Interface strain study of thin Lu2O3/Si using HRBS

Abstract

The interface of thin Lu2O3 on silicon has been studied using high-resolution RBS (HRBS) for samples annealed at different temperatures. Thin rare earth metal oxides are of interest as candidates for next generation transistor gate dielectrics, due to their high-k values allowing for equivalent oxide thickness (EOT) of less than 1nm. Among them, Lu2O3 has been found to have the highest lattice energy and largest band gap, making it a good candidate for an alternative high-k gate dielectric. HRBS depth profiling results have shown the existence of a thin (∼2nm) transitional silicate layer beneath the Lu2O3 films. The thicknesses of the Lu2O3 films were found to be ∼8nm and the films were determined to be non-crystalline. Angular scans were performed across the [110] and [111] axis along planar channels, and clear shifts in the channeling minimum indicate the presence of Si lattice strain at the silicate/Si interface.