Boron-enhanced-diffusion of boron: The limiting factor for ultra-shallow junctions

Reducing implant energy is an effective way to eliminate transient enhanced diffusion (TED) due to excess interstitials from the implant. It is shown that TED from a fixed Si dose implanted at energies from 0.5 to 20 keV into boron doping-superlattices decreases linearly with decreasing Si ion range, virtually disappearing at sub-keV energies. However, for sub-keV B implants diffusion remains enhanced and x/sub j/ is limited to /spl ges/100 nm at 1050/spl deg/C. We term this enhancement, which arises in the presence of B atomic concentrations at the surface of /spl ap/6%, Boron-Enhanced-Diffusion (BED).