Structural changes from high-density electric currents were examined in a eutectic In-Sn/Cu interconnect. Under electrical loading, Sn and In migrated in opposite directions, creating a partition of the Sn- and In-rich phases between the anode and the cathode. At the anode, a net gain of Sn atoms resulted in the formation of massive, columnar hillocks on the surface, but a net loss of In led to dissolution and disappearance of the In-rich intermetallic layer. At the cathode, the exodus of Sn left valleys adjacent to the In-rich regions on the surface, while the amount of the In-rich phase grew, due to the net influx of In at the expense of the In-rich intermetallic layer.
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ACKNOWLEDGEMENTS
Support for this study was provided by the Chinese Natural Sciences Foundation, grant # 50228101, and the National Basic Research Program of China, grant # 2004CB619306. The authors also owe special thanks to Dr. Warke, Q.L. Yang and others in the Microelectronics Laboratory at IMR for their assistance.
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Daghfal, J.P., Shang, J.K. Current-Induced Phase Partitioning in Eutectic Indium-Tin Pb-Free Solder Interconnect. J. Electron. Mater. 36, 1372–1377 (2007). https://doi.org/10.1007/s11664-007-0206-5
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DOI: https://doi.org/10.1007/s11664-007-0206-5