Copper is applied to integrated circuit substrates, for example, by chemical vapor deposition using a copper precursor of a dimethoxymethylvinylsilane (dmomvs), or a methoxydimethylvinylsilane (modmvs) silylolefin ligand bonded to (hfac)Cu. The improved copper complex-ligand bond helps ensure that the ligand separates from the (hfac)Cu complex at consistent temperatures when Cu is to be deposited. Water vapor may be added to the precursor to improve the conductivity of the deposited Cu, and additional silylolefins, hexafluoroacetylacetone (H-hfac), and water may be used separately or in combination to enhance deposition rate, conductivity, and precursor stability.