Implementations described herein generally relate to methods for forming dielectric films in high aspect ratio features. In one implementation, a method for forming a silicon oxide layer is provided. A silicon-containing precursor gas is flown into a processing chamber having a substrate having a high aspect ratio feature disposed therein. Then a high frequency plasma is applied to the silicon-containing precursor gas to deposit a silicon-containing layer over the surface of the high aspect ratio feature. The processing chamber is purged to remove by-products from the silicon-containing layer deposition process. An oxygen-containing precursor gas is flown into the processing chamber. A high frequency plasma and a low frequency plasma are applied to the oxygen-containing precursor gas to form the silicon oxide layer.