Patent ID: 6101047
Filing Date: 2000-08-08
Classification: G02B,G03F

Abstract:
A catadioptric optical system for lithography, which is used to expose a wafer to a light in fabricating a semiconductor, the catadioptric optical system comprising:a first lens group disposed at the rear end of a light source, and performing an astigmation control on a mask irradiated by the light source;a folding mirror for changing the direction of the radiation having passed through the first lens group;a second lens group disposed at the end of the folding mirror, and having a function of performing an astigmation control for the refracted radiation and focussing the radiation;a polarized beam splitter disposed at the rear end of the second lens group, and reflecting an incident polarized beam of the light source having passed through the second lens group;a first wave plate disposed on the polarized beam splitter, converting the linearly polarized beam reflected from the polarized beam splitter to a circularly polarized beam, and converting the circularly polarized beam to the linearly polarized beam again;a spherical mirror for reflecting the circularly polarized beam having passed through the first wave plate;a second wave plate for converting the linearly polarized beam having passed through the first wave plate to a circularly polarized beam; anda third lens group for performing the final astigmation control for the circularly polarized beam having passed through the second wave plate, and transferring information on a mask to the wafer.