JPH1026513A - Instrument and method for measuring surface position of sample - Google Patents
Instrument and method for measuring surface position of sampleInfo
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- JPH1026513A JPH1026513A JP18355496A JP18355496A JPH1026513A JP H1026513 A JPH1026513 A JP H1026513A JP 18355496 A JP18355496 A JP 18355496A JP 18355496 A JP18355496 A JP 18355496A JP H1026513 A JPH1026513 A JP H1026513A
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- Japan
- Prior art keywords
- sample
- light
- measurement surface
- light beams
- measurement
- Prior art date
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、半導体ウエハある
いはマスクなどの試料の表面位置を非接触で測定する試
料面位置測定装置及び測定方法に関する。[0001] 1. Field of the Invention [0002] The present invention relates to a sample surface position measuring apparatus and method for measuring a surface position of a sample such as a semiconductor wafer or a mask in a non-contact manner.
【０００２】[0002]
【従来の技術】近年、ＬＳＩの高集積化に伴い、半導体
装置に要求される回路線幅は、ますます狭くなってきて
いる。これらの半導体装置は、所望の回路パターンが形
成された数十種類の原画パターン（レチクルあるいはマ
スク）を、ウエハ上の露光領域に高精度に位置合わせし
た後、転写を繰り返して作成される。この転写の際に用
いられる装置は、高精度な光学系を有する縮小投影露光
装置で、転写される側のウエハ全面に露光できるよう
に、ウエハ側は高精度なＸＹステージ上に固定されてい
る。このウエハが光学系に対しステップ＆リピートする
ために、掲記転写装置はステッパとも呼ばれている。2. Description of the Related Art In recent years, with high integration of LSIs, circuit line widths required for semiconductor devices have become increasingly smaller. These semiconductor devices are produced by repeatedly transferring a dozens of original patterns (reticles or masks) on which a desired circuit pattern is formed on an exposure region on a wafer with high precision. The apparatus used for this transfer is a reduction projection exposure apparatus having a high-precision optical system, and the wafer side is fixed on a high-precision XY stage so that the entire surface of the wafer to be transferred can be exposed. . Because the wafer steps and repeats with respect to the optical system, the transfer device described above is also called a stepper.
【０００３】ステッパの縮小率は、従来５分の１のもの
が主流であった。これまで光の波長限界から、１μｍ以
下のパターンは解像できないといわれてきたが、光学系
・照明系の改良やレチクル上で光の位相を調整する位相
シフトマスク等の出現により、サブμｍパターンを解像
するに至っている。解像度の向上に伴い、縮小レンズの
焦点深度が減少し、あらかじめウエハ上に形成されたパ
ターン上に原画パターンを転写する精度には一層厳しい
値が要求されるため、ステッパのアライメント光学系に
は試料の位置を試料面方向と焦点方向に高精度に検出す
ることが求められるようになっている。[0003] Conventionally, the reduction ratio of the stepper has been mainly one-fifth. Until now, it has been said that patterns of 1 μm or less cannot be resolved due to the wavelength limit of light. However, due to improvements in optical systems and illumination systems, and the emergence of phase shift masks that adjust the phase of light on a reticle, sub-μm patterns have been developed. Has been resolved. As the resolution increases, the depth of focus of the reduction lens decreases, and the accuracy of transferring the original pattern onto the pattern formed on the wafer in advance requires a stricter value. Is required to be detected with high accuracy in the direction of the sample surface and in the direction of the focal point.
【０００４】原画パターンは、高精度に仕上げられたガ
ラス基板上に描かれ、レジストプロセス等を経てＣｒ
（クロム）のパターンとして形成される。通常は、片面
にＣｒを蒸着したガラス基板上にレジストを均一に塗布
したものを使用する。パターン描画装置の集束した電子
あるいはレーザー等を光源としたエネルギービームが基
板上の所望の領域のレジストに照射され、設計データに
従いビームスポットが基板の全面を走査する。そして、
上記エネルギービームの照射によって変質したレジスト
を使って、Ｃｒのエッチングを場所によって抑止させ、
所望のＣｒパターンを得る。また、このとき絞られたビ
ームスポットを繋いで一つのパターンを形成して行くた
め、ビームのコントロール次第では高精度にパターンを
形成することが可能となっている。上記ビームスポット
の解像度向上のために、光源には一層の高加速電圧化が
求められている。[0004] The original pattern is drawn on a glass substrate which has been finished with high precision, and is subjected to a resist process or the like to obtain a Cr pattern.
(Chrome) pattern. Usually, a material obtained by uniformly coating a resist on a glass substrate having Cr evaporated on one side is used. An energy beam using a focused electron or laser of a pattern drawing apparatus as a light source is applied to a resist in a desired region on the substrate, and a beam spot scans the entire surface of the substrate according to design data. And
Using the resist altered by the irradiation of the energy beam, the etching of Cr is suppressed in some places,
Obtain a desired Cr pattern. At this time, since one pattern is formed by connecting the focused beam spots, it is possible to form the pattern with high accuracy depending on the beam control. In order to improve the resolution of the beam spot, the light source is required to have a higher accelerating voltage.
【０００５】また、解像度の向上に伴い、前記Ｃｒパタ
ーン上の露光光透過部を通過する光の位相、即ち透過部
の光路長を、基板の厚さをエッチングにより減少させ
る、或いは屈折率の異なる材料を付加するなどの手法に
より部分的に変化させる、いわゆる位相シフトマスクが
提案されている（特開平６−２２２１９０号公報な
ど）。位相シフトマスクの作成にあたっては、あらかじ
めＣｒパターンが形成されたガラス基板に再度レジスト
を塗布し、光透過部の位相を部分的に変化させるための
材料を付加した後、不要部分のエッチングを行う方法、
または特定の光透過部のガラス基板を厚さ方向に堀り込
み、選択的に光路長を変化させる方法が採用される。そ
のため、前記パターン描画装置にて所定の位置のレジス
トを高精度に感光させる必要がある。[0005] With the improvement of resolution, the phase of light passing through the exposure light transmitting portion on the Cr pattern, that is, the optical path length of the transmitting portion, is reduced by etching the substrate thickness or changing the refractive index. A so-called phase shift mask in which a material is partially changed by a method such as adding a material has been proposed (JP-A-6-222190). When creating a phase shift mask, a method is used in which a resist is applied again to a glass substrate on which a Cr pattern has been formed in advance, a material for partially changing the phase of the light transmitting portion is added, and then unnecessary portions are etched. ,
Alternatively, a method in which a glass substrate of a specific light transmitting portion is dug in the thickness direction to selectively change the optical path length is employed. Therefore, it is necessary to expose the resist at a predetermined position with high precision by the pattern drawing apparatus.
