Selective nitridation of gate oxides

Abstract

A method of fabricating a semiconductor structure. The method includes forming a first feature of a first active device and a second feature of a second active device, introducing a first amount of nitrogen into the first feature of the first active device, and introducing a second amount of nitrogen into the second feature of the second active device, the second amount of nitrogen being different from the first amount of nitrogen.

1 . A semiconductor structure comprising:
 a semiconductor substrate;   a first active device formed on the substrate, the first active device having a first gate dielectric, which has a first concentration of nitrogen; and   a second active device formed on the substrate, the second active device having a second gate dielectric, which has a second concentration of nitrogen different than the first concentration of nitrogen,   wherein the second gate dielectric is thicker than the first gate dielectric.   
   
   
       2 . A semiconductor structure according to  claim 1 , wherein:
 the first gate dielectric has a first thickness susceptible to appreciable dopant diffusion and current leakage; and   the second gate dielectric has a second thickness susceptible to appreciable dopant diffusion and current leakage.   
   
   
       3 . A semiconductor structure according to  claim 2 , wherein the second concentration of nitrogen is less than the first concentration of nitrogen. 
   
   
       4 . A semiconductor structure according to  claim 3 , wherein the second active device is a p-channel field effect transistor and the first active device is an n-channel field effect transistor. 
   
   
       5 . A semiconductor structure according to  claim 1 , wherein the first dielectric gate has a first thickness being susceptible to appreciable dopant diffusion or current leakage; and the second dielectric gate having a second thickness not being susceptible to appreciable dopant diffusion or current leakage. 
   
   
       6 . A semiconductor structure according to  claim 5 , wherein the second concentration of nitrogen is less than the first concentration of nitrogen. 
   
   
       7 . A semiconductor structure according to  claim 2 , wherein the first thickness and second thickness are less than about fifty angstroms. 
   
   
       8 . A semiconductor structure according to  claim 5 , wherein the first thickness is less than about fifty angstroms; and the second thickness is about fifty angstroms or greater. 
   
   
       9 . A semiconductor structure according to  claim 1 , wherein the first concentration of nitrogen and the second concentration of nitrogen were selectively introduced by one or more processes including one of:
 rapid thermal nitridation;   furnace nitridation;   remote plasma nitridation;   decoupled plasma nitridation;   well implantation; and   polysilicon implantation.   
   
   
       10 . A semiconductor structure according to  claim 1 , wherein the first concentration of nitrogen is about 8×10 14  to 1×10 22  atoms/centimeter 2 . 
   
   
       11 . A semiconductor structure according to  claim 1 , wherein the first concentration of nitrogen is sufficient to prevent appreciable gate leakage and dopant penetration in the first dielectric gate without causing an appreciable threshold-voltage shift in the first dielectric gate. 
   
   
       12 . A semiconductor structure according to  claim 11 , wherein the second concentration of nitrogen is about 1×10 13  to 1×10 15  atoms/centimeter 2 . 
   
   
       13 . A semiconductor structure according to  claim 1 , wherein the second concentration of nitrogen is sufficient to prevent appreciable gate leakage and dopant penetration in the second dielectric gate without causing an appreciable threshold-voltage shift in the second dielectric gate. 
   
   
       14 . The semiconductor structure of  claim 1 , wherein the first gate dielectric has a first thickness and the second gate dielectric has a second thickness greater than the first thickness, and wherein the second concentration of nitrogen is less than the first concentration of nitrogen. 
   
   
       15 . The semiconductor structure of  claim 14 , wherein the first active device is a p-well and the second active device is an n-well. 
   
   
       16 . The semiconductor structure of  claim 15 , wherein the first active device is a n-FET and the second active device is an p-FET. 
   
   
       17 . The semiconductor structure of  claim 16 , wherein the first and second gate dielectrics are each an oxynitride layer. 
   
   
       18 . The semiconductor structure of  claim 14 , wherein the first and second gate dielectrics are each an oxynitride layer. 
   
   
       19 . The semiconductor structure of  claim 18 , wherein the first active device is a p-well or an n-FET and the second active device is an n-well or a p-FET. 
   
   
       20 . The semiconductor structure of  claim 19 , wherein:
 the nFET has a nitrogen enriched interface between a well and a gate of the nFET; and   the pFET has a nitrogen enriched interface between a well and a gate of the pFET.