JP4464550B2

JP4464550B2 - Plasma processing equipment

Info

Publication number: JP4464550B2
Application number: JP2000357592A
Authority: JP
Inventors: 信雄石井; 保能八坂
Original assignee: Tokyo Electron Ltd
Current assignee: Tokyo Electron Ltd
Priority date: 1999-12-02
Filing date: 2000-11-24
Publication date: 2010-05-19
Anticipated expiration: 2020-11-24
Also published as: JP2001223171A

Description

【０００１】
【発明の属する技術分野】
本発明は、マイクロ波などの高周波のエネルギーによりプラズマを発生させ、そのプラズマにより半導体ウエハなどの被処理基板に対して処理を施すプラズマ処理装置に関する。
【０００２】
【従来の技術】
半導体デバイスの製造工程の中に、半導体ウエハ（以下ウエハという）に対してプラズマを用いて処理を行う工程がある。このようなプラズマ処理を行うための装置として図１７に示すようなマイクロ波プラズマ処理装置が知られている。この装置は、ウエハＷの載置台９０を備えた真空容器９の天井部に例えば石英よりなるマイクロ波透過窓９１を設けると共に、このマイクロ波透過窓９１の上方に平面スロットアンテナ９２を設け、マイクロ波透過窓９１の上方側に電磁シールド部材９６、例えば真空容器９の上端に連続する円筒部分を設けて構成されている。そしてマイクロ波電源部９３からマイクロ波を導波管９４を介して前記アンテナ９２に導き、このアンテナ９２から真空容器９内にマイクロ波を供給して、ガス供給部９５からの処理ガスをプラズマ化し、そのプラズマにより例えばウエハＷの表面に成膜あるいはエッチング処理を施すように構成されている。
【０００３】
このような装置において、ウエハＷに対して面内均一性の高い処理を行うためには、均一性の高いプラズマを生成することが必要である。プラズマの均一性を左右する要因の一つとしてマイクロ波の電界強度分布が挙げられ、特開平３−６８７７１号公報には、マイクロ波の放射分布（電界強度分布）はアンテナの構造により任意に変更できるが、アンテナに入る前に定在波が存在すると定在波の強弱に応じてマイクロ波が放射されるので、アンテナの直前位置（マイクロ波伝搬路の最終端）にマイクロ波吸収体を設けて定在波を抑えれば放射分布が均一になる旨の記載がある。
【０００４】
【発明が解決しようとする課題】
ところで本発明者はアンテナ９２に金属テープを貼り付けてマイクロ波の放射状態を種々変え、載置台９１の位置に取り付けたＣＣＤカメラによりプラズマを観察したところ、プラズマの明るさ分布の様子にさほど変化がなかった。このことからアンテナ９２によりマイクロ波の電界強度分布を調整できても、アンテナ９２からプラズマ発生領域までの間に電界強度分布が乱れる要因があるといえる。即ち本発明者はアンテナ９２から電界強度分布が均一なマイクロ波が出力されていても、アンテナ９２からシース領域（プラズマと透過窓９１とプラズマ発光領域との間における発光が見えない領域）までの間に定在波が発生しているという知見を得た。定在波は横方向に広がるいわば横波であって、マイクロ波伝搬空間が大きくなると側壁部分からの電磁波の反射などに基づいて発生すると考えられる。このためこの定在波に対応してマイクロ波の電界分布の均一性が悪くなり、プラズマの立ち方に強弱が起こって面内均一性の高い処理が困難になる。
【０００５】
本発明はこのような事情の下になされたものでありその目的はアンテナとプラズマ発光領域との間において定在波の発生を抑え、均一性の高いプラズマを発生させて均一性の高い処理を行うことのできるプラズマ処理装置を提供することにある。
【０００６】
【課題を解決するための手段】
本発明の装置は、高周波電源部から平面状のアンテナ及び高周波透過窓を通じて真空容器内にプラズマ生成用の高周波を供給し、真空容器内に供給された処理ガスを高周波のエネルギ−によってプラズマ化し、そのプラズマにより、真空容器内の載置台に載置された基板に対して処理を行うプラズマ処理装置において、定在波の発生を抑えるように構成したものであり、請求項１の発明は、前記高周波透過窓の真空雰囲気側の面からアンテナに至るまでの領域の側周部を囲むように電磁波吸収体を設け、電磁波吸収体は周方向に互いに空間部を置いて多数に分割されたことを特徴とする。各電磁波吸収体の周方向の長さ及び空間部の周方向の長さは、高周波のその部位での波長をλgとすると（１／２）λgよりも小さいことが好ましい。また電磁波吸収体は横断面で見た形状が内側に凸状であるかまたは内側に凸な多角形である構成とすることができる。
【０００７】
更に本発明の他の装置は、前記高周波透過窓とプラズマ発光領域との間から高周波透過窓のアンテナ側の面に至るまでの領域を、定在波の発生を抑えるために、導電体により高周波の伝搬方向と直交方向に複数領域に分割し、前記導電体の載置台側の端部は、前記高周波透過窓から露出してプラズマ発光領域に食い込んでいることを特徴とする。前記導電体の端部がプラズマ発光領域に食い込んでいる食い込み量は例えば５ｍｍ〜１０ｍｍである。
【０００８】
また前記導電体は、例えば中央部が円形またはリング状に形成された第１の導電体を含み、更に放射状に伸びる導電体を複数設けて前記透過窓を周方向に分割するようにしてもよい。第１の導電体の外側に第１の導電体と同心円状にリング状の第２の導電体を設けても良い。互いに径方向に隣合う導電体の径方向の離間距離Ｒ２は例えば高周波の波長をλとすると（１／２）λ≦Ｒ２＜λである。また第１の導電体の内径Ｒ１は、例えば（１／２）λ≦Ｒ１＜λである。前記導電体を設ける領域は例えば高周波透過窓のみであってもよく、この場合高周波透過窓が導電体により分割される。
本発明の更にまた他の装置は、高周波電源部から平面状のアンテナ及び高周波透過窓を通じて真空容器内にプラズマ生成用の高周波を供給し、真空容器内に供給された処理ガスを高周波のエネルギ−によってプラズマ化し、そのプラズマにより、真空容器内の載置台に載置された基板に対して処理を行うプラズマ処理装置において、
前記高周波透過窓とプラズマ発光領域との間から高周波透過窓のアンテナ側の面に至るまでの領域を、定在波の発生を抑えるために、導電体により高周波の伝搬方向と直交方向に分割し、
前記導電体は、載置台の中心軸をほぼ中心とする円形またはリング状に形成された第１の導電体と、前記透過窓を周方向に分割するために各々放射状に伸びかつ周方向に複数設けられた導電体と、を含むことを特徴とする。
【０００９】
【発明の実施の形態】
図１は本発明のプラズマ処理装置の実施の形態を示す断面図である。このプラズマ処理装置は例えばアルミニウム製の円筒状の真空容器１を備えており、この真空容器１には基板であるウエハＷの載置台２が設けられると共に、底部には真空排気を行うための排気管１１が接続され、また例えば側壁にはガス供給部１２が設けられている。前記載置台２には例えば１３．５６ＭＨｚのバイアス電源部２１に接続されたバイアス印加用の電極２２が埋設されると共に、図示しない温度調整部が設けられていてウエハＷを所定の温度に調整できるように構成されている。真空容器１の天井部には誘電体例えば石英やＡｌ2Ｏ3又はＡｌＮなどのセラミックよりなるマイクロ波透過窓３が下方側の領域を真空雰囲気とするようにシール材３ａにより気密に封止して配置されており、この窓３の上方には多数のスロット３１が形成された平面状のアンテナ３２が当該窓３に対向するように設けられている。
【００１０】
前記アンテナ３２の中央部には導波路である同軸の導波管３３の軸部３３ａの一端部が接続されている。同軸の導波管３３の外管３３ｂの下端部は外側に折り曲げられて広げられ更に下側に屈曲して偏平な円筒状の拡径部３４をなしている。同軸の導波管３３の他端部の側面には導波路である矩形状の導波管３５の一端部が接続されており、この矩形状の導波管３５の他端部にはインピーダンス整合部３６を介してマイクロ波電源部３７が設けられている。
【００１１】
一方前記マイクロ波透過窓３の周囲には例えば真空容器１の上部に連続する電磁シールド部材に相当する円筒部２３が設けられ、この円筒部２３の上部は前記拡径部３４の上面レベルに位置しており、この中に拡径部３４が収まっている。前記円筒部２３の内周面にはマイクロ波を吸収する電磁波吸収体４が積層されており、マイクロ波の反射を抑制し、それによって定在波が立つのを抑えている。電磁波吸収体４としては例えばカーボン等を含む抵抗体や水などの誘電損失の大きい誘電体例えば商品名ニコライト（日本高周波株式会社製）を用いることができ、またはフェライト系セラミックスなどの磁性体を用いてもよく、あるいはこれらの組み合わせであってもよい。例えば水を電磁波吸収体４として用いる場合には、円筒部２３の内周面にマイクロ波伝搬領域を囲むように筒状のジャケット部を形成すると共にマイクロ波伝搬領域側を例えばガラス板で構成し，ジャケット部の中に水を通すようにすればよい。
【００１２】
次に上述実施の形態の作用について、基板上にポリシリコン膜を形成する場合を例にとって説明する。先ず図示しないゲートバルブを開いて図示しない搬送アームによりウエハＷを載置台２上に載置する。次いで前記ゲートバルブを閉じた後、真空容器１内を排気して所定の真空度まで真空引きし、ガス供給部１２から成膜ガスである例えばＳｉＨ4 ガス及びキャリアガスである例えばＡｒガスを真空容器１内に供給する。そしてマイクロ波電源部３７から例えば２．４５ＧＨｚ、２．５ｋｗのマイクロ波を出力すると共に、バイアス電源部２１から載置台２に例えば１３．５６ＭＨｚ、１．５ｋｗのバイアス電力を印加する。
【００１３】
マイクロ波電源部３７からのマイクロ波は導波管３５、３３を介して拡径部３４内に伝播され、アンテナ３２のスロット３１を通って真空容器１内に供給され、このマイクロ波により処理ガスがプラズマ化される。そしてＳｉＨ4 ガスが電離して生成された活性種がウエハＷ表面に付着してポリシリコン膜が成膜される。
【００１４】
ここでアンテナ３２から放射されたマイクロ波において、マイクロ波透過窓３の下面（真空雰囲気側の面）に至るまでに定在波（横波）が立とうとしても、マイクロ波の伝搬空間が電磁波吸収体４により囲まれているので、マイクロ波がこの電磁波吸収体４により吸収され、このため定在波の発生が抑えられる。
【００１５】
従って上述の実施の形態によれば、定在波の発生が抑えられた状態でマイクロ波がマイクロ波透過窓３を透過して真空容器１内に導入されるので、定在波による電界強度分布の影響が少なくなり、この結果プラズマ密度が均一になり、ウエハＷに対して面内分布が均一なプラズマ処理、この例では成膜処理を行うことができる。
【００１６】
本発明はアンテナ３２から放射されたマイクロ波が真空容器１内でプラズマを発生させるに至るまでの領域における定在波の発生を抑えることが目的であるため、上述の例のようにアンテナ４からマイクロ波透過窓３の下面に至るまでの領域全体を電磁波吸収体４で囲むことが望ましいが、高さ方向（マイクロ波の伝搬方向）における一部の領域例えばアンテナ３２とマイクロ波透過窓３との間の空間のみを電磁波吸収体４で囲むようにしてもよいし、マイクロ波透過窓３のみを囲むようにしてもよい。
【００１７】
ここで本発明では、アンテナ４からマイクロ波透過窓３の下面に至るまでの領域の側周部の全周に亘って電磁波吸収体４を設けてもよいが、図２及び図３に示すように電磁波吸収体４を周方向に互いに空間部４１を置いてつまり間隙を介して多数に分割してもよい。このような構成の着眼点及び作用効果について説明する。本発明者は、導波管３３の外管３３ｂの途中に導波管を分岐させてそこにプロ−ブを設置し（図示せず）、アンテナ４側からの反射波を検出したところ、電磁波吸収体４を設けることにより、電磁波吸収体４を全く設けない場合に比べて反射波が抑えられることを把握している。このことは、電磁波吸収体４を設けることにより、アンテナ４からマイクロ波透過窓３の下面に至るまでの領域における横方向の定在波（横波）が抑えられていることに対応していると考えられる。
【００１８】
一方、電磁波吸収体４によりマイクロ波の反射を抑えることはできるが、マイクロ波が空間から電磁波吸収体４に当たるときに、マイクロ波が伝搬している領域のインピ−ダンスが急激に変わることになる。例えば電磁波吸収体４として既述の商品名ニコライトを用いたとすると、この材質は比誘電率εがおよそ「９」であるため、空間に対する電磁波吸収体４のインピ−ダンスの比は、１／（εの平方根）、つまりおよそ１／３に下がることになる。このためマイクロ波は誘電率が急激に変わる媒質の境界でマイクロ波の一部が跳ね返されてしまうと考えられる。
【００１９】
そこで電磁波吸収体４を分割してその間に空間部４１を形成すれば、横波からみると、誘電率が急激に変わるのではなく緩やかに変わるといえる。一方電磁波吸収体４とこれに隣接する空間部４１とは、上下方向に厚さをもつコンデンサとして等価的にとらえられる。このためこのコンデンサの比誘電率εr は、図３に示すように互いに隣接する電磁波吸収体４及び空間部４１の横断面積の合計に対する電磁波吸収体４の横断面積の割合（電磁波吸収体４の占有率）をｘとし、電磁波吸収体４及び空間部４１の夫々の比誘電率εr をεr1、εr2とすると、コンデンサの比誘電率εr つまり電磁波吸収体４及び空間部４１を合わせた等価的な電磁波吸収部の比誘電率εr は、
εr ＝εr1・ｘ＋εr2・（１−ｘ）
となる。
【００２０】
このように電磁波吸収体４をいわば間引きすれば、横波からみると、上述の等価的な電磁波吸収部の誘電率が緩やかに変わるのでつまりインピ−ダンスが緩やかに変わるので、反射波が少なくなり、結果としてアンテナ３２の下方側の空間のマイクロ波の乱れが少なく、横方向に見たときに均一性の高いプラズマが得られる。
【００２１】
この場合電磁波吸収体４の周方向の長さＬ１及び空間部４１の長さＬ２はいずれも、マイクロ波のその部位での波長をλgとすると（１／２）λgよりも小さいことが好ましい。その理由については、もし前記Ｌ１が（１／２）λgよりも大きいと、横波の（１／２）波長分が電磁波吸収体４に当たってそこで急激にインピ−ダンスが変わるので反射される確率が高くなるし、前記Ｌ２が（１／２）λgよりも大きいと、横波の１波長分が空間部４１を通り抜けてその外側のアルミニウムの円筒部２３に当たって跳ね返されてしまい、結果として反射波が多くなるからである。なおＬ１、Ｌ２があまり小さいと製作コストが増加するため例えば（１／４）λgよりも大きいことが好ましい。
