Silicon Orientation Effects in the Initial Regime of Wet Oxidation

Abstract

Atmospheric pressure wet oxidations at similar to785degreesC were performed on (100), (110), and (111) oriented silicon wafers. The experimental data revealed that the (110) plane experiences rapid initial oxide growth of the same order of magnitude as that which is known to occur during dry oxidation of all orientations of Si. The data also indicated that a crossover in the oxidation rates of the (110) and (111) surfaces occurs similar to that which has been reported for oxidation in dry ambients. Initially, the (110) orientation oxidizes fastest yielding the oxidation rate order (110). (111). (100). As the growth proceeds, however, the oxidation rate of the (111) plane surpasses that of the (110) plane resulting in the order (111). (110). (100). These two anomalous characteristics of silicon oxidation have previously been believed to be limited to dry oxidation. The discovery that rapid initial oxide growth also occurs during wet oxidation of (110) oriented Si reveals that the understanding of these anomalous oxidation kinetics must encompass both wet and dry oxidants and the strong dependence of the phenomena on the structure of the Si crystal surface. (C) 2002 The Electrochemical Society.