JP3919474B2 - Plating method and plating apparatus - Google Patents

Description

【００８７】
【表２】

【００８８】
（実施例１）
錯体浴組成１の銅めっき液を第１の実施の形態の第１のめっき処理部２２ａの銅めっき液に使用し、電流密度０.５Ａ／ｄｍ^２ 、めっき時間２５秒の第１段めっき処理（シード層補強）を行い、しかる後、硫酸銅浴組成１の銅めっき液を第２のめっき処理部２２ｂの銅めっき液に使用し、電流密度２.５Ａ／ｄｍ^２ 、めっき時間２分の第２段めっき処理（銅の埋込み）を行った。
【００９０】
（実施例２）
錯体浴組成３の銅めっき液を第１の実施の形態の第１のめっき処理部２２ａの銅めっき液に使用し、電流密度０.５Ａ／ｄｍ^２、めっき時間２５秒の第１段めっき処理（シード層補強）を行い、しかる後、硫酸銅浴組成１の銅めっき液を第２のめっき処理部２２ｂの銅めっき液に使用し、電流密度２.５Ａ／ｄｍ^２、めっき時間２分の第２段めっき処理（銅の埋込み）を行った。
【００９２】
（比較例１）
硫酸銅浴組成１の銅めっき液を使用し、電流密度２.５Ａ／ｄｍ^２ 、めっき時間２分のめっき処理（銅の埋込み）を行った。
【００９３】
（比較例２）
硫酸銅浴組成２の銅めっき液を使用し、電流密度２.５Ａ／ｄｍ^２ 、めっき時間２分のめっき処理（銅の埋込み）を行った。
【００９４】
これらの実施例１，２及び比較例１，２によって微細窪みに埋込んだ銅の欠陥の有無をＳＥＭ観察した。ここで、電析不良有りとは、図２３（ａ）に示すように、溝の底部に銅が析出しない空洞部Ｖ_１を有する状態を指し、シームボイド有りとは、図２３（ｂ）に示すように、銅の内部に細長いボイドＶ_２を有する状態を指し、粒状のボイド有りとは、図２３（ｃ）に示すように、銅の内部に粒状のボイドＶ_３を有する状態を指す。
【００９５】
【表３】

これにより、実施例１及び２にあっては、電析不良やボイドのない銅の埋込みを行えることが判る。
【００９６】
次に、表４に示す錯体浴組成１〜４からなる銅めっき液と、表５に示す硫酸銅浴組成１，２からなる銅めっき液を作成し、前記実施例１，２及び比較例１，２と同様にめっき処理を施したところ、前記とほぼ同様な結果が得られた。
【００９７】
【表４】

【００９８】
【表５】

【００９９】
以上説明したように、本発明によれば、銅めっき液中に錯化剤を有することで、めっき浴としての分極を大きくして、シード層の薄い部分の補強や高アスペクト比のトレンチやホール等の微細窪みの奥までの銅の均一な埋込みが可能となり、しかも析出するめっきは緻密であり、マイクロボイドの危険も回避できる。更に、アルカリ金属及びシアンを含んでいないので、アルカリ金属の存在に伴うエレクトロマイグレーションによって半導体を劣化させてしまうことを防止するとともに、シアンの使用を避けるとの要請に応えることができる。
【０１００】
図２４は、本発明に係るめっき装置の他の実施の形態の平面配置構成を示す図である。このめっき装置は、第１搬送装置６００及び第２搬送装置６０２を囲むように、ロード・アンロード部６０４、２基のアニール処理部６０６及び洗浄処理部６０８が配置され、更に、洗浄処理部６０８、４基のめっき処理部６１０に囲まれた位置に第３搬送装置６１２が配置された構成である。更に、各めっき処理部６１０にめっき液を供給する薬液供給システム６１４が備えられている。
【０１０１】
このめっき装置で、図２１に示すように、シード層の補強と銅の埋込みの２段のめっき処理を行うときには、４基のめっき処理部６１０の少なくとも１基を、前述と同様な組成の第１のめっき液を使用した第１段めっき処理用のめっき処理部として、他をめっき処理部６１０を、前述と同様な組成の第２のめっき液を使用した第２段めっき処理用のめっき処理部として使用する。
【０１０２】
図２５は、例えば半導体基板Ｗの表面にめっきを施して銅膜からなる配線を形成し、更にこの配線の表面を無電解めっきによる保護層で選択的に覆って保護するようにした工程の一例を示す。
【０１０３】
半導体基板Ｗには、図２５（ａ）に示すように、半導体素子が形成された基板１００の導電層１０１ａの上にＳｉＯ_２からなる絶縁膜１０２が堆積され、リソグラフィ・エッチング技術によりコンタクトホール１０３と配線用の溝１０４が形成され、その上にＴａＮ等からなるバリア層１０５、更にその上にシード層１０７が形成される。なおシード層１０７は、スパッタなどによって予め形成しておき、このシード層１０７の上にこれを補強するために補強シード層を形成してもよい。そして図２５（ｂ）に示すように、半導体基板Ｗ表面に銅めっきを施すことで、半導体基板Ｗのコンタクトホール１０３及び溝１０４内に銅を充填させると共に、絶縁膜２上に銅膜１０６を堆積させる。その後化学的機械的研磨（ＣＭＰ）により絶縁膜１０２上の銅膜１０６を除去して、図２５（ｃ）に示すように、コンタクトホール１０３および配線用の溝１０４に充填した銅膜１０６の表面と絶縁膜１０２の表面とを略同一平面にし、露出する金属表面の上に配線保護膜１０８を形成する。
【０１０４】
図２６は、無電解めっき装置の概略構成図である。図２６に示すように、この無電解めっき装置は、被めっき部材である半導体基板Ｗをその上面に保持する保持手段３１１と、保持手段３１１に保持された半導体基板Ｗの被めっき面（上面）の周縁部に当接して該周縁部をシールする堰部材３３１と、堰部材３３１でその周縁部をシールされた半導体基板Ｗの被めっき面にめっき液を供給するシャワーヘッド３４１を備えている。無電解めっき装置は、さらに保持手段３１１の上部外周近傍に設置されて半導体基板Ｗの被めっき面に洗浄液を供給する洗浄液供給手段３５１と、排出された洗浄液等（めっき廃液）を回収する回収容器３６１と、半導体基板Ｗ上に保持しためっき液を吸引して回収するめっき液回収ノズル（図示せず）と、前記保持手段３１１を回転駆動するモータ（回転駆動手段）Ｍとを備えている。
【０１０５】
保持手段３１１の上方には、ランプヒータ３１７が設置され、このランプヒータ３１７とシャワーヘッド３４１とは一体化されている。即ち、例えば複数の半径の異なるリング状のランプヒータ３１７を同心円状に設置し、ランプヒータ３１７の間の隙間からシャワーヘッド３４１の多数のノズル３４３をリング状に開口させている。なおランプヒータ３１７としては、渦巻状の一本のランプヒータで構成しても良いし、さらにそれ以外の各種構造・配置のランプヒータで構成しても良い。
【０１０６】
保持手段３１１は、その上面に半導体基板Ｗを載置して保持する基板載置部３１３を設けている。この基板載置部３１３は半導体基板Ｗを載置して固定するように構成されており、具体的には半導体基板Ｗをその裏面側に真空吸着する図示しない真空吸着機構を設置している。この保持手段３１１はモータＭによって回転駆動されると共に、図示しない昇降手段によって上下動できるように構成されている。堰部材３３１は筒状であってその下部に半導体基板Ｗの外周縁をシールするシール部３３３を設け、図示の位置から上下動しないように設置されている。
【０１０７】
シャワーヘッド３４１は、多数のノズル３４３を設けることで、供給されためっき液をシャワー状に分散して半導体基板Ｗの被めっき面に略均一に供給する構造のものである。また洗浄液供給手段３５１は、ノズル３５３から洗浄液を噴出する構造である。めっき液回収ノズルは上下動且つ旋回できるように構成されていて、その先端が半導体基板Ｗの上面周縁部の堰部材３３１の内側に下降して半導体基板Ｗ上のめっき液を吸引するように構成されている。
【０１０８】
次にこの無電解めっき装置の動作を説明する。まず図示の状態よりも保持手段３１１を下降して堰部材３３１との間に所定寸法の隙間を設け、基板載置部３１３に半導体基板Ｗを載置・固定する。半導体基板Ｗとしては例えばφ８インチウエハを用いる。
【０１０９】
次に、保持手段３１１を上昇して図示のようにその上面を堰部材３３１の下面に当接し、同時に半導体基板Ｗの外周を堰部材３３１のシール部３３３によってシールする。このとき半導体基板Ｗの表面は開放された状態となっている。
【０１１０】
次に、ランプヒータ３１７によって半導体基板Ｗ自体を直接加熱して、例えば半導体基板Ｗの温度を７０℃にし（めっき終了まで維持する）、次にシャワーヘッド３４１から例えば５０℃に加熱されためっき液を噴出して半導体基板Ｗの表面の略全体にめっき液を降り注ぐ。半導体基板Ｗの表面は堰部材３３１によって囲まれているので、注入しためっき液は全て半導体基板Ｗの表面に保持される。供給するめっき液の量は半導体基板Ｗの表面に１ｍｍ厚（約３０ｍｌ）となる程度の少量で良い。なお被めっき面上に保持するめっき液の深さは１０ｍｍ以下であれば良く、１ｍｍでも良い。このように供給するめっき液が少量で済めばこれを加熱する加熱装置も小型のもので良くなる。そしてこの例においては、半導体基板Ｗの温度を７０℃に、めっき液の温度を５０℃に加熱しているので、半導体基板Ｗの被めっき面は例えば６０℃になり、めっき反応に最適な温度にできる。このように半導体基板Ｗ自体を加熱するように構成すれば、加熱するのに大きな消費電力の必要なめっき液の温度をそれほど高く昇温しなくても良いので、消費電力の低減化やめっき液の材質変化の防止が図れ、好適である。なお半導体基板Ｗ自体の加熱のための消費電力は小さくて良く、また半導体基板Ｗ上に溜めるめっき液の量は少ないので、ランプヒータ３１７による半導体基板Ｗの保温は容易に行え、ランプヒータ３１７の容量は小さくて良く装置のコンパクト化を図ることができる。また半導体基板Ｗ自体を直接冷却する手段をも用いれば、めっき中に加熱・冷却を切替えてめっき条件を変化させることも可能である。半導体基板上に保持されているめっき液は少量なので、感度良く温度制御が行える。
【０１１１】
そして、モータＭによって半導体基板Ｗを瞬時回転させて被めっき面の均一な液濡れを行い、その後半導体基板Ｗを静止した状態で被めっき面のめっきを行う。具体的には、半導体基板Ｗを１ｓｅｃだけ１００ｒｐｍ以下で回転して半導体基板Ｗの被めっき面上をめっき液で均一に濡らし、その後静止させて１ｍｉｎ間無電解めっきを行わせる。なお瞬時回転時間は長くても１０ｓｅｃ以下とする。
【０１１２】
上記めっき処理が完了した後、めっき液回収ノズル３６５の先端を半導体基板Ｗの表面周縁部の堰部材３３１内側近傍に下降し、めっき液を吸い込む。このとき半導体基板Ｗを例えば１００ｒｐｍ以下の回転速度で回転させれば、半導体基板Ｗ上に残っためっき液を遠心力で半導体基板Ｗの周縁部の堰部材３３１の部分に集めることができ、効率良く、且つ高い回収率でめっき液の回収ができる。そして保持手段３１１を下降させて半導体基板Ｗを堰部材３３１から離し、半導体基板Ｗの回転を開始して洗浄液供給手段３５１のノズル３５３から洗浄液（超純水）を半導体基板Ｗの被めっき面に噴射して被めっき面を冷却すると同時に希釈化・洗浄することで無電解めっき反応を停止させる。このときノズル３５３から噴射される洗浄液を堰部材３３１にも当てることで堰部材３３１の洗浄を同時に行っても良い。このときのめっき廃液は、回収容器３６１に回収され、廃棄される。
【０１１３】
なお、一度使用しためっき液は再利用せず、使い捨てとする。前述のようにこの装置において使用されるめっき液の量は従来に比べて非常に少なくできるので、再利用しなくても廃棄するめっき液の量は少ない。なお場合によってはめっき液回収ノズルを設置しないで、使用後のめっき液も洗浄液と共にめっき廃液として回収容器３６１に回収しても良い。
そしてモータＭによって半導体基板Ｗを高速回転してスピン乾燥した後、保持手段３１１から取り出す。
【０１１４】
図２７は 研磨処理部を一体に組み込んで、めっき直後に基板表面の研磨が行えるようにした、本発明の他の実施の形態のめっき装置を示す全体配置図である。このめっき装置は、ロード・アンロードを行う基板カセット５３１，５３１と、めっき処理部５１２と、基板を洗浄する洗浄処理部５３５，５３５と、２台の搬送装置５１４ａ，５１４ｂと、反転機５３９，５３９と、研磨処理部５４１，５４１と、スピン乾燥機５３４とを備えている。
【０１１５】
そして基板Ｗの流れは、例えば以下の通りである。まず搬送装置５１４ａが何れかのロード用の基板カセット５３１から処理前の基板Ｗを取り出し、めっき処理部５１２でめっき処理を施した後、搬送装置５１４ａが基板Ｗを何れかの反転機５３９に受け渡しその被処理面を下向きにした後、もう一方の搬送装置５１４ｂに受け渡される。搬送装置５１４ｂは基板Ｗを何れかの研磨処理部５４１に受け渡し、所定の研磨がなされる。研磨後の基板Ｗは搬送装置５１４ｂによって取り出され、何れかの洗浄処理部５３５で洗浄された後、他方の研磨処理部５４１に受け渡されて再度研磨された後、搬送装置５１４ｂにより他方の洗浄処理部５３５に搬送されて洗浄が行われる。洗浄後の基板Ｗは、搬送装置５１４ｂにより他方の反転機５３９に搬送されて被処理面が上向きに反転された後、搬送装置５１４ａによりスピン乾燥機５３４に搬送されてスピン乾燥され、その後再び搬送装置５１４ａによりアンロード用の基板カセット５３１に収納される。
【０１１６】
図２８は、この種の研磨処理部５４１の一例を示す。図２８に示すように、トップリング１０−２は半導体基板Ｗを吸着し、研磨テーブル１０−１の研磨面１０−１ａに半導体基板Ｗの銅膜６（図３９（ｂ）参照）形成面を当接押圧して研磨を行う。この研磨では、基本的に銅膜６が研磨される。研磨テーブル１０−１の研磨面１０−１ａはＩＣ１０００のような発泡ポリウレタン、又は砥粒を固定若しくは含浸させたもので構成されている。該研磨面１０−１ａと半導体基板Ｗの相対運動で銅膜６が研磨される。
【０１１７】
上記銅膜６の研磨を行うための砥粒、若しくはスラリーノズル１０−６から噴出されるスラリーには、シリカ、アルミナ、セリア等が用いられ、酸化剤としては、過酸化水素等の主に酸性の材料でＣｕを酸化させる材料を用いる。研磨テーブル１０−１内には温度を所定の値に保つため、所定の温度に調温された液体を通すための調温流体配管５４２が接続されている。スラリーの温度も所定の値に保つため、スラリーノズル１０−６には温度調整器１０−７が設けられている。また図示は省略するが、ドレッシング時の水等は、調温されている。このように、研磨テーブル１０−１の温度、スラリーの温度、ドレッシング時の水等の温度を所定の値に保つことにより、化学反応速度を一定に保っている。特に研磨テーブル１０−１には、熱伝導性のよいアルミナやＳｉＣ等のセラミックが用いられる。
【０１１８】
研磨の終点の検知には、研磨テーブル１０−１に設けた渦電流式の膜厚測定機１０−８若しくは光学式の膜厚測定機１０−９を使用し、銅膜６の膜厚測定、若しくはバリア膜５（図３９（ａ）参照）の表面検知を行って、銅膜６の膜厚が０又はバリア膜５の表面を検知したら研磨（一次研磨）の終点とする。
【０１１９】
図２９は、上記研磨テーブル１０−１の研磨面１０−１ａを洗浄する洗浄機構の構成を示す図である。図示するように研磨テーブル１０−１の上方には、純水と窒素ガスを混合して噴射する混合噴射ノズル１０−１１ａ〜１０−１１ｄが複数個（図では４個）配置されている。各混合噴射ノズル１０−１１ａ〜１０−１１ｄには、窒素ガス供給源２１４からレギュレータ２１６で圧力調整された窒素ガスがエアオペレータバルブ２１８を通して供給されると共に、純水供給源２１５からレギュレータ２１７で圧力を調整された純水がエアオペレータバルブ２１９を通して供給される。
【０１２０】
混合された気体と液体は、噴射ノズルによってそれぞれ液体及び／又は気体の圧力、温度、ノズル形状などのパラメータを変更することによって、供給する液体はノズル噴射によりそれぞれ、▲１▼液体微粒子化、▲２▼液体が凝固した微粒子固体化、▲３▼液体が蒸発して気体化（これら▲１▼、▲２▼、▲３▼をここでは霧状化又はアトマイズと呼ぶ）され、液体由来成分と気体成分の混合体が研磨テーブル１０−１の研磨面に向けて所定の方向性を有して噴射される。
【０１２１】
研磨面１０−１ａとドレッサー１０−１０の相対運動により、研磨面１０−１ａを再生（ドレッシング）するとき、混合噴射ノズル１０−１１ａ〜１１−１１ｄから純水と窒素ガスの混合流体を研磨面１０−１ａに噴射して洗浄する。窒素ガスの圧力と純水の圧力は独立して設定できるようになっている。この例では純水ライン、窒素ラインともにマニュアル駆動のレギュレータを用いているが、外部信号に基づいて設定圧力を変更できるレギュレータをそれぞれ用いても良い。上記洗浄機構を用いて研磨面１０−１ａを洗浄した結果、５〜２０秒の洗浄を行なうことにより、上記研磨工程で研磨面上に残ったスラリーを除去することができた。
【０１２２】
図３０は搬送装置５１４ａ（５１４ｂ）を示す斜視図である。また図３１は前記搬送装置５１４ａ（５１４ｂ）に取付けられるロボットハンド５４０を示す図であり、図３１（ａ）は平面図、図３１（ｂ）は側断面図である。
【０１２３】
搬送装置５１４ａ（５１４ｂ）は、ロボット本体５４３の上部に取付けた二本のアーム５４２，５４２の先端にそれぞれロボットハンド５４０，５４０を取付けて構成されている。両ロボットハンド５４０，５４０は上下に所定の隙間を介して重なるように配置されている。そしてアーム５４２が伸縮することによりロボットハンド５４０上に載置した基板Ｗの前後方向への搬送を可能にしている。またロボット本体５４３が回転及び／又は移動することで任意の方向への基板Ｗの搬送が可能となる。
【０１２４】
そして図３１に示すようにロボットハンド５４０には、直接４つの膜厚センサＳが埋め込まれて取付けられている。膜厚センサＳとしては、膜厚を測定できるものであれば何でも良いが、好ましくは渦電流センサを用いる。なお渦電流センサは渦電流を発生させ、基板Ｗを導通して帰ってきた電流の周波数や損失を検出することにより膜厚を測定するものであり、非接触で用いられる。更に膜厚センサＳとしては、光学的センサも好適である。光学的センサは、試料に光を照射し、反射する光の情報から膜厚を直接的に測定することができるものであり、金属膜だけでなく酸化膜などの絶縁膜の膜厚測定も可能である。膜厚センサＳの設置位置は図示のものに限定されず、測定したい箇所に任意の個数を取付ける。またロボットハンド５４０には乾いた基板Ｗを扱うドライハンドと、濡れた基板Ｗを扱うウエットハンドがあり、どちらにも前記膜厚センサＳを取付けることが可能である。しかしながらこの搬送装置５１４ａ（５１４ｂ）を、めっき処理部５１２に用いた場合は、シード層のみ付いた状態で最初に基板Ｗの膜厚を測定する必要があるため、基板カセット５３１，５３１に基板Ｗが置かれているドライの状態で最初に基板Ｗの厚さを測定する必要がある。したがってドライハンドに膜厚センサＳを取付けるのが望ましい。
【０１２５】
膜厚センサＳで検出された信号は演算装置に送られ、処理前の基板Ｗの膜厚と処理後の基板Ｗの膜厚との差分を取る等の演算が行われ、膜厚を所定のディスプレイ等に出力する。演算方法は膜厚を適切に測定できればいかなる方法でも良い。
