Die-to-Die Adhesive Bonding Procedure for Evanescently-Coupled Photonic Devices

Recently demonstrated evanescent hybrid III-V/Si lasers are mostly based on molecular bonding of a III-V die on an SOI photonic wafer. This procedure requires ultra-clean and smooth bonding surfaces and might be difficult to implement in an industry-scale fabrication process. As an alternative, we present a die-to-die adhesive bonding procedure, using a DVS-BCB polymer. We achieved less than 100 nm-thick bonding layers that enable evanescent coupling between III-V and silicon. The process shows good robustness and bonding strength, with a break-down shear stress of 2 MPa. The process can be scaled-up to a multiple die-to-wafer bonding procedure.