JP4212210B2 - Surface treatment equipment - Google Patents

Description

上述した試料１〜４の結晶性薄膜は、いずれもＸ線回折で（２２０）に配向する結晶性薄膜であることが確認された。
更に、これらの薄膜をｐ−ｉ−ｎ型の太陽電池に応用する場合には、ｎ型、ｉ型（上記条件）と積層した後、ｐ型を積層する前に上記条件よりも低パワー且つ低速で更に薄くｉ型の層を積層してからｐ型の層を成膜して電池とすることにより、太陽電池の効率が向上する。例えば、８０Ｐａ，１００〜４５０℃、Ｈ₂ ；４０ｓｃｃｍ、ＳｉＨ₄ ；１．５ｓｃｃｍ、ＲＦパワー；０．２５Ｗ／ｃｍ² の条件で且つ成膜速度を０．０１μｍ／ｍｉｎとして、厚さ５〜１００ｎｍのｉ層をバッファ層として挿入すると、太陽電池の効率が５０％向上した。
【０１０５】
このように成膜速度が向上した理由としては、先ず、プラズマ吹出口７におけるホローアノード放電、カソード電極１１の貫通孔１１ｂ及びその空洞内部でのホローカソード放電により高密度なプラズマが得られたことが挙げられる。更に、カソード電極１１のプラズマに接触する表面積を増大させたことにより、その自己バイアスをプラスの側にもっていくことができ、プラズマがアノード電極に近い領域でも発生するため、基板処理室４へのプラズマ吹出口７を通して効率良く基板表面へとプラズマを導くことができる。また、この自己バイアスの制御により、同時にプラズマ空間電位をも制御することが可能になったため、そのプラズマ空間電位を適度に設定し、成膜速度に応じた適度なイオンの衝撃を与えることができ、高速成膜での結晶化が可能となったものと考えられる。
【０１０６】
なお、上述の表面処理装置２１は、成膜以外のアッシングやエッチング、イオンドーピング等の他の表面処理を行った場合にも、従来よりも低温で且つ高速に表面処理を行うことが可能であった。
【０１０７】
図６は、第４実施例による表面処理装置２２の概略図である。同装置２２は、空洞体であるカソード電極１１に形成された貫通孔１１ｂの内壁面及びプラズマ吹出口７の内壁面に磁石１０が配されている点で上述した第３実施例と異なるが、その他の構成は上記第３実施例の表面処理装置２１と同一である。
【０１０８】
前記磁石１０の磁場は、磁力線の方向が上記貫通孔１１ｂ及びプラズマ吹出口７の各軸線方向と平行になるように印加されることが望ましい。同磁石の強度は前記貫通孔１１ｂ及びプラズマ吹出口７のそれぞれの軸中心において１〜２０００ｍＴ、内壁面及びその近傍で２〜２０００ｍＴとし、より好ましくは軸中心で５〜５００ｍＴ、内壁面及びその近傍で５〜１０００ｍＴとする。
【０１０９】
このように貫通孔１１ｂ及びプラズマ吹出口７に磁場を形成することにより、そこに発生しているプラズマ内の電子の軌道を前記磁場により調整し、前記貫通孔１１ｂ及びプラズマ吹出口７の内部に電子を長く留まらせることができる。この電子の軌道調整により、電子のエネルギー（電子温度）を高めることなく、原料ガスへの電子の作用時間を長くできるため、活性種の生成が促進され、成膜速度が向上する。
【０１１０】
また、磁石１０を配して磁場を形成することにより、貫通孔１１ｂの開口幅Ｗや長さＴ及びプラズマ吹出口７の開口幅Ｗの寸法の許容範囲が、磁石１０を配していない場合に比べて概ね３０％程度広がる。
【０１１１】
なお、本実施例では全ての貫通孔１１ｂ及びプラズマ吹出口７に磁石１０を配しているが、それら全てに磁石１０を配するのではなく、選択されたいずれかにのみ磁石１０を配することもできる。また、電磁石等の手段により磁場を形成することも可能である。更には、前記磁石１０は、例えば前記貫通孔１１ｂ及び前記プラズマ吹出口７の内壁面内に埋設することもできる。或いは図７（ａ）に示すように空洞体である前記カソード電極１１の上壁部１１ｃ内に埋設したり、図７（ｂ）に示すように、前記カソード電極１１の外側、上壁部１１ｃの上方に配することもできる。このような磁石１０の極性を含めた配置と磁場の強度とはプラズマ密度を高めるよう、任意に設定される。
【０１１２】
また、空洞内部のホローカソード放電がより高密度になるよう、前記空洞内部にも磁場を形成すべく磁石を配置することも可能である。この場合には、空洞内部における磁力線が電極面と平行になるように、磁場を付与することが望ましい。例えば、図８（ａ）に示すように、カソード電極１１の上下壁部１１ｃ，１１ａの内部や同カソード電極１１の周壁部の外側に配したり、図８（ｂ）に示すように、カソード電極１１の外側、上壁部１１ｃの上方や、同カソード電極の下壁部１１ａの内部、周壁部の外側などに配してもよい。また、図８（ｃ）に示すように周壁部の内部に埋設することもできる。なお、同図８（ｃ）は各種配置を一図にまとめて記載したものである。
【０１１３】
これらの図は磁石の配置の単なる例示にすぎず、これら図面に開示された磁石１０の配置位置や配置個数に限定されるものではない。前記磁石１０をカソード電極１１の内部に埋設又は外部に配置し、或いはその組み合わせにより、前記空洞内部や貫通孔１１ｂでのホローカソード放電がより高密度になるよう、磁石の配置と磁場強度とを任意に設定することができる。なお、これらの磁石１０の配置にあたっては、前記磁石１０がプラズマに直接晒されることがないよう取り付けることが好ましい。
【０１１４】
〈実験４〉
この図６に示す第４実施例による表面処理装置２２を用いて、上述の第３実施例の実験２と同一の条件、すなわち、モノシランガス（ＳｉＨ₄)を７ｃｍ³ ／ｍｉｎ．の流量で、また水素ガスを１０５ｃｍ³ ／ｍｉｎ．の流量で導入すると共に、成膜室の圧力を２９Ｐａ、基板温度を１５０〜２６０℃に調整して、１３．５６ＭＨｚ、０．１Ｗ／ｃｍ² の高周波電力を印加し、白板ガラスの基板に成膜処理を行った。その結果、成膜速度が７０Å／ｓｅｃ．と上述の第３実施例の場合と比べて更に７５％も高速での成膜が可能となり、このような高速成膜であって薄膜は微結晶化しており、太陽電池として十分に機能する薄膜であった。
【０１１５】
更に、カソード電極１１における貫通孔１１ｂ又はその空洞内部でのホローカソード放電により生じるプラズマ密度を大きくする変形例を図９に示す。
先ず、前記貫通孔１１ｂにおいてホローカソード放電を効率良く発生させる観点からは、前記貫通孔１１ｂの長さＴは大きいほうが有利であり、より強いプラズマを発生させることができる。しかしながら、前記カソード電極の下壁部１１ａの厚みは、材料コストの観点からも空洞内部に導入されるガス圧及び印加電力に耐え得る最小の厚みにすることが望ましい。
【０１１６】
そのため、前記貫通孔１１ｂの長さＴを長くするためには、同貫通孔１１ｂの周縁にノズル体１２を取り付けることが望ましい。なお、このノズル体１２は前記貫通孔１１ｂからプラズマ発生室３側へ突設してもよく、或いは空洞内部へ突設することもできる。更には両側へ突設してもよい。また、同ノズル体１２を図９に示すように磁石１０により構成することもできる。但し、磁石１０が直接プラズマに晒されることのないようにすることが好ましい。
【０１１７】
なお、図９に示すノズル体１２はいずれも、その中心線を貫通孔１１ｂの線と一致させて配しているが、前記ノズル体１２の中心線を前記貫通孔１１ｂの軸線に対して角度をもって配する、即ち、ノズル体１２を斜めに配することもできる。また、図９に示すノズル体１２は断面積が一定の筒体であるが、かかる形状に限定されるものではなく、その断面積を漸増又は漸減させる形状をもつ筒体であってもよい。更にはチューブ状のノズル体をらせん状に配することもできる。
かかるノズル体の変形については、上述したプラズマ吹出口や凹部に取り付けられるノズル体にも適用が可能である。
【０１１８】
更に、プラズマが接触するカソード電極１１の表面積を増大させるために、同カソード電極１１の空洞内部をその高さ方向に延在する隔壁１１ｅにより仕切ることもできる。このように表面積を自在に調節することができるため、同カソード電極１１の自己バイアスを自由に制御できる。なお、前記隔壁１１ｅはカソード電極１１の上下の壁部１１ｃ，１１ａと密着していなくてもよく、隙間が形成され仕切られた各空間が連通していてもよい。
【０１１９】
仕切られた各空間には図１０に示すようにそれぞれにガス供給口１１ｄを設けることが望ましい。或いは、前記アノード電極６の周壁部に開口する位置にガス供給口８を形成することもでき、また、それら複数のガス供給口８，１１ｄを組み合わせて複数形成することもできる。前記カソード電極１１の前記ガス供給口１１ｄからはキャリアガスのみを導入して、原料ガスは前記アノード電極６のガス供給口８、或いは別途、異なる導入口を設けて前記プラズマ発生室３の内部、成膜処理室４の内部、或いは前記プラズマ吹出口７の途中へと導入することもできる。
【０１２０】
なお、図９は複数の貫通孔１１ｂの形態を例示するものであり、全ての貫通孔１１ｂが異なる形態である図示の実施例に限定されるものではない。全ての貫通孔１１ｂが同一の形態であってもよく、或いは複数種類の貫通孔１１ｂが混在していてもよい。ノズル体１２の長さ寸法も、全ての貫通孔１１ｂにおいて同一であってもよく、或いは適宜長さを変化させ、基板表面へと到達するプラズマの強さを基板の全表面において均一化させることもできる。また、隔壁の形成位置及び形成数も同図９に限定されるものではなく、表面処理に必要なプラズマの強さに応じて自由に設計が可能である。
【０１２１】
更に、プラズマの強さを左右する因子として、高周波励起電源周波数を高めると結晶化が進むことは知られている。そこで、周波数を変更する実験を行った。
〈実験５〉
上述した実験１、２及び４では高周波励起電源周波数を１３．５６ＭＨｚとしていたが、これを１０５ＭＨｚに変更し、同一の条件で成膜を行ったところ、それぞれの実験における効果に更に高周波化による効果が加わり、成膜速度が２６０Å／sec.であっても薄膜が結晶化していた。また、成膜速度が２４０Å／sec.の場合には太陽電池として十分に機能し得る結晶膜が得られた。
【０１２２】
カソード電極１１が空洞体である上述した第３、第４実施例及びそれらの変形例では、図５、６及び９に示すように、カソード電極１１の空洞内部のほぼ全域においてホローカソード放電が発生している。しかしながら、前記カソード電極１１の空洞内部の高さ寸法や、貫通孔１１ｄの形状、数、及び配置、更には磁石１０の配置などによって、前記空洞内部の全域にわたってホロー放電が発生しない場合もあり、前記空洞内部の一部にのみホローカソード放電が発生し、或いは前記空洞内部において不均一にホローカソード放電が発生することもある。一般的傾向として、ホロー放電を起こしている貫通孔近傍の中空部では、空洞内部でも他よりも明るいホロー放電が発生している。
【０１２３】
図１１は、第５実施例による表面処理装置２３の概略図である。同装置２３は、カソード電極１１′の空洞内部にホローカソード放電が発生しないように、同空洞内部の内壁面を絶縁体により構成している点で上述した第３実施例と異なるが、その他の構成は上記第３実施例の表面処理装置２１と同一である。
【０１２４】
ただし、前記カソード電極１１′の下壁部１１ａ内面において一部電極を露出させてもよく、その場合には前記プラズマ発生室３において発生したプラズマが貫通孔１１ｂを通って空洞内部へと侵入し、その露出した電極面を這うことができる。それにより、プラズマが実質的に接触し得るカソード電極１１′の表面積を増大させることができ、自己バイアスの増大を図ることができる。
【０１２５】
また、前記カソード電極１１′の空洞内部にホローカソード放電を発生させないためには、上述のように内壁面を絶縁体で構成することの他にも、同空洞内部の高さＨを高くする方法が挙げられるが、この高さＨは、ＲＦパワーやガス圧によっても変化するため、内壁面を絶縁体で構成する方法がより確実である。
【０１２６】
このようにプラズマの発生場所を制御できると共に、カソード電極１１′のプラズマと接触する表面積をも調節でき、自己バイアスをも制御できるため、用途に応じた強さのプラズマを発生させることができる。
【０１２７】
〈実験６〉
上記表面処理装置２３を使用して、上述した実験２と同一の条件で成膜をおこなったところ、前記貫通孔１１ｂにおいてホローカソード放電が発生し、プラズマ吹出口７においてはホローアノード放電が発生して、プラズマの密度が高まり、微結晶薄膜を高速で成膜することが可能であった。また、得られた薄膜は太陽電池としても十分に機能し得るものであった。
【０１２８】
図１２は第６実施例による表面処理装置２４の概略図であり、この表面処理装置２４は上述した第５実施例の表面処理装置２３におけるカソード電極１１′の貫通孔１１ｂ及びプラズマ吹出口７の内周壁に磁石１０を配したものである。
【０１２９】
〈実験７〉
第６実施例の表面処理装置２４を使用して、上述した実験２と同一の条件で成膜を行ったところ、上述の実験６と比較して、成膜速度や電池効率が１０％以上向上した。
【０１３０】
なお、上述した空洞体であるカソード電極１１の変形例として、例えば図１３（ａ）に示す空洞体であるカソード電極１５のように、空洞内部に連通する複数の貫通孔１５ｂを有する下壁部１５ａと、上壁部１５ｃとの間を、一以上の貫通孔１５ｄを有する一以上の仕切り壁１５ｅにより上下に複数段に仕切ることができる。また、このとき、図１３（ｂ）に示す空洞体であるカソード電極１５′のように、下壁部１５ａに形成された複数の貫通孔１５ｂと、仕切り壁１５ｅに形成された複数の貫通孔１５ｄとが、上下方向に互いに重ならないようにそれぞれの貫通孔１５ｂ，１５ｄを形成することが好ましい。
【０１３１】
また、各貫通孔１５ｂ，１５ｄの数を下壁部１５ａと仕切り壁１５ｅとの間で異ならせてもよい。また、各貫通孔１５ｂ，１５ｄの開口寸法も下壁部１５ａと仕切り壁１５ｅとで異ならせてもよく、更には、下壁部１５ａの複数の貫通孔１５ｂや、仕切り壁１５ｅの複数の貫通孔１５ｄにおいても、全て均一の開口寸法とする必要はなく、開口寸法を中心部分から外縁方向に漸減又は漸増させるように変化させることもできる。
【０１３２】
上述した空洞体であるカソード電極１１の更に他の変形例として、図１３（ｃ）に示す空洞体からなるカソード電極１６のように、複数の中空電極部材１６ａを連結口１６ｂにより上下に複数段に連結することもできる。
【０１３３】
図１４は本発明の第７実施例による表面処理装置２５の概略図である。この表面処理装置２５も、ケーシング２内がプラズマ発生室３と基板処理室４との２室に画成されている。前記プラズマ発生室３内にはカソード電極５とアノード電極６′とが配され、前記アノード電極６′が前記プラズマ発生室３と基板処理室４とを画成している。同アノード電極６′の中心には円形のプラズマ吹出口７′が形成されており、このプラズマ吹出口７′を介して前記プラズマ発生室３と基板処理室４とが連通されている。
【０１３４】
前記カソード電極５は前記アノード電極６′との対向面に、断面が円形をなす複数の凹部５ａが形成されており、この凹部５ａの開口幅Ｗは、Ｗ≦５Ｌ(e) 又はＷ≦２０Ｘのいずれかを満足する範囲に設定されている。更に好ましくは、前記開口幅ＷはＸ／５≦Ｗの範囲に設定される。前記凹部５ａの直径をかかる範囲に設定することにより、前記凹部５ａにおいてホローカソード放電が発生する。
【０１３５】
本実施例の以上の構成は上述した第１実施例と同様であるが、前記アノード電極６′に形成されているプラズマ吹出口７′の開口幅Ｗが大きくため、又は長さ（厚み）Ｔが小さいため、同プラズマ吹出口７′においてホロー放電が発生していない点で上述した第１実施例の表面処理装置１とは異なるものである。
【０１３６】
本実施例では、プラズマ吹出口７′においてホロー放電が発生しないため、上述した第１実施例よりは表面処理の速度及び品質が若干劣るものの、カソード電極５の凹部５ａにおいてホローカソード放電が生じているため、従来の表面処理装置と比較すれば、その処理速度及び処理品質は向上している。
【０１３７】
なお、上述したいずれの実施例も表面処理装置の上方にプラズマ発生室３を、その下方に基板処理室４を設けているが、これら実施例とは逆に、下方にプラズマ発生室３を配して、その上方に基板処理室を設け、プラズマを下方から上方へと流出させるタイプの装置とすることも可能である。更には、表面処理装置のケーシングを左右二室に画成し、プラズマ発生室と基板処理室とを水平に配し、プラズマを横方向に流出させるタイプの装置とすることも可能である。いずれの場合にあっても、基板はプラズマ吹出口に対向させてプラズマの流出方向に直交して配することができ、或いは、基板をプラズマの流出方向と平行に配することも可能である。また、プラズマ発生手段も一対のプラズマ発生電極に限定されるものではなく、例えば三極以上の電極を有する放電、マイクロ波放電や容量結合型放電、誘導結合型放電、ＰＩＧ放電、電子線励起放電によるプラズマ発生手段なども採用できる。
【０１３８】
図１５（ａ）及び図１５（ｂ）に示すように、ホローカソード放電が発生するカソード電極５，１１のアノード電極側及び／又はその反対側の近傍に、他の電極１３を配することもできる。他の電極１３はカソード電極５に形成された凹部５ａ又は空洞体であるカソード電極１１に形成された貫通孔１１ｂの開口幅Ｗよりも小さな開口幅をもつ小孔１３ａが多数形成されている。或いは、前記他の電極１３はメッシュ状であってもよい。なお、ホローカソード放電が発生する貫通孔を有するカソード電極の場合であっても、同様に、前記貫通孔の開口幅Ｗよりも小さな小孔が多数形成された他の電極を配することもできる。
【０１３９】
他の電極１３はフローティング状態を含む任意の電圧にバイアスされており、特に好ましくは、接地されているアノード電極６の電圧とプラズマが有する空間電位の最大値との間の電圧値に設定され、或いは、ホローカソード放電が発生しているカソード電極５の電圧とプラズマの有する空間電位の最大値との間の電圧値に設定されている。
【０１４０】
更に、前記他の電極１３に形成されている小孔１３ａを図１５に示すように、カソード電極５，１１の凹部５ａ又は貫通孔１１ｂに対応する位置に形成すれば、電子が更にホローカソード放電域に閉じ込められて、いっそう大電流の放電である超高密度ホローカソード放電が可能になる。
【０１４１】
或いは、図１６（ａ）及び１６（ｂ）に示すように、カソード電極５″に形成された凹部５ａ″や、カソード電極１１″に形成された貫通孔１１ｂ″において、開口部分の面積が前記凹部５ａ″や貫通孔１１ｂ″の他の部分の断面積よりも十分小さく形成することにより、電子をホローカソード放電域である前記凹部５ａ″や前記貫通孔１１ｂ″内または中空部に効率よくに閉じ込めることができる。なお、同図では前記凹部５ａ″や貫通孔１１ｂ″はその上半部が円柱状で下半部が半球状であるが、円錐状や角錐状、更には紡錘形状としてもよい。
【０１４２】
図１７は本発明の第８実施例である表面処理装置２７の概略図である。同装置２７は、アノード電極１４がカソード電極５との対向部分が空洞体である点で上述した第１実施例と異なるが、その他の構成は上記第１実施例の表面処理装置１と略同一である。
【０１４３】
前記アノード電極１４は、カソード電極５との対向部分が空洞体１４ａとなっており、その空洞体１４ａの中心に、上壁部１４ｂと下壁部１４ｃとを一直線上に貫通する単一のプラズマ吹出口７が形成されている。更に、本実施例にあっては、前記アノード電極１４の空洞体１４ａの内部をホローアノード放電の発生域とし得るよう、前記空洞体１４ａの前記プラズマ吹出口７の形成方向に沿った対面距離、即ち図では上下の高さＨを、Ｈ≦５Ｌ(e) 又はＨ≦２０Ｘのいずれかを満足する範囲に設定している。但し、Ｌ(e) は所望のプラズマ発生条件下において、原料ガス種及びそこから分解発生する電気的に中性の原子、分子種（活性種）のうち最も直径の小さな原子又は分子種（活性種）に対する電子の平均自由行程であり、Ｘは所望のプラズマ発生条件下において発生するシース層の厚みである。前記空洞内部の高さＨは、Ｘ／２０≦Ｈの範囲に設定することが好ましく、更には、Ｘ／５≦Ｈの範囲に設定することが好ましい。
【０１４４】
本実施例においては、プラズマ吹出口７におけるホローアノード放電とカソード電極５の凹部５ａにおけるホローカソード放電とに加え、更に、アノード電極１４の空洞体１４ａの内部においてホローアノード放電が発生し、前記アノード電極１４の空洞体１４ａの内部においても新たなプラズマが発生している。そのため、基板Ｓへと到達するプロセスプラズマの密度が更に高まり、成膜処理に寄与する活性種が増加するため、表面処理速度が向上すると共に、その処理品質も更に向上する。
【０１４５】
なお、図示例では前記空洞体１４ａの内部高さＨを一定にしているが、前記高さＨは一定でなくてもよい。ホローアノード放電を空洞体１４ａの内部の略全域にわたって均一に発生させるために、印加電力の周波数に応じて、或いは、その他の条件によって、中心付近での空洞内部の高さＨを小さくし外縁方向にその高さＨを漸増させ、或いは、中心付近で高さＨを大きくし外縁方向にその高さＨを漸減させることが好ましい。
【０１４６】
或いは、前記空洞体１４ａはその内部全体においてホローアノード放電を発生させる必要は無く、少なくとも一部においてホローアノード放電を発生させることができれば、表面処理の品質及び処理速度の向上が認められる。
【０１４７】
図１８は上述した空洞体であるアノード電極１４の変形例である。上述したアノード電極１４は空洞体１４ａの中心に単一のプラズマ吹出口７を貫通して形成していたが、図１８に示すアノード電極１４′のように、空洞体１４ａの上壁部１４ｂと下壁部１４ｃとにそれぞれ空洞内部に連通する、プラズマ吹出口としての複数の貫通孔１４ｄを形成することも可能である。なおこの場合、上壁部１４ｂの貫通孔１４ｄと下壁部１４ｃの貫通孔１４ｄとは上下に一直線上に並ばないように互いにずらして形成することが好ましい。更に、貫通孔１４ｄを図３２〜図３５の配列で形成することが好ましい。
【０１４８】
また、複数の前記貫通孔１４ｄは開口幅Ｗが全て同一でなくてもよく、複数の前記貫通孔１４ｄにおいて均一にホローアノード放電を発生させるために、適宜、異なる開口幅Ｗに設定することができる。特に、印加電力の周波数に応じて、或いは、その他の条件によって、中心付近の貫通孔１４ｄは開口幅Ｗを小さくし外縁方向にその開口幅Ｗを漸増させ、或いは、中心付近で開口幅Ｗを大きくし外縁方向にその開口幅Ｗを漸減させることが好ましい。
【０１４９】
また、前記貫通孔１４ｄの長さＴ、すなわち本実施例の場合には前記下壁部１４ｂの厚みＴは概ねＸ／５０を下限とする。上限は装置寸法上の制約によって決定される。この貫通孔１４ｄの長さＴは上述したガス圧及び直径の場合には、０．１〜７０ｍｍが好ましい。
【０１５０】
なお、本実施例にあっては前記貫通孔１４ｄは円形断面であるが、他にも楕円形、矩形、多角形、不定形状など任意の形状とすることができる。断面積も一定でなくてもよく、軸線方向に断面積を変化させてもよい。更には、前記貫通孔１４ｄを断面が矩形状のスリット構造としたり、或いは図３６に示すような渦巻き形状、蛇行状などの一次元的広がりをもつスリット構造とすることもできる。このようなスリット構造とする場合には、その貫通孔１４ｄの開口幅Ｗとはスリット幅であり、このスリット幅を上述の範囲内で設定する。また、前記貫通孔１１ｂの内壁面に部分的な凹凸を形成してもよい。複数の前記貫通孔１４ｄは、互いに同一寸法及び同一形態とする必要は無く、異なる寸法及び形態をもつ貫通孔１４ｄを複数形成してもよい。
