JP3852196B2

JP3852196B2 - Projection optical system, projection exposure apparatus, and scanning projection exposure method

Info

Publication number: JP3852196B2
Application number: JP36274197A
Authority: JP
Inventors: 泰弘大村
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 1997-12-12
Filing date: 1997-12-12
Publication date: 2006-11-29
Anticipated expiration: 2017-12-12
Also published as: JPH11176741A

Description

【０００１】
【発明の属する技術分野】
本発明は、投影光学系、投影露光装置及び走査投影露光方法に関し、特に短波長域で使用される、反射屈折光学系を含む投影光学系、投影露光装置及び走査投影露光方法に関するものである。
【０００２】
【従来の技術】
従来開示されている反射屈折光学系のうち比較的大きな開口数を実現し、実用的な大きさの光学系の従来技術としては特公平７−１１１５１２号公報とＵＳＰ−４，７７９，９６６が挙げられる。これらに開示された反射屈折光学系は、光軸を含まないスリット状もしくは円弧状の視野を用い、物体面と結像面を同時に走査して大きな露光領域を得る、所謂ステップ・アンド・スキャン方式を採用し、中間像を作ってその付近に光路偏向部材を配置することで、ビームスプリッターを用いることなく光路分割を実現している。
【０００３】
【発明が解決しようとする課題】
しかしながら、このような光学系では光路偏向部材として反射膜のコーティングされた１つまたは複数の平面反射鏡を用いる。このような場合、平面反射鏡はＰ偏光とＳ偏光で反射率が違い、特に露光波長が短くなると膜材料の減少等で反射膜によるＰ偏光とＳ偏光で反射率の違いをなくすことができなくなり、方向性をもった偏光光が生じてしまう。投影露光に方向性をもった偏光光を用いるとレチクルパターンの方向性により結像性能が変化してしまう。特に結像側で大きな開口数をもつ場合、この結像性能の変化が顕著で大きな問題となる。
【０００４】
本発明は斯かる点に鑑み、紫外線波長域で大きな開口数を達成し、光学系が実用的な大きさで、レチクルパターンの方向性に依存しない、クオーターミクロン単位の解像度を有する反射屈折光学系及び該光学系を備える投影露光装置を提供することを目的とする。
【０００５】
【課題を解決するための手段】
上記目的を達成するために、請求項１に係る発明による投影光学系は、図１に示すように、第１面１０１と第２面１２２を相対的に走査して、第１面１０１の像を第２面１２２に結像する走査型投影露光装置に用いられる投影光学系１０において；第１面１０１の中間像ＩＭを形成する第１結像光学系１００と；中間像ＩＭの像を第２面１２２上に形成する第２結像光学系１２０と；中間像ＩＭの近傍に配置され、第１結像光学系１００からの光を第２結像光学系１２０へ導く光路偏向部材１１１と；光路偏向部材１１１と第２面１２２との間の光路中に配置され、偏光面を変化させる第１偏光手段１２１とを備え；第１結像光学系１００は、屈折光学系Ｇ１、Ｇ２と凹面鏡１０２とを含み；第１結像光学系１００は、前記結像に該第１結像光学系１００の光軸からはずれた露光領域の光を用いるように構成されている。
【０００６】
光軸からはずれた露光領域とは、光軸を含まない例えばスリット状や円弧状の露光領域である。また第１面１０１と第２面１２２との相対的な走査は同期して行われる。
【０００７】
このように構成すると、中間像ＩＭの近傍に配置された光路偏向部材１１１を備えるので、第１結像光学系１００からの光が第２結像光学系１２０へ導かれ、光路偏向部材１１１と第２面１２２との間の光路中に偏光面を変化させる第１偏光手段１２１とを備えるので、第１偏光手段１２１までの光路でその光が非円偏光になっていたとしても、それを円偏光にすることができる。また、第１結像光学系１００は凹面鏡１０２を含むので、収差を抑えることができ、第１結像光学系１００は、前記結像に該第１結像光学系１００の光軸からはずれた露光領域の光を用いるように構成されているので、光路偏向部材１１１は第１結像光学系１００の光軸からはずれた位置に置くことができ、透過反射面を用いない構成が可能である。
【０００８】
この投影光学系では、請求項２に記載のように、前記第１面１０１を円偏光で照明する円偏光供給手段を備え；第１偏光手段１２１は２分の１波長板としてもよい。
【０００９】
請求項１に記載の投影光学系では、請求項３に記載のように、第１面１０１を直線偏光で照明する直線偏光供給手段を備え；前記第１偏光手段は４分の１波長板としてもよい。
【００１０】
このように構成すると、光路偏向部材１１１等で生じる方向性を予めコントロールすることができる。
【００１１】
請求項４に記載のように、以上に記載の投影光学系では、凹面鏡１０２と光路偏向部材１１１との間の光路中に、光路偏向部材１１１に入射する光を直線偏光にする第２偏光手段１３１を備えてもよい。
【００１２】
このように構成すると、第２偏光手段１３１が光を光路偏向部材１１１に入射する前に直線偏光にする。このことにより、偏向面における光量損失を少なくできる。
【００１３】
また、前記目的を達成するために、請求項５に係る発明による投影光学系は、図２に示すように、第１面１０１と第２面１２２とを相対的に走査して、第１面１０１の像を第２面１２２に結像する走査型投影露光装置に用いられる投影光学系１０において、屈折光学系Ｇ１、Ｇ２と凹面鏡１０２とを含み、第１面１０１の中間像ＩＭを形成する第１結像光学系１００と；中間像ＩＭの像を第２面１２２上に形成する第２結像光学系１２０と；中間像ＩＭの近傍に配置され、第１結像光学系１００からの光を第２結像光学系１２０へ導く光路偏向部材１１１とを備え；第１結像光学系１１０は、前記結像に第１結像光学系１００の光軸からはずれた露光領域の光を用いるように構成され；光路偏向部材１１１に対してＳ偏光の直線偏光を光路偏向部材１１１に入射させるように構成されている。
【００１４】
請求項６に記載のように、請求項５に記載の投影光学系では、光路偏向部材１１１の入射側に配置された偏光板または波長板１３１をさらに備えてもよい。
【００１５】
以上の投影光学系では、請求項７に記載のように、第２結像光学系１２０が屈折光学系から成るようにしてもよい。
【００１６】
以上の投影光学系は、請求項８に記載のように、前記屈折光学系は、石英と蛍石を含む硝材で作られたレンズを有してもよい。
【００１７】
このように構成すると、硝材が石英を含むレンズと蛍石を含むレンズを有するので、短波長例えば３００ｎｍ以下の光に対しても使用することができ、しかも凹面鏡を備えるので、アッベ数がお互いに近い石英と蛍石であっても、色収差の補正が容易である。
【００１８】
以上の投影光学系は、請求項９に記載のように、第１結像光学系１００は、第１面１０１に続いて配置されるように構成されてもよい。
【００１９】
請求項１０に記載の投影露光装置は、例えば図３に示すように、請求項１乃至請求項９のいずれかに記載の投影光学系１０と；第１面１０１を有するレチクルＲを保持するレチクルステージ１５１と；第２面１２２を有する基板Ｗを保持する基板ステージ１５２とを備える。
【００２０】
請求項１１に記載の走査投影露光方法は、請求項１乃至請求項９のいずれかに記載の投影光学系を用いて第１面１０１を有するレチクルＲの像を第２面１２２を有する基板Ｗ上に投影露光する工程と；レチクルＲと基板Ｗとを相対的に走査する工程とを備える。
【００２１】
【発明の実施の形態】
以下、本発明の実施の形態について、図面を参照して説明する。なお、各図において互いに同一あるいは相当する部材には同一符号を付し、重複した説明は省略する。
【００２２】
図１は、本発明による第１の実施の形態である走査型投影光学系１０の概略構成図である。図中、第１面であるパターンの形成された面１０１を下側に向けてレチクルステージ１５１（図３参照）上に保持されたレチクルＲの下方に、第１結像光学系１００が配置されている。
【００２３】
第１結像光学系１００は、レチクルＲ側から、屈折光学系である正の屈折力を有する第１レンズ群Ｇ１、屈折光学系である負の屈折力を有する第２レンズ群Ｇ２、そして凹面鏡１０２がこの順に配列されている。
【００２４】
さらに第１レンズ群Ｇ１と第２レンズ群Ｇ２との間の、第１結像光学系１００によって中間像ＩＭが結像される位置とほぼ一致する位置で、かつ両レンズ群の光軸からはずれた位置に、光路偏向部材である反射鏡１１１が配置されている。反射鏡１１１は、その反射面が第１レンズ群Ｇ１と第２レンズ群Ｇ２の光軸に対してほぼ４５度をなすように置かれている。
【００２５】
さらに、反射鏡１１１により偏向された光路に沿って第２結像光学系１２０が配置されている。
【００２６】
第２結像光学系１２０は、反射鏡１１１の側から、屈折光学系である正の屈折力を有する第３レンズ群Ｇ３、やはり屈折光学系である正の屈折力を有する第４レンズ群Ｇ４がこの順に配列されて構成されており、第２結像光学系１２０に関して中間像ＩＭと共役な位置に、第２面である基板の被露光面１２２を第４レンズ群Ｇ４の方に向けて、基板であるウエハＷが置かれるようになっている。ウエハＷはウエハステージ１５２（図３参照）上に保持されるように構成されている。
【００２７】
第３レンズ群Ｇ３と第４レンズ群Ｇ４との間の瞳の位置には、開口絞りＡＳが配置され、第３レンズ群Ｇ３と開口絞りＡＳとの間には、偏光面を変化させる第１偏光手段である波長板１２１が、第３レンズ群Ｇ３と第４レンズ群Ｇ４の光軸に直角に置かれている。なお、第１偏光手段である波長板１２１を置く位置は、第３レンズ群Ｇ３と開口絞りＡＳとの間に限らず、光路偏向部材である反射鏡１１１と第２面１２２との間ならどこでもよい。
【００２８】
波長板１２１は、４分の１波長（λ／４）板や２分の１波長（λ／２）板である。この波長板１２１により、ウエハＷの被露光面１２２に入射する光を円偏光にする。４分の１波長板と２分の１波長板は、次のように使い分ける。
【００２９】
第１面であるレチクル面１０１で直線偏光であるときは、偏向鏡１１１の後の状態はやはり直線偏光であり、第１偏光手段１２１を４分の１波長板とすれば、直線偏光が円偏光に変化され、第２面であるウエハ面１２２に入射する光は円偏光となる。
【００３０】
次に、第１面であるレチクル面１０１で円偏光であるときは、偏向鏡１１１の後の状態は一般には楕円偏光となり、第１偏光手段１２１を２分の１波長板とすれば、楕円偏光が円偏光に変化され、第２面であるウエハ面１２２に入射する光は円偏光となる。
【００３１】
本実施の形態では、第１レンズ群Ｇ１、第２レンズ群Ｇ２、第３レンズ群Ｇ３、第４レンズ群Ｇ４は、硝材として合成石英あるいは蛍石、または合成石英と蛍石とを併せて用いている。合成石英と蛍石を用いた場合の作用については後述する。
【００３２】
レチクルステージ１５１とウエハステージ１５２とは、相対的に同期して走査される。即ち図３において、投影光学系１０の光軸方向をＺ、Ｚ軸に直交する平面内の直交座標系であるＸＹ座標を、図中紙面に直角な方向にＸ軸、紙面内右方向にＹ軸をとると、レチクルステージ１５１がＹの正の方向に移動するとき、ウエハステージ１５２はＹの負方向に移動する。
【００３３】
レチクルステージ１５１の移動は、レチクルステージ駆動装置１５３により行われ、レチクルステージ１５１の位置はレチクルステージ干渉計１５４により検出される。
【００３４】
ウエハステージ１５２の移動は、ウエハステージ駆動装置１５５により行われ、ウエハステージ１５２の位置はウエハステージ干渉計１５６により検出される。
【００３５】
