Advanced 3D Heterogenous Integration (3DHI) for High Frequency RF Applications

3D Heterogeneous integration (3DHI) has become an important technology development effort in the past few years. 3DHI for high frequency RF functions in particular has become key for applications such as 5G and 6G in the commercial world and for many high frequency applications in space and defense. Several factors need to be considered to select a suitable approach for a high performance 3DHI microsystem for RF, including active semiconductor technologies’ performance, materials for interposers, in-plane x-y connectivity, 3D z-connectivity, and the heterogenous integration methods and interfaces. Cost, yield, and the overall mechanical and thermal stability and reliability of the 3D stack are very important as well. An additional challenge in high frequency 3DHI electronic steering arrays (ESAs) is the area available for each array element, which is constrained by λ/2 spacing requirements.