Modeling Extreme Bottom-Up Filling of Through Silicon Vias

Extreme bottom-up superfilling of through silicon vias (TSV) was recently described wherein deposition occurs on the bottom surface of the vias with negligible deposition on their sidewalls or the field around them. The process uses a deposition suppressing adsorbate subject to breakdown through the metal deposition reaction. Positive feedback associated with this suppressor disruption coupled with resistive electrolyte losses underlies the bottom-up feature filling dynamic by distributing the applied potential between the interface double layer and the bulk electrolyte in a time dependent manner. A simple pseudo steady state model that links suppressor disruption with the potential drop between the reference and working electrodes in resistive electrolytes is shown to capture essential aspects of the bottom-up filling process. Understanding the coupling of potential and additive concentration gradients provides a rational design strategy for bottom-up filling of recessed surface features that offers to minimize unneeded deposition on the substrate surface thereby substantially decreasing fill times and improving materials utilization.