Journal of Applied Electrochemistry, Vol.44, No.8, 945-952, 2014
A shielded rotating disk setup with improved current distribution
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.