JPH07117371B2 - measuring device - Google Patents

measuring device

Info

Publication number
JPH07117371B2
JPH07117371B2 JP62175239A JP17523987A JPH07117371B2 JP H07117371 B2 JPH07117371 B2 JP H07117371B2 JP 62175239 A JP62175239 A JP 62175239A JP 17523987 A JP17523987 A JP 17523987A JP H07117371 B2 JPH07117371 B2 JP H07117371B2
Authority
JP
Japan
Prior art keywords
measuring
measured
interference
reflected
distance
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP62175239A
Other languages
Japanese (ja)
Other versions
JPS6418002A (en
Inventor
昭一 谷元
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nikon Corp
Original Assignee
Nippon Kogaku KK
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nippon Kogaku KK filed Critical Nippon Kogaku KK
Priority to JP62175239A priority Critical patent/JPH07117371B2/en
Publication of JPS6418002A publication Critical patent/JPS6418002A/en
Publication of JPH07117371B2 publication Critical patent/JPH07117371B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70691—Handling of masks or workpieces
    • G03F7/70716—Stages

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)
  • Length Measuring Devices By Optical Means (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Description

【発明の詳細な説明】 〔産業上の利用分野〕 本発明はレーザ干渉計を用いた位置測定装置に関するも
のである。TECHNICAL FIELD The present invention relates to a position measuring apparatus using a laser interferometer.

〔従来の技術〕[Conventional technology]

周波数安定化されたヘリウム−ネオン（He−Ne）レーザ
を光源としたレーザ干渉計は精密な測長や座標測定に利
用されている。代表的な例はヒューレット・パッカード
社より販売されているシステムである。従来のこの種の
装置を高精度の要求される計測に用いる場合において
は、空気の屈折率揺らぎを防ぐ為に、温度安定化された
特別の空調を行ない、±0.1℃以内の空気温度の安定化
を行ない、また気象の変化に伴なう大気圧変化に対応す
るのに大気圧をモニターして波長補正を行なっている。
さらに全く別の空気の屈折率補正法の例として、特開昭
58−87447号公報、又は特開昭58−169004号公報に開示
されているように２波長干渉計を用いるこのも考えられ
ているが、装置が複雑になり、コストが高いので製品化
されていない。A laser interferometer using a frequency-stabilized helium-neon (He-Ne) laser as a light source is used for precise length measurement and coordinate measurement. A typical example is the system sold by Hewlett-Packard Company. When using this type of conventional equipment for highly accurate measurement, to prevent fluctuations in the refractive index of the air, special temperature-controlled air conditioning is performed to stabilize the air temperature within ± 0.1 ° C. The wavelength is corrected by monitoring the atmospheric pressure in order to respond to changes in atmospheric pressure due to changes in weather.
Further, as an example of a completely different method for correcting the refractive index of air, Japanese Patent Laid-Open No.
It is also considered to use a two-wavelength interferometer as disclosed in Japanese Patent Laid-Open No. 58-87447 or Japanese Patent Laid-Open No. 58-169004, but since the device becomes complicated and the cost is high, it has been commercialized. Absent.

〔発明が解決しようとする問題点〕[Problems to be solved by the invention]

従来の空気の温度安定化を行なうような装置において
も、空気の屈折率揺らぎによる計測値のばらつきは無視
できない。例えば最近のLSI製造におけるストッパー
（投影型露光装置）のステージの位置決めにおいては位
置決め再現性は３σ＝0.08〜0.15μｍであるが、このう
ち相当の部分が1Hz〜100Hzの周波数成分をもつレーザ干
渉計出力の揺らぎによるものと考えられる。計測時間を
十分長くとって、計測値を平均化すれば干渉計の揺らぎ
の影響は小さくなるが、高速のステージ位置決めや、高
速ステージ走査時の計測に対応できないといった問題が
生じる。Even in a conventional device that stabilizes the temperature of air, variations in measured values due to fluctuations in the refractive index of air cannot be ignored. For example, in the positioning of a stopper (projection exposure apparatus) stage in recent LSI manufacturing, the positioning reproducibility is 3σ = 0.08 to 0.15 µm, but a considerable part of this is a laser interferometer having a frequency component of 1 Hz to 100 Hz. This is probably due to fluctuations in the output. If the measurement time is set sufficiently long and the measured values are averaged, the effect of fluctuations of the interferometer will be reduced, but problems such as high-speed stage positioning and measurement during high-speed stage scanning cannot be achieved.

