JP3854810B2 - Method and apparatus for measuring film thickness of material to be processed by emission spectroscopy, and method and apparatus for processing material using the same - Google Patents

Description

ここで、係数ｂ，ａは、サンプリング周波数及びカットオフ周波数により数値が異なる。例えば、サンプリング周波数１０Ｈｚ，カットオフ周波数１Ｈｚの時、ａ２＝−１.１４３，ａ３＝０.４１２８，ｂ１＝０.０６７４５５，ｂ２＝０.１３４９１，ｂ３＝０.０６７４５５となる。
【００４９】
２次微係数値の時系列データｄｉは、微係数演算回路６により５点の時系列データＹｉの多項式適合平滑化微分法を用いて式（２）から以下のように算出される。

ここで、ｗ−２＝２，ｗ−１＝−１，ｗ０＝−２，ｗ１＝−１，ｗ２＝２、である。
【００５０】
前記微係数値の時系列データｄｉを用いて、平滑化微係数時系列データＤｉはデジタルフィルタ回路（２次バタワース型のローパスフィルタ、但し、デジタルフィルタ回路のａ，ｂ係数とは異なっても良い）により式（３）により求められる。

このようにして、図１の膜厚測定装置によれば、３（ａ），図３（ｂ）にＡ，Ｂ，Ｃとして示したような、複数波長についての微分値の標準パターンを少くとも１つ設定し、被処理材の干渉光の複数波長の強度をそれぞれ測定し、該測定された干渉光強度の各波長の微分値の実パターンを求め、標準パターンと微分値の実パターンとを比較することにより、被処理材の膜厚を求めることができる。例えば、膜厚３０ｎｍすなわち図２のＡを検出したい場合には、予め、膜厚Ａに対応する複数波長についての微分値の標準パターンを設定し、複数の波長において実パターンの標準パターンに対する一致率が判定値σ０以内に達したことにより、被処理材の膜厚が３０ｎｍになったことを検出できる。標準パターンとしては、１次微分値パターン，２次微分値パターンのいずれか一方あるいは両方を用いればよい。
【００５１】
この実施例によれば、境界面からの距離が例えば３０ｎｍと比較的大きい値でも、被処理材の膜厚を正確に測定することができる。
【００５２】
次に、本発明の第２実施例を図５〜図７で説明する。この実施例では、予め、所定の膜厚に対応する、複数波長についての微分値の標準パターンを基に、この標準パターンの中の１つの零通過点の波長λ０と一致したこと、及び、他の１つの波長λｐにおける微分値の実際の値の標準パターンに対する一致率が判定値σ０以内に達したことの２つの条件により、被処理材の膜厚が所定値になったことを検出できる。
【００５３】
図５において、分光器１１によりサンプリング信号として出力された２つの特定波長の信号は、時系列データｙｉ，λｏとｙｉ，λｐとしてＲＡＭ等の記憶装置（図示せず）に収納される。これらの時系列データは次に、第１デジタルフィルタ回路１２により平滑化処理され平滑化時系列データＹｉ，λｏとＹｉ，λｐとして記憶装置に収納される。これらの平滑化時系列データＹｉ，λｏとＹｉ，λｐを基に、微分器１３により微係数値（１次微分値あるいは２次微分値）の時系列データｄｉ，λｏとｄｉ，λｐが算出され、記憶装置に収納される。これらの微係数値の時系列データは、第２デジタルフィルタ回路１４により、平滑化処理され平滑化微係数時系列データＤｉ，λｏとＤｉ，λｐとして記憶装置に収納される。そして、これらの平滑化微係数時系列データＤｉ，λｏとＤｉ，λｐから干渉光強度の各波長についての微分値の実パターンが求められる。
【００５４】
一方、微分波形パターンデータベース１５には、予め、標準パターンの中の１つの零通過点の波長λ０と、他の１つの波長λｐにおける微分値の標準パターンが設定されている。微分波形比較器１６において、これらが比較され被処理材の膜厚が求められる。
【００５５】
例えば、膜厚３０ｎｍすなわち図２（ａ）のＡを検出したい場合には、図７に示すように、零通過点λ０の波長と、他の波長λｐ＝４５０ｎｍに対応する１次微分値Ｐｐを設定する。
【００５６】
なお、本実施例においても構成要素１２−１６はＣＰＵ，メモリ等を有するコンピュータにより構成して良い。
【００５７】
この実施例の動作を図６のフローチャートで説明する。まず、目標膜厚値と膜厚パターンデータベースより零通過波長λｏと、少なくとも１つの他の波長λｐと、波長λｐの微分値Ｐｐと判定値σｐの設定を行う（ステップ６００）。
【００５８】
次に、被処理材の干渉光のサンプリングを開始し（ステップ６０２）、分光器からの波長λ０とλｐの出力信号を第１段目のデジタルフィルタにより平滑化時系列データＹｉ，ｏとＹｉ，ｐを算出する（ステップ６０４）。
【００５９】
次に、Ｓ−Ｇ法により微係数ｄｉ，ｏとｄｉ，ｐを算出する(ステップ６０６)。さらに、第２段目のデジタルフィルタにより平滑化微係数時系列データＤｉ，ｏとＤｉ，ｐを算出する(ステップ６０８)。さらに、σ＝Σ（Ｄｉ，ｐ−Ｐｐ)2の算出を行う（ステップ６１０）。
【００６０】
次に、Ｄｉ−１，ｏ＊Ｄｉ，ｏ≦０ かつσ≦σ０の判定を行う（ステップ６１２）。
【００６１】
Ｄｉ−１,ｏ＊Ｄｉ,ｏの符号の正負判定において負であれば真と判定し、かつ、σ≦σ０であれば膜厚判定を終了する(ステップ６１４)。もし、Ｄｉ−１，ｏ＊Ｄｉ，ｏの符号が正、あるいはσ＞σ０であればステップ６０４に戻る。
【００６２】
この実施例によれば、２つの特定の波長に着目するだけで、すなわち図７に示す微分値パターンがλ０で零（Ｘ軸）を横切って通過したこと及び他の波長λｐの微分値Ｐｐが判定値σ０になったことにより、被処理材の膜厚を測定できる。特に、境界面からの距離が例えば３０ｎｍと比較的大きい値でも、被処理材の膜厚を正確に測定することができる。
【００６３】
本発明の第３の実施例を、図８〜図１０で説明する。この実施例では、被処理材の所定膜厚に対する干渉光のなかで、ターゲットとなる波長(ターゲット波長)λT の微分値の零通過パターンＰｊを設定し、被処理材の実際の干渉光強度の微分値の零通過パターンを求め、零通過の回数ｎから、被処理材の膜厚を求めるものである。
【００６４】
図８において、分光器１１によりサンプリング信号として出力されたターゲット波長λT の信号は、時系列データｙｉ，λT としてＲＡＭ等の記憶装置（図示せず）に収納される。この時系列データは次に、第１デジタルフィルタ回路１２により平滑化処理され平滑化時系列データＹｉ，λT として記憶装置に収納される。この平滑化時系列データを基に、微分器１３により微係数値（１次微分値あるいは２次微分値）の時系列データｄｉ，λT が算出され、記憶装置に収納される。この微係数値の時系列データは、第２デジタルフィルタ回路１４により、平滑化処理され平滑化微係数時系列データＤｉ，λT として記憶装置に収納される。一方、微分波形パターンデータベース１５には、予め、標準パターンの零通過パターンＰｊのデータが設定されている。そして、微分波形比較器１６において、この平滑化微係数時系列データが微分値の零通過パターンＰｊと比較され、零通過回数から、被処理材の膜厚を求める。
【００６５】
図９に示すように、例えば、ターゲット波長λT の３つの零通過点が、それぞれ膜厚Ａ，Ｂ，Ｃに対応する場合、微分値がこれらの零通過点を通過したことにより、Ｃ点の例えば１０ｎｍという膜厚を測定することができる。
【００６６】
なお、本実施例においても構成要素１２−１６はＣＰＵ，メモリ等を有するコンピュータにより構成して良い。
【００６７】
この実施例の動作を図１０のフローチャートで説明する。
まず、最初に目標膜厚値と膜厚パターンデータベースから、分光器の波長λT と目標零通過回数ＮT を設定してから（ステップ１０００）、サンプリングを開始する（ステップ１００２）。次に、分光器（波長λT ）からの出力信号を第１段目のデジタルフィルタにより平滑化し時系列データＹｉ，λT を算出する（ステップ１００４）。次に、Ｓ−Ｇ法により微係数ｄｉ，λT を算出する（ステップ１００６）。さらに、第２段目デジタルフィルタにより平滑化微係数時系列データＤｉ，λT を算出する（ステップ１００８）。
【００６８】
次に、（Ｄｉ−１，λT ）＊（Ｄｉ，λT ）の値符号の正負判定を行い、負＝真により微分係数の零通過を検出する（ステップ１０１０）。さらに、微分係数の零通過回数を加算（ｎ＝ｎ＋１）し（ステップ１０１２）、目標零通過回数ＮT とｎとの比較をする（ステップ１０１４）。もし、目標零通過回数ＮT に達していなかったらステップ１００４に戻り、また、目標零通過回数ＮT に達していたら所定の膜厚になったものと判定してサンプリング終了の設定を行う。
【００６９】
この実施例では、特定波長λT の微分値波形の零通過パターンＰｊを設定し、実際のパターンの零通過回数から被処理材の膜厚を求めるものであり、境界面からの距離が比較的大きい値でも、被処理材の膜厚を正確に測定することができる。
【００７０】
次に、本発明による膜厚測定方法の第４の実施例を図１１〜図１４で説明する。この実施例では、被処理材の干渉光における特定の波長を、ガイド波長λG 及びターゲット波長λT として選定し、ガイド波長λG の微分値の零通過パターンから、被処理材の膜厚範囲を求め、この膜厚範囲にある被処理材の膜厚を、ターゲット波長λT の微分値の零通過パターンから求めるものである。
【００７１】
