Experimental Investigation of an Embedded Heating Mechanism to Improve RF-MEMS Switches Reliability

Up to date, the remarkable performances and characteristics of MEMS switches and lumped components for Radio Frequency applications (i.e. RF-MEMS) have been demonstrated by several Authors . On the other hand, the reliability of such a technology still has to be fully addressed in order to enable a successful penetration of RF-MEMS technology into the market. Reliability of MEMS/RF-MEMS involves several physical phenomena that can jeopardize their normal operation as well as the stability of their characteristic vs. time. Among such different effects, the authors believe that one of the most important source of malfunctioning is the stiction (i.e. the switch remains stuck in the actuated position when the controlling bias is removed) due to the charge entrapment into the insulator layer and/or the formation of micro-welding. In order to counteract stiction, the authors already presented an innovative RF-MEMS switch design employing an active restoring mechanism, based on an high-resistivity serpentine heater (see Figure 1) to bring it back to its normal operability when stiction occurs. In this work we report on the experimental testing recently performed on such test structures employing the active mechanism, fabricated in the FBK RF-MEMS technology. Firstly we used the Laser Doppler Vibrometer (LDV) integrated into a Polytec MSA-500 optical profilometer to verify the effectiveness of the heating mechanism to induce a movement of the suspended bridge.