High-strength Si wafer bonding by self-regulated eutectic reaction with pure Zn

A method for bonding Si wafers has been developed using pure Zn as a solder. This process can be carried out under atmospheric pressure without metallization. The resulting shear strength of the bonding exceeds 50 MPa, significantly higher than the typical strength of conventional Au-20Sn solders. The superior results are ascribed to a uniform and void-free interface created by a self-regulated Si-Zn eutectic reaction. Our cost-efficient wafer bonding method may have a wide range of applications in Si-based devices.