Design, fabrication and characterization of RF MEMS switches with robust contact

Abstract

This paper presents the fabrication and characterization of a mechanical microswitch structures for the out-of-the plane displacements. The mobile electrode is connected to the anchors through several rectangular hinges fabricated in different geometrical dimensions. The mechanical response of investigated switch structures depends on the number of hinges and their geometrical dimensions. The geometrical dimensions of hinges have a strong influence on the stiffness of mobile electrode. The scope of research work is to analyze the mechanical behavior microswitch structures in order to improve the accuracy in response and to increase the microdevice lifetime. The mechanical switch structures analyzed in this paper are fabricated by electron beam evaporation from aluminum, due to its adequate mechanical and electrical properties. Experimental tests are performed using an atomic force microscope. A mechanical force given by the bending deflection of an atomic force microscope probe and its stiffness is applied in the mid-position of the mobile electrode. The mobile electrode is deflected toward the substrate. The obtained experimental curve provides information about the stiffness of investigated structures. As the number of hinges increases, the stiffness of structures is increased. The stiffness has influence on the restoring force of mobile electrode from substrate after the acting signal is removed. The out-of-the plane switches can be monolithically integrated in radio frequency devices.