FOUP decontamination solutions to control AMCs in semiconductor fabs: Gas purge or wet cleaning?

This paper discusses two airborne molecular contaminants (AMCs) decontamination and control solutions for Front Opening Unified Pods (FOUPs), namely, inert gas purge and aqueous wet cleaning, and the effect these processes have on HF volatile acid cross contamination of Cu-coated wafers stored inside FOUPs of different polymer types, polycarbonate (PC), polycarbonate carbon powder (PCCP) and Entegris Barrier Materials (EBMCNT). The obtained results show that continuous FOUP purge appears to be an effective way to control HF cross contamination, to guarantee an optimum yield thanks to low humidity, and to clean chemically the environment from AMCs. Wet cleaning is an option after a high contaminating process. Wet cleaning removes the acid contamination from within the polymer near the surface, and removal efficiency is dependent on queue time; a higher removal rate is expected with a shorter queue time. The EBMCNT FOUP is the best of the materials tested in terms of HF contamination transfer reduction. Finally, numerical simulation (using a simple membrane model) shows that irreversible contamination results from the accumulation of the residual contamination in the polymer.