JP3784274B2

JP3784274B2 - Electrostatic chuck

Info

Publication number: JP3784274B2
Application number: JP2001132725A
Authority: JP
Inventors: 和一口町
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2001-04-27
Filing date: 2001-04-27
Publication date: 2006-06-07
Anticipated expiration: 2021-04-27
Also published as: JP2002329776A

Description

【０００１】
【発明の属する技術分野】
本発明は、ＰＶＤ装置、ＣＶＤ装置、イオンプレーティング装置、蒸着装置等の成膜装置やエッチング装置において、例えば半導体ウエハ等の被加工物を保持するのに用いる静電チャックに関するものである。
【０００２】
【従来の技術】
従来、ＰＶＤ装置、ＣＶＤ装置、イオンプレーティング装置、蒸着装置等の成膜装置やエッチング装置では、被加工物を精度良く固定するため、平坦かつ平滑に仕上げられた板状体の表面に強制的に吸着させることが行われており、この吸着手段として、静電吸着力を利用した静電チャックが用いられている。
【０００３】
これら成膜装置やエッチング装置に用いられる従来の静電チャックは、板状セラミック体の内部やその一方の主面（一方の最も広い面）に静電吸着用電極を備えるとともに、上記板状セラミック体の他方の主面（他方の最も広い面）を吸着面としたもので、静電吸着用電極に電圧を印加して被加工物との間に誘電分極によるクーロン力や微少な漏れ電流によるジョンソン・ラーベック力等の静電吸着力を発現させることにより、被加工物を吸着面に強制的に吸着固定させることができるようになっており、この時、被加工物の保持精度は、吸着面の面精度に倣うことから、吸着面全体を平滑かつ平坦に仕上げたものが用いられていた。
【０００４】
【発明が解決しようとする課題】
ところで、これら成膜装置やエッチング装置では、その多くが真空中での処理のため、被加工物の温度を如何に均一に保つか、また各種処理時に発生する熱を如何に外部へ逃がすかが重要な要件となっており、また、被加工物の処理時間を短くするためには、成膜やエッチングに要する本来の時間以外の時間、即ち被加工物を吸着面に載せてから静電吸着力により吸着保持するまでの時間及び吸着面から被加工物を離脱させるまでの時間を短縮する必要があり、特に被加工物の離脱時間の短縮が重要な要件となっている。
【０００５】
しかしながら、従来の静電チャックの吸着面は、前述したように平滑かつ平坦に仕上げられているため、静電吸着用電極への通電を止めても直ちに被加工物を離脱させることができないといった課題があった。
【０００６】
即ち、静電チャックによる吸着原理は、板状セラミック体の吸着面近傍と、被加工物の当接面近傍にそれぞれ極性の異なる電荷を帯電させることにより静電吸着力を発現させ、被加工物を吸着面に吸着させるのであるが、被加工物を離脱させるため、静電吸着用電極への通電を止めても板状セラミック体の吸着面近傍の電荷が直ちになくならず、残留吸着力として残るため、被加工物を吸着面より直ちに離脱させることができなかった。
【０００７】
また、吸着面を平滑かつ平坦に仕上げたとしても、ミクロ的に見ると、静電チャックの吸着面と被加工物との間には、吸着面の表面粗さや加工傷等の凹凸、あるいは被加工物の反り等により実際に接触している面積が小さく、さらに真空中では大気中にくらべて熱伝導量が小さいこと、被加工物の中央部は周縁部に比較して熱引けが悪いこと等の理由によって、成膜時やエッチング時に被加工物に発生した熱を均一に逃がすことができず、被加工物の温度分布を一様にすることができないため、成膜時の膜厚みが不均一となったり、エッチング時の形状に悪影響を与えるといった課題があった。
【０００８】
そこで、図５に示すように、吸着面２３に様々なパターン形状を有する深さ数十〜数百μｍ程度のガス溝２４を形成するとともに、上記ガス溝２４に、Ｈｅガス等の熱伝導性ガスを供給するためのガス導入孔２５を備えた静電チャック２１が提案されている（特許２６２６６１８号公報、特開平９−１３４９５１号公報、特開平９−２３２４１５号公報、特開平７−８６３８５号公報等参照）。
【０００９】
このような静電チャック２１によれば、吸着面２３にガス溝２４を設け、被加工物との接触面積を少なくすることができるため、静電吸着用電極２６への通電を止めた時、板状セラミック体２２の吸着面近傍に存在する電荷が少なく残留吸着力を小さくできるため、被加工物の離脱性を高めることができるといった利点があった。
【００１０】
しかしながら、このような静電チャック２１では、吸着面２３にガス溝２４を設けたことにより、吸着面２３と直接接触している部分の被加工物表面の温度と、ガス溝２４と接している部分の被加工物表面の温度との間には温度差が発生し、この温度差を小さくするため、被加工物とガス溝２４とで構成される空間にガス導入孔２５よりＨｅ等の熱伝導性ガスを供給することで、ガス溝２４と被加工物との間の熱伝達特性を高め、吸着面２３と被加工物との間の熱伝達効率に近づけることにより、被加工物の温度分布が一様となるように制御することが行われているが、このように被加工物とガス溝２４とで構成される空間にＨｅ等の熱伝導性ガスを供給したとしても、吸着面２３の占める割合が多く、吸着面２３とガス溝２４とが交互に配置された構造となっていること、被加工物の中央部は周縁部に比較して熱引けが悪いこと等から十分に満足できるものではなく、被加工物のさらなる温度均一性が要求されていた。
【００１１】
また、吸着面２３に様々なパターン形状を有するガス溝２４を形成したものでは、ガス溝２４によって区画される領域の吸着面２３の周縁にはシャープエッジが形成されており、被加工物がシリコンウエハのように比較的硬度の低いものである場合、その吸着時や離脱時の摺動によって傷付けられたり、エッジが欠けたりしてパーティクルが発生し、このパーティクルが被加工物に付着すると、成膜精度やエッチング精度に悪影響を与える恐れもあった。
