A study of electrochemically deposited copper on PVD copper and TiN using a Cu-EDTA complexed bath

摘要

This paper discusses the nucleation and growth of electrochemically deposited copper from a copper-EDTA complexed bath. Substrate features studied included non-patterned and patterned trenches of PVD Cu and TiN on a silicon wafer. On TiN, the system exhibited two-dimensional nucleation followed by three-dimensional growth, which is classified as the Stranski-Krastanov mechanism. Theoretical nucleation and growth models were successfully applied to the current transient and were consistent with microscopic observations. On PVD copper, growth was layer-by-layer. Near complete trench fill was obtained on TiN while deposition on PVD Cu resulted in large voids due to mass-transport limitations.