METHOD TO ATTAIN LOW DEFECTIVITY FULLY SILICIDED GATES

摘要

A method of forming fully silicided (FUSI) gates in MOS transistors which is compatible with wet etch processes used in source/drain silicide formation is disclosed. The gate silicide formation step produces a top layer of metal rich silicide which is resistant to removal in wet etch processes. A blocking layer over active areas prevents source/drain silicide formation during gate silicide formation. Wet etches during removal of the blocking layer and source/drain metal strip do not remove the metal rich gate silicide layer. Anneal of the gate silicide to produce a FUSI gate with a desired stoichiometry is delayed until after formation of the source/drain silicide. The disclosed method is compatible with nickel and nickel-platinum silicide processes.