JP2004126100A - Projection optical system, aligner and exposure method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection optical system having high numerical aperture and capable of making the minimum line width of an exposure pattern small. <P>SOLUTION: The projection optical system forming the image of a reticle R on a wafer W is equipped with a first lens group G1 arranged nearest to the reticle side out of lens groups in the projection optical system, including at least two negative lenses and having negative refractive power, a second lens group G2 arranged in an optical path between the first lens group and the wafer, including at least three positive lenses and having positive refractive power, a third lens group G3 arranged in an optical path between the second lens group and the wafer, including at least two biconcave lenses and having negative refractive power, and a fourth lens group G4 arranged in an optical path between the third lens group and the wafer, including an aperture diaphragm AS and having positive refractive power. The fourth lens group is equipped with a first positive lens group, a first negative lens group and a second positive lens group on the reticle side of the aperture diaphragm, and equipped with a third positive lens group, a second negative lens group and a fourth positive lens group on the wafer side of the aperture diaphragm. <P>COPYRIGHT: (C)2004,JPO

Description

【００４４】
また、表２において、非球面形状を表す係数を示す。ここで非球面形状を以下に示す数式１にて定義する。
【００４５】
【数１】

【００４６】
ただし、Ｚはｓａｇ量、ｈは光軸からの距離、ｒは面頂点の曲率半径、ｋは円錐係数（ｋ＝０の時は球面）である。
【００４７】
【表２】

【００４８】
次に、第１の実施例にかかる条件式に対応する値（条件対応値）を示す。
Ｄ１＝１２２．２７１
Ｌ＝１２５０
Ｄ１／Ｌ＝０．０９８
図３は、第１の実施例にかかる投影光学系の縦収差を示し、図４は、その子午方向（タンジェンシャル方向）及び球欠方向（サジタル方向）における横収差（コマ収差）を示している。各収差図において、Ｎ．Ａ．は投影光学系ＰＬのウエハＷ側の開口数、ｆｉｅｌｄ　ｈｅｉｇｈｔはウエハＷ側の像高を示しており、非点収差図中において、点線は子午像面（タンジェンシャル像面）、実線は球欠像面（サジタル像面）を示している。
【００４９】
この第１の実施例にかかる投影光学系、即ち、この高開口数を有する投影光学系においては、球面収差、歪曲収差（ディストーション）、コマ収差等がバランス良く補正されていることが理解できる。
【００５０】
次に、第２の実施例にかかる投影光学系の構成を説明する。図５は、第２の実施例にかかる投影光学系のレンズ断面図である。この投影光学系ＰＬは、第１物体としてのレチクルＲ側から、両凹レンズＬ２１０１，Ｌ２１０２により構成される負の屈折力を有する第１レンズ群Ｇ１、両凸レンズＬ２２０１，Ｌ２２０２，Ｌ２２０３、レチクル側に凸面を向けた正メニスカスレンズＬ２２０４、両凸レンズＬ２２０５により構成される正の屈折力を有する第２レンズ群Ｇ２、両凹レンズＬ２３０１，Ｌ２３０２，Ｌ２３０３，両凹レンズ（第３負レンズ群）Ｌ２３０４により構成される負の屈折力を有する第３レンズ群Ｇ３、レチクル側に凹面を向けた正メニスカスレンズ（第２正レンズ群）Ｌ２４０１，レチクル側に凹面を向けた正メニスカスレンズ（第２正レンズ群）Ｌ２４０２、レチクル側に凹面を向けた負メニスカスレンズ（第１負レンズ群）Ｌ２４０３、レチクル側に凹面を向けた正メニスカスレンズ（第１正レンズ群）Ｌ２４０４、レチクル側に凹面を向けた正メニスカスレンズ（第３正レンズ群）Ｌ２４０５、レチクル側に凹面を向けた平凹レンズ（第２負レンズ群）Ｌ２４０６、レチクル側に凹面を向けた正メニスカスレンズ（第４正レンズ群）Ｌ２４０７、レチクル側に凸面を向けた正メニスカスレンズ（第４正レンズ群）Ｌ２４０８，レチクル側に凸面を向けた正メニスカスレンズ（第４正レンズ群）Ｌ２４０９、両凹レンズ（第４負レンズ群）Ｌ２４１０、レチクル側に凸面を向けた正メニスカスレンズＬ２４１１、レクチル側に凸面を向けた平凸レンズＬ２４１２により構成される正の屈折力を有する第４レンズ群Ｇ４の４群（Ｇ１〜Ｇ４）によって構成されている。
【００５１】
なお、正メニスカスレンズＬ２４０４と正メニスカスレンズＬ２４０５の間に、開口絞りＡＳが配置されている。また、第１正レンズ群、第２正レンズ群、第３正レンズ群、第４正レンズ群は、１以上の正レンズを有し且つ負レンズを含まないレンズ群であり、第１負レンズ群、第２負レンズ群、第３負レンズ群、第４負レンズ群は、１以上の負レンズを有し且つ正レンズを含まないレンズ群である。
【００５２】
この投影光学系によれば、第４レンズ群Ｇ４において、開口絞りＡＳに対して、屈折力が対称系となるようにレンズ群が配置されている。即ち、開口絞りＡＳのレチクルＲ側に隣接して第１正レンズ群Ｌ２４０４、第１正レンズ群Ｌ２４０４のレチクルＲ側に隣接して第１負レンズ群Ｌ２４０３、第１負レンズ群Ｌ２４０３のレチクルＲ側に隣接して第２正レンズ群Ｌ２４０１，Ｌ２４０２が配置されると共に、開口絞りＡＳのウエハＷ側に隣接して第３正レンズ群Ｌ２４０５、第３正レンズ群Ｌ２４０５のウエハＷ側に隣接して第２負レンズ群２４０６、第２負レンズ群２４０６のウエハＷ側に隣接して第４正レンズ群２４０７，Ｌ２４０８，Ｌ２４０９が配置されている。従って、横収差であるコマ収差、歪曲収差、更には倍率色収差の補正を有利に行うことができる。また、開口絞りＡＳよりもウエハＷ側に負レンズ群が配置されていることから、開口絞りからウエハＷまでの間のペッツバル和の補正を容易に行うことができ、瞳収差の補正を有利に行うことができる。
【００５３】
この投影光学系は、第４レンズ群Ｇ４が第１正レンズ群Ｌ２４０４と第３正レンズ群Ｌ２４０５との間に配置された気体レンズを備えている。この気体レンズの軸上厚さをＤ１とし、投影光学系の全長をＬとするとき、
０．０２＜（Ｄ１／Ｌ）＜０．２
の条件を満足する。
【００５４】
この投影光学系によれば、第１正レンズ群Ｌ２４０４と第３正レンズ群Ｌ２４０５との間の光路中に厚さの厚い気体レンズを備えることにより、即ち０．０２＜（Ｄ１／Ｌ）の条件を満足することにより、可変絞り等により構成される開口絞りの配置位置の幅を大きくすることができ、可変絞り機構等を配置する際の設計自由度を大きくすることができる。一方、（Ｄ１／Ｌ）＜０．２の条件を満足することにより投影光学系が巨大化するのを防止することができる。
【００５５】
更に、第４レンズ群Ｇ４の第１正レンズ群Ｌ２４０４、気体レンズ及び第３正レンズ群Ｌ２４０５が全体として正の屈折力を有する群を構成することから、厚さの厚い気体レンズにより第１正レンズ群、気体レンズ及び第３正レンズ群の凸レンズ作用を軽減することができ、球面収差の発生を低減させることができる。従って、正の屈折力を有する第４レンズ群においては球面収差の発生が抑制されていることから、第２レンズ群の正の屈折力を低減させることができ、第２レンズ群において一枚毎のレンズの屈折力の低減が可能になる。
【００５６】
また、この投影光学系は、第４レンズ群Ｇ４が第１正レンズ群Ｌ２４０４と第１負レンズ群Ｌ２４０３との間の光路中に配置されて正の屈折力を有する気体レンズ（第１気体レンズ）と、第３正レンズ群Ｌ２４０５と第２負レンズ群Ｌ２４０６との間の光路中に配置されて正の屈折力を有する気体レンズ（第２気体レンズ）とを備える。即ち、開口絞りに対して対称に正の屈折力を有する気体レンズが配置されるため、横収差の補正状態を保ちながら縦収差である球面収差の補正を有利に行うことができ、大開口数の投影光学系を実現することができる。
【００５７】
また、この投影光学系においては、投影光学系を構成するレンズがＡｒＦエキシマレーザの波長（波長λ＝１９３ｎｍ）における硝材屈折率ｎ＝１．５６０３２６の合成石英（ＳｉＯ_２）又は、ＡｒＦエキシマレーザの波長（波長λ＝１９３ｎｍ）における硝材屈折率ｎ＝１．５０１４５５の蛍石（ＣａＦ_２）により形成されている。第４レンズ群Ｇ４においては、正メニスカスレンズＬ２４１１、レクチル側に凸面を向けた平凸レンズＬ２４１２が蛍石により形成されている。第４レンズ群Ｇ４において蛍石により構成された正レンズを有することから、軸上色収差の補正を有利に行うことができる。
【００５８】
また、この投影光学系は、第２正レンズ群Ｌ２４０１，Ｌ２４０２と第３レンズ群Ｇ３との間の光路中に第３負レンズ群Ｌ２３０４が配置され、第４正レンズ群Ｌ２４０７，Ｌ２４０８，Ｌ２４０９とウエハＷとの間の光路中に第４負レンズ群Ｌ２４１０が配置されているため、高次球面収差の補正を有利に行うことができる。
【００５９】
また、投影光学系ＰＬ内に非球面ＡＳＰ１〜ＡＳＰ８を有するように構成されている。即ち第１レンズ群Ｇ１において両凹レンズＬ２１０１のウエハＷ側のレンズ面が非球面ＡＳＰ１として構成されており、両凹レンズＬ２１０２のレチクルＲ側のレンズ面が非球面ＡＳＰ２として構成されている。また、第３レンズ群Ｇ３において両凹レンズＬ２３０１のウエハＷ側のレンズ面が非球面ＡＳＰ３として構成されており、両凹レンズＬ２３０２のレチクルＲ側のレンズ面が非球面ＡＳＰ４として構成されており、両凹レンズＬ２３０３のウエハＷ側のレンズ面が非球面ＡＳＰ５として構成されており、両凹レンズＬ２３０４のウエハＷ側のレンズ面が非球面ＡＳＰ６として構成されている。また、第４レンズ群Ｇ４において正メニスカスレンズＬ２４０９のウエハＷ側のレンズ面が非球面ＡＳＰ７として構成されており、両凹レンズＬ１４１０のウエハＷ側のレンズ面が非球面ＡＳＰ８として構成されている。この投影光学系によれば、第１レンズ群Ｇ１及び第３レンズ群Ｇ３の少なくとも一方のレンズ群が非球面形状のレンズ面を備えるため、コマ収差、歪曲収差等、画角によって異なる高次収差の補正を有利に行うことができる。
【００６０】
