Fabrication of through-silicon-via (TSV) by copper electroplated in an electrolyte mixed with supercritical carbon dioxide

In this study we have performed complete filling of through-silicon vias (TSVs) by supercritical carbon dioxide (sc-CO₂)-enabled Cu electroplating process for applications in 3D ICs. The sc-CO₂ technique makes use of the special features of supercritical fluids, which combine benefits of different states of matter. The effects of different supercritical pressure and current density parameters were investigated, discussed, and the results were compared to traditional electroplating method containing additives, a common practice in PCB industry. Results showed that the best quality structure for this study was achieved at 2000 psi and 3 A/dm², which could withstand a current of 10 A before burnout, without the addition of any additives or surfactants and a relatively short electroplating time of 3 hours was also found.