JP3886770B2

JP3886770B2 - Wafer holding device

Info

Publication number: JP3886770B2
Application number: JP2001330253A
Authority: JP
Inventors: 敦司笹川
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2001-10-29
Filing date: 2001-10-29
Publication date: 2007-02-28
Anticipated expiration: 2021-10-29
Also published as: JP2003133403A

Description

【０００１】
【発明の属する技術分野】
本発明は、セラミック製のウェハ保持部材と金属製の不活性ガス導入管とをロウ付けして接合して成るウェハ保持装置であって、半導体ウェハや液晶装置用のガラス基板等のウェハを保持し搬送するための静電チャックやサセプター等としてのウェハ保持装置に関する。
【０００２】
【従来の技術】
従来、半導体集積回路素子等の製造工程で半導体ウェハに成膜を行なうためのＣＶＤ（Chemical Vapor Deposition）装置や半導体ウェハに微細加工処理を施すためのドライエッチング装置において、ウェハ保持部材としてサセプターが用いられている。
【０００３】
ウェハ保持部材が金属製であると、金属元素が半導体ウェハを汚染することから、近年ウェハ保持部材としてアルミナ（Ａｌ₂Ｏ₃）や窒化アルミニウム（ＡｌＮ）等を主成分とするセラミック製のサセプターが用いられている。また、セラミック製の静電チャックを用いて半導体ウェハを吸着固定することも行われている。
【０００４】
例えば、半導体集積回路素子等の製造工程で半導体ウェハに成膜を行なうＣＶＤ装置や半導体ウェハに微細加工処理を施すドライエッチング装置においては、図６に示すように半導体ウェハ２１を載置し保持するためのサセプターや静電チャックと呼ばれる円盤状のセラミック製のウェハ保持部材１１が使用される。ウェハ保持部材１１は、上面に半導体ウェハ２１を載置する載置面１１ａを有し、また下面１１ｂに金属製の不活性ガス導入管（以下、導入管という）１２がロウ付けで接合されている。この導入管１２は、載置面１１ａにヘリウム（Ｈｅ）ガスなどを供給し、載置面１１ａと半導体ウェハ２１との間の熱伝導性を向上させて半導体ウェハ２１の熱分布を均一化するものである。また、導入管１２に光ファイバを用いた測温素子を挿入し、載置面１１ａの温度を測定することも行われている。
【０００５】
なお、ウェハ保持部材１１の下面１１ｂと導入管１２とを接合する際には、これらをロウ材１４によって接合している。セラミック製のウェハ保持部材１１の下面１１ｂに、予めモリブデン（Ｍｏ）−マンガン（Ｍｎ），タングステン（Ｗ）−マンガン（Ｍｎ），銅（Ｃｕ）−チタン（Ｔｉ），銀（Ａｇ）−銅（Ｃｕ）−チタン（Ｔｉ）等のメタライズ層とそのメタライズ層上に被着されたニッケル（Ｎｉ）メッキ層の２層構造を有する金属層１３を被着しておき、金属層１３にロウ材１４を介して導入管１２が接合される。
【０００６】
また、ウェハ保持部材１１は、上面の半導体ウェハ２１を載置する載置面１１ａを、下面１１ｂに接合した導入管１２と電気的に導通させることにより、載置面１１ａ上の半導体ウェハ２１の有無を金属製の導入管１２を介して電気的に確認することが行われている。載置面１１ａと導入管１２との間の導通は、ウェハ保持部材１１の貫通孔１１ｃの内面に金属層１３を延出させることによって可能となる。
【０００７】
また、ウェハ保持部材１１と導入管１２との接合部には、両部材の熱膨張差により接合時の応力が残留し、接合部が剥がれ易くなるという問題がある。この対策のために、導入管１２の上端に形成された鍔部１２ａの裏面１２ｂに、ウェハ保持部材１１をなすセラミックスと熱膨張係数の近い材料から成る応力緩和用のセラミックリング１５をロウ付け接合し、セラミック製保持部材１１とセラミックリング１５とで熱膨張係数の異なる金属製の導入管１２を挟み込むことにより、ロウ付けの際に生じる応力が緩和できる。その結果、応力により導入管１２がウェハ保持部材１１から剥がれることを防止できる。
【０００８】
また、導入管１２の下端面には、ウェハ保持部材１１との接合後に延長用の金属管１６が溶接され、外部からの不活性ガスの導入が容易にできるようにされている。
【０００９】
【発明が解決しようとする課題】
しかしながら、上記従来のウェハ保持装置において、導入管１２は、金属層１３のうち、ウェハ保持部材１１の貫通孔１１ｃの下面１１ｂ側開口の周囲にある金属層１３ａにロウ材１４を介して接合される。この際、図４のように、貫通孔１１ｃの下面１１ｂ側開口において、金属層１３の厚みａはその表面張力により薄くなる。従って、金属管１６の溶接時や運搬時等に導入管１２に外力が加わると、金属層１３の薄い箇所に応力が集中し、金属層１３に厚さ方向のクラックが発生し金属層１３が切れて導通不良が生じるという問題があった。
