JP3287334B2

JP3287334B2 - Laser beam harmonic generator, exposure apparatus, laser beam harmonic generation method, exposure method using the same, and device manufacturing method using the same

Info

Publication number: JP3287334B2
Application number: JP14002199A
Authority: JP
Inventors: 祥司石坂; 秀雄原; 裕市原
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 1999-05-20
Filing date: 1999-05-20
Publication date: 2002-06-04
Anticipated expiration: 2017-06-04
Also published as: JPH11354439A

Description

DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【産業上の利用分野】本発明は、露光装置の光源に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source for an exposure apparatus.

【０００２】[0002]

【従来の技術】従来、半導体素子の製造に使用されてい
る露光装置の光源としては、主として超高圧水銀ランプ
が用いられてきた。しかし、近年、半導体素子は高集積
化、微細化の一途を辿り、光学的な露光方式も高解像力
のレンズの開発等で益々その領域を拡げつつある。この
種の露光装置において、マスク又はレチクルの回路パタ
ーンをウェハ上に転写、焼付ける場合、ウェハ上に焼き
付けられる回路パターンの解像線幅は光源から露光光の
波長に比例するため、近年では、上述の超高圧水銀ラン
プに代わってＫｒＦエキシマレーザが利用されている。
また、金属蒸気レーザ等のパルスレーザを非線形光学結
晶等の高調波を発生する物質に照射して得られる高調波
光の利用も検討されている。2. Description of the Related Art Conventionally, an ultra-high pressure mercury lamp has been mainly used as a light source of an exposure apparatus used for manufacturing a semiconductor device. However, in recent years, semiconductor devices have continued to be highly integrated and miniaturized, and the optical exposure system has been expanding its area by developing lenses having high resolution. In this type of exposure apparatus, when a circuit pattern of a mask or a reticle is transferred onto a wafer and printed, the resolution line width of the circuit pattern printed on the wafer is proportional to the wavelength of exposure light from a light source. A KrF excimer laser is used in place of the above-mentioned ultra-high pressure mercury lamp.
In addition, use of harmonic light obtained by irradiating a material that generates harmonics, such as a nonlinear optical crystal, with a pulse laser such as a metal vapor laser is also being studied.

【０００３】[0003]

【発明が解決しようとする課題】しかし、エキシマレー
ザを用いた露光装置には様々な問題点があることが判明
した。まず、例えば安定共振器型のエキシマレーザを考
えると、このレーザはスペクトル幅がΔλ＝０．４ｎｍ
と広く（つまり単色性が悪く）、石英のみの単色レンズ
を投影光学系として使う場合には波長の狭帯化が必要で
ある。また、エキシマレーザ共通の問題として、寿命が
短く、フッ素等の有毒ガスを使うことによるメンテナン
ス性の困難さが挙げられる。However, it has been found that an exposure apparatus using an excimer laser has various problems. First, for example, considering a stable resonator type excimer laser, this laser has a spectral width Δλ = 0.4 nm.
Therefore, when a monochromatic lens made of only quartz is used as a projection optical system, it is necessary to narrow the wavelength band. In addition, problems common to excimer lasers include short lifetime and difficulty in maintenance due to the use of toxic gas such as fluorine.

【０００４】これらの問題点を回避するためにパルスレ
ーザの高調波が検討されている。第２高調波発生には、
反転対称性のない誘電体の単結晶（非線形光学結晶等）
が用いられる。この反転対称性のない誘電体の単結晶か
ら第２高調波を発生させるには、位相整合条件（基本波
と第２高調波に対する結晶）の屈折率が等しくなる条
件）を満たす必要があり、そのためにはレーザ光をある
特定の角度から入射させなければならない。因みに、位
相整合条件が満足されない場合は発生する高調波の発生
効率が悪くなる。また、第２高調波の発生効率を上げる
ためには、レーザビームの単位面積当たりのエネルギー
密度を大きくする必要がある。しかし、結晶中でレーザ
ビームを集光させればさせるほど結晶はレーザビームを
吸収し、それによって発生する熱によって結晶中の温度
分布（温度勾配）が急峻になる。この温度変化により結
晶の屈折率が変化するので位相整合条件を満たさなくな
ってしまう。さらに、結晶の単位面積当たり、及び単位
時間当たりのレーザビームの投入パワーが増すにつれ結
晶の寿命が著しく短くなる。加えて、レーザ光から発生
する第２高調波はコヒーレンシーが高いのでスペックル
や干渉縞等の不要な干渉パターンが生じてしまうといっ
た問題点が生じた。[0004] In order to avoid these problems, harmonics of pulsed lasers have been studied. For the second harmonic generation,
Single crystal of dielectric without inversion symmetry (nonlinear optical crystal, etc.)
Is used. In order to generate the second harmonic from a dielectric single crystal having no inversion symmetry, it is necessary to satisfy a phase matching condition (a condition in which the refractive index of the fundamental wave and the crystal for the second harmonic are equal). For that purpose, the laser light must be incident from a specific angle. Incidentally, when the phase matching condition is not satisfied, the generation efficiency of the generated harmonics becomes poor. Further, in order to increase the generation efficiency of the second harmonic, it is necessary to increase the energy density per unit area of the laser beam. However, the more the laser beam is condensed in the crystal, the more the crystal absorbs the laser beam, and the heat generated thereby makes the temperature distribution (temperature gradient) in the crystal steeper. Since the refractive index of the crystal changes due to the temperature change, the phase matching condition cannot be satisfied. Furthermore, the life of the crystal is significantly shortened as the input power of the laser beam per unit area and per unit time of the crystal is increased. In addition, the second harmonic generated from the laser beam has a high coherency, so that an unnecessary interference pattern such as speckle or interference fringe occurs.

【０００５】本発明は、これらの問題点を解決し、高効
率、長寿命の安定した高調波を発生する高調波発生装置
を提供することにある。An object of the present invention is to solve the above problems and to provide a harmonic generation device which generates stable harmonics with high efficiency and long life.