レチクルステージ干渉計１５４とウエハステージ干渉計１５６の出力は、制御装置１５７に入力され、制御装置１５７から出力される制御信号が、レチクルステージ駆動装置１５３とウエハステージ駆動装置１５５に入力され、所定の同期速度でお互いに相対的に走査される。
【００３６】
レチクルステージ１５１の上方には、照明光学系１５８が設けられている。
【００３７】
このように構成された走査型投影光学系の作用を説明する。照明光学系１５８により均一に照明されたレチクルＲの面１０１上のパターンからの光は、第１レンズ群Ｇ１と第２レンズ群Ｇ２を透過して凹面鏡１０２に到る。凹面鏡１０２で反射された光は、第２レンズ群Ｇ２を再度透過した後、反射鏡１１１の置かれた位置付近に中間像ＩＭを結像する。
【００３８】
このようにして反射鏡１１１に入射した光は偏向され、第３レンズ群Ｇ３を透過し、波長板１２１で偏光面を変化され、開口絞りＡＳにより照明σ値が決定され、さらに第４レンズ群Ｇ４を介してウエハＷの面１２２に入射する。即ち、中間像ＩＭは面１２２に結像する。このとき、波長板１２１の作用により、面１２２に入射する光は円偏光にされる。したがって、レチクルＲのパターンの方向性によるウエハ面１２２上への結像性能の劣化を防ぐことができる。これが円偏光でないとすると、レチクルＲのパターンの縦横ラインの太さの均一性が崩れる。
【００３９】
また、屈折光学系の硝材として合成石英と蛍石が選択されて用いられているので、３００ｎｍ以下といった短い波長の照明光を使用しても光の吸収を抑えることができ、高い解像度の投影露光に適している。
【００４０】
石英と蛍石の硝材としての光の分散の違いを利用して、これらを用いた屈折光学系の色収差を補正するが、両者のアッベ数はあまり離れていないので、これらを用いたレンズだけでは色収差の補正が難しい。即ちあまりにも多くのレンズを必要とするため、光学系が大きくなりすぎる。
【００４１】
しかしながら、本実施の形態の投影光学系１０は反射光学系である凹面鏡１０２を含んでおり、反射光学系は色収差がなく、レンズとは逆のペッツバール和への寄与を示すため、反射光学系と屈折光学系とを組み合わせた反射屈折光学系である本実施の形態の光学系では、レンズ枚数の増加を招くことなく、色収差をはじめ諸収差を補正し、全体としてほぼ無収差にすることができる。このようにして、実用的な大きさで、集積度の高い半導体素子の製造に求められる極めて高い光学性能を達成することができる。
【００４２】
このように本発明の実施の形態によれば、紫外線波長等の短波長域で大きな開口数を達成し、光学系が実用的な大きさで、レチクルパターンの方向性に依存しない、クオーターミクロン単位の解像度を有する反射屈折光学系を備える走査型投影光学系及びそのような走査型投影光学系を備える投影露光装置を提供することができる。
【００４３】
また、反射鏡１１１は第１結像光学系１００の光軸からはずれた位置に置かれているので、レチクルＲのパターンの投影には、光軸を含まないスリット状もしくは円弧状の露光領域が用いられ、レチクルＲと結像面にあるウエハＷとを同期走査して大きな露光領域を得る走査型投影光学系で、偏光ビームスプリッタ等の透過反射面を用いずに光路分割を実現することができる。
【００４４】
すなわち、リング視野光学系は、光軸を含まないスリット状もしくは円弧状の視野を用い、物体面と結像面を同時に走査して大きな露光領域を得る、所謂ステップ・アンド・スキャン方式を採用し、中間像を作ってその付近に光路偏向部材を配置することで、ビームスプリッターを用いなくとも光路分割が実現できる。
【００４５】
また、大きな開口数を得る場合でも、光路偏向部材として反射膜のコーティングされた平面鏡を用いる必要がない。したがって、平面反射鏡におけるＰ偏光とＳ偏光で反射率が違い、特に露光波長が短くなると膜材料の減少等で反射膜によるＰ偏光とＳ偏光で反射率が違ってくるが、それらの違いによる、方向性をもった偏光光の心配もない。
【００４６】
投影露光に方向性をもった偏光光を用いるとレチクルパターンの方向性により結像性能が変化してしまい、特に結像側で大きな開口数をもつ場合に大きな問題となるが、この結像性能の変化も防止できる。
【００４７】
また、第１結像光学系１００に入射する光を直線偏光等の偏光光にすれば、光路偏向部材１１１等で生まれる方向性を予めコントロールし、光路偏向部材１１１と第２面１２２の間の光路中に、前記のように第１偏光手段１２１であるλ／４波長板等を配置することで容易に方向性の全くない円偏光で第２面１２２上に像を結像させることができる。
【００４８】
第１結像光学系１００に入射する光を直線偏光等の偏光光にするには、照明光学系１５８の光源（不図示）としてレーザーを用いる他、偏光子を通した光を用いる方法がある。
【００４９】
図１では、第１偏光手段１２１は第３レンズ群Ｇ３と開口絞りＡＳとの間に置かれているが、光路偏向部材１１１と第２面１２２との間であればよく、例えば開口絞りＡＳと第４レンズ群Ｇ４との間、あるいは光路偏向部材１１１と第３レンズ群Ｇ３との間、さらには第４レンズ群と第２面１２２との間であっても同様な効果が得られる。但し、第３レンズ群Ｇ３と第４レンズ群Ｇ４との間が好ましい。
【００５０】
図２を参照して、本発明による第２の実施の形態である走査型投影光学系１１を説明する。図２はその概略構成図である。図中、偏光面を変化させる第２偏光手段１３１が第２レンズ群Ｇ２と光路偏向部材１１１との間に設けられている。その他の構成は図１の実施の形態と同様である。
【００５１】
第２偏光手段１３１の作用を説明する。光路偏向部材１１１の反射面の光量損失を考えると、光は反射面に対してＳ偏光で入射することが望ましい。第２偏光手段１３１は偏光子であればよいが、典型的には偏光板が用いられ、光路偏向部材１１１に入射する光をＳ偏光の直線偏光に変化させる。あるいは４分の１波長板または２分の１波長板を用いてもよい。このようにして、光路偏向部材１１１での光量損失を最小限に抑える。
【００５２】
なお、本実施の形態では、第２偏光手段１３１は、図２に示されるように光路偏向部材１１１の直前に設けられた偏光板であるが、これに限らず、第１面１０１と光路偏向部材１１１の間の光路中に設けて、要は光路偏向部材１１１に入射する光をほぼＳ偏光の直線偏光にするように構成すればよい。また光量損失を抑えるということは、反射面に貼り付けられる反射膜の損傷を防止することにもつながる。
【００５３】
以上のように、本発明の実施の形態では、光学系の結像性能を考えると、第１結像光学系１００が結像光学系であるレンズ群Ｇ１、Ｇ２と反射光学系である１枚の凹面鏡１０２より構成され、光路偏向部材１１１は平面反射鏡で、第２結像光学系１２０が（パワーを有する光学系として）レンズ群Ｇ３、Ｇ４のみにより構成されることが好ましく、近時の半導体製造装置にならい、第１面１０１の１／４〜１／６倍程度の縮小像を第２面１２２の上に結像させることが好ましい。また、屈折光学系であるレンズの硝材としては、合成石英、蛍石を用いるのが好ましい。
【００５４】
なお、実際の走査型投影光学系としては、特開平８−３３４６９５に開示された光学系等がある。
【００５５】
次に、第３の実施の形態である投影露光装置は、図３に示されるように走査型投影光学系１０と、第１面１０１を有するレチクルＲを保持するレチクルステージ１５１と、第２面１２２を有する基板Ｗを保持する基板ステージ１５２とを備える。図３は、投影光学系１０が用いられる場合を示しているが、投影光学系１１に置き換えてもよい。
【００５６】
図３に示される投影露光装置では、ウエハＷの面１２２とレチクルＲの面１０１とは平行に配置されているが、このような配置は、図１あるいは図２の投影光学系において、第２結像光学系１２０のいずれかの位置に偏向ミラーを設置して、光軸を直角に下方に折り曲げることにより実現できる。
【００５７】
図３に示されるような走査型投影露光装置を用いることによって、第１と第２の実施の形態について説明したように、レチクルＲ上の微細なパターンをウエハのような基板Ｗ上に転写し、あるいは大きいプレートのような基板Ｗ上に転写して集積度の高い素子を製造することができる。
【００５８】
以上のように、例えば半導体素子、または液晶表示素子等をフォトリソグラフィ工程で製造する際に使用される投影露光装置の光学系に関し、特に光学系の要素として反射系を用いることにより、紫外線波長域でクオーターミクロン単位の解像度を有する反射屈折光学系とそのような光学系を備える投影露光装置を実現することができる。
【００５９】
【発明の効果】
以上のように本発明によれば、屈折光学系と凹面鏡とを含み、結像に第１結像光学系の光軸からはずれた露光領域の光を用い、第１偏光手段を用いるように構成しているので、レチクルパターンの方向性に依存せず、高い解像度を有し、しかも実用的な大きさの走査型投影光学系及びそのような投影光学系を備える投影露光装置が得られる。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態である走査型投影光学系の概略構成図である。
【図２】本発明の第２の実施の形態である走査型投影光学系の概略構成図である。
【図３】本発明の第３の実施の形態である投影露光装置の概略構成図である。
【符号の説明】
１０、１１走査型投影光学系
１００第１結像光学系
１０１第１面
１０２凹面鏡
１１１光路偏向部材
１２０第２結像光学系
１２１第１偏光手段
１２２第２面
１３１第２偏光手段
１５１レチクルステージ
１５２ウエハステージ
１５３レチクルステージ駆動手段
１５４レチクルステージ干渉計
１５５ウエハステージ駆動手段
１５６ウエハステージ干渉計
１５７制御装置
１５８照明光学系[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projection optical system, a projection exposure apparatus, and a scanning projection exposure method , and more particularly to a projection optical system including a catadioptric optical system, a projection exposure apparatus, and a scanning projection exposure method used in a short wavelength region.
[0002]
[Prior art]
Japanese Patent Publication No. 7-1111512 and USP-4,779,966 are examples of conventional technologies of a practically sized optical system that realize a relatively large numerical aperture among the conventionally disclosed catadioptric optical systems. It is done. The catadioptric optical systems disclosed in these are so-called step-and-scan systems that use a slit-shaped or arc-shaped field of view that does not include an optical axis, and simultaneously scan the object surface and the imaging surface to obtain a large exposure area. Is used, and an intermediate image is formed and an optical path deflecting member is disposed in the vicinity thereof, thereby realizing optical path division without using a beam splitter.
