JP4454761B2

JP4454761B2 - Frost treatment method for glass product surface

Info

Publication number: JP4454761B2
Application number: JP2000050115A
Authority: JP
Inventors: 洋一郎丸子; 徹瀬川; 龍弘佐藤
Original assignee: Shin Etsu Quartz Products Co Ltd
Current assignee: Shin Etsu Quartz Products Co Ltd
Priority date: 2000-02-25
Filing date: 2000-02-25
Publication date: 2010-04-21
Anticipated expiration: 2020-02-25
Also published as: JP2001240429A

Description

【０００１】
【発明の属する技術分野】
本発明は、ガラス製品、例えば、半導体製造用石英ガラス治具（チューブ、炉心管、ボート等）、特に長さ１０００mmを超える大型製品の表面を均一にフロスト処理することのできる新規な方法並びに表面に凹凸ある粗面をムラなく形成した石英ガラスチューブに関する。
【０００２】
【関連技術】
ガラス製品、特に石英ガラス製品は、高純度・耐熱性・耐化学薬品性に優れ、近年は半導体製造用治具、例えばチューブ、炉心管、ボード等として広く用いられている。
【０００３】
しかしながら、石英ガラス製品の問題点として次の点が指摘されている。▲１▼赤外線等による輻射熱が石英治具を伝搬しその端部のシール部材や連結用の有機物材料を劣化させる（特公平８−２４１０９号公報）。▲２▼LPCVＤ（Low Pressure Chemical Vapor Deposition）法によるポリシリコン膜成長時に炉心管内表面に堆積が起こり、それがウェーハの熱処理時に剥離する（実開昭６１−８８２３３号公報）。▲３▼熱処理時に石英ガラスボートとウェーハの融着がおこる（特開平１−１７００１９号公報）。
【０００４】
これらの問題点の改善策としては、石英ガラス製品の表面に凹凸を設けることが行われる。この石英ガラス製品の表面に凹凸をつけることにより、▲１▼熱の遮断効果、▲２▼熱処理時のパーティクル防止（剥離を防ぐ）及び▲３▼熱処理時のボートとウェーハの融着防止という効果を期待することができ、上記した石英ガラス製品の問題点を解消することが可能となる。
【０００５】
石英ガラス製品の表面の凹凸の形成にはサンドブラスト法と化学的薬液処理法がある。一般的には機械的に表面を破壊する技術であるサンドブラスト法が用いられている。このサンドブラスト法による表面処理は、従来から石英ガラス製品の表面に凹凸な粗面を作る技術として、薬液処理法よりもむしろ一般的な技術として存在していた。
【０００６】
このサンドブラスト法の問題点は、表面の凹凸面にマイクロクラック（〜Max１００μm）ができ、石英ガラス製品にダメージを加えることになることである。つまり、マイクロクラックが生成すると、▲１▼マイクロクラックに汚染物質が入り、▲２▼マイクロクラックによるガラスの強度劣化、及び▲３▼サンドブラスト処理後のフッ酸エッチングによる寸法精度のずれ、という不都合が生じてしまう。
【０００７】
例えば、図７及び図８に示すような処理槽１０を用い、該処理槽１０内に設置された固定治具１２に石英ガラス製品１４を斜めに、例えば１０度〜３０度程度傾斜させた状態で固定し、薬液供給口１６から薬液１８を処理槽１０に供給し、該石英ガラス製品１４の全体を薬液１８に浸漬し、その後所定時間浸漬を継続することによって石英ガラス製品の表面に凹凸を形成することが一般的に行われている。
【０００８】
薬液による表面処理は、従来から石英ガラス表面に凹凸な粗面を作る技術として知られている。例えば、フッ化水素とフッ化アンモニウムと酢酸と水の混合溶液で処理する方法が提案されている（特開平７−２６７６７９号公報）。
【０００９】
フロスト加工（つや消加工）の原理については、「ガラスの辞典」（作花済夫編集、３０頁、朝倉書店１９８５年発行）に次のように説明されている。フッ酸にフッ化アンモニウム（ＮＨ₄Ｆ）を加えた腐食液でガラスをエッチングすると、
【００１０】
【化１】

