PLASMA ETCH TOOL FOR HIGH ASPECT RATIO ETCHING

High aspect ratio features are etched using a plasma etching apparatus that can alternate between accelerating negative ions of reactive species at a low energy and accelerating positive ions of inert gas species at a high energy. The plasma etching apparatus can be divided into at least two regions that separate a plasma-generating space from an ionization space. Negative ions of the reactive species can be generated by electron attachment ionization in the ionization space when a plasma is ignited in the plasma-generating space. Positive ions of the inert gas species can be generated by Penning ionization in the ionization space when the plasma is quenched in the plasma-generating space.