Adjustable dosing algorithm for control of a copper electroplating bath

Abstract

A method and apparatus for supplying a dose to an electrolyte solution including measuring the time after adding fresh solution, measuring the Amp-hours after adding fresh solution, measuring the number of substrates processed by the solution, calculating the volume of a dose to supply to the solution based on the time, Amp-hours, and number of substrates processed, and adding the dose to the solution.

1 . A method for supplying a dose to an electrolyte solution, comprising: 
 measuring the time after adding fresh solution;    measuring the total Amp-hours used during electroplating after adding fresh solution;    measuring the number of substrates processed after adding fresh solution;    calculating a dose to supply to the electrolyte solution based on the time, the total Amp-hours, and the number of substrates processed; and    adding the dose to the electrolyte solution.    
   
   
       2 . The method of  claim 1 , further comprising draining a small volume of fluid from the electrolyte solution when the total Amp-hours exceeds a set target.  
   
   
       3 . The method of  claim 2 , wherein small volume is less than about 2 liters.  
   
   
       4 . The method of  claim 1 , wherein calculating the dose uses calculations that do not interrelate the Amp-hours, number of substrates, or time.  
   
   
       5 . The method of  claim 1 , further comprising resetting the time, the total Amp-ours, and the number of substrates processed to zero after the adding a dose to the electrolyte solution.  
   
   
       6 . A method for supplying a dose to an electrolyte solution, comprising: 
 measuring the loss of a volume of fluid from a solution vessel;    measuring the time after adding fresh solution;    measuring the total Amp-hours used during electroplating after adding fresh solution;    measuring the number of substrates processed by the electrolyte solution;    calculating a dose to supply to the electrolyte solution based on the time, the total Amp-hours, and the number of substrates processed; and    adding the dose to the electrolyte solution.    
   
   
       7 . The method of  claim 6 , further comprising draining a small volume of fluid from the solution.  
   
   
       8 . The method of  claim 7 , wherein the small volume of fluid is about 2 liters or less.  
   
   
       9 . The method of  claim 6 , wherein calculating the volume of the dose uses calculations that do not interrelate the Amp-hours, number of substrates, or time.  
   
   
       10 . The method of  claim 6 , further comprising resetting a time measurement.  
   
   
       11 . The method of  claim 6 , further comprising resetting the Amp-hour measurement.  
   
   
       12 . The method of  claim 6 , further comprising resetting the number of substrate measurement.  
   
   
       13 . The method of  claim 6 , further comprising establishing an initial time, Amp-hour, and substrate number measurement.  
   
   
       14 . The method of  claim 6 , wherein the adding the dose to the solution occurs when the loss of a volume of fluid is greater than about 2 L.  
   
   
       15 . The method of  claim 6 , wherein the adding the dose to the solution occurs when the time is equal to or greater than about 2 days.  
   
   
       16 . The method of  claim 6 , wherein the adding the dose to the solution occurs when the Amp-hours is greater than about 100 Amp-hours.  
   
   
       17 . The method of  claim 6 , wherein the adding the dose to the solution occurs when the number of substrates processed is greater than 200.  
   
   
       18 . A method for dosing an electroplating bath, comprising: 
 monitoring total Amp-hours used during electroplating;    monitoring total evaporation loss during electroplating;    dosing water and chemicals to the electroplating bath after either the total Amp-hours or the total evaporation loss exceed set targets; and then    resetting both the total Amp-hours and the total evaporation loss to zero.    
   
   
       19 . The method of  claim 18 , further comprising draining some of the electroplating bath after the total Amp-hours exceeds the set targets and before the dosing water and chemicals.  
   
   
       20 . The method of  claim 19 , wherein the dosing the water and chemicals restores the electroplating bath to a target concentration of chemicals.