【００１１】
の反応よりケイフッ化アンモニウムが生成し、ガラス表面に沈殿するので、フッ酸による侵食が妨げられる。これとフッ酸の侵食の重畳により凹凸ができる。
【００１２】
現在のところ、化学的薬液処理法は半導体工業で必要とされる凹凸を作るのに最適であると考えられており、また、薬液の成分としては、フッ化水素とフッ化アンモニウムと酢酸と水の混合溶液が好適であることが知られている（特開平７−２６７６７９号公報）。この薬液組成の範囲は、ＨＦ：５〜４０重量％、ＮＨ₄Ｆ：５〜４０重量％、ＣＨ₃ＣＯＯＨ：１０〜６０重量％、Ｈ₂Ｏ：１０〜５０重量％で行うのが好ましい。
【００１３】
【発明が解決しようとする課題】
しかし、薬液処理法では、しばしばガラス表面に凹凸のムラができる、つまり、面粗さにムラができるという問題がある。具体的には、凹凸ができない箇所ができたり、凹凸の深さがまちまちになってしまう。ムラのない均一な凹凸を作るためには、薬液成分の存在比だけでは不十分である。製品サイズが大きくなり、処理槽が大型化するに従い、このムラの発生状況が顕著となってきていた。特に１０００mmを超える大型石英ガラスチューブ等を処理する場合、チューブの内外面、左右両端、中央部で、凹凸の分布が生じる。具体的には、処理槽の薬液供給口に近い表面粗さが小さく、供給口から離れるほど表面粗さが大きくなるものであった。
【００１４】
本発明は、上記した従来の薬液処理法の問題点に鑑みなされたもので、ガラス製品、例えば石英ガラス製品の表面に形成される凹凸状態の差を極めて小さくすること、具体的には石英ガラス製品の内外面、左右両端、中央部の表面粗さの差を極めて小さくすることができ、例えば半導体製造用石英ガラス治具（チューブ、炉心管、ボート等）、特に長さ１０００ｍｍを超える大型製品の表面を均一にフロスト処理することのできるガラス製品表面のフロスト処理方法及び表面に凹凸ある粗面をムラなく形成した石英ガラスチューブを提供することを目的とする。
【００１５】
【課題を解決するための手段】
上記課題を解決するために、本発明のガラス製品表面のフロスト処理方法は、処理槽を用いてガラス製品をフロスト処理用薬液に浸漬させることによってガラス製品表面にフロスト処理を行う方法であって、該ガラス製品に該フロスト処理用薬液が最初に接触する際、下記式（１）で定義されるレイノルズ数Ｒｅが４０００以上の範囲になるように薬液の流速ｕを制御することにより薬液の流動を制御し、ガラス製品全体を薬液に浸漬した後は薬液の流れを止め、静置で処理を行うことを特徴とする。
【００１６】
【数３】
Ｒｅ＝Ｄ・ｕ・ρ／μ・・・（１）
〔式（１）において、Ｄ：処理槽の幅、ｕ：薬液の流速、ρ：薬液の密度、μ：薬液の粘度〕
【００１７】
本ガラス製品表面のフロスト処理方法は、処理槽を用いてガラス製品をフロスト処理用薬液に浸漬させることによってガラス製品表面にフロスト処理を行う方法であって、該ガラス製品に該フロスト処理用薬液が最初に接触する際、下記式（１）で定義されるレイノルズ数Ｒｅが４０００以上の範囲になるように薬液の流速ｕを制御することにより薬液の流動を制御し、ガラス製品全体を薬液に浸漬した後は、薬液の流れをレイノルズ数Ｒｅが２１００以下に制御した状態を保持しつつ処理を行うことを特徴とする。
【００１８】
【数４】
Ｒｅ＝Ｄ・ｕ・ρ／μ・・・（１）
〔式（１）において、Ｄ：処理槽の幅、ｕ：薬液の流速、ρ：薬液の密度、μ：薬液の粘度〕
【００１９】
上記本発明方法の２つの態様において、上記ガラス製品に上記フロスト処理用薬液が最初に接触する際の薬液の流動レイノルズ数Ｒｅを４０００以上に制御する好ましい手段としては、▲１▼処理槽に攪拌機を設置し、該攪拌機の回転数を制御すること、つまり、攪拌翼によって処理槽内を攪拌すること、▲２▼処理槽に複数の薬液供給口を設け、該薬液供給口からの薬液の流速を制御すること、▲３▼処理槽にバブリング装置を設置し、該バブリング装置の空気圧力を制御すること、をあげることができる。上記▲３▼はバブリング法といえるもので、薬液内に気体（泡）を投入することによって流れを作るもので、例えるならば金魚の水槽のごときものである。
【００２０】
レイノルズ数Ｒｅを４０００以上に制御する手段としては、上記した▲１▼〜▲３▼の他に、▲４▼シャワーリング法、つまり、薬液をシャワーによって処理槽に送り込むこと、▲５▼振動法、つまり、製品又は薬液に機械的振動を与えること、▲６▼処理槽の構造を、薬液が循環するようなシステムを備えたものとすること、等をあげることができる。
【００２１】
処理槽を用いてガラス製品をフロスト処理用薬液に浸漬させる態様としては、処理槽にガラス製品を設置して、薬液を供給する際、正確には供給される薬液がガラス製品と接触する際の薬液の流動を制御する態様、または、逆に、予め処理槽に薬液を満たし、薬液の流動を制御した状態で、ガラス製品を処理槽内に投入する態様をあげることができる。さらに、両者の中間の態様として、ガラス製品を投入しつつ、薬液を供給する態様も適用可能である。要するに、本発明方法においては、ガラス製品が薬液と最初に接触する際に、薬液の流動を制御した状態とすればよいもので、そのような態様はすべて含まれるものである。
【００２２】
また、いずれの場合もガラス製品全体が薬液に接触した後は薬液の流動は停止し、静置で処理を行うか又は、ガラス製品全体が薬液に接触後、薬液の流動レイノルズ数Ｒｅを所定値（２１００）以下に制御した状態のまま保持し、処理を行う。
【００２３】
薬液の流動をレイノルズ数Ｒｅを４０００以上の範囲に制御すると、ガラス表面に形成されるケイフッ化アンモニウムの微結晶の核発生が成長よりも優先的に行われ、ガラス表面をマスクする微結晶のサイズが均一に保たれ、面粗さの均一な凹凸面の形成に寄与することとなる。
【００２４】
逆に流れの存在しない状態では、ケイフッ化アンモニウムの微結晶の核発生よりも成長が優先的に行われ、ガラス表面をマスクする微結晶が成長し、結果として面粗さの不均一な凹凸面が形成される。
【００２５】
上述したように、薬液の流動状態は最初の均一な核生成に効果をもたらすが、流動状態を継続すると、ガラス表面をマスクする微結晶が剥がれてしまい、面粗さの不均一を生み出す場合があり、流動の制御を慎重に行わなければならず、また長時間の流動を継続することは省エネルギーの観点からも好ましくない。
【００２６】
