Thin Membrane Supported Millimeter Wave Micromachined Filters

This paper presents, the manufacturing of micromachined filters for 38 and 77 GHz using two different type of structures: the first filter structures have as support a 1.5 ?m SiO2/Si3 N4/SiO2 membrane; the second type of filter structures are supported on 2.2 ?m thin GaAs/AlGaAs membrane. These membranes were manufactured using selective dry etching techniques with AlGaAs as an etch-stop layer. On wafer measurements of the filter structures were performed. For the GaAs based micromachined filters, losses less than 1.5 dB at 38 GHz and less than 2 dB at 77 GHz have been obtained