[0003]
[Problems to be solved by the invention]
However, in such an optical system, one or a plurality of plane reflecting mirrors coated with a reflecting film are used as the optical path deflecting member. In such a case, the reflectivity of the plane reflecting mirror is different between P-polarized light and S-polarized light. In particular, when the exposure wavelength is shortened, the difference in reflectance between P-polarized light and S-polarized light due to the reflecting film can be eliminated due to a decrease in film material. This results in the generation of polarized light with directionality. When polarized light having directionality is used for projection exposure, the imaging performance changes depending on the directionality of the reticle pattern. In particular, when the image forming side has a large numerical aperture, this change in image forming performance becomes a significant problem.
[0004]
In view of the above, the present invention achieves a large numerical aperture in the ultraviolet wavelength region, and the catadioptric optical system having a resolution in quarter micron units, which has a practical size and does not depend on the directionality of the reticle pattern. It is another object of the present invention to provide a projection exposure apparatus including the optical system.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the projection optical system according to the first aspect of the present invention scans the first surface 101 and the second surface 122 relative to each other as shown in FIG. In the projection optical system 10 used in the scanning projection exposure apparatus that forms an image on the second surface 122; the first imaging optical system 100 that forms the intermediate image IM of the first surface 101; and the image of the intermediate image IM A second imaging optical system 120 formed on the second surface 122; an optical path deflecting member 111 disposed in the vicinity of the intermediate image IM and guiding light from the first imaging optical system 100 to the second imaging optical system 120; A first polarizing unit 121 disposed in the optical path between the optical path deflecting member 111 and the second surface 122 and changing the plane of polarization; the first imaging optical system 100 includes refractive optical systems G1 and G2; A first imaging optical system 100 for the first imaging. It is configured to use light in an exposure region deviated from the optical axis of the optical system 100.
[0006]
The exposure area deviated from the optical axis is, for example, a slit-shaped or arc-shaped exposure area that does not include the optical axis. The relative scanning of the first surface 101 and the second surface 122 is performed in synchronization.
[0007]
If comprised in this way, since the optical path deflection | deviation member 111 arrange | positioned in the vicinity of the intermediate image IM is provided, the light from the 1st imaging optical system 100 will be guide | induced to the 2nd imaging optical system 120, and the optical path deflection | deviation member 111 and Since the first polarization means 121 for changing the polarization plane in the optical path between the second surface 122 and the first polarization means 121, even if the light is non-circularly polarized in the optical path to the first polarization means 121 It can be circularly polarized. In addition, since the first imaging optical system 100 includes the concave mirror 102, aberration can be suppressed, and the first imaging optical system 100 is deviated from the optical axis of the first imaging optical system 100 during the imaging. Since it is configured to use light in the exposure region, the optical path deflecting member 111 can be placed at a position deviated from the optical axis of the first imaging optical system 100, and a configuration without using a transmission / reflection surface is possible. .
[0008]
The projection optical system includes a circularly polarized light supplying unit that illuminates the first surface 101 with circularly polarized light as described in claim 2; the first polarizing unit 121 may be a half-wave plate.
[0009]
The projection optical system according to claim 1 includes linearly polarized light supplying means for illuminating the first surface 101 with linearly polarized light as described in claim 3, wherein the first polarizing means is a quarter-wave plate. Also good.
[0010]
If comprised in this way, the directionality produced with the optical path deflection | deviation member 111 grade | etc., Can be controlled previously.
[0011]
According to a fourth aspect of the present invention, in the projection optical system described above , the second polarizing means that linearly polarizes light incident on the optical path deflecting member 111 in the optical path between the concave mirror 102 and the optical path deflecting member 111. 131 may be provided.
[0012]
