JP3866012B2

JP3866012B2 - Electroless plating method and apparatus

Info

Publication number: JP3866012B2
Application number: JP2000165801A
Authority: JP
Inventors: 裕章井上; 憲二中村; 守治松本; 浩二三島; 哲朗松田; 尚史金子
Original assignee: Ebara Corp; Toshiba Corp
Current assignee: Ebara Corp; Toshiba Corp
Priority date: 2000-06-02
Filing date: 2000-06-02
Publication date: 2007-01-10
Anticipated expiration: 2020-06-02
Also published as: JP2001342573A

Description

【０００１】
【発明の属する技術分野】
本発明は、半導体基板の配線形成（シード層形成や、シード層の上にこれを補強する目的で形成される補助シード層形成も含む）や配線保護膜形成などに用いて好適な無電解めっき方法及び装置に関するものである。
【０００２】
【従来の技術】
従来、半導体基板上に配線回路を形成する材料としてアルミニウム又はアルミニウム合金が一般に用いられてきたが、集積度の向上に伴い、より伝導率の高い材料を配線材料に採用することが要求されている。このため配線材料として銅又はその合金を用い、これを半導体基板にめっき処理することで基板に形成された配線パターン用の溝に充填する方法が提案されている。
【０００３】
配線パターン用の溝に銅又はその合金を充填する方法としては、ＣＶＤ（化学的蒸着）やスパッタリング等各種の方法が知られているが、金属層の材質が銅又はその合金である場合、即ち、銅配線を形成する場合には、ＣＶＤではコストが高く、またスパッタリングでは高アスペクト（パターンの深さの幅に対する比が大きい）の場合に埋め込みが不可能である等の短所を有しており、めっきによる方法が最も有効だからである。
【０００４】
一方無電解めっき装置の中には、従来めっき工程やめっきに付帯する前処理工程や洗浄工程を行うユニットを複数設けて無電解めっき処理を行う無電解めっき装置の代わりに、これらの各処理工程を一つのユニットで行う無電解めっき装置が提案されている。図５はこの種の無電解めっき装置の概略構成を示す図である。同図に示すようにこの無電解めっき装置は、モータＭによって回転駆動される保持手段８１上に載置・固定された半導体基板Ｗの周囲にカバー８３を設置し、半導体基板Ｗを点線で示す位置でモータＭによって回転しながらめっき液をめっき槽８７からポンプＰによって半導体基板Ｗの上部中央に供給し、回転による遠心力でめっき液を半導体基板Ｗの上面全体に広げてめっきを行いながら、半導体基板Ｗから落ちためっき液をカバー８３のめっき液回収部８５からめっき槽８７に戻して循環させる。
【０００５】
一方めっき終了後の半導体基板Ｗは同図に実線で示す位置まで下降して回転し、図示しない洗浄水供給手段から洗浄水を供給することでその表面からめっき液を洗い流して洗浄液回収部８６に集めて排水する。
【０００６】
しかしながら上記従来の無電解めっき装置においても以下のような各種問題点があった。
▲１▼半導体基板の被めっき面に常時めっき液を滴下しているのでめっき液を大量に循環使用することとなってしまう。また大量のめっき液を循環使用すると、大型ポンプが必要になり、ポンプの発熱による液温上昇に対する液温維持装置が必要で装置コストが上昇するばかりか装置が大型化し、ひいてはこの装置を収納するクリーンルームコストが上昇してしまう。
【０００７】
▲２▼めっき液を常時循環使用するので無電解めっきの原理上、副生成物が系内に蓄積し、安定なめっきプロセスが維持できない。また安定なめっきプロセスを得るためには、めっき液の分析及び液調整装置が必要となり、装置コストの上昇及びクリーンルームコストの上昇を招く。
【０００８】
▲３▼めっき液を大量に循環使用するため各装置構成部材からパーティクルが発生し易く循環経路内に濾過装置Ｆを設置する必要が生じ、装置コスト上昇及びクリーンルームコスト上昇を招く。
【０００９】
▲４▼被めっき面上の一箇所のみに常時めっき液を供給しながらめっきを行うと、めっき液を滴下していた部分のめっき膜厚が他の部分のめっき膜厚に比べて薄くなることが実験で確かめられており、膜厚の面内均一性が悪化する。これはめっき液を滴下した部分のみが他の部分に比べてめっき液の流速や厚み等が異なることでその反応状態が異なることが原因と考えられる。
【００１０】
▲５▼無電解めっきを行わせるためには、被めっき面とめっき液との反応面の温度を所定の一定温度に維持しておく必要があるので、大量のめっき液をめっき反応に最適な温度まで常時昇温させておく手だてが必要となり、装置コストの上昇及びクリーンルームコストの上昇を招き、且つめっき液を常時昇温させておくのでめっき液の劣化を促進してしまう。
【００１１】
▲６▼常時半導体基板を回転させているので、半導体基板の周速による放熱で温度降下が顕著になり安定なめっきプロセスが得られない。
【００１２】
▲７▼めっき液を滴下ではなく噴霧によって被めっき面に供給しようとした場合は、めっき液の温度制御が不確実になり安定なめっきプロセスが得られない。
【００１３】
【発明が解決しようとする課題】
本発明は上述の点に鑑みてなされたものでありその目的は、めっき液の使用量を少なくでき、安定なめっきプロセスが維持でき、装置の小型化と低コスト化が図れ、膜厚の面内均一性が図れ、さらに昇温によるめっき液の劣化を防止できる無電解めっき方法及び装置を提供することにある。
【００１４】
【課題を解決するための手段】
上記問題点を解決するため請求項１に記載の発明は、基板の被めっき面を上向きにし、この被めっき面上にこの被めっき面を開放した状態で囲む堰部材を当接し、前記堰部材で囲まれた前記基板の被めっき面上に無電解めっき処理液を供給する工程と、前記無電解めっき処理液を前記基板の被めっき面上に所定時間溜めて保持して無電解めっき処理を行う工程とを、連続して行うことを特徴とする。これによって少量の無電解めっき処理液で被めっき面の処理が行え、無電解めっき処理液供給用のポンプとして小型のものが使用でき、無電解めっき装置のコンパクト化が図れ、これを収納するクリーンルームコストの低減化も図れる。また使用する無電解めっき処理液が少量なので無電解めっき処理液の昇温・保温が容易で即座に行える。
請求項２に記載の発明は、前記基板の被めっき面上に保持する無電解めっき処理液の深さが１０ｍｍ以下であることを特徴とする。
【００１５】
請求項３に記載の発明は、前記無電解めっき処理液を供給する工程と、前記無電解めっき処理液を前記基板の被めっき面上に所定時間溜めて保持して無電解めっき処理を行なう工程との間に、前記基板の被めっき面上に供給した無電解めっき処理液を被めっき面全体に接液させる工程を設けたことを特徴とする。基板の被めっき面上の一部に供給した無電解めっき処理液を被めっき面全体に接液させる工程としては、基板を動かすこと〔即ち例えば無電解めっき処理液が供給された基板を回転させることや、振動させることや、揺動（揺り動かす）こと等〕や、供給した無電解めっき処理液を動かすこと〔掻き均し部材を用いて掻き均すことや、液面に送風すること等〕である。
請求項４に記載の発明は、前記無電解めっき処理液を被めっき面全体に接液させる工程は、基板を１０秒以下の時間回転させる工程であることを特徴とする。
【００１６】
請求項５に記載の発明は、前記無電解めっき処理液を前記基板の被めっき面上に所定時間溜めて保持して無電解めっき処理を行なう工程は、基板とめっき液を静止した状態で行なうことを特徴とする。このように構成すれば基板を回転しながら処理を行う場合に比べて基板の周速による放熱が生じず、各部の反応温度の均一化が図れ、安定なプロセスが得られる。
【００１７】
請求項６に記載の発明は、前記基板の被めっき面上に無電解めっき処理液を接液させる前まで被めっき面に不活性ガスを吹き付けることを特徴とする。
【００１９】
請求項７に記載の発明は、被めっき面を上向きにして基板を保持する保持手段と、前記保持手段に保持された基板の被めっき面の周囲の上面に当接して基板の被めっき面を開放した状態でシールするシール部を有する堰部材と、前記堰部材で囲まれた基板の被めっき面に無電解めっき処理液を供給して溜める無電解めっき処理液供給手段とを具備することを特徴とする。この無電解めっき装置は、無電解めっき処理液として、前処理液、触媒処理液、無電解めっき液などを取り替えて使用することができ、一連の無電解めっき工程を単一セルで実施できる。
【００２０】
請求項８に記載の発明は、前記無電解めっき処理液供給手段は、被めっき面の上部に設置されて分散して無電解めっき処理液を供給するように構成されていることを特徴とする。
これによって基板の被めっき面全体に略均一に処理液を同時に供給できる。
【００２１】
請求項９に記載の発明は、前記基板の近傍に加熱手段を設けたことを特徴とする。加熱手段としては、例えば被めっき面を基板の下面側から加熱する裏面ヒータを設置したり、基板の上面側から加熱するランプヒータを設置したりすることである。
請求項１０に記載の発明は、前記加熱手段は前記保持手段の上方に設置されていることを特徴とする。
請求項１１に記載の発明は、前記使用後の無電解めっき処理液は、使い捨てにすることを特徴とする。
請求項１２に記載の発明は、前記無電解めっき装置は、基板を冷却する冷却手段を有していることを特徴とする。
【００２２】
【発明の実施の形態】
以下、本発明の実施形態を図面に基づいて詳細に説明する。この実施形態にかかる無電解めっき装置は、例えば半導体基板Ｗの表面に無電解銅めっきを施して、銅層からなるシード層や配線を形成するのに使用される。このめっき工程の一例を図１を参照して説明する。
【００２３】
半導体基板Ｗには、図１（ａ）に示すように、半導体素子が形成された基板１の導電層１ａの上にＳｉＯ₂からなる絶縁膜２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３と配線用の溝４が形成され、その上にＴｉＮ等からなるバリア層５、更にその上に無電解銅めっきによってシード層７が形成される。なおシード層７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７の上にこれを補強するために補助シード層を無電解銅めっきによって形成する場合もある。そして図１（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３及び溝４内に銅を充填させると共に、絶縁膜２上に銅層６を堆積させる。その後化学的機械的研磨（ＣＭＰ）により絶縁膜２上の銅層６を除去して、図１（ｃ）に示すようにコンタクトホール３および配線用の溝４に充填した銅層６の表面と絶縁膜２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８を形成する。
【００２４】
図２は本発明の一実施形態を用いて構成される無電解めっき装置の概略構成図である。同図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１１と、保持手段１１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（めっき液保持機構）３１と、堰部材３１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（無電解めっき処理液）を供給するシャワーヘッド（無電解めっき処理液（分散）供給手段）４１と、保持手段１１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５１と、排出された洗浄液等（めっき廃液）を回収する回収容器６１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６５と、前記保持手段１１を回転駆動するモータ（回転駆動手段）Ｍとを具備して構成されている。以下各部材について説明する。
【００２５】
保持手段１１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１３を設けている。この基板載置部１３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。一方基板載置部１３の裏面側には、面状であって半導体基板Ｗの被めっき面を下面側から暖めて保温する裏面ヒータ（加熱手段）１５が設置されている。この裏面ヒータ１５は例えばラバーヒータによって構成されている。この保持手段１１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。
【００２６】
堰部材３１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３３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。
【００２７】
シャワーヘッド４１は、先端に多数のノズルを設けることで、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５１は、ノズル５３から洗浄液を噴出する構造である。
【００２８】
めっき液回収ノズル６５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上面周縁部の堰部材３１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。
【００２９】
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１１を下降して堰部材３１との間に所定寸法の隙間を設け、基板載置部１３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。
【００３０】
次に保持手段１１を上昇して図示のようにその上面を堰部材３１の下面に当接し、同時に半導体基板Ｗの外周を堰部材３１のシール部３３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。
【００３１】
