JP2004111670A - Laser device, laser irradiating method, semiconductor device, or manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize energy of a laser beam. <P>SOLUTION: An optical system samples a part of the laser beam oscillated from an oscillator. A generating means uses a part of laser beam to generate the electric signal, containing the fluctuation in the energy of laser beam as data. A flow-rate adjusting means adjusts the flow rate of the gas in a discharge tube provided to the oscillator. A signal-processing part acquires the state of fluctuation of the laser beam energy, by applying an electrical signal with signal processing, and based on the acquired energy state, controls the flow-rate adjusting means to suppress fluctuations in the laser beam energy, for adjusting the flow rate of the gas. <P>COPYRIGHT: (C)2004,JPO

Description

【００４１】
高速フーリエ変換による周波数分析が行なわれると、最もピークの高い周波数とそのピークの高さを得ることができる。該周波数は、レーザ光が有するエネルギーの変動（定周期変動）に対応している。以下、該周波数を定周期周波数と呼ぶ。またそのピークの相対的な高さは、定周期変動の振幅に対応している。
【００４２】
図３に、図２に示したデータに高速フーリエ変換を施した後のデータを示す。図３（Ａ）は図２（Ａ）に、図３（Ｂ）は図２（Ｂ）に、図３（Ｃ）は図２（Ｃ）に、図３（Ｄ）は図２（Ｄ）に、図３（Ｅ）は図２（Ｅ）に、それぞれ対応している。横軸は周波数（Ｈｚ）を示し、縦軸は振幅を示している。
【００４３】
図３（Ａ）〜図３（Ｅ）のそれぞれのグラフにおいて、１つだけ最も高いピークが観測されている。具体的に図３（Ａ）では４．７８Ｈｚ、図３（Ｂ）では４．７８Ｈｚ、図３（Ｃ）では５．２２７５Ｈｚ、図３（Ｄ）では１５．２１Ｈｚ、図３（Ｅ）では２４．８Ｈｚにおいて最も高いピークが観測されている。該ピークの周波数が定周期周波数に相当する。
【００４４】
ところで放電管内には、ガスを励起させる機能を有する主放電管が設けられている。レーザ光のエネルギーは、主放電管の陽極と陰極の間における、ガスのモル濃度に左右される。つまりガスの温度が一定だと仮定すると、主放電管内のガスの圧力に左右されるということになる。放電管１０８内のガスの圧力は基本的には一定であることが望ましいが、実際には放電管１０８内を循環しているガスの流量の変動に連動して変化する。本発明では、圧電素子１０６の振動で放電管１０８内のガスの流量の変動を調整することで、レーザ光のエネルギーを制御する。
【００４５】
具体的に本発明では、圧電素子１０６がレーザ光の定周期周波数と同じ周波数でもって振動するように、信号処理部１０４において圧電素子ドライバ１０５を制御する。本実施の形態では、圧電素子１０６は放電管１０８内に設けられており、その振動によって放電管１０８内のガスの流量を調整することができる。
【００４６】
図１（Ｂ）に放電管１０８内の断面図を示す。放電管１０８内にはレーザ媒質として用いるガスが充填されている。該ガスは、放電管１０８内を送風機１１０により循環している。送風機１１０から送られたガスは、主放電管１１１の陽極１１２と陰極１１３の間を通過した後、熱交換器１１４を通って、再び送風機１１０に戻るように循環している。熱交換器１１４は主放電管１１１で発生した熱を放熱させ、放電管１０８内のガスの温度を一定に保つ機能を有している。
【００４７】
なお本実施の形態では、主放電管１１１の上流側と下流側に予備電離電極１１５を設け、紫外線で予備電離させる方式（紫外線予備電離方式）を用いているが、本発明のレーザ装置は紫外線予備電離方式に限定されず、例えばコロナ予備電離方式、Ｘ線予備電離方式などその他の予備電離方式を用いていても良いので、予備電離電極１１５は必ずしも設ける必要はない。
【００４８】
圧電素子１０６は、送風機１１０の下流側で、なおかつ主放電管１１１の上流側に設けるのが望ましい。圧電素子ドライバ１０５から印加される電圧に従って、圧電素子１０６は振動する。圧電素子１０６が振動することで、送風機１１０によって起こるガスの流れに、圧電素子１０６の振動によって起こるガスの流れが加算され、結果的に主放電管１１１に流れるガスの流量が調節される。
【００４９】
なお本実施の形態では、圧電素子１０６自身でガスの流れを起こしているが、圧電素子１０６の振動を圧電素子以外のものに伝達させる事で、間接的にガスの流れを起こすようにしても良い。この場合、圧電素子は必ずしも放電管１０８の内部に設ける必要がない。
【００５０】
圧電素子１０６の振動のみによって起こされるガスの流量は、定周期振動と同じ周波数で、なおかつ逆の位相で変動するように調整する。
【００５１】
なお本実施の形態では、ガス用センサ１０７を用いて、主放電管１１１近辺のガス圧の変動の状態をデータとして含む電気信号を生成し、信号処理部１０４に入力する。そして、信号処理部１０４において該電気信号にＦＦＴ等の信号処理を施すことで、主放電管１１１近辺のガスの圧力の変動の状態を把握し、該変動の高低差を縮めるように、圧電素子ドライバ１０５を用いて圧電素子１０６の振動の振幅、位相を調整する。ガス用センサ１０７は、主放電管１１１の上流側で、なおかつ圧電素子１０６の下流側であることが望ましい。
【００５２】
図４（Ａ）に、高速フーリエ変換から算出された、レーザ光のエネルギーの定周期変動の波形を示す。定周期周波数を１／Ｔとすると、定周期変動の周期はＴで表される。Ａはレーザ光の、定周期変動の振幅を表している。図４（Ａ）に示した定周期変動の波形から生成される、圧電素子１０６の振動のみによって起こされるガスの流量の変動の波形を、図４（Ｂ）に示す。圧電素子１０６の振動のみによって起こされるガスの流量の変動の波形は、定周期変動の波形と同じ周期Ｔを有しており、その位相はＴ／２だけずれている。なおＢは流量の振幅を示している。
【００５３】
圧電素子１０６の振動のみによって起こされるガスの流量の振幅Ｂは、該流量が最大値を有するときに得られるレーザ光のエネルギーと、該流量が最小値を有するときに得られるレーザ光のエネルギーとがより近くなるように設定する。
【００５４】
圧電素子１０６の振動によってエネルギーが調整されたレーザ光は、発振器１００から出射される。上記補正手段によって、本発明のレーザ装置において、発振器１００から出力されるレーザ光のエネルギーの変動を抑えることができる。より具体的には、レーザ光のエネルギーの定周期変動を抑えることができる。
【００５５】
次に、位相の制御について詳しく説明する。
【００５６】