【０１５１】
前記アノード電極１４′には、前記貫通孔１４ｄの内壁面や空洞体１４ａの内部に開口するガス供給口８′を形成することができる。例えば成膜処理の場合には、前記プラズマ発生室３へはキャリアガスのみを導入し、前記アノード電極１４′のガス供給口８′からはモノシラン等の原料ガスを導入することにより、同原料ガスの不要な空間での分解を防止し、原料ガスを効率よく成膜処理に寄与させることができる。なお、複数の貫通孔１４ｄの全てにガス供給口８′を設けることもでき、あるいは一部の貫通孔１４ｄにのみガス供給口８′を設けることもできる。更に、空洞体１４ａの内壁面には複数のガス供給口８′を開口させることもできる。
【０１５２】
更に、アノード電極１４′における空洞体１４ａ内部及び貫通孔１４ｄでのホローアノード放電により生じるプラズマ密度を大きくする変形例を、図１９（ａ）及び図１９（ｂ）に示す。
先ず、前記貫通孔１４ｄにおいてホローアノード放電を効率良く発生させる観点からは、前記貫通孔１４ｄの長さＴは大きいほうが有利であり、より強いプラズマを発生させることができる。しかしながら、前記アノード電極の上下壁部１４ｂ，１４ｃの厚みは、材料コストの観点からも空洞内部に導入されるガス圧及び印加電力に耐え得る最小の厚みにすることが望ましい。
【０１５３】
そのため、前記貫通孔１４ｄの長さＴを長くするためには、下壁部１４ｃの貫通孔１４ｄの周縁にノズル体１２を取り付けることが望ましい。なお、このノズル体１２は前記貫通孔１４ｄから基板処理室４側へ突設してもよく、或いは空洞体１４ａの内部へ突設することもできる。更には両側へ突設してもよい。また、同ノズル体１２を図１９（ａ）に示すように磁石１０により構成することもできる。このとき、磁石１０は直接プラズマに晒されないように配することが好ましい。
【０１５４】
なお、図１９（ａ）に示すノズル体１２はいずれも、その中心線を貫通孔１４ｄの線と一致させて配しているが、前記ノズル体１２の中心線を前記貫通孔１４ｄの軸線に対して角度をもって配する、即ち、ノズル体１２を斜めに配することもできる。また、図１９（ａ）に示すノズル体１２は断面積が一定の筒体であるが、かかる形状に限定されるものではなく、その断面積を漸増又は漸減させる形状をもつ筒体であってもよい。更にはチューブ状のノズル体をらせん状に配することもできる。
【０１５５】
更に、プラズマが接触するアノード電極１４′の表面積を増大させるために、前記アノード電極１４′の空洞体１４ａの内部に、上下方向に延びる隔壁や、水平方向に延びる隔壁を設けて、内部を複数室に分割することもできる。なお、内部の分割された各室に形成されている貫通孔１４ｄは全て同一であってもよく、或いは異ならせることもできる。また、上下方向に延びる前記隔壁は、前記空洞体１４ａの上下壁部１４ｂ，１４ｃとの間に隙間が形成され、各室が連通していてもよい。
【０１５６】
また、前記アノード電極１４′には、図１９（ｂ）に示すように、プラズマ吹出口である前記貫通孔１４ｄや空洞体１４ａの内部に磁場を付与するように磁石１０を各貫通孔１４ｄの内周面、前記空洞体１４ａの上下壁部１４ｂ，１４ｃ、或いは周壁部に埋設したり、それらの近傍に配することができる。前記磁石１０は、その磁力線の方向が貫通孔１４ｄの軸線方向と平行になるように磁場が印加されるよう、或いは磁力線の方向が前記上下壁部１４ｂ，１４ｃと平行になるように磁場が印加されるよう、配されていることが好ましい。
【０１５７】
このように貫通孔１４ｄや空洞体１４ａの内部に磁場を形成することにより、そこに発生しているプラズマ内の電子の軌道を前記磁場により調整し、前記貫通孔１４ｄや空洞体１４ａの内部に電子を長く留まらせることができる。この電子の軌道調整により、電子のエネルギー（電子温度）を高めることなく、原料ガスへの電子の作用時間を長くできるため、活性種の生成が促進され、成膜速度が向上する。
【０１５８】
図２０〜図２２は上述した第８実施例の第１〜第３変形例による表面処理装置２８〜３０の概略図である。図２０に示す表面処理装置２８は、第８実施例のカソード電極５を空洞体のカソード電極１１に変更し、同カソード電極１１の空洞内部及び同カソード電極１１に形成された貫通孔１１ｂをホローカソード放電域としたものである。
【０１５９】
図２１に示す表面処理装置２９は、第８実施例のカソード電極５を空洞体をなし且つその空洞内部の内壁面を絶縁したカソード電極１１′に変更し、同カソード電極１１′に形成された貫通孔１１ｂをホローカソード放電域としたものである。また、図２２に示す表面処理装置３０は、第８実施例のカソード電極５を単なる平板状の電極５′に変更し、同カソード電極５′ではホローカソード放電は発生させず、ホローアノード放電のみを発生させている。
【０１６０】
これらの変形例はいずれも、第８実施例と上述した本発明の他の実施例との組み合わせであり、それぞれ、上述したような各実施例における作用効果を兼ね備えている。従って、いずれの変形例にあっても、ホローアノード放電やホローカソード放電によって、プロセスプラズマの密度が高まり、各種処理速度が著しく向上する。
【０１６１】
図２３は本発明の第９実施例である表面処理装置４０の概略図である。同表面処理装置４０は、空洞状のアノード電極１７の内部が基板処理室４′を構成している。
空洞状のアノード電極１７は上壁部１７ａの中心に貫通孔１７ｂが形成されており、この貫通孔１７ｂがプラズマ吹出口を構成している。また、同アノード電極１７の下壁部１７ｃの内面中央部分が基板支持台を構成すると共に、同下壁部１７ｃの周縁部分には複数の排気口１７ｄが形成されている。また、同下壁部１７ｃの中央部分には基板の加熱手段を内装させることもできる。なお、アノード電極１７内の基板の支持位置や排気口１７ｄの形成位置は上述のものに限定されるものではなく、任意の位置を選択できる。
【０１６２】
本実施例にあっては、前記アノード電極１７の貫通孔１７ｂをホローアノード放電の発生域とし得るよう、前記貫通孔１７ｂの開口幅Ｗを、Ｗ≦５Ｌ(e) 又はＷ≦２０Ｘのいずれかを満足する範囲に設定している。更に前記開口幅Ｗは、Ｘ／２０≦Ｗの範囲に設定することが好ましく、Ｘ／５≦Ｗの範囲に設定することがより好ましい。また、本施例にあっては、前記アノード電極１７の空洞内部をもホローアノード放電の発生域とし得るよう、前記空洞内部の高さＨを、Ｈ≦５Ｌ(e) 又はＨ≦２０Ｘのいずれかを満足する範囲に設定している。前記空洞内部の高さＨも、Ｘ／２０≦Ｈの範囲に設定することが好ましく、更には、Ｘ／５≦Ｈの範囲に設定することが好ましい。
【０１６３】
但し、Ｌ(e) は所望のプラズマ発生条件下において、原料ガス種及びそこから分解発生する電気的に中性の原子、分子種（活性種）のうち最も直径の小さな原子又は分子種（活性種）に対する電子の平均自由行程であり、Ｘは所望のプラズマ発生条件下において発生するシース層の厚みである。
【０１６４】
同基板処理装置４０では、基板処理室４′をアノード電極１７の空洞内部に形成し、このアノード電極１７の空洞内部にはホローアノード放電を発生させているため、基板Ｓの処理に寄与するプラズマの密度が極めて高まるため、処理速度も著しく向上する。但し、この基板処理装置４０では、プラズマによる基板Ｓへのイオンダメージが大きいため成膜処理には不適であり、同装置４０はエッチング、アッシング又はイオンドーピングの処理に適している。
【０１６５】
図２４（ａ）及び図２４（ｂ）は基板処理室４′を構成する空洞状のアノード電極の変形例である。図２４（ａ）に示すアノード電極１７′は上壁部１７ａにプラズマ吹出口を構成する複数の貫通孔１７ｂが形成されている点で上述のアノード電極１７とは異なる。なお、前記貫通孔１７ｂは図３２〜図３５に示すような配置で形成することが好ましい。
【０１６６】
この複数の貫通孔１７ｂは、本実施例にあっては円形断面であるが、他にも楕円形、矩形、多角形、不定形状など任意の形状とすることができる。断面積も一定でなくてもよく、軸線方向に断面積を変化させてもよい。更には、前記貫通孔１７ｂを断面が矩形状のスリット構造としたり、或いは図３６に示すような渦巻き形状、蛇行状などの一次元的広がりをもつスリット構造とすることもできる。このようなスリット構造とする場合には、その貫通孔１７ｂの開口幅Ｗとはスリット幅であり、このスリット幅を上述の範囲内で設定する。また、前記貫通孔１７ｂの内壁面に部分的な凹凸を形成してもよい。複数の前記貫通孔１７ｂは、互いに同一寸法及び同一形態とする必要は無く、異なる寸法及び形態をもつ貫通孔１７ｄを複数形成してもよい。
【０１６７】
また、図２４（ｂ）に示すアノード電極１７″は、プラズマ吹出口である前記貫通孔１７ｂや排気口１７ｄ、空洞内部に磁場を付与するように磁石１０を各貫通孔１７ｂや排気口１７ｄの内周面、前記空洞内部の上下壁部１７ａ，１７ｃ、或いは周壁部に埋設したり、それらの近傍に配することができる。前記磁石１０は、その磁力線の方向が貫通孔１７ｂや排気口１７ｄの軸線方向と平行になるように磁場が印加されるよう、或いは磁力線の方向が前記上下壁部１７ａ，１７ｄと平行になるように磁場が印加されるよう、配されていることが好ましい。
【０１６８】
このようにプラズマ吹出口である貫通孔１７ｂや空洞内部に磁場を形成することにより、そこに発生しているプラズマ内の電子の軌道を前記磁場により調整し、前記貫通孔１７ｂや空洞内部に電子を長く留まらせることができる。この電子の軌道調整により、電子のエネルギー（電子温度）を高めることなく、原料ガスへの電子の作用時間を長くできるため、活性種の生成が促進され、成膜速度が向上する。
【０１６９】
図２５は、各種貫通孔でのホロー放電を発生しやすくするための変形例を示している。同図２５ではアノード電極６に形成されたプラズマ吹出口７を例に説明する。
図２５（ａ）に示す変形例では、アノード電極６の下面にプレート状の絶縁体１８を密着されて配しており、更に、同絶縁体１８の下面に金属プレートからなる他の電極１９を配している。プラズマ吹出し口７はこれらアノード電極６、絶縁体１８、及び他の電極１９を貫通して形成されている。この他の電極１９には前記アノード電極の電位よりも低い電位となるように、直流バイアスや交流バイアス（高周波やパルスを含む）を印加している。
【０１７０】
ここで、プラズマの電位はそのプラズマの大部分が接する電極の電位、即ち、この場合、アノード電極６の電位によって決まる。このアノード電極６の面積に比べてプラズマ吹出口７はプラズマとの接触面積が極めて小さいが、このプラズマ吹出口７にバイアスを印加してプラズマの電位とプラズマ吹出口との間の電位差を自由に制御することが可能になる。従って、通常はプラズマの電位とアノード電極６との電位差が小さくて、プラズマ吹出口７においてホロープラズマが発生し得ない低パワーの放電であっても、前記他の電極１９にバイアスを印加してプラズマとプラズマ吹出口７との電位差を大きくすることができるため、同プラズマ吹出口７のホロープラズマの発生を誘起することができる。
【０１７１】
なお、プラズマ吹出口７の電位を自在に設定し得る他の電極の配置例としては、他にも図２５（ｂ）に示すように、アノード電極６のプラズマ吹出口７の形成部分の下面にのみ、リング状の絶縁体１８ａとリング状の他の電極１９ａとを重ねて配することもできる。
【０１７２】
また、図２５（ｃ）に示すように、アノード電極６のプラズマ吹出口７の内壁面にリング状の絶縁体１８ｂを介してリング状の他の電極１９ｂを配してもよく、或いは、図２５（ｄ）に示すように、アノード電極６のプラズマ吹出口７の内壁面にリング状の絶縁体１８ｂを介して円筒ノズル状の他の電極１９ｃを配することもできる。
なお、かかる構造はアノード電極に複数の貫通孔を形成した場合や、カソード電極に形成された貫通孔などの各種貫通孔に同様に適用が可能である。
【０１７３】
以上説明した本発明の各種実施例及び変形例では、プラズマ発生電極には高周波電源Ｐにより高周波電力を投入しているが、直流電源により直流電圧を印加することもできる。或いは、それぞれ直流や交流の電源又はパルス電源によってバイアスを印加してもよい。
また、表面処理室４に配された基板Ｓとプラズマ吹出口７との間にメッシュ状の電極を設置してトライオード型に構成し、また様々なバイアスを印加することも可能である。
【０１７４】
更には、上述した実施例ではいずれも、表面処理装置のケーシング２の内部をアノード電極６により上下に２分割して上方をプラズマ発生室３、下方を基板処理室４としているが、本発明はかかる装置に限定されるものではない。
【０１７５】
図２６〜図３１には本発明の他の実施例による表面処理装置の水平方向の断面図を示す。
図２６に示す本発明の第１０実施例である表面処理装置４１は、ケーシング３２が有底の円筒体からなり、その周壁内面を基板支持台９としている。この場合に、前記ケーシング３２の内部には、小径円柱体からなるカソード電極３５と、同カソード電極３５よりも大径の円筒体かならるアノード電極３６とを、中心軸線を一致させて配している。
【０１７６】
前記アノード電極３６には所定の形状と配置を有する複数のプラズマ吹出口３７が形成され、前記アノード電極３６と前記ケーシング３２との間の領域が本発明における基板処理室３４を構成すると共に、前記カソード電極３５と前記アノード電極３６との間の領域が本発明におけるプラズマ発生室３３を構成する。更に、前記カソード電極３５の周壁面には複数の軸線方向に平行な凹部３５ａが所定の位相差をもって形成されている。なお、前記カソード電極３５を空洞体とした場合には、前記凹部３５ａに変えて貫通孔を形成すると共に、その空洞内部にキャリアガス及び原料ガスを供給してもよい。
【０１７７】
或いは、図２７に示す本発明の第１１実施例による表面処理装置４２のように、最大径の円筒体をカソード電極３５とし、その内部に軸線を一致させて円筒体からなるアノード電極３６を配し、更にその中心に最小径の円柱体３９を配することもできる。この場合には中心の円柱体３９の外周面が基板Ｗの支持台を構成する。前記カソード電極３５の内周面には複数の軸線方向に平行な凹部３５ａが所定の位相差をもって形成されている。前記アノード電極３６には所定の形状と配置を有するプラズマ吹出口３７を形成する。なお、前記カソード電極３５の更に外側にケーシングを配することもできる。
【０１７８】
この図２６及び図２７に示す第１０及び第１１実施例にあっても、前記プラズマ吹出口３７の開口幅を本発明の規定する上記範囲内とすることにより、同吹出口３７においてホローアノード放電が発生する。また、前記凹部３５ａにおいても、その開口幅を本発明の範囲内とすることにより、同凹部３５ａにおいてホローカソード放電が発生する。
【０１７９】
更に、前記アノード電極３５やカソード電極３６を空洞体により形成し、互いの電極との対向面に貫通孔を形成してその貫通孔でホロー放電を発生させ、更には、空洞内部の少なくとも一部でホロー放電を発生させることもできる。その場合には、表面処理に寄与するプラズマがより高密度となり、表面処理の速度が向上する。
【０１８０】
かかるカソード電極３５及びアノード電極３６が円筒体からなる装置は、感光ドラムのような円筒形状の基板に表面処理を施す際に有用である。或いは、円筒の一部の曲面を利用することにより、帯状フィルム部材からなる基板にロール・ツー・ロールで連続的に成膜やエッチングなどの表面処理を施す場合に、装置スペースの低減が可能となるため、好ましい。
【０１８１】
また、各プラズマ発生電極を上述した図２６及び図２７に示すような断面形態をもつ球形状とすることもでき、或いは、図２８及び図２９に示す本発明の第１２及び第１３実施例による表面処理装置４３，４４のように、各プラズマ発生電極３５，３６を断面が半円形状の筒体や半球体など曲面の一部となる形状とすることもできる。このようにプラズマ発生電極を球形状や半球形状とし、或いは一部を曲面とすることにより、球面半導体のような特殊な形状の基板にも均一な表面処理を施すことが可能になる。
【０１８２】
更には、図３０及び図３１に示す本発明の第１４及び第１５実施例による表面処理装置４５，４６のように、プラズマ発生電極３５，３６を断面が正方形の筒体とすることもできる。或いは断面が多角形状の筒体や多面体形状とすることもできる。このようにプラズマ発生電極３５，３６を角形状とすることにより、装置スペースの低減が可能となる。また、それら多様な形状のプラズマ発生電極３５，３６を空洞体から構成し、互いの電極との対向面に貫通孔を形成してその貫通孔でホロー放電を発生させ、更には、空洞内部の少なくとも一部でホロー放電を発生させて、プラズマの高密度化を図ることも可能である。
【図面の簡単な説明】
【図１】 本発明の第１実施例である表面処理装置の概略図である。
【図２】 上記装置の変形例によるガス供給口の配置例を示す概略図である。
【図３】 本発明の第２実施例である表面処理装置の概略図である。
【図４】 カソード電極に対する磁石の他の配置態様を示す概略図である。
【図５】 本発明の第３実施例である表面処理装置の概略図である。
【図６】 本発明の第４実施例である表面処理装置の概略図である。
【図７】 空洞状のカソード電極に対する磁石の他の配置態様を示す概略図である。
【図８】 空洞状のカソード電極に対する磁石の更に他の配置態様を示す概略図である。
【図９】 上記第３及び第４実施例の装置の変形例によるカソード電極の概略図である。
【図１０】 上記変形例でのガス供給口の配置例を示す概略図である。
【図１１】 本発明の第５実施例である表面処理装置の概略図である。
【図１２】 本発明の第６実施例である表面処理装置の概略図である。
【図１３】 空洞状のカソード電極の他の態様を示す概略図である。
【図１４】 本発明の第７実施例である表面処理装置の概略図である。
【図１５】 本発明の他の実施例による表面処理装置におけるカソード電極部分の概略図である。
【図１６】 本発明の更に他の実施例による表面処理装置におけるカソード電極部分の概略図である。
【図１７】 本発明の第８実施例である表面処理装置の概略図である。
【図１８】 上記第８実施例におけるアノード電極の変形例を示す概略図である。
【図１９】 上記第８実施例におけるアノード電極の他の変形例を示す概略図である。
【図２０】 上記第８実施例の第１変形例である表面処理装置の概略図である。
【図２１】 上記第８実施例の第２変形例である表面処理装置の概略図である。
【図２２】 上記第８実施例の第３変形例である表面処理装置の概略図である。
【図２３】 本発明の第９実施例である表面処理装置の概略図である。
【図２４】 上記第９実施例におけるアノード電極の変形例を示す概略図である。
【図２５】 本発明の各種貫通孔における好適な変形態様を示す概略図である。
【図２６】 本発明の第１０実施例による表面処理装置の水平方向の概略断面図である。
【図２７】 本発明の第１１実施例による表面処理装置の水平方向の概略断面図である。
【図２８】 本発明の第１２実施例による表面処理装置の水平方向の概略断面図である。
【図２９】 本発明の第１３実施例による表面処理装置の水平方向の概略断面図である。
【図３０】 本発明の第１４実施例による表面処理装置の水平方向の概略断面図である。
【図３１】 本発明の第１５実施例による表面処理装置の水平方向の概略断面図である。
【図３２】 多数の貫通孔又は凹部の配置例を示す図である。
【図３３】 多数の貫通孔又は凹部の他の配置例を示す図である。
【図３４】 多数の貫通孔又は凹部の更に他の配置例を示す図である。
【図３５】 多数の貫通孔又は凹部の更に他の配置例を示す図である。
【図３６】 渦巻き状の貫通孔又は凹部の説明図である。
【符号の説明】
１，20〜30，40〜46 表面処理装置
２ ケーシング
２ａ 上壁
２ｂ 周壁
３ プラズマ発生室
４ 基板処理室
５ カソード電極
５ａ 凹部
６ アノード電極
７ プラズマ吹出口
８ ガス供給口
９ 基板支持台
１０ 磁石
１１ カソード電極
１１ａ 下壁部
１１ｂ 貫通孔
１１ｃ 上壁部
１１ｄ ガス供給口
１１ｅ 隔壁
１２ ノズル体
１３ 他の電極
１３ａ 小孔
１４ アノード電極
１４ａ 空洞体
１４ｂ 上壁部
１４ｃ 下壁部
１４ｄ 貫通孔
１５ カソード電極
１５ａ 下壁部
１５ｂ 貫通孔
１５ｃ 上壁部
１５ｄ 貫通孔
１５ｅ 仕切り壁
１６ カソード電極
１６ａ 中空電極部材
１６ｂ 連結口
１７ アノード電極
１７ａ 上壁部
１７ｂ 貫通孔
１７ｃ 下壁部
１７ｄ 排気口
１８ プレート状の絶縁体
１８ａ リング状の絶縁体
１８ｂ リング状の絶縁体
１９ プレート状の他の電極
１９ａ リング状の他の電極
１９ｂ リング状の他の電極
１９ｃ 円筒ノズル状の他の電極
３２ ケーシング
３３ プラズマ発生室
３４ 基板処理室
３５ カソード電極
３５ａ 凹部
３６ アノード電極
３７ プラズマ吹出口
３９ 基板支持台
Ｓ 基板
Ｐ 高周波電源[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a surface treatment apparatus suitable for various surface treatments on a substrate, particularly a film formation treatment on a substrate, and more particularly to a surface treatment apparatus capable of forming a crystalline thin film with high quality and high speed. Is.
[0002]
[Prior art]
  2. Description of the Related Art Conventionally, surface treatment apparatuses that perform surface treatments such as etching and film formation by applying high-frequency power to parallel plate electrodes to bring the reaction gas into a plasma state and decomposing it into chemically active ions and radicals are known. .
[0003]
  For example, in a conventional parallel plate type plasma CVD (Chemical Vapor Deposition) apparatus for performing a film forming process, a pair of plate-like plasma generating electrodes are provided in parallel in a casing. One of the plasma generating electrodes also has a function as a substrate support, and the apparatus is further provided with a heater for adjusting the temperature of the substrate to a temperature suitable for vapor phase growth. . When electric power from a high-frequency power source (13.56 MHz power source) is applied between the two plasma generating electrodes while the substrate is placed on the one electrode, plasma is generated between these electrodes, For example, monosilane gas is activated and a silicon film is formed on the substrate surface.
