Pair diffusion and kick-out: Contributions to diffusion of boron in silicon



Diffusion of boron in silicon has great technological relevance to microelectronic processing. Despite considerable effort spanning over many years, the dominant mechanism for this diffusion remains strongly debated, together with the values of key activation energies. Some evidence indicates that the principal mobile species is a B-Si complex (so-called “pair diffusion”), whereas other evidence points to a lone boron interstitial (“kick-out”). An attempt to resolve the question is made by formulating a comprehensive kinetic model that incorporates both mechanisms. Rate parameters for the elementary steps are estimated systematically, based on literature reports or physical arguments. In the frequent cases where reports conflict, maximum likelihood estimation is employed to determine the best value, and multivariate statistics to quantify its accuracy. A Monte Carlo technique is used to show that kick-out very likely dominates pair diffusion in both implanted Si and unimplanted silicon. © 2004 American Institute of Chemical Engineers AIChE J, 50: 3248–3256, 2004