Impact of Bath Stability on Electroplated Cu for TSVs in a Controlled Environment

This study addresses the impact of bath stability on electroplated copper for through-silicon via (TSV) in a controlled manufacturing environment. Microstructure, impurities, and other properties of the copper produced were characterized using an array of techniques, including electron backscatter diffraction analysis, focused ion beam–secondary electron microscope, and time of flight–secondary ion mass spectrometry. Chemical analyses of the plating baths throughout their lives indicates that the process can be controlled. Overall, a manufacturing process was demonstrated that can create high-quality, TSV Cu fill interconnects for 3-D IC over the life of the bath. The process has enabled further development work at State University of New York Polytechnic Institute for downstream processes such as chemical mechanical planarization and Cu-Cu bonding.