【０１２６】
この例によれば、ロボットハンド５４０が基板Ｗを搬送している最中に膜厚を測定できるため、基板処理工程中にわざわざ別途膜厚測定工程を設ける必要がなく、スループットを低下させることがないという効果が得られる。またロボットハンド５４０に膜厚センサＳを取付けるため、省スペース化が実現できる。
【０１２７】
図３２は、搬送装置５１４ａ（５１４ｂ）の他の例を示す図であり、図３２（ａ）は概略平面図、図３２（ｂ）は概略側面図である。図３２に示すように、この例では、ロボット本体５４３のロボットハンド５４０の下部に５つの膜厚センサＳを取付けている。即ちロボットハンド５４０の下部に基板Ｗと略同サイズの円盤状の取付け板５４５を設置し、この取付け板５４５の上に５つの膜厚センサＳを取付ける。取付け板５４５はロボット本体５４３に固定されているが、他の部材に固定しても良い。
【０１２８】
各膜厚センサＳは、図示するようにロボットハンド５４０と重ならない位置に取付けることにより、基板Ｗ全体の広い領域での膜厚の測定が可能となる。またこの例によっても省スペース化を実現でき、極めて短時間で測定が可能となる。そして取付け板５４５の上で基板Ｗを停止させることで基板Ｗの固定点における膜厚の測定が可能になり、一方、停止させないで取付け板５４５上をロボットハンド５４０上の基板Ｗが通過するようにすればスキャンしながらの測定も可能になる。また膜厚センサＳはロボット本体５４３と一体であるため、安定した検出が行える。また、取付け板５４５をロボット本体５４３でなく他の部材に固定した場合は、ロボットハンドの高さを任意に変えることで、基板Ｗとセンサ間の距離を調整することも可能となる。
【０１２９】
検出後の信号が演算装置に送られて膜厚が測定される点は、図３１に示す例と同様である。但し、スキャンしながらの測定の場合は、測定点が時間の経過と共に変化するため、移動平均法により演算して膜厚を算出するのが好適である。
【０１３０】
図３３は、膜厚測定の他の例を示す図であり、図３３（ａ）は概略平面図、図３３（ｂ）は概略側面図である。図３３に示す例では、図２７に示すめっき処理部５１２の基板Ｗの出入口部５５０の上部に３つの膜厚センサＳを設置している。即ち、出入口部５５０の上部に長方形状の取付け板５５１を設置し、この取付け板５５１の下面に３つの膜厚センサＳを直列に取付ける。取付け板５５１はめっき処理部５１２に固定しても良いし、搬送装置５１４ａ（５１４ｂ）のロボット本体５４３に固定しても良いし、それ以外の部材に固定しても良い。
【０１３１】
このように構成すれば、めっき処理部５１２に基板Ｗを入れる際と出す際の何れにおいても膜厚センサＳが基板Ｗを走査することとなるため、スキャン測定に適している。またこの例のように膜厚センサＳを何列か設置することにより、基板Ｗ上の任意の点をスキャン測定することができる。また、ロボットハンドの高さを任意に変えることで、基板Ｗとセンサ間の距離を調整することが可能である。
この膜厚センサＳで検出された信号は、演算装置により演算されるが、スキャン測定の場合は、移動平均法による演算処理が好適である。
【０１３２】
また、図２７に示す研磨処理部５４１の基板Ｗを出し入れする出入口付近に前記膜厚センサＳを設置しても良い。なお研磨処理部５４１に基板Ｗを搬入するときは基板Ｗの被処理面は下向きであるため、研磨処理部５４１の基板Ｗを搬入する場所の下側に膜厚センサＳを設置することが好ましい（もちろん上側に膜厚センサＳを設置しても膜厚測定は可能であるが、下側の方がより精度がよくなる）。研磨が終了した後は、基板Ｗの被処理面がウエットな状態であるが、ウエットな状態でも測定可能な膜厚センサを用いれば前記めっき処理部５１２の場合と同様な方法で膜厚が測定できる。
【０１３３】
図３４は、反転機５３９付近の概略正面図、図３５は反転アーム５５３，５５３部分の平面図である。図３４及び図３５に示すように、反転アーム５５３，５５３は、基板Ｗの外周をその左右両側から挟み込んで保持し、これを１８０°回動することで反転させる機能を有する。そしてこの反転アーム５５３，５５３の直下に円形の取付け台５５５を設置し、取付け台５５５上に複数の膜厚センサＳを設置する。取付台５５５は駆動機構５５７によって上下動自在に構成されている。
【０１３４】
そして基板Ｗの反転時には、取付け台５５５は基板Ｗの下方の実線の位置に待機しており、反転の前又は後に取付け台５５５を点線で示す位置まで上昇して膜厚センサＳを反転アーム５５３，５５３に把持した基板Ｗに接近させ、その膜厚を測定する。
【０１３５】
この例によれば、搬送ロボット５１４のアーム５４２などの制約がないため、取付け台５５５上の任意の位置に膜厚センサＳを設置できる。また、取付け台５５５は上下動自在な構成となっているので、測定時に基板Ｗとセンサ間の距離を調整することも可能である。また、検出目的に応じた複数の種類のセンサを取付けて、各々のセンサの測定毎に基板Ｗと各センサ間の距離を変更することも可能である。但し取付け台５５５が上下動するため、測定時間をやや要することになる。
【０１３６】
図３６は、本発明の更に他の実施の形態のめっき装置の全体配置図を示す。このめっき装置は、ロード・アンロード部９１５、各一対のアニール処理部９８６、ベベルエッチ・薬液洗浄部９８４及び基板ステージ９７８、基板を１８０゜反転させる機能を有する水洗部９８２、図１９に示す第１段めっき処理（シード層補強）を行う１基の第１のめっき処理部９８０及び図１９に示す第２段めっき処理（銅の埋込み）を行う３基の第２のめっき処理部９７２を有している。更に、ロード・アンロード部９１５、アニール処理部９８６、ベベルエッチ・薬液洗浄部９８４及び基板ステージ９７８の間で基板の受渡しを行う走行自在な第１搬送装置９１７と、基板ステージ９７８、水洗部９８２、第１のめっき処理部９８０及び第２のめっき処理部９７２の間で基板の受渡しを行う走行自在な第２搬送装置９２４が備えられている。
【０１３７】
この例では、先ず、表面にシード層７（図３９（ａ）参照）を形成した基板Ｗをロード・アンロード部９１５から第１搬送装置９１７で一枚ずつ取り出し、基板ステージ９７８を経由して第１のめっき処理部９８０に搬入する。
【０１３８】
次に、この第１のめっき処理部９８０で、基板の表面に第１のめっき液を使用した第１段めっき処理を施して、シード層７の薄肉部を補強しこれを完全なものとする。この第１のめっき液は、前述のように、例えばピロリン酸銅をベースとして、これにピロリン酸等の錯化剤を添加することで、通常の硫酸銅めっき液よりも分極を高めたものである。
そして、第１段めっき処理終了後、必要に応じて、基板Ｗを水洗部９８２に搬送して水洗し、しかる後、水洗後の基板Ｗを第２のめっき処理部９７２の一つに搬送する。
【０１３９】
次に、この第２のめっき処理部９７２で、基板Ｗの表面に第２のめっき液を使用した第２段めっき処理を施して、銅の埋込みを行う。この時、第１段めっき処理を施すことで、シード層７（図３９（ａ）及び図４０（ａ）参照）が補強されて薄肉部のない完全なものとなっているため、シード層７に均一に電流が流れて、ボイドのない銅の埋込みが可能となる。この第２のめっき液は、前述のように、例えば硫酸の濃度が低いレベリング性の優れた組成を有するものである。
【０１４０】
第２段めっき処理終了後、必要に応じて、基板Ｗを水洗部９８２に搬送して水洗し、しかる後、水洗後の基板Ｗをベベルエッチ・薬液洗浄部９８４に搬送する。そして、このベベルエッチ・薬液洗浄部９８４で、銅めっき処理後の基板Ｗを薬液で洗浄するとともに、基板Ｗのベベル部に薄く形成された銅薄膜等をエッチング除去し、更に純水でリンスした後、高速回転させてスピンドライする。しかる後、このスピンドライ後の基板をアニールユニット９８６に搬送してアニールし、アニール終了後に、第１搬送装置９１７でロード・アンロード部９１５のカセットに戻す。
【０１４１】
図３７は、本発明の更に他の実施の形態のめっき装置の全体配置図である。このめっき装置は、ロード・アンロード部８００と処理部８０２と備え、半導ウエハのスループット等を考慮して、この処理部８０２の中央部に１台の搬送装置８０４を、搬送装置８０４の周囲に複数のめっき処理部８０６と洗浄・乾燥処理部（スピン−リンス−ドライユニット）８０８をそれぞれ配置したものである。この例では、１台の搬送装置８０４の周りに３台のめっき処理部８０６と３台の洗浄・乾燥処理部８０８を配置している。なお、洗浄・乾燥処理部８０６の代わりに、ベベルエッチ・薬液洗浄部を配置してもよい。めっき処理部８０８は、いわゆるフェィスアップ型でもよいし、いわゆるフェースダウン型でもよい。
【０１４２】
図３８は、本発明の更に他の実施の形態のめっき装置の全体配置図である。このめっき装置は、ロードステーション８２０内に位置して、半導体ウエハ等の基板Ｗを収納した基板カセット８２２を搭載する２台のカセットテーブルアニール処理部８３０を有している。また、メインフレーム８３２内に位置して、１対の洗浄乾燥部８３４、前述の第１段めっき処理を行う１対の第１のめっき処理部８３６及び前述の第２段めっき処理を行う２対の第２のめっき処理部８３８とを有している。
【０１４３】
そして、ロードステーション８２０内に位置して、基板カセット８２２、アニール処理部８３０及び洗浄・乾燥部８３４との間で基板の受渡しを行う第１搬送装置８４０が、メインフレーム８３２内に位置して、洗浄乾燥部８３４、第１のめっき処理部８３６及び第２のめっき処理部８３８との間で基板の受渡しを行う第２の搬送装置８４２がそれぞれ配置されている。
【０１４４】
図４１は、本発明の更に他の実施の形態のめっき装置の全体配置図である。このめっき装置は、ロード・アンロード部９００、アニール処理部９０３、２基のベベルエッチ・薬液洗浄部９０２、基板ステージ９０６及び３基のめっき処理部９０１とを有している。更に、ロード・アンロード部９００と基板ステージ９０６との間で基板の受渡しを行う走行自在な第１搬送装置９０４と、基板ステージ９０６、アニール処理部９０３、ベベルエッチ・薬液洗浄部９０２及びめっき処理部９０１との間で基板の受渡しを行う走行自在な第２搬送装置９０５が備えられている。
【０１４５】
図４２は、本発明の更に他の実施の形態のめっき装置の全体配置図である。このめっき装置は、ロード・アンロード部１０００、ベベルエッチ・薬液洗浄部１０５０、洗浄・乾燥処理部（スピン−リンス−ドライユニット）１０４０、図１９に示す第１段めっき処理（シード層補強）を行う１基の第１のめっき処理部１０１０、図１９に示す第２段めっき処理（銅の埋込み）を行う２基の第２のめっき処理部１０２０及び第１のめっき処理と第２のめっき処理との間で基板を洗浄する洗浄部１０３０を有している。更に、ロード・アンロード部１０００、ベベルエッチ・薬液洗浄部１０５０及び洗浄・乾燥処理部１０４０との間で基板の受渡しを行う第１搬送装置１０６０と、ベベルエッチ・薬液洗浄部１０５０、洗浄・乾燥処理部１０４０、第１のめっき処理部１０１０、第２のめっき処理部１０２０及び洗浄部１０３０との間で基板の受渡しを行う走行自在な第２搬送装置１０７０が備えられている。
【０１４６】
なお、図４１に示すめっき処理部９０１、図４２に示すめっき処理部１０１０，１０２０を、適宜、前記第１のめっき液を用いて第１段めっき処理を行う第１のめっき処理部、第２のめっき液を用いて第２段めっき処理を行う第２のめっき処理部として使用してもよいことは勿論である。
【０１４７】
【発明の効果】
以上説明したように、本発明によれば、銅めっき液中に錯化剤を有することで、めっき浴としての分極を大きくして、シード層の薄い部分の補強や高アスペクト比のトレンチやホール等の微細窪みの奥までの銅の均一な埋込みが可能となり、しかも析出するめっきは緻密であり、マイクロボイドの危険も回避できる。更に、アルカリ金属及びシアンを含んでいないので、アルカリ金属の存在に伴うエレクトロマイグレーションによって半導体を劣化させてしまうことを防止するとともに、シアンの使用を避けるとの要請に応えることができる。
【図面の簡単な説明】
【図１】本発明の実施の形態のめっき装置の平面配置図である。
【図２】図１に示すめっき装置内の気体の流れを示す説明図である。
【図３】図１に使用されているめっき処理部のめっき処理時における全体を示す断面図である。
【図４】めっき処理部のめっき液の流れの状態を示すめっき液フロー図である。
【図５】めっき処理部の非めっき時（基板受渡し時）における全体を示す断面図である。
【図６】めっき処理部のメンテナンス時における全体を示す断面図である。
【図７】めっき処理部の基板の受渡し時におけるハウジング、押圧リング及び基板の関係の説明に付する断面図である。
【図８】図７の一部拡大図である。
【図９】めっき処理部のめっき処理時及び非めっき時におけるめっき液の流れの説明に付する図である。
【図１０】めっき処理部の芯出し機構の拡大断面図である。
【図１１】めっき処理部の給電接点（プローブ）を示す断面図である。
【図１２】洗浄・乾燥処理部の概略構成例を示す図である。
【図１３】ベベルエッチ・薬液洗浄部の概略構成例を示す図である。
【図１４】洗浄・乾燥処理部及びベベルエッチ・薬液洗浄部に使用される回転保持装置を示す側面図である。
【図１５】図１４の平面図である。
【図１６】図１４に示す回転保持装置における円板状部材を支持するための保持部材の詳細を示す部分断面図である。
【図１７】図１６のＡ−Ａ線に沿って見た図である。
【図１８】搬送装置を示す図で、（ａ）は外観を示す図、（ｂ）はロボットハンドの平面図、（ｃ）はロボットハンドの断面図である。
【図１９】本発明の実施の形態のめっき方法における処理の流れを示す図である。
【図２０】２つの異なる分極の銅めっき液における電圧と電流密度の関係を示すグラフである。
【図２１】 他のめっき方法における処理の流れを示す図である。
【図２２】実施例における錯体浴１〜３及び硫酸銅浴１の電流・電圧曲線を示すグラフである。
【図２３】ＳＥＭ観察における電析不良、シームボイド及び粒状のボイドを模式的に示す図である。
【図２４】本発明のめっき装置の他の例を示す平面配置図である。
【図２５】めっき工程の他の例を示す模式図である。
【図２６】無電解めっき処理部の概略構成図である。
【図２７】研磨処理部を組込んだめっき装置の平面配置図である。
【図２８】研磨処理部の概略構成例を示す図である。
【図２９】研磨テーブル洗浄機の概略構成を示す図である。
【図３０】搬送装置を示す斜視図である。
【図３１】搬送装置に取付けられるロボットハンドを示す図であり、（ａ）は平面図、（ｂ）は側断面図である。
【図３２】搬送装置の他の例を示す図であり、（ａ）は概略平面図、（ｂ）は概略側面図である。
【図３３】膜厚測定の更に他の例を示す図であり、（ａ）は概略平面図、（ｂ）は概略側面図である。
【図３４】反転機付近の概略正面図である。
【図３５】反転アーム部分の平面図である。
【図３６】本発明のめっき装置の更に他の例を示す平面配置図である。
【図３７】本発明のめっき装置の更に他の例を示す平面配置図である。
【図３８】本発明のめっき装置の更に他の例を示す平面配置図である。
【図３９】銅めっき処置によって銅配線を形成する例を工程順に示す図である。
【図４０】従来例におけるシード層の状態と、それに伴って生じするボイドを模式的に示す図である。
【図４１】本発明のめっき装置の更に他の例を示す平面配置図である。
【図４２】本発明のめっき装置の更に他の例を示す平面配置図である。
【符号の説明】
５ バリア層
６ 銅膜
７ シード層
１０ ロード・アンロード部
１２ 洗浄・乾燥処理部
１４ 第１基板ステージ
１６ ベベルエッチ・薬液洗浄部
１８ 第２基板ステージ
２０ 水洗部
２２ めっき処理部
２２ａ 第１のめっき処理部
２２ｂ 第２のめっき処理部
２４，２６，２８ 搬送装置
４５ めっき液
４６ めっき処理槽
４７ ヘッド部
４８ アノード
４９ めっき室
５０ めっき槽
５３ めっき液噴出ノズル
５５ めっき液供給管
５７，５９，１２０ めっき液排出口
５８ 堰部材
６２ 鉛直整流リング
６３ 水平整流リング
７０ ハウジング
７２ 基板保持部
７５ 空気抜き穴
７６ カソード電極用接点
７７ 給電接点
２４０ 押圧リング
２４２ 押圧ロッド
２４４ シール材
２７０ 芯出し機構
２７２ ブラケット
２７４ ブロック
２７６ 枢軸[0001]
BACKGROUND OF THE INVENTION
  The present invention, MeMethodas well asIt relates to plating equipment, and is used to form copper wiring by embedding copper by plating in a fine recess for wiring formed on the surface of a semiconductor substrate.RumeMethodas well asThe present invention relates to a plating apparatus.
[0002]
[Prior art]
In recent years, as a metal material for forming a wiring circuit on a semiconductor substrate, a movement of using copper (Cu) having a low electrical resistivity and a high electromigration resistance instead of aluminum or an aluminum alloy has become prominent. This type of copper wiring is generally formed by embedding copper in a fine recess provided on the surface of the substrate. As a method of forming this copper wiring, there are methods such as CVD, sputtering, and plating. In any case, copper is formed on almost the entire surface of the substrate, and unnecessary copper is formed by chemical mechanical polishing (CMP). To be removed.
[0003]
