JP4064557B2

JP4064557B2 - Substrate removal control method for vacuum processing apparatus

Info

Publication number: JP4064557B2
Application number: JP193199A
Authority: JP
Inventors: 出松田; 秀夫原口
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1999-01-07
Filing date: 1999-01-07
Publication date: 2008-03-19
Anticipated expiration: 2019-01-07
Also published as: JP2000200825A

Description

【０００１】
【発明の属する技術分野】
本発明は、半導体素子、液晶ディスプレイパネル或いは太陽電池などの製造に際して、被処理基板にドライエッチング、ＣＶＤまたはスパッタなどの表面処理を施すのに使用される真空処理装置において、表面処理が終了したときに基板保持台上に静電吸着している被処理基板を基板保持台から剥がして取り外す制御方法およびその基板取り外し制御方法に関するものである。
【０００２】
【従来の技術】
近年、プラズマ処理装置では、デバイスの高機能化とその処理コストの低減のために、高精度化、高速化、大面積化および低ダメージ化を実現するための取り組みが盛んに行われている。なかでも、成膜においては基板内の膜質の均一化を得るために、また、微細加工に用いられるドライエッチングにおいては寸法精度の確保のために、それぞれ被処理基板の温度をその面内全体にわたり均一に、且つ精密に制御することが特に要求されている。この基板温度を制御する手段として、ヘリウムガスなどの不活性の伝熱ガスを利用したプラズマ処理装置が使用され始めている（特開平4 −100257号公報参照）。
【０００３】
上記プラズマ処理装置は、メカクランプ若しくは静電吸着電極を利用して被処理基板を基板保持台上に強固に保持するとともに、伝熱ガスを被処理基板と基板保持台との隙間に供給して充満させる。これにより、極めて流動性の良い伝熱ガスは、被処理基板から熱を吸収して基板保持台に対し伝熱し、基板保持台は、内部の冷却水路内を常時流れる冷却水により冷却される。そのため、被処理基板は、プラズマの熱により過熱されたり、レジストが変質して表面処理不良が発生したりするのを未然に防止されるとともに、全面の温度を均一、且つ一定に保持して良好な表面処理特性を得られるようになっている。
【０００４】
上記プラズマ処理装置では、内部に静電吸着電極が埋設された基板保持台上に載置した被処理基板を、直流電圧が印加された静電吸着電極により静電吸着して固定した状態において、被処理基板に対し通常のプラズマ処理が施される。プラズマ処理（表面処理）としては、高周波電源からの高周波電力の印加などによって真空容器内にプラズマガスを発生させて、プラズマガスの成分に応じた薄膜を形成するスパッタリング、半導体ウエハ上の半導体層をフォトレジストに従いプラズマガスによって選択的に除去することにより半導体パターンを形成するドライエッチング、ドライエッチング後に不要となったフォトレジストを除去するアッシングなどがある。
【０００５】
ところで、上記のようなプラズマ処理装置では、静電吸着電極への直流電力の供給を遮断しても、静電吸着電極の表面の絶縁層に電荷が残留し、また、場合によっては絶縁性の被処理基板に帯電電荷が残留する。このため、被処理基板が静電吸着電極に静電的に吸着した状態に保持され続けるので、被処理基板は、搬送アームなどに移載するための突き上げ機構で突き上げられた場合に、静電吸着電極から剥離することができなかったり、破損したり、飛び跳ねて次工程への搬送が不能となったりすることがある。そこで、プラズマ処理が終了した時点で、直流電源から静電吸着電極への印加電圧の極性を反転させることにより、静電吸着電極の残留電荷を打ち消したのちに、被処理基板を突き上げ機構による突き上げ力で静電吸着電極から突き上げて剥離し、次工程へ搬送するようにしている。
【０００６】
ところが、上述の静電吸着電極に印加する直流電圧の極性を反転させて除電する方式では、残留電荷を過不足なく完全に除去することが困難で、残留電荷が残ったり、逆極性に帯電させてしまったりして、被処理基板を静電吸着電極から確実に剥離できないことがある。このような状態で突き上げ機構により被処理基板を突き上げてしまうと、被処理基板には、損傷、次工程への搬送不能、搬送姿勢の不良、脱落および次工程への受渡し不能といった搬送トラブルが発生することがあり、信頼性に欠ける。
【０００７】
そこで、本出願人は、表面処理済みの基板を、静電吸着電極に対する静電吸着力の残留状態に応じて適時に無理なく突き上げて静電吸着電極からスムーズに剥離させることのできる基板の取り扱い方法を先に提案している（特願平10−61318 号) 。このプラズマ処理装置における基板の取り扱い方法について、図２を参照しながら簡単に説明する。なお、このプラズマ処理装置の詳細については、図１に基づく本発明の説明において後述する。すなわち、図２において符号を付しながら説明をしない部材などについては、図１において詳細に説明する。
【０００８】
基板保持台３上に載置された被処理基板４は、基板保持台３内に埋設された静電吸着電極を兼ねる一対の内部電極７Ａ，７Ｂに正極および負極の直流電源８，９から直流電圧が印加されることにより、基板保持台３の上面に静電吸着して保持され、この状態で表面処理される。被処理基板４の表面処理が終了したのちに、内部電極７Ａ，７Ｂに対する直流電源８，９からの電力供給が停止したときに、被処理基板４は、自体のプラズマからの帯電および基板保持台３の絶縁層表面との間に存在する残留電荷のために、静電的に基板保持台３に吸着されている。
【０００９】
ここで、被処理基板４に対し搬送するために突き上げ機構１９で突き上げて基板保持台３から剥離しようとすると、被処理基板４の搬送トラブルや破損を招いてしまう。
【００１０】
そこで、被処理基板４は、以下のような工程を経て取り外す。すなわち、被処理基板４の表面処理が終了して基板保持台３に吸着している被処理基板４を突き上げ機構１９により突き上げたときに、検出手段２０は、突き上げ機構１９の先端が被処理基板４に接触した時点で、静電吸着が生じていない状態において突き上げ機構１９に加わる外力としての初期設定値以上の力を検出する。ここで、検出手段２０は、突き上げ機構１９の駆動力伝達軸線Ｘと一軸上に固定されているため、吸着力を含む全ての荷重を確実に測定することができる。そのため、検出手段２０は、上述の外力である初期設定値をオフセットすることにより、被処理基板４と基板保持台３との静電吸着力のみを極めて正確に測定する。
【００１１】
制御手段２１は、検出手段２０が検出した静電吸着力が所定値以上であると内蔵の判定部２１ｂが判別した場合に、突き上げ機構１９の駆動源である駆動手段２３を制御して、突き上げ機構１９による被処理基板４への突き上げ力が被処理基板４の材質の剪断応力限界に達する以前の時点で、突き上げ動作を停止させたのち、突き上げ機構１９を一旦下降させ、被処理基板４の破損を未然に防止する。
【００１２】
続いて、制御手段２１は、検出手段２０の検出値の静電吸着力が所定値以上であると判定部２１ｂが判別する限り、突き上げ機構１９に対し被処理基板４を突き上げたのちに下降させる動作を繰り返すよう制御する。これにより、被処理基板４は、突き上げ機構１９で断続的に突き上げられる部分から徐々に基板保持台３に対し剥離されていき、被処理基板４と基板保持台３との接触面積が徐々に減少していくのに伴って、これらの間の残留電荷が伝熱ガスを媒体として電気的に中和されていき、残留電荷が減少していく。
【００１３】
静電吸着力が被処理基板４の剪断応力よりも十分に小さくなったと判定部２１ｂが判別したときに、制御手段２１は、突き上げによって被処理基板４が突き上げ機構１９に対し位置ずれが生じない範囲内において最も速い上昇速度で突き上げ機構１９を駆動させ、被処理基板４を基板保持台３から剥離して外部に搬送させる。
