JP3789296B2

JP3789296B2 - Polishing liquid production equipment

Info

Publication number: JP3789296B2
Application number: JP2000351096A
Authority: JP
Inventors: 郁近藤; 直紀津田; 紀博高崎; 嘉文板東; 増美日野; 堅洋宮田
Original assignee: Rion Co Ltd; Mitsubishi Chemical Engineering Corp
Current assignee: Rion Co Ltd; Mitsubishi Chemical Engineering Corp
Priority date: 2000-11-17
Filing date: 2000-11-17
Publication date: 2006-06-21
Anticipated expiration: 2020-11-17
Also published as: TW572810B; CN1299878C; CN1356369A; JP2002154056A

Description

【０００１】
【発明の属する技術分野】
本発明は、研磨液の製造装置に関するものであり、詳しくは、例えば、半導体デバイス製造プロセスの研磨加工に使用される化学機械研磨用の研磨液を調製する研磨液の製造装置であって、研磨液における所定粒径以上の粒径の砥粒の発生をインラインで連続的に管理できる研磨液の製造装置に関するものである。
【０００２】
【従来の技術】
半導体デバイスは、一層の高集積化、高速化および低消費電力化が要求されており、その製造プロセスにおいては、中間工程でウエハに形成されるメタル配線や層間絶縁膜の表面をより平坦化するため、例えば、シリカ系の研磨液（ＣＭＰスラリー）を使用し、ウエハの表面に化学機械研磨を施している。また、昨今は、デバイスの量産化ならびに研磨液の組成管理の問題から、上記の様な研磨液を研磨工程において一貫して製造している。研磨液を製造する場合は、正確なポリッシングレートを得るため、厳密に砥粒濃度を管理する必要がある。そして、研磨液においては、漸次、砥粒の凝集が進行し、凝集した大粒の砥粒がウエハに対するスクラッチの発生の一因となる虞があるため、研磨液中の砥粒の大きさの管理がより重要になっている。
【０００３】
研磨液の製造においては、得られる研磨液をサンプリングして純水で希釈した後、一定波長の光を照射し、その透過光や散乱光の強度を測定することにより、研磨液中の大きな粒径の砥粒の数を計測している。サンプリングによって研磨液を管理する理由は次の通りである。すなわち、研磨液中の砥粒を製造ライン上で直接測定しようとすると、ポンプの脈動などによる流量変動が影響するため、正確に砥粒の数を計測できない。また、上記の様なシリカ系研磨液は、例えば、平均粒径で０．２μｍ程度のシリカ粒子が１０¹³個／ｍｌと非常に高濃度であり且つ問題となる粒径の大きな砥粒の数が少ない。従って、仮に、粒径が３μｍ以上に凝集した砥粒を検出する場合でも、適正な粒径の砥粒による光の減衰により、直接測定によっては大粒径の砥粒による減衰を検出し難い。
【０００４】
【発明が解決しようとする課題】
ところで、上記の様な研磨液中の大粒径の砥粒の検出には、比較的長い時間を要するため、実際、サンプリングされた研磨液に対し、使用される研磨液に差異が生じる。すなわち、使用される研磨液は、サンプリング時よりも更に凝集が進行するために大粒径の砥粒をより多く含んでおり、その結果、研磨加工においては、予想外に、ウエハにスクラッチが発生することがある。
【０００５】
本発明は、上記の実情に鑑みてなされたものであり、その目的は、半導体デバイス製造プロセスの研磨加工に使用される化学機械研磨用の研磨液などを調製する研磨液の製造装置であって、研磨液における所定粒径以上の粒径の砥粒の発生をインラインで連続的に且つ高精度に管理できる研磨液の製造装置を提供することにある。
【０００６】
【課題を解決するための手段】
上記の課題を解決するため、本発明に係る研磨液の製造装置は、主に純水および砥粒から成る研磨液を調製する研磨液の製造装置であって、供給されたスラリー原液と純水を混合し、一定の砥粒濃度の研磨液を調製する調製槽と、調製された研磨液を循環させ、当該研磨液の懸濁状態を維持する研磨液循環装置とを備え、かつ、前記研磨液循環装置は、研磨液循環用の管路および流量調整可能なそのバイパス管路を含み、前記バイパス管路には、所定粒径以上の粒径の砥粒を検出し且つその数を計測する研磨液監視用のパーティクル検出器が設けられ、当該パーティクル検出器は、研磨液が通過するフローセルに一定波長の光を照射し、前記所定粒径以上の粒径の砥粒による透過光の減衰を検出する光遮断方式の検出器であり、前記フローセルは、前記バイパス管路の流量調整によって一定の流速で研磨液が通過可能に構成されていることを特徴とする。
【０００７】
すなわち、上記の製造装置においては、調製槽によって一定の砥粒濃度の研磨液を混合調製した後、研磨液循環装置によって研磨液を循環させながらその懸濁状態を維持する。また、研磨液循環用の管路のバイパス管路に設けられた研磨液監視用のパーティクル検出器は、研磨液が通過するフローセルに一定波長の光を照射し、所定粒径以上の粒径の砥粒による透過光の減衰を検出する。その際、流量調整可能なバイパス管路にパーティクル検出器が設けられた構造、および、バイパス管路の流量調整によって一定の流速で研磨液が通過可能なフローセルの構造は、フローセルにおける研磨液の流量が制限されると共に、研磨液循環用の管路に生じた脈動などによる影響がなく、しかも、フローセルに流れる研磨液中の所定粒径未満の砥粒の絶対数が低減されるため、所定粒径未満の粒径の砥粒による透過光の減衰と、所定粒径以上の粒径の砥粒による透過光の減衰とを分離できる。
【０００８】
また、上記の製造装置において、パーティクル検出器には、所定粒径以上の粒径の砥粒による透過光の減衰を検出する際、研磨液中の所定粒径未満の砥粒による感度低下を補正する校正機能が備えられているのが好ましく、斯かる校正機能は、所定粒径以上の粒径の砥粒による透過光の減衰に対する検出感度を高めることが出来る。
【０００９】
また、上記の製造装置のより好ましい態様においては、研磨装置により高品位の研磨液を供給するため、研磨液循環装置の後段には、当該研磨液循環装置によって循環される研磨液を研磨装置へ供給する研磨液供給装置が備えられ、かつ、当該研磨液供給装置は、研磨液供給用の管路および流量調整可能なそのバイパス管路を含み、前記バイパス管路には、所定粒径以上の粒径の砥粒を検出し且つその数を計測する研磨液監視用のパーティクル検出器が設けられ、当該パーティクル検出器は、研磨液が通過するフローセルに一定波長の光を照射し、前記所定粒径以上の粒径の砥粒による透過光の減衰を検出する光遮断方式の検出器であり、前記フローセルは、前記バイパス管路の流量調整によって一定の流速で研磨液が通過可能に構成されている。
【００１０】
すなわち、上記の製造装置においては、研磨液循環装置によって循環される研磨液を研磨装置へ研磨液供給装置によって供給し、また、研磨液供給用の管路のバイパス管路に設けられた上記と同様の研磨液監視用のパーティクル検出器は、研磨液が通過するフローセルに一定波長の光を照射し、所定粒径以上の粒径の砥粒による透過光の減衰を検出する。その際、上記と同様に、研磨液供給用の流量調整可能なバイパス管路にパーティクル検出器が設けられた構造、および、バイパス管路の流量調整によって一定の流速で研磨液が通過可能なフローセルの構造は、フローセルにおける研磨液の流量が制限されると共に、研磨液供給用の管路に生じた脈動などによる影響がなく、しかも、フローセルに流れる研磨液中の所定粒径未満の砥粒の絶対数が低減されるため、所定粒径未満の粒径の砥粒による透過光の減衰と、所定粒径以上の粒径の砥粒による透過光の減衰とを分離できる。
【００１１】
また、上記の各態様の製造装置において、研磨液監視用のパーティクル検出器には、所定粒径以上の粒径の砥粒による透過光の減衰を検出する際、研磨液中の所定粒径未満の砥粒による感度低下を補正する校正機能が備えられているのが好ましく、斯かる校正機能は、所定粒径以上の粒径の砥粒による透過光の減衰に対する検出感度を高めることが出来る。
【００１２】
【発明の実施の形態】
本発明に係る研磨液の製造装置の一実施形態を図面に基づいて説明する。図１は、本発明に係る研磨液の製造装置の概要を示す系統図である。図２は、本発明に係る研磨液の製造装置に適用されるパーティクル検出器の原理を一部破断して示す図であり、分図（ａ）は側面図、分図（ｂ）は平面図である。また、図３は、パーティクル検出器のセンサーからの出力および変換された制御用のパルス信号の例を示すグラフである。なお、図１の系統図においては、弁類や計装機器などを省略している。また、以下の実施形態の説明においては、適宜、研磨液の製造装置を単に「製造装置」と略記する。
【００１３】
本発明の製造装置は、主に純水および砥粒から成る研磨液、典型的には、半導体デバイスの研磨に適用される化学機械研磨用の例えばシリカ系研磨液（ＣＭＰスラリー）を調製する研磨液の製造装置であり、オンサイトで高品位の研磨液を製造し得る装置である。
【００１４】
シリカ系研磨液の場合、その主成分は、ヒュームドシリカの砥粒と純水であり、砥粒の粒径は、通常は５μｍ未満、好ましくは３μｍ未満、より好ましくは０．１〜２μｍであり、また、砥粒の含有量は、一般的には１０〜３０重量％である。また、上記の研磨液には、必要に応じて添加剤が添加されてもよい。添加剤としては、メタル配線の表面を研磨する場合やプラグを除去する場合、これらを酸化し得る成分であればよく、一般的には過酸化水素が使用される。また、シリコン層を研磨する場合は、水酸化カリウム等のアルカリが添加剤として使用される。これらの酸またはアルカリは、後述する添加剤供給装置（Ｌ３）を通じて水溶液として添加される。
【００１５】
本発明の製造装置は、図１に示す様に、供給されたスラリー原液、すなわち、粒径が例えば３μｍ未満の砥粒を含むスラリー原液と純水を混合し、一定の砥粒濃度の研磨液を調製する調製槽（２）と、調製された研磨液を循環させ、当該研磨液の懸濁状態を維持する研磨液循環装置（Ｌ４）とを少なくとも備えている。
【００１６】
通常、調製槽（２）は、原液供給装置（Ｌ１）によって一定濃度のスラリー原液が供給され、純水供給装置（Ｌ２）（図示省略）によって純水が供給される様になされている。また、調製槽（２）の後段には、調製槽（２）にて調製された研磨液を貯留する研磨液槽（３）が備えられており、上記の研磨液循環装置（Ｌ４）は、研磨液槽（３）の研磨液を循環可能に構成される。更に、研磨液槽（３）は、添加剤供給装置（Ｌ３）によって上記の様な添加剤が供給可能に構成される。
【００１７】
原液供給装置（Ｌ１）は、原液槽（１）から調製槽（２）にスラリー原液を圧送する装置であり、原液槽（１）から調製槽（２）へ至る配管（５１）、ベローズ方式などの定流量ポンプ（図示省略）等から構成される。原液槽（１）は、スラリー原液を調製槽（２）に供給するための貯槽であり、耐腐食性を備えた固定式容器または可搬式容器によって構成される。
【００１８】
原液槽（１）は、系外から搬入されるスラリー原液の搬送用容器に接続可能な配管（図示省略）を備えており、斯かる配管を通じ、窒素などの不活性ガスによってスラリー原液が搬送用容器から圧送される様になされている。また、原液槽（１）には、空気との接触を防止するため、不活性ガスの供給配管（図示省略）が付設される。
【００１９】
調製槽（２）は、研磨液の濃度を所定濃度に調整し且つ濃度調整された研磨液を貯留するための貯槽である。例えば、調製槽（２）は、耐腐食性を高めるため、フッ素樹脂でライニングした容器によって構成される。調製槽（２）には、受け入れるスラリー原液や純水の重量を計量するための計量器、液量を計測するための光式、導電率式、静電容量式などのポイント測定可能な液面計（図示省略）が設けられる。また、空気との接触を防止するため、調製槽（２）には、不活性ガスの供給配管（図示省略）が付設される。
【００２０】
純水供給装置（Ｌ２）は、調製槽（２）に希釈用の純水を供給する装置であり、イオン交換樹脂などによって超純水を分離精製する公知の純水製造装置から調製槽（２）に至る管路（５２）を備えており、通常、純水製造装置に付設されたポンプを利用し、純水製造装置で製造された純水を調製槽（２）へ圧送する様になされている。
【００２１】
製造量が小規模の場合は、調製槽（２）で調製された研磨液を研磨液循環装置（Ｌ４）によって直ちに循環させ且つ研磨装置（９）（定盤装置）に供給する様になされていてもよいが、複数の研磨装置（９）に安定して研磨液を供給するため、通常は、調製槽（２）の後段に上記の研磨液槽（３）が配置される。図１に例示した装置においては、調製槽（２）で混合調製された研磨液をポンプ（４１）及び管路（５３）によって研磨液槽（３）へ移送する様になされている。なお、図中の管路（５４）は、必要に応じて研磨液の濃度をモニターし且つ調製槽（２）へ研磨液を戻すための返流用の管路である。
【００２２】
研磨液槽（４）は、調整された研磨液を外部の研磨装置へ供給するための貯槽であり、そして、上記の様な酸またはアルカリの添加剤が水溶液で供給されるため、例えば、フッ素樹脂でライニングされた耐腐食性の容器によって構成される。研磨液槽（４）には、研磨液の液量や添加剤の添加量を計測するため、光式、導電率式、静電容量式などのポイント測定可能な液面計（図示省略）が設けられる。また、空気との接触を防止するため、研磨液槽（４）には、不活性ガスの供給用配管（図示省略）が付設される。
【００２３】
研磨液槽（４）に添加剤を供給するための添加剤供給装置（Ｌ３）は、別途設けられた添加剤槽（図示省略）から研磨液槽（３）に添加剤を圧送する装置であり、添加剤槽から添加剤を取り出すための管路（図示省略）、流量が可変で且つ一定流量に制御可能なマグネットポンプ等の送液用の定量ポンプ（図示省略）、および、研磨液槽（３）へ添加剤を供給する管路（５５）等から成る。
【００２４】
更に、研磨液槽（４）においては、砥粒成分の沈降や凝集を防止するため、噴流によって研磨液を常時撹拌する撹拌機構が設けられる。撹拌機構は、撹拌羽根などの回転装置によって構成されてもよいが、例えば、撹拌機構は、後述する研磨液循環装置（Ｌ４）における管路（５６）の返流側の先端、すなわち、研磨液槽（３）内に挿入された配管先端に付設されたジェットノズル（図示せず）によって構成される。斯かるジェットノズルは、管路（５６）の返流側先端から噴出する駆動加圧流体としての研磨液の噴出エネルギーにより、研磨液槽（３）の底部近傍に噴流を発生させることが出来る。
【００２５】
なお、図示しないが、本発明の製造装置においては、研磨液と添加剤の混合効率を高めるため、調製槽（２）と研磨液槽（３）の間に混合槽を配置し、調製槽（２）から供給される研磨液と添加剤供給装置（Ｌ３）から供給される添加剤とを混合槽において予め混合した後、添加剤の添加された研磨液を研磨液槽（３）で貯留する様になされていてもよい。
【００２６】
研磨液循環装置（Ｌ４）は、調製された研磨液の懸濁状態を一様に維持し且つ研磨液における砥粒の凝集を低減すると共に、後述の研磨液供給装置（Ｌ５）へ直ちに研磨液を供給するために設けられており、研磨液槽（３）の研磨液を循環可能に構成される。すなわち、研磨液循環装置（Ｌ４）は、研磨液槽（３）から研磨液を取り出し且つ研磨液槽（３）へ研磨液を戻すための研磨液循環用の管路（５６）、および、研磨液を送るポンプ（４２）等から構成される。
【００２７】
研磨液は、前述の様に、粒径が例えば３μｍ未満の砥粒を分散させた液体であるが、時間の経過に伴って砥粒の凝集が進行し、粒径が３μｍ以上の大きな砥粒（以下、適宜「大粒径の砥粒」と言う。）に成長する。従って、研磨装置（９）にて研磨液を使用した際、大粒径の砥粒によるウエハのスクラッチを防止するため、研磨液循環用の管路（５６）には、予め設定された所定粒径以上の粒径の砥粒、具体的には例えば３μｍ以上の粒径の砥粒を捕捉する循環路用のフィルタ（６１）が後述するパーティクル検出器（７）の上流側に配置される。
【００２８】
斯かるフィルタ（６１）としては、孔径が１．０〜５．０μｍ程度に設計されたポリプロピレン製のデプスタイプの濾材を備えた通常の流体用フィルタが使用される。なお、研磨液循環装置（Ｌ４）は、研磨液槽（３）の添加剤濃度を管理するため、バイパス配管（図示省略）を通じて濃度測定装置（図示省略）へ研磨液を供給可能になされていてもよい。
【００２９】
本発明の製造装置は、研磨液中の大粒径の砥粒の発生ならびにその数を研磨液循環装置（Ｌ４）において管理するため、研磨液循環装置（Ｌ４）の研磨液循環用の管路（５６）には、流量調整弁（図示省略）やオリフィス等によって流量調整可能なバイパス管路（５６１）が備えられており、そして、斯かるバイパス管路（５６１）には、前述した所定粒径以上の粒径の砥粒、すなわち、予め設定された粒径以上の大きな砥粒、例えば３μｍ以上の粒径の砥粒を検出し且つその数を計測する研磨液監視用のパーティクル検出器（７）が設けられる。
【００３０】
前述した通り、シリカ系研磨液における適性な砥粒の平均的粒径を例えば３μｍ未満とした場合、凝集の進行により粒径は３μｍ以上、場合によっては数μｍ以上になることがあるが、斯かる大粒径の砥粒の数は、研磨液中の適正な粒径の砥粒の数に比べて極めて少数である。例えば、研磨液中の適正な砥粒の平均粒径が０．２μｍ程度の場合、その数が１０¹³個／ｍｌであるのに対し、スクラッチの原因となる大粒径の砥粒の数は１０〜１０００個／ｍｌ程度である。そこで、パーティクル検出器（７）としては、研磨液が通過するフローセル（７４）に一定波長の光を照射し、所定粒径以上の粒径の砥粒による透過光の減衰を検出する光遮断方式の検出器が使用される。
【００３１】
光遮断方式の検出器の基本的な構造は公知であり、斯かる検出器は、透明なフローセルを流れる流体（スラリー）に光を照射し、受光素子によって透過光の光量を検出する構造を備え、フローセル中を通過した粒子による光の吸収、反射または散乱による光量の減少によって粒子の大きさを計測し、また、パルスとして得られる光量の変化の回数によって粒子の数を計測する様になされている。
【００３２】
具体的には、図２に示す様に、パーティクル検出器（７）の主要部は、電源回路（７１）によって供給される電力により一定波長の光を発光するタングステンランプ、発光ダイオード、半導体レーザー等の光源（７２）、光源（７２）から照射された光を例えば扁平な帯状の光束に集光する集光レンズ（７３）、石英ガラス等の透明性材料によって例えば方形状断面の筒状に形成されたフローセル（７４）、フローセル（７４）を通過した光源（７２）の透過光の強度を検出するフォトダイオード、光アレイ等の受光素子（７５）、受光素子（７５）の出力信号を増幅する増幅器（７６）、および、当該受光素子の信号を演算処理する演算処理手段（記憶・演算素子を含む演算回路）等から成る。
【００３３】
一般的に、研磨液中の大粒径の砥粒の計測においては、前述の通り、砥粒濃度が例えば１０〜３０重量％の研磨液中の極めて少数の砥粒を検出しなければならない。従って、検出対象の大粒径の砥粒の粒径の下限値の設定によっては、適正な砥粒による光の吸収、反射または散乱による影響（ノイズ）が大きく、大粒径の砥粒を正確に検出し難い。更に、ポンプ等の機器によって流体に脈動がある場合には、粒子数を正確に計測できない。
【００３４】
これに対し、本発明においては、バイパス管路（５６１）によって流量が制限されたバイパス管路（５６１）にパーティクル検出器（７）を設けることにより、研磨液循環用の管路（５６）における脈動の影響を防止し、かつ、適正な粒径の砥粒による影響（ノイズ）を低減し、数の少ない大粒径の砥粒の正確な検出を可能にしている。すなわち、フローセル（７４）は、バイパス管路（５６１）の流量調整によって一定の流速で研磨液が通過可能に構成される。通常、フローセル（７４）における研磨液の流量は１〜５００ｍｌ／分に設定され、流速は０．１〜１ｍ／秒に設定される。また、一層正確に大粒径の砥粒を検出するため、フローセル（７４）における光の透過距離は、好ましくは０．１〜１００ｍｍに設定される。
【００３５】
更に、本発明の製造装置においては、循環する研磨液中の大粒径の砥粒を一層高精度に検出するため、パーティクル検出器（７）には、予め設定された所定粒径以上の粒径の砥粒による透過光の減衰を検出する際、研磨液中の所定粒径未満の砥粒（適正な粒径の砥粒）による感度低下を補正する校正機能が備えられている。斯かる校正機能は、通常、上記の演算処理手段に設けられる。
【００３６】
すなわち、パーティクル検出器（７）においては、図３（ａ）に示す様に、受光素子（７５）は、受光した光の信号をパルス信号として出力するが、上記の演算処理手段は、得られたパルス信号を図３（ｂ）に示す様な波形に波形処理した後、標準試料によって予め設定された下限の閾値電圧よりも高い信号を計数する様になされている。上記の標準試料としては、所定粒径未満の砥粒（例えば粒径が３μｍ未満の砥粒）を一定量（例えば１５重量％）含み且つ検出すべき粒径（例えば３μｍ）と同一の粒径のポリスチレンラテックス粒子を標準粒子として加えられた研磨液が使用される。
