JP2004029234A

JP2004029234A - Optical system and apparatus for projection exposure

Info

Publication number: JP2004029234A
Application number: JP2002183258A
Authority: JP
Inventors: Shuichi Takeuchi; 竹内　修一; Yutaka Takakubo; 高窪　豊
Original assignee: Pentax Corp
Current assignee: Pentax Corp
Priority date: 2002-06-24
Filing date: 2002-06-24
Publication date: 2004-01-29
Anticipated expiration: 2022-06-24
Also published as: JP4224805B2

Abstract

<P>PROBLEM TO BE SOLVED: To adjust projection magnification while employing a constitution such that the optical axis of an imaging lens is set parallel to a mask surface and a projected surface and luminous flux which travels forward and backward in the imaging lens is guided to the projected surface by using a mirror. <P>SOLUTION: A projection exposure optical system 10 projects light emitted by an illumination optical system 1 to expose a plate 3 to a pattern of the mask 2 almost with nonmagnification and has 1st and 2nd condenser lenses 11 and 15 having a common optical axis nearly perpendicular to the mask 2 and plate 3 and an imaging lens 13 having an optical axis perpendicular thereto; and the luminous flux from the mask 2 is made incident on the imaging lens 13 by a 1st mirror 12a, reflected by a 2nd mirror 14, passed through the imaging lens 13, and then reflected by the 3rd mirror 12b to be made incident on the 2nd condenser lens 15. The 2nd condenser lens 15 is movable along the optical axis A×1 for magnification adjustment. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、プリント基板や液晶ディスプレイパネルの製造工程においてフォトリソグラフィの手法でパターンを露光、描画する際に利用される投影露光装置、および、これに含まれる投影露光光学系に関する。
【０００２】
【従来の技術】
従来から、この種の用途には、物体側のマスクに形成されたパターンを複数の投影露光光学系を用いてほぼ等倍でマスクとほぼ平行な被投影面上に投影し、マスクと被投影面とを投影露光光学系に対して移動させることによりパターンの像を被投影面上に形成する走査型の投影露光装置が用いられている。それぞれの投影露光光学系が走査により帯状の領域を露光することができ、複数の投影露光光学系により形成される複数の帯状の領域を切れ目なく繋ぐことにより、広い領域にパターンを形成することができる。
【０００３】
パターンを等倍で投影するためには、一定の物像間距離が必要であるが、単一の直線状の光軸に沿って光学系の各レンズを配置すると、マスク面、被投影面に対して垂直な方向における光学系のサイズが大きく、この光学系を用いる装置のサイズも大きくなる。そこで、例えば特開平７−３２６５５７号公報には、結像レンズの光軸をマスク面、被投影面に対して平行になるように設定し、結像レンズの光軸上で一方側に直角プリズム、他方側に平面ミラーを配置し、マスクからの光束を直角プリズムの一面で反射させて結像レンズに入射させ、結像レンズを透過した光束を平面ミラーにより反射させて再び結像レンズに入射させ、結像レンズを往復した光束を直角プリズムの他方の面で反射させて被投影面に導く投影露光光学系が開示されている。このような構成によれば、上記の物像間距離を保ちつつ、マスク面、被投影面に対して垂直な方向における光学系のサイズを小さくすることができる。
【０００４】
なお、投影露光装置では、被投影面に配置される基板の温度変化による伸縮や、他工程における倍率誤差を補正するため、投影倍率を変更しなければならない場合がある。
【０００５】
【発明が解決しようとする課題】
しかしながら、上述した公報に記載された投影露光光学系は、投影光束が全てのレンズ要素を往復する構成であるため、一部のレンズを光軸方向に移動させたとしても、移動による光学特性の変化が結像レンズの物体側、像側の双方に対して等しく現れるため、投影倍率を調整するのが難しいという問題がある。
【０００６】
この発明は、上述した従来技術の問題点に鑑みてなされたものであり、結像レンズの光軸をマスク面、被投影面に対して平行になるように設定し、ミラーを用いて結像レンズ内を往復した光束を被投影面に導く構成を採用しつつ、投影倍率を容易に調整することができる投影露光光学系を提供することを目的とする。
【０００７】
【課題を解決するための手段】
この発明にかかる投影露光光学系は、上記の目的を達成させるため、物体側のパターンをこのパターンとほぼ平行な被投影面上に投影露光する構成において、パターンおよび被投影面に対してほぼ垂直な共通の第１の光軸を持ち、光学的なパワーを持つ第１，第２の光学素子と、第１，第２の光学素子の中間位置で第１の光軸に対して垂直に交差する第２の光軸を持つ結像光学系と、パターンから発して第１の光学素子を透過した光束を反射させて結像光学系に入射させる第１のミラーと、結像光学系の瞳位置の近傍に配置されて結像光学系を透過した光束を反射させて再び結像光学系に入射させる第２のミラーと、結像レンズを往復した光束を反射させて第２の光学素子に入射させる第３のミラーとを備え、第１、第２の光学素子の少なくとも一方が第１の光軸方向に移動可能であり、この光学素子の移動により被投影面上に形成された像の倍率を調整可能としたことを特徴とする。
【０００８】
上記の構成によれば、結像光学系とは別個に配置され、投影光束が一回しか透過しない第１，第２の光学素子の少なくとも一方を第１の光軸方向に移動させることにより、投影倍率を容易に調整することができる。
【０００９】
また、第１、第２の光学素子の少なくとも一方の第１の光軸方向への移動に伴って被投影面、あるいは物体側のパターンを第１の光軸方向へ移動させれば、倍率の調整によってずれた像のピントを合わせることができる。さらに、第１、第２の光学素子の少なくとも一方を第１の光軸に直交し、第２の光軸と平行な方向に移動可能とすれば、第１、第２の光学素子の少なくとも一方の第１の光軸方向への移動に伴う像の歪みを補正することができる。第１、第２の光学素子の少なくとも一方を第１、第２の光軸の双方に対して直交する方向に移動させれば、第１、第２の光軸の双方に対して直交する方向の像の位置が調整できる。あるいは、第２のミラーが１つの反射面を持つ平面ミラーである場合には、これを第１の光軸と平行な軸回りに回動させても、第１、第２の光軸の双方に対して直交する方向の像の位置が調整できる。
【００１０】
一方、第２のミラーは、ダハミラー、あるいはダハプリズムのような互いに直交する２つの反射面をもつミラーとすると、レンズ系の一回の結像により形成される倒立像を正立させることができる。このとき、第２のミラーを第２の光軸回りに回動可能とすれば、像の傾きを調整することができ、さらに、第２のミラーを第１、第２の光軸の双方に対して垂直な軸回りに回動可能とすれば、像の位置ズレを補正することができる。
【００１１】
第１，第２の光学素子は、正のパワーを持つことが望ましく、特に、光学系を物体側、像側の双方に対してテレセントリックにするためのコンデンサレンズとしての機能を持つことが望ましい。
【００１２】
【発明の実施の形態】
以下、この発明にかかる投影露光光学系の実施形態を図１〜図９に基づいて説明する。
図１は実施形態の投影露光光学系の具体的な構成を示すレンズ図、図２は投影露光光学系の概略を示す斜視図、図３は投影露光光学系の光路を展開して示すレンズ図である。
【００１３】
実施形態の投影露光光学系１０は、照明光学系１から発してマスク２を透過した光をマスク２とほぼ平行な被投影面であるプレート３に投影し、マスク２に形成されたパターンをほぼ等倍でプレート３に投影露光する。マスク２は、所定の回路パターンが形成された透過型の基板であり、プレート３は、フォトレジスト等の感光材料が塗布された基板である。投影露光光学系１０を介してマスク２に形成されたパターンをプレート３に投影露光することにより、プレート３上の感光材料を感光させてパターンを転写することができる。
【００１４】
投影露光光学系１０は、図１に示すように、マスク２およびプレート３に対してほぼ垂直な共通の第１の光軸Ａｘ１を持ち、光学的なパワーを持つ第１，第２の光学素子として、それぞれ正のパワーを持つ第１，第２のコンデンサレンズ１１、１５を備えている。第１，第２のコンデンサレンズ１１、１５は、投影露光光学系１０を物体（マスク）側、像（プレート）側の双方に対してテレセントリックにするためのパワーを有する。また、投影露光光学系１０は、第１，第２のコンデンサレンズの中間位置で第１の光軸Ａｘ１に対して垂直に交差する第２の光軸Ａｘ２を持つ結像レンズ１３と、マスク２から発して第１のコンデンサレンズ１１を透過した光束を反射させて結像レンズ１３に入射させる第１のミラー１２ａと、結像レンズ１３の瞳位置の近傍に配置されて結像レンズ１３を透過した光束を反射させて再び結像レンズ１３に入射させる第２のミラー１４と、結像レンズ１３を往復した光束を反射させて第２のコンデンサレンズ１５に入射させる第３のミラー１２ｂとを備える。
【００１５】
ここで、図中にＸ−Ｙ−Ｚの三次元座標を定義する。Ｘ軸は、第１の光軸Ａｘ１に対して平行、Ｚ軸は、第２の光軸Ａｘ２に対して平行、Ｙ軸は、２つの光軸の双方に対して垂直である。
【００１６】