次に、第２の実施例にかかる投影光学系の諸元値を表３に示す。ここで、投影光学系の設計諸元を以下に示す。
開口数（Ｎ．Ａ．）＝０．８５
露光フィールド＝２６×８（ｍｍ）
結像倍率＝１／４倍
物体−光学系距離：５８．９０５５８（ｍｍ）
像−光学系距離：１１．５９５５１（ｍｍ）
投影光学系全長（Ｌ）：１２５０（ｍｍ）
表３において、面番号はレチクルＲ側からのレンズ面の順序、ｒは該当レンズ面の曲率半径、ｄは該当レンズ面から次のレンズ面までの光軸上の間隔、有効径は各レンズ面における有効径、ｎはＡｒＦエキシマレーザの波長（波長λ＝１９３ｎｍ）における硝材屈折率をそれぞれ示している。
【００６１】
【表３】

【００６２】
また、表４において、非球面形状を表す係数を示す。ここで非球面形状は、上述の数式１にて定義する。
【００６３】
【表４】

【００６４】
次に、第２の実施例にかかる条件式に対応する値（条件対応値）を示す。
Ｄ１＝８８．４７５４７
Ｌ＝１２５０
Ｄ１／Ｌ＝０．０７１
図６は、第２の実施例にかかる投影光学系の縦収差を示し、図７は、その子午方向（タンジェンシャル方向）及び球欠方向（サジタル方向）における横収差（コマ収差）を示している。各収差図において、Ｎ．Ａ．は投影光学系ＰＬのウエハＷ側の開口数、ｆｉｅｌｄ　ｈｅｉｇｈｔはウエハＷ側の像高を示しており、非点収差図中において、点線は子午像面（タンジェンシャル像面）、実線は球欠像面（サジタル像面）を示している。
【００６５】
この第２の実施例にかかる投影光学系、即ち、この高開口数を有する投影光学系においては、球面収差、歪曲収差（ディストーション）、コマ収差等がバランス良く補正されていることが理解できる。
【００６６】
なお、上記の実施の形態では、露光光としてＡｒＦエキシマレーザ光を用いた例を示したが、本発明はこれに限定されることなく、ＫｒＦエキシマレーザ光や、水銀ランプのｇ線、ｉ線等、更にはそれ以外の波長の光を使用する場合にも適用できることは言うまでもない。
【００６７】
上述の実施の形態にかかる露光装置では、照明光学装置によってレチクル（マスク）を照明し（照明工程）、投影光学系を用いてマスクに形成された転写用のパターンを感光性基板に露光する（露光工程）ことにより、マイクロデバイス（半導体素子、撮像素子、液晶表示素子、薄膜磁気ヘッド等）を製造することができる。以下、図１に示す実施の形態の露光装置を用いて感光基板としてのウエハ等に所定の回路パターンを形成することによって、マイクロデバイスとしての半導体デバイスを得る半導体デバイスの製造方法を、図８のフローチャートを参照して説明する。
【００６８】
先ず、図８のステップ３０１において、１ロットのウエハ上に金属膜が蒸着される。次のステップ３０２において、その１ロットのウエハ上の金属膜上にフォトレジストが塗布される。その後、ステップ３０３において、図１に示す露光装置を用いて、マスク上のパターンの像がその投影光学系を介して、その１ロットのウエハ上の各ショット領域に順次露光転写される。即ち、照明光学装置によりマスクを照明し（照明工程）、マスクのパターンをウエハ上に転写する（露光工程）。
【００６９】
その後、ステップ３０４において、その１ロットのウエハ上のフォトレジストの現像が行われた後、ステップ３０５において、その１ロットのウエハ上でレジストパターンをマスクとしてエッチングを行うことによって、マスク上のパターンに対応する回路パターンが、各ウエハ上の各ショット領域に形成される。その後、更に上のレイヤの回路パターンの形成等を行うことによって、半導体素子等のデバイスが製造される。上述の半導体デバイス製造方法によれば、極めて微細な回路パターンを有する半導体デバイスをスループット良く得ることができる。
【００７０】
また、図１に示す本実施の形態の露光装置では、プレート（ガラス基板）上に所定のパターン（回路パターン、電極パターン等）を形成することによって、マイクロデバイスとしての液晶表示素子を得ることもできる。以下、図９のフローチャートを参照して、マイクロデバイスとしての液晶表示素子を製造する方法を説明する。図９において、パターン形成工程４０１では、図１に示す露光装置を用いてマスクのパターンを感光性基板（レジストが塗布されたガラス基板等）に転写露光する、所謂光リソグラフィ工程が実行される。この光リソグラフィ工程によって、感光性基板上には多数の電極等を含む所定パターンが形成される。その後、露光された基板は、現像工程、エッチング工程、レチクル剥離工程等の各工程を経ることによって、基板上に所定のパターンが形成され、次のカラーフィルター形成工程４０２へ移行する。
【００７１】
次に、カラーフィルター形成工程４０２では、Ｒ（Ｒｅｄ）、Ｇ（Ｇｒｅｅｎ）、Ｂ（Ｂｌｕｅ）に対応した３つのドットの組がマトリックス状に多数配列され、またはＲ、Ｇ、Ｂの３本のストライプのフィルターの組を複数水平走査線方向に配列したカラーフィルターを形成する。そして、カラーフィルター形成工程４０２の後に、セル組み立て工程４０３が実行される。セル組み立て工程４０３では、パターン形成工程４０１にて得られた所定パターンを有する基板、およびカラーフィルター形成工程４０２にて得られたカラーフィルター等を用いて液晶パネル（液晶セル）を組み立てる。セル組み立て工程４０３では、例えば、パターン形成工程４０１にて得られた所定パターンを有する基板とカラーフィルター形成工程４０２にて得られたカラーフィルターとの間に液晶を注入して、液晶パネル（液晶セル）を製造する。
【００７２】
その後、モジュール組み立て工程４０４にて、組み立てられた液晶パネル（液晶セル）の表示動作を行わせる電気回路、バックライト等の各部品を取り付けて液晶表示素子として完成させる。上述の液晶表示素子の製造方法によれば、極めて微細な回路パターンを有する液晶表示素子をスループット良く得ることができる。
【００７３】
【発明の効果】
この発明の投影光学系によれば、第４正レンズ群において、開口絞りに対して、屈折力が対称系となるようにレンズ群が配置されているため、横収差であるコマ収差、ディストーション、更には倍率色収差の補正を有利に行うことができる。また、開口絞りよりも第２面側に負レンズ群が配置されていることから、開口絞りから第２面までの間のペッツバル和の補正を容易に行うことができ、瞳収差の補正を有利に行うことができる。
【００７４】
また、第１正レンズ群と第３正レンズ群との間の光路中に所定の厚さの気体レンズを備えることにより可変絞り等により構成される開口絞りの配置位置の幅を大きくすることができ、可変絞り等を配置する際の設計自由度を大きくすることができる。一方、投影光学系が巨大化するのを防止することができる。
【００７５】
更に、第４レンズ群の第１正レンズ群、気体レンズ及び第３正レンズ群が全体として正の屈折力を有する群を構成することから、厚さの厚い気体レンズにより第１正レンズ群、気体レンズ及び第３正レンズ群の凸レンズ作用を軽減することができ、球面収差の発生を抑制することができる。
【００７６】
また、第１正レンズ群と第１負レンズ群との間の光路中に正の屈折力を有する第１気体レンズが配置され、第３正レンズ群と第２負レンズ群との間の光路中に正の屈折力を有する第２気体レンズが配置される、即ち、開口絞りに対して対称に正の屈折力を有する気体レンズが配置されるため、横収差の補正状態を保ちながら縦収差である球面収差の補正を優位に行うことができ、大開口数の投影光学系を実現することができる。
【００７７】
また、第４レンズ群中に蛍石により構成された正レンズを有することから、軸上色収差の補正を有利に行うことができる。
【００７８】
また、第２正レンズ群と第３レンズ群との間の光路中に第３負レンズ群が配置され、第４正レンズ群と第２面との間の光路中に第４負レンズ群が配置されているため、高次球面収差の補正を有利に行うことができる。
【００７９】
また、第１レンズ群及び第３レンズ群の少なくとも一方のレンズ群が非球面形状のレンズ面を備えるため、コマ収差、歪曲収差等、画角によって異なる高次収差の補正を有利に行うことができる。
【００８０】
また、この発明の露光装置によれば、投影光学系が大開口数を有し且つ、収差補正が良好に行われていることから、最小線幅の小さい露光パターンの露光を良好に行うことができる。
【００８１】
また、この発明の露光方法によれば、露光装置の投影光学系が大開口数を有し且つ、収差補正が良好に行われていることから、最小線幅の小さい露光パターンの露光を良好に行うことができる。
【図面の簡単な説明】
【図１】この発明の実施の形態にかかる投影光学系を備えた投影露光装置の構成を示す図である。
【図２】この発明の第１の実施例にかかる投影光学系のレンズ構成を示す図である。
【図３】この発明の第１の実施例にかかる投影光学系の縦収差を示す図である。
【図４】この発明の第１の実施例にかかる投影光学系の横収差を示す図である。
【図５】この発明の第２の実施例にかかる投影光学系のレンズ構成を示す図である。
【図６】この発明の第２の実施例にかかる投影光学系の縦収差を示す図である。
【図７】この発明の第２の実施例にかかる投影光学系の横収差を示す図である。
【図８】この発明の各実施例にかかる投影光学系を用いた半導体デバイスの製造方法を示すフローチャートである。
【図９】この発明の各実施例にかかる投影光学系を用いた半導体デバイスの製造方法を示すフローチャートである。
【符号の説明】
ＩＳ…照明光学装置、Ｒ…レチクル、ＲＳ…レチクルステージ、ＰＬ…投影光学系、ＡＳ…開口絞り、Ｗ…ウエハ、ＷＳ…ウエハステージ、Ｇ１…第１レンズ群、Ｇ２…第２レンズ群、Ｇ３…第３レンズ群、Ｇ４…第４レンズ群、Ｌ１４０４，Ｌ２４０４…第１正レンズ群、（Ｌ１４０１，Ｌ１４０２），（Ｌ２４０１，Ｌ２４０２）…第２正レンズ群、Ｌ１４０５，Ｌ２４０５…第３正レンズ群、（Ｌ１４０７，Ｌ１４０８，Ｌ１４０９），（Ｌ２４０７，Ｌ２４０８，Ｌ２４０９）…第４正レンズ群、Ｌ１４０３，Ｌ２４０３…第１負レンズ群、Ｌ１４０６，Ｌ２４０６…第２負レンズ群、Ｌ１３０４，Ｌ２３０４…第３負レンズ群、Ｌ１４１０，Ｌ２４１０…第４負レンズ群。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a projection optical system for projecting an image of a pattern on a first surface onto a second surface, a projection optical system including the projection optical system, and a reticle during a lithography process for manufacturing a semiconductor device, a liquid crystal display device, and the like. The present invention relates to an exposure apparatus used for transferring a pattern onto a substrate, and an exposure method using the exposure apparatus.
[0002]
[Prior art]