【００２２】
更に電磁波吸収体４は横断面形状が内側に向けた凸状の形状、例えば図４（ａ）に示すように５角形状であってもよいし、例えば図４（ｂ）に示すように三角形状であってもよいし、あるいは例えば図４（ｃ）に示すように円弧形状であってもよい。このように構成すれば、横波からみると各電磁波吸収体４の誘電率が徐々に変わっているのでより一層横波の反射を抑えることができる。
【００２３】
なおこのように電磁波吸収体４の横断面形状を凸状に形成する構成は、例えば図５に示すように電磁波吸収体４を全周に亘って設ける例に適用してもよい。
【００２４】
以上において、既述のように電磁波吸収体４を多数に分割して各々の間に空間部を形成した場合にマイクロ波がどのようになるのかを評価するために行った実験の結果について述べておく。この実験は、図１の装置においてアンテナ３１と透過窓３との間における領域の側周部に、横幅（周方向の長さ）が２ｃｍ、縦の長さがおよそ４．５ｃｍ、厚さ１ｃｍの前記商品名ニコライトからなる直方体状の誘電体を周方向に沿って間隔をおいて並べ、既述の電磁波吸収体の占有率を０％（電磁波吸収体を用いない）、３３％（互いに隣接する電磁波吸収体の間隔が４ｃｍ）、６７％（互いに隣接する電磁波吸収体の間隔が１ｃｍ）の３通りに設定して行った。
【００２５】
各々の条件下でプロ−ブを用いてイオン飽和電流を測定したところ夫々図６〜図８の結果が得られた。プロ−ブ１は円筒体２３の中心部、プロ−ブ２はプロ−ブ１から半径方向外側に３ｃｍ離れた位置、プロ−ブ３はプロ−ブ１から半径方向外側に１２ｃｍ離れた位置に設けられ、プロ−ブ１〜３を同じ方向に向け、その方向を同時に順次変えていって、イオン飽和電流を測定した値である。従って各図においてプロ−ブ１〜３の検出電流値のずれ（３本のグラフのずれ）は径方向の電流密度の分布に対応し、プラズマの直径方向の密度分布の指標となる。このグラフから占有率が０％つまり電磁波吸収体を設けない場合に比べて、電磁波吸収体を間隔をおいて設ける場合の方が電解強度の分布の均一性が高いといえる。
【００２６】
図９及び図１０は本発明の他の実施の形態を示す図であり、この例ではマイクロ波透過窓３内に小径のリング状の第１の導電体５１及び大径のリング状の第２の導電体５２を、載置台２上のウエハＷの中心軸を中心として同心円状に設け、これによりマイクロ波透過窓３をマイクロ波の伝播方向と直交する方向この例では水平方向に同心円状に分割している。導電体５１、５２はマイクロ波透過窓３の上面から下面まで突き抜けるように設けられ、その材質としては例えばアルミニウムなどを用いることができる。マイクロ波透過窓３を同心円状に分割するとは、中心部が円形またはリング状の領域であり、更にその外側がリング状の領域という意味である。また分割された領域Ａ１、Ａ２の径方向の長さＲはおよそマイクロ波の半波長（１／２）λの長さに設定されている。
【００２７】
このような実施の形態によればマイクロ波の縦方向の波は、導電体５１、５２で分割された領域を通るが、分割領域の径方向の長さが（１／２）λに設定されているので横波が立とうとしても両側に導電体５１、５２があるため立ちにくい。即ち定在波の発生が抑えられる。定在波を立ちにくくするためには、上記のＲは（１／２）λ≦Ｒ＜λであることが好ましい。マイクロ波の周波数が２．４５ＧＨｚの場合λはおよそ１２ｃｍであり、導電体５２の直径はおよそ１８ｃｍである。なお２０ｃｍサイズのウエハＷを処理する場合、導電体５２の外側から例えば（１／２）λ〜１λ程度の距離に円筒部２３が存在するので、導電体５２よりも外側の窓部分においても定在波が立ちにくい。従ってマイクロ波の電界強度の均一性が高いので、結果として面内均一性の高い処理をウエハＷに施すことができる。
【００２８】
またこのような実施の形態において、図１１に示すように第１の導電体５１と第２の導電体５２との間に放射状に複数の導電体５３を設けて、周方向に領域を分割してもよいし、更には第２の導電体５２の外側の領域に放射状に複数の導電体５４を設けて、周方向に領域を分割してもよい。この場合分割領域の大きさについては、径方向の中点（例えば導電体５３の中点）を通る周方向の長さＳ（導電体５１をなす円の中心を中心とし、前記中点を半径としたときの円弧の長さ）が（１／２）λ≦Ｓ＜λであることが好ましく、このような構成によれば周方向に立とうとする定在波の発生を抑えることができるという利点がある。
【００２９】
ここで導電体５１〜５４の下端部は、図１２（ａ）に示すようにプラズマ発光領域に食い込んでいることが好ましい。プラズマ発光領域はマイクロ波透過窓３の下面よりも若干下方側例えば５〜１０ｍｍ程度下方側に存在し、その間の領域はシ−ス領域１００となっており、例えば図１２（ｂ）に示すように導電体５１〜５４の下端部がプラズマ発光領域の上面とほぼ同じ位置とすると、横波が導電体５１〜５４の下側のシ−ス領域をすり抜けて結果として定在波が発生してしまう。これに対して導電体５１〜５４の下端部をプラズマ発光領域に食いませておけば、プラズマ発光領域の上面に段差ができるので横波がすり抜けにくくなり、つまり伝搬効率が悪くなり、定在波が立ちにくくなる。なお導電体５１〜５４がプラズマ発光領域に食い込んでいる食い込み量は例えば５ｍｍ〜１０ｍｍ程度である。
【００３０】
図１３及び図１４は本発明の更に他の実施の形態を示す図であり、この例ではマイクロ波透過窓３の下面（真空雰囲気側の面）とプラズマ発光領域との間（シース領域）に導電体例えばアルミニウムよりなるガス供給部６が設けられている。このガス供給部６は載置台２上のウエハＷの中心軸（真空容器１の中心軸）を軸とし、第１の導電体に相当する円形部分６１と、この円形部分６１の外側に当該円形部分６１と同心円状に設けられた第２の導電体に相当するリング状部分６２と、円形部分６１とリング状部分６２との間に径方向に伸びる４本の支持管６３とを備えている。円形部分６１及びリング状部分６２は内部にガス流路が形成されており、これらガス流路は導電体よりなる支持管６３の内部空間を介して連通している。円形部分６１及びリング状部分６２の下面側には多数のガス吐出孔６４が形成され、ガス流路を通ってきた処理ガスがガス吐出孔６４から真空容器１内に供給される。円形部分６１の上面には導電体よりなるガス導入管６５が垂直に接続されており、このガス導入管６５はマイクロ波透過窓３及びアンテナ３２を貫通し、内管３３ａの中を通って導波管３５を介して外部に伸び、図示しないガス供給源に接続されている。前記円形部分６１はマイクロ波透過窓３を貫通する構造であってもよいし、更にアンテナ３２の下面に接続された構造であってもよい。また円形部分６１の代りにリング状体を用いてもよく、その場合これらの内径は、（１／２）λ≦内径＜λの大きさであることが好ましい。またガス導入管６５を用いる場合、マイクロ波から見るとガス導入管６５と軸部３３ａとが同軸導波管になり、この間をマイクロ波が伝搬するので、例えばアンテナ３２と透過窓３との間において、軸部３３ａの内径よりも大きな径で、ガス導入管６５をシールド部材で囲むようにすることが好ましい。
【００３１】
プラズマ発生時にはシース領域は例えばマイクロ波透過窓３の下面から１ｃｍ下方ぐらいまで存在し、ガス供給部６はこのシース領域が形成される領域内に収まる大きさに構成されている。ガス供給部６はシース領域で定在波が発生するのを抑えるために円形部分６１及びリング状部分６２によりマイクロ波の伝搬領域を分割する役割をもっており、このため円形部分６１とリング状部分６２との径方向の離間距離Ｑはλ／２≦Ｑ＜λの大きさに設定されている。
【００３２】
プラズマ発光領域におけるウエハＷと平行な面方向のプラズマ密度分布（活性粒子の密度分布）は、プラズマ発光領域にさしかかる直前のマイクロ波の電界強度分布に大きく依存するので、シース領域にて定在波の発生を抑制することはプラズマ密度の均一性を高める上で有効である。また上述のようにガス供給部６を構成することにより真空容器１内へのマイクロ波（縦波）の導入を妨げることなく広い範囲に亘って処理ガスをウエハＷに供給することができ、この点からもウエハＷに対するプラズマ処理についての高い面内均一性が得られる。
【００３３】
ガス供給部６は既述の理由から下端側がプラズマの発光領域内に多少入り込んでいることが好ましい。またシース領域を分割する導電体にガス供給部の機能を持たせなくてもよく、例えばマイクロ波透過窓３の下面に例えば導電体をなす金属テープを貼り付けてマイクロ波伝搬領域を既述のように分割してもよい。更に本発明では図１のように電磁波吸収体４を用いる構成、マイクロ波透過窓３に導電体５１、５２、５３、５４を設ける構成、シ−ス領域に導電体を設ける構成の２つ以上を組み合わせてもよい。
【００３４】
更にまた本発明はウエハＷのみならず液晶ディスプレイ用ガラス基板上にプラズマ処理を施す場合にも適用でき、この場合には真空容器１を方形状に形成し、例えば図１５に示すようにマイクロ波透過窓３を複数の導電体５５によりＸ方向に分割してもよいし、あるいは複数の導電体５５、５６により図１６に示すようにＸ、Ｙ方向に分割してもよい。この場合互に隣接する導電体５５（５６）の離間距離Ｂ１（Ｂ２）は（１／２）λ≦Ｂ１（Ｂ２）＜λであることが好ましい。
【００３５】
なお処理ガスをプラズマ化するための電源部としてはマイクロ波電源部に限らずＲＦ電源部やＵＨＦ電源部でもよく、本明細書では、これらを高周波電源部として扱っている。またプラズマを生成する手法は、例えばマイクロ波と磁場とにより電子サイクロトロン共鳴を起こして処理ガスをプラズマ化する方法でもよい。更にまた本発明は成膜処理に限らずエッチングやアッシング処理を行う場合に適用してもよい。
【００３６】
【発明の効果】
本発明によれば高周波の電界強度分布の均一性が高く、従って基板と平行な面においてプラズマ密度の均一性が高く、この結果基板に対して均一性の高いプラズマ処理を施すことができる。
【００３７】
【図面の簡単な説明】
【図１】本発明の実施の形態を示す縦断側面図である。
【図２】図１の実施の形態の変形例を示す横断平面図である。
【図３】図２の実施の形態の要部を示す説明図である。
【図４】図２の実施の形態で用いれる電磁波吸収体の変形例を示す横断面図である。
【図５】図１の実施の形態の他の変形例を示す横断平面図である。
【図６】図２の実施の形態の実験結果を示す特性図である。
【図７】図２の実施の形態の実験結果を示す特性図である。
【図８】電磁波吸収体を用いない場合の実験結果を示す特性図である。
【図９】本発明の他の実施の形態を示す縦断側面図である。
【図１０】図９の実施の形態で用いた導電体を示す平面図である。
【図１１】図９の実施の形態で用いた導電体の変形例を示す平面図である。
【図１２】導電体を用いた場合における、導電体とプラズマ発光領域との位置関係の例を示す説明図である。
【図１３】本発明の更に他の実施の形態を示す縦断側面図である。
【図１４】図１３の実施の形態で用いた導電体（ガス供給部）を下側から見た底面図である。
【図１５】本発明の更にまた他の実施の形態に係る導電体を示す平面図である。
【図１６】図１５に示す導電体の変形例を示す平面図である。
【図１７】従来のプラズマ処理装置を示す概略図である。
【符号の説明】
１真空容器
２載置台
Ｗ半導体ウエハ
３マイクロ波透過窓
３３、３５導波管
３７マイクロ波電源部
４電磁波吸収体
４１空間部
５１第１の導電体
５２第２の導電体
６ガス供給部
６１円形部分（第１の導電体）
６２リング状部分（第２の導電体）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus that generates plasma by high-frequency energy such as microwaves and performs processing on a substrate to be processed such as a semiconductor wafer by the plasma.
[0002]
[Prior art]
Among semiconductor device manufacturing processes, there is a process of processing a semiconductor wafer (hereinafter referred to as a wafer) using plasma. A microwave plasma processing apparatus as shown in FIG. 17 is known as an apparatus for performing such plasma processing. In this apparatus, a microwave transmitting window 91 made of, for example, quartz is provided on a ceiling portion of a vacuum vessel 9 provided with a mounting table 90 for a wafer W, and a planar slot antenna 92 is provided above the microwave transmitting window 91, An electromagnetic shield member 96, for example, a cylindrical portion continuous to the upper end of the vacuum vessel 9 is provided above the wave transmission window 91. Then, a microwave is guided from the microwave power source 93 to the antenna 92 through the waveguide 94, and the microwave is supplied from the antenna 92 into the vacuum vessel 9, and the processing gas from the gas supply unit 95 is converted into plasma. For example, a film is formed or etched on the surface of the wafer W by the plasma.
