JP2004071758A - Aligner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aligner in which high transmissivity can be attained by lowering the partial pressure of oxygen in a short period of time by a relatively simple structure. <P>SOLUTION: The aligner for transferring/exposing the pattern of an original plate on a substrate coated with a photosensitive agent using light having a wavelength of 200 nm or less comprises one or more housings for enclosing the optical path of exposing light at least partially, an exposing light transmitting member provided at a part of the housing where the exposing light enters/exits, a unit for supplying purge gas to the housing, a sensor for measuring the partial pressure of exposing light absorbing gas in the housing, a unit for reducing the pressure in the housing, and a sensor for measuring the pressure in the housing. Before the aligner is used, purge gas is supplied into the housing until the partial pressure of the exposing light absorbing gas in the housing lowers to a specified level thus replacing the gas in the housing. Subsequently, the pressure in the housing is reduced to a specified level. <P>COPYRIGHT: (C)2004,JPO

Description

【０００６】
従って、波長λを短くすれば波長に比例して解像可能な線幅Ｒは小さくなり、開口数ＮＡをあげれば反比例して、解像可能な線幅Ｒは小さくなる。
【０００７】
一方、リソグラフィー工程上許容可能な線幅誤差内に収まるデフォーカス許容量ＤＯＦは、比例定数ｋ_２を用いて、以下の式で表される。
【０００８】
【数２】

【０００９】
従って、波長を短くすれば比例してデフォーカス許容量ＤＯＦは小さくなり、開口数ＮＡをあげれば２乗に反比例してデフォーカス許容量ＤＯＦは小さくなる。
【００１０】
つまり、半導体素子を微細化するためには、露光波長を短くする方法と、露光装置の開口数を上げる方法があるが、デフォーカス許容量をなるべく大きくとるためには、露光波長を短くする方が好適である。そのため、近年では、露光光源の波長を短くした露光装置の開発が行われている。
【００１１】
現在、主流の露光装置の露光光源は、波長約２４８ｎｍのＫｒＦエキシマレーザーであるが、更に露光波長を短くするために、露光光源としてＡｒＦエキシマレーザー（波長約１９３ｎｍ）、更にはＦ_２レーザー（波長約１５７ｎｍ）を用いた露光装置の開発がなされている。
【００１２】
２００ｎｍ以下の露光波長となると、２００ｎｍ以上の露光波長のときにはなかった新たな技術的な課題が発生する。それは、酸素（Ｏ_２）や水蒸気（Ｈ_２Ｏ）が非常に大きな吸収率をもっており、露光光を吸収してしまうため、効率的に基板上に露光を行うためには、光路中のそれら吸光気体の濃度（分圧）を低くしなければならないということである。
【００１３】
例えば、酸素の吸収係数はＦ_２レーザーを光源とする１５７ｎｍの光に対して、１９０／ｃｍ／ａｔｍである。従って、２５％の酸素が含まれる空気中では、他の気体による吸収がないとしても、１ｍｍあたりの透過率はｅｘｐ（−１９０×０．１×０．２５）＝０．００８６となってしまう。つまり、空気中では、１ｍｍ進むだけ９９．１％の光が吸収されてしまうのである。即ち、酸素を露光光路中から取り除き酸素の分圧をさげなければ、光路の透過率が低下し、露光光が露光面に達するまでにほとんどの光が吸収されてしまう。露光面に到達する光が少なくなってしまうと、基板に塗布された感光剤が感光するまでにかかる露光時間が長くなってしまい、露光装置の生産性（スループット）が低下してしまう。
【００１４】
露光光路中から酸素等の吸光気体の分圧を下げる従来技術として、筐体内を比較的吸収係数の小さい窒素、もしくはヘリウムで置換するという方法と、筐体内を真空にするという方法がある。
【００１５】
