Metal oxide semiconductor transistor

Abstract

A MOS transistor including a silicon substrate, a first gate structure and a second gate structure disposed on the silicon substrate is provided. The first gate structure and the second gate structure each includes a high-k dielectric layer disposed on the silicon substrate, a barrier layer disposed on the high-k dielectric layer, and a work function layer disposed on and contacted with the barrier layer. The MOS transistor further includes a dielectric material spacer. The dielectric material spacer is disposed on the barrier layer of each of the first gate structure and the second gate structure and surrounding the work function layer of each of the first gate structure and the second gate structure.

What is claimed is: 
     
         1 . A MOS transistor, comprising:
 a silicon substrate;   a gate structure, disposed on the silicon substrate, the gate structure comprising:
 a high-k dielectric layer disposed on the silicon substrate; 
 a barrier layer disposed on the high-k dielectric layer; and 
 a work function layer disposed on and contacted with the barrier layer; and 
   a dielectric material spacer disposed on the barrier layer of the gate structure and surrounding the work function layer of the gate structure.   
     
     
         2 . The MOS transistor as claimed in  claim 1 , wherein the gate structure further comprises an interface layer, disposed between the high-k dielectric layer and the silicon substrate. 
     
     
         3 . The MOS transistor as claimed in  claim 2 , wherein the work function layer comprises a titanium nitride layer and a titanium aluminum layer on the titanium nitride layer. 
     
     
         4 . The MOS transistor as claimed in  claim 2 , wherein the work function layer comprises a titanium aluminum layer. 
     
     
         5 . The MOS transistor as claimed in  claim 1 , wherein the barrier layer is a titanium nitride layer. 
     
     
         6 . The MOS transistor as claimed in  claim 1 , further comprising a conductive material layer disposed on the work function layer. 
     
     
         7 . The MOS transistor as claimed in  claim 6 , wherein the conductive material layer is an aluminum layer.