示す信号を、例えば、図１３に示すような形で逐一ディスプレイ４１上に表示する。ここで、ビーム走査位置がウェハ中心からずれた場合には、プラズマ処理室８６の内壁５からの反射光の伝搬光軸が照射ビーム光軸からずれる為、散乱光検出光学系２００１にはほとんど入射しないことになる。
【００４６】
以上説明した様に、プラズマ処理室８６の内壁５の表面の状態が凹凸の少ない平坦な状態（洗浄若しくは清掃した直後の反応生成物の付着やプラズマダメージが少なく汚染されていない状態）である場合、一回のビーム走査で得られる検出信号の形状は、図９に示す様に、ウェハ中心で信号強度が大きく、ウェハ端で信号強度が小さい形状となる。
【００４７】
これに対し、プラズマ処理を進めるに従って、プラズマ処理室８６の内壁５には、反応生成物が付着したり、プラズマによるダメージが発生して汚染されていって、内壁５の表面には凹凸が発生することになる。図８は、プラズマ処理室８６の内壁５が汚染されていって表面に凹凸が発生した場合を示している。このように、内壁５が汚染されて凹凸が発生してくると、内壁５に当たった円若しくは楕円偏光ビーム１０３の大半は散乱することになる。従って、ガルバノミラー２５を回転させて、ビーム１０３をウェハ面に平行な面内で走査した場合には、プラズマ処理室８６の内壁５の表面に凹凸が増える（汚染が進む）に従って、正反射成分よりも散乱光成分が多くなり、その結果、順次図９、図１０、図１１、図１２に示す様にビーム走査位置による信号強度の違いが徐々に小さくなっていく。従って、予め、プラズマ処理室８６の内壁５の汚染状態を示す堆積した反応生成物の厚さと、ロックインアンプ５１ｂから抽出される検出位置に応じた反射（散乱）光信号のプロファイルの変化との関係を調べ、記憶装置４０に入力して記憶しておけば、計算機４２は、プラズマ処理室８６の内壁５の汚染状況をモニタリングすることができることになる。
ところで、プラズマ処理室８６の内壁５は通常円筒形を有しているため、図７に示すように汚染されていない場合には、ビーム１０３をウェハ中心からずらして照射した際、内壁５からの反射光の伝搬光軸が照射ビーム光軸からずれて、散乱光検出光学系２００１にはほとんど入射しないことになる。
【００４８】
一方、図８に示すように汚染が進んでいった場合には、ビーム１０３をウェハ中心からずらして照射した際、内壁５からより多くの散乱光が発生して、散乱光検出光学系２００１に入射して検出されることになる。
そこで、ガルバノミラー２５の回転角を検出してビーム１０３のウェハ中心からのずれ量（検出位置）を設定しておけば、予め、その設定位置における内壁５の汚染状態を示す堆積した反応生成物の厚さと、ロックインアンプ５１ｂから抽出される上記設定位置における反射（散乱）光信号の強度の変化との関係を調べ、記憶装置４０に入力して記憶しておけば、計算機４２は、プラズマ処理室８６の内壁５の汚染状況をモニタリングすることができることになる。
他方、上記プラズマ処理室８６の内壁５からの反射光（散乱光）の内、ビームスプリッタ２７を透過する透過光は、空間フィルタ３６により遮光されるため、異物散乱光検出用ファイバ３３ａには入射しないことになる。
【００４９】
以上説明したように、本第１の実施の形態によれば、上記変調・同期検波方式により、波長及び周波数２つの領域において、内壁５の汚染状態である凹凸の変化を示す散乱光の強度変化を特にプラズマ発光から分離して検出することが可能であり、内壁の汚染状態を高感度で検出することができ、その結果に基づいて、洗浄もしくは清掃等の対策を施すことによって、付着した反応生成物の剥がれ等によって生じるプラズマ中浮遊異物の発生を抑制することができる。当然、内壁５の汚染状態である凹凸の変化を示す散乱光の強度変化を浮遊異物からも分離して検出することが可能である。
【００５０】
また、本第１の実施の形態によれば、上記変調・同期検波方式により、波長及び周波数２つの領域において、微弱な異物散乱光を、プラズマ中異物検出で問題となるプラズマ発光から分離して検出することが可能であり、従来の波長分離のみの方法に比べてプラズマ中浮遊異物の検出感度が大幅に向上するという効果が得られ、従来の波長分離のみの場合に得られる最小検出感度は、せいぜいφ１μｍ程度が限界であったのに対し、本実施の形態の方法によれば、最小検出感度をφ０．２μｍ程度にまで向上でき、ウェハ全面にわたり安定な異物検出が可能になるという効果も得られる。さらに、ウェハ上全面で異物検出を行って、異物の個数、大きさ、分布を判定するので、操作者は、その情報を、例えば、ディスプレイ４１上でリアルタイムで確認することもできる。
【００５１】
また、本第１の実施の形態によれば、プラズマを発光させた状態で、処理室の内壁の汚染状態をモニタリングできるため、早期に洗浄や清掃等の対策を施して突発的多量浮遊異物の発生を抑制して歩留まりを向上させることが可能となる。また、本第１の実施の形態によれば、プラズマを発光させた状態で、検出される浮遊異物の発生個数、大きさ、分布の情報をもとに、処理室内の汚染状況をリアルタイムで判断できるため、例えば、クリーニング時期の最適化による装置稼働率の向上、突発的大量異物の発生の早期発見ができ、歩留まりが向上する。
【００５２】
また、本第１の実施の形態によれば、処理室内の汚染状況を常にモニタしながら処理を進められるため、このようにして製造された半導体基板や液晶基板は、基準値以上の異物を含まない環境で製造された、高品質で、信頼性の高い製品となる。
また、本第１の実施の形態によれば、ダミーウェハを用いた処理室の汚染状況判断や、抜き取り検査による汚染状況判断の頻度低減が可能であるため、ダミーウェハのコスト削減がなされる。
【００５３】
次に、本発明に係る第２の実施の形態を、図１４〜図１５に基づいて説明する。図１４は、本第２の実施の形態に係る、処理室内壁汚染状況モニタリング機能付きプラズマ中浮遊異物計測装置をもつエッチング処理装置の構成を示す図である。
【００５４】
処理室内壁汚染状況モニタリング機能付きプラズマ中浮遊異物計測装置は、主としてレーザ照明光学系２０００と散乱光検出光学系２００２と制御・信号処理系６００１とにより構成され、レーザ照明光学系２０００と散乱光検出光学系２００２における照明光出口部・検出光入口部は、プラズマ処理室８６の側面に設けられた観測用窓１０に対向するように配置されている。
【００５５】
本第２の実施の形態において、前記第１実施形態と異なる点は、プラズマ処理室８６の内壁５からの反射（散乱）光の検出をＣＣＤカメラ等の撮像素子３３ｃで行い、プラズマ処理室８６の内壁５の汚染状況の判定を、該ＣＣＤカメラ等の撮像素子３３ｃで得られた画像から判断する点である。すなわち、プラズマ処理室８６の内壁５の表面の凹凸状態によって、発生するスペックルパターンが変化するため、該スペックルパターンを図１５に示すように撮像素子３３ｃで撮像し、該撮像された画像信号を基に検出されるスペックルパターンの変化から、内壁５の表面状態の微妙な変化を検出することができる。洗浄若しくは清掃した直後から反応生成物が付着したり、プラズマダメージが生じてきて汚染が進むと、内壁５の表面の状態が平坦な状態から凹凸状態が増大するように変化していき、スペックルパターンがない状態から増大していくことになる。そこで、内壁５の結像位置に受光面を設置した撮像素子３３ｃで内壁５の表面から反射してくる画像を撮像し、該撮像された画像信号を計算機４２で画像処理（例えば２次元方向に微分処理（ラプラシアンフィルタリング処理））することによってスペックルパターンの変化（例えばスペックルパターンの濃淡の変化）として内壁５の汚染状態を検出することができることになる。しかしながら、プラズマ発光の光については、撮像素子３３ｃに入射されないように波長フィルタ等のフィルタ４５でフィルタリングする（遮光する）ことが必要となる。
【００５６】
以上説明したように、本第２の実施の形態によれば、本第１の実施の形態と同様の効果を得られる他、プラズマ処理室の内壁５の表面の状態を画像として残すことが可能となる。
【００５７】
また、上記第１および第２の実施の形態において、特開平１１−２５１２５２号公報に示されているような側方散乱光検出光学系と併用することも可能である。
【００５８】
以上説明したように、処理室の内壁の汚染状況の計測結果、および／またはプラズマ中若しくはその近傍に浮遊する異物の計測結果について診断ユニット（４２であってもよく、他の製造ライン管理装置でもよい）が診断して、処理室の内壁や電極の側壁への反応生成物の付着を低減する制御手段（例えば処理室の内壁や電極の側壁の温度を制御する手段や処理室の内壁に沿って磁界を発生させる手段）３７（図１及び図１４に示す。）にフィードバックして該制御手段３７を制御することによって、処理室内への反応生成物の付着を低減することができる。また、診断ユニットが、診断結果に基づいて被処理基板を製造ラインから排除することもでき、さらにクリーニング指示を出して被処理基板の投入を中止してクリーニングを実行してもよい。
【００５９】
また、本発明の実施の形態によれば、プラズマ中浮遊異物の最小検出感度をφ０．２μｍ程度にまで向上でき、ウェハ全面にわたり安定な異物検出が可能になり、しかも異物の発生個数、大きさ、分布の情報をもとに、処理室内の汚染状況をリアルタイムで判断できると同時に処理室内壁の汚染状況をモニタリングできるため、例えば、クリーニング時期の最適化による装置稼働率の向上、突発的大量異物の発生の早期発見ができ、歩留まりが向上する。また、処理室内の汚染状況を常にモニタしながら処理を進められるため、このようにして製造された半導体基板や液晶基板は、基準値以上の異物を含まない環境で製造された、高品質で、信頼性の高い製品となる。
【００６０】
また、本実施形態によれば、ダミーウェハを用いた処理室の汚染状況判断や、抜き取り検査による汚染状況判断の頻度低減が可能であるため、ダミーウェハのコスト削減がなされる。
【００６１】
これらの効果により、エッチング処理室内の汚染状況のリアルタイムモニタリングが可能となり、付着異物のよる不良ウェハの発生を低減でき、高品質の半導体素子の製造が可能になるという効果と、装置クリーニング時期を正確に把握することができるという効果が生まれる。
【００６２】
また、ダミーウェハを用いた異物の先行作業チェック作業の頻度が低減できるため、コストの低減と生産性の向上という効果が生まれる。また、製造ラインの自動化も可能となるという効果も有している。
【００６３】
次に、本発明の第３の実施の形態を、図１６、図１７及び図１８に基づいて説明する。先ず、図１６及び図１７を用いて、本発明における半導体集積回路の製造方法の概念を説明する。
【００６４】
工程１００ａは、ウェハＷ上にシリコン酸化膜などの被加工膜６０１を形成する成膜工程であり、工程１００ｂは、形成した膜の厚さを検査する膜厚計測工程である。工程１００ｃは、ウェハＷにレジスト６０２を塗布する、レジスト塗布工程であり，工程１００ｄは、マスクパターン６０３をウェハ上に転写するパターン転写工程である。工程１００ｅは、被加工部のレジストを除去する、現像工程であり、工程１００ｆは、レジストパターン６０４をマスクとして、レジスト除去部６０５の被加工膜６０１をエッチングし配線溝やコンタクトホール６０６を形成する、エッチング工程である。工程１００ｈは、レジストパターン６０４を除去する、アッシング工程であり、工程１００ｉは、ウェハ表面や裏面を洗浄する、洗浄工程である。上記一連の工程は、例えば、コンタクトホールの形成に適用される。
【００６５】
次に、図１８を用いて、エッチング中に発生した異物がウェハに付着することで生じる欠陥について説明する。図１８は、例えば、コンタクトホールエッチングにおいて発生する欠陥の例を示す図である。
異物７０１は、エッチングの最中にコンタクトホール開口部に付着した異物を示している。この場合、付着異物によりエッチング反応停止するため、該異物付着部分のコンタクトホールは非開口となり、致命欠陥となる。
