JPH11312631A - Illuminating optical device and aligner - Google Patents
Illuminating optical device and alignerInfo
- Publication number
- JPH11312631A JPH11312631A JP10117434A JP11743498A JPH11312631A JP H11312631 A JPH11312631 A JP H11312631A JP 10117434 A JP10117434 A JP 10117434A JP 11743498 A JP11743498 A JP 11743498A JP H11312631 A JPH11312631 A JP H11312631A
- Authority
- JP
- Japan
- Prior art keywords
- light beam
- optical
- light
- delay element
- light source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体素子を製造
する露光装置に関し、特に露光装置に用いられる照明光
学装置に関する。[0001] 1. Field of the Invention [0002] The present invention relates to an exposure apparatus for manufacturing a semiconductor device, and more particularly to an illumination optical apparatus used for the exposure apparatus.
【０００２】[0002]
【従来の技術】従来の照明光学装置は、例えば、特開平
１−１９８７５９号公報に開示されたものがある。一般
に、レーザー光源の半値幅をΔλ、波長をλとすると、
時間的可干渉長（コヒーレンス長）ｔｃは、 ｔｃ＝λ2 ／Δλ で与えられる。波長λ＝２４８ｎｍで半値幅Δλ＝０．
８ｐｍの場合は時間的コヒーレンス長ｔｃ＝７７ｍｍと
なり、波長λ＝２４８ｎｍで半値幅Δλ＝０．６ｐｍの
場合は時間的コヒーレンス長ｔｃ＝１０３ｍｍになる。
そこで、従来では、図１０に示されるように、光路中
に、ハーフミラー及び反射部材からなる光遅延素子を挿
入することで、コヒーレンス長以上の光路差を設け、可
干渉性（コヒーレンシー）の低減をはかっていた。光遅
延素子は、原理的には遅延光路中を無限回廻って光が出
てくるが、ハーフミラーの反射率や反射部材の反射率等
から、ハーフミラー反射率をを３３％から５０％程度に
設定することが一般的である。この様な反射率に設定す
ることで、１パーセント程度の光エネルギーまで取る
と、光遅延素子をおおむね２回から３回廻って出てくる
光まで使用することが出来る。2. Description of the Related Art A conventional illumination optical device is disclosed, for example, in Japanese Patent Application Laid-Open No. 1-187759. Generally, assuming that the half width of the laser light source is Δλ and the wavelength is λ,
The temporal coherence length (coherence length) tc is given by tc = λ 2 / Δλ. At the wavelength λ = 248 nm, the half width Δλ = 0.
In the case of 8 pm, the temporal coherence length tc = 77 mm, and in the case of the wavelength λ = 248 nm and the half width Δλ = 0.6 pm, the temporal coherence length tc = 103 mm.
Conventionally, as shown in FIG. 10, an optical delay element composed of a half mirror and a reflecting member is inserted into an optical path to provide an optical path difference longer than the coherence length, thereby reducing coherence. Was being measured. In principle, an optical delay element emits light in an infinite number of turns in the delay optical path. However, the half mirror reflectivity is set to about 33% to 50% based on the reflectivity of the half mirror and the reflectivity of the reflecting member. It is common to set to By setting such a reflectivity, if light energy of about 1% is obtained, light that comes out of the optical delay element approximately two to three times can be used.
【０００３】[0003]
【発明が解決しようとする課題】上述の様に、従来で
は、コヒーレンス長として、光源全体のスペクトル分布
から求めた値を用いていた。しかしながら、エキシマレ
ーザー光源を用い、一様な照明を得ようとした場合、上
述の様なコヒーレンシー低減手段を用いても、期待通り
の一様な照明が得られないことが判明した。As described above, conventionally, a value obtained from the spectral distribution of the entire light source has been used as the coherence length. However, when it was attempted to obtain uniform illumination using an excimer laser light source, it was found that uniform illumination as expected could not be obtained even when the above-described coherency reduction means was used.
【０００４】本発明は、上記の問題点に鑑み、エキシマ
レーザー光源を使用した場合でも、十分なコヒーレンシ
ーの低減を行うことのできる照明光学装置及びそれを用
いた露光装置を提供することを目的とする。[0004] In view of the above problems, an object of the present invention is to provide an illumination optical apparatus capable of sufficiently reducing coherency even when an excimer laser light source is used, and an exposure apparatus using the same. I do.
