Transition metal alloys for use as a gate electrode and devices incorporating these alloys

Abstract

Embodiments of a transition metal alloy having an n-type or p-type work function that does not significantly shift at elevated temperature. The disclosed transition metal alloys may be used as, or form a part of, the gate electrode in a transistor. Methods of forming a gate electrode using these transition metal alloys are also disclosed.

1 . A method comprising:
 depositing a layer of insulating material on a substrate; and   depositing a layer of an alloy over the insulating layer, the alloy including
 approximately 20 to 50 atomic percent of a transition metal, the transition metal selected from a group consisting of titanium, zirconium, tantalum, and hafnium, 
 approximately 30 to 60 atomic percent of carbon, and 
 up to approximately 20 atomic percent of aluminum. 
   
     
     
         2 . The method of  claim 1 , wherein the alloy has a work function in a range of approximately 3.8 eV to 4.4 eV. 
     
     
         3 . The method of  claim 2 , further comprising subjecting the alloy layer to a temperature up to approximately 900° Celsius, wherein the work function does not significantly shift at the temperature. 
     
     
         4 . The device of  claim 1 , further comprising subjecting the alloy layer to a temperature up to approximately 900° Celsius, wherein the alloy does not react substantially with the insulating material. 
     
     
         5 . The method of  claim 1 , wherein the alloy layer is deposited by one of chemical vapor deposition, physical vapor deposition, and atomic layer deposition. 
     
     
         6 . The method of  claim 1 , further comprising adjusting the composition of the alloy during deposition of the alloy layer. 
     
     
         7 . The method of  claim 1 , wherein the alloy further includes up to 5 atomic percent of a residual material, the residual material comprising at least one of oxygen, nitrogen, and chloride. 
     
     
         8 . The method of  claim 1 , further comprising depositing a layer of a conductive material over the alloy layer. 
     
     
         9 . The method of  claim 8 , wherein the conductive material comprises one of aluminum and poly-silicon. 
     
     
         10 . The method of  claim 8 , wherein the thickness of the allow layer is between approximately 50 and 100 Angstroms, and the thickness of the conductive material layer is between approximately 500 and 2000 Angstroms. 
     
     
         11 . The method of  claim 8 , wherein the alloy layer functions as at least one of a barrier layer and an etch stop. 
     
     
         12 . The method of  claim 1 , further comprising etching the layer of alloy and the layer of insulating material to form a gate electrode stack. 
     
     
         13 . The method of  claim 12 , further comprising forming source and drain regions in the substrate.