| This dissertation is an experimental study of ion dynamics above the substrates of commercial semiconductor plasma processing devices. Experiments were performed on equipment donated by industrial partners, the Novellus and Intevac corporations. Laser-Induced Fluorescence measurements have been made with unprecedented spatial and temporal resolution. The dynamics of the transition layers above the substrate, known as the sheath and pre-sheath, have been investigated with and without the presence of a high-voltage, radio frequency (rf) bias applied to the substrate. The ratio of ion transit time tau ion to the rf period taurf was 0.3, in the so-called intermediate frequency regime.;While the ion energy distributions within the sheath were observed to vary dramatically over an rf cycle, the time-averaged distributions yielded the characteristic bimodal shape found to bombard rf substrates in previous experiments and theories. The position of the sheath width was found to be 3.6 mm above the biased substrate, independent of rf phase. The ion current and heat flux were found to be strongly modulated by the rf bias; the phase lag between the strongest sheath electric fields and the maximum observed current was between 0.25pi to 0.5pi, in accord with the predicted value of 0.3pi.;The findings reported in this dissertation may be helpful for developing and benchmarking computer models of rf sheath physics; the large data sets that have been obtained provide the opportunity for detailed spatial and temporal comparison of ion dynamics. Furthermore, since chemical reactions occur on time scales much smaller than the rf bias period, the strong temporal fluctuations of the ion energy could be of great interest to plasma chemists. |
