Fabricating copper interconnects by displacement technology for ULSI

In this paper, the process of fabricating Cu layers by displacement reaction is demonstrated. In our experiments, Ti was used and displaced in the chemical reaction to form copper films. TiN was also adopted to improve the adhesion between the copper and the dielectric layer. The effects of the process recipe on the structure and reliability of the Cu lines were studied. The obtained average electrical resistivity of the Cu films was 2.04 μΩ-cm after thermal annealing and it was 3.18 μΩ-cm for samples grown from a less-oxygen-containing solution. The study of the reliability showed that the activation energy of the copper interconnects was 0.92 e V, which is very close to the result for the Cu films grown by sputtering.