図５（Ａ）に、補正前のレーザ光の波形を破線で、補正後のレーザ光の波形を実線で示す。図５（Ａ）では、エネルギーの定周期変動の位相と、圧電素子１０６の振動のみによって起こされるガスの流量の変動の位相とが丁度半周期分だけずれている場合を示している。ただし図５（Ａ）では、定周期変動の波形を分かり易くするために、信号処理によって確認された定周期変動の波形のみを示す。図５（Ａ）において、補正前のレーザ光の波形と、補正後のレーザ光の波形とが、同じ位相を有している。よって、圧電素子１０６の振動のみによって起こされるガスの流量の変動の位相は、レーザ光の定周期変動の位相と丁度Ｔ／２ずれてるように設定されていると考えられる。そして、レーザ光の振幅Ａ’がより小さくなるように、流量の振幅を調整することで、レーザ光のエネルギーの安定性をより高めることができる。
【００５７】
次に図５（Ｂ）に、位相のずれがＴ／２ではない場合の、補正前のレーザ光の波形を破線で、補正後のレーザ光の波形を実線で示す。ただし図５（Ａ）と同様に、図５（Ｂ）でも、定周期変動の波形を分かり易くするために、信号処理によって確認された定周期変動の波形のみを示す。図５（Ｂ）において、補正前のレーザ光の波形と補正後のレーザ光の波形とが、同じ位相を有していない。よって、圧電素子１０６の振動のみによって起こされるガスの流量の変動の位相と、レーザ光の定周期変動の位相との差が、Ｔ／２ではないことが予測される。この場合、信号処理部において位相の調整を別途行なうことで、レーザ光の定周期変動を抑えるようにする。
【００５８】
なお、振幅、位相の調整は、本実施の形態で示す方法に限定されない。振幅と位相を、発振器から出力されるレーザ光のエネルギーの定周期変動の最大値と最小値がより近づくように、レーザ光をモニターしながら調整するようにしても良い。この場合、必ずしもガス用センサ１０７を用いて、主放電管１１１近辺のガス圧の変動をモニターする必要はない。ガス圧以外の要因によってエネルギーが変動している場合もあるので位相差は必ずしもＴ／２であるとは限らない。よって、レーザ光をモニターしながら調整する方が適切な位相差を模索しやすく、ガス圧をモニターするよりも、より確実にレーザ光の変動を抑えることができる。
【００５９】
なお、補正後のレーザ光のエネルギーまたは主放電管１１１近辺のガス圧をモニターすることで位相を調整することが可能であるが、位相の調整はこの構成に限定されない。例えば、発振器におけるレーザ光の発振と同期した信号を基準として、圧電素子１０６の振動の位相と、レーザ光のエネルギーの位相とを合わせるようにしても良い。具体的には、周波数及びレーザ光の変動との位相差が予め分かっている信号（基準信号）と、レーザ光の定周期周波数とから、その位相差を算出することで、位相を合わせることができる。
【００６０】
また、上記補正手段に、信号処理部で定められた圧電素子の振動の周波数及び振幅に関する情報をメモリ等に記憶しておき、次回改めて圧電素子の振動の周波数及び振幅を調整する手間を省くようにしても良い。
【００６１】
なお、本実施の形態では流量調整手段として圧電素子を用いているが、本発明はこれに限定されない。放電管内におけるガスの流量を調整することができる手段であるならば、本発明において流量調整手段として用いることが可能である。例えば、放電管内にガスを供給する電磁弁と、放電管内のガスを排気する電磁弁とを設けておき、これら２つの電磁弁の開放によってガスの流量を調整するようにしても良い。
【００６２】
また、周期性のないエネルギーの変動であっても、モニターした結果を即レーザ光にフィードバックできるような速度でガスの流量を調整できるのであれば、周期性のない変動でも抑えることができる。
【００６３】
【実施例】
以下、本発明の実施例について説明する。
【００６４】
（実施例１）
レーザ光のエネルギーの定周期変動は、発振器の発振周波数によって異なる。本実施例では、エキシマレーザの発振器から発せられるレーザ光の発振周波数と、定周期変動の周波数の関係について説明する。
【００６５】
図６に、レーザ光の発振周波数（Ｈｚ）と、フーリエ変換によって得られる最も高いピークの周波数（Ｈｚ）の関係を示す。横軸が発振周波数（Ｈｚ）であり、縦軸がフーリエ変換後のピーク位置（Ｈｚ）を示している。なお各測定は測定した日にちが異なっているが、発振周波数以外の測定条件は同じである。
【００６６】
フーリエ変換によって得られる最も高いピークの周波数は、レーザ光のエネルギーの定周期変動の周波数を意味している。定周期変動の周波数は、段階的に増減を繰り返している。具体的には、定周期変動の周波数は、発振周波数が約３Ｈｚ、１２Ｈｚ、２５Ｈｚのときに極小値を有し、約３Ｈｚ、１０Ｈｚ、２２Ｈｚのときに極大値を有している。そして、発振周波数が約２５Ｈｚを超えた後は、増加し続けている。
【００６７】
図６に示したように、用いるレーザ光の発振周波数と定周期変動の周波数との関係を予め調べることで、実際に被処理物へのレーザ光の照射を行なう際に最適な条件を模索するのに役立てることができる。例えば、定周期変動の周波数が高くなる条件を選ぶことで、定周期変動によって発生する半導体膜の横縞の間隔を視認されない程度に短くすることができる。また逆に、定周期変動の周波数が低くなる条件を選ぶことで、定周期変動によって発生する半導体膜の横縞の間隔を長くし、照射領域内に横縞が現れないようにすることも可能である。
【００６８】
図６のデータをもとに、半導体膜の結晶化に用いる標準的なレーザ光の照射条件（発振周波数が３０Ｈｚ、スキャン速度１．０ｍｍ／ｓｅｃ）のときと同じショット数（約１３ショット）が得られるようにレーザ光を照射したときの、各発振周波数において生じると予測される横縞の間隔を計算する。具体的には、以下の式２から計算する。
【００６９】
【式２】

ｄ（ω）：横縞の間隔周期
ω：発振周波数
ω_０：標準的な照射条件における発振周波数（＝３０Ｈｚ）
ν_０：標準的な照射条件における基板スキャン速度（＝１．０ｍｍ／ｓｅｃ）
Ｔ（ω）：定周期変動の周波数
【００７０】
式２から計算された、発振周波数に対する横縞の周期の関係を図７に示す。発振周波数ω＝２５Ｈｚに特徴的なピークが現れ、２５Ｈｚでの横縞は約３．９ｍｍ間隔であると予測された。それ以外の発振周波数では、約６０〜約５００μｍ間隔となった。なお、２５Ｈｚにおける基板スキャン速度の想定値は、ショット数を標準条件（３０Ｈｚ、１．０ｍｍ／ｓｅｃ）に合わせこむと、０．８３３ｍｍ／ｓｅｃとなる。
【００７１】
（実施例２）
本実施例では、実施の形態に示した本発明のレーザ装置の一実施例について説明する。
【００７２】
図８に本実施例のレーザ装置の構成を示す。発振器１５００から発振されたレーザ光は、光学系１５０１においてその一部がサンプリングされる。サンプリングされたレーザ光はレーザ光用センサ１５０２に入射する。
【００７３】
一方、サンプリングされたレーザ光以外の残りのレーザ光は、ビームエキスパンダー１５０３に入射する。なお本実施例では、発振器１５００とビームエキスパンダー１５０３の間の光路中に、レーザ光を遮るシャッター１５０４が設けられているが、必ずしも設ける必要はない。
【００７４】
そして、ビームエキスパンダー１５０３によって、入射してきたレーザ光の広がりを抑え、なおかつ、ビームスポットの大きさを調整することができる。
【００７５】
ビームエキスパンダー１５０３から出射したレーザ光は、ビームホモジナイザー１５０５において、ビームスポットの形状が矩形状、楕円状または線状になるように集光される。そして、該集光されたレーザ光は、ミラー１５０６において反射し、レンズ１５０７に入射する。入射したレーザ光はレンズ１５０７によって再び集光され、半導体膜が成膜された基板１５０８に照射される。本実施例ではレンズ１５０７としてシリンドリカルレンズを用いた。
【００７６】
基板１５０８はステージ１５０９上に載置されており、該ステージ１５０９は３つの位置制御手段（ドライバ）１５１０〜１５１２によってその位置が制御されている。具体的には、φ方向位置制御手段１５１０により、水平面内においてステージ１５０９を回転させることができる。また、Ｘ方向位置制御手段１５１１により、水平面内においてステージ１５０９をＸ方向に移動させることができる。また、Ｙ方向位置制御手段１５１２により、水平面内においてステージ１５０９をＹ方向に移動させることができる。各位置制御手段の動作は、中央処理装置１５１９において制御されている。
【００７７】
