JP4346737B2

JP4346737B2 - Thin film forming equipment

Info

Publication number: JP4346737B2
Application number: JP20316799A
Authority: JP
Inventors: 和人岡田; 裕彦福元; 和志林; 利彰高橋; 耕一長田; 明光中上; 勇藏森
Original assignee: Kobe Steel Ltd
Current assignee: Kobe Steel Ltd
Priority date: 1999-07-16
Filing date: 1999-07-16
Publication date: 2009-10-21
Anticipated expiration: 2019-07-16
Also published as: JP2001026876A

Description

【０００１】
【発明の属する技術分野】
本発明は、プラズマによる化学反応を利用して基板上にアモルファスシリコン等からなる薄膜を形成する薄膜形成装置に関するものである。
【０００２】
【従来の技術】
近年、前記のようなプラズマ式の薄膜形成装置として、高速回転する電極を基板上に対向させるものが開発されるに至っている（例えば特開平９−１０４９８５号公報参照）。その装置の概要を図８及び図９に示す。
【０００３】
図８において、密閉されたチャンバ１０内には、基板搬送台１２が設置され、その上に基板１４が載置されるとともに、これら基板搬送台１２及び基板１４はアースに接続されている。そして、この基板１４と僅かな隙間をもって対向するように電極１８が配設されている。この電極１８は、図の奥行き方向に延びる略円柱状をなし、その中心を回転軸１６が貫いており、この回転軸１６の両端が図略の支柱により回転可能に支持されている。回転軸１６の端部はチャンバ外面の高周波電極端子１９に電気的に接続され、この高周波電極端子１９が図略の高周波電源に接続されている。
【０００４】
この装置において、チャンバ１０内を排気し、電極１８を回転させながらこれに高周波電力または直流電力を印加して当該電極１８と基板１４との間にプラズマ２２を発生させるとともに、図略の反応ガス供給源から反応ガス（図例ではＳｉＨ₄とＨ₂との混合ガス）及び希釈ガス（例えばＨｅ）をチャンバ１０内に導入すると、これらのガスは電極１８の回転によって当該電極１８と基板１４との間に巻き込まれてプラズマ２２に導かれ、ここで前記反応ガスが化学反応を起こす。このような化学反応を起こさせながら基板１４を基板搬送台１２とともに所定方向（電極１８の回転軸方向と直交する方向）に走査する結果、図９に示すように、基板１４上に薄膜（図例ではアモルファスシリコンからなる薄膜）２３が形成される。
【０００５】
この装置は、均一な薄膜２３を大面積の領域に高速で連続的に形成することを可能にするとともに、従来では困難とされていた１気圧以上の圧力下でのグロー放電プラズマ発生を可能にする画期的な手段であるが、このように高圧下でしかも高速で成膜を行うと、反応ガスの分解反応が気相で急激に起こることに起因して、図９に示すように成膜２３に寄与しなかったシリコン原子が相互に結びついてパーティクル（微粒子）２４を形成することになる。このようなパーティクル２４が基板１４上に堆積すると、成膜２３の表面形態を乱し、高品質膜の形成を阻害する要因となる。
【０００６】
そこで、前記公報には、電極回転方向の下流側に図１０（ａ）（ｂ）に示すようなダクト９０を配置し、このダクト９０を通じてパーティクル２４を吸引除去するようにしたものが開示されている。このダクト９０は、その先端の吸引口９２が他の部分よりも狭小の先細り状に形成され、その吸引口９２が電極１８の回転方向下流側において当該電極１８の外周面と基板１４の上面との隙間に挿入されている。この吸引口９２におけるガス吸引速度としては、電極表面の周速度と同等の速度以上であって、好ましくは電極表面の周速度の２倍以上、より好ましくは１０倍以上であるとされている。
【０００７】
【発明が解決しようとする課題】
図１１は、前記ダクト９０の近傍におけるガスの流れ状態を示したものである。この図に示されるように、従来のダクト構造及び配置では次のような不都合が存在する。
【０００８】
・ダクト９０の上面と電極１８の外周面との間や、ダクト９０の下面と基板１４の上面との間には必ず隙間が存在するため、この隙間を通じてもダクト吸引口９２へガスが吸引され、その分、電極１８の近傍でのガス吸引速度が低下する。従って、前記吸引口９２を電極１８に近づけ、かつ吸引口９２での吸引速度を高くしても、電極近傍でのガス吸引速度を上げるには限界があり、当該電極近傍におけるパーティクルの有効な除去が行いにくい。
【０００９】
・パーティクルは、その全てが気流に同伴するぐらい小径のパーティクルであるとは限らず、慣性力によって電極１８の円周接線方向に飛散するような大径のパーティクル（図１１に示すパーティクル２４ｂ）も存在する。また、パーティクル２４は、必ずしも気相中から下流側（ダクト９０側）へ運ばれるとは限らず、一旦電極１８の表面に付着してから基板１４より大きく離れた位置で剥離し、再飛散することもある。これらのパーティクルは、前記先細ダクト９０によっては有効に捕集することができない。
【００１０】
・ダクト吸引口９２にはパーティクル２４を含むガスが正面から衝突するため、その近傍にパーティクルが堆積しやすく（図１１に示すパーティクル２４ｃ）、このようなパーティクル２４ｃが堆積したダクト自体が汚染源となるおそれがある。
【００１１】
・高速回転電極１８に引きずられた当該電極周方向へのガスの流れと、当該電極１８とダクト９０との隙間から吸引されるガスの流れとが交錯することにより、プラズマ２２の発生領域から遠くない位置で渦Ｗが形成されてしまう。この渦Ｗは、活性な反応中間体あるいはそれらのクラスターを長時間滞留させ、パーティクルの成長を促す要因となる。
【００１２】
・基板１４の上面とダクト９０との隙間から吸引されるガスの流れに起因して、基板１４の近傍に流れの淀み域９４が形成される。この淀み域９４も、前記渦Ｗと同様、活性な反応中間体あるいはそれらのクラスターを長時間滞留させ、パーティクルの成長を促す要因となる。
【００１３】
本発明は、このような事情に鑑み、ダクトのパーティクル除去性能を高めることにより、基板上にパーティクルが堆積するのを有効に抑止して高品質膜の高速形成を可能にする薄膜形成装置を提供することを目的とする。
【００１４】
【課題を解決するための手段】
前記課題を解決するための手段として、本発明は、回転する電極を基板に対向させて両者間にプラズマを発生させながら、前記プラズマに反応ガスを供給して化学反応を起こさせることにより前記基板上に薄膜を形成する薄膜形成装置において、前記電極の回転方向下流側に微粒子を吸引除去するためのダクトを設置するとともに、このダクトの吸引口形状を、前記電極の外周面のうち、前記基板と最狭隙間部を形成する最狭隙間形成部分の近傍位置から、当該最狭隙間形成部分よりも４５°以上１３５°以下だけ電極回転方向下流側の位置までの領域を覆う形状としたものである。
【００１５】
この構成によれば、従来のように電極外周面と基板との間に先細ダクトを挿入するのではなく、ダクト吸引口を広げて当該吸引口が電極の所定部分を覆うようにダクトを配置しているので、気流に同伴する小径のパーティクル（微粒子）から、慣性力により回転電極円周接線方向に飛散する大径のパーティクルに至るまで、前記ダクトによって効果的に捕集することができる。
【００１６】
ここで、前記電極外周面がダクトにより覆われる領域を、前記基板と最狭隙間部を形成する最狭隙間形成部分の近傍位置から、当該最狭隙間形成部分よりも４５°以上１３５°以下だけ電極回転方向下流側の位置までの領域としているのは、４５°未満であると、ダクトによる電極のカバー領域が小さすぎて従来の先細ダクトとパーティクル吸引効果の差が小さく、逆に１３５°を超えると、ダクトの流路断面積が大きくなりすぎてダクト内のガス流れが不安定になるとともに非定常な循環流が発生しやすくなり、特に電極回転数が高い条件では回転電極表面にパーティクルが堆積するおそれがあるためである。
【００１７】
なお、本発明においても、ダクト内壁にパーティクルが衝突する可能性はあるが、かかるパーティクルは比較的大きなものに限られ、壁面への付着力は弱い。しかも、従来の先細ダクトに比べてダクト内壁に対するパーティクル衝突フラックス（単位時間、単位面積当たりにダクト内壁に飛来する微粒子の数）は大幅に少ないため、ダクト内壁へのパーティクル付着度合いは極めて低く、かかる内壁が汚染源となるおそれもない。
【００１８】
この装置では、前記ダクトの吸引口上端と電極外周面との間に形成された隙間のガス流路抵抗と、前記ダクトの吸引口下端部から吸込まれるガスの流れ抵抗とがほぼ等しくなるようにダクトを配置するのが、より好ましい。この構成にすれば、ダクトの吸引口上端と下端との双方から良好なバランスでガスが吸引される。このうち、ダクトの吸引口上端と電極外周面との間に形成された隙間からダクト内に吸引されるガス（比較的清浄なガス）は、高速回転電極に引きずられたガスと対向するものであり、電極表面近傍のパーティクルを含むガスの多くを掻き取り、効果的にダクト内へと導く。これにより、パーティクル除去作用が高められる。さらに、ダクト端部については、そこから吸引されるガスによるパージ効果で、パーティクルの付着が抑制される。
【００１９】
なお、前記ダクトの吸引口上端と電極外周面との間に形成された隙間からダクト内に吸引されるガスは、高速回転電極に引きずられたガスと対向することによりダクト内側で循環流（渦）を形成するが、この渦はプラズマ発生領域及び基板表面から十分離れているため、基板上の薄膜に悪影響を与えるおそれはない。
【００２０】
本発明において、ダクトの具体的な形状は種々設定が可能である。例えば、前記ダクトを前記電極の両側面の一部を側方から覆う形状にしてもよいし、前記ダクトをその左右両側壁が前記電極の外周面に沿ってこれと対向する形状にしてもよい。前者の場合、前記電極の両側面とダクトとの間に形成される隙間のガス流路抵抗が、前記ダクトの吸引口下端部から吸込まれるガスの流れ抵抗や、前記ダクトの吸引口上端と電極外周面との間に形成された隙間のガス流路抵抗よりも大きくなるように当該電極の両側面とダクトとの間に形成される隙間を小さくすることにより、パーティクル除去に寄与しない無駄なガスの吸引を抑制でき、ダクトによるパーティクル吸引効果をさらに高めることができる。後者の場合も、前記ダクトの左右両側壁の端面と電極外周面との間に形成される隙間のガス流路抵抗が、前記ダクトの吸引口下端部から吸込まれるガスの流れ抵抗や、前記ダクトの吸引口上端と電極外周面との間に形成された隙間のガス流路抵抗よりも大きくなるように当該ダクト両側壁と電極外周面との間に形成される隙間を小さくすることにより、パーティクル除去に寄与しない無駄なガスの吸引を抑制でき、ダクトによるパーティクル吸引効果をさらに高めることができる。
【００２１】
また、本発明では、前記ダクトを基板上面または基板載置面に向かって開口する形状とし、この基板上面または基板載置面と前記ダクトとでガス吸引通路が形成されるように構成することにより、前記図１１に示したような流れの淀み域９４や渦Ｗが基板近傍で発生するのを完全に阻止することができ、パーティクル除去効果をさらに高めることができる。
【００２２】
具体的には、前記ダクトの側壁下端面と基板上面または基板載置面とを対向させるようにしてもよいし、前記ダクトの側壁と基板搬送台の側面とを対向させる（すなわちダクトの側壁を基板搬送台の側方に被せるように配置する）ようにしてもよい。いずれの場合も、前記ダクト両側壁下端面と基板上面または基板載置面とで形成される隙間のガス流路抵抗や、前記ダクト両側壁と基板搬送台側面とで形成される隙間のガス流路抵抗が、前記ダクトの吸引口下端部から吸込まれるガスの流れ抵抗や前記ダクトの吸引口上端と電極外周面との間に形成された隙間のガス流路抵抗よりも大きくなるようにすることにより、パーティクル除去に寄与しない無駄なガスの吸引を抑制でき、ダクトによるパーティクル吸引効果をさらに高めることができる。
【００２３】
【発明の実施の形態】
以下、本発明の好ましい実施の形態を図面に基づいて説明する。なお、これらの実施の形態で示す薄膜形成装置の基本原理及び基本構成は前記図８及び図９に示したものと同等であるので、これらの図に示した構成要素と同等の構成要素には同一の参照符を付してその説明を省略する。ただし、本発明において形成する薄膜材料は前記のアモルファスシリコンに限られず、例えばＣ、ＳｉＣ、ＳｉＯ２など、プラズマを利用した化学反応により薄膜を形成できる材料に広く適用が可能である。
【００２４】
１）第１の実施の形態（図１）
この実施の形態は、基板搬送台１２の幅が電極１８の幅（軸方向寸法）及び基板１４の幅よりも大きい場合に好適なものである。
【００２５】
図示のダクト３０は、水平壁３１及び傾斜壁３２からなる天壁と、この天壁の左右両側部から下方に延びる一対の側壁３３とを有し、下方に開口する形状をなしている。傾斜壁３２は、水平壁３１から離れるに従って低くなる方向に傾斜している。両側壁３３の下端面は水平であり、基板搬送台１２の上面（基板載置面）との間に微小隙間ｃをおいて対向し、これと平行となるようにダクト３０が配置されている。すなわち、このダクト３０と基板搬送台１２の上面とでガス吸引通路が形成されており、前記電極１８と反対側の開口３５が排気口とされ、これに図略のポンプが接続されている。また、基板１４は両側壁３３の内側を通るようになっている。
【００２６】
なお、基板１４の幅が基板搬送台１２の幅と同程度まで大きい場合には、基板１４の上面と側壁３３との間に微小隙間ｃを確保し、基板上面とダクト３０とでガス吸引通路を形成すればよい。
【００２７】
水平壁３１の前端部には、矩形状の切欠３４が形成され、この切欠３４内に電極１８が侵入するような位置関係でダクト３０が配設されている。従って、電極１８の軸方向両側面はダクト３０によって側方から一部覆われた状態となっている。ただし、両側壁３３の前端部には、電極回転軸１６との干渉を避けるための円弧状の切欠３３ａが形成されている。
【００２８】