次に裏面ヒータ１５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４１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表面は堰部材３１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、この実施形態のように１ｍｍでも良い。本実施形態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。そしてこの実施形態においては、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、この実施形態における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、裏面ヒータ１５による半導体基板Ｗの保温は容易に行え、裏面ヒータ１５の容量は小さくて良く装置のコンパクト化が図れる。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。
【００３２】
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。
【００３３】
上記めっき処理が完了した後、めっき液回収ノズル６５の先端を半導体基板Ｗの表面周縁部の堰部材３１内側近傍に下降し、めっき液を吸い込む。このとき半導体ウエハ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３１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１１を下降して半導体基板Ｗを堰部材３１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５１のノズル５３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５３から噴射される洗浄液を堰部材３１にも当てることで堰部材３１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６１に回収され、廃棄される。
【００３４】
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６５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６１に回収しても良い。
【００３５】
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１１から取り出す。
【００３６】
図３は本発明の他の実施形態を用いて構成される無電解めっき装置の概略構成図である。同図において前記実施形態と相違する点は、保持手段１１内に裏面ヒータ１５を設ける代わりに、保持手段１１の上方にランプヒータ（加熱手段）１７を設置し、このランプヒータ１７とシャワーヘッド４１−２とを一体化した点である。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１７を同心円状に設置し、ランプヒータ１７の間の隙間からシャワーヘッド４１−２の多数のノズル４３−２をリング状に開口する。なおランプヒータ１７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。
【００３７】
このように構成してもめっき液は各ノズル４３−２から半導体基板Ｗの被めっき面上にシャワー状に略均等に供給でき、またランプヒータ１７によって半導体基板Ｗの加熱・保温も直接均一に行える。ランプヒータ１７の場合、半導体基板Ｗとめっき液の他に、その周囲の空気をも加熱するので半導体基板Ｗの保温効果もある。
【００３８】
なおランプヒータ１７によって半導体基板Ｗを直接加熱するには、比較的大きい消費電力のランプヒータ１７が必要になるので、その代わりに比較的小さい消費電力のランプヒータ１７と前記図１に示す裏面ヒータ１５とを併用して、半導体基板Ｗは主として裏面ヒータ１５によって加熱し、めっき液と周囲の空気の保温は主としてランプヒータ１７によって行うようにしても良い。また前述の実施例と同様に、半導体基板Ｗを直接、又は間接的に冷却する手段をも設けて、温度制御を行っても良い。
【００３９】
次に前記図２に示す無電解めっき装置と、図５に示す従来の無電解めっき装置とを用いて実際にめっきを行ってその結果を比較した。以下に実験の条件と結果を示す。
【００４０】
〔無電解Ｃｕめっき試料〕
φ８インチ半導体基板であってシリコンの上にＴａＮ（３０ｎｍ）のバリア層とＣｕ（５０ｎｍ）のシード層（ベタ膜）を形成したもの。
【００４１】
〔めっき仕様〕
（１）本願発明によるめっき方法
工程：裏面ヒータ１５（７０℃）によって加熱した保持手段１１に前記半導体基板Ｗをセットし、堰部材３１を半導体基板Ｗにセットした後、半導体基板Ｗを静止した状態でめっき液（５０℃）をシャワーヘッド４１から３０ｍｌだけ５ｓｅｃ間供給する。次に１００ｒｐｍで１ｓｅｃだけ半導体基板Ｗを回転し、めっき液を均一に半導体基板Ｗ面上に濡らし、静止状態で１ｍｉｎ間保持する。その後めっき液回収ノズル６５によってめっき液を回収してから堰部材３１を半導体基板Ｗ表面から離し、半導体基板Ｗを回転（８００ｒｐｍ）しながら、洗浄液（超純水）を半導体基板Ｗ面上に３０ｓｅｃ間供給して水洗いしめっき反応を停止させる。洗浄液の供給を停止して半導体基板Ｗをスピン乾燥（１０００ｒｐｍ、３０ｓｅｃ）して取り出す。
【００４２】
（２）従来例によるめっき方法
工程：保持手段８１に半導体基板Ｗをセットし、半導体基板Ｗを４０ｒｐｍで回転させながら７０℃のめっき液を半導体基板Ｗ中央に１ｍｉｎ（６００ｍｌ／ｍｉｎ）の間滴下し続ける。めっき液の滴下終了後、半導体基板Ｗの回転を継続しながら洗浄液（超純水）を半導体基板Ｗ面上に３０ｓｅｃ間供給することで水洗いしめっき反応を停止させる。そして保持手段８１から半導体基板Ｗを取り出して別途乾燥機にて乾燥する。
【００４３】
図４は以上各方法によって無電解メッキした半導体基板ＷのＸ軸上の膜厚を測定した結果を示す図である。同図に示すように本願発明によるめっき方法は半導体基板Ｗの全体にわたってその膜厚が均一になっているのに対して、従来例によるめっき方法では半導体基板Ｗ中央の膜厚が極端に薄くなっており、本願発明によるめっき方法の方がめっき膜厚の面内均一性が各段に向上することが確認できた。
【００４４】
以上本発明の実施形態を説明したが、本発明は上記実施形態に限定されるものではなく、特許請求の範囲、及び明細書と図面に記載された技術的思想の範囲内において種々の変形が可能である。例えば本発明にかかる無電解めっき装置は、シード層や配線用の銅層形成に限られず、配線保護膜形成などにも用いることができる。
【００４５】
さらに本発明にかかる無電解めっき装置は、無電解めっきの前処理工程や触媒処理工程にも用いることができる。即ち例えば上記実施形態ではシャワーヘッド４１から無電解めっき液を半導体基板Ｗの被めっき面に供給して無電解めっきを行わせたが、無電解めっき液の供給工程の前にシャワーヘッド４１から無電解めっきの前処理工程や触媒処理工程に用いる他の無電解めっき処理液を供給することで、これらの処理工程も無電解めっき工程と共にこの無電解めっき装置で行うことができる。
【００４６】
上記実施形態では被めっき面上にめっき液を保持して静止させた状態でメッキしたが、めっきムラが生じない程度にゆっくりと回転させても良い。
【００４７】
また被めっき面にめっき液を分散して供給可能であればシャワーヘッドに限ることはなく、例えば揺動動作又は並進動作を行いながらめっき液を供給するノズルを設けても良い。
【００４８】
上記実施形態ではめっき後の洗浄工程において保持手段１１を堰部材３１から引き離した状態で洗浄液を供給して洗浄を行ったが、保持手段１１を堰部材３１から引き離さない状態のまま洗浄液を供給し、洗浄液を堰部材３１の上部の淵からオーバーフローさせることでその洗浄を行っても良い。洗浄液の供給によって内部に残っためっき液が希釈化されると同時に液温が低下し、これによって無電解めっきの反応は停止する。なお保持手段１１を下降させる代わりに堰部材３１を引き上げることで両者を引き離しても良い。
【００４９】
上記裏面ヒータ１５によって半導体基板Ｗを加熱する際（特に加熱開始からめっき液を接液するまでの間）、半導体基板Ｗの被めっき面に酸化防止を目的に不活性ガス、例えばアルゴン（Ａｒ）ガスを吹き付けることが好ましい。半導体基板Ｗ表面に例えばスパッタ等によるシード層が露出している場合は、これが加熱されるとその表面が酸化する恐れがあるので、これを防止してより膜厚の均質なめっき層を前記シード層上に形成しようとするような場合に用いれば特に効果的である。
【００５０】
上記実施形態では半導体基板Ｗの加熱手段として裏面ヒータ１５やランプヒータ１７を用いたが、基板近傍のさらに他の位置にヒータを設置してもよい。またヒータを用いる代りに、又はヒータを用いると共に、無電解めっきを行なう雰囲気の温度を無電解めっき処理温度（反応面である被めっき面のめっきに好適な温度）とほぼ同等にすることで、放熱を防止して処理温度を一定に保つことができる。この場合は基板の周囲に加熱した気体を供給するなどすればよい。
【００５１】
上記実施形態では基板の被めっき面上に供給した無電解めっき処理液を接液させる工程として、基板を瞬時回転する工程を用いたが、その他にも、要は基板を動かすことや、供給した無電解めっき処理液を動かすことによって無電解めっき処理液を被めっき面全体に接液させる工程であればよい。即ち基板を動かす工程としては、例えば無電解めっき処理液が供給された基板を振動させることや、揺動させる（揺り動かす）こと等であり、供給した無電解めっき処理液を動かす工程としては、供給した無電解めっき処理液を掻き均し部材を用いて掻き均すことや、液面に送風すること等である。
【００５２】
上記実施形態では半導体基板に無電解めっきする例を示したが、半導体基板以外の各種基板に無電解めっきする場合にも適用できることは言うまでもない。
【００５３】
【発明の効果】
以上詳細に説明したように本発明によれば以下のような優れた効果を有する。▲１▼被めっき面上に無電解めっき処理液を所定時間溜めて保持することで被めっき面を処理するように構成したので、少量の無電解めっき処理液で被めっき面の処理が行え、コスト低減が図れ、また無電解めっき処理液供給用のポンプとして小型のものが使用でき、無電解めっき装置のコンパクト化が図れ、これを収納するクリーンルームコストの低減化も図れる。また使用する無電解めっき処理液が少量なので無電解めっき処理液の昇温・保温が容易で即座に行え、且つ大量の無電解めっき処理液を常時昇温させておく必要がないので無電解めっき処理液の劣化が促進されることもない。
【００５４】
▲２▼使用する無電解めっき処理液の量が少なくて良いので、そのまま廃棄してもコスト増加にはならず、常に新規な無電解めっき処理液を使用できて処理液組成を一定にでき、循環使用する場合に生じる副生成物などが系内に堆積せず安定なめっき等の処理が容易に行え、めっき液の液分析装置や液調整装置が不要になり、装置コストの低減化及びクリーンルームコストの低減化が図れる。また無電解めっき処理液を大量に循環使用しないので、各装置構成部材からパーティクルが発生しにくく、濾過装置が不要になる。
【００５５】
▲３▼無電解めっき処理液を被めっき面上に保持して処理を行うので、無電解めっき処理液を被めっき面上に滴下しながら処理を行う場合に比べて被めっき面の各部の処理条件を同一にでき、形成されるめっき膜厚の面内均一化が図れる。特に基板を静止させた状態で処理を行えば、基板を回転しながら処理を行う場合に比べて基板の周速による放熱が生じず、温度降下せずに反応温度の均一化が図れ、安定なプロセスが得られる。
【００５７】
(4)無電解めっき処理液供給手段を、被めっき面の上部に設置されて分散して無電解めっき処理液を供給するように構成した場合は、基板の被めっき面全体に略均一に無電解めっき処理液を同時に供給でき、無電解めっき処理液の温度制御が安定して行える。
【００５８】
(5)基板を保持する保持手段と、被めっき面の周囲をシールする堰部材と、堰部材で囲まれた基板の被めっき面に無電解めっき処理液を供給して溜める無電解めっき処理液供給手段とを具備して無電解めっき装置を構成したので、無電解めっき処理液として、前処理液、触媒処理液、無電解めっき液などを取り替えて使用することができ、従って一連の無電解めっき工程を単一セルで実施可能となり、装置のコンパクト化が図れる。
【図面の簡単な説明】
【図１】めっき工程の一例を示す図である。
【図２】本発明の一実施形態を用いて構成される無電解めっき装置の概略構成図である。
【図３】本発明の他の実施形態を用いて構成される無電解めっき装置の概略構成図である。
【図４】本願発明と従来例の各方法によって無電解めっきした半導体基板Ｗの膜厚測定結果を示す図である。
【図５】従来の無電解めっき装置の概略構成図である。
【符号の説明】
Ｗ半導体基板（基板）
１１保持手段（基板保持手段）
１３基板載置部
１５裏面ヒータ（加熱手段）
３１堰部材（めっき液保持機構）
３３シール部
４１シャワーヘッド（無電解めっき処理液供給手段）
５１洗浄液供給手段
５３ノズル
６１回収容器
６５めっき液回収ノズル
Ｍモータ
１７ランプヒータ（加熱手段）
４１−２シャワーヘッド
４３−２ノズル[0001]
BACKGROUND OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention is an electroless plating suitable for use in wiring formation of a semiconductor substrate (including formation of a seed layer and an auxiliary seed layer formed for the purpose of reinforcing the seed layer) and formation of a wiring protective film. It relates to a method and a device.
[0002]
[Prior art]
Conventionally, aluminum or an aluminum alloy has generally been used as a material for forming a wiring circuit on a semiconductor substrate. However, as the degree of integration increases, it is required to use a material having higher conductivity as the wiring material. . For this reason, a method has been proposed in which copper or an alloy thereof is used as a wiring material, and this is plated on a semiconductor substrate to fill a wiring pattern groove formed on the substrate.
