Silicon carbide semiconductor device and method of manufacturing silicon carbide semiconductor device

Abstract

In a silicon carbide semiconductor device in which a contact electrode is formed on a single-crystal silicon carbide semiconductor substrate, a barrier metal (titanium nitride layer) covers an interlayer insulating film in a region other than a contact hole, and a contact electrode of a predetermined electrode material is formed only in a region on the silicon carbide semiconductor substrate in the contact hole opened in the interlayer insulating film on the silicon carbide semiconductor substrate. A top of the barrier metal is covered by a metal electrode (wiring layer) and no nickel metal aggregates are present between the barrier metal and the metal electrode.

What is claimed is: 
     
         1 . A silicon carbide semiconductor device comprising:
 a single-crystal silicon carbide semiconductor substrate;   an interlayer insulating film formed on the silicon carbide semiconductor substrate, the interlayer insulating film having a contact hole;   a barrier metal layer formed on the interlayer insulating film outside of the contact hole and on a side surface of the contact hole;   a contact electrode disposed on a bottom surface of the contact hole; and   a wiring layer covered over the barrier metal layer, a boundary between the barrier metal layer and the wiring layer being free of aggregates of nickel metal.   
     
     
         2 . The silicon carbide semiconductor device according to  claim 1 , wherein the contact electrode is made of nickel silicide. 
     
     
         3 . The silicon carbide semiconductor device according to  claim 1 , wherein the barrier metal is made of a nitride containing one or more of titanium, zirconium, tantalum, and tungsten. 
     
     
         4 . The silicon carbide semiconductor device according to  claim 1 , wherein the barrier metal has a surface roughness of 50 nm or less, said surface roughness being a surface roughness on a microscopic scale that excludes an effect of differences in levels on a macroscopic scale originating in a surface structure of a gate electrode. 
     
     
         5 . A method of manufacturing a silicon carbide semiconductor device in which a contact electrode is formed on a single-crystal silicon carbide semiconductor substrate, the method comprising:
 forming a contact hole in an interlayer insulating film formed on the silicon carbide semiconductor substrate;   forming a barrier metal layer on the interlayer insulating film outside of the contact hole and on a side surface of the contact hole;   forming an electrode layer of an electrode material on the barrier metal layer and a bottom portion of the contact hole;   thermal annealing the silicon carbide semiconductor substrate thereafter to form a contact electrode made of a nickel silicide in the bottom portion of the contact hole and scatter nickel metal aggregates in a region other than the bottom portion of the contact hole; and   immersing the silicon carbide semiconductor substrate thereafter in a chemical solution in which nickel is soluble to dissolve and remove the nickel metal aggregates.   
     
     
         6 . The method of manufacturing a silicon carbide semiconductor device according to  claim 5 , wherein the chemical solution includes any of nitric acid, hydrochloric acid, and sulfuric acid. 
     
     
         7 . The method of manufacturing a silicon carbide semiconductor device according to  claim 5 , wherein the electrode layer is comprised of pure nickel or an alloy containing nickel. 
     
     
         8 . The method of manufacturing a silicon carbide semiconductor device according to  claim 5 , wherein the barrier metal layer is comprised of a nitride containing one or more of titanium, zirconium, tantalum, and tungsten.