【００１２】
【課題を解決するための手段】
そこで、上記課題に鑑み、請求項１に係る発明は、板状セラミック体の一方の主面又は内部に静電吸着用電極を備えるとともに、上記板状セラミック体の他方の主面にガス溝を備え、上記ガス溝で囲まれる領域を吸着面とした静電チャックにおいて、上記板状セラミック体を切断した時の吸着面の形状を、柱状で中央に平坦部を有する略円弧状凸部とし、該略円弧状凸部とガス溝側面との交点から略円弧状凸部の平坦部までの高さを０．５〜１０μｍであり前記交点から前記平坦部までの円弧状部の幅よりも小さいものとしたことを特徴とする。
【００１３】
また、請求項２に係る発明は、板状セラミック体の一方の主面又は内部に静電吸着用電極を備えるとともに、上記板状セラミック体の他方の主面にガス溝を備え、上記ガス溝で囲まれる領域を吸着面とした静電チャックにおいて、上記板状セラミック体を切断した時の吸着面の形状を、２つの円弧状凸部と、該２つの円弧状凸部の略中央部内方に凹むように設けられた円弧状凹部とから構成し、上記略円弧状凸部とガス溝側面との交点から略円弧状凸部の頂部までの高さを０．５〜１０μｍとしたことを特徴とする。
【００１４】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【００１５】
図１は本発明に係る静電チャックを示す図で、（ａ）はその正面図、（ｂ）はその断面図である。
【００１６】
この静電チャック１は、シリコンウエハ等の被加工物と同程度の大きさを有する円盤状をした板状セラミック体２中に、一対の静電吸着用電極３を埋設するとともに、上記板状セラミック体２の他方の主面（他方の最も広い面）には、ガス溝５を設け、ガス溝５で囲まれる領域の凸部頂面を吸着面６としてある。その為、被加工物を吸着面６に載せ、静電吸着用電極３間に通電して静電吸着用電極３と被加工物との間に静電吸着力を発現させることにより、吸着面６に被加工物を吸着固定するようになっている。なお、４は板状セラミック体２の一方の主面側に接合され、静電吸着用電極３と電気的に接続された給電端子である。
【００１７】
また、板状セラミック体２の中央部には、一方の主面からガス溝底面まで連通するガス導入孔７を有し、上記吸着面６に被加工物を吸着した時、被加工物とガス溝５とで構成される空間にＨｅガス等の熱伝導性ガスを供給することにより、ガス溝５と被加工物との間の熱伝達特性を高め、吸着面６と被加工物との間の熱伝達効率に近づけることにより、被加工物の温度分布が一様となるように制御するようになっている。
【００１８】
なお、この静電チャック１では、板状セラミック体２の他方の主面周縁部は閉じられた円環状の凸部としてあり、被加工物とガス溝５とで構成される空間に供給された熱伝導性ガスが外部に多量に漏れることを防止するようにしてある。
【００１９】
また、図１（ｂ）のＡ部を拡大した断面図を図２に示すように、板状セラミック体２を切断した時の吸着面６の形状は、中央に平坦部１０を有する略円弧状凸部８としてあり、この略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）を０．５〜１０μｍとしてある。
【００２０】
その為、本発明によれば、被加工物の吸着時及び離脱時に、被加工物が吸着面６と摺動したとしても、略円弧状凸部８とガス溝側面９とで構成されるエッジ部（交点Ｓ）が、略円弧状凸部８の平坦部１０より低い位置にあるため、吸着面６のエッジ部で被加工物を引っ掻いたり、エッジ部が欠けるようなことがないため、パーティクルの発生を効果的に防止することができる。
【００２１】
特に、吸着面６が幅広で、かつ吸着面全体が平坦面であると、被加工物が吸着面６に吸着された時、その間には隙間が殆どなく、ガス溝５に充填された熱伝導性ガスが被加工物と吸着面６との間に流れ難くなり、その結果、吸着面中央部上に位置する被加工物の表面温度が、吸着面周縁部上に位置する被加工物の表面温度より小さくなり、被加工物の全体では表面温度にバラツキが発生するのであるが、本発明によれば、略円弧状凸部８とガス溝側面９との交点Ｓが、略円弧状凸部８の平坦部１０より低く位置にあることから、被加工物と吸着面６との隙間にも熱伝導性ガスが流れ易くなり、特に被加工物と吸着面中央との隙間にも熱伝導性ガスを供給することができるため、被加工物の全体の表面温度を一様にすることができる。
【００２２】
さらに、被加工物を吸着面６に吸着すると、吸着面６の表面形状に倣って固定されるのであるが、静電吸着用電極３への通電を止めると、若干変形していた被加工物には元の状態に戻ろうとする力が働くため、被加工物の離脱性を高めることができる。
【００２３】
ただし、略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）が０．５μｍ未満であると、吸着時や離脱時に吸着面６のエッジ部が被加工物と当接し、被加工物を引っ掻いて傷を付けたり、エッジ部に欠けが発生する恐れがあるとともに、被加工物と吸着面６との隙間に熱伝導性ガスを送り込む効果が小さくなり、さらには離脱時において、被加工物が吸着面６から離れようとする力が小さいため、離脱時間を短くすることが難しい。
【００２４】
一方、略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）が１０μｍを超えると、被加工物と吸着面６との接触面積が少なくなり、吸着力が低下する。
【００２５】
その為、略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）は０．５〜１０μｍとすることが良い。
【００２６】
また、吸着面６に形成する円弧状部１１は、ガス溝側面９より０．１〜３ｍｍ、好ましくは０．１〜１ｍｍの幅Ｋで形成することが好ましい。
【００２７】
なぜなら、円弧状部１１の幅Ｋがガス溝側面９より０．１ｍｍ未満であると、被加工物と吸着面６との隙間に熱伝導性ガスを送り込む効果が小さくなり、また離脱時において、被加工物が吸着面６から離れようとする力が小さいため、離脱時間を短くすることができないからであり、逆に円弧状部１１の幅Ｋがガス溝側面９より１０ｍｍを超えると、被加工物との接触面積が小さくなり過ぎ、吸着力が大きく低下するといった不都合があるからである。
