A planar electrode is not directly connected to a high frequency generator, but separated by a capacitor. Therefore electrons charging the electrode in its positive phase cannot escape and are collected on this electrode. This causes negative DC charging of this electrode. A negatively charged electrode causes acceleration of positive charged ions onto this electrode. A substrate positioned onto this electrode will be bombarded by these high speed ions. The kinetic energy of these ions causes physical etching of the substrate. This effect is used for ion etching (IE) and Reactive ion etching (RIE).
Plasma systems using the Self-BIAS-effect usually work with high frequency in the MHz-range.