Fabrication and measurement of inductor with air bridge crossover structure for monolithic microwave integrated circuit

Abstract

This thesis describes a planar rectangular spiral inductor with air bridge crossover structure which has been required for the development of a high performance GaAs MMIC. The inductor was fabricated by the formations of underpass metal bridge support and bridge metal, where two metallizations were formed by gold plating technique and bridge support was AZ1375 photoresist. The air gap was presumed to be at least 1 um, which could reduce parasitic capacitance at crossover. Design rules obeyed ``lumped conditions`` and the calculation method named ``Expanded Grover Method`` which regards total inductance as a sum of self-inductances and mutual-inductances over all the segments in rectangular inductor. The inductor had been designed 6.45 nH up to 1.5 GHz. Measurements, with preliminary characterization of test jig and compensation of parasitic bonding wire inductance, were made and, from the measurement, the value of the inductance was found to be 5.8 nH $\pm$ 0.6 nH up to at least 2GHz. This difference was thought to come from neglecting the effects of image inductance due to grounding conductor and the photolithography error.