High temperature ion beam erosion of polytetrafluoroethylene

In this work we have studied the ion beam etching rates of PTFE by changing N-ion fluence at different sample temperatures. PTFE substrates were irradiated with 160 keV N ions to a dose range between 1 x 10(14) and 4 x 10(16) ions/cm(2). The treated samples were examined by visible (514.5 nm) Raman spectroscopy as well as by scanning electron microscopy Mechanical properties of the implanted layers were assessed by scratch-testing in conjunction with profilometry. Radiation cross-linking and polymer degradation by chain scission are competing processes in this type of polymer depending on the irradiation temperature. Flexible-chain polymers are easier to cross-link than rigid-chain polymers like PTFE, however, the latter can be cross-linked if temperature is high enough. It is shown that ion irradiation at room temperature even in the low dose range leads only to chain scission while at temperatures higher than the glass transition, evidence for cross-linking and consequent stiffening are found. (C) 2003 Elsevier B.V. All rights reserved.