異物７０２は、エッチングの最中にコンタクトホール内部に付着した異物を示している。この場合も、付着異物によりエッチング反応停止するため、該異物付着部分のコンタクトホールは非開口となり、致命欠陥となる。
【００６６】
異物７０３および異物７０４は、エッチング終了後にコンタクトホール内部に付着した異物を示している。コンタクトホールのようなアスペクト比の高い箇所に付着した異物は、洗浄しても取り除くことが困難な場合が多く、異物７０３のように、その大きさが大きい場合には、コンタクト不良が生じるため致命欠陥となる。
異物７０５は、エッチングの最中にレジストパターン６０４に付着した異物を示している。この場合、該付着異物７０５によりエッチング反応は何ら影響を受けることはなく、該付着異物７０５により致命欠陥が発生することはない。
このように、異物が付着しても、異物の大きさが欠陥を引き起こすほど大きくない場合や、付着箇所が非エッチング領域であるような場合には致命欠陥とならず、ウェハに異物が付着してもその全てが致命欠陥を引き起こすわけではない。また、異物７０１や異物７０５が、洗浄により比較的除去しやすい異物であるのに対し、異物６０２、異物７０３および異物７０４のように、高アスペクト比のコンタクトホールに落下した異物は、洗浄による除去が困難である。
【００６７】
さて、本発明では、エッチング工程１００ｆにおいて、プラズマ中浮遊異物計測装置１１００により、エッチング中に処理室内に発生した異物をリアルタイムで検出し、該異物検出結果に基づき、処理したウェハを次の工程に送り順次残りのウェハの処理を進めるか、次の工程に送る前に外観検査を行うか、処理を中止し処理室内のクリーニング（メンテナンス）を行うかを選択する。
【００６８】
ここでは、検出異物大きさおよび個数と予め設定した規格値（異物管理基準）とを比較することで、次に行う処理を選択した。
そこで、次に、本実施例における上記規格値（異物管理基準）の算出方法の例を説明する。既に説明したとおり、ウェハに異物が付着してもその全てが致命欠陥を引き起こすわけではない。付着異物により致命欠陥が発生する確率は、エッチングパターンの開口率やパターン密度、更には配線幅などと、付着する異物の大きさや個数の関係から、計算により求めることができる。したがって、エッチング処理中に検出される異物の大きさと個数と、ウェハ付着異物の大きさと個数の相関関係を、予め実験によって求めておくことで、エッチング中に検出した異物により致命欠陥が引き起こされる確率を求めることができる。
【００６９】
規格値（異物管理基準）は、上記手段により求めた値に基づいて設定する。以下に、本実施例における、規格値の設定例を示す。
規格値１は、検出異物のうちある大きさ以上の個数が該規定値１より少なければ、致命欠陥が発生する確率が非常に低くなるように（例えば、致命欠陥発生確率１％程度以下）設定する。例えば、規格値１は、異物粒径０．４μｍ以上１０個とする。
規格値２は、検出異物のうちある大きさ以上の個数が上記規格値１以上で該規定値２より少なければ、致命欠陥の発生が懸念される値となるように（例えば、致命欠陥発生確率５％程度以下）設定する。例えば、規格値２は、異物粒径０．４μｍ以上３０個とする。
検出異物のうちある大きさ以上の個数が該規定値２以上であると、致命欠陥が多数発生する（例えば、致命欠陥発生確率５％程度以上）ことになる。
上記規格値に基づき、エッチング処理中に検出された異物のうちある大きさ以上の個数が上記規定値１より少ない場合には、致命欠陥の発生する確率が低いので、引き続き次のウェハの処理を行う。
【００７０】
エッチング処理中に検出された異物のうちある大きさ以上の個数が上記規定値１以上であるが、上記規定値２よりは少ない場合には、エッチング処理終了後、外観検査をう。該外観検査の結果、致命欠陥が確認されなければ、該ウェハは次のアッシング工程１００７に送る。該外観検査の結果、致命欠陥が確認された場合は、該致命欠陥が救済可能な欠陥か判定する。上記判定結果に基づき、救済可能（救済回路の利用など）な欠陥と判定された場合は、該ウェハは次のアッシング工程１００ｈに送る。上記判定結果に基づき、救済不可能な欠陥と判定された場合は、該欠陥個所を記録した後、該ウェハを次のアッシング工程１００ｈに送る。その後、例えば、ダイシングにより各チップ毎にきり出した時に、該救済不可能な欠陥を含むチップは排除する。
【００７１】
エッチング処理中に検出された異物のうちある大きさ以上の個数が、上記規定値２より多い場合には、その後に処理を行うウェハにも、大量の致命欠陥が発生する可能性が高いので、エッチング処理を中断しプラズマ処理室内のクリーニング（メンテナンス）を行うよう、エッチング装置の操作者にモニタ画面上に表示したりアラームで知らせたりする。
【００７２】
プラズマ中浮遊異物計測装置を備えないエッチング処理装置では、必ずしも適切な時間で処理室のクリーニングが行われない。従って、本来クリーニングしなくても良い時期にクリーニングを行い、装置稼働率を低下させたり、逆にクリーニングすべき時期を過ぎているにもかかわらず処理を続け、不良品を大量に生じさせ歩留まりを低下させることもある。
また、処理室内異物チェックのためのダミーウェハによる先行作業を行い、その結果からクリーニング時期を決める方法もある。この場合、一連の工程中に余分な作業が入るため、スループットが低下し、ダミーウェハ分のコストが必要とされた。しかし、ウェハの大口径化に伴い、ダミーウェハのコストの増加は必至で、処理室内異物チェックのためのダミーウェハによる先行作業の削減も大きな問題になっている。
【００７３】
これに対し本実施の形態によれば、処理室内の汚染状況をリアルタイムでモニタしながら被処理体の処理を行えるため、クリーニング時期の最適化が図られ、ダミーウェハによる先行作業も必要ないため、スループットが向上し、ダミーウェハのコスト削減が可能となる。また、本実施の形態の工程により製造された製品は、規定値以上の異物を含まない良質の製品、したがって信頼性の高い製品を製造することができる。
【００７４】
なお、以上の実施の形態においては、エッチング処理装置への適用例について述べたが、先にも記載したように、本発明の適用範囲はこれに限定されるものではなく、例えば、本発明をアッシング装置や成膜装置に適用することで、アッシング装置内および成膜装置内の異物のリアルタイムモニタリングが可能となり、以って、ホトリソグラフィ工程中のアッシング工程および成膜工程起因の不良を低減することが可能となり、不良品の発生防止と歩留まりの向上とを図ることができる。
【００７５】
【発明の効果】
本発明によれば、プラズマ処理室内壁の汚染状況をモニタリングすることができるため、事前に対策が施されて多量に異物が発生するのを防止して、歩留まり向上を図れると共に高品質の半導体素子の製造が可能になり、しかも装置クリーニング時期を正確に把握することができる効果が得られる。
また、本発明によれば、構成を簡単にして、プラズマ処理室内壁の汚染状況のモニタリングとプラズマ中浮遊異物のモニタリングとを行うことができる効果を奏する。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態に係る、処理室内壁汚染状況モニタリング機能付きプラズマ中浮遊異物計測装置をもつエッチング処理装置の構成を示す図である。
【図２】本発明の第１の実施の形態における、異物散乱光及び処理室内壁反射（散乱）光検出のための光学系を単純化した説明図である。
【図３】プラズマ励起周波数とプラズマ発光が同期している様子を示す説明図である。
【図４】異物散乱光のプラズマ発光からの波長・周波数分離の様子を示す説明図である。
【図５】本発明の第１の実施の形態における、ウェハ上５点での検出光強度の時間変化を示す図である。
【図６】本発明の第１の実施の形態における、ウェハ上５点での異物信号強度の時間変化を示す図である。
【図７】本発明の第１の実施の形態における、処理室内壁での照射レーザ光の反射の様子を示す図である。
【図８】本発明の第１の実施の形態における、処理室内壁での照射レーザ光の散乱の様子を示す図である。
【図９】本発明の第１の実施の形態における、処理室内壁反射（散乱）光信号強度のプロファイルを示す図である。
【図１０】本発明の第１の実施の形態における、処理室内壁反射（散乱）光信号強度のプロファイルを示す図である。
【図１１】本発明の第１の実施の形態における、処理室内壁反射（散乱）光信号強度のプロファイルを示す図である。
【図１２】本発明の第１の実施の形態における、処理室内壁反射（散乱）光信号強度のプロファイルを示す図である。
【図１３】本発明の第１の実施の形態における、処理室内壁反射（散乱）光信号強度のプロファイルの時間変化を示す図である。
【図１４】本発明の第２の実施の形態に係る、処理室内壁汚染状況モニタリング機能付きプラズマ中浮遊異物計測装置をもつエッチング処理装置の構成を示す図である。
【図１５】本発明の第２の実施の形態に係る、処理室内壁反射（散乱）光画像を示す図である。
【図１６】本発明の第３の実施の形態に係る、プラズマ中浮遊異物計測装置付きエッチング処理装置を導入した、半導体集積回路装置の製造工程を、処理の流れに沿って模式的に示した説明図である。
【図１７】本発明の第３の実施の形態に係る、コンタクトホールの形成過程を、断面構造を用いて、処理の流れに沿って模式的に示した説明図である。
【図１８】本発明の第３の実施の形態に係る、コンタクトホールのエッチング工程において、付着異物による生じる欠陥の例を、模式的に示した説明図である。
【符号の説明】
５…内壁、１０…観測用窓、１２…レーザ光源、１３…発振器、１４…ＡＯ変調器、１８…フォーカシングレンズ、２４…偏光ビームスプリッタ、２６…１／４などの波長板、２７…ビームスプリッタ（分岐光学系）、２９…ガルバノドライバ、３１ａ、３２ｂ…結像レンズ、３３ａ…異物散乱光検出用光ファイバ、３３ｂ…処理室反射光検出用光ファイバ、３３ｃ…撮像素子（ＣＣＤカメラ）、３４ａ、３４ｂ…分光器、３５ａ、３５ｂ…光電変換素子、３６…空間フィルタ、３９…絞り（ピンホール）、４０…記憶装置、４１…デイスプレイ、４２…計算機、４５…フィルタ、５０ａ，５０ｂ…アンプ、５１ａ，５１ｂ…ロックインアンプ、８３…シグナルジェネレータ、８４…パワーアンプ、８５…分配器、８６…プラズマ処理室、８１…上部電極、８２…下部電極、７１…プラズマ、Ｗ…半導体基板（被処理基板）、１００ａ…成膜工程、１００ｂ…膜厚計測工程、１００ｃ…レジスト塗布工程、１００ｄ…パターン転写工程、１００ｅ…現像工程、１００ｆ…エッチング工程、１００ｇ…異物判定部、１００ｈ…アッシング工程、１００ｉ…洗浄工程、２０００…レーザ照明光学系、２００１…散乱光検出光学系、６０００…制御・信号処理系。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor such as a semiconductor substrate or a liquid crystal substrate and an apparatus therefor, and in particular, a foreign substance floating in a processing chamber (vacuum processing chamber) that performs processing such as thin film generation (film formation) or etching, The present invention also relates to a semiconductor manufacturing method, a process processing method, and an apparatus therefor having a function of measuring in-situ the contamination status of a processing chamber.
