JP3364382B2 - Sample surface position measuring device and measuring method - Google Patents
Sample surface position measuring device and measuring methodInfo
- Publication number
- JP3364382B2 JP3364382B2 JP18355496A JP18355496A JP3364382B2 JP 3364382 B2 JP3364382 B2 JP 3364382B2 JP 18355496 A JP18355496 A JP 18355496A JP 18355496 A JP18355496 A JP 18355496A JP 3364382 B2 JP3364382 B2 JP 3364382B2
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- Japan
- Prior art keywords
- light
- sample
- measurement surface
- measurement
- diffracted
- 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.)
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- Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
- Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
- Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
- Length Measuring Devices By Optical Means (AREA)
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。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample surface position measuring apparatus and a measuring method for measuring the 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, circuit line widths required for semiconductor devices have become narrower with higher integration of LSIs. These semiconductor devices are created by aligning dozens of original image patterns (reticles or masks) on which desired circuit patterns are formed with high precision on an exposure area on a wafer and then repeating transfer. The apparatus used for this transfer is a reduction projection exposure apparatus having a highly accurate optical system, and the wafer side is fixed on a highly accurate XY stage so that the entire surface of the wafer on the transferred side can be exposed. . The transfer device is also called a stepper because the wafer is step-and-repeat with respect to the optical system.
【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。Conventionally, the reduction ratio of the stepper has been one-fifth. It has been said so far that patterns of 1 μm or less cannot be resolved due to the wavelength limit of light, but with the improvement of the optical system / illumination system and the emergence of phase shift masks that adjust the phase of light on the reticle, sub-μm patterns have been developed. Has been resolved. As the resolution is improved, the depth of focus of the reduction lens is reduced, and a stricter value is required for the accuracy of transferring the original image pattern onto the pattern previously formed on the wafer. There is a demand for highly accurate detection of the position of in the sample surface direction and the focus direction.
【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。The original image pattern is drawn on a glass substrate finished with high accuracy, and is subjected to a resist process or the like to form Cr.
It is formed as a pattern of (chrome). Usually, a glass substrate having Cr deposited on one side and a resist uniformly applied is used. An energy beam using a focused electron or laser of a pattern drawing device 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
By using the resist that has been altered by the irradiation of the energy beam, the etching of Cr is suppressed depending on the location,
Obtain the desired Cr pattern. Further, at this time, since the focused beam spots are connected to form one pattern, 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。Further, as the resolution is improved, 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 thickness of the substrate, or the refractive index is different. A so-called phase shift mask has been proposed in which the material is partially changed by a method such as adding a material (JP-A-6-222190, etc.). In producing the phase shift mask, a resist is applied again to the glass substrate on which the Cr pattern is formed in advance, a material for partially changing the phase of the light transmitting portion is added, and then an unnecessary portion is etched. ,
Alternatively, a method in which a glass substrate of a specific light transmitting portion is dug in the thickness direction and the optical path length is selectively changed is adopted. Therefore, it is necessary to expose the resist at a predetermined position with high accuracy in the pattern drawing device.
【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 the pattern position, a method has been proposed in which an electron beam drawing apparatus scans an alignment mark provided on a substrate with a drawing beam, captures backscattered electrons obtained by the sensor, and performs signal processing. (JP-A-58-223326, etc.). However, in this method, (a) the irradiation of the high acceleration beam damages the resist on the alignment mark, (b) the damaged resist deteriorates the vacuum atmosphere,
(C) Since the mark is measured through the resist layer, there is a problem that the signal contrast is lowered. In order to avoid the problems (a) to (c), there is a method of removing the resist in the mark portion in advance, but there is a problem that a process for that is required and the process 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。Further, in order to measure the pattern position with high accuracy, it is necessary to stably reproduce the irradiation position of the electron beam regardless of the passage of time. However, in reality, when the electron beam is contaminated inside the lens barrel, drift occurs due to charge-up, and when the electron beam drifts, the measured value fluctuates. Therefore, prior to the detection of the alignment mark on the mask, the irradiation position of the beam 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 becomes 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 mark position measurement on the mask is an indirect measurement via the mark on the stage, when the measured value fluctuates,
There is a problem that it is not possible to distinguish whether the cause is 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。By the way, a method of providing a measuring optical system using a laser beam is known as a method for accurately measuring the position of the mark in an electron beam drawing apparatus or a stepper. However, for high precision measurement,
Since it is necessary to perform the measurement at the position where the electron beam or the exposure light is emitted, 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, in the conventional sample surface position measuring apparatus and measuring method, the structure for measuring the position of the sample surface becomes complicated and the processing becomes complicated, and the resist by the electron beam is used. There was a problem that the accuracy was lowered due to the damage to the beam and the influence of 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。The present invention has been made in order to solve the above-mentioned problems, and it is possible to measure the position of a sample surface with a simple structure, and it is possible to achieve high precision without damaging a resist by an electron beam or beam drift. An object is 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 technique of the prior application (Japanese Patent Application No. 3-82318), but a sample having a relatively simple structure and being sufficiently practical. A surface position measuring device and measuring method are realized.