FIG. 39 shows a manufacturing example of this type of copper wiring board W in the order of steps. As shown in FIG. 39 (a), SiO is formed on the conductive layer 1a on the semiconductor substrate 1 on which the semiconductor elements are formed.₂An oxide film 2 is deposited, a contact hole 3 and a wiring groove 4 are formed by lithography / etching technique, a barrier layer 5 made of TaN or the like is formed thereon, and a seed layer is formed thereon as a power feeding layer for electrolytic plating. 7 is formed.
[0004]
Then, as shown in FIG. 39B, the contact hole 3 and the groove 4 of the semiconductor substrate 1 are filled with copper by performing copper plating on the surface of the substrate W, and a copper film is formed on the oxide film 2. 6 is deposited. Thereafter, the copper film 6 on the oxide film 2 is removed by chemical mechanical polishing (CMP), and the surface of the copper film 6 filled in the contact hole 3 and the wiring groove 4 and the surface of the oxide film 2 Are almost coplanar. As a result, a wiring made of the copper film 6 is formed as shown in FIG.
[0005]
Here, the seed layer 7 is generally formed by sputtering or CVD. In addition, in electrolytic copper plating for forming the copper film 6, a copper sulfate plating solution containing copper sulfate and sulfuric acid in its composition is used as a plating solution. Generally used.
[0006]
[Problems to be solved by the invention]
As fine wiring progresses and the shape of the wiring groove or plug becomes a high aspect ratio, the seed layer formed by sputtering or the like does not reach the bottom of the groove uniformly, and as shown in FIG. Film thickness t of seed layer 7 on the side wall₁Is the film thickness t near the substrate surface₂May be 1/10 or less than that. When copper is embedded by electrolytic copper plating using a copper sulfate plating solution in such a state, it becomes difficult for current to flow in an extremely thin portion of the seed layer 7, as shown in FIG. In the copper film 6, unplated portions (voids) 8 are formed. In order to prevent this, if the seed layer 7 is made thick to form a uniform film at the bottom of the groove, the copper will be thick at the inlet of the groove, resulting in the closing of the inlet first. Create a void.
[0007]
On the other hand, copper plating solutions have been developed in which a complexing agent and a pH adjusting agent are attached to a base such as copper sulfate so that the pH is maintained in the vicinity of neutrality. However, these copper plating solutions are stable. In addition to being impractical and impractical, this pH adjuster generally contains an alkali metal such as sodium or potassium. If a plating solution mixed with such an alkali metal is used in the semiconductor field, electromigration can be prevented. Cause the semiconductor to deteriorate. Although there are copper cyanide-based copper plating solutions, cyan is harmful to the human body, and therefore it is required to avoid its use from the viewpoint of work and environment.
[0008]
  The present invention has been made in view of the above circumstances, and does not contain alkali metal or cyan, but reinforces the thin portion of the seed layer, or copper plating that reliably embeds copper inside the fine recess of high aspect ratio Copper plating that can be appliedLiquidPlating method usedas well asAn object is to provide a plating apparatus.
[0009]
[Means for Solving the Problems]
  The invention described in claim 1In a plating method of plating a substrate having a fine depression covered with a seed layer and filling the fine depression with a metal, the substrate is mixed with a divalent copper ion having a concentration of 1 to 10 g / L and a complexing agent. A first plating process that reinforces the seed layer by immersing it in a first plating solution that is made of a substance that does not contain alkali metal and cyanide and has a polarization greater than that of the second plating solution described below. Thereafter, the substrate is immersed in a second plating solution, and a second stage plating process is performed in which copper is embedded in the fine recesses.It is characterized byPlating methodIt is. Thus, by having a complexing agent in the copper plating solution, it is possible to increase the polarization as a plating bath and improve the throwing power, thereby reinforcing the thin portion of the seed layer and increasing the high aspect ratio. It is possible to bury copper uniformly in the depth of a fine recess such as a trench or a hole. In addition, the deposited plating is dense and the danger of microvoids can be avoided. Furthermore, since alkali metal and cyan are not included, it is possible to prevent the semiconductor from being deteriorated by electromigration due to the presence of the alkali metal and to meet the demand for avoiding the use of cyan.
[0010]
Here, when the concentration of the divalent copper ions is low, the current efficiency is deteriorated and the copper deposition efficiency is lowered, and when it is high, the electrodeposition property is deteriorated. Therefore, about 0.1 to 100 g / L is preferable. About 10 g / L is more preferable. On the other hand, if the concentration of the complexing agent is low, copper complexation is not complete and precipitation is likely to occur. If the concentration is high, not only the appearance of burnt plating is deteriorated but also the appearance is deteriorated, and wastewater treatment is difficult. About -500 g / L is preferable and about 20-200 g / L is more preferable.
[0011]
  The invention according to claim 2 is characterized in that the complexing agent is ethylenediaminetetraacetic acid, ethylenediamine, N, N ′, N ″, N ″ ′ ethylenedinitrotetrapropan-2-ol, pyrophosphoric acid, iminodiacetic acid, diethylenetriamine. Must be pentaacetic acid, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, diaminobutane, hydroxyethylethylenediamine, ethylenediaminetetrapropionic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid or their derivatives. The claim according to claim 1Plating methodIt is.
[0012]
  The invention according to claim 3The first plating solution is used as a pH adjuster.ReNmaOr tetramethylammonium hydroxideTheThe plating method according to claim 1 or 2, further comprising: In this way, by adding a pH adjusting agent as necessary, the plating solution is adjusted to pH 7 to 14, preferably pH 8 to 11, more preferably about pH 8 to 9, so that the pH is too low and the complex becomes effective. It is possible to prevent imperfection without tying, or conversely, too high of the complex to form another precipitate.
[0013]
  The invention according to claim 4The concentration of the complexing agent in the first plating solution is 20 to 200 g / L.It is characterized byClaim 1This is a plating method.
[0014]
  According to the plating method of the present invention,For example, even if the seed layer has a thin portion, the thin portion is reinforced by the first-stage plating process, and the second-stage plating process uses the complete seed layer as a power supply layer. A plating film having a flat surface can be formed while embedding a metal such as copper inside.
[0015]
  The invention according to claim 5,Substrate having a fine depression covered with a cathode layerThe first plating having a concentration of 1 to 10 g / L of divalent copper ions and a complexing agent and containing no alkali metal and cyanide, and having a higher polarization than the following second plating solution Reinforce the seed layer by dipping in a liquidFirst stage plating processDoA first plating section;SaidA first plating solution supply means for supplying a first plating solution to the plating tank of the first plating processing unit;The substrate in which the seed layer is reinforced by the first-stage plating treatment is immersed in a second plating solution, and copper is embedded in the fine recess.Second stage plating processDoA second plating section;SaidA second plating solution supply means for supplying a second plating solution to the plating tank of the second plating processing unit;SaidTransport means for transporting the substrate from the first plating processing section to the second plating processing section.To doThe plating apparatus characterized by these.
