Interface Properties of Thin Film Bonding by Low Melting Point Metal for MEMS devices

Low temperature metal bonding is promising for assembling micro devices because the interface can easily achieve high mechanical reliability by the formation of metallurgical and electronically high conductive interfaces. For gaining high strength of micro joints with low temperature process, vacuum deposited low melting point metal (Sn_xln_1-x) thin films were applied to solid-liquid diffusion bonding of copper. The effects of Sn content on the growth of reaction layer and on the shear strength were investigated. It was found that the sufficient initial Sn supply was important to achieve high strength interface characteristics to enhance solid-liquid diffusion.