このダクト３０の吸引口によって電極１８の外周面が覆われる領域は、電極１８と基板１４との最狭隙間部δの近傍位置（図２の例では最狭隙間部δよりも若干電極回転方向下流側の位置；この位置は最狭隙間部δよりも若干電極回転方向上流側の位置であってもよい。）から、前記最狭隙間部δよりも所定角度α（図では約９０°）だけ下流側の位置までの領域に設定されている。角度αの好適な範囲については後述する。
【００２９】
また、この装置における各隙間寸法は、次のように設定されている。
【００３０】
・切欠３４における水平壁３１の端面（ダクト吸引口上端）と電極１８の外周面との隙間ａ…当該隙間ａにおけるガス流路抵抗が、ダクト吸引口下端部から吸引されるガスの流れ抵抗と略等しくなるように隙間ａの寸法及び水平壁３１の厚み寸法を設定する。ここで、「ダクト吸引口下端部から吸引されるガスの流れ抵抗」とは、図２に示す構造の場合、基板１４の上面と電極１８との最狭隙間部δと、電極１８の外周面と、側壁３３の端面とで囲まれる隙間ｄにより形成される電極幅方向のガス吸引流路の抵抗と、前記最狭隙間部δにより形成される電極周方向のガス吸引流路の抵抗とを合成した流れ抵抗を意味する。もし、ダクト３０の前端が最狭隙間部δよりも電極回転方向上流側に位置していて前記隙間ｄによる流路が存在しない場合には、最狭隙間部δにより形成される電極周方向の流路の流れ抵抗そのものを意味することになる。
【００３１】
・電極１８の両側面と水平壁３１の端面との隙間ｂ…これらの隙間ｂにおけるガス流路抵抗の合成抵抗が、前記隙間ａにおけるガス流路抵抗や、ダクト吸引口下端部から吸引されるガスの流れ抵抗よりも大きくなる程度まで隙間ｂを小さくする。
【００３２】
・側壁３３の下端面と基板搬送台１２の上面との隙間ｃ…これらの隙間ｃにおけるガス流路抵抗の合成抵抗が、前記隙間ａにおけるガス流路抵抗や、ダクト吸引口下端部から吸引されるガスの流れ抵抗よりも大きくなる程度まで隙間ｃを小さくする。
【００３３】
この装置において、前記排気口３５からダクト３０内のガスを吸引することにより、次のような作用効果を得ることができる。
【００３４】
▲１▼ ダクト３０の吸引口が電極１８の外周面を比較的広範囲（図例では約１／４）にわたって覆っているので、図４（ａ）（ｂ）に示すように、ダクト内の気流に同伴する小径パーティクル２４ａから、慣性力により回転電極円周接線方向に飛散する大径パーティクル２４ｂに至るまで、効果的に捕集することができる。
【００３５】
ここで、前記図２に示した角度α（最狭隙間部δを形成する位置から水平壁３１に至るまでの領域に対応する電極１８の中心角）は、４５°以上１３５°未満、より好ましくは略９０°に設定することが好ましい。角度αが４５°未満であると、ダクト３０による電極１８のカバー領域が小さすぎて従来の先細ダクトと比べてパーティクル吸引効果の差が小さくなり、逆に１３５°を超えると、ダクト３０の流路断面積が大きくなりすぎてダクト内のガス流れが不安定になるとともに非定常な循環流が発生しやすくなり、特に電極回転数が高い条件では当該電極１８の表面にパーティクルが堆積するおそれがあるためである。
【００３６】
▲２▼ ダクト内壁に衝突するパーティクルの数（ダクト内壁に対するパーティクル衝突フラックス）は従来の先細ダクトに比べて非常に少なく、しかも、当該内壁に衝突するパーティクルは比較的大径のもの（図示のパーティクル２４ｂ）に限られていて当該ダクト内壁への付着力が小さいため、ダクト内壁に付着するパーティクルの量は非常に少なく、これが汚染源となることがない。
【００３７】
▲３▼ ダクト３０の底壁を省略してダクト全体が下向きに開口する形状にし、基板１４の上面及び基板搬送台１２の上面（基板載置面）をガス吸引通路の形成部材として兼用するようにしているので、従来のように底壁をもつダクトと異なり、基板１４の上面近傍に前記図１１に示したような流れの淀み域９４や渦（循環流）Ｗが発生せず、これらの淀み域９４や渦Ｗに起因する基板上へのパーティクルの堆積を防ぐことができる。
【００３８】
▲４▼ 水平壁３１の端面と電極１８の外周面との隙間ａを通じて、ダクト３０の外部から内部へ比較的清浄なガスが流入する。このガスは、回転電極１８の回転に引きずられて動くガス流とは逆向きの流れであり、電極表面近傍のパーティクルを含むガスの多くを掻き取り（図４（ｂ））、効果的にダクト３０内へ連れ込む。さらに、ダクト端部については、そこから吸引されるガスによるパージ効果で、パーティクルの付着が抑制される。
【００３９】
なお、前記吸引ガスは前記隙間ａの近傍領域で渦Ｗを発生させる可能性があるが、この渦Ｗは基板１４の上面及びプラズマ２２の発生領域から十分離れており、成膜に悪影響を及ぼすおそれはない。
【００４０】
▲５▼ ダクト３０の側壁３３と電極１８の両側面との隙間ｂや、ダクト３０の側壁３３の下面と基板搬送台１２の上面との隙間ｃを十分小さくして流路抵抗を大きくしているので、これらの隙間ｂ，ｃから無駄な（パーティクル除去に不要な）ガス吸引が行われるのを抑制してパーティクル除去効果を高めることができる。
【００４１】
２）第２の実施の形態（図５（ａ）（ｂ））
この実施の形態では、ダクト３０の幅寸法を電極１８の幅寸法（軸方向寸法）と略同一としている。すなわち、電極１８の両側面は完全に側方へ開放された状態とするとともに、ダクト３０の左右両側壁３３の前端面３３ｂを電極外周面に沿う円弧状とし、当該前端面３３ｂと電極外周面とを微小隙間ｅをおいて対向させている。しかし、前記第１の実施の形態と同様、水平壁３１の前端には切欠３４が形成され、この切欠３４における水平壁３１の端面と電極１８の外周面との隙間ａの寸法は大きく確保されている。
【００４２】
この構成においても、側壁３３の前端面３３ｂと電極１８の外周面との隙間ｅは小さく抑える（具体的には両隙間ｅにおけるガス流路抵抗の合成抵抗が、隙間ａにおけるガス流路抵抗や、隙間ｄ及び最狭隙間部δにおけるガス流路抵抗よりも大きくなるようにする）ことにより高い吸引効率を保ちながら、ダクト吸引口下端部や隙間ａにおいて有効なパーティクル除去ができる。この実施の形態は、電極１８の幅が成膜幅よりも大きい場合（すなわち電極１８の軸方向全域で成膜をする必要がない場合）に有効である。
【００４３】
３）第３の実施の形態（図６（ａ）（ｂ））
この実施の形態は、基板搬送台１２の幅と電極１８の幅とがほぼ等しい場合に有効なものである。ダクト３０の形状は、その両側壁３３が電極１８の両側面だけでなく、基板搬送台１２の両側面も側方から覆うように設定されている。すなわち、両側壁３３と基板搬送台１２の両側面とが対向した状態となっている。
【００４４】
この実施の形態においても、側壁３３と電極両側面との隙間ｂや、側壁３３と基板搬送台１２の両側面との隙間ｃ′を十分小さく設定する（隙間ｂの流路抵抗や隙間ｃ′における流路抵抗が、隙間ａにおけるガス流路抵抗や、隙間ｄ及び最狭隙間部δにおけるガス流路抵抗よりも大きくなるようにする）ことにより、パーティクル吸引除去効果を高めることができる。
【００４５】
４）第４の実施の形態（図７）
この実施の形態では、切欠３４に臨む水平壁３１の端面を下方に向かうに従って電極側に迫るナイフエッジ状端面３１ａとし、ダクト外部のガスをダクト内に誘い込みやすくしている。このような形状にすれば、前記隙間ａの最小寸法を小さくしながら、ガス流路抵抗を低く抑えることが可能である。
【００４６】
なお、本発明において、吸引口以外のダクトの形状は、適宜設定が可能である。例えば、前記傾斜壁３２を省略して天壁をすべて水平壁３１にしてもよいし、逆に天壁全体を傾斜させるようにしてもよい。また、図例のように底壁を省略するのではなく、従来のようにダクト底壁を設ける（すなわちダクトのみでガス吸引通路を形成する）ようにしても、従来の先細ダクトに比べてパーティクル除去効果を高めることが可能である。
【００４７】
【実施例】
薄膜材料としてアモルファスシリコンを選び、以下の成膜実験を行った。
【００４８】
▲１▼ 装置条件
実験には、アルミ合金製のドラム電極（図１の電極１８）、高速回転モータ、基板搬送台（図１の基板搬送台１２）、インピーダンスマッチング装置などを備えた装置を用い、ドラム電極は、その振動を防ぐため、マグネットカップリング及び磁気流体シールを介して前記高速モータに連結した。高周波電源には150MHzのものを用い、インピーダンス間マッチングユニットを介して電極部に高周波電力を印加し、最狭隙間部δにプラズマを発生させるようにした。電極１８の寸法は、直径300mm、幅100mmとし、最高回転速度を5000rpm（周速度79m/s)に設定した。ダクトには前記図１に示したダクト３０を用い、隙間ａの寸法を2mm、隙間ｂの寸法を0.5mm、隙間ｃの寸法を0.5mmとした。チャンバ１０には、排気速度1m³/minのドライポンプを接続し、その吸引力をダクト３０内におけるガスの吸引に兼用した。
【００４９】
▲２▼ 実施条件
洗浄を終えて乾燥させたガラス基板を試料台にセットし、成膜ギャップ（最狭隙間部δ）を設定した後、真空排気を行った。その後、ヘリウム（希釈ガス）と、水素及びシランの混合ガス（反応ガス）とをマスフローコントローラを通じてチャンバ内に導入し、雰囲気圧力を大気圧とした。この状態で電極を加熱し、さらに電極を回転させながらプラズマを発生させ、基板上にアモルファスシリコンの薄膜を形成した。成膜条件は、水素濃度を０〜10％、シラン濃度を0.01〜10％、雰囲気圧力を１気圧、成膜時間を30秒とした。その結果、投入電力が300〜2500Ｗ、電極回転数が1000〜5000rpmという広い範囲で、パーティクルを発生させることなく均一の薄膜を得ることができ、かつ、その得られた薄膜がまさしくアモルファスシリコンであることがラマン分光分析により確認された。その後も実験を５バッチ継続したが、チャンバ内にパーティクルの発生は見られなかった。
【００５０】
ダクト内壁面には、目視でかろうじて確認できる程度のうっすらとしたパーティクルの付着が部分的に存在したが、従来の先細ダクトと比べるとその付着量は飛躍的に減少した。
【００５１】
【発明の効果】
以上のように本発明は、電極の回転方向下流側に微粒子を吸引除去するためのダクトを設置するとともに、このダクトの吸引口形状を、前記電極の外周面のうち、前記基板と最狭隙間部を形成する最狭隙間形成部分の近傍位置から、当該最狭隙間形成部分よりも４５°以上１３５°以下だけ電極回転方向下流側の位置までの領域を覆う形状としたものであるので、当該ダクトのパーティクル除去性能を高めることにより、基板上にパーティクルが堆積するのを有効に抑止して高品質膜を高速で形成することができる効果がある。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態にかかる薄膜形成装置の要部を示す断面斜視図である。
【図２】前記薄膜形成装置の要部を示す断面側面図である。
【図３】前記薄膜形成装置に用いられるダクトの斜視図である。
【図４】（ａ）は前記薄膜形成装置におけるダクト内のガス流れを示す断面図、（ｂ）は同ダクトの上端と電極外周面との隙間におけるガス流れを示す断面図である。
【図５】（ａ）は本発明の第２の実施の形態にかかる薄膜形成装置の要部を示す断面斜視図、（ｂ）は同装置に用いられるダクトの斜視図である。
【図６】（ａ）は本発明の第３の実施の形態にかかる薄膜形成装置の要部を示す断面斜視図、（ｂ）は同装置に用いられるダクトの斜視図である。
【図７】本発明の第４の実施の形態にかかるダクトの斜視図である。
【図８】従来の薄膜形成装置を示す概略構成図である。
【図９】図８に示す薄膜形成装置における回転電極と基板との間での薄膜形成のメカニズムを示す図である。
【図１０】（ａ）は従来の薄膜形成装置におけるダクトの配置を示す断面正面図、（ｂ）は同ダクトの斜視図である。
【図１１】図１０に示す薄膜形成装置におけるガスの流れを示す断面図である。
【符号の説明】
１０チャンバ
１２基板搬送台
１４基板
１６電極
２４，２４ａ，２４ｂ，２４ｃパーティクル（微粒子）
３０ダクト
３１水平壁
３３側壁
３３ｂ側壁前端面
３４切欠
ａダクト吸引口上端と電極外周面との隙間
ｂ電極側面とダクトとの隙間
ｃダクト両側壁下端面と基板搬送台上面との隙間
ｃ′ ダクト両側壁と基板搬送台側面との隙間
ｅダクト両側壁前端面と電極外周面との隙間[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin film forming apparatus for forming a thin film made of amorphous silicon or the like on a substrate using a chemical reaction by plasma.
[0002]
[Prior art]
In recent years, as a plasma type thin film forming apparatus as described above, an apparatus in which a high-speed rotating electrode is opposed to a substrate has been developed (for example, see JP-A-9-104985). An outline of the apparatus is shown in FIGS.
[0003]
In FIG. 8, a substrate transfer table 12 is installed in a sealed chamber 10, and a substrate 14 is placed thereon, and the substrate transfer table 12 and the substrate 14 are connected to ground. An electrode 18 is disposed so as to face the substrate 14 with a slight gap. The electrode 18 has a substantially cylindrical shape extending in the depth direction in the figure, and a rotation shaft 16 passes through the center of the electrode 18. Both ends of the rotation shaft 16 are rotatably supported by support columns (not shown). The end of the rotating shaft 16 is electrically connected to a high frequency electrode terminal 19 on the outer surface of the chamber, and this high frequency electrode terminal 19 is connected to a high frequency power supply (not shown).
