| 摘要 |
<p>PROBLEM TO BE SOLVED: To measure highly accurately at least one of the positions of a reticle and wafer in the directions of their synchronous movements with each other, by air-conditioning through air conditioning mechanisms the optical paths of the measurement beams of an interferometer system for measuring the positional information of the synchronous movement of the reticle with the wafer. SOLUTION: Since the optical paths of the beams of a laser interferometer 36A for an X-axis are long, independent air conditioning mechanisms of each other are mounted on the optical paths. Concretely, fixed covers (cylinders) for covering the optical paths of the beams are so provided that they cover the nearly whole region/partial regions of the optical paths including the one present between a beam splitter and a mobile mirror 34A and/or the one present between the beam splitter and a stationary mirror (it is fastened to the mirror cylinder portion of, e.g. a projective optical system), the beam splitter emitting both the beams which proceed respectively toward the mobile mirror 34A and the stationary mirror. By these air conditioning mechanisms, the optical paths of the measuring beams of the laser interferometer 36A for the X-axis are air-conditioned. As a result, the variation of the measurement value of a scanning aligner caused by the fluctuations of its air conditionings, etc., is prevented from occurring in the course of its scanning exposure even when its optical paths becomes long.</p> |
