An MCM package process for 24GHz driver amplifier using photosensitive BCB

This paper presents a wafer-level microwave multichip module (MMCM) packaging process for 24GHz driver amplifier using photosensitive-Benzocyclobutene (photo-BCB) of 25 μm. It is developed for multilayer interconnection of monolithic microwave integrated chip (MMIC). A 24 GHz driver amplifier chip is embedded in a wet-etched trench on 4 inch lossy Si wafer and covered with a layer of BCB as dielectrics. Microstrip lines are fabricated with two layers of metal patterns to connect pads on MMIC with the test pads on MCM package in case of excessive loss. The interlayer connection resistance of this metal/BCB interconnection structure is tested with interconnection chain structures through Kelvin resistance measurement. The electrical characteristics of the package are also illustrated. The gain of the amplifier (S
₂₁
) after packaging is more than 22dB from 21GHz to 26 GHz, and the S
₂₁
changes when packaged is less than 2 dB. The return loss S
₁₁
and S
₂₂
is less than -14.1dB and -17.3dB from 21GHz to 26GHz.