JP3749422B2

JP3749422B2 - Concentration control method and concentration control device for each component in mixed fluid

Info

Publication number: JP3749422B2
Application number: JP2000088907A
Authority: JP
Inventors: 正明山村; 和男中島
Original assignee: Screen Holdings Co Ltd; Dainippon Screen Manufacturing Co Ltd
Current assignee: Screen Holdings Co Ltd; Dainippon Screen Manufacturing Co Ltd
Priority date: 2000-03-28
Filing date: 2000-03-28
Publication date: 2006-03-01
Anticipated expiration: 2020-03-28
Also published as: JP2001269633A

Description

【０００１】
【発明の属する技術分野】
この発明は、アンモニア水と過酸化水素水との混合溶液中のアンモニアおよび過酸化水素の各成分の濃度がそれぞれ適正範囲内となるように制御する混合流体中の各成分の濃度制御方法、ならびに、その方法を実施するために使用される濃度制御装置に関し、この濃度制御方法および濃度制御装置は、例えば、半導体ウエハ、液晶表示装置用ガラス基板、電子部品などの基板を、処理槽内に収容されたアンモニア水と過酸化水素水との混合溶液からなる処理液中に浸漬させて処理する基板処理などにおいて、処理槽内の混合溶液中のアンモニアおよび過酸化水素の各成分の濃度をそれぞれ適正に管理する場合などに用いられる。
【０００２】
【従来の技術】
例えば、半導体デバイスの製造プロセスにおいて、基板、例えばシリコンウエハの表面に付着したパーティクルや有機物といった不要物をウエハ表面から除去する場合には、アンモニア水と過酸化水素水と純水との混合溶液を用いてウエハを洗浄し、その洗浄後にウエハを純水で水洗して、ウエハ上に残存している薬液や分解生成物等の不要物をウエハ表面から除去するようにしている。このようなウエハの洗浄処理において、処理品質を高くかつ均一に維持するためには、混合溶液中のアンモニア成分および過酸化水素成分の各濃度をそれぞれ適正に管理する必要がある。
【０００３】
アンモニア水と過酸化水素水との混合溶液中のアンモニア成分および過酸化水素成分の各濃度を管理する方法としては、例えば特開平８−１５１４６号公報、実用新案登録公報第２５３３４６０号等に開示されているように、混合溶液中のアンモニア濃度を、赤外光の吸光度を測定することに検出するとともに、混合溶液中の過酸化水素濃度を紫外光の吸光度を測定することにより検出し、各成分の濃度変化に応じてアンモニア水もしくは過酸化水素水の高濃度原液または純水の供給量を調整することにより、混合溶液中のアンモニア成分および過酸化水素成分の各濃度がそれぞれ一定範囲となるように制御する方法が知られている。
【０００４】
このように、赤外光の吸光度を測定して溶液中のアンモニア濃度を検出し、また、紫外光の吸光度を測定して溶液中の過酸化水素濃度を検出する方法によると、アンモニア水あるいは過酸化水素水の単独水溶液であれば、その各濃度は、それぞれ赤外光あるいは紫外光の吸光度に比例する。したがって、水溶液の、赤外光あるいは紫外光の吸光度の変化を検出し、その吸光度が基準値から所定量以上変動していたときに、アンモニア水あるいは過酸化水素水の高濃度原液を水溶液に補充して、水溶液の吸光度が一定範囲となるように制御することが可能である。しかしながら、アンモニア水と過酸化水素水との混合溶液においてアンモニア成分および過酸化水素成分の各濃度がそれぞれ変化する場合には、測定される赤外光および紫外光の２種の吸光度は、それぞれアンモニア成分および過酸化水素成分の両方の濃度に依拠し、しかも、それぞれの成分単独の、各吸光度に対する寄与分の単純な線形和とはならない複雑な挙動を示す。
【０００５】
そこで、従来は、アンモニア水と過酸化水素水との混合溶液におけるアンモニア成分および過酸化水素成分の各濃度を種々に変化させて赤外光および紫外光の各吸光度をそれぞれ測定することにより、赤外光および紫外光の各吸光度と混合溶液中のアンモニア成分および過酸化水素成分の各濃度との関係を示す近似式を実験的に求めておき、測定された赤外光および紫外光の各吸光度を前記近似式にそれぞれ代入することにより、混合溶液中のアンモニア成分および過酸化水素成分の各濃度をそれぞれ算出し、その計算値に基づいて混合溶液中の各成分の濃度を制御するようにしていた。
【０００６】
また、予め、混合溶液中のアンモニア成分の濃度値と過酸化水素成分の濃度値との多数の組合せとそれぞれのときの赤外光および紫外光の各吸光度とを対応づける表を作成してマイクロコンピュータに記憶させておき、混合溶液の吸光度を測定するごとに、前記表を参照してアンモニア成分の濃度および過酸化水素成分の濃度をそれぞれ求める、といった方法も考えられる。さらに、混合溶液中のアンモニア成分の濃度の変化は赤外光の吸光度の変動に対して、また過酸化水素成分の濃度の変化は紫外光の吸光度の変動に対して、それぞれ寄与する程度が大きいことを利用し、赤外光の吸光度が変動したときは、アンモニア水の高濃度原液を混合溶液に補充し、紫外光の吸光度が変動したときは、過酸化水素水の高濃度原液を混合溶液に補充する、といった簡略化した濃度制御方法も考えられる。
【０００７】
【発明が解決しようとする課題】
しかしながら、混合溶液中の各成分の濃度と赤外光および紫外光の各吸光度との関係を表わす近似式を実験的に求めておき、その近似式を用いて混合溶液中の各成分の濃度を制御する方法は、各成分の濃度を算出するための計算が煩雑である上、広い濃度範囲にわたって精度良く濃度算出に適用することができる近似式を得ることは難しい、といった問題点がある。
【０００８】
また、混合溶液中の各成分の濃度値の組合せとそのときの赤外光および紫外光の各吸光度とを対応づける表を作成し記憶しておき、その表を参照して混合溶液中の各成分の濃度を制御する方法は、マイクロコンピュータの記憶容量の問題で、余り実用的でない。また、上記の簡略化した濃度制御方法は、一方の吸光度の変動に対し一方の薬液を混合溶液に補充すると、もう一方の吸光度にも必ず影響を及ぼすことになり、このため、それぞれの成分の濃度を共に目標値に収束させるのに多くの時間を要する、といった問題点がある。
【０００９】
この発明は、以上のような事情に鑑みてなされたものであり、アンモニア水と過酸化水素水との混合溶液中のアンモニアおよび過酸化水素の各成分の濃度を適正範囲に制御する場合において、各成分の濃度を算出するために煩雑な計算を行ったり各成分の濃度を求めるための表を予め作成し記憶しておいたりする、といったことを行わなくても、アンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度を測定しその各測定値に基づいた制御を行うだけで、アンモニアおよび過酸化水素の各成分の濃度を精度良く適正範囲に調整することができ、測定値が目標範囲から外れたとしても、測定値を目標範囲に速やかに戻すことができる濃度制御方法を提供すること、ならびに、その方法を好適に実施することができる濃度制御装置を提供することを目的とする。
【００１０】
【課題を解決するための手段】
請求項１に係る発明は、アンモニア水と過酸化水素水との混合溶液中のアンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度をそれぞれ測定し、その各測定値に基づいて混合溶液中のアンモニアおよび過酸化水素の各成分の濃度がそれぞれ適正範囲内となるように制御する混合流体中の各成分の濃度制御方法において、前記混合溶液中のアンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満となったとき、および、両方の測定値がそれぞれ所定の下限値未満となったときに、それぞれアンモニア成分を混合溶液に補充し、その後に必要に応じて過酸化水素成分を混合溶液に補充することを特徴とする。
【００１１】
請求項２に係る発明は、請求項１記載の濃度制御方法において、前記混合溶液の、赤外光および紫外光の各吸光度の測定値に応じて、混合溶液にアンモニア水の高濃度原液を補充しもしくはアンモニアガスを溶解させ、もしくは過酸化水素水の高濃度原液を補充し、または純水を追加し、混合溶液の、紫外光および赤外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満となったとき、および、両方の測定値がそれぞれ所定の下限値未満となったときに、それぞれアンモニア水の高濃度原液を混合溶液に補充しまたはアンモニアガスを混合溶液に溶解させ、その後に必要に応じて過酸化水素水の高濃度原液を混合溶液に補充しまたは純水を混合溶液に追加することを特徴とする。
【００１２】
請求項３に係る発明は、請求項２記載の濃度制御方法において、混合溶液の、紫外光の吸光度が所定の上限値を越えたとき、および、紫外光の吸光度が所定範囲内で赤外光の吸光度が所定の上限値を越えたときに、混合溶液にそれぞれ純水を追加し、混合溶液の、赤外光の吸光度が所定の上限値を越えかつ紫外光の吸光度が所定の下限値未満となったときに混合溶液に過酸化水素水の高濃度原液を補充することを特徴とする。
