| AVS 54th International Symposium | |
| Tribology | Wednesday Sessions |
| Session TR1+MN-WeA |
| Session: | Surfaces and Interfaces in MEMS |
| Presenter: | D.A. Hook, Sandia National Laboratiories, North Carolina State University |
| Authors: | D.A. Hook, Sandia National Laboratiories, North Carolina State University S.J. Timpe, Sandia National Laboratiories, University of California Berkeley M.T. Dugger, Sandia National Laboratories J. Krim, North Carolina State University |
| Correspondent: | Click to Email |
Long hydrocarbon and fluorocarbon-based monolayers have been widely used in MEMS applications to prevent release related stiction as well as adhesion as devices are stored for long periods of time.1 It has also been observed that the presence of these monolayers lowers the coefficient of friction in tribological contact. However these same contacts cause rapid degradation of these monolayers.2 The loss of the monolayers contributes to an increase in the adhesive contact force and leads directly to device failure whether it be unpredictable operation of the device or complete cessation of movement. This study reports on degradation of (tridecafluoro-1,1,2,2-tetrahydrooctyl)tris(dimethylamino)-silane (FOTAS) monolayers on normal as well as sliding contacts in MEMS interfaces. The degradation of the monolayer in the normal loading case was probed by measuring the change in adhesive force of the contact over the course of 300,000 normal loading cycles. In the sliding experiment a decrease in oscillation amplitude was used to probe the status of the monolayer. The onset of monolayer degradation was observed in the normal contacting experiment after approximately 80,000 normal contacting cycles, while in the case of sliding degradation was observed almost instantaneously. Work funded by the AFOSR Extreme Friction MURI and Sandia National Labs MESA Project. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.
1Srinivasan, U., Houston, M.R., Howe, R.T., Maboudian, R., "Alkyltrichlorosilane-Based Self-assembled Monolayer Films for Stiction Reduction in Silicon Micromachines", Journal of Microelectromechanical Systems 1998, 7, 252-260.
2DePalma, V., Tillman, N., "Friction and Wear of Self-Assembled Trichlorosilane Monolayer Films on Silicon", Langmuir 1989, 5, 868-872.