【００１０】
また、図５に示すように貫通孔１１ｃの下面１１ｂ側開口に平面的な面取り（Ｃ面）加工を施した場合にも、面取り部の金属層１３は厚みａが薄くなって応力の集中し易い形状となり、上記の問題が発生する場合があった。
【００１１】
従って、本発明は上記従来の問題点に鑑みて完成されたものであり、その目的は、ウェハ保持部材のウェハの載置面と導入管との間の電気的な導通構造を改善し、載置面上のウェハの有無を電気的に確認することが長期にわたって良好にかつ高い信頼性でもってできるようにすることである。
【００１２】
【課題を解決するための手段】
本発明のウェハ保持装置は、上面にウェハを載置する載置面を有するとともに上下面間を貫通する貫通孔が形成されているセラミック製のウェハ保持部材と、上端に鍔部が形成されているとともに該鍔部が前記貫通孔の前記下面側開口の周囲にロウ付けされて前記貫通孔に同軸状に接合されている金属製の不活性ガス導入管とを具備したウェハ保持装置において、前記貫通孔の前記下面側開口に円弧状曲面とされた面取り部が設けられており、前記載置面と前記不活性ガス導入管とを電気的に導通させる金属層が、前記貫通孔の内面から前記面取り部を介して前記下面側開口の周囲にかけて連続して設けられていることを特徴とする。
好ましくは、本発明のウェハ保持装置において、前記面取り部は、曲率半径が１ｍｍ以上でウェハ保持部材の厚み以下の円弧状曲面であることを特徴とする。
好ましくは、本発明のウェハ保持装置において、前記不活性ガス導入管が前記ウェハ保持部材にロウ付けされる前記鍔部の裏面に、セラミックリングがロウ付けされていることを特徴とする。
【００１３】
本発明は、上記の構成により、ウェハ保持部材のウェハの載置面と不活性ガス導入管の導通構造が改善され、載置面上のウェハの有無を電気的に確認することが長期にわたって良好にできるようになるという作用効果を有する。
【００１４】
【発明の実施の形態】
本発明のウェハ保持装置について以下に詳細に説明する。図１は本発明のウェハ保持装置について実施の形態の一例を示す断面図である。図１において、１１はウェハ保持部材、１１ａはウェハ保持部材１１の上面のウェハの載置面、１１ｂはウェハ保持部材１１の下面であり導入管が接合される側の面である。また、１１ｃはウェハ保持部材１１の上下面間を貫通するガス導入用の貫通孔、１２は導入管、１３は金属層、１３ａは導入管１２の鍔部１２ａに接合される金属層、１３ｂは貫通孔１１ｃ内面の金属層である。また、１４はロウ材、１５は応力緩和用のセラミックリングである。なお、本発明を示す図１〜図３において図６と同じ部分には同じ符号を付している。
【００１５】
本発明のウェハ保持装置は、上面にウェハを載置する載置面１１ａを有するとともに上下面間を貫通する貫通孔１１ｃが形成されているセラミック製のウェハ保持部材１１と、上端に鍔部１２ａが形成されているとともに鍔部１２ａが貫通孔１１ｃの下面１１ｂ側開口の周囲にロウ付けされて貫通孔１１ｃに同軸状に接合されている金属製の導入管１２と、導入管１２の上端部を囲むように鍔部１２ａの裏面にロウ付けされたセラミックリング１５とを具備した基本構成である。
【００１６】
そして、図１に示すように、ウェハ保持部材１１はセラミックスからなる円盤状であり、上面にＳｉ，ＧａＡｓ等の半導体ウェハや液晶用ガラス基板等のウェハを載置する平坦な載置面１１ａを有し、載置面１１ａと下面１１ｂとを連通する貫通孔１１ｃを有している。ウェハ保持部材１１の下面１１ｂで貫通孔１１ｃの下面１１ｂ側開口の周囲に、導入管１２の鍔部１２ａがロウ付け接合される。ウェハ保持部材１１と導入管１２との具体的な接合構造は、ウェハ保持部材１１の下面１１ｂにメタライズ層と金属メッキ層の２層構造を有する金属層１３ａを形成しておき、ロウ材１４により導入管１２上端の鍔部１２ａをロウ付けして成る構造である。
【００１７】
そして、ウェハ保持部材１１の載置面１１ａにウェハを載置し、導入管１２よりヘリウム（Ｈｅ）等の不活性ガスを導入すると、載置面１１ａに形成された多数の溝等に不活性ガスが溜り、ウェハと載置面１１ａとの間の熱伝達性が向上し、ウェハに大きな熱分布が発生するのを抑制することができる。
【００１８】
ウェハ保持部材１１と導入管１２との接合は平面同士の接合であり、広い範囲でのロウ材１４の充填が可能であり、ガスのリーク防止に対し大きな効果が得られる。
【００１９】
