Enhanced quality of Al₂O₃/SiC gate stack via microwave plasma annealing

The high-quality gate dielectric on silicon carbide (SiC) surface is critical to fabricate high-performance SiC metal–oxide–semiconductor field-effect transistors (MOSFETs). This research employs microwave plasma annealing (MPA) to obtain high-quality Al₂O₃/SiC gate stacks. By designing MPA atmosphere and optimizing the plasma power, the SiC MOS capacitor with a Al₂O₃ dielectric film shows the enhanced performance. The interface state density is reduced by 1 order of magnitude to 6 × 10¹¹ cm⁻²·eV⁻¹, the breakdown electric field is increased, and the voltage shift is effectively suppressed. Besides, the mechanism of MPA process is discussed in terms of the thermal effect and reactant species. X-ray photoelectron spectroscopy (XPS) results unveil oxygen plasma plays the main role. Optimal plasma power during the MPA process results in defect repairs of the first-neighbor Al–O bonding and partial removal of Al–O–H bond from the interface region. This study demonstrates that MPA process is an effective option to realize high-quality dielectric and interface on SiC.