JP4644954B2 - Polishing equipment - Google Patents

Description

【００３９】
【化２】
ＮＨ₂ ＣＨ₂ ＣＯＯＨ （２）
【００４０】
【化３】

【００４１】
【化４】
（ＣＯＯＨ）₂ （４）
【００４２】
【化５】
Ｃ₂ Ｈ₅ ＣＯＯＨ （５）
【００４３】
陽極である銅膜１０５は、陽極酸化されることにより、ＣｕＯを形成する。ここで、銅膜１０５表面の凸部と陰極部材１２０との距離ｄ１は、銅膜１０５表面の凹部と陰極部材１２０との距離ｄ２に比して、短いことから、陰極部材１２０と銅膜１０５の電位差が一定の場合には、凸部における電流密度の方が凹部に比して大きくなるため、陽極酸化が促進される。
【００４４】
図３（ｇ）に示すように、陽極酸化された銅膜（ＣｕＯ）１０５の表面は、電解溶液中のキレート剤により、キレート化される。キレート剤にキナルジン酸を用いた場合には、化学構造式（６）のキレート化合物からなる膜となり、グリシンを用いた場合には、化学構造式（７）のキレート化合物からなる膜となる。これらのキレート膜１０６は、電気抵抗が銅に比して高く、機械的強度は非常に小さい。従って、銅膜１０５の表面にキレート膜１０６が形成された後は、銅膜１０５から電解液ＥＬを通じて陰極部材１２０へ流れる電流値は低下する。陽極酸化されない前は、銅のキレート化は抑制された状態にある。
【００４５】
【化６】

【００４６】
【化７】

【００４７】
次に、図４（ｈ）に示すように、銅膜１０５の表面に形成されたキレート膜１０６の凸部を、ワイピング、機械研磨などによって選択的に除去する。なお、機械研磨によって、キレート膜１０６の凸部を除去する場合に、あらかじめ、電解液ＥＬに不図示のスラリーを含ませていても良い。また、当該キレート膜の機械的強度は非常に小さいため、基板１０１に振動を与えたり、電解液ＥＬに噴流を与えたりすることによってもキレート膜１０６を容易に除去することができる。
このとき、電気抵抗の低い銅膜１０５の凸部が電解液中に露出するため、銅膜１０５から電解液ＥＬを通じて陰極部材１２０へ流れる電流値は増加する。
【００４８】
次に、図４（ｉ）に示すように、電解液中に露出した銅膜１０５の凸部は、電気抵抗が低いこと、および陰極部材１２０との距離が短いことから集中的に陽極酸化され、陽極酸化された銅は、キレート化される。このとき、銅膜１０５から電解液ＥＬを通じて陰極部材１２０へ流れる電流値は再び低下する。
その後、キレート膜１０６の凸部を上述したワイピング、機械研磨などにより、選択的に除去し、露出した銅膜１０５が集中的に陽極酸化、キレート化され、当該キレート膜１０６の凸部を選択的に除去する工程を繰り返す。このとき、銅膜１０５から電解液ＥＬを通じて陰極部材１２０へ流れる電流値は、キレート膜１０６の除去と同時に増加し、キレート膜１０６の形成と同時に低下するという状態を繰り返す。
【００４９】
次に、図５（ｊ）に示すように、上記の工程の後、銅膜１０５が平坦化する。平坦化された当該銅膜１０５をワイピング、機械研磨等によって全面に除去することにより、銅膜１０５から電解液ＥＬを通じて陰極部材１２０へ流れる電流値は、１度最大値をとる。
【００５０】
次に、図５（ｋ）に示すように、平坦化された銅膜１０５の全面について、陽極酸化による生成キレート膜の除去工程を、バリヤ膜１０３上の余分な銅膜１０５がなくなるまで続ける。
【００５１】
次に、図５（ｌ）に示すように、当該銅膜１０５の全面を例えば上述したワイピング、機械研磨などにより除去し、バリヤ膜１０３の表面を露出させる。このとき、銅膜１０５より電気抵抗の高いバリヤ膜１０３が露出するため、キレート膜１０６除去後の電流値の値が低下し始める。当該電流値が低下し始めた時点（終点付近）で、印加電圧を小さくし、その後、電圧を印加するのを停止し、陽極酸化によるキレート化の進行を止める。ここまでのプロセスによって、銅膜１０５の初期凹凸の平坦化は達成される。
その後、配線用溝の外部に堆積されたバリヤ膜１０３を除去することにより、銅配線が形成される。
【００５２】
本実施形態に係る研磨方法によれば、電気化学的に研磨レートをアシストされた研磨であるため、通常の化学機械研磨に比して、低い加工圧力で研磨を行うことができる。このことは、単純な機械研磨と比較してもスクラッチの低減、段差緩和性能、ディッシングやエロージョンの低減などの面で非常に有利である。
また、低い加工圧力で研磨を行うことができるため、機械強度が弱く通常の化学機械研磨では破壊されてしまい易い、有機系の低誘電率膜や多孔質低誘電率絶縁膜を層間絶縁膜１０２に用いる場合に非常に有用である。
【００５３】
通常の化学機械研磨で、アルミナ粒子などを含むスラリーを使用した場合には、ＣＭＰ加工に寄与したのち磨滅せずに残留したり、銅表面に埋没することが起こる（パーティクル）が、本発明の研磨方法では、砥粒を含まないキレート剤を電解液とする機械的研磨もしくはワイピングなどでも、表面に形成されたキレート膜は機械的強度が非常に小さいため、十分に除去可能である。
また、電解電流をモニタリングすることで、研磨プロセスの管理を行うことができ、研磨プロセスの進行状態を正確に把握することが可能となる。
【００５４】
本発明に係る研磨方法は、上記の実施の形態に限定されない。
銅以外にも、上述したように、例えば、Ａｌ、Ｗ、ＷＮ、Ｃｕ、Ａｕ、Ａｇ等あるいはそれらの合金膜からなる配線層に適用することができ、上述した材料等からなるバリア膜の研磨にも適用することができる。
また、配線等以外に使用される種々の金属膜の研磨に適用することができる。
また、キレート剤の種類や、陰極部材の種類など、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
また、本発明に係る半導体装置の製造方法は上記の実施の形態に限定されない。
例えば、金属膜の研磨方法以外に係る方法は何ら限定はなく、本実施形態においては、デュアルダマシン法を例に説明したが、シングルダマシン法にも適用でき、その他、コンタクトホールもしくは配線用溝の形成方法や銅膜の形成方法、バリヤ膜の形成方法などは、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
【００５５】
（研磨装置）
図６は、本発明の実施形態に係る研磨装置の構成を示す図である。
図６に示す研磨装置は、加工ヘッド部と、電解電源６１と、研磨装置全体を制御する機能を有するコントローラー５５と、スラリー供給装置７１と、電解液供給装置８１とを備えている。
なお、図示しないが研磨装置は、クリーンルーム内に設置され、当該クリーンルーム内には、被研磨対象物のウェーハを収納したウェーハカセットを搬出入する搬出入ポートが設けられている。さらに、この搬出入ポートを通じてクリーンルーム内に搬入されたウェーハカセットと研磨装置との間でウェーハの受け渡しを行うウェーハ搬送ロボットが搬出入ポートと研磨装置の間に設置される。また、当該研磨装置により研磨された後のウェーハを洗浄するための洗浄機構が１ユニットとして構成されていてもよい。
【００５６】
加工ヘッド部は、研磨工具１１を保持し、回転させる研磨工具保持部（研磨工具回転保持手段）１０と、研磨工具保持部１０をＺ軸方向の目標位置に位置決めするＺ軸位置決め機構部（移動位置決め手段）３０と、被研磨対象物のウェーハＷを保持し回転させＸ軸方向に移動するＸ軸移動機構部（回転保持手段および相対移動手段）４０とから構成されている。
【００５７】
Ｚ軸位置決め機構部３０は、不図示のコラムに固定されたＺ軸サーボモータ３１と、Ｚ軸サーボモータ３１に接続されたボールネジ軸３１ａと、保持装置１３および主軸モータ１４に連結され、ボールネジ軸３１ａに螺合するネジ部を有するＺ軸スライダ３２と、Ｚ軸スライダ３２をＺ軸方向に移動自在に保持する不図示のコラムに設置されたガイドレール３３とを有する。
【００５８】
Ｚ軸サーボモータ３１は、Ｚ軸サーボモータ３１に接続されたＺ軸ドライバ５１から駆動電流が供給されて回転駆動される。ボールネジ軸３１ａは、Ｚ軸方向に沿って設けられ、一端がＺ軸サーボモータ３１に接続され、他端は、上記の不図示のコラムに設けられた保持部材によって、回転自在に保持され、その間に、Ｚ軸スライダ３２のネジ部と螺合されている。
上記の構成により、Ｚ軸サーボモータ３１の駆動により、ボールネジ軸３１ａが回転され、Ｚ軸スライダ３２を介して、研磨工具保持部１０に保持された研磨工具１１がＺ軸方向の任意の位置に移動位置決めされる。Ｚ軸位置決め機構部３０の位置決め精度は、例えば分解能０．１μｍ程度としている。
【００５９】
Ｘ軸移動機構部４０は、ウェーハＷをチャッキングするウェーハテーブル４２とウェーハテーブル４２を回転駆動させる駆動力を供給する駆動モータ４４と、駆動モータ４４と保持装置４５の回転軸とを連結するベルト４６と、保持装置４５に設けられた加工パン４７と、駆動モータ４４および保持装置４５が設置されたＸ軸スライダ４８と、不図示の架台に設置されたＸ軸サーボモータ４９と、Ｘ軸サーボモータ４９に接続されたボールネジ軸４９ａと、Ｘ軸スライダ４８に連結されボールネジ軸４９ａに螺合するネジ部が形成された可動部材４９ｂとから構成されている。
【００６０】
ウェーハテーブル４２は、例えば、真空吸着手段によってウェーハＷを吸着する。
加工パン４７は、使用済の電解液や、スラリー等の液体を回収するために設けられている。
駆動モータ４４は、テーブルドライバ５３に接続されており、当該テーブルドライバ５３から駆動電流が供給されることによって駆動され、この駆動電流を制御することでウェーハテーブル４２を所定の回転数で回転させることができる。
Ｘ軸サーボモータ４９は、Ｘ軸ドライバ５４に接続されており、当該Ｘ軸ドライバ５４から供給される駆動電流によって回転駆動し、Ｘ軸スライダ４８がボールネジ軸４９ａおよび可動部材４９ｂを介してＸ軸方向に駆動する。このとき、Ｘ軸サーボモータ４９に供給する駆動電流を制御することによって、ウェーハテーブル４２のＸ軸方向の速度制御が可能となる。
【００６１】
スラリー供給装置７１は、スラリーを不図示の供給ノズルを介して、ウェーハＷ上に供給する。スラリーとしては、例えば、過酸化水素、硝酸鉄、ヨウ素酸カリウム等をベースとした酸化力のある水溶液に酸化アルミニウム（アルミナ）、酸化セリウム、シリカ、酸化ゲルマニウム等を研磨砥粒として含有させたものを使用する。なお、スラリーは必要に応じて供給すればよい。
【００６２】
電解液供給装置８１は、電解質と添加剤を含む電解液ＥＬを不図示の供給ノズルを介して、ウェーハＷ上に供給する。
電解質は、有機溶媒あるいは水溶液をベースとしたものを用いることができる。
電解質は、酸として、例えば、硫酸銅、硫酸アンモニウム、リン酸等があり、アルカリの例としては、エチルジアミン、ＮａＯＨ、ＫＯＨ等がある。
また、電解質として、メタノール、エタノール、グリセリン、エチレングリコール等の有機溶媒希釈混合液を用いることもできる。
添加剤としては、Ｃｕイオン、光沢剤またはキレート剤を含む。
光沢剤としては、例えば、イオウ系、水酸化銅やリン酸銅等の銅イオン系、塩酸等の塩素イオン系、ベンゾトリアゾール（ＢＴＡ）、ポリエチレングリコール等を用いることができる。
キレート剤としては、例えば、上述したキナルジン酸、グリシン、クエン酸、シュウ酸、プロピオン酸などの他、キノリン、アントラニル酸等を用いる。
【００６３】
図７は、本実施形態に係る研磨装置の研磨工具保持部１０の内部構造を示す図である。
研磨工具保持部１０は、研磨工具１１と、研磨工具１１を保持するフランジ部材１２と、フランジ部材１２を主軸１３ａを介して回転自在に保持する保持装置１３と、保持装置１３に保持された主軸１３ａを回転させる主軸モータ１４と、主軸モータ１４上に設けられたシリンダ装置１５から構成されている。
【００６４】
主軸モータ１４は、例えば、ダイレクトドライブモータからなり、このダイレクトドライブモータの不図示のロータは、主軸１３ａに連結されている。
また、主軸モータ１４は、中心部にシリンダ装置１５のピストンロッド１５ｂが挿入される貫通孔を有している。主軸モータ１４は、主軸ドライバ５２から供給される駆動電流によって駆動される。
【００６５】
保持装置１３は、例えば、エアベアリングを備えており、このエアベアリングで主軸１３ａを回転自在に保持している。保持装置１３の主軸１３ａも中心部にピストンロッド１５ｂが挿入される貫通孔を有している。
【００６６】
フランジ部材１２は、金属材料から形成されており、主軸１３ａに連結され、開口部１２ａを備え、下端面１２ｂに研磨工具１１が固着されている。
フランジ部材１２の上端面１２ｃ側は、主軸１３ａに連結されているため、主軸１３ａの回転によってフランジ部材１２も回転する。
フランジ部材１２の上端面１２ｃは、主軸モータ１４および保持装置１３の側面に設けられた導電性の通電部材２８（陰極通電部材）に固定された通電ブラシ２７と接触しており、通電ブラシ２７とフランジ部材１２とは電気的に接続されている。
【００６７】
シリンダ装置１５は、主軸モータ１４のケース上に固定されており、ピストン１５ａを内蔵しており、ピストン１５ａは、例えば、シリンダ装置１５内に供給される空気圧によって矢印Ａ１およびＡ２のいずれかの向きに駆動される。
このピストン１５ａには、ピストンロッド１５ｂが連結されており、ピストンロッド１５ｂは、主軸モータ１４および保持装置１３の中心を通って、フランジ部材１２の開口部１２ａから突き出ている。
ピストンロッド１５ｂの先端には、押圧部材２１が連結されており、この押圧部材２１はピストンロッド１５ｂに対して所定の範囲で姿勢変更が可能な連結機構によって連結されている。
押圧部材２１は、対向する位置に配置された絶縁板２２の開口２２ａの周縁部に接触可能となっており、ピストンロッド１５ｂの矢印Ａ２方向への駆動によって絶縁板２２を押圧する。
【００６８】
シリンダ装置１５のピストンロッド１５ｂの中心部には、貫通孔が形成されており、貫通孔内に通電軸２０が挿入され、ピストンロッド１５ｂに対して固定されている。
通電軸２０は、導電性材料から形成されており、上端側はシリンダ装置１５のピストン１５ａを貫通してシリンダ装置１５上に設けられたロータリジョイント１６まで伸びており、下端側は、ピストンロッド１５ｂおよび押圧部材２１を貫通して電極板２３まで伸びており、電極板２３に接続されている。
【００６９】
通電軸２０は、中心部に貫通孔が形成されており、この貫通孔が化学研磨剤（スラリー）およびキレート剤を含む電解液をウェーハＷ上に供給する供給ノズルとなっている。
また、通電軸２０は、ロータリジョイント１６と、電極板２３とを電気的に接続する役割を果たしている。
【００７０】
ロータリジョイント１６は、電解電源６１のプラス極と電気的に接続されており、通電軸２０が回転しても通電軸２０への通電を維持する。
【００７１】
通電軸２０の下端部に接続された電極板（陽極部材）２３は、金属材料からなり、特に、ウェーハＷに形成される例えば銅等の金属膜と同等または金属膜より貴なる金属で形成されている。
電極板２３は、上面側が絶縁板２２に保持されており、電極板２３の外周部は絶縁板２２に嵌合しており、下面側にはスクラブ部材２４が貼着されている。
【００７２】
絶縁板２２は、例えば、セラミクス等の絶縁材料から形成されており、この絶縁板２２は複数の棒状の連結部材２６によって主軸１３ａに連結されている。連結部材２６は、絶縁板２２の中心軸から所定の半径位置に等間隔に配置されており、主軸１３ａに対して移動自在に保持されている。このため、絶縁板２２は主軸１３ａの軸方向に移動可能である。
また、絶縁板２２と主軸１３ａとの間には、各連結部材２６に対応して、例えば、コイルスプリングからなる弾性部材２５で接続されている。
【００７３】
絶縁板２２を保持装置１３の主軸１３ａに対して移動自在にし、絶縁板２２と主軸１３ａとを弾性部材２５で連結する構成とすることにより、シリンダ装置１５に高圧エアを供給してピストンロッド１５ｂを矢印Ａ２の向きに下降させると、押圧部材２１が弾性部材２５の復元力に逆らって絶縁板２２を下方に押し下げ、これとともにスクラブ部材２４も下降する。
この状態からシリンダ装置１５への高圧エアの供給を停止すると、弾性部材２５の復元力によって、絶縁板２２は上昇し、これとともにスクラブ部材２４も上昇する。
【００７４】
研磨工具１１は、フランジ部材１２の環状の下端面１２ｂに固着されている。この研磨工具１１は、ホイール状に形成されており、下端面に環状の研磨面１１ａを備えている。研磨工具１１は、導電性を有しており、好ましくは、比較的軟質性の材料で形成する。例えば、バインダマトリクス（結合剤）自体が導電性を持つカーボンや、あるいは、焼結銅、メタルコンパウンド等の導電性材料を含有するウレタン樹脂、メラミン樹脂、エポキシ樹脂、ポリビニルアセタール（ＰＶＡ）などの樹脂からなる多孔質体から形成することができる。
研磨工具１１は、導電性を有するフランジ部材１２に直接接続され、フランジ部材１２に接触する通電ブラシ２７から通電される。
すなわち、主軸モータ１４および保持装置１３の側面に設けられた導電性の通電部材２８は、電解電源６１のマイナス極と電気的に接続され、通電部材２８に設けられた通電ブラシ２７はフランジ部材１２の上端面１２ｃに接触しており、これにより、研磨工具１１は電解電源６１と通電部材２８、通電ブラシ２７およびフランジ部材１２を介して電気的に接続されている。
【００７５】
電解電源（電流供給手段）６１は、上記したロータリジョイント１６と通電部材（陰極通電部材）２８との間に所定の電圧を印加する装置である。ロータリジョイント１６と通電部材２８との間に電圧を印加することによって、研磨工具１１とスクラブ部材２４との間には電位差が発生する。
電解電源６１には、常に一定の電圧を出力する定電圧電源ではなく、好ましくは、電圧を一定周期でパルス状に出力する、例えば、スイッチング・レギュレータ回路を内蔵した電源を使用する。
具体的には、パルス状の電圧を一定周期で出力し、パルス幅を適宜変更可能な電源を使用する。一例としては、出力電圧がＤＣ２〜５Ｖ、最大出力電流が２〜３Ａ、パルス幅が１，２，５，１０，２０，５０ｍｓｅｃのいずれかに変更可能なものを使用する。
上記のような幅が短いパルス状の電圧出力とするのは、１パルス当たりの陽極酸化量を非常に小さくするためである。すなわち、ウェーハＷの表面に形成された例えば銅等の金属膜の凹凸に接触した場合などにみられる極間距離の急変による放電、気泡やパーティクルなどが介在した場合におこる電気抵抗の急変によるスパーク放電など、金属膜の突発的かつ巨大な陽極酸化を防止し、できる限り小さなものの連続にするために有効である。
また、出力電流に比して出力電圧が比較的高いため、極間距離の設定にある程度のマージンを設定する事ができる。すなわち、極間距離が多少変わっても出力電圧が高いため電流値変化は小さい。
なお、印加するパルスとしては、上記に限られるものでなく、周期性パルスとして矩形パルス、サイン波形、鋸歯状波形、ＰＡＭ波形を印加してもよい。
【００７６】
電解電源６１には、本発明の電流検出手段としての電流計６２を備えており、この電流計６２は、電解電源６１に流れる電解電流をモニタするために設けられており、モニタした電流値信号６２ｓをコントーラ５５に出力する。
また、電解電源６１は、電流検出手段に変わって抵抗値検出手段としての抵抗計を備えていてもよく、その役割は電流検出手段と同様である。
【００７７】
コントローラ５５は、研磨装置の全体を制御する機能を有し、具体的には、主軸ドライバ５２に対して制御信号５２ｓを出力して研磨工具１１の回転数を制御し、Ｚ軸ドライバ５１に対して制御信号５１ｓを出力して研磨工具１１のＺ軸方向の位置決め制御を行い、テーブルドライバ５３に対して制御信号５３ｓを出力してウェーハＷの回転数を制御し、Ｘ軸ドライバ５４に対して制御信号５４ｓを出力して、ウェーハＷのＸ軸方向の速度制御を行う。
また、コントローラ５５は、電解液供給装置８１およびスラリー供給装置７１の動作を制御し、電解液ＥＬおよびスラリーＳＬの供給動作を制御する。
【００７８】
また、コントローラ５５は、電解電源６１の出力電圧、出力パルスの周波数、出力パルスの幅等を制御可能となっている。
また、コントローラ５５には、電解電源６１の電流計６２からの電流値信号６２ｓが入力される。コントローラ５５は、これら電流値信号６２ｓに基づいて、研磨装置の動作を制御可能となっている。具体的には、電流値信号６２ｓから得られる電解電流が一定となるように、電流値信号６２ｓをフィードバック信号としてＺ軸サーボモータ３１を制御したり、電流値信号６２ｓで特定される電流値に基づいて、研磨加工を停止させるように研磨装置の動作を制御する。
陰極部材と前記金属膜を流れる電流がステップ状に変化するように設定された周期性パルスを印加することが可能であり、例えば金属膜除去の初期においては、陰極部材と金属膜を流れる電流が徐々に増加するように設定された周期性パルスを印加する。これにより、電圧印加開始時などにおいて瞬間的に高電圧が印加されてしまい、除去される金属膜の表面状態が劣化するのを防止することができる。
また、金属膜除去の終点付近では、電流値信号６２ｓが小さくなることから、所定のしきい値と比較して、当該しきい値よりも電流値信号６２ｓが小さくなった場合には、終点付近であるとして出力パルスを小さくするように制御し、その後、パルスの出力を止めるように電解電源６１へ制御信号を出力する。
【００７９】
コントローラ５５に接続されたコントロールパネル５６は、オペレータが各種のデータを入力したり、例えば、モニタリングした電流値信号６２ｓを表示したりする。
【００８０】
ここで、図８（ａ）は電極板２３の構造の一例を示す下面図であり、図８（ｂ）は電極板２３と、通電軸２０、スクラブ部材（洗浄部材）２４および絶縁板２２との位置関係を示す断面図である。
図８（ａ）に示すように、電極板２３の中央部には円形の開口部（供給ノズル）２３ａが設けられており、この開口部２３ａを中心に電極板２３の半径方向に放射状に伸びる複数の溝部２３ｂが形成されている。
また、図８（ｂ）に示すように、電極板２３の開口部２３ａには、通電軸２０の下端部が嵌合固着されている。
【００８１】
このような構成とすることで、通電軸２０の中心部に形成された供給ノズル２０ａを通じて供給されるスラリーおよび電解液が、溝部２３ｂを通じてスクラブ部材２４の全面に拡散するようになっている。
すなわち、電極板２３、通電軸２０、スクラブ部材２４および絶縁板２２が回転しながら、スラリーおよび電解液が供給ノズル２０ａを通じてスクラブ部材２４の上側面に供給されると、スクラブ部材２４の上側面全体にスラリーおよび電解液が広がる。
なお、スクラブ部材２４および通電軸２０の供給ノズル２０ａが本発明の研磨剤供給手段および電解液供給手段の一具体例に対応している。
【００８２】
電極板２３の下面に貼着されたスクラブ部材２４は、電解液およびスラリーを吸収し、これらを上側面から下側面に通過させることができる材料から形成されている。また、このスクラブ部材２４は、ウェーハＷに接触してウェーハＷをスクラブする面を有しており、ウェーハＷ表面にスクラッチ等を発生させないように、例えば、柔らかいブラシ状の材料、スポンジ状の材料、多孔質状の材料等から形成される。例えば、ウレタン樹脂、メラミン樹脂、エポキシ樹脂、ポリビニルアセタール（ＰＶＡ）などの樹脂からなる多孔質体が挙げられる。