【０００５】[0005]
【課題を解決するための手段】本発明では、上記目的を
達成するために、微小コヒーレント素光源が多数集まっ
て形成されたコヒーレント光源と、該コヒーレント光源
からの光束を分割し、分割された一方の光束を遅延光路
に廻し、再び分割した光路に戻す光遅延素子と、を有す
る照明光学系において、前記光遅延素子の遅延光路の光
路長を、前記微小コヒーレント素光源の可干渉長以上に
設定する事を特徴とする照明光学装置を提供する。ま
た、この照明光学装置を備えた露光装置及び露光方法を
提供する。According to the present invention, in order to achieve the above object, a coherent light source formed by gathering a large number of minute coherent elementary light sources, a light beam from the coherent light source is divided, and An optical delay element for turning the light flux to the delay optical path and returning to the split optical path again, wherein the optical path length of the delay optical path of the optical delay element is set to be equal to or longer than the coherence length of the micro coherent elementary light source. An illumination optical device is provided. Further, an exposure apparatus and an exposure method provided with the illumination optical device are provided.
【０００６】更に、本発明では、コヒーレント光源と、
該コヒーレント光源からの光束を分割し、分割された一
方の光束を遅延光路に廻し、再び分割した光路に戻す光
遅延素子と、を有する照明光学系において、前記光遅延
素子は、光束を分割するための光束分割部材と、該光束
分割部材からの光束が入射する反射部材と、を有し、前
記光束分割部材の入射面は、前記反射部材の入射面に対
し直交するように配置されることを特徴とする照明光学
装置をも提供する。Further, according to the present invention, a coherent light source;
An optical delay element that splits a light beam from the coherent light source, sends one of the split light beams to a delay optical path, and returns the split light beam to the split optical path again, wherein the optical delay element splits the light beam A light-splitting member, and a reflecting member to which a light beam from the light-splitting member is incident, wherein an incident surface of the light-splitting member is arranged to be orthogonal to an incident surface of the reflecting member. There is also provided an illumination optical device characterized by the above.
【０００７】[0007]
【発明の実施の形態】エキシマレーザーは、スペクトル
分布の半値幅を狭くする為に、回折格子（グレーティン
グ）Ｇを用いている。この様に、グレーティングＧを内
部に有しているレーザー光源の場合には、図９に示すよ
うに、分光部分の射出スリットＳ上（例えば、図９
（ａ）の＋ｐ／２、０、−ｐ／２位置）に、波長分布が
生じる。つまり、分光部分の射出スリット上に形成され
た微小な光源のスペクトル分布が多数集まって、光源全
体のスペクトル分布が形成されている。DESCRIPTION OF THE PREFERRED EMBODIMENTS An excimer laser uses a diffraction grating (grating) G in order to narrow the half width of a spectrum distribution. As described above, in the case of the laser light source having the grating G therein, as shown in FIG.
A wavelength distribution occurs at (+ p / 2, 0, -p / 2 positions in (a)). That is, a large number of minute light source spectral distributions formed on the exit slit of the light splitting portion form a spectral distribution of the entire light source.
【０００８】この様に、微小な素光源が多数集まって形
成されていると考えられる光源の場合で、隣合う微小な
光源が分離して観察できる空間分解能ｐ（これはエキシ
マレーザーの発散角ωからおおよそ推定でき、ｐ〜λ／
ωである）がスリット幅Ｐよりも細かい（小さい）とき
には、可干渉長を、この空間分解能内での波長分布Δλ
ｐから求まる可干渉長ｔｃｐ ｔｃｐ＝λ2 ／Δλｐ で考える必要がある。（ここで、ｔｃ＜ｔｃｐであ
る。）その理由は、遅延素子によって、このスリットの
像が多数生成されると、遅延の光路長がスリットの全波
長分布から決まる可干渉長ｔｃでしかない場合、各スリ
ット像の任意の空間分解能サイズからの光は互いに干渉
するからである。そしてこの干渉に因って被照射面上に
干渉縞やスペックルを発生する事になる。As described above, in the case of a light source which is considered to be formed by gathering a large number of minute elementary light sources, the spatial resolution p (which is the divergence angle ω of the excimer laser) allows adjacent minute light sources to be separately observed. Can be roughly estimated from
ω) is smaller (smaller) than the slit width P, the coherence length is determined by the wavelength distribution Δλ within this spatial resolution.
It is necessary to consider the coherence length tcp obtained from p tcp tcp = λ 2 / Δλp. (Here, tc <tcp.) The reason is that when a large number of images of the slit are generated by the delay element, the delay optical path length is only the coherent length tc determined from the entire wavelength distribution of the slit. This is because light from an arbitrary spatial resolution size of each slit image interferes with each other. Then, interference fringes and speckles are generated on the irradiated surface due to the interference.
