JPH0749926B2 - Alignment method and alignment device - Google Patents
Alignment method and alignment deviceInfo
- Publication number
- JPH0749926B2 JPH0749926B2 JP61104186A JP10418686A JPH0749926B2 JP H0749926 B2 JPH0749926 B2 JP H0749926B2 JP 61104186 A JP61104186 A JP 61104186A JP 10418686 A JP10418686 A JP 10418686A JP H0749926 B2 JPH0749926 B2 JP H0749926B2
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- light
- diffraction
- incident
- diffracted light
- 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.)
- Expired - Fee Related
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7049—Technique, e.g. interferometric
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
- G03F9/7023—Aligning or positioning in direction perpendicular to substrate surface
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
- Length Measuring Devices By Optical Means (AREA)
- Optical Transform (AREA)
- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、半導体ICやLSIを製造するための露光装置や
パタン評価装置等に応用して好適な位置合わせ方法およ
びその実施に使用される位置合わせ装置に関するもので
ある。DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applied to an exposure apparatus for manufacturing a semiconductor IC or LSI, a pattern evaluation apparatus, and the like, and is used for a suitable alignment method and its implementation. The present invention relates to a positioning device.
半導体ICやLSIの微細化に伴い、マスクパタンをウエハ
に一括して、もしくはステップ・アンド・レピート方式
によって露光転写する装置では、マスクとウエハとを互
いに高精度に位置合わせする技術の進展が不可欠のもの
となっている。With the miniaturization of semiconductor ICs and LSIs, it is essential to advance the technology for aligning the mask and the wafer with high precision in an apparatus that transfers the mask pattern to the wafer all at once or by the step-and-repeat method. It has become.
従来、光ヘテロダイン干渉を利用して微小変位測定ある
いは精密な位置合わせを行なう装置として、第4図に示
すような2つの回折格子の回折光を用いるものがある
(特願昭60−198966号)。第4図において、13は周波数
が互いにわずかに異なり、偏光面方向が互いに直交する
2波長の光を発する2波長直交偏光レーザー光源、1
は、ビームスプリッター、2,2′は集光レンズ、3,3′,
3″,3はミラー、4は偏光ビームスプリッター、5,5′
は光検出器、6は信号処理制御部、7はマスクステー
ジ、8はマスク(第1の物体)、9は透過型回折格子
(第1の回折格子)、10は反射型回折格子(第2の回折
格子)、11はウエハ(第2の物体)、12はウエハステー
ジである。2. Description of the Related Art Conventionally, there is an apparatus that uses diffracted light from two diffraction gratings as shown in FIG. 4 as a device for performing minute displacement measurement or precise alignment using optical heterodyne interference (Japanese Patent Application No. 60-198966). . In FIG. 4, 13 is a two-wavelength orthogonal polarization laser light source which emits two wavelengths whose frequencies are slightly different from each other and whose polarization plane directions are orthogonal to each other.
Is a beam splitter, 2,2 'is a condenser lens, 3,3',
3 ″, 3 is a mirror, 4 is a polarization beam splitter, and 5,5 ′
Is a photodetector, 6 is a signal processing controller, 7 is a mask stage, 8 is a mask (first object), 9 is a transmissive diffraction grating (first diffraction grating), and 10 is a reflective diffraction grating (second diffraction grating). Diffraction grating), 11 is a wafer (second object), and 12 is a wafer stage.
第4図において、2波長直交偏光レーザー光源13から発
した光の一部を、ビームスプリッター1を介して取り出
し、集光レンズ2を通して光検出器5で検出し、基準ビ
ート信号として信号処理制御部6に入力する。一方、2
波長直交偏光レーザー光源13から発した光は、ビームス
プリッター1、ミラー3を介して偏光ビームスプリッタ
ー4に入る。偏光ビームスプリッター4により、それぞ
れ水平成分、あるいは垂直成分のみを有する直線偏光で
しかも周波数がわずかに異なる2波長の光に分割され、
それぞれ、ミラー3′,3″を介して所望の入射角で透過
型回折格子9、および反射型回折格子10に入射する。回
折格子9,10から得られた回折光をミラー3、集光レン
ズ2′を介して光検出器5′により検出し、回折光ビー
ト信号として信号処理制御部6に入力する。信号処理制
御部6では、基準ビート信号と回折光ビート信号との位
相差を検出し、位相差が0゜になるように保持移動機構
(図示略)を制御してマスクステージ7、およびウエハ
ステージ12を相対移動させ、マスク面上のパタンがウエ
ハ面上の所定の位置に精度よく重なって露光できるよう
にマスク8とウエハ11との間の精密な位置合わせを行な
う。In FIG. 4, a part of the light emitted from the two-wavelength orthogonal polarization laser light source 13 is taken out through the beam splitter 1, detected by the photodetector 5 through the condensing lens 2, and a signal processing controller as a reference beat signal. Enter in 6. On the other hand, 2
The light emitted from the wavelength orthogonal polarization laser light source 13 enters the polarization beam splitter 4 via the beam splitter 1 and the mirror 3. The polarization beam splitter 4 splits the light into two linearly polarized lights each having only a horizontal component or a vertical component and having slightly different frequencies,
The light enters the transmission diffraction grating 9 and the reflection diffraction grating 10 at desired incident angles via the mirrors 3'and 3 ", respectively. The diffracted light obtained from the diffraction gratings 9 and 10 is reflected by the mirror 3 and the condenser lens. The light is detected by the photodetector 5'through 2 ', and is input as a diffracted light beat signal to the signal processing control unit 6. The signal processing control unit 6 detects the phase difference between the reference beat signal and the diffracted light beat signal. , The holding / moving mechanism (not shown) is controlled so that the phase difference becomes 0 °, and the mask stage 7 and the wafer stage 12 are moved relative to each other, and the pattern on the mask surface is accurately positioned at a predetermined position on the wafer surface. Precise alignment between the mask 8 and the wafer 11 is performed so that they can be overlapped and exposed.
次に、このように構成された位置合わせ装置を用いる位
置合わせ方法を第5図を参照して説明する。第5図にお
いて、14は透過型回折格子、15は反射型回折格子、16,1
7は周波数が互いにわずかに異なる2波長の入射光、18,
19は所望の回折光、16−1,17−1は透過型回折格子14か
らの−1次透過回路光、16−1′,17−1′は反射型回
折格子15からの1次反射回折光、16−2,17−2は、反射
型回折格子15からの−1次透過回折光である。P1,P2は
それぞれ透過型回折格子14、反射型回折格子15の格子ピ
ッチである。なお、一般に、格子ピッチPの回折格子に
波長λの光を入射させた場合、回折光はθ=sin-1(m
・2/P)(m=0,±1,±2,…)の方向でのみ強くなり、
mの値によって、m次の回折光と呼ばれている。Next, a positioning method using the positioning device thus configured will be described with reference to FIG. In FIG. 5, 14 is a transmission type diffraction grating, 15 is a reflection type diffraction grating, and 16 and 1.
7 is two wavelengths of incident light whose frequencies are slightly different from each other, 18,
19 is the desired diffracted light, 16-1 and 17-1 are the -1st order transmission circuit light from the transmission type diffraction grating 14, 16-1 'and 17-1' are the 1st order reflection diffraction from the reflection type diffraction grating 15. Lights 16-2 and 17-2 are the −1st order transmitted diffracted light from the reflection type diffraction grating 15. P 1 and P 2 are the grating pitches of the transmission type diffraction grating 14 and the reflection type diffraction grating 15, respectively. Generally, when light of wavelength λ is incident on a diffraction grating having a grating pitch P, the diffracted light is θ = sin −1 (m
・ It becomes strong only in the direction of 2 / P) (m = 0, ± 1, ± 2,…),
Depending on the value of m, it is called m-th order diffracted light.
