Electrical and physical properties of 4H-SiC MOS interface with electron cyclotron resonance microwave nitrogen plasma post-oxidation annealing

An electron cyclotron resonance microwave nitrogen plasma post-oxidation annealing process was proposed to passivate the 4H-SiC MOS interface. The effects of this process on the electrical and physical properties of SiC MOS interface were investigated by current–voltage, capacitance–voltage, secondary ion mass spectrometry, and X-ray photoelectron spectroscopy measurements. By controlling the annealing period, this process could significantly reduce the density of interface traps (Dit) in the entire upper half of SiC band gap without degrading the oxide insulating properties. A 10-min annealing at 600 °C produces the best result. The incorporated nitrogen, which is distributed throughout bulk SiO2 and SiO2/SiC interface, could reduce the content of SiOxCy and carbon clusters by forming some deep-level Si–N and C–N bonds. These results illustrate the physical modifications of SiC MOS interface induced by this process and explain the possible mechanism responsible for the observed reduction in Dit in different energy ranges.