筐体内を窒素で置換する方法の場合、窒素の吸収係数は０．０００１／ｃｍ／ａｔｍであるので、１００％の窒素に置換できれば、１ｍｍあたりの透過率はｅｘｐ（−０．０００１×０．１×１）＝０．９９９９９となり、ほぼ１００％の透過率となる。残留酸素と１ｍ当りの透過率の関係を表１に示す。
【００１６】
【表１】

【００１７】
表１を参照するに、窒素で空気を置換し、酸素の分圧を１×１０^−６ａｔｍ以下にすることによって、９７％以上の透過率が得られる。
【００１８】
一方、筐体内を真空にする場合、酸素の分圧を１×１０^−６ａｔｍとするためには、空気の酸素の比率は２５％であるので、筐体内の圧力を４×１０^−６気圧に減圧することによって、１ｍあたり９７％以上の透過率が得られる。
【００１９】
【発明が解決しようとする課題】
しかしながら、筐体内を窒素に置換する方法は、１×１０^−６気圧の酸素分圧を達成するのに非常に時間がかかる。筐体の密閉度、及び流す窒素の純度および量にもよるが、検討用のチャンバーで標準的な条件での検討によれば、筐体内を大気解放後、窒素に置換を始めると、酸素の分圧が５×１０^−６ａｔｍに達するのに１時間、１×１０−６ａｔｍに到達するのに２４時間の間、窒素を流しつづける必要があった。実際の光学系においては複雑な凹凸や、ガスの流れの悪いところがあるので、更に時間のかかる可能性がある。
【００２０】
一方、筐体内を真空にする方法は、１×１０^−６気圧の酸素分圧を到達するまでの時間は、密閉度が高い条件で、高性能な真空ポンプを使えば１時間未満と、筐体内を窒素に置換する方法に比べて短い。しかしながら、４×１０^−６気圧という高真空を達成するためには筐体内の密閉度を相当高める必要がある。レンズや駆動部が存在する筐体の密閉度を上げることは設計的に困難であり、また達成できたとしても非常に複雑な構造となる。また、筐体内を真空にすることによって、駆動部に使用されている油や、レンズの保持に使用されている接着剤からの脱ガスが発生し、それらが光路に拡散し、光学系の表面に付着し、光学部材が汚染される可能性があるという問題がある。
【００２１】
そこで、本発明は、比較的簡易な構造でありながら、短時間に酸素の分圧を下げて高透過率を達成することができる露光装置を提供することを例示的目的とする。また、好適には筐体内の圧力を大気圧程度とし、筐体内からの脱ガスによる光学部材の汚染の危険性を下げることができる露光装置を提供することを別の例示的目的とする。
【００２２】
【課題を解決するための手段】上記目的を達成するために、本発明の一側面としての露光装置は、波長２００ｎｍ以下の光を用いて、原版のパターンを感光剤の塗布された基板上に転写露光するための露光装置であって、露光光の光路の少なくとも一部を密閉するために設けられた一以上の筐体と、前記筐体に前記露光光が出入りする部分に設けたれた露光光透過性の部材と、前記筐体にパージガスを供給するガス供給装置と、前記筐体内の露光光吸光気体の分圧を計測する分圧センサと、前記筐体の圧力を減圧する減圧装置と、前記筐体内の圧力を計測する圧力センサとを有し、使用前に、前記筐体内の前記露光光吸光気体の分圧が所定分圧以下になるまで、当該筐体内にパージガスを供給して、当該筐体内のガスを置換し、その後所定の圧力になるまで当該筐体内の圧力を減圧することを特徴とする。
【００２３】
本発明の別の側面としての露光装置は、波長２００ｎｍ以下の光を用いて、原版のパターンを感光剤の塗布された基板上に転写露光するための露光装置であって、露光光の光路の少なくとも一部を密閉するために設けられた一以上の筐体と、前記筐体に前記露光光が出入りする部分に設けたれた露光光透過性の部材と、前記筐体にパージガスを供給するガス供給装置と、前記筐体内の露光光吸光気体の分圧を計測する分圧センサと、前記筐体の圧力を減圧する減圧装置と、前記筐体内の圧力を計測する圧力センサとを有し、使用前に、前記筐体内の前記露光光吸光気体の分圧が所定分圧以下になるまで、当該筐体内にパージガスを供給して、当該筐体内のガスを置換し、その後所定の圧力になるまで、当該筐体内の圧力を減圧し、その後再び前記パージガスを供給し、当該筐体内の圧力を大気圧以上とすることを特徴とする。
【００２４】
上述の露光装置において、前記パージガスは、窒素、もしくはヘリウムであることを特徴とする。前記分圧センサが計測する露光光吸光気体は、酸素であることを特徴とする。前記パージガスを置換後の吸光物質の分圧をｘ気圧以下、減圧後の前記筐体内の圧力をｙ気圧以下であるとした場合、　ｘ×ｙ＝１×１０^−６以下であることを特徴とする。
【００２５】
本発明の更に別の側面としての露光装置は、一の筐体を大気開放した後、吸光気体の分圧を下げるために当該筐体の圧力を下げる際に、隣り合う筐体の圧力を前記筐体内の圧力と大気圧の中間の圧力程度まで減圧することを特徴とする。
【００２６】
本発明の他の目的及び更なる特徴は、以下添付図面を参照して説明される好ま
しい実施例によって明らかにされるであろう。
【００２７】
【発明の実施の形態】以下、添付図面を参照して、本発明の例示的な露光装置について説明する。図１は、本発明の一側面としての露光装置１００の例示的一形態を示す概略ブロック図である。
【００２８】
