摘要
Ultrathin (10 nm) Ti films with an amorphous structure were deposited by low temperature (<500°C) plasma enhanced chemical vapor deposition (PECVD) using TiCl <sub>4</sub> and H <sub>2</sub> as reactants. Ammonia plasma was further employed to post-treat the PECVD-Ti barrier layer to improve barrier properties. An amorphous TiN <sub>x</sub> layer forms on the surface of the PECVD-Ti layer after ammonia plasma post-treatment. The resulting films have a multilayered amorphous Ti/TiN <sub>x</sub> structure. Furthermore, the effective resistivity of resulting Ti/TiN <sub>x</sub> film reduces to 122 μΩ cm. Improved barrier capability against Cu diffusion is found for the Ti/TiN <sub>x</sub> barrier layer because the Cu/TiN <sub>x</sub> /Ti/n <sup>+</sup> -p junction diodes retain low leakage current densities even after annealing at 500°C for 1 h. Ti/TiN <sub>x</sub> 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.