【００１４】
【発明が解決しようとする課題】
上記のプラズマ処理装置における被処理基板４の取り外し方法は、被処理基板４を突き上げ機構１９により突き上げる際に、被処理基板４の基板保持台３への静電吸着力に関するデータを検出手段２０などで検出し、静電吸着力が所定値以上である場合に突き上げ機構１９による突き上げ動作を規制しているので、被処理基板４を吸着力の残留状態に応じて基板保持台３から適時に無理なく突き上げて剥離でき、被処理基板４の破損や搬送トラブルなどを確実に防止できる効果を奏するものである。ところが、実用化に際しては、なお解消しなければならない問題が残存している。すなわち、被処理基板４の基板保持台３に対する静電吸着力は、被処理基板４の処理条件の相違によって強く残留する場合があり、そのような場合、上記の被処理基板４の取り外し方法では、突き上げ機構１９の昇降動作の繰り返しによる被処理基板４への断続的な突き上げ動作を継続して行わなければならず、被処理基板４を基板保持台３から剥離するまでに相当の時間を必要とし、生産性が低下してしまう。
【００１５】
そこで本発明は、基板保持台に静電吸着している被処理基板を、これの破損や搬送トラブルを防止しながら安定、且つ極めて迅速に基板保持台から剥離して取り外すことのできる基板取り外し制御方法を提供することを目的とするものである。
【００１６】
【課題を解決するための手段】
上記目的を達成するために、本願の第１発明は、真空容器内の基板保持台上に保持された被処理基板と前記基板保持台との間に基板温度制御用の伝熱ガスを供給しながら前記被処理基板に対し表面処理を行ったのち、その表面処理に伴って前記被処理基板に生じた帯電による前記被処理基板と前記基板保持台との静電吸着力を、前記被処理基板を突き上げた時の突き上げ負荷に基づいて検出し、その検出値が所定値以上であるとき、突き上げ力が前記被処理基板の剪断応力限界に達する以前に突き上げ動作を停止するとともに、前記伝熱ガスを前記被処理基板と前記基板保持台の間に再度供給して所定の圧力としたのち、前記突き上げ力と前記伝熱ガスの圧力とを前記検出値に基づきフィードバック制御して前記被処理基板を前記基板保持台から剥離させる真空処理装置の基板取り外し制御方法であって、検出値の静電吸着力が所定値以上であるとき、突き上げ力が剪断応力限界以下の設定値に達した時点で突き上げ動作を停止するとともに、伝熱ガスの圧力を、前記検出値から算出した値に調圧するようにしたことを特徴とする。
【００１７】
この基板取り外し制御方法では、被処理基板の突き上げ負荷に基づいて被処理基板と基板保持台との静電吸着力を検出して、その検出値が所定値以上であるときに、突き上げ力が被処理基板の剪断応力限界に達する以前に突き上げ動作を停止させて、被処理基板と基板保持台との隙間に再び伝熱ガスを供給して所定の圧力に調圧している。それにより、流動性が極めて良好な伝熱ガスが被処理基板と基板保持台との隙間に流入して、被処理基板の裏面全体を伝熱ガスの圧力による被処理基板を破損させない押圧力で均等に押すことと同様の動作となる。そのため、被処理基板には、これの中央部のみを断続的に突き上げる場合に比較して突き上げ力が格段に効果的、且つ効率的に作用するとともに、基板保持台と被処理基板との間の残留電荷が圧力の高い伝熱ガスを媒体として電気的に速やかに中和される。この結果、被処理基板と基板保持台との間の静電吸着力が一挙に減少するので、被処理基板を極めて迅速、且つ円滑に基板保持台から剥離させて、トラブルなく安定に次工程に搬送でき、スループットの向上が可能となる。
【００１９】
また、伝熱ガスの圧力を、被処理基板を破損させない範囲内において可及的に大きく設定できるので、被処理基板の基板保持台からの剥離を効果的に行え、迅速に剥離できる。
【００２０】
本願の第２発明は、真空容器内の基板保持台上に保持された被処理基板と前記基板保持台との間に基板温度制御用の伝熱ガスを供給しながら前記被処理基板に対し表面処理を行ったのち、その表面処理に伴って前記被処理基板に生じた帯電による前記被処理基板と前記基板保持台との静電吸着力を、前記被処理基板を突き上げた時の突き上げ負荷に基づいて検出し、その検出値が所定値以上であるとき、突き上げ力が前記被処理基板の剪断応力限界に達する以前に突き上げ動作を停止するとともに、前記伝熱ガスを前記被処理基板と前記基板保持台の間に再度供給して所定の圧力としたのち、前記突き上げ力と前記伝熱ガスの圧力とを前記検出値に基づきフィードバック制御して前記被処理基板を前記基板保持台から剥離させる真空処理装置の基板取り外し制御方法であって、被処理基板を突き上げた時の突き上げ負荷に基づいて検出した検出値が、静電吸着が生じていない状態で突き上げ機構に加わる外力に対応した初期設定値を超えた時点で、伝熱ガスの供給を開始するとともに、前記伝熱ガスの圧力を前記検出値と前記初期設定値の差の圧力に調圧するようにしたことを特徴とする。
【００２１】
これにより、被処理基板と基板保持台との静電吸着力を可及的早期において効果的に減少させることができるから、被処理基板の基板保持台からの剥離を一層迅速に行うことが可能となる。
【００２４】
【発明の実施の形態】
以下、本発明の好ましい実施の形態について図面を参照しながら説明する。図１は本発明の一実施の形態に係る真空処理装置の断面構成図を示し、同図において、図２と同一若しくは同等のものには同一の符号を付してある。この真空処理装置が図２の従来装置に対し相違するのは、構成上において、ガス圧力調整機構１２における圧力測定器１２ａおよび圧力調整バルブ１２ｂとガス供給機構１１の流量コントローラ１１ａとにそれぞれ接続した基板冷却制御部２８を新たに設けて、この基板冷却制御部２８に制御手段２１を接続した点のみであり、この構成の詳細については後述する。
【００２５】
図１には、シリコンウエハを被処理基板４として、これに反応性イオンエッチング型のプラズマドライエッチングを行う真空処理装置を例示してある。真空容器１は、内部を真空に排気するための真空排気手段２と、反応ガスを内部に導入するための反応ガス供給手段１３とを備えている。真空容器１の内部には被処理基板４を上面に載置して保持する基板保持台３が設けられ、真空容器１の外部には、基板保持台３が保持している被処理基板４をそれの表面処理後に突き上げて基板保持台３から剥離させるための突き上げ機構１９と、この突き上げ機構１９が被処理基板４を突き上げる際の被処理基板４の基板保持台３に対する静電吸着力に関するデータを突き上げ機構１９の突き上げ負荷に基づいて検出する検出手段２０と、この検出されたデータからその時の静電吸着力が所定値以上であると内蔵の判定部２１ｂが判別しているときに、突き上げ機構１９の突き上げ動作を規制するとともに基板冷却制御部２８に対し検出手段２０の検出データに対応するデータをを出力する制御手段２１とを備えている。
【００２６】
上記基板保持台３は、静電吸着型のものであって、例えば厚さが５ｍｍ程度のアルミナ誘電体部２９と、内部に図示しない冷却水路を有したアルミニウム製のベース部３０とで構成され、アルミナ誘電体部２９の表面から500 μｍの内部に、タングステンからなる一対の静電吸着用を兼ねる下部電極である内部電極７Ａ，７Ｂが内蔵されている。一対の内部電極７Ａ，７Ｂには、対応する正極の直流電源８および負極の直流電源９からそれぞれ個別の高周波フイルタ１０を介して正、負電圧が印加されるようになっている。正極および負極の直流電圧印加回路の高周波フイルタ１０よりも内部電極７Ａ，７Ｂ側の部分には、13.56 ＭＨｚの高周波電源１４がそれぞれ個別の直流カット用コンデンサ１７を介して接続されており、前記一対の内部電極７Ａ，７Ｂにコンデンサ１７を介して高周波電力を印加できるようになっている。真空容器１内の上部には基板保持台３の内部電極７Ａ，７Ｂと対向する上部電極１８が設けられて接地され、この双方の電極１８，７Ａ，７Ｂ間での高周波電圧の印加により、真空容器１内に供給された反応ガスをプラズマ化する。
【００２７】
