학술논문
Investigation of Co Thin Film as Buffer Layer Applied to Cu/Sn Eutectic Bonding and UBM With Sn, SnCu, and SAC Solders Joints
Document Type
Periodical
Author
Source
IEEE Transactions on Components, Packaging and Manufacturing Technology IEEE Trans. Compon., Packag. Manufact. Technol. Components, Packaging and Manufacturing Technology, IEEE Transactions on. 7(11):1899-1905 Nov, 2017
Subject
Language
ISSN
2156-3950
2156-3985
2156-3985
Abstract
The demand of small-feature-size, high-performance, and dense I/O density applications promotes the development of fine-pitch vertical interconnects for 3-D integration where microbumps are fabricated with Cu through-silicon via and under-bump metallization. Small dimension Cu/Sn bonding has to be developed to address the needs of increasing I/O density and shrinking pitch and size for future applications. For fine-pitch microbumps, it is important to select right UBM and solder materials to obtain lower UBM consumption, which means lower intermetallic compound (IMC) thickness. To find the best binary system material for fine-pitch microbumps with a different annealing temperature and time, we investigate the interfacial reaction and intermetallic compound morphologies of Co UBM with Sn, SnCu, and SAC solders. A thin, uniform, and single-phase IMC between solder and UBM facilitates finer pitch and more reliable microbumps development; the higher activation energies imply longer solder lifetime. Co, as an ultrathin buffer layer (UBL), is also used in Cu/Sn bonding. A comparison between Cu–Sn bonding with and without UBL is conducted. From this study, Co as UBL and UBM is explored and could be applied in semiconductor applications.