A position detection method for detecting the position of marks comprises the
following
steps: a step for detecting first information relating to the position of the mark
by detecting light from the mark under first measurement conditions; a step for
detecting second information relating to the position of the mark by detecting
light from the mark under second measurement conditions which differ from the first
measurement conditions; and a step for detecting the position of the mark based
on the first and second information, thereby providing a high-precision position
detecting method and device serving as an alignment or overlaying detection device
in an exposure apparatuses used in manufacturing semiconductor devices, wherein
position detection precision is not lost even in the event that the alignment marks
are not symmetrical or there are irregularities in the non-symmetry of multiple
alignment marks within the same wafer.