Methods 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 closed-loop system is also set forth.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of International PCT Patent Application No. PCT/US99/09659, designating the U.S., filed May 3, 1999, entitled METHODS AND APPARATUS FOR CONTROLLING AND/OR MEASURING ADDITIVE CONCENTRATION IN AN ELECTROPLATING BATHaare, Enthone based Ethone-based chemistry, are described below. These exemplary steps or “recipes” are illustrative and further steps may be added (e.g., for electronic conditioning) as required, chemical volumes may be changed, etc. Also, it will be recognized that the following methods may be combined with one another.

EXEMPLARY METHOD I

In accordance with the first exemplary method in which no titration is used, current or some other aspect of the CA plot is related to a calibration curve. To this end, the following process steps may be implemented:

• • 1. Remove an amount of electroplating bath (i.e., 50 mls) from the electroplating reactor,
  • 2. Perform a CA measurement using the electroplating bath removed in Step 1, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above); and
  • 3. Compare the resulting measurement with the calibration curve to determine the amount of additive (i.e., suppressant) in the bath.

Exemplary Method I is advantageous in that it is a very simple process to implement. However, a disadvantage of this approach is the fact that it requires a predetermined calibration curve.

EXEMPLARY METHOD II

The second exemplary method involves concentration titration using the unknown bath as the diluent and the suppressor as the titrant. To this end, the following process steps may be implemented:

• • 1. Remove an amount of electroplating bath (i.e., 50 mls) from the electroplating reactor;
  • 2. Perform a CA measurement using the electroplating bath removed in Step 1, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 3. Add 5%-25% (0.0075-0.0375 mls) suppressor;
  • 4. Perform a CA measurement using the solution formed in Step 3, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 5. Repeat Steps 3 and 4 as necessary to generate a slope, or to otherwise gather enough data to answer a logic criteria (e.g., is the concentration below the “knee”);
  • 6. Compare the measurement results obtained during one or more cycles of Steps 3 and 4 to the calibration curve; and
  • 7. Calculate the concentration based on the comparison made in Step 6.

One advantage of Exemplary Method II is that the titration does not require either AE carrier syringe or a VMS Syringe syringe. However, it has been found that the accuracy of this method decreases at high initial suppressor concentrations. This is due to the fact that the slope decreases with this particular Enthone chemistry.

EXEMPLARY METHOD III

The third exemplary method involves concentration titration using the diluted unknown bath as the diluent and suppressor as the titrant. To this end, the following process steps may be implemented:

• • 1. Remove an amount of electroplating bath (i.e., 10 mls) from the electroplating reactor;
  • 2. Add an amount of VMS (40 mls)+100% (b 0.4 mls) carrier to the amount of electroplating bath removed in Step 1;
  • 3. Perform a CA measurement using the solution formed in Step 2, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 4. Add 5%-25% (0.0075-0.0375 mls) suppressor;
  • 5. Perform a CA measurement using the solution formed in Step 4, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 6. Repeat Steps 4 and 5 as necessary to generate a slope, or to otherwise gather enough data to answer a logic criteria (e.g., is the concentration below the “knee”);
  • 7. Compare the measurement results obtained during one or more cycles of Steps 4 and 5 to the calibration curve; and
  • 8. Calculate the concentration based on the comparison made in Step 7.

Exemplary Method III exhibits an increased accuracy over Exemplary Method II by diluting the electroplating bath sample to the more accurate end of the calibration curve.

