Characterization of rare earth oxides based MOSFET gate stacks prepared by metal-organic chemical vapour deposition

We have prepared rare earth oxides based MOSFET gate stacks using metal-organic chemical vapour deposition, MOCVD. Gd2O3, La2O3, Nd2O3 and Pr6O11 films with thickness 3–20 nm were deposited on silicon substrate at 500 °C. The films were characterized by X-ray diffraction, X-ray reflectivity, transmission electron microscopy and X-ray photoelectron spectroscopy. As a next step, Ru films were grown on the dielectric films at 300 °C as a gate electrode. Electrical characterization of the MOS structures was performed by capacitance–voltage measurements. The structures annealed at 430 °C in forming gas (90% N2+10% H2) exhibited dielectric constant ranging from 12 to 14. Typically, the films showed high values of fixed oxide charge density, Nox∼1012cm-2. Fixed oxide charges can be decreased by post-deposition annealing in forming gas and in oxygen.