Feasibility of a new absorber material for high NA extreme ultraviolet lithography

Abstract

The extreme-ultraviolet lithography (EUVL) has been regarded as the best candidate to achieve high resolution patterning below 1x nm node. From the Rayleigh criterion, a numerical aperture (NA) should be increased to make the high resolution pattern. A new absorber structure which has sufficient image contrast and small height is needed for realization of high NA optics. In this study, 28 nm-thick ruthenium oxide (RuO2) is suggested for the absorber material. We could obtain higher image contrast and better H-V bias by using the RuO2 absorber compared to the other materials such as TaN and TaBN.