Line-Width Dependence of Void Formation in Ti-Salicided BF2-Doped Polysilicon Lines

Abstract

AbstractWe report the first observation of voids in sub-quarter micron Ti-salicided BF2-dopedpolycrystalline silicon (polySi) lines. Some of the voids, with sizes ranging from 10 to 100nm, can be clearly seen on the surface of the TiSi2 film whereas others are situated below the TiSi2 surface. The void density and size increase with decreasing polySi line-width, especially for line-widths < 0.24 µm. The voiding phenomenon was also observed to be moresevere for TiSi2 fabricated with enhanced salicidation techniques such as pre-amorphization-implant(PAl) and implant-through-metal (ITM) as compared to the conventional salicidationmethod without amorphization. The origin of the voids is found to coincide with the fluorinepeak at the TiSi2/polySi interface in the SIMS depth-concentration profiles.