An ellipsometric study of W thin films deposited on Si

The results of spectral and angle-dependent ellipsometric measurements of r .f. magnetron-sputtered very thin tungsten films (2/8 nm) deposited onto [1 00] oriented silicon substrates have been reported. Ellipsometric data were taken over the spectral range from 406 to 806 nm. The parameters of the fi lms, namely, film thicknesses and volume fractions for the constituents hav e been calculated from the ellipsometric data by the best fitting procedure using some three layer and four layer optical models. We have estimated th e roughness on the film surfaces and contamination of the films by Si and S iO2 using Maxwell-Garnett and Bruggeman effective medium approximations. Th e roughness of the films and substrate surfaces have also been measured ind ependently on profilometer. The ellipsometric measurements along with compu ter data processing will be useful for quality control during the manufactu ring of the films, which have applications in soft X-ray optical systems. ( C) 1999 Elsevier Science S.A. All rights reserved.