Effect of BF2+ implantation on void formation in Ti-salicided narrow polysilicon lines

We report the formation of voids in TiSi2 films formed on deep submicron BF 2+-implanted polysilicon (polySi) lines. The void formation was strongly de pendent on BF2+-implant dose, the p(+) annealing temperature, and the polyS i linewidth. Using plan-view scanning electron microscopy and cross-section al transmission electron microscopy, both surface and subsurface voids were observed. The voids were distributed predominantly along the center of the p(+) polySi lines and near the TiSi2/polySi interface, especially for line widths less than subquarter-micrometer. X-ray photoemission spectroscopic a nalysis detected a mixture of SiFx (1 less than or equal to x less than or equal to 4) and TiFx (x = 3, 4) like species near the TiSi2/polySi interfac e during an in situ annealing of Ti and Si, providing further evidence that the voids are fluorine-assisted species. (C) 2000 The Electrochemical Soci ety. S1099-0062(00)03-074-1. All rights reserved.