A method is introduced for Cu bottom-up filling at trenches with dimensions similar to those of through silicon via in the presence of three organic additives. The electrodeposition is galvanostatically conducted, and the potential-time curves during the gap-filling and the evolution of deposition profiles according to the deposition time are investigated to clarify the mechanism of the Cu bottom-up filling. The role of each organic additive is examined by electrochemical analyses and the gap-filling profiles with various combinations of organic additives. Based on the results, the gap-filling mechanism regarding the surface coverages of organic additives is suggested. The bottom-up filling of Cu is achieved with the establishment of growing surface at the bottom of trench via the accumulation of accelerator and the strong obstruction of Cu reduction at the side wall and top surface by inhibiting adsorbates. Trenches with 40 mu m depth and widths of 6 or 8 mu m are filled using the suggested mechanism within 15 min. (C) 2013 The Electrochemical Society. All rights reserved.