JP2004137093A - Apparatus and method for controlling inert gas flow velocity in silicon single crystal pulling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enlarge the defect-free, high quality part of an ingot in the longitudinal direction. <P>SOLUTION: The lower end of the cylindrical part 37 of a heat insulating member 36 surrounding the outer circumferential surface of the ingot 25 is positioned above the surface of a silicon molten liquid 12 leaving a certain interval, a swelled part 41 is provided in the lower end inside the cylindrical part 37, and an inert gas supply and exhaust means makes an inert gas flow down between the swelled part 41 and the ingot 25. A plurality of flow straightening plates 43 which are respectively provided to vertically extend between the outer circumferential surface of the ingot 25 and the inner circumferential surface of the swelled part 41 and to freely move in parallel in the radial direction of the ingot 25 surround the outer circumferential surface of the ingot 25. A plurality of control plates 47 having respective base ends attached to the swelled part 41 and respective tip parts attached pivotally to the respective upper ends of a plurality of the flow straightening plates 43 close the gap between a plurality of the flow straightening plates 43 and the swelled part 41. The plurality of control plates 47 are respectively driven by a control plate driving means 50 in accordance with the change of the convection 12b of the silicon molten liquid 12 to control the solid-liquid boundary face 12c to be in an upward convex state. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、石英るつぼに貯留されたシリコン融液からシリコン単結晶のインゴット（以下、単にインゴットという。）を引上げるときの、不活性ガスの流速を制御する装置及びその方法に関するものである。
【０００２】
【従来の技術】
従来、シリコン単結晶の製造方法として、インゴットをチョクラルスキー法（以下、ＣＺ法という）により引上げる方法が知られている。このＣＺ法は、石英るつぼに貯留されたシリコン融液に種結晶を接触させ、石英るつぼ及び種結晶を回転させながら種結晶を引上げることにより、円柱状のインゴットを製造する方法である。
【０００３】
一方、半導体集積回路を製造する工程において、歩留りを低下させる原因として酸化誘起積層欠陥（Ｏｘｉｄａｔｉｏｎ−ｉｎｄｕｃｅｄ　Ｓｔａｃｋｉｎｇ　Ｆａｕｌｔ、以下、ＯＳＦという。）の核となる酸素析出物の微小欠陥や、結晶に起因したパーティクル（Ｃｒｙｓｔａｌ　Ｏｒｉｇｉｎａｔｅｄ　Ｐａｒｔｉｃｌｅ、以下、ＣＯＰという。）や、或いは侵入型転位（Ｉｎｔｅｒｓｔｉｔｉａｌ−ｔｙｐｅ　Ｌａｒｇｅ　Ｄｉｓｌｏｃａｔｉｏｎ、以下、Ｌ／Ｄという。）の存在が挙げられている。ＯＳＦは、結晶成長時にその核となる微小欠陥が導入され、半導体デバイスを製造する際の熱酸化工程等で顕在化し、作製したデバイスのリーク電流の増加等の不良原因になる。またＣＯＰは、鏡面研磨後のシリコンウェーハをアンモニアと過酸化水素の混合液で洗浄したときにウェーハ表面に出現する結晶に起因したピットである。このウェーハをパーティクルカウンタで測定すると、このピットも本来のパーティクルとともに光散乱欠陥として検出される。
【０００４】
このＣＯＰは電気的特性、例えば酸化膜の経時絶縁破壊特性（Ｔｉｍｅ　Ｄｅｐｅｎｄｅｎｔｄｉｅｌｅｃｔｒｉｃ　Ｂｒｅａｋｄｏｗｎ、ＴＤＤＢ）、酸化膜耐圧特性（Ｔｉｍｅ　Ｚｅｒｏ　Ｄｉｅｌｅｃｔｒｉｃ　Ｂｒｅａｋｄｏｗｎ、ＴＺＤＢ）等を劣化させる原因となる。またＣＯＰがウェーハ表面に存在するとデバイスの配線工程において段差を生じ、断線の原因となり得る。そして素子分離部分においてもリーク等の原因となり、製品の歩留りを低くする。更にＬ／Ｄは、転位クラスタとも呼ばれたり、或いはこの欠陥を生じたシリコンウェーハをフッ酸を主成分とする選択エッチング液に浸漬するとピットを生じることから転位ピットとも呼ばれる。このＬ／Ｄも、電気的特性、例えばリーク特性、アイソレーション特性等を劣化させる原因となる。この結果、半導体集積回路を製造するために用いられるシリコンウェーハからＯＳＦ、ＣＯＰ及びＬ／Ｄを減少させることが必要となっている。
【０００５】
このＯＳＦ、ＣＯＰ及びＬ／Ｄを有しない無欠陥のシリコンウェーハを切出すためのシリコン単結晶インゴットの製造方法が開示されている（例えば、特許文献１参照）。一般に、インゴットを速い速度で引上げると、インゴット内部に空孔型点欠陥の凝集体が支配的に存在する領域［Ｖ］が形成され、インゴットを遅い速度で引上げると、インゴット内部に格子間シリコン型点欠陥の凝集体が支配的に存在する領域［Ｉ］が形成される。このため上記製造方法では、インゴットを最適な引上げ速度で引上げることにより、上記点欠陥の凝集体が存在しないパーフェクト領域［Ｐ］からなるシリコン単結晶を製造できるようになっている。
【０００６】
【特許文献１】
米国特許第６，０４５，６１０号明細書に対応する特開平１１−１３９３号公報
【０００７】
【発明が解決しようとする課題】
しかし、上記従来の特許文献１に示されたシリコン単結晶インゴットの製造方法では、インゴットとシリコン融液との固液界面近傍での鉛直方向の温度勾配が均一になるように制御する必要があり、この制御はシリコン融液の残量の変化や対流の変化による影響を受けるため、インゴットの直胴部の長手方向に、無欠陥で高品質の部分を拡大することは困難であった。
本発明の目的は、引上げられるインゴットの無欠陥で高品質の部分をその長手方向に拡大できる、シリコン単結晶引上げ装置の不活性ガスの流速制御装置及びその流速制御方法を提供することにある。
【０００８】
【課題を解決するための手段】
請求項１に係る発明は、図１及び図５に示すように、チャンバ１１内に設けられシリコン融液１２が貯留された石英るつぼ１３と、石英るつぼ１３の外周面を包囲しシリコン融液１２を加熱するヒータ１８と、シリコン融液１２から引上げられるインゴット２５の外周面を包囲しかつ下端がシリコン融液１２表面から間隔をあけて上方に位置する筒部３７と筒部３７の下部内方に膨出して設けられた膨出部４１とを有する熱遮蔽部材３６と、チャンバ１１の上部からチャンバ１１の内部に不活性ガスを供給して膨出部４１とインゴット２５の間に不活性ガスを流下させる不活性ガス給排手段２８とを備えたシリコン単結晶引上げ装置の改良である。
【０００９】
その特徴ある構成は、インゴット２５の外周面と膨出部４１の内周面又はこの内周面の延長面との間に鉛直方向に延びかつインゴット２５の半径方向に平行移動可能にそれぞれ設けられ更にインゴット２５の外周面を包囲する複数の整流板４３，４４と、基端又は基部が膨出部４１にそれぞれ取付けられかつ先端に複数の整流板４３，４４の上端がそれぞれ枢着され更に複数の整流板４３，４４及び膨出部４１間の隙間を塞ぐ複数の調整板４７，４８と、シリコン融液１２の対流１２ｂの変化に応じて複数の整流板４３，４４をインゴット２５の外周面に近づけるか或いはインゴット２５の外周面から離すように複数の調整板４７，４８をそれぞれ駆動することによりインゴット２５とシリコン融液１２との固液界面１２ｃが上凸状となるように制御する調整板駆動手段５０とを備えたところにある。
【００１０】
請求項４に係る発明は、図１及び図５に示すように、シリコン融液１２を貯留する石英るつぼ１３を所定の回転速度で回転させ、シリコン融液１２から引上げられるインゴット２５を包囲しかつ下端がシリコン融液１２表面から間隔をあけて上方に位置する筒部３７と筒部３７の下部内方に膨出して設けられた膨出部４１とを有する熱遮蔽部材３６を設け、チャンバ１１の上部からチャンバ１１の内部に不活性ガスを供給して膨出部４１とインゴット２５の間に不活性ガスを流下させつつ、インゴット２５内が格子間シリコン型点欠陥の凝集体及び空孔型点欠陥の凝集体の存在しないパーフェクト領域となる引上げ速度でインゴット２５を引上げるシリコン単結晶引上げ方法の改良である。
その特徴ある構成は、インゴット２５の外周面と膨出部４１の内周面又はこの内周面の延長面との間に鉛直方向に延びかつインゴット２５の半径方向に平行移動可能にそれぞれ設けられた複数の整流板４３，４４がインゴット２５の外周面を包囲し、基端又は基部を膨出部４１にそれぞれ取付けかつ先端に複数の整流板４３，４４の上端をそれぞれ枢着した複数の調整板４７，４８が複数の整流板４３，４４及び膨出部４１間の隙間を塞ぎ、シリコン融液１２の対流１２ｂの変化に応じてインゴット２５の外周面に近づけるか或いはインゴット２５の外周面から離すように調整板駆動手段５０が複数の調整板４７，４８をそれぞれ駆動することによりインゴット２５とシリコン融液１２との固液界面１２ｃが上凸状となるように制御するところにある。
【００１１】
この請求項１に記載された不活性ガスの流速制御装置又は請求項４に記載された不活性ガスの流速制御方法では、インゴット２５の外周面及びシリコン融液１２の表面の境界部分であるメニスカス１２ａ近傍のシリコン融液１２に所定の対流１２ｂが発生しているときに、調整板駆動手段５０により複数の調整板４７，４８を駆動して、複数の整流板４３，４４をインゴット２５の外周面に近づけると、複数の整流板４３，４４及びインゴット２５間を流下する不活性ガスの流速が増大する。これによりメニスカス１２ａの表面を流下する不活性ガスの流速が増大するので、シリコン融液１２には、メニスカス１２ａ近傍で下降しかつシリコン融液１２及びインゴット２５間の固液界面１２ｃの中心近傍で上昇する比較的大きな対流１２ｂが発生し、固液界面１２ｃが上凸状になって、固液界面１２ｃの中心近傍の鉛直方向の温度勾配が大きくなる。この結果、固液界面１２ｃの中心近傍の鉛直方向の温度勾配と、固液界面１２ｃの周縁近傍の鉛直方向の温度勾配との差が小さくなるので、引上げられるインゴット２５の無欠陥で高品質の部分をその長手方向に拡大できる。
【００１２】
【発明の実施の形態】
次に本発明の第１の実施の形態を図面に基づいて説明する。
図５に本発明のシリコン単結晶引上げ装置１０を示す。この引上げ装置１０のチャンバ１１内には、シリコン融液１２を貯留する石英るつぼ１３が設けられ、この石英るつぼ１３の外周面は黒鉛サセプタ１４により被覆される。石英るつぼ１３の下面は上記黒鉛サセプタ１４を介して支軸１６の上端に固定され、この支軸１６の下部はるつぼ駆動手段１７に接続される。るつぼ駆動手段１７は図示しないが石英るつぼ１３を回転させる第１回転用モータと、石英るつぼ１３を昇降させる昇降用モータとを有し、これらのモータにより石英るつぼ１３が所定の方向に回転し得るとともに、上下方向に移動可能となっている。石英るつぼ１３の外周面は石英るつぼ１３から所定の間隔をあけてヒータ１８により包囲され、このヒータ１８は保温筒１９により包囲される。ヒータ１８は石英るつぼ１３に投入された高純度のシリコン多結晶体を加熱・融解してシリコン融液１２にする。
【００１３】
またチャンバ１１の上端には円筒状のケーシング２１が接続される。このケーシング２１には引上げ手段２２が設けられる。引上げ手段２２はケーシング２１の上端部に水平状態で旋回可能に設けられた引上げヘッド（図示せず）と、このヘッドを回転させる第２回転用モータ（図示せず）と、ヘッドから石英るつぼ１３の回転中心に向って垂下されたワイヤケーブル２３と、上記ヘッド内に設けられワイヤケーブル２３を巻取り又は繰出す引上げ用モータ（図示せず）とを有する。ワイヤケーブル２３の下端にはシリコン融液１２に浸してインゴット２５を引上げるための種結晶２４が取付けられる。
更にチャンバ１１にはこのチャンバ１１のインゴット側に不活性ガスを供給しかつ上記不活性ガスをチャンバ１１のるつぼ内周面側から排出するガス給排手段２８が接続される。ガス給排手段２８は一端がケーシング２１の周壁に接続され他端が上記不活性ガスを貯留するタンク（図示せず）に接続された供給パイプ２９と、一端がチャンバ１１の下壁に接続され他端が真空ポンプ（図示せず）に接続された排出パイプ３０とを有する。供給パイプ２９及び排出パイプ３０にはこれらのパイプ２９，３０を流れる不活性ガスの流量を調整する第１及び第２流量調整弁３１，３２がそれぞれ設けられる。
