A plasma enhanced chemical vapor deposition process for producing a fluorinated silicon nitride film on a substrate is disclosed. The process utilizes a mixture of silane, perfluorosilane and nitrogen to produce films of high conformality and stability. The silane and perfluorosilane in the mixture are in a ratio of 0.05 to 1 on a volume basis. The preferred silane is SiH.sub.4 and the preferred perfluorosilane is SiF.sub.4. Films prepared by the process are disclosed and their properties are described.