Deposition of tungsten nitride by plasma enhanced chemical vapor deposition

Abstract

A layer of tungsten nitride is deposited on the upper surface of a wafer. The deposition is performed by providing a gaseous mixture and providing energy to the gaseous mixture to form a plasma. The gaseous mixture includes a first gaseous composition containing tungsten and a second gaseous composition containing nitrogen and hydrogen. The second gaseous composition is one that does not have a gas phase reaction with the first gaseous composition to form tungsten nitride, unless energy is provided to the gaseous mixture. The first gaseous composition may be tungsten hexafluoride (WF 6 ). The gaseous mixture may be infused with energy to form a plasma by providing it with energy from an rf signal. In the plasma, the nitrogen dissociates into nitrogen ions, and the tungsten separates from the fluorine. The nitrogen ions and tungsten then combine to form tungsten nitride (W 2 N), which deposits on the wafer's upper surface.

What is claimed is:  
     
         1 . A method for depositing a layer of material on an upper surface of a partially formed integrated circuit in a processing chamber, said method comprising the steps of: 
 (a) providing a gaseous mixture in the processing chamber, wherein said gaseous mixture includes a first gaseous composition containing tungsten and a second gaseous composition containing nitrogen and hydrogen, wherein said second gaseous composition does not have a gas phase reaction with said first gaseous composition to form tungsten nitride, unless energy is provided to said gaseous mixture; and    (b) providing energy to said gaseous mixture in the processing chamber to form a plasma.    
     
     
         2 . The method of    claim 1   , wherein said first gaseous composition includes tungsten hexafluoride.  
     
     
         3 . The method of    claim 2   , wherein said first gaseous composition consists of tungsten hexafluoride.  
     
     
         4 . The method of    claim 3   , wherein said second gaseous composition consists of hydrogen and nitrogen.  
     
     
         5 . The method of    claim 2   , wherein said first gaseous composition is provided at a flow rate in a range of 1 sccm to 100 sccm.  
     
     
         6 . The method of    claim 5    wherein said hydrogen is provided at a flow rate in a range of 1 sccm to 5,000 sccm and said nitrogen is provided at a flow rate in a range of 1 sccm to 5,000 sccm.  
     
     
         7 . The method of    claim 6   , wherein said plasma is generated for a time in a range of 5 seconds to 600 seconds.  
     
     
         8 . The method of    claim 2   , wherein said gaseous mixture includes argon.  
     
     
         9 . The method of    claim 8    wherein said argon is provided at a flow rate in a range of 1 sccm to 5,000 sccm.  
     
     
         10 . The method of    claim 1   , wherein said step (b) includes the step of: 
 providing a signal having a frequency to a first electrode on a first side of said partially formed integrated circuit.    
     
     
         11 . The method of    claim 10   , wherein a second electrode on a second side of said partially formed integrated circuit is coupled to an electrical ground.  
     
     
         12 . The method of    claim 10   , wherein said frequency is in a range of 100 KHz to 5 GHz.  
     
     
         13 . The method of    claim 1   , further including the step of: 
 (c) depositing a layer of metal on an upper surface of said layer of material, while said layer of material is in said processing chamber.    
     
     
         14 . The method of    claim 1   , further including the steps of: 
 (c) setting a pressure in said processing chamber to be within a range of 0.1 Torr to 100 Torr; and    (d) setting a temperature of said partially formed integrated circuit to be within a range of 200° C. to 600° C.    
     
     
         15 . The method of    claim 1   , wherein said layer of material is a diffusion barrier.  
     
     
         16 . The method of    claim 1   , wherein said material is tungsten nitride.  
     
     
         17 . A processor readable storage medium having program code embodied therein, said program code for controlling a chamber during a deposition of a material on a wafer, wherein said chamber includes a gas panel, a heating element, a pressure control unit, a signal source, and an electrode coupled to said signal source, said program code including: 
 a first program code, said first program code instructs a processor to provide a signal to said gas panel to cause a gaseous mixture to be provided in said chamber, wherein said gaseous mixture includes a first gaseous composition containing tungsten and a second gaseous composition containing nitrogen and hydrogen, wherein said second gaseous composition does not have a gas phase reaction with said first gaseous composition to form tungsten nitride, unless energy is provided to said gaseous mixture; and    a second program code, said second program code instructs said processor to provide a signal to said signal source to generate a signal having a frequency to be provided to said electrode to convert said gaseous mixture into a plasma.    
     
     
         18 . The processor readable storage medium of    claim 17   , wherein said program code further includes: 
 a third program code, said third program code instructs a processor to provide a signal to said heating element to cause a temperature of said wafer to be within a range of 200° C. to 600° C.; and    a fourth program code, said fourth program code instructs said processor to provide a signal to said pressure control unit to cause a pressure in said chamber to be within a range of 0.1 Torr to 100 Torr.    
     
     
         19 . The processor readable storage medium of    claim 17   , wherein said gaseous mixture contains tungsten hexafluoride, hydrogen, nitrogen, and argon.  
     
     
         20 . The processor readable storage medium of    claim 17   , wherein said frequency is in a range of 100 KHz to 5 GHz.  
     
     
         21 . The processor readable storage medium of    claim 20   , wherein said signal is provided for a time in a range of 5 seconds to 600 seconds.