STRUCTURE, COMPOSITION AND ORDER AT INTERFACES OF CRYSTALLINE OXIDES AND OTHER HIGH-K MATERIALS ON SILICON

摘要

High-resolution medium energy ion scattering (MEIS) was used to investigate structure, composition and defects in amorphous and crystalline oxides, and their interface with silicon. Isotopic oxygen reactions were examined in several model high-κ systems, including Hf and Ce oxides, silicates and nitrided silicates as a function of composition, crystallinity and post-deposition annealing conditions. Our results show that for post-growth oxidation of Hf-based films there was extensive O exchange throughout the film which could be suppressed by the addition of SiO_2. Under our growth conditions, there was no measurable interfacial SiO_2 formation. In contrast Ce silicates exhibit rapid interface growth under similar oxygen exposures. Epitaxial SrTiO_3 and Sc_2O_3 films grown by MBE on Si were studied in different channeling geometries. We show that diffusion of Ti and O during SrTiO_3 film growth on Si (001) results in substitution of thin interfacial Sr silicide layer used at the initial stages of growth by Ti- or Sr-silicate like interfacial layers depending on the growth condition.