Influence of oxygen content on the physical and electrical properties of thin yttrium oxide dielectrics deposited by reactive RF sputtering on Si substrates

This paper describes the physical properties and electrical characteristics of thin Y2O3 gate oxides grown on silicon substrates through reactive radio-frequency (RF) sputtering. The structural and morphological features of these films were studied using X-ray diffraction, atomic force microscopy, and X-ray photoelectron spectroscopy. We found that the Y2O3 gate film prepared under an argon-to-oxygen flow ratio of 25:5 and annealed at 700 degrees C exhibited a reduced equivalent oxide thickness, gate leakage current, interfacial density of states, and hysteresis voltage; it also showed an increased breakdown voltage. We attribute this behavior to (1) the optimum oxygen content in the metal oxide film preventing amorphous silica or silicate from forming at the Y2O3/Si interface and (2) the low surface roughness. These materials also exhibit negligible degrees of charge trapping at high electric field stress.