Low-cost Mid-wave Infrared Focal-Plane Array (FPA) Fabrication through Direct-bond Interconnection

SBIR topic DON27BZ02-NV011 (U.S. Department of Defense – Navy), Phase I and II. Open to U.S. small businesses. Opens: December 2, 2026. Closes: January 6, 2027. Electro-Optic and Infrared (EO/IR) sensors are used in a wide variety of applications, such as navigation, wide-area surveillance, and targeting. Operating in the visible and near-IR bands, EO sensors are available with small pixels and in large arrays at low cost, because the Si-detector wafer and Si-ROIC wafer can be 3D-integrated directly through wafer-to-wafer bonding with high yield at high volume based on material and complementary metal-oxide-semiconductor (CMOS)-process compatibility. By contrast, sensors operating in the MWIR employ III-V detector materials, which are not CMOS-process compatible, while III-V epi-layer detectors cannot be epitaxially grown directly on Si, as required to produce the crystalline order of high-quality detectors [Refs 1-2]. Instead, the III-V detector epi-layer is grown on a lattice-compatible substrate wafer, which is then flip-chip bonded to a Si-ROIC through a dense array of sub-pixel indium bumps placed on each wafer, followed by detector-substrate removal. The technically demanding process of depositing, aligning, and compressing the dense arrays of indium bumps on detector and ROIC die, results in a labor-intensive, inefficient, low-yield process for IR FPA fabrication, which greatly increases cost. In recent years, 3D-heterogeneous integration has enabled a single integrated chip of greater overall functionality to be realized at reduced cost by assembling multiple smaller chips, each having unique functionality, material, node size, and/or foundry origin. Direct-bond interconnection (DBI) [Refs 3-5] is a 3D-heterogeneous integration technique that can potentially enable low-cost MWIR FPA fabrication. In principle, DBI should enable very large format FPAs with small pixels to be fabricated, as the process is largely independent of wafer and pixel size, in…