As device dimensions shrink, traditional UPW purity specifications no longer fully capture the contamination risks that affect yield. This presentation reviews the qualification of PEEK piping for advanced nodes, starting with standard SEMI leachout and particle tests and extending to TOC and fluoride rinse-up, particle precursors, and on-wafer "stickiness" of contaminants. Compared with PVDF, the results show PEEK offers shorter rinse times in hot UPW, lower TOC and fluoride levels, and lower combined yield risk on bare silicon wafers.