【０００６】[0006]

【課題を解決するための手段】上記問題点解決のため請
求項１に記載の発明では、レーザ光（ＬＢ）を発生する
レーザ光源（１）と、該レーザ光が照射されることによ
り、該レーザ光の高調波光を発生する高調波発生手段
（４）と、該レーザ光源と該高調波発生手段との間に配
置され、該レーザ光の光路を、該光路に対してほぼ垂直
な方向に変位させる光路変位手段としての振動鏡（２）
と、該振動鏡と該高調波発生手段との間に配置され、該
振動鏡で反射された該レーザ光を集光して該高調波発生
手段に照射するレンズ（３）とを高調波発生装置に構成
するとともに、該振動鏡の振動中心を該レンズの前側焦
点に配置した。According to the first aspect of the present invention, there is provided a laser light source (1) for generating a laser beam (LB), and the laser beam is irradiated by the laser light source (1). a harmonic generation unit generating a harmonic light of a laser beam (4), distribution between the laser light source and the harmonic generating unit
And the optical path of the laser light is substantially perpendicular to the optical path.
Vibrating mirror as optical path displacement means for displacing in various directions (2)
Disposed between the vibrating mirror and the harmonic generating means,
Focusing the laser light reflected by the vibrating mirror to generate the harmonic
A lens (3) for irradiating the means into a harmonic generator
And the center of vibration of the vibrating mirror is focused on the front side of the lens.
Placed at the point .

【０００７】また請求項２に記載の発明では、レーザ光
（ＬＢ）を発生するレーザ光源（１）と、該レーザ光が
照射されることにより、該レーザ光の高調波光を発生す
る高調波発生手段（４）と、該レーザ光源と該高調波発
生手段との間に配置され、該レーザ光の光軸に対して傾
斜可能であり、該傾斜により前記レーザ光の光路を該光
路に対してほぼ垂直な方向に変位させる光路変位手段と
しての平行平板ガラス（１５）と、該レーザ光源と該平
行平板ガラスとの間に配置され、前記レーザ光を集光す
るレンズ（３）と、をレーザ光の高調波発生装置に構成
した。According to the second aspect of the present invention, a laser light source (1) for generating laser light (LB) and the laser light
Irradiation generates harmonic light of the laser light.
Harmonic generating means (4), the laser light source and the harmonic generating means.
Between the laser light source and the optical axis of the laser light.
The laser beam can be inclined by changing the optical path of the laser light.
Optical path displacement means for displacing in a direction substantially perpendicular to the path;
Parallel plate glass (15), the laser light source and the flat
It is arranged between a row and a flat glass and focuses the laser light.
Lens (3) and a laser beam harmonic generator
I did .

【０００８】また請求項８に記載の発明では、レーザ光
（ＬＢ）を発生するレーザ光源（１）と、レーザ光が照
射されることによりレーザ光の高調波光を発生する高調
波発生手段（４）とを備え、レーザ光の高調波光をマス
ク（１２）に照射することによって、マスク上のパター
ンを基板（１４）上に露光する露光装置に、レーザ光源
と高調波発生手段との間に配置され、レーザ光の光路
を、その光路に対してほぼ垂直な方向に変位させる光路
変位手段としての振動鏡（２）と、振動鏡と高調波発生
手段との間に配置され、その振動鏡で反射されたレーザ
光を集光して高調波発生手段に照射するレンズ（３）と
を構成するとともに、振動鏡の振動中心は、レンズの前
側焦点に配置することとした。According to the invention described in claim 8, the laser light
(LB) and a laser light source (1).
Higher harmonics that generate higher harmonics of laser light when radiated
And a wave generating means (4) for massaging the harmonic light of the laser light.
By irradiating the mask (12), the pattern on the mask
An exposure apparatus for exposing a substrate on a substrate (14) is provided with a laser light source.
And an optical path of the laser light
Is displaced in a direction substantially perpendicular to the optical path.
Vibrating mirror (2) as displacement means, vibrating mirror and harmonic generation
Laser placed between the means and reflected by its vibrating mirror
A lens (3) for condensing light and irradiating it to the harmonic generation means;
And the center of vibration of the vibrating mirror is in front of the lens.
It was arranged at the side focus .

【０００９】また請求項９に記載の発明では、レーザ光
（ＬＢ）を発生するレーザ光源（１）と、レーザ光が照
射されることによりレーザ光の高調波光を発生する高調
波発生手段（４）とを備え、レーザ光の高調波光をマス
ク（１２）に照射することによって、マスク上のパター
ンを基板（１４）上に露光する露光装置に、レーザ光源
と高調波発生手段との間に配置され、レーザ光の光軸に
対して傾斜可能であり、その傾斜によりレーザ光の光路
を該光路に対してほぼ垂直な方向に変位させる光路変位
手段としての平行平板ガラス（１５）と、レーザ光源と
平行平板ガラスとの間に配置され、前記レーザ光を集光
するレンズ（３）とを構成した。According to the ninth aspect of the present invention, the laser light
(LB) and a laser light source (1).
Higher harmonics that generate higher harmonics of laser light when radiated
And a wave generating means (4) for massaging the harmonic light of the laser light.
By irradiating the mask (12), the pattern on the mask
An exposure apparatus for exposing a substrate on a substrate (14) is provided with a laser light source.
Between the laser beam and the harmonic generation means.
The laser beam can be tilted with respect to the optical path of the laser beam.
Optical path displacement for displacing in a direction substantially perpendicular to the optical path
Parallel plate glass (15) as a means and a laser light source
It is placed between parallel flat glass and focuses the laser light
Lens (3) .