[0003]
In such an apparatus, in order to perform processing with high in-plane uniformity on the wafer W, it is necessary to generate plasma with high uniformity. One of the factors that influence the uniformity of plasma is the microwave electric field intensity distribution. In Japanese Patent Laid-Open No. 3-68771, the microwave radiation distribution (electric field intensity distribution) is arbitrarily changed depending on the antenna structure. However, if a standing wave exists before entering the antenna, microwaves are radiated according to the strength of the standing wave, so a microwave absorber is provided at the position immediately before the antenna (final end of the microwave propagation path). There is a statement that the radiation distribution becomes uniform if the standing wave is suppressed.
[0004]
[Problems to be solved by the invention]
By the way, the present inventor attached a metal tape to the antenna 92 to change the radiation state of the microwave in various ways, and observed the plasma with a CCD camera attached to the position of the mounting table 91. As a result, the brightness distribution of the plasma changed greatly. There was no. Therefore, even if the microwave field strength distribution can be adjusted by the antenna 92, it can be said that there is a factor that disturbs the field strength distribution from the antenna 92 to the plasma generation region. In other words, the present inventor, even if a microwave with a uniform electric field intensity distribution is output from the antenna 92, the antenna 92 to the sheath region (region where light emission between the plasma, the transmission window 91, and the plasma emission region cannot be seen). We obtained the knowledge that a standing wave was generated between them. The standing wave is a so-called transverse wave that spreads in the transverse direction, and is considered to be generated based on the reflection of electromagnetic waves from the side wall when the microwave propagation space is increased. For this reason, the uniformity of the electric field distribution of the microwave is deteriorated corresponding to the standing wave, and the strength of the plasma rises and the processing with high in-plane uniformity becomes difficult.
[0005]
The present invention has been made under such circumstances, and its purpose is to suppress the generation of standing waves between the antenna and the plasma emission region, and to generate a highly uniform plasma to perform a highly uniform treatment. An object of the present invention is to provide a plasma processing apparatus that can be used.
[0006]
[Means for Solving the Problems]
  The apparatus of the present invention supplies a high frequency for plasma generation into a vacuum vessel through a planar antenna and a high frequency transmission window from a high frequency power supply unit, and converts the processing gas supplied into the vacuum vessel into plasma with high frequency energy, In the plasma processing apparatus for processing a substrate mounted on a mounting table in a vacuum vessel by the plasma, the plasma processing apparatus is configured to suppress the generation of standing waves. An electromagnetic wave absorber is provided to surround the side periphery of the area from the surface of the high-frequency transmission window on the vacuum atmosphere side to the antenna.,Electromagnetic wave absorbers are divided into a large number of spaces in the circumferential direction.It is characterized by that.The length in the circumferential direction of each electromagnetic wave absorber and the length in the circumferential direction of the space are preferably smaller than (1/2) λg, where λg is the wavelength of the high frequency at that portion. In addition, the electromagnetic wave absorber may have a configuration in which the shape seen in a cross section is convex inward or a polygon convex inward.
[0007]
  Furthermore, another device of the present invention uses a conductor to suppress the generation of standing waves in a region from between the high-frequency transmission window and the plasma emission region to the antenna-side surface of the high-frequency transmission window. In the direction perpendicular to the propagation direction ofMultiple areasThe end of the conductor on the mounting table side is divided,Exposed from the high-frequency transmission windowIt is characterized by biting into the plasma emission region. The amount of biting into the plasma emission region by the end of the conductor is, for example, 5 mm to 10 mm.
[0008]
  The conductor is, for example, a first conductor having a central portion formed in a circular or ring shape.IncludingProviding a plurality of radially extending conductors;Transparent windowIs divided in the circumferential directionYou may make it do.Concentric with the first conductor outside the first conductorInRing-shaped second conductorIt may be provided.The radial distance R2 between the conductors adjacent to each other in the radial direction is, for example, (1/2) λ ≦ R2 <λ, where λ is the wavelength of the high frequency. The inner diameter R1 of the first conductor is, for example, (1/2) λ ≦ R1 <λ..The region where the conductor is provided may be, for example, only a high-frequency transmission window. In this case, the high-frequency transmission window is divided by the conductor.
  Still another device of the present invention provides:A high frequency for plasma generation is supplied from a high frequency power supply unit to the vacuum vessel through a planar antenna and a high frequency transmission window, and the processing gas supplied into the vacuum vessel is turned into plasma by high frequency energy, and the plasma is used to generate a vacuum vessel. In a plasma processing apparatus that performs processing on a substrate mounted on an internal mounting table,
  The region from the high-frequency transmission window and the plasma emission region to the antenna-side surface of the high-frequency transmission window is divided into a high-frequency propagation direction by a conductor in order to suppress the occurrence of standing waves. ,