[0003]
Various methods such as CVD (Chemical Vapor Deposition) and sputtering are known as a method for filling the wiring pattern groove with copper or an alloy thereof, but when the material of the metal layer is copper or an alloy thereof, that is, In the case of forming a copper wiring, the cost is high in CVD, and in the case of sputtering, there is a disadvantage that embedding is impossible when the aspect is high (the ratio of the depth of the pattern is large). This is because the plating method is most effective.
[0004]
On the other hand, in the electroless plating equipment, each of these processing steps is used instead of the electroless plating equipment that performs electroless plating processing by providing a plurality of units for performing the conventional plating process, the pretreatment process accompanying the plating, and the cleaning process. There has been proposed an electroless plating apparatus that performs this in one unit. FIG. 5 is a diagram showing a schematic configuration of this type of electroless plating apparatus. As shown in the figure, in this electroless plating apparatus, a cover 83 is installed around a semiconductor substrate W placed and fixed on a holding means 81 that is rotationally driven by a motor M, and the semiconductor substrate W is indicated by a dotted line. The plating solution is supplied from the plating tank 87 to the upper center of the semiconductor substrate W by the pump P while being rotated by the motor M at the position, and the plating solution is spread over the entire upper surface of the semiconductor substrate W by the centrifugal force by the rotation. The plating solution dropped from the semiconductor substrate W is returned from the plating solution recovery part 85 of the cover 83 to the plating tank 87 and circulated.
[0005]
On the other hand, the semiconductor substrate W after plating is lowered and rotated to a position indicated by a solid line in the drawing, and by supplying cleaning water from a cleaning water supply means (not shown), the plating solution is washed away from the surface to the cleaning liquid recovery unit 86. Collect and drain.
[0006]
However, the conventional electroless plating apparatus has the following various problems.
(1) Since the plating solution is constantly dripped onto the surface to be plated of the semiconductor substrate, a large amount of the plating solution is circulated and used. In addition, when a large amount of plating solution is circulated and used, a large pump is required, and a liquid temperature maintenance device against the liquid temperature rise due to the heat generated by the pump is required, which not only increases the cost of the device but also increases the size of the device, and thus stores this device. Clean room costs will increase.
[0007]
(2) Since the plating solution is constantly circulated, by-products accumulate in the system due to the principle of electroless plating, and a stable plating process cannot be maintained. Further, in order to obtain a stable plating process, a plating solution analysis and solution adjusting device is required, which causes an increase in device cost and an increase in clean room cost.
[0008]
{Circle around (3)} Since the plating solution is circulated and used in large quantities, particles are likely to be generated from the respective constituent members of the apparatus, and it is necessary to install the filtering device F in the circulation path, resulting in an increase in apparatus cost and clean room cost.
[0009]
(4) When plating is performed while supplying the plating solution to only one place on the surface to be plated, the plating thickness of the portion where the plating solution has been dripped is thinner than the plating thickness of the other portions. Has been confirmed by experiments, and the in-plane uniformity of film thickness deteriorates. This is considered to be because only the portion where the plating solution is dropped is different in the reaction state due to the difference in the flow rate and thickness of the plating solution compared to the other portions.
[0010]
(5) In order to perform electroless plating, it is necessary to maintain the temperature of the reaction surface between the surface to be plated and the plating solution at a predetermined constant temperature, so a large amount of plating solution is optimal for the plating reaction. A procedure for constantly raising the temperature to the temperature is required, resulting in an increase in apparatus cost and an increase in clean room cost, and since the plating solution is always raised in temperature, the deterioration of the plating solution is promoted.
[0011]
{Circle around (6)} Since the semiconductor substrate is always rotated, the temperature drop becomes noticeable due to heat dissipation due to the peripheral speed of the semiconductor substrate, and a stable plating process cannot be obtained.
[0012]
(7) If the plating solution is to be supplied to the surface to be plated by spraying instead of dropping, the temperature control of the plating solution is uncertain and a stable plating process cannot be obtained.
[0013]
[Problems to be solved by the invention]
The present invention has been made in view of the above points, and its purpose is to reduce the amount of plating solution used, maintain a stable plating process, reduce the size and cost of the apparatus, and improve the film thickness. It is an object of the present invention to provide an electroless plating method and apparatus capable of achieving uniformity in the inside and preventing deterioration of the plating solution due to temperature rise.
[0014]
[Means for Solving the Problems]
  In order to solve the above problems, the invention described in claim 1The to-be-plated surface of the substrate is faced upward, and a weir member that surrounds the to-be-plated surface is opened on the to-be-plated surface,Supplying an electroless plating solution on the surface to be plated of the substrate, and performing an electroless plating process by holding the electroless plating solution on the surface to be plated for a predetermined timeWhenIs performed continuously. As a result, the surface to be plated can be treated with a small amount of electroless plating solution, a small pump can be used as a supply pump for the electroless plating solution, and the electroless plating equipment can be made compact and a clean room for storing it. Costs can be reduced. Moreover, since the electroless plating solution used is small, the temperature of the electroless plating solution can be easily raised and kept warm.
