Semiconductor device and method for fabricating the same

Abstract

A semiconductor device includes metal interconnects made from a multi-layer film composed of a first metal film formed on a semiconductor substrate with an insulating film sandwiched therebetween and a second metal film deposited on the first metal film. An interlayer insulating film having a via hole is formed on the metal interconnects. A third metal film is selectively grown on the second metal film within the via hole, so that a plug can be formed from the third metal film.

What is claimed is:  
     
         1 . A semiconductor device comprising: 
 metal interconnects made from a multi-layer film composed of a first metal film deposited on a semiconductor substrate with an insulating film sandwiched therebetween and a second metal film deposited on said first metal film;    an interlayer insulating film formed on said metal interconnects; and    a plug made from a third metal film selectively grown on said second metal film within a via hole formed in said interlayer insulating film.    
     
     
         2 . The semiconductor device of  claim 1 , 
 wherein said third metal film is grown by plating.    
     
     
         3 . The semiconductor device of  claim 1 , 
 wherein said second metal film and said third metal film are made from the same kind of metal.    
     
     
         4 . The semiconductor device of  claim 1 , 
 wherein said second metal film and said third metal film are made from a metal including copper as a principal constituent,    said third metal film is grown by plating, and    no adhesive layer is formed between said second metal film and said third metal film.    
     
     
         5 . The semiconductor device of  claim 1 , 
 wherein an air gap is formed between said metal interconnects in said interlayer insulating film.    
     
     
         6 . The semiconductor device of  claim 1 , 
 wherein said first metal film composing said metal interconnects has interconnect resistance substantially ⅕ or less of interconnect resistance of said second metal film composing said metal interconnects.    
     
     
         7 . The semiconductor device of  claim 1 , 
 wherein said first metal film composing said metal interconnects has interconnect resistance substantially equivalent to interconnect resistance of said second metal film composing said metal interconnects.    
     
     
         8 . A method for fabricating a semiconductor device comprising the steps of: 
 depositing a first metal film on a semiconductor substrate with an insulating film sandwiched therebetween;    depositing a second metal film on said first metal film;    forming an interlayer insulating film on said second metal film;    forming a via hole in said interlayer insulating film so as to expose said second metal film within said via hole;    forming a plug of a third metal film selectively grown on said second metal film within said via hole;    forming a patterned interlayer insulating film by patterning said interlayer insulating film into the shape of interconnects; and    forming metal interconnects from a multi-layer film composed of said first metal film and said second metal film by etching said multi-layer film with said plug and said patterned interlayer insulating film used as a mask.    
     
     
         9 . The method for fabricating a semiconductor device of  claim 8 , 
 wherein said third metal film is grown by plating.    
     
     
         10 . The method for fabricating a semiconductor device of  claim 8 , 
 wherein said second metal film and said third metal film are made from the same type of metal.    
     
     
         11 . The method for fabricating a semiconductor device of  claim 8 , 
 wherein said second metal film and said third metal film are made from a metal including copper as a principal constituent, and    said third metal film is grown by plating on said second metal film with no adhesive layer sandwiched therebetween.