Contents I. Introduction
Currently, the life time of electrostatically actuated RF microelectromechanical system (MEMS) capacitive switches is primarily limited by dielectric charging, which can cause actuation-voltage shift or, ultimately, stiction [1]–[25]. Experimentally, the dielectric charging phenomenon has been investigated by monitoring shifts in RF transmission characteristics [24], electrostatic and adhesion forces [14], capacitance–voltage characteristics [2]–[6], [8]–[11], [16], and current–voltage characteristics [7], [17], [18], [20], [25] with an increasing level of physical understanding. For example, charge transport was shown to be through the Frenkel–Poole mechanism [11]. Material quality was found to have strong effects on depolarization current [19] and discharging current [20]. Theoretically, a qualitative charging model was proposed [4] and various charge distributions were assumed [6]. A quantitative charging model was developed and validated [21] for charging from the bottom electrode [22] under unipolar control-voltage waveforms of different frequencies, voltages, and duty factors, as well as under different ambient temperatures.
