Effect of High-temperature Annealing on Evaporated Silicon Oxide Films: A Spectroscopic Ellipsometry Study

Abstract

Silicon oxide films, vacuum evaporated and annealed in Ar atmosphere at a temperature of 1000 and 1100ºC have been studied by multiple-angle spectroscopic ellipsometry (SE) in the spectral range of 280-820 nm. The thickness, complex refractive index and composition of the films have been determined from the SE data analysis, performed with multiple-layer optical models and applying the Bruggeman effective medium approximation theory. The SE results have revealed that during annealing at 1000oC the Si clusters with volume fraction of ~ 14 % crystallize in the substoichiometric SiO1.61 matrix, while annealing at 1100oC transforms the oxide structure to a fully stoichiometric SiO2 with embedded nc-Si clusters with enhanced volume fraction of 22%. The TEM micrographs visualized the Si crystallites, which have random distribution in the amorphous oxide matrix and an average size of 3 nm.