A method to reduce the diffusion of B in ultra-shallow junctions was found using the co-implantation of F and C. In this 24 designed experiment, a 40% reduction in B diffusion in the presence of a shallow F and C implant was found over the use of F alone. In addition another 10% reduction of B diffusion could be obtained if a medium-dose As implant was preformed before F and B implantation. It was found that implanting in this order significantly alters the defect structure of the ultra-shallow junctions and suggested that F trapped in the lattice after annealing may be tied up in vacancy F clusters which increased B activation.

Reducing Ultra-Shallow Boron Diffusion using Carbon and Fluorine Coimplantation. A.Vanderpool, M.Taylor: Nuclear Instruments and Methods in Physics Research B, 2005, 237[1-2], 142-7