[0004]
  In such a conventional parallel plate type plasma CVD apparatus, a large area substrate is formed by a single film formation process by increasing the area of the flat plate-like plasma generating electrode on which the substrate is placed. Has the advantage of being able to However, in the conventional parallel plate type plasma CVD apparatus, the source gas converted into plasma by the two plasma generating electrodes is uniformly diffused into the film forming gas processing chamber, and a part thereof is placed on the electrode. It only contributes to the deposition of the substrate. For this reason, the utilization efficiency of the source gas is low. For example, when an amorphous silicon thin film or a crystalline silicon thin film is to be formed on a substrate, the film formation rate is about 1 to 2 liters / sec. The film formation speed is slow. For this reason, it takes a long time to manufacture relatively thick semiconductor devices such as solar cells.whileIt was the main factor of low throughput and high cost.
[0005]
  Therefore, it is conceivable to increase the input power from the high-frequency power source in order to increase the film forming speed. However, increasing the input power increases the energy of charged particles in the plasma. Damage caused by the collision of the charged particles having high energy with the substrate deteriorates the film quality. Furthermore, with the increase of the high frequency power from the high frequency power source, a large amount of fine powder is generated in the gas phase, and the deterioration of the film quality due to the fine powder is also drastically increased.
[0006]
  Therefore, in the conventional parallel plate type plasma CVD apparatus, in order to avoid the damage caused by the collision of such high energy charged particles and the deterioration of the film quality due to the fine powder, the input power must be suppressed. That is, there is substantially an upper limit value of input power, and the film formation rate cannot be increased to a certain level or more.
[0007]
  Further, in the etching apparatus using parallel plate type plasma, since the degradation of the processing quality due to the increase of the input power is smaller than that of the film forming process, the processing speed can be increased to some extent by increasing the input power. However, at present, further improvement in the processing speed is desired for the purpose of improving the quality of the etching process, improving the manufacturing efficiency, and reducing the manufacturing cost.
[0008]
  On the other hand, a photovoltaic device forming device for a strip-shaped member, which is a traveling object to be processed, disclosed in Japanese Patent Application Laid-Open No. 11-145492 has a surface area in a discharge space of a high-frequency power application electrode (cathode electrode). Is larger than the surface area in the discharge space of the entire anode electrode including the belt-shaped member, and the potential of the cathode electrode when the glow discharge occurs is maintained at a positive potential of +30 V or more with respect to the grounded anode electrode including the belt-shaped member. ing. Furthermore, a plurality of threshold electrodes are installed on the cathode electrode in a direction perpendicular to the traveling direction of the belt-shaped member, and a discharge is caused between adjacent threshold electrodes. In this way, the cathode electrode is maintained at a positive potential of +30 V or more with respect to the band-shaped member and the anode electrode, and the above-described cathode electrode structure having the threshold-shaped electrode is used. It promotes excitation and decomposition reactions of material gases.
[0009]
  It is considered that the photovoltaic device forming apparatus disclosed in the above-mentioned publication certainly improves the film formation rate by promoting the excitation and decomposition reaction of the material gas on the anode electrode side including the belt-shaped member. However, since glow discharge is also generated in the space between the belt-like member and the cathode electrode, damage due to collision of charged particles is unavoidable.
[0010]
  Therefore, for example, a thin film forming apparatus disclosed in Japanese Patent Application Laid-Open No. 61-32417 is an activated gas comprising a definition chamber having a pair of opposed plasma generating electrodes in a vacuum chamber for forming a thin film on a substrate. A generator is arranged. A single pore for ejecting the activated gas into the vacuum chamber is formed in one wall portion of the activated gas generator. A substrate is supported in the vacuum chamber at a position facing the pores.
[0011]
  In the thin film forming apparatus, high frequency power is applied to the pair of plasma generating electrodes, and a glow discharge is generated between the electrodes to generate plasma. The source gas introduced into the activated gas generator is decomposed by this plasma. At this time, by adjusting the vacuum pump disposed in the vacuum chamber and the conductance of the pores, the vacuum degree of the vacuum chamber is lowered by two to three orders of magnitude lower than that of the activated gas generator, The converted source gas is ejected from the pores toward the substrate.
[0012]
  A plasma generating electrode is arranged inside the activated gas generator defined in the vacuum chamber for forming a thin film in this way, and the source gas activated in the activated gas generator is actively directed toward the substrate. In the thin film forming apparatus to be sprayed, the deposition rate can be increased without increasing the input power. Furthermore, even when the input power is increased to generate stronger plasma, the plasma generating electrode is installed in the defined activated gas generator, and the substrate is generated by glow discharge between the electrodes. There is no risk of damage to Therefore, it is possible to further increase the deposition rate by increasing the input power. In addition, although the film formation rate is increased, crystallization of the thin film is also promoted, and a high-quality thin film can be formed at a higher film formation rate than conventional.
[0013]
[Problems to be solved by the invention]
  Thus, although the film formation speed is increased by defining the plasma generation chamber and the film formation processing chamber, further improvement of the film formation speed is desired. High-speed deposition of microcrystalline thin films is strongly desired.
  Therefore, an object of the present invention is to provide a surface treatment apparatus capable of performing surface treatment with higher speed and higher quality in order to achieve such a demand.
[0014]
[Means for solving the problems and effects]
  To solve this problem,This caseAccording to the first aspect of the present invention, a plasma is generated by the plasma generating means in a casing having a plasma generating means, a raw material gas inlet, and a substrate support base, thereby converting the raw material gas into a plasma, on the substrate support base. A surface processing apparatus for plasma processing a surface of a substrate mounted thereon, wherein the casing includes a plasma generation chamber provided with the plasma generation means and a substrate processing chamber provided with the substrate support.Through the anode electrodeThe substrate processing chamber and the plasma generation chamber are defined in two chambers.Formed on the anode electrodeIt is communicated via one or more plasma outlets, and at least one of the plasma outlets is not a hollow discharge generation area.The plasma generation chamber is provided with a hollow plasma generation electrode having one or more hollow discharge generation regions.It is characterized by becoming.
[0015]
  In the present invention, “hollow discharge” refers to a phenomenon in which plasma, particularly found in through holes, recesses, and cavities, is strongly generated and the density of plasma increases.
  As the plasma generation means, discharge by a pair of plasma generation electrodes composed of a cathode and an anode, discharge having three or more electrodes, microwave discharge, capacitively coupled discharge, inductively coupled discharge, helicon wave discharge, PIG discharge, Means such as electron beam excited discharge can be employed.
[0016]
  The plasma outlet is formed in a partition wall between the substrate processing chamber and the plasma generation chamber.. ThisThe hollow discharge generated at the plasma outlet is caused by the potential at the plasma outlet.RihoLow anode discharge.
[0017]
  For example, when a pair of plasma generating electrodes consisting of a cathode and an anode is adopted as the plasma generating means,Anode electrodeAs the partition walladopt.When an anode electrode is used as the partition and the plasma outlet is formed on the anode electrode, the hollow discharge is a hollow anode glow discharge.It becomes. In addition,In the present invention, the electrode on the side to which the main power for discharging is applied is a cathode electrode, and the electrode facing the cathode electrode is an anode electrode.The
[0018]
  In order to perform the surface treatment by the surface treatment apparatus, first, the raw material gas and the carrier gas are injected into the casing through the gas supply pipe, and plasma is generated in the plasma generation chamber by the plasma generation means. At this time, in the surface treatment apparatus of the present invention, since the plasma generation chamber and the substrate processing chamber are defined, the carrier gas and the source gas can be efficiently used. Is promoted.