[0004]
In this apparatus, the inside of the chamber 10 is evacuated, and a high frequency power or a direct current power is applied to the electrode 18 while rotating the electrode 18 to generate a plasma 22 between the electrode 18 and the substrate 14 and a reaction gas (not shown). When a reaction gas (mixed gas of SiH ₄ and H _{2 in the} illustrated example) and a dilution gas (for example, He) are introduced from the supply source into the chamber 10, these gases are caused to rotate between the electrode 18 and the substrate 14 by the rotation of the electrode 18. The reaction gas is caused to undergo a chemical reaction. As a result of scanning the substrate 14 in a predetermined direction (direction orthogonal to the rotation axis direction of the electrode 18) together with the substrate carrier 12 while causing such a chemical reaction, a thin film (FIG. 9) is formed on the substrate 14 as shown in FIG. In this example, a thin film 23 made of amorphous silicon is formed.
[0005]
This apparatus makes it possible to continuously form a uniform thin film 23 in a large area at a high speed and to generate glow discharge plasma under a pressure of 1 atm or more, which has been difficult in the past. As shown in FIG. 9, when film formation is performed under high pressure and at high speed, the decomposition reaction of the reaction gas occurs rapidly in the gas phase. Silicon atoms that have not contributed to the film 23 are bonded to each other to form particles (fine particles) 24. When such particles 24 are deposited on the substrate 14, the surface form of the film 23 is disturbed and becomes a factor that hinders the formation of a high quality film.
[0006]
Therefore, the publication discloses a duct 90 as shown in FIGS. 10 (a) and 10 (b) arranged on the downstream side in the electrode rotation direction, and the particles 24 are sucked and removed through this duct 90. Yes. The duct 90 has a suction port 92 at the tip thereof formed in a tapered shape that is narrower than other portions. The suction port 92 is formed on the downstream side in the rotation direction of the electrode 18 with the outer peripheral surface of the electrode 18 and the upper surface of the substrate 14. Is inserted in the gap. The gas suction speed at the suction port 92 is equal to or higher than the peripheral speed of the electrode surface, preferably twice or more, more preferably 10 times or more the peripheral speed of the electrode surface.
[0007]
[Problems to be solved by the invention]
FIG. 11 shows a gas flow state in the vicinity of the duct 90. As shown in this figure, the following disadvantages exist in the conventional duct structure and arrangement.
[0008]
A gap always exists between the upper surface of the duct 90 and the outer peripheral surface of the electrode 18, and between the lower surface of the duct 90 and the upper surface of the substrate 14, so that gas is sucked into the duct suction port 92 through this gap. Accordingly, the gas suction speed in the vicinity of the electrode 18 decreases. Therefore, even if the suction port 92 is brought close to the electrode 18 and the suction speed at the suction port 92 is increased, there is a limit in increasing the gas suction speed in the vicinity of the electrode, and effective removal of particles in the vicinity of the electrode is required. Is difficult to do.
[0009]
The particles are not necessarily small enough to be entrained in the air flow, but also large particles (particles 24b shown in FIG. 11) that scatter in the circumferential tangential direction of the electrode 18 due to inertial force. Exists. Further, the particles 24 are not necessarily transported from the gas phase to the downstream side (duct 90 side), but once adhered to the surface of the electrode 18, the particles 24 are separated and re-scattered at a position far away from the substrate 14. Sometimes. These particles cannot be collected effectively by the tapered duct 90.
[0010]
Since the gas containing the particles 24 collides with the duct suction port 92 from the front, particles are likely to be deposited in the vicinity thereof (particles 24c shown in FIG. 11), and the duct itself in which such particles 24c are deposited becomes a contamination source. There is a fear.
[0011]
The gas flow in the circumferential direction of the electrode dragged by the high-speed rotating electrode 18 intersects with the gas flow sucked from the gap between the electrode 18 and the duct 90, thereby distant from the generation region of the plasma 22. The vortex W will be formed at the position where there is not. This vortex W causes active reaction intermediates or clusters thereof to stay for a long time and is a factor for promoting particle growth.
[0012]
A flow stagnation region 94 is formed in the vicinity of the substrate 14 due to the flow of gas sucked from the gap between the upper surface of the substrate 14 and the duct 90. This stagnation region 94, like the vortex W, causes active reaction intermediates or clusters thereof to stay for a long time, and is a factor that promotes particle growth.
[0013]
In view of such circumstances, the present invention provides a thin film forming apparatus that enables high-speed formation of a high-quality film by effectively suppressing the accumulation of particles on a substrate by enhancing the particle removal performance of the duct. The purpose is to do.
[0014]
[Means for Solving the Problems]
As means for solving the above-mentioned problems, the present invention provides the substrate by causing a chemical reaction by supplying a reactive gas to the plasma while generating a plasma between the rotating electrodes facing the substrate. In the thin film forming apparatus for forming a thin film thereon, a duct for sucking and removing fine particles is installed on the downstream side in the rotation direction of the electrode, and the suction port shape of the duct is formed on the substrate of the outer peripheral surface of the electrode. And a shape that covers a region from a position near the narrowest gap forming portion that forms the narrowest gap portion to a position downstream from the narrowest gap forming portion by 45 ° to 135 ° with respect to the electrode rotation direction. is there.
