Effects of capacitance termination of the internal antenna in inductively coupled plasma

Abstract

In a conventional inductive rf discharge, the electrostatic coupling from the coil to the plasma causes a serous problem of sputtering of any dielectric materials in the vicinity of the coil. This paper reports the suppression of the electrostatic coupling by terminating the coil (inductance L ) with a capacitor (capacitance C ). The suppression resonantly takes place when the termination reactance (1/C ) coincides with a half of the coil reactance (L ). In this condition, the plasma density is observed to increase by ~50% at the same input power, in comparison with the conventional internal antenna inductively coupled plasma without the capacitance termination. The electrical transmission-line properties of the coil well account for the termination capacitance dependence of the coil voltages, currents, plasma potential oscillation, plasma density and dc self-bias voltage.