Communication-Defect-Free Filling Of High Aspect Ratio Through Vias In Ultrathin Glass

We report an all-solution, simple process (DC plating with single additive) for metallizing high aspect ratio (AR = 5 and AR similar to 12) through vias in ultrathin glass (thickness similar to 100 um). Highly uniform and continuous Cu seed layer is first achieved by a simple surface modification, Sn/Pd catalyst adsorption and Cu electroless plating. Subsequently, the vias are filled by DC plating in the presence of a single additive nitrotetrazolium blue chloride (NBT). The strong inhibition effect of NBT is exploited to first bridge the center of the vias followed by filling of two blind vias. (C) The Author(s) 2018. Published by ECS.