Interstitial defects in silicon from 1-5 keV Si+ ion implantation

Extended defects from 5-, 2-, and 1-keV Si+ ion implantation are investigated by transmission electron microscopy using implantation doses of 1 and 3 x 10(14) cm(-2) and annealing temperatures from 750 to 900 degrees C. Despite the proximity of the surface, {311}-type defects are observed even for 1 keV., Samples with a peak concentration of excess interstitials exceeding similar to 1% of the atomic density also contain some {311} defects which are corrugated across their width. These so-called zig-zag {311} defects are more stable than the ordinary {311} defects, having a dissolution rate at 750 degrees C which is ten times smaller. Due to their enhanced stability, the zig-zag {311} defects grow to lengths that are many times longer than their distance from the surface. It is proposed that zig-zag {311} defects form during the early stages of annealing by coalescence the high volume density of {311} defects confined within a very narrow implanted layer. These findings indicate that defect formation and dissolution will continue to control the interstitial supersaturation from ion implantation down to very low energies, (C) 1997 American Institute of Physics.