Identification of electromigration dominant diffusion path for Cu damascene interconnects and effect of plasma treatment and barrier dielectrics on electromigration performance

Electromigration testing pattern to identify the dominant diffusion path of Copper (Cu) damascene interconnects is proposed. It is confirmed that dominant diffusion path is the interface between Cu and barrier dielectrics using the proposed testing pattern. After identification of the dominant path, the effects of the plasma treatment and barrier dielectric SiC_xN_y and SiC_x on the EM performance is investigated. Failure analysis reveals that Cu oxide at the interface of SiC_x samples with H₂ plasma treatment accelerates the Cu EM diffusion, resulting in lower activation energy and shorter lifetime. In addition, it is also found that nitrogen at the interface retards Cu diffusion drastically.