【００２８】
さらに、パーティクルの発生を防止するためには、吸着面６の面粗さは算術平均粗さ（Ｒａ）で０．２μｍ以下、好ましくは０．１μｍ以下、更に好ましくは０．０５μｍ以下とするが良い。
【００２９】
ところで、このような静電チャック１を製造する方法としては、セラミックグリーンシートの積層技術を用いるか、プレス成形技術を用いて板状セラミック体２を製作する。
【００３０】
例えば、セラミックグリーンシートの積層技術を用いて板状セラミック体２を製作する場合、複数枚のセラミックグリーンシートを用意し、あるセラミックグリーンシート上に静電吸着用電極３をなす導体ペーストを印刷するか、あるいは金属箔又は金網を載せ、残りのセラミックグリーンシートを積み重ねて積層し、セラミックグリーンシートを焼結させることができる温度にて焼成することにより得ることができる。
【００３１】
また、プレス成形技術を用いて板状セラミック体２を製作する場合、セラミック原料粉末を金型中に充填してプレス成形した後、成形体上に静電吸着用電極３をなす導体ペーストを印刷するか、あるいは金属箔又は金網を載せ、さらにセラミック原料粉末を充填した後、ホットプレスで焼成することにより得ることができる。
【００３２】
次いで、得られた板状セラミック体２の一方の主面に給電端子４を挿入、固定するための穴を穿孔し、この穴に給電端子４を挿入してロウ付け等の接合技術を持ちいて接合する。
【００３３】
次に、板状セラミック体２の他方の主面に、ガス溝５を形成するのであるが、ガス溝５の形成にあたっては、ブラスト加工やマシニング加工、あるいは超音波加工等を用い、深さが数十μｍから数百μｍのガス溝を所定のパターン形状に形成する。
【００３４】
しかる後、ガス溝５で囲まれる領域の凸部頂面が平坦でかつ同一平面上に位置するようにするため、ラッピング加工を施す。この時、ラップ板として鋳鉄製のものを用い、１０μｍから３μｍの大きさを有するダイヤモンド砥粒を用いてラッピングする。なお、さらに銅盤や錫盤を用いて仕上げ研磨を施しても構わない。
【００３５】
そして、本発明では、さらに図４に示すように、ポリウレタン等の樹脂パッド５２を貼り付けたラップ板５１を用い、回転するラップ板５１の周縁部に板状セラミック体２の他方の主面を押し当てながら自転させた状態で、板状セラミック体２とラップ板５１との間にコロイダルシリカを供給しながらラップ加工を行うことにより、板状セラミック体２を切断した時の吸着面６の形状を、中央に平坦部１０を有する略円弧状凸部８とし、この略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）を０．５〜１０μｍとする。なお、吸着面６の形状を上述した形状とするには、ラップ板５１に貼りつける樹脂パッド５２の厚みが重要で、その厚みを１〜３ｍｍとすることが好ましい。
【００３６】
次に、本発明の他の実施形態について説明する。
【００３７】
図３は図１（ｂ）のＡ部の他の形態を示す断面図で、板状セラミック体２を切断した時の吸着面６の形状は、２つの円弧状凸部１５と、これら２つの円弧状凸部１５の略中央部内方に凹むように設けられた円弧状凹部１６とからなり、略円弧状凸部１５とガス溝側面９との交点Ｓから略円弧状凸部１５の頂部１７までの高さ（Ｈ２）を０．５〜１０μｍとしてある。
【００３８】
その為、図３に示すような吸着面６を有する静電チャック１によれば、被加工物の吸着時及び離脱時に、被加工物が吸着面６と摺動したとしても、略円弧状凸部１５とガス溝側面９とで構成されるエッジ部（交点Ｓ）が、略円弧状凸部１５の頂部１７より低い位置にあるため、吸着面６のエッジ部で被加工物を引っ掻いたり、エッジ部が欠けるようなことがないため、パーティクルの発生を効果的に防止することができる。
【００３９】
また、本発明によれば、略円弧状凸部１５とガス溝側面９との交点Ｓが、略円弧状凸部１５の頂部１７より低くい位置にあることから、被加工物と吸着面６との隙間にも熱伝導性ガスが流れ易くなり、特に２つの円弧状凸部１５の略中央部内方に円弧状凹部１６を設けたことから、被加工物と吸着面中央との隙間にも十分な量の熱伝導性ガスを流すことができるため、被加工物の全体の表面温度を一様にすることができる。
【００４０】
さらに、被加工物を吸着面６に吸着すると、吸着面６の表面形状に倣って固定されるのであるが、静電吸着用電極３への通電を止めると、若干変形していた被加工物には元の状態に戻ろうとする力が働くのであるが、特に２つの円弧状凸部１５の略中央部内方に円弧状凹部１６を設けたことから、静電吸着用電極３への通電を止めた時に被加工物に発生する元の状態に戻ろうとする力を大きくすることができるため、被加工物の離脱性をさらに高めることができる。
【００４１】
そして、このように効果を奏するためには、上述したのと同様の理由により、略円弧状凸部１５とガス溝側面９との交点Ｓから略円弧状凸部１５の頂部１７までの高さ（Ｈ２）を０．５〜１０μｍとすることが良く、さらに吸着面６に形成する円弧状部１８は、ガス溝側面９より０．１〜３ｍｍ、好ましくは０．１〜１ｍｍの幅Ｋで形成し、吸着面６の面粗さは算術平均粗さ（Ｒａ）で０．２μｍ以下、好ましくは０．１μｍ以下、更に好ましくは０．０５μｍ以下とするが良い。
【００４２】
なお、板状セラミック体２を切断した時の吸着面６の形状を図３に示すような形状とするには、ポリウレタン等の樹脂パッドを貼り付けたラップ板を用い、砥粒としてコロイダルシリカを用いたラッピング加工の加工時間を０．５時間〜１０時間程度とすることにより達成することができる。
【００４３】
【実施例】
ここで、図２に示すような形状を有する吸着面６を備えた本発明の静電チャック１と、図５に示すような吸着面全体が平坦面である従来の静電チャック２１を用意し、シリコンウエハを吸着固定した後にシリコンウエハに付着するパーティクル数を測定する実験を行った。
【００４４】
本実験にあたっては、本発明の静電チャック１及び従来の静電チャック２１とも大きさ、材質等は全て同一とし、吸着面６，２３に形状のみ異ならせるようにした。
【００４５】
具体的には、以下の通りである。
【００４６】

