【０００１】
【発明の属する技術分野】
本発明は、半導体製造装置等に用いられる高品質な光学材料を研磨する研磨装置において、装置稼動中の研磨状態（研磨進行状況）を高精度で安定的に計測、監視およびプロセス評価し、研磨界面に於ける研磨液のながれ、研磨材との摩擦などで発生する温度分布等の計測および制御を的確に行なうことのできる研磨可視化検出方法、研磨液ながれ、温度分布測定方法および研磨装置に関するものである。
【０００２】
【従来の技術】
近年、半導体プロセスの高集積化に伴ない、露光装置等に使用する光学材料の品質向上が要求され、レンズ等の製作に用いる研磨装置の性能もより一層高品質なものが要求されている。
【０００３】
従来、研磨加工プロセスは、研磨液、研磨剤を介在させた状態で研磨工具（研磨パッド）により加工される。被研磨材の加工面（研磨面）は研磨工具と接触しているため、研磨加工中に研磨進行状態を可視化観察、計測、評価することは容易ではない。
【０００４】
また、研磨液中の特殊な状況での研磨加工については、現象的にはまだ充分に分析解明がされていない部分がある一方、加工中の研磨面に於ける諸パラメーターの状態が研磨特性に大きく影響する事が知られている。
【０００５】
ここでは研磨プロセス評価要因の１つであると考えられる加工界面への直接的な作用を知る為に研磨液ながれの可視化測定と共に研磨材との摩擦などで発生する温度と研磨工具固定化の進行状態、砥粒分散等種々の加工要因パラメータを測定、観察モニタリングする方法や研磨パッド面状中心部から研磨部材に研磨液を正しく横切る方向に供給する細長いガイドを設け、研磨加工能率安定化を実現させる。
【０００６】
一般に、流体速度を計測する場合、ＬＤＶ法（ＬａｓｅｒＤｏｐｐｌｅｒＶｅｌｏｃｉｍｅｔｅｒ流速計）が良く知られ、市販品もあり広く用いられている。
【０００７】
ＬＤＶ法は移動物体にレーザー光を照射し、該移動物体からの散乱光の周波数が移動物体の移動速度に比例してシフトする効果（ドップラー効果）を利用して移動速度を測定する方法であり、特開平５−１８９８２号公報例や表面血流測定装置（特開平５−１５５０１号公報）等、流速計測法として利用されている。
【０００８】
またレーザー励起蛍光法を用いたＰＩＶ法（Ｐａｒｔｉｃｌｅ Ｉｍａｇｅ Ｖｅｌｏｃｉｍｅｔｒｙ）も流体速度計測法として良く用いられている、ＰＩＶ法はトレーサ粒子が供給された流体にレーザなどの励起光源を照射し、流体粒子より発する散乱光をＣＣＤなどで受光し、画像処理して流体の速度を可視化計測する方法であり、特開平５−２９７０１４号公報例や特開平８−２１１０８７号公報例が物体のながれ計測方法として報告されている。
【０００９】
また研磨材との摩擦や工具の摩耗や損傷などで発生する温度上昇、温度測定法については一般的には赤外線カメラを用いた赤外線放射温度計などで研磨工具あるいは研磨材面内の温度分布を求める方法や、熱電対を使用した方法が一般に行われているが、（特開平７−９４４５２号公報例、特開平１１−１０４９５５号公報例）しかし微小な温度変化を精度良く測定することや、直接必要な場所の温度を計測する事は困難で研磨部近くの熱電対を接置した箇所の測定になり直接的な評価は出来ない、また充分な応答速度を得ることは難しい等の、問題が指摘されている。
【００１０】
【発明が解決しようとする課題】
ＬＤＶ法は２本のレーザーを入射交差させるため、観測点がレーザーの交差箇所１点でしか観測出来ない為、流速分布は計測出来ないという問題があった。
【００１１】
またこの方法は流体が透明な状態では可能だが、混濁した状態では検出ノイズＳＮＲが悪く計測出来ない事から、研磨液中研磨剤等混濁した状態では計測使用出来ない。
【００１２】