【００１０】また請求項１６に記載の発明では、レーザ
光源（１）から発生したレーザ光（ＬＢ）を高調波発生
手段（４）に照射して、該レーザ光の高調波を発生する
方法であって、レーザ光源と高調波発生手段との間に配
置された振動鏡（２）により、レーザ光の光路を、該光
路に対してほぼ垂直な方向に変位させ、振動鏡と高調波
発生手段との間に配置されたレンズ（３）により、該レ
ンズの前側焦点に振動中心が配置された該振動鏡にて反
射された前記レーザ光を集光して、該高調波発生手段に
照射することとした。Further, according to the present invention, a laser is provided.
Harmonic generation of laser beam (LB) generated from light source (1)
Irradiating the means (4) to generate harmonics of the laser light
A method comprising disposing between a laser light source and a harmonic generation means.
The optical path of the laser light is changed by the placed vibrating mirror (2).
Displacement in a direction almost perpendicular to the road, vibrating mirror and harmonic
The lens (3) disposed between the lens and the generating means makes the lens
With the vibrating mirror whose vibration center is located at the front focal point of the lens.
The emitted laser light is condensed and applied to the harmonic generation means.
Irradiation was performed .

【００１１】また請求項１７に記載の発明では、レーザ
光源（１）から発生したレーザ光（ＬＢ）を高調波発生
手段（４）に照射して、該レーザ光の高調波を発生する
方法であって、レーザ光源と高調波発生手段との間に配
置され、且つレーザ光の光軸に対し傾斜可能な平行平板
ガラス（１５）により、該レーザ光の光路を、該光路に
対してほぼ垂直な方向に変位させ、レーザ光源と平行平
板ガラスとの間に配置された集光レンズ（３）により、
レーザ光を集光して該平行平板ガラスに照射することと
した。Further, according to the present invention, a laser is provided.
Harmonic generation of laser beam (LB) generated from light source (1)
Irradiating the means (4) to generate harmonics of the laser light
A method comprising disposing between a laser light source and a harmonic generation means.
Parallel plate that is placed and tiltable with respect to the optical axis of the laser beam
By the glass (15), the optical path of the laser light is changed to the optical path.
It is displaced in the direction substantially perpendicular against, parallel to the laser light source Rights
By the condenser lens (3) arranged between the glass plate and
Converging the laser beam and irradiating the parallel plate glass
I did .

【００１２】[0012]

【００１３】[0013]

【００１４】[0014]

【００１５】[0015]

【００１６】[0016]

【００１７】[0017]

【作用】本願の各項に記載の発明によれば、レーザ光Ｌ
Ｂの光路を変位させて高調波発生手段（結晶４）への照
射位置を変更しているので、レーザ光とレーザ光の高調
波が結晶に吸収されることにより発生する熱が均等に生
じ、結晶４中の温度分布が急峻にならない。従って温度
変化による結晶４の屈折率変化が生じないので位相整合
条件が満足され、高調波の発生効率が上がる。また結晶
４の単位面積当たりに照射されるレーザ光ＬＢの強度が
単位時間でみると著しく減少することになるので結晶４
の寿命も延びることになる。 According to the invention described in each item of the present application , the laser light L
Since the optical path of B is displaced to change the irradiation position on the harmonic generating means (crystal 4), the laser light and the harmonics of the laser light are absorbed by the crystal, and the heat generated uniformly occurs. The temperature distribution in the crystal 4 does not become steep. Therefore, since the refractive index of the crystal 4 does not change due to the temperature change, the phase matching condition is satisfied, and the generation efficiency of harmonics increases. In addition, the intensity of the laser beam LB applied per unit area of the crystal 4 significantly decreases in a unit time, so that the crystal 4
Will also extend the lifespan.

【００１８】また高調波発生手段（結晶４）に入射する
レーザ光の入射角をほぼ一定に維持した状態で、レーザ
光ＬＢの光路を変位させるようにすれば、入射レーザ光
に対する結晶の方位角を保持することができ（レーザ光
の偏光方向と結晶軸との角度関係を一定に保つことがで
き）、高調波の発生効率の低下を防止することができ
る。Further, it is incident on the harmonic generation means (crystal 4).
With the incident angle of the laser beam kept almost constant,
By displacing the optical path of the light LB, the azimuth angle of the crystal with respect to the incident laser light can be maintained (the angular relationship between the polarization direction of the laser light and the crystal axis can be kept constant), and the harmonic Can be prevented from lowering the generation efficiency.

【００１９】また本願の各項に記載の発明によれば、結
晶４の直前に配置された光学部材（例えば図１、３のレ
ンズ３）へのレーザ光の照射位置も変位することができ
るので、このような光学部材の単位面積当たりに照射さ
れるレーザ光ＬＢの強度が単位時間でみると著しく減少
でき、光学部材の寿命も延ばすことが可能となる。 According to the invention described in each section of the present application, the irradiation position of the laser beam on the optical member (for example, the lens 3 in FIGS. 1 and 3) disposed immediately before the crystal 4 can also be displaced. The intensity of the laser beam LB applied per unit area of such an optical member can be significantly reduced in a unit time, and the life of the optical member can be extended.

【００２０】また請求項１、８、１６に記載の発明によ
れば、振動鏡２の振動中心をレンズ３の前側焦点に配置
したので、レンズ３の像側ではレーザ光ＬＢは光軸に平
行に振動し、これにより高調波発生手段（非線形光学結
晶４）に入射するレーザ光の入射角を常にほぼ一定にす
ることができる。このため位相整合条件が満足され、高
調波の発生効率が上がる。According to the first, eighth and sixteenth aspects of the present invention, since the center of vibration of the vibrating mirror 2 is located at the front focal point of the lens 3, the laser beam LB is parallel to the optical axis on the image side of the lens 3. Accordingly, the incident angle of the laser beam incident on the harmonic generation means (nonlinear optical crystal 4) can be made substantially constant at all times. For this reason, the phase matching condition is satisfied, and the generation efficiency of harmonics increases.

