Patent ID: 6151102
Filing Date: 2000-11-21
Classification: G03F

Abstract:
A position detector for use in a projection exposure apparatus to detect a position of a focused image plane at which a focused image of a mask pattern is formed by a radiation flux through a projection optical system having an optical axis, the position detector comprising:a plurality of reference marks disposed in a first direction with predetermined spacings at a position at which the mask pattern is to be placed, the radiation flux illuminating the plurality of reference marks, and thereafter entering the projection optical system to form images of the plurality of reference marks in the focused image plane, the images being arranged in a second direction substantially perpendicular to the optical axis of the projection optical system, and spacings of the images being determined by the predetermined spacings of the reference marks;a radiation receiver having a receiving area movable relative to the images of the reference marks to scan the plurality of images successively, the radiation receiver outputting a reception signal indicating the amount of the radiation flux received at the receiving area, the receiving area being smaller than the spacings separating the images of the reference marks adjacent in the second direction and being larger than each of the images of the reference marks in the second direction;a position detector outputting a position signal indicating the position of the receiving area; anda calculation unit processing the reception signal and the position signal to derive the positions of the images of the reference marks.