またレーザー励起蛍光法を用いたＰＩＶ法（Ｐａｒｔｉｃｌｅ Ｉｍａｇｅ Ｖｅｌｏｃｉｍｅｔｒｙ）も良く用いられるが検出トレーサーとして蛍光粒子を研磨液中に混入発光波長のみを検出してマクロ的な流れを計測する事は可能だが、発光感度が微少で微細な粒子検出や、研磨液中混在する実砥粒等の観察検出は研磨工具などの背景ノイズＳＮＲ等の問題で前記ＬＤＶ法同様観察計測は難しい。また可視化画像から温度情報を得るには、前記記載の一般的には赤外線カメラを用いた赤外線放射温度計などで研磨工具あるいは研磨材面内の温度分布を求める方法が行われているが、微小な温度変化を精度良く測定することや、直接的な評価が出来ないまた充分な応答速度を得ることは難しい等の問題が指摘されている。
【００１３】
本発明は上記従来の技術の有する未解決の課題に鑑みてなされたものであり、研磨の進行状態における前記種々情報を可視化計測、監視するとともに、研磨加工中の研磨プロセスの分析評価、研磨温度の測定調整等を高精度で行なうことのできる研磨可視化検出方法、及び研磨装置、研磨工具を提供することを目的とするものである。
【００１４】
【課題を解決するための手段】
前記目的を達成するため、本発明の研磨可視化検出方法は、研磨装置における研磨進行状況を検出するための研磨可視化検出方法であって、研磨プロセス情報をマクロ（巨視的）的に可視化計測する方法と研磨界面における微細砥粒の可視化観察の為のミクロ（微視的）な観察が可能とする為の以下手法を用いる。
【００１５】
研磨液の研磨摩擦界面への進入形態、ながれ観察には上記巨視的視野が必要でマクロ的な検出には従来の光学顕微拡大系を使用、２〜６ミクロン程度の蛍光粒子をトレーサとして使用、研磨工具等の背景光ノイズを除去する為に励起光源を照射、トレーサー粒子より発生する蛍光を観察逐次時系列的に像を画像処理装置に取り込む、得られた蛍光粒子画像をデジタル処理し、研磨面流れ場に注入された個々の蛍光粒子を解析する事によって研磨液ながれを可視化処理するものである。
【００１６】
しかし研磨液のような研磨剤、実砥粒などの非トレーサ粒子の混ざった混流分散体のながれでは前記光学顕微拡大系では微細蛍光粒子や実砥粒や研磨固定化進行状況における微細な砥粒等の可視化検出にはコントラストが小さく分解性能が得られず使用出来ない、そこで観察光学系には結晶構造を観察出来また屈折率の異なる組織の境界や凹凸変化を色や明暗のコントラストとして観察できる偏光顕微拡大系を採用、従来ＰＩＶ法を拡張し研磨加工面におけるマクロ的な評価と微細砥粒観察等微視的評価検出法を複合させ非トレーサ粒子可視化検出を実現する。また、温度計測には従来法赤外線放射温度計に変わる、マイクロカプセル化した感温粒子をトレーサに使用、ながれ測定と同様、発光ルミネッセンス強度より温度情報を得る、研磨面直接場におけるながれ観察と温度評価の同時計測が可能となり研磨プロセス現象分析が向上する。
【００１７】
【発明の実施の形態】
本発明の実施の形態を図面に基づいて説明する。
【００１８】
図１は実施の形態を示すもので、この研磨装置Ｍ１ は、研磨工具を構成する研磨パッド１を数Ｈｚで矢印Ｒで示す方向に直進揺動させる。ホルダー２に透明な光学材料（被研磨材）であるワークＷ１ が保持されており、その上面を研磨工具（パッド）１により研磨加工される。ホルダー２の下面は、ワークＷ１ に光を照射して研磨面が下から観察できるように、また研磨剤および蛍光トレーサ粒子を含んだ研磨液Ｌ１ が漏れないように、石英ガラス材で仕切られている。
【００１９】
研磨揺動軸３は、上部に蛍光粒子と研磨液の供給手段である蛍光トレーサー粒子供給および研磨液供給装置４が取り付けられ、そこから一定時間ごとに蛍光物質による蛍光粒子である蛍光トレーサー粒子が研磨液Ｌ１ に供給される。
【００２０】
この研磨装置Ｍ１ の下部には、研磨可視化検出装置Ｓ１ が配設され、その構成は以下の通りである。
【００２１】
蛍光トレーサー粒子に光（照明光）を照射する照明手段である照射部１０は、光源であるレーザー発振器１１と、研磨揺動軸３による研磨パッド１の揺動と同期をとって開閉されるシャッター手段である高速光ＡＯシャッター１２と、レーザー光口径を広げるためのコリメータ１３と、コリメータ１３を保持する鏡筒１４と、照射部１０全体の位置をコントロールするＸＹＺθステージである照射部ステージ１５で構成される。
