REFLECTION REDUCTION IMAGE-FORMING OPTICAL SYSTEM FOR X-RAY LITHOGRAPHY

摘要

PROBLEM TO BE SOLVED: To obtain sufficient image-forming performance by a simple structure by arranging in order a concave mirror, a flat mirror and a convex mirror from an object side on a common axis, forming the respective concave mirror and convex mirror of nonspherical shape and arranging the convex mirror on the iris surface. SOLUTION: A mask M and a wafer W are synchronized with each other in a ring field for scanning, thereby obtaining an aligner with a wide visual field and an image with high resolution and low distortion aberration. In addition, the wafer side for reduction becomes a telecentric ring field, and since the position of aperture diaphragm is on a convex mirror G2 , the same exposure condition can be obtained within the ring field. An optical path is folded by a planar mirror G3 , so that the optical path from the mask is not blocked with a wafer. Further, since the incident angle of light entering the respective reflecting surfaces G1 to G4 is approximately zero degree, the aberration of wave surface caused by phase shift on respective reflecting surfaces that are formed by multi-layer film can be prevented from generation.