Approaches to Heterogeneous Integration for Millimeter-Wave Applications

Introduction . Enhanced performance of electronic systems can be achieved by heterogeneous integration of different semiconductor technologies. The benefits of heterogeneous integration become obvious when close connections between the devices are provided. The development of integration approaches, enabling functionality and improved performance, appears a relevant task for modern microwave microelectronics. Aim . Review of state-of-the-art and promising heterogeneous integration concepts and techniques in microwave microelectronics. Materials and methods . Eight integration approaches that ensure the connection of devices based on different semiconductor technologies for microwave frequencies are considered: monolithic heterogeneous integration, wafer bonding, micro-transfer printing, embedded chip assembly, print additive manufacturing, wire bonding, flip-chip, and hotvia. The integration approaches are analyzed in terms of their implementation specifics, advantages and disadvantages. Results . Monolithic heterogeneous integration and wafer bonding, as well as micro-transfer printing, despite the minimum interconnections, have a number of fundamental limitations. These limitations are related to the compatibility of various semiconductor technologies and the necessity of high technological capabilities. The technology of embedded chip assembly enables the variability of implementation techniques, which makes it possible to provide unique characteristics, e.g., due to the integration of magnetic materials. However, this approach is associated with a high complexity of integration technological processes. Flip-chip integration ensures minimal interconnect losses due to bump miniaturization. Hot-via, as a modification of flip-chip, provides for a better compatibility with microstrip type circuitry. Their further improvement and mass application largely depends on the development of technologies for the formation of low-pitch interconnections. Conclusion. The development of close integration approaches in microwave microelectronics is proceeding both in the monolithic direction, i.e., monolithic heterogeneous integration wafer bonding, as well as in the quasi-monolithic direction, i.e., micro-transfer printing, embedded chip assembly, print additive manufacturing, flip-chip, and hot-via. The conducted comparative analysis of the presented methods has practical application.