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Formation of electroless barrier and seed layers in a high aspect ratio through-Si vias using Au nanoparticle catalyst for all-wet Cu filling technology Fumihiro Inoue, Tomohiro Shimizu, Takumi Yokoyama, Hiroshi Miyake, Kazuo Kondo, Takeyasu Saito, Taro Hayashi, Shukichi Tanaka, Toshifumi Terui, Shoso Shingubara An all-wet process was achieved using electroless deposition of barrier and Cu seed layers for fabrication of a high aspect ratio through-Si via (TSV). Formation of a thin barrier metal layer of Ni-B, Co-B and Co-W-B is possible using a Au nanoparticle (AuNP) catalyst, which is densely adsorbed on the SiO sub(2 of the TSV sidewall. A silane coupling agent of 3-aminopropyl-triethoxysilane is effective for enhancement of the density of adsorption for AuNP. A conformal electroless Cu layer is deposited on the barrier layer by displacement plating without a catalyst. The adhesion strength between the electroless barrier layer and the SiO) sub(2) substrate is increased by annealing at 300 [deg]C. These results strongly suggest that an all-wet process for the formation of Cu-filled TSV with a high aspect ratio is practically possible. |