MODELING RADIOFREQUENCY DISCHARGES - EFFECTS OF COLLISIONS UPON ION AND NEUTRAL PARTICLE ENERGY-DISTRIBUTIONS

Using a recently published description of the potentials in a radio-frequency discharge [Y. P. Song, D. Field, and D. F. Klemperer, J. Phys. D 23, 673 (1990)] Monte Carlo trajectories of ions and neutral particles for an Ar plasma have been computed, including collisions at the realistic pressures of tens of mTorr used for reactive ion etching. The model for collisions involves both charge exchange and momentum-transfer scattering. Ion and neutral energy and angular distributions have been calculated for particles impacting on the powered electrode and the calculations agree with an experimental ion energy distribution for Ar+. The presence of a large proportion of energetic neutrals is predicted, and it is suggested that these may have an important role to play in etch mechanisms.