JP2004327359A - Light irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light irradiation device equipped with a flash lamp capable of avoiding the lowering of luminance on a lighted surface even in a case of lighting a lamp with a short pulse, completing a process of a work, and reducing the frequency of a lamp exchanging work. <P>SOLUTION: The light irradiation device for irradiating a lamp light on an object to be irradiated comprises flash lamps each composed of a light-emitting tube made of silica glass, trigger members arranged on the lamps in a direction of tube axis, and a power source supplying power to the lamps. The flash lamp is lighted with an irradiation energy of ≥65 kW/cm<SP>2</SP>and a pulse width of ≤300 μs. The trigger members are located at a position near to the outer peripheral part of the light-emitting tubes facing the object to be irradiated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

ここで、２０Ｊ／ｃｍ^２は単位面積当たりの光のエネルギー、３００μｓは発光の時間であり、よって、６６．７ｋＷ／ｃｍ^２は発光時間中のエネルギーである。発光時間（パルス幅）を３００μｓより短くすると照射エネルギーは更に増大し、例えば、発光時間１００μｓにおける照射エネルギーを算出すると、１１０ｋＷ／ｃｍ^２という非常に大きな値になる。
【００１５】
そして、発光管から放出された蒸発物が発光管の管壁に付着することにより、白濁が引き起こされるようになる。ここで、発光管からの蒸発物は、発光管内部において比較的低温部分に付着する傾向にあり、プラズマ発生部から遠い部分、つまり、トリガー部材が位置された面と相対する発光管内壁において堆積するようになる。このため、ランプの白濁は、トリガー部材が配置されていない発光管の側面部分において顕著に生じるようになる。
【００１６】
本発明によれば、トリガー部材が発光管の外周部近傍において被処理物に面した位置に配置されているので、発光管の被処理物側の面においては白濁を抑えることができ、電極間で発生した光が白濁によって遮光されるのを回避し、発光管を透過させて出射させることができ、被処理物の被処理面を照射することができるようになる。よって、ランプに白濁が発生しても、被処理物に対して照射する光の照度を高く維持することができるようになる。
【００１７】
【発明の実施の形態】
図１，図２は本発発明の第一の実施形態を説明する図であり、図１はランプの軸を通る面で切断した断面図、図２はランプの軸と直交する方向で切断した断面図である。
図１，２において、フラッシュランプ１（以下、簡単にランプ１ともいう。）は、発光管１０がシリカガラスからなり、内部にはキセノンガスが２７ｋＰａ〜８０ｋＰａ（２００Ｔｏｒｒ〜６００Ｔｏｒｒ）（２５℃換算）封入されている。発光管１０内部において陰極１１と陽極１１’（以下簡単に電極ともいう。）が対向配置され、各電極１１，１１’に連設されたリード棒１２，１２’が前記発光管１０の両端から気密に導出されている。
【００１８】
トリガー部材２は、両端が封止されたガラス管２０１の内部に金属線２０２が封装されてなり、該金属線２０２に電気的に接続された給電線２０３がガラス管２０１の片端部から導出されて構成されている。トリガー部材２は、フラッシュランプ１における発光管１０の外周面に密着するよう配設され、ランプ点灯用の電源装置（図示省略）とは異なる電源装置（図示省略）に接続される。
【００１９】
図２に示すように、フラッシュランプ１，１，・・は同一面上に同ピッチとなるよう並べて配置されており、その上方には内側に反射面が形成されたミラー部材３が配置されている。一方、ランプ１，１，・・の下方にはステージＳが位置されており、当該ステージＳ上には被処理物Ｗが載置されるようになる。
【００２０】
図２において線分Ｐは、ランプ１，１，・・の発光管１０，１０，・・と被処理物とを最短で結ぶ仮想線分であり、トリガー部材２，２，・・は、この仮想線分Ｐ上において発光管１０，１０，・・の外周面に沿って配置されている。
このように、トリガー部材２，２，・・は、発光管１０，１０，・・の外周部近傍において被処理物に面した位置に配置されているので、フラッシュランプ１，１，・・からの放射光は、一部がトリガー部材２，２，・・で遮光されて被処理物Ｗの被処理面に到達するようになるが、ランプ１，１，・・の点灯回数を重ねたとしても、係るトリガー部材２，２，・・近傍においては発光管１０，１０，・・に白濁が生じ難いので、被処理物Ｗに対する照度の低下を抑制でき、即ち長期にわたり被処理物に高い照度で光を照射できるので、ランプ１，１，・・の交換時期を遅らせることができるようになる。
【００２１】
ここで、図３を参照してランプが白濁する様子を詳細に説明する。尚、同図は、図２に記載されたランプを１本取り出して示したものである。
アニール処理を目的としてランプ１を点灯する場合、より短パルスで点灯しようとすると、プラズマの温度が上がり光のピーク強度も高くなる。トリガー部材２に負の電位の高い電圧が印加されると、放電によって生じるプラズマはトリガー部材２に引き寄せられ、発光管１０内部でもトリガー部材２の近傍部分１０Ａに集中する。発光管１０は、プラズマにより熱伝導と光吸収の作用によって部分的に高温に加熱され、その結果発光管１０を構成するシリカガラスがトリガー部材２の近傍部分１０Ａにおいて蒸発する。
蒸発物は、発光管１０内部を図矢印で示すようにプラズマ発生部から離れるように低温部に向かって浮遊し、発光管１０の内壁に付着して堆積する。このように蒸発物が発光管１０内壁に堆積することによって白濁が引き起こされる。
【００２２】
本実施形態によれば、トリガー部材は、発光管の外周部近傍において被処理物に面した位置に配置されているので、当該部分において発光管への蒸発物の付着が抑えられ、白濁を抑制することが可能となる。そして、被処理物の表面にランプからの放射光が直接照射されるため、被処理物に対し加熱処理を効率よく行うことができ、１回の閃光照射で所期の熱処理を達成させることができるようになる。
【００２３】
