Method for stabilized polishing process

Abstract

A method for electrochemically processing a substrate is provided. In one embodiment, a method for electrochemically processing a substrate includes processing a substrate using a multi-step routine that includes a first processing period performed using a varying voltage to achieve a target removal current followed by a second processing period performed using a constant voltage.

1 . A method for electroprocessing a substrate, comprising: 
 establishing an electrically-conductive path through an electrolyte between an exposed layer of material on the substrate and an electrode;    electrochemically removing a first portion of the exposed layer while adjusting voltage to achieve a target removal current; and    electrochemically removing a second portion of the exposed layer with a constant voltage corresponding to the target removal current.    
   
   
       2 . The method of  claim 1 , further comprising: 
 pressing the exposed layer of material against a partially conductive surface of a polishing pad.    
   
   
       3 . The method of  claim 2 , wherein the pressing further comprises: 
 pressing the substrate against the polishing pad with a pressure of less than 2 pounds per square inch.    
   
   
       4 . The method of  claim 1 , wherein the target removal current is determined before removing the first portion of the exposed layer.  
   
   
       5 . The method of  claim 1 , wherein the target removal current is determined by an incoming thickness profile of the substrate using historical data and/or an algorithm based on the incoming thickness profile.  
   
   
       6 . The method of  claim 1 , further comprising: 
 adjusting a first processing voltage across a first processing zone of the electrode while removing the first portion; and    adjusting a second processing voltage across a second processing zone of the electrode while removing the second portion.    
   
   
       7 . The method of  claim 1 , further comprising: 
 fixing the voltage to provide the constant voltage corresponding to the target removal current after the adjusted voltage has reached a near stabilized state.    
   
   
       8 . A method for processing a substrate in an electrochemical mechanical planarizing system, comprising: 
 processing a first substrate on a polishing pad for a first processing period performed to achieve a target removal current; and    processing the first substrate on the polishing pad for a second processing period performed using a constant voltage based on the target removal current.    
   
   
       9 . The method of  claim 8 , wherein processing the first substrate for the first processing period further comprises: 
 adjusting a processing voltage during the first processing period.    
   
   
       10 . The method of  claim 8 , wherein processing the first substrate for the first processing period further comprises: 
 adjusting a first processing voltage across a first processing zone during the first processing period; and    adjusting a second processing voltage across a second processing zone during the first processing period.    
   
   
       11 . The method of  claim 10 , wherein adjusting the first and second processing voltages further comprises: 
 applying different voltages to an outer portion of the first substrate relative to an inner portion of the first substrate.    
   
   
       12 . The method of  claim 8 , wherein processing the first substrate for the first and second period includes establishing an electrochemical circuit between an exposed layer of conductive material on the first substrate in contact with the polishing pad, and an electrode disposed in the polishing pad through an electrolyte.  
   
   
       13 . The method of  claim 8 , wherein processing the first substrate for the first and second period includes establishing an electrochemical circuit between an exposed layer of conductive material on the first substrate and an electrode disposed in the polishing pad in the presence of an electrolyte, wherein an upper surface of the pad includes a partially conductive surface to bias the exposed layer of conductive material.  
   
   
       14 . The method of  claim 8  further comprising: 
 processing a second substrate for a first processing period performed to achieve a second target removal current; and    processing the second substrate for a second processing period performed using a second constant voltage based on the second target removal current.    
   
   
       15 . The method of  claim 14 , wherein the processing the second substrate for the second processing period further comprises: 
 applying the second constant voltage greater than the first constant voltage.    
   
   
       16 . The method of  claim 14  further comprising: 
 conditioning a processing surface of the polishing pad; and    applying the second constant voltage less than the first constant voltage.    
   
   
       17 . The method of  claim 8  further comprising: 
 removing a conductive material from the first substrate in a bulk processing step on a processing tool; and    processing the conductive material on the first substrate for the first and second period on the processing tool in-situ in a residual processing step.    
   
   
       18 . The method of  claim 17 , wherein processing the conductive material for the first and second periods further comprises: 
 processing the first substrate on a single polishing pad disposed on the polishing tool.    
   
   
       19 . The method of  claim 17 , wherein processing the conductive material for the first and second periods further comprises: 
 processing the first substrate on two polishing pads disposed on the polishing tool.    
   
   
       20 . The method of  claim 17 , wherein processing the conductive material for the first and second periods further comprises: 
 processing the first substrate on a fully conductive processing pad.    
   
   
       21 . The method of  claim 20 , wherein processing the first substrate for the first and second period includes establishing an electrochemical circuit between an exposed layer of conductive material on the first substrate in contact with the polishing pad, and an electrode disposed in the polishing pad through an electrolyte.  
   
   
       22 . The method of  claim 8 , wherein the second processing period is much greater than the first processing period.  
   
   
       23 . The method of  claim 8 , further comprising: 
 fixing the voltage to provide the constant voltage based on the target removal current after the adjusted voltage has reached a near stabilized state.    
   
   
       24 . The method of  claim 8 , further comprising: 
 adjusting a first processing voltage across a first processing zone of an electrode disposed in the polishing pad while removing the first portion; and    adjusting a second processing voltage across a second processing zone of the electrode while removing the second portion.