Ru films were produced by atomic layer deposition (ALD) with an alternating supply of bis(ethylcyclopentadienyl)ruthenium (Ru(EtCp)(2)) and ozone at deposition temperatures of 225-275 degrees C. Ozone acted as an effective reactant for Ru(EtCp)(2). The Ru film thicknesses formed during one cycle were saturated at relatively high values of 0.09-0.12 nm/cycle depending on the deposition temperatures, and their resistivities were about 16 mu Omega cm. Moreover, a reduced nucleation delay was found for Ru ALD using ozone when compared to Ru ALD using oxygen gas. The amount of oxygen impurity incorporated into the Ru films was less than 1 at%, as determined by Auger electron spectroscopy. The interfacial adhesion property between Ru films prepared via ALD using ozone (ozone-Ru) and ZrO2 was good and 80% step coverage was achieved on a 3-D structure with a very high aspect ratio of 16:1, making them suitable for use as a top electrode material.