Methods and apparatus for controlling and/or measuring additive concentration in an electroplating bath

Abstract

A method for measuring a target constituent of an electroplating solution using an electroanalytical technique is set forth in which the electroplating solution includes one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique. The method comprises a first step in which an electroanalytical measurement cycle of the target constituent is initiated by providing an energy input to a pair of electrodes disposed in the electroplating solution. The energy input to the pair of electrodes is provided for at least a predetermined time period corresponding to a time period in which the electroanalytical measurement cycle reaches a steady-state condition. In a subsequent step, an electroanalytical measurement of the energy output of the electroanalytical technique is taken after the electroanalytical measurement cycle has reached the steady-state condition. The electroanalytical measurement is then used to determine an amount of the target constituent in the electroplating solution. An automatic dosing system that includes the foregoing method and/or one or more known electroanalytical techniques in a close-loop system is also set forth.

1 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising the steps of: 
 initiating an electroanalytical measurement cycle of the target constituent by providing an energy input to at least a pair of electrodes disposed in the electroplating solution, the energy input to the pair of electrodes being provided for at least a predetermined time period corresponding to a time period in which the analytical measurement cycle reaches a steady-state condition;    taking an electroanalytical measurement of the energy output of the electroanalytical technique after the analytical measurement cycle has reached the steady-state condition;    using the electroanalytical measurement to determine an amount of the target constituent in the electroplating solution.    
     
     
         2 . A method as claimed in    claim 1    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         3 . A method as claimed in    claim 1    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         4 . A method as claimed in    claim 1    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         5 . A method as claimed in    claim 1    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         6 . A method as claimed in    claim 1    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         7 . A method as claimed in    claim 1    wherein the target constituent comprises a suppressor.  
     
     
         8 . A method as claimed in    claim 1    wherein the electroanalytical technique comprises titration.  
     
     
         9 . A method as claimed in    claim 8    wherein the electroplating solution is used as the diluent and the target constituent is used as the titrant.  
     
     
         10 . A method as claimed in    claim 8    wherein a virgin make-up of the electroplating solution is used as the diluent and the electroplating solution is used as the titrant.  
     
     
         11 . A method for executing a measurement of a suppressor of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique to thereby generate erroneous suppressor measurements, the method comprising the steps of: 
 initiating an electroanalytical measurement cycle to measure the suppressor by providing an energy input to at least one pair of electrodes disposed in the electroplating solution, the energy input to the pair of electrodes being provided for at least a predetermined time period corresponding to a time period in which the analytical measurement cycle reaches a steady-state condition;    taking an electroanalytical measurement of the energy output of the electroanalytical technique after the analytical measurement cycle has reached the steady-state condition;    using the electroanalytical measurement to determine an amount of the suppressor in the electroplating solution.    
     
     
         12 . A method as claimed in    claim 11    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         13 . A method as claimed in    claim 11    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         14 . A method as claimed in    claim 11    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         15 . A method as claimed in    claim 11    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         16 . A method as claimed in    claim 11    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         17 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising the steps of: 
 a) removing an amount of electroplating bath from an electroplating reactor;    b) executing an electroanalytical technique measurement using the electroplating bath removed in Step a, ensuring that the measurement is taken during the electroanalytical technique process as it approaches or reaches a steady-state;    c) comparing the resulting measurement with a calibration curve to determine an amount of the target constituent in the electroplating bath.    
     
     
         18 . A method as claimed in    claim 17    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         19 . A method as claimed in    claim 17    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         20 . A method as claimed in    claim 17    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         21 . A method as claimed in    claim 17    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         22 . A method as claimed in    claim 17    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         23 . A method as claimed in    claim 17    wherein the target constituent comprises a suppressor.  
     
     
         24 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or ? 
     
     
         27 . A method as claimed in    claim 24    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         28 . A method as claimed in    claim 24    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         29 . A method as claimed in    claim 24    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         30 . A method as claimed in    claim 24    wherein the target constituent comprises a suppressor.  
     
     
         31 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising the steps of: 
 a) removing an amount of electroplating bath from an electroplating reactor;    b) adding an amount of virgin make-up solution of the electroplating solution to the amount of electroplating bath removed in Step a;    c) executing an electroanalytical technique measurement process using the electroplating bath formed in Step b, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    d) adding an amount of the target constituent to the amount of electroplating bath;    e) executing an electroanalytical technique measurement process using the electroplating bath of Step d, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    f) repeating Steps d and e as necessary to generate a slope, or to otherwise gather enough data to answer a logic criteria;    g) comparing the measurement results obtained during one or more cycles of Steps d and e to a calibration curve; and    h) calculating the amount of the target constituent based on the comparison made in Step g.    
     