[0002]
[Prior art]
Starting with an etching apparatus, a process using plasma is widely applied to a semiconductor manufacturing process and a liquid crystal display substrate manufacturing process.
[0003]
As described above, in a processing apparatus using plasma, reaction products generated by, for example, etching reaction due to plasma processing are deposited on the wall surface or electrode of the plasma processing chamber, and are peeled off as time passes to form floating foreign substances. It is known to be. This floating foreign substance falls on the wafer and becomes a foreign substance attached at the moment when the etching process is finished and the plasma discharge is stopped, causing a circuit characteristic defect and a pattern appearance defect. Ultimately, this causes a decrease in yield and a decrease in device reliability.
[0004]
A number of devices for inspecting foreign matter adhering to the surface of a substrate such as the wafer have been reported and put into practical use, but these are used to inspect the substrate once extracted from the plasma processing apparatus. When it is determined that a large number of wafers are generated, processing of other wafers has already progressed, and there is a problem of a decrease in yield due to a large number of defects. Further, in the evaluation after the processing, the distribution of the generation of foreign matters in the processing chamber and the change with time are not known. Accordingly, there is a demand in the fields of semiconductor manufacturing, liquid crystal manufacturing, and the like for techniques for real-time monitoring of the contamination status in the processing chamber in-situ.
[0005]
The size of foreign matter floating in the processing chamber is in the range of submicron to several hundreds of μm, but in the field of semiconductors that are highly integrated into 256 Mbit DRAM (Dynamic Random Access Memory) and 1 Gbit DRAM, The minimum line width is 0.25 to 0.18 [mu] m and is continuously miniaturized, and the size of foreign matter to be detected is also required to be on the order of submicrons.
[0006]
As conventional techniques for monitoring foreign matter floating in a processing chamber (vacuum processing chamber) such as a plasma processing chamber, Japanese Patent Laid-Open Nos. 57-118630 (prior art 1) and Japanese Patent Laid-Open No. 3-25355 (prior art 2). ), JP-A-3-147317 (conventional technology 3), JP-A-6-82358 (conventional technology 4), JP-A-6-124902 (conventional technology 5), JP-A-10-213539 (conventional technology). Technology 6), Japanese Patent Application Laid-Open No. 11-251252 (Conventional Technology 7), and Japanese Patent Application Laid-Open No. 11-330053 (Conventional Technology 8).
[0007]
The prior art 1 includes means for irradiating the reaction space with parallel light having a spectrum different from the spectrum of the self-emission light in the reaction space, and scattering from fine particles generated in the reaction space upon receiving the parallel light irradiation. A vapor deposition apparatus provided with a means for detecting light is disclosed.
[0008]
Further, in the above conventional technique 2, in a fine particle measuring apparatus that measures fine particles adhering to the surface of a semiconductor device substrate and floating fine particles using scattering by laser light, the wavelength is the same and the mutual position is low. A laser beam phase modulation unit that generates two laser beams modulated at a predetermined frequency having a phase difference, and an optical system that intersects the two laser beams in a space including the fine particles to be measured; A light detection unit that receives light scattered by the fine particles to be measured in the intersected region of the two laser beams and converts the light into an electric signal, and the laser beam phase in the electric signal by the scattered light A fine particle measuring apparatus comprising: a signal processing unit that extracts a signal component having the same or twice the frequency as the phase modulation signal in the modulation unit and a phase difference from the phase modulation signal that is constant in time. It is shown.
[0009]
The prior art 3 includes a step of generating light scattered in the reaction container by scanning irradiation with coherent light, and a step of detecting light scattered in the reaction container. A technique for measuring the contamination state in the reaction vessel by analyzing the scattered light is described.
[0010]
The prior art 4 includes laser means for generating laser light, scanner means for scanning a region in a reaction chamber of a plasma processing tool containing particles to be observed with the laser light, and particles in the area. A particle detector is described having a video camera for generating a video signal of scattered laser light and means for processing and displaying an image of the video signal.
[0011]
Further, the conventional technique 5 includes a camera device for observing a plasma generation region in the plasma processing chamber, a data processing unit for processing images obtained by the camera device to obtain target information, and the data processing unit. A plasma processing apparatus comprising: a control unit that controls at least one of exhaust means, process gas introduction means, high-frequency voltage application means, and purge gas introduction means so as to reduce particles based on the information obtained in Are listed.
[0012]
The prior art 6 also includes a light transmitter for transmitting a light beam that irradiates across the measurement volume, a light detector and scattered light from the measurement volume and condensing the light to the light detector. And a detector configured to generate a signal representative of the intensity of light directed to the photodetector and to analyze the signal from the photodetector. Connected to a pulse detector for detecting a pulse in the signal from the light detector, and corresponding to the particle by the particle associated with multiple irradiations of the beam while the particle moves through the measurement volume. A particulate sensor is described that includes signal processing means including an event detector that identifies a series of pulses due to scattered light.
[0013]
Further, in the prior art 7, in a plasma processing apparatus that generates plasma in a processing chamber and processes an object to be processed with the plasma, light having a desired wavelength and intensity modulated at a desired frequency is emitted. From the irradiation optical system that irradiates the processing chamber, the scattered light detection optical system that separates the scattered light obtained from the processing chamber with the desired wavelength component, converts it into a signal, and the scattered light detection optical system. A plasma floating device comprising: a foreign substance signal extracting means for extracting a signal indicating a foreign substance floating in or near the plasma from the obtained signal by separating the intensity-modulated desired frequency component from the obtained signal and detecting it separately from the plasma. It is disclosed that a foreign object measuring device is provided.
[0014]
Further, in the above conventional technique 8, in a plasma processing apparatus that generates plasma in a processing chamber and processes an object to be processed with the plasma, a plurality of wavelengths having mutually different wavelengths and intensity-modulated at a desired frequency are provided. Obtained from the irradiation optical system for irradiating the beam into the processing chamber, the scattered light detection optical system that separates the scattered light into different wavelength components and converts them into a plurality of signals, and the scattered light detection optical system Foreign substance signal extraction means for separating and detecting a plurality of signals indicating foreign substances floating in or near the plasma by extracting the desired frequency components whose intensity has been modulated from the plurality of signals is provided. It is disclosed that a plasma floating foreign material measuring apparatus is provided.
[0015]
[Problems to be solved by the invention]
In the above conventional techniques 1 to 6, the laser beam is irradiated from the observation window provided on the side surface of the plasma processing chamber, and is different from the laser irradiation observation window provided on the opposite side surface or the other side surface. Laser forward scattered light and side scattered light are detected from the window. Therefore, in the method for detecting the forward scattered light and the side scattered light, the irradiation optical system and the detection optical system are formed by different units, and two observation windows for attaching them are necessary. Axis adjustment and the like must also be performed by the irradiation / detection optical system, and handling is troublesome.
[0016]
Usually, an observation window on the side of a processing chamber such as a plasma processing chamber is provided in most models for monitoring plasma emission, etc., but only one observation window is provided. Not a few. Therefore, there is a problem that the conventional method that requires two observation windows cannot be applied to a manufacturing apparatus having a processing chamber that has only one observation window.
[0017]
Furthermore, in the conventional method for detecting the forward scattered light and the side scattered light, the irradiation beam irradiated to the plasma processing chamber is rotationally scanned to try to observe the occurrence of foreign matter on the entire surface of the substrate to be processed such as a wafer. In some cases, a large number of observation windows and detection optical systems are required, which causes a significant cost increase. In addition, the provision of a large number of observation windows and detection optical systems is actually very limited due to space factor limitations. Expected to be difficult.
[0018]
On the other hand, in the field of semiconductors that have been highly integrated into 256 Mbit DRAMs, and further to 1 Gbit DRAMs, the minimum line width of circuit patterns has been continually miniaturized to 0.25 to 0.18 μm, and the size of foreign matter to be detected Submicron orders are also required. However, in the related arts 1 to 6, since it is difficult to separate the foreign matter scattered light and the plasma emission, the application is limited to observation of a relatively large foreign matter, and it is difficult to detect a sub-micron-order fine foreign matter. Conceivable.
