Embodiments of the present invention provide methods, apparatuses, and devices related to chemical vapor deposition of silicon oxide. In one embodiment, a single-step deposition process is used to efficiently form a silicon oxide layer exhibiting high conformality and favorable gap-filling properties. During a pre-deposition gas flow stabilization phase and an initial deposition stage, a relatively low ratio of silicon-containing gas:oxidant deposition gas is flowed, resulting in formation of highly conformal silicon oxide at relatively slow rates. Over the course of the deposition process step, the ratio of silicon-containing gas:oxidant gas is increased, resulting in formation of less-conformal oxide material at relatively rapid rates during later stages of the deposition process step.