以下、上記実施形態とは異なる実施形態について、図４〜図６を参照して説明する。以下の説明において、上記１〜３で説明した構成と同様の構成については同じ符号を用いて記載し、その詳細な説明を省略する。尚、これらの図において、符号Ｘ，Ｘ’は、発光管からの蒸発物が浮遊し、付着しやすい部分を示し、白濁の程度が比較的小さい部分にＸ、より大きい部分にＸ’をそれぞれ付している。
【００２４】
図４は本発明に係る１本のランプを具備した光照射装置の実施形態を説明する図である。
図４（イ）において、上記第一の実施形態と同様、発光管１０の中心と被処理物Ｗとを最短で結ぶ仮想線分上にトリガー部材２１が配置された例であり、この例においてもトリガー部材２１は発光管１０の外周部近傍において被処理物Ｗに面した位置に配置されている。白濁する部分はトリガー部材２１が配置されていない略半円筒状の側面部分（Ｘ）である。
ランプにおける照度維持特性の向上を図ることができる効果は、ランプの本数によらず第一の実施形態と同様に得ることができる。
図４（ロ）は、トリガー部材を発光管の外周部近傍において被処理物に面した位置に配置し、上記（イ）のものに比較して発光管１０の周方向にずらして配置した例である。この実施形態においても上記（イ）のものと同様、トリガー部材２１が配置されていない略半円筒状の側面部分（Ｘ）において白濁が発生しやすい。しかるに、トリガー部材２１が被処理物Ｗに面した発光管１０外周部近傍に配置されているので、発光管１０の被処理物Ｗに面した部分が光透過性を有しており、更に、発光管１０と被処理物Ｗとの間にトリガー部材２１が配置されていないので、被処理物Ｗに対して良好な光照射を行えるようになる。
図４（ハ）は、１本のランプ１に対して２個のトリガー部材２１，２１’を、発光管１０の外周部近傍において被処理物Ｗに面した位置に配置した例である。トリガー部材２１，２１’には同じタイミングで同電位の電圧が印加される。発光管１０の白濁部分は被処理物Ｗ側とはちょうど反対側の面のごく一部分（Ｘ’）において顕著に生じ、そのほかの部分においては良好な光透過性を示す。よって、被処理物Ｗに対して長期にわたり高い照度で光を照射でき、被処理物Ｗにランプ１からの放射光を直接照射できて、所期の熱処理を高効率に行うことができるようになる。
【００２５】
図５は本発明に係る、２本のランプを具備した光照射装置の実施形態を説明する図である。
図５（イ）において、並行に配置された２本のランプ１ａ，１ｂの間に、トリガー部材２２ａｂが具備されている。トリガー部材２２ａｂは、両方の発光管１０ａ，１０ｂの外周部近傍において被処理物Ｗに面した位置に配置されている。
このようにトリガー部材２２ａｂの個数をランプ１ａ，１ｂの本数よりも少なくすることで、トリガー部材２２ａｂへ給電構造の簡便化を図ることができる。無論、この実施形態においても、発光管１０の被処理物Ｗに面した部分においては光透過性を有しており、被処理物Ｗに対して良好な光照射を行えるようになる。
図５（ロ）は、ランプ１ａに単独で作用するトリガー部材２２ａと、ランプ１ｂに単独で作用するトリガー部材２２ｂと、をそれぞれ発光管の外周部近傍において被処理物Ｗに面した位置に設けた例である。トリガー部材２２ａ，２２ｂが配置されているランプ１ａ，１ｂの両方の側面においては白濁の程度が小さいので、被処理物Ｗの縁部近傍の照度低下を防止できて照度分布をフラットにすることができる。
図５（ハ）は、ランプ１ａ，１ｂに対して３個のトリガー部材２２ａ，２２ａｂ，２２ｃを配置した例である。無論、この実施形態においてもトリガー部材２２ａ，２２ａｂ，２２ｃは、発光管１０，１０の外周部近傍において被処理物Ｗに面した位置に配置されている。これらトリガー部材２２ａ，２２ｂ，２２ｃには同じタイミングで同電位の電圧が印加される。この実施形態によれば、上記図４（ハ）で示したものと同様、白濁は発光管１０，１０の被処理物Ｗとちょうど反対側の面のごく一部分（Ｘ’）において顕著に生じるが、そのほかの部分においては良好な光透過性を示す。よって、被処理物Ｗにランプ１ａ，１ｂからの放射光を直接照射できて処理を極めて高効率に行うことができるようになる。
【００２６】
図６は、本発明に係る、３本のランプを具備した光照射装置の実施形態を説明する図である。
図６（イ）において、３本のランプ１ａ，１ｂ，１ｃを具備し、ランプ１ａに対して作用するトリガー部材２３ａと、ランプ１ｂ，１ｃに対して作用するトリガー部材２３ｂｃを具備している。この例においても、トリガー部材２３ａ，２３ｂｃが発光管１０，１０，１０の外周部近傍において被処理物Ｗに面した位置に配置されていることにより、各発光管１０，１０，１０の被処理物Ｗに面した部分が光透過性を有するようになる。
図６（ロ）は、ランプ１ａ，１ｂ，１ｃを具備しており、隣接するランプとランプの間にトリガー部材２３ａｂ，２３ｂｃを配設し、更にこれらを発光管１０，１０，１０の外周部近傍において被処理物Ｗに面した位置に配置した例である。これらトリガー部材２３ａｂ，２３ｂｃには同じタイミングで同電位の電圧が印加され、トリガー部材２３ａｂがランプ１ａ，１ｂに、トリガー部材２３ｂｃがランプ１ｂ，１ｃにそれぞれ作用する。ランプ１ａ，１ｃの発光管１０，１０にはそれぞれ、各トリガー部材２３ａ，２３ｂｃが配置されていない略半円筒状の側面部分（Ｘ，Ｘ）において白濁が発生しやすく、ランプ１ｂの発光管には被処理物（Ｗ）側とはちょうど反対側の面のごく一部分（Ｘ’）において顕著に生じるようになる。この例においても、発光管１０，１０，１０の被処理物Ｗに面した部分が光透過性を有するようになるので、被処理物Ｗに対して良好な光照射を行える。
図６（ハ）は、上記（ロ）で示したトリガー部材（２３ａ，２３ｂｃ）に加え、ランプ１ａ，１ｃ外方にもそれぞれトリガー部材２３ａ，２３ｃを配置した例である。無論、全てのトリガー部材２３ａ，２３ａ，２３ｂｃ，２３ｃは、発光管１０，１０の外周部近傍において被処理物Ｗに面した位置に配置されている。ランプとランプの間に配置されたトリガー部材２３ａｂ，２３ｂｃの作用は、上記（ロ）のものと同様である。発光管１０，１０，１０白濁は被処理物Ｗとちょうど反対側の面のごく一部分（Ｘ’，Ｘ’，Ｘ’）において顕著に生じるが、発光管のそのほかの部分においては良好な光透過性を示すようになり、被処理物Ｗにランプ１ａ，１ｂ，１ｃからの放射光を直接照射できて、所期の処理を極めて高効率に行うことができるようになる。
【００２７】
図７は、本発明に係る、４本のランプを具備した光照射装置の実施形態を説明する図である。
図７（イ）においては、ランプ１ａ，１ｂ，１ｃ，１ｄを具備し、隣接するランプとランプの間の発光管１０，１０の外周部近傍において被処理物Ｗに面した位置にトリガー部材２４ａｂ，２４ｂｃ，２４ｃｄを配置した例である。これらトリガー部材２４ａｂ，２４ｂｃ，２４ｃｄには同じタイミングで同電位の電圧が印加される。トリガー部材２４ａｂはランプ１ａ，１ｂに、トリガー部材２４ｂｃはランプ１ｂ，１ｃに、トリガー部材２４ｃｄはランプ１ｃ、１ｄに、それぞれ作用する。両外側に配置されたランプ１ａ，１ｄの発光管１０，１０にはそれぞれ、各トリガー部材２４ａｂ，２４ｃｄとは反対側の略半円筒状の側面部分（Ｘ，Ｘ）において白濁が発生しやすく、ランプ１ｂ，１ｃの発光管には被処理物Ｗとちょうど反対側の面のごく一部分（Ｘ’，Ｘ’）において顕著に生じるようになる。この例においても、発光管１０，１０，１０，１０の被処理物Ｗに面した部分において光透過性を有する部分が形成され、被処理物Ｗに対して良好な光照射を行える。