上記突き上げ機構１９は、４本の突き上げピン１９ａが基板保持台３の内部を下方から上方へ貫通できるように設けられており、通常時には突き上げピン１９ａが図示のように基板保持台３内に没しているが、処理すべき被処理基板４が搬送アームなどによって外部から真空容器１内に搬入されたときに、突き上げピン１９ａが基板保持台３の上方へ突出されて被処理基板４を受け取ったのちに、再び基板保持台３内に没して、被処理基板４を基板保持台３上に載置する。また、突き上げ機構１９は、基板保持台３上に静電吸着して保持された被処理基板４の表面処理が終了したときも、突き上げピン１９ａの先端が基板保持台３の上方へ突出されて被処理基板４をその裏面から突き上げ、被処理基板４を基板保持台３から剥離するよう機能する。突き上げ機構１９が基板保持台３を貫通する部分は、その外気側においてベローズ２２単体で、あるいはケーシング３１と共同で大気からシールされている。
【００２８】
上記検出手段２０は、例えばロードセルからなり、突き上げ機構１９による突き上げ負荷を静電吸着力に関するデータとして検出するために、駆動手段２３から突き上げ機構１９への突き上げ力伝達系の途中に直結状態に設けられている。
【００２９】
すなわち、検出手段２０は、突き上げ機構１９を例えば垂直線上で突き上げ動作させる駆動手段２３に対しその駆動力伝達軸線Ｘ上で直結されている。これにより、駆動手段２３による突き上げ機構１９への突き上げ動作が検出手段２０に正確に作用するので、検出手段２０は、そのときの突き上げ負荷を精度良く検出することができる。上記駆動手段としては、直動電動モータ、油圧シリンダ、エアシリンダまたはソレノイドなどの直進動作をするアクチュエータ自体、またはアクチュエータの回転動作を直進動作に変換する構造の何れをも用いることができる。
【００３０】
上記制御手段２１には、後述の初期設定値などを記憶する記憶部２１ａと、検出手段２０が検出した静電吸着力に関するデータに基づいて現時点での静電吸着力が記憶部２１ａに設定した所定値以上であるか否かを判別する判定部２１ｂとを内蔵している。この制御手段２１は、検出手段２０から取り込んだ検出データを判定部２１ｂで判別し、その判別結果に基づいて駆動手段２３をフィードバック制御する。
【００３１】
なお、静電吸着力が所定値以上であるとき、駆動力の伝達に滑りが生じて突き上げ機構１９による突き上げ動作が規制されるようなトルクリミッタを用いれば、これそのものが上記の検出手段２０と判定部２１ｂとの両機能を兼ね備えた制御手段となり、構成を簡略化できる。
【００３２】
被処理基板４と基板保持台３との隙間には、ガス供給源（図示せず）から伝熱ガス供給機構（伝熱ガス供給手段）１１を介して、例えばヘリウムガスのような伝熱ガスが供給される。この伝熱ガス供給機構１１は流量コントローラ１１ａおよびバルブ１１ｂなどにより構成されている。このガス供給機構１１に対応して、被処理基板４と基板保持台３との間の伝熱ガスの圧力を監視して制御するためのガス圧力調整機構１２が設けられており、このガス圧力調整機構１２は、上述の圧力測定器１２ａおよび圧力調整バルブ１２ｂなどにより構成されている。なお、真空容器１には、基板保持台３などの残留電荷を除去して次に搬入される被処理基板４の表面処理に備えるために、紫外線ランプ３２および石英ガラス３３からなる紫外線照射手段が設けられている。
【００３３】
つぎに、上記真空処理装置の作用について説明する。外部から真空容器１の内部に搬入された被処理基板４が、突き上げ機構１９の突き上げピン１９ａの上昇および下降によって基板保持台３の上面に載置されると、一対の内部電極７Ａ，７Ｂには直流電源８，９から高周波フイルタ１０を介して正負の直流電圧1.0 ｋＶが印加される。これにより、被処理基板４は基板保持台３の上面に静電吸着して強固に保持される。一方、真空容器１の内部は真空排気手段２により真空排気される。
【００３４】
つぎに、被処理基板４と基板保持台３との隙間には、伝熱ガス供給機構１１によって伝熱ガスを10ｃｃ／ｍｉｎで導入されるとともに、ガス圧力調整機構１２によって10Ｔｏｒｒに調圧される。さらに、真空容器１内には、反応ガス供給手段１３によって反応ガスであるＣＦ₄を3010ｃｃ／ｍｉｎと、Ｏ₂ガスを５ｃｃ／ｍｉｎとが同時に導入されるとともに、200 Ｔｏｒｒに調圧される。この状態において、一対の内部電極７Ａ，７Ｂには、高周波電源１４から高周波電力を２分岐させたのちに直流カット用コンデンサ１７を通して供給される。これにより、一対の内部電極７Ａ，７Ｂと上部電極１８との間にはプラズマが発生して、被処理基板４に対して伝熱ガスにより効率良く冷却しながら所望の表面処理（この実施の形態ではドライエッチング）が施される。
【００３５】
被処理基板４の表面処理が終了すると、高周波電力、反応ガスおよび伝熱ガスの供給をそれぞれ停止したのちに、真空排気手段２によって真空容器１の内部を真空排気しながら直流電源８，９の出力を停止する。この表面処理が終了した時点では、被処理基板４自体のプラズマからの帯電や被処理基板４と基板保持台３の絶縁層表面との間に存在する残留電荷により、被処理基板４が基板保持台３に対し静電的に吸着している。したがって、この状態で被処理基板４を突き上げ機構１９で突き上げて基板保持台３から強制的に剥離しようとすると、被処理基板４の搬送トラブルや破損を起こしてしまう。
【００３６】
そこで、残留電荷による静電吸着を解消する工程をつぎのように行う。先ず、静電吸着が発生しない状態において突き上げ機構１９に加わる外力を測定して、そのデータを初期設定値として制御手段２１の記憶部２１ａに予め記憶しておく。この測定は以下のようにして行う。すなわち、基板保持台３上に単に載置した被処理基板４を突き上げ機構１９の突き上げピン１９ａで突き上げると、検出手段２０には、真空容器１側が真空であることから大気圧による押し上げ力と、ベローズ２２の引っ張りばねによる押し上げ力と、被処理基板４の重量による押し下げ力との再現性のある外力が突き上げ機構１９を通じて加わる。この検出手段２０が検出する外力の検出データは記憶部２１ａに初期設定値として予め設定される。この記憶した初期設定値は、再現性が高いため、突き上げ機構１９を解体および再組み立てするまで変更する必要がない。
【００３７】
そして、実稼働時において、被処理基板４の表面処理が終了すると、制御手段２１により駆動手段２３が制御されて突き上げ機構１９の突き上げピン１９ａが上昇し、基板保持台３に静電吸着している被処理基板４に対し突き上げ機構１９の突き上げピン１９ａの先端が接触したときに、検出手段２０は初期設定値以上の力を検出する。ここで、検出手段２０は、突き上げ機構１９の駆動力伝達軸線Ｘと一軸上に設けられているため、静電吸着力を含む全ての外力を確実に測定できるので、初期設定値をオフセットしてやることにより、静電吸着力のみを極めて正確に測定する。
【００３８】
また、制御手段２１の記憶部２１ａには、被処理基板４を突き上げ機構１９による突き上げ力によって破断しないための剪断応力限界値が予め設定記憶されている。実測値を示すと、ベローズ２２に加わる大気圧の力が７ｋｇｆ、突き上げ機構１９の突き上げピン１９ａの先端が被処理基板４に接触したときのベローズ２２の引っ張りばね力が1.6 ｋｇｆ、被処理基板４の重量が0.1 ｋｇｆであったので、初期設定値を8.5 ｋｇｆに設定した。この初期設定値に20ｋｇｆを加算した28.5ｋｇｆを剪断応力限界値として設定した。
【００３９】
したがって、制御手段２１は、検出手段２０による検出データが剪断応力限界に近づく値、例えば20ｋｇｆに達したと判定部２１ｂが判別した時点で、駆動手段２３を駆動制御して突き上げ機構１９による突き上げ動作を停止させたのち、突き上げ機構１９を一旦下降させる。このとき、制御手段２１は検出手段２０による検出データを基板冷却制御部２８に対し出力し、基板冷却制御部２８は、ガス供給機構１１の流量コントローラ１１ａを制御して被処理基板４と基板保持台３との隙間に再び伝熱ガスを供給させるとともに、検出データに基づき算出した設定値に対応してガス圧力調整機構１２の圧力測定器１２ａと圧力調整バルブ１２ｂとを制御し、伝熱ガスの圧力を上記の設定値に調圧する。
