JP3883802B2

JP3883802B2 - Electroless plating equipment

Info

Publication number: JP3883802B2
Application number: JP2000327798A
Authority: JP
Inventors: 裕章井上; 浩二三島; 努狩俣; 憲二中村; 守治松本
Original assignee: Ebara Corp
Current assignee: Ebara Corp
Priority date: 2000-10-26
Filing date: 2000-10-26
Publication date: 2007-02-21
Anticipated expiration: 2020-10-26
Also published as: JP2002129344A

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）や配線保護膜形成や拡散防止膜形成などに用いて好適な無電解めっき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７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、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内側周囲をシールするめっき液保持機構と、前記めっき液保持機構でシールさ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、前記保持手段内に設置されて基板全体を加熱する加熱手段と、前記加熱手段の温度を制御する温度制御手段とを具備し、前記加熱手段は複数のゾーンに分割されると共に、前記温度制御手段によって各ゾーン毎に温度制御され、さらに前記加熱手段と前記基板の間の保持手段の内部に中空の均一温度形成部を設け、この均一温度形成部の内部に液体又は気体を充填し、さらに充填した液体又は気体の入れ替え用の配管とポンプを取り付けたことを特徴とする。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。さらに加熱手段と基板の間に気体又は液体を満たす均一温度形成部を設けたので、加熱手段として例えば線状ヒータをリング状（渦巻状）に配置したもののように面の場所によって温度にバラツキが生じる加熱手段を用いたとしても、均一温度形成部において面全体を同一温度にすることができ、基板の各部の加熱温度を均一化できる。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。
【００１５】
保持手段に保持して加熱された基板の冷却速度は各部で異なる場合が多く、通常基板の外周から冷えていく。このような場合はこの発明のように、加熱手段を複数のゾーンに分割して各ゾーン毎に温度制御することが好ましい。例えば加熱手段を基板中央に対向するゾーンと外周部に対向するゾーンに分割し、外周部に対向するゾーンの温度を基板中央に対向するゾーンの温度よりも高めにすることで、基板全体の温度を均一化する。
【００１６】
請求項２に記載の発明は、前記無電解めっき処理液が供給された基板の上を覆う蓋部材を具備することを特徴とする。無電解めっき処理中の基板上に蓋部材を載せることで、無電解めっき処理液の蒸発、気流発生に伴う放熱を抑制でき、より効果的な基板のめっきが行なえる。蓋部材は無電解めっき処理液の液面と接触しても良いし、接触しなくても良い。
請求項３に記載の発明は、前記均一温度形成部の内径は、基板の直径よりも小さいことを特徴とする。
【００１７】
請求項４に記載の発明は、前記無電解めっき処理液供給手段が、基板の被めっき面の上部に設置され、且つ前記無電解めっき処理液を供給された基板の上を覆う形状に形成することで蓋部材を兼用していることを特徴とする。無電解めっき処理液供給手段に蓋部材を兼用させることにより、装置のコンパクト化・低コスト化が図れる。
【００１８】
請求項５に記載の発明は、前記無電解めっき装置に、基板の被めっき面に溜めた無電解めっき処理液を吸引回収する機構を設けたことを特徴とする。
【００１９】
【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。
【００２０】
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。
【００２１】
図２は本発明の参考例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。
【００２２】
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。そしてこの保持手段１１はその上面を半導体基板Ｗを載置して保持する基板載置部１３としている。この基板載置部１３には半導体基板Ｗが載置されて固定されるように構成されているが、基板載置部１３の半導体基板Ｗを載置する部分には円形で半導体ウエハＷの直径よりも少し小さい内径の凹状の均一温度形成部１７が設けられている。均一温度形成部１７の中央と周囲の所定位置にはそれぞれ温度センサ１４が埋め込まれている。これら温度センサ１４は対向する半導体基板Ｗの裏面温度を検知する例えば赤外線検知センサによって構成されている。一方保持手段１１内部の均一温度形成部１７の下側には、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）１５−１，１５−２が設置されている。裏面ヒータ１５−１，２は図３に示すように中央に設置される円板形状の裏面ヒータ１５−１と、その周囲を囲むように設置されるリング状の裏面ヒータ１５−２によって構成されている。これら裏面ヒータ１５−１，２は例えばラバーヒータによって構成されており、図３に示す温度制御手段２０によってそれぞれ所定の温度となるように制御されている。温度制御手段２０には前記各温度センサ１４からの温度検知信号が入力される。
【００２３】
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。