【００１４】
一方、引上げ用モータの出力軸（図示せず）にはエンコーダ（図示せず）が設けられ、るつぼ駆動手段１７には支軸１６の昇降位置を検出するエンコーダ（図示せず）が設けられる。２つのエンコーダの各検出出力はコントローラ（図示せず）の制御入力に接続され、コントローラの制御出力は引上げ手段２２の引上げ用モータ及びるつぼ駆動手段の昇降用モータにそれぞれ接続される。またコントローラにはメモリ（図示せず）が設けられ、このメモリにはエンコーダの検出出力に対するワイヤケーブル２３の巻取り長さ、即ちインゴット２５の引上げ長さが第１マップとして記憶される。また、メモリには、インゴット２５の引上げ長さに対する石英るつぼ１３内のシリコン融液１２の液面レベルが第２マップとして記憶される。コントローラは、引上げ用モータにおけるエンコーダの検出出力に基づいて石英るつぼ１３内のシリコン融液１２の液面を常に一定のレベルに保つように、るつぼ駆動手段１７の昇降用モータを制御するように構成される。
【００１５】
インゴット２５の外周面と石英るつぼ１３の内周面との間には、インゴット２５の外周面を包囲する熱遮蔽部材３６が設けられる。この熱遮蔽部材３６は円筒状に形成されヒータ１８からの輻射熱を遮る筒部３７と、この筒部３７の上縁に連設され外方に略水平方向に張り出すフランジ部３８とを有する。上記フランジ部３８を保温筒１９上に載置することにより、筒部３７の下縁がシリコン融液１２表面から所定の距離だけ上方に位置するように熱遮蔽部材３６はチャンバ１１内に固定される。また筒部３７の下部には、この筒部３７の内方に膨出しかつ内部に断熱部材４２を有する膨出部４１が設けられる。この筒部３７及び膨出部４１はＣ（黒鉛）により、或いは表面にＳｉＣがコーティングされた黒鉛等により作られる。
【００１６】
図１〜図４に示すように、インゴット２５の外周面と膨出部４１の内周面との間には複数の整流板４３，４４が設けられる。これらの整流板４３，４４は鉛直方向に延びかつインゴット２５の半径方向に平行移動可能にそれぞれ設けられる。具体的には、複数の整流板４３，４４は、インゴット２５の円周方向に所定の間隔をあけて設けられた８枚の長方形板状のインナ整流板４３と、隣合うインナ整流板４３の間に設けられかつ両側縁が隣のインナ整流板４３の側縁に重なる長方形板状の８枚のアウタ整流板４４とを有する（図２及び図３）。上記のようにインナ整流板４３及びアウタ整流板４４を配設することにより、インゴット２５の外径より大きく筒部３７の内径より小さくかつインゴット２５の外周面を包囲する筒状体４６が構成される。
【００１７】
また上記複数の整流板４３，４４の上端は複数の調整板４７，４８の先端にそれぞれ枢着され、これらの調整板４７，４８の基端は膨出部４１にそれぞれ取付けられる（図１〜図４）。具体的には、複数の調整板４７，４８は、基端が膨出部４１の内周面上端に円周方向に所定の間隔をあけて回動可能にそれぞれ取付けられかつ先端に８枚のインナ整流板４３の上端がそれぞれ枢着された８枚の長方形板状のアッパ調整板４７と、隣合うアッパ調整板４７の間に位置し両側縁が隣のアッパ調整板４７の側縁に重なるように基端が膨出部４１の内周面上端に回動可能にそれぞれ取付けられかつ先端に８枚のアウタ整流板４４の上端がそれぞれ枢着された長方形板状の８枚のロア調整板４８とを有する（図２〜図４）。上記のようにアッパ調整板４７及びロア調整板４８を配設することにより、上記筒状体４６と膨出部４１との間の隙間を塞ぐコーン体４９が構成される。
【００１８】
またアッパ調整板４７は、基端が膨出部４１の内周面上端に回動可能に取付けられたアッパ固定部４７ａと、先端にアウタ整流板４４の上端が枢着されかつアッパ固定部４７ａに摺動可能に設けられたアッパ摺動部４７ｂとからなる。アッパ摺動部４７ｂの中央にはインゴット２５の半径方向に延びる長孔４７ｃが形成され、この長孔４７ｃにはアッパ固定部４７ａの先端中央に取付けられた案内軸４７ｄが遊挿される。上記のようにアッパ固定部４７ａにアッパ摺動部４７ｂを連結することにより、アウタ整流板４４を常にインナ整流板４３に接近した状態に保つように、アッパ調整板４７の全長が伸縮可能になっている。なお、図２〜図４の符号４７ｅは案内軸４７ｄからアッパ摺動部４７ｂが離脱するの阻止する平座金である。
【００１９】
更に上記複数の調整板４７，４８は調整板駆動手段５０により駆動・制御される（図１〜図４）。調整板駆動手段５０は、下端がロア調整板４８の先端近傍にそれぞれ取付けられかつ上端がチャンバ１１（図５）外にそれぞれ配索された８本のワイヤ５０ａと、チャンバ１１外に設けられかつ８本のワイヤ５０ａを繰出し可能に巻取るウインチ（図示せず）とを有する。上記ウインチによりワイヤ５０ａを繰出すことにより、複数の調整板４７，４８が図１の破線矢印で示す方向に回転して、複数の整流板４３，４４により構成された筒状体４６がインゴット２５の外周面に近づく方向に平行移動し、ウインチによりワイヤ５０ａを巻取ることにより、複数の調整板４７，４８が一点鎖線矢印で示す方向に回転して、筒状体４６がインゴット２５の外周面から離れる方向に平行移動するように構成される。なお、インナ整流板４３及びアウタ整流板４４の鉛直方向の長さは、筒状体４６をインゴット２５の外周面に近づけたときにこれらの整流板４３，４４の下端がシリコン融液１２の表面に接近して所定の隙間があくように設定される。
【００２０】
なお、インナ整流板４３、アウタ整流板４４、アッパ調整板４７（アッパ固定部４７ａ、アッパ摺動部４７ｂ、ガイドピン４７ｄ及び平座金４７ｅからなる。）、ロア調整板４８及びワイヤ５０ａはＣ（黒鉛）により、或いは表面にＳｉＣがコーティングされた黒鉛等により作られる。また、この実施の形態では、インナ整流板、アウタ整流板、アッパ調整板及びロア調整板の枚数をそれぞれ８枚としたが、７枚以下又は９枚以上であってもよい。また、この実施の形態では、ワイヤをロア調整板の枚数と同一の８本としたが、ロア調整板と同一の本数であれば、７本以下又は９本以上であってもよい。更に、この実施の形態では、ウインチをワイヤの本数と同一の８台としたが、ワイヤと同一の台数であれば、７台以下又は９台以上であってもよく、１台のウインチで全てのワイヤを繰出し可能に巻取ることができれば、１台でもよい。
【００２１】
このように構成された装置を用いてインゴットを引上げる方法を説明する。
先ず、シリコン融液１２を貯留する石英るつぼ１３を所定の回転速度で回転させ、チャンバ１１の上部からチャンバ１１の内部に不活性ガスを供給して、複数の整流板４３，４４により構成された筒状体４６とインゴット２５の間のリング状空間に不活性ガスを流下させつつ、そのシリコン融液１２からインゴット２５を引上げる。このインゴット２５は、このインゴット２５内が格子間シリコン型点欠陥の凝集体及び空孔型点欠陥の凝集体の存在しないパーフェクト領域となる引上げ速度で引上げられる。即ち、インゴット２５は、ＣＺ法によりホットゾーン炉内のシリコン融液１２からボロンコフ（Ｖｏｒｏｎｋｏｖ）の理論に基づいた所定の引上げ速度プロファイルで引上げられる。
【００２２】
一般的に、ＣＺ法によりシリコン融液１２からインゴット２５を引上げると、インゴット２５内には、点欠陥（ｐｏｉｎｔ　ｄｅｆｅｃｔ）と点欠陥の凝集体（ａｇｇｌｏｍｅｒａｔｅｓ：三次元欠陥）が発生する。点欠陥は空孔型点欠陥と格子間シリコン型点欠陥という二つの一般的な形態がある。空孔型点欠陥は一つのシリコン原子がシリコン結晶格子で正常的な位置の一つから離脱したものである。このような空孔が空孔型点欠陥になる。一方、原子がシリコン結晶の格子点以外の位置（インタースチシャルサイト）で発見されるとこれが格子間シリコン点欠陥になる。
【００２３】
点欠陥は一般的にシリコン融液１２とインゴット２５の間の接触面、即ち固液界面２６で形成される。しかし、インゴット２５を連続的に引上げることによって固液界面２６であった部分は引上げとともに冷却し始める。冷却の間、空孔型点欠陥又は格子間シリコン型点欠陥は拡散により互いに合併して、空孔型点欠陥の凝集体（ｖａｃａｎｃｙ　ａｇｇｌｏｍｅｒａｔｅｓ）又は格子間シリコン型点欠陥の凝集体（ｉｎｔｅｒｓｔｉｔｉａｌ　ａｇｇｌｏｍｅｒａｔｅｓ）が形成される。言い換えれば、凝集体は点欠陥の合併に起因して発生する三次元構造となる。
【００２４】
空孔型点欠陥の凝集体は、前述したＣＯＰの他に、ＬＳＴＤ（Ｌａｓｅｒ　Ｓｃａｔｔｅｒｉｎｇ　Ｔｏｍｏｇｒａｐｈ　Ｄｅｆｅｃｔｓ）又はＦＰＤ（Ｆｌｏｗ　Ｐａｔｔｅｒｎ　Ｄｅｆｅｃｔｓ）と呼ばれる欠陥を含み、格子間シリコン型点欠陥の凝集体は前述したＬ／Ｄと呼ばれる欠陥を含む。ＦＰＤとは、インゴット２５をスライスして作製されたシリコンウェーハを３０分間セコエッチング（Ｓｅｃｃｏ　ｅｔｃｈｉｎｇ、ＨＦ：Ｋ_２Ｃｒ_２Ｏ_７（０．１５モル／リットル）＝２：１の混合液によるエッチング）したときに現れる特異なフローパターンを呈する痕跡の源であり、ＬＳＴＤとは、シリコン単結晶内に赤外線を照射したときにシリコンとは異なる屈折率を有し散乱光を発生する源である。
【００２５】
ボロンコフの理論は、欠陥の数が少ない高純度インゴット２５を成長させるために、インゴット２５の引上げ速度をＶ（ｍｍ／分）、インゴット２５とシリコン融液１２の界面２６近傍のインゴット２５中の温度勾配をＧ（℃／ｍｍ）とするときに、Ｖ／Ｇ（ｍｍ^２／分・℃）を制御することである。この理論では、図６に示すように、Ｖ／Ｇを横軸にとり、空孔型点欠陥濃度と格子間シリコン型点欠陥濃度を同一の縦軸にとって、Ｖ／Ｇと点欠陥濃度との関係を図式的に表現し、空孔領域と格子間シリコン領域の境界がＶ／Ｇによって決定されることを説明している。より詳しくは、Ｖ／Ｇ比が臨界点以上では空孔型点欠陥濃度が優勢なインゴット２５が形成される反面、Ｖ／Ｇ比が臨界点以下では格子間シリコン型点欠陥濃度が優勢なインゴット２５が形成される。図６において、［Ｉ］は格子間シリコン型点欠陥が支配的であって、格子間シリコン型点欠陥の凝集体が存在する領域（（Ｖ／Ｇ）_１以下）を示し、［Ｖ］はインゴット２５内での空孔型点欠陥が支配的であって、空孔型点欠陥の凝集体が存在する領域（（Ｖ／Ｇ）_２以上）を示し、［Ｐ］は空孔型点欠陥の凝集体及び格子間シリコン型点欠陥の凝集体が存在しないパーフェクト領域（（Ｖ／Ｇ）_１〜（Ｖ／Ｇ）_２）を示す。領域［Ｐ］に隣接する領域［Ｖ］にはＯＳＦ核を形成する領域［ＯＳＦ］（（Ｖ／Ｇ）_２〜（Ｖ／Ｇ）_３）が存在する。
【００２６】
このパーフェクト領域［Ｐ］は更に領域［Ｐ_Ｉ］と領域［Ｐ_Ｖ］に分類される。［Ｐ_Ｉ］はＶ／Ｇ比が上記（Ｖ／Ｇ）_１から臨界点までの領域であり、［Ｐ_Ｖ］はＶ／Ｇ比が臨界点から上記（Ｖ／Ｇ）_２までの領域である。即ち、［Ｐ_Ｉ］は領域［Ｉ］に隣接し、かつ侵入型転位を形成し得る最低の格子間シリコン型点欠陥濃度未満の格子間シリコン型点欠陥濃度を有する領域であり、［Ｐ_Ｖ］は領域［Ｖ］に隣接し、かつＯＳＦを形成し得る最低の空孔型点欠陥濃度未満の空孔型点欠陥濃度を有する領域である。なお、上記ＯＳＦは、結晶成長時にその核となる微小欠陥が導入され、半導体デバイスを製造する際の熱酸化工程等で顕在化し、作製したデバイスのリーク電流の増加等の不良原因になる。
【００２７】
図１に戻って、シリコン融液１２からインゴット２５を引上げる際には、複数の調整板４７，４８をそれぞれ回動調整して、筒状体４６とインゴット２５との間のリング状空間の横断面積を変化させ、このリング状空間を通過する不活性ガスの流速を変化させることにより、インゴット２５の外周面及びシリコン融液１２の表面の境界部分であるメニスカス１２ａ近傍のシリコン融液１２に発生している対流を変化させる。なお、このメニスカス１２ａ近傍のシリコン融液１２に発生する対流の変化は、予めシミュレーションによるインゴットの引上げや、実験によるインゴットの引上げ等により求めておく。
【００２８】
具体的には、メニスカス１２ａ近傍のシリコン融液１２に図１７に示すような小さくかつ遅い対流１２ｂが発生している場合には、ウインチによりワイヤ５０ａを繰出して調整板４７，４８を図１の破線矢印で示す方向に回転させることにより、筒状体４６をインゴット２５の外周面に近づける方向に平行移動させる。これにより上記リング状空間が狭くなるので、リング状空間を流下する不活性ガスの流速が増大し、メニスカス１２ａの表面に添って流れる不活性ガスの流速も増大する。この結果、上記メニスカス１２ａ近傍のシリコン融液１２に発生していた対流１２ｂは、上記不活性ガスの流速の増大に伴って図１に示すように大きくかつ速くなり、メニスカス１２ａ近傍で下降しかつ固液界面１２ｃの中心近傍で上昇するようになるので、固液界面１２ｃが上凸状になり、固液界面１２ｃの中心近傍の鉛直方向の温度勾配が大きくなる。従って、固液界面１２ｃの中心近傍の鉛直方向の温度勾配と、固液界面１２ｃの周縁近傍の鉛直方向の温度勾配との差が小さくなるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。
【００２９】
一方、メニスカス１２ａから離れたシリコン融液１２の表面近傍に図１８に示すような大きくかつ速い対流１２ｂが発生している場合には、ウインチによりワイヤ５０ａを巻取って調整板４７，４８を図１の一点鎖線矢印で示す方向に回転させることにより、筒状体４６をインゴット２５の外周面から離す方向に平行移動させる。これにより上記リング状空間が広くなるので、リング状空間を流下する不活性ガスの流速が低下し、上記メニスカス１２ａの表面からシリコン融液１２の表面に添って流れる不活性ガスの流速も低下する。この結果、上記メニスカス１２ａから離れたシリコン融液１２の表面近傍に発生していた対流１２ｂは、上記不活性ガスの流速の低下に伴って図１に示す位置まで移動し、メニスカス１２ａ近傍で下降しかつ固液界面１２ｃの中心近傍で上昇するようになるので、固液界面１２ｃが上凸状になり、固液界面１２ｃの中心近傍の鉛直方向の温度勾配が大きくなる。従って、固液界面１２ｃの中心近傍の鉛直方向の温度勾配と、固液界面１２ｃの周縁近傍の鉛直方向の温度勾配との差が小さくなるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。このようにシリコン融液１２の対流１２ｂの変化に応じて筒状体４６をインゴット２５の外周面に近づけたり、或いはインゴット２５の外周面から離すことにより、引上げられるインゴット２５の無欠陥で高品質の部分をその長手方向に拡大できる。
