Experimental studies on the properties of the discharge modes in a cylindrical radio frequency inductively coupled plasma

Abstract

In this paper, Z-scan, current and voltage probe were used to measure rf discharge power, coupling coil rf current, voltage and dc plasma floating voltage in RF inductive dischargr, and the effects of impedance matching network, coil coupling intensity and the source ground area on the properties of E,H mode and the mode transition are investigated. The positive and negative feedback regions are put forth on the basis of the influence of the series capacitance in a Γ-type impedance matching network on RF output power of the RF power source. It is experimentally founded that under identical experimental parameters, the discharge mode evolution is apt to be discontinuous and continuous in the positive and negative feedback regions, respectively. In addition, the threshold coil RF current (or plasma absorbed power) corresponding to the mode transition, the hysteresis loop width, the difference in plasma absorbed power during the discharge mode transition vary evidently with the series capacitance of the impedance matching network. The threshold coil RF current of E-H mode transition is not necessarily higher than that of H-E mode transition. In combination with the influences of impedance matching network and discharge pressure, the modes of transition are diversified for different ground areas.