Methods and apparatus for processing a substrate are provided herein. For example, a method includes supplying a vaporized precursor into a processing volume, supplying activated elements including ions and radicals from a remote plasma source, energizing the activated elements using RF source power at a first duty cycle to react with the vaporized precursor to deposit an SiNHx film onto a substrate disposed in the processing volume, supplying a first process gas from the remote plasma source while providing RF bias power at a second duty cycle different from the first duty cycle to the substrate support to convert the SiNHx film to an SiOx film, supplying a process gas mixture formed from a second process gas supplied from the remote plasma source and a third process gas supplied from the gas supply while providing RF bias power at the second duty cycle to the substrate support, and annealing the substrate.