本発明はこの様な従来の問題点を解決し、簡単な方法で
空気の屈折率揺らぎによる干渉計の計測値の揺らぎを減
少させることを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to solve such a conventional problem and reduce fluctuations in the measurement value of an interferometer due to fluctuations in the refractive index of air by a simple method.

〔問題点を解決する為の手段〕[Means for solving problems]

上記問題解決の為に、本発明ではレーザ干渉計の移動鏡
へ往復するレーザビーム（測定用ビームと反射ビーム）
の通過する部分に、一定の向きで風を流すことにした。
さらにレーザビームの風上側と風下側のビーム部分によ
る計測値の差の値を処理して揺らぎによる計測値のばら
つきを補正することとした。In order to solve the above problems, the present invention uses a laser beam (measurement beam and reflected beam) that reciprocates to and from a moving mirror of a laser interferometer.
I decided to let the wind flow in a certain direction through the part where the.
Furthermore, it was decided to correct the variation in the measured values due to fluctuations by processing the value of the difference in the measured values of the laser beam on the leeward side and the leeward side.

〔作用〕[Action]

本発明では移動ミラーに対して往復するレーザビームに
対して、個別に温調された風を流すので、干渉計の計測
揺らぎを低減できる。さらに、本発明ではレーザビーム
の風上側と風下側の部分が、風向きに対して、常に同じ
向きになるような光学系と風向きの関係としているの
で、干渉計の出力の揺らぎの時間変化が、常に風上側か
ら風下側への順に生じるので、計測値の時間変化率が即
時にわかり、風速をほぼ一定とすれば、干渉計の計測値
の揺らぎ成分のみを時間遅れを生じることなく計測でき
る。この計測値の揺らぎ成分の大きさだけ従来の計測法
により得られた計測値に対して補正すれば揺らぎの変化
を補償できる。In the present invention, the temperature-controlled wind is individually supplied to the laser beam that reciprocates with respect to the moving mirror, so that the measurement fluctuation of the interferometer can be reduced. Further, in the present invention, the windward and leeward portions of the laser beam have a relationship of the optical system and the wind direction such that the direction is always the same with respect to the wind direction. Since it always occurs in the order from the windward side to the leeward side, the time change rate of the measured value can be immediately known, and if the wind speed is almost constant, only the fluctuation component of the measured value of the interferometer can be measured without causing a time delay. A change in fluctuation can be compensated by correcting the measured value obtained by the conventional measuring method by the magnitude of the fluctuation component of the measured value.

〔実施例〕〔Example〕

第１図は本発明の実施例による位置検出装置を精密移動
ステージの座標測定に適用したときの構成の斜視図であ
り、１は周波数安定化したレーザ光源であって、ゼーマ
ン効果を用いて約2MHzだけ周波数の異なった互いに偏光
特性の異なった２成分を含む光束２を出力する。３はミ
ラーであり光束２は図に見えないビームスプリッターに
よりステージのｘ方向計測用のＸビーム4Xとｙ方向計測
用のＹビーム4Yに分割され、Ｘ干渉計ユニット5XとＹ干
渉計ユニット5Yに導かれる。Ｘ干渉計ユニット5XはＸミ
ラーMXのｘ方向の移動量を測定し、5YはＹミラーMYのｙ
方向の移動量を測定する。STは互いに直交したＸミラー
MXとＹミラーMYを載置して移動するステージであり、
Ｘ、Ｙ方向に平行に２次元移動する。ステージST上には
ウェハ等の位置決め対象物の設置されるオルダーWHがあ
る。FIG. 1 is a perspective view of a configuration when a position detecting device according to an embodiment of the present invention is applied to coordinate measurement of a precision moving stage, and 1 is a frequency-stabilized laser light source, which uses the Zeeman effect. A light beam 2 including two components having different polarization characteristics different in frequency by 2 MHz is output. Reference numeral 3 denotes a mirror, and the light beam 2 is divided into an X beam 4X for measuring the x direction of the stage and a Y beam 4Y for measuring the y direction of the stage by a beam splitter which is not visible in the figure, and is divided into an X interferometer unit 5X and a Y interferometer unit 5Y. Be guided. The X interferometer unit 5X measures the amount of movement of the X mirror MX in the x direction, and 5Y the y of the Y mirror MY.
Measure the amount of movement in the direction. ST is an X mirror orthogonal to each other
It is a stage that moves by mounting MX and Y mirror MY.
It moves two-dimensionally parallel to the X and Y directions. On the stage ST is an older WH on which a positioning object such as a wafer is installed.