【００１２】[0012]
【００１３】[0013]
【００１４】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
る方向から第１，第２の光束を入射させるとともに、前
記第１，第２の光束に対し試料の測定面の法線となす角
度が異なる第３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
射回折光のうち前記第１，第２の光束に対応する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、且つ
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
射回折光のうち前記第１，第３の光束に対応する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、前記第１，第３の光束に対応する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
信号と前記第１，第２の光束に対応する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。 The sample surface position measuring device of the present invention is arranged such that one of a displacement detection direction parallel to the measurement surface and the measurement surface of the sample is provided on the sample on which a diffraction grating for two-dimensionally distributing diffracted light is formed. with respect to a plane formed by the normal direction, it causes the incident first, second light flux from different directions, before
Note: The angle between the first and second luminous flux and the normal to the measurement surface of the sample
Sample surface irradiating means for injecting third light beams having different degrees ,
Two light beams corresponding to the first and second light beams of the reflected diffracted light generated from the diffraction grating provided on the measurement surface of the sample
A combination of superimposed so as to interfere with each other, and
Reaction generated from the diffraction grating provided on the measurement surface of the sample
Two light beams corresponding to the first and third light beams of the diffracted light
Optical means for combining and combining them so as to interfere with each other , a reference signal having a frequency equal to a beat generated by the interference of waves of two light fluxes corresponding to the first and third light fluxes, and the first and second light fluxes. Measuring means for measuring the phase difference from the beat signal generated by the interference of the wave motions of the two light fluxes corresponding to the above-mentioned two, which are orthogonal to each other in the position in the normal direction of the measurement surface of the sample and in the measurement surface of the sample. The feature is that the displacement in the direction is detected.
【００１５】上記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
から入射される第１，第２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。In the above-mentioned sample surface position measuring device, the first and the first incident beams are incident from different directions with respect to a plane formed by one of the displacement detection directions parallel to the measurement surface and the normal direction to the measurement surface of the sample . It is desirable that the second light flux is a mixture of waves having slightly different frequencies.
【００１６】また、上記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第１，第２の光束をそれ
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
入射させる第１，第２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第３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
ら入射する第１，第２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、“ｓｉｎ
θx ＝±λ／Ｐx ”、“ｓｉｎθ1 −ｓｉｎθy ＝±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。Further , in the above sample surface position measuring device,
It further comprises polarizing means for polarizing the first and second light beams incident on the measurement surface of the sample so as to have respectively different polarization directions or rotation directions, and after separating each reflected diffracted light by this polarization means, The first and second light beams which are guided to the optical means and overlap each other so as to interfere with each other , and the first and second light beams which are incident on the measurement surface of the sample, and the third light beam whose incident angle differs in the normal direction of the measurement surface of the sample. Further comprising incident angle changing means for adjusting the angle difference in the normal direction, to one of the displacement detection direction parallel to the measurement surface of the sample and the surface formed by the normal direction of the measurement surface of the sample, The first and second light beams entering from the symmetrical directions have wavelengths of λ, pitches of diffraction gratings in the X and Y directions of Px and Py, and n in the X and Y directions.
Assuming that the next diffraction angles are θx and θy respectively, “sin
θx = ± λ / Px ”,“ sin θ1 −sin θy = ± λ
/ Py "and the incident angle in the X direction is preferably set to α (≠ θx).