[0015]
According to this configuration, instead of inserting a tapered duct between the outer peripheral surface of the electrode and the substrate as in the prior art, the duct is arranged so that the duct suction port is widened and the suction port covers a predetermined portion of the electrode. Therefore, from the small-diameter particles (fine particles) accompanying the airflow to the large-diameter particles scattered in the tangential direction of the rotating electrode due to the inertial force, it can be effectively collected by the duct.
[0016]
Here, the region where the outer peripheral surface of the electrode is covered by the duct is 45 ° to 135 ° from the narrowest gap forming portion from the position near the narrowest gap forming portion that forms the narrowest gap portion with the substrate. The area up to the position downstream of the electrode rotation direction is less than 45 °, so that the cover area of the electrode by the duct is too small, and the difference between the conventional tapered duct and the particle suction effect is small. If exceeded, the duct cross-sectional area becomes too large and the gas flow in the duct becomes unstable and unsteady circulation flow tends to occur. This is because there is a risk of accumulation.
[0017]
In the present invention, there is a possibility that particles collide with the inner wall of the duct, but such particles are limited to relatively large ones, and the adhesion force to the wall surface is weak. Moreover, since the particle collision flux (the number of fine particles flying to the duct inner wall per unit time and unit area) is significantly smaller than the conventional tapered duct, the degree of particle adhesion to the duct inner wall is extremely low and it takes. There is no risk of the inner wall becoming a source of contamination.
[0018]
In this apparatus, the gas flow path resistance of the gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode and the flow resistance of the gas sucked from the lower end of the suction port of the duct are substantially equal. It is more preferable to arrange the duct in With this configuration, gas is sucked in a good balance from both the upper and lower ends of the suction port of the duct. Among these, the gas (relatively clean gas) sucked into the duct through the gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode is opposed to the gas dragged by the high-speed rotating electrode. Yes, it scrapes most of the gas containing particles near the electrode surface and effectively guides it into the duct. Thereby, the particle removal action is enhanced. Furthermore, at the duct end, the adhesion of particles is suppressed by the purge effect of the gas sucked from the duct end.
[0019]
The gas sucked into the duct through the gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode is circulated inside the duct (vortex) by facing the gas dragged by the high-speed rotating electrode. However, since this vortex is sufficiently separated from the plasma generation region and the substrate surface, there is no possibility of adversely affecting the thin film on the substrate.
[0020]
In the present invention, the specific shape of the duct can be variously set. For example, the duct may have a shape that covers a part of both side surfaces of the electrode from the side, or the duct may have a shape in which the left and right side walls oppose the electrode along the outer peripheral surface of the electrode. . In the former case, the gas flow path resistance of the gap formed between the both side surfaces of the electrode and the duct is the flow resistance of gas sucked from the lower end of the suction port of the duct, and the upper end of the suction port of the duct. By reducing the gap formed between both sides of the electrode and the duct so as to be larger than the gas flow path resistance of the gap formed between the electrode and the outer peripheral surface of the electrode, it does not contribute to particle removal. Gas suction can be suppressed, and the particle suction effect by the duct can be further enhanced. Also in the latter case, the gas flow path resistance of the gap formed between the end surfaces of the left and right side walls of the duct and the electrode outer peripheral surface is the flow resistance of the gas sucked from the lower end of the suction port of the duct, By reducing the gap formed between the both side walls of the duct and the electrode outer peripheral surface so as to be larger than the gas flow path resistance of the gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode, The suction of useless gas that does not contribute to particle removal can be suppressed, and the particle suction effect by the duct can be further enhanced.
[0021]
According to the present invention, the duct is configured to open toward the substrate upper surface or the substrate placement surface, and the gas suction passage is formed by the substrate upper surface or the substrate placement surface and the duct. 11, it is possible to completely prevent the stagnation region 94 and the vortex W of the flow as shown in FIG. 11 from occurring in the vicinity of the substrate, and the particle removal effect can be further enhanced.
[0022]
