Wafer polishing head, system thereof, and method using the same

Abstract

A wafer polishing head is provided. The wafer polishing head includes a carrier head, a plurality of piezoelectric actuators disposed on the carrier head, and a membrane disposed over the plurality of piezoelectric actuators. The plurality of piezoelectric actuators is configured to provide mechanical forces on the membrane and generate an electrical charge when receiving counterforces of the mechanical forces through the membrane. A wafer polishing system and a method for polishing a substrate using the same are also provided.

What is claimed is: 
     
         1 . A wafer polishing head, comprising:
 a carrier head;   a plurality of piezoelectric actuators, disposed on the carrier head;   a membrane, disposed over the plurality of piezoelectric actuators, wherein the plurality of piezoelectric actuators are grouped into a plurality of groups, and the piezoelectric actuators in one group are all connected to a single voltage.   
     
     
         2 . The wafer polishing head of  claim 1 , further comprising:
 a plurality of plates, disposed between the membrane and the plurality of piezoelectric actuators.   
     
     
         3 . The wafer polishing head of  claim 2 , wherein the plurality of plates comprise a circular-shaped plate overlapping a central region of the membrane, and a plurality of ring-shaped plates individually surrounding the circular plate and sequentially disposed outward from the circular plate. 
     
     
         4 . The wafer polishing head of  claim 3 , wherein widths of the ring-shaped plates decrease as diameters of the ring-shaped plates increase. 
     
     
         5 . The wafer polishing head of  claim 3 , wherein the piezoelectric actuators in a same group have a substantially same distance to a center of the circular-shaped plate. 
     
     
         6 . The wafer polishing head of  claim 3 , wherein each of the ring-shaped plates is a monolithic structure, and is in contact with one of the plurality of groups of piezoelectric actuators. 
     
     
         7 . The wafer polishing head of  claim 3 , wherein each of the ring-shaped plates includes a plurality of sectors, being adjacent to one another. 
     
     
         8 . The wafer polishing head of  claim 7 , wherein each of the sectors of one of the plurality of ring-shaped plates is connected to one of the piezoelectric actuators in a same group. 
     
     
         9 . A wafer polishing system, comprising:
 a polishing head, configured to hold a substrate against a polishing pad, the polishing head comprising:
 a plurality of piezoelectric actuators, configured to provide mechanical forces against different regions of the substrate according to one or more voltages being received; and 
   a control unit, electrically connected to the plurality of piezoelectric actuators, and configured to receive a signal of an electrical charge generated by the plurality of piezoelectric actuators.   
     
     
         10 . The wafer polishing system of  claim 9 , further comprising:
 a platen, configured to allow the polishing pad to be disposed thereon and rotate during a polishing operation; and   slurry delivery unit, configured to supply slurry onto the polishing pad during the polishing operation.   
     
     
         11 . The wafer polishing system of  claim 9 , wherein the one or more voltages are adjusted by the control unit according to the signal of the electrical charge generated by the plurality of piezoelectric actuators. 
     
     
         12 . The wafer polishing system of  claim 9 , wherein different groups of the plurality of piezoelectric actuators are electrically isolated. 
     
     
         13 . The wafer polishing system of  claim 9 , wherein the polishing head further comprises:
 a membrane, disposed between the plurality of piezoelectric actuators and the substrate; and   a plurality of plates, disposed between the membrane and the plurality of piezoelectric actuators.   
     
     
         14 . The wafer polishing system of  claim 13 , wherein each of the plurality of piezoelectric actuator is disposed over a central region of each of the plurality of plates. 
     
     
         15 . The wafer polishing system of  claim 13 , wherein each of the plurality of piezoelectric actuator is disposed over a central region of each of the plurality of plates. 
     
     
         16 . The wafer polishing system of  claim 13 , wherein the plurality of plates is configured to rotate during a polishing operation, and a center of rotation of the plurality of plates is coincident with a center of the membrane or a center of the substrate. 
     
     
         17 . The wafer polishing system of  claim 13 , wherein the plurality of plates is configured to rotate during a polishing operation, and one of the plurality of piezoelectric actuator overlaps a center of rotation of the plurality of plates. 
     
     
         18 . A method for polishing a substrate, comprising:
 receiving a substrate;   holding the substrate with a polishing head on a polishing pad;   providing a first voltage to a first piezoelectric actuator and a second piezoelectric actuator of the polishing head to generate a first mechanical force and a second mechanical force on a first region and a second region of the substrate respectively;   generating a first signal corresponding to a first counterforce on the first piezoelectric actuator resulting from the first mechanical force and a second counterforce on the second piezoelectric actuator resulting from the second mechanical force;   comparing the first signal with a reference; and   adjusting the first voltage to the first piezoelectric actuator according to the first signal, to change the first mechanical force on the substrate if a result of the comparison between the first signal and the reference exceeds a tolerance.   
     
     
         19 . The method of  claim 18 , wherein distances of a center of the substrate and the first region and the center and the second region are substantially equal. 
     
     
         20 . The method of  claim 18 , further comprising:
 providing a second voltage to a third piezoelectric actuator of the polishing head to generate a third mechanical force on the substrate against the polishing pad, wherein distances of a center of the substrate and the first region and the center and the third region are different, and the first voltage and the second voltage are different.