Methods are described for a cyclical deposition and curing process. More particularly, the implementations described herein provide a cyclic sequential deposition and curing process for filling features formed on a substrate. Features are filled to ensure electrical isolation of features in integrated circuits formed on a substrate. The processes described herein use flowable film deposition processes that have been effective in reducing voids or seams produced in features formed on a substrate. However, conventional gap-filling methods using flowable films typically contain dielectric materials that have undesirable physical and electrical properties. In particular, film density is not uniform, film dielectric constant varies across the film thickness, film stability is not ideal, film refractive index is inconsistent, and resistance to dilute hydrofluoric acid (DHF) is not ideal in conventional flowable films. The cyclic sequential deposition and curing processes address the issues described herein to create films with higher quality and increased lifetime.