図７（ロ）においては、ランプ１ａ，１ｂ，１ｃ，１ｄを具備し、ランプ１ａに対して作用するトリガー部材２４ａと、ランプ１ｂ，１ｃに共通し作用するトリガー部材２４ｂｃと、ランプ１ｄに対して作用するトリガー部材２４ｄとが具備され、各々ランプ１ａ，１ｂ，１ｃ，１ｄの発光管１０，１０，１０，１０の外周部近傍において被処理物Ｗに面した位置に配置された例である。ランプ１ａ，１ｂ，１ｃ，１ｄの各発光管１０，１０，１０，１０には、各トリガー部材２４ａ，２４ｂｃ，２４ｄが配置された面と反対側の略半円筒状の側面部分（Ｘ，Ｘ，Ｘ，Ｘ）において白濁が発生しやすいが、被処理物Ｗ側において光透過性を有するので、被処理物Ｗに対して長期にわたり光照射を行えるようになる。
図７（ハ）は、上記（イ）で示したものに加え、ランプ１ａ，１ｄの外方にもトリガー部材２４ａ，２４ｄをそれぞれ配置した例であり、全てのトリガー部材２４ａ，２４ａｂ，２４ｂｃ，２４ｃｄ，２４ｄが、発光管１０，１０，１０，１０の外周部近傍において被処理物Ｗに面した位置に配置された例である。ランプとランプの間に配置されたトリガー部材２４ａｂ，２４ｂｃ，２４ｃｄの作用は、上記（イ）と同様である。発光管１０，１０，１０，１０の白濁は被処理物Ｗとちょうど反対側の面のごく一部分（Ｘ’，Ｘ’，Ｘ’，Ｘ’）において顕著に生じるが、そのほかの部分においては良好な光透過性を示すようになる。よって、ランプ１ａ，１ｂ，１ｃ，１ｄからの放射光を被処理物Ｗに直接照射できて、所期の処理を極めて高い効率で行うことができるようになる。
【００２８】
以上、本発明の実施形態について説明したが上記においては適宜変更可能であることはいうまでもない。例えば、ランプの上部に配置された反射ミラーは必須の構成ではない。又、トリガー部材においては、誘電体で被覆されているものに限定されることなく金属線のみで構成しても良い。仮に誘電体で覆う場合も誘電体の材質はガラスに限定されことなく適宜である。
【００２９】
〔実験例〕
本発明の効果を実証するため実験例を行った。図８（イ）〜（ハ）は本実験例に用いた光照射装置を説明する図である。
図８（イ）〜（ハ）に示す各構成に従い、実施例１，２及び比較例に係る光照射装置を製作した。何れの光照射装置もランプを４本搭載しておりランプの仕様は全て同じである。
図８（イ）は、先に図７（ロ）で説明したものと同様にトリガー部材を配置したものであり、この装置を実施例１とした。
図８（ロ）は、図７（ハ）で説明したものと同様にトリガー部材を配置したものであり、この装置を実施例２とした。
図８（ハ）は、トリガー部材が被処理物に面した発光管外周部近傍に配置されていない、即ち、従来技術に係る光照射装置である。この装置を比較例とした。
図８中においてＬ１，Ｌ２は、ランプ１ａ〜１ｄからの波長２００〜８００ｎｍの光を検出する瞬時分光器であり、本実験においては、ウシオ電機社製 瞬時分光装置（ＵＳＲ−３０型）を使用した。これら二つの照度計Ｌ１，Ｌ２による測定値の平均（（Ｌ１＋Ｌ２）／２）を算出し、評価値とした。
【００３０】
以下、本実験例に用いたフラッシュランプ及びトリガー部材の各構成と、ランプ及びトリガー部材の駆動条件（点灯条件）を示す。
１．フラッシュランプ構成
〔発光管〕材質：シリカガラス、外径：１０．４ｍｍ、肉厚：１．２ｍｍ、全長：２００ｍｍ、
〔封入ガス〕ガス種：キセノン、ガス封入圧：６０ｋＰａ（４５０トール）（２５℃換算）、
〔電極〕陽極：タングステン、陰極：ランタン（Ｌａ）−タングステン合金、電極間距離（発光長）：１６０ｍｍ
実施例１，２及び比較例に係る各装置について、上記仕様のフラッシュランプをそれぞれ用意し、ランプのピッチが１２．４ｍｍ（発光管の間隙：２．０ｍｍ）として同一面上に並べて配置した。
２．トリガー部材構成
〔金属線〕材質：タングステン、線経：φ１．０ｍｍ
〔誘電体〕材質：シリカガラス、全長：２００、外径：φ３．０ｍｍ、肉厚０．７ｍｍ
３．駆動条件（点灯条件）
〔ランプ〕エネルギー：６５Ｊ／ｃｍ^２、電流：２５００Ａ、電圧：２４５０Ｖ（約６００ｋＷ）、パルス幅：３００μｓ
〔トリガー部材〕電圧：１０ｋＶ
【００３１】
上記実験の結果を図９に示す。同図においては、各光照射装置の照度特性を、各装置における点灯初期における照度をそれぞれ１．０として示す図であり、縦軸は照度（相対値）、横軸はランプの点灯回数である。
【００３２】
図９において、実施例１、実施例２及び比較例の各装置の照度は、約１０００回点灯後それぞれ０．９４、０．９７、０．８６になり、約５０００回点灯後はそれぞれ、０．９１、０．７４、０．５になった。
更に点灯し続けると、約１００００回点灯後、各装置の照度はそれぞれ、０．６７、０．９、０．３９となってしまった。
点灯回数１００００回を超えると、実施例１においても、ランプの発光管の白濁が進行したがこれによる照度低下は比較的緩慢であり、従来製品に比較して十分な改善が見られた。実施例２に係る装置では、発光管の被処理物に面する部分においては依然として白濁が発生しておらず、照度は０．９以上を維持していた。実施例２に係る装置では、点灯初期に比較してミラー部材側の発光管内壁が白濁したことにより、当該ミラー部材からの反射光が被処理物に到達しにくくなるが、その他の放射光は良好に被処理物に到達することができるので、極めて良好な照度維持特性を得ることができる。
比較例に係る従来型の装置では、早くも顕著な照度低下が見られた。比較例に係る装置では、ランプはトリガー部材近傍において光を放射するものの、当該箇所からの光はミラー部材で反射しても発光管の白濁部によって遮光されてしまうので結局被処理物を照射することができなくなる。このため、ランプの点灯を重ねていくと被処理物を直接照射する光に加え反射光までも照射できなくなる。
実施例１，２に係る装置では、ランプの点灯回数を重ねても、発光管の被処理物に面した部分に光透過性を有する部分が形成されているため、白濁による影響を回避できて照度の低下を抑制することができるようになる。
【００３３】
【発明の効果】
以上、説明したように、本発明によれば、アニール処理用として使用される光照射装置において、フラッシュランプを短パルスで点灯しても、トリガー部材は、発光管の外周部近傍において被処理物に面した位置に配置されているので、発光管における被処理物に面した部分において白濁を抑えることができて、ランプの点灯回数を重ね、発光管の白濁が著しくなった場合でも、ランプからの放射光を被処理物の表面に高い照度で照射することができる。よって、従来製品に比較してランプの交換時期を遅らせることができるので、ランプの交換回数も少なくて済み、工業的に利用可能な光照射装置を提供することができる。
【図面の簡単な説明】
【図１】本発発明の第一の実施形態を説明するランプの軸を通る面で切断した断面図である。
【図２】本発発明の第一の実施形態を説明するランプの軸と直交する方向で切断した断面図である。
【図３】ランプの白濁が発生する様子を説明する図である。
【図４】本発明に係る、１本のランプを具備した光照射装置の実施形態を説明する図である。
【図５】本発明に係る、２本のランプを具備した光照射装置の実施形態を説明する図である。
