In this study, Y₂O₃ thin films were deposited on Si(100) wafers using an RF sputtering system with a Y₂O₃ target. The Y₂O₃ thin film was confirmed to have a thickness of 227 nm/min and a uniformity of 1.34% at a substrate temperature of 400℃. All samples were annealed at 600, 800, and 1,000℃ for 1 hour in an O₂ gas atmosphere using the furnace. The analysis of the XRD patterns revealed that the peak intensity increased with annealing up to 800℃, but decreased when the annealing temperature was raised to 1,000℃. The XPS analysis confirmed the onset of crystallization at 800℃, in agreement with the trends observed in the XRD results. According to the AFM results, the surface became slightly smoother after heat treatment, as indicated by a reduced RMS roughness of approximately 1.792 nm.