Optical measurement of surface profiles of silicon dioxide films on silicon substrates and carbon coatings on magnetic disks

Current models for recovering the surface profile from optical measurements are inadequate for characterizing surfaces with optically dissimilar regions. This limitation in the model is evidenced in optical measurements of silicon dioxide films on silicon substrates, and carbon films on magnetic recording disk substrates. A new model that accounts for phase changes due to reflection at material boundaries is proposed, which involves measurements at several wavelengths in order to resolve these phase changes. Results of implementation of the new model are presented for silicon dioxide and carbon films.