【００２４】
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。供給されるめっき液は、めっきに好適な温度（例えば５０℃）に加熱されていることが好ましい。このためめっき液供給源からシャワーヘッド（めっき液供給手段）４１までの配管は、保温性の高い部材を用いることが好ましい。例えば配管を二重管構造にして中央の通路にめっき液を通し、外側の通路に保温部材（例えば所定温度（例えば５０℃）に昇温した空気等の気体や水，温水等の液体等）を充填するなどである。昇温した気体や液体を充填した場合は、めっき液供給源でのめっき液温度が低くても配管中で加熱され、シャワーヘッド４１に到ったときはめっきに好適な温度まで上昇させることができる。一方洗浄液供給手段５１は、ノズル５３から洗浄液を噴出する構造である。
【００２５】
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。
【００２６】
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上に半導体基板Ｗを載置・固定する。このとき均一温度形成部１７は塞がれる。半導体基板Ｗとしては例えばφ８インチウエハを用いる。
【００２７】
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。
【００２８】
次に裏面ヒータ１５（１５−１，２）によって半導体基板Ｗを空気層からなる均一温度形成部１７を介して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。各裏面ヒータ１５−１，１５−２の加熱温度は、各温度センサ１４が検出した半導体ウエハＷの各部の温度に応じて図３に示す温度制御手段２０が制御する。例えば半導体基板Ｗは通常中央部分よりも外周端の方が冷え易いが、そのような場合は裏面ヒータ１５−２の加熱温度を裏面ヒータ１５−１の加熱温度よりも少し高くなるようにし、これによって半導体基板Ｗの保温温度を各部均一に保つ。
【００２９】
次に半導体基板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、この参考例のように１ｍｍでも良い。本参考例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。そしてこの参考例においては、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、この参考例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自体を加熱手段によって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組成変化の防止が図れ、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。
【００３０】
一方本参考例においては、裏面ヒータ１５と半導体基板Ｗの間に気体を満たす隙間（空間）からなる均一温度形成部１７を設けているが、均一温度形成部１７の熱容量は大きいので、たとえ裏面ヒータ１５の表面温度にバラツキがある場合でも、均一温度形成部１７の各部の温度は均一温度になり、半導体ウエハＷの裏面を精度良く均一温度に加熱できる。なおこの参考例においては気体として空気を用いたが、不活性ガス等の他の各種気体であっても良い。
【００３１】
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。
【００３２】
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。
【００３３】
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。
【００３４】
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。
【００３５】
図４は本発明の他の参考例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。なお説明の都合上、図２に示した洗浄液供給手段５１とめっき液回収ノズル６５の記載は省略している。この参考例において図２に示す参考例と相違する点は、半導体基板Ｗの上を覆う蓋部材２５を設置した点のみである。この蓋部材２５は堰部材３１の上面を塞ぐ位置と、塞がない位置とで移動自在に構成されており、通常は堰部材３１の上面を塞がない位置にあり、シャワーヘッド４１によって半導体ウエハＷ上にめっき液が供給された後に堰部材３１の上面を塞ぐ図示の位置に移動する。
【００３６】
めっき液が供給された半導体ウエハＷ上を蓋部材２５で覆うことで、めっき液の蒸発、気流発生に伴う放熱を抑制でき、無電解めっき時の温度管理をより容易且つ精度良く行うことができる。なおこの参考例では半導体ウエハＷ上のめっき液と蓋部材２５との間に空間を設けているが、両者は接触しても良い（通常はめっき液の温度変化を防止するために両者は接触させない方が良い）。
【００３７】
図５は本発明のさらに他の参考例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。この図においても図２に示す洗浄液供給手段５１とめっき液回収ノズル６５の記載は省略している。この参考例において図４に示す参考例と相違する点は、蓋部材２５を独立した部材として設けず、シャワーヘッド４１に蓋部材２５を兼用させた点である。すなわち半導体基板Ｗの被めっき面の上部に位置するシャワーヘッド４１を上下動自在に構成し、且つシャワーヘッド４１の外周に板状の張り出し部２６を設けることでシャワーヘッド４１自体を半導体基板Ｗの上を覆う蓋部材２５とした。このように構成すれば、別途蓋部材２５を設置しなくても良いので、装置のコンパクト化、低コスト化が図れる。
【００３８】