マスク２側に配置された第１のコンデンサレンズ１１は、マスク２に平面を向けて配置された平凸レンズであり、投影されるパターンＰ（図２参照）より大きな直径を有する。プレート３側に配置された第２のコンデンサレンズ１５は、第１のコンデンサレンズ１１と同一設計の平凸レンズであり、プレート３に平面を向けて配置されている。この例では、図中矢印で示したように、第２のコンデンサレンズ１５が第１の光軸Ａｘ１に沿って移動可能であり、かつ、プレート３が同様に光軸Ａｘ１に沿って移動可能である。なお、第２のコンデンサレンズ１５とプレート３との間には、投影露光される領域を限定する視野絞りＳが配置されている。
【００１７】
第１，第３のミラー１２ａ，１２ｂは、両コンデンサレンズの間に配置された直角プリズム１２の互いに直交する２つの面にアルミ等の反射コーティングを施すことにより、単一の部品として構成されている。直角プリズム１２は、第１，第３ミラー１２ａ，１２ｂの境界となる直角プリズム１２の稜線が、Ｙ軸に対して平行となり、かつ、第１の光軸Ａｘ１と第２の光軸Ａｘ２との交点を通るように配置されている。
【００１８】
結像レンズ１３は、直角プリズム１２側から順に、両凹の第１レンズ１３ａ、正メニスカスの第２レンズ１３ｂ、両凸の第３レンズ１３ｃ、正メニスカスの第４レンズ１３ｄ、正負貼り合わせの第５レンズ１３ｅとが配列して構成されている。
【００１９】
第２のミラー１４は、図２に示したように、互いに直交して向かい合う２つの反射面を有する、いわゆるダハミラーであり、２つの反射面の境界線となる稜線が基準状態で第１の光軸Ａｘ１と平行になるように配置されている。
【００２０】
露光時には、照明光学系１を点灯させることにより、マスク２上の所定の領域Ｐ内のパターンが、投影露光光学系１０を介して等倍でプレート３上の領域Ｐ’内に形成される。複数の投影露光光学系を並べてマスク２上の連続した領域のパターンを分割して同時に投影するためには、各投影露光光学系が正立像を形成する必要がある。但し、コンデンサレンズと結像レンズとによる結像では倒立像が形成されるため、第２のミラー１４としてダハミラーを用いている。これにより、マスク２上のパターンを正立像としてプレート３上に形成することができる。照明光学系１を点灯させた状態で、マスク２とプレート３とを同時に等速度でＺ軸方向に走査させることにより、領域Ｐ’の幅で帯状の領域にマスクのパターンを投影露光することができる。
【００２１】
プレート３の温度変化による伸縮や、他工程における倍率誤差を補正するには、第２のコンデンサレンズ１５を第１の光軸Ａｘ１方向に移動させることにより、投影倍率を変化させ、像のサイズを調整する。また、このとき、プレート３を第１の光軸Ａｘ１方向に移動させることにより、倍率調整によってずれた像のピントを合わせることができる。倍率調整の具体例を図３〜図６にしたがって説明する。
【００２２】
図３は、投影露光光学系１０の倍率調整前後の配置を光路を展開して示したレンズ図、図４はその拡大図である。第２の投影レンズ１５、プレート３は、等倍での投影時には図中に破線で示した位置に配置されている。第２のコンデンサレンズ１５よりプレート３側の光路は、倍率調整の前後で変化する。等倍時の光線は破線で示されている。投影倍率を調整して像のサイズを小さくするには、第２のコンデンサレンズ１５を第１の光軸Ａｘ１に沿って実線の位置まで移動させる。第２のコンデンサレンズ１５を移動させると、光線は実線で示すように進む。これにより、像の形成される範囲は狭くなる。ただし、単に第２のコンデンサレンズ１５を移動させるのみでは、像の形成位置が第１の光軸Ａｘ１の方向にずれるため、プレート３に形成される像のピントがずれることになる。そこで、プレート３を破線に示す等倍時の位置から実線で示す位置まで移動させる。これにより、像のピントを合わせることができる。
【００２３】
なお、第２のコンデンサレンズ１５のパワーが大きい場合、あるいは、倍率調整のための移動量が大きい場合、像が湾曲する可能性がある。この湾曲と、その補正方法について、図５、図６を参照して説明する。図５及び図６は、図２と同様に投影露光光学系１０の全体構成を示す斜視図である。ただし、ここでは説明を簡単にするため、マスク２上の直線パターンＬがプレート３上に投影される場合について説明する。
【００２４】
図５に示すように、等倍時には破線の位置に配置されていた第２のコンデンサレンズ１５を、倍率調整、この例では像のサイズを拡大するため、第１の光軸Ａｘ１に沿ってプレート３側に移動させる。等倍時には、マスク２上の直線パターンＬは、プレート３上では破線で示す直線状の像Ｌ’として形成される。ここで、第２のコンデンサレンズ１５を図中の矢印で示すように移動させると、像Ｌ１’は実線で示すように湾曲する場合がある。このように像が湾曲すると、マスク２上のパターンをプレート３上に正確に投影することができず、投影性能を劣化させる。
【００２５】
そこで、倍率調整により像が湾曲する場合には、図６に示すように、第２のコンデンサレンズ１５を第１の光軸Ａｘ１に直交し、第２の光軸Ａｘ２と平行な方向、すなわちＺ方向に移動させる。図６では、倍率調整後、湾曲補正前のレンズ位置、光線、像を破線で示し、湾曲補正のためにＺ方向に移動された第２のコンデンサレンズ１５の位置を実線で示すと共に、補正後の像Ｌ２’を実線で示している。第２のコンデンサレンズ１５をＺ方向に移動させると、大きく湾曲していた像Ｌ１’の湾曲が低減され、より直線に近い像Ｌ２’を形成することができる。
【００２６】
次に、上記の倍率調整と同時に、あるいは、倍率調整とは独立して、像のＹ方向の位置、Ｙ−Ｚ面内での傾き、Ｚ方向の位置を調整するための方法を図７〜図９に基づいて説明する。
像のＹ方向の位置は、図７に拡大して示すように、第２のコンデンサレンズ１５をＹ方向に平行移動させることにより、調整することができる。調整前、第２のコンデンサレンズ１５が破線で示した位置に配置されている場合、光線は破線で示すように進み、プレート３上で範囲Ｒ１内に像が形成される。位置調整のために第２のコンデンサレンズ１５を実線で示した位置に移動させると、光路は実線で示すように変化し、プレート３上では範囲Ｒ２内に像が形成される。すなわち、第２のコンデンサレンズ１５をＹ方向に平行移動させることにより、像の形成範囲もＹ方向に沿ってＲ１からＲ２へと変化する。
【００２７】
像のＹ−Ｚ面内での傾きは、図８に示すように、第２のミラー１４を第２の光軸Ａｘ２回りに回動させることにより調整することができる。調整前、第２のミラー１４が破線で示した位置に配置されている場合、光線は破線で示すように進み、マスク２上の直線パターンＬは、プレート３上では破線で示す直線状の像Ｌ’として形成される。傾き調整のために第２のミラー１４を第２の光軸Ａｘ２回りに回動させて実線で示した位置に変位させると、光路は実線で示すように変化し、プレート３上では像Ｌ３’は実線で示すように調整前の像Ｌ’に対して傾斜する。
【００２８】
像のＺ方向の位置は、図９に示すように、第２のミラー１４を第１、第２の光軸Ａｘ１、Ａｘ２の双方に対して垂直な軸、すなわち、Ｙ方向の軸回りに回動させることにより、調整することができる。調整前、第２のミラー１４が破線で示した位置に配置されている場合、光線は破線で示すように進み、マスク２上の直線パターンＬは、プレート３上では破線で示す直線状の像Ｌ’として形成される。位置調整のために第２のミラー１４をＹ方向の軸Ｙ１回りに回動させて実線で示した位置に変位させると、光路は実線で示すように変化し、プレート３上では像Ｌ４’は実線で示すように調整前の像Ｌ’に対してＺ方向に移動する。
【００２９】
図１０は、上記の投影露光光学系１０を２系統組み合わせて構成される走査型の投影露光装置の概略を示す斜視図である。結像レンズ１３は、その光軸が互いに平行になるように隣接してＹ方向に一列に配列しており、一方の投影露光光学系に含まれるコンデンサレンズ１１，１５、直角プリズム１２、第２ミラー１４は、他方の投影露光光学系に含まれる該当部材に対して結像レンズ１３を挟んで反対側に配置されている。
【００３０】
図１１は、第２のミラーとして、上述のダハミラー１４に代えて、１つの反射面を持つ平面ミラーを用いた投影露光光学系の実施形態を示す斜視図である。ダハミラー１４を用いる場合には、第１のコンデンサレンズ１１から結像レンズ１３を介して第２のコンデンサレンズ１５に至るレンズ系と組み合わせて一回の結像で正立像を形成することができる。
【００３１】
これに対して第２のミラーとして平面ミラー１６を用いる場合には、一回の結像では倒立像が形成される。そこで、ここでは第１のコンデンサレンズ１１から結像レンズ１３を介して第２のコンデンサレンズ１５に至るレンズ系を備える第１の光学系１０と、同様に第１のコンデンサレンズ１１’から結像レンズ１３’を介して第２のコンデンサレンズ１５’に至る第２の光学系１０’とを直列に配置することにより、２回の結像で正立像を形成する。それぞれの光学系に第２のミラーとして平面ミラー１６、１６’が設けられており、第２の光学系１０’に含まれる第２のミラー１６’が、第１の光軸Ａｘ１と平行な軸回りに回動可能とされている。平面ミラー１６’を回転調整することにより、第１、第２の光軸の双方に対して直交する方向、すなわちＹ方向の像の位置を調整することできる。
【００３２】
なお、図１１の構成においても、図１の実施形態と同様に、いずれかの光学系のコンデンサレンズを第１の光軸Ａｘ１方向に移動させることにより倍率の調整が可能であり、このとき、マスク２、あるいはプレート３を第１の光軸Ａｘ１方向に移動させることにより、ピントを合わせることが可能である。
【００３３】
【発明の効果】
以上説明したように、この発明の投影露光光学系によれば、ミラーを用いて結像レンズ内を往復した光束を被投影面に導く構成を採用しつつ、投影倍率を容易に調整することができ、被投影面に配置される基板の温度変化による伸縮や、他工程における倍率誤差を補正することができる。
【図面の簡単な説明】
【図１】実施形態の投影露光光学系の具体的な構成を示すレンズ図である。
【図２】図１に示す投影露光光学系の概略を示す斜視図である。
【図３】図１に示す投影露光光学系の光路を展開して示すレンズ図である。
【図４】図３に示す投影露光光学系の一部拡大図である。
【図５】図１に示す投影露光光学系で像の倍率を調整する方法を示す斜視図である。
【図６】図１に示す投影露光光学系で倍率調整による像の湾曲を補正する方法を示す斜視図である。
【図７】図１に示す投影露光光学系で像のＹ方向の位置を調整する方法を示す斜視図である。
【図８】図１に示す投影露光光学系で像の傾きを調整する方法を示す斜視図である。
【図９】図１に示す投影露光光学系で像のＺ方向の位置を調整する方法を示す斜視図である。
【図１０】図１の投影露光光学系を２系統組み合わせて構成される走査型の投影露光装置の概略を示す斜視図である。
【図１１】他の実施形態の投影露光光学系の概略を示す斜視図である。
【符号の説明】
１０　投影露光光学系
１１　第１のコンデンサレンズ
１２　直角プリズム
１２ａ　第１のミラー
１２ｂ　第３のミラー
１３　結像レンズ
１４　第２のミラー
