Photoemission study of energy-band alignment for RuOx/HfO2/Si system

Conductive oxides RuOx as alternative electrode on high-kappa HfO2 gate dielectric have been fabricated by ultrahigh-vacuum sputtering and subsequently oxidized using oxygen plasma. The energy-band alignment for the RuOx/HfO2/Si system and the oxidation-state dependence of barrier height for RuOx contacting to HfO2 dielectrics has been analyzed by x-ray photoemission spectroscopy. The valence- and conduction-band offsets of HfO2/Si are determined to be 3.05+/-0.1 and 1.48+/-0.1 eV, respectively. The barrier heights for the RuOx contacting to HfO2 are oxidation-state dependent, in the range of 1.95-2.73 eV. (C) 2004 American Institute of Physics.