Polishing method and polishing device

Abstract

A polishing method and a polishing device are provided. The polishing method includes: outputting a film thickness monitoring signal in accordance to a film thickness of a substrate by a sensor during polishing of the substrate; determining, based on the film thickness monitoring signal in each of a first region and a second region on the substrate, a first polishing endpoint in the first region and a second polishing endpoint in the second region, in which the second polishing endpoint is a polishing endpoint later than the first polishing endpoint; stopping progress of polishing in the first region by reducing pressure in a first pressure chamber in response to the first polishing endpoint being reached, and stopping progress of polishing in the second region by reducing pressure in a second pressure chamber in response to the second polishing endpoint being reached.

What is claimed is: 
     
         1 . A polishing method, comprising:
 rotating a polishing table that supports a polishing pad and pressing a substrate against a polishing surface of the polishing pad by a first pressure chamber and a second pressure chamber of a polishing head to polish the substrate;   outputting a film thickness monitoring signal in accordance to a film thickness of the substrate by a sensor during polishing of the substrate;   determining, based on the film thickness monitoring signal in each of a first region and a second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, a first polishing endpoint in the first region and a second polishing endpoint in the second region, the second polishing endpoint being a polishing endpoint later than the first polishing endpoint;   stopping progress of polishing in the first region by reducing pressure in the first pressure chamber in response to the first polishing endpoint being reached; and   stopping progress of polishing in the second region by reducing pressure in the second pressure chamber in response to the second polishing endpoint being reached.   
     
     
         2 . The polishing method according to  claim 1 ,
 wherein determining the first polishing endpoint and the second polishing endpoint based on the film thickness monitoring signal in each of the first region and the second region includes: determining the first polishing endpoint which is a time point at which an output value of the film thickness monitoring signal in the first region reaches a target signal value indicating a target film thickness, and determining the second polishing endpoint which is a time point at which an output value of the film thickness monitoring signal in the second region reaches the target signal value.   
     
     
         3 . The polishing method according to  claim 1 ,
 wherein stopping progress of polishing in the first region by reducing the pressure in the first pressure chamber in response to the first polishing endpoint being reached includes: stopping progress of polishing in the first region by releasing the first pressure chamber to atmosphere in response to the first polishing endpoint being reached.   
     
     
         4 . The polishing method according to  claim 1 , further comprising:
 increasing a polishing rate in the second region by increasing the pressure in the second pressure chamber in response to the first polishing endpoint being reached.   
     
     
         5 . The polishing method according to  claim 4 ,
 wherein increasing the polishing rate in the second region by increasing the pressure in the second pressure chamber in response to the first polishing endpoint being reached includes: in response to the first polishing endpoint being reached, calculating a correction pressure value in the second pressure chamber based on an output value of a film thickness monitoring signal in accordance to a film thickness of the second region at the first polishing endpoint and a target signal value indicating a target film thickness, and increasing the polishing rate in the second region by increasing the pressure in the second pressure chamber to the correction pressure value.   
     
     
         6 . The polishing method according to  claim 1 ,
 wherein determining the first polishing endpoint and the second polishing endpoint based on the film thickness monitoring signal in each of the first region and the second region includes:
 calculating, from a plurality of film thickness monitoring signals at a plurality of measurement points located in each of the first region and the second region, a signal average value which is an average value of output values of the plurality of film thickness monitoring signals; and 
 determining the first polishing endpoint and the second polishing endpoint based on the signal average value in each of the first region and the second region. 
   
     
     
         7 . A polishing device, comprising:
 a polishing table that supports a polishing pad;   a table motor that rotates the polishing table;   a polishing head hat has a first pressure chamber and a second pressure chamber and that presses a substrate against a polishing surface of the polishing pad;   a first pressure regulator that adjusts pressure in the first pressure chamber;   a second pressure regulator that adjusts pressure in the second pressure chamber;   a sensor that outputs a film thickness monitoring signal in accordance to a film thickness of the substrate; and   an operation control part that controls operations of the first pressure regulator and the second pressure regulator,   wherein the operation control part is configured to:
 determine, based on the film thickness monitoring signal in each of a first region and a second region on the substrate corresponding to the first pressure chamber and the second pressure chamber, a first polishing endpoint in the first region and a second polishing endpoint in the second region, the second polishing endpoint being a polishing endpoint later than the first polishing endpoint; 
 issue a command to the first pressure regulator to stop progress of polishing in the first region by reducing the pressure in the first pressure chamber in response to the first polishing endpoint being reached; and 
   issue a command to the second pressure regulator to stop progress of polishing in the second region by reducing the pressure in the second pressure chamber in response to the second polishing endpoint being reached.   
     
     
         8 . The polishing device according to  claim 7 , wherein the operation control part is configured to determine the first polishing endpoint which is a time point at which an output value of the film thickness monitoring signal in the first region reaches a target signal value indicating a target film thickness, and determine the second polishing endpoint which is a time point at which an output value of the film thickness monitoring signal in the second region reaches the target signal value. 
     
     
         9 . The polishing device according to  claim 7 , further comprising:
 a first atmospheric release valve that releases the first pressure chamber to atmosphere, wherein the operation control part is configured to issue a command to the first atmospheric release valve instead of the first pressure regulator to stop progress of polishing in the first region by releasing the first pressure chamber to atmosphere in response to the first polishing endpoint being reached.   
     
     
         10 . The polishing device according to  claim 7 , wherein the operation control part is configured to, in response to the first polishing endpoint being reached, issue a command to the first pressure regulator to stop progress of polishing in the first region by reducing pressure in the first pressure chamber of the polishing head corresponding to the first region, and issue a command to the second pressure regulator to increase a polishing rate in the second region by increasing the pressure in the second pressure chamber. 
     
     
         11 . The polishing device according to  claim 10 , wherein the operation control part is configured to, in response to the first polishing endpoint being reached, calculate a correction pressure value in the second pressure chamber based on an output value of a film thickness monitoring signal in accordance to a film thickness of the second region at the first polishing endpoint and a target signal value indicating a target film thickness, and issue a command to the second pressure regulator to increase the polishing rate in the second region by increasing the pressure in the second pressure chamber to the correction pressure value.  5   12 . The polishing device according to  claim 7 , wherein the operation control part is configured to:
 calculate, from a plurality of film thickness monitoring signals at a plurality of measurement points located in each of the first region and the second region, a signal average value which is an average value of output values of the plurality of film thickness monitoring  10  signals, and determine the first polishing endpoint and the second polishing endpoint based on the signal average value in each of the first region and the second region.