FNはファンであり、風をＸダクトDCXとＹダクトDCYにゴ
ミ除去のフィルターFLを経て送る働きをする。Ｘダクト
DCXとＹダクトDCYの各送風口はＸミラーMX、ＹミラーMY
の移動軌跡と空間的に干渉しないように配置され、計測
用にＸミラーMXやＹミラーMYに向かうレーザビームの部
分に上方から温度安定化されたほぼ一定速の風を送る。
風の空気温度は装置の周辺環境の空調の温度と一致させ
るのが良い。FN is a fan, and works to send the wind to the X duct DCX and the Y duct DCY through the dust removal filter FL. X duct
The DCX and Y duct DCY air outlets are X mirror MX and Y mirror MY.
Is arranged so as not to spatially interfere with the movement locus of the laser beam, and the temperature-stabilized wind is sent from above to the portion of the laser beam toward the X mirror MX or the Y mirror MY for measurement.
The air temperature of the wind should match the temperature of the air conditioner in the environment surrounding the device.

第２図はレーザ干渉計のＸ軸の構成図であり、干渉計部
分は正面図が示されている。第３図には干渉計の上面図
が示されている。第３図にはレーザ干渉計の光路が示さ
れている。レーザ光源１を射出したレーザビームB1は偏
光ビームスプリッター10により２つに分割され、偏光ビ
ームスプリッター10を通過した一方の偏光ビームはλ/4
板13を通って測長用のビームB2となってＸミラーMXで反
射して戻る。λ/4板を逆に通ったビームは偏光状態が反
転され、偏光ビームスプリッター10で反射され、プリズ
ム11で反射した後、偏光ビームスプリッター10で反射さ
れ、ビームB3となって再びＸミラーMXで反射される。戻
ったビームは偏光ビームスプリッター10を通過してビー
ム分割器14に向かう。このビーム分割器14は入射したビ
ームを、そのビーム径の中心で２つに分割するためのプ
リズム状の反射面を有し、分割されたビームの夫々は光
電検出器DX1、DX2によって別々に受光される。FIG. 2 is a configuration diagram of the X axis of the laser interferometer, and a front view of the interferometer portion is shown. A top view of the interferometer is shown in FIG. The optical path of the laser interferometer is shown in FIG. The laser beam B1 emitted from the laser light source 1 is split into two by the polarization beam splitter 10, and one polarization beam passing through the polarization beam splitter 10 is λ / 4.
The beam B2 for length measurement passes through the plate 13 and is reflected by the X mirror MX to return. The beam passing through the λ / 4 plate in the opposite direction is inverted in polarization state, reflected by the polarization beam splitter 10, reflected by the prism 11, and then reflected by the polarization beam splitter 10, becoming a beam B3 again by the X mirror MX. Is reflected. The returned beam passes through the polarization beam splitter 10 toward the beam splitter 14. The beam splitter 14 has a prism-shaped reflecting surface for splitting the incident beam into two at the center of the beam diameter, and the split beams are respectively received by the photoelectric detectors DX1 and DX2. To be done.

一方、レーザビームB1のうち他方の偏光成分は、参照光
として偏光ビームスプリッター10で反射され、プリズム
12で反射された後、偏光ビームスプリッター10内で測長
用ビームの戻りの光路と合成され、ビーム分割器14に入
射する。On the other hand, the other polarization component of the laser beam B1 is reflected by the polarization beam splitter 10 as reference light,
After being reflected by 12, it is combined with the returning optical path of the measuring beam in the polarization beam splitter 10 and is incident on the beam splitter 14.

第２図において、ＸダクトDCXからは矢印18のようにほ
ぼ一様な速度で温度安定化した風を測長ビームの経路に
送る。ビーム分割器14により、戻ってきたレーザビーム
は断面内上側と下側に２分割されて反射され、それぞれ
光電検出器DX1、DX2に入射する。検出器DX1、DX2は参照
光と測長光とに周波数差があるためビート信号を出力
し、このビート信号出力はレーザ光源１からの参照用差
周波数信号（約2MHz）と共に、信号処理系CX1とCX2に入
力され、ヘテロダイン検出される。信号処理系CX1とCX2
からはそれぞれ、座標カウント出力（例えば0.01μｍの
分解能）が得られ、これを補正回路15に入力して、補正
された干渉計出力（測長値）16を得る。In FIG. 2, the temperature-stabilized wind is sent from the X duct DCX to the path of the measuring beam at a substantially uniform velocity as indicated by an arrow 18. The beam splitter 14 splits the returned laser beam into two, that is, the upper side and the lower side in the cross section, which are reflected and enter the photoelectric detectors DX1 and DX2, respectively. The detectors DX1 and DX2 output a beat signal because there is a frequency difference between the reference light and the length measurement light, and this beat signal output is output together with the reference difference frequency signal (about 2 MHz) from the laser light source 1 in the signal processing system CX1. Is input to CX2, and heterodyne is detected. Signal processing system CX1 and CX2
Respectively, a coordinate count output (for example, a resolution of 0.01 μm) is obtained, and this is input to the correction circuit 15 to obtain a corrected interferometer output (length measurement value) 16.