露光装置１００は、光源としてＦ_２レーザー１１０を用いている。露光装置１００は、複数に分割された筐体１２０（筐体１２０は、筐体１２０ａ乃至１２０ｈを総括するものとする）からなり、それぞれの筐体１２０の境界は、１５７ｎｍの露光光を透過するフッ化カルシウム（ＣａＦ_２）、もしくはフッ化マグネシウム（ＭｇＦ_２）の平行平板によってしきられている。筐体１２０は、本実施形態では、便宜上分割しただけであり、分割方法、及び分割数については任意であり、図１に示す通りでなくても本発明の範囲内である。
【００２９】
Ｆ_２レーザー１１０から射出された１５７ｎｍの波長の光は筐体１２０ａ及び筐体１２０ｂの中にある引き回し光学系によって照明光学系に導光される。導光された光は、筐体１２０ｃ、筐体１２０ｄ及び筐体１２０ｅの中にある照明光学系によって、筐体１２０ｆ内にあるレチクル１３０面上で均一な光強度分布で，所望の角度分布の光となる。筐体１２０ｇの中には投影光学系があり、レチクル１３０上にかかれたパターンが筐体１２０ｈの中にあるウェハ１４０上に投影されている。
【００３０】
図２を参照して、各筐体１２０内で吸光気体の分圧を下げる方法について説明する。図２は、図１に示す筐体１２０の概略構成図である。図２を参照するに、中央部は、露光光路の一部を密閉する筐体１２０であって、他の筐体１２０とシールガラス１２１ａ及び１２１ｂで分離されている。露光光は筐体１２０内にシールガラス１２１ａより入射し、対面にあるシールガラス１２１ｂより射出する。筐体１２０を開放した後、筐体１２０内の吸光気体の分圧を下げ、露光を開始するまでの手順を説明する。
【００３１】
まず、バルブＡ及びＢを開け、バルブＣを閉じる。窒素供給装置１２２より窒素を供給し、筐体１２０内の置換を行う。酸素濃度計１２３の出力が５×１０−６気圧以下になったら、窒素供給装置１２２からの窒素の供給をとめる。
【００３２】
次いで、バルブＡ及びＢを閉め、真空ポンプ１２４で筐体１２０内を引き始める。バルブＣを開け、筐体１２０内の圧力計１２５が０．２気圧以下になるまで真空に引く。
【００３３】
筐体１２０内の圧力計１２５が０．２気圧以下になったらバルブＣを閉じ、真空ポンプ１２４をとめ、露光を開始する。
【００３４】
以上の手順により、筐体１２０内の酸素の分圧を１×１０^−６気圧以下にすることが可能である。なお、他の筐体１２０も同様の手順を踏んで、酸素の分圧が１×１０^−６気圧以下になっている。
【００３５】
本実施形態においては、筐体１２０内の簡易なパージ系で減圧するので、露光中に気圧が変動する可能性が考えられる。そのため、投影光学系など気圧によるフォーカス変化、倍率変化が問題となる場合は、筐体１２０内の気圧変化をモニターすることで、投影光学系の性能変化量を算出し投影光学系のレンズの一部を駆動したり、フォーカスの目標値を修正したりするなどして投影光学系の性能変化を補正してやればよい。
【００３６】
また、筐体１２０内を減圧後、筐体１２０内を大気圧程度とするように、再度窒素を入れることも可能である。図２を参照して、各筐体１２０内で吸光気体の分圧を下げ、露光を開始するまでの手順を説明する。
【００３７】
まず、バルブＡ及びＢを開け、バルブＣを閉じる。窒素供給装置１２２より窒素を供給し、筐体１２０内の置換を行う。酸素濃度計１２３の出力が５×１０−６気圧以下になったら、窒素供給装置１２２からの窒素の供給をとめる。
【００３８】
次いで、バルブＡ及びＢを閉め、真空ポンプ１２４で筐体１２０内を引き始める。バルブＣを開け、筐体１２０内の圧力計１２５が０．２気圧以下になるまで真空に引く。
【００３９】
筐体１２０内の圧力計１２５が０．２気圧以下になったらバルブＣを閉じ、真空ポンプ１２４をとめる。その後、バルブＡを開け、窒素供給装置１２２から窒素を供給し、筐体１２０内の気圧を大気圧程度、もしくは大気圧以上とする。
【００４０】
筐体１２０内の気圧が大気圧程度、もしくは大気圧以上となったらバルブＢを開け、露光を開始する。
【００４１】
以上の手順により、筐体１２０内の酸素の分圧を１×１０^−６気圧以下にすることが可能であり、かつ筐体１２０内の気圧を大気圧程度、もしくは大気圧以上にすることができ、駆動部の油や、接着剤からの脱ガスを防ぐことができる。なお、他の筐体１２０も同様の手順を踏んで、酸素の分圧が１×１０^−６気圧以下になっている。
【００４２】
更に、筐体１２０内を減圧する際に、隣り合う筐体１２０の圧力を、大気圧と減圧する筐体１２０の圧力の中間の圧力にし、筐体１２０内を減圧後、筐体１２０内を大気圧程度とする際に、隣り合う筐体１２０の圧力も大気圧程度にするよう再度窒素を入れることも可能である。
【００４３】
図３を参照して、中央の筐体１２０を何らかの理由で大気開放した後、筐体１２０内で吸光気体の分圧を下げ、露光を開始するまでの手順を説明する。図３は、図１に示す筐体１２０の概略構成図である。
【００４４】
まず、バルブＡ及びＢを開け、バルブＣを閉じる。窒素供給装置１２２より窒素を供給し、筐体１２０内の置換を行う。酸素濃度計１２３の出力が５×１０−６気圧以下になったら、窒素供給装置１２２からの窒素の供給をとめる。
【００４５】
次いで、バルブＡ、Ａ´及びＡ´´とバルブＢ、Ｂ´及びＢ´´を閉め、真空ポンプ１２４で筐体１２０内を引き始める。バルブＣ、Ｃ´及びＣ´´を開け、中央の筐体１２０内の圧力計１２５が０．２気圧以下になるまで、両側の筐体１２０内の図示しない圧力計が０．６気圧以下になるまで真空に引く。
【００４６】
中央の筐体１２０内の気圧が０．２気圧以下、側の筐体１２０内の気圧が０．６気圧以下になったら、バルブＣ、Ｃ´及びＣ´´を閉じ、真空ポンプ１２４をとめる。