  The invention according to claim 6 is the plating apparatus according to claim 5, wherein the concentration of the complexing agent in the first plating solution is 20 to 200 g / L.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a plan layout view of a plating apparatus according to an embodiment of the present invention. The plating apparatus includes a load / unload unit 10, a pair of cleaning / drying processing units 12, a first substrate stage 14, a bevel etch / chemical solution cleaning unit 16 and a second substrate stage 18, and a function of inverting the substrate by 180 °. It has a water washing section 20 and four plating processing sections 22. Further, a first transfer device 24 that transfers substrates between the load / unload unit 10, the cleaning / drying processing unit 12, and the first substrate stage 14, a first substrate stage 14, a bevel etch / chemical solution cleaning unit 16, and A second transfer device 26 that transfers substrates between the second substrate stages 18 and a third transfer device 28 that transfers substrates between the second substrate stage 18, the water washing unit 20, and the plating unit 22 are provided. ing.
[0017]
The interior of the plating apparatus is partitioned into a plating space 712 and a clean space 713 by a partition wall 711, and each of the plating space 712 and the clean space 713 can be independently supplied and exhausted. The partition wall 711 is provided with an openable / closable shutter (not shown). The pressure in the clean space 713 is lower than the atmospheric pressure and higher than the pressure in the plating space 712, so that the air in the clean space 713 does not flow out of the plating apparatus and the plating space. The air in 712 does not flow into the clean space 713.
[0018]
FIG. 2 shows the flow of airflow in the plating apparatus. In the clean space 713, fresh external air is taken in from the pipe 730. This external air is pushed into the clean space 713 through the high-performance filter 731 by the fan, and cleaned and dried as downflow clean air from the ceiling 732a. Supplied around the processing unit 12 and the bevel etch / chemical solution cleaning unit 16. Most of the supplied clean air is returned from the floor 732b to the ceiling 732a through the circulation pipe 733, and is again pushed into the clean space 713 by the fan through the high-performance filter 731 and circulates in the clean space 713. A part of the airflow is exhausted to the outside through the pipe 734 from the cleaning / drying processing unit 12 and the bevel etch / chemical solution processing unit 16. Thereby, the inside of the clean space 713 is set to a pressure lower than the atmospheric pressure.
[0019]
The plating space 712 in which the water washing unit 20 and the plating processing unit 22 exist is not a clean space (contamination zone), but particles are not allowed to adhere to the substrate surface. For this reason, particles are prevented from adhering to the substrate by flowing down-flow clean air that is taken in from the pipe 735 and pushed into the plating space 712 by the fan from the ceiling 737a side through the high-performance filter 736. . However, if the total flow rate of the clean air that forms the downflow depends on the supply and exhaust from the outside, a huge amount of supply and exhaust is required. For this reason, the outside of the pipe 738 is exhausted to the extent that the inside of the plating space 712 is kept at a lower pressure than the clean space 713, so that the majority of the downflow airflow is covered by the circulating airflow through the circulation pipe 739 extending from the floor 737b. ing.
[0020]
As a result, the air returned from the circulation pipe 739 to the ceiling 737a side is pushed again by the fan, supplied through the high-performance filter 736 as clean air into the plating space 712, and circulates. Here, air containing chemical mist and gas from the water washing section 20, the plating processing section 22, the conveying device 28, and the plating solution adjustment tank 740 is discharged to the outside through the pipe 738, and the inside of the plating space 712 is a clean space. The pressure is set lower than 713.
[0021]
As shown in FIG. 3, the plating processing unit 22 has a substantially cylindrical shape and a plating processing tank 46 that contains a plating solution 45 therein, and a head unit that is disposed above the plating processing tank 46 and holds the substrate W. 47. FIG. 3 shows a state where the substrate W is held by the head portion 47 and the plating surface is in the plating position where the liquid level of the plating solution 45 is raised.
[0022]
The plating tank 46 includes a plating chamber 49 that is open upward and has an anode 48 disposed at the bottom, and a plating tank 50 that holds a plating solution 45 is provided in the plating chamber 49. On the inner peripheral wall of the plating tank 50, plating solution jet nozzles 53 that protrude horizontally toward the center of the plating chamber 49 are arranged at equal intervals along the circumferential direction. The interior of 50 communicates with a plating solution supply path extending vertically.
[0023]
This plating solution supply path is connected to a plating solution adjustment tank 40 via a plating solution supply pipe 55 shown in FIG. 4, and a control valve that controls the secondary side pressure constant in the middle of this plating solution supply pipe 55. 56 is interposed.
[0024]
Further, in this example, a punch plate 220 having a large number of holes of about 3 mm, for example, is disposed above the anode 48 in the plating chamber 49, whereby the black film formed on the surface of the anode 48 is plated. It is wound up by the liquid 45 and is prevented from flowing out.
[0025]
Further, the plating tank 50 overflows the first plating solution discharge port 57 through which the plating solution 45 in the plating chamber 49 is drawn out from the peripheral edge of the bottom of the plating chamber 49 and the weir member 58 provided at the upper end of the plating bath 50. A second plating solution discharge port 59 for discharging the plating solution 45 and a third plating solution discharge port 120 for discharging the plating solution 45 before overflowing the weir member 58 are provided. The plating solutions flowing through the second plating solution outlet 59 and the third plating solution outlet 120 are discharged together at the lower end of the plating tank. Instead of providing the third plating solution discharge port 120, as shown in FIG. 9, openings 222 having a predetermined width are provided at predetermined intervals at the lower portion of the dam member 58, and the plating solution that has passed through the openings 222 is subjected to the second plating. You may make it discharge | emit to the liquid discharge port 59. FIG.
[0026]
As a result, when the plating amount is large during the plating process, the plating solution is discharged to the outside from the third plating solution discharge port 120, or is passed through the opening 222 and externally from the second plating solution discharge port 59. At the same time, as shown in FIG. 9A, the weir member 58 is overflowed and discharged from the second plating solution discharge port 59 to the outside. Further, when the plating amount is small during the plating process, instead of discharging the plating solution from the third plating solution outlet 120 or providing the third plating solution outlet 120, FIG. 9B. As shown in FIG. 5, the opening 222 is passed through and discharged from the second plating solution discharge port 59 to the outside, thereby easily dealing with the amount of plating.
[0027]
Further, as shown in FIG. 9 (d), a liquid level control through hole 224 that communicates with the plating chamber 49 and the second plating solution discharge port 59 is located above the plating solution ejection nozzle 53. The plating solution is provided at a predetermined pitch along the direction, and thereby the plating solution passes through the through-hole 224 and is discharged to the outside from the second plating solution discharge port 59 during non-plating, thereby controlling the liquid level of the plating solution. It has become. The through hole 224 plays a role like an orifice during the plating process, and the amount of the plating solution flowing out of the through hole 224 is limited.
[0028]
As shown in FIG. 4, the first plating solution discharge port 57 is connected to the reservoir 226 via a plating solution discharge pipe 60a, and a flow rate regulator 61a is interposed in the middle of the plating solution discharge pipe 60a. The second plating solution discharge port 59 and the third plating solution discharge port 120 join in the plating tank 50 and then are directly connected to the reservoir 226 through the plating solution discharge pipe 60b.
[0029]
The plating solution that has entered the reservoir 226 enters the plating solution adjustment tank 40 from the reservoir 226 by the pump 228. The plating solution adjustment tank 40 is provided with a temperature controller 230 and a plating solution analysis unit 232 for taking out and analyzing the sample solution. When the pump 234 is driven, the plating solution adjustment tank 40 passes through the filter 236. The plating solution 45 is supplied to the plating solution ejection nozzle 53 of the plating processing unit 22. A control valve 56 is provided in the middle of the plating solution supply pipe 55 extending from the plating solution adjustment tank 40 to the plating processing unit 22 to keep the secondary pressure constant.
[0030]
Returning to FIG. 3, the central portion of the plating solution surface is pushed upward by the upper flow divided into the upper and lower portions of the plating solution 45 in the plating chamber 49, located in the vicinity of the periphery inside the plating chamber 49, and downward. The vertical rectification ring 62 and the horizontal rectification ring 63 that make the flow of the current smooth and the current density distribution more uniform are arranged with the outer peripheral end of the horizontal rectification ring 63 fixed to the plating tank 50. .
[0031]
On the other hand, the head portion 47 is provided with a housing 70 having a bottomed cylindrical shape that opens freely and has an opening 96 in the peripheral wall, and a pressing rod 242 that can be moved up and down with a pressing ring 240 attached to its lower end. . As shown in FIG. 8, a ring-shaped substrate holding portion 72 that protrudes inward is provided at the lower end of the housing 70. The substrate holding portion 72 protrudes inward, and the tip of the upper surface is shaped like a spire. A ring-shaped sealing material 244 is attached to the projection. Further, a cathode electrode contact 76 is disposed above the sealing material 244. Further, the substrate holding part 72 is provided with air vent holes 75 extending outward in the horizontal direction and further inclined upward and extending outward in the circumferential direction at equal intervals.
[0032]
Accordingly, as shown in FIG. 6, the substrate W is held by the suction hand H or the like and placed inside the housing 70 with the liquid level of the plating solution 45 lowered as shown in FIGS. 7 and 8. After placing the suction hand H on the upper surface of the sealing material 244 of the substrate holding part 72 and pulling out the suction hand H from the housing 70, the pressing ring 240 is lowered, so that the peripheral portion of the substrate W is placed on the lower surfaces of the sealing material 244 and the pressing ring 240. And holding the substrate W, and when the substrate W is held, the lower surface of the substrate W and the sealing material 244 are pressed against each other to securely seal the substrate W, and at the same time, the substrate W and the cathode electrode contact 76 are energized. It is supposed to do.
[0033]
Returning to FIG. 3, the housing 70 is connected to the output shaft 248 of the motor 246 and is configured to rotate by driving of the motor 246. The pressing rod 242 is formed by a ring-shaped support frame 258 that is rotatably supported via a bearing 256 at the lower end of a slider 254 that moves up and down by operation of a guide cylinder 252 fixed to a support body 250 that surrounds the motor 246. It is vertically suspended at a predetermined position along the circumferential direction, so that it moves up and down by the operation of the cylinder 252 and rotates integrally with the housing 70 when the substrate W is held.
[0034]
The support body 250 is attached to a slide base 262 that is engaged with a ball screw 261 that rotates as the motor 260 is driven and moves up and down, and is further surrounded by an upper housing 264. It moves up and down together with the housing 264. A lower housing 266 that surrounds the periphery of the housing 70 during the plating process is attached to the upper surface of the plating tank 50.
[0035]
As a result, as shown in FIG. 6, maintenance can be performed with the support body 250 and the upper housing 264 raised. Further, although the crystal of the plating solution is likely to adhere to the inner peripheral surface of the weir member 58, a large amount of the plating solution is flowed in a state where the support body 250 and the upper housing 264 are lifted, so that the weir member 58 is By making it overflow, adhesion of the crystal | crystallization of the plating solution to the inner peripheral surface of the dam member 58 can be prevented. In addition, the plating tank 50 is integrally provided with a plating solution scattering prevention cover 50b that covers the upper part of the plating solution that overflows during the plating process. On the lower surface of the plating solution scattering prevention cover 50b, for example, HIREC (NTT Advance) is provided. By coating a super-water-repellent material such as Technology), it is possible to prevent the plating solution crystals from adhering thereto.
[0036]
Substrate centering mechanisms 270 that center the substrate W are provided above the substrate holding portion 72 of the housing 70 in this example at four locations along the circumferential direction. FIG. 10 shows details of the board centering mechanism 270, which includes a portal bracket 272 fixed to the housing 70 and a positioning block 274 disposed in the bracket 272. The upper portion 274 is swingably supported via a pivot 276 fixed to the bracket 272 in the horizontal direction, and a compression coil spring 278 is interposed between the housing 70 and the positioning block 274. As a result, the positioning block 274 is biased through the compression coil spring 278 so that the lower portion projects inwardly about the pivot 276, and the upper surface 274 a serves as a stopper and acts on the upper lower surface 272 a of the bracket 272. By abutting, the movement of the positioning block 274 is regulated. Furthermore, the inner surface of the positioning block 274 is a tapered surface 274b that extends outwardly upward.
[0037]
Thus, for example, when the substrate is held by a suction hand such as a transfer robot, transferred into the housing 70 and placed on the substrate holding portion 72, the substrate is compressed if the center of the substrate is deviated from the center of the substrate holding portion 72. When the positioning block 274 rotates outwardly against the elastic force of the coil spring 278 and the gripping by the suction hand such as the transfer robot is released, the positioning block 274 returns to the original position by the elastic force of the compression coil spring 278. By doing so, the substrate can be centered.
[0038]
FIG. 11 shows a power supply contact (probe) 77 for supplying power to the cathode electrode plate 208 of the cathode electrode contact 76. The power supply contact 77 is formed of a plunger and has a cylindrical shape reaching the cathode electrode plate 208. The protective body 280 is surrounded and protected from the plating solution.
[0039]
Next, the plating process by this plating process part 22 is demonstrated.
First, when the substrate is delivered to the plating unit 22, the suction hand of the third transport device 28 shown in FIG. 1 and the substrate W sucked and held by the hand with the surface facing downward are opened from the opening 96 of the housing 70 to the inside. After the suction hand is moved downward, the vacuum suction is released, the substrate W is placed on the substrate holding part 72 of the housing 70, and then the suction hand is raised and pulled out of the housing 70. . Next, the pressing ring 240 is lowered, and the substrate W is held by holding the peripheral edge portion of the substrate W between the substrate holding portion 72 and the lower surface of the pressing ring 240.
[0040]
Then, the plating solution 45 is ejected from the plating solution ejection nozzle 53, and at the same time, the housing 70 and the substrate W held thereon are rotated at a medium speed. When the plating solution 45 is filled up to a predetermined amount and a few seconds have passed, The housing 70 is rotated at a low speed (for example, 100 min.^-1Then, electrolytic plating is performed by passing a plating current using the anode 48 as an anode and the substrate processing surface as a cathode.
[0041]
After the energization is finished, as shown in FIG. 9D, the supply amount of the plating solution so that the plating solution flows out only from the liquid level control through-hole 224 located above the plating solution ejection nozzle 53. Thus, the housing 70 and the substrate W held by the housing 70 are exposed on the plating solution surface. At a position where the housing 70 and the substrate W held by the housing 70 are above the liquid level, high speed (for example, 500 to 800 min)^-1) To remove the plating solution by centrifugal force. After the draining is completed, the rotation of the housing 70 is stopped so that the housing 70 faces a predetermined direction.
[0042]
After the housing 70 is completely stopped, the pressing ring 240 is raised. Next, the suction hand of the third transport device 28 is inserted into the inside through the opening 96 of the housing 70 with the suction surface facing downward, and the suction hand is lowered to a position where the suction hand can suck the substrate. Then, the substrate is vacuum-sucked by the suction hand, the suction hand is moved to a position above the opening 96 of the housing 70, and the suction hand and the substrate held by the suction hand are taken out from the opening 96 of the housing 70.
[0043]
According to the plating processing unit 22, the mechanical simplification and compactness of the head unit 47 are achieved, and when the plating solution level in the plating processing tank 46 is at the plating level, the plating treatment is transferred to the substrate. When the liquid level is reached, draining and delivery of the substrate can be performed, and drying and oxidation of the black film formed on the surface of the anode 48 can be prevented.
