Ruthenium-titanium nitride (Ru-TiN) thin films were grown by plasma-enhanced atomic layer deposition (PEALD) at a growth temperature of 200 degrees C. For the Ru - TiN PEALD, Ru and TiN were sequentially deposited to intermix TiN with Ru. The composition of Ru - TiN films was controlled by changing the number of deposition cycles allocated to Ru, while the number of deposition cycles for TiN was fixed to one cycle. The microstructures of Ru - TiN films changed from polycrystalline to amorphous, as the intermixing ratio of Ru increased in the deposited Ru - TiN films. The resistivity of the Ru - TiN film was abruptly increased by adding Ru at the first stage, but after showing a peak resistivity, it decreased with the intermixing ratio of Ru in the films. Especially, the film of Ru-0.67 -(TiN)(0.33) showed an electrical resistivity of 190 mu Omega cm. As a Cu diffusion barrier layer, amorphous Ru - TiN films showed a superior copper diffusion barrier property to TiN or Ru itself, which had a polycrystalline structure. Moreover, Ru - TiN films showed a good adhesion to both chemical vapor deposition copper and an underlayer of SiO2. (C) 2006 The Electrochemical Society.