A diffusion pathway was proposed for a fluorine-silicon interstitial pair (F-Sii) in silicon, based on extensive first-principles density functional calculations. It was found that the F-Sii pair to be most stable in the singly positive charge state under intrinsic conditions and could exist in nearly degenerate bound and unbound states. It was determined that the unbound pair could undergo diffusion with a barrier of approximately 0.4 to 0.5eV by a coordinated motion until dissociating into F and Si interstitials at a cost of 1.3eV. The results suggested that Si interstitials, when they exist in excess, could play an important role in F redistribution and precipitation during thermal treatments.

Prediction of the Anomalous Fluorine-Silicon Interstitial Pair Diffusion in Crystalline Silicon. S.A.Harrison, T.F.Edgar, G.S.Hwang: Physical Review B, 2006, 74[12], 121201