Exposure apparatus and method of aligning exposure mask with workpiece

Abstract

An exposure apparatus comprises a light source, a mask plate having an exposure pattern area section and an alignment/reflection area section, a projection lens, a movable stage for holding a workpiece having a workpiece alignment mark, an alignment control and a driver for the movable stage. Before the exposure pattern area section is illuminated by the light source to be projected through the projection lens onto the workpiece, the workpiece is properly aligned with the mask. Alignment between the mask plate and the workpiece is performed by the effective use of the alignment/reflection area section specifically arranged and having a specific structure. The alignment/reflection area section is on that surface of the mask plate which does not face the light source and includes a reflection portion for conducting light from another light source to the workpiece and conducting light scattered from the workpiece and passing through the projection lens to the alignment control and a mask alignment mark portion of providing, when illuminated, an image of the mask alignment mark portion to the alignment control so that it detects the positional relation between the mask alignment mark portion and the workpiece alignment mark and produces a control signal for achieving alignment between the mask plate and the workpiece.