Method of detecting polishing endpoint, and program for detecting polishing endpoint

Abstract

A polishing endpoint detecting method capable of accurately detecting a polishing endpoint of a substrate is disclosed. The polishing endpoint detecting method includes: polishing a substrate W; creating a film-thickness profile of the substrate by used of a film-thickness sensor 7 mounted to a polishing table 2; dividing the film-thickness profile into a plurality of measurement zones and selecting a monitoring zone from the plurality of measurement zones for determining a polishing endpoint of the substrate; determining whether or not the monitoring zone is changed to another measurement zone based on changes in the film-thickness profile obtained from start to end of polishing of the substrate; and determining a polishing endpoint of the substrate based on the signals in the monitoring zone.

What is claimed is: 
     
         1 . A polishing endpoint detecting method, comprising:
 polishing a substrate by rotating a polishing table which supports a polishing pad and pressing the substrate against a polishing surface of the polishing pad by use of a polishing head;   sequentially acquiring signals, corresponding to the film thickness of the substrate, at a plurality of measurement points in the substrate when a film-thickness sensor mounted to the polishing table moves across the substrate, thereby creating a film-thickness profile of the substrate each time the polishing table is rotated a predetermined number of times;   dividing the film-thickness profile into a plurality of measurement zones and selecting a monitoring zone from the plurality of measurement zones for determining a polishing endpoint of the substrate;   determining whether or not the monitoring zone is changed to another measurement zone based on changes in the film-thickness profile obtained from start to end of polishing of the substrate; and   determining a polishing endpoint of the substrate based on the signals in the monitoring zone.   
     
     
         2 . The polishing endpoint detecting method according to  claim 1 , wherein selecting the monitoring zone is calculating differences in film thickness between each of the measurement zones and selecting the measurement zone with the smallest amount of remaining film as the monitoring zone when any of the differences exceeds a predetermined threshold value. 
     
     
         3 . The polishing endpoint detecting method according to  claim 1 , wherein selecting the monitoring zone is calculating differences in film thickness between each of the measurement zones and selecting the measurement zone with the largest amount of remaining film as the monitoring zone when any of the differences exceeds a predetermined threshold value. 
     
     
         4 . The polishing endpoint detecting method according to  claim 1 , further comprising:
 constructing a learned model that is constructed to output the monitoring zone to be changed when state variables, including at least the film-thickness profile, are input,   wherein selecting the monitoring zone is performed based on an output when the created film-thickness profile is input to the learned model.   
     
     
         5 . A polishing endpoint detecting method, comprising:
 polishing a substrate by rotating a polishing table which supports a polishing pad and pressing the substrate against a polishing surface of the polishing pad by use of a polishing head;   sequentially acquiring signals, corresponding to the film thickness of the substrate, at a plurality of measurement points in the substrate when a film-thickness sensor mounted to the polishing table moves across the substrate, thereby creating a film-thickness profile of the substrate each time the polishing table is rotated a predetermined number of times;   dividing the film-thickness profile into a plurality of measurement zones;   determining whether or not ranges of each of the measurement zones are changed based on changes in the film-thickness profile obtained from start to end of polishing of the substrate; and   determining a polishing endpoint of the substrate based on the signals in the plurality of the measurement zones.   
     
     
         6 . The polishing endpoint detecting method according to  claim 5 , wherein changing the ranges of each of the measurement zones is obtaining an inflection point of the film-thickness profile between adjacent measurement zones, and shifting a border of the adjacent measurement zones to the inflection point. 
     
     
         7 . The polishing endpoint detecting method according to  claim 5 , wherein changing the ranges of each of the measurement zones is calculating differences between measurement values of film thickness at adjacent measurement points, and shifting a border of adjacent measurement zones between two excess measurement points when the two excess measurement points appear where the difference exceeds a threshold value. 
     