【００８３】
図９に、研磨する際の研磨工具１１とウェーハの位置関係を示す。
研磨工具１１の中心軸は、例えばウェーハＷに対して微小な角度で傾斜している。また、保持装置１３の主軸１３ａもウェーハＷの主面に対して研磨面１１ａの傾斜と同様に傾斜している。例えば、保持装置１３のＺ軸スライダ３２への取り付け姿勢を調整することで主軸１３ａの微小な傾斜をつくり出すことができる。
【００８４】
このように、研磨工具１１の中心軸がウェーハＷの主面に対して微小角度で傾斜していることにより、研磨工具１１の研磨面１１ａを所定の加工圧力ＦでウェーハＷに押し付けた際に、実行的な接触面積は一定に維持される。
本実施形態に係る研磨装置では、研磨工具１１の一部を部分的に研磨面１１ａとして、ウェーハＷの表面に作用させ、実効的接触領域をウェーハＷの表面に均一に走査させてウェーハＷの全面を均一に研磨する。
これにより、電解電流の値を一定に制御すれば、電流密度は常に一定とでき、金属膜の陽極酸化によるキレート化の量も常に一定にすることができる。
【００８５】
次に、上記した研磨装置による研磨動作（研磨方法）をウェーハＷ表面に形成された金属膜として例えば銅膜を研磨する場合を例に説明する。図１０は、研磨装置において研磨工具１１をＺ軸方向に下降させ、ウェーハＷの表面に接触させた状態を示す概略図である。
まず、ウェーハテーブル４２にウェーハＷをチャッキングし、ウェーハテーブル４２を駆動して所定の回転数でウェーハＷを回転させる。
また、ウェーハテーブル４２をＸ軸方向に移動して、フランジ部材１２に取り付けられた研磨工具１１をウェーハＷの上方の所定の場所に配置させ、研磨工具１１を所定の回転数で回転させる。研磨工具１１を回転させると、フランジ部材１２に連結された絶縁板２２、電極板２３およびスクラブ部材２４も回転駆動される。また、スクラブ部材２４を押圧している押圧部材２１、ピストンロッド１５ｂ、ピストン１５ａ、通電軸２０も同時に回転する。
【００８６】
この状態から、スラリー供給装置７１および電解液供給装置８１からそれぞれスラリーＳＬおよび電解液ＥＬを通電軸２０内の供給ノズル２０ａに供給すると、スクラブ部材２４の全面からスラリーＳＬおよび電解液ＥＬが供給される。
研磨工具１１をＺ軸方向に下降させて研磨工具１１の研磨面１１ａをウェーハＷの表面に接触させ、所定の加工圧力で押圧させる。
また、電解電源６１を起動させて、通電ブラシ２７を通じて研磨工具１１にマイナスの電位を印加し、ロータリジョイント１６を通じて電極板２３およびスクラブ部材２４にプラスの電位を印加する。
【００８７】
さらに、シリンダ装置１５に高圧エアを供給して、図７の矢印Ａ２の方向にピストンロッド１５ｂを下降させ、スクラブ部材２４の下面をウェーハＷに接触あるいは接近する位置まで移動させる。
この状態からウェーハテーブル４２をＸ軸方向に所定の速度パターンで移動させ、ウェーハＷの全面を一様に研磨加工する。
【００８８】
図１１は図１０の円Ｃ内の拡大図であり、図１２は図１１の円Ｄ内の拡大図である。
図１１に示すように、スクラブ部材２４はウェーハＷに形成された銅膜ＭＴを、電解液ＥＬを介して、または、直接接触することにより陽極として通電し、研磨工具１１もウェーハＷに形成された銅膜ＭＴを、電解液ＥＬを介して、または、直接接触することにより陰極として通電する。なお、図１１に示すように、銅膜ＭＴとスクラブ部材２４との間には、ギャップδ_b が存在している。さらに、図１２に示すように、銅膜ＭＴと研磨工具１１の研磨面１１ａとの間にはギャップδ_w が存在している。
図１１に示すように、絶縁板２２は、研磨工具１１とスクラブ部材２４（電極板２３）との間に介在しているが、絶縁板２２の抵抗Ｒ０は非常に大きく、したがって、スクラブ部材２４から絶縁板２２を介して研磨工具１１に流れる電流ｉ₀ はほぼ零であり、スクラブ部材２４から絶縁板２２を介して研磨工具１１には電流が流れない。
【００８９】
このため、スクラブ部材２４から研磨工具１１に流れる電流は、直接電解液ＥＬ中の抵抗Ｒ１を経由して研磨工具１１に流れる電流ｉ₁ と、電解液ＥＬ中からウェーハＷの表面に形成された銅膜ＭＴを経由して再度電解液ＥＬ中を通って研磨工具１１に流れる電流中に流れる電流ｉ₂ に分岐する。
銅膜ＭＴの表面に電流ｉ₂ が流れると、銅膜ＭＴを構成する銅は、電解液ＥＬの電解作用によって陽極酸化され、電解液中のキレート剤により、キレート化される。
【００９０】
ここで、電解液ＥＬ中の抵抗Ｒ１は、陽極としてのスクラブ部材２４と陰極としての研磨工具１１との距離ｄに比例して極端に大きくなる。このため、極間距離ｄを、ギャップδ_b およびギャップδ_w よりも十分に大きくしておくことで、直接電解液ＥＬ中の抵抗Ｒ１を経由して研磨工具１１に流れる電流ｉ₁ は非常に小さくなり、電流ｉ₂ が大きくなって、電解電流のほとんどは銅膜ＭＴの表面経由することになる。このため、銅膜ＭＴを構成する銅の陽極酸化によるキレート化を効率的に行うことができる。
また、電流ｉ₂ の大きさは、ギャップδ_b およびギャップδ_w の大きさによって変化するため、上述したように、コントローラ５５によって研磨工具１１のＺ軸方向の位置制御を行ってギャップδ_b およびギャップδ_w の大きさを調整することにより、電流ｉ₂ を一定にすることができる。ギャップδ_w の大きさの調整は、電流値信号６２ｓから得られた電解電流、すなわち、電流ｉ₂ が一定となるように、電流値信号６２ｓをフィードバック信号としてＺ軸サーボモータ３１の制御を行うことで可能である。
また、研磨装置のＺ軸方向の位置決め精度は分解能０．１μｍと十分に高く、加えて、主軸１３ａをウェーハＷの主面に対して微小角度で傾斜させていることで実行的な接触面積は常に一定に維持されることから、電解電流の値を一定に制御すれば、電流密度は常に一定とでき、銅膜の陽極酸化によるキレート化の量も常に一定にすることができる。
【００９１】
以上のように、上記構成の研磨装置は、上述したウェーハＷに形成された銅膜ＭＴの表面に、陽極酸化によるキレート膜を生成し、除去する電解研磨機能を備えている。
さらに、上記構成の研磨装置は、この電解研磨機能に加えて、研磨工具１１およびスラリーＳＬによる通常のＣＭＰ装置の化学機械研磨機能も備えており、ウェーハＷをこれら電解研磨機能および化学機械研磨の複合作用によって研磨すること（以下、電解複合研磨という）もできる。
また、上記構成の研磨装置は、スラリーＳＬを用いずに研磨工具１１の研磨面１１ａの機械的な研磨と電解研磨機能との複合作用によって研磨加工を行うこともできる。
【００９２】
本実施形態に係る研磨装置によれば、電解研磨および化学機械研磨の複合作用によって銅等の金属膜を研磨できるため、化学機械研磨のみ、あるいは、機械研磨のみを用いた研磨装置に比べてはるかに高能率に金属膜の除去を行うことができる。金属膜に対する高い研磨レートが得られるため、研磨工具１１のウェーハＷに対する加工圧力Ｆを化学機械研磨のみ、あるいは機械研磨のみを用いた研磨装置に比べて低く抑えることが可能となり、ディッシング、エロージョンの発生を抑制することができる。
【００９３】
また、通常の化学機械研磨に用いるスラリーにおいて、アルミナ粒子などを含むスラリーを使用した場合に、研磨後に、スラリーが磨滅せずに金属膜表面に残留したり、埋没することも起こるが、本実施形態に係る研磨装置では、研磨砥粒を含まないキレート剤を含む電解液を使用する機械研磨のみであっても、表面に残存するキレート膜は機械的強度が非常に低いため、十分に除去可能であることから、パーティクルやスラリーのウェーハ表面への残留を防止することができる。
【００９４】
さらに、研磨装置のＺ軸方向の位置決め精度は分解能０．１μｍと十分に高く、加えて、主軸１３ａをウェーハＷの主面に対して微小角度で傾斜させていることで実行的な接触面積は常に一定に維持されることから、電解電流の値を一定に制御すれば、電流密度は常に一定とでき、金属膜の陽極酸化によるキレート化の量も常に一定にすることができる。
上述した実施形態では、金属膜の研磨加工量の絶対値は、電解電流の積算量と研磨工具１１のウェーハＷを通過する時間で制御できる。
【００９５】
変形例１
図１３は、本発明に係る研磨装置の一変形例を示す概略図である。
上述した実施形態に係る研磨装置では、ウェーハＷ表面への通電を、導電性の研磨工具１１と、スクラブ部材２４を備えた電極板２３とによって行った。
図１３に示すように、ホイール状の研磨工具３１１に、上述した研磨装置の場合と同様に導電性を持たせるとともに、ウェーハＷをチャッキングし回転させるウェーハテーブル３４２にも導電性を持たせる構成としてもよい。研磨工具３１１への給電は、上述した実施形態と同様の構成で行う。
この場合には、ウェーハテーブル３４２への通電は、ウェーハテーブル３４２の下部にロータリージョイント３１６を設け、ロータリージョイント３１６によって回転するウェーハテーブル３４２への通電を常に維持する構成とすることで、電解電流の供給を行うことができる。
【００９６】
変形例２
図１４は、本発明に係る研磨装置の他の変形例を示す概略図である。
ウェーハＷをチャッキングし、回転させるウェーハテーブル４４２は、ウェーハＷをウェーハＷの周囲に設けたリテーナリング４１０によって保持している。
研磨工具４１１には、導電性を持たせるとともに、リテーナリング４１０にも導電性を持たせ、研磨工具４１１には上述した実施形態と同様の構成で給電する。
また、リテーナリング４１０は、ウェーハＷに形成された上記のバリア層部分まで覆い通電する。さらに、リテーナリング４１０には、ウェーハテーブル４４２の下部に設けられたロータリジョイント４１６を通じて給電する。
なお、研磨工具４１１がウェーハＷに接触しても、エッジの部分でリテーナリング４１０の厚さ以上の隙間が維持できるように研磨工具４１１の傾斜量を大きくしておくことで、研磨工具４１１とリテーナリング４１０との干渉を防ぐことができる。
【００９７】
変形例３
図１５は、本発明に係る研磨装置の他の実施形態を示す概略構成図である。
図１５に示す研磨装置は、従来型のＣＭＰ装置に本発明の電解研磨機能を付加したものであって、定盤２０１上に研磨パッド（研磨布）２０２が貼着された研磨工具の研磨面にウェーハチャック２０７によってチャッキングされたウェーハＷの全面を回転させながら接触させてウェーハＷの表面を平坦化する研磨装置である。
【００９８】
研磨パッド２０２には、陽極電極２０４と陰極電極２０３とが放射状に交互に配置されている。また、陽極電極２０４と陰極電極２０３とは絶縁体２０６によって電気的に絶縁されており、陽極電極２０４と陰極電極２０３は、定盤２０１側から通電される。これら陽極電極２０４と陰極電極２０３と絶縁体２０６とによって研磨パッド２０２は構成されている。
また、ウェーハチャック２０７は、絶縁材料から形成されている。
さらに、この研磨装置には、研磨パッド２０２の表面に電解液ＥＬおよびスラリーＳＬを供給する供給部２０８が設けられており、電解研磨および化学機械研磨を複合させた電解複合研磨が可能になっている。
【００９９】
ここで、図１６は、上記構成の研磨装置による電解複合研磨動作（研磨方法）を説明するための図である。なお、ウェーハＷ表面には、銅等の金属膜２１０が形成されているものとする。
図１６に示すように、電解複合研磨中には、ウェーハＷ表面に形成された金属膜２１０と研磨パッド２０２の研磨面との間には、電解液ＥＬおよびスラリーＳＬが介在した状態で、陽極電極２０４と陰極電極２０３との間に電圧が印加され、電流ｉが陽極電極２０４から電解液ＥＬを通って金属２１０内を伝って再び電解液ＥＬを通って陰極電極２０３に流れる。
このとき、図１６に示す円Ｇ内の付近で、金属膜２１０の表面は、陽極酸化によりキレート膜を生成し、当該キレート膜は研磨パッド２０２とスラリーＳＬによる機械的除去作用によって除去されることにより、金属膜の平坦化が達成される。
【０１００】
このような構成とすることにより、上述した実施形態に係る研磨装置と同様の効果が奏される。
なお、研磨パッドに設ける陽極電極、陰極電極の配置は図１５の構成に限定されるわけではなく、例えば、図１７に示すように、線状の複数の陽極電極２２２を縦横に等間隔に配列し、陽極電極２２２によって囲まれる各矩形領域に陰極電極２２３を配置し、陽極電極２２２と陰極電極２２３とを絶縁体２２４で電気的に絶縁した研磨パッド２２１としてもよい。
さらに、例えば、図１８に示すように、半径がそれぞれ異なる環状の陽極電極２４２を同心上に配置し、各陽極電極２４２間に形成される環状領域に陰極電極２４３をそれぞれ配置し、陽極電極２４２と陰極電極２４３とを絶縁体２４４で電気的に絶縁した研磨パッド２４１としてもよい。
【０１０１】
参考実施形態
図１９は本発明の参考実施形態に係る研磨装置の概略構成図である。本実施形態に係る研磨装置は、電解液ＥＬを所定量満たした水槽５０１と、当該水槽の電解液ＥＬ中に配置されたウェーハ保持手段５３０および電極板５１０と、水槽の電解液ＥＬを管５２２により吸い上げて管５２１により噴流として送り出すジェットポンプ５２０（流動手段）と、電極板５１０を陰極としてウェーハを陽極として電圧を印加する電源５６１（電解電流供給手段）と、電流計５６２と、コントローラ５５５およびコントロールパネル５５６から構成されている。
【０１０２】
保持手段５３０は、ウェーハを固定する導電性の第１保持部材５３１と導電性の第２保持部材５３２と、不図示のカラムなどに固定され、第１保持部材および第２保持部材を所定の位置に固定するＺ軸位置決め機構５３３とから構成されている。ウェーハの下側に位置する第２保持部材は、円形の開口部５３２ａを有している。
【０１０３】
電極板５１０は、電解液ＥＬ中にウェーハに平行に配置されており、例えば無酸素銅などにより、構成されている。
【０１０４】
電解液ＥＬは、第１実施形態と同様のものを使用することができ、例えば銅等の金属をキレート化するキレート剤を含んでおり、その他の添加剤などを含んでいても良い。例えば、電解質として、ウェーハと電極板５１０の間に印加される電圧を低下させるための、硫酸銅を用いる。
【０１０５】
電解電源（電解電流供給手段）５６１には、常に一定の電圧を出力する定電圧電源ではなく、好ましくは、電圧を一定周期でパルス状に出力する電源を使用する。例えば、電解電源５６１により印加される電圧は、２０〜５０ｍｓｅｃ毎に高電圧と低電圧を繰り返す矩形形状のパルス電圧（例えば２〜５Ｖ、電流２．２Ａ）である。
【０１０６】
上記のパルス電圧としては、ウェーハと電極板５１０との距離ｄなどにより、最も効率的に金属を除去することができる電圧およびパルス幅を選択することができる。
電極板５１０とウェーハとの距離ｄが小さすぎると、電極板５１０とウェーハとの間に介在する電解液の流動作用が十分に機能しないため、距離ｄは、所定の値以上を取ることが好ましく、上記の電圧と合わせて設定することが好ましい。
【０１０７】
電解電源５６１には、本発明の電流検出手段としての電流計５６２を備えており、この電流計５６２は、電解電源５６１に流れる電解電流をモニタするために設けられており、モニタした電流値信号５６２ｓをコントーラ５５５に出力する。
また、コントローラ５５５には、電解電源５６１の電流計５６２からの電流値信号５６２ｓが入力される。コントローラ５５５は、これら電流値信号５６２ｓに基づいて、研磨装置の動作を制御可能となっている。具体的には、電流値信号５６２ｓで特定される電流値に基づいて、研磨加工を停止させるように研磨装置の動作を制御する。
【０１０８】
コントローラ５５５に接続されたコントロールパネル５５６は、オペレータが各種のデータを入力したり、例えば、モニタリングした電流値信号５６２ｓを表示したりする。
【０１０９】
上記の研磨装置の構成によっても、第１実施形態に係る研磨装置と同様に、例えばウェーハＷの表面に凹凸のある金属膜が形成されている場合に、ウェーハＷを陽極として印加することで、ウェーハＷの金属膜表面が陽極酸化され、当該陽極酸化された金属膜が電解液ＥＬ中のキレート剤によりキレート化され、当該キレートは機械的強度が非常に弱いことから、ジェットポンプ５２０の管５２１からの電解液の流動作用によって、当該キレート膜の凸部が除去されることにより、金属膜の平坦化除去が達成される。
また、電解電流をモニタリングすることで、研磨プロセスの管理を行うことができ、研磨プロセスの進行状態を正確に把握することが可能となる。
【０１１０】
本実施形態に係る研磨装置によれば、機械的強度の非常に低いキレート膜の除去によって、金属膜の除去を達成できることから、従来の化学機械研磨のみ、あるいは、機械研磨のみを用いた研磨装置に比べてはるかに高能率に金属膜の除去を行うことができる。
従来の機械研磨のような強い押圧を必要としないため、配線金属膜下層の層間絶縁膜などに与えるダメージを低く抑えることが可能となり、ディッシング、エロージョンなどの発生を抑制することができる。配線金属膜下層の絶縁膜に高い圧力を印加しないので、該絶縁膜材料として機械的強度がＴＥＯＳなどを原料にした酸化シリコンよりも低い低誘電率材料にも適用可能である。
また、研磨装置としては、装置構成が簡便であるので、小型化を容易に実現でき、メンテナンスも容易で稼働率を向上させることができる。
【０１１１】
さらに、通常の化学機械研磨に用いるスラリーにおいて、アルミナ粒子などを含むスラリーを使用した場合に、研磨後にスラリーが磨滅せずに金属表面に残留したり、埋没することも起こるが、本実施形態に係る研磨装置では、そのような問題はない。
【０１１２】
本発明は、上記の実施形態に限定されない。例えば、ジェットポンプの構成、電極板の種類、水槽中でのウェーハを保持する装置の構成など、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
【０１１３】
第２実施形態
図２０は本発明の第２実施形態に係る研磨装置の概略構成図である。本実施形態に係る研磨装置では、パルスジェネレータ６４０、アンプ６４１、加振器６４３からなる加振手段と、電解液ＥＬを所定量満たした水槽６０１と、当該水槽の電解液ＥＬ中に配置されたウェーハ保持手段６３０および電極板６１０と、電極板６１０を陰極としてウェーハを陽極として、電圧を印加する電源６６１（電解電流供給手段）と、電流計６６２と、コントローラ６５５およびコントロールパネル６５６から構成されている。
【０１１４】
保持手段６３０は、電極板６１０をウェーハＷに対して平行に保持する第１保持部材６３１、ウェーハを介在させて圧着して固定する第２保持部材６３２と第３保持部材６３４、一端が第２保持部材６３２に取り付けられており他端が加振器６４３に取り付けられている第４保持部材６３３から構成されている。
【０１１５】
第２保持部材６３２は、導電性材料から構成されており、ウェーハＷを陽極として、通電する役割も果たす。また、第２保持部材６３２は、ウェーハの表面を電極板６１０に対して開口するための開口部分６３２ａを有している。
【０１１６】
電解液ＥＬは、第１実施形態と同様のものを使用することができ、例えば銅等の金属をキレート化するキレート剤を含んでおり、その他の添加剤などを含んでいても良い。例えば、電解質として、ウェーハと電極板５１０の間に印加される電圧を低下させるための、硫酸銅を用いる。
【０１１７】
電極板６１０は、電解液ＥＬ中にウェーハに平行に配置されており、例えば無酸素銅などにより、構成されている。
【０１１８】
電解電源（電解電流供給手段）６６１には、常に一定の電圧を出力する定電圧電源ではなく、好ましくは、電圧を一定周期でパルス状に出力する電源を使用する。例えば、電解電源６６１により印加される電圧は、２０〜５０ｍｓｅｃ毎に高電圧と低電圧を繰り返す矩形形状のパルス電圧（例えば２〜５Ｖ、電流２．２Ａ）である。
【０１１９】
上記のパルス電圧としては、ウェーハと電極板６１０との距離ｄなどにより、最も効率的に金属膜を除去することができる電圧およびパルス幅を選択することができる。
電極板６１０とウェーハとの距離ｄが小さすぎると、電極板６１０とウェーハとの間に介在する電解液の循環作用が十分に機能しないため、距離ｄは、所定の値以上を取ることが好ましく、上記の電圧と合わせて設定することが好ましい。
【０１２０】
電解電源６６１には、本発明の電流検出手段としての電流計６６２を備えており、この電流計６６２は、電解電源６６１に流れる電解電流をモニタするために設けられており、モニタした電流値信号６６２ｓをコントーラ６５５に出力する。また、コントローラ６５５には、電解電源６６１の電流計６６２からの電流値信号６６２ｓが入力される。コントローラ６５５は、これら電流値信号６６２ｓに基づいて、研磨装置の動作を制御可能となっている。具体的には、電流値信号６６２ｓで特定される電流値に基づいて、研磨加工を停止させるように研磨装置の動作を制御する。
【０１２１】
コントローラ６５５に接続されたコントロールパネル６５６は、オペレータが各種のデータを入力したり、例えば、モニタリングした電流値信号６６２ｓを表示したりする。
【０１２２】
上記の研磨装置の構成によっても、第１実施形態に係る研磨装置と同様に、例えばウェーハＷの表面に凹凸のある金属膜が形成されている場合に、ウェーハＷを陽極として印加することで、ウェーハＷの金属膜表面が陽極酸化され、当該陽極酸化された金属膜が電解液ＥＬ中のキレート剤によりキレート化され、当該キレートは機械的強度が非常に弱いことから、加振器６４３からのウェーハ振動手段によって、当該キレート膜の凸部が除去されることにより、金属膜の平坦化除去が達成される。
また、電解電流をモニタリングすることで、研磨プロセスの管理を行うことができ、研磨プロセスの進行状態を正確に把握することが可能となる。
【０１２３】
本実施形態に係る研磨装置によれば、機械的強度の非常に低いキレート膜の除去によって、金属膜の除去を達成できることから、従来の化学機械研磨のみ、あるいは、機械研磨のみを用いた研磨装置に比べてはるかに高能率に金属膜の除去を行うことができる。
従来の機械研磨のような強い押圧を必要としないため、配線金属膜下層の層間絶縁膜などに与えるダメージを低く抑えることが可能となり、ディッシング、エロージョンなどの発生を抑制することができる。配線金属膜下層の絶縁膜に高い圧力を印加しないので、該絶縁膜材料として機械的強度がＴＥＯＳなどを原料にした酸化シリコンよりも低い低誘電率材料にも適用可能である。
また、研磨装置としては、装置構成が簡便であるので、小型化を容易に実現でき、メンテナンスも容易で稼働率を向上させることができる。
【０１２４】
さらに、通常の化学機械研磨に用いるスラリーにおいて、アルミナ粒子などを含むスラリーを使用した場合に、研磨後にスラリーが磨滅せずに金属表面に残留したり、埋没することも起こるが、本実施形態に係る研磨装置では、そのような問題はない。
【０１２５】
本発明は、上記の実施形態に限定されない。例えば、加振器およびアンプの構成、電極板の種類、水槽中でのウェーハを保持する装置の構成など、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
【０１２６】
第３実施形態
図２１に本実施形態に係る研磨装置の要部構成図を示す。基本的構成は、第１実施形態と同様であるが、本実施形態では、研磨工具を使用せず、ワイピング部材２４ａによりウェーハ上の金属膜を除去する。従って、説明の簡略化のため、第１実施形態と異なる構成のみについて説明する。
