The reduction of filling time is one of the current challenges in through silicon via (TSV) filling by Cu electrodeposition. Electrodeposition rate can be increased with higher current density; however, it can result in the formation of voids due to a negative shift in the potential, which can deteriorate the effect of organic additives for TSV filling. In this work, we introduce thiourea to increase the inhibition of additives on the side walls of TSV against Cu deposition. It was found that thiourea increases the inhibition effect of the suppressor, which leads to the reduction of filling time by half. (C) 2018 The Electrochemical Society.