Superconformal Bottom-Up Cobalt Deposition in High Aspect Ratio Through Silicon Vias

This work demonstrates and models controlled bottom-up Co filling of Through Silicon Vias (TSVs) based on the coupling of suppressor breakdown and surface topography. Deposition was performed in a CoSO 4 + CoCl 2 + H 3 BO 3 electrolyte with a branched polyethyleneimine (PEI) as a suppressing additive. Voltammetric measurements, including the impact of rotation rate and suppressor concentration on the rate of metal deposition, were used to quantify the interplay between metal deposition and suppressor adsorption. The derived kinetics were used in a model based on additive derived S-shaped negative differential resistance (S-NDR) to predict bottom-up filling of patterned features. The predictions, including the impact of deposition potential and additive concentration on the feature filling, are shown to match experimental results for filling of TSVs. This work parallels previous work with Ni and extends previous understanding and application of additive derived S-NDR that also includes prediction and demonstration of superconformal, bottom-up deposition and filling of TSVs with Cu, Au and Zn.