Unexpected fixed charge generation by an additional annealing after interface nitridation processes at the SiO2/4H-SiC (0001) interfaces

Abstract

We clarified that the additional annealing process after nitric oxide post-oxidation annealing on SiO2/4H-SiC stack is responsible for the generation of the positive fixed charges in metal-oxide-semiconductor capacitors, though we could not detect deterioration of interface state density. The generation of fixed charge was suggested to occur during the annealing process of the nitrided-interface structure. To avoid this phenomenon, a moderate process temperature should be employed in the post-nitridation annealing processes, such as post-metallization annealing.