Influences of high-temperature annealing on atomic layer deposited Al₂O₃/4H-SiC

High-temperature annealing of atomic layer deposition (ALD) of Al₂O₃ films on 4H-SiC in O₂ atmosphere is studied with temperature ranging from 800℃ to 1000℃. It is observed that the surface morphology of Al₂O₃ films annealed at 800℃ and 900℃ is pretty good, while the surface of the sample annealed at 1000℃ becomes bumpy. Grazing incidence X-ray diffraction (GIXRD) measurements demonstrate that the as-grown films are amorphous and begin to crystallize at 900℃. Furthermore, C-V measurements exhibit improved interface characterization after annealing, especially for samples annealed at 900℃ and 1000℃. It is indicated that high-temperature annealing in O₂ atmosphere can improve the interface of Al₂O₃/SiC and annealing at 900℃ would be an optimum condition for surface morphology, dielectric quality, and interface states.