Guest Editors' Introduction

Welcome to this special issue on the design and test of microelectromechanical systems (MEMS). Our objective in this issue is to provide the digital design and test community with an introduction to the MEMS technology and an overview of the unique design and test challenges brought forth by this exciting technology. It is our hope that this issue will motivate our community to understand and address these challenges.

MEMS is a catch-all term for integrated systems that can contain electrical, mechanical, optical, fluidic, magnetic, and/or thermic components. Additional acronyms in use include the European term microsystems and the Japanese term micromechatronics. Various well-developed subareas have also created terms such as microoptoelectromechanical systems (MOEMS), microfluidic systems, and chemical total analysis systems (TAS). All of these terms are used to refer to the integrated systems that sense and affect (actuate) the nonelectrical environment that surrounds them. Current commercial successes for MEMS include devices such as airbag accelerometers, automotive and medical pressure sensors, and ink jet printer heads. Altogether, these three products had more than $1 billion of sales in 1996. The latest market study by the System Planning Corporation projects that the overall MEMS market will exceed $11 billion, with the largest projected growth in optical MEMS components. The number of individual MEMS units shipped is predicted to surpass 1 billion, indicating the need for robust design and test methodologies that ensure high-quality devices reach the market in a cost-effective and timely manner.

We hope that the design and test techniques used for pure electronic systems can be leveraged for MEMS, since the latter uses the same batch-fabricated processes developed for VLSI systems. This special issue on the design and test of MEMS presents several aspects of the applicability of this approach.

In the first article, Tamal Mukherjee et al. from Carnegie Mellon University describe their hierarchical approach to the design, synthesis, verification, and test of surface-micromachined MEMS, while a separate article from Salvador Mir and Benoît Charlot at TIMA laboratories describes their approach to the simulation and test of MEMS within standard CAD environments. Nicholas Swart from Analog Devices discusses the challenges of integrated MEMS design (electronics and mechanics on the same die) to meet the rigorous demands of high-volume manufacture. The important role of the package is also discussed in his consideration of three example inertial sensor designs. In the next article, Alain Béliveau et al.'s article from the Air Force Research Laboratory investigates the long-term reliability of MEMS, an important consideration given the increasing use of MEMS in safety-critical applications. Finally, an article from Edward Chan et al. at Stanford University demonstrates the complexity involved in MEMS design by describing the intricate techniques used to characterize the electrostatic behavior of the most primitive MEMS component, the mechanical beam.

MEMS is much more than what we can present in a single issue. It is a true enabling technology that goes beyond the few devices discussed here. However, we hope this special issue whets the appetite of our community and motivates readers not only to further investigate MEMS technology (see, for example, the special issue on MEMS in the August 1998 issue of the Proceedings of the IEEE) but also to actively participate in its continued evolution.