【０１２７】
ワイピング部材２４ａは、例えば、電気又はイオンが通らない絶縁体で構成されその内部に気孔部を有し、当該気孔部に含有する電解液ＥＬを介してウェーハに通電することができる材料により構成されている。
上記の材料は、電解液ＥＬに侵されない材料である必要がある。
また、ワイピング部材２４ａは、ウェーハＷ表面とワイピング部材２４ａが押圧されてウェーハＷ表面の金属膜が除去されるため、ワイピング部材は、所定の強度が必要である。
例えば、ウェーハ表面Ｗの金属膜の凸部のみをワイピングするための圧力を約２０〜１００ｇ／ｃｍ² とした場合にも耐えうる弾性強度を有するとともに、スクラッチや傷等を発生しない柔らかさを有する硬度が必要である。
【０１２８】
上記の条件を満たす材料として、弾塑性体材料を使用することができ、例えばポリビニルアセタール（ＰＶＡ）、発砲ウレタン、テフロン発砲体、テフロン繊維不織布等を使用する。
また、導電性を有していてもよく、比較的軟質性の材料、例えば、バインダマトリクス（結合剤）自体が導電性を持つカーボンや、あるいは、焼結銅、メタルコンパウンド等の導電性材料を含有するウレタン樹脂、メラミン樹脂、エポキシ樹脂、ポリビニルアセタール（ＰＶＡ）などの樹脂からなる多孔質体を使用することもできる。
【０１２９】
なお、電極板２３は、ウェーハＷ表面に形成された金属膜よりも貴なる金属により構成され、ウェーハＷの表面に対して平行に配置されており、例えば、ウェーハＷ表面の金属膜の電解作用による被研磨表面から発生したガスを抜くための通気孔を設けることが好ましい。この通気孔は、ガスによる電極板２３とウェーハＷとの間の電解作用の不均一等の不利益を防止するために設けられる。
また、第１実施形態と同様、電極板２３はワイピング部材２４ａとともに回転駆動可能となっており、これにより電極板２３が回転することにより電解作用による被研磨表面から発生したガスをウェーハＷと電極板２３の間から抜くことが可能である。
また、電極板２３は、図１７および図１８で説明したように電極が領域ごとに分割された構成であってもよく、これにより被研磨表面への電解作用を部分的に選択して行うこともできる。
【０１３０】
電解電源６１は、第１実施形態と同様、上記したロータリジョイント１６およびウェーハに接触する通電ブラシ７１０との間に上記した所定のパルスを印加する。
ここで、本実施形態では、電圧印加方向が逆になっており、従って、通電ブラシ７１０が陽極、電極板２３が陰極となるように電圧を印加する。このように、通電ブラシ７１０によりウェーハＷ表面の金属膜に接触して電圧を印加する構成の他、ウェーハＷ表面の金属膜に接近可能な電極を有して電圧を印加する構成としてもよい。
具体的には、第１実施形態と同様にパルス状の電圧を一定周期で出力し、パルス幅を適宜変更可能な電源であれば特に限定はない。例えば、０Ｖを中心にプラスとマイナスを所定の周期で繰り返すＰＲ（Periodic Reverse) パルス電圧を印加する。このＰＲパルス電圧として、例えば、出力電圧が０．８〜１．２Ｖ程度の正電圧と−０．８〜−１．２Ｖ程度の逆電圧を繰り返し、電流密度が正流が１０ｍＡ／ｃｍ² で逆流が１０ｍＡ／ｃｍ² 程度、パルス幅が正流パルスが２０〜５０ｍｓｅｃで逆流パルスが５〜１０ｍｓｅｃ程度のものを使用する。
なお、印加するパルスとしては、上記に限られるものでないことは第１実施形態と同様である。
【０１３１】
通電ブラシ７１０は、ウェーハＷ表面に形成された金属膜よりも貴なる金属により構成されており、ウェーハ表面に接触して電解電源６１からの電圧をウェーハＷに導く。従って、電解電源６１から供給される電流は、ウェーハ表面の通電ブラシ７１０からウェーハＷの金属膜表面、および電解液を介して電極板２２へ流れることになる。
【０１３２】
上記の研磨装置の動作について、説明する。
まず、ウェーハテーブル４２にウェーハＷをチャッキングし、ウェーハテーブル４２を駆動して所定の回転数でウェーハＷを回転させる。
また、ウェーハテーブル４２をＸ軸方向に移動して、ワイピング部材２４ａをウェーハＷの上方の所定の場所に配置させ、ワイピング部材２４ａを所定の回転数で回転させる。例えば、ワイピング部材を、１００ｒｐｍで回転させる。
【０１３３】
この状態から、電解液供給装置８１から電解液ＥＬを通電軸２０内の供給ノズル２０ａに供給すると、ワイピング部材２４ａの全面から電解液ＥＬが供給される。
また、電解電源６１を起動させて、通電ブラシ２７を通じてウェーハ表面の金属膜にプラスの電位を印加し、ロータリジョイント１６を通じて電極板２３にマイナスの電位を印加する。
【０１３４】
これにより、通電ブラシ２７を通じてウェーハ表面の金属膜にプラスの電位が直接印加され、電解液を介して電極板２２へと電流が流れることになる。
従って、ワイピング部材２４ａ下部の金属膜を電解液を介して、陽極として通電することができ、金属膜は電解液の電解作用によって陽極酸化され、電解液中のキレート剤により、キレート化される。
【０１３５】
上記の状態で、シリンダ装置１５に高圧エアを供給して、図７の矢印Ａ２の方向にピストンロッド１５ｂを下降させ、ワイピング部材２４ａの下面をウェーハＷの表面に接触させ、所定の加工圧力で押圧させる。
この状態からウェーハテーブル４２をＸ軸方向に所定の速度パターンで移動させ、ウェーハＷの全面を一様に払拭する。
【０１３６】
以上のように、上記構成の研磨装置は、上述したウェーハＷに形成された金属膜の表面に、陽極酸化によるキレート膜を生成し、除去することができる。
【０１３７】
本実施形態に係る研磨装置によれば、第１実施形態に係る研磨装置と同様の効果を奏することができる。
さらに、本実施形態に係る研磨装置では、研磨工具を用いず、ワイピング部材２４ａによるワイピングのみでウェーハ表面の金属膜の段差を緩和できることから、ウェーハに対する押圧を第１実施形態に係る研磨装置よりもさらに小さくすることができる。
【０１３８】
なお、本実施形態では、ワイピング方法として、ワイピング部材を回転させる例を示したが、ウェーハＷに対して相対的に移動できればよく、例えば、水平運動手段を設け、ワイピング部材をウェーハＷ表面に対して水平方向に移動させることも可能である。この水平運動によるワイピングの場合、電解液が飛散することを防止するため、水平移動速度は、約１５ｍ／ｍｉｎ以下とすることが好ましい。
また、陽極酸化を促進するため、電解液の温度を８０℃以下程度に調節することが好ましい。
また、被研磨対象物表面に電解液を供給し、表面張力で電解液を保持することもできる。
さらに、被研磨対象物の例としては、特に限定はないことは上述した通りである。
【０１３９】
本発明に係る研磨装置は、上述の実施形態に限定されない。例えば、上述したように研磨対象の例としては、銅膜以外にも、アルミニウム、タングステン、金、銀等の他、それらの合金、当該合金の窒化物や酸化物等の金属膜に広く適用することができる。また、これらの金属膜は、配線用、コンタクト用等の用途に限定されない。また、本実施形態では、第１および第３実施形態においてワイピング部材２４ａや研磨工具１１をウェーハＷ上で回転させることにより払拭および研磨することとしているが、ウェーハＷに対しワイピング部材２４ａや研磨工具１１を相対移動可能であればよく、例えば、ウェーハＷ表面にワイピング部材２４ａや研磨工具１１を押圧し、ウェーハＷ表面上を水平移動させる構成をとってもよい。さらに、ウェーハへの通電方法等、本発明の要旨を逸脱しない範囲で種々の変更が可能である。
【０１４０】
【実施例】
以下に、本発明の研磨装置を用いた実施例について、図面を参照して説明する。
【０１４１】
第１実施例
図２２は、本発明の第２実施形態に係る研磨装置を用いて、陽極酸化によるキレート化により、ウェーハＷ表面の銅膜を除去した場合の銅膜の単位時間当たりの除去量と、本発明の第２実施形態に係る研磨装置において、ウェーハＷに電圧を印加せずに、電解液ＥＬ中にウェーハＷ表面の銅膜の酸化剤として、過酸化水素（Ｈ₂ Ｏ₂ ）を所定の濃度加えて、酸化によるキレート化によりウェーハＷ表面の銅膜を除去した場合の銅膜の単位時間当たりの除去量を比較したものである。
【０１４２】
図２２において、電圧を印加せずに酸化剤を加えて銅を酸化し、キレート化した後に除去したものが（Ａ）であり、電解液としてキナルジン酸溶液を用い、Ｈ₂ Ｏ₂ 濃度が０％、４．５％、８％、１０．７％における単位時間当たりの銅膜の除去量（除去速度）を測定した。なお、電解液の液量は、１５０ｍｌとした。また、本発明の第２実施形態に係る研磨装置を用いて銅膜を除去したものが（Ｂ）であり、電解液ＥＬにキナルジン酸溶液１５０ｍｌを用い、過酸化水素は含めず、電極板６１０およびウェーハＷに電解液ＥＬを介して、２．２Ａの電流が流れるよう電圧を印加したときの単位時間当たりの銅膜の除去量（除去速度）を測定した。
【０１４３】
酸化剤として過酸化水素を用いた場合に、Ｃｕは、酸化されて、銅水和イオン（［Ｃｕ（ＯＨ）₄ ］^2-）が形成される。当該銅水和イオンが電解液ＥＬ中のキレート剤によりキレート化され、例えば、キレート剤がキナルジン酸の場合には、化学構造式（６）のキレートが生成され、キレート剤がグリシンの場合には、化学構造式（７）のキレートが生成される。
【０１４４】
その他の実験条件としては、ウェーハは８インチのものを使用し、バリヤメタルとしては、厚さが２５ｎｍのＴａを用い、層間絶縁膜には、１２００ｎｍの厚さのＴＥＯＳ（tetraethylorthosilicate ）膜を用い、銅膜の厚さは１６００ｎｍのものを使用した。
【０１４５】
図２２では、酸化剤である過酸化水素の量を増やせば増やすほど、銅膜の酸化によるキレート膜の生成量が大きくなっていることから銅膜の単位時間当たりの除去量が増加していることがわかるが、本発明の第３本実施形態に係る研磨装置による研磨方法を用いた場合には、過酸化水素を加えずに、通電による銅の陽極酸化によるキレート生成のみで、酸化剤によるよりも飛躍的に除去レートが向上していることがわかる。
【０１４６】
第２実施例
図２３は、表面に銅膜を有するウェーハＷに本発明の第２実施形態に係る研磨装置を用いて、銅膜を陽極として、２．２Ａの電流を３０秒間流すごとにキレート膜を除去し、キレート膜除去後のＣｕの膜厚を測定したものである。測定部分は、８インチのウェーハを直径方向に１ポイントから２１ポイントまでに分割したときの２１ポイントの部分について測定した。１ポイントと２１ポイントはウェーハのエッジからそれぞれ６ｍｍの部分とした。なお、電解液には、キナルジン酸を使用し、Ｃｕ膜の厚さは２０００ｎｍで、バリヤメタルは膜厚２５ｎｍのＴａを用い、バリヤメタル下の層間絶縁膜には膜厚１２００ｎｍのＴＥＯＳ膜を有するウェーハＷを使用した。
【０１４７】
図２３において、横軸の０、１、２、３、４、５は、それぞれ２．２Ａの電流を３０秒間通電した回数を表している。従って、それぞれ２．２Ａの電流を、０は通電しておらず、１は３０秒間、２はトータルで６０秒間、３はトータルで９０秒間、４はトータルで１２０秒間、５はトータルで１５０秒間通電したことを示している。
縦軸には、通電後に銅を除去した後の、ウェーハ表面に残った銅の膜厚（ｎｍ）を示している。
なお、同様の条件で、当該測定を複数回行った。
【０１４８】
当該測定結果から、電流を所定時間通電するごとに、通電時間に比例して、除去後のＣｕ膜の膜厚が減少していることがわかる。なお、平均除去量は、２０２．６８ｎｍ／ｍｉｎであった。
【０１４９】
第３実施例
図２４は、直径方向に１ポイントから２１ポイントまで分割したウェーハの各ポイントにおける図２３と同様の結果を示したものである。
通電量および通電時間は、第２実施例と同様であり、２．２Ａの電流を３０秒間通電するのを複数回繰り返した場合のそれぞれの時点における除去後のＣｕ膜の膜厚を測定したものである。
用いたウェーハおよび電解液の種類などの他の条件は、第２実施例と同様である。
【０１５０】
図２４において、横軸の１ポイントから２１ポイントまでは、上述したウェーハにおける位置を示しており、縦軸には除去後の銅の膜厚（ｎｍ）を示している。
２．２Ａの電流をそれぞれ、Ａは０秒間（通電前）、Ｂは３０秒間、Ｃはトータルで６０秒間、Ｄはトータルで９０秒間、Ｅはトータルで１２０秒間、Ｆはトータルで１５０秒間通電したときのそれぞれの位置における除去後の銅の膜厚を示している。
【０１５１】
本実施例によれば、各ポイントにおける銅膜の膜厚は、ほぼ電流と時間の積に比例して、減少している。なお、１ポイントと２１ポイントの銅膜の膜厚が小さいのは、前段階であるＣｕ膜生成の際のメッキの特性からくるものであり、本発明の研磨方法には無関係である。
【０１５２】
【発明の効果】
本発明によれば、機械研磨と電解研磨との複合作用によって金属膜を研磨するので、機械研磨による金属膜の平坦化の場合に比べて、非常に高能率に金属膜の凸部の選択的除去および平坦化が可能となる。また、本発明によれば、低い研磨圧力でも十分な研磨レートが得られるため、研磨した金属膜にスクラッチ、ディッシング、エロージョン等が発生するのを抑制することができる。また、金属膜下層の絶縁膜へのダメージを抑制できることから、半導体装置の低消費電力化および高速化等の観点から誘電率を低減するために層間絶縁膜として機械的強度が比較的低い有機系低誘電率膜や多孔質低誘電率絶縁膜を使用した場合にも、容易に適用可能である。さらに、本発明によれば、電解電流をモニタリングすることで、研磨プロセスの管理を行うことができ、研磨プロセスの進行状態を正確に把握することが可能となる。
【図面の簡単な説明】
【図１】 図１は、本発明の半導体装置の製造方法の製造工程を示す断面図であり、（ａ）は半導体基板への絶縁膜形成工程まで、（ｂ）はコンタクトホールおよび配線用溝の形成工程まで、（ｃ）はバリヤ膜の形成工程までを示す。
【図２】 図２は、図１の続きの工程を示し、（ｄ）はシード膜としての銅膜の形成工程まで、（ｅ）は銅膜の形成工程までを示す。
【図３】 図３は、図２の続きの工程を示し、（ｆ）は銅膜の陽極酸化の工程まで、（ｇ）はキレート膜の形成工程までを示す。
【図４】 図４は、図３の続きの工程を示し、（ｈ）は凸部のキレート膜の除去工程まで、（ｉ）はキレート膜の再形成工程までを示す。
【図５】 図５は、図４の続きの工程を示し、（ｊ）は銅膜の平坦化工程まで、（ｋ）は余分な銅膜の除去工程まで、（ｌ）はバリヤ膜の露出工程までを示す。
【図６】 図６は、本実施形態に係る研磨装置の構成を表す図である。
【図７】 図７は、本実施形態に係る研磨装置の研磨工具保持部の内部構造を表す拡大図である。
【図８】 図８（ａ）は、本実施形態に係る研磨装置に用いる電極板の底面図であり、（ｂ）は電極板付近の拡大図である。
【図９】 図９は、研磨工具とウェーハとの位置関係を示す図である。
【図１０】 図１０は、本発明に係る研磨装置の電解研磨を説明するための断面図である
【図１１】 図１１は、図１０の円Ｃにおける拡大断面図である。
【図１２】 図１２は、図１１の円Ｄにおける拡大断面図である。
【図１３】 図１３は、本発明の係る研磨装置の第１変形例を示す図である。
【図１４】 図１４は、本発明に係る研磨装置の第２変形例を示す図である。
【図１５】 図１５は、本発明に係る研磨装置の従来型ＣＭＰ装置に応用した第３変形例を示す図である。
【図１６】 図１６は、図１５に示した研磨装置による電解複合研磨動作を説明するための図である。
【図１７】 図１７は、研磨パッドの電極構成の他の例を示す図である。
【図１８】 図１８は、研磨パッドの電極構成のさらに他の例を示す図である。
【図１９】 図１９は、本発明の参考実施形態に係る研磨装置の概略構成図である。
【図２０】 図２０は、本発明の第２実施形態に係る研磨装置の概略構成図である。
【図２１】 図２１は、本発明の第３実施形態に係る研磨装置の要部構成図である。
【図２２】 図２２は、本発明の第１実施例を説明するための図である。
【図２３】 図２３は、本発明の第２実施例を説明するための図である。
【図２４】 図２４は、本発明の第３実施例を説明するための図である。
【図２５】 図２５は、従来例に係るデュアルダマシン法による銅配線の形成方法の製造工程を示す断面図であり、（ａ）は層間絶縁膜の形成工程まで、（ｂ）は配線用溝およびコンタクトホールの形成工程まで、（ｃ）はバリヤ膜の形成工程までを示す。
【図２６】 図２６は、図２４の続きの工程を示し、（ｄ）はシード膜の形成工程まで、（ｅ）は配線用層の形成工程まで、（ｆ）は配線形成工程までを示す。
【図２７】 図２７は、ＣＭＰ法による銅膜研磨工程において発生するディッシングを説明するための断面図である。
【図２８】 図２８は、ＣＭＰ法による銅膜研磨工程において発生するエロージョンを説明するための断面図である。
【図２９】 図２９は、ＣＭＰ法による銅膜研磨工程において発生するリセスを説明するための断面図である。
【図３０】 図３０は、ＣＭＰ法による銅膜研磨工程において発生するスクラッチおよびケミカルダメージを説明するための断面図である。
【符号の説明】
１０…研磨工具保持部、１１，３１１，４１１…研磨工具、１２…フランジ部材、１３…保持装置、１３ａ…主軸、１４…主軸モータ、１５…シリンダ装置、１５ａ…ピストン、１５ｂ…ピストンロッド、１６，３１６，４１６…ロータリジョイント、２０…通電軸、２０ａ…供給ノズル、２１…押圧部材、２２…絶縁板、２３…電極板、２４…スクラブ部材、２４ａ…ワイピング部材、２５…弾性部材、２６…連結部材、２７…通電ブラシ、２８…通電部材、３０…Ｚ軸位置決め機構部、３１…Ｚ軸サーボモータ、３１ａ…ボールネジ軸、３２…Ｚ軸スライダ、３３…ガイドレール、４０…Ｘ軸移動機構部、４２，３４２，４４２…ウェーハテーブル、４４…駆動モータ、４５…保持装置、４６…ベルト、４７…加工パン、４８…Ｘ軸スライダ、４９…Ｘ軸サーボモータ、５１…Ｚ軸ドライバ、５２…主軸ドライバ、５３…テーブルドライバ、５４…Ｘ軸ドライバ、５５，５５５，６５５…コントローラ、５６，５５６，６５６…コントロールパネル、６１，５６１，６６１…電解電源、６２，５６２，６６２…電流計、６３…抵抗計、７１…スラリー供給装置、８１…電解液供給装置、１０１…半導体基板、１０２…層間絶縁膜、１０３…バリヤ膜、１０４…シード膜、１０５…銅膜、１０６…キレート膜、１２０…陰極部材、２０１…定盤、２０２，２２１，２４１…研磨パッド、２０３，２２３，２４３…陰極電極、２０４…陽極電極、２０６，２２４，２４４…絶縁体、２０７…ウェーハチャック、２０８…電解液・スラリー供給部、２１０…銅膜、４１０…リテーナリング、５０１，６０１…水槽、５１０，６１０…電極板、５２０…ジェットポンプ、５２１，５２２…管、５３１，６３１…第１保持部材、５３２，６３２…第２保持部材、５３３…Ｚ軸位置決め機構、６３４…第３保持部材、６４０…パルスジェネレータ、６４１…アンプ、６４３…加振器、６４４…第４保持部材、７１０…通電ブラシ、ＳＣ…スクラッチ、ＣＤ…ケミカルダメージ、ＥＬ…電解液、ＳＬ…スラリー。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a polishing apparatus, and more particularly, to a polishing apparatus used to relieve uneven surfaces associated with metal film formation.
[0002]
[Prior art]
Along with the high integration and miniaturization of semiconductor devices, the miniaturization of wiring, the reduction of wiring pitch, and the multilayering of wiring are progressing, and the importance of multilayer wiring technology in the manufacturing process of semiconductor devices is increasing.
On the other hand, aluminum has been widely used as a wiring material of a semiconductor device having a multilayer wiring structure. However, in order to suppress a signal propagation delay in a recent design rule of 0.25 μm rule or less, the wiring material is changed from aluminum to copper. The development of a wiring process that replaces is actively conducted. When copper is used for the wiring, there is an advantage that both low resistance and high electromigration resistance can be achieved.
[0003]
In the process of using copper for wiring, for example, a metal is embedded in a groove-shaped wiring pattern formed in advance in an interlayer insulating film, and the excess metal film is removed by CMP (Chemical Mechanical Polishing) method. The wiring process called the damascen method that is formed is influential. This damascene method does not require wiring etching, and has an advantage that the process can be simplified because the upper interlayer insulating film is naturally flat.
In addition, the dual damascene method, in which not only wiring grooves but also contact holes are formed in the interlayer insulating film as grooves and the wiring grooves and contact holes are simultaneously filled with metal, can further reduce the wiring process. Become.
[0004]
Here, an example of the copper wiring forming process by the dual damascene method will be described with reference to the following drawings.
