부산대학교 도서관

Low-temperature (170$^{\circ}{\rm C}$) Cu/In wafer-level and chip-level bonding for good thermal budget has been successfully developed for 3-D integration applications. For the well-bonded interconnect, ${\rm Cu}_{2}{\rm In}$ and ${\rm Cu}_{7}{\rm In}_{3}$ phases with high melting temperature of 388.3$^{\circ}{\rm C}$ and 632.2 $^{\circ}{\rm C}$ can be formed, indicating high thermal stability. In addition, stable low specific contact resistance of bonded interfaces can be achieved with the values of approximately $0.3\times 10^{-8}~\Omega\hbox{-}{\rm cm}^{2}$. In addition to exceptional electrical characteristics, the results of electrical reliability assessments including current stressing, temperature cycling, and unbiased HAST show excellent stability of Cu/In bonds without obvious deterioration. The low-temperature Cu/In bonding technology presents good bond quality and electrical performance, and possesses a great potential for future applications of 3-D interconnects.