また、ウェハ保持部材１１にロウ付けされる導入管１２の鍔部１２ａ（接合部）の厚みｔは０．１〜１ｍｍがよく、鍔部１２ａの幅ｄは１ｍｍ以上であることが好ましい。ｔが１ｍｍを超えると、ロウ付け時に鍔部１２ａの変形が起こりにくくなり応力緩和が不十分になるため、ウェハ保持部材１１に生じる応力が大きくなってセラミック製のウェハ保持部材１１が破壊されやすくなる。ｔが０．１ｍｍ未満では、鍔部１２ａの強度が不足することとなる。また、ｄが１ｍｍ未満では、接合による気密性が不十分となり不活性ガスが漏れやすくなる。
【００２０】
導入管１２の材質は、セラミックスの熱膨張率と近い金属材料であることから、Ｆｅ−Ｎｉ−Ｃｏ合金，Ｍｏ，Ｐｔ，Ｔｉ，Ｎｂなどがよい。
【００２１】
ロウ材１４の材質は、高温（４００〜６００℃）中で溶融や液化を生じないものがよく、Ａｇ−Ｃｕ合金系，Ａｇ系，Ａｕ系等のロウ材がよい。
【００２２】
ウェハ保持部材１１の材質は、アルミナ（Ａｌ₂Ｏ₃），窒化アルミニウム（ＡｌＮ），ジルコニア（ＺｒＯ₂）、炭化珪素（ＳｉＣ）、窒化珪素（Ｓｉ₃Ｎ₄）のうちの一種以上を主成分とするセラミックスである。特に、耐プラズマ性の点から、９９重量％以上の高純度のアルミナを主成分とし、二酸化珪素（ＳｉＯ₂），酸化マグネシウム（ＭｇＯ），酸化カルシウム（ＣａＯ）等の焼結助剤を含有するアルミナセラミックス、窒化アルミニウムを主成分とし周期律表の第２ａ族元素酸化物や第３ａ族元素酸化物を０．５〜２０重量％の範囲で含有する窒化アルミニウム質セラミックス、９９重量％以上のＡｌＮを主成分とする高純度窒化アルミニウム質セラミックスのいずれかが好適である。これらは、金属材料と違い化学反応しにくいため、金属元素による半導体ウェハへの汚染を低減できるという利点がある。
【００２３】
さらに、導入管１２の鍔部１２ａの裏面１２ｂには応力緩和用のセラミックリング１５をロウ付け接合している。具体的には、ウェハ保持部材１１と導入管１２とのロウ付けと同様に、セラミックリング１５の上面に金属層１３を形成しておき、ロウ材１４により導入管１２の鍔部１２ａの裏面１２ｂにロウ付けする。
【００２４】
本発明において、貫通孔１１ｃは下面１１ｂ側開口に曲率半径１ｍｍ以上でウェハ保持部材１１の厚み以下である円弧状曲面とされた面取り部Ａ（図２）が設けられており、セラミックリング１５の内周面と面取り部Ａの下面１１ｂ側の始点Ｐ（図３）との径方向における距離が２ｍｍ以下である。
【００２５】
即ち、図２に示すように、貫通孔１１ｃの下面１１ｂ側開口が円弧状曲面となるように面取りされていることにより、金属層１３の厚みが貫通孔１１ｃの下面１１ｂ側開口で薄くなることはなく、全体的に均一とすることができる。その結果、金属管１６の溶接時や運搬時等に導入管１２に外力が加わった際に、金属層１３の薄い箇所に応力が集中することが解消され、金属層１３に厚さ方向のクラックが発生し金属層１３が切れて導通不良が生じるということがなくなる。
【００２６】
貫通孔１１ｃの下面１１ｂ側開口の面取り部Ａの曲率半径が１ｍｍ未満では、金属層１３を形成するための導体ペーストを塗布した際に、その表面張力によって面取り部の金属層１３の厚さが薄くなり、厚さのばらつきが発生し易くなる。また、面取り部Ａがウェハ保持部材１１の厚みを超える曲率半径である場合、貫通孔１１ｃの載置面１１ａ側開口において貫通孔１１ｃ内面と載置面１１ａとのなす角度が鋭角となり、貫通孔１１ｃの載置面１１ａ側開口部の強度が不足し欠け等が発生し易くなる。
【００２７】
また、メタライズ層と金属メッキ層の２層構造を有する金属層１３は、その厚みが５〜３０μｍであることが好ましい。５μｍより薄い場合、ロウ材１４の浸食により金属層１３の密着強度が低下するため、不活性ガスの漏れが発生し易くなる。３０μｍより厚いと、金属層１３とセラミックスとの熱膨張係数差により金属層１３に加わる応力が大きくなり、金属層１３に亀裂が生じ易くなる。この金属層１３は、Ｍｏ−Ｍｎ，Ｗ−Ｍｎ，Ｃｕ−Ｔｉ，Ａｇ−Ｃｕ−Ｔｉ等から成るメタライズ層とＮｉメッキ層の２層構造で形成されている。
【００２８】
また、図３は導入管１２の上端部のロウ付け部を拡大した拡大断面図であり、導入管１２の鍔部１２ａの裏面１２ｂには応力緩和用のセラミックリング１５がロウ付け接合されている。セラミックリング１５は、ウェハ保持部材１１を成すセラミックスと熱膨張係数が同じか近似したアルミナセラミックス，窒化アルミニウムセラミックス等のセラミック材料から成るのがよい。このセラミックリング１５は、ウェハ保持部材１１とで熱膨張の異なる導入管１２を挟み込むことにより、ロウ付けの際に生じる応力を緩和でき、導入管１２がウェハ保持部材１１から剥がれることを防止できる。特に、セラミックリング１５がウェハ保持部材１１と同じセラミックスであることが好適である。
【００２９】
