A semiconductor method of manufacturing involving low-k dielectrics is provided. The method includes depositing a hydrocarbon of the general composition C.sub.xH.sub.y on the surface of a low-k dielectric. The hydrocarbon layer is deposited by reacting a precursor material, preferably C.sub.2H.sub.4 or (CH.sub.3).sub.2CHC.sub.6H.sub.6CH.sub.3, using a PECVD process. In accordance with embodiments of this invention, carbon diffuses into the low-k dielectric, thereby reducing low-k dielectric damage caused by plasma processing or etching. Other embodiments comprise a semiconductor device having a low-k dielectric, wherein the low-k dielectric has carbon-adjusted dielectric region adjacent a trench sidewall and a bulk dielectric region. In preferred embodiments, the carbon-adjusted dielectric region has a carbon concentration not more than about 5% less than in the bulk dielectric region.