【図６】本発明に係る、３本のランプを具備した光照射装置の実施形態を説明する図である。
【図７】本発明に係る、４本のランプを具備した光照射装置の実施形態を説明する図である。
【図８】実験例に用いた光照射装置を説明する図である。
【図９】実験の結果を示す、ランプ点灯回数と照度維持率の特性を示す図である。
【符号の説明】
１ フラッシュランプ
１０ 発光管
１１ 陰極（電極）
１１’ 陽極（電極）
１２，１２’ リード棒
２ トリガー部材
２０１ ガラス管
２０１ａ 片端部
２０２ 金属線
２０３ 給電線
１ａ，１ｂ，１ｃ，１ｄ フラッシュランプ
２１，２１’ トリガー部材
２２ａ，２２ａｂ，２２ｃ トリガー部材
２３ａ，２３ａｂ，２３ｂｃ，２３ｃ トリガー部材
２４ａ，２４ａｂ，２４ｂｃ，２４ｃｄ，２４ｄ トリガー部材
３ ミラー部材
Ｓ ステージ
Ｗ 被処理物[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light irradiation device used for manufacturing a semiconductor or a thin film transistor using a flash lamp.
[0002]
[Prior art]
In the manufacture of semiconductors and thin film transistors using a flash lamp, technology for annealing is being developed. For example, in the step of forming a shallow diffusion layer (pn junction) on the surface of a silicon wafer (activating impurities by ion implantation), a light irradiation device using a flash lamp is used.
Annealing by flash light irradiation from a flash lamp uses a continuous spectrum, so the wafer or element is soft, and can be locally heated in the depth direction, and has a lower energy density per irradiation pulse than a laser, resulting in ablation. Is less likely to occur.
Techniques related to annealing using a flash lamp are described in, for example, JP-A-2002-198322 and JP-A-2001-319887. The light irradiation device is described in, for example, JP-A-2002-231488.
[0003]
For example, in the step of forming a diffusion layer on the surface of a silicon wafer, it is necessary to avoid problems such as the deterioration of the profile of the ion-implanted impurity and the volatilization of the formed pattern, and to obtain a favorable activated state of the impurity. Needed. In the manufacture of a thin film transistor for a liquid crystal display panel, a semiconductor film formed on a substrate is reliably and uniformly activated, an annealing treatment is achieved, excessive heating of the substrate is prevented, and expansion and contraction of the substrate are prevented. Heating must be performed to suppress the generation of "warpage".
[0004]
Generally, in order to heat-treat a semiconductor substrate, it is necessary to heat only the surface layer portion of the semiconductor substrate so as to increase the temperature to 1000 to 1400 ° C. Therefore, in a light irradiation device for heat treatment including a flash lamp device, Specifically, for example, for a short time of 700 μsec, 30 J / cm ² It is required to irradiate the semiconductor substrate, which is the object to be processed, with light having the above energy, and in order to achieve this, the peak energy input to the flash lamp is 5 × 10 ⁶ W extends.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-198322
[Patent Document 2]
JP-A-2001-319887
[Patent Document 3]
JP-A-2002-231488
[0006]
[Problems to be solved by the invention]
In recent years, it has been required to turn on a lamp with a shorter pulse width than in the past, for the purpose of reducing the influence on the substrate and lowering the energy applied to the lamp. For example, a lamp with a pulse width of 300 μm or less is required. It has been attempted to light up.
