Objective with doubly refracting lenses especially a projection objective for microphotolithography and compensation process has two different sets of doubly refracting lenses

摘要

An objective, especially a projection objective for microlithography comprises two sets of doubly refracting lenses of different materials or having different material orientation such that the path difference between the orthogonal polarized rays is less than one quarter wavelength. An objective, especially a projection objective for microlithography comprises two sets of doubly refracting lenses (L108,109,129,130) and (L101-107,110-128) of different materials or material orientation. A main ray (9) and outermost aperture cone (5,7) arise having a path difference for two orthogonal polarized conditions but after passing through the lenses the path difference is less than one quarter wavelength. The outermost opening angle is at least 70% of maximum and the volume of the first lenses is not greater than 20% of the total lens volume. Independent claims are also included for the following: (a) an objective having calcium fluoride and barium fluoride lens groups; (b) a process for compensating for double refraction; (c) a process for semiconductor element production;and (d) a further objective as above