[0019]
  The plasma generated in the plasma generation chamber flows out from the plasma outlet to the substrate processing chamber by the flow of internal gas due to exhaust from the substrate processing chamber, the differential pressure between the two chambers, or by diffusion. At this time, by supplying appropriate gas flow rate, gas pressure, and plasma parameters, the plasma in the plasma generation chamber is smoothly transported from the plasma outlet to the substrate processing chamber.
[0020]
  The source gas can be introduced until the plasma generated in the plasma generation chamber blows out to the substrate processing chamber and reaches the substrate surface. The activated source gas in the plasma reaches the substrate surface in the processing chamber by the plasma flow, and the substrate is subjected to surface treatment such as etching or film formation.
[0021]
  In the invention according to claim 1, it is important to generate a hollow discharge in at least one of the plasma outlets. Since this hollow discharge newly generates plasma at the plasma outlet, the density of the plasma guided to the substrate processing chamber is increased. Furthermore, when the plasma generated in the plasma generation chamber passes through the plasma outlet where the hollow discharge is generated, the energy of charged particles (electrons or ions) in the plasma is reduced due to interaction due to collision or the like. . By reducing the energy of the electrons, the electrons are sufficient to generate neutral active species that contribute to the surface treatment from the source gas, and the ions that collide and damage the substrate surface are less likely to be generated. As a result, the number of neutral active species can be increased without increasing ions. Also, by reducing the number of high energy ions in the plasma, the effects of substrate damage due to these ions can be reduced.
[0022]
  Thus, the hollow discharge increases the plasma density and neutral active species that contribute to the surface treatment, thereby increasing the surface treatment speed. Further, by reducing the energy of ions present in the plasma that collide with the substrate and cause damage, deterioration of the substrate surface can be suppressed, and high-quality surface treatment can be performed at high speed.
[0023]
  AboveIt is important to arrange a hollow plasma generating electrode in the plasma generating chamber. For example, a pair of plasma generating electrodes consisting of an anode and a cathode are used as plasma generating means.Adopt both electrodesIn each case, it is necessary to generate a hollow discharge. By generating the hollow discharge, plasma is newly generated in the hollow discharge generation region, so that the density of the plasma guided to the substrate processing chamber is increased, and the active species contributing to the surface treatment is increased. The speed of the surface treatment is further increased.
[0024]
  Furthermore, not only the hollow discharge at the plasma outlet, but also the hollow discharge at the hollow plasma generating electrode occurs, so that the following synergistic effects can be obtained in addition to the functions and effects of the respective discharges described above. Is. In other words, in addition to the hollow discharge at the plasma outlet, hollow discharge occurs at the hollow plasma generation electrode, thereby lowering the electron temperature and increasing the electron density in the hollow discharge region of the electrode. Will improve. Furthermore, for example, when the cathode electrode is a hollow plasma generating electrode and a hollow discharge is generated at the cathode electrode, the high-frequency voltage at the cathode electrode is decreased and the self-bias voltage is increased. The space potential of the plasma also increases. As a result, hollow discharge is likely to occur at the plasma outlet, and high-density plasma can be generated at the plasma outlet. For the same reason, electric field concentration is likely to occur in the plasma generating chamber, and non-uniform discharge that is locally converted to high-density plasma can be generated.
[0025]
  As the electrode material for the hollow plasma generating electrode, and when a pair of plasma generating electrodes are used as the plasma generating means, the electrode material includes Ni, Si, Mo, W, etc. in addition to SUS, Al, etc. Can be adopted. When an electrode material having a large secondary ion emission coefficient due to ion bombardment from the plasma is used, the plasma becomes denser and the processing speed is improved. In particular, in the case of a surface treatment apparatus that performs silicon film formation, when Si is used as an electrode material, the electrode itself functions as a thin film material supply source, so that the film formation speed is improved and Stability is also increased. Furthermore, if boron or phosphorus is doped in advance in an electrode made of Si, doping of the thin film can be performed automatically, which is particularly advantageous when a very small amount of doping is performed.
[0026]
  As the substrate, glass, organic film, or metal such as SUS can be used. Furthermore, the surface treatment apparatus of the present invention can be used for various surface treatments such as film formation, ashing, etching, ion doping, etc., but a silicon thin film or an oxide film such as amorphous silicon or crystalline silicon is formed on the surface of the substrate. When used, it is particularly preferably used.
[0027]
  In the case where a large number of the plasma outlets are provided, it is preferable to generate hollow discharge at all of the outlets because a uniform thin film can be formed on a large area substrate at high speed.
[0028]
  The source gas inlet may be opened in the plasma generation chamber, or only carrier gas is introduced into the plasma generation chamber, and the source gas inlet may be opened on the side of the plasma outlet. it can. Further, for example, by using introduction means such as a pipe for introducing a source gas, the source gas inlet is opened into the substrate processing chamber, and the source gas is introduced between the plasma outlet and the substrate in the substrate processing chamber. May be. When the source gas introduction port is opened at the blowout port or when it is opened in the substrate processing chamber, the source gas is converted into plasma by the plasmaized carrier gas passing through the blowout port. In this case, the inner wall surface of the plasma generation chamber is not contaminated by the source gas.
[0029]
  The plasma generating electrode can be connected to a direct current power source or a high frequency power source and applied from a direct current to a high frequency power, but it is particularly preferable to apply the high frequency power. Furthermore, a bias can be applied to the cathode electrode and the anode electrode by a DC or AC power source or a pulse generating power source, respectively.
[0030]
  In order to generate a hollow discharge at the plasma outlet,Claim 2In the invention according to the present invention, the opening width W (1) of the minimum portion of at least one of the plasma outlets is set to a range satisfying either W (1) ≦ 5L (e) or W (1) ≦ 20X. ing. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X) is the thickness of the sheath layer generated under the desired plasma generation conditions. In addition, the opening width W (1) of the minimum portion of at least one of the plasma outlets satisfies a range satisfying X / 20 ≦ W (1), and further satisfies X / 5 ≦ W (1). It is preferable to set the range.
[0031]
  The mean free path of electrons in the scattering of electrons and gas molecules (including atoms) depends on the gas pressure, the scattering cross section of atoms and molecules, and the temperature. The plasma generation conditions include these gas pressures, Includes scattering cross sections of atoms and molecules, temperature, etc.
[0032]
  By setting the opening width W (1) of the plasma outlet in the above range, hollow discharge can be effectively generated at the plasma outlet and plasma can be efficiently blown out from the outlet. Can do.
[0033]
  In the present invention, the opening width W (1) of the plasma outlet is the diameter when the opening shape of the plasma outlet is circular, and the length of the short side when the shape is rectangular or slit. Dimensions. That is, the shortest dimension in the opening shape is the opening width W (1).
[0034]
  As the shape of the plasma outlet, it is possible to adopt a shape capable of actively drawing the plasma in the plasma generation chamber into the outlet and diffusing the plasma at a desired angle in the substrate processing chamber. For example, a cylindrical shape with a circular cross section, a truncated cone shape that expands from the plasma generation chamber toward the substrate processing chamber, and a combination thereof, and further, a substantially half of the upstream side is reduced in diameter toward the downstream side, and the downstream side Examples include a shape in which the half of the side expands toward the downstream side. Furthermore, as described above, the cross section may be a rectangular column shape or a slit shape.
[0035]
  When surface treatment is performed over a wide area of the substrate, for example, a plurality of circular plasma outlets can be formed in a required pattern. Alternatively, it may be a substantially continuous long slit shape that can be drawn with a single stroke, specifically a spiral shape or a meandering shape.
[0036]
  Claim 3According to the invention, the hollow plasma generating electrode has one or more recesses on the surface facing the plasma generated by the plasma generating means, and at least one of the recesses is a hollow discharge generation region. Yes.
  Also,Claim 4According to the invention, the hollow plasma generating electrode is a hollow body, and the electrode has one or more through holes communicating with the inside of the cavity in a portion facing the plasma generated by the plasma generating means, At least one of the through holes is a hollow discharge generation region.
[0037]
  Thus, a recess is formed in the hollow plasma generating electrode, or a through hole communicating with the hollow plasma generating electrode as a hollow body is formed, and the recess or the through hole is defined as a hollow discharge generation region. By doing so, the surface area of the hollow plasma generating electrode that is substantially in contact with the plasma is increased. For example, when the cathode electrode is a hollow plasma generating electrode and a cathode discharge region is formed on the cathode electrode, the cathode electrode potential (self-bias) at the time of glow discharge generation can be taken in the positive direction, The consumption of input power in the vicinity of the anode electrode, that is, the excitation and decomposition reaction of the raw material gas can be promoted, and the surface treatment speed can be improved.
[0038]
  Such control of the self-bias leads to control of the plasma space potential, and the magnitude of damage caused by the collision of ions with the substrate can be adjusted intentionally. Therefore, for example, when a film forming process is performed, the crystallinity of the crystalline thin film can be controlled.
[0039]
  In order to effectively generate a hollow discharge in the recess or the through hole,Claim 5In the invention according to the above, the opening width W (2) of the minimum portion in the recess or the through hole is set to a range satisfying either W (2) ≦ 5L (e) or W (2) ≦ 20X. Yes. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X) is the thickness of the sheath layer generated under the desired plasma generation conditions.
[0040]
  The cross-sectional shape of the recess or the through hole can be a circle or a polygon, and the shortest dimension in the opening shape is the opening width W (2). Further, the opening width W (2) of the minimum portion of at least one of the plasma outlets satisfies the range satisfying X / 20 ≦ W (2), and further satisfies X / 5 ≦ W (2). It is preferable to set the range.
[0041]
  Claim 6According to the invention, the hollow plasma generating electrode is a hollow body, and the electrode has one or more through holes communicating with the inside of the cavity in a portion facing the plasma generated by the plasma generating means, At least a part of the inside of the cavity is a region where a hollow discharge is generated.
  In this way, by generating hollow discharge in at least a part of the inside of the cavity, the plasma density can be further increased, so that the excitation and decomposition reactions of the source gas are remarkably promoted and the surface treatment speed is improved. Further, when the hollow plasma generating electrode is a cathode electrode, the self-bias can be further controlled to a positive potential by increasing the surface area of the cathode electrode in contact with the plasma. The decomposition reaction is further promoted and the surface treatment speed is significantly improved.
[0042]
  In addition, for an apparatus that performs surface treatment that does not adversely affect the collision of ions with the substrate, such as etching, ashing, or ion doping, the hollow plasma generating electrode is constituted by an anode electrode, and the inner wall surface of the anode electrode is formed. A substrate support may be used, and the inside of the anode electrode may be the substrate processing chamber. In this case, the substrate is directly exposed to the hollow anode discharge, and the processing speed such as etching, ashing, and ion doping is improved. However, such a surface processing apparatus in which the inside of the anode electrode is a substrate processing chamber is not suitable for the film forming process because the ion damage to the substrate is large.
[0043]
  Further, the hollow plasma generating electrode made of a hollow body is preferably provided with one or more partition walls extending in the height direction inside the cavity in order to increase the surface area thereof. That is, it is preferable that the hollow plasma generating electrode has a plurality of cavities defined by the partition walls. In this case, it is necessary to form at least one through hole for each defined region. In order to efficiently generate a hollow discharge inside the cavity of the hollow plasma generating electrode,Claim 7According to the invention, the facing distance H inside the cavity along the through-hole formation direction of the hollow plasma generating electrode is set in a range satisfying either H ≦ 5L (e) or H ≦ 20X. The However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X) is the thickness of the sheath layer generated under the desired plasma generation conditions. The facing distance H inside the cavity along the formation direction of the through hole of the hollow plasma generating electrode that is a hollow body is a range that satisfies X / 20 ≦ H, and also a range that satisfies X / 5 ≦ H. It is preferable to set to.
[0044]
  Also,Claim 8According to the invention, a magnetic field is formed in the vicinity of the plasma outlet and / or in the vicinity of the recess, the through hole, and / or in the cavity.
  Here, “near” includes the inside of the plasma outlet, the recess, and the through hole, and the peripheral edge of the opening, the recess, and the through hole. Further, it is preferable that the magnet be arranged so that the magnetic field lines of the magnetic field are parallel to the axial direction of the plasma outlet, the concave portion, and the through hole, and parallel to the electrode surface inside the cavity.
[0045]
  The strength of the magnetic field is preferably 1 to 2000 mT, more preferably 5 to 500 mT in the plasma outlet, the recess, the center of the through hole, or the inside of the cavity. In addition, the strength of the magnetic field is preferably 2 to 2000 mT, more preferably 5 to 1000 mT at the plasma outlet and / or the recess, the inner wall surface of the through hole and the vicinity thereof, or the vicinity of the cavity inner wall portion. .
[0046]
  By arranging the magnetic field in this way, the trajectory of electrons is adjusted, and in or near the plasma outlet where the hollow discharge occurs, or the recess or the through hole where the hollow cathode discharge or the hollow anode discharge occurs. Thus, electrons can stay in the vicinity and the vicinity thereof, or inside the cavity for a long time, and the generation of active species contributing to the surface treatment is promoted. Therefore, the surface treatment speed is further improved. In addition, since there is no change in the energy of electrons due to this magnetic field, high-quality surface treatment can be maintained without generating ions that have an adverse effect due to the increase in electron energy.
[0047]
  Furthermore,Claim 9According to the invention, there is provided a potential applying means for applying a desired potential to the substrate. For example, the potential application means can apply the same potential to the substrate by applying a desired potential to the substrate support on which the substrate is placed. The same potential applying means includes means for monitoring the potential Vs of the process plasma reaching the substrate and the potential of the substrate, if necessary. The potential Vs of the process plasma is determined by the potential of the electrode with which most of the plasma is in contact. Therefore, for example, the potential Vs of the process plasma can be monitored by monitoring the high-frequency voltage of the plasma generating electrode or the like and the self-bias.
[0048]
  For example, when a film formation process is performed on a substrate, in order to suppress ion damage from plasma, it is desirable to reduce the voltage difference between the substrate and the process plasma potential Vs, which is substantially the same as the plasma potential Vs. It is more preferable to apply this potential. The potential applied to the substrate in the film formation process is preferably in the range of 1/2 to 1 times the potential Vs of the process plasma. For example, in the case of performing an etching treatment, anisotropy can be improved by applying a potential lower than the plasma potential Vs, particularly a negative voltage.
[0049]
  In this way, by applying a desired potential to the substrate and intentionally controlling the voltage difference between the substrate and the plasma, plasma damage can be reduced without reducing the processing speed in the case of film formation. In addition, in the case of an etching process, the etching shape such as anisotropy can be controlled.
[0050]
  Moreover, it is preferable to make a nozzle body project at the opening edge of at least one side of the plasma outlet and / or the recess and the through hole. The nozzle body may have its center line aligned with the axial direction of the plasma outlet and / or the recess and the through hole, or the center line of the nozzle body may be coaxial with the plasma outlet and / or the recess and the through hole. You may arrange | position with an angle with respect to a line direction. The shape of the nozzle body may be a cylinder having a constant cross-sectional shape or a cylinder that gradually decreases or increases the cross-sectional dimension. Furthermore, a tubular nozzle body may be arranged in a spiral shape.
[0051]
  By projecting the nozzle body in the plasma blowout port and / or the recess and through hole, the thickness of the member where the plasma blowout port is formed and the hollow plasma generating electrode may be increased unnecessarily. The length of the plasma outlet and / or recess and through-hole can be freely set, and if the length is increased, the area of occurrence of hollow discharge at the plasma outlet and / or recess and through-hole is expanded. Therefore, the plasma density is increased and the surface treatment speed is improved.
[0052]
  Furthermore, it is preferable that the nozzle length of the nozzle body is indefinite. That is, it is not necessary for all the nozzle bodies to have a uniform length in the plasma outlet and / or the recess, or the plasma outlet and / or the through hole, and the nozzle body can be appropriately changed. Thus, by changing the length of the nozzle body, the intensity of the plasma reaching the substrate can be made uniform over the entire surface of the substrate.
[0053]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings and preferred examples.
  FIG. 1 is a schematic view of a surface treatment apparatus 1 according to a first embodiment of the present invention. The apparatus 1 is shielded from outside air, and a grounded casing 2 is defined in two chambers, a plasma generation chamber 3 and a substrate processing chamber 4.
[0054]
  In the plasma generation chamber 3, a pair of plasma generation electrodes 5 and 6 are arranged vertically in parallel. Of the pair of electrodes 5 and 6, an upper electrode (cathode electrode) 5 connected to the high frequency power source P is attached to an upper wall 2a formed of an insulator of the casing 2, and is grounded. The lower electrode (anode electrode) 6 defines the plasma generation chamber 3 and the substrate processing chamber 4. In addition, although the said anode electrode 6 is attached to the surrounding wall 2b of the casing 2 which is earth | grounded, it is not limited to this, It is possible to attach to the arbitrary positions of the casing 2. FIG.
[0055]
  A circular through hole 7 is formed at the center of the anode electrode 6 and the through hole 7 constitutes the plasma outlet 7 of the present invention. The plasma generation chamber 3 and the substrate processing chamber 4 are communicated with each other through the plasma outlet 7. A partition plate for defining the plasma generation chamber 3 and the substrate processing chamber 4 may be provided separately from the anode electrode 6, and a plasma outlet may be formed in the partition plate.
[0056]
  In the present embodiment, the cross-sectional shape of the plasma outlet 7 is circular, but in addition, for example, a rectangular shape, or a truncated cone shape that expands from the plasma generation chamber 3 toward the substrate processing chamber 4, Further, it is possible to adopt a truncated pyramid shape, or a shape in which a substantially half part on the upstream side is reduced in diameter toward the downstream side and a half part on the downstream side is increased in diameter toward the downstream side. Further, the plasma outlet 7 can be formed into a slit shape.
[0057]
  The opening width W, that is, the diameter W of the plasma outlet 7 is set in a range satisfying either W ≦ 5L (e) or W ≦ 20X. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X) is the thickness of the sheath layer generated under the desired plasma generation conditions. By setting to such a range, the plasma outlet 7 can be set as a generation region of a hollow anode discharge. The opening width W is preferably set in a range of X / 20 ≦ W, and further, the opening width W is preferably set in a range of X / 5 ≦ W.
