In this study, we synthesized a leveler that contained two quaternary ammonium groups attached to hexaethylene glycol. The leveler enabled void- and seam-less Cu filling of the microvia. The convection-dependent adsorption of the leveler was assessed through electrochemical analyses such as linear sweep voltammetry and chronoamperometry on a rotating disk electrode, and the effect of convection on the adsorption of the leveler is interpreted in terms of adsorption diffusion model. In a Koutecky-Levich plot, the enhanced adsorption and inhibition of the leveler at the higher convection was clearly observed with the synthesized leveler. (c) 2017 The Electrochemical Society.