【００３７】
本発明の製造装置には、原液供給装置（Ｌ１）、調製槽（２）、純水供給装置（Ｌ２）、研磨液槽（３）、添加剤供給装置（Ｌ３）、研磨液循環装置（Ｌ４）、後述する研磨液供給装置（Ｌ５）の制御ならびに上記のパーティクル検出器（７）の検出信号に基づいて後述する警報の発報などを行うための制御装置（１０）が設けられる。斯かる制御装置（１０）は、各機器の信号をデジタル変換する入力装置、記憶手段を含むプログラムコントローラー又はコンピューター等の演算処理装置と、演算処理装置からの制御信号をアナログ変換する出力装置とから主に構成される。
【００３８】
次に、本発明の製造装置による研磨液の製造方法を説明する。本発明の製造装置においては、先ず、原液槽（１）から調製槽（２）へ一定砥粒濃度のスラリー原液を計量供給し、純水供給装置（Ｌ２）によって調製槽（２）へ純水を所定量計量供給した後、調製槽（２）において研磨液を混合調製する。その際、ポンプ（４１）及び管路（５４）を介し、調製槽（２）の研磨液を循環させつつ、管路（５４）に付設された濃度計測器によってスラリー濃度測定すると共に、測定結果に基づいてスラリー原液あるいは純水の供給量を微調整することにより、研磨液の砥粒濃度（スラリー濃度）を例えば１５重量％に調整する。
【００３９】
調製槽（２）にて調製された研磨液は、管路（５３）を通じて研磨液槽（３）へ供給する。次いで、研磨液槽（３）へ供給された研磨液に対し、添加剤供給装置（Ｌ３）から管路（５５）を通じ、前述の様な添加剤を必要に応じて供給する。そして、研磨液槽（３）に設けられた上記の撹拌機構によって添加剤を撹拌混合し、所定の砥粒濃度で且つ所定の添加剤濃度の研磨液を調製する。なお、添加剤の濃度は、研磨液循環装置（Ｌ４）の管路（５６）を流れる研磨液の一部を濃度測定装置に供給し、その測定結果に基づいて添加剤供給装置（Ｌ３）からの添加剤の供給量または管路（５３）から供給される研磨液の供給量を制御することによって調整する。
【００４０】
研磨液槽（３）にて最終的に調製された所定の組成の研磨液は、研磨液循環装置（Ｌ４）によって循環させる。すなわち、研磨液循環装置（Ｌ４）のポンプ（４２）及び管路（５６）を使用し、研磨液槽（３）から取り出した研磨液を再び研磨液槽（３）へ返流させることにより、研磨液における砥粒の均一な懸濁状態を維持する。また、その際、管路（５６）に介装されたフィルタ（６１）は、循環する研磨液において凝集の進行した所定粒径以上の大粒径の砥粒を捕捉する。これにより、大粒径の砥粒を略含まない研磨液を管路（５６）に循環させることが出来る。
【００４１】
ところで、研磨液中の上記の大粒径の砥粒は、研磨液槽（３）及び研磨液循環装置（Ｌ４）における滞留時間が長くなるほど増加し、また、フィルタ（６１）の機能低下によっても増加する。これに対し、本発明の製造装置においては、管路（５６）中の研磨液の一部をバイパス管路（５６１）に供給し、バイパス管路（５６１）の研磨液監視用のパーティクル検出器（７）によって研磨液を監視する。すなわち、バイパス管路（５６１）に設けられたパーティクル検出器（７）は、研磨液が通過するフローセル（７４）に一定波長の光を照射し、所定粒径以上の粒径の砥粒、例えば粒径が３μｍ以上の大粒径の砥粒による透過光の減衰を検出することにより、研磨液中の大粒径の砥粒の数を計測する。
【００４２】
その際、流量調整可能なバイパス管路（５６１）にパーティクル検出器（７）が設けられ、バイパス管路（５６１）の流量調整によって一定の流速で研磨液が通過可能なフローセル（７４）の構造は、フローセル（７４）における研磨液の流量が制限されると共に、研磨液循環用の管路（５６）に生じたポンプ等の機器の脈動などによる影響がなく、しかも、フローセル（７４）に流れる研磨液中の所定粒径未満の砥粒の絶対数が低減されるため、受光素子（７５）によって受光したフローセル（７４）の透過光を演算処理手段によって処理した場合、所定粒径未満の粒径の適正な砥粒（粒径が例えば３μｍ未満の砥粒）による透過光の減衰と、所定粒径以上の粒径の砥粒（粒径が例えば３μｍ以上の砥粒）による透過光の減衰とを分離でき、その結果、所定粒径以上の粒径の砥粒の数を正確に計測できる。
【００４３】
また、パーティクル検出器（７）に備えられた校正機能は、上記の大粒径の砥粒による透過光の減衰を検出する際、研磨液中の所定粒径未満の砥粒による感度低下を補正し、大粒径の砥粒による透過光の減衰に対する検出感度を一層高めることが出来る。従って、本発明の製造装置は、研磨液循環装置（Ｌ４）の管路（５６）を循環する研磨液において、所定粒径以上の大粒径の砥粒の発生およびその数をインラインで且つ連続的に、しかも、高精度に管理できる。
【００４４】
本発明の製造装置においては、得られる研磨液を上記の様にインラインで管理することにより、常に高品位の研磨液を研磨装置（９）へ供給できる。例えば、本発明の製造装置においては、パーティクル検出器（７）によって検出された所定粒径以上の粒径の砥粒の一定流量当りの数が管理限界を越えた際、警報を発報させる機能が備えられていてもよい。斯かる砥粒の数の管理機能および警報の発報機能は、通常、上記の制御装置（１０）に備えられる。また、上記の様な発報に伴い、研磨装置（９）への研磨液の供給を停止する様にしてもよい。更に、研磨液をインラインで管理することにより、フィルタ（６１）の機能が低下した時点で直ちにフィルタの濾材を交換でき、研磨装置（９）へ供給する研磨液を常に高い品質に維持できる。
【００４５】
また、図示しないが、本発明の製造装置において、循環用の管路（５６）には、フィルタ（６１）と並列に循環路用の第２のフィルタが配置されており、パーティクル検出器（７）によって検出された所定粒径以上の粒径の砥粒の一定流量当りの数が管理限界を越えた際、第２のフィルタ側へ流路を切替可能になされていてもよい。すなわち、所定粒径以上の砥粒を濾過するフィルタが管路（５６）に２系列並列に挿入されていることにより、フィルタ（６１）の機能が低下した場合、機能の低下していない第２のフィルタに直ちに切り替えることができ、運転を停止することなく、常に高い品質の研磨液を研磨装置（９）へ供給できる。
【００４６】
ところで、上記の様な研磨液循環装置（Ｌ４）には、通常、研磨装置へ研磨液を供給するための複数の管路が付設され、斯かる研磨液供給用の管路は、研磨装置の稼働に応じて管路中の仕切弁を制御されることにより、研磨装置へ研磨液を供給する様になされている。従って、研磨装置の停止時間によっては、研磨液供給用の管路に滞留する研磨液中の砥粒の凝集が進行し、その結果、大粒径の砥粒を含まない研磨液が研磨液循環装置（Ｌ４）から供給されるにも拘わらず、凝集の進行した砥粒を含む研磨液が研磨装置へ供給され、ウエハのスクラッチを発生させる虞がある。
【００４７】
そこで、本発明の製造装置においては、研磨装置（９）へ一層高品位の研磨液を供給するため、次の様な特定の研磨液供給装置（Ｌ５）が備えられていてもよい。すなわち、図１に示す様に、磨液循環装置（Ｌ４）の後段には、前述の研磨液循環装置（Ｌ４）におけるのと同様に研磨液中の大粒径の砥粒の発生を管理可能に構成され、かつ、研磨液循環装置（Ｌ４）によって循環される研磨液を研磨装置（９）へ供給する研磨液供給装置（Ｌ５）が備えられている。
【００４８】
具体的には、研磨液供給装置（Ｌ５）は、通常、各研磨装置（９）へ研磨液を供給するための複数の供給ラインによって構成され、各供給ラインは、研磨液供給用の管路（５７）及びそのバイパス管路（５７１）を備えている。そして、バイパス管路（５７１）は、流量調整弁（図示省略）やオリフィス等によって流量調整可能に構成され、斯かるバイパス管路（５７１）には、所定粒径以上の粒径の砥粒を検出し且つその数を計測する研磨液監視用のパーティクル検出器（８）が設けられる。また、各研磨液供給用の研磨液供給用の管路（５７）には、所定粒径以上の粒径の砥粒を捕捉する前述のフィルタ（６１）と同様のフィルタ（６２）がパーティクル検出器（８）の上流側に配置される。
【００４９】
パーティクル検出器（８）としては、前述のパーティクル検出器（７）と同様に、研磨液が通過するフローセルに一定波長の光を照射し、前記所定粒径以上の粒径の砥粒による透過光の減衰を検出する光遮断方式の検出器が使用される。そして、好ましくは、パーティクル検出器（８）のフローセルは、光の透過距離を０．１〜１００ｍｍに設定される。そして、パーティクル検出器（８）のフローセルは、バイパス管路（５７１）の流量調整によって一定の流速で研磨液が通過可能に構成される。
【００５０】
パーティクル検出器（８）の構造は、図２に示す前述のパーティクル検出器（７）の構造と同様である。そして、斯かるパーティクル検出器（８）には、所定粒径以上の粒径の砥粒による透過光の減衰を検出する際、研磨液中の所定粒径未満の砥粒による感度低下を補正する校正機能が備えられている。また、斯かる校正機能は、前述のパーティクル検出器（７）におけるのと同様に、パーティクル検出器（８）の演算処理手段に設けられる。
【００５１】
上記の様な研磨液供給装置（Ｌ５）においては、研磨液循環装置（Ｌ４）の管路（５６）に流れる研磨液を研磨装置（９）へ供給するにあたり、バイパス管路（５７１）に設けられたパーティクル検出器（８）は、研磨液が通過するフローセルに一定波長の光を照射し、所定粒径以上の粒径の砥粒、例えば粒径が３μｍ以上の大粒径の砥粒による透過光の減衰を検出することにより、研磨液中の大粒径の砥粒の数を計測する。
【００５２】
その際、前述のパーティクル検出器（７）の場合と同様に、流量調整可能なバイパス管路（５７１）にパーティクル検出器（８）が設けられた構造、および、バイパス管路（５７１）の流量調整によって一定の流速で研磨液が通過可能なフローセルの構造は、フローセルにおける研磨液の流量が制限されると共に、管路（５７）に生じた機器の脈動などによる影響がなく、しかも、フローセルに流れる研磨液中の所定粒径未満の砥粒の絶対数が低減されるため、フローセルの透過光を演算処理手段によって処理した場合、所定粒径未満の粒径の適正な砥粒による透過光の減衰と、所定粒径以上の粒径の砥粒による透過光の減衰とを分離でき、その結果、所定粒径以上の粒径の砥粒の数を正確に計測できる。
【００５３】
また、パーティクル検出器（８）に備えられた校正機能は、大粒径の砥粒による透過光の減衰を検出する際、研磨液中の所定粒径未満の砥粒による感度低下を補正し、大粒径の砥粒による透過光の減衰に対する検出感度を一層高めることが出来る。従って、研磨液供給装置（Ｌ５）が備えられた本発明の製造装置は、管路（５７）を通じて研磨装置（９）へ供給する研磨液において、所定粒径以上の大粒径の砥粒の発生およびその数をインラインで且つ連続的に、しかも、高精度に管理できる。
【００５４】
上記の様に管路（５７）においてインラインで研磨液を管理することにより、本発明の製造装置は、より一層高品位の研磨液を研磨装置（９）へ供給できる。例えば、本発明の製造装置においては、前述の態様と同様に、パーティクル検出器（８）によって検出された所定粒径以上の粒径の砥粒の一定流量当りの数が管理限界を越えた際、警報を発報させる機能が備えられていてもよい。発報機能は前述の制御装置（１０）に設けられる。そして、本発明の製造装置は、上記の様な発報と共に、研磨液供給装置（Ｌ５）による研磨液の供給を直ちに停止することも出来、その結果、大粒径の砥粒が含まれる研磨液が研磨装置（９）へ供給されるのを防止でき、ウエハのスクラッチ等、研磨装置（９）における加工不良を有効に防止できる。
【００５５】
更に、図示しないが、本発明の製造装置において、研磨液供給用の管路（５７）には、フィルタ（６２）と並列に供給路用の第２のフィルタが配置されており、パーティクル検出器（８）によって検出された所定粒径以上の粒径の砥粒の一定流量当りの数が管理限界を越えた際、第２のフィルタ側へ流路を切替可能になされていてもよい。すなわち、研磨液循環装置（Ｌ４）におけるのと同様に、所定粒径以上の砥粒を濾過するフィルタが管路（５７）に２系列並列に挿入されていることにより、フィルタ（６２）の機能が低下した場合、機能の低下していない第２のフィルタに直ちに切り替えることができ、研磨液の供給を停止することなく、高い品質の研磨液を研磨装置（９）へ供給できる。
【００５６】
なお、本発明において、管理すべき砥粒の粒径は、研磨条件に応じて適宜に設定し得る。また、上述の様なパーティクル検出器（７）及びパーティクル検出器（８）が設けられていることにより、砥粒に限らず、ポンプ、弁などの機器や管路で発生したパーティクル（異物）も管理できる。
【００５７】
【発明の効果】
本発明に係る研磨液の製造装置によれば、光遮断方式の特定のパーティクル検出器が研磨液循環用の管路のバイパス管路に設けられており、所定粒径以上の粒径の砥粒を確実に計測できるため、調製槽で調製されて研磨液循環装置の管路を循環する研磨液において、所定粒径以上の粒径の砥粒の発生およびその数をインラインで連続的に且つ高精度に管理でき、常に高品位の研磨液を研磨装置へ供給できる。更に、特定の校正機能がパーティクル検出器に備えられている場合には、所定粒径以上の粒径の砥粒の検出感度を一層高めることが出来る。
【００５８】
また、特定の研磨液供給装置が備えられた本発明の製造装置によれば、光遮断方式の特定のパーティクル検出器が研磨液供給用の管路のバイパス管路に設けられており、所定粒径以上の粒径の砥粒を確実に計測できるため、研磨液供給用の管路を通じて研磨装置へ供給する研磨液において、所定粒径以上の粒径の砥粒の発生およびその数をインラインで連続的に且つ高精度に管理でき、より一層高品位の研磨液を研磨装置へ供給できる。その結果、ウエハのスクラッチ等、研磨装置における加工不良を有効に防止できる。更に、特定の校正機能がパーティクル検出器に備えられている場合には、所定粒径以上の粒径の砥粒の検出感度を一層高めることが出来る。
【図面の簡単な説明】
【図１】本発明に係る研磨液の製造装置の概要を示す系統図
【図２】本発明に係る研磨液の製造装置に適用されるパーティクル検出器の原理を一部破断して示す側面図および平面図
【図３】パーティクル検出器のセンサーからの出力および変換された制御用のパルス信号の例を示すグラフ
【符号の説明】
２：調製槽
３：研磨液槽
５６：管路
５６１：バイパス管路
５７：管路
５７１：バイパス管路
６１：フィルタ
６２：フィルタ
７：パーティクル検出器
７４：フローセル
８：パーティクル検出器
９：研磨装置
Ｌ１：原液供給装置
Ｌ２：純水供給装置
Ｌ３：添加剤供給装置
Ｌ４：研磨液循環装置
Ｌ５：研磨液供給装置[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing liquid manufacturing apparatus, and more specifically, for example, a polishing liquid manufacturing apparatus for preparing a polishing liquid for chemical mechanical polishing used in polishing processing of a semiconductor device manufacturing process. The present invention relates to a polishing liquid manufacturing apparatus capable of continuously managing in-line the generation of abrasive grains having a particle diameter of a predetermined particle diameter or more.
[0002]
[Prior art]
Semiconductor devices are required to have higher integration, higher speed, and lower power consumption, and in the manufacturing process, the surface of metal wiring and interlayer insulating film formed on a wafer in an intermediate process is further flattened. Therefore, for example, a silica-based polishing liquid (CMP slurry) is used, and the surface of the wafer is subjected to chemical mechanical polishing. Recently, due to the problems of mass production of devices and composition management of the polishing liquid, the polishing liquid as described above is manufactured consistently in the polishing process. When producing a polishing liquid, it is necessary to strictly control the abrasive concentration in order to obtain an accurate polishing rate. In the polishing liquid, the aggregation of abrasive grains gradually proceeds, and the aggregated large abrasive grains may contribute to the generation of scratches on the wafer. Therefore, the size of the abrasive grains in the polishing liquid is controlled. Is becoming more important.
[0003]
In the production of the polishing liquid, the obtained polishing liquid is sampled and diluted with pure water, and then irradiated with light of a certain wavelength, and the intensity of the transmitted light and scattered light is measured to obtain large particles in the polishing liquid. The number of diameter abrasive grains is measured. The reason for managing the polishing liquid by sampling is as follows. That is, if the abrasive grains in the polishing liquid are to be directly measured on the production line, flow rate fluctuations due to pump pulsation or the like are affected, and therefore the number of abrasive grains cannot be measured accurately. The silica-based polishing liquid as described above has, for example, 10 silica particles having an average particle diameter of about 0.2 μm. ¹³ The number of abrasive grains having a very high concentration of particles / ml and a large particle size in question is small. Therefore, even if abrasive grains aggregated to a particle size of 3 μm or more are detected, it is difficult to detect attenuation due to large-diameter abrasive grains by direct measurement due to light attenuation by abrasive grains of appropriate grain size.