１５　第２のコンデンサレンズ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projection exposure apparatus used when a pattern is exposed and drawn by a photolithographic technique in a manufacturing process of a printed circuit board or a liquid crystal display panel, and a projection exposure optical system included therein.
[0002]
[Prior art]
Conventionally, for this type of application, the pattern formed on the object-side mask is projected onto the projection surface at approximately the same magnification and parallel to the mask using a plurality of projection exposure optical systems. 2. Description of the Related Art A scanning type projection exposure apparatus that forms an image of a pattern on a projection surface by moving a surface with respect to a projection exposure optical system is used. Each projection exposure optical system can expose a band-shaped area by scanning, and a pattern can be formed in a wide area by continuously connecting a plurality of band-shaped areas formed by a plurality of projection exposure optical systems. it can.
[0003]
In order to project the pattern at the same magnification, a certain distance between the object images is necessary. However, if each lens of the optical system is arranged along a single linear optical axis, the mask surface and the projection surface are projected. On the other hand, the size of the optical system in the direction perpendicular thereto is large, and the size of the apparatus using this optical system is also large. Therefore, for example, in Japanese Patent Laid-Open No. 7-326557, the optical axis of the imaging lens is set to be parallel to the mask surface and the projection surface, and a right-angle prism on one side on the optical axis of the imaging lens. A flat mirror is placed on the other side, the light beam from the mask is reflected by one surface of the right-angle prism and incident on the imaging lens, and the light beam transmitted through the imaging lens is reflected by the flat mirror and incident on the imaging lens again. A projection exposure optical system is disclosed in which a light beam reciprocating through an imaging lens is reflected by the other surface of a right-angle prism and guided to a projection surface. According to such a configuration, the size of the optical system in the direction perpendicular to the mask surface and the projection surface can be reduced while maintaining the distance between the object images.
[0004]
In the projection exposure apparatus, the projection magnification may need to be changed in order to correct expansion / contraction due to a temperature change of the substrate arranged on the projection surface and a magnification error in another process.
[0005]
[Problems to be solved by the invention]
However, since the projection exposure optical system described in the above-mentioned publication has a configuration in which the projected light beam reciprocates all the lens elements, even if some lenses are moved in the optical axis direction, the optical characteristics due to the movement are reduced. Since the change appears equally on both the object side and the image side of the imaging lens, there is a problem that it is difficult to adjust the projection magnification.
[0006]
The present invention has been made in view of the above-described problems of the prior art. The optical axis of the imaging lens is set to be parallel to the mask surface and the projection surface, and an image is formed using a mirror. An object of the present invention is to provide a projection exposure optical system capable of easily adjusting the projection magnification while adopting a configuration in which a light beam reciprocating in a lens is guided to a projection surface.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the projection exposure optical system according to the present invention is configured so that an object side pattern is projected and exposed on a projection surface substantially parallel to the pattern, and is substantially perpendicular to the pattern and the projection surface. First and second optical elements having a common first optical axis and having optical power, and perpendicularly intersecting the first optical axis at an intermediate position between the first and second optical elements. An imaging optical system having a second optical axis, a first mirror that reflects a light beam emitted from the pattern and transmitted through the first optical element, and enters the imaging optical system, and a pupil of the imaging optical system A second mirror disposed near the position for reflecting the light beam transmitted through the imaging optical system and re-entering the imaging optical system; and a light beam reciprocating through the imaging lens is reflected to the second optical element. A third mirror to be incident, and less of the first and second optical elements Even one being movable in a first optical axis direction, characterized in that the adjustable magnification of the image formed on the projection surface by the movement of the optical element.