The conductor includes a first conductor formed in a circular or ring shape substantially centered on the center axis of the mounting table, and a plurality of conductor conductors extending radially in order to divide the transmission window in the circumferential direction. And a provided conductor.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a sectional view showing an embodiment of the plasma processing apparatus of the present invention. The plasma processing apparatus includes a cylindrical vacuum vessel 1 made of, for example, aluminum. The vacuum vessel 1 is provided with a mounting table 2 for a wafer W as a substrate, and an exhaust for evacuating the bottom. A tube 11 is connected, and a gas supply unit 12 is provided on the side wall, for example. In the mounting table 2, for example, a bias applying electrode 22 connected to a bias power supply unit 21 of 13.56 MHz is embedded, and a temperature adjusting unit (not shown) is provided to adjust the wafer W to a predetermined temperature. It is configured as follows. A microwave transmitting window 3 made of a dielectric material such as quartz, Al2O3, or AlN is disposed on the ceiling of the vacuum vessel 1 so as to be hermetically sealed with a sealing material 3a so that the lower region is in a vacuum atmosphere. A planar antenna 32 in which a large number of slots 31 are formed is provided above the window 3 so as to face the window 3.
[0010]
One end of a shaft portion 33a of a coaxial waveguide 33 serving as a waveguide is connected to the central portion of the antenna 32. The lower end portion of the outer tube 33b of the coaxial waveguide 33 is bent outward and widened, and further bent downward to form a flat cylindrical expanded portion 34. One end of a rectangular waveguide 35 serving as a waveguide is connected to the side surface of the other end of the coaxial waveguide 33, and impedance matching is performed on the other end of the rectangular waveguide 35. A microwave power source unit 37 is provided via the unit 36.
[0011]
On the other hand, around the microwave transmission window 3, for example, a cylindrical portion 23 corresponding to an electromagnetic shield member continuous with the upper portion of the vacuum vessel 1 is provided, and the upper portion of the cylindrical portion 23 is positioned at the upper surface level of the enlarged diameter portion 34. The diameter-expanded portion 34 is accommodated therein. An electromagnetic wave absorber 4 that absorbs microwaves is laminated on the inner peripheral surface of the cylindrical portion 23 to suppress the reflection of the microwaves, thereby preventing the standing waves from standing. As the electromagnetic wave absorber 4, for example, a resistor containing carbon or the like, a dielectric material having a large dielectric loss such as water, for example, a product name Nicolite (manufactured by Nippon Radio Frequency Co., Ltd.), or a magnetic material such as ferrite ceramics is used. Or a combination thereof. For example, when water is used as the electromagnetic wave absorber 4, a cylindrical jacket portion is formed on the inner peripheral surface of the cylindrical portion 23 so as to surround the microwave propagation region, and the microwave propagation region side is formed of, for example, a glass plate. , Water should be passed through the jacket.
[0012]
Next, the operation of the above embodiment will be described by taking as an example the case where a polysilicon film is formed on a substrate. First, a gate valve (not shown) is opened, and a wafer W is placed on the mounting table 2 by a transfer arm (not shown). Next, after closing the gate valve, the inside of the vacuum vessel 1 is evacuated and evacuated to a predetermined degree of vacuum, and a film forming gas such as SiH4 gas and a carrier gas such as Ar gas are supplied from the gas supply unit 12 to the vacuum vessel. 1 is supplied. Then, for example, a microwave of 2.45 GHz and 2.5 kW is output from the microwave power supply unit 37, and a bias power of, for example, 13.56 MHz and 1.5 kW is applied from the bias power supply unit 21 to the mounting table 2.
[0013]
Microwaves from the microwave power supply unit 37 are propagated into the enlarged diameter portion 34 through the waveguides 35 and 33, and supplied into the vacuum vessel 1 through the slot 31 of the antenna 32. The processing gas is generated by the microwaves. Is turned into plasma. Then, active species generated by ionization of SiH4 gas adhere to the surface of the wafer W to form a polysilicon film.
[0014]
Here, in the microwave radiated from the antenna 32, even if a standing wave (transverse wave) stands up to the lower surface (surface on the vacuum atmosphere side) of the microwave transmission window 3, the propagation space of the microwave absorbs electromagnetic waves. Since it is surrounded by the body 4, the microwave is absorbed by the electromagnetic wave absorber 4, so that the generation of standing waves is suppressed.
[0015]
Therefore, according to the above-described embodiment, since the microwave is transmitted through the microwave transmission window 3 and introduced into the vacuum vessel 1 in a state where the generation of the standing wave is suppressed, the electric field intensity distribution due to the standing wave. As a result, the plasma density becomes uniform, and a plasma process with a uniform in-plane distribution on the wafer W, in this example, a film forming process can be performed.
[0016]
The purpose of the present invention is to suppress the generation of standing waves in the region from when the microwave radiated from the antenna 32 reaches the generation of plasma in the vacuum vessel 1. Although it is desirable to surround the entire area up to the lower surface of the microwave transmission window 3 with the electromagnetic wave absorber 4, some areas in the height direction (the propagation direction of the microwave) such as the antenna 32 and the microwave transmission window 3 Only the space between the two may be surrounded by the electromagnetic wave absorber 4, or only the microwave transmission window 3 may be surrounded.
[0017]
