Dual radio frequency sources in a magnetized capacitively coupled plasma discharge

Nonlinear interaction of two radio frequency (RF) sources in a magnetized Ar/C₂F₆ capacitively coupled plasma discharge is investigated using a computational model. Results show that application of a radial magnetic field enhances charged and neutral species densities in the plasma reactor due to reduction in electron loss to surfaces and trapping of secondary electron emission generated electrons. Amplitude of RF currents at electrodes also increases with magnetic field strength and source frequency for a given RF voltage. Due to nonlinear nature of plasma sheath, higher harmonics of applied frequencies and source interaction generated harmonics can be observed in electrode currents. Application of magnetic field decreases electron mobility and makes the system less nonlinear, which reduces higher harmonics relative to primary components. Magnetic field also tends to make the RF sources more isolated. Increase in source frequency moves the plasma from electrode edge to the center of the chamber, which redistributes current through the electrodes. If frequencies of the two RF sources are commensurate, nonlinear interaction of RF sources generates subharmonics of primary frequencies.