New test methodology for static and dynamic shape measurements of microelectromechanical systems

Current trends in the miniaturization of structures require the use of smal ler and smaller components. Development of these microcomponents and, in tu rn, of mechanical microstructures/microsystems requires, in addition to the integrated use of advanced design, analysis, and fabrication methodologies , state-of-the-art test and measurement methodologies. We-have developed on e such methodology, optoelectronic laser interferometric microscope (OLIM) methodology, with capabilities for rapid characterization of microelectrome chanical systems (MEMSs); MEMSs are a unique class of mechanisms created us ing integrated circuit (IC) fabrication processes. Microgears and microengi nes, smaller than a gnat's eye, are groups of MEMSs created by such a proce ss. MEMSs offer challenging opportunities for sensor/actuator applications and for improved test methodologies, e.g., shape measurement. This work has produced a new methodology for the characterization of MEMSs. To demonstra te the OLIM methodology, motions of a 64-mu m-diameter microgear, driven at speeds up to 360,000 rpm, are investigated. Manufacturing tolerances resul t in gaps between the microgear and its hub. There gaps allow the microgear to tilt as it rotates. The OLIM methodology permitted measurements of tilt angles of less than 11 mrad, and deflections below 0.5 mu m. Knowing how i ndividual microgears behave is important, e.g., when many such gears are co mbined to form transmissions. (C) 2000 Society of Photo-Optical instrumenta tion Engineers. [S0091-3286(00)02401-6].