図１１において、分光器１１によりサンプリング信号として出力された２つの特定波長の信号は、時系列データｙｉ，λG とｙｉ，λT として記憶装置（図示せず）に収納される。これらの時系列データは次に、２個の第１デジタルフィルタ回路１２（１２Ａ，１２Ｂ）により平滑化処理され平滑化時系列データＹｉ，λG とＹｉ，λT として記憶装置に収納される。これらの平滑化時系列データを基に、２個の微分器１３（１３Ａ，１３Ｂ）により微係数値（１次微分値あるいは２次微分値）の時系列データｄｉ，λG とｄｉ，λT が算出され、記憶装置に収納される。これらの微係数値の時系列データは、２個の第２デジタルフィルタ回路１４（１４Ａ，１４Ｂ）により、平滑化処理され平滑化微係数時系列データＤｉ，λG とＤｉ，λT として記憶装置に収納される。一方、微分波形パターンデータベース１５には、予め、波長λG ，λT の零通過パターンＰｊのデータが設定されている。そして、２個の微分波形比較器１６（１６Ａ，１６Ｂ）において、これらの平滑化微係数時系列データが微分値の零通過パターンＰｊと比較され、被処理材の膜厚を求める。
【００７２】
なお、本実施例においても構成要素１２Ａ，１２Ｂ〜１６Ａ，１１ＢはＣＰＵ，メモリ等を有するコンピュータにより構成して良い。
【００７３】
ここで、波長λG ，λT の零通過パターンＰｊのデータの関係について、図１２，図１３で説明する。図において、ターゲット波長λT の４つの零通過点が、それぞれ膜厚Ａ，Ｂ，Ｃ，Ｄに対応し、ガイド波長λG の３つの零通過点が、それぞれ膜厚ａ，ｂ，ｃに対応している。そして、各膜厚ａ，ｂ，ｃに対応するガイド波長λG の３つの零通過点と、各目標の膜厚Ａ，Ｂ，Ｃ，Ｄすなわちターゲット波長λT の４つの零通過点の、膜厚に対する関係は図１３のようになる。
【００７４】
従って、例えば、膜厚Ｄを目標膜厚として測定する場合を考えると、膜厚ｃに対応するガイド波長λG の零通過点が膜厚Ｄに対応するターゲット波長λT の零通過点に先行して出現することがわかる。そこで、ガイド波長λG で３つの零通過点が検出され、ターゲット波長λT で４つの零通過点が検出されると、目標膜厚Ｄになっていることが分かる。
【００７５】
この実施例の動作を図１４のフローチャートで説明する。まず、目標膜厚値と膜厚パターンデータベースから、分光器のガイド波長λG とターゲット波長λT 、各波長の目標零通過回数ＮG ，ＮT を設定する（ステップ１４００）。
【００７６】
次に、ガイド波長λG の目標零通過回数ｍを知るために、分光器（波長λG ）からの出力信号を第１段目のデジタルフィルタにより平滑化時系列データＹｉ，λG を算出する（ステップ１４０２）。さらに、Ｓ−Ｇ法により微係数ｄｉ，λG を算出する（ステップ１４０４）。次に、第２段目のデジタルフィルタにより平滑化微係数時系列データＤｉ，λG を算出する（ステップ１４０６）。さらに、（Ｄｉ−１，λG ）＊（Ｄｉ，λG ）値符号の正負判定（負＝真）により微分係数の零通過を検出する（ステップ１４１０）。そして、零通過を検出したら微分係数の零通過回数を加算（ｍ＝ｍ＋１）し（ステップ１４１２）、目標零通過回数ＮG との比較を行い（ステップ１４１４）、目標零通過回数ｍに達したら、次に、ターゲット波長λT の目標零通過回数ｎを求める処理に進む。
【００７７】
ターゲット波長λT の目標零通過回数ｎを求めるために、まず、分光器（波長λT ）からの出力信号を第１段目のデジタルフィルタにより平滑化時系列データＹｉ，λT を算出する（ステップ１４１６）。次に、Ｓ−Ｇ法により微係数ｄｉ，λT を算出する（ステップ１４１８）。さらに、第２段目のデジタルフィルタにより平滑化微係数時系列データＤｉ，λT を算出する（１４２０）。次に、（Ｄｉ−１，λT ）＊（Ｄｉ，λT ）値符号の正負判定（負＝真）により微分係数の零通過を検出する（ステップ１４２２）。そして、零通過を検出したら微分係数の零通過回数を加算（ｎ＝ｎ＋１）し（ステップ１４２４）、目標零通過回数ＮT との比較を行い（ステップ１４２６）、目標零通過回数ｎに達したら、目標膜厚になっているので、その結果を記録，出力すると共にサンプリング終了の設定を行う。
【００７８】
この実施例では、ガイド波長λG とターゲット波長λT の零通過回数によって膜厚を判定するので、境界面からの距離が比較的大きい値でも、被処理材の膜厚を正確に測定することができる。
【００７９】
発明者等の実験によれば、絶縁膜の加工を例にとると、多波長についての１次微分波形パターン，２次微分波形パターンの零通過点は、図１５に示すような特性がある。すなわち、膜厚の大きい範囲では、１次微分波形パターン，２次微分波形パターンのいずれにも零通過点が現れる。しかし、膜厚が薄くなると１次微分波形パターンには零通過点が現れなくなる。従って、膜厚の大きい範囲では、１次微分波形パターン，２次微分波形パターンのいずれの波長を、ガイド波長λG あるいはターゲット波長λT にしても良い。しかし、膜厚が薄い範囲では、１次微分波形パターンの波長をガイド波長λG とし、２次微分波形パターンの波長をターゲット波長λT にするのが望ましい。図１５の特性を利用して、例えば絶縁膜を加工したい場合には、ガイド波長λG を４７５ｎｍとし、残りの膜厚が５０ｎｍの場合、ターゲット波長λT は２次微分波形パターンの波長４５５ｎｍ、あるいは１次微分波形パターンの波長４７５ｎｍとする。残りの膜厚が１５ｎｍ以下の場合、ターゲット波長λT は、２次微分波形パターンを用いる。残りの膜厚が１５ｎｍ〜３５ｎｍの場合、ターゲット波長λT は１次微分波形パターンのｍ＝１.３５ｎｍ 〜１００ｎｍの場合、１次微分波形パターンのｍ＝２を採用する。
【００８０】
以上述べた本発明の膜厚測定装置によれば、半導体デバイスの製造プロセス等における被処理材の膜厚を正確に測定することができる。従って、このシステムを利用して、被処理材のエッチングを高精度に実施する方法を提供することができる。以下、このような半導体デバイスの製造プロセスを説明する。
【００８１】
まず、図１６は、図１〜図４で説明した本発明の第１の実施例を採用したエッチング装置の構成例である。表示器１７の被処理材の膜厚のデータは、プラズマ発生装置２０に送られ、真空容器内のプラズマの発生条件を制御するのに利用される。例えば、図１７（ａ）に示すような被処理材に対して、本発明の膜厚測定装置により求めた膜厚すなわち被エッチング材のエッチングの進行状況に応じて、真空容器内のプラズマの発生条件を変更することにより、図１７（ｂ）に示すような適切な形状のエッチング処理を行うことが可能になる。
【００８２】
なお、本実施例においても構成要素１２−１６はＣＰＵ，メモリ等を有するコンピュータにより構成して良い。
【００８３】
以下、エッチング処理の手順について簡単に説明する。
最初に、被処理材に関するエッチング処理条件の設定を行う。この中には、エッチング処理される被処理材の各層の膜毎に処理パターンに応じた目標膜厚値と膜厚毎の所定の波長域（少なくとも３個の波長域）の微分パターン抽出Ｐｉと判定値σ０が含まれる。次に、被処理材を電極上に搬入し、真空容器を減圧排気する。そして、真空容器内に所定の処理ガスを導入し、プラズマを発生させて被処理材のエッチングを開始する。同時に、干渉光のサンプリングを開始するエッチングの進行に従って変化する多波長の発光強度が、光検出器により発光強度に応じた電圧の光検出信号として検出される。分光器１１の光検出信号はデジタル変換され、サンプリング信号ｙｉ，ｊを取得する。次に、分光器からの多波長出力信号ｙｉ，ｊを平滑化し、時系列データＹｉ，ｊを算出する。次に、微分処理(Ｓ−Ｇ法）により信号波形の係数(１次または２次）ｄｉを求め、さらに、平滑化微係数時系列データＤｉ，ｊを算出する。そして、σ＝Σ（Ｄｉ，ｊ−ｐｊ)2値の算出を行うと共にσ≦σ０の判定を行い、σ≦σ０の場合、被処理材の膜厚が所定値になったものとして、エッチング処理を終了し、処理ガスを排気し、被処理材を真空容器から搬出する。
【００８４】
例えば、膜厚を図２（ａ）のＣ値にしたい場合には、予め、各膜厚Ａ，Ｂ，Ｃに対応する微分値の波長依存性を示す標準パターンを設定し、複数の波長において実パターンの標準パターンに対する一致率が判定値σ０以内に達したことにより、被処理材の残りの膜厚が順次Ａ，Ｂになったことを検出して処理ガス供給などプラズマによる処理条件を適宜制御しながら処理を進め、膜厚が正確にＣとなるように制御してエッチング処理を終了する。
【００８５】
場合によっては、所定の膜厚、例えば膜厚Ａになったことを検知した状態で一旦エッチング処理を停止し、必要な処理，操作を行った後、エッチング処理を再開するようにしても良い。あるいは、膜厚を連続的に正確に測定しつつ、膜厚に応じてエッチング処理条件を連続的に変える処理を行うようにしても良い。
【００８６】
また、本発明の他の実施例の計測方法を採用して同様なプラズマエッチング制御を行っても良い。また、本発明は、プラズマＣＶＤ，スパッタ，ＣＭＰ(chemical mechanical polishing）或いは熱ＣＶＤ等の処理にも適用できる。
【００８７】
次に、図１８は、本発明の第１の実施例を採用したエッチング装置の他の構成例である。表示器１７の被処理材の膜厚のデータは制御装置１８で処理され、プラズマ発生装置２０，ガス供給装置２１，ウエハバイアス電源２２に送られ、真空容器内のプラズマの発生条件を制御するのに利用される。例えば、絶縁膜の孔加工のように被エッチング材の膜厚がかなり厚い場合、図１９（ａ），図１９（ｂ），図１９（ｃ）に示すようにエッチングを２段階の処理に分け、本発明の膜厚測定装置により測定した膜厚すなわち被エッチング材のエッチングの進行状況に応じて図１９（ｂ）、真空容器内の各種処理条件を変更することにより、図１９（ｃ）に示すように処理速度を早くしてかつ下地材に対するオーバーエッチングのない適切な形状のエッチング処理を行うことが可能になる。この場合も、本発明の他の実施例を採用して同様な制御を行っても良い。
