Polishing apparatus and polishing method

Abstract

A polishing apparatus capable of accurately detecting a change in wafer condition is disclosed. The polishing apparatus includes: a polishing table for supporting a polishing pad having a polishing surface; a rotatable head body having a pressing surface arranged to press a wafer against the polishing surface; a retainer ring surrounding the pressing surface, the retainer ring being rotatable together with the head body and arranged to press the polishing surface; a non-rotating member that does not rotate together with the retainer ring; a vibration transmission member in contact with both the retainer ring and the non-rotating member; and a sensor secured to the non-rotating member.

What is claimed is: 
     
         1 . A polishing apparatus comprising:
 a polishing table for supporting a polishing pad having a polishing surface;   a rotatable head body having a pressing surface arranged to press a wafer against the polishing surface;   a retainer ring surrounding the pressing surface, the retainer ring being rotatable together with the head body and arranged to press the polishing surface;   a non-rotating member that does not rotate together with the retainer ring;   a vibration transmission member in contact with both the retainer ring and the non-rotating member; and   a sensor secured to the non-rotating member.   
     
     
         2 . The polishing apparatus according to  claim 1 , further comprising a condition detector configured to detect a change in condition of the wafer based on output signal of the sensor. 
     
     
         3 . The polishing apparatus according to  claim 2 , wherein the condition detector is configured to detect a point of change in surface condition of the wafer based on the output signal of the sensor. 
     
     
         4 . The polishing apparatus according to  claim 3 , wherein the condition detector is configured to detect the point of change in the surface condition which is a point in time at which an amplitude of the output signal of the sensor exceeds or falls below a threshold value. 
     
     
         5 . The polishing apparatus according to  claim 2 , wherein the condition detector is configured to detect a point of change in contact state between the wafer and the retainer ring based on the output signal of the sensor. 
     
     
         6 . The polishing apparatus according to  claim 5 , wherein the condition detector is configured to detect the point of change in the contact state between the wafer and the retainer ring which is a point in time at which the output signal of the sensor falls below a threshold value. 
     
     
         7 . The polishing apparatus according to  claim 1 , further comprising a local-load exerting device coupled to the non-rotating member, the local-load exerting device being configured to press the non-rotating member toward the retainer ring. 
     
     
         8 . The polishing apparatus according to  claim 1 , wherein the vibration transmission member includes a rotary ring having a plurality of rollers arranged along a circumferential direction of the retainer ring, the rotary ring being rotatable together with the retainer ring. 
     
     
         9 . The polishing apparatus according to  claim 1 , wherein the sensor is located above a downstream portion of the retainer ring with respect to a moving direction of the polishing surface. 
     
     
         10 . The polishing apparatus according to  claim 1 , wherein the sensor is located above an upstream portion of the retainer ring with respect to a moving direction of the polishing surface. 
     
     
         11 . The polishing apparatus according to  claim 1 , wherein the sensor comprises a plurality of sensors secured to the non-rotating member. 
     
     
         12 . A polishing method comprising:
 rotating a polishing table supporting a polishing pad;   pressing a wafer against a polishing surface of the polishing pad by a pressing surface of a head body, while rotating the head body;   pressing a retainer ring against the polishing surface, while rotating the retainer ring together with the head body and the wafer, the retainer ring being arranged around the wafer; and   measuring, by a sensor, a vibration transmitted from the retainer ring to a non-rotating member via a vibration transmission member, the sensor being secured to the non-rotating member.   
     
     
         13 . The polishing method according to  claim 12 , further comprising detecting a change in condition of the wafer based on output signal of the sensor. 
     
     
         14 . The polishing method according to  claim 13 , wherein detecting the change in condition of the wafer based on the output signal of the sensor comprising detecting a point of change in surface condition of the wafer based on the output signal of the sensor. 
     
     
         15 . The polishing method according to  claim 14 , wherein detecting the point of change in the surface condition based on the output signal of the sensor comprising detecting a point of change in the surface condition which is a point in time at which an amplitude of the output signal of the sensor exceeds or falls below a threshold value. 
     
     
         16 . The polishing method according to  claim 13 , wherein detecting the change in condition of the wafer based on the output signal of the sensor comprising detecting a point of change in contact state between the wafer and the retainer ring based on the output signal of the sensor. 
     
     
         17 . The polishing method according to  claim 16 , wherein detecting the point of change in contact state between the wafer and the retainer ring based on the output signal of the sensor comprising detecting a point of change in the contact state between the wafer and the retainer ring which is a point in time at which the output signal of the sensor falls below a threshold value.