[0019]
Further, although the prior arts 7 and 8 describe detecting foreign matter floating in or near the plasma, consideration is given to detecting a contamination state adhering or depositing on the inner wall of the plasma processing chamber. Was not.
[0020]
The first object of the present invention is to solve the above-mentioned problems, and it is possible to detect the contamination state of the inner wall of the plasma processing chamber in a plasma processing apparatus such as etching, sputtering, CVD, etc., and many foreign matters are generated on the substrate to be processed. An object of the present invention is to provide a semiconductor manufacturing method, a plasma processing method, and an apparatus therefor, which can prevent the occurrence of a large number of defects by taking measures such as cleaning at an early stage.
[0021]
A second object of the present invention is to detect the contamination of the inner wall of the plasma processing chamber, and also to detect foreign matters floating in the plasma processing chamber, so that many foreign matters are generated on the substrate to be processed. It is an object of the present invention to provide a semiconductor manufacturing method, a plasma processing method, and an apparatus therefor, which can prevent the occurrence of a large number of defects by taking measures to prevent the occurrence of such defects.
[0022]
In addition, a third object of the present invention is to provide a plasma processing method and apparatus for compacting an irradiation / detection optical system for detecting a contamination state of an inner wall or a floating foreign material so that it can be mounted in a limited narrow space. Will provide.
[0023]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a semiconductor manufacturing method, a plasma processing method and an apparatus for manufacturing a semiconductor by generating plasma in a processing chamber and processing a semiconductor substrate by the generated plasma. An irradiation step of irradiating the processing chamber with a light beam through the observation window, and a reflected light image in which the irradiation step causes a change in accordance with a change in unevenness from the inner wall of the processing chamber (deposition of a reaction product, damage, etc.) Of the processing chamber calculated based on a detection step in which an image is formed by an imaging optical system through an observation window, received by a detector and detected as a light reception signal, and a change in the light reception signal detected by the detection step And a control step of controlling plasma processing on the semiconductor substrate based on the contamination state of the inner wall.
[0024]
The present invention also relates to a semiconductor manufacturing method, a plasma processing method, and an apparatus for manufacturing a semiconductor by generating plasma in a processing chamber and processing a semiconductor substrate by the generated plasma, and intensity modulation at a desired frequency. An irradiation step of irradiating the processed beam into the processing chamber through the observation window, and a reflected light image that changes in accordance with a change in the uneven state from the inner wall of the processing chamber irradiated by the irradiation step through the observation window. An image formed by the system, received by a detector and detected as a light reception signal, and a signal indicating a change in the concavo-convex state of the inner wall of the processing chamber is extracted by extracting the intensity modulation frequency component from the detected light reception signal. A detection step of detecting separately from the plasma, and the processing calculated based on a change in the signal detected by the detection step Characterized in that based on the pollution of the inner wall of a control step of controlling a plasma process on the semiconductor substrate.
[0025]
Further, the present invention is characterized in that, in the detection step, the optical image formed by the imaging optical system and received by the detector is a speckle pattern image.
According to the present invention, in the detection step, when the reflected light image is imaged by an imaging optical system through an observation window and received by a detector, light generated from plasma in the processing chamber is blocked by a filter. It is characterized by.
Further, the present invention is characterized in that, in the irradiation step, when the beam is irradiated into the processing chamber, the beam is scanned so that a plurality of positions on the inner wall of the processing chamber can be irradiated.
[0026]
Further, the present invention is characterized in that the observation window for irradiating the beam in the irradiation step and the observation window for passing the reflected light image in the detection step are the same.
Further, the present invention is characterized in that, in the detecting step, a light image limited by a diaphragm installed at an image forming position of the image forming optical system is received by a detector.
[0027]
The present invention also relates to a semiconductor manufacturing method, a plasma processing method, and an apparatus for manufacturing a semiconductor by generating plasma in a processing chamber and processing a semiconductor substrate by the generated plasma, and intensity modulation at a desired frequency. An irradiation step of irradiating the processing chamber through the observation window with the irradiated beam, and a reflected light image obtained through the observation window from the inside of the processing chamber by the irradiation step is branched by a branching optical system, and the one of the branched reflections An optical image is formed by a first imaging optical system, received by a first detector, converted into a first received light signal, and the intensity-modulated frequency component from the converted first received light signal. The first signal indicating the foreign substance floating in or near the plasma is separated and detected from the plasma, and the other reflected reflected light image is detected as the second reflected light image. Processing is performed by forming an image with an imaging optical system, receiving the light with a second detector, detecting it as a second received light signal, and extracting the intensity modulation frequency component from the detected second received light signal. A detection step in which a second signal indicating a change in the uneven state of the inner wall of the chamber is detected separately from the plasma, and in the plasma calculated based on the first signal detected in the detection step Control for controlling plasma processing on the semiconductor substrate based on the occurrence of foreign matter floating in the vicinity or the contamination of the inner wall of the processing chamber calculated based on the change in the second signal detected in the detection step And a step.
Further, the present invention is characterized in that a diaphragm is provided at an image forming position of the second image forming optical system to limit and reduce light from foreign matter or plasma.
Further, the present invention is characterized in that a spatial filter is installed at an image forming position of the first image forming optical system to block scattered reflected light from the inner wall of the processing chamber.
[0028]
Further, the present invention determines the contamination status of the inner wall of the processing chamber in advance in relation to the surface state (unevenness state) of the processing chamber wall due to adhesion of reaction products to the processing chamber wall and / or plasma damage. This is performed by comparing and determining an experimentally obtained signal and the received light signal.
In addition, the present invention is based on the relationship between the thickness of the reaction product attached to the processing chamber wall and the signal obtained experimentally in advance and the thickness of the coating film, simultaneously with the determination of the contamination status of the inner wall of the processing chamber. The film thickness of the attached reaction product is obtained.
In addition, the present invention is characterized in that the state of contamination of the inner wall of the processing chamber and floating foreign substances are discriminated from the number, size, and distribution and displayed on the display.
[0029]
As described above, according to the present invention, it is possible to always grasp the contamination state of the inner wall of the processing chamber, thereby predicting that a large amount of floating foreign matters are generated at an early stage and controlling the plasma processing on the substrate to be processed. (By taking various measures such as stopping the loading of the substrate to be processed and executing the cleaning, and monitoring the process processing conditions), the occurrence of large numbers of defects is prevented and the yield is remarkably improved. Can be made.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments according to the present invention will be described with reference to FIGS.
[0031]
In each embodiment of the present invention described below, an example of application to a parallel plate plasma etching apparatus used in a plasma dry etching apparatus is shown, but the scope of application of the present invention is not limited to this. In addition, the present invention can be applied to thin film generation (film formation) apparatuses such as sputtering apparatuses and CVD apparatuses, or various thin film generation and processing apparatuses such as ECR etching apparatuses, microwave etching apparatuses, and ashing apparatuses. .
[0032]
First, a first embodiment according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a configuration of a plasma etching processing apparatus having a plasma floating particle measuring apparatus with a processing chamber wall contamination status monitoring function according to the first embodiment. That is, the first embodiment according to the present invention is to provide a measuring device capable of monitoring the contamination state of the processing chamber wall in various processing devices such as etching and ashing.
[0033]
As shown in FIG. 1, in the etching processing apparatus, the output voltage of the power amplifier 84 is modulated by the high frequency signal from the signal generator 83, and this high frequency voltage is distributed by the distributor 85 to be parallel to each other in the plasma processing chamber 86. Is applied between the upper electrode 81 and the lower electrode 82, and plasma 71 is generated from the etching gas by discharge between both electrodes, and a semiconductor substrate (wafer) W as an object to be processed is produced by the active species. Etch. For example, 400 kHz is used as the high-frequency signal.
[0034]
The processing chamber wall contamination status monitoring function-equipped floating foreign matter measuring apparatus 2 mainly includes a laser illumination optical system 2000, a scattered light detection optical system 2001, and a control / signal processing system 6000. The illumination light exit portion and the detection light entrance portion in the scattered light detection optical system 2001 are arranged so as to face the observation window 10 provided on the side surface of the plasma processing chamber 86.
[0035]
In the laser illumination optical system 2000, first, an S-polarized beam 101 emitted from a laser light source (for example, wavelength 532 nm) 12 is incident on an AO (Acousto-Optical) modulator 14. Based on the control signal from the computer 42, for example, a rectangular wave signal having a frequency of 170 kHz, preferably a duty of 50%, is applied to the AO polarizer 14 to modulate the intensity of the S-polarized beam at the above frequency. . Here, in the present embodiment in which the high-frequency voltage applied to the electrode of the etching processing apparatus is 400 kHz, the laser intensity modulation frequency is 400 kHz, and the above-mentioned frequency 170 kHz, which is different from the harmonic components 800 kHz, 1.2 MHz,. Etc. are good. The reason will be described later.
[0036]
The intensity-modulated S-polarized beam 102 is condensed near the center of the wafer (target substrate) W by the focusing lens 18, reflected by the polarization beam splitter 24 with low loss, and by a wave plate 26 such as ¼. After being converted into a circular or elliptically polarized beam 103, it is reflected by the galvanometer mirror 25 and guided to the processing chamber through the observation window 10 provided on the side surface of the plasma processing chamber 86. Here, by rotating the galvanometer mirror 25 and scanning the circular or elliptically polarized beam 103 in a plane parallel to the plane of the wafer W, irradiation (foreign matter detection) can be performed on the entire surface immediately above the wafer.
Here, the wavelength plate 26 such as ¼ is provided, as will be described later, the scattered reflected light from the inner wall 5 of the processing chamber is transmitted through the polarization beam splitter 24 and the processing chamber reflected light detecting optical fiber 33b. This is because it is possible to receive light with.
[0037]
When monitoring the contamination state of the inner wall 5 of the plasma processing chamber 86, it is only necessary to monitor a specific portion of the plasma processing chamber 86. Therefore, the circular or elliptically polarized beam 103 is not necessarily in a plane parallel to the surface of the wafer W. There is no need to scan with. However, if the contamination state of the inner wall 5 of the plasma processing chamber 86 and the foreign material 72 floating on the wafer W are simultaneously detected, the circular or elliptically polarized beam 103 can be scanned in a plane parallel to the surface of the wafer W. desirable.
