CVD-Mn/CVD-Ru-based barrier/liner solution for advanced BEOL Cu/Low-k interconnects

Aggressive downscaling of the barrier/liner thickness is the key to meet line and via resistance requirements from 15nm metal half pitch and below interconnects. For this purpose, porous low-k(2.4) dielectric/Mn-based barrier/Ru-liner/Cu system was extensively studied. Mn-silicate (MnSiO3) formation, intrinsic Cu diffusion barrier property and O2 barrier efficiency of the system were demonstrated. A stack of 1nm Mn-based barrier/1nm Ru liner was successfully integrated in tight pitch dual damascene (DD) Cu wires and its extendibility to at least 15nm feature size was confirmed both morphologically and electrically. Although, it was shown that Mn/Ru-based system is intrinsically reliable from electro-migration (EM) perspective, the absence of the flux divergence at the via bottom was also established, which needs to be addressed. Overall, this work shows that the Mn/Ru-based system is a serious barrier/liner solution for future technology nodes.