Electrical, optical and structural characterization of high-k dielectric ZrO2 thin films deposited by the pyrosol technique

High-k dielectric zirconium oxide (ZrO(2)) thin films have been deposited on silicon substrates at temperatures from 400 to 600degreesC using the spray pyrolysis technique. The films were deposited from two spraying solution concentrations (0.033 and 0.066 M) of zirconium acetylacetonate dissolved in N,N-dimethylformamide. These films were stoichiometric, transparent and with a very low surface roughness (5-40 Angstrom). The refractive index of these films was of the order of that obtained for a bulk material (2.12). Films deposited with high molar concentration presented the best electrical characteristic, have a dielectric constant in the range 12.5-17.5, depending on the deposition temperature, and can stand electric fields up to 3 MV cm(-1) without observing destructive dielectric breakdown. Transmission electron microscopy measurements, indicate that the films consist of nano-crystallites of the tetragonal ZrO(2) crystalline phase embedded into an amorphous matrix. Infrared spectroscopy measurements of the films show peaks associated with ZrO(2) and a peak related to silicon dioxide (SiO(2)). The analysis of spectroscopic ellipsometry measurements on these films indicates the existence of a layer at the ZrO(2)/Si interface composed of SiO(2) as well as ZrO(2) and crystalline silicon. (C) 2004 Kluwer Academic Publishers.