また、吸着面６が図２に示す形状を有するものにおいては、略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）を変化させるようにした。
【００４７】
そして、実験にあたっては、製作した静電チャック１，２１の吸着面６，２３に８インチのシリコンウエハを載せた状態で静電吸着用電極３，２６に通電して静電吸着力を発現させ、シリコンウエハを吸着面６，２３に固定した後、ガス導入孔７，２５よりＨｅガスを供給し、シリコンウエハに７００Ｐａの背圧をかけた状態で静電チャックを２００℃まで加熱し、この時のシリコンウエハ表面における温度分布をサーモビュアにより測定した後、冷却して室温に戻し、静電吸着用電極３，２６への通電を止めてシリコンウエハを離脱させた時のシリコンウエハに付着する粒径０．１５μｍ以上のパーティクル数をパーティクルカウンターにて測定した。
【００４８】
また、静電吸着用電極３，２６への通電を止めてから、シリコンウエハの背圧が１０Ｐａとなるまでの時間を離脱時間として測定した。
【００４９】
結果はそれぞれ表１に示す通りである。
【００５０】
なお、シリコンウエハの温度分布の評価にあたっては、サーモビュアにより測定した。
【００５１】
【表１】

【００５２】
この結果、表１より判るように、試料Ｎｏ．１の従来の静電チャック２１のように、吸着面全体が平坦面からなるものでは、シリコンウエハに付着しているパーティクル数が９７３８個と多かった。そこで、パーティクルの付着位置を確認して見ると、吸着面２３のエッジ部と当接した位置にパーティクルの付着が目立っており、この現象から吸着面２３のエッジ部によりシリコンウエハが傷付けられたり、エッジ部に欠けや脱粒が発生し、パーティクルが付着したものと思われる。
【００５３】
また、シリコンウエハと吸着面２３との隙間にＨｅガスが流れ難いため、シリコンウエハの温度バラツキが１０．７℃と大きく、さらにはシリコンウエハの離脱時間も２５秒と長かった。
【００５４】
これに対し、吸着面６の形状を中央に平坦部１０を有する略円弧状凸部８としたものでは、シリコンウエハに付着しているパーティクル数を大幅に低減することができるとともに、シリコンウエハの離脱時間を短縮することができ、さらにはシリコンウエハ表面における温度バラツキも低減することができた。
【００５５】
この中でも試料Ｎｏ．３〜１０に示すように、略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）を０．５〜１０μｍとしたものは、シリコンウエハに付着しているパーティクル数を２０００個以下にまで低減できるとともに、シリコンウエハの離脱時間を１５秒以内に抑えることができ、さらにはシリコンウエハ表面における温度バラツキを５℃以内とすることができ優れていた。
【００５６】
この結果より、吸着面６の形状を中央に平坦部１０を有する略円弧状凸部８とするとともに、略円弧状凸部８とガス溝側面９との交点Ｓから略円弧状凸部８の平坦部１０までの高さ（Ｈ１）を０．５〜１０μｍとすれば良いことが判る。
【００５７】
【発明の効果】
以上のように、本発明によれば、板状セラミック体の一方の主面又は内部に静電吸着用電極を備えるとともに、上記板状セラミック体の他方の主面にガス溝を備え、上記ガス溝で囲まれる領域を吸着面とした静電チャックにおいて、板状セラミック体を切断した時の吸着面の形状を、柱状で中央に平坦部を有する略円弧状凸部とし、該略円弧状凸部の始点から略円弧状凸部の平坦部までの高さを０．５〜１０μｍであり前記交点から前記平坦部までの円弧状部の幅よりも小さいものとするか、あるいは板状セラミック体を切断した時の吸着面の形状を、２つの円弧状凸部と、該２つの円弧状凸部の略中央部内方に凹むように設けられた円弧状凹部とから構成し、上記略円弧状凸部の始点から略円弧状凸部の頂部までの高さを０．５〜１０μｍとしたことによって、被加工物の温度分布が均一になるように吸着保持することができるため、本発明の静電チャックを用いて成膜処理を施せば、均一な膜厚みを持った膜を被着することができ、また、エッチング処理を施せば、所定形状の加工を行うことができる。
【００５８】
また、本発明の静電チャックは、吸着時や離脱時に被加工物を引っ掻くシャープエッジが少ないため、被加工物を傷付けることがなく、パーティクルの発生を従来の静電チャックと比較してさらに低減することができるとともに、被加工物の離脱性にも優れることから、成膜やエッチングのトータル時間を短縮し、生産効率を向上させることができる。
【図面の簡単な説明】
【図１】本発明に係る静電チャックを示す図で、（ａ）はその正面図、（ｂ）はその断面図である。
【図２】図１のＡ部を拡大した断面図である。
【図３】図１のＡ部を拡大した他の実施形態を示す断面図である。
【図４】本発明の静電チャックにおける吸着面の形成方法を示す概略図である。
【図５】従来の静電チャックを示す図で、（ａ）はその正面図、（ｂ）はその断面図である。
【符号の説明】
１：静電チャック
２：板状セラミック体
３：静電吸着用電極
４：給電端子
５：ガス溝
６：吸着面
７：ガス導入孔
８：略円弧状凸部
９：ガス溝側面
１０：略円弧状凸部中央の平坦部
１１：円弧状部
１５：円弧状凸部
１６：円弧状凹部
１７：円弧状凸部中央の平坦部
１８：円弧状部
Ｓ：略円弧状凸部とガス溝側面との交点
Ｈ1：略円弧状凸部とガス溝側面との交点から略円弧状凸部の平坦部までの高さ
Ｈ2：略円弧状凸部とガス溝側面との交点から略円弧状凸部の平坦部までの高さ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic chuck used to hold a workpiece such as a semiconductor wafer in a film forming apparatus or an etching apparatus such as a PVD apparatus, a CVD apparatus, an ion plating apparatus, or a vapor deposition apparatus.
[0002]
[Prior art]
Conventionally, in a film forming apparatus such as a PVD apparatus, a CVD apparatus, an ion plating apparatus, a vapor deposition apparatus, and an etching apparatus, the surface of a plate-like body finished flat and smooth is forcibly fixed in order to fix a workpiece with high accuracy. The electrostatic chuck using an electrostatic attraction force is used as the adsorption means.
[0003]
Conventional electrostatic chucks used in these film forming apparatuses and etching apparatuses are equipped with an electrode for electrostatic adsorption on the inside of a plate-like ceramic body or one main surface (one widest surface), and the plate-like ceramic. The other main surface of the body (the other widest surface) is the attracting surface. By applying a voltage to the electrostatic attracting electrode, it is caused by Coulomb force due to dielectric polarization between the workpiece and minute leakage current. By expressing electrostatic adsorption force such as Johnson-Rahbek force, the workpiece can be forcibly fixed to the adsorption surface. At this time, the accuracy of holding the workpiece is In order to follow the surface accuracy of the surface, the entire suction surface was smooth and flat.
[0004]
[Problems to be solved by the invention]
By the way, most of these film forming apparatuses and etching apparatuses are processed in a vacuum, so how to keep the temperature of the workpiece uniform and how to release the heat generated during various processes to the outside. It is an important requirement, and in order to shorten the processing time of the workpiece, time other than the original time required for film formation and etching, that is, electrostatic adsorption after placing the workpiece on the adsorption surface It is necessary to shorten the time until the workpiece is attracted and held by the force and the time until the workpiece is detached from the attracting surface, and in particular, shortening the separation time of the workpiece is an important requirement.
[0005]
However, since the attracting surface of the conventional electrostatic chuck is smooth and flat as described above, the work piece cannot be immediately detached even when the energization to the electrostatic attracting electrode is stopped. was there.
[0006]
In other words, the principle of adsorption by the electrostatic chuck is that electrostatic adsorption force is expressed by charging charges of different polarities near the adsorption surface of the plate-like ceramic body and the contact surface of the workpiece. However, in order to release the workpiece, the electric charge in the vicinity of the adsorption surface of the plate-like ceramic body does not immediately disappear even when the electrostatic adsorption electrode is turned off. As a result, the workpiece could not be immediately detached from the suction surface.
[0007]
Even if the attracting surface is smooth and flat, from a microscopic viewpoint, the surface between the attracting surface of the electrostatic chuck and the work piece may be uneven, such as surface roughness of the attracting surface, processing scratches, or the like. The actual contact area is small due to warpage of the workpiece, and the heat conduction is lower in the vacuum than in the atmosphere, and the center of the workpiece has poor heat shrinkage compared to the peripheral edge. For this reason, the heat generated in the work piece during film formation or etching cannot be released uniformly, and the temperature distribution of the work piece cannot be made uniform. There were problems such as non-uniformity and adverse effects on the shape during etching.
[0008]
Therefore, as shown in FIG. 5, a gas groove 24 having a depth of several tens to several hundreds μm having various pattern shapes is formed on the adsorption surface 23, and thermal conductivity of He gas or the like is formed in the gas groove 24. Electrostatic chucks 21 having gas introduction holes 25 for supplying gas have been proposed (Japanese Patent No. 2626618, Japanese Patent Application Laid-Open No. 9-134951, Japanese Patent Application Laid-Open No. 9-232415, and Japanese Patent Application Laid-Open No. 7-86385). (See publications).
[0009]
According to such an electrostatic chuck 21, since the gas groove 24 is provided on the suction surface 23 and the contact area with the workpiece can be reduced, when energization of the electrostatic suction electrode 26 is stopped, Since there is little electric charge existing in the vicinity of the adsorption surface of the plate-like ceramic body 22 and the residual adsorption force can be reduced, there is an advantage that the detachability of the workpiece can be improved.
[0010]
However, in such an electrostatic chuck 21, the gas groove 24 is provided on the suction surface 23, so that the surface of the workpiece surface in direct contact with the suction surface 23 is in contact with the gas groove 24. A temperature difference is generated between the temperature of the part of the workpiece surface, and in order to reduce this temperature difference, heat such as He is introduced into the space formed by the workpiece and the gas groove 24 from the gas introduction hole 25. By supplying the conductive gas, the heat transfer characteristic between the gas groove 24 and the workpiece is enhanced, and the temperature of the workpiece is increased by approaching the heat transfer efficiency between the suction surface 23 and the workpiece. Although the distribution is controlled so as to be uniform, even if a heat conductive gas such as He is supplied to the space formed by the workpiece and the gas groove 24 in this way, the adsorption surface 23 occupies a large proportion, and the adsorption surface 23 and the gas groove 24 are alternately arranged. The center part of the work piece is not fully satisfactory due to poor heat sinking compared to the peripheral part, and further temperature uniformity of the work piece is required. .