本発明では、セラミックリング１５の内周面と貫通孔１１ｃの面取り部Ａの下面１１ｂ側の始点Ｐ（図３）との径方向における距離が２ｍｍ以下である。つまり、図３に示すように、セラミックリング１５の内径Ｒ１と、面取り部Ａの下面１１ｂ側のある始点Ｐおよびそれに対して貫通孔１１ｃの中心に対称な位置にある他の始点Ｐを結んだ直線で決まる直径Ｒ２との差が４ｍｍ以下、即ち一方の始点Ｐにおける差が２ｍｍ以下である。２ｍｍを超えると、ウェハ保持部材１１とセラミックリング１５とで導入管１２を挟み込むことによるロウ付け時の応力の緩和が不十分になる。
【００３０】
また、セラミックリング１５の外径と導入管１２の鍔部１２ａの外径との差が２ｍｍ以下であることが好ましい。セラミックリング１５の外径が導入管１２の鍔部１２ａの外径より２ｍｍを超えて小さくなると、セラミックリング１５で導入管１２を挟み込むことによるロウ付け時の応力の緩和が不十分になる。また、セラミックリング１５の外径が導入管１２の鍔部１２ａの外径より２ｍｍを超えて大きくなると、ウェハ保持部材１１の下面１１ｂとセラミックリング１５との間にロウ材が流出して塊、所謂ロウ材溜まりが形成され、ウェハ保持部材１１やセラミックリング１５が破損し易くなる。このようなロウ材溜まりの形成を効果的に防ぐには、セラミックリング１５の鍔部１２ａの外周端に面取り加工を施すことが好ましく、ロウ材の滑らかなメニスカスを形成させることができて応力が緩和される。
【００３１】
また、セラミックリング１５の厚みは１ｍｍ以上が良い。１ｍｍ未満では、ロウ付け時の応力緩和の効果が不十分となり、より好ましくは５ｍｍ以上が良い。上限については特に制約はないが実用的な構造上許容される範囲内とすれば良い。
【００３２】
なお、本発明のウェハ保持装置は、半導体の製造工程で半導体ウェハを保持する際に好適に使用することができるが、この他に液晶表示装置の製造工程における液晶用ガラス基板などの各種ウェハについても使用できる。
【００３３】
【発明の効果】
本発明は、上面にウェハを載置する載置面を有するとともに上下面間を貫通する貫通孔が形成されているセラミック製のウェハ保持部材と、上端に鍔部が形成されているとともに鍔部が貫通孔の下面側開口の周囲にロウ付けされて貫通孔に同軸状に接合されている金属製の導入管とを具備し、貫通孔の下面側開口に曲率半径が１ｍｍ以上でウェハ保持部材の厚み以下である円弧状曲面とされた面取り部が設けられており、載置面と不活性ガス導入管とを電気的に導通させる金属層が、貫通孔の内面から面取り部を介して下面側開口の周囲にかけて連続して設けられていることにより、ウェハ保持部材のウェハの載置面と導入管の導通構造が改善され、載置面上のウェハの有無を電気的に確認することが長期にわたって良好にできるようになるという作用効果を有する。
【００３４】
即ち、導入管の鍔部を貫通孔の下面側開口の周囲にロウ付けするための金属層形成用の導体ペーストが、その表面張力により貫通孔の下面側開口で厚みが薄くなることが解消されて金属層の厚みが均一となる。そのため、金属層の薄い箇所への応力集中をなくして金属層の切断による導通不良の発生を防止することができる。従って、ウェハ保持部材の載置面と導入管との間で良好な導通特性を実現でき、載置面上のウェハの有無を電気的に検出することが長期にわたって良好にかつ高い信頼性でもってできるようになる。
【図面の簡単な説明】
【図１】本発明のウェハ保持装置について実施の形態の例を示す断面図である。
【図２】図１のウェハ保持装置におけるウェハ保持部材の貫通孔の下面側開口部の拡大断面図である。
【図３】図１のウェハ保持装置における導入管のロウ付け部の拡大断面図である。
【図４】従来のウェハ保持装置におけるウェハ保持部材の貫通孔の下面側開口部の拡大断面図である。
【図５】従来の他のウェハ保持装置におけるウェハ保持部材の貫通孔の下面側開口部の拡大断面図である。
【図６】従来のウェハ保持装置の一例を示す断面図である。
【符号の説明】
１１：ウェハ保持部材
１１ａ：載置面
１１ｂ：下面
１１ｃ：貫通孔
１２：不活性ガス導入管
１２ａ：鍔部
１２ｂ：鍔部の裏面
１３，１３ａ，１３ｂ：金属層
１４：ロウ材
１５：セラミックリング
１６：金属管
２１：半導体ウェハ[0001]
BACKGROUND OF THE INVENTION
The present invention is a wafer holding device formed by brazing a ceramic wafer holding member and a metal inert gas introducing pipe and holding the wafer, such as a semiconductor wafer or a glass substrate for a liquid crystal device. The present invention relates to a wafer holding device as an electrostatic chuck, a susceptor, etc.
