Radiofrequency power behaviour of low pressure triglyme plasmas

Abstract

Plasma polymerization of ethylene glycol monomers obtained from RF-excited low temperature plasma is promising technique for obtaining non-fouling hydrophilic biocompatible surfaces that may be used in many scientific and technological applications. The use of plasma diagnostics for optimizing the processes is an important issue to be addressed on plasma materials processing for customized biomedical applications. This paper deals with the RF power dependence of different chemical species in low pressure RF-excited CH3O(CH2CH2O)3CH3 tri-ethylene glycol di-methyl ether (triglyme) plasmas for different values of pressure. The RF-power was coupled to the plasma chamber though an appropriate matching network in order to optimize the process. The RF power was varied from 5 to 45 watts. The results showed that the population of different chemical species resulting from monomer fragmentation presents a strong dependence on RF power. It can be seen that the population of heavier species decrease with RF power followed by the increasing of the lighter one. This result is in close agreement with the increase of electron temperature at higher RF power levels. Therefore one can conclude that the monomers functionality is preserved within the plasma-deposited thin films if the RF power is kept in low levels during the process.