図６は本発明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。この図に示す実施形態において前記図２に示す参考例と相違する点は、凹状の均一温度形成部１７を設ける代りに、保持手段１１の内部に中空の均一温度形成部１７を設け、その内部に液体（例えば水）を充填した点である。このように構成しても、裏面ヒータ１５と半導体基板Ｗの間に熱容量の大きい液体を満たす隙間（空間）からなる均一温度形成部１７が形成されるので、たとえ裏面ヒータ１５の表面温度にバラツキがある場合でも、均一温度形成部１７において各部の温度を均一温度にでき、半導体ウエハＷの裏面を精度良く均一温度に加熱できる。なおこの実施形態においては均一温度形成部１７内に水等の液体を充填したが、空気等の気体を充填しても良い。またこの中空の均一温度形成部１７内の液体を外部に引き出す配管とポンプを取り付けることによって、液体の入れ替えなどを行うようにしても良い。その場合供給する液体温度は所定の温度に昇温させておくことが好ましい。
【００３９】
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、配線保護膜形成や拡散防止膜形成などにも用いることができる。
【００４０】
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。
【００４１】
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。
【００４２】
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。
【００４３】
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。
【００４４】
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。
【００４５】
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を用いたが、基板近傍の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。
【００４６】
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。
【００４７】
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。
【００４８】
【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。
【００４９】
▲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。
【００５０】
▲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。
【００５１】
(4)加熱手段と基板の間に均一温度形成部を設けたので、加熱手段としてその表面の温度にバラツキのある加熱手段を用いたとしても、均一温度形成部においてその全体を同一温度にすることができ、基板の各部の加熱温度を均一化できる。
【００５２】
▲５▼加熱手段を複数のゾーンに分割し、各ゾーン毎に温度制御するように構成したので、基板全体の温度の均一化を図ることができる。
【００５３】
▲６▼無電解めっき処理液を供給した基板の上を蓋部材で覆うように構成したので、無電解めっき処理液の蒸発、気流発生に伴う放熱を抑制でき、より効果的な基板のめっきが行なえる。特に無電解めっき処理液供給手段自体に蓋部材を兼用させれば、装置のコンパクト化・低コスト化が図れる。
【００５４】
▲７▼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】本発明の参考例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】裏面ヒータ１５−１，１５−２の平面図である。
【図４】本発明の他の参考例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５】本発明の他の参考例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６】本発明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７】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）
１７均一温度形成部（隙間）
２０温度制御手段
２５蓋部材
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[0001]
BACKGROUND OF THE INVENTION
The present invention is used for 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), wiring protection film formation, diffusion prevention film formation, and the like. The present invention relates to a suitable electroless plating apparatus.
[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. 7 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. 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 will be 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 apparatus that can achieve uniformity inside and prevent deterioration of the plating solution due to temperature rise.