Here, in the present invention, the electromagnetic wave absorber 4 may be provided over the entire circumference of the side periphery of the region from the antenna 4 to the lower surface of the microwave transmission window 3, as shown in FIGS. Further, the electromagnetic wave absorber 4 may be divided into a large number through the space 41 in the circumferential direction, that is, through a gap. The focus point and the operational effect of such a configuration will be described. The inventor branched the waveguide in the middle of the outer tube 33b of the waveguide 33, installed a probe (not shown) there, and detected a reflected wave from the antenna 4 side. It is understood that by providing the absorber 4, the reflected wave can be suppressed compared to the case where the electromagnetic wave absorber 4 is not provided at all. This corresponds to the fact that the standing wave (transverse wave) in the lateral direction in the region from the antenna 4 to the lower surface of the microwave transmission window 3 is suppressed by providing the electromagnetic wave absorber 4. Conceivable.
[0018]
On the other hand, the reflection of the microwave can be suppressed by the electromagnetic wave absorber 4, but when the microwave hits the electromagnetic wave absorber 4 from the space, the impedance of the region in which the microwave propagates changes rapidly. . For example, if the above-mentioned trade name Nicolite is used as the electromagnetic wave absorber 4, this material has a relative dielectric constant ε of approximately “9”, so the ratio of the impedance of the electromagnetic wave absorber 4 to the space is 1 / ( The square root of ε), that is, about 1/3. For this reason, it is considered that a part of the microwave is rebounded at the boundary of the medium where the dielectric constant changes rapidly.
[0019]
Therefore, if the electromagnetic wave absorber 4 is divided and the space portion 41 is formed therebetween, it can be said that the dielectric constant changes gradually rather than suddenly when viewed from the transverse wave. On the other hand, the electromagnetic wave absorber 4 and the space part 41 adjacent thereto are equivalently regarded as capacitors having a thickness in the vertical direction. Therefore, the relative dielectric constant εr of this capacitor is the ratio of the transverse area of the electromagnetic wave absorber 4 to the total of the transverse areas of the electromagnetic wave absorber 4 and the space portion 41 adjacent to each other as shown in FIG. The relative dielectric constant εr of the capacitor, that is, the equivalent electromagnetic wave combining the electromagnetic wave absorber 4 and the space portion 41, where εr1 and εr2 are the relative dielectric constant εr of the electromagnetic wave absorber 4 and the space portion 41, respectively. The relative permittivity εr of the absorbing portion is
.epsilon.r = .epsilon.r1.x + .epsilon.r2.multidot. (1-x)
It becomes.
[0020]
If the electromagnetic wave absorber 4 is thinned out in this way, when viewed from a transverse wave, the dielectric constant of the above-described equivalent electromagnetic wave absorbing portion changes gently, that is, the impedance changes gently, so the reflected wave decreases, As a result, there is little disturbance of the microwave in the space below the antenna 32, and plasma with high uniformity can be obtained when viewed in the lateral direction.
[0021]
In this case, both the circumferential length L1 of the electromagnetic wave absorber 4 and the length L2 of the space 41 are preferably smaller than (1/2) λg, where λg is the wavelength of the microwave at that portion. The reason is that if L1 is larger than (1/2) λg, the (1/2) wavelength portion of the transverse wave hits the electromagnetic wave absorber 4 and the impedance changes suddenly there, so that the probability of reflection is high. If L2 is larger than (1/2) λg, one wavelength of the transverse wave passes through the space portion 41 and hits the outer aluminum cylindrical portion 23 and is bounced back, resulting in an increase in reflected waves. Because. If L1 and L2 are too small, the manufacturing cost increases. For example, it is preferably larger than (1/4) λg.
[0022]
Further, the electromagnetic wave absorber 4 may have a convex shape with the cross-sectional shape facing inward, for example, a pentagonal shape as shown in FIG. 4A, or a triangular shape as shown in FIG. 4B, for example. It may be a shape, or may be an arc shape as shown in FIG. If comprised in this way, since the dielectric constant of each electromagnetic wave absorber 4 will change gradually seeing from a transverse wave, reflection of a transverse wave can be suppressed further.
[0023]
In addition, you may apply the structure which forms the cross-sectional shape of the electromagnetic wave absorber 4 in this way to the convex form in the example which provides the electromagnetic wave absorber 4 over a perimeter as shown, for example in FIG.
[0024]
In the above, the results of experiments conducted to evaluate what the microwaves look like when the electromagnetic wave absorber 4 is divided into a large number and spaces are formed between them as described above are described. deep. In this experiment, the lateral width (length in the circumferential direction) is 2 cm, the vertical length is approximately 4.5 cm, and the thickness is 1 cm at the side periphery of the region between the antenna 31 and the transmission window 3 in the apparatus of FIG. The rectangular parallelepiped dielectrics made of the above-mentioned product name Nicolite are arranged at intervals along the circumferential direction, and the occupation rate of the electromagnetic wave absorber described above is 0% (no electromagnetic wave absorber is used), 33% (adjacent to each other) The interval between the electromagnetic wave absorbers was 4 cm) and 67% (the interval between the adjacent electromagnetic wave absorbers was 1 cm).
[0025]
When the ion saturation current was measured using a probe under each condition, the results shown in FIGS. 6 to 8 were obtained. The probe 1 is at the center of the cylinder 23, the probe 2 is at a position 3 cm radially outward from the probe 1, and the probe 3 is at a position 12 cm radially outward from the probe 1. This is a value obtained by measuring the ion saturation current by providing probes 1 to 3 in the same direction and sequentially changing the directions. Accordingly, in each figure, the deviation of the detected current values of the probes 1 to 3 (the deviation of the three graphs) corresponds to the current density distribution in the radial direction and serves as an index of the density distribution in the plasma diameter direction. From this graph, it can be said that the uniformity of the electrolytic strength distribution is higher when the electromagnetic wave absorber is provided at intervals than when the occupation ratio is 0%, that is, when the electromagnetic wave absorber is not provided.
