Method of forming low resistance vias

摘要

Low resistant vias are formed by sequentially treating an opening in an interlayer dielectric and the exposed surface of a lower metal feature with an NH3 plasma followed by a N2/H2 plasma, thereby removing any oxide on the metal surface and removing residual polymers or polymeric deposits generated during etching to form the opening. Embodiments include forming a dual damascene opening in a low-k interlayer dielectric exposing the upper surface of a lower Cu or Cu alloy feature, sequentially treating the opening and the upper surface of the lower metal feature with an NH3 plasma and then with a N2/H2 plasma, Ar sputter etching, depositing a barrier layer lining the opening, depositing a seedlayer and filling the opening with Cu or a Cu alloy.