Dresden 2014 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 1: Application of Thin Films

DS 1.11: Vortrag

Montag, 31. März 2014, 12:15–12:30, CHE 91

Dynamic Effects in the Power Spectral Density Determination of Multilayers with EUV Light — •Anton Haase, Victor Soltwisch, Christian Laubis, and Frank Scholze — Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin

The throughput of EUV lithography systems is presently strongly limited by the available radiant power at the waver level. Besides increasing the power of EUV sources, also the quality of the optical elements plays a key role. With state of the art multilayer mirrors the main cause of diminished reflectance is surface and interface roughness as well as interface diffusion. Both properties lead to diffuse scattering reducing the intensity of specular reflected light in the relevant EUV spectral range around 13.5 nm below the theoretical limit. The intensity distribution of diffusely scattered light provides information on vertical and lateral correlations of spacial frequencies of roughness through the appearance of resonant diffuse scattering (RDS) sheets. The study of off-specular scattering thus serves as a natural tool for the investigation roughness power spectral densities (PSD) of the interfaces. We found that dynamical scattering contributions from thickness oscillations (Kiessig fringes) lead to Bragg lines which intersect the RDS sheets. This causes strong resonant enhancement in the scatter cross section. Thus for power spectral density studies of multilayer interface roughness, resonant dynamical scattering can not be neglected. We considered the scatter enhancement by applying fully dynamic distored wave Born approximation to extract the power spectral density of roughness.