Polishing apparatus having optical monitoring of substrates for uniformity control and separate endpoint system

Abstract

A computer-implemented method of generating reference spectra includes polishing a first substrate in a polishing apparatus having a rotatable platen, measuring a sequence of spectra from the substrate during polishing with an in-situ monitoring system, associating each spectrum in the sequence of spectra with a index value equal to a number of platen rotations at which the each spectrum was measured, and storing the sequence of spectra as reference spectra.

What is claimed is: 
     
         1 - 15 . (canceled) 
     
     
         16 . A computer-implemented method of controlling polishing of a substrate, comprising:
 polishing a substrate;   monitoring a plurality of zones of a substrate during polishing with an in-situ spectrographic monitoring system;   monitoring the substrate during polishing with an endpoint detection system other than the in-situ spectrographic monitoring system, the monitoring including generating measurements from the endpoint detection system;   determining a projected endpoint time from a plurality of spectra collected by the in-situ spectrographic monitoring system and without using the measurements from the endpoint detection system;   adjusting a polishing parameter for at least one zone on the substrate based on data from the in-situ spectrographic monitoring system and without using the measurements from the endpoint detection system to adjust the polishing rate of the at least one zone such that the at least one zone has closer to a target thickness at the projected endpoint time than without such adjustment;   detecting a polishing endpoint with the endpoint detection system and without using the data from the in-situ spectrographic monitoring system; and   halting polishing when the endpoint detection system detects the polishing endpoint.   
     
     
         17 . The method of  claim 16 , wherein the endpoint detection system comprises one or more of a motor torque monitoring system, an eddy current monitoring system, a friction monitoring system, or a monochromatic optical monitoring system. 
     
     
         18 . The method of  claim 16 , further comprising:
 measuring a first sequence of spectra from a first zone of the substrate during polishing with the in-situ spectrographic monitoring system;   for each measured spectrum in the first sequence of spectra, finding a best matching reference spectrum from a first plurality of reference spectra to generate a first sequence of best matching spectra;   for each best matching reference spectrum in the first sequence of best matching spectra, determining an index value of the best matching reference spectrum to generate a first sequence of index values;   measuring a second sequence of measured spectra from a second zone of the substrate during polishing with the in-situ spectrographic monitoring system;   for each measured spectrum in the second sequence of spectra, finding a best matching reference spectrum from a second plurality of reference spectra to generate a second sequence of best matching spectra; and   for each best matching reference spectrum in the second sequence of best matching spectra, determining an index value of the best matching reference spectrum to generate a second sequence of index values.   
     
     
         19 . The method of  claim 18 , further comprising:
 determining a projected time at which the first zone of the substrate will reach a target index value based on the first sequence of index values; and   adjusting a polishing parameter for the second zone such that the second zone has closer to the target index at the projected time than without such adjustment.   
     
     
         20 . A computer program product tangibly encoded on a non-transitory machine-readable storage media, comprising instructions for causing a processor to:
 receive a plurality of spectra for plurality of zones of a substrate collected by an in-situ spectrographic monitoring system during polishing of the substrate in a polishing system;   receive measurements of the substrate during polishing from an endpoint detection system other than the in-situ spectrographic monitoring;   determine a projected endpoint time from a plurality of spectra collected by the in-situ spectrographic monitoring system and without using the measurements from the endpoint detection system;   adjust a polishing parameter for at least one zone on the substrate based on data from the in-situ spectrographic monitoring system and without using the measurements from the endpoint detection system to adjust the polishing rate of the at least one zone such that the at least one zone has closer to a target thickness at the projected endpoint time than without such adjustment;   detect a polishing endpoint based on measurements from the endpoint detection system and without using the data from the in-situ spectrographic monitoring system; and   cause the polishing system to halt polishing when the endpoint detection system detects the polishing endpoint.   
     
