A leveler is one of the key additives for the defect-free filling of Through Silicon Via. The convection dependent behavior of a leveler is required to achieve successful gap-filling of Cu. Levelers occasionally contain charged functional groups and the counter anions. The charged functional groups obviously determine the characteristics of the leveler, and counter anions also influence the electrochemical behavior and Cu gap-filling. In this study, we synthesize levelers that have two quaternary ammoniums and different counter anions. The electrochemical behavior of the synthesized levelers and the effect of the counter anions on Cu gap-filling are described. (C) 2016 The Electrochemical Society. All rights reserved.