[0008]
According to the above configuration, by moving at least one of the first and second optical elements, which are arranged separately from the imaging optical system and through which the projection light beam is transmitted only once, in the first optical axis direction, The projection magnification can be easily adjusted.
[0009]
Further, if the projection surface or the object-side pattern is moved in the first optical axis direction along with the movement of at least one of the first and second optical elements in the first optical axis direction, the magnification can be increased. The image shifted by adjustment can be focused. Further, if at least one of the first and second optical elements is movable in a direction perpendicular to the first optical axis and parallel to the second optical axis, at least one of the first and second optical elements is used. The distortion of the image accompanying the movement in the first optical axis direction can be corrected. If at least one of the first and second optical elements is moved in a direction orthogonal to both the first and second optical axes, the direction orthogonal to both the first and second optical axes The position of the image can be adjusted. Alternatively, when the second mirror is a plane mirror having one reflecting surface, both the first and second optical axes can be obtained even if the second mirror is rotated around an axis parallel to the first optical axis. The position of the image in the direction orthogonal to the direction can be adjusted.
[0010]
On the other hand, if the second mirror is a mirror having two reflecting surfaces orthogonal to each other such as a roof mirror or roof prism, an inverted image formed by a single image formation of the lens system can be erected. At this time, if the second mirror can be rotated about the second optical axis, the inclination of the image can be adjusted, and further, the second mirror can be adjusted to both the first and second optical axes. On the other hand, if it is possible to rotate about a vertical axis, the positional deviation of the image can be corrected.
[0011]
The first and second optical elements desirably have positive power, and particularly desirably function as a condenser lens for making the optical system telecentric on both the object side and the image side.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a projection exposure optical system according to the present invention will be described below with reference to FIGS.
FIG. 1 is a lens diagram showing a specific configuration of the projection exposure optical system of the embodiment, FIG. 2 is a perspective view schematically showing the projection exposure optical system, and FIG. 3 is a lens diagram showing the optical path of the projection exposure optical system in an expanded manner. It is.
[0013]
The projection exposure optical system 10 of the embodiment projects the light emitted from the illumination optical system 1 and transmitted through the mask 2 onto the plate 3 that is a projection surface substantially parallel to the mask 2, and the pattern formed on the mask 2 is substantially Projection exposure is performed on the plate 3 at the same magnification. The mask 2 is a transmissive substrate on which a predetermined circuit pattern is formed, and the plate 3 is a substrate coated with a photosensitive material such as a photoresist. By projecting and exposing the pattern formed on the mask 2 onto the plate 3 via the projection exposure optical system 10, the photosensitive material on the plate 3 can be exposed to transfer the pattern.
[0014]
As shown in FIG. 1, the projection exposure optical system 10 has a common first optical axis Ax1 substantially perpendicular to the mask 2 and the plate 3, and first and second optical elements having optical power. Are provided with first and second condenser lenses 11 and 15 each having a positive power. The first and second condenser lenses 11 and 15 have power to make the projection exposure optical system 10 telecentric with respect to both the object (mask) side and the image (plate) side. The projection exposure optical system 10 includes an imaging lens 13 having a second optical axis Ax2 perpendicularly intersecting the first optical axis Ax1 at an intermediate position between the first and second condenser lenses, and the mask 2. The first mirror 12 a that reflects the light beam emitted from the first condenser lens 11 and reflects it to enter the imaging lens 13, and is disposed in the vicinity of the pupil position of the imaging lens 13 and transmits through the imaging lens 13. The second mirror 14 that reflects the reflected light beam and enters the imaging lens 13 again, and the third mirror 12b that reflects the light beam that reciprocates through the imaging lens 13 and enters the second condenser lens 15 are provided. .