EXEMPLARY METHOD IV

The fourth exemplary method involves concentration titraton using Virgin Make-Up solution (VMS) as the diluent and the unknown bath as the titrant. To this end, the following process steps may be implemented;

• • 1. Remove an amount of electroplating bath (i.e., 10 mls) from the electroplating reactor;
  • 2. Mix a solution of VMS (40 mls)+100% (0.4 mls);
  • 3. Perform a CA measurement using the solution formed in Step 2, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 4. Add a quantity of the unknown bath removed in Step 1 (10-25% of the initial VMS volume (4-10 mls) to VMS;
  • 5. Perform a CA measurement using the solution formed in Step 4, ensuring that the measurement is taken during the CA process is it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 6. Repeats Steps 4 and 5 until a sufficient curve is generated; and
  • 7. Compare the curve generated in Steps 4-6 to a calibration curve to calculate Calculate the constituent concentration.

It should be noted that the accuracy of Exemplary Method IV will decrease significantly if the bath solution is too dilute,

EXEMPLARY METHOD V

The fifth exemplary method involves concentration titration using using linear slope analysis. To this end, the following process steps may be implemented:

• • 1. Remove an amount of electroplating bath (i.e., 10 mls) from the electroplating reactor;
  • 2. Provide a solution of VMS (50 mis mls)+100% (0.5 mls);
  • 3. Perform a CA measurement using the solution formed in Step 2, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above).
  • 4. Add an amount of the electroplating bath removed in Step 1 to the solution formed in Step 2;
  • 5. Perform a CA measurement using the solution formed in Step 4, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state) e.g., by using the preferred process steps set forth above);
  • 6. Add 10-25% suppressor to the solution (0.015-0.037 mls);
  • 7. Perform a CA measurement using the solution formed in Step 6, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 8. Repeat Steps 6 and 7 to generate a measurement curve; and
  • 9. Using a linear fit or other appropriate curve, calculate the amount of the suppressor in the unknown electroplating bath.

This exemplary method works well in those instances in which a linear region may be obtained. Additionally, it does not require a calibrator curve and, further, is less dependent on bath carrier solution than the foregoing exemplary methods.

EXEMPLARY METHOD VI

The sixth exemplary method involves dilution titration and comprises performing a CA test on the unknown bath, dividing the unknown bath by diluting it with Virgin Make-UpSolution (VMS), performing another CA test, comparing the measurable with a logic criteria (e.g., matching the calibration curve or until a specific delta change has occurred, etc.). To this end, the following process steps may be implemented:

• • 1. Remove an amount of electroplating bath (i.e., 40 mls) from the electroplating reactor;
  • 2. Perform a CA measurement using the solution formed in Step 1, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 3. Add 10-20% (4-8 mls) of the VMS plus corresponding carrier (0.04-0.08 mls) to the unknown electroplating bath removed in Step 1,
  • 4. Perform a CA measurement using the solution formed in Step 3, ensuring that the measurement is taken during the CA process as it approaches or reaches a steady-state steady state (e.g., by using the preferred process steps set forth above);
  • 5. Calculate the slope of the measurement taken in Steps 2 and 4;
  • 6. Compare with a logic criteria (e.g., compare the slope with the calibration curve); and
  • 7. Repeat steps 3-5 on the same sample until the degree of resolution is achieved.

Exemplary Method VI is advantageous in that it is relatively easy to implement. Further, the method can be repeated until the sensitive range of the calibrated curve is reached, thereby providing for a wide range of measurement sensitivity and resolution.

AUTOMATIC DOSING SYSTEM

As the microelectronics fabrication industry moves toward widespread use of electroplating, particularly of micro-structures microstructures, there is an increased need for highly accurate dosing systems that replenish the various components of the electropath bath. To this end, dosing systems have been developed for use with electroplating tools, that are used at microelectronic fabrication facilities. Most known systems, however, execute the dosing function using open-loop, predetermined models that replenish the electroplating bath constituents based on emperically empirically determined data. Such systems may be suitable for certain electroplating processes, but becomes less viable as new device requirements impose more rigorous standards on the make-up of the electroplating bath.

