Pulsed metalorganic chemical vapor deposition (MOCVD) of conformal copper seed layers, for the electrodeposition Cu films, has been achieved by an alternating supply of a Cu(I) source and H 2 reactant at the deposition temperatures from 50 to 100 ? C . The Cu thickness increased proportionally to the number of cycles, and the growth rate was in the range from 3.5 to 8.2\AA/cycle , showing the ability to control the nano-scale thickness. As-deposited films show highly smooth surfaces even for films thicker than 100 nm. In addition about a 90% step coverage was obtained inside trenches, with an aspect ratio greater than 30:1. H 2 , introduced as a reactant gas, can play an active role in achieving highly conformal coating, with increased grain sizes.