上述した３つの位置制御手段の動作を制御することで、基板１５０８においてレーザ光が照射される位置を制御することができる。
【００７８】
一方、レーザ光用センサ１５０２では、サンプリングされたレーザ光を電気信号に変換し、信号処理部１５１３に入力する。該電気信号は、レーザ光のエネルギーの変動の状態をデータとして有している。そして、信号処理部１５１３における信号処理によって該データの解析が行なわれ、レーザ光のエネルギーの変動の状態が把握される。
【００７９】
また発振器１５００から、レーザ光の発信に同期した基準信号が信号処理部１５１３に入力される。信号処理部１５１３では、把握された変動の状態、基準信号等を用いて、発振器１５００内に設けられた放電管におけるガスの流量を調整する。
【００８０】
なお、本発明の補正手段には、光学系１５０１、センサ１５０２、信号処理部１５１３と、放電管内に設けられたガスの流量を調整する手段が含まれる。
【００８１】
また本実施例のように、ＣＣＤ等の受光素子を用いたモニター１５１４を設け、基板の位置を正確に把握できるようにしても良い。
【００８２】
なおレーザ光のスキャンの方法は、被処理物を固定してレーザ光の照射位置を移動させる照射系移動型と、レーザ光の照射位置は固定して被処理物を移動させる被処理物移動型と、上記２つの方法を組み合わせた方法とがある。
【００８３】
図８に示したレーザ装置は、被処理物移動型であるが、本発明はこれに限定されない。照射系移動型のレーザ装置や、被処理物移動型と照射系移動型を組み合わせたレーザ装置にも用いることができる。レーザ光の照射は、半導体膜におけるレーザ光のビームスポットが、走査方向において重なるように照射する。
【００８４】
本実施例は、実施例１と組み合わせて実施することが可能である。
【００８５】
【発明の効果】
本発明では、レーザ光のエネルギーの変動をモニターすることで、レーザ光のエネルギーの制御を精密に行なうことができるので、従来のガス圧をモニターする方法よりも確実にレーザ光の変動を打ち消すことができ、より安定なエネルギーを有するレーザ光を得ることができる。より具体的には、周期的に発生するレーザ光のエネルギーの変動を抑えることができる。
【図面の簡単な説明】
【図１】補正手段の構成を示すブロック図。
【図２】発振周波数ごとのエネルギーの実測値を示すグラフ。
【図３】発振周波数ごとのエネルギーの実測値のＦＦＴ後のデータを示すグラフ。
【図４】エネルギーの定周期変動と、流量の変動を示す図。
【図５】レーザ光のエネルギーの変動を示す図。
【図６】発振周波数と、フーリエ変換後の周波数のピーク位置の関係を示すグラフ。
【図７】ショット数を標準に合わせたときの、発振周波数と横縞の間隔との関係を示す図。
【図８】本発明のレーザ装置の構成を示す図。
【図９】時間に対するレーザ光のエネルギーの値と、ＦＦＴ後のデータ。
【図１０】エキシマレーザのレーザ光を照射し、結晶化を行なった半導体膜を上面からみた写真。
【図１１】結晶化後の半導体膜を上面からみた写真と、レーザ光のエネルギーの値を濃淡で示した図。
【図１２】結晶化後の半導体膜を上面からみた写真と、該半導体膜を用いて形成された発光装置の画素部の写真。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a laser device or a laser irradiation method, and particularly to a laser device or a laser irradiation method having a mechanism for stabilizing the energy of an output laser beam. In addition, the present invention relates to a method for manufacturing a semiconductor device including a step of crystallizing a semiconductor film using the laser device or the laser irradiation method, and a semiconductor device.
[0002]
[Prior art]
Lasers are classified into gas lasers and solid-state lasers according to the laser medium, and the types are various. Lasers have different wavelengths, energies, pulse characteristics, and the like of the obtained laser light depending on the laser medium, and applications for the properties of the laser light have been searched for. Among various lasers, YAG laser, CO ₂ Lasers, excimer lasers, and the like are used in most industrial laser devices.
[0003]
Among them, an excimer laser, which is a gas laser, is a powerful ultraviolet ray, and its wavelength is as short as 0.193 μm for ArF and 0.351 μm for XeF, and is excellent in condensing property. Therefore, it is suitable for fields requiring ultra-fine processing at the μm level, as represented by semiconductor manufacturing including mask molding and the like, in addition to general component processing.
[0004]
However, excimer laser and CO ₂ In general, a gas laser typified by a laser tends to fluctuate in pressure of a gas serving as a laser medium in an oscillator. Fluctuation is likely to occur. Therefore, there is a disadvantage that the energy of the laser beam output from the oscillator is hardly kept stable, and it is difficult to uniformly process the object.
[0005]
Therefore, conventionally, the fluctuation of the pressure of the laser medium in the discharge tube is detected so as to stabilize the energy of the output laser light, and the fluctuation of the pressure is generated so as to cancel the fluctuation. A method for suppressing fluctuations in pressure or flow rate has been proposed (for example, see Patent Document 1).