【００４０】
例えば、被処理基板４の裏面の表面積が15²×3.14ｃｍ²である場合、いま、被処理基板４の剪断応力限界以下の設定値とした20ｋｇｆを上記表面積で除算すると、単位面積当たりの静電吸着力を算出できる。ここで、１ｋｇｆ／ｃｍ²＝760 Ｔｏｒｒであるから、20ｋｇｆ／（15²×3.14ｃｍ²）×７６０＝21.5Ｔｏｒｒとなる。すなわち、基板冷却制御部２８は、圧力測定器１２ａの測定値が上記の検出データに基づき算出した21.5Ｔｏｒｒの圧力値になるよう圧力調整バルブ１２ｂおよび流量コントローラ１１ａを制御する。これにより、被処理基板４と基板保持台３との隙間に供給された伝熱ガスの圧力は21.5Ｔｏｒｒに調圧される。
【００４１】
上記状態において、制御手段２１は突き上げ機構１９を再び上昇させるよう制御する。この場合は、流動性が極めて良好なヘリウムガスからなる伝熱ガスが被処理基板４と基板保持台３との隙間に流入していくので、被処理基板４の裏面全体を伝熱ガスの高い圧力による均等な押圧力で押すことと同様の動作となり、その押圧力は、被処理基板４を破損させない範囲内で可及的に大きく設定されたものである。そのため、被処理基板４には、これの中央部のみを突き上げ機構１９の突き上げピン１９ａで突き上げる場合に比較して突き上げ力が格段に効果的、且つ効率的に作用する。その上に、基板保持台３のアルミナ誘電体部２９と被処理基板４との間の残留電荷は、可及的に高圧に調圧された伝熱ガスを媒体として電気的に速やかに中和される。この結果、被処理基板４と基板保持台３との静電吸着力が一挙に減少するので、被処理基板４は極めて迅速、且つ円滑に基板保持台３から剥離されて、トラブルなく安定に次工程に搬送され、スループットの向上が可能となる。
【００４２】
これに対し、図２の真空処理装置では、制御手段２１の制御によって突き上げ機構１９が上昇および下降を繰り返して被処理基板４を突き上げピン１９ａで断続的に突き上げるだけであるから、基板保持台３に残留電荷で吸着保持されている被処理基板４は、突き上げ機構１９の突き上げピン１９ａが接触する部分を基板保持台３から少しずつ剥離されたのちに、この剥離が徐々に周囲に拡げられていき、被処理基板４の基板保持台３に対する接触面積も徐々に減少していく。したがって、被処理基板４は無理な突き上げ力を受けることなく確実に剥離されるものの、剥離され終わるまでに相当の時間を要することになる。
【００４３】
また、上記実施の形態では、検出手段２０による検出データが剪断応力限界に近い所定値に達したと判定部２１ｂが判別した時点で、伝熱ガスの供給を開始して、その伝熱ガスの圧力を、上記検出データに基づいて基板冷却制御部２８が算出した設定値になるよう制御するようにしたが、検出手段２０による検出データが初期設定値つまり静電吸着力が発生していないときの外力の値を超えた時点から、伝熱ガスの供給を開始して、その伝熱ガスの圧力を、検出データと初期設定値との差に相当する値になるようフィードバック制御するようにしてもよい。この場合には、被処理基板４と基板保持台３との静電吸着力を可及的早期の時点で効果的に減少させて、被処理基板４の基板保持台３からの剥離を一層迅速に行うことが可能となる。
【００４４】
なお、上記実施の形態では、真空処理装置として、反応性イオンエッチング型のドライエッチング装置を例示して説明したが、プラズマの発生手段はこれに限られるものではなく、誘導結合型、ＥＣＲ型、ヘリコン型または表面波型などのプラズマ発生手段を備えたものにも適用できる。
【００４５】
また、ドライエッチング装置に代えて、プラズマＣＶＤ装置やスパッタリング装置あるいはアッシング装置などにも本発明を有効に適用できる。さらに、被処理基板４を静電吸着する基板保持台３の静電吸着電極は、正極および負極を用いる双極型のものを例示したが、これに代えて、単極型のものを用いることもできる。
【００４６】
また、伝熱ガスとしては、ヘリウムガス以外の不活性ガス或いは他のガスを用いることもできる。さらに、伝熱ガスの配管系統は上記実施の形態の系統に限られるものではなく、被処理基板４と基板保持台３との間にガスを供給できる配管系統であればよい。さらにまた、上記実施の形態では、静電吸着型の基板保持台３を用いた場合について説明したが、接地或いは高周波電力が印加される基板保持台であっても、絶縁材料の被処理基板の場合には特に残留電荷による吸着に起因する搬送トラブルが発生するので、このような場合にも本発明を適用して同様の効果を得ることができる。
【００４７】
【発明の効果】
以上のように、本発明の真空処理装置の基板取り外し制御方法によれば、被処理基板を極めて迅速、且つ円滑に基板保持台から剥離させ、トラブルなく安定に次工程に搬送できる。
【図面の簡単な説明】
【図１】本発明の基板取り外し制御方法を適用できる真空処理装置を示す断面構成図。
【図２】従来の真空処理装置を示す断面構成図。
【符号の説明】
１真空容器
２真空排気手段
３基板保持台
４被処理基板
１１伝熱ガス供給手段
１２ガス圧力調整機構
１３反応ガス供給手段
１９突き上げ機構
２０検出手段
２１制御手段
２８基板冷却制御部
Ｘ駆動力伝達軸線（突き上げ力伝達部）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum processing apparatus used for performing surface treatment such as dry etching, CVD or sputtering on a substrate to be processed when manufacturing a semiconductor element, a liquid crystal display panel, or a solar cell. Control method for removing a substrate to be processed that is electrostatically adsorbed on a substrate holding table from the substrate holding table, and a method for controlling the removal of the substrate To the law It is related.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in plasma processing apparatuses, efforts have been actively made to achieve high accuracy, high speed, large area, and low damage in order to increase device functionality and reduce processing costs. In particular, in order to obtain uniform film quality in the substrate during film formation, and in order to ensure dimensional accuracy in dry etching used for microfabrication, the temperature of the substrate to be processed is varied over the entire surface. There is a particular demand for uniform and precise control. As a means for controlling the substrate temperature, a plasma processing apparatus using an inert heat transfer gas such as helium gas has begun to be used (see Japanese Patent Laid-Open No. 4-100257).
