A method of forming tensile stress films for NFET Performance enhancement, comprising the steps of: (a) providing a semiconductor substrate having a gate structure patterned thereon; (b) performing a deposition process to form a first dielectric film overlying the semiconductor substrate and covering the gate structure; (c) performing a curing process on the first dielectric film; (d) successively repeating the step (b) of deposition process and the step (c) of curing process at least once to form at least one second dielectric film on the first dielectric film until the total thickness of the first dielectric film and the at least one second dielectric film reaches a target thickness.