【００１３】
請求項４に係る発明は、請求項３記載の濃度制御方法において、アンモニア水と過酸化水素水との混合溶液が、洗浄槽内に収容され基板を浸漬させて基板表面を洗浄するために使用される洗浄液であることを特徴とする。
【００１４】
請求項５に係る発明は、アンモニア水と過酸化水素水との混合溶液中のアンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度をそれぞれ測定する吸光光度計と、アンモニアおよび過酸化水素の各成分を混合溶液にそれぞれ補充する成分補充手段と、前記吸光光度計による赤外光および紫外光の各吸光度の測定値に基づいて、混合溶液中のアンモニアおよび過酸化水素の各成分の濃度がそれぞれ適正範囲内となるように前記成分補充手段を制御する補充制御手段と、を備えた混合流体中の各成分の濃度制御装置において、前記混合溶液中のアンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満となったとき、および、両方の測定値がそれぞれ所定の下限値未満となったときに、それぞれアンモニア成分を混合溶液に補充し、その後に必要に応じて過酸化水素成分を混合溶液に補充するように、前記補充制御手段による前記成分補充手段の制御が行われるようにしたことを特徴とする。
【００１５】
請求項６に係る発明は、請求項５記載の濃度制御装置において、前記成分補充手段が、アンモニア水の高濃度原液を混合溶液に補充するアンモニア水供給部またはアンモニアガスを混合溶液に溶解させるアンモニアガス溶解部と、過酸化水素水の高濃度原液を混合溶液に補充する過酸化水素水供給部とであり、さらに純水を混合溶液に追加する純水供給部を設け、混合溶液の、紫外光および赤外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満となったとき、および、両方の測定値がそれぞれ所定の下限値未満となったときに、それぞれアンモニア水の高濃度原液を混合溶液に補充しまたはアンモニアガスを混合溶液に溶解させ、その後に必要に応じて過酸化水素水の高濃度原液を混合溶液に補充しまたは純水を混合溶液に追加するように、前記補充制御手段による前記アンモニア水供給部および過酸化水素水供給部ならびに純水供給部の制御が行われるようにしたことを特徴とする。
【００１６】
請求項７に係る発明は、請求項６記載の濃度制御装置において、混合溶液の、紫外光の吸光度が所定の上限値を越えたとき、および、紫外光の吸光度が所定範囲内で赤外光の吸光度が所定の上限値を越えたときに、混合溶液にそれぞれ純水を追加し、混合溶液の、赤外光の吸光度が所定の上限値を越えかつ紫外光の吸光度が所定の下限値未満となったときに混合溶液に過酸化水素水の高濃度原液を補充するように、前記補充制御手段による前記純水供給部および過酸化水素水供給部の制御が行われるようにしたことを特徴とする。
【００１７】
請求項８に係る発明は、請求項６または請求項７記載の濃度制御装置において、アンモニア水と過酸化水素水との混合溶液が、洗浄槽内に収容され基板を浸漬させて基板表面を洗浄するために使用される洗浄液であることを特徴とする。
【００１８】
請求項１に係る発明の濃度制御方法では、混合溶液の、赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満になると、あるいは、両方の測定値がそれぞれ所定の下限値未満になると、アンモニア成分が混合溶液に補充される。その後、必要に応じて、例えば、アンモニア成分の補充によってアンモニア成分の濃度に対応する赤外光の吸光度の測定値が所定の上限値を越えても、紫外光の吸光度の測定値が所定の下限値未満のままであるときは、過酸化水素成分を混合溶液に補充するなどして、最終的に両方の測定値がそれぞれの所定範囲内に収束するようにされる。
【００１９】
以上のように、この濃度制御方法では、混合溶液の、赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満となったとき、あるいは、両方の測定値がそれぞれ所定の下限値未満となったときに、まず、アンモニア成分が混合溶液に補充され、そのアンモニア成分の補充により、アンモニア成分の濃度に対応する赤外光の吸光度の測定値と共に過酸化水素成分の濃度に対応する紫外光の吸光度の測定値も変化する。したがって、アンモニア成分の補充だけで、両方の測定値がそれぞれの所定範囲内となる可能性も高く、また、アンモニア成分の補充によってアンモニア成分の濃度に対応する赤外光の吸光度の測定値が所定の上限値を越えても、紫外光の吸光度の測定値が所定の下限値未満のままであるときは、過酸化水素成分を混合溶液に補充すればよく、このため、速やかに両方の測定値をそれぞれの所定範囲内に収束させることができる。そして、この方法では、アンモニアおよび過酸化水素の各成分の濃度を算出するために煩雑な計算を行ったりアンモニアおよび過酸化水素の各成分の濃度を求めるための表を予め作成し記憶しておいたりする、といったことを行う必要が無く、混合溶液の、赤外光および紫外光の各吸光度を測定しその測定値に基づいた制御を行うだけで、アンモニアおよび過酸化水素の各成分の濃度を精度良く適正範囲に調整することが可能になる。また、この濃度制御方法では、アンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度を測定し、その測定値を濃度値に変換しなくても、測定値に基づいて直接的に制御を行うことが可能である。
【００２０】
請求項２に係る発明の濃度制御方法では、混合溶液の、赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満になると、あるいは、両方の測定値がそれぞれ所定の下限値未満になると、アンモニア水の高濃度原液が混合溶液に補充されまたはアンモニアガスが混合溶液に溶解される。その後、必要に応じて、例えば、アンモニア成分の補充によって赤外光の吸光度の測定値が所定の上限値を越えても、紫外光の吸光度の測定値が所定の下限値未満のままであるときは、過酸化水素水の高濃度原液が混合流体に補充され、また、紫外光の吸光度の測定値が所定範囲内となり赤外光の吸光度の測定値が所定の上限値を越えたりしたときは、純水を混合溶液に追加するなどして、最終的に両方の測定値がそれぞれの所定範囲内に収束するようにされる。
【００２１】
ここで、赤外光の吸光度の測定値が所定範囲内で紫外光の測定値が所定の下限値未満になったときにも、過酸化水素水を補充しないでアンモニア成分を補充するのは、アンモニア成分と過酸化水素成分とが共存している溶液中では、混合溶液にアンモニア成分を補充すると、アンモニア成分による紫外光領域での吸収が起こることによる。
【００２２】
図３は、アンモニア成分と過酸化水素成分とが共存するときの、混合溶液中のアンモニア濃度に対する紫外光の吸光度の変化を示すグラフである。データは、液温が６０℃であるときのものであり、吸光度は、波長２９０ｎｍの紫外線に対するものである。図中、直線Ｉは、過酸化水素成分が存在しないときのものであり、吸光度は０である。また、曲線IIは、４００ｍｌの過酸化水素水に対してアンモニア水の添加量を変えたときの吸光度の変化を示し、曲線IIIは、８００ｍｌの過酸化水素水に対してアンモニア水の添加量を変えたときの吸光度の変化を示す。図３から分かるように、溶液中に過酸化水素成分が共存すると、アンモニア濃度が高くなるのに従って紫外光の吸光度が上昇し、また、溶液中の過酸化水素濃度が高いほど、アンモニア濃度の上昇に伴う紫外光の吸光度の上昇の程度が大きくなる（アンモニア水の添加量が多くなるに従って曲線Ｉと曲線IIとの間の開きが大きくなる）。
【００２３】
したがって、混合溶液の、赤外光の吸光度の測定値が所定範囲内でも紫外光の測定値が所定の下限値未満になったときには、混合溶液にアンモニア水を補充しまたはアンモニアガスを溶解させるようにする。これにより、赤外光の吸光度の測定値と共に紫外光の吸光度の測定値も上昇して、紫外光の吸光度の測定値が所定範囲内に移行することになる。そして、紫外光の吸光度の測定値が所定範囲内に移行した時点で、赤外光の吸光度の測定値が所定の上限値を越えてしまったときは、混合溶液中に純水を追加することにより、最終的に両方の測定値がそれぞれの所定範囲内に収束するようにされる。
【００２４】
また、純度の高いアンモニア水と過酸化水素水との混合溶液では、主としてアンモニアが経時的な濃度低下を起こし、過酸化水素の濃度変化は少ない、といった特性があるが、この濃度制御方法では、測定値が所定の下限値未満になったときに、まずアンモニア成分を混合溶液に補充するので、この点でも有利である。
【００２５】
請求項３に係る発明の濃度制御方法では、混合溶液の、紫外光の吸光度が所定の上限値を越えたとき、および、紫外光の吸光度が所定範囲内で赤外光の吸光度が所定の上限値を越えたときに、混合溶液にそれぞれ純水が追加されることにより、混合溶液中の過酸化水素濃度が下がり、この結果、紫外光の吸光度が低下して所定範囲内に移行し、また、混合溶液中のアンモニア濃度が下がり、この結果、赤外光の吸光度が低下して所定範囲内に移行する。一方、混合溶液の、赤外光の吸光度が所定の上限値を越えかつ紫外光の吸光度が所定の下限値未満となったときに、混合溶液に過酸化水素水の高濃度原液が補充されることにより、混合溶液中の過酸化水素濃度が上がり、この結果、紫外光の吸光度が上昇して所定範囲内に移行し、同時に、過酸化水素水の補充によって混合溶液中のアンモニア濃度が相対的に下がり、この結果、赤外光の吸光度が低下して所定範囲内に移行する。
