Power dissipation and mode transition in an RF discharge with multi-hollow cathode electrode

Abstract

Multi-hollow cathode (MHC) discharge was investigated under various discharge conditions such as the discharge gas of Ar, Ne, and Kr, a pressure range from 64.5 mTorr to 645 mTorr, and a RF current range from 1 A to 9 A, in RF capacitively coupled plasma (CCP) with the cathode electrode having a number of holes of various hole diameters. The plasma parameters of electron density and electron temperature were measured with a compensated Langmuir probe and the electrical characteristics were obtained by using an RF impedance monitor (ENI-INC, V-I probe). It was found that the electron density significantly changes by controlling the discharge parameters, especially the gas pressure, with the cathode electrode of a fixed hole diameter. Furthermore, we could find that there is the optimum range of the discharge parameters that the electron density is maximized at a fixed hole diameter and the close relationship between the hole diameter and the discharge parameters. Comparing the MHC characteristics against the discharge gas to those of the conventional CCP, we could find that the variation behavior of the electron density against RF power for each discharge gas in the MHC was entirely different from that in the conventional CCP. These phenomena were explained by considering the power dissipation mode of electrons against the discharge conditions. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.