Multilayer Micromachining Technology for the Fabrication of Ka Band Filters

This paper presents the manufacturing and testing of a new type of compact and low loss 4th order Ka-band filter in multilayer micromachining technology. The filter is based on λ/2 TEM Si membrane resonators placed inside shielding cavities and short-circuited at both anchored ends. The membranes and the cavities are realized by DRIE on SOI wafers and are metalized by gold electroplating. The filter is realized by stacking and bonding six silicon layers for a reduced footprint and area occupation. The RF measurements are very promising, showing insertion loss better than 3dB and Q factors above 500 in Ka-band. Shear tests demonstrated good adhesion of bonded layers and preliminary thermal and mechanical shock test indicated the filter robustness.