本発明方法は、石英ガラス製品のみならず、あらゆるガラス製品の化学的薬液処理の処理技術として有効である。本発明方法で用いられる薬液についても、フッ化水素とフッ化アンモニウムと酢酸と水の混合溶液に限らず、フッ化水素とフッ化アンモニウムとギ酸と水の混合溶液やフッ化水素とフッ化アンモニウムとプロピオン酸と水の混合溶液等も適用可能である。
【００２７】
本発明の長さ１０００mmを超える大型の石英ガラスチューブは、上記した本発明方法でフロスト処理された表面の凹凸状態の差が極めて少なく、具体的には、内面外面及び左右端面、中央部の表面粗さのＲａ値が０.１〜１μmでかつ各値の比が２倍を超えず、Ｒｍａｘ値が１〜１０μmでかつ各値の比が２倍を超えないことを特徴とする。
【００２８】
本発明の石英ガラスチューブは、例えばＳｉウェーハの表面に酸化膜や多結晶珪素膜をガス反応で形成するＣＶＤ装置や熱拡散装置などに使用される。石英ガラスチューブの平均表面粗さＲａが０．１μｍ未満では、表面が平滑になてしまいガスを使用した工程で用いた場合、ガスもしくはその反応生成物が表面に付着しにくく、最初に石英ガラス表面にガスもしくはその反応生成物を付着する必要があり、工程が煩雑でコスト高になる。
【００２９】
一方、平均表面粗さＲａが１μｍを超えると、ガスもしくはその反応生成物が異常に付着し、例えば反応炉内のガス反応に乱れが生じＳｉウェーハ上の反応生成物の蒸着量のコントロールが困難になる。
【００３０】
また、最大粗さＲｍａｘについても前述と同様に１μｍ未満ではガスもしくはその反応生成物の予めの付着が必要となり、最大粗さＲｍａｘが１０μｍを超えるとＳｉウェーハ上の反応生成物の蒸着量のコントロールが困難となる。
【００３１】
Ｒａ、Ｒｍａｘの各比が２倍を超えると、ガス反応中にガスもしくはその反応生成物の付着に分布が生じ、結果として反応炉内のガス反応に乱れが生じＳｉウェーハの反応生成物の蒸着量のコントロールが困難となる。
【００３２】
【発明の実施の形態】
以下に本発明方法を実施するのに用いられる処理槽の好ましい態様を添付図面中、図１〜図６とともに説明する。図１は本発明方法の実施に用いられる処理槽の１例を示す側面的説明図、図２は図１の上面的説明図、図３は本発明方法の実施に用いられる処理槽の他の例を示す側面的説明図、図４は図３の上面的説明図、図５は本発明方法の実施に用いられる処理槽の別の例を示す側面的説明図、図６は図５の上面的説明図である。
【００３３】
図１及び図２は、攪拌機付き処理槽１０Ａを示す。該処理槽１０Ａには、図７及び図８に示した従来の処理槽１０と同様に、石英ガラス製品１４を斜めに、例えば１０度〜３０度程度傾斜させた状態で固定する固定治具１２及びフロスト処理用薬液１８を供給する薬液供給口１６が、設置されている他に、新たに攪拌翼２０を備えた攪拌機２２が設けられている。この攪拌機２２を作動させることによって薬液供給口１６から供給される薬液の流動レイノルズ数Ｒｅを制御することができる。
【００３４】
図３及び図４は、複数の薬液供給口を設けた処理槽１０Ｂを示す。該処理槽１０Ｂには、図７及び図８に示した従来の処理槽１０と同様に、石英ガラス製品１４を斜めに固定する固定治具１２及びフロスト処理用薬液１８を供給する薬液供給口１６が設けられているが、その薬液供給口１６の他に新たに３つの薬液供給口１６ａ，１６ｂ，１６ｃが追加して設けられている。この薬液供給口１６，１６ａ〜１６ｃの設置数は図示例では４つの場合を示したが、２つ以上の複数設ければよいもので、例えば、６つや８つ設けることが可能である。この場合、薬液の均一な供給を行うためには各薬液供給口を互いに対称となる位置に設置するのが好適である。
【００３５】
図５及び図６は、バブリング装置付処理槽１０Ｃを示す。該処理槽１０Ｃには、図７及び図８に示した従来の処理槽１０と同様に、石英ガラス製品１４を斜めに固定する固定治具１２及びフロスト処理用薬液１８を供給する薬液供給口１６が設けられている他に、新たにバブリング装置２４が設けられている。該バブリング装置２４は処理槽１０Ｃの底面に設置された空気排出パイプ２６及び該空気排出パイプ２６に空気を導入する空気導入パイプ２８を有している。該空気排出パイプ２６には多数の空気排出孔が穿設されており、該空気導入パイプ２８を介して導入された空気が該空気排出口から薬液１８中に放出されて多数のバブル（泡）３０が発生するようになっている。
【００３６】
上記した各処理槽１０Ａ，１０Ｂ，１０Ｃは、従来と同様に、各処理槽１０Ａ〜１０Ｃ内に設置された固定治具１２に斜めに固定された石英ガラス製品１４の表面に凹凸を形成するために用いられる。
【００３７】
本発明方法の特徴は、処理槽を用いてガラス製品、例えば石英ガラス製品１４をフロスト処理用薬液１８に浸漬させることによってガラス製品１４の表面にフロスト処理を行うにあたり、該ガラス製品１４に該フロスト処理用薬液１８が最初に接触する際、下記式（１）で定義されるレイノルズ数Ｒｅが所定数値（４０００）以上の範囲になるように薬液１８の流速ｕを制御し、該ガラス製品１４の全体を薬液１８に浸漬した後は薬液１８の流れを止め、静置で処理するか、又は薬液１８の流れをレイノルズ数Ｒｅが所定数値（２１００）以下に制御した状態を保持しつつ処理を行うものである。
【００３８】
【数５】
Ｒｅ＝Ｄ・ｕ・ρ／μ・・・（１）
〔式（１）において、Ｄ：処理槽の幅、ｕ：薬液の流速、ρ：薬液の密度、μ：薬液の粘度〕
【００３９】
上記した薬液の流動レイノルズ数Ｒｅを所定数値以上又は以下に制御する場合に、図７及び図８に示した従来の処理槽１０の構造では充分な制御を行うことは不可能であり、図１〜図６に示した処理槽１０Ａ，１０Ｂ，１０Ｃを用い、処理槽１０Ａでは攪拌機２２により、処理槽１０Ｂでは、複数の薬液供給口１６，１６ａ〜１６ｃにより、及び処理槽１０Ｃではバブリング装置２４により、供給される薬液１８の流動状態、つまり、レイノルズ数を制御することによって本発明方法の実施を有効に実現することが可能となる。
【００４０】
【実施例】
以下に実施例をあげて本発明をさらに具体的に説明するが、これらの実施例は例示的に示されるもので限定的に解釈されるべきでないことはいうまでもない。
【００４１】
（実施例１）
