Electroplating Process Improvement on Post-CMP Dishing Profile

Copper damascene metallization has been widely utilized in integrated circuit fabrication to form metal interconnect structures through electrochemical plating (ECP) technology. When some large pads are patterned on incoming wafers, excessive dishing profiles are often observed after ECP and chemical mechanical polishing (CMP) process. Solutions to overcome overpolishing issues involve optimization of both CMP and ECP processes. For ECP process, leveler additives in plating solution are the major contributor to leveling the big pad. By adjusting the rotation speed of the wafer during plating steps, the mass transfer of large organic molecules near the wafer surface can be varied. In this work, it is observed that the total dishing defect count under optical microscope observation can be significantly reduced by decreasing the rotation speed during plating. It is expected that this study will be beneficial to copper electrochemical deposition for wafers with large Cu pads.