When manufacturing a semiconductor device or the like, a batch exposure type projection exposure apparatus (stepper) that transfers an image of a reticle pattern as a mask onto a wafer (or a glass plate or the like) coated with a resist via a projection optical system through a projection optical system. And the like, and a scanning exposure type projection exposure apparatus such as a step-and-scan method is used. As the patterns of semiconductor integrated circuits and the like have become finer, it has been particularly desired to improve the resolving power of a projection optical system provided in such an exposure apparatus. In order to improve the resolution of the projection optical system, it is conceivable to shorten the exposure wavelength or increase the numerical aperture (NA).
[0003]
Therefore, in recent years, from the g-line (wavelength 436 nm) of a mercury lamp to the i-line (wavelength 365 nm), exposure light has recently been used, and more recently, exposure light having a shorter wavelength, for example, KrF (wavelength). 248 nm), and an excimer laser beam such as ArF (wavelength 193 nm) is used. Then, a projection optical system that can be used under these short-wavelength exposure light has been developed (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2000-171699
[0005]
[Problems to be solved by the invention]
However, in the projection optical system disclosed in Patent Document 1 described above, the maximum numerical aperture is 0.80, and in a projection optical system in which further improvement in resolution is desired, a sufficiently large aperture is required. The number was not realized.
[0006]
An object of the present invention is to provide a projection optical system having a high numerical aperture and capable of reducing the minimum line width of an exposure pattern. Another object of the present invention is to provide an exposure apparatus having the projection optical system and an exposure method using the exposure apparatus.
[0007]
[Means for Solving the Problems]
The projection optical system according to claim 1, wherein in the projection optical system that forms an image of a first surface on a second surface, at least the lens group in the projection optical system is disposed closest to the first surface, and A first lens group having two negative lenses and having a negative refractive power, and a positive lens disposed in an optical path between the first lens group and the second surface, including at least three positive lenses; A second lens group having a refractive power, a third lens group disposed in an optical path between the second lens group and the second surface, including at least two biconcave lenses, and having a negative refractive power; A fourth lens group disposed in an optical path between the third lens group and the second surface, the fourth lens group including an aperture stop and having a positive refractive power. The fourth lens group includes the aperture stop. Is disposed adjacent to the first surface side and has one or more positive lenses and includes a negative lens. A first positive lens group, a first negative lens group disposed adjacent to the first surface side of the first positive lens group, the first negative lens group having one or more negative lenses and not including a positive lens; A second positive lens group disposed adjacent to the first surface side of one negative lens group and having at least one positive lens and not including a negative lens; and a second positive lens group adjacent to the second surface side of the aperture stop. A third positive lens group having at least one positive lens and not including a negative lens, and one or more negative lenses disposed adjacent to the second surface side of the third positive lens group. A second negative lens group having no positive lens and a fourth negative lens group disposed adjacent to the second surface side of the second negative lens group and having one or more positive lenses and no negative lens. And a positive lens group.
[0008]
According to the projection optical system of the first aspect, in the fourth lens group, the lens groups are arranged such that the refractive power is symmetric with respect to the aperture stop. That is, a first positive lens group adjacent to the first surface side of the aperture stop, a first negative lens group adjacent to the first surface side of the first positive lens group, and a first negative lens group adjacent to the first surface side of the first negative lens group. A second positive lens unit is disposed adjacent to the third stop, and a third positive lens unit is disposed adjacent to the second surface of the aperture stop, and a second negative lens unit is disposed adjacent to the second surface of the third positive lens unit. A fourth positive lens group is disposed adjacent to the second surface of the second negative lens group. Accordingly, it is possible to advantageously correct lateral aberration such as coma aberration, distortion, and chromatic aberration of magnification. Further, since the negative lens group is arranged on the second surface side of the aperture stop, the Petzval sum between the aperture stop and the second surface can be easily corrected, and the correction of pupil aberration is advantageous. Can be done.
