Scanning exposure apparatus with surface position detecting system

Abstract

A scanning exposure apparatus, wherein a pattern of a surface of a first object placed on a first stage is illuminated with exposure light from a slit aperture of an illumination system, and wherein the pattern of the first object is projected through a projection optical system onto a surface of a second object placed on a second stage while relatively and scanningly moving the first and second stages in a widthwise direction of the slit aperture, in a timed relation and at a speed ratio corresponding to a projection magnification of the projection optical system. The apparatus includes a reference plate provided in a portion of one of the first and second stages and having a predetermined mark, a reflection surface plate provided in a portion of the other of the first and second stages, and a surface position detecting system for projecting the mark of the reference plate onto the reflection surface plate through the projection optical system and, while moving one of the first and second stages in a direction of an optical axis, for detecting the position of the surface of the second object in the direction of the optical axis on the basis of an image reflected by the reflection surface plate.