| 摘要 |
PROBLEM TO BE SOLVED: To provide a projection aligner which can improve the positioning precision of a substrate surface by precisely detecting the tilting of a substrate without making an optical system complex, even when a step is formed on the substrate surface and then precisely projects a fine pattern for exposure. SOLUTION: A sensor 15 and a synchronous detecting circuit 17 detect positional information on a wafer W in the direction of an optical axis AX of a projection optical system PL as measurement points SP and SPa to SPi set in the projection visual field of the projection optical system PL. A main control unit 30 finds the tilt information on the wafer W among the measurement points SP and SPa to SPi according to the detection result of the sensor 15 and synchronous detecting circuit 17. The detection results among the measurement points SP and SPa to SPi are differentiated, and the tilt information on the wafer W is found from the mean value of the arithmetic results. At this time, a mean value which excludes arithmetic results of the differentiation exceeding a threshold for tilt decision making is found.
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