[0003]
The plasma processing apparatus firmly holds the substrate to be processed on the substrate holding table using a mechanical clamp or an electrostatic chucking electrode, and supplies heat transfer gas to the gap between the substrate to be processed and the substrate holding table. To charge. Thereby, the heat transfer gas having extremely good fluidity absorbs heat from the substrate to be processed and transfers the heat to the substrate holding table, and the substrate holding table is cooled by the cooling water constantly flowing in the internal cooling water channel. Therefore, it is possible to prevent the substrate to be processed from being overheated by the heat of the plasma or causing the resist to change in quality and causing a defective surface treatment, and to maintain a uniform and constant temperature on the entire surface. Surface treatment characteristics can be obtained.
[0004]
In the plasma processing apparatus, in a state where the substrate to be processed placed on the substrate holding table in which the electrostatic adsorption electrode is embedded is electrostatically adsorbed and fixed by the electrostatic adsorption electrode to which a DC voltage is applied. A normal plasma process is performed on the substrate to be processed. As plasma treatment (surface treatment), plasma gas is generated in a vacuum vessel by applying high-frequency power from a high-frequency power source, and a semiconductor layer on a semiconductor wafer is formed by sputtering to form a thin film according to the plasma gas component. There are dry etching for forming a semiconductor pattern by selectively removing with a plasma gas according to a photoresist, ashing for removing a photoresist that is no longer necessary after dry etching, and the like.
[0005]
By the way, in the plasma processing apparatus as described above, even if the supply of DC power to the electrostatic chucking electrode is interrupted, electric charges remain on the insulating layer on the surface of the electrostatic chucking electrode. Charged charges remain on the substrate to be processed. For this reason, since the substrate to be processed continues to be held in a state of being electrostatically attracted to the electrostatic chucking electrode, the substrate to be processed is electrostatically charged when it is pushed up by a push-up mechanism for transfer to a transfer arm or the like. The adsorption electrode may not be peeled off, may be damaged, or may jump and become unable to be transferred to the next process. Therefore, when the plasma processing is completed, the polarity of the voltage applied from the DC power supply to the electrostatic chucking electrode is reversed to cancel the residual charge of the electrostatic chucking electrode, and then the substrate to be processed is pushed up by the thrusting mechanism. It is pushed up from the electrostatic chucking electrode by force and peeled off, and transported to the next process.
[0006]
However, it is difficult to completely remove residual charges without excess or deficiency with the above-described method of removing the charge by reversing the polarity of the DC voltage applied to the electrostatic chucking electrode. In some cases, the substrate to be processed cannot be reliably peeled off from the electrostatic chucking electrode. If the substrate to be processed is pushed up by the push-up mechanism in such a state, conveyance troubles such as damage, inability to convey to the next process, poor conveyance posture, dropout and inability to deliver to the next process occur. May be unreliable.
[0007]
Therefore, the present applicant handles the substrate that can be smoothly peeled off from the electrostatic adsorption electrode by pushing the surface-treated substrate smoothly and timely according to the residual state of the electrostatic adsorption force on the electrostatic adsorption electrode. A method has been proposed previously (Japanese Patent Application No. 10-61318). A method of handling a substrate in this plasma processing apparatus will be briefly described with reference to FIG. The details of the plasma processing apparatus will be described later in the description of the present invention based on FIG. That is, members that are not described with reference numerals in FIG. 2 will be described in detail in FIG.
[0008]
The substrate 4 to be processed placed on the substrate holder 3 is connected to a pair of internal electrodes 7A and 7B that also serve as electrostatic adsorption electrodes embedded in the substrate holder 3 from the positive and negative DC power sources 8 and 9. By applying a voltage, it is electrostatically attracted and held on the upper surface of the substrate holder 3 and surface treatment is performed in this state. When the power supply from the DC power supplies 8 and 9 to the internal electrodes 7A and 7B is stopped after the surface treatment of the substrate to be processed 4 is finished, the substrate to be processed 4 is charged from its own plasma and the substrate holding base. 3 is electrostatically attracted to the substrate holder 3 because of the residual charges existing between the surfaces of the insulating layers 3.
[0009]
Here, if the push-up mechanism 19 pushes up and peels from the substrate holding table 3 in order to transport the substrate to be processed 4, a trouble or breakage of the substrate to be processed 4 is caused.
[0010]
Therefore, the substrate 4 to be processed is removed through the following steps. That is, when the surface of the substrate to be processed 4 is finished and the substrate to be processed 4 adsorbed on the substrate holder 3 is pushed up by the push-up mechanism 19, the detection means 20 has the tip of the push-up mechanism 19 at the tip of the substrate to be processed. At the time of contact with 4, a force equal to or greater than an initial set value is detected as an external force applied to the push-up mechanism 19 in a state where no electrostatic attraction occurs. Here, since the detection means 20 is fixed on the same axis as the driving force transmission axis X of the push-up mechanism 19, all the loads including the suction force can be reliably measured. Therefore, the detection means 20 measures only the electrostatic attraction force between the substrate to be processed 4 and the substrate holder 3 very accurately by offsetting the initial set value which is the above external force.
[0011]
When the built-in determination unit 21b determines that the electrostatic attraction force detected by the detection unit 20 is greater than or equal to a predetermined value, the control unit 21 controls the drive unit 23 that is a drive source of the push-up mechanism 19 to push up Before the push-up force on the substrate 4 to be processed by the mechanism 19 reaches the shear stress limit of the material of the substrate 4 to be processed, the push-up operation is stopped, and then the push-up mechanism 19 is temporarily lowered to remove the substrate 4 to be processed. Prevent damage in advance.
[0012]
Subsequently, as long as the determination unit 21b determines that the electrostatic attraction force of the detection value of the detection unit 20 is equal to or greater than a predetermined value, the control unit 21 pushes down the substrate 4 to be pushed up with respect to the push-up mechanism 19 and then lowers it. Control to repeat the operation. As a result, the substrate to be processed 4 is gradually peeled from the substrate holding base 3 from the portion that is intermittently pushed up by the push-up mechanism 19, and the contact area between the substrate 4 to be processed and the substrate holding base 3 is gradually reduced. As the process proceeds, the residual charge between them is electrically neutralized using the heat transfer gas as a medium, and the residual charge decreases.
[0013]
When the determination unit 21b determines that the electrostatic attraction force is sufficiently smaller than the shearing stress of the substrate 4 to be processed, the control unit 21 causes the substrate 4 to be moved without being displaced relative to the push-up mechanism 19 by the push-up. The push-up mechanism 19 is driven at the fastest rising speed within the range, and the substrate 4 to be processed is peeled off from the substrate holder 3 and transported to the outside.
[0014]
[Problems to be solved by the invention]
The method for removing the substrate 4 to be processed in the plasma processing apparatus described above is based on the detection means 20 and the like regarding the electrostatic attraction force of the substrate 4 to the substrate holder 3 when the substrate 4 is pushed up by the push-up mechanism 19. When the electrostatic attraction force is equal to or greater than a predetermined value, the push-up operation by the push-up mechanism 19 is restricted, so that the substrate 4 to be processed is forced from the substrate holder 3 in a timely manner according to the remaining state of the suction force. Thus, the substrate can be pushed up and peeled off, and the substrate 4 to be processed can be reliably prevented from being damaged or transported. However, problems still need to be solved in practical use. That is, the electrostatic attraction force of the substrate to be processed 4 with respect to the substrate holding table 3 may remain strongly due to the difference in the processing conditions of the substrate to be processed 4. The intermittent push-up operation to the substrate 4 to be processed by repeating the raising and lowering operation of the push-up mechanism 19 must be continuously performed, and a considerable time is required until the substrate 4 to be processed is peeled from the substrate holder 3. And productivity will be reduced.
[0015]
Therefore, the present invention provides a substrate removal control that allows a substrate to be processed that is electrostatically adsorbed to a substrate holder to be detached and removed from the substrate holder in a stable and extremely rapid manner while preventing damage and transport trouble. Direction The law It is intended to provide.
