Evaluation of diffusion barrier layers in Cu interconnects

In this paper, we compare the experimental results on the suitability of oxygen or nitrogen containing SiC (SiCO or SiCN) with conventional SiN as a capping layer to prevent Cu diffusion into interlevel dielectric (ILD) layer in a typical Cu based interconnect structure. In addition to reducing the dielectric constant (k) value of the barrier, SiCN and SiCO show comparable performance in terms of preventing the Cu diffusion as well as offering good dielectric breakdown strength.