Hybrid Integration of 3D-RF Interconnects on AlGaN/GaN/Si HEMT RF Transistor featuring 2.2W/mm Psat & 41% PAE @28GHz using a Robust and Cost-Effective Chiplet Heterogeneous Bonding Technique

This contribution reports a successfull stacking of an AlGaN/GaN/Si high electron mobility transistor (HEMT) on co-planar-waveguide (CPW) lines fabricated on 200mm Si Trap-Rich substrate. HEMT and CPWs are interconnected with copper pillars (CuPi) using a high-yield chiplet heterogeneous integration process. Thanks to (1) the integration of low insertion loss CuPi interconnects - 0.1dB@28GHz and (2) a careful management of the heat dissipation within the 3D structure, the HEMT transistor features an output power density of 2.2W/mm @10V & a peak PAE of 41%. These RF performances are competitive to other 3D solutions found in the literature. Our industrial grade 3D assembly approach is highly promising for fabricating efficient and cost-effective 3D-RF III-V systems.