With this configuration, the second polarizing means 131 converts the light into linearly polarized light before entering the optical path deflecting member 111. This can reduce the light amount loss on the deflection surface.
[0013]
In order to achieve the above object, the projection optical system according to the fifth aspect of the present invention scans the first surface 101 and the second surface 122 relative to each other as shown in FIG. A projection optical system 10 used in a scanning projection exposure apparatus that forms an image 101 on a second surface 122 includes refractive optical systems G1 and G2 and a concave mirror 102, and forms an intermediate image IM of the first surface 101. A first imaging optical system 100; a second imaging optical system 120 that forms an image of the intermediate image IM on the second surface 122; and disposed in the vicinity of the intermediate image IM, from the first imaging optical system 100 An optical path deflecting member 111 that guides the light to the second imaging optical system 120; the first imaging optical system 110 emits light in an exposure region deviated from the optical axis of the first imaging optical system 100 for the imaging. S-polarized linearly polarized light is applied to the optical path deflecting member 111. It is configured to be incident on the member 111.
[0014]
As described in claim 6, the projection optical system according to claim 5 may further include a polarizing plate or a wave plate 131 disposed on the incident side of the optical path deflecting member 111.
[0015]
In the above projection optical system , as described in claim 7 , the second imaging optical system 120 may be composed of a refractive optical system.
[0016]
Above the projection optical system, as set forth in claim 8, wherein the refractive optical system may have a lens made of glass material comprising quartz and fluorite.
[0017]
If comprised in this way, since the glass material has a lens containing quartz and a lens containing fluorite, it can be used even for light having a short wavelength, for example, 300 nm or less, and also has a concave mirror, so that the Abbe numbers are mutually different. Even near quartz and fluorite, correction of chromatic aberration is easy.
[0018]
The above projection optical system may be configured such that the first imaging optical system 100 is arranged following the first surface 101 as described in claim 9.
[0019]
A projection exposure apparatus according to a tenth aspect includes, for example, a projection optical system 10 according to any one of the first to ninth aspects; and a reticle that holds a reticle R having a first surface 101, as shown in FIG. A stage 151 ; and a substrate stage 152 for holding a substrate W having a second surface 122.
[0020]
A scanning projection exposure method according to an eleventh aspect of the invention is directed to a substrate W having a second surface 122 and an image of the reticle R having the first surface 101 using the projection optical system according to any one of the first to ninth aspects. A projection exposure process; and a process of relatively scanning the reticle R and the substrate W.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the mutually same or equivalent member, and the overlapping description is abbreviate | omitted.
[0022]
FIG. 1 is a schematic configuration diagram of a scanning projection optical system 10 according to the first embodiment of the present invention. In the drawing, a first imaging optical system 100 is arranged below a reticle R held on a reticle stage 151 (see FIG. 3) with a surface 101 having a pattern as a first surface facing downward. ing.
[0023]
The first imaging optical system 100 includes, from the reticle R side, a first lens group G1 having a positive refractive power that is a refractive optical system, a second lens group G2 having a negative refractive power that is a refractive optical system, and a concave mirror. 102 are arranged in this order.
[0024]
Furthermore, the position between the first lens group G1 and the second lens group G2 is substantially the same as the position at which the intermediate image IM is formed by the first imaging optical system 100, and deviates from the optical axes of both lens groups. The reflecting mirror 111, which is an optical path deflecting member, is disposed at the position. The reflecting mirror 111 is placed so that its reflecting surface forms approximately 45 degrees with respect to the optical axes of the first lens group G1 and the second lens group G2.
[0025]
Further, the second imaging optical system 120 is arranged along the optical path deflected by the reflecting mirror 111.
[0026]
The second imaging optical system 120 includes, from the reflecting mirror 111 side, a third lens group G3 having a positive refractive power that is a refractive optical system, and a fourth lens group G4 having a positive refractive power that is also a refractive optical system. Are arranged in this order, and the exposed surface 122 of the substrate as the second surface is directed toward the fourth lens group G4 at a position conjugate with the intermediate image IM with respect to the second imaging optical system 120. A wafer W as a substrate is placed. The wafer W is configured to be held on a wafer stage 152 (see FIG. 3).