【００２１】また請求項２、９、１７に記載の発明によ
れば、レーザ光源１と平行平板ガラス１５との間に、レ
ーザ光を集光するレンズ３を設けたので、レーザ光は高
調波発生手段（非線形光学結晶４）内に集光され、且つ
光軸と平行に変位させることができる。このため結晶４
に入射するレーザ光の入射角を常にほぼ一定にすること
ができる。このため位相整合条件が満足され、高調波の
発生効率が上がる。[0021] According to the invention described in claim 2,9,17, between the laser light source 1 and the flat row plate glass 15, since the laser beam is provided a lens 3 for focusing the laser beam is a harmonic The light is focused in the wave generating means (non-linear optical crystal 4) and can be displaced in parallel with the optical axis. Therefore, crystal 4
The incident angle of the laser beam incident on the laser beam can always be made substantially constant. For this reason, the phase matching condition is satisfied, and the generation efficiency of harmonics increases.

【００２２】[0022]

【発明の実施形態】図１は、本発明の第１の実施形態に
よる高調波発生装置を示す図である。銅蒸気レーザ１か
ら発生したレーザ光ＬＢは、不図示のビームエキスパン
ダ等により所定の断面積を持ったビームに整形された
後、図面に平行な面内で振動するガルバノミラー等の振
動鏡２によって振られる。振られたレーザ光ＬＢはレン
ズ群３で集光して非線形光学結晶４（本実施形態ではβ
−Ｂ４Ｂ２Ｏ４）に照射される。このとき、振動鏡２の
振動中心をレンズ群３の前側焦点に配置すればレンズ群
３の像側ではレーザ光ＬＢは光軸に平行に振動し、これ
により、非線形光学結晶４に入射するレーザ光ＬＢの入
射角は常にほぼ一定となる。因に、β−Ｂ４Ｂ２Ｏ４の
場合、位相整合条件を満足するための許容角度誤差は１
ｍｒａｄであるので上記のことは重要である。尚、図１
中の破線はレーザ光ＬＢをレンズ３の光軸に対して傾け
て入射した場合を示す。FIG. 1 is a diagram showing a harmonic generator according to a first embodiment of the present invention. A laser beam LB generated from the copper vapor laser 1 is shaped into a beam having a predetermined cross-sectional area by a beam expander (not shown) or the like, and then vibrated in a plane parallel to the drawing. Swung by. The oscillated laser light LB is condensed by the lens group 3 and is collected by the nonlinear optical crystal 4 (β in this embodiment).
-B4B2O4). At this time, if the center of vibration of the vibrating mirror 2 is arranged at the front focal point of the lens group 3, the laser beam LB vibrates parallel to the optical axis on the image side of the lens group 3, whereby the laser beam incident on the nonlinear optical crystal 4 The incident angle of the light LB is always substantially constant. In the case of β-B4B2O4, the allowable angle error for satisfying the phase matching condition is 1
This is important because it is mrad. FIG.
The broken line in the middle indicates the case where the laser beam LB is incident on the optical axis of the lens 3 at an angle.

【００２３】次に、本発明の第１の実施形態による高調
波発生装置を露光装置に適用したものを図３に基づいて
説明する。図１中の部材と同効のものには同一の符号を
付けてある。結晶４で発生した高調波光ＳＨはレンズ系
５で平行光に整形され、フライ・アイ・レンズ６に照射
される。フライ・アイ・レンズ６の各エレメントレンズ
からの高調波光はレンズ系７でレチクル・ブラインド８
上に重畳され、レンズ系９を介してダイクロイック・ミ
ラー１０に照射される。ダイクロイック・ミラー１０は
高調波光のみを反射し、その他の波長光は透過する。よ
って、高調波光のみがコンデンサ・レンズ１１を介して
レチクル１２を均一な照度分布で照射し、レチクルパタ
ーンが両側、又は片側テレセントリックな投影レンズ１
３によってウェハ１４上に投影、露光される。以上の構
成において、振動鏡２の振れ原点とフライ・アイ・レン
ズ６の入射面とはレンズ系３，５によって互いに共役で
あり、フライ・アイ・レンズ６の射出面（２次光源）と
投影レンズ１３の瞳（入射瞳）面（Ｅｐ）とは共役であ
る。さらに、レチクル・ブラインド８はレンズ系９、コ
ンデンサ・レンズ１１によってレチクル１２と共役にな
っている。また以上の構成において、結晶４中の集光点
からフライ・アイ・レンズ６までの距離をＲ、フライ・
アイ・レンズ６のレンズ素子の間隔をｄ、高調波の波長
をλとして、ｍ・（Ｒλ／ｄ）（ただし、ｍ＝１，２，
３，…）の範囲で、レーザ光ＬＢを結晶４中で揺動させ
ると、フライ・アイ・レンズ６の射出側にできる各エレ
メント・レンズ毎の２次光源からの光同士が干渉してレ
チクル上又はウェハ上に生じる不要な干渉縞が低減でき
る。この事は、一例として特開昭６３−１５９８３７号
公報（米国特許４，８５１，９７８号）に詳述してある
のでここでは説明は省略する。Next, an application of the harmonic generator according to the first embodiment of the present invention to an exposure apparatus will be described with reference to FIG. Components having the same effects as those in FIG. 1 are denoted by the same reference numerals. The harmonic light SH generated in the crystal 4 is shaped into parallel light by the lens system 5 and is irradiated on the fly-eye lens 6. Harmonic light from each element lens of the fly-eye lens 6 is converted into a reticle blind 8 by a lens system 7.
The light is superimposed on the light and illuminated on the dichroic mirror 10 via the lens system 9. The dichroic mirror 10 reflects only harmonic light and transmits other wavelength light. Therefore, only the harmonic light irradiates the reticle 12 with a uniform illuminance distribution via the condenser lens 11, and the reticle pattern has a bilateral or one-side telecentric projection lens 1
3 is projected and exposed on the wafer 14. In the above configuration, the deflection origin of the vibrating mirror 2 and the incident surface of the fly-eye lens 6 are conjugated to each other by the lens systems 3 and 5, and are projected to the exit surface (secondary light source) of the fly-eye lens 6. The pupil (entrance pupil) plane (Ep) of the lens 13 is conjugate. Further, the reticle blind 8 is conjugated with the reticle 12 by the lens system 9 and the condenser lens 11. In the above configuration, the distance from the focal point in the crystal 4 to the fly-eye lens 6 is R,
When the distance between the lens elements of the eye lens 6 is d and the wavelength of the harmonic is λ, m · (Rλ / d) (where m = 1, 2, 2,
When the laser beam LB is oscillated in the crystal 4 within the range of (3,...), The light from the secondary light sources of the respective element lenses formed on the emission side of the fly-eye lens 6 interfere with each other, and the reticle Unwanted interference fringes generated on the wafer or on the wafer can be reduced. This is described in detail in JP-A-63-159837 (U.S. Pat. No. 4,851,978) as an example, and the description is omitted here.

