Grid-shadow effect in grid-enhanced plasma source ion implantation

A grid-shadow effect is observed in grid-enhanced plasma source ion implantation (GEPSII), in which ions produced within the plasma region are extracted through a grid electrode and are then accelerated to the inner surface of a cylindrical bore for implantation. By simulating the ion transportation behaviors from the grid electrode to the inner surface using a Monte Carlo model, we find that the grid-shadow effect results from grid blocking of the ion emission on the grid electrode and that it varies with the experimental parameters such as the gap distance between the grid electrode and the inner surface, the gas pressure, and the applied negative potential.