Fabrication of a superconducting MEM shunt switch for RF applications

We have developed a fabrication process for a superconducting MicroElectroMechanical (MEM) shunt switch. The design of the switch has been optimized using Sonnet simulations. The switch consists of a YBa₂Cu₃O₇ Coplanar Waveguide (CPW) transmission line with a gold membrane bridge anchored at the ground planes and suspended above an area of the center conductor covered with BaTiO₃. Under an applied electric field this membrane bridge actuates downwards and shunts the RF signal to ground. The membrane returns to its original shape when the electric field is removed. In the up position the device exhibits an s₂₁ insertion loss of less than 0.25 dB from dc through 900 MHz (most of which is due to radiated loss). In the down position the s₂₁ loss in the same frequency range is greater than 30 dB.