Design and micro-fabrication of high-speed micro-switches

Electromechanical vibration suppression systems reveal the necessity for a high-speed micro-switch. High-speed micro-switches are also required for devices such as wave-phase shifters for phased-array antennas, wireless telecommunications, and other Radio-Frequency (RF) signal devices. These devices not only require a high switching speed, but also low energy consumption and high power handling. Standard Integrated Circuit (IC) switches or solid state relays (SSR's) can meet the switching time requirement. However, these switches are not able to handle the voltage required on vibration suppression systems. The present work analysed different micro-switch configurations and focused attention on comb drivers or lateral actuators. Advantages such as a single mask fabrication procedure and its ability to tune the on and off time of the micro-switch were fully analysed, resulting in a high-speed micro-switch actuated by a low voltage 30V. A detailed micro-manufacturing procedure involving a novel nickel electrodeposition on silicon without a seed layer was employed to fabricate these micro-switches. In addition, an acetone drying procedure was implemented to avoid stiction successfully realising structure with a 3:1 height aspect ratio. A computational model was developed to design micro-switches with a switching on time below 20 microseconds. Experiments with fabricated devices showed excellent agreement between model predictions and micro-switch motion.