【００２６】
なお、上記したように、アンモニア成分と過酸化水素成分とが共存している溶液中では、混合溶液にアンモニア成分を補充すると、アンモニア成分による紫外光領域での吸収が起こる。このため、混合溶液の、紫外光の吸光度が所定の上限値を越えかつ赤外光の吸光度が所定の下限値未満となったときには、混合溶液にアンモニア水の高濃度原液を補充しまたはアンモニアガスを溶解させても、アンモニア成分の補充によって赤外光の吸光度と共に紫外光の吸光度も上昇することになる。したがって、この場合には、混合溶液に純水を追加して、紫外光の吸光度を所定範囲内とした後に、混合溶液にアンモニア水を補充しまたはアンモニアガスを溶解させる、といったことが行われる。
【００２７】
請求項４に係る発明の濃度制御方法は、アンモニア水と過酸化水素水との混合溶液を洗浄液として用いた基板の洗浄処理において、洗浄液中のアンモニア濃度および過酸化水素濃度をそれぞれ適正範囲に維持させるために使用される。
【００２８】
請求項５に係る発明の濃度制御装置を使用する場合においては、吸光光度計によって測定された赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満になると、あるいは、両方の測定値がそれぞれ所定の下限値未満になると、補充制御手段により成分補充手段が制御されて、成分補充手段によりアンモニア成分が混合溶液に補充される。その後、必要に応じて、例えば、アンモニア成分の補充によってアンモニア成分の濃度に対応する赤外光の吸光度の測定値が所定の上限値を越えても、紫外光の吸光度の測定値が所定の下限値未満のままであるときは、過酸化水素成分が混合溶液に補充されるなどして、最終的に両方の測定値がそれぞれの所定範囲内に収束するようにされる。
【００２９】
請求項６に係る発明の濃度制御装置では、吸光光度計によって測定された混合溶液の、赤外光および紫外光の各吸光度のうちの一方の測定値が所定範囲内でもう一方の測定値が所定の下限値未満になると、あるいは、両方の測定値がそれぞれ所定の下限値未満になると、アンモニア水供給部からアンモニア水の高濃度原液を混合溶液に補充しまたはアンモニアガス溶解部でアンモニアガスを混合溶液に溶解させるように制御される。その後、必要に応じて、例えば、アンモニア成分の補充によって赤外光の吸光度の測定値が所定の上限値を越えても、紫外光の吸光度の測定値が所定の下限値未満のままであるときは、過酸化水素水の高濃度原液を混合流体に補充し、また、紫外光の吸光度の測定値が所定範囲内となり赤外光の吸光度の測定値が所定の上限値を越えたりしたときは、純水供給部から純水を混合溶液に追加するなどして、最終的に両方の測定値がそれぞれの所定範囲内に収束するように制御される。
【００３０】
請求項７に係る発明の濃度制御装置では、吸光光度計によって測定された混合溶液の、紫外光の吸光度が所定の上限値を越えたとき、および、紫外光の吸光度が所定範囲内で赤外光の吸光度が所定の上限値を越えたときに、純水供給部から混合溶液にそれぞれ純水が追加されることにより、混合溶液中の過酸化水素濃度が下がり、この結果、紫外光の吸光度が低下して所定範囲内に移行し、また、混合溶液中のアンモニア濃度が下がり、この結果、赤外光の吸光度が低下して所定範囲内に移行する。一方、吸光光度計によって測定された混合溶液の、赤外光の吸光度が所定の上限値を越えかつ紫外光の吸光度が所定の下限値未満となったときに、過酸化水素水供給部から混合溶液に過酸化水素水の高濃度原液が補充されることにより、混合溶液中の過酸化水素濃度が上がり、この結果、紫外光の吸光度が上昇して所定範囲内に移行し、同時に、過酸化水素水の補充によって混合溶液中のアンモニア濃度が相対的に下がり、この結果、赤外光の吸光度が低下して所定範囲内に移行する。
【００３１】
請求項８に係る発明の濃度制御装置は、アンモニア水と過酸化水素水との混合溶液を洗浄液として用いた基板の洗浄処理装置において、洗浄槽内に収容される洗浄液中のアンモニア濃度および過酸化水素濃度をそれぞれ適正範囲に維持させるために使用される。
【００３２】
【発明の実施の形態】
以下、この発明の好適な実施形態について図１および図２を参照しながら説明する。
【００３３】
図１は、この発明に係る濃度制御方法を実施するために使用される濃度制御装置の構成の１例を示す模式図であり、この濃度制御装置を基板洗浄装置に用いた例を示している。この基板洗浄装置は、底部に液導入口１２を有し内部に洗浄液１４が収容される洗浄槽１０を備えている。そして、洗浄処理しようとする基板、例えばシリコンウエハは、ウエハホルダ（図示せず）に複数枚収納されて、洗浄槽１０内へ投入され洗浄液１４中に浸漬させられる。
【００３４】
洗浄槽１０には、溢流液受け部１８が付設されており、洗浄槽１０の上部から溢れ出た洗浄液１４が溢流液受け部１８内へ流入するようになっている。溢流液受け部１８内には、液循環用配管２０の一端が挿入されており、液循環用配管２０の他端は、洗浄槽１０の液導入口１２に連通して接続されている。液循環用配管２０には、循環ポンプ２２、ヒータ２４およびフィルタ２６が介挿されており、洗浄液１４は、洗浄槽１０、溢流液受け部１８および液循環用配管２０で構成された循環経路を循環させられる。また、液循環用配管２０には、温度検出器２８が介挿されており、温度検出器２８によって検出された温度信号がコントローラ３０へ送られ、その信号に基づいてコントローラ３０から温度制御信号がヒータ２４へ送られ、循環経路を循環する洗浄液１４の温度が所定温度に維持されるように制御される。なお、図示していないが、液循環用配管２０の途中には、排液管が分岐して設けられており、排液管に設けられた開閉弁を開くことにより、循環経路を循環している洗浄液の一部を必要により排出することができるようになっている。
【００３５】
洗浄液１４は、アンモニア水と過酸化水素水と純水とを混合して調製される。この洗浄液１４を調製しかつ洗浄液中のアンモニア成分および過酸化水素成分の各濃度がそれぞれ適正範囲内となるように各薬液を補充するために、アンモニア水の高濃度原液および過酸化水素水の高濃度原液がそれぞれ別々に貯留された薬液タンク３２、３４が配設されており、また、純水供給源３６が設けられている。各薬液タンク３２、３４には、アンモニア水供給管３８および過酸化水素水供給管４０がそれぞれ接続されており、それぞれの薬液の供給管３８、４０の先端が溢流液受け部１８内にそれぞれ挿入されている。また、純水供給源３６は、洗浄槽１０内に先端が挿入された純水供給管４２に接続されている。そして、アンモニア水供給管３８、過酸化水素水供給管４０および純水供給管４２には、それぞれ開閉制御弁４４、４６、４８が介挿されている。それぞれの開閉制御弁４４、４６、４８は、コントローラ３０に接続されている。
【００３６】
また、液循環用配管２０の途中には、洗浄液の吸光度（透過光強度）を測定するための成分検出部５０が設けられている。成分検出部５０は、赤外吸光度測定部５２と紫外吸光度測定部５４とから構成されている。各吸光度測定部５２、５４は、光源５６、６２、液循環用配管２０に介挿されて内部を洗浄液が流通する測定セル５８、６４、および光検出器６０、６６からそれぞれ構成されており、各光検出器６０、６６から出力される検出信号がそれぞれコントローラ３０へ送られるようになっている。赤外吸光度測定部５２の光源５６には、赤外線を放射する、例えばハロゲンランプが使用され、その光検出器６０には、赤外線領域の測定波長に対する分光感度を有する、例えばＰｂＳ、ＧａＡｓＰ等からなる半導体素子を用いたものが使用される。また、紫外吸光度測定部５４の光源６２には、紫外線を放射する、例えば重水素ランプやキセノンランプが使用され、その光検出器６６には、紫外線領域の測定波長に対する分光感度を有する、例えばＧａＰ等からなる半導体素子を用いたものや紫外用光電管が使用される。
【００３７】
次に、上記した構成の基板洗浄装置における洗浄液中の各成分濃度の制御方法の１例について説明する。
【００３８】
洗浄液中のアンモニア濃度および過酸化水素濃度がそれぞれ適正範囲内となるときの赤外光および紫外光のそれぞれの吸光度範囲を、実験などにより予め把握しておき、それらを目標吸光度範囲とし、赤外光および紫外光の各吸光度の上限値および下限値をそれぞれ設定する。そして、アンモニア濃度および過酸化水素濃度がそれぞれ適正範囲内となるように洗浄液を調製して、洗浄槽１０内に洗浄液１４を貯留し、循環経路を通して洗浄液１４を循環させ、洗浄槽１０内の洗浄液１４を所定温度に調整し保持する。この状態で、ウエハホルダに保持された複数枚のシリコンウエハを洗浄槽１０内の洗浄液１４中に浸漬させて洗浄し、洗浄処理が終了すると、洗浄液１４中からウエハを引き上げて図示しない水洗槽へ移送し、次の複数枚のウエハを洗浄槽１０内へ投入する。
【００３９】
上記のようなウエハの一連の処理を行っている期間中、成分検出部５０において、循環経路を通して循環し洗浄槽１０内へ導入される洗浄液の、赤外光および紫外光の各吸光度が赤外吸光度測定部５２および紫外吸光度測定部５４によりそれぞれ測定され、それぞれの検出信号がコントローラ３０へ送られる。表１は、赤外光および紫外光の各吸光度の測定値と制御動作との関係をまとめたものであり、この表を参照しながら、洗浄液の濃度管理操作について説明する。
【００４０】
【表１】

