Semiconductor device having different metal gate structures

Abstract

A semiconductor includes a channel region in a semiconductor substrate, a gate dielectric film on the channel region, and a gate on the gate dielectric film. The gate includes a doped metal nitride film, formed from a nitride of a first metal and doped with a second metal which is different from the first metal, and a conductive polysilicon layer formed on the doped metal nitride film. The gate may further include a metal containing capping layer interposed between the doped metal nitride film and the conductive polysilicon layer.

1 . A semiconductor device comprising:
 a channel region in a semiconductor substrate;   a gate dielectric film on the channel region; and   a gate formed on the gate dielectric film, the gate comprising a doped metal nitride film, formed from a nitride of a first metal and doped with a second metal which is different from the first metal, and a conductive polysilicon layer formed on the doped metal nitride film.   
     
     
         2 . The semiconductor device of  claim 1 , wherein the gate further comprises a metal containing capping layer interposed between the doped metal nitride film and the conductive polysilicon layer. 
     
     
         3 . The semiconductor device of  claim 2 , wherein the metal containing capping layer comprises a metal, a metal oxide or a metal nitride. 
     
     
         4 . The semiconductor device of  claim 2 , wherein the metal containing capping layer comprises aluminum oxide or aluminum nitride. 
     
     
         5 . The semiconductor device of  claim 1 , wherein the gate dielectric film comprises:
 an interface layer positioned directly on the channel region and comprises a low dielectric constant film having a first dielectric constant; and   a high dielectric constant film positioned on the interface layer and having a second dielectric constant greater than the first dielectric constant.   
     
     
         6 . The semiconductor device of  claim 5 , wherein the interface layer comprises at least one of a silicon oxide film, a silicon oxynitride film and a silicate film. 
     
     
         7 . The semiconductor device of  claim 5 , wherein the high dielectric constant film comprises HfO 2 , Al 2 O 3  or a combination including these materials. 
     
     
         8 . The semiconductor device of  claim 1 , wherein the doped metal nitride film is an aluminum-doped TaN film. 
     
     
         9 . The semiconductor device of  claim 1 , wherein the doped metal nitride film is a TaN film doped with a first element comprising aluminum and a second element comprising at least one of oxygen and nitride. 
     
     
         10 . The semiconductor device of  claim 1 , wherein the doped metal nitride film is a TaN film doped with a lanthanum-based element. 
     
     
         11 . The semiconductor device of  claim 1 , wherein the doped metal nitride film is a TaN film doped with a first element comprising a lanthanum-based material and a second element comprising at least one of oxygen and nitride.