[0026]
FIG. 9 and FIG. 10 are diagrams showing another embodiment of the present invention. In this example, a small-diameter ring-shaped first conductor 51 and a large-diameter ring-shaped second conductor are disposed in the microwave transmission window 3. Are provided concentrically around the central axis of the wafer W on the mounting table 2, whereby the microwave transmitting window 3 is concentrically oriented in a direction perpendicular to the microwave propagation direction. It is divided. The conductors 51 and 52 are provided so as to penetrate from the upper surface to the lower surface of the microwave transmission window 3, and for example, aluminum or the like can be used. Dividing the microwave transmitting window 3 into concentric circles means that the central portion is a circular or ring-shaped region and the outside thereof is a ring-shaped region. The length R in the radial direction of the divided regions A1 and A2 is set to a length of about a half wavelength (1/2) λ of the microwave.
[0027]
According to such an embodiment, the longitudinal wave of the microwave passes through the region divided by the conductors 51 and 52, but the length of the divided region in the radial direction is set to (1/2) λ. Therefore, even if a transverse wave is standing, it is difficult to stand because there are conductors 51 and 52 on both sides. That is, the occurrence of standing waves can be suppressed. In order to make standing waves difficult to stand, R is preferably (1/2) λ ≦ R <λ. When the frequency of the microwave is 2.45 GHz, λ is approximately 12 cm, and the diameter of the conductor 52 is approximately 18 cm. When processing a wafer W having a size of 20 cm, the cylindrical portion 23 exists at a distance of, for example, about (1/2) λ to 1λ from the outside of the conductor 52, so that the window portion outside the conductor 52 is also fixed. There is no standing wave. Accordingly, the uniformity of the electric field strength of the microwave is high, and as a result, a process with high in-plane uniformity can be performed on the wafer W.
[0028]
In such an embodiment, as shown in FIG. 11, a plurality of conductors 53 are provided radially between the first conductor 51 and the second conductor 52 to divide the region in the circumferential direction. Alternatively, a plurality of conductors 54 may be provided radially in a region outside the second conductor 52, and the region may be divided in the circumferential direction. In this case, with respect to the size of the divided region, the length S in the circumferential direction passing through the midpoint of the radial direction (for example, the midpoint of the conductor 53) (centering on the center of the circle forming the conductor 51) The length of the circular arc is preferably (1/2) λ ≦ S <λ, and according to such a configuration, it is possible to suppress the occurrence of a standing wave that stands in the circumferential direction. There are advantages.
[0029]
Here, it is preferable that the lower ends of the conductors 51 to 54 bite into the plasma emission region as shown in FIG. The plasma emission region is slightly below the lower surface of the microwave transmission window 3, for example, about 5 to 10 mm below, and the region between them is a seed region 100, for example, as shown in FIG. If the lower end portions of the conductors 51 to 54 are substantially at the same position as the upper surface of the plasma emission region, the transverse wave passes through the lower sheath region of the conductors 51 to 54, and a standing wave is generated as a result. . On the other hand, if the lower end portions of the conductors 51 to 54 are eaten into the plasma light emitting region, a step is formed on the upper surface of the plasma light emitting region, so that the transverse wave is difficult to pass through. It becomes difficult to stand. It should be noted that the amount of penetration of the conductors 51 to 54 into the plasma emission region is, for example, about 5 mm to 10 mm.
[0030]
FIG. 13 and FIG. 14 are diagrams showing still another embodiment of the present invention. In this example, between the lower surface (surface on the vacuum atmosphere side) of the microwave transmission window 3 and the plasma emission region (sheath region). A gas supply unit 6 made of a conductor such as aluminum is provided. The gas supply unit 6 has the center axis of the wafer W on the mounting table 2 (the center axis of the vacuum vessel 1) as an axis, a circular portion 61 corresponding to the first conductor, and the circular portion 61 outside the circular portion 61. A ring-shaped portion 62 corresponding to a second conductor provided concentrically with the portion 61, and four support tubes 63 extending in the radial direction between the circular portion 61 and the ring-shaped portion 62 are provided. . The circular portion 61 and the ring-shaped portion 62 have gas passages formed therein, and these gas passages communicate with each other via an internal space of a support pipe 63 made of a conductor. A large number of gas discharge holes 64 are formed on the lower surface side of the circular portion 61 and the ring-shaped portion 62, and the processing gas that has passed through the gas flow path is supplied into the vacuum vessel 1 from the gas discharge holes 64. A gas introduction pipe 65 made of a conductor is vertically connected to the upper surface of the circular portion 61. The gas introduction pipe 65 penetrates the microwave transmission window 3 and the antenna 32, and is guided through the inner pipe 33a. It extends outside through the wave tube 35 and is connected to a gas supply source (not shown). The circular portion 61 may have a structure that penetrates the microwave transmission window 3 or may be a structure that is connected to the lower surface of the antenna 32. In addition, a ring-shaped body may be used instead of the circular portion 61, and in this case, the inner diameter is preferably (1/2) λ ≦ inner diameter <λ. Further, when the gas introduction pipe 65 is used, the gas introduction pipe 65 and the shaft portion 33a are coaxial waveguides when viewed from the microwave, and the microwave propagates therebetween, so that, for example, between the antenna 32 and the transmission window 3 In this case, it is preferable that the gas introduction pipe 65 is surrounded by a shield member with a diameter larger than the inner diameter of the shaft portion 33a.