ビームB2、B3は風18の流れに対し、断面の向きが反転し
ない形で光学系が構成されている。送風する空気の温度
が安定化されたとしてもある程度の温度ムラは存在し、
温度が周辺と少し異なった空気塊が風に乗って移動して
いる。従ってＸミラーMXが静止した状態でビームB2、B3
の上部と下部をそれぞれ独立に計測すると、上部の計測
値に対して下部の計測値は時間が遅れて現われる。ま
た、ＸミラーMXが移動中であれば、上部と下部の計測値
の差即ち、検出器DX1、DX2による計測値の差は空気揺ら
ぎによる時間変化値を示している。The beams B2 and B3 have an optical system configured such that the direction of the cross section is not inverted with respect to the flow of the wind 18. Even if the temperature of the blown air is stabilized, there is some temperature unevenness,
An air mass whose temperature is slightly different from the surroundings is moving on the wind. Therefore, with the X mirror MX at rest, the beams B2 and B3 are
When the upper part and the lower part of the are measured independently, the measured value of the lower part appears later than the measured value of the upper part. Further, when the X mirror MX is moving, the difference between the upper and lower measurement values, that is, the difference between the measurement values of the detectors DX1 and DX2 indicates a time change value due to air fluctuation.

信号処理系CX1からの計測出力をx1（ｔ）、信号処理系C
X2からの計測出力をx2（ｔ）とする。これらの出力x1
（ｔ）、x2（ｔ）は決められた位置（例えばステージST
の原点）で同時に零になるようにリセットされるものと
する。ここで出力x1（ｔ）とx2（ｔ）の差Δｘ（ｔ）は
式（Ａ）で表わされる。The measurement output from the signal processing system CX1 is x1 (t), the signal processing system C
The measurement output from X2 is x2 (t). These outputs x1
(T) and x2 (t) are fixed positions (eg stage ST
It should be reset to zero at the same time). Here, the difference Δx (t) between the outputs x1 (t) and x2 (t) is expressed by the equation (A).

Δｘ（ｔ）＝x1（ｔ）−x2（ｔ） …（Ａ） 風速が一定であるとすると という関係があるので、x1（ｔ）、x2（ｔ）の空気の屈
折率揺らぎによる変化分xa（ｔ）はｋを比例定数として と表わされる。k1は、空気の屈折率揺らぎによる変動以
外の変動要因をなくした時にxa（ｔ）が零になるように
決定される。Δx (t) = x1 (t) −x2 (t) (A) If the wind speed is constant Therefore, the variation x a (t) of x1 (t) and x2 (t) due to the fluctuation of the refractive index of air is k, where k is a proportional constant. Is represented. k 1 is determined so that x a (t) becomes zero when the variation factors other than the variation due to the fluctuation of the refractive index of air are eliminated.

式（Ｃ）は適当な時間々隔Ｔを用いて とも表わせる。Ｔの値としては風がレーザビームを横切
る時間以上であればよい。また定数k2については式
（Ｃ）のk1と同様に決定される。この式（Ｄ）は一定時
間Ｔ内で生じるx1（ｔ）とx2（ｔ）の差を積算し、定数
k2をかけることにより演算される。Equation (C) uses the appropriate time interval T Can be expressed as The value of T may be at least the time when the wind crosses the laser beam. Further, the constant k 2 is determined in the same manner as k 1 of the formula (C). This equation (D) integrates the difference between x 1 (t) and x 2 (t) that occurs within a fixed time T,
It is calculated by multiplying by k 2 .

最終的に揺らぎを補正された出力x0（ｔ）は、 x0（ｔ）＝x1（ｔ）−xa（ｔ） ……（Ｅ） 又は x0（ｔ）＝x2（ｔ）−xa（ｔ） ……（Ｆ） 又は のいずれかの式により計算される。従って補正回路15は
上記式（Ｄ）と式（Ｅ）、（Ｆ）、（Ｇ）のいずれかと
に基づいて時間間隔Ｔ毎に干渉計出力16、すなわち出力
x0（ｔ）を決定する。Finally, the fluctuation-corrected output x 0 (t) is x 0 (t) = x1 (t) −x a (t) (E) or x 0 (t) = x2 (t) −x a (t) ... (F) or It is calculated by one of the formulas. Therefore, the correction circuit 15 outputs the interferometer output 16 at each time interval T, that is, the output based on the equation (D) and one of the equations (E), (F), and (G).
Determine x 0 (t).