Specifically, the lower end surface of the side wall of the duct may be opposed to the upper surface of the substrate or the substrate mounting surface, or the side wall of the duct and the side surface of the substrate transfer table are opposed to each other (that is, the side wall of the duct is It may be arranged so as to cover the side of the substrate carrier. In either case, the gas flow path resistance of the gap formed by the lower end surface of the both side walls of the duct and the upper surface of the substrate or the substrate mounting surface, and the gas flow of the gap formed by the side walls of the duct and the side surface of the substrate transfer table The path resistance is made larger than the flow resistance of the gas sucked from the lower end of the suction port of the duct and the gas flow path resistance of the gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode. Thus, it is possible to suppress the suction of useless gas that does not contribute to particle removal, and it is possible to further enhance the particle suction effect by the duct.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Since the basic principle and basic configuration of the thin film forming apparatus shown in these embodiments are the same as those shown in FIGS. 8 and 9, the constituent elements equivalent to those shown in FIGS. The same reference numerals are given and description thereof is omitted. However, the thin film material formed in the present invention is not limited to the amorphous silicon described above, and can be widely applied to materials that can form a thin film by a chemical reaction using plasma, such as C, SiC, and SiO 2.
[0024]
1) First embodiment (FIG. 1)
This embodiment is suitable when the width of the substrate carrier 12 is larger than the width of the electrode 18 (axial dimension) and the width of the substrate 14.
[0025]
The illustrated duct 30 has a top wall composed of a horizontal wall 31 and an inclined wall 32, and a pair of side walls 33 extending downward from the left and right sides of the top wall, and has a shape that opens downward. The inclined wall 32 is inclined in a direction that decreases as the distance from the horizontal wall 31 increases. The lower end surfaces of the both side walls 33 are horizontal, and are opposed to each other with a small gap c between the upper surface (substrate mounting surface) of the substrate transport table 12 and the duct 30 is arranged so as to be parallel thereto. . That is, a gas suction passage is formed by the duct 30 and the upper surface of the substrate transport table 12, and the opening 35 on the opposite side to the electrode 18 is an exhaust port, to which a pump (not shown) is connected. Further, the substrate 14 passes through the inside of the side walls 33.
[0026]
When the width of the substrate 14 is as large as the width of the substrate transfer table 12, a minute gap c is secured between the upper surface of the substrate 14 and the side wall 33, and the gas suction passage is formed between the upper surface of the substrate 14 and the duct 30. May be formed.
[0027]
A rectangular notch 34 is formed at the front end of the horizontal wall 31, and the duct 30 is disposed in such a positional relationship that the electrode 18 enters the notch 34. Accordingly, both side surfaces of the electrode 18 in the axial direction are partially covered by the duct 30 from the side. However, arc-shaped notches 33 a for avoiding interference with the electrode rotation shaft 16 are formed at the front end portions of the side walls 33.
[0028]
The area where the outer peripheral surface of the electrode 18 is covered by the suction port of the duct 30 is a position in the vicinity of the narrowest gap δ between the electrode 18 and the substrate 14 (in the example of FIG. 2, the electrode rotation direction is slightly more than the narrowest gap δ). A position on the downstream side; this position may be a position slightly upstream of the narrowest gap δ in the direction of electrode rotation), and a predetermined angle α (about 90 ° in the figure) from the narrowest gap δ. Only the region up to the downstream position is set. A suitable range of the angle α will be described later.
[0029]
Moreover, each gap | interval dimension in this apparatus is set as follows.
[0030]
A gap a between the end face (the upper end of the duct suction port) of the horizontal wall 31 and the outer peripheral surface of the electrode 18 in the notch 34... The gas flow path resistance in the gap a is the flow resistance of the gas sucked from the lower end of the duct suction port. The dimension of the gap a and the thickness dimension of the horizontal wall 31 are set so as to be substantially equal. Here, “the flow resistance of the gas sucked from the lower end of the duct suction port” means the narrowest gap δ between the upper surface of the substrate 14 and the electrode 18 and the outer peripheral surface of the electrode 18 in the case of the structure shown in FIG. And the resistance of the gas suction channel in the electrode width direction formed by the gap d surrounded by the end face of the side wall 33, and the resistance of the gas suction channel in the electrode circumferential direction formed by the narrowest gap portion δ. It means the combined flow resistance. If the front end of the duct 30 is located upstream of the narrowest gap portion δ in the electrode rotation direction and there is no flow path due to the gap d, the circumferential direction of the electrode formed by the narrowest gap portion δ This means the flow resistance itself of the flow path.
[0031]
The gap b between the both side surfaces of the electrode 18 and the end face of the horizontal wall 31... The combined resistance of the gas flow path resistance in these gaps b is sucked from the gas flow path resistance in the gap a or the lower end of the duct suction port. The gap b is reduced to the extent that it becomes larger than the gas flow resistance.
[0032]
The gap c between the lower end surface of the side wall 33 and the upper surface of the substrate transfer table 12... The combined resistance of the gas flow path resistance in these gaps c is sucked from the gas flow path resistance in the gap a or the lower end of the duct suction port. The gap c is reduced to the extent that it becomes larger than the gas flow resistance.
[0033]
In this apparatus, by sucking the gas in the duct 30 from the exhaust port 35, the following effects can be obtained.
[0034]
(1) Since the suction port of the duct 30 covers the outer peripheral surface of the electrode 18 over a relatively wide range (about 1/4 in the example shown in the figure), as shown in FIGS. Can be effectively collected from the small-diameter particles 24a that accompany to the large-diameter particles 24b that scatter in the tangential direction of the rotating electrode due to the inertial force.