[0031]
When plasma is generated, the sheath region exists, for example, about 1 cm below the lower surface of the microwave transmission window 3, and the gas supply unit 6 is configured to fit within the region where the sheath region is formed. The gas supply unit 6 has a role of dividing the microwave propagation region by the circular portion 61 and the ring-shaped portion 62 in order to suppress the occurrence of standing waves in the sheath region. For this reason, the circular portion 61 and the ring-shaped portion 62 are used. The distance Q in the radial direction is set to λ / 2 ≦ Q <λ.
[0032]
The plasma density distribution in the plane direction parallel to the wafer W in the plasma emission region (density distribution of active particles) largely depends on the electric field strength distribution of the microwave just before reaching the plasma emission region, so that the standing wave in the sheath region Suppressing the occurrence of is effective in increasing the uniformity of the plasma density. Further, by configuring the gas supply unit 6 as described above, the processing gas can be supplied to the wafer W over a wide range without hindering the introduction of the microwave (longitudinal wave) into the vacuum chamber 1. From the point of view, high in-plane uniformity of the plasma processing on the wafer W can be obtained.
[0033]
It is preferable that the lower end side of the gas supply unit 6 slightly enters the plasma emission region for the reasons described above. The conductor that divides the sheath region may not have the function of the gas supply unit. For example, a metal tape that forms a conductor is attached to the lower surface of the microwave transmission window 3 to define the microwave propagation region as described above. You may divide as follows. Further, in the present invention, two or more of a configuration using the electromagnetic wave absorber 4 as shown in FIG. 1, a configuration in which the conductors 51, 52, 53, 54 are provided in the microwave transmission window 3, and a configuration in which the conductor is provided in the sheath region. May be combined.
[0034]
Furthermore, the present invention can be applied not only to the wafer W but also to plasma treatment on a glass substrate for a liquid crystal display. In this case, the vacuum vessel 1 is formed in a square shape, for example, as shown in FIG. The transmission window 3 may be divided in the X direction by a plurality of conductors 55, or may be divided in the X and Y directions by a plurality of conductors 55 and 56 as shown in FIG. In this case, the distance B1 (B2) between the conductors 55 (56) adjacent to each other is preferably (1/2) λ ≦ B1 (B2) <λ.
[0035]
Note that the power supply unit for converting the processing gas into plasma is not limited to the microwave power supply unit, and may be an RF power supply unit or a UHF power supply unit. In this specification, these are handled as a high-frequency power supply unit. In addition, the method for generating plasma may be, for example, a method in which electron cyclotron resonance is caused by a microwave and a magnetic field to convert the processing gas into plasma. Furthermore, the present invention is not limited to the film forming process, and may be applied when etching or ashing is performed.
[0036]
【The invention's effect】
According to the present invention, the uniformity of the high-frequency electric field strength distribution is high, and hence the plasma density is high in the plane parallel to the substrate. As a result, the substrate can be subjected to a highly uniform plasma treatment.
[0037]
[Brief description of the drawings]
FIG. 1 is a longitudinal side view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional plan view showing a modification of the embodiment of FIG.
FIG. 3 is an explanatory diagram showing a main part of the embodiment of FIG. 2;
4 is a cross-sectional view showing a modification of the electromagnetic wave absorber used in the embodiment of FIG.
FIG. 5 is a cross-sectional plan view showing another modification of the embodiment of FIG. 1;
6 is a characteristic diagram showing an experimental result of the embodiment of FIG. 2; FIG.
7 is a characteristic diagram showing an experimental result of the embodiment of FIG. 2; FIG.
FIG. 8 is a characteristic diagram showing experimental results when no electromagnetic wave absorber is used.
FIG. 9 is a longitudinal side view showing another embodiment of the present invention.
10 is a plan view showing a conductor used in the embodiment of FIG. 9. FIG.
11 is a plan view showing a modification of the conductor used in the embodiment of FIG. 9. FIG.
FIG. 12 is an explanatory diagram showing an example of a positional relationship between a conductor and a plasma emission region when a conductor is used.
FIG. 13 is a longitudinal side view showing still another embodiment of the present invention.
14 is a bottom view of the conductor (gas supply unit) used in the embodiment of FIG. 13 as viewed from below.
FIG. 15 is a plan view showing a conductor according to still another embodiment of the present invention.
16 is a plan view showing a modification of the conductor shown in FIG. 15. FIG.
FIG. 17 is a schematic view showing a conventional plasma processing apparatus.
[Explanation of symbols]
1 Vacuum container
2 mounting table
W Semiconductor wafer
3 Microwave transmission window
33, 35 Waveguide
37 Microwave power supply
4 Electromagnetic wave absorber
41 Space
51 First conductor
52 Second conductor
6 Gas supply section
61 Circular part (first conductor)
62 Ring-shaped part (second conductor)