  The invention described in claim 2 is characterized in that the depth of the electroless plating solution held on the surface to be plated of the substrate is 10 mm or less.
[0015]
  Claim3The invention described in 1 is between the step of supplying the electroless plating treatment liquid and the step of holding the electroless plating treatment solution on the surface to be plated of the substrate for a predetermined time and performing the electroless plating treatment The electroless plating solution supplied on the surface to be plated of the substrateOver the entire surface to be platedA step of contacting the liquid is provided. As the step of bringing the electroless plating solution supplied to a part of the surface of the substrate into contact with the entire surface to be plated, the substrate is moved [ie, for example, the substrate supplied with the electroless plating solution is rotated. , Vibrating, swinging (moving), etc.] and moving the supplied electroless plating solution (scraping using a scraping member, blowing air to the liquid level, etc.) It is.
  The invention described in claim 4 is characterized in that the step of bringing the electroless plating solution into contact with the entire surface to be plated is a step of rotating the substrate for a time of 10 seconds or less.
[0016]
  Claim5According to the invention described in (2), the step of storing the electroless plating treatment liquid on the surface to be plated of the substrate for a predetermined time and holding the electroless plating treatmentAnd plating solutionIs performed in a stationary state. With this configuration, heat radiation due to the peripheral speed of the substrate does not occur as compared with the case where the processing is performed while rotating the substrate, the reaction temperature of each part can be made uniform, and a stable process can be obtained.
[0017]
  Claim6The invention described inInert gas is blown onto the surface to be plated until the electroless plating solution is in contact with the surface to be plated on the substrate.It is characterized by that.
[0019]
  Claim7The holding means for holding the substrate with the surface to be plated facing upward, and the periphery of the surface to be plated of the substrate held by the holding meansA dam member having a seal portion that seals with the upper surface of the substrate in contact with the surface to be plated openAnd saidSurrounded by weir membersAn electroless plating solution supply means for supplying and storing the electroless plating solution on the surface to be plated of the substrate is provided. This electroless plating apparatus can be used by replacing a pretreatment liquid, a catalyst treatment liquid, an electroless plating liquid, and the like as an electroless plating treatment liquid, and a series of electroless plating processes can be performed in a single cell.
[0020]
  Claim8The invention described inThe electroless plating treatment liquid supply means is configured to be installed at an upper portion of the surface to be plated and to distribute and supply the electroless plating treatment liquid.It is characterized by that.
As a result, the processing liquid can be simultaneously supplied substantially uniformly to the entire surface to be plated of the substrate.
[0021]
  Claim9The invention described in item 1 is characterized in that a heating means is provided in the vicinity of the substrate. As the heating means, for example, a back heater for heating the surface to be plated from the lower surface side of the substrate, or a lamp heater for heating from the upper surface side of the substrate is installed.
  The invention described in claim 10 is characterized in that the heating means is installed above the holding means.
  The invention described in claim 11 is characterized in that the electroless plating solution after use is disposable.
  The invention described in claim 12 is characterized in that the electroless plating apparatus has a cooling means for cooling the substrate.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The electroless plating apparatus according to this embodiment is used to form a seed layer or wiring made of a copper layer by performing electroless copper plating on the surface of a semiconductor substrate W, for example. An example of this plating process will be described with reference to FIG.
[0023]
As shown in FIG. 1A, the semiconductor substrate W is made of SiO on the conductive layer 1a of the substrate 1 on which the semiconductor element is formed.₂The contact hole 3 and the wiring groove 4 are formed by lithography / etching technique, the barrier layer 5 made of TiN or the like is further formed thereon, and the seed layer 7 is formed thereon by electroless copper plating. Is formed. The seed layer 7 may be formed in advance by sputtering or the like, and an auxiliary seed layer may be formed on the seed layer 7 by electroless copper plating in order to reinforce it. Then, as shown in FIG. 1B, the surface of the semiconductor substrate W is plated with copper so that the contact holes 3 and the grooves 4 of the semiconductor substrate W are filled with copper, and a copper layer 6 is deposited on the insulating film 2. . Thereafter, the copper layer 6 on the insulating film 2 is removed by chemical mechanical polishing (CMP), and the surface of the copper layer 6 filled in the contact hole 3 and the wiring groove 4 as shown in FIG. The surface of the insulating film 2 is made substantially flush with the surface of the insulating film 2, and a wiring protective film 8 is formed on the exposed metal surface.
[0024]
FIG. 2 is a schematic configuration diagram of an electroless plating apparatus configured using one embodiment of the present invention. As shown in the figure, this electroless plating apparatus has a holding means 11 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 11. A weir member (plating solution holding mechanism) 31 that abuts the peripheral portion and seals the peripheral portion, and a plating solution (electroless plating treatment solution) on the surface to be plated of the semiconductor substrate W whose peripheral portion is sealed by the dam member 31 ) A shower head (electroless plating treatment liquid (dispersion) supply means) 41, a cleaning liquid supply means 51 installed near the upper periphery of the holding means 11 and supplying a cleaning liquid to the surface to be plated of the semiconductor substrate W; A recovery container 61 for recovering the discharged cleaning liquid (plating waste liquid), a plating liquid recovery nozzle 65 for sucking and recovering the plating liquid held on the semiconductor substrate W, and a mode for driving the holding means 11 to rotate. It is constructed (rotation driving means) to and a M. Each member will be described below.
