Efficacy of high-frequency, low-voltage plasma immersion ion implantation of a bar-shaped target

Elevated-temperature plasma immersion ion implantation (PIII) increases the surface hardness and thickness of the modified layer and is traditionally performed at a high energy (typically above 5 keV) and low current density. In this article, we report the benefits of a different approach by high-frequency, low-voltage plasma immersion ion implantation (HLPIII). Experiments and a two-dimensional theoretical simulation are conducted to demonstrate the advantages of the process on a bar-shaped sample in terms of ion dose, dose uniformity, and modified layer thickness. Simulation of the sheath dynamics illustrates that the thinner plasma sheath in HLPIII is geometrically more conformal to the target surface, and the incident ion flux is more uniform along the exposed surface when compared to the traditional high-voltage PIII process. The higher ion dose and thicker modified layer can be attributed to the higher ion current density. HLPIII is thus the preferred technique to enhance the surface properties of large and complex-shaped specimens such as a metal track.