Electrical characteristics of thin cerium oxide film on silicon substrate by reactive DC sputtering

Electrical properties of CeO₂ films prepared by reactive dc sputtering on Si(100) substrate with and without the incorporation of a thin barrier layer were investigated. X-ray diffraction spectra revealed that without the thin barrier layer, single-crystal CeO₂ is formed on Si(100) substrate. At an equivalent oxide thickness of 2.8 nm, CeO₂ films exhibit a leakage current which is four orders of magnitude lower than that of the conventional SiO₂ film at an applied bias of 2 V. Only negligible stress-induced leakage current is observed after high field stressing. The incorporation of the thin silicon nitride buffer layer, however, degraded the crystalline structure of CeO₂, accompanied by deteriorated electrical properties such as leakage current and fixed charges. CeO₂ film without the barrier layer is thus attractive as the high dielectric constant gate insulator for future ultralarge scale integration devices.