Single sided heating method for chip-to-wafer bonding with submicron Cu/In interconnects

In this research, a single sided heating method is developed to solve the issue of metal oxidation at bottom substrate without antioxidant metal coating in chip-to-wafer bonding. By using optimized bonding parameter, the bonding quality and electrical performance is better than double sided heating in chip-to-wafer bonding. With the help of Cu/In low temperature bonding and single sided heating approach, chip-to-wafer bonding is successfully developed. With the additional annealing process, the bonding duration of single sided heating bonding can be reduced to keep the cost down. Interconnects also maintain good electrical properties after reliability test such as TCT and unbiased HAST. These results prove that the single sided heating method is able to provide good bonding quality and reliability for chip-to-wafer bonding process.