[0014]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is characterized in that the holding means for holding the substrate with the surface to be plated facing upward, and plating for sealing the inner periphery of the surface to be plated of the substrate held by the holding means. A liquid holding mechanism, an electroless plating solution supplying means for supplying and storing an electroless plating solution on the surface of the substrate sealed by the plating solution holding mechanism, and the entire substrate installed in the holding means. A heating means for heating; and a temperature control means for controlling the temperature of the heating means. The heating means is divided into a plurality of zones, and the temperature is controlled for each zone by the temperature control means. A hollow uniform temperature forming part is provided inside the holding means between the heating means and the substrate, the liquid or gas is filled inside the uniform temperature forming part, and the filled liquid or gas is replaced. Characterized in that fitted with tubes and pumps. 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. Since further provided a uniform temperature forming unit that meets a gas or liquid between the heating means and the substrate, variations in temperature depending on the location of the surface as for example the linear heater as a heating means that are arranged in a ring shape (spiral) even with heating means occurs, the entire Oite surface can be the same temperature uniform temperature forming portion can equalize the heating temperature of each part of the substrate. The electroless plating equipment as an electroless plating treatment liquid, the pretreatment liquid, the catalyst treatment solution, replace the electroless plating solution can be used, it can be a series of electroless plating process in a single cell .
[0015]
The cooling rate of the substrate held and heated by the holding means is often different in each part, and usually cools from the outer periphery of the substrate. In such a case, it is preferable to control the temperature for each zone by dividing the heating means into a plurality of zones as in the present invention. For example, the heating means is divided into a zone facing the center of the substrate and a zone facing the outer periphery, and the temperature of the zone facing the outer periphery is made higher than the temperature of the zone facing the center of the substrate. Homogenize.
[0016]
The invention described in claim 2 is characterized by comprising a lid member that covers the substrate supplied with the electroless plating solution. By placing the lid member on the substrate during the electroless plating process, it is possible to suppress the heat dissipation due to the evaporation of the electroless plating solution and the generation of the air current, and more effective substrate plating can be performed. The lid member may or may not contact the liquid surface of the electroless plating solution.
The invention described in claim 3 is characterized in that an inner diameter of the uniform temperature forming portion is smaller than a diameter of the substrate.
[0017]
According to a fourth aspect of the present invention, the electroless plating solution supplying means is formed in a shape that is installed on an upper surface of the substrate to be plated and covers the substrate supplied with the electroless plating solution. Thus, the lid member is also used. By making the electroless plating treatment solution supply means also serve as a lid member, it is possible to reduce the size and cost of the apparatus.
[0018]
The invention according to claim 5 is characterized in that the electroless plating apparatus is provided with a mechanism for sucking and collecting the electroless plating solution stored on the surface to be plated of the substrate.
[0019]
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.
[0020]
The semiconductor the substrate W, as shown in FIG. 1 (a), an insulating film 2 made of SiO ₂ is deposited on a conductive layer 1a of the substrate 1 on which semiconductor devices are formed, a contact hole 3 by a lithographic etching technique A wiring groove 4 is formed, a barrier layer 5 made of TiN or the like is formed thereon, and a seed layer 7 is formed thereon by electroless copper plating. 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.
[0021]
FIG. 2 is a schematic configuration diagram of an electroless plating apparatus configured using a reference example 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.
[0022]
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). The holding means 11 has a top surface serving as a substrate mounting portion 13 for mounting and holding the semiconductor substrate W. Although the semiconductor substrate W is mounted and fixed on the substrate mounting portion 13, the portion of the substrate mounting portion 13 on which the semiconductor substrate W is mounted is circular and has a diameter of the semiconductor wafer W. A concave uniform temperature forming portion 17 having an inner diameter slightly smaller than that is provided. Temperature sensors 14 are embedded at predetermined positions around the center and the periphery of the uniform temperature forming unit 17. These temperature sensors 14 are constituted by, for example, infrared detection sensors that detect the back surface temperature of the semiconductor substrate W facing the temperature sensors 14. On the other hand, on the lower side of the uniform temperature forming portion 17 inside the holding means 11, back surface heaters (heating means) 15-1 and 15-2 for keeping the surface to be plated of the semiconductor substrate W warm from the lower surface side are installed. . As shown in FIG. 3, the back heaters 15-1 and 15-2 are composed of a disc-shaped back heater 15-1 installed at the center and a ring-shaped back heater 15-2 installed so as to surround the periphery. ing. These backside heaters 15-1 and 15-2 are composed of, for example, rubber heaters, and are controlled to have predetermined temperatures by the temperature control means 20 shown in FIG. A temperature detection signal from each temperature sensor 14 is input to the temperature control means 20.
