Tuning of polishing process in multi-carrier head per platen polishing station

Abstract

An apparatus and method for simulating a substrate being polished in a multiple carrier head per platen station when no substrate is provided in one or more of the multiple carrier heads is described. In one embodiment, a method for processing a substrate includes providing a single substrate to a polishing station adapted to process a plurality of substrates on a single polishing pad using at least a first carrier head and a second carrier head, retaining the single substrate in the first carrier head while the second carrier head remains substrate-free, urging the first carrier head and the second carrier head toward a polishing surface of the polishing pad; and providing relative movement between the polishing pad and the first carrier head.

1 . A method for tuning a polishing process on a substrate in a processing station having at least a first carrier head and a second carrier head adapted to retain and process a substrate using a common polishing pad, the method comprising:
 retaining a single substrate in a first retaining ring disposed on the first carrier head while the second carrier head remains empty;   urging the first carrier head and the single substrate toward a polishing surface of the polishing pad while bringing the second retaining ring disposed on the second carrier head into contact with the polishing surface, the second carrier head remaining empty;   providing relative motion between the single substrate and the polishing pad; and   varying at least one of a pressure of the second retaining ring against the polishing pad and a rotational speed of the second carrier head relative to the polishing pad.   
     
     
         2 . The method of  claim 1 , further comprising:
 urging the first retaining ring disposed on the first carrier head toward the polishing surface of the polishing pad at a first pressure.   
     
     
         3 . The method of  claim 2 , wherein the second retaining ring disposed on the second carrier head is urged toward the polishing surface at a second pressure that is less than the first pressure. 
     
     
         4 . The method of  claim 2 , wherein the second retaining ring disposed on the second carrier head is urged toward the polishing surface at a second pressure, the first pressure and the second pressure being substantially equal. 
     
     
         5 . The method of  claim 1 , wherein the first carrier head is rotated at a first velocity relative to the polishing pad and the second carrier head is rotated at a second velocity relative to the polishing pad that is less than the first velocity. 
     
     
         6 . The method of  claim 1 , wherein the first carrier head is rotated at a first velocity relative to the polishing pad and the second carrier head is rotated at a second velocity relative to the polishing pad that is substantially equal to the first velocity. 
     
     
         7 . The method of  claim 1 , wherein the first retaining ring is urged toward the polishing surface of the polishing pad at a first pressure and the second retaining ring disposed on the second carrier head is urged toward the polishing surface of the polishing pad at a second pressure. 
     
     
         8 . The method of  claim 7 , wherein the second pressure is less than the first pressure. 
     
     
         9 . The method of  claim 7 , wherein the second pressure and the first pressure is substantially equal. 
     
     
         10 . A method for tuning a polishing process on at least a first substrate in a polishing station adapted to process at least one substrate greater than the first substrate on a common polishing pad, the method comprising:
 retaining the first substrate in a first retaining ring disposed on at least one used carrier head;   urging the first retaining ring disposed on the at least one used carrier head and a second retaining ring disposed on at least one empty carrier head toward a polishing surface of the polishing pad, the at least one empty carrier head remaining substrate-free; and   providing relative movement between the polishing pad and the at least one used carrier head.   
     
     
         11 . The method of  claim 10 , wherein the first retaining ring is urged toward the polishing pad at a first pressure and the second retaining ring is urged toward the polishing surface at a second pressure that is less than the first pressure. 
     
     
         12 . The method of  claim 10 , wherein the first retaining ring is urged toward the polishing pad at a first pressure and the second retaining ring is urged toward the polishing surface at a second pressure, the first pressure and the second pressure being substantially equal. 
     
     
         13 . The method of  claim 10 , further comprising:
 providing relative motion between the empty carrier head and the polishing pad.   
     
     
         14 . The method of  claim 13 , wherein the used carrier head is rotated at a first velocity and the empty carrier head is rotated at a second velocity that is less than the first velocity. 
     
     
         15 . The method of  claim 13 , wherein the first retaining ring is urged toward the polishing pad at a first pressure and the second retaining ring is urged toward the polishing surface at a second pressure that is less than the first pressure. 
     
     
         16 . The method of  claim 13 , wherein the first retaining ring is urged toward the polishing pad at a first pressure and the second retaining ring is urged toward the polishing surface at a second pressure, the first pressure and the second pressure being substantially equal. 
     
     
         17 . A method for processing a substrate, comprising:
 receiving at least one substrate in a polishing station adapted to process a number of substrates greater than the at least one substrate on a common polishing pad using at least a first carrier head and a second carrier head;   positioning the at least one substrate in a retaining ring disposed on the first carrier head while the second carrier head remains empty;   urging the first carrier head and the second carrier head toward a polishing surface of the polishing pad; and   providing relative movement between the polishing pad and the first carrier head.   
     
     
         18 . The method of  claim 17 , wherein the first retaining ring is urged toward the polishing pad at a first pressure and the second retaining ring is urged toward the polishing surface at a second pressure that is less than the first pressure. 
     
     
         19 . The method of  claim 17 , wherein the first retaining ring is urged toward the polishing pad at a first pressure and the second retaining ring is urged toward the polishing surface at a second pressure, the first pressure and the second pressure being substantially equal. 
     
     
         20 . The method of  claim 17 , wherein the first carrier head is rotated at a first velocity and the second carrier head is rotated at a second velocity that is less than the first velocity. 
     
     
         21 . The method of  claim 17 , wherein the first carrier head is rotated at a first velocity and the second carrier head is rotated at a second velocity that is substantially equal to the first velocity.