【００３０】
図７〜図１１は本発明の第２の実施の形態を示す。図７〜図１１において図１〜図５と同一符号は同一部品を示す。
この実施の形態では、インゴット２５の外周面と膨出部４１の内周面との間に複数の整流板６４が設けられ、これらの整流板６４の上端が複数の調整板６７，６８の先端にそれぞれ枢着され、更にこれらの調整板６７，６８の基部は膨出部４１の傾斜上面にこの面に沿って移動可能にそれぞれ取付けられる。複数の整流板６４は、第１の実施の形態と同様に、８枚の長方形板状のインナ整流板（図示せず）と、８枚のアウタ整流板６４とを有する（図７）。上記のようにインナ整流板及びアウタ整流板６４を配設することにより、インゴット２５の外径より大きく筒部３７の内径より小さくかつインゴット２５の外周面を包囲する筒状体６６が構成される。
【００３１】
また複数の調整板６７，６８は、基部が膨出部４１の傾斜上面に円周方向に所定の間隔をあけてインゴット２５の半径方向に移動可能にそれぞれ取付けられかつ先端に８枚のアウタ整流板４４の上端がそれぞれ枢着された８枚の略台形板状のロア調整板６８と、隣合うロア調整板６８の間に位置し両側縁が隣のロア調整板６８の側縁に重なるように基部が膨出部４１の傾斜上面にこの面に沿って移動可能にそれぞれ取付けられかつ先端に８枚のインナ整流板の上端がそれぞれ枢着された略台形板状の８枚のアッパ調整板６７とを有する（図７〜図１１）。上記のようにロア調整板６８及びアッパ調整板６７を配設することにより、上記複数の整流板６４により構成された筒状体６６と膨出部４１との間の隙間を塞ぐコーン体６９が構成される。
【００３２】
ロア調整板６８の中央にはインゴット２５の半径方向に延びる長孔６８ａが形成され、この長孔６８ａには膨出部４１の傾斜上面に取付けられたガイドピン６８ｂが遊挿される。また膨出部４１の傾斜上面には、傾斜上面から一部が突出してロア調整板６８を受ける転動ローラ６８ｃが回転可能に埋設される。これによりロア調整板６８はガイドピン６８ｂに案内されて転動ローラ６８ｃ上をインゴット２５の半径方向に往復動可能に構成される。
【００３３】
更に上記複数の調整板６７，６８は調整板駆動手段７０により駆動・制御される（図７及び図１１）。調整板駆動手段７０は、下端がロア調整板６８及びアッパ調整板６７の基端にそれぞれ取付けられかつ上端がチャンバ外にそれぞれ配索された１６本のワイヤ７０ａと、チャンバ外に設けられ１６本のワイヤ７０ａを繰出し可能に巻取るウインチ（図示せず）とを有する。図７及び図１１の符号７０ｂはワイヤ７０ａを膨出部４１の傾斜上面から筒部３７内面に沿うように案内するガイドローラである。なお、インナ整流板及びアウタ整流板６４の鉛直方向の長さは、筒状体６６をインゴット２５の外周面に近づけたときにこれらの整流板６４の下端がシリコン融液１２の表面に接近して所定の隙間があくように設定される。上記以外は第１の実施の形態と同一に構成される。
【００３４】
このように構成された装置を用いてインゴットを引上げる方法を説明する。
メニスカス１２ａ近傍のシリコン融液１２に図１７に示すような小さくかつ遅い対流１２ｂが発生している場合には、ウインチによりワイヤ７０ａを繰出すと、調整板６７，６８が膨出部４１の傾斜上面を図７の破線矢印で示す方向、即ち傾斜上面を下る方向に移動するため、筒状体６６がインゴット２５の外周面に近づく方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。
【００３５】
一方、メニスカス１２ａから離れたシリコン融液１２の表面近傍に図１８に示すような大きくかつ速い対流１２ｂが発生している場合には、ウインチによりワイヤ７０ａを巻取ると、調整板６７，６８が膨出部４１の傾斜上面を図７の一点鎖線矢印で示す方向、即ち傾斜上面を上る方向に移動するため、筒状体６６がインゴット２５の外周面から離れる方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。このようにシリコン融液１２の対流１２ｂの変化に応じて筒状体６６をインゴット２５の外周面に近づけたり、或いはインゴット２５の外周面から離すことにより、引上げられるインゴット２５の無欠陥で高品質の部分をその長手方向に拡大できる。なお、この実施の形態では、複数の調整板６７，６８が膨出部４１の上面に常に沿った状態に保たれるので、インゴット２５及び筒部３７間を流下した不活性ガスを第１の実施の形態より速やかにインゴット２５及び筒状体４６間に導くことができる。
【００３６】
図１２〜図１４は本発明の第３の実施の形態を示す。図１２〜図１４において図１〜図５と同一符号は同一部品を示す。
この実施の形態では、インゴット２５の外周面と膨出部４１の内周面との間に複数の整流板７４が設けられ、これらの整流板７４の上端が複数の調整板７７，７８の先端にそれぞれ枢着され、更にこれらの調整板７７，７８の基部は膨出部４１の傾斜下面にこの面に沿って移動可能にそれぞれ取付けられる。複数の整流板７４は、第１の実施の形態と同様に、８枚の長方形板状のインナ整流板（図示せず）と、８枚のアウタ整流板７４とを有する（図１２）。上記のようにインナ整流板及びアウタ整流板７４を配設することにより、インゴット２５の外径より大きく筒部３７の内径より小さくかつインゴット２５の外周面を包囲する筒状７６体が構成される。なお、この筒状体７６は、インゴット２５の外周面と膨出部４１の内周面下方への延長面との間に設けられる。
【００３７】
また複数の調整板７７，７８は、基部が膨出部４１の傾斜下面に円周方向に所定の間隔をあけてインゴット２５の半径方向に移動可能にそれぞれ取付けられかつ先端に８枚のアウタ整流板７４の上端がそれぞれ枢着された８枚の略台形板状のロア調整板７８と、隣合うロア調整板７８の間に位置し両側縁が隣のロア調整板７８の側縁に重なるように基部が膨出部４１の傾斜下面にこの面に沿って移動可能にそれぞれ取付けられかつ先端に８枚のインナ整流板の上端がそれぞれ枢着された略台形板状の８枚のアッパ調整板７７とを有する（図１２〜図１４）。上記のようにロア調整板７８及びアッパ調整板７７を配設することにより、上記複数の整流板７４により構成された筒状体７６と膨出部４１との間の隙間を塞ぐコーン体７９が構成される。
【００３８】
ロア調整板７８の中央にはインゴット２５の半径方向に延びる長孔７８ａが形成され、この長孔７８ａには膨出部４１の傾斜下面に取付けられたガイドピン７８ｂが遊挿される。またガイドピン７８ｂの下端には、ロア調整板７８を受ける転動ローラ７８ｃが回転可能に取付けられる。これによりロア調整板７８はガイドピン７８ｂに案内されて転動ローラ７８ｃ上をインゴット２５の半径方向に往復動可能に構成される。
【００３９】
更に上記複数の調整板７７，７８は調整板駆動手段７０により駆動・制御される（図１２及び図１４）。調整板駆動手段７０は、下端がロア調整板７８及びアッパ調整板７７の基端にそれぞれ取付けられかつ上端がチャンバ外にそれぞれ配索された１６本のワイヤ７０ａと、チャンバ外に設けられ１６本のワイヤ７０ａを繰出し可能に巻取るウインチ（図示せず）とを有する。図１２及び図１４の符号７０ｂはワイヤ７０ａを膨出部４１の傾斜下面から膨出部４１外面を通って筒部３７外面に沿うように案内するガイドローラである。なお、インナ整流板及びアウタ整流板７４の鉛直方向の長さは、筒状体７６をインゴット２５の外周面に近づけたときにこれらの整流板７４の下端がシリコン融液１２の表面に接近して所定の隙間があくように設定される。上記以外は第１の実施の形態と同一に構成される。
【００４０】
このように構成された装置を用いてインゴットを引上げる方法を説明する。
メニスカス１２ａ近傍のシリコン融液１２に図１７に示すような小さくかつ遅い対流１２ｂが発生している場合には、ウインチによりワイヤ７０ａを繰出すと、調整板７７，７８が膨出部４１の傾斜下面を図１２の破線矢印で示す方向、即ちに傾斜下面を下る方向に移動することにより、筒状体７６がインゴット２５の外周面に近づく方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。
【００４１】
一方、メニスカス１２ａから離れたシリコン融液１２の表面近傍に図１８に示すような大きくかつ速い対流１２ｂが発生している場合には、ウインチによりワイヤ７０ａを巻取ると、調整板７７，７８が膨出部４１の傾斜下面を図１２の一点鎖線矢印で示す方向、即ち傾斜下面を上る方向に移動することにより、筒状体７６がインゴット２５の外周面から離れる方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。このようにシリコン融液１２の対流１２ｂの変化に応じて筒状体７６をインゴット２５の外周面に近づけたり、或いはインゴット２５の外周面から離すことにより、引上げられるインゴット２５の無欠陥で高品質の部分をその長手方向に拡大できる。なお、この実施の形態では、複数の調整板７７，７８が膨出部４１の下面に常に沿った状態に保たれるので、膨出部４１に対向するインゴット２５外周面に沿う不活性ガスの流速を変化させずに、メニスカス１２ａ近傍における不活性ガスの流速のみを変化させることができ、チャンバ１１内全体にわたって不活性ガスを高流速化することによりインゴット２５が揺動するのを未然に防止できるという効果が得られる。
【００４２】
図１５は本発明の第４の実施の形態を示す。図１５において図７と同一符号は同一部品を示す。
この実施の形態では、膨出部８１の上面が水平に形成され、複数の調整板６７，６８がこの水平な膨出部８１の上面をインゴット２５の半径方向に移動可能に構成され、更にこれらの調整板６７，６８は調整板駆動手段８０により駆動・制御される。調整板駆動手段８０は、一端がロア調整板６８及びアッパ調整板６７の基端にそれぞれ取付けられかつ他端がチャンバ外にそれぞれ配索された１６本の第１ワイヤ８０ａと、一端がロア調整板６８及びアッパ調整板６７の中央下面にそれぞれ取付けられかつ他端がチャンバ外にそれぞれ配索された１６本の第２ワイヤ８０ｂと、チャンバ外に設けられ上記第１及び第２ワイヤ８０ａ，８０ｂを繰出し可能に巻取るウインチ（図示せず）とを有する。図１５の符号８０ｃは第１ワイヤ８０ａや第２ワイヤ８０ｂを膨出部８１や筒部３７に沿うように案内するガイドローラである。上記以外は第２の実施の形態と同一に構成される。
【００４３】
このように構成された装置を用いてインゴットを引上げる方法を説明する。
メニスカス１２ａ近傍のシリコン融液１２に図１７に示すような小さくかつ遅い対流１２ｂが発生している場合には、ウインチにより第１ワイヤ８０ａを繰出しかつ第２ワイヤ８０ｂを巻取ると、調整板６７，６８が膨出部８１の上面を破線矢印で示す方向に移動するため、筒状体６６がインゴット２５の外周面に近づく方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。
【００４４】
一方、メニスカス１２ａから離れたシリコン融液１２の表面近傍に図１８に示すような大きくかつ速い対流１２ｂが発生している場合には、ウインチにより第１ワイヤ８０ａを巻取りかつ第２ワイヤ８０ｂを繰出すと、調整板６７，６８が膨出部８１の上面を一点鎖線矢印で示す方向に移動するため、筒状体６６がインゴット２５の外周面から離れる方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。このようにシリコン融液１２の対流１２ｂの変化に応じて筒状体６６をインゴット２５の外周面に近づけたり、或いはインゴット２５の外周面から離すことにより、引上げられるインゴット２５の無欠陥で高品質の部分をその長手方向に拡大できる。なお、この実施の形態の第１及び第２ワイヤ８０ａ，８０ｂを有する調整板駆動手段８０は、膨出部の上面が水平でなく、膨出部の上面がインゴット２５の外周面に向うに従って緩やかな角度で傾斜している場合、即ちウインチによりワイヤを繰出しても調整板がその自重により膨出部の上面を下る方向に移動しない場合にも適用できる。
【００４５】
図１６は本発明の第５の実施の形態を示す。図１６において図１２と同一符号は同一部品を示す。
この実施の形態では、膨出部８１の下面が水平に形成され、調整板７７，７８がこの水平な膨出部８１の下面をインゴット２５の半径方向に移動可能に構成され、更にこれらの調整板７７，７８は調整板駆動手段８０により駆動・制御される。調整板駆動手段８０は、一端がロア調整板７８及びアッパ調整板７７の基端にそれぞれ取付けられかつ他端がチャンバ外にそれぞれ配索された１６本の第１ワイヤ８０ａと、一端がロア調整板７８及びアッパ調整板７７の中央上面にそれぞれ取付けられかつ他端がチャンバ外にそれぞれ配索された１６本の第２ワイヤ８０ｂと、チャンバ外に設けられ上記第１及び第２ワイヤ８０ａ，８０ｂを繰出し可能に巻取るウインチ（図示せず）とを有する。図１６の符号８０ｃは第１ワイヤ８０ａや第２ワイヤ８０ｂを膨出部８１や筒部３７に沿うように案内するガイドローラである。上記以外は第３の実施の形態と同一に構成される。
【００４６】
このように構成された装置を用いてインゴットを引上げる方法を説明する。
メニスカス１２ａ近傍のシリコン融液１２に図１７に示すような小さくかつ遅い対流１２ｂが発生している場合には、ウインチにより第１ワイヤ８０ａを繰出しかつ第２ワイヤ８０ｂを巻取ると、調整板７７，７８が膨出部８１の下面を破線矢印で示す方向に移動するため、筒状体７６がインゴット２５の外周面に近づく方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。
