Use the deformation Fresnel zone plate position method of detection and the position detection device

摘要

PROBLEM TO BE SOLVED: To make a diffraction image sharp, and improve the relative position detection accuracy of a mask to a wafer by forming a alignment mark into such a shape that the zone edge of each Fresnel zone is not like an inverted trapezoidal shape but the oblique sides bulge outward along the center axis. SOLUTION: An alignment mark in a position detector uses a deformed Fresnel zone plate 30 in which the zone edges E1-E7 of each of a plurality of Fresnel zones Z1-Z7 is not inverted trapezoidal but the oblique sides bulge outward arcuately along a center axis C2. By forming the shape of the Fresnel zone plate used for an alignment mark, the main focal plane of the Fresnel zone plate can be placed relatively nearer to the main focal plane of an objective of a detection optional set than in the normal inverted trapezoidal Fresnel zone plate, so that the diffraction image of the Fresnel zone plate is made sharp.