The use of time averaged emitting probes to study plasma processing

Sheaths in capacitive RF discharges play an important role in a variety of plasma processing techniques. Recently it has been demonstrated that time averaged emitting probe characteristics can be used to determine the maximum and minimum potential value of the time varying RF potential with good spatial resolution. This allows one to determine many of the details of time varying sheath potentials. A first step in the application of this technique to plasma processing by ions energized in sheath is presented. Sheaths in a dc multi-dipole plasma with RF coupled either with a capacitor or directly to conductors on which insulators are mounted are presented. Experimental data cover a range of frequencies and neutral pressures. An important issue considered is the value of the RF self bias of the insulator and of the plasma. In addition, evidence is presented for the presence of non-monotonic potentials