【０００９】例えば、従来の技術のところで述べたエキ
シマレーザーの場合、半値幅Δλ＝０．８ｐｍの場合は
ｔｃｐ＝１５４ｍｍとなり、半値幅Δλ＝０．６ｐｍの
場合はｔｃｐ＝２０６ｍｍになる。本発明では、光遅延
素子の遅延光路の光路長を、コヒーレント光源のスリッ
トの空間分解能内の光の波長分布で決まる可干渉長ｔｃ
ｐより長くする事により、または被照射面であるレチク
ルと共役な光源近傍の位置での空間分解能内の光の波長
分布で決まる可干渉長ｔｃｐより長くする事により、照
明むらを無くすことが出来る。For example, in the case of the excimer laser described in the description of the prior art, when the half width Δλ = 0.8 pm, tcp = 154 mm, and when the half width Δλ = 0.6 pm, tcp = 206 mm. In the present invention, the optical path length of the delay optical path of the optical delay element is determined by the coherence length tc determined by the wavelength distribution of light within the spatial resolution of the slit of the coherent light source.
Illumination unevenness can be eliminated by making the length longer than p, or by making the length longer than the coherence length tcp determined by the wavelength distribution of light within the spatial resolution at a position near the light source conjugate with the reticle that is the irradiation surface. .
【００１０】尚、上記説明では、分光部分の射出スリッ
ト上に波長分布が生じる、と説明したが、射出光束が波
長分布を生じるような特性となっいればよい。また、上
記説明では、エキシマレーザーを例に採ったが、エキシ
マレーザーのみならず、微視的にコヒーレント素光源が
多数集まって形成された特性のコヒーレント光源であれ
ば、本発明を適用することが有効であり、コヒーレンス
の低減を行うことができる。In the above description, it is described that a wavelength distribution is generated on the exit slit of the beam splitting portion. However, it is sufficient that the emitted light beam has a characteristic that produces a wavelength distribution. In the above description, an excimer laser is taken as an example, but the present invention can be applied not only to an excimer laser but also to a coherent light source having a characteristic formed by gathering a large number of coherent elementary light sources microscopically. It is effective and can reduce coherence.
【００１１】[0011]
【実施例】以下に、本発明による照明光学装置の基本的
配置の実施例を、図１を参照しながら説明する。ここに
示す実施例の照明光学装置は、光路順に、エキシマレー
ザー１、デポラライザー３、第１の光遅延素子４、第２
の光遅延素子５及びフライアイオプティカルインテグレ
ータ７を配置している。尚、これらの素子の間には、照
明光学装置のチャンバー内の空間を有効に活用するた
め、幾つかミラーが配置されており、光路は折り曲げら
れている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the basic arrangement of the illumination optical device according to the present invention will be described below with reference to FIG. The illumination optical device of the embodiment shown here includes an excimer laser 1, a depolarizer 3, a first optical delay element 4, a second optical delay
The optical delay element 5 and the fly-eye optical integrator 7 are arranged. Some mirrors are arranged between these elements in order to effectively utilize the space in the chamber of the illumination optical device, and the optical path is bent.
【００１２】デポラライザー３は、図２に示すように、
偏光ビームスプリッタ３１、３４及び反射ミラー３２、
３３からなっている。偏光ビームスプリッタ３１は入射
光線を、Ｐ偏光及びＳ偏光に分離して射出する。そし
て、Ｐ偏光は、偏光ビームスプリッタ３１、偏光ビーム
スプリッタ３４の順に進行し、Ｓ偏光は、偏光ビームス
プリッタ３１、反射ミラー３２、反射ミラー３３、偏光
ビームスプリッタ３１の順に進行する。ここで、偏光ビ
ームスプリッタ３１及び３４は、石英基板等に薄膜を施
し、入射角がほぼブリュースターアングル５６．５度か
ら、薄膜の設計によっては６５度近傍までなるように傾
けて使用し、主にＳ偏光を反射させＰ偏光を透過させ
る。さらに、反射したＳ偏光を、反射ミラー３１で光路
を光路長が前記のスリットの空間分解能内の波長分布で
きまるコヒーレンス長ｔｃｐ＝１５４ｍｍ以上になる距
離分だけ離してある。そして、Ｓ及びＰの両偏光は、ビ
ームスプリッタ３４で再び同一光路に戻る。The depolarizer 3 is, as shown in FIG.
Polarizing beam splitters 31, 34 and reflecting mirror 32,
It consists of 33. The polarization beam splitter 31 separates an incident light beam into P-polarized light and S-polarized light and emits the separated light. The P-polarized light travels in the order of the polarization beam splitter 31 and the polarization beam splitter 34, and the S-polarized light travels in the order of the polarization beam splitter 31, the reflection mirror 32, the reflection mirror 33, and the polarization beam splitter 31. Here, the polarizing beam splitters 31 and 34 are formed by applying a thin film to a quartz substrate or the like, and are used by being inclined so that the incident angle is substantially from 56.5 degrees to Brewster angle to near 65 degrees depending on the design of the thin film. To reflect S-polarized light and transmit P-polarized light. Further, the reflected S-polarized light is separated from the optical path by the reflecting mirror 31 by a distance such that the optical path length is equal to or longer than the coherence length tcp = 154 mm, which is a wavelength distribution within the spatial resolution of the slit. Then, both the S and P polarized lights return to the same optical path again by the beam splitter 34.