[0025]
The holding means 11 is provided with a substrate mounting portion 13 for mounting and holding the semiconductor substrate W on the upper surface thereof. The substrate placement unit 13 is configured to place and fix the semiconductor substrate W. Specifically, a vacuum suction mechanism (not shown) that vacuum-sucks the semiconductor substrate W to the back side thereof is installed. On the other hand, on the back surface side of the substrate mounting portion 13, a back surface heater (heating means) 15 that is planar and warms the plated surface of the semiconductor substrate W from the lower surface side is installed. The back heater 15 is constituted by a rubber heater, for example. The holding means 11 is rotationally driven by a motor M and is configured to be moved up and down by an elevating means (not shown).
[0026]
The weir member 31 has a cylindrical shape, and a seal portion 33 for sealing the outer peripheral edge of the semiconductor substrate W is provided at the lower portion thereof, and is installed so as not to move up and down from the illustrated position.
[0027]
The shower head 41 has a structure in which 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 by providing a number of nozzles at the tip. The cleaning liquid supply means 51 has a structure for ejecting the cleaning liquid from the nozzle 53.
[0028]
The plating solution recovery nozzle 65 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 31 on the peripheral surface of the upper surface of the semiconductor substrate W so as to suck the plating solution on the semiconductor substrate W. Has been.
[0029]
Next, the operation of this electroless plating apparatus will be described. First, the holding means 11 is lowered from the state shown in the figure to provide a gap with a predetermined dimension between the weir member 31 and the semiconductor substrate W is placed and fixed on the substrate platform 13. For example, a φ8 inch wafer is used as the semiconductor substrate W.
[0030]
Next, the holding means 11 is raised and its upper surface is brought into contact with the lower surface of the dam member 31 as shown in the figure, and at the same time, the outer periphery of the semiconductor substrate W is sealed by the seal portion 33 of the dam member 31. At this time, the surface of the semiconductor substrate W is in an open state.
[0031]
Next, the semiconductor substrate W itself is directly heated by the back surface heater 15 to, for example, set the temperature of the semiconductor substrate W to 70 ° C. (maintain until the end of plating), and then a plating solution heated to, for example, 50 ° C. is ejected from the shower head 41. Then, 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 31, 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 a small amount so as to be 1 mm thick (about 30 ml) on the surface of the semiconductor substrate W. The depth of the plating solution held on the surface to be plated may be 10 mm or less, and may be 1 mm as in this embodiment. If a small amount of plating solution is supplied as in this embodiment, the heating device for heating the plating solution can be small. In this embodiment, 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. The temperature can be optimized for the reaction. 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 back heater 15 can be easily performed. The capacity is small and the device 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.
[0032]
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.
[0033]
After the plating process is completed, the tip of the plating solution recovery nozzle 65 is lowered to the vicinity of the inside of the weir member 31 at the peripheral edge of the surface of the semiconductor substrate W, and the plating solution is sucked. At this time, if the semiconductor wafer 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 31 at 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 11 is lowered to separate the semiconductor substrate W from the weir member 31, the rotation of the semiconductor substrate W is started, and the cleaning liquid (ultra pure water) is supplied from the nozzle 53 of the cleaning liquid supply means 51 to the surface to be plated of the semiconductor substrate W. 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 53 may be applied to the weir member 31 to simultaneously clean the weir member 31. The plating waste liquid at this time is collected in the collection container 61 and discarded.
[0034]
The plating solution that has been used once is not reused but is 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 65 may not be installed, and the used plating solution may be recovered in the recovery container 61 as a plating waste solution together with the cleaning solution.
[0035]
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 11.
[0036]
FIG. 3 is a schematic configuration diagram of an electroless plating apparatus configured using another embodiment of the present invention. In the figure, the difference from the above embodiment is that a lamp heater (heating means) 17 is installed above the holding means 11 instead of providing the back heater 15 in the holding means 11, and the lamp heater 17 and the shower head 41. -2. That is, for example, a plurality of ring-shaped lamp heaters 17 having different radii are installed concentrically, and a large number of nozzles 43-2 of the shower head 41-2 are opened in a ring shape from the gaps between the lamp heaters 17. The lamp heater 17 may be composed of a single spiral lamp heater, or may be composed of lamp heaters having various other structures and arrangements.
[0037]
