Temperature-dependent interfacial chemical bonding states and band alignment of HfOxNy∕SiO2∕Si gate stacks

Abstract

Temperature-dependent interfacial chemical bonding states and band alignment of HfOxNy∕SiO2∕Si gate stacks have been investigated by X-ray photoemission spectroscopy (XPS) and spectroscopic ellipsometry (SE). By means of the chemical shifts of Hf 4f, Si 2p, O 1s, and N 1s core-level spectra, it has been found that the chemical stability of the HfOxNy∕SiO2∕Si stacks strongly depends on the annealing temperature. Analysis of temperature-dependent band alignment of HfOxNy∕SiO2∕Si stacks suggests that the valence band offset ΔEv increases slowly from 1.82eV for as-grown film to 2.55eV for annealed film at 700°C; however, the values of conduction band offset ΔEc only demonstrates a slight change in the vicinity of 1.50eV. From the band offset viewpoint, HfOxNy∕SiO2∕Si gate stack could be a promising candidate for high-k gate dielectrics.