【００１３】このデポラライザー３の働きでＰ偏光とＳ
偏光とは振幅の干渉作用が無くなるが、Ｐ偏光、Ｓ偏光
からそれぞれ派生した円偏光同士、楕円偏光同士も振幅
の干渉が無くなる。そのため、不図示のウエハ上でもデ
ポラライズされた状態が達成できる。デポラライザー３
の調整は、一般には、単体ではオートコリメータを使用
して、角度を合わせている。そのため反射ミラーの表面
にはエキシマ光を反射する反射膜を蒸着し、裏面には可
視光を反射する反射膜を蒸着する。この様な反射膜を蒸
着した反射ミラーを用いることで、従来のように、デポ
ラライザー部分を抜き出して調整し、再び光路中へ戻す
といった工程を無くすことができる。この様に、本実施
例中のデポラライザー３の調整は、光路に配置したまま
オートコリメータによる調整を行うことができる。偏光
度の調整は全体を光軸回りに回転させることで調整す
る。By the operation of the depolarizer 3, P-polarized light and S-polarized light
The interference of the amplitude with the polarized light is eliminated, but the interference of the amplitude is also eliminated between the circularly polarized light and the elliptically polarized light respectively derived from the P-polarized light and the S-polarized light. Therefore, a depolarized state can be achieved even on a wafer (not shown). Depolarizer 3
In general, the angle is adjusted by using an autocollimator alone. Therefore, a reflective film that reflects excimer light is deposited on the surface of the reflective mirror, and a reflective film that reflects visible light is deposited on the back surface. By using a reflection mirror on which such a reflection film is deposited, it is possible to eliminate the step of extracting and adjusting the depolarizer portion and returning it to the optical path as in the related art. As described above, the adjustment of the depolarizer 3 in the present embodiment can be performed by the autocollimator while being arranged in the optical path. The degree of polarization is adjusted by rotating the whole around the optical axis.
【００１４】光遅延素子４は、図３（ａ）に示すよう
に、ハーフミラー４１及び３枚の反射ミラー４１、４
２、４３で構成され、ハーフミラー４０を反射した光と
透過した光とで２ｄの光路差が生じるように配置されて
いる。このようにすれば、分割された波連において偏光
を除去でき、コヒーレンシーを低減できるようになるか
らである。また、本実施例では、ハーフミラー４１を最
初に透過する光線を基本光線としている。ここで、ハー
フミラー４１の反射率は、平均で３３％から５０％程度
である。The optical delay element 4 includes a half mirror 41 and three reflection mirrors 41, 4 as shown in FIG.
The light reflected by the half mirror 40 and the light transmitted therethrough are arranged so that an optical path difference of 2d is generated. This is because the polarization can be removed from the divided wave train and the coherency can be reduced. In the present embodiment, a light ray that first transmits through the half mirror 41 is used as a basic light ray. Here, the reflectance of the half mirror 41 is about 33% to 50% on average.
【００１５】さらに、第２の光遅延素子５は、図３
（ｂ）に示すように、ハーフミラー５１及び３枚の反射
ミラー５２、５３、５３で構成され、６ｄの光路差が生
じるように設定してある。また、第１の光遅延素子４同
様に、ハーフミラー５１を最初に透過する光線を基本光
線としている。このように、第１の光遅延素子４の遅延
光路長と第２の光遅延素子５の遅延光路長とを設定すれ
ば、表２に示すように、９つの分割光において光路差が
同一とならないように出来る。このように、ほぼ光を時
間的に、１パーセント以上の光なら、９分割することで
コヒーレンシーの低減がはかれる。０．１パーセント以
上の光なら、１８分割することが好ましい。Further, the second optical delay element 5 is provided in FIG.
As shown in (b), it is composed of a half mirror 51 and three reflecting mirrors 52, 53, 53, and is set so that an optical path difference of 6d is generated. Further, similarly to the first optical delay element 4, a light ray that first transmits through the half mirror 51 is used as a basic light ray. As described above, if the delay optical path length of the first optical delay element 4 and the delay optical path length of the second optical delay element 5 are set, as shown in Table 2, the optical path difference is the same in the nine divided lights. You can avoid it. In this way, if the light is substantially 1% or more in time, coherency can be reduced by dividing the light into nine. If the light is 0.1% or more, it is preferable to divide the light into 18 parts.
