Reliability Investigation of Cobalt and Copper Damascene Interconnects with Capped Graphene

In this study, Damascene interconnects were fabricated on a 12-inch wafer, and a flatness process of cobalt and copper was achieved through chemical mechanical polishing (CMP). Subsequently, graphene was selectively deposited on the metal using a multisource electron cyclotron resonance chemical vapor deposition (MECR CVD) system at 400°C, while diamond-like carbon (DLC) was deposited on the oxide. The effect of graphene on the electromigration (EM) lifetime of the metal interconnects was studied. The results demonstrate that graphene can enhance the EM lifetime of metal interconnects and has a longer EM lifetime than uncovered metal interconnects. The average time to failure (MTTF) of copper and cobalt interconnects with a graphene cap increased by 54% and 116%, respectively. Additionally, simulation results showed that covering the interconnects with graphene can improve the heat dissipation of the damascene interconnect structure, lower the wire temperature, and further increase the maximum current density of the metal interconnects.