Study of Power Balance in Electronegative Capacitively Coupled Plasmas

Abstract

The balance of power model is a relatively simple model, which determines the power dissipated both in the plasma bulk and in the plasma sheath, as well as the ion flux and the average energy lost by an electron in the plasma bulk. It requires only the measurement of the total power and the self bias voltage. The original model does not take into account the effect of the plasma potential on the energy of incoming ions, because for most plasmas, the plasma potential is negligible compared with the self bias voltage. In this work, the plasma potential was taken into account. For pure SF6 plasmas, the modification had a significant effect on the ion flux, which increased by more than a factor 2, when compared with the original model. Besides, there are strong indications that the silicon etching with SF6 was mostly determined by the plasma bulk power, but the contribution from ion bombardment was considerable, too. For less electronegative plasmas, the influence of the plasma potential may be neglected.