Until recently in the area of discharge processing the emphasis has been on developing improved or new processes with less attention to the characteristics of the plasma itself. The need to better characterize the processing plasma and to acquire a predictive capability through modeling based on measurements reproducible at different laboratories has now been recognized. A standardized discharge configuration and electrical measurement methods were developed. Using these methods, we measured discharge characteristics in argon, helium and nitrogen. With a microwave interferometer, the line inte— grated electron densities were measured. Information on plasma loss mechanisms and ion species can be deduced from these measurements. Operated in pulsed mode, the decay time of the DC bias is important if negative ions and dust precursors are to be eliminated. To obtain reduced DC bias, increased plasma density and lower pressure operation, a magnetic field parallel to the electrodes was applied. The effect of the B—field depended on the attachment coefficient of the gas which determines the width of the electrode sheaths. To separate the plasma generation from the substrate treatment area and to operate at lower pressure and with controlled ion energy, an inductive discharge with an electron energy analyzer was used. At the lower pressure, the percentage of high energy electrons increased considerably. investigating discharges with helical resonators, we measured electron densities comparable to or exceeding those in parallel plate discharges.
