Investigation on multilayered chemical vapor deposited Ti/TiN films as the diffusion barriers in Cu and Al metallization

A novel multilayered chemical vapor deposition (CVD) Ti/TiN structure was found to be a more effective diffusion barrier in Cu metallization than TiN alone. The Ti and TiN films were deposited by plasma enhanced CVD and low pressure CVD, respectively. In order to reduce the concentration of chlorine in the films, ${\mathrm{NH}}_{\mathrm{3}}$ plasma posttreatment was applied to multilayered CVD-Ti/TiN films. The resistivity of the film was reduced from 240 to 120 $\mathrm{\mu \Omega }$ cm using ${\mathrm{NH}}_{\mathrm{3}}$ plasma posttreatment. Cu was electroplated on the multilayered CVD-Ti/TiN films. X-ray diffraction patterns showed a small (002) peak and strong (111) peak from the Cu film. The leakage current was kept low during the device application test indicating the Ti/TiN film possessed an enhanced barrier property over the TiN film alone.