[0058]
  The upper cathode electrode 5 constitutes a hollow plasma generating electrode of the present invention, and a plurality of concave portions 5a having a circular cross section are formed on the surface of the cathode electrode 5 facing the anode electrode 6. The opening width W of the recess 5a, that is, the diameter W is set in a range satisfying either W ≦ 5L (e) or W ≦ 20X. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X) is the thickness of the sheath layer generated under the desired plasma generation conditions. The opening width W is preferably set in a range of X / 20 ≦ W, and further, the opening width W is preferably set in a range of X / 5 ≦ W. When the gas pressure is in the range of 10 to 1400 Pa among the plasma generation conditions, the diameter of the recess 5a is set in the range of 0.1 to 100 mm, more preferably 1 to 20 mm. By setting the diameter of the concave portion 5a within such a range, the concave portion 5a can be set as a hollow cathode discharge generation region.
[0059]
  The plurality of recesses 5a are32 to 35It is preferable to form in the arrangement as shown in FIG.FIG. 32 (a)An arrangement based on the regular hexagon shown inFIG. 32 (b)An arrangement based on the quadrangle shown in FIG.FIG. 32 (c)The arrangement based on the triangle shown in FIG. Furthermore,33 (a)-(c)As shown in FIG. 5, in these arrangements, an arrangement in which the concave portion 5a is not formed at the central portion, that is, a position immediately above the plasma outlet 7 is more preferable. Also,The radial shape shown in FIGS. 34 (a) and 34 (b), and FIGS. 35 (a) and 35 (b).It is also preferable to arrange it excluding the central portion shown in FIG.
[0060]
  In addition, the length T (thickness direction) dimension T of the plasma outlet 7 and the depth D of the recess 5a generally have a lower limit of X / 50. The upper limit is determined by restrictions on the size of the apparatus, that is, the thickness of the anode electrode 6 or the thickness of the cathode electrode 5. In the case of the gas pressure and diameter described above, the length T of the plasma outlet 7 and the depth D of the recess 5a are preferably 0.1 mm to 100 mm. From the viewpoint of efficiently generating a hollow discharge, it is advantageous that the length T of the plasma outlet 7 and the depth D of the recess 5a are large, and a stronger plasma can be generated. For this reason, a nozzle body is attached to the opening edge of the plasma outlet 7 or the recess 5a to increase the substantial length T of the plasma outlet 7 or the substantial depth D of the recess 5a. it can.
[0061]
  In the present embodiment, the recess 5a has a circular cross section, but may have a polygonal shape. The cross-sectional area may not be constant, and the cross-sectional area may be changed in the axial direction. For example, the bottom surface may be a concave portion larger or smaller than the opening. Furthermore, the concave portion 5a may have a rectangular or groove structure such as a spiral shape or a meandering shape as shown in FIG. In the case of such a rectangular or spiral groove structure, the opening width W of the recess 5a is a groove width (a dimension between groove walls), and the groove width is set within the above-described range. . The groove width may not be constant, and the groove width can be gradually decreased or gradually increased from the center of the cathode electrode 5 toward the outer edge. Moreover, you may form a partial unevenness | corrugation in the inner wall face of the said recessed part 5a. The plurality of recesses 5a do not have to have the same size and form, and a plurality of recesses 5a having different sizes and forms may be formed.
[0062]
  In this embodiment, a gas supply port 8 is formed through the upper wall 2 a of the casing 2 and the cathode electrode 5, and a film forming process is performed from the gas supply port 8 into the plasma generation chamber 3. In some cases, for example, a mixed gas of a source gas such as monosilane and a carrier gas for promoting the generation of plasma and stabilizing the plasma and transporting the source gas to the substrate S is introduced. The gas supply port 8 is not limited to a cylindrical shape, and may be a rectangular tube shape.
[0063]
  Furthermore, the formation position of the gas supply port 8 is not limited to the above position, and can be formed at an arbitrary position. For example, as shown in FIG. 2, it may be formed at a position opening at the bottom of the recess 5 a, or may be formed at a position opening at the peripheral wall of the anode electrode 6. Also, a plurality of the gas supply ports 8 can be formed.
[0064]
  Note that only the carrier gas is introduced into the plasma generation chamber 3 from the gas supply port 8 and the source gas is separately provided with a different introduction port so that the inside of the plasma generation chamber 3, the inside of the film forming chamber 4, or It can also be introduced in the middle of the plasma outlet 7.
[0065]
  A substrate support 9 is disposed in the substrate treatment chamber 4 at a position facing the plasma outlet 7. In this embodiment, since the substrate support 9 is grounded, the substrate S placed on the support 9 is similarly grounded. The substrate support 9, that is, the substrate S, can be biased in a direct or alternating manner without being grounded, or can be biased in a pulse manner. Alternatively, the substrate S can be electrically insulated from the substrate support 9. The substrate support 9 has a built-in heater, and the temperature of the substrate S placed on the upper surface of the substrate support 9 is adjusted to a temperature suitable for vapor phase growth.
  The substrate processing chamber 4 is adjusted to a lower chamber pressure than the plasma generation chamber 3 by a valve, a pressure adjusting valve and a vacuum pump (not shown).
[0066]
  When a high-frequency power is applied to the cathode electrode 5 by a high-frequency power source P when a film forming process is performed by the surface treatment apparatus 1, a discharge occurs between the electrodes 5 and 6, and plasma is generated in the plasma generation chamber 3. To do. The plasma activates the source gas and the carrier gas introduced into the plasma generation chamber 3, and generates active species that contribute to film formation. At this time, since the substrate processing chamber 4 adjusts the chamber pressure to be lower than that of the plasma generation chamber 3, the plasma in the plasma generation chamber 3 is generated by the differential pressure and further diffusion. 7 flows out into the substrate processing chamber 4. The surface of the substrate S in the processing chamber 4 is plasma-processed by this plasma flow, and a thin film is formed on the surface of the substrate 4.
[0067]
  At this time, the cathode electrode 5 is formed with a plurality of recesses 5a, and the opening width W of the recesses 5a is set within the above-described range, so that a normal glow discharge is performed according to the applied high frequency power. To discharge including hollow cathode discharge. Hollow cathode discharge is generated in the recess 5a, and new plasma is generated in the recess 5a. For this reason, the plasma generated in the plasma generation chamber 3 becomes a high-density plasma, and the number of active species contributing to the film formation process increases, so that the surface treatment speed is increased. Further, by forming the concave portion 5a in the cathode electrode 5, the surface area of the cathode electrode 5 that is substantially in contact with plasma is increased. As a result, the self-bias at the time of discharge generation can be taken in a more positive direction, the excitation and decomposition reaction of the source gas in the vicinity of the grounded anode electrode 6 is promoted, and the surface treatment speed is improved. be able to.
[0068]
  Furthermore, by setting the opening width W of the plasma outlet 7 within the above range, a hollow anode discharge is generated at the plasma outlet 7. Since the plasma is newly generated at the plasma outlet 7 by this hollow anode discharge, the density of the plasma guided to the substrate processing chamber 4 is increased. Furthermore, when the plasma generated in the plasma generation chamber 3 passes through the plasma outlet 7 which is the generation region of the hollow anode discharge, the energy of electrons in the plasma is sufficient to generate active species, Since it is moderately reduced to an intensity insufficient to generate ions, the active species contributing to the film formation further increase in the plasma guided to the substrate processing chamber 4, resulting in a plasma with a high density, and the film formation speed is increased. Remarkably improved. Furthermore, since the ion energy in the plasma also decreases when passing through the plasma outlet 7 where hollow anode discharge is generated, the plasma guided to the substrate processing chamber 4 collides with the substrate. There are few ions that cause damage, and high-quality film formation is possible.
[0069]
  Furthermore, in addition to the hollow anode discharge at the plasma outlet 7, the hollow cathode discharge is generated, so that the electron temperature of the plasma between the electrodes 5 and 6 is lowered and the electron density is increased. Will improve. Furthermore, since the high frequency voltage at the cathode electrode 5 decreases and the self-bias voltage increases due to the hollow cathode discharge, the space potential of the plasma generated between the electrodes 5 and 6 also increases. As a result, a hollow anode discharge is likely to occur at the plasma outlet 7, and a synergistic effect can be obtained that high-density plasma can be generated at the plasma outlet 7. For the same reason, electric field concentration is likely to occur in the plasma generation chamber 3, and non-uniform discharge that has been made into high-density plasma locally can be generated.
[0070]
  As described above, in the present embodiment, the substrate support 9, that is, the substrate S is grounded. However, a desired potential can be applied without grounding the substrate S. In the film formation process, a potential that is 1/2 to 1 times the potential Vs of the process plasma that reaches the substrate S is applied to the substrate S to reduce the voltage difference between the substrate and the process plasma. It is possible to form a high-quality thin film by reducing ion damage from plasma.
[0071]
  At this time, the potential Vs of the process plasma is determined by the potential of the electrode with which most of the plasma is in contact. Therefore, for example, the potential Vs of the process plasma can be monitored by monitoring a high-frequency voltage such as a cathode electrode and a self-bias.
[0072]
  Furthermore, in the present embodiment, a single plasma outlet 7 having a circular cross section is formed. However, when the surface treatment is performed over a large area of the substrate S, the plasma outlet 7 is, for example,32-35A plurality of them can be formed in the arrangement as shown in FIG. Furthermore, a substantially continuous slit shape that can be drawn with one stroke, for example,FIG.If a shape such as a spiral shape or a meandering shape is used, uniform processing over a large area is possible.
[0073]
  In addition, it is preferable to set the hole diameter and the slit width W within the scope of the present invention, both in the case of a plurality of holes and in the shape of a slit. However, the plurality of holes do not need to have a constant hole diameter, and the slit width does not need to be constant in the length direction. In order to generate a hollow anode discharge uniformly, it is desirable to gradually reduce or gradually increase the size of the hole diameter and the slit width from the central portion of the anode electrode to the outer edge portion according to various conditions.
[0074]
  In the above embodiment, the anode electrode 6 is grounded. However, a bias can be applied to the electrodes 5 and 6 by a DC or AC power source or a pulse power source, respectively. Further, in the above-described embodiment, the plasma generation chamber 3 and the substrate processing chamber 4 are defined by the anode electrode 6, but the partition plate having a plasma outlet is provided separately from the anode electrode 6 to generate plasma. The chamber 3 and the substrate processing chamber 4 can also be defined.
[0075]
  In this embodiment, the internal gas is exhausted from the substrate processing chamber 4, and the substrate processing chamber 4 is adjusted to a lower chamber pressure than the plasma generation chamber 3. Therefore, although the internal gas flow from the plasma generation chamber 3 to the substrate processing chamber 4 is formed in the surface processing apparatus, the present invention is not limited to this. An internal gas exhaust port may be provided in the plasma generation chamber to reverse the flow of the internal gas. However, in this case, since the plasma is transported from the plasma generation chamber 3 to the substrate processing chamber 4 only by diffusion and plasma transport due to the flow of the internal gas cannot be expected, the surface treatment speed is slightly reduced. As a result, high-speed processing is ensured.
[0076]
  Furthermore, even when other surface treatments such as ashing, etching, ion doping and the like are performed using the above-described apparatus, the surface treatment can be performed at a lower temperature and at a higher speed than in the past. For example, when an etching process is performed, anisotropy can be improved by applying a potential lower than the potential Vs of the process plasma, particularly a negative voltage, to the substrate S.
[0077]
  Hereinafter, another embodiment of the present invention will be specifically described with reference to the drawings. In the following description, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0078]
  FIG. 3 is a schematic view of the surface treatment apparatus 20 according to the second embodiment. The apparatus 20 differs from the first embodiment described above in that the magnet 10 is disposed on the inner wall surface of the recess 5a formed in the cathode electrode 5 and the inner wall surface of the plasma outlet 7, but the other configurations are the same as described above. This is the same as the surface treatment apparatus 1 of the first embodiment. The magnet 10 only needs to be arranged so as to apply a magnetic field to the recess 5a and the plasma outlet 7. Therefore, in addition to embedding the magnet 10 in the inner wall surface as shown in FIG. 3, for example, as shown in FIG. 4 (a), the magnet 10 is embedded above the recess 5a in the cathode electrode 5. Alternatively, as shown in FIG. 4B, it can be arranged outside the cathode electrode 5, or a combination of these arrangements. In arranging these magnets 10, it is preferable to attach the magnets 10 so that the magnets 10 are not directly exposed to plasma.
[0079]
  It is preferable that the magnetic field of the magnet 10 is applied so that the direction of the lines of magnetic force is parallel to the respective axial directions of the concave portion 5 a and the plasma outlet 7. The strength of the magnet is 1 to 2000 mT at the axial center of the recess 5a and the plasma outlet 7, and 2 to 2000 mT at the inner wall surface and the vicinity thereof, more preferably 5 to 500 mT at the axial center and at the inner wall surface and the vicinity thereof. 5 to 1000 mT.
[0080]
  Thus, by forming a magnetic field in the recess 5a and the plasma outlet 7, the trajectory of electrons generated in the plasma is adjusted by the magnetic field, and the electrons are elongated in the recess and the plasma outlet 7. Can stay. By adjusting the electron trajectory, the action time of the electrons on the source gas can be extended without increasing the electron energy (electron temperature), so that the generation of active species is promoted and the film formation rate is improved.
[0081]
  Further, when the magnet 10 is arranged to form a magnetic field, the allowable range of the dimension of the opening width W or depth D of the recess 5a or the opening width W of the plasma outlet 7 is not provided with the magnet 10. Compared to about 30%.
[0082]
  In this embodiment, the magnets 10 are arranged in all the recesses 5a and the plasma outlets 7, but the magnets 10 are arranged only in selected ones instead of the magnets 10 in all of them. You can also. Furthermore, it is possible to form a magnetic field by means such as an electromagnet. Further, the arrangement of the magnetic field including the polarity of the magnet and the intensity of the magnetic field are arbitrarily set so as to increase the plasma density.
[0083]
  FIG. 5 is a schematic view of a surface treatment apparatus 21 according to the third embodiment. The apparatus 21 is different from the first embodiment described above in that the cathode electrode 11 which is the hollow plasma generating electrode of the present invention is a hollow cylindrical hollow body, but the other configuration is the surface treatment of the first embodiment. Same as device 1.
[0084]
  The cathode electrode 11, which is a hollow body, has a plurality of through-holes 11 b having a circular cross section communicating with the inside of the cavity in a portion facing the anode electrode 6, that is, the lower wall portion 11 a of the cathode electrode 11. This through hole 11b32-35It is preferable to form in the arrangement as shown in FIG. The through hole 11b is located at a position avoiding the position directly above the plasma outlet 7 formed in the anode electrode 6, that is,33 or 35It is more desirable to form in the arrangement shown in FIG.
[0085]
  The opening width W, that is, the diameter W, is set in a range satisfying either W ≦ 5L (e) or W ≦ 20X so that the through hole 11b can be a hollow cathode discharge generation region. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X is the thickness of the sheath layer generated under the desired plasma generation conditions. The opening width W is preferably set in a range of X / 20 ≦ W, and more preferably in a range of X / 5 ≦ W.
[0086]
  In addition, the plurality of through holes 11b may not have the same opening width W, and different opening widths W may be appropriately set in order to uniformly generate hollow cathode discharge in the plurality of through holes 11b. it can. In particular, the through-hole 11b near the center decreases the opening width W and gradually increases the opening width W in the outer edge direction according to the frequency of the applied power or according to other conditions, or increases the opening width W near the center. It is preferable that the opening width W be gradually increased in the outer edge direction.
[0087]
  When the gas pressure is in the range of 10 to 1400 Pa among the plasma generation conditions, the diameter of the through hole 11b is set in the range of 0.1 to 100 mm, more preferably 1 to 20 mm. By setting the diameter of the through hole 11b within such a range, a hollow cathode discharge is generated in the through hole 11b.
[0088]
  Further, the length T of the through hole 11b, that is, in the case of the present embodiment, the thickness T of the lower wall portion 11a has a lower limit of about X / 50. The upper limit is determined by device size constraints. The length T of the through hole 11b is preferably 0.3 to 70 mm in the case of the gas pressure and diameter described above.
[0089]
  In the present embodiment, the through hole 11b has a circular cross section, but may have any other shape such as an ellipse, a rectangle, a polygon, and an indefinite shape. The cross-sectional area may not be constant, and the cross-sectional area may be changed in the axial direction. Furthermore, the through-hole 11b may have a slit structure having a rectangular cross section, or a slit structure having a one-dimensional extension such as a spiral shape or a meandering shape as shown in FIG. In the case of such a slit structure, the opening width W of the through-hole 11b is the slit width, and this slit width is set within the above range. The slit width does not have to be constant, and can be gradually increased or decreased from the center toward the outer edge. Moreover, you may form a partial unevenness | corrugation in the inner wall face of the said through-hole 11b. The plurality of through-holes 11b do not have to have the same size and the same form, and a plurality of through-holes 11b having different sizes and forms may be formed.
[0090]
  Furthermore, in this embodiment, the facing distance inside the cavity along the direction of formation of the through hole 11b of the cathode electrode 11, that is, the inside of the cavity of the cathode electrode 11 can be used as a generation region of a hollow cathode discharge, that is, In the drawing, the vertical height H is set in a range satisfying either H ≦ 5L (e) or H ≦ 20X. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X is the thickness of the sheath layer generated under the desired plasma generation conditions. The height H inside the cavity is preferably set in the range of X / 20 ≦ H, and more preferably in the range of X / 5 ≦ H. When the gas pressure is within the range of 10 to 1400 Pa as described above and the dimension of the through hole 11b is within the above range, the height H inside the cavity is 0.1 to 100 mm. Preferably, the height H inside the cavity is more preferably set to 1 to 20 mm.
[0091]
  In the illustrated example, the height H inside the cavity is constant, but the height H may not be constant. In order to generate a hollow cathode discharge uniformly over almost the entire area inside the cavity, the height H inside the cavity near the center is reduced according to the frequency of the applied power or according to other conditions, and the height in the outer edge direction is increased. It is preferable to gradually increase the height H, or to increase the height H near the center and gradually decrease the height H in the outer edge direction.
