Fine force control of actuators for chemical mechanical polishing apparatuses

Abstract

An actuator assembly ( 432 ) for positioning a pad ( 48 ) includes a first actuator assembly ( 440 ), a second actuator subassembly ( 442 ) and a control system ( 524 ). In one embodiment, the first actuator subassembly ( 440 ) includes a first core ( 502 ), and a conductor ( 504 ) secured to the first core ( 502 ), and the second actuator subassembly ( 442 ) includes a second core ( 506 ) spaced apart a component gap ( 444 ) from the first core ( 502 ). Further, the control system ( 524 ) directs current to the conductor ( 504 ) to attract the second core ( 506 ) to the first core ( 502 ). In one embodiment, the amount of current directed to the conductor ( 504 ) is calculated without measuring the component gap ( 444 ).

1 . A polishing apparatus for polishing a device, the polishing apparatus comprising: 
 a polishing pad positioned near the device;    a first attraction only actuator including a first core, a conductor secured to the first core, and a second core spaced apart a component gap from the first core, the second core being coupled to the polishing pad; and    a control system that controls the first attraction only actuator.    
     
     
         2 . The polishing apparatus of  claim 1  wherein the first core is somewhat “C” shaped.  
     
     
         3 . The polishing apparatus of  claim 1  wherein the first core is somewhat “E” shaped.