Polymide Based GaAs Micromachined Millimeter Wave Structures

This paper presents the manufacturing of high performance millimeter wave lumped elements on polyimide membranes obtained by micromachining of SI GaAs. The microwave performances of the devices are compared with those obtained for similar structures manufactured on SiO2/Si3N4/SiO2 membranes on silicon micromachined substrates, as well as with perfomances of similar devices manufactured on bulk GaAs and high resistivity silicon. S parameters analysis and the computed lumped equivalent circuit emphasize the substantial decreasing of the parasitic capacitances and, as a result, the outstanding improvement of the resonant frequency of membrane supported inductors.Polyimide membranes manufactured on GaAs substrate have prooved to be a very good support for millimeter wave cicuit elements both from mechanical as well as from electrical point of view.