【００１６】[0016]
【表１】 [Table 1]
【００１７】さらに、図４に示すように、両光遅延素子
の光入射方位を第１と第２とで直交させ、しかも、一回
中を通るたびに角度θが付く様に設定すると、フライア
イ６に入射する光束は、ほぼ１パーセント以上で９つの
光に分割される。これによりエネルギーが低減されるだ
けでなく、ウエハ上でのスペックルをシフトさせる効果
がある。Further, as shown in FIG. 4, when the light incidence directions of the two optical delay elements are set to be orthogonal to each other in the first and second directions, and are set so that the angle θ is given each time the light passes through the optical delay element, The luminous flux incident on the eye 6 is split into nine lights at approximately 1% or more. This not only reduces energy but also has the effect of shifting speckle on the wafer.
【００１８】また、ハーフミラーの反射率はＰ偏光入射
とＳ偏光入射とでは異なるため、図５に示す様に、方位
を直交させることで、第１と第２の合成の反射率はＰ偏
光とＳ偏光とでほぼ同じになる。従って、フライアイに
入射する光束の偏光状態はあまり変化しないという効果
もある。さらに、図６に示す様に、直接光ｂと反射光ｃ
及びｄとで光のプロファイルが反転するようにしてある
ので、レーザー光のプロファイルを平均化する効果もあ
る。Further, since the reflectance of the half mirror is different between P-polarized light incidence and S-polarized light incidence, as shown in FIG. 5, by making the directions orthogonal, the first and second combined reflectances become P-polarized light. And S-polarized light. Therefore, there is also an effect that the polarization state of the light beam incident on the fly eye does not change much. Further, as shown in FIG. 6, the direct light b and the reflected light c
And d, the light profile is inverted, so that there is also an effect of averaging the laser light profile.
【００１９】第１の光遅延素子４及び第２の光遅延素子
５の反射ミラーは、表面に主波長であるエキシマ光を反
射し、裏面には例えば緑色などの可視光を主に反射する
薄膜が蒸着されている。これは、偏角を調整する時にオ
ートコリメーターを使用して調整するようにするため
で、調整時におのおののミラーを振って調整するが、調
整用の工具ミラーなどを用いると、交換する時にずれが
生じ、偏角が狂う恐れがある。エキシマ光と可視光を反
射するミラーを用いることで、交換する必要が無くな
る。The reflecting mirrors of the first optical delay element 4 and the second optical delay element 5 reflect excimer light, which is the main wavelength, on the front surface and a thin film mainly reflecting visible light such as green on the back surface. Has been deposited. This is to adjust using the auto collimator when adjusting the declination.Each mirror is shaken at the time of adjustment, but if a tool mirror for adjustment is used, it will shift when replacing. May occur and the declination may go wrong. By using a mirror that reflects excimer light and visible light, there is no need for replacement.
【００２０】また、ＫｒＦエキシマレーザーの場合は、
本願出願時点で、反射ミラーを使用できるが、ＡｒＦレ
ーザーやそれ以下の波長の光源の場合、反射率があまり
高くないので、ミラーを使用できない可能性がある。そ
の場合は、図７に示すように、ミラーの代わりに、蛍石
などの４５度プリズム４５、４６、４７、４８、５５、
５６、５７及び、５８を用いて、全反射を利用して光路
を曲げてやればよい。ここで、図７（ｂ）に示すよう
に、光遅延素子の中にリレーレンズ６１及び６２を配置
すると、角度ずれが生じても性能に大きな影響を与えな
い光学系を構成することができる。また、リレーレンズ
の代わりに、ミラー自身を凹面鏡にして、入り口、出口
を共役にしてやれば、同様に、角度ずれが生じても性能
に大きな影響を与えない光学系を構成することができ
る。In the case of a KrF excimer laser,
At the time of filing the present application, a reflecting mirror can be used. However, in the case of an ArF laser or a light source having a wavelength shorter than that, there is a possibility that the mirror cannot be used because the reflectance is not so high. In that case, as shown in FIG. 7, instead of a mirror, a 45-degree prism 45, 46, 47, 48, 55,
The optical path may be bent using the total reflection by using 56, 57, and 58. Here, as shown in FIG. 7B, when the relay lenses 61 and 62 are arranged in the optical delay element, an optical system that does not greatly affect the performance even if an angle shift occurs can be configured. If the mirror itself is replaced by a concave mirror instead of the relay lens and the entrance and exit are conjugated, an optical system that does not greatly affect the performance even if an angle shift occurs can be constructed.
【００２１】更に、詳細な、半導体素子を製造する露光
光装置全体の実施例を以下に示す。図９に示すように、
投影露光装置に配置された照明光学装置の基本配置は前
述の実施例の通りであるが、さらに詳しくは、デポララ
イーザー３と第１の光遅延素子４との間にリレーレンズ
２を設け、第２の光遅延素子６とフライアイオプティカ
ルインテグレータ７との間にエキスパンダー光学系６を
有し、フライアイオプティカルインテグレータ７の射出
側にはコンデンサーレンズ８が配置されている。Further, a detailed embodiment of the entire exposure light apparatus for manufacturing a semiconductor element will be described below. As shown in FIG.