空気の温度変動や圧力変動がある場合には温度センサ又
は圧力センサ出力を補正回路15に入力してレーザ光の波
長補正を行なえばよい。これは従来から公知の波長補正
により可能である。When there is a temperature fluctuation or a pressure fluctuation of the air, the temperature sensor or pressure sensor output may be input to the correction circuit 15 to correct the wavelength of the laser light. This is possible by the conventionally known wavelength correction.

また、レーザ干渉計出力が音波の圧力波により変動する
場合は、高速応答の圧力センサ又はマイクロフォン等の
音響トランスデューサ17を用いて、音波による波長補正
を行なえばよい。Further, when the output of the laser interferometer fluctuates due to the pressure wave of the sound wave, the wavelength correction by the sound wave may be performed using the acoustic transducer 17 such as a high-speed response pressure sensor or a microphone.

以上の実施例においては２次元の座標測定の例を挙げた
が、１次元、又は３次元でも同様の測定ができる。また
レーザ光源１はゼーマン安定化レーザに限るものではな
く、ラムディップ安定型周波数安定化レーザ等の他の方
式のレーザ光源であってもよい。その場合、レーザ干渉
計の信号処理は異なるが、基本的に本発明の適用が可能
である。In the above embodiments, the example of the two-dimensional coordinate measurement is given, but the same measurement can be performed in the one-dimensional or the three-dimensional. Further, the laser light source 1 is not limited to the Zeeman-stabilized laser, and may be a laser light source of another system such as a Lamb dip stable type frequency stabilized laser. In that case, although the signal processing of the laser interferometer is different, the present invention is basically applicable.

また、以上の実施例の説明においては１つのレーザビー
ムを横切るように送風したとき、ビームの風上側と風下
側とで別々に干渉の検出を行なう例を示したが、風上
側、風下側を別々の２本のレーザビームにしてもよい。
すなわち風の流れる方向に所定間隔で独立のレーザ干渉
計を設け、上記x1（ｔ）、x2（ｔ）を検出すればよい。
この場合、もとのレーザ光源を別々にすることもでき
る。具体的には第４図に示すように、移動ミラーMXの反
射平面（ｙ−ｚ平面と平行）MXrの上下に平行な２本の
測定用ビーム（反射ビーム）B2u、B2dが照射されるよう
に２つの独立したレーザ干渉計IFMu、IFMdを設ける。こ
の干渉計IFMu、IFMdはそれぞれ独立に移動ミラーMXのｘ
方向の位置や距離を計測し、計測値CPu、CPdを出力す
る。計測値CPu、CPdは、移動ミラーMX（ステージST）が
基準位置にきたとき同一値になるように予めセットされ
ている。そして補正回路15は先の実施例と同様に計測値
CPu、CPdの入力に基づいて、空気の屈折率のゆらぎによ
る変動量を補正（あるいは低減）した干渉計計測値16を
出力する。Further, in the above description of the embodiments, when the air is blown across one laser beam, the example in which the interference is detected separately on the windward side and the leeward side of the beam is shown. Two separate laser beams may be used.
That is, it is only necessary to provide independent laser interferometers at predetermined intervals in the wind flow direction and detect x1 (t) and x2 (t).
In this case, the original laser light sources may be separate. Specifically, as shown in FIG. 4, two measurement beams (reflected beams) B2u and B2d parallel to the upper and lower sides of the reflection plane (parallel to the yz plane) MXr of the moving mirror MX are irradiated. There are two independent laser interferometers IFMu and IFMd. The interferometers IFMu and IFMd are independent of the x
It measures the position and distance in the direction and outputs the measured values CPu and CPd. The measured values CPu and CPd are preset so that they will have the same value when the moving mirror MX (stage ST) reaches the reference position. Then, the correction circuit 15 is similar to the previous embodiment in that the measured value
Based on the inputs of CPu and CPd, the interferometer measurement value 16 in which the fluctuation amount due to the fluctuation of the refractive index of air is corrected (or reduced) is output.

