Growth characterization of rapid thermal oxides

Abstract

The results of a rapid thermal oxide (RTO) growth study involving 200 mm Si wafers oxidized in three different oxidation ambients (O2, N2O, and NO) at two different pressures (100 and 760 Torr), and a wide range of oxidation temperatures (950–1200 °C) and times (0–480 s) are presented in this work. The variable power law is shown to provide an excellent fit to the characteristics. Enhancement in the O2 RTO over furnace oxidation (FO) growth rates, continued growth in N2O RTO, and growth saturation in NO RTO were observed. Anomalies including higher growth rates at a lower pressure in N2O, higher growth rates at lower temperatures and at a lower pressure in NO, as well as higher growth rates in N2O and NO than in O2 were observed. They may be attributable to the competition between the N incorporation rate and the oxide growth rate for predominance, which might in turn be dependent on the temperature, pressure, thickness of and defect density in the initial oxide layer and the amount of N already incorporated. The growth kinetics exhibit Arrhenius relationships. Those for O2 RTO, O2 FO, and low pressure N2O RTO are similar while those for N2O RTO, N2O FO, and NO RTO are different. Our results suggest the oxide thickness range within which the oxidation is reaction limited decreases in the order of O2 RTO, N2O RTO, and NO RTO.