Rapid thermal processing is reported to be capable of improving film properties. In this study, the effects of rapid thermal annealing (RTA) on rapid-thermal-annealed radio-frequency-sputtered silicon oxide films and hence on excimer laser-induced ripple structures at the silicon dioxide/silicon interface are investigated. It is found that the RTA of the oxide film by increasing either annealing temperature or annealing time can enhance the ripple growth, but does not change the topography of ripple structure. The ellipsometric measurements indicate that the optical constants of the film, and hence the calculated film density increase with increasing either annealing temperature or annealing time. The increase in film density is balanced by the decrease in the corresponding film thickness. Our analytical model predicts that the increase in ripple period is a result of enhanced energy absorption caused by the decrease in equivalent reflectivity of SiO2/Si after RTA. The calculation is identified to be consistent with the experiment.