Evolution of CoSi_2 buried structures created by high temperature Co~+ ion implantation into Si(100) during post-implantation annealing

摘要

The evolution of buried structures of cobalt disilicide, which are formed in a Si(100) matrix by 400 keV Co~+ ion implantation at 875 K substrate temperature with subsequent rapid thermal annealing at 1275 K was studied by cross-sectional transmission electron microscopy (X-TEM). The analysis of identical samples with successive variations of the implanted doses and annealing times allows a detailed observation of the role of defects, created by the ion flux, on the process of ripening and growth of CoSi_2 precipitates. We found that transport of the implanted material along diffusive links leads to the formation of a secondary CoSi_2 distribution between the main layer and the surface. Post-implantation annealing results in the evolution of defects into dislocations, which affects the mobility and therefore the growth of CoSi_2 precipitates. Increasing the annealing time leads to the separate growth of precipitates in each layer. The result is not the formation of a single uniform buried layer because the distance between the individual layers is too large due to a screening effect, which operates during the ripening stage.