Electron energy distribution function measurements and plasma parameters in inductively coupled argon plasma

Abstract

Electron energy distribution functions (EEDFs) have been measured in a cylindrical inductively coupled plasma (ICP) with a planar coil over a wide range of external parameters (argon pressure, discharge power and driving frequency). The measurements were performed under well-defined discharge conditions (discharge geometry, rf power absorbed by plasma, external electrical characteristics and electromagnetic field and rf current density profiles). Problems found in many probe measurements in ICPs were analysed and a rationale for designing probe diagnostics that addresses these problems is presented in this paper. A variety of plasma parameters, such as, plasma density, effective and screen electron temperatures, electron–atom transport collision frequency, effective rf frequency and rates of inelastic processes, have been found as appropriate integrals of the measured EEDFs. The dependence of these ICP parameters over a wide range of argon pressure, rf power and frequency results in experimental scaling laws that are suitable for comparison with ICP models and helpful in ICP design for many applications.