[0044]
FIG. 12 is a schematic diagram showing the cleaning / drying processing unit 12. In the cleaning / drying processing unit 12, the front and back surfaces of the semiconductor substrate W are scrubbed with PVA sponge rolls 9-2 and 9-2. The cleaning water ejected from the nozzle 9-4 is mainly pure water, but the pH is adjusted after mixing the surfactant, chelating agent or both, and the one adjusted to the zeta potential of copper oxide is used. Also good. Moreover, the ultrasonic vibration element 9-3 may be provided in the nozzle 9-4, and ultrasonic vibration may be applied to the jetted cleaning water. Reference numeral 9-1 denotes a rotating roller for rotating the semiconductor substrate W in a horizontal plane.
[0045]
The bevel etch / chemical solution cleaning unit 16 can perform edge (bevel) Cu etching and back surface cleaning at the same time, and can suppress the growth of a natural oxide film of copper in the circuit forming unit on the substrate surface. FIG. 13 shows an outline of the bevel etch / chemical solution cleaning unit 16. As shown in FIG. 13, the bevel etch / chemical solution cleaning unit 16 is positioned inside a bottomed cylindrical waterproof cover 420 and spins the substrate W face-up at a plurality of locations along the circumferential direction of the peripheral portion. A substrate holding unit 422 that is horizontally held by the chuck 421 and rotated at a high speed, a center nozzle 424 disposed almost at the center on the surface side of the substrate W held by the substrate holding unit 422, and a peripheral portion of the substrate W And an edge nozzle 426 disposed above. The center nozzle 424 and the edge nozzle 426 are disposed downward. In addition, a back nozzle 428 is disposed upward and positioned substantially below the center of the back side of the substrate W. The edge nozzle 426 is configured to be movable in the diameter direction and the height direction of the substrate W.
[0046]
The movement width L of the edge nozzle 426 can be arbitrarily positioned from the outer peripheral end surface of the substrate toward the center, and a set value is input in accordance with the size of the substrate W and the purpose of use. Usually, the edge cut width C is set in the range of 2 mm to 5 mm, and the copper film within the set cut width C is removed if the amount of liquid flowing from the back surface to the front surface is not a problem. be able to.
[0047]
Next, a processing method by the bevel etch / chemical solution cleaning unit 16 will be described. First, the semiconductor substrate W is horizontally rotated integrally with the substrate holding unit 422 while the substrate is held horizontally by the substrate holding unit 422 via the spin chuck 421. In this state, the acid solution is supplied from the center nozzle 424 to the central portion on the surface side of the substrate W. The acid solution may be any non-oxidizing acid such as hydrofluoric acid, hydrochloric acid, sulfuric acid, citric acid, or succinic acid. On the other hand, an oxidant solution is continuously or intermittently supplied from the edge nozzle 426 to the peripheral edge of the substrate W. As the oxidant solution, ozone water, hydrogen peroxide water, nitric acid water, sodium hypochlorite water, or the like is used, or a combination thereof is used.
[0048]
As a result, in the region of the peripheral portion C of the semiconductor substrate W, the copper film or the like formed on the upper surface and the end surface is rapidly oxidized with the oxidant solution, and simultaneously supplied from the center nozzle 424 and spreads over the entire surface of the substrate. Is removed by etching. In this way, by mixing the acid solution and the oxidant solution at the peripheral edge of the substrate, a steeper etching profile can be obtained as compared to supplying the mixed water from the nozzle in advance. At this time, the etching rate of copper is determined by their concentration. Further, when a copper natural oxide film is formed on the circuit forming portion on the surface of the substrate, the natural oxide is immediately removed by an acid solution that spreads over the entire surface of the substrate as the substrate rotates, and grows. There is nothing.
[0049]
That is, by flowing HF from the surface, copper oxide on the surface formed at the time of plating can be removed, and no oxide film is formed during etching. If there is a copper oxide film on the surface of the semiconductor substrate, only the copper oxide portion will be polished first during CMP, which adversely affects the flatness of the surface after CMP. Such an adverse effect can be avoided by removing the film.
[0050]
Note that after the supply of the acid solution from the center nozzle 424 is stopped, the supply of the oxidant solution from the edge nozzle 426 is stopped to oxidize silicon exposed on the surface and suppress the adhesion of copper. be able to.
[0051]
That is, for example, in the case of a substrate where an active surface such as Si is exposed, H₂O₂By stopping the process later and oxidizing and inactivating the surface, it is possible to prevent adsorption of large particles that cause scratches in subsequent CMP. Thus, H₂O₂By repeating the step of oxidizing copper with HF and removing the oxidized copper with HF, the copper removal rate can be improved as compared with the case where copper is oxidized and removed simultaneously using a mixed solution. it can.
[0052]
On the other hand, an oxidant solution and a silicon oxide film etchant are supplied simultaneously or alternately from the back nozzle 428 to the center of the back surface of the substrate. As a result, copper or the like adhering to the back surface side of the semiconductor substrate W can be removed by oxidizing the silicon on the substrate together with the oxidant solution and etching with the silicon oxide film etchant. It is preferable to use the same oxidant solution as the oxidant solution supplied to the surface in order to reduce the types of chemicals. Also, hydrofluoric acid can be used as the silicon oxide film etchant, and the number of chemicals can be reduced if hydrofluoric acid is used for the acid solution on the surface side of the substrate.
[0053]
As a result, a hydrophobic surface is obtained if the oxidant supply is stopped first, and a saturated surface (hydrophilic surface) is obtained if the etchant solution is stopped first, and the back surface is adjusted according to the requirements of the subsequent process. You can also. After supplying the acid solution, that is, the etching solution to the substrate in this way to remove the metal ions remaining on the surface of the substrate W, the pure water is further supplied to perform pure water replacement, and then the etching solution is removed. Spin drying. In this way, the removal of the copper film within the edge cut width C at the peripheral edge portion of the semiconductor substrate surface and the removal of copper contamination on the back surface can be simultaneously performed, and this process can be completed within 80 seconds, for example. Note that the etching cut width of the edge can be arbitrarily set (2 mm to 5 mm), but the time required for etching does not depend on the cut width.
[0054]
FIGS. 14 to 17 show an optimum substrate rotating apparatus 440 used in the cleaning / drying processing unit 12 and the bevel etch / chemical solution cleaning unit 16. The substrate rotating device 440 is for holding and rotating the substrate W horizontally. The substrate rotating device 440 is set horizontally and rotates a disk-shaped rotating member 444 that is rotated by a rotation drive shaft 442 and the substrate W. And a plurality of holding members 446 for holding on the member 444. The holding member 446 is provided at the outer peripheral edge portion of the rotating member 444 at a predetermined interval (60 ° in the illustrated example) along a circle centered on the rotational drive shaft 442, and the peripheral edge W ′ of the substrate W. The substrate W is held horizontally by engaging with. In FIG. 14, reference numeral 447 is a belt drive device for drivingly connecting the rotation drive shaft 442 and the motor M, and H is a housing for housing the rotation holding device 440 and is supplied onto the substrate W by the nozzle N. The cleaning liquid or the like collected is prevented from being scattered around and is discharged from the discharge pipe D.
[0055]
FIG. 16 shows details of the holding member 446. That is, the holding member 446 has a substantially cylindrical shape, and has an engagement peripheral surface 448 formed like an annular groove near the top end of the holding member 446. The engagement peripheral surface 448 is configured to frictionally engage with the peripheral edge W ′ of the substrate W. The holding member 446 vertically penetrates a slot 450 formed to extend in the radial direction in the outer peripheral edge portion of the rotating member 444, and a lower end thereof extends below the rotating member 444 so as to be integrated with the rotating member 444. It is rotatably supported by a holding plate 452 configured to rotate. Accordingly, the holding member 446 is held so as to be rotatable about its axis. That is, the holding plate 452 has a small-diameter shaft 454 that extends vertically upward. On the other hand, a hole 456 that extends upward from the lower end of the holding member 446 is formed, and the hole 456 has a small-diameter shaft 454. The holding member 446 rotates about the small-diameter shaft 454.
[0056]
Further, a weight 458 is fixed to the lower end of the holding member 446 and extends in the horizontal direction, and the rotating member 444 is rotated so that the holding member 446 is centered on the rotation axis of the rotating member 444 (that is, the rotation drive shaft 442). When the shaft is rotated (revolved), a centrifugal force acts on the weight 458, whereby the holding member 446 rotates (rotates) around its axis. The position of the weight 458 indicated by the solid line in FIG. 17 is the home position, and is pressed against this position by elastic means (not shown). When a predetermined centrifugal force is applied, the weight 458 is directed toward the position indicated by the alternate long and short dash line. The substrate W moves in the direction of arrow A, and accordingly, the substrate W is rotated in the direction of arrow B.
[0057]
The holding plate 452 is supported by a link mechanism (not shown) so as to be horizontally movable along the slot 450 in the radial direction C of the rotating member 444, and the holding plate 452 is supported at the periphery of the substrate W. It is possible to move between an engagement holding position that engages W ′ (the position in FIG. 16) and a disengagement position that is located radially outward from the engagement holding position and is away from the peripheral edge W ′ of the substrate W. . The holding plate 452 is biased by the spring 460 toward the inner side in the radial direction of the rotating member 444, and the engagement peripheral surface 448 of the holding member 446 in the engagement holding position is elastic through the spring 460. Are engaged with a peripheral edge W ′ of the substrate W.
[0058]
In order to hold and rotate the substrate W by the rotation holding device 440, first, the holding member 446 is moved to the disengagement position radially outside the rotation member 444 against the biasing force of the spring 460. In this state, the substrate W is set horizontally above the rotation member 444, the holding member 446 is returned to the engagement position, the engagement peripheral surface 448 is engaged with the peripheral edge W ′ of the substrate W, and the substrate W is Hold elastically.
[0059]
When the rotating member 444 is rotationally driven and the holding member 446 performs a revolving motion, a centrifugal force acts on the weight 458. When the rotation speed of the rotating member 444 is low, the centrifugal force acting on the weight 458 is small, and the weight 458 is held in an unswinged state by the spring pressure pressing the holding member 446 to the home position. However, when the rotational speed of the rotating member 444 exceeds a predetermined value, the centrifugal force acting on the weight 458 resists the pressure of the spring and the weight 458 swings, whereby the holding member 446 is centered on its axis. Rotate (spin). As described above, since the holding member 446 is frictionally engaged with the peripheral edge W ′ of the substrate W, when the holding member 446 is rotated, the substrate W is rotated in the direction of arrow B in FIG. The engagement position of the peripheral edge W ′ of the substrate W with the holding member 446 changes.
[0060]
In the illustrated example, a weight 458 having a center of gravity is attached to the holding member 446 at a position eccentric from the axis of the holding member 446, so that the holding member 446 has its axis centered with the rotation of the rotating member 444. Although an example of rotating (spinning) to the center is shown, the rotation (spinning) of the holding member 446 is not necessarily limited to this, and for example, a certain link mechanism is connected to the holding member 446. In addition, the holding member 446 may be rotated (rotated) by operating the link mechanism.
[0061]
The rotation holding device 440 has the above-described configuration and operation. For example, when the substrate W is held and rotated by the rotation holding device 440 when the substrate W is cleaned, the rotation holding device 440 Since the engagement position between the substrate W and the holding member 446 can be changed during the cleaning process, the cleaning liquid or the like used for the cleaning process of the substrate W can be distributed to all the peripheral portions of the substrate W. Appropriate processing becomes possible.
[0062]
The rotation holding device 440 can be applied to all cleaning devices, but is optimal for the bevel etch / chemical solution cleaning unit 16. That is, when applied to the bevel etch / chemical solution cleaning unit 16, the substrate W is securely held, and the edge or bevel of the substrate W is changed by changing the engagement position between the edge (periphery W ′) of the substrate and the holding member 446. Etching can be performed without leaving a part.
[0063]
FIG. 18 is a diagram illustrating a configuration example of the transporting device 26 and a dry state film thickness measuring machine 413 provided in the hand of the transporting device 26. FIG. 18A is a view showing the appearance of the transfer device 26, and FIG. 18B and FIG. 18C are a plan view and a sectional view of the robot hand, respectively. As shown in the figure, the transport device 26 has two hands 3-1 and 3-1 on the upper and lower sides, and the hands 3-1 and 3-1 are respectively attached to the tips of the arms 3-2 and 3-2. It can be swiveled. The hands 3-1 and 3-1 can scoop up the semiconductor substrate W (drop the semiconductor substrate W into the recess) and transfer it to a predetermined location.
[0064]
A plurality of eddy current sensors 413a (four in the figure) constituting the dry state film thickness measuring device 413 are provided on the dropping surface of the semiconductor substrate W of the hand 3-1, and the film thickness of the semiconductor substrate W placed thereon is provided. Can be measured.
[0065]
  Thus, the dry state film thickness measuring machine is provided in the transport device 26.413By attaching, the film thickness can be measured on the robot hands 3-1 and 3-1. Then, it is possible to leave this film thickness measurement result as a processing record of the semiconductor substrate W or to determine whether it can be taken to the next step based on this result. The transport device 28 has the same configuration as the transport device 26, and a dry state film thickness measuring device is provided on the transport device 28 side.413May be attached.
[0066]
Next, the plating method of the present invention will be described with reference to FIG. In this example, one of the four plating processing units 22 shown in FIG. 1 is used as the first plating processing unit 22a for the first stage plating process, and the other three units are used for the second stage plating process. By using as the second plating portion 22b, the thin portion of the seed layer 7 shown in FIG. 40 (a) is reinforced by the first step plating treatment by the first plating portion 22a, and the complete portion without the thin portion In such a reinforced state, the second plating process by the second plating part 22b, that is, the copper embedding is performed.
[0067]
Here, in the 1st plating process part 22a, it has a bivalent copper ion, a complexing agent, and a pH adjuster as the plating solution 45 (refer FIG. 3), alkali metal and cyanide metal are included. A plating solution that does not contain, for example, a plating solution (first plating solution) excellent in uniform conductivity made of copper pyrophosphate, pyrophosphoric acid and choline is used. The first plating solution is adjusted to pH 7 to 14, preferably pH 8 to 11, more preferably about pH 8 to 9 by adding a pH adjusting agent such as choline, so that the complex is effective because the pH is too low. Although it is incomplete without being connected, or on the contrary, it is too high to prevent the complex from being formed in a different form and a precipitate is formed, but a pH adjusting agent is not always necessary. This divalent copper ion can be obtained, for example, by dissolving copper salts such as copper pyrophosphate, copper sulfate, copper acetate, copper chloride, EDTA-Cu, copper carbonate, copper nitrate, copper sulfamate.
In the 2nd plating process part 22b, the copper sulfate plating solution (2nd plating solution) excellent in the leveling property which contains copper sulfate and a sulfuric acid in the composition is used as the plating solution 45 (refer FIG. 3). is doing.
[0068]
First, the substrate W on which the seed layer 7 (see FIG. 39A) is formed is taken out from the loading / unloading unit 10 one by one by the first transfer device 24, and the first substrate stage 14 and the second substrate stage 18 are removed. Then, it is carried into the first plating processing part 22a via (step 1).