[0035]
Here, the angle α shown in FIG. 2 (the central angle of the electrode 18 corresponding to the region from the position where the narrowest gap δ is formed to the horizontal wall 31) is 45 ° or more and less than 135 °, more preferably. Is preferably set to approximately 90 °. If the angle α is less than 45 °, the cover area of the electrode 18 by the duct 30 is too small, and the difference in the particle suction effect is smaller than that of the conventional tapered duct. Conversely, if the angle α exceeds 135 °, the flow of the duct 30 The road cross-sectional area becomes too large, the gas flow in the duct becomes unstable and an unsteady circulation flow is likely to occur, and there is a possibility that particles accumulate on the surface of the electrode 18 particularly under conditions where the electrode rotation speed is high. Because there is.
[0036]
(2) The number of particles that collide with the inner wall of the duct (particle collision flux with respect to the inner wall of the duct) is very small compared to the conventional tapered duct, and the particles that collide with the inner wall have a relatively large diameter (the illustrated particle Since the adhesion force to the inner wall of the duct is small, the amount of particles adhering to the inner wall of the duct is very small, and this does not become a contamination source.
[0037]
(3) The bottom wall of the duct 30 is omitted so that the entire duct opens downward, and the upper surface of the substrate 14 and the upper surface (substrate mounting surface) of the substrate transfer table 12 are also used as the gas suction passage forming member. Therefore, unlike the conventional duct having the bottom wall, the flow stagnation region 94 and the vortex (circulation flow) W as shown in FIG. Particle accumulation on the substrate due to the stagnation region 94 and the vortex W can be prevented.
[0038]
(4) A relatively clean gas flows from the outside to the inside of the duct 30 through the gap a between the end surface of the horizontal wall 31 and the outer peripheral surface of the electrode 18. This gas is in a direction opposite to the gas flow that moves while being dragged by the rotation of the rotating electrode 18, scraping off most of the gas containing particles in the vicinity of the electrode surface (FIG. 4B) and effectively ducting. Take it into 30. Furthermore, at the duct end, the adhesion of particles is suppressed by the purge effect of the gas sucked from the duct end.
[0039]
The suction gas may generate a vortex W in the vicinity of the gap a. However, the vortex W is sufficiently away from the upper surface of the substrate 14 and the generation region of the plasma 22 and adversely affects film formation. There is no fear.
[0040]
(5) The flow path resistance is increased by sufficiently reducing the gap b between the side wall 33 of the duct 30 and both side surfaces of the electrode 18 and the gap c between the lower surface of the side wall 33 of the duct 30 and the upper surface of the substrate carrier 12. Therefore, it is possible to suppress the unnecessary gas suction (unnecessary for particle removal) from these gaps b and c and enhance the particle removal effect.
[0041]
2) Second embodiment (FIGS. 5A and 5B)
In this embodiment, the width dimension of the duct 30 is substantially the same as the width dimension (axial dimension) of the electrode 18. That is, the both side surfaces of the electrode 18 are completely opened to the side, and the front end surfaces 33b of the left and right side walls 33 of the duct 30 are formed in an arc shape along the electrode outer peripheral surface, and the front end surface 33b and the electrode outer peripheral surface are formed. Are opposed to each other with a minute gap e. However, as in the first embodiment, a notch 34 is formed at the front end of the horizontal wall 31, and the dimension of the gap a between the end surface of the horizontal wall 31 and the outer peripheral surface of the electrode 18 in the notch 34 is ensured to be large. ing.
[0042]
Even in this configuration, the gap e between the front end surface 33b of the side wall 33 and the outer peripheral surface of the electrode 18 is kept small (specifically, the combined resistance of the gas flow path resistance in both the gaps e By making the gap d and the gas flow path resistance larger than the narrowest gap portion δ), it is possible to effectively remove particles at the lower end of the duct suction port and the gap a while maintaining high suction efficiency. This embodiment is effective when the width of the electrode 18 is larger than the film forming width (that is, when it is not necessary to form the film in the entire axial direction of the electrode 18).
[0043]
3) Third embodiment (FIGS. 6A and 6B)
This embodiment is effective when the width of the substrate carrier 12 and the width of the electrode 18 are substantially equal. The shape of the duct 30 is set so that both side walls 33 cover not only both side surfaces of the electrode 18 but also both side surfaces of the substrate transport table 12 from the side. That is, both side walls 33 and both side surfaces of the substrate transport table 12 face each other.
[0044]
Also in this embodiment, the gap b between the side wall 33 and both sides of the electrode and the gap c ′ between the side wall 33 and both sides of the substrate transport table 12 are set sufficiently small (the flow path resistance of the gap b and the gap c ′. In this case, the effect of sucking and removing particles can be enhanced by making the flow path resistance in the gas flow path resistance in the gap a greater than the gas flow path resistance in the gap a and the gas flow path resistance in the gap d and the narrowest gap portion δ.
[0045]
4) Fourth embodiment (FIG. 7)
In this embodiment, the end face of the horizontal wall 31 facing the notch 34 is a knife-edge end face 31a that approaches the electrode side as it goes downward, so that the gas outside the duct can be easily drawn into the duct. With such a shape, it is possible to keep the gas flow path resistance low while reducing the minimum dimension of the gap a.
