ABSTRACT
There has been a tremendous growth in activity over the past seven years in exploring the use of micromachining for the fabrication of novel microstructures, microsensors, and microdevices and also their integration with electronic circuits. Specific application areas have developed to such an extent that there are specialist meetings on the following topics: sensors and actuators,1 microelectromechanical system (MEMS),2 microchemical analysis systems (µTAS),3 optical-MEMS,4 MEMS-electronics,5 chemical sensors,7 and microstructures and microfabricated systems.7 Early examples of MEMS devices and innovations are reviewed in Peterson’s8 classic paper. Up until recently, the MEMS micromachining processes were developed outside the realm of a CMOS line although the advantages of IC fabrication processes and the economies of batch fabrication have been used for production of microdevices at low
cost and high volume. The tremendous successes of microfabricated silicon pressure sensors used for blood pressure monitoring and automotive air intake manifold pressure sensing, ink-jet printer heads, and the air bag accelerometer sensors, and most recently projection overhead display systems, demonstrate the tremendous success of this technology. There are several important differences between MEMS processing and IC processing that make this an exciting and rapidly evolving field:
• Wider range of materials
• Wider range of fabrication processes utilized
• Use of three-dimensional structures
• Material properties are not fully characterized
• Interdisciplinary expertise necessary for successful technology implementation
• CAD tools are not yet fully developed for integrated thermal/mechanical, magnetic, optical, and electronic design
In keeping with the general philosophy of this volume, I will emphasize the fundamental principles and discuss CMOS-compatible processing methods. Selected examples of MEMS devices will be given to illustrate some of the exciting applications of this technology. The reader is referred to the comprehensive survey by Göpel et al.9 and the vast diversity of micromachining and micromanufacturing methods described in recent books by Kovacs,10 Madou,11 and Sze.12 In addition, reference materials include a collection of classic papers by Trimmer,13 texts on sensors by Middlehoek and Audet,14 Ristic,15
Gardener,16 and bio and chemical sensors texts by Janata,17 Madou and Morrison,18 Moseley et al.,19 and Wilson et al.20
