Silicon Oxidation and SiO2 Interface of Thin Oxides.

High Resolution Transmission Electron Microscopy HRTEM and ellipsometry techniques have been employed to measure thicknesses of silicon oxide, grown at 800 C in dry oxygen, in the thickness range of 2 to 20 nm. While the oxide growth data measured from TEM obey a linear behavior, those obtained from ellipsometry are seen to follow a linear-parabolic law. The interface structure as function of the increasing oxide thickness was studied using HRTEM. At these oxidation temperatures, we do not see the earlier reported systematic dependence of roughness at the interface on the oxide thickness for oxides grown at 900 C. Attempts aimed at correlating the high resolution transmission electron micrographs with some physical parameters like the refractive index and the dielectric breakdown lead us to considerations of the importance of the effect of protrusions of silicon atoms of 1nm size into SiO2 layers on the interface properties. These findings lead us to explain some key features concerning the refractive index, density and dielectric strength of thin SiO2.