[0006]
[Patent Document 1]
JP-A-07-038180 (page 2-3, FIG. 3)
[0007]
In Patent Literature 1, a pressure change caused by a change in the flow rate of a gas as a laser medium is detected by a pressure sensor provided in a gas supply duct, and is input to a feedback control unit as a detection signal. The feedback control unit inverts the phase of the detection signal. Then, the waveform generator performs a frequency analysis by a fast Fourier transform (FFT) on the detection signal having the inverted phase to obtain a waveform signal. Then, after amplifying the waveform signal, it is input to the vibrator. The vibrator generates a pressure fluctuation having the same amplitude as the pressure fluctuation detected by the pressure sensor and an opposite phase according to the input amplified waveform signal, thereby canceling the fluctuation of the pressure of the laser medium.
[0008]
[Problems to be solved by the invention]
However, the fluctuation of the energy of the laser beam does not always correspond one-to-one to the fluctuation of the pressure of the laser medium in the discharge tube. For example, in addition to the pressure fluctuation of the gas in the discharge tube, it may be affected by noise generated by a thyratron provided in an excimer laser excitation circuit. In the method described in Patent Document 1, since the correction is performed based on the gas pressure fluctuation in the discharge tube, it is difficult to suppress the energy fluctuation due to factors other than the gas pressure, so that the accuracy is poor. Therefore, there is a limit in suppressing the fluctuation of the energy of the laser beam.
[0009]
Originally, an excimer laser is a CO2 laser described in Patent Document 1 described above. ₂ The fluctuation of the energy of the output laser light is smaller than that of the laser. However, excimer lasers are widely used for micromachining because of their excellent light-collecting properties, so CO2 ₂ A higher level of stability is required compared to lasers. Therefore, in the case of using the vibrator to cancel the fluctuation of the pressure of the laser medium as in the above method, in the case of an excimer laser, it is difficult to stabilize the energy of the output laser light to a sufficient level.
[0010]
If the output of the laser beam is not stable, it is difficult to uniformly process the object. For example, in crystallization of a semiconductor film using laser light irradiation, a slight change in energy of about 10% is considered to cause a difference in crystallinity.
[0011]
Therefore, the present inventors sampled a part of the laser light output from the pulse oscillation excimer laser, and observed the energy fluctuation. FIG. 9A shows the value of the energy of the sampled laser light with respect to time. The oscillation frequency of the excimer laser is 25 Hz.
[0012]
FIG. 9B shows data obtained by performing FFT on the data shown in FIG. 9A. In FIG. 9B, the horizontal axis represents frequency, and the vertical axis represents amplitude. In the data subjected to FFT, a remarkably high peak was observed at a frequency of 0.24583 Hz. This frequency corresponds to the frequency of the periodic energy fluctuation among the laser light energy fluctuations observed in FIG.
[0013]
Note that in FIG. 9A, during the period from the start of measurement to 20 sec, the energy fluctuation is larger than the other due to the transient response of the detector of the measuring apparatus. The data after FFT is the same.
[0014]
Assuming that the semiconductor film is crystallized by scanning the laser beam having the above-described energy fluctuation at 0.8 mm / sec, the energy density is highest at an interval of 0.8 / 0.24583 ≒ 3.3 mm. This is a calculation in which laser light is applied to the semiconductor film.
[0015]
FIG. 10 shows a photograph of the semiconductor film actually crystallized by excimer laser irradiation and viewed from above. The laser beam used was a pulsed excimer laser, and the irradiation was performed at an oscillation frequency of 25 Hz and a scan speed of 0.8 mm / sec. In the semiconductor film shown in FIG. 10, a plurality of horizontal stripes caused by a difference in crystallinity are visually recognized in a direction perpendicular to a scan direction indicated by an arrow. Since the interval between the plurality of horizontal stripes is 3.4 mm, which substantially coincides with the value 3.3 mm obtained by the above-mentioned calculation, the horizontal stripes are caused by the periodic fluctuation of energy. Can be heard.
[0016]
Further, FIG. 11 shows a photograph of the semiconductor film after crystallization viewed from above and a part of the laser light output from the pulse oscillation excimer laser, and the energy value can be expressed in 15 gradations. Are shown side by side. Note that the oscillation frequency of the laser beam in FIG. 11 is 30 Hz, the scan speed is 1.0 mm / sec, and the scan direction is as indicated by the arrow. It should be noted that in the portion where the intensity of the energy is indicated by shading, there is a portion that looks white continuously at the start of scanning, which is due to the transient response of the measuring instrument.
[0017]
As can be seen from FIG. 11, a plurality of horizontal stripes are generated in the semiconductor film after crystallization in a direction perpendicular to the scanning direction due to a difference in crystallinity. In addition, a plurality of horizontal stripes due to fluctuations in the energy of the sampled periodic cycle are formed by shading indicating the strength of the energy. These two horizontal stripes have the same interval, and therefore, a plurality of horizontal stripes observed in the semiconductor film and caused by a difference in crystallinity are caused by periodic energy fluctuations. As can be seen from FIG.
[0018]
As described above, when a thin film transistor (TFT) is manufactured using a semiconductor film having a variation in crystallinity, the on-current varies depending on the location of the semiconductor film. In a light-emitting device in which the TFT is used as a transistor for controlling current to a light-emitting element, a problem occurs in that a high-luminance region and a low-luminance region are visually recognized as stripes.
[0019]
FIG. 12 shows a photograph of an upper surface of a semiconductor film after crystallization by laser light and a photograph of an upper surface in a state where a light-emitting device using the semiconductor film displays all white. Specifically, in the light-emitting device illustrated in FIG. 12, a pixel including a TFT formed using a semiconductor film after crystallization and a light-emitting element in which current supplied by the TFT is controlled is provided in a pixel portion. A plurality is provided. Note that the light-emitting element uses an electroluminescent material from which luminescence generated by applying an electric field can be obtained.
[0020]
In FIG. 12, a semiconductor film 2000 after crystallization and pixel portions 2001, 2002, and 2003 of the light emitting device are overlapped with each other at a position corresponding to the semiconductor film. Note that the pixel portions 2001, 2002, and 2003 of the light emitting device have different gray scales to be displayed.
[0021]
As shown in FIG. 12, a horizontal stripe is visually recognized in a part 2001 of the pixel portion, though it is difficult to be visually recognized in a part of the pixel portion 2002 or 2003 of the light emitting device. The horizontal stripes coincide with the horizontal stripes of the semiconductor film, and it can be confirmed that the horizontal stripes are displayed on the display of the light emitting device due to a variation in the energy of the laser light.
[0022]
In view of the above problems, an object of the present invention is to provide a laser device, a laser irradiation method, and a method for manufacturing a semiconductor device, which can further stabilize the energy of laser light. Another object is to provide a semiconductor device manufactured using the method for manufacturing a semiconductor device.
[0023]
[Means for Solving the Problems]
The present inventors can monitor the laser light output from the oscillator directly, instead of monitoring the pressure of the laser medium in the discharge tube, to more accurately grasp the state of the energy fluctuation of the laser light. We thought that it would be possible to stabilize the energy of the obtained laser beam.
[0024]
According to the present invention, a part of a laser beam output from an oscillator is sampled to grasp a change in energy of the laser beam. Then, the control is performed so as to suppress the fluctuation of the gas pressure in the discharge tube using the grasped data of the fluctuation of the energy.