More accurate control of both of the plating both constituents may be obtained using a dosing system that employs measurement feedback to ascertain the proper quantity of a bath bath's constituents. An exemplary feedback dosing system is illustrated in FIG. 9. As shown, the dosing system, shown generally at 100, includes a central processor 105 that is used to control the operations necessary to perform the following functions: 1) extract a sample of the electroplating bath that is to be analyzed; 2) execute an electroanalytical technique on the electroplating bath sample; 3) calculate the amount of the electroplating bath constituent present in the sample based on the results of the electroanalytical technique; and 4) use the resulting calculation to automatically control the supply of an amount of the constituent to replenish the electroplating bath, raising the constituent concentration to a predetermined level.

In order to execute the foregoing functions, the central processor 105 is connected to interact with and exchange information with a number of units the and systems. A bath sample extraction unit 110 is connected for control by the central processor 105. The bath sample extraction unit 110 is connected to receive electroplating solution along line 120 from the principal electroplating bath 115 in response to control signals/commands received from the central processor 105 along communication link 125. In response to such control signals/commands, the bath sample extraction unit 110 provides the bath sample to either an electroanalysis unit 130 or to an optional titration system 135.

Both the electroanalysis unit 130 and the optional titration system 135 are under the control of the central processor 105. The central processor 105 coordinates the activities of the electroanalysis unit 130 and titration system 135 to execute the desired electroanalytical technique. The electroanalytical technique can be any of the known techniques, or can be one or more of the inventive techniques disclosed herein.

The central processor 105 that acquires the requisite data based on the electroanalytical technique to directly calculate or otherwise determine in a relative manner the concentration of the plating bath constituent bath constituent. Based on this calculation/determination, the central processor 105 directs one or more constituent dosing supply units 140 to provide the necessary amount of the constituent (or amount of solution containing the constituent) to the electroplating bath 115, thus completing the feedback control process.

It will be recognized that the inventive electroanalytical techniques described above can be implemented in a manual, semi-automatic semiautomatic, or completely automatic manner. Dosing system 100 is merely provided as an illustrative, yet novel manner in which to implement one or more known and/or inventive electroanalytical techniques described above.

Numerous modifications may be made to the foregoing system without departing from the basic teachings thereof. Although the present invention has been described in substantial detail with reference to one or more specific embodiments, those of skill in the art to the the the will recognize that changes may be made thereto without departing form the scope and spirit of the invention as set forth in the appended claims.

Claims

1. A method for measuring a target constituent of an electroplating solution using a plating and/or stripping electroanalytical technique, the electroplating solution including one or more constituents that form a byproduct that skews an initial plating and/or stripping response to an energy input of the electroanalytical technique for a first time period beyond which such skewing is negligible, the method comprising the steps of:

initiating a plating and/or stripping electroanalytical measurement cycle for measurement of the target constituent by providing electrical energy to at least a pair of electrodes disposed in the electroplating solution, the electrical energy input to the pair of electrodes being provided to either plate or strip a metal to or from at least one of the electrodes for at least a predetermined time period that extends beyond the first time period;

taking an electroanalytical measurement of the energy output of the electroanalytical technique after the first time period has elapsed and before the predetermined time period has elapsed;

using the electroanalytical measurement to determine an amount of the target constituent in the electroplating solution so as to reduce the effect of the skewing of the initial plating and/or stripping response caused by the one or more by-products in calculating the amount of the target constituent.

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 measuring a suppressor for an electroplating solution using a metal plating and/or stripping electroanalytical technique, the electroplating solution including one or more constituents that form a by-product that operates as a pseudo-suppressor during an initial electrical energy input of the electroanalytical technique for a first-time period beyond which such skewing is negligible, the method comprising the steps of:

initiating a plating and/or stripping electroanalytical measurement cycle to measure the suppressor by providing an electrical energy input to at least one pair of electrodes disposed in the electroplating solution, the electrical energy input to the pair of electrodes being provides to either plate or strip a metal to or from at least one of the electrodes for at least a predetermined time period that extends beyond the first time period;

taking an electroanalytical measurement of the energy output of the electroanalytical technique after the first time period has elapsed and before the predetermined time period has elapsed;

using the electroanalytical measurement taken after the first time period has elapsed and before the predetermined time period has elapsed to determine an amount of the suppressor in the electroplating solution so as to reduce the effect of the skewing of the initial plating and/or stripping response caused by the pseudo-suppressor in calculating the amount of the suppressor.

