Fine-Feature Cu/In Interconnect Bonding Using Single Sided Heating and Chip-to-Wafer Bonding Technology

A submicron-thick Cu/In bonding by using single sided heating approach has been successfully demonstrated on chip-to-wafer-level without antioxidant metal coating. The single sided heating approach can successfully prevent oxidation of Cu metal on the wafer during bonding. As compared with double sided heating method, a lower specific contact resistance can be obtained in single sided heating method. In addition, post-bonding annealing can further improve the bonding quality. Excellent electrical performances of reliability tests show a great potential for future highly dense interconnect.