[0002]
[Prior art]
Conventionally, a susceptor is used as a wafer holding member in a CVD (Chemical Vapor Deposition) apparatus for forming a film on a semiconductor wafer in a manufacturing process of a semiconductor integrated circuit element or the like, or in a dry etching apparatus for performing fine processing on a semiconductor wafer. It has been.
[0003]
If the wafer holding member is made of metal, the metal element contaminates the semiconductor wafer. In recent years, a ceramic susceptor mainly composed of alumina (Al ₂ O ₃ ), aluminum nitride (AlN) or the like has been used as the wafer holding member. It is used. Also, a semiconductor wafer is attracted and fixed using a ceramic electrostatic chuck.
[0004]
For example, in a CVD apparatus for forming a film on a semiconductor wafer in a manufacturing process of a semiconductor integrated circuit element or the like and a dry etching apparatus for performing fine processing on a semiconductor wafer, the semiconductor wafer 21 is placed and held as shown in FIG. For this purpose, a disc-shaped ceramic wafer holding member 11 called a susceptor or electrostatic chuck is used. The wafer holding member 11 has a placement surface 11a on which the semiconductor wafer 21 is placed on the upper surface, and a metal inert gas introduction tube (hereinafter referred to as introduction tube) 12 is joined to the lower surface 11b by brazing. Yes. The introduction pipe 12 supplies helium (He) gas or the like to the mounting surface 11a, improves the thermal conductivity between the mounting surface 11a and the semiconductor wafer 21, and makes the heat distribution of the semiconductor wafer 21 uniform. Is. In addition, a temperature measuring element using an optical fiber is inserted into the introduction tube 12 to measure the temperature of the mounting surface 11a.
[0005]
When the lower surface 11 b of the wafer holding member 11 and the introduction pipe 12 are joined, they are joined by the brazing material 14. On the lower surface 11b of the wafer holding member 11 made of ceramic, molybdenum (Mo) -manganese (Mn), tungsten (W) -manganese (Mn), copper (Cu) -titanium (Ti), silver (Ag) -copper ( A metal layer 13 having a two-layer structure of a metallization layer such as Cu) -titanium (Ti) and a nickel (Ni) plating layer deposited on the metallization layer is deposited, and the brazing material 14 is applied to the metal layer 13. The introduction pipe 12 is joined via the.
[0006]
Further, the wafer holding member 11 electrically connects the mounting surface 11a on which the semiconductor wafer 21 on the upper surface is mounted with the introduction tube 12 joined to the lower surface 11b, so that the semiconductor wafer 21 on the mounting surface 11a can be electrically connected. The presence or absence is electrically confirmed through a metal introduction pipe 12. Conduction between the mounting face 11a and the introduction pipe 12 is made possible depending on thereby extending the metal layer 13 on the inner surface of the through hole 11c of the wafer holding member 11.
[0007]
In addition, there is a problem in that the stress at the time of bonding remains in the bonded portion between the wafer holding member 11 and the introduction tube 12 due to the difference in thermal expansion between the two members, and the bonded portion is easily peeled off. For this measure, a stress-reducing ceramic ring 15 made of a material having a thermal expansion coefficient close to that of the ceramic forming the wafer holding member 11 is brazed to the back surface 12b of the flange 12a formed at the upper end of the introduction pipe 12. And the stress which arises at the time of brazing can be relieved by pinching | interposing the metal introduction pipe | tube 12 from which a thermal expansion coefficient differs with the ceramic holding members 11 and the ceramic ring 15. FIG. As a result, the introduction tube 12 can be prevented from being peeled off from the wafer holding member 11 due to stress.
[0008]
Further, an extension metal tube 16 is welded to the lower end surface of the introduction tube 12 after joining with the wafer holding member 11 so that an inert gas can be easily introduced from the outside.
[0009]
[Problems to be solved by the invention]
However, in the conventional wafer holding apparatus, the introduction tube 12 is bonded to the metal layer 13 a around the opening on the lower surface 11 b side of the through hole 11 c of the wafer holding member 11 through the brazing material 14. The At this time, as shown in FIG. 4, the thickness a of the metal layer 13 is reduced by the surface tension in the opening on the lower surface 11b side of the through hole 11c. Therefore, when an external force is applied to the introduction pipe 12 during welding or transportation of the metal pipe 16, stress concentrates on a thin portion of the metal layer 13, and a crack in the thickness direction is generated in the metal layer 13, so that the metal layer 13 is formed. There was a problem that it was cut to cause poor conduction.
[0010]
In addition, as shown in FIG. 5, even when planar chamfering (C surface) processing is performed on the opening on the lower surface 11b side of the through hole 11c, the metal layer 13 in the chamfered portion has a reduced thickness a and stress is concentrated. In some cases, the above-mentioned problem may occur due to an easy shape.
[0011]
Therefore, the present invention has been completed in view of the above-described conventional problems, and an object of the present invention is to improve the electrical conduction structure between the wafer mounting surface of the wafer holding member and the introduction tube, and to mount the wafer. It is to be able to confirm the presence / absence of a wafer on the mounting surface with good and high reliability over a long period of time.
