Microvia filling by copper electroplating using diazine black as a leveler

An organic additive, Diazine Black (DB), was employed as a leveler for microvia filling using copper electroplating. DB is a derivative of Janus Green B (JGB), which is a common leveler used for copper fill of submicron or micron circuit metallization in electronic products. This study determined the optimal DB concentration for achieving the best filling performance. The electrochemical behavior of DB and its interaction with other additives, such as a suppressor and an accelerator were characterized using galvanostatic measurements. These electrochemical analyses helped explaining the filling mechanism of the plating formula containing the DB. Various surface morphologies and the crystalline orientation of the plated copper films caused by different DB concentrations were characterized by a scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The corresponding chemical activity of the surface atoms of the plated copper films caused by different DB concentrations was characterized using a test of etching rate.