Reliability of MEMS

Abstract

MEMS Reliability, especially the study of the reliability of their physical characteristics, is an area that is still in its infancy [1]. However, reliable MEMS exists already and are produced in hundreds of millions MEMS devices and some of them are even intended to use in safety critical applications. The wide variety of materials and physical principles used make it difficult to give general statements about MEMS reliability. However, in several cases reliability is not even studied, confirmed or modeled. Consequently, the lack of long-term reliable devices reduces their level of acceptance considerably. The aging of MEMS is always connected with the occurrence of defects and their mobility. The creation rate and the mobility of the defects are precursors for the aging behavior. The mobility of defects will be enhanced by greater stress gradients. Both, the stress gradient and the defects can be easily determined by means of High resolution X-Ray techniques (HRXRD). The idea behind is now to connect mechanical stress, thermals load and even radiation damage which lead to the corresponding signal drift of MEMS devices with the structural properties like defect density and mobility. High resolution X-ray diffraction techniques (HRXRD) such as the rocking curve (RC) and the reciprocal space maps (RSM) are well suited to detect this features, leading to the drift of the MEMS devices. High Resolution X-ray diffraction (HRXRD) techniques are therefore very powerful tools to study aging through the determination of the stresses and defects in the devices. We are convinces that these advanced state-of-the art X-ray methods will serve as a useful tool for setting up a fundamental understanding of the reliability and also aging problems of MEMS.