Effects of nitridation and annealing on interface properties of thermally oxidized SiO2/SiC metal-oxide-semiconductor system

The effects of N2O nitridation and subsequent annealing in different condit ions on thermally oxidized n-type 6H-silicon carbide (SiC) metal-oxide-semi conductor (MOS) interface properties were investigated. Influence of high-f ield stress on the MOS system was also studied. The nitrided device anneale d in dry or wet O-2 is found to have lower interface-state density compared to the device annealed in N-2 because the reoxidation can reduce nitridati on-induced interface damage. Furthermore, significantly less shift of flatb and voltage during high-field stress for all nitrided devices indicates muc h better oxide reliability by replacing strained Si-O bonds with stronger S i-N bonds during nitridation. This is further supported by the fact that an nealing of the nitrided device in dry or wet oxygen slightly reduces the ro bustness of the oxide. In summary, the O-2-annealing conditions have to be optimized to deliver a proper tradoff between interface quality and reliabi lity. (C) 2000 American Institute of Physics. [S0003-6951(00)01025-1].