First, as shown in FIG. 25A, for example, an interlayer insulating film 302 made of, for example, silicon oxide is formed on a semiconductor substrate 301 such as silicon on which an impurity diffusion region (not shown) is appropriately formed, for example, under reduced pressure CVD ( Chemical Vapor Deposition) method.
[0005]
Next, as shown in FIG. 25B, a contact hole CH communicating with the impurity diffusion region of the semiconductor substrate 301 and a wiring with a predetermined pattern electrically connected to the impurity diffusion region of the semiconductor substrate 301 are formed. The groove M is formed using a known photolithography technique and etching technique.
[0006]
Next, as shown in FIG. 25C, a barrier film 305 is formed in the surface of the interlayer insulating film 302, the contact hole CH, and the trench M. The barrier film 305 is formed of a material such as Ta, Ti, TaN, or TiN by a known sputtering method. In order to prevent the barrier film 305, when the material constituting the wiring is copper and the interlayer insulating film 302 is made of silicon oxide, copper has a large diffusion coefficient to silicon oxide and is easily oxidized. Provided.
[0007]
Next, as shown in FIG. 26D, copper is deposited with a predetermined film thickness on the barrier film 305 by a known sputtering method to form a seed film 306.
Next, as shown in FIG. 26E, a copper film 307 is formed so as to fill the contact hole CH and the groove M with copper. The copper film 307 is formed by, for example, a plating method, a CVD method, a sputtering method, or the like.
[0008]
Next, as shown in FIG. 26F, the excess copper film 307 and the barrier film 305 on the interlayer insulating film 302 are removed by CMP and planarized.
Through the above steps, the copper wiring 308 and the contact 309 are formed.
By repeating the above process on the wiring 308, a multilayer wiring can be formed.
[0009]
[Problems to be solved by the invention]
However, in the copper wiring formation process using the dual damascene method described above, in the process of removing the excess copper film 307 by the CMP method, the conventional planarization technique using the CMP method is performed between the polishing tool and the copper film. Since the semiconductor substrate is polished by applying a predetermined pressure to the substrate, the damage to the semiconductor substrate is large, especially when an organic insulating film with a low dielectric constant and low mechanical strength is used for the interlayer insulating film. There are problems such as generation of cracks in the interlayer insulating film and peeling of the interlayer insulating film from the semiconductor substrate.
[0010]
In addition, since the removal performance of the interlayer insulating film 302, the copper film 307, and the barrier film 305 is different, there is a problem that dishing, erosion (thinning), recess, and the like are likely to occur in the wiring 308.
As shown in FIG. 27, for example, when a wide wiring 308 such as about 100 μm exists in the design rule of the 0.18 μm rule, the dishing is excessively removed at the center of the wiring, When this dishing occurs, the cross-sectional area of the wiring 308 is insufficient, which causes a wiring resistance value defect and the like. This dishing is likely to occur when relatively soft copper or aluminum is used for the wiring material.
As shown in FIG. 28, erosion is a phenomenon in which a portion having a high pattern density, such as a wiring having a width of 1.0 μm formed in a range of 3000 μm at a density of 50%, is excessively removed. If erosion occurs, the cross-sectional area of the wiring is insufficient, which causes a wiring resistance value failure or the like.
As shown in FIG. 29, the recess is a phenomenon in which the wiring 308 is lowered at the boundary between the interlayer insulating film 302 and the wiring 308 and a step is formed. It becomes a cause of defective values.
[0011]
On the other hand, in the step of planarizing and removing the excess copper film 307 by the CMP method, it is necessary to efficiently remove the copper film. Therefore, the polishing rate as the removal amount per unit time is, for example, 500 nm / min. It is required to be the above.
In order to increase the polishing rate, it is necessary to increase the processing pressure on the wafer. When the processing pressure is increased, scratch SC and chemical damage CD are likely to occur on the wiring surface as shown in FIG. It is likely to occur with soft copper. For this reason, it becomes a cause of problems such as wiring open, short, wiring resistance value failure, etc. Also, if the processing pressure is increased, the amount of scratches, interlayer insulation film peeling, dishing, erosion and recesses will increase. There was a disadvantage.
[0012]
The present invention has been made in view of the above-mentioned problems. Therefore, the present invention can easily flatten the initial unevenness when the metal film is flattened by polishing, and can remove excess metal film. An object of the present invention is to provide a polishing apparatus that is excellent in resistance and can suppress damage to a metal film.
[0013]
[Means for Solving the Problems]
  In order to achieve the above object, a polishing apparatus of the present invention is a polishing apparatus for polishing an object to be polished having a copper film on a surface to be polished, the conductive polishing tool having a polishing surface, and the polishing tool. A polishing tool rotating and holding means for rotating and holding a workpiece about a predetermined rotation axis, and holding and rotating the object to be polished about a predetermined rotating shaft.CoveredA polishing object rotating and holding means, a movement positioning means for moving and positioning the polishing tool in a direction substantially perpendicular to the surface to be polished of the object to be polished, and a surface to be polished and a surface to be polished are predetermined. Relative movement means for relatively moving along a plane, electrolyte supply means for supplying an electrolyte containing a chelating agent on the surface to be polished, the surface to be polished as an anode and the polishing tool as a cathode, and the object to be polished Current supply means for supplying a current flowing from the surface to the polishing tool through the electrolytic solution;The current supply means is arranged so as to be in contact with or close to the surface to be polished, and applies a predetermined voltage between the anode member and the polishing tool, the anode member energizing with the surface to be polished as an anode The polishing tool has an annular shape, one end surface of the ring constitutes a polishing surface, the anode member is provided in a non-contact manner inside the ring of the polishing tool, It is rotated and held together with the polishing tool by the polishing tool rotation holding means..
[0014]
According to the above polishing apparatus of the present invention, for example, when a copper film having irregularities is formed on the surface to be polished, the surface of the copper film to be polished is anodized by the current supply means. Then, the anodized copper is chelated by the chelating agent in the electrolytic solution supplied by the electrolytic solution supplying means, and a chelate film having a very low mechanical strength that can be easily removed is formed.
By moving or positioning the polishing surface in contact with or approaching the surface to be polished, and rotating the polishing surface and the surface to be polished in contact with or in proximity to each other by the polishing tool rotation holding unit and rotation holding unit, respectively. The convex portion is removed, and further, the convex portion of the chelate film on the entire surface to be polished is polished and removed by the relative movement means, whereby the object to be polished can be efficiently polished with a low polishing pressure.
[0015]
  Also,Stable current supply can be performed by flowing current locally through the electrolytic solution through the electrolytic solution by the anode member. In this case, the surface to be polished is energized from the anode member through the electrolytic solution, and further from the surface to be polished to the polishing tool through the electrolytic solution, so that the copper film in the vicinity of the polishing tool as the cathode is anodized. And chelated.
[0016]
In the polishing apparatus of the present invention, preferably, the power source outputs a pulsed voltage having a predetermined cycle.
For example, by making the pulse width very short, the amount of chelate film produced by anodization per pulse is very small, and discharge due to a sudden change in the distance between electrodes, such as contact with surface irregularities, bubbles, particles, etc. It is effective to prevent sudden and enormous anodic oxidation of the copper film, such as spark discharge caused by a sudden change in electric resistance that occurs when the intervening metal is interposed, and to make as small as possible continuous.
[0017]
In the polishing apparatus of the present invention, preferably, the anode member is made of a noble metal as compared with copper formed on the surface to be polished. Thereby, elution to the electrolyte solution of an anode member, etc. can be prevented, and a copper film can be actively anodized. In addition, since the cathode does not elute originally, it is not necessary to consider nobility.
[0018]
In the polishing apparatus of the present invention, preferably, the current detection unit detects a value of a current flowing from the surface to be polished to the polishing tool, and the current value is constant based on a detection signal from the current detection unit. And a control means for controlling the position of the polishing tool in a direction substantially perpendicular to the surface to be polished.
