Wafer-to-wafer selective flip-chip transfer by sticky silicone bonding and laser debonding for rapid and easy integration test

Abstract

Wafer-bonding-based integration can be rapidly and easily tested between different types of devices by wafer-to-wafer flip-chip transfer technology described in this paper. Devices to be tested (e.g. MEMS) on a support wafer are bonded and electrically connected with a target wafer (e.g. LSI) using sticky silicone bumps, and then any of the devices are selectively debonded from the support wafer by backside laser irradiation. After transferred, the device is temporary sealed with a silicone ring, and underfill polymer can be used for permanent bonding. Because silicone bonding is made just by physical contact at room temperature, and the elasticity of silicone absorbs mismatch in thermal expansion, integration between different materials of wafer is possible. For practical demonstration, LiNbO3-based SAW resonators were transferred to an LSI wafer.