Influence of grid and target radius and ion–neutral collisions on grid-enhanced plasma source ion-implantation process

Grid-enhanced plasma source ion implantation (GEPSII) is a newly proposed technique for inner surface modification of materials with cylindrical geometry. In this paper, a collisional fluid model is used to investigate the ion sheath dynamics between the grid electrode and the inner surface of a cylindrical bore during the GEPSII process. Assuming the initial ion density along the radial direction is not uniform but determined by diffusion mechanisms, the effects of grid electrode radius, target radius and ion-neutral collisions on the ion dose and impact energy are investigated by solving fluid equations for ions coupled with the Boltzmann assumption for electrons and Poisson's equation. The results show that a small gap distance between grid electrode and target is favorable for increasing the ion dose and impact energy on the target. In addition, ion-neutral collisions can reduce both the ion dose and impact energy.