Study of low resistance TSV using electroless plated copper and tungsten-alloy barrier

We studied a low temperature deposition of tungsten-alloy barrier and copper layers only by electroless plating, with an aim of realizing low resistance TSV with a high aspect ratio. We succeeded in successive deposition of W-Ni-P barrier layer and Cu on SiO
₂
. Furthermore, we found that the addition of Cl ions to SPS- and PEG-plating bath significantly improved the conformal deposition property even for a few mum in diameter TSVs with the aspect ratio higher than 10.