【０００６】パターン位置を検出するに当たり、電子ビ
ーム描画装置においては基板上に設けられた位置合わせ
マークを描画ビームで走査し、得られる反射電子などを
センサに取り込み、信号処理する方法が提案されている
（特開昭５８−２２３３２６号公報など）。しかし、こ
の方法では、（ａ）高加速ビームの照射により、位置合
わせマーク上のレジストがダメージを受ける、（ｂ）ダ
メージを受けたレジストが真空雰囲気を劣化させる、
（ｃ）レジスト層を介してマークを測定するため、信号
コントラストが低下するといった問題がある。前記
（ａ）〜（ｃ）の問題を回避するため、あらかじめマー
ク部分のレジストを削除する方法もあるが、そのための
工程が必要となり、処理が煩雑になるという問題があ
る。In detecting a pattern position, a method of scanning an alignment mark provided on a substrate with a drawing beam in an electron beam drawing apparatus, taking in reflected electrons and the like into a sensor, and performing signal processing has been proposed. (JP-A-58-223326). However, in this method, (a) the resist on the alignment mark is damaged by the irradiation of the high acceleration beam, (b) the damaged resist deteriorates the vacuum atmosphere,
(C) Since the mark is measured via the resist layer, there is a problem that the signal contrast is reduced. In order to avoid the above-mentioned problems (a) to (c), there is a method of deleting the resist at the mark portion in advance. However, a process for that is necessary, and there is a problem that the processing becomes complicated.
【０００７】また、パターン位置を精度よく測定するた
めには、電子ビームの照射位置が時間経過によらず安定
に再現する必要がある。しかし、実際には電子ビームは
鏡筒内部に汚れが生じるとチャージアップによりドリフ
トが生じ、電子ビームがドリフトしていると測定値が変
動する。そこで、マスク上の位置合わせマーク検出に先
立ち、ビームの照射位置はステージ上に設けられたマー
クなどを用いて測定・校正される。これに対し、ステー
ジの位置はレーザー干渉計により高精度でモニターされ
るので、レーザー干渉計の座標系を基準として、ビーム
の照射位置や変位を測定することが可能となる。一方、
マスク上のマーク位置測定は、ステージ上のマークを介
した間接測定となるため、測定値に変動が生じたとき、
原因がビームドリフトなのか、マークそのものが変位し
ているかの区別ができないという問題がある。In order to accurately measure the pattern position, it is necessary to reproduce the irradiation position of the electron beam stably with time. However, the electron beam actually drifts due to charge-up when contamination occurs inside the lens barrel, and the measured value fluctuates when the electron beam drifts. Therefore, prior to the detection of the alignment mark on the mask, the beam irradiation position is measured and calibrated using a mark provided on the stage. On the other hand, since the position of the stage is monitored with high accuracy by the laser interferometer, it is possible to measure the irradiation position and displacement of the beam with reference to the coordinate system of the laser interferometer. on the other hand,
Since the measurement of the mark position on the mask is an indirect measurement via the mark on the stage, when the measurement value fluctuates,
There is a problem that it cannot be distinguished whether the cause is the beam drift or the mark itself is displaced.
【０００８】ところで、電子ビーム描画装置やステッパ
において、上記マークの位置を精度よく測定するための
方法として、レーザー光を用いた測定光学系を設ける方
法が知られている。しかし、高精度な測定のためには、
電子ビームまたは露光光を照射する位置で測定を行う必
要があるため、光学系の配置が難しい、装置が複雑にな
るといった問題がある。As a method for accurately measuring the position of the mark in an electron beam drawing apparatus or a stepper, there is known a method of providing a measuring optical system using laser light. However, for accurate measurement,
Since the measurement needs to be performed at the position where the electron beam or the exposure light is applied, there are problems that the arrangement of the optical system is difficult and the apparatus becomes complicated.
【０００９】[0009]
【発明が解決しようとする課題】上記のように従来の試
料面位置測定装置及び測定方法は、試料面の位置測定を
行うための構造が複雑になったり、処理が繁雑化し、電
子ビームによるレジストへのダメージやビームドリフト
の影響を受けて精度が低下するという問題があった。As described above, the conventional apparatus and method for measuring the position of a sample surface require a complicated structure for measuring the position of the sample surface, the processing becomes complicated, and the resist by electron beam is used. There is a problem that the accuracy is reduced due to the influence of damage to the laser beam and the beam drift.
【００１０】本発明は上記課題を解決するためになされ
たもので、簡単な構造で試料面の位置測定を行うことが
でき、電子ビームによるレジストへのダメージやビーム
ドリフトの影響のない高精度な試料面位置測定装置及び
測定方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can measure the position of a sample surface with a simple structure, and has high accuracy without damaging a resist by an electron beam or affecting beam drift. It is an object to provide a sample surface position measuring device and a measuring method.
【００１１】[0011]
【課題を解決するための手段】本発明は、基本的には先
願（特願平３−８２３１８号）の技術をベースにしてい
るが、比較的簡単な構造で十分に実用性のある試料面の
位置測定装置及び測定方法を実現している。The present invention is basically based on the technology of the prior application (Japanese Patent Application No. 3-82318), but has a relatively simple structure and a sufficiently practical sample. A surface position measuring device and a measuring method are realized.
【００１２】即ち、請求項１に記載した本発明の試料面
位置測定装置は、試料の測定面に可干渉性のある光を少
なくとも２本照射する手段と、前記試料の測定面で反射
または回折した光を検出器に導く手段と、検出器に導か
れた２光束に含まれる周波数の異なる光の波動の干渉に
より生じるうなりの位相を検出する手段とを具備し、前
記試料の測定面における法線方向の位置または前記試料
の測定面内で互いに直交する２方向の変位を検出するこ
とを特徴としている。That is, in the sample surface position measuring apparatus according to the present invention, there is provided a means for irradiating at least two coherent lights to a measurement surface of a sample, and a device for reflecting or diffracting light on the measurement surface of the sample. Means for guiding the sampled light to a detector, and means for detecting a beat phase caused by interference between waves of light having different frequencies contained in the two light beams guided to the detector. It is characterized in that displacements in two directions perpendicular to each other are detected in a position in a linear direction or in a measurement plane of the sample.
【００１３】請求項１に記載の試料面位置測定装置にお
いて、前記試料の測定面に照射される少なくとも２本の
光は、周波数がわずかに異なる波動が混在しているもの
であり、前記検出器に導かれる反射または回折した光の
うち、任意の２光束を組み合わせて互いに干渉するよう
に重ね合わせる光学手段と、前記２光束の波動の干渉に
より生じるうなりと等しい周波数を有する基準信号と前
記２光束の波動の干渉により生じるうなりの信号との位
相差を測定する測定手段とを更に具備し、前記試料の測
定面の法線方向の位置及び試料の測定面内で互いに直交
する２方向の変位を検出することが望ましい。3. The sample surface position measuring apparatus according to claim 1, wherein the at least two lights applied to the measurement surface of the sample are mixed with waves having slightly different frequencies. Optical means for combining any two of the reflected or diffracted light beams guided to each other and superimposing them so as to interfere with each other, a reference signal having a frequency equal to the beat generated by the interference of the waves of the two light beams, and the two light beams Measuring means for measuring a phase difference with a beat signal generated by interference of the wave of the sample, and a displacement in two directions orthogonal to each other in a position in a normal direction of the measurement surface of the sample and in a measurement surface of the sample. It is desirable to detect.