入射光16,17の入射方向を回折格子面に鉛直な方向に対
し、回折格子14および15のそれぞれの±1次反射回折光
の角度をそれぞれψ-1=sin-1(−λ1/P1)、ψ+1=sin
-1(λ2/P1)、θ-1=sin-1(−λ1/P2)、θ+1=sin-1
(λ2/P2)とした時、(ψ-1+θ-1)および(ψ+1+θ
+1)の角度に設定する。ここで、入射光16,17の波長は
λ1,λ2であり、周波数差Δfは、数KHzから数百MHz程
度の値であり、光速Cに比べて非常に小さく、2波長λ
1,λ2に対する±1次回折角はほぼ等しくなる。したが
って、ψ-1≒ψ+1,θ-1≒θ+1となり、(ψ-1+θ-1)
≒(ψ+1+θ+1)となる。The angles of the ± 1st-order reflected diffracted lights of the diffraction gratings 14 and 15 are ψ −1 = sin −1 (−λ 1 / P, respectively) with respect to the direction in which the incident lights 16 and 17 are perpendicular to the diffraction grating surface. 1 ), ψ +1 = sin
-1 (λ 2 / P 1 ), θ -1 = sin -1 (-λ 1 / P 2 ), θ +1 = sin -1
When (λ 2 / P 2 ), (ψ -1 + θ -1 ) and (ψ +1 + θ)
+1 ) angle. Here, the wavelengths of the incident lights 16 and 17 are λ 1 and λ 2 , and the frequency difference Δf is a value of about several KHz to several hundreds MHz, which is very small compared to the speed of light C and two wavelengths λ.
The ± first-order diffraction angles for 1 and λ 2 are almost equal. Therefore, ψ −1 ≈ ψ +1 and θ −1 ≈ θ +1 and (ψ -1 + θ -1 )
≈ (ψ +1 + θ +1 ).
こうすることにより、回折格子14,15に入射した入射光1
6,17は、それぞれ透過型回折格子14で回折されて−1次
透過回折光16−1,17−1となり、入射角θ-1,θ+1でそ
れぞれ反射型回折格子15に入射し、ここでそれぞれ反射
回折されて−1次反射回折光16−1′,17−1′とな
る。−1次反射回折光16−1′,17−1′は、回折格子
の鉛直方向にそれぞれ回折された回折光であり、光学的
に合成され透過型回折格子14によって0次透過回折され
て所望の回折光18となる。一方、回折格子14,15に入射
した入射光16,17の一部は、透過型回折格子14によって
0次透過回折されて反射型回折格子15に入射し、ここで
反射回折されて−1次反射回折光16−2,17−2となり、
透過型回折格子14に入射角ψ-1,ψ+1でそれぞれ入射す
る。−1次反射回折光16−2,17−2は、透過型回折格子
14で透過回折されてそれぞれ回折格子14に対して鉛直方
向の−1次透過回折光として光合成されて所望の回折光
19となる。そして、前記光検出器5′により、所望の回
折光18,19から光ヘテロダイン干渉によるビート信号を
検出し、基準信号との位相差を測定してマスク8とウエ
ハ11との位置合わせを行なう。By doing so, the incident light 1 incident on the diffraction gratings 14 and 15
6, 17 are respectively diffracted by the transmission type diffraction grating 14 to become −1st order transmission diffracted light 16-1, 17-1, which respectively enter the reflection type diffraction grating 15 at incident angles θ −1 , θ +1 . Here, they are respectively reflected and diffracted to become -1st-order reflected diffracted lights 16-1 'and 17-1'. The -1st-order reflected diffracted lights 16-1 'and 17-1' are diffracted lights that are diffracted in the vertical direction of the diffraction grating, and are optically synthesized and are zero-order transmitted and diffracted by the transmission type diffraction grating 14 to be desired. Diffracted light 18 becomes. On the other hand, a part of the incident light 16 and 17 that has entered the diffraction gratings 14 and 15 is 0-order transmission diffracted by the transmission diffraction grating 14 and enters the reflection diffraction grating 15, where it is reflected and diffracted to the -1st order. It becomes reflected diffracted light 16-2, 17-2,
The light enters the transmission diffraction grating 14 at incident angles ψ −1 and ψ +1 respectively. -1st order reflected diffracted light 16-2, 17-2 is a transmission type diffraction grating
The light is transmitted and diffracted by 14 and is combined with each other as the -1st-order transmitted diffracted light in the vertical direction with respect to the diffraction grating 14, and the desired diffracted light
It will be 19. Then, the photodetector 5'detects the beat signal due to the optical heterodyne interference from the desired diffracted lights 18 and 19, and the phase difference with the reference signal is measured to align the mask 8 and the wafer 11.
ところで上記従来の方法では、前記マスク8および前記
ウエハ11の位置合わせ点をマスク8およびウエハ11の座
標原点とし、座標原点に対するマスク8およびウエハ11
の微小変位をそれぞれΔM,ΔWとしたとき、基準信号と
ビート信号との位相差ΔφとΔM,ΔWとの間には、 の関係があり、したがってΔM,ΔWのそれぞれ独立した
微小変位に対して位相差Δφを生じ、ΔM=ΔW=0の
ときにΔφ=0となり位置合わせ点となる。したがって
位置合わせを行なう場合、あらかじめΔMあるいはΔW
のいずれか一方の座標原点位置すなわち変位量0に設定
し、その後他方をその座標原点に位置合わせ制御すると
いう手順が必要である。そして、ΔMあるいはΔWのい
ずれか一方の変位量をあらかじめ座標原点に設定するた
めには、回折格子9あるいは回折格子10のいずれか一方
だけを用いたヘテロダイン干渉によりビート信号を検出
し、そのビート信号と基準信号との位相差が0゜となる
ように設定しなければならない。By the way, in the above-mentioned conventional method, the alignment point of the mask 8 and the wafer 11 is set as the coordinate origin of the mask 8 and the wafer 11, and the mask 8 and the wafer 11 with respect to the coordinate origin.
Where ΔM and ΔW are the small displacements of, respectively, between the phase difference Δφ between the reference signal and the beat signal and ΔM and ΔW, Therefore, a phase difference Δφ is generated for each minute displacement of ΔM and ΔW, and Δφ = 0 when ΔM = ΔW = 0, which is the alignment point. Therefore, when performing alignment, ΔM or ΔW must be set in advance.
It is necessary to set one of the coordinate origin positions, that is, the displacement amount to 0, and then perform the alignment control of the other coordinate origin position. Then, in order to set the displacement amount of either ΔM or ΔW in advance to the coordinate origin, the beat signal is detected by the heterodyne interference using only one of the diffraction grating 9 and the diffraction grating 10, and the beat signal is detected. Must be set so that the phase difference between the reference signal and the reference signal is 0 °.
ところが、その設定は1重回折によって行われるので、
その後の位置合わせの際の2重回折の場合とは入射角度
が異なり、したがってそのための独立した光学系が必要
であるという欠点がある。However, since the setting is performed by single diffraction,
The incident angle is different from the case of double diffraction in the subsequent alignment, and therefore there is a drawback that an independent optical system for that is required.
