ABERRATION CORRECTING OPTICAL SYSTEM AND ALIGNING DEVICE HAVING THIS OPTICAL SYSTEM

摘要

PROBLEM TO BE SOLVED: To make it possible to correct coma aberrations without affecting other aberrations with simple constitution by providing the optical path of a relay lens with a correcting optical system for offsetting the coma aberrations and offcentering this system, thereby correcting the coma aberrations over the entire part of the optical system. ;SOLUTION: Objective lenses 8, 10 form the primary image of a wafer mark 5 in accordance with the reflected light from the wafer mark 5 and the relay lens 14 disposed in the optical path between an intermediate image 16 and an image plane 15 forms the secondary image of the wafer mark 5 in accordance with the light from the primary mark of the wafer mark 5. The unmagnification erecting afocal system (correcting optical system) 13 disposed in the optical path of the relay lens 14 consists, successively from the objective lens 10 side, a positive lens group 11 and a negative lens group 12 and is capable of moving these lens groups integrally by the arbitrary quantity within the prescribed range along the arbitrary direction perpendicular to the optical axis AX₁ of the alignment optical system 6. The coma aberrations over the entire apart of the optical system are corrected by offcentering this afocal optical system 13.;COPYRIGHT: (C)1997,JPO