A substrate processing apparatus comprising a substrate processing chamber, a gas distribution system operatively coupled to the chamber, a high density plasma power source, a controller operatively coupled to the gas distribution system and the high density plasma power source and a memory coupled to the controller. The memory includes computer instructions embodied in a computer-readable format. The computer instructions comprise (i) instructions that control the gas distribution system to flow a process gas comprising a silane gas, an oxygen-containing source, an inert gas and a hydrogen-containing source that is either molecular hydrogen or a hydride gas that does not include silicon, boron or phosphorus and (ii) instructions that control the high density plasma source to form a plasma having an ion density of at least 1null1011 ions/cm3 from the process gas to deposit the silicon oxide layer over the substrate.