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.

Comparative study of mechanical stress-induced flat-band voltage change in MOS capacitor and threshold voltage change in MOSFET fabricated on 4H-SiC (0001)

“…The conduction band offset between SiC and SiO 2 should induce change as well in this case. The other possible factor is a change in near-interface fixed or trapped charge density, 28) for non-zero V fb originates from fixed charges, and it is possible that their unstable density at the nitridated interface 29) is affected by mechanical stress. Both assumptions will be further studied quantitatively in future work.…”