Nonlinear resonance effects on electron heating in capacitive discharges

Abstract

In capacitive radio frequency discharges operated at gas pressures below 20 mTorr two mechanisms of electron heating play a major role: i) ohmic heating due to collisions of electrons with neutrals of the background gas and ii) stochastic heating - often referred to as Fermi heating - due to momentum transfer from the oscillating boundary sheath. In this contribution we show that the plasma series resonance due to interaction of the plasma bulk and the nonlinear sheath significantly effects the electron heating. The series resonance can enhance both the ohmic and stochastic heating by factors of 2-5. We conclude that the nonlinear plasma dynamics has to be taken into account in order to describe quantitatively correct electron heating in low-pressure capacitive radio frequency discharges.