[0004]
[Problems to be solved by the invention]
By the way, since it takes a relatively long time to detect abrasive grains having a large particle size in the polishing liquid as described above, the polishing liquid used is actually different from the sampled polishing liquid. In other words, the polishing liquid used contains a larger amount of abrasive grains because the agglomeration further proceeds than when sampling, and as a result, in the polishing process, scratches occur unexpectedly on the wafer. There are things to do.
[0005]
The present invention has been made in view of the above circumstances, and an object thereof is a polishing liquid manufacturing apparatus for preparing a polishing liquid for chemical mechanical polishing used for polishing in a semiconductor device manufacturing process. Another object of the present invention is to provide an apparatus for producing a polishing liquid capable of managing the generation of abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter in the polishing liquid continuously in line with high accuracy.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, a polishing liquid manufacturing apparatus according to the present invention is a polishing liquid manufacturing apparatus that prepares a polishing liquid mainly composed of pure water and abrasive grains, and includes a supplied slurry stock solution and pure water. And a polishing tank for preparing a polishing liquid having a constant abrasive grain concentration, and a polishing liquid circulating device for circulating the prepared polishing liquid and maintaining a suspension state of the polishing liquid, and The liquid circulation device includes a polishing liquid circulation pipe and a bypass pipe whose flow rate can be adjusted. The bypass pipe detects abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter and measures the number thereof. A particle detector for monitoring the polishing liquid is provided, and the particle detector irradiates the flow cell through which the polishing liquid passes with light of a certain wavelength, and attenuates transmitted light by the abrasive grains having a particle diameter equal to or larger than the predetermined particle diameter. A light-blocking detector for detecting the flow sensor. Is characterized in that the polishing liquid at a constant flow rate by the flow rate adjustment of the bypass conduit is configured to be passed through.
[0007]
That is, in the manufacturing apparatus described above, after a polishing liquid having a constant abrasive grain concentration is mixed and prepared in the preparation tank, the suspended state is maintained while the polishing liquid is circulated by the polishing liquid circulation device. In addition, the particle detector for monitoring the polishing liquid provided in the bypass pipe of the pipe for circulating the polishing liquid irradiates the flow cell through which the polishing liquid passes with a light having a predetermined wavelength, and has a particle diameter equal to or larger than a predetermined particle diameter. Attenuation of transmitted light by abrasive grains is detected. At that time, the structure in which the particle detector is provided in the bypass pipe whose flow rate can be adjusted, and the structure of the flow cell in which the polishing liquid can pass at a constant flow rate by adjusting the flow rate in the bypass pipe are the flow rate of the polishing liquid in the flow cell. Is not affected by pulsation or the like generated in the pipeline for circulating the polishing liquid, and the absolute number of abrasive grains less than the predetermined particle diameter in the polishing liquid flowing in the flow cell is reduced. It is possible to separate the attenuation of transmitted light due to the abrasive grains having a particle diameter less than the diameter and the attenuation of transmitted light due to the abrasive grains having a particle diameter greater than or equal to a predetermined particle diameter.
[0008]
In the above manufacturing apparatus, the particle detector corrects a decrease in sensitivity due to abrasive grains having a particle size smaller than the predetermined particle size in the polishing liquid when detecting attenuation of transmitted light by abrasive particles having a particle size larger than a predetermined particle size. It is preferable that a calibration function is provided, and such a calibration function can increase the detection sensitivity with respect to attenuation of transmitted light caused by abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter.
[0009]
Further, in a more preferable aspect of the above manufacturing apparatus, since the high-quality polishing liquid is supplied by the polishing apparatus, the polishing liquid circulated by the polishing liquid circulation apparatus is provided to the polishing apparatus after the polishing liquid circulation apparatus. A polishing liquid supply device is provided, and the polishing liquid supply device includes a polishing liquid supply pipe and a bypass pipe whose flow rate can be adjusted. The bypass pipe has a predetermined particle size or more. A particle detector for monitoring a polishing liquid that detects abrasive grains having a particle diameter and measures the number thereof is provided. The particle detector irradiates a flow cell through which the polishing liquid passes with light of a predetermined wavelength, and A light blocking detector that detects the attenuation of transmitted light by abrasive grains having a diameter greater than or equal to the diameter, and the flow cell is configured to allow a polishing liquid to pass at a constant flow rate by adjusting the flow rate of the bypass pipe. That.
[0010]
That is, in the manufacturing apparatus described above, the polishing liquid circulated by the polishing liquid circulation apparatus is supplied to the polishing apparatus by the polishing liquid supply apparatus, and the above-mentioned is provided in the bypass conduit of the polishing liquid supply pipe. A similar particle detector for monitoring polishing liquid irradiates light having a certain wavelength to a flow cell through which the polishing liquid passes, and detects attenuation of transmitted light due to abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter. At that time, in the same manner as described above, a structure in which a particle detector is provided in a bypass conduit with an adjustable flow rate for supplying the polishing liquid, and a flow cell in which the polishing liquid can pass at a constant flow rate by adjusting the flow rate of the bypass pipe. In this structure, the flow rate of the polishing liquid in the flow cell is limited, there is no influence due to pulsation or the like generated in the polishing liquid supply conduit, and the abrasive particles having a particle diameter of less than a predetermined particle size in the polishing liquid flowing into the flow cell. Since the absolute number is reduced, it is possible to separate the attenuation of transmitted light due to abrasive grains having a particle size less than a predetermined particle size and the attenuation of transmitted light due to abrasive particles having a particle size greater than or equal to a predetermined particle size.
[0011]
Further, in the manufacturing apparatus of each aspect described above, the particle detector for monitoring the polishing liquid is less than the predetermined particle diameter in the polishing liquid when detecting attenuation of transmitted light due to the abrasive having a particle diameter equal to or larger than the predetermined particle diameter. It is preferable that a calibration function for correcting the sensitivity decrease due to the abrasive grains is provided, and such a calibration function can increase the detection sensitivity with respect to attenuation of transmitted light by the abrasive grains having a particle diameter equal to or larger than a predetermined grain diameter.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a polishing liquid production apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a system diagram showing an outline of a polishing liquid manufacturing apparatus according to the present invention. FIG. 2 is a partially broken view showing the principle of the particle detector applied to the polishing liquid manufacturing apparatus according to the present invention, where a part (a) is a side view and a part (b) is a plan view. It is. FIG. 3 is a graph showing an example of the output from the sensor of the particle detector and the converted pulse signal for control. In the system diagram of FIG. 1, valves and instrumentation devices are omitted. In the following description of the embodiments, a polishing liquid manufacturing apparatus is simply abbreviated as “manufacturing apparatus” as appropriate.
[0013]
The production apparatus of the present invention is a polishing liquid that mainly comprises pure water and abrasive grains, typically a silica-based polishing liquid (CMP slurry) for chemical mechanical polishing applied to semiconductor device polishing. This is a liquid manufacturing apparatus that can manufacture a high-quality polishing liquid on-site.
