Scattered refractive index profiles of thin silicon oxide film on silicon substrate

Abstract

Randomly scattered depth profiles of refractive index are experimentally observed on thin silicon dioxide films on silicon substrates by means of conventional ellipsometry and gradually chemical etching. Computer simulations with an abrupt model and random uncertainties in ellipsometric angles Ψ and Δ show very similar behavior as experiments, and the distribution of the measured profile in the near interface region is in good agreement with 0.02° standard deviation in Ψ. Simulations also indicate that even very small errors in Ψ, as small as 0.001°, can result in divergent depth profile of the refractive index in the near interface region.