FLUORINE ENHANCED OXIDATION OF SILICON AT LOW-TEMPERATURES

We report the oxidation of silicon at and below 550-degrees-C in a mixture of oxygen and fluorine. Introduction of small concentrations of fluorine (<0.1%) in the oxygen ambient increases the oxide growth sharply to rates in excess of 8 angstrom/min where the average fluorine concentration in the oxide can exceed 6 at.%. For each oxidation temperature there was a unique fluorine concentration at which the oxidation rate was at its highest. Fluorine depth profiles in the film were determined by high depth resolution nuclear reaction analysis, and high interface concentrations of fluorine were observed.