【００８８】
なお、本実施例においても構成要素１２−１６はＣＰＵ，メモリ等を有するコンピュータにより構成して良い。
【００８９】
なお、以上述べた各実施例は、光源を有する分光器から多波長の放射光を放出し、被処理物からの反射光の干渉光を利用して膜厚を測定するものである。一方、光源を有しない分光器を用いプラズマによって放出される多波長の放射光を光源として利用しても良い。例えば、図２０に示すように、プラズマ光による被処理材上の干渉光を上面から観察すべく真空容器２の上部壁に設けたポートから光ファイバーによって干渉光を第１の分光計１１Ａに導き、分光器真空容器２の側壁に設けた他のポートから光ファイバーによってプラズマ光の状態を観察すべくこれを第２の分光計１１Ｂに導き、両分光計の光を除算器１９で処理したものを、微分器に導き、以下、既に述べた方法で処理するようにしても良い。尚、分光計１１Ａ，１１Ｂは光源を有しない。また、図２０においても、構成要素１３，１５，１６，１９はＣＰＵ、メモリ等を有するコンピュータにより構成して良い。
【００９０】
上記の方法によれば、独立した光源が不要であり、また、プラズマ光が変化しても、常に安定して正確な膜厚の計測が可能である。さらに、被処理の処理枚数が増えることによってプラズマ処理装置が経時変化して処理時間が長くなるのを検知出来るので、メンテナンスの指示を出すこともできる。
【００９１】
次に、本発明における膜厚精度を向上する実施例を説明する。実際のエッチング処理では、エッチング処理中にプラズマが変動することがある。そのために、測定される膜厚値の精度が悪くなることが起こる。図２１は下地酸化膜２.５ｎｍのポリシリコンエッチング時の膜厚変化を示したもので、●印は本発明のパターン比較により求めた各時刻の膜厚測定値を示す。エッチング初期にポリシリコンの厚みが厚くポリシリコンからの干渉光強度が弱い場合、または、エッチング処理中にプラズマ変動があった場合、膜厚測定値のバラツキがしばしば起こる。このような場合、膜厚精度を向上するために以下の処理を行う。以下の処理は、上記コンピュータのソフトウエアで行う。
【００９２】
▲１▼膜厚算出開始はポリシリコンの厚みが薄く（例えば１７５ｎｍ以下）かつプラズマ変動の少ない時刻Ｔ１、例えばエッチング処理開始から３０秒経過時から行う。時刻Ｔ１以降は、▲２▼過去の膜厚測定値を用いて、回帰直線を算出する。▲３▼その回帰直線からはずれている膜厚測定値はノイズとする（例えば、ノイズとして扱わない膜厚測定値の許容値は±１０ｎｍとする）。▲４▼ノイズを除いた膜厚測定値から回帰直線を再度算出する。▲５▼その再度算出した回帰直線から現在の膜厚値を算出し、膜厚算出値とする。以下、所定時間経過毎に上記処理▲２▼から▲５▼を繰り返し行い各時刻の膜厚算出値を求め、この膜厚算出値が最終目標膜厚値Ｔｈｆに一致するまで上記処理を行う。なお、膜厚算出値が最終目標膜厚値Ｔｈｆに達すると、エッチング処理を終了する。
【００９３】
次に、本発明におけるエッチング処理状態監視に関する実施例を説明する。上記した各時刻における膜厚算出値のデータ列を上記コンピュータ内のメモリまたは外部記録器に収納すると共に、該収容したデータ列をウェハ処理番号と関連付けてデータベース化する。このデータベースにおいて、エッチング処理終了時間が予定のエッチング処理終了時間に対して例えば±５％を超えた場合、または、エッチング処理中の適当な時間（例えば時刻Ｔ２）における膜厚算出値が、該時刻Ｔ２での目標膜厚値（図２１のＴｈ２）に対して例えば±５％を超えた場合、このウェハ処理番号のエッチング処理が異常であることを示す警告を発する。
【００９４】
この方法によれば、膜厚測定値にバラツキがあっても精度よく膜厚を算出でき、目標とする膜厚を正確に判定するエッチング処理が行える。また、エッチング処理の状態監視が行え、ウェハの不良処理枚数を最小限度に抑えることができる。
【００９５】
【発明の効果】
本発明によれば、被処理材の処理の量をより正確に検出し、あるいは制御できる半導体ウエハの処理方法および処理装置を提供できる。
【図面の簡単な説明】
【図１】本発明の一実施例による膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図２】エッチング処理途中の被処理材の縦断面形状及び干渉光の波長実パターンの例を示す図である。
【図３】図２（ａ），図２（ｂ）のＡ，Ｂ，Ｃに示す各膜厚（境界面からの距離）に対応する、干渉光の微係数値時系列データの波長をパラメータとする図である。
【図４】図１の膜厚測定装置でエッチング処理を行う際に、被処理材の膜厚を求める手順を示すフローチャートである。
【図５】本発明の第２の実施例による膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図６】図５の実施例の動作を示すフローチャートである。
【図７】図５の実施例の動作説明図である。
【図８】本発明の第３の実施例による膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図９】図８の実施例の動作を説明するためのグラフ図である。
【図１０】図８の実施例の動作を示すフローチャートである。
【図１１】本発明の第４の実施例による膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図１２】図１１の実施例において、エッチング処理される、被処理材の断面形状を示す図である。
【図１３】図１１の実施例の動作説明図である。
【図１４】図１１の実施例の動作を示すフローチャートである。
【図１５】図１１の実施例の動作説明図である。
【図１６】本発明の第５の実施例による膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図１７】図１６の実施例において、エッチング処理される被処理材の断面形状を示す図である。
【図１８】本発明の第６の実施例になる膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図１９】図１８の実施例において、エッチング処理される、被処理材の断面形状を示す図である。
【図２０】本発明の第７の実施例による膜厚測定装置を備えた半導体ウェハのエッチング装置の全体構成を示す図である。
【図２１】本発明の更に第８の実施例を説明するための、膜厚変化を示す図である。
【符号の説明】
１…エッチング装置、２…真空容器、３…プラズマ、４…被処理材、５…試料台、８…光ファイバー、１０…膜厚測定装置、１１…分光器、１２…第１デジタルフィルタ回路、１３…微分器、１４…第２デジタルフィルタ回路、１５…微分波形パターンデータベース、１６…微分波形比較器、１７…結果表示器、１８…制御装置、１９…除算器、２０…プラズマ発生装置、２１…ガス供給装置、２２…ウエハバイアス電源。[0001]
BACKGROUND OF THE INVENTION
  The present inventionBACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method and a processing apparatus for a semiconductor wafer as a processing material, and in particular, analyzes light from the semiconductor wafer for the amount of processing performed on the film of the processing material formed on the surface of the semiconductor wafer as a processing target The present invention relates to a semiconductor wafer processing method and a processing apparatus for detecting a processing state such as a processing amount.
[0002]
[Prior art]
In the manufacture of semiconductor wafers, dry etching is widely used for the removal or patterning of various material layers and especially dielectric material layers formed on the surface of the wafer. The most important for process parameter control is to accurately determine the etch endpoint to stop the etch at the desired thickness during processing of such a layer.
