Reducing gate dielectric material to form a metal gate electrode extension

Abstract

In a metal gate replacement process, a cup-shaped gate metal oxide dielectric may have vertical portions that may be exposed to a reduction reaction. As a result of the reduction reaction, the vertical portions may be converted to metal, which adds to the existing gate electrode. In some cases, removing the vertical dielectric portions reduces fringe capacitance and may also advantageously slightly increased underdiffusion without adding heat, in some embodiments.

1 . A semiconductor structure comprising: 
 a semiconductor substrate;    a metal oxide gate dielectric over said substrate including an oxide of a first metal; and    a metal gate electrode over said gate dielectric, said gate electrode including a first metal portion and a lateral metal portion, said lateral metal portion of the first metal.    
   
   
       2 . The structure of  claim 1  wherein said lateral metal portion is substantially transverse to said metal oxide gate dielectric.  
   
   
       3 . The structure of  claim 1  including a spacer around said metal gate electrode.  
   
   
       4 . The structure of  claim 1  wherein said first metal portion and said lateral metal portion are formed of different metals.  
   
   
       5 . The structure of  claim 1  wherein said first metal portion and said lateral metal portion are formed of the same metal.  
   
   
       6 . The structure of  claim 1  wherein said lateral metal portion is an extension of said first metal portion.