Experimental test of models of high-plasma-density, radio-frequency sheaths

Measurements of the rf-bias current and voltage applied to the substrate el ectrode of a high-density plasma reactor, combined with de measurements of the ion current at the electrode and capacitive probe measurements of the p lasma potential, enabled a rigorous, quantitative test of models of the ele ctrical properties of the sheath adjacent to the electrode. The measurement s were performed for argon discharges at 1.33 Pa (10 mTorr), ion current de nsities of 1.3-13 mA/cm(2), rf-bias frequencies of 0.1-10 MHz, and rf-bias voltages from less than I to more than 100 V. From the measurements, the cu rrent, voltage, impedance, and power of the sheath adjacent to the electrod e were determined and were compared to model predictions. The properties of the opposing sheath, adjacent to grounded surfaces, were also determined. The behavior of the two sheaths ranged from nearly symmetric to very asymme tric. Changes in the symmetry are explained by models of the sheath impedan ce. [S1063-651X(99)03501-1].