Superconformal Nickel Deposition in Through Silicon Vias: Experiment and Prediction
Trevor Braun, Daniel Josell, Thomas P. Moffat, Hyo Jong Lee, SH Kim
This work examines the filling of Through Silicon Vias (TSV) by Ni deposition from a NiSO4 + NiCl2 + H3BO3 electrolyte containing a branched polyethyleneimine suppressor previously. Feature filling occurs through the coupling of transport limited suppressor adsorption and its consumption by potential dependent metal deposition. The former couples with surface topography to yield a sharp transition from passive to active deposition within the TSV. The transition is associated with significant incorporation of the suppressor, or its components, within the Ni deposit that results in grain refinement evident by electron back scatter diffraction (EBSD). In contrast, active deposition on the lower sidewalls exhibits columnar growth that tends towards a <110> texture along the growth direction. Potential programs that progressively shift the passive-active transition upward to optimize feature filling were examined. The evolution of feature filling and the deposit microstructure are compared to predictions of a three- dimensional model based on a suppressor-derived, s-shaped negative differential resistance (S- NDR) mechanism. The model uses adsorption and consumption kinetics obtained from voltammetric measurements of the critical potential associated with suppression breakdown. Good agreement between experiment and simulation is demonstrated.
, Josell, D.
, Moffat, T.
, Lee, H.
and Kim, S.
Superconformal Nickel Deposition in Through Silicon Vias: Experiment and Prediction, Journal of the Electrochemical Society, [online], https://doi.org/10.1149/2.0911807jes
(Accessed December 3, 2023)