【００４７】
一方、メニスカス１２ａから離れたシリコン融液１２の表面近傍に図１８に示すような大きくかつ速い対流１２ｂが発生している場合には、ウインチにより第１ワイヤ８０ａを巻取りかつ第２ワイヤ８０ｂを繰出すと、調整板７７，７８が膨出部８１の下面を一点鎖線矢印で示す方向に移動するため、筒状体７６がインゴット２５の外周面から離れる方向に平行移動する。これにより第１の実施の形態と同様に、固液界面１２ｃが上凸状になるので、引上げられるインゴット２５はその径方向及びその長手方向にわたって無欠陥で高品質となる。このようにシリコン融液１２の対流１２ｂの変化に応じて筒状体７６をインゴット２５の外周面に近づけたり、或いはインゴット２５の外周面から離すことにより、引上げられるインゴット２５の無欠陥で高品質の部分をその長手方向に拡大できる。なお、この実施の形態の第１及び第２ワイヤ８０ａ，８０ｂを有する調整板駆動手段８０は、膨出部８１の下面が水平でなく、膨出部の下面がインゴットの外周面に向うに従って緩やかな角度で傾斜している場合、即ちウインチによりワイヤを繰出しても調整板がその自重により膨出部の下面を下る方向に移動しない場合にも適用できる。
【００４８】
【発明の効果】
以上述べたように、本発明によれば、インゴットの外周面と膨出部の内周面又はこの内周面の延長面との間に鉛直方向に延びかつインゴットの半径方向に移動可能に設けられた複数の整流板がインゴットの外周面を包囲し、基端又は基部を膨出部に取付けかつ先端に複数の整流板の上端を枢着した複数の調整板が複数の整流板及び膨出部間の隙間を塞ぎ、更にシリコン融液の対流の変化に応じて調整板駆動手段が複数の調整板を駆動・制御するように構成したので、メニスカス近傍のシリコン融液に所定の対流が発生しているときに、複数の整流板をインゴットの外周面に近づけると、複数の整流板及びインゴット間を流下する不活性ガスの流速が増大する。この結果、メニスカスの表面を流下する不活性ガスの流速が増大するので、シリコン融液には、メニスカス近傍で下降しかつシリコン融液及びインゴット間の固液界面の中心近傍で上昇する比較的大きな対流が発生し、固液界面が上凸状になる。従って、固液界面の中心近傍の鉛直方向の温度勾配と、固液界面の周縁近傍の鉛直方向の温度勾配との差が小さくなるので、引上げられるインゴットの無欠陥で高品質の部分をその長手方向に拡大できる。
【図面の簡単な説明】
【図１】本発明第１実施形態の引上げ装置を示す図５のＡ部拡大断面図。
【図２】図４のＢ−Ｂ線断面図。
【図３】図４のＣ−Ｃ線断面図。
【図４】図１のＤ−Ｄ線断面図。
【図５】その引上げ装置の縦断面構成図。
【図６】ボロンコフの理論に基づいた、Ｖ／Ｇ比が臨界点以上で空孔型点欠陥濃度が優勢なインゴットが形成され、Ｖ／Ｇ比が臨界点以下で格子間シリコン型点欠陥濃度が優勢なインゴットが形成されることを示す図。
【図７】本発明の第２実施形態を示す図１に対応する断面図。
【図８】図７のＥ−Ｅ線断面図。
【図９】図８のＦ−Ｆ線断面図。
【図１０】図８のＧ−Ｇ線断面図。
【図１１】図７のＨ−Ｈ線断面図。
【図１２】本発明の第３実施形態を示す図１に対応する断面図。
【図１３】図１２のＩ−Ｉ線断面図。
【図１４】図１３のＪ−Ｊ線断面図。
【図１５】本発明の第４実施形態を示す図７に対応する断面図。
【図１６】本発明の第５実施形態を示す図１２に対応する断面図。
【図１７】従来のメニスカス近傍のシリコン融液に小さくかつ遅い対流が発生した状態を示す図１に対応する断面図。
【図１８】従来のメニスカスから離れたシリコン融液の表面近傍に大きくかつ速い対流が発生した状態を示す図１に対応する断面図。
【符号の説明】
１１　チャンバ
１２　シリコン融液
１２ｂ　対流
１３　石英るつぼ
２５　インゴット
２８　ガス給排手段
３６　熱遮蔽部材
３７　筒部
４１，８１　膨出部
４３，４４，６４，７４　整流板
４７，４８，６７，６８，７７，７８　調整板
５０，７０，８０　調整板駆動手段
５０ａ，７０ａ，８０ａ，８０ｂ　ワイヤ[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for controlling the flow rate of an inert gas when pulling a silicon single crystal ingot (hereinafter simply referred to as an ingot) from a silicon melt stored in a quartz crucible.
[0002]
[Prior art]
Conventionally, as a method for manufacturing a silicon single crystal, a method of pulling an ingot by a Czochralski method (hereinafter, referred to as a CZ method) is known. The CZ method is a method of manufacturing a cylindrical ingot by bringing a seed crystal into contact with a silicon melt stored in a quartz crucible and pulling the seed crystal while rotating the quartz crucible and the seed crystal.
[0003]
On the other hand, in a process of manufacturing a semiconductor integrated circuit, as a cause of lowering the yield, a micro defect of an oxygen precipitate serving as a nucleus of an oxidation-induced stacking fault (hereinafter, referred to as OSF) or a crystal is a cause. The presence of particles (Crystal Originated Particles, hereinafter referred to as COP) or interstitial-type large dislocations (hereinafter, referred to as L / D) is cited. OSF introduces microscopic defects serving as nuclei during crystal growth, becomes apparent in a thermal oxidation step or the like when manufacturing a semiconductor device, and causes defects such as an increase in leak current of the manufactured device. COPs are pits caused by crystals that appear on the wafer surface when the mirror-polished silicon wafer is washed with a mixed solution of ammonia and hydrogen peroxide. When this wafer is measured by a particle counter, the pits are also detected as light scattering defects together with the original particles.
[0004]
This COP causes deterioration of electrical characteristics such as a time-dependent dielectric breakdown characteristic (Time Dependent Breakdown, TDDB) of the oxide film and a dielectric breakdown voltage characteristic (Time Zero Dielectric Breakdown, TZDB) of the oxide film. Also, if COP exists on the wafer surface, a step is generated in a device wiring process, which may cause disconnection. This also causes a leak or the like in the element isolation portion, and lowers the product yield. Further, L / D is also called a dislocation cluster because a pit is generated when a silicon wafer having this defect is immersed in a selective etching solution containing hydrofluoric acid as a main component. This L / D also causes deterioration of electrical characteristics such as leak characteristics and isolation characteristics. As a result, it is necessary to reduce OSF, COP and L / D from a silicon wafer used for manufacturing a semiconductor integrated circuit.
[0005]
A method of manufacturing a silicon single crystal ingot for cutting out a defect-free silicon wafer having no OSF, COP and L / D is disclosed (for example, see Patent Document 1). In general, when the ingot is pulled up at a high speed, a region [V] in which agglomerates of vacancy type point defects are predominantly formed is formed inside the ingot. A region [I] where an aggregate of silicon type point defects predominantly exists is formed. For this reason, in the above-mentioned manufacturing method, by pulling the ingot at an optimum pulling speed, it is possible to manufacture a silicon single crystal composed of a perfect region [P] in which the above-mentioned point defect aggregate does not exist.
[0006]
[Patent Document 1]
JP-A-11-1393 corresponding to U.S. Pat. No. 6,045,610.
[0007]
[Problems to be solved by the invention]
However, in the conventional method for manufacturing a silicon single crystal ingot disclosed in Patent Document 1, it is necessary to control the temperature gradient in the vertical direction near the solid-liquid interface between the ingot and the silicon melt to be uniform. Since this control is affected by a change in the remaining amount of silicon melt and a change in convection, it is difficult to enlarge a defect-free and high-quality portion in the longitudinal direction of the straight body portion of the ingot.
SUMMARY OF THE INVENTION An object of the present invention is to provide an inert gas flow rate control device and a flow rate control method thereof for a silicon single crystal pulling apparatus, which can expand a defect-free and high quality portion of a pulled ingot in its longitudinal direction.
