In order to increase the lifetime of the series contact MEMS switch with dielectric bridge

an isotropic undercutting process for forming the upper control electrodes and contact bar under the bridge is introduced. In comparison with the regular process

the introduced method can enhance the planeness of the bridge

avoid the problem of stress concentration

and thus improve the mechanical reliability of the switch. As a result

the yield rate of the switch increases from 10% up to 95%

and the lifetime is improved from 1

000 cycles up to 25

000

000 cycles. Under the actuation voltage of 23.3V

the insertion loss is 0.55dB＠DC-10GHz

and the isolation is 53.2dB＠DC-10GHz.