Characterization of Conductive RuO_2 Thin Film as Bottom electrodes for Ferroelectric Thin Films

摘要

Ruthenium Oxide (RuO_2) thin films were prepared on silicon substrates by solution chemistry technique. X-ray Diffraction (XRD), Atomic Force Microscopy (AFM), micro-Raman, X-ray photoelectron spectroscopy (XPS), and four probe Van-der-paw technique were used for the film characterization. X-ray analysis shows a rutile structure in these films. The films annealed at 700 °C showed lowest resistivity of 29 * 10~5 ohm-cm. The presence of E_g, A_(1g), and B_(2g) modes is consistent with the Raman spectrum of rutile phase. These modes as well as additional unidentified band at about 477 cm~(-1) were investigated by temperature dependent Raman studies. Based on the result, band at 477 cm~(-1) that disappears above 370 K is attributed to hydrated RuO_2 present in the films. XPS analysis show stoichiometric rutile RuO_2 present in the films. Small concentrations of RuCl_3, RuO_3 and hydrated RuO_2 were also detected. Pb_(0.9)La_(0.15)TiO_3 (PLT15) thin films were deposited on RuO_2/Si substrates and characterized for its ferroelectric properties to demonstrate that solution deposition technique offers an alternative approach for preparing high quality RuO_2 bottom electrodes.