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Conformal electroless deposition of barrier and seed layers was studied for fabrication of a high aspect ratio through-Si via (TSV). Formation of a thin barrier metal layer of Ni-B and Co-B is possible using a Au nanoparticle (Au-NP) catalyst, which is densely adsorbed on the SiO 2 of the TSV sidewall. A silane coupling agent of 3-aminopropyl-triethoxysilane is effective for enhancement of the adsorption density of Au-NP. A conformal electroless Cu layer is deposited on the barrier layer by displacement plating without a catalyst. These results strongly suggest that an all-wet process for the formation of Cu-filled TSV with a high aspect ratio is possible.

The formation of a diffusion barrier layer in a through-Si via (TSV) has been studied with a combination of nanoparticle catalyst and electroless plating (ELP). We used Au-nanoparticles (Au-NPs) or Pd-nanoparticles (Pd-NPs) as catalysts for ELP of Ni- and Co-alloy barrier layers. We studied deposition of Ni–B and Co–B films in high-aspect-ratio (AR) TSV. Then, we succeeded in controlling the deposition profile of Ni–B in a high-AR TSV by the addition of bis(3-sulfopropyl)-disulfide (SPS). SPS turned out to be an inhibitor of electroless plating of Ni–B. On the other hand, the Co–B film was deposited conformally without additive. The electrical resistivity of Cu after annealing Cu/barrier stacked structure suggests that Co–B has better thermal stability than Ni–B.

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