[0015]
Here, XYZ three-dimensional coordinates are defined in the figure. The X axis is parallel to the first optical axis Ax1, the Z axis is parallel to the second optical axis Ax2, and the Y axis is perpendicular to both of the two optical axes.
[0016]
The first condenser lens 11 disposed on the mask 2 side is a plano-convex lens disposed with its plane facing the mask 2, and has a larger diameter than the projected pattern P (see FIG. 2). The second condenser lens 15 disposed on the plate 3 side is a plano-convex lens having the same design as the first condenser lens 11 and is disposed with the plane facing the plate 3. In this example, as indicated by an arrow in the figure, the second condenser lens 15 is movable along the first optical axis Ax1, and the plate 3 is also movable along the optical axis Ax1. is there. A field stop S that restricts the area to be projected and exposed is disposed between the second condenser lens 15 and the plate 3.
[0017]
The first and third mirrors 12a and 12b are configured as a single component by applying a reflective coating such as aluminum on two mutually orthogonal surfaces of the right-angle prism 12 disposed between the condenser lenses. Yes. In the right-angle prism 12, the ridge line of the right-angle prism 12 serving as the boundary between the first and third mirrors 12a and 12b is parallel to the Y axis, and the first optical axis Ax1 and the second optical axis Ax2 It is arranged to pass through the intersection.
[0018]
The imaging lens 13 includes, in order from the right-angle prism 12 side, a biconcave first lens 13a, a positive meniscus second lens 13b, a biconvex third lens 13c, a positive meniscus fourth lens 13d, and positive and negative bonded first lenses. 5 lenses 13e are arranged.
[0019]
As shown in FIG. 2, the second mirror 14 is a so-called roof mirror having two reflecting surfaces that are orthogonal to each other, and the ridgeline that is a boundary line between the two reflecting surfaces is the first light in the reference state. It arrange | positions so that it may become parallel with axis | shaft Ax1.
[0020]
At the time of exposure, the illumination optical system 1 is turned on to form a pattern in a predetermined region P on the mask 2 in the region P ′ on the plate 3 at the same magnification via the projection exposure optical system 10. In order to arrange a plurality of projection exposure optical systems and divide a pattern of a continuous area on the mask 2 and project simultaneously, it is necessary for each projection exposure optical system to form an erect image. However, since an inverted image is formed in the imaging with the condenser lens and the imaging lens, a roof mirror is used as the second mirror 14. Thereby, the pattern on the mask 2 can be formed on the plate 3 as an erect image. When the illumination optical system 1 is turned on, the mask 2 and the plate 3 are simultaneously scanned at the same speed in the Z-axis direction, thereby projecting and exposing the mask pattern onto the band-like region with the width of the region P ′. it can.
[0021]
In order to correct expansion / contraction due to temperature change of the plate 3 and magnification error in other processes, the projection magnification is changed by moving the second condenser lens 15 in the direction of the first optical axis Ax1, and the image size is changed. adjust. At this time, by moving the plate 3 in the direction of the first optical axis Ax1, it is possible to focus the image shifted by the magnification adjustment. A specific example of the magnification adjustment will be described with reference to FIGS.
[0022]
FIG. 3 is a lens diagram showing the arrangement of the projection exposure optical system 10 before and after the magnification adjustment in an expanded optical path, and FIG. 4 is an enlarged view thereof. The second projection lens 15 and the plate 3 are arranged at the positions indicated by the broken lines in the drawing at the same magnification. The optical path on the plate 3 side from the second condenser lens 15 changes before and after the magnification adjustment. The rays at the same magnification are indicated by broken lines. In order to reduce the image size by adjusting the projection magnification, the second condenser lens 15 is moved along the first optical axis Ax1 to the position of the solid line. When the second condenser lens 15 is moved, the light beam travels as shown by the solid line. Thereby, the range in which an image is formed becomes narrow. However, if the second condenser lens 15 is simply moved, the image forming position is shifted in the direction of the first optical axis Ax1, so that the image formed on the plate 3 is out of focus. Therefore, the plate 3 is moved from the position at the same magnification indicated by the broken line to the position indicated by the solid line. As a result, the image can be focused.
