Radiofrequency micro-electromechanical systems (RF MEMS) make it possible to perform switching operations for applications addressing a wide range of frequencies (DC-200 GHz).
Generally speaking, this type of component is designed in coplanar or microstrip technology with a characteristic impedance of 50 or 75 ohms in order to provide optimal guiding of the wave over the entire chip. However, limiting stray effects and keeping the RF adaptation of the MEMS membrane at high frequencies (>20 GHz) imposes technological constraints.
Indeed, the state of the art in RF MEMS presents the mechanical membrane as being:                either entirely made from metal or covered with metal, therefore entirely conductive. In this case, stray capacitances created between the inputs and outputs of the switch often result in a frequency limitation. Furthermore, in a coplanar serial configuration, the RF grounds arranged on the substrate are generally made larger or narrower at the MEMS membrane in order to improve the adaptation, but are not sufficient to guarantee good performance at high frequencies;        or partially metallic. In this case, it is often made up of a conductive line making it possible to convey RF signals and one or several electrodes allowing the activation of the MEMS. Thus, in the majority of cases the RF ground is brought onto the substrate, below the membrane, opposite the activation electrodes. This configuration makes it possible to reach high frequencies, but limits the activation surface and therefore requires designing a larger membrane to guarantee a high contact force (greater than 100 μN) and therefore good reliability. Furthermore, this type of component is always presented in series and may be difficult to implement in a parallel configuration.        
The Applicant proposes to resolve these problems by arranging the RF ground at the MEMS membrane. This configuration has the advantage of being able to keep the RF performance at high frequencies (>50 GHz), preserve an activation force of the MEMS relative to more than 90% of the mechanical surface of the membrane in most cases, improve the power behavior by controlling the circulation of the currents on the membrane and allow simple integration of the component in a parallel configuration without affecting the mechanical properties of the membrane.