Through-silicon via arrays manufactured by photo assisted electrochemical etching and copper electroplating under SC-CO2 environment

This paper reports fabrication of through silicon vias (TSV) by photo-assisted electrochemical etching (PAECE) and copper electroplating under supercritical carbon dioxide (sc-CO₂) environment. Photo-Flo (PF) solution and tetrabutylammonium perchlorate (TBAP) were added for the first time into deionized (DI) water-based etchant to serve as degasifying agent for more uniform etching process, and antistatic agent to prevent sidewall etching, respectively. Effect of ohmic contact thickness over etching uniformity was also studied. Finally, copper filling by electroplating under sc-CO₂ environment with no additives was performed to achieve TSV structures with aspect ratio of 1:35 in the short plating time of 2.5 hours.