CHEMICAL-MECHANICAL POLISHING OF COPPER FOR INTERCONNECT FORMATION

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 SiO2 thinning and the reasons for them. Both were found to be sensitive to the pattern geometry (line width an d pattern factor) and the overpolishing time. The influence of the wit hin-wafer nonuniformity in the polish removal on the polishing perform ance (planarity, line thickness) was also studied. Different optimizat ion concepts in terms of the barrier/adhesion layer (Ta and W-Ti) were examined. CMP of Cu for damascene patterning was demonstrated and eva luated by electrical measurements as a promising technique for forming Cu lines.