【００１４】また、請求項２に記載した本発明の試料面
位置測定装置は、測定面に回折光を２次元分布させる回
折格子が形成された試料に、測定面と平行な変位検出方
向のうちの一方と試料の測定面における法線方向とが成
す面に対し、互いに異なる方向から少なくとも２本の光
束を入射させるとともに、前記２本の光束に対し試料の
測定面の法線方向に異なる角度で少なくとも１本の光束
を入射させる試料面照射手段と、前記試料の測定面上に
設けられた回折格子から生じる反射回折光のうち任意の
２光束を組み合わせて互いに干渉するように重ね合わせ
る光学手段と、前記２光束の波動の干渉により生じるう
なりと等しい周波数を有する基準信号と前記２光束の波
動の干渉により生じるうなりの信号との位相差を測定す
る測定手段とを具備し、前記試料の測定面の法線方向の
位置及び試料の測定面内で互いに直交する２方向の変位
を検出することを特徴としている。According to a second aspect of the present invention, there is provided a sample surface position measuring apparatus according to the present invention, wherein a diffraction grating for forming a two-dimensional distribution of diffracted light is formed on a measurement surface. And at least two light beams from different directions are incident on a surface formed by one of the two and the normal direction of the measurement surface of the sample, and the angles of the two light beams are different from the normal direction of the measurement surface of the sample. Means for irradiating at least one light beam on the sample surface, and optical means for combining arbitrary two light beams among reflected diffracted light beams generated from a diffraction grating provided on the measurement surface of the sample so as to interfere with each other. And measuring means for measuring a phase difference between a reference signal having a frequency equal to the beat generated by the interference of the waves of the two light beams and a beat signal generated by the interference of the waves of the two light beams. And it is characterized by detecting the normal direction position and measuring plane in two orthogonal directions of the mutually displaced in the sample of the measurement surface of the sample.
【００１５】請求項２に記載の試料面位置測定装置にお
いて、前記測定面と平行な変位検出方向のうちの一方と
試料の測定面における法線方向とが成す面に対し、互い
に異なる方向から入射される少なくとも２本の光束は、
周波数がわずかに異なる波動が混在しているものである
ことが望ましい。3. The sample surface position measuring device according to claim 2, wherein the light is incident from different directions on a surface formed by one of the displacement detection directions parallel to the measurement surface and the normal direction on the measurement surface of the sample. The at least two luminous fluxes are
It is desirable that waves having slightly different frequencies coexist.
【００１６】請求項１または２に記載の試料面位置測定
装置において、前記試料の測定面に入射させる２光束を
それぞれ異なる偏光方向あるいは回転方向を持つように
偏光する偏光手段を更に具備し、それぞれの反射回折光
をこの偏光手段で分離した後に、前記光学手段に導いて
互いに干渉するよう重ね合わせること、前記試料の測定
面に入射させる少なくとも２本の光束と、入射角度が前
記試料の測定面の法線方向に異なる少なくとも１本の光
束の法線方向の角度差を調整する入射角度変更手段を更
に具備すること、前記試料の測定面に平行な変位検出方
向のうちの一方と試料の測定面の法線方向とが成す面に
対し、対称な方向から入射する２本の光束は、波長を
λ、Ｘ，Ｙ方向の回折格子のピッチをＰx ，Ｐy 、Ｘ方
向とＹ方向のｎ次の回折角をそれぞれθx ，θy とした
とき、“ｓｉｎθx ＝±λ／Ｐx ”、“ｓｉｎθ1 −ｓ
ｉｎθy ＝±λ／Ｐy ”と表され、Ｘ方向の入射角がα
（≠θx ）に設定されていることが望ましい。The apparatus for measuring the position of a sample surface according to claim 1 or 2, further comprising polarizing means for polarizing the two light beams incident on the measurement surface of the sample so as to have different polarization directions or rotation directions, respectively. After the reflected and diffracted light is separated by the polarizing means, the reflected and diffracted light is guided to the optical means and overlapped so as to interfere with each other. At least two light beams to be incident on the measurement surface of the sample, and the incident angle are measured on the measurement surface of the sample. Further comprising incident angle changing means for adjusting the angle difference in the normal direction of at least one light beam different from the normal direction of the light beam, measuring one of the displacement detection directions parallel to the measurement surface of the sample and measuring the sample. The two luminous fluxes incident from a direction symmetric with respect to the plane formed by the normal direction of the plane have wavelengths of λ, pitches of the diffraction grating in the X and Y directions of P x and P y , and X and Y directions. nth order The much trouble each θ x, when the θ y, "sinθ x = ± λ / P x", "sinθ 1 -s
inθ y = ± λ / P y ”, and the incident angle in the X direction is α
(≠ θ x ) is desirably set.
【００１７】請求項３に記載した本発明の試料面位置測
定装置は、試料の測定面に可干渉性のある光を少なくと
も２本照射する手段と、前記試料の測定面で反射または
回折した光を検出器に導く手段と、検出器に導かれた２
光束に含まれる周波数の異なる光の波動の干渉により生
じるうなりの位相を検出する手段とを具備し、荷電粒子
ビームを用いたパターン描画装置内に設けられた試料を
移動させるためのステージの位置、またはこのステージ
に載置された試料の測定面の位置を検出することを特徴
としている。According to a third aspect of the present invention, there is provided a sample surface position measuring apparatus for irradiating at least two coherent lights on a measurement surface of a sample, and a light reflected or diffracted on the measurement surface of the sample. To the detector, and 2
A means for detecting a beat phase caused by interference of waves of light having different frequencies included in the light flux, and a position of a stage for moving a sample provided in a pattern drawing apparatus using a charged particle beam, Alternatively, the position of the measurement surface of the sample placed on this stage is detected.
【００１８】更に、請求項４に記載した本発明の試料面
位置測定方法は、微小量異なる周波数で変調された少な
くとも２本の可干渉性のある光ビームを生成する第１の
ステップと、前記少なくとも２本の光ビームを試料の測
定面に照射する第２のステップと、前記試料の測定面で
反射または回折した少なくとも２本の光ビームを受光す
る第３のステップと、前記第３のステップで受光した光
ビームの光学的演算を行って選択的に重ね合わせる第４
のステップと、前記第４のステップで光学的演算を施し
た光信号を電気信号に変換する第５のステップと、前記
第５のステップで変換された電気信号と基準信号との位
相差を演算する第６のステップとを具備し、前記試料の
測定面における法線方向の位置または前記試料の測定面
内で互いに直交する２方向の変位を検出することを特徴
としている。Further, according to a fourth aspect of the present invention, in the method for measuring a sample surface position according to the present invention, a first step of generating at least two coherent light beams modulated by minute amounts different frequencies; A second step of irradiating the measurement surface of the sample with at least two light beams, a third step of receiving at least two light beams reflected or diffracted on the measurement surface of the sample, and the third step 4. Perform optical calculation of the light beam received at step 4 to selectively overlap
And a fifth step of converting the optical signal subjected to the optical operation in the fourth step into an electric signal, and calculating a phase difference between the electric signal converted in the fifth step and a reference signal. And detecting displacements in two directions orthogonal to each other in the normal direction on the measurement surface of the sample or in the measurement surface of the sample.
