100 nm vias were completely filled with copper for interconnect applications using an electrolyte in the presence of polyethylene glycols (PEG) and a hybrid-mode additive, benzotriazole (BTA). Electrochemical analyses indicated that BTA with a higher concentration inhibited the copper deposition rate, whereas BTA with a lower concentration accelerated the copper deposition rate. This electrolyte thus generated an enhanced deposition gradient within a gap because the PEG molecules and the high concentration of BTA, adsorbed at the opening of the gap, inhibited the deposition. Meanwhile, a little BTA diffused into the inner part of the gap and thus accelerated the deposition of copper. Therefore, this two-component (PEG and BTA) additive electrolyte had the capacity of a three-additive bath (accelerators, suppressors, and levelers).