2.1 Introduction

A considerable amount of research is being carried out concerning the design and development of existing systems that reach down into micro- and nanometer scale levels. A technology that considers microscale sensors, actuators, valves, gears, and mirrors embedded in semiconductor chips is referred to as microelectromechanical systems, MEMS in short. In essence, MEMS are small, integrated devices that combine electronics, electrical as well as mechanical elements (Fig. 2.1). The size is in the order of a micrometer level. MEMS design technology is an extended form of traditional fabrication techniques used for IC (Integrated Circuit) manufacturing. MEMS add passive elements such as capacitors and inductors including mechanical elements such as springs, gears, beams, flexures, diaphragms, etc. MEMS are thus the integration of these elements on a single substrate (wafer) developed through more advanced microfabrication and micromachining technology. While the ICs are fabricated by the use of IC process, the mechanical micro components are fabricated using micromachining processes. This process helps in etching away the parts of the selected portions of the wafer. The process can also add new structural layers to form mechanical as well as electromechanical components. Thus, MEMS technology promises to revolutionise many products by combing microfabrication-based microelectronics with micromachining process...