Formation of nanoscale voids and related metallic impurity gettering in high-energy ion-implanted and annealed epitaxial silicon

We have examined nanovoid formation, Fe gettering, and Fe clustering phenomena occurring in epitaxial silicon layers implanted with MeV Si ions. Insights into these phenomena as a function of depth have been gained from detailed analyses by Z-contrast imaging in conjunction with electron energy-loss spectroscopy. Our work has shown at the nanoscale structural and chemical levels that the defects produced by MeV self-ion implantation between the surface and the ion projected range Rp (i.e., in the so-called Rp/2 region) are voids, which provide extremely efficient and aggressive metallic impurity gettering. It has been proposed that the gettering does not occur via chemisorption or silicidation layering on the internal surface of the void walls, as in the well-known case of helium-induced cavities, but rather proceeds in a mode of metal-metal atom binding in the vicinity of the Rp/2 voids