図１及び図２に示した構造と同様の攪拌機付処理槽１０Ａ（６００×６００×１５００mm）にHERALUX-LA（信越石英株式会社製半導体工業用石英ガラスの商品名）によって作成した石英ガラスチューブ（φ４００×１２００mm）を固定治具１２にて斜めに固定し、攪拌機２２を回転しながら、４００リットルの薬液（組成ＨＦ：２５重量％、ＮＨ₄Ｆ：２５重量％、ＣＨ₃ＣＯＯＨ：２５重量％、Ｈ₂Ｏ：２５重量％の混合溶液）を供給口から注入し、１０分間で石英ガラスチューブ１４全体を薬液１８に浸漬させた。石英ガラスチューブ１４が薬液１８と最初に接触する際の流動制御は、槽内の攪拌機２２の回転数を制御することによって、Ｒｅ=５０００になるように調整した。石英ガラスチューブ１４全体が薬液１８に浸漬後、攪拌機２２を停止し、２時間静置にて保持することによって表面の凹凸を形成した。表面に凹凸を形成した石英ガラスチューブの表面粗さ（Ra及びRmax）の測定及び目視による表面状態の観測を行った。
【００４２】
表面粗さ（Ra及びRmax）の測定は、サーフコム３００B（株式会社東京精密製表面粗さ計）を用い、測定ポイントは石英ガラスチューブの左端面から５０mm、６００mm、１１５０mmの内面及び外面の６箇所に設定して行い、測定結果を表１〜３に示した。表面状態の観測結果は表４に示した。
【００４３】
（実施例２）
石英ガラスチューブが薬液と最初に接触する際の流動制御は、槽内の攪拌機の回転数を制御することによって、Ｒｅ=１６０００になるように調整した以外は、実施例１と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００４４】
（実施例３）
図１及び図２に示した攪拌機付処理槽１０Ａの代わりに図３及び図４に示した供給口を４箇所設けた処理槽１０Ｂを用い、薬液を４箇所の供給口１６，１６ａ，１６ｂ，１６ｃから注入した以外は実施例１と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００４５】
（実施例４）
石英ガラスチューブが薬液と最初に接触する際の流動制御は、供給口からの薬液の流速を制御することによって、Ｒｅ=１６０００になるように調整した以外は実施例３と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００４６】
（実施例５）
図１及び図２に示した攪拌機付処理槽１０Ａの代わりに図５及び図６に示した配管に多数の小孔を備えたバブリング装置付処理槽１０Ｃに石英ガラスチューブ１４を固定治具１２にて固定し、空気で処理槽内１０Ｃをバブリングしながら、実施例１と同一組成の薬液１８を供給口１６から注入し、１０分間で石英ガラスチューブ１４全体を薬液１８に浸漬させた。石英ガラスチューブ１４が薬液１８と最初に接触する際の流動制御は、バブリング装置２４の空気圧力を制御することによって、Ｒｅ=５０００になるように調整した。石英ガラスチューブ１４全体が薬液に浸漬後、バブリング装置２４を停止し、２時間静置にて保持することによって表面の凹凸を形成した。表面状態の評価及び観測を行い、その結果を表１〜４に示した。
【００４７】
（実施例６）
石英ガラスチューブ１４が薬液１８と最初に接触する際の流動制御は、バブリング装置２４の空気圧力を制御することによって、Ｒｅ=１６０００になるよう調整した以外は実施例５と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００４８】
（実施例７）
薬液組成をＨＦ：２５重量％、ＮＨ₄Ｆ：２５重量％、ＨＣＯＯＨ（ギ酸）：２５重量％、Ｈ₂Ｏ：２５重量％の混合溶液に変えた以外は実施例２と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００４９】
（実施例８）
薬液組成をＨＦ：２５重量％、ＮＨ₄Ｆ：２５重量％、Ｃ₂Ｈ₅ＣＯＯＨ（プロピオン酸）：２５重量％、Ｈ₂Ｏ：２５重量％の混合溶液に変えた以外は実施例１と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００５０】
（実施例９）
石英ガラスチューブ１４全体が薬液１８に浸漬後、攪拌機２２の回転数を制御することによって、Ｒｅ=２０００になるように調整し、Ｒｅ=２０００の状態で２時間保持しつつ表面の凹凸を形成した以外は実施例２と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００５１】
（実施例１０）
石英ガラスチューブ１４全体が薬液１８に浸漬後、バブリング装置２４の空気圧力を制御することによって、Ｒｅ=２０００になるように調整し、Ｒｅ=２０００の状態で２時間保持しつつ表面の凹凸を形成した以外は実施例５と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００５２】
（比較例１）
図７及び図８に示した処理槽１０を用い、かつ石英ガラスチューブが薬液と最初に接触する際の流動制御は、供給口１６からの薬液１８の流速を制御することによって、流動の小さい状態で詳しくはレイノルズ数Ｒｅ<２０００になるように調整した以外は実施例１と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００５３】
（比較例２）
石英ガラスチューブ１４が薬液１８と最初に接触する際の流動制御は、処理槽１０Ａ内の攪拌機２２の回転数を制御することによって、Ｒｅ=３０００になるよう調整した以外は実施例１と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００５４】
（比較例３）
石英ガラスチューブ１４全体が薬液１８に浸漬後、バブリング装置２４の空気圧力を制御することによって、レイノルズ数Ｒｅ=５０００になるように調整し、レイノルズ数Ｒｅ=５０００の状態で２時間保持しつつ表面の凹凸を形成した以外は実施例５と同様の実験手順を行った。処理した表面の凹凸状態の評価及び観測を行い、その結果を表１〜４に示した。
【００５５】
（比較例４）
実施例１で用いたものと同様の石英ガラスチューブの表面をサンドブラスト法により処理し、具体的には、φ２５０ｍｍのＳｉＣ粒子を石英ガラスチューブ表面に１時間吹き付けその表面に凹凸を形成した。処理した表面の凹凸状態の評価及び観測を実施例１と同様に行い、その結果を表１〜４に示した。
【００５６】
（比較例５）
表面に凹凸の形成の処理を行わない実施例１で用いたものと同様の石英ガラスチューブの表面状態の評価及び観測を実施例１と同様に行い、その結果を表１〜４に示した。
【００５７】
【表１】

