Simulation of capacitively coupled single- and dual-frequency RF discharges

For a single-frequency capacitively coupled radio-frequency discharge, the detailed examination has been carried out of plasma density and sheath width, average potential profiles, ion-energy distribution at the electrodes and electron-energy distribution in the bulk plasma as a function of pressure, voltage, and frequency using particle-in-cell/Monte Carlo simulation. The results for Ar gas are presented. Scaling of plasma parameters with external parameters is determined. The characteristics of dual-frequency argon discharge are studied for different ratio of high/low frequencies. Nonmonotonous behavior of plasma density versus low-frequency voltages is attributed to the increase of sheath width and, as a consequence, to the increase of energy absorbed by ions in the sheath region. Subsequent decrease of energy absorbed by electrons results in the decrease of plasma density. For certain frequency ratio with the further increase of power, the plasma density increases again until the collapse of the bulk occurs.