[0069]
Next, the first plating process using the first plating solution is performed in the first plating process part 22a to reinforce the thin part of the seed layer 7 and complete it (step 2). In other words, the first plating solution used in the first plating processing unit 22a is based on, for example, copper pyrophosphate, and a complexing agent such as pyrophosphoric acid is added thereto. Polarization is higher than that of the solution (second plating solution). Here, high polarization means that the ratio of the change in voltage to the change in current density is large, that is, the fluctuation in current density is small with respect to potential fluctuation. For example, when comparing bath A and bath B having the negative polarization curve shown in FIG. 20, b / (D in bath B₂-D₁) Is a / (D in A bath₂-D₁) Is larger than that of the A bath. As a result, even if there is a difference in the film thickness of the seed layer 7 and a potential difference occurs during energization, fluctuations in current density can be reduced. For this reason, the deposition potential is raised, the uniformity of electrodeposition is improved, and the plating is deposited even on a thin portion of the seed layer, which is difficult to deposit with a normal copper sulfate plating solution.
Here, since the alkali metal is not contained in the complex itself or the pH adjuster, the alkali metal is not taken into the film and the semiconductor characteristics are not deteriorated.
[0070]
As the power source, DC, pulse, PR pulse or the like can be used, but it is preferable to use pulse, PR pulse or the like. As a result, the diffusion of copper ions is improved to improve the throwing power, the current larger than the direct current is passed to make the deposited copper film dense, and the plating time can be shortened.
[0071]
Here, in the case of a DC power supply, the current density is 0.01 A / dm.²~ 30A / dm²Degree is applicable, 0.1 A / dm²~ 3A / dm²The degree is preferred. In the case of pulse power supply, 0.01 A / dm²~ 200A / dm²The degree is applicable. Thereby, while preventing the fall of productivity, generation | occurrence | production of burnt plating can be prevented. Further, if the temperature of the copper plating solution is too low, the deposition efficiency is deteriorated and the physical properties are deteriorated. If the temperature is too high, the stability (uniformity) of the plating solution is deteriorated and management becomes difficult. About 25 ° C. is applicable, and about 25 ° C. is preferable.
[0072]
Then, after completion of the first stage plating process, the substrate W is transported to the water washing section 20 and washed with water as necessary (step 3), and then the washed water is placed on the second plating treatment section 22b. Transport to one.
[0073]
Next, in the second plating part 22b, the surface of the substrate W has a high copper sulfate concentration and a low sulfuric acid concentration, for example, copper sulfate 100 to 300 g / L, sulfuric acid 10 to 100 g / L. And performing a second-stage plating process using a copper sulfate plating solution (second plating solution) having an excellent leveling property and containing an additive for improving the leveling property to embed copper (step 4). . At this time, since the seed layer 7 (see FIG. 39A and FIG. 40A) is reinforced by performing the first-stage plating process and becomes a complete one without a thin portion, the seed layer 7 Thus, the current flows uniformly, and the void-free copper can be embedded.
[0074]
An additive having an effect of improving the leveling property is, for example, an organic nitrogen compound, specifically, a polyalkylenimine such as a phenatidine compound, a phthalocyanine compound, polyethyleneimine, polybenzylethyleneimine, and a derivative thereof, Thiourea derivatives such as N-dye substitution compounds, phenosafranine, safranine azonaphthol, safranine compounds such as diethyl safranine azophenol, dimethyl safranine dimethylaniline, polyepichlorohydrin and its derivatives, phenylthiazonium compounds such as thioflavine, acrylamide, Examples thereof include nitrogen-containing compounds such as amides such as propylamide and polyacrylic acid amide.
[0075]
Here, the leveling property means the property with respect to the surface flatness, and when plating is performed using a plating solution having excellent leveling property, the film growth at the entrance of the micro-dent is slowed down. While preventing the occurrence, copper can be uniformly filled in the fine recess without any gap, and the surface can be made flatter.
[0076]
The polarization range (copper deposition potential) of the first plating solution is −0.2 V or less, more preferably about −1.5 to −0.2 V, for example, when an Ag—AgCl electrode is used as the electrode. The polarization range (copper deposition range) of the second plating solution is about 0.1 to -0.1 V, for example, when an Ag-AgCl electrode is used as the electrode.
[0077]
The inside of the contact hole, especially the sidewall at the bottom of the contact hole, is generally poor in conductivity because of the thin seed layer (high resistance due to the high deposition potential). Although it is difficult to deposit, the surface of the seed layer with different thickness and different deposition potential (seed layer adheres to the entire surface) can be obtained by using the first plating solution that has high polarization and does not precipitate copper unless the voltage is high. When the barrier layer is exposed, copper plating can be uniformly applied to the barrier layer surface).
[0078]
After the completion of the second stage plating process, the substrate W is transported to the water washing section 20 and washed with water as necessary (step 5). Thereafter, the washed substrate W is transported to the bevel etch / chemical solution cleaning section 16. Then, the bevel etch / chemical solution cleaning unit 16 cleans the substrate W after the copper plating process with the chemical solution, and etches and removes a thin copper thin film formed on the bevel portion of the substrate W (step 6). Next, the substrate is transported to the cleaning / drying processing unit 12 where the substrate W is cleaned and dried (step 7), and then the substrate is loaded and unloaded by the first transport device 24. Return to cassette 10 (step 8).
[0079]
Between step 7 and step 8, a heat treatment process for the substrate W may be inserted. For example, the electrical characteristics of the copper film can be improved by heat treatment at 200 to 500 ° C., preferably about 400 ° C. For example, by providing the bevel etch / chemical solution cleaning unit 16 with the function of the cleaning / drying processing unit 12 shown in FIG. 1, an annealing processing unit (heat treatment unit) can be provided instead of the cleaning / drying processing unit 12. .
[0080]
  Next, referring to FIG.,otherThe plating method will be described. In this example, all four plating treatment parts 22 shown in FIG. 1 are used for copper embedding, and copper embedding by the plating treatment part 22 is performed without reinforcing the thin part of the seed layer as described above. It is what I do.
[0081]
Here, the plating unit 22 has a divalent copper ion, a complexing agent, and a pH adjusting agent as the copper plating solution 45 (see FIG. 3), and further improves the copper embedding property. Therefore, for example, a plating solution to which a thiazole-based additive is added is used. Other conditions are substantially the same as the copper plating solution (first plating solution) used in the first plating unit 22a of the first embodiment.
[0082]
First, the substrate W on which the seed layer 7 (see FIG. 39A) is formed is taken out from the loading / unloading unit 10 one by one by the first transfer device 24, and the first substrate stage 14 and the second substrate stage 18 are removed. Then, it is carried into one plating processing section 22 via (Step 1).
[0083]
Next, a plating process is performed by the plating unit 22 to embed copper (step 2). That is, this copper plating solution has a high polarization like the first plating solution used in the first plating processing unit 22a of the first embodiment, thereby increasing the deposition potential and improving the electrodeposition property. Thus, it is possible to deposit a plating on a thin portion of the seed layer, which was difficult to deposit with a normal copper sulfate plating solution, and to grow this plating to embed copper without voids. Note that the plating conditions and the like at this time are substantially the same as those of the first stage plating process of the first embodiment.
[0084]
Next, after completion of the plating process, the substrate W is transported to the water washing unit 20 and washed with water as necessary (step 3). Thereafter, the washed substrate W is transported to the bevel etch / chemical solution washing unit 16. Then, the bevel etch / chemical solution cleaning unit 16 cleans the substrate W after the copper plating process with a chemical solution, and etches and removes a thin copper film formed thinly on the bevel portion of the substrate W (step 4). It is conveyed to the cleaning / drying processing unit 12. Then, the cleaning / drying processing unit 12 performs cleaning / drying processing of the substrate W (step 5), and then returns the substrate to the cassette of the loading / unloading unit 10 by the first transport device 24 (step 6). .
An annealing process can be inserted between the cleaning / drying process (step 5) and the unloading (step 6) shown in FIG.
[0085]
Next, examples of the present invention will be described. First, a copper plating solution composed of complex bath compositions 1 to 4 shown in Table 1 and a copper plating solution composed of copper sulfate bath compositions 1 and 2 shown in Table 2 were prepared. FIG. 22 shows current / voltage curves of the complex baths 1 to 3 and the copper sulfate bath 1. Thus, it can be seen that the complex baths 1 to 3 have higher polarization than the copper sulfate bath 1.
[0086]
[Table 1]

[0087]
[Table 2]

[0088]
Example 1
The copper plating solution having the complex bath composition 1 is used as the copper plating solution of the first plating treatment part 22a of the first embodiment, and the current density is 0.5 A / dm.²Then, the first plating process (seed layer reinforcement) with a plating time of 25 seconds is performed, and then the copper plating solution of the copper sulfate bath composition 1 is used as the copper plating solution of the second plating treatment part 22b, and the current density is 2 .5A / dm²Second-stage plating treatment (copper embedding) was performed for 2 minutes of plating time.
[0090]
(Example2)
  The copper plating solution having the complex bath composition 3 is used as the copper plating solution for the first plating treatment part 22a of the first embodiment, and the current density is 0.5 A / dm.²Then, the first plating process (seed layer reinforcement) with a plating time of 25 seconds is performed, and then the copper plating solution of the copper sulfate bath composition 1 is used as the copper plating solution of the second plating treatment part 22b, and the current density is 2 .5A / dm²Second-stage plating treatment (copper embedding) was performed for 2 minutes of plating time.
[0092]
(Comparative Example 1)
Using copper plating solution of copper sulfate bath composition 1, current density 2.5A / dm²Then, a plating process (copper embedding) for 2 minutes was performed.
[0093]
(Comparative Example 2)
Using copper plating solution of copper sulfate bath composition 2, current density 2.5A / dm²Then, a plating process (copper embedding) for 2 minutes was performed.
[0094]
  These examples1, 2And comparative examples1, 2The presence or absence of copper defects embedded in the fine depressions was observed by SEM. Here, the presence of electrodeposition failure means a cavity V where copper does not precipitate at the bottom of the groove, as shown in FIG.₁As shown in FIG. 23 (b), the presence of seam voids means that the voids V are elongated in copper.₂As shown in FIG. 23 (c), the presence of granular voids means that there are granular voids V inside the copper.₃The state which has.
[0095]
[Table 3]

  This gives an example1 and 2In this case, it can be seen that it is possible to embed copper without defective electrodeposition or voids.
[0096]
  Next, a copper plating solution composed of the complex bath compositions 1 to 4 shown in Table 4 and a copper plating solution composed of the copper sulfate bath compositions 1 and 2 shown in Table 5 were prepared.1, 2When the plating treatment was performed in the same manner as in Comparative Examples 1 and 2, the same results as described above were obtained.
[0097]
[Table 4]

[0098]
[Table 5]

[0099]
As described above, according to the present invention, by having a complexing agent in the copper plating solution, the polarization as a plating bath is increased, so that the thin portion of the seed layer is reinforced and trenches or holes having a high aspect ratio. It is possible to uniformly embed copper into the depths of the fine recesses, etc., and the deposited plating is dense, and the danger of microvoids can be avoided. Furthermore, since alkali metal and cyan are not included, it is possible to prevent the semiconductor from being deteriorated by electromigration due to the presence of the alkali metal and to meet the demand for avoiding the use of cyan.
[0100]
FIG. 24 is a diagram showing a planar arrangement configuration of another embodiment of the plating apparatus according to the present invention. In this plating apparatus, a load / unload unit 604, two annealing processing units 606 and a cleaning processing unit 608 are arranged so as to surround the first transporting device 600 and the second transporting device 602, and further, the cleaning processing unit 608. In this configuration, the third transfer device 612 is disposed at a position surrounded by four plating processing units 610. Further, a chemical solution supply system 614 for supplying a plating solution to each plating processing unit 610 is provided.
[0101]
  With this plating equipment,21As shown in FIG. 4, when performing the two-stage plating process of reinforcing the seed layer and embedding copper, the first plating solution having the same composition as described above was used for at least one of the four plating processing units 610. The other plating processing unit 610 is used as the plating processing unit for the first stage plating process, and the plating processing unit for the second stage plating process using the second plating solution having the same composition as described above.
[0102]
FIG. 25 shows an example of a process in which, for example, the surface of the semiconductor substrate W is plated to form a wiring made of a copper film, and the surface of the wiring is selectively covered and protected by a protective layer formed by electroless plating. Indicates.
[0103]
As shown in FIG. 25A, the semiconductor substrate W is made of SiO on the conductive layer 101a of the substrate 100 on which the semiconductor element is formed.₂The contact hole 103 and the wiring trench 104 are formed by the lithography / etching technique, the barrier layer 105 made of TaN or the like is formed thereon, and the seed layer 107 is further formed thereon. The seed layer 107 may be formed in advance by sputtering or the like, and a reinforcing seed layer may be formed on the seed layer 107 in order to reinforce it. Then, as shown in FIG. 25B, the surface of the semiconductor substrate W is plated with copper so that the contact holes 103 and the grooves 104 of the semiconductor substrate W are filled with copper, and the copper film 106 is formed on the insulating film 2. Deposit. Thereafter, the copper film 106 on the insulating film 102 is removed by chemical mechanical polishing (CMP), and the surface of the copper film 106 filled in the contact hole 103 and the wiring groove 104 as shown in FIG. And the surface of the insulating film 102 are made substantially flush with each other, and a wiring protective film 108 is formed on the exposed metal surface.
[0104]
FIG. 26 is a schematic configuration diagram of an electroless plating apparatus. As shown in FIG. 26, this electroless plating apparatus includes a holding means 311 for holding a semiconductor substrate W as a member to be plated on its upper surface, and a surface to be plated (upper surface) of the semiconductor substrate W held by the holding means 311. And a shower head 341 for supplying the plating solution to the surface to be plated of the semiconductor substrate W whose peripheral portion is sealed by the dam member 331. The electroless plating apparatus is further installed near the upper periphery of the holding means 311, a cleaning liquid supply means 351 for supplying a cleaning liquid to the surface to be plated of the semiconductor substrate W, and a collection container for recovering the discharged cleaning liquid and the like (plating waste liquid) 361, a plating solution recovery nozzle (not shown) for sucking and recovering the plating solution held on the semiconductor substrate W, and a motor (rotation drive means) M for rotating the holding means 311.
[0105]
A lamp heater 317 is installed above the holding means 311, and the lamp heater 317 and the shower head 341 are integrated. That is, for example, a plurality of ring-shaped lamp heaters 317 having different radii are installed concentrically, and a large number of nozzles 343 of the shower head 341 are opened in a ring shape from the gaps between the lamp heaters 317. The lamp heater 317 may be constituted by a single spiral lamp heater, or may be constituted by lamp heaters having various other structures and arrangements.
[0106]
The holding means 311 is provided with a substrate mounting portion 313 for mounting and holding the semiconductor substrate W on the upper surface thereof. The substrate placement unit 313 is configured to place and fix the semiconductor substrate W, and specifically, a vacuum suction mechanism (not shown) that vacuum-sucks the semiconductor substrate W to the back side thereof is installed. The holding means 311 is driven to rotate by a motor M, and can be moved up and down by an elevator means (not shown). The weir member 331 has a cylindrical shape, and a seal portion 333 that seals the outer peripheral edge of the semiconductor substrate W is provided at a lower portion thereof, and is installed so as not to move up and down from the illustrated position.