[0027]
An aperture stop AS is disposed at the position of the pupil between the third lens group G3 and the fourth lens group G4, and a first polarization plane is changed between the third lens group G3 and the aperture stop AS. A wave plate 121 that is a polarizing means is placed at right angles to the optical axes of the third lens group G3 and the fourth lens group G4. The position where the wave plate 121 serving as the first polarizing means is placed is not limited to the position between the third lens group G3 and the aperture stop AS, but anywhere between the reflecting mirror 111 serving as the optical path deflecting member and the second surface 122. Good.
[0028]
The wave plate 121 is a quarter wavelength (λ / 4) plate or a half wavelength (λ / 2) plate. By this wave plate 121, the light incident on the exposed surface 122 of the wafer W is circularly polarized. The quarter-wave plate and the half-wave plate are properly used as follows.
[0029]
When a linearly polarized light in the reticle plane 101 is a first surface, a state after a deflecting mirror 111 is again linearly polarized light, if the first polarization means 121 and quarter-wave plate, linearly polarized light The light that is changed to circularly polarized light and enters the wafer surface 122, which is the second surface, becomes circularly polarized light.
[0030]
Then, when a circularly polarized light at the reticle plane 101 is a first surface, a state after a deflecting mirror 111 is generally becomes elliptically polarized, if the first polarization means 121 and a half-wave plate, The elliptically polarized light is changed to circularly polarized light, and the light incident on the wafer surface 122 as the second surface becomes circularly polarized light.
[0031]
In the present embodiment, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 use synthetic quartz or fluorite, or synthetic quartz and fluorite in combination as a glass material. ing. The effect of using synthetic quartz and fluorite will be described later.
[0032]
Reticle stage 151 and wafer stage 152 are scanned relatively synchronously. That is, in FIG. 3, the optical axis direction of the projection optical system 10 is Z, and the XY coordinates, which is an orthogonal coordinate system in a plane orthogonal to the Z axis, are set to the X axis in the direction perpendicular to the paper surface in the drawing and Taking the axis, when the reticle stage 151 moves in the positive Y direction, the wafer stage 152 moves in the negative Y direction.
[0033]
The movement of reticle stage 151 is performed by reticle stage driving device 153, and the position of reticle stage 151 is detected by reticle stage interferometer 154.
[0034]
The wafer stage 152 is moved by the wafer stage driving device 155, and the position of the wafer stage 152 is detected by the wafer stage interferometer 156.
[0035]
Outputs of reticle stage interferometer 154 and wafer stage interferometer 156 are input to control device 157, and control signals output from control device 157 are input to reticle stage driving device 153 and wafer stage driving device 155, and a predetermined value is input. They are scanned relative to each other at a synchronous rate.
[0036]
An illumination optical system 158 is provided above the reticle stage 151.
[0037]
The operation of the thus configured scanning projection optical system will be described. The light from the pattern on the surface 101 of the reticle R uniformly illuminated by the illumination optical system 158 passes through the first lens group G1 and the second lens group G2 and reaches the concave mirror 102. The light reflected by the concave mirror 102 passes through the second lens group G2 again, and then forms an intermediate image IM near the position where the reflecting mirror 111 is placed.
[0038]
Thus, the light incident on the reflecting mirror 111 is deflected, transmitted through the third lens group G3, the plane of polarization is changed by the wave plate 121, the illumination σ value is determined by the aperture stop AS, and the fourth lens group. The light enters the surface 122 of the wafer W via G4. That is, the intermediate image IM is formed on the surface 122. At this time, the light incident on the surface 122 is circularly polarized by the action of the wave plate 121. Therefore, it is possible to prevent deterioration of the imaging performance on the wafer surface 122 due to the pattern direction of the reticle R. If this is not circularly polarized light, the uniformity of the thickness of the vertical and horizontal lines of the pattern of the reticle R is lost.
[0039]
In addition, since synthetic quartz and fluorite are selected and used as the glass material for the refractive optical system, light absorption can be suppressed even when illumination light with a short wavelength of 300 nm or less is used, and high-resolution projection exposure is possible. Suitable for
[0040]
Using the difference in the dispersion of light between quartz and fluorite glass materials, the chromatic aberration of the refractive optical system using these is corrected, but the Abbe number of both is not so far away, so only with lenses using these It is difficult to correct chromatic aberration. That is, since too many lenses are required, the optical system becomes too large.