[0023]
The weir member 31 has a cylindrical shape, and a seal portion 33 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.
[0024]
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 supplied plating solution is preferably heated to a temperature suitable for plating (for example, 50 ° C.). For this reason, it is preferable that the piping from the plating solution supply source to the shower head (plating solution supply means) 41 uses a member having high heat retention. For example, the pipe is made into a double pipe structure, the plating solution is passed through the central passage, and the heat retaining member (eg, gas such as air heated to a predetermined temperature (eg, 50 ° C.), water, liquid such as hot water) is passed through the outer passage. And so on. When the heated gas or liquid is filled, even if the plating solution temperature at the plating solution supply source is low, it is heated in the pipe, and when it reaches the shower head 41, it can be raised to a temperature suitable for plating. it can. On the other hand, the cleaning liquid supply means 51 has a structure for ejecting the cleaning liquid from the nozzle 53.
[0025]
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 edge of the upper surface of the semiconductor substrate W to suck the plating solution on the semiconductor substrate W. Has been.
[0026]
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. At this time, the uniform temperature forming portion 17 is blocked. For example, a φ8 inch wafer is used as the semiconductor substrate W.
[0027]
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.
[0028]
Next, the semiconductor substrate W is heated by the back surface heater 15 (15-1, 2) through the uniform temperature forming unit 17 made of an air layer, for example, the temperature of the semiconductor substrate W is set to 70 ° C. (maintained until the end of plating). Next, a plating solution heated to, for example, 50 ° C. is ejected from the shower head 41 to pour the plating solution over substantially the entire surface of the semiconductor substrate W. 3 is controlled by the temperature control means 20 shown in FIG. 3 according to the temperature of each part of the semiconductor wafer W detected by each temperature sensor 14. For example, the semiconductor substrate W is usually easier to cool at the outer peripheral edge than the central portion. In such a case, the heating temperature of the back heater 15-2 is set slightly higher than the heating temperature of the back heater 15-1. Thus, the temperature of the semiconductor substrate W is kept uniform in each part.
[0029]
Next, 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 retained on the surface to be plated may be 10 mm or less, and may be 1 mm as in this reference example . If a small amount of plating solution is supplied as in this reference example , the heating device for heating the plating solution can be small. And in this reference example, the temperature of the semiconductor substrate W to 70 ° C., since the temperature of the plating solution was heated to 50 ° C., the surface to be plated of the semiconductor substrate W becomes, for example, 60 ° C., plating in this Example The temperature can be optimized for the reaction. If the semiconductor substrate W itself is configured to be heated by the heating means in this way, the temperature of the plating solution that requires high power consumption for heating does not need to be raised so high, so that power consumption can be reduced. In addition, the composition change of the plating solution can be prevented, which is preferable. 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.
[0030]
On the other hand, in the present reference example , the uniform temperature forming unit 17 including a gap (space) that fills the gas is provided between the back surface heater 15 and the semiconductor substrate W, but the heat capacity of the uniform temperature forming unit 17 is large. Even when the surface temperature of the heater 15 varies, the temperature of each part of the uniform temperature forming unit 17 becomes a uniform temperature, and the back surface of the semiconductor wafer W can be accurately heated to a uniform temperature. In this reference example , air is used as a gas, but other various gases such as an inert gas may be used.
