Formation mechanism and reliability of preferred growth full Cu6Sn5 intermetallic compound interconnect on (011) Cu single-crystal substrate

The preferred growth full intermetallic compound (IMC) interconnect was fabricated using the current driven bonding (CDB) method. The morphology, orientation and growth mechanism of preferred growth eta-Cu6Sn5 grains on (011) Cu single-crystal substrate under current stressing were investigated. Four growth directions of slantwise eta-Cu6Sn5 grains that have an angle of 60 degrees with the current stressing direction were identified. The orientation relationships between the preferred growth eta-Cu6Sn5 grains and (011) Cu single-crystal substrate were {11 (2) over bar0}(eta) parallel to{111}(Cu) and 0001 (eta) parallel to 011 (Cu). The eta-Cu6Sn5 grains in the same growth direction merged and continued coarsening undergoing the current stressing, while the eta-Cu6Sn5 grains in different growth directions could not merge due to the smaller contacting grain boundary area. Furthermore, the current stressing induced the <0001>(eta) growing directions of slantwise eta-Cu6Sn5 grains to a smaller angle with the current stressing direction. The preferred growth full IMC interconnect had a superior electromigration resistance. No voids or cracks were observed in the preferred growth full IMC interconnects even after current stressing at 150 degrees C for 500 h. The present work is expected to provide guidance for the application in high temperature packaging technology of the third-generation semiconductor devices.