[0003]
During the dry etching process of the semiconductor wafer, the emission intensity of the specific wavelength in the plasma light changes with the progress of the etching of the specific film. Therefore, as one of the methods for detecting the etching end point of a semiconductor wafer, conventionally, a change in emission intensity of a specific wavelength from plasma is detected during the dry etching process, and the etching end point of a specific film is detected based on the detection result. There is a way to do it. At that time, it is necessary to prevent erroneous detection based on the fluctuation of the detected waveform due to noise. As a method for accurately detecting a change in emission intensity, for example, Japanese Patent Application Laid-Open Nos. 61-53728 and 63-200533 are known. In Japanese Patent Laid-Open No. 61-53728, noise is reduced by a moving average method, and in Japanese Patent Laid-Open No. 63-200533, noise is reduced by approximation processing by a first-order least square method.
[0004]
With the recent miniaturization and high integration of semiconductors, the aperture ratio (area to be etched of a semiconductor wafer) has been reduced, and the emission intensity of a specific wavelength taken into the photodetector from the optical sensor has become weak. As a result, the level of the sampling signal from the photodetector is reduced, and it is difficult for the end point determination unit to reliably detect the etching end point based on the sampling signal from the photodetector.
[0005]
In addition, when detecting the end point of etching and stopping the process, it is actually important that the remaining thickness of the dielectric layer is equal to a predetermined value. Conventional processes monitor the entire process using time thickness control techniques based on the assumption that the etch rate of each layer is constant. The value of the etching rate is obtained by processing a sample wafer in advance, for example. In this method, the etching process is stopped simultaneously with the elapse of time corresponding to a predetermined etching film thickness by the time monitoring method.
[0006]
However, actual films such as SiO formed by LPCVD (low pressure chemical vapor deposition) technique₂ Layers are known to have low thickness reproducibility. Thickness tolerance due to process variations during LPCVD is SiO₂ This corresponds to about 10% of the initial thickness of the layer. Therefore, the method by time monitoring is the SiO remaining on the silicon substrate.₂ The actual final thickness of the layer cannot be measured accurately. The actual thickness of the remaining layer is then measured by a standard spectroscopic interferometer technique, and if it is found to be over-etched, the wafer is discarded as rejected. become.
[0007]
In addition, in an insulating film etching apparatus, a change over time is known such that the etching rate decreases as etching is repeated. In some cases, etching may stop in the middle, and the solution is essential. In addition, it is important for the stable operation of the process to monitor the variation of the etching rate over time. However, the conventional method only monitors the time for determining the end point. There was no appropriate way to deal with major changes and fluctuations. In addition, when the etching time is as short as about 10 seconds, the end point determination must be an end point determination method that shortens the determination preparation time, and the step of the determination time needs to be sufficiently shortened, but is not necessarily sufficient. Furthermore, in the insulating film, the area to be etched is often 1% or less, and the plasma emission intensity change from the reaction product generated by etching is small. Therefore, an end point determination system that can detect even a slight change is required, but no practical and inexpensive system is found.
[0008]
On the other hand, as another method for detecting the etching end point of a semiconductor wafer, the interference disclosed in JP-A-5-179467, JP-A-8-274082, JP-A-2000-97648, JP-A-2000-106356, etc. A method of using a meter is also known. In this interferometer usage, monochromatic radiation emitted from a laser is applied at a normal incidence angle to a wafer containing a laminated structure of dissimilar materials. For example, Si_ThreeN_FourSiO on the layer₂ In the case where the layer stack is stacked, SiO₂ Synchrotron radiation reflected from the top surface of the layer and SiO₂ Layer and Si_ThreeN_FourInterference fringes are formed by the radiation reflected at the interface formed between the layers. The reflected radiation is applied to a suitable detector, which is the SiO during etching.₂ Generates a signal whose strength varies with layer thickness. As soon as the upper surface of the SiO2 layer is exposed during the etching process, the etching rate and the current etching thickness can be monitored continuously and accurately. There is also known a method of measuring a predetermined radiation emitted by plasma instead of a laser by a spectrometer.
[0009]
[Problems to be solved by the invention]
According to the method using the interferometer, the position of the boundary surface of the laminated structure is accurately measured. However, an interference fringe is formed by the radiant light reflected from the upper surface of a layer and the reflected radiant light reflected from the boundary surface, when the process reaches the boundary surface and is measured before that time. Can not. Therefore, in the actual etching process, even if the thickness is measured on-line from the interference pattern of the radiated light, and the process reaches the boundary surface and is fed back to the process control, the layer to be processed must be over-etched. In order to avoid excessive etching, it is necessary to use in combination with the time monitoring method, etc., but this requires the premise of the film thickness value, etc. Therefore, it is difficult to perform proper etching.
[0010]
The contents of the above-mentioned conventional documents are summarized as follows.
In Japanese Patent Laid-Open No. 5-179467, interference light (plasma light) is detected using three types of color filters of red, green, and blue, and etching end point detection is performed.
[0011]
In Japanese Patent Laid-Open No. 8-274082 (US Pat. No. 5,658,418), the extreme values of the interference waveform (maximum and minimum of the waveform: zero pass point of the differential waveform) are obtained by using the temporal change of the interference waveform of the two wavelengths and its differential waveform. ). The etching rate is calculated by measuring the time until the count reaches a predetermined value, the remaining etching time until the predetermined film thickness is reached is obtained based on the calculated etching rate, and the etching process is stopped based on the etching time.
[0012]
Japanese Patent Laid-Open No. 2000-97648 discloses a waveform of a difference between a light intensity pattern of interference light before processing (with wavelength as a parameter) and a light intensity pattern of interference light after processing or during processing (with wavelength as a parameter). ) And the step (film thickness) is measured by comparing the difference waveform with the difference waveform stored in the database.
[0013]
Japanese Patent Laid-Open No. 2000-106356 relates to a spin coater and determines the film thickness by measuring the temporal change of interference light over multiple wavelengths.
[0014]
In US Pat. No. 6,081,334, characteristic behavior of interfering light with respect to time is obtained by measurement and stored in a database, and the end of etching is determined by comparing the database with the measured interference waveform. This determination prompts a change in the etching process conditions.
[0015]
In the above known example, the following problems occur.
(1) As the material to be etched becomes thinner, the intensity of interference light decreases and the number of interference fringes decreases.
(2) When etching is performed using a mask material (for example, a resist), interference light from the mask material is superimposed on interference light from the material to be etched.
(3) When the etching rate changes during the process, the interference waveform is distorted.
[0016]
From the above points, it has been difficult to accurately measure and control the thickness of the layer to be processed, particularly the layer to be processed in the plasma etching process, with the required measurement accuracy.
[0017]
  The purpose of the present invention is toAn object of the present invention is to provide a semiconductor wafer processing method and processing apparatus that can detect or control the amount of processing of a workpiece more accurately.
[0020]
[Means for Solving the Problems]
  In order to achieve the above-mentioned object, the inventors have determined the respective wavelengths of the interference light obtained from the surface of the semiconductor wafer.Detects the differential value of the intensity, obtains a pattern using the wavelength of the differential value as a parameter based on the differential value, and detects the processing amount of the semiconductor wafer based on the patternIs to do.
[0021]
In the present invention, the reason for using the pattern showing the wavelength dependence of the time differential value of the interference waveform is as follows.
[0022]
  Since the measurement is based on in-situ (real-time) measurement during etching, the film thickness of the film to be processed changes every moment. Therefore, time differentiation processing of the interference waveform is possible. Further, the noise of the interference waveform can be removed by this differentiation process. In addition, the refractive index of the material to be etched (for example, the nitride film of silicon and mask material)Is different.Therefore, interference light measurement over multiple wavelengthsIt becomes possible to detect characteristic changes (film thickness dependence) of each substance.
[0023]
  More specifically, the purpose isA film on the surface of the semiconductor wafer disposed in the vacuum processing chamber is processed using the plasma formed in the vacuum processing chamber.A method for processing a semiconductor wafer, comprising:During the processing, the interference light is received through a port that faces the plasma in the vacuum processing chamber and transmits interference light of a plurality of wavelengths obtained from the surface of the semiconductor wafer.Detecting a differential value of the intensity of the interference light of each of a plurality of wavelengths, and a differential value of the detected intensity of the interference light of the plurality of wavelengthsA pattern with the wavelength as a parameterThe process obtained in advance for a semiconductor wafer having substantially the same configuration as the semiconductor wafer.A pattern comprising differential values of the intensity of the interference light of the plurality of wavelengths with respect to a predetermined amount;And a method for processing a semiconductor wafer, comprising: detecting a processing amount for the film being processed.
[0024]
  Also,Predetermined processing is performed on the film on the surface of the semiconductor wafer to be processed arranged on the sample stage in the vacuum vessel using the plasma formed in the vacuum vessel.A semiconductor wafer processing apparatus comprising:A port that faces the plasma in the vacuum vessel and transmits light in the vacuum vessel;From the surface of the semiconductor wafer during the treatment.Receives interference light of multiple wavelengths via the portHaving a measuring device, detecting a differential value of the intensity of each of the plurality of wavelengths of interference light received by the measuring device, and detecting a differential value of the intensity of the detected interference light of the plurality of wavelengthsA pattern with the wavelength as a parameter;The process obtained in advance for a semiconductor wafer having substantially the same configuration as the semiconductor wafer.And a pattern of differential values of the intensity of the interference light of the plurality of wavelengths for a predetermined amount,This is achieved by a semiconductor wafer processing apparatus having a function of detecting the amount of processing for the film being processed.
[0025]
  Moreover,Adjusting the processing of the film of the semiconductor wafer based on the detected amount of processing.Is achieved.
