Plasma characteristics observed through high-aspect-ratio holes in plasma

Ion species and their energy distributions impinging on a powdered electrode are investigated through high-aspect-ratio holes in the plasma of a magnetron etcher. A decrease in ion current and a change in ion energy distribution depending on the aspect ratio of holes were observed. The effects of inclined ion trajectory and charging at the side wall were examined theoretically and experimentally. It was found that the charging and a deposit on the side wall of holes greatly influenced the ions passing through holes.