Direct bonding between InP substrate and magnetooptic waveguides

Wafer direct bonding was demonstrated between InP and magnetooptic materials. The effects of chemical treatment of two wafers before placing them into contact were investigated in order to enhance the durability of the bonded wafers through the various device fabrication processes. Phosphoric acid etching at a low temperature proved to be the most suitable treatment for the bonding between InP and gadolinium gallium garnet Gd₃Ga₅O₁₂. In the case of this treatment, the bonding was studied between a planar InP substrate and magnetooptic waveguides on the garnet films.