Line-width dependence of void formation in TI-salicided BF 2-doped polysilicon lines

Abstract

We report the first observation of voids in sub-quarter micron Ti-salicided BF 2-doped polycrystalline silicon (polySi) lines. Some of the voids, with sizes ranging from 10 to 100 nm, can be clearly seen on the surface of the TiSi 2 film whereas others are situated below the TiSi 2 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 more severe for TiSi 2 fabricated with enhanced salicidation techniques such as pre-amorphizationimplant (PAI) and implant-through-metal (ITM) as compared to the conventional salicidation method without amorphization. The origin of the voids is found to coincide with the fluorine peak at the TiSi 2/polySi interface in the SIMS depth-concentration profiles. © 1999 Materials Research Society.