VO₂-based MEMS mirrors

This paper reports the integration of vanadium dioxide (VO₂) thin films in a microelectromechanical systems (MEMS) mirror device, where the actuation is mainly due to the solid-solid phase transition of VO₂. The fabrication process described in this paper provides the details that will enable the integration of VO₂ thin films at any step during the fabrication of rather complex MEMS devices. The present VO₂-based MEMS mirror device is operated electro-thermally through integrated resistive heaters, and its behavior is characterized across the phase transition of VO₂, which occurs at a temperature of 68 °C and spans about 10 °C. The maximum vertical displacement of the mirror platform is 75 μm and it occurs for an input voltage of 1.1 V. This translates to an average power consumption of 6.5 mW per mirror actuator and a total power consumption of 26.1 mW for the entire device. The studies included in this paper are key for future device improvements and further development of MEMS mirror actuation technology, which could include the use of the hysteresis of VO₂ for programming tilting angles in MEMS mirrors.