By controlling the current value to be constant, the current density is always constant, and the amount of chelate film produced by anodic oxidation can also be controlled to be constant.
[0021]
  Furthermore, in order to achieve the above object, the polishing apparatus of the present invention is arranged in parallel with the holding means for holding the object to be polished and the surface to be polished.RuElectrode plate and the object to be polishedConsists of connected pulse generator, amplifier and vibratorVibration means;Does not contain abrasive grains,Electrolyte containing chelating agentWhen,A water tank for storing the electrolyte solution;An electrolytic current supply means for supplying an electrolytic current flowing from the polished surface to the electrode plate through the electrolytic solution using the polished surface as an anode and the electrode plate as a cathode;The electrolytic current supply means outputs a pulsed voltage every 20 to 50 msec, the holding means for the object to be polished and the electrode plate are disposed so as to be immersed in the electrolytic solution, and the copper film The electrolysis current supply means supplies the electrolysis current so that the chelating agent forms a chelate film by reacting with the chelating agent, and the vibration excitation means removes the convex portion of the chelate film. It vibrates the object.
[0022]
According to the above polishing apparatus of the present invention, for example, when an uneven copper film is formed on the surface to be polished of the object to be polished, the surface of the copper film of the surface to be polished is The oxidized and anodized copper is chelated by the chelating agent in the electrolytic solution supplied by the electrolytic solution supply means, and a chelate film having a very low mechanical strength that can be easily removed is formed.
The convex portion of the chelate film is selectively removed by the vibration action on the object to be polished by the vibration means, and efficient polishing with little damage to the object to be polished can be achieved.
[0025]
  Furthermore, in order to achieve the above object, a polishing apparatus of the present invention is a polishing apparatus for polishing an object to be polished having a metal film on a surface to be polished, the object to be polishedThe surface to be polishedDispel, Vents were providedWaiPing member and,A counter electrode disposed on an upper surface of the wiping member, facing the surface to be polished, and a wiping member rotation holding unit that rotates and holds the counter electrode and the wiping member around a predetermined rotation axis; The object to be polished rotating and holding means for holding the object to be polished and rotating around a predetermined rotation axis;Polishing targetOn the surfaceElectrolyte supply means for supplying an electrolyte, and the object to be polishedsurfaceCurrent supply means for supplying current between the counter electrodes;The wiping member rotating and holding means and having a through hole connected perpendicularly to the center of the counter electrode and the wiping member and having a current-carrying shaft through which the current is passed. The electrolytic solution is supplied onto the surface to be polished from the electrolytic solution supply unit through the through hole, through the wiping member..
[0026]
  Furthermore, in order to achieve the above object, the polishing apparatus of the present invention comprises:in frontPolishingsurfaceAnd said WaiPing member andRelative movement means for relative movementFurtherHave.
[0027]
  The relative moving means isin frontPolishingsurfaceTo the WaiPing memberPress the said polishedsurfaceAbove WaiPing memberMove horizontally. Alternatively, the relative movement means may be the YPing memberofOn the polished surface sideOn the surfaceSo that the surface to be polished is locatedThe object to be polishedrotationThe holding means is moved horizontally.
[0028]
According to the polishing apparatus of the present invention, for example, when a metal film is formed on the surface to be polished, the electrolytic solution is supplied onto the surface of the object to be polished by the electrolytic solution supply means, By supplying a current between the surface of the object to be polished and the counter electrode by the current supply means, the metal film on the surface to be polished is anodized and becomes an ionic state, and the mechanical strength that can be easily removed is very low. It becomes a state.
Then, by wiping the surface of the anodized metal film with a wiper, the anodized metal film is removed, so that the object to be polished can be efficiently polished with a low pressure.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0030]
First embodiment
(Manufacturing method and polishing method of semiconductor device)
As an example, a case where the embodiment of the present invention is applied to a metal wiring forming process by a dual damascene method in a semiconductor device manufacturing process will be described.
[0031]
First, as shown in FIG. 1A, an interlayer insulating film 102 made of, for example, a silicon oxide film is reacted, for example, on a semiconductor substrate 101 made of, for example, silicon in which an impurity diffusion region (not shown) is appropriately formed. It is formed by a low pressure CVD (Chemical Vapor Deposition) method using TEOS (tetraethylorthosilicate) as a source.
As the interlayer insulating film 102, a TEOS (tetraethylorthosilicate) film or silicon nitride film formed by a CVD method, a so-called Low-k (low dielectric constant film) material, or the like can be used.
Here, examples of the low dielectric constant insulating film include SiF, SiOCH, polyaryl ether, porous silica, and polyimide.
[0032]
Next, as shown in FIG. 1B, a contact hole CH and a wiring groove M leading to the impurity diffusion region of the semiconductor substrate 101 are formed using, for example, a known photolithography technique and etching technique. The depth of the wiring groove M is, for example, about 800 nm.
[0033]
Next, as shown in FIG. 1C, a barrier film 103 is formed in the surface of the interlayer insulating film 102, the contact hole CH, and the wiring groove M.
The barrier film 103 is made of, for example, Ta, Ti, W, Co, Si, Ni, and alloys such as TaN, TiN, WN, CoW, CoWP, TiSiN, and NiWP made of these metals and phosphorus or nitrogen, and the like. It is composed of laminated films. The barrier film made of these materials is formed with a film thickness of, for example, about 25 nm by a PVD (Physical Vapor Deposition) method or a CVD method using a known sputtering apparatus, vacuum vapor deposition apparatus or the like.
The barrier film 103 is provided in order to prevent the material constituting the wiring from diffusing into the interlayer insulating film 102 and to improve the adhesion with the interlayer insulating film 102. For example, when the wiring material is copper and the interlayer insulating film 102 is silicon oxide, copper has a large diffusion coefficient to silicon oxide and is likely to be oxidized, so this needs to be prevented.
[0034]
Next, as shown in FIG. 2D, a seed film 104 made of the same material as the wiring forming material is formed on the barrier film 103 by a known sputtering method to a thickness of about 150 nm, for example. The seed film 104 is formed to perform electrolytic plating later. For example, when the metal film is embedded in the wiring groove M and the contact hole CH, the seed film 104 is formed to promote the growth of the metal film.
[0035]
Next, as shown in FIG. 2E, the barrier film 103 is made of Al, W, WN, Cu, Au, Ag or the like or an alloy film thereof so as to fill the contact hole CH and the wiring groove M. The wiring layer 105 is formed with a film thickness of about 1600 nm, for example. The wiring layer 105 is preferably formed by electrolytic plating or electroless plating, but may be formed by CVD, PVD, sputtering, or the like. The seed film 104 is integrated with the wiring layer 105.
On the surface of the wiring layer 105, unevenness having a height of, for example, about 800 nm, which is generated by filling the contact hole CH and the wiring groove M, is formed.
In the following, for example, a case where copper is laminated as a wiring layer will be described.
[0036]
The above process is performed in the same manner as in the prior art. However, in the polishing method of the present invention, the removal of the excess wiring layer 105 existing on the interlayer insulating film 102 is performed by electrolytic action instead of chemical mechanical polishing. Performed by electrolytic composite polishing. Specifically, the copper film is anodized by electrolytic action to form a chelate film on the surface. The polishing in the present invention is broadly defined as a scraping function, a polishing function, a rubbing function, or a wiping function.
[0037]
As shown in FIG. 3 (f), the chelate film is formed by disposing the electrolyte member EL in which the cathode member 120 is arranged in parallel to the copper film 105, and the electrolyte and the chelate agent that chelates copper, for example, as an additive. It is interposed between the cathode member 120 and the copper film 105. In FIG. 4 and subsequent figures, descriptions of the cathode member 120 and the electrolytic solution EL are omitted.
In addition to the above, the electrolytic solution EL can contain a brightener, Cu ions, and the like as additives.
The temperature of the electrolytic solution is controlled to optimize the oxidation of the metal film surface, the chelate formation ratio, the wiping ratio, and the like.
Here, as the chelating agent, for example, quinaldic acid of chemical structural formula (1), glycine of chemical structural formula (2), citric acid of chemical structural formula (3), oxalic acid of chemical structural formula (4), chemical A propionic acid having the structural formula (5) or the like is used.
Next, a voltage is applied using the cathode member 120 as a cathode and the copper film 105 and the barrier film 103 as an anode.
[0038]
[Chemical 1]

[0039]
[Chemical formula 2]
NH₂ CH₂ COOH (2)
[0040]
[Chemical 3]

[0041]
[Formula 4]
(COOH)₂                   (4)
[0042]
[Chemical formula 5]
C₂ H_Five COOH (5)
[0043]
The copper film 105 serving as the anode is anodized to form CuO. Here, since the distance d1 between the convex portion on the surface of the copper film 105 and the cathode member 120 is shorter than the distance d2 between the concave portion on the surface of the copper film 105 and the cathode member 120, the cathode member 120 and the copper film 105 are short. When the potential difference is constant, the current density at the convex portion is larger than that at the concave portion, so that anodization is promoted.
[0044]
As shown in FIG. 3G, the surface of the anodized copper film (CuO) 105 is chelated by a chelating agent in the electrolytic solution. When quinaldic acid is used as the chelating agent, the film is made of a chelate compound of chemical structural formula (6), and when glycine is used, the film is made of a chelate compound of chemical structural formula (7). These chelate films 106 have a higher electric resistance than copper and a very low mechanical strength. Therefore, after the chelate film 106 is formed on the surface of the copper film 105, the value of current flowing from the copper film 105 to the cathode member 120 through the electrolytic solution EL decreases. Before being anodized, the chelation of copper is in a controlled state.
[0045]
[Chemical 6]

[0046]
[Chemical 7]

[0047]
Next, as shown in FIG. 4H, the convex portions of the chelate film 106 formed on the surface of the copper film 105 are selectively removed by wiping, mechanical polishing, or the like. In addition, when removing the convex part of the chelate film | membrane 106 by mechanical polishing, the slurry not shown may be previously contained in electrolyte solution EL. In addition, since the mechanical strength of the chelate film is very small, the chelate film 106 can be easily removed by applying vibration to the substrate 101 or jetting the electrolyte EL.
At this time, since the convex portion of the copper film 105 having low electrical resistance is exposed in the electrolytic solution, the value of the current flowing from the copper film 105 to the cathode member 120 through the electrolytic solution EL increases.
[0048]
Next, as shown in FIG. 4 (i), the convex portion of the copper film 105 exposed in the electrolytic solution is intensively anodized because of its low electrical resistance and its short distance from the cathode member 120. The anodized copper is chelated. At this time, the value of the current flowing from the copper film 105 to the cathode member 120 through the electrolyte EL decreases again.
Thereafter, the convex portion of the chelate film 106 is selectively removed by the above-described wiping, mechanical polishing, etc., and the exposed copper film 105 is intensively anodized and chelated, and the convex portion of the chelate film 106 is selectively selected. Repeat the removal step. At this time, the value of the current flowing from the copper film 105 to the cathode member 120 through the electrolytic solution EL increases simultaneously with the removal of the chelate film 106 and repeats a state of decreasing simultaneously with the formation of the chelate film 106.
[0049]
Next, as shown in FIG. 5J, the copper film 105 is planarized after the above-described steps. By removing the flattened copper film 105 over the entire surface by wiping, mechanical polishing or the like, the value of the current flowing from the copper film 105 to the cathode member 120 through the electrolyte EL takes a maximum value once.
[0050]
Next, as shown in FIG. 5 (k), the process of removing the generated chelate film by anodic oxidation is continued on the entire surface of the flattened copper film 105 until the excess copper film 105 on the barrier film 103 disappears.
[0051]
Next, as shown in FIG. 5L, the entire surface of the copper film 105 is removed by, for example, the wiping or mechanical polishing described above, and the surface of the barrier film 103 is exposed. At this time, since the barrier film 103 having higher electrical resistance than the copper film 105 is exposed, the current value after the chelate film 106 is removed starts to decrease. When the current value starts to decrease (near the end point), the applied voltage is reduced, and then the application of the voltage is stopped to stop the progress of chelation by anodic oxidation. By the process so far, the initial unevenness of the copper film 105 is flattened.
Thereafter, the copper film is formed by removing the barrier film 103 deposited outside the wiring trench.
[0052]
According to the polishing method according to the present embodiment, the polishing is performed with the polishing rate being assisted electrochemically, and therefore, polishing can be performed at a lower processing pressure compared to normal chemical mechanical polishing. This is very advantageous in terms of reduction of scratches, step relief performance, reduction of dishing and erosion, as compared with simple mechanical polishing.
Further, since the polishing can be performed at a low processing pressure, an organic low dielectric constant film or a porous low dielectric constant insulating film which is weak in mechanical strength and easily broken by a normal chemical mechanical polishing is used as the interlayer insulating film 102. It is very useful when used in
[0053]
When slurry containing alumina particles or the like is used in normal chemical mechanical polishing, it contributes to CMP processing and remains without being worn out or buried in the copper surface (particles). In the polishing method, even when mechanical polishing or wiping using a chelating agent that does not contain abrasive grains as an electrolyte, the chelate film formed on the surface has a very low mechanical strength and can be sufficiently removed.
Further, by monitoring the electrolytic current, the polishing process can be managed, and the progress of the polishing process can be accurately grasped.
[0054]
The polishing method according to the present invention is not limited to the above embodiment.
In addition to copper, as described above, for example, it can be applied to a wiring layer made of Al, W, WN, Cu, Au, Ag or the like or an alloy film thereof, and polishing of a barrier film made of the above-described materials or the like. It can also be applied to.
Further, the present invention can be applied to polishing various metal films used other than wirings.
Various modifications such as the type of chelating agent and the type of the cathode member can be made without departing from the gist of the present invention.
Further, the method for manufacturing a semiconductor device according to the present invention is not limited to the above embodiment.
For example, the method other than the metal film polishing method is not limited in any way, and in the present embodiment, the dual damascene method has been described as an example, but the present invention can also be applied to the single damascene method. Various changes can be made to the forming method, the forming method of the copper film, the forming method of the barrier film and the like without departing from the gist of the present invention.
[0055]
(Polishing equipment)
FIG. 6 is a diagram showing the configuration of the polishing apparatus according to the embodiment of the present invention.
The polishing apparatus shown in FIG. 6 includes a processing head unit, an electrolytic power supply 61, a controller 55 having a function of controlling the entire polishing apparatus, a slurry supply apparatus 71, and an electrolyte supply apparatus 81.
Although not shown, the polishing apparatus is installed in a clean room, and in the clean room, a loading / unloading port for loading / unloading a wafer cassette storing a wafer to be polished is provided. Further, a wafer transfer robot for transferring wafers between the wafer cassette carried into the clean room through the carry-in / out port and the polishing apparatus is installed between the carry-in / out port and the polishing apparatus. Moreover, the cleaning mechanism for cleaning the wafer after being polished by the polishing apparatus may be configured as one unit.
[0056]
The processing head unit holds the polishing tool 11 and rotates the polishing tool holding unit (polishing tool rotation holding unit) 10 and the Z-axis positioning mechanism unit (moving) for positioning the polishing tool holding unit 10 at a target position in the Z-axis direction. (Positioning means) 30 and an X-axis movement mechanism (rotation holding means and relative movement means) 40 that holds and rotates the wafer W to be polished and moves in the X-axis direction.
[0057]
The Z-axis positioning mechanism 30 is connected to a Z-axis servo motor 31 fixed to a column (not shown), a ball screw shaft 31a connected to the Z-axis servo motor 31, the holding device 13 and the main shaft motor 14, and the ball screw shaft A Z-axis slider 32 having a threaded portion that is screwed to 31a, and a guide rail 33 installed on a column (not shown) that holds the Z-axis slider 32 movably in the Z-axis direction.
[0058]
The Z-axis servomotor 31 is driven to rotate by receiving a drive current from a Z-axis driver 51 connected to the Z-axis servomotor 31. The ball screw shaft 31a is provided along the Z-axis direction, one end is connected to the Z-axis servomotor 31, and the other end is rotatably held by a holding member provided in the column (not shown). The threaded portion of the Z-axis slider 32 is screwed together.
With the above configuration, the ball screw shaft 31a is rotated by driving the Z-axis servo motor 31, and the polishing tool 11 held by the polishing tool holding unit 10 is moved to an arbitrary position in the Z-axis direction via the Z-axis slider 32. Moved and positioned. The positioning accuracy of the Z-axis positioning mechanism unit 30 is set to a resolution of about 0.1 μm, for example.
[0059]
The X-axis moving mechanism unit 40 includes a wafer table 42 that chucks the wafer W, a driving motor 44 that supplies a driving force that rotationally drives the wafer table 42, and a belt that connects the driving motor 44 and the rotating shaft of the holding device 45. 46, a processing pan 47 provided in the holding device 45, an X-axis slider 48 provided with the drive motor 44 and the holding device 45, an X-axis servo motor 49 provided on a gantry (not shown), and an X-axis servo The ball screw shaft 49a is connected to the motor 49, and the movable member 49b is connected to the X-axis slider 48 and has a threaded portion that is screwed into the ball screw shaft 49a.
[0060]
The wafer table 42 sucks the wafer W by, for example, vacuum suction means.
The processing pan 47 is provided for recovering a used electrolyte or a liquid such as a slurry.
The drive motor 44 is connected to the table driver 53 and is driven by a drive current supplied from the table driver 53. By controlling this drive current, the wafer table 42 is rotated at a predetermined rotational speed. Can do.
The X-axis servo motor 49 is connected to the X-axis driver 54, and is driven to rotate by the drive current supplied from the X-axis driver 54. The X-axis slider 48 is moved to the X-axis via the ball screw shaft 49a and the movable member 49b. Drive in the direction. At this time, the speed of the wafer table 42 in the X-axis direction can be controlled by controlling the drive current supplied to the X-axis servomotor 49.
[0061]
The slurry supply device 71 supplies the slurry onto the wafer W via a supply nozzle (not shown). As the slurry, for example, aluminum oxide (alumina), cerium oxide, silica, germanium oxide or the like is contained as abrasive grains in an oxidizing aqueous solution based on hydrogen peroxide, iron nitrate, potassium iodate, etc. Is used. In addition, what is necessary is just to supply a slurry as needed.
[0062]
The electrolytic solution supply device 81 supplies an electrolytic solution EL containing an electrolyte and an additive onto the wafer W via a supply nozzle (not shown).
As the electrolyte, one based on an organic solvent or an aqueous solution can be used.
Examples of the acid in the electrolyte include copper sulfate, ammonium sulfate, and phosphoric acid. Examples of the alkali include ethyldiamine, NaOH, and KOH.
Moreover, organic solvent dilution liquid mixture, such as methanol, ethanol, glycerol, ethylene glycol, can also be used as electrolyte.
Additives include Cu ions, brighteners or chelating agents.
As the brightener, for example, sulfur, copper ion such as copper hydroxide and copper phosphate, chlorine ion such as hydrochloric acid, benzotriazole (BTA), polyethylene glycol and the like can be used.
As the chelating agent, for example, quinoline, anthranilic acid and the like are used in addition to the above-described quinaldic acid, glycine, citric acid, oxalic acid, propionic acid and the like.
[0063]
FIG. 7 is a diagram illustrating an internal structure of the polishing tool holding unit 10 of the polishing apparatus according to the present embodiment.
The polishing tool holding unit 10 includes a polishing tool 11, a flange member 12 that holds the polishing tool 11, a holding device 13 that rotatably holds the flange member 12 via a main shaft 13a, and a main shaft that is held by the holding device 13. A spindle motor 14 that rotates 13 a and a cylinder device 15 provided on the spindle motor 14 are configured.