また、この方法では、マスク8とウエハ11との相対的位
置ずれ量が0の場合であっても、マスク8とウエハ11が
同一方向に同一量だけ動いた場合には位相差Δφが生じ
る。すなわち、マスク8とウエハ11が双方とも座標原点
位置のときのみΔφ=0となるので、マスク8とウエハ
11との相対的位置合わせを行なう方法としては適用しに
くいものであった。Further, in this method, even when the relative positional displacement amount between the mask 8 and the wafer 11 is 0, when the mask 8 and the wafer 11 move in the same direction by the same amount, a phase difference Δφ occurs. That is, Δφ = 0 only when both the mask 8 and the wafer 11 are at the coordinate origin position.
It was difficult to apply as a method to perform relative alignment with 11.
さらにこの方法では、2つの回折格子によって2重に回
折された回折光を検出するので、得られる回折光の強度
が微弱であるという欠点もある。Further, in this method, since the diffracted light diffracted doubly by the two diffraction gratings is detected, the intensity of the obtained diffracted light is weak.
本発明は上記の事情に鑑みてなされたもので、その目的
とするところは、2物体の相対的変位量を直接的に位相
差信号として取り出すことにより、2物体の絶対座標に
よる位相関係には無関係に、高精度の位置合わせを行う
ことのできる方法、およびそのための位置合わせ装置を
提供することにある。The present invention has been made in view of the above circumstances. An object of the present invention is to directly extract the relative displacement amount of two objects as a phase difference signal to obtain a phase relationship based on absolute coordinates of the two objects. An object of the present invention is to provide a method capable of performing highly accurate alignment independently of the above, and an alignment device therefor.
第1の発明の位置合わせ方法は、第1の物体に設けた第
1の回折格子と第2の物体に設けた第2の回折格子のそ
れぞれに対して、周波数が互いにわずかに異なる2波長
の単色光を入射し、前記第1の回折格子から生じる光ヘ
テロダイン干渉回折光を検出して第1のビート信号を生
成するとともに、前記第2の回折格子から生じる光ヘテ
ロダイン干渉回折光を検出して第2のビート信号を生成
し、それら第1および第2のビート信号の位相差を測定
することによって、前記第1および第2の物体の回折格
子の回折格子ラインに直角の回折格子ピッチ方向の相対
変位量を検出することを特徴としている。According to the alignment method of the first invention, two wavelengths whose frequencies are slightly different from each other are respectively applied to the first diffraction grating provided on the first object and the second diffraction grating provided on the second object. Injecting monochromatic light, detecting optical heterodyne interference diffracted light generated from the first diffraction grating to generate a first beat signal, and detecting optical heterodyne interference diffracted light generated from the second diffraction grating. By generating a second beat signal and measuring the phase difference between the first and second beat signals, a diffraction grating pitch direction perpendicular to the diffraction grating lines of the diffraction gratings of the first and second objects is obtained. The feature is that the relative displacement amount is detected.
また、第2の発明の位置合わせ装置は、第1の物体に設
けた第1の回折格子と、第2の物体に設けた第2の回折
格子と、前記第1および第2の物体を相対的に動かす移
動機構と、周波数が互いにわずかに異なる2波長の単色
光を発生する光源と、前記光源から発生した2波長の単
色光を前記第1および第2の回折格子のそれぞれに対し
て所定の入射角度で入射させる入射角調整手段と、前記
第1の回折格子から生じる光ヘテロダイン干渉回折光を
検出して第1のビート信号を生成する第1の検出手段
と、前記第2の回折格子から生じる光ヘテロダイン干渉
回折光を検出して第2のビート信号を生成する第2の検
出手段と、それら第1および第2のビート信号に応じて
前記移動機構に制御信号を送り出し、前記第1および第
2の物体を相対的に動かして位置合わせする信号処理制
御手段とを具備してなることを特徴としている。In addition, the alignment device of the second invention makes the first diffraction grating provided on the first object, the second diffraction grating provided on the second object, and the first and second objects relative to each other. A moving mechanism for moving the same, a light source for generating monochromatic light of two wavelengths whose frequencies are slightly different from each other, and a monochromatic light of two wavelengths generated from the light source for each of the first and second diffraction gratings. Angle adjusting means for making the light incident at an incident angle, first detecting means for detecting optical heterodyne interference diffracted light generated from the first diffraction grating, and generating a first beat signal, and the second diffraction grating. Second detection means for detecting the optical heterodyne interference diffracted light generated from the second beat signal and a control signal sent to the moving mechanism according to the first and second beat signals, and the first detection means. And the second object relatively It is characterized by comprising and a signal processing control means for aligning However in position.
本発明は、第1および第2の回折格子のそれぞれに対し
て入射光を入射して、それらの回折格子のそれぞれから
独立して光ヘテロダイン干渉回折光を検出する。そし
て、それらの干渉光からそれぞれ得たビート信号の位相
差を測定することによって、第1および第2の物体の回
折格子ピッチ方向の相対的な位置合わせを行う。According to the present invention, incident light is incident on each of the first and second diffraction gratings, and the optical heterodyne interference diffracted light is detected independently from each of those diffraction gratings. Then, by measuring the phase difference of the beat signals respectively obtained from the interference lights, the relative alignment of the first and second objects in the diffraction grating pitch direction is performed.
以下、第1図ないし第3図を参照して本発明の実施例を
説明する。An embodiment of the present invention will be described below with reference to FIGS.
第1図は、本発明に係る位置合わせ装置の一実施例、す
なわち半導体ICやLSIを製造するためのX線露光装置の
概略構成を示すものである。第1図において、20は周波
数が互いにわずかに異なり、偏光面方向が互いに直交す
る2波長の光を発する2波長直交偏光レーザー光源(光
源)、21,21′,21″,21はミラーであり、これらのミ
ラーのうちミラー21′,21″は角度調整自在とされてい
る。22は円筒レンズ、23は偏光ビームスプリッター,24
はプリズム状ミラー、25,25′は集光レンズ、26,26′は
光検出器(第1,第2の検出手段)、27は信号処理制御部
(信号処理制御手段)、28はマスクステージ、29はウエ
ハステージ、30はマスク(第1の物体)、31はウエハ
(第2の物体)、32は反射型回折格子(第1の回折格
子)、33は単色光入射・回折光取り出し窓、34は反射型
回折格子(第2の回折格子)、44,44′は偏光板であ
る。ここで前記単色光入射・回折光取り出し窓33は、マ
スク30に設けられた開口部であり、この窓33を通して回
折格子34に対して入射光が直接入射でき、かつその回折
格子34からの回折光が直接取り出せるようになってい
る。また、マスクステージ28およびウエハステージ29
は、マスク30およびウエハ31を相対的に動かす移動機構
を構成している。FIG. 1 shows a schematic configuration of an embodiment of an alignment apparatus according to the present invention, that is, an X-ray exposure apparatus for manufacturing a semiconductor IC or LSI. In FIG. 1, 20 is a two-wavelength orthogonal polarization laser light source (light source) that emits light of two wavelengths whose frequencies are slightly different from each other and whose polarization plane directions are orthogonal to each other, and 21,21 ′, 21 ″, 21 are mirrors. Of these mirrors, the mirrors 21 ', 21 "are adjustable in angle. 22 is a cylindrical lens, 23 is a polarization beam splitter, 24
Is a prismatic mirror, 25 and 25 'are condenser lenses, 26 and 26' are photodetectors (first and second detecting means), 27 is a signal processing control section (signal processing control means), and 28 is a mask stage. , 29 is a wafer stage, 30 is a mask (first object), 31 is a wafer (second object), 32 is a reflection type diffraction grating (first diffraction grating), and 33 is a monochromatic light incident / diffracted light extraction window. , 34 are reflection type diffraction gratings (second diffraction gratings), and 44, 44 'are polarizing plates. Here, the monochromatic light incident / diffracted light extraction window 33 is an opening provided in the mask 30, through which the incident light can be directly incident on the diffraction grating 34, and the diffraction from the diffraction grating 34 can be performed. The light can be taken out directly. Further, the mask stage 28 and the wafer stage 29
Constitute a moving mechanism for relatively moving the mask 30 and the wafer 31.