[0014]
In the case of the silica-based polishing liquid, the main components are fumed silica abrasive grains and pure water, and the grain size of the abrasive grains is usually less than 5 μm, preferably less than 3 μm, more preferably 0.1 to 2 μm. In addition, the content of abrasive grains is generally 10 to 30% by weight. Moreover, an additive may be added to the polishing liquid as necessary. The additive may be any component that can oxidize when polishing the surface of the metal wiring or removing the plug, and hydrogen peroxide is generally used. When polishing the silicon layer, an alkali such as potassium hydroxide is used as an additive. These acids or alkalis are added as an aqueous solution through an additive supply device (L3) described later.
[0015]
As shown in FIG. 1, the manufacturing apparatus of the present invention mixes a supplied slurry stock solution, that is, a slurry stock solution containing abrasive grains having a particle size of, for example, less than 3 μm and pure water, and a polishing solution having a constant abrasive grain concentration. And a polishing bath (L4) for circulating the prepared polishing liquid and maintaining the suspended state of the polishing liquid.
[0016]
Usually, the preparation tank (2) is supplied with a slurry stock solution having a constant concentration by a stock solution supply device (L1) and pure water by a pure water supply device (L2) (not shown). Further, a polishing liquid tank (3) for storing the polishing liquid prepared in the preparation tank (2) is provided in the subsequent stage of the preparation tank (2), and the polishing liquid circulation device (L4) The polishing liquid in the polishing liquid tank (3) is configured to be circulated. Further, the polishing liquid tank (3) is configured to be able to supply the additive as described above by the additive supply device (L3).
[0017]
The stock solution supply device (L1) is a device that pumps the slurry stock solution from the stock solution tank (1) to the preparation tank (2). Constant flow pump (not shown) and the like. The stock solution tank (1) is a storage tank for supplying the slurry stock solution to the preparation tank (2), and is constituted by a fixed container or a portable container having corrosion resistance.
[0018]
The stock solution tank (1) is provided with a pipe (not shown) that can be connected to a container for carrying a slurry stock solution carried from outside the system, through which the slurry stock solution is carried by an inert gas such as nitrogen. It is designed to be pumped from the container. The stock solution tank (1) is provided with an inert gas supply pipe (not shown) in order to prevent contact with air.
[0019]
The preparation tank (2) is a storage tank for adjusting the concentration of the polishing liquid to a predetermined concentration and storing the adjusted polishing liquid. For example, the preparation tank (2) is constituted by a container lined with a fluororesin in order to enhance corrosion resistance. The preparation tank (2) has a measuring device for measuring the weight of the slurry stock solution and pure water to be received, an optical method, a conductivity method, a capacitance method, etc. for measuring the amount of liquid. A total (not shown) is provided. In order to prevent contact with air, the preparation tank (2) is provided with an inert gas supply pipe (not shown).
[0020]
The pure water supply device (L2) is a device that supplies pure water for dilution to the preparation tank (2), and is prepared from a known pure water production apparatus that separates and purifies ultrapure water with an ion exchange resin or the like. ), And is usually adapted to pump pure water produced by the pure water production apparatus to the preparation tank (2) using a pump attached to the pure water production apparatus. ing.
[0021]
When the production amount is small, the polishing liquid prepared in the preparation tank (2) is immediately circulated by the polishing liquid circulation device (L4) and supplied to the polishing device (9) (plate apparatus). However, in order to stably supply the polishing liquid to the plurality of polishing apparatuses (9), the above-mentioned polishing liquid tank (3) is usually disposed downstream of the preparation tank (2). In the apparatus illustrated in FIG. 1, the polishing liquid mixed and prepared in the preparation tank (2) is transferred to the polishing liquid tank (3) by a pump (41) and a pipe line (53). In addition, the pipe line (54) in a figure is a return pipe line for monitoring the density | concentration of polishing liquid as needed, and returning polishing liquid to a preparation tank (2).
[0022]
The polishing liquid tank (4) is a storage tank for supplying the adjusted polishing liquid to an external polishing apparatus, and the acid or alkali additive as described above is supplied as an aqueous solution. Consists of a corrosion-resistant container lined with resin. In the polishing liquid tank (4), a liquid level gauge (not shown) capable of measuring points such as an optical type, a conductivity type, and a capacitance type is used to measure the amount of polishing liquid and the amount of additive added. Provided. In addition, in order to prevent contact with air, the polishing liquid tank (4) is provided with an inert gas supply pipe (not shown).
[0023]
The additive supply device (L3) for supplying the additive to the polishing liquid tank (4) is an apparatus for pumping the additive from the separately provided additive tank (not shown) to the polishing liquid tank (3). A conduit for removing the additive from the additive tank (not shown), a metering pump (not shown) for feeding a liquid such as a magnet pump whose flow rate is variable and controllable to a constant flow rate, and a polishing liquid tank ( 3) Consists of a pipe line (55) for supplying the additive to etc.
[0024]
Further, in the polishing liquid tank (4), a stirring mechanism for constantly stirring the polishing liquid by a jet is provided in order to prevent sedimentation and aggregation of the abrasive grain components. The stirring mechanism may be configured by a rotating device such as a stirring blade. For example, the stirring mechanism is a tip on the return side of the pipe (56) in the polishing liquid circulation device (L4) described later, that is, polishing liquid. It is comprised by the jet nozzle (not shown) attached to the pipe | tube front-end | tip inserted in the tank (3). Such a jet nozzle can generate a jet near the bottom of the polishing liquid tank (3) by the jetting energy of the polishing liquid as the driving pressurized fluid jetted from the return side tip of the pipe line (56).
[0025]
Although not shown, in the production apparatus of the present invention, a mixing tank is disposed between the preparation tank (2) and the polishing liquid tank (3) in order to increase the mixing efficiency of the polishing liquid and the additive. The polishing liquid supplied from 2) and the additive supplied from the additive supply device (L3) are mixed in advance in the mixing tank, and then the polishing liquid to which the additive has been added is stored in the polishing liquid tank (3). It may be made like.
[0026]
The polishing liquid circulator (L4) maintains a uniform suspension state of the prepared polishing liquid and reduces agglomeration of abrasive grains in the polishing liquid, and immediately supplies the polishing liquid to the polishing liquid supply apparatus (L5) described later. Is provided so that the polishing liquid in the polishing liquid tank (3) can be circulated. That is, the polishing liquid circulation device (L4) includes a polishing liquid circulation conduit (56) for taking out the polishing liquid from the polishing liquid tank (3) and returning the polishing liquid to the polishing liquid tank (3), and polishing. It comprises a pump (42) for feeding liquid.
[0027]
As described above, the polishing liquid is a liquid in which abrasive grains having a particle diameter of, for example, less than 3 μm are dispersed. Aggregation of the abrasive grains progresses over time, and large abrasive grains having a particle diameter of 3 μm or more. (Hereinafter, referred to as “large grain abrasive” as appropriate). Therefore, when the polishing liquid is used in the polishing apparatus (9), in order to prevent the wafer from being scratched by the large-diameter abrasive grains, a predetermined number of predetermined grains are provided in the polishing liquid circulation pipe (56). A circulation path filter (61) for capturing abrasive grains having a diameter larger than the diameter, specifically, for example, abrasive grains having a diameter of 3 μm or more is disposed upstream of a particle detector (7) described later.
[0028]