[0007]
However, it has been found that when the flash lamp is to be lighted by such a short pulse, the inner surface of the arc tube made of silica glass becomes turbid after starting the lighting, and the illuminance on the surface to be irradiated is extremely reduced. If the illuminance decreases, the intended heat treatment of the work cannot be completed by one flash irradiation, so in a device that turns on the flash lamp with a short pulse as described above, it is necessary to replace the lamp. It is necessary to do it frequently. Therefore, it cannot be used industrially.
[0008]
In view of the above circumstances, an object of the present invention is to provide a light irradiation device equipped with a flash lamp, which can avoid a decrease in illuminance on a surface to be irradiated even when the lamp is turned on with a short pulse, thereby completing the processing of a workpiece. An object of the present invention is to provide a light irradiation device capable of reducing the frequency of lamp replacement work.
[0009]
[Means for Solving the Problems]
The light irradiation device of the present invention includes a flash lamp including an arc tube made of silica glass, a trigger member arranged in a tube axis direction of the lamp, and a power supply for supplying power to the lamp, The flash lamp is irradiated with an irradiation energy of ² As described above, in the light irradiation device which is turned on with a pulse width of 300 μs or less and irradiates the object with light from the lamp, the trigger member is located at a position facing the object near an outer peripheral portion of the arc tube. Characterized by being arranged in
[0010]
[Action]
A conventionally known light irradiating device equipped with a flash lamp is a trigger member made of a metal wire along the arc tube axis of the flash lamp in order to prevent a light emission error, as disclosed in JP-A-2002-231488. Is provided. The trigger member is based on, for example, a technique proposed by the present applicant in Japanese Patent Application No. 2001-400622. Specifically, a metal wire is provided inside a straight tubular dielectric member having both ends sealed. A power supply line that is sealed and electrically connected to the metal wire is led out of the dielectric member.
[0011]
This trigger member is applied with a voltage of about -15 kV to the cathode, which is the ground potential, and about -20 kV to the anode. That is, at the start of discharge, it is the lowest voltage part of the whole lamp. The reason for applying an extremely high pressure to the trigger member in this way is to surely start the discharge, and to use a metal wire installed in a form included in a silica glass tube outside the lamp as a trigger, This is because a voltage must be applied to the discharge space beyond a dielectric material called silica glass, and a large high pressure is required.
[0012]
The plasma generated by the discharge is, of course, at a positive potential with respect to the trigger member, and thus has the property of being drawn to the trigger member. As a result, a portion exposed close to the plasma is formed on the inner wall of the arc tube, and the arc tube is locally heated to a high temperature by the action of heat conduction and light absorption by the plasma.
[0013]
In the above-described light irradiation device, it is possible to effectively limit the light heating depth of the object to be processed (heat a shallow portion) by shortening the discharge time, that is, by shortening the pulse width. On the other hand, when the pulse width is shortened, the temperature of the plasma increases, and the peak intensity of light increases. For this reason, under the lighting conditions of the flash lamp for optically heating the silicon wafer, that is, under the lighting conditions satisfying the following equation, if the pulse width is reduced to, for example, 300 μs or less, the inner wall portion of the arc tube close to the plasma is reduced. Was heated excessively, leading to evaporation of the silica glass.
[0014]
(Equation 1)

Here, 20 J / cm ² Is the energy of light per unit area, 300 μs is the time of light emission, and thus 66.7 kW / cm ² Is the energy during the light emission time. When the light emission time (pulse width) is shorter than 300 μs, the irradiation energy further increases. For example, when the irradiation energy at a light emission time of 100 μs is calculated, 110 kW / cm ² This is a very large value.
[0015]
Then, the evaporated matter released from the arc tube adheres to the tube wall of the arc tube, causing cloudiness. Here, the evaporant from the arc tube tends to adhere to a relatively low temperature portion inside the arc tube, and is deposited on a portion far from the plasma generating portion, that is, on the inner wall of the arc tube facing the surface where the trigger member is located. I will do it. For this reason, the cloudiness of the lamp is remarkably generated on the side surface of the arc tube where the trigger member is not provided.
[0016]
According to the present invention, since the trigger member is arranged at a position facing the workpiece near the outer peripheral portion of the arc tube, cloudiness can be suppressed on the surface of the arc tube on the workpiece side, and the distance between the electrodes can be reduced. It is possible to prevent the light generated in step (1) from being blocked by white turbidity, transmit the light through the arc tube and emit the light, and irradiate the processing surface of the processing object. Therefore, even when the lamp becomes cloudy, the illuminance of light applied to the object can be maintained high.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 are diagrams illustrating a first embodiment of the present invention. FIG. 1 is a cross-sectional view taken along a plane passing through the axis of the lamp. FIG. 2 is a view taken along a direction perpendicular to the axis of the lamp. It is sectional drawing.
1 and 2, a flash lamp 1 (hereinafter, also simply referred to as a lamp 1) has an arc tube 10 made of silica glass, and a xenon gas inside thereof is 27 kPa to 80 kPa (200 Torr to 600 Torr) (converted to 25 ° C.). It is enclosed. A cathode 11 and an anode 11 ′ (hereinafter also simply referred to as electrodes) are arranged inside the arc tube 10, and lead rods 12, 12 ′ connected to the electrodes 11, 11 ′ are arranged from both ends of the arc tube 10. It is derived airtight.
[0018]
The trigger member 2 has a metal wire 202 sealed inside a glass tube 201 having both ends sealed, and a power supply line 203 electrically connected to the metal wire 202 is led out from one end of the glass tube 201. It is configured. The trigger member 2 is disposed so as to be in close contact with the outer peripheral surface of the arc tube 10 of the flash lamp 1, and is connected to a power supply device (not shown) different from a lamp lighting power supply device (not shown).
