Autocatalytic Deposition of Nickel–Boron Diffusion Barrier onto Diazonium-Treated SiO₂ for High Aspect Ratio Through-Silicon Via Technology in 3D Integration

In the field of three-dimensional (3D) integration for microelectronics, achieving efficient and reliable deposition of multilayers within a high aspect ratio through-silicon vias (TSVs) is of paramount importance. Conventional physical-based techniques face several challenges in high aspect ratio TSV fabrication, from electrical isolation to copper electro-filling. In this study, we propose an innovative approach using an autocatalytic deposition process to address these challenges. Unlike multistep silane chemistry, our electroless nickel plating is accomplished on diazonium-treated SiO2 surfaces. Remarkably, the deposited nickel–boron film exhibits excellent step-coverage in high-aspect-ratio TSVs. The robust adhesion of the electrolessly deposited film, combined with its chemical composition, makes it suitable as a diffusion barrier and seed layer for direct electroplating of copper. Consequently, we demonstrate the feasibility of our Cu/Ni–B/SiO2 stack for efficient copper filling of high aspect ratio TSVs, despite the challenging presence of overhang formations at the via tops.