[0041]
However, the projection optical system 10 of the present embodiment includes a concave mirror 102 which is a reflection optical system, and the reflection optical system has no chromatic aberration and exhibits a contribution to the Petzval sum opposite to the lens. In the optical system according to the present embodiment, which is a catadioptric optical system combined with a refractive optical system, various aberrations including chromatic aberration can be corrected without causing an increase in the number of lenses, and the entire system can be made substantially free of aberrations. . In this way, it is possible to achieve extremely high optical performance required for manufacturing a semiconductor element having a practical size and a high degree of integration.
[0042]
As described above, according to the embodiment of the present invention, a large numerical aperture is achieved in a short wavelength region such as an ultraviolet wavelength, and the optical system has a practical size and does not depend on the directionality of the reticle pattern. A scanning projection optical system including a catadioptric optical system having a resolution of 1 mm and a projection exposure apparatus including such a scanning projection optical system can be provided.
[0043]
Further, since the reflecting mirror 111 is placed at a position deviated from the optical axis of the first imaging optical system 100, the projection of the pattern of the reticle R has a slit-shaped or arc-shaped exposure area that does not include the optical axis. A scanning projection optical system used to obtain a large exposure area by synchronously scanning the reticle R and the wafer W on the imaging plane, and realizing optical path division without using a transmission / reflection surface such as a polarizing beam splitter. it can.
[0044]
In other words, the ring field optical system employs a so-called step-and-scan method that uses a slit-shaped or arc-shaped field that does not include an optical axis, and simultaneously scans the object surface and the imaging surface to obtain a large exposure area. By creating an intermediate image and arranging an optical path deflecting member in the vicinity thereof, optical path division can be realized without using a beam splitter.
[0045]
Even when obtaining a large numerical aperture, there is no need to use a coated plane mirror reflective film as an optical path deflecting direction member. Therefore, the reflectivity is different between the P-polarized light and the S-polarized light in the plane reflecting mirror. Particularly, when the exposure wavelength is shortened, the reflectivity is different between the P-polarized light and the S-polarized light due to the reduction of the film material. There is no worry about polarized light with directionality.
[0046]
If polarized light with directionality is used for projection exposure, the imaging performance changes due to the directionality of the reticle pattern, and this is a big problem especially when the imaging side has a large numerical aperture. Can also be prevented.
[0047]
Further, if the light incident on the first imaging optical system 100 is changed to polarized light such as linearly polarized light, the directionality generated by the optical path deflecting member 111 or the like is controlled in advance, and the distance between the optical path deflecting member 111 and the second surface 122 is controlled. By arranging the λ / 4 wavelength plate as the first polarizing means 121 as described above in the optical path, an image can be easily formed on the second surface 122 with circularly polarized light having no directivity. .
[0048]
To the light incident on the first imaging optical system 100 to the polarized light such as linearly polarized light, except for using a laser as a light source of the illumination optical system 158 (not shown), a method using a light through the polarizing child is there.
[0049]
In FIG. 1, the first polarizing means 121 is placed between the third lens group G3 and the aperture stop AS, but may be between the optical path deflecting member 111 and the second surface 122, for example, the aperture stop AS. The same effect can be obtained even between the first lens group G4 and the fourth lens group G4, between the optical path deflecting member 111 and the third lens group G3, and between the fourth lens group and the second surface 122. However, it is preferably between the third lens group G3 and the fourth lens group G4.
[0050]
A scanning projection optical system 11 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic configuration diagram thereof. In the figure, a second polarizing means 131 for changing the polarization plane is provided between the second lens group G2 and the optical path deflecting member 111. Other configurations are the same as those of the embodiment of FIG.
[0051]
