Point defect engineering in preamorphized silicon enriched with fluorine

Fluorine is known to have a beneficial role for the B diffusion reduction in preamorphized Si, and is promising for the realization of ultra-shallow junctions. Thus, we studied the F incorporation in Si during the solid phase epitaxy (SPE) process, pointing out the effects of the implanted F energy and fluence and the, role played by the possible presence of dopants. The incorporation of fluorine proceeds by F segregation at the amorphous-crystalline interface, with a kinetics driven by the SPE rate. In fact, the quicker the SPE rate, the higher is the F fluence retained. Moreover, we demonstrated that F incorporated in Si layers does not appreciably affect the Is emission from spatially separated end-of-range (EOR) 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. We showed that F is not only able to completely suppress the boron transient enhanced diffusion (TED), but can enhance the antimony diffusion. These experimental data demonstrate the ability of F in inducing an Is undersaturation or a Vs supersaturation, ruling out the hypothesis of a chemical bonding between F and the dopants. These results improve the engineering of F-enriched Si, for the realization of ultra-shallow junctions. (c) 2006 Elsevier B.V. All rights reserved.