[0038]
When the incident surface of the observation window 10 is formed in parallel with the side wall, the specularly reflected light from the observation window 10 is reflected by the galvanometer mirror 25 and the wavelength plate 26 such as ¼ is again formed. By passing through, it becomes P-polarized light, passes through the polarization beam splitter 24, is detected by the scattered light detection optical system 2001, and becomes a large noise. Therefore, by forming the incident surface of the observation window 10 as an inclined surface, the reflected light on this surface is shifted from the detection optical axis so as not to enter the scattered light detection optical system 2001, and the observation window 10. Noise due to reflected light from the window 10 is prevented.
[0039]
Next, a method for detecting foreign matter scattered light will be described. The circularly polarized beam 103 guided into the plasma processing chamber 86 is scattered by the floating foreign material 72 in the plasma. Backscattered light propagating in the opposite direction along the same optical axis as the irradiated circularly polarized beam 103 among the scattered light from the foreign matter passes through the observation window 10 and is reflected by the galvanometer mirror 25 toward the polarization beam splitter 24. Of the backscattered light, the circularly polarized light component corresponding to the specular reflection component passes through the wave plate 26 such as ¼ again to become the P-polarized beam 104, passes through the polarizing beam splitter 24 with low loss, and passes through the beam. It goes to the splitter (branch optical system) 27. Most of the P-polarized beam 104 passes through a beam splitter (branch optical system) 27 and is condensed by the imaging lens 31a onto the incident surface of the optical fiber 33a for detecting foreign matter scattered light.
[0040]
As shown in FIG. 2, the center position 73b of the wafer W and the incident surface of the detection optical fiber 33a are in an imaging relationship, but the (light receiving area) of the incident end surface is the defocused wafer ends 73a and 73c. The scattered light from the light is also detectable. Accordingly, foreign matter backscattered light from the front to the back of the wafer can be detected with substantially the same sensitivity by the detection optical fiber 33a. In order to secure a large light receiving surface, a method using a bundle fiber or a liquid light guide is effective. The scattered light generated on the processing chamber inner wall 5 forms an image in front of the light receiving surface of the foreign matter scattered light detection optical fiber 33a (the position of the spatial filter 36). Therefore, the scattered light is processed by installing the spatial filter 36 at the imaging position. The scattered light generated on the inner wall 5 of the chamber is shielded. The emission end of the optical fiber 33a for detecting foreign matter scattered light is connected to a spectroscope 34a such as a monochromator or an interference filter set to the wavelength of the laser light source 12, and the wavelength component of the foreign matter scattered light from the plasma emission by the spectroscope 34a. After wavelength separation alone, it is photoelectrically converted by a photoelectric conversion element 35a such as a photodiode or a photomultiplier tube. The photoelectrically converted detection signal is amplified by the amplifier 50a, and the lock-in amplifier 51a uses the rectangular wave signal having a frequency of 170 kHz and a duty of 50% output from the oscillator 13 used for intensity modulation of the laser light as a reference signal. Synchronous detection is performed, and a foreign matter scattered light component having a frequency of 170 kHz is extracted from the detection signal.
[0041]
As shown in FIG. 3, the inventors of the present application have verified through experiments that the intensity of plasma emission is synchronized with the modulation frequency of the high frequency power for plasma excitation. As shown in FIG. 4, a foreign substance signal obtained by performing wavelength separation from the light emission of the plasma generated by the high-frequency power by the spectroscope 34, and performing modulation and synchronous detection at the frequency 170 kHz, which is different from the plasma excitation frequency and its integral multiple, From the plasma emission, it is separated and detected in two regions of wavelength and frequency. The inventors of the present application have experimentally confirmed that this method can detect weak foreign matter scattered light from plasma emission with high sensitivity. That is, as shown in FIG. 4, the plasma emission is continuously distributed in the wavelength region, but discretely exists in the frequency region, and there is an empty region in the frequency region. Therefore, for example, a laser beam having a wavelength of 532 nm is incident on the plasma processing chamber 86 after being intensity-modulated at a frequency of 170 kHz, for example, different from the frequency of the plasma emission. If only the peak signal is extracted, the scattered light from the foreign matter can be separated from the plasma emission and detected.
[0042]
In this way, by installing the spatial filter 36 at the imaging position in front of the light receiving surface of the foreign matter scattered light detection optical fiber 33a, the scattered light generated on the processing chamber inner wall 5 is shielded and the floating foreign matter on the wafer W is blocked. It becomes possible to make the scattered light incident on the optical fiber 33a for detecting foreign matter scattered light incident. Furthermore, by making the wavelength and intensity modulation frequency of the laser light incident on the plasma processing chamber 86 different from the wavelength and frequency of the plasma emission, it is possible to detect the scattered light from the suspended foreign matter separately from the plasma emission. It becomes.
[0043]
The output of the lock-in amplifier 51a is sent to the computer 42. In the computer 42, a scanning signal is sent to the galvano mirror 25 via the galvano driver 29, and the foreign substance signal captured at each scanning position while scanning the beam is displayed on the display 41 one by one in the form shown in FIG. 5, for example. To do. As shown in FIG. 6, the computer 42 takes the difference between the output at the n-th scanning and the output at the (n−1) -th scanning at each detection position, and displays only a change greater than a certain value on the display 41. When it is displayed, it becomes easy to determine the foreign substance signal. In this display example, a measurement result with five lines of irradiation light on a φ200 mm wafer is shown. When scattered light is generated by floating foreign substances in the plasma, large signals 81a, 81b, 81c, 81d, and 81e on the pulse appear as shown at five points in FIG. The computer 42 compares the signal intensity with respect to the particle diameter obtained by experiments in advance and the detected foreign substance signal intensity to determine the size of the foreign substance, the number of foreign substances from the number of the pulse-like signals, and the signal. The occurrence position of the foreign matter is determined from the scanning position when the is detected. Further, the computer 61 determines the contamination state in the processing chamber from the determined number and size of the foreign matter, and terminates the etching process when the total number of foreign matter generation exceeds a preset reference value. Can output information such as informing the operator of the plasma processing apparatus.
[0044]
Next, a method of detecting the processing chamber inner wall scattered light will be described. The circular or elliptically polarized beam 103 guided into the plasma processing chamber 86 strikes the inner wall 5 of the plasma processing chamber 86. At this time, the state of reflection and scattering varies depending on the state of the surface of the inner wall 5 of the plasma processing chamber 86. FIG. 7 shows a case where the surface state of the inner wall 5 of the plasma processing chamber 86 is a flat state with few irregularities. When the surface state of the plasma processing chamber inner wall 5 is a flat state with little unevenness (a state in which reaction products are not attached and plasma damage is less contaminated immediately after cleaning or cleaning), the inner wall of the plasma processing chamber 86 Most of the circular or elliptically polarized beam 103 hitting 5 is reflected. Therefore, when the beam is scanned in a plane parallel to the wafer surface by rotating the galvanometer mirror 25, most of the reflected light on the inner wall 5 of the plasma processing chamber 86 is observed when the beam scanning position is at the wafer center. The light passes through the work window 10 and is reflected by the galvanometer mirror 25 and travels toward the polarization beam splitter 24. Since most of the reflected light (scattered light) on the inner wall 5 of the plasma processing chamber 86 is a circularly polarized light component corresponding to a regular reflection component, the P polarized light beam 105 passes through the wave plate 26 such as ¼ again. Thus, the light passes through the polarization beam splitter 24 with low loss and travels toward the beam splitter (branch optical system) 27. A part of the P-polarized beam 105 is reflected by the beam splitter 27 and condensed by the imaging lens 31b on the incident surface (position of the pinhole 39) of the processing chamber reflected light detecting optical fiber 33b. Since a pinhole (aperture) 39 is provided at a position substantially in an imaging relationship with the inner wall 5 of the plasma processing chamber 86 by the lens 31b in front of the processing chamber reflected light detecting optical fiber 33b, the pinhole is provided. 39 passes only the reflected light (scattered light) from the inner wall 5 of the plasma processing chamber 86 and a part of the plasma emission with a high emission intensity. As a result, the processing chamber reflected light detection optical fiber 33b detects only the reflected light (scattered light) from the inner wall 5 of the plasma processing chamber 86 and a part of the plasma emission with a high emission intensity. As described above, since a part of the plasma light emission having a high light emission intensity is incident on the processing chamber reflected light detection optical fiber 33b, it is necessary to erase a signal generated by a part of the plasma light emission as described below. There is.
[0045]
That is, since the exit end of the processing chamber reflected light detection optical fiber 33b is connected to a spectrometer 34b such as a monochromator or an interference filter set to the wavelength of the laser light source 12, the spectrometer 34b emits light from the plasma emission. After only the wavelength component of the reflected light from the inner wall 5 is wavelength-separated, it is photoelectrically converted by a photoelectric conversion element 35b such as a photodiode or a photomultiplier tube. The photoelectrically converted detection signal is amplified by an amplifier 50b, and then a rectangular wave signal having a frequency of 170 kHz and a duty of 50% output from the oscillator 13 used for the intensity modulation of the laser beam by the lock-in amplifier 51b is used as a reference signal. Synchronous detection is performed, and a reflected light (scattered light) component from the inner wall 5 having a frequency of 170 kHz is extracted from the detection signal. The output of the lock-in amplifier 51b is sent to the computer 42. In the computer 42, a scanning signal is sent to the galvano mirror 25 via the galvano driver 29, and a signal indicating the contamination state of the inner wall 5 captured at each scanning position while scanning the beam is, for example, as shown in FIG. It displays on the display 41 one by one. Here, when the beam scanning position deviates from the center of the wafer, the propagation optical axis of the reflected light from the inner wall 5 of the plasma processing chamber 86 is shifted from the irradiation beam optical axis, so that it is almost incident on the scattered light detection optical system 2001. Will not.
[0046]
As described above, the surface state of the inner wall 5 of the plasma processing chamber 86 is a flat state with little unevenness (a state in which the reaction product is not attached to the reaction product immediately after being cleaned or cleaned, and is not contaminated with little plasma damage). As shown in FIG. 9, the shape of the detection signal obtained by one beam scanning is such that the signal intensity is large at the wafer center and the signal intensity is small at the wafer edge.
