Light scattering techniques for the characterization of EUV optical components

Because of the short wavelength employed, current developments in lithography for semiconductor manufacturing towards the EUV spectral range involve enormous requirements on the quality of optical surfaces and coatings. A new technique has been established by the Fraunhofer IOF that enables EUV mirror substrates to be characterized before coating with high sensitivity on large areas through light scattering analysis. Furthermore, an instrument for the at-wavelength characterization of reflectance and scattering properties of EUV coatings at 13.5 nm has been developed. Together with the existing modeling techniques these tools provide a complete characterization chain for EUV optical components.