Electroless Grafting of Polymer Insulation Layers in Through-Silicon Vias

A through-silicon via (TSV) with a polymeric insulation layer is promising in three-dimensional packaging technology because of its outstanding electrical properties. In this study, we present an electroless grafting method to realize the fabrication of a thin insulation layer in high aspect ratio TSVs. The proposed method is based on the polymerization of a vinyl monomer and an aryl diazonium salt on a silicon surface. Both poly(acrylic acid) and poly(methyl methacrylate) insulation layers were successfully prepared in TSVs to demonstrate the feasibility of the proposed method to fabricate hydrophilic and hydrophobic layers. The resulting polymer insulation layer exhibited high step coverage and superior dielectric properties. The electroless grafting method is a novel synthesis route to prepare polymeric insulation layers with outstanding dielectric properties in high aspect ratio TSVs.