[0011]
Further, in the case where the gas grooves 24 having various pattern shapes are formed on the suction surface 23, sharp edges are formed on the periphery of the suction surface 23 in a region defined by the gas grooves 24, and the workpiece is made of silicon. If the wafer has a relatively low hardness such as a wafer, it is damaged by sliding at the time of adsorption or separation, or the edge is chipped to generate particles, and if these particles adhere to the work piece, There is also a risk of adversely affecting film accuracy and etching accuracy.
[0012]
[Means for Solving the Problems]
Therefore, in view of the above problems, the invention according to claim 1 includes an electrode for electrostatic attraction on one main surface or inside of the plate-like ceramic body, and a gas groove on the other main surface of the plate-like ceramic body. In the electrostatic chuck having a suction surface in a region surrounded by the gas groove, the shape of the suction surface when the plate-like ceramic body is cut is a substantially arc-shaped convex portion having a columnar shape and a flat portion at the center, The height from the intersection of the substantially arc-shaped convex portion and the gas groove side surface to the flat portion of the substantially arc-shaped convex portion is 0.5 to 10 μm, and is smaller than the width of the arc-shaped portion from the intersection to the flat portion. and characterized in that a thing.
[0013]
The invention according to claim 2 includes an electrode for electrostatic adsorption on one main surface or inside of the plate-shaped ceramic body, and a gas groove on the other main surface of the plate-shaped ceramic body. In the electrostatic chuck using the region surrounded by the adsorption surface as the adsorption surface, the shape of the adsorption surface when the plate-shaped ceramic body is cut is divided into two arc-shaped convex portions and an inner portion of a substantially central portion of the two arc-shaped convex portions. And the height from the intersection of the substantially arc-shaped convex portion and the gas groove side surface to the top of the substantially arc-shaped convex portion is set to 0.5 to 10 μm. Features.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0015]
1A and 1B are views showing an electrostatic chuck according to the present invention, in which FIG. 1A is a front view thereof and FIG. 1B is a sectional view thereof.
[0016]
The electrostatic chuck 1 embeds a pair of electrostatic attraction electrodes 3 in a disk-shaped plate-like ceramic body 2 having the same size as a workpiece such as a silicon wafer, and the plate-like shape. The gas groove 5 is provided on the other main surface (the other widest surface) of the ceramic body 2, and the top surface of the convex portion in the region surrounded by the gas groove 5 is used as the adsorption surface 6. For this reason, the work surface is placed on the suction surface 6 and energized between the electrostatic suction electrodes 3 to develop an electrostatic suction force between the electrostatic suction electrode 3 and the work piece. The work piece is fixed to 6 by suction. Reference numeral 4 denotes a power supply terminal joined to one main surface of the plate-like ceramic body 2 and electrically connected to the electrostatic adsorption electrode 3.
[0017]
Further, the central portion of the plate-like ceramic body 2 has a gas introduction hole 7 that communicates from one main surface to the bottom surface of the gas groove. When the workpiece is adsorbed on the adsorption surface 6, the workpiece and gas By supplying a heat conductive gas such as He gas to the space formed by the groove 5, heat transfer characteristics between the gas groove 5 and the workpiece are improved, and the space between the suction surface 6 and the workpiece is increased. The temperature distribution of the workpiece is controlled to be uniform by approaching the heat transfer efficiency.
[0018]
In this electrostatic chuck 1, the peripheral portion of the other main surface of the plate-like ceramic body 2 is a closed annular convex portion, and is supplied to a space constituted by the workpiece and the gas groove 5. The heat conductive gas is prevented from leaking a large amount to the outside.
[0019]
Further, as shown in FIG. 2 which is an enlarged cross-sectional view of part A of FIG. 1B, the shape of the suction surface 6 when the plate-like ceramic body 2 is cut is substantially arcuate with a flat part 10 at the center. The height 8 (H1) from the intersection S of the substantially arc-shaped convex portion 8 and the gas groove side surface 9 to the flat portion 10 of the substantially arc-shaped convex portion 8 is set to 0.5 to 10 μm.
[0020]
Therefore, according to the present invention, even when the workpiece slides on the suction surface 6 when the workpiece is sucked and detached, the edge constituted by the substantially arcuate convex portion 8 and the gas groove side surface 9 is formed. Since the portion (intersection point S) is located at a position lower than the flat portion 10 of the substantially arcuate convex portion 8, the workpiece is not scratched at the edge portion of the suction surface 6 or the edge portion is not chipped. Can be effectively prevented.
[0021]
In particular, if the adsorption surface 6 is wide and the entire adsorption surface is flat, when the workpiece is adsorbed on the adsorption surface 6, there is almost no gap between them, and the heat conduction filled in the gas groove 5. As a result, the surface temperature of the workpiece located on the central portion of the suction surface is reduced by the surface temperature of the workpiece located on the peripheral portion of the suction surface. According to the present invention, the intersection S between the substantially arc-shaped convex portion 8 and the gas groove side surface 9 is substantially arc-shaped convex portion. 8 is located lower than the flat portion 10 of FIG. 8, so that the heat conductive gas easily flows through the gap between the workpiece and the suction surface 6, and in particular, the thermal conductivity also in the gap between the workpiece and the suction surface center. Since gas can be supplied, the entire surface temperature of the workpiece can be made uniform.
[0022]
Further, when the workpiece is attracted to the attracting surface 6, the workpiece is fixed following the surface shape of the attracting surface 6, but when the energization to the electrostatic attracting electrode 3 is stopped, the workpiece that has been slightly deformed. Since a force is exerted to return to the original state, the detachability of the workpiece can be improved.
[0023]
However, if the height (H1) from the intersection S between the substantially arcuate convex portion 8 and the gas groove side surface 9 to the flat portion 10 of the substantially arcuate convex portion 8 is less than 0.5 μm, it is adsorbed during adsorption or separation. The edge portion of the surface 6 comes into contact with the workpiece, and the workpiece may be scratched and scratched, or the edge portion may be chipped, and the thermal conductivity in the gap between the workpiece and the adsorption surface 6 It is difficult to shorten the separation time because the effect of feeding the gas is reduced and the force to move the workpiece away from the suction surface 6 is small at the time of separation.
[0024]
On the other hand, if the height (H1) from the intersection S of the substantially arcuate convex portion 8 and the gas groove side surface 9 to the flat portion 10 of the substantially arcuate convex portion 8 exceeds 10 μm, the workpiece and the suction surface 6 The contact area is reduced and the adsorption power is reduced.
[0025]
Therefore, the height (H1) from the intersection S between the substantially arcuate convex portion 8 and the gas groove side surface 9 to the flat portion 10 of the substantially arcuate convex portion 8 is preferably 0.5 to 10 μm.