As such a filter (61), a normal fluid filter provided with a depth type filter medium made of polypropylene having a pore diameter of about 1.0 to 5.0 μm is used. The polishing liquid circulation device (L4) can supply the polishing liquid to a concentration measuring device (not shown) through a bypass pipe (not shown) in order to manage the additive concentration in the polishing liquid tank (3). Also good.
[0029]
Since the production apparatus of the present invention manages the generation and number of abrasive grains having a large particle size in the polishing liquid in the polishing liquid circulation device (L4), the polishing liquid circulation pipe of the polishing liquid circulation device (L4) (56) is provided with a bypass conduit (561) whose flow rate can be adjusted by a flow rate adjusting valve (not shown), an orifice or the like, and the bypass conduit (561) has the above-mentioned predetermined particle size. A particle detector for monitoring a polishing liquid that detects and measures the number of abrasive grains having a particle diameter equal to or larger than the diameter, that is, large abrasive grains larger than a preset particle diameter, for example, abrasive grains having a particle diameter of 3 μm or more. 7) is provided.
[0030]
As described above, when the average particle size of suitable abrasive grains in the silica-based polishing liquid is, for example, less than 3 μm, the particle size may be 3 μm or more due to the progress of aggregation, and in some cases, it may be several μm or more. The number of such large-diameter abrasive grains is extremely small compared to the number of abrasive grains having an appropriate particle diameter in the polishing liquid. For example, when the average grain size of appropriate abrasive grains in the polishing liquid is about 0.2 μm, the number is 10 ¹³ The number of large-diameter abrasive grains that cause scratches is about 10 to 1000 pieces / ml. Therefore, as the particle detector (7), a light blocking method for irradiating the flow cell (74) through which the polishing liquid passes with light of a certain wavelength and detecting attenuation of transmitted light due to abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter. Detectors are used.
[0031]
The basic structure of a light blocking detector is known, and such a detector has a structure that irradiates light (slurry) flowing through a transparent flow cell and detects the amount of transmitted light by a light receiving element. The size of the particles is measured by reducing the amount of light due to light absorption, reflection or scattering by the particles passing through the flow cell, and the number of particles is measured by the number of changes in the amount of light obtained as a pulse. Yes.
[0032]
Specifically, as shown in FIG. 2, the main part of the particle detector (7) is a tungsten lamp, a light emitting diode, a semiconductor laser, etc. that emits light of a certain wavelength by the power supplied by the power supply circuit (71). The light source (72), the condenser lens (73) that condenses the light emitted from the light source (72) into, for example, a flat belt-like light beam, and a cylindrical material having a rectangular cross section, for example, by a transparent material such as quartz glass The flow cell (74), the light receiving element (75) that detects the intensity of light transmitted through the light source (72) that has passed through the flow cell (74), the light receiving element (75) such as an optical array, and the output signal of the light receiving element (75) are amplified. It comprises an amplifier (76) and arithmetic processing means (arithmetic circuit including a storage / arithmetic element) for arithmetically processing the signal of the light receiving element.
[0033]
In general, in the measurement of abrasive grains having a large particle size in the polishing liquid, as described above, a very small number of abrasive grains in the polishing liquid having an abrasive concentration of, for example, 10 to 30% by weight must be detected. Therefore, depending on the setting of the lower limit of the particle size of the large abrasive grain to be detected, the influence (noise) due to light absorption, reflection or scattering by the appropriate abrasive grain is large, and the large abrasive grain is accurately Hard to detect. Furthermore, when the fluid is pulsated by a device such as a pump, the number of particles cannot be measured accurately.
[0034]
On the other hand, in the present invention, the particle detector (7) is provided in the bypass line (561) whose flow rate is limited by the bypass line (561), so that the polishing liquid circulation line (56) is provided. The influence of pulsation is prevented, and the influence (noise) caused by the abrasive grains having an appropriate grain size is reduced, and the small number of abrasive grains having a large grain diameter can be accurately detected. That is, the flow cell (74) is configured to allow the polishing liquid to pass at a constant flow rate by adjusting the flow rate of the bypass pipe (561). Usually, the flow rate of the polishing liquid in the flow cell (74) is set to 1 to 500 ml / min, and the flow rate is set to 0.1 to 1 m / sec. Further, in order to detect abrasive grains having a large particle size more accurately, the light transmission distance in the flow cell (74) is preferably set to 0.1 to 100 mm.
[0035]
Furthermore, in the production apparatus of the present invention, in order to detect the abrasive grains having a large particle size in the circulating polishing liquid with higher accuracy, the particle detector (7) has a particle having a predetermined particle diameter or larger. When detecting the attenuation of transmitted light due to the abrasive grains having a diameter, a calibration function is provided to correct a decrease in sensitivity due to abrasive grains having a grain size smaller than a predetermined grain size (abrasive grains having an appropriate grain size) in the polishing liquid. Such a calibration function is usually provided in the arithmetic processing means.
[0036]
That is, in the particle detector (7), as shown in FIG. 3 (a), the light receiving element (75) outputs the received light signal as a pulse signal, but the above arithmetic processing means is obtained. After the pulse signal is processed into a waveform as shown in FIG. 3B, a signal higher than the lower limit threshold voltage preset by the standard sample is counted. The above standard sample includes a certain amount (for example, 15% by weight) of abrasive grains having a predetermined particle diameter (for example, abrasive grains having a particle diameter of less than 3 μm) and the same particle diameter as that to be detected (for example, 3 μm). A polishing liquid added with polystyrene latex particles as standard particles is used.
[0037]
The production apparatus of the present invention includes a stock solution supply apparatus (L1), a preparation tank (2), a pure water supply apparatus (L2), a polishing liquid tank (3), an additive supply apparatus (L3), and a polishing liquid circulation apparatus (L4). ), A control device (10) for controlling the polishing liquid supply device (L5) to be described later and issuing an alarm to be described later based on the detection signal of the particle detector (7). Such a control device (10) includes an input device for digitally converting signals of each device, an arithmetic processing device such as a program controller or a computer including storage means, and an output device for analog conversion of a control signal from the arithmetic processing device. Mainly composed.
[0038]
Next, a method for producing a polishing liquid using the production apparatus of the present invention will be described. In the production apparatus of the present invention, first, a slurry stock solution having a constant abrasive grain concentration is metered from the stock solution tank (1) to the preparation tank (2), and pure water is supplied to the preparation tank (2) by the pure water supply device (L2). After a predetermined amount is metered in, the polishing liquid is mixed and prepared in the preparation tank (2). At that time, while circulating the polishing liquid in the preparation tank (2) through the pump (41) and the pipe (54), the slurry concentration is measured by the concentration measuring device attached to the pipe (54), and the measurement result Based on the above, by finely adjusting the supply amount of the slurry stock solution or pure water, the abrasive concentration (slurry concentration) of the polishing liquid is adjusted to, for example, 15% by weight.
[0039]
The polishing liquid prepared in the preparation tank (2) is supplied to the polishing liquid tank (3) through the pipe line (53). Next, the additive as described above is supplied to the polishing liquid supplied to the polishing liquid tank (3) from the additive supply device (L3) through the pipe line (55) as necessary. And an additive is stirred and mixed by said stirring mechanism provided in the polishing liquid tank (3), and a polishing liquid having a predetermined abrasive concentration and a predetermined additive concentration is prepared. Note that the concentration of the additive is such that a part of the polishing liquid flowing through the pipe line (56) of the polishing liquid circulation device (L4) is supplied to the concentration measuring device, and the additive supply device (L3) is based on the measurement result. It is adjusted by controlling the supply amount of the additive or the supply amount of the polishing liquid supplied from the pipe line (53).
