Metal gate mosfet by full semiconductor metal alloy conversion

Abstract

A MOSFET structure and method of forming is described. The method includes forming a metal-containing layer that is thick enough to fully convert the semiconductor gate stack to a semiconductor metal alloy in a first MOSFET type region but only thick enough to partially convert the semiconductor gate stack to a semiconductor metal alloy in a second MOSFET type region. In one embodiment, the gate stack in a first MOSFET region is recessed prior to forming the metal-containing layer so that the height of the first MOSFET semiconductor stack is less than the height of the second MOSFET semiconductor stack. In another embodiment, the metal-containing layer is thinned over one MOSFET region relative to the other MOSFET region prior to the conversion process.

1 - 13 . (canceled)  
     
     
         14 . A semiconductor structure comprising: 
 a first type MOSFET device comprising a fully-converted semiconductor metal alloy gate conductor; and    a second type MOSFET device comprising a partially-converted semiconductor metal alloy gate conductor including a lower gate conductor portion comprising a semiconductor layer and an upper semiconductor metal alloy gate conductor portion atop said lower gate conductor portion,    wherein said fully-converted semiconductor metal alloy gate conductor of said first type MOSFET device has a height less than the height of said partially-converted semiconductor metal alloy gate conductor of said second type MOSFET device.    
     
     
         15 . The semiconductor structure of  claim 14  wherein said first type MOSFET device and said second type MOSFET device are spaced apart at a distance less than 200 nm.  
     
     
         16 . The semiconductor structure of  claim 14  wherein said fully-converted semiconductor metal alloy gate conductor of said first type MOSFET device and said upper semiconductor metal alloy gate conductor portion of said second type MOSFET comprise nickel silicide.  
     
     
         17 . The semiconductor structure of  claim 14  formed by a method comprising the steps: 
 providing a structure comprising a gate stack in a first type MOSFET region and a gate stack in a second type MOSFET region, where said gate stacks each comprise a semiconductor layer, and said structure further comprising a planarized dielectric layer formed over said gate stacks in said first type and second type MOSFET regions;    removing portions of said planarized dielectric layer to expose said semiconductor layers of said gate stacks;    forming a metal-containing layer in contact with said exposed portions of said semiconductor layers of said gate stacks, wherein said metal-containing layer is thick enough to fully convert to a semiconductor metal alloy said semiconductor layer of said gate stack in said first type MOSFET region but not thick enough to fully convert to a semiconductor metal alloy said semiconductor layer of said gate stack in said second type MOSFET region;    forming a fully converted gate conductor from said metal-containing layer in contact with said semiconductor layer of said gate stack in said first type MOSFET region while forming a partially converted gate conductor from said metal-containing layer in contact with said semiconductor layer of said gate stack in said second type MOSFET region.    
     
     
         18 . The semiconductor structure of  claim 17  formed by said method further comprising, prior to forming said metal-containing layer, recessing said semiconductor layer of said gate stack in said first type MOSFET region to a height that is less than the height of said semiconductor layer of said gate stack in said second type MOSFET region.  
     
     
         19 . (canceled)  
     
     
         20 . The structure of  claim 14  wherein said first type MOSFET device is an nFET device and said second type MOSFET device is a pFET device.