Dielectric fluid immersed MEMS tunable capacitors

Abstract

Enhancement of MEMS tunable capacitors using dielectric fluids is reported. Micromachined tunable capacitors were tested and characterized in air and in mineral oil with a relative permittivity (/spl epsi//sub r/) of 2.29. In oil the capacitors exhibit a factor of 2.2 to 2.29 increase in the initial capacitance as well as the achievable tuning range. The theoretical electrical and mechanical performance enhancements have been verified for capacitors with self-resonant frequencies of 18.3GHz in air. The high frequency testing device exhibited a capacitance of 344fF at 5GHz with a Q-factor of 72 in air, and a capacitance of 799fF with a Q-factor of 40 in oil. In addition, the devices immersed in oil have increased, tunable damping and a significantly higher breakdown voltage.