A Miniature Electrostatic Actuator with Enhanced Contact Force for a Resistive MEMS Switch

Micromechanical switches are of significant interest for microwave electronics; however, their implementation is hampered by low reliability. Micron-sized actuators generate only a small contact force, which prevents achieving low and stable contact resistance. The contact force is increased by using large and complex-shaped electrodes, but a compact and simple actuator is preferable. This article describes methods for increasing the contact force of an electrostatically actuated MEMS switch. They are demonstrated on a miniature actuator with a movable electrode in the form of a 50-µm-long cantilever. By selecting vertical dimensions, the force can be increased from 10 to 115 μN, exceeding the required threshold of 100 μN with a reserve. The release force also increases and ensures that the switch does not stick. Combining multiple actuators and removing intermediate contact bumps further increases the specific force by at least 50% compared to a single device.