[0026]
  Moreover,Interference of the plurality of wavelengths with respect to at least three different predetermined amounts of the processing obtained in advance for a semiconductor wafer having substantially the same configuration as the semiconductor wafer and a pattern of differential values of the intensity of interference light of the plurality of wavelengths And detecting a processing amount for the film during the processing based on a differential value pattern of light intensity.Is achieved.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention will be described below. In the following embodiments, those having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed description thereof is omitted.
[0031]
The first embodiment of the present invention will be described below with reference to FIGS. This example shows the wavelength dependence of the differential value of the interference light with respect to a predetermined film thickness of the sample processing material when plasma processing the processing material such as a semiconductor wafer (with wavelength as a parameter). Set the pattern. Next, the intensities of multiple wavelengths of interference light in the actual processing of the material to be processed having the same configuration as the sample material to be processed are measured, and the wavelength dependence of the differential value of the measured interference light intensity is shown ( The actual pattern (with the wavelength as a parameter) is obtained, and the standard pattern of the differential value is compared with the actual pattern to obtain the film thickness of the material to be processed.
[0032]
First, the overall configuration of a semiconductor wafer etching apparatus provided with the film thickness measuring apparatus of the present invention will be described with reference to FIG. The etching apparatus 1 includes a vacuum vessel 2. The etching gas introduced into the inside of the etching apparatus 1 is decomposed by microwave power or the like to form plasma. The plasma 3 etches the material to be processed 4 such as a semiconductor wafer on the sample stage 5. Is done. Multi-wavelength radiated light from a measurement light source (for example, a halogen light source) included in the spectroscope 11 of the film thickness measuring device 10 is guided into the vacuum vessel 2 by the optical fiber 8 and applied to the workpiece 4 at a vertical incident angle. . The material to be processed 4 includes a polysilicon layer, and the radiated light is interfered by the radiated light reflected by the upper surface of the polysilicon layer and the radiated light reflected by the boundary surface formed between the polysilicon layer and the base layer. Light is formed. The interference light is guided to the spectroscope 11 of the film thickness measuring device 10 through the optical fiber 8 and performs film thickness measurement and end point determination processing based on the state.
[0033]
The film thickness measuring apparatus 10 includes a spectroscope 11, a first digital filter circuit 12, a differentiator 13, a second digital filter circuit 14, a differential waveform pattern database 15, a differential waveform comparator 16, and a display that displays the results of the comparator. 17 is provided. FIG. 1 shows a functional configuration of the film thickness measuring apparatus 10, and the actual configuration of the film thickness measuring apparatus 10 excluding the display unit 17 and the spectroscope 11 includes a CPU and a film thickness measuring process. It can be composed of a ROM that holds various data such as a program and a differential waveform pattern database of interference light, a RAM that holds measurement data, and an external storage device, a data input / output device, and a communication control device. .
[0034]
The multi-wavelength emission intensities captured by the spectroscope 11 are converted into voltage signals as current detection signals corresponding to the emission intensities. Signals of a plurality of specific wavelengths output as sampling signals by the spectroscope 11 are stored in a storage device such as a RAM as time series data yij. The time series data yij is then smoothed by the first digital filter circuit 12 and stored in a storage device such as a RAM as smoothed time series data Yij. Based on the smoothed time series data Yij, the differentiator 13 calculates the differential coefficient value (the primary differential value or the secondary differential value 9 time series data dij is stored in a storage device such as a RAM. The numerical time series data dij is smoothed by the second digital filter circuit 14 and stored in a storage device such as a RAM as the smoothed differential coefficient time series data Dij, and the smoothed differential coefficient time series data Dij. Thus, an actual pattern showing the wavelength dependence of the differential value of the interference light intensity (with the wavelength as a parameter) is obtained.
[0035]
On the other hand, the differential waveform pattern database 15 is preset with differential waveform pattern data values Pj of interference light intensity corresponding to the respective wavelengths corresponding to the material of the material to be processed for film thickness measurement, for example, polysilicon. Yes. In the differential waveform comparator 16, the actual pattern and the differential waveform pattern data value Pj are compared to determine the film thickness of the material to be processed. The result is displayed on the result display 17.
[0036]
In addition, although the case where only one spectrometer 11 is shown is shown in the embodiment, a plurality of spectrometers 11 may be provided when it is desired to measure and control the in-plane of the material to be processed widely.
[0037]
FIG. 2A and FIG. 2B show examples of the longitudinal sectional shape of the material to be processed 4 during the etching process and the actual wavelength pattern of interference light. In FIG. 2A, a material to be processed (wafer) 4 includes a base material 41 on a substrate 40, and a material to be etched 42 and a mask material 43 stacked thereon. For example, when the gate film is etched, the substrate of the material 4 to be processed is SiO.₂ A polysilicon gate layer is formed on a polycrystalline base material corresponding to between the source and drain.
[0038]
The multi-wavelength light emitted from the spectroscope 11 is applied to the material to be processed 4 including a laminated structure of the material to be etched and the base material at a vertical incident angle. The radiated light 9 guided to the etched portion without the mask material 43 is a boundary surface formed between the radiated light 9A reflected from the upper surface of the etched material 42 and the etched material 42 and the base material 41. Interference light is formed by the radiated light 9B reflected by. The reflected position of the radiated light 9A changes as A, B, and C as the etching process proceeds. The reflected light is guided to the spectroscope 11 and generates a signal whose intensity changes depending on the thickness of the layer 42 to be etched.
[0039]
As shown in FIG. 2B, the smoothed time series data Yij of the interference light raw waveform (multi-wavelength) maintains a relatively large value until the distance from the boundary surface is close to zero, and rapidly increases near zero. To reduce. The right side from the point where the distance from the boundary surface is zero indicates the over-etching process. Based on the smoothed time series data Yij, the differential value time series data dij of the primary differential value or the secondary differential value is calculated. FIG. 2B shows the first and second derivative values of interference light having a wavelength of 475 nm. The primary differential value and the secondary differential value cross the zero value at a plurality of locations within a certain distance from the boundary surface. Hereinafter, a point crossing this zero value is referred to as a zero passing point.
[0040]
As is clear from FIG. 2B, the zero passing point appears even when the distance from the boundary surface, in other words, the film thickness is relatively large. This is a great difference compared to the fact that the value does not fluctuate until the raw waveform reaches the vicinity of the boundary surface, and it rapidly decreases near zero. Focusing on this fact, the present invention is characterized in that the film thickness can be accurately measured even when the film thickness is relatively large. Even if the output of the plasma is reduced, the primary differential value and the secondary differential value of the interference light maintain large values, so that accurate film thickness measurement is possible.
[0041]
3A and 3B, the wavelength of the differential value of the interference light with respect to the predetermined film thickness indicated by A, B, and C in FIG. 2A of the material to be processed (polysilicon) is used as a parameter. The standard pattern (indicating wavelength dependence) is shown as a pattern of derivative coefficient time series data dij of interference light corresponding to each film thickness (distance from the boundary surface). FIG. 3A shows the primary differential waveform pattern data of the interference light, and FIG. 3B shows the secondary differential waveform pattern data. A, B, and C in the figure indicate differential waveform pattern data at respective film thicknesses A (= 30 nm), B (= 20 nm), and C (= 10 nm) in FIG.
[0042]
As apparent from FIGS. 3A and 3B, the first-order differential waveform pattern and the second-order differential waveform pattern of the interference light are unique patterns for each material and film thickness of the material to be processed. It can also be seen that at a specific wavelength, the zero passing point, that is, the primary differential value and the secondary differential value become zero. For example, in the film thickness C, a wavelength of 500 nm is a zero passing point. Since these patterns change depending on the material of the material to be processed, data is obtained in advance through experiments etc. for various materials and film thickness ranges required for processing as primary differential waveform patterns and secondary differential waveform patterns. It is good to hold in the recording device.
[0043]
Next, the procedure for obtaining the film thickness of the material to be processed when performing the etching process with the film thickness measuring apparatus 10 of FIG. 1 will be described with reference to the flowchart of FIG.
[0044]
First, the differential pattern Pi extracted from the wavelength region (at least three wavelength regions) from the target film thickness value and the film thickness pattern database and the determination value σ0 are set (step 400). That is, according to the processing conditions of the material to be processed from the standard patterns of differential values for a plurality of wavelengths as shown in FIG. 3A and FIG. At least three standard patterns corresponding to the required film thickness are set.
[0045]
In the next step, sampling of interference light (for example, every 0.25 to 0.4 seconds) is started (step 402). That is, a sampling start command is issued with the start of the etching process. The multi-wavelength emission intensity that changes with the progress of etching is detected by the photodetector as a photodetection signal having a voltage corresponding to the emission intensity. The photodetection signal of the spectroscope 11 is digitally converted to obtain sampling signals yi, j.
[0046]
Next, the multi-wavelength output signal yi, j from the spectroscope is smoothed by the first-stage digital filter 12 to calculate time-series data Yi, j (step 404). That is, noise is reduced by the first-stage digital filter to obtain smoothed time series data yi.
[0047]
Next, the differential coefficient di, j is calculated by the SG method (step 406). That is, the coefficient (primary or secondary) di of the signal waveform is obtained by differential processing (SG method). Further, the smoothed differential coefficient time series data Di, j is calculated by the second stage digital filter 14 (step 408). Then, σ = Σ (Di, j−pj) 2 value is calculated (step 410). Next, the differential waveform comparator 16 determines σ ≦ σ0 (step 412). If σ ≦ σ0, the result is displayed on the display 17 assuming that the film thickness of the material to be processed has reached a predetermined value. To do. If σ ≦ σ0 is not satisfied, the process returns to step 404. Finally, the end of sampling is set (step 414).
