Design and Fabrication of a TR Microsystem in Ka-Band With Si-Based 3-D Heterogeneous Integration

This article demonstrated the design and fabrication of a transmitter and receiver (TR) microsystem in Ka-band based on silicon 3-D heterogeneous-integration (3D-HI). To achieve this microsystem, we proposed a novel silicon interposer with bonded metal on the redistribution layer (RDL), which solved the compatibility problem involved in eutectic bond and wirebond processes. A brand new temperature-gradient-free stacking method achieved by printing conductive adhesive bonding technology is also presented, which reduces the stacking temperature while introducing no extra temperature-gradient. Based on these technologies, a four-channels T/R microsystem with a 6-bit phase for both T/R channels, smaller than
$9.5\times 9.8\times 2$
mm, lighter than 0.3 g and working at 33–35 GHz is fabricated, whose receive noise figure is lower than 5.7 dB and the maximum output power exceeds 25 dBm.