Even with this configuration, the plating solution can be supplied almost uniformly in a shower form from the nozzles 43-2 onto the surface to be plated of the semiconductor substrate W, and the heating and heat insulation of the semiconductor substrate W can be directly and uniformly performed by the lamp heater 17. Yes. In the case of the lamp heater 17, in addition to the semiconductor substrate W and the plating solution, the surrounding air is also heated, so that there is an effect of keeping the temperature of the semiconductor substrate W.
[0038]
In order to directly heat the semiconductor substrate W by the lamp heater 17, the lamp heater 17 with relatively high power consumption is required. Instead, the lamp heater 17 with relatively low power consumption and the back surface heater shown in FIG. 15, the semiconductor substrate W may be heated mainly by the back heater 15, and the plating solution and the surrounding air may be kept warm mainly by the lamp heater 17. Similarly to the above-described embodiment, a temperature control may be performed by providing a means for cooling the semiconductor substrate W directly or indirectly.
[0039]
Next, plating was actually performed using the electroless plating apparatus shown in FIG. 2 and the conventional electroless plating apparatus shown in FIG. 5, and the results were compared. The experimental conditions and results are shown below.
[0040]
[Electroless Cu plating sample]
A φ8 inch semiconductor substrate in which a TaN (30 nm) barrier layer and a Cu (50 nm) seed layer (solid film) are formed on silicon.
[0041]
[Plating specifications]
(1) Plating method according to the present invention
Step: The semiconductor substrate W is set on the holding means 11 heated by the back heater 15 (70 ° C.), the weir member 31 is set on the semiconductor substrate W, and then the plating solution (50 ° C.) with the semiconductor substrate W stationary. Is supplied from the shower head 41 by 30 ml for 5 sec. Next, the semiconductor substrate W is rotated for 1 second at 100 rpm, the plating solution is uniformly wetted on the surface of the semiconductor substrate W, and is held for 1 minute in a stationary state. Thereafter, the plating solution is recovered by the plating solution recovery nozzle 65, and then the weir member 31 is separated from the surface of the semiconductor substrate W, and the cleaning solution (ultra pure water) is applied to the surface of the semiconductor substrate W for 30 sec while rotating the semiconductor substrate W (800 rpm). Supply for a while and rinse with water to stop the plating reaction. The supply of the cleaning liquid is stopped, and the semiconductor substrate W is taken out by spin drying (1000 rpm, 30 sec).
[0042]
(2) Conventional plating method
Step: The semiconductor substrate W is set on the holding means 81, and the plating solution at 70 ° C. is continuously dropped onto the center of the semiconductor substrate W for 1 min (600 ml / min) while rotating the semiconductor substrate W at 40 rpm. After the dropping of the plating solution, the cleaning solution (ultra-pure water) is supplied onto the surface of the semiconductor substrate W for 30 seconds while the semiconductor substrate W continues to rotate, and the plating reaction is stopped. Then, the semiconductor substrate W is taken out from the holding means 81 and dried by a separate dryer.
[0043]
FIG. 4 is a diagram showing the results of measuring the film thickness on the X-axis of the semiconductor substrate W electrolessly plated by the above methods. As shown in the figure, the film thickness of the plating method according to the present invention is uniform over the entire semiconductor substrate W, whereas the film thickness at the center of the semiconductor substrate W is extremely thin in the conventional plating method. It was confirmed that the in-plane uniformity of the plating film thickness was improved in each step by the plating method according to the present invention.
[0044]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims and the specification and drawings. Is possible. For example, the electroless plating apparatus according to the present invention is not limited to the formation of a seed layer or a copper layer for wiring, but can also be used for forming a wiring protective film.
[0045]
Furthermore, the electroless plating apparatus according to the present invention can also be used for a pretreatment step and a catalyst treatment step of electroless plating. That is, for example, in the above embodiment, the electroless plating solution is supplied from the shower head 41 to the surface to be plated of the semiconductor substrate W to perform the electroless plating. However, the electroless plating solution is supplied from the shower head 41 before the electroless plating solution supply step. By supplying other electroless plating solution used for the electroplating pretreatment step and the catalyst treatment step, these treatment steps can be performed in the electroless plating apparatus together with the electroless plating step.
[0046]
In the above-described embodiment, plating is performed in a state where the plating solution is held on the surface to be plated and is stationary, but may be slowly rotated to such an extent that uneven plating does not occur.
[0047]
In addition, the present invention is not limited to the shower head as long as the plating solution can be distributed and supplied to the surface to be plated. For example, a nozzle that supplies the plating solution while performing a swinging operation or a translation operation may be provided.
[0048]
In the above-described embodiment, cleaning is performed by supplying the cleaning liquid in a state in which the holding unit 11 is separated from the dam member 31 in the cleaning step after plating. However, the cleaning liquid is supplied in a state in which the holding unit 11 is not separated from the dam member 31. The cleaning may be performed by overflowing the cleaning liquid from the top of the weir member 31. By supplying the cleaning solution, the plating solution remaining in the interior is diluted, and at the same time, the solution temperature is lowered, whereby the electroless plating reaction is stopped. Instead of lowering the holding means 11, the weir member 31 may be pulled up to separate them.
[0049]
When the semiconductor substrate W is heated by the back heater 15 (especially from the start of heating until the plating solution is contacted), an inert gas such as argon (Ar) is used to prevent oxidation on the surface to be plated of the semiconductor substrate W. It is preferable to blow gas. If a seed layer by sputtering, for example, is exposed on the surface of the semiconductor substrate W, the surface may be oxidized if it is heated. It is particularly effective when used in a case where it is intended to be formed on a layer.
