EUV scattering measurements of optical components

The trend to ever shorter wavelengths in semiconductor lithography generates tremendous challenges for optical components. In particular at the wavelength of next generation lithography 13.5 nm, scattering becomes crucially important with regard to losses and imaging quality. So far, EUV scatter measurements were only possible at synchrotron facilities. Recently, a novel laboratory-sized instrument developed at the Fraunhofer IOF was presented. This instrument is the first system capable of reflectance and angle resolved scattering measurements independent of synchrotron radiation. In this presentation, we report on our new achievements regarding both the setup as well as new measurement and analysis techniques. A dynamic range of 7 orders of magnitude has been accomplished. This enables investigations even of uncoated substrates. To explain the resulting scatter distributions new analysis techniques including the influence of subsurface damage were developed. For multilayer mirrors, the influence of substrate roughness and roughness evolution with increasing period number on the performance is discussed.