Perfluorooctane sulfonyl fluoride as an initiator in hot-filament chemicalvapor deposition of fluorocarbon thin films

We have demonstrated the successful use of an initiator species in hot-fila ment chemical vapor deposition (HFCVD) of poly(tetrafluoroethylene) thin fi lms from the precursor hexafluoropropylene oxide (HIPPO). The introduction of perfluorooctane sulfonyl fluoride (PFOSF) in small concentrations allows the enhancement of deposition rates and increased control over film compos ition. Endcapping by CF3 groups is possible, which may provide benefits suc h as enhanced thermal stability and higher hydrophobicity for HFCVD films. Conversion of the PFOSF is high, and HIPPO utilization efficiency can be in creased significantly. The generation of an initiator radical via the pyrol ysis of PFOSF may contribute to enhanced nucleation rates during film growt h. Initiation and/or nucleation is rate-limiting at low filament temperatur es, and mass transport limitations dominate at higher filament temperatures .