Fabrication of high aspect ratio through silicon vias (TSVs) by magnetic assembly of nickel wires

Three-dimensional (3D) integration of electronics and/or MEMS-based transducers is an emerging technology that vertically interconnects stacked dies using through silicon vias (TSVs). They enable the realization of devices with shorter signal lengths, smaller packages and lower parasitic capacitances, which can result in higher performance and lower costs of the system. This paper presents a novel low-cost fabrication technique for solid metal-filled TSVs using nickel wires as conductive path. The wires are placed in the via hole of a silicon wafer by magnetic self-assembly. This metal filling technique enables through-wafer vias with high aspect ratios and potentially eliminates characteristic cost drivers of the TSV production such as metallization processes, wafer thinning and general issues associated with thin-wafer handling.