[0009]
The projection optical system according to claim 2 is a projection optical system that forms an image of a first surface on a second surface, wherein the projection optical system is disposed in an optical path between the first surface and the second surface, and A first lens group having two negative lenses and having a negative refractive power, and a positive lens disposed in an optical path between the first lens group and the second surface, including at least three positive lenses; A second lens group having a refractive power, a third lens group disposed in an optical path between the second lens group and the second surface, including at least two biconcave lenses, and having a negative refractive power; A fourth lens group disposed in an optical path between the third lens group and the second surface, the fourth lens group including an aperture stop and having a positive refractive power. The fourth lens group includes the aperture stop. The one that is disposed adjacent to the first surface side and has one or more positive lenses and does not include a negative lens A positive lens group, a first negative lens group disposed adjacent to the first surface side of the first positive lens group and having one or more negative lenses and not including a positive lens, and the first negative lens A second positive lens group disposed adjacent to the first surface side of the group and having one or more positive lenses and not including a negative lens; and a second positive lens group disposed adjacent to the second surface side of the aperture stop. A third positive lens group that has one or more positive lenses and does not include a negative lens, and is disposed adjacent to the second surface side of the third positive lens group, and has one or more negative lenses; A second negative lens group that does not include a positive lens; and a fourth positive lens group that is disposed adjacent to the second surface of the second negative lens group and that has one or more positive lenses and does not include a negative lens. And a gas lens disposed in an optical path between the first positive lens group and the third positive lens group. The axial thickness of the gas lens is D1, when the length of the projection optical system is L,
0.02 <(D1 / L) <0.2
The following condition is satisfied.
[0010]
According to the projection optical system of the second aspect, in the fourth lens group, since the lens groups are arranged such that the refractive power is symmetric with respect to the aperture stop, coma aberration, which is lateral aberration, Correction of distortion and furthermore, chromatic aberration of magnification can be advantageously performed. Further, since the negative lens group is arranged on the second surface side of the aperture stop, the Petzval sum between the aperture stop and the second surface can be easily corrected, and the correction of pupil aberration is advantageous. Can be done.
[0011]
By providing a thick gas lens in the optical path between the first positive lens group and the third positive lens group, that is, by satisfying the condition of 0.02 <(D1 / L), The width of the arrangement position of the aperture stop constituted by the stop and the like can be increased, and the degree of freedom in designing the arrangement of the variable stop mechanism and the like can be increased. On the other hand, by satisfying the condition of (D1 / L) <0.2, it is possible to prevent the projection optical system from being enlarged.
[0012]
Further, since the first positive lens group, the gas lens, and the third positive lens group of the fourth lens group constitute a group having a positive refractive power as a whole, the first positive lens group includes a thick gas lens. The convex lens action of the gas lens and the third positive lens group can be reduced, and the occurrence of spherical aberration can be reduced. Accordingly, since the generation of spherical aberration is suppressed in the fourth lens group having a positive refractive power, the positive refractive power of the second lens group can be reduced, and the fourth lens group has The refractive power of the lens can be reduced.
[0013]
The projection optical system according to claim 3 is a projection optical system that forms an image of a first surface on a second surface, wherein the projection optical system is disposed in an optical path between the first surface and the second surface, and A first lens group having two negative lenses and having a negative refractive power, and a positive lens disposed in an optical path between the first lens group and the second surface, including at least three positive lenses; A second lens group having a refractive power, a third lens group disposed in an optical path between the second lens group and the second surface, including at least two biconcave lenses, and having a negative refractive power; A fourth lens group disposed in an optical path between the third lens group and the second surface, the fourth lens group including an aperture stop and having a positive refractive power. The fourth lens group includes the aperture stop. The one that is disposed adjacent to the first surface side and has one or more positive lenses and does not include a negative lens A positive lens group, a first negative lens group disposed adjacent to the first surface side of the first positive lens group and having one or more negative lenses and not including a positive lens, and the first negative lens A second positive lens group disposed adjacent to the first surface side of the group and having one or more positive lenses and not including a negative lens; and a second positive lens group disposed adjacent to the second surface side of the aperture stop. A third positive lens group that has one or more positive lenses and does not include a negative lens, and is disposed adjacent to the second surface side of the third positive lens group, and has one or more negative lenses; A second negative lens group that does not include a positive lens; and a fourth positive lens group that is disposed adjacent to the second surface of the second negative lens group and that has one or more positive lenses and does not include a negative lens. A first positive lens disposed in an optical path between the first positive lens group and the first negative lens group and having a positive refractive power; And body lens, characterized by comprising a third is arranged in the optical path between the positive lens group and the second negative lens group second gas lens having a positive refractive power.
[0014]
According to the projection optical system of the third aspect, in the fourth lens group, since the lens groups are arranged such that the refractive power is symmetric with respect to the aperture stop, coma aberration, which is lateral aberration, Correction of distortion and furthermore, chromatic aberration of magnification can be advantageously performed. Further, since the negative lens group is arranged on the second surface side of the aperture stop, the Petzval sum between the aperture stop and the second surface can be easily corrected, and the correction of pupil aberration is advantageous. Can be done.
[0015]
A first gas lens having a positive refractive power is disposed in an optical path between the first positive lens group and the first negative lens group, and an optical path between the third positive lens group and the second negative lens group. Since a second gas lens having a positive refractive power is disposed therein, that is, a gas lens having a positive refractive power is disposed symmetrically with respect to the aperture stop, the longitudinal aberration is maintained while the lateral aberration is corrected. Can be advantageously corrected, and a projection optical system having a large numerical aperture can be realized.
[0016]
The projection optical system according to claim 4, wherein the fourth lens group includes a gas lens disposed between the first positive lens group and the third positive lens group, and the thickness of the gas lens on the axis. Let D1 be the length and L be the total length of the projection optical system,
0.02 <(D1 / L) <0.2
The following condition is satisfied.
[0017]
According to the projection optical system of the fourth aspect, by providing a thick gas lens in the optical path between the first positive lens group and the third positive lens group, that is, 0.02 <(D1 / By satisfying the condition (L), it is possible to increase the width of the arrangement position of the aperture stop constituted by the variable stop and the like, thereby increasing the degree of freedom in designing the variable stop mechanism and the like. On the other hand, by satisfying the condition of (D1 / L) <0.2, it is possible to prevent the projection optical system from being enlarged.
[0018]
Further, since the first positive lens group, the gas lens, and the third positive lens group of the fourth lens group constitute a group having a positive refractive power as a whole, the first positive lens group includes a thick gas lens. The convex lens action of the gas lens and the third positive lens group can be reduced, and the occurrence of spherical aberration can be reduced. Accordingly, since the generation of spherical aberration is suppressed in the fourth lens group having a positive refractive power, the positive refractive power of the second lens group can be reduced, and the fourth lens group has The refractive power of the lens can be reduced.
[0019]
In a projection optical system according to a fifth aspect, the fourth lens group is disposed in an optical path between the first positive lens group and the first negative lens group and has a first refractive power. A gas lens; and a second gas lens disposed in an optical path between the third positive lens group and the second negative lens group and having a positive refractive power.
[0020]
According to the projection optical system of the fifth aspect, the first gas lens having a positive refractive power is disposed in the optical path between the first positive lens group and the first negative lens group, and the third positive lens group A second gas lens having a positive refractive power is disposed in the optical path between the first lens unit and the second negative lens group, that is, a gas lens having a positive refractive power is disposed symmetrically with respect to the aperture stop. In addition, spherical aberration, which is longitudinal aberration, can be advantageously corrected while maintaining the state of correcting lateral aberration, and a projection optical system having a large numerical aperture can be realized.
[0021]
The projection optical system according to claim 6 is characterized in that at least one positive lens in the fourth lens group is made of fluorite. According to the projection optical system of the sixth aspect, since the projection optical system includes the positive lens made of fluorite, axial chromatic aberration can be advantageously corrected.
[0022]
The projection optical system according to claim 7, wherein the fourth lens group is disposed in an optical path between the second positive lens group and the third lens group, and has one or more negative lenses. A third negative lens group that does not include a positive lens, and a third negative lens group that is disposed in an optical path between the fourth positive lens group and the second surface, has one or more negative lenses, and does not include a positive lens. A fourth negative lens group, wherein at least one lens constituting the third negative lens group has a lens surface on the aperture stop side concave toward the second surface side to constitute the fourth negative lens group. The surface on the aperture stop side of one lens has a concave surface facing the first surface side.