[0012]
[Means for Solving the Problems]
The wafer holding device of the present invention has a ceramic wafer holding member having a mounting surface on which an upper surface is mounted and a through hole penetrating between the upper and lower surfaces, and a flange formed at the upper end. in a wafer holding device the collar portion is provided with said lower surface side opening of brazed around a metal that is joined coaxially to the through hole inert gas inlet tube of the through-hole with there, the wherein the through hole is chamfered portion that is circularly arcuate curved surface on the bottom side opening is provided, and a front mounting surface wherein the inert gas introduction pipe metal layer for electrically conducting is from the inner surface of the through hole characterized that you have provided continuously over the periphery of the lower surface opening through said chamfered portion.
Preferably, in the wafer holding device of the present invention, the chamfered portion is an arcuate curved surface having a radius of curvature of 1 mm or more and a thickness of the wafer holding member or less.
Preferably, in the wafer holding device of the present invention, a ceramic ring is brazed to the back surface of the flange portion where the inert gas introduction pipe is brazed to the wafer holding member.
[0013]
In the present invention, the above structure improves the conduction structure between the wafer mounting surface of the wafer holding member and the inert gas introduction tube, and it is good for a long time to electrically check the presence or absence of the wafer on the mounting surface. It has the effect of becoming able to.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The wafer holding apparatus of the present invention will be described in detail below. FIG. 1 is a cross-sectional view showing an example of an embodiment of a wafer holding device of the present invention. In FIG. 1, reference numeral 11 denotes a wafer holding member, 11 a denotes a wafer mounting surface on the upper surface of the wafer holding member 11, and 11 b denotes a lower surface of the wafer holding member 11 on the side where the introduction pipe is joined. Reference numeral 11c denotes a gas introduction through-hole penetrating between the upper and lower surfaces of the wafer holding member 11, reference numeral 12 denotes an introduction pipe, reference numeral 13 denotes a metal layer, reference numeral 13a denotes a metal layer joined to the flange 12a of the introduction pipe 12, and reference numeral 13b denotes It is a metal layer on the inner surface of the through hole 11c. Further, 14 is a brazing material, and 15 is a ceramic ring for stress relaxation. 1 to 3 showing the present invention, the same parts as those in FIG.
[0015]
The wafer holding apparatus of the present invention includes a ceramic wafer holding member 11 having a mounting surface 11a on the upper surface and a through hole 11c penetrating between the upper and lower surfaces, and a flange 12a at the upper end. Are formed, and the flange portion 12a is brazed around the opening on the lower surface 11b side of the through hole 11c and is coaxially joined to the through hole 11c, and the upper end portion of the introduction tube 12 And a ceramic ring 15 brazed to the back surface of the flange 12a.
[0016]
As shown in FIG. 1, the wafer holding member 11 has a disk shape made of ceramics, and has a flat mounting surface 11a on which a semiconductor wafer such as Si or GaAs or a wafer such as a glass substrate for liquid crystal is mounted on the upper surface. And has a through hole 11c that allows the placement surface 11a and the lower surface 11b to communicate with each other. The flange portion 12a of the introduction tube 12 is brazed and joined to the lower surface 11b of the wafer holding member 11 around the opening on the lower surface 11b side of the through hole 11c. A specific joining structure between the wafer holding member 11 and the introduction tube 12 is such that a metal layer 13a having a two-layer structure of a metallized layer and a metal plating layer is formed on the lower surface 11b of the wafer holding member 11, and the brazing material 14 is used. In this structure, the flange 12a at the upper end of the introduction pipe 12 is brazed.
[0017]
Then, when a wafer is placed on the placement surface 11a of the wafer holding member 11 and an inert gas such as helium (He) is introduced from the introduction tube 12, it is inert to a number of grooves formed on the placement surface 11a. Gas accumulates, heat transfer between the wafer and the mounting surface 11a is improved, and generation of a large heat distribution on the wafer can be suppressed.
[0018]
The wafer holding member 11 and the introduction tube 12 are joined to each other between planes, so that the brazing material 14 can be filled in a wide range, and a great effect can be obtained for preventing gas leakage.
[0019]
Further, the thickness t of the flange portion 12a (joint portion) of the introduction tube 12 to be brazed to the wafer holding member 11 is preferably 0.1 to 1 mm, and the width d of the flange portion 12a is preferably 1 mm or more. If t exceeds 1 mm, deformation of the flange portion 12a is difficult to occur during brazing and stress relaxation becomes insufficient, so that the stress generated in the wafer holding member 11 increases and the ceramic wafer holding member 11 is easily broken. Become. If t is less than 0.1 mm, the strength of the flange 12a will be insufficient. On the other hand, if d is less than 1 mm, the airtightness due to bonding becomes insufficient and the inert gas tends to leak.
[0020]
Since the material of the introduction tube 12 is a metal material close to the thermal expansion coefficient of ceramics, it is preferable to use Fe—Ni—Co alloy, Mo, Pt, Ti, Nb, or the like.
