Features of Electromagnetic Field Excitation in a Capacitive HF Discharge. II. Symmetric Discharge Completely Filling Vacuum Chamber under Symmetric and Asymmetric Excitation

Abstract

Electrodynamic characteristics of a low pressure (electron collision frequency much lower than the field frequency) capacitive high frequency (HF) discharge maintained by electromagnetic field with a frequency between 10 and 1000 MHz are studied analytically and numerically. The discharge is assumed to fill completely a cylindrical metallic discharge chamber that contains a large area active electrode and a substrate holder connected to HF generators. The discharge is sustained by surface waves propagating along the plasma–space-charge sheath–metal interface. General analytical expressions governing impedance of the discharge are derived treating it as a two-point network. It is demonstrated that excitation of higher-order field modes substantially modifies position of current and voltage resonances related to propagation of surface waves along the three-layer structure as functions of electron density. Regimes of field excitation by symmetric and antisymmetric fields are analyzed within the framework of the matrix sheath model. Contribution of sheath formed near the sidewall of the vacuum chamber to the impedance must be taken into account in the case of excitation by an antisymmetric field. Obtained results qualitatively agree with numerical calculation of the impedance and field space distribution in the discharge carried out by using the COMSOL Multiphysics® software package.