Investigation of reliability of NO nitrided SiC(1(1)over-bar00) MOS devices

We systematically investigated the interface properties and reliability of NO nitrided SiC(1 (1) over bar 00) m-face MOS devices. Although nitridation at 1250 degrees C improved the capacitance-voltage characteristics (i.e., flat-band voltage (V-FB) shift and hysteresis), the nitridation reduced the onset field of the Fowler-Nordheim current by about 1 MVcm(-1), causing a higher oxide leakage. Furthermore, the nitrided samples exhibited pronounced V-FB shifts in response to both electron and hole injection under a high stress field condition (oxide field: +/- 7-8 MVcm(-1)). In addition, when the bias stress condition was chosen on the basis of leakage current density instead of the oxide field, the V-FB shifts became similar for samples with different nitridation durations. This indicates that the observed V-FB shift is mainly caused by the carrier trapping into pre-existing traps. Our results clearly indicate the drawbacks of nitridation for m-face MOS devices in terms of oxide leakage and V-FB instability.