Provided are methods for the deposition of films comprising SiCN. Certain methods involve exposing a substrate surface to a silicon precursor, wherein the silicon precursor is halogenated with Cl, Br or I, and the silicon precursor comprises a halogenated silane, a halogenated carbosilane, an halogenated aminosilane or a halogenated carbo-sillyl amine. Then, the substrate surface can be exposed to a nitrogen-containing plasma or a nitrogen precursor and densification plasma.