Impact of environmental conditions on the reliability of MEMS components from optical applications

Abstract

Abstract. The reliability design and the lifetime of MEMS from optical applications is strongly dependent on the operating conditions. In optical devices an additional stress is introduced by the temperature gradient appearing during operation. The thermal stress introduced in the structure modifies the component response and its lifetime. The investigated sample is a micromirror fabricated from gold using the MEMS technologies and tested by an atomic force microscope. The scope is to analyse the temperature and relative humidity influence on the mechanical and tribological behaviours. Using a mechanical force given by the bending deflection and stiffness of the AFM probe, the dependence between the applied force and the micromirror deformation is monitored as a function of temperature. By increasing the temperature of structures the stiffness decreases based on the thermal relaxation of the material. If the relative humidity increases the adhesion between the micromirror and substrate is improved based on the capillarity effect. The results obtained are useful to MEMS designers who can predict the micromirror response as a function of the operating conditions with influence on the actuation energy, the accuracy in response and the system lifetime.

A Microtester for Measuring the Reliability of Microdevices in Controlled Environmental Conditions

“…A great deal of work has been carried out to characterize MEMS reliability under different environmental conditions. For instance, Pustan et al investigated the influence of temperature and humidity on the micromirror devices by using the combination of an Atomic Force Microscope and an environmental chamber [2]. It was discovered that the stiffness of the micromirror is reduced by 46% in the temperature range of 20 • C to 140 • C. Zhang et al used the standalone environmental chamber to study the influence of temperature and humidity on the linearity and sensitivity of RF MEMS power sensors [3].…”