[0064]
The main shaft motor 14 is composed of, for example, a direct drive motor, and a rotor (not shown) of the direct drive motor is coupled to the main shaft 13a.
The spindle motor 14 has a through hole into which the piston rod 15b of the cylinder device 15 is inserted at the center. The spindle motor 14 is driven by a drive current supplied from the spindle driver 52.
[0065]
The holding device 13 includes, for example, an air bearing, and the main shaft 13a is rotatably held by the air bearing. The main shaft 13a of the holding device 13 also has a through hole into which the piston rod 15b is inserted at the center.
[0066]
The flange member 12 is made of a metal material, is connected to the main shaft 13a, has an opening 12a, and the polishing tool 11 is fixed to the lower end surface 12b.
Since the upper end surface 12c side of the flange member 12 is connected to the main shaft 13a, the flange member 12 is also rotated by the rotation of the main shaft 13a.
An upper end surface 12 c of the flange member 12 is in contact with an energizing brush 27 fixed to a conductive energizing member 28 (cathode energizing member) provided on the side surfaces of the spindle motor 14 and the holding device 13. The flange member 12 is electrically connected.
[0067]
The cylinder device 15 is fixed on the case of the spindle motor 14 and has a built-in piston 15a. The piston 15a is oriented in one of the directions of arrows A1 and A2 depending on the air pressure supplied into the cylinder device 15, for example. Driven by.
A piston rod 15b is connected to the piston 15a, and the piston rod 15b protrudes from the opening 12a of the flange member 12 through the center of the spindle motor 14 and the holding device 13.
A pressing member 21 is connected to the tip of the piston rod 15b, and the pressing member 21 is connected to the piston rod 15b by a connecting mechanism that can change the posture within a predetermined range.
The pressing member 21 can come into contact with the peripheral edge portion of the opening 22a of the insulating plate 22 disposed at the opposing position, and presses the insulating plate 22 by driving the piston rod 15b in the arrow A2 direction.
[0068]
A through hole is formed at the center of the piston rod 15b of the cylinder device 15, and the energizing shaft 20 is inserted into the through hole and fixed to the piston rod 15b.
The energizing shaft 20 is made of a conductive material, and the upper end side extends through the piston 15a of the cylinder device 15 to the rotary joint 16 provided on the cylinder device 15, and the lower end side is a piston rod 15b. And extends through the pressing member 21 to the electrode plate 23 and is connected to the electrode plate 23.
[0069]
The energizing shaft 20 has a through-hole formed in the center, and this through-hole serves as a supply nozzle that supplies an electrolytic solution containing a chemical abrasive (slurry) and a chelating agent onto the wafer W.
The energizing shaft 20 plays a role of electrically connecting the rotary joint 16 and the electrode plate 23.
[0070]
The rotary joint 16 is electrically connected to the positive electrode of the electrolytic power supply 61 and maintains energization to the energizing shaft 20 even when the energizing shaft 20 rotates.
[0071]
The electrode plate (anode member) 23 connected to the lower end portion of the current-carrying shaft 20 is made of a metal material, and in particular, is made of a metal equivalent to a metal film such as copper formed on the wafer W or a noble metal than the metal film. ing.
The upper surface side of the electrode plate 23 is held by the insulating plate 22, the outer peripheral portion of the electrode plate 23 is fitted to the insulating plate 22, and the scrub member 24 is attached to the lower surface side.
[0072]
The insulating plate 22 is made of, for example, an insulating material such as ceramics, and the insulating plate 22 is connected to the main shaft 13 a by a plurality of rod-like connecting members 26. The connecting members 26 are arranged at equal intervals from the central axis of the insulating plate 22 at a predetermined radial position, and are held movably with respect to the main shaft 13a. For this reason, the insulating plate 22 is movable in the axial direction of the main shaft 13a.
In addition, the insulating plate 22 and the main shaft 13a are connected by an elastic member 25 made of, for example, a coil spring, corresponding to each connecting member 26.
[0073]
By making the insulating plate 22 movable with respect to the main shaft 13a of the holding device 13 and connecting the insulating plate 22 and the main shaft 13a with the elastic member 25, high-pressure air is supplied to the cylinder device 15 to supply the piston rod 15b. Is lowered in the direction of arrow A2, the pressing member 21 pushes down the insulating plate 22 against the restoring force of the elastic member 25, and the scrub member 24 is also lowered.
When the supply of high-pressure air to the cylinder device 15 is stopped from this state, the insulating plate 22 is raised by the restoring force of the elastic member 25, and the scrub member 24 is also raised at the same time.
[0074]
The polishing tool 11 is fixed to the annular lower end surface 12 b of the flange member 12. The polishing tool 11 is formed in a wheel shape and includes an annular polishing surface 11a on the lower end surface. The polishing tool 11 has conductivity, and is preferably formed of a relatively soft material. For example, carbon such as binder matrix (binder) itself, or resin such as urethane resin, melamine resin, epoxy resin, polyvinyl acetal (PVA) containing conductive material such as sintered copper and metal compound It can form from the porous body which consists of.
The polishing tool 11 is directly connected to the conductive flange member 12 and is energized from an energizing brush 27 that contacts the flange member 12.
That is, the conductive energizing member 28 provided on the side surfaces of the spindle motor 14 and the holding device 13 is electrically connected to the negative pole of the electrolysis power supply 61, and the energizing brush 27 provided on the energizing member 28 is connected to the flange member 12. Thus, the polishing tool 11 is electrically connected to the electrolytic power source 61 through the energizing member 28, the energizing brush 27, and the flange member 12.
[0075]
The electrolytic power source (current supply means) 61 is a device that applies a predetermined voltage between the rotary joint 16 and the energizing member (cathode energizing member) 28 described above. By applying a voltage between the rotary joint 16 and the energizing member 28, a potential difference is generated between the polishing tool 11 and the scrub member 24.
The electrolytic power supply 61 is not a constant voltage power supply that always outputs a constant voltage, but preferably a power supply that outputs a voltage in a pulse form at a constant cycle, for example, a built-in switching regulator circuit.
Specifically, a power source that outputs a pulsed voltage at a constant period and can change the pulse width as appropriate is used. As an example, the output voltage is 2 to 5 V DC, the maximum output current is 2 to 3 A, and the pulse width can be changed to any one of 1, 2, 5, 10, 20, and 50 msec.
The reason why the pulse-like voltage output is short as described above is to make the amount of anodic oxidation per pulse very small. That is, a spark caused by a sudden change in the distance between the electrodes, such as contact with the unevenness of a metal film such as copper formed on the surface of the wafer W, or a spark caused by a sudden change in electrical resistance caused by bubbles or particles. This is effective in preventing sudden and enormous anodic oxidation of the metal film, such as electric discharge, and making it as small as possible.
In addition, since the output voltage is relatively high compared to the output current, a certain margin can be set for setting the distance between the electrodes. That is, even if the distance between the electrodes changes slightly, the change in current value is small because the output voltage is high.
The pulse to be applied is not limited to the above, and a rectangular pulse, a sine waveform, a sawtooth waveform, or a PAM waveform may be applied as a periodic pulse.
[0076]
The electrolysis power supply 61 is provided with an ammeter 62 as current detection means of the present invention. This ammeter 62 is provided for monitoring the electrolysis current flowing through the electrolysis power supply 61, and the monitored current value signal. 62s is output to the controller 55.
Further, the electrolytic power source 61 may include a resistance meter as a resistance value detecting unit instead of the current detecting unit, and the role thereof is the same as that of the current detecting unit.
[0077]
The controller 55 has a function of controlling the entire polishing apparatus. Specifically, the controller 55 outputs a control signal 52 s to the spindle driver 52 to control the number of revolutions of the polishing tool 11 and to the Z-axis driver 51. The control signal 51 s is output to control the positioning of the polishing tool 11 in the Z-axis direction, the control signal 53 s is output to the table driver 53 to control the rotation speed of the wafer W, and the X-axis driver 54 is controlled. A control signal 54s is output to control the speed of the wafer W in the X-axis direction.
In addition, the controller 55 controls the operation of the electrolytic solution supply device 81 and the slurry supply device 71, and controls the supply operation of the electrolytic solution EL and the slurry SL.
[0078]
The controller 55 can control the output voltage of the electrolytic power supply 61, the frequency of the output pulse, the width of the output pulse, and the like.
The controller 55 also receives a current value signal 62 s from an ammeter 62 of the electrolytic power supply 61. The controller 55 can control the operation of the polishing apparatus based on these current value signals 62s. Specifically, the Z-axis servomotor 31 is controlled using the current value signal 62s as a feedback signal so that the electrolytic current obtained from the current value signal 62s is constant, or the current value specified by the current value signal 62s is set. Based on this, the operation of the polishing apparatus is controlled so as to stop the polishing process.
It is possible to apply a periodic pulse set so that the current flowing through the cathode member and the metal film changes stepwise. For example, in the initial stage of removing the metal film, the current flowing through the cathode member and the metal film is A periodic pulse set so as to increase gradually is applied. As a result, it is possible to prevent the surface state of the metal film to be removed from being deteriorated by instantaneously applying a high voltage at the start of voltage application.
Further, since the current value signal 62s becomes small near the end point of the metal film removal, when the current value signal 62s becomes smaller than the predetermined threshold value compared to the predetermined threshold value, the vicinity of the end point is reached. As a result, the output pulse is controlled to be small, and then a control signal is output to the electrolytic power supply 61 so as to stop the output of the pulse.
[0079]
The control panel 56 connected to the controller 55 allows the operator to input various data, for example, to display a monitored current value signal 62s.
[0080]
Here, FIG. 8A is a bottom view showing an example of the structure of the electrode plate 23, and FIG. 8B shows the electrode plate 23, the current-carrying shaft 20, the scrub member (cleaning member) 24, and the insulating plate 22. It is sectional drawing which shows these positional relationships.
As shown in FIG. 8A, a circular opening (supply nozzle) 23a is provided at the center of the electrode plate 23, and extends radially in the radial direction of the electrode plate 23 around the opening 23a. A plurality of groove portions 23b are formed.
Further, as shown in FIG. 8B, the lower end portion of the energizing shaft 20 is fitted and fixed to the opening portion 23 a of the electrode plate 23.
[0081]
With such a configuration, the slurry and the electrolyte supplied through the supply nozzle 20a formed at the center of the energizing shaft 20 are diffused over the entire surface of the scrub member 24 through the groove 23b.
That is, when the slurry and the electrolyte are supplied to the upper surface of the scrub member 24 through the supply nozzle 20a while the electrode plate 23, the energizing shaft 20, the scrub member 24, and the insulating plate 22 are rotated, the entire upper surface of the scrub member 24 is obtained. The slurry and electrolyte solution spread.
The scrub member 24 and the supply nozzle 20a of the energizing shaft 20 correspond to specific examples of the abrasive supply means and the electrolyte supply means of the present invention.
[0082]
The scrub member 24 adhered to the lower surface of the electrode plate 23 is formed of a material that can absorb the electrolyte and the slurry and pass them from the upper surface to the lower surface. The scrub member 24 has a surface that contacts the wafer W and scrubs the wafer W. For example, a soft brush-like material or a sponge-like material is used so as not to generate scratches on the surface of the wafer W. It is formed from a porous material or the like. For example, the porous body which consists of resin, such as a urethane resin, a melamine resin, an epoxy resin, and polyvinyl acetal (PVA), is mentioned.
[0083]
FIG. 9 shows the positional relationship between the polishing tool 11 and the wafer during polishing.
The central axis of the polishing tool 11 is inclined at a minute angle with respect to the wafer W, for example. Further, the main shaft 13a of the holding device 13 is also inclined with respect to the main surface of the wafer W in the same manner as the inclination of the polishing surface 11a. For example, a minute inclination of the main shaft 13a can be created by adjusting the mounting posture of the holding device 13 to the Z-axis slider 32.
[0084]
Thus, when the central axis of the polishing tool 11 is inclined at a minute angle with respect to the main surface of the wafer W, the polishing surface 11a of the polishing tool 11 is pressed against the wafer W with a predetermined processing pressure F. The effective contact area is kept constant.
In the polishing apparatus according to the present embodiment, a part of the polishing tool 11 is partially used as the polishing surface 11a to act on the surface of the wafer W, and the effective contact area is uniformly scanned on the surface of the wafer W to thereby adjust the wafer W. Polish the entire surface uniformly.
Thereby, if the value of the electrolysis current is controlled to be constant, the current density can always be constant, and the amount of chelation by anodic oxidation of the metal film can always be constant.
[0085]
Next, the polishing operation (polishing method) by the above-described polishing apparatus will be described by taking as an example a case where a copper film is polished as a metal film formed on the surface of the wafer W, for example. FIG. 10 is a schematic view showing a state in which the polishing tool 11 is lowered in the Z-axis direction and brought into contact with the surface of the wafer W in the polishing apparatus.
First, the wafer W is chucked on the wafer table 42, and the wafer table 42 is driven to rotate the wafer W at a predetermined number of rotations.
Further, the wafer table 42 is moved in the X-axis direction, the polishing tool 11 attached to the flange member 12 is disposed at a predetermined location above the wafer W, and the polishing tool 11 is rotated at a predetermined rotation speed. When the polishing tool 11 is rotated, the insulating plate 22, the electrode plate 23 and the scrub member 24 connected to the flange member 12 are also driven to rotate. In addition, the pressing member 21 that presses the scrub member 24, the piston rod 15b, the piston 15a, and the energizing shaft 20 rotate simultaneously.
[0086]
In this state, when the slurry SL and the electrolyte EL are supplied from the slurry supply device 71 and the electrolyte supply device 81 to the supply nozzle 20a in the energizing shaft 20, respectively, the slurry SL and the electrolyte EL are supplied from the entire surface of the scrub member 24. The
The polishing tool 11 is lowered in the Z-axis direction to bring the polishing surface 11a of the polishing tool 11 into contact with the surface of the wafer W and pressed with a predetermined processing pressure.
In addition, the electrolytic power supply 61 is activated, a negative potential is applied to the polishing tool 11 through the energizing brush 27, and a positive potential is applied to the electrode plate 23 and the scrub member 24 through the rotary joint 16.
[0087]
Further, high pressure air is supplied to the cylinder device 15 to lower the piston rod 15b in the direction of the arrow A2 in FIG. 7 and move the lower surface of the scrub member 24 to a position where it contacts or approaches the wafer W.
From this state, the wafer table 42 is moved in the X-axis direction with a predetermined speed pattern, and the entire surface of the wafer W is polished uniformly.
[0088]
11 is an enlarged view in a circle C in FIG. 10, and FIG. 12 is an enlarged view in a circle D in FIG.
As shown in FIG. 11, the scrub member 24 energizes the copper film MT formed on the wafer W as an anode through the electrolytic solution EL or by direct contact, and the polishing tool 11 is also formed on the wafer W. The copper film MT is energized as a cathode through the electrolytic solution EL or by direct contact. As shown in FIG. 11, there is a gap δ between the copper film MT and the scrub member 24._b Is present. Furthermore, as shown in FIG. 12, there is a gap δ between the copper film MT and the polishing surface 11a of the polishing tool 11._w Is present.
As shown in FIG. 11, the insulating plate 22 is interposed between the polishing tool 11 and the scrub member 24 (electrode plate 23), but the resistance R 0 of the insulating plate 22 is very large, and therefore the scrub member 24. Current i flowing through the insulating plate 22 to the polishing tool 11₀ Is almost zero, and no current flows from the scrub member 24 through the insulating plate 22 to the polishing tool 11.
[0089]
For this reason, the current i that flows from the scrub member 24 to the polishing tool 11 is the current i that flows directly to the polishing tool 11 via the resistor R1 in the electrolyte EL.₁ And the current i flowing in the current flowing from the electrolytic solution EL to the polishing tool 11 through the electrolytic solution EL again through the copper film MT formed on the surface of the wafer W.₂ Branch to
The current i is applied to the surface of the copper film MT.₂ , The copper constituting the copper film MT is anodized by the electrolytic action of the electrolytic solution EL and chelated by the chelating agent in the electrolytic solution.
[0090]
Here, the resistance R1 in the electrolyte EL becomes extremely large in proportion to the distance d between the scrub member 24 as the anode and the polishing tool 11 as the cathode. For this reason, the inter-electrode distance d is set to the gap δ_b And gap δ_w Current i flowing through the polishing tool 11 directly through the resistor R1 in the electrolyte EL.₁ Becomes very small and the current i₂ As a result, the electrolytic current mostly passes through the surface of the copper film MT. For this reason, chelation by anodic oxidation of copper constituting the copper film MT can be performed efficiently.
Also, the current i₂ Is the gap δ_b And gap δ_w As described above, the position of the polishing tool 11 in the Z-axis direction is controlled by the controller 55 as described above, so that the gap δ_b And gap δ_w By adjusting the magnitude of the current i₂ Can be made constant. Gap δ_w Is adjusted to the electrolytic current obtained from the current value signal 62s, that is, the current i.₂ Can be made constant by controlling the Z-axis servomotor 31 using the current value signal 62s as a feedback signal.
Further, the positioning accuracy of the polishing apparatus in the Z-axis direction is sufficiently high with a resolution of 0.1 μm. In addition, the effective contact area is obtained by inclining the main shaft 13a at a minute angle with respect to the main surface of the wafer W. Since it is always kept constant, if the value of the electrolysis current is controlled to be constant, the current density can always be kept constant, and the amount of chelation by anodic oxidation of the copper film can always be kept constant.
[0091]
As described above, the polishing apparatus having the above configuration has an electrolytic polishing function for generating and removing a chelate film by anodization on the surface of the copper film MT formed on the wafer W described above.
Further, in addition to the electrolytic polishing function, the polishing apparatus having the above configuration also has a chemical mechanical polishing function of a normal CMP apparatus using the polishing tool 11 and the slurry SL, and the wafer W is subjected to these electrolytic polishing function and chemical mechanical polishing function. Polishing can be performed by a composite action (hereinafter referred to as electrolytic composite polishing).
Moreover, the polishing apparatus having the above-described configuration can also perform polishing by a combined action of mechanical polishing of the polishing surface 11a of the polishing tool 11 and an electrolytic polishing function without using the slurry SL.
[0092]
According to the polishing apparatus according to the present embodiment, a metal film such as copper can be polished by the combined action of electrolytic polishing and chemical mechanical polishing, which is far more than a polishing apparatus using only chemical mechanical polishing or only mechanical polishing. In addition, the metal film can be removed with high efficiency. Since a high polishing rate for the metal film can be obtained, the processing pressure F for the wafer W of the polishing tool 11 can be reduced as compared with a polishing apparatus using only chemical mechanical polishing or only mechanical polishing, and dishing and erosion can be suppressed. Occurrence can be suppressed.
[0093]
In addition, when a slurry containing alumina particles or the like is used in a slurry used for normal chemical mechanical polishing, the slurry may remain on the metal film surface or be buried after polishing without being worn. In the polishing apparatus according to the embodiment, even when only mechanical polishing using an electrolytic solution containing a chelating agent that does not contain abrasive grains, the chelate film remaining on the surface is very low in mechanical strength and can be removed sufficiently. Therefore, it is possible to prevent particles and slurry from remaining on the wafer surface.
[0094]
Further, the positioning accuracy in the Z-axis direction of the polishing apparatus is sufficiently high as a resolution of 0.1 μm. In addition, the effective contact area is obtained by inclining the main shaft 13a with respect to the main surface of the wafer W at a minute angle. Since it is always kept constant, if the value of the electrolysis current is controlled to be constant, the current density can always be constant, and the amount of chelation by anodic oxidation of the metal film can always be constant.
In the embodiment described above, the absolute value of the polishing amount of the metal film can be controlled by the integrated amount of the electrolytic current and the time for passing the wafer W of the polishing tool 11.
