Influence of target geometry on maximum electric field in plasma immersion ion implantation

Summary form only given, as follows. Plasma immersion ion implantation (PIII) is an effective surface modification technique. In PIII, a bias voltage is applied to the target to accelerate ions from the surrounding plasma into ate target. The electrical field thus depends very much on the applied voltage, plasma density, target shape, and other instrumental factors. There is a also a maximum electric field to avoid arcing. For pressure lower than 1 Pa, this field strength is on the order of 10kV/mm. In PIII processes, this limiting field strength occurs at the beginning of each voltage pulse because the field decrease as the plasma sheath expands. In the treatment of three-dimensional samples, the field is enhanced at edges or protrusions and the extent depends on the shape and relative dimensions. In this work, we simulate the electrical field around a rhombus-shaped target using the two-dimensional Poisson's equation. The target geometry is varied from 30 to 150 degrees to demonstrate the effects of the edge angle on the electrical field. We also discuss the influence of the target size, plasma density, and applied voltage on the electrical field.