Fabrication of via contacts having dual silicide layers

Abstract

A method is provided for fabricating a via contact structure contacting a single-crystal semiconductor diffusion region at a top surface of a substrate. In such method, a first layer is formed in contact with the diffusion region at the top surface, the first layer consisting essentially of a silicide of a first metal. A dielectric region is formed to overlie the first layer. An opening is etched in the dielectric region extending through the first layer to the diffusion region. A second layer is formed to line the opening, the second layer including a second metal. Thereafter, a conductor is deposited within the opening over the second layer, and the substrate is heated to cause the second metal to form a silicide at the top surface.

1 . A method of forming a conductive via contacting a single-crystal semiconductor diffusion region at a top surface of a substrate, comprising: 
 forming a first layer in contact with said diffusion region at said top surface, said first layer consisting essentially of a silicide of a first metal;    forming a dielectric region overlying said first layer;    etching an opening in said dielectric region extending through said first layer to said diffusion region;    forming a second layer lining said opening, said second layer including a second metal;    depositing a conductor in said opening over said second layer; and    heating said substrate to cause said second metal to form a silicide at said top surface.    
   
   
       2 . The method as claimed in  claim 1 , wherein said step of depositing a conductor includes depositing a diffusion barrier layer within said opening to overlie said second layer and depositing a third layer including a third metal within said opening over said diffusion barrier layer.  
   
   
       3 . The method as claimed in  claim 1 , wherein said first metal is selected from the group consisting of cobalt (Co), molybdenum (Mo), niobium (Nb), nickel (Ni), palladium (Pd), platinum (Pt), tantalum (Ta), titanium (Ti), vanadium (V) and tungsten (W).  
   
   
       4 . The method as claimed in  claim 12 , wherein said second layer is deposited to a thickness greater than about 30 angstroms (Å) at a point of contact with said top surface.  
   
   
       5 . The method as claimed in claim  13 , wherein said second metal is selected from the group consisting of titanium (Ti), nickel (Ni), platinum (Pt), cobalt (Co), tantalum (Ta) and tungsten (W).  
   
   
       6 . The method as claimed in  claim 5 , wherein said second metal is deposited to a thickness of about 80 angstroms (Å) or less at said point of contact with said top surface.  
   
   
       7 . The method as claimed in  claim 2 , wherein said diffusion barrier layer includes a metal nitride.  
   
   
       8 . The method as claimed in  claim 7 , wherein said metal nitride includes titanium nitride (TiN).  
   
   
       9 . The method as claimed in  claim 8 , wherein said diffusion barrier layer is deposited by chemical vapor deposition (CVD).  
   
   
       10 . The method as claimed in  claim 9 , wherein said third metal includes tungsten (W).  
   
   
       11 . The method as claimed in  claim 10 , wherein said third layer is deposited by chemical vapor deposition (CVD).  
   
   
       12 . A method of forming a conductive via contacting a single-crystal semiconductor diffusion region at a top surface of a substrate, comprising: 
 forming a first layer in contact with said diffusion region at said top surface, said first layer consisting essentially of a silicide of a first metal;    forming a dielectric region overlying said first layer;    etching an opening in said dielectric region extending through said first layer to said diffusion region;    forming a second layer lining said opening, said second layer including a second metal;    depositing a diffusion barrier layer overlying said second layer within said opening;    depositing a third layer including a third metal over said diffusion barrier layer within said opening; and    heating said substrate to cause said second metal to form a silicide at said top surface.