[0023]
Note that when the power of the second condenser lens 15 is large, or when the amount of movement for adjusting the magnification is large, the image may be curved. This curvature and its correction method will be described with reference to FIGS. 5 and 6 are perspective views showing the overall configuration of the projection exposure optical system 10 as in FIG. However, here, in order to simplify the description, a case where the linear pattern L on the mask 2 is projected onto the plate 3 will be described.
[0024]
As shown in FIG. 5, the second condenser lens 15 arranged at the position of the broken line at the same magnification is subjected to a plate adjustment along the first optical axis Ax1 in order to adjust the magnification, in this example, to enlarge the size of the image. Move to side 3. At the same magnification, the linear pattern L on the mask 2 is formed as a linear image L ′ indicated by a broken line on the plate 3. Here, when the second condenser lens 15 is moved as indicated by an arrow in the drawing, the image L1 ′ may be curved as indicated by a solid line. When the image is curved in this manner, the pattern on the mask 2 cannot be accurately projected onto the plate 3 and the projection performance is deteriorated.
[0025]
Therefore, when the image is curved by adjusting the magnification, as shown in FIG. 6, the second condenser lens 15 is orthogonal to the first optical axis Ax1 and parallel to the second optical axis Ax2, that is, Z Move in the direction. In FIG. 6, the lens position, the light beam, and the image before the curvature correction after the magnification adjustment are indicated by a broken line, the position of the second condenser lens 15 moved in the Z direction for the curvature correction is indicated by a solid line, and after the correction. The image L2 ′ is indicated by a solid line. When the second condenser lens 15 is moved in the Z direction, the curvature of the greatly curved image L1 ′ is reduced, and an image L2 ′ that is closer to a straight line can be formed.
[0026]
Next, a method for adjusting the position of the image in the Y direction, the tilt in the YZ plane, and the position in the Z direction simultaneously with the above magnification adjustment or independently of the magnification adjustment is shown in FIGS. This will be described with reference to FIG.
The position of the image in the Y direction can be adjusted by translating the second condenser lens 15 in the Y direction as shown in an enlarged view in FIG. Before the adjustment, when the second condenser lens 15 is disposed at the position indicated by the broken line, the light beam proceeds as indicated by the broken line, and an image is formed on the plate 3 within the range R1. When the second condenser lens 15 is moved to the position indicated by the solid line for position adjustment, the optical path changes as indicated by the solid line, and an image is formed on the plate 3 within the range R2. In other words, when the second condenser lens 15 is translated in the Y direction, the image formation range also changes from R1 to R2 along the Y direction.
[0027]
The tilt of the image in the YZ plane can be adjusted by rotating the second mirror 14 about the second optical axis Ax2, as shown in FIG. Before the adjustment, when the second mirror 14 is arranged at the position indicated by the broken line, the light beam proceeds as indicated by the broken line, and the linear pattern L on the mask 2 is a linear image indicated by the broken line on the plate 3. Formed as L ′. When the second mirror 14 is rotated about the second optical axis Ax2 and displaced to the position indicated by the solid line for tilt adjustment, the optical path changes as indicated by the solid line, and the image L3 ′ on the plate 3 changes. Is inclined with respect to the image L ′ before adjustment as indicated by a solid line.
[0028]
As shown in FIG. 9, the position of the image in the Z direction rotates the second mirror 14 around an axis perpendicular to both the first and second optical axes Ax1 and Ax2, that is, an axis in the Y direction. It can be adjusted by moving it. Before the adjustment, when the second mirror 14 is arranged at the position indicated by the broken line, the light beam proceeds as indicated by the broken line, and the linear pattern L on the mask 2 is a linear image indicated by the broken line on the plate 3. Formed as L ′. When the second mirror 14 is rotated about the Y-axis Y1 to adjust the position and displaced to the position indicated by the solid line, the optical path changes as indicated by the solid line, and the image L4 ′ is displayed on the plate 3 as shown in FIG. As indicated by the solid line, the image moves in the Z direction with respect to the image L ′ before adjustment.