【００１９】上記のような構成並びに方法において、試
料の測定面で正反射された角度の異なる２光束を受光
し、この角度の差から、試料の測定面が高さ方向に変位
したとき、光路差が発生することにより２光束の位相が
変化する。この量を測定することで、特殊なマークを用
意することなく、試料の測定面の高さが測定できる。ま
た、光束を照射する試料の測定面に、回折光を２次元分
布させる回折格子を位置合わせマークとして設け、試料
の測定面に平行な変位検出方向のうちの一方と試料面の
法線方向とが成す面に対し対称な方向に出射する２本の
光束を受光し、回折角の差から試料の測定面がこの測定
面と平行な方向に変位したとき、光路差が発生して２光
束の位相が変化する。この量を測定することで、試料の
測定面内で互いに直交する２方向の変位を測定できる。In the configuration and method as described above, two light beams having different angles that are specularly reflected on the measurement surface of the sample are received, and when the measurement surface of the sample is displaced in the height direction from the difference between the angles, the optical path is determined. Due to the difference, the phases of the two light beams change. By measuring this amount, the height of the measurement surface of the sample can be measured without preparing a special mark. Also, a diffraction grating for two-dimensionally distributing the diffracted light is provided as an alignment mark on the measurement surface of the sample irradiated with the light beam, and one of the displacement detection directions parallel to the measurement surface of the sample and the normal direction of the sample surface are determined. Receives two light beams emitted in directions symmetrical with respect to the plane formed by the measurement, and when the measurement surface of the sample is displaced in a direction parallel to the measurement surface due to a difference in diffraction angle, an optical path difference occurs and the two light beams The phase changes. By measuring this amount, displacements in two directions perpendicular to each other can be measured in the measurement plane of the sample.
【００２０】上記構成並びに方法は、光ヘテロダインを
採用した位相測定のため、試料の測定面からの反射光量
の変化に依存しない位置測定が可能になる。また、光源
にレーザー光を採用しているため、チャージアップによ
るドリフトを生じず、安定した信号を得ることが可能と
なる。更に、上記構成の光学系により、試料面の位置を
高さ及び並進方向に検出することができるので、装置構
成を複雑にすることなく、高精度な位置検出が可能とな
る。In the above configuration and method, phase measurement using optical heterodyne allows position measurement independent of a change in the amount of reflected light from the measurement surface of the sample. In addition, since laser light is employed as the light source, a stable signal can be obtained without drift due to charge-up. Further, the position of the sample surface can be detected in the height and the translation direction by the optical system having the above configuration, so that highly accurate position detection can be performed without complicating the device configuration.
【００２１】[0021]
【発明の実施の形態】以下、本発明の実施の形態につい
て図面を参照して説明する。図１は、本発明の第１の実
施の形態に係る試料面位置測定装置及び測定方法につい
て説明するためのもので、（ａ）図はレーザー光の照射
側の概略構成図、（ｂ）図は試料の測定面の高さを測定
する場合の受光側の概略構成図、図２は図１（ａ），
（ｂ）における試料の測定面への入射光と反射光の関係
を詳細に示す斜視図である。Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are views for explaining a sample surface position measuring apparatus and a measuring method according to a first embodiment of the present invention, wherein FIG. 1A is a schematic configuration diagram on a laser beam irradiation side, and FIG. FIG. 2 is a schematic diagram of the light receiving side when measuring the height of the measurement surface of the sample, and FIG.
FIG. 3B is a perspective view showing in detail the relationship between incident light and reflected light on the measurement surface of the sample in FIG.
【００２２】図１（ａ）において、１はレーザー光を発
生する光源で、この光源１から出射された干渉性の強い
レーザー光は、ビームスプリッタ（ハーフミラー）２で
第一の光路と第二の光路とに分けられる。分けられた各
光束は音響光学変調素子（ＡＯＭ）３、４によってそれ
ぞれ微小量異なる周波数ｆ1 ，ｆ2 で変調される。ＡＯ
Ｍ３から出射された光束５はビームスプリッタ６でさら
に分けられ、第三の光束７を得るようになっている。こ
れら３本の光束５、７、８は、図示しない折り返しミラ
ーとレンズを介し、その内の２光束５、８が試料９の測
定面に対して所定の角度θ1 で、光束７はこれらの光束
５、８と入射角度差Δθをもって試料９の測定面に斜め
方向から照射される（図２参照）。なお、光束５と７、
８は互いに試料９の測定面に平行な変位検出方向のうち
一方の変位方向と試料９における測定面の法線方向が成
す面に対し対称な方向から角度αにて入射する。この２
光束７、８の正反射光１２、１０は図示するように高さ
方向に出射角度差Δθをもって分離したものとなる。一
方、光束５と８の正反射光１１、１０は高さ方向に等し
い出射角度で、試料９の測定面に平行な方向に角度差２
αをもって分離したものとなる。In FIG. 1A, reference numeral 1 denotes a light source for generating a laser beam. A laser beam having a strong coherence emitted from the light source 1 is passed through a beam splitter (half mirror) 2 to a first optical path and a second optical path. Optical path. The divided light fluxes are modulated by the acousto-optic modulators (AOMs) 3 and 4 at frequencies f 1 and f 2 that differ by a small amount, respectively. AO
The light beam 5 emitted from the M3 is further divided by a beam splitter 6, and a third light beam 7 is obtained. These three light beams 5, 7, and 8 pass through a folding mirror and a lens (not shown). Two of the light beams 5, 8 are at a predetermined angle θ 1 with respect to the measurement surface of the sample 9, and the light beam 7 is The measurement surface of the sample 9 is irradiated obliquely with the light beams 5, 8 and the incident angle difference Δθ (see FIG. 2). The luminous fluxes 5 and 7,
Numerals 8 are incident at an angle α from a direction symmetrical with respect to a plane formed by one of the displacement detection directions parallel to the measurement surface of the sample 9 and the normal direction of the measurement surface of the sample 9. This 2
The specularly reflected lights 12 and 10 of the light fluxes 7 and 8 are separated with an emission angle difference Δθ in the height direction as shown in the figure. On the other hand, the specularly reflected lights 11 and 10 of the light fluxes 5 and 8 have an emission angle equal to the height direction and an angle difference 2 in a direction parallel to the measurement surface of the sample 9.
separated by α.
【００２３】図１（ｂ）に示すように、試料９の測定面
で反射された２光束１０、１１と１０、１２をハーフミ
ラー１３、１４、１５を用いてそれぞれ重ね合わせるこ
とにより、波動の干渉により生じるうなりをセンサ１６
（これが高さ検出信号となる）とセンサ１７（これが基
準信号となる）で測定することが可能となる。これらの
信号の位相差を位相計１８を用いて測定し、変位信号を
得ることにより、位相差に比例した試料９の表面の高さ
を知ることができる。As shown in FIG. 1B, the two light beams 10, 11 and 10, 12 reflected on the measurement surface of the sample 9 are superimposed on each other by using half mirrors 13, 14, 15, respectively. The beat generated by the interference is detected by the sensor 16.
(This becomes the height detection signal) and the sensor 17 (this becomes the reference signal). By measuring the phase difference between these signals using the phase meter 18 and obtaining the displacement signal, the height of the surface of the sample 9 proportional to the phase difference can be known.
【００２４】試料９の測定面が高さＺだけ変位したとき
の２つの信号間の位相変化φは、 φ＝４πＺ（ｃｏｓθ1 −ｃｏｓ（θ1 ＋Δθ））／λ …（１） と表される（λはレーザー光の波長）。The phase change φ between the two signals when the measurement surface of the sample 9 is displaced by the height Z is expressed as follows: φ = 4πZ (cos θ 1 −cos (θ 1 + Δθ)) / λ (1) (Λ is the wavelength of the laser beam).
【００２５】なお、図２における試料９の測定面の光束
照射位置には、回折光を２次元分布させる回折格子が位
置合わせマークＭとして配置されているが、高さ検出に
必要な光束は正反射光のみなので、高さ検出のみの場合
にはマークＭは不要である。A diffraction grating for two-dimensionally distributing the diffracted light is arranged as an alignment mark M at the light beam irradiation position on the measurement surface of the sample 9 in FIG. 2, but the light beam required for height detection is positive. Since only the reflected light is used, the mark M is not required in the case of only the height detection.