[0047]
On the other hand, as the plasma processing is advanced, reaction products adhere to the inner wall 5 of the plasma processing chamber 86 or are damaged due to plasma damage and the surface of the inner wall 5 is uneven. Will do. FIG. 8 shows a case where the inner wall 5 of the plasma processing chamber 86 is contaminated and the surface is uneven. Thus, when the inner wall 5 is contaminated and irregularities are generated, most of the circular or elliptically polarized beam 103 hitting the inner wall 5 is scattered. Accordingly, when the galvano mirror 25 is rotated and the beam 103 is scanned in a plane parallel to the wafer surface, the specular reflection component is increased as irregularities increase on the surface of the inner wall 5 of the plasma processing chamber 86 (contamination progresses). As a result, the difference in the signal intensity depending on the beam scanning position gradually decreases as shown in FIGS. 9, 10, 11, and 12. Therefore, the thickness of the accumulated reaction product indicating the contamination state of the inner wall 5 of the plasma processing chamber 86 and the change in the profile of the reflected (scattered) light signal in accordance with the detection position extracted from the lock-in amplifier 51b. If the relationship is examined and input to the storage device 40 and stored, the computer 42 can monitor the contamination status of the inner wall 5 of the plasma processing chamber 86.
By the way, since the inner wall 5 of the plasma processing chamber 86 has a generally cylindrical shape, when it is not contaminated as shown in FIG. The propagation optical axis of the reflected light deviates from the irradiation beam optical axis and hardly enters the scattered light detection optical system 2001.
[0048]
On the other hand, when the contamination progresses as shown in FIG. 8, when the beam 103 is irradiated while being shifted from the center of the wafer, more scattered light is generated from the inner wall 5, and the scattered light detection optical system 2001 is irradiated. Incident light is detected.
Therefore, if the rotation angle of the galvanometer mirror 25 is detected and the deviation amount (detection position) of the beam 103 from the wafer center is set, the accumulated reaction product indicating the contamination state of the inner wall 5 at the set position in advance. If the relationship between the thickness of the signal and the change in intensity of the reflected (scattered) light signal at the set position extracted from the lock-in amplifier 51b is examined and input and stored in the storage device 40, the computer 42 The contamination status of the inner wall 5 of the processing chamber 86 can be monitored.
On the other hand, of the reflected light (scattered light) from the inner wall 5 of the plasma processing chamber 86, the transmitted light that passes through the beam splitter 27 is shielded by the spatial filter 36, and therefore enters the foreign matter scattered light detection fiber 33a. Will not.
[0049]
As described above, according to the first embodiment, by the modulation / synchronous detection method, the intensity change of the scattered light indicating the change of the unevenness that is the contamination state of the inner wall 5 in the two regions of wavelength and frequency. Can be detected separately from the plasma emission, and the contamination of the inner wall can be detected with high sensitivity. Based on the results, the adhering reaction can be achieved by taking measures such as washing or cleaning. It is possible to suppress the occurrence of floating foreign matters in the plasma caused by peeling of the product. Naturally, it is possible to detect the intensity change of the scattered light indicating the change of the unevenness which is the contamination state of the inner wall 5 separately from the floating foreign matter.
[0050]
In addition, according to the first embodiment, the above-described modulation / synchronous detection method separates weak foreign matter scattered light from plasma light emission, which is a problem in foreign matter detection in plasma, in two regions of wavelength and frequency. The detection sensitivity is greatly improved compared to the conventional wavelength separation only method, and the detection sensitivity of floating foreign substances in plasma is greatly improved. Although the limit of about φ1 μm is the limit, the method of the present embodiment can improve the minimum detection sensitivity to about φ0.2 μm, and can also stably detect foreign matter over the entire wafer surface. can get. Furthermore, since foreign matter detection is performed on the entire surface of the wafer to determine the number, size, and distribution of foreign matter, the operator can check the information on the display 41 in real time, for example.
[0051]
In addition, according to the first embodiment, since the state of contamination of the inner wall of the processing chamber can be monitored while plasma is emitted, measures such as cleaning and cleaning are taken early to prevent sudden large amounts of suspended foreign matter. It is possible to suppress the occurrence and improve the yield. In addition, according to the first embodiment, the state of contamination in the processing chamber is determined in real time based on information on the number, size, and distribution of detected floating foreign substances while plasma is emitted. Therefore, for example, the apparatus operating rate can be improved by optimizing the cleaning time, the occurrence of sudden masses can be detected early, and the yield can be improved.
[0052]
In addition, according to the first embodiment, since the processing can proceed while constantly monitoring the contamination status in the processing chamber, the semiconductor substrate and the liquid crystal substrate manufactured in this way include foreign matters exceeding the reference value. High quality and reliable products manufactured in no environment.
Further, according to the first embodiment, it is possible to reduce the frequency of determining the contamination status of the processing chamber using the dummy wafer and determining the contamination status by sampling inspection, so that the cost of the dummy wafer can be reduced.
[0053]
Next, a second embodiment according to the present invention will be described with reference to FIGS. FIG. 14 is a diagram showing a configuration of an etching processing apparatus having a plasma floating particle measuring apparatus with a processing chamber wall contamination status monitoring function according to the second embodiment.
[0054]
The apparatus for measuring suspended solids in a plasma with the function of monitoring the state of contamination in the processing chamber wall is mainly composed of a laser illumination optical system 2000, a scattered light detection optical system 2002, and a control / signal processing system 6001, and the laser illumination optical system 2000 and scattered light detection. The illumination light exit portion and the detection light entrance portion in the optical system 2002 are arranged so as to face the observation window 10 provided on the side surface of the plasma processing chamber 86.
[0055]
The second embodiment is different from the first embodiment in that the reflected (scattered) light from the inner wall 5 of the plasma processing chamber 86 is detected by the image sensor 33c such as a CCD camera, and the plasma processing chamber 86 is detected. The determination of the contamination status of the inner wall 5 is made from the image obtained by the image sensor 33c such as the CCD camera. That is, since the generated speckle pattern changes depending on the unevenness of the surface of the inner wall 5 of the plasma processing chamber 86, the speckle pattern is captured by the image sensor 33c as shown in FIG. A subtle change in the surface state of the inner wall 5 can be detected from the change in the speckle pattern detected based on the above. When reaction products adhere immediately after cleaning or cleaning, or when plasma damage occurs and contamination progresses, the surface state of the inner wall 5 changes from a flat state to an uneven state, and speckle. It will increase from the state where there is no pattern. Therefore, an image reflected from the surface of the inner wall 5 is picked up by the image pickup device 33c having a light receiving surface at the image forming position of the inner wall 5, and the picked-up image signal is processed by the computer 42 (for example, in a two-dimensional direction). By performing differential processing (Laplacian filtering processing), it is possible to detect the contamination state of the inner wall 5 as a change in speckle pattern (for example, a change in shading of the speckle pattern). However, the plasma emission light needs to be filtered (shielded) by a filter 45 such as a wavelength filter so as not to enter the imaging element 33c.
[0056]
As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained, and the surface state of the inner wall 5 of the plasma processing chamber can be left as an image. It becomes.
[0057]
In the first and second embodiments, a side scattered light detection optical system as disclosed in JP-A-11-251252 can be used in combination.
[0058]
As described above, the measurement result of the contamination state of the inner wall of the processing chamber and / or the measurement result of the foreign substance floating in or near the plasma may be a diagnostic unit (42 or other production line management apparatus). Control means for diagnosing and reducing the adhesion of reaction products to the inner wall of the processing chamber or the side wall of the electrode (for example, the means for controlling the temperature of the inner wall of the processing chamber or the electrode side wall or along the inner wall of the processing chamber) Thus, the feedback of the magnetic field generating means 37 (shown in FIGS. 1 and 14) and control of the control means 37 can reduce adhesion of reaction products in the processing chamber. In addition, the diagnosis unit may remove the substrate to be processed from the production line based on the diagnosis result, and may perform cleaning by issuing a cleaning instruction to stop the introduction of the substrate to be processed.
[0059]
In addition, according to the embodiment of the present invention, the minimum detection sensitivity of floating foreign matters in plasma can be improved to about φ0.2 μm, and stable foreign matter detection can be performed over the entire wafer surface. Based on the distribution information, it is possible to determine the contamination status in the processing chamber in real time and at the same time monitor the contamination status of the processing chamber wall. Can be detected early and the yield is improved. In addition, since the processing can proceed while constantly monitoring the contamination status in the processing chamber, the semiconductor substrate and the liquid crystal substrate manufactured in this way are manufactured in an environment that does not contain foreign substances exceeding the reference value, and are of high quality. It becomes a highly reliable product.
[0060]
Further, according to the present embodiment, it is possible to reduce the frequency of determination of contamination status of a processing chamber using a dummy wafer and contamination status determination by sampling inspection, so that the cost of the dummy wafer can be reduced.
[0061]
These effects enable real-time monitoring of the contamination status in the etching chamber, reduce the occurrence of defective wafers due to attached foreign matter, and enable the manufacture of high-quality semiconductor elements and the time for cleaning the equipment accurately. The effect of being able to grasp is born.
[0062]
In addition, since the frequency of the foreign object prior work check operation using the dummy wafer can be reduced, the effects of cost reduction and productivity improvement are produced. In addition, the production line can be automated.
[0063]
Next, a third embodiment of the present invention will be described based on FIG. 16, FIG. 17, and FIG. First, the concept of a method for manufacturing a semiconductor integrated circuit according to the present invention will be described with reference to FIGS.
[0064]
Step 100a is a film forming step for forming a film 601 to be processed such as a silicon oxide film on the wafer W, and step 100b is a film thickness measuring step for inspecting the thickness of the formed film. Step 100c is a resist application step for applying a resist 602 to the wafer W, and step 100d is a pattern transfer step for transferring the mask pattern 603 onto the wafer. Step 100e is a development step for removing the resist in the processed portion. Step 100f uses the resist pattern 604 as a mask to etch the processed film 601 in the resist removing portion 605 to form a wiring groove and a contact hole 606. Etching process. Step 100h is an ashing step for removing the resist pattern 604, and step 100i is a cleaning step for cleaning the front surface and the back surface of the wafer. The above series of steps is applied to, for example, formation of a contact hole.
[0065]
Next, the defect which arises when the foreign material which generate | occur | produced during the etching adheres to a wafer is demonstrated using FIG. FIG. 18 is a diagram illustrating an example of defects generated in contact hole etching, for example.
A foreign substance 701 indicates a foreign substance attached to the contact hole opening during etching. In this case, since the etching reaction is stopped by the adhered foreign matter, the contact hole at the foreign matter adhered portion is not opened, which becomes a fatal defect.
A foreign substance 702 indicates a foreign substance adhering to the inside of the contact hole during etching. Also in this case, since the etching reaction is stopped by the adhered foreign matter, the contact hole at the foreign matter adhered portion is not opened, resulting in a fatal defect.
