Fully Silicided Metal Gates for High-Performance CMOS Technology: A Review

Full silicidation (FUSI) of polysilicon gates promises to be a simple approach for formation of metal gate electrodes for highly scaled complementary metal oxide semiconductor (CMOS) transistors. Devices have been reported with several different silicides, prominently with nickel. NiSi was shown to produce different work functions, covering a large portion of silicon bandgap, in relation to a dopant type and amount present in polysilicon. Elimination of polysilicon gate electrode depletion has been demonstrated. Data indicates that significant reduction of gate tunneling current is possible. A summary of developments of this new approach to metal gates and discussion of issues and challenges of the FUSI process and its applicability to highly scaled technologies is presented.

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