【００２６】図３は、上式（１）で求められる位相変化
特性を示している。式（１）から分かるように、（ｃｏ
ｓθ1 −ｃｏｓ（θ1 ＋Δθ））／λの値を適当に設定
することにより、任意のＺの測定範囲で位相差が２π変
化するように調整することができる。具体的には入射角
度差Δθを調整することにより、Ｚの測定範囲を変化で
きる。よって、試料９の測定面に入射する光束５、８
と、入射角度が試料９の測定面の法線方向に異なる光束
７の法線方向の入射角度差Δθを調整する入射角度変更
機構を設ければ、高さＺの測定範囲を自由に設定でき
る。FIG. 3 shows the phase change characteristic obtained by the above equation (1). As can be seen from equation (1), (co
By appropriately setting the value of sθ 1 −cos (θ 1 + Δθ)) / λ, it is possible to adjust so that the phase difference changes by 2π in an arbitrary Z measurement range. Specifically, the Z measurement range can be changed by adjusting the incident angle difference Δθ. Therefore, the light fluxes 5 and 8 incident on the measurement surface of the sample 9
And the incident angle changing mechanism for adjusting the incident angle difference Δθ in the normal direction of the light beam 7 whose incident angle is different from the normal direction of the measurement surface of the sample 9, the measurement range of the height Z can be set freely. .
【００２７】また、位相差信号は基準信号、測定信号共
に試料９の表面に入射した光を用いて得ているので、試
料９の表面にレジストが塗布されるなどして表面状態が
変化した場合でも、この変化による光路長変化はどちら
の信号にも同じだけ影響する。従って、表面状態の影響
を受けることなく試料９の測定面の高さの変化のみを検
出することができる。Further, since the phase difference signal is obtained by using light incident on the surface of the sample 9 for both the reference signal and the measurement signal, when the surface state changes due to the application of a resist on the surface of the sample 9 or the like. However, the optical path length change due to this change affects both signals equally. Therefore, only the change in the height of the measurement surface of the sample 9 can be detected without being affected by the surface condition.
【００２８】一方、試料９の測定面と平行な方向の位置
検出を行うためには、測定面上の光束照射位置に図２に
示したような回折格子（マークＭ）を設け、この格子を
利用して変位を検出する。On the other hand, in order to detect the position of the sample 9 in the direction parallel to the measurement surface, a diffraction grating (mark M) as shown in FIG. Utilize to detect displacement.
【００２９】図４は、上記格子によって得られる回折光
分布を示すもので、図２における矢印１７の方向から観
察した状態を示している。図２中の座標系に基づき、
Ｘ，Ｙ方向の回折格子のピッチをＰx ，Ｐy とする。そ
して、光束１０、１１のＸ方向とＹ方向のｎ次の回折角
をそれぞれθx ，θy とすれば、 ｓｉｎθx ＝±λ／Ｐx …（２） ｓｉｎθ1 −ｓｉｎθy ＝±λ／Ｐy …（３） と表される。ここで、Ｘ方向の入射角をα（≠θx ）と
設定すれば、互いの反射回折光（正反射光を含む）は重
ならず、独立に取り込むことが可能になる。得られた回
折光の内、１次の回折光に注目する。Ｘ，Ｙ方向のマー
クＭの変位をそれぞれΔｘ，Δｙとすれば、Ｘ，Ｙ方向
変位に対する回折光の位相変化φx ，φyはそれぞれ、 φx ＝２πΔｘ／Ｐx …（４） φy ＝２πΔｙ／Ｐy …（５） と表される。また、高さＺが変化することによっても位
相が変化する（φz ）。FIG. 4 shows the distribution of diffracted light obtained by the grating, and shows a state observed from the direction of arrow 17 in FIG. Based on the coordinate system in FIG.
X, the pitch of the diffraction grating in the Y-direction P x, and P y. Then, n order diffraction angle in the X direction and the Y direction of the light beam 10, 11 respectively theta x, theta if y, sinθ x = ± λ / P x ... (2) sinθ 1 -sinθ y = ± λ / P y ... (3) Here, if the incident angle in the X direction is set to α (≠ θ x ), the reflected and diffracted light (including the specularly reflected light) does not overlap with each other and can be taken independently. Attention is paid to the first-order diffracted light among the obtained diffracted lights. Assuming that the displacement of the mark M in the X and Y directions is Δx and Δy, respectively, the phase changes φ x and φ y of the diffracted light with respect to the displacement in the X and Y directions are respectively φ x = 2πΔx / P x (4) φ y = 2πΔy / P y (5) Further, the phase also changes due to the change in the height Z (φ z ).
【００３０】例えば、Ｘ方向に−１次、Ｙ方向に１次の
回折光２１について、マークＭの変位に比例した位相変
化φ（−１，１）は、 φ（−１，１）＝φx ＋φy ＋φz ＝−２πΔｘ／Ｐx ＋２πΔｙ／Ｐy ＋φz …（６） の様に表される。この回折光は周波数ｆ2 で変調されて
いるので、位相変化を便宜上、ｆ2 （−ｘ，ｙ，ｚ）と
表す。例えば、この回折光２１とｆ1 ´（ｚ）で表され
る回折光１０とを重ね合わせ、うなりの信号を生成する
と、回折光１０、２１共に、Ｚの変化に対する位相変化
φz が等しいため、マークＭの変位による位相変化φb
は、 φb ＝φx ＋φy ＝−２πΔｘ／Ｐx ＋２πΔｙ／Ｐy …（７） となり、Δｘ，Δｙのみの関数となる。しかし、このま
まではＸ，Ｙ方向どちらに変位しても位相が変化し、変
位信号として適当でない。そこで、回折光１０と２１を
重ね合わせることにより生じるうなりの信号に加えて、
回折光１１と２０を重ね合わせることにより生じるうな
りの信号を生成する。For example, the phase change φ (−1, 1) proportional to the displacement of the mark M for the −1st-order diffracted light 21 in the X direction and the first-order diffracted light in the Y direction is as follows: φ (−1, 1) = φ is expressed as x + φ y + φ z = -2πΔx / P x + 2πΔy / P y + φ z ... (6). This diffracted light is modulated at a frequency f 2, it represents the phase change for convenience, f 2 (-x, y, z) and. For example, when the diffracted light 21 and the diffracted light 10 represented by f 1 ′ (z) are superimposed to generate a beat signal, both of the diffracted lights 10 and 21 have the same phase change φ z with respect to the change in Z. , Phase change φ b due to displacement of mark M
Is, φ b = φ x + φ y = -2πΔx / P x + 2πΔy / P y ... (7) becomes, [Delta] x, is a function of Δy only. However, in this state, the phase changes regardless of displacement in either the X or Y direction, and is not suitable as a displacement signal. Therefore, in addition to the beat signal generated by superimposing the diffracted lights 10 and 21,
A beat signal generated by superimposing the diffracted lights 11 and 20 is generated.
【００３１】即ち、図５に示すように、回折光１０と２
１をハーフミラー１３によって重ね合わせてセンサ１６
に供給すると共に、回折光１１と２０をハーフミラー１
４によって重ね合わせてセンサ１７に供給し、これらセ
ンサ１６、１７の出力信号を位相計１８に供給して変位
信号を生成する。センサ１６から出力されるうなりの信
号２２の位相φ1 とセンサ１７から出力されるうなりの
信号２３の位相φ2 の位相差Δφは、 Δφ＝φ1 −φ2 ＝４πΔｙ／Ｐy …（８） となり、位相計１８によってＹ方向の変位のみを検出で
きることになる。That is, as shown in FIG.
