Effect of varying oxidation parameters on the generation of C-dangling bond centers in oxidized SiC

SiC is perhaps the most appropriate material to replace Si in power-metal-oxide-semiconductor-field-effect-transistors (MOSFETs), because, unlike the other wide band-gap semiconductors, SiC can be thermally oxidized similarly to Si to form a SiO2 insulating layer. In our studies of oxidized SiC, we have used electron paramagnetic resonance (EPR) to identify C-dangling bonds generated by hydrogen release from C-H bonds. While hydrogen's effect on SiC-based MOSFETs is uncertain, studies of Si-based MOSFETs indicate that it is important to minimize hydrogen in MOS structures. To examine the role of hydrogen, we have studied the effects of SiC/SiO2 fabrication on the density of C-related centers, which are made EPR active by a dry heat-treatment. Here we examine the starting and ending procedures of our oxidation routine. The parameter that appears to have the greatest effect on center density is the ending step of our oxidation procedure. For example, samples that were removed from the furnace in flowing O-2 produced the smallest concentration of centers after dry heat-treatment. We report on the details of these experiments and use our results to suggest an oxidation procedure that limits center production.