Influences of pre-oxidation nitrogen implantation and post-oxidation annealing on channel mobility of 4H-SiC MOSFETs

Detailed investigations on the pre-oxidation nitrogen implantation and post-oxidation annealing processes for the improvement of channel mobility and specific on-resistance in 4H-SiC MOSFETs are reported. The results indicate that higher temperature and time for NO nitridation annealing process lead to higher field-effect channel mobility and lower specific on-resistance attributed to the good interface properties of SiC and SiO2 of MOSFETs. Furthermore, more nitrogen implantation energy and dose improved the channel mobility and specific on-resistance due to higher I-d and less fixed charge, traps, and defects at the SiO2/SiC interface. The threshold voltages and blocking performance of MOSFETs are influenced by pre-oxidation nitrogen implantation conditions attributed to changing of counter doping mechanism in the DMOSFET p-well.