第1図において、2波長直交偏光レーザー光源20から発
した光は、ミラー21、円筒レンズ22を通して楕円状のビ
ームとなり、そのビームは偏光ビームスプリッター23に
より、それぞれ水平成分、あるいは垂直成分のみを有す
る直線偏光でしかも周波数が互いにわずかに異なる2波
長の光に分割され、分割された光はそれぞれミラー2
1′,21″(入射角調整手段)を介して所望の入射角で反
射型回折格子32,および反射型回折格子34に入射する。
第1図の例では、反射型回折格子32,34はそれぞれ格子
ライン方向にずれており、しかも2波長の入射光の同一
楕円ビーム内に配置されている。また、反射型回折格子
32,34の回折格子ピッチは等しくされている。回折格子3
2から得られる回折光および単色光入射・回折光取り出
し窓33を通して回折格子34から得られる回折光は、ミラ
ー21(光合成手段)、プリズム状ミラー24(光分離手
段)、集光レンズ25,25′、偏光板44,44′を介して光検
出器26,26′にそれぞれ導かれ、回折光ビート信号とし
て信号処理制御部27で処理される。信号処理制御部27で
は、反射型回折格子32,34から得られた回折光のそれぞ
れのビート信号のいずれか一方の信号を基準ビート信号
として両ビート信号の位相差を検出し、位相差が0゜に
なるようにマスクステージ28,あるいはウエハステージ2
9を相対移動させ、マスク面上のパタンがウエハ面上の
所定の位置に精度よく重なって露光できるようにマスク
30とウエハ31との間の精密な位置合わせを行なうように
されている。In FIG. 1, the light emitted from the two-wavelength orthogonal polarization laser light source 20 becomes an elliptical beam through the mirror 21 and the cylindrical lens 22, and the beam has only a horizontal component or a vertical component by the polarization beam splitter 23. It is split into two linearly polarized lights with slightly different frequencies, and the split lights are each reflected by the mirror 2
The light is incident on the reflective diffraction grating 32 and the reflective diffraction grating 34 at a desired incident angle via 1 ', 21 "(incident angle adjusting means).
In the example of FIG. 1, the reflection type diffraction gratings 32 and 34 are displaced in the grating line direction, and are arranged in the same elliptical beam of incident light of two wavelengths. Also, a reflection type diffraction grating
The diffraction grating pitches of 32 and 34 are made equal. Diffraction grating 3
The diffracted light obtained from 2 and the diffracted light obtained from the diffraction grating 34 through the monochromatic light incident / diffracted light extraction window 33 are mirror 21 (light combining means), prismatic mirror 24 (light separating means), and condenser lenses 25 and 25. ′ Is guided to the photodetectors 26 and 26 ′ via the polarizing plates 44 and 44 ′, respectively, and processed by the signal processing control unit 27 as a diffracted light beat signal. The signal processing control unit 27 detects the phase difference between both beat signals by using one of the beat signals of the diffracted light obtained from the reflection type diffraction gratings 32 and 34 as a reference beat signal, and the phase difference is 0. Mask stage 28 or wafer stage 2
9 is moved relative to the mask so that the pattern on the mask surface can be accurately overlapped at a predetermined position on the wafer surface for exposure.
A precise alignment between 30 and wafer 31 is provided.
次に、このように構成された位置合わせ装置による位置
合わせ方法を第2図を参照して説明する。第2図におい
て、35は反射型回折格子(第1の回折格子)、36は反射
型回折格子(第2の回折格子)、37,38は周波数が互い
にわずかに異なる2波長の入射光、39,40は回折光(光
ヘテロダイン干渉回折光)、41はマスク(第1の物体)
および回折格子35を構成する透明薄膜、42はウエハ、43
は不透明薄膜である。また、B1−B1′は第2の回折格子
の格子ライン方向、B2−B2′は第1の回折格子の格子ラ
イン方向、A1−A1′はB1−B1′に垂直な格子ピッチ方
向、A2−A2′はB2−B2′に垂直な格子ピッチ方向、C1−
C1′は回折格子36の格子面に対して垂直な方向、C2−
C2′は回折格子35の格子面に対して垂直な方向である。
第2図の例では第1,第2の回折格子35,36のピッチはい
ずれもPと等しくされており、また、回折格子35は回折
格子36の格子面と重ならないようにB2−B2′方向(格子
ライン方向)にずらして配置され、回折格子36の垂直方
向上方には前記取り出し窓33(第2図では図示略)が設
けられている。そして、入射光37,38の入射方向は、前
記ミラー21′,21″の角度を調節することにより、回折
格子に垂直な方向C1−C1′(あるいはC2−C2′)に対し
て回折格子35,36のそれぞれの±1次反射回折光の角度
θ-1=sin-1(λ1/P),θ+1=sin-1(λ2/P)に設定さ
れている。ここで入射光37,38の波長はそれぞれλ1,λ
2であり、周波数差Δfは数KHzから数百MHz程度の値で
あり、光速をCとするΔf=C・|1/λ1−1/λ2|とな
りΔf<<Cであるためθ-1≒θ+1となる。Next, a positioning method using the positioning device thus configured will be described with reference to FIG. In FIG. 2, 35 is a reflection type diffraction grating (first diffraction grating), 36 is a reflection type diffraction grating (second diffraction grating), 37 and 38 are two wavelengths of incident light whose frequencies are slightly different from each other, 39 , 40 is diffracted light (optical heterodyne interference diffracted light), 41 is a mask (first object)
And a transparent thin film constituting the diffraction grating 35, 42 is a wafer, 43
Is an opaque thin film. Further, B 1 -B 1 ′ is the grating line direction of the second diffraction grating, B 2 -B 2 ′ is the grating line direction of the first diffraction grating, and A 1 -A 1 ′ is B 1 -B 1 ′. vertical grating pitch direction, a 2 -A 2 'is B 2 -B 2' perpendicular grating pitch direction, C 1 -
C 1 ′ is the direction perpendicular to the grating plane of the diffraction grating 36, and C 2 −
C 2 ′ is the direction perpendicular to the grating plane of the diffraction grating 35.
In the example of FIG. 2, the pitches of the first and second diffraction gratings 35 and 36 are made equal to P, and the diffraction grating 35 is B 2 -B so as not to overlap with the grating surface of the diffraction grating 36. The take-out window 33 (not shown in FIG. 2) is provided above the diffraction grating 36 in the vertical direction above the diffraction grating 36. The incident directions of the incident lights 37 and 38 are adjusted by adjusting the angles of the mirrors 21 ′ and 21 ″ with respect to the direction C 1 −C 1 ′ (or C 2 −C 2 ′) perpendicular to the diffraction grating. Are set to the angles θ −1 = sin −1 (λ 1 / P) and θ +1 = sin −1 (λ 2 / P) of the ± first-order reflected diffracted lights of the diffraction gratings 35 and 36, respectively. Here, the wavelengths of the incident lights 37 and 38 are λ 1 and λ, respectively.
2, the frequency difference Delta] f is the value of the order of several hundred MHz from a few KHz, Δf = C · the speed of light as C | 1 / λ 1 -1 / λ 2 | for a next Δf << C θ - 1 ≈ θ +1 .
