A method of processing a substrate including depositing a low dielectric constant film comprising silicon, carbon, and oxygen on the substrate and depositing an oxide rich cap on the low dielectric constant film is provided. The low dielectric constant film is deposited in the presence of low frequency RF power from a gas mixture including an organosilicon compound and an oxidizing gas. The low frequency RF power is terminated after the deposition of the low dielectric constant film. The oxide rich cap is deposited on the low dielectric constant film in the absence of low frequency RF power from another gas mixture including the organosilicon compound and the oxidizing gas used to deposit the low dielectric constant film.