‘L-Cell’ A Novel Device for Plating Process Diagnostics

1. ‘L-Cell’ A Novel Device for Plating Process Diagnostics L-Chem, Inc. Shaker Heights, OH 44120 www.L-Chem.com

2. Introducing a novel, multi-purpose device that provides: • Process parameters • Process diagnostics • Fully automated • No expertise required • Fast (2 min./test)

3. OUTLINE • Rationalle and need • Current tecnology and its defficiencies • The L-Cell - principles and description • Examples • Conclusions

4. Issues in Plating • Predictive Design • Meeting Specs., Optimization • Process Control and Maintenance • Environmental and Health • New Materials

5. FUTURE: L-Cell Available Tools } Computer Aided Design Software -‘Cell-Design’ • Predictive Design • Optimization • Process Control PAST: • Hull-Cell • Electroanalytical Techniques- Polarization studies Conductivity Titration (reactant conc.)

6. Often Missing Numerical ‘Solver’ Limitations of CAD Software INPUT • Cell configuration • Cell • Anodes • Racks and Shields OUTPUT • Current distribution • Deposit thickness distribution • Potential distribution • Overpotential (polarization) • Parasitic reaction rates • Alloy composition • Part’s evolving shape • Deposit texture • Operating Conditions • current or voltage • (DC or Periodic) • temperature • flow • Process Properties • Electrode polarization • Electrolyte conductivity • Diffusivity

7. Issues with Obtaining Process Data using Conventional Approach • Strong dependence on trace additives • Proprietary formulations • Lack of fundamental mechanistic understanding • Laboratory experiments often do not duplicate process • conditions • Flow dependence • Cost: • Potentiostat ~ $ 20,000 - 40,000 • Rotating disk electrode ~ $ 10,000 • PhD investigator ~ $ 100K/yr i V

8. Limitations of the Hull-Cell • Qualitative • Current distribution is inherently inaccurate – varies with material • No quantitative data

9. The L-Cell Provides: • Comprehensive electrochemical process parameters • Polarization curves • Kinetics parameters • Conductivity • Process diagnostics: • Indication of process variation due to • additives consumption • contamination • Tool for process adjustment using a small (50 ml) volume • Sample plated at a number of different and precisely known current densities for visual and analytical off-line testing • Composition of alloy – partial currents • Thickness measurements – current efficiency as f(i) • Fully automated, fast (2 min.) experiment designed for non-experts • Equipment is relatively inexpensive

10. THE L-Cell – Principle of Operation • Multi-electrode cartridge and a cell that allows a separate current feed to each segment • Electronics to provide a different and precisely measured current density to each segment • Automated data acquisition and analysis Plated cartridge with segmented electrodes Cross-section

11. The L-Cell: Table-top design

12. The multi-pin connector

13. The L-Cell: Table-top design

14. The L-Cell: Table-top design Watts Nickel Testing

15. Design of the L-Cell Potential distribution: Reference electrode ‘Cell-Design’ Modeling Top View (cross-section): Anode: oxygen evolution Segmented cathode (plated cartridge) Current distribution – different between segments but uniform on each segment

16. THE L-Cell – Analytical Approach Across the cell Overpotentials Unknowns: Cathodic polarization curve: iK =f (hA) Cathodic overpotentials (i0, aC, aA) Conductivity Measure: Segmental current densities Voltages (including reference electrodes) Conductivity Voltage balances Data analysis Butler-Volmer fit kinetics parameters (i0, aC, aA)

17. CB CE DATA ANALYSIS Butler-Volmer: (pure kinetics, No transport limitations) = CB CE Mass transport included: Here, i0 is measured at CB and:

18. DATA ANALYSIS Tafel approximation: Equivalent mass transport boundary layer thickness

19. DATA ANALYSIS ik = Equivalent pure ‘kinetics‘ current derived from the measured current density, i

20. The L-Cell System

21. DATA AQUISITION 0.18 1.25 5.0 8.3 14.2 18.1 29.0 1.09 3.02 22. 6

22. Polarization curve Kinetics Parameters Cu deposition Copper sulfate 0.5 M pH=2

23. Cu deposition Copper sulfate 0.5 M pH=2 100 ppm PEG

24. Comparing two tests Cu deposition Copper sulfate 0.5 M pH=2 Compare with: 100 ppm PEG Pure Cu w/PEG

25. Specification of acceptable deviation w/PEG

26. Copper deposition from copper sulfate No additives; pH=2

27. No PEG 100 ppm PEG Copper deposition from copper sulfate pH=2 Log i [mA/cm2]

28. Overpotential, η[V] Nickel Deposition from a standard Nickel Watts Electrolyte

29. Overpotential, η[V] Nickel Deposition from a standard Nickel Watts Electrolyte

30. Wagner Number

31. Throwing Power

32. The L-Cell Provides: Summary - • Process properties: Polarization, Kinetics, Conductivity • Use ‘regular production’ solution • By-pass specialized testing – no special expertise needed • No need to scan v-i, or apply transients – use steady-state data • Fast (2 min.), completely automated • Produces deposit samples plated at different current densities • Process diagnostics tool