On the physics of stiction and its impact on the reliability of microstructures

Stiction is a very well-known failure mode in micro-electromechanical systems (MEMS). In this paper, a short overview is given of the important physical aspects of stiction in microsystems. The surface forces causing stiction are treated in some detail, and ways of preventing stiction failures are reviewed from a reliability point of view. A statistical calculation method to predict stiction failures is reviewed as well, and a more fundamental analysis of the prediction of stiction failures during normal operation is outlined. Degradation mechanisms in micro-electromechanical systems (MEMS) able to cause stiction due to a lowering of the restoring force, such as creep and charging of dielectrics, are also discussed. It is difficult to conduct accelerated testing on adhesion, but it is shown that mechanisms causing a change in the restoring force can be accelerated. Therefore, some stiction failure modes can well be investigated by accelerated testing.