Patent ID: 7576858

Claim:
A position detecting method that selects some out of plural shots formed on a plate, measures a position of the alignment mark in the selected shots using an alignment detection optical system, and aligning the plate based on a result of a measurement value, said position detecting method comprising the steps of: taking a mark image of the alignment mark on the plate using the alignment detection optical system; calculating a position of the mark image; obtaining an evaluation value of the mark image; and determining a position of the alignment mark by correcting the measurement value using the evaluation value, wherein a corrective equation Mi=M 1 i −α·Ei is met, where i is a selected shot, M 1 i is the position of the mark image, Ei is the evaluation value of the mark image, and α is a corrective coefficient, and wherein the corrective coefficient α is calculated as a gradient of an approximate line by a method comprising the steps of: obtaining a residual of the selected shot when a position of the plate is corrected by six components of a positional offset of the shot which includes shift components Sx and Sy in xy directions, magnification components Bx and By in xy directions, and rotational components θx about a x axis and θy and about a y axis; forming a second evaluation mark on a first evaluation mark on the plate after a position of the plate is corrected; measuring a position of the second evaluation mark relative to the first evaluation mark using a detection apparatus different from the alignment detection optical system; and adding the residual to a position of the second evaluation mark, and obtaining the approximate line from a least squares method that uses a result of addition and the evaluation value of the mark image.