Semiconductor device having tungsten gate electrode and method for fabricating the same

Abstract

The present invention provides a semiconductor device in which the threshold voltage of NMOS and the threshold voltage of PMOS are independently controllable, and a method for fabricating the same. The method includes: forming a gate insulating film over an NMOS region and a PMOS region of a semiconductor substrate; forming a carbon-containing tungsten over the gate insulating film formed over one of the NMOS region and the PMOS region; forming a carbon-containing tungsten nitride over the gate insulating film formed over the other one of the PMOS region or the NMOS region; forming a tungsten film over the carbon-containing tungsten and the carbon-containing tungsten nitride; post-annealing the carbon-containing tungsten and the carbon-containing tungsten nitride; and etching the tungsten film, the carbon-containing tungsten, and the carbon-containing tungsten nitride, to form a gate electrode in the NMOS region and the PMOS region

1 - 15 . (canceled) 
     
     
         16 . A method for fabricating a semiconductor device, the method comprising:
 forming a gate insulating film over an entire surface of a semiconductor substrate including an NMOS region and a PMOS region;   forming a first tungsten-containing film, containing a first work function control material, over the gate insulating film formed over the NMOS region;   forming a second tungsten-containing film, containing a second work function control material, over the gate insulating film formed over the PMOS region;   post-annealing the semiconductor substrate having the first tungsten-containing film and the second tungsten-containing film formed thereon; and   etching the first tungsten-containing film and the second tungsten-containing film to form a gate electrode in the NMOS region and the PMOS region.   
     
     
         17 . The method of  claim 16 , wherein the first work function control material includes carbon. 
     
     
         18 . The method of  claim 16 , wherein the second work function control material includes carbon and nitrogen. 
     
     
         19 . The method of  claim 16 , wherein forming the first tungsten-containing film and the second tungsten-containing film comprises:
 performing an atomic layer deposition using a fluorine-free tungsten source containing carbon.   
     
     
         20 . The method of  claim 19 , wherein the first tungsten-containing film includes a fluorine-free tungsten containing carbon, and wherein forming the first tungsten-containing film further comprises:
 plasma treating the first tungsten-containing film with a hydrogen-containing material to control a carbon content of the first tungsten-containing film.   
     
     
         21 . The method of  claim 19 , wherein the second tungsten-containing film includes a fluorine-free tungsten nitride containing carbon, and wherein forming the second tungsten-containing film further comprises:
 plasma treating the second tungsten-containing film with a nitrogen-containing material to control a carbon content and a nitrogen content of the second tungsten-containing film.   
     
     
         22 . The method of  claim 16 , further comprising:
 forming a third tungsten-containing film over the first tungsten-containing film and the second tungsten-containing film.   
     
     
         23 . The method of  claim 22 , wherein forming the third tungsten-containing film comprises:
 forming a tungsten nucleation film over the first tungsten-containing film and the second tungsten-containing film; and   forming a bulk tungsten film over the tungsten nucleation film.   
     
     
         24 . A method for fabricating a semiconductor device, the method comprising:
 forming a gate insulating film over an NMOS region and a PMOS region of a semiconductor substrate;   forming a carbon-containing tungsten over the gate insulating film formed over the NMOS region;   forming a carbon-containing tungsten nitride over the gate insulating film formed over the PMOS region;   forming a tungsten film over the carbon-containing tungsten and the carbon-containing tungsten nitride;   post-annealing the carbon-containing tungsten and the carbon-containing tungsten nitride; and   etching the tungsten film, the carbon-containing tungsten, and the carbon-containing tungsten nitride, to form a gate electrode in the NMOS region and the PMOS region.   
     
     
         25 . The method of  claim 24 , wherein a carbon content of the carbon-containing tungsten is controlled such that the carbon content of the first gate electrode is about 10-15 at %. 
     
     
         26 . The method of  claim 24 , further comprising:
 controlling a carbon content and a nitrogen content of the carbon-containing tungsten nitride so that the carbon content and the nitrogen content of the second gate electrode are about 5-10 at % and about 20-30 at %, respectively.