Analysis of a Capacitively Coupled Dual-Frequency CF₄Discharge

We present particle-in-cell simulations of capacitively-coupled CF 4 RF discharges. For establishing the discharge plasma high frequency sources of either 13.56 or 100 MHz are used, while a low frequency 0.7–1.0 MHz source is applied for biasing. The simulation results demonstrate that an efficient decoupling between the plasma and the biasing sources can be achieved by optimizing the choice of frequencies. The decoupling is observed by a small effect of varying of the biasing voltages of the RF sources on properties of the bulk of the plasma and the flux of the CF 3 + ions hitting the electrodes, while the mean energy of ions increases with the biasing voltage. The 100 MHz/1 MHz case allows setting of these ion properties in an especially wide range. For high values of the low-(biasing) frequency RF voltage a small flux of energetic negative ions is also observed at the electrodes.