[0048]
Here, calculation of the smoothed differential coefficient time series data Di will be described. As the digital filter circuit, for example, a secondary Butterworth low-pass filter is used. The smoothed time series data Yi is obtained by the equation (1) using a secondary Butterworth low-pass filter.

Here, the coefficients b and a have different numerical values depending on the sampling frequency and the cutoff frequency. For example, when the sampling frequency is 10 Hz and the cutoff frequency is 1 Hz, a2 = −1.143, a3 = 0.4128, b1 = 0.067455, b2 = 0.13491, b3 = 0.067455.
[0049]
The time-series data di of the secondary differential coefficient value is calculated by the differential coefficient calculation circuit 6 from the equation (2) as follows using the polynomial-adapted smoothing differentiation method of the 5-point time-series data Yi.

Here, w−2 = 2, w−1 = −1, w0 = −2, w1 = −1, and w2 = 2.
[0050]
Using the time-series data di of the differential coefficient value, the smoothed differential coefficient time-series data Di is a digital filter circuit (second-order Butterworth low-pass filter, but may be different from the a and b coefficients of the digital filter circuit. ) Is obtained from equation (3).

In this way, according to the film thickness measuring apparatus of FIG. 1, at least a standard pattern of differential values for a plurality of wavelengths, as indicated by A, B, and C in FIGS. Set one, measure the intensity of the multiple wavelengths of the interference light of the material to be processed, obtain the actual pattern of the differential value of each wavelength of the measured interference light intensity, and obtain the standard pattern and the actual pattern of the differential value By comparing, the film thickness of the material to be processed can be obtained. For example, when it is desired to detect a film thickness of 30 nm, that is, A in FIG. 2, a standard pattern of differential values for a plurality of wavelengths corresponding to the film thickness A is set in advance, and a match rate with respect to the standard pattern of the actual pattern at the plurality of wavelengths. Has reached within the determination value σ0, it can be detected that the film thickness of the material to be processed has reached 30 nm. As the standard pattern, either one or both of the primary differential value pattern and the secondary differential value pattern may be used.
[0051]
According to this embodiment, even when the distance from the boundary surface is relatively large, for example, 30 nm, the film thickness of the material to be processed can be accurately measured.
[0052]
Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, based on a standard pattern of differential values for a plurality of wavelengths corresponding to a predetermined film thickness, it matches the wavelength λ0 of one zero passing point in this standard pattern, and others It is possible to detect that the film thickness of the material to be processed has reached a predetermined value based on two conditions that the coincidence rate of the actual value of the differential value at one wavelength λp with respect to the standard pattern has reached within the determination value σ0.
[0053]
In FIG. 5, signals of two specific wavelengths output as sampling signals by the spectroscope 11 are stored in a storage device (not shown) such as a RAM as time-series data yi, λo and yi, λp. These time series data are then smoothed by the first digital filter circuit 12 and stored in the storage device as smoothed time series data Yi, λo and Yi, λp. Based on these smoothed time series data Yi, λo and Yi, λp, time series data di, λo and di, λp of derivative values (primary differential values or secondary differential values) are calculated by the differentiator 13. Stored in a storage device. The time series data of these differential coefficient values is smoothed by the second digital filter circuit 14 and stored in the storage device as smoothed differential coefficient time series data Di, λo and Di, λp. Then, an actual pattern of differential values for each wavelength of the interference light intensity is obtained from the smoothed differential coefficient time series data Di, λo and Di, λp.
[0054]
On the other hand, the differential waveform pattern database 15 is set in advance with a standard pattern of differential values at one wavelength λ0 of the zero passing point and another wavelength λp in the standard pattern. In the differential waveform comparator 16, these are compared to determine the film thickness of the material to be processed.
[0055]
For example, when it is desired to detect a film thickness of 30 nm, that is, A in FIG. 2A, as shown in FIG. 7, the first-order differential value Pp corresponding to the wavelength of the zero passing point λ0 and the other wavelength λp = 450 nm is obtained. Set.
[0056]
Also in this embodiment, the constituent elements 12-16 may be constituted by a computer having a CPU, a memory and the like.
[0057]
The operation of this embodiment will be described with reference to the flowchart of FIG. First, the zero-pass wavelength λo, at least one other wavelength λp, the differential value Pp of the wavelength λp, and the determination value σp are set from the target film thickness value and the film thickness pattern database (step 600).
[0058]
Next, sampling of the interference light of the material to be processed is started (step 602), and the output signals of the wavelengths λ0 and λp from the spectroscope are smoothed by the first stage digital filter Yi, o and Yi, p is calculated (step 604).
[0059]
Next, the differential coefficients di, o and di, p are calculated by the SG method (step 606). Further, the smoothed differential coefficient time series data Di, o and Di, p are calculated by the second stage digital filter (step 608). Further, σ = Σ (Di, p−Pp) 2 is calculated (step 610).
[0060]
Next, Di-1, o * Di, o ≦ 0 and σ ≦ σ0 are determined (step 612).
[0061]
If the sign of Di-1, o * Di, o is negative in the positive / negative determination, it is determined to be true, and if σ ≦ σ0, the film thickness determination is terminated (step 614). If the sign of Di-1, o * Di, o is positive or σ> σ0, the process returns to step 604.
[0062]
According to this embodiment, it is only necessary to pay attention to two specific wavelengths, that is, that the differential value pattern shown in FIG. 7 has passed through zero (X axis) at λ0, and the differential values Pp of other wavelengths λp are When the determination value is σ0, the film thickness of the material to be processed can be measured. In particular, even when the distance from the boundary surface is relatively large, for example, 30 nm, the film thickness of the material to be processed can be accurately measured.
[0063]
A third embodiment of the present invention will be described with reference to FIGS. In this embodiment, a zero-pass pattern Pj having a differential value of a target wavelength (target wavelength) λT is set in the interference light with respect to a predetermined film thickness of the material to be processed, and the actual interference light intensity of the material to be processed is set. A zero-pass pattern of the differential value is obtained, and the film thickness of the material to be processed is obtained from the number n of zero passes.
[0064]
In FIG. 8, the signal of the target wavelength λT outputted as the sampling signal by the spectroscope 11 is stored in a storage device (not shown) such as a RAM as time series data yi, λT. The time series data is then smoothed by the first digital filter circuit 12 and stored in the storage device as smoothed time series data Yi, λT. Based on the smoothed time series data, the differentiator 13 calculates the derivative data (primary differential value or secondary differential value) time series data di, λT and stores it in the storage device. The time series data of the differential coefficient values is smoothed by the second digital filter circuit 14 and stored in the storage device as smoothed differential coefficient time series data Di, λT. On the other hand, the differential waveform pattern database 15 is preliminarily set with data of a zero-passing pattern Pj as a standard pattern. Then, the differential waveform comparator 16 compares the smoothed differential coefficient time series data with the zero pass pattern Pj of the differential value, and obtains the film thickness of the material to be processed from the number of zero passes.
[0065]
As shown in FIG. 9, for example, when three zero-passing points of the target wavelength λT correspond to film thicknesses A, B, and C, respectively, the differential value passes through these zero-passing points, so For example, a film thickness of 10 nm can be measured.
[0066]
Also in this embodiment, the constituent elements 12-16 may be constituted by a computer having a CPU, a memory and the like.
[0067]
The operation of this embodiment will be described with reference to the flowchart of FIG.
First, from the target film thickness value and the film thickness pattern database, the wavelength λT of the spectroscope and the target zero passage number NT are set (step 1000), and sampling is started (step 1002). Next, the output signal from the spectroscope (wavelength λT) is smoothed by the first stage digital filter to calculate time series data Yi, λT (step 1004). Next, the differential coefficients di and λT are calculated by the SG method (step 1006). Further, the smoothed differential coefficient time series data Di, λT is calculated by the second stage digital filter (step 1008).
[0068]
Next, the sign of the value sign of (Di-1, λT) * (Di, λT) is determined, and zero passage of the differential coefficient is detected when negative = true (step 1010). Further, the number of zero passes of the differential coefficient is added (n = n + 1) (step 1012), and the target zero pass number NT is compared with n (step 1014). If the target zero passage number NT has not been reached, the process returns to step 1004. If the target zero passage number NT has been reached, it is determined that the predetermined film thickness has been reached and the end of sampling is set.
[0069]
In this embodiment, a zero-pass pattern Pj having a differential waveform of a specific wavelength λT is set, and the film thickness of the material to be processed is obtained from the number of zero passes of the actual pattern, and the distance from the boundary surface is relatively large. Even with the value, the film thickness of the material to be processed can be accurately measured.
[0070]
Next, a fourth embodiment of the film thickness measuring method according to the present invention will be described with reference to FIGS. In this embodiment, the specific wavelength in the interference light of the material to be processed is selected as the guide wavelength λG and the target wavelength λT, and the film thickness range of the material to be processed is obtained from the zero pass pattern of the differential value of the guide wavelength λG. The film thickness of the material to be processed within this film thickness range is obtained from the zero-pass pattern of the differential value of the target wavelength λT.
