A Novel Integrated RF MEMS Switch

Microwave switch matrices are essential components in wireless communication systems. Compared with conventional solid switches such as PIN diode and CMOS, radio-frequency (RF) microelectromechanical systems (MEMS) switch is a good candidate with a great potential to offer miniature, high isolation, low insertion loss and low power consumption. Despite these benefits, RF MEMS switches are not yet seen in commercial products because of reliability issues, limits in signal power handling and questions in packaging and integration.The paper presents a novel concept for 3D RF MEMS switches based on integrating MEMS actuators with waveguide structures, which are fabricated by independent processing and subsequent bonding together of a MEMS substrate in alignment with an RF substrate. A capacitive shunt switch is designed on the basis of the micro-platform technology. The switch consists of switch structure in low resistive single crystal silicon (SCS), both pull-up actuation electrode on the glass lid and pull-down actuation electrode on the high resistivity silicon (HRS) substrate. The impact of the insertion of the oxide layer between the metal circuits and HRS is analysized. It is demonstrated that the introduction of thin undoped polysilicon layer between the oxide layer and HRS could be helpful in alleviating the population of surface charges at the SiO₂/Si interface, resulting in the accomplishment of DC isolation without the degradation of RF loss charactristics. The low spring-constant folded-serpentine beams are adopted to low down the driving volt(?). The spring constant herein is deduced by the energy method for good accuracy. Both static and dynamic analyses including pull-in voltage, quality factor, self-actuation and power handling are performed to evaluate the performance parameters of the switch structure. The initial gaps between the...