The basic arrangement of the illumination optical device arranged in the projection exposure apparatus is the same as in the above-described embodiment. More specifically, the relay lens 2 is provided between the depolarizer 3 and the first optical delay element 4, and the second An expander optical system 6 is provided between the optical delay element 6 and the fly-eye optical integrator 7, and a condenser lens 8 is arranged on the exit side of the fly-eye optical integrator 7.
【００２２】ここで、エキスパンダー光学系６は、シリ
ンドリカルエキスパンダー及びエキスパンダーから構成
されており、エキシマレーザー１の矩形形状を正方形形
状にしている。また、フライアイオプティカルインテグ
レータ７は、第１フライアイ７１と第２フライアイ７２
とから構成されている。第１フライアイ７１は長方形形
状のフライアイレンズ素子が規則的に配置されたもの
で、第２フライアイ７２は、長方形形状のフライアイレ
ンズ素子が不規則的に配置されたものである。フライア
イオプティカルインテグレータ７を射出した光束は、コ
ンデンサーレンズ８によって、被照射面であるレチクル
９を均一にケーラー照明することになる。そして、投影
対物レンズ１０を介して、露光面であるウエハ１１がレ
チクル９と共役になっており、レチクル９のパターンが
ウエハ１１面上に転写される。そのときの、倍率は、１
／４または１／５が好ましく、実際の露光は、レチクル
９及びウエハ１１を走査して行う。Here, the expander optical system 6 is composed of a cylindrical expander and an expander, and makes the rectangular shape of the excimer laser 1 a square shape. The fly-eye optical integrator 7 includes a first fly-eye 71 and a second fly-eye 72.
It is composed of The first fly-eye 71 has a rectangular fly-eye lens element arranged regularly, and the second fly-eye 72 has a rectangular fly-eye lens element arranged irregularly. The light beam emitted from the fly-eye optical integrator 7 is uniformly Koehler-illuminated by the condenser lens 8 on the reticle 9 to be irradiated. Then, the wafer 11 as an exposure surface is conjugate with the reticle 9 via the projection objective lens 10, and the pattern of the reticle 9 is transferred onto the surface of the wafer 11. At that time, the magnification is 1
/ 4 or ５ is preferable, and actual exposure is performed by scanning the reticle 9 and the wafer 11.
【００２３】ここで、理想的には、スリットの空間分解
能内の光の波長分布で決まる可干渉長ｔｃｐより長くす
る事が望ましいが、被照射面と共役な光源近傍の位置で
の空間分解能内の光の波長分布で決まる可干渉長ｔｃｐ
より長くする事でも良い。というのは、この共役面での
光源像が遅延素子によって重畳されるので、ここでの可
干渉距離ｔｃｐより長ければ、不要な干渉縞やスペック
ルは発生しないからである。また、ここでの可干渉距離
は、一般にはスリット上での可干渉距離よりも短いと考
えられ、より実際的な構成が達成できる。Here, ideally, it is desirable to make the coherence length tcp longer than the coherence length tcp determined by the wavelength distribution of the light within the spatial resolution of the slit. Coherence length tcp determined by wavelength distribution of light
It may be longer. This is because, since the light source image on the conjugate plane is superimposed by the delay element, unnecessary interference fringes and speckles do not occur if the light source image is longer than the coherence distance tcp here. In addition, the coherence distance here is generally considered to be shorter than the coherence distance on the slit, and a more practical configuration can be achieved.
【００２４】[0024]
【発明の効果】以上のように、本発明により、簡単な構
成でコヒーレンシーの低減を十分にに行える事が出来
る。また、エネルギー密度の低減も十分におこなえるこ
とになる。As described above, according to the present invention, coherency can be sufficiently reduced with a simple configuration. In addition, the energy density can be sufficiently reduced.
【図１】図１は、本発明による照明光学装置を示す図で
ある。FIG. 1 is a diagram showing an illumination optical device according to the present invention.
【図２】図２は、本発明によるデポーラライザーを説明
した図である。FIG. 2 is a diagram illustrating a depolarizer according to the present invention.
【図３】図３は、本発明による光遅延素子を説明した図
である。FIG. 3 is a diagram illustrating an optical delay element according to the present invention.
【図４】図４は、本発明による光遅延素子の作用を説明
した図である。FIG. 4 is a diagram illustrating the operation of the optical delay element according to the present invention.
【図５】図５は、本発明によるハーフミラーを示した図
である。FIG. 5 is a diagram showing a half mirror according to the present invention.
【図６】図６は、本発明による光遅延素子の作用を説明
した図である。FIG. 6 is a diagram for explaining the operation of the optical delay element according to the present invention.
