It was recalled that F was known to play a beneficial role in B diffusion reduction in pre-amorphized Si, and was promising for the preparation of ultra-shallow junctions. Thus, F incorporation into Si during solid phase epitaxy was studied in order to point out the effects of the implanted F energy and fluence and the role played by the possible presence of dopants. The incorporation of F proceeded via F segregation at the amorphous/crystalline interface, with the kinetics driven by the solid phase epitaxy rate. The quicker the solid phase epitaxy rate, the higher was the F fluence retained. It was demonstrated that the F incorporated into Si layers did not appreciably affect the Is emission from spatially-separated end-of-range defects. The modification, induced by the presence of F, of the point defect density (Is and Vs) was also studied by means of B and Sb spike layers, used as local markers for Is and Vs, respectively. It was shown that F was not only able to suppress completely the B transient enhanced diffusion, but could enhance Sb diffusion. These experimental data demonstrated the ability of F to induce an Is undersaturation or a Vs supersaturation; thus ruling out the hypothesis of a chemical bonding between F and the dopants. These results improved the engineering of F-enriched Si for preparing ultra-shallow junctions.

Point Defect Engineering in Pre-Amorphized Silicon Enriched with Fluorine. G.Impellizzeri, S.Mirabella, F.Priolo, E.Napolitani, A.Carnera: Nuclear Instruments and Methods in Physics Research B, 2006, 253[1-2], 94-9