Enabling Cu-Cu connection in (dual) damascene interconnects by selective deposition of two different SAM molecules

Two different material-selective Self assembled monolayers (SAMs) were successfully deposited on Cu and SiO₂ structures that mimic the Dual Damascene integration scheme. A two-step SAM coating process is presented. First, a “sacrificial” SAM is deposited at the Cu bottom and secondly, a “barrier” SAM at the SiO₂ surface. The order in the SAMs deposition sequence and the differential thermal release of the thiol “sacrificial” SAM vs. the amino “barrier” SAM, allows an oxide-free Cu-to-Cu connection at the vias bottom. While the sacrificial SAM is selectively released by thermal ablation, the barrier SAM remains intact on the dielectric sidewall and field regions, ready for the subsequent copper metallization.