【００２４】図２は、本発明の第２の実施形態による高
調波発生装置を示す図である。この場合、第１の実施形
態による高調波発生装置の振動鏡２の代わりに傾斜可能
な平行平板ガラス１５を設ける。このとき、平行平板ガ
ラス１５より光源側にレンズ系３を設けることにより、
レーザ光ＬＢは結晶４内に集光され、かつ光軸と平行に
変位させることができる。このため、結晶４に入射する
レーザ光ＬＢの入射角は常にほぼ一定となり、位相整合
条件を満足する。FIG. 2 is a diagram showing a harmonic generator according to a second embodiment of the present invention. In this case, a tiltable parallel flat glass 15 is provided instead of the vibrating mirror 2 of the harmonic generator according to the first embodiment. At this time, by providing the lens system 3 on the light source side with respect to the parallel plate glass 15,
The laser beam LB is focused in the crystal 4 and can be displaced in parallel with the optical axis. Therefore, the incident angle of the laser beam LB incident on the crystal 4 is always substantially constant, and satisfies the phase matching condition.

【００２５】尚、本高調波発生装置を露光装置に適用す
る場合、結晶４以降の構成は図３と同様でよい。次に、
本発明における高調波発生装置の第３の実施形態を図４
に基づいて説明する。レーザ１から発生したレーザ光Ｌ
Ｂは、回動可能な平行平板ガラス１５に入射し、その
後、結晶４に達する。平行平板ガラス１５を回動させる
ことによってレーザ光ＬＢは光軸と平行な方向に揺動さ
せられる。この平行に揺動するレーザー光を非線形光学
結晶４に照射して高調波光を発生させる。この高調波発
生装置を露光装置に適用したものを図５に示す。結晶４
で発生した高調波光ＳＨは、一旦レンズ系１７で集光さ
れ再度レンズ系５で所定の断面積を持ったほぼ平行なビ
ームに整形され、光軸に平行に振動しながらフライ・ア
イ・レンズ６に入射する。このとき、レンズ系１７の像
側焦点とレンズ系５の前側焦点はほぼ一致している。フ
ライ・アイ・レンズ６で生じた２次光源からの光は、そ
のままレンズ系７へ入射したのではレチクル・ブライン
ド８上に静止した干渉縞が生じるので、レンズ系７とレ
チクル・ブラインド８との間に振動鏡１８を設ける。こ
の場合、振動鏡１８の振動範囲は例えば干渉縞のピッチ
の整数倍（１倍も含む）の移動に対応するものとし、所
望の露光量を得るために必要な複数パルスで１／２周期
振動するものとする。When the present harmonic generator is applied to an exposure apparatus, the structure after the crystal 4 may be the same as that shown in FIG. next,
FIG. 4 shows a third embodiment of the harmonic generator according to the present invention.
It will be described based on. Laser light L generated from laser 1
B enters the rotatable parallel flat glass 15 and thereafter reaches the crystal 4. By rotating the parallel plate glass 15, the laser beam LB is swung in a direction parallel to the optical axis. The non-linear optical crystal 4 is irradiated with the laser light oscillating in parallel to generate harmonic light. FIG. 5 shows an application of this harmonic generator to an exposure apparatus. Crystal 4
Is generated by the lens system 17, is once again condensed by the lens system 5 into a substantially parallel beam having a predetermined cross-sectional area, and vibrates parallel to the optical axis while the fly-eye lens 6 is being vibrated. Incident on. At this time, the image-side focal point of the lens system 17 and the front-side focal point of the lens system 5 substantially match. If the light from the secondary light source generated by the fly-eye lens 6 enters the lens system 7 as it is, a stationary interference fringe is formed on the reticle blind 8. A vibrating mirror 18 is provided therebetween. In this case, the vibration range of the vibrating mirror 18 corresponds to, for example, a movement of an integral multiple (including one) of the pitch of the interference fringes, and a half-period vibration with a plurality of pulses necessary to obtain a desired exposure amount. It shall be.

【００２６】図６は、本発明の第４の実施形態による高
調波発生装置を示す図である。銅蒸気レーザ１から発生
したレーザ光ＬＢは、不図示のビームエキスパンダ等に
より所定の断面積を持ったビームに整形され、反射鏡等
で振動することなくレンズ群３で集光して非線形光学結
晶４へ照射される。又、結晶４中の温度分布が急峻にな
るのを避けるため、結晶４に振動器１５を設け、結晶４
を光軸とほぼ垂直な方向に振動させて結晶４を通るレー
ザ光ＬＢの通過領域を逐次変化させるようにする。FIG. 6 is a diagram showing a harmonic generator according to a fourth embodiment of the present invention. The laser beam LB generated from the copper vapor laser 1 is shaped into a beam having a predetermined cross-sectional area by a beam expander (not shown) or the like, and is condensed by the lens group 3 without being vibrated by a reflecting mirror or the like, and is then subjected to nonlinear optics. The crystal 4 is irradiated. Further, in order to prevent the temperature distribution in the crystal 4 from becoming steep, a vibrator 15 is provided in the crystal 4,
Is vibrated in a direction substantially perpendicular to the optical axis so that the passage area of the laser beam LB passing through the crystal 4 is sequentially changed.

