Plasma treatment for cooper oxide reduction

Abstract

The present invention provides an in situ plasma reducing process to reduce oxides or other contaminants, using a compound of nitrogen and hydrogen, typically ammonia, at relatively low temperatures prior to depositing a subsequent layer thereon. The adhesion characteristics of the layers are improved and oxygen presence is reduced compared to the typical physical sputter cleaning process of an oxide layer. This process may be particularly useful for the complex requirements of a dual damascene structure, especially with copper applications.

1 . A method of removing oxides on a substrate, comprising: 
 a) introducing a reducing agent comprising nitrogen and hydrogen into a chamber;    b) initiating a plasma in the chamber;    c) exposing an oxide to the reducing agent.    
     
     
         2 . The method of    claim 1   , wherein the reducing agent comprises ammonia.  
     
     
         3 . The method of    claim 1   , wherein a pressure in the chamber is from about 1 to about 9 mTorr.  
     
     
         4 . The method of    claim 1   , wherein the plasma is initiated by providing a power density of about 1.4 to 14.3 watts per square centimeter to the chamber.  
     
     
         5 . The method of    claim 1   , wherein a substrate temperature is maintained from about 100° to about 450° C. while exposing the oxide to the reducing agent.  
     
     
         6 . The method of    claim 1   , wherein ammonia is introduced into the chamber at a rate of about 100 to about 1000 sccm.  
     
     
         7 . The method of    claim 1   , further comprising introducing a carrier gas into the chamber.  
     
     
         8 . The method of    claim 1   , wherein a pressure in the chamber is from about 1 to about 9 mTorr, an RF generator provides a power density from about 1.4 to about 14.3 watts per square centimeter, a substrate temperature is maintained from about 100° to about 450° C., and ammonia is introduced into the chamber at a flow rate of about 100 to about 1000 sccm.  
     
     
         9 . The method of    claim 8    further comprising introducing a carrier gas into the chamber.  
     
     
         10 . A method of removing contaminants on a surface, comprising: 
 a) initiating a plasma in a chamber with a reducing agent; and    b) exposing at least a portion of a surface having a reducible contaminant to the reducing agent.    
     
     
         11 . The method of    claim 10   , wherein the reducible contaminant comprises an oxide.  
     
     
         12 . The method of    claim 10   , wherein the reducing agent comprises ammonia.  
     
     
         13 . The method of    claim 11   , wherein the reducing agent comprises ammonia.  
     
     
         14 . The method of    claim 10   , wherein a pressure in the chamber is from about 1 to about 9 mTorr.  
     
     
         15 . The method of    claim 10   , wherein the plasma is initiated by providing a power density of about 1.4 to about 14.3 watts per square centimeter to the chamber.  
     
     
         16 . The method of    claim 10   , wherein a surface temperature is maintained from about 100° to about 450° C. while exposing the oxide to the reducing agent.  
     
     
         17 . The method of    claim 10   , wherein ammonia is introduced into the chamber at a flow rate of about 100 to about 1000 sccm.  
     
     
         18 . The method of    claim 10   , further comprising in situ depositing an adjacent layer on the substrate after the oxide has been exposed to the reducing agent.  
     
     
         19 . A reduced contaminant substrate, comprising: 
 a) a substrate;    b) a layer on the substrate, the layer having had a contaminant and which contaminant has been reduced by the process of: 
 i) initiating a plasma in a chamber with a reducing agent; and  
 ii) exposing at least a portion of the layer having the contaminant to the reducing agent.  
   
     
     
         20 . The substrate of    claim 19   , wherein the reducing agent comprises ammonia.