     
         32 . A method as claimed in    claim 31    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         33 . A method as claimed in    claim 31    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         34 . A method as claimed in    claim 31    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         35 . A method as claimed in    claim 31    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         36 . A method as claimed in    claim 31    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         37 . A method as claimed in    claim 31    wherein the target constituent comprises a suppressor.  
     
     
         38 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising the steps of: 
 a) removing an amount of electroplating bath from an electroplating reactor;    b) providing an amount of virgin make-up solution;    c) executing an electroanalytical technique measurement process using the virgin make-up solution formed in Step b, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    d) adding an amount of the electroplating bath removed in Step b to the virgin make-up solution formed in Step b;    e) executing an electroanalytical technique measurement process using the electroplating bath of Step d, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    f) repeating Steps d and e as necessary to generate a slope, or to otherwise gather enough data to answer a logic criteria;    g) comparing the measurement results obtained during one or more cycles of Steps d and e to a calibration curve; and    h) calculating the amount of the target constituent based on the comparison made in Step g.    
     
     
         39 . A method as claimed in    claim 38    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         40 . A method as claimed in    claim 38    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         41 . A method as claimed in    claim 38    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         42 . A method as claimed in    claim 38    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         43 . A method as claimed in    claim 38    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         44 . A method as claimed in    claim 38    wherein the target constituent comprises a suppressor.  
     
     
         45 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising the steps of: 
 a) removing an amount of electroplating bath from an electroplating reactor;    b) providing an amount of virgin make-up solution;    c) executing an electroanalytical technique measurement process using the virgin make-up solution formed in Step b, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    d) adding an amount of the electroplating bath removed in Step b to the virgin make-up solution formed in Step b;    e) executing an electroanalytical technique measurement process using the electroplating bath of Step d, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    f) adding an amount of the target constituent to the solution formed in Step d;    g) executing an electroanalytical technique measurement process using the solution formed in of Step f, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    h) repeating Steps f and g to generate a measurement curve;    i) calculating the amount of the target constituent based on the measurement curve obtained in Step h.    
     
     
         46 . A method as claimed in    claim 45    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         47 . A method as claimed in    claim 45    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         48 . A method as claimed in    claim 45    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         49 . A method as claimed in    claim 45    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         50 . A method as claimed in    claim 45    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         51 . A method as claimed in    claim 45    wherein the target constituent comprises a suppressor.  
     
     
         52 . A method for executing a measurement of a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents whose by-products skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising the steps of: 
 a) removing an amount of electroplating bath from an electroplating reactor;    c) executing an electroanalytical technique measurement process using the virgin make-up solution formed in Step a, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    d) adding an amount of virtual make-up solution of the electroplating bath to the amount of electroplating bath removed in Step a;    e) executing an electroanalytical technique measurement process using the electroplating bath of Step d, ensuring that the measurement is taken during the electroanalytical technique measurement process as it approaches or reaches a steady-state;    f) calculating the slope all of the measurements taken in Steps c and d;    g) comparing the measurement results obtained during Step f to a calibration curve to calculate the amount of the target constituent.    
     
     
         53 . A method as claimed in    claim 52    wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.  
     
     
         54 . A method as claimed in    claim 52    wherein the electroanalytical technique comprises cyclic voltammetric stripping.  
     
     
         55 . A method as claimed in    claim 52    wherein the electroanalytical technique comprises chronoamperometry.  
     
     
         56 . A method as claimed in    claim 52    wherein the electroanalytical technique comprises chronopotentiometry.  
     
     
         57 . A method as claimed in    claim 52    wherein the electroanalytical technique comprises linear sweeps of the energy input that are performed at a slow rate and then calibrated versus concentration of the target constituent.  
     
     
         58 . A method as claimed in    claim 52    wherein the target constituent comprises a suppressor.  
     
     
         59 . An apparatus for maintaining a concentration level of a target constituent of an electroplating bath comprising: 
 a bath sample extraction unit connected to automatically removed an amount of electroplating bath from an electroplating tool;    an electroanalysis unit connected to receive the bath sample obtained by the bath sample extraction unit;    a constituent dosing supply unit connected to provide an amount of the target constituent to the electroplating bath of the electroplating tool;    a programmable control unit connected to communicate with a) the bath sample extraction unit for control of the extraction of the bath sample from the electroplating bath of the electroplating tool and supply of the bath sample to be electroanalysis unit, b) the electroanalysis unit to execute an electroanalytical technique to determine an amount of the target constituent in the bath sample, and c) the constituent dosing supply unit to provide an amount of the target constituent to the electroplating bath of the electroplating tool based on the amount of the target constituent measured in the bath sample through the use of the electroanalytical technique.