1 are overlapped by the half mirror 13 and the sensor 16
And diffracted light beams 11 and 20 into half mirror 1
Then, the signals are superimposed by 4 and supplied to a sensor 17, and the output signals of these sensors 16 and 17 are supplied to a phase meter 18 to generate a displacement signal. The phase difference Δφ between the phase φ 1 of the beat signal 22 output from the sensor 16 and the phase φ 2 of the beat signal 23 output from the sensor 17 is Δφ = φ 1 −φ 2 = 4πΔy / P y (8 ), And only the displacement in the Y direction can be detected by the phase meter 18.
【００３２】上記と同様に図６に示すような組み合わせ
で回折光を合成し、センサ１６、１７、２４、２５、２
６でうなりの信号を取り出し、位相計１８、２７、２８
にて位相差を検出することによりＸ，Ｙ，Ｚの変位をそ
れぞれ独立に測定することが可能となる。即ち、回折光
ｆ2 （−ｘ，ｙ，ｚ）の光束２１と回折光ｆ1 （ｚ）の
光束１２をビームスプリッタ（ハーフミラー）３０で分
けた光束とを合成部３１で重ね合わせ、波動の干渉によ
り生ずるうなりをセンサ１６で測定する。回折光ｆ2
（ｚ）の光束１１と回折光ｆ1 （ｚ）の光束１２とを合
成部３２で重ね合わせ、波動の干渉により生ずるうなり
をセンサ２５で測定する。また、回折光ｆ2 （ｘ，ｙ，
ｚ）の光束３３と回折光ｆ1 （−ｘ，ｙ，ｚ）の光束３
４とを合成部３５で重ね合わせ、波動の干渉により生ず
るうなりをセンサ２４で測定する。回折光ｆ1 ´（ｚ）
の光束１０と回折光ｆ2 （ｚ）の光束１１をハーフミラ
ー３６で分けた光束とを合成部３７で重ね合わせ、波動
の干渉により生ずるうなりをセンサ２６で測定する。更
に、回折光ｆ1 （ｘ，ｙ，ｚ）の光束２０と回折光ｆ2
（ｚ）の光束１１をハーフミラー３８で分けた光束とを
合成部３９で重ね合わせ、波動の干渉により生ずるうな
りをセンサ１７で測定する。そして、位相計２７によっ
て上記センサ２５から出力されるうなりの信号と上記セ
ンサ２４から出力されるうなりの信号の位相差を測定す
ると、Ｘ方向の変位信号（−２ｘ）が得られる。また、
位相計１８によって上記センサ１６から出力されるうな
りの信号と上記センサ１７から出力されるうなりの信号
の位相差を測定すると、Ｙ方向の変位信号（−２ｙ）が
得られる。同様に、位相計２８によって上記センサ２６
から出力されるうなりの信号と上記センサ２５から出力
されるうなりの信号の位相差を測定すると、Ｚ方向の変
位信号（Δｚ）が得られる。In the same manner as described above, the diffracted lights are combined in a combination as shown in FIG. 6 and the sensors 16, 17, 24, 25, 2
The beat signal is extracted at 6 and the phase meters 18, 27, 28
By detecting the phase difference at, the displacements of X, Y and Z can be measured independently of each other. That is, the light beam 21 of the diffracted light f 2 (−x, y, z) and the light beam 12 obtained by splitting the light beam 12 of the diffracted light f 1 (z) by the beam splitter (half mirror) 30 are superimposed by the combining unit 31, and the wave The beat generated by the interference of the above is measured by the sensor 16. Diffracted light f 2
The luminous flux 11 of (z) and the luminous flux 12 of the diffracted light f 1 (z) are superposed by the combining unit 32, and the beat generated by the interference of the wave is measured by the sensor 25. Also, the diffracted light f 2 (x, y,
z) light beam 33 and diffracted light beam f 1 (−x, y, z) light beam 3
4 is superimposed by the synthesizing unit 35, and the beat generated by the interference of the wave is measured by the sensor 24. Diffracted light f 1 ′ (z)
The light beam 10 and the light beam 11 obtained by dividing the light beam 11 of the diffracted light f 2 (z) by the half mirror 36 are overlapped by the combining unit 37, and the beat generated by the interference of the wave is measured by the sensor 26. Further, the light flux 20 of the diffracted light f 1 (x, y, z) and the diffracted light f 2
The luminous flux 11 of (z) is superimposed on the luminous flux divided by the half mirror 38 in the synthesizing unit 39, and the beat generated by the interference of the wave is measured by the sensor 17. When the phase difference between the beat signal output from the sensor 25 and the beat signal output from the sensor 24 is measured by the phase meter 27, a displacement signal (−2x) in the X direction is obtained. Also,
When the phase difference between the beat signal output from the sensor 16 and the beat signal output from the sensor 17 is measured by the phase meter 18, a displacement signal (-2y) in the Y direction is obtained. Similarly, the sensor 26
When the phase difference between the beat signal output from the sensor 25 and the beat signal output from the sensor 25 is measured, a displacement signal (Δz) in the Z direction is obtained.
【００３３】このような構成によれば、Ｘ，Ｙ，Ｚの変
位をそれぞれ独立に測定することができる。よって、電
子ビーム描画装置やステッパにおいて、簡単な構造でス
テージに載置された試料の測定面の位置測定やステージ
の位置検出を行うことができ、しかも電子ビームによる
レジストへのダメージやビームドリフトの影響のない高
精度な試料面位置測定装置及び測定方法が得られる。According to such a configuration, displacements of X, Y and Z can be measured independently. Therefore, the position of the measurement surface of the sample placed on the stage and the position of the stage can be measured with a simple structure in an electron beam writing apparatus or a stepper, and furthermore, damage to the resist and beam drift due to the electron beam can be performed. A highly accurate sample surface position measuring device and measuring method with no influence can be obtained.
【００３４】図７は、本発明の第４の実施の形態に係る
試料面位置測定装置の概略構成を示すブロック図であ
る。光源１から出射されたレーザー光は、ビームスプリ
ッタ２で第一の光路と第二の光路とに分けられ、音響光
学変調素子（ＡＯＭ）３、４にそれぞれ供給されて微小
量異なる周波数ｆ1 ，ｆ2 で変調される。上記ＡＯＭ
３、４から出射された光束はそれぞれ、折り返しミラー
やレンズ等の光学素子２９を介して試料９の測定面に照
射される。試料９の測定面で反射された光束はハーフミ
ラー１３で重ね合わされ、波動の干渉により生じるうな
りがセンサ１６で測定される。そして、上記センサ１６
によるうなりの信号と上記ＡＯＭ３、４の駆動電気信号
とが位相計１８に入力され、変位信号を得るようになっ
ている。FIG. 7 is a block diagram showing a schematic configuration of a sample surface position measuring apparatus according to a fourth embodiment of the present invention. The laser light emitted from the light source 1 is split by a beam splitter 2 into a first optical path and a second optical path, and supplied to acousto-optic modulators (AOMs) 3 and 4, respectively, so that the frequencies f 1 and f It is modulated at f 2. AOM above
The light beams emitted from 3 and 4 irradiate the measurement surface of the sample 9 via optical elements 29 such as folding mirrors and lenses. The luminous flux reflected by the measurement surface of the sample 9 is superimposed on the half mirror 13, and the beat generated by the interference of the wave is measured by the sensor 16. Then, the sensor 16
The beating signal and the driving electric signals of the AOMs 3 and 4 are input to the phase meter 18 to obtain a displacement signal.