【００２２】
可視化計測部２０は、前述の石英ガラス材からなる観測窓直下に取り付けられ、レーザー光の照射によって可視化された蛍光トレーサー粒子を観察することができるように粒子像を拡大するための拡大光学系２１を有する。拡大光学系２１は顕微鏡拡大系からマクロレンズ拡大系まで公知のものを任意に選択して取り付けることができ、また可視化像背景散乱ノイズ除去の為の波長フィルタが装填されており、研磨面全体の研磨プロセス情報をマクロ（巨視的）に取り込める事ができる。
【００２３】
拡大された可視化粒子像は、撮像手段であるＣＣＤカメラ２２によって、１０００×１０００画素の高解像な像として、画像読み込み装置とコンピュータを内蔵した画像処理装置２３に取り込まれる。また、照射部１０の高速光ＡＯシャッター１２と連動して、光エネルギーを与えた蛍光トレーサー粒子の蛍光のみを前記波長フィルタで選択しＣＣＤカメラ２２に取り込む、カメラに像を取込む為の同期制御手段である同期制御回路２４、および拡大光学系２１とＣＣＤカメラ２２の位置制御を行なうＸＹＺθステージである計測部ステージ２５が設けられる。
【００２４】
高速光ＡＯシャッター１２が開口すると、レーザー光は研磨パッド１とワークＷ１ の研磨界面に照射され、蛍光トレーサー粒子と研磨面より反射散乱光が発せられる。同期制御回路２４は、高速光ＡＯシャッター１２が閉じると同時に、すなわち遮光のタイミングに合わせて、ＣＣＤカメラ２２の画像読み込みを行なう画像処理装置２３にＣＣＤ電荷クリア信号を入力し、カメラ露光開始後蛍光トレーサー粒子の蛍光が観察されＣＣＤカメラ２２に画像として取り込むための信号を入力する。このようにして、研磨パッド１等からの散乱光によるノイズを除去し、蛍光トレーサー粒子からの蛍光のみを画像処理装置２３に読み込む。
【００２５】
このように蛍光トレーサー粒子からの時系列的に逐次蛍光粒子像のみを画像として取り込み、モニタ画面で研磨の進行状況をモニタし、画像データを画像処理して研磨液中のトレーサ粒子を追跡し研磨液ながれ像を可視化計測、観察する。
【００２６】
研磨開始直後では、被研磨材であるワークと研磨パッド間の粒子が凹凸にとどまり、その粒子密度分布はまだらになり、流速や流れ方向が複雑に変化する。しかし研磨が進行すると、研磨面が平坦化され粒子の密度分布は一様になる。同様に、粒子の流速および流れの方向も均一化される。
【００２７】
このように、蛍光粒子像の経時変化を画像処理することによってオンマシンで研磨進行状態を計測・監視することができる。また、コンピュータのメモリにあらかじめ記憶されている既知データによる研磨進行パターンと、取り込み画像の計測データによる画像処理パターンを逐次比較することで、研磨進行状態を計測、監視、評価することができる。
【００２８】
一方前に記載の研磨液のような研磨剤、実砥粒などの非トレーサ粒子の混ざった混流分散体のながれでは前記光学顕微拡大系では微細蛍光粒子や実砥粒等、また研磨固定化進行状況における微細な砥粒の挙動等の可視化検出にはコントラストが小さく分解性能が得られず前記通常の拡大手法では使用出来ない、そこで観察光学系には結晶構造を観察出来また屈折率の異なる組織の境界や凹凸変化を色や明暗のコントラストとして観察できる偏光顕微拡大系を採用、従来のＰＩＶ法を拡張し研磨加工面におけるマクロ的な評価と微細砥粒観察等微視的評価検出法を複合させ非トレーサ粒子可視化検出を実現する。
【００２９】
図１中の６、光学系切換え部の出し入れで２１、顕微光学拡大系に光学像を導入マクロに評価する、または７，偏光顕微拡大系に光学像を導入使用する。
【００３０】
