Anode passivation mitigation in ultra thick metal plating

Abstract

In IC manufacturing, ultra thick metal (UTM) plating poses significant challenges for the hardware. The plating tool is subject to operating at high current density for extended periods of time to fill UTM features and provide enough overburden for CMP. The anode is vulnerable to passivation at high currents typically found in the final plating step. The passivation results in rising resistance ultimately leading to a tool fault. Various hardware settings are explored supported with equipment trace data. Ultimately it was found that increasing fresh bath feed to the anode mitigates the problem.