Position detection apparatus, alignment apparatus and methods therefor, and exposure apparatus and device manufacturing method

摘要

An alignment apparatus which detects the position of an alignment mark on a wafer has a low-magnification sensing system including the first imaging optical system and a photoelectric conversion element, and a high-magnification sensing system including the second imaging optical system and a photoelectric conversion element. Detection light from an alignment mark is branched, thereby sensing the alignment mark simultaneously by the low- and high-magnification sensing systems. The positions of the alignment mark are respectively calculated on the basis of the obtained low- and high-magnification images. If the mark position calculated on the basis of the low-magnification image falls within a predetermined range, the mark position calculated on the basis of the high-magnification image is determined to be valid and adopted as the proper alignment mark position.