同様に上記ＰＩＶ法による研磨液ながれ計測に加え、研磨液体流に蛍光発光色素を混入、前記レーザー励起蛍光法の手法で、レーザー入射強度を一定にし、検出色素の蛍光強度の比を時系列に検出、事前に計測した参照蛍光強度を利用して温度を比較計測する。そのようにして研磨液を供給しながら研磨材を揺動研磨する際に発生する研磨界面における温度上昇変化を検出評価する事が出来、且つ検出値の出力に応じて研磨界面部に供給される研磨液量を供給装置４で増量制御調整し、温度上昇を押さえている、研磨液供給を制御する手段において、研磨パッド等工具面上、中心部または周辺から研磨部材に研磨液を正しく揺動中心に横切る方向に吐出供給する様に細長いガイドを研磨ヘッド部の中心または周辺に設け供給制御する機能を有する研磨工具および研磨装置、上記手法により、前記研磨液ながれ可視化と同じ方法で温度変化上昇直接的に計測出来またながれ計測と複合計測が可能となり研磨プロセス現象の分析評価レベルが向上する。
【００３１】
本実施の形態によれば、従来例に比べて、微細な低コントラストな微粒子計測が可能と共に、可視化画像より温度分布測定が複合計測出来、また研磨パッド等による不要な背景光ノイズが除去されるため、安定した計測が可能となり、直接的かつ鮮明に研磨状態を可視化し、画像処理による計測データの信頼性も大幅に向上させることが出来る共に、複合同時計測による研磨プロセス検出評価レベルがＵｐする。
【００３２】
【発明の効果】
本発明は上述のとおり構成されているので、以下に記載するような効果を奏する。
【００３３】
オンマシン、リアルタイムでしかも高精度に研磨進行状況を計測、監視し、画像処理による研磨プロセスの分析評価、研磨液ながれの計測および研磨面内温度分布の同時複合計測および調整、非トレーサ粒子微細砥粒の検出等を的確に行なうことが出来、露光装置の光学材料等を研磨する高精度な研磨装置において、研磨特性を大幅に改善するとともに、研磨加工における時間的ロスを低減し、レンズ等の生産性向上に貢献できる。
【図面の簡単な説明】
【図１】この装置の実施の形態を示す説明ブロック図である。
【図２】実施形態による研磨装置を示すイメージ図である。
【図３】研磨液およびトレーサ粒子供給研磨工具実施例である。
【符号の説明】
１ 研磨工具（パッド）
２ ホルダー
３ 研磨揺動軸
４ 蛍光トレーサー粒子および研磨液供給制御装置
５ リニアモータガイド部
６ 光学系切換え部
７ 偏光顕微拡大光学系部
１０ 照射部
１１ レーザー発振器
１２ 高速光シャッター
１３ コリメーター
１４ 鏡筒
１５ 照射部ステージ
２０ 可視化計測部
２１ 顕微拡大光学系
２２ ＣＣＤカメラ
２３ 画像処理装置
２４ 同期制御回路
２５ 計測部ステージ
Ｌ１ 研磨液
Ｍ１ 研磨装置
Ｓ１ 研磨可視化検出装置部
Ｗ１ 研磨ワーク[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polishing apparatus for polishing a high-quality optical material used in a semiconductor manufacturing apparatus or the like, which stably measures, monitors, and evaluates a polishing state (polishing progress) during operation of the apparatus with high accuracy, and performs polishing. The present invention relates to a polishing visualization detection method, a polishing liquid flow, a temperature distribution measuring method, and a polishing apparatus capable of accurately measuring and controlling a temperature distribution and the like generated by a flow of a polishing liquid at an interface and friction with an abrasive. It is.
