Abstract: A mask alignment method of the projection type is disclosed which is based upon a fact that the exit pupil of a projection lens is actually positioned at a finite distance, and wherein a first wafer alignment pattern including a line segment and a second wafer alignment pattern including another line segment are formed on a wafer in those radial directions from the optical axis of a projection lens which intersect with each other approximately at a right angle. A first mask alignment pattern including a line segment and a second mask alignment pattern including another line segment are formed respectively at those positions on a mask which optically correspond to respective positions of the first and second wafer alignment patterns through the projection lens.

Abstract: A mask alignment method of the reduction-projection type comprising the steps of illuminating only regions of alignment patterns formed on a mask and a wafer, before a circuit pattern formed on the mask is projected onto the chips of the wafer through a reduction-projection lens, and aligning the mask and the wafer with each other by detecting the reflected images of both the alignment patterns. The alignment pattern region is illuminated by the light having the same wavelength as the exposure light. In addition, a mask alignment apparatus of the reduction-projection type comprising an illumination device for illuminating the mask. The mask is disposed at a distance from the wafer. The illumination light includes g-line or h-line or a combination of g-line and h-line. The projection lens is interposed between the mask and the wafer so that the circuit pattern formed on the mask is projected on the chips of the wafer on a reduced scale thereby to give the optical printing of the circuit pattern to the wafer.