Field effect transistor (FET) with a gate having a recessed work function metal layer and method of forming the FET

摘要

Disclosed is a field effect transistor (FET) with a replacement metal gate (RMG) and a method of forming the FET. The RMG includes a conformal gate dielectric layer and a stack of gate conductor layers on the gate dielectric layer. The stack includes a conformal work function metal (WFM) layer and a conductive fill material (CFM) layer on the WFM layer. Within the stack, the top surface of the CFM layer is above the level of the top of an adjacent vertical portion of the WFM layer. A dielectric gate cap has a center portion and an edge portion. The center portion is above the top surface of the CFM layer and the edge portion is above the top of the adjacent vertical portion of the WFM layer and is further positioned laterally immediately adjacent to an upper portion of an outer sidewall of the CFM layer.