Ion Implantation Damage in Semiconductors

Abstract

The diffuse X-ray scattering from defects in ion implanted Si was studied at implantation temperatures ranging from 100 K to 300 K, and the results were compared to simulations of the scattering intensity from realistic defects in Si. In situ studies of keV implants identified close Frenkel pair defects as the primary defects caused by 4.5 keV He$\sp+$ and 20 keV Ga$\sp+$ implantations. The defects created by the He implant had separation distances of about 1.0 nm, and the defects were arranged mostly as single pairs and very small ($<$4) clusters of pairs. The defects created by the Ga implant were slightly more extended (2.0-2.5 nm) and consisted of slightly larger clusters (1-20) of Frenkel pairs. Asymmetry in the scattering intensity indicated the clustering of interstitials at high doses for both ion implants at temperatures as low as 100 K, and annealing of the scattering intensity at 170 K was also attributed to interstitial mobility. Clustering of interstitials preceded amorphization at high doses, indicating the possibility that such interstitial clusters provide a nucleation site for the amorphous material. No evidence for single impact amorphization was observed, and no effect of the surface was observed in measurements performed near the critical angle for total external reflection and also in the simulations.