DIFFERENT STICTION MECHANISMS IN ELECTROSTATIC MEMS DEVICES: NANOSCALE CHARACTERIZATION BASED ON ADHESION AND FRICTION MEASUREMENTS

摘要

In this work, different stiction mechanisms in electrostatic micro-electromechanical systems (MEMS) and particularly in RF-MEMS switches were studied for the first time. In these devices stiction can be caused by two main mechanisms: dielectric charging and meniscus formation resulting from the adsorbed water film between the switch bridge and the dielectric layer. The effect of each mechanism and their interaction were investigated by measuring the adhesive and friction forces under different electrical stress conditions and relative humidity levels. An atomic force microscope (AFM) was used to perform force-distance and friction measurements on the nanoscale. The study provides an in-depth understanding of different stiction mechanisms, and explanation for the literature reported lifetime measurements for electrostatic capacitive MEMS switches.