[0019]
As shown in FIG. 2, the flash lamps 1, 1,... Are arranged side by side on the same plane so as to have the same pitch, and a mirror member 3 having a reflection surface formed inside is disposed above the flash lamps 1, 1,. I have. On the other hand, a stage S is located below the lamps 1, 1,..., And the workpiece W is mounted on the stage S.
[0020]
In FIG. 2, a line segment P is an imaginary line segment connecting the arc tubes 10, 10,... Of the lamps 1, 1,. Are arranged along the outer peripheral surface of the arc tubes 10, 10,... On the virtual line segment P.
Since the trigger members 2, 2,... Are arranged at positions facing the workpiece in the vicinity of the outer peripheral portions of the arc tubes 10, 10,. Is partly shielded by the trigger members 2, 2,... And reaches the surface to be processed of the processing object W. However, assuming that the lighting times of the lamps 1, 1,. Also, in the vicinity of the trigger members 2, 2,..., The luminous bulbs 10, 10,. , The time for replacing the lamps 1, 1,... Can be delayed.
[0021]
Here, the manner in which the lamp becomes cloudy will be described in detail with reference to FIG. FIG. 3 shows one of the lamps shown in FIG.
In the case where the lamp 1 is turned on for the purpose of the annealing process, when the lamp is turned on with a shorter pulse, the temperature of the plasma increases and the peak intensity of the light increases. When a high voltage of a negative potential is applied to the trigger member 2, the plasma generated by the discharge is attracted to the trigger member 2, and also concentrates in the arc tube 10 in the vicinity 10 </ b> A near the trigger member 2. The arc tube 10 is partially heated to a high temperature by the action of heat conduction and light absorption by the plasma, and as a result, the silica glass constituting the arc tube 10 evaporates in the vicinity 10A of the trigger member 2.
The evaporant floats inside the arc tube 10 toward the low-temperature portion so as to be away from the plasma generating portion as shown by the arrow in the figure, and adheres and deposits on the inner wall of the arc tube 10. As described above, the evaporated matter is deposited on the inner wall of the arc tube 10 to cause cloudiness.
[0022]
According to the present embodiment, since the trigger member is disposed at a position facing the workpiece near the outer peripheral portion of the arc tube, the evaporation member is prevented from adhering to the arc tube in this portion, and cloudiness is suppressed. It is possible to do. In addition, since the surface of the object is directly irradiated with the radiated light from the lamp, the object can be efficiently heated, and the intended heat treatment can be achieved with a single flash irradiation. become able to.
[0023]
Hereinafter, an embodiment different from the above-described embodiment will be described with reference to FIGS. In the following description, the same components as those described in the above 1 to 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. In these figures, symbols X and X 'indicate portions where the evaporant from the arc tube floats and easily adheres. X indicates a portion where the degree of white turbidity is relatively small, and X' indicates a portion where the degree of cloudiness is relatively large. It is attached.
[0024]
FIG. 4 is a view for explaining an embodiment of a light irradiation device provided with one lamp according to the present invention.
FIG. 4A shows an example in which the trigger member 21 is arranged on an imaginary line connecting the center of the arc tube 10 and the workpiece W in the shortest manner, as in the first embodiment. Also, the trigger member 21 is disposed at a position facing the workpiece W near the outer peripheral portion of the arc tube 10. The opaque portion is a substantially semi-cylindrical side surface portion (X) where the trigger member 21 is not disposed.
The effect of improving the illuminance maintenance characteristics of the lamp can be obtained in the same manner as in the first embodiment regardless of the number of lamps.
FIG. 4B shows an example in which the trigger member is arranged at a position facing the workpiece in the vicinity of the outer peripheral portion of the arc tube, and is displaced in the circumferential direction of the arc tube 10 as compared with the above-mentioned (A). It is. Also in this embodiment, as in the case of the above (A), white turbidity is likely to occur on the substantially semi-cylindrical side portion (X) where the trigger member 21 is not disposed. However, since the trigger member 21 is disposed in the vicinity of the outer peripheral portion of the arc tube 10 facing the workpiece W, the portion of the arc tube 10 facing the workpiece W has light transmittance, and furthermore, Since the trigger member 21 is not disposed between the arc tube 10 and the workpiece W, the workpiece W can be irradiated with good light.
FIG. 4C shows an example in which two trigger members 21 and 21 ′ are arranged for one lamp 1 at positions near the workpiece W near the outer peripheral portion of the arc tube 10. The same potential voltage is applied to the trigger members 21 and 21 'at the same timing. The cloudy portion of the arc tube 10 is remarkably generated on a very small portion (X ′) of the surface just opposite to the workpiece W side, and the other portions show good light transmittance. Therefore, the object W can be irradiated with light with high illuminance over a long period of time, and the object W can be directly irradiated with the radiated light from the lamp 1, so that the intended heat treatment can be performed with high efficiency. Become.
[0025]
FIG. 5 is a diagram illustrating an embodiment of a light irradiation device including two lamps according to the present invention.
In FIG. 5A, a trigger member 22ab is provided between two lamps 1a and 1b arranged in parallel. The trigger member 22ab is arranged at a position facing the workpiece W near the outer peripheral portions of both the arc tubes 10a and 10b.
Thus, by making the number of the trigger members 22ab smaller than the number of the lamps 1a and 1b, it is possible to simplify the power supply structure to the trigger members 22ab. Of course, also in this embodiment, the portion of the arc tube 10 facing the processing object W has light transmittance, so that the processing object W can be favorably irradiated with light.
FIG. 5B shows a state in which a trigger member 22a acting solely on the lamp 1a and a trigger member 22b acting solely on the lamp 1b are provided at positions facing the workpiece W near the outer peripheral portion of the arc tube. This is an example. Since the degree of white turbidity is small on both side surfaces of the lamps 1a and 1b on which the trigger members 22a and 22b are arranged, it is possible to prevent a decrease in illuminance near the edge of the workpiece W and to make the illuminance distribution flat. it can.
FIG. 5C shows an example in which three trigger members 22a, 22ab, and 22c are arranged for the lamps 1a and 1b. Of course, also in this embodiment, the trigger members 22a, 22ab, and 22c are arranged at positions near the workpiece W near the outer peripheral portions of the arc tubes 10, 10. The same potential voltage is applied to these trigger members 22a, 22b, 22c at the same timing. According to this embodiment, as in the case shown in FIG. 4 (c), the white turbidity occurs remarkably on a very small portion (X ′) of the surface of the arc tubes 10, 10 just opposite to the workpiece W. In other parts, good light transmittance is exhibited. Therefore, the object W can be directly irradiated with the radiated light from the lamps 1a and 1b, and the processing can be performed with extremely high efficiency.
