Texture and sheet resistance of Al alloy thin films on Ti and TiN thin films

Ti films prepared by ionized physical vapor deposition (I-PVD) and TiN films prepared by metalorganic chemical vapor deposition (MOCVD) were examined as the underlayers of the Al interconnect films. The crystallographic texture of the Al films and the sheet resistance of the thin-film stacks were investigated at various thicknesses of the Ti or TiN thin film. The sheet resistance of the thin-film stacks was also measured after annealing at 400DGC in an N2 ambient. For the I-PVD Ti underlayer, the excellent texture of the Al (1 1 1) was obtained even on a 5-nm thick Ti film. However, the sheet resistance of the multilayer structure increased after the annealing due to the reaction between Al and Ti. MOCVD TiN layers between the Ti film and the Al film could suppress the AI-Ti reaction without severe degradation of the Al (1 1 1) texture. Excellent texture of the Al film was obtained with thin MOCVD TiN films below 5 nm.