[0092]
  Further, in the illustrated example, the cathode electrode 11 is a hollow body having a substantially uniform wall portion and hollow as a whole. However, the peripheral wall portion is thickened so that only the central portion is hollow or a local portion is formed. A typical hollow part can also be formed. Moreover, a recessed part can also be formed in the hollow part.
[0093]
  A cylindrical gas supply port 11d is formed in the center of the upper wall portion 11c of the cathode electrode 11, and a source gas such as monosilane and plasma are promoted from the gas supply port 11d into the cavity of the cathode electrode 11. In addition, a mixed gas with a carrier gas for stabilizing the plasma and conveying the source gas to the substrate S is introduced. The gas supply port 11d is not limited to a cylindrical shape, and may be a rectangular cylindrical shape. Furthermore, the formation position of the gas supply port 11d is not limited to the center of the upper wall portion 11c, and can be formed at an arbitrary position.
[0094]
  The mixed gas introduced into the cathode electrode 11 from the gas supply port 11d is introduced into the plasma generation chamber 3 from the through hole 11b in a shower shape. As described above, the mixed gas is once stored in the cathode electrode 11 and then introduced into the plasma generation chamber 3 in the form of a shower from the through-hole 11b, so that the mixed gas has a uniform concentration and pressure. It can be introduced into the plasma generation chamber 3.
[0095]
  It should be noted that only the carrier gas is introduced into the cavity of the cathode electrode 11, and the source gas is provided with a different inlet, so that the inside of the plasma generation chamber 3, the inside of the film forming chamber 4, or the plasma outlet 7 can also be introduced.
[0096]
  When high frequency power is applied to the cathode electrode 11 by a high frequency power source P, a discharge occurs between the electrodes 11 and 6, and plasma is generated in the plasma generation chamber 3.
  A transition from normal glow discharge to discharge including hollow cathode discharge is made according to the applied high frequency power. At this time, the cathode electrode 11 generates a hollow cathode discharge in the through hole 11 b, generates a new plasma in the through hole 11 b, and also generates a hollow cathode discharge in the cavity of the cathode electrode 11. New plasma is generated. For this reason, the plasma generated in the plasma generation chamber 3 becomes a high-density plasma, and the number of active species contributing to the film formation process increases, so that the surface treatment speed is increased.
[0097]
  Further, since the cathode electrode 11 is a hollow body and a through hole 11b is formed to generate plasma in the through hole 11b and the inside of the cavity, the surface area of the cathode electrode 11 substantially in contact with the plasma is It further increases compared with the case of the first embodiment described above. As a result, the self-bias at the time of discharge generation can be brought to the positive side, the excitation and decomposition reaction of the source gas in the vicinity of the grounded anode electrode 6 is promoted, and the surface treatment speed is further improved. Can be made.
[0098]
  <Experiment 1>
  In the surface treatment apparatus 21 according to the third embodiment, the diameter of the through hole 11b of the cathode electrode 11 is 2 to 20 mm, the length dimension T of the through hole 11b is 2 to 8 mm, and the height H inside the cavity is 2 to 20 mm. Set, hydrogen gas pressure is 133 Pa, RF power with frequency 13.56 MHz is 0.02 W / cm²Applied. As a result, a hollow anode discharge occurred at the plasma outlet 7, and a hollow cathode discharge occurred inside the through hole 11b of the cathode electrode 11 and inside the cavity.
[0099]
  Furthermore, the self-bias of the cathode electrode 11 at this time was −9 V even at the lowest value. On the other hand, when the diameter of the through-hole 11b of the cathode electrode 11 is 1 mm and the hollow cathode discharge is not generated inside the through-hole 11b and the cavity, the normal normal discharge type has the same gas pressure and RF power. The self-bias of the cathode electrode is -30V, and in the case of a normal parallel plate type, the self-bias is -74V. From this, it can be seen that in the surface treatment apparatus 21 of the above-described embodiment, the self-bias of the cathode electrode 11 is significantly shifted to the positive side. It is also possible to change the polarity of the self-bias to a positive potential depending on the conditions.
[0100]
  Further, under the above conditions, when the length dimension T of the through hole 11b of the cathode electrode 11 is 9 mm, no hollow cathode discharge occurs in the through hole 11b, and the hollow cathode discharge also occurs inside the cavity of the cathode electrode 11. Did not occur. Therefore, when the RF power is increased with the length T of the through hole 11b being 9 mm, 0.05 W / cm.²At this time, hollow cathode discharge occurred in the through hole 11b of the cathode electrode 11 and inside the cavity.
[0101]
  Furthermore, when the diameter of the through hole 11b of the cathode electrode 11 is 5 mm and the height H inside the cavity of the cathode electrode 11 is 2 mm, the RF power is 0.02 W / cm.²In the following, hollow cathode discharge did not occur inside the cavity, but the self-bias of the cathode electrode 11 was as large as -6V and was closer to the positive side. When the height H is 9 mm, the RF power is 0.05 W / cm.²In the following, no hollow cathode discharge occurred inside the cavity, but in this case as well, the self-bias of the cathode electrode 11 is −9 V, which is a higher voltage than the above-mentioned regular discharge type and normal parallel plate type. It was.
[0102]
  <Experiment 2>
  Using the surface treatment device 21, monosilane gas (SiH) is used as a raw material gas._Four) 7 cm^Three/ Min. At a flow rate of 105 cm hydrogen gas as carrier gas^Three/ Min., And the pressure in the film formation chamber is adjusted to 29 Pa and the substrate temperature is adjusted to 150 to 260 ° C. to obtain 13.56 MHz and 0.1 W / cm.²A high frequency power was applied to form a film on a white glass substrate. As a result, even when the substrate temperature was as low as 150 ° C., a microcrystalline thin film was formed on the substrate surface. Further, in the above temperature range, the maximum deposition rate of the microcrystalline thin film was 40 liters / sec., And it was possible to deposit at a high speed that could not be achieved in the past. Further, by optimizing the above film formation conditions and setting the substrate temperature to 300 ° C., it becomes possible to form a film at an extremely high speed of 150 Å / sec. With such high speed film formation, the thin film is microcrystallized. Thus, the thin film functioned sufficiently as a solar cell. Of course, when an amorphous thin film is formed, the film can be formed at a higher speed.
[0103]
  <Experiment 3>
  When the frequency of the high-frequency power source P is set to 105 MHz using the surface treatment apparatus 21, the pressure of the substrate processing chamber 3 is set to 10 to 1400 Pa, and the temperature of the substrate is set to a range of 100 to 450 ° C., it is a carrier gas. Hydrogen gas flow rate and monosilane gas (SiH)_Four), The hydrogen gas flow rate / the monosilane gas flow rate is R, and a crystalline silicon thin film that is not amorphous can be produced within the range of 0.5 <R. Moreover, when a solar cell having a p-i-n structure was prototyped, it was confirmed that the solar cell operated as a solar cell.
[0104]
  In particular, when it is in the range of 0.5 <R <20, it was conventionally said that crystallization is difficult, but the R is large, that is, equal to or higher than that when the hydrogen gas flow rate is large relative to the monosilane gas flow rate. It was confirmed by X-ray diffraction and Raman spectroscopy that a good crystalline thin film was obtained.
  Table 1 below illustrates specific processing conditions and film formation speeds at which a crystalline thin film can be formed under the conditions.
[Table 1]

  It was confirmed that all the crystalline thin films of Samples 1 to 4 described above were crystalline thin films oriented to (220) by X-ray diffraction.
  Furthermore, when these thin films are applied to p-i-n type solar cells, after laminating with n-type and i-type (the above conditions), the power is lower than the above conditions before p-type is laminated. The efficiency of the solar cell is improved by laminating the i-type layer at a lower speed and then forming the p-type layer to form a battery. For example, 80 Pa, 100 to 450 ° C., H₂; 40 sccm, SiH_Four1.5 sccm, RF power; 0.25 W / cm²When the i-layer having a thickness of 5 to 100 nm was inserted as the buffer layer under the above conditions and the film formation rate of 0.01 μm / min, the efficiency of the solar cell was improved by 50%.
[0105]
  The reason why the film formation speed was improved in this way was that a high-density plasma was first obtained by the hollow anode discharge at the plasma outlet 7, the through-hole 11 b of the cathode electrode 11 and the hollow cathode discharge inside the cavity. Is mentioned. Further, by increasing the surface area of the cathode electrode 11 in contact with the plasma, the self-bias can be brought to the positive side, and the plasma is generated even in a region close to the anode electrode. Plasma can be efficiently guided to the substrate surface through the plasma outlet 7. In addition, this self-bias control makes it possible to control the plasma space potential at the same time, so that the plasma space potential can be set appropriately and an appropriate ion bombardment can be applied according to the deposition rate. It is considered that crystallization at high speed film formation has become possible.
[0106]
  Note that the above-described surface treatment apparatus 21 can perform surface treatment at a lower temperature and higher speed than in the past even when other surface treatments such as ashing, etching, and ion doping other than film formation are performed. It was.
[0107]
  FIG. 6 is a schematic view of a surface treatment apparatus 22 according to the fourth embodiment. The apparatus 22 is different from the third embodiment described above in that the magnet 10 is arranged on the inner wall surface of the through hole 11b formed in the cathode electrode 11 which is a hollow body and the inner wall surface of the plasma outlet 7. Other configurations are the same as those of the surface treatment apparatus 21 of the third embodiment.
[0108]
  The magnetic field of the magnet 10 is preferably applied so that the direction of the magnetic lines of force is parallel to the respective axial directions of the through hole 11b and the plasma outlet 7. The strength of the magnet is 1 to 2000 mT at the axial center of the through hole 11b and the plasma outlet 7 and 2 to 2000 mT at the inner wall surface and its vicinity, more preferably 5 to 500 mT at the axial center and the inner wall surface and its vicinity. 5 to 1000 mT.
[0109]
  By forming a magnetic field in the through hole 11b and the plasma outlet 7 in this way, the trajectory of electrons in the plasma generated therein is adjusted by the magnetic field, and the inside of the through hole 11b and the plasma outlet 7 is adjusted. Electrons can stay for a long time. By adjusting the electron trajectory, the action time of the electrons on the source gas can be extended without increasing the electron energy (electron temperature), so that the generation of active species is promoted and the film formation rate is improved.
[0110]
  Further, when the magnet 10 is arranged to form a magnetic field, the allowable ranges of the dimensions of the opening width W and length T of the through hole 11b and the opening width W of the plasma outlet 7 are not arranged. Compared to, it spreads about 30%.
[0111]
  In this embodiment, the magnets 10 are arranged in all the through holes 11b and the plasma outlets 7, but the magnets 10 are arranged only in any one selected instead of arranging the magnets 10 in all of them. You can also. It is also possible to form a magnetic field by means such as an electromagnet. Furthermore, the magnet 10 can be embedded in the inner wall surface of the through hole 11b and the plasma outlet 7, for example. Alternatively, it is embedded in the upper wall portion 11c of the cathode electrode 11 which is a hollow body as shown in FIG. 7 (a), or as shown in FIG. 7 (b). It can also be arranged above. The arrangement including the polarity of the magnet 10 and the strength of the magnetic field are arbitrarily set so as to increase the plasma density.
[0112]
  It is also possible to arrange magnets to form a magnetic field inside the cavity so that the hollow cathode discharge inside the cavity has a higher density. In this case, it is desirable to apply a magnetic field so that the magnetic field lines inside the cavity are parallel to the electrode surface. For example, as shown in FIG. 8 (a), the cathode electrode 11 is arranged inside the upper and lower walls 11c, 11a or outside the peripheral wall of the cathode electrode 11, or as shown in FIG. 8 (b). You may distribute | arrange to the outer side of the electrode 11, the upper part of the upper wall part 11c, the inside of the lower wall part 11a of the cathode electrode, the outer side of a surrounding wall part, etc. Moreover, as shown in FIG.8 (c), it can also be embed | buried inside a surrounding wall part. FIG. 8C shows various arrangements collectively in one figure.
[0113]
  These drawings are merely examples of the arrangement of the magnets, and are not limited to the arrangement position and number of the magnets 10 disclosed in these drawings. The magnet 10 is embedded in the cathode electrode 11 or arranged outside, or a combination of the magnet 10 and the magnetic field strength so that the hollow cathode discharge in the cavity or the through hole 11b has a higher density. It can be set arbitrarily. In arranging these magnets 10, it is preferable to attach the magnets 10 so that they are not directly exposed to plasma.
[0114]
  <Experiment 4>
  Using the surface treatment apparatus 22 according to the fourth embodiment shown in FIG. 6, the same conditions as in Experiment 2 of the third embodiment described above, that is, monosilane gas (SiH_Four) 7cm^Three/ Min. At a flow rate of 105 cm.^Three/ Min. In addition, the pressure in the film formation chamber is adjusted to 29 Pa, and the substrate temperature is adjusted to 150 to 260 ° C. to obtain 13.56 MHz, 0.1 W / cm.²A high frequency power was applied to form a film on a white glass substrate. As a result, the film formation rate was 70 cm / sec. Compared to the case of the third embodiment, the film can be formed at a speed as high as 75%, and the thin film is microcrystallized and functions sufficiently as a solar cell. Met.
[0115]
  Further, FIG. 9 shows a modification in which the plasma density generated by the hollow cathode discharge in the through-hole 11b or the cavity in the cathode electrode 11 is increased.
  First, from the viewpoint of efficiently generating a hollow cathode discharge in the through hole 11b, it is advantageous that the length T of the through hole 11b is large, and a stronger plasma can be generated. However, the thickness of the lower wall portion 11a of the cathode electrode is desirably a minimum thickness that can withstand the gas pressure and applied power introduced into the cavity from the viewpoint of material cost.
[0116]
  Therefore, in order to increase the length T of the through hole 11b, it is desirable to attach the nozzle body 12 to the periphery of the through hole 11b. The nozzle body 12 may project from the through hole 11b toward the plasma generation chamber 3 or project into the cavity. Furthermore, you may project on both sides. Moreover, the nozzle body 12 can also be comprised with the magnet 10, as shown in FIG. However, it is preferable that the magnet 10 is not directly exposed to plasma.
[0117]
  In addition, although all the nozzle bodies 12 shown in FIG. 9 are arranged with their center lines aligned with the lines of the through holes 11b, the center lines of the nozzle bodies 12 are angled with respect to the axes of the through holes 11b. In other words, the nozzle body 12 can be arranged obliquely. The nozzle body 12 shown in FIG. 9 is a cylindrical body having a constant cross-sectional area, but is not limited to such a shape, and may be a cylindrical body having a shape that gradually increases or decreases its cross-sectional area. Furthermore, a tubular nozzle body can be arranged in a spiral shape.
  Such deformation of the nozzle body can also be applied to the nozzle body attached to the above-described plasma outlet and recess.
[0118]
  Furthermore, in order to increase the surface area of the cathode electrode 11 in contact with the plasma, the inside of the cavity of the cathode electrode 11 can be partitioned by a partition wall 11e extending in the height direction. Thus, since the surface area can be freely adjusted, the self-bias of the cathode electrode 11 can be freely controlled. The partition wall 11e may not be in close contact with the upper and lower wall portions 11c and 11a of the cathode electrode 11, and the partitioned spaces may be communicated with each other.
[0119]
  It is desirable to provide a gas supply port 11d in each partitioned space as shown in FIG. Alternatively, the gas supply port 8 can be formed at a position opening in the peripheral wall portion of the anode electrode 6, or a plurality of the gas supply ports 8 and 11d can be formed in combination. Only the carrier gas is introduced from the gas supply port 11d of the cathode electrode 11, and the source gas is provided inside the plasma generation chamber 3 by providing a gas supply port 8 of the anode electrode 6 or a different introduction port separately. It can also be introduced into the film forming chamber 4 or in the middle of the plasma outlet 7.
[0120]
  9 illustrates the form of the plurality of through holes 11b, and is not limited to the illustrated embodiment in which all the through holes 11b have different forms. All the through holes 11b may have the same form, or a plurality of types of through holes 11b may be mixed. The length of the nozzle body 12 may be the same in all the through-holes 11b, or the length may be changed as appropriate so that the plasma intensity reaching the substrate surface is made uniform over the entire surface of the substrate. You can also. Further, the formation position and the number of the partition walls are not limited to those shown in FIG. 9 and can be freely designed according to the strength of plasma necessary for the surface treatment.
[0121]
  Furthermore, it is known that crystallization progresses when the high frequency excitation power supply frequency is increased as a factor that influences the strength of plasma. Therefore, an experiment was conducted to change the frequency.
  <Experiment 5>
  In Experiments 1, 2, and 4 described above, the high-frequency excitation power supply frequency was 13.56 MHz, but this was changed to 105 MHz and film formation was performed under the same conditions. The thin film was crystallized even when the film formation rate was 260 Å / sec. Further, when the film formation rate was 240 Å / sec., A crystal film that could function sufficiently as a solar cell was obtained.
[0122]
  In the above-described third and fourth embodiments and their modifications in which the cathode electrode 11 is a hollow body, hollow cathode discharge is generated in almost the entire area inside the cavity of the cathode electrode 11, as shown in FIGS. is doing. However, depending on the height inside the cavity of the cathode electrode 11 and the shape, number, and arrangement of the through-holes 11d, and the arrangement of the magnet 10, the hollow discharge may not occur over the entire area inside the cavity. A hollow cathode discharge may occur only in a part of the cavity, or a hollow cathode discharge may occur nonuniformly in the cavity. As a general tendency, a hollow discharge that is brighter than the others is generated in the hollow portion in the vicinity of the through-hole in which the hollow discharge occurs.
[0123]
  FIG. 11 is a schematic view of a surface treatment apparatus 23 according to the fifth embodiment. The device 23 is different from the third embodiment described above in that the inner wall surface inside the cavity is made of an insulator so that the hollow cathode discharge does not occur inside the cathode electrode 11 '. The configuration is the same as the surface treatment apparatus 21 of the third embodiment.
[0124]
  However, a part of the electrode may be exposed on the inner surface of the lower wall portion 11a of the cathode electrode 11 '. In this case, the plasma generated in the plasma generation chamber 3 enters the cavity through the through hole 11b. The exposed electrode surface can be scratched. As a result, the surface area of the cathode electrode 11 ′ to which the plasma can substantially contact can be increased, and the self-bias can be increased.
