A chemical vapor deposition reaction system converts a reactant precursor, which includes the metal Ruthenium, to a vapor during a chemical reaction in order to deposit the metal on a semiconductor wafer. The reactant precursor is Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)(1,5-cyclooctadiene)Ru. An energy source provides energy to the reaction chamber to induce the chemical reaction. A controllable metering system alternatively supplies the precursor and oxygen to the reaction chamber. The precursor is supplied into the reaction chamber during a first phase and the oxygen is supplied into the reaction chamber during a second phase, which is non-overlapping with the first phase. A first pump/valve provides the precursor to the reaction chamber, and a second pump/valve provides the oxygen to the reaction chamber, each in response to a controller. The Ruthenium is selectively deposited on oxide sites patterned on a surface of the semiconductor wafer.