Differential optical reflection spectroscopy of thin TiSi2 films on Si(111)

The microstructures of thin TiSi2 films with nominal thicknesses of 2.4 to 10.8 nm on Si(111) substrates have been estimated in situ. The change of normal incidence optical reflectance was measured in the course of film formation. Surface roughness was monitored by diffuse light scattering. It is an important factor in the analysis of the optical properties. The reflectivity is calculated on the basis of a three-parameter model which accounts for both structural and compositional fluctuations. The values of the parameters agree with the results of electron microscopy studies on TiSi2 films of ∼100 nm. The method presented gives quantitative estimates of coverage, in contrast with Auger electron spectroscopy which suffers from an excessive surface sensitivity.