Phase and energy distribution of ions incident on electrodes in radio-frequency discharges

Abstract

A Monte Carlo particle simulation and parametric models for the sheath voltage and thickness were used to calculate the arrival phase and energy of ions striking the electrodes in low-pressure capacitively coupled rf discharges. Ion phase and energy distributions are presented as a function of rf frequency, ion mass, rf voltage, dc bias, sheath thickness, and gas pressure. When the rf frequency is below the ion response frequency, the ions arrive at the electrode in phase with the applied rf voltage. As the rf frequency increases, the highest ion arrival probability shifts towards higher phase until, at sufficiently high frequencies, it is nearly uniform. The transition from a highly peaked ion phase distribution at low frequencies to a uniform distribution at high frequencies requires at least an order of magnitude change in rf frequency. The implication of these calculations on the electron energy distribution is discussed.