【００４１】
ウエハの洗浄処理を繰り返し行っているうちに、洗浄液中のアンモニア濃度および過酸化水素濃度が次第に低下していき、それに伴って赤外光および紫外光の各吸光度の測定値が低下し、赤外光および紫外光の各吸光度のうちいずれか一方の測定値でも下限値未満になったことが検出されると、まず、コントローラ３０からアンモニア水供給管３８に介挿された開閉制御弁４４へ制御信号が送られて、開閉制御弁４４が開かれ、循環経路を通して循環している洗浄液に薬液タンク３２からアンモニア水の高濃度原液が補充される（表１の▲６▼、▲８▼、▲９▼）。このアンモニア水の補充により、上述したように、洗浄液の、赤外光の吸光度と共に紫外光の吸光度が上昇することになる。そして、赤外光および紫外光の各吸光度の測定値が所定範囲内に収まると、コントローラ３０から開閉制御弁４４へ制御信号が送られて、開閉制御弁４４が閉じられ、洗浄液へのアンモニア水の補充が停止される（表１の▲５▼）。
【００４２】
一方、洗浄液へのアンモニア水の補充を続けた結果、赤外光の吸光度の測定値が上限値を越えても、紫外光の吸光度の測定値が下限値未満であるときには、コントローラ３０から開閉制御弁４４へ制御信号が送られて、開閉制御弁４４が閉じられ、アンモニア水の補充が停止されるとともに、コントローラ３０から過酸化水素水供給管４０に介挿された開閉制御弁４６へ制御信号が送られて、開閉制御弁４６が開かれ、洗浄液に薬液タンク３４から過酸化水素水の高濃度原液が補充される（表１の▲７▼）。この過酸化水素水の補充により、紫外光の吸光度が上昇し、一方、アンモニア濃度が相対的に下がって赤外光の吸光度が低下することになる。そして、赤外光および紫外光の各吸光度の測定値が所定範囲内に収まると、コントローラ３０から開閉制御弁４６へ制御信号が送られて、開閉制御弁４６が閉じられ、洗浄液への過酸化水素水の補充が停止させられる（表１の▲５▼）。
【００４３】
また、洗浄液へのアンモニア水の補充により、紫外光の吸光度の測定値が適正範囲内となり、一方、赤外光の吸光度の測定値が上限値を越えてしまったときは、コントローラ３０から開閉制御弁４４へ制御信号が送られて、開閉制御弁４４が閉じられ、アンモニア水の補充が停止されるとともに、コントローラ３０から純水供給管４２に介挿された開閉制御弁４８へ制御信号が送られて、開閉制御弁４８が開かれ、洗浄槽１０内の洗浄液１４に純水供給源３６から純水が追加される（表１の▲４▼）。この純水の追加により、アンモニア濃度が下がって赤外光の吸光度が低下することになる。そして、赤外光および紫外光の各吸光度の測定値が所定範囲内に収まると、コントローラ３０から開閉制御弁４８へ制御信号が送られて、開閉制御弁４８が閉じられ、洗浄液への純水の供給が停止させられる（表１の▲５▼）。
【００４４】
さらに、赤外光の吸光度の測定値が適正範囲で紫外光の吸光度の測定値が上限値を越えた状態になったときや、赤外光および紫外光の各吸光度の両方の測定値が共に上限値を越えた状態になったときにも、上記と同様の操作により、それぞれ洗浄液に純水が追加される（表１の▲１▼、▲２▼）。また、赤外光の吸光度の測定値が下限値未満となり紫外光の吸光度の測定値が上限値を越えた状態になったときに、洗浄液にアンモニア水を補充すると、赤外光の吸光度の測定値が上昇することになるが、アンモニア成分と過酸化水素成分との共存下でのアンモニア濃度の上昇によって紫外光の吸光度の測定値もさらに上昇することになる。このため、一時的にこのような状態になったときは、洗浄液に純水を追加し（表１の▲３▼）、いったん紫外光の吸光度の測定値を上限値以下に下げた後に、洗浄液にアンモニア水を補充するようにする（表１の▲６▼）。
【００４５】
以上のような各動作を繰り返すことにより、洗浄液の、赤外光および紫外光の各吸光度の測定値が共に目標吸光度範囲内に収束するように制御される。これによって、結果的に洗浄液中のアンモニア濃度および過酸化水素濃度が、それぞれ適正範囲内となるように調整される。図２に、上記した一連の制御動作を行わせるためのフローチャートの１例を示す。図２中、ＵＶは紫外光の吸光度の測定値を示し、ＩＲは赤外光の吸光度の測定値を示す。
【００４６】
以上説明したような濃度制御方法によると、洗浄液の、赤外光および紫外光の各吸光度をそれぞれ測定しその各測定値に基づいた制御を行うだけで、洗浄液中のアンモニア濃度および過酸化水素濃度がそれぞれ適正範囲内となるように精度度良く制御することができる。また、吸光度の測定値が目標範囲から外れたとしても、測定値を目標範囲に速やかに戻すことができ、すなわちアンモニア濃度および過酸化水素濃度をそれぞれ適正範囲に速やかに戻すことができるので、安定した洗浄処理が行われることになる。さらに、この濃度制御方法では、洗浄液の吸光度を測定し、その測定値を濃度値に変換することなく、測定値に基づいて直接的に制御が行われるので、制御機構が簡単になり、制御精度も向上することになる。また、純度の高いアンモニア水と過酸化水素水との混合溶液では、主としてアンモニアが経時的な濃度低下を起こし、過酸化水素の濃度変化は少ない、といった特性があるが、この濃度制御方法では、測定値が所定の下限値未満になったときに、まずアンモニア水を洗浄液に補充するので、この点での有利性もある。
【００４７】
なお、上記した実施形態では、循環経路を通して循環している洗浄液にアンモニア成分を補充するのに、薬液タンク３２からアンモニア水の高濃度原液を溢流受け部１８内へ供給するようにしているが、それに代えて、ガスボンベ等のアンモニアガス供給源からアンモニアガスを溢流受け部１８へ供給し、溢流受け部１８に貯留されている洗浄液中にアンモニアガスを吹き込んで、アンモニアガスを洗浄液に溶解させるような構成としてもよい。また、液循環用配管２０の途中の、例えば温度検出器２８の介挿位置とフィルタ２６の介挿位置との間に、内部に中空糸膜等を有するガス溶解器を介挿させ、アンモニアガス供給源からガス溶解器へアンモニアガスを供給して、液循環用配管２０からガス溶解器内に流入しガス溶解器内を通過する洗浄液にアンモニアガスを溶解させた後、ガス溶解器内から洗浄液を液循環用配管２０内へ流出させるようにしてもよい。
【００４８】
また、上記した実施形態では、成分検出部５０を赤外吸光度測定部５２と紫外吸光度測定部５４とから構成し、それぞれの吸光度測定部５２、５４を光源５６、６２、測定セル５８、６４および光検出器６０、６６で構成したが、成分検出部５０の構成は、これに限らない。例えば、赤外線および紫外線の両方の発光領域を有する単一の光源を用い、その光源からの光を分岐させて各測定セルにそれぞれ入射させるようにしてもよい。また、赤外線領域および紫外線領域の両方の測定波長に対する分光感度を有する受光素子を用いた単一の光検出器を使用し、赤外光の吸光度を測定するタイミングと紫外光の吸光度を測定するタイミングとを予めプログラム等で区別しておき、それぞれの測定セルを通過した光を光検出器に入射させて、赤外光および紫外光の各吸光度を交互に測定するようにしてもよい。
【００５０】
【発明の効果】
請求項１に係る発明の濃度制御方法によると、アンモニア水と過酸化水素水との混合溶液中のアンモニアおよび過酸化水素の各成分の濃度を適正範囲に制御する場合に、各成分の濃度を算出するために煩雑な計算を行ったり各成分の濃度を求めるための表を予め作成し記憶しておいたりする、といった必要が無くなり、アンモニアおよび過酸化水素の各成分の濃度に対応する赤外光および紫外光の各吸光度を測定しその各測定値に基づいた制御を行うだけで、アンモニアおよび過酸化水素の各成分の濃度を精度良く適正範囲に調整することができる。また、測定値が目標範囲から外れたとしても、測定値を目標範囲に速やかに戻すことができ、すなわちアンモニアおよび過酸化水素の各成分の濃度が適正範囲内となるように速やかに戻すことができる。さらに、制御機構が簡単になり、制御精度も向上する。
【００５１】
請求項２に係る発明の濃度制御方法によると、混合溶液の、赤外光および紫外光の各吸光度をそれぞれ測定しその各測定値に基づいた制御を行うだけで、混合溶液中のアンモニア成分および過酸化水素成分の各濃度をそれぞれ精度良く適正範囲に調整することができ、また、吸光度の測定値が目標範囲から外れたとしても、測定値を目標範囲に速やかに戻すことができ、すなわちアンモニア成分および過酸化水素成分の各濃度が適正範囲内となるように速やかに戻すことができる。また、純度の高いアンモニア水と過酸化水素水との混合溶液では、主としてアンモニアが経時的な濃度低下を起こし、過酸化水素の濃度変化は少ない、といった特性があるが、この濃度制御方法は、その特性にも合致したものである。
【００５２】
請求項３に係る発明の濃度制御方法では、混合溶液中のアンモニア濃度および過酸化水素濃度が速やかに適正範囲内に収束するように調整される。
【００５３】
請求項４に係る発明の濃度制御方法では、アンモニア水と過酸化水素水との混合溶液を洗浄液として用いた基板の洗浄処理を行う場合に、洗浄液中のアンモニア濃度および過酸化水素濃度をそれぞれ適正範囲に維持させて、洗浄処理品質を高くかつ均一に保つことができる。
【００５４】
請求項５に係る発明の濃度制御装置を使用すると、請求項１に係る発明の方法を好適に実施することができ、上記した効果が確実に得られる。
【００５５】
請求項６に係る発明の濃度制御装置を使用すると、請求項２に係る発明の方法を好適に実施することができ、上記した効果が確実に得られる。
【００５６】
請求項７に係る発明の濃度制御装置では、混合溶液中のアンモニア濃度および過酸化水素濃度が速やかに適正範囲内に収束するように調整することができる。
【００５７】
請求項８に係る発明の濃度制御装置では、アンモニア水と過酸化水素水との混合溶液を洗浄液として用いた基板の洗浄処理において、洗浄液中のアンモニア濃度および過酸化水素濃度をそれぞれ適正範囲に維持させて、洗浄処理品質を高くかつ均一に保つことができる。
【図面の簡単な説明】
【図１】この発明に係る濃度制御方法を実施するために使用される濃度制御装置の構成の１例を示す模式図であり、この濃度制御装置を基板洗浄装置に用いた例を示す。
【図２】図１に示した濃度制御装置を用いて行われる一連の制御動作を行わせるためのフローチャートの１例を示す図である。
【図３】アンモニア成分と過酸化水素成分とが共存するときの、混合溶液中のアンモニア濃度に対する紫外光の吸光度の変化を示すグラフである。
【符号の説明】
１０洗浄槽
１２洗浄槽の液導入口
１４洗浄液
１８溢流液受け部
２０液循環用配管
２２循環ポンプ
２４ヒータ
２６フィルタ
２８温度検出器
３０コントローラ
３２、３４薬液タンク
３６純水供給源
３８アンモニア水供給管
４０過酸化水素水供給管
４２純水供給管
４４、４６、４８開閉制御弁
５０成分検出部
５２赤外吸光度測定部
５４紫外吸光度測定部
５６、６２光源
５８、６４測定セル
６０、６６光検出器[0001]
BACKGROUND OF THE INVENTION
This invention Components of ammonia and hydrogen peroxide in a mixed solution of ammonia water and hydrogen peroxide solution The concentration control method and the concentration control apparatus are related to a concentration control method of each component in a mixed fluid that controls the concentration of each of the components to be within an appropriate range, and a concentration control device used to perform the method. For example, a substrate such as a semiconductor wafer, a glass substrate for a liquid crystal display device, or an electronic component is accommodated in a processing tank Ammonia water and hydrogen peroxide water In substrate processing where the substrate is immersed in a processing solution consisting of a mixed solution of Ammonia and hydrogen peroxide components This is used to properly manage the concentration of each.
[0002]
[Prior art]
For example, when removing unnecessary substances such as particles and organic substances adhering to the surface of a substrate, for example, a silicon wafer, from a wafer surface in a semiconductor device manufacturing process, a mixed solution of ammonia water, hydrogen peroxide water, and pure water is used. The wafer is washed by using the wafer, and after the washing, the wafer is washed with pure water to remove unnecessary substances such as chemicals and decomposition products remaining on the wafer from the wafer surface. In such wafer cleaning processing, in order to maintain high processing quality and uniformity, it is necessary to appropriately manage the concentrations of the ammonia component and the hydrogen peroxide component in the mixed solution.
[0003]
Methods for managing the concentrations of the ammonia component and the hydrogen peroxide component in the mixed solution of ammonia water and hydrogen peroxide solution are disclosed in, for example, Japanese Patent Application Laid-Open No. 8-15146, Utility Model Registration No. 2533460, and the like. As shown, the ammonia concentration in the mixed solution is detected by measuring the absorbance of infrared light, and the hydrogen peroxide concentration in the mixed solution is detected by measuring the absorbance of ultraviolet light. By adjusting the supply amount of high concentration stock solution or pure water of ammonia water or hydrogen peroxide water according to the concentration change of each so that each concentration of ammonia component and hydrogen peroxide component in the mixed solution will be in a certain range, respectively There is a known method of controlling.
[0004]
Thus, according to the method of measuring the absorbance of infrared light to detect the ammonia concentration in the solution, and measuring the absorbance of ultraviolet light to detect the hydrogen peroxide concentration in the solution, ammonia water or excess In the case of a single aqueous solution of hydrogen oxide water, each concentration is proportional to the absorbance of infrared light or ultraviolet light. Therefore, when a change in absorbance of infrared light or ultraviolet light in an aqueous solution is detected and the absorbance fluctuates by a predetermined amount or more from a reference value, a high concentration stock solution of ammonia water or hydrogen peroxide solution is replenished to the aqueous solution. Thus, the absorbance of the aqueous solution can be controlled to be within a certain range. However, when the concentrations of the ammonia component and the hydrogen peroxide component change in the mixed solution of ammonia water and hydrogen peroxide solution, respectively, the two types of absorbances of infrared light and ultraviolet light to be measured are ammonia. It relies on the concentration of both the component and the hydrogen peroxide component, yet exhibits complex behavior that is not a simple linear sum of each component's contribution to each absorbance.
[0005]
Therefore, conventionally, by measuring the absorbance of each of infrared light and ultraviolet light by changing the concentration of each of the ammonia component and the hydrogen peroxide component in a mixed solution of ammonia water and hydrogen peroxide solution, An approximate expression indicating the relationship between the external light and ultraviolet light absorbances and the concentrations of the ammonia and hydrogen peroxide components in the mixed solution was experimentally determined, and the measured infrared and ultraviolet light absorbances were determined. Is substituted for each of the approximate equations to calculate the respective concentrations of the ammonia component and the hydrogen peroxide component in the mixed solution, and the concentration of each component in the mixed solution is controlled based on the calculated value. It was.
[0006]
In addition, a table is created in advance by associating a number of combinations of the ammonia component concentration value and the hydrogen peroxide component concentration value in the mixed solution with the respective absorbances of infrared light and ultraviolet light at each time. A method is also conceivable in which the concentration of the ammonia component and the concentration of the hydrogen peroxide component are determined by referring to the above table each time the absorbance of the mixed solution is measured by storing in a computer. Furthermore, changes in the concentration of the ammonia component in the mixed solution contribute significantly to changes in the absorbance of infrared light, and changes in the concentration of the hydrogen peroxide component greatly contribute to variations in the absorbance of ultraviolet light. When the absorbance of infrared light fluctuates, a high concentration stock solution of ammonia water is replenished to the mixed solution, and when the absorbance of ultraviolet light fluctuates, the high concentration stock solution of hydrogen peroxide solution is mixed with the mixed solution. A simplified concentration control method is also conceivable, such as replenishment.
[0007]
[Problems to be solved by the invention]
However, an approximate expression representing the relationship between the concentration of each component in the mixed solution and the absorbance of each of infrared light and ultraviolet light is experimentally obtained, and the concentration of each component in the mixed solution is determined using the approximate expression. The control method has problems in that the calculation for calculating the concentration of each component is complicated and it is difficult to obtain an approximate expression that can be applied to the concentration calculation with accuracy over a wide concentration range.
[0008]
In addition, a table that associates the combination of the concentration values of each component in the mixed solution with the respective absorbances of the infrared light and ultraviolet light at that time is created and stored, and each table in the mixed solution is referenced with reference to the table. The method of controlling the concentration of the component is not practical because of the problem of the storage capacity of the microcomputer. In addition, in the above simplified concentration control method, when one chemical solution is replenished to the mixed solution with respect to the fluctuation of one absorbance, the other absorbance is necessarily affected. There is a problem that it takes a lot of time to converge the density to the target value.
[0009]