[0029]
FIG. 10 is a perspective view showing an outline of a scanning projection exposure apparatus configured by combining two systems of the projection exposure optical system 10 described above. The imaging lenses 13 are arranged adjacent to each other in the Y direction so that their optical axes are parallel to each other. The condenser lenses 11 and 15, the right-angle prism 12 and the second prism included in one projection exposure optical system. The mirror 14 is arranged on the opposite side of the corresponding member included in the other projection exposure optical system with the imaging lens 13 interposed therebetween.
[0030]
FIG. 11 is a perspective view showing an embodiment of a projection exposure optical system using a plane mirror having one reflecting surface in place of the roof mirror 14 as the second mirror. When the roof mirror 14 is used, an erect image can be formed by one image formation in combination with a lens system that extends from the first condenser lens 11 to the second condenser lens 15 via the imaging lens 13.
[0031]
On the other hand, when the plane mirror 16 is used as the second mirror, an inverted image is formed by one image formation. Therefore, here, the first optical system 10 having a lens system extending from the first condenser lens 11 through the imaging lens 13 to the second condenser lens 15 is similarly imaged from the first condenser lens 11 ′. An erect image is formed by two imaging operations by arranging in series with the second optical system 10 ′ that reaches the second condenser lens 15 ′ via the lens 13 ′. Planar mirrors 16 and 16 ′ are provided as second mirrors in the respective optical systems, and the second mirror 16 ′ included in the second optical system 10 ′ is an axis parallel to the first optical axis Ax1. It can be turned around. By rotating and adjusting the plane mirror 16 ', the position of the image in the direction orthogonal to both the first and second optical axes, that is, the Y direction can be adjusted.
[0032]
11, the magnification can be adjusted by moving the condenser lens of any one of the optical systems in the direction of the first optical axis Ax1, as in the embodiment of FIG. The focus can be adjusted by moving the mask 2 or the plate 3 in the direction of the first optical axis Ax1.
[0033]
【The invention's effect】
As described above, according to the projection exposure optical system of the present invention, it is possible to easily adjust the projection magnification while adopting the configuration in which the light beam reciprocating in the imaging lens is guided to the projection surface using the mirror. It is possible to correct expansion / contraction due to temperature change of the substrate arranged on the projection surface and magnification error in other processes.
[Brief description of the drawings]
FIG. 1 is a lens diagram showing a specific configuration of a projection exposure optical system according to an embodiment.
FIG. 2 is a perspective view schematically showing the projection exposure optical system shown in FIG.
3 is a lens diagram in which an optical path of the projection exposure optical system shown in FIG. 1 is developed. FIG.
4 is a partially enlarged view of the projection exposure optical system shown in FIG.
5 is a perspective view showing a method for adjusting the magnification of an image with the projection exposure optical system shown in FIG. 1; FIG.
6 is a perspective view showing a method for correcting the curvature of an image by adjusting the magnification in the projection exposure optical system shown in FIG. 1. FIG.
7 is a perspective view showing a method of adjusting the position of the image in the Y direction with the projection exposure optical system shown in FIG. 1. FIG.
8 is a perspective view showing a method for adjusting the tilt of an image with the projection exposure optical system shown in FIG. 1. FIG.
9 is a perspective view showing a method for adjusting the position of an image in the Z direction with the projection exposure optical system shown in FIG. 1. FIG.
10 is a perspective view schematically showing a scanning projection exposure apparatus configured by combining two systems of the projection exposure optical system of FIG.
FIG. 11 is a perspective view schematically showing a projection exposure optical system according to another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Projection exposure optical system 11 1st condenser lens 12 Right angle prism 12a 1st mirror 12b 3rd mirror 13 Imaging lens 14 2nd mirror 15 2nd condenser lens

