Nucleation, growth and dissolution of extended defects in implanted Si: impact on dopant diffusion

Transient Enhanced Diffusion (TED) of boron in silicon is driven by the lar ge supersaturations of self-interstitial silicon atoms left after implantat ion which also often lead to the nucleation and subsequent growth, upon ann ealing, of extended defects. In this paper we review selected experimental results and concepts concerning boron diffusion and/or defect behavior whic h have recently emerged with the ion implantation community and briefly ind icate how they are, or will be, currently used to improve "predictive simul ations" softwares aimed at predicting TED. In a first part, we focuss our a ttention on TED and on the formation of defects in the case of "direct" imp lantation of boron in silicon. In a second part, we review our current know ledge of the defects and of the diffusion behavior of boron when annealing preamorphised Si. In a last part, we try to compare these two cases and to find out what are the reasons for some similarities and many differences in defect types and thermal evolution depending on whether boron is implanted in crystalline or amorphous silicon. While rising many more questions, we propose a "thermodynamical" vision of the nucleation and growth of clusters and extended defects and stress the interactions between these defects and the free Si self-interstitial atoms which surround them and are the source for TED in all cases. A pragmatic approach to the simulation of TED for va rious experimental conditions is proposed. (C) 1999 Elsevier Science B.V. A ll rights reserved.