[0025]
Specifically, the correction means of the laser device of the present invention includes:
(1) Flow rate adjusting means for adjusting the flow rate of the laser medium (gas) in the discharge tube
(2) Means for sampling a part of the laser light oscillated from the oscillator (optical system)
{Circle around (3)} A means (sensor) for using a part of the laser light sampled by the optical system to generate an electric signal including data of a change in energy of the laser light as data.
(5) By performing signal processing on the electric signal, the state of the fluctuation of the energy of the laser light is grasped, and based on the grasped state of the energy, the flow rate is controlled by a driver so as to suppress the fluctuation of the energy of the laser light. Means for controlling the adjusting means to adjust the gas flow rate (signal processing unit)
have.
[0026]
In addition to the above configuration, (6) a means (driver) for controlling the operation of the flow rate adjusting means may be included in the correcting means of the present invention.
[0027]
Further, the correction means of the laser device of the present invention includes:
(1) Flow rate adjusting means for adjusting the flow rate of the laser medium (gas) in the discharge tube
(2) Means for sampling a part of the laser light oscillated from the oscillator (optical system)
{Circle around (3)} A means for generating a first electric signal including a change in energy of the laser light as data using a part of the laser light sampled by the optical system (laser light sensor)
{Circle around (4)} Means for measuring the pressure of gas in the discharge tube and generating a second electric signal including the value of the pressure as data (gas sensor)
{Circle around (5)} By performing signal processing on the first electric signal, the state of fluctuation of the energy of the laser beam is grasped, and by performing signal processing on the second electric signal, the gas pressure at a specific location in the discharge tube can be reduced. Means for grasping and controlling the driver based on the grasped energy state and gas pressure using a flow rate adjusting means so as to reduce the height difference of the gas flow rate (signal processing unit)
have.
[0028]
In addition to the above configuration, (6) a means (driver) for controlling the operation of the flow rate adjusting means may be included in the correcting means of the present invention.
[0029]
As in the above configuration, by monitoring the change in the energy of the laser light, the state of the energy of the laser light can be grasped more accurately. The fluctuation can be canceled, and a laser beam having more stable energy can be obtained. More specifically, it is possible to suppress the fluctuation of the energy of the laser light that occurs periodically.
[0030]
In addition, by using the above laser device for crystallization of a semiconductor film, the crystallinity of the semiconductor film can be made more uniform. Note that the method for manufacturing a semiconductor device of the present invention can be used for a method for manufacturing an integrated circuit or a semiconductor display device. In particular, a liquid crystal display device, a light emitting device having a light emitting element typified by an organic light emitting element in each pixel, a semiconductor display device such as a DMD (Digital Micromirror Device), a PDP (Plasma Display Panel), and a FED (Field Emission Display). When used for a semiconductor element such as a transistor provided in a pixel portion, horizontal stripes due to energy distribution of laser light applied to the pixel portion can be suppressed from being visually recognized.
[0031]
Note that the present invention uses an excimer laser or a CO ₂ The present invention can be applied not only to lasers but also to other gas lasers, and can be applied not only to gas lasers but also to solid-state lasers. In addition, the oscillation method is not limited to pulse oscillation, and can be applied to a continuous oscillation laser device.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1A is a block diagram of the correction unit 101 according to the present embodiment. 1A includes an optical system 102, a laser light sensor 103, a signal processing unit 104, a piezoelectric element driver 105, a piezoelectric element 106, and a gas sensor 107. The piezoelectric element 106 and the gas sensor 107 are provided in a discharge tube 108 included in the oscillator 100.
[0033]
The discharge tube 108 is filled with a gas that is a laser medium, and photons obtained by exciting the laser medium in the discharge tube 108 provided in the oscillator are generated by an optical resonator also provided in the oscillator. By being resonated, laser light is obtained.
[0034]
In the present invention, a part of the laser light oscillated from the oscillator 100 is sampled using the optical system 102 and made incident on the laser light sensor 103. The laser light sensor 103 converts a part of the incident laser light into an electric signal and inputs the electric signal to the signal processing unit 104.
[0035]
The laser light sensor 103 may use any photoelectric conversion element as long as it can generate an electric signal having a change in energy of laser light as data. For example, a photodiode, a phototransistor, a charge coupled device (CCD), or the like can be used.
[0036]
FIG. 2 is a graph showing a change in energy of the sampled laser light. A pulse oscillation excimer laser is used. The horizontal axis indicates time (sec), and the vertical axis indicates the relative ratio (%) of energy at each measurement point to the average value of energy of all measurements. .
[0037]
The oscillation frequency of the laser light is 10 Hz in FIG. 2A, 20 Hz in FIG. 2B, 30 Hz in FIG. 2C, 40 Hz in FIG. 2D, and 50 Hz in FIG.
[0038]
In the signal processing unit 104, signal processing of the electric signal generated in the laser light sensor 103 is performed, and periodic fluctuations among the fluctuations in the energy of the laser light are analyzed. The signal processing is not limited to the fast Fourier transform, and various signal processings can be used. The minimum required is the frequency of the periodic fluctuation among the fluctuations of the energy of the laser beam. Here, a case where signal processing is performed using fast Fourier transform will be described.
[0039]
The Fast Fourier Transform is described in WaveMetrics, Inc. Calculation program software IGOR
This was performed according to the following formula 1 using Pro.
[0040]
(Equation 1)

[0041]
When the frequency analysis by the fast Fourier transform is performed, the frequency having the highest peak and the height of the peak can be obtained. The frequency corresponds to a change in energy of the laser beam (a periodic change). Hereinafter, the frequency is referred to as a periodic frequency. The relative height of the peak corresponds to the amplitude of the periodic fluctuation.
[0042]
FIG. 3 shows data obtained by performing the fast Fourier transform on the data shown in FIG. 3 (A) is shown in FIG. 2 (A), FIG. 3 (B) is shown in FIG. 2 (B), FIG. 3 (C) is shown in FIG. 2 (C), and FIG. 3 (D) is shown in FIG. FIG. 3E corresponds to FIG. 2E, respectively. The horizontal axis indicates frequency (Hz), and the vertical axis indicates amplitude.
[0043]
In each graph of FIGS. 3A to 3E, only one highest peak is observed. More specifically, 4.78 Hz in FIG. 3A, 4.78 Hz in FIG. 3B, 5.2275 Hz in FIG. 3C, 15.21 Hz in FIG. 3D, and 24 in FIG. The highest peak is observed at 0.8 Hz. The frequency of the peak corresponds to the periodic frequency.
[0044]
Incidentally, a main discharge tube having a function of exciting a gas is provided in the discharge tube. The energy of the laser light depends on the molar concentration of the gas between the anode and cathode of the main discharge tube. That is, assuming that the gas temperature is constant, it depends on the gas pressure in the main discharge tube. It is desirable that the pressure of the gas in the discharge tube 108 is basically constant. However, in practice, the pressure changes in accordance with the fluctuation of the flow rate of the gas circulating in the discharge tube 108. In the present invention, the energy of the laser beam is controlled by adjusting the fluctuation of the flow rate of the gas in the discharge tube 108 by the vibration of the piezoelectric element 106.
