Projection scanning exposure apparatus with synchronous mask/wafer

Abstract

A scanning exposure apparatus has a mask (reticle) and a photosensitive substrate (a wafer) in an imaging relationship across a projection optical system. A mask stage and a wafer stage are moved simultaneously in first (X) direction with a speed ratio corresponding to the magnification of projection, so that a shot area of the photosensitive substrate is scan-exposed to an original pattern of the mask. The mask is provided, over the scanning range of the original pattern, with mask gratings, each composed of plural grating elements arranged at a predetermined pitch along the first (X) direction. The photosensitive substrate is provided with substrate gratings corresponding to said mask gratings. The positional aberration between said mask gratings and the substrate gratings is detected, through the projection optical system, by positional aberration detecting means. At the scanning exposure, either of the mask stage and the substrate stage is driven in the first (X) direction at a constant speed, by first drive control means. The other stage is controlled by second drive control means in such a manner that the relative positional aberration detected by the positional aberration detecting means in the course of movement of the stage, driven by the first drive control means, remains at a predetermined value.