Dual-Work-Function Metal Gates by Full Silicidation of Poly-Si With Co-Ni Bi-Layers

摘要

Dual-work-function metal gates fabricated by full silicidation (FUSI) of Co-Ni bi-layer with doped poly-Si were investigated for the first time, along with single-metal FUSI systems of CoSi{sub}2 and NiSi. Complete conversion of poly-Si into Co-Ni alloy silicided metal gate (FUSI) Co{sub}xNi{sub}(1-x)Si{sub}2 was demonstrated. Although a linear relationship between work function and Ni percentage was observed for FUSI of undoped poly-Si systems, the work functions of doped Co{sub}xNi{sub}(1-x)Si{sub}2are almost identical to those of doped NiSi FUSI metal gates. The alloy FUSI metal gates explored in this letter provide a new class of metal gates for CMOS devices that combine the advantages of both NiSi and CoSi2, i.e., proper work function tunability of NiSi and high thermal stability of CoSi{sub}2.