Patent ID: 8273645
Filing Date: 2012-09-25
Classification: H01L

Abstract:
1. A method of forming a fully silicided (FUSI) gate, comprising the steps of: forming a protective layer on a top surface of a polysilicon gate and a top surface of areas adjacent to said gate; selectively removing said protective layer over said gate whereby said protective layer is not removed from said adjacent areas; forming a layer of gate metal on a top surface of said gate; heating said gate metal and said gate so as to form a gate silicide layer in a top region of said gate with an atomic ratio of metal atoms to silicon atoms which is more than 50 percent higher than a desired FUSI stoichiometry of said FUSI gate; after heating said gate metal and gate, removing said protective layer from said adjacent areas whereby said gate silicide layer in said top region of said gate is not substantially removed; forming a layer of source/drain metal on said adjacent areas; heating said source/drain metal and said adjacent areas so as to form source/drain silicide layers in top regions of said adjacent areas subsequent to heating the gate metal and gate; then, removing unreacted source/drain metal by a process further comprising wet etching, whereby said gate silicide layer in said top region of said gate is not substantially removed; and after removing the unreacted source/drain metal, annealing said gate and said gate silicide layer in said top region of said gate to form a FUSI gate which has said desired FUSI stoichiometry.