Modeling of Wet Stiction in Microelectromechanical Systems (MEMS)

• Published in: Journal of microelectromechanical systems Vol. 16; no. 5; pp. 1276 - 1285
• Main Authors: Hariri, Alireza, Zu, Jean, Ben Mrad, Ridha
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Adhesion; Adhesives; Asperity; Capillarity; Constants; Contact; Deformable models; Exact sciences and technology; Failure analysis; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mathematical models; Mechanical instruments, equipment and techniques; mechanical systems; Microelectromechanical systems; Micromechanical devices; Micromechanical devices and systems; Physics; Plastics; Predictive models; Rough surfaces; Stiction; Studies; Surface fitting; Surface roughness; Surface topography; Ruptures; Stiction; Roughness; Multiple contact; Rough surfaces; Elastic deformation; Experimental study; Adhesion; Surface states; mechanical systems; Capillarity; Surface forces; Failure analysis; Modelling; Hydrophilic compound; Reliability; Microelectromechanical device
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2007.904349

Stiction, which is a term commonly used in micro-electromechanical systems (MEMS) to refer to adhesion, is a major failure mode in MEMS. Undesirable stiction, which results from the contact between surfaces, can severely compromise the reliability of MEMS. In this paper, a model is developed for predicting stiction between uncharged micro parts interacting in a humid environment. In this condition, for hydrophilic surfaces, the capillary and asperity deformation forces are dominant. Here, using a newly developed multiple asperity contact model, a model is developed for the capillary force between rough micro surfaces, and the new model is combined with a newly developed elastic/plastic deformation model for rough surfaces to solve for the equilibrium of the forces. This in turn yields the equilibrium distance between micro surfaces using which the apparent work of adhesion can be found. The theoretical results are compared with the available experimental data from literature. The developed model can be easily used for design purposes. If the topographic data and material constants are known, the desirable adhesion parameters can be quickly found from the model.