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.