Semiconductor device with wiring layer of low resistance

Abstract

A semiconductor device includes a polysilicon film formed directly or indirectly on a semiconductor substrate, and a refractory metal silicide film formed on the polysilicon film. The refractory metal silicide film comprises grains of refractory metal silicide. At least a portion of the grains has a maximum grain diameter equal to or larger than at least one of a film thickness of the refractory metal silicide film and a film width of the refractory metal silicide film.

What is claimed is:  
     
         1 . A semiconductor device comprising:  
 a polysilicon film formed directly or indirectly on a semiconductor substrate; and     a refractory metal silicide film formed on said polysilicon film, and     wherein said refractory metal silicide film comprises grains of refractory metal silicide, and at least a portion of said grains has a maximum grain diameter equal to or larger than at least one of a film thickness of said refractory metal silicide film and a film width of said refractory metal silicide film.    
     
     
         2 . A semiconductor device according to    claim 1   , wherein said film thickness of said refractory metal silicide is in a range of 100 to 150 nm, said film width of said refractory metal silicide is in a range of 40 to 250 nm, and said maximum grain diameter is in a range of 150 to 200 nm.  
     
     
         3 . A semiconductor device according to    claim 1   , wherein said refractory metal silicide is tungsten silicide (WSi).  
     
     
         4 . A semiconductor device according to    claim 1   , wherein said refractory metal silicide has a sheet resistance in a range of 2 to 4 Ω/□.  
     
     
         5 . A semiconductor device according to    claim 1   , further comprising a gate insulating film formed on said semiconductor substrate, said refractory metal silicide being formed on said gate insulating film, and  
 wherein said polysilicon film and said refractory metal silicide function a gate electrode of a MOS transistor and a wiring layer.    
     
     
         6 . A semiconductor device according to    claim 1   , further comprising a coverage film formed on said refractory metal silicide, for suppressing growth of said grains in a direction of said film thickness.  
     
     
         7 . A semiconductor device according to    claim 6   , wherein said coverage film is a silicon oxide film.  
     
     
         8 . A method of manufacturing a semiconductor device, comprising:  
 forming a polysilicon film formed directly or indirectly on a semiconductor substrate;     forming a refractory metal silicide film formed on said polysilicon film;     performing heat treatment such that at least a portion of grains of said refractory metal silicide film has a maximum grain diameter equal to or larger than at least one of a film thickness of said refractory metal silicide film and a film width of said refractory metal silicide film; and     patterning said polysilicon film and said refractory metal silicide after said heat treatment.    
     
     
         9 . A method according to    claim 8   , wherein said refractory metal silicide film is a tungsten silicide film.  
     
     
         10 . A method according to    claim 9   , wherein said step of forming a refractory metal silicide film includes  
 reacting tungsten and silicon with a composition ratio in a range of 1:2.0 to 1:2.2.    
     
     
         11 . A method according to    claim 8   , wherein said step of performing heat treatment includes:  
 performing a rapid thermal annealing method at a temperature equal to or higher than 950° C. for a time equal to or shorter than 60 seconds.    
     
     
         12 . A method according to    claim 11   , wherein said step of performing a rapid thermal annealing method includes:  
 performing said rapid thermal annealing method at a temperature in range of 950 to 1000° C. for a time substantially equal to 60 seconds.    
     
     
         13 . A method according to    claim 11   , wherein said step of performing a rapid thermal annealing method includes:  
 performing said rapid thermal annealing method at a temperature in range of 1000 to 1100° C. for a time substantially equal to 15  seconds.    
     
     
         14 . A method according to    claim 8   , wherein said step of performing heat treatment includes:  
 performing a rapid thermal annealing method such that said refractory metal silicide film has a sheet resistance in a range of 2 to 4 Ω/□.    
     
     
         15 . A method according to    claim 8   , wherein said step of performing heat treatment includes:  
 performing a rapid thermal annealing method such that said maximum grain diameter is in a range of 150 to 200 nm.    
     
     
         16 . A method according to    claim 8   , further comprising forming a gate insulating film on said semiconductor substrate, said refractory metal silicide being formed on said gate insulating film, and  
 wherein said polysilicon film and said refractory metal silicide function a gate electrode of a MOS transistor and a wiring layer.    
     
     
         17 . A method according to    claim 8   , further comprising forming a coverage film on said refractory metal silicide to suppress growth of said grains in a direction of said film thickness, before said heat treatment.  
     
     
         18 . A method according to    claim 17   , wherein said coverage film is a silicon oxide film.  
     
     
         19 . A method according to    claim 8   , wherein said patterning includes  
 patterning said polysilicon film and said refractory metal silicide film to have said film width in a range of 40 to 250 nm.    
     
     
         20 . A semiconductor device comprising:  
 a polysilicon film formed directly or indirectly on a semiconductor substrate; and     a refractory metal silicide film formed on said polysilicon film to have a sheet resistance in a range of 2 to 4.     
     
     
         21 . A semiconductor device according to    claim 20   , wherein said refractory metal silicide film comprises grains of refractory metal silicide, a film thickness of said refractory metal silicide is in a range of 100 to 150 nm, a film width of said refractory metal silicide is in a range of 40 to 250 nm, and a maximum grain diameter of said grains is in a range of 150 to 200 nm.  
     
     
         22 . A semiconductor device according to    claim 21   , wherein said refractory metal silicide is tungsten silicide (WSi).  
     
     
         23 . A semiconductor device according to    claim 20   , wherein said refractory metal silicide film comprises grains of refractory metal silicide, and at least a portion of said grains has a maximum grain diameter equal to or larger than at least one of a film thickness of said refractory metal silicide film and a film width of said refractory metal silicide film.