[0021]
The material of the brazing material 14 is preferably a material that does not melt or liquefy at a high temperature (400 to 600 ° C.), and is preferably a brazing material such as an Ag—Cu alloy system, an Ag system, or an Au system.
[0022]
The material of the wafer holding member 11 is mainly composed of one or more of alumina (Al ₂ O ₃ ), aluminum nitride (AlN), zirconia (ZrO ₂ ), silicon carbide (SiC), and silicon nitride (Si ₃ N ₄ ). It is ceramics. In particular, from the viewpoint of plasma resistance, it contains 99% by weight or more of high-purity alumina as a main component and contains sintering aids such as silicon dioxide (SiO ₂ ), magnesium oxide (MgO), and calcium oxide (CaO). Alumina ceramics, aluminum nitride ceramics mainly containing aluminum nitride and containing Group 2a element oxides and Group 3a element oxides in the periodic table in the range of 0.5 to 20% by weight, AlN of 99% by weight or more Any of high-purity aluminum nitride ceramics containing as a main component is suitable. Since these are unlikely to react chemically unlike metal materials, there is an advantage that contamination of the semiconductor wafer by metal elements can be reduced.
[0023]
Furthermore, a stress-reducing ceramic ring 15 is brazed to the back surface 12b of the flange portion 12a of the introduction tube 12. Specifically, similarly to the brazing of the wafer holding member 11 and the introduction tube 12, a metal layer 13 is formed on the upper surface of the ceramic ring 15, and the back surface 12 b of the flange 12 a of the introduction tube 12 is formed by the brazing material 14. Braze to.
[0024]
In the present invention, the through hole 11c is provided with a chamfered portion A (FIG. 2) having an arcuate curved surface having a radius of curvature of 1 mm or more and less than the thickness of the wafer holding member 11 at the opening on the lower surface 11b side. The distance in the radial direction between the inner peripheral surface and the starting point P (FIG. 3) on the lower surface 11b side of the chamfered portion A is 2 mm or less.
[0025]
That is, as shown in FIG. 2, the thickness of the metal layer 13 is reduced at the opening on the lower surface 11b side of the through hole 11c by chamfering the opening on the lower surface 11b side of the through hole 11c into an arcuate curved surface. It can be uniform overall. As a result, when an external force is applied to the introduction pipe 12 during welding or transportation of the metal pipe 16, the stress concentration on the thin portion of the metal layer 13 is eliminated, and the metal layer 13 is cracked in the thickness direction. Will not occur, and the metal layer 13 will not be cut off, resulting in poor conduction.
[0026]
If the curvature radius of the chamfered portion A of the opening on the lower surface 11b side of the through hole 11c is less than 1 mm, the thickness of the metal layer 13 in the chamfered portion is increased by the surface tension when the conductive paste for forming the metal layer 13 is applied. The thickness is reduced, and variations in thickness are likely to occur. Further, when the chamfered portion A has a radius of curvature exceeding the thickness of the wafer holding member 11, the angle formed between the inner surface of the through hole 11c and the mounting surface 11a is an acute angle at the mounting surface 11a side opening of the through hole 11c. The strength of the opening portion on the mounting surface 11a side of 11c is insufficient, and chipping or the like is likely to occur.
[0027]
Moreover, it is preferable that the thickness of the metal layer 13 having a two-layer structure of the metallized layer and the metal plating layer is 5 to 30 μm. When the thickness is less than 5 μm, the adhesion strength of the metal layer 13 is reduced due to the erosion of the brazing material 14, so that leakage of inert gas is likely to occur. If it is thicker than 30 μm, the stress applied to the metal layer 13 increases due to the difference in thermal expansion coefficient between the metal layer 13 and the ceramic, and the metal layer 13 tends to crack. The metal layer 13 is formed of a two-layer structure of a metallized layer made of Mo—Mn, W—Mn, Cu—Ti, Ag—Cu—Ti, and the like and a Ni plating layer.
[0028]
3 is an enlarged cross-sectional view in which the brazing portion at the upper end portion of the introduction tube 12 is enlarged. A stress-reducing ceramic ring 15 is brazed to the back surface 12b of the flange portion 12a of the introduction tube 12. . The ceramic ring 15 is preferably made of a ceramic material such as alumina ceramic or aluminum nitride ceramic having the same or similar thermal expansion coefficient as the ceramic forming the wafer holding member 11. The ceramic ring 15 can relieve stress generated during brazing by sandwiching the introduction tube 12 having different thermal expansion from the wafer holding member 11, and can prevent the introduction tube 12 from peeling off from the wafer holding member 11. In particular, the ceramic ring 15 is preferably made of the same ceramic as the wafer holding member 11.
[0029]
In the present invention, the radial distance between the inner peripheral surface of the ceramic ring 15 and the starting point P (FIG. 3) on the lower surface 11b side of the chamfered portion A of the through hole 11c is 2 mm or less. That is, as shown in FIG. 3, connecting the inner diameter R1 of the ceramic rings 15, the other starting P in the symmetrical positions to the center of the through hole 11c with respect to the start point P and its Ru Ah of the lower surface 11b side of the chamfered portion A The difference from the diameter R2 determined by the straight line is 4 mm or less, that is, the difference at one starting point P is 2 mm or less. If it exceeds 2 mm, the stress relaxation during brazing due to the introduction tube 12 being sandwiched between the wafer holding member 11 and the ceramic ring 15 becomes insufficient.
