Chemical-mechanical polishing of copper for interconnect formation

Abstract A systematic study of Cu chemical-mechanical polishing (CMP) in terms of process parameters influence, planarization ability of the process and pattern sensitivity of the polish rate was performed. We examined the effects of Cu dishing and SiO 2 thinning and the reasons for them. Both were found to be sensitive to the pattern geometry (line width and pattern factor) and the overpolishing time. The influence of the within-wafer nonuniformity in the polish removal on the polishing performance (planarity, line thickness) was also studied. Different optimization concepts in terms of the barrier/adhesion layer (Ta and WTi) were examined. CMP of Cu for damascene patterning was demonstrated and evaluated by electrical measurements as a promising technique for forming Cu lines.