Probe diagnostics of supermagnetron plasma with applications of continuous and pulse-modulated rf electric fields

Parameters of supermagnetron plasma produced by rf (radio frequency) pulse, with 49.6 ms on and 0.4 ms off, were investigated by probe characteristics measured at 10–100 μs after the rf pulse in order to avoid disturbance in the measurement. The plasma parameters obtained by a continuous rf electric field and the phase differences of the rf electric field to both parallel electrodes were compared with those of rf pulse plasma. A double probe was mainly used in Ar as a standard gas, and a single probe was used in He gas for rf electric field free measurements using pulse-modulated rf plasma. He gas was used for extended time measurements because of a low probe contamination as a result of sputtering from two electrodes. A high electron density of an order of 1011 cm−3 was observed at low gas pressure (20 mTorr) for Ar plasma, and a low electron temperature of 1.1–1.2 eV was observed for He rf plasma. As for an rf phase difference dependence between two rf powers supplied to two parallel electrodes, maximum and minimum electron densities were observed at phase differences of 180° and 0°, respectively.