[0030]
In addition, the difference between the outer diameter of the ceramic ring 15 and the outer diameter of the flange 12a of the introduction pipe 12 is preferably 2 mm or less. When the outer diameter of the ceramic ring 15 becomes smaller than 2 mm than the outer diameter of the flange 12a of the introduction pipe 12, the stress during brazing due to the introduction pipe 12 being sandwiched by the ceramic ring 15 becomes insufficient. Further, when the outer diameter of the ceramic ring 15 is larger than the outer diameter of the flange 12a of the introduction tube 12 by 2 mm, the brazing material flows out between the lower surface 11b of the wafer holding member 11 and the ceramic ring 15, and a lump. A so-called brazing material pool is formed, and the wafer holding member 11 and the ceramic ring 15 are easily damaged. In order to effectively prevent the formation of such a brazing material pool, it is preferable to chamfer the outer peripheral end of the flange portion 12a of the ceramic ring 15 so that a smooth meniscus of the brazing material can be formed and stress is applied. Alleviated.
[0031]
The thickness of the ceramic ring 15 is preferably 1 mm or more. If it is less than 1 mm, the effect of stress relaxation during brazing becomes insufficient, and more preferably 5 mm or more. The upper limit is not particularly limited, but may be within a range that is acceptable in terms of practical structure.
[0032]
The wafer holding device of the present invention can be suitably used when holding a semiconductor wafer in a semiconductor manufacturing process. In addition to this, various wafers such as a glass substrate for liquid crystal in a manufacturing process of a liquid crystal display device. Can also be used.
[0033]
【The invention's effect】
The present invention includes a ceramic wafer holding member having a mounting surface for mounting a wafer on an upper surface and a through-hole penetrating between upper and lower surfaces, and a flange portion having a flange portion formed on an upper end. wafer holding member but includes a lower surface metal inlet tube is joined coaxially brazed in the through-hole around the opening of the through hole, the lower surface side opening of the through-hole radius of curvature 1mm or more A chamfered portion having an arcuate curved surface that is less than or equal to the thickness of the metal layer is provided. the Rukoto provided continuously over the circumference of the side opening, conducting structure of the introduction tube and the mounting surface of the wafer on the wafer holding member is improved, can be confirmed electrically presence of the wafer on the mounting surface To be good over the long term It has an action effect say.
[0034]
That is, the conductive paste for forming the metal layer for brazing the flange portion of the introduction pipe around the opening on the lower surface side of the through-hole eliminates the fact that the thickness of the conductor paste on the lower surface side of the through-hole is reduced due to the surface tension. Thus, the thickness of the metal layer becomes uniform. For this reason, it is possible to prevent stress concentration on the thin portion of the metal layer and prevent the occurrence of poor conduction due to the cutting of the metal layer. Therefore, it is possible to realize good conduction characteristics between the mounting surface of the wafer holding member and the introduction tube, and to electrically detect the presence or absence of the wafer on the mounting surface with good and high reliability over a long period of time. become able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an embodiment of a wafer holding device of the present invention.
2 is an enlarged cross-sectional view of a lower surface side opening of a through hole of a wafer holding member in the wafer holding device of FIG. 1;
3 is an enlarged cross-sectional view of a brazing portion of an introduction pipe in the wafer holding device of FIG. 1. FIG.
FIG. 4 is an enlarged cross-sectional view of a lower surface side opening of a through hole of a wafer holding member in a conventional wafer holding apparatus.
FIG. 5 is an enlarged cross-sectional view of a lower surface side opening of a through hole of a wafer holding member in another conventional wafer holding device.
FIG. 6 is a cross-sectional view showing an example of a conventional wafer holding device.
[Explanation of symbols]
11: Wafer holding member 11a: mounting surface 11b: lower surface 11c: through hole 12: inert gas introduction pipe 12a: flange 12b: back surface 13, 13a, 13b of flange: metal layer 14: brazing material 15: ceramic ring 16: Metal tube 21: Semiconductor wafer

Claims

A ceramic wafer holding member having a mounting surface for mounting a wafer on the upper surface and having a through-hole penetrating between the upper and lower surfaces, and a flange portion formed at the upper end, the flange portion passing through the through hole in a wafer holding apparatus and a the lower surface side opening metal which is brazed around are joined coaxially to said through-hole of the inert gas introduction pipe hole, the lower surface side opening of the through hole circle and arc curved surface are chamfered portion is provided, the metal layer for electrically connecting the front mounting surface and the inert gas inlet tube, the lower surface from the inner surface of the through hole through the chamfered portion wafer holding apparatus characterized that you have provided continuously over the circumference of the side opening.

2. The wafer holding apparatus according to claim 1, wherein the chamfered portion is an arcuate curved surface having a radius of curvature of 1 mm or more.

3. The wafer holding apparatus according to claim 1, wherein a ceramic ring is brazed to a back surface of the flange portion where the inert gas introduction pipe is brazed to the wafer holding member.