Abstract: Plasma ion implantation, an alternative to conventional beam-line ion implantation, is a sheath-acceleration ion bombardment technique and the initial sheath is crucial to the process efficacy and surface properties. The initial spatial potential distribution in the plasma sheath around a trench-shaped target is simulated using a two-dimensional model in this work. The results demonstrate that the sheath structure depends very much on the trench width. The potential drop in the trench may be quite small and the sheath expands outward if the width is small. This leads to a smaller incident ion dose into the sidewalls of the trench. In contrast, the initial potential distribution in the central region is quite similar to that without a trench if the trench width is larger than twice the ion-matrix sheath thickness for an infinite plane. Consequently, a higher ion dose into the sidewalls is possible.

Key words: Plasma ion implantation, Trench target, Potential distribution