【００２７】この図６の高調波発生装置を露光装置に適
用する場合、フライ・アイ・レンズ６以降の構成は図５
と同様であるが、非線形光学結晶４とフライ・アイ・レ
ンズ６との間に、高調波ＳＨをフライ・アイ・レンズ６
に平行に入射させるための不図示のレンズ系を設ける。
図７は、本発明の第５の実施形態による高調波発生装置
の構成を示す図である。レーザ光源１から発生したレー
ザ光ＬＢは、不図示のビームエキスパンダ等により所定
の断面積を持った平行ビームに整形されるか、又はレー
ザ光源１から射出したままの状態で、揺動させられるこ
となく非線形光学結晶４に照射され、結晶４によってほ
ぼ平行な高調波光束に変換される。結晶４は図６と同様
に振動器１６によりレーザ光の光軸とほぼ垂直な方向に
振動して、結晶４中の温度分布が急峻になるのを防ぐ、
このとき、結晶４の位相整合条件を満足するように、即
ち、レーザ光の結晶４への入射角の変動範囲が１ｍｒａ
ｄ以内になるようにしなければならない。この高調波発
生装置を露光装置に適用する場合、フライ・アイ・レン
ズ６以降の構成は図５と同様である。When the harmonic generator shown in FIG. 6 is applied to an exposure apparatus, the structure after the fly-eye lens 6 is shown in FIG.
Except that a harmonic SH is introduced between the nonlinear optical crystal 4 and the fly-eye lens 6.
Is provided with a lens system (not shown) for causing the light to enter in parallel.
FIG. 7 is a diagram showing a configuration of a harmonic generation device according to a fifth embodiment of the present invention. The laser light LB generated from the laser light source 1 is shaped into a parallel beam having a predetermined cross-sectional area by a beam expander or the like (not shown), or is swung while being emitted from the laser light source 1. Irradiated to the nonlinear optical crystal 4 without being converted by the crystal 4 into a substantially parallel harmonic light beam. The crystal 4 is vibrated by the vibrator 16 in a direction substantially perpendicular to the optical axis of the laser beam as in FIG. 6 to prevent the temperature distribution in the crystal 4 from becoming sharp.
At this time, the variation range of the incident angle of the laser beam to the crystal 4 is set to 1 mra so as to satisfy the phase matching condition of the crystal 4.
d. When this harmonic generator is applied to an exposure apparatus, the configuration after the fly-eye lens 6 is the same as that in FIG.

【００２８】以上、いずれの実施例においても、振動鏡
２、平行平板ガラス１５、又は振動器１６の駆動は、レ
ーザ光源１がパルス発光するものであれば、そのパルス
発光（トリガ）と同期させて、各パルス毎に微小角度あ
るいは微少量だけ駆動して、非線形光学結晶中のレーザ
光通過位置を時間的に一様に変化させるように制御する
ことが望ましい。As described above, in any of the embodiments, the driving of the vibrating mirror 2, the parallel plate glass 15, or the vibrator 16 is synchronized with the pulse light emission (trigger) if the laser light source 1 emits pulse light. Then, it is desirable to control the laser beam passing position in the nonlinear optical crystal to change uniformly with time by driving a small angle or a small amount for each pulse.

【００２９】[0029]

【発明の効果】以上のように本願の各請求項に記載の発
明によれば、レーザ光ＬＢの光路を変位させて高調波発
生手段（結晶４）への照射位置を変更しているので、非
線形光学結晶の寿命を延ばすことができる。また、高調
波発生手段（結晶）へのレーザ光の入射角をほぼ一定に
維持した状態でレーザ光の光路を変位させれば、位相整
合条件を満足して、高調波の発生効率をほぼ一定に保つ
ことができる（高調波の発生効率の低下を招かない）。
また更に、結晶４の直前に配置された光学部材（例えば
図１、３のレンズ３）へのレーザ光の照射位置も変位す
ることとなるので、光学部材の寿命も延ばすことができ
る。更に請求項８，９，２１に記載のように、この種の
高調波発生装置（高調波発生方法）を露光装置（露光方
法）に使用した場合、レーザ光を結晶に対して揺動させ
るようにすれば、高調波光の空間的、時間的コヒーレン
スの向上に起因してマスク（レチクル１２）又は基板
（ウェハ１４）上に生じる不要な干渉パターンを低減
（平滑化）することができる。As described above, the invention described in each claim of the present application is described.
According to Ming, the optical path of the laser beam LB is displaced to generate harmonics.
Since the irradiation position on the raw means (crystal 4) has been changed,
The life of the linear optical crystal can be extended. Also, harmonic
Make the incident angle of laser light on the wave generation means (crystal) almost constant
If the optical path of the laser beam is displaced while maintaining the
Satisfies the mixing conditions and keeps the harmonic generation efficiency almost constant
(Without lowering the generation efficiency of harmonics).
Furthermore, since the irradiation position of the laser beam on the optical member which is arranged immediately before the crystals 4 (for example, a lens 3 of FIG. 1, 3) so that the displacement can be extended also the life of the optical member. Further, as described in claim 8, 9, 21, when using this type of harmonic generator (harmonic generation process) in the exposure apparatus (exposure method), so as to swing the laser beam to the crystal Accordingly, unnecessary interference patterns generated on the mask (reticle 12) or the substrate (wafer 14) due to the improvement of the spatial and temporal coherence of the harmonic light can be reduced (smoothed).