Claims

In a projection exposure optical system for projecting and exposing a pattern on the object side onto a projection surface substantially parallel to the pattern,
First and second optical elements having a common first optical axis substantially perpendicular to the pattern and the projection surface and having optical power;
An imaging optical system having a second optical axis perpendicularly intersecting the first optical axis at an intermediate position between the first and second optical elements;
A first mirror that reflects a light beam emitted from the pattern and transmitted through the first optical element to enter the imaging optical system;
A second mirror that is disposed in the vicinity of the pupil position of the imaging optical system and reflects the light beam that has passed through the imaging optical system to enter the imaging optical system again;
A third mirror that reflects the light beam reciprocating through the imaging lens and makes it incident on the second optical element;
At least one of the first and second optical elements is movable in the first optical axis direction, and the magnification of an image formed on the projection surface can be adjusted by the movement of the optical element. A projection exposure optical system characterized by the above.

The projection surface is movable in the first optical axis direction, and the projection surface is moved along the movement of at least one of the first and second optical elements in the first optical axis direction. The projection exposure optical system according to claim 1, wherein the image can be focused by moving in the first optical axis direction.

The object-side pattern is movable in the first optical axis direction, and the object-side pattern is accompanied by movement of at least one of the first and second optical elements in the first optical axis direction. The projection exposure optical system according to claim 1, wherein the image can be focused by moving the lens in the first optical axis direction.

At least one of the first and second optical elements is movable in a direction perpendicular to the first optical axis and parallel to the second optical axis, and at least one of the first and second optical elements. The projection exposure optical system according to claim 1, wherein distortion of an image accompanying movement in one of the first optical axis directions can be corrected.

At least one of the first and second optical elements is movable in a direction perpendicular to both the first and second optical axes, and with respect to both the first and second optical axes. 4. The projection exposure optical system according to claim 1, wherein the position of the image in the orthogonal direction can be adjusted.

The second mirror is a plane mirror having a single reflecting surface, and is rotatable about an axis parallel to the first optical axis. Both the first and second optical axes are 5. The projection exposure optical system according to claim 1, wherein the position of an image in a direction orthogonal to the adjustment is adjustable.

The second mirror can be rotated around an axis orthogonal to both the first and second optical axes, and the position of the image in a direction parallel to the second optical axis can be adjusted. The projection exposure optical system according to claim 1, wherein the projection exposure optical system is a projection exposure optical system.

The projection exposure optical system according to claim 1, wherein the second mirror has two reflecting surfaces orthogonal to each other.

9. The projection exposure optical system according to claim 8, wherein the second mirror is rotatable about the second optical axis, and the inclination of the image can be adjusted.

The projection exposure optical system according to claim 1, wherein the first and second optical elements have positive power.

11. The projection exposure optics according to claim 10, wherein the first and second optical elements have a function as a condenser lens for making the optical system telecentric with respect to both the object side and the image side. system.

A projection exposure apparatus comprising: a plurality of projection exposure optical systems according to claim 1 arranged in a direction orthogonal to both the first and second optical axes.