Binding Energy of Vacancies to Clusters Formed in Si by High-Energy Ion Implantation

Measurements of the binding energy (E sub b) of vacancies to vacancy clusters formed in silicon following high-energy ion implantation are reported. Vacancy clusters were created by 2-MeV, 2 x 10 sup 15 cm sup -2 dose Si implant and annealing. To prevent recombination of the excess vacancies (V sup ex) with interstitials from the implant damage near the projected range (R sub p), a Si-on-insulator (SOI) substrate was used such that the Rp damage was separated from the V sup ex by the buried oxide (BOX). Two V sup ex regions were observed: on in the middle of the top Si layer (V sub x sup ex) and the other at the front Si/BOX interface (V sub 2 sup ex). The rates of vacancy evaporation were directly measured by Au labeling following thermal treatments at temperatures between 800 and 900 degrees C for times ranging from 600 to 1800s. The rate of vacancy evaporation from V sub 2 sup ex was observed to be greater than from V sub 1 sup ex. The binding energy of vacancies to clusters in the middle of the silicon top layer was 3.2 +- 0.2 eV as determined from the kinetics of vacancy evaporation.