Preparation and Properties of Thin HfO2 Films

HfO2 layers were grown on silicon by metalorganic chemical vapor deposition using (C5H5)2Hf(CH3)2, (C5H5)2Hf(N(C2H5)2)2, and Hf(dpm)4 as volatile precursors and were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, and IR spectroscopy. The films were shown to consist of monoclinic HfO2 and to contain hafnium silicide and silicate at the HfO2/Si interface. The presence of hafnium silicide was attributed to oxygen deficiency produced by argon ion milling. Hafnium silicate was formed as a result of the reaction between hafnium and silicon oxides during annealing. Current-voltage and capacitance-voltage measurements on Al/HfO2/Si test structures were used to determine the dielectric permittivity and electrical resistivity of the films: ɛ = 15–20, ρ ∼ 1015 cm.