【００４７】
その後、バルブＡ、Ａ´及びＡ´´を開け、窒素供給装置１２２から窒素を供給し、各筐体１２０内の気圧を大気圧程度とする。各筐体１２０内の気圧が大気圧程度となったらバルブＢ、Ｂ´及びＢ´´を開け、露光を開始する。
【００４８】
以上の手順により、筐体１２０内の酸素の分圧を１×１０^−６気圧以下にすることが可能であり、かつ筐体１２０内の気圧を大気圧程度にすることができ、駆動部の油や、接着剤からの脱ガスを防ぐことができる。
【００４９】
更に、バルブＣ、Ｃ´及びＣ´´を開け、中央の筐体１２０内の圧力計１２５が０．２気圧以下になるまで、両側の筐体１２０内の図示しない圧力計が０．６気圧以下になるまで真空に引く際に、上述した実施形態では０．８気圧の圧力がシールガラス１２１ａ及び１２１ｂにかかっていたのに対して、本実施形態では、０．４気圧の圧力となり、シールガラス１２１ａ及び１２１ｂの耐圧性を緩和することができる。
【００５０】
以上、本発明の好ましい実施例を説明したが、本発明はこれらに限定されずその要旨の範囲内で種々の変形及び変更が可能である。
【００５１】
【発明の効果】本発明の露光装置によれば、ガスを抜いたときの真空度が低いため、比較的簡易な筐体構造であり、かつ、窒素への置換により達成する酸素分圧のレベルも低いため比較的短時間に酸素の分圧を下げて、露光光路を光透過率にすることが可能である。
【図面の簡単な説明】
【図１】本発明の一側面としての露光装置の例示的一形態を示す概略ブロック図である。
【図２】図１に示す筐体の概略構成図である。
【図３】図１に示す筐体の概略構成図である。
【符号の説明】
１００　　　　　　　　　　　露光装置
１１０　　　　　　　　　　　Ｆ_２レーザー
１２０　　　　　　　　　　　筐体
１２１ａ及び１２１ｂ　　　　シールガラス
１２２　　　　　　　　　　　窒素供給装置
１２３　　　　　　　　　　　酸素濃度計
１２４　　　　　　　　　　　真空ポンプ
１２５　　　　　　　　　　　圧力計[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to an exposure apparatus that illuminates a mask on which a pattern is formed using light emitted from an exposure light source and transfers and exposes the pattern on a substrate coated with a photosensitive agent. The present invention relates to an exposure apparatus used in a lithography process for manufacturing a device, a liquid crystal display device, an imaging device (such as a CCD), a thin film magnetic head, and the like.
[0002]
[Prior art]
An exposure apparatus is used in a lithography process in a semiconductor device manufacturing process. The lithography step is a step of projecting and transferring a circuit pattern of a semiconductor element onto a substrate (such as a silicon substrate) to be a semiconductor element.
[0003]
In recent years, the demand for miniaturization of semiconductor devices has been increasing more and more, and the minimum line width of lines and spaces is less than 0.15 μm and is approaching 0.10 μm. In order to achieve miniaturization, improvement of the resolving power of a projection exposure apparatus used in a lithography process has been a major issue in recent years.
[0004]
Generally, resolvable linewidth R in the lithography step, the wavelength λ of the exposure light source, the numerical aperture NA of the exposure apparatus, using a proportionality constant k _1, is represented by the following equation.
