Chemical-mechanical planarization tool force calibration method and system

Abstract

The methods and devices described below allow users of CMP tools to quickly calibrate Spindle Force, Wafer Force, and Retaining Ring Force using mechanisms, load cells, a control computer, and force equations. The control computer can test a variety of pressures in the inflatable seal or the inflatable membrane, depending on the wafer carrier configuration, to determine a unique calibration in real time for the particular wafer carrier that is being tested and used during the polishing process.

1 . A system for calibrating a CMP tool comprising: 
 a CMP tool;    a first mechanism disposed within the CMP tool capable of measuring a downward force of a spindle generated by an actuation system;    a second mechanism disposed within the CMP tool capable of measuring a retaining ring force component of said downward force; and    a control computer programmed to: 
 control, measure, and record the downward force of the spindle generated by the actuation system;  
 measure and record the retaining ring force component of the downward force; and  
 determine a wafer force component of said downward force.  
   
   
   
       2 . The system of claimed  1  wherein the first mechanism comprises a first load cell able to measure the downward force of the spindle.  
   
   
       3 . The system of  claim 1  wherein the second mechanism comprises a second load cell able to measure the retaining ring force component of the downward force.  
   
   
       4 . The system of  claim 1  wherein the control computer is further programmed to distinguish between total downward force from the spindle and the force acting on the wafer using the downward force of the spindle and the retaining ring force component.  
   
   
       5 . The system of  claim 1  wherein the actuation system comprises a bellows.  
   
   
       6 . The system of  claim 5  wherein the actuation system further comprises a bellows pressure generating the downward force and the control computer is further programmed to: 
 measure the bellows pressure corresponding to the downward force;    record the bellows pressure corresponding to the downward force; and    generate a calibration table corresponding bellows pressure to downward force.    
   
   
       7 . The system of  claim 5  wherein the control computer is further programmed to control the bellows pressure.  
   
   
       8 . The device of  claim 1  wherein the retaining ring force component is generated by an inflatable ring seal having an inflatable seal pressure in a wafer carrier.  
   
   
       9 . The system of  claim 8  wherein the control computer is further programmed to create a table corresponding the retaining ring force component to an inflatable seal pressure generating the retaining ring force component.  
   
   
       10 . The system of  claim 8  wherein the control computer is further programmed to control the retaining ring force component.  
   
   
       11 . A system for calibrating a CMP tool comprising: 
 a CMP tool capable of generating a downward force on a wafer carrier using an actuation system;    a first mechanism disposed within the CMP tool capable of measuring a wafer force component of the downward force;    a second mechanism disposed within the CMP tool capable of measuring a retaining ring force component of the downward force; and    a control computer programmed to: 
 measure and record the wafer force component; and  
 measure and record the retaining ring force component.  
   
   
   
       12 . The system of claimed  11  wherein the first mechanism comprises a first load cell able to measure the wafer force component.  
   
   
       13 . The system of  claim 11  wherein the second mechanism comprises a second load cell able to measure the retaining ring force component.  
   
   
       14 . The system of  claim 1  wherein the second mechanism comprises a plurality of load cells able to measure the wafer force component.