The operation of the second polarizing means 131 will be described. Considering the light amount loss on the reflection surface of the optical path deflecting member 111, it is desirable that the light is incident on the reflection surface as S-polarized light. The second polarizing means 131 may be a polarizer, but typically a polarizing plate is used to change the light incident on the optical path deflecting member 111 to S-polarized linearly polarized light. Alternatively, a quarter wave plate or a half wave plate may be used. In this way, the light loss at the optical path deflecting member 111 is minimized.
[0052]
In the present embodiment, the second polarizing means 131 is a polarizing plate provided immediately before the optical path deflecting member 111 as shown in FIG. 2, but is not limited thereto, and the first surface 101 and the optical path deflecting are not limited thereto. What is necessary is just to comprise so that it may provide in the optical path between the members 111, and the light which injects into the optical path deflection | deviation member 111 may be made into substantially S-polarized linearly polarized light. In addition, suppressing the light loss also leads to preventing damage to the reflective film attached to the reflective surface.
[0053]
As described above, in the embodiment of the present invention, considering the imaging performance of the optical system, the first imaging optical system 100 is a lens group G1, G2 that is an imaging optical system and one sheet that is a reflection optical system. It is preferable that the optical path deflecting member 111 is a plane reflecting mirror, and the second imaging optical system 120 is configured only by the lens groups G3 and G4 (as an optical system having power). In accordance with the semiconductor manufacturing apparatus, it is preferable to form a reduced image about 1/4 to 1/6 times the first surface 101 on the second surface 122. Further, it is preferable to use synthetic quartz or fluorite as the glass material of the lens which is a refractive optical system.
[0054]
As an actual scanning projection optical system, there is an optical system disclosed in JP-A-8-334695.
[0055]
Next, as shown in FIG. 3, the projection exposure apparatus according to the third embodiment includes a scanning projection optical system 10, a reticle stage 151 holding a reticle R having a first surface 101, and a second surface. And a substrate stage 152 that holds a substrate W having 122. FIG. 3 shows a case where the projection optical system 10 is used, but the projection optical system 11 may be substituted.
[0056]
In the projection exposure apparatus shown in FIG. 3, the surface 122 of the wafer W and the surface 101 of the reticle R are arranged in parallel. This arrangement is the second in the projection optical system of FIG. 1 or FIG. This can be realized by installing a deflecting mirror at any position of the imaging optical system 120 and bending the optical axis downward at a right angle.
[0057]
By using a scanning projection exposure apparatus as shown in FIG. 3, a fine pattern on the reticle R is transferred onto a substrate W such as a wafer as described in the first and second embodiments. Alternatively, a highly integrated device can be manufactured by transferring onto a substrate W such as a large plate.
[0058]
As described above, for example, an optical system of a projection exposure apparatus used when manufacturing a semiconductor element, a liquid crystal display element, or the like in a photolithography process, in particular, an ultraviolet wavelength region by using a reflection system as an element of the optical system. Thus, it is possible to realize a catadioptric optical system having a resolution of a quarter micron unit and a projection exposure apparatus including such an optical system.
[0059]
【The invention's effect】
As described above, the present invention includes the refractive optical system and the concave mirror, and uses the light in the exposure region deviated from the optical axis of the first imaging optical system for imaging, and uses the first polarizing means. Therefore, a scanning projection optical system having a high resolution and a practical size irrespective of the directionality of the reticle pattern and a projection exposure apparatus including such a projection optical system can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a scanning projection optical system according to a first embodiment of the present invention.
FIG. 2 is a schematic configuration diagram of a scanning projection optical system according to a second embodiment of the present invention.
FIG. 3 is a schematic block diagram of a projection exposure apparatus according to a third embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 11 Scanning projection optical system 100 1st image formation optical system 101 1st surface 102 Concave mirror 111 Optical path deflection member 120 2nd image formation optical system 121 1st polarization means 122 2nd surface 131 2nd polarization means 151 Reticle stage 152 Wafer stage 153 Reticle stage driving means 154 Reticle stage interferometer 155 Wafer stage driving means 156 Wafer stage interferometer 157 Controller 158 Illumination optical system

