A Micromachined Microwave Switch Fabricated by the Complementary Metal Oxide Semiconductor Post-Process of Etching Silicon Dioxide

In this study, we investigate the fabrication of a micromachined microwave switch using the commercial 0.35 µm double polysilicon four metal (DPFM) complementary metal oxide semiconductor (CMOS) process and the post-process of only one maskless wet etching. The post-process has merits of easy execution and low cost. The post-process uses an etchant (silox vapox III) to etch the silicon dioxide layer to release the suspended structures of the microwave switch. The microwave switch is a capacitive type that is actuated by an electrostatic force. The components of the microwave switch are coplanar waveguide (CPW) transmission lines, a suspended membrane and supported springs. Experimental results show that the driving voltage of the switch is about 17 V. The switch has an insertion loss of -2.5 dB at 50 GHz and an isolation of -15 dB at 50 GHz.