Low-actuation voltage RF MEMS shunt switch with cold switching lifetime of seven billion cycles

This paper investigates the performance and lifetime of a metal-to-metal shunt RF MEMS switch fabricated on an SI-GaAs substrate. The switch is a shunt bridge design that is compatible with standard microelectronic processing techniques. The RF performance of the switch includes actuation voltages of less than 15 V, isolation better than 20 dB from 0.25 to 40 GHz, and switching speeds of less than 22 μs. Varying the geometry of the switch affects both switching voltage and reliability, and the tradeoffs are discussed. We have developed a cold switching test method to identify the root cause of sticking as a failure mechanism. The switch structure includes "separation posts" that eliminate sticking failure and has demonstrated lifetimes as high as 7×10⁹ cold switching cycles. These results show that good reliability is possible with a metal-to-metal RF MEMS switch operated with a low actuation voltage.