[0045]
Specifically, in the present invention, the signal processing unit 104 controls the piezoelectric element driver 105 so that the piezoelectric element 106 vibrates at the same frequency as the fixed periodic frequency of the laser light. In the present embodiment, the piezoelectric element 106 is provided in the discharge tube 108, and the vibration thereof can adjust the flow rate of the gas in the discharge tube 108.
[0046]
FIG. 1B is a cross-sectional view of the inside of the discharge tube 108. The discharge tube 108 is filled with a gas used as a laser medium. The gas is circulated in the discharge tube 108 by the blower 110. The gas sent from the blower 110 passes between the anode 112 and the cathode 113 of the main discharge tube 111 and then circulates through the heat exchanger 114 to return to the blower 110 again. The heat exchanger 114 has a function of radiating heat generated in the main discharge tube 111 and keeping the temperature of the gas in the discharge tube 108 constant.
[0047]
In the present embodiment, the pre-ionization electrode 115 is provided on the upstream side and the downstream side of the main discharge tube 111 to perform pre-ionization with ultraviolet rays (ultraviolet pre-ionization method). The preionization method is not limited to the preionization method. For example, other preionization methods such as a corona preionization method and an X-ray preionization method may be used.
[0048]
The piezoelectric element 106 is desirably provided on the downstream side of the blower 110 and on the upstream side of the main discharge tube 111. The piezoelectric element 106 vibrates according to the voltage applied from the piezoelectric element driver 105. When the piezoelectric element 106 vibrates, the gas flow generated by the vibration of the piezoelectric element 106 is added to the gas flow generated by the blower 110, and as a result, the flow rate of the gas flowing through the main discharge tube 111 is adjusted.
[0049]
In the present embodiment, the gas flow is caused by the piezoelectric element 106 itself, but the gas flow may be caused indirectly by transmitting the vibration of the piezoelectric element 106 to something other than the piezoelectric element. good. In this case, the piezoelectric element does not necessarily need to be provided inside the discharge tube 108.
[0050]
The flow rate of the gas caused only by the vibration of the piezoelectric element 106 is adjusted so as to fluctuate at the same frequency as the periodic vibration and at the opposite phase.
[0051]
In the present embodiment, an electric signal including the state of the fluctuation of the gas pressure in the vicinity of the main discharge tube 111 as data is generated using the gas sensor 107 and input to the signal processing unit 104. Then, the signal processing unit 104 performs signal processing such as FFT on the electric signal, thereby grasping the state of the fluctuation of the gas pressure in the vicinity of the main discharge tube 111, and reducing the height difference of the fluctuation by using the piezoelectric element. The amplitude and phase of the vibration of the piezoelectric element 106 are adjusted using the driver 105. The gas sensor 107 is desirably upstream of the main discharge tube 111 and downstream of the piezoelectric element 106.
[0052]
FIG. 4A shows a waveform of the periodic fluctuation of the energy of the laser light calculated from the fast Fourier transform. Assuming that the fixed period frequency is 1 / T, the period of the fixed period fluctuation is represented by T. A represents the amplitude of the periodic fluctuation of the laser light. FIG. 4B shows a waveform of a change in the gas flow rate caused by only the vibration of the piezoelectric element 106, which is generated from the waveform of the periodic change shown in FIG. The waveform of the change in the gas flow rate caused only by the vibration of the piezoelectric element 106 has the same cycle T as the waveform of the periodic change, and the phase is shifted by T / 2. B indicates the amplitude of the flow rate.
[0053]
The amplitude B of the flow rate of the gas caused only by the vibration of the piezoelectric element 106 is the energy of the laser beam obtained when the flow rate has the maximum value, and the energy of the laser beam obtained when the flow rate has the minimum value. Is set to be closer.
[0054]
The laser light whose energy has been adjusted by the vibration of the piezoelectric element 106 is emitted from the oscillator 100. With the above-described correction means, in the laser device of the present invention, it is possible to suppress fluctuations in the energy of the laser light output from the oscillator 100. More specifically, the periodic fluctuation of the energy of the laser beam can be suppressed.
[0055]
Next, the phase control will be described in detail.
[0056]
In FIG. 5A, the waveform of the laser light before correction is shown by a broken line, and the waveform of the laser light after correction is shown by a solid line. FIG. 5A shows a case where the phase of the periodic fluctuation of the energy and the phase of the fluctuation of the flow rate of the gas caused only by the vibration of the piezoelectric element 106 are shifted by exactly a half cycle. However, in FIG. 5A, only the waveform of the periodic fluctuation confirmed by the signal processing is shown for easy understanding of the waveform of the periodic fluctuation. In FIG. 5A, the waveform of the laser light before the correction and the waveform of the laser light after the correction have the same phase. Therefore, it is considered that the phase of the change in the gas flow rate caused only by the vibration of the piezoelectric element 106 is set to be exactly T / 2 different from the phase of the periodic change of the laser beam. Then, by adjusting the amplitude of the flow rate so that the amplitude A ′ of the laser light becomes smaller, the stability of the energy of the laser light can be further improved.
[0057]
Next, in FIG. 5B, when the phase shift is not T / 2, the waveform of the laser light before correction is shown by a broken line, and the waveform of the laser light after correction is shown by a solid line. However, like FIG. 5 (A), FIG. 5 (B) shows only the waveform of the periodic fluctuation confirmed by the signal processing in order to make the waveform of the periodic fluctuation easy to understand. In FIG. 5B, the waveform of the laser light before correction and the waveform of the laser light after correction do not have the same phase. Therefore, it is predicted that the difference between the phase of the fluctuation of the gas flow rate caused only by the vibration of the piezoelectric element 106 and the phase of the periodic fluctuation of the laser beam is not T / 2. In this case, the signal processing unit separately adjusts the phase to suppress the periodic fluctuation of the laser light.
[0058]
Note that the adjustment of the amplitude and the phase is not limited to the method described in this embodiment. The amplitude and the phase may be adjusted while monitoring the laser light so that the maximum value and the minimum value of the periodic fluctuation of the energy of the laser light output from the oscillator become closer. In this case, it is not always necessary to use the gas sensor 107 to monitor the fluctuation of the gas pressure near the main discharge tube 111. Since the energy may fluctuate due to factors other than the gas pressure, the phase difference is not always T / 2. Therefore, adjustment while monitoring the laser light makes it easier to find an appropriate phase difference, and can more reliably suppress fluctuations in the laser light than monitoring gas pressure.
[0059]
The phase can be adjusted by monitoring the corrected laser beam energy or the gas pressure near the main discharge tube 111, but the phase adjustment is not limited to this configuration. For example, the phase of the oscillation of the piezoelectric element 106 and the phase of the energy of the laser light may be matched with reference to a signal synchronized with the oscillation of the laser light in the oscillator. Specifically, the phase can be matched by calculating the phase difference from a signal (reference signal) in which the phase difference between the frequency and the fluctuation of the laser light is known in advance and the constant periodic frequency of the laser light. it can.