[0023]
According to the projection optical system of the seventh aspect, the third negative lens group is disposed in the optical path between the second positive lens group and the third lens group, and the fourth positive lens group and the second surface are connected to each other. Since the fourth negative lens group is disposed in the optical path between the lenses, it is possible to advantageously correct higher-order spherical aberration.
[0024]
In a projection optical system according to an eighth aspect, at least one of the first lens group and the third lens group has an aspherical lens surface. According to the projection optical system of the present invention, at least one of the first lens group and the third lens group has an aspherical lens surface, and thus varies depending on the angle of view such as coma aberration and distortion. Higher order aberrations can be advantageously corrected.
[0025]
An exposure apparatus according to a ninth aspect includes the projection optical system according to any one of the first to eighth aspects, and an illumination optical system that illuminates a reticle disposed on the first surface. An image of the reticle pattern is projected onto a substrate disposed on the second surface via the projection optical system by exposure light from the illumination optical system.
[0026]
According to the exposure apparatus of the ninth aspect, since the projection optical system has a large numerical aperture and the aberration correction is performed well, it is possible to satisfactorily perform exposure of an exposure pattern having a small minimum line width. Can be.
[0027]
An exposure method according to a tenth aspect provides an illumination step of illuminating a reticle disposed on the first surface using the illumination optical system according to any one of the first to eighth aspects. An exposure step of transferring a pattern onto a substrate arranged on the second surface.
[0028]
According to the exposure method of the tenth aspect, since the projection optical system of the exposure apparatus has a large numerical aperture and satisfactorily performs aberration correction, the exposure of an exposure pattern having a small minimum line width is excellent. Can be done.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating a configuration of a projection exposure apparatus including a projection optical system.
[0030]
As shown in FIG. 1, a reticle R is disposed as a projection original on which a predetermined circuit pattern is formed on an object plane (first plane) of the projection optical system PL, and an image plane (second plane) of the projection optical system PL is provided. Is provided with a wafer W coated with a photoresist as a substrate. Reticle R is held on reticle stage RS, and wafer W is held on wafer stage WS. An illumination optical device IS for uniformly illuminating the reticle R is disposed above the reticle R.
[0031]
The projection optical system PL has a variable aperture stop AS near the pupil position, and is substantially telecentric on the reticle R side and on the wafer W side. The illumination optical device IS includes a fly-eye lens for uniformizing the illuminance distribution of the exposure light, an illumination system aperture stop, a variable field stop (reticle blind), a condenser lens system, and the like. The exposure light supplied from the illumination optical device IS illuminates the reticle R, an image of the light source in the illumination optical device IS is formed at the pupil position of the projection optical system PL, and so-called Koehler illumination is performed. Then, the pattern image of the reticle R illuminated by Koehler illumination is reduced at the projection magnification via the projection optical system PL and is exposed (transferred) onto the wafer W.
[0032]
FIG. 2 is a lens cross-sectional view of the projection optical system according to the first example. The projection optical system PL has a negative refractive power composed of a negative meniscus lens L1101 having a convex surface facing the reticle side and a negative meniscus lens L1102 having a concave surface facing the reticle side from the reticle R side as the first object. A first lens group G1, a second meniscus lens G2 having a positive refractive power, composed of a positive meniscus lens L1201, L1202 having a concave surface facing the reticle side, and a biconvex lens L1203, L1204, L1205, L1206, and a biconcave lens L1301, L1302. , L1303, a third lens group G3 having a negative refractive power, composed of a biconcave lens L (third negative lens group) L1304, a biconvex lens (second positive lens group) L1401, and a positive meniscus having a concave surface facing the reticle side. Lens (second positive lens unit) L1402, negative lens with concave surface facing reticle side A varnish lens (first negative lens group) L1403, a biconvex lens (first positive lens group) L1404, a positive meniscus lens (third positive lens group) L1405 with a concave surface facing the reticle side, a plano-concave lens with a concave surface facing the reticle side ( A second negative lens unit) L1406, a positive meniscus lens (fourth positive lens unit) L1407 having a convex surface facing the reticle side, a positive meniscus lens (a fourth positive lens unit) L1408 having a convex surface facing the reticle side, and a convex surface facing the reticle side , A positive meniscus lens (fourth positive lens group) L1409, a biconcave lens (fourth negative lens group) L1410, a positive meniscus lens L1411 with a convex surface facing the reticle side, and a plano-convex lens L1412 with a convex surface facing the reticle side. And a fourth lens group G4 (G1 to G4) having a positive refractive power. .
[0033]
An aperture stop AS is arranged between the biconvex lens L1404 and the positive meniscus lens L1405. Further, the first positive lens group, the second positive lens group, the third positive lens group, and the fourth positive lens group are lens groups that have one or more positive lenses and do not include a negative lens. The group, the second negative lens group, the third negative lens group, and the fourth negative lens group are lens groups that have one or more negative lenses and do not include a positive lens.
[0034]
According to this projection optical system, in the fourth lens group G4, the lens groups are arranged such that the refractive power is symmetric with respect to the aperture stop AS. That is, the first positive lens unit L1404 is adjacent to the reticle R side of the aperture stop AS, the first negative lens unit L1403 is adjacent to the reticle R side of the first positive lens unit L1404, and the reticle R of the first negative lens unit L1403. The second positive lens units L1401 and L1402 are disposed adjacent to the side, and adjacent to the wafer W side of the aperture stop AS and adjacent to the wafer W side of the third positive lens unit L1405. A fourth positive lens group 1407, L1408, and L1409 are disposed adjacent to the second negative lens group 1406 and the wafer W side of the second negative lens group 1406. Accordingly, it is possible to advantageously correct lateral coma, distortion, and chromatic aberration of magnification. Further, since the negative lens group is arranged on the wafer W side of the aperture stop AS, the Petzval sum between the aperture stop and the wafer W can be easily corrected, and the correction of the pupil aberration is advantageously performed. It can be carried out.
[0035]
This projection optical system includes a gas lens in which the fourth lens group G4 is disposed between the first positive lens group L1404 and the third positive lens group L1405. When the axial thickness of this gas lens is D1 and the total length of the projection optical system is L,
0.02 <(D1 / L) <0.2
Satisfies the condition.
[0036]
According to this projection optical system, a thick gas lens is provided in the optical path between the first positive lens unit L1404 and the third positive lens unit L1405, that is, 0.02 <(D1 / L). By satisfying the condition, it is possible to increase the width of the arrangement position of the aperture stop constituted by the variable stop and the like, and to increase the degree of freedom in designing the variable stop mechanism and the like. On the other hand, by satisfying the condition of (D1 / L) <0.2, it is possible to prevent the projection optical system from being enlarged.
[0037]
Further, since the first positive lens unit L1404, the gas lens, and the third positive lens unit L1405 of the fourth lens unit G4 constitute a group having a positive refractive power as a whole, the first positive lens unit is formed by a thick gas lens. The convex lens action of the lens group, the gas lens, and the third positive lens group can be reduced, and the occurrence of spherical aberration can be reduced. Accordingly, since the generation of spherical aberration is suppressed in the fourth lens group having a positive refractive power, the positive refractive power of the second lens group can be reduced, and the fourth lens group has The refractive power of the lens can be reduced.
[0038]
In this projection optical system, the fourth lens group G4 is disposed in the optical path between the first positive lens group L1404 and the first negative lens group L1403, and has a gas lens having a positive refractive power (a first gas lens). ) And a gas lens (second gas lens) having a positive refractive power and disposed in the optical path between the third positive lens unit L1405 and the second negative lens unit L1406. That is, since the gas lens having a positive refractive power is disposed symmetrically with respect to the aperture stop, it is possible to perform the correction of the spherical aberration, which is the longitudinal aberration, while maintaining the correction state of the lateral aberration, and to obtain a large numerical aperture. Projection optical system can be realized.
[0039]
In this projection optical system, the lens constituting the projection optical system is a synthetic quartz (SiO 2) having a glass material refractive index n = 1.560326 at the wavelength of an ArF excimer laser (wavelength λ = 193 nm). ₂ ) Or fluorite (CaF) having a glass material refractive index n = 1.501455 at the wavelength of an ArF excimer laser (wavelength λ = 193 nm). ₂ ). In the fourth lens group G4, a positive meniscus lens L1402, a positive meniscus lens L1411, and a plano-convex lens L1412 having a convex surface facing the reticle side are formed of fluorite. Since the fourth lens group G4 includes a positive lens made of fluorite, it is possible to advantageously correct axial chromatic aberration. In this projection optical system, the biconvex lens L1206 in the second lens group G2 and the positive meniscus lens L1402 in the fourth lens group G4 with the concave surface facing the reticle side are also formed of fluorite.