Claims

In a projection optical system used in a scanning projection exposure apparatus that relatively scans a first surface and a second surface and forms an image of the first surface on the second surface;
A first imaging optical system for forming an intermediate image of the first surface;
A second imaging optical system for forming an image of the intermediate image on the second surface;
Wherein arranged in the vicinity of the intermediate image, and an optical path deflecting member for guiding light from the first imaging optical system to the second imaging optical system;
A first polarizing means disposed in an optical path between the optical path deflecting member and the second surface and changing a polarization plane;
The first imaging optical system includes a refractive optical system and a concave mirror;
The first imaging optical system is configured to use light in an exposure region deviated from an optical axis of the first imaging optical system for the imaging;
Projection optics .

Circularly polarized light supplying means for illuminating the first surface with circularly polarized light;
The projection optical system according to claim 1, wherein the first polarizing unit is a half-wave plate.

Linearly polarized light supplying means for illuminating the first surface with linearly polarized light;
It said first polarizing means, characterized in that a quarter wave plate, and wherein the projection optical system according to claim 1.

The optical path between the optical path deflecting member and said concave mirror, characterized in that it comprises a second polarizing means for the light incident on the optical path deflecting member to linearly polarized light, either one of claims 1 to 3 The projection optical system according to one item .

In a projection optical system used in a scanning projection exposure apparatus that relatively scans a first surface and a second surface and forms an image of the first surface on the second surface,
  A first imaging optical system that includes a refractive optical system and a concave mirror and forms an intermediate image of the first surface;
  A second imaging optical system for forming an image of the intermediate image on the second surface;
  An optical path deflecting member that is disposed in the vicinity of the intermediate image and guides light from the first imaging optical system to the second imaging optical system;
  The first imaging optical system is configured to use light in an exposure region deviated from an optical axis of the first imaging optical system for the imaging;
  S-polarized linearly polarized light is incident on the optical path deflecting member with respect to the optical path deflecting member;
Projection optics.

6. The projection optical system according to claim 5, further comprising a polarizing plate or a wave plate disposed on the incident side of the optical path deflecting member.

The second imaging optical system is characterized in that it consists of refractive optical system, a projection optical system according to any one of claims 1 to 6.

The projection optical system according to any one of claims 1 to 7 , wherein the refractive optical system includes a lens made of a glass material including quartz and fluorite.

The projection optical system according to claim 1, wherein the first imaging optical system is disposed subsequent to the first surface.

A projection optical system according to any one of claims 1 to 9 ;
A reticle stage for holding a reticle having the first surface;
A substrate stage for holding the substrate having the second surface;
Projection exposure apparatus.

Projecting and exposing a reticle image having the first surface onto a substrate having the second surface using the projection optical system according to any one of claims 1 to 9;
A step of relatively scanning the reticle and the substrate;
Scanning projection exposure method.