Methods are described for forming and curing a flowable silicon-carbon-and-nitrogen-containing layer on a semiconductor substrate. The silicon and carbon constituents may come from a silicon and carbon containing precursor while the nitrogen may come from a nitrogen-containing precursor that has been activated to speed the reaction of the nitrogen with the silicon-and-carbon-containing precursor at lower deposition chamber temperatures. The initially-flowable silicon-carbon-and-nitrogen-containing layer is treated to remove components which enabled the flowability, but are no longer needed after deposition. Removal of the components increases etch resistance in order to allow the gapfill silicon-carbon-and-nitrogen-containing layer to remain intact during subsequent processing. The treatments have been found to decrease the evolution of properties of the film upon exposure to atmosphere.