[0005]
(Equation 1)

[0006]
Therefore, the shorter the wavelength λ, the smaller the resolvable line width R becomes proportional to the wavelength, and the higher the numerical aperture NA, the smaller the resolvable line width R becomes.
[0007]
On the other hand, the defocus tolerance DOF fit in lithography process acceptable line in width error using the proportional constant k _2, is represented by the following equation.
[0008]
(Equation 2)

[0009]
Therefore, if the wavelength is shortened, the permissible defocus amount DOF is reduced in proportion, and if the numerical aperture NA is increased, the permissible defocus amount DOF is reduced in inverse proportion to the square.
[0010]
In other words, there are a method of shortening the exposure wavelength and a method of increasing the numerical aperture of the exposure apparatus in order to miniaturize the semiconductor element. However, in order to increase the allowable defocus amount as much as possible, it is necessary to shorten the exposure wavelength. Is preferred. Therefore, in recent years, an exposure apparatus in which the wavelength of an exposure light source is shortened has been developed.
[0011]
Currently, an exposure light source of mainstream exposure apparatus is a KrF excimer laser with a wavelength of approximately 248 nm, in order to further shorten the exposure wavelength, ArF excimer laser (wavelength: about 193 nm) as the exposure light source, even _{F 2} laser (wavelength An exposure apparatus using about 157 nm has been developed.
[0012]
When the exposure wavelength is 200 nm or less, a new technical problem that does not occur when the exposure wavelength is 200 nm or more occurs. This is because oxygen (O ₂ ) and water vapor (H ₂ O) have a very high absorptivity and absorb the exposure light. This means that the gas concentration (partial pressure) must be reduced.
[0013]
For example, the absorption coefficient of oxygen to light of 157nm as a light source an _{F 2} laser, is 190 / cm / atm. Therefore, in air containing 25% oxygen, the transmittance per mm is exp (−190 × 0.1 × 0.25) = 0.0086 even if there is no absorption by other gases. . That is, in air, 99.1% of light is absorbed by 1 mm. That is, if oxygen is not removed from the exposure light path and the partial pressure of oxygen is not reduced, the transmittance of the light path decreases, and most of the light is absorbed before the exposure light reaches the exposure surface. If the amount of light that reaches the exposure surface decreases, the exposure time required until the photosensitive agent applied to the substrate is exposed increases, and the productivity (throughput) of the exposure apparatus decreases.
[0014]
As a conventional technique for lowering the partial pressure of a light-absorbing gas such as oxygen from the exposure light path, there are a method of replacing the inside of the housing with nitrogen or helium having a relatively small absorption coefficient, and a method of evacuating the inside of the housing.
[0015]
In the case of replacing the interior of the housing with nitrogen, the nitrogen absorption coefficient is 0.0001 / cm / atm. Therefore, if 100% of nitrogen can be replaced, the transmittance per mm is exp (−0.0001 × 0. 1 × 1) = 0.99999, which is almost 100% transmittance. Table 1 shows the relationship between the residual oxygen and the transmittance per meter.
[0016]
[Table 1]

[0017]
Referring to Table 1, by replacing air with nitrogen and setting the partial pressure of oxygen to 1 × 10 ⁻⁶ atm or less, a transmittance of 97% or more can be obtained.
[0018]
On the other hand, when the enclosure is evacuated, to the partial pressure of oxygen between 1 × 10 -6 ^atm, since the ratio of air oxygen is 25%, 4 × 10 ^-6 atm pressure in the enclosure By reducing the pressure, a transmittance of 97% or more per 1 m can be obtained.
[0019]
[Problems to be solved by the invention]
However, the method of replacing the inside of the housing with nitrogen takes a very long time to achieve an oxygen partial pressure of 1 × 10 ⁻⁶ atm. Depending on the degree of sealing of the enclosure and the purity and amount of nitrogen flowing, according to examinations under standard conditions in the examination chamber, after the interior of the enclosure is released to atmosphere and then replaced with nitrogen, oxygen It was necessary to keep flowing nitrogen for 1 hour to reach a partial pressure of 5 × 10 ⁻⁶ atm and 24 hours to reach 1 × 10 ⁻⁶ atm. In an actual optical system, there are complicated irregularities and a place where gas flow is poor, so that it may take more time.
[0020]
On the other hand, the method of evacuating the inside of the casing is as follows: the time until the partial pressure of oxygen of 1 × 10 ⁻⁶ atm is reached is less than one hour if a high-performance vacuum pump is used under high sealing conditions. It is shorter than the method of replacing the body with nitrogen. However, in order to achieve a high vacuum of 4 × 10 ⁻⁶ atm, it is necessary to considerably increase the degree of sealing in the housing. It is difficult in terms of design to increase the degree of sealing of the housing in which the lens and the drive unit are present, and even if achieved, the structure becomes very complicated. In addition, when the inside of the housing is evacuated, degassing occurs from the oil used in the driving unit and the adhesive used to hold the lens, and these are diffused into the optical path, and the surface of the optical system is diffused. And the optical member may be contaminated.
