Stoichiometry of the ALD-Al2O3/4H-SiC interface by synchrotron-based XPS

The interface of Al2O3 with 4H-SiC is investigated with synchrotron-based high-resolution x-ray photoelectron spectroscopy to clarify the effect of post-dielectric deposition annealing processes (rapid thermal annealing (RTA) and furnace annealing (FA)) involved in device fabrication. Our results show that post-deposition annealing of Al2O3/4H-SiC up to 1100 degrees C forms a thin interfacial layer of SiO2 between Al2O3 and SiC, which possibly improves the dielectric properties of the system by reducing oxide charges and near-interface traps. Moreover, the formation of SiO2 at the interface gives additional band offset to the dielectric system. We have also observed that the RTA and FA processes have similar results at a high temperature of 1100 degrees C. Therefore, we propose that high-temperature post-oxide (Al2O3) deposition annealing of up to 1100 degrees C may be used in device processing, which can improve overall dielectric properties and consequently the device performance.