Low-temperature refill process for through-silicon-vias (TSVs) in stacked ultra-thin chip-on-wafer by Aerosol Jet printed silver

The filling process of Through-Silicon Via (TSV) based on printed silver using the Aerosol Jet™ method is presented and discussed. TSVs with different diameters as via-last process in 18 μm ultra-thin ChipFilm™ dies, including a self-aligned etching process and their passivation are demonstrated. Daisy chain test structures on top of ChipFilm™ dies and on the bottom wafer are used for demonstration purposes. Moreover, the successful 3D-integration of an 18 μm ChipFilm™ die on the wafer using patterned photosensitive BCBs including a plasma treatment step right before stacking is presented. Finally, the work is concluded by demonstrating the results of electrical characterization of the filled and annealed TSVs at 180°C.