Cobalt Interconnect On Same Copper Barrier Process Integration At The 7nm Node

Cobalt and copper interconnects with identical barrier and CMP processes were formed on ultra-low k (ULK) dielectric films at the 7nm node. Divot-free Co and Cu interconnects are demonstrated using the same CMP process. Co-filled dual damascene interconnects show high line yields with similar via resistance values compared to Cu. Co line resistance measures three times higher resistance than Cu. The resistivity of Co and Cu lines is calculated by measuring line resistance and cross-sectional area by transmission electron microscopy (TEM). Measured via resistance of the dual damascene Co-filled via is only 10% higher than the Cu-filled via control. Thus by scaling or even eliminating traditional Cu barriers in the via, Co can be a valid Cu replacement candidate for via fill.