Chemical Bonding, Interfaces, and Defects in Hafnium Oxide∕Germanium Oxynitride Gate Stacks on Ge(100)

Abstract

Correlations among interface properties and chemical bonding characteristics in HfO2∕GeOxNy∕GeHfO2∕GeOxNy∕Ge metal–insulator–semiconductor stacks were investigated using in situ remote nitridation of the Ge(100) surface prior to HfO2HfO2 atomic layer deposition. Ultrathin (∼1.1nm)(∼1.1nm) , thermally stable, and aqueous etch-resistant GeOxNyGeOxNy interface layers that exhibited Ge core-level photoelectron spectra similar to stoichiometric Ge3N4Ge3N4 were synthesized. To evaluate GeOxNy∕GeGeOxNy∕Ge interface defects, the density of interface states (Dit)(Dit) was extracted by the conductance method across the bandgap. Forming gas annealed (FGA) samples exhibited substantially lower DitDit (∼1×1012cm−2eV−1)(∼1×1012cm−2eV−1) than did high-vacuum-annealed and inert gas anneal samples (∼1×1013cm−2eV−1)(∼1×1013cm−2eV−1) . Germanium core-level photoelectron spectra from similar FGA-treated samples detected out-diffusion of germanium oxide to the HfO2HfO2 film surface and apparent modification of chemical bonding at the GeOxNy∕GeGeOxNy∕Ge interface which is related to the reduced DitDit .