【００１７】また、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
ステージに、測定面と平行な変位検出方向のうちの一方
と前記測定面における法線方向とが成す面に対し、互い
に異なる方向から第１，第２の光束を入射させるととも
に、前記第１，第２の光束に対し前記測定面の法線とな
す角度が異なる第３の光束を入射させる試料面照射手段
と、前記測定面に設けられた回折格子から生じる反射回
折光のうち前記第１，第２の光束に対応する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、且つ前記
測定面に設けられた回折格子から生じる反射回折光のう
ち前記第１，第３の光束に対応する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
第１，第３の光束に対応する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第
１，第２の光束に対応する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、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前記ステージにおける
法線方向の位置及び前記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, the sample surface position measuring apparatus of the present invention, measurement
A diffraction grating that distributes diffracted light in a two-dimensional manner was formed on the fixed surface.
One of the displacement detection directions parallel to the measurement surface on the stage
With respect to the plane formed by
When the first and second light beams are made to enter from different directions,
In addition, the normal to the measurement surface is not applied to the first and second light fluxes.
Specimen surface irradiating means for injecting third light beams having different angles
And a reflection pattern generated from the diffraction grating provided on the measurement surface.
A set of two light beams corresponding to the first and second light beams
And overlap them so that they interfere with each other.
Reflected diffracted light generated by the diffraction grating provided on the measurement surface
A combination of two light fluxes corresponding to the first and third light fluxes
Optical means for overlapping so as to interfere with each other,
Due to the interference of the waves of the two light fluxes corresponding to the first and third light fluxes
A reference signal having a frequency equal to the resulting beat and the first
It is generated by the interference of the waves of the two light fluxes corresponding to the first and second light fluxes.
And a measuring means for measuring the phase difference from the signal of the whirling beat, provided in a pattern drawing apparatus using a charged particle beam.
In the stage for moving the scraped sample
Positions in the normal direction and two directions orthogonal to each other in the measurement plane
The feature is that the displacement in the direction is detected .
【００１８】更に、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可干渉性のある第１，第
２の光ビームを生成する第１のステップと、前記第１，
第２のビームの一方から第３の光ビームを生成する第２
のステップと、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、前記測定面と平行な変位検出
方向のうちの一方と、前記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前記第１，第２の
光ビームを照射するとともに、前記第１，第２の光ビー
ムに対して前記試料の測定面の法線と異なる角度で前記
第３の光ビームを照射する第３のステップと、前記試料
の測定面で反射または回折した前記第１乃至第３の光ビ
ームを受ける第４のステップと、前記第４のステップで
受けた前記第１，第３の光ビームの光学的演算を行って
選択的に重ね合わせるとともに、前記第１，第２の光ビ
ームの光学的演算を行って選択的に重ね合わせる第５の
ステップと、前記第５のステップで光学的演算を施した
光信号をそれぞれ第１，第２の電気信号に変換する第６
のステップと、前記第６のステップで変換された第１の
電気信号と第２の電気信号との位相差を演算する第７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
向の位置及び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, the sample surface position measuring method according to the present invention is such that the first and the first coherent signals which are modulated by a minute amount of different frequencies are used .
A first step of generating a second light beam ;
A second beam generating a third light beam from one of the second beams
And the diffraction that two-dimensionally distributes the diffracted light on the measurement surface
Displacement detection parallel to the measurement surface on a sample with a grid
One of the directions and the normal direction to the measurement surface
The first and second directions from different directions with respect to the surface to be formed.
The first and second light beams are emitted while irradiating a light beam.
At an angle different from the normal to the measurement surface of the sample
A third step of irradiating a third light beam; a fourth step of receiving the first to third light beams reflected or diffracted by the measurement surface of the sample; and a fourth step.
An optical operation of the received first and third light beams is performed to selectively superimpose them, and at the same time, the first and second light beams are
Sixth converting the fifth step of performing selective superimposed optical operations over beam, an optical signal subjected to optical calculation at the fifth step first respectively to a second electrical signal
And a seventh step of calculating a phase difference between the first electric signal and the second electric signal converted in the sixth step. It is characterized in that the position in the normal direction and the displacement in two directions orthogonal to each other in the measurement plane of the sample are detected.