[0026]
Further, the arc-shaped portion 11 formed on the suction surface 6 is preferably formed with a width K of 0.1 to 3 mm, preferably 0.1 to 1 mm, from the gas groove side surface 9.
[0027]
This is because if the width K of the arcuate portion 11 is less than 0.1 mm from the gas groove side surface 9, the effect of sending the heat conductive gas into the gap between the workpiece and the suction surface 6 is reduced, and at the time of separation, This is because the separation force cannot be shortened because the force with which the work piece separates from the adsorption surface 6 is small, and conversely, if the width K of the arcuate portion 11 exceeds 10 mm from the gas groove side surface 9, This is because the contact area with the workpiece becomes too small, and the attractive force is greatly reduced.
[0028]
Furthermore, in order to prevent the generation of particles, the surface roughness of the suction surface 6 is 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.05 μm or less in terms of arithmetic average roughness (Ra). good.
[0029]
By the way, as a method of manufacturing such an electrostatic chuck 1, the plate-shaped ceramic body 2 is manufactured by using a ceramic green sheet laminating technique or a press forming technique.
[0030]
For example, when the plate-shaped ceramic body 2 is manufactured using the ceramic green sheet lamination technique, a plurality of ceramic green sheets are prepared, and a conductive paste forming the electrostatic adsorption electrode 3 is printed on a certain ceramic green sheet. Alternatively, it can be obtained by placing a metal foil or a wire mesh, stacking and laminating the remaining ceramic green sheets, and firing at a temperature at which the ceramic green sheets can be sintered.
[0031]
Further, when the plate-shaped ceramic body 2 is manufactured by using the press molding technique, the ceramic raw material powder is filled in a mold and press-molded, and then a conductive paste that forms the electrostatic adsorption electrode 3 is printed on the molded body. Alternatively, it can be obtained by placing a metal foil or a wire mesh, and further filling with ceramic raw material powder, followed by firing in a hot press.
[0032]
Next, a hole for inserting and fixing the power supply terminal 4 is drilled in one main surface of the obtained plate-shaped ceramic body 2, and the power supply terminal 4 is inserted into this hole to have a joining technique such as brazing. Join.
[0033]
Next, the gas groove 5 is formed on the other main surface of the plate-like ceramic body 2. The gas groove 5 is formed by using blasting, machining, ultrasonic processing, or the like. Gas grooves of several tens to several hundreds of μm are formed in a predetermined pattern shape.
[0034]
Thereafter, lapping is performed so that the top surface of the convex portion in the region surrounded by the gas groove 5 is flat and located on the same plane. At this time, a lapping plate made of cast iron is used, and lapping is performed using diamond abrasive grains having a size of 10 μm to 3 μm. Further, finish polishing may be performed using a copper disk or a tin disk.
[0035]
And in this invention, as shown in FIG. 4, the other main surface of the plate-shaped ceramic body 2 is used for the peripheral part of the rotating wrap board 51 using the wrap board 51 which affixed the resin pads 52, such as a polyurethane. The shape of the suction surface 6 when the plate-like ceramic body 2 is cut by performing lapping while supplying colloidal silica between the plate-like ceramic body 2 and the lap plate 51 in a state of rotating while pressing. Is a substantially arcuate convex part 8 having a flat part 10 at the center, and the height (H1) from the intersection S between the substantially arcuate convex part 8 and the gas groove side surface 9 to the flat part 10 of the substantially arcuate convex part 8. ) To 0.5 to 10 μm. In addition, in order to make the shape of the suction surface 6 the above-described shape, the thickness of the resin pad 52 to be attached to the lap plate 51 is important, and the thickness is preferably set to 1 to 3 mm.
[0036]
Next, another embodiment of the present invention will be described.
[0037]
FIG. 3 is a cross-sectional view showing another form of the A part of FIG. 1B, and the shape of the suction surface 6 when the plate-like ceramic body 2 is cut includes two arc-shaped convex parts 15 and these two parts. The arcuate convex part 15 is formed of an arcuate concave part 16 provided so as to be recessed inward of the substantially central part of the arcuate convex part 15, and from the intersection S between the substantially arcuate convex part 15 and the gas groove side surface 9 The height (H2) is set to 0.5 to 10 μm.
[0038]
Therefore, according to the electrostatic chuck 1 having the attracting surface 6 as shown in FIG. 3, even when the workpiece slides on the attracting surface 6 when the workpiece is attracted or detached, the substantially circular convex Since the edge portion (intersection S) composed of the portion 15 and the gas groove side surface 9 is located at a position lower than the top portion 17 of the substantially arcuate convex portion 15, the workpiece is scratched at the edge portion of the suction surface 6, Since the edge portion is not lost, the generation of particles can be effectively prevented.
[0039]
Further, according to the present invention, since the intersection S between the substantially arcuate convex portion 15 and the gas groove side surface 9 is located at a position lower than the top 17 of the substantially arcuate convex portion 15, the workpiece and the suction surface 6 The heat conductive gas easily flows in the gap between the two and the arcuate recess 16 is provided in the substantially central part of the two arcuate protrusions 15. Since a sufficient amount of thermally conductive gas can be flowed, the entire surface temperature of the workpiece can be made uniform.
[0040]
Further, when the workpiece is attracted to the attracting surface 6, the workpiece is fixed following the surface shape of the attracting surface 6, but when the energization to the electrostatic attracting electrode 3 is stopped, the workpiece that has been slightly deformed. However, since the arc-shaped concave portion 16 is provided in the substantially central part of the two arc-shaped convex portions 15, energization of the electrostatic chucking electrode 3 is performed. Since the force for returning to the original state generated in the workpiece when stopped can be increased, the detachability of the workpiece can be further enhanced.
[0041]
In order to achieve the effect as described above, for the same reason as described above, the height from the intersection S between the substantially arc-shaped convex portion 15 and the gas groove side surface 9 to the top portion 17 of the substantially arc-shaped convex portion 15. (H2) is preferably 0.5 to 10 μm, and the arc-shaped portion 18 formed on the adsorption surface 6 has a width K of 0.1 to 3 mm, preferably 0.1 to 1 mm from the gas groove side surface 9. The surface roughness of the adsorption surface 6 formed is 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.05 μm or less in terms of arithmetic average roughness (Ra).
[0042]
In addition, in order to make the shape of the adsorption surface 6 when the plate-shaped ceramic body 2 is cut into a shape as shown in FIG. 3, a lap plate to which a resin pad such as polyurethane is attached is used, and colloidal silica is used as abrasive grains. This can be achieved by setting the processing time of the lapping used to about 0.5 hours to 10 hours.
[0043]
【Example】
Here, the electrostatic chuck 1 of the present invention having the suction surface 6 having the shape as shown in FIG. 2 and the conventional electrostatic chuck 21 having the entire suction surface as shown in FIG. 5 as a flat surface are prepared. An experiment was conducted to measure the number of particles adhering to the silicon wafer after the silicon wafer was adsorbed and fixed.
[0044]
In this experiment, the electrostatic chuck 1 of the present invention and the conventional electrostatic chuck 21 are all the same in size, material, etc., and only the shapes of the attracting

