Etching metal silicides and germanides

Abstract

A metal silicide may be selectively etched by converting the metal silicide to a metal silicate. This may be done using oxidation. The metal silicate may then be removed, for example, by wet etching. A non-destructive low pH wet etchant may be utilized, in some embodiments, with high selectivity by dissolution.

1 . a semiconductor structure comprising: 
 a substrate;    a polysilicon layer over said substrate; and    a metal silicate formed on said polysilicon layer.    
   
   
       2 . The structure of  claim 1  wherein said polysilicon is a polysilicon gate electrode.  
   
   
       3 . The structure of  claim 2  including a sidewall spacer on said polysilicon gate electrode.  
   
   
       4 . The structure of  claim 3  including a source and drain formed adjacent said gate electrode.  
   
   
       5 . The structure of  claim 4  including a gate oxide under said gate electrode.  
   
   
       6 . A semiconductor structure comprising: 
 a substrate;    a layer over said substrate; and    a metal germinate formed on said layer.    
   
   
       7 . The structure of  claim 6  wherein said layer is a gate electrode.  
   
   
       8 . The structure of  claim 7  including a sidewall spacer on said gate electrode.  
   
   
       9 . The structure of  claim 8  including a source and drain formed adjacent said gate electrode.  
   
   
       10 . The structure of  claim 9  including a gate oxide under said gate electrode.