A highly tensile dielectric layer is generated on a heat sensitive substrate while not exceeding thermal budget constraints. Cascaded ultraviolet (UV) irradiation is used to produce highly tensile films to be used, for example, in strained NMOS transistor architectures. Successive UV radiation of equal or shorter wavelengths with variable intensity and duration selectively breaks bonds in the Si—N matrix and minimizes shrinkage and film relaxation. Higher tensile stress than a non-cascaded approach may be obtained.