Materials issues in MEMS

The field of microelectromechanical systems (MEMS) involves the interaction of the physical environment (either passively using sensors, or actively using actuators, or both) with electrical signals, through the use of small ("micro") batch-fabricated devices. It takes advantage of many of the wafer-level processing technologies developed for integrated circuits (ICs), while providing new capabilities of sensing and actuating. (It has also established its own, often confusing, jargon; the terms "microstructure" and "mechanism"in the MEMS community both refer to devices.) MEMS is currently one of the fastest growing technologies in microelectronics, in terms of published research papers, scientific conferences, potential application areas, and research funding. Commercial MEMS products are becoming commonplace, including pressure transducers (which have been available since the 1970s), accelerometers, inkjet print heads, chemical sensors, and projection displays. As the field has matured, the impetus for advancement has made some shift from device design to material design. The best devices are being recycled; for example, simple resonators, which have served well as accelerometers, are being used with only minor modifications as gyro-scopes [1] and micromechanical filters [2]. Fabricating the standard poly-silicon accelerometer from a different material, such as nickel, can be a great innovation.