[0021]
Accordingly, an object of the present invention is to provide an exposure apparatus which has a relatively simple structure and can achieve a high transmittance by reducing the partial pressure of oxygen in a short time. It is another exemplary object to provide an exposure apparatus capable of reducing the risk of contamination of an optical member due to degassing from the inside of the housing, preferably by setting the pressure in the housing to about the atmospheric pressure.
[0022]
In order to achieve the above object, an exposure apparatus according to one aspect of the present invention uses a light having a wavelength of 200 nm or less to form a pattern of an original on a substrate coated with a photosensitive agent. An exposure apparatus for performing transfer exposure, comprising: at least one housing provided to seal at least a part of an optical path of exposure light; and an exposure device provided at a portion where the exposure light enters and exits the housing. A light-transmissive member, a gas supply device that supplies a purge gas to the housing, a partial pressure sensor that measures a partial pressure of the exposure light-absorbing gas in the housing, and a decompression device that reduces the pressure of the housing. Having a pressure sensor for measuring the pressure in the housing, before use, until the partial pressure of the exposure light-absorbing gas in the housing becomes equal to or less than a predetermined partial pressure, supplying a purge gas into the housing. , Replacing the gas in the housing, and then Characterized by reducing the pressure of the housing until the force.
[0023]
An exposure apparatus according to another aspect of the present invention is an exposure apparatus for transferring and exposing a pattern of an original onto a substrate coated with a photosensitive agent using light having a wavelength of 200 nm or less, and includes an optical path of exposure light. One or more housings provided for sealing at least a part thereof, an exposure light transmitting member provided at a portion where the exposure light enters and exits the housing, and a gas for supplying a purge gas to the housing. A supply device, a partial pressure sensor that measures the partial pressure of the exposure light-absorbing gas in the housing, a pressure reducing device that reduces the pressure in the housing, and a pressure sensor that measures the pressure in the housing, Before use, a purge gas is supplied into the housing to replace the gas in the housing until the partial pressure of the exposure light-absorbing gas in the housing becomes equal to or less than a predetermined partial pressure, and then the pressure becomes a predetermined pressure. Until the pressure inside the housing is reduced, and then again Supplying serial purge gas, characterized in that the pressure of the enclosure and above atmospheric pressure.
[0024]
In the above exposure apparatus, the purge gas is nitrogen or helium. The exposure light absorbing gas measured by the partial pressure sensor is oxygen. When the partial pressure of the light-absorbing substance after replacing the purge gas is x atmospheric pressure or less, and the pressure in the housing after the pressure reduction is y atmospheric pressure or less, x × y = 1 × 10 ⁻⁶ or less. I do.
[0025]
Exposure apparatus as still another aspect of the present invention, after opening one housing to the atmosphere, when lowering the pressure of the housing to reduce the partial pressure of the light-absorbing gas, the pressure of the adjacent housing is reduced The pressure is reduced to an intermediate pressure between the pressure in the housing and the atmospheric pressure.
[0026]
Other objects and further features of the present invention will be clarified by preferred embodiments described below with reference to the accompanying drawings.
[0027]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An exemplary exposure apparatus according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic block diagram illustrating an exemplary embodiment of an exposure apparatus 100 according to one aspect of the present invention.
[0028]
The exposure apparatus 100 uses the _{F 2} laser 110 as a light source. The exposure apparatus 100 includes a plurality of divided housings 120 (the housings 120 collectively include the housings 120a to 120h), and a boundary between the housings 120 transmits 157 nm exposure light. It is made up of parallel plates of calcium fluoride (CaF ₂ ) or magnesium fluoride (MgF ₂ ). In the present embodiment, the housing 120 is merely divided for the sake of convenience, and the dividing method and the number of divisions are arbitrary, and even if not shown in FIG. 1, they are within the scope of the present invention.
[0029]
Light of a wavelength of the injected 157nm from F ₂ laser 110 is guided to the illumination optical system by routing optical system that is in the housing 120a and a housing 120b. The guided light is uniformly distributed on the reticle 130 in the housing 120f by the illumination optical system in the housing 120c, the housing 120d, and the housing 120e. It becomes light. A projection optical system is provided in the housing 120g, and a pattern formed on the reticle 130 is projected on a wafer 140 in the housing 120h.
