Ge Incorporation in HfO2 Dielectric Deposited on Ge Substrate during Dry/Wet Thermal Annealing

Ge incorporation in HfO2 thin films deposited on Ge substrates by electron-beam evaporation was investigated during dry/wet thermal annealing in N-2 ambient. The structural and chemical changes and the electrical properties of HfO2 were monitored by angle-resolved X-ray photoemission spectroscopy and current-voltage characteristics. Considerable Ge incorporation as GeOx in HfO2 on the Ge substrate during the deposition and annealing processes led to the formation of germanate of hafnium and the deterioration of the leakage current after thermal annealing. The oxidation degree of the incorporated GeOx increased with wet annealing time. It was indicated that Ge incorporated in HfO2 came from Ge upward diffusion from the Ge substrate and the GeO evaporation from the uncovered back side of the Ge substrate. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3369964] All rights reserved.