Pt-doped Ru thin films were prepared by metallorganic chemical vapor deposition (CVD) using cyclopentadienyl-propylcyclopentadienlylruthenium(II) and (trimethyl) methylcyclo pentadienlylplatinum(IV) as the Ru and Pt precursors, respectively. The Pt-doping concentration was varied from 0 to 40 atom %. The Pt-doped Ru films showed a much better thermal stability than the undoped Ru films. The increase in surface roughness and grain growth during postannealing were largely suppressed in the Pt-doped Ru films. As a result, the leakage current density of the Pt-doped Ru (bottom)/Al2O3 /Ru capacitor was almost 100 times smaller than that of the undoped Ru (bottom)/Al2O3 / Ru capacitor at 1 MV/cm after postannealing. (C) 2004 The Electrochemical Society.