This invention has been made in view of the above circumstances, Components of ammonia and hydrogen peroxide in a mixed solution of ammonia water and hydrogen peroxide solution When controlling the concentration of each component within an appropriate range, a complicated calculation is performed to calculate the concentration of each component, or a table for obtaining the concentration of each component is created and stored in advance. Even without, Ammonia and hydrogen peroxide components Corresponding to the concentration of Absorbance of infrared light and ultraviolet light Just measure and control based on each measured value. Ammonia and hydrogen peroxide components The concentration control method can be adjusted to an appropriate range with high accuracy and the measured value can be quickly returned to the target range even if the measured value is out of the target range. It is an object of the present invention to provide a concentration control device that can be suitably implemented.
[0010]
[Means for Solving the Problems]
The invention according to claim 1 Components of ammonia and hydrogen peroxide in a mixed solution of ammonia water and hydrogen peroxide solution Corresponding to the concentration of Absorbance of infrared light and ultraviolet light Based on each measured value Each component of ammonia and hydrogen peroxide in the mixed solution In the method for controlling the concentration of each component in the fluid mixture, the concentration of each of which is controlled to be within the appropriate range, Each absorbance of infrared light and ultraviolet light corresponding to the concentration of each component of ammonia and hydrogen peroxide in the mixed solution When one of the measured values is within the predetermined range and the other measured value is less than the predetermined lower limit, and when both measured values are less than the predetermined lower limit, Ammonia component mixed solution To refill and then as needed Hydrogen peroxide component mixed solution It is characterized by replenishing.
[0011]
The invention according to claim 2 is the concentration control method according to claim 1, The mixed solution Absorbance of infrared light and ultraviolet light of Depending on the measured value, replenish the mixed solution with high concentration stock solution of ammonia water or dissolve ammonia gas, or replenish with high concentration stock solution of hydrogen peroxide solution, or add pure water, When one measured value of each absorbance of light and infrared light is within a predetermined range and the other measured value is less than a predetermined lower limit value, and both measured values are less than a predetermined lower limit value, respectively. Each time, the high concentration stock solution of ammonia water is replenished to the mixed solution or the ammonia gas is dissolved in the mixed solution, and then the high concentration stock solution of hydrogen peroxide solution is replenished to the mixed solution as necessary. It is characterized by adding water to the mixed solution.
[0012]
The invention according to claim 3 is the concentration control method according to claim 2, wherein the ultraviolet light absorbance of the mixed solution exceeds a predetermined upper limit, and the ultraviolet light absorbance falls within a predetermined range. When the absorbance of the liquid exceeds the predetermined upper limit value, pure water is added to each of the mixed solutions, the absorbance of the mixed solution exceeds the predetermined upper limit value, and the absorbance of the ultraviolet light is less than the predetermined lower limit value. Then, the mixed solution is supplemented with a high concentration stock solution of hydrogen peroxide.
[0013]
The invention according to claim 4 is the concentration control method according to claim 3, wherein the mixed solution of ammonia water and hydrogen peroxide solution is accommodated in the cleaning tank and used for immersing the substrate to clean the substrate surface. It is characterized by being a cleaning liquid.
[0014]
The invention according to claim 5 Infrared and ultraviolet absorbances corresponding to the concentrations of ammonia and hydrogen peroxide components in a mixed solution of aqueous ammonia and hydrogen peroxide Measure each Absorptiometer When, Mixed solution of each component of ammonia and hydrogen peroxide Component replenishing means for replenishing each, Absorptiometer by For each absorbance of infrared light and ultraviolet light Based on the measured value Each component of ammonia and hydrogen peroxide in the mixed solution A concentration control device for each component in the mixed fluid, comprising: replenishment control means for controlling the component replenishment means so that the concentration of each component is within an appropriate range; Each absorbance of infrared light and ultraviolet light corresponding to the concentration of each component of ammonia and hydrogen peroxide in the mixed solution When one of the measured values is within the predetermined range and the other measured value is less than the predetermined lower limit, and when both measured values are less than the predetermined lower limit, Ammonia component mixed solution To refill and then as needed Hydrogen peroxide component mixed solution The component replenishing means is controlled by the replenishing control means so as to be replenished.
[0015]
The invention according to claim 6 is the concentration control apparatus according to claim 5. ,in front The component replenishment means replenishes the mixed solution with the ammonia water supply unit that replenishes the mixed solution with high concentration stock solution of ammonia water or the ammonia gas dissolving portion that dissolves ammonia gas in the mixed solution, and the high concentration stock solution of hydrogen peroxide solution. A pure water supply unit for adding pure water to the mixed solution, and one of the measured values of the absorbance of the ultraviolet light and infrared light of the mixed solution is within a predetermined range. When the other measured value is less than the predetermined lower limit value and when both measured values are less than the predetermined lower limit value, respectively, a high concentration stock solution of ammonia water is replenished to the mixed solution. Alternatively, ammonia gas is dissolved in the mixed solution, and then, if necessary, the high concentration stock solution of hydrogen peroxide solution is replenished to the mixed solution or pure water is added to the mixed solution. Wherein the control of the ammonia water supply and the hydrogen-peroxide-solution supply unit and the pure water supply unit has to be performed.
[0016]
The invention according to claim 7 is the concentration control apparatus according to claim 6, wherein the ultraviolet light absorbance of the mixed solution exceeds a predetermined upper limit, and the ultraviolet light absorbance falls within a predetermined range. When the absorbance of the liquid exceeds the predetermined upper limit, pure water is added to the mixed solution. The infrared absorbance of the mixed solution exceeds the predetermined upper limit and the absorbance of the ultraviolet light is less than the predetermined lower limit. The pure water supply unit and the hydrogen peroxide solution supply unit are controlled by the replenishment control means so that the mixed solution is supplemented with a high concentration stock solution of hydrogen peroxide solution. And
[0017]
The invention according to claim 8 is the concentration control apparatus according to claim 6 or 7, wherein a mixed solution of ammonia water and hydrogen peroxide solution is housed in a cleaning tank and the substrate is immersed to clean the substrate surface. It is characterized by being a cleaning liquid used for this purpose.
[0018]
In the concentration control method of the invention according to claim 1, Absorbance of infrared light and ultraviolet light of mixed solution When one of the measured values is within the predetermined range and the other measured value is less than the predetermined lower limit value, or when both measured values are less than the predetermined lower limit value, Ammonia component mixed solution To be replenished. Then, if necessary, for example Ammonia component By replenishing Ammonia component Corresponding to the concentration of Absorbance of infrared light Even if the measured value exceeds the specified upper limit, Absorbance of ultraviolet light If the measured value remains below the predetermined lower limit, Hydrogen peroxide component mixed solution Finally, both measured values are converged within respective predetermined ranges.
[0019]
As described above, in this density control method, Absorbance of infrared light and ultraviolet light of mixed solution When one of the measured values is within the predetermined range and the other measured value is less than the predetermined lower limit value, or when both measured values are respectively less than the predetermined lower limit value, Ammonia component mixed solution Replenished to that Ammonia component By replenishing Absorbance of infrared light corresponding to the concentration of ammonia component Together with measured values of Absorbance of ultraviolet light corresponding to the concentration of hydrogen peroxide component The measured value also changes. Therefore, Ammonia component It is highly likely that both measurements will be within their respective ranges simply by replenishing Ammonia component By replenishing Ammonia component Corresponding to the concentration of Absorbance of infrared light Even if the measured value exceeds the specified upper limit, Absorbance of ultraviolet light If the measured value remains below the predetermined lower limit, Hydrogen peroxide component mixed solution Therefore, both measured values can be quickly converged within the respective predetermined ranges. And in this way, Ammonia and hydrogen peroxide components Do complicated calculations to calculate the concentration of Ammonia and hydrogen peroxide components There is no need to create and store a table for determining the concentration of Absorbance of infrared light and ultraviolet light of mixed solution Just measure and control based on the measured value. Ammonia and hydrogen peroxide components It becomes possible to adjust the density of the water to an appropriate range with high accuracy. In this density control method, Ammonia and hydrogen peroxide components Corresponding to the concentration of Absorbance of infrared light and ultraviolet light It is possible to directly control based on the measured value without measuring the measured value and converting the measured value into a concentration value.
[0020]
In the concentration control method of the invention according to claim 2, when one measured value of each of the absorbances of infrared light and ultraviolet light of the mixed solution is within a predetermined range and the other measured value is less than a predetermined lower limit value. Alternatively, when both measured values are less than a predetermined lower limit value, a high concentration stock solution of ammonia water is replenished to the mixed solution or ammonia gas is dissolved in the mixed solution. Thereafter, if necessary, for example, when the measured value of the absorbance of the infrared light exceeds the predetermined upper limit value by supplementing the ammonia component, the measured value of the absorbance of the ultraviolet light remains below the predetermined lower limit value. When the high concentration stock solution of hydrogen peroxide solution is replenished to the mixed fluid, and the measured value of the absorbance of ultraviolet light is within the predetermined range and the measured value of the absorbance of infrared light exceeds the predetermined upper limit value, By adding pure water to the mixed solution, finally, both measured values are converged within respective predetermined ranges.
[0021]
Here, even when the measured value of the absorbance of the infrared light is within the predetermined range and the measured value of the ultraviolet light is less than the predetermined lower limit value, the ammonia component is replenished without replenishing the hydrogen peroxide solution. In a solution in which an ammonia component and a hydrogen peroxide component coexist, when the ammonia component is supplemented to the mixed solution, absorption in the ultraviolet region by the ammonia component occurs.