[0026]
FIG. 6 is a diagram illustrating an embodiment of a light irradiation device including three lamps according to the present invention.
In FIG. 6A, three lamps 1a, 1b and 1c are provided, and a trigger member 23a acting on the lamp 1a and a trigger member 23bc acting on the lamps 1b and 1c are provided. Also in this example, since the trigger members 23a, 23bc are arranged at positions facing the workpiece W near the outer peripheral portions of the arc tubes 10, 10, 10, each of the arc tubes 10, 10, 10 is processed. The portion facing the object W has light transmittance.
FIG. 6 (b) includes lamps 1a, 1b, 1c, trigger members 23ab, 23bc are arranged between adjacent lamps, and these are connected to the outer peripheral portions of the arc tubes 10, 10, 10. This is an example in which the device is arranged at a position facing the workpiece W in the vicinity. The same potential voltage is applied to the trigger members 23ab and 23bc at the same timing, and the trigger member 23ab acts on the lamps 1a and 1b, and the trigger member 23bc acts on the lamps 1b and 1c. The luminous bulbs 10 and 10 of the lamps 1a and 1c, respectively, are susceptible to cloudiness at the substantially semi-cylindrical side portions (X, X) where the trigger members 23a and 23bc are not disposed. Significantly occurs on a very small portion (X ′) of the surface just opposite to the object (W). Also in this example, since the portions of the arc tubes 10, 10, 10 facing the processing object W have optical transparency, it is possible to irradiate the processing object W with good light.
FIG. 6C shows an example in which, in addition to the trigger members (23a, 23bc) shown in (B) above, trigger members 23a, 23c are arranged outside the lamps 1a, 1c, respectively. Of course, all the trigger members 23a, 23a, 23bc, and 23c are arranged at positions near the workpiece W near the outer peripheral portions of the arc tubes 10, 10. The operation of the trigger members 23ab and 23bc disposed between the lamps is the same as that of the above (b). The opacity of the arc tubes 10, 10, 10 is remarkably generated on a very small portion (X ', X', X ') of the surface just opposite to the object W, but good light transmission is achieved in other portions of the arc tube. Thus, the object W can be directly irradiated with the radiated light from the lamps 1a, 1b, 1c, and the intended processing can be performed with extremely high efficiency.
[0027]
FIG. 7 is a diagram illustrating an embodiment of a light irradiation device including four lamps according to the present invention.
In FIG. 7A, the trigger member 24ab includes lamps 1a, 1b, 1c, and 1d, and is located at a position facing the workpiece W near the outer peripheral portion of the arc tube 10, 10 between the adjacent lamps. , 24bc, and 24cd. The same potential voltage is applied to these trigger members 24ab, 24bc, 24cd at the same timing. The trigger member 24ab acts on the lamps 1a and 1b, the trigger member 24bc acts on the lamps 1b and 1c, and the trigger member 24cd acts on the lamps 1c and 1d. In each of the arc tubes 10, 10 of the lamps 1a, 1d arranged on both outer sides, turbidity is likely to occur on the substantially semi-cylindrical side portions (X, X) opposite to the trigger members 24ab, 24cd, respectively. In the arc tubes of the lamps 1b and 1c, a remarkable portion is generated on a very small portion (X ', X') of the surface just opposite to the workpiece W. Also in this example, a portion having light transmissivity is formed at a portion of the arc tubes 10, 10, 10, 10 facing the processing object W, so that the processing object W can be irradiated with good light.
In FIG. 7B, a trigger member 24a having lamps 1a, 1b, 1c, and 1d and acting on the lamp 1a, a trigger member 24bc acting in common on the lamps 1b and 1c, and a lamp 1d are provided. This is an example in which a trigger member 24d that acts on the workpiece W is provided, and is disposed at a position facing the workpiece W in the vicinity of the outer peripheral portion of the arc tube 10, 10, 10, 10 of each of the lamps 1a, 1b, 1c, 1d. . Each arc tube 10, 10, 10, 10 of each of the lamps 1a, 1b, 1c, 1d has a substantially semi-cylindrical side surface portion (X, X) opposite to the surface on which the trigger members 24a, 24bc, 24d are arranged. , X, X), white turbidity is likely to occur, but since the object W has light transmittance, the object W can be irradiated with light for a long time.
FIG. 7C shows an example in which the trigger members 24a and 24d are respectively arranged outside the lamps 1a and 1d in addition to those shown in the above-mentioned item (a), and all the trigger members 24a, 24ab, 24bc, 24cd and 24d are examples arranged at positions facing the workpiece W in the vicinity of the outer peripheral portions of the arc tubes 10, 10, 10, 10. The operation of the trigger members 24ab, 24bc, 24cd disposed between the lamps is the same as in (a) above. The white turbidity of the arc tubes 10, 10, 10, 10 is remarkably generated at a very small portion (X ', X', X ', X') of the surface just opposite to the object W, but is good at other portions. High light transmittance. Therefore, the radiated light from the lamps 1a, 1b, 1c, and 1d can be directly radiated to the workpiece W, and the desired processing can be performed with extremely high efficiency.
[0028]
The embodiment of the present invention has been described above, but it is needless to say that the above can be appropriately changed. For example, a reflection mirror arranged above a lamp is not an essential component. Further, the trigger member is not limited to the one covered with the dielectric, but may be constituted only by the metal wire. Even in the case of covering with a dielectric material, the material of the dielectric material is not limited to glass but is appropriate.
[0029]
[Experimental example]
An experimental example was performed to demonstrate the effects of the present invention. FIGS. 8A to 8C are diagrams illustrating the light irradiation device used in the present experimental example.
According to the respective configurations shown in FIGS. 8A to 8C, light irradiation devices according to Examples 1 and 2 and Comparative Example were manufactured. Each light irradiation device has four lamps, and the specifications of the lamps are all the same.
FIG. 8A shows a state in which a trigger member is arranged in the same manner as that described above with reference to FIG.
FIG. 8 (B) shows a state in which a trigger member is arranged in the same manner as that described in FIG. 7 (C).