このような構成においても、温度安定化されたほぼ一定
速度の風18が、先の実施例と同様に上から下に、すなわ
ち測定用ビームB2uからB2dに向けて流れるようにする。
尚、測定用ビームB2u、B2dは第４図ではそれぞれ１本づ
つしかもたない、所謂シングルビームタイプの干渉計と
して説明したが、先の実施例の第３図に示したように、
１つの干渉計が２本（又はそれ以上）の測定用ビーム
（反射ビーム）を有するダブルビームタイプのものでも
同様に利用できる。Also in such a configuration, the temperature-stabilized wind 18 having a substantially constant velocity is made to flow from the top to the bottom, that is, from the measurement beams B2u to B2d, as in the previous embodiment.
The measuring beams B2u and B2d have been described as so-called single-beam type interferometers each having only one measuring beam in FIG. 4, but as shown in FIG. 3 of the previous embodiment,
A double beam type in which one interferometer has two (or more) measuring beams (reflected beams) can be used as well.

ところで補正回路15での演算は、一定の時間間隔Ｔ毎に
行なわれるとしたが、ステージSTが一定距離だけ移動す
る毎に行なってもよい。さらにステージSTの移動中は一
定距離毎に補正演算を行ない、ステージSTの停止中は一
定時間毎に補正演算を行なうように切替えてもよい。ま
た補正回路15の演算の式（Ｄ）において、定数k2の値を
ステージSTの位置（又は移動速度）に応じて逐次変化さ
せるようにするとよい。これはダクトからの風速がステ
ージ位置（速度）等に応じて変化することに対応するた
めである。By the way, the calculation in the correction circuit 15 is performed every fixed time interval T, but it may be performed each time the stage ST moves by a fixed distance. Further, the correction calculation may be performed at regular intervals while the stage ST is moving, and the correction calculation may be performed at regular intervals while the stage ST is stopped. In addition, in the calculation formula (D) of the correction circuit 15, the value of the constant k 2 may be sequentially changed according to the position (or moving speed) of the stage ST. This is to cope with the fact that the wind speed from the duct changes according to the stage position (speed) and the like.

また、補正回路15は常時、空気の屈折率のゆらぎによる
測定値の変動を補正するように構成したが、ステージST
の移動のさせ方（ステッパーの場合はステップアンドリ
ピート方式）によっては常時補正しなくてもよい。例え
ばステップアンドリピート方式の露光装置では、ウェハ
上の１つのショット領域に対して露光している間（0.2
〜0.5秒間）は、ゆらぎによる干渉計出力値の変動はス
テージSTの位置サーボ系が応答するため、ステージSTが
微動してしまうことがある。これは露光されたパターン
のぶれ、解像不良を引き起こす。解像不良の防止をする
為だけにはステップアンドリピート方式で露光する場
合、ステージSTの次のショット領域へのステッピング移
動中は、先の式（Ｅ）、（Ｆ）、（Ｇ）等による補正は
特に行なわず、ステッピングが終了した時点から露光完
了時までの間は時間間隔Ｔによる補正を行なうようにす
るとよい。またレーザ干渉計の計測値（又は時系列なカ
ウントパルス）を基準としてウェハ上のアライメントマ
ークを光電検出する場合も、検出されたマークの信号波
形や位置にゆらぎの影響が生じるため、アライメントマ
ークの検出時にも補正回路15が補正動作を行なうように
するとよい。The correction circuit 15 is always configured to correct the fluctuation of the measurement value due to the fluctuation of the refractive index of air.
It is not always necessary to correct depending on the way of moving (step and repeat method in case of stepper). For example, in a step-and-repeat exposure apparatus, one shot area on a wafer is exposed (0.2
For ~ 0.5 seconds), the position servo system of the stage ST responds to fluctuations in the interferometer output value due to fluctuations, so the stage ST may move slightly. This causes blurring of the exposed pattern and poor resolution. When the exposure is performed by the step-and-repeat method only to prevent the resolution failure, during the stepping movement to the next shot area of the stage ST, the above equations (E), (F), (G), etc. are used. The correction is not particularly performed, and the correction may be performed at the time interval T from the time when the stepping is completed to the time when the exposure is completed. Also, when photoelectrically detecting the alignment mark on the wafer with reference to the measurement value of the laser interferometer (or time-series count pulse), fluctuations in the signal waveform and position of the detected mark will affect the alignment mark. It is preferable that the correction circuit 15 also performs the correction operation at the time of detection.

尚、本発明の各実施例では、一方向から温度安定化され
た風を送るだけにしたが、第４図中の矢印19に示すよう
に、不図示の排気系（排気ダクト）と組み合わせて風が
よどむことなく流れるようにしてもよい。In each of the embodiments of the present invention, only the temperature-stabilized air is sent from one direction. However, as shown by an arrow 19 in FIG. 4, a combination with an exhaust system (exhaust duct) not shown is used. The wind may flow without stagnation.

