Embodiments of the invention describe a method for forming dielectric films for semiconductor devices. The method includes providing a substrate in a process chamber containing a microwave plasma source, introducing into the process chamber a non-metal-containing process gas including a deposition gas having a carbon-nitrogen intermolecular bond, forming a plasma from the process gas, and exposing the substrate to the plasma to deposit carbon-nitrogen-containing film on the substrate. In some embodiments, the carbon-nitrogen-containing film can include a CN film, a CNO film, a Si-doped CN film, or a Si-doped CNO film.