RELAY LENS USED IN ILLUMINATION SYSTEM OF LITHOGRAPHY SYSTEM

摘要

PURPOSE: A relay lens used in an illumination system of a lithography system is provided to reduce costs and increase transmission by requiring less CaF2 because fewer optical elements are used compared to prior systems. CONSTITUTION: A relay lens is provided in an illumination system for use in microlithography. The relay lens is used to uniformly illuminate a field at a reticle by telecentric light beams with variable aperture size. The relay lens includes a first lens group(204), a second lens group(208), and a third lens group(212). At least one of the second and third lens groups includes a single lens.