Low temperature full wafer adhesive bonding of structured wafers

In this paper, we present a technology for void free low temperature full wafer adhesive bonding of structured wafers. Benzocyclobutene (BCB) is used as the intermediate bonding material. BCB bonds well with various materials and does not release significant amounts of byproducts during the curing process. Thus void-free bond interfaces can be achieved. Cured BCB coatings have an excellent resistance to a variety of acids, alkalines and solvents and a high transparency for light across the visible spectrum, which makes it a good material for fluidic, optical and packaging applications. We demonstrate the fabrication of fluidic structures and the embedding of protruding surface structures. An important finding is that the pre-cured BCB coatings are extremely deformable and have a liquid-like behaviour during bonding.