12. A method as claimed in claim 11 wherein the electroanalytical technique comprises cyclic pulsed voltametric shipping.

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 measuring a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents that form a by-product that skews an initial electrical response to an energy input of the electroanalytical technical for a first time period beyond which such skewing is negligible, the method comprising the steps of:

a) removing an amount of electroplating solution from an electroplating reactor;

b) executing a metal plating and/or stripping electroanalytical technique using the electroplating solution removed in Step a, ensuring that a measurement is taken during the electroanalytical technique process after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

c) comparing the measurement taken in Step b with a calibration curve to determine an amount of the target constituent in the electroplating solution.

18. A method as claimed in claim 17 wherein the electroanalytical technique comprises cyclic pulsed voltametric stripping.

19. A method as claimed in claim 17 wherein the electroanalytical technique comprises cyclic voltametric 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 measuring a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents that form a by-product that skews an initial plating and/or stripping response to an energy input of the electroanalytical technique for a first time period beyond which such skewing is negligible, the method comprising the steps of:

a) removing an amount of electroplating solution from an electroplating reactor;

b) executing a metal plating and/or stripping electroanalytical technique using the electroplating solution removed in Step a, ensuring that a measurement is taken during the electroanalytical technique after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

c) adding an amount of the target constituent to the amount of electroplating solution;

d) executing a metal plating and/or stripping electroanalytical technique using the electroplating bath of Step c, ensuring that a measurement is taken during the electroanalytical technique after plating or stripping power has been provided for a predetermined period of time that extends beyond the period;

e) repeating Steps c and d as necessary to generate a slope, or to otherwise gather enough data to answer a logic criteria;

f) comparing the measurement results obtained during one or more cycles of Steps c and d to a calibration curve; and

g) calculating the amount of the target constituent based on the comparison made in Step f whereby the effect of the skewing of the initial plating and/or stripping response caused by the by-product on the calculation is reduced.

25. A method as claimed to claim 24 wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.

26. A method as claimed in claim 24 wherein the electroanalytical technique comprises cyclic voltammetric stripping.

27. A method as claimed in claim 24 wherein the electroanalytical technique comprises chronoamperometry.

28. A method as claimed to 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 measuring a target constituent of an electroplating solution using a plating and/or stripping electroanalytical technique, the electroplating solution including one or more constituents that form a by-product that skews an initial plating and/or stripping response to an energy input of the electroanalytical technique for a first time period beyond with such skewing is negligible, the method comprising the steps of:

a) removing an amount of electroplating solution from an electroplating reactor;

b) adding an amount of virgin make-up solution of the electroplating solution to the amount of electroplating solution removed in Step a;

c) executing a metal plating and/or stripping electroanalytical technique using the electroplating solution formed in Step b, ensuring that a measurement is taken during the electroanalytical technique after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

d) adding an amount of the target constituent to the amount of electroplating solution;

e) executing a metal plating and/or stripping electroanalytical technique using the electroplating solution of Step d, ensuring that a measurement is taken during the electroanalytical technique measurement process after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

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 whereby the effect of the skewing of the initial plating and/or stripping response caused by the by-product on the calculation is reduced.

