MEMS TUNABLE CAPACITOR WITH LATERALLY DRIVEN FRAGMENTED ELECTRODES AND ELECTRO-THERMAL ACTUATION
A. MEHDAOUI, D. TSAMADOS, F. CASSET, A. M. IONESCU, P. ANCEY

Abstract. This paper reports on the design, simulation and fabrication of tunable MEMS capacitors with fragmented metal (AlSi 4%) electrodes. We examine a lateral electro-thermal actuation. The capacitance versus displacement is calculated using an analytical model. Evaluation of the impact of fringing fields on the capacitance has been carried out using finite element analysis (FEA). The MEMS capacitors were fabricated using metal surface micromachining with polyimide sacrificial layer. The maximum lateral displacement, corresponding to a value of 5 μm, was obtained near 1 V and 460 mA. The proposed capacitor has a practical tuning range of 15 %. FEA has shown that this figure can be improved with design optimization. The MEMS architecture based on lateral effect and fragmented electrodes does not suffer from the pull-in effect and offers a practical solution for future above-IC capacitors.