[0050]
In the above embodiment, the back heater 15 and the lamp heater 17 are used as the heating means for the semiconductor substrate W. However, a heater may be installed at another position near the substrate. In addition to using a heater or using a heater, the temperature of the atmosphere in which electroless plating is performed is substantially equal to the electroless plating temperature (temperature suitable for plating the surface to be plated, which is the reaction surface). Heat treatment can be prevented and the processing temperature can be kept constant. In this case, a heated gas may be supplied around the substrate.
[0051]
In the above embodiment, the step of instantaneously rotating the substrate was used as the step of contacting the electroless plating solution supplied onto the surface to be plated of the substrate. Any process may be used as long as the electroless plating solution is in contact with the entire surface to be plated by moving the electroless plating solution. That is, the process of moving the substrate includes, for example, vibrating the substrate supplied with the electroless plating solution, or shaking (moving) the substrate, and the process of moving the supplied electroless plating solution. For example, the electroless plating solution may be scraped and leveled using a leveling member, or may be blown to the liquid level.
[0052]
In the above-described embodiment, an example in which electroless plating is performed on a semiconductor substrate has been shown, but it goes without saying that the present invention can also be applied to the case where electroless plating is performed on various substrates other than the semiconductor substrate.
[0053]
【The invention's effect】
As described in detail above, the present invention has the following excellent effects. (1) Since the surface to be plated is treated by storing and holding the electroless plating solution on the surface to be plated for a predetermined time, the surface to be plated can be treated with a small amount of electroless plating solution, The cost can be reduced, and a small pump can be used as a supply pump for the electroless plating treatment solution, so that the electroless plating apparatus can be made compact and the cost of the clean room for housing it can be reduced. In addition, since the electroless plating solution used is small, the electroless plating solution can be easily heated and kept warm, and there is no need to constantly heat up a large amount of the electroless plating solution. Deterioration of the processing liquid is not promoted.
[0054]
(2) Since the amount of electroless plating solution to be used may be small, it does not increase the cost even if it is discarded as it is, and a new electroless plating solution can always be used and the composition of the treatment solution can be made constant. By-products generated in the case of recycling do not accumulate in the system, and stable plating and other processing can be performed easily, eliminating the need for plating solution analyzers and solutions, reducing equipment costs and clean rooms Cost can be reduced. Further, since the electroless plating solution is not circulated and used in large quantities, it is difficult for particles to be generated from the constituent members of each device, and a filtering device is not required.
[0055]
(3) Since the treatment is performed by holding the electroless plating solution on the surface to be plated, each part of the surface to be plated is treated as compared with the case where the treatment is performed while the electroless plating solution is dropped on the surface to be plated. The conditions can be made the same, and the in-plane uniformity of the formed plating film thickness can be achieved. In particular, when the process is performed while the substrate is stationary, heat is not radiated due to the peripheral speed of the substrate as compared with the case where the process is performed while the substrate is rotated, and the reaction temperature can be made uniform without a temperature drop. A process is obtained.
[0057]
  (Four)If the electroless plating solution supply means is installed at the top of the surface to be plated and dispersed to supply the electroless plating solution, the electroless plating treatment is applied almost uniformly to the entire surface of the substrate to be plated. The solution can be supplied simultaneously, and the temperature control of the electroless plating solution can be performed stably.
[0058]
  (Five)The holding means for holding the substrate and the periphery of the surface to be plated are sealed.Weir memberWhen,Weir membersoSurroundedSince the electroless plating apparatus comprises an electroless plating treatment liquid supply means for supplying and storing the electroless plating treatment liquid on the surface to be plated of the substrate, the pretreatment liquid as the electroless plating treatment liquid, The catalyst treatment solution, electroless plating solution, and the like can be used interchangeably. Therefore, a series of electroless plating steps can be performed in a single cell, and the apparatus can be made compact.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a plating process.
FIG. 2 is a schematic configuration diagram of an electroless plating apparatus configured using an embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of an electroless plating apparatus configured using another embodiment of the present invention.
FIG. 4 is a diagram showing a film thickness measurement result of a semiconductor substrate W electrolessly plated by each method of the present invention and the conventional example.
FIG. 5 is a schematic configuration diagram of a conventional electroless plating apparatus.
[Explanation of symbols]
W Semiconductor substrate (substrate)
11 Holding means (substrate holding means)
13 Substrate placement part
15 Back heater (heating means)
31 Weir member (Plating solution holding mechanism)
33 Sealing part
41 Shower head (electroless plating solution supply means)
51 Cleaning liquid supply means
53 nozzles
61 Collection container
65 Plating solution recovery nozzle
M motor
17 Lamp heater (heating means)
41-2 Shower head
43-2 Nozzle