[0022]
FIG. 3 is a graph showing changes in the absorbance of ultraviolet light with respect to the ammonia concentration in the mixed solution when the ammonia component and the hydrogen peroxide component coexist. The data is for a liquid temperature of 60 ° C., and the absorbance is for ultraviolet light with a wavelength of 290 nm. In the figure, the straight line I is obtained when no hydrogen peroxide component is present, and the absorbance is zero. Curve II shows the change in absorbance when the amount of ammonia water added is changed with respect to 400 ml of hydrogen peroxide water, and curve III shows the amount of ammonia water added with respect to 800 ml of hydrogen peroxide water. The change in absorbance when changed is shown. As can be seen from FIG. 3, when the hydrogen peroxide component coexists in the solution, the absorbance of the ultraviolet light increases as the ammonia concentration increases, and the ammonia concentration increases as the hydrogen peroxide concentration in the solution increases. The degree of increase in the absorbance of ultraviolet light accompanying the increase is increased (the difference between curve I and curve II increases as the amount of ammonia water added increases).
[0023]
Therefore, when the measured value of the absorbance of the infrared light of the mixed solution is within the predetermined range, if the measured value of the ultraviolet light is less than the predetermined lower limit value, the mixed solution is replenished with ammonia water or the ammonia gas is dissolved. To. As a result, the measurement value of the absorbance of ultraviolet light rises together with the measurement value of the absorbance of infrared light, and the measurement value of the absorbance of ultraviolet light shifts within a predetermined range. Then, when the measured value of the absorbance of ultraviolet light has moved within the predetermined range, if the measured value of the absorbance of infrared light exceeds the predetermined upper limit, add pure water to the mixed solution. As a result, both measured values are finally converged within their predetermined ranges.
[0024]
In addition, in a mixed solution of high-purity ammonia water and hydrogen peroxide solution, ammonia mainly has a characteristic that the concentration of ammonia decreases with time and the concentration change of hydrogen peroxide is small. In this concentration control method, When the measured value becomes less than the predetermined lower limit value, the ammonia component is first replenished to the mixed solution, which is also advantageous in this respect.
[0025]
In the concentration control method of the invention according to claim 3, when the ultraviolet light absorbance of the mixed solution exceeds a predetermined upper limit, and the ultraviolet light absorbance is within a predetermined range, the infrared light absorbance is a predetermined upper limit. When the value is exceeded, the addition of pure water to the mixed solution decreases the concentration of hydrogen peroxide in the mixed solution. As a result, the absorbance of the ultraviolet light decreases and shifts to a predetermined range. The ammonia concentration in the mixed solution decreases, and as a result, the absorbance of infrared light decreases and shifts to a predetermined range. On the other hand, when the absorbance of infrared light of the mixed solution exceeds a predetermined upper limit value and the absorbance of ultraviolet light becomes less than the predetermined lower limit value, the mixed solution is replenished with a high concentration stock solution of hydrogen peroxide. As a result, the concentration of hydrogen peroxide in the mixed solution increases, and as a result, the absorbance of ultraviolet light increases and shifts within a predetermined range. As a result, the absorbance of infrared light decreases and shifts to a predetermined range.
[0026]
As described above, in a solution in which an ammonia component and a hydrogen peroxide component coexist, when the ammonia component is supplemented to the mixed solution, absorption in the ultraviolet region by the ammonia component occurs. Therefore, when the ultraviolet light absorbance of the mixed solution exceeds the predetermined upper limit value and the infrared light absorbance is less than the predetermined lower limit value, the mixed solution is supplemented with a high concentration stock solution of ammonia water or ammonia gas. Even if dissolved, the absorbance of ultraviolet light increases with the absorption of infrared light by replenishing the ammonia component. Therefore, in this case, after adding pure water to the mixed solution to make the ultraviolet light absorbance within a predetermined range, the mixed solution is supplemented with ammonia water or the ammonia gas is dissolved.
[0027]
The concentration control method of the invention according to claim 4 maintains the ammonia concentration and the hydrogen peroxide concentration in the cleaning solution within appropriate ranges in the substrate cleaning process using a mixed solution of ammonia water and hydrogen peroxide solution as the cleaning solution. Used to make.
[0028]
In the case of using the concentration control device of the invention according to claim 5, Absorptiometer Measured by Absorbance of infrared light and ultraviolet light When one of the measured values is within the predetermined range and the other measured value is less than the predetermined lower limit value, or when both measured values are less than the predetermined lower limit value, the component replenishing means is Controlled and by component replenishment means Ammonia component mixed solution To be replenished. Then, if necessary, for example Ammonia component By replenishing Ammonia component Corresponding to the concentration of Absorbance of infrared light Even if the measured value exceeds the specified upper limit, Absorbance of ultraviolet light If the measured value remains below the predetermined lower limit, Hydrogen peroxide component mixed solution In the end, both measured values are converged within respective predetermined ranges.
[0029]
In the concentration control apparatus of the invention according to claim 6, one measurement value of each of the absorbances of infrared light and ultraviolet light of the mixed solution measured by the absorptiometer is within a predetermined range, and the other measurement value is When the measured value is less than the predetermined lower limit value, or when both measured values are less than the predetermined lower limit value, respectively, a high concentration stock solution of ammonia water is replenished to the mixed solution from the ammonia water supply unit or ammonia gas is supplied at the ammonia gas dissolving unit. It is controlled to dissolve in the mixed solution. Thereafter, if necessary, for example, when the measured value of the absorbance of the infrared light exceeds the predetermined upper limit value by supplementing the ammonia component, the measured value of the absorbance of the ultraviolet light remains below the predetermined lower limit value. When a high concentration stock solution of hydrogen peroxide solution is replenished to the mixed fluid, or when the measured value of the absorbance of ultraviolet light is within the predetermined range and the measured value of the absorbance of infrared light exceeds the predetermined upper limit, Then, by adding pure water from the pure water supply unit to the mixed solution, finally, both measured values are controlled so as to converge within respective predetermined ranges.
[0030]
In the concentration control apparatus of the invention according to claim 7, when the ultraviolet light absorbance of the mixed solution measured by the absorptiometer exceeds a predetermined upper limit, and the ultraviolet light absorbance is within a predetermined range When the light absorbance exceeds a predetermined upper limit, pure water is added to the mixed solution from the pure water supply unit to reduce the concentration of hydrogen peroxide in the mixed solution. As a result, the absorbance of ultraviolet light Decreases and shifts to a predetermined range, and the ammonia concentration in the mixed solution decreases. As a result, the absorbance of infrared light decreases and shifts to a predetermined range. On the other hand, when the absorbance of infrared light of the mixed solution measured by the absorptiometer exceeds a predetermined upper limit value and the absorbance of ultraviolet light becomes less than the predetermined lower limit value, it is mixed from the hydrogen peroxide solution supply unit. By replenishing the solution with a high-concentration stock solution of hydrogen peroxide, the concentration of hydrogen peroxide in the mixed solution increases. As a result, the absorbance of ultraviolet light rises and shifts to a predetermined range, and at the same time, peroxidation occurs. By replenishing the hydrogen water, the ammonia concentration in the mixed solution is relatively lowered, and as a result, the absorbance of infrared light is lowered and moves within a predetermined range.
[0031]
The concentration control apparatus according to an eighth aspect of the present invention is a substrate cleaning processing apparatus using a mixed solution of ammonia water and hydrogen peroxide solution as a cleaning liquid, and the ammonia concentration and peroxidation in the cleaning liquid stored in the cleaning tank. Used to maintain the hydrogen concentration within an appropriate range.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of the present invention will be described below with reference to FIGS.
[0033]
FIG. 1 is a schematic diagram showing an example of the configuration of a concentration control apparatus used for carrying out the concentration control method according to the present invention, and shows an example in which this concentration control apparatus is used in a substrate cleaning apparatus. . The substrate cleaning apparatus includes a cleaning tank 10 having a liquid inlet 12 at the bottom and containing a cleaning liquid 14 therein. A plurality of substrates to be cleaned, such as silicon wafers, are stored in a wafer holder (not shown), put into the cleaning tank 10 and immersed in the cleaning liquid 14.
[0034]
The cleaning tank 10 is provided with an overflow liquid receiving part 18 so that the cleaning liquid 14 overflowing from the upper part of the cleaning tank 10 flows into the overflow liquid receiving part 18. One end of the liquid circulation pipe 20 is inserted into the overflow liquid receiving portion 18, and the other end of the liquid circulation pipe 20 is connected to and connected to the liquid inlet 12 of the cleaning tank 10. A circulation pump 22, a heater 24, and a filter 26 are inserted in the liquid circulation pipe 20, and the cleaning liquid 14 is a circulation path constituted by the cleaning tank 10, the overflow liquid receiving portion 18, and the liquid circulation pipe 20. Can be circulated. Further, a temperature detector 28 is inserted in the liquid circulation pipe 20, and a temperature signal detected by the temperature detector 28 is sent to the controller 30, and a temperature control signal is sent from the controller 30 based on the signal. Control is performed so that the temperature of the cleaning liquid 14 that is sent to the heater 24 and circulates in the circulation path is maintained at a predetermined temperature. Although not shown in the figure, a drainage pipe is branched in the middle of the liquid circulation pipe 20, and the circulation path is circulated by opening an on-off valve provided in the drainage pipe. A part of the cleaning liquid can be discharged if necessary.
[0035]
The cleaning liquid 14 is prepared by mixing ammonia water, hydrogen peroxide water, and pure water. In order to prepare this cleaning solution 14 and replenish each chemical solution so that the respective concentrations of the ammonia component and the hydrogen peroxide component in the cleaning solution are within appropriate ranges,