surfaces

6 and 23 are different.
[0045]
Specifically, it is as follows.
[0046]

In the case where the suction surface 6 has the shape shown in FIG. 2, the height (H1) from the intersection S between the substantially arcuate convex portion 8 and the gas groove side surface 9 to the flat portion 10 of the substantially arcuate convex portion 8. Was changed.
[0047]
In the experiment, the

electrostatic chucking electrodes

3 and 26 are energized with an 8-inch silicon wafer placed on the chucking surfaces 6 and 23 of the manufactured

electrostatic chucks

1 and 21 to develop the electrostatic chucking force. After fixing the silicon wafer to the suction surfaces 6 and 23, He gas is supplied from the gas introduction holes 7 and 25, and the electrostatic chuck is heated to 200 ° C. with a back pressure of 700 Pa applied to the silicon wafer. After the temperature distribution on the surface of the silicon wafer is measured by a thermoviewer, the particles are attached to the silicon wafer when cooled and returned to room temperature, and the energization of the

electrostatic chucking electrodes

3 and 26 is stopped and the silicon wafer is detached. The number of particles having a diameter of 0.15 μm or more was measured with a particle counter.
[0048]
Further, the time from when the energization to the

electrostatic chucking electrodes

3 and 26 was stopped until the back pressure of the silicon wafer reached 10 Pa was measured as the separation time.
[0049]
The results are as shown in Table 1, respectively.
[0050]
The temperature distribution of the silicon wafer was evaluated using a thermoviewer.
[0051]
[Table 1]

