Encapsulation of the micromachined air-suspended inductors

We have proposed and investigated encapsulation of air-suspended microstructures, especially for micromachined inductors in silicon radio frequency integrated circuits (RF ICs), providing a practical solution for covering up structural weakness to shock/vibration and accommodating package processes. As an encapsulating agent, two materials have been studied; polydimethylsiloxane (PDMS) for examining possible structural deformation when spin-coated, and benzocyclobutene (BCB) for measuring possible electrical performance degradation due to the finite dielectric constant. According to the experiments, no structural deformation has been observed after PDMS is spin-coated. After encapsulated by BCB, the maximum 20% degradation of integrated inductor Q-factor has been observed.