【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 above-described structure and method, the two light beams having different angles which are specularly reflected by 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 in angle, the optical path is changed. 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. Further, a diffraction grating that two-dimensionally distributes the diffracted light is provided as an alignment mark on the measurement surface of the sample that emits the light flux, and one of the displacement detection directions parallel to the measurement surface of the sample and the normal direction of the sample surface are provided. When two measuring beams of the sample are displaced in the direction parallel to the measuring surface due to the difference of the diffraction angles, the two light beams emitted in the symmetric direction with respect to the plane formed by The phase changes. By measuring this amount, it is possible to measure displacement in two directions orthogonal to each other within 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。Since the above-described configuration and method employ the phase measurement employing the optical heterodyne, it is possible to perform the position measurement independent of the change in the amount of light reflected from the measurement surface of the sample. Further, since the laser light is used as the light source, it is possible to obtain a stable signal without causing a drift due to charge-up. Further, since the position of the sample surface can be detected in the height and the translational direction by the optical system having the above-mentioned configuration, 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。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 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. FIG. 1A is a schematic configuration diagram on a laser light irradiation side, and FIG. Is a schematic configuration diagram of the light receiving side when measuring the height of the measurement surface of the sample, and FIG. 2 is FIG.
It is a perspective view which shows in detail the relationship of the incident light and reflected light to the measurement surface of the sample in (b).
【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. Laser light having a strong coherence emitted from this light source 1 is passed through a beam splitter (half mirror) 2 to a first optical path and a second optical path. It is divided into the optical path of. The divided light fluxes are modulated by acousto-optic modulators (AOMs) 3 and 4 at frequencies f 1 and f 2 which differ by a small amount. AO
The light beam 5 emitted from M3 is further divided by a beam splitter 6 to obtain a third light beam 7. These three light beams 5, 7 and 8 are passed through a folding mirror and a lens (not shown), and two light beams 5 and 8 therein 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 obliquely irradiated with the light beams 5 and 8 and the incident angle difference Δθ (see FIG. 2). In addition, the luminous flux 5 and 7,
8 is incident at an angle α from a direction that is 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 regular reflection lights 12 and 10 of the light beams 7 and 8 are separated with an emission angle difference Δθ in the height direction as illustrated. On the other hand, the specularly reflected lights 11 and 10 of the light beams 5 and 8 have the same emission angle in the height direction and the angle difference 2 in the direction parallel to the measurement surface of the sample 9.
It becomes separated with 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. 1 (b), the two light fluxes 10, 11 and 10, 12 reflected by the measurement surface of the sample 9 are superposed on each other by using half mirrors 13, 14, 15, respectively, to generate a wave motion. The sensor 16 detects the beat generated by the interference.
It becomes possible to measure with (this becomes a height detection signal) and the sensor 17 (this becomes a 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 φ = 4πZ (cos θ 1 -cos (θ 1 + Δθ)) / λ (1) (Λ is the wavelength of the laser light).
【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 luminous flux irradiation position on the measurement surface of the sample 9 in FIG. 2, but the luminous flux necessary for height detection is positive. Since only the reflected light is used, the mark M is unnecessary when only height detection is performed.
【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 properly setting the value of sθ 1 -cos (θ 1 + Δθ)) / λ, the phase difference can be adjusted to change by 2π in the arbitrary Z measurement range. Specifically, the Z measurement range can be changed by adjusting the incident angle difference Δθ. Therefore, the light beams 5 and 8 incident on the measurement surface of the sample 9
And an incident angle changing mechanism for adjusting the incident angle difference Δθ in the normal direction of the light beam 7 having different incident angles in the normal direction of the measurement surface of the sample 9, the measurement range of the height Z can be freely set. .
【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 the light incident on the surface of the sample 9 for both the reference signal and the measurement signal, when the surface condition is changed by coating the surface of the sample 9 with a resist or the like. However, the change in optical path length due to this change affects both signals by the same amount. 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. 2 is provided at the luminous flux irradiation position on the measurement surface, and this grating is used. Use this 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 diffracted light distribution obtained by the above-mentioned grating, and shows the state observed from the direction of arrow 17 in FIG. Based on the coordinate system in Figure 2,
X, the pitch of the diffraction grating in the Y-direction P x, and P y. Then, if the nth-order diffraction angles of the light fluxes 10 and 11 in the X direction and the Y direction are θ x and θ y , respectively, sin θ x = ± λ / P x (2) sin θ 1 −sin θ y = ± λ / It is expressed as P y (3). Here, if the incident angle in the X direction is set to α (≠ θ x ), reflected diffracted lights (including specularly reflected lights) do not overlap with each other and can be independently captured. Of the obtained diffracted light, attention is paid to the first-order diffracted light. If 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 displacements in the X and Y directions are φ x = 2πΔx / P x (4) φ y = 2πΔy / P y (5) Also, the phase changes (φ z ) as the height Z changes.
