Diffusion models of BF2+ and B+ implanted at low-energy in crystalline silicon

We have investigated and modelled the diffusion of boron implanted into crystalline silicon in the form of boron difluoride BF2+. Low-energy BF2+ (2 keV) and dose of 1 × 1015 cm−2 have been used. Diffusion profiles have been measured using secondary ion mass spectrometry (SIMS). RTA were carried out at 950, 1000, 1050 and 1100 °C. The results show that concentration profiles for BF2+ implant are slighty shallower than those for a direct B+ ion implantation. This could be attributed to the presence of fluorine, which can trap interstitial silicon so that Si supersaturation is low near the surface. Following Uematsuʹs works, the simulations satisfactory reproduce the SIMS experimental profiles.