A New Temperature-Tolerant RF MEMS Switch Structure Design and Fabrication for Ka-Band Applications

In this paper, the design and fabrication of a new radio frequency (RF) microelectromechanical system (MEMS) switch structure is presented. This RF MEMS switch is developed to get the minimum permanent deformation on the microbridge after 200 °C thermal treatment. The residual stress-based buckling on the MEMS bridge is simulated for 5-40-MPa/μm stress gradient (Aσ) with 5-MPa/μm steps. The temperature-dependent extension and deformation on the MEMS bridge are modeled up to 270 °C. The temperature-dependent permanent deformation on the MEMS bridge is reduced by optimizing the dimensions of the bridge. The electromechanical and electromagnetic simulations are carried out to find the actuation voltage and the RF performance at Ka-band. The actuation voltage is measured as 22 and 25 V before and after 200 °C thermal treatment for 2-μm air gap (g0). The RF performance of the switch is measured before and after 200 °C thermal treatment to observe the temperature effect on the MEMS bridge. The persistent insertion loss (<;0.35 dB) and the isolation (<;-20 dB at 28-40 GHz) are measured before and after thermal treatment. The RF MEMS switch is fabricated on quartz wafer using an in-house surface micromachining process with an amorphous silicon sacrificial layer structure.