[0008]
[Means for Solving the Problems]
As shown in FIGS. 1 and 5, the invention according to claim 1 includes a quartz crucible 13 provided in a chamber 11 and storing a silicon melt 12, and a silicon crucible 13 surrounding an outer peripheral surface of the quartz crucible 13. A heater 18 for heating the ingot 25 pulled up from the silicon melt 12, a cylindrical portion 37 surrounding the outer peripheral surface of the ingot 25 and having a lower end located above the silicon melt 12 at an interval from the surface thereof, and a lower inner portion of the cylindrical portion 37. A heat shielding member 36 having a bulging portion 41 bulging out of the chamber 11, and supplying an inert gas from the upper portion of the chamber 11 to the inside of the chamber 11 so as to provide an inert gas between the bulging portion 41 and the ingot 25. This is an improvement of the silicon single crystal pulling apparatus provided with the inert gas supply / discharge means 28 for causing the gas to flow down.
[0009]
The characteristic configuration is provided between the outer peripheral surface of the ingot 25 and the inner peripheral surface of the bulging portion 41 or an extension surface of the inner peripheral surface in the vertical direction and is provided so as to be able to move in parallel in the radial direction of the ingot 25. Further, a plurality of rectifying plates 43 and 44 surrounding the outer peripheral surface of the ingot 25 and a plurality of rectifying plates 43 and 44 each having a base end or a base attached to the bulging portion 41 and an upper end pivotally attached to the distal end, respectively. A plurality of adjusting plates 47 and 48 for closing a gap between the rectifying plates 43 and 44 and the bulging portion 41, and a plurality of rectifying plates 43 and 44 in accordance with a change in the convection 12b of the silicon melt 12 and an outer peripheral surface of the ingot 25. The solid-liquid interface 12c between the ingot 25 and the silicon melt 12 becomes upwardly convex by driving each of the plurality of adjusting plates 47 and 48 so as to approach or separate from the outer peripheral surface of the ingot 25. There is to provided with an adjusting plate driving means 50 for controlling the.
[0010]
As shown in FIGS. 1 and 5, the invention according to claim 4 rotates the quartz crucible 13 storing the silicon melt 12 at a predetermined rotation speed, surrounds the ingot 25 pulled up from the silicon melt 12, and A heat shielding member 36 having a cylindrical portion 37 whose lower end is located above the surface of the silicon melt 12 at an interval from the surface of the silicon melt 12 and a bulging portion 41 bulging inward at a lower portion of the cylindrical portion 37 is provided. An inert gas is supplied from the upper part of the chamber 11 into the inside of the chamber 11 so that the inert gas flows between the bulging portion 41 and the ingot 25, and the inside of the ingot 25 has aggregates of interstitial silicon type point defects and a void type. This is an improvement in a silicon single crystal pulling method in which the ingot 25 is pulled at a pulling speed at which a perfect region free of point defect aggregates is present.
The characteristic configuration is provided between the outer peripheral surface of the ingot 25 and the inner peripheral surface of the bulging portion 41 or an extension surface of the inner peripheral surface in the vertical direction and is provided so as to be able to move in parallel in the radial direction of the ingot 25. A plurality of rectifying plates 43, 44 surround the outer peripheral surface of the ingot 25, and a plurality of adjustments in which a base end or a base is attached to the bulging portion 41 and upper ends of the plurality of rectifying plates 43, 44 are pivotally attached to the distal ends, respectively. The plates 47 and 48 close the gap between the plurality of rectifying plates 43 and 44 and the bulging portion 41, and approach the outer peripheral surface of the ingot 25 or from the outer peripheral surface of the ingot 25 according to the change of the convection 12b of the silicon melt 12. When the adjusting plate driving means 50 drives the plurality of adjusting plates 47 and 48 respectively so as to separate them, the solid-liquid interface 12c between the ingot 25 and the silicon melt 12 is controlled to be convex. Located in.
[0011]
In the inert gas flow rate control device described in the first aspect or the inert gas flow rate control method described in the fourth aspect, the meniscus which is a boundary portion between the outer peripheral surface of the ingot 25 and the surface of the silicon melt 12 is provided. When a predetermined convection 12b is generated in the silicon melt 12 near 12a, the plurality of adjusting plates 47, 48 are driven by the adjusting plate driving means 50 to move the plurality of rectifying plates 43, 44 to the outer periphery of the ingot 25. As the surface approaches the surface, the flow rate of the inert gas flowing between the plurality of current plates 43 and 44 and the ingot 25 increases. As a result, the flow rate of the inert gas flowing down the surface of the meniscus 12a increases, so that the silicon melt 12 descends near the meniscus 12a and near the center of the solid-liquid interface 12c between the silicon melt 12 and the ingot 25. A relatively large convection 12b that rises is generated, and the solid-liquid interface 12c becomes upwardly convex, so that the temperature gradient in the vertical direction near the center of the solid-liquid interface 12c increases. As a result, the difference between the temperature gradient in the vertical direction near the center of the solid-liquid interface 12c and the temperature gradient in the vertical direction near the periphery of the solid-liquid interface 12c is reduced. The part can be enlarged in its longitudinal direction.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a first embodiment of the present invention will be described with reference to the drawings.
FIG. 5 shows a silicon single crystal pulling apparatus 10 of the present invention. A quartz crucible 13 for storing a silicon melt 12 is provided in a chamber 11 of the pulling apparatus 10, and the outer peripheral surface of the quartz crucible 13 is covered with a graphite susceptor 14. The lower surface of the quartz crucible 13 is fixed to the upper end of a support shaft 16 via the graphite susceptor 14, and the lower portion of the support shaft 16 is connected to a crucible driving unit 17. The crucible driving means 17 includes a first rotation motor (not shown) for rotating the quartz crucible 13 and a lifting / lowering motor for moving the quartz crucible 13 up and down, and these motors can rotate the quartz crucible 13 in a predetermined direction. At the same time, it can be moved up and down. The outer peripheral surface of the quartz crucible 13 is surrounded by a heater 18 at a predetermined interval from the quartz crucible 13, and the heater 18 is surrounded by a heat retaining tube 19. The heater 18 heats and melts the high-purity polycrystalline silicon charged into the quartz crucible 13 to form the silicon melt 12.
[0013]
A cylindrical casing 21 is connected to the upper end of the chamber 11. The casing 21 is provided with a pulling means 22. The pulling means 22 includes a pulling head (not shown) rotatably provided at the upper end of the casing 21 in a horizontal state, a second rotation motor (not shown) for rotating the head, and a quartz crucible 13 from the head. And a pull-up motor (not shown) provided in the head for winding up or feeding out the wire cable 23. At the lower end of the wire cable 23 is attached a seed crystal 24 for dipping in the silicon melt 12 and pulling up the ingot 25.
Further, a gas supply / discharge means 28 for supplying an inert gas to the ingot side of the chamber 11 and discharging the inert gas from the inner peripheral side of the crucible of the chamber 11 is connected to the chamber 11. The gas supply / discharge means 28 has one end connected to the peripheral wall of the casing 21 and the other end connected to a supply pipe 29 connected to a tank (not shown) for storing the inert gas, and one end connected to the lower wall of the chamber 11. The other end has a discharge pipe 30 connected to a vacuum pump (not shown). The supply pipe 29 and the discharge pipe 30 are respectively provided with first and second flow control valves 31 and 32 for controlling the flow rate of the inert gas flowing through these pipes 29 and 30.
[0014]
On the other hand, an encoder (not shown) is provided on an output shaft (not shown) of the pulling motor, and an encoder (not shown) for detecting the vertical position of the support shaft 16 is provided on the crucible driving means 17. Each detection output of the two encoders is connected to a control input of a controller (not shown), and the control output of the controller is connected to a pulling motor of the pulling means 22 and a lifting motor of the crucible driving means, respectively. The controller is provided with a memory (not shown), in which the winding length of the wire cable 23 relative to the detection output of the encoder, that is, the pulling length of the ingot 25 is stored as a first map. Further, the liquid level of the silicon melt 12 in the quartz crucible 13 with respect to the pulling length of the ingot 25 is stored in the memory as a second map. The controller is configured to control the elevating motor of the crucible driving means 17 so as to always keep the liquid level of the silicon melt 12 in the quartz crucible 13 at a constant level based on the detection output of the encoder in the pulling motor. Is done.
[0015]
A heat shielding member 36 surrounding the outer peripheral surface of the ingot 25 is provided between the outer peripheral surface of the ingot 25 and the inner peripheral surface of the quartz crucible 13. The heat shielding member 36 has a cylindrical portion 37 which is formed in a cylindrical shape and blocks radiant heat from the heater 18, and a flange portion 38 which is connected to an upper edge of the cylindrical portion 37 and projects outward in a substantially horizontal direction. The heat shielding member 36 is fixed in the chamber 11 by placing the flange portion 38 on the heat retaining cylinder 19 such that the lower edge of the cylindrical portion 37 is located a predetermined distance above the surface of the silicon melt 12. You. A bulging portion 41 bulging inward of the cylindrical portion 37 and having a heat insulating member 42 therein is provided below the cylindrical portion 37. The cylindrical portion 37 and the bulging portion 41 are made of C (graphite), graphite whose surface is coated with SiC, or the like.
[0016]
As shown in FIGS. 1 to 4, a plurality of rectifying plates 43 and 44 are provided between the outer peripheral surface of the ingot 25 and the inner peripheral surface of the bulging portion 41. These current plates 43 and 44 extend in the vertical direction and are provided so as to be able to move in parallel in the radial direction of the ingot 25. Specifically, the plurality of rectifying plates 43 and 44 are formed of eight rectangular plate-shaped inner rectifying plates 43 provided at predetermined intervals in the circumferential direction of the ingot 25 and the adjacent inner rectifying plates 43. It has eight rectangular plate-shaped outer rectifying plates 44 provided between them and both side edges of which overlap the side edges of the adjacent inner rectifying plate 43 (FIGS. 2 and 3). By disposing the inner rectifying plate 43 and the outer rectifying plate 44 as described above, a cylindrical body 46 that is larger than the outer diameter of the ingot 25 and smaller than the inner diameter of the cylindrical portion 37 and surrounds the outer peripheral surface of the ingot 25 is configured. You.
[0017]
In addition, the upper ends of the plurality of rectifying plates 43 and 44 are pivotally attached to the tips of the plurality of adjusting plates 47 and 48, respectively, and the base ends of the adjusting plates 47 and 48 are respectively attached to the bulging portions 41 (FIGS. 1 to 1). (Fig. 4). Specifically, the plurality of adjusting plates 47 and 48 are rotatably mounted at their base ends at the upper end of the inner peripheral surface of the bulging portion 41 at predetermined intervals in the circumferential direction, and have eight base plates at their front ends. Eight rectangular plate-shaped upper adjustment plates 47 each having the upper end of the inner rectifying plate 43 pivotally attached thereto, and both side edges are located between the adjacent upper adjustment plates 47 and overlap the side edges of the adjacent upper adjustment plates 47. The base end is rotatably attached to the upper end of the inner peripheral surface of the bulging portion 41, and the upper ends of the eight outer rectifying plates 44 are pivotally attached to the ends, respectively, so as to form eight lower adjustment plates in the form of rectangular plates. 48 (FIGS. 2 to 4). By disposing the upper adjustment plate 47 and the lower adjustment plate 48 as described above, a cone body 49 that closes the gap between the tubular body 46 and the bulging portion 41 is configured.
[0018]
The upper adjustment plate 47 has an upper fixing portion 47a whose base end is rotatably attached to the upper end of the inner peripheral surface of the bulging portion 41, and an upper end of the outer rectifying plate 44 which is pivotally attached to the distal end thereof. And an upper sliding portion 47b slidably provided on the upper surface. A long hole 47c extending in the radial direction of the ingot 25 is formed at the center of the upper sliding portion 47b, and a guide shaft 47d attached to the center of the tip of the upper fixing portion 47a is loosely inserted into the long hole 47c. By connecting the upper sliding portion 47b to the upper fixing portion 47a as described above, the entire length of the upper adjusting plate 47 can be extended and contracted so that the outer rectifying plate 44 is always kept close to the inner rectifying plate 43. ing. Reference numeral 47e in FIGS. 2 to 4 denotes a flat washer for preventing the upper sliding portion 47b from coming off the guide shaft 47d.
[0019]
Further, the plurality of adjusting plates 47 and 48 are driven and controlled by adjusting plate driving means 50 (FIGS. 1 to 4). The adjusting plate driving means 50 is provided outside the chamber 11 with eight wires 50a each having a lower end attached near the distal end of the lower adjusting plate 48 and an upper end respectively routed outside the chamber 11 (FIG. 5). A winch (not shown) that winds up the eight wires 50a so as to be able to be fed out. By pulling out the wire 50a by the winch, the plurality of adjusting plates 47 and 48 rotate in the direction shown by the dashed arrows in FIG. 1, and the cylindrical body 46 constituted by the plurality of rectifying plates 43 and 44 becomes ingot 25. The parallel movement in the direction approaching the outer peripheral surface of the ingot 25 and the winding of the wire 50a by the winch causes the plurality of adjusting plates 47, 48 to rotate in the direction indicated by the dashed-dotted arrow, and the cylindrical body 46 to move to the outer peripheral surface of the ingot 25. It is configured to translate in a direction away from the object. Note that the vertical lengths of the inner rectifying plate 43 and the outer rectifying plate 44 are such that the lower ends of the rectifying plates 43 and 44 face the surface of the silicon melt 12 when the cylindrical body 46 is brought close to the outer peripheral surface of the ingot 25. Is set so that a predetermined gap is created in the vicinity of.