     
         21 . The computer program product of  claim 20 , further comprising instructions to:
 receive measurements of a first sequence of spectra from a first zone of the substrate during polishing from the in-situ spectrographic monitoring system;   for each measured spectrum in the first sequence of spectra, find a best matching reference spectrum from a first plurality of reference spectra to generate a first sequence of best matching spectra;   for each best matching reference spectrum in the first sequence of best matching spectra, determine an index value of the best matching reference spectrum to generate a first sequence of index values;   receive measurements of a second sequence of measured spectra from a second zone of the substrate during polishing from the in-situ spectrographic monitoring system;   for each measured spectrum in the second sequence of spectra, find a best matching reference spectrum from a second plurality of reference spectra to generate a second sequence of best matching spectra; and   for each best matching reference spectrum in the second sequence of best matching spectra, determine an index value of the best matching reference spectrum to generate a second sequence of index values.   
     
     
         22 . The computer program product of  claim 21 , further comprising instructions to:
 determine a projected time at which the first zone of the substrate will reach a target index value based on the first sequence of index values; and   adjust a polishing parameter for the second zone such that the second zone has closer to the target index at the projected time than without such adjustment.   
     
     
         23 . A polishing apparatus, comprising:
 a support to hold a polishing pad;   a carrier head to hold a substrate in contact with the polishing pad;   a motor to generate relative motion between the substrate and the polishing pad;   an in-situ spectrographic monitoring system to collect a plurality of spectra for plurality of zones of the substrate during polishing of the substrate;   an endpoint detection system other than the in-situ spectrographic monitoring system; and   a controller configured to
 receive the plurality of spectra from the in-situ spectrographic monitoring system during polishing of the substrate, 
 receive measurements of the substrate during polishing from the endpoint detection system, 
 determine a projected endpoint time from the plurality of spectra collected by the in-situ spectrographic monitoring system and without using the measurements from the endpoint detection system, 
 adjust a polishing parameter for at least one zone on the substrate based on data from the in-situ spectrographic monitoring system and without using the measurements from the endpoint detection system to adjust the polishing rate of the at least one zone such that the at least one zone has closer to a target thickness at the projected endpoint time than without such adjustment; 
 detect a polishing endpoint based on measurements from the endpoint detection system and without using the data from the in-situ spectrographic monitoring system; and 
 cause the polishing system to halt polishing when the endpoint detection system detects the polishing endpoint. 
   
     
     
         24 . The polishing apparatus of  claim 23 , wherein the endpoint detection system comprises one or more of a motor torque monitoring system, an eddy current monitoring system, a friction monitoring system, or a monochromatic optical monitoring system. 
     
     
         25 . The polishing apparatus of  claim 23 , wherein the support comprises a rotatable platen. 
     
     
         26 . The polishing apparatus of  claim 25 , wherein the platen comprises a recess, and wherein a sensor of the in-situ spectrographic monitoring system and a sensor of the endpoint detection system are in the same recess. 
     
     
         27 . The polishing apparatus of  claim 25 , wherein the platen comprises a first recess and a separate second recess, and wherein a sensor of the in-situ spectrographic monitoring system is in the first recess and a sensor of the endpoint detection system is in the second recess. 
     
     
         28 . The polishing apparatus of  claim 25 , wherein a sensor of the endpoint detection system has the same radial distance from an axis of rotation of the platen as a sensor of the in-situ spectrographic monitoring system. 
     
     
         29 . The polishing apparatus of  claim 22 , wherein the controller is configured to:
 receive measurements of a first sequence of spectra from a first zone of the substrate during polishing from the in-situ spectrographic monitoring system;   for each measured spectrum in the first sequence of spectra, find a best matching reference spectrum from a first plurality of reference spectra to generate a first sequence of best matching spectra;   for each best matching reference spectrum in the first sequence of best matching spectra, determine an index value of the best matching reference spectrum to generate a first sequence of index values;   receive measurements of a second sequence of measured spectra from a second zone of the substrate during polishing from the in-situ spectrographic monitoring system;   for each measured spectrum in the second sequence of spectra, find a best matching reference spectrum from a second plurality of reference spectra to generate a second sequence of best matching spectra; and   for each best matching reference spectrum in the second sequence of best matching spectra, determine an index value of the best matching reference spectrum to generate a second sequence of index values.   
     
     
         30 . The polishing apparatus of  claim 29 , wherein the controller is configured to:
 determine a projected time at which the first zone of the substrate will reach a target index value based on the first sequence of index values; and   adjust a polishing parameter for the second zone such that the second zone has closer to the target index at the projected time than without such adjustment.