【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 1st order in the Y direction is φ (−1,1) = φ x + φ y + φ z = −2πΔx / P x + 2πΔy / P y + φ z (6) Since this diffracted light is modulated with the frequency f 2 , the phase change is represented as f 2 (−x, y, z) for convenience. For example, when the diffracted light 21 and the diffracted light 10 represented by f 1 ′ (z) are overlapped to generate a beat signal, the diffracted lights 10 and 21 have the same phase change φ z with respect to the change in Z. , Phase change due to displacement of mark M φ b
Becomes φ b = φ x + φ y = −2πΔx / P x + 2πΔy / P y (7), which is a function of only Δx and Δy. However, if it is left as it is, the phase changes regardless of whether it is displaced in the X or Y direction, which is not suitable as a displacement signal. Therefore, in addition to the beat signal generated by overlapping the diffracted lights 10 and 21,
A beat signal generated by overlapping 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 is overlapped by the half mirror 13 and the sensor 16
And the diffracted lights 11 and 20 are supplied to the half mirror 1.
4, the signals are superposed and supplied to the sensor 17, and the output signals of the sensors 16 and 17 are supplied to the 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 ), The phase meter 18 can detect only the displacement in the Y direction.
【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。Similarly to the above, the diffracted lights are combined by the combination shown in FIG. 6, and the sensors 16, 17, 24, 25, 2 are combined.
The beat signal is taken out by 6 and the phase meters 18, 27, 28
By detecting the phase difference at, the X, Y, and Z displacements can be measured independently. That is, the light flux 21 of the diffracted light f 2 (−x, y, z) and the light flux 12 of the diffracted light f 1 (z) are separated by the beam splitter (half mirror) 30 and are combined by the combining unit 31 to generate the wave motion. The beat generated by the interference of the sensor 16 is measured by the sensor 16. Diffracted light f 2
The light flux 11 of (z) and the light flux 12 of the diffracted light f 1 (z) are superimposed on each other by the combining unit 32, and the beat generated by the interference of waves is measured by the sensor 25. Also, the diffracted light f 2 (x, y,
z) light flux 33 and diffracted light f 1 (−x, y, z) light flux 3
4 and 4 are superposed on each other by the synthesizing unit 35, and the beat generated by the interference of waves is measured by the sensor 24. Diffracted light f 1 ′ (z)
The light beam 10 and the light beam 11 of the diffracted light f 2 (z) are combined by the half mirror 36 at the combining unit 37, and the beat generated by the interference of the waves is measured by the sensor 26. Further, the light beam 20 of the diffracted light f 1 (x, y, z) and the diffracted light f 2
The light flux 11 of (z) and the light flux split by the half mirror 38 are superimposed on each other by the combining unit 39, and the beat generated by the interference of the waves 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 phase meter 28 causes the sensor 26 to
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。With this configuration, the X, Y and Z displacements can be measured independently. Therefore, in the electron beam drawing apparatus and the stepper, the position of the measurement surface of the sample placed on the stage and the position of the stage can be detected with a simple structure, and the damage to the resist and the beam drift due to the electron beam can be prevented. It is possible to obtain a highly accurate sample plane position measuring device and a measuring method that have no influence.
【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 the schematic arrangement of a sample surface position measuring apparatus according to the fourth embodiment of the present invention. The laser light emitted from the light source 1 is split into a first optical path and a second optical path by the beam splitter 2, and supplied to the acousto-optic modulators (AOMs) 3 and 4, respectively, and the frequencies f 1 and f 1 are slightly different from each other. It is modulated by f 2 . Above AOM
The luminous fluxes emitted from 3 and 4 are applied to the measurement surface of the sample 9 through the optical elements 29 such as the folding mirror and the lens. The light beams reflected by the measurement surface of the sample 9 are superposed by the half mirror 13, and the beat generated by the interference of the waves is measured by the sensor 16. Then, the sensor 16
The beat signal by and the electric signal for driving 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 AOM does not generate the interference light beams having the frequencies f 1 and f 2 on the side of the emission optical system.
The driving electric signals of 3 and 4 are taken out and input to the phase meter 18 as a reference signal to obtain a displacement signal. Even with such a configuration and method, the same position measurement as in 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 the schematic arrangement of a sample surface position measuring apparatus according to the fifth embodiment of the present invention. In the fifth embodiment, the half mirrors 40 and 41 are used on the incident optical system side to interfere lights of frequencies f 1 and f 2 and the light is used as 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. Even with such a configuration and method, the same operational effects as those of the above-described respective 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 based on the above-mentioned first to fifth aspects.