[0020]
The inner rectifying plate 43, the outer rectifying plate 44, the upper adjusting plate 47 (comprising the upper fixing portion 47a, the upper sliding portion 47b, the guide pin 47d and the flat washer 47e), the lower adjusting plate 48 and the wire 50a are C ( (Graphite) or graphite coated with SiC on the surface. Further, in this embodiment, the number of the inner rectifying plate, the outer rectifying plate, the upper adjusting plate, and the lower adjusting plate is eight, respectively, but may be seven or less or nine or more. Further, in this embodiment, the number of wires is eight, which is the same as the number of lower adjustment plates. However, if the number of wires is the same as that of the lower adjustment plates, the number may be seven or less or nine or more. Furthermore, in this embodiment, the number of winches is eight, which is the same as the number of wires. However, as long as the number is the same as the number of wires, the number may be seven or less, or nine or more. May be used as long as the wire can be wound up so as to be able to be fed out.
[0021]
A method for pulling up an ingot using the device configured as described above will be described.
First, the quartz crucible 13 storing the silicon melt 12 was rotated at a predetermined rotation speed, and an inert gas was supplied from above the chamber 11 into the inside of the chamber 11. The ingot 25 is pulled up from the silicon melt 12 while flowing the inert gas into the ring-shaped space between the cylindrical body 46 and the ingot 25. The ingot 25 is pulled up at a pulling speed at which the inside of the ingot 25 becomes a perfect region where there are no aggregates of interstitial silicon type point defects and aggregates of vacancy type point defects. That is, the ingot 25 is pulled up by the CZ method from the silicon melt 12 in the hot zone furnace with a predetermined pulling speed profile based on Voronkov's theory.
[0022]
Generally, when the ingot 25 is pulled from the silicon melt 12 by the CZ method, point defects and agglomerates (three-dimensional defects) of the point defects are generated in the ingot 25. Point defects have two general forms: vacancy type point defects and interstitial silicon type point defects. A vacancy-type point defect is one in which one silicon atom has separated from one of the normal positions in the silicon crystal lattice. Such holes become hole type point defects. On the other hand, if an atom is found at a position (interstitial site) other than the lattice point of the silicon crystal, this becomes an interstitial silicon point defect.
[0023]
Point defects are generally formed at the contact surface between the silicon melt 12 and the ingot 25, that is, at the solid-liquid interface 26. However, by continuously pulling up the ingot 25, the portion that was the solid-liquid interface 26 starts to cool down with the pulling up. During cooling, the vacancy-type point defects or interstitial silicon-type point defects merge with each other by diffusion to form vacancy agglomerates or interstitial silicon-type defect agglomerates. Is formed. In other words, the aggregate has a three-dimensional structure generated due to the merging of point defects.
[0024]
Aggregates of vacancy-type point defects include defects called LSTDs (Laser Scattering Tomograph Defects) or FPDs (Flow Pattern Defects), in addition to the above-mentioned COPs. / D. FPD means that a silicon wafer manufactured by slicing an ingot 25 is secco-etched for 30 minutes (Secco etching, HF: K ₂ Cr ₂ O ₇ (0.15 mol / liter) = a source of a trace exhibiting a unique flow pattern that appears when etching is performed using a mixed solution of 2: 1. Is a source having a different refractive index from that of scattered light.
[0025]
Boronkov's theory states that, in order to grow a high-purity ingot 25 having a small number of defects, the pulling speed of the ingot 25 is set to V (mm / min), and the temperature in the ingot 25 near the interface 26 between the ingot 25 and the silicon melt 12. When the gradient is G (° C./mm), V / G (mm ² / Min · ° C). In this theory, as shown in FIG. 6, the relationship between V / G and the point defect concentration is plotted, where V / G is plotted on the horizontal axis and the vacancy type point defect density and the interstitial silicon point defect density are plotted on the same vertical axis. Is schematically illustrated, and it is explained that the boundary between the hole region and the interstitial silicon region is determined by V / G. More specifically, when the V / G ratio is equal to or higher than the critical point, an ingot 25 having a predominant vacancy type point defect concentration is formed, while when the V / G ratio is equal to or lower than the critical point, an ingot having an interstitial silicon type point defect concentration predominant is formed. 25 are formed. In FIG. 6, [I] is a region where interstitial silicon type point defects are dominant and where an aggregate of interstitial silicon type point defects is present ((V / G)). ₁ [V] is a region ((V / G) where the vacancy type point defects in the ingot 25 are dominant and the vacancy type point defect aggregates are present. ₂ Above, and [P] indicates a perfect region ((V / G)) where no aggregates of vacancy type point defects and no aggregates of interstitial silicon type point defects exist. ₁ ~ (V / G) ₂ ). In the region [V] adjacent to the region [P], the region [OSF] ((V / G) ₂ ~ (V / G) ₃ ) Exists.
[0026]
This perfect area [P] is further divided into the area [P _I ] And area [P _V ]are categorized. [P _I ] Means that the V / G ratio is above (V / G) ₁ To the critical point, [P _V ] Means that the V / G ratio is above the critical point (V / G) ₂ The area up to. That is, [P _I ] Is a region adjacent to the region [I] and having an interstitial silicon-type point defect concentration lower than the lowest interstitial silicon-type point defect concentration capable of forming interstitial dislocations. _V ] Is a region adjacent to the region [V] and having a vacancy type point defect concentration lower than the lowest vacancy type point defect concentration capable of forming an OSF. In the OSF, micro defects serving as nuclei are introduced during crystal growth, and become apparent in a thermal oxidation step or the like when manufacturing a semiconductor device, and cause a defect such as an increase in leak current of the manufactured device.
[0027]
Returning to FIG. 1, when pulling up the ingot 25 from the silicon melt 12, the plurality of adjusting plates 47 and 48 are respectively adjusted to rotate, and the ring-shaped space between the cylindrical body 46 and the ingot 25 is formed. By changing the cross-sectional area and changing the flow rate of the inert gas passing through this ring-shaped space, the silicon melt 12 near the meniscus 12a which is the boundary between the outer peripheral surface of the ingot 25 and the surface of the silicon melt 12 is formed. Changes the generated convection. The change in the convection generated in the silicon melt 12 in the vicinity of the meniscus 12a is obtained in advance by pulling up the ingot by simulation or pulling up the ingot by experiment.
[0028]
Specifically, when a small and slow convection 12b as shown in FIG. 17 is generated in the silicon melt 12 near the meniscus 12a, the wires 50a are fed out by a winch and the adjusting plates 47 and 48 are moved to the positions shown in FIG. By rotating the cylindrical body 46 in the direction indicated by the dashed arrow, the cylindrical body 46 is translated in a direction approaching the outer peripheral surface of the ingot 25. This narrows the ring-shaped space, so that the flow velocity of the inert gas flowing down the ring-shaped space increases, and the flow velocity of the inert gas flowing along the surface of the meniscus 12a also increases. As a result, the convection 12b generated in the silicon melt 12 in the vicinity of the meniscus 12a becomes larger and faster as shown in FIG. 1 as the flow rate of the inert gas increases, and descends near the meniscus 12a and Since the temperature rises near the center of the solid-liquid interface 12c, the solid-liquid interface 12c becomes convex, and the temperature gradient in the vertical direction near the center of the solid-liquid interface 12c increases. Accordingly, the difference between the temperature gradient in the vertical direction near the center of the solid-liquid interface 12c and the temperature gradient in the vertical direction near the periphery of the solid-liquid interface 12c becomes small, and the pulled ingot 25 is moved in its radial direction and its longitudinal direction. Defect-free over high quality.
[0029]
On the other hand, when a large and fast convection 12b is generated near the surface of the silicon melt 12 away from the meniscus 12a as shown in FIG. 18, the wires 50a are wound by a winch to adjust the adjustment plates 47 and 48. By rotating the cylindrical body 46 in the direction indicated by the one-dot chain line arrow, the cylindrical body 46 is moved in parallel in a direction away from the outer peripheral surface of the ingot 25. Accordingly, the ring-shaped space is widened, so that the flow rate of the inert gas flowing down the ring-shaped space is reduced, and the flow rate of the inert gas flowing from the surface of the meniscus 12a to the surface of the silicon melt 12 is also reduced. . As a result, the convection 12b generated near the surface of the silicon melt 12 away from the meniscus 12a moves to the position shown in FIG. 1 with the decrease in the flow rate of the inert gas, and descends near the meniscus 12a. Since the temperature rises near the center of the solid-liquid interface 12c, the solid-liquid interface 12c becomes upwardly convex, and the temperature gradient in the vertical direction near the center of the solid-liquid interface 12c increases. Accordingly, the difference between the temperature gradient in the vertical direction near the center of the solid-liquid interface 12c and the temperature gradient in the vertical direction near the periphery of the solid-liquid interface 12c becomes small, and the pulled ingot 25 is moved in its radial direction and its longitudinal direction. Defect-free over high quality. By bringing the cylindrical body 46 closer to the outer peripheral surface of the ingot 25 or separating it from the outer peripheral surface of the ingot 25 in accordance with the change of the convection 12b of the silicon melt 12, the ingot 25 pulled up has high quality without defects. Can be enlarged in the longitudinal direction.
[0030]
7 to 11 show a second embodiment of the present invention. 7 to 11, the same reference numerals as those in FIGS. 1 to 5 indicate the same parts.
In this embodiment, a plurality of rectifying plates 64 are provided between the outer peripheral surface of the ingot 25 and the inner peripheral surface of the bulging portion 41, and the upper ends of these rectifying plates 64 are the tips of the plurality of adjusting plates 67 and 68. The bases of the adjusting plates 67 and 68 are respectively mounted on the inclined upper surface of the bulging portion 41 so as to be movable along this surface. Similar to the first embodiment, the plurality of rectifying plates 64 have eight rectangular plate-shaped inner rectifying plates (not shown) and eight outer rectifying plates 64 (FIG. 7). By disposing the inner rectifying plate and the outer rectifying plate 64 as described above, the cylindrical body 66 that is larger than the outer diameter of the ingot 25 and smaller than the inner diameter of the cylindrical portion 37 and surrounds the outer peripheral surface of the ingot 25 is configured. .
[0031]
The plurality of adjustment plates 67 and 68 are respectively mounted on the inclined upper surface of the bulging portion 41 so as to be movable in the radial direction of the ingot 25 at predetermined intervals in the circumferential direction, and have eight outer rectifiers at the tips. The upper ends of the plates 44 are pivotally attached to eight lower trapezoidal plate-like lower adjustment plates 68, respectively, and are positioned between adjacent lower adjustment plates 68 so that both side edges overlap the side edges of the adjacent lower adjustment plate 68. The base portion is mounted on the inclined upper surface of the bulging portion 41 so as to be movable along this surface, and the upper ends of eight inner rectifying plates are respectively pivotally attached to the front ends thereof. 67 (FIGS. 7 to 11). By disposing the lower adjustment plate 68 and the upper adjustment plate 67 as described above, the cone body 69 that closes the gap between the tubular body 66 formed by the plurality of rectifying plates 64 and the bulging portion 41 is formed. Be composed.
[0032]
A long hole 68a extending in the radial direction of the ingot 25 is formed at the center of the lower adjustment plate 68, and a guide pin 68b attached to the inclined upper surface of the bulging portion 41 is loosely inserted into the long hole 68a. A rolling roller 68c, which partially projects from the inclined upper surface and receives the lower adjustment plate 68, is rotatably embedded in the inclined upper surface of the bulging portion 41. Thus, the lower adjustment plate 68 is guided by the guide pins 68b so as to be able to reciprocate on the rolling rollers 68c in the radial direction of the ingot 25.
[0033]
Further, the plurality of adjusting plates 67 and 68 are driven and controlled by adjusting plate driving means 70 (FIGS. 7 and 11). The adjusting plate driving means 70 includes 16 wires 70a whose lower ends are respectively attached to the base ends of the lower adjusting plate 68 and the upper adjusting plate 67 and whose upper ends are respectively routed outside the chamber, and 16 wires 70a provided outside the chamber. And a winch (not shown) for winding out the wire 70a so as to be able to be fed out. Reference numeral 70b in FIGS. 7 and 11 denotes a guide roller for guiding the wire 70a from the inclined upper surface of the bulging portion 41 along the inner surface of the cylindrical portion 37. Note that the vertical lengths of the inner rectifying plate and the outer rectifying plate 64 are such that the lower ends of these rectifying plates 64 approach the surface of the silicon melt 12 when the cylindrical body 66 is brought close to the outer peripheral surface of the ingot 25. Is set so that a predetermined gap is left. Except for the above, the configuration is the same as that of the first embodiment.