[0040]
In this projection optical system, a third negative lens unit L1304 is arranged in the optical path between the second positive lens units L1401, L1402 and the third lens unit G3, and the fourth positive lens units L1407, L1408, L1409 Since the fourth negative lens unit L1410 is arranged in the optical path between the optical system and the wafer W, the higher-order spherical aberration can be advantageously corrected.
[0041]
Further, the projection optical system PL is configured to have aspherical surfaces ASP1 to ASP8. That is, in the first lens group G1, the lens surface on the wafer W side of the negative meniscus lens L1101 is configured as an aspherical surface ASP1, and the lens surface on the reticle R side of the negative meniscus lens L1102 is configured as an aspherical surface ASP2. In the third lens group G3, the lens surface on the wafer W side of the biconcave lens L1301 is configured as an aspheric ASP3, and the lens surface on the reticle R side of the biconcave lens L1302 is configured as an aspheric ASP4. The lens surface on the wafer W side of L1303 is configured as an aspherical ASP5, and the lens surface on the wafer W side of the biconcave lens L1304 is configured as an aspherical ASP6. In the fourth lens group G4, the lens surface on the wafer W side of the positive meniscus lens L1409 is configured as an aspherical ASP7, and the lens surface on the wafer W side of the biconcave lens L1410 is configured as an aspherical ASP8. According to this projection optical system, since at least one of the first lens group G1 and the third lens group G3 has an aspherical lens surface, high-order aberrations such as coma and distortion that vary depending on the angle of view. Can be advantageously corrected.
[0042]
Next, Table 1 shows specification values of the projection optical system according to the first example. Here, design specifications of the projection optical system are shown below.
Numerical aperture (NA) = 0.85
Exposure field = 26 × 8 (mm)
Imaging magnification = 1 / 4x
Object-optical system distance: 53.88146 (mm)
Image-optical system distance: 19.1157 (mm)
Projection optical system overall length (L): 1250 (mm)
In Table 1, the surface number is the order of the lens surfaces from the reticle R side, r is the radius of curvature of the corresponding lens surface, d is the interval on the optical axis from the relevant lens surface to the next lens surface, and the effective diameter is each lens surface. And n indicate the refractive index of the glass material at the wavelength of the ArF excimer laser (wavelength λ = 193 nm).
[0043]
[Table 1]

[0044]
Table 2 shows coefficients representing the aspherical shape. Here, the aspherical shape is defined by the following Equation 1.
[0045]
(Equation 1)

[0046]
Here, Z is the sag amount, h is the distance from the optical axis, r is the radius of curvature of the vertex of the surface, and k is the cone coefficient (when k = 0, the spherical surface).
[0047]
[Table 2]

[0048]
Next, values (condition corresponding values) corresponding to the conditional expressions according to the first embodiment are shown.
D1 = 122.271
L = 1250
D1 / L = 0.098
FIG. 3 shows longitudinal aberrations of the projection optical system according to the first embodiment, and FIG. 4 shows lateral aberrations (coma aberrations) in the meridional direction (tangential direction) and the spherical missing direction (sagittal direction). I have. In each aberration diagram, N.I. A. Indicates the numerical aperture of the projection optical system PL on the wafer W side, and field height indicates the image height on the wafer W side. The image plane (sagittal image plane) is shown.
[0049]
In the projection optical system according to the first embodiment, that is, in the projection optical system having the high numerical aperture, it can be understood that spherical aberration, distortion (distortion), coma, and the like are corrected in a well-balanced manner.
[0050]
Next, the configuration of a projection optical system according to a second embodiment will be described. FIG. 5 is a lens cross-sectional view of the projection optical system according to the second example. The projection optical system PL includes, from a reticle R side as a first object, a first lens group G1 having negative refracting power constituted by biconcave lenses L2101 and L2102, biconvex lenses L2201, L2202 and L2203, and a convex surface on the reticle side. , A negative meniscus lens L2204, a biconvex lens L2205, a second lens group G2 having a positive refractive power, a biconcave lens L2301, L2302, L2303, and a biconcave lens (third negative lens group) L2304. A third meniscus lens (second positive lens group) L2401 having a concave surface facing the reticle side, a positive meniscus lens (second positive lens group) L2402 having a concave surface facing the reticle side, and a reticle. Meniscus lens (first negative lens unit) L2403 with the concave surface facing the side A positive meniscus lens (first positive lens group) L2404 with a concave surface facing the reticle side, a positive meniscus lens (third positive lens group) L2405 with a concave surface facing the reticle side, and a plano-concave lens (second positive lens surface) facing the reticle side A negative meniscus lens L2406, a positive meniscus lens (fourth positive lens group) L2407 with a concave surface facing the reticle side, a positive meniscus lens (fourth positive lens group) L2408 with a convex surface facing the reticle side, and a convex surface facing the reticle side A positive meniscus lens (fourth positive lens group) L2409, a biconcave lens (fourth negative lens group) L2410, a positive meniscus lens L2411 having a convex surface facing the reticle side, and a plano-convex lens L2412 having a convex surface facing the reticle side. The fourth lens group G4 (G1 to G4) having a positive refractive power is configured.
[0051]
Note that an aperture stop AS is arranged between the positive meniscus lens L2404 and the positive meniscus lens L2405. Further, the first positive lens group, the second positive lens group, the third positive lens group, and the fourth positive lens group are lens groups that have one or more positive lenses and do not include a negative lens. The group, the second negative lens group, the third negative lens group, and the fourth negative lens group are lens groups that have one or more negative lenses and do not include a positive lens.
[0052]
According to this projection optical system, in the fourth lens group G4, the lens groups are arranged such that the refractive power is symmetric with respect to the aperture stop AS. That is, the reticle R of the first positive lens unit L2404 adjacent to the reticle R side of the aperture stop AS, the first negative lens unit L2403, and the reticle R of the first negative lens unit L2403 adjacent to the reticle R side of the first positive lens unit L2404. The second positive lens groups L2401 and L2402 are arranged adjacent to the side, and the third positive lens group L2405 adjacent to the wafer W side of the aperture stop AS and the wafer W side adjacent to the third positive lens group L2405. A fourth positive lens group 2407, L2408, and L2409 are arranged adjacent to the second negative lens group 2406 and the wafer W side of the second negative lens group 2406. Accordingly, it is possible to advantageously correct lateral coma, distortion, and chromatic aberration of magnification. Further, since the negative lens group is arranged on the wafer W side of the aperture stop AS, the Petzval sum between the aperture stop and the wafer W can be easily corrected, and the correction of the pupil aberration is advantageously performed. It can be carried out.
[0053]
This projection optical system includes a gas lens in which the fourth lens group G4 is disposed between the first positive lens group L2404 and the third positive lens group L2405. When the axial thickness of this gas lens is D1 and the total length of the projection optical system is L,
0.02 <(D1 / L) <0.2
Satisfies the condition.
[0054]
According to this projection optical system, a thick gas lens is provided in the optical path between the first positive lens unit L2404 and the third positive lens unit L2405, that is, 0.02 <(D1 / L). By satisfying the condition, it is possible to increase the width of the arrangement position of the aperture stop constituted by the variable stop and the like, and to increase the degree of freedom in designing the variable stop mechanism and the like. On the other hand, by satisfying the condition of (D1 / L) <0.2, it is possible to prevent the projection optical system from being enlarged.
[0055]
Further, since the first positive lens unit L2404, the gas lens, and the third positive lens unit L2405 of the fourth lens unit G4 constitute a group having a positive refractive power as a whole, the first positive lens unit is formed by a thick gas lens. The convex lens action of the lens group, the gas lens, and the third positive lens group can be reduced, and the occurrence of spherical aberration can be reduced. Accordingly, since the generation of spherical aberration is suppressed in the fourth lens group having a positive refractive power, the positive refractive power of the second lens group can be reduced, and the fourth lens group has The refractive power of the lens can be reduced.