FIG. 8C shows a light irradiation apparatus according to the related art in which the trigger member is not disposed near the outer peripheral portion of the arc tube facing the workpiece. This device was used as a comparative example.
In FIG. 8, L1 and L2 are instantaneous spectrometers for detecting light having a wavelength of 200 to 800 nm from the lamps 1a to 1d. In this experiment, an instantaneous spectrometer (USR-30) manufactured by Ushio Inc. was used. did. The average ((L1 + L2) / 2) of the values measured by these two illuminometers L1 and L2 was calculated and used as the evaluation value.
[0030]
Hereinafter, each configuration of the flash lamp and the trigger member used in this experimental example, and driving conditions (lighting conditions) of the lamp and the trigger member will be described.
1. Flash lamp configuration
[Emission tube] Material: silica glass, outer diameter: 10.4 mm, wall thickness: 1.2 mm, total length: 200 mm,
[Enclosed gas] Gas type: Xenon, gas enclosed pressure: 60 kPa (450 Torr) (converted to 25 ° C),
[Electrode] Anode: tungsten, cathode: lanthanum (La) -tungsten alloy, distance between electrodes (light emission length): 160 mm
For each of the devices according to Examples 1 and 2 and the comparative example, flash lamps having the above specifications were prepared, and the lamp pitch was 12.4 mm (gap between arc tubes: 2.0 mm) and arranged side by side on the same surface.
2. Trigger member configuration
[Metal wire] Material: Tungsten, Wire diameter: φ1.0mm
[Dielectric] Material: silica glass, total length: 200, outer diameter: φ3.0 mm, wall thickness 0.7 mm
3. Drive conditions (lighting conditions)
[Lamp] Energy: 65 J / cm ² , Current: 2500 A, voltage: 2450 V (about 600 kW), pulse width: 300 μs
[Trigger member] Voltage: 10 kV
[0031]
FIG. 9 shows the results of the above experiment. In the figure, the illuminance characteristics of each light irradiation device are shown assuming that the illuminance in each device at the beginning of lighting is 1.0, the ordinate is the illuminance (relative value), and the abscissa is the number of times the lamp is lit. .
[0032]
In FIG. 9, the illuminances of the devices of Example 1, Example 2, and Comparative Example are 0.94, 0.97, and 0.86, respectively, after about 1000 times of lighting, and 0 after about 5000 times of lighting. 0.91, 0.74 and 0.5.
When the lighting was further continued, the illuminance of each device became 0.67, 0.9, and 0.39 after lighting about 10,000 times, respectively.
When the number of times of lighting exceeded 10,000 times, in Example 1, the luminous tube of the lamp became cloudy, but the decrease in illuminance caused by the turbidity was relatively slow, and a sufficient improvement was obtained as compared with the conventional product. In the device according to the second embodiment, the portion of the arc tube facing the object to be processed did not cause white turbidity, and the illuminance was maintained at 0.9 or more. In the device according to the second embodiment, since the inner wall of the arc tube on the mirror member side becomes clouded compared to the initial stage of lighting, the reflected light from the mirror member hardly reaches the object to be processed, but the other radiation light is Since the object can be satisfactorily reached, an extremely good illuminance maintaining characteristic can be obtained.
In the conventional device according to the comparative example, a noticeable decrease in illuminance was observed as early as possible. In the device according to the comparative example, the lamp emits light near the trigger member, but the light from the place is reflected by the mirror member but is blocked by the cloudy portion of the arc tube, so that the object to be processed is eventually irradiated. You can't do that. Therefore, when the lamps are repeatedly turned on, it is impossible to irradiate not only the light directly irradiating the object to be processed but also the reflected light.
In the devices according to the first and second embodiments, even if the number of times of lighting of the lamp is repeated, since the light-transmitting portion is formed in the portion of the arc tube facing the object, the influence of white turbidity can be avoided. It is possible to suppress a decrease in illuminance.
[0033]
【The invention's effect】
As described above, according to the present invention, in the light irradiation device used for the annealing process, even if the flash lamp is turned on with a short pulse, the trigger member remains in the vicinity of the outer peripheral portion of the arc tube. Because it is located at the position facing the object, it is possible to suppress cloudiness in the portion of the arc tube facing the object to be processed, repeat the lighting of the lamp, even if the arc tube becomes significantly cloudy, Can be applied to the surface of the object with high illuminance. Therefore, the lamp replacement time can be delayed as compared with the conventional product, so that the lamp replacement frequency can be reduced and an industrially usable light irradiation device can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view cut along a plane passing through an axis of a lamp for explaining a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of the lamp according to the first embodiment of the present invention, taken in a direction perpendicular to the axis of the lamp.
FIG. 3 is a diagram illustrating a state in which white turbidity of a lamp occurs.
FIG. 4 is a view illustrating an embodiment of a light irradiation device including one lamp according to the present invention.
FIG. 5 is a diagram illustrating an embodiment of a light irradiation device including two lamps according to the present invention.
FIG. 6 is a diagram illustrating an embodiment of a light irradiation device including three lamps according to the present invention.
FIG. 7 is a diagram illustrating an embodiment of a light irradiation device including four lamps according to the present invention.
FIG. 8 is a diagram illustrating a light irradiation device used in an experimental example.
FIG. 9 is a diagram showing characteristics of the number of times of lamp lighting and the illuminance maintenance ratio, showing the results of an experiment.
[Explanation of symbols]
1 Flash lamp
10 arc tube
11 Cathode (electrode)
11 'anode (electrode)
12,12 'Lead rod
2 Trigger member
201 glass tube
201a one end
202 metal wire
203 feeder
1a, 1b, 1c, 1d Flash lamp
21, 21 'trigger member
22a, 22ab, 22c Trigger member
23a, 23ab, 23bc, 23c Trigger member
24a, 24ab, 24bc, 24cd, 24d Trigger member
3 Mirror member
S stage
W Workpiece

Claims (1)

A flash lamp having an arc tube made of silica glass, a trigger member arranged in the tube axis direction of the lamp, and a power supply for supplying power to the lamp, the irradiation energy of the flash lamp being 65 kW / Cm ² or more, a pulse width of 300 μs or less, a light irradiation device for irradiating the object with light from the lamp,
The light irradiation device, wherein the trigger member is disposed at a position facing an object near an outer peripheral portion of the arc tube.

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