Direct Bonding Energy in Anhydrous Atmosphere.

Direct bonding energy is an important parameter for direct bonding applications as well as for mechanism elaboration. Thanks to its simplicity as well as for its simple result interpretation, double cantilever beam (DCB) under prescribed displacement is the most used technique to measure the direct bonding energy. But, as shown also in this study, measurement of Si/SiO2 or SiO2/SiO2 direct bonding in standard humid atmosphere is greatly impacted by water stress corrosion. To prevent this effect, bonding energies have been evaluated under anhydrous atmosphere with less than 0.2ppm of water in nitrogen. After the setup and methodology description of the bonding energy measurement without stress corrosion influence, the global classical Si/SiO2 and SiO2/SiO2 direct wafer bonding energy curves versus post-bonding annealing temperature are revisited. Moreover, by using various surface treatments prior to bonding, the bonding energy behavior according to post-bonding annealing can drastically change as for example with plasma surface activation treatment. But in contrary, silicon-silicon hydrophobic bonding energy seems not impacted by the measurement atmosphere. Such results will also be presented and discussed.