[0056]
In this projection optical system, the fourth lens group G4 is disposed in the optical path between the first positive lens group L2404 and the first negative lens group L2403, and the gas lens having the positive refractive power (the first gas lens) ) And a gas lens (second gas lens) disposed in the optical path between the third positive lens unit L2405 and the second negative lens unit L2406 and having a positive refractive power. That is, since the gas lens having a positive refractive power is disposed symmetrically with respect to the aperture stop, it is possible to advantageously correct the spherical aberration, which is the longitudinal aberration, while maintaining the correction state of the lateral aberration, and to increase the large numerical aperture. Projection optical system can be realized.
[0057]
In this projection optical system, the lens constituting the projection optical system is a synthetic quartz (SiO 2) having a glass material refractive index n = 1.560326 at the wavelength of an ArF excimer laser (wavelength λ = 193 nm). ₂ ) Or fluorite (CaF) having a glass material refractive index n = 1.501455 at the wavelength of an ArF excimer laser (wavelength λ = 193 nm). ₂ ). In the fourth lens group G4, a positive meniscus lens L2411, and a plano-convex lens L2412 having a convex surface facing the reticle side are formed of fluorite. Since the fourth lens group G4 includes a positive lens made of fluorite, it is possible to advantageously correct axial chromatic aberration.
[0058]
In this projection optical system, a third negative lens group L2304 is disposed in the optical path between the second positive lens groups L2401, L2402 and the third lens group G3, and the fourth positive lens groups L2407, L2408, L2409 Since the fourth negative lens unit L2410 is arranged in the optical path between the second negative lens unit L2410 and the wafer W, high-order spherical aberration can be advantageously corrected.
[0059]
Further, the projection optical system PL is configured to have aspherical surfaces ASP1 to ASP8. That is, in the first lens group G1, the lens surface on the wafer W side of the biconcave lens L2101 is configured as an aspherical ASP1, and the lens surface on the reticle R side of the biconcave lens L2102 is configured as an aspherical ASP2. In the third lens group G3, the lens surface on the wafer W side of the biconcave lens L2301 is configured as an aspherical ASP3, and the lens surface on the reticle R side of the biconcave lens L2302 is configured as an aspherical ASP4. The lens surface on the wafer W side of L2303 is configured as an aspherical ASP5, and the lens surface on the wafer W side of the biconcave lens L2304 is configured as an aspherical ASP6. In the fourth lens group G4, the lens surface on the wafer W side of the positive meniscus lens L2409 is configured as an aspherical ASP7, and the lens surface on the wafer W side of the biconcave lens L1410 is configured as an aspherical ASP8. According to this projection optical system, since at least one of the first lens group G1 and the third lens group G3 has an aspherical lens surface, high-order aberrations such as coma and distortion that vary depending on the angle of view. Can be advantageously corrected.
[0060]
Next, Table 3 shows the specification values of the projection optical system according to the second example. Here, design specifications of the projection optical system are shown below.
Numerical aperture (NA) = 0.85
Exposure field = 26 × 8 (mm)
Imaging magnification = 1 / 4x
Object-optical distance: 58.90558 (mm)
Image-optical system distance: 11.59551 (mm)
Projection optical system overall length (L): 1250 (mm)
In Table 3, the surface number is the order of the lens surfaces from the reticle R side, r is the radius of curvature of the corresponding lens surface, d is the interval on the optical axis from the relevant lens surface to the next lens surface, and the effective diameter is each lens surface. And n indicate the refractive index of the glass material at the wavelength of the ArF excimer laser (wavelength λ = 193 nm).
[0061]
[Table 3]

[0062]
Table 4 shows coefficients representing the aspherical shape. Here, the aspherical shape is defined by the above-described formula 1.
[0063]
[Table 4]

[0064]
Next, values (condition corresponding values) corresponding to the conditional expressions according to the second embodiment are shown.
D1 = 88.47547
L = 1250
D1 / L = 0.071
FIG. 6 shows the longitudinal aberration of the projection optical system according to the second example, and FIG. 7 shows the transverse aberration (coma aberration) in the meridional direction (tangential direction) and the missing spherical direction (sagittal direction). I have. In each aberration diagram, N.I. A. Indicates the numerical aperture of the projection optical system PL on the wafer W side, and field height indicates the image height on the wafer W side. The image plane (sagittal image plane) is shown.
[0065]
It can be understood that in the projection optical system according to the second embodiment, that is, the projection optical system having the high numerical aperture, spherical aberration, distortion (distortion), coma, and the like are corrected in a well-balanced manner.
[0066]
In the above-described embodiment, an example in which ArF excimer laser light is used as the exposure light has been described. However, the present invention is not limited to this, and KrF excimer laser light, a g-line of a mercury lamp, an i-line Needless to say, the present invention can be applied to the case where light of other wavelengths is used.
[0067]
In the exposure apparatus according to the above-described embodiment, the reticle (mask) is illuminated by the illumination optical device (illumination step), and the transfer pattern formed on the mask is exposed on the photosensitive substrate using the projection optical system ( By the exposure step, a micro device (semiconductor element, image pickup element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. Hereinafter, a method of manufacturing a semiconductor device for obtaining a semiconductor device as a microdevice by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the embodiment shown in FIG. This will be described with reference to a flowchart.
[0068]
First, in step 301 of FIG. 8, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied on the metal film on the wafer of the lot. Thereafter, in step 303, using the exposure apparatus shown in FIG. 1, the image of the pattern on the mask is sequentially exposed and transferred to each shot area on the one lot of wafers via the projection optical system. That is, the mask is illuminated by the illumination optical device (illumination step), and the pattern of the mask is transferred onto the wafer (exposure step).
[0069]
Thereafter, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist on the one lot of wafers is etched using the resist pattern as a mask to form a pattern on the mask. A corresponding circuit pattern is formed in each shot area on each wafer. Thereafter, a device such as a semiconductor element is manufactured by forming a circuit pattern of an upper layer and the like. According to the above-described semiconductor device manufacturing method, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput.
[0070]
In the exposure apparatus of the present embodiment shown in FIG. 1, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). it can. Hereinafter, a method of manufacturing a liquid crystal display element as a micro device will be described with reference to the flowchart of FIG. 9, in a pattern forming step 401, a so-called photolithography step of transferring and exposing a mask pattern to a photosensitive substrate (eg, a glass substrate coated with a resist) using the exposure apparatus shown in FIG. 1 is performed. By this photolithography step, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. After that, the exposed substrate undergoes various processes such as a developing process, an etching process, and a reticle peeling process, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming process 402.
[0071]
Next, in a color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix, or three R, G, B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter forming step 402, a cell assembling step 403 is performed. In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like. In the cell assembling step 403, for example, a liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern forming step 401 and the color filter obtained in the color filter forming step 402, and a liquid crystal panel (liquid crystal cell) is formed. ) To manufacture.
[0072]
Thereafter, in a module assembling step 404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display device, a liquid crystal display device having an extremely fine circuit pattern can be obtained with high throughput.
[0073]
【The invention's effect】
According to the projection optical system of the present invention, in the fourth positive lens group, since the lens groups are arranged such that the refractive power is symmetrical with respect to the aperture stop, coma aberration as a lateral aberration, distortion, Further, it is possible to advantageously correct lateral chromatic aberration. Further, since the negative lens group is arranged on the second surface side of the aperture stop, the Petzval sum between the aperture stop and the second surface can be easily corrected, and the correction of pupil aberration is advantageous. Can be done.
[0074]
Further, by providing a gas lens having a predetermined thickness in the optical path between the first positive lens group and the third positive lens group, it is possible to increase the width of the arrangement position of the aperture stop constituted by the variable stop or the like. Thus, the degree of freedom in designing a variable aperture or the like can be increased. On the other hand, it is possible to prevent the projection optical system from being enlarged.
[0075]
Further, since the first positive lens group, the gas lens, and the third positive lens group of the fourth lens group constitute a group having a positive refractive power as a whole, the first positive lens group includes a thick gas lens. The convex lens action of the gas lens and the third positive lens group can be reduced, and the occurrence of spherical aberration can be suppressed.
[0076]
A first gas lens having a positive refractive power is disposed in an optical path between the first positive lens group and the first negative lens group, and an optical path between the third positive lens group and the second negative lens group. Since a second gas lens having a positive refractive power is disposed therein, that is, a gas lens having a positive refractive power is disposed symmetrically with respect to the aperture stop, the longitudinal aberration is maintained while the lateral aberration is corrected. Correction of the spherical aberration can be performed advantageously, and a projection optical system having a large numerical aperture can be realized.
[0077]
Further, since the fourth lens group includes a positive lens made of fluorite, it is possible to advantageously correct axial chromatic aberration.
[0078]
Further, a third negative lens group is disposed in an optical path between the second positive lens group and the third lens group, and a fourth negative lens group is disposed in an optical path between the fourth positive lens group and the second surface. Since they are arranged, correction of higher-order spherical aberration can be advantageously performed.
