Projection exposure method and projection exposure system therefor

摘要

In a projection exposure method, primary radiation having a center wavelength λ is generated and guided through an illumination system along an illumination path and through a projection system along a projection path. The center wavelength is varied within a wavelength variation range &Dgr;λ having a lower limit λMIN≦̸λ and an upper limit λMAX≧λ. A specific absorption coefficient k(λ) of at least one gaseous absorbent species selected from the group consisting of oxygen (O2), ozone (O3) and water vapor (H2O) present in at least one gas-filled space along at least one of the illumination path and the projection path varies between a minimum absorption coefficient kMIN and a maximum absorption coefficient kMAX within the wavelength variation range such that an absorption ratio (kMAX/kMIN) exceeds 10. A concentration of the absorbent species within the gas-filled space is controlled such that an overall absorption variation effected by the absorbent species for all rays running along differing ray paths towards the image field is maintained below a predetermined absorption variation threshold value.