A nitrided oxide layer on a silicon carbide layer is processed by annealing the nitrided oxide layer in a substantially oxygen-free nitrogen containing ambient. The anneal may be carried out at a temperature of greater than about 900 C., for example, a temperature of about 1100 C., a temperature of about 1200 C. or a temperature of about 1300 C. Annealing the nitrided oxide layer may be carried out at a pressure of less than about 1 atmosphere, for example, at a pressure of from about 0.01 to about 1 atm or, in particular, at a pressure of about 0.2 atm. The nitrided oxide layer may be an oxide layer that is grown in a N₂O and/or NO containing ambient, that is annealed in a N₂O and/or NO containing ambient or that is grown and annealed in a N₂O and/or NO containing ambient.