[0046]
In the present invention, the shape of the duct other than the suction port can be set as appropriate. For example, the inclined wall 32 may be omitted, and the top wall may be all the horizontal wall 31, or conversely, the entire top wall may be inclined. In addition, instead of omitting the bottom wall as shown in the figure, the duct bottom wall is provided as in the conventional case (that is, the gas suction passage is formed only by the duct). It is possible to enhance the removal effect.
[0047]
【Example】
Amorphous silicon was selected as the thin film material, and the following film formation experiment was conducted.
[0048]
(1) In the apparatus condition experiment, an apparatus equipped with an aluminum alloy drum electrode (electrode 18 in FIG. 1), a high-speed rotation motor, a substrate transfer table (substrate transfer table 12 in FIG. 1), an impedance matching device, and the like is used. The drum electrode was connected to the high-speed motor through a magnet coupling and a magnetic fluid seal in order to prevent vibration. A high-frequency power source of 150 MHz was used, and high-frequency power was applied to the electrode part via the impedance matching unit to generate plasma in the narrowest gap part δ. The dimensions of the electrode 18 were 300 mm in diameter and 100 mm in width, and the maximum rotation speed was set to 5000 rpm (circumferential speed 79 m / s). The duct 30 shown in FIG. 1 is used as the duct, and the dimension of the gap a is 2 mm, the dimension of the gap b is 0.5 mm, and the dimension of the gap c is 0.5 mm. A dry pump with an exhaust speed of 1 m ³ / min was connected to the chamber 10, and the suction force was also used for gas suction in the duct 30.
[0049]
{Circle around (2)} Execution Conditions The glass substrate that had been cleaned and dried was set on a sample stage, a film formation gap (narrowest gap δ) was set, and then evacuation was performed. Thereafter, helium (diluted gas) and a mixed gas of hydrogen and silane (reactive gas) were introduced into the chamber through a mass flow controller, and the atmospheric pressure was set to atmospheric pressure. In this state, the electrode was heated, and plasma was generated while rotating the electrode to form an amorphous silicon thin film on the substrate. The film formation conditions were a hydrogen concentration of 0 to 10%, a silane concentration of 0.01 to 10%, an atmospheric pressure of 1 atm, and a film formation time of 30 seconds. As a result, a uniform thin film can be obtained without generating particles in a wide range of input power of 300 to 2500 W and electrode rotation speed of 1000 to 5000 rpm, and the obtained thin film is exactly amorphous silicon. This was confirmed by Raman spectroscopy. Thereafter, the experiment was continued for 5 batches, but no generation of particles was observed in the chamber.
[0050]
On the inner wall surface of the duct, there was a slight amount of particle adhesion that was barely visible, but the amount of adhesion was dramatically reduced compared to conventional tapered ducts.
[0051]
【The invention's effect】
As described above, the present invention installs a duct for sucking and removing fine particles on the downstream side in the rotation direction of the electrode, and the suction port shape of this duct is the narrowest gap between the substrate and the substrate on the outer peripheral surface of the electrode. Since it is a shape that covers a region from the position near the narrowest gap forming portion that forms the part to the position downstream of the narrowest gap forming portion by 45 ° or more and 135 ° or less in the electrode rotation direction. By improving the particle removal performance of the duct, it is possible to effectively suppress the accumulation of particles on the substrate and to form a high quality film at high speed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional perspective view showing a main part of a thin film forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a sectional side view showing a main part of the thin film forming apparatus.
FIG. 3 is a perspective view of a duct used in the thin film forming apparatus.
4A is a cross-sectional view showing the gas flow in the duct in the thin film forming apparatus, and FIG. 4B is a cross-sectional view showing the gas flow in the gap between the upper end of the duct and the outer peripheral surface of the electrode.
5A is a cross-sectional perspective view showing a main part of a thin film forming apparatus according to a second embodiment of the present invention, and FIG. 5B is a perspective view of a duct used in the apparatus.
6A is a cross-sectional perspective view showing a main part of a thin film forming apparatus according to a third embodiment of the present invention, and FIG. 6B is a perspective view of a duct used in the apparatus.
FIG. 7 is a perspective view of a duct according to a fourth embodiment of the present invention.
FIG. 8 is a schematic configuration diagram showing a conventional thin film forming apparatus.
9 is a view showing a mechanism of thin film formation between a rotating electrode and a substrate in the thin film forming apparatus shown in FIG.
10A is a cross-sectional front view showing the arrangement of ducts in a conventional thin film forming apparatus, and FIG. 10B is a perspective view of the ducts.
11 is a cross-sectional view showing a gas flow in the thin film forming apparatus shown in FIG.
[Explanation of symbols]
10 Chamber 12 Substrate transfer table 14 Substrate 16 Electrodes 24, 24a, 24b, 24c Particles (fine particles)
30 Duct 31 Horizontal wall 33 Side wall 33b Side wall front end face 34 Notch a Clearance between the upper end of the duct suction port and the outer peripheral surface of the electrode b Clearance between the side face of the electrode and the duct c Clearance between the lower end face of both side walls of the duct and the upper surface of the substrate carrier c 'Duct Gap between both side walls and substrate transfer table side e Gap between front end face of both side walls of duct and outer peripheral surface of electrode

