A Combined Mechanical and Electrical Characterization Procedure for Investigating the Dynamic Behavior of RF-MEMS Switches

This paper shows the potentialities of two characterization procedures on the electrical and mechanical characterizations of ohmic RF microelectromechanical systems (MEMS) switches. The first is a “fast electrical” procedure that uses an electrical stimulus and monitors the RF signals at the input and output ports of the switch; the second is a “fast hybrid” procedure, i.e., electrical and mechanical, with an electrical input adopted to actuate the device and a mechanical measurement conducted with an optical profilometer, which monitors the displacement and the velocity of the moving membrane when the input electrical signal is applied. Both systems are validated on cantilever and clamped-clamped resistive RF-MEMS switches. We developed these measurement procedures to speed up the measurement process and, consequently, to limit charge trapping during the characterization process. In future analyses, the procedure will be systematically applied to investigate reliability issues when the switch is subjected to multiple impacts and long-term actuation. The use of such procedures will permit separating electrical and mechanical failure mechanisms.

I. Introduction

IT IS well known that RF microelectromechanical system (RF-MEMS) switches are very interesting devices for their RF performances, among them: high isolation and low insertion loss [1]–[3], low cost, small sizes and low weight. Thanks to these and other properties, RF-MEMS switches are attractive devices for space applications, radar enforcement, satellite communication systems and wide band transmissions. Despite their many advantages, the exploitation of these devices has not taken off due to robustness and reliability issues. We can distinguish three families of reliability concerns: mechanical issues (shock, vibration, fractures, and contact degradation, due to repetitive impacts) [4]; electrical issues (stiction due to charge trapping or power handling) [5] and environmental issues (due to humidity, temperature and radiation effect) [6]–[8].