Interfacial structures and electrical properties of HfAl_2O_5 gate dielectric film annealed with a Ti capping layer

摘要

HfAl_2O_5 gate dielectric film with an O-gettering Ti capping layer treated with rapid thermal annealing process and its interfacial structure and electrical properties were reported. X-ray reflectivity measurements and x-ray photoelectron spectroscopy suggested that the interfacial layers were composed of a 0.5 nm HfAlSiO layer and a 1.5 nm Si_x(SiO_2)_(1-x)(x < 1) layer for the as-deposited film. However, for the annealed film, HfAlSiO layer was not found and the 1.5 nm Si_x(SiO_2)_(1-x) transformed to a 1 nm SiO_2. The electrical measurements indicated that the equivalent oxide thickness decreased to 2.9 nm, and the leakage current was only 70 μA/cm~2 at the gate bias of 10 MV/cm for the annealed film.