【００５８】
【表２】

【００５９】
【表３】

【００６０】
【表４】

【００６１】
表１〜４に示された結果から明らかなように、実施例１〜１０の手法によって処理された石英ガラスチューブの表面の状態は表面粗さＲａ値が０．１〜１μｍでかつ各値の比が２倍を超えず、Ｒｍａｘ値が１〜１０μｍでかつ各値の比が２倍を超えていないものであり、表面粗さが所定範囲内に納まるとともに表面粗さの均一性も高く、良好な凹凸状態であることが確認された。また、表面状態の観測結果も凹凸面のむらがほとんどなく、良好な表面状態を示した。
【００６２】
比較例１〜４による石英ガラスチューブの表面の状態は表面粗さＲａ値が１μｍを超えたりあるいは各値の比が２倍を超え、Ｒｍａｘ値が１０μｍを超えたりあるいは各値の比が２倍を超えており、表面粗さが所定範囲内に納まらないとともに表面粗さも不均一であり、凹凸状態も不良であることがわかった。また、表面状態の観測結果も凹凸面のむらがあったり、粗い凹凸面になっている。また、比較例５の石英ガラスチューブは表面が凹凸面に全くなっていないものである。
【００６３】
【発明の効果】
以上述べたごとく、本発明方法によれば、ガラス製品、例えば石英ガラス製品の表面に形成される凹凸状態の差を極めて小さくすること、具体的には石英ガラス製品の内外面、左右両端、中央部の表面粗さの差を極めて小さくすることができ、例えば半導体製造用石英ガラス治具（チューブ、炉心管、ボート等）、特に長さ１０００ｍｍを超える大型製品の表面を均一にフロスト処理することのできるという大きな効果が達成される。
【００６４】
また、本発明の１０００mmを超える大型石英ガラスチューブは、内外面及び左右端面中央部の表面粗さの分布が極めて少ないという利点を有している。
【図面の簡単な説明】
【図１】本発明方法の実施に用いられる処理槽の１例を示す側面的説明図である。
【図２】図１の上面的説明図である。
【図３】本発明方法の実施に用いられる処理槽の他の例を示す側面的説明図である。
【図４】図３の上面的説明図である。
【図５】本発明方法の実施に用いられる処理槽の別の例を示す側面的説明図である。
【図６】図５の上面的説明図である。
【図７】従来の処理槽の側面的説明図である。
【図８】図７の上面的説明図である。
【符号の説明】
１０，１０Ａ，１０Ｂ，１０Ｃ：処理槽、１２：固定治具、１４：石英ガラス製品、１６，１６ａ，１６ｂ，１６ｃ：薬液供給口、１８：フロスト処理用薬液、２０：攪拌翼、２２：攪拌機、２４：バブリング装置、２６：空気排出パイプ、２８：空気導入パイプ、３０：バブル（泡）。[0001]
BACKGROUND OF THE INVENTION
The present invention provides a novel method and surface capable of uniformly frosting the surface of glass products, for example, quartz glass jigs for manufacturing semiconductors (tubes, furnace core tubes, boats, etc.), particularly large products exceeding 1000 mm in length. The present invention relates to a quartz glass tube in which a rough surface having irregularities is uniformly formed.
[0002]
[Related technologies]
Glass products, particularly quartz glass products, are excellent in high purity, heat resistance, and chemical resistance, and have been widely used in recent years as semiconductor manufacturing jigs such as tubes, furnace tubes, boards, and the like.
[0003]
However, the following points have been pointed out as problems with quartz glass products. {Circle around (1)} Radiant heat from infrared rays or the like propagates through the quartz jig and degrades the sealing member at the end and the organic material for connection (Japanese Patent Publication No. 8-24109). {Circle around (2)} Deposition occurs on the inner surface of the core tube during the growth of the polysilicon film by the LPCVD (Low Pressure Chemical Vapor Deposition) method, and it is peeled off during the heat treatment of the wafer (Japanese Utility Model Publication No. 61-88233). (3) The quartz glass boat and the wafer are fused during the heat treatment (Japanese Patent Laid-Open No. 1-170019).
[0004]
As an improvement measure for these problems, the surface of the quartz glass product is provided with irregularities. By providing irregularities on the surface of this quartz glass product, (1) heat blocking effect, (2) particle prevention during heat treatment (preventing peeling), and (3) boat and wafer fusion prevention during heat treatment Therefore, it is possible to eliminate the problems of the quartz glass product described above.
[0005]
There are two methods for forming irregularities on the surface of quartz glass products: sandblasting and chemical treatment. In general, a sand blast method, which is a technique for mechanically breaking the surface, is used. The surface treatment by the sand blast method has conventionally existed as a general technique rather than a chemical treatment method as a technique for producing an uneven rough surface on the surface of a quartz glass product.
[0006]
The problem with this sandblasting method is that microcracks (up to 100 μm) are formed on the irregular surface of the surface, which damages the quartz glass product. In other words, when microcracks are generated, (1) contaminants enter the microcracks, (2) strength deterioration of the glass due to microcracks, and (3) dimensional accuracy deviation due to hydrofluoric acid etching after sandblasting. It will occur.
[0007]
For example, the processing tank 10 as shown in FIGS. 7 and 8 is used, and the quartz glass product 14 is inclined at an angle of, for example, about 10 to 30 degrees on the fixing jig 12 installed in the processing tank 10. Then, the chemical solution 18 is supplied to the treatment tank 10 from the chemical solution supply port 16, and the entire quartz glass product 14 is immersed in the chemical solution 18, and then the immersion is continued for a predetermined time, thereby making the surface of the quartz glass product uneven. It is generally performed.
[0008]
The surface treatment with a chemical solution has been conventionally known as a technique for forming an uneven rough surface on a quartz glass surface. For example, a method of treating with a mixed solution of hydrogen fluoride, ammonium fluoride, acetic acid and water has been proposed (Japanese Patent Laid-Open No. 7-267679).
[0009]
The principle of frost processing (matte processing) is explained in “Glass Dictionary” (edited by Sakuo Sakuo, p. 30, published by Asakura Shoten in 1985) as follows. Etching glass with a corrosive solution containing ammonium fluoride (NH ₄ F) in hydrofluoric acid,
[0010]
[Chemical 1]

