Catalyst-enhanced chemical vapor deposition (CECVD) of copper (Cu) on ruthenium (Ru) layer using iodine as a catalytic-surfactant has been studied for the seedless Cu superfilling of submicron features of trenches and via holes. Hydrogen improved adsorption of iodine by assisting hydrogenation reaction when diiodomethane (CH2I2) vapor was provided onto Ru surface in hydrogen ambient. The iodine adatoms on Ru layer also showed catalytic-surfactant effect on the subsequent CVD of Cu as well as on Cu seed layer. As a result, the superfilling of Cu on submicrometer features was achieved on Ru glue layer without Cu seed layer. (C) 2005 The Electrochemical Society.