Effect of BF_2~+ Implantation on Void Formation in Ti-Salicided Narrow Polysilicon Lines

摘要

We report the formation of voids in TiSi_2 films formed on deep submicron BF_2~+-implanted polysilicon (polySi) lines. The void formation was strongly dependent on BF_2~+-implant does, the p~+ annealing temperature, and the polySi linewidth. Using plan-view scanning electron microscopy and cross-sectional 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 TiSi_2/polySi interface, especially for linewidths less than subquarter-micrometer. X-ray photoemission spectroscopic analysis detected a mixture of SiF_x (1 ≤ x ≤ 4) and TiF-x (x = 3, 4) like species near the TiSi_2/polySi interface during an in situ annealing of Ti and Si, providing further evidence that the voids are fluorine-assisted species.