Fluorine effects on silicidation of BF₂⁺-implanted narrow poly lines

The use of BF₂⁺ for p⁺ source/drain implant has resulted in void formation in TiSi₂ films on p⁺ poly and diffusion regions due to the interaction between fluorine outdiffusion and Ti silicidation. When using B⁺ instead of BF₂⁺, no voids were observed. Deposition of a TEOS layer (150 Å) as a fluorine gettering source before p⁺ activation anneal reduces the number of voids formed considerably. The sheet resistance of the silicided p⁺ narrow poly has improved substantially with the reduction or elimination of the fluorine-induced effects