The selectivity of copper deposition from copper (II) bis‐hexafluoroacetylacetonate on SiO2patterned with a platinum seeding layer is studied as a function of the reagent gas mixture. On platinum, the copper film growth rate increases with the amount of water vapor in the gas flow, and is independent of the chemical nature of the carrier gas used (H2or He). The selectivity of the copper deposition is significantly improved when using He rather than H2as carrier gas, especially at high water vapor concentrations where rapid film growth can be obtained.