Effects of oxygen content and postdeposition annealing on the physical and electrical properties of thin Sm2O3 gate dielectrics

In this paper, we describe the physical properties and electrical characteristics of thin Sm₂O₃ dielectric films deposited on Si (100) by means of rf reactive 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: 10/15, 15/10 and 20/5, and temperature from 600 to 800 °C), by x-ray diffraction, atomic force microscopy, and x-ray photoelectron spectroscopy. It is found that Sm₂O₃ dielectric prepared under 15/10 flow ratio and annealed at 700 °C exhibits a thinner capacitance equivalent thickness and excellent electrical properties, including the interface trap density, the hysteresis and frequency dispersion in the capacitance-voltage curves. This condition is attributed to the reduction of the interfacial SiO₂ and silicate formation, and the small of surface roughness due to the optimization of oxygen in the Sm₂O₃ film.