Semiconductor device incorporating a multi-function layer into the gate stacks

Abstract

Approaches are provided for forming a semiconductor device (e.g., a FET) having a multi-function layer (e.g., niobium carbide (NbC)) that serves as a work function layer and a gate metal layer in gate stacks of solid state applications. By introducing a single layer with multiple functions, total number of layers that needs processing (e.g., recessing) may be decreased. As such, the complexity of device integration and resulting complications may be reduced.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a p-FET portion having a first gate stack thereon, the first gate stack comprising a first high-k dielectric layer over the p-FET portion, a first work function (WF) metal layer over the first high-k dielectric layer, and a first niobium carbide (NbC) as a gate metal layer over the first WF layer; and   an n-FET portion having a second gate stack thereon, the second gate stack comprising a second high-k dielectric layer over the n-FET portion, and a second NbC multi-function layer over the second high-k dielectric layer.   
     
     
         2 . The semiconductor device of  claim 1 , the first gate stack further comprising a first glue layer between the first WF metal layer and the first NbC layer, and the second gate stack further comprising a second glue layer between second high-k dielectric layer and the second NbC multi-function layer. 
     
     
         3 . The semiconductor device of  claim 1 , the first gate stack further comprising a first recess formed over the first high-k dielectric layer, the first work function (WF) metal and the first niobium carbide (NbC) layer. 
     
     
         4 . The semiconductor device of  claim 3 , further comprising a first cap layer formed in the first recess. 
     
     
         5 . The semiconductor device of  claim 3 , the second gate stack further comprising a second recess formed over the second high-k dielectric layer and the second niobium carbide (NbC) multi-function layer. 
     
     
         6 . The semiconductor device of  claim 5 , further comprising a second cap layer formed in the second recess.