Conformal Electroless Deposition of Barrier and Cu Seed Layers for Realizing All-Wet TSV Filling Process

Abstract

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 SiO2 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.