Atomic layer deposition (ALD) and pulsed chemical vapor deposition (CVD) were used to make ruthenium (Ru) thin films from a volatile Ru amidinate precursor, bis(N,N'-di-tert-butylacetamidinato)ruthenium (II) dicarbonyl. The CVD films were grown without any coreactant, while the ALD films used ammonia as a coreactant. The films are fine-grained polycrystalline ruthenium with high purity (< 0.2% impurities). Ru grew as a continuous, electrically conductive, pinhole-free film on tungsten nitride (WN) films even for films as thin as 2 nm. The resistivities of the films match those of pure sputtered ruthenium of the same thickness. Roughness is < 2% of the film thickness. The films are very conformal, with 80% step coverage over holes with high aspect ratios (40:1). This thermal process does not use any oxidant or plasma as a second reagent, thereby avoiding damage to sensitive substrates. The ALD growth rate can reach 1.5 angstrom/cycle at a substrate temperature of 300 degrees C. (c) 2007 The Electrochemical Society.