Ion energy distribution function in dual-frequency rf capacitively coupled discharges: analytical model.

An analytical approach is used to calculate an ion energy distribution function (IEDF) in a dual frequency (DF) collisionless rf discharge in argon. Three possible limit regimes for frequency relations in the DF discharge are discussed. The analytical IEDF is obtained for the intermediate-frequency case, which is most applicable in plasma-processing technologies. The analytical expressions for an ion spectrum width as well as for the minimum and maximum ion energies are derived. The analytical theory is compared with a particle-in-cell Monte Carlo numerical simulation and also with the results of a semianalytical model.