The Defense Advanced Research Projects Agency (DARPA) Microsystems Technology Office (MTO) is requesting information to guide the establishment of a domestic research and development (R&D) center for fabrication of three-dimensional heterogeneously integrated (3DHI) microsystems. Phase 0 of the DARPA Next-Generation Microsystems Manufacturing (NGMM) program is currently analyzing and determining the software tools, hardware tools, process modules, electronic design automation (EDA) tools, and packaging and assembly tools needed to manufacture representative 3DHI microsystems. The next phases of the program (Phase 1 and 2) seek to create an operational R&D capability for advanced heterogeneously interconnected components, for stakeholders in academia, small and medium businesses, defense and commercial companies, and government organizations. Technologies involved include, but are not limited to, compound semiconductors, photonics, and microelectromechanical systems (MEMS), and extend into the power, analog, and radio frequency (RF) domains, in addition to digital logic and memory. The end result of the program will be an open-access R&D center accessible by the stakeholders to holistically address the design, packaging, assembly, and testing of 3DHI prototypes.
In Phase 1, the NGMM program will establish a center, at an existing facility, with stateof-the-art packaging, assembly, and testing of either digital, RF, photonic, or power devices. DARPA will fund the labor, equipment, materials, and supplies necessary for upgrading and/or modifying existing hardware tools, software tools, and EDA tools to perform 3DHI (R&D). Phase 1 will also focus on developing baseline process modules, along with an initial pre-commercial 3DHI pilot-line capability (stable packaging and assembly process) and associated 3D assembly design kit (3D-ADK). Phase 2 will further optimize the 3DHI process modules, add R&D efforts to increase packaging automation, and implement the operational access model for the center, which will commence collaborative research efforts with external microelectronics organizations. Upon completion of Phase 2, it is anticipated that oversight of the NGMM center will transfer from DARPA to another government agency, and that continued process maturation will develop low-volume production capability of innovative 3DHI microsystems. Additionally, this center will enable technology transfer of equipment, processes, and designs that are developed within NGMM to support fabrication of these microsystems at external commercial and defense packaging facilities.
The next major wave of microelectronics innovation is expected to come from the ability to integrate heterogeneous materials, devices, and circuits through advanced packaging, producing a tightly-coupled system that extends into the third dimension with performance that exceeds what is available from today’s monolithic approach. Industry leaders currently use 3D integration of modestly dissimilar silicon digital technologies for a narrow range of commercial products, from stacked dynamic random-access memory (DRAM) to complementary metal-oxide-semiconductor (CMOS) imagers to high-performance computing. Today’s mature integration techniques, even those often referred to as 3DHI, focus primarily on low-power leading-edge CMOS, legacy CMOS, and silicon-based memory. However, the opportunity to broadly impact defense systems relies on expanding the types of microelectronics that can be integrated and assembled. Further, advancing digital integration requires increasing interconnect densities well beyond today’s state-ofthe-art. DARPA’s expansion to heterogeneous integration also includes compound semiconductors for RF and photonics for interconnect, novel memory devices for computing, and wide-bandgap and ultra-wide bandgap semiconductors for power electronics.
Presently, the U.S. has no open-access center with capacity for sustained 3DHI research and development. With very few exceptions, U.S. companies engaged in 3DHI research rely upon offshore facilities, e.g., TSMC (Taiwan) and Interuniversity Microelectronics Centre (IMEC, Belgium). An open-access domestic center for 3DHI R&D would result in a more expansive wave of innovation, would promote shared learning, and would ensure that start-ups, academia, and the defense industrial base could engage in 3DHI R&D for low-volume products.
The NGMM program aims to emphasize 3DHI microsystems that incorporate different material systems in the same package, such as photonics for interconnects, novel memory devices for computing, wide-bandgap and ultra-wide bandgap semiconductors for power electronics, and additively manufactured passive components. In this RFI, 3DHI refers to the stacking of separately fabricated components from different material systems, within a single package, to produce a microsystem that provides revolutionary improvements in functionality and performance. Specifically, these microsystems will integrate disparate wafers or chips into vertically stacked architectures.
