Semiconductor devices and methods of fabricating semiconductor devices

Abstract

Semiconductor devices are provided. A semiconductor device includes a substrate including first through fourth areas. Moreover, first through fourth gate insulating layers are on the first through fourth areas, respectively. Amounts of work function control materials in the first through fourth gate insulating layers, nitrogen concentrations in the first through fourth gate insulating layers, and/or thicknesses of the first through fourth gate insulating layers vary among the first through fourth gate insulating layers. Methods for fabricating semiconductor devices are also provided.

1 . A semiconductor device comprising:
 a substrate comprising first through fourth areas;   first through fourth gate insulating layers on the first through fourth areas of the substrate, respectively;   first through fourth work function layers on the first through fourth gate insulating layers, respectively; and   first through fourth gate metals on the first through fourth work function layers, respectively,   wherein first and second nitrogen concentrations of the first and second gate insulating layers, respectively, are higher than third and fourth nitrogen concentrations of the third and fourth gate insulating layers, respectively, and   wherein first and second thicknesses of the first and third gate insulating layers, respectively, are thicker than third and fourth thicknesses of the second and fourth gate insulating layers, respectively.   
     
     
         2 . The semiconductor device of  claim 1 , wherein the third and fourth nitrogen concentrations are zero. 
     
     
         3 . The semiconductor device of  claim 2 , wherein the first and second nitrogen concentrations comprise equal nitrogen concentrations. 
     
     
         4 . The semiconductor device of  claim 3 , wherein the first through fourth gate insulating layers each comprise an interface layer and a high-k layer. 
     
     
         5 . The semiconductor device of  claim 1 ,
 wherein the first and second thicknesses are equal, and   wherein the third and fourth thicknesses are equal.   
     
     
         6 . The semiconductor device of  claim 1 ,
 wherein the first through fourth gate insulating layers comprise first through fourth amounts, respectively, of a work function control material, and   wherein the first and second amounts are unequal to the third and fourth amounts.   
     
     
         7 . The semiconductor device of  claim 6 , wherein the work function control material comprises lanthanum. 
     
     
         8 . The semiconductor device of  claim 6 , wherein the work function control material comprises aluminum. 
     
     
         9 . The semiconductor device of  claim 1 ,
 wherein the first through fourth gate insulating layers, the first through fourth work function layers, and the first through fourth gate metals are included in first through fourth transistors, respectively, and   wherein the first through fourth transistors have different first through fourth threshold voltages, respectively.   
     
     
         10 . The semiconductor device of  claim 9 , wherein the second threshold voltage is higher than the third threshold voltage. 
     
     
         11 . The semiconductor device of  claim 9 , wherein the fourth threshold voltage is higher than the first threshold voltage. 
     
     
         12 . The semiconductor device of  claim 9 ,
 wherein the substrate further comprises fifth through eighth areas,   wherein the semiconductor device further comprises:
 fifth through eighth gate insulating layers on the fifth through eighth areas, respectively; 
 fifth through eighth work function layers on the fifth through eighth gate insulating layers, respectively; and 
 fifth through eighth gate metals on the fifth through eighth work function layers, respectively, 
   wherein fifth and sixth nitrogen concentrations of the fifth and sixth gate insulating layers, respectively, are higher than seventh and eighth nitrogen concentrations of the seventh and eighth gate insulating layers, respectively, and   wherein fifth and sixth thicknesses of the fifth and seventh gate insulating layers, respectively, are thicker than seventh and eight thicknesses of the sixth and eighth gate insulating layers, respectively.   
     
     
         13 . The semiconductor device of  claim 12 ,
 wherein the first through eighth gate insulating layers, the first through eighth work function layers, and the first through eighth gate metals are included in first through eighth transistors, respectively,   wherein the first through eighth transistors have first through eighth threshold voltages, respectively,   wherein the first threshold voltage is higher than the fourth threshold voltage, and   wherein the fifth threshold voltage is lower than the eighth threshold voltage.   
     
     
         14 . The semiconductor device of  claim 12 ,
 wherein the first through eighth gate insulating layers, the first through eighth work function layers, and the first through eighth gate metals are included in first through eighth transistors, respectively,   wherein the first through eighth transistors have first through eighth threshold voltages, respectively,   wherein the first threshold voltage is higher than the fourth threshold voltage, and   wherein the fifth threshold voltage is higher than the eighth threshold voltage.   
     
     
         15 - 23 . (canceled) 
     
     
         24 . A semiconductor device comprising:
 a substrate comprising first through fourth areas;   first through fourth gate insulating layers on the first through fourth areas, respectively;   first through fourth work function layers on the first through fourth gate insulating layers, respectively; and   first through fourth gate metals on the first through fourth work function layers, respectively,   wherein the first and second gate insulating layers, but not the third and fourth gate insulating layers, comprise nitrogen, and   wherein the first and third gate insulating materials comprise different first and second amounts of a work function control material, respectively.   
     
     
         25 . (canceled) 
     
     
         26 . A semiconductor device comprising:
 a substrate comprising first through fourth areas thereof, wherein the second area is between the first and third areas, and wherein the third area is between the second and fourth areas; and   first through fourth transistors on the first through fourth areas of the substrate, respectively, the first through fourth transistors comprising first through fourth gate insulating layers, respectively, and the first gate insulating layer comprising a first amount of a work function control material that is different from a second amount of the work function control material that is in one of the second through fourth gate insulating layers.   
     
     
         27 . The semiconductor device of  claim 26 , wherein the first gate insulating layer comprises a first thickness that is different from a second thickness of one of the second through fourth gate insulating layers. 
     
     
         28 . The semiconductor device of  claim 27 ,
 wherein each of the first through fourth transistors further comprises:
 a work function layer on the respective one of the first through fourth gate insulating layers; and 
 a gate metal on the work function layer, and 
   wherein the first thickness comprises a thickness of a portion of the first gate insulating layer that extends along a sidewall of the work function layer of the first transistor.   
     
     
         29 . The semiconductor device of  claim 26 , wherein the first gate insulating layer comprises a first nitrogen concentration that is different from a second nitrogen concentration of one of the second through fourth gate insulating layers. 
     
     
         30 . The semiconductor device of  claim 26 , wherein:
 the first and third gate insulating layers comprise a first thickness that is thicker than a second thickness of the second and fourth gate insulating layers;   the first and second gate insulating layers comprise a first nitrogen concentration that is higher than a second nitrogen concentration of the third and fourth gate insulating layers;   the first amount of the work function control material is smaller than the second amount of the work function control material;   the third and fourth gate insulating layers comprise the second amount of the work function control material; and   the first and second gate insulating layers comprise the first amount of the work function control material that is smaller than the second amount of the work function control material of the third and fourth gate insulating layers.