[0095]
Modification 1
FIG. 13 is a schematic view showing a modification of the polishing apparatus according to the present invention.
In the polishing apparatus according to the above-described embodiment, the surface of the wafer W is energized by the conductive polishing tool 11 and the electrode plate 23 provided with the scrub member 24.
As shown in FIG. 13, the wheel-like polishing tool 311 is made conductive as in the case of the above-described polishing apparatus, and the wafer table 342 for chucking and rotating the wafer W is also made conductive. It is good. Power supply to the polishing tool 311 is performed with the same configuration as in the above-described embodiment.
In this case, energization of the wafer table 342 is performed by providing a rotary joint 316 below the wafer table 342 so that the energization of the wafer table 342 rotated by the rotary joint 316 is always maintained. Supply can be made.
[0096]
Modification 2
FIG. 14 is a schematic view showing another modification of the polishing apparatus according to the present invention.
A wafer table 442 for chucking and rotating the wafer W holds the wafer W by a retainer ring 410 provided around the wafer W.
The polishing tool 411 is made conductive, and the retainer ring 410 is also made conductive, and the polishing tool 411 is fed with the same configuration as in the above-described embodiment.
In addition, the retainer ring 410 covers and energizes the barrier layer portion formed on the wafer W. Further, power is supplied to the retainer ring 410 through a rotary joint 416 provided under the wafer table 442.
Even when the polishing tool 411 comes into contact with the wafer W, the polishing tool 411 and the polishing tool 411 are inclined by increasing the inclination amount so that a gap larger than the thickness of the retainer ring 410 can be maintained at the edge portion. Interference with the retainer ring 410 can be prevented.
[0097]
Modification 3
FIG. 15 is a schematic configuration diagram showing another embodiment of the polishing apparatus according to the present invention.
The polishing apparatus shown in FIG. 15 is obtained by adding the electrolytic polishing function of the present invention to a conventional CMP apparatus, and is a polishing surface of a polishing tool in which a polishing pad (polishing cloth) 202 is bonded on a surface plate 201. The polishing apparatus flattenes the surface of the wafer W by bringing the entire surface of the wafer W chucked by the wafer chuck 207 into contact therewith while rotating.
[0098]
On the polishing pad 202, anode electrodes 204 and cathode electrodes 203 are alternately arranged radially. The anode electrode 204 and the cathode electrode 203 are electrically insulated by an insulator 206, and the anode electrode 204 and the cathode electrode 203 are energized from the surface plate 201 side. The polishing pad 202 is constituted by the anode electrode 204, the cathode electrode 203, and the insulator 206.
The wafer chuck 207 is made of an insulating material.
Further, this polishing apparatus is provided with a supply unit 208 for supplying the electrolytic solution EL and the slurry SL to the surface of the polishing pad 202, and the electrolytic composite polishing combined with the electrolytic polishing and the chemical mechanical polishing becomes possible. Yes.
[0099]
Here, FIG. 16 is a diagram for explaining an electrolytic composite polishing operation (polishing method) by the polishing apparatus having the above-described configuration. It is assumed that a metal film 210 such as copper is formed on the surface of the wafer W.
As shown in FIG. 16, during electrolytic composite polishing, the anode EL is in a state where an electrolytic solution EL and a slurry SL are interposed between the metal film 210 formed on the surface of the wafer W and the polishing surface of the polishing pad 202. A voltage is applied between the electrode 204 and the cathode electrode 203, and the current i flows from the anode electrode 204 through the electrolyte EL through the metal 210 and again flows through the electrolyte EL to the cathode electrode 203.
At this time, in the vicinity of the circle G shown in FIG. 16, the surface of the metal film 210 generates a chelate film by anodic oxidation, and the chelate film is removed by the mechanical removal action by the polishing pad 202 and the slurry SL. Thus, planarization of the metal film is achieved.
[0100]
By adopting such a configuration, the same effects as those of the polishing apparatus according to the above-described embodiment can be obtained.
The arrangement of the anode electrode and the cathode electrode provided on the polishing pad is not limited to the configuration shown in FIG. 15. For example, as shown in FIG. 17, a plurality of linear anode electrodes 222 are arranged at equal intervals vertically and horizontally. Alternatively, the cathode electrode 223 may be disposed in each rectangular region surrounded by the anode electrode 222, and the anode pad 222 and the cathode electrode 223 may be electrically insulated by the insulator 224.
Further, for example, as shown in FIG. 18, annular anode electrodes 242 having different radii are arranged concentrically, cathode electrodes 243 are arranged in annular regions formed between the anode electrodes 242, and anode electrodes 242 are arranged. The polishing pad 241 may be electrically insulated from the cathode electrode 243 by an insulator 244.
[0101]
  Reference embodiment
  FIG. 19 illustrates the present invention.reference1 is a schematic configuration diagram of a polishing apparatus according to an embodiment. The polishing apparatus according to this embodiment includes a water tank 501 filled with a predetermined amount of electrolyte EL, a wafer holding means 530 and an electrode plate 510 disposed in the electrolyte EL of the water tank, and a pipe 522 containing the electrolyte EL of the water tank. A jet pump 520 (flowing means) sucked up by the pipe 521 and fed as a jet flow, a power source 561 (electrolytic current supply means) for applying a voltage with the electrode plate 510 as a cathode and a wafer as an anode, an ammeter 562, a controller 555 The control panel 556 is configured.
[0102]
The holding means 530 is fixed to a conductive first holding member 531 and a conductive second holding member 532 that fix the wafer, a column (not shown), and the like, and the first holding member and the second holding member are placed at predetermined positions. Z-axis positioning mechanism 533 fixed to The second holding member located on the lower side of the wafer has a circular opening 532a.
[0103]
The electrode plate 510 is disposed in parallel with the wafer in the electrolytic solution EL, and is made of, for example, oxygen-free copper.
[0104]
As the electrolytic solution EL, the same one as in the first embodiment can be used. For example, the electrolytic solution EL includes a chelating agent that chelates a metal such as copper, and may include other additives. For example, copper sulfate is used as the electrolyte to reduce the voltage applied between the wafer and the electrode plate 510.
[0105]
The electrolytic power supply (electrolytic current supply means) 561 is preferably not a constant voltage power supply that always outputs a constant voltage, but preferably a power supply that outputs the voltage in pulses at a constant cycle. For example, the voltage applied by the electrolytic power source 561 is a rectangular pulse voltage (for example, 2 to 5 V, current 2.2 A) that repeats a high voltage and a low voltage every 20 to 50 msec.
[0106]
As the pulse voltage, a voltage and a pulse width that can remove metal most efficiently can be selected according to the distance d between the wafer and the electrode plate 510.
If the distance d between the electrode plate 510 and the wafer is too small, the flowing action of the electrolyte solution interposed between the electrode plate 510 and the wafer does not function sufficiently. Therefore, the distance d preferably takes a predetermined value or more. It is preferable to set it together with the above voltage.
[0107]
The electrolysis power supply 561 is provided with an ammeter 562 as current detection means of the present invention. The ammeter 562 is provided for monitoring the electrolysis current flowing through the electrolysis power supply 561, and the monitored current value signal. 562s is output to the controller 555.
In addition, the controller 555 receives a current value signal 562 s from the ammeter 562 of the electrolytic power supply 561. The controller 555 can control the operation of the polishing apparatus based on these current value signals 562s. Specifically, the operation of the polishing apparatus is controlled to stop the polishing process based on the current value specified by the current value signal 562s.
[0108]
A control panel 556 connected to the controller 555 allows the operator to input various data, for example, to display a monitored current value signal 562s.
[0109]
Also by the configuration of the above polishing apparatus, as in the polishing apparatus according to the first embodiment, for example, when a metal film having irregularities is formed on the surface of the wafer W, by applying the wafer W as an anode, Since the metal film surface of the wafer W is anodized and the anodized metal film is chelated by the chelating agent in the electrolyte EL, and the chelate has very low mechanical strength, the pipe 521 of the jet pump 520 is used. By removing the convex portion of the chelate film by the fluid action of the electrolyte solution from the metal plate, the metal film can be flattened and removed.
Further, by monitoring the electrolytic current, the polishing process can be managed, and the progress of the polishing process can be accurately grasped.
[0110]
According to the polishing apparatus of this embodiment, the removal of the metal film can be achieved by removing the chelate film having a very low mechanical strength. Therefore, the conventional polishing apparatus using only chemical mechanical polishing or only mechanical polishing. Compared with this, the metal film can be removed much more efficiently.
Since strong pressing as in conventional mechanical polishing is not required, damage to the interlayer insulating film under the wiring metal film can be kept low, and the occurrence of dishing, erosion, and the like can be suppressed. Since a high pressure is not applied to the insulating film under the wiring metal film, the insulating film material can be applied to a low dielectric constant material whose mechanical strength is lower than that of silicon oxide using TEOS or the like as a raw material.
Moreover, since the apparatus configuration is simple as a polishing apparatus, it is possible to easily realize downsizing, easy maintenance, and improvement in operating rate.
[0111]
Furthermore, in a slurry used for normal chemical mechanical polishing, when a slurry containing alumina particles or the like is used, the slurry does not wear out after polishing and may remain on the metal surface or be buried. Such a polishing apparatus does not have such a problem.
[0112]
The present invention is not limited to the above embodiment. For example, various modifications are possible without departing from the scope of the present invention, such as the configuration of the jet pump, the type of electrode plate, and the configuration of the apparatus for holding the wafer in the water tank.
[0113]
  Second embodiment
  FIG. 20 shows the first aspect of the present invention.21 is a schematic configuration diagram of a polishing apparatus according to an embodiment. In the polishing apparatus according to the present embodiment, a vibration unit including a pulse generator 640, an amplifier 641, and a vibrator 643, a water tank 601 filled with a predetermined amount of the electrolytic solution EL, and the electrolytic solution EL of the water tank are disposed. Wafer holding means 630, electrode plate 610, electrode plate 610 as a cathode, wafer as an anode, power supply 661 (electrolytic current supply means) for applying voltage, ammeter 662, controller 655 and control panel 656. Yes.
[0114]
The holding means 630 includes a first holding member 631 that holds the electrode plate 610 in parallel with the wafer W, a second holding member 632 and a third holding member 634 that are fixed by pressure bonding with the wafer interposed therebetween, and one end of the holding means 630 is second. The fourth holding member 633 is attached to the holding member 632 and the other end is attached to the vibrator 643.
[0115]
The second holding member 632 is made of a conductive material, and also serves to energize the wafer W as an anode. The second holding member 632 has an opening portion 632 a for opening the surface of the wafer with respect to the electrode plate 610.
[0116]
As the electrolytic solution EL, the same one as in the first embodiment can be used. For example, the electrolytic solution EL includes a chelating agent that chelates a metal such as copper, and may include other additives. For example, copper sulfate is used as the electrolyte to reduce the voltage applied between the wafer and the electrode plate 510.
[0117]
The electrode plate 610 is disposed in parallel with the wafer in the electrolytic solution EL, and is made of, for example, oxygen-free copper.
[0118]
The electrolytic power source (electrolytic current supply means) 661 is preferably a power source that outputs a voltage in a pulse form at a constant cycle, instead of a constant voltage power source that always outputs a constant voltage. For example, the voltage applied by the electrolytic power source 661 is a rectangular pulse voltage (for example, 2 to 5 V, current 2.2 A) that repeats a high voltage and a low voltage every 20 to 50 msec.
[0119]
As the pulse voltage, a voltage and a pulse width that can most efficiently remove the metal film can be selected depending on the distance d between the wafer and the electrode plate 610 or the like.
If the distance d between the electrode plate 610 and the wafer is too small, the circulating action of the electrolyte solution interposed between the electrode plate 610 and the wafer does not function sufficiently. Therefore, the distance d preferably takes a predetermined value or more. It is preferable to set it together with the above voltage.
[0120]
The electrolysis power supply 661 is provided with an ammeter 662 as current detection means of the present invention. This ammeter 662 is provided for monitoring the electrolysis current flowing through the electrolysis power supply 661, and the monitored current value signal. 662s is output to the controller 655. Further, the controller 655 receives a current value signal 662 s from the ammeter 662 of the electrolytic power supply 661. The controller 655 can control the operation of the polishing apparatus based on these current value signals 662s. Specifically, the operation of the polishing apparatus is controlled to stop the polishing process based on the current value specified by the current value signal 662s.
[0121]
A control panel 656 connected to the controller 655 allows the operator to input various data, for example, to display a monitored current value signal 662s.
[0122]
Also by the configuration of the above polishing apparatus, as in the polishing apparatus according to the first embodiment, for example, when a metal film having irregularities is formed on the surface of the wafer W, by applying the wafer W as an anode, Since the metal film surface of the wafer W is anodized, the anodized metal film is chelated by the chelating agent in the electrolyte EL, and the chelate has a very low mechanical strength. By removing the convex portions of the chelate film by the wafer vibrating means, the metal film can be planarized and removed.
Further, by monitoring the electrolytic current, the polishing process can be managed, and the progress of the polishing process can be accurately grasped.
[0123]
According to the polishing apparatus of this embodiment, the removal of the metal film can be achieved by removing the chelate film having a very low mechanical strength. Therefore, the conventional polishing apparatus using only chemical mechanical polishing or only mechanical polishing. Compared with this, the metal film can be removed much more efficiently.
Since strong pressing as in conventional mechanical polishing is not required, damage to the interlayer insulating film under the wiring metal film can be kept low, and the occurrence of dishing, erosion, and the like can be suppressed. Since a high pressure is not applied to the insulating film under the wiring metal film, the insulating film material can be applied to a low dielectric constant material whose mechanical strength is lower than that of silicon oxide using TEOS or the like as a raw material.
Moreover, since the apparatus configuration is simple as a polishing apparatus, it is possible to easily realize downsizing, easy maintenance, and improvement in operating rate.
[0124]
Furthermore, in a slurry used for normal chemical mechanical polishing, when a slurry containing alumina particles or the like is used, the slurry does not wear out after polishing and may remain on the metal surface or be buried. Such a polishing apparatus does not have such a problem.
[0125]
The present invention is not limited to the above embodiment. For example, various modifications can be made without departing from the scope of the present invention, such as the configuration of the vibrator and the amplifier, the type of the electrode plate, and the configuration of the apparatus for holding the wafer in the water tank.
[0126]
  Third embodiment
  FIG. 21 shows a configuration diagram of a main part of the polishing apparatus according to the present embodiment. The basic configuration is the same as that of the first embodiment, but in this embodiment, the metal film on the wafer is removed by the wiping member 24a without using a polishing tool. Therefore, only the configuration different from the first embodiment will be described for the sake of simplicity.
[0127]
The wiping member 24a is made of, for example, an insulating material through which electricity or ions do not pass and has a pore portion therein, and is made of a material capable of energizing the wafer via the electrolytic solution EL contained in the pore portion. ing.
The above material needs to be a material that is not affected by the electrolytic solution EL.
Further, since the wiping member 24a is pressed against the surface of the wafer W and the wiping member 24a to remove the metal film on the surface of the wafer W, the wiping member needs to have a predetermined strength.
For example, the pressure for wiping only the convex portion of the metal film on the wafer surface W is about 20 to 100 g / cm.² In addition, it is necessary to have a hardness that can withstand elasticity even in the case of, and has a softness that does not cause scratches or scratches.
[0128]
As a material that satisfies the above conditions, an elastoplastic material can be used, for example, polyvinyl acetal (PVA), foamed urethane, Teflon foamed body, Teflon fiber nonwoven fabric, or the like.
Further, it may have conductivity, and a relatively soft material such as carbon having a conductive binder matrix (binder) itself, or a conductive material such as sintered copper, metal compound, etc. A porous body made of a resin such as urethane resin, melamine resin, epoxy resin, or polyvinyl acetal (PVA) can also be used.
[0129]
The electrode plate 23 is made of a metal that is nobler than the metal film formed on the surface of the wafer W, and is arranged parallel to the surface of the wafer W. For example, the electrolytic action of the metal film on the surface of the wafer W It is preferable to provide a vent hole for removing the gas generated from the surface to be polished. This vent hole is provided in order to prevent disadvantages such as non-uniformity of electrolysis between the electrode plate 23 and the wafer W due to gas.
Similarly to the first embodiment, the electrode plate 23 can be driven to rotate together with the wiping member 24a. As a result, the gas generated from the surface to be polished by the electrolytic action by rotating the electrode plate 23 causes the wafer W and the electrode to generate gas. It is possible to pull out from between the plates 23.
Further, the electrode plate 23 may have a configuration in which the electrodes are divided into regions as described with reference to FIGS. 17 and 18, thereby performing the electrolytic action on the surface to be polished partially. You can also.
[0130]
As in the first embodiment, the electrolytic power source 61 applies the predetermined pulse described above between the rotary joint 16 and the energizing brush 710 that contacts the wafer.
Here, in this embodiment, the voltage application direction is reversed, and accordingly, the voltage is applied so that the energizing brush 710 serves as an anode and the electrode plate 23 serves as a cathode. As described above, in addition to the configuration in which the voltage is applied by contacting the metal film on the surface of the wafer W with the energizing brush 710, the voltage may be applied with an electrode accessible to the metal film on the surface of the wafer W.
Specifically, as in the first embodiment, there is no particular limitation as long as it is a power source that outputs a pulsed voltage at a constant cycle and can appropriately change the pulse width. For example, a PR (Periodic Reverse) pulse voltage that repeats plus and minus at a predetermined cycle centering on 0 V is applied. As this PR pulse voltage, for example, a positive voltage with an output voltage of about 0.8 to 1.2 V and a reverse voltage of about −0.8 to −1.2 V are repeated, and the current density is 10 mA / cm.² Back flow is 10 mA / cm² The pulse width is about 20 to 50 msec for the forward flow pulse and about 5 to 10 msec for the reverse flow pulse.
Note that the pulse to be applied is not limited to the above, as in the first embodiment.
[0131]
The energizing brush 710 is made of a metal that is nobler than the metal film formed on the surface of the wafer W, and contacts the wafer surface to guide the voltage from the electrolytic power supply 61 to the wafer W. Therefore, the current supplied from the electrolytic power supply 61 flows from the current-carrying brush 710 on the wafer surface to the electrode plate 22 through the metal film surface of the wafer W and the electrolytic solution.
[0132]
The operation of the above polishing apparatus will be described.
First, the wafer W is chucked on the wafer table 42, and the wafer table 42 is driven to rotate the wafer W at a predetermined number of rotations.
Further, the wafer table 42 is moved in the X-axis direction, the wiping member 24a is disposed at a predetermined location above the wafer W, and the wiping member 24a is rotated at a predetermined rotational speed. For example, the wiping member is rotated at 100 rpm.
[0133]
From this state, when the electrolyte solution EL is supplied from the electrolyte solution supply device 81 to the supply nozzle 20a in the energizing shaft 20, the electrolyte solution EL is supplied from the entire surface of the wiping member 24a.
Further, the electrolytic power supply 61 is activated, a positive potential is applied to the metal film on the wafer surface through the energizing brush 27, and a negative potential is applied to the electrode plate 23 through the rotary joint 16.
[0134]
As a result, a positive potential is directly applied to the metal film on the wafer surface through the energizing brush 27, and a current flows to the electrode plate 22 through the electrolytic solution.
Therefore, the metal film under the wiping member 24a can be energized as an anode through the electrolytic solution, and the metal film is anodized by the electrolytic action of the electrolytic solution and chelated by the chelating agent in the electrolytic solution.
[0135]
In the above state, high pressure air is supplied to the cylinder device 15 to lower the piston rod 15b in the direction of the arrow A2 in FIG. 7, the lower surface of the wiping member 24a is brought into contact with the surface of the wafer W, and at a predetermined processing pressure. Press.
