Replacement gate structures for semiconductor devices

Abstract

The present disclosure is generally directed to various replacement gate structures for semiconductor devices. One illustrative gate structure disclosed herein includes, among other things, a gate insulation layer and a layer of gate electrode material with a substantially horizontal portion having a first thickness and a substantially vertical portion having a second thickness that is less than the first thickness. Furthermore, the substantially horizontal portion of the layer of gate electrode material is positioned adjacent to a bottom of the replacement gate structure and above at least a portion of the gate insulation layer, and the substantially vertical portion is positioned adjacent to sidewalls of the replacement gate structure.

1 .- 22 . (canceled) 
     
     
         23 . A replacement gate structure, comprising:
 a gate insulation layer; and   a layer of gate electrode material comprising a substantially horizontal portion having a first thickness and a substantially vertical portion having a second thickness that is less than said first thickness, wherein said substantially horizontal portion is positioned adjacent to a bottom of said replacement gate structure and above at least a portion of said gate insulation layer, and wherein said substantially vertical portion is positioned adjacent to sidewalls of said replacement gate structure.   
     
     
         24 . The replacement gate structure of  claim 23 , wherein said second thickness is equal to or less than approximately one-half of said first thickness. 
     
     
         25 . The replacement gate structure of  claim 23 , wherein said first thickness is approximately 4-5 nm and said second thickness is approximately 1-2 nm. 
     
     
         26 . The replacement gate structure of  claim 23 , wherein said layer of gate electrode material comprises a first metal layer and a second metal layer formed on said first metal layer. 
     
     
         27 . The replacement gate structure of  claim 26 , wherein a thickness of a substantially horizontal portion of said first metal layer is greater than a thickness of a substantially vertical portion of said first metal layer and a thickness of a substantially horizontal portion of said second metal layer is greater than a thickness of a substantially vertical portion of said second metal layer. 
     
     
         28 . The replacement gate structure of  claim 23 , further comprising a conductive fill material positioned above said substantially horizontal portion of said layer of gate electrode material and adjacent to said substantially vertical portion of said layer of gate electrode material. 
     
     
         29 . The replacement gate structure of  claim 28 , wherein said conductive fill material comprises at least one of copper, aluminum and titanium. 
     
     
         30 . The replacement gate structure of  claim 23 , wherein said gate insulation layer comprises a substantially vertical portion that is positioned adjacent to said substantially vertical portion of said layer of gate electrode material. 
     
     
         31 . The replacement gate structure of  claim 23 , wherein said gate insulation layer comprises a high-k dielectric material having a dielectric constant greater than approximately 10. 
     
     
         32 . The replacement gate structure of  claim 31 , wherein said high-k dielectric material comprises at least one of tantalum oxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ), zirconium oxide (ZrO 2 ), titanium oxide (TiO 2 ), aluminum oxide (Al 2 O 3 ), and hafnium silicate (HfSiO x ). 
     
     
         33 . The replacement gate structure of  claim 23 , wherein said layer of gate electrode material comprises a work function adjusting metal layer. 
     
     
         34 . The replacement gate structure of  claim 33 , wherein said work function adjusting metal layer comprises at least one of titanium (Ti), titanium-nitride (TiN), titanium-aluminum (TiAl), aluminum (Al), aluminum nitride (AlN), tantalum (Ta), tantalum nitride (TaN), tantalum carbide (TaC), tantalum carbonitride (TaCN), tantalum silicon nitride (TaSiN) and tantalum silicide (TaSi). 
     
     
         35 . A replacement metal gate structure of a transistor device, the replacement metal gate structure comprising:
 a gate insulation layer comprising a high-k dielectric material, said gate insulation layer comprising a substantially horizontal portion positioned above a channel region of said transistor device and a substantially vertical portion positioned along sidewalls of said replacement metal gate structure;   a first metal layer comprising a substantially horizontal portion positioned above said substantially horizontal portion of said gate insulation layer and a substantially vertical portion positioned adjacent to said substantially vertical portion of said gate insulation layer, wherein a thickness of said substantially vertical portion of said first metal layer is less than or equal to approximately one-half of a thickness of said substantially horizontal portion of said first metal layer; and   a conductive metal gate electrode fill material positioned above said substantially horizontal portion of said first metal layer and adjacent to said substantially vertical portion of said first metal layer.   
     
     
         36 . The replacement metal gate structure of  claim 35 , wherein said first metal layer comprises a work function adjusting material layer. 
     
     
         37 . The replacement metal gate structure of  claim 35 , wherein said thickness of said substantially vertical portion of said first metal layer is approximately 1-2 nm. 
     
     
         38 . The replacement metal gate structure of  claim 35 , further comprising a second metal layer positioned on said first metal layer. 
     
     
         39 . The replacement metal gate structure of  claim 38 , wherein said second metal layer comprises a substantially horizontal portion having a first layer thickness and a substantially vertical portion having a second layer thickness that is less than said first layer thickness. 
     
     
         40 . The replacement metal gate structure of  claim 39 , wherein said second layer thickness is less than approximately one-half of said first layer thickness. 
     
     
         41 . The replacement metal gate structure of  claim 35 , wherein said conductive metal gate electrode fill material comprises one of copper, titanium and aluminum.