Low-temperature sealing for optical microsystem packages using Au-Au surface activated bonding in atmospheric pressure environment

For chip-size packaging of optical microsystems, surface activated bonding (SAB) method is one attractive candidate because of its low-temperature process. However, most of packaging processes with SAB method have been performed under ultra-high vacuum conditions, because it needs maintaining the activated surface during bonding process. In this study, we demonstrate low-temperature hermetic sealing at atmospheric pressure using Au-Au SAB, because Au is not oxidized and its activated surface can be kept for several tens of minutes in ambient air. Strong bonding force and hermeticity were experimentally confirmed by low-temperature SAB bonding (150°C).