From this state, the wafer table 42 is moved in the X-axis direction with a predetermined speed pattern, and the entire surface of the wafer W is wiped uniformly.
[0136]
As described above, the polishing apparatus having the above configuration can generate and remove a chelate film by anodization on the surface of the metal film formed on the wafer W described above.
[0137]
According to the polishing apparatus according to the present embodiment, the same effects as those of the polishing apparatus according to the first embodiment can be obtained.
Furthermore, in the polishing apparatus according to the present embodiment, the level difference of the metal film on the wafer surface can be alleviated only by wiping with the wiping member 24a without using a polishing tool. It can be further reduced.
[0138]
In the present embodiment, an example in which the wiping member is rotated is shown as the wiping method. However, it is only necessary that the wiping member can be moved relative to the wafer W. It is also possible to move it horizontally. In the case of wiping by this horizontal movement, the horizontal movement speed is preferably about 15 m / min or less in order to prevent the electrolyte from scattering.
In order to promote anodic oxidation, the temperature of the electrolytic solution is preferably adjusted to about 80 ° C. or less.
It is also possible to supply an electrolytic solution to the surface of the object to be polished and hold the electrolytic solution with surface tension.
Furthermore, as an example of the object to be polished, there is no particular limitation as described above.
[0139]
  The polishing apparatus according to the present invention is not limited to the above-described embodiment. For example, as described above, as an example of an object to be polished, in addition to a copper film, in addition to aluminum, tungsten, gold, silver, and the like, they are widely applied to metal films such as alloys thereof, nitrides and oxides of the alloys, and the like. be able to. Further, these metal films are not limited to uses such as wiring and contacts. In the present embodiment, the first and first3In the embodiment, the wiping member 24a and the polishing tool 11 are wiped and polished by rotating the wafer W on the wafer W. However, the wiping member 24a and the polishing tool 11 may be moved relative to the wafer W, for example, A configuration may be adopted in which the wiping member 24a and the polishing tool 11 are pressed against the surface of the wafer W to move horizontally on the surface of the wafer W. Furthermore, various changes can be made without departing from the scope of the present invention, such as a method for energizing the wafer.
[0140]
【Example】
Embodiments using the polishing apparatus of the present invention will be described below with reference to the drawings.
[0141]
  First embodiment
  FIG. 22 shows the first of the present invention.2The removal amount per unit time of the copper film when the copper film on the surface of the wafer W is removed by chelation by anodic oxidation using the polishing apparatus according to the embodiment, and the first aspect of the present invention.2In the polishing apparatus according to the embodiment, hydrogen peroxide (H) is used as an oxidizing agent for the copper film on the surface of the wafer W in the electrolyte EL without applying a voltage to the wafer W.₂ O₂ ) Is added at a predetermined concentration, and the removal amount per unit time of the copper film when the copper film on the surface of the wafer W is removed by chelation by oxidation is compared.
[0142]
  In FIG. 22, copper is oxidized by adding an oxidant without applying a voltage, and after chelation, (A) is removed, and a quinaldic acid solution is used as the electrolyte, and H₂ O₂ The removal amount (removal rate) of the copper film per unit time at concentrations of 0%, 4.5%, 8%, and 10.7% was measured. The amount of the electrolytic solution was 150 ml. In addition, the first of the present invention2The copper film removed using the polishing apparatus according to the embodiment is (B), 150 ml of quinaldic acid solution is used as the electrolytic solution EL, hydrogen peroxide is not included, and the electrolytic solution EL is applied to the electrode plate 610 and the wafer W. Then, the removal amount (removal rate) of the copper film per unit time when a voltage was applied so that a current of 2.2 A would flow was measured.
[0143]
When hydrogen peroxide is used as the oxidizing agent, Cu is oxidized to form a copper hydrate ion ([Cu (OH)_Four ]^2-) Is formed. The copper hydrate ion is chelated by the chelating agent in the electrolyte EL. For example, when the chelating agent is quinaldic acid, a chelate of the chemical structural formula (6) is generated, and when the chelating agent is glycine. A chelate of chemical structural formula (7) is produced.
[0144]
As other experimental conditions, a wafer of 8 inches was used, the barrier metal was Ta with a thickness of 25 nm, the interlayer insulating film was a TEOS (tetraethylorthosilicate) film with a thickness of 1200 nm, and the copper was used. The film thickness was 1600 nm.
[0145]
In FIG. 22, as the amount of hydrogen peroxide as the oxidant increases, the amount of chelate film produced by oxidation of the copper film increases, so the amount of copper film removed per unit time increases. As can be seen, when the polishing method by the polishing apparatus according to the third embodiment of the present invention is used, only the chelate is generated by the anodic oxidation of copper by energization without adding hydrogen peroxide, and it depends on the oxidizing agent. It can be seen that the removal rate is dramatically improved.
[0146]
  Second embodiment
  FIG. 23 shows a first embodiment of the present invention applied to a wafer W having a copper film on the surface.2Using the polishing apparatus according to the embodiment, with the copper film as an anode, the chelate film was removed every time a current of 2.2 A was passed for 30 seconds, and the film thickness of Cu after the removal of the chelate film was measured. The measurement portion was measured for a 21-point portion when an 8-inch wafer was divided in the diameter direction from 1 point to 21 points. The points 1 and 21 were each 6 mm from the edge of the wafer. Note that quinaldic acid is used as the electrolytic solution, the Cu film has a thickness of 2000 nm, the barrier metal uses Ta with a film thickness of 25 nm, and the interlayer insulating film under the barrier metal has a TEOS film with a film thickness of 1200 nm. It was used.
[0147]
In FIG. 23, 0, 1, 2, 3, 4, and 5 on the horizontal axis each represent the number of times a current of 2.2 A is applied for 30 seconds. Therefore, the current of 2.2A respectively, 0 is not energized, 1 is 30 seconds, 2 is total 60 seconds, 3 is total 90 seconds, 4 is total 120 seconds, 5 is total 150 seconds Indicates that power was supplied.
The vertical axis indicates the film thickness (nm) of copper remaining on the wafer surface after copper is removed after energization.
In addition, the said measurement was performed in multiple times on the same conditions.
[0148]
From the measurement results, it can be seen that the thickness of the Cu film after removal decreases in proportion to the energization time each time the current is applied for a predetermined time. The average removal amount was 202.68 nm / min.
[0149]
Third embodiment
FIG. 24 shows the same result as FIG. 23 at each point of the wafer divided from 1 point to 21 points in the diameter direction.
The energization amount and energization time were the same as in the second example, and the film thickness of the Cu film after removal at each time point when the current of 2.2 A was energized for 30 seconds was repeated several times. It is.
Other conditions such as the used wafer and the type of electrolytic solution are the same as in the second embodiment.
[0150]
In FIG. 24, points 1 to 21 on the horizontal axis indicate positions on the wafer described above, and the vertical axis indicates the film thickness (nm) of copper after removal.
2.2A current for 0 seconds (before energization), B for 30 seconds, C for a total of 60 seconds, D for a total of 90 seconds, E for a total of 120 seconds, F for a total of 150 seconds The copper film thickness after removal at each position is shown.
[0151]
According to this example, the film thickness of the copper film at each point decreases almost in proportion to the product of current and time. The thin film thicknesses of the 1-point and 21-point copper films come from the plating characteristics when the Cu film was formed in the previous stage, and are irrelevant to the polishing method of the present invention.
[0152]
【The invention's effect】
  According to the present invention, since the metal film is polished by the combined action of mechanical polishing and electrolytic polishing, the metal film protrusions can be selectively selected very efficiently compared to the case of flattening the metal film by mechanical polishing. Removal and planarization are possible. Further, according to the present invention, since a sufficient polishing rate can be obtained even at a low polishing pressure, it is possible to suppress the occurrence of scratches, dishing, erosion and the like in the polished metal film. In addition, since the damage to the insulating film under the metal film can be suppressed, an organic system having a relatively low mechanical strength as an interlayer insulating film in order to reduce the dielectric constant from the viewpoint of reducing the power consumption and speeding up of the semiconductor device. Even when a low dielectric constant film or a porous low dielectric constant insulating film is used, it can be easily applied. Furthermore, according to the present invention, the polishing process can be managed by monitoring the electrolytic current, and the progress of the polishing process can be accurately grasped.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a manufacturing process of a method for manufacturing a semiconductor device according to the present invention, where (a) shows an insulating film forming process on a semiconductor substrate, and (b) shows a contact hole and a wiring groove. (C) shows up to the formation process of the barrier film.
FIG. 2 shows a step subsequent to FIG. 1, in which (d) shows a process up to the formation of a copper film as a seed film, and (e) shows a process up to the formation of the copper film.
FIG. 3 shows a process continued from FIG. 2, in which (f) shows a copper film anodizing process and (g) shows a chelate film forming process.
4 shows a process subsequent to FIG. 3, in which (h) shows the process up to the removal of the chelate film on the convex part, and (i) shows up to the process of re-forming the chelate film.
5 shows a continuation process of FIG. 4, in which (j) is up to the copper film flattening process, (k) is up to the removal process of excess copper film, and (l) is the exposure of the barrier film. The process is shown.
FIG. 6 is a diagram illustrating a configuration of a polishing apparatus according to the present embodiment.
FIG. 7 is an enlarged view showing the internal structure of the polishing tool holding part of the polishing apparatus according to the present embodiment.
FIG. 8A is a bottom view of an electrode plate used in the polishing apparatus according to the present embodiment, and FIG. 8B is an enlarged view of the vicinity of the electrode plate.
FIG. 9 is a diagram illustrating a positional relationship between a polishing tool and a wafer.
FIG. 10 is a cross-sectional view for explaining electropolishing of the polishing apparatus according to the present invention.
FIG. 11 is an enlarged cross-sectional view taken along a circle C in FIG.
FIG. 12 is an enlarged cross-sectional view taken along a circle D in FIG.
FIG. 13 is a view showing a first modification of the polishing apparatus according to the present invention.
FIG. 14 is a diagram showing a second modification of the polishing apparatus according to the present invention.
FIG. 15 is a view showing a third modification of the polishing apparatus according to the present invention applied to a conventional CMP apparatus.
16 is a diagram for explaining an electrolytic composite polishing operation by the polishing apparatus shown in FIG. 15. FIG.
FIG. 17 is a diagram showing another example of the electrode configuration of the polishing pad.
FIG. 18 is a diagram showing still another example of the electrode configuration of the polishing pad.
FIG. 19 illustrates the present invention.reference1 is a schematic configuration diagram of a polishing apparatus according to an embodiment.
FIG. 20 is a schematic diagram of the present invention.21 is a schematic configuration diagram of a polishing apparatus according to an embodiment.
FIG. 21 is a block diagram of the present invention.3It is a principal part block diagram of the grinding | polishing apparatus which concerns on embodiment.
FIG. 22 is a diagram for explaining a first embodiment of the present invention.
FIG. 23 is a diagram for explaining a second embodiment of the present invention.
FIG. 24 is a diagram for explaining a third embodiment of the present invention.
FIGS. 25A and 25B are cross-sectional views showing a manufacturing process of a copper wiring forming method by a dual damascene method according to a conventional example, where FIG. 25A shows the interlayer insulating film forming process and FIG. 25B shows a wiring groove; (C) shows the process up to the step of forming the barrier film.
FIG. 26 shows a process continued from FIG. 24, in which (d) shows the seed film forming process, (e) shows the wiring layer forming process, and (f) shows the wiring forming process. .
FIG. 27 is a cross-sectional view for explaining dishing that occurs in a copper film polishing step by a CMP method.
FIG. 28 is a cross-sectional view for explaining erosion that occurs in a copper film polishing step by a CMP method.
FIG. 29 is a cross-sectional view for explaining a recess that occurs in a copper film polishing step by a CMP method.
FIG. 30 is a cross-sectional view for explaining scratches and chemical damage that occur in a copper film polishing step by a CMP method.
[Explanation of symbols]
  DESCRIPTION OF SYMBOLS 10 ... Abrasive tool holding part, 11,311,411 ... Abrasive tool, 12 ... Flange member, 13 ... Holding device, 13a ... Main shaft, 14 ... Main shaft motor, 15 ... Cylinder device, 15a ... Piston, 15b ... Piston rod, 16 , 316, 416 ... rotary joint, 20 ... current-carrying shaft, 20a ... supply nozzle, 21 ... pressing member, 22 ... insulating plate, 23 ... electrode plate, 24 ... scrub member, 24a ... wiping member, 25 ... elastic member, 26 ... Connecting member, 27 ... energizing brush, 28 ... energizing member, 30 ... Z-axis positioning mechanism, 31 ... Z-axis servo motor, 31a ... ball screw shaft, 32 ... Z-axis slider, 33 ... guide rail, 40 ... X-axis moving mechanism Part, 42, 342, 442 ... wafer table, 44 ... drive motor, 45 ... holding device, 46 ... belt, 47 ... processing pan, 48 ... X-axis slurry 49 ... X-axis servo motor 51 ... Z-axis driver 52 ... Spindle driver 53 ... Table driver 54 ... X-axis driver 55,555,655 ... Controller 56,556,656 ... Control panel 61 561, 661 ... Electrolytic power source, 62, 562, 662 ... Ammeter, 63 ... Resistance meter, 71 ... Slurry supply device, 81 ... Electrolyte supply device, 101 ... Semiconductor substrate, 102 ... Interlayer insulating film, 103 ... Barrier film, 104 ... Seed film, 105 ... Copper film, 106 ... Chelate film, 120 ... Cathode member, 201 ... Surface plate, 202, 221, 241 ... Polishing pad, 203, 223, 243 ... Cathode electrode, 204 ... Anode electrode, 206, 224, 244 ... insulator, 207 ... wafer chuck, 208 ... electrolyte / slurry supply unit, 210 ... copper film, 410 ... retainer , 501 ... water tank, 510,610 ... electrode plate, 520 ... jet pump, 521,522 ... pipe, 531,631 ... first holding member, 532,632 ... second holding member, 533 ... Z-axis positioning mechanism 634 ... third holding member, 640 ... pulse generator, 641 ... amplifier, 643 ... vibrator, 644 ... fourth holding member, 710 ... energizing brush, SC ... scratch, CD ... chemical damage, EL ... electrolyte, SL …slurry.

Claims (20)

A polishing apparatus for polishing an object to be polished having a copper film on a surface to be polished,
A conductive polishing tool having a polishing surface;
A polishing tool rotation holding means for rotating and holding the polishing tool around a predetermined rotation axis;
The object to be polished rotating and holding means for holding the object to be polished and rotating around a predetermined rotation axis;
Moving positioning means for moving and positioning the polishing tool in a direction substantially perpendicular to the surface to be polished of the object to be polished;
Relative moving means for relatively moving the polished surface and the polished surface along a predetermined plane;
An electrolyte supply means for supplying an electrolyte containing a chelating agent on the surface to be polished;
Current supply means for supplying a current that flows from the surface to be polished to the polishing tool through the electrolyte, using the surface to be polished as an anode and the polishing tool as a cathode ;
The current supply means is disposed so as to be in contact with or close to the surface to be polished, and an anode member for energizing the surface to be polished as an anode, and a power source for applying a predetermined voltage between the anode member and the polishing tool Have
The polishing tool has an annular shape, and one end surface of the annular shape constitutes a polishing surface,
The anode member is provided in a non-contact manner inside the ring of the polishing tool, and is rotated and held together with the polishing tool by the polishing tool rotation holding means.
Polishing equipment. The power source outputs a pulsed voltage having a predetermined period .
The polishing apparatus according to claim 1 . The anode member further includes a cleaning member having a surface for cleaning the surface to be polished on the side facing the surface to be polished, and the cleaning member is formed of a material that can absorb and pass the electrolytic solution. And supplying the electrolytic solution supplied from the anode member side to the surface to be polished .
The polishing apparatus according to claim 1 . Current detection means for detecting a value of a current flowing from the surface to be polished to the polishing tool;
Control means for controlling a position of the polishing tool in a direction substantially perpendicular to the surface to be polished so that the value of the current becomes constant based on a detection signal from the current detection means ;
The polishing apparatus according to claim 1. A polishing apparatus for polishing an object to be polished having a copper film on a surface to be polished,
Holding means for holding the object to be polished;
And the electrode plate that will be positioned parallel to the surface to be polished,
Exciting means comprising a pulse generator, an amplifier and an exciter connected to the object to be polished;
Not contain abrasive grains, and an electrolytic solution containing a chelating agent,
A water tank for storing the electrolyte solution;
Electrolytic current supply means for supplying an electrolytic current flowing from the surface to be polished to the electrode plate through the electrolytic solution using the surface to be polished as an anode and the electrode plate as a cathode ,
The electrolytic current supply means outputs a pulsed voltage every 20 to 50 msec,
The holding means and the electrode plate of the object to be polished are arranged soaked in the electrolyte solution,
The electrolytic current supply means supplies the electrolytic current so that the copper film reacts with the chelating agent to form a chelate film,
The vibration means vibrates the object to be polished so that the convex portion of the chelate film is removed,
Polishing equipment. A polishing apparatus for polishing an object to be polished having a metal film on a surface to be polished,
It wipes the surface to be polished of the object to be polished, and the wiping member vent is provided,
A counter electrode disposed on an upper surface of the wiping member, facing the surface to be polished;
Wiping member rotation holding means for rotating and holding the counter electrode and the wiping member around a predetermined rotation axis;
An object rotation holding means for holding the object to be polished and rotating around a predetermined rotation axis;
An electrolyte supply means for supplying an electrolyte on the surface to be polished;
Current supply means for supplying a current between the surface to be polished and the counter electrode ;
An oscillating shaft that passes through the wiping member rotation holding means and is perpendicularly connected to the counter electrode and a central portion of the wiping member, and has a through hole and energizes the current;
The electrolytic solution is supplied from the electrolytic solution supply means to the polished surface through the wiping member via the through hole.
Polishing equipment. Further comprising a relative movement means for relatively moving the said wiping member and the surface to be polished,
The polishing apparatus according to claim 6 . The relative movement means, the presses the wiping member on the polished surface, the horizontally moving said wiping member on the polished surface,
The polishing apparatus according to claim 7 . The relative movement means, the horizontally moves the object to be polished rotary holding means to the surface to be polished is positioned the on the surface of the polished surface of the wiping member,
The polishing apparatus according to claim 7 . The metal film is a wiring metal film ,
The polishing apparatus according to claim 6 . The wiping member is composed of a elastoplastic material,
The polishing apparatus according to claim 6 . It further includes a bathtub that is formed so as to include the periphery of the object to be polished and that stores the electrolyte supplied by the electrolyte supply means .
The polishing apparatus according to claim 6 . The electrolytic solution supply means supplies an electrolytic solution containing an electrolyte and an additive .
The polishing apparatus according to claim 6 . The additive includes at least one of a brightener, a chelating agent, and copper ions .
The polishing apparatus according to claim 13 . The counter electrode has an equivalent or noble metal material as compared to the metal film on the surface to be polished .
The polishing apparatus according to claim 6 . The counter electrode is provided with a vent hole ,
The polishing apparatus according to claim 6 . A contact electrode for guiding current from the current supply means to the metal film on the surface to be polished ;
The polishing apparatus according to claim 6 . The current supply means supplies a current by applying a periodic pulse between the surface to be polished and the counter electrode .
The polishing apparatus according to claim 6 . The current supply means can change the value of the current flowing between the surface to be polished and the counter electrode at least in the vicinity of the polishing initial point and the polishing end point .
The polishing apparatus according to claim 6 . A temperature adjusting means for adjusting the temperature of the electrolyte supplied by the electrolyte supply means ;
The polishing apparatus according to claim 6 .

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