[0016]
[Means for Solving the Problems]
To achieve the above objective, 1st invention of this application After surface treatment is performed on the substrate to be processed while supplying a heat transfer gas for controlling the substrate temperature between the substrate to be processed held on the substrate holding table in the vacuum vessel and the substrate holding table. , Detecting the electrostatic adsorption force between the substrate to be processed and the substrate holder due to the charge generated on the substrate to be processed in accordance with the surface treatment based on the pushing load when the substrate to be processed is pushed up, When the detected value is equal to or greater than a predetermined value, the push-up operation is stopped before the push-up force reaches the shear stress limit of the substrate to be processed, and the heat transfer gas is passed between the substrate to be processed and the substrate holder. After supplying again to a predetermined pressure, the push-up force and the pressure of the heat transfer gas are feedback-controlled based on the detected value to peel off the substrate to be processed from the substrate holder. In the substrate removal control method of the vacuum processing apparatus, when the electrostatic adsorption force of the detected value is equal to or greater than a predetermined value, the push-up operation is stopped when the push-up force reaches a set value below the shear stress limit, and the transmission is stopped. The pressure of the hot gas was adjusted to the value calculated from the detected value. It is characterized by that.
[0017]
In this substrate removal control method, the electrostatic attraction force between the substrate to be processed and the substrate holder is detected based on the thrust load of the substrate to be processed, and when the detected value is a predetermined value or more, the thrust force is Before reaching the shear stress limit of the processing substrate, the pushing-up operation is stopped, and the heat transfer gas is supplied again to the gap between the substrate to be processed and the substrate holder to adjust the pressure to a predetermined pressure. As a result, heat transfer gas with extremely good fluidity flows into the gap between the substrate to be processed and the substrate holder, and the entire back surface of the substrate to be processed is pressed with a pressure that does not damage the substrate to be processed due to the pressure of the heat transfer gas. The operation is the same as pressing evenly. Therefore, the push-up force acts on the substrate to be processed much more effectively and efficiently than when only the central portion of the substrate is pushed up intermittently, and between the substrate holder and the substrate to be processed. Residual charges are quickly neutralized electrically using a heat transfer gas with high pressure as a medium. As a result, the electrostatic adsorption force between the substrate to be processed and the substrate holder is reduced at a stroke, so that the substrate to be processed is peeled off from the substrate holder extremely quickly and smoothly, and can be carried on to the next process without any trouble. It can be transported and throughput can be improved.
[0019]
Also, The pressure of the heat transfer gas can be set as high as possible within the range that does not damage the substrate to be processed. Effect It can be done effectively and can be peeled off quickly.
[0020]
According to a second aspect of the present invention, the surface of the substrate to be processed is supplied to the substrate to be processed while supplying a heat transfer gas for controlling the substrate temperature between the substrate to be processed held on the substrate holder in the vacuum vessel and the substrate holder. After performing the treatment, the electrostatic adsorption force between the substrate to be processed and the substrate holding table due to the charge generated on the substrate to be processed in accordance with the surface treatment is used as a push-up load when the substrate to be processed is pushed up. When the detected value is equal to or greater than a predetermined value, the push-up operation is stopped before the push-up force reaches the shear stress limit of the substrate to be processed, and the heat transfer gas is supplied to the substrate to be processed and the substrate. After supplying again between the holding bases to a predetermined pressure, a vacuum for peeling the substrate to be processed from the substrate holding base by feedback-controlling the push-up force and the pressure of the heat transfer gas based on the detection value. Processing equipment A substrate removal control method, Supply of heat transfer gas when the detection value detected based on the thrust load when the substrate to be processed is thrust exceeds the initial set value corresponding to the external force applied to the thrust mechanism without electrostatic adsorption And adjusting the pressure of the heat transfer gas to a pressure difference between the detected value and the initial set value. It is characterized by .
[0021]
As a result, the electrostatic adsorption force between the substrate to be processed and the substrate holder can be effectively reduced as early as possible, so that the substrate to be processed can be peeled off from the substrate holder more quickly. It becomes.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional configuration diagram of a vacuum processing apparatus according to an embodiment of the present invention, in which the same or equivalent parts as in FIG. This vacuum processing apparatus is different from the conventional apparatus of FIG. 2 in that it is connected to the pressure measuring device 12a and the pressure adjusting valve 12b in the gas pressure adjusting mechanism 12 and the flow rate controller 11a of the gas supplying mechanism 11 in terms of configuration. Only the substrate cooling control unit 28 is newly provided and the control means 21 is connected to the substrate cooling control unit 28. Details of this configuration will be described later.
[0025]
FIG. 1 exemplifies a vacuum processing apparatus that uses a silicon wafer as a substrate 4 to be processed and performs reactive ion etching type plasma dry etching. The vacuum vessel 1 includes a vacuum exhaust unit 2 for exhausting the inside to a vacuum, and a reaction gas supply unit 13 for introducing a reaction gas into the interior. A substrate holding table 3 is provided inside the vacuum vessel 1 to place and hold the substrate to be processed 4 on the upper surface, and the substrate to be processed 4 held by the substrate holding table 3 is provided outside the vacuum vessel 1. A push-up mechanism 19 that pushes up after the surface treatment and separates it from the substrate holding table 3, and data relating to the electrostatic adsorption force of the substrate to be processed 4 to the substrate holding table 3 when the push-up mechanism 19 pushes up the substrate 4 to be processed. When the built-in determination unit 21b determines that the electrostatic attraction force at that time is greater than or equal to a predetermined value from the detected data, the detection unit 20 detects the movement based on the pushing load of the pushing mechanism 19. And a control unit 21 that regulates the pushing-up operation of the mechanism 19 and outputs data corresponding to the detection data of the detection unit 20 to the substrate cooling control unit 28.
[0026]
The substrate holder 3 is of an electrostatic adsorption type, and is composed of, for example, an alumina dielectric part 29 having a thickness of about 5 mm and an aluminum base part 30 having a cooling water channel (not shown) inside. In addition, internal electrodes 7A and 7B, which are a pair of lower electrodes that serve also for electrostatic attraction, are made of tungsten inside 500 μm from the surface of the alumina dielectric portion 29. Positive and negative voltages are applied to the pair of internal electrodes 7A, 7B from the corresponding positive DC power supply 8 and negative DC power supply 9 via individual high frequency filters 10, respectively. A high frequency power supply 14 of 13.56 MHz is connected to each of the internal electrodes 7A and 7B side of the high frequency filter 10 of the positive and negative DC voltage application circuits via individual DC cut capacitors 17, respectively. The high frequency power can be applied to the internal electrodes 7A and 7B via the capacitor 17. An upper electrode 18 facing the internal electrodes 7A and 7B of the substrate holding table 3 is provided at the upper part in the vacuum vessel 1 and grounded. By applying a high-frequency voltage between both the electrodes 18, 7A and 7B, a vacuum is formed. The reaction gas supplied into the container 1 is turned into plasma.
[0027]
The push-up mechanism 19 is provided so that four push-up pins 19a can penetrate the inside of the substrate holding base 3 from below to above. Normally, the push-up pins 19a are immersed in the substrate holding base 3 as shown in the figure. However, when the substrate 4 to be processed is carried into the vacuum vessel 1 from the outside by a transfer arm or the like, the push-up pin 19a protrudes above the substrate holder 3 and receives the substrate 4 to be processed. After that, the substrate 4 is again immersed in the substrate holder 3 and the substrate 4 to be processed is placed on the substrate holder 3. Further, the push-up mechanism 19 is configured such that the tip of the push-up pin 19a protrudes above the substrate holding table 3 even when the surface treatment of the substrate to be processed 4 electrostatically attracted and held on the substrate holding table 3 is completed. The substrate to be processed 4 is pushed up from its back surface and functions to peel off the substrate to be processed 4 from the substrate holder 3. The portion through which the push-up mechanism 19 penetrates the substrate holding table 3 is sealed from the atmosphere by the bellows 22 alone or jointly with the casing 31 on the outside air side.
