Si/SiO 2 films were fabricated by alternative sputtering silicon and SiO 2 targets following by rapid-thermal-annealing (RTA) and furnace-annealing (FA) treatment. After RTA treatment, the extent of crystallization and the density of Si clusters increase with sputtering rate, while the size distributions of clusters obtained at low and high sputtering rates are more uniform than that at the mid-sputtering rate. Initial clusters and structure defects in the as-deposited films combine with atomic diffusion during RTA to determine the size distribution and density of Si clusters. During the FA process, excessive Si atoms can precipitate by either adhering to the existent Si clusters or congregating into new clusters.