[0060]
Further, the correction means stores information on the frequency and amplitude of the vibration of the piezoelectric element determined by the signal processing unit in a memory or the like, so as to eliminate the need to adjust the frequency and amplitude of the vibration of the piezoelectric element again next time. You may do it.
[0061]
In the present embodiment, a piezoelectric element is used as the flow rate adjusting means, but the present invention is not limited to this. Any means capable of adjusting the flow rate of gas in the discharge tube can be used as the flow rate adjusting means in the present invention. For example, an electromagnetic valve for supplying gas into the discharge tube and an electromagnetic valve for exhausting gas from the discharge tube may be provided, and the flow rate of the gas may be adjusted by opening these two electromagnetic valves.
[0062]
In addition, even in the case of non-periodic energy fluctuations, non-periodic fluctuations can be suppressed as long as the gas flow rate can be adjusted at such a speed that the monitored result can be immediately fed back to the laser beam.
[0063]
【Example】
Hereinafter, examples of the present invention will be described.
[0064]
(Example 1)
The periodic fluctuation of the energy of the laser beam differs depending on the oscillation frequency of the oscillator. In this embodiment, the relationship between the oscillation frequency of the laser light emitted from the oscillator of the excimer laser and the frequency of the periodic fluctuation will be described.
[0065]
FIG. 6 shows the relationship between the oscillation frequency (Hz) of the laser beam and the highest peak frequency (Hz) obtained by Fourier transform. The horizontal axis indicates the oscillation frequency (Hz), and the vertical axis indicates the peak position (Hz) after Fourier transform. Note that the measurement dates are different for each measurement, but the measurement conditions other than the oscillation frequency are the same.
[0066]
The highest peak frequency obtained by Fourier transform means the frequency of the periodic fluctuation of the energy of the laser light. The frequency of the periodic fluctuation repeatedly increases and decreases in steps. Specifically, the frequency of the periodic fluctuation has a minimum value when the oscillation frequency is about 3 Hz, 12 Hz, and 25 Hz, and has a maximum value when the oscillation frequency is about 3 Hz, 10 Hz, and 22 Hz. After the oscillation frequency exceeds about 25 Hz, it continues to increase.
[0067]
As shown in FIG. 6, by examining in advance the relationship between the oscillation frequency of the laser light to be used and the frequency of the periodic fluctuation, the optimum conditions for actually irradiating the laser light to the workpiece are searched for. Can help. For example, by selecting a condition under which the frequency of the periodic fluctuation becomes high, the interval between the horizontal stripes of the semiconductor film caused by the periodic fluctuation can be shortened to the extent that it cannot be visually recognized. Conversely, by selecting a condition that lowers the frequency of the periodic fluctuation, the interval between the horizontal stripes of the semiconductor film generated by the periodic fluctuation can be increased so that the horizontal stripe does not appear in the irradiation region. .
[0068]
Based on the data in FIG. 6, the same number of shots (about 13 shots) as under the standard laser beam irradiation conditions (oscillation frequency of 30 Hz, scan speed of 1.0 mm / sec) used for crystallization of the semiconductor film was obtained. The laser beam irradiation is performed so as to calculate the interval between the horizontal stripes expected to occur at each oscillation frequency. Specifically, it is calculated from Equation 2 below.
[0069]
[Equation 2]

d (ω): interval of horizontal stripes
ω: oscillation frequency
ω ₀ : Oscillation frequency under standard irradiation conditions (= 30 Hz)
ν ₀ : Substrate scan speed under standard irradiation conditions (= 1.0 mm / sec)
T (ω): Frequency of periodic fluctuation
[0070]
FIG. 7 shows the relationship between the oscillation frequency and the period of the horizontal stripe calculated from Equation 2. A characteristic peak appeared at the oscillation frequency ω = 25 Hz, and the horizontal stripes at 25 Hz were predicted to be about 3.9 mm apart. At other oscillation frequencies, the interval was about 60 to about 500 μm. The assumed value of the substrate scanning speed at 25 Hz is 0.833 mm / sec when the number of shots is adjusted to the standard condition (30 Hz, 1.0 mm / sec).
[0071]
(Example 2)
Example 1 In this example, an example of the laser device of the present invention described in the embodiment mode will be described.
[0072]
FIG. 8 shows the configuration of the laser device of this embodiment. A part of the laser light emitted from the oscillator 1500 is sampled in the optical system 1501. The sampled laser light enters the laser light sensor 1502.
[0073]
On the other hand, the remaining laser light other than the sampled laser light enters the beam expander 1503. In this embodiment, a shutter 1504 for blocking laser light is provided in the optical path between the oscillator 1500 and the beam expander 1503, but is not necessarily provided.
[0074]
The spread of the incident laser light can be suppressed by the beam expander 1503, and the size of the beam spot can be adjusted.
[0075]
The laser beam emitted from the beam expander 1503 is condensed by the beam homogenizer 1505 so that the beam spot has a rectangular, elliptical, or linear shape. Then, the collected laser light is reflected by the mirror 1506 and enters the lens 1507. The incident laser light is condensed again by the lens 1507 and is irradiated on the substrate 1508 on which the semiconductor film is formed. In this embodiment, a cylindrical lens is used as the lens 1507.
[0076]
The substrate 1508 is mounted on a stage 1509, and the position of the stage 1509 is controlled by three position control means (drivers) 1510 to 1512. Specifically, the stage 1509 can be rotated in a horizontal plane by the φ-direction position control means 1510. Further, the stage 1509 can be moved in the X direction within the horizontal plane by the X direction position control means 1511. Further, the stage 1509 can be moved in the Y direction within the horizontal plane by the Y direction position control means 1512. The operation of each position control means is controlled by the central processing unit 1519.
[0077]
By controlling the operations of the three position control means described above, the position of the substrate 1508 at which the laser light is irradiated can be controlled.
[0078]
On the other hand, the laser light sensor 1502 converts the sampled laser light into an electric signal and inputs the electric signal to the signal processing unit 1513. The electric signal has a state of fluctuation of the energy of the laser light as data. Then, the data is analyzed by the signal processing in the signal processing unit 1513, and the state of the fluctuation of the energy of the laser light is grasped.
[0079]
Further, a reference signal synchronized with the emission of the laser light is input from the oscillator 1500 to the signal processing unit 1513. The signal processing unit 1513 adjusts the flow rate of gas in the discharge tube provided in the oscillator 1500 using the grasped fluctuation state, the reference signal, and the like.
[0080]
Note that the correction means of the present invention includes an optical system 1501, a sensor 1502, a signal processing unit 1513, and a means for adjusting the flow rate of a gas provided in the discharge tube.
[0081]
Further, as in this embodiment, a monitor 1514 using a light receiving element such as a CCD may be provided so that the position of the substrate can be accurately grasped.
[0082]
The laser beam scanning method includes an irradiation system moving type in which the object to be processed is fixed and the laser light irradiation position is moved, and an object moving type in which the laser light irradiation position is fixed and the object is moved. And a method combining the above two methods.
