Bonding strength enhancement by Ag–Zn–Cu intermetallic compounds and microscale tapers array fabricated by femtosecond laser.

In this study, a highly reliable and effective method for copper bonding using femtosecond laser-fabricated microscale tapers array and Ag–Zn–Cu intermetallic compounds as assistants is proposed. By the growth of intermetallic compounds among the microscale tapers array, the copper interfaces were firmly sintered. The cross section after shearing test was marked for analysis of sintering quality. Also, the shearing strength of interconnected copper interfaces under different bonding temperature, and holding times was investigated. The results show that the shearing strength can reach up to 120.1 MPa under 300 °C bonding temperature and 30 min holding time. According to the interconnected cross section and shearing strength test, the mechanism of increased shearing strength is explained. The experimental results show that the shearing strength of interconnected interface is greatly enhanced by the increase of contact area caused by microscale tapers array and the mechanical locking caused by the growth of intermetallic compounds. More possibilities could be provided by this technology in the field of electronic packaging interconnection and three-dimensional integrated circuits. [ABSTRACT FROM AUTHOR]