Low-energy implantations of decaborane (B/sub 10/H/sub 14/) ion clusters in silicon wafers

Low-energy implantation with decaborane (B/sub 10/H/sub 14/) ion clusters is suitable for ultra-shallow junction formation. Using a high-voltage research implanter with a microwave ion source, decaborane implantation has been performed at energies in the range 2.8 to 440 keV, with doses up to 10/sup 14/ decaborane/cm/sup 2/ (10/sup 15/ B atoms/cm/sup 2/). A study of the implantation damage shows that the number of displaced Si lattice atoms in the near-surface region is considerably larger for the decaborane implants than for the corresponding B/sup +/ implants. Ultrashallow dopant profiles have been achieved by 2.8 keV B/sub 10/H/sub 14//sup +/ implantation, equivalent to an energy of 255 eV per incoming B atom. In such a case the B peak concentration is located only a few atomic layers below the Si surface, and implantation damage is virtually absent. Transient enhanced diffusion effects during rapid thermal annealing were negligible, apart from the slight movement associated with migration of interstitial B atoms onto substitutional sites.