Influence of oxygen content on the structural and electrical characteristics of thin neodymium oxide gate dielectrics

The structural properties and electrical characteristics of thin Nd2 O3 gate oxides were deposited on silicon substrates by reactive rf sputtering. The structural and morphological features of these films were studied, as a function of the growth conditions (three various argon-to-oxygen flow ratios: 205, 1510, and 12.512.5 and temperature from 600 to 800 °C), by x-ray diffraction, atomic force microscopy, and x-ray photoelectron spectroscopy. It is found that Nd2 O3 dielectrics with a 12.512.5 ratio condition annealed at 700 °C exhibit a thinner capacitance equivalent thickness and excellent electrical properties, including the electric breakdown field, the interface trap density, the hysteresis, and frequency dispersion in the capacitance-voltage curves. This condition is suggested to the reduction of the interfacial Si O2 and silicate formation, and the small of surface roughness due to the optimization of oxygen in the metal oxide film.