[0040]
The polishing liquid having a predetermined composition finally prepared in the polishing liquid tank (3) is circulated by the polishing liquid circulation device (L4). That is, by using the pump (42) and the pipe line (56) of the polishing liquid circulation device (L4), the polishing liquid taken out from the polishing liquid tank (3) is returned to the polishing liquid tank (3) again, Maintain a uniform suspension of abrasive grains in the polishing liquid. Further, at that time, the filter (61) interposed in the pipe line (56) captures abrasive grains having a large particle diameter of a predetermined particle diameter or more in which the aggregation progresses in the circulating polishing liquid. Thereby, the polishing liquid that does not substantially contain large-diameter abrasive grains can be circulated through the pipe line (56).
[0041]
By the way, the above-mentioned large-diameter abrasive grains in the polishing liquid increase as the residence time in the polishing liquid tank (3) and the polishing liquid circulation device (L4) becomes longer, and also due to the function deterioration of the filter (61). To increase. In contrast, in the manufacturing apparatus of the present invention, a part of the polishing liquid in the pipe (56) is supplied to the bypass pipe (561), and the particle detector for monitoring the polishing liquid in the bypass pipe (561) is supplied. The polishing liquid is monitored by (7). That is, the particle detector (7) provided in the bypass line (561) irradiates the flow cell (74) through which the polishing liquid passes with light of a certain wavelength, and abrasive grains having a particle size equal to or larger than a predetermined particle size, for example, The number of abrasive grains having a large particle diameter in the polishing liquid is measured by detecting the attenuation of transmitted light by the abrasive grains having a large particle diameter of 3 μm or more.
[0042]
At this time, the particle detector (7) is provided in the bypass conduit (561) capable of adjusting the flow rate, and the structure of the flow cell (74) through which the polishing liquid can pass at a constant flow rate by adjusting the flow rate of the bypass conduit (561). Is limited by the flow rate of the polishing liquid in the flow cell (74), is not affected by the pulsation of equipment such as a pump generated in the pipe (56) for polishing liquid circulation, and flows into the flow cell (74). Since the absolute number of abrasive grains having a particle size less than the predetermined particle size in the polishing liquid is reduced, when the light transmitted through the flow cell (74) received by the light receiving element (75) is processed by the arithmetic processing means, the particles having the particle size less than the predetermined particle size are obtained. Attenuation of transmitted light by abrasive grains having an appropriate diameter (abrasive grains having a particle diameter of less than 3 μm, for example) and attenuation of transmitted light by abrasive grains having a particle diameter of a predetermined particle diameter or more (abrasive grains having a particle diameter of, for example, 3 μm or more) And can be separated As a result, the number of abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter can be accurately measured.
[0043]
In addition, the calibration function provided in the particle detector (7) corrects a decrease in sensitivity due to abrasive grains having a particle size less than a predetermined size in the polishing liquid when detecting the attenuation of transmitted light due to the abrasive particles having a large particle size. In addition, it is possible to further increase the detection sensitivity with respect to the attenuation of transmitted light due to the large-diameter abrasive grains. Therefore, in the manufacturing apparatus of the present invention, in the polishing liquid circulating through the pipe line (56) of the polishing liquid circulating apparatus (L4), the generation and the number of abrasive grains having a large particle diameter of a predetermined particle diameter or more are continuously inline. Moreover, it can be managed with high accuracy.
[0044]
In the production apparatus of the present invention, by managing the resulting polishing liquid in-line as described above, a high-quality polishing liquid can always be supplied to the polishing apparatus (9). For example, in the manufacturing apparatus of the present invention, a function for issuing an alarm when the number of abrasive grains having a particle diameter greater than or equal to a predetermined particle diameter detected by the particle detector (7) per control flow rate exceeds a control limit. May be provided. Such a control function of the number of abrasive grains and an alarm issuing function are usually provided in the control device (10). Further, the supply of the polishing liquid to the polishing apparatus (9) may be stopped along with the above notification. Furthermore, by managing the polishing liquid in-line, the filter medium of the filter can be replaced immediately when the function of the filter (61) is lowered, and the polishing liquid supplied to the polishing apparatus (9) can always be maintained in high quality.
[0045]
Although not shown, in the manufacturing apparatus of the present invention, the circulation line (56) is provided with a second circulation path filter in parallel with the filter (61), and the particle detector (7). The flow path may be switchable to the second filter side when the number of abrasive grains having a particle diameter of a predetermined particle diameter or more detected by (1) exceeds a control limit. That is, when the function of the filter (61) is reduced because the filter for filtering abrasive grains having a predetermined particle diameter or more is inserted into the pipe line (56) in two lines in parallel, the second function is not deteriorated. It is possible to immediately switch to this filter, and it is possible to always supply a high-quality polishing liquid to the polishing apparatus (9) without stopping the operation.
[0046]
Incidentally, the polishing liquid circulating apparatus (L4) as described above is usually provided with a plurality of pipes for supplying the polishing liquid to the polishing apparatus. The polishing liquid is supplied to the polishing apparatus by controlling the gate valve in the pipeline according to the operation. Therefore, depending on the stop time of the polishing apparatus, agglomeration of abrasive grains in the polishing liquid staying in the polishing liquid supply pipeline proceeds, and as a result, polishing liquid that does not contain large-diameter abrasive grains circulates in the polishing liquid. In spite of being supplied from the apparatus (L4), the polishing liquid containing the agglomerated abrasive grains is supplied to the polishing apparatus, which may cause scratching of the wafer.
[0047]
Therefore, in the production apparatus of the present invention, the following specific polishing liquid supply device (L5) may be provided in order to supply a higher quality polishing liquid to the polishing apparatus (9). That is, as shown in FIG. 1, in the subsequent stage of the polishing liquid circulation device (L4), it is possible to manage the generation of large-diameter abrasive grains in the polishing liquid as in the above-mentioned polishing liquid circulation device (L4). And a polishing liquid supply device (L5) for supplying the polishing liquid circulated by the polishing liquid circulation device (L4) to the polishing device (9).
[0048]
Specifically, the polishing liquid supply device (L5) is usually composed of a plurality of supply lines for supplying the polishing liquid to each polishing device (9), and each supply line is a conduit for supplying the polishing liquid. (57) and a bypass line (571) thereof. The bypass pipe (571) is configured so that the flow rate can be adjusted by a flow rate adjusting valve (not shown), an orifice, or the like. The bypass pipe (571) is provided with abrasive grains having a particle size equal to or larger than a predetermined particle size. A polishing liquid monitoring particle detector (8) for detecting and measuring the number of particles is provided. Further, in the polishing liquid supply pipe (57) for supplying each polishing liquid, a filter (62) similar to the above-described filter (61) for capturing abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter is used for particle detection. Placed upstream of the vessel (8).
[0049]
