Apparatus for monitoring and controlling force applied on workpiece surface during electrochemical mechanical processing

Abstract

In one aspect, the present invention monitors a signal corresponding to a torque value of a motor that is used to maintain relative motion between a conductive top surface of a workpiece and a workpiece surface influencing device in the presence of physical contact between the conductive top surface of the workpiece and the workpiece surface influencing device. In another aspect, the present invention uses the signal to control a force applied to a top conductive surface of a workpiece during electrotreatment.

1 . An apparatus for monitoring force applied on a top conductive surface of a wafer during an electrotreatment process that uses an electrotreatment solution, comprising: 
 an electrode;    an electrotreatment dispenser for dispensing the electrotreatment solution;    a workpiece surface influencing device disposed between the top conductive surface and the electrode;    means for creating a potential difference between the electrode and the top conductive surface in the presence of the electrotreatment solution;    a device adapted to provide for relative movement of the wafer with respect to the workpiece surface influencing device in the presence of physical contact between the top conductive surface and the workpiece surface influencing device while the electrotreatment solution is disposed between the top conductive surface and the workpiece surface influencing device and while the potential difference between the electrode and the top conductive surface is maintained; and    a monitoring system adapted to monitor a frictional force occurring between the top conductive surface and the workpiece surface influencing device.    
   
   
       2 . The apparatus according to  claim 1 , further including: 
 a control system adapted to input a monitoring signal from the monitoring system and create an output signal that will control the frictional force occurring between the top conductive surface and the workpiece surface influencing device.    
   
   
       3 . The apparatus according to  claim 2 , wherein: 
 the device adapted to provide for relative movement is a wafer holding device that includes a spindle motor for rotating the wafer holder, the spindle motor maintaining the relative movement between the top conductive surface and the workpiece surface influencing device; and    the monitoring system monitors a signal that corresponds to a torque value of the spindle motor, such that the torque value of the spindle motor corresponds to the frictional force.    
   
   
       4 . The apparatus of  claim 3 , wherein the wafer holding device further includes a lateral drive motor to create lateral movement between the conductive surface and the workpiece surface influencing device.  
   
   
       5 . The apparatus according to  claim 4 , wherein the signal monitored by the monitoring system further includes a torque value of the lateral drive motor.  
   
   
       6 . The apparatus of  claim 3 , wherein the wafer holding device further includes a 
 a vertical drive motor that is used to fix a displacement between the conductive surface and the workpiece surface influencing device.    
   
   
       7 . The apparatus of  claim 1 , wherein the electrotreatment dispenser is adapted to dispense an electrolyte containing a conductive material therein and wherein the means for creating a potential difference create a depositing potential difference.  
   
   
       8 . The apparatus of  claim 1 , wherein the electrotreatment dispenser is adapted to dispense an etching or polishing solution and wherein the means for creating a potential difference create a polishing potential difference.  
   
   
       9 . The apparatus of  claim 1 , wherein the monitoring system is adapted to monitor the frictional force periodically during the processing of the wafer.  
   
   
       10 . The apparatus of  claim 2 , the device contains a wafer support to which pressure is applied on a backside in order to control the frictional force occurring between the top conductive surface and the workpiece surface influencing device.  
   
   
       11 . The apparatus of  claim 2 , the device moves vertically in order to control the frictional force occurring between the top conductive surface and the workpiece surface influencing device.  
   
   
       12 . The apparatus of  claim 2 , wherein the device is further adapted to provide for full-face plating of the wafer during a period of time with the relative motion.