The growth kinetics of copper chemical vapor deposition (CVD) on TiN/SiO2/Si substrate were investigated, using Cu(hfac)(vtms) as a precursor with and without iodine assistance. The iodine adsorption on copper enhanced the growth rate and reduced the effective energy barrier. The growth rate increased nearly ten-fold at an iodine surface concentration 4.2 mol%. The rate equation was found to be first order for the Cu(hfac)(vtms) concentration, and the energy barrier decreased as the iodine surface concentration increased. The energy barriers were 16.8 (0.0% I), 9.6 (3.6% I), and 8.6 kcal/mol (4.2% I), as measured based on the reduction in the film thickness along the central line of a mini-chamber at various temperatures. Iodine also played a vital role in the initial growth period; it diminished the incubation time and promoted the horizontal growth of copper nuclei so that they extended and connected with each other to form a flat layer at an earlier stage. The initial flat layer played the role of the seed layer that is usually prepared prior to copper CVD. After the initial growth period, iodine floated out and stayed on the growing copper surface, promoting growth. These beneficial effects enabled void-free copper trench filling to be accomplished on a patterned substrate without a seed layer.