As the particle detector (8), similarly to the above-described particle detector (7), the flow cell through which the polishing liquid passes is irradiated with light of a certain wavelength, and the light transmitted by the abrasive particles having a particle diameter equal to or larger than the predetermined particle diameter. A light blocking detector that detects the attenuation of the light is used. Preferably, the flow cell of the particle detector (8) has a light transmission distance of 0.1 to 100 mm. The flow cell of the particle detector (8) is configured to allow the polishing liquid to pass at a constant flow rate by adjusting the flow rate of the bypass pipe line (571).
[0050]
The structure of the particle detector (8) is the same as that of the above-described particle detector (7) shown in FIG. The particle detector (8) corrects a decrease in sensitivity due to the abrasive grains having a particle diameter smaller than the predetermined particle size in the polishing liquid when detecting the attenuation of transmitted light by the abrasive grains having a particle diameter larger than or equal to the predetermined particle diameter. A calibration function is provided. Further, such a calibration function is provided in the arithmetic processing means of the particle detector (8) as in the above-described particle detector (7).
[0051]
In the polishing liquid supply apparatus (L5) as described above, the polishing liquid flowing in the pipe line (56) of the polishing liquid circulation apparatus (L4) is supplied to the polishing apparatus (9) and provided in the bypass pipe (571). The obtained particle detector (8) irradiates the flow cell through which the polishing liquid passes with light of a certain wavelength, and is made of abrasive grains having a particle diameter of a predetermined particle diameter or larger, for example, abrasive grains having a large particle diameter of 3 μm or larger. By detecting the attenuation of transmitted light, the number of large-diameter abrasive grains in the polishing liquid is measured.
[0052]
At that time, as in the case of the particle detector (7) described above, a structure in which the particle detector (8) is provided in the bypass conduit (571) capable of adjusting the flow rate, and the flow rate of the bypass conduit (571). The structure of the flow cell that allows the polishing liquid to pass at a constant flow rate by the adjustment limits the flow rate of the polishing liquid in the flow cell and is not affected by the pulsation of the equipment generated in the pipe line (57). Since the absolute number of abrasive grains having a particle size less than the predetermined particle size in the flowing polishing liquid is reduced, when the transmitted light of the flow cell is processed by the arithmetic processing means, Attenuation and attenuation of transmitted light due to abrasive grains having a particle diameter greater than or equal to a predetermined particle diameter can be separated, and as a result, the number of abrasive grains having a particle diameter greater than or equal to a predetermined particle diameter can be accurately measured.
[0053]
In addition, the calibration function provided in the particle detector (8) corrects a decrease in sensitivity due to abrasive grains having a particle size smaller than a predetermined particle size in the polishing liquid when detecting attenuation of transmitted light due to the abrasive particles having a large particle size. The detection sensitivity with respect to the attenuation of transmitted light by the large-diameter abrasive grains can be further increased. Therefore, the manufacturing apparatus of the present invention provided with the polishing liquid supply device (L5) is a polishing liquid to be supplied to the polishing apparatus (9) through the pipe line (57). The occurrence and the number thereof can be managed inline and continuously with high accuracy.
[0054]
By managing the polishing liquid in-line in the pipe line (57) as described above, the manufacturing apparatus of the present invention can supply a higher-quality polishing liquid to the polishing apparatus (9). For example, in the manufacturing apparatus of the present invention, when the number of abrasive grains having a particle diameter of a predetermined particle diameter or more detected by the particle detector (8) per control flow rate exceeds the control limit, as in the above-described embodiment. A function for issuing an alarm may be provided. The notification function is provided in the control device (10). And the manufacturing apparatus of this invention can also stop supply of the polishing liquid by polishing liquid supply apparatus (L5) immediately with the above reports, As a result, the grinding | polishing containing a large-diameter abrasive grain is included. It is possible to prevent the liquid from being supplied to the polishing apparatus (9), and it is possible to effectively prevent processing defects in the polishing apparatus (9) such as wafer scratches.
[0055]
Further, although not shown, in the manufacturing apparatus of the present invention, a second filter for supply path is arranged in parallel with the filter (62) in the pipe (57) for supplying polishing liquid, and the particle detector When the number of abrasive grains having a particle diameter equal to or larger than the predetermined particle diameter detected in (8) exceeds a control limit, the flow path may be switched to the second filter side. That is, as in the polishing liquid circulating device (L4), a filter for filtering abrasive grains having a predetermined particle diameter or more is inserted in the pipe line (57) in two lines in parallel, whereby the function of the filter (62). Can be immediately switched to the second filter whose function is not reduced, and high-quality polishing liquid can be supplied to the polishing apparatus (9) without stopping the supply of the polishing liquid.
[0056]
In the present invention, the grain size of the abrasive grains to be managed can be appropriately set according to the polishing conditions. In addition, since the particle detector (7) and the particle detector (8) as described above are provided, not only abrasive particles but also particles (foreign matter) generated in devices such as pumps and valves and pipes. Can manage.
[0057]
【The invention's effect】
According to the polishing liquid manufacturing apparatus of the present invention, the specific particle detector of the light blocking method is provided in the bypass pipe line of the polishing liquid circulation pipe, and the abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter. In the polishing liquid prepared in the preparation tank and circulating in the pipe of the polishing liquid circulation device, the generation and number of abrasive grains having a particle size of a predetermined particle size or more can be continuously and in-line. It can be managed with high accuracy and can always supply high-quality polishing liquid to the polishing equipment. Furthermore, when a specific calibration function is provided in the particle detector, it is possible to further increase the detection sensitivity of abrasive grains having a particle size greater than or equal to a predetermined particle size.
[0058]
Further, according to the manufacturing apparatus of the present invention provided with the specific polishing liquid supply device, the specific particle detector of the light blocking method is provided in the bypass pipe line of the polishing liquid supply pipe, Since it is possible to reliably measure abrasive grains with a particle size greater than or equal to the diameter, in the polishing liquid supplied to the polishing apparatus through the polishing liquid supply conduit, the generation and number of abrasive grains with a particle diameter larger than the predetermined particle diameter are in-line. It can be managed continuously and with high accuracy, and an even higher quality polishing liquid can be supplied to the polishing apparatus. As a result, processing defects in the polishing apparatus such as wafer scratching can be effectively prevented. Furthermore, when a specific calibration function is provided in the particle detector, it is possible to further increase the detection sensitivity of abrasive grains having a particle size greater than or equal to a predetermined particle size.
[Brief description of the drawings]
FIG. 1 is a system diagram showing an outline of an apparatus for producing a polishing liquid according to the present invention.
FIGS. 2A and 2B are a side view and a plan view, partially broken away, showing the principle of a particle detector applied to an apparatus for producing a polishing liquid according to the present invention.
FIG. 3 is a graph showing an example of an output from a sensor of a particle detector and a converted pulse signal for control.
[Explanation of symbols]
2: Preparation tank
3: Polishing bath
56: Pipe line
561: Bypass pipeline
57: Pipe line
571: Bypass pipeline
61: Filter
62: Filter
7: Particle detector
74: Flow cell
8: Particle detector
9: Polishing device
L1: Stock solution supply device
L2: Pure water supply device
L3: Additive supply device
L4: Polishing liquid circulation device
L5: Polishing liquid supply device

