Improved Stability of 4H-SiC MOS Device Properties by Combination of NO and POCl sub(3) Annealing

Effects of combination of NO and POCl sub(3) annealing on electrical properties and their stability of 4H-SiC MOS capacitors and MOSFETs were investigated. Channel mobility of MOSFETs processed with both NO and POCl sub(3) annealing did not exceed that of POCl sub(3) annealed MOSFETs. As for the stability of flat-band voltage and threshold voltage using a constant field stress test, the combined annealed sample indicated very stable characteristics compared with single annealed devices with NO or POCl sub(3). The reason for obtaining stable electrical properties is discussed based on nitridation and phosphorization effects at the interface.