Fluoropolymer Outgassing in Micro-and Nanofabrication

For improved micro- and nano-fabrication, we investigated the outgassing characteristics of fluoropolymers for the semiconductor industry on exposure to 157 nm, and for poly(tetrafluoroethylene) (PTFE) on exposure to a focused ion beam (FIB). The volatiles from these fluoropolymers were observed by in-situ quadrupole mass spectrometry. On exposure to 157 nm, side chain scission and the C-F bond play an important role in the outgassing process. Some fluoropolymers produce harmful HF which can damage exposure tools. HF evolution strongly depends on the polymer structure rather than the fluorine content, and can be reduced by optimizing the polymer structure. In contrast, main chain scission plays an important role in the outgassing characteristics of PTFE during FIB exposure. Fluorocarbons close to the upper detection limit of 298 amu were observed, and there is a possibility that some species with masses greater than 298 amu may evolve from the PTFE.