Claims

A polishing liquid production apparatus for preparing a polishing liquid mainly composed of pure water and abrasive grains, which is a preparation tank (2 for mixing a supplied slurry raw solution and pure water to prepare a polishing liquid having a constant abrasive grain concentration. ) And a polishing liquid circulation device (L4) that circulates the prepared polishing liquid and maintains the state of suspension of the polishing liquid, and the polishing liquid circulation device (L4) is a tube for polishing liquid circulation And a bypass pipe (561) whose flow rate can be adjusted. The bypass pipe (561) detects abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter and measures the number of the abrasive grains. Particle detector (7) is provided, and the particle detector (7) irradiates the flow cell (74) through which the polishing liquid passes with light of a certain wavelength, and is made of abrasive grains having a particle diameter equal to or larger than the predetermined particle diameter. It is a light blocking detector that detects the attenuation of transmitted light, and is a flow cell (7 ), The polishing liquid of the manufacturing apparatus, characterized in that the polishing liquid is configured to be passed at a constant flow rate by the flow rate adjustment of the bypass conduit (561).

The particle detector (7) has a calibration function for correcting a decrease in sensitivity due to abrasive grains having a particle diameter smaller than the predetermined particle size in the polishing liquid when detecting attenuation of transmitted light due to abrasive grains having a particle diameter larger than or equal to a predetermined particle diameter. The apparatus for producing a polishing liquid according to claim 1.

The polishing liquid tank (3) for storing the polishing liquid prepared in the preparation tank (2) is provided, and the polishing liquid circulation device (L4) is configured to circulate the polishing liquid in the polishing liquid tank (3). The manufacturing apparatus of the polishing liquid according to claim 1 or 2.

The apparatus for producing a polishing liquid according to claim 3, wherein the polishing liquid tank (3) is configured such that the additive can be supplied by the additive supply apparatus (L 3).

In the polishing liquid circulation pipe (56), a circulation path filter (61) for capturing abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter is disposed upstream of the particle detector (7). Item 5. A polishing liquid production apparatus according to any one of Items 1 to 4.

In the circulation pipe (56), a second filter for circulation is arranged in parallel with the filter (61), and abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter detected by the particle detector (7). The polishing liquid manufacturing apparatus according to claim 5, wherein when the number per fixed flow rate exceeds a control limit, the flow path can be switched to the second filter side.

A function for issuing an alarm when the number of abrasive grains having a particle diameter of a predetermined particle diameter or more detected by the particle detector (7) per control flow rate exceeds a control limit is provided. An apparatus for producing a polishing liquid according to any one of the above.

A polishing liquid supply device (L5) for supplying the polishing liquid circulated by the polishing liquid circulation device (L4) to the polishing device (9) is provided at the subsequent stage of the polishing liquid circulation device (L4), and the polishing liquid supply The apparatus (L5) includes a polishing liquid supply pipe (57) and a bypass pipe (571) whose flow rate can be adjusted. The bypass pipe (571) includes abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter. A particle detector (8) for monitoring the polishing liquid and for measuring the number of particles is provided, and the particle detector (8) irradiates the flow cell through which the polishing liquid passes with light of a predetermined wavelength, and A light-blocking detector that detects the attenuation of transmitted light due to abrasive grains having a diameter larger than the diameter, and the flow cell is configured such that the polishing liquid can pass at a constant flow rate by adjusting the flow rate of the bypass line (571). It is described in any one of Claims 1-7. Polishing liquid manufacturing apparatus.

The particle detector (8) has a calibration function for correcting a decrease in sensitivity due to abrasive grains having a particle diameter smaller than a predetermined particle size in the polishing liquid when detecting attenuation of transmitted light due to the abrasive grains having a particle diameter larger than or equal to a predetermined particle diameter. The apparatus for producing a polishing liquid according to claim 8.

In the polishing liquid supply pipe (57), a supply path filter (62) for capturing abrasive grains having a particle diameter equal to or larger than a predetermined particle diameter is disposed upstream of the particle detector (8). Item 10. The polishing liquid production apparatus according to Item 8 or 9.

In the pipeline (57) for supplying the polishing liquid, a second filter for the supply path is arranged in parallel with the filter (62), and the particle diameter is equal to or larger than the predetermined particle diameter detected by the particle detector (8). The apparatus for producing a polishing liquid according to claim 10, wherein the flow path can be switched to the second filter side when the number of abrasive grains per fixed flow rate exceeds a control limit.

A control device (10) is provided that issues an alarm when the number of abrasive grains having a particle diameter of a predetermined particle diameter or more detected by the particle detector (8) per control flow rate exceeds a control limit. Item 12. A polishing liquid production apparatus according to any one of Items 8 to 11.