Enhanced diffusion of boron by oxygen precipitation in heavily boron-doped silicon

The enhanced diffusion of boron has been investigated by analyzing out-diffusion profiles in the vicinity of the interface between a lightly boron-doped silicon epitaxial layer and a heavily boron-doped silicon substrate with a resistivity of 8.2 m Omega cm and an oxide precipitate (O.P.) density of 10 8 -10 10 cm(-3). It is found that the boron diffusion during annealing at 850-1000 degrees C is enhanced with the increase of the oxide precipitate density. On the basis of a model for boron diffusion mediated by silicon self-interstitials, we reveal that the enhanced diffusion is attributed to selfinterstitials supersaturated as a result of the emission from oxide precipitates and the absorption by punched-out dislocations. In addition, the temperature dependence of the fraction of the self-interstitial emission obtained analyzing the diffusion enhancement well explains the morphology changes of oxide precipitates reported in literature. Published by AIP Publishing.