[0030]
With reference to FIG. 2, a method of reducing the partial pressure of the light-absorbing gas in each housing 120 will be described. FIG. 2 is a schematic configuration diagram of the housing 120 shown in FIG. Referring to FIG. 2, the central portion is a housing 120 that seals a part of the exposure light path, and is separated from other housings 120 by seal glasses 121a and 121b. Exposure light enters the housing 120 from the seal glass 121a and exits from the seal glass 121b on the opposite side. A procedure from opening the housing 120 to lowering the partial pressure of the light-absorbing gas in the housing 120 and starting exposure will be described.
[0031]
First, the valves A and B are opened, and the valve C is closed. Nitrogen is supplied from the nitrogen supply device 122 to replace the inside of the housing 120. When the output of the oxygen concentration meter 123 becomes 5 × 10 −6 atm or less, the supply of nitrogen from the nitrogen supply device 122 is stopped.
[0032]
Next, the valves A and B are closed, and the inside of the housing 120 is started to be pulled by the vacuum pump 124. The valve C is opened, and vacuum is drawn until the pressure gauge 125 in the housing 120 becomes 0.2 atm or less.
[0033]
When the pressure gauge 125 in the housing 120 becomes 0.2 atm or less, the valve C is closed, the vacuum pump 124 is stopped, and exposure is started.
[0034]
Through the above procedure, the partial pressure of oxygen in the housing 120 can be reduced to 1 × 10 ⁻⁶ atm or less. Note that the other housings 120 follow the same procedure and the partial pressure of oxygen is 1 × 10 ⁻⁶ atm or less.
[0035]
In this embodiment, since the pressure is reduced by the simple purge system in the housing 120, the pressure may fluctuate during the exposure. Therefore, when a change in focus or a change in magnification due to atmospheric pressure in the projection optical system poses a problem, the amount of change in performance of the projection optical system is calculated by monitoring the change in atmospheric pressure in the housing 120, and one of the lenses of the projection optical system is calculated. The performance change of the projection optical system may be corrected by driving the unit or correcting the focus target value.
[0036]
After the pressure in the housing 120 is reduced, nitrogen can be added again so that the pressure in the housing 120 is approximately the atmospheric pressure. With reference to FIG. 2, a procedure from lowering the partial pressure of the light-absorbing gas in each housing 120 to starting exposure will be described.
[0037]
First, the valves A and B are opened, and the valve C is closed. Nitrogen is supplied from the nitrogen supply device 122 to replace the inside of the housing 120. When the output of the oxygen concentration meter 123 becomes 5 × 10 −6 atm or less, the supply of nitrogen from the nitrogen supply device 122 is stopped.
[0038]
Next, the valves A and B are closed, and the inside of the housing 120 is started to be pulled by the vacuum pump 124. The valve C is opened, and vacuum is drawn until the pressure gauge 125 in the housing 120 becomes 0.2 atm or less.
[0039]
When the pressure gauge 125 in the housing 120 becomes 0.2 atm or less, the valve C is closed and the vacuum pump 124 is stopped. Thereafter, the valve A is opened, and nitrogen is supplied from the nitrogen supply device 122, and the pressure in the housing 120 is set to about atmospheric pressure or higher.
[0040]
When the air pressure in the housing 120 becomes equal to or higher than the atmospheric pressure, the valve B is opened to start exposure.
[0041]
Through the above procedure, the partial pressure of oxygen in the housing 120 can be reduced to 1 × 10 ⁻⁶ atm or less, and the atmospheric pressure in the housing 120 can be set to about atmospheric pressure or higher. Thus, it is possible to prevent degassing of the drive unit oil and the adhesive. Note that the other housings 120 follow the same procedure and the partial pressure of oxygen is 1 × 10 ⁻⁶ atm or less.
[0042]
Further, when depressurizing the inside of the housing 120, the pressure of the adjacent housing 120 is set to an intermediate pressure between the atmospheric pressure and the pressure of the housing 120 to be depressurized. When the pressure is set to about the atmospheric pressure, nitrogen can be added again so that the pressure of the adjacent housing 120 is also set to about the atmospheric pressure.
[0043]
With reference to FIG. 3, a description will be given of a procedure from opening the central housing 120 to the atmosphere for some reason, reducing the partial pressure of the light-absorbing gas in the housing 120, and starting exposure. FIG. 3 is a schematic configuration diagram of the housing 120 shown in FIG.
[0044]
First, the valves A and B are opened, and the valve C is closed. Nitrogen is supplied from the nitrogen supply device 122 to replace the inside of the housing 120. When the output of the oxygen concentration meter 123 becomes 5 × 10 −6 atm or less, the supply of nitrogen from the nitrogen supply device 122 is stopped.
[0045]
Next, the valves A, A ′ and A ″ and the valves B, B ′ and B ″ are closed, and the inside of the housing 120 is started by the vacuum pump 124. The valves C, C ′ and C ″ are opened, and the pressure gauges (not shown) in the housings 120 on both sides are reduced to 0.6 atmospheres or less until the pressure gauge 125 in the central housing 120 becomes 0.2 atmospheres or less. Apply vacuum until it is.