     
         8 . The polishing endpoint detecting method according to  claim 5 , wherein changing the ranges of each of the measurement zones is calculating variations of a plurality of measurement values of the film thickness for each of the measurement zones, and shifting a border between adjacent measurement zones such that the variations are less than or equal to an allowable value. 
     
     
         9 . The polishing endpoint detecting method according to  claim 5 , further comprising constructing a learned model that is constructed so as to output the ranges of measurement zones to be changed when state variables, including at least the film-thickness profile, are inputted,
 wherein changing the ranges of each of the measurement zones is performed based on the output when the created film-thickness profiles are input to the learned model.   
     
     
         10 . A program for causing a computer to execute:
 polishing a substrate by rotating a polishing table which supports a polishing pad and pressing the substrate against a polishing surface of the polishing pad by use of a polishing head;   sequentially acquiring signals, corresponding to the film thickness of the substrate, at a plurality of measurement points in the substrate when a film-thickness sensor mounted to the polishing table moves across the substrate, thereby creating a film-thickness profile of the substrate each time the polishing table is rotated a predetermined number of times;   dividing the film-thickness profile into a plurality of measurement zones and selecting a monitoring zone from the plurality of measurement zones for determining a polishing endpoint of the substrate;   determining whether or not the monitoring zone is changed to another measurement zone based on changes in the film-thickness profile obtained from start to end of polishing of the substrate; and   determining a polishing endpoint of the substrate based on the signals in the monitoring zone.   
     
     
         11 . The program according to  claim 10 , wherein selecting the monitoring zone is calculating differences in film thickness between each of the measurement zones and selecting the measurement zone with the smallest amount of remaining film as the monitoring zone when any of the differences exceeds a predetermined threshold value. 
     
     
         12 . The program according to  claim 10 , wherein selecting the monitoring zone is calculating differences in film thickness between each of the measurement zones and selecting the measurement zone with the largest amount of remaining film as the monitoring zone when any of the differences exceeds a predetermined threshold value. 
     
     
         13 . The program according to  claim 10 , wherein selecting the monitoring zone is performed based on an output when the created film-thickness profile is input to a learned model, and
 the learned model is constructed so as to output the monitoring zone to be changed when state variables, including at least the film-thickness profile, are input.   
     
     
         14 . A program for causing a computer to execute:
 polishing a substrate by rotating a polishing table which supports a polishing pad and pressing the substrate against a polishing surface of the polishing pad by use of a polishing head;   sequentially acquiring signals, corresponding to the film thickness of the substrate, at a plurality of measurement points in the substrate when a film-thickness sensor mounted to the polishing table moves across the substrate, thereby creating a film-thickness profile of the substrate each time the polishing table is rotated a predetermined number of times;   dividing the film-thickness profile into a plurality of measurement zones;   determining whether or not ranges of each of the measurement zones are changed based on changes in the film-thickness profile obtained from start to end of polishing of the substrate; and   determining a polishing endpoint of the substrate based on the signals in the plurality of the measurement zones.   
     
     
         15 . The program according to  claim 14 , wherein changing the ranges of each of the measurement zones is obtaining an inflection point of the film-thickness profile between adjacent measurement zones, and shifting a border of the adjacent measurement zones to the inflection point. 
     
     
         16 . The program according to  claim 14 , wherein changing the ranges of each of the measurement zones is calculating differences between measurement values of film thickness at adjacent measurement points, and shifting a border of adjacent measurement zones between two excess measurement points when the two excess measurement points appear where the difference exceeds a threshold value. 
     
     
         17 . The program according to  claim 14 , wherein changing the ranges of each of the measurement zones is calculating variations of a plurality of measurement values of the film thickness for each of the measurement zones, and shifting a border between adjacent measurement zones such that the variations are less than or equal to an allowable value. 
     
     
         18 . The program according to  claim 14 , wherein changing the ranges of each of the measurement zones is performed based on an output when the created film-thickness profiles are input to a learned model, and
 the learned model is constructed so as to output the ranges of measurement zones to be changed when state variables, including at least the film-thickness profile, are inputted.