The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the scope of the invention. For example, in the case of the embodiment shown in FIGS. 1, 7, and 8, it is conceivable that the separation angle of the light beams from each other is small and it is difficult to completely separate the two light beams depending on the selection of the measurement range and the installation angle of the optical system. . In such a case, it is advisable to insert a polarizing plate into one light beam on the incident light side and change the polarization direction of one light beam from the other light beam. Then, on the reflected light side, the two light beams are separated by a polarization beam splitter, the polarizing directions are again made to coincide with each other by using a polarizing plate, and they are overlapped again. The polarization here is a case of polarization such as P-wave and S-wave, and the separation method utilizing such polarization makes it easy to separate light beams from each other even at a separation angle of 1 degree or less. Superposition is 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。Further, in each of the above-described embodiments, the case where the invention is applied to the electron beam drawing apparatus and the stepper has been described as an example, but the sample surface position detecting apparatus and the measuring method of the present invention can be applied to these apparatuses. It is needless to say that the present invention is not limited to this, and can be applied to any device as long as it is necessary 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-described structure and method,
Since the phase measurement adopts the optical heterodyne, the position measurement independent of the change in the amount of light reflected from the sample surface becomes possible.
Further, since laser light is used as the light source, drift due to charge-up does not occur, and it is possible to obtain a stable signal without damaging the resist. Moreover, since the position of the sample surface can be detected in the height and the translational direction by the optical system of this configuration, 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 the sample surface can be measured with a simple structure, and a highly accurate sample surface position measuring device and measurement without damaging the resist by the electron beam or the influence of the beam drift are provided. 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 apparatus and a measuring method according to a first embodiment of the present invention,
FIG. 6A is a schematic configuration diagram on the outgoing light side, and FIG. 6B 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 the 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 device 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 a 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,
The schematic block diagram of the light-receiving side in the case of detecting displacements in the 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。1 ... Light source, 2, 6, 13, 14, 15 ... Beam splitter (half mirror), 3, 4 ... Acousto-optic modulator (AO
M), 5, 7, 8 ... Incident light flux, 9 ... Sample, 10, 11,
12 ... Emitted light flux, 16, 17, 24, 25, 26 ... Sensor, 18, 27, 28 ... Phase meter, 20, 21 ... Diffracted light,
22, 23 ... beat signal, 29 ... optical element.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G01B 11/00 H01L 21/027 H01L 21/68 ─────────────────────────────────────────────────── ─── Continued Front Page (58) Fields surveyed (Int.Cl. 7 , DB name) G01B 11/00 H01L 21/027 H01L 21/68
Claims (3)
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第１，第２の光束を入
射させるとともに、前記第１，第２の光束に対し試料の
測定面の法線となす角度が異なる第３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前記第１，第２の
光束に対応する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、且つ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前記第１，第３の
光束に対応する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、前記第１，第３の光束に
対応する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第１，第２の光束に対
応する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。1. A sample on which a diffraction grating for two-dimensionally distributing diffracted light is formed on a measurement surface is formed on a surface formed by one of displacement detection directions parallel to the measurement surface and a normal direction to the measurement surface of the sample. On the other hand, the first and second light fluxes are made to enter from different directions, and the sample light is applied to the first and second light fluxes.
The first and second of the diffracted diffracted light generated from the sample surface irradiating means for injecting a third light beam having an angle different from the normal line of the measurement surface and the diffraction grating provided on the measurement surface of the sample .
By combining two light beams corresponding to the light flux superimposed to interfere with each other, it was and is provided on the measurement surface of the sample
Of the reflected diffracted light generated from the diffraction grating, the first and third
Two light fluxes corresponding to the light flux are combined and interfere with each other.
And the optical means for superimposing them on each other ,
A pair of a reference signal having a frequency equal to the beat generated by the interference of the waves of the corresponding two light fluxes and the first and second light fluxes.
Measuring means for measuring the phase difference from the beat signal generated by the interference of the waves of the two corresponding light beams, and the two directions orthogonal to each other in the normal position of the measurement surface of the sample and in the measurement surface of the sample. A device for measuring the position of a sample surface, which detects the displacement of the sample.
