In fluence of helium admixture on charged particle dynamics in an electronegative oxygen capacitively coupled plasma

摘要

The in fluence of helium admixture on an electronegative oxygen capacitively coupled plasma is investigated by means of a one-dimensional numerical fluid model with semi-kinetic treatment of electrons. This model is operated at 100 Pa with a sinusoidal driving voltage at a frequency of 13.56 MHz and is solved self-consistently for each individual RF-cycle. The change in the spatial profiles of dominant charged particles (O_2~+, O~-, e) as well as the electronegativity are analysed under variation of the helium admixture. Discharge excitation dynamics, in particular of the atomic oxygen line λ = 844 nm (~3P -~3S) are investigated and compared to those observed from pure oxygen capacitively coupled plasma experiments. The simulations show that additional helium in the oxygen discharge acts as inhibitor for excitation mechanisms during the phase of sheath collapse.