Pressure dependence of SiO2 growth kinetics and electrical properties on SiC

Dry oxidations between 0.25 and 4 atm at 1150 °C are used to characterize the pressure dependence of the growth kinetics of SiO2 along three orientations of the 4H-SiC polytype. The growth curves are studied using the Deal-Grove model. The extracted linear and parabolic constants are found to scale linearly with the pressure up to 2 atm. However, the data indicate that the (0001) Si-face exhibits a retarded growth rate above 2 atm. It is also found that, like Si, there is a critical oxide thickness below which the linear-parabolic model cannot be applied. This value is found to be between 36 and 40 nm for SiO2 on 4H-SiC, and is apparently independent of the crystal orientation and oxidation pressure. The extracted critical thickness and its properties are similar to what is observed on Si, suggesting that the fast growth regime is dictated by the nature of the oxide. Finally, it is shown that the density of interface states (Dit) on the (0001) Si-face is not reduced by faster oxide growth rates within the monitored energy window.