Endpoint for electrochemical processing

Abstract

A method and apparatus for electrochemically processing a substrate is provided. In one embodiment, a method for electrochemically processing a substrate includes the steps of establishing an electrically-conductive path through an electrolyte between an exposed layer of barrier material on the substrate and an electrode, electrochemically removing a portion of the exposed layer during a first electrochemical processing step in a barrier processing station, detecting an endpoint of the first electrochemical processing step at or just prior to breakthrough of the exposed layer of barrier material, electrochemically processing the exposed layer of barrier material in a second electrochemical processing step in the barrier processing station, and detecting an endpoint of the second electrochemical processing step.

1 . A method for electroprocessing a substrate, comprising: 
 establishing an electrically-conductive path through an electrolyte between an exposed layer of barrier material on the substrate and an electrode;    electrochemically removing a portion of the exposed layer during a first electrochemical processing step in a barrier processing station;    detecting an endpoint of the first electrochemical processing step at or just prior to breakthrough of the exposed layer of barrier material;    electrochemically processing the exposed layer of barrier material in a second electrochemical processing step in the barrier processing station; and    detecting an endpoint of the second electrochemical processing step.    
     
     
         2 . The method of  claim 1 , wherein the step of establishing a conductive path further comprises: 
 flowing electrolyte from below the electrode and through a processing pad assembly into contact with the substrate.    
     
     
         3 . The method of  claim 1  comprising: 
 contacting the barrier material on the substrate with a processing pad assembly; and    moving the substrate relative to the pad assembly in a polishing motion;    
     
     
         4 . The method of  claim 1 , wherein the second electrochemical processing step further comprises: 
 detecting a first endpoint;    processing the substrate at a slower rate; and    detecting a second endpoint indicative of residual barrier material being cleared from the substrate.    
     
     
         5 . The method of  claim 4 , wherein the second electrochemical processing step further comprises: 
 overpolishing the substrate after detection of the second endpoint.    
     
     
         6 . The method of  claim 4 , wherein the step of detecting the first endpoint further comprises: 
 detecting a first discontinuity in a potential difference between the substrate and the electrode.    
     
     
         7 . The method of  claim 6 , wherein the step of detecting the second endpoint further comprises: 
 detecting a second discontinuity in a potential difference between the substrate and the electrode.    
     
     
         8 . The method of  claim 4 , wherein the step of detecting the first endpoint further comprises: 
 detecting a first discontinuity in a current passing between the substrate and the electrode.    
     
     
         9 . The method of  claim 8 , wherein the step of detecting the second endpoint further comprises: 
 detecting a second discontinuity in the current passing between the substrate and the electrode.    
     
     
         10 . The method of  claim 5 , wherein the over polish step has a duration of 15 to 35 seconds.  
     
     
         11 . The method of  claim 1 , wherein the barrier processing station is disposed within an enclosure of a processing system.  
     
     
         12 . The method of  claim 11  further comprising: 
 removing, within the processing system, a conductive layer disposed over the barrier layer.    
     
     
         13 . The method of  claim 12  further comprising: 
 electrochemically processing the conductive layer.    
     
     
         14 . The method of  claim 13  further comprising: 
 transferring the substrate between a first electrochemical processing station to the barrier processing station.    
     
     
         15 . The method of  claim 1  further comprising: 
 determining a remaining thickness of the barrier layer from a change in current between the substrate and the electrode.    
     
     
         16 . A method of electrochemically processing a substrate having an exposed conductive layer and an underlying barrier layer, comprising: 
 establishing an electrically-conductive path through an electrolyte between the exposed layer of conductive material on the substrate and an electrode;    electrochemically removing a portion of the exposed layer during a first electrochemical processing step in a first processing station;    detecting an endpoint of the first electrochemical processing step at or just prior to breakthrough of the exposed layer of conductive material;    electrochemically processing the exposed layer of conductive material in a second electrochemical processing step;    detecting an endpoint of the second electrochemical processing step;    transferring the substrate to a barrier removal station; and    electrochemically processing the barrier layer.    
     
     
         17 . The method of  claim 16 , wherein the second electrochemical processing step is performed in the first processing station.  
     
     
         18 . The method of  claim 16  further comprising: 
 transferring the substrate to a second processing station where the second electrochemical processing step is performed.    
     
     
         19 . The method of  claim 16 , wherein the step of establishing a conductive path further comprises: 
 flowing electrolyte from below the electrode and through a processing pad assembly into contact with the substrate.    
     
