Some fundamental problems in low-energy ion implantation

Selected aspects of ion implantation at low energy are reviewed. Some are common to any ion implantation experiment or process, whereas others are specific to plasma based ion implantation (PBII). First, the physics of ion–solid interactions are outlined in the perspective of when to expect characteristic low-energy effects. Next, two examples are given, where low-energy implantation effects indeed deviate significantly from extrapolations of the high energy data. These are ion channelling and ion blistering on differently oriented silicon crystals. Following this, an attempt is made at identifying aspects of low-energy implantation that are relevant for PBII, particularly the ion energy and impact angle distributions. Finally, suggestions for further work are proposed, especially in connection with the fabrication of nano-scale lithographically patterned devices.