[0046]
When the air pressure in the central housing 120 becomes 0.2 atm or less and the air pressure in the side housing 120 becomes 0.6 atm or less, the valves C, C ′ and C ″ are closed and the vacuum pump 124 is stopped. .
[0047]
Thereafter, the valves A, A ′ and A ″ are opened, nitrogen is supplied from the nitrogen supply device 122, and the pressure in each housing 120 is reduced to about atmospheric pressure. When the pressure in each housing 120 becomes about atmospheric pressure, the valves B, B 'and B''are opened to start exposure.
[0048]
According to the above procedure, the partial pressure of oxygen in the housing 120 can be reduced to 1 × 10 ⁻⁶ atm or less, and the air pressure in the housing 120 can be reduced to about the atmospheric pressure. Degassing from oil and adhesive can be prevented.
[0049]
Further, the valves C, C ′ and C ″ are opened, and the pressure gauges (not shown) in the casings 120 on both sides are set to 0.6 atm until the pressure gauge 125 in the central casing 120 becomes 0.2 atm or less. When a vacuum is applied until the pressure becomes equal to or less than 0.8, the pressure of 0.8 atm is applied to the sealing glasses 121a and 121b in the above-described embodiment, whereas in the present embodiment, the pressure becomes 0.4 atm. The pressure resistance of the glasses 121a and 121b can be reduced.
[0050]
Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the gist.
[0051]
According to the exposure apparatus of the present invention, since the degree of vacuum at the time of degassing is low, it has a relatively simple housing structure, and the level of the oxygen partial pressure achieved by substitution with nitrogen. Therefore, it is possible to lower the partial pressure of oxygen in a relatively short time to make the exposure optical path have a light transmittance.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram illustrating an exemplary embodiment of an exposure apparatus according to one aspect of the present invention.
FIG. 2 is a schematic configuration diagram of a housing shown in FIG.
FIG. 3 is a schematic configuration diagram of a housing shown in FIG. 1;
[Explanation of symbols]
REFERENCE SIGNS LIST 100 Exposure device 110 F ₂ laser 120 Cases 121 a and 121 _b Seal glass 122 Nitrogen supply device 123 Oxygen concentration meter 124 Vacuum pump 125 Pressure gauge

Claims (6)

An exposure apparatus for transferring and exposing a pattern of an original onto a substrate coated with a photosensitive agent using light having a wavelength of 200 nm or less,
One or more housings provided to seal at least a part of the optical path of the exposure light,
An exposure light transmitting member provided at a portion where the exposure light enters and exits the housing,
A gas supply device for supplying a purge gas to the housing,
A partial pressure sensor that measures the partial pressure of the exposure light absorbing gas in the housing,
A pressure reducing device for reducing the pressure of the housing,
A pressure sensor for measuring the pressure in the housing,
Before use, a purge gas is supplied into the housing until the partial pressure of the exposure light-absorbing gas in the housing becomes equal to or less than a predetermined partial pressure, and the gas in the housing is replaced. An exposure apparatus, wherein the pressure in the housing is reduced until the exposure. An exposure apparatus for transferring and exposing a pattern of an original onto a substrate coated with a photosensitive agent using light having a wavelength of 200 nm or less,
One or more housings provided to seal at least a part of the optical path of the exposure light,
An exposure light transmitting member provided at a portion where the exposure light enters and exits the housing,
A gas supply device for supplying a purge gas to the housing,
A partial pressure sensor that measures the partial pressure of the exposure light absorbing gas in the housing,
A pressure reducing device for reducing the pressure of the housing,
A pressure sensor for measuring the pressure in the housing,
Before use, a purge gas is supplied into the housing until the partial pressure of the exposure light-absorbing gas in the housing becomes equal to or less than a predetermined partial pressure, and the gas in the housing is replaced. An exposure apparatus, wherein the pressure in the housing is reduced until the purge gas is supplied again to make the pressure in the housing equal to or higher than the atmospheric pressure. After releasing one housing to the atmosphere, when lowering the pressure of the housing to reduce the partial pressure of the light-absorbing gas, the pressure of the adjacent housing is reduced to a pressure intermediate between the pressure in the housing and the atmospheric pressure. An exposure apparatus for reducing pressure. 3. The exposure apparatus according to claim 1, wherein the purge gas is nitrogen or helium. 3. The exposure apparatus according to claim 1, wherein the exposure light absorbing gas measured by the partial pressure sensor is oxygen. When the partial pressure of the light-absorbing substance after replacing the purge gas is x atmospheric pressure or less, and the pressure in the housing after the pressure reduction is y atmospheric pressure or less,
x × y = 1 × 10 ⁻⁶
3. The exposure apparatus according to claim 1, wherein:

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