Investigation of reliability of NO nitrided SiC(1100) MOS devices

We systematically investigated the interface properties and reliability of NO nitrided SiC$\left( {1\bar 100} \right)$ m-face MOS devices. Although nitridation at 1250°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.