Mechanical noise induced by acceleration or acoustic disturbances in MEMS microwave inductors

A fully parallel self-assembly fabrication process has been developed previously, where microwave inductors are rotated away from the substrate in order to increase the quality factor and the self-resonant frequency. However, with the devices being up to 500 μm high and freely standing on the semiconductor chip, their mechanical stability needs to be considered. In order to evaluate this issue, a finite element model has been developed. Using this model the displacement due to a mechanical load is determined and variations of electrical characteristics associated with the coil deformation are computed. Comparing the mechanically induced noise power to the thermal noise background level shows that for high signal power levels above approximately 1 mW, mechanical noise can not be neglected and proper care has to be taken with design and packaging in order to minimise this type of noise.