[0002]
[Prior art]
In recent years, along with the high integration of semiconductor processes, the quality of optical materials used for exposure apparatuses and the like has been required to be improved, and the performance of polishing apparatuses used for manufacturing lenses and the like has also been required to have higher quality.
[0003]
Conventionally, a polishing process is performed by a polishing tool (polishing pad) with a polishing liquid and an abrasive interposed. Since the processing surface (polishing surface) of the material to be polished is in contact with the polishing tool, it is not easy to visualize, observe, measure, and evaluate the progress of polishing during polishing.
[0004]
As for the polishing process under special conditions in the polishing liquid, there are some parts that have not yet been analyzed and elucidated sufficiently in terms of phenomena, while the state of various parameters on the polished surface during processing has an adverse effect on polishing characteristics. It is known to have a significant effect.
[0005]
Here, in order to know the direct effect on the working interface, which is considered to be one of the factors for evaluating the polishing process, the visualization measurement of the flow of the polishing liquid, the temperature generated by friction with the abrasive, etc. and the progress of the fixing of the polishing tool A method for measuring, observing, and monitoring various processing parameters such as the state and dispersion of abrasive grains, and a long and narrow guide that supplies the polishing liquid from the center of the surface of the polishing pad to the polishing member in a direction that crosses the polishing liquid correctly, stabilizes polishing processing efficiency. Let it.
[0006]
In general, when measuring the fluid velocity, the LDV method (Laser Doppler Velocimeter flow meter) is well known, and there are commercially available products which are widely used.
[0007]
The LDV method is a method in which a moving object is irradiated with laser light, and the moving speed is measured using an effect (Doppler effect) in which the frequency of scattered light from the moving object shifts in proportion to the moving speed of the moving object. And Japanese Patent Application Laid-Open No. 5-18982 and a surface blood flow measuring device (Japanese Patent Application Laid-Open No. 5-1501) are used as flow velocity measuring methods.
[0008]
Also, PIV (Particle Image Velocimetry) using laser-excited fluorescence is often used as a fluid velocity measurement method. The PIV method irradiates a fluid supplied with tracer particles with an excitation light source such as a laser and emits light from the fluid particles. This is a method in which the emitted scattered light is received by a CCD or the like, and image processing is performed to visualize and measure the velocity of the fluid. JP-A-5-297014 and JP-A-8-211087 are reported as flow measurement methods for objects. Have been.
[0009]
In addition, the temperature rise caused by friction with the abrasive, wear or damage of the tool, etc., and the temperature measurement method generally uses an infrared radiation thermometer using an infrared camera to measure the temperature distribution in the surface of the abrasive tool or the abrasive. In general, a method of obtaining a temperature and a method of using a thermocouple have been used (for example, Japanese Patent Application Laid-Open No. 7-94452 and Japanese Patent Application Laid-Open No. 11-104955). It is difficult to directly measure the temperature at the required location, and it is difficult to obtain a sufficient response speed because it is difficult to obtain a sufficient response speed because it is a measurement of the place where the thermocouple near the polishing part is connected. Has been pointed out.
