PECVD-Ti/TiN[sub x] Barrier with Multilayered Amorphous Structure and High Thermal Stability for Copper Metallization

Ultrathin (10 nm) Ti films with an amorphous structure were deposited by low temperature (<500°C) plasma enhanced chemical vapor deposition (PECVD) using and as reactants. Ammonia plasma was further employed to post-treat the PECVD-Ti barrier layer to improve barrier properties. An amorphous layer forms on the surface of the PECVD-Ti layer after ammonia plasma post-treatment. The resulting films have a multilayered amorphous structure. Furthermore, the effective resistivity of resulting film reduces to 122 μΩ cm. Improved barrier capability against Cu diffusion is found for the barrier layer because the junction diodes retain low leakage current densities even after annealing at 500°C for 1 h. barrier layers present lengthened grain structures to effectively impede Cu diffusion, thus acting as much more effective barriers than are conventional Ti and TiN films.