Semiconductor processing methods are described for forming UV-treated, low-κ dielectric films. The methods may include flowing deposition precursors into a substrate processing region of a semiconductor processing chamber. The deposition precursors may include a silicon-and-carbon-containing precursor. The methods may further include generating a deposition plasma from the deposition precursors within the substrate processing region, and depositing a silicon-and-carbon-containing material on the substrate from plasma effluents of the deposition plasma. The as-deposited silicon-and-carbon-containing material may be characterized by greater than or about 5% hydrocarbon groups. The methods may still further include exposing the deposited silicon-and-carbon-containing material to ultraviolet light. The exposed silicon-and-carbon-containing material may be characterized by less than or about 2% hydrocarbon groups.