[0034]
A method for pulling up an ingot using the device configured as described above will be described.
When a small and slow convection 12b as shown in FIG. 17 is generated in the silicon melt 12 near the meniscus 12a, when the wire 70a is fed out by the winch, the adjusting plates 67 and 68 cause the inclination of the bulging portion 41 to be inclined. In order to move the upper surface in the direction indicated by the dashed arrow in FIG. 7, that is, in the direction going down the inclined upper surface, the cylindrical body 66 moves parallel to the direction approaching the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction.
[0035]
On the other hand, when a large and fast convection 12b as shown in FIG. 18 is generated near the surface of the silicon melt 12 away from the meniscus 12a, when the wire 70a is wound by the winch, the adjusting plates 67 and 68 become In order to move the inclined upper surface of the bulging portion 41 in the direction indicated by the one-dot chain line arrow in FIG. 7, that is, in the direction ascending the inclined upper surface, the cylindrical body 66 moves in parallel in a direction away from the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction. By bringing the cylindrical body 66 closer to the outer peripheral surface of the ingot 25 or separating it from the outer peripheral surface of the ingot 25 according to the change of the convection 12b of the silicon melt 12, the defect-free and high quality of the ingot 25 pulled up can be improved. Can be enlarged in the longitudinal direction. In this embodiment, since the plurality of adjusting plates 67 and 68 are always kept along the upper surface of the bulging portion 41, the inert gas flowing down between the ingot 25 and the cylindrical portion 37 is used as the first gas. It can be guided between the ingot 25 and the tubular body 46 more quickly than in the embodiment.
[0036]
12 to 14 show a third embodiment of the present invention. 12 to 14, the same reference numerals as those in FIGS. 1 to 5 indicate the same parts.
In this embodiment, a plurality of rectifying plates 74 are provided between the outer peripheral surface of the ingot 25 and the inner peripheral surface of the bulging portion 41, and the upper ends of these rectifying plates 74 are the tips of the plurality of adjusting plates 77 and 78. And the bases of the adjusting plates 77 and 78 are respectively mounted on the inclined lower surface of the bulging portion 41 so as to be movable along this surface. Similar to the first embodiment, the plurality of rectifying plates 74 include eight rectangular plate-shaped inner rectifying plates (not shown) and eight outer rectifying plates 74 (FIG. 12). By disposing the inner rectifying plate and the outer rectifying plate 74 as described above, a cylindrical 76 body that is larger than the outer diameter of the ingot 25 and smaller than the inner diameter of the cylindrical portion 37 and surrounds the outer peripheral surface of the ingot 25 is configured. . The tubular body 76 is provided between the outer peripheral surface of the ingot 25 and the downwardly extending surface of the inner peripheral surface of the bulging portion 41.
[0037]
The plurality of adjusting plates 77 and 78 are respectively mounted on the inclined lower surface of the bulging portion 41 at predetermined intervals in the circumferential direction so as to be movable in the radial direction of the ingot 25, and have eight outer rectifiers at the tips. The upper ends of the plates 74 are pivotally attached to eight substantially trapezoidal plate-shaped lower adjustment plates 78, and are located between adjacent lower adjustment plates 78 so that both side edges overlap the side edges of the adjacent lower adjustment plate 78. The base portion is mounted on the inclined lower surface of the bulging portion 41 so as to be movable along this surface, and the upper ends of eight inner rectifying plates are pivotally attached to the ends thereof, and each of the eight upper adjusting plates is substantially trapezoidal. 77 (FIGS. 12 to 14). By disposing the lower adjustment plate 78 and the upper adjustment plate 77 as described above, the cone body 79 that closes the gap between the tubular body 76 formed by the plurality of rectifying plates 74 and the bulging portion 41 is formed. Be composed.
[0038]
A long hole 78a extending in the radial direction of the ingot 25 is formed at the center of the lower adjustment plate 78, and a guide pin 78b attached to the inclined lower surface of the bulging portion 41 is loosely inserted into the long hole 78a. A rolling roller 78c that receives the lower adjustment plate 78 is rotatably attached to the lower end of the guide pin 78b. As a result, the lower adjustment plate 78 is guided by the guide pins 78b so as to be able to reciprocate on the rolling rollers 78c in the radial direction of the ingot 25.
[0039]
Further, the plurality of adjusting plates 77 and 78 are driven and controlled by the adjusting plate driving means 70 (FIGS. 12 and 14). The adjusting plate driving means 70 includes 16 wires 70a whose lower ends are respectively attached to the base ends of the lower adjusting plate 78 and the upper adjusting plate 77 and whose upper ends are respectively routed outside the chamber, and 16 wires 70a provided outside the chamber. And a winch (not shown) for winding out the wire 70a so as to be able to be fed out. Reference numeral 70b in FIGS. 12 and 14 denotes a guide roller that guides the wire 70a from the inclined lower surface of the bulging portion 41, through the outer surface of the bulging portion 41, and along the outer surface of the cylindrical portion 37. Note that the vertical lengths of the inner rectifying plate 74 and the outer rectifying plate 74 are such that the lower ends of the rectifying plates 74 approach the surface of the silicon melt 12 when the cylindrical body 76 is brought close to the outer peripheral surface of the ingot 25. Is set so that a predetermined gap is left. Except for the above, the configuration is the same as that of the first embodiment.
[0040]
A method for pulling up an ingot using the device configured as described above will be described.
When a small and slow convection 12b as shown in FIG. 17 is generated in the silicon melt 12 near the meniscus 12a, when the wire 70a is fed out by the winch, the adjusting plates 77 and 78 cause the inclination of the bulging portion 41 to be inclined. By moving the lower surface in the direction indicated by the dashed arrow in FIG. 12, that is, in the direction going down the inclined lower surface, the cylindrical body 76 moves in parallel in the direction approaching the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction.
[0041]
On the other hand, when a large and fast convection 12b as shown in FIG. 18 is generated near the surface of the silicon melt 12 away from the meniscus 12a, when the wire 70a is wound by the winch, the adjusting plates 77 and 78 are moved. By moving the inclined lower surface of the bulging portion 41 in the direction indicated by the one-dot chain line arrow in FIG. 12, that is, in the direction going up the inclined lower surface, the cylindrical body 76 moves in parallel in a direction away from the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction. By bringing the cylindrical body 76 closer to the outer peripheral surface of the ingot 25 or separating it from the outer peripheral surface of the ingot 25 in accordance with the change in the convection 12b of the silicon melt 12 as described above, the defect-free and high quality of the ingot 25 pulled up can be improved. Can be enlarged in the longitudinal direction. In this embodiment, since the plurality of adjusting plates 77 and 78 are always kept along the lower surface of the bulging portion 41, the inert gas along the outer peripheral surface of the ingot 25 facing the bulging portion 41. Only the flow rate of the inert gas in the vicinity of the meniscus 12a can be changed without changing the flow rate, and the inert gas is prevented from swinging by increasing the flow rate of the inert gas throughout the chamber 11. The effect that can be obtained is obtained.
[0042]
FIG. 15 shows a fourth embodiment of the present invention. 15, the same reference numerals as those in FIG. 7 indicate the same parts.
In this embodiment, the upper surface of the bulging portion 81 is formed horizontally, and the plurality of adjusting plates 67 and 68 are configured to be able to move on the upper surface of the horizontal bulging portion 81 in the radial direction of the ingot 25. The adjustment plates 67 and 68 are driven and controlled by the adjustment plate driving means 80. The adjustment plate driving means 80 has 16 first wires 80a each having one end attached to the base end of the lower adjustment plate 68 and the base end of the upper adjustment plate 67, and the other end respectively routed outside the chamber, and one end having the lower adjustment. Sixteen second wires 80b attached to the lower surfaces of the center of the plate 68 and the upper adjustment plate 67 and the other ends are respectively routed outside the chamber, and the first and second wires 80a, 80b provided outside the chamber. And a winch (not shown) that winds the sheet so as to be able to be fed out. Reference numeral 80c in FIG. 15 is a guide roller that guides the first wire 80a and the second wire 80b along the bulging portion 81 and the cylindrical portion 37. Except for the above, the configuration is the same as that of the second embodiment.
[0043]
A method for pulling up an ingot using the device configured as described above will be described.
When the small and slow convection 12b as shown in FIG. 17 is generated in the silicon melt 12 near the meniscus 12a, the first wire 80a is fed out by the winch and the second wire 80b is wound, and the adjusting plate 67 , 68 move on the upper surface of the bulging portion 81 in the direction indicated by the dashed arrow, so that the cylindrical body 66 moves in parallel in a direction approaching the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction.
[0044]
On the other hand, when a large and fast convection 12b as shown in FIG. 18 is generated near the surface of the silicon melt 12 away from the meniscus 12a, the first wire 80a is wound by the winch and the second wire 80b is wound. When extended, the adjusting plates 67 and 68 move on the upper surface of the bulging portion 81 in the direction indicated by the dashed-dotted arrow, so that the cylindrical body 66 moves in parallel in a direction away from the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction. By bringing the cylindrical body 66 closer to the outer peripheral surface of the ingot 25 or separating it from the outer peripheral surface of the ingot 25 according to the change of the convection 12b of the silicon melt 12, the defect-free and high quality of the ingot 25 pulled up can be improved. Can be enlarged in the longitudinal direction. Note that the adjusting plate driving means 80 having the first and second wires 80a and 80b of the present embodiment has a configuration in which the upper surface of the bulging portion is not horizontal, and the upper surface of the bulging portion gradually moves toward the outer peripheral surface of the ingot 25. The present invention can also be applied to a case where the adjusting plate does not move down the upper surface of the bulging portion due to its own weight even if the wire is fed out by a winch.
[0045]
FIG. 16 shows a fifth embodiment of the present invention. 16, the same reference numerals as those in FIG. 12 indicate the same parts.
In this embodiment, the lower surface of the bulging portion 81 is formed horizontally, and the adjusting plates 77 and 78 are configured so that the lower surface of the horizontal bulging portion 81 can be moved in the radial direction of the ingot 25, and furthermore, these adjustments are made. The plates 77 and 78 are driven and controlled by the adjusting plate driving means 80. The adjustment plate driving means 80 includes 16 first wires 80a, one end of which is attached to the base end of each of the lower adjustment plate 78 and the upper adjustment plate 77, and the other end of which is routed outside the chamber. Sixteen second wires 80b attached to the central upper surfaces of the plate 78 and the upper adjustment plate 77, respectively, and the other ends thereof are routed outside the chamber, respectively, and the first and second wires 80a, 80b provided outside the chamber. And a winch (not shown) that winds the sheet so as to be able to be fed out. Reference numeral 80c in FIG. 16 is a guide roller that guides the first wire 80a and the second wire 80b along the bulging portion 81 and the cylindrical portion 37. Except for the above, the configuration is the same as that of the third embodiment.
[0046]
A method for pulling up an ingot using the device configured as described above will be described.
When a small and slow convection 12b as shown in FIG. 17 is generated in the silicon melt 12 in the vicinity of the meniscus 12a, when the first wire 80a is fed out by the winch and the second wire 80b is wound, the adjustment plate 77 is formed. , 78 move on the lower surface of the bulging portion 81 in the direction indicated by the dashed arrow, so that the cylindrical body 76 moves in parallel in a direction approaching the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction.
[0047]
On the other hand, when a large and fast convection 12b as shown in FIG. 18 is generated near the surface of the silicon melt 12 away from the meniscus 12a, the first wire 80a is wound by the winch and the second wire 80b is wound. When extended, the adjusting plates 77 and 78 move on the lower surface of the bulging portion 81 in the direction indicated by the dashed-dotted arrow, so that the cylindrical body 76 moves in parallel in a direction away from the outer peripheral surface of the ingot 25. As a result, as in the first embodiment, the solid-liquid interface 12c has an upward convex shape, so that the pulled ingot 25 is defect-free and of high quality in its radial direction and its longitudinal direction. By bringing the cylindrical body 76 closer to the outer peripheral surface of the ingot 25 or separating it from the outer peripheral surface of the ingot 25 in accordance with the change of the convection 12b of the silicon melt 12 as described above, the pulled-up ingot 25 has high quality without defects. Can be enlarged in the longitudinal direction. Note that the adjusting plate driving means 80 having the first and second wires 80a and 80b of the present embodiment has a structure in which the lower surface of the bulging portion 81 is not horizontal, and the lower surface of the bulging portion is gradually loosened toward the outer peripheral surface of the ingot. The present invention can be applied to a case where the adjustment plate is inclined at an appropriate angle, that is, even if the wire is fed out by the winch, the adjustment plate does not move down the lower surface of the bulging portion due to its own weight.