【００３０】また請求項１、８、１６に記載の発明によ
れば、振動鏡２の振動中心をレンズ３の前側焦点に配置
したので、高調波発生手段（非線形光学結晶４）に入射
するレーザ光の入射角を常にほぼ一定にすることがで
き、このため位相整合条件が満足され高調波の発生効率
の低減を防止できる。また請求項２、９，１７に記載の
発明によれば、レーザ光源１と平行平板ガラス１５との
間に、レーザ光を集光するレンズ３を設けたので、レー
ザ光を高調波発生手段（非線形光学結晶４）内に集光で
き且つ光軸と平行に変位でき、このため結晶４に入射す
るレーザ光の入射角を常にほぼ一定にでき、位相整合条
件を満足でき高調波の発生効率の低減を防止できる。According to the first, eighth and sixteenth aspects of the present invention, the center of vibration of the vibrating mirror 2 is arranged at the front focal point of the lens 3, so that the laser beam incident on the harmonic generating means (nonlinear optical crystal 4). The incident angle of light can always be made substantially constant, so that the phase matching condition is satisfied and the reduction of the generation efficiency of harmonics can be prevented. According to the invention described in claim 2,9,17, between the laser light source 1 and the flat row plate glass 15, since the laser beam is provided a lens 3 for condensing light, harmonic generation unit of the laser beam (Non-linear optical crystal 4) can be condensed and displaced parallel to the optical axis, so that the incident angle of the laser beam incident on the crystal 4 can always be almost constant, and the phase matching condition can be satisfied, and the generation efficiency of harmonics Reduction can be prevented.

[Brief description of the drawings]

【図１】図１は本発明の第１の実施形態による高調波発
生装置を示す図である。FIG. 1 is a diagram showing a harmonic generation device according to a first embodiment of the present invention.

【図２】図２は本発明の第２の実施形態による高調波発
生装置を示す図である。FIG. 2 is a diagram showing a harmonic generation device according to a second embodiment of the present invention.

【図３】図３は本発明の第１の実施形態による高調波発
生装置を適用した露光装置の構成を示す図である。FIG. 3 is a diagram showing a configuration of an exposure apparatus to which the harmonic generator according to the first embodiment of the present invention is applied.

【図４】図４は本発明の第３の実施形態による高調波発
生装置を示す図である。FIG. 4 is a diagram showing a harmonic generator according to a third embodiment of the present invention.

【図５】図５は本発明の第３の実施形態による高調波発
生装置を適用した露光装置の構成を示す図である。FIG. 5 is a diagram showing a configuration of an exposure apparatus to which a harmonic generator according to a third embodiment of the present invention is applied.

【図６】図６は本発明の第４の実施形態による高調波発
生装置を示す図である。FIG. 6 is a diagram showing a harmonic generation device according to a fourth embodiment of the present invention.

【図７】図７は本発明の第５の実施形態による高調波発
生装置を示す図である。FIG. 7 is a diagram showing a harmonic generation device according to a fifth embodiment of the present invention.

[Explanation of Signs of Main Parts]

１金属蒸気レーザ２，１８振動鏡３，５，７，９，１７レンズ群４非線形光学結晶６フライ・アイ・レンズ１５平行平板ガラス１６振動器 DESCRIPTION OF SYMBOLS 1 Metal vapor laser 2,18 Vibration mirror 3,5,7,9,17 Lens group 4 Nonlinear optical crystal 6 Fly-eye lens 15 Parallel plate glass 16 Vibrator

フロントページの続き (58)調査した分野(Int.Cl.⁷，ＤＢ名) H01L 21/027 G03F 7/20 H01S 3/109 H01S 3/227 Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/20 H01S 3/109 H01S 3/227

Claims

(57) [Claims]

A laser light source for generating a laser light ; a harmonic generation means for generating a harmonic light of the laser light by irradiating the laser light; and a laser light source and the harmonic generation means. It is placed between, substantially perpendicular towards relative optical path an optical path of the laser beam
A vibrating mirror as an optical path displacing means for displacing the vibrating mirror in a direction, and disposed between the vibrating mirror and the harmonic generating means;
The laser light reflected by the vibrating mirror is condensed to generate the higher harmonic wave.
A lens for irradiating the raw means , wherein a vibration center of the vibrating mirror is disposed at a front focal point of the lens.
An apparatus for generating harmonics of laser light, comprising:

2. A laser light source for generating laser light, a harmonic generating means for generating harmonic light of the laser light by irradiating the laser light , and a laser light source and the harmonic generating means. Placed between
And can be tilted with respect to the optical axis of the laser light.
Due to the inclination, the optical path of the laser light is almost perpendicular to the optical path.
Parallel plate glass as optical path displacement means for displacing in various directions
Disposed between the laser light source and the parallel plate glass.
And a lens for condensing the laser light.
Characteristic harmonic generator of laser light .

3. The parallel plate glass is provided with a laser beam.
3. The apparatus according to claim 2, wherein the apparatus is rotatable about an optical axis.
2. The harmonic generator according to item 1 .

4. The optical path changing means according to claim 1 , wherein
The road is linearly displaced.
The harmonic generation device according to any one of the above .

5. The optical path displacing means, wherein the harmonic generating means is
The passing position of the laser light in the step is changed uniformly over time.
The method according to any one of claims 1 to 4, wherein
Harmonic generator .

6. A laser light source for emitting a pulse light.
It includes a pulse light source, the optical path displacement means, pulse light emitted from the pulsed light source
Displace the optical path of the laser light in synchronization with the cycle
The height according to any one of claims 1 to 5, characterized in that:
Harmonic generator .

7. The optical path displacing means, wherein the harmonic generating means is
The incident angle of the laser light incident on the stage is maintained substantially constant.
Characterized in that the optical path of the laser light is displaced in the state of
The harmonic generator according to any one of claims 1 to 6.
Place .