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 voltametric 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 measuring a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents that form a by-product that skews an initial plating and/or stripping response to an energy input of the electroanalytical technique for a first time period beyond which such skewing is negligible, the method comprising the steps of:

a) removing an amount of electroplating solution from an electroplating reactor;

b) providing an amount of virgin make-up solution;

c) executing a metal plating and/or stripping electroanalytical technique using the virgin make-up solution formed in Step b, ensuring that a measurement is taken during the electroanalytical technique after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

d) adding an amount of the electroplating solution removed in Step b to the virgin make-up solution formed in Step b;

e) executing a metal plating and/or stripping electroanalytical technique measurement process using the electroplating solution of Step d, ensuring that a measurement is taken during the electroanalytical technique measurement process after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

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 calibration curve; and

h) calculating the amount of the target consistent based on the comparison made in Step g whereby the effect of the skewing of the initial plating and/or stripping response caused by the by-product on the calculation is reduced.

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 measuring a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution including one or more constituents that form a by-product that skews an initial plating and/or stripping response to an energy input of the electroanalytical technique for a first time period beyond which such skewing is negligible, the method comprising the steps of:

a) removing an amount of electroplating solution from an electroplating reactor;

b) providing an amount of virgin make-up solution;

c) executing a metal plating and/or stripping electroanalytical technique using the virgin make-up solution formed by Step b;

d) adding an amount of the electroplating solution removed in Step a to the virgin make-up solution formed in Step b;

e) executing a metal plating and/or stripping electroanalytical technique using the electroplating solution of Step d, ensuring that a measurement is taken during the electroanalytical technique measurement process after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

f) adding an amount of the target constituent to the solution formed in Step d;

g) executing a metal plating and/or stripping electroanalytical technique using the solution formed in of Step f, ensuring that a measurement is taken during the electroanalytical technique measurement process after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

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 whereby the effect of the skewing of the initial plating and/or stripping response caused by the by-product on the calculation is reduced.

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 measuring a target constituent of an electroplating solution using an electroanalytical technique the electroplating solution including one or more constituents that form by a by-product that skews an initial plating and/or stripping response to an energy input of the electroanalytical technique for a first time period beyond which such skewing is negligible, the method comprising the steps of:

a) removing an amount of electroplating solution 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;

d) adding an amount of virgin make-up solution to the amount of electroplating solution removed in Step a;

e) executing a plating and/or stripping electroanalytical technique measurement process using the electroplating solution of Step d, ensuring that a measurement is taken during the electroanalytical technique measurement process after plating or stripping power has been provided for a predetermined period of time that extends beyond the first time period;

f) calculating the slope of measurements taken in Steps c and d whereby the effect of the skewing of the initial plating and/or stripping response caused by the byproduct on the calculation is reduced;

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. A method for measuring a target constituent of an electroplating solution using an electroanalytical technique, the electroplating solution comprising one or more by-products that skew an initial electrical response to an energy input of the electroanalytical technique, the method comprising:

applying the electroanalytical technique using metal plating or stripping parameters that facilitate measurement taking during a time at which the skewing of the initial electrical response is negligible;

taking electroanalytical measurements during the time at which the skewing of the initial electrical response is negligible;

using the electroanalytical measurements that are taken during the time at which the skewing of the initial electrical response is negligible to determine an amount of the target constituent in the electroplating solution.

60. A method as claimed in claim 59 wherein the electroanalytical technique comprises cyclic pulsed voltammetric stripping.

61. A method as claimed in claim 59 wherein the electroanalytical technique comprises cyclic voltammetric stripping.

62. A method as claimed in claim 59 wherein the electroanalytical technique comprises chronoamperometry.

63. A method as claimed in claim 59 wherein the electroanalytical technique comprises chronopotentiometry.

64. A method as claimed in claim 59 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.

65. A method as claimed in claim 59 wherein the target constituent comprises a suppressor.

66. A method as claimed in claim 59 wherein the electroanalytical technique comprises titration.

67. A method as claimed in claim 66 wherein the electroplating solution is used as the diluent and the target constituent is used as the titrant.

68. A method as claimed in claim 66 wherein a virgin make-up of the electroplating solution is used as the diluent and the electroplating solution is used as the titrant.