Investigation of the Interface Quality and Reliability of 4H-SiC MOS Structure with NO and Forming Gas Annealing Treatment

Effects of NO and forming gas annealing treatment on the interface quality and reliability of 4H-SiC MOS were systematically studied by low temperature conductance measurements in combination with time-zero dielectric breakdown and time-dependent dielectric breakdown methods. The interface trap density (Dit) showed no obvious reduction after forming gas annealing, and the values of Dit decreased significantly after combined NO and forming gas annealing treatment. The F-N barrier height, electric field to breakdown (Ebd) and charge to breakdown (Qbd) of the MOS structure increased from 2.42 eV, 10 MV/cm, 1mC/cm2 to 2.62 eV, 10.7 MV/cm, 78mC/cm2 after forming gas annealing. The values of F-N barrier height, Ebd and Qbd for MOS capacitors with combined NO and forming gas annealing treatment are 2.69 eV, 10.2 MV/cm, and 24mC/cm2. These results suggest that forming gas annealing is more effective in reliability improvement. While when considering the interface trap density, it seems that combined NO and forming gas annealing treatment is a better choice.