Mechanism of RF plasma induced fragmentation of SiCl4 and surface functionalization of polymeric substrates from SiClx species

Abstract

The generation of extremely reactive species of silylium (silicenium) ions under plasma conditions opens up new ways for surface modification, even of the most inert polymeric surfaces. To control the plasma-induced chemistry and to tailor new molecular surface architecture, the mechanism of formation of the active species of the discharge must be understood. In this work the plasma-induced molecular fragmentation of SiCl4 was studied and the surface functionalization of cellulose paper (CP), polyester (PET), polypropylene (PP), and polytetrafluoroethylene (PTFE) substrates with silicon atom based active species was evaluated. Gas chromatograph mass spectroscopy (GC-MS) and low Energy Electron MS (LEEMS) measurements carried out both on SiCl4 and on the molecular mixture resulting from the recombination of plasma generated species indicate that the most predominant fragments are SiCl3+ cations accompanied by SiCl2+ and SiCl+ species. Survey and high-resolution electron spectroscopy for chemical analysis (ESCA) data collected from plasma functionalized surfaces show significant silicon and oxygen atom content regardless of the nature of the substrates. © 1996 John Wiley & Sons, Inc.