ENHANCED SILICON OXIDATION IN O-2 AND O-2-F-2

Rate equations are proposed for the description of the enhanced kineti cs observed in the early stages of silicon oxidation in dry O-2 at usu al temperature (T greater than or equal to 600 degrees C) or during th e oxidation in O-2;F-2 at a moderate temperature (400-550 degrees C). Both these equations admit as an approximate solution the time-logarit hm law usually known as the Elovich isotherm, thus showing that this e quation is able to describe not only oxidation at room or slightly hig her 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 th e hypothesis of weakening of the Si-Si backbonds to highly polar silic on bonds like =Si(O-)(2) or =Si-F at the Si-SiO2 interface.