[0011]
As a result, ammonium silicofluoride is produced and precipitated on the glass surface, which prevents erosion by hydrofluoric acid. Unevenness is formed by superimposing this and the erosion of hydrofluoric acid.
[0012]
At present, chemical chemical treatment methods are considered to be optimal for creating irregularities required in the semiconductor industry, and chemical components include hydrogen fluoride, ammonium fluoride, acetic acid and water. It is known that this mixed solution is suitable (Japanese Patent Laid-Open No. 7-267679). It is preferable to carry out this chemical solution composition in the range of HF: 5 to 40% by weight, NH ₄ F: 5 to 40% by weight, CH ₃ COOH: 10 to 60% by weight, and H ₂ O: 10 to 50% by weight.
[0013]
[Problems to be solved by the invention]
However, the chemical treatment method often has a problem that irregularities are uneven on the glass surface, that is, the surface roughness is uneven. Specifically, a portion where the unevenness cannot be formed is formed, and the depth of the unevenness varies. In order to create uniform unevenness without unevenness, the abundance ratio of the chemical components is not sufficient. As the product size has increased and the treatment tank has become larger, the occurrence of this unevenness has become more prominent. In particular, when processing a large quartz glass tube exceeding 1000 mm, unevenness distribution occurs on the inner and outer surfaces, the left and right ends, and the central portion of the tube. Specifically, the surface roughness close to the chemical solution supply port of the treatment tank is small, and the surface roughness increases as the distance from the supply port increases.
[0014]
The present invention has been made in view of the above-described problems of the conventional chemical processing method, and it is possible to extremely reduce the difference in the uneven state formed on the surface of a glass product, for example, a quartz glass product, specifically, quartz glass. Differences in surface roughness between the inner and outer surfaces, left and right ends, and the center of the product can be extremely small. For example, quartz glass jigs for manufacturing semiconductors (tubes, furnace core tubes, boats, etc.), especially large products with a length exceeding 1000 mm An object of the present invention is to provide a frost treatment method for a glass product surface capable of uniformly frosting the surface of the glass product, and a quartz glass tube in which a rough surface having irregularities on the surface is uniformly formed.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, frosting method glassware surface of the present invention is a method of performing frosting processing glassware surface by dipping the frost treatment chemical glassware using the processing tank, when the frost treatment chemical to said glassware first contacts, the flow of the drug solution by controlling the flow rate u of the chemical as the Reynolds number Re is defined by the following formula (1) is in the range of 4000 or more After the entire glass product is soaked in the chemical solution, the flow of the chemical solution is stopped and the treatment is performed by standing still.
[0016]
[Equation 3]
Re = D · u · ρ / μ (1)
[In formula (1), D: width of treatment tank, u: flow rate of chemical solution, ρ: density of chemical solution, μ: viscosity of chemical solution ]
[0017]
Frost treatment method of the present glassware surfaces is a method of performing frosting processing glassware surface by dipping the frost treatment chemical glassware using the processing tank, the chemical solution for the frosting on the glassware When first contacting , the flow rate of the chemical solution is controlled by controlling the flow rate u of the chemical solution so that the Reynolds number Re defined by the following formula (1) is in the range of 4000 or more, and the entire glass product is immersed in the chemical solution. Thereafter, the processing is performed while maintaining the state in which the flow of the chemical solution is controlled to Reynolds number Re of 2100 or less.
[0018]
[Expression 4]
Re = D · u · ρ / μ (1)
[In formula (1), D: width of treatment tank, u: flow rate of chemical solution, ρ: density of chemical solution, μ: viscosity of chemical solution ]
[0019]
In the two aspects of the method of the present invention, as a preferable means for controlling the flow Reynolds number Re of the chemical solution when the frost treatment chemical solution first contacts the glass product to 4000 or more, (1) a stirrer in the treatment tank And controlling the number of revolutions of the stirrer, that is, stirring the inside of the treatment tank with the stirring blade, and (2) providing a plurality of chemical solution supply ports in the treatment tank, and the flow rate of the chemical solution from the chemical solution supply port And (3) installing a bubbling device in the treatment tank and controlling the air pressure of the bubbling device. The above (3) can be said to be a bubbling method, and a flow is created by introducing a gas (bubble) into the chemical solution. For example, it is a goldfish tank.
[0020]
As means for controlling the Reynolds number Re to 4000 or more, in addition to the above (1) to (3), (4) Showering method, that is, sending chemicals into the treatment tank by shower, (5) Vibration method That is, it is possible to give mechanical vibrations to the product or the chemical solution, and (6) to provide the structure of the treatment tank with a system for circulating the chemical solution.
[0021]
As an aspect of immersing the glass product in the chemical solution for frost treatment using the treatment tank, when the glass product is installed in the treatment tank and the chemical liquid is supplied, precisely when the supplied chemical liquid is in contact with the glass product An aspect of controlling the flow of the chemical liquid, or conversely, an aspect of filling the chemical liquid in the treatment tank in advance and controlling the flow of the chemical liquid to put the glass product into the treatment tank can be given. Furthermore, as an intermediate mode between the two, a mode in which a chemical solution is supplied while a glass product is introduced is also applicable. In short, in the method of the present invention, when the glass product first comes into contact with the chemical solution, the flow of the chemical solution may be controlled, and all such aspects are included.
[0022]
In any case, the flow of the chemical solution stops after the entire glass product has contacted the chemical solution, and the processing is carried out by standing or the flow Reynolds number Re of the chemical solution is set to a predetermined value after the entire glass product has contacted the chemical solution. (2100) The state controlled below is held and processing is performed.
[0023]
When the flow of the chemical is controlled to a Reynolds number Re in the range of 4000 or more, the nucleation of ammonium silicofluoride microcrystals formed on the glass surface is preferentially performed over the growth, and the size of the microcrystals masking the glass surface Is kept uniform and contributes to the formation of an uneven surface with uniform surface roughness.
[0024]
On the other hand, in the absence of flow, growth preferentially takes place over nucleation of ammonium silicofluoride microcrystals, resulting in the growth of microcrystals that mask the glass surface, resulting in uneven surfaces with uneven surface roughness. Is formed.
[0025]
As described above, the flow state of the chemical solution has an effect on the initial uniform nucleation, but if the flow state is continued, the crystallites masking the glass surface may be peeled off, resulting in uneven surface roughness. In addition, it is necessary to carefully control the flow, and continuing the flow for a long time is not preferable from the viewpoint of energy saving.
[0026]
The method of the present invention is effective as a processing technique for chemical chemical treatment of all glass products as well as quartz glass products. The chemical solution used in the method of the present invention is not limited to a mixed solution of hydrogen fluoride, ammonium fluoride, acetic acid and water, but a mixed solution of hydrogen fluoride, ammonium fluoride, formic acid and water, or hydrogen fluoride and ammonium fluoride. A mixed solution of propionic acid and water can also be applied.
[0027]
The large quartz glass tube having a length of 1000 mm of the present invention has a very small difference in unevenness of the surface frosted by the above-described method of the present invention, specifically, the inner surface and the left and right end surfaces, and the central surface. The roughness Ra value is 0.1 to 1 μm, the ratio of each value does not exceed twice, the Rmax value is 1 to 10 μm, and the ratio of each value does not exceed twice.
[0028]
The quartz glass tube of the present invention is used in, for example, a CVD apparatus or a thermal diffusion apparatus that forms an oxide film or a polycrystalline silicon film on the surface of a Si wafer by a gas reaction. If the average surface roughness Ra of the quartz glass tube is less than 0.1 μm, the surface becomes smooth and when used in a process using gas, the gas or its reaction product is difficult to adhere to the surface. It is necessary to attach a gas or its reaction product to the surface, which makes the process complicated and expensive.
[0029]
On the other hand, when the average surface roughness Ra exceeds 1 μm, the gas or its reaction product is abnormally attached, for example, the gas reaction in the reaction furnace is disturbed, and it is difficult to control the deposition amount of the reaction product on the Si wafer. become.
[0030]
Similarly, as described above, if the maximum roughness Rmax is less than 1 μm, it is necessary to deposit gas or its reaction product in advance. If the maximum roughness Rmax exceeds 10 μm, the deposition amount of the reaction product on the Si wafer is controlled. It becomes difficult.
[0031]
If the ratio of Ra and Rmax exceeds twice, the distribution of the gas or its reaction product is distributed during the gas reaction, resulting in disturbance of the gas reaction in the reaction furnace, and the deposition of the reaction product of the Si wafer. It becomes difficult to control the amount.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a treatment tank used for carrying out the method of the present invention will be described with reference to FIGS. 1 to 6 in the accompanying drawings. FIG. 1 is a side explanatory view showing an example of a processing tank used for carrying out the method of the present invention, FIG. 2 is a top explanatory view of FIG. 1, and FIG. 3 is another processing tank used for carrying out the method of the present invention. FIG. 4 is a top side explanatory view of FIG. 3, FIG. 5 is a side side explanatory view showing another example of a treatment tank used for carrying out the method of the present invention, and FIG. 6 is a top side view of FIG. FIG.
[0033]
1 and 2 show a processing tank 10A with a stirrer. In the processing tank 10A, as in the conventional processing tank 10 shown in FIGS. 7 and 8, the fixing jig 12 for fixing the quartz glass product 14 in an inclined state, for example, about 10 degrees to 30 degrees. In addition to the chemical solution supply port 16 for supplying the chemical solution 18 for frost treatment, a stirrer 22 having a new stirring blade 20 is provided. By operating the agitator 22, the flow Reynolds number Re of the chemical solution supplied from the chemical solution supply port 16 can be controlled.
[0034]
3 and 4 show a treatment tank 10B provided with a plurality of chemical solution supply ports. Similarly to the conventional processing tank 10 shown in FIGS. 7 and 8, the processing tank 10B has a fixing jig 12 for fixing the quartz glass product 14 at an angle and a chemical supply port 16 for supplying a chemical solution 18 for frost processing. However, in addition to the chemical liquid supply port 16, three new chemical

liquid supply ports

16a, 16b, and 16c are additionally provided. In the illustrated example, the number of the chemical

