High-Temperature Resistant Intermetallic Compound Joints for Si Chips and Cu Substrates

A thin-film joining method utilizing evaporated films as the joining material was newly developed for power semiconductor die attachment. When the evaporated films are completely transformed into intermetallic compounds (IMCs) with high melting points, the joint can exhibit the required high-temperature strength. In this study, a joint consisting of Cu6Sn5, (Ag,Cu)(3)Sn, and Cu3Sn IMCs was achieved at 573 K after 30 s. Results of nanoindentation tests revealed the hardness and elastic moduli of each IMC. In accelerated tests, a high-temperature strength of at least 15 MPa was shown for 3.6 Ms at 423 K or 500 cycles between 223 K and 403 K. These results suggest that the IMC joint has great potential as a die-attach material.