TiN diffusion barriers for copper metallization

Selected properties concerning a possible Cu/TiN metallization were examined. TiNx films of 40 nm thickness with a N/Ti ratio between 0.59 and 1.01 were deposited on different substrates (HF cleaned Si, Si with native oxide and thermally grown SiO2). The investigated properties are adhesion, stress, microstructure, texture and resistivity, with respect to substrate and environmental effects. Adhesion, stress and texture of the Cu films deposited on TiNx were investigated. The barrier reliability of TiN films is tested. The result of a barrier test performed depends on environmental effects for the Cu/TiN/Si system. TiN is an effective diffusion barrier up to 650 degrees C in hydrogen and 550 degrees C in vacuum by electrical and analytical methods, whereas it fails after 450 degrees C annealing in nitrogen.