Method and apparatus for cleaning integrated circuit bonding pads

Abstract

A method for cleaning bonding pads on a semiconductor device, as disclosed herein, includes treating the bonding pads with a CF 4 and water vapor combination. In the process, the water vapor breaks up and the hydrogen from the water vapor couples to fluorine residue on the bonding pad surface creating a volatile HF vapor. In addition, fluorine from the CF 4 exchanges with the titanium in the metallic polymer residue making the polymer more soluble for the organic strip operation which follows. Next, the resist is ashed and then an organic resist stripper is applied to the bonding pad area, thereby creating a clean bonding pad surface. Thereafter, a reliable bond wire connection can be made to the bonding pad.

What is claimed is:  
     
         1 . A method for cleaning integrated circuit contacts comprising: 
 treating an integrated circuit having at least one metal contact aligned with an opening provided through a passivation layer and a resist layer with CF 4  and water vapor to volatize fluorine from said metal contact and to soften metallic polymers adhering to sidewalls of said opening;    ashing said integrated circuit to substantially remove said resist layer; and    stripping said integrated circuit in a liquid solvent to substantially remove contaminants including said softened metallic polymers.    
     
     
         2 . A method for cleaning integrated circuit contacts as recited in  claim 1  wherein said passivation layer is a Nitride layer.  
     
     
         3 . A method for cleaning integrated circuit contacts as recited in  claim 2  wherein an oxide layer is provided between said passivation layer and said contact, and wherein said opening is further provided through said oxide layer.  
     
     
         4 . A method for cleaning integrated circuit contacts as recited in  claim 3  wherein a barrier layer is provided between said oxide layer and said contact, and wherein said opening is further provided through said barrier layer.  
     
     
         5 . A method for cleaning integrated circuit contacts as recited in  claim 4  wherein said contact is an AlCu alloy, said nitride layer is SiN, said oxide layer is SiO 2 , and said barrier layer is selected from the group consisting essentially of TiW and TiN.  
     
     
         6 . A method for cleaning integrated circuit contacts as recited in  claim 1  wherein said treating an integrated circuit is accomplished within an asher apparatus.  
     
     
         7 . A method for cleaning integrated circuit contacts as recited in  claim 6  wherein said asher apparatus is a plasma asher apparatus.  
     
     
         8 . A method for cleaning integrated circuit contacts as recited in  claim 6  wherein said asher apparatus is a microwave asher apparatus.  
     
     
         9 . A method for cleaning integrated circuit contacts as recited in  claim 6  wherein said CF 4  and water vapor are ionized by said asher apparatus.  
     
     
         10 . A method for cleaning integrated circuit contacts as recited in  claim 9  wherein hydrogen from said ionized water combines with fluorine from said metal contact to form a volatile HF vapor.  
     
     
         11 . A method for cleaning integrated circuit contacts as recited in  claim 9  wherein fluorine from said ionized CF 4 exchanges with metal from said metallic polymers to soften said polymers.  
     
     
         12 . A method for cleaning integrated circuit contacts as recited in  claim 6  wherein said integrated circuit sits on a heated paddle at a setpoint of approximately 200C.  
     
     
         13 . An integrated circuit with clean contacts made by the method of  claim 1 .  
     
     
         14 . A system for cleaning integrated circuit contacts comprising: 
 an asher apparatus capable of treating an integrated circuit having at least one metal contact aligned with an opening provided through a passivation layer and a resist layer with CF 4  and water vapor to volatize fluorine from said metal contact and to soften metallic polymers adhering to sidewalls of said opening;    an asher apparatus capable of ashing said integrated circuit to substantially remove said resist layer; and    an organic resist stripper capable of stripping said integrated circuit in a liquid solvent to substantially remove contaminants including said softened metallic polymers.    
     
     
         15 . A system for cleaning integrated circuit contacts as recited in  claim 14  wherein said CF 4  and water vapor are ionized by said asher apparatus.  
     
     
         16 . A system for cleaning integrated circuit contacts as recited in  claim 14  wherein hydrogen from said ionized water combines with fluorine from said metal contact to form a volatile HF vapor.  
     
     
         17 . A system for cleaning integrated circuit contacts as recited in  claim 14  wherein fluorine from said ionized CF 4  exchanges with metal from said metallic polymers to soften said polymers.  
     
     
         18 . A system for cleaning integrated circuit contacts as recited in  claim 14  wherein said integrated circuit sits on a heated paddle at a setpoint of approximately 200C.  
     
     
         19 . A system as recited in  claim 14  further comprising back end processors for finishing and packaging said integrated circuit.