Electron heating in capacitively coupled discharges and reactive gases

Abstract

The effective collision frequency νeff of electrons in capacitively driven discharges of Ar∕Kr, Cl2 and BCl3 has been investigated using self-excited electron resonance spectroscopy. The most prominent features are the steep increase of νeff at low power inputs in all three gases and a slight but systematic decrease of νeff versus p for Ar∕Kr and BCl3 over the whole pressure range investigated. At medium pressures, the effective collision rate νeff in Cl2 increases by 2 orders of magnitude which is a clear manifestation for the transition from stochastic to ohmic heating. These features have been correlated with data gained with a V(I) probe. The dependence of the ohmic discharge resistance is mainly determined by the drastic change of νeff rather than by the variation of electron density ne.