Electron dynamics during the reignition of pulsed capacitively-coupled radio-frequency discharges

Abstract

The authors report on phase resolved optical emission spectroscopy (PROES) measurements of pulsed capacitive coupled plasmas (CCPs) through argon. The PROES results indicate that under some conditions, the electron heating mechanism can be changed substantially from that dominant in continuous CCPs. The normally dominant α heating mode of electropositive plasmas can be aided by a drift-ambipolar (DA) heating mode during the early portion of the reignition. The DA heating mode is ordinarily only found in electronegative discharges. The authors found that Ar discharges pulsed at 10 kHz only exhibited the α heating mode throughout the reignition process, while those pulsed at 0.1 kHz exhibited a mixed α and DA heating mode during the reignition. The differences in the two heating modes cause substantial differences in the spatial pattern of the light emission from the plasma in addition to an overshoot in the light emission intensity.