Alternating fluxes of positive and negative ions from an ion–ion plasma

Relatively electron-free positive- and negative-ion plasmas (ion–ion plasmas) have been achieved in the afterglow of pulsed-power Cl2 discharges. The application of a low-frequency (20 kHz) bias voltage phase locked to the source power modulation and synchronous with the ion–ion plasma, resulted in alternating fluxes of positive (Cl2+) and negative (Cl−) ions on a substrate. These results qualitatively agree with a one-dimensional fluid model. This technique to produce alternate irradiations could be used to reduce differential charging-induced damage in high-aspect-ratio etching processes.