こうすることにより、回折格子35,36に入射した入射光3
7,38はそれぞれ反射型回折格子35,36でそれぞれ格子面
に垂直な方向(C2−C2′,C1−C1′方向)に−1次反射
回折されて光学的に合成され、それぞれ光ヘテロダイン
干渉回折光39,40となる。これらの光ヘテロダイン干渉
回折光39,40は、異なる回折格子35,36によって回折した
回折光であるが、入射光37,38の入射角が格子面の垂直
方向に対して左右対称であるため、回折格子35,36はそ
れぞれ垂直方向(C1−C1′,C2−C2′方向)、格子ライ
ン方向(B1−B1′,B2−B2′方向)にずれて配置されて
はいるが、入射光37と入射光38の回折格子35あるいは回
折格子36へ入射するまでの光路長変化は等しくなり、回
折光39,40から得られるビート信号の位相差には、回折
格子35,36の鉛直方向,格子ライン方向の変位に対する
位相ずれの影響を受けない。すなわち、回折光39,40か
ら得られるビート信号の位相差は回折格子35と回折格子
36のピッチ方向(A2−A2′,A1−A1′方向)に対しての
空間的配置、すなわち相対的変位量に応じてのみ変化す
る。そして、回折格子35,36が、格子ライン方向(B1−B
1′あるいはB2−B2′方向)に一直線となったとき、回
折光39,40から得られるビート信号の位相差は0゜とな
り、位置合わせが完了する。なお、A1−A1′あるいはA2
−A2′方向に対しての回折格子35,36の相対的変位量を
Δxとし、ビート信号位相差をΔφとすると の関係にあり、位相差Δφは、回折格子のピッチの1/2
の相対的変位量を同期として変わる。By doing so, the incident light 3 incident on the diffraction gratings 35 and 36
Reference numerals 7 and 38 denote reflection diffraction gratings 35 and 36, respectively, which are -1st-order reflected and diffracted in a direction (C 2 -C 2 ′, C 1 -C 1 ′ direction) perpendicular to the grating surface, and are optically synthesized. The light becomes heterodyne interference diffracted lights 39 and 40, respectively. These optical heterodyne interference diffracted lights 39, 40 are diffracted lights diffracted by different diffraction gratings 35, 36, but since the incident angles of the incident lights 37, 38 are symmetrical with respect to the vertical direction of the grating surface, The diffraction gratings 35 and 36 are arranged in the vertical direction (C 1 −C 1 ′, C 2 −C 2 ′ direction) and the grating line direction (B 1 −B 1 ′, B 2 −B 2 ′ direction), respectively. However, the change in the optical path length of the incident light 37 and the incident light 38 until they are incident on the diffraction grating 35 or the diffraction grating 36 becomes equal, and the phase difference between the beat signals obtained from the diffracted lights 39 and 40 is determined by the diffraction grating. The phase shift does not affect the displacement of 35 and 36 in the vertical and grid line directions. That is, the phase difference between the beat signals obtained from the diffracted lights 39 and 40 is the diffraction grating 35 and the diffraction grating.
It changes only according to the spatial arrangement of 36 pitch directions (A 2 −A 2 ′, A 1 −A 1 ′ direction), that is, relative displacement. Then, the diffraction gratings 35 and 36 are arranged in the grating line direction (B 1 -B
1 'or B 2 -B 2' when it becomes aligned in the direction), the phase difference of the beat signal obtained from the diffracted light 39 and 40 becomes 0 degrees, the alignment is completed. Note that A 1 −A 1 ′ or A 2
Let Δx be the relative displacement of the diffraction gratings 35 and 36 with respect to the −A 2 ′ direction, and Δφ be the beat signal phase difference. The phase difference Δφ is 1/2 of the diffraction grating pitch.
Changes relative to the relative displacement.
以上で説明したように、この実施例の装置によれば、第
1の物体と第2の物体に設けた第1および第2の回折格
子が平面視において互いに重ならないように格子ライン
方向にずらして配置することにより、第1の回折格子か
ら得られる光ヘテロダイン干渉回折光と第2の回折格子
から得られる光ヘテロダイン干渉回折光とを完全に独立
して検出できる。そして、両回折光から得られるビート
信号の位相差を検出することにより、第1の物体と第2
の物体の回折格子ピッチ方向の相対変位量に対応した位
相差を直接かつ安定的に検出でき、その位相差を0゜に
することにより、精密な位置合わせを安定して行なうこ
とができる。As described above, according to the device of this embodiment, the first and second diffraction gratings provided on the first object and the second object are displaced in the grating line direction so as not to overlap each other in plan view. The optical heterodyne interference diffracted light obtained from the first diffraction grating and the optical heterodyne interference diffracted light obtained from the second diffraction grating can be detected completely independently. Then, by detecting the phase difference between the beat signals obtained from both diffracted lights, the first object and the second object are detected.
It is possible to directly and stably detect the phase difference corresponding to the relative displacement amount of the object in the diffraction grating pitch direction, and by setting the phase difference to 0 °, precise alignment can be stably performed.
また、回折格子へ入射する単色光を回折格子の格子面の
垂直方向に対して左右対称なn次回折角(nは正の整
数)の方向に設定し、第1,第2の回折格子を単色光の同
一スポット内に配置することにより、単色光が回折格子
に入射するまでに至る光学系の光路長変化による回折光
の位相ずれは、第1および第2の回折格子によって得ら
れたビート信号に同じ位相ずれとなって現われるため互
いにキャンセルされ、前記位相ずれの影響は現われな
い。したがって、2波長の光の光路長を高精度に設定す
る必要がなく、光学系調整が容易になるとともに、機構
系も簡単である。また、光学部品等の微小振動等による
光路長変化に伴う位相ずれも打ち消され、高安定な位相
差信号を取り出すことができる。In addition, the monochromatic light incident on the diffraction grating is set in the direction of the n-th order diffraction angle (n is a positive integer) symmetrical with respect to the vertical direction of the grating surface of the diffraction grating, and the first and second diffraction gratings are monochromatic. By arranging in the same spot of light, the phase shift of the diffracted light due to the change in the optical path length of the optical system until the monochromatic light enters the diffraction grating is the beat signal obtained by the first and second diffraction gratings. Since they appear as the same phase shift, they cancel each other out, and the influence of the phase shift does not appear. Therefore, it is not necessary to set the optical path lengths of the two-wavelength light with high accuracy, the optical system adjustment becomes easy, and the mechanical system becomes simple. Further, the phase shift due to the change in the optical path length due to the microvibration of the optical component or the like is canceled, and the highly stable phase difference signal can be taken out.
なお、上記実施例においては、1組の回折格子を用いた
場合を示したが、同様の回折格子をマスクおよびウエハ
面上の2個所以上の位置に設置し、第1図と同様の方法
を用いて回折光のビート信号を検出し、位相差をなくす
ようにマスクステージおよびウエハステージを制御する
ことにより、マスクとウエハとを回折格子面に平行な面
で回折格子に平行および垂直な方向の2軸X,Y,およびXY
面に垂直なZ軸を中心としたXY面の回転軸θの3軸につ
いて位置合わせを行なうこともできる。In the above embodiment, the case where one set of diffraction gratings is used is shown, but similar diffraction gratings are installed at two or more positions on the mask and the wafer surface, and the same method as in FIG. 1 is used. The beat signal of the diffracted light is detected using the mask stage and the wafer stage so as to eliminate the phase difference, so that the mask and the wafer are parallel to and perpendicular to the diffraction grating. 2-axis X, Y, and XY
It is also possible to perform alignment with respect to the three axes of the rotation axis θ of the XY plane centered on the Z axis perpendicular to the plane.
