Semiconductor device and method for manufacturing the same

Abstract

A semiconductor device includes a gate insulating film formed on a semiconductor substrate, and a gate electrode formed on the gate insulating film. Nitrogen is introduced into the gate insulating film, and the nitrogen concentration distribution thereof has a peak near the surface of the gate insulating film or near the center of the gate insulating film in the thickness direction. The peak value of nitrogen concentration in the gate insulating film is equal to or greater than 10 atm % and less than or equal to 40 atm %.

1 . A semiconductor device comprising: 
 a semiconductor substrate partitioned into a first region, a second region and a third region;    a first gate insulating film on the first region;    a second gate insulating film on the second region, the second gate insulating film having a thickness thinner than that of the first gate insulating film; and    a third gate insulating film on the third region, the third gate insulating film having a thickness thinner than that of the second gate insulating film,    wherein nitrogen is introduced to the surface portion of the first gate insulating film such that the nitrogen does not reach the interface between the first gate insulating film and the semiconductor substrate; and    wherein nitrogen is introduced to the third gate insulating film such that the nitrogen reaches the interface between the third gate insulating film and the semiconductor substrate.    
   
   
       2 . The semiconductor device of  claim 1 , wherein the thickness of the first gate insulating film is equal to or greater than 3.5 nm and less than or equal to 9 nm.  
   
   
       3 . The semiconductor device of  claim 1 , wherein the thickness of the second gate insulating film is equal to or greater than 1.0 nm and less than or equal to 3.0 nm.  
   
   
       4 . The semiconductor device of  claim 1 , wherein a nitrogen concentration distribution of the first gate insulating film has a peak near a surface of the first gate insulating film in a thickness direction, and 
 a nitrogen concentration distribution of the second gate insulating film has a peak near a center of the second gate insulating film in a thickness direction.    
   
   
       5 . The semiconductor device of  claim 1 , wherein each peak value of nitrogen concentrations in the first gate insulating film and the second gate insulating film is equal to or greater than 10 atm % and less than or equal to 40 atm %.  
   
   
       6 . The semiconductor device of  claim 1 , wherein the nitrogen concentration in the second gate insulating film at an interface between the second gate insulating film and the semiconductor substrate is equal to or greater than 0.2 atm % and less than or equal to 3 atm %.