Conformal Cu Seed Layer Formation by Electroless Deposition in Non-Bosch through Silicon Vias

The electroless deposition (ELD) method was applied to deposit the Cu seed layer on non-Bosch through silicon vias (TSVs) to overcome structural drawbacks such as the overhang and high aspect ratio that lead to the discontinuity of the film. Pretreatment conditions were optimized and convection system was adopted. Optimal time was achieved by populating the Cu nuclei at the bottom of the vias, and the continuity and conformality of the seed layer were enhanced by finding the optimal rotating speed. Finally, conformal Cu seed layer was obtained, on which Cu was successfully filled by electrodeposition (ED) without voids.