〔発明の効果〕〔The invention's effect〕

以上の様に本発明によれば、空気の屈折率揺らぎを減少
できるという効果が得られるとともに、レーザ干渉計の
揺らぎ成分のみをモニターできるので、このモニター量
を用いて計測値を補正し、屈折率揺らぎの影響を受けな
いより正確な計測値が得られるので有効である。As described above, according to the present invention, it is possible to obtain an effect that the fluctuation of the refractive index of air can be reduced, and it is possible to monitor only the fluctuation component of the laser interferometer. This is effective because more accurate measurement values can be obtained without being affected by rate fluctuations.

【図面の簡単な説明】[Brief description of drawings]

第１図は本発明の実施例による測定装置の構成を示す斜
視図。 第２図は本実施例のＸ干渉計の構成を示す図、 第３図は本実施例のＸ干渉計の構成を示す平面図、 第４図は本発明の他の実施例による測定装置の構成を示
す斜視図である。 〔主要部分の符号の説明〕 １……レーザ光源、DX1、DX2……検知器、 FN……ファン、15……補正回路、 FL……フィルター、ST……ステージ、 DCX、DCY……ダクト、18……風 MX、MY……移動ミラーFIG. 1 is a perspective view showing the configuration of a measuring apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing a configuration of the X interferometer of the present embodiment, FIG. 3 is a plan view showing a configuration of the X interferometer of the present embodiment, and FIG. 4 is a measurement device according to another embodiment of the present invention. It is a perspective view which shows a structure. [Explanation of symbols of main parts] 1 ... Laser light source, DX1, DX2 ... Detector, FN ... Fan, 15 ... Correction circuit, FL ... Filter, ST ... Stage, DCX, DCY ... Duct, 18 …… Wind MX, MY …… Moving mirror

