Fabrication of discrete p-n junctions separated by an insulating layer using direct wafer bonding

Three types of fabrication cycle based on the use of direct wafer bonding are developed for making pairs of discrete p-n-junctions separated by an insulating layer. The forward and reverse branches of the I–V characteristics of the resulting diodes are investigated. For all three fabrication cycles, the differential resistance of the forward branch of the discrete p-n-junctions is ∼0.01Ω, the reverse breakdown is ∼400 V, and the width of the aperture region for the back-to-back diodes is 0.22 V. Taken as a whole, these data, along with the high integrated photosensitivity of the diodes, indicate that direct wafer bonding produces no oxide barrier between the p-and n-regions and forms high-quality interfaces.