[0048]
【The invention's effect】
As described above, according to the present invention, the ingot extends vertically between the outer peripheral surface of the ingot and the inner peripheral surface of the bulging portion or an extended surface of the inner peripheral surface and is provided so as to be movable in the radial direction of the ingot. A plurality of rectifying plates surround the outer peripheral surface of the ingot, and a plurality of adjusting plates having a base end or a base attached to the bulging portion and the upper ends of the rectifying plates pivotally mounted at the distal end are provided with the plurality of rectifying plates and the bulging plate. The gap between the parts is closed, and the adjusting plate driving means drives and controls the plurality of adjusting plates in accordance with the change of the convection of the silicon melt, so that a predetermined convection occurs in the silicon melt near the meniscus. When the plurality of current plates are brought closer to the outer peripheral surface of the ingot during the operation, the flow rate of the inert gas flowing between the plurality of current plates and the ingot increases. As a result, the flow rate of the inert gas flowing down the surface of the meniscus is increased, so that the silicon melt has a relatively large amount of falling near the meniscus and rising near the center of the solid-liquid interface between the silicon melt and the ingot. Convection occurs, and the solid-liquid interface becomes upwardly convex. Therefore, the difference between the vertical temperature gradient near the center of the solid-liquid interface and the vertical temperature gradient near the periphery of the solid-liquid interface is reduced, and the defect-free and high-quality portion of the pulled ingot is lengthened. Can expand in any direction.
[Brief description of the drawings]
FIG. 1 is an enlarged sectional view of a portion A in FIG. 5 showing a pulling device according to a first embodiment of the present invention.
FIG. 2 is a sectional view taken along line BB of FIG. 4;
FIG. 3 is a sectional view taken along line CC of FIG. 4;
FIG. 4 is a sectional view taken along line DD of FIG. 1;
FIG. 5 is a vertical sectional configuration diagram of the pulling device.
FIG. 6 shows an ingot in which the vacancy point defect concentration is dominant when the V / G ratio is above the critical point and the interstitial silicon point defect concentration when the V / G ratio is below the critical point, based on Bornkov's theory. The figure which shows that the ingot which is dominant is formed.
FIG. 7 is a sectional view showing a second embodiment of the present invention and corresponding to FIG. 1;
FIG. 8 is a sectional view taken along line EE of FIG. 7;
FIG. 9 is a sectional view taken along line FF of FIG. 8;
FIG. 10 is a sectional view taken along line GG of FIG. 8;
FIG. 11 is a sectional view taken along line HH of FIG. 7;
FIG. 12 is a sectional view illustrating a third embodiment of the present invention and corresponding to FIG. 1;
FIG. 13 is a sectional view taken along line II of FIG. 12;
FIG. 14 is a sectional view taken along line JJ of FIG. 13;
FIG. 15 is a sectional view showing a fourth embodiment of the present invention and corresponding to FIG. 7;
FIG. 16 is a sectional view showing a fifth embodiment of the present invention and corresponding to FIG. 12;
FIG. 17 is a cross-sectional view corresponding to FIG. 1, showing a state in which a small and slow convection occurs in a conventional silicon melt near a meniscus.
FIG. 18 is a cross-sectional view corresponding to FIG. 1, showing a state in which a large and fast convection occurs near the surface of a silicon melt away from a conventional meniscus.
[Explanation of symbols]
11 chambers
12 Silicon melt
12b convection
13 Quartz crucible
25 ingots
28 Gas supply and discharge means
36 Heat shield
37 tube
41, 81 bulge
43,44,64,74 Rectifier plate
47, 48, 67, 68, 77, 78 Adjustment plate
50, 70, 80 adjustment plate driving means
50a, 70a, 80a, 80b Wire

Claims (4)

チャンバ（１１）内に設けられシリコン融液（１２）が貯留された石英るつぼ（１３）と、前記石英るつぼ（１３）の外周面を包囲し前記シリコン融液（１２）を加熱するヒータ（１８）と、前記シリコン融液（１２）から引上げられるインゴット（２５）の外周面を包囲しかつ下端が前記シリコン融液（１２）表面から間隔をあけて上方に位置する筒部（３７）と前記筒部（３７）の下部内方に膨出して設けられた膨出部（４１）とを有する熱遮蔽部材（３６）と、前記チャンバ（１１）の上部から前記チャンバ（１１）の内部に不活性ガスを供給して前記膨出部（４１）と前記インゴット（２５）の間に不活性ガスを流下させる不活性ガス給排手段（２８）とを備えたシリコン単結晶引上げ装置において、
前記インゴット（２５）の外周面と前記膨出部（４１）の内周面又はこの内周面の延長面との間に鉛直方向に延びかつ前記インゴット（２５）の半径方向に平行移動可能にそれぞれ設けられ更に前記インゴット（２５）の外周面を包囲する複数の整流板（４３，４４）と、
基端又は基部が前記膨出部（４１）にそれぞれ取付けられかつ先端に前記複数の整流板（４３，４４，６４）の上端がそれぞれ枢着され更に前記複数の整流板（４３，４４，６４）及び前記膨出部（４１）間の隙間を塞ぐ複数の調整板（４７，４８，６７，６８）と、
前記シリコン融液（１２）の対流（１２ｂ）の変化に応じて前記複数の整流板（４３，４４，６４）を前記インゴット（２５）の外周面に近づけるか或いは前記インゴット（２５）の外周面から離すように前記複数の調整板（４７，４８，６７，６８）をそれぞれ駆動することにより前記インゴット（２５）と前記シリコン融液（１２）との固液界面（１２ｃ）が上凸状となるように制御する調整板駆動手段（５０，７０）と
を備えたことを特徴とする不活性ガスの流速制御装置。A quartz crucible (13) provided in the chamber (11) and containing the silicon melt (12); and a heater (18) surrounding the outer peripheral surface of the quartz crucible (13) and heating the silicon melt (12). And a cylindrical portion (37) surrounding the outer peripheral surface of the ingot (25) pulled up from the silicon melt (12) and having a lower end located above the silicon melt (12) surface at an interval from the surface. A heat shielding member (36) having a bulging portion (41) bulging inward at a lower portion of the cylindrical portion (37); and a heat shielding member (36) from the upper portion of the chamber (11). A silicon single crystal pulling apparatus comprising: an inert gas supply / discharge means (28) for supplying an active gas to flow an inert gas between the bulging portion (41) and the ingot (25);
It extends in the vertical direction between the outer peripheral surface of the ingot (25) and the inner peripheral surface of the bulging portion (41) or an extended surface of the inner peripheral surface, and is movable in parallel in the radial direction of the ingot (25). A plurality of rectifying plates (43, 44) each provided and further surrounding the outer peripheral surface of the ingot (25);
Base ends or bases are respectively attached to the bulging portions (41), and upper ends of the plurality of rectifying plates (43, 44, 64) are respectively pivotally attached to distal ends, and further, the plurality of rectifying plates (43, 44, 64) are provided. ) And a plurality of adjusting plates (47, 48, 67, 68) for closing the gap between the bulging portions (41);
The plurality of current plates (43, 44, 64) are brought closer to the outer peripheral surface of the ingot (25) or the outer peripheral surface of the ingot (25) according to the change in the convection (12b) of the silicon melt (12). The solid-liquid interface (12c) between the ingot (25) and the silicon melt (12) is made convex by driving each of the plurality of adjusting plates (47, 48, 67, 68) so as to separate from them. And an adjusting plate driving means (50, 70) for controlling the flow rate of the inert gas. 複数の調整板（４７，４８）の基端が膨出部（４１）の内周面にそれぞれ回動可能に取付けられ、調整板駆動手段（５０）が前記複数の調整板（４７，４８）をそれぞれ吊上げて前記複数の調整板（４７，４８）をこれらの基端を中心にそれぞれ回動させる複数のワイヤ（５０ａ）を有する請求項１記載の不活性ガスの流速制御装置。The base ends of the plurality of adjusting plates (47, 48) are rotatably mounted on the inner peripheral surface of the bulging portion (41), respectively, and the adjusting plate driving means (50) is provided with the adjusting plates (47, 48). The inert gas flow rate control device according to claim 1, further comprising a plurality of wires (50a) each of which lifts a respective one of the plurality of adjustment plates (47, 48) and rotates the plurality of adjustment plates (47, 48) around their base ends. 複数の調整板（６７，６８）の基部が膨出部（４１）の上面又は下面にこの上面又は下面に沿ってそれぞれ移動可能に取付けられ、調整板駆動手段（７０）が前記複数の調整板（６７，６８）を前記膨出部（４１）の上面又は下面に沿ってそれぞれ移動させる複数のワイヤ（７０ａ）を有する請求項１記載の不活性ガスの流速制御装置。The bases of the plurality of adjusting plates (67, 68) are movably attached to the upper surface or the lower surface of the bulging portion (41) along the upper surface or the lower surface, respectively, and the adjusting plate driving means (70) is provided with the adjusting plate driving means (70). The inert gas flow rate control device according to claim 1, further comprising a plurality of wires (70a) for moving the (67, 68) along the upper surface or the lower surface of the bulging portion (41), respectively. シリコン融液（１２）を貯留する石英るつぼ（１３）を所定の回転速度で回転させ、前記シリコン融液（１２）から引上げられるインゴット（２５）を包囲しかつ下端が前記シリコン融液（１２）表面から間隔をあけて上方に位置する筒部（３７）と前記筒部（３７）の下部内方に膨出して設けられた膨出部（４１）とを有する熱遮蔽部材（３６）を設け、前記チャンバ（１１）の上部から前記チャンバ（１１）の内部に不活性ガスを供給して前記膨出部（４１）と前記インゴット（２５）の間に不活性ガスを流下させつつ、前記インゴット（２５）内が格子間シリコン型点欠陥の凝集体及び空孔型点欠陥の凝集体の存在しないパーフェクト領域となる引上げ速度で前記インゴット（２５）を引上げるシリコン単結晶引上げ方法において、
前記インゴット（２５）の外周面と前記膨出部（４１）の内周面又はこの内周面の延長面との間に鉛直方向に延びかつ前記インゴット（２５）の半径方向に平行移動可能にそれぞれ設けられた前記複数の整流板（４３，４４，６４）が前記インゴット（２５）の外周面を包囲し、
基端又は基部を前記膨出部（４１）にそれぞれ取付けかつ先端に前記複数の整流板（４３，４４，６４）の上端をそれぞれ枢着した前記複数の調整板（４７，４８，６７，６８）が前記複数の整流板（４３，４４，６４）及び前記膨出部（４１）間の隙間を塞ぎ、
前記シリコン融液（１２）の対流（１２ｂ）の変化に応じて前記複数の整流板（４３，４４，６４）を前記インゴット（２５）の外周面に近づけるか或いは前記インゴット（２５）の外周面から離すように調整板駆動手段（５０，７０）が前記複数の調整板（４７，４８，６７，６８）をそれぞれ駆動することにより前記インゴット（２５）と前記シリコン融液（１２）との固液界面（１２ｃ）が上凸状となるように制御する
ことを特徴とする不活性ガスの流速制御方法。A quartz crucible (13) for storing the silicon melt (12) is rotated at a predetermined rotation speed to surround an ingot (25) pulled up from the silicon melt (12) and a lower end thereof is formed of the silicon melt (12). A heat shielding member (36) having a tubular portion (37) located above and spaced apart from the surface and a bulged portion (41) bulged inwardly below the tubular portion (37) is provided. And supplying an inert gas from the upper part of the chamber (11) to the inside of the chamber (11) to cause the inert gas to flow between the bulging portion (41) and the ingot (25). (25) A method for pulling a silicon single crystal in which the ingot (25) is pulled at a pulling speed at which a perfect region in which the aggregates of interstitial silicon type point defects and the aggregates of vacancy type point defects do not exist is provided.
It extends in the vertical direction between the outer peripheral surface of the ingot (25) and the inner peripheral surface of the bulging portion (41) or an extended surface of the inner peripheral surface, and is movable in parallel in the radial direction of the ingot (25). The plurality of straightening plates (43, 44, 64) provided respectively surround the outer peripheral surface of the ingot (25),
The plurality of adjusting plates (47, 48, 67, 68) each having a base end or a base attached to the bulging portion (41) and the upper ends of the plurality of rectifying plates (43, 44, 64) pivotally attached to the distal end. ) Closes the gap between the plurality of current plates (43, 44, 64) and the bulging portion (41),
The plurality of current plates (43, 44, 64) are brought closer to the outer peripheral surface of the ingot (25) or the outer peripheral surface of the ingot (25) according to the change in the convection (12b) of the silicon melt (12). The adjusting plate driving means (50, 70) respectively drives the plurality of adjusting plates (47, 48, 67, 68) so as to separate from the ingot (25) and the silicon melt (12). A method for controlling the flow rate of an inert gas, characterized in that the liquid interface (12c) is controlled so as to be convex upward.

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