[0071]
In FIG. 11, signals of two specific wavelengths output as sampling signals by the spectroscope 11 are stored in a storage device (not shown) as time series data yi, λG and yi, λT. These time series data are then smoothed by the two first digital filter circuits 12 (12A, 12B) and stored in the storage device as smoothed time series data Yi, λG and Yi, λT. Based on these smoothed time series data, time series data di, λG and di, λT of differential coefficient values (primary differential values or secondary differential values) are calculated by two differentiators 13 (13A, 13B). And stored in a storage device. The time series data of these differential coefficient values are smoothed by the two second digital filter circuits 14 (14A, 14B) and stored in the storage device as smoothed differential coefficient time series data Di, λG and Di, λT. Is done. On the other hand, the differential waveform pattern database 15 is preliminarily set with data of zero pass patterns Pj of wavelengths λG and λT. Then, in the two differential waveform comparators 16 (16A, 16B), the smoothed differential coefficient time series data is compared with the zero-passing pattern Pj of the differential value to obtain the film thickness of the material to be processed.
[0072]
Also in this embodiment, the constituent elements 12A, 12B to 16A, 11B may be constituted by a computer having a CPU, a memory and the like.
[0073]
Here, the relationship between the data of the zero-pass pattern Pj of the wavelengths λG and λT will be described with reference to FIGS. In the figure, four zero passing points of the target wavelength λT correspond to the film thicknesses A, B, C, and D, respectively, and three zero passing points of the guide wavelength λG correspond to the film thicknesses a, b, and c, respectively. ing. The film thicknesses of the three zero pass points of the guide wavelength λ G corresponding to the respective film thicknesses a, b, c and the four zero pass points of the target film thicknesses A, B, C, D, ie, the target wavelength λ T, are obtained. The relationship to is as shown in FIG.
[0074]
Therefore, for example, when measuring the film thickness D as the target film thickness, the zero pass point of the guide wavelength λG corresponding to the film thickness c precedes the zero pass point of the target wavelength λT corresponding to the film thickness D. You can see that it appears. Thus, when three zero-passing points are detected at the guide wavelength λG and four zero-passing points are detected at the target wavelength λT, it can be seen that the target film thickness D is reached.
[0075]
The operation of this embodiment will be described with reference to the flowchart of FIG. First, from the target film thickness value and the film thickness pattern database, the spectroscope guide wavelength λ G, the target wavelength λ T, and the target zero passage times NG and NT for each wavelength are set (step 1400).
[0076]
Next, in order to know the target zero-passage number m of the guide wavelength λG, smoothed time series data Yi, λG is calculated from the output signal from the spectroscope (wavelength λG) by the first stage digital filter (step 1402). ). Further, the differential coefficients di and λG are calculated by the SG method (step 1404). Next, the smoothed differential coefficient time series data Di, λ G is calculated by the second stage digital filter (step 1406). Further, the zero passage of the differential coefficient is detected by the positive / negative determination (negative = true) of the (Di-1, λG) * (Di, λG) value sign (step 1410). When zero passage is detected, the number of zero passages of the differential coefficient is added (m = m + 1) (step 1412) and compared with the target zero passage number NG (step 1414). When the target zero passage number m is reached, Next, the process proceeds to a process of obtaining the target zero passage number n of the target wavelength λT.
[0077]
In order to obtain the target zero-passage number n of the target wavelength λT, first, smoothed time series data Yi, λT is calculated from the output signal from the spectroscope (wavelength λT) by the first stage digital filter (step 1416). . Next, the differential coefficients di, λT are calculated by the SG method (step 1418). Further, the smoothed differential coefficient time series data Di, λT is calculated by the second stage digital filter (1420). Next, zero passage of the differential coefficient is detected by positive / negative judgment (negative = true) of the (Di-1, λT) * (Di, λT) value sign (step 1422). When zero passage is detected, the number of zero passages of the differential coefficient is added (n = n + 1) (step 1424) and compared with the target zero passage number NT (step 1426). When the target zero passage number n is reached, Since the target film thickness is reached, the result is recorded and output, and the end of sampling is set.
[0078]
In this embodiment, since the film thickness is determined by the number of zero passes of the guide wavelength λG and the target wavelength λT, the film thickness of the material to be processed can be accurately measured even when the distance from the boundary surface is relatively large. .
[0079]
According to experiments by the inventors, taking the processing of the insulating film as an example, the zero-pass points of the first-order differential waveform pattern and the second-order differential waveform pattern for multiple wavelengths have the characteristics shown in FIG. That is, in the range where the film thickness is large, a zero passing point appears in both the primary differential waveform pattern and the secondary differential waveform pattern. However, when the film thickness is reduced, the zero passing point does not appear in the first-order differential waveform pattern. Therefore, in the range where the film thickness is large, any wavelength of the primary differential waveform pattern and the secondary differential waveform pattern may be set to the guide wavelength λG or the target wavelength λT. However, in the range where the film thickness is small, it is desirable that the wavelength of the first-order differential waveform pattern is the guide wavelength λG and the wavelength of the second-order differential waveform pattern is the target wavelength λT. For example, when the insulating film is to be processed using the characteristics shown in FIG. 15, when the guide wavelength λ G is 475 nm and the remaining film thickness is 50 nm, the target wavelength λ T is the wavelength 455 nm of the second-order differential waveform pattern, or 1 The wavelength of the second derivative waveform pattern is 475 nm. When the remaining film thickness is 15 nm or less, the target wavelength λT uses a second-order differential waveform pattern. When the remaining film thickness is 15 nm to 35 nm, the target differential wavelength λ T employs the primary differential waveform pattern m = 2 when the primary differential waveform pattern m = 1.35 nm to 100 nm.
[0080]
According to the film thickness measuring apparatus of the present invention described above, it is possible to accurately measure the film thickness of a material to be processed in a semiconductor device manufacturing process or the like. Therefore, it is possible to provide a method for performing etching of a material to be processed with high accuracy using this system. Hereinafter, a manufacturing process of such a semiconductor device will be described.
[0081]
First, FIG. 16 is a configuration example of an etching apparatus that employs the first embodiment of the present invention described with reference to FIGS. Data on the film thickness of the material to be processed in the display 17 is sent to the plasma generator 20 and used to control the plasma generation conditions in the vacuum vessel. For example, with respect to the material to be processed as shown in FIG. 17 (a), the generation of plasma in the vacuum container according to the film thickness obtained by the film thickness measuring apparatus of the present invention, that is, the progress of etching of the material to be etched. By changing the conditions, it becomes possible to perform an etching process having an appropriate shape as shown in FIG.
[0082]
Also in this embodiment, the constituent elements 12-16 may be constituted by a computer having a CPU, a memory and the like.
[0083]
Hereinafter, the procedure of the etching process will be briefly described.
First, the etching process conditions for the material to be processed are set. Among these, a target film thickness value corresponding to a processing pattern for each film of each layer of the material to be etched and a differential pattern extraction Pi for a predetermined wavelength region (at least three wavelength regions) for each film thickness; The determination value σ0 is included. Next, the material to be treated is carried onto the electrode, and the vacuum container is evacuated under reduced pressure. Then, a predetermined processing gas is introduced into the vacuum container, plasma is generated, and etching of the material to be processed is started. At the same time, the multi-wavelength emission intensity that changes with the progress of the etching that starts sampling of the interference light is detected by the photodetector as a photodetection signal having a voltage corresponding to the emission intensity. The photodetection signal of the spectroscope 11 is digitally converted to obtain sampling signals yi, j. Next, the multiwavelength output signal yi, j from the spectroscope is smoothed to calculate time series data Yi, j. Next, the coefficient (primary or secondary) di of the signal waveform is obtained by differentiation (SG method), and the smoothed differential coefficient time series data Di, j is calculated. Then, σ = Σ (Di, j−pj) 2 is calculated, and σ ≦ σ0 is determined. If σ ≦ σ0, the film thickness of the material to be processed is assumed to be a predetermined value, and the etching process is performed. , The processing gas is exhausted, and the material to be processed is carried out of the vacuum container.
[0084]
For example, when it is desired to set the film thickness to the C value shown in FIG. 2A, a standard pattern indicating the wavelength dependence of the differential values corresponding to the respective film thicknesses A, B, and C is set in advance, and at a plurality of wavelengths. When the coincidence rate of the actual pattern with respect to the standard pattern reaches within the judgment value σ 0, it is detected that the remaining film thickness of the material to be processed has sequentially changed to A and B, and processing conditions by plasma such as processing gas supply are appropriately set The process proceeds while controlling, and the etching process is terminated by controlling the film thickness to be accurately C.
[0085]
In some cases, the etching process may be stopped once it has been detected that the film thickness has reached a predetermined film thickness, for example, film thickness A, and the etching process may be resumed after performing the necessary processes and operations. Or you may make it perform the process which changes an etching process condition continuously according to a film thickness, measuring a film thickness correctly continuously.
[0086]
Further, the same plasma etching control may be performed by employing the measurement method of another embodiment of the present invention. The present invention can also be applied to processes such as plasma CVD, sputtering, CMP (chemical mechanical polishing), or thermal CVD.
[0087]
Next, FIG. 18 shows another configuration example of the etching apparatus employing the first embodiment of the present invention. Data on the film thickness of the material to be processed in the display 17 is processed by the control device 18 and sent to the plasma generator 20, the gas supply device 21, and the wafer bias power source 22 to control the plasma generation conditions in the vacuum vessel. Used for For example, when the thickness of the material to be etched is considerably large as in the hole processing of the insulating film, the etching is divided into two stages as shown in FIGS. 19 (a), 19 (b), and 19 (c). FIG. 19B shows the film thickness measured by the film thickness measuring apparatus of the present invention, that is, the progress of the etching of the material to be etched. As shown, it is possible to increase the processing speed and perform etching processing with an appropriate shape without over-etching the base material. Also in this case, the same control may be performed by adopting another embodiment of the present invention.