solution supply ports

16 and 16a to 16c is four, but two or more may be provided. For example, six or eight may be provided. In this case, in order to uniformly supply the chemical liquid, it is preferable to install the chemical liquid supply ports at positions that are symmetrical to each other.
[0035]
5 and 6 show a treatment tank 10C with a bubbling device. Similarly to the conventional processing tank 10 shown in FIGS. 7 and 8, the processing tank 10 </ b> C has a fixing jig 12 for obliquely fixing the quartz glass product 14 and a chemical supply port 16 for supplying a chemical solution 18 for frost processing. In addition to the above, a bubbling device 24 is newly provided. The bubbling device 24 has an air discharge pipe 26 installed on the bottom surface of the treatment tank 10 </ b> C and an air introduction pipe 28 for introducing air into the air discharge pipe 26. A large number of air discharge holes are formed in the air discharge pipe 26, and air introduced through the air introduction pipe 28 is discharged from the air discharge port into the chemical liquid 18 and a large number of bubbles (bubbles). 30 is generated.
[0036]
Each

processing tank

10A, 10B, and 10C described above is used to form irregularities on the surface of the quartz glass product 14 that is obliquely fixed to the fixing jig 12 installed in each processing tank 10A to 10C, as in the prior art. Used for.
[0037]
A feature of the method of the present invention is that when a glass product, for example, a quartz glass product 14 is immersed in a chemical solution 18 for frost treatment using a treatment tank, the surface of the glass product 14 is subjected to a frost treatment. When the treatment chemical solution 18 first contacts , the flow rate u of the chemical solution 18 is controlled so that the Reynolds number Re defined by the following formula (1) is in a range of a predetermined numerical value (4000) or more. After the whole is immersed in the chemical solution 18, the flow of the chemical solution 18 is stopped and the processing is performed by standing or the flow of the chemical solution 18 is processed while the Reynolds number Re is controlled to a predetermined value (2100) or less. Is.
[0038]
[Equation 5]
Re = D · u · ρ / μ (1)
[In formula (1), D: width of treatment tank, u: flow rate of chemical solution, ρ: density of chemical solution, μ: viscosity of chemical solution ]
[0039]
When the flow Reynolds number Re of the chemical solution is controlled to be greater than or less than a predetermined value, it is impossible to perform sufficient control with the structure of the conventional treatment tank 10 shown in FIGS. Using the

processing tanks

10A, 10B, and 10C shown in FIG. 6, the processing tank 10A by the stirrer 22, the processing tank 10B by the plurality of chemical

liquid supply ports

16, 16a to 16c, and the processing tank 10C by the bubbling device 24 It is possible to effectively implement the method of the present invention by controlling the flow state of the supplied chemical solution 18, that is, the Reynolds number.
[0040]
【Example】
The present invention will be described more specifically with reference to the following examples. However, it is needless to say that these examples are shown by way of illustration and should not be construed in a limited manner.
[0041]
Example 1
A quartz glass tube made of HEALUX-LA (trade name of quartz glass for semiconductor industry manufactured by Shin-Etsu Quartz Co., Ltd.) in a processing tank with a stirrer 10A (600 × 600 × 1500 mm) similar to the structure shown in FIGS. (400 mm x 1200 mm) is fixed obliquely by the fixing jig 12, and while rotating the stirrer 22, 400 liters of chemical solution (composition HF: 25% by weight, NH ₄ F: 25% by weight, CH ₃ COOH: 25% by weight) , H ₂ O: 25 wt% mixed solution) was injected from the supply port, and the entire quartz glass tube 14 was immersed in the chemical solution 18 for 10 minutes. The flow control when the quartz glass tube 14 first contacts the chemical solution 18 was adjusted to Re = 5000 by controlling the rotation speed of the stirrer 22 in the tank. After the entire quartz glass tube 14 was immersed in the chemical solution 18, the stirrer 22 was stopped, and the surface was unevenly formed by holding it for 2 hours. The surface roughness (Ra and Rmax) of the quartz glass tube with irregularities formed on the surface was measured and the surface condition was visually observed.
[0042]
Surface roughness (Ra and Rmax) is measured using Surfcom 300B (Tokyo Seimitsu Co., Ltd. surface roughness meter), and the measurement points are 6 locations on the inner and outer surfaces of 50mm, 600mm and 1150mm from the left end surface of the quartz glass tube. The measurement results are shown in Tables 1-3. The observation results of the surface state are shown in Table 4.
[0043]
(Example 2)
The flow control when the quartz glass tube first comes into contact with the chemical solution is the same experimental procedure as in Example 1 except that Re = 16000 is adjusted by controlling the rotation speed of the stirrer in the tank. went. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0044]
(Example 3)
Instead of the processing tank 10A with stirrer shown in FIGS. 1 and 2, a processing tank 10B provided with four supply ports shown in FIGS. 3 and 4 is used, and the chemical solution is supplied at four

supply ports

16, 16a, 16b, The same experimental procedure as in Example 1 was performed except that the injection was performed from 16c. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0045]
Example 4
The flow control when the quartz glass tube first comes into contact with the chemical solution is the same as that of Example 3 except that the flow rate of the chemical solution from the supply port is controlled so that Re = 16000. It was. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0046]
(Example 5)
In place of the processing tank 10A with a stirrer shown in FIGS. 1 and 2, the quartz glass tube 14 is fixed to the fixing jig 12 in the processing tank 10C with a bubbling device provided with a large number of small holes in the piping shown in FIGS. The chemical solution 18 having the same composition as in Example 1 was injected from the supply port 16 while bubbling the inside of the treatment tank 10C with air, and the entire quartz glass tube 14 was immersed in the chemical solution 18 for 10 minutes. The flow control when the quartz glass tube 14 first comes into contact with the chemical solution 18 was adjusted to Re = 5000 by controlling the air pressure of the bubbling device 24. After the entire quartz glass tube 14 was immersed in the chemical solution, the bubbling device 24 was stopped and held for 2 hours to form surface irregularities. The surface state was evaluated and observed, and the results are shown in Tables 1 to 4.
[0047]
(Example 6)
The flow control when the quartz glass tube 14 first comes into contact with the chemical solution 18 is the same experimental procedure as in Example 5 except that Re = 16000 is adjusted by controlling the air pressure of the bubbling device 24. It was. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0048]
(Example 7)
The experimental procedure was the same as in Example 2 except that the chemical composition was changed to a mixed solution of HF: 25% by weight, NH ₄ F: 25% by weight, HCOOH (formic acid): 25% by weight, and H ₂ O: 25% by weight. went. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0049]
(Example 8)
Example 1 except that the chemical composition was changed to a mixed solution of HF: 25% by weight, NH ₄ F: 25% by weight, C ₂ H ₅ COOH (propionic acid): 25% by weight, and H ₂ O: 25% by weight. A similar experimental procedure was performed. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0050]
Example 9
After the entire quartz glass tube 14 is immersed in the chemical 18, the rotation speed of the stirrer 22 is controlled to adjust to Re = 2000, and surface irregularities are formed while maintaining Re = 2000 for 2 hours. Except for this, the same experimental procedure as in Example 2 was performed. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0051]
(Example 10)
After the entire quartz glass tube 14 is immersed in the chemical solution 18, the air pressure of the bubbling device 24 is controlled to adjust to Re = 2000, and surface irregularities are formed while maintaining Re = 2000 for 2 hours. Except that, the same experimental procedure as in Example 5 was performed. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0052]
(Comparative Example 1)
The flow control when the processing tank 10 shown in FIGS. 7 and 8 is used and the quartz glass tube first comes into contact with the chemical solution is in a state where the flow is small by controlling the flow rate of the chemical solution 18 from the supply port 16. In detail, the same experimental procedure as in Example 1 was performed except that the Reynolds number Re <2000 was adjusted. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0053]
(Comparative Example 2)
The flow control when the quartz glass tube 14 first comes into contact with the chemical solution 18 is the same as in Example 1 except that the rotation speed of the stirrer 22 in the treatment tank 10A is adjusted so that Re = 3000. The experimental procedure was performed. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0054]
(Comparative Example 3)
After the entire quartz glass tube 14 is immersed in the chemical 18, the air pressure of the bubbling device 24 is controlled so that the Reynolds number Re = 5000, and the surface is maintained for 2 hours while maintaining the Reynolds number Re = 5000. The same experimental procedure as in Example 5 was performed except that the unevenness was formed. Evaluation and observation of the uneven | corrugated state of the processed surface were performed, and the result was shown to Tables 1-4.
[0055]
(Comparative Example 4)
The surface of the quartz glass tube similar to that used in Example 1 was treated by the sandblasting method. Specifically, φ250 mm SiC particles were sprayed on the quartz glass tube surface for 1 hour to form irregularities on the surface. Evaluation and observation of the uneven state of the treated surface were performed in the same manner as in Example 1, and the results are shown in Tables 1 to 4.
[0056]
(Comparative Example 5)
Evaluation and observation of the surface state of the quartz glass tube similar to those used in Example 1 in which the surface irregularity formation treatment was not performed were performed in the same manner as in Example 1, and the results are shown in Tables 1 to 4.
[0057]
[Table 1]