Claims

A high frequency for plasma generation is supplied from a high frequency power supply unit to the vacuum vessel through a planar antenna and a high frequency transmission window, and the processing gas supplied into the vacuum vessel is turned into plasma by high frequency energy, and the plasma is used to generate a vacuum vessel. In a plasma processing apparatus for processing a substrate mounted on an internal mounting table,
An electromagnetic wave absorber is provided so as to surround the side periphery of the region from the surface on the vacuum atmosphere side of the high-frequency transmission window to the antenna,
The plasma processing apparatus according to claim 1, wherein the electromagnetic wave absorber is divided into a plurality of parts with a space in the circumferential direction.

2. The length in the circumferential direction of each electromagnetic wave absorber and the length in the circumferential direction of the space are smaller than (1/2) λg, where λg is the wavelength of the high frequency at that portion. Plasma processing equipment.

A high frequency for plasma generation is supplied from a high frequency power supply unit to the vacuum vessel through a planar antenna and a high frequency transmission window, and the processing gas supplied into the vacuum vessel is turned into plasma by high frequency energy, and the plasma is used to generate a vacuum vessel. In a plasma processing apparatus for processing a substrate mounted on an internal mounting table,
An electromagnetic wave absorber is provided so as to surround the side periphery of the region from the surface on the vacuum atmosphere side of the high-frequency transmission window to the antenna,
2. The plasma processing apparatus according to claim 1, wherein the electromagnetic wave absorber has a convex shape inward or a polygon inwardly convex when viewed in cross section.

A high frequency for plasma generation is supplied from a high frequency power supply unit to the vacuum vessel through a planar antenna and a high frequency transmission window, and the processing gas supplied into the vacuum vessel is turned into plasma by high frequency energy, and the plasma is used to generate a vacuum vessel. In a plasma processing apparatus for processing a substrate mounted on an internal mounting table,
The high-frequency transmission window and the area up to the antenna-side surface of the high frequency transmitting window from between the plasma emission region, in order to suppress the occurrence of standing waves, a plurality of regions and in the direction orthogonal direction of propagation of the high frequency of a conductor is divided into,
The plasma processing apparatus, wherein an end of the conductor on the mounting table side is exposed from the high-frequency transmission window and bites into a plasma emission region.

5. The plasma processing apparatus according to claim 4, wherein the amount of biting into the plasma emission region by the end portion of the conductor is 5 mm to 10 mm.

A high frequency for plasma generation is supplied from a high frequency power supply unit to the vacuum vessel through a planar antenna and a high frequency transmission window, and the processing gas supplied into the vacuum vessel is turned into plasma by high frequency energy, and the plasma is used to generate a vacuum vessel. In a plasma processing apparatus for processing a substrate mounted on an internal mounting table,
The region from the high-frequency transmission window and the plasma emission region to the antenna-side surface of the high-frequency transmission window is divided into a high-frequency propagation direction by a conductor in order to suppress the occurrence of standing waves. ,
The conductor includes a first conductor formed in a circular or ring shape substantially centered on the center axis of the mounting table, and a plurality of conductor conductors extending radially in order to divide the transmission window in the circumferential direction. A plasma processing apparatus comprising: a conductor provided;

7. The plasma processing apparatus according to claim 6, wherein a ring-shaped second conductor provided concentrically with the first conductor is provided outside the first conductor.

8. The plasma processing apparatus according to claim 6, wherein the inner diameter R1 of the first conductor is (1/2) λ ≦ R1 <λ, where λ is a wavelength of a high frequency.

9. The plasma processing apparatus according to claim 7, wherein the distance R2 between the conductors adjacent to each other in the radial direction is (1/2) λ ≦ R2 <λ, where λ is the wavelength of the high frequency.