Effects of base oxide in HfSiO/SiO2 high-k gate stacks

Abstract

Electrical characteristics of HfSiO/SiO2 high-k gate stacks have been extensively explored with regard to the effects of base oxide. The flatband voltage shift in N/PMOS capacitors is independent of base oxide thickness, and the dielectric breakdown of the gate stacks is determined by base oxide. In addition, base oxide thickness has a great impact on device performance and charge trapping, presumably due to remote Coulomb scattering (RCS) in the HfSiO bulk layer and direct tunneling through the base oxide. Threshold voltage instability induced by charge trapping will be a major reliability concern for Hf-based high-k gate dielectrics in the future.