High-speed via hole filling using electrophoresis of Ag nanoparticles

As an alternative to conventional electroplating, we propose TSV filling using the electrophoresis of metal nanoparticles. Colloidal solution of Ag nanoparticles having a high zeta potential has been designed and made up. Via holes for the test experiment were prepared in a photoresist layer on a Au film which acts as anode. Ag nanoparticles were completely filled into the cavities of depth of 30 µm and diameter of 10 µm within one minute. After annealing at 250 °C, the electric conductivity was 1.57 × 10⁻⁵ [Ω·cm]. These results demonstrate the potentials of the application of electrophoresis of metal nanoparticles to high speed TSV filling.