A high density plasma dep/etch/dep method of depositing a dielectric film into a gap between adjacent raised structures on a substrate disposed in a substrate processing chamber. The method deposits a first portion of the dielectric film within the gap by forming a high density plasma from a first gaseous mixture flown into the process chamber, etches the deposited first portion of the dielectric film by flowing an etchant gas comprising CxFy, where a ratio of x to y is greater than or equal to 1:2 and then deposits a second portion of the dielectric film over the first portion by forming a high density plasma from a second gaseous mixture flown into the process chamber.