[0058]
[Table 2]

[0059]
[Table 3]

[0060]
[Table 4]

[0061]
As is clear from the results shown in Tables 1 to 4, the surface state of the quartz glass tube treated by the methods of Examples 1 to 10 has a surface roughness Ra value of 0.1 to 1 μm and each value. The ratio does not exceed 2 times, the Rmax value is 1 to 10 μm and the ratio of each value does not exceed 2 times, the surface roughness is within a predetermined range and the uniformity of the surface roughness is high, It was confirmed that the surface was in a good uneven state. In addition, the surface state observation result showed almost no uneven surface and a good surface state.
[0062]
The surface conditions of the quartz glass tubes according to Comparative Examples 1 to 4 are such that the surface roughness Ra value exceeds 1 μm, the ratio of each value exceeds 2 times, the Rmax value exceeds 10 μm, or the ratio of each value is twice. It was found that the surface roughness was not within the predetermined range, the surface roughness was non-uniform, and the uneven state was also poor. Also, the observation result of the surface state has uneven unevenness or rough unevenness. In addition, the quartz glass tube of Comparative Example 5 has no irregular surface at all.
[0063]
【The invention's effect】
As described above, according to the method of the present invention, the difference in unevenness formed on the surface of a glass product, for example, a quartz glass product, is extremely reduced, specifically, the inner and outer surfaces, both the left and right ends, the center of the quartz glass product. The difference in surface roughness of the parts can be made extremely small. For example, the surface of a quartz glass jig (tube, furnace core tube, boat, etc.) for manufacturing semiconductors, particularly large products exceeding 1000 mm in length, can be uniformly frosted. A great effect is achieved.
[0064]
Moreover, the large quartz glass tube exceeding 1000 mm of this invention has the advantage that distribution of the surface roughness of an inner-outer surface and the center part of right-and-left end surface is very small.
[Brief description of the drawings]
FIG. 1 is a side explanatory view showing an example of a processing tank used for carrying out the method of the present invention.
FIG. 2 is a top view for explaining FIG. 1;
FIG. 3 is a side explanatory view showing another example of a treatment tank used for carrying out the method of the present invention.
FIG. 4 is a top view for explaining FIG. 3;
FIG. 5 is a side explanatory view showing another example of a treatment tank used for carrying out the method of the present invention.
FIG. 6 is a top view for explaining FIG. 5;
FIG. 7 is a side view of a conventional treatment tank.
FIG. 8 is a top view for explaining FIG. 7;
[Explanation of symbols]
10, 10A, 10B, 10C: treatment tank, 12: fixing jig, 14: quartz glass product, 16, 16a, 16b, 16c: chemical solution supply port, 18: chemical solution for frost treatment, 20: stirring blade, 22: stirrer 24: bubbling device, 26: air discharge pipe, 28: air introduction pipe, 30: bubble.

Claims

A method of performing a frost treatment on the surface of a glass product by immersing the glass product in a chemical solution for frost treatment using a treatment tank, and when the chemical solution for frost treatment first contacts the glass product, the following formula (1 ), The flow rate of the chemical solution is controlled so that the Reynolds number Re is in the range of 4000 or more. After the entire glass product is immersed in the chemical solution, the flow of the chemical solution is stopped, A method for frosting a surface of a glass product, characterized in that the treatment is performed in a place.
[Expression 1]
Re = D · u · ρ / μ (1)
[In formula (1), D: width of treatment tank, u: flow rate of chemical solution, ρ: density of chemical solution, μ: viscosity of chemical solution ]

A stirrer is installed in the treatment tank to form the flow of the chemical solution when the chemical solution for frost treatment first contacts the glass product, and the flow Reynolds number Re of the chemical solution is set to 4000 by controlling the rotation speed of the stirrer. The method according to claim 1, wherein the method is controlled as described above, and after the entire glass product is immersed in the chemical solution, the flow of the chemical solution is stopped and the treatment is performed by standing still.

A chemical solution is provided by providing a plurality of chemical solution supply ports in the treatment tank and controlling a flow rate of the chemical solution from the chemical solution supply port in order to form a flow of the chemical solution when the frost treatment chemical solution first contacts the glass product. 2. The method according to claim 1, wherein the flow Reynolds number Re is controlled to 4000 or more, and after the entire glass product is immersed in the chemical solution, the flow of the chemical solution is stopped and the treatment is performed by standing still.

A bubbling device is installed in the treatment tank to form a flow of the chemical solution when the chemical solution for frost treatment first comes into contact with the glass product, and the flow Reynolds number Re of the chemical solution is controlled by controlling the air pressure of the bubbling device. Is controlled to 4000 or more, and after immersing the whole glass product in the chemical solution, the flow of the chemical solution is stopped and the method is carried out by standing still.

Any one method of claims 1-4, wherein the glass product is a quartz glass product.