FOUP Contamination and Limitation of Cleaning Procedure : Topic/category CFM, Contamination Free Manufacturing

The Front Opening Unified Pod (FOUP) is used to protect wafers from the Fab environment when they are not being processed. During Gate stack etch, a process known to be a potential source of etch residuals, wafers are separated in a different FOUP to avoid cross contamination. We show that the FOUP in which the wafers are placed can itself be a source of contamination. The contamination is found through inspection and it can also be shown to have a detrimental impact on product yield. We argue that outgassing of the FOUP is the source of the contamination and that an established cleaning process is insufficient to completely remove the contamination. The issue is eliminated by a change of type of FOUP used to contain the wafers.