[0010]
[Problems to be solved by the invention]
In the LDV method, since two lasers are incident and crossed, the observation point can be observed only at one intersection of the lasers, so that there is a problem that the flow velocity distribution cannot be measured.
[0011]
This method can be used in a transparent state of the fluid, but cannot be measured in a turbid state because the detection noise SNR is poor and cannot be used in a turbid state such as an abrasive in a polishing liquid.
[0012]
Also, PIV (Particle Image Velocimetry) using laser-excited fluorescence is often used, but as a detection tracer, it is possible to measure macroscopic flow by detecting only the emission wavelength of fluorescent particles mixed in the polishing liquid, but It is difficult to detect and detect fine particles with low luminous sensitivity and observation and detection of actual abrasive grains mixed in the polishing liquid due to problems such as background noise SNR of a polishing tool or the like as in the LDV method. In addition, in order to obtain temperature information from a visualized image, a method of obtaining a temperature distribution in a polishing tool or an abrasive material surface using an infrared radiation thermometer generally using an infrared camera as described above is performed. It has been pointed out that it is difficult to accurately measure a change in temperature, to perform a direct evaluation, and to obtain a sufficient response speed.
[0013]
The present invention has been made in view of the above-mentioned unresolved problems of the related art, and visualizes and measures the various information in the progress of polishing, monitors and analyzes and evaluates a polishing process during polishing, polishing temperature. It is an object of the present invention to provide a polishing visualization detection method, a polishing apparatus, and a polishing tool capable of performing measurement adjustment and the like with high accuracy.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, a polishing visualization detection method of the present invention is a polishing visualization detection method for detecting a polishing progress state in a polishing apparatus, and a method for macroscopically (macroscopically) visualizing and measuring polishing process information. The following method is used to enable micro (microscopic) observation for visualization observation of fine abrasive grains at the polishing interface.
[0015]
The approach of the polishing liquid to the polishing friction interface, the macroscopic visual field is required for flow observation, and the conventional optical microscopic magnification system is used for macroscopic detection, and fluorescent particles of about 2 to 6 microns are used as tracers, Irradiate the excitation light source to remove the background light noise of the polishing tool, etc., observe the fluorescence generated by the tracer particles, take in the image in time series to the image processing device, digitally process the obtained fluorescent particle image, and polish By analyzing individual fluorescent particles injected into the surface flow field, the polishing liquid flow is visualized.
[0016]
However, in the flow of a mixed dispersion of non-tracer particles such as an abrasive such as a polishing liquid and actual abrasive particles, the above-mentioned optical microscopic enlargement system uses fine fluorescent particles or actual abrasive particles or fine abrasive particles in the progress of polishing and fixing. It cannot be used because the contrast is so small that resolution performance cannot be obtained for visualization detection, etc.Therefore, the crystal structure can be observed with the observation optical system, and the boundary and irregularity change of the tissues with different refractive indexes can be observed as color or contrast of light and dark. The polarization micro-magnification system is adopted, and the conventional PIV method is extended to combine macro-evaluation on the polished surface with micro-evaluation detection such as observation of fine abrasive grains to realize non-tracer particle visualization detection. For temperature measurement, instead of the conventional infrared radiation thermometer, microencapsulated temperature-sensitive particles are used for the tracer.Similar to flow measurement, temperature information is obtained from emission luminescence intensity. Simultaneous measurement of the evaluation becomes possible, and the analysis of the polishing process phenomenon is improved.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to the drawings.
[0018]
Figure 1 shows an embodiment, the polishing apparatus M 1 causes the straight swung in the direction indicated by the arrow R the polishing pad 1 constituting a polishing tool in a few Hz. Transparent optical material holder 2 workpiece W 1 is held is (material to be polished), are polished by the polishing tool (pad) 1 of the upper surface thereof. The lower surface of the holder 2 is partitioned with a quartz glass material so that the work W 1 is irradiated with light so that the polished surface can be observed from below, and the polishing liquid L 1 containing the abrasive and the fluorescent tracer particles does not leak. Have been.
