Lowering tungsten resistivity by replacing titanium nitride with titanium silicon nitride

Abstract

Semiconductor devices, methods and apparatus for forming the same are provided. The semiconductor device includes a substrate having a source and drain region and a gate electrode stack on the substrate between the source and drain regions. The gate electrode stack includes a conductive film layer on a gate dielectric layer, a refractory metal silicon nitride film layer on the conductive film layer, and a tungsten film layer on the refractory metal silicon nitride film layer. In one embodiment, the method includes positioning a substrate within a processing chamber, wherein the substrate includes a source and drain region, a gate dielectric layer between the source and drain regions, and a conductive film layer on the gate dielectric layer. The method also includes depositing a refractory metal silicon nitride film layer on the conductive film layer and depositing a tungsten film layer on the refractory metal silicon nitride film layer.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a substrate having a source and drain region; and   a gate electrode stack on the substrate between the source and drain regions; the gate electrode stack comprising:
 a conductive film layer on a gate dielectric layer; 
 a refractory metal silicon nitride film layer on the conductive film layer; and 
 a tungsten film layer on the refractory metal silicon nitride film layer. 
   
     
     
         2 . The semiconductor device of  claim 1 , wherein the refractory metal silicon nitride film layer is titanium silicon nitride (TiSiN). 
     
     
         3 . The semiconductor device of  claim 1 , wherein the tungsten film layer has thickness from about 450 Å to 550 Å and the refractory metal silicon nitride film layer has a thickness from about 20 Å to about 500 Å. 
     
     
         4 . The semiconductor device of  claim 2 , wherein the resistivity of the tungsten film layer in the gate electrode stack is between about 10 μohms-cm and 14 μohms-cm. 
     
     
         5 . A method of forming a gate electrode stack, comprising:
 positioning a substrate within a processing chamber, wherein the substrate comprises a source and drain region, a gate dielectric layer between the source and drain regions, and a conductive film layer on the gate dielectric layer;   forming a refractory metal silicon nitride film layer on the conductive film layer; and   forming a tungsten film layer on the refractory metal silicon nitride film layer.   
     
     
         6 . The method of  claim 5 , wherein the formation processes are performed in-situ. 
     
     
         7 . The method of  claim 5 , wherein the refractory metal silicon nitride film layer is titanium silicon nitride (TiSiN). 
     
     
         8 . The method of  claim 7 , wherein the resistivity of the tungsten film layer in the gate electrode stack is between about 10 μohms-cm and 14 μohms-cm. 
     
     
         9 . The method of  claim 7 , wherein the refractory metal silicon nitride film layer is formed using at least one of a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process, and an atomic layer deposition (ALD) process. 
     
     
         10 . A method of depositing a tungsten thin film, comprising:
 forming a plasma in a processing region of a chamber using an RF or DC power supply coupled to a titanium silicon alloy target in the chamber, the target having a first surface that is in contact with the processing region of the chamber and a second surface that is opposite the first surface;   delivering energy to a plasma formed in a processing region of a chamber, wherein delivering energy comprises delivering RF power from an RF power supply to a target or delivering DC power from a DC power supply to the target;   rotating a magnetron about the center point of the target,   biasing the substrate support with an RF power supply;   flowing a nitrogen-containing gas into the processing region; and   depositing a tungsten silicon nitride film layer on a substrate positioned on the substrate support in the chamber.   
     
     
         11 . The method of  claim 10 , wherein the magnetron is disposed adjacent the second surface of the target, the magnetron comprising:
 an outer pole comprising a plurality of magnets; and   an inner pole comprising a plurality of magnets, wherein the outer and inner poles form a closed-loop magnetron assembly.   
     
     
         12 . The method of  claim 11 , wherein the ratio of the magnetic fields generated by the outer and inner poles is between about 1.56 and about 0.57. 
     
     
         13 . The method of  claim 10 , further comprising heating a substrate support in the chamber. 
     
     
         14 . The method of  claim 10  wherein the processing region is pressurized from about 2.5 mTorr to about 6.5 mTorr. 
     
     
         15 . The method of  claim 13 , wherein the temperature of the substrate support is from about 50° C. to about 900° C. 
     
     
         16 . The method of  claim 10 , wherein the frequency of the RF power supply coupled to the target is greater than the frequency of the RF power supply coupled to the substrate support. 
     
     
         17 . The method of  claim 10 , wherein the DC power source is set from 5.0 kW to 50 W and the RF power source coupled to the substrate support is set from 5.0 kW to 50 kW.