Factors influencing the formation and growth of faulted loops in BF+2 -implanted silicon

Abstract

Transmission electron microscopy has been applied to study faulted loops in BF⁺₂ ‐implanted silicon. (001)‐ and (111)‐oriented silicon were irradiated by BF⁺₂ ions to doses of 1×10¹⁴–1×10¹⁵ cm⁻² followed by annealing at 1000‐1200 °C in dry N₂, dry O₂, and wet O₂ for different periods of time (1 min. to 2 h). The oxygen content in the annealing ambient was found to be of critical importance in the nucleation and growth of faulted loops. The presence of oxygen atoms lowered the activation energy for the nucleation of faulted loops and increased the heterogeneous nucleation sites as well as accelerated the growth of loops. For the same foil, the difference in the growth rate of loops was explained in terms of the competition of the inflow of interstitial flux from the oxide/silicon interface and vacancy flux from the rest of silicon towards the interface. There was indication that the difference may arise because the defects were of different natures. Stress effect was invoked to discuss why faulted loops were more prominent in (001)‐oriented, lower‐dose samples than in (111)‐oriented, higher‐dose samples, respectively.