Transient enhanced diffusion of dopant in preamorphised Si: The role of EOR defects

Transient enhanced diffusion of boron is observed during annealing of preamorphised Si wafers. This anomalous diffusion is seen to originate from the interaction between EOR defects and dopant. Dopant trapping also occurs on the dislocation loops. Upon annealing, these defects grow in size and reduce their density through the emission and capture of Si interstitial atoms and this phenomenon can be described within the framework of the theory of Ostwald ripening. The boron diffusivity enhancement that is experimentally noticed takes its origin in the large supersaturation of Si interstitials in the defect-rich region and to the strong coupling between boron atoms and these Si interstitials. Both phenomena are transient and quantitative informations allowing this diffusion to be simulated can be extracted from TEM images of the time evolution of the dislocation loops upon annealing.