[0031]
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.
[0032]
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 on the peripheral edge of the semiconductor substrate W by 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.
[0033]
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.
[0034]
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.
[0035]
FIG. 4 is a schematic configuration diagram of an electroless plating apparatus configured using another reference example of the present invention. For convenience of explanation, the description of the cleaning solution supply means 51 and the plating solution recovery nozzle 65 shown in FIG. 2 is omitted. This reference example is different from the reference example shown in FIG. 2 only in that a lid member 25 that covers the semiconductor substrate W is provided. The lid member 25 is configured to be movable between a position where the upper surface of the dam member 31 is blocked and a position where the upper surface of the dam member 31 is not blocked. Usually, the lid member 25 is located at a position where the upper surface of the dam member 31 is not blocked. After the plating solution is supplied onto W, the plate moves to the position shown in the figure to block the upper surface of the dam member 31.
[0036]
By covering the semiconductor wafer W supplied with the plating solution with the lid member 25, it is possible to suppress the heat dissipation due to the evaporation of the plating solution and the generation of the air current, and the temperature management during the electroless plating can be performed more easily and accurately. . In this reference example , a space is provided between the plating solution on the semiconductor wafer W and the lid member 25, but both may be in contact with each other (normally, both are in contact with each other in order to prevent the temperature of the plating solution from changing). It ’s better not to let them.)
[0037]
FIG. 5 is a schematic configuration diagram of an electroless plating apparatus configured using still another reference example of the present invention. Also in this figure, the description of the cleaning solution supply means 51 and the plating solution recovery nozzle 65 shown in FIG. 2 is omitted. This reference example is different from the reference example shown in FIG. 4 in that the lid member 25 is not provided as an independent member, and the shower head 41 is also used as the lid member 25. That is, the shower head 41 located above the surface to be plated of the semiconductor substrate W is configured to be movable up and down, and the shower head 41 itself is attached to the semiconductor substrate W by providing a plate-like protruding portion 26 on the outer periphery of the shower head 41. The lid member 25 covering the top was used. If comprised in this way, since it is not necessary to install the cover member 25 separately, the compactness of an apparatus and cost reduction can be achieved.
[0038]
FIG. 6 is a schematic configuration diagram of an electroless plating apparatus configured using the embodiment of the present invention. In the embodiment shown in this figure, the difference from the reference example shown in FIG. 2 is that instead of providing the concave uniform temperature forming portion 17, a hollow uniform temperature forming portion 17 is provided inside the holding means 11, Is filled with a liquid (for example, water). Even in this configuration, since the uniform temperature forming portion 17 is formed between the back heater 15 and the semiconductor substrate W and is formed with a gap (space) that fills the liquid with a large heat capacity, the surface temperature of the back heater 15 varies. Even if there is, the temperature of each part can be made uniform in the uniform temperature forming part 17, and the back surface of the semiconductor wafer W can be accurately heated to the uniform temperature. In this embodiment, the uniform temperature forming unit 17 is filled with a liquid such as water, but may be filled with a gas such as air. Further, by replacing the liquid in the hollow uniform temperature forming unit 17 with a pipe and a pump for drawing the liquid to the outside, the liquid may be replaced. In that case, the liquid temperature to be supplied is preferably raised to a predetermined temperature.
[0039]
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 or a diffusion prevention film.
[0040]
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.
[0041]
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.
[0042]
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.
[0043]
In the above embodiment, cleaning is performed by supplying the cleaning liquid while the holding means 11 is separated from the weir member 31 in the cleaning step after plating. However, the cleaning liquid is supplied while the holding means 11 is not separated from the weir 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 inside is diluted, and at the same time, the temperature of the solution 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.
[0044]
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.
