Langmuir Probe Characterization of a RF Discharge Excited in Ar/C2F3Cl Mixtures during Plasma Deposition Processes

The apparatus for measurements of probe characteristic and its second derivative during plasma assisted thin film deposition is described. To avoid the probe surface contamination an impulse method combined with ion bombardment of the probe surface was used. Experimental evidence of the effectiveness of this method in the discharge fed with Ar/C₂F₃Cl mixtures is given. Measurements of the second derivative of the probe current have indicated an electron distribution different from the Maxwellian. Negative ions have been found in the discharge, the concentration of which has been estimated to be at most by one order of magnitude higher than the electron density.