Miniature RF MEMS metal-contact switches for DC-20 GHz applications

This paper presents the design and measurements of a miniature RF MEMS (Micro-Electro-Mechanical System) metal-contact switch. The dimensions (25×24 × 1.6 μm) and shape of the beam and actuation pad have been optimized to result in a 12-25 μN contact force at 52-60 V actuation, with a corresponding restoring force of 15 μN. Measured S-parameters on a single switch show an up-state capacitance of 5 fF and a 13-14 Ω contact resistance for a Au-Ru contact under an actuation voltage of 55 V. In order to reduce the effective switch resistance, 10 miniature RF MEMS switches have been placed in parallel and result in an up-state capacitance of 30 fF and a switch resistance of 1.4 Ω. The measured switching time is 2.2 μs and the release time is <;1 μs. The switch is robust to stress effects (residual and stress gradients) which increases its yield on large wafers. To our knowledge, this is the first demonstration of a miniature RF-MEMS metal-contact switch and with an excellent figure-of-merit (f_c=1/(2.π.R_on.C_u)=3.8 THz).