| Abstract
| - Hexafluoropropylene oxide (HFPO) flow rate and filament preconditioning time were foundto strongly influence the structure and morphology of fluorocarbon films grown by hotfilament chemical vapor deposition (HFCVD). The four films discussed in this work allexhibited the vibrational frequencies of linear CF2 chains, which are also characteristic ofbulk poly(tetrafluoroethylene) (PTFE), as shown through Fourier transform infraredspectroscopy (FTIR). The films also incorporated hydroxyl (OH) and carbonyl/carboxyl (CO/COO) groups to varying degrees. Analogous to the behavior of irradiated PTFE, the OHand CO/COO groups may have formed when unterminated chain end radicals reacted withoxygen and water. The surface morphology of the four films, as revealed through atomicforce microscopy (AFM), ranged from spherical nodules to anisotropic rodlike grains. Anincreased aspect ratio of the grains and lower OH incorporation both correlated with thedecreased film deposition rate. The hypothesis that long CF2 chains with a preferred directionof growth are favored by slow deposition would account for both the anisotropy in morphologyand the reduction in OH chain ends. An analysis of the chamber effluent supports theproposed mechanism for thermal decomposition of HFPO during HFCVD.
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