In the Damascene approach for state-of-the-art ultra-large-scale integrated (ULSI) devices, copper is deposited by electrochemical deposition (ECD) into patterned dielectrics P1.However, ECD requires a continuous metallic nucleation layer over the diffusion barrier to initiate uniform plating and provide a conductive path P1.Following the deposition of the Ta-based liner in the MET6 module, this step establishes the requisite conductive Cu foundation P1.Unlike lower-level metals, MET6 in a 40nm