8. A laser light source for generating laser light, and said laser light source.
The laser beam is irradiated to generate a harmonic light of the laser beam.
And a harmonic generation means for generating a harmonic of the laser light.
By irradiating the mask with light, the pattern on the mask is
An exposure apparatus for exposing a laser beam onto a substrate , wherein the exposure apparatus is disposed between the laser light source and the harmonic generation means.
The optical path of the laser light is substantially perpendicular to the optical path.
A vibrating mirror as an optical path displacing means for displacing in the direction, disposed between the vibrating mirror and the harmonic generating means,
The laser light reflected by the vibrating mirror is condensed to generate the higher harmonic wave.
A lens for irradiating the raw means , wherein a vibration center of the vibrating mirror is disposed at a front focal point of the lens.
An exposure apparatus, comprising:

9. A laser light source for generating laser light, and said laser light source.
The laser beam is irradiated to generate a harmonic light of the laser beam.
And a harmonic generation means for generating a harmonic of the laser light.
By irradiating the mask with light, the pattern on the mask is
An exposure apparatus for exposing a laser beam onto a substrate , wherein the exposure apparatus is disposed between the laser light source and the harmonic generation means.
And can be tilted with respect to the optical axis of the laser light.
Due to the inclination, the optical path of the laser light is almost perpendicular to the optical path.
Parallel plate glass as optical path displacement means for displacing in various directions
Disposed between the laser light source and the parallel plate glass.
And a lens for condensing the laser light.
Exposure equipment characterized .

10. The parallel plate glass, wherein the laser light
Claims: It is rotatable with respect to the optical axis of
10. The exposure apparatus according to 9 .

11. The optical path displacement means according to claim 1 , wherein
The optical path is linearly displaced.
The exposure apparatus according to claim 10 .

12. The optical path shifting means according to claim 11 , wherein
Temporally evenly changing passage position of the lasers light in means
The method according to any one of claims 8 to 11, wherein
Exposure apparatus according to the above .

13. The laser light source emits pulsed light.
A pulsed light source , wherein the optical path displacement unit is configured to emit a pulsed light from the pulsed light source.
Displace the optical path of the laser light in synchronization with the cycle
The method according to any one of claims 8 to 12, wherein
Exposure equipment .

14. The optical path shifting means according to claim 1 , wherein
The incident angle of the laser beam incident on the means is kept almost constant
In this state, the optical path of the laser light is displaced.
The exposure apparatus according to any one of claims 8 to 13, wherein
Place .

15. The method according to claim 1, wherein the mask is uniformly irradiated with the laser light.
The apparatus further includes an illuminance distribution uniformizing unit for illuminating with the illuminance, and a variation range of the laser beam passage area by the optical path displacement unit.
The area is the focal point of the laser light in the harmonic generation means.
The distance from the illuminance uniforming means to the illuminance uniforming means is R,
The distance between the optical elements of the means is d, the wavelength of the harmonic is λ,
m · (Rλ / d) (where m = 1, 2, 3, ...)
Before passing through the illuminance distribution equalizing means.
The variation range of the laser light is adjusted by the illuminance distribution uniformizing means.
2mπ between light from adjacent secondary light sources
9. A range in which a phase difference of?
The exposure apparatus according to any one of claims 14 to 14 .

16. A laser light generated from a laser light source
Irradiates the harmonic generation means to generate harmonics of the laser light
A that method, is arranged between the laser light source said harmonic generation unit
The optical path of the laser light with respect to the optical path
And displaces it in a substantially vertical direction, and a laser disposed between the vibrating mirror and the harmonic generation means.
The center of vibration at the front focal point of the lens.
Condensing the laser light reflected by the vibrating mirror,
Irradiating the harmonic generation means with laser light
Harmonic generation method .

17. A laser beam generated from a laser light source
Irradiates the harmonic generation means to generate harmonics of the laser light
Method , wherein the laser light source is disposed between the laser light source and the harmonic generation means.
Parallel plate that is tiltable with respect to the optical axis of the laser light
The glass causes the optical path of the laser light to be approximately
Displaced in a substantially vertical direction , disposed between the laser light source and the parallel flat glass.
The laser beam is condensed by the converging lens
Laser beam harmonics characterized by irradiating flat glass
How it occurs .

18. An optical path of the laser beam, wherein the harmonic path is
The passing position of the laser light in the generating means changes uniformly over time.
17. The method according to claim 16, wherein
18. The method for generating harmonics of laser light according to item 17 .

19. The laser light source emits pulsed light.
A pulsed light source , wherein an optical path of the laser light includes a pulsed light from the pulsed light source.
2. The displacement according to claim 1, wherein the displacement is synchronized with an optical cycle.
19. A method for generating harmonics of a laser beam according to any one of 6 to 18.
Law .

20. An optical path of the laser light, wherein the harmonics
The incident angle of the laser beam incident on the generating means is kept substantially constant.
17. Displaced while being held.
20. A method for generating harmonics of a laser beam according to any one of items 19 to 19.
Law .

21. The method according to any one of claims 16 to 20.
The laser beam generated by the method for generating harmonics of laser light
By irradiating the mask with the harmonic light of the light,
Exposure to expose the pattern formed on the mask onto the substrate
Light method .

22. The illuminance distribution uniformizing means,
The laser beam having a uniform illuminance is illuminated, and the variation range of the laser beam passage area is determined by the harmonic generation means.
From the focal point of the laser light in the stage to the illuminance uniforming means.
Where R is the distance between the optical elements of the illuminance uniformizing means.
d, where λ is the wavelength of the harmonic, and m · (Rλ / d) (where
m = 1, 2, 3,...)
Fluctuation range of the laser light passing through the degree distribution uniformizing means
Adjacent to each other formed by the illuminance distribution uniformizing means.
Range that gives a phase difference of 2mπ between the lights from the secondary light sources
22. The exposure method according to claim 21, wherein:

23. An exposure method according to claim 21.
A device manufacturing method using the method .