The chemical vapor deposition of Ru films from (2,4-dimethylpentadienyl)(ethylcyclopentadienyl)Ru and O(2) was carried out both with and without CH(3)I addition. X-ray photoelectron spectroscopy indicates that the addition of CH(3)I does not significantly increase the amount of carbon in the films. Adsorbed iodine on the growing film surface results in denser, more uniform nucleation and smaller-grained, smoother films. The root-mean-square roughness of 60 nm films decreased from 8.42 to 5.62 nm for no CH(3)I and CH(3)I addition, respectively. Adsorbed iodine segregates through the films to the surface during growth, resulting in a continuously depressed deposition rate. The adsorbed iodine blocks oxygen dissociation sites, reducing the oxygen supply available to decompose the ligands of the Ru precursor. (C) 2009 Elsevier B.V. All rights reserved.