Mechanism Analysis and Cu Interconnection Process Application of Cu Electrochemical Polishing

Abstract

Mechanism of Cu electrochemical polishing (ECP) and application of Cu planarization using Cu ECP were studied. Conventional electrochemical analysis methods were conducted to investigate the mechanism. Diffusion of water acceptors was confirmed by measuring electrolysis currents of water acceptor along the distance from the Cu surface using the scanning electrochemical microscopy system. Mechanism of Cu electrochemical polishing was organized by using all results. Cu ECP was applied for planarization method of RDL and TSV process. At the RDL process, effects of Cu overburden profiles on Cu electrochemical polishing were investigated. Uniform Cu overburden polishing was observed when overburden area was similar at all width patterns. Cu ECP application at the TSV was also conducted. This Cu planarization process was finished in few minutes and current profile was designated to the end point of ECP process. These results were shown the potential that CMP can be alternated to Cu ECP.