An all-metal RF-MEMS switch with large displacement and potential mechanical creep reduction

This paper presents the design and measurement of a high isolation gap RF MEMS (Micro-Electro-Mechanical System) metal-contact switch. The main idea is to have a high off-state separation gap by using a see-saw system. In the proposed device, a soft-metal beam can be used for mechanical operation since mechanical anchors are not solicited during movement. The switch toggles on either side of a pivot thus reducing dramatically the effect of creep. The obtained off-state separation gap is 1.8 μm and the corresponding capacitance is only 6 fF. Beam geometry optimisation allowed reaching 240 μN contact force with 15 Volts bias and a contact resistance contact less than 2 Ω. The switch has been held in the down state for 15 minutes twice then for 2.5 hours without any measurable reduction of the up state capacitance, demonstrating the immunity to creep of the device.