POSITION CORRECTION IN Y OF MASK OBJECT SHIFT DUE TO Z OFFSET AND NON- PERPENDICULAR ILLUMINATION

摘要

POSITION CORRECTION IN Y OF MASK OBJECT SHIFT DUE TO Z OFFSET AND NON- PERPENDICULAR ILLUMINATION In a reflective lithographic projection apparatus, shifts in the image of a pattern of a mask in the scanning direction caused by variations in the position of the pattern surface of the mask along the optical axis are corrected by shifting of the relative position of the mask and/or the substrate in the scanning direction. Correction of the image rotation error may also be accomplished by rotation of the relative positions of the mask and/or the substrate about the optical axis. Variations in the position of the pattern surface of the mask along the optical axis may be determined by interferometers upon installation of the mask to the lithographic projection apparatus. The variations may be mapped and stored to provide control of the lithographic projection apparatus.