Chemical tanks

32 and 34 in which the concentrated concentrates are stored separately are provided, and a pure water supply source 36 is provided. An ammonia water supply pipe 38 and a hydrogen peroxide water supply pipe 40 are connected to the

chemical liquid tanks

32 and 34, respectively, and the tips of the chemical

liquid supply pipes

38 and 40 are respectively in the overflow liquid receiving portion 18. Has been inserted. The pure water supply source 36 is connected to a pure water supply pipe 42 whose tip is inserted into the cleaning tank 10. Opening /

closing control valves

44, 46, and 48 are inserted in the ammonia water supply pipe 38, the hydrogen peroxide water supply pipe 40, and the pure water supply pipe 42, respectively. Each open /

close control valve

44, 46, 48 is connected to the controller 30.
[0036]
In addition, a component detection unit 50 for measuring the absorbance (transmitted light intensity) of the cleaning liquid is provided in the middle of the liquid circulation pipe 20. The component detection unit 50 includes an infrared absorbance measurement unit 52 and an ultraviolet absorbance measurement unit 54. Each of the

absorbance measuring units

52 and 54 includes

light sources

56 and 62,

measurement cells

58 and 64 that are inserted in the liquid circulation pipe 20 and in which the cleaning liquid flows, and

photodetectors

60 and 66, respectively. Detection signals output from the

photodetectors

60 and 66 are sent to the controller 30, respectively. The light source 56 of the infrared absorbance measurement unit 52 uses, for example, a halogen lamp that emits infrared rays, and the photodetector 60 is made of, for example, PbS, GaAsP or the like having spectral sensitivity to the measurement wavelength in the infrared region. Those using semiconductor elements are used. Further, the light source 62 of the ultraviolet absorbance measurement unit 54 uses, for example, a deuterium lamp or a xenon lamp that emits ultraviolet rays, and the photodetector 66 has a spectral sensitivity with respect to a measurement wavelength in the ultraviolet region, for example, GaP. For example, an ultraviolet phototube or a semiconductor device using a semiconductor element made of the like is used.
[0037]
Next, an example of a method for controlling the concentration of each component in the cleaning liquid in the substrate cleaning apparatus having the above configuration will be described.
[0038]
Preliminarily grasp the absorbance ranges of infrared light and ultraviolet light when the ammonia concentration and hydrogen peroxide concentration in the cleaning solution are within the appropriate ranges by experimentation, etc., and set them as the target absorbance range. An upper limit value and a lower limit value for each absorbance of light and ultraviolet light are set. Then, the cleaning liquid is prepared so that the ammonia concentration and the hydrogen peroxide concentration are within appropriate ranges, the cleaning liquid 14 is stored in the cleaning tank 10, and the cleaning liquid 14 is circulated through the circulation path. 14 is adjusted to a predetermined temperature and held. In this state, a plurality of silicon wafers held by the wafer holder are immersed in the cleaning liquid 14 in the cleaning tank 10 for cleaning, and when the cleaning process is completed, the wafer is lifted from the cleaning liquid 14 and transferred to a water cleaning tank (not shown). Then, the next plurality of wafers are put into the cleaning tank 10.
[0039]
During the series of processing of the wafer as described above, in the component detection unit 50, the respective absorbances of the infrared light and the ultraviolet light of the cleaning liquid circulating through the circulation path and introduced into the cleaning tank 10 are infrared. Measurement is performed by the absorbance measurement unit 52 and the ultraviolet absorbance measurement unit 54, and respective detection signals are sent to the controller 30. Table 1 summarizes the relationship between the measured values of the respective absorbances of infrared light and ultraviolet light and the control operation, and the cleaning liquid concentration management operation will be described with reference to this table.
[0040]
[Table 1]

[0041]
As the wafer cleaning process is repeated, the ammonia concentration and hydrogen peroxide concentration in the cleaning solution gradually decrease, and the measured values of each absorbance of infrared light and ultraviolet light decrease accordingly. When it is detected that either one of the absorbance values of light and ultraviolet light is less than the lower limit value, the controller 30 first controls the open / close control valve 44 inserted in the ammonia water supply pipe 38. A signal is sent, the open / close control valve 44 is opened, and the high concentration stock solution of ammonia water is replenished from the chemical tank 32 to the cleaning liquid circulating through the circulation path ((6), (8), 9 ▼). By replenishing this ammonia water, as described above, the absorbance of the ultraviolet light as well as the absorbance of the infrared light of the cleaning liquid increases. When the measured values of the respective absorbances of infrared light and ultraviolet light fall within a predetermined range, a control signal is sent from the controller 30 to the open / close control valve 44, the open / close control valve 44 is closed, and ammonia water is supplied to the cleaning liquid. Is stopped ((5) in Table 1).
[0042]
On the other hand, as a result of continuing the replenishment of ammonia water to the cleaning liquid, when the measured value of the absorbance of ultraviolet light is less than the lower limit value even if the measured value of the absorbance of infrared light exceeds the upper limit value, the controller 30 controls the opening / closing. A control signal is sent to the valve 44, the open / close control valve 44 is closed, replenishment of ammonia water is stopped, and a control signal is sent from the controller 30 to the open / close control valve 46 inserted in the hydrogen peroxide solution supply pipe 40. Is opened, the open / close control valve 46 is opened, and the high concentration stock solution of hydrogen peroxide solution is replenished from the chemical liquid tank 34 to the cleaning liquid ((7) in Table 1). By replenishing the hydrogen peroxide solution, the absorbance of ultraviolet light is increased, while the ammonia concentration is relatively lowered and the absorbance of infrared light is decreased. When the measured values of the respective absorbances of infrared light and ultraviolet light fall within a predetermined range, a control signal is sent from the controller 30 to the open / close control valve 46, the open / close control valve 46 is closed, and overoxidation into the cleaning liquid is performed. The hydrogen water supply is stopped ((5) in Table 1).
[0043]
In addition, when the measured value of the absorbance of ultraviolet light is within the appropriate range due to the replenishment of the ammonia water to the cleaning liquid, on the other hand, when the measured value of the absorbance of infrared light exceeds the upper limit value, the controller 30 controls the opening / closing. A control signal is sent to the valve 44, the open / close control valve 44 is closed, replenishment of ammonia water is stopped, and a control signal is sent from the controller 30 to the open / close control valve 48 inserted in the pure water supply pipe 42. Then, the open / close control valve 48 is opened, and pure water is added from the pure water supply source 36 to the cleaning liquid 14 in the cleaning tank 10 ((4) in Table 1). By adding this pure water, the ammonia concentration is lowered and the absorbance of infrared light is lowered. When the measured values of the respective absorbances of infrared light and ultraviolet light fall within a predetermined range, a control signal is sent from the controller 30 to the open / close control valve 48, the open / close control valve 48 is closed, and pure water to the cleaning liquid is supplied. Is stopped ((5) in Table 1).
[0044]
Furthermore, when the measured value of the absorbance of infrared light is in the appropriate range and the measured value of the absorbance of ultraviolet light exceeds the upper limit, or both the measured values of both the absorbance of infrared light and ultraviolet light are both Even when the upper limit is exceeded, pure water is added to the cleaning liquid by the same operation as above ((1) and (2) in Table 1). In addition, when the measured value of the absorbance of infrared light is less than the lower limit and the measured value of the absorbance of ultraviolet light exceeds the upper limit, if the cleaning solution is supplemented with aqueous ammonia, the absorbance of the infrared light is measured. Although the value will increase, the measurement value of the absorbance of ultraviolet light will further increase due to the increase of the ammonia concentration in the presence of the ammonia component and the hydrogen peroxide component. For this reason, when such a state is temporarily reached, pure water is added to the cleaning liquid ((3) in Table 1), and once the measured value of the absorbance of ultraviolet light is lowered below the upper limit value, the cleaning liquid Ammonia water is replenished to (6 in Table 1).
[0045]
By repeating each operation as described above, control is performed so that the measured values of the absorbance of each of the infrared light and the ultraviolet light of the cleaning liquid converge within the target absorbance range. As a result, the ammonia concentration and the hydrogen peroxide concentration in the cleaning liquid are adjusted so as to be within appropriate ranges. FIG. 2 shows an example of a flowchart for performing the above-described series of control operations. In FIG. 2, UV indicates a measured value of absorbance of ultraviolet light, and IR indicates a measured value of absorbance of infrared light.
[0046]
According to the concentration control method as described above, the ammonia concentration and the hydrogen peroxide concentration in the cleaning solution can be obtained by simply measuring the respective absorbances of the cleaning solution for infrared light and ultraviolet light and performing control based on the measured values. Can be controlled with high accuracy so that each is within the appropriate range. In addition, even if the absorbance measurement value is out of the target range, the measurement value can be quickly returned to the target range, that is, the ammonia concentration and the hydrogen peroxide concentration can be promptly returned to the appropriate ranges. The cleaning process is performed. Further, in this concentration control method, the absorbance of the cleaning liquid is measured, and the control value is directly controlled based on the measured value without converting the measured value into a concentration value. Will also improve. In addition, in a mixed solution of high-purity ammonia water and hydrogen peroxide solution, ammonia mainly has a characteristic that the concentration of ammonia decreases with time and the concentration change of hydrogen peroxide is small. In this concentration control method, When the measured value becomes less than the predetermined lower limit value, ammonia water is first replenished to the cleaning liquid, which is advantageous in this respect.
[0047]
In the embodiment described above, a high concentration stock solution of ammonia water is supplied from the chemical liquid tank 32 into the overflow receiving part 18 in order to supplement the cleaning liquid circulating through the circulation path with the ammonia component. Instead, ammonia gas is supplied to the overflow receiver 18 from an ammonia gas supply source such as a gas cylinder, and the ammonia gas is blown into the cleaning liquid stored in the overflow receiver 18 to dissolve the ammonia gas in the cleaning liquid. It is good also as a structure to make it do. In addition, a gas dissolver having a hollow fiber membrane or the like is inserted between the insertion position of the temperature detector 28 and the insertion position of the filter 26, for example, in the middle of the liquid circulation pipe 20, and ammonia gas. After supplying ammonia gas from the supply source to the gas dissolver, the ammonia gas is dissolved in the cleaning liquid flowing into the gas dissolver from the liquid circulation pipe 20 and passing through the gas dissolver, and then the cleaning liquid is discharged from the gas dissolver. May be allowed to flow into the liquid circulation pipe 20.
[0048]
In the above-described embodiment, the component detection unit 50 includes the infrared absorbance measurement unit 52 and the ultraviolet absorbance measurement unit 54, and the respective

