Semiconductor device and fabricating method for the same

Abstract

The present invention is intended to provide a semiconductor device having a gate electrode free from increasing of resistance of the gate electrode, from decreasing of capacitance of the insulation film due to depletion, and from penetrating of impurity. The semiconductor device comprises a silicon layer, a gate insulating film formed on the silicon layer, a metal boron compound layer formed on the gate insulating film, and a gate electrode formed on the metal boron compound layer and containing at least silicon.

What is claimed is:  
     
         1 . A semiconductor device including a CMOS transistor having: 
 a p channel MOS transistor comprising 
 a substrate,  
 an n type silicon layer containing a source region and a drain region provided in or on the substrate and positioned apart from each other, and a channel region provided between the source region and the drain region,  
 a gate insulating film formed on the channel region of the n type silicon layer,  
 a metal boron compound layer formed on the gate insulating film, and  
 a gate electrode formed on the metal boron compound layer and containing at least silicon, and  
   an n channel MOS transistor comprising 
 a p type silicon layer containing a source region and a drain region provided in or on the substrate and positioned apart from each other, and a channel region provided between the source region and the drain region,  
 a gate insulating film formed on the p type silicon layer,  
 a metal silicide layer formed on the gate insulating film, and  
 a gate electrode formed on the metal silicide layer and containing at least silicon.  
   
     
     
         2 . The semiconductor device as stated in  claim 1 , wherein a metal contained in the metal boron compound layer and a metal contained in the metal silicide layer are the same element, and the metal is selected so that an absolute value of free energy of the metal boron compound can be greater than an absolute value of free energy of the metal silicide layer.  
     
     
         3 . The semiconductor device as stated in  claim 1 , wherein the gate electrode contains germanium.  
     
     
         4 . The semiconductor device as stated in  claim 1 , wherein the metal boron compound layer contains at least one metal selected from transition metals of group  4 , and the gate insulating film is an oxide film of silicon or of at least one metal selected from any of transition metals of group  4 , tantalum, aluminum, yttrium, lanthanum, cerium and other rare earth elements.  
     
     
         5 . The semiconductor device as stated in  claim 2 , wherein the metal is titanium.  
     
     
         6 . The semiconductor device as stated in  claim 1 , wherein atomic composition ratio is metal:boron=1:1.5 to 2.  
     
     
         7 . The semiconductor device as stated in  claim 6 , wherein the metal is titanium.  
     
     
         8 . A semiconductor device comprising 
 a silicon layer containing a source region and a drain region located apart from each other, and a channel region interposed between the source region and the drain region,    a gate insulating film formed on the silicon layer,    a metal boron compound layer formed on the gate insulating film, and    a gate electrode formed on the metal boron compound layer and containing at least silicon.    
     
     
         9 . A fabricating method for a semiconductor device comprising: 
 forming a gate insulating film on a silicon substrate,    forming a metallic thin film on the gate insulating film,    forming a thin film containing at least silicon on the metallic thin film,    adding boron to at least a part of the thin film,    forming a metal silicide layer by reacting the metallic thin film to a part of the thin film, and    forming a metal boron compound layer by reacting a part of the metal silicide layer to boron.    
     
     
         10 . A fabricating method for a semiconductor device comprising: 
 forming a gate insulating film on a silicon substrate,    forming a metallic thin film on the gate insulating film,    forming a thin film containing at least silicon on the metallic thin film,    adding boron to a first region of the thin film,    adding n type dopant to a second region of the thin film,    forming a metal silicide layer by reacting the metallic thin film to a part of the thin film, and    forming a metal boron compound layer by reacting a part of the metal silicide layer in the first region to boron.    
     
     
         11 . A fabricating method for a semiconductor device comprising: 
 forming a gate insulating film added with a metal on a silicon substrate,    forming a thin film containing at least silicon on the gate insulating film,    adding boron to a first region of the thin film,    adding an n type dopant to a second region of the thin film,    forming a metal silicide layer by reacting the metal added to the surface of the gate insulating film to a part of the thin film, and    forming a metal boron compound layer by reacting a part of the metal silicide layer in the first region to boron.    
     
     
         12 . A fabricating method for a semiconductor device comprising: 
 forming a gate insulating film of metal oxide on a silicon substrate,    reducing a surface of the gate insulating film,    forming a thin film containing at least silicon on the gate insulating film,    adding boron to a first region of the thin film,    adding an n type dopant to a second region of the thin film,    forming a metal silicide layer by reacting a reduced metal existing on a surface of the gate insulating film to a part of the thin film, and    forming a metal boron compound layer by reacting a part of the metal silicide layer in the first region to boron.    
     
     
         13 . The fabricating method for a semiconductor device as stated in  claim 10 , wherein the thin film contains germanium.  
     
     
         14 . The fabricating method for a semiconductor device as stated in  claim 10 , wherein the metal boron compound layer contains at least one metal selected from transition metals of group  4 , and the gate insulating film is an oxide film of silicon or of at least one metal selected from any of transition metals of group  4 , tantalum, aluminum, yttrium, lanthanum, cerium and other rare earth elements.  
     
     
         15 . The fabricating method for a semiconductor device as stated in  claim 10 , wherein the metal is titanium.  
     
     
         16 . The fabricating method for a semiconductor device as stated in  claim 10 , wherein atomic composition ratio of the metal boron compound layer is metal:boron=1:1.5 to 2.  
     
     
         17 . The fabricating method for a semiconductor device as stated in  claim 10 , wherein the metal is titanium.