Device and method for polishing a specimen

Abstract

The present invention relates to a device for polishing a specimen (104, 204). The device comprises a polishing platen (101, 201) rotatable about an axis, a polishing pad (103, 203) attached to the polishing platen (101, 201), a specimen holder (105, 205) for holding the specimen (104, 204) against the polishing pad (103, 203), means (107, 110, 207, 212) for measuring a physical quantity in a plurality of positions on the polishing pad (103, 203), the physical quantity being indicative of the moisture or the friction, and means (116, 119, 120, 121, 213, 215, 216, 217) for dispensing a polishing suspension, based on values of the measured physical quantity, to the plurality of positions on the polishing pad (103, 203). The invention also relates to a method for polishing a specimen (104, 204).

1 . A device for polishing a specimen, comprising:
 a polishing platen rotatable about an axis,   a polishing pad attached to the polishing platen, and   a specimen holder for holding the specimen against the polishing pad,   
       wherein the device further comprises:
 means for measuring a physical quantity in a plurality of positions on the polishing pad, the physical quantity being indicative of moisture or friction, and 
 means for dispensing a polishing suspension, based on values of the measured physical quantity, to a plurality of positions on the polishing pad. 
 
     
     
         2 . The device according to  claim 1 , wherein the physical quantity is the resistance on the polishing pad, and the means for dispensing a polishing suspension is configured to dispense the polishing suspension to a position on the polishing pad if in said position the value of the resistance is larger than a first threshold value. 
     
     
         3 . The device according to  claim 1 , wherein the physical quantity is capacitance between opposite sides of the polishing pad, and the means for dispensing a polishing suspension is configured to dispense the polishing suspension to a position on the polishing pad if in said position the value of the capacitance is smaller than a second threshold value. 
     
     
         4 . The device according to  claim 1 , wherein the physical quantity is friction on the surface of the polishing pad, and the means for dispensing a polishing suspension is configured to dispense the polishing suspension to a position on the polishing pad if in said position the value of the friction is larger than a third threshold value. 
     
     
         5 . The device according to  claim 1 , wherein the means for measuring a physical quantity comprises a sensor arranged in contact with the surface of the polishing pad, and means for moving the sensor between the plurality of positions on the polishing pad. 
     
     
         6 . The device according to  claim 5 , wherein the means for moving the sensor comprises an arm arranged above the polishing pad and an actuator for moving the sensor along the arm. 
     
     
         7 . The device according to  claim 1 , wherein the means for measuring a physical quantity comprises an array of sensors arranged in contact with the surface of the polishing pad. 
     
     
         8 . The device according to  claim 5 , wherein the sensor comprises at least two electrical contact elements arranged in contact with the surface of the polishing pad, and the means for measuring a physical quantity comprises means for measuring the resistance between two of the at least two electrical contact elements. 
     
     
         9 . The device according  claim 8 , wherein the means for measuring a physical quantity comprises means for measuring capacitance between one of the at least two electrical contact elements and the polishing platen. 
     
     
         10 . The device according to  claim 5 , wherein the means for measuring a physical quantity comprises a compression element for pressing the sensor against the surface of the polishing pad. 
     
     
         11 . The device according to  claim 5 , wherein the means for measuring a physical quantity comprises means for measuring the lateral force acting on the sensor. 
     
     
         12 . The device according to  claim 1 , wherein the means for dispensing a polishing suspension comprises a spray nozzle arranged above the polishing pad and means for moving the spray nozzle between the plurality of positions on the polishing pad. 
     
     
         13 . The device according to  claim 12 , wherein the means for moving the spray nozzle comprises an arm arranged above the polishing pad and an actuator for moving the spray nozzle along the arm. 
     
     
         14 . The device according to  claim 1 , wherein the means for dispensing a polishing suspension comprises an array of spray nozzles arranged above the polishing pad. 
     
     
         15 . A method for polishing a specimen, comprising:
 holding the specimen with a specimen holder against a polishing pad that is attached to a polishing platen;   rotating the polishing platen about an axis;   measuring a physical quantity indicative of moisture or friction in a plurality of positions on the polishing pad; and   dispensing a polishing suspension, based on values of the measured physical quantity, to the plurality of positions on the polishing pad.