Obtaining low resistivity (∼100 μΩ cm) TiN films by plasma enhanced atomic layer deposition using a metalorganic precursor

Low resistivity (∼100 μΩ cm) titanium nitride (TiN) films were obtained by plasma enhanced atomic layer deposition using tetrakis(dimethylamido)titanium and a nitrogen/argon plasma mixture. The impact of process parameters on film crystallinity, oxygen contamination, and electrical resistivity was studied systematically. A low background pressure during the plasma half-cycle was critical for obtaining low resistivity. The low resistivity films were highly crystalline, having (001) oriented columnar grains. Oxygen and carbon content was about 3% and 2%, respectively. The role of argon plasma in film properties is discussed. Plasma damage to thin dielectric films beneath the TiN layer was minimized by the low-pressure process. The authors suggest that electron scattering at grain boundaries is the dominant mechanism which determines the resistivity of the TiN films, thus obtaining large columnar grains is the key to obtaining low film resistivity.