Integration of an RF MEMS resonator with a bulk CMOS process using a low-temperature and dry-release fabrication method

In this paper, a novel low-temperature post-CMOS process to fabricate a microelectromechanical (MEMS) bridge resonator has been developed. The integration of the MEMS resonator with the bulk N-well CMOS process is demonstrated experimentally. The sub-micron gap between the resonator beam and electrodes is defined by the sacrificial polymeric layer thickness and dry released in O2 plasma. The resonator beam is fabricated using single crystal silicon and released using isotropic silicon etch. The effect of floating driving electrodes on the resonator operation has been analyzed and modeled. S-parameter measurement is conducted. Results show a resonant frequency of 64.56 MHz with a quality factor of 60 under atmospheric pressure for a resonator device with the length of 30 νm, width of 4 νm and thickness of 2 νm operating at second resonant mode.