[0028]
The detection means 20 is composed of, for example, a load cell, and is provided in a directly connected state in the middle of the thrust force transmission system from the drive means 23 to the thrust mechanism 19 in order to detect the thrust load by the thrust mechanism 19 as data on the electrostatic attraction force. It has been.
[0029]
That is, the detection means 20 is directly connected on the driving force transmission axis X with respect to the drive means 23 that causes the push-up mechanism 19 to push-up on a vertical line, for example. Thereby, the pushing-up operation to the pushing-up mechanism 19 by the drive means 23 acts on the detecting means 20 accurately, so that the detecting means 20 can accurately detect the pushing load at that time. As the drive means, any of an actuator that performs a linear motion such as a linear electric motor, a hydraulic cylinder, an air cylinder, or a solenoid, or a structure that converts a rotational motion of the actuator into a linear motion can be used.
[0030]
In the control means 21, a storage unit 21a for storing an initial setting value, which will be described later, and the electrostatic adsorption force at the present time are set in the storage unit 21a based on data on the electrostatic adsorption force detected by the detection unit 20. The determination part 21b which discriminate | determines whether it is more than predetermined value is built in. The control means 21 discriminates the detection data fetched from the detection means 20 by the determination unit 21b, and feedback-controls the drive means 23 based on the determination result.
[0031]
If a torque limiter is used that, when the electrostatic attraction force is greater than or equal to a predetermined value, causes slippage in the transmission of the driving force and restricts the push-up operation by the push-up mechanism 19, this is the same as the detection means 20 described above. It becomes a control means which has both functions with the determination part 21b, and can simplify a structure.
[0032]
In the gap between the substrate 4 to be processed and the substrate holder 3, a heat transfer gas such as helium gas is supplied from a gas supply source (not shown) via a heat transfer gas supply mechanism (heat transfer gas supply means) 11. Is supplied. The heat transfer gas supply mechanism 11 includes a flow rate controller 11a and a valve 11b. Corresponding to the gas supply mechanism 11, a gas pressure adjusting mechanism 12 for monitoring and controlling the pressure of the heat transfer gas between the substrate 4 to be processed and the substrate holding table 3 is provided. The adjustment mechanism 12 includes the pressure measuring instrument 12a and the pressure adjustment valve 12b described above. The vacuum vessel 1 is provided with ultraviolet irradiation means comprising an ultraviolet lamp 32 and quartz glass 33 in order to remove the residual charges such as the substrate holder 3 and prepare for the surface treatment of the substrate 4 to be loaded next. Is provided.
[0033]
Next, the operation of the vacuum processing apparatus will be described. When the substrate to be processed 4 carried into the vacuum vessel 1 from the outside is placed on the upper surface of the substrate holding table 3 by the raising and lowering of the push-up pin 19a of the push-up mechanism 19, the pair of internal electrodes 7A and 7B are applied. A positive and negative DC voltage of 1.0 kV is applied from the DC power sources 8 and 9 through the high frequency filter 10. As a result, the substrate to be processed 4 is electrostatically attracted to the upper surface of the substrate holding table 3 and is firmly held. On the other hand, the inside of the vacuum vessel 1 is evacuated by the evacuation means 2.
[0034]
Next, a heat transfer gas is introduced into the gap between the substrate 4 to be processed 4 and the substrate holder 3 by the heat transfer gas supply mechanism 11 at 10 cc / min, and the pressure is adjusted to 10 Torr by the gas pressure adjusting mechanism 12. . Further, in the vacuum vessel 1, CF which is a reactive gas is supplied by a reactive gas supply means 13. _Four 3010cc / min, O ₂ Gas is simultaneously introduced at 5 cc / min and the pressure is adjusted to 200 Torr. In this state, the pair of internal electrodes 7A and 7B is supplied with the high frequency power from the high frequency power supply 14 through the DC cut capacitor 17 after being branched into two branches. As a result, plasma is generated between the pair of internal electrodes 7A and 7B and the upper electrode 18, and the desired surface treatment (this embodiment) is performed while efficiently cooling the substrate 4 to be processed by the heat transfer gas. Then, dry etching) is performed.
[0035]
When the surface treatment of the substrate to be processed 4 is finished, the supply of the high frequency power, the reaction gas, and the heat transfer gas is stopped, and then the DC power sources 8 and 9 Stop output. At the time when the surface treatment is completed, the substrate 4 is held by the substrate 4 due to charging from the plasma of the substrate 4 itself or residual charges existing between the substrate 4 and the insulating layer surface of the substrate holder 3. It is electrostatically attracted to the table 3. Therefore, if the substrate to be processed 4 is pushed up by the push-up mechanism 19 in this state and forcedly peeled off from the substrate holder 3, a conveyance trouble or breakage of the substrate to be processed 4 occurs.
[0036]
Therefore, the process of eliminating the electrostatic adsorption due to the residual charge is performed as follows. First, an external force applied to the push-up mechanism 19 in a state where electrostatic attraction does not occur is measured, and the data is stored in advance in the storage unit 21a of the control means 21 as an initial set value. This measurement is performed as follows. That is, when the substrate 4 to be processed simply placed on the substrate holding table 3 is pushed up by the push-up pin 19a of the push-up mechanism 19, the detection means 20 has a push-up force due to atmospheric pressure because the vacuum container 1 side is vacuum, An external force having reproducibility of the push-up force of the bellows 22 by the tension spring and the push-down force by the weight of the substrate 4 to be processed is applied through the push-up mechanism 19. The external force detection data detected by the detection means 20 is preset in the storage unit 21a as an initial set value. Since the stored initial setting value has high reproducibility, it is not necessary to change until the push-up mechanism 19 is disassembled and reassembled.
[0037]
When the surface treatment of the substrate 4 to be processed is completed during actual operation, the drive means 23 is controlled by the control means 21 and the push-up pin 19a of the push-up mechanism 19 is lifted and electrostatically attracted to the substrate holding table 3. When the tip of the push-up pin 19a of the push-up mechanism 19 comes into contact with the substrate 4 being processed, the detection means 20 detects a force that is equal to or greater than the initial set value. Here, since the detecting means 20 is provided on the same axis as the driving force transmission axis X of the push-up mechanism 19, all external forces including the electrostatic attraction force can be reliably measured, so that the initial set value is offset. Thus, only the electrostatic adsorption force is measured very accurately.
[0038]
The storage unit 21a of the control means 21 stores in advance a shear stress limit value for preventing the substrate to be processed 4 from being broken by the push-up force by the push-up mechanism 19. When the measured value is shown, the force of the atmospheric pressure applied to the bellows 22 is 7 kgf, the tension spring force of the bellows 22 when the tip of the push-up pin 19a of the push-up mechanism 19 contacts the substrate 4 to be processed, 1.6 kgf, Was 0.1 kgf, so the initial set value was set to 8.5 kgf. 28.5 kgf obtained by adding 20 kgf to this initial set value was set as the shear stress limit value.
[0039]
Therefore, the control means 21 controls the drive means 23 to drive the push-up mechanism 19 when the determination unit 21b determines that the detection data from the detection means 20 has reached a value close to the shear stress limit, for example, 20 kgf. Is stopped, the push-up mechanism 19 is once lowered. At this time, the control unit 21 outputs detection data from the detection unit 20 to the substrate cooling control unit 28, and the substrate cooling control unit 28 controls the flow rate controller 11 a of the gas supply mechanism 11 to hold the substrate to be processed 4 and the substrate. The heat transfer gas is supplied again to the gap with the base 3, and the pressure measuring device 12a and the pressure adjustment valve 12b of the gas pressure adjusting mechanism 12 are controlled in accordance with the set value calculated based on the detection data, thereby the heat transfer gas. Is adjusted to the above set value.
