Electron Monte Carlo simulations of single- and dual-frequency RF breakdown

Electron Monte Carlo (E-MC) simulations are performed to investigate single- and dual-frequency radio frequency (RF) breakdown for nitrogen. The E-MC simulation accounts for electron-induced secondary electron emission (SEE) and ion-induced electron emission (IIEE). For single-frequency RF breakdown at 27.12 MHz, the breakdown voltages obtained from the E-MC model agree with experimental data when accounting for SEE, inelastic reflection, and elastic reflection. In addition, the effects of anisotropic scattering for electron-neutral collisions on RF breakdown are evaluated. For dual-frequency RF breakdown at 2 MHz and 27.12 MHz, the high-frequency (HF) breakdown voltages, VHF, are obtained when applying fixed low-frequency (LF) voltages, i.e., VLF=283 V and 509 V. The dual-frequency breakdown curve, i.e., VHF, obtained from the simulations is in good agreement with experimental data, showing that IIEE is important in a wide range of pressures, and electron elastic reflection plays an important role in the low pressure regime. The phase lag of electron incident flux to the electrodes with respect to the voltage waveform is analyzed to show the importance of electron emission mechanisms for single- and dual-frequency RF breakdown.