【００３５】この第４の実施の形態では、出射光学系側
で周波数ｆ1 ，ｆ2 の干渉光束を生成せずに、ＡＯＭ
３、４の駆動電気信号を取り出して基準信号として位相
計１８に入力し、変位信号を得るようにしている。この
ような構成並びに方法であっても上述した各実施の形態
と同様な位置測定が行える。In the fourth embodiment, the output optical system does not generate the interference light beams of the frequencies f 1 and f 2 , and the AOM
The drive electric signals 3 and 4 are extracted and input to the phase meter 18 as reference signals to obtain displacement signals. Even with such a configuration and method, position measurement similar to that of each of the above-described embodiments can be performed.
【００３６】図８は、本発明の第５の実施の形態に係る
試料面位置測定装置の概略構成を示すブロック図であ
る。この第５の実施の形態にあっては、入射光学系側で
ハーフミラー４０、４１を用いて周波数ｆ1 ，ｆ2 の光
を干渉させ、これを測定することにより基準信号として
いる。そして、この基準信号とセンサ１６で検出したう
なりの信号とを位相計１８に入力して変位信号を得るよ
うにしている。このような構成並びに方法でも前述した
各実施の形態と同様な作用効果が得られる。FIG. 8 is a block diagram showing a schematic configuration of a sample surface position measuring apparatus according to a fifth embodiment of the present invention. In the fifth embodiment, light having frequencies f 1 and f 2 is caused to interfere with each other by using the half mirrors 40 and 41 on the incident optical system side, and the interference is measured to obtain a reference signal. Then, the reference signal and the beat signal detected by the sensor 16 are input to the phase meter 18 to obtain a displacement signal. With such a configuration and method, the same operation and effect as those of the above-described embodiments can be obtained.
【００３７】なお、この発明は上述した第１ないし第５
の実施の形態に限定されるものではなく、要旨を逸脱し
ない範囲で種々変形して実施することが可能である。例
えば、図１、７、８で示した実施の形態の場合、測定範
囲や光学系の設置角度の選定によっては互いの光束の分
離角度が小さく、２光束が完全に分離し難いことが考え
られる。このような場合には、入射光側の片側の光束に
偏光板を挿入し、一方の光束を他方の光束と偏光方向を
変えておくと良い。そして、反射光側で偏光ビームスプ
リッタによって２光束を分離し、再度偏光板を用いて偏
光方向を一致させ、再度重ね合わせる。ここでの偏光と
は、例えばＰ波、Ｓ波のように偏光するような場合であ
って、このような偏光を利用した分離方法によって１度
以下の分離角度でも容易に互いの光束の分離や重ね合わ
せが可能となる。The present invention is not limited to the first to fifth embodiments.
The present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention. For example, in the case of the embodiments shown in FIGS. 1, 7, and 8, it is conceivable that the separation angle of the light beams is small depending on the selection of the measurement range and the installation angle of the optical system, and it is difficult to completely separate the two light beams. . In such a case, it is preferable to insert a polarizing plate into the light beam on one side on the incident light side and change the polarization direction of one light beam from the other light beam. Then, the two light beams are separated by the polarizing beam splitter on the reflected light side, the polarization directions are matched again by using a polarizing plate, and the light beams are superposed again. The polarization here is a case where the light is polarized like a P-wave or an S-wave, for example, and the separation method using such a polarization easily separates the light beams even at a separation angle of 1 degree or less. Superposition becomes possible.
【００３８】また、上述した各実施の形態では、電子ビ
ーム描画装置やステッパに適用する場合を例にとって説
明したが、本発明の試料面位置検出装置及び測定方法
は、これらの装置への適用に限定されるものではないの
は勿論であり、試料の測定面の位置を非接触で高精度に
測定する必要がある装置であれば、いずれにも適用可能
である。In each of the embodiments described above, the case where the present invention is applied to an electron beam writing apparatus or a stepper has been described as an example. However, the sample surface position detecting apparatus and the measuring method of the present invention are applicable to these apparatuses. It is needless to say that the present invention is not limited thereto, and the present invention can be applied to any device that needs to measure the position of the measurement surface of the sample in a non-contact manner with high accuracy.
【００３９】[0039]
【発明の効果】上記のような構成並びに方法によれば、
光ヘテロダインを採用した位相測定のため、試料面から
の反射光量の変化に依存しない位置測定が可能になる。
また、光源にレーザー光を採用しているため、チャージ
アップによるドリフトを生じず、レジストに対するダメ
ージもなく安定した信号を得ることが可能となる。しか
も、本構成の光学系により、試料面の位置を高さ及び並
進方向に検出することができるので、装置構成を複雑に
することなく、高精度の位置検出が可能となる。According to the above configuration and method,
Since the phase measurement employs optical heterodyne, position measurement independent of a change in the amount of reflected light from the sample surface can be performed.
In addition, since laser light is used as the light source, drift due to charge-up does not occur, and a stable signal can be obtained without damage to the resist. Moreover, the position of the sample surface can be detected in the height and the translation direction by the optical system of the present configuration, so that highly accurate position detection can be performed without complicating the device configuration.
【００４０】従って、本発明によれば、簡単な構造で試
料面の位置測定を行うことができ、電子ビームによるレ
ジストへのダメージやビームドリフトの影響のない高精
度な試料面位置測定装置及び測定方法が得られる。Therefore, according to the present invention, the position of a sample surface can be measured with a simple structure, and a highly accurate sample surface position measuring device and a measurement method can be used which are free from damage to a resist by an electron beam and the influence of beam drift. A method is obtained.
【図１】本発明の第１の実施の形態に係る試料面位置測
定装置及び測定方法について説明するためのもので、
（ａ）図は出射光側の概略構成図、（ｂ）図は試料面の
高さを測定する場合の受光側の概略構成図。FIG. 1 is a view for explaining a sample surface position measuring device and a measuring method according to a first embodiment of the present invention,
(A) is a schematic configuration diagram on the outgoing light side, and (b) is a schematic configuration diagram on the light receiving side when measuring the height of the sample surface.
【図２】図１における試料の測定面への入射光と反射光
の関係を詳細に示す斜視図。FIG. 2 is a perspective view showing in detail the relationship between incident light and reflected light on a measurement surface of the sample in FIG.
【図３】試料面の高さ測定により得られる位相変化特性
を示す図。FIG. 3 is a diagram showing a phase change characteristic obtained by measuring the height of a sample surface.
【図４】図１及び図２に示した試料面位置測定装置で得
られた回折光分布を示す図。FIG. 4 is a diagram showing a diffracted light distribution obtained by the sample surface position measuring device shown in FIGS. 1 and 2;
【図５】本発明の第２の実施の形態に係る試料面位置測
定装置及び測定方法について説明するためのもので、Ｙ
方向の変位を検出する場合の受光側の概略構成図。FIG. 5 is a view for explaining a sample surface position measuring apparatus and a measuring method according to a second embodiment of the present invention.
FIG. 3 is a schematic configuration diagram of a light receiving side when detecting displacement in a direction.