また、第1および第2の回折格子としては、吸収型回折
格子、位相型回折格子のいずれを用いてもよく、さらに
バイナリー回折格子に限定されることなく、正弦波状回
折格子、ブレーズ回折格子など種々の組み合わせが可能
である。The first and second diffraction gratings may be either absorption type diffraction gratings or phase type diffraction gratings, and are not limited to binary diffraction gratings, and sinusoidal diffraction gratings, blazed diffraction gratings, etc. Various combinations are possible.
さらに上記実施例では、単色光入射・回折光取り出し窓
としてマスク基板上に開口部を設けたが、開口部を設け
ることなく、入射光および回折光が透過し得る透明薄膜
の窓にした場合においても同様の効果を得ることができ
る。また、二つのヘテロダイン干渉回折光を分離するた
めにプリズム状ミラーを用いたが、2分割ディテクター
により直接的に検出しても同様の効果を得ることができ
る。Further, in the above-mentioned embodiment, the opening was provided on the mask substrate as a monochromatic light incident / diffracted light extraction window, but in the case of a transparent thin film window through which incident light and diffracted light can pass without providing an opening. Can also obtain the same effect. Further, although the prism-shaped mirror is used to separate the two heterodyne interference diffracted lights, the same effect can be obtained by directly detecting with a two-divided detector.
また、上記では、第1,第2の回折格子を格子ライン方向
にずらして配置した実施例を示したが、第1,第2の回折
格子を格子ライン方向に直角な方向(格子ピッチ方向)
にずらして配置した場合でも、あるいは格子ライン方向
および格子ピッチ方向の双方に対してずらして配置した
場合においても、同様の効果を得ることができる。Also, in the above, an example in which the first and second diffraction gratings are arranged so as to be displaced in the grating line direction has been shown, but the first and second diffraction gratings are arranged in a direction perpendicular to the grating line direction (grating pitch direction).
Similar effects can be obtained even when they are arranged in a staggered manner or when they are arranged in a staggered manner in both the lattice line direction and the lattice pitch direction.
さらに上記では、入射光の同一楕円ビームスポット内に
第1,第2の回折格子を配置するようにしたが、第1,第2
の回折格子にそれぞれ独立に2波長の単色光を入射させ
る場合においても、第1,第2の回折格子へ入射するそれ
ぞれの2波長の単色光の光路長差による位相差分を考慮
しておけば同様の効果を得ることができる。Further, in the above, the first and second diffraction gratings are arranged in the same elliptical beam spot of the incident light.
Even when two monochromatic light beams of two wavelengths are independently incident on each diffraction grating, it is necessary to consider the phase difference due to the optical path length difference of each monochromatic light beam of two wavelengths incident on the first and second diffraction gratings. The same effect can be obtained.
また上記では、第1および第2の回折格子の格子ピッチ
を等しくし、かつ、1次回折光の光ヘテロダイン干渉光
を利用する例を示したが、一般にはn次回折光(nは正
の整数)の光ヘテロダイン干渉光を用いても同様の効果
を得ることができるし、さらに、第1と第2の回折格子
ピッチを変えて、第1の回折格子のn次回折角が第2の
回折格子のm次回折角(mは正の整数)と等しくなるよ
うに設定し、第1の回折格子からのn次回折光の光ヘテ
ロダイン干渉光と第2の回折格子からのm次回折光の光
ヘテロダイン干渉光を用いても同様の効果を得ることが
できる。Further, in the above, the example in which the grating pitches of the first and second diffraction gratings are made equal and the optical heterodyne interference light of the first-order diffracted light is used is shown, but generally, the n-th order diffracted light (n is a positive integer). The same effect can be obtained by using the optical heterodyne interference light of, and the n-th diffraction angle of the first diffraction grating is changed to that of the second diffraction grating by changing the pitches of the first and second diffraction gratings. It is set to be equal to the m-th order diffraction angle (m is a positive integer), and the optical heterodyne interference light of the n-th order diffracted light from the first diffraction grating and the optical heterodyne interference light of the m-th order diffracted light from the second diffraction grating are set. Even if used, the same effect can be obtained.
さらに、入射方向と出射方向とを入れ変えて、第1およ
び第2の回折格子への2波長単色光の垂直入射に対して
±1次回折光(一般には±n次回折光)を用い、偏光板
を利用して+n次回折光と−n次回折光とについてそれ
ぞれ周波数の異なる2波長の回折光を取り出し、光学的
に合成して第1の回折格子からの光ヘテロダイン干渉
光,第2の回折格子からの光ヘテロダイン干渉光を用い
ても同様の効果を得ることができる。Further, by changing the incident direction and the outgoing direction, the ± 1st-order diffracted light (generally ± n-order diffracted light) is used for the vertical incidence of the two-wavelength monochromatic light on the first and second diffraction gratings, and the polarizing plate Of the + n-th order diffracted light and the −n-th order diffracted light, two diffracted lights having different frequencies are extracted and optically combined to obtain the optical heterodyne interference light from the first diffraction grating and the second diffraction grating. The same effect can be obtained by using the optical heterodyne interference light.
また上記では、基準ビート信号として第1の回折格子か
らの光ヘテロダイン干渉ビート信号,あるいは第2の回
折格子からの光ヘテロダイン干渉ビート信号のいずれか
一方を用いたが、第4図に示したような方法で、2波長
直交偏光レーザー光源20から発したレーザー光の一部を
ビームスプリッター等であらかじめ分離し、分離して得
られた2波長レーザー光を偏光板で光ヘテロダイン干渉
させて基準ビート信号とし、この基準ビート信号と第1
の回折格子からの光ヘテロダイン干渉ビート信号との位
相差、および基準ビート信号と第2の回折格子からの光
ヘテロダイン干渉ビート信号との位相差を検出し、両位
相差が等しくなるように前記マスクステージ28あるいは
ウエハステージ29を相対移動させてマスクとウエハとを
位置合わせする装置においても同様の効果を得ることが
できる。Further, in the above, either the optical heterodyne interference beat signal from the first diffraction grating or the optical heterodyne interference beat signal from the second diffraction grating is used as the reference beat signal, but as shown in FIG. In this method, a part of the laser light emitted from the two-wavelength orthogonal polarization laser light source 20 is separated in advance by a beam splitter or the like, and the two-wavelength laser light obtained by the separation is subjected to optical heterodyne interference with a polarizing plate to generate a reference beat signal. And this reference beat signal and the first
Detecting the phase difference between the optical heterodyne interference beat signal from the diffraction grating and the phase difference between the reference beat signal and the optical heterodyne interference beat signal from the second diffraction grating, and masking them so that both phase differences become equal. The same effect can be obtained in an apparatus that aligns the mask and the wafer by relatively moving the stage 28 or the wafer stage 29.
第3図は、本発明に係る位置合わせ装置の他の実施例を
示す。第3図において、45は2波長直交偏光レーザー光
源、46,47,48,49,50,51,52は平面ミラー、53はビームス
プリッター、54,55は偏光ビームスプリッター、56,56′
は集光レンズ、57,57′は偏光板、58,58′は光検出器、
59,59′はプレアンプ、60は検出信号処理部、61は位置
表示部、62はステージ駆動部、63は第1の回折格子、64
は第2の回折格子、65は第1の物体、66は第2の物体、
67は移動ステージである。FIG. 3 shows another embodiment of the alignment apparatus according to the present invention. In FIG. 3, 45 is a two-wavelength orthogonal polarization laser light source, 46, 47, 48, 49, 50, 51, 52 are plane mirrors, 53 is a beam splitter, 54, 55 are polarized beam splitters, 56, 56 '.
