Substrates and dimension dependence of MEMS inductors

In this work, the effects of metal dimension and substrates on the characteristics of MEMS inductors have been studied. The suspended spiral inductors were fabricated by MEMS technologies with microelectroplating and thick film photolithography. The inductors were suspended by 20 µm over the substrate to reduce the substrate coupling loss and designed a 10 µm thick metal layer to reduce the ohmic loss. We also characterized the properties of inductors according to the substrates, the size of gap between the inductor metal lines and the width of the inductor metal lines. The measured quality factor of inductors fabricated on a silicon substrate was over 20 at 2 GHz. The inductors were also fabricated and measured on various substrates such as high resistive silicon, glass and quartz wafers. The quality factor of the inductor fabricated on the glass substrate was almost 30 at 4 GHz and that of the inductor fabricated on the quartz wafer was over 40 at the same frequency region. Substrate resistance and the dimension of metal are factors important to the inductor performance