Interfacial and Electrical Characterization of HfO2 Gate Dielectric Film with a Blocking Layer of Al2O3

Abstract

Abstract HfO 2 gate dielectric films with a blocking layer of Al 2 O 3 inserted between HfO 2 layer and Si layer (HfO 2 /Si) were treated with rapid thermal annealing process at 700°C. The interfacial structure and electrical properties were reported. The results of X-ray photoelectron spectroscopy showed that the interfacial layer of SiO x transformed into SiO 2 after the annealing treatment, and Hf-silicates and Hf-silicides were not detected. The results of high-resolution transmission electron microscopy indicated that the interfacial layer was composed of SiO 2 for the annealed film with blocking layer. The results of the electrical measurements indicated that the equivalent oxide thickness decreased to 2.5 nm and the fixed charge density decreased to −4.5×10 11 /cm 2 in comparison with the same thickness of HfO 2 films without the blocking layer. Al 2 O 3 layer could effectively prevent the diffusion of Si into HfO 2 film and improve the interfacial and electrical performance of HfO 2 film.