【図６】本発明の第３の実施の形態に係る試料面位置測
定装置及び測定方法について説明するためのもので、
Ｘ，Ｙ，Ｚ３方向の変位を検出する場合の受光側の概略
構成図。FIG. 6 is a view for explaining a sample surface position measuring device and a measuring method according to a third embodiment of the present invention;
FIG. 3 is a schematic configuration diagram of a light receiving side when detecting displacements in X, Y, and Z3 directions.
【図７】本発明の第４の実施の形態に係る試料面位置測
定装置及び測定方法について説明するための概略構成
図。FIG. 7 is a schematic configuration diagram for explaining a sample surface position measuring device and a measuring method according to a fourth embodiment of the present invention.
【図８】本発明の第５の実施の形態に係る試料面位置測
定装置及び測定方法について説明するための概略構成
図。FIG. 8 is a schematic configuration diagram for explaining a sample surface position measuring device and a measuring method according to a fifth embodiment of the present invention.
１…光源、２，６，１３，１４，１５…ビームスプリッ
タ（ハーフミラー）、３，４…音響光学変調素子（ＡＯ
Ｍ）、５，７，８…入射光束、９…試料、１０，１１，
１２…出射光束、１６，１７，２４，２５，２６…セン
サ、１８，２７，２８…位相計、２０，２１…回折光、
２２，２３…うなりの信号、２９…光学素子。DESCRIPTION OF SYMBOLS 1 ... Light source, 2, 6, 13, 14, 15 ... Beam splitter (half mirror), 3, 4 ... Acousto-optic modulation element (AO
M), 5, 7, 8 ... incident luminous flux, 9 ... sample, 10, 11,
12, outgoing light flux, 16, 17, 24, 25, 26 ... sensor, 18, 27, 28 ... phase meter, 20, 21 ... diffracted light,
22, 23: beat signal, 29: optical element.
Claims (4)
くとも２本照射する手段と、前記試料の測定面で反射ま
たは回折した光を検出器に導く手段と、検出器に導かれ
た２光束に含まれる周波数の異なる光の波動の干渉によ
り生じるうなりの位相を検出する手段とを具備し、前記
試料の測定面における法線方向の位置または前記試料の
測定面内で互いに直交する２方向の変位を検出すること
を特徴とする試料面位置測定装置。1. A means for irradiating at least two coherent lights on a measurement surface of a sample, a means for guiding light reflected or diffracted on the measurement surface of the sample to a detector, and a light guided to the detector. Means for detecting a phase of a beat generated by interference of waves of light having different frequencies included in the two light beams, wherein the position of the sample in the normal direction on the measurement surface or the two orthogonal to each other in the measurement surface of the sample are provided. A sample surface position measuring device for detecting a displacement in a direction.
格子が形成された試料に、測定面と平行な変位検出方向
のうちの一方と試料の測定面における法線方向とが成す
面に対し、互いに異なる方向から少なくとも２本の光束
を入射させるとともに、前記２本の光束に対し試料の測
定面の法線方向に異なる角度で少なくとも１本の光束を
入射させる試料面照射手段と、前記試料の測定面上に設
けられた回折格子から生じる反射回折光のうち任意の２
光束を組み合わせて互いに干渉するように重ね合わせる
光学手段と、前記２光束の波動の干渉により生じるうな
りと等しい周波数を有する基準信号と前記２光束の波動
の干渉により生じるうなりの信号との位相差を測定する
測定手段とを具備し、前記試料の測定面の法線方向の位
置及び試料の測定面内で互いに直交する２方向の変位を
検出することを特徴とする試料面位置測定装置。2. A sample in which a diffraction grating for two-dimensionally distributing diffracted light is formed on a measurement surface is provided on a surface formed by one of displacement detection directions parallel to the measurement surface and a normal direction on the measurement surface of the sample. On the other hand, a sample surface irradiating means for causing at least two light beams to be incident from directions different from each other, and causing at least one light beam to be incident on the two light beams at a different angle in a direction normal to a measurement surface of the sample, Any two of the reflected diffraction light generated from the diffraction grating provided on the measurement surface of the sample
Optical means for combining light beams and superimposing them so as to interfere with each other; and a phase difference between a reference signal having a frequency equal to the beat generated by the interference of the waves of the two light beams and a beat signal generated by the interference of the waves of the two light beams. A sample surface position measuring device, comprising: a measuring means for measuring, and detecting a position in a normal direction of a measurement surface of the sample and a displacement in two directions orthogonal to each other within the measurement surface of the sample.
くとも２本照射する手段と、前記試料の測定面で反射ま
たは回折した光を検出器に導く手段と、検出器に導かれ
た２光束に含まれる周波数の異なる光の波動の干渉によ
り生じるうなりの位相を検出する手段とを具備し、荷電
粒子ビームを用いたパターン描画装置内に設けられた試
料を移動させるためのステージの位置、またはこのステ
ージに載置された試料の測定面の位置を検出することを
特徴とする試料面位置測定装置。3. A means for irradiating at least two coherent lights on a measurement surface of a sample, a means for guiding light reflected or diffracted on the measurement surface of the sample to a detector, and a light guided to the detector. Means for detecting a beat phase caused by interference between waves of light having different frequencies contained in the two light fluxes, and a position of a stage for moving a sample provided in a pattern drawing apparatus using a charged particle beam. Or a sample surface position measuring device for detecting a position of a measurement surface of a sample placed on the stage.
とも２本の可干渉性のある光ビームを生成する第１のス
テップと、前記少なくとも２本の光ビームを試料の測定
面に照射する第２のステップと、前記試料の測定面で反
射または回折した少なくとも２本の光ビームを受光する
第３のステップと、前記第３のステップで受光した光ビ
ームの光学的演算を行って選択的に重ね合わせる第４の
ステップと、前記第４のステップで光学的演算を施した
光信号を電気信号に変換する第５のステップと、前記第
５のステップで変換された電気信号と基準信号との位相
差を演算する第６のステップとを具備し、前記試料の測
定面における法線方向の位置または前記試料の測定面内
で互いに直交する２方向の変位を検出することを特徴と
する試料面位置測定方法。4. A first step of generating at least two coherent light beams modulated by minute amounts of different frequencies, and a second step of irradiating the at least two light beams to a measurement surface of a sample. And a third step of receiving at least two light beams reflected or diffracted on the measurement surface of the sample, and selectively overlapping by performing an optical operation on the light beams received in the third step. A fourth step of combining, a fifth step of converting the optical signal subjected to the optical operation in the fourth step into an electric signal, and a position of the electric signal and the reference signal converted in the fifth step. A step of calculating a phase difference, wherein a position in a normal direction on the measurement surface of the sample or a displacement in two directions orthogonal to each other within the measurement surface of the sample is detected. Measurement Method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18355496A JP3364382B2 (en) | 1996-07-12 | 1996-07-12 | Sample surface position measuring device and measuring method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18355496A JP3364382B2 (en) | 1996-07-12 | 1996-07-12 | Sample surface position measuring device and measuring method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1026513A true JPH1026513A (en) | 1998-01-27 |
| JP3364382B2 JP3364382B2 (en) | 2003-01-08 |
Family
ID=16137844
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18355496A Expired - Lifetime JP3364382B2 (en) | 1996-07-12 | 1996-07-12 | Sample surface position measuring device and measuring method |
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| Country | Link |
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