Method of lateral oxidation of nfet and pfet high-k gate stacks

Abstract

A method for fabricating a semiconductor circuit includes obtaining a semiconductor structure having a gate stack of material layers including a high-k dielectric layer; oxidizing in a lateral manner the high-k dielectric layer, such that oxygen content of the high-k dielectric layer is increased first at the sidewalls of the high-k dielectric layer; and completing fabrication of a n-type field effect transistor from the gate stack after laterally oxidizing the high-k dielectric layer of the gate stack.

What is claimed is: 
     
         1 . A semiconductor structure, comprising:
 a n-type field effect transistor having a high-k dielectric layer that has higher concentration of oxygen at the sidewalls of the high-k dielectric layer than at the center of the high-k dielectric layer.   
     
     
         2 . The semiconductor structure of  claim 1 , wherein the high-k dielectric layer forms a portion of a gate stack. 
     
     
         3 . The semiconductor structure of  claim 2 , wherein the gate stack further comprises a work function conductor layer. 
     
     
         4 . The semiconductor structure of  claim 1 , wherein the oxygen in the high-k dielectric layer diffuses to a center of the high-k dielectric layer. 
     
     
         5 . The semiconductor structure of  claim 1 , wherein the high-k dielectric layer is completely laterally oxidized. 
     
     
         6 . The semiconductor structure of  claim 1 , wherein the oxygen in the high-k dielectric layer does not diffuse to a center of the high-k dielectric layer. 
     
     
         7 . The semiconductor structure of  claim 1 , wherein the high-k dielectric layer is partially laterally oxidized. 
     
     
         8 . The semiconductor structure of  claim 1 , further comprising a work-function conductor layer on the high-k dielectric layer. 
     
     
         9 . The semiconductor structure of  claim 8 , wherein the work-function conductor layer comprises oxygen. 
     
     
         10 . The semiconductor structure of  claim 9 , wherein the oxygen of the work-function conductor layer increases near sidewalls. 
     
     
         11 . A semiconductor structure, comprising:
 a n-type field effect transistor having a high-k dielectric layer that has higher concentration of oxygen at the sidewalls of the high-k dielectric layer than at the center of the high-k dielectric layer; and   a p-type field effect transistor.   
     
     
         12 . The semiconductor structure of  claim 11 , wherein the high-k dielectric layer forms a portion of a gate stack. 
     
     
         13 . The semiconductor structure of  claim 12 , wherein the gate stack further comprises a work function conductor layer. 
     
     
         14 . The semiconductor structure of  claim 11 , wherein the oxygen in the high-k dielectric layer diffuses to a center of the high-k dielectric layer. 
     
     
         15 . The semiconductor structure of  claim 11 , wherein the high-k dielectric layer is completely laterally oxidized. 
     
     
         16 . The semiconductor structure of  claim 11 , wherein the oxygen in the high-k dielectric layer does not diffuse to a center of the high-k dielectric layer. 
     
     
         17 . The semiconductor structure of  claim 11 , wherein the high-k dielectric layer is partially laterally oxidized. 
     
     
         18 . The semiconductor structure of  claim 11 , further comprising a work-function conductor layer on the high-k dielectric layer. 
     
     
         19 . The semiconductor structure of  claim 18 , wherein the work-function conductor layer comprises oxygen. 
     
     
         20 . The semiconductor structure of  claim 19 , wherein the oxygen of the work-function conductor layer increases near sidewalls.