Polishing apparatus and polishing method for polishing a periphery of a substrate

Abstract

A polishing apparatus capable of accurately detecting a polishing end point of a periphery of a substrate, such as a wafer, is disclosed. The polishing apparatus includes a polishing head configured to press a polishing tool against the periphery of the substrate on a substrate holding surface. The polishing head includes a pressing member configured to press the polishing tool against the periphery of the substrate, and a shear-force detection sensor configured to detect a shear force acting on the pressing member and output an index value indicating a magnitude of the shear force. An operation controller has a memory storing a program configured to determine a polishing end point at which the index value reaches a threshold value, and a processer configured to execute the program.

What is claimed is: 
     
         1 . A polishing apparatus for polishing a periphery of a substrate, comprising:
 a substrate holder having a substrate holding surface for holding the substrate, the substrate holder being configured to rotate the substrate holding surface;   a polishing head configured to press a polishing tool against the periphery of the substrate on the substrate holding surface; and   an operation controller configured to control operations of the substrate holder and the polishing head,   wherein the polishing head comprises:
 a pressing member configured to press the polishing tool against the periphery of the substrate; and 
 a shear-force detection sensor configured to detect a shear force acting on the pressing member due to a frictional resistance between the polishing tool and the periphery of the substrate, the shear-force detection sensor being configured to output an index value indicating a magnitude of the shear force, and 
   wherein the operation controller comprises a memory storing a program configured to determine a polishing end point at which the index value reaches a threshold value, and a processer configured to execute the program.   
     
     
         2 . The polishing apparatus according to  claim 1 , wherein the shear-force detection sensor comprises a tactile sensor including a sensor element having carbon microcoils, and the sensor element is fixed to the pressing member. 
     
     
         3 . The polishing apparatus according to  claim 2 , wherein the sensor element further has an elastic resin block, and the carbon microcoils are located in the elastic resin block. 
     
     
         4 . The polishing apparatus according to  claim 3 , wherein:
 the polishing head has a polishing-tool pressing surface configured to support a back side of the polishing tool and to press the polishing tool against the periphery of the substrate; and   at least a part of the polishing-tool pressing surface is constituted by the sensor element.   
     
     
         5 . The polishing apparatus according to  claim 1 , wherein the shear-force detection sensor comprises a load cell coupled to a back side of the pressing member. 
     
     
         6 . A polishing method of polishing a periphery of a substrate, comprising:
 holding the substrate on a substrate holding surface;   rotating the substrate holding surface together with the substrate;   polishing the periphery of the substrate by pressing a polishing tool with a pressing member of a polishing head against the periphery of the substrate;   during polishing of the periphery of the substrate, detecting a shear force acting on the pressing member due to a frictional resistance between the polishing tool and the periphery of the substrate by a shear-force detection sensor;   determining a polishing end point at which an index value indicating a magnitude of the shear force reaches a threshold value; and   terminating polishing of the periphery of the substrate based on the polishing end point.   
     
     
         7 . The polishing method according to  claim 6 , wherein the shear-force detection sensor comprises a tactile sensor including a sensor element having carbon microcoils, and the sensor element is fixed to the pressing member. 
     
     
         8 . The polishing method according to  claim 7 , wherein the sensor element further has an elastic resin block, and the carbon microcoils are located in the elastic resin block. 
     
     
         9 . The polishing method according to  claim 8 , wherein:
 the polishing head has a polishing-tool pressing surface configured to support a back side of the polishing tool and to press the polishing tool against the periphery of the substrate; and   at least a part of the polishing-tool pressing surface is constituted by the sensor element.   
     
     
         10 . The polishing method according to  claim 6 , wherein the shear-force detection sensor comprises a load cell coupled to a back side of the pressing member.