[0125]
  Further, in order to prevent the hollow cathode discharge from being generated inside the cavity of the cathode electrode 11 ', in addition to the construction of the inner wall surface as described above, the method of increasing the height H inside the cavity However, since this height H also changes depending on the RF power and gas pressure, a method of configuring the inner wall surface with an insulator is more reliable.
[0126]
  In this way, the plasma generation location can be controlled, the surface area of the cathode electrode 11 ′ contacting the plasma can be adjusted, and the self-bias can be controlled, so that plasma having a strength suitable for the application can be generated.
[0127]
  <Experiment 6>
  When the surface treatment apparatus 23 was used to form a film under the same conditions as in Experiment 2 described above, a hollow cathode discharge occurred in the through hole 11b, and a hollow anode discharge occurred in the plasma outlet 7. As a result, the density of plasma was increased, and a microcrystalline thin film could be formed at a high speed. Further, the obtained thin film could function sufficiently as a solar cell.
[0128]
  FIG. 12 is a schematic view of a surface treatment device 24 according to the sixth embodiment. This surface treatment device 24 is used for the through holes 11b of the cathode electrode 11 ′ and the plasma outlet 7 in the surface treatment device 23 of the fifth embodiment described above. The magnet 10 is arranged on the inner peripheral wall.
[0129]
  <Experiment 7>
  When the film was formed under the same conditions as in Experiment 2 using the surface treatment apparatus 24 of the sixth example, the film formation rate and battery efficiency were improved by 10% or more compared to Experiment 6 described above. did.
[0130]
  As a modification of the cathode electrode 11 that is the above-described hollow body, for example, a lower wall portion having a plurality of through holes 15b that communicate with the inside of the cavity, such as the cathode electrode 15 that is the hollow body shown in FIG. The space between 15a and the upper wall portion 15c can be divided into a plurality of stages in the vertical direction by one or more partition walls 15e having one or more through holes 15d. At this time, a plurality of through-holes 15b formed in the lower wall portion 15a and a plurality of through-holes formed in the partition wall 15e as in the cathode electrode 15 'which is a hollow body shown in FIG. 13B. It is preferable to form the respective through holes 15b and 15d so that 15d does not overlap with each other in the vertical direction.
[0131]
  Further, the number of the through holes 15b and 15d may be different between the lower wall portion 15a and the partition wall 15e. Moreover, the opening dimension of each through-hole 15b, 15d may also differ in the lower wall part 15a and the partition wall 15e, Furthermore, several penetration hole 15b of the lower wall part 15a and several penetration of the partition wall 15e are sufficient. Also in the holes 15d, it is not necessary to make all the openings uniformly uniform, and the openings can be changed so as to gradually decrease or gradually increase from the central portion toward the outer edge.
[0132]
  As still another modified example of the cathode electrode 11 which is the above-described hollow body, a plurality of hollow electrode members 16a are vertically arranged in a plurality of stages by connecting ports 16b as in the cathode electrode 16 having a hollow body shown in FIG. It can also be connected to.
[0133]
  FIG. 14 is a schematic view of a surface treatment apparatus 25 according to a seventh embodiment of the present invention. In the surface treatment apparatus 25, the casing 2 is divided into two chambers, a plasma generation chamber 3 and a substrate processing chamber 4. A cathode electrode 5 and an anode electrode 6 ′ are disposed in the plasma generation chamber 3, and the anode electrode 6 ′ defines the plasma generation chamber 3 and the substrate processing chamber 4. A circular plasma outlet 7 'is formed at the center of the anode electrode 6', and the plasma generation chamber 3 and the substrate processing chamber 4 are communicated with each other through the plasma outlet 7 '.
[0134]
  The cathode electrode 5 is formed with a plurality of concave portions 5a having a circular cross section on the surface facing the anode electrode 6 '. The opening width W of the concave portions 5a is W ≦ 5L (e) or W ≦ 20X. Is set in a range that satisfies either of the above. More preferably, the opening width W is set in a range of X / 5 ≦ W. By setting the diameter of the recess 5a within such a range, a hollow cathode discharge is generated in the recess 5a.
[0135]
  The above configuration of the present embodiment is the same as that of the first embodiment described above, but the opening width W of the plasma outlet 7 'formed in the anode electrode 6' is large, or the length (thickness) T. Therefore, it is different from the surface treatment apparatus 1 of the first embodiment described above in that no hollow discharge is generated at the plasma outlet 7 ′.
[0136]
  In this embodiment, since no hollow discharge is generated at the plasma outlet 7 ', the surface treatment speed and quality are slightly inferior to those of the first embodiment described above, but the hollow cathode discharge is generated in the recess 5a of the cathode electrode 5. Therefore, the processing speed and processing quality are improved as compared with the conventional surface processing apparatus.
[0137]
  In any of the above-described embodiments, the plasma generation chamber 3 is provided above the surface treatment apparatus and the substrate processing chamber 4 is provided below the surface treatment apparatus. On the contrary, the plasma generation chamber 3 is disposed below. In addition, a substrate processing chamber may be provided above the apparatus so that plasma flows out from below to above. Furthermore, the casing of the surface processing apparatus may be defined as two chambers on the left and right sides, and the plasma generation chamber and the substrate processing chamber may be horizontally disposed so that the plasma flows out in the lateral direction. In either case, the substrate can be disposed so as to face the plasma outlet and orthogonal to the plasma outflow direction, or the substrate can be disposed in parallel with the plasma outflow direction. The plasma generating means is not limited to a pair of plasma generating electrodes. For example, discharge having three or more electrodes, microwave discharge, capacitively coupled discharge, inductively coupled discharge, PIG discharge, electron beam excited discharge. It is also possible to adopt a plasma generating means or the like.
[0138]
  15 (a) and 15 (b)As shown in FIG. 5, the other electrode 13 can be disposed in the vicinity of the anode electrode side and / or the opposite side of the cathode electrodes 5 and 11 where hollow cathode discharge occurs. The other electrode 13 is formed with a plurality of small holes 13 a having an opening width smaller than the opening width W of the through hole 11 b formed in the concave portion 5 a formed in the cathode electrode 5 or the cathode electrode 11 which is a hollow body. Alternatively, the other electrode 13 may have a mesh shape. Even in the case of a cathode electrode having a through hole in which a hollow cathode discharge is generated, similarly, another electrode in which many small holes smaller than the opening width W of the through hole can be arranged. .
[0139]
  The other electrode 13 is biased to an arbitrary voltage including a floating state, and is particularly preferably set to a voltage value between the voltage of the grounded anode electrode 6 and the maximum value of the space potential of the plasma, Alternatively, it is set to a voltage value between the voltage of the cathode electrode 5 where the hollow cathode discharge is generated and the maximum value of the space potential of the plasma.
[0140]
  Further, a small hole 13a formed in the other electrode 13 is provided.FIG.As shown in FIG. 5, if the cathode electrodes 5 and 11 are formed at positions corresponding to the recesses 5a or the through holes 11b, the electrons are further confined in the hollow cathode discharge region, and an ultra-high density hollow cathode that is a discharge of a larger current. Discharge is possible.
[0141]
  Or16 (a) and 16 (b)As shown in FIG. 5, in the concave portion 5a ″ formed in the cathode electrode 5 ″ and the through hole 11b ″ formed in the cathode electrode 11 ″, the area of the opening portion is the other portion of the concave portion 5a ″ and the through hole 11b ″. By making it sufficiently smaller than the cross-sectional area, the electrons can be efficiently confined in the concave portion 5a ″, the through hole 11b ″ or the hollow portion which is a hollow cathode discharge region. In the figure, the concave portion 5a ″ and the through hole 11b ″ have a cylindrical upper half and a hemispherical lower half, but may be conical, pyramidal, or spindle-shaped.
[0142]
  FIG.Of the present inventionExample 8It is the schematic of the surface treatment apparatus 27 which is. The apparatus 27 is different from the first embodiment described above in that the portion where the anode electrode 14 faces the cathode electrode 5 is a hollow body, but the other configuration is substantially the same as the surface treatment apparatus 1 of the first embodiment. It is.
[0143]
  A portion of the anode electrode 14 facing the cathode electrode 5 is a hollow body 14a, and a single plasma that penetrates the upper wall portion 14b and the lower wall portion 14c in a straight line at the center of the hollow body 14a. An air outlet 7 is formed. Furthermore, in the present embodiment, the facing distance along the formation direction of the plasma outlet 7 of the cavity 14a so that the inside of the cavity 14a of the anode electrode 14 can be a generation region of a hollow anode discharge, That is, in the drawing, the vertical height H is set to a range satisfying either H ≦ 5L (e) or H ≦ 20X. However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X is the thickness of the sheath layer generated under the desired plasma generation conditions. The height H inside the cavity is preferably set in the range of X / 20 ≦ H, and more preferably in the range of X / 5 ≦ H.
[0144]
  In this embodiment, in addition to the hollow anode discharge at the plasma outlet 7 and the hollow cathode discharge at the recess 5a of the cathode electrode 5, a hollow anode discharge is generated inside the cavity 14a of the anode electrode 14, and the anode New plasma is also generated inside the cavity 14 a of the electrode 14. Therefore, the density of the process plasma that reaches the substrate S is further increased and the number of active species that contribute to the film forming process is increased, so that the surface treatment speed is improved and the treatment quality is further improved.
[0145]
  In the illustrated example, the internal height H of the hollow body 14a is constant. However, the height H may not be constant. In order to generate the hollow anode discharge uniformly over substantially the entire area inside the cavity 14a, the height H inside the cavity near the center is reduced according to the frequency of the applied power or according to other conditions, and the outer edge direction. It is preferable to gradually increase the height H, or increase the height H near the center and gradually decrease the height H in the outer edge direction.
[0146]
  Alternatively, the hollow body 14a does not need to generate a hollow anode discharge in the entire inside thereof, and if the hollow anode discharge can be generated in at least a part, the quality of the surface treatment and the improvement of the processing speed can be recognized.
[0147]
  FIG.Is a modification of the anode electrode 14 which is the above-described hollow body. The anode electrode 14 described above was formed through the single plasma outlet 7 in the center of the cavity 14a.FIG.It is also possible to form a plurality of through-holes 14d as plasma outlets that communicate with the inside of the cavity, respectively, in the upper wall portion 14b and the lower wall portion 14c of the cavity body 14a. . In this case, it is preferable that the through hole 14d of the upper wall portion 14b and the through hole 14d of the lower wall portion 14c are formed so as to be shifted from each other so as not to line up and down. Furthermore, the through hole 14d32 to 35It is preferable to form with the arrangement of
[0148]
  Also, the plurality of through holes 14d may not have the same opening width W, and different opening widths W may be appropriately set in order to uniformly generate hollow anode discharge in the plurality of through holes 14d. it can. In particular, the through hole 14d near the center decreases the opening width W and gradually increases the opening width W in the outer edge direction according to the frequency of the applied power or according to other conditions, or increases the opening width W near the center. It is preferable that the opening width W be gradually increased in the outer edge direction.
[0149]
  Further, the length T of the through hole 14d, that is, the thickness T of the lower wall portion 14b in the case of this embodiment, is generally set to have a lower limit of X / 50. The upper limit is determined by device size constraints. The length T of the through hole 14d is preferably 0.1 to 70 mm in the case of the gas pressure and diameter described above.
[0150]
  In the present embodiment, the through hole 14d has a circular cross section, but may have any other shape such as an ellipse, a rectangle, a polygon, and an indefinite shape. The cross-sectional area may not be constant, and the cross-sectional area may be changed in the axial direction. Furthermore, the through hole 14d has a slit structure with a rectangular cross section, orFIG.A slit structure having a one-dimensional extension such as a spiral shape or a meandering shape as shown in FIG. In the case of such a slit structure, the opening width W of the through hole 14d is the slit width, and this slit width is set within the above-described range. Moreover, you may form a partial unevenness | corrugation in the inner wall face of the said through-hole 11b. The plurality of through holes 14d do not have to have the same size and the same form, and a plurality of through holes 14d having different sizes and forms may be formed.
[0151]
  The anode electrode 14 'can be formed with a gas supply port 8' that opens to the inner wall surface of the through hole 14d or the inside of the hollow body 14a. For example, in the case of a film forming process, only the carrier gas is introduced into the plasma generation chamber 3, and the source gas such as monosilane is introduced from the gas supply port 8 'of the anode electrode 14'. It is possible to prevent decomposition in an unnecessary space and to efficiently contribute the source gas to the film forming process. The gas supply ports 8 'can be provided in all of the plurality of through holes 14d, or the gas supply ports 8' can be provided only in some of the through holes 14d. Further, a plurality of gas supply ports 8 'can be opened on the inner wall surface of the hollow body 14a.
[0152]
  Further, a modified example in which the plasma density generated by hollow anode discharge in the hollow body 14a and the through hole 14d in the anode electrode 14 ′ is increased.19 (a) and 19 (b)Shown in
  First, from the viewpoint of efficiently generating a hollow anode discharge in the through hole 14d, it is advantageous that the length T of the through hole 14d is large, and a stronger plasma can be generated. However, it is desirable that the upper and lower wall portions 14b and 14c of the anode electrode have a minimum thickness that can withstand the gas pressure and applied power introduced into the cavity from the viewpoint of material cost.
[0153]
  Therefore, in order to increase the length T of the through hole 14d, it is desirable to attach the nozzle body 12 to the periphery of the through hole 14d of the lower wall portion 14c. The nozzle body 12 may project from the through-hole 14d toward the substrate processing chamber 4 or project into the cavity body 14a. Furthermore, you may project on both sides. The nozzle body 12 isFIG. 19 (a)As shown in FIG. At this time, the magnet 10 is preferably arranged so as not to be directly exposed to the plasma.
[0154]
  In addition,FIG. 19 (a)Each of the nozzle bodies 12 shown in FIG. 5 is arranged with its center line aligned with the line of the through hole 14d, but the center line of the nozzle body 12 is arranged at an angle with respect to the axis of the through hole 14d. In other words, the nozzle body 12 can be arranged obliquely. Also,FIG. 19 (a)The nozzle body 12 shown in FIG. 5 is a cylinder having a constant cross-sectional area, but is not limited to such a shape, and may be a cylinder having a shape that gradually increases or decreases its cross-sectional area. Furthermore, a tubular nozzle body can be arranged in a spiral shape.
[0155]
  Further, in order to increase the surface area of the anode electrode 14 'with which the plasma contacts, a partition wall extending in the vertical direction or a partition wall extending in the horizontal direction is provided inside the cavity 14a of the anode electrode 14', and a plurality of interiors are provided. It can also be divided into chambers. In addition, all the through-holes 14d formed in each divided internal chamber may be the same or different. The partition extending in the vertical direction may be formed with a gap between the upper and lower wall portions 14b and 14c of the hollow body 14a, and the chambers may be communicated with each other.
[0156]
  The anode electrode 14 'includesFIG. 19 (b)As shown in FIG. 4, the magnet 10 is placed on the inner peripheral surface of each through-hole 14d and the upper and lower wall portions 14b and 14c of the cavity 14a so as to apply a magnetic field to the inside of the through-hole 14d and the cavity 14a that are plasma outlets. Alternatively, it can be embedded in the peripheral wall portion or arranged in the vicinity thereof. The magnet 10 is applied with a magnetic field such that the direction of the lines of magnetic force thereof is parallel to the axial direction of the through hole 14d, or the direction of the lines of magnetic force is applied parallel to the upper and lower wall portions 14b, 14c. It is preferable that it is arranged.
[0157]
  Thus, by forming a magnetic field inside the through hole 14d and the cavity body 14a, the trajectory of electrons in the plasma generated therein is adjusted by the magnetic field, and inside the through hole 14d and the cavity body 14a. Electrons can stay for a long time. By adjusting the electron trajectory, the action time of the electrons on the source gas can be extended without increasing the electron energy (electron temperature), so that the generation of active species is promoted and the film formation rate is improved.
[0158]
  20 to 22Mentioned aboveExample 8It is the schematic of the surface treatment apparatuses 28-30 by the 1st-3rd modification of this.FIG.The surface treatment device 28 shown inExample 8The cathode electrode 5 is changed to a cathode electrode 11 having a hollow body, and the hollow hole of the cathode electrode 11 and the through hole 11b formed in the cathode electrode 11 are used as a hollow cathode discharge region.
[0159]
  FIG.The surface treatment device 29 shown inExample 8The cathode electrode 5 is changed to a cathode electrode 11 'which forms a hollow body and the inner wall surface inside the cavity is insulated, and a through hole 11b formed in the cathode electrode 11' is used as a hollow cathode discharge region. Also,In FIG.The surface treatment apparatus 30 shown isExample 8The cathode electrode 5 is changed to a flat plate electrode 5 ', and the cathode electrode 5' does not generate a hollow cathode discharge but generates only a hollow anode discharge.
[0160]
  All of these variations areExample 8And the other embodiments of the present invention described above, each having the effects of the embodiments described above. Therefore, in any of the modifications, the density of the process plasma is increased by the hollow anode discharge or the hollow cathode discharge, and various processing speeds are remarkably improved.
[0161]
  FIG.Of the present inventionNinth embodimentIt is the schematic of the surface treatment apparatus 40 which is. In the surface treatment apparatus 40, the inside of the hollow anode electrode 17 constitutes a substrate processing chamber 4 '.
  The hollow anode electrode 17 has a through hole 17b formed at the center of the upper wall portion 17a, and this through hole 17b constitutes a plasma outlet. The central portion of the inner surface of the lower wall portion 17c of the anode electrode 17 constitutes a substrate support, and a plurality of exhaust ports 17d are formed in the peripheral portion of the lower wall portion 17c. Further, a heating means for the substrate can be provided in the central portion of the lower wall portion 17c. The substrate support position and the exhaust port 17d formation position in the anode electrode 17 are not limited to those described above, and any position can be selected.
[0162]
  In the present embodiment, the opening width W of the through hole 17b is set to either W ≦ 5L (e) or W ≦ 20X so that the through hole 17b of the anode electrode 17 can be a hollow anode discharge generation region. Is set to satisfy the range. Further, the opening width W is preferably set in a range of X / 20 ≦ W, and more preferably set in a range of X / 5 ≦ W. In the present embodiment, the height H inside the cavity is either H ≦ 5L (e) or H ≦ 20X so that the inside of the cavity of the anode electrode 17 can also be a generation region of a hollow anode discharge. It is set in a range that satisfies the above. The height H inside the cavity is also preferably set in the range of X / 20 ≦ H, and more preferably in the range of X / 5 ≦ H.