Is a condenser lens, 57 and 57 'are polarizing plates, 58 and 58' are photodetectors,
59 and 59 'are preamplifiers, 60 is a detection signal processing unit, 61 is a position display unit, 62 is a stage drive unit, 63 is a first diffraction grating, and 64 is a
Is the second diffraction grating, 65 is the first object, 66 is the second object,
67 is a moving stage.
この装置においては、2波長直交偏光レーザー光源45か
ら発したレーザー光の一部を平面ミラー46、ビームスプ
リッター53を介して取り出し、偏光ビームスプリッター
54を用いてP偏光、S偏光の2波長の単色光に分離し、
平面ミラー47,48を介してそれぞれ所定の角度で第1の
回折格子63に入射し、回折格子63からの2波長の回折光
を光学的に合成し、平面ミラー49、集光レンズ56、偏光
板57を介して光検出器58で検出し、光ヘテロダイン干渉
基準ビート信号としてプレアンプ59を通して検出信号処
理部60へ入力する。一方、ビームスプリッター53により
分割された他のレーザー光は、偏光ビームスプリッター
55を用いてP偏光,S偏光の2波長の単色光に分離され、
平面ミラー50,51を介してそれぞれ所定の角度で第2の
回折格子64に入射する。回折格子64からの2波長の回折
光を光学的に合成し、平面ミラー52,集光レンズ56′,
偏光板57′を介して光検出器58′で検出し、光ヘテロダ
イン干渉の回折光ビート信号としてプレアンプ59′を通
して検出信号処理部60へ入力する。検出信号処理部60で
は、基準ビート信号と回折光ビート信号との位相差を検
出し、位相差に対応した回折格子63と回折格子64との相
対偏位量を位置表示部61で表示する。さらに位相差が一
定となるように制御信号をステージ駆動部62を介して移
動ステージ67に送り、第2の物体66を所定の位置にサー
ボ制御する。すなわち、この実施例の装置においては、
第1の物体65の位置を基準として、その第1の物体65に
対する第2の物体66の変位量を検出することによって、
位置合わせを行なうことができる。In this device, a part of the laser light emitted from the two-wavelength orthogonal polarization laser light source 45 is taken out through the plane mirror 46 and the beam splitter 53, and the polarization beam splitter is used.
54 is used to separate into P-polarized light and S-polarized light of two wavelengths,
The light is incident on the first diffraction grating 63 at a predetermined angle via the plane mirrors 47 and 48, and the two wavelengths of diffracted light from the diffraction grating 63 are optically combined to form a plane mirror 49, a condenser lens 56, and a polarized light. The light is detected by the photodetector 58 via the plate 57, and is input to the detection signal processing unit 60 through the preamplifier 59 as an optical heterodyne interference reference beat signal. On the other hand, the other laser light split by the beam splitter 53 is the polarized beam splitter.
55 is used to separate P-polarized light and S-polarized light of two wavelengths,
The light enters the second diffraction grating 64 at a predetermined angle via the plane mirrors 50 and 51. The two wavelengths of diffracted light from the diffraction grating 64 are optically combined to form a plane mirror 52, a condenser lens 56 ',
The light is detected by the photodetector 58 'through the polarizing plate 57', and is input to the detection signal processing unit 60 through the preamplifier 59 'as a diffracted light beat signal of optical heterodyne interference. The detection signal processing unit 60 detects the phase difference between the reference beat signal and the diffracted light beat signal, and the position display unit 61 displays the relative deviation amount between the diffraction grating 63 and the diffraction grating 64 corresponding to the phase difference. Further, a control signal is sent to the moving stage 67 via the stage drive unit 62 so that the phase difference becomes constant, and the second object 66 is servo-controlled to a predetermined position. That is, in the device of this embodiment,
By detecting the displacement amount of the second object 66 with respect to the first object 65 with reference to the position of the first object 65,
Alignment can be performed.
以上詳細に説明したように、本発明によれば、第1の物
体と第2の物体に設けた第1、第2の回折格子のそれぞ
れに対して2波長の単色光を入射して、両回折格子から
の回折光をそれぞれ検出し、それらの干渉光から生成し
たビート信号の位相差を測定するようにしたので、両物
体の回折格子ピッチ方向の相対的な位置合わせをそれら
の絶対座標による位置関係とは無関係に行うことができ
る。したがって、位置合わせに先立っていずれか一方の
物体を基準位置に正確に設定するための手間を省くこと
ができるとともに、その設定誤差に起因する位置合わせ
精度の低下を防止でき、さらにはその設定のための独立
した光学系を必要としないから装置を簡単に構成するこ
とができるという効果を奏する。As described in detail above, according to the present invention, monochromatic light of two wavelengths is incident on each of the first and second diffraction gratings provided on the first object and the second object, and both Since the diffracted light from the diffraction grating is detected and the phase difference of the beat signal generated from the interference light is measured, the relative alignment of both objects in the diffraction grating pitch direction is determined by their absolute coordinates. It can be performed regardless of the positional relationship. Therefore, it is possible to save the trouble of accurately setting either one of the objects at the reference position prior to the alignment, and prevent the alignment accuracy from deteriorating due to the setting error. Since there is no need for an independent optical system for the purpose, the device can be easily configured.
また本発明では、それぞれの回折格子からの一重回折光
を検出するので、得られる回折光の強度は二重回折光を
検出する従来の場合に比して高いという利点がある。Further, according to the present invention, since the single-diffracted light from each diffraction grating is detected, the intensity of the obtained diffracted light is higher than that in the conventional case where the double-diffracted light is detected.
さらに、両回折格子を入射光の同一ビームスポット内に
配置してそれらに対して同一ビームを入射するようにす
れば、それぞれの回折格子に入射する入射光の光路長を
正確に合わせる必要はなく、極めて簡便に位置合わせを
行うことが可能となる。Furthermore, by disposing both diffraction gratings in the same beam spot of the incident light so that the same beam is incident on them, it is not necessary to accurately match the optical path lengths of the incident light incident on the respective diffraction gratings. It becomes possible to perform the alignment very easily.
なお本発明は位置合わせのみならず、ある物体の微小変
位を測定する装置、座標位置検出または制御装置等に対
しても適用することが可能である。The present invention can be applied not only to alignment but also to a device for measuring a minute displacement of an object, a coordinate position detection or control device, and the like.
第1図ないし第3図は本発明の実施例を示す図である。
第1図および第2図は一実施例の位置合わせ装置を示
し、第1図はその概略構成を示す斜視図、第2図は回折
格子部の拡大斜視図である。第3図はこの発明の他の実
施例の位置合わせ装置の概略構成を示す立面図である。 第4図および第5図は従来の位置合わせ装置を示し、第
4図はその概略構成を示す立面図、第5図はその回折格
子部の拡大図である。 20……2波長直交偏光レーザー光源(光源)、 21′,21″……ミラー(入射角調整手段)、 26……光検出器(第1の検出手段)、 26′……光検出器(第2の検出手段)、 27……信号処理制御部(信号処理制御手段)、 28……マスクステージ、 29……ウエハステージ、 30,41……マスク(第1の物体)、 31,42……ウエハ(第2の物体)、 32,35……反射型回折格子(第1の回折格子)、 34,36……反射型回折格子(第2の回折格子)、 37,38……入射光、 39,40……回折光(光ヘテロダイン干渉回折光)、 45……2波長直交偏光レーザー光源(光源)、 47,48,50,51……ミラー(入射角調整手段)、 58……光検出器(第1の検出手段)、 58′……光検出器(第2の検出手段)、 60……検出信号処理部(信号処理制御手段)、 63……第1の回折格子、64……第2の回折格子、 65……第1の物体、66……第2の物体、67……移動ステ
ージ(移動機構)。1 to 3 are views showing an embodiment of the present invention.