[0019]
The polishing swinging shaft 3 is provided with a fluorescent tracer particle supply and polishing liquid supply device 4 which is a supply means of the fluorescent particles and the polishing liquid, and a fluorescent tracer particle which is a fluorescent particle made of a fluorescent substance is periodically provided therefrom. It is supplied to the polishing liquid L 1.
[0020]
At the bottom of the polishing apparatus M 1, is polished visualized detector S 1 is disposed, the configuration is as follows.
[0021]
An irradiating unit 10 that irradiates the fluorescent tracer particles with light (illumination light) is a shutter that opens and closes in synchronization with the oscillation of the polishing pad 1 by the polishing oscillation shaft 3 and the laser oscillator 11 that is the light source. It comprises a high-speed light AO shutter 12 as a means, a collimator 13 for expanding a laser beam aperture, a lens barrel 14 holding the collimator 13, and an irradiation section stage 15 which is an XYZθ stage for controlling the position of the entire irradiation section 10. Is done.
[0022]
The visualization measurement unit 20 is attached directly below the observation window made of the above-mentioned quartz glass material, and is an enlargement optical system 21 for enlarging the particle image so that the fluorescent tracer particles visualized by the irradiation of the laser beam can be observed. Having. The magnifying optical system 21 can be arbitrarily selected and mounted from a microscope magnifying system to a macro lens magnifying system, and a wavelength filter for removing a visualized image background scattering noise is mounted. Polishing process information can be captured macroscopically.
[0023]
The enlarged visualized particle image is captured by a CCD camera 22 as an imaging means as a high-resolution image of 1000 × 1000 pixels into an image processing device 23 having an image reading device and a computer. Further, in conjunction with the high-speed light AO shutter 12 of the irradiation unit 10, only the fluorescence of the fluorescent tracer particles to which light energy has been applied is selected by the wavelength filter and taken into the CCD camera 22, and synchronous control for taking an image into the camera is performed. There are provided a synchronization control circuit 24 as a means, and a measuring unit stage 25 which is an XYZθ stage for controlling the position of the magnifying optical system 21 and the CCD camera 22.
[0024]
When high-speed optical AO shutter 12 is opened, the laser beam is irradiated onto the polishing surface of the polishing pad 1 and the workpiece W 1, the reflected scattered light from the polishing surface is emitted as fluorescent tracer particles. The synchronization control circuit 24 inputs the CCD charge clear signal to the image processing device 23 which reads the image of the CCD camera 22 at the same time as the high-speed light AO shutter 12 is closed, that is, in synchronization with the light-shielding timing. The fluorescence of the tracer particles is observed and a signal is input to the CCD camera 22 as an image. In this way, noise due to scattered light from the polishing pad 1 or the like is removed, and only the fluorescence from the fluorescent tracer particles is read into the image processing device 23.
[0025]
In this way, only the fluorescent particle images from the fluorescent tracer particles are sequentially captured in time series as an image, the progress of polishing is monitored on the monitor screen, the image data is image-processed, and the tracer particles in the polishing liquid are tracked and polished. Visualize, measure and observe the liquid flow image.
[0026]
Immediately after the start of polishing, particles between the workpiece to be polished and the polishing pad remain uneven, the particle density distribution becomes mottled, and the flow velocity and flow direction change in a complicated manner. However, as the polishing proceeds, the polished surface is flattened and the density distribution of the particles becomes uniform. Similarly, the flow velocity and flow direction of the particles are uniformed.
[0027]
As described above, by performing image processing on the temporal change of the fluorescent particle image, the polishing progress state can be measured and monitored on-machine. Further, the polishing progress state can be measured, monitored, and evaluated by successively comparing the polishing progress pattern based on known data stored in advance in the memory of the computer with the image processing pattern based on the measurement data of the captured image.
