Simulation of polychromatic effects in high NA EUV lithography

Abstract

State-of-the-art EUV exposure systems utilize EUV radiation around 13.52 nm with a full band spectrum extending from 13.2 nm to 13.8 nm. The variation of the wavelength in this range modifies the diffraction angles with an impact on the image blur and non-telecentricity effects. Dispersion of the materials on the EUV mirrors and on the 3D mask introduce an additional sensitivity of the imaging characteristics to the exposure wavelength. We employed the simulation models of the Fraunhofer IISB lithography simulator Dr.LiTHO in combination with measured optical material data from PTB to quantify the resulting image impact and to differentiate between the identified contributors to polychromatic imaging effects.