Low-temperature direct bonding of silicon to quartz glass wafer via sequential wet chemical surface activation

We demonstrate a bonding method for combining silicon and quartz glass wafers using a sequential wet chemical surface activation (i.e., SPM→RCAl cleaning). After a multistep post annealing at 200°C, strong bonding with no voids or microcracks was obtained. Based on the detailed surface and bonding interface characterizations, a bonding model was developed to gain insight the low-temperature bonding mechanism. This cost-effective bonding process has great potentials for silicon- and glass-based heterogeneous integrations without requiring vacuum system.