[0107]
The shower head 341 has a structure in which a large number of nozzles 343 are provided so that the supplied plating solution is dispersed in a shower shape and supplied to the surface to be plated of the semiconductor substrate W substantially uniformly. The cleaning liquid supply unit 351 has a structure for ejecting the cleaning liquid from the nozzle 353. The plating solution recovery nozzle is configured to be able to move up and down and turn, and its tip is configured to descend to the inside of the weir member 331 on the peripheral edge of the upper surface of the semiconductor substrate W to suck the plating solution on the semiconductor substrate W. Has been.
[0108]
Next, the operation of this electroless plating apparatus will be described. First, the holding means 311 is lowered from the state shown in the figure to provide a gap with a predetermined dimension between the dam member 331 and the semiconductor substrate W is placed and fixed on the substrate platform 313. For example, a φ8 inch wafer is used as the semiconductor substrate W.
[0109]
Next, the holding means 311 is raised and its upper surface is brought into contact with the lower surface of the dam member 331 as shown in the figure, and at the same time, the outer periphery of the semiconductor substrate W is sealed by the seal portion 333 of the dam member 331. At this time, the surface of the semiconductor substrate W is in an open state.
[0110]
Next, the semiconductor substrate W itself is directly heated by the lamp heater 317, for example, the temperature of the semiconductor substrate W is set to 70 ° C. (maintained until the end of plating), and then the plating solution heated from the shower head 341 to, for example, 50 ° C. And the plating solution is poured over substantially the entire surface of the semiconductor substrate W. Since the surface of the semiconductor substrate W is surrounded by the dam member 331, all of the injected plating solution is held on the surface of the semiconductor substrate W. The amount of the plating solution to be supplied may be as small as 1 mm (about 30 ml) on the surface of the semiconductor substrate W. The depth of the plating solution retained on the surface to be plated may be 10 mm or less, and may be 1 mm. If a small amount of plating solution is supplied in this way, the heating device for heating the plating solution can be small. In this example, since the temperature of the semiconductor substrate W is heated to 70 ° C. and the temperature of the plating solution is heated to 50 ° C., the surface to be plated of the semiconductor substrate W becomes, for example, 60 ° C., which is the optimum temperature for the plating reaction. Can be. If the semiconductor substrate W itself is heated in this way, the temperature of the plating solution that requires a large amount of power consumption for heating does not have to be raised so high. Therefore, it is possible to prevent the material from changing. The power consumption for heating the semiconductor substrate W itself may be small, and since the amount of the plating solution stored on the semiconductor substrate W is small, the heat of the semiconductor substrate W by the lamp heater 317 can be easily maintained. The capacity is small and the apparatus can be made compact. If means for directly cooling the semiconductor substrate W itself is also used, it is possible to change the plating conditions by switching between heating and cooling during plating. Since the plating solution held on the semiconductor substrate is small, temperature control can be performed with high sensitivity.
[0111]
Then, the semiconductor substrate W is instantaneously rotated by the motor M to uniformly wet the surface to be plated, and then the surface to be plated is plated while the semiconductor substrate W is stationary. Specifically, the semiconductor substrate W is rotated at 100 rpm or less for 1 second so that the surface to be plated of the semiconductor substrate W is uniformly wetted with a plating solution, and then is kept stationary to perform electroless plating for 1 minute. The instantaneous rotation time is at most 10 sec.
[0112]
After the plating process is completed, the tip of the plating solution recovery nozzle 365 is lowered to the vicinity of the inside of the weir member 331 at the peripheral edge of the surface of the semiconductor substrate W, and the plating solution is sucked. At this time, if the semiconductor substrate W is rotated at a rotation speed of, for example, 100 rpm or less, the plating solution remaining on the semiconductor substrate W can be collected in the portion of the dam member 331 on the peripheral edge of the semiconductor substrate W by the centrifugal force. The plating solution can be recovered with good and high recovery rate. Then, the holding means 311 is lowered to separate the semiconductor substrate W from the weir member 331, and the rotation of the semiconductor substrate W is started, and the cleaning liquid (ultra pure water) is applied to the surface of the semiconductor substrate W to be plated from the nozzle 353 of the cleaning liquid supply means 351. By spraying and cooling the surface to be plated, the electroless plating reaction is stopped by diluting and washing. At this time, the cleaning liquid sprayed from the nozzle 353 may also be applied to the weir member 331 to simultaneously clean the weir member 331. The plating waste liquid at this time is collected in the collection container 361 and discarded.
[0113]
In addition, the plating solution that has been used once is not reused but disposable. As described above, since the amount of the plating solution used in this apparatus can be very small as compared with the conventional case, the amount of the plating solution to be discarded is small even without being reused. In some cases, the plating solution recovery nozzle may not be installed, and the used plating solution may be recovered in the recovery container 361 as a plating waste solution together with the cleaning solution.
Then, after the semiconductor substrate W is rotated at high speed by the motor M and spin-dried, it is taken out from the holding means 311.
[0114]
FIG. 27 is an overall layout diagram showing a plating apparatus according to another embodiment of the present invention, in which a polishing processing unit is incorporated so that the substrate surface can be polished immediately after plating. This plating apparatus includes substrate cassettes 531 and 531 for loading and unloading, a plating processing unit 512, cleaning processing units 535 and 535 for cleaning a substrate, two transfer devices 514a and 514b, a reversing machine 539, 539, polishing processing units 541 and 541, and a spin dryer 534.
[0115]
The flow of the substrate W is, for example, as follows. First, the transfer device 514a takes out the substrate W before processing from any of the substrate cassettes 531 for loading, and after the plating processing unit 512 performs the plating process, the transfer device 514a delivers the substrate W to any of the reversing machines 539. After the surface to be processed is faced down, it is delivered to the other transport device 514b. The transfer device 514b delivers the substrate W to one of the polishing processing units 541 and performs predetermined polishing. The polished substrate W is taken out by the transfer device 514b, cleaned by one of the cleaning processing units 535, transferred to the other polishing processing unit 541 and polished again, and then cleaned by the transfer device 514b. It is transported to the processing unit 535 and cleaned. After cleaning, the substrate W is transported to the other reversing machine 539 by the transporting device 514b and the surface to be processed is inverted upward, and then transported to the spin dryer 534 by the transporting device 514a and spin-dried, and then transported again. The unloaded substrate cassette 531 is accommodated by the device 514a.
[0116]
  FIG. 28 shows an example of this type of polishing processing unit 541. As shown in FIG.TheThe pulling ring 10-2 adsorbs the semiconductor substrate W and polishes the polishing surface 10-1a of the polishing table 10-1 by contacting and pressing the surface on which the copper film 6 (see FIG. 39B) of the semiconductor substrate W is formed. . In this polishing, the copper film 6 is basically polished. The polishing surface 10-1a of the polishing table 10-1 is made of foamed polyurethane such as IC1000, or one in which abrasive grains are fixed or impregnated. The copper film 6 is polished by the relative movement of the polishing surface 10-1a and the semiconductor substrate W.
[0117]
Silica, alumina, ceria, or the like is used for the abrasive grains for polishing the copper film 6 or the slurry ejected from the slurry nozzle 10-6, and the oxidizing agent is mainly acidic, such as hydrogen peroxide. A material that oxidizes Cu is used. In order to keep the temperature at a predetermined value in the polishing table 10-1, a temperature adjusting fluid pipe 542 for passing a liquid adjusted to a predetermined temperature is connected. In order to keep the temperature of the slurry at a predetermined value, the slurry nozzle 10-6 is provided with a temperature regulator 10-7. Moreover, although illustration is abbreviate | omitted, the water etc. at the time of dressing are temperature-controlled. Thus, the chemical reaction rate is kept constant by maintaining the temperature of the polishing table 10-1, the temperature of the slurry, the temperature of water at the time of dressing, etc. at predetermined values. In particular, ceramic such as alumina or SiC having good thermal conductivity is used for the polishing table 10-1.
[0118]
For detection of the end point of polishing, an eddy current film thickness measuring device 10-8 or an optical film thickness measuring device 10-9 provided on the polishing table 10-1 is used to measure the film thickness of the copper film 6, Alternatively, when the surface of the barrier film 5 (see FIG. 39A) is detected and the film thickness of the copper film 6 is 0 or the surface of the barrier film 5 is detected, the end point of polishing (primary polishing) is set.
[0119]
FIG. 29 is a diagram showing a configuration of a cleaning mechanism for cleaning the polishing surface 10-1a of the polishing table 10-1. As shown in the drawing, a plurality (four in the figure) of mixed injection nozzles 10-11a to 10-11d for mixing and injecting pure water and nitrogen gas are arranged above the polishing table 10-1. Nitrogen gas pressure-adjusted by the regulator 216 from the nitrogen gas supply source 214 is supplied to the mixing injection nozzles 10-11a to 10-11d through the air operator valve 218, and pressure is supplied from the pure water supply source 215 by the regulator 217. The pure water adjusted is supplied through the air operator valve 219.
[0120]
The mixed gas and liquid are changed by changing the parameters of the liquid and / or gas pressure, temperature, nozzle shape and the like by the injection nozzle, respectively. 2) Solidification of fine particles by solidification of liquid, and (3) liquid evaporation and gasification (these (1), (2), and (3) are called atomization or atomization here) A mixture of gas components is jetted with a predetermined direction toward the polishing surface of the polishing table 10-1.
[0121]
When the polishing surface 10-1a is regenerated (dressing) by the relative movement of the polishing surface 10-1a and the dresser 10-10, a mixed fluid of pure water and nitrogen gas is mixed from the mixed injection nozzles 10-11a to 11-11d. 10-1a is sprayed and washed. The pressure of nitrogen gas and the pressure of pure water can be set independently. In this example, manual drive regulators are used for both the pure water line and the nitrogen line, but regulators that can change the set pressure based on an external signal may be used. As a result of cleaning the polishing surface 10-1a using the cleaning mechanism, the slurry remaining on the polishing surface in the polishing process could be removed by cleaning for 5 to 20 seconds.
[0122]
FIG. 30 is a perspective view showing the transfer device 514a (514b). FIG. 31 is a view showing a robot hand 540 attached to the transfer device 514a (514b), FIG. 31 (a) is a plan view, and FIG. 31 (b) is a side sectional view.
[0123]
The transfer device 514a (514b) is configured by attaching robot hands 540 and 540 to the tips of two arms 542 and 542 attached to the upper part of the robot main body 543, respectively. Both robot hands 540 and 540 are arranged so as to overlap each other with a predetermined gap therebetween. The arm 542 expands and contracts, so that the substrate W placed on the robot hand 540 can be conveyed in the front-rear direction. Further, the robot body 543 rotates and / or moves, so that the substrate W can be transferred in an arbitrary direction.
[0124]
As shown in FIG. 31, four film thickness sensors S are directly embedded and attached to the robot hand 540. Any film thickness sensor S can be used as long as it can measure the film thickness, but an eddy current sensor is preferably used. The eddy current sensor measures the film thickness by generating eddy current and detecting the frequency and loss of the current returned through the substrate W, and is used in a non-contact manner. Further, an optical sensor is also suitable as the film thickness sensor S. The optical sensor can irradiate the sample with light and measure the film thickness directly from the information of the reflected light. It can measure the film thickness of not only metal films but also oxide films. It is. The installation position of the film thickness sensor S is not limited to that shown in the figure, and an arbitrary number is attached to a place to be measured. The robot hand 540 includes a dry hand that handles a dry substrate W and a wet hand that handles a wet substrate W, and the film thickness sensor S can be attached to either of them. However, when this transfer device 514a (514b) is used in the plating processing unit 512, it is necessary to first measure the film thickness of the substrate W with only the seed layer attached. First, it is necessary to measure the thickness of the substrate W in a dry state where the substrate is placed. Therefore, it is desirable to attach the film thickness sensor S to the dry hand.
[0125]
A signal detected by the film thickness sensor S is sent to an arithmetic device, and a calculation such as taking a difference between the film thickness of the substrate W before processing and the film thickness of the substrate W after processing is performed, and the film thickness is set to a predetermined value. Output to a display. Any calculation method may be used as long as the film thickness can be measured appropriately.
[0126]
According to this example, since the film thickness can be measured while the robot hand 540 is transporting the substrate W, it is not necessary to separately provide a film thickness measurement step during the substrate processing step, and throughput can be reduced. There is no effect. Further, since the film thickness sensor S is attached to the robot hand 540, space saving can be realized.
[0127]
32A and 32B are diagrams showing another example of the transfer device 514a (514b), in which FIG. 32A is a schematic plan view, and FIG. 32B is a schematic side view. As shown in FIG. 32, in this example, five film thickness sensors S are attached to the lower part of the robot hand 540 of the robot body 543. That is, a disk-shaped mounting plate 545 having a size substantially the same as that of the substrate W is installed below the robot hand 540, and five film thickness sensors S are mounted on the mounting plate 545. The attachment plate 545 is fixed to the robot body 543, but may be fixed to another member.
[0128]
Each film thickness sensor S can be measured in a wide area of the entire substrate W by being attached at a position that does not overlap the robot hand 540 as shown. This example also saves space and enables measurement in a very short time. Then, by stopping the substrate W on the mounting plate 545, it becomes possible to measure the film thickness at the fixed point of the substrate W. On the other hand, the substrate W on the robot hand 540 passes through the mounting plate 545 without stopping. By doing so, it is possible to measure while scanning. Further, since the film thickness sensor S is integrated with the robot body 543, stable detection can be performed. Further, when the mounting plate 545 is fixed to another member instead of the robot body 543, the distance between the substrate W and the sensor can be adjusted by arbitrarily changing the height of the robot hand.
[0129]
The point where the detected signal is sent to the arithmetic unit and the film thickness is measured is the same as the example shown in FIG. However, in the case of measurement while scanning, since the measurement point changes with time, it is preferable to calculate the film thickness by calculating by the moving average method.
[0130]
FIG. 33 is a diagram showing another example of film thickness measurement, FIG. 33 (a) is a schematic plan view, and FIG. 33 (b) is a schematic side view. In the example shown in FIG. 33, three film thickness sensors S are installed above the entrance / exit part 550 of the substrate W of the plating processing part 512 shown in FIG. That is, a rectangular mounting plate 551 is installed at the upper part of the entrance / exit portion 550, and three film thickness sensors S are mounted in series on the lower surface of the mounting plate 551. The mounting plate 551 may be fixed to the plating processing unit 512, may be fixed to the robot main body 543 of the transfer device 514a (514b), or may be fixed to other members.
[0131]
According to this configuration, the film thickness sensor S scans the substrate W both when the substrate W is put into the plating processing unit 512 and when it is taken out, and thus it is suitable for scan measurement. Further, by installing several rows of film thickness sensors S as in this example, an arbitrary point on the substrate W can be scanned. Further, the distance between the substrate W and the sensor can be adjusted by arbitrarily changing the height of the robot hand.
The signal detected by the film thickness sensor S is calculated by a calculation device, but in the case of scan measurement, calculation processing by the moving average method is suitable.
[0132]
In addition, the film thickness sensor S may be installed in the vicinity of the entrance / exit where the substrate W of the polishing processing unit 541 shown in FIG. Note that when the substrate W is loaded into the polishing processing unit 541, the surface to be processed of the substrate W faces downward, and therefore it is preferable to install the film thickness sensor S on the lower side of the polishing processing unit 541 where the substrate W is loaded. (Of course, even if the film thickness sensor S is installed on the upper side, the film thickness can be measured, but the lower side is more accurate). After the polishing is completed, the surface to be processed of the substrate W is in a wet state, but if a film thickness sensor that can be measured in a wet state is used, the film thickness is measured by the same method as in the case of the plating unit 512. it can.