1 and 2 show an alignment apparatus according to an embodiment, FIG. 1 is a perspective view showing a schematic configuration thereof, and FIG. 2 is an enlarged perspective view of a diffraction grating portion. FIG. 3 is an elevational view showing a schematic configuration of a positioning device according to another embodiment of the present invention. 4 and 5 show a conventional alignment device, FIG. 4 is an elevational view showing a schematic configuration thereof, and FIG. 5 is an enlarged view of a diffraction grating portion thereof. 20: 2 wavelength orthogonal polarization laser light source (light source), 21 ', 21 "... mirror (incident angle adjusting means), 26 ... photodetector (first detecting means), 26' ... photodetector ( Second detection means), 27 ... Signal processing control section (signal processing control means), 28 ... Mask stage, 29 ... Wafer stage, 30,41 ... Mask (first object), 31,42 ... ... Wafer (second object), 32,35 ... Reflective diffraction grating (first diffraction grating), 34,36 ... Reflective diffraction grating (second diffraction grating), 37, 38 ... Incident light , 39,40 …… Diffracted light (optical heterodyne interference diffracted light), 45 …… 2-wavelength orthogonal polarization laser light source (light source), 47,48,50,51 …… Mirror (incident angle adjusting means), 58 …… Optical light Detector (first detection means), 58 '... Photodetector (second detection means), 60 ... Detection signal processing unit (signal processing control means), 63 ... First diffraction grating, 64 ... … Second time Folded grid, 65 ... first object, 66 ... second object, 67 ... moving stage (moving mechanism).
Claims (2)
の物体に設けた第2の回折格子のそれぞれに対して、周
波数が互いにわずかに異なる2波長の単色光を入射し、
前記第1の回折格子から生じる光ヘテロダイン干渉回折
光を検出して第1のビート信号を生成するとともに、前
記第2の回折格子から生じる光ヘテロダイン干渉回折光
を検出して第2のビート信号を生成し、それら第1およ
び第2のビート信号の位相差を測定することによって、
前記第1および第2の物体の回折格子の回折格子ライン
に直角の回折格子ピッチ方向の相対変位量を検出するこ
とを特徴とする位置合わせ方法。1. A first diffraction grating and a second diffraction grating provided on a first object.
The monochromatic light of two wavelengths whose frequencies are slightly different from each other is incident on each of the second diffraction gratings provided on the object.
The optical heterodyne interference diffracted light generated from the first diffraction grating is detected to generate a first beat signal, and the optical heterodyne interference diffracted light generated from the second diffraction grating is detected to generate a second beat signal. By generating and measuring the phase difference between the first and second beat signals,
A method for alignment, comprising detecting a relative displacement amount in a diffraction grating pitch direction perpendicular to the diffraction grating lines of the diffraction gratings of the first and second objects.
2の物体に設けた第2の回折格子と、前記第1および第
2の物体を相対的に動かす移動機構と、周波数が互いに
わずかに異なる2波長の単色光を発生する光源と、前記
光源から発生した2波長の単色光を前記第1および第2
の回折格子のそれぞれに対して所定の入射角度で入射さ
せる入射角調整手段と、前記第1の回折格子から生じる
光ヘテロダイン干渉回折光を検出して第1のビート信号
を生成する第1の検出手段と、前記第2の回折格子から
生じる光ヘテロダイン干渉回折光を検出して第2のビー
ト信号を生成する第2の検出手段と、それら第1および
第2の検出手段によって生成された第1および第2のビ
ート信号に応じて前記移動機構に制御信号を送り出し、
前記第1および第2の物体を相対的に動かして位置合わ
せする信号処理制御手段とを具備してなることを特徴と
する位置合わせ装置。2. A first diffraction grating provided on a first object, a second diffraction grating provided on a second object, and a moving mechanism for relatively moving the first and second objects. A light source for generating monochromatic light of two wavelengths having frequencies slightly different from each other, and a monochromatic light of two wavelengths generated from the light source for the first and second
Incident angle adjusting means for making each of the diffraction gratings incident at a predetermined incident angle, and a first detection for generating the first beat signal by detecting the optical heterodyne interference diffracted light generated from the first diffraction grating. Means, second detecting means for detecting the optical heterodyne interference diffracted light generated from the second diffraction grating to generate a second beat signal, and first detecting means generated by the first and second detecting means. And sends a control signal to the moving mechanism in response to the second beat signal,
An alignment apparatus comprising: signal processing control means for performing relative alignment by moving the first and second objects relative to each other.
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61104186A JPH0749926B2 (en) | 1986-05-07 | 1986-05-07 | Alignment method and alignment device |
FR878706393A FR2598797B1 (en) | 1986-05-07 | 1987-05-06 | METHOD FOR MEASURING AND / OR ADJUSTING THE MOVEMENT OF AN OBJECT AND APPARATUS FOR CARRYING OUT THIS METHOD |
DE3715864A DE3715864C2 (en) | 1986-05-07 | 1987-05-07 | Method and device for detecting / setting a displacement |
US07/492,259 US5000573A (en) | 1986-05-07 | 1990-03-12 | Method of alignment with the use of diffraction gratings and an apparatus therefor |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP61104186A JPH0749926B2 (en) | 1986-05-07 | 1986-05-07 | Alignment method and alignment device |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS62261003A JPS62261003A (en) | 1987-11-13 |
JPH0749926B2 true JPH0749926B2 (en) | 1995-05-31 |
Family
ID=14373961
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP61104186A Expired - Fee Related JPH0749926B2 (en) | 1986-05-07 | 1986-05-07 | Alignment method and alignment device |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0749926B2 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20190038863A (en) * | 2016-08-01 | 2019-04-09 | 델타 디자인, 인코포레이티드 | IMAGE-based IC tray pocket detection system |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2517027B2 (en) * | 1987-12-18 | 1996-07-24 | 日本電信電話株式会社 | Moving amount measuring method and moving amount measuring device |
US5171999A (en) * | 1989-02-28 | 1992-12-15 | Nikon Corporation | Adjustable beam and interference fringe position |
US5070250A (en) * | 1989-02-28 | 1991-12-03 | Nikon Corporation | Position detection apparatus with adjustable beam and interference fringe positions |
US5489986A (en) * | 1989-02-28 | 1996-02-06 | Nikon Corporation | Position detecting apparatus |
DE4031637C2 (en) * | 1989-10-06 | 1997-04-10 | Toshiba Kawasaki Kk | Arrangement for measuring a displacement between two objects |
JP2890943B2 (en) * | 1990-11-30 | 1999-05-17 | キヤノン株式会社 | Position detecting method and position detecting device using the same |
DE69324532T2 (en) * | 1992-07-15 | 1999-09-23 | Nikon Corp., Tokio/Tokyo | Light source for a heterodyne interferometer |
JP2787303B2 (en) * | 1996-11-05 | 1998-08-13 | 株式会社ニコン | Positioning apparatus, exposure apparatus and exposure method |
JP4208277B2 (en) * | 1997-11-26 | 2009-01-14 | キヤノン株式会社 | Exposure method and exposure apparatus |
JP2006165371A (en) | 2004-12-09 | 2006-06-22 | Canon Inc | Transfer apparatus and device manufacturing method |
-
1986
- 1986-05-07 JP JP61104186A patent/JPH0749926B2/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR20190038863A (en) * | 2016-08-01 | 2019-04-09 | 델타 디자인, 인코포레이티드 | IMAGE-based IC tray pocket detection system |
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JPS62261003A (en) | 1987-11-13 |
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