ABSTRACT
Without question, one of the most exciting technological developments during the last decade of the 20th century was the field of microelectromechanical systems (MEMS). MEMS consists of microfabricated mechanical and electrical structures working in concert for perception and control of the local environment. It was no accident that the development of MEMS accelerated rapidly during the 1990s, as the field was able to take advantage of innovations created during the integrated circuit revolution of the 1960s-80s in terms of processes, equipment, and materials. A well-rounded understanding of MEMS requires a mature knowledge of the materials used to construct the devices, as the material properties of each component can influence device performance. Because the fabrication of MEMS structures often depends on the use of structural, sacrificial, and masking materials on a common substrate, issues related to etch selectivity, adhesion, microstructure, and a host of other properties are important design considerations. A discussion of the materials used in MEMS is really a discussion of the material systems used in MEMS, as the fabrication technologies rarely utilize a single material but rather a collection of materials, each 2-2serving a critical function. It is in this light that this chapter is constructed. The chapter does not attempt to present a comprehensive review of all materials used in MEMS because the list of materials is just too long. It does, however, detail a selection of material systems that illustrate the importance of viewing MEMS in terms of material systems as opposed to individual materials.
