Soft Surface Activated Bonding of Hydrophobic Silicon Substrates

Surface Activated Bonding (SAB) is interesting for strong silicon to silicon bonding at room temperature without any annealing needed, afterwards. This technique has been recognized by the scientific community for more than two decades now and was used for numerous reviewed applications. Although it is a well-known technique, the activation step, in particular, is scarcely documented. This paper offers insights about the impact of soft activation parameters on the amorphous region at the bonding interface. In addition, the adherence energy of hydrophobic silicon after SAB bonding is quantified, to better understand bonding mechanisms. Soft activation parameters on hydrophobic silicon substrates yield exceptionally thin bonding interfaces with acceptable bonding energy at room temperature. According to cross-sectional Transmission Electron Microscopy imaging, a 0.53 nm thick amorphous silicon interface was achieved with an adherence energy of 1337 ± 137 J/m² measured by the Double Cantilever Beam method.