Electromigration and Line R of Graphene Capped Cu Dual Damascene Interconnect
A selective graphene (Gr) CVD process for 300 mm wafers at BEOL compatible temperatures (<400 °C) for application as a cap on copper interconnects and a dielectric deposition on top of the Gr cap without impacting Gr quality by functionalizing the Gr surface to promote nucleation of the dielectric film. The integrated Gr and dielectric deposition processes enabled fabrication of integrated dual damascene Cu/low-k interconnects in the metal pitch of 30 nm. Observed poor electromigration (EM) reliability of Gr capped Cu interconnects with 16 nm metal width was in good agreement with our Ab Initio calculation of binding energy of Gr to Cu. Instead, Cu interconnects with Gr cap on selective Co cap showed decent EM reliability with reduction of line resistance up to 5 %, providing a promising solution for Cu extension.