ILLUMINATION OPTICAL APPARATUS, PROJECTION EXPOSURE APPARATUS, AND DEVICE MANUFACTURING METHOD

摘要

An illumination optical system (IU) of a projection exposure apparatus for projecting and exposing a pattern of a reticle (R) onto a wafer (W) comprises a secondary relay optical system (22) for forming a plane (62) optically conjugate with a reticle surface between an exposure light source (10) and the reticle (R), and an optical path combining mirror (21) for combining exposure light beams (IL1, IL2) from the exposure light source (10) so that they illuminate the reticle surface closely to each other there, wherein the optical path combining mirror (21) includes reflecting surfaces (21a, 21b) for respectively reflecting the exposure light beams (IL1, IL2), and wherein a ridge line (21c) at the boundary between the reflecting surfaces (21a, 21b) is arranged on or near the plane (62).