[0045]
In the above embodiment, the back heater 15 is used as a heating means for the semiconductor substrate W, but a heater may be installed at another position near the substrate. In addition to using a heater, the temperature of the atmosphere in which electroless plating is performed is made substantially equal to the electroless plating temperature (temperature suitable for plating of the surface to be plated, which is the reaction surface), thereby preventing heat dissipation and processing temperature. Can be kept constant. In this case, a heated gas may be supplied around the substrate.
[0046]
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.
[0047]
In the above-described embodiment, an example in which electroless plating is performed on a semiconductor substrate has been shown, but it is needless to say that the present invention can also be applied to the case where electroless plating is performed on various substrates other than the semiconductor substrate.
[0048]
【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.
[0049]
(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 each device constituent member, and a filtration device is not required.
[0050]
(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.
[0051]
(4) Since the uniform temperature forming section is provided between the heating means and the substrate, even if a heating means having a variation in the surface temperature is used as the heating means, the uniform temperature forming section has the same temperature throughout. The heating temperature of each part of the substrate can be made uniform.
[0052]
(5) Since the heating means is divided into a plurality of zones and the temperature is controlled for each zone, the temperature of the entire substrate can be made uniform.
[0053]
(6) Since the top of the substrate supplied with the electroless plating solution is covered with a lid member, the evaporation of the electroless plating solution and the heat dissipation associated with the generation of airflow can be suppressed, and more effective substrate plating can be achieved. Yes. In particular, if the electroless plating solution supply means itself is also used as a lid member, it is possible to reduce the size and cost of the apparatus.
[0054]
(7) As the electroless plating solution, the pretreatment solution, catalyst treatment solution, electroless plating solution, etc. can be used interchangeably. Therefore, a series of electroless plating processes can be performed in a single cell. Compactness can be achieved.
[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 a reference example of the present invention.
FIG. 3 is a plan view of backside heaters 15-1 and 15-2.
FIG. 4 is a schematic configuration diagram of an electroless plating apparatus configured using another reference example of the present invention.
FIG. 5 is a schematic configuration diagram of an electroless plating apparatus configured using another reference example of the present invention.
FIG. 6 is a schematic configuration diagram of an electroless plating apparatus configured using an embodiment of the present invention.
FIG. 7 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 placing part 15 Back surface heater (heating means)
17 Uniform temperature forming part (gap)
20 Temperature control means 25 Lid member 31 Weir member (plating solution holding mechanism)
33 Seal part 41 Shower head (electroless plating solution supply means)
51 Cleaning solution supply means 53 Nozzle 61 Recovery container 65 Plating solution recovery nozzle M Motor

Claims

Holding means for holding the substrate with the surface to be plated facing upward;
A plating solution holding mechanism for sealing the inner periphery of the surface to be plated of the substrate held by the holding means;
An electroless plating solution supply means for supplying and storing the electroless plating solution on the surface to be plated of the substrate sealed by the plating solution holding mechanism;
A heating means installed in the holding means for heating the entire substrate;
Temperature control means for controlling the temperature of the heating means,
The heating means is divided into a plurality of zones, and the temperature is controlled for each zone by the temperature control means,
Further, a hollow uniform temperature forming part is provided inside the holding means between the heating means and the substrate, and the liquid or gas is filled in the uniform temperature forming part, and the filled liquid or gas replacement pipe is further provided. And electroless plating equipment, which is equipped with a pump .

The electroless plating apparatus according to claim 1, further comprising a lid member that covers the substrate supplied with the electroless plating solution.

The electroless plating apparatus according to claim 1, wherein an inner diameter of the uniform temperature forming portion is smaller than a diameter of the substrate.

The electroless plating solution supply means is installed on the upper surface of the substrate to be plated, and also serves as a lid member by forming a shape covering the substrate supplied with the electroless plating solution. The electroless plating apparatus according to claim 2 .

The electroless plating apparatus according to claim 1, 2, 3, or 4, wherein the electroless plating apparatus is provided with a mechanism for sucking and collecting the electroless plating treatment liquid collected on the surface to be plated of the substrate.