A method for forming a mechanically robust dielectric film comprises depositing a dielectric film on a substrate and then inducing a compressive strain in a top surface of the dielectric film to form a compressive strained surface. The compressive strain may be induced using an ion implantation process that bombards the dielectric film with ions that become implanted in the top surface of the dielectric film. The damage caused during ion implantation, as well as the implanted ions themselves, causes an expansion of the top surface which induces a biaxial compressive residual stress, thereby forming a compressive strained surface. The compressive strain reduces the amount of surface flaws present on the top surface, thereby improving the toughness of the dielectric film. In addition, the ion implantation process may modify the plasticity of the top surface and reduce the likelihood of fracture mechanisms based on dislocation pileup for crack initiation.