Tseng, Y. C.Y. C.TsengLin, Y. S.Y. S.LinHung, Y. C.Y. C.HungC. ROBERT KAO2025-07-072025-07-072025-04-15https://www.scopus.com/record/display.uri?eid=2-s2.0-105007503922&origin=resultslisthttps://scholars.lib.ntu.edu.tw/handle/123456789/730611This study investigates the interfacial reactions among solid copper, tin, and indium. Samples were fabricated by sequentially electroplating 3 μm Cu, 5 μm Sn, and 5 μm In onto a silicon substrate. The results indicate that Sn and In completely react at room temperature, forming β-In3Sn and Y-InSn4, Additionally, a thin and stable Cu-In intermetallic layer, Cu(In, Sn)2, is observed between the Cu substrate and the Y phase. The effectiveness of Cu-to-Cu bonding with In passivation and an Sn diffusion barrier is evaluated. The bonding process was performed via thermal compressive bonding (TCB) at 150°C under 2 MPa for 1 minute. The findings reveal that while the Sn passivation layer does not entirely prevent In diffusion into Cu, it significantly slows down intermetallic formation. This passivation approach enables Cu bonding under mild processing conditions, reducing the need for high temperature and pressure.3D ICCu-to-Cu bondingDiffusion barrierIn passivation layerIntermetallic compound[SDGs]SDG2conference paper10.23919/ICEP-IAAC64884.2025.11003025