Asymmetric Bidirectional Pulse Electrodeposition Enabling Super-Filling of Through Glass Vias With Large Aperture and High Aspect Ratio

Electrodeposition is the key to the vertical interconnection of through-glass vias (TGVs) in 3-D packaging. This article proposes an asymmetric bidirectional pulse electrodeposition strategy based on a Nitrotetrazolium Blue Chloride (NBTC) electrodeposition solution system, enabling high efficiency and defect-free super-filling of TGVs with large apertures, and high aspect ratios. The impact of varying parameters, including the amplitude of forward and reverse current density, the turn-on duration of reverse current, the duration of the pretreatment, and the concentration of sulfuric acid, on the deposition morphology and deposition rate of TGVs were examined. An optimized electrodeposition strategy was proposed to achieve an efficient and defect-free super-filling of TGVs with an aperture of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$75~\mu $ </tex-math></inline-formula>m and an aspect ratio of 5.5 within 180 min. This filling efficiency was observed to be enhanced by 400% in comparison to the most optimal outcomes previously reported. This will facilitate the development of electrodeposition approaches for the next generation of 3-D microelectronic packaging.