Electroplating chemistry on-line monitoring and control system

What is claimed is:

 

1. A method for monitoring and controlling an electroplating process, the method comprising: (a) obtaining a sample of electrolyte, comprising an acid, a metal salt, and one or more organic components, from the electroplating process; (b) removing an organic fraction of the sample of electrolyte to give a substantially organic-free electrolyte sample; (c) determining the density of the substantially organic-free electrolyte sample; (d) determining at least one of the conductivity and the light absorption of the substantially organic-free electrolyte sample; (e) comparing at least one of the conductivity and the light absorption measurement of the substantially organic-free electrolyte sample with the density in order to determine a concentration value for each of the metal salt and the acid; and (f) adjusting conditions of the electroplating process in response to a comparison of the concentration value for each of the metal salt and the acid, with an associated target value. 

 

2. The method of claim 1, wherein the sample of electrolyte is obtained directly from a plating cell of the electroplating process. 

 

3. The method of claim 1, wherein the sample of electrolyte is obtained directly from a separate sampling vessel of the electroplating process. 

 

4. The method of claim 1, wherein the metal salt is a copper salt. 

 

5. The method of claim 4, wherein the copper salt is copper sulfate. 

 

6. The method of claim 1, wherein the acid is sulfuric acid. 

 

7. The method of claim 1, further comprising determining a chloride ion concentration measurement for the substantially organic-free electrolyte sample before (f), wherein (f) further includes an adjustment of the electroplating process with respect to a comparison of the chloride ion concentration measurement with an associated target value. 

 

8. The method of claim 1, wherein removing an organic fraction of the sample of electrolyte includes a filtration. 

 

9. The method of claim 8, wherein a charcoal medium is used for the filtration. 

 

10. The method of claim 8, wherein molecular sieves are used for the filtration. 

 

11. The method of claim 1, wherein (b) further comprises an HPLC analysis of the organic fraction, and wherein (f) further includes an adjustment of the electroplating process with respect to a comparison of at least one concentration of an organic bath constituent, obtained from the HPLC analysis, with a target concentration value for the organic bath constituent. 

 

12. The method of claim 1, wherein adjusting conditions of the electroplating process comprises adjusting electroplating apparatus hardware. 

 

13. The method of claim 12, wherein adjusting electroplating apparatus hardware comprises adjusting an electrolyte composition. 

 

14. The method of claim 12, wherein adjusting electroplating apparatus hardware comprises adjusting an electrical current flow. 

 

15. The method of claim 12, wherein adjusting electroplating apparatus hardware comprises adjusting a field shaping apparatus. 

 

16. The method of claim 12, wherein adjusting electroplating apparatus hardware comprises adjusting a voltage level. 

 

17. The method of claim 12, wherein adjusting electroplating apparatus hardware comprises adjusting a wafer handling apparatus. 

 

18. The method of claim 12, wherein adjusting electroplating apparatus hardware comprises adjusting a relative orientation of an electrode with a counter electrode. 

 

19. The method of claim 1, further comprising returning the substantially organic-free electrolyte sample to a central chemistry vessel of the electroplating process. 

 

20. The method of claim 1, wherein (a)-(f) comprise an analysis and said analysis occurs at regular time intervals of between about 0.3 and 10 minutes. 

 

21. An apparatus for controlling an electroplating process, the apparatus comprising: (a) a device for sampling electrolyte from the electroplating process, wherein the electrolyte comprises an acid, a metal salt, and one or more organic components; (b) a module for removing an organic fraction from the electrolyte to give a substantially organic-free electrolyte sample; (c) a densimeter for determining a density of the substantially organic-free electrolyte sample; (d) a module for determining at least one of conductivity and light absorption for the substantially organic-free electrolyte sample; and (e) an associated logic for: (i) using at least one of the conductivity and the light absorption in the substantially organic-free electrolyte sample and the density measurement in order to determine a concentration value for each of the acid and the metal salt; (ii) controlling the electroplating process based on comparison of the concentration value for each of the metal salt and the acid, with an associated target value.
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