[0088]
Also in this embodiment, the constituent elements 12-16 may be constituted by a computer having a CPU, a memory and the like.
[0089]
In each of the embodiments described above, multi-wavelength radiated light is emitted from a spectroscope having a light source, and the film thickness is measured using interference light of reflected light from an object to be processed. On the other hand, multi-wavelength radiation emitted by plasma using a spectroscope without a light source may be used as the light source. For example, as shown in FIG. 20, the interference light is guided to the first spectrometer 11A by an optical fiber from a port provided on the upper wall of the vacuum vessel 2 so as to observe the interference light on the material to be processed by the plasma light from above. In order to observe the state of the plasma light from the other port provided on the side wall of the spectrometer vacuum vessel 2 by an optical fiber, this is guided to the second spectrometer 11B, and the light from both spectrometers is processed by the divider 19, You may make it guide to a differentiator and may be made to process by the method already described below. The spectrometers 11A and 11B have no light source. Also in FIG. 20, the constituent elements 13, 15, 16, and 19 may be configured by a computer having a CPU, a memory, and the like.
[0090]
According to the above method, an independent light source is unnecessary, and even when the plasma light changes, the film thickness can be measured stably and accurately. Further, since it is possible to detect that the plasma processing apparatus is changed with time and the processing time is increased due to an increase in the number of processed objects, a maintenance instruction can be issued.
[0091]
Next, an embodiment for improving the film thickness accuracy in the present invention will be described. In an actual etching process, the plasma may fluctuate during the etching process. Therefore, the accuracy of the film thickness value to be measured is deteriorated. FIG. 21 shows the change in film thickness during polysilicon etching of the underlying oxide film of 2.5 nm. The mark ● indicates the film thickness measurement value at each time obtained by the pattern comparison of the present invention. When the thickness of the polysilicon is thick at the beginning of etching and the intensity of interference light from the polysilicon is weak, or when there is a plasma fluctuation during the etching process, variations in the measured film thickness often occur. In such a case, the following processing is performed to improve the film thickness accuracy. The following processing is performed by the software of the computer.
[0092]
(1) The film thickness calculation is started at time T1 when the thickness of the polysilicon is thin (for example, 175 nm or less) and the plasma fluctuation is small, for example, when 30 seconds have elapsed from the start of the etching process. After time T1, (2) a regression line is calculated using past film thickness measurement values. (3) The film thickness measurement value deviating from the regression line is set as noise (for example, the allowable value of the film thickness measurement value not treated as noise is ± 10 nm). (4) Calculate the regression line again from the film thickness measurement value excluding noise. (5) The current film thickness value is calculated from the recalculated regression line to obtain the film thickness calculation value. Thereafter, the processes {circle around (2)} to {circle around (5)} are repeated every predetermined time to obtain the calculated film thickness at each time, and the above processes are performed until the calculated film thickness matches the final target film thickness value Thf. When the calculated film thickness reaches the final target film thickness value Thf, the etching process is terminated.
[0093]
Next, an embodiment relating to the etching processing state monitoring in the present invention will be described. The data string of the film thickness calculation values at each time described above is stored in the memory in the computer or the external recorder, and the stored data string is associated with the wafer processing number and made into a database. In this database, when the etching process end time exceeds, for example, ± 5% with respect to the scheduled etching process end time, or the calculated film thickness at an appropriate time during the etching process (for example, time T2), If, for example, ± 5% is exceeded with respect to the target film thickness value at T2 (Th2 in FIG. 21), a warning indicating that the etching process of this wafer process number is abnormal is issued.
[0094]
According to this method, the film thickness can be accurately calculated even when there are variations in the film thickness measurement value, and the etching process for accurately determining the target film thickness can be performed. Moreover, the state of the etching process can be monitored, and the number of wafers that can be processed can be minimized.
[0095]
【The invention's effect】
  According to the present invention,It is possible to provide a semiconductor wafer processing method and processing apparatus capable of more accurately detecting or controlling the amount of processing of a workpiece.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a longitudinal cross-sectional shape of a material to be processed during an etching process and an actual wavelength pattern of interference light.
FIG. 3 shows the wavelength of derivative time-series data of interference light corresponding to each film thickness (distance from the boundary surface) shown in A, B, and C of FIGS. 2 (a) and 2 (b). FIG.
4 is a flowchart showing a procedure for obtaining a film thickness of a material to be processed when performing an etching process with the film thickness measuring apparatus of FIG. 1;
FIG. 5 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to a second embodiment of the present invention.
6 is a flowchart showing the operation of the embodiment of FIG.
FIG. 7 is an operation explanatory diagram of the embodiment of FIG. 5;
FIG. 8 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to a third embodiment of the present invention.
FIG. 9 is a graph for explaining the operation of the embodiment of FIG. 8;
FIG. 10 is a flowchart showing the operation of the embodiment of FIG.
FIG. 11 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to a fourth embodiment of the present invention.
12 is a diagram showing a cross-sectional shape of a material to be processed that is etched in the embodiment of FIG.
13 is an operation explanatory diagram of the embodiment of FIG.
14 is a flowchart showing the operation of the embodiment of FIG.
15 is an operation explanatory diagram of the embodiment of FIG.
FIG. 16 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to a fifth embodiment of the present invention.
17 is a view showing a cross-sectional shape of a material to be processed in the embodiment of FIG.
FIG. 18 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to a sixth embodiment of the present invention.
FIG. 19 is a diagram showing a cross-sectional shape of a material to be processed that is etched in the example of FIG.
FIG. 20 is a diagram showing an overall configuration of a semiconductor wafer etching apparatus provided with a film thickness measuring apparatus according to a seventh embodiment of the present invention.
FIG. 21 is a view showing a change in film thickness for explaining an eighth embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Etching apparatus, 2 ... Vacuum container, 3 ... Plasma, 4 ... Material to be processed, 5 ... Sample stand, 8 ... Optical fiber, 10 ... Film thickness measuring apparatus, 11 ... Spectroscope, 12 ... 1st digital filter circuit, 13 DESCRIPTION OF SYMBOLS ... Differentiator, 14 ... 2nd digital filter circuit, 15 ... Differential waveform pattern database, 16 ... Differential waveform comparator, 17 ... Result indicator, 18 ... Control device, 19 ... Divider, 20 ... Plasma generator, 21 ... Gas supply device, 22... Wafer bias power source.

Claims (6)

A semiconductor wafer processing method of processing a film on a surface of a semiconductor wafer disposed in a vacuum processing chamber using plasma formed in the vacuum processing chamber,
During the processing, the interference light is received through a port facing the plasma in the vacuum processing chamber and through which interference light of a plurality of wavelengths obtained from the surface of the semiconductor wafer is transmitted, and the interference light of each of the plurality of wavelengths is transmitted. Detecting a differential value of intensity;
The pattern for the predetermined amount of the processing previously obtained for a semiconductor wafer having substantially the same configuration as the pattern having the wavelength as a parameter of the differential value of the detected intensity of the interference light of the plurality of wavelengths. And a step of detecting a processing amount for the film during processing based on a differential value pattern of the intensity of interference light having a wavelength of. A method for processing a semiconductor wafer according to claim 1, comprising:
A method of processing a semiconductor wafer, comprising the step of adjusting the processing of the film of the semiconductor wafer based on the detected amount of processing. A method of processing a semiconductor wafer according to claim 1 or 2 ,
Interference of the plurality of wavelengths with respect to at least three different predetermined amounts of the processing obtained in advance for a semiconductor wafer having substantially the same configuration as the semiconductor wafer and a pattern of differential values of the intensity of interference light of the plurality of wavelengths And a step of detecting an amount of processing for the film being processed based on a pattern of differential values of light intensity. A semiconductor wafer processing apparatus for performing predetermined processing on a film on a surface of a semiconductor wafer to be processed disposed on a sample stage in a vacuum vessel, using plasma formed in the vacuum vessel,
A port that faces the plasma in the vacuum vessel and transmits light in the vacuum vessel; and a measuring device that receives interference light of a plurality of wavelengths from the surface of the semiconductor wafer through the port during the processing. Have
Detecting a differential value of the intensity of each of the interference light beams of the plurality of wavelengths received by the measuring apparatus, and a pattern using the detected wavelength of the differential value of the interference light intensity of the plurality of wavelengths as a parameter; Based on a pattern of differential values of the intensity of interference light of the plurality of wavelengths with respect to a predetermined amount of the processing obtained in advance for a semiconductor wafer having substantially the same configuration as the semiconductor wafer, the processing of the film being processed A semiconductor wafer processing apparatus having a function of detecting a quantity. The semiconductor wafer processing apparatus according to claim 4,
A semiconductor wafer processing apparatus for adjusting the processing of the film of the semiconductor wafer based on the detected amount of processing. The semiconductor wafer processing apparatus according to claim 4,
The pattern of the differential value of the intensity of the interference light of the plurality of wavelengths and the interference light of the different wavelengths with respect to at least three different predetermined amounts of the processing obtained in advance for a semiconductor wafer having substantially the same configuration as the semiconductor wafer A processing apparatus for a semiconductor wafer, which detects a processing amount for the film being processed based on a pattern of differential values of the intensity.

Images