[0133]
34 is a schematic front view of the vicinity of the reversing machine 539, and FIG. 35 is a plan view of the reversing arms 553 and 553. As shown in FIGS. 34 and 35, the reversing arms 553 and 553 have a function of sandwiching and holding the outer periphery of the substrate W from both the left and right sides, and reversing it by rotating it 180 degrees. A circular mounting base 555 is installed immediately below the reversing arms 553 and 553, and a plurality of film thickness sensors S are installed on the mounting base 555. The mounting base 555 is configured to be movable up and down by a drive mechanism 557.
[0134]
When the substrate W is reversed, the mounting base 555 stands by at the position indicated by the solid line below the substrate W, and before or after the reversal, the mounting base 555 is moved up to the position indicated by the dotted line to move the film thickness sensor S to the reverse arm 553. , 553 are brought close to the substrate W and the film thickness is measured.
[0135]
According to this example, since there is no restriction such as the arm 542 of the transfer robot 514, the film thickness sensor S can be installed at an arbitrary position on the mounting base 555. Further, since the mounting base 555 is configured to be movable up and down, it is possible to adjust the distance between the substrate W and the sensor at the time of measurement. It is also possible to attach a plurality of types of sensors according to the detection purpose and change the distance between the substrate W and each sensor for each measurement of the sensor. However, since the mounting base 555 moves up and down, it takes a little measurement time.
[0136]
FIG. 36 shows an overall layout of a plating apparatus according to still another embodiment of the present invention. This plating apparatus includes a load / unload unit 915, a pair of annealing treatment units 986, a bevel etch / chemical solution cleaning unit 984, a substrate stage 978, a water washing unit 982 having a function of inverting the substrate by 180 °, and a first illustrated in FIG. There is one first plating unit 980 that performs one-stage plating (seed layer reinforcement) and three second plating units 972 that perform second-stage plating (copper embedding) shown in FIG. is doing. Further, a first transport device 917 that can move between the loading / unloading unit 915, the annealing processing unit 986, the bevel etch / chemical solution cleaning unit 984, and the substrate stage 978, a substrate stage 978, and a water washing unit 982. In addition, a second transport device 924 is provided that can move the substrate between the first plating processing unit 980 and the second plating processing unit 972.
[0137]
In this example, first, the substrates W having the seed layer 7 (see FIG. 39A) formed on the surface are taken out one by one from the load / unload unit 915 by the first transfer device 917 and passed through the substrate stage 978. It is carried into the first plating processing unit 980.
[0138]
Next, in the first plating processing unit 980, the surface of the substrate is subjected to a first step plating process using a first plating solution to reinforce the thin portion of the seed layer 7 and complete it. . As described above, the first plating solution is based on, for example, copper pyrophosphate, and has a polarization higher than that of a normal copper sulfate plating solution by adding a complexing agent such as pyrophosphate to the base. is there.
Then, after completion of the first stage plating process, the substrate W is transported to the water washing unit 982 and washed as necessary, and then the washed substrate W is transported to one of the second plating processing units 972. .
[0139]
Next, in the second plating processing unit 972, the surface of the substrate W is subjected to a second stage plating process using a second plating solution to embed copper. At this time, since the seed layer 7 (see FIG. 39A and FIG. 40A) is reinforced by performing the first-stage plating process and becomes a complete one without a thin portion, the seed layer 7 Thus, the current flows uniformly, and the void-free copper can be embedded. As described above, the second plating solution has a composition having an excellent leveling property such as a low concentration of sulfuric acid.
[0140]
After completion of the second stage plating process, the substrate W is transported to the water washing unit 982 and washed with water as necessary, and then the washed substrate W is transported to the bevel etch / chemical solution washing unit 984. The bevel etch / chemical solution cleaning unit 984 cleans the copper-plated substrate W with a chemical solution, etches away the thin copper film formed on the bevel portion of the substrate W, and rinses with pure water. Then spin at high speed and spin dry. Thereafter, the substrate after spin drying is transferred to the annealing unit 986 and annealed. After the annealing is completed, the substrate is returned to the cassette of the load / unload unit 915 by the first transfer device 917.
[0141]
FIG. 37 is an overall layout diagram of a plating apparatus according to still another embodiment of the present invention. This plating apparatus includes a loading / unloading unit 800 and a processing unit 802. In consideration of the throughput of the semiconductor wafer, a single transporting device 804 is provided at the center of the processing unit 802, and the periphery of the transporting device 804. A plurality of plating processing units 806 and cleaning / drying processing units (spin-rinse-dry units) 808 are respectively arranged. In this example, three plating processing units 806 and three cleaning / drying processing units 808 are arranged around one transport device 804. Instead of the cleaning / drying processing unit 806, a bevel etch / chemical solution cleaning unit may be arranged. The plating processing unit 808 may be a so-called face-up type or a so-called face-down type.
[0142]
FIG. 38 is an overall layout diagram of a plating apparatus according to still another embodiment of the present invention. This plating apparatus has two cassette table annealing units 830 on which a substrate cassette 822 containing a substrate W such as a semiconductor wafer is mounted, which is located in a load station 820. In addition, a pair of cleaning and drying units 834, a pair of first plating units 836 that perform the above-described first-stage plating process, and two pairs that perform the above-described second-stage plating process are located in the main frame 832. 2nd plating processing part 838.
[0143]
A first transfer device 840 that is located in the load station 820 and delivers substrates between the substrate cassette 822, the annealing unit 830, and the cleaning / drying unit 834 is located in the main frame 832. A second transfer device 842 that transfers substrates between the cleaning / drying unit 834, the first plating unit 836, and the second plating unit 838 is provided.
[0144]
FIG. 41 is an overall layout diagram of a plating apparatus according to still another embodiment of the present invention. The plating apparatus includes a load / unload unit 900, an annealing unit 903, two bevel etch / chemical solution cleaning units 902, a substrate stage 906, and three plating units 901. Further, a first transport device 904 that can freely move the substrate between the loading / unloading unit 900 and the substrate stage 906, a substrate stage 906, an annealing unit 903, a bevel etch / chemical solution cleaning unit 902, and a plating process. A travelable second transfer device 905 is provided for transferring the substrate to and from the unit 901.
[0145]
FIG. 42 is an overall layout diagram of a plating apparatus according to still another embodiment of the present invention. This plating apparatus includes a load / unload unit 1000, a bevel etch / chemical solution cleaning unit 1050, a cleaning / drying processing unit (spin-rinse-dry unit) 1040, and a first stage plating process (seed layer reinforcement) shown in FIG. One first plating processing unit 1010 to be performed, two second plating processing units 1020 to perform second-stage plating processing (copper embedding) shown in FIG. 19, and first plating processing and second plating processing And a cleaning unit 1030 for cleaning the substrate. Further, a first transfer device 1060 for transferring substrates between the load / unload unit 1000, the bevel etch / chemical solution cleaning unit 1050, and the cleaning / drying processing unit 1040, a bevel etch / chemical solution cleaning unit 1050, and cleaning / drying. A travelable second transfer device 1070 is provided that transfers the substrate among the processing unit 1040, the first plating processing unit 1010, the second plating processing unit 1020, and the cleaning unit 1030.
[0146]
Note that the plating processing unit 901 shown in FIG. 41 and the plating processing units 1010 and 1020 shown in FIG. 42 are appropriately converted into a first plating processing unit and a second plating processing unit that perform a first-stage plating process using the first plating solution. Of course, it may be used as a second plating treatment section for performing the second-stage plating treatment using the plating solution.
[0147]
【The invention's effect】
As described above, according to the present invention, by having a complexing agent in the copper plating solution, the polarization as a plating bath is increased, so that the thin portion of the seed layer is reinforced and trenches or holes having a high aspect ratio. It is possible to uniformly embed copper into the depths of the fine recesses, etc., and the deposited plating is dense, and the danger of microvoids can be avoided. Furthermore, since alkali metal and cyan are not included, it is possible to prevent the semiconductor from being deteriorated by electromigration due to the presence of the alkali metal and to meet the demand for avoiding the use of cyan.
[Brief description of the drawings]
FIG. 1 is a plan layout view of a plating apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a gas flow in the plating apparatus shown in FIG.
FIG. 3 is a cross-sectional view showing the entirety of a plating process portion used in FIG. 1 during a plating process.
FIG. 4 is a plating solution flow chart showing a state of a plating solution flow in a plating processing section.
FIG. 5 is a cross-sectional view showing the entirety of the plating processing section when not plating (at the time of substrate delivery).
FIG. 6 is a cross-sectional view showing the entirety of the plating processing section during maintenance.
FIG. 7 is a cross-sectional view for explaining the relationship among the housing, the pressing ring, and the substrate when the substrate is delivered by the plating unit.
FIG. 8 is a partially enlarged view of FIG. 7;
FIG. 9 is a diagram for explaining the flow of a plating solution during plating processing and during non-plating in a plating processing section.
FIG. 10 is an enlarged cross-sectional view of a centering mechanism of a plating processing unit.
FIG. 11 is a cross-sectional view showing a power supply contact (probe) of the plating processing section.
FIG. 12 is a diagram illustrating a schematic configuration example of a cleaning / drying processing unit.
FIG. 13 is a diagram illustrating a schematic configuration example of a bevel etch / chemical solution cleaning unit;
FIG. 14 is a side view showing a rotation holding device used in a cleaning / drying processing unit and a bevel etch / chemical solution cleaning unit.
15 is a plan view of FIG. 14. FIG.
16 is a partial sectional view showing details of a holding member for supporting a disk-like member in the rotary holding device shown in FIG. 14;
FIG. 17 is a view taken along the line AA in FIG. 16;
FIGS. 18A and 18B are diagrams illustrating a transfer device, in which FIG. 18A is an external view, FIG. 18B is a plan view of the robot hand, and FIG. 18C is a cross-sectional view of the robot hand.
FIG. 19 is a diagram showing a flow of processing in the plating method according to the embodiment of the present invention.
FIG. 20 is a graph showing the relationship between voltage and current density in two differently polarized copper plating solutions.
FIG. 21otherIt is a figure which shows the flow of the process in the plating method.
22 is a graph showing current / voltage curves of complex baths 1 to 3 and copper sulfate bath 1 in Examples. FIG.
FIG. 23 is a diagram schematically showing electrodeposition defects, seam voids, and granular voids in SEM observation.
FIG. 24 is a plan layout view showing another example of the plating apparatus of the present invention.
FIG. 25 is a schematic view showing another example of a plating process.
FIG. 26 is a schematic configuration diagram of an electroless plating treatment unit.
FIG. 27 is a plan layout view of a plating apparatus incorporating a polishing processing unit.
FIG. 28 is a diagram illustrating a schematic configuration example of a polishing processing unit.
FIG. 29 is a diagram showing a schematic configuration of a polishing table cleaning machine.
FIG. 30 is a perspective view showing a transfer device.
FIGS. 31A and 31B are diagrams showing a robot hand attached to the transfer device, where FIG. 31A is a plan view and FIG. 31B is a side sectional view;
FIGS. 32A and 32B are diagrams showing another example of the transport device, where FIG. 32A is a schematic plan view, and FIG. 32B is a schematic side view.
33A and 33B are diagrams showing still another example of film thickness measurement, in which FIG. 33A is a schematic plan view, and FIG. 33B is a schematic side view.
FIG. 34 is a schematic front view of the vicinity of a reversing machine.
FIG. 35 is a plan view of a reversing arm portion.
FIG. 36 is a plan layout view showing still another example of the plating apparatus of the present invention.
FIG. 37 is a plan layout view showing still another example of the plating apparatus of the present invention.
FIG. 38 is a plan layout view showing still another example of the plating apparatus of the present invention.
FIG. 39 is a diagram showing an example of forming a copper wiring by a copper plating treatment in the order of steps.
FIG. 40 is a diagram schematically showing the state of a seed layer in a conventional example and voids generated in association therewith.
FIG. 41 is a plan layout view showing still another example of the plating apparatus of the present invention.
FIG. 42 is a plan layout view showing still another example of the plating apparatus of the present invention.
[Explanation of symbols]
5 Barrier layer
6 Copper film
7 Seed layer
10 Load / Unload Club
12 Cleaning / drying processing section
14 First substrate stage
16 Bevel Etch / Chemical Cleaning Unit
18 Second substrate stage
20 Flushing club
22 Plating part
22a First plating section
22b Second plating processing section
24, 26, 28 transport device
45 Plating solution
46 Plating tank
47 Head
48 Anode
49 Plating room
50 Plating tank
53 Plating solution ejection nozzle
55 Plating solution supply pipe
57, 59, 120 Plating solution outlet
58 Weir member
62 Vertical straightening ring
63 Horizontal rectifying ring
70 housing
72 Substrate holder
75 Air vent hole
76 Cathode contact
77 Feeding contact
240 Press ring
242 Press rod
244 Sealing material
270 Centering mechanism
272 Bracket
274 blocks
276 Axis

Claims (6)

In a plating method for plating a substrate having a fine depression covered with a seed layer and filling the fine depression with a metal,
The first substrate is made of a substance containing a divalent copper ion and a complexing agent having a concentration of 1 to 10 g / L and containing no alkali metal and cyan, and has a polarization higher than that of the second plating solution described below. The first stage plating process for reinforcing the seed layer is performed by immersing in the plating solution of
A plating method comprising performing a second-stage plating process in which the substrate is immersed in a second plating solution and copper is embedded in the fine recesses.   The complexing agent is ethylenediaminetetraacetic acid, ethylenediamine, N, N ′, N ″, N ′ ″ ethylenedinitrotetrapropan-2-ol, pyrophosphoric acid, iminodiacetic acid, diethylenetriaminepentaacetic acid, diethylenetriamine, triethylenetetramine, 2. Tetraethylenepentamine, diaminobutane, hydroxyethylethylenediamine, ethylenediaminetetrapropionic acid, ethylenediaminetetramethylenephosphonic acid, diethylenetriaminetetramethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid or a derivative thereof Plating method. Wherein the first plating solution, as a pH adjusting agent, co Li comma other plating method according to claim 1, wherein further comprising a hydroxide tetramethylammonium beam.   The plating method according to claim 1, wherein the concentration of the complexing agent in the first plating solution is 20 to 200 g / L. A substrate having a fine depression covered with a seed layer is made of a substance containing a divalent copper ion and a complexing agent having a concentration of 1 to 10 g / L and containing no alkali metal and cyanide. A first plating treatment unit that performs a first-stage plating treatment that reinforces the seed layer by immersing in a first plating solution that is more polarized than the plating solution of
First plating solution supply means for supplying a first plating solution to the plating tank of the first plating processing unit;
A second plating treatment section for immersing the substrate in which the seed layer is reinforced by the first-stage plating treatment in a second plating solution, and performing a second-stage plating treatment for embedding copper inside the fine depression; ,
A second plating solution supply means for supplying a second plating solution to the plating tank of the second plating processing unit;
A plating apparatus comprising transport means for transporting the substrate from the first plating processing section to the second plating processing section.   The plating apparatus according to claim 5, wherein the concentration of the complexing agent in the first plating solution is 20 to 200 g / L.

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