Device and method for moistening a polishing pad

Abstract

The present invention relates to a device for moistening a polishing pad. The moistening device comprises measuring means for measuring a physical quantity that is indicative of the moisture in the polishing pad, and dispensing means for dispensing a polishing suspension, based on a value of the measured physical quantity, on a surface of the polishing pad. The measuring means and the dispensing means, are enclosed by a housing having a contact surface for contacting the surface of the polishing pad. The present invention also relates to a device for polishing a specimen and a method for moistening a polishing pad.

1 . A device for moistening a polishing pad, comprising:
 measuring means for measuring a physical quantity that is indicative of the moisture in the polishing pad, and   dispensing means for dispensing a polishing suspension, based on a value of the measured physical quantity, on a surface of the polishing pad, characterised in that the device comprises:   a housing that encloses the measuring means and the dispensing means, the housing having a contact surface for contacting the surface of the polishing pad.   
     
     
         2 . The device according to  claim 1 , characterised in that the housing is essentially cylindrical. 
     
     
         3 . The device according to  claim 1 , characterised in that the physical quantity is the resistance on the polishing pad. 
     
     
         4 . The device according to  claim 3 , characterised in that the measuring means comprises two electrical contact elements arranged on the contact surface and a measuring instrument that is configured to measure the resistance between the two electrical contact elements. 
     
     
         5 . The device according to  claim 3 , characterised in that the dispensing means is configured to dispense the polishing suspension on the surface of the polishing pad if the value of the resistance is larger than a first threshold value. 
     
     
         6 . The device according to  claim 1 , characterised in that the physical quantity is the capacitance between opposite sides of the polishing pad. 
     
     
         7 . The device according  claim 6 , characterised in that the measuring means comprises an electrical contact element arranged on the contact surface and a measuring instrument that is configured to measure the capacitance between the electrical contact element and a polishing platen on which the polishing pad is placed. 
     
     
         8 . The device according to  claim 6 , characterised in that the dispensing means is configured to dispense the polishing suspension on the surface of the polishing pad if the value of the capacitance is smaller than a second threshold value. 
     
     
         9 . The device according to  claim 1 , characterised in that the dispensing means comprises a container for holding the polishing suspension and a hose having a first end connected to the container and a second end arranged in connection with the contact surface. 
     
     
         10 . The device according to  claim 9 , characterised in that the dispensing means comprises a nozzle connected to the second end of the hose. 
     
     
         11 . The device according to  claim 10 , characterised in that the dispensing means comprises a valve or a micropump arranged in connection with the container, the hose or the nozzle, and a control unit that is configured to control the operation of the valve or the micropump. 
     
     
         12 . The device according to  claim 1 , characterised in that the device comprises a power source for supplying electrical power to the measuring means and the dispensing means. 
     
     
         13 . 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 comprising a plurality of specimen cavities for holding one or more specimens against a surface of the polishing pad, characterised in that the device comprises:   a device according to  any of the preceding claims  inserted into one of the specimen cavities so that the contact surface is in contact with the surface of the polishing pad.   
     
     
         14 . The device according to  claim 13 , characterised in that the specimen holder comprises pressing means for pressing the contact surface against the surface of the polishing pad. 
     
     
         15 . A method for moistening a polishing pad, characterised in that the method comprises:
 arranging a device according  claim 1  to in a specimen cavity of a specimen holder,   arranging the contact surface of the device in contact with a surface of a polishing pad that is attached to a polishing platen,   rotating the polishing platen about an axis,   measuring with the device a physical quantity that is indicative of the moisture in the polishing pad, and   dispensing with the device a polishing suspension, based on a value of the measured physical quantity, on the surface of the polishing pad.