Annealing Dependence of Negative Bias Temperature Instability (NBTI) in 4H-SiC MOSFETs

Abstract

In this work, we report on the improvement of negative bias temperature instability (NBTI) in 4H-SiC MOS-FETs by annealing process in NO (Device B), compared to in N2O (Device A). The V-th shift and interface properties of SiC MOSFETs under negative bias stress were investigated. The Device A and B have Delta V-th values of 0.51 V and 0.09 V, respectively. From the time dependences, we applied a two component model that considers nitrogen(N)-related traps. The relatively small value of Delta V-th is indicative of the decrease in the oxide traps and activation of nitrogen-related traps. The N-it of the Device B was decreased about 17 times compared to Device A. These results indicate to the reduction of the N-related defects into the oxide network. Controlling of nitrogen in SiO2 is important for the long-term V-th stability of SiC-MOSFETs under NBT stress.