Particle-based kinetic simulations of dual-frequency RF breakdown*

Dual-frequency, capacitively coupled plasmas (CCPs) have been utilized to control plasma density and ion velocity distribution functions. A one-dimensional (1D) particle-in-cell Monte Carlo collision (PIC-MCC) model is developed to investigate dual-frequency, radio frequency (RF) breakdown. First, the high-frequency (HF) breakdown voltages, V_HF, at f_HF=27.12 MHz are obtained when applying a constant low-frequency (LF) voltage, V_LF=283 V, at f_LF =2 MHz. The HF breakdown voltages obtained from the PIC-MCC simulation show good agreement with experimental data when the ion-induced electron emission and electron elastic reflection are considered. Next, we ran simulations to find that leads to breakdown when varying f_LF from 50 kHz to f_HF with V_LF=283 V and f_HF=27.12 MHz. As V_LF is well above the single-frequency RF Paschen curve, V_HF=0 V when f_LF=f_HF. However, when f_LF H_F, HF breakdown voltages are non-zero and depend on f_LF. The simulation results suggest that the phase lag of the ion induced electron emission relative to the voltage waveform plays an important role in determining the dual-frequency breakdown voltages.