[0079]
In addition, since at least one of the first lens group and the third lens group has an aspheric lens surface, it is possible to advantageously perform correction of high-order aberrations such as coma aberration and distortion that vary depending on the angle of view. it can.
[0080]
Further, according to the exposure apparatus of the present invention, since the projection optical system has a large numerical aperture and aberration correction is performed well, it is possible to perform exposure of an exposure pattern having a small minimum line width satisfactorily. it can.
[0081]
Further, according to the exposure method of the present invention, since the projection optical system of the exposure apparatus has a large numerical aperture and the aberration correction is performed well, the exposure of the exposure pattern having a small minimum line width can be performed well. It can be carried out.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a projection exposure apparatus including a projection optical system according to an embodiment of the present invention.
FIG. 2 is a diagram showing a lens configuration of a projection optical system according to a first embodiment of the present invention.
FIG. 3 is a diagram illustrating longitudinal aberration of the projection optical system according to the first example of the present invention.
FIG. 4 is a diagram showing lateral aberration of the projection optical system according to the first example of the present invention.
FIG. 5 is a diagram showing a lens configuration of a projection optical system according to a second embodiment of the present invention.
FIG. 6 is a diagram illustrating longitudinal aberration of a projection optical system according to a second example of the present invention.
FIG. 7 is a diagram showing a lateral aberration of a projection optical system according to a second example of the present invention.
FIG. 8 is a flowchart illustrating a method of manufacturing a semiconductor device using a projection optical system according to each embodiment of the present invention.
FIG. 9 is a flowchart illustrating a method of manufacturing a semiconductor device using a projection optical system according to each embodiment of the present invention.
[Explanation of symbols]
IS: illumination optical device, R: reticle, RS: reticle stage, PL: projection optical system, AS: aperture stop, W: wafer, WS: wafer stage, G1: first lens group, G2: second lens group, G3 .. Third lens group, G4 fourth lens group, L1404, L2404 first positive lens group, (L1401, L1402), (L2401, L2402) second positive lens group, L1405, L2405 third positive lens group , (L1407, L1408, L1409), (L2407, L2408, L2409) ... fourth positive lens group, L1403, L2403 ... first negative lens group, L1406, L2406 ... second negative lens group, L1304, L2304 ... third negative Lens groups, L1410, L2410... Fourth negative lens group.

Claims (10)

In a projection optical system that forms an image of a first surface on a second surface,
A first lens group that is disposed closest to the first surface side among the lens groups in the projection optical system, includes at least two negative lenses, and has a negative refractive power;
A second lens group disposed in an optical path between the first lens group and the second surface, the second lens group including at least three positive lenses and having a positive refractive power;
A third lens group disposed in an optical path between the second lens group and the second surface and including at least two biconcave lenses and having a negative refractive power;
A fourth lens group disposed in an optical path between the third lens group and the second surface and including an aperture stop and having a positive refractive power;
The fourth lens group includes:
A first positive lens group disposed adjacent to the first surface side of the aperture stop and having one or more positive lenses and not including a negative lens;
A first negative lens group disposed adjacent to the first surface side of the first positive lens group and having one or more negative lenses and not including a positive lens;
A second positive lens group disposed adjacent to the first surface side of the first negative lens group and having one or more positive lenses and not including a negative lens;
A third positive lens group disposed adjacent to the second surface side of the aperture stop and having one or more positive lenses and not including a negative lens;
A second negative lens group disposed adjacent to the second surface side of the third positive lens group and having one or more negative lenses and not including a positive lens;
A fourth positive lens group disposed adjacent to the second surface side of the second negative lens group and having one or more positive lenses and not including a negative lens;
A projection optical system comprising: In a projection optical system that forms an image of a first surface on a second surface,
A first lens group disposed in an optical path between the first surface and the second surface and including at least two negative lenses and having a negative refractive power;
A second lens group disposed in an optical path between the first lens group and the second surface, the second lens group including at least three positive lenses and having a positive refractive power;
A third lens group disposed in an optical path between the second lens group and the second surface and including at least two biconcave lenses and having a negative refractive power;
A fourth lens group disposed in an optical path between the third lens group and the second surface and including an aperture stop and having a positive refractive power;
The fourth lens group includes:
A first positive lens group disposed adjacent to the first surface side of the aperture stop and having one or more positive lenses and not including a negative lens;
A first negative lens group disposed adjacent to the first surface side of the first positive lens group and having one or more negative lenses and not including a positive lens;
A second positive lens group disposed adjacent to the first surface side of the first negative lens group and having one or more positive lenses and not including a negative lens;
A third positive lens group disposed adjacent to the second surface side of the aperture stop and having one or more positive lenses and not including a negative lens;
A second negative lens group disposed adjacent to the second surface side of the third positive lens group and having one or more negative lenses and not including a positive lens;
A fourth positive lens group disposed adjacent to the second surface side of the second negative lens group and having one or more positive lenses and not including a negative lens;
A gas lens disposed in an optical path between the first positive lens group and the third positive lens group;
When the on-axis thickness of the gas lens is D1, and the total length of the projection optical system is L, the following condition is satisfied.
0.02 <(D1 / L) <0.2 In a projection optical system that forms an image of a first surface on a second surface,
A first lens group disposed in an optical path between the first surface and the second surface and including at least two negative lenses and having a negative refractive power;
A second lens group disposed in an optical path between the first lens group and the second surface, the second lens group including at least three positive lenses and having a positive refractive power;
A third lens group disposed in an optical path between the second lens group and the second surface and including at least two biconcave lenses and having a negative refractive power;
A fourth lens group disposed in an optical path between the third lens group and the second surface and including an aperture stop and having a positive refractive power;
The fourth lens group includes:
A first positive lens group disposed adjacent to the first surface side of the aperture stop and having one or more positive lenses and not including a negative lens;
A first negative lens group disposed adjacent to the first surface side of the first positive lens group and having one or more negative lenses and not including a positive lens;
A second positive lens group disposed adjacent to the first surface side of the first negative lens group and having one or more positive lenses and not including a negative lens;
A third positive lens group disposed adjacent to the second surface side of the aperture stop and having one or more positive lenses and not including a negative lens;
A second negative lens group disposed adjacent to the second surface side of the third positive lens group and having one or more negative lenses and not including a positive lens;
A fourth positive lens group disposed adjacent to the second surface side of the second negative lens group and having one or more positive lenses and not including a negative lens;
A first gas lens disposed in an optical path between the first positive lens group and the first negative lens group and having a positive refractive power;
A second gas lens disposed in an optical path between the third positive lens group and the second negative lens group and having a positive refractive power;
A projection optical system comprising: The fourth lens group includes a gas lens disposed between the first positive lens group and the third positive lens group,
4. The projection optical system according to claim 1, wherein the following condition is satisfied when an on-axis thickness of the gas lens is D <b> 1 and an overall length of the projection optical system is L. 5.
0.02 <(D1 / L) <0.2 The fourth lens group includes:
A first gas lens disposed in an optical path between the first positive lens group and the first negative lens group and having a positive refractive power;
A second gas lens disposed in an optical path between the third positive lens group and the second negative lens group and having a positive refractive power;
The projection optical system according to claim 1, further comprising: The projection optical system according to claim 1, wherein at least one positive lens in the fourth lens group is made of fluorite. The fourth lens group includes:
A third negative lens group disposed in an optical path between the second positive lens group and the third lens group and having one or more negative lenses and not including a positive lens;
A fourth negative lens group disposed in an optical path between the fourth positive lens group and the second surface, the fourth negative lens group including one or more negative lenses and not including a positive lens;
With
The lens surface on the aperture stop side of at least one lens forming the third negative lens group has a concave surface facing the second surface side, and the aperture stop side of at least one lens forming the fourth negative lens group. The projection optical system according to any one of claims 1 to 6, wherein the surface (1) has a concave surface facing the first surface side. 8. The projection optical system according to claim 1, wherein at least one of the first lens group and the third lens group has an aspheric lens surface. 9. . A projection optical system according to any one of claims 1 to 8,
An illumination optical system that illuminates the reticle disposed on the first surface,
An exposure apparatus, wherein an image of the reticle pattern is projected onto a substrate disposed on the second surface via the projection optical system by exposure light from the illumination optical system. An illumination step of illuminating a reticle arranged on the first surface using the illumination optical system according to any one of claims 1 to 8.
An exposure step of transferring the pattern of the reticle onto a substrate disposed on the second surface.

Images