Levelers exhibiting high microvia-filling power and wide operating-concentration ranges are required for the development of additives in copper super-conformal electroplating. In this study, a novel structure based on triphenylmethane (TPM-1) was synthesized and investigated as a leveler for microvia-filling electroplating. The galvanostatic measurements and cyclic voltammetry stripping experiments show that TPM-1 is a stronger inhibitor than Janus Green B for copper ion reduction and is essential in creating convection-dependent adsorption behavior. Copper electroplating experiments were conducted, and TPM-1 showed superior microvia-filling performance at a relatively wide concentration range. (C) 2019 The Electrochemical Society.