Spectroscopic Diagnostics of Glow Discharges: Frequency Effects.
29 September 1986
Frequency effects in radio frequency glow discharges are discussed in terms of simple equivalent circuits. Diagnostic data are presented which illustrate conversion from ionic to electronic power dissipation as the sheath becomes increasingly capacitive when frequency is increased from below to above the ion plasma frequency. The result is a shift in the position of radical formation from the sheaths to the plasma, an overall increase in the degree of dissociation, and a decrease in ion bombardment energies. The effects of negative ions on rf discharges are shown to be significant at low frequency but only for a small fraction of the rf cycle. At higher frequencies, the concentration of negative ions is not large enough to alter either the conducting properties of the discharge or qualitative predictions from the equivalent circuit model.