Journal of Applied Electrochemistry

, Volume 44, Issue 8, pp 945–952 | Cite as

A shielded rotating disk setup with improved current distribution

  • Feng Qiao
  • Xiaoxuan Sun
  • Alan C. West
Research Article
Part of the following topical collections:
  1. Electrodeposition


In contrast to wafer-scale experiments that can employ a sophisticated and well-optimized plating tool, coupon-scale studies of electrodeposition can be hindered by poor current distribution. The impact on primary current distribution and mass transfer of an insulating shield that can readily be used in a rotating disk setup is presented. Numerical simulations were employed to design an insulating shield assuming mass-transfer resistances were negligible. Several designs were fabricated and characterized using copper electrodeposition as the electrochemical reaction. Numerical and experimental results are consistent, and the shield is a convenient and effective way to achieve more uniform current distribution. However, the shield disturbs the uniform mass-transfer rates to the substrate surface that are achieved with a rotating disk. Rates are characterized experimentally, and design tradeoffs are discussed.


Electrodeposition Current distribution Uniformity Shield Electroplating 

List of symbols


Outer radius of the shield in unit mm


Inner radius of the shield in unit mm


Radius of the working electrode in unit mm


Local current density in unit mA/cm2


Electrolyte conductivity in unit S/m

\( \phi \)

Electrical field in the electrolyte


Normal unit vector


Applied current density in unit mA/cm2


Surface area of the working electrode in unit cm2


Surface area of the counter electrode in unit cm2


Axial coordinate


Exchange current density in unit mA/cm2


Cathodic charge transfer coefficient


Faraday constant, 96,485 C/mol


Potential on the working electrode in unit V


Temperature in unit K


Gas constant, 8.314 J/(K mol)


Wagner number


Distance between the anode and the cathode in unit mm


Linear average of thickness profile of copper deposit in unit nm


Number of data points of each thickness profile


Thickness of the copper deposit at ith data point in unit nm


Standard deviation of normalized thickness


Linear average of current–density profile


Radial position away from the center in unit mm


Slope of Levich plot


Number of electrons exchanged in reduction reaction in measuring Levich plots


Diffusion coefficient in unit cm2/s


Rotation speed of RDE in unit rpm


Kinematic viscosity in unit cm2/s


Bulk concentration of the Fe(III) complex, 1 mM


Limiting current density in unit mA/cm2


Thickness of the shield in unit mm



The authors are very grateful to Atotech Inc. for their financial support. We also thank Qian Zhang for her experimental contributions to this study.


  1. 1.
    Keyes RW (2006) The impact of Moore’s law. IEEE Solid-State Circuits Soc Newsl 11(5):25–27CrossRefGoogle Scholar
  2. 2.
    Armini S (2011) Cu electrodeposition on resistive substrates in alkaline chemistry: effect of current density and wafer RPM. J Electrochem Soc 158(6):D390–D394CrossRefGoogle Scholar
  3. 3.
    Bonou L et al (2002) Influence of additives on Cu electrodeposition mechanisms in acid solution: direct current study supported by non-electrochemical measurements. Electrochim Acta 47(26):4139–4148CrossRefGoogle Scholar
  4. 4.
    Kelly JJ, Tian C, West AC (1999) Leveling and microstructural effects of additives for copper electrodeposition. J Electrochem Soc 146(7):2540–2545CrossRefGoogle Scholar
  5. 5.
    Vas’ko VA et al (2004) Effect of organic additives on structure, resistivity, and room-temperature recrystallization of electrodeposited copper. Microelectron Eng 75(1):71–77CrossRefGoogle Scholar
  6. 6.
    Lee J-M et al (2004) Improvement of current distribution uniformity on substrates for microelectromechanical systems. J Micro/Nanolithogr MEMS MOEMS 3(1):146–151CrossRefGoogle Scholar
  7. 7.
    Tan Y-J, Lim KY (2003) Understanding and improving the uniformity of electrodeposition. Surf Coat Technol 167(2–3):255–262CrossRefGoogle Scholar
  8. 8.
    Willey MJ, West AC (2006) Microfluidic studies of adsorption and desorption of polyethylene glycol during copper electrodeposition. J Electrochem Soc 153(10):C728–C734CrossRefGoogle Scholar
  9. 9.
    Newman J (1966) Resistance for flow of current to a disk. J Electrochem Soc 113(5):501–502CrossRefGoogle Scholar
  10. 10.
    Szánto DA et al (2008) The limiting current for reduction of ferricyanide ion at nickel: the importance of experimental conditions. AIChE J 54(3):802–810CrossRefGoogle Scholar
  11. 11.
    Vidal R, West AC (1995) Copper electropolishing in concentrated phosphoric acid: I. Experimental findings. J Electrochem Soc 142(8):2682–2689CrossRefGoogle Scholar
  12. 12.
    Tobias CW, Wijsman R (1953) Theory of the effect of electrode resistance on current density distribution in electrolytic cells. J Electrochem Soc 100(10):459–467CrossRefGoogle Scholar
  13. 13.
    Newman J, Thomas-Alyea KE (2012) Electrochemical systems. Wiley, HobokenGoogle Scholar
  14. 14.
    Price D, Davenport W (1980) Densities, electrical conductivities and viscosities of CuSO4/H2SO4 solutions in the range of modern electrorefining and electrowinning electrolytes. Metall Trans B 11(1):159–163CrossRefGoogle Scholar
  15. 15.
    Newman J (1966) Current distribution on a rotating disk below the limiting current. J Electrochem Soc 113(12):1235–1241CrossRefGoogle Scholar
  16. 16.
    Gallaway JW, Willey MJ, West AC (2009) Acceleration kinetics of PEG, PPG, and a triblock copolymer by SPS during copper electroplating. J Electrochem Soc 156(4):D146–D154CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  1. 1.Department of Chemical EngineeringColumbia UniversityNew YorkUSA

Personalised recommendations