Claims

The surface to be plated of the substrate faces upward, and the dam member surrounding the surface to be plated is brought into contact with the surface to be plated, and the electroless plating process is performed on the surface to be plated of the substrate surrounded by the dam member electroless that the step of supplying a liquid, and performing the electroless plating treatment liquid was held sump predetermined time on the surface to be plated of the substrate by electroless plating, and performing in succession Plating method.

2. The electroless plating method according to claim 1, wherein the depth of the electroless plating treatment liquid retained on the surface to be plated of the substrate is 10 mm or less.

Between the step of supplying the electroless plating solution and the step of storing and holding the electroless plating solution on the surface of the substrate for a predetermined time to perform the electroless plating treatment, 3. The electroless plating method according to claim 1, further comprising a step of bringing the electroless plating solution supplied onto the plating surface into contact with the entire surface to be plated .

The electroless plating method according to claim 3, wherein the step of bringing the electroless plating solution into contact with the entire surface to be plated is a step of rotating the substrate for a time of 10 seconds or less.

2. The step of storing and holding the electroless plating solution on the surface to be plated of the substrate for a predetermined time and performing the electroless plating treatment is performed in a state where the substrate and the plating solution are stationary. The electroless plating method according to 2 or 3 or 4 .

6. The electroless plating according to any one of claims 1 to 5, wherein an inert gas is blown onto the surface to be plated before the electroless plating solution is contacted on the surface to be plated of the substrate. Method.

Holding means for holding the substrate with the surface to be plated facing upward;
A dam member having a seal portion that seals in a state where the surface to be plated of the substrate is in contact with the upper surface around the surface to be plated of the substrate held by the holding means; and
An electroless plating apparatus comprising: an electroless plating solution supply means for supplying and storing an electroless plating solution on a surface to be plated of the substrate surrounded by the dam member .

8. The electroless plating process according to claim 7, wherein the electroless plating solution supply means is installed on an upper surface of the surface to be plated and dispersed to supply the electroless plating solution. apparatus.

The electroless plating apparatus according to claim 7, wherein a heating unit is provided in the vicinity of the substrate.

The electroless plating apparatus according to claim 9, wherein the heating unit is installed above the holding unit.

The electroless plating apparatus according to any one of claims 7 to 10, wherein the electroless plating solution after use is disposable.

The electroless plating apparatus according to any one of claims 7 to 11, wherein the electroless plating apparatus has a cooling means for cooling the substrate.