[0040]
For example, the surface area of the back surface of the substrate to be processed 4 is 15 ² × 3.14cm ² In this case, the electrostatic attraction force per unit area can be calculated by dividing 20 kgf, which is a set value not more than the shear stress limit of the substrate 4 to be processed, by the surface area. Here, 1 kgf / cm ² = 760 Torr, so 20kgf / (15 ² × 3.14cm ² ) × 760 = 21.5 Torr. That is, the substrate cooling control unit 28 controls the pressure adjustment valve 12b and the flow rate controller 11a so that the measured value of the pressure measuring device 12a becomes the pressure value of 21.5 Torr calculated based on the detection data. As a result, the pressure of the heat transfer gas supplied to the gap between the substrate 4 to be processed and the substrate holder 3 is adjusted to 21.5 Torr.
[0041]
In the above state, the control means 21 controls the push-up mechanism 19 to rise again. In this case, the heat transfer gas made of helium gas having very good fluidity flows into the gap between the substrate to be processed 4 and the substrate holder 3, so that the entire back surface of the substrate to be processed 4 has a high heat transfer gas. The operation is the same as that of pressing with an equal pressing force by pressure, and the pressing force is set as large as possible within a range in which the substrate to be processed 4 is not damaged. Therefore, the push-up force acts on the substrate 4 to be processed much more effectively and efficiently than when the push-up pin 19a of the push-up mechanism 19 pushes up only the central portion thereof. In addition, the residual charge between the alumina dielectric portion 29 of the substrate holder 3 and the substrate 4 to be processed is electrically neutralized quickly using a heat transfer gas adjusted to the highest possible pressure as a medium. Is done. As a result, the electrostatic adsorption force between the substrate to be processed 4 and the substrate holding table 3 is reduced at a stroke, so that the substrate to be processed 4 is peeled off from the substrate holding table 3 very quickly and smoothly and stably without trouble. Through the process, throughput can be improved.
[0042]
On the other hand, in the vacuum processing apparatus shown in FIG. 2, the push-up mechanism 19 repeats raising and lowering by the control of the control means 21 and only pushes up the substrate 4 to be processed intermittently with the push-up pins 19a. The substrate to be processed 4 adsorbed and held by the residual charge is peeled off gradually from the substrate holding base 3 at the portion where the push-up pin 19a of the push-up mechanism 19 contacts, and then the peel is gradually spread to the periphery. Then, the contact area of the substrate 4 to be processed with respect to the substrate holding table 3 gradually decreases. Therefore, although the substrate 4 to be processed is reliably peeled without receiving an excessive pushing force, a considerable time is required until the peeling is finished.
[0043]
Moreover, in the said embodiment, when the determination part 21b discriminate | determines that the detection data by the detection means 20 reached the predetermined value near a shear stress limit, supply of heat transfer gas is started, The pressure is controlled to be the set value calculated by the substrate cooling control unit 28 based on the detection data, but the detection data by the detection means 20 is the initial set value, that is, when the electrostatic attraction force is not generated. The supply of heat transfer gas is started from the point of time when the external force exceeds the value, and feedback control is performed so that the pressure of the heat transfer gas becomes a value corresponding to the difference between the detected data and the initial set value. Also good. In this case, the electrostatic attraction force between the substrate 4 to be processed and the substrate holder 3 is effectively reduced at the earliest possible time, and the separation of the substrate 4 to be processed from the substrate holder 3 is further accelerated. Can be performed.
[0044]
In the above-described embodiment, the reactive ion etching type dry etching apparatus is exemplified as the vacuum processing apparatus. However, the plasma generation means is not limited to this, and an inductive coupling type, an ECR type, The present invention can also be applied to a device having plasma generation means such as a helicon type or a surface wave type.
[0045]
Further, the present invention can be effectively applied to a plasma CVD apparatus, a sputtering apparatus, an ashing apparatus, or the like instead of the dry etching apparatus. Further, the electrostatic chucking electrode of the substrate holder 3 that electrostatically chucks the substrate to be processed 4 is exemplified as a bipolar type using a positive electrode and a negative electrode, but a monopolar type may be used instead. it can.
[0046]
Further, as the heat transfer gas, an inert gas other than helium gas or other gas can be used. Furthermore, the piping system of the heat transfer gas is not limited to the system of the above embodiment, and any piping system that can supply gas between the substrate to be processed 4 and the substrate holder 3 may be used. Furthermore, in the above embodiment, the case where the electrostatic adsorption type substrate holder 3 is used has been described. However, even if the substrate holder is applied with grounding or high frequency power, the substrate of the insulating material to be processed is used. In such a case, a conveyance trouble due to adsorption due to residual charges occurs. In this case, the present invention can be applied to obtain the same effect.
[0047]
【The invention's effect】
As described above, according to the substrate removal control method of the vacuum processing apparatus of the present invention, , Covered The processing substrate can be peeled off from the substrate holder very quickly and smoothly, and can be transported to the next process stably without any trouble.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram showing a vacuum processing apparatus to which a substrate removal control method of the present invention can be applied.
FIG. 2 is a cross-sectional configuration diagram showing a conventional vacuum processing apparatus.
[Explanation of symbols]
1 Vacuum container
2 Vacuum exhaust means
3 Substrate holder
4 Substrate
11 Heat transfer gas supply means
12 Gas pressure adjustment mechanism
13 Reactive gas supply means
19 Pushing mechanism
20 Detection means
21 Control means
28 Substrate cooling controller
X Driving force transmission axis (push-up force transmission part)

Claims

After performing surface treatment on the substrate to be processed while supplying a heat transfer gas for substrate temperature control between the substrate to be processed held on the substrate holding table in the vacuum vessel and the substrate holding table, The electrostatic attraction force between the substrate to be processed and the substrate holder due to the charge generated on the substrate to be processed in accordance with the surface treatment is detected based on the pushing load when the substrate to be processed is pushed up, and the detection When the value is equal to or greater than a predetermined value, the pushing operation is stopped before the pushing force reaches the shear stress limit of the substrate to be processed, and the heat transfer gas is supplied again between the substrate to be processed and the substrate holder. substrate removal of predetermined After the pressure, the push-up force and vacuum processing apparatus and a pressure feedback control on the basis of the detected values Ru is peeled off the substrate to be processed from the substrate holder of the heat transfer gas and control A law,
When the electrostatic adsorption force of the detected value is equal to or greater than a predetermined value, the push-up operation is stopped when the push-up force reaches a set value below the shear stress limit, and the pressure of the heat transfer gas is calculated from the detected value. A substrate removal control method for a vacuum processing apparatus, characterized in that the pressure is adjusted to a value .

After performing surface treatment on the substrate to be processed while supplying a heat transfer gas for substrate temperature control between the substrate to be processed held on the substrate holding table in the vacuum vessel and the substrate holding table, The electrostatic attraction force between the substrate to be processed and the substrate holder due to the charge generated on the substrate to be processed in accordance with the surface treatment is detected based on the pushing load when the substrate to be processed is pushed up, and the detection When the value is equal to or greater than a predetermined value, the pushing operation is stopped before the pushing force reaches the shear stress limit of the substrate to be processed, and the heat transfer gas is supplied again between the substrate to be processed and the substrate holder. Then, the substrate removal control of the vacuum processing apparatus that peels off the substrate to be processed from the substrate holder by feedback-controlling the push-up force and the pressure of the heat transfer gas based on the detection value A law,
Supply of heat transfer gas when the detection value detected based on the thrust load when the substrate to be processed is thrust exceeds the initial set value corresponding to the external force applied to the thrust mechanism without electrostatic adsorption The substrate removal control method for a vacuum processing apparatus is characterized in that the pressure of the heat transfer gas is adjusted to a pressure difference between the detected value and the initial set value.