Development of 40 MHz inductively coupled plasma source and frequency effects on plasma parameters

Abstract

A large-area inductively coupled plasma (ICP) source capable of securing azimuthal plasma uniformity at a 40.00 MHz has been developed. The antenna, referred to as a capacitor distributed resonance antenna, minimizes the azimuthally nonuniform antenna capacitive field with eight distributed vertical capacitors. The antenna was designed to maximize the antenna current using L-C series resonance. Based on plasma diagnostics with a 13.56 MHz conventional ICP, comparative analyses were performed in terms of the plasma density, electron temperature, and frequency characteristics of the electron energy probability function (EEPF). In addition, the frequency dependency of the EEPF was found in the collisional (nu(en)>omega), normal skin [v(th)/delta <<(omega(2)+nu(2)(en))(1/2)] regime and the physical causes of were examined.