absorbance measurement units

52 and 54 include the

light sources

56 and 62, the

measurement cells

58 and 64, and Although it comprised with the

photodetectors

60 and 66, the structure of the component detection part 50 is not restricted to this. For example, a single light source having both infrared and ultraviolet emission regions may be used, and the light from the light source may be branched and incident on each measurement cell. In addition, using a single photodetector with a light receiving element that has spectral sensitivity for both infrared and ultraviolet measurement wavelengths, the timing for measuring the absorbance of infrared light and the timing of measuring the absorbance of ultraviolet light May be distinguished in advance by a program or the like, and light having passed through each measurement cell may be incident on a photodetector to alternately measure the absorbances of infrared light and ultraviolet light.
[0050]
【The invention's effect】
According to the concentration control method of the invention according to claim 1, Components of ammonia and hydrogen peroxide in a mixed solution of ammonia water and hydrogen peroxide solution When controlling the concentration of each component to an appropriate range, there is no need to perform complicated calculations to calculate the concentration of each component or to create and store a table for determining the concentration of each component in advance. , Ammonia and hydrogen peroxide components Corresponding to the concentration of Absorbance of infrared light and ultraviolet light Just measure and control based on each measured value. Ammonia and hydrogen peroxide components Can be accurately adjusted to an appropriate range. In addition, even if the measured value is out of the target range, the measured value can be quickly returned to the target range, that is, Ammonia and hydrogen peroxide components Can be promptly returned so that the concentration of is within an appropriate range. Furthermore, the control mechanism is simplified and the control accuracy is improved.
[0051]
According to the concentration control method of the invention according to claim 2, the ammonia component in the mixed solution can be obtained by simply measuring the respective absorbances of the infrared light and ultraviolet light of the mixed solution and performing control based on the measured values. Each concentration of the hydrogen peroxide component can be accurately adjusted to the appropriate range, and even if the absorbance measurement value deviates from the target range, the measurement value can be quickly returned to the target range, that is, ammonia. The concentration of each of the components and the hydrogen peroxide component can be quickly returned so as to be within the appropriate range. Moreover, in a mixed solution of high-purity ammonia water and hydrogen peroxide solution, ammonia mainly has a characteristic that the concentration decreases with time and the concentration change of hydrogen peroxide is small. It matches the characteristics.
[0052]
In the concentration control method according to the third aspect of the present invention, the ammonia concentration and the hydrogen peroxide concentration in the mixed solution are adjusted so as to quickly converge within an appropriate range.
[0053]
In the concentration control method of the invention according to claim 4, when the substrate is cleaned using a mixed solution of ammonia water and hydrogen peroxide solution as the cleaning solution, the ammonia concentration and the hydrogen peroxide concentration in the cleaning solution are respectively appropriate. The cleaning process quality can be kept high and uniform by maintaining the range.
[0054]
When the concentration control apparatus of the invention according to claim 5 is used, the method of the invention according to claim 1 can be suitably implemented, and the above-described effects can be obtained with certainty.
[0055]
When the concentration control apparatus of the invention according to claim 6 is used, the method of the invention of claim 2 can be suitably implemented, and the above-described effects can be obtained with certainty.
[0056]
In the concentration control apparatus according to the seventh aspect of the present invention, the ammonia concentration and the hydrogen peroxide concentration in the mixed solution can be adjusted so as to quickly converge within an appropriate range.
[0057]
In the concentration controller of the invention according to claim 8, in the substrate cleaning process using the mixed solution of ammonia water and hydrogen peroxide solution as the cleaning solution, the ammonia concentration and the hydrogen peroxide concentration in the cleaning solution are respectively maintained in appropriate ranges. Thus, the quality of the cleaning process can be kept high and uniform.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an example of the configuration of a concentration control device used for carrying out a concentration control method according to the present invention, and shows an example in which this concentration control device is used in a substrate cleaning apparatus.
FIG. 2 is a diagram illustrating an example of a flowchart for performing a series of control operations performed using the concentration control apparatus illustrated in FIG. 1;
FIG. 3 is a graph showing changes in absorbance of ultraviolet light with respect to ammonia concentration in a mixed solution when an ammonia component and a hydrogen peroxide component coexist.
[Explanation of symbols]
10 Washing tank
12 Cleaning tank liquid inlet
14 Cleaning liquid
18 Overflow liquid receiver
20 Piping for liquid circulation
22 Circulation pump
24 heater
26 Filter
28 Temperature detector
30 controller
32, 34 Chemical tank
36 Pure water supply source
38 Ammonia water supply pipe
40 Hydrogen peroxide supply pipe
42 Pure water supply pipe
44, 46, 48 Open / close control valve
50 component detector
52 Infrared absorbance measurement unit
54 Ultraviolet Absorbance Measurement Unit
56, 62 Light source
58, 64 measuring cells
60, 66 photodetector

Claims

Measure each absorbance of infrared light and ultraviolet light corresponding to the concentration of each component of ammonia and hydrogen peroxide in a mixed solution of ammonia water and hydrogen peroxide water, and based on each measured value in the mixed solution In the method for controlling the concentration of each component in the fluid mixture, the concentration of each component of ammonia and hydrogen peroxide is controlled so as to be within an appropriate range.
One of the absorbances of infrared light and ultraviolet light corresponding to the concentration of each component of ammonia and hydrogen peroxide in the mixed solution is within a predetermined range, and the other measured value is less than a predetermined lower limit value. And when both measured values are less than the predetermined lower limit, respectively, the ammonia component is replenished to the mixed solution , and then the hydrogen peroxide component is replenished to the mixed solution as necessary. A method for controlling the concentration of each component in a mixed fluid.

Depending on the measured values of each absorbance of the mixed solution of infrared light and ultraviolet light, the mixed solution is supplemented with a high concentration stock solution of ammonia water or ammonia gas is dissolved, or a high concentration stock solution of hydrogen peroxide solution is added. Replenish or add pure water,
When the measured value of one of the absorbances of ultraviolet light and infrared light of the mixed solution is within a predetermined range and the other measured value is less than a predetermined lower limit, and both measured values are respectively predetermined When the concentration becomes less than the lower limit value, replenish high concentration stock solution of ammonia water to the mixed solution or dissolve ammonia gas in the mixed solution respectively, and then add high concentration stock solution of hydrogen peroxide solution as necessary. The method for controlling the concentration of each component in the mixed fluid according to claim 1, wherein replenishment is performed or pure water is added to the mixed solution.

When the ultraviolet light absorbance of the mixed solution exceeds the predetermined upper limit, and when the ultraviolet light absorbance is within the predetermined range and the infrared light absorbance exceeds the predetermined upper limit, each of the mixed solutions is pure. Add water and replenish the mixed solution with a high-concentration stock solution of hydrogen peroxide when the absorbance of infrared light exceeds the specified upper limit and the absorbance of ultraviolet light falls below the specified lower limit. The method for controlling the concentration of each component in the mixed fluid according to claim 2.

4. The mixed fluid according to claim 2, wherein the mixed solution of ammonia water and hydrogen peroxide solution is a cleaning liquid that is contained in a cleaning tank and is used for immersing the substrate to clean the surface of the substrate. Concentration control method for each component.

And absorptiometer to measure ammonia and hydrogen peroxide and ammonia in the mixed solution and hydrogen peroxide in the respective absorbance of infrared light and ultraviolet light corresponding to the concentration of each component, respectively,
Component replenishing means for replenishing each component of ammonia and hydrogen peroxide to the mixed solution ;
Based on measurements of the absorbance of infrared light and ultraviolet light by the absorption photometer, controls the component supply devices so that the concentration of each component of ammonia and hydrogen peroxide in the mixed solution is within the proper range, respectively Replenishment control means to
In the concentration control device for each component in the mixed fluid comprising:
One of the absorbances of infrared light and ultraviolet light corresponding to the concentration of each component of ammonia and hydrogen peroxide in the mixed solution is within a predetermined range, and the other measured value is less than a predetermined lower limit value. And when both measured values are less than the predetermined lower limit, respectively, the ammonia component is replenished to the mixed solution , and then the hydrogen peroxide component is replenished to the mixed solution as necessary. As described above, the concentration control device for each component in the mixed fluid is characterized in that the component replenishment means is controlled by the replenishment control means.

Previous SL component supplement means, and the ammonia gas dissolver to dissolve the ammonia water supply unit or ammonia gas to replenish the high concentration stock solution of aqueous ammonia to the mixed solution to the mixed solution, a high concentration stock solution of hydrogen peroxide to the mixed solution A hydrogen peroxide solution supply unit for replenishment, and a pure water supply unit for adding pure water to the mixed solution.
When the measured value of one of the absorbances of ultraviolet light and infrared light of the mixed solution is within a predetermined range and the other measured value is less than a predetermined lower limit, and both measured values are respectively predetermined When the concentration becomes less than the lower limit value, replenish high concentration stock solution of ammonia water to the mixed solution or dissolve ammonia gas in the mixed solution respectively, and then add high concentration stock solution of hydrogen peroxide solution as necessary. The replenishment control means controls the ammonia water supply unit or the ammonia gas dissolving unit, the hydrogen peroxide solution supply unit, and the pure water supply unit so as to replenish or add pure water to the mixed solution. The concentration control apparatus of each component in the mixed fluid of Claim 5.

When the ultraviolet light absorbance of the mixed solution exceeds the predetermined upper limit value, and when the ultraviolet light absorbance is within the predetermined range and the infrared light absorbance exceeds the predetermined upper limit value, each of the mixed solutions is pure. Add water and replenish the mixed solution with high concentration stock solution of hydrogen peroxide when the absorbance of infrared light exceeds the specified upper limit and the absorbance of ultraviolet light falls below the specified lower limit. The concentration control device for each component in the mixed fluid according to claim 6, wherein the replenishment control means controls the pure water supply unit and the hydrogen peroxide solution supply unit.

The mixed solution of ammonia water and hydrogen peroxide water is a cleaning liquid that is contained in a cleaning tank and is used for cleaning a substrate surface by immersing the substrate in the mixed fluid according to claim 6 or 7. Concentration control device for each component.