【図７】図７は、４５度プリズムを用いた実施例を示し
た図である。FIG. 7 is a diagram showing an embodiment using a 45-degree prism.
【図８】図８は、本発明による露光装置を示した図であ
る。FIG. 8 is a view showing an exposure apparatus according to the present invention.
【図９】図９は、エキシマレーザーの射出光分布を示し
た図である。FIG. 9 is a diagram showing an emission light distribution of an excimer laser.
【図１０】図１０は、従来例の図である。FIG. 10 is a diagram of a conventional example.
１ エキシマレーザー ２ リレーレンズ ３ デポラライザ ４ 第１の光遅延素子 ５ 第２の光遅延素子 ６ エキスパンダー光学系 ７ フライアイオプティカルインテグレータ ８ コンデンサーレンズ ９ レチクル １０ 投影対物レンズ １１ ウエハ Reference Signs List 1 excimer laser 2 relay lens 3 depolarizer 4 first optical delay element 5 second optical delay element 6 expander optical system 7 fly-eye optical integrator 8 condenser lens 9 reticle 10 projection objective lens 11 wafer
Claims (15)
成されたコヒーレント光源と、 該コヒーレント光源からの光束を分割し、分割された一
方の光束を遅延光路に廻し、再び分割した光路に戻す光
遅延素子と、を有する照明光学系において、 前記光遅延素子の遅延光路の光路長を、前記微小コヒー
レント素光源の可干渉長以上に設定する事を特徴とする
照明光学装置。1. A coherent light source formed by gathering a large number of minute coherent elementary light sources, an optical delay that splits a light beam from the coherent light source, sends one of the split light beams to a delay optical path, and returns the split light path to the split optical path again An illumination optical system comprising: an illumination optical system, wherein an optical path length of a delay optical path of the optical delay element is set to be equal to or longer than a coherence length of the minute coherent elementary light source.
一周する毎に、射出される光束の偏角を変化させること
を特徴とする請求項１記載の照明光学装置。2. The illumination optical device according to claim 1, wherein the optical delay element changes the deflection angle of the emitted light beam each time the light beam makes one round of the delay optical path.
の偏角の方向と、前記第２の光遅延素子から射出された
光束の偏角の方向とが、異なることを特徴とする請求項
２記載の照明光学装置。3. A light beam emitted from said first optical delay element and a light beam emitted from said second optical delay element are different in direction of deflection. The illumination optical device according to claim 2.
ー及び複数の反射ミラーを有することを特徴とする請求
項１乃至３記載の照明光学装置。4. The illumination optical device according to claim 1, wherein said optical delay element has a polarization beam splitter and a plurality of reflection mirrors.
とすると、前記第１の光遅延素子は２ｎ×Ｌ、第２の光
遅延素子が６ｎ×Ｌ、第ｍ番目の光遅延素子が２×ｍ＾
２×Ｌの遅延光路を有することを特徴とする請求項１乃
至４記載の照明光学装置。5. The S-polarized light delay distance of the depolarizer is L
Then, the first optical delay element is 2n × L, the second optical delay element is 6n × L, and the m-th optical delay element is 2 × m ＾.
The illumination optical device according to claim 1, further comprising a 2 × L delay optical path.
ための第１の光束分割部材と、該第１の光束分割部材か
らの光束が入射する第１の反射部材を有し、 前記第２の光遅延素子は、光束を分割するための第２の
光束分割部材と、該第２の光束分割部材からの光束が入
射する第２の反射部材を有し、 前記第１の光束分割部材の入射面は、前記第１の反射部
材の入射面に対し直交するように配置され、 前記第２の光束分割部材の入射面は、前記第２の反射部
材の入射面に対し直交するように配置されることを特徴
とする請求項１乃至５記載の照明光学装置。6. The first optical delay element has a first light beam splitting member for splitting a light beam, and a first reflecting member on which a light beam from the first light beam splitting member enters. The second optical delay element includes a second light beam splitting member for splitting a light beam, and a second reflecting member to which a light beam from the second light beam splitting member enters, and wherein the first light beam The incident surface of the splitting member is arranged to be orthogonal to the incident surface of the first reflecting member, and the incident surface of the second light beam splitting member is orthogonal to the incident surface of the second reflecting member. The illumination optical device according to claim 1, wherein the illumination optical device is arranged as follows.
ミラーであり、前記第２の光束分割部材は、第２のハー
フミラーであり、前記第１のハーフミラーと前記第２の
ハーフミラーとは、互いに直交するように設置されるこ
とを特徴とする請求項６記載の照明光学装置。7. The first light beam splitting member is a first half mirror, the second light beam splitting member is a second half mirror, and the first half mirror and the second half mirror are connected to each other. The illumination optical device according to claim 6, wherein the half mirrors are installed so as to be orthogonal to each other.