[0066]
A foreign matter 703 and a foreign matter 704 indicate foreign matters that have adhered to the inside of the contact hole after etching. A foreign substance adhering to a portion having a high aspect ratio such as a contact hole is often difficult to remove even by cleaning. If the size of the foreign substance is large, such as a foreign substance 703, a contact failure occurs, which is fatal. It becomes a defect.
A foreign matter 705 indicates foreign matter attached to the resist pattern 604 during etching. In this case, the attached foreign matter 705 does not affect the etching reaction at all, and no fatal defect occurs due to the attached foreign matter 705.
In this way, even if foreign matter adheres, if the size of the foreign matter is not large enough to cause a defect, or if the attachment location is a non-etched area, it does not become a fatal defect and the foreign matter adheres to the wafer. But not all of them cause fatal defects. In addition, while the foreign matter 701 and the foreign matter 705 are foreign matters that are relatively easy to remove by cleaning, foreign matters that fall into the high-aspect ratio contact hole, such as the foreign matter 602, the foreign matter 703, and the foreign matter 704, are removed by washing. Is difficult.
[0067]
In the present invention, in the etching process 100f, the foreign substance generated in the processing chamber during the etching is detected in real time by the plasma floating foreign substance measuring apparatus 1100, and the processed wafer is transferred to the next process based on the foreign substance detection result. It is selected whether the remaining wafers are processed sequentially, whether the appearance inspection is performed before being sent to the next process, or the processing is stopped and the processing chamber is cleaned (maintenance).
[0068]
Here, the process to be performed next is selected by comparing the size and number of detected foreign substances with a preset standard value (foreign substance management standard).
Therefore, an example of a method for calculating the standard value (foreign matter management standard) in the present embodiment will be described next. As already explained, even if foreign matter adheres to the wafer, not all of them cause fatal defects. The probability that a fatal defect occurs due to the adhered foreign matter can be obtained by calculation from the relationship between the opening ratio and pattern density of the etching pattern, the wiring width, and the size and number of foreign matter that adhere. Therefore, the correlation between the size and number of foreign matter detected during the etching process and the size and number of foreign matter attached to the wafer is obtained in advance through experiments, and the probability that fatal defects are caused by the foreign matter detected during etching. Can be requested.
[0069]
The standard value (foreign matter management standard) is set based on the value obtained by the above means. In the following, an example of setting a standard value in the present embodiment is shown.
The standard value 1 is set so that the probability that a fatal defect will occur is very low (for example, about 1% or less of the fatal defect occurrence probability) if the number of detected foreign objects of a certain size or more is less than the specified value 1. To do. For example, the standard value 1 is 10 particles having a particle size of 0.4 μm or more.
The standard value 2 is a value at which the occurrence of a fatal defect is a concern (for example, the probability of the fatal defect occurrence) if the number of detected foreign objects of a certain size or more is less than the specified value 2 above the standard value 1 5% or less). For example, the standard value 2 is 30 particles having a particle size of 0.4 μm or more.
If the number of detected foreign objects having a certain size or more is the specified value 2 or more, many fatal defects occur (for example, a fatal defect occurrence probability of about 5% or more).
Based on the standard value, if the number of foreign particles detected during the etching process is less than the specified value 1, the probability of a fatal defect is low, so that the next wafer is processed. Do.
[0070]
If the number of foreign substances detected during the etching process is greater than or equal to the specified value 1 but less than the specified value 2, an appearance inspection is performed after the etching process is completed. If no fatal defect is confirmed as a result of the visual inspection, the wafer is sent to the next ashing step 1007. If a fatal defect is confirmed as a result of the visual inspection, it is determined whether the fatal defect is a remedyable defect. If it is determined that the defect can be repaired (eg, using a repair circuit) based on the determination result, the wafer is sent to the next ashing step 100h. If it is determined that the defect cannot be repaired based on the determination result, the defect is recorded, and then the wafer is sent to the next ashing step 100h. Thereafter, for example, when each chip is cut out by dicing, the chip including the irreparable defect is eliminated.
[0071]
In the case where the number of foreign substances detected during the etching process is larger than the specified value 2, the possibility of a large number of fatal defects occurring in the wafer to be processed thereafter is high. An operator of the etching apparatus is displayed on a monitor screen or notified by an alarm so that the etching process is interrupted and the plasma processing chamber is cleaned (maintenance).
[0072]
In an etching processing apparatus that does not include a plasma floating particle measuring apparatus, the processing chamber is not necessarily cleaned in an appropriate time. Therefore, cleaning is performed at a time when it is not necessary to clean, and the operation rate of the apparatus is reduced, or conversely, processing is continued even when the time to be cleaned has passed, resulting in a large amount of defective products and yield. It may be reduced.
There is also a method of performing a prior work with a dummy wafer for checking foreign matter in the processing chamber and determining the cleaning time from the result. In this case, extra work is performed during a series of steps, resulting in a decrease in throughput and a cost for dummy wafers. However, with the increase in wafer diameter, the cost of dummy wafers is inevitably increased, and the reduction of prior work using dummy wafers for checking foreign substances in the processing chamber is also a big problem.
[0073]
On the other hand, according to the present embodiment, since the object to be processed can be processed while monitoring the contamination status in the processing chamber in real time, the cleaning time is optimized, and no prior work with a dummy wafer is required. As a result, the cost of the dummy wafer can be reduced. In addition, the product manufactured by the process of the present embodiment can manufacture a high-quality product that does not include foreign substances exceeding a specified value, and thus a highly reliable product.
[0074]
In the above embodiment, an example of application to an etching processing apparatus has been described. However, as described above, the scope of application of the present invention is not limited to this example. By applying to an ashing apparatus or a film forming apparatus, real-time monitoring of foreign substances in the ashing apparatus and the film forming apparatus becomes possible, thereby reducing defects caused by the ashing process and the film forming process in the photolithography process. Therefore, it is possible to prevent the occurrence of defective products and improve the yield.
[0075]
【The invention's effect】
According to the present invention, it is possible to monitor the contamination state of the plasma processing chamber inner wall, so that countermeasures are taken in advance to prevent a large amount of foreign matter from being generated, thereby improving the yield and improving the quality. In addition, it is possible to obtain the effect of accurately grasping the apparatus cleaning time.
In addition, according to the present invention, it is possible to simplify the configuration and to monitor the contamination status of the plasma processing chamber inner wall and monitor the floating foreign matters in the plasma.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an etching processing apparatus having a plasma floating particle measuring apparatus with a function of monitoring a state of contamination in a processing chamber wall according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a simplified optical system for detecting foreign matter scattered light and processing chamber inner wall reflected (scattered) light in the first embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a state where a plasma excitation frequency and plasma emission are synchronized.
FIG. 4 is an explanatory diagram showing a state of wavelength / frequency separation from plasma emission of foreign matter scattered light.
FIG. 5 is a diagram showing temporal changes in detected light intensity at five points on the wafer in the first embodiment of the present invention.
FIG. 6 is a diagram showing a temporal change in the foreign substance signal intensity at five points on the wafer in the first embodiment of the present invention.
FIG. 7 is a diagram illustrating a state of reflection of irradiation laser light on a processing chamber wall according to the first embodiment of the present invention.
FIG. 8 is a diagram showing a state of scattering of irradiation laser light on a processing chamber wall in the first embodiment of the present invention.
FIG. 9 is a diagram showing a profile of reflected (scattered) optical signal intensity in a processing chamber wall in the first embodiment of the present invention.
FIG. 10 is a diagram showing a profile of reflected (scattered) optical signal intensity in the processing chamber wall in the first exemplary embodiment of the present invention.
FIG. 11 is a diagram showing a profile of reflected (scattered) optical signal intensity in the processing chamber inner wall according to the first embodiment of the present invention.
FIG. 12 is a diagram showing a profile of reflected (scattered) optical signal intensity in the processing chamber wall in the first exemplary embodiment of the present invention.
FIG. 13 is a diagram showing a change over time of the profile of the reflected (scattered) optical signal intensity in the processing chamber inner wall according to the first embodiment of the present invention.
FIG. 14 is a diagram showing a configuration of an etching processing apparatus having a plasma floating foreign substance measuring apparatus with a function of monitoring the contamination of a processing chamber wall according to a second embodiment of the present invention.
FIG. 15 is a view showing a processing room inner wall reflected (scattered) light image according to the second embodiment of the present invention;
FIG. 16 schematically shows a manufacturing process of a semiconductor integrated circuit device, in which an etching processing apparatus with a floating particle measuring apparatus in plasma according to a third embodiment of the present invention is introduced, along the flow of processing. It is explanatory drawing.
FIG. 17 is an explanatory view schematically showing a contact hole formation process according to the third embodiment of the present invention along the flow of processing using a cross-sectional structure;
FIG. 18 is an explanatory view schematically showing an example of a defect caused by attached foreign matter in a contact hole etching step according to a third embodiment of the present invention.
[Explanation of symbols]
5 ... inner wall, 10 ... observation window, 12 ... laser light source, 13 ... oscillator, 14 ... AO modulator, 18 ... focusing lens, 24 ... polarization beam splitter, 26 ... wave plate such as 1/4, 27 ... beam splitter (Branching optical system) 29 ... Galvano driver, 31a, 32b ... Imaging lens, 33a ... Optical fiber for detecting foreign matter scattered light, 33b ... Optical fiber for detecting reflected light in processing chamber, 33c ... Imaging device (CCD camera), 34a 34b ... Spectroscope, 35a, 35b ... Photoelectric conversion element, 36 ... Spatial filter, 39 ... Aperture (pinhole), 40 ... Storage device, 41 ... Display, 42 ... Computer, 45 ... Filter, 50a, 50b ... Amplifier, 51a, 51b ... lock-in amplifier, 83 ... signal generator, 84 ... power amplifier, 85 ... distributor, 86 ... plasma processing chamber, 8 ... Upper electrode, 82 ... Lower electrode, 71 ... Plasma, W ... Semiconductor substrate (substrate to be processed), 100a ... Film forming process, 100b ... Film thickness measuring process, 100c ... Resist coating process, 100d ... Pattern transfer process, 100e ... Development step, 100f ... etching step, 100g ... foreign matter determination unit, 100h ... ashing step, 100i ... cleaning step, 2000 ... laser illumination optical system, 2001 ... scattered light detection optical system, 6000 ... control / signal processing system.