[0163]
  However, L (e) is the atom or molecular species having the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) generated by decomposition under the desired plasma generation conditions. X is the thickness of the sheath layer generated under the desired plasma generation conditions.
[0164]
  In the substrate processing apparatus 40, the substrate processing chamber 4 ′ is formed inside the cavity of the anode electrode 17, and a hollow anode discharge is generated inside the cavity of the anode electrode 17. The processing speed is also significantly improved. However, this substrate processing apparatus 40 is unsuitable for the film forming process since ion damage to the substrate S due to plasma is large, and the apparatus 40 is suitable for the etching, ashing or ion doping process.
[0165]
  24 (a) and 24 (b)Is a modification of the hollow anode electrode constituting the substrate processing chamber 4 '.FIG. 24 (a)The anode electrode 17 ′ shown in FIG. 5 is different from the above-described anode electrode 17 in that a plurality of through holes 17b constituting a plasma outlet are formed in the upper wall portion 17a. The through hole 17b is32 to 35It is preferable to form in the arrangement as shown in FIG.
[0166]
  The plurality of through holes 17b have a circular cross section in the present embodiment, but may have any other shape such as an ellipse, a rectangle, a polygon, and an indefinite shape. The cross-sectional area may not be constant, and the cross-sectional area may be changed in the axial direction. Furthermore, the through hole 17b has a slit structure with a rectangular cross section, orFIG.A slit structure having a one-dimensional extension such as a spiral shape or a meandering shape as shown in FIG. In the case of such a slit structure, the opening width W of the through hole 17b is the slit width, and this slit width is set within the above-described range. Moreover, you may form a partial unevenness | corrugation in the inner wall face of the said through-hole 17b. The plurality of through holes 17b do not have to have the same size and the same form, and a plurality of through holes 17d having different sizes and forms may be formed.
[0167]
  Also,FIG. 24 (b)The anode electrode 17 ″ shown in FIG. 1 is configured such that the magnet 10 is connected to the inner peripheral surface of each through-hole 17b or the exhaust port 17d and the inside of the cavity so as to apply a magnetic field to the inside of the through-hole 17b and the exhaust port 17d, which are plasma outlets. The magnet 10 can be embedded in the vicinity of the upper and lower wall portions 17a, 17c, or the peripheral wall portion, or can be disposed in the vicinity thereof. It is preferable that the magnetic field is applied in such a manner that the magnetic field is applied, or the direction of the magnetic lines of force is parallel to the upper and lower wall portions 17a and 17d.
[0168]
  Thus, by forming a magnetic field inside the through-hole 17b or the cavity which is a plasma outlet, the trajectory of electrons generated in the plasma is adjusted by the magnetic field, and an electron is inside the through-hole 17b or the cavity. Can stay longer. By adjusting the electron trajectory, the action time of the electrons on the source gas can be extended without increasing the electron energy (electron temperature), so that the generation of active species is promoted and the film formation rate is improved.
[0169]
  FIG.Shows a modification for facilitating the occurrence of hollow discharge in various through holes. sameFIG.Then, the plasma blower outlet 7 formed in the anode electrode 6 is demonstrated to an example.
  FIG. 25 (a)In the modification shown in FIG. 2, a plate-like insulator 18 is disposed in close contact with the lower surface of the anode electrode 6, and another electrode 19 made of a metal plate is disposed on the lower surface of the insulator 18. The plasma outlet 7 is formed through the anode electrode 6, the insulator 18, and the other electrode 19. A DC bias or an AC bias (including a high frequency and a pulse) is applied to the other electrode 19 so that the potential is lower than the potential of the anode electrode.
[0170]
  Here, the plasma potential is determined by the potential of the electrode with which most of the plasma is in contact, that is, the potential of the anode electrode 6 in this case. Compared to the area of the anode electrode 6, the plasma outlet 7 has a very small contact area with the plasma, but a bias is applied to the plasma outlet 7 to freely change the potential difference between the plasma potential and the plasma outlet. It becomes possible to control. Therefore, even if the electric potential difference between the plasma potential and the anode electrode 6 is usually small and a low power discharge at which no hollow plasma can be generated at the plasma outlet 7, a bias is applied to the other electrode 19. Since the potential difference between the plasma and the plasma outlet 7 can be increased, the generation of hollow plasma at the plasma outlet 7 can be induced.
[0171]
  Examples of other electrode arrangements that can freely set the potential of the plasma outlet 7 includeFIG. 25 (b)As shown in FIG. 8, the ring-shaped insulator 18a and the other ring-shaped electrode 19a can be placed on only the lower surface of the portion of the anode electrode 6 where the plasma outlet 7 is formed.
[0172]
  Also,FIG. 25 (c)As shown in the figure, another ring-shaped electrode 19b may be disposed on the inner wall surface of the plasma outlet 7 of the anode electrode 6 via a ring-shaped insulator 18b, orFIG. 25 (d)As shown in FIG. 5, another electrode 19c in the form of a cylindrical nozzle can be disposed on the inner wall surface of the plasma outlet 7 of the anode electrode 6 via a ring-shaped insulator 18b.
  Such a structure can be similarly applied to a case where a plurality of through holes are formed in the anode electrode, or to various through holes such as a through hole formed in the cathode electrode.
[0173]
  In the various embodiments and modifications of the present invention described above, high-frequency power is supplied to the plasma generating electrode by the high-frequency power source P, but a DC voltage can also be applied by a DC power source. Alternatively, the bias may be applied by a DC or AC power source or a pulse power source, respectively.
  Further, a mesh-like electrode may be installed between the substrate S disposed in the surface treatment chamber 4 and the plasma outlet 7 to configure a triode type, and various biases may be applied.
[0174]
  Furthermore, in any of the above-described embodiments, the inside of the casing 2 of the surface treatment apparatus is divided into two vertically by the anode electrode 6 to form the plasma generation chamber 3 on the upper side and the substrate processing chamber 4 on the lower side. It is not limited to such an apparatus.
[0175]
  26 to 31Shows a horizontal cross-sectional view of a surface treatment apparatus according to another embodiment of the present invention.
  In FIG.Showing the present invention10th embodimentIn the surface treatment apparatus 41, the casing 32 is a bottomed cylindrical body, and the inner surface of the peripheral wall is used as the substrate support 9. In this case, a cathode electrode 35 made of a small diameter cylindrical body and an anode electrode 36 made of a cylindrical body having a diameter larger than that of the cathode electrode 35 are arranged in the casing 32 with their central axes aligned. ing.
[0176]
  A plurality of plasma outlets 37 having a predetermined shape and arrangement are formed in the anode electrode 36, and a region between the anode electrode 36 and the casing 32 constitutes a substrate processing chamber 34 in the present invention, and A region between the cathode electrode 35 and the anode electrode 36 constitutes the plasma generation chamber 33 in the present invention. Further, a plurality of concave portions 35a parallel to the axial direction are formed on the peripheral wall surface of the cathode electrode 35 with a predetermined phase difference. When the cathode electrode 35 is a hollow body, a through hole may be formed instead of the recess 35a, and a carrier gas and a source gas may be supplied into the cavity.
[0177]
  OrIn FIG.Showing the present invention11th embodimentAs in the surface treatment apparatus 42, a cylindrical body with the largest diameter is used as the cathode electrode 35, an anode electrode 36 made of a cylindrical body is arranged inside the cathode electrode 35, and a cylindrical body 39 with the smallest diameter is arranged at the center. It can also be arranged. In this case, the outer peripheral surface of the central cylindrical body 39 constitutes a support for the substrate W. A plurality of concave portions 35a parallel to the axial direction are formed on the inner peripheral surface of the cathode electrode 35 with a predetermined phase difference. A plasma outlet 37 having a predetermined shape and arrangement is formed in the anode electrode 36. Note that a casing may be disposed further outside the cathode electrode 35.
[0178]
  this26 and 27Shown inTenth and eleventh embodimentsEven in this case, by setting the opening width of the plasma outlet 37 within the range defined by the present invention, a hollow anode discharge is generated at the outlet 37. Further, by setting the opening width of the recess 35a within the range of the present invention, a hollow cathode discharge is generated in the recess 35a.
[0179]
  Further, the anode electrode 35 and the cathode electrode 36 are formed of a hollow body, a through hole is formed in a surface facing each other electrode, and hollow discharge is generated in the through hole, and at least a part of the inside of the cavity is formed. A hollow discharge can be generated. In that case, the plasma that contributes to the surface treatment has a higher density, and the speed of the surface treatment is improved.
[0180]
  Such an apparatus in which the cathode electrode 35 and the anode electrode 36 are formed of a cylindrical body is useful when surface treatment is performed on a cylindrical substrate such as a photosensitive drum. Alternatively, by using a part of the curved surface of the cylinder, it is possible to reduce the equipment space when performing surface treatment such as film formation and etching continuously by roll-to-roll on a substrate made of a band-shaped film member. Therefore, it is preferable.
[0181]
  In addition, each plasma generating electrode is described above.26 and 27Or a spherical shape having a cross-sectional shape as shown in FIG.28 and 29Of the present invention shown in12th and 13th embodimentsEach of the plasma generating electrodes 35 and 36 can be formed into a part of a curved surface such as a semicircular cylinder or hemisphere. Thus, by making the plasma generating electrode spherical or hemispherical or partially curved, it is possible to perform uniform surface treatment even on a specially shaped substrate such as a spherical semiconductor.
[0182]
  Furthermore,30 and 31Of the present invention shown in14th and 15th embodimentsAs in the case of the surface treatment devices 45 and 46, the plasma generating electrodes 35 and 36 can be formed into a cylinder having a square cross section. Or it can also be set as the cylinder or polyhedron shape of a polygonal cross section. Thus, by making the plasma generating electrodes 35 and 36 into a square shape, the space for the apparatus can be reduced. Further, the plasma generating electrodes 35 and 36 having various shapes are formed of a hollow body, a through hole is formed on a surface facing each other electrode, and hollow discharge is generated in the through hole. It is also possible to increase the plasma density by generating a hollow discharge at least partially.
[Brief description of the drawings]
FIG. 1 is a schematic view of a surface treatment apparatus according to a first embodiment of the present invention.
FIG. 2 is a schematic view showing an arrangement example of gas supply ports according to a modified example of the apparatus.
FIG. 3 is a schematic view of a surface treatment apparatus according to a second embodiment of the present invention.
FIG. 4 is a schematic view showing another arrangement mode of the magnet with respect to the cathode electrode.
FIG. 5 is a schematic view of a surface treatment apparatus according to a third embodiment of the present invention.
FIG. 6 is a schematic view of a surface treatment apparatus according to a fourth embodiment of the present invention.
FIG. 7 is a schematic view showing another arrangement of magnets with respect to a hollow cathode electrode.
FIG. 8 is a schematic view showing still another arrangement mode of the magnet with respect to the hollow cathode electrode.
FIG. 9 is a schematic view of a cathode electrode according to a modification of the devices of the third and fourth embodiments.
FIG. 10 is a schematic view showing an example of arrangement of gas supply ports in the modified example.
FIG. 11 is a schematic view of a surface treatment apparatus according to a fifth embodiment of the present invention.
FIG. 12 is a schematic view of a surface treatment apparatus according to a sixth embodiment of the present invention.
FIG. 13 is a schematic view showing another embodiment of a hollow cathode electrode.
FIG. 14 is a schematic view of a surface treatment apparatus according to a seventh embodiment of the present invention.
[FIG.FIG. 11 is a schematic view of a cathode electrode portion in a surface treatment apparatus according to another embodiment of the present invention.
[FIG.FIG. 11 is a schematic view of a cathode electrode portion in a surface treatment apparatus according to still another embodiment of the present invention.
[FIG.] Of the present invention8thIt is the schematic of the surface treatment apparatus which is an Example.
[FIG.】 the above8thIt is the schematic which shows the modification of the anode electrode in an Example.
[FIG.】 the above8thIt is the schematic which shows the other modification of the anode electrode in an Example.
[FIG.】 the above8thIt is the schematic of the surface treatment apparatus which is the 1st modification of an Example.
[FIG.】 the above8thIt is the schematic of the surface treatment apparatus which is the 2nd modification of an Example.
[FIG.】 the above8thIt is the schematic of the surface treatment apparatus which is the 3rd modification of an Example.
[FIG.] Of the present invention9thIt is the schematic of the surface treatment apparatus which is an Example.
[FIG.】 the above9thIt is the schematic which shows the modification of the anode electrode in an Example.
[FIG.FIG. 11 is a schematic view showing a preferred modification of various through holes of the present invention.
[FIG.] Of the present invention10thIt is a schematic sectional drawing of the horizontal direction of the surface treatment apparatus by an Example.
[FIG.] Of the present invention11thIt is a schematic sectional drawing of the horizontal direction of the surface treatment apparatus by an Example.
[FIG.] Of the present invention12thIt is a schematic sectional drawing of the horizontal direction of the surface treatment apparatus by an Example.
[FIG.] Of the present invention13thIt is a schematic sectional drawing of the horizontal direction of the surface treatment apparatus by an Example.
[FIG.] Of the present invention14thIt is a schematic sectional drawing of the horizontal direction of the surface treatment apparatus by an Example.
[FIG.] Of the present invention15thIt is a schematic sectional drawing of the horizontal direction of the surface treatment apparatus by an Example.
[FIG.It is a diagram showing an example of arrangement of a large number of through holes or recesses.
[FIG.FIG. 11 is a view showing another arrangement example of a large number of through holes or recesses.
[FIG.FIG. 11 is a view showing still another example of arrangement of a large number of through holes or recesses.
[FIG.FIG. 11 is a view showing still another example of arrangement of a large number of through holes or recesses.
[FIG.An explanatory view of a spiral through hole or recess.
[Explanation of symbols]
      1,20-30, 40-46 Surface treatment equipment
      2 Casing
      2a Upper wall
      2b wall
      3 Plasma generation chamber
      4 Substrate processing chamber
      5 Cathode electrode
      5a recess
      6 Anode electrode
      7 Plasma outlet
      8 Gas supply port
      9 Substrate support
    10 Magnet
    11 Cathode electrode
    11a Lower wall
    11b Through hole
    11c Upper wall
    11d Gas supply port
    11e Bulkhead
    12 Nozzle body
    13 Other electrodes
    13a small hole
    14 Anode electrode
    14a Hollow body
    14b Upper wall
    14c Lower wall part
    14d through hole
    15 Cathode electrode
    15a Lower wall
    15b Through hole
    15c upper wall
    15d through hole
    15e partition wall
    16 Cathode electrode
    16a Hollow electrode member
    16b Connection port
    17 Anode electrode
    17a Upper wall
    17b Through hole
    17c Lower wall part
    17d Exhaust port
    18 Plate insulator
    18a Ring insulator
    18b Ring insulator
    19 Other electrodes in plate shape
    19a Ring-shaped other electrode
    19b Other electrode in ring shape
    19c Other electrode in the form of a cylindrical nozzle
    32 casing
    33 Plasma generation chamber
    34 Substrate processing chamber
    35 Cathode electrode
    35a recess
    36 Anode electrode
    37 Plasma outlet
    39 Substrate support
      S substrate
      P High frequency power supply

Claims (9)

Plasma is generated by the plasma generating means in a casing having a plasma generating means, a raw material gas inlet, and a substrate support table to turn the source gas into plasma, and the surface of the substrate placed on the substrate support table is converted into plasma. A surface treatment apparatus for treating,
The casing is defined in two chambers via an anode electrode between a plasma generation chamber provided with the plasma generation means and a substrate processing chamber provided with the substrate support.
The substrate processing chamber and the plasma generation chamber are communicated with each other via one or more plasma outlets formed in the anode electrode ,
At least one of the plasma outlets is a hollow discharge generation area,
The plasma generation chamber is provided with a hollow plasma generation electrode having one or more hollow discharge generation regions.
The surface treatment apparatus characterized by the above-mentioned. Opening width W (1) of the smallest portion in at least one said plasma outlet is, W (1) ≦ 5L ( e) or W (1) is set in a range satisfying either of ≦ 20X composed claim 1 The surface treatment apparatus described in 1.
However, L (e): under the desired plasma generation conditions, the atom or molecular species with the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) that are decomposed and generated therefrom ( Mean free path of electrons with respect to active species) X: thickness of sheath layer generated under desired plasma generation conditions The hollow plasma generation electrode is made has one or more recesses on the surface facing the plasma generated by the plasma generating means comprises at least one said recess is with the hollow discharge generation area according to claim 1 or 2, wherein Surface treatment equipment. The hollow plasma generating electrode is a hollow body, and the electrode has at least one through hole communicating with the inside of the cavity at a portion facing the plasma generated by the plasma generating means. The surface treatment apparatus of Claim 1 or 2 made into the said hollow discharge generation | occurrence | production area. Opening width W of the smallest portion in the recess or the through hole (2) is, W (2) ≦ 5L (e) or W (2) is set in a range satisfying either of ≦ 20X composed claim 3 or 4. The surface treatment apparatus according to 4 .
However, L (e): under the desired plasma generation conditions, the atom or molecular species with the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) that are decomposed and generated therefrom ( Mean free path of electrons with respect to active species) X: thickness of sheath layer generated under desired plasma generation conditions The hollow plasma generating electrode is a hollow body, and the electrode has one or more through holes communicating with the inside of the cavity at a portion facing the plasma generated by the plasma generating means, and at least a part of the inside of the cavity is formed. The surface treatment apparatus according to claim 1 , wherein the surface treatment apparatus is a hollow discharge generation region. Facing distance H of the cavity inside along the formation direction of the through hole of the hollow plasma generation electrode according to claim 6 comprising is set in a range satisfying either of H ≦ 5L (e) or H ≦ 20X Surface treatment equipment.
However, L (e): under the desired plasma generation conditions, the atom or molecular species with the smallest diameter among the source gas species and the electrically neutral atoms and molecular species (active species) that are decomposed and generated therefrom ( Mean free path of electrons with respect to active species) X: thickness of sheath layer generated under desired plasma generation conditions The surface treatment apparatus according to any one of claims 1 to 7 , wherein a magnetic field is formed in the vicinity of the plasma outlet and / or in the vicinity of the recess, the through hole, and / or in the cavity. The surface treatment apparatus according to any one of claims 1 to 8 , further comprising a potential applying unit for applying a desired potential to the substrate.

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