射ミラーを有する光遅延素子全体を光軸に対して所望の
角度だけ傾けることにより、Ｐ及びＳ偏光を分離するこ
とを特徴とする請求項１乃至７記載の照明光学装置。8. The P and S polarizations are separated by tilting the entire optical delay element having the polarization beam splitter and the plurality of reflection mirrors at a desired angle with respect to the optical axis. 8. The illumination optical device according to 7.
に、前記コヒーレント光源の使用波長を主に反射する薄
膜が形成され、裏面側に、別の波長を主に反射する薄膜
が形成されることを特徴とする請求項１乃至８記載の照
明光学装置。9. The reflection mirror has a thin film mainly reflecting the wavelength used by the coherent light source formed on a front surface side on which light rays are incident, and a thin film mainly reflecting another wavelength formed on a rear surface side. 9. The illumination optical device according to claim 1, wherein:
リズムを有し、全反射を利用して光路を曲げることを特
徴とする請求項１乃至９記載の照明光学装置。10. The illumination optical device according to claim 1, wherein the optical delay element has a prism made of quartz or fluorite, and the optical path is bent using total reflection.
と、投影対物レンズと、物体と、基板と、を有すること
を特徴とする露光装置。11. An exposure apparatus comprising: the illumination optical device according to claim 1; a projection objective lens; an object; and a substrate.
よりマスクを照明し、前記マスクを投影光学系を用いて
ウエハ上に投影露光することを特徴とする露光方法。12. An exposure method, wherein a mask is illuminated by the illumination optical device according to claim 1, and said mask is projected and exposed on a wafer using a projection optical system.
光束を折り曲げて、被照射面上へ光束を導くための反射
ミラーを有する照明光学装置の光路調整方法において、 前記光源から放射される波長と異なる第２の光源を用
い、 前記反射ミラーを微動調整し、 微動調整の終了後、前記第２の光源を取り外し、前記紫
外線を放射する光源に置き換え、 前記反射ミラーは、光線が入射する表面側に、前記光源
の使用波長を主に反射する薄膜が形成され、裏面側に、
別の波長を主に反射する薄膜が形成されていることを特
徴とする照明光学装置の光路調整方法。13. A method for adjusting the optical path of an illumination optical apparatus having a light source that emits ultraviolet light and a reflecting mirror for bending a light beam from the light source and guiding the light beam onto an irradiated surface, wherein the light source emits the light beam. Using a second light source having a different wavelength, finely adjusting the reflection mirror, removing the second light source after completion of the fine adjustment, and replacing the second light source with a light source that emits ultraviolet light. On the front side, a thin film mainly reflecting the wavelength used by the light source is formed, and on the back side,
An optical path adjusting method for an illumination optical device, wherein a thin film mainly reflecting another wavelength is formed.
方の光束を遅延光路に廻し、再び分割した光路に戻す光
遅延素子と、を有する照明光学系において、 前記光遅延素子は、光束を分割するための光束分割部材
と、該光束分割部材からの光束が入射する反射部材と、
を有し、 前記光束分割部材の入射面は、前記反射部材の入射面に
対し直交するように配置されることを特徴とする照明光
学装置。14. An illumination optical system comprising: a coherent light source; and an optical delay element that splits a light beam from the coherent light source, sends one of the split light beams to a delay optical path, and returns the split light beam to the split optical path again. The optical delay element, a light beam splitting member for splitting the light beam, a reflecting member to which the light beam from the light beam splitting member is incident,
An illumination optical device, comprising: an incident surface of the light beam splitting member, which is arranged to be orthogonal to an incident surface of the reflective member.
とを特徴とする請求項１４記載の照明光学装置。15. The illumination optical device according to claim 14, wherein a plurality of said optical delay elements are arranged.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10117434A JPH11312631A (en) | 1998-04-27 | 1998-04-27 | Illuminating optical device and aligner |
| US09/300,660 US6238063B1 (en) | 1998-04-27 | 1999-04-27 | Illumination optical apparatus and projection exposure apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10117434A JPH11312631A (en) | 1998-04-27 | 1998-04-27 | Illuminating optical device and aligner |
Related Child Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2007141206A Division JP4548449B2 (en) | 2007-05-29 | 2007-05-29 | Illumination optical apparatus and exposure apparatus |
| JP2007141207A Division JP4534210B2 (en) | 2007-05-29 | 2007-05-29 | Optical delay device, illumination optical device, exposure apparatus and method, and semiconductor device manufacturing method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11312631A true JPH11312631A (en) | 1999-11-09 |
Family
ID=14711560
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10117434A Pending JPH11312631A (en) | 1998-04-27 | 1998-04-27 | Illuminating optical device and aligner |
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