Oxidation kinetics of ion-amorphized (0001) 6H-SiC: Competition between oxidation and recrystallization processes

The wet oxidation of (0001) Si face 6H-SiC preamorphized by Ar+ implantation has been investigated in the temperature range between 750 and 950 degrees C. Electron microscopy analysis has been performed to obtain information on the evolution of the amorphous layer during the oxidation process. The oxidation rate of the amorphous substrate is linear in time and assumes the value V-Ox(alpha)=3.8x10(7) exp(-1.6/kT) nm/min. Due to the concomitant oxidation and recrystallization processes occurring at the two opposite faces of the amorphous layer, this expression is valid up to about 910 degrees C for amorphous layer thickness of a few hundreds nanometer and processing time of a few tens of minutes. At higher temperatures, our oxidation data support the existence of a sudden increasing of the recrystallization that strongly reduces the time of surviving of the amorphous region and, consequently, the oxide thickness. The procedure to determine, for any fixed amorphous thickness, the most suitable experimental conditions giving rise to the maximum oxide thickness (i.e., the temperature at which corresponds the shortest oxidation time), preserving at the same time the flatness of the oxidized surface, is reported.