Claims

In the thin film forming apparatus for forming a thin film on the substrate by supplying a reactive gas to the plasma and causing a chemical reaction while generating a plasma between the rotating electrode and the substrate, A duct for sucking and removing fine particles is installed on the downstream side in the rotation direction, and the suction port shape of this duct is the narrowest gap forming portion that forms the narrowest gap portion with the substrate on the outer peripheral surface of the electrode. A thin film forming apparatus characterized by having a shape that covers a region from a nearby position to a position downstream of the narrowest gap forming portion by 45 ° or more and 135 ° or less in the electrode rotation direction.

2. The thin film forming apparatus according to claim 1, wherein a gas flow path resistance of a gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode, and a flow resistance of gas sucked from the lower end of the suction port of the duct A thin film forming apparatus characterized in that ducts are arranged so as to be substantially equal to each other.

3. The thin film forming apparatus according to claim 1, wherein the duct is shaped to cover a part of both side surfaces of the electrode from the side, and gas in a gap formed between the both side surfaces of the electrode and the duct. Formation of a thin film characterized in that a gap formed between both sides of the electrode and the duct is reduced so that a flow resistance is larger than a flow resistance of gas sucked from the lower end of the suction port of the duct apparatus.

4. The thin film forming apparatus according to claim 3, wherein a gas flow path resistance of a gap formed between both sides of the electrode and the duct is a gap formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode. A thin film forming apparatus characterized in that a gap formed between both side surfaces of the electrode and a duct is reduced so as to be larger than a gas flow path resistance.

3. The thin film forming apparatus according to claim 1, wherein the duct has a shape in which both left and right side walls oppose the electrode along the outer peripheral surface of the electrode, and between the outer peripheral surface of the electrode and the end surfaces of the both side walls of the duct. A gap formed between the outer peripheral surface of the electrode and both side walls of the duct so that the gas flow path resistance of the gap formed therebetween is greater than the flow resistance of the gas sucked from the lower end of the suction port of the duct. A thin film forming apparatus characterized by being made small.

6. The thin film forming apparatus according to claim 5, wherein a gas flow path resistance of a gap formed between the outer peripheral surface of the electrode and the end surfaces of both side walls of the duct is formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode. A thin film forming apparatus characterized in that a gap formed between the outer peripheral surface of the electrode and both side walls of the duct is reduced so as to be larger than a gas flow path resistance of the formed gap.

7. The thin film forming apparatus according to claim 1, wherein the duct has a shape opening toward a substrate upper surface or a substrate mounting surface, and a gas suction passage is formed between the substrate upper surface or the substrate mounting surface and the duct. A thin film forming apparatus characterized in that is formed.

8. A thin film forming apparatus according to claim 7, wherein the lower end surface of the side wall of the duct and the upper surface of the substrate or the substrate mounting surface are opposed to each other, and the gas flow path resistance of a gap formed between them is lower end of the suction port of the duct. A thin film forming apparatus characterized in that a gap formed between the lower end surface of both side walls of the duct and the upper surface of the substrate or the substrate mounting surface is made smaller than the flow resistance of the gas sucked from the portion.

9. The thin film forming apparatus according to claim 8, wherein a gas flow path resistance of a gap formed between the lower end surface of the side wall of the duct and the upper surface of the substrate or the substrate mounting surface is formed between the upper end of the suction port of the duct and the outer peripheral surface of the electrode. Thin film formation characterized in that the gap formed between the lower end surface of both side walls of the duct and the upper surface of the substrate or the substrate mounting surface is made smaller than the gas flow path resistance of the gap formed therebetween apparatus.

8. The thin film forming apparatus according to claim 7, wherein the side wall of the duct and the side surface of the substrate transport table are opposed to each other, and the gas flow path resistance of a gap formed therebetween is sucked from the lower end of the suction port of the duct. A thin film forming apparatus characterized in that a gap formed between both side walls of the duct and a side surface of the substrate transfer table is reduced so as to be larger than a gas flow resistance.

The thin film forming apparatus according to claim 10, wherein a gas flow path resistance of a gap formed between a side wall of the duct and a side surface of the substrate transfer table is formed between an upper end of the suction port of the duct and an outer peripheral surface of the electrode. A thin film forming apparatus characterized in that a gap formed between both side walls of a duct and a side surface of a substrate transfer table is reduced so as to be larger than a gas flow path resistance of the gap.