This is a research project aimed at developing an improved understanding of the behavior of materials and structural elements (beams, plates, membranes) employed in the manufacture of micro-electro-mechanical systems (MEMS), on the basis of the microstructure exhibited by the materials, with the goal of assessing the performance reliability of such systems. Effective (overall) physical properties, primarily elasticity and strength, and the associated structural response will be evaluated with the recognition that there are a number of microstructural effects that are important at the length scales associated with MEMS but which are unimportant at larger length scales. These include the typical linear dimension of a crystallite within the material being on the same order of magnitude as the thickness of the film, substantial through-thickness variations in grain size and shape, the presence of considerable alignment of the grains (texture) leading to anisotropy of response, and large levels of residual stress arising form the processes used to create may MEMS. Such effects may preclude direct application of classical theories for structural elements, thus necessitating the development of new theories. Furthermore, the variability inherent in the microstructure, which depends strongly on the process conditions, requires a probabilistic description of the material behavior and structural response evaluation aimed at assessing the performance reliability of MEMS. To this end, this research will address: (1) mathematical modeling of material strength and effective properties, (2) influence of microstructure on the structural response of MEMS, and (3) reliability analysis of MEMS using stochastic finite-element methods.