[0052]
As a result, as can be seen from Table 1, the sample No. As in the conventional electrostatic chuck 21 of FIG. 1, the number of particles adhering to the silicon wafer was as large as 9738 when the entire attracting surface was a flat surface. Therefore, when the particle adhesion position is confirmed, particle adhesion is conspicuous at the position in contact with the edge portion of the adsorption surface 23, and from this phenomenon, the silicon wafer is damaged by the edge portion of the adsorption surface 23, It seems that chipping and degranulation occurred in the edge part, and particles adhered.
[0053]
Further, since the He gas hardly flows through the gap between the silicon wafer and the adsorption surface 23, the temperature variation of the silicon wafer was as large as 10.7 ° C., and the detachment time of the silicon wafer was as long as 25 seconds.
[0054]
On the other hand, when the shape of the suction surface 6 is a substantially arc-shaped convex portion 8 having a flat portion 10 in the center, the number of particles adhering to the silicon wafer can be greatly reduced, The separation time can be shortened, and furthermore, temperature variations on the silicon wafer surface can be reduced.
[0055]
Among these, sample no. As shown in 3 to 10, the height (H1) from the intersection S between the substantially arcuate convex portion 8 and the gas groove side surface 9 to the flat portion 10 of the substantially arcuate convex portion 8 is 0.5 to 10 μm. Can reduce the number of particles adhering to the silicon wafer to 2000 or less, can reduce the silicon wafer detachment time to within 15 seconds, and keep the temperature variation on the silicon wafer surface within 5 ° C. Could be better.
[0056]
As a result, the shape of the suction surface 6 is a substantially arc-shaped convex portion 8 having a flat portion 10 at the center, and the substantially arc-shaped convex portion 8 is formed from the intersection S between the substantially arc-shaped convex portion 8 and the gas groove side surface 9. It can be seen that the height (H1) to the flat portion 10 may be 0.5 to 10 μm.
[0057]
【The invention's effect】
As described above, according to the present invention, an electrode for electrostatic attraction is provided on one main surface or inside of a plate-like ceramic body, and a gas groove is provided on the other main surface of the plate-like ceramic body. In an electrostatic chuck having a suction surface in a region surrounded by a groove, the shape of the suction surface when the plate-shaped ceramic body is cut is a substantially arc-shaped convex portion having a columnar shape and a flat portion at the center. The height from the starting point of the part to the flat part of the substantially arc-shaped convex part is 0.5 to 10 μm and is smaller than the width of the arc-shaped part from the intersection to the flat part , or a plate-like ceramic body The shape of the suction surface when cutting is made up of two arc-shaped convex portions and an arc-shaped concave portion provided so as to be recessed in the substantially central portion of the two arc-shaped convex portions, The height from the starting point of the convex portion to the top of the substantially arc-shaped convex portion is 0.5 to 10 μm. As a result, the temperature distribution of the workpiece can be attracted and held so that the film has a uniform film thickness when the film is formed using the electrostatic chuck of the present invention. In addition, if an etching process is performed, a predetermined shape can be processed.
[0058]
In addition, the electrostatic chuck of the present invention has fewer sharp edges that scratch the workpiece when attracted or detached, so that the workpiece is not damaged and particle generation is further reduced compared to conventional electrostatic chucks. In addition, since the workpiece can be easily detached, the total time for film formation and etching can be shortened and the production efficiency can be improved.
[Brief description of the drawings]
1A and 1B are views showing an electrostatic chuck according to the present invention, in which FIG. 1A is a front view thereof, and FIG.
FIG. 2 is an enlarged cross-sectional view of a portion A in FIG.
FIG. 3 is a cross-sectional view showing another embodiment in which the portion A of FIG. 1 is enlarged.
FIG. 4 is a schematic view showing a method of forming an attracting surface in the electrostatic chuck of the present invention.
5A and 5B are diagrams showing a conventional electrostatic chuck, in which FIG. 5A is a front view thereof, and FIG. 5B is a cross-sectional view thereof.
[Explanation of symbols]
1: Electrostatic chuck 2: Plate-like ceramic body 3: Electrostatic chucking electrode 4: Feeding terminal 5: Gas groove 6: Suction surface 7: Gas introduction hole 8: Substantially arc-shaped convex portion 9: Gas groove side surface 10: Substantially Flat part 11 at the center of the arc-shaped convex part 11: Arc-shaped part 15: Arc-shaped convex part 16: Arc-shaped concave part 17: Flat part 18 at the center of the arc-shaped convex part 18: Arc-shaped part S: Substantially arc-shaped convex part and gas groove side surface Intersection H1: Height from the intersection of the substantially arc-shaped convex portion and the gas groove side surface to the flat portion of the substantially arc-shaped convex portion H2: The substantially arc-shaped convex portion from the intersection of the substantially arc-shaped convex portion and the gas groove side surface Height to flat part

Claims

An electrostatic adsorption electrode is provided on one main surface or inside of the plate-shaped ceramic body, a gas groove is provided on the other main surface of the plate-shaped ceramic body, and a region surrounded by the gas groove is defined as an adsorption surface. In the electric chuck, the shape of the suction surface when the plate-shaped ceramic body is cut is a substantially arc-shaped convex portion having a columnar shape and a flat portion at the center, and from the intersection of the substantially arc-shaped convex portion and the gas groove side surface. an electrostatic chuck, wherein the height of the flat portion of the substantially arc-shaped convex portion is smaller than the width of the arcuate portion from 0.5~10μm der Ri said intersection to said flat portion.

An electrostatic chucking electrode is provided on one main surface or inside of the plate-like ceramic body, a gas groove is provided on the other main surface of the plate-like ceramic body, and a region surrounded by the gas groove is used as a suction surface. In the electric chuck, the shape of the suction surface when the plate-shaped ceramic body is cut is two arc-shaped convex portions, and an arc-shaped concave portion provided so as to be recessed substantially inward of the central portion of the two arc-shaped convex portions. An electrostatic chuck characterized in that the height from the intersection of the substantially arcuate convex part and the gas groove side surface to the top of the substantially arcuate convex part is 0.5 to 10 μm.