格子が形成されたステージに、測定面と平行な変位検出
方向のうちの一方と前記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第１，第２の光束を
入射させるとともに、前記第１，第２の光束に対し前記
測定面の法線となす角度が異なる第３の光束を入射させ
る試料面照射手段と、前記測定面に設けられた回折格子
から生じる反射回折光のうち前記第１，第２の光束に対
応する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、且つ前記測定面に設けられた回折格子から生じ
る反射回折光のうち前記第１，第３の光束に対応する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、前記第１，第３の光束に対応する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
基準信号と前記第１，第２の光束に対応する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、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前記
ステージにおける法線方向の位置及び前記測定面内で互
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. Diffraction in which diffracted light is two-dimensionally distributed on a measurement surface.
Displacement detection parallel to the measurement surface on the stage with a grid
One of the directions and the direction normal to the measurement surface
The first and second luminous flux from different directions
In addition to making it incident,
Inject a third light beam whose angle is different from the normal of the measurement surface.
Sample surface irradiating means and diffraction grating provided on the measurement surface
Of the reflected diffracted light generated from
The two corresponding light fluxes are combined and overlapped so as to interfere with each other.
And from the diffraction grating provided on the measurement surface
2 of the reflected and diffracted light corresponding to the first and third light beams
Combine light fluxes and superimpose them so that they interfere with each other
Optical means and two light fluxes corresponding to the first and third light fluxes
Has a frequency equal to the beat caused by wave interference
Reference signal and waves of two light beams corresponding to the first and second light beams
It measures the phase difference from the beat signal caused by dynamic interference.
And a pattern using a charged particle beam.
For moving the sample provided in the drawing device.
The position on the stage in the direction of the normal line and the position in the measurement plane
A sample surface position measuring device characterized by detecting displacement in two directions orthogonal to each other .
性のある第１，第２の光ビームを生成する第１のステッ
プと、前記第１，第２のビームの一方から第３の光ビー
ムを生成する第２のステップと、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、前記測定面
と平行な変位検出方向のうちの一方と、前記測定面にお
ける法線方向とが成す面に対し、互いに異なる方向から
前記第１，第２の光ビームを照射するとともに、前記第
１，第２の光ビームに対して前記試料の測定面の法線と
異なる角度で前記第３の光ビームを照射する第３のステ
ップと、前記試料の測定面で反射または回折した前記第
１乃至第３の光ビームを受ける第４のステップと、前記
第４のステップで受けた前記第１，第３の光ビームの光
学的演算を行って選択的に重ね合わせるとともに、前記
第１，第２の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５のステップと、前記第５のステップで光
学的演算を施した光信号をそれぞれ第１，第２の電気信
号に変換する第６のステップと、前記第６のステップで
変換された第１の電気信号と第２の電気信号との位相差
を演算する第７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及び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。3. A coherent signal which is modulated by a small amount of different frequencies.
A first step of generating a first and a second light beam having a property , and a third light beam from one of the first and the second beam.
The second step of generating the beam and the second order diffracted light on the measurement surface.
On the sample on which the diffraction grating to be originally distributed is formed,
On one side of the displacement detection direction parallel to
From a direction different from the plane formed by the normal direction
While irradiating the first and second light beams,
1, the normal to the measurement surface of the sample with respect to the second light beam,
A third step of irradiating the third light beam at a different angle and the third step of being reflected or diffracted by the measurement surface of the sample .
A fourth step of receiving the first to third light beams;
The optical calculation of the first and third light beams received in the fourth step is performed to selectively superimpose them , and
Performs optical calculation of the first and second light beams to selectively overlap them.
A fifth step of bringing it, the fifth first respective light signals subjected to optical calculation at step, a sixth step of converting the second electrical signal, converted by the sixth step A seventh step of calculating a phase difference between the first electric signal and the second electric signal, the position being in a direction normal to the measurement surface of the sample and orthogonal to each other in the measurement surface of the sample. A method for measuring a sample surface position, which comprises detecting a displacement in a direction.
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 JPH1026513A (en) | 1998-01-27 |
| JP3364382B2 true 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 |
|---|---|
| JP (1) | JP3364382B2 (en) |
Families Citing this family (23)
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1996
- 1996-07-12 JP JP18355496A patent/JP3364382B2/en not_active Expired - Lifetime
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|---|---|
| JPH1026513A (en) | 1998-01-27 |
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