Development, Characterization, and Application of Advanced Coatings for Improving the Reliability of MEMS/NEMS Devices

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Advanced coatings will be developed by molecular and atomic design and tailoring of self-assembled monolayers (SAMs), diamond like carbon films (DLC), and organic/inorganic bilayers (perfluoropolyethers or SAMs on DLC), which are expected to have enhanced functionalities and to greatly improve the reliability of MEMS/NEMS. Understanding of the relationship between micro/nanotribological and mechanical performance of DLC and SAMs and their atomic and molecular structures will be clarified. The microstructure of these coatings will be characterized by various techniques. Their micro/nanoscale tribological properties will be mainly characterized by atomic force microscopy (AFM) and a novel microtriboapparatus developed by our laboratory.The effect of length scale, velocity, relative humidity, and temperature on the performance will be investigated. The micro/nanoscale mechanical properties of advanced DLC coatings will be mainly studied using a nanoindenter and AFM based bending and fatigue tests. The relationship between the process, structure, and performance will be addressed in order to obtain superior performance coatings. Computer modeling of adhesion relevant for MEMS/NEMS will be performed, in which the contribution of meniscus formation, electrostatic, van der Waals forces, and solid bridging will be considered. Knowledge of optimum surface characteristics and advanced coatings will be applied to an industrial application to improve their reliability. The pixel failure mechanisms of digital micromirror devices (DMD) will be studied. Methods to minimize adhesion, stiction/friction and wear will be incorporated in DMD devices. (Two support letters from industry are attached.) This study is expected to be beneficial to both the MEMS/NEMS research and industry.An award would support two graduate students and partially support one postdoctoral researcher. This would provide an opportunity to recruit and fund a minority or woman. The PI and his department have made efforts to attract such students in recent years. The department regularly invites, and provides travel grants for, students, particularly women and minorities, from other schools to attract them for graduate studies. Undergraduate students would work on the project as well. Projects like these provide hands-on opportunities for undergraduate students in a high-tech lab. Past undergraduates in the PI's lab have actually coauthored articles for technical journals. This project will provide additional material for the PI's course on tribology and in soon-to-be-developed nanotribology courses.