Methods are provided for depositing a silicon oxide film on a substrate disposed in a substrate processing chamber. The substrate has a gap formed between adjacent raised surfaces. A process gas having a silicon-containing gas, an oxygen-containing gas, and a fluent gas is flowed into the substrate processing chamber. The fluent gas is introduced into the substrate processing chamber at a flow rate of at least 500 sccm. A plasma is formed having an ion density of at least 10.sup.11 ions/cm.sup.3 from the process gas to deposit a first portion of the silicon oxide film over the substrate and into the gap. Thereafter, the deposited first portion is exposed to an oxygen plasma having at least 10.sup.11 ions/cm.sup.3. Thereafter, a second portion of the silicon oxide film is deposited over the substrate and into the gap.