4.1 Introduction

This chapter deals with the packaging, and processing requirements essential for the design and development of MEMS (microelectromechanical systems) devices incorporating nanotechnology (NT) or smart materials. Structural materials most desirable for fabrication of actuator beams are identified. Important properties of materials best suited for MEMS devices for aerospace and space applications are summarized. Critical properties for passivation layers widely used in MEMS switches are described. Thermal, mechanical, radio frequency (RF)/microwave, and optical properties of the materials needed in the fabrication of MEMS devices for critical military and aerospace applications are summarized. Important characteristics of soft/hard substrates, piezoelectric, and ferromagnetic materials for fabrication of MEMS devices are discussed.

Properties of important etchants best suited for specific MEMS applications are summarized. Properties of thin-film materials needed in the fabrication of MEMS devices such as MEMS transducers, resonators, and accelerometers are identified. Packaging and sealing material requirements are summarized with emphasis on coefficient of thermal expansion (CTE) match and mechanical integrity of the device. It is important to mention that rapid progress in the design, development, fabrication, and commercialization of MEMS and NT devices is contingent on the availability of advanced materials to the MEMS designers. In addition to traditional materials used in silicon microelectronics involving single crystals and polysilicon, silicon oxide (SiO), silicon nitride (Si ₃N ₄), and aluminum (Al), it is now possible to introduce and integrate a wide variety of metals, alloys, semiconductors, ceramics and glasses, polymers, and elastomers (polyimides) in the design of MEMS...