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】レーザ光源からのビームを測定用ビームと
参照用ビームとに分割し、該測定用ビームの被測定物か
らの反射ビームと前記参照用ビームとを重ね合わせて干
渉ビームを作り、該干渉ビームを光電検出することによ
って、前記被測定物の位置や距離を測定する装置におい
て、 温度安定化されたほぼ一定速度の気体流を発生する気体
供給源と； 前記測定用ビームと反射ビームの通過する空間に、該ビ
ームを横切るように前記気体供給源からの気体流を導く
導風手段とを備えたことを特徴とする測定装置。1. A beam from a laser light source is divided into a measuring beam and a reference beam, and a reflected beam from the object to be measured of the measuring beam and the reference beam are superposed to produce an interference beam. In a device for measuring the position and distance of the object to be measured by photoelectrically detecting the interference beam, a gas supply source that generates a temperature-stabilized gas flow at a substantially constant velocity; the measurement beam and the reflected beam. And a wind guide means for guiding a gas flow from the gas supply source across the beam in a space through which the measuring beam passes. 【請求項２】前記導風手段は、前記ビームの通過空間へ
の送風口が前記被測定物の移動軌跡と空間的に干渉しな
いように前記ビームの軸方向に渡って固定的に配置され
ていることを特徴とする特許請求の範囲第１項記載の装
置。2. The air guide means is fixedly arranged in the axial direction of the beam so that a blower port to the passage space of the beam does not spatially interfere with a movement locus of the object to be measured. A device according to claim 1, characterized in that 【請求項３】前記被測定物は、互いに直交する２つの反
射面を有し、前記導風手段は、該２つの反射面にそれぞ
れ照射される前記測定用ビームとその反射ビームの通過
空間にそれぞれ前記気体流を導くことを特徴とする特許
請求の範囲第１項、又は第２項記載の装置。3. The object to be measured has two reflecting surfaces which are orthogonal to each other, and the air guide means is provided in the space for passing the measuring beam and the reflected beam, which are respectively irradiated on the two reflecting surfaces. Device according to claim 1 or 2, characterized in that it respectively directs the gas flow. 【請求項４】前記導風手段は、前記気体流の温度を装置
内の空調温度とほぼ等しく設定することを特徴とする特
許請求の範囲第１項乃至第３項記載の装置。4. The apparatus according to claim 1, wherein the air guide means sets the temperature of the gas flow substantially equal to the air conditioning temperature in the apparatus. 【請求項５】前記導風手段は、前記測定用ビームの軸方
向に渡ってその上方から前記気体流を送ることを特徴と
する特許請求の範囲第１項乃至第４項記載の装置。5. The apparatus according to any one of claims 1 to 4, wherein the air guide means sends the gas flow from above the air beam over the axial direction of the measuring beam. 【請求項６】レーザ光源からのビームを測定用ビームと
参照用ビームとに分割し、該測定用ビームの被測定物か
らの反射ビームと前記参照用ビームとを重ね合わせて干
渉ビームを作り、該干渉ビームを光電検出することによ
って、前記被測定物の位置や距離を測定する装置におい
て、 前記測定用ビームと反射ビームの通過する空間に、該ビ
ームを一方向から横切るように気体を供給する気体供給
手段と； 前記測定用ビームと反射ビームの前記気体に対する風上
部と風下部との各々に対応して前記干渉ビームを２つに
分割する分割手段と； 該分割された２つの干渉ビームの各々を別々に光電検出
する２つの光電検出器と； 該２つの光電検出器の出力信号に基づいて前記被測定物
の位置や距離を計測する計測手段とを備えたことを特徴
とする測定装置。6. A beam from a laser light source is divided into a measuring beam and a reference beam, and a reflected beam from the object to be measured of the measuring beam and the reference beam are superposed to form an interference beam, In a device for measuring the position and distance of the object to be measured by photoelectrically detecting the interference beam, a gas is supplied to a space where the measurement beam and the reflected beam pass so as to cross the beam from one direction. Gas supply means; splitting means for splitting the interference beam into two corresponding to the windward and leeward of the measuring beam and the reflected beam with respect to the gas, respectively; Two photoelectric detectors for photoelectrically detecting each of them; and a measuring means for measuring the position and distance of the object to be measured based on the output signals of the two photoelectric detectors. Stationary device. 【請求項７】前記計測手段は、前記２つの光電検出器の
各出力信号に基づいて前記被測定物の位置や距離を個別
に検出する２つの信号処理回路と、該２つの信号処理回
路で検出された情報に基づいて前記ビームの通過空間の
屈折率のゆらぎによる誤差量を補正する補正回路とを含
むことを特徴とする特許請求の範囲第３項記載の装置。7. The measuring means includes two signal processing circuits for individually detecting the position and distance of the object to be measured based on the output signals of the two photoelectric detectors, and the two signal processing circuits. 4. The apparatus according to claim 3, further comprising a correction circuit that corrects an error amount due to fluctuation of a refractive index of the beam passing space based on the detected information. 【請求項８】被測定物にレーザ光源からの測定用ビーム
を照射し、その反射ビームと前記レーザ光源から得られ
る別の参照用ビームとを干渉させて干渉ビームを作り、
該干渉ビームを光電検出することによって、前記被測定
物の位置や距離を測定する装置において、 前記被測定物に第１の測定用ビームを照射し、その反射
ビームと第１の参照用ビームとを干渉させて第１の干渉
ビームを作り、前記被測定物の位置や距離を測定する第
１干渉測定手段と； 前記第１の測定用ビームと平行に前記被測定物に第２の
測定用ビームを照射し、その反射ビームと第２の参照用
ビームとを干渉させて第２の干渉ビームを作り、前記被
測定物の位置や距離を測定する第２干渉測定手段と； 前記第１の測定用ビームが風上に位置し、前記第２の測
定用ビームが風下に位置するように、該ビームを横切る
方向から気体を供給する気体供給手段とを備えたことを
特徴とする測定装置。8. An interference beam is produced by irradiating an object to be measured with a measurement beam from a laser light source and causing the reflected beam to interfere with another reference beam obtained from the laser light source.
In a device for measuring the position and distance of the object to be measured by photoelectrically detecting the interference beam, the object to be measured is irradiated with a first measuring beam, and a reflected beam and a first reference beam First interference measuring means for interfering with each other to form a first interference beam and measuring the position and distance of the object to be measured; and a second measuring beam on the object to be measured parallel to the first beam for measurement. Second interference measuring means for irradiating a beam, making a reflected beam and a second reference beam interfere with each other to form a second interference beam, and measuring the position and distance of the object to be measured; A measuring device comprising a gas supply means for supplying gas from a direction traversing the beam so that the measuring beam is located on the upwind side and the second measuring beam is located on the downwind side.
JP62175239A 1987-07-14 1987-07-14 measuring device Expired - Lifetime JPH07117371B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62175239A JPH07117371B2 (en) 1987-07-14 1987-07-14 measuring device

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62175239A JPH07117371B2 (en) 1987-07-14 1987-07-14 measuring device

Related Child Applications (1)

Application Number Title Priority Date Filing Date
JP32148596A Division JP2888215B2 (en) 1996-12-02 1996-12-02 Exposure apparatus and measurement method

Publications (2)

Publication Number Publication Date
JPS6418002A JPS6418002A (en) 1989-01-20
JPH07117371B2 true JPH07117371B2 (en) 1995-12-18

Family

ID=15992693

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Application Number Title Priority Date Filing Date
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