Microfabrication of linear translator tuning elements in submillimeter-wave integrated circuits

A micromechanical planar tuning element has been developed and demonstrated in a fully monolithic 620-GHz integrated circuit. It allows for the mechanical variation of the electrical length of a coplanar transmission line tuner and is called a sliding planar backshort (SPB). It consists of a movable patterned rectangular metal plate confined by polyimide flanges along two of its edges to allow guided linear translation along the length of a dielectric-coated coplanar transmission line. Its fabrication involves an application of sacrificial-layer and molding techniques to materials and processes which are compatible with the fabrication of a wide range of submillimeter-wave integrated circuits. This is the first reported micromechanically adjustable tuning element demonstrated at submillimeter wavelengths.