Enhanced silicon oxidation in O 2 and O 2:F 2

Abstract

Rate equations are proposed for the description of the enhanced kinetics observed in the early stages of silicon oxidation in dry O 2 at usual temperature ( T ≥ 600° C) or during the oxidation in O 2:F 2 at a moderate temperature (400–550° C). Both these equations admit as an approximate solution the time-logarithm law usually known as the Elovich isotherm, thus showing that this equation is able to describe not only oxidation at room or slightly higher temperature (as well known from the first observation of the time logarithm law in 1922), but also oxidation at much higher temperatures. The physical model advocated for explaining both the early stages of oxidation in dry O 2 and enhanced oxidation in O 2:F 2 is based on the hypothesis of weakening of the Si-Si backbonds to highly polar silicon bonds like =Si(O ) 2 or ≡Si F at the Si SiO 2 interface.