[0083]
Although the laser device shown in FIG. 8 is of a moving type of an object to be processed, the present invention is not limited thereto. The present invention can also be applied to an irradiation system movable laser device or a laser device combining an object moving type and an irradiation system movable type. Irradiation with laser light is performed so that beam spots of the laser light on the semiconductor film overlap in the scanning direction.
[0084]
This embodiment can be implemented in combination with the first embodiment.
[0085]
【The invention's effect】
According to the present invention, by monitoring the fluctuation of the energy of the laser beam, the energy of the laser beam can be precisely controlled, so that the fluctuation of the laser beam can be canceled more reliably than the conventional method of monitoring the gas pressure. And a laser beam having more stable energy can be obtained. More specifically, it is possible to suppress the fluctuation of the energy of the laser light that occurs periodically.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a correction unit.
FIG. 2 is a graph showing measured values of energy for each oscillation frequency.
FIG. 3 is a graph showing measured data of energy for each oscillation frequency after FFT.
FIG. 4 is a diagram showing a periodic change in energy and a change in flow rate.
FIG. 5 is a diagram showing a change in energy of laser light.
FIG. 6 is a graph showing a relationship between an oscillation frequency and a peak position of a frequency after Fourier transform.
FIG. 7 is a diagram showing the relationship between the oscillation frequency and the interval between horizontal stripes when the number of shots is adjusted to the standard.
FIG. 8 is a diagram showing a configuration of a laser device of the present invention.
FIG. 9 is a graph showing energy values of laser light with respect to time and data after FFT.
FIG. 10 is a photograph of a semiconductor film which is irradiated with laser light from an excimer laser and crystallized, as viewed from above.
11A and 11B are a photograph of a semiconductor film after crystallization as viewed from above, and a diagram showing the energy values of laser light in different shades.
12A and 12B are a photograph of a semiconductor film after crystallization viewed from above and a photograph of a pixel portion of a light-emitting device formed using the semiconductor film.

Claims (8)

An optical system for sampling a part of the laser light emitted from the oscillator,
Means for generating an electric signal including data of a change in energy of the laser light using the part of the laser light,
A flow rate adjusting means for adjusting a gas flow rate in a discharge tube of the oscillator, and a signal processing on the electric signal to grasp a state of a change in the energy of the laser beam, and the state of the grasped energy. And a signal processing unit that controls the flow rate adjusting unit to adjust the flow rate of the gas so as to suppress the fluctuation of the energy of the laser light.
A laser device comprising: An optical system for sampling a part of the laser light emitted from the oscillator,
Means for generating a first electric signal including a change in energy of the laser light as data using the part of the laser light,
A flow rate adjusting means for adjusting a gas flow rate in the discharge tube of the oscillator, and measuring a pressure of the gas at a specific position in the discharge tube to generate a second electric signal including the pressure value as data; Means,
By performing signal processing on the first electric signal, the state of fluctuation of the energy of the laser beam is grasped, and by performing signal processing on the second electric signal, the pressure of the gas at the specific position is grasped. And, based on the state of the grasped energy and the pressure of the gas, a signal processing unit that controls the flow rate adjusting means to adjust the flow rate of the gas so as to suppress the fluctuation of the energy of the laser light. ,
A laser device comprising: Sampling a part of the laser light oscillated from the oscillator, to generate an electrical signal including a change in energy of the laser light as data,
By performing signal processing on the electric signal, grasping the state of fluctuation of the energy of the laser light,
A laser irradiation method, comprising: controlling a flow rate adjusting means to adjust a flow rate of the gas based on the grasped energy state so as to suppress a change in energy of the laser light. Sampling a part of the laser light oscillated from the oscillator to generate a first electric signal including a change in energy of the laser light as data;
Measuring a pressure of the gas at a specific position in the discharge tube, generating a second electric signal including the value of the pressure as data,
By performing signal processing on the first electric signal, the state of energy fluctuation of the laser light is grasped,
By performing signal processing on the second electric signal, grasp the pressure of the gas at the specific position,
A step of controlling a flow rate adjusting means to adjust a flow rate of the gas based on the grasped state of energy and a pressure of the gas so as to suppress a change in energy of the laser beam. Method. Sampling a part of the laser light oscillated from the oscillator, to generate an electrical signal including a change in energy of the laser light as data,
By performing signal processing on the electric signal, grasping the state of fluctuation of the energy of the laser light,
Based on the state of the grasped energy, the flow rate of the gas is adjusted by controlling the flow rate adjusting means so as to suppress the fluctuation of the energy of the laser beam,
By irradiating the semiconductor film with laser light obtained by adjusting the flow rate of the gas so that beam spots on the semiconductor film overlap in the scanning direction, the crystallinity of the semiconductor film is increased. Of manufacturing a semiconductor device. Sampling a part of the laser light oscillated from the oscillator to generate a first electric signal including a change in energy of the laser light as data;
Measuring a pressure of the gas at a specific position in the discharge tube, generating a second electric signal including the value of the pressure as data,
By performing signal processing on the first electric signal, the state of energy fluctuation of the laser light is grasped,
By performing signal processing on the second electric signal, grasp the pressure of the gas at the specific position,
Based on the grasped energy state and the gas pressure, the flow rate of the gas is adjusted by controlling the flow rate adjusting means so as to suppress the fluctuation of the energy of the laser beam,
By irradiating the semiconductor film with laser light obtained by adjusting the flow rate of the gas so that beam spots on the semiconductor film overlap in the scanning direction, the crystallinity of the semiconductor film is increased. Of manufacturing a semiconductor device. Sampling a part of the laser light oscillated from the oscillator, to generate an electrical signal including a change in energy of the laser light as data,
By performing signal processing on the electric signal, grasping the state of fluctuation of the energy of the laser light,
Based on the state of the grasped energy, the flow rate of the gas is adjusted by controlling the flow rate adjusting means so as to suppress the fluctuation of the energy of the laser beam,
By irradiating the semiconductor film with laser light obtained by adjusting the flow rate of the gas so that beam spots on the semiconductor film overlap in the scanning direction, the crystallinity of the semiconductor film is increased. Semiconductor device. Sampling a part of the laser light oscillated from the oscillator to generate a first electric signal including a change in energy of the laser light as data;
Measuring a pressure of the gas at a specific position in the discharge tube, generating a second electric signal including the value of the pressure as data,
By performing signal processing on the first electric signal, the state of energy fluctuation of the laser light is grasped,
By performing signal processing on the second electric signal, grasp the pressure of the gas at the specific position,
Based on the grasped energy state and the gas pressure, the flow rate of the gas is adjusted by controlling the flow rate adjusting means so as to suppress the fluctuation of the energy of the laser beam,
By irradiating the semiconductor film with laser light obtained by adjusting the flow rate of the gas so that beam spots on the semiconductor film overlap in the scanning direction, the crystallinity of the semiconductor film is increased. Semiconductor device.

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