Interactions of point defects and impurities with open volume defects in silicon

Ion implantation can produce open volume defects in silicon by one of two methods, either by H or He implantation followed by annealing to create a band of nanocavities and also by direct implantation to reasonably high doses, which results in a vacancy excess region at depths less than about half the projected ion range. This paper reviews three interesting aspects of open volume defects. In the first case, the very efficient gettering of fast diffusing metals to nanocavities formed by H-implantation is illustrated. In addition, the non-equilibrium behaviour of Cu₃Si precipitation and dissolution at cavities is examined. The second example treats the interaction of irradiation-induced defects with nanocavities, particularly preferential amorphisation at open volume defects and subsequent cavity shrinkage. The final example illustrates the coalescence of excess vacancies into small voids on annealing and the use of gettering of Au to detect such open volume defects.