Claims

Processing to generate plasma chamber, in the manufacturing method of a semiconductor device for manufacturing a semiconductor device by processing the semiconductor substrate by plasma obtained by said occurrence,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength and intensity-modulated at a desired frequency through an observation window in a plane parallel to the semiconductor substrate surface in the processing chamber;
At each scanning position of the laser beam irradiated by scanning in the irradiation step, the first reflected light from the inner wall of the processing chamber obtained from the inside of the processing chamber through the observation window is transmitted by the first imaging optical system. The first reflected light that has been imaged is passed through a stop provided at a position that is substantially in an imaging relationship with the inner wall by the first imaging optical system, and the first reflected light that has passed therethrough Is separated by the desired wavelength, received by a first detector and converted into a first received light signal, and the intensity modulated frequency component is extracted from the converted first received light signal. An inner wall detecting step of detecting a first signal indicating a change in a difference in signal intensity at each scanning position according to a change in the uneven state of the inner wall separately from the one due to plasma emission; and
Plasma processing for the semiconductor substrate based on the contamination state of the inner wall of the processing chamber calculated based on a change in signal intensity difference according to each scanning position of the first signal detected in the inner wall detecting step And a control step for controlling the semiconductor device .

Processing to generate plasma chamber, in the manufacturing method of a semiconductor device for manufacturing a semiconductor device by processing the semiconductor substrate by plasma obtained by said occurrence,
An irradiation step of irradiating the processing chamber with a laser beam having a desired wavelength and intensity-modulated at a desired frequency through an observation window;
A branching step of branching reflected light obtained from the inside of the processing chamber through the observation window by a branching optical system at each scanning position of the laser beam scanned and irradiated by the irradiation step;
At each scanning position of the laser beam obtained by branching in the branching step, the first reflected light from the inner wall of the processing chamber is imaged by the first imaging optical system, and the imaged first The reflected light is passed through a stop provided at a position that is substantially in an imaging relationship with the inner wall by the first imaging optical system, and the first reflected light that has passed is wavelength-separated at the desired wavelength. Each of the scans is received according to a change in the uneven state of the inner wall by extracting the intensity modulated frequency component from the converted first received light signal. An inner wall detecting step for detecting a first signal indicating a change in a difference in signal intensity at a position separately from that due to plasma emission;
At each scanning position of the laser beam obtained by branching in the branching step, second reflected light by backscattered light generated from foreign matter floating in or near the plasma is connected by a second imaging optical system. The reflected light generated from the inner wall of the formed second reflected light is shielded by a spatial filter, and the second reflected light that has passed through the spatial filter is wavelength-separated by the desired wavelength to obtain a first 2 is received and converted into a second received light signal, and the intensity-modulated frequency component is extracted from the converted second received light signal, whereby the second signal indicating the foreign matter is plasma-emitted. A foreign object detection step for detecting separately from the
The contamination state of the inner wall of the processing chamber calculated based on the change in the signal intensity difference corresponding to each scanning position of the first signal detected in the inner wall detection step and detected in the foreign matter detection step the method of manufacturing a semiconductor device characterized by a control step of controlling a plasma process on the semiconductor substrate on the basis of the occurrence of foreign matter floating in the plasma or in an area in proximity thereof are calculated based on the second signal .

Processing to generate plasma chamber, in the manufacturing method of a semiconductor device for manufacturing a semiconductor device by processing the semiconductor substrate by plasma obtained by said occurrence,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength through the observation window in a plane parallel to the surface of the substrate to be processed in the processing chamber;
At each scanning position of the laser beam irradiated by the irradiation step, the plasma emission obtained through the observation window is shielded by a filter, and a speckle pattern generated due to the uneven state of the surface of the inner wall of the processing chamber is formed. An inner wall detection step of forming an image with an image optical system, capturing the imaged speckle pattern image with an image sensor and detecting it as an image signal;
A control step for controlling plasma processing on the semiconductor substrate based on a contamination state of the inner wall of the processing chamber calculated based on a change in speckle pattern detected based on the image signal detected in the inner wall detecting step. A method for manufacturing a semiconductor device , comprising:

Processing to generate plasma chamber, in the manufacturing method of a semiconductor device for manufacturing a semiconductor device by processing the semiconductor substrate by plasma obtained by said occurrence,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength and intensity-modulated at a desired frequency through an observation window in a plane parallel to the semiconductor substrate surface in the processing chamber;
A branching step of branching reflected light obtained from the inside of the processing chamber through the observation window by a branching optical system at each scanning position of the laser beam scanned and irradiated by the irradiation step;
At each scanning position of the laser beam obtained by branching in the branching step, the plasma emission obtained through the observation window is shielded by a filter, and a speckle pattern generated by the uneven state of the inner wall surface of the processing chamber is formed. An inner wall detection step of forming an image with an image optical system, capturing the imaged speckle pattern image with an image sensor and detecting it as an image signal;
At each scanning position of the laser beam obtained by branching in the branching step, second reflected light by backscattered light generated from foreign matter floating in or near the plasma is connected by a second imaging optical system. The reflected light generated from the inner wall of the formed second reflected light is shielded by a spatial filter, and the second reflected light that has passed through the spatial filter is wavelength-separated by the desired wavelength to obtain a first 2 is received and converted into a second received light signal, and the intensity-modulated frequency component is extracted from the converted second received light signal, whereby the second signal indicating the foreign matter is plasma-emitted. A foreign object detection step for detecting separately from the
The contamination status of the inner wall of the processing chamber calculated based on the change in the speckle pattern detected based on the image signal detected in the inner wall detection step and the second signal detected in the foreign matter detection step the method of manufacturing a semiconductor device characterized by a control step of controlling a plasma process on the semiconductor substrate in the plasma is calculated based on or based on the occurrence of foreign matter floating in the vicinity thereof.

In a plasma processing method of generating plasma in a processing chamber and processing a target substrate with the generated plasma,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength and intensity-modulated at a desired frequency through an observation window in a plane parallel to the surface of the substrate to be processed;
At each scanning position of the laser beam irradiated by scanning in the irradiation step, the first reflected light from the inner wall of the processing chamber obtained from the inside of the processing chamber through the observation window is transmitted by the first imaging optical system. The first reflected light that has been imaged is passed through a stop provided at a position that is substantially in an imaging relationship with the inner wall by the first imaging optical system, and the first reflected light that has passed therethrough Is separated by the desired wavelength, received by a first detector and converted into a first received light signal, and the intensity modulated frequency component is extracted from the converted first received light signal. An inner wall detecting step of detecting a first signal indicating a change in a difference in signal intensity at each scanning position according to a change in the uneven state of the inner wall separately from the one due to plasma emission; and
A determination step of determining a contamination state of the inner wall of the processing chamber based on a change in difference in signal intensity according to each scanning position of the first signal detected in the inner wall detection step. A plasma processing method.

In a plasma processing method of generating plasma in a processing chamber and processing a target substrate with the generated plasma,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength and intensity-modulated at a desired frequency through an observation window in a plane parallel to the surface of the substrate to be processed;
A branching step of branching reflected light obtained from the inside of the processing chamber through the observation window by a branching optical system at each scanning position of the laser beam scanned and irradiated by the irradiation step;
At each scanning position of the laser beam obtained by branching in the branching step, the first reflected light from the inner wall of the processing chamber is imaged by the first imaging optical system, and the imaged first The reflected light is passed through a stop provided at a position that is substantially in an imaging relationship with the inner wall by the first imaging optical system, and the first reflected light that has passed is wavelength-separated at the desired wavelength. Each of the scans is received according to a change in the uneven state of the inner wall by extracting the intensity modulated frequency component from the converted first received light signal. An inner wall detecting step for detecting a first signal indicating a change in a difference in signal intensity at a position separately from that due to plasma emission;
At each scanning position of the laser beam obtained by branching in the branching step, second reflected light by backscattered light generated from foreign matter floating in or near the plasma is connected by a second imaging optical system. The reflected light generated from the inner wall of the formed second reflected light is shielded by a spatial filter, and the second reflected light that has passed through the spatial filter is wavelength-separated by the desired wavelength to obtain a first 2 is received and converted into a second received light signal, and the intensity-modulated frequency component is extracted from the converted second received light signal, whereby the second signal indicating the foreign matter is plasma-emitted. A foreign object detection step for detecting separately from the
The contamination state of the inner wall of the processing chamber is determined based on the change in the difference in signal intensity corresponding to each scanning position of the first signal detected in the inner wall detection step, and is detected in the foreign matter detection step. And a determination step of determining a generation state of a foreign substance floating in or near the plasma based on the second signal.

In a plasma processing method of generating plasma in a processing chamber and processing a target substrate with the generated plasma,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength through the observation window in a plane parallel to the surface of the substrate to be processed in the processing chamber;
At each scanning position of the laser beam irradiated by the irradiation step, the plasma emission obtained through the observation window is shielded by a filter, and a speckle pattern generated due to the uneven state of the surface of the inner wall of the processing chamber is formed. An inner wall detection step of forming an image with an image optical system, capturing the imaged speckle pattern image with an image sensor and detecting it as an image signal;
And a determination step of determining a contamination state of the inner wall of the processing chamber based on a change in a speckle pattern detected based on the image signal detected in the inner wall detection step.

In a plasma processing method of generating plasma in a processing chamber and processing a target substrate with the generated plasma,
An irradiation step of scanning and irradiating a laser beam having a desired wavelength and intensity-modulated at a desired frequency through an observation window in a plane parallel to the surface of the substrate to be processed;
A branching step of branching a reflected light image obtained from the inside of the processing chamber through the observation window by a branching optical system at each scanning position of the laser beam irradiated by scanning in the irradiation step;
At each scanning position of the laser beam obtained by branching in the branching step, the plasma emission obtained through the observation window is shielded by a filter, and a speckle pattern generated by the uneven state of the inner wall surface of the processing chamber is formed. An inner wall detection step of forming an image with an image optical system, capturing the imaged speckle pattern image with an image sensor and detecting it as an image signal;
At each scanning position of the laser beam obtained by branching in the branching step, second reflected light by backscattered light generated from foreign matter floating in or near the plasma is connected by a second imaging optical system. The reflected light generated from the inner wall of the formed second reflected light is shielded by a spatial filter, and the second reflected light that has passed through the spatial filter is wavelength-separated by the desired wavelength to obtain a first 2 is received and converted into a second received light signal, and the intensity-modulated frequency component is extracted from the converted second received light signal, whereby the second signal indicating the foreign matter is plasma-emitted. A foreign object detection step for detecting separately from the
Based on the change in the speckle pattern detected based on the image signal detected in the inner wall detection step, the contamination status of the inner wall of the processing chamber is determined, and the second signal detected in the foreign matter detection step is determined. And a determination step of determining a generation state of a foreign substance floating in or near the plasma based on the plasma processing method.