     
         20 . The method of  claim 17 , wherein the second electrochemical processing step further comprises: 
 detecting a first endpoint;    processing the substrate at a slower rate; and    detecting a second endpoint indicative of residual conductive material being cleared from the substrate.    
     
     
         21 . The method of  claim 20 , wherein the second electrochemical processing step further comprises: 
 overpolishing the substrate after detection of the second endpoint.    
     
     
         22 . The method of  claim 20 , wherein the step of detecting the first endpoint further comprises: 
 detecting a first discontinuity in a potential difference between the substrate and the electrode.    
     
     
         23 . The method of  claim 22 , wherein the step of detecting the second endpoint further comprises: 
 detecting a second discontinuity in a potential difference between the substrate and the electrode.    
     
     
         24 . The method of  claim 20 , wherein the step of detecting the first endpoint further comprises: 
 detecting a first discontinuity in a current passing between the substrate and the electrode.    
     
     
         25 . The method of  claim 24 , wherein the step of detecting the second endpoint further comprises: 
 detecting a second discontinuity in the current passing between the substrate and the electrode.    
     
     
         26 . The method of  claim 21 , wherein the over polish step has a duration of 15 to 35 seconds.  
     
     
         27 . The method of  claim 16 , wherein the barrier electrochemical processing step further comprises: 
 detecting a first endpoint;    processing the substrate at a slower rate; and    detecting a second endpoint indicative of barrier material being cleared from the substrate.    
     
     
         28 . The method of  claim 27 , wherein the barrier electrochemical processing step further comprises: 
 overpolishing the substrate after detection of the second endpoint.    
     
     
         29 . The method of  claim 28 , wherein the step of detecting the first endpoint further comprises: 
 detecting a first discontinuity in a potential difference between the substrate and the electrode.    
     
     
         30 . The method of  claim 27 , wherein the step of detecting the second endpoint further comprises: 
 detecting a second discontinuity in a potential difference between the substrate and the electrode.    
     
     
         31 . The method of  claim 27 , wherein the step of detecting the first endpoint further comprises: 
 detecting a first discontinuity in a current passing between the substrate and the electrode.    
     
     
         32 . The method of  claim 27 , wherein the step of detecting the second endpoint further comprises: 
 detecting a second discontinuity in the current passing between the substrate and the electrode.    
     
     
         33 . The method of  claim 28 , wherein the over polish step has a duration of 15 to 35 seconds.  
     
     
         34 . The method of  claim 16  comprising: 
 contacting an exposed layer of conductive material on the substrate with a polishing pad; and    moving the substrate relative to the pad in a polishing motion.    
     
     
         35 . The method of  claim 15  further comprising: 
 determining a thickness remaining of the conductive material from a change in current.    
     
     
         36 . A method of electrochemically processing a substrate having an exposed conductive layer and an underlying barrier layer, comprising: 
 disposing the substrate on a processing pad assembly in a first processing station of a processing system;    establishing an electrically-conductive path through an electrolyte between the exposed layer of conductive material on the substrate and an electrode;    providing a polishing motion between the processing pad assembly and the substrate in contact therewith;    electrochemically removing a portion of the exposed layer during a first electrochemical processing step in the first processing station;    detecting an endpoint of the first electrochemical processing step at or just prior to breakthrough of the exposed layer of conductive material;    electrochemically processing the exposed layer of conductive material in a second electrochemical processing step;    detecting an endpoint of the second electrochemical processing step;    transferring the substrate to a barrier removal station;    establishing an electrically-conductive path through an electrolyte between the barrier layer and an electrode disposed in the barrier removal station;    electrochemically removing a portion of the barrier layer during a first electrochemical barrier processing step in a barrier processing station;    detecting an endpoint of the first electrochemical barrier processing step at or just prior to breakthrough of barrier material;    electrochemically processing the barrier material in a second electrochemical barrier processing step in the barrier processing station; and    detecting an endpoint of the second electrochemical processing step.    
     
     
         37 . The method of  claim 36 , wherein the step of detecting at least two of endpoints of the barrier and conductive material processing steps further comprises: 
 detecting discontinuities in a potential difference between the substrate and the electrode.    
     
     
         38 . The method of  claim 36 , wherein the step of detecting at least two of endpoints of the barrier and copper processing steps further comprises: 
 detecting discontinuities in current measured between the substrate and the electrode.    
     
     
         39 . The method of  claim 36  further comprising: 
 determining a thickness remaining of the conductive material from a change in current.