[0028]
On the other hand, in the flow of the mixed dispersion of non-tracer particles such as the polishing agent and the real abrasive grains described above in the optical microscopic magnifying system, the fine fluorescent particles and the real abrasive grains, etc. For the visualization detection of the behavior of fine abrasive grains in the situation, the contrast is small and the resolution performance is not obtained and it can not be used with the normal enlargement method, so the observation optical system can observe the crystal structure and the structure with different refractive index The polarization micro-enlargement system that can observe the boundary and unevenness of the surface as color and contrast of light and dark is adopted. The conventional PIV method is extended to combine the macro evaluation on the polished surface and the micro evaluation such as the observation of fine abrasive grains. To realize non-tracer particle visualization detection.
[0029]
In FIG. 1, 6, the optical system switching unit is inserted / exited 21, and the optical image is introduced into the microscopic optical magnifying system. The macro image is evaluated, or 7, the optical image is introduced into the polarized microscopic magnifying system.
[0030]
Similarly, in addition to the flow measurement of the polishing liquid by the PIV method, a fluorescent dye is mixed in the polishing liquid stream, and the laser excitation fluorescence method is used to make the laser incident intensity constant and to change the ratio of the fluorescence intensity of the detection dye in time series. The temperature is compared and measured using the reference fluorescence intensity measured and detected in advance. In this way, it is possible to detect and evaluate a change in temperature rise at the polishing interface that occurs when the polishing material is oscillated while supplying the polishing liquid, and to be supplied to the polishing interface in accordance with the output of the detected value. In the means for controlling the supply of the polishing liquid by controlling the amount of the polishing liquid to be increased and controlled by the supply device 4 and suppressing the temperature rise, the polishing liquid is correctly swung from the surface of the tool such as a polishing pad, the center or the periphery to the polishing member. A polishing tool and a polishing apparatus having a function of controlling the supply by providing an elongated guide at the center or periphery of the polishing head so as to discharge and supply in a direction transverse to the center, the temperature change rises in the same manner as the polishing liquid flow visualization by the above method. Direct measurement, flow measurement and composite measurement become possible, and the level of analysis and evaluation of polishing process phenomena is improved.
[0031]
According to the present embodiment, it is possible to perform fine and low-contrast fine particle measurement as compared with the conventional example, to perform combined measurement of temperature distribution measurement from a visualized image, and to remove unnecessary background light noise due to a polishing pad or the like. Therefore, stable measurement is possible, the polishing state can be visualized directly and clearly, the reliability of the measurement data by image processing can be greatly improved, and the evaluation level of the polishing process detection by composite simultaneous measurement increases. .
[0032]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
[0033]
On-machine, real-time and highly accurate measurement and monitoring of the progress of polishing, analysis and evaluation of the polishing process by image processing, measurement of the flow of the polishing liquid, simultaneous measurement and adjustment of the temperature distribution in the polishing surface, fine grinding of non-tracer particles In a high-precision polishing machine for polishing optical materials and the like in an exposure apparatus, the polishing characteristics can be significantly improved, the time loss in polishing processing can be reduced, and the time loss in polishing can be reduced. It can contribute to productivity improvement.
[Brief description of the drawings]
FIG. 1 is an explanatory block diagram showing an embodiment of this apparatus.
FIG. 2 is an image diagram showing a polishing apparatus according to an embodiment.
FIG. 3 is an embodiment of a polishing tool for supplying a polishing liquid and tracer particles.
[Explanation of symbols]
1 polishing tool (pad)
2 Holder 3 Polishing swing axis 4 Fluorescent tracer particle and polishing liquid supply control device 5 Linear motor guide unit 6 Optical system switching unit 7 Polarized microscopic magnifying optical system unit 10 Irradiation unit 11 Laser oscillator 12 High-speed optical shutter 13 Collimator 14 Lens tube 15 Irradiation unit stage 20 Visualization measurement unit 21 Microscopic magnification optical system 22 CCD camera 23 Image processing unit 24 Synchronous control circuit 25 Measurement unit stage L1 Polishing liquid M1 Polishing device S1 Polishing visualization detection unit W1 Polishing work
