Design and manufacturing of wideband buried RF feedthroughs for wafer-level RF MEMS package

This paper reports on the design, manufacturing and RF characterization of a zero-level packaging for RF-MEMS devices based on wafer bonding technology and metal sealing ring. Coplanar buried feedthroughs have been modelled and designed for low loss and wideband RF applications. The CPW line underneath the gold ring has been tapered to compensate the parasitic capacitance of the ring. Compensated and uncompensated packaged CPW lines have been manufactured and measured in the 0-40 GHz frequency band. A significant improvement in terms of RF loss and frequency bandwidth have been obtained thanks to the compensation procedure. Good agreement between experimental and simulated data for the capped and uncapped CPW lines have been obtained showing minimal impact of the package on the RF performance. The RF measurements show an average loss of 0.2 dB up to 30 GHz between packaged and unpackaged CPW lines.