Fabrication and characterization of a microelectromechanical tunable capacitor

A micromechanical tunable capacitor fabricated using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-process has been investigated in this study. The structure of the tunable capacitor consists of a membrane, supported beams, driving and sensing electrodes. The membrane is sustained by the supported beams. The tunable capacitor requires only one wet etching post-process to release the suspended structures. The post-process has the advantages of easy execution and low cost. The tunable capacitor contains a driving part and a sensing part. The sensing part generates a change in capacitance when applying a driving voltage to the driving part. Experimental results show that the tunable capacitor has a capacitance of 1.38 pF, a tuning range of 85% and a Q-factor of 40 at 100 MHz.