Low-Temperature Direct Bonding of Borosilicate, Fused Silica, and Functional Coatings

An experimental study of low-temperature bonding of plasma-treated borosilicate glass and fused silica wafers as well as silicon substrates carrying thin films of silicon dioxide, silicon nitride, silicon oxynitride, and indium tin oxide, respectively, is reported. Plasma process parameters were optimized in order to maximize bond energy. Surface energy measurements were carried out in situ during annealing, helping to understand the kinetics of the bonding process. Power spectral density measurements on debonded wafers support the idea of the strong impact of micro-contact formation on bonding kinetics.