Optical Measurement of Film Growth on Silicon and Germanium Surfaces in Room Air

The thickness and growth kinetics of oxide films on polished silicon and germanium exposed to room air after having been rinsed in hydrofluoric acid were obtained by measuring the ell ipticity of reflected polarized light. Fi lm growth obeys the Elovich equation. Plots of thickness vs. the logarithm of the time in air are l inear after about 15000 sec with slopes of 6.SA/decade (St) and 8.1A/decade (Ge). Immediately a~ter the hydrofluoric acid rinses the films are 10-15A thick and increase in thickness by about l l-12A after one day in air. A small part of the films dissolves in certain organic liquids. Measurements of ell ipticity at two angles of incidence during film growth gave an experimental check of the optical theory. The rates of growth of f i lms--p resumably oxide f i lms--on pol ished Si and Ge in room air fo l lowing a r inse in HF were obtained by measur ing the el-l ipt ic ity of polar ized l ight reflected f rom the sur-