Chemours in the Semicon Manufacturing Industry
Fluid handling system components
The availability of Teflon™ PFA allowed the development of a wide variety of components that have evolved over 25 years and are widely used in critical fluid handling systems in Semicon manufacture.
Teflon™ PFA HP—Low contamination potential, higher yields
The semiconductor industry entered the 1980s with an unrelenting drive toward narrower line widths for increasingly sophisticated chip performance. Correspondingly, chip manufacturing components needed higher purity levels to protect chip yields.
Chemours responded to this need by organizing and leading an effort with component manufacturers to lower the contamination potential of components. Chemours scientists found that the groups at the ends of the PFA polymer chains gave off fluoride ions at levels unacceptable for manufacturing the new chips.
Fluoropolymer end groups
It is interesting that the end groups of fluoropolymers, present in such small amounts, have a disproportionately large effect. But, being chemically dissimilar from the polymer chain, they apparently become much more available for reaction than in other polymers.
By 1986, Chemours developed a polymer, Teflon™ PFA EG, with the end groups reacted with ammonia and thereby converted to a more stable form. However the amide-capped end groups were still reactive and degradable, adding contamination.
By 1989 Chemours determined the lowest contamination potential structure: Teflon™ PFA HP. The manufacture of Teflon™ PFA HP involves in addition to advanced contamination control, a process to treat the polymer with hot elemental fluorine gas. The fluorine converts any reactive sites, including the end groups, to the highly stable, fully